WorldWideScience

Sample records for hydrated dolomitic limes

  1. Substrate pH and butterfly bush response to dolomitic lime or steel slag amendment

    Science.gov (United States)

    Steel slag is a fertilizer amendment with a high concentration of calcium oxide, and thus capable of raising substrate pH similar to dolomitic lime. Steel slag, however, contains higher concentrations of some nutrients, such as iron, manganese, and silicon, compared to dolomitic lime. The objectiv...

  2. Effect of Reactivity of Quick Lime on the Properties of Hydrated Lime Sorbent for SO2 Removal

    Institute of Scientific and Technical Information of China (English)

    H.G.Shin; H.Kim; Y.N.Kim; H.S.Lee

    2009-01-01

    The hydration of quick lime and the sulfation of hydrated lime were carried out for verification of relationship between the reactivity of quick lime and the properties of hydrated lime as a sorbent.The effect of reactivity of quick lime was investigated with the change of calcination temperature and time.Results obtained showed that the temperature rise during the hydration of quick limes varied from 31 to 69℃ with the variation of calcination temperature and time.The specific surface area and the sulfation ability of hydrated lime prepared by hydration of quick lime showed a proportional relationship with the reactivity of quick lime.The hydrated lime which was prepared by hydration of quick lime calcined at 1100℃ had the highest reactivity and showed 41.53 m2/g of the specific surface area, 0.16 cm3/g of the pore volume and 87% of the removal efficiency for SO2 removal.

  3. Differences in the rheological properties of calcitic and dolomitic lime slurries: influence of particle characteristics and practical implications in lime-based mortar manufacturing

    Directory of Open Access Journals (Sweden)

    Arizzi, A.

    2012-06-01

    Full Text Available The study of the rheological properties of lime suspensions is a useful means to evaluate the workability of lime mortars. In this work, we studied the flow behaviour of two industrial hydrated limes, one of calcitic and the other of dolomitic composition, by means of two types of rheometer with different geometry and setup mode. The obtained results were interpreted taking into account the differences in microstructure and surface properties of the suspended particles. Calcitic lime dry particles are formed by angular and polydisperse clusters and, once dispersed in water, they behave like thixotropic materials. On the other hand, the dolomitic lime is formed by nanoparticles and small round cluster and it shows a pronounced plastic behaviour in suspension. This fundamental difference between the two materials explains the traditional preference for dolomitic lime mortars for plastering and rendering applications.

    El estudio de las propiedades reológicas de suspensiones de cal es una herramienta muy útil para evaluar la trabajabilidad de morteros de cal. En este trabajo se ha estudiado el comportamiento en suspensión de dos cales hidratadas, de composición calcítica y dolomítica, mediante dos tipos de reómetros con geometría y modalidades distintas de medida. Los resultados obtenidos se han interpretado teniendo en cuenta las diferencias en la microestructura y las propiedades de superficie de las partículas en suspensión. Las partículas de cal calcítica están formadas por aglomerados angulares y polidispersos y, una vez dispersadas en agua, presentan un comportamiento tixotrópico. Por su parte, la cal dolomítica está formada por nanopartículas y pequeños agregados redondeados y muestra en suspensión un pronunciado comportamiento plástico. Esta importante diferencia entre las dos cales explica la preferencia tradicional de morteros de cal dolomítica para aplicaciones en revocos.

  4. Removal of phosphate from greenhouse wastewater using hydrated lime.

    Science.gov (United States)

    Dunets, C Siobhan; Zheng, Youbin

    2014-01-01

    Phosphate (P) contamination in nutrient-laden wastewater is currently a major topic of discussion in the North American greenhouse industry. Precipitation of P as calcium phosphate minerals using hydrated lime could provide a simple, inexpensive method for retrieval. A combination of batch experiments and chemical equilibrium modelling was used to confirm the viability of this P removal method and determine lime addition rates and pH requirements for greenhouse wastewater of varying nutrient compositions. Lime: P ratio (molar ratio of CaMg(OH)₄: PO₄‒P) provided a consistent parameter for estimating lime addition requirements regardless of initial P concentration, with a ratio of 1.5 providing around 99% removal of dissolved P. Optimal P removal occurred when lime addition increased the pH from 8.6 to 9.0, suggesting that pH monitoring during the P removal process could provide a simple method for ensuring consistent adherence to P removal standards. A Visual MINTEQ model, validated using experimental data, provided a means of predicting lime addition and pH requirements as influenced by changes in other parameters of the lime-wastewater system (e.g. calcium concentration, temperature, and initial wastewater pH). Hydrated lime addition did not contribute to the removal of macronutrient elements such as nitrate and ammonium, but did decrease the concentration of some micronutrients. This study provides basic guidance for greenhouse operators to use hydrated lime for phosphate removal from greenhouse wastewater.

  5. Simulation of self-healing of dolomitic lime mortar

    NARCIS (Netherlands)

    Lubelli, B.A.; Nijland, T.G.; Hees, R.P.J. van

    2011-01-01

    In the present research a test procedure was set up to reproduce self-healing on lime-based (both pure calcium and magnesium-calcium) mortar specimens in laboratory. After few months testing, during which the specimens were subjected to wet-dry cycles, thin sections of the specimens were prepared an

  6. Simulation of the self-healing of dolomitic lime mortar

    NARCIS (Netherlands)

    Lubelli, B.; Nijland, T.G.; Hees, R.P.J. van

    2012-01-01

    A test procedure was set up to reproduce laboratory self-healing on lime-based (both pure calcium and magnesium-calcium) mortar specimens. After a few months of testing, during which time the specimens were submitted to wet-dry cycles, thin sections of the specimens were prepared and observed using

  7. Evaluation of Hydrated Lime Filler in Asphalt Mixtures

    Directory of Open Access Journals (Sweden)

    Mohammed Abbas Hasan Al-Jumaily

    2008-01-01

    Full Text Available Mineral filler is one of important materials and affecting on properties and quality of asphalt mixtures .There are different types of mineral filler depended on cost and quality , the matter encourages us to achieve this study to evaluate hydrated lime filler effects on properties of asphalt mixes related with strength and durability. Conventional asphaltic concrete mixtures with Portland cement and soft sandstone fillers and mixtures modified with hydrated lime were evaluated for their fundamental engineering properties as defined by Marshall properties , index of retained strength , indirect tensile strength , permanent deformation characteristics , and fatigue resistance .A typical dense graded mixture employed in construction of surface course pavement in Iraq in accordance with SCRB specifications was used .The materials used in this study included mineral aggregate materials (coarse and fine sizes were originally obtained from Najaf Sea quarries and two grades of asphalt cements produced from Daurah refinery which are D47 and D66 . The physical properties , stiffness modulus and chemical composition are evaluated for the recovered asphalt cement from prepared asphalt mixes containing various filler types .The paper results indicated that the addition of hydrated lime as mineral filler improved the permanent deformation characteristics and fatigue life and the use of hydrated lime will decrease the moisture susceptibility of the asphalt mixtures.

  8. Effect of CeO2 on Sintering and Hydration Resistance of Natural Dolomite

    Institute of Scientific and Technical Information of China (English)

    XUYan-qing; CHENZhao-you

    1996-01-01

    The sinteribility and hydration resistance of high pure natural dolomite doped with CeO2 addition were studied.It is found that the addition of CeO2 to dolomite can significantly improve the sintering and the resistane to hydration of dolomite.Doping 0.25% CeO2,followed by firing at 1600℃ for 4 hours,a dense doloma clinker with bulk density>3.25 g/cm3, apparent porosity<1.0% and excellent hydration resistance has been obtained.

  9. Dolomitic lime amendment affects pine bark substrate pH, nutrient availability, and plant growth: A review

    Science.gov (United States)

    Dolomitic lime (DL) is one of the most commonly used fertilizer amendments in nursery container substrates. It is used to adjust pH of pine bark substrates from their native pH, 4.1 to 5.1, up to about pH 6. Additions of DL have been shown to be beneficial, inconsequential, or detrimental dependin...

  10. Potential Use Of Carbide Lime Waste As An Alternative Material To Conventional Hydrated Lime Of Cement-Lime Mortars

    OpenAIRE

    Al Khaja, Waheeb A.

    1992-01-01

    The present study aimed at the possibility of using the carbide lime waste as an alternative material to the conventional lime used for cement-lime mortar. The waste is a by-product obtained in the generation of acetylene from calcium carbide. Physical and chemical properties of the wastes were studied. Two cement-lime-sand mix proportions containing carbide lime waste were compared with the same mix proportions containing conventional lime along with a control mix without lime. Specimens wer...

  11. Hydration products of lime-metakaolin pastes at ambient temperature with ageing

    Energy Technology Data Exchange (ETDEWEB)

    Gameiro, A., E-mail: agameiro@lnec.pt [National Laboratory of Civil Engineering, Materials Department, Av. do Brasil, 101, 1700 Lisbon (Portugal); Santos Silva, A., E-mail: ssilva@lnec.pt [National Laboratory of Civil Engineering, Materials Department, Av. do Brasil, 101, 1700 Lisbon (Portugal); Veiga, R., E-mail: rveiga@lnec.pt [National Laboratory of Civil Engineering, Buildings Department, Av. do Brasil, 101, 1700 Lisbon (Portugal); Velosa, A., E-mail: avelosa@ua.pt [Department of Civil Engineering, Geobiotec, University of Aveiro, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal)

    2012-05-10

    Highlights: Black-Right-Pointing-Pointer We study the compounds formed in lime/MK blended pastes and their stability over time. Black-Right-Pointing-Pointer Different mixes of lime/MK pastes show different reaction kinetics during curing time, being the pozzolanic compounds formed directly proportional to the lime by MK replacement. Black-Right-Pointing-Pointer Some pozzolanic products are found to be unstable during the hydration reaction employed in our study. - Abstract: Mortars constituted of lime mixtures with pozzolanic additions have been extensively used in the past for the construction of historic and traditional buildings. This paper presents the results of blended pastes of lime and metakaolin (MK), namely compounds formed and their stability over time. This research is part of an extensive study aiming at the formulation of lime based mortars for restoration purposes. It has been shown for several years that MK has been applied in inorganic binders due to its capacity to react vigorously with calcium hydroxide (CH). In the presence of water originating a series of major hydrated phases, namely tetra calcium aluminate hydrate (C{sub 4}AH{sub 13}), calcium silicates hydrates (CSH) and calcium aluminium silicate hydrates (stratlingite - C{sub 2}ASH{sub 8}). Several blended pastes of lime and MK, with different substitution rates of lime by MK (wt%) were prepared and cured at a temperature of 20 Degree-Sign C and relative humidity RH > 95%. The phase composition of the formed hydrated phases was determined by X-ray diffraction (XRD) and simultaneous thermal analysis (TG-DTA). The obtained results showed that lime/MK pastes compositions displayed different reaction kinetics during curing time, being the pozzolanic products content directly proportional to the substitution rate of lime by MK. Also, a relationship between the increase stratlingite content and the MK substitution rate of lime by MK was found.

  12. Assessing the effects of soil liming with dolomitic limestone and sugar foam on soil acidity, leaf nutrient contents, grape yield and must quality in a Mediterranean vineyard

    Energy Technology Data Exchange (ETDEWEB)

    Olego, M.A.; Visconti, F.; Quiroga, M.J.; Paz, J.M. De; Garzón-Jimeno, E.

    2016-11-01

    Aluminium toxicity has been recognized as one of the most common causes of reduced grape yields in vineyard acid soils. The main aim of this study was to evaluate the effect of two liming materials, i.e. dolomitic lime and sugar foam, on a vineyard cultivated in an acid soil. The effects were studied in two soil layers (0-30 and 30-60 cm), as well as on leaf nutrient contents, must quality properties and grape yield, in an agricultural soil dedicated to Vitis vinifera L. cv. ‘Mencía’ cultivation. Data management and analysis were performed using analysis of variance (ANOVA). As liming material, sugar foam was more efficient than dolomitic limestone because sugar foam promoted the highest decrease in soil acidity properties at the same calcium carbonate equivalent dose. However, potassium contents in vines organs, including leaves and berries, seemed to decrease as a consequence of liming, with a concomitant increase in must total acidity. Soil available phosphorus also decreased as a consequence of liming, especially with sugar foam, though no effects were observed in plants. For these reasons fertilization of this soil with K and P is recommended along with liming. Grape yields in limed soils increased, although non-significantly, by 30%. This research has therefore provided an important opportunity to advance in our understanding of the effects of liming on grape quality and production in acid soils. (Author)

  13. Advanced treatment of swine wastewater using an agent synthesized from amorphous silica and hydrated lime.

    Science.gov (United States)

    Tanaka, Yasuo; Hasegawa, Teruaki; Sugimoto, Kiyomi; Miura, Keiichi; Aketo, Tsuyoshi; Minowa, Nobutaka; Toda, Masaya; Kinoshita, Katsumi; Yamashita, Takahiro; Ogino, Akifumi

    2014-01-01

    Advanced treatment using an agent synthesized from amorphous silica and hydrated lime (M-CSH-lime) was developed and applied to swine wastewater treatment. Biologically treated wastewater and M-CSH-lime (approximately 6 w/v% slurry) were fed continuously into a column-shaped reactor from its bottom. Accumulated M-CSH-lime gradually formed a bed layer. The influent permeated this layer and contacted the M-CSH-lime, and the treatment reaction progressed. Treated liquid overflowing from the top of the reactor was neutralized with CO₂gas bubbling. The colour removal rate approximately exceeded 50% with M-CSH-lime addition rates of > 0.15 w/v%. The removal rate of PO(3⁻)(4) exceeded 80% with the addition of>0.03 w/v% of M-CSH-lime. The removal rates of coliform bacteria and Escherichia coli exceeded 99.9% with > 0.1 w/v%. Accumulated M-CSH-lime in the reactor was periodically withdrawn from the upper part of the bed layer. The content of citric-acid-soluble P₂O₅ in the recovered matter was>15% when the weight ratio of influent PO(3⁻)(4) -P to added M-CSH-lime was > 0.15. This content was comparable with commercial phosphorus fertilizer. The inhibitory effect of recovered M-CSH-lime on germination and growth of leafy vegetable komatsuna (Brassica rapa var. perviridis) was evaluated by an experiment using the Neubauer's pot. The recovered M-CSH-lime had no negative effect on germination and growth. These results suggest that advanced water treatment with M-CSH-lime was effective for simultaneous removal of colour, [Formula: see text] and coliform bacteria at an addition rate of 0.03-0.15 w/v%, and that the recovered M-CSH-lime would be suitable as phosphorus fertilizer.

  14. Local development of affordable lime in southern Africa: Project Summary Report

    OpenAIRE

    1998-01-01

    Lime is an important and versatile chemical used in a wide range of industrial and other applications. The term lime, which strictly refers to calcium oxide (CaO), is applied to a range of products arising from the grinding, calcination and hydration of limestone and dolomite. Many less developed countries do not have adequate lime production and this leads to problems associated with under-utilisation of lime. In particular, insufficient application of agricultural lime can lead to soil acid...

  15. Analysis of cubic and orthorhombic C3A hydration in presence of gypsum and lime

    KAUST Repository

    Kirchheim, A. P.

    2009-02-26

    Field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) have been used to study the microstructural changes and phase development that take place during the hydration of cubic (pure) and orthorhombic (Na-doped) tricalcium aluminate (C3A) and gypsum in the absence and presence of lime. The results demonstrate that important differences occur in the hydration of each C3A polymorph and gypsum when no lime is added; orthorhombic C3A reacts faster with gypsum than the cubic phase, forming longer ettringite needles; however, the presence of lime slows down the formation of ettringite in the orthorhombic sample. Additional rheometric tests showed the possible effects on the setting time in these cementitious mixes.

  16. Practice of raising shaft kiln dolomitic lime content of Xingsteel%邢钢提高竖窑白云灰含量的实践

    Institute of Scientific and Technical Information of China (English)

    霍志军; 王君朝

    2011-01-01

    随着邢钢精品钢战略的纵深实施,精品钢比例日益增加,炼钢对白云灰质量的要求也越来越高,所以提高白云灰质量势在必行。通过对3^#竖窑白云灰的质量分析,制定相应对策,保证白云石化学成分稳定,取得了显著的经济效益。%With the deep implementation of perfect quality steel strategy of Xingsteel, the proportion of perfect quality steel is increased day by day, the requirement of the quality of dolomitic lime for steelmaking of Xingsteel is becoming higher and higher. Therefore the improvement of dolomitic lime quality is imperative under the situation. Through the analysis of dolomitic lime quality of No.3 shaft kiln, the corresponding countermeasures are made to ensure the stability of chemical composition of dolomite, the remarkable economic benefit is achieved

  17. Lime

    Science.gov (United States)

    Miller, M.

    2006-01-01

    In 2005, US lime production was 20 Mt with a value of $1.5 billion. Production was unchanged compared with 2004. Captive production was 1.4 Mt. US consumption was 20.2 Mt. Most of the US lime trade was with Canada and Mexico. Despite some disruptions due to hurricanes Katrina and Rita, normal sales activities remained healthy.

  18. Iron blast furnace slag/hydrated lime sorbents for flue gas desulfurization.

    Science.gov (United States)

    Liu, Chiung-Fang; Shih, Shin-Min

    2004-08-15

    Sorbents prepared from iron blast furnace slag (BFS) and hydrated lime (HL) through the hydration process have been studied with the aim to evaluate their reactivities toward SO2 under the conditions prevailing in dry or semidry flue gas desulfurization processes. The BFS/HL sorbents, having large surface areas and pore volumes due to the formation of products of hydration, were highly reactive toward SO2, as compared with hydrated lime alone (0.24 in Ca utilization). The sorbent reactivity increased as the slurrying temperature and time increased and as the particle size of BFS decreased; the effects of the liquid/solid ratio and the sorbent drying conditions were negligible. The structural properties and the reactivity of sorbent were markedly affected by the BFS/HL ratio; the sorbent with 30/70 ratio had the highest 1 h utilization of Ca, 0.70, and SO2 capture, 0.45 g SO2/g sorbent. The reactivity of a sorbent was related to its initial specific surface area (Sg0) and molar content of Ca (M(-1)); the 1 h utilization of Ca increased almost linearly with increasing Sg0/M. The results of this study are useful to the preparation of BFS/HL sorbents with high reactivity for use in the dry and semidry processes to remove SO2 from the flue gas.

  19. Effect of Some Admixtures on the Hydration of Silica Fume and Hydrated Lime

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The effects of sodium salt of naphthalene formaldehyde sulfonic acid and stearic acid on the hydration of silica fume and Ca(0H)2 have been investigated. The hydration was carried out at 60℃ and W/S ratio of 4 for various time intervals namely, 1, 3, 7 and 28 days and in the presence of 0.2% and 5% superplasticizer and stearic acid. The results of the hydration kinetics show that both admixtures accelerate the hydration reaction of silica fume and calcium hydroxide during the first 7 days. Whereas, after 28 days hydration there is no significant effect. Generally, most of free calcium hydroxide seems to be consumed after 28 days. In addition, the phase composition as well as the microstructure of the formed hydrates was examined by using X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) respectively.

  20. Full quantitative phase analysis of hydrated lime using the Rietveld method

    Energy Technology Data Exchange (ETDEWEB)

    Lassinantti Gualtieri, Magdalena, E-mail: magdalena.gualtieri@unimore.it [Dipartimento Ingegneria dei Materiali e dell' Ambiente, Universita Degli Studi di Modena e Reggio Emilia, Via Vignolese 905/a, I-41100 Modena (Italy); Romagnoli, Marcello; Miselli, Paola; Cannio, Maria [Dipartimento Ingegneria dei Materiali e dell' Ambiente, Universita Degli Studi di Modena e Reggio Emilia, Via Vignolese 905/a, I-41100 Modena (Italy); Gualtieri, Alessandro F. [Dipartimento di Scienze della Terra, Universita Degli Studi di Modena e Reggio Emilia, I-41100 Modena (Italy)

    2012-09-15

    Full quantitative phase analysis (FQPA) using X-ray powder diffraction and Rietveld refinements is a well-established method for the characterization of various hydraulic binders such as Portland cement and hydraulic limes. In this paper, the Rietveld method is applied to hydrated lime, a non-hydraulic traditional binder. The potential presence of an amorphous phase in this material is generally ignored. Both synchrotron radiation and a conventional X-ray source were used for data collection. The applicability of the developed control file for the Rietveld refinements was investigated using samples spiked with glass. The results were cross-checked by other independent methods such as thermal and chemical analyses. The sample microstructure was observed by transmission electron microscopy. It was found that the consistency between the different methods was satisfactory, supporting the validity of FQPA for this material. For the samples studied in this work, the amount of amorphous material was in the range 2-15 wt.%.

  1. Effects of hydrated lime and quicklime on the decay of buried human remains using pig cadavers as human body analogues.

    Science.gov (United States)

    Schotsmans, Eline M J; Denton, John; Dekeirsschieter, Jessica; Ivaneanu, Tatiana; Leentjes, Sarah; Janaway, Rob C; Wilson, Andrew S

    2012-04-10

    Recent casework in Belgium involving the search for human remains buried with lime, demonstrated the need for more detailed understanding of the effect of different types of lime on cadaver decomposition and its micro-environment. Six pigs (Sus scrofa) were used as body analogues in field experiments. They were buried without lime, with hydrated lime (Ca(OH)(2)) and with quicklime (CaO) in shallow graves in sandy loam soil in Belgium and recovered after 6 months of burial. Observations from these field recoveries informed additional laboratory experiments that were undertaken at the University of Bradford, UK. The combined results of these studies demonstrate that despite conflicting evidence in the literature, hydrated lime and quicklime both delay the decay of the carcass during the first 6 months. This study has implications for the investigation of clandestine burials and for a better understanding of archaeological plaster burials. Knowledge of the effects of lime on decomposition processes also has bearing on practices involving burial of animal carcasses and potentially the management of mass graves and mass disasters by humanitarian organisations and DVI teams.

  2. Simultaneous removal of colour, phosphorus and disinfection from treated wastewater using an agent synthesized from amorphous silica and hydrated lime.

    Science.gov (United States)

    Yamashita, Takahiro; Aketo, Tsuyoshi; Minowa, Nobutaka; Sugimoto, Kiyomi; Yokoyama, Hiroshi; Ogino, Akifumi; Tanaka, Yasuo

    2013-01-01

    An agent synthesized from amorphous silica and hydrated lime (CSH-lime) was investigated for its ability to simultaneously remove the colour, phosphorus and disinfection from the effluents from wastewater treatment plants on swine farms. CSH-lime removed the colour and phosphate from the effluents, with the colour-removal effects especially high at pH 12, and phosphorous removal was more effective in strongly alkaline conditions (pH > 10). Colour decreased from 432 +/-111 (mean +/- SD) to 107 +/- 41 colour units and PO4(3-)P was reduced from 45 +/- 39 mg/L to undetectable levels at the CSH-lime dose of 2.0% w/v. Moreover, CSH-lime reduced the total organic carbon from 99.0 to 37.9 mg/L at the dose of 2.0% w/v and was effective at inactivating total heterotrophic and coliform bacteria. However, CSH-lime did not remove nitrogen compounds such as nitrite, nitrate and ammonium. Colour was also removed from dye solutions by CSH-lime, at the same dose.

  3. Modeling dry-scrubbing of gaseous HCl with hydrated lime in cyclones with and without recirculation

    Energy Technology Data Exchange (ETDEWEB)

    Chibante, Vania G., E-mail: vaniachi@fe.up.pt [DEQ/LEPAE, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias s/n, 4200-465 Porto (Portugal); Fonseca, Ana M., E-mail: afonseca@ufp.pt [CIAGEB, Universidade Fernando Pessoa, Praca 9 Abril 349, 4249-004 Porto (Portugal); Salcedo, Romualdo R., E-mail: rsalcedo@fe.up.pt [DEQ/LEPAE, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias s/n, 4200-465 Porto (Portugal); Advanced Cyclone Systems S.A., Rua de Salazares, 842, Ed. Promonet, Porto (Portugal)

    2010-06-15

    A mathematical model describing the dry-scrubbing of gaseous hydrogen chloride (HCl) with solid hydrated lime particles (Ca(OH){sub 2}) was developed and experimentally verified. The model applies to cyclone systems with and without recirculation, where reaction and particle collection occurs in the same processing unit. The Modified Grain Model was selected to describe the behavior of the reaction process and it was assumed that the gas and the solid particles flow in the reactor with a plug flow. In this work, this behavior is approximated by a cascade of N CSTRs in series. Some of the model parameters were estimated by optimization taking into account the experimental results obtained. A good agreement was observed between the experimental results and those predicted by the model, where the main control resistance is the diffusion of the gaseous reactant in the layer of solid product formed.

  4. Physical Properties and Hydration Resistance of CeO2—and CeO2/Fe2O3—Bearing Dolomite Refractory Products

    Institute of Scientific and Technical Information of China (English)

    XUYanqing; CHENKaixian

    1998-01-01

    Dolomite refractory products with excellent hydration resistance have been produced by using CeO2-and CeO2/Fe2O3-bearing dolomite clinkers,Their physical properties as well as hydration resistance have been investigated,The addition of CeO2 has little harmful effect on the high temperature properties of dolomite refractory products such as hot MOR and slag resistance,And the shelf lives of the dolomite refractory products containing CeO2 and CeO2/Fe2O3 additions at the same condition are two times that of the common dolomite refractory produt.The dolomite refractory product containing CeO2/Fe2O3 combination possesses the best hydration resistance,but gives poor slag resistance.

  5. Effect of hydrated lime and cement on moisture damage of recycled mixtures with foamed bitumen and emulsion

    OpenAIRE

    Nosetti, R.A.; Pérez Jiménez, Félix Edmundo; Martínez Reguero, Adriana Haydée; Miró Recasens, José Rodrigo

    2016-01-01

    Cold recycling with foamed bitumen can be used as a sustainable and cost-effective rehabilitation technique. This paper focuses on the evaluation of the resistance to the water action in mixtures with reclaimed asphalt pavement (RAP) and foamed bitumen by means of indirect tensile test, comparing the effect of two active fillers: cement and hydrated lime. Additionally, mixtures recycled with RAP and asphalt emulsions were also tested in order to compare the response of both technologies. Resu...

  6. Short-term effects of hydrated lime and quicklime on the decay of human remains using pig cadavers as human body analogues: Laboratory experiments.

    Science.gov (United States)

    Schotsmans, Eline M J; Denton, John; Fletcher, Jonathan N; Janaway, Robert C; Wilson, Andrew S

    2014-05-01

    Contradictions and misconceptions regarding the effect of lime on the decay of human remains have demonstrated the need for more research into the effect of different types of lime on cadaver decomposition. This study follows previous research by the authors who have investigated the effect of lime on the decomposition of human remains in burial environments. A further three pig carcasses (Sus scrofa), used as human body analogues, were observed and monitored for 78 days without lime, with hydrated lime (Ca(OH)2) and with quicklime (CaO) in the taphonomy laboratory at the University of Bradford. The results showed that in the early stages of decay, the unlimed and hydrated lime cadavers follow a similar pattern of changes. In contrast, the application of quicklime instigated an initial acceleration of decay. Microbial investigation demonstrated that the presence of lime does not eliminate all aerobic bacteria. The experiment also suggested that lime functions as a sink, buffering the carbon dioxide evolution. This study complements the field observations. It has implications for the investigation of time since death of limed remains. Knowledge of the effects of lime on decomposition processes is of interest to forensic pathologists, archaeologists, humanitarian organisations and those concerned with disposal of animal carcasses or human remains in mass disasters. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  7. Hidrólise da cana-de-açúcar com cal virgem ou cal hidratada Hydrolysis of cane sugar with lime or hydrated lime

    Directory of Open Access Journals (Sweden)

    Diego Azevedo Mota

    2010-06-01

    Full Text Available Objetivou-se estudar o efeito do tratamento alcalino da cana-de-açúcar com cal virgem ou cal hidratada sobre a composição bromatológica e a digestibilidade in vitro da matéria seca, da fibra em detergente neutro e da fibra em detergente ácido. Utilizou-se um delineamento inteiramente casualizado em esquema fatorial 3 × 3, composto de três formas de processamento da cana (in natura; cana hidrolisada com 0,5% de cal virgem; e cana hidrolisada com 0,5% de cal hidratada e três tempos de armazenamento (12, 36 e 60 horas. As formas de processamento influenciaram os teores de matéria orgânica, matéria mineral, carboidratos totais e hemicelulose, assim como os teores de fibra em detergente neutro e nutrientes digestíveis totais. Os tempos de armazenamento influenciaram os teores de proteína bruta, matéria orgânica, carboidratos totais e hemicelulose. Entre os minerais, somente o teor de cálcio teve aumento com a inclusão de ambos os tipos de cal em relação à cana-de-açúcar, que não sofreu o processo de hidrólise. Os coeficientes de digestibilidade da matéria seca e da fibra em detergente neutro aumentaram com a hidrólise da cana em comparação à cana in natura. A hidrólise com cal hidratada ou com cal virgem mantém o valor nutricional da cana-de-açúcar, permitindo que possa ser utilizada depois de até 60 horas de armazenamento.The objective of the present work was to evaluate the effect of the alkaline treatment of sugarcane with virgin lime or hydrated lime on the bromatologic composition and in vitro digestibility of dry matter, neutral detergent fiber, and acid detergent fiber. It was used a complete random design with a 3 × 3 factorial scheme composed by three forms of of sugarcane processing (in natura sugarcane; hydrolyzed sugarcane with 0.5% virgin lime; and hydrolyzed sugarcane with 0.5% hydrated lime and three storage times (12, 36 and 60 hours. The forms of processing changed the contents of organic matter

  8. Long-term effects of hydrated lime and quicklime on the decay of human remains using pig cadavers as human body analogues: Field experiments.

    Science.gov (United States)

    Schotsmans, Eline M J; Fletcher, Jonathan N; Denton, John; Janaway, Robert C; Wilson, Andrew S

    2014-05-01

    An increased number of police enquiries involving human remains buried with lime have demonstrated the need for more research into the effect of different types of lime on cadaver decomposition and its micro-environment. This study follows previous studies by the authors who have investigated the effects of lime on the decay of human remains in laboratory conditions and 6 months of field experiments. Six pig carcasses (Sus scrofa), used as human body analogues, were buried without lime with hydrated lime (Ca(OH)2) and quicklime (CaO) in shallow graves in sandy-loam soil in Belgium and recovered after 17 and 42 months of burial. Analysis of the soil, lime and carcasses included entomology, pH, moisture content, microbial activity, histology and lime carbonation. The results of this study demonstrate that despite conflicting evidence in the literature, the extent of decomposition is slowed down by burial with both hydrated lime and quicklime. The more advanced the decay process, the more similar the degree of liquefaction between the limed and unlimed remains. The end result for each mode of burial will ultimately result in skeletonisation. This study has implications for the investigation of clandestine burials, for a better understanding of archaeological plaster burials and potentially for the interpretation of mass graves and management of mass disasters by humanitarian organisation and DVI teams. Copyright © 2014. Published by Elsevier Ireland Ltd.

  9. Influence of aggregate and supplementary cementitious materials on the properties of hydrated lime (CL90s mortars

    Directory of Open Access Journals (Sweden)

    S. Pavía

    2016-11-01

    Full Text Available Hydrated lime is a historic material currently used in conservation. It hardens slowly by carbonation slowing construction however, supplementary cementitious materials accelerate hardening enhancing strength. Hydrated-lime mortars with rice husk ash–RHA-; ground granulated blastfurnace slag–GGBS- and increasing amounts of two aggregates were studied. Increasing aggregate lowered strength as interfacial zones proliferate; it lowered hygric properties and raised water demand. Aggregate content/composition didn’t affect the high water retention. For the higher aggregate contents (90 days, limestone mortars are c.20% stronger than silica mortars while the (1:1 silica sand mortars are 56% stronger in flexion. Additions increased strength with little impact on hygric properties. GGBS increased strength c.six times. RHA increased strength with little impact on hygric properties due to its great specific surface and high water-demand increasing porosity. GGBS and RHA properties ruling hydrate production and the kinetics of the pozzolanic reaction are considered partially responsible for the mortar property variation.

  10. Fundamentals of Sintering Dolomite

    Institute of Scientific and Technical Information of China (English)

    LIMaoqiang

    1996-01-01

    The difficulties in sintering of dolomite rise form the low mutual diffusibilites of Ca2+ in MgO and Mg2+ in CaO ,and from unique pore and agglomerate structures formed after calcination of dolomite.These microstructures in decompsoed dolomite play a great role in inhibition of densification during sintering.The measures ,which can destroy these stuctures,such as hydration or isostatic pressing after calcination of dolomite,result in increasing the sintered density and reducting the sintering temperature,Addition of ome oxide such as Fe2O3,ater the sintering mechanism from solid state sintering to liquid phase sintering,therefore,dense dolomite ody can be obtained at relatively low sintering temperature,Com-minution of dolomite before its calcination can lower the sintering temperature and enhance the sinterd ensity due to increasing both the quantity and homogeneity of Fe2O3 in dolomite.

  11. Influence of supplementary cementitious materials on water transport kinetics and mechanical properties of hydrated lime and cement mortars

    Directory of Open Access Journals (Sweden)

    Ince, C.

    2015-06-01

    Full Text Available The purpose of this paper is an investigation of the possible role of supplementary cementitious materials (SCMs on water transport kinetics and mechanical properties of hydrated lime (CL90 and Portland cement (PC mortars. The properties of hydrated lime are significantly different from those of cement and therefore modifying fresh and hardened properties of these mortars are vital for mortar/substrate optimisation in masonry construction. The parameters investigated in this paper often are the main barriers to the use of hydrated lime in construction practice. The results show that transfer sorptivity and time to dewater freshly-mixed hydrated lime mortars can be modified when binder is partially replaced with SCMs. Compressive strength of CL90 mortars is increased systematically with the increased replacement levels of SCMs and the results are supported with the microstructural images. The ability to modify the water transport kinetics and mechanical properties allows compatibility between the mortar and the substrate unit in masonry construction.El objetivo de este artículo es investigar el papel de los materiales cementantes suplementarios (SCMs en la cinética de transporte del agua y en las propiedades mecánicas de los morteros de cal hidratada (CL90 y cemento Portland. Las propiedades de la cal hidratada son significativamente diferentes a las del cemento y por lo tanto el control de las propiedades de los morteros frescos y endurecidos es fundamental en la optimización mortero/substrato en albañilería. Los parámetros estudiados en este trabajo son a menudo las principales barreras para el uso de la cal hidratada en la práctica de la construcción. Los resultados indican que la absortividad y el tiempo necesario para deshidratar morteros de cal hidratada recién mezclados pueden ser controlados cuando el conglomerante es parcialmente remplazado por SCMs. La resistencia a compresión de los morteros CL90 aumenta sistem

  12. Managing Salmonella Typhimurium and Escherichia coli O157:H7 in soil with hydrated lime - An outdoor study in lysimeters and field plots.

    Science.gov (United States)

    Nyberg, Karin A; Vinnerås, Björn; Albihn, Ann

    2014-01-01

    An outbreak of Salmonella Typhimurium or E. coli O157:H7 among domestic animals can have great financial consequences for an animal enterprise but also be a threat for public health as there is a risk for transmission of the infection through the environment. In order to minimize disease transmission, it is important to treat not only the affected animals but also the areas on which they have been kept. In the present study, the effect of hydrated lime as a treatment for Salmonella Typhimurium or E. coli O157:H7 contaminated soil was investigated. The study was performed outdoors, in a lysimeter system and in field plots. The soils were spiked with Salmonella Typhimurium and/or E. coli O157:H7 and hydrated lime was added at three different concentrations (0.5, 1 and 2%). Sampling was performed over one month, and the levels of bacteria were analyzed by standard culture methods. In addition, the soil pH was monitored throughout the study. The results showed that application of 0.5-1 kg hydrated lime per m(2) reduced both Salmonella Typhimurium and E. coli O157:H7 numbers to below the detection limit (2 log10 CFU g-1 soil) in 3-7 days. Lower application rates of hydrated lime did not reduce pathogen numbers in the lysimeter study, but in the field plots no E. coli O157:H7 was detected at the end of the four-week study period regardless of hydrated lime application. A recommended strategy for treating a Salmonella Typhimurium or E. coli O157:H7 contaminated soil could therefore be to monitor the pH over the time of treatment and to repeat hydrated lime application if a decrease in pH is observed.

  13. Characterization of early-age hydration processes in lime-ceramic binders using isothermal calorimetry, X-ray diffraction and scanning electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Jerman, Miloš; Tydlitát, Vratislav; Keppert, Martin; Čáchová, Monika; Černý, Robert, E-mail: cernyr@fsv.cvut.cz

    2016-06-10

    Highlights: • Early age hydration processes in lime-ceramic binders are analyzed within a wide range of component ratios. • The applied waste ceramic dust exhibits partial hydraulic properties, ettringite and calcite are formed. • Transition from tobermorite- to jennite-like structures is identified by SEM within the first 48 h. • The highest specific hydration heat after 300 h, 63 J/g, is measured for the binder containing 70% ceramic. • Substantial effect of the heat of wetting is observed, ranging from 10 J/g for lime to 3.9 J/g for ceramic. - Abstract: Early-age hydration processes in a lime-ceramic-water system are analyzed within the whole range of possible lime/ceramic ratios. The isothermal calorimetry shows a substantial effect of the heat of wetting on the total heat evolved, ranging from 10 J/g for lime to 3.9 J/g for ceramic. The highest specific hydration heat of 63 J/g during the analyzed 300-h hydration period exhibits the blended binder containing 70% ceramic and 30% lime which correlates well with the highest compressive and bending strengths of the paste prepared using this blend. Portlandite, ettringite and calcite are the main phases identified by the X-ray diffraction analysis after the hydration of ceramic-rich blends. According to the results of scanning electron microscopy, the initial course of pozzolanic reaction is for this type of binders characterized by the transition from tobermorite-like calcium-silicate-hydrate structures into jennite-like structures within the first 48 h. Blends with the ceramic content lower than 70% show a high portion of portlandite, calcite is present in low amount, and the jennite-like structures are observed after 48 h, following the initial formation of components with a very high Ca content. The favorable properties of the ceramic-rich blended binders can be explained by the partial hydraulic character of the ceramic. With the specific hydration heat of 29 J/g after 300 h and compressive strength

  14. Analysis of limestones and dolomites by x-ray fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wheeler, B.D.

    1999-07-01

    Sources of calcium are generally widespread and quite extensive. These sources are limestone, dolomite, marl, chalk, and oyster shell. Cement plants account for nearly half of the demand, while two hundred lime plants in the US and Puerto Rico consume about twenty five percent. Since the chemical composition of the limestone and other sources of calcium is critical in the cement and lime industry, particularly for the deleterious compounds such as sodium oxide, Na{sub 2}O, magnesium oxide, MgO, phosphorus pentoxide, P{sub 2}O{sub 5}, and potassium oxide, K{sub 2}O, accurate determinations are critical. Due to the tonnage per hour, these determinations must be made rapidly and accurately. X-ray fluorescence can thereby satisfy this need for accuracy and also precision. Production of lime is performed by calcining limestone or dolomite in which the industry is generally located and concentrated in the States of Michigan and Pennsylvania. The resulting product is quicklime, CaO, and hydrated lime, Ca(OH){sub 2}. Substantial amounts of quicklime is further processed into calcium carbide in order to produce acetylene gas. In this case, the determination of P{sub 2}O{sub 5} is critical since minor quantities of phosphorus in acetylene gas can cause premature explosions. Other uses for lime are well known in the treatment of water, the paper and pulp industry, and in the steel industry for the production of slag to remove impurities. Dolomitic lime is heavily utilized in the manufacture of magnesite refractories by reacting dolomitic lime with brines from the Michigan Basin to produce magnesium oxide, MgO, and calcium chloride, CaCl{sub 2}. Sample preparation for these materials usually is performed by grinding and pelletizing or fusion with lithium-tetra-borate, Li{sub 2}B{sub 4}O{sub 7}.

  15. The effects of silica fume and hydrated lime on the strength development and durability characteristics of concrete under hot water curing condition

    Directory of Open Access Journals (Sweden)

    Hamza Ali

    2017-01-01

    Full Text Available Sustainability is considered to be highly important for preserving continued industrial growth and human development. Concrete, being the world’s largest manufacturing material comprises cement as an essential binding component for strength development. However, excessive production of cement due to high degree of construction practices around the world frames cement as a leading pollutant of releasing significant amounts of CO2 in the atmosphere. To overcome this environmental degradation, silica fume and hydrated lime are used as partial replacements to cement. This paper begins with the examination of the partial replacement levels of hydrated lime and silica fume in concrete and their influence on the mechanical properties and durability characteristics of concrete. The effect of hot water curing on concrete incorporated with both silica fume and hydrated lime is also investigated in this paper. The results reported in this paper show that the use of silica fume as a partial replacement material improved both the mechanical properties and durability characteristics of concrete due to the formation of calcium silica hydrate crystals through the pozzolanic reaction. Although the hydrated lime did not significantly contribute in the development of strength, its presence enhanced the durability of concrete especially at long-term. The results also showed that hot water curing enhanced the strength development of concrete incorporated with silica fume due to the accelerated rate of both the hydration and pozzolanic reaction that takes place between silica fume and calcium hydroxide of the cement matrix particularly at early times. The results reported in this paper have significant contribution in the development of sustainable concrete. The paper does not only address the use of alternative binders as a partial replacement material in concrete but also suggest proper curing conditions for the proposed replacement materials. These practices

  16. Preparation of a new sorbent with hydrated lime and blast furnace slag for phosphorus removal from aqueous solution.

    Science.gov (United States)

    Gong, Guozhuo; Ye, Shufeng; Tian, Yajun; Wang, Qi; Ni, Jiandi; Chen, Yunfa

    2009-07-30

    The removal of dissolvable inorganic phosphate (H(2)PO(4)(-)) by sorbents prepared from hydrated lime (HL) and blast furnace slag (BFS) was fundamentally studied by an orthogonal experiment design. Based on statistic analysis, it is revealed that the weight ratio of BFS/HL is the most significant variable, and an optimized preparation condition is figured out. With the increase of HL content, the adsorption capacity increases, suggesting that the HL plays the important role in the removal process in the gross. However, in the lower HL content, it is interesting that the adsorption capacity of as-prepared sorbents exceed the sum of the capacities of the same ratio of BFS and HL. The further analysis indicate the excess capacities linearly depend on the specific surface area of sorbents, suggesting that the removal of H(2)PO(4)(-) is closely related with the microstructure of sorbents in the lower HL content, according to the characterization with SEM, XRD and pore analysis. Additionally, an adsorption model and kinetic are discussed in this paper.

  17. Comparative evaluation of aerial lime mortars for architectural conservation

    OpenAIRE

    Faria, Paulina; Henriques, Fernando M.A.; Rato, Vasco

    2008-01-01

    Journal of Cultural Heritage 9 (2008) 338-346 International bibliography on conservation usually refers that mortars made with lime putty with long extinction periods behave better than others made with the current dry hydrated limes. In order to evaluate this assess, an experimental study of lime mortars was carried out, using dry hydrated lime and two lime putties. It becomes clear that the use of lime putties with long extinction periods in mortars allow better performances, pa...

  18. Study on the hydration activity of ground dolomite in cementing material%白云石粉在水泥基材料中的水化活性研究

    Institute of Scientific and Technical Information of China (English)

    肖佳; 吴婷; 郭明磊

    2016-01-01

    研究了白云石粉在水泥基材料中的水化活性,分析了白云石粉掺量和细度的影响。研究表明,白云石粉掺量为0~30%时,白云石粉在水泥基材料中的强度贡献率大于零,提高了水泥基材料的比强度;随白云石粉掺量增加,水泥-白云石粉胶凝体系的强度及白云石粉在水泥基材料中的活性指数先增大后减小,白云石粉掺量为5%时均达到峰值。随白云石粉细度增大,水泥-白云石粉胶凝体系强度和比强度及白云石粉在水泥基材料中强度贡献率及活性指数均先增大后减小。白云石粉在水泥基材料中发生了去白云石化反应,阻止钙矾石向单硫型水化硫铝酸钙转化,并反应生成了水化碳铝酸钙(C3A·CaCO3·11H2O)。%The hydration activity of ground dolomite in cement based materials was studied,and the influence of the content and fine-ness of ground dolomite were analyzed.The results show that,when the ground dolomite content is 0~30%, the strength contribution rate of ground dolomite was greater than zero and the ground dolomite improved the specific strength of the cementing materials.The compressive strength of the cement-ground dolomite cementitious system and activity index of ground dolomite in the cementing material increased at first then decreased with the ground dolomite content increasing,which reached the maximum with 5% ground dolomite.The strength and specific strength of the cement-ground dolomite cementitious system increased at first then decreased with the ground dolomite fineness in-creasing,where the activity index and strength contribution rate of ground dolomite in the cementing material showed the same discipline. The calcite formation through a reaction of dedolomitization of the ground dolomite in the cementing material and inhibited the transfor-mation of ettringite to AFm,caused the formation of C3A·CaCO3·11H2O.

  19. Evaluation of Ohio fly ash/hydrated lime slurries and Type 1 cement sorbent slurries in the U.C. Pilot spray dryer facility. Final report, September 1, 1993--August 31, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Keener, T.C.; Khang, S.J.; Meyers, G.R. [Cincinnati Univ., OH (United States)

    1995-02-01

    The objectives of this year`s work included an evaluation of the performance of fly ash/hydrated lime as well as hydrated cement sorbents for spray drying adsorption (SDA) of SO{sub 2} from a simulated high-sulfur flue gas. These sorbents were evaluated for several different hydration methods, and under different SDA operating conditions. In addition, the physical properties of surface area and porosity of the sorbents was determined. The most reactive fly ash/hydrated lime sorbent studied was prepared at room temperature with milled fly ash. Milling fly ash prior to hydration with lime did have a beneficial effect on calcium utilization. No benefit in utilization was experienced either by hydrating the slurries at a temperature of 90{degrees}C as compared to hydration at room temperature, or by increasing hydration time. While the surface areas varied greatly from sorbent to sorbent, the pore size distributions indicated ``ink bottle`` pores with surface porosity on the order of 0.5 microns. No correlation could be drawn between the surface area of the sorbents and calcium utilization. These results suggest that the composition of the resulting sorbent might be more important than its surface area. The most effective sorbent studied this year was produced by hydrating cement for 3 days at room temperature. This sorbent provided a removal efficiency and a calcium utilization over 25 percent higher than baseline results at an approach to saturation temperature of 30{degrees}F and a stoichiometric ratio of 0.9. A maximum SO{sub 2} removal efficiency of about 90 percent was experienced with this sorbent at an approach to saturation temperature of 20{degrees}F.

  20. Local development of affordable lime in southern Africa

    OpenAIRE

    1997-01-01

    Lime is an important and versatile chemical used in a wide range of applications. The term lime, which is strictly calcium oxide (CaO), is applied to a range of products arising from the processing of limestone and dolomite. Many less developed countries do not have adequate lime production and this leads to problems associated with under-utilisation of lime. In particular, insufficient application of agricultural lime (aglime) can lead to soil acidification, with associated aluminium / manga...

  1. Dolomitization and Uniformitarianism

    Science.gov (United States)

    Zenger, Donald H.

    1972-01-01

    Reviews research of the past 15 years related to the occurrence of stratigraphic dolomite, confronting especially the main dolomite issue - the discrepancy between the amount of modern and ancient dolomite. (PR)

  2. Microbial dolomite crusts from the carbonate platform off western India

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, V.P.; Kessarkar, P.M.; Krumbein, W.E.; Krajewski, K.P.; Schneider, R.J.

    -water dolomites involve pumping of © 2003 International Association of Sedimentologists large volumes of normal sea water or brines through the sediments (Adams & Rhodes, 1960; Carballo et 01., 1987; Vahrenkamp et 01., 1991; Swart & Melim, 2000; Melim & Scholle... ancient dolomite depDsits are associated with stromatolitic lime stones or organic-rich sediments (Valdiya, 1972; Gebelian & Hoffman, 1973; Montanez & Read, 1992; Montanez & Osleger, 1993; Wright, 1997), suggesting a possible mechanistic link to micro...

  3. A new lime material for container substrates

    Science.gov (United States)

    The primary component in greenhouse potting substrates is sphagnum peatmoss. Substrate solution pH of non-amended peatmoss ranges from 4.0 to 4.5. Ideal pH for most greenhouse floriculture crops ranges from 5.8 to 6.2. Dolomitic lime is most often used to elevate substrate pH in peatmoss-based me...

  4. Antiviral activities of heated dolomite powder.

    Science.gov (United States)

    Motoike, Koichi; Hirano, Shozo; Yamana, Hideaki; Onda, Tetsuhiko; Maeda, Takayoshi; Ito, Toshihiro; Hayakawa, Motozo

    2008-12-01

    The effect of the heating conditions of dolomite powder on its antiviral activity was studied against the H5N3 avian influenza virus. Calcium oxide (CaO) and magnesium oxide (MgO), obtained by the thermal decomposition of dolomite above 800 degrees C, were shown to have strong antiviral activity, but the effect was lessened when the heating temperature exceeded 1400 degrees C. Simultaneous measurement of the crystallite size suggested that the weakening of the activity was due to the considerable grain growth of the oxides. It was found that the presence of Mg in dolomite contributed to the deterrence of grain growth of the oxides during the heating process. Although both CaO and MgO exhibited strong antiviral activity, CaO had the stronger activity but quickly hydrated in the presence of water. On the other hand, the hydration of MgO took place gradually under the same conditions. Separate measurements using MgO and Mg(OH)2 revealed that MgO had a higher antiviral effect than Mg(OH)2. From the overall experiments, it was suggested that the strong antiviral activity of dolomite was related to the hydration reaction of CaO.

  5. Lime Pretreatment

    Science.gov (United States)

    Sierra, Rocio; Granda, Cesar Benigno; Holtzapple, Mark T.

    Lime pretreatment has proven to be a useful method for selectively reducing the lignin content of lignocellulosic biomass without significant loss in carbohydrates, thus realizing an important increase in biodigestibility. In lime pretreatment, the biomass is pretreated with calcium hydroxide and water under different conditions of temperature and pressure. It can be accomplished in one of three fashions: (1) short-term pretreatment that lasts up to 6 h, requires temperatures of 100-160°C, and can be applied with or without oxygen (pressure ~200 psig); (2) long-term pretreatment taking up to 8 weeks, requiring only 55-65°C, and capable of running with or without air (atmospheric pressure); and (3) simple pretreatment requiring 1 h in boiling water, without air or oxygen. Nonoxidative conditions are effective at low lignin contents (below ~18% lignin), whereas oxidative conditions are required for high lignin contents (above ~18% lignin).

  6. Location of quarries of magnesian lime used as raw material of Roman plasters in western Lombardy (Italy

    Directory of Open Access Journals (Sweden)

    Roberto Bugini

    2017-01-01

    Full Text Available Lime as building material was widely diffused in Roman architecture of western Lombardy. The presence of magnesite (magnesium carbonate was detected in painted plasters coming from roman sites of Milano: magnesite indicates the use of dolomite to make the lime. Dolomite rocks widely outcrop in the Lombard Prealps: light grey dolomites and dolomitic limestones (Dolomia del Salvatore, Ladinian-Anisian; grey dolomites, sometimes with cyclothemes (Dolomia Principale, Norian. There is no evidence of Roman lime quarries or kilns in this area; the Romans probably exploited the same dolomite outcrops, located along the eastern shore of lake Maggiore, where lime was produced from the Middle Ages onwards. The glacio-fluvial deposits of the middle course of the river Adda (cobbles, pebbles of siliceous limestone together with limestone and dolomite outcropping in the river basin were another medieval and modern source of raw material, mainly to make a moderately hydraulic lime (called “calce forte”, but this kind of lime is lacking in Roman plasters.

  7. Soil Stabilization Using Lime: Advantages, Disadvantages and Proposing a Potential Alternative

    OpenAIRE

    Ibtehaj Taha Jawad; Mohd Raihan Taha; Zaid Hameed Majeed; Tanveer A Khan

    2014-01-01

    This study is an overview of previous studies on lime (quick and hydrated) -treated soil. Lime is the oldest traditional stabilizer used for soil stabilization. The mechanism of soil-lime treatment involves cation exchange, which leads to the flocculation and agglomeration of soil particles. The high pH environment then causes a pozzolanic reaction between the free Ca+2 cations and the dissolved silica and alumina. Lime-treated soil effectively increases the strength, durability and workabili...

  8. 海水淡化浓盐水石灰法制备氢氧化镁的研究%Research on Preparation of Magnesium Hydrate Through Lime Method with Concentrated Saltwater Obtained from Seawater Desalination

    Institute of Scientific and Technical Information of China (English)

    陈侠; 马俊涛; 周秀云; 于博

    2012-01-01

    The experiment study on the process conditions of preparation of magnesium hydrate through lime method, using the concentrated slatwater obtained from Seawater Desalination as raw material. According to the single factor and orthogonal tests, the effects of reaction aging time, molar ratio of calcium hydroxide and magnesium ions, the flow rate of calcium hydroxide and agitation rate on the purity of magnesium hydrate and calcium content in the production are investigated to optimize the reaction conditions. The results show that the order of the factors is molar ratio of calcium hydroxide and magnesium ions, the flow rate of calcium hydroxide and the reaction aging time follow. The optimal react conditions are: molar ratio of calcium hydroxide and magnesium ions is 0.9, the flow rate of calcium hydroxide is 10 x 10 "3 mol/min, and the reaction aging time is 120 min.%以海水淡化获得的浓盐水为原料,进行石灰法制备氢氧化镁的实验研究.通过单因素实验和正交实验,考察了反应陈化时间、Ca(OH)2与Mg2摩尔比、Ca(OH)2加料速率和反应器搅拌速率对氢氧化镁纯度及钙含量的影响,优化了反应条件.实验结果表明,影响氢氧化镁纯度及钙含量的各因素大小依次为:Ca(OH)2与Mg2摩尔比、Ca(OH)2加料速率、反应陈化时间.并确定了氢氧化镁制备的优化条件为:Ca( OH)2与Mg2+摩尔比0.9、Ca(OH)2的加料速率10 mmol/min,反应陈化时间120 min.

  9. Effects of dicyandiamide and dolomite application on N2O emission from an acidic soil.

    Science.gov (United States)

    Shaaban, Muhammad; Wu, Yupeng; Peng, Qi-an; Lin, Shan; Mo, Yongliang; Wu, Lei; Hu, Ronggui; Zhou, Wei

    2016-04-01

    Soil acidification is a major problem for sustainable agriculture since it limits productivity of several crops. Liming is usually adopted to ameliorate soil acidity that can trigger soil processes such as nitrification, denitrification, and loss of nitrogen (N) as nitrous oxide (N2O) emissions. The loss of N following liming of acidic soils can be controlled by nitrification inhibitors (such as dicyandiamide). However, effects of nitrification inhibitors following liming of acidic soils are not well understood so far. Here, we conducted a laboratory study using an acidic soil to examine the effects of dolomite and dicyandiamide (DCD) application on N2O emissions. Three levels of DCD (0, 10, and 20 mg kg(-1); DCD0, DCD10, and DCD20, respectively) were applied to the acidic soil under two levels of dolomite (0 and 1 g kg(-1)) which were further treated with two levels of N fertilizer (0 and 200 mg N kg(-1)). Results showed that N2O emissions were highest at low soil pH levels in fertilizer-treated soil without application of DCD and dolomite. Application of DCD and dolomite significantly (P ≤ 0.001) reduced N2O emissions through decreasing rates of NH4 (+)-N oxidation and increasing soil pH, respectively. Total N2O emissions were reduced by 44 and 13% in DCD20 and dolomite alone treatments, respectively, while DCD20 + dolomite reduced N2O emissions by 54% when compared with DCD0 treatment. The present study suggests that application of DCD and dolomite to acidic soils can mitigate N2O emissions.

  10. Geology of the Dolomites

    Institute of Scientific and Technical Information of China (English)

    AlfonsoBosellini; PieroGianolla; MarcoStefani

    2003-01-01

    The Dolomites region is a spectacularly exposed portion of the Southern Alps, a northern Italian chain derived from the comparatively gentle deformation of the Tethyan passive continental margin of Adria. The regionhad an active Permo-Jurassic tectono-magmatic evolu-tion, leading from Permian magmatism, through a Mid-die Triassic episode offast subsidence and volcanism, to the Jurassic oceanic break-up. Although the sedimentary succession ranges in age from Middle Permian to Creta-ceous, the geological landscape is largely dominated by the majestic Triassic carbonates, making the area a clas-sical one for the early Mesozoic stratigraphy. Particu-larly noteworthy are the Anisian to Carnian carbonate platforms, recording an evolution from regional muddy banks to isolated high-relief builduos. The hlline of the various basins and the development of a last generation of regional peritidal platform followed. The carbonate platforms of the Dolomites bear witness to a remarkable set of changes in the carbonate production and to signif-icant palaeoclimatic fluctuations,from arid to moist con-difions and vice versa; a great range of margin and slope depositional styles is therefore recorded. Alpine tectonic shortening strongly affected the area, with a first Eocenede formation, followed by later Neogene overthrusting and strike-slip movements.

  11. Soil Stabilization Using Lime: Advantages, Disadvantages and Proposing a Potential Alternative

    Directory of Open Access Journals (Sweden)

    Ibtehaj Taha Jawad

    2014-07-01

    Full Text Available This study is an overview of previous studies on lime (quick and hydrated -treated soil. Lime is the oldest traditional stabilizer used for soil stabilization. The mechanism of soil-lime treatment involves cation exchange, which leads to the flocculation and agglomeration of soil particles. The high pH environment then causes a pozzolanic reaction between the free Ca+2 cations and the dissolved silica and alumina. Lime-treated soil effectively increases the strength, durability and workability of the soil. Such treatment also improves soil compressibility. A fluctuation behavior was observed on the influence of lime on soil permeability. However, the factors affecting the permeability of the soil-lime mixture should be extensively studied. Nonetheless, lime treatment has a number of inherent disadvantages, such as carbonation, sulfate attack and environment impact. Magnesium oxide/hydroxide are thus proposed as a suitable alternative stabilizer to overcome at least some of the disadvantages of using lime in soil stabilization.

  12. Nitrosomonas europaea-like bacteria detected as the dominant b-subclass Proteobacteria ammonia oxidisers in reference and limed acid forest soils

    NARCIS (Netherlands)

    Carnol, M.; Kowalchuk, G.A.; De Boer, W.

    2002-01-01

    Net nitrification in intact soil cores and the community of ammonia-oxidising bacteria were studied in acid Norway spruce (Picea abies (L.) Karst) and sessile oak (Quercus petraea (Matt. Lieb.)) soils (Haute Ardenne, east Belgium) 18 months after treatment with 5tha1 dolomite lime. Liming caused a s

  13. Some studies on the reaction between fly ash and lime

    Indian Academy of Sciences (India)

    A Basumajumdar; A K Das; N Bandyopadhyay; S Maitra

    2005-04-01

    The reaction between fly ash (FA) and lime is extensively exploited for the manufacture of building bricks, blocks and aggregates. To get a better idea of this reaction, FA from different sources were mixed in different ratios with lime and compacted. The compacts were treated both by ordinary water and hydrothermal curing to promote lime bearing hydrate bond formation e.g. CaO–SiO2–H2O (C–S–H), CaO–Al2O3–H2O (C–A–H) etc. The decrease in free lime content in these compacts was measured as a function of curing time and curing process. This drop in this content was correlated to the chemical composition of the fly ashes. The mathematical relationships between free lime remaining in the compacts after its maximum decrease in concentration and lime binding modulus (a ratio between the amount of added lime and the total amount of lime binding constituents present in FA) for both types of curing were developed. Further, the rate of decrease in free CaO content under both types of curing conditions was compared from kinetic study. From this study the orders of the reactions and rate constants were found out.

  14. Dolomitization of Carbonate Periplatform Deposit,Machari Formation (Middle to Late Cambrian),Korea

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@The petrography, the geochemistry and the burial history all constrain the origin and modification history of dolomites in an ancient periplatform carbonate slope deposit,the Machari Formation (late Miclclle to early Late Cambrian),Korea. The formation is mainly composed of rhythmic bedding. laminated to bedded lime mudstone alternating with argillaceous lime mudstone. The rhythmic bedding is a product of the deposition of offshore periplatform ooze and hemipelagic clay on a periplatform slope. This formation also shows minor and intermittent influx of other lithofacies including the bioclastic-peloidal packstone, peloidal wackestone, and intraclasts deposited as turbidites. Five types of dolomite occur in the Machari Formation, whose occurrence.texture and geochemistry provide an insight into origin and modification history.

  15. Influence Parameters on Properties of Dolomite Bricks Containing Different Bonding Systems

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Pitch and tar bonded dolomite bricks are extensively used in ladles and converters for long time because of their superior properties such as: steel melt refining, easy production as well as low production cost. Recently,resin bonded dolomite bricks are presented for using in steel plants. Generally, quality and final cost of steels are affected by properties of refractories especially dolomite bricks. Therefore, recognition of influence parameters on dolomite refractory properties is very important.In this study, the effects of tar and resin as bonding systems, and addition of graphite ( 2wt% ) on the properties of dolomite refractory bricks have been investigated.Properties such as: density and porosity, cold crushing strength, hydration time and depth of slag penetration have been studied. Results show that the bonding systems and graphite have a great effect on the mentioned properties especially cold crushing strength and hydration time. In addition to their low rate of pollution, resin bonded dolomite bricks show higher performance with proper technical specifications.

  16. Rootstocks for 'Tahiti' lime

    Directory of Open Access Journals (Sweden)

    Stenzel Neusa Maria Colauto

    2004-01-01

    Full Text Available The 'Tahiti' lime (Citrus latifolia Tanaka is an important commercial citrus cultivar in Brazil. 'Rangpur' lime has being used as its main rootstock, but it is susceptible to root rot caused by Phytophthora, reducing tree longevity. An experiment was set up in a randomized block design, with three trees per plot of each rootstock and four replicates, and run for 12 years, aiming to compare the performance of 'IAC-5 Tahiti' lime, budded on 'Rangpur' lime (Citrus limonia Osb.; 'C-13' citrange (Citrus sinensis (L. Osb. × Poncirus trifoliata (L. Raf.; 'African' rough lemon (Citrus jambhiri Lush.; 'Volkamer' lemon (Citrus volkameriana Ten. & Pasq.; trifoliate orange (Poncirus trifoliata (L. Raf.; 'Sunki' mandarin (Citrus sunki Hort. ex Tan. and 'Cleopatra' mandarin (Citrus reshni Hort. ex Tan.. Eleven years after the establishment of the orchard, trees with the greatest canopy development were budded on 'C-13' citrange and 'African' rough lemon, and both differed significantly from trees budded on trifoliate orange, 'Sunki' and 'Cleopatra' mandarins, which presented the smallest canopy development. Trees budded on 'Rangpur' lime and 'C-13' citrange had the highest cumulative yields, and were different from trees budded on trifoliate orange, 'Cleopatra' and 'Sunki' mandarins. There was no rootstock effect on mean fruit weight and on the total soluble solid/acid ratio in the juice. The 'Rangpur' lime and the 'Cleopatra' mandarin rootstocks reduced longevity of plants.

  17. Plant Life of the Dolomites

    Directory of Open Access Journals (Sweden)

    Rob Brooker

    2015-02-01

    Full Text Available Reviewed: Plant Life of the Dolomites. By Erika Pignatti and Sandro Pignatti. Heidelberg, Germany: Springer, 2014. xxxvii + 769 pp. US$ 209.00, £ 135.00, J 149.95. Also available as an e-book. ISBN 978-3-642-31042-3.

  18. Thermal decomposition of natural dolomite

    Indian Academy of Sciences (India)

    S Gunasekaran; G Anbalagan

    2007-08-01

    Thermal decomposition behaviour of dolomite sample has been studied by thermogravimetric (TG) measurements. Differential thermal analysis (DTA) curve of dolomite shows two peaks at 777.8°C and 834°C. The two endothermic peaks observed in dolomite are essentially due to decarbonation of dolomite and calcite, respectively. The TG data of the decomposition steps have also been analysed using various differential, difference-differential and integral methods, viz. Freeman–Carroll, Horowitz–Metzger, Coats–Redfern methods. Values of activation entropy, Arrhenius factor, and order of reaction have been approximated and compared. Measured activation energies vary between 97 and 147 kJ mol-1. The large fluctuation in activation energy is attributed to the presence of impurities such as SiO2, Al2O3, Fe2O3, Cl- etc in the samples. FTIR and XRD analyses confirm the decomposition reaction. SEM observation of the heat-treated samples at 950°C shows cluster of grains, indicating the structural transformation.

  19. Microbial Response to Soil Liming of Damaged Ecosystems Revealed by Pyrosequencing and Phospholipid Fatty Acid Analyses

    Science.gov (United States)

    Narendrula-Kotha, Ramya; Nkongolo, Kabwe K.

    2017-01-01

    Aims To assess the effects of dolomitic limestone applications on soil microbial communities’ dynamics and bacterial and fungal biomass, relative abundance, and diversity in metal reclaimed regions. Methods and Results The study was conducted in reclaimed mining sites and metal uncontaminated areas. The limestone applications were performed over 35 years ago. Total microbial biomass was determined by Phospholipid fatty acids. Bacterial and fungal relative abundance and diversity were assessed using 454 pyrosequencing. There was a significant increase of total microbial biomass in limed sites (342 ng/g) compared to unlimed areas (149 ng/g). Chao1 estimates followed the same trend. But the total number of OTUs (Operational Taxonomic Units) in limed (463 OTUs) and unlimed (473 OTUs) soil samples for bacteria were similar. For fungi, OTUs were 96 and 81 for limed and unlimed soil samples, respectively. Likewise, Simpson and Shannon diversity indices revealed no significant differences between limed and unlimed sites. Bacterial and fungal groups specific to either limed or unlimed sites were identified. Five major bacterial phyla including Actinobacteria, Acidobacteria, Chloroflexi, Firmicutes, and Proteobacteria were found. The latter was the most prevalent phylum in all the samples with a relative abundance of 50%. Bradyrhizobiaceae family with 12 genera including the nitrogen fixing Bradirhizobium genus was more abundant in limed sites compared to unlimed areas. For fungi, Ascomycota was the most predominant phylum in unlimed soils (46%) while Basidiomycota phylum represented 86% of all fungi in the limed areas. Conclusion Detailed analysis of the data revealed that although soil liming increases significantly the amount of microbial biomass, the level of species diversity remain statistically unchanged even though the microbial compositions of the damaged and restored sites are different. Significance and Impact of the study Soil liming still have a significant

  20. Influence of ameliorating soil acidity with dolomite on the priming of soil C content and CO2 emission.

    Science.gov (United States)

    Shaaban, Muhammad; Wu, Lei; Peng, Qi-An; van Zwieten, Lukas; Chhajro, Muhammad Afzal; Wu, Yupeng; Lin, Shan; Ahmed, Muhammad Mahmood; Khalid, Muhammad Salman; Abid, Muhammad; Hu, Ronggui

    2017-02-21

    Lime or dolomite is commonly implemented to ameliorate soil acidity. However, the impact of dolomite on CO2 emissions from acidic soils is largely unknown. A 53-day laboratory study was carried out to investigate CO2 emissions by applying dolomite to an acidic Acrisol (rice-rapeseed rotation [RR soil]) and a Ferralsol (rice-fallow/flooded rotation [RF soil]). Dolomite was dosed at 0, 0.5, and 1.5 g 100 g(-1) soil, herein referred to as CK, L, and H, respectively. The soil pH(H2O) increased from 5.25 to 7.03 and 7.62 in L and H treatments of the RR soil and from 5.52 to 7.27 and 7.77 in L and H treatments of the RF soil, respectively. Dolomite application significantly (p ≤ 0.001) increased CO2 emissions in both RR and RF soils, with higher emissions in H as compared to L dose of dolomite. The cumulative CO2 emissions with H dose of dolomite were greater 136% in the RR soil and 149% in the RF soil as compared to CK, respectively. Dissolved organic carbon (DOC) and microbial biomass carbon (MBC) increased and reached at 193 and 431 mg kg(-1) in the RR soil and 244 and 481 mg kg(-1) in the RF soil by H treatments. The NH4(-)-N and NO3(-)-N were also increased by dolomite application. The increase in C and N contents stimulated microbial activities and therefore higher respiration in dolomite-treated soil as compared to untreated. The results suggest that CO2 release in dolomite-treated soils was due to the priming of soil C content rather than chemical reactions.

  1. Effects of liming on forage availability and nutrient content in a forest impacted by acid rain.

    Directory of Open Access Journals (Sweden)

    Sarah E Pabian

    Full Text Available Acidic deposition and subsequent forest soil acidification and nutrient depletion can affect negatively the growth, health and nutrient content of vegetation, potentially limiting the availability and nutrient content of forage for white-tailed deer (Odocoileus virginianus and other forest herbivores. Liming is a mitigation technique that can be used to restore forest health in acidified areas, but little is known about how it affects the growth or nutrient content of deer forage. We examined the effects of dolomitic limestone application on the growth and chemical composition of understory plants in an acidified forest in central Pennsylvania, with a focus on vegetative groups included as white-tailed deer forage. We used a Before-After-Control-Impact study design with observations 1 year before liming and up to 5 years post-liming on 2 treated and 2 untreated 100-ha sites. Before liming, forage availability and several nutrients were below levels considered optimal for white-tailed deer, and many vegetative characteristics were related to soil chemistry. We observed a positive effect of liming on forb biomass, with a 2.7 fold increase on limed sites, but no biomass response in other vegetation groups. We observed positive effects of liming on calcium and magnesium content and negative effects on aluminum and manganese content of several plant groups. Responses to liming by forbs and plant nutrients show promise for improving vegetation health and forage quality and quantity for deer.

  2. Efluent treatment with dolomite mining

    OpenAIRE

    Romero Baylón, Alfonso; UNMSM; Flores Chávez, Silvana; UNMSM; Arévalo, Walter; UNMSM

    2014-01-01

    The article shows a methodology for acid water treatment, through the remediation of effluents from the mining industry, based on the use of treated dolomite, which reduces the concentrations of dissolved heavy metal ions in metallurgical and mining effluent to reducing high levels of heavy metals, which are indicators of improved water quality of industrial wastes, mainly from metallurgical processes concentrator plants. This treatment technique solves the problem of effluent generation with...

  3. Enrico Fermi and the Dolomites

    Energy Technology Data Exchange (ETDEWEB)

    Battimelli, Giovanni, E-mail: giovanni.battimelli@uniroma1.it; Angelis, Alessandro de, E-mail: alessandro.de.angelis@cern.ch

    2014-11-15

    Summer vacations in the Dolomites were a tradition among the professors of the Faculty of Mathematical and Physical Sciences at the University of Roma since the end of the XIX century. Beyond the academic walls, people like Tullio Levi-Civita, Federigo Enriques and Ugo Amaldi sr., together with their families, were meeting friends and colleagues in Cortina, San Vito, Dobbiaco, Vigo di Fassa and Selva, enjoying trekking together with scientific discussions. The tradition was transmitted to the next generations, in particular in the first half of the XX century, and the group of via Panisperna was directly connected: Edoardo Amaldi, the son of the mathematician Ugo sr., rented at least during two summers, in 1925 and in 1949, and in the winter of 1960, a house in San Vito di Cadore, and almost every year in the Dolomites; Enrico Fermi was a frequent guest. Many important steps in modern physics, in particular the development of the Fermi-Dirac statistics and the Fermi theory of beta decay, are related to scientific discussions held in the region of the Dolomites.

  4. Enrico Fermi and the Dolomites

    Science.gov (United States)

    Battimelli, Giovanni; de Angelis, Alessandro

    2014-11-01

    Summer vacations in the Dolomites were a tradition among the professors of the Faculty of Mathematical and Physical Sciences at the University of Roma since the end of the XIX century. Beyond the academic walls, people like Tullio Levi-Civita, Federigo Enriques and Ugo Amaldi sr., together with their families, were meeting friends and colleagues in Cortina, San Vito, Dobbiaco, Vigo di Fassa and Selva, enjoying trekking together with scientific discussions. The tradition was transmitted to the next generations, in particular in the first half of the XX century, and the group of via Panisperna was directly connected: Edoardo Amaldi, the son of the mathematician Ugo sr., rented at least during two summers, in 1925 and in 1949, and in the winter of 1960, a house in San Vito di Cadore, and almost every year in the Dolomites; Enrico Fermi was a frequent guest. Many important steps in modern physics, in particular the development of the Fermi-Dirac statistics and the Fermi theory of beta decay, are related to scientific discussions held in the region of the Dolomites.

  5. Dolomite application to acidic soils: a promising option for mitigating N2O emissions.

    Science.gov (United States)

    Shaaban, Muhammad; Peng, Qi-An; Hu, Ronggui; Wu, Yupeng; Lin, Shan; Zhao, Jinsong

    2015-12-01

    Soil acidification is one of the main problems to crop productivity as well as a potent source of atmospheric nitrous oxide (N2O). Liming practice is usually performed for the amelioration of acidic soils, but the effects of dolomite application on N2O emissions from acidic soils are still not well understood. Therefore, a laboratory study was conducted to examine N2O emissions from an acidic soil following application of dolomite. Dolomite was applied to acidic soil in a factorial design under different levels of moisture and nitrogen (N) fertilizer. Treatments were as follows: dolomite was applied as 0, 1, and 2 g kg(-1) soil (named as CK, L, and H, respectively) under two levels of moisture [i.e., 55 and 90 % water-filled pore space (WFPS)]. All treatments of dolomite and moisture were further amended with 0 and 200 mg N kg(-1) soil as (NH4)2SO4. Soil properties such as soil pH, mineral N (NH4 (+)-N and NO3 (-)-N), microbial biomass carbon (MBC), dissolved organic carbon (DOC), and soil N2O emissions were analyzed throughout the study period. Application of N fertilizer rapidly increased soil N2O emissions and peaked at 0.59 μg N2O-N kg(-1) h(-1) under 90 % WFPS without dolomite application. The highest cumulative N2O flux was 246.32 μg N2O-N kg(-1) under 90 % WFPS without dolomite addition in fertilized soil. Addition of dolomite significantly (p ≤ 0.01) mitigated N2O emissions as soil pH increased, and H treatment was more effective for mitigating N2O emissions as compared to L treatment. The H treatment decreased the cumulative N2O emissions by up to 73 and 67 % under 55 and 90 % WFPS, respectively, in fertilized soil, and 60 and 68 % under 55 and 90 % WFPS, respectively, in unfertilized soil when compared to those without dolomite addition. Results demonstrated that application of dolomite to acidic soils is a promising option for mitigating N2O emissions.

  6. Mineralogical correlation between primary and replacement dolomites

    Institute of Scientific and Technical Information of China (English)

    黄志诚; 杨守业; 陈智娜

    1997-01-01

    Primary dolostones occur in the Upper Sinian Dengying Formation. Based on mineralogieal study the indicators for correlation between the primary dolomites which are not influenced by the diagenesis and the replacement dolomites of different periods have been obtained. It is shown that the primary dolomites are characterized by crystal forms precipitated and deposited directly from sea water, stable and homogeneous distribution of Mg and Ca, ideal chemical composition, regular modulated microstructures, low positive δ13C and low negative δ18O.

  7. Enrico Fermi and the Dolomites

    CERN Document Server

    Battimelli, Giovanni

    2014-01-01

    Summer vacations in the Dolomites were a tradition among the professors of the Faculty of Mathematical and Physical Sciences at the University of Roma since the end of the XIX century. Beyond the academic walls, people like Tullio Levi-Civita, Federigo Enriques and Ugo Amaldi sr., together with their families, were meeting friends and colleagues in Cortina, San Vito, Dobbiaco, Vigo di Fassa and Selva, enjoying trekking together with scientific discussions. The tradition was transmitted to the next generations, in particular in the first half of the XX century, and the group of via Panisperna was directly connected: Edoardo Amaldi, the son of the mathematician Ugo sr., rented at least during two summers, in 1925 and in 1949, and in the winter of 1960, a house in San Vito di Cadore, and almost every year in the Dolomites; Enrico Fermi was a frequent guest. Many important steps in modern physics, in particular the development of the Fermi-Dirac statistics and the Fermi theory of beta decay, are related to scient...

  8. The Effect of Liming and Fertilization on Yields of Maize and Winter Wheat

    Directory of Open Access Journals (Sweden)

    Ivica Kisić

    2004-09-01

    Full Text Available Effect of different rates of hydrated lime and zeolite tuffs, as lime materials, mineral and organic fertilizers upon the yield of maize and winter wheat grain was studied in an exact field trial set up on Eutric Gleysol, near Karlovac, Central Croatia. The following crops were cultivated during the study period: 1999 and 2001 – maize, 1999/00 and 2001/02 – winter wheat. In the first investigation year, the highest yield of maize grain of 9.78 t ha-1 was achieved with the combination of the higher mineral fertilizer rate and the higher rate of farmyard manure. In the following year, the highest yield of winter wheat grain of 5.85 t ha-1 was achieved with the combination of the higher mineral fertilizer rate and the higher rate of hydrated lime. In the third and fourth investigation years, the highest yields of maize grain (10.05 t ha-1 and wheat (5.48 t ha-1 were recorded for the combination of the higher rates of mineral fertilizers and hydrated lime. The foregoing allows the conclusion that mineral and organic fertilization combined with hydrated lime is the optimal solution for increasing the yields of test crops.

  9. Early Carbonation Behavior of High-volume Dolomite Powder-cement Based Materials

    Institute of Scientific and Technical Information of China (English)

    YANG Huamei; HE zhen; SHAO Yixin

    2015-01-01

    Combined with DTG analysis, X-Ray diffraction analysis (XRD) andfi eld emission scanning electron microscopy analysis (FSEM) affi liated with energy dispersive spectrometer analysis (EDS), the early hydration and carbonation behavior of cement paste compacts incorporated with 30% of dolomite powder at low water to cement ratio (0.15) was investigated. The results showed that early carbonation curing was capable of developing rapid early strength. It is noted that the carbonation duration should be strictly controlled otherwise subsequent hydration might be hindered. Dolomite powder acted as nuclei of crystallization, resulting in acceleration of products formation and refi nement of products crystal size. Therefore, as for cement-based material, it was found that early carbonation could reduce cement dosages to a large extent and promote rapid strength gain resulting from rapid formation of products, supplemental enhancement due to water release in the reaction of carbonation, and formation of nanometer CaCO3 skeleton network at early age.

  10. LIME REQUIREMENT DETERMINATION AND LIMING IMPACT ON SOIL NUTRIENT STATUS

    Directory of Open Access Journals (Sweden)

    Krunoslav Karalić

    2010-06-01

    Full Text Available The aim of conducted research was to determine the influence of liming, mineral and organic fertilization on soil chemical properties and nutrient availability in the soil, yield height and mineral composition of alfalfa. Results were used to create regression models for prediction of liming impact on soil chemical properties. Liming and fertilization experiment was sat up in 20 L volume plastic pots with two types of acid soils with different texture from two sites. Ten liming and fertilization treatments were applied in four repetitions. Lime treatments increased soil pH values and decreased hydrolytic acidity. Mineral and organic fertilization affected additional soil acidification. Application of lime intensified mineralization and humus decomposition, while organic fertilization raised humus content. The results showed significant increase of AL-P2O5 and K2O availability. The treatments increased soil Ca concentrations, but at the same time decreased exchangeable Mg concentrations. Soil pH increase resulted in lower Fe, Mn, Zn and Cu availability. Soil CEC was increased by applied treatments. Lime rates increased number and height of alfalfa plants, as well as yield of leaf, stalk increased concentrations of N, P, K and Ca in alfalfa leaf and stalk, but decreased leaf Mg and Fe, Mn, Zn and Cu concentrations. Regression computer models predicted with adequate accuracy P, Fe, Mn, Zn and Cu availability and final pH value as a result of liming and fertilization impact.

  11. Potassium supply to cotton roots as affected by potassium fertilization and liming

    Directory of Open Access Journals (Sweden)

    Rosolem Ciro Antonio

    2003-01-01

    Full Text Available Cotton (Gossypium hirsutum is known to have a high requirement for K and to be very sensitive to low soil pH. Most of K reaches plant roots by diffusion in the soil. As K interacts with Ca and Mg, liming can interfere in K movement in the soil, affecting eventually the plant nutrition. The objective of this work was to study the effect of dolomitic lime and 0, 15, 30, 45 and 60 g kg-1 of K on the supply of K to cotton roots. Cotton plants were grown up to 40 days in 5 L pots containing a Dark Red Latosol (Typic Haplusthox with 68% and 16% of sand and clay, respectively. There was an increase in dry matter yields and in K accumulation due to K fertilization. Root interception of soil K was also increased by K application, but was not affected by lime. Mass flow and diffusion increased linearly with K levels up to 60 mg kg-1, in pots with lime. In pots without lime the amount of K reaching the roots by diffusion increased up to 45 mg kg-1, but decreased at the highest K level. Accordingly, there was more K reaching the roots through mass flow at the highest K level. This happened because there were more fine roots in pots without lime, at the highest K level. As the roots grew closer, there was a stronger root competition leading to a decrease in the amount of K diffused to cotton roots.

  12. First description of Phanerozoic radiaxial fibrous dolomite

    Science.gov (United States)

    Richter, D. K.; Heinrich, F.; Geske, A.; Neuser, R. D.; Gies, H.; Immenhauser, A.

    2014-05-01

    The petrographic analysis and crystallographic analysis of concretionary carbonate cements ("coal balls") from Carboniferous paralic swamp deposits reveal the presence of (length fast) radiaxial fibrous dolomite (RFD), a fabric not previously reported from the Phanerozoic. This finding is of significance as earlier reports of Phanerozoic radiaxial fibrous carbonates are exclusively of calcite mineralogy. Dolomite concretions described here formed beneath marine transgressive intervals within palustrine coal seams. This is of significance as seawater was arguably the main source of Mg2 + ions for dolomite formation. Here, data from optical microscopy, cathodoluminescence, electron backscattered diffraction, X-ray diffraction and geochemical analyses are presented to characterize three paragenetic dolomite phases and one calcite phase in these concretions. The main focus is on the earliest diagenetic, non-stoichiometric (degree of order: 0.41-0.46) phase I, characterized by botryoidal dolomite constructed of fibres up to 110 μm wide with a systematic undulatory extinction and converging crystal axes. Petrographic and crystallographic evidence clearly qualifies phase I dolomite as radiaxial fibrous. Conversely, fascicular optical fabrics were not found. Carbon-isotope ratios (δ13C) are depleted (between - 11.8 and - 22.1‰) as expected for carbonate precipitation from marine pore-fluids in organic-matter-rich, paralic sediment. Oxygen isotope (δ18O) ratios range between - 1.3 and - 6.0‰. The earliest diagenetic nature of these cements is documented by the presence of ubiquitous, non-compacted fossil plant remains encased in phase I dolomite as well as by the complex zoned luminescence patterns in the crystals and is supported by crystallographic and thermodynamic considerations. It is argued that organic matter, and specifically carboxyl groups, reduced thermodynamic barriers for dolomite formation and facilitated Mg/CaCO3 precipitation. The data shown here

  13. Treating tar sands formations with dolomite

    Energy Technology Data Exchange (ETDEWEB)

    Vinegar, Harold J.; Karanikas, John Michael

    2013-10-15

    A method for treating a karsted formation containing heavy hydrocarbons and dolomite includes providing heat to at least part of one or more karsted layers in the formation from one or more heaters located in the karsted layers. A temperature in at least one of the karsted layers is allowed to reach a decomposition temperature of dolomite in the formation. The dolomite is allowed to decompose and at least some hydrocarbons are produced from at least one of the karsted layers of the formation.

  14. Durability of air lime mortar

    DEFF Research Database (Denmark)

    Nielsen, Anders

    2016-01-01

    This contribution deals with the physical and chemical reasons why pure air lime mortars used in masonry of burned bricks exposed to outdoor climate have shown to be durable from the Middle Ages to our days. This sounds strange in modern times where pure air lime mortars are regarded as weak...

  15. Pityriasis rubra pilaris following exposure to dolomite.

    Science.gov (United States)

    Iraji, Fariba; Siadat, Amir H

    2013-07-01

    In this case report, we present a 30-year-old man who developed pityriasis rubra pilaris (PRP) following exposure to Dolomite. The diagnosis of PRP was confirmed histologically and the patient was successfully treated with acitretin and cyclosporine.

  16. Treating tar sands formations with dolomite

    Energy Technology Data Exchange (ETDEWEB)

    Vinegar, Harold J.; Karanikas, John Michael

    2010-06-08

    Methods for treating a tar sands formation are described herein. The tar sands formation may include dolomite and hydrocarbons. Methods may include providing heat at less than the decomposition temperature of dolomite from one or more heaters to at least a portion of the formation. At least some of the hydrocarbon fluids are mobilized in the formation. At least some of the hydrocarbon fluids may be produced from the formation.

  17. Lactic Acid Fermentation, Urea and Lime Addition: Promising Faecal Sludge Sanitizing Methods for Emergency Sanitation

    NARCIS (Netherlands)

    Anderson, C.; Malambo, D.H.; Gonzalez Perez, M.E.; Nobela, H.N.; De Pooter, L.; Spit, J.; Hooijmans, C.M.; Van de Vossenberg, J.; Greya, W.; Thole, B.; Van Lier, J.B.; Brdjanovic, D.

    2015-01-01

    In this research, three faecal sludge sanitizing methods—lactic acid fermentation, urea treatment and lime treatment—were studied for application in emergency situations. These methods were investigated by undertaking small scale field trials with pit latrine sludge in Blantyre, Malawi. Hydrated lim

  18. Removal of low-concentration phosphorus using a fluidized raw dolomite bed.

    Science.gov (United States)

    Ayoub, George M; Kalinian, Houri

    2006-04-01

    Raw dolomite powder, obtained from dolomitic rocks, was evaluated for its efficiency in removing low concentrations of phosphate present in various water and wastewater matrices. A variety of experimental setups and process variables were tested, in an attempt to determine the optimal scheme (fluidized bed) that will be used to accomplish the objectives of the study. Test influents, including distilled water (DW), synthetic groundwater (SGW), tap water (TW), and sodium-hydroxide (NaOH)-alkalized wastewater treated with liquid bittern (STSE-B) and wastewater treated with lime (STSE-L) were used to assess the effect of influent parameters on the quality of the effluent generated. The adsorptive behavior of dolomite was described by fitting data generated from the study into the Freundlich and Langmuir isotherm models. Regeneration of the dolomite was attempted by the use of an acid (hydrochloric acid), DW, and an alkaline (NaOH). Test results indicate remarkable phosphate removal levels for DW and SGW. Removal levels of 100% were attained, for an average of 307 and 314 bed volumes at inflow concentration levels of 0.28 and 0.34 mg phosphate (PO4)/ L, respectively. Relative adsorption capacities were calculated to be 0.06 and 0.072 mg PO4/g of dolomite, respectively. For TW, STSE-L, and STSE-B, 100% removal before the start of the breakthrough was sustained for averages of 205, 94, and 28 bed volumes at phosphate dosages of 0.34, 0.56, and 0.6 mg PO4/L, respectively. The calculated adsorptive capacities were 0.05, 0.051, and 0.025, respectively. Zeta potential measurement resulted in values of -16.0 mV before treatment and +3.0 mV after complete exhaustion of the bed with PO4-jacked SGW influent, indicating an ionic adsorption of ions of opposite charge to that of the particle surface. Although both the Freundlich and Langmuir isotherms were found to fit the sorption curves, the Langmuir seems to better describe the sorption process in dolomite. Among the three

  19. Effects of Dolomitic Limestone Application on Zinc Speciation in Boreal Forest Smelter-Contaminated Soils.

    Science.gov (United States)

    Hamilton, Jordan G; Farrell, Richard E; Chen, Ning; Reid, Joel; Feng, Renfei; Peak, Derek

    2016-11-01

    Anthropogenic activities at the HudBay Minerals, Inc., Flin Flon (Manitoba, Canada) mining and processing facility have severely affected the surrounding boreal forest ecosystem. Soil contamination occurred via a combination of metal and sulfuric acid deposition and has resulted in forest dieback and ineffective natural recovery. A community-led effort to revegetate areas of the landscape through the application of a dolomitic limestone has been met with varied success. Zinc (Zn) speciation has shown to be closely linked to the presence or absence of an invasive metal-tolerant grass species, with soils being broadly classed into two revegetation response groups. Group I, characterized by the absence of metal-tolerant grasses, and group II, characterized by the presence of metal-tolerant grasses. The systematic approach used to lime areas of the landscape produced a liming chronosequence for each group. This study used a combination of X-ray absorption spectroscopy, X-ray fluorescence mapping, and X-ray diffraction techniques to determine the effect of liming on Zn speciation in these chronosequences. Liming group I soils resulted in the formation of a neo-phase Zn-Al-hydroxy interlayer coprecipitate and subsequent rapid boreal forest revegetation. The effect of liming on Zn speciation on the group II soils resulted in a gradual transition of increasingly stable adsorption species, culminating with a stable Zn-Al-layered double hydroxide precipitate. Boreal forest vegetation has failed to recolonize group II soils during the study. However, the formation of the layered double hydroxide species resulted in a significant reduction in CaCl-extractable Zn. Further research is required to determine how to promote the revegetation of these soils. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  20. Whole-catchment application of dolomite to mitigate episodic acidification of streams induced by sea-salt deposition.

    Science.gov (United States)

    Hindar, Atle

    2005-05-01

    To counteract mobilisation of potentially toxic aluminium (Al) ions to tributaries of salmon rivers, two paired-catchment experiments with terrestrial liming at two sites on the Norwegian west coast were performed. Streams at both sites experienced episodically elevated and potentially toxic Al levels induced by high deposition of sea salts. After application of 2 metric tons ha-1 of 0.2-2 mm dolomite powder at the Brommeland area, stream pH increased above critical levels at about pH=6.0 and remained stable throughout the monitoring period of 3.5 years. Inorganic aluminium decreased to below 20 microg Al L-1, a water quality supposed to be nontoxic for salmon. This was evident also during extreme weather conditions with large relative increases in chloride (Cl) concentrations and negative calculated nonmarine sodium (Na*) concentrations in the streams, indicating potentially toxic sea-salt effects. Cl changed from being closely related to increases in inorganic Al, especially at the Brommeland stream (R2=0.75), to being not important (R2=0.12), but still significant for its variation. At the Hovland area, receiving 1 ton ha-1 of 0-2 mm dolomite powder, stream pH and Al effects were less clear-cut, probably due to the lower dolomite dose. Stream concentrations of both NO3- and SO4(2-) increased significantly due to liming.

  1. A study on engineering characteristics of asphalt concrete using filler with recycled waste lime.

    Science.gov (United States)

    Sung Do, Hwang; Hee Mun, Park; Suk keun, Rhee

    2008-01-01

    This study focuses on determining the engineering characteristics of asphalt concrete using mineral fillers with recycled waste lime, which is a by-product of the production of soda ash (Na(2)CO(3)). The materials tested in this study were made using a 25%, 50%, 75%, and 100% mixing ratio based on the conventional mineral filler ratio to analyze the possibility of using recycled waste lime. The asphalt concretes, made of recycled waste lime, hydrated lime, and conventional asphalt concrete, were evaluated through their fundamental engineering properties such as Marshall stability, indirect tensile strength, resilient modulus, permanent deformation characteristics, moisture susceptibility, and fatigue resistance. The results indicate that the application of recycled waste lime as mineral filler improves the permanent deformation characteristics, stiffness and fatigue endurance of asphalt concrete at the wide range of temperatures. It was also determined that the mixtures with recycled waste lime showed higher resistance against stripping than conventional asphalt concrete. It was concluded from various test results that a waste lime can be used as mineral filler and, especially, can greatly improve the resistance of asphalt concrete to permanent deformation at high temperatures.

  2. Adsorption of arsenate on untreated dolomite powder.

    Science.gov (United States)

    Ayoub, G M; Mehawej, M

    2007-09-05

    Raw dolomite powder was evaluated for its efficiency in adsorbing As(V) from water. An experimental setup comprised of a fluidized dolomite powder bed was used to assess the impact of various test variables on the efficiency of removal of As(V). Test influents including distilled water (DW), synthetic groundwater (SGW) and filtered sewage effluent (FSE) were employed to assess the effect of influent parameters on the adsorption process and the quality of the effluent generated. Dolomite exhibited good As(V) removal levels for distilled water (>92%) and synthetic ground water (>84%) influents at all initial As(V) concentrations tested (0.055-0.600 ppm). Breakthrough of dolomite bed occurred after 45 bed volumes for DW and 20 bed volumes for SGW influents with complete breakthrough taking place at more than 300 bed volumes. As(V) removal from FSE influents was relatively unsuccessful as compared to the DW and SGW influents. Partial removal in the order of 32% from filtered sewage effluent at initial concentration of 0.6 mg/L started at 75 bed volumes and gradually stopped at 165 bed volumes. Varying degrees of As(V) adsorption capacities were observed by the different test influents employed, which indicate that the adsorption of As(V) is adversely affected by competing species, mainly sulfates and phosphates present in the influent. The adsorptive behavior of dolomite was described by fitting data generated from the study into the Langmuir and Freundlich isotherm models. Both models described well the adsorption of dolomite. The average isotherm adsorptive capacity was determined at 5.02 mug/g. Regeneration of the dolomite bed can be achieved with the use of caustic soda solution at a pH of 10.5.

  3. Steam slaking of lime - kinetics and technology. New energy effective lime slaking technology in kraft pulping; Aangslaeckning av kalk - kinetik och teknik. Ny energieffektiv teknik foer slaeckning av mesakalk i sulfatmassaindustrin

    Energy Technology Data Exchange (ETDEWEB)

    Lundqvist, Roland

    2008-06-15

    Lime stone is widely used in chemical recovery for regeneration of white liquor in kraft pulping. Slaked (hydrated) lime is used to convert (causticize) sodium carbonate into sodium hydroxide, whereby lime mud (calcium carbonate) precipitates from the solution. Lime mud is dried and reburned in a lime kiln, where burned lime (calcium oxide) is formed. The circle is closed when lime is slaked (hydrated) in green liquor in an exotherm reaction. Problems with traditional lime burning and slaking methods are that heat recovery is bad and heat is recovered at low temperatures. With the method described in this report there is potential to increase heat recovery in the causticizing plant, and to recover heat at higher temperatures. The forecasted method means that lime is slaked with water vapour, for example combined with an indirect heated lime mud drier and a lime kiln. This project is a follow-up to pilot tests performed in a specific machine equipment at year 2006. The target group is pulp and paper industry using the kraft process. The owner of this new project is Carnot AB and the project is performed inside the Vaermeforsk Program for Pulp and Paper Industry 2006-2008. Partners and advisers in project group have been KTH Energy Processes, CTH Energy and Environment, LTH Chemical Technology, SMA Mineral AB, and reference group from STORA Enso Skoghall, Sodra Cell, M-Real Husum and SCA Packaging Piteaa. The task in this stage has included market investigations and laboratory tests. Contacts have been made with suppliers, preliminary dimensioning of process equipment and budget offers are received. Economic calculations have been made out of the offers. The laboratory tests are done as an examination paper at KTH Energiprocesser on the reactivity of burned lime from kraft lime kiln when it is slaked with water vapour instead of green liquor. The vapour intended to be used is at atmospheric pressure or even down to 0,2 atm. Complementary addition to these laboratory

  4. On the origin and early diagenesis of early Triassic carbonate mud (Dolomites, Italy)

    Science.gov (United States)

    Preto, Nereo; Westphal, Hildegard; Birgel, Daniel; Carampin, Raul; Dal Corso, Jacopo; Gattolin, Giovanni; Montinaro, Alice; Peckmann, Jörn

    2015-04-01

    The earliest Triassic (early Induan) deposits of the Italian Southern Alps are shallow water oolites, and lime-mudstone formed in an open shelf (mid to outer carbonate ramp) sedimentary environment, deposited after the end-Permian extinction that killed all carbonate producers. The origin of these lime-mudstones is thus enigmatic. We used a multidisciplinary petrographic and geochemical approach to identify the origin and early diagenesis of early Triassic lime-mudstones of the Dolomites (Northern Italy). This fine carbonate is made of pitted crystals of microsparite, ~ 25 μm in diameter, exhibiting zonation both in fluorescence and cathodoluminescence. Field and standard petrographic observations exclude an origin from fragmentation or abrasion of carbonate grains. Strontium content, measured in-situ with electron microprobe, has a bimodal distribution with values locally as high as > 4000 ppm. Lipid biomarker analysis revealed molecular fossils of bacteria (terminally-branched alkanes, hopanes, and scarce methylhopanes) along with compounds of low source specificity (n-alkanes), whereas biomarkers of algae (steranes) were not detected. This suggests that, differently from modern Caribbean shelfs, this fine carbonate did not originate from the disgregation of green algae. A Pristane to Phytane ratio < 1 also suggests deposition under anoxic conditions, in agreement with the known status of "superanoxia" of earliest Triassic oceans. Overall, our observations suggest an aragonitic mineralogy of the carbonate mud, followed by calcite replacement and cementation in the marine burial early diagenetic environment. Our data strongly suggest that the early Triassic carbonate mud of the Dolomites was precipitated in the water column, similarly to the modern whitings of the Bahamas, and then settled on a shelf bottom below wave base. Our study shows that these lime-mudstones contain aragonite replaced by calcite and calcite cement, in variable proportions. The δ13C of

  5. Kinetics of Leaching Calcium from Dolomite

    Directory of Open Access Journals (Sweden)

    Azizi, A.

    2011-06-01

    Full Text Available Magnesia is obtained from magnesite ore and the production process applied should remove accompanying minerals that reduce its refractoriness. Given that magnesite reservoirs are more exploited and largely exhausted, there is a growing need for production of magnesia on the basis of other magnesium minerals. Dolomite is a promising source of magnesia because it forms large deposits, is easy to exploit, and generally contains a small quantity of impurities.The kinetics of calcium leaching from dolomite by magnesium-nitrate solution has been studied. The research program included the influence of temperature, mass fraction of magnesium nitrate in solution, dolomite particle size and leaching time. Time dependence of calcium leaching is described by relevant kinetic equations. Rate coefficients, their temperature dependence and Arrhenius activation energy have been determined.

  6. Laboratory-scale simulations with hydrated lime and organic ...

    African Journals Online (AJOL)

    cells (used to draw the dose response graphs). All chlorine exposure ... stock solutions and dosage ranges were prepared to perform jar stirring tests: ... Analytical laboratories analysing samples for SALCWTP have developed a more sensitive ...

  7. Lime pretreatment of lignocellulosic biomass

    Science.gov (United States)

    Chang, Shushien

    Lignocellulose is a valuable alternative energy source. The susceptibility of lignocellulosic biomass to enzymatic hydrolysis is constrained due to its structural features, so pretreatment is essential to enhance enzymatic digestibility. Of the chemicals used as pretreatment agents, it has been reported that alkalis improve biomass digestibility significantly. In comparison with other alkalis such as NaOH and ammonia, lime (calcium hydroxide) has many advantages; it is very inexpensive, is safe, and can be recovered by carbonating wash water. The effects of lime pretreatment were explored on switchgrass and poplar wood, representing herbaceous and woody biomass, respectively. The effects of pretreatment conditions (time, temperature, lime loading, water loading, particle size, and oxygen pressure) have been systematically studies. Lime alone enhances the digestibility of switchgrass significantly; under the recommended conditions, the 3-d total sugar (glucose + xylose) yields of lime-treated switchgrass were 7 times that of untreated sample. When treating poplar wood, lime must be combined with oxygen to achieve high digestibility; oxidative lime pretreatment increased the 3-d total sugar yield of poplar wood to 12 times that of untreated sample. In a fundamental study, to determine why lime pretreatment is effective, the effects of three structural features on enzymatic digestibility were studied: lignin content, acetyl content, and crystallinity index (CrI). Poplar wood was treated with peracetic acid, potassium hydroxide, and ball milling to produce model lignocelluloses with a broad spectrum of lignin contents, acetyl contents, and CrI, respectively. Enzymatic hydrolysis was performed on the model lignocelluloses to determine the digestibility. Correlations between lignin/carbohydrate ratio, acetyl/carbohydrate ratio, CrI and digestibility were developed. The 95% prediction intervals show that the correlations predict the 1-h and 3-d total sugar conversions of

  8. Arsenic removal by lime softening

    DEFF Research Database (Denmark)

    Kaosol, T.; Suksaroj, C.; Bregnhøj, Henrik

    2002-01-01

    This paper focuses on the study of arsenic removal for drinking water by lime softening. The initial arsenic (V) concentration was 500 and 1,000 ug/L in synthetic groundwater. The experiments were performed as batch tests with varying lime dosages and mixing time. For the synthetic groundwater......, arsenic (V) removal increased with increasing lime dosage and mixing time, as well as with the resulting pH. The residual arsenic (V) in all cases was lower than the WHO guideline of 10 ug/L at pH higher than 11.5. Kinetic of arsenic (V) removal can be described by a first-order equation as C1 = C0*e......^-k*t. The relation between the constant (k value) and increasing lime dosage was found to be linear, described by k = 0.0034 (Dlime). The results support a theory from the literature that the arsenic (V) was removed by precipitation af Ca3(AsO4)2. The results obtained in the present study suggest that lime...

  9. INFLUENCES OF LIMING ON YIELDS OF ALFALFA HAY

    Directory of Open Access Journals (Sweden)

    Svetislav Popović

    2009-06-01

    Full Text Available Alfalfa is the most important forage legume on cultivated fields in Croatia (about 45000 ha of growing area – status 2003. The field experiment with application of four dolomite (Agrovapno MgO: 56% CaO and 40% MgO rates (0, 10, 20, 30 and 40 tha-1 were conducted in autumn of 2004. The experiment was conducted by randomized block design in four replicates. Alfalfa (cultivar Osječanka 88 of the Agricultural Institute Osijek, Croatia was sown on March 25, 2005. Four cuttings / year were made. Fresh mass of alfalfa (cutting area 0.25 m2 was oven-dried at 65 oC. Year was the most influencing factor of alfalfa hay yields (13.03, 28.63, 29.43 and 32.77 tha-1, for 2005, 2006, 2007 and 2008, respectively. Liming resulted in low increases of yields up to 5% only. We presume that possible high tolerance of Osječanka 88 cultivar to soil acidity could be the main reason of low effects of liming on alfalfa yields.

  10. Nutritional characteristics of two pigeon pea hybrids – Liming and phosphated fertilization

    Directory of Open Access Journals (Sweden)

    Marcia Atauri Cardelli de Lucena

    2012-12-01

    Full Text Available The use of legumes in animal production systems can be a sustainable alternative as a protein source in rotational grazing system and/or as a protein bank. Pigeon pea (Cajanus cajan (L. Millsp. figure as an example of success of this use on animal nutrition. The development of this species can be limited by the high acidity and low soil phosphorus content. There is a lack of scientific information on the effects of liming and phosphorus fertilization on some nutritional variables of two pigeon pea new hybrids. This study was conducted in pots containing 5 kg of soil in a greenhouse at the Instituto de Zootecnia, Nova Odessa, São Paulo State. There were studied two pigeon pea hybrids, H1 and H2, and the treatments involved agronomic practices: 1 No liming and without phosphorus (control, 2 Liming (L, 3 Phosphorus fertilization (P and 4 Liming plus phosphorus. Liming was proposed to increase soil base saturation to 50%, it was used dolomite lime PRNT = 90%, in an amount corresponding to 4.5 t/ha. Phosphorus fertilization (as superphosphate rate was 60 kg/ha of PO25. The experimental units were allocated according to a complete randomised block design, with five replications. We analyzed the levels of crude protein (CP, neutral detergent fiber (NDF, acid detergent fiber (ADF, in pigeon pea shoot at 45 days of age. Statistical analyzes were performed using the software SISVAR, averages were compared using test for multiple comparisons Student Newman-Keuls - SNK test (P < 0.05. The H1 hybrid had the highest content of CP, by applying P, lime plus P and the control treatment compared to H2 hybrid. The association lime plus P resulted in higher content of CP mainly due to the increased availability of P for plants. Smaller values were observed for NDF in H2 with P application. Lower values of ADF were observed in H1 in both control treatment and P application. The ADF values were lower for the hybrid H2 only for the treatment lime plus P. The two

  11. Wood ash or dolomite treatment of catchment areas - effects of mercury in runoff water

    Energy Technology Data Exchange (ETDEWEB)

    Parkman, H.; Munthe, J. [Swedish Environmental Research Inst., Stockholm (Sweden)

    1996-11-01

    A future increased use of biomass as a source of energy, and the planned restoration of mineral nutrient balance in the forest soils by returning the wood ashes, has led to concern for new environmental disturbances. The objectives of the present study were to investigate if the outflow of total mercury (TotHg) and methyl mercury (MeHg) from catchment areas treated with granulated wood ash (1988, 2.2 tons/ha, `ashed area`) or dolomite (1985, 5 tons/ha, `limed area`) differed from the outflow from an untreated (reference) area, and if variations in Hg outflow were correlated with changes in the outflow of organic substances or pH. The study areas are situated in Vaermland, Sweden. Samples of run-off water were taken weekly or monthly (depending on water-flow) during on year (1993-94). The outflow of MeHg, TotHg as well as H+ and dissolved organic material (DOC) was lower from the limed area compared to the other two areas, which did not differ significantly. There was a strong covariation between concentrations of DOC and MeHg and a weaker relation between DOC and TotHg in the run-off waters. MeHg also covaried with temperature while TotHg covaried with pH and water-supply. No difference was found when comparing Hg-data from the limed area before, directly after and eight years after the liming event. 13 refs, 12 figs, 1 tab

  12. Freeze concentration of lime juice

    Directory of Open Access Journals (Sweden)

    Ampawan Tansakul

    2008-11-01

    Full Text Available The main objective of this research was to study the effects of processing conditions, i.e. cooling medium temperature (-6, -12 and -18C and scraper blade rotational speed (50, 100 and 150 rpm on the freeze concentration of lime juice. The initial soluble solid content of lime juice was 7.6 Brix. Results showed that soluble solid content of lime juice increased as cooling medium temperature decreased while scraper blade rotational speed increased. It was also found that the processing condition with -18˚C cooling medium temperature and 150 rpm rotational speed of the scraper blade was the best among all studied conditions, although the loss of the soluble solids with ice crystals during ice separation was relatively high at 35%.

  13. Mineral resource of the month: lime

    Science.gov (United States)

    ,

    2009-01-01

    The article presents facts about lime, which is said to be a caustic chemical manufactured from limestone or other calcium carbonates in a kiln at temperatures ranging from 935 to 1,350 degrees Celsius. It states that lime is widely used in industries such as steelmaking, paper production and chemical manufacturing. It also mentions that global lime production amounts up to 280 million metric tons annually. However, it notes that international trade in lime is limited.

  14. Characterization of Historica Lime Mortar from the Spanish Colonial Period in the Philippines

    Directory of Open Access Journals (Sweden)

    Jan-Michael C. Cayme

    2017-07-01

    Full Text Available Detailed scientific research applied to the field of cultural heritage is rarely practiced in the Philippines. This study intends to present a systematic approach to the proper chemical characterization of an old lime mortar sample from a Spanish-era church ruin. The analytical techniques employed were: atomic absorption spectroscopy (AAS, infrared spectroscopy (IR, scanning electron microscopy and energy-dispersive x-ray spectroscopy (SEM-EDX, and thermogravimetric analysis (TGA. Results showed that the binder is mostly calcitic, non-dolomitic and air-hardening lime. A slight hydraulic character was observed due to possible clay impurities. Besides the typical sand mixture in mortars, crushed shell fragments were used as aggregates. Possible organic compounds were also identified. The data obtained from this study is very important in understanding traditional building techniques that can enhance heritage conservation work in the Philippines.

  15. Geothermal convection: a mechanism for dolomitization at Enewetak Atoll?

    Science.gov (United States)

    Wilson, A.M.; Sanford, W.; Whitaker, F.; Smart, P.

    2000-01-01

    Geothermal convection in carbonate platforms could drive massive dolomitization by supplying mass transport of magnesium over long periods and at temperatures high enough to overcome kinetic limitations. Reactive-transport simulations based on Enewetak Atoll show dolomitization in a thin band at a permeability contrast near the base of the platform, which is consistent with field observations of dolomitized Eocene deposits. Dolomitization is predicted at approximately 6% per My at temperatures of 45–60°C, and complete dolomitization could be accomplished in ∼16 My. Calcium enrichment of pore fluids and upward transport of these fluids is established early, prior to 30 ky.

  16. Solid state sintering of lime in presence of La2O3 and CeO2

    Indian Academy of Sciences (India)

    T K Bhattacharya; A Ghosh; H S Tripathi; S K Das

    2003-12-01

    The sintering of lime by double calcination process from natural limestone has been conducted with La2O3 and CeO2 additive up to 4 wt.% in the temperature range 1500–1650°C. The results show that the additives enhanced the densification and hydration resistance of sintered lime. Densification is achieved up to 98.5% of the theoretical value with La2O3 and CeO2 addition in lime. Grain growth is substantial when additives are incorporated in lime. The grain size of sintered CaO (1600°C) with 4 wt.% La2O3 addition is 82 m and that for CeO2 addition is 50 m. The grains of sintered CaO in presence of additive are angular with pores distributed throughout the matrix. EDX analysis shows that the solid solubility of La2O3 and CeO2 in CaO grain is 2.9 and 1.7 weight %, respectively. The cell dimension of CaO lattice is 4.803 Å. This value decreases with incorporation of La2O3 and CeO2. The better hydration resistance of La2O3 added sintered lime compared to that of CeO2 added one, is related to the bigger grain size of the lime in former case.

  17. Terrestrial liming benefits birds in an acidified forest in the northeast.

    Science.gov (United States)

    Pabian, Sarah E; Brittingham, Margaret C

    2007-12-01

    Studies in Europe have reported negative effects of acid deposition on forest birds, and research in North America has identified links between forest bird abundance and rates of acid deposition. We examined the bird community in an acidified forest in central Pennsylvania (USA) and evaluated the effects of terrestrial lime application on birds. We used a before-after control-impact (BACI) study design, with one year of observation before (2003) and three years after lime application (2004, 2005, and 2006). Between the 2003 and 2004 field seasons, 4500 kg/ha of dolomitic lime were applied to two of four 100-ha watersheds. Each year, we monitored bird abundance and Ovenbird (Seiurus aurocapilla) eggshell thickness and territory size. Soil and snail abundance data were also collected. The bird community and territory size results indicated that the study area may be providing low-quality habitat for forest birds, perhaps as a result of acid deposition. We found lower forest bird abundances than have been found in less acidified areas of Pennsylvania, and larger Ovenbird territory sizes than have been found in other studies. We found a significant positive relationship between soil calcium and bird abundance, indicating that soil calcium may affect bird abundance. Liming increased soil calcium and pH and led to increased snail and bird abundances. After liming, bird abundance was positively related to snail abundance. No significant changes occurred in Ovenbird territory size or eggshell thickness. Our results suggest that acid deposition could be responsible for reduced bird abundance, and that liming is a potential mitigation technique.

  18. The influence of inner hydrophobisation on water transport properties of modified lime plasters

    Science.gov (United States)

    Pavlíková, Milena; Pavlík, Zbyšek; Pernicová, Radka; Černý, Robert

    2016-06-01

    The effect of hydrophobic agent admixture on water vapour and liquid water transport properties of newly designed lime plasters is analysed in the paper. The major part of physico - chemical building deterioration is related to the penetration of moisture and soluble salts into the building structure. For that reason, the modified lime plasters were in the broad range of basic material properties tested. From the quantitative point of view, the measured results clearly demonstrate the big differences in the behaviour of studied materials depending on applied modifying admixtures. From the practical point of view, plaster made of lime hydrate, metakaolin, zinc stearate and air-entraining agent can be recommended for renovation purposes. The accessed material parameters will be used as input data for computational modelling of moisture transport in this type of porous building materials and will be stored in material database.

  19. Gas hydrates

    Digital Repository Service at National Institute of Oceanography (India)

    Ramprasad, T.

    and the role it plays in the global climate and the future of fuels. Russia, Japan, Nigeria, Peru, Chile, Pakistan, Indonesia, Korea, etc are various countries who are perusing the gas hydrates studies as a future resource for fuel. Indian Initiative..., 1993, Free gas at the base of the gas hydrate zone in the vicinity of the Chile Triple junction: Geology, v. 21, pp. 905-908. Borowski, W.S., C.K. Paull, and U. William, III, 1999, Global and local variations of interstitial sulfate gradients...

  20. Lime application for the efficient production of nutraceutical glucooligosaccharides from Leuconostoc mesenteroides NRRL B-742 (ATCC13146).

    Science.gov (United States)

    Moon, Young Hwan; Madsen, Lee; Chung, Chang-Ho; Kim, Doman; Day, Donal F

    2015-02-01

    We have previously demonstrated the production of glucooligosaccharides via a fermentation of sucrose with Leuconostoc mesenteroides NRRL B-742 using sodium hydroxide (NaOH) to control the pH. Because NaOH is expensive, we sought to minimize the cost of our process by substituting hydrated lime and saccharate of lime (lime sucrate) in its place. The yield of glucooligosaccharides using either 5 % lime (41.4 ± 0.5 g/100 g) or 5 % lime sucrate (40.0 ± 1.4 g/100 g) were both similar to the NaOH control (42.4 ± 1.5 g/100 g). Based on this, it appears that the cost associated with pH control in our process can be reduced by a factor of approximately 2.4 using lime instead of NaOH. Because our chromatographic stage is based on a Ca(2+)-form resin to separate glucooligosaccharides, the use of lime not only negates the need for costly de-salting via ion-exchange (elimination of two ion-exchange sections) prior to separation, but also greatly reduces the resin regeneration cost.

  1. Changes in soil physical properties of a coal mining site influenced by liming, poultry manure and revegetation

    Energy Technology Data Exchange (ETDEWEB)

    Neto, A.L.; Albuquerque, J.A.; de Almeida, J.A.; Mafra, A.L.; Medeiros, J.C.; Alberton, A. [UDESC, Lages (Brazil)

    2008-07-15

    The physical, chemical and biological properties of soils of reconstructed areas after coal mining are altered. This study aimed to evaluate liming, mineral and organic fertilizers and revegetation effects on the physical properties of a reconstructed soil after open-pit mining. The experiment was carried out in a former mine in Lauro Muller County - SC, in southern Brazil, from 2001 to 2005. The site was mined in 1991 and reconstructed in 1995. A randomized complete block design was used, with three replications. The treatments consisted of. (1) Control; (2) 'dregs' (alkaline residue); (3) Lime; (4) Lime + Brachiaria brizantha; (5) Lime + Brachiaria brizantha + poultry litter. Pinus taeda and Eucalyptus saligna seedlings were transplanted to subplots of all treatments. Dolomitic limestone and dregs were incorporated in the soil at a depth of 10 cm. Nitrogen, potassium and phosphorous fertilizers were added on the soil surface of all plots according to the official recommendation. Soil samples were collected in February 2005 (from the layers 0-5 and 5-10 cm), and their physical and chemical properties evaluated. The treatments had no effects on soil bulk density, particle density, total porosity, macroporosity and microporosity. Liming increased pH, caused clay dispersion and reduced aggregates stability in water, while dregs increased pH without dispersing clay. Poultry litter and Brachiaria brizantha increased the aggregate stability and volumetric water content, thus favoring the recovery of soil physical quality in degraded areas.

  2. Clumped Isotopes in Bahamian Dolomites: A Rosetta Stone?

    Science.gov (United States)

    Murray, S.; Swart, P. K.; Arienzo, M. M.

    2014-12-01

    Low temperature dolomite formation continues to be an enigmatic process. However, with the advent of the clumped isotope technique, there is an opportunity to determine the temperature of formation as well as the δ18O of the fluid (δ18Ow) from which it formed. By using samples with a well constrained geologic and thermal history, we have attempted to accurately develop a technique for the application of clumped isotopes to varying dolomite systems. Samples for this study were taken from two cores, one from the island of San Salvador and one on Great Bahama Bank (known as Clino), located on the eastern and western edges respectively of the Bahamian Archipelago. Both cores penetrate through Pleistocene to Miocene aged carbonates. The San Salvador core has a 110m section of pure, near stoichiometric dolomite, while the Clino core is of a mixed carbonate composition with varying abundances (0% - 50%) of calcian dolomite (42-46 mol % MgCO3). The water temperature profile of the Bahamas can be assumed over time due to the stable geology and no influence of higher temperature waters. Because of its location and the present burial depth, the largest influence on dolomite formation has been changes in sea level. As the dolomites from San Salvador are 100% dolomite, the Δ47 was determined directly. The Clino dolomites however were only partially dolomitized and so were treated with buffered acetic acid to remove non-dolomite carbonates. This was carried out in stages, using X-ray diffraction to determine composition, followed by the measurement of Δ47 after each leaching episode. Because the dolomite formation temperature and δ18Ow can be constrained, it becomes possible to evaluate the applicability of the multitude of clumped isotope correction schemes that have been applied to various dolomite samples. Also tested were several different equations which link temperature to the δ18O of the dolomite allowing the δ18O of the water to be calculated. This is a necessary

  3. Evidence for carbon sequestration by agricultural liming

    Science.gov (United States)

    Hamilton, Stephen K.; Kurzman, Amanda L.; Arango, Clay; Jin, Lixin; Robertson, G. Philip

    2007-06-01

    Agricultural lime can be a source or a sink for CO2, depending on whether reaction occurs with strong acids or carbonic acid. Here we examine the impact of liming on global warming potential by comparing the sum of Ca2+ and Mg2+ to carbonate alkalinity in soil solutions beneath unmanaged vegetation versus limed row crops, and of streams and rivers in agricultural versus forested watersheds, mainly in southern Michigan. Soil solutions sampled by tension indicated that lime can act as either a source or a sink for CO2. However, infiltrating waters tended to indicate net CO2 uptake, as did tile drainage waters and streams draining agricultural watersheds. As nitrate concentrations increased in infiltrating waters, lime switched from a net CO2 sink to a source, implying nitrification as a major acidifying process. Dissolution of lime may sequester CO2 equal to roughly 25-50% of its C content, in contrast to the prevailing assumption that all of the carbon in lime becomes CO2. The ˜30 Tg/yr of agricultural lime applied in the United States could thus sequester up to 1.9 Tg C/yr, about 15% of the annual change in the U.S. CO2 emissions (12 Tg C/yr for 2002-2003). The implications of liming for atmospheric CO2 stabilization should be considered in strategies to mitigate global climate change.

  4. Investigation of the role of polysaccharide in the dolomite growth at low temperature by using atomistic simulations

    CERN Document Server

    Shen, Zhizhang; Szlufarska, Izabela; Xu, Huifang

    2016-01-01

    Dehydration of water from surface Mg2+ is most likely the rate-limiting step in the dolomite growth at low temperature. Here, we investigate the role of polysaccharide in this step using classical molecular dynamics (MD) calculations. Free energy (potential of mean force, PMF) calculations have been performed for water molecules leaving the first two hydration layers above the dolomite (104) surface under the following three conditions: without catalyst, with monosaccharide (mannose) and with oligosaccharide (three units of mannose). MD simulations reveal that there is no obvious effect of monosaccharide in lowering the dehydration barrier for surface Mg2+. However, we found that there are metastable configurations of oligosaccharide, which can decrease the dehydration barrier of surface Mg2+ by about 0.7-1.1 kcal/mol. In these configurations, the molecule lies relatively flat on the surface and forms a bridge shape. The hydrophobic space near the surface created by the non-polar -CH groups of the oligosaccha...

  5. Dolomite in caves: Recent dolomite formation in oxic, non-sulfate environments. Castañar Cave, Spain

    OpenAIRE

    Alonso-Zarza, Ana María; Martín Pérez, Andrea

    2008-01-01

    Dolomite is a common mineral in the rock record but rare in recent superficial environments. Where it does occur, it is related to anoxic, sulfate-rich environments and microbial activity. The occurrence of some dolomite deposits in caves, however, indicates that dolomite formation is also possible in oxic, non-sulfate settings. Dolomite is forming at 17 °C and in oxic-vadose conditions on the host rocks and aragonite speleothems of the Castañar Cave, Cáceres, Spain. It appears as...

  6. Petrologic and geochemical constraints on the origin of subsurface dolomite, Enewetak Atoll: An example of dolomitization by normal seawater

    Science.gov (United States)

    Saller, Arthur H.

    1984-04-01

    Dolomite is present 1,250 1,400 m below sea level in Eocene strata of Enewetak Atoll. Petrographically, the deep Enewetak dolomite postdates brittle compaction of rigid grains in the host Eocene strata. The 87Sr/86Sr ratio of these dolomites (0.70865 0.70901) indicates that they formed at one or more times between the middle Miocene and the present. Since the top of the lower Miocene is more than 900 m above the deep dolomitic interval, the dolomite must have formed at a minimum burial depth of 900 m. Stable-oxygen-isotope determinations suggest dolomite precipitation from cold marine water. Lower Miocene and Eocene carbonate strata on the atoll are apparently in open communication with cold, modern ocean water, suggesting that those same strata were in open communication with ocean water during dolomitization. At a depth of about 1,000 m, modern Pacific Ocean water becomes undersaturated with respect to calcite but is still supersaturated with respect to dolomite. Therefore, it is proposed that the deep Enewetak dolomite precipitated from cold, deep ocean water (undersaturated with respect to calcite) at a burial depth of more than 900 m.

  7. PCM-enhanced lime plasters for vernacular and contemporary architecture

    Science.gov (United States)

    Theodoridou, Magdalini; Kyriakou, Loucas; Ioannou, Ioannis

    2016-04-01

    In 1997, the European Union (EU) pledged to reduce the amount of greenhouse gas emissions by 20% below the levels of 1990 by the end of 2020. In recent years it has become evident that, in order to reach that goal, EU Member States must take measures to encourage sustainability in the building industry, which is a major energy consumer. Such measures should involve the use of innovative, environmentally friendly materials and methods in new constructions, as well as the renovation of existing properties by upgrading their current state of energy efficiency. Phase Change Materials (PCMs) have the ability to absorb and release thermal energy, in the form of latent heat, during the melting or solidifying processes respectively. Thus, they may be used as additives in the production of thermally efficient composite building materials. A PCM-enhanced plaster is a heat storage medium combining an appropriate PCM with a cementitious or non-cementitious matrix to produce a low-cost thermal storage material with structural and thermostatic properties. Although innovative technologies, such as PCMs, have certainly contributed to the boost in the evolution of the building materials industry in recent years, a significant proportion of these technologies and practices have not yet been fully exploited in materials based on traditional principles. This paper focuses on the design and production of novel cementless PCM-enhanced lime plasters, in line with the traditional production technology of lime composites. The new plasters are produced using either hydrated or natural hydraulic lime binder, crushed calcarenite sand (0-2 mm) and commercial microencapsulated PCM in powder form (5% w/w of solids). Results from comparative tests between reference mixtures and mixtures with the addition of PCM, carried out 28, 56 and 90 days after laboratory production, prove the potential of PCMs in enhancing the thermal performance of traditional lime-based composites. The modified composites

  8. Constraining dolomitization by Mg isotopes: A case study from partially dolomitized limestones of the middle Cambrian Xuzhuang Formation, North China

    Science.gov (United States)

    Peng, Yang; Shen, Bing; Lang, Xian-Guo; Huang, Kang-Jun; Chen, Ji-Tao; Yan, Zhen; Tang, Wen-bo; Ke, Shan; Ma, Hao-Ran; Li, Fang-Bing

    2016-03-01

    The "dolomite problem" refers to the rare dolomite formation in modern oceans that is in sharp contrast to the widespread ancient dolostone in rock record, as well as failure of laboratory inorganic dolomite precipitation at near Earth-surface temperature. Novel Mg isotope systematics provides a promising tool in resolving the "dolomite problem". Here, we develop a protocol to place constraints on the dolomitization process by using Mg isotopes. In this study, we measured Mg isotopic compositions (δ26Mg) of two batches of partially dolomitized limestone samples from the middle Cambrian Xuzhuang Formation in North China. δ26Mg varies between -0.55‰ and -3.18‰, and shows a negative linear correlation with 1>/[Mg>], suggesting that δ26Mg can be described by a binary mixing between the calcite and dolomite components. Mg isotopic composition of the dolomite component (δ26Mgdol) for the lower sample set that is collected from a 4 m stratigraphic interval containing three high-frequency ribbon rock-packstone cycles is -1.6‰, while δ26Mgdol for the upper sample set (from a thick sequence of ribbon rock) is significantly higher (-0.3‰). However, neither mineralogical and elemental compositions, carbon and oxygen isotopes, nor crystal morphologies of dolomite provides diagnostic criteria to differentiate these two batches of samples. δ26Mgdol of the Xuzhuang limestone is simulated by the Advective Flow (AF) and the Diffusion-Advection-Reaction (DAR) models. The AF model assumes that Mg is transported by advective fluid flows, while the DAR model simulates a contemporaneous seawater dolomitization process, in which Mg is delivered by diffusion. The AF modeling result indicates that δ26Mg of the dolomitization fluid is +0.4‰ and +1.7‰ for the lower and upper sample sets, respectively. These values are significantly higher than modern and Cenozoic seawater Mg isotopic composition, suggesting that the dolomitization fluid is not contemporaneous seawater. The

  9. Corrosion effects on soda lime glass

    NARCIS (Netherlands)

    Veer, F.A.; Rodichev, Y.M.

    2010-01-01

    Although soda lime glass is the most common used transparent material in architecture, little is known about the corrosion effects on long term strength and the interaction between corrosion and defects. Extensive testing on soda lime bars under different environmental conditions and different degre

  10. Simple Analysis of Historical Lime Mortars

    Science.gov (United States)

    Pires, Joa~o

    2015-01-01

    A laboratory experiment is described in which a simple characterization of a historical lime mortar is made by the determination of its approximate composition by a gravimetric method. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) are also used for the qualitative characterization of the lime mortar components. These…

  11. Simple Analysis of Historical Lime Mortars

    Science.gov (United States)

    Pires, Joa~o

    2015-01-01

    A laboratory experiment is described in which a simple characterization of a historical lime mortar is made by the determination of its approximate composition by a gravimetric method. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) are also used for the qualitative characterization of the lime mortar components. These…

  12. Corrosion effects on soda lime glass

    NARCIS (Netherlands)

    Veer, F.A.; Rodichev, Y.M.

    2010-01-01

    Although soda lime glass is the most common used transparent material in architecture, little is known about the corrosion effects on long term strength and the interaction between corrosion and defects. Extensive testing on soda lime bars under different environmental conditions and different

  13. Review of Dolomite as Precursor of Geopolymer Materials

    Directory of Open Access Journals (Sweden)

    Azimi E.A.

    2016-01-01

    Full Text Available Geopolymer is an environmentally friendly cementitious binder that does not require the existence of ordinary Portland cement (OPC. Geopolymer has many excellent advantages, including high early strength, low shrinkage, good thermal resistance and good chemical resistance. Previous commonly used materials include fly ash, clay and slag. The used of dolomite as precursor material in geopolymer field is still new and at the early stage of study. Only a few researchers have done studies on dolomite in geopolymer. Dolomite (CaMg(CO32 is abundant and generally inexpensive natural minerals. The possible use of these bulk calcium carbonate materials in improving the mechanical properties of geopolymers will therefore be of great interest. This paper summarizes some research outcomes on dolomite in geopolymer along with the potential of dolomite as geopolymer composites.

  14. LANDSCAPE ARCHAEOLOGY ALONG LIMES TRANSALUTANUS

    Directory of Open Access Journals (Sweden)

    Eugen S. Teodor

    2014-09-01

    Full Text Available The project addresses the historical monuments comprised in the longest Roman ‘linear defence’ structure present on the Romanian territory.Despite it being the longest, this historic structure is the least protected and the least known in its technical details. Was indeed Limes Transalutanus an incomplete limes (lacking civilian settlements, for example, an odd construction (a vallum without fossa, an early-alarm line rather than a proper defensive line? Taking on these historical and archaeological challenges, the team attempts to develop an investigation technology applicable to large scale archaeological landscapes - a full evaluation chain, involving aerial survey, surface survey, geophysical investigation, multispectral images analysis, statistic evaluation and archaeological diggings. This technological chain will be systematically applied on the whole length of the objective, that is, on a 155 km distance. The attempt to find answers to issues related to the earth works’ functionality, layout, structure, chronology and relation with adjacent sites will be grounded on exploring the relations of the monument with the surrounding environment, by focussing on finding methods to reconstruct the features of the ancient landscapes, like systematic drilling, palynological tests and toponymical studies.

  15. Evaluation of Lime for Use in Mortar

    Directory of Open Access Journals (Sweden)

    Naktode P.L.

    2014-02-01

    Full Text Available Lime has been used in India as material of construction from very ancient days. The manner in which lime structures about 2000 years old have withstood the ravages of time bear irrefutable evidence to the durability of lime mortars. Lime mortars were the mortars of very recent years – used until the twentieth century. Although they are almost forgotten today, they still remain a viable and important construction method [1]. There is something about this material that remains just as valuable today as it was 150 years ago [2]. The lime belt of Vidarbha area is not of industrial grade. To use for construction purpose it needs some improvement and alteration in the ingredients. This calls the development of an alternative approach to make it suitable for construction in large extent. Keywords:

  16. Study of dolomite dissolution at various temperatures - Evidence for the formation of nanocrystalline secondary phases at dolomite surface and influence on dolomite interactions with other minerals

    Science.gov (United States)

    Debure, M.; Andreazza, P.; Grangeon, S.; Lerouge, C.; Montes-Hernandez, G.; MADE, B.; Tournassat, C.

    2015-12-01

    In most clay-rock geological formation studied for the storage of nuclear waste, pore water compositions are expected to be at equilibrium with carbonate minerals, which are always included in predictive models for pore water composition calculations [1]. Among the carbonates known to be present, dolomite may be problematic in the pore water composition calculation because its solubility spans a large range of values as a function of its crystallinity in thermodynamic databases. In addition, the composition of dolomite minerals observed in clay-rock formations such as Callovian-Oxfordian or Opalinus clay formation differs from this of a pure dolomite: the Ca/Mg stoichiometry is not ideal, and the minerals contain minor amounts of Fe and traces of many other elements [2]. To understand the influence of secondary phases precipitation during dolomite dissolution on pore water chemistry, the dissolution of monocrystals of dolomite were investigated at 25 °C and at 80 °C in a pH range 3 to 8 for various time periods (30 minutes to 21 days) in sealed PTFE reactors. Solution analyses evidenced a stoichiometric release of Ca and Mg in solution during dolomite dissolution. Scanning Electron Microscopy (SEM), Raman and X-Ray Diffraction (XRD) analyses did not evidence secondary Mg-bearing minerals precipitation, but revealed the formation of Fe-bearing particles on the dolomite surface. Morphological characterizations performed with Small-angle X-ray scattering (SAXS) evidenced that the precipitation occurs along a specific crystallographic plane of the dolomite monocrystal. Thus, the precipitated nanoparticles clustered on specific surface sites, and are made of Fe-rich phases poorly crystallized (carbonates, oxides and hydroxides). [1] Tournassat et al. 2015. Ch. 3: Chemical Conditions in Clay-Rocks. Natural and Engineered Clay Barriers, Elsevier. [2] Lerouge et al. 2011. Geochim. et Cosmoch. Acta, 2011, 75, 2633-2663.

  17. Biomineralization of dolomite and magnesite discovered in tropical coralline algae: a biological solution to the geological dolomite problem

    Science.gov (United States)

    Nash, M. C.; Troitzsch, U.; Opdyke, B. N.; Trafford, J. M.; Russell, B. D.; Kline, D. I.

    2011-06-01

    Dolomite is a magnesium-rich carbonate mineral abundant in fossil carbonate reef platforms but surprisingly rare in modern sedimentary environments, a conundrum known as the ''Dolomite Problem". Marine sedimentary dolomite has been interpreted to form by an unconfirmed, post-depositional diagenetic process, despite minimal experimental success at replicating this. Here we show that dolomite, accompanied by magnesite, forms within living crustose coralline alga, Hydrolithon onkodes, a prolific global tropical reef species. Chemical micro-analysis of the coralline skeleton reveals that not only are the cell walls calcitised, but that cell spaces are typically filled with magnesite, rimmed by dolomite, or both. Mineralogy was confirmed by X-ray diffraction. Thus there are at least three mineral phases present (magnesium calcite, dolomite and magnesite) rather than one or two (magnesium calcite and brucite) as previously thought. Our results are consistent with dolomite occurrences in coralline algae rich environments in fossil reefs. Instead of a theory of post-depositional dolomitisation, we present evidence revealing biomineralization that can account for the massive formations seen in the geologic record. Additionally, our findings imply that previously unrecognized dolomite and magnesite have formed throughout the Holocene. This discovery together with the scale of coralline algae dominance in past shallow carbonate environments raises the possibility that environmental factors driving this biological dolomitisation process have influenced the global marine magnesium/calcium cycle. Perhaps, most importantly, we reveal that what has been considered a geological process can be a biological process, having many implications for both disciplines.

  18. The effects of limestone type on the sulphur capture of slaked lime

    Energy Technology Data Exchange (ETDEWEB)

    Z.O. Siagi; M. Mbarawa; A.R. Mohamed; K.T. Lee; I. Dahlan [Tshwane University of Technology, Pretoria (South Africa). Department of Mechanical Engineering

    2007-12-15

    This study examines the effect of the chemical composition and origin on the performance of two calcitic and two dolomitic limestones from different sources in South Africa. The experiments were carried out in a fixed bed reactor maintained at 80{sup o}C. The raw sorbent materials were calcined at 900{sup o}C and the resulting quicklime hydrated to produce the relevant hydrates which were used in the tests. Results obtained show that the maximum temperature rise during the hydration of the samples varied from 5 to 65{sup o}C depending on the chemical composition of the sorbent. Sorbents with higher temperature rise resulted in products with a more porous structure and a better performance in the sulphur capture. The maximum sorbent conversion in terms of mol of SO{sub 2} per mol of sorbent varied from 0.0274 for dolomitic limestones to 0.1823 for the calcitic limestones. The presence of Fe{sub 2}O{sub 3} in small quantities was observed to have a positive effect on the performance of the sorbent. 21 refs., 4 figs., 3 tabs.

  19. Responses of Acer saccharum canopy trees and saplings to P, K and lime additions under high N deposition

    Energy Technology Data Exchange (ETDEWEB)

    Gradowski, T. [Alberta Univ., Edmonton, AB (Canada). Dept. of Renewable Resources; Thomas, S.C. [Toronto Univ., ON (Canada). Faculty of Forestry

    2008-02-15

    This study examined the physiological and morphological responses of Acer Saccharum canopy trees and 2-year old saplings to non-nitrogenous mineral nutrients. The study was conducted to test 4 hypotheses, notably, (1) that liming increased the availability of phosphate by decreasing soil acidity; (2) that Acer Saccharum showed increased physiological and growth performance in response to liming and phosphorus (P) and potassium (K); (3) that the physiological and growth effects of liming and P and K additions are more pronounced in sapling than in mature canopy trees; and (4) that canopy physiological and shoot extension responses precede radial growth responses in mature trees. Fifty-two mature Acer saccharum trees and 138 saplings were treated with 2 fertilizers and potassium chloride alone or in combination with dolomitic lime. Treatments were applied in a 2-level factorial randomized design to mature trees and to saplings. Mineral soil samples were then collected from depths of between 0 and 30 cm. Concentrations of carbon (C) and nitrogen (N) in mineral soil were determined using combustion analysis. Morphological chemical analyses were also conducted. Growth was examined at 5-year and 2-year intervals in order to examine nutrient addition effects on diameter increment. Data were used in a graphical vector nutrient analysis as well as in an analysis of variance (ANOVA). Results of the study showed that nutrients were adsorbed in the mineral soil and taken up by the trees within 1 year of fertilizer application. Liming had no effect on soil P availability. Both the saplings and the trees showed significant responses to both P and K fertilization and liming, including increased foliar nutrient concentration, leaf size and shoot extension growth. It was concluded that the vector analysis of shoot extension growth was consistent with sufficiency of N, but showed marked limitation of P and co-limitation by calcium (Ca) in saplings. 111 refs., 2 tabs., 5 figs.

  20. ORDERED INDEX AND DEDOLOMITIZATION OF DOLOMITE CRYSTALS%白云石晶体的有序度与去白云石化反应

    Institute of Scientific and Technical Information of China (English)

    邓敏; 唐明述; 钱光人

    2001-01-01

    评价了不同结构组分类别岩石中白云石晶体的有序度,并通过研究在悬浮分散体系中具有不同有序度的白云石晶体去白云石化反应的动力学行为,建立了白云石有序度与白云石去白云石化反应活性之间的关系。结果表明,泥晶白云岩中白云石晶体的有序度最低;白云质泥晶灰岩、泥质条带白云质泥晶灰岩、白云质粉屑砂屑泥晶灰岩及白云质亮晶鲕粒灰岩中的白云石晶体的有序度次之;豹斑白云质泥晶灰岩、粉晶以上晶粒白云岩中的白云石为近完全有序或完全有序。有序度低的白云石晶体去白云石化反应的扩散活化能、界面化学反应活化能和晶体成核与生长活化能也低,低有序度的白云石具有高的反应性。随着体系温度的升高,白云石晶体有序度对去白云石化反应的影响趋于减小,不同有序度白云石的去白云石化程度趋于相同。%The ordered index of dolomite crystals in dolomitic rocks with differe nt textures and compositions has been evaluated. The influence of the ordered in dex on dynamic of dedolomitization reaction were carried out by determining of r eaction degree of dolomite in suspended powdered dolomite-H2O system. It was est ablished that the ordered index of dolomite crystals is the smallest in dolomicr ites, moderate in dolomitic micrite limestones, stripped dolomitic micrite limes tones, dolomitic silt micrite limestones and dolomitic oosparites, and the large st in leopard dolomitic micrite limestones and crystalline dolostone. The dedolo mitization reaction of dolomite crystals with low ordered index occupies low act ive energy of diffusion, interfacial chemical reaction as well as nucleation and growth. Therefore, lowly ordered dolomite crystals show high reactivity in alka li solutions. Temperature tends to diminish the influence of ordered index on de dolomitization reaction of dolomite crystals.

  1. Lactic Acid Fermentation, Urea and Lime Addition: Promising Faecal Sludge Sanitizing Methods for Emergency Sanitation.

    Science.gov (United States)

    Anderson, Catherine; Malambo, Dennis Hanjalika; Perez, Maria Eliette Gonzalez; Nobela, Happiness Ngwanamoseka; de Pooter, Lobke; Spit, Jan; Hooijmans, Christine Maria; de Vossenberg, Jack van; Greya, Wilson; Thole, Bernard; van Lier, Jules B; Brdjanovic, Damir

    2015-10-29

    In this research, three faecal sludge sanitizing methods-lactic acid fermentation, urea treatment and lime treatment-were studied for application in emergency situations. These methods were investigated by undertaking small scale field trials with pit latrine sludge in Blantyre, Malawi. Hydrated lime was able to reduce the E. coli count in the sludge to below the detectable limit within 1 h applying a pH > 11 (using a dosage from 7% to 17% w/w, depending faecal sludge alkalinity), urea treatment required about 4 days using 2.5% wet weight urea addition, and lactic acid fermentation needed approximately 1 week after being dosed with 10% wet weight molasses (2 g (glucose/fructose)/kg) and 10% wet weight pre-culture (99.8% pasteurised whole milk and 0.02% fermented milk drink containing Lactobacillus casei Shirota). Based on Malawian prices, the cost of sanitizing 1 m³ of faecal sludge was estimated to be €32 for lactic acid fermentation, €20 for urea treatment and €12 for hydrated lime treatment.

  2. Pore structure and carbonation in blended lime-cement pastes

    Directory of Open Access Journals (Sweden)

    Álvarez, J. I.

    2006-06-01

    Full Text Available The present study aims to gain a fuller understandingof the curing process in lime pastes (100, 90, 80, 70,60, 50 and 40% lime blended with cement by analyzingcarbonation in these materials. A hydrated, airslaked lime powder and CEM II A/L 32.5 Portlandcement were used for the blends. These materialswere singled out for research primarily because theymay be used in the restoration of heritage monuments.Variation in weight was used as an indicator for carbonation.A new parameter, A, was found to vary inverselywith the percentage of the cement because of theprevalence of Knudsen diffusion in the paste, in turndue to the characteristics of the pore structure, whichwas studied by mercury intrusion porosimetry (MIP.The hygroscopic study conducted on the different pastesprovided information on water content at a givenhumidity and its location, i.e., adsorbed on the surfaceof the pores or condensed inside them, obstructing thediffusion of CO2. The conclusion drawn from this studyof the curing process was that neither drying nor C3Shydration retarded lime carbonation.En este trabajo se estudia el proceso de carbonatacionen pastas mixtas de cal y cemento (100, 90, 80, 70, 60,50 y 40% de cal con el objeto de obtener un mejorconocimiento del proceso de curado en estos materiales.Para ello se ha empleado una cal aerea hidratada en polvoy un cemento Portland del tipo CEM II A/L 32,5. Enparticular, este estudio investiga estos materiales ya quepueden ser utilizados en la restauracion del PatrimonioCultural. Se ha utilizado la variacion de peso como indicadordel proceso de carbonatacion. Se ha establecidoun nuevo parametro, A, que varia inversamente con elporcentaje de cemento en la pasta, debido al predominiode la difusion de Knudsen como consecuencia de laestructura porosa, que ha sido estudiada por medio deporosimetria de intrusion de mercurio (PIM. El estudiohigroscopico realizado sobre las diversas pastas permiteconocer el contenido en agua a una

  3. DOLOMITE AS AN ALTERNATIVE WEIGHTING AGENT IN DRILLING FLUIDS

    Directory of Open Access Journals (Sweden)

    M. J. BADRUL

    2007-08-01

    Full Text Available A series of experimental tests have been conducted to assess the suitability of using dolomite as an alternative weighting agent in drilling fluids. Currently, barite is widely used as weighting agent in drilling fluids slurry to ensure proper weights are achieved. However, barite contains toxic materials which make it unattractive from health and environment point of views. This is especially true when drilling operations are offshore, where most of the used drilling fluids will be dumped back into the sea. In this work, rheological properties of dolomite blend drilling fluids slurry were studied. Dolomite rocks were first crushed to produce dolomite powder, before being mixed with water and bentonite at various proportions. A total of 10 samples which contains various percentages of water, bentonite and dolomite were studied. For each sample, its rheological properties were determined. Such properties include density from mud balance, viscosity from viscometer, filtrate loss from API filter press and gel strength. The effect of aging on the properties of drilling fluids was also studied. From the study, it is concluded that Sample E, which consists of 70% dolomite by weight, produces the most stable drilling fluids. It is also observed that the amount of 336 g of dolomite in the sample shows the similar physical and rheological properties to that of the 480 g barite in the sample although the density for both samples is not same.

  4. The interaction of dolomite surfaces with metal impurities: a computer simulation study.

    Science.gov (United States)

    Austen, Kat F; Wright, Kate; Slater, Ben; Gale, Julian D

    2005-12-21

    This study investigates the behaviour of selected, morphologically important surfaces of dolomite (CaMg(CO3)2), using computational modelling techniques. Interatomic potential methods have been used to examine impurity substitution at cationic sites in these surfaces. Environmentally prevalent cations were studied to this end, namely Ni2+, Co2+, Zn2+, Fe2+, Mn2+ and Cd2+, all of which are also found as end-member carbonate minerals. Solid-solution substitution was investigated and showed that Cd and Mn will substitute from their end-member carbonate phase at either dolomite cation site. Mn is found to preferentially substitute at Mg sites, in agreement with experimental findings. For Ni2+, Co2+ and Zn2+, the magnitude of substitution energies is approximately equal for all surfaces, with the exception of the (1014) surface. However, for the larger cations, a far greater disparity in substitution energies is observed. At a stepped surface, analogous substitutions were performed and it was found that substitution energies for all impurity cations were reduced, indicating that uptake is more viable during growth. The predominant surface, the (1014), was solvated with a monolayer of water in order to investigate the influence of hydration on substitution energetics. The addition of water changes the relative preference for substitution of the different cations. Under aqueous conditions, the substitution energy is determined by three competing factors, the relative importance of which cannot be predicted without this type of computational investigation.

  5. The shrinkage in lime mortars

    Directory of Open Access Journals (Sweden)

    Sánchez, J. A.

    1997-03-01

    Full Text Available Nowadays, the methodology existing to measure the shrinkage in air, developed for paste and cement mortars, has serious problems to be applied to lime mortars, due to its different mechanism of hardening several modifications in Norms UNE 80-113-86 y 80-112-89 make possible the determination of the shrinkage in these traditional mortars.

    La metodología existente en la actualidad para la medida de la retracción de secado, desarrollada para las pastas y los morteros de cemento, presenta serios problemas a la hora de su aplicación a los morteros de cal debido a su distinto mecanismo de endurecimiento. Algunas modificaciones de las normas UNE 80-113-86 y 80-112-89 hacen posible la determinación de la retracción en estos morteros tradicionales.

  6. Nanotoxicity of dolomite mineral of commercial importance in India.

    Science.gov (United States)

    Patil, Govil; Khan, Mohd Imran; Akhtar, Mohd Javed; Ashquin, Mohd; Sultana, Sarwat; Ahmad, Iqbal

    2011-02-01

    The risk of occupational exposure to dolomite, an important mineral exists both in organized as well as unorganized sectors. Toxicological profiles of bulk dolomite are meagerly known in general and its nanotoxicity in particular. Effects of micro- and nano particles on cell viability, LDH leakage and markers of oxidative stress were observed. The study indicated that cytotoxicity of dolomite nanoparticles is significantly higher than the microparticles. The study thus suggests for the prescription of exposure limit for nanodolomite in the best interest of health of workers at risk of exposure under mining, milling and industrial environment.

  7. 煤粉炉渣/粉煤灰-石灰体系反应特性及差异%Reaction Characteristics and Difference of Cinder-Lime and Fly Ash-Lime System

    Institute of Scientific and Technical Information of China (English)

    陆金驰; 林少敏; 陈凯; 黄金林; 闫健

    2013-01-01

    通过测定原材料反应程度、试样水化产物、显微结构和抗压强度等方法研究了煤粉炉渣-石灰与粉煤灰-石灰体系在常温常压及蒸压条件下的反应过程,并结合FTIR、溶出性SiO2 、Al2O3等手段分析两种体系反应过程差异的机理,结果表明,煤粉炉渣-石灰体系在常温常压及蒸压条件下的反应程度均高于粉煤灰-石灰体系,生成的水化产物较多,水化产物钙硅物质的量比低,制品强度较高.煤粉炉渣-石灰体系反应程度更高的原因在于煤粉炉渣红外光谱1100 cm-1附近强吸收区的Si-O伸缩振动频率较低,Si-O结构更容易破坏,溶出参与反应的SiO2、Al203更多,试样的抗压强度越高.%From reaction degree,hydration product,microstructure and compressive strength,reaction process of cinder-lime system was studied under normal temperature and pressure curing and autoclaved curing by contrast with fly ash-lime system that is used widely in industry.FTIR and The mass fractions of active SiO2 and Al2O3 were used to research reaction mechanism.The result show that reaction ability of cinder-lime system is stronger than fly ash-lime system under normal temperature and pressure curing and autoclaved curing,cinder-lime system forms more hydration product and lower n (Ca)/n (Si) C-S-H,it has higher compressive strength.Higher reaction ability of cinder-lime system is due to cinder has lower Si-O stretching vibration wave number about 1100 cm-1 in strong absorption region of IR,more and faster dissolution of SiO2 and Al2O3 reacted with lime,thus cinder-lime system has higher compressive strength than fly ash-lime system under normal temperature and pressure curing and autoclaved curing.

  8. Volume Change Measurement Of Collapsible Soil Stabilized With Lime And Waste Lime

    Directory of Open Access Journals (Sweden)

    Khawla A. Al-Juari

    2013-05-01

    Full Text Available This paper presents a series of laboratory tests to evaluate the effects of lime and waste lime on the volume change and strength characteristics of moderately collapsible soil selected from Al-Rashidia in Mosul city. The tests are performed at different percentages of lime and waste lime of 0, 0.25, 0.5, 1.0, 2.0, 3.0, 4.0, 6.0 and 8.0% by dry weight of soil. One dimensional compression tests are conducted to clarify the influences of relative compaction, compaction water content, vertical stress level and curing time on the volume change and strength characteristics.The results of this study indicated a decrease in the plasticity, swelling potential and swelling pressure of treated soil. The soil became non-plastic at (3&6% of lime and waste lime respectively. Swelling pressure and swelling potential reached to zero at 2% lime and  2&7 days of curing time.Unconfined compressive strength (UCS reached to maximum value at optimum stabilizers content. The UCS of lime treated soil is more than that treated by waste lime at different curing time. The collapse index and potential of treated soil are found less than that of natural soil and decrease with increasing stabilizer content until drop to zero at 2% lime. Collapsing increased continuously with applied stresses, but with curing time reached a maximum value at 2 day. On the other hand, collapsing of treated soil with lime is less than that  of waste lime treated soil at different curing time and stresses.

  9. Clathrate hydrates in nature.

    Science.gov (United States)

    Hester, Keith C; Brewer, Peter G

    2009-01-01

    Scientific knowledge of natural clathrate hydrates has grown enormously over the past decade, with spectacular new findings of large exposures of complex hydrates on the sea floor, the development of new tools for examining the solid phase in situ, significant progress in modeling natural hydrate systems, and the discovery of exotic hydrates associated with sea floor venting of liquid CO2. Major unresolved questions remain about the role of hydrates in response to climate change today, and correlations between the hydrate reservoir of Earth and the stable isotopic evidence of massive hydrate dissociation in the geologic past. The examination of hydrates as a possible energy resource is proceeding apace for the subpermafrost accumulations in the Arctic, but serious questions remain about the viability of marine hydrates as an economic resource. New and energetic explorations by nations such as India and China are quickly uncovering large hydrate findings on their continental shelves.

  10. Characterization of a lime-pozzolan plaster containing phase change material

    Energy Technology Data Exchange (ETDEWEB)

    Pavlíková, Milena; Pavlík, Zbyšek; Trník, Anton; Pokorný, Jaroslav; Černý, Robert [Department of Materials Engineering and Chemistry, Faculty of Civil Engineering, Czech Technical University in Prague, Thákurova 7, 166 29 Prague (Czech Republic)

    2015-03-10

    A PCM (Phase Change Material) modified lime-pozzolan plaster for improvement of thermal energy storage of building envelopes is studied in the paper. The investigated plaster is composed of lime hydrate, pozzolan admixture based on metakaolin and mudstone, silica sand, water and paraffin wax encapsulated in polymer capsule. The reference plaster without PCM application is studied as well. The analyzed materials are characterized by bulk density, matrix density, total open porosity, compressive strength and pore size distribution. The temperature of phase change, heat of fusion and crystallization are studied using DSC (Difference Scanning Calorimetry) analysis performed in air atmosphere. In order to get information on materials hygrothermal performance, determination of thermal and hygric properties is done in laboratory conditions. Experimental data reveal a substantial improvement of heat storage capacity of PCM-modified plaster as compared to the reference material without PCM.

  11. Threats and opportunities for post-closure development in dolomitic ...

    African Journals Online (AJOL)

    Threats and opportunities for post-closure development in dolomitic ... in the form of sinkholes and widespread radioactive pollution exacerbate such fears. ... developments such as aquaculture, agriculture and different forms of tourism relating ...

  12. Effect of liming on nickel bioavailability and toxicity to oat and soybean grown in field soils containing aged emissions from a nickel refinery.

    Science.gov (United States)

    Cioccio, Stephen; Gopalapillai, Yamini; Dan, Tereza; Hale, Beverley

    2017-04-01

    Remediation of soils elevated in trace metals so that the soils may provide ecosystems services is typically achieved through pH adjustment or addition of sorbents. The present study aimed to generate higher-tier in situ toxicity data for elevated nickel (Ni) in soils with and without lime addition and to explore the effect of liming on soil chemistry and bioavailability of Ni to plants. A multiyear study of agronomic yield of field-grown oat and soybean occurred in 3 adjacent fields that had received air emissions from a Ni refinery for 66 yr. The soil Ni concentration in the plots ranged between 1300 mg/kg and 4900 mg/kg, and each field was amended with either 50 Mg/ha, 10 Mg/ha, or 0 Mg/ha (or tonnes/ha) of crushed dolomitic limestone. As expected, liming raised the pH of the soils and subsequently reduced the plant availability of Ni. Toxicity thresholds (effective concentrations causing 50% reduction in growth) for limed soils supported the hypothesis that liming reduces toxicity. Relationships were found between relative yield and soil cation exchange capacity and between relative yield and soil pH, corroborating findings of the European Union Risk Assessments and the Metals in Asia studies, respectively. Higher tier ecotoxicity data such as these are a valuable contribution to risk assessment for Ni in soils. Environ Toxicol Chem 2017;36:1110-1119. © 2016 SETAC. © 2016 SETAC.

  13. Rheology of cement mixtures with dolomite filler

    Directory of Open Access Journals (Sweden)

    Martínez de la Cuesta, P. J.

    2000-06-01

    Full Text Available This experimental program has studied the behavior of fresh paste made up from cements mixed with dolomite filler. Through prior experiments the starting point is obtained for the designs 22 and 23 factorials. With these designs the governing equations are established that influence the specific surface of the filler, the filler percentage and the ratio water/(cement + filler, used as objective functions: test probe penetration, flow on table and shear stress in viscometer. Also the type of rheological conduct is determined and the influence over initial and final setting is observed.

    Este programa experimental estudia el comportamiento de las pastas frescas fabricadas a partir de cementos mezclados con filler dolomítico. En los experimentos previos se obtiene el punto central para los diseños 22 y 23 factoriales. Con estos diseños se establecen las ecuaciones que rigen la influencia de la superficie específica del filler, el porcentaje de filler y la relación agua/(cemento + filler, utilizando como funciones objetivos la penetración de sonda, la mesa de sacudidas y la tensión de corte en el viscosímetro. También se determina el tipo de conducta reológica y la influencia sobre el principio y fin de fraguado.

  14. Lime-Crusted Rammed Earth: Materials Study

    OpenAIRE

    Mileto, Camilla; Vegas López-Manzanares, Fernando; Alejandre, Francisco Javier; Martín, Juan Jesús; Garcia Soriano, Lidia

    2013-01-01

    This study analyses the durability of rammed-earth wall construction techniques. The analysis focuses on three medieval masonry types from the Castle of Villavieja (Castellón, Spain) using two variations of lime-reinforced rammed earth in its walls: lime-crusted rammed earth and brick-reinforced rammed earth. Materials analysis reveals the good properties of the materials used in the outer wall facing despite its age. It also clearly shows how deterioration depends more on the construction t...

  15. Recycled sand in lime-based mortars.

    Science.gov (United States)

    Stefanidou, M; Anastasiou, E; Georgiadis Filikas, K

    2014-12-01

    The increasing awareness of the society about safe guarding heritage buildings and at the same time protecting the environment promotes strategies of combining principles of restoration with environmentally friendly materials and techniques. Along these lines, an experimental program was carried out in order to investigate the possibility of producing repair, lime-based mortars used in historic buildings incorporating secondary materials. The alternative material tested was recycled fine aggregates originating from mixed construction and demolition waste. Extensive tests on the raw materials have been performed and mortar mixtures were produced using different binding systems with natural, standard and recycled sand in order to compare their mechanical, physical and microstructure properties. The study reveals the improved behavior of lime mortars, even at early ages, due to the reaction of lime with the Al and Si constituents of the fine recycled sand. The role of the recycled sand was more beneficial in lime mortars rather than the lime-pozzolan or lime-pozzolan-cement mortars as a decrease in their performance was recorded in the latter cases due to the mortars' structure.

  16. Balancing guava nutrition with liming and fertilization

    Directory of Open Access Journals (Sweden)

    Amanda Hernandes

    2012-12-01

    Full Text Available Guava response to liming and fertilization can be monitored by tissue testing. Tissue nutrient signature is often diagnosed against nutrient concentration standards. However, this approach has been criticized for not considering nutrient interactions and to generate numerical biases as a result of data redundancy, scale dependency and non-normal distribution. Techniques of compositional data analysis can control those biases by balancing groups of nutrients, such as those involved in liming and fertilization. The sequentially arranged and orthonormal isometric log ratios (ilr or balances avoid numerical bias inherent to compositional data. The objectives were to relate tissue nutrient balances with the production of "Paluma" guava orchards differentially limed and fertilized, and to adjust the current patterns of nutrient balance with the range of more productive guava trees. It was conducted one experiment of 7-yr of liming and three experiments of 3-yr with N, P and K trials in 'Paluma' orchards on an Oxisol. Plant N, P, K, Ca and Mg were monitored yearly. It was selected the [N, P, K | Ca, Mg], [N, P | K], [N | P] and [Ca | Mg] balances to set apart the effects of liming (Ca-Mg and fertilizers (N-K on macronutrient balances. Liming largely influenced nutrient balances of guava in the Oxisol while fertilization was less influential. The large range of guava yields and nutrient balances allowed defining balance ranges and comparing them with the critical ranges of nutrient concentration values currently used in Brazil and combined into ilr coordinates.

  17. A Raman spectroscopic comparison of calcite and dolomite.

    Science.gov (United States)

    Sun, Junmin; Wu, Zeguang; Cheng, Hongfei; Zhang, Zhanjun; Frost, Ray L

    2014-01-03

    Raman spectroscopy was used to characterize and differentiate the two minerals calcite and dolomite and the bands related to the mineral structure. The (CO3)(2-) group is characterized by four prominent Raman vibrational modes: (a) the symmetric stretching, (b) the asymmetric deformation, (c) asymmetric stretching and (d) symmetric deformation. These vibrational modes of the calcite and dolomite were observed at 1440, 1088, 715 and 278 cm(-1). The significant differences between the minerals calcite and dolomite are observed by Raman spectroscopy. Calcite shows the typical bands observed at 1361, 1047, 715 and 157 cm(-1), and the special bands at 1393, 1098, 1069, 1019, 299, 258 and 176 cm(-1) for dolomite are observed. The difference is explained on the basis of the structure variation of the two minerals. Calcite has a trigonal structure with two molecules per unit cell, and dolomite has a hexagonal structure. This is more likely to cause the splitting and distorting of the carbonate groups. Another cause for the difference is the cation substituting for Mg in the dolomite mineral.

  18. Dolomite limits acidification of a biofilter degrading dimethyl sulphide

    Science.gov (United States)

    Smet; Van Langenhove H; Philips

    1999-01-01

    The applicability of dolomite particles to control acidification in a Hyphomicrobium MS3 inoculated biofilter removing dimethyl sulphide (Me2S) was studied. While direct inoculation of the dolomite particles with the liquid microbial culture was not successful, start-up of Me2S-degradation in the biofilter was observed when the dolomite particles were mixed with 33% (wt/wt) of Hyphomicrobium MS3-inoculated compost or wood bark material. Under optimal conditions, an elimination capacity (EC) of 1680 g Me2S m(-3) d(-1) was obtained for the compost/dolomite biofilter. Contrary to a wood bark or compost biofilter, no reduction in activity due to acidification was observed in these biofilters over a 235 day period because of the micro environment neutralisation of the microbial metabolite H2SO4 with the carbonate in the dolomite material. However, performance of the biofilter decreased when the moisture content of the mixed compost/dolomite material dropped below 15%. Next to this, nutrient limitation resulted in a gradual decrease of the EC and supplementation of a nitrogen source was a prerequisite to obtain a long-term high EC (> 250 g Me2S m(-3) d(-1)) for Me2S. In relation to this nitrogen supplementation, it was observed that stable ECs for Me2S were obtained when this nutrient was dosed to the biofilter at a Me2S-C/NH4Cl-N ratio of about 10.

  19. 准噶尔盆地西北缘风城组白云岩成因及油气富集因素%Dolomites genesis and hydrocarbon enrichment of the Fengcheng Formation in the northwestern margin of Junggar Basin

    Institute of Scientific and Technical Information of China (English)

    冯有良; 张义杰; 王瑞菊; 张光亚; 吴卫安

    2011-01-01

    Using the data of cores, well logging interpretations, seismic sections and experimental geochemistry, this paper analyzes the sedimentary environment, genesis, and distribution of dolomites, as well as the hydrocarbon enrichment factors of dolomite reservoirs in the Permian Fengcheng Formation. According to attitude and structure, the dolomites of the Fengcheng Formation are divided into lamina dolomites, thin-bed dolomites, and spotted dolomites. They are mainly the penecontemporaneous and epigenetic dolomites, the former was deposited in a saline semi-deep lake, while the latter results from the dolomitization of lime mud that was deposited in a saline semi-deep lake during the diagenetic stage. The dolomites are distributed at the palaeoslopes formed by volcano eruption and movement of thrust faults and the main dolomite reservoir spaces are dissolved pores and fractures. The factors controlling hydrocarbon enrichment are fractures and structural background.%利用钻井、岩心、地震、测井及地球化学资料,分析准噶尔盆地西北缘二叠系风城组白云岩沉积环境、成因、分布规律及白云岩储集层油气富集高产因素.风城组白云岩按产状和沉积构造可分为纹层状泥质白云岩、薄层状白云岩和斑状白云岩,主要为准同生白云岩和后生白云石化白云岩.准同生白云岩形成于半深湖咸水环境;后生白云石化白云岩是发育在半深湖咸水环境下的碳酸盐岩灰泥在成岩期经后生白云石化作用形成.白云岩主要分布在火山喷发或逆冲断裂活动形成的古地貌斜坡上.白云岩储集层的储集空间主要为溶蚀孔隙和裂隙.白云岩储集层富集高产的控制因素是裂缝及构造背景.

  20. Biomineralization of dolomite and magnesite discovered in tropical coralline algae: a biological solution to the geological dolomite problem

    Directory of Open Access Journals (Sweden)

    M. C. Nash

    2011-06-01

    Full Text Available Dolomite is a magnesium-rich carbonate mineral abundant in fossil carbonate reef platforms but surprisingly rare in modern sedimentary environments, a conundrum known as the ''Dolomite Problem". Marine sedimentary dolomite has been interpreted to form by an unconfirmed, post-depositional diagenetic process, despite minimal experimental success at replicating this. Here we show that dolomite, accompanied by magnesite, forms within living crustose coralline alga, Hydrolithon onkodes, a prolific global tropical reef species. Chemical micro-analysis of the coralline skeleton reveals that not only are the cell walls calcitised, but that cell spaces are typically filled with magnesite, rimmed by dolomite, or both. Mineralogy was confirmed by X-ray diffraction. Thus there are at least three mineral phases present (magnesium calcite, dolomite and magnesite rather than one or two (magnesium calcite and brucite as previously thought. Our results are consistent with dolomite occurrences in coralline algae rich environments in fossil reefs. Instead of a theory of post-depositional dolomitisation, we present evidence revealing biomineralization that can account for the massive formations seen in the geologic record. Additionally, our findings imply that previously unrecognized dolomite and magnesite have formed throughout the Holocene. This discovery together with the scale of coralline algae dominance in past shallow carbonate environments raises the possibility that environmental factors driving this biological dolomitisation process have influenced the global marine magnesium/calcium cycle. Perhaps, most importantly, we reveal that what has been considered a geological process can be a biological process, having many implications for both disciplines.

  1. Mountain geomorphosites in Odle Group (Dolomites, Italy)

    Science.gov (United States)

    Coratza, Paola; Ghinoi, Alessandro; Marchetti, Mauro; Soldati, Mauro

    2016-04-01

    The area, considered in the present study, is located in the north-eastern sector of the Gardena valley, in the Odle Group, a popular destination of summer and winter tourism (more than 3000 m a.s.l.). The area has a strong hiking-tourism vocation thanks to its spectacular high-mountain landscape and a dense network of hiking tracks. The well-developed network of hiking paths and slopes for many different climbing skills offers a lot of possibilities for high-mountain excursions. Permanent dwelling-places are absent with the exceptions of a few tourist structures nearby opened during certain periods of the year. This area, as all Dolomites, which became UNESCO Word Heritage Site in 2009, represent landscape mosaics, which express the summation of landscape histories and processes offering an almost complete educational open-air laboratory due to the variety and complexity of phenomena and processes taking place during present climate conditions and during recent geological periods. These mountains, due to the aggregation of relict, recent and active landforms constitute an outstanding geoheritage, suitable for educational and tourist purposes. Landforms typical of past morphoclimatic conditions (inherited geomorphosites) share the stage with forms and processes active in the current morphoclimatic conditions (active geomorphosites); their spatial and geometrical relationships may be sufficient to trace a relative time-line of the geomorphological history of the area. Several glacial landforms testify for the presence and the activity of a glacial tongue hosted in the valley during the Lateglacial, mainly located in the northern sector of the area, where altitudes range from about 2000 m to about 2300 m a.s.l. Among these, worth of note are the well-preserved glacial cirques of Val dla Roa and those located at the southern margin of the Odle Group. Quite well preserved moraine ridges are present at a mean altitude of some 2000 m at the Alpe di Cisles as well as

  2. Dolomitized bryozoan bioherms from the Lower Silurian Manitoulin Formation, Bruce Peninsula, Ontario

    Energy Technology Data Exchange (ETDEWEB)

    Anastas, A.S.; Coniglo, M. (Waterloo Univ., ON (Canada))

    1992-06-01

    Several small, previously undescribed bioherms are present in the shallow shelf dolostones of the Manitoulin Formation at the Cabot Head and Wingfield Basin localities in the northernmost portion of the Bruce Peninsula region of southern Ontario. The bioherms, commonly associated with carbonate tempestites, range from 0.3 to 1.0 m in height and 0.9 to 2.5 m in width and are composed of bafflestones-floatstones and minor bindstones. The chief components of the bioherms are dolomitized lime mud and branching bryozoans. Bioherm building by bryozoans, although common in the ancient record, represents a great divergence from the mostly accessory frame encrusting role of bryozoans in modern environments. Minor skeletal components of the bioherms include echinoderms, rugose and tabulate corals and brachiopods. Laminar encrusting bryozoans exist in the top 10 cm of one of the bioherms. Some of the bioherms show evidence of water agitation that may be the result of current action induced by storm or tidal processes. The occurrence of the bioherms stretches the already known Llandoverian reef complex on Manitoulin Island further to the south. The reason why these bioherms did not reach sizes comparable to large Llandoverian or Wenlockian reefs and did not make the shift to coral-stromaporoid community is probably related to a complex interaction of factors such as community development, bathymetry, clasticity and salinity. 41 refs., 4 figs.

  3. Optimization of lime addition in a dry air pollution control device; Optimerad rening av HCl och SO{sub 2} med minskade kalktillsatser vid torr roeasrening

    Energy Technology Data Exchange (ETDEWEB)

    Wikstroem-Blomqvist, Evalena; Samuelsson, Jessica; Ohlsson, Anna

    2006-12-15

    The focus of this project is to optimize the absorption of hydrochloric acid (HCl) and sulphuric acid (SO{sub 2}) in a dry air pollution control device system connected to a waste combustor. A significant amount of absorbent are generally added into the processes to achieve an efficient cleaning of the flue gas. Reduced absorbent consumption has double benefits on the operative expenses due to decreased purchase and landfilling costs. The objective was to study the affect of flue gas temperature and moisture, (relative humidity, RH), on the efficiency of HCl and SO{sub 2} absorption on hydrated lime. Additionally, the efficiency of a pre-treated hydrated lime with larger specific surface and pore volume was investigated. The measuring campaign was conducted on the 20 MW fluidized bed waste incinerator own by Boraas Energi och Miljoe AB in Sweden. Results from 26 experimental days with normal hydrated lime showed a positive correlation between the efficiency of the lime and RH in the flue gas. Four levels of RH between 3.28% to 4.84% were tested. The levels were adjusted by lowering the flue gas temperature and/or by adding water to the waste fuel. The smallest effect where achieved by solely adding water to the waste fuel. RH increased solely to 3.62% and the amount of lime consumption was reduced with only 5% compare to normal condition. By lowering the flue gas temperature 10 deg C to 143 deg C, RH increased to 4.06% and the amount of lime added was reduced with 13%. The largest impact was found when both the flue gas temperature and the moisture content were changed. At those process conditions RH reach 4.84 % and the usage of lime were reduced with 26%. Additional 12 experimental days were conducted to evaluate the efficiency of a pretreated hydrated lime with larger specific surface and pore volume. The results showed that the surface enlarged absorbent was almost twice as effective as the normal hydrated lime. Moreover, the results indicated an equal

  4. The relative merits of dolomitic and calcitic limestone in detoxifying and revegetating acidic, nickel- and copper-contaminated soils in the Sudbury mining and smelting region of Canada

    Energy Technology Data Exchange (ETDEWEB)

    McHale, D.; Winterhalder, K. [Laurentian Univ., Sudbury, Ontario (Canada)

    1996-12-31

    Soils in the Sudbury mining and smelting region have been rendered phytotoxic and barren by acidification and Particulate metal contamination, but can be detoxified revegetated by the surface application of an growth is better on soil treated ground limestone. On certain barren sites, plant growth is better on soil treated with dolomitic limestone than with calcitic limestone and greenhouse experiments using mung beans (Vigna radiata) have shown superior root and shoot growth on certain contaminated soils when the limestone is dolomitic rather than calcitic. Results of experiments with species used in revegetation (Agrostis gigantea and Lotus corniculatus) suggest that leguminous species are more sensitive to Ca:Mg ratio than grasses, that the plant response to this ratio is greater at lowering liming levels, and that the response is more marked on more toxic soils. The effects of calcium:magnesium ratio of the limestone used in revegetating acidic, metal-contaminated soils are clearly complex, interactive and difficult to interpret. Further studies are needed, but meanwhile it is recommended that the practice of using dolomitic limestone to detoxify barren Sudbury soils be continued, since there is a risk of induced magnesium deficiency at certain sites when calcitic limestone is used.

  5. Basic Oxygen Furnace Slag as a Liming Agent for Paddy and Upland Field Soils

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Choong Il [Pohang Research Institute of Industrial Science and Technology, Pohang(Korea)

    1998-03-31

    Basic oxygen furnace (BOF) slag, a by-product of the iron and steelmaking industry produced in large quantities in Korea, poses a substantial disposal challenge. The BOF slag used in this study was 1/3 CaCO{sub 3} in total neutralizing power and application of 7-8 Mgha{sup -1} was needed to bring soil pH to 6.5 from pH 5.0-5.5 in silty clay or clay loam soil contained about 10% organic matter. A field assay was conducted to study whether BOF slag could be used as a dolomitic liming agent for agricultural soils. Four slag rates (0, 4, 8, 12 Mgha{sup -1})were investigated for their effect on soil properties, mineral concentrations in leaf tissues of rice and soybean, and yield of the crops. Slag application at 8 Mgha{sup -1} rate in paddy field increased pH, Ca, Mg, P, Si and Fe content in soil and rice yield by 4.3-14.2% depending on the soil type. In upland field the 8 Mgha{sup -1} rate increased pH, Ca and Fe content in soil and soybean yield by 36.6%. Thus, BOF slag appears to be a useful liming material for correcting soil acidity on both paddy and upland field soils and for increasing Ca, Mg, P, Si, and Fe concentration in plants. (author). 27 refs., 7 tabs.

  6. Phosphorus availability in oxidic soils treated with lime and silicate applications

    Directory of Open Access Journals (Sweden)

    Aline da Silva Sandim

    2014-08-01

    Full Text Available Based on the assumption that silicate application can raise soil P availability for crops, the aim of this research was to compare the effect of silicate application on soil P desorption with that of liming, in evaluations based on two extractors and plant growth. The experiment was carried out in randomized blocks with four replications, in a 3 × 3 × 5 factorial design, in which three soil types, three P rates, and four soil acidity correctives were evaluated in 180 experimental plots. Trials were performed in a greenhouse using corn plants in 20-dm³ pots. Three P rates (0, 50 and 150 mg dm-3 were applied in the form of powder triple superphosphate and the soil was incubated for 90 days. After this period, soil samples were collected for routine chemical analysis and P content determination by the extraction methods resin, Mehlich-1 and remaining P. Based on the results, acidity correctives were applied at rates calculated for base saturation increased to 70 %, with subsequent incubation for 60 more days, when P content was determined again. The acidity correctives consisted of: dolomitic lime, steelmaking slag, ladle furnace slag, and wollastonite. Therefore, our results showed that slags raised the soil P content more than lime, suggesting a positive correlation between P and Si in soil. Silicon did not affect the extractor choice since both Mehlich-1 and resin had the same behavior regarding extracted P when silicon was applied to the soil. For all evaluated plant parameters, there was significant interaction between P rates and correctives; highest values were obtained with silicate.

  7. Thermodynamic Modelling of Dolomite Behavior in Aqueous Media

    Directory of Open Access Journals (Sweden)

    Tadeusz Michałowski

    2012-01-01

    Full Text Available The compact thermodynamic approach to the systems containing calcium, magnesium, and carbonate species is referred to dissolution of dolomite, as an example of nonequilibrium ternary salt when introduced into aqueous media. The study of dolomite is based on all attainable physicochemical knowledge, involved in expressions for equilibrium constants, where the species of the system are interrelated. The species are also involved in charge and concentration balances, considered as constraints put on a closed system, separated from the environment by diathermal walls. The inferences are gained from calculations performed with use of an iterative computer program. The simulated quasistatic processes occurred under isothermal conditions, started at a preassumed pH0 value of the solution where dolomite was introduced, and are usually involved with formation of other solid phases. None simplifying assumptions in the calculations were made.

  8. Hydrogen Chloride Reaction with Lime and Limestone

    DEFF Research Database (Denmark)

    Erik Weinell, Claus; Jensen, Peter I.; Dam-Johansen, Kim

    1992-01-01

    The capacity of solid slaked lime and limestone for binding HCl from a gas phase has been investigated in the temperature range 60-1000 °C. The binding capacity is largest in the range 500-600 °C. However, for slaked lime in the presence of water, a large binding capacity is observed also below 150...... °C. This is ascribed to the formation of a partially liquid product phase. At temperatures exceeding 500 °C the binding capacity is limited by chemical equilibrium between gas and solid. For the range of properties studied the binding capacity is independent of particle size and only depends slightly...

  9. Self-diffusion of carbon and oxygen in dolomite.

    Science.gov (United States)

    Anderson, T. F.

    1972-01-01

    Self-diffusion of carbon and oxygen in dolomite was measured by isotopic exchange with CO2 at 645-785 C at 120-935 bars pressure. Several runs were also made with calcite under comparable experimental conditions. The principal findings of this study are that (1) the self-diffusion coefficients of both carbon and oxygen in dolomite are approximately 100 times larger than the values in calcite over the temperature range investigated and (2) oxygen self-diffusion in calcite is accelerated by high CO2 pressure.

  10. Mechanism of separating pyrite and dolomite by flotation

    Institute of Scientific and Technical Information of China (English)

    Anping Liu; Wen Ni; Wei Wu

    2007-01-01

    To study the mechanism of separating pyrite and dolomite by flotation, the acting mechanisms of WHL depressor and both the minerals were studied by means of thermogravimetric and differential thermal analysis (TG-DTA), Fourier transform infrareddiffuse reflection spectroscopy (FTIR-DRS), and X-ray photoelectron spectroscopy (XPS). The results indicated that WHL formed metal salts with metal ions dissolved in water from dolomite and pyrite, which then deposited on their surfaces. Both of the minerals could be depressed by WHL. In the process of flotation, sulfur was created besides the WHL being absorbed on the surface of the sulfur concentrate, and its recovery rate was slightly affected.

  11. Diagenetic setting, dolomitization and reservoir characterization of Late Cretaceous Kawagarh Formation, Khanpur Dam section, Hazara, Pakistan

    Directory of Open Access Journals (Sweden)

    Maqsood Ur Rahman

    2016-12-01

    Full Text Available The Kawagarh Formation is well exposed in Hazara basin in different sections. Due to deep depositional settings, the Kawagarh Formation is least appealing to geologists to investigate it as a hydrocarbon reservoir. In the present study, the diagenetic settings of Kawagarh Formation were chronologically studied to interpret its diagenetic history and the effect of different diagenetic phases on the reservoir potential. The dolomitization is also studied in depth to use it as a key for its reservoir potential. Kawagarh Formation is sampled at Khanpur Dam Section for porosity analysis. The samples were taken from limestone and dolomite facies randomly. The dolomites are in the form of veins and well developed thick size beds. These dolomites are secondary in nature which is hosted by fractures and joints of limestone, which affect about 25% of limestone facies. At outcrop scale different types of dolomites are recognised on the basis of color and texture, yellowish fine-grained, brown blackish coarse-grained in the top portion and saddle dolomites. In petrographic study partial and complete dolomitization are observed. On the basis of crystal sizes and geometry different types of dolomites are recognized which are; (1 fine crystalline planar-euhedral dolomite, (2 medium crystalline planar-subhedral dolomite, (3 medium crystalline non-planar-anhedral dolomite, (4 coarse crystalline planar-subhedral dolomite, (5 coarse crystalline, non-planar-anhedral dolomite and (6 saddle dolomites (SD1. In petrographic study, high inclusions and disturbance are observed at the surfaces of dolomitic rhombs which indicate low Mg replacement or dedolomitization phenomena. On image J porosity analysis, the porosity is found of limestone and dolomitic samples. In limestone facies which is mostly, non-laminated mudstone has very low up to 2 to 3% in the form of vugs and fractures. In dolomitic facies, the porosity is ranging from 5% to 14%. In most of the dolomitic

  12. 27 CFR 9.27 - Lime Kiln Valley.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Lime Kiln Valley. 9.27... OF THE TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.27 Lime Kiln Valley. (a) Name. The name of the viticultural area described in this section is “Lime Kiln...

  13. 46 CFR 148.04-23 - Unslaked lime in bulk.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Unslaked lime in bulk. 148.04-23 Section 148.04-23... HAZARDOUS MATERIALS IN BULK Special Additional Requirements for Certain Material § 148.04-23 Unslaked lime in bulk. (a) Unslaked lime in bulk must be transported in unmanned, all steel, double-hulled...

  14. Microstructure evolution of lime putty upon aging

    Science.gov (United States)

    Mascolo, Giuseppe; Mascolo, Maria Cristina; Vitale, Alessandro; Marino, Ottavio

    2010-08-01

    The microstructure evolution of lime putty upon aging was investigated by slaking quicklime (CaO) with an excess of water for 3, 12, 24, 36, 48 and 66 months. The as-obtained lime putties were characterized in the water retention and in the particle size distribution using the static laser scattering (SLS). The same lime putties, dehydrated by lyophilization, were also investigated in the pore size distribution by mercury intrusion porosimetry, in the surface area by the BET method and, finally, in particle morphology by scanning electron microscopy (SEM). The effect of the extended exposure of quicklime to water confirms a shape change from prismatic crystals of portlandite, Ca(OH) 2, into platelike ones. Simultaneously a growth of larger hexagonal crystals at the expense of the smallest ones (Ostwald ripening) favours a secondary precipitation of submicrometer platelike crystals of portlandite. The shape change and the broader particles size distribution of portlandite crystals upon aging seem to contribute to a better plasticity of lime putty.

  15. Fertilizer and Lime: Why They Are Used.

    Science.gov (United States)

    McCaslin, Judith Strand

    This unit teaching guide is designed to help teachers explain the principles of fertilizer and lime use. The first of four major sections is a teaching outline keyed to transparency masters and student handouts. Thirteen major areas are covered in the teaching outline: (1) plant needs; (2) uses of fertilizer; (3) nutrients for plant growth; (4)…

  16. Oxidative lime pretreatment of Alamo switchgrass.

    Science.gov (United States)

    Falls, Matthew; Holtzapple, Mark T

    2011-09-01

    Previous studies have shown that oxidative lime pretreatment is an effective delignification method that improves the enzymatic digestibility of many biomass feedstocks. The purpose of this work is to determine the recommended oxidative lime pretreatment conditions (reaction temperature, time, pressure, and lime loading) for Alamo switchgrass (Panicum virgatum). Enzymatic hydrolysis of glucan and xylan was used to determine the performance of the 52 studied pretreatment conditions. The recommended condition (110°C, 6.89 bar O(2), 240 min, 0.248 g Ca(OH)(2)/g biomass) achieved glucan and xylan overall yields (grams of sugar hydrolyzed/100 g sugar in raw biomass, 15 filter paper units (FPU)/g raw glucan) of 85.9 and 52.2, respectively. In addition, some glucan oligomers (2.6 g glucan recovered/100 g glucan in raw biomass) and significant levels of xylan oligomers (26.0 g xylan recovered/100 g xylan in raw biomass) were recovered from the pretreatment liquor. Combining a decrystallization technique (ball milling) with oxidative lime pretreatment further improved the overall glucan yield to 90.0 (7 FPU/g raw glucan).

  17. The mechanical and microstructural behaviour of calcite-dolomite composites: An experimental investigation

    OpenAIRE

    Kushnir, Alexandra R. l.; Kennedy, L. A.; Misra, Santanu; Benson, Philip; White, J C

    2015-01-01

    The styles and mechanisms of deformation associated with many variably dolomitized limestone shear systems are strongly controlled by strain partitioning between dolomite and calcite. Here, we present experimental results from the deformation of four composite materials designed to address the role of dolomite on the strength of limestone. Composites were synthesized by hot isostatic pressing mixtures of dolomite (Dm) and calcite powders (% Dm: 25%-Dm, 35%-Dm, 51%-Dm, and 75%-Dm). In all comp...

  18. First discovery of dolomite and magnesite in living coralline algae and its geobiological implications

    OpenAIRE

    M. C. Nash; Troitzsch, U; B. N. Opdyke; Trafford, J. M.; Russell, B. D.; Kline, D. I.

    2011-01-01

    Dolomite is a magnesium-rich carbonate mineral abundant in fossil carbonate reef platforms but surprisingly rare in modern sedimentary environments, a conundrum known as the "Dolomite Problem". Marine sedimentary dolomite has been interpreted to form by an unconfirmed, post-depositional diagenetic process, despite minimal experimental success at replicating this. Here we show that dolomite, accompanied by magnesite, forms within living crustose coralline alga, Hydrolithon onkodes<...

  19. PHOSPHORUS REMOVAL IN A VERTICAL FLOW CONSTRUCTED WETLAND USING DOLOMITE POWDER AND CHIPPINGS AS FILTER MEDIA

    OpenAIRE

    Gražina Žibienė; Midona Dapkienė; Jurgita Kazakevičienė; Algirdas Radzevičius

    2015-01-01

    Different kinds of natural and artificial filter media are able to retain phosphorus in the constructed wetlands. Due to the fact that the constructed wetland needs huge amounts of the filter media, it is very important to find locally available material which distinguishes itself by its ability to retain phosphorus. The materials found in Lithuania were considered and dolomite was chosen. Two dolomite fractions, dolomite powder (1–2 mm) and dolomite chippings (2–5 mm), and sand media were us...

  20. Phosphorus leaching in soils amended with piggery effluent or lime residues from effluent treatment.

    Science.gov (United States)

    Weaver, D M; Ritchie, G S

    1994-01-01

    Phosphorus (P) in wastes from piggeries may contribute to the eutrophication of waterways if not disposed of appropriately. Phosphorus leaching, from three soils with different P sorption characteristics (two with low P retention and one with moderate P retention) when treated with piggery effluent (with or without struvite), was investigated using batch and leaching experiments. The leaching of P retained in soil from the application of struvite effluent was determined. In addition, P leaching from lime residues (resulting from the treatment of piggery effluent with lime to remove P) was determined in comparison to superphosphate when applied to the same three soils. Most P was leached from sandy soils with low P retention when effluent with or without struvite was applied. More than 100% of the filterable P applied in struvite effluent was leached in sandy soils with low P retention. Solid, inorganic forms of P (struvite) became soluble and potentially leachable at pHdissolution if there were sufficient sorption sites. In sandy soils with low P retention, more than 39% of the total filterable P applied in recycled effluent (without struvite) was leached. Soil P increased mainly in surface layers after treatment with effluent. Sandy soils pre-treated with struvite effluent leached 40% of the P retained in the previous application. Phosphorus decreased in surface layers and increased at depth in the soil with moderate P retention after leaching the struvite effluent pre-treated soil with water. The soils capacity to adsorb P and the soil pH were the major soil properties that affected the rate and amount of P leaching, whereas the important characteristics of the effluent were pH, P concentration and the forms of P in the effluent. Phosphorus losses from soils amended with hydrated lime and lime kiln dust residues were much lower than losses from soils amended with superphosphate. Up to 92% of the P applied as superphosphate was leached from sandy soils with low P

  1. A mild alkali treated jute fibre controlling the hydration behaviour of greener cement paste

    Science.gov (United States)

    Jo, Byung-Wan; Chakraborty, Sumit

    2015-01-01

    To reduce the antagonistic effect of jute fibre on the setting and hydration of jute reinforced cement, modified jute fibre reinforcement would be a unique approach. The present investigation deals with the effectiveness of mild alkali treated (0.5%) jute fibre on the setting and hydration behaviour of cement. Setting time measurement, hydration test and analytical characterizations of the hardened samples (viz., FTIR, XRD, DSC, TGA, and free lime estimation) were used to evaluate the effect of alkali treated jute fibre. From the hydration test, the time (t) required to reach maximum temperature for the hydration of control cement sample is estimated to be 860 min, whilst the time (t) is measured to be 1040 min for the hydration of a raw jute reinforced cement sample. However, the time (t) is estimated to be 1020 min for the hydration of an alkali treated jute reinforced cement sample. Additionally, from the analytical characterizations, it is determined that fibre-cement compatibility is increased and hydration delaying effect is minimized by using alkali treated jute fibre as fibre reinforcement. Based on the analyses, a model has been proposed to explain the setting and hydration behaviour of alkali treated jute fibre reinforced cement composite.

  2. Sporicidal characteristics of heated dolomite powder against Bacillus subtilis spores.

    Science.gov (United States)

    Yasue, Syogo; Sawai, Jun; Kikuchi, Mikio; Nakakuki, Takahito; Sano, Kazuo; Kikuchi, Takahide

    2014-01-01

    Dolomite is a double salt composed of calcium carbonate (CaCO3) and magnesium carbonate (MgCO3). The heat treatment of CaCO3 and MgCO3 respectively generates calcium oxide (CaO) and magnesium oxide (MgO), which have antimicrobial activity. In this study, heated dolomite powder (HDP) slurry was investigated for its sporicidal activity against Bacillus subtilis ATCC 6633 spores. The B. subtilis spores used in this study were not affected by acidic (pH 1) or alkaline (pH 13) conditions, indicating that they were highly resistant. However, dolomite powder heated to 1000℃ for 1 h could kill B. subtilis spores, even at pH 12.7. Sporicidal activity was only apparent when the dolomite powder was heated to 800℃ or higher, and sporicidal activity increased with increases in the heating temperature. This temperature corresponded to that of the generation of CaO. We determined that MgO did not contribute to the sporicidal activity of HDP. To elucidate the sporicidal mechanism of the HDP against B. subtilis spores, the generation of active oxygen from HDP slurry was examined by chemiluminescence analysis. The generation of active oxygen increased when the HDP slurry concentration rose. The results suggested that, in addition to its alkalinity, the active oxygen species generated from HDP were associated with sporicidal activity.

  3. Gravity tectonics in the Northwestern Dolomites (N. Italy)

    NARCIS (Netherlands)

    Engelen, G.B.

    1963-01-01

    The NW Dolomites (see fig. 1 and 2) have an area of approximately 1500 sq. km and are situated on the southern flank of the east alpine mountain range. The region consists mainly of permo-triassic and some younger mesozoic strata with a maximal thickness of about 3000 m. This sedimentary series was

  4. Processes and controlling factors of polygenetic dolomite formation in the Transdanubian Range, Hungary: a synopsis

    Science.gov (United States)

    Haas, János; Hips, Kinga; Budai, Tamás; Győri, Orsolya; Lukoczki, Georgina; Kele, Sándor; Demény, Attila; Poros, Zsófia

    2016-06-01

    In the Transdanubian Range (Hungary), dolostone and dolomitic limestone appear in a number of sedimentary successions formed from the Late Permian to the Late Triassic in various depositional settings and under various diagenetic conditions, whereas only a negligible amount of dolomite was detected in the post-Triassic formations. Seven dolomite-bearing units representing ramp, small and large carbonate platforms, and intraplatform basin settings are presented in this synopsis. In most cases, multi-stage and polygenetic dolomitization was inferred. The main mass of the dolostones was formed via near-surface diagenetic processes, which were commonly preceded by the formation of synsedimentary dolomite. Accordingly, surficial conditions that prevailed during sediment deposition controlled the dolomite-forming processes and thus the lateral extension and the time span of dolomitization. The area of episodic subaerial exposure was a critical controlling factor of the lateral extension of the near-surface dolomite genesis, whereas its temporal extension was mostly governed by climate. Burial diagenesis usually resulted in only moderate dolomitization, either in connection with compactional fluid flow or via thermal convection. The Triassic fault zones provided conduits for fluid flow that led to both replacive dolomitization and dolomite cement precipitation. In the Late Triassic extensional basins, synsedimentary fault-controlled dolomitization of basinal deposits was reconstructed.

  5. Origins of hydration lubrication.

    Science.gov (United States)

    Ma, Liran; Gaisinskaya-Kipnis, Anastasia; Kampf, Nir; Klein, Jacob

    2015-01-14

    Why is friction in healthy hips and knees so low? Hydration lubrication, according to which hydration shells surrounding charges act as lubricating elements in boundary layers (including those coating cartilage in joints), has been invoked to account for the extremely low sliding friction between surfaces in aqueous media, but not well understood. Here we report the direct determination of energy dissipation within such sheared hydration shells. By trapping hydrated ions in a 0.4-1 nm gap between atomically smooth charged surfaces as they slide past each other, we are able to separate the dissipation modes of the friction and, in particular, identify the viscous losses in the subnanometre hydration shells. Our results shed light on the origins of hydration lubrication, with potential implications both for aqueous boundary lubricants and for biolubrication.

  6. LIME mediates immunological synapse formation through activation of VAV.

    Science.gov (United States)

    Son, Myoungsun; Park, Inyoung; Lee, Ok-Hee; Rhee, Inmoo; Park, Changwon; Yun, Yungdae

    2012-04-01

    Lck Interacting Membrane protein (LIME) was previously characterized as a transmembrane adaptor protein mediating TCR-dependent T cell activation. Here, we show that LIME associates with Vav in response to TCR stimulation and is required for Vav guanine nucleotide exchange factor (GEF) activity for Rac1. Consistent with this finding, actin polymerization at the immunological synapse (IS) was markedly enhanced by overexpression of LIME, but was reduced by expression of a LIME shRNA. Moreover, TCR-mediated cell adhesion to ICAM-1, laminin, or fibronectin was downregulated by expression of LIME shRNA. In addition, in the IS, LIME but not LAT was found to localize at the peripheral-supramolecular activation cluster (p-SMAC) where the integrins were previously shown to be localized. Together, these results establish LIME as a transmembrane adaptor protein linking TCR stimulation to IS formation and integrin activation through activation of Vav.

  7. Thermal decomposition of dolomite under CO2-air atmosphere

    Science.gov (United States)

    Subagjo, Wulandari, Winny; Adinata, Pratitis Mega; Fajrin, Anita

    2017-01-01

    This paper reports a study on thermal decomposition of dolomite under CO2-air. Calcination was carried out non-isothermally by using thermogravimetry analysis-differential scanning calorimetry (TGA-DSC) with a heating rate of 10°C/minute in an air atmosphere as well as 10 vol% CO2 and 90 vol% air atmosphere from 25 to 950°C. In addition, a thermodynamic modeling was also carried out to simulate dolomite calcination in different level of CO2-air atmosphere by using FactSage® 7.0. The the main constituents of typical dolomite from Gresik, East Java include MgCO3 (magnesite), CaCO3 (calcite), Ca(OH)2, CaO, MgO, and less than 1% of metal impurities. Based on the kinetics analysis from TGA results, it is found that non-isothermal dolomite calcination in 10 vol% CO2 atmosphere is occurred in a two-stage reaction; the first stage is the decomposition of magnesite at 650-740 °C with activation energy of 161.23 kJ/mol, and the second stage is the decomposition of calcite at 775-820 °C with activation energy of 162.46 kJ/mol. The magnesite decomposition is found to follow nucleation reaction mechanism of Avrami Eroveyef (A3), while calcite decomposition follows second order chemical reaction equation. Thermodynamic modeling supports these kinetic analyses. The results of this research give insight to the kinetics of dolomite decomposition in CO2-air atmosphere.

  8. The advances in the study of microbial dolomite%微生物成因白云石研究进展

    Institute of Scientific and Technical Information of China (English)

    王宁

    2011-01-01

    "Dolomite problem" has long been one of the focuses and difficulties in the study of sedimentary geology. Dolomite serves as an important reservoir of oil and gas both in China and abroad. Therefore, the understanding of the formation process of dolomite is significant for the exploration of oil and gas in carbonate rocks. There are many models to explain the origin of dolomite, such as the Sabhka evaporation model, the seepage-reflux model, the burial adjustment model, the mixing zone model, and the tidal pumping model. During the past decades, with the further research on the dolomite formation at low temperature, the microbial dolomite model, as a new dolomite origin model, was proposed and well developed. This paper reviews the progress of research on microbial dolomite. Three kinetic barriers of dolomite precipitation under earth surface conditions were listed, which are strong hydration energy of magnesium ion, the existence of sulfate ion and the low concentration and low activity of carbonate ion. The background for putting forward the microbial dolomite model and the growth process and morphological characteristics of microbial dolomite were briefly described. The mediation of microbeduring the formation process of dolomite was explained in detail. It is pointed out that the existence of microbes (e. G., sulfate-reducing bacteria and ancient methane bacteria) could change the ion balance of solution and help dolomite to overcome the kinetic barriers during the precipitation process. The application of oxygen isotope of microbial dolomite to the reconstruction of palaeo-temperature and ancient climate change was discussed. The future orientations for research on microbial dolomite (e. G., multidisciplinary analysis, application of high technology etc.) were predicated. The further investigation into the microbial dolomite model will provide researchers with a new approach to understanding the "dolomite problem" and is also helpful to the study of dolomite

  9. Investigation of the Role of Polysaccharide in the Dolomite Growth at Low Temperature by Using Atomistic Simulations.

    Science.gov (United States)

    Shen, Zhizhang; Szlufarska, Izabela; Brown, Philip E; Xu, Huifang

    2015-09-29

    Dehydration of water from surface Mg(2+) is most likely the rate-limiting step in the dolomite growth at low temperature. Here, we investigate the role of polysaccharide in this step using classical molecular dynamics (MD) calculations. Free energy (potential of mean force, PMF) calculations have been performed for water molecules leaving the first two hydration layers above the dolomite (104) surface under the following three conditions: without catalyst, with monosaccharide (mannose), and with oligosaccharide (three units of mannose). MD simulations reveal that there is no obvious effect of monosaccharide in lowering the dehydration barrier for surface Mg(2+). However, we found that there are metastable configurations of oligosaccharide, which can decrease the dehydration barrier of surface Mg(2+) by about 0.7-1.1 kcal/mol. In these configurations, the molecule lies relatively flat on the surface and forms a bridge shape. The hydrophobic space near the surface created by the nonpolar -CH groups of the oligosaccharide in the bridge conformation is the reason for the observed reduction of dehydration barrier.

  10. Physical-mechanical characterization of hydraulic and non-hydraulic lime based mortars for a French porous limestone

    CERN Document Server

    Al-Mukhtar, M

    2006-01-01

    The focus of the study presented in this paper is to provide reliable criteria that can be used to estimate the degree of compatibility between the French limestone tuffeau and mortar. It is suggested through this study to use the same parent material (i.e., tuffeau) as mortar. The mortar used in this study is composed of non-hydraulic (hydrated) lime or hydraulic lime and aggregates obtained from fragments and powder of the tuffeau stone. Water transfer properties and mechanical behaviour of the mortars are evaluated and compared with the original stone Tuffeau. Based on these studies, some key guidelines are provided such that a mortar that is compatible with properties of Tuffeau and can be prepared and used as construction material of monuments and maintenance purposes.

  11. Hydrothermal recrystallization of the Lower Ordovician dolomite and its significance to reservoir in northern Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Discovered in S15 and some other wells, the Lower Ordovician in the northern Tarim Basin consists mainly of brown gray-dark gray very fine-fine crystalline dolomite, with a minor portion of locally light gray-white medium-coarse crystalline dolomite. Silicification can be observed in the medium-coarse dolomite, and some euhedral drusy quartz can also be found in pores and fractures of the dolomite. The homogenization temperature of the fluid inclusions in the medium-coarse dolomite is between 110 and 200°C with maximum between 140 and 190°C, and the salinity is between 10.7 and 18.5 wt.% NaCl Eq. The homogenization temperature and salinity of the fluid inclusions in the medium-coarse dolomite are similar to those in the drusy quartz. Compared with the very fine-fine dolomite, the medium-coarse phase contains relatively high Fe and Mn. The average concentration of FeO and MnO in the medium-coarse dolomite is 1.917% and 0.323%, respectively. The medium-coarse dolomite has a remarkable negative Eu anomaly, consistent with the REE pattern of the intermediate-felsic igneous rocks in the Tarim Basin. The oxygen isotopic composition of the medium-coarse dolomite is relatively lighter than that of the very fine-fine dolomite. The δ18OPDB values of the medium-coarse dolomite are between -10.35‰ and -7.31‰. The δ18OSMOW values of the fluid associated with the medium-coarse dolomite can be calculated according to homogenization temperature and oxygen isotope fractionation factor between dolomite and fluid, and the calculated values are between +4‰ and +10‰, consistent with those of the hydrothermal fluid. The medium-coarse dolomite has relatively high 87Sr/86Sr ratios as well, indi- cating an origin associated with intermediate-felsic igneous rock. The homogenization temperature, element composition, REE pattern, oxygen and strontium isotopes demonstrate that the medium-coarse dolomite is the result of recrystallization of very fine-fine dolomite under

  12. Terrestrial Liming As a Restoration Technique for Acidified Forest Ecosystems

    Directory of Open Access Journals (Sweden)

    Sarah E. Pabian

    2012-01-01

    Full Text Available We studied the effects of liming on soils and forest songbirds as well as vegetation and calcium-rich invertebrate prey variables that were predicted to link birds to changes in soil conditions. We observed increases in soil pH, calcium, and magnesium, as well as in songbird abundances in response to lime application, with continuing increases through five years after liming. We observed an overall increase in snail abundance on limed sites, but an initial peak of a 23 fold increase three years after liming was reduced to an 11 fold increase five years after liming. We observed an increase in forb ground cover on limed sites, but liming had no effect on millipede abundance or other vegetation measures. Of the variables we measured, snail abundance was the most likely mechanism for the response in bird abundances. Because we observed continued benefits of liming up to five years post treatment, we concluded that liming is a very promising technique for restoring forest ecosystems impacted by acidic deposition.

  13. First discovery of dolomite and magnesite in living coralline algae and its geobiological implications

    Directory of Open Access Journals (Sweden)

    M. C. Nash

    2011-11-01

    Full Text Available Dolomite is a magnesium-rich carbonate mineral abundant in fossil carbonate reef platforms but surprisingly rare in modern sedimentary environments, a conundrum known as the "Dolomite Problem". Marine sedimentary dolomite has been interpreted to form by an unconfirmed, post-depositional diagenetic process, despite minimal experimental success at replicating this. Here we show that dolomite, accompanied by magnesite, forms within living crustose coralline alga, Hydrolithon onkodes, a prolific global tropical reef species. Chemical micro-analysis of the coralline skeleton reveals that not only are the cell walls calcitised, but that cell spaces are typically filled with magnesite, rimmed by dolomite, or both. Mineralogy was confirmed by X-ray Diffraction. Thus there are at least three mineral phases present (magnesium calcite, dolomite and magnesite rather than one or two (magnesium calcite and brucite as previously thought. Our results are consistent with dolomite occurrences in coralline algae rich environments in fossil reefs of the last 60 million years. We reveal that the standard method of removing organic material prior to Xray Diffraction analysis can result in a decrease in the most obvious dolomite and magnesite diffraction patterns and this may explain why the abundant protodolomite and magnesite discovered in this study has not previously been recognized. This discovery of dolomite in living coralline algae extends the range of palaeo-environments for which biologically initiated dolomite can be considered a possible source of primary dolomite.

  14. First discovery of dolomite and magnesite in living coralline algae and its geobiological implications

    Science.gov (United States)

    Nash, M. C.; Troitzsch, U.; Opdyke, B. N.; Trafford, J. M.; Russell, B. D.; Kline, D. I.

    2011-11-01

    Dolomite is a magnesium-rich carbonate mineral abundant in fossil carbonate reef platforms but surprisingly rare in modern sedimentary environments, a conundrum known as the "Dolomite Problem". Marine sedimentary dolomite has been interpreted to form by an unconfirmed, post-depositional diagenetic process, despite minimal experimental success at replicating this. Here we show that dolomite, accompanied by magnesite, forms within living crustose coralline alga, Hydrolithon onkodes, a prolific global tropical reef species. Chemical micro-analysis of the coralline skeleton reveals that not only are the cell walls calcitised, but that cell spaces are typically filled with magnesite, rimmed by dolomite, or both. Mineralogy was confirmed by X-ray Diffraction. Thus there are at least three mineral phases present (magnesium calcite, dolomite and magnesite) rather than one or two (magnesium calcite and brucite) as previously thought. Our results are consistent with dolomite occurrences in coralline algae rich environments in fossil reefs of the last 60 million years. We reveal that the standard method of removing organic material prior to Xray Diffraction analysis can result in a decrease in the most obvious dolomite and magnesite diffraction patterns and this may explain why the abundant protodolomite and magnesite discovered in this study has not previously been recognized. This discovery of dolomite in living coralline algae extends the range of palaeo-environments for which biologically initiated dolomite can be considered a possible source of primary dolomite.

  15. Hydration Assessment of Athletes

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ KEY POINTS · Although there is no scientific consensus for 1 ) howbest to assess the hydration status of athletes, 2)what criteria to use as acceptable outcome measurements, or 3) the best time to apply practical assessment methods, there are methods that can be used toprovide athletes with useful feedback about their hydration status

  16. An Improved Clearing and Mounting Solution to Replace Chloral Hydrate in Microscopic Applications

    Directory of Open Access Journals (Sweden)

    Thomas S. Villani

    2013-05-01

    Full Text Available Premise of the study: This study presents Visikol™, a new proprietary formulation that can be used as an efficient replacement for chloral hydrate as a clearing agent for microscopic examination. In the United States, chloral hydrate is regulated and therefore difficult to acquire. Methods and Results: Fresh and dry samples of the following plants: ginger (Zingiber officinale, maté (Ilex paraguariensis, lime basil (Ocimum americanum, oregano (Origanum vulgare, and mouse-ear cress (Arabidopsis thaliana, were cleared using Visikol or chloral hydrate solution and compared using a light microscope. Conclusions: This new method can be used successfully to clear specimens, allowing identification of diagnostic characteristics for the identification of plant materials. Visikol is as effective as chloral hydrate in providing clarity and resolution of all tissues examined. Tissues become transparent, allowing observation of deeper layers of cells and making it effective in research, botanical and quality control, and for educational applications.

  17. Mineralogy of the Culebra Dolomite Member of the Rustler Formation

    Energy Technology Data Exchange (ETDEWEB)

    Sewards, T.; Williams, M.L.; Keil, K. (New Mexico Univ., Albuquerque, NM (USA))

    1991-03-01

    This report characterizes the mineralogy of the Culebra Member of the Rustler Formation based on studies of samples from cores of eight boreholes surrounding the WIPP repository. This investigation has three main goals: to obtain accurate modal compositions of all the samples selected; to investigate both the lateral and vertical variation of the mineralogy of the Culebra unit; and, to characterize water-bearing fracture surfaces in particular detail. The Culebra Dolomite member of the Rustler Formation is mineralogically and texturally heterogeneous, both vertically and horizontally. Although the predominant mineral is dolomite, important constituents of the formation are clay, quartz, gypsum, and calcite. Trace minerals include halite, phyllosilicates of metamorphic origin, feldspar, and pyrite. 24 refs., 90 figs., 27 tabs.

  18. Neutron activation analysis of multimetallic accumulation in dolomites

    Directory of Open Access Journals (Sweden)

    Zovko Emira

    2008-01-01

    Full Text Available The reason for exploring polymetallic ores, which are found in dolomite structures of the Veovača and Borovica zone near Vareš, lies in the fact that there is very little information about its chemical structure. The isolated concentrates that we analyzed from surface mines, have shown significant difference in quantity of trace elements. Deep probing of the whole area was not performed, but there are presumptions that there are roots of ore-rich dolomites in the areas of 30 - 40 km. The future concept of exploitation of these mines in the Vareš zone would probably require deeper probing. There are prospects for finding higher quality deposits with significant quantities of polymetallic components. By the method of neutron activation analysis the existence of mercury in amounts of about 0.4 % was confirmed. Because of the presence of mercury, these concentrates are not appropriate for pyrometallurgy, since it may result in environment contamination.

  19. Order–disorder–reorder process in thermally treated dolomite samples

    DEFF Research Database (Denmark)

    Zucchini, Azzurra; Comodi, Paola; Katerinopoulou, Anna;

    2012-01-01

    A combined powder and single-crystal X-ray diffraction analysis of dolomite [CaMg(CO3)2] heated to 1,200oC at 3 GPa was made to study the order–disorder–reorder process. The order/disorder transition is inferred to start below 1,100oC, and complete disorder is attained at approximately 1,200o...

  20. Energy efficiency opportunity guide in the lime industry

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    The lime industry processes limestone, an abundant inorganic mineral, for metallurgical, industrial and chemical, environmental, and construction applications. The energy the industry uses results in greenhouse gas emissions and the Canadian Lime Institute, in collaboration with Natural Resources Canada, sponsored the development of this guidebook which is intended to provide ideas for saving energy in the lime industry. This document is a practical source of information and can be used to develop self-audit and evaluation techniques to monitor energy usage. The report first provides an overview of the lime industry, then presents its energy costs. General energy efficiency methodologies are highlighted and, in conclusion, advice on improving energy efficiency in general and specifically for lime industry operations is given. This guidebook provides useful information for lime industry operators who are trying to improve the energy efficiency of their operations.

  1. Engineering Properties of Bentonite Stabilized with Lime and Phosphogypsum

    OpenAIRE

    Kumar Sujeet MR; Dutta Rakesh Kumar; Mohanty Bijayananda

    2014-01-01

    Engineering properties such as compaction, unconfined compressive strength, consistency limits, percentage swell, free swell index, the California bearing ratio and the consolidation of bentonite stabilized with lime and phosphogypsum are presented in this paper. The content of the lime and phosphogypsum varied from 0 to 10 %. The results reveal that the dry unit weight and optimum moisture content of bentonite + 8 % lime increased with the addition of 8 % phosphogypsum. The percentage of swe...

  2. Hydration rate of obsidian.

    Science.gov (United States)

    Friedman, I; Long, W

    1976-01-30

    The hydration rates of 12 obsidian samples of different chemical compositions were measured at temperatures from 95 degrees to 245 degrees C. An expression relating hydration rate to temperature was derived for each sample. The SiO(2) content and refractive index are related to the hydration rate, as are the CaO, MgO, and original water contents. With this information it is possible to calculate the hydration rate of a sample from its silica content, refractive index, or chemical index and a knowledge of the effective temperature at which the hydration occurred. The effective hydration temperature can be either measured or approximated from weather records. Rates have been calculated by both methods, and the results show that weather records can give a good approximation to the true EHT, particularly in tropical and subtropical climates. If one determines the EHT by any of the methods suggested, and also measures or knows the rate of hydration of the particular obsidian used, it should be possible to carry out absolute dating to +/- 10 percent of the true age over periods as short as several years and as long as millions of years.

  3. Fluid inclusion and isotopic evidence on dolomitization, Devonian of Western Canada

    Energy Technology Data Exchange (ETDEWEB)

    Aulstead, K.L.; Spencer, R.J.; Krouse, H.R. (Univ. of Calgary, Alberta (Canada))

    1988-05-01

    The Presqu'ile and Manetoe Facies are diagenetic features developed in Lower and Middle Devonian Formations of the Elk Point Basin (Presqu'ile) and the Mackenzie Shelf (Manetoe). Both facies contain coarsely crystalline dolomite and white sparry dolomite cement. Less extensive diagenetic phases, in order of paragenesis, include fluorite, anhydrite, barite, calcite, quartz, sphalerite and galena. Conditions of dolomitization are outlined from core and outcrop examination, thin section and cathodoluminescent petrography, fluid inclusion analyses, and C and O isotopic data. Fluid inclusion and stable isotope analyses from dolomite are combined to determine the isotopic composition of the dolomitizing fluids. Chemical analyses of fluid inclusion waters are compared with formation water analyses to derive a proposed origin for the diagenetic fluids. Dolomite formed from hot, high salinity fluids early in the diagenetic history of the basin. Limestone was dolomitized as a result of the same process that created white sparry dolomite cement in the Manetoe Facies. Remnants of the dolomitizing fluids are present as formation waters in some Devonian formations in Alberta. Subsequent invasion of meteoric waters produced more dilute diagenetic fluids which resulted in the precipitation of calcite and quartz cement in the Manetoe Facies. These fluids are present in fluid inclusions and are responsible for the low {sup 18}O content of the calcite cement. The temperatures of calcite and quartz formation differ as a function of burial depth within the Manetoe Facies during the Mesozoic and Cenozoic, while the temperature of formation for dolomite does not.

  4. Hydrothermal dolomites in SW Sardinia (Italy): evidence for a widespread late-Variscan fluid flow event

    Science.gov (United States)

    Boni, M.; Parente, G.; Bechstädt, T.; De Vivo, B.; Iannace, A.

    2000-03-01

    Epigenetic replacive and saddle dolomite, frequently forming zebra structures (Geodic dolomite), affected Cambrian limestones and early diagenetic dolomites across large areas of the Iglesiente-Sulcis mining district (SW Sardinia, Italy). The dolomite crops out in an area of more than 500 km 2 and reaches a thickness of up to 600 m (or even more). This rock represents one of the most extensive dolomites of epigenetic origin yet documented. Prior to dolomitization, the Cambrian carbonates underwent ductile deformation and greenschist facies metamorphism. The same is true for the overlying tectonic nappes. Fluid inclusion analysis combined with O- and Sr-isotope data indicate that the dolomitizing fluid can be categorized as a "basinal brine". The spread in homogenization temperatures shows a gradient with values decreasing from east to west. The higher temperatures (mean of around 100°C) have been measured in eastern parts of the Iglesiente area, whereas the lowermost temperatures (mean of about 85°C) have been found along the western coast of Iglesiente. This fluid certainly can neither have come directly from the low-grade metamorphic lithotypes undergoing dolomitization, nor from the low-temperature metamorphic rocks within the overlying nappes. It is assumed that a late-Variscan hydrothermal event, which coincided with extensional tectonics, set brine circulation into motion. Dolomitization may have occurred within circulation cells, which were driven by high heat flow. Fluids originated in the underlying rocks and circulated upward to affect the overlying Cambrian carbonates. An alternative model is that the dolomitization was caused by hydrothermal brines that originated within basinal areas of the Variscan orogenic pile circulating deep within the crust, and ascended in the External Zone (Iglesiente-Sulcis). Whatever the origin, these reducing saline fluids, which carried radiogenic Sr, dolomitized a large volume of Early Paleozoic rocks. The many

  5. Hydrate morphology: Physical properties of sands with patchy hydrate saturation

    Science.gov (United States)

    Dai, S.; Santamarina, J.C.; Waite, William F.; Kneafsey, T.J.

    2012-01-01

    The physical properties of gas hydrate-bearing sediments depend on the volume fraction and spatial distribution of the hydrate phase. The host sediment grain size and the state of effective stress determine the hydrate morphology in sediments; this information can be used to significantly constrain estimates of the physical properties of hydrate-bearing sediments, including the coarse-grained sands subjected to high effective stress that are of interest as potential energy resources. Reported data and physical analyses suggest hydrate-bearing sands contain a heterogeneous, patchy hydrate distribution, whereby zones with 100% pore-space hydrate saturation are embedded in hydrate-free sand. Accounting for patchy rather than homogeneous hydrate distribution yields more tightly constrained estimates of physical properties in hydrate-bearing sands and captures observed physical-property dependencies on hydrate saturation. For example, numerical modeling results of sands with patchy saturation agree with experimental observation, showing a transition in stiffness starting near the series bound at low hydrate saturations but moving toward the parallel bound at high hydrate saturations. The hydrate-patch size itself impacts the physical properties of hydrate-bearing sediments; for example, at constant hydrate saturation, we find that conductivity (electrical, hydraulic and thermal) increases as the number of hydrate-saturated patches increases. This increase reflects the larger number of conductive flow paths that exist in specimens with many small hydrate-saturated patches in comparison to specimens in which a few large hydrate saturated patches can block flow over a significant cross-section of the specimen.

  6. Wet hydrate dissolution plant

    OpenAIRE

    Stanković Mirjana S.; Kovačević Branimir T.; Pezo Lato L.

    2003-01-01

    The IGPC Engineering Department designed basic projects for a wet hydrate dissolution plant, using technology developed in the IGPC laboratories. Several projects were completed: technological, machine, electrical, automation. On the basis of these projects, a production plant with capacity of 50,000 t/y was manufactured, at "Zeolite Mira", Mira (VE), Italy, in 1997, for increasing detergent zeolite production from 50,000 to 100,000 t/y. Several goals were realized by designing a wet hydrate ...

  7. LIMES Large Infrastructure in Mathematics - Enhanced Services

    CERN Document Server

    Fachinformationszentrum Energie, Physik, Mathematik. Karlsruhe

    The Large Infrastructure in Mathematics - Enhanced Services (LIMES) Project is a RTD project within the Fifth (EC) Framework Programme - Horizontal Programme "Improving human research potential and the socio-economic knowledge base", Access to Resear The objective of this project is to upgrade the existing database Zentralblatt-MATH into a European based world class database for mathematics (pure and applied) by a process of technical improvement and wide Europeanisation, improving the present distribuited system. The goal is to make Zentralblatt MATH a world reference database, offering full coverage of the mathematics literature worldwide ncluding bibliographic data, peer reviews and/or abstracts, indexing, classification and search,

  8. An Aerobic Digestion of Lime Sludge.

    Science.gov (United States)

    1982-07-01

    AD-AL1B 502 AllMy MEDICAL BIOENGINEERING RESEARCH AND DEVELOPMENT -- ETC F/6 13/2 ANAEROBIC DIGESTION OF LIME SLUDGE.U) JUL 82 EA KBYLINSKI, B A BELL...Applied for Digesters 1 and 3, Run 1 9262- 9313 .................................... 55 32. Volatile Solids Destroyed vs. Volatile Solids Applied for...CONCENTRATIONS Feed Effluent NH-N NH -N Reactor Run Julian Date mgfL mg/L 1 1 9261- 9313 100 203 1 1 9314-0008 58 243 2 1 9261-0008 72 147 3 1 9261

  9. SELECTED CHARACTERISTICS OF LIMESTONE AND DOLOMITE RESERVOIRS IN THE UNITED STATES.

    Science.gov (United States)

    Schmoker, James W.; Krystinik, Katherine B.; Halley, Robert B.

    1985-01-01

    Limestone reservoirs are more numerous in the United States than dolomite reservoirs (by a ratio of about 3 to 1) because limestones are more abundant than dolomite. However, in the eight states that account for over 90% of United States carbonate reservoirs, there is a statistical tendency for carbonate reservoirs to occur preferentially in dolomites. Dolomite reservoirs, on the average, are larger and deeper than those of limestone, yet they often have lower matrix porosities and permeabilities. This line of investigation offers supplemental evidence that dolomitization tends to improve the reservoir properties of a given formation, and that effective fracture systems at reservoir depths are more likely to occur in dolomites than in limestones. Refs.

  10. Thorough investigation of the oxygen heterocyclic fraction of lime (Citrus aurantifolia (Christm.) Swingle) juice.

    Science.gov (United States)

    Costa, Rosaria; Russo, Marina; De Grazia, Selenia; Grasso, Elisa; Dugo, Paola; Mondello, Luigi

    2014-04-01

    Reversed-phase-HPLC analysis by means of superficially porous silica particle columns (fused-core) was applied to the investigation of flavonoids, coumarins, and psoralens in lime juice samples. Hesperidin (367.0 ± 16.0 ppm) and eriocitrin (148.0 ± 7.9 ppm) were the most abundant flavonoids. Fifteen coumarins and furocoumarins were determined, including bergamottin (29.6 ± 1.1 ppm), 5-geranyloxy-7-methoxycoumarin (16.5 ± 0.6 ppm), and oxypeucedanin hydrate (9.9 ± 0.5 ppm) as predominant compounds. These molecules are today well known for their beneficial effects on human health. As a consequence, the present study, beyond investigating for the first time the chemical composition of lime juice, highlights also its health-promoting qualities, due to its content of flavonoids and coumarins. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Analysis of Engineering Properties of Black Cotton Soil & Stabilization Using By Lime.

    Directory of Open Access Journals (Sweden)

    Kavish S. Mehta

    2014-05-01

    Full Text Available With the increasing of population and the reduction of available land, more and more construction of buildings and other civil engineering structures have to be carried out on weak or soft soil. Owing to such soil of poor shear strength and high swelling & shrinkage, a great diversity of ground improvement techniques such as soil stabilization and reinforcement are employed to improve mechanical behavior of soil, thereby enhancing the reliability of construction. Black cotton soil is one of the major soil deposits of India. They exhibit high swelling and shrinking when exposed to changes in moisture content and hence have been found to be most troublesome from engineering considerations. Stabilization occurs when lime is added to black cotton soil and a pozzolanic reaction takes place. The hydrated lime reacts with the clay particles and permanently transforms them into a strong cementations matrix. Black cotton soil showing low to medium swelling potential from Rajkot Gujarat was used for determining the basic properties of the soil. Changes in various soil properties such as Liquid limit, Plastic Limit, Maximum Dry Density, Optimum Moisture Content, and California Bearing Ratio were studied. Keywords–

  12. 77 FR 45715 - Application of Key Lime Air Corporation for Commuter Authority

    Science.gov (United States)

    2012-08-01

    ...] Application of Key Lime Air Corporation for Commuter Authority AGENCY: Department of Transportation. ACTION... Lime Air Corporation fit, willing, and able, and awarding it a Commuter Air Carrier...

  13. Surface chemistry allows for abiotic precipitation of dolomite at low temperature

    OpenAIRE

    Roberts, Jennifer A.; Kenward, Paul A.; Fowle, David A.; Goldstein, Robert H.; Luis A. González; Moore, David S.

    2013-01-01

    Abundant in the geologic record, but scarce in modern environments below 50 °C, the mineral dolomite is used to interpret ancient fluid chemistry, paleotemperature, and is a major hydrocarbon reservoir rock. Because laboratory synthesis of abiotic dolomite had been unsuccessful, chemical mechanisms for precipitation are poorly constrained, and limit interpretations of its occurrence. Here we report the abiotic synthesis of dolomite at 25 °C, and demonstrate that carboxylated surfaces on organ...

  14. Dolomitized cells within chert of the Permian Assistência Formation, Paraná Basin, Brazil

    Science.gov (United States)

    Calça, Cléber P.; Fairchild, Thomas R.; Cavalazzi, Barbara; Hachiro, Jorge; Petri, Setembrino; Huila, Manuel Fernando Gonzalez; Toma, Henrique E.; Araki, Koiti

    2016-04-01

    Dolomitic microscopic structures in the form of microspheres, "horseshoe- shaped" objects, and thin botryoidal crusts found within microfossiliferous chert within stromatolites of the Evaporite Bed (EB) of the Permian Assistência Formation, Irati Subgroup, Paraná Basin, Brazil, have been investigated by means of optical microscopy, X-ray fluorescence, scanning electron microscopy, Raman spectrometry and energy-dispersive X-ray spectrometry. The microspheres were identified as dolomitized coccoidal cyanobacteria based on similarity in size, spheroidal and paired hemispheroidal morphologies and colonial habit to co-occurring silicified organic-walled cyanobacteria embedded within the same microfabric and rock samples. The co-occurrence of dolomite, pyrite framboids, and abundant dispersed carbonaceous material and silicified cells is consistent with a hypersaline depositional environment with abundant cyanobacterial mats and elevated Mg2 +/Ca2 + ratios and reducing conditions with active anoxic microbial processes near the water-(bio)sediment interface. The abundance of extracellular polymeric substances facilitated anoxic microbial processes (sulfate reduction), providing essential conditions for possible primary microbially induced dolomitization. In most of the dolomitized cells dolomite occurs only as an external layer; in fully dolomitized cells magnesium is richest in the outermost layer. Presumably, the dolomitization process was favored by the presence of anoxic microbial degraders and negatively charged functional groups at the surface of the cyanobacterial cells. Botryoidal dolomite rims of silica-filled fenestrae formed by a similar process and inherited the botryoidal morphology of the cell as originally lining the fenestrae. Silicification interrupted the dolomitization of the largely organic biosediment, mostly by permineralization, but locally by substitution, thereby preserving not only dolomitic microspheres, but also huge numbers of structurally

  15. Antibacterial activity of garlic and lime on isolates of extracted ...

    African Journals Online (AJOL)

    USER

    2010-05-24

    May 24, 2010 ... essential ingredient in the preparation of most herbal concortions. It is used ... The antimicrobial activity of the volatile oils of tangerine fruit peel ... (Zingber officinale Roscoe) and lime on Staphylococcus aureus, Bacillus sp. ..... (Zingiber officinale Roscoe) and lime (Citrus aurantifolia Linn). Afr. J. Biotechnol.

  16. Efficacy and phytotoicity of lime sulphur in organic apple production

    NARCIS (Netherlands)

    Holb, I.J.; Jong, de P.F.; Heijne, B.

    2003-01-01

    Curative and preventive efficacy and phytotoxicity of lime sulphur spray schedules, based on a warning system, were evaluated in the Netherlands during two growing seasons under field conditions. In most cases, lime sulphur treatments applied either curatively or preventively resulted in significant

  17. Effects of lime juice on malaria parasite clearance.

    Science.gov (United States)

    Adegoke, S A; Oyelami, O A; Olatunya, O S; Adeyemi, L A

    2011-10-01

    One hundred and twenty children with acute uncomplicated malaria who were managed at the children's outpatient department of the Wesley Guild Hospital, Ilesa (a unit of Obafemi Awolowo University Teaching Hospitals' Complex, Ile-Ife, Osun state, Nigeria) were recruited into the study to determine the effects of lime juice on malaria parasite clearance. These children were randomized into treatment with World Health Organization recommended antimalarials (artemisinin combination therapy, ACT) either alone or with lime juice. Nine of them were lost to follow-up, four were in the group that were managed with ACT and lime, and five in the group that were managed on ACT alone. The average (SD) time to achieve >75% reduction in parasite load was significantly lower in patients on ACT and lime; 30.5 ± 2.4 h against 38.6 ± 3.3 h for those on ACT alone (p lime juice achieved complete parasite clearance by 72 h of therapy (p = 0.007), ten (18.2%) patients without lime had early treatment failure (p = 0.003). There were no side effects with the use of lime juice. It may therefore be inferred, from this preliminary work, that lime juice when used with the appropriate antimalarial may enhance malaria parasite clearance especially in those with uncomplicated malaria.

  18. Investigation of Copper Sorption by Sugar Beet Processing Lime Waste

    Science.gov (United States)

    In the western United States, sugar beet processing for sugar recovery generates a lime-based waste product (~250,000 Mg yr-1) that has little liming value in the region’s calcareous soils. This area has recently experienced an increase in dairy production, with dairi...

  19. 76 FR 82295 - Central Power & Lime LLC; Notice of Filing

    Science.gov (United States)

    2011-12-30

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Central Power & Lime LLC; Notice of Filing December 23, 2011. Take notice that on December 22, 2011, Central Power & Lime LLC, pursuant to sections 18 CFR 292.205(c) and...

  20. Investigation of Copper Sorption by Sugar Beet Processing Lime Waste

    Science.gov (United States)

    In the western United States, sugar beet processing for sugar recovery generates a lime-based waste product (~250,000 Mg yr-1) that has little liming value in the region’s calcareous soils. This area has recently experienced an increase in dairy production, with dairi...

  1. Engineering Properties of Bentonite Stabilized with Lime and Phosphogypsum

    Directory of Open Access Journals (Sweden)

    Kumar Sujeet

    2014-12-01

    Full Text Available Engineering properties such as compaction, unconfined compressive strength, consistency limits, percentage swell, free swell index, the California bearing ratio and the consolidation of bentonite stabilized with lime and phosphogypsum are presented in this paper. The content of the lime and phosphogypsum varied from 0 to 10 %. The results reveal that the dry unit weight and optimum moisture content of bentonite + 8 % lime increased with the addition of 8 % phosphogypsum. The percentage of swell increased and the free swell index decreased with the addition of 8 % phosphogypsum to the bentonite + 8 % lime mix. The unconfined compressive strength of the bentonite + 8 % lime increased with the addition of 8 % phosphogypsum as well as an increase in the curing period up to 14 days. The liquid limit and plastic limit of the bentonite + 8 % lime increased, whereas the plasticity index remained constant with the addition of 8 % phosphogypsum. The California bearing ratio, modulus of subgrade reaction, and secant modulus increased for the bentonite stabilized with lime and phosphogypsum. The coefficient of the consolidation of the bentonite increased with the addition of 8 % lime and no change with the addition of 8 % phosphogypsum.

  2. Engineering Properties of Bentonite Stabilized with Lime and Phosphogypsum

    Science.gov (United States)

    Kumar, Sujeet; Dutta, Rakesh Kumar; Mohanty, Bijayananda

    2014-12-01

    Engineering properties such as compaction, unconfined compressive strength, consistency limits, percentage swell, free swell index, the California bearing ratio and the consolidation of bentonite stabilized with lime and phosphogypsum are presented in this paper. The content of the lime and phosphogypsum varied from 0 to 10 %. The results reveal that the dry unit weight and optimum moisture content of bentonite + 8 % lime increased with the addition of 8 % phosphogypsum. The percentage of swell increased and the free swell index decreased with the addition of 8 % phosphogypsum to the bentonite + 8 % lime mix. The unconfined compressive strength of the bentonite + 8 % lime increased with the addition of 8 % phosphogypsum as well as an increase in the curing period up to 14 days. The liquid limit and plastic limit of the bentonite + 8 % lime increased, whereas the plasticity index remained constant with the addition of 8 % phosphogypsum. The California bearing ratio, modulus of subgrade reaction, and secant modulus increased for the bentonite stabilized with lime and phosphogypsum. The coefficient of the consolidation of the bentonite increased with the addition of 8 % lime and no change with the addition of 8 % phosphogypsum.

  3. Microtextural Characteristics and Origin of Dolomites in the Tepearasi Formation, SW of Beysehir-Konya, Turkey

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The Tepearasi Formation of the autochthonous Geyikdagi Group in the Central Tauride Belt, SE of Beysehir, is Dogger in age and consists dominantly of massive limestones and greyish dolomites occurring within the middle to upper sections. The total thickness of the dolomitic levels ranges from 100–300 m and laterally extends 500–700 m. Three types of dolomite were distinguished through petrographic analyses: homogeneous, mottled (saddle-crystalline) and joint-filling dolomite, which were interpreted to have formed in two different stages, early diagenetic and late diagenetic. The homogeneous dolomite of the early diagenetic stage is light-coloured and monotonous-textured and shows the form of a dolosparite mosaic. The mottled dolomite formed in the late diagenetic stage is light- to dark-coloured and coarsely granular idiomorphic. The other type of late diagenetic dolomite, described as the joint-filling type, presents a crystal growth pattern from the joint walls towards the centre of the joint space. It is associated with coarse calcite crystals as well as primary dolomite crystal clasts which were formed in the early diagenetic stage. In addition to these characteristics, cataclastic texture indicating the influence of tectonism is also observed. Microtexture-oriented scanning electron microscopy (SEM) studies indicate that mottled dolomites show zonal structures and contain secondary dissolution vugs. SEM studies also revealed the existence of some remains (calcite, clay etc.) in joint-filling dolomites. Analyses by energy dispersive spectrometry (EDS) indicate the existence of clay minerals (likely to be illite) in the pores of dolomite. Isotope studies conducted to shed light onto the origin of the dolomites of the Tepearasi Formation yielded the results of ?18O= –2.48 to – 3.87‰ and ?13C=0.93 to 1.12‰ for the early diagenetic homogeneous dolomites. Mottled and joint-filling type dolomites of the late diagenetic stage, on the other hand, gave the

  4. Relationship between karstification and burial dolomitization in Permian platform carbonates (Lower Khuff - Oman)

    Science.gov (United States)

    Beckert, Julia; Vandeginste, Veerle; John, Cédric M.

    2016-08-01

    Large breccia fabrics associated with karst constitute an important structure in massive limestone successions. The dimensions and shapes of breccia structures are controlled by the initial fracture pattern of the limestone and preferential pathways of the karstifying fluids, but subsequently breccia fabrics can also govern the migration of later fluids. Therefore, breccias are highly relevant features to capture for reservoir characterisation. Outcrop analogues for Lower Khuff units in the Middle East present in the Central Oman Mountains reveal brecciated fabrics up to 10s of metres in diameter. These brecciated units are closely associated with dolomite bodies of late diagenetic origin. Based on an integrated set of data, the breccias are interpreted as collapsed karst cavities either formed by meteoric or hypogenic fluids. The exact origin of the fluids could not be constrained due to an overprint by later dolomitizing fluids. Based on the composition of the clasts and matrix in the breccias, two dolomitization events are interpreted to have affected the succession, one prior to (early diagenetic [ED] dolomite) and one after brecciation (late diagenetic [DT2] dolomite). Dolomite of shallow burial origin (ED dolomite) was only observed as clasts within breccia and is much more frequent than late diagenetic (medium to deep burial) dolomite clasts. Thus, the timing of the brecciation and collapse is assumed to postdate shallow burial early diagenetic dolomitization. Late diagenetic replacive dolomite (DT2 dolomite) forms 90% of the matrix in the breccia fabrics with the exception of a small area that was not affected by dolomitization, but is rarely present as clasts. Stable isotope measurements [δ18O: - 2.5‰ to - 6‰ VPDB and δ13C: 2.9‰ to 4.8‰ VPDB] suggest a burial origin for the late diagenetic dolomite potentially with the participation of hydrothermal fluids. The dolomitized matrix indicates a migration of late dolomitizing fluids subsequent to or

  5. High salinity facilitates dolomite precipitation mediated by Haloferax volcanii DS52

    Science.gov (United States)

    Qiu, Xuan; Wang, Hongmei; Yao, Yanchen; Duan, Yong

    2017-08-01

    Although most modern dolomites occur in hypersaline environments, the effects of elevated salinity on the microbial mediation of dolomite precipitation have not been fully evaluated. Here we report results of dolomite precipitation in association with a batch culture of Haloferax volcanii DS52, a halophilic archaeon, under various salinities (from 120‰ to 360‰) and the impact of salinity on microbe-mediated dolomite formation. The mineral phases, morphology and atomic arrangement of the precipitates were analyzed by XRD, SEM and TEM, respectively. The amount of amino acids on the archaeal cell surface was quantified by HPLC/MS. The XRD analysis indicated that disordered dolomite formed successfully with the facilitation of cells harvested from cultures with relatively high salinities (200‰ and 280‰) but was not observed in association with cells harvested from cultures with lower salinity (120‰) or the lysates of cells harvested from extremely high salinity (360‰). The TEM analysis demonstrated that the crystals from cultures with a salinity of 200‰ closely matched that of dolomite. Importantly, we found that more carboxyl groups were presented on the cell surface under high salinity conditions to resist the high osmotic pressure, which may result in the subsequent promotion of dolomite formation. Our finding suggests a link between variations in the hydro-chemical conditions and the formation of dolomite via microbial metabolic activity and enhances our understanding about the mechanism of microbially mediated dolomite formation under high salinity conditions.

  6. Preparation and Characterization of Malaysian Dolomites as a Tar Cracking Catalyst in Biomass Gasification Process

    Directory of Open Access Journals (Sweden)

    M. A. A. Mohammed

    2013-01-01

    Full Text Available Three types of local Malaysian dolomites were characterized to investigate their suitability for use as tar-cracking catalysts in the biomass gasification process. The dolomites were calcined to examine the effect of the calcination process on dolomite’s catalytic activity and properties. The modifications undergone by dolomites consequent to thermal treatment were investigated using various analytical methods. Thermogravimetric and differential thermal analyses indicated that the dolomites underwent two stages of decomposition during the calcination process. The X-ray diffraction and Fourier-transform infrared spectra analyses showed that thermal treatment of dolomite played a significant role in the disappearance of the CaMg(CO32 phase, producing the MgO-CaO form of dolomite. The scanning electron microscopy microphotographs of dolomite indicated that the morphological properties were profoundly affected by the calcination process, which led to the formation of a highly porous surface with small spherical particles. In addition, the calcination of dolomite led to the elimination of carbon dioxide and increases in the values of the specific surface area and average pore diameter, as indicated by surface area analysis. The results showed that calcined Malaysian dolomites have great potential to be applied as tar-cracking catalysts in the biomass gasification process based on their favorable physical properties.

  7. Root distribution of rootstocks for 'Tahiti' lime

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    Neves Carmen Silvia Vieira Janeiro

    2004-01-01

    Full Text Available Field studies on citrus roots are important for genetic selection of cultivars and for management practices such as localized irrigation and fertilization. To characterize root systems of six rootstocks, taking into consideration chemical and physical characteristics of a clayey Typic Hapludox of the Northern State of Paraná, this study was performed having as scion the 'IAC-5 Tahiti' lime [Citrus latifolia (Yu. Tanaka]. The rootstocks 'Rangpur' lime (C. limonia Osbeck, 'Africa Rough' lemon (C. jambhiri Lush., 'Sunki' mandarin [C. sunki (Hayata hort. ex Tan.], Poncirus trifoliata (L. Raf., 'C13' citrange [C. sinensis (L. Osb. x P. trifoliata (L. Raf] and 'Catânia 2' Volkamer lemon (C. volkameriana Ten. & Pasq. were used applying the trench profile method and the SIARCS® 3.0 software to determine root distribution. 'C-13' citrange had the largest root system. 'Volkamer' lemon and 'Africa Rough' lemon presented the smallest amount of roots. The effective depth for 80 % of roots was 31-53 cm in rows and 67-68 cm in inter-rows. The effective distance of 80 % of roots measured from the tree trunk exceeded the tree canopy for P. trifoliata, 'Sunki' mandarin, and 'Volkamer' and 'Africa Rough' lemons.

  8. Oxidative lime pretreatment of Dacotah switchgrass.

    Science.gov (United States)

    Falls, Matthew; Sierra-Ramirez, Rocio; Holtzapple, Mark T

    2011-09-01

    Oxidative lime pretreatment increases the enzymatic digestibility of lignocellulosic biomass primarily by removing lignin. In this study, recommended pretreatment conditions (reaction temperature, oxygen pressure, lime loading, and time) were determined for Dacotah switchgrass. Glucan and xylan overall hydrolysis yields (72 h, 15 FPU/g raw glucan) were measured for 105 different reaction conditions involving three different reactor configurations (very short term, short term, and long term). The short-term reactor was the most productive. At the recommended pretreatment condition (120 °C, 6.89 bar O(2), 240 min), it achieved an overall glucan hydrolysis yield of 85.2 g glucan hydrolyzed/100 g raw glucan and an overall xylan yield of 50.1 g xylan hydrolyzed/100 g raw xylan. At this condition, glucan oligomers (1.80 g glucan recovered/100 g glucan in raw biomass) and xylan oligomers (25.20 g xylan recovered/100 g xylan in raw biomass) were recovered from the pretreatment liquor, which compensate for low pretreatment yields.

  9. Effect of SO2 Dry Deposition on Porous Dolomitic Limestones

    Science.gov (United States)

    Olaru, Mihaela; Aflori, Magdalena; Simionescu, Bogdana; Doroftei, Florica; Stratulat, Lacramioara

    2010-01-01

    The present study is concerned with the assessment of the relative resistance of a monumental dolomitic limestone (Laspra – Spain) used as building material in stone monuments and submitted to artificial ageing by SO2 dry deposition in the presence of humidity. To investigate the protection efficiency of different polymeric coatings, three commercially available siloxane-based oligomers (Lotexan-N, Silres BS 290 and Tegosivin HL 100) and a newly synthesized hybrid nanocomposite with silsesquioxane units (TMSPMA) were used. A comparative assessment of the data obtained in this study underlines that a better limestone protection was obtained when treated with the hybrid nanocomposite with silsesquioxane units.

  10. Effect of SO2 Dry Deposition on Porous Dolomitic Limestones

    Directory of Open Access Journals (Sweden)

    Florica Doroftei

    2010-01-01

    Full Text Available The present study is concerned with the assessment of the relative resistance of a monumental dolomitic limestone (Laspra – Spain used as building material in stone monuments and submitted to artificial ageing by SO2 dry deposition in the presence of humidity. To investigate the protection efficiency of different polymeric coatings, three commercially available siloxane-based oligomers (Lotexan-N, Silres BS 290 and Tegosivin HL 100 and a newly synthesized hybrid nanocomposite with silsesquioxane units (TMSPMA were used. A comparative assessment of the data obtained in this study underlines that a better limestone protection was obtained when treated with the hybrid nanocomposite with silsesquioxane units.

  11. Modern marine dolomite cement in a north Jamaican fringing reef

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, J.T.; Land, L.S.; Miser, D.E.

    1987-06-01

    Minor quantities of ordered dolomite (..delta../sup 18/O = +2.0 per thousand PDB; composition = Ca/sub 1.22/Mg/sub 0.78/ (CO/sub 3/)/sub 2/) have formed from near-normal seawater in a subtidal hardground as part of a modern fringing coral reef. Crystals 5 ..mu..m in diameter precipitated within the past 1.8 ka in the form of syntaxial fringes on Mg-calcite marine cements and skeletal allochems. The crystals have a fine modulated microstructure and c reflections, both apparently formed during crystal growth

  12. Using in situ REE analysis to study the origin and diagenesis of dolomite of Lower Paleozoic, Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    WANG XiaoLin; JIN ZhiJun; HU WenXuan; ZHANG JunTao; QIAN YiXiong; ZHU JingQuan; LI Qing

    2009-01-01

    In situ REE concentrations of various dolomites from Tarim Basin were obtained by LA-ICP-MS analysis, and the data were normalized to standard seawater (Seawater Normalized=SWN). Most of the samples have a ΣREE range of less than 20 ppm. All samples show similar REE distributions with heavy REE depletion, and positive Ce anomaly, which indicates that they have the same dolomitization fluids (seawater). According to the origin and diagenetic process of dolomite, two types of dolomite are de-termined and described as follows: 1) syndepositional dolomite, with the highest REE concentrations (more than 20 ppm), the cores of which are more enriched in REE compared with their cortexes, indicating that they underwent the dolomitization of calcareous sediments by hypersaline and subsequent diagenesis decreased the REE content of the cortex because of the low REE concentration of the diagenetic fluids; 2) diagenetic dolomite, which can be subdivided into four groups. (1) burial dolomite which has higher REE concentrations than limestone, but lower than syndepositional dolomite. This shows that pore fluids with high salinity dolomitized the pre-existing limestone; (2) void filling dolomite which has the similar REE patterns with the matrix dolomite. In addition, the Eu anomaly is not obvious, suggesting that the dolomitization fluids originated from the diagenetic fluids; (3) recrystallized dolomite, whose REE concentration was obviously decreased, indicating that the REE concentration was decreased during the recrystallization processes; and (4) hydrothermal altered void-filling dolomite, which has the lowest REE concentration, but obvious positive Eu anomaly, reflecting its hydrothermal activity related origin. Thus, the diverse REE signatures, which were recorded in different dolomites, retain the information of their formation conditions and subsequent diagenetic processes. In situ REE analysis of dolomite is an effective probe into the origin and diagenetic process of

  13. Using in situ REE analysis to study the origin and diagenesis of dolomite of Lower Paleozoic,Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In situ REE concentrations of various dolomites from Tarim Basin were obtained by LA-ICP-MS analysis,and the data were normalized to standard seawater(Seawater Normalized=SWN).Most of the samples have a ΣREE range of less than 20 ppm.All samples show similar REESWN distributions with heavy REE depletion,and positive Ce anomaly,which indicates that they have the same dolomitization fluids(seawater).According to the origin and diagenetic process of dolomite,two types of dolomite are determined and described as follows:1) syndepositional dolomite,with the highest REE concentrations(more than 20 ppm),the cores of which are more enriched in REE compared with their cortexes,indicating that they underwent the dolomitization of calcareous sediments by hypersaline and subsequent diagenesis decreased the REE content of the cortex because of the low REE concentration of the diagenetic fluids;2) diagenetic dolomite,which can be subdivided into four groups.(1) burial dolomite which has higher REE concentrations than limestone,but lower than syndepositional dolomite.This shows that pore fluids with high salinity dolomitized the pre-existing limestone;(2) void filling dolomite which has the similar REE patterns with the matrix dolomite.In addition,the Eu anomaly is not obvious,suggesting that the dolomitization fluids originated from the diagenetic fluids;(3) recrystallized dolomite,whose REE concentration was obviously decreased,indicating that the REE concentration was decreased during the recrystallization processes;and(4) hydrothermal altered void-filling dolomite,which has the lowest REE concentration,but obvious positive Eu anomaly,reflecting its hydrothermal activity related origin.Thus,the diverse REE signatures,which were recorded in different dolomites,retain the information of their formation conditions and subsequent diagenetic processes.In situ REE analysis of dolomite is an effective probe into the origin and diagenetic process of dolomite.

  14. Elastic and Transport Properties of Steam-Cured Pozzolanic-Lime Rock Composites Upon CO2 Injection

    Science.gov (United States)

    Emery, Dan; Vanorio, Tiziana

    2016-04-01

    Understanding the effect of pozzolanic ash-lime reactions on the rock physics properties of the resulting rock microstructure is important for monitoring unrest conditions in volcanic-hydrothermal systems as well as for devising concrete with enhanced performance. By mixing pozzolana ash with lime, the ancient Romans unwittingly incorporated these reactions in the production of their famous concrete. Recently, it has been discovered that a fiber-reinforced, concrete-like rock is forming naturally at depth of 1.5 km within the Campi Flegrei volcanic-hydrothermal systems due to upwelling lime-rich fluids permeating a pozzolana rich layer. This study aims to investigate possible physico-chemical conditions contributing to both enhance and undermine the properties of the subsurface rocks of volcanic-hydrothermal systems and, in turn, build upon those processes that the ancient Romans exploited to create their famous concrete. We prepared samples by mixing the pozzolana volcanic ash, slaked lime, aggregates of Neapolitan Yellow tuff, and seawater from Campi Flegrei in the same ratios as the ancient Romans. To mimic the conditions of the caldera, we used alkaline water from a well in the Campi Flegrei region rich in sulfate, bicarbonate, calcium, potassium, and magnesium ions. Yet, the samples were cured for 28 days in steam-rich environment to favor hydration and hence, enhancing the stability of calcium- alumino-silicate hydrates and setting strength of the rock samples. We measured baseline properties of porosity, permeability, P-wave velocity, and S-wave velocity of the samples as well as imaged the fibrous microstructure. P and S-wave velocities were used to derive bulk, shear, and Young's moduli. Subsequently, samples were injected with an aqueous carbon dioxide, CO2 (aq), solution and the changes in their microstructure and physical properties measured. Exposure of the concrete-like rock samples to CO2 -rich fluid lowers pH below 12.5, thus affecting the stability

  15. Dolomitization and sedimentary cyclicity of the Ordovician, Silurian, and Devonian rocks in South Estonia

    Directory of Open Access Journals (Sweden)

    Kallaste, Toivo

    2006-03-01

    Full Text Available The distribution and composition of dolomitized rocks and stoichiometry of dolomite in southern Estonia in the Ordovician, Silurian, and Devonian were studied on the background of the facies, sedimentary cyclicity (nine shallowing-up cycles, and evolution of the palaeobasins. The composition of rocks and lattice parameters of dolomite were investigated using the X-ray diffraction, X-ray fluorescence, titration and gravimetric analyses, and porosity measurements. The formation of dolostones is directly determined by the cyclic evolution of palaeobasins. Dolomitized rocks belong to the shallow-water inner shelf or tidal/lagoonal facies belt of regressive phases of sedimentary cycles. Sediments of the deep shelf/transitional environment and transgressive phases are not dolomitized. The most stoichiometric is secondary replacive dolomite of Silurian and upper Ordovician dolostones, formed during the early diagenesis of normal-marine (saline shallow-shelf calcitic sediments. The content of insoluble residue does not affect the stoichiometry. The changes in lattice parameters are induced by the Ca/Mg ratio in the dolomite lattice. The dolomite of the dolostones contacting limestone or containing calcite has an expanded lattice. The primary (syngenetic dolostone of the lagoonal or tidal flat belt has also an expanded lattice. No dolomitizing effect of the waters of the Devonian palaeobasin on the underlying rocks was revealed. The whole data set of the studied dolostones is consistent with the marine water environment in the palaeobasin at the corresponding time and shows no sign of the inflow of external fluids. It suggests that the microbial model of dolomite formation may characterize the Ordovician, Silurian, and Devonian in southern Estonia. The occurrence of dolostones between undolomitized rocks limits the time of dolomitization to the early diagenetic stage.

  16. Dolomite flotation of high magnesium phosphate ores using fatty acid soap collectors

    Science.gov (United States)

    Gu, Zhengxing

    The separation of dolomite from apatite has been recognized as one of the most difficult subjects in mineral processing due to the similarities in their physiochemical properties. In this study, selective surfactants were used with a fatty acid soap collector to improve the flotation performance of separating dolomite from high magnesium phosphate ores. Three surfactants, diethyl phthalate (DP), Tween-80 (TW) and derivative of sulfonate salt (DSS1) were used. Hallimond cell flotation was conducted using pure dolomite sample to determine the effects of various factors including dosages, particle size, Ca2+ ions and slimes on the dolomite flotation recovery. The results showed that the surfactants can significantly improve dolomite flotation performance by increasing collecting ability and tolerating the effect of calcium ions and slime contents. The stirrer-tank cell batch flotation tests were carried out using two natural high magnesium phosphate ore samples containing 3.3% and 1.5% MgO. The test results showed that the surfactant DP could improve dolomite flotation at low dosages, and DSS1 could enhance the separation of dolomite from phosphate by improving both collecting ability and flotation selectivity. When 10% of DSS1 was used with the fatty acid soap as collector, at least 10% more dolomite can be removed with less P2O5 loss. The effectiveness of the surfactant DSS1 in enhancing dolomite flotation was further demonstrated in modified packed column flotation with natural dolomitic phosphate ore sample. The addition of the surfactant DSS1 into fatty acid soap collector could improve its frothability and froth stability, and reduce the bubble size. It has been found that the dolomite flotation performance has a close relationship with the frothability and froth stability of the collector.

  17. PART II. HYDRATED CEMENTS

    Directory of Open Access Journals (Sweden)

    Milan Drabik

    2014-09-01

    Full Text Available Essential focus of the study has been to acquire thermoanalytical events, incl. enthalpies of decompositions - ΔH, of technological materials based on two types of Portland cements. The values of thermoanalytical events and also ΔH of probes of technological compositions, if related with the data of a choice of minerals of calcium-silicate-sulfate-aluminate hydrates, served as a valued input for the assessment of phases present and phase changes due to the topical hydraulic processes. The results indicate mainly the effects of "standard humidity" or "wet storage" of the entire hydration/hydraulic treatment, but also the presence of cement residues alongside calcium-silicate-sulfate-aluminate hydrates (during the tested period of treatment. "A diluting" effect of unhydrated cement residues upon the values of decomposition enthalpies in the studied multiphase system is postulated and discussed

  18. Influence of curing conditions on lime and lime-metakaolin mortars

    OpenAIRE

    Faria, Paulina; Martins, A

    2011-01-01

    Comunicação apresentada ao XII DBMC - International Conference on Durability of Building Materials and Components, Porto, April 12th-15th, 2011 Air-lime mortars with or without pozzolanic components were largely used in historic buildings. Due to natural or accidental degradation it is often necessary the application of repair mortars, durable and compatible with the masonries of historic buildings. Within this context and associating the improvement of mortars characteristics to the ne...

  19. Mechanical and leaching behaviour of slag-cement and lime-activated slag stabilised/solidified contaminated soil.

    Science.gov (United States)

    Kogbara, Reginald B; Al-Tabbaa, Abir

    2011-05-01

    Stabilisation/solidification (S/S) is an effective technique for reducing the leachability of contaminants in soils. Very few studies have investigated the use of ground granulated blast furnace slag (GGBS) for S/S treatment of contaminated soils, although it has been shown to be effective in ground improvement. This study sought to investigate the potential of GGBS activated by cement and lime for S/S treatment of a mixed contaminated soil. A sandy soil spiked with 3000mg/kg each of a cocktail of heavy metals (Cd, Ni, Zn, Cu and Pb) and 10,000mg/kg of diesel was treated with binder blends of one part hydrated lime to four parts GGBS (lime-slag), and one part cement to nine parts GGBS (slag-cement). Three binder dosages, 5, 10 and 20% (m/m) were used and contaminated soil-cement samples were compacted to their optimum water contents. The effectiveness of the treatment was assessed using unconfined compressive strength (UCS), permeability and acid neutralisation capacity (ANC) tests with determination of contaminant leachability at the different acid additions. UCS values of up to 800kPa were recorded at 28days. The lowest coefficient of permeability recorded was 5×10(-9)m/s. With up to 20% binder dosage, the leachability of the contaminants was reduced to meet relevant environmental quality standards and landfill waste acceptance criteria. The pH-dependent leachability of the metals decreased over time. The results show that GGBS activated by cement and lime would be effective in reducing the leachability of contaminants in contaminated soils. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. LIMING AND FERTILIZING FOR MAHOGANI (Switenia macrophylla King. SEEDLING FORMATION

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Franco Tucci

    2007-09-01

    Full Text Available The production of seedlings is one of the most important phases of the cultivation of forest species. Seedlings ofappropriate quality are fundamental in the growth and development of the species. In the production of seedlings, the substratum isfundamental for the good development of the plants. However, the subsoil in general, is acid and it contains low levels of nutritious.The acidity of the soil and the deficiency of nutrients can be corrected through liming and mineral fertilization. The objective of thepresent work was to evaluate the effect of liming and of the fertilization of the soil for the production of mahogany seedlings. Theexperiment was carried out in the period of 120 days, in the Federal University of Amazonas, UFAM. The experimental design wasrandomized complete blocks with statistical analysis in split plot. The plots were composed with eight treatments and four repetitionsand the subplots were eight sampling times of the plants. The treatments were control (natural soil, liming, corrective phosphate,fertilizing with NPK, liming + corrective phosphate, corrective phosphate + fertilizing with NPK, liming + fertilizing with NPK andliming + corrective phosphate + fertilizing with NPK. It was concluded that the associated liming and corrective phosphate and withthe fertilizing with nitrogen, phosphorous and potassium promoted the smallest levels of exchangeable aluminum and the largestlevels of calcium, magnesium, phosphorous and potassium in the soil. These levels of nutrients in the soil caused larger levels ofnutrients in the plants, providing larger growth rate. The liming, corrective phosphate and fertilizing are a fundamental practices inthe formation of mahogany seedlings.

  1. Effect of lime concentration on gelatinized maize starch dispersions properties.

    Science.gov (United States)

    Lobato-Calleros, C; Hernandez-Jaimes, C; Chavez-Esquivel, G; Meraz, M; Sosa, E; Lara, V H; Alvarez-Ramirez, J; Vernon-Carter, E J

    2015-04-01

    Maize starch was lime-cooked at 92 °C with 0.0-0.40% w/w Ca(OH)2. Optical micrographs showed that lime disrupted the integrity of insoluble remnants (ghosts) and increased the degree of syneresis of the gelatinized starch dispersions (GSD). The particle size distribution was monomodal, shifting to smaller sizes and narrower distributions with increasing lime concentration. X-ray patterns and FTIR spectra showed that crystallinity decreased to a minimum at lime concentration of 0.20% w/w. Lime-treated GSD exhibited thixotropic and viscoelastic behaviour. In the linear viscoelastic region the storage modulus was higher than the loss modulus, but a crossover between these moduli occurred in the non-linear viscoelastic region. The viscoelastic properties decreased with increased lime concentration. The electrochemical properties suggested that the amylopectin-rich remnants and the released amylose contained in the continuous matrix was firstly attacked by calcium ions at low lime levels (<0.20% w/w), disrupting the starch gel microstructure.

  2. Phytochemical fingerprints of lime honey collected in serbia.

    Science.gov (United States)

    Gašić, Uroš; Šikoparija, Branko; Tosti, Tomislav; Trifković, Jelena; Milojković-Opsenica, Dušanka; Natić, Maja; Tešić, Živoslav

    2014-01-01

    Composition of phenolic compounds and the sugar content were determined as the basis for characterization of lime honey from Serbia. Particular attention was given to differences in phytochemical profiles of ripe and unripe lime honey and lime tree nectar. Melissopalynological analysis confirmed domination of Tilia nectar in all analyzed samples. Phenolic acids, abscisic acid, flavonoids, and flavonoid glycosides were determined by means of ultra-HPLC coupled with a hybrid mass spectrometer (UHPLC-OrbiTrap). Sugar content was determined using high-performance anion-exchange chromatography with amperometric detection. Similar phenolic compounds characterized unripe and ripe honeys, while the lime tree nectar profile showed notable differences. Compared to lime tree nectar, a high amount of chrysin, pinocembrin, and galangin were detected in both ripe and unripe lime honey. Fructose and glucose were the major constituents of all investigated samples, and amounts were within the limits established by European Union legislation. Sucrose content in the nectar sample was up to two-fold higher when compared to all honey samples. Isomaltose and gentiobiose with turanose content were different in analyzed production stages of lime honey.

  3. Stabilization of Expansive Soil by Lime and Fly Ash

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ji-ru; CAO Xing

    2002-01-01

    An experimental program was undertaken to study the individual and admixed effects of lime and fly ash on the geotechnical characteristics of expansive soil. Lime and fly ash were added to the expansive soil at 4% -6% and 40% - 50% by dry weight of soil, respectively. Testing specimens were determined and examined in chemical composition, grain size distribution, consistency limits, compaction, CBR ,free swell and swell capacity. The effect of lime and fly ash addition on reducing the swelling potential of an expansive soil is presented.It is revealed that a change of expansive soil texture takes place when lime and fly ash are mixed with expansive soil. Plastic limit increases by mixing lime and liquid limit decreases by mixing fly ash, which decreases plasticity index. As the amount of lime and fly ash is increased, there are an apparent reduction in maximum dry density,free swell and swelling capacity under 50 kPa pressure, and a corresponding increase in the percentage of coarse particles, optimum moisture content and CBR value. Based on the results, it can be concluded that the expansive soil can be successfully stabilized by lime and fly ash.

  4. Performance of lime-BHA solidified plating sludge in the presence of Na2SiO3 and Na2CO3.

    Science.gov (United States)

    Piyapanuwat, Rungroj; Asavapisit, Suwimol

    2011-09-01

    This research investigated the performance of lime-BHA (black rice husk ash) solidified plating sludge with 2 wt% NaO from Na(2)SiO(3) and Na(2)CO(3) at the level of 0, 30 and 50 wt%. The sludge was evaluated for strength development, leachability, solution chemistry and microstructure. The lime-BHA solidified plating sludge with Na(2)SiO(3) and Na(2)CO(3) had higher early strength when compared to the control. The addition of Na(2)SiO(3) and Na(2)CO(3) increased the OH(-) concentration and decreased the Ca(2+) and heavy metal ions in solution after the first minute. The XRD patterns showed that the addition of Na(2)SiO(3) resulted in the formation of calcium silicate hydrates, while the addition of Na(2)CO(3) resulted in CaCO(3). The heavy metals from the plating sludge, especially Zn, were immobilized in calcium zincate and calcium zinc silicate forms for the lime-BHA with and without Na(2)SiO(3) solidified wastes, while samples with Na(2)CO(3) contained Zn that was fixed in the form of CaZnCO(3). The cumulative leaching of Fe, Cr and Zn from the lime-BHA solidified plating sludge decreased significantly when activators were added, especially Na(2)CO(3).

  5. Formation of porous gas hydrates

    CERN Document Server

    Salamatin, Andrey N

    2015-01-01

    Gas hydrates grown at gas-ice interfaces are examined by electron microscopy and found to have a submicron porous texture. Permeability of the intervening hydrate layers provides the connection between the two counterparts (gas and water molecules) of the clathration reaction and makes further hydrate formation possible. The study is focused on phenomenological description of principal stages and rate-limiting processes that control the kinetics of the porous gas hydrate crystal growth from ice powders. Although the detailed physical mechanisms involved in the porous hydrate formation still are not fully understood, the initial stage of hydrate film spreading over the ice surface should be distinguished from the subsequent stage which is presumably limited by the clathration reaction at the ice-hydrate interface and develops after the ice grain coating is finished. The model reveals a time dependence of the reaction degree essentially different from that when the rate-limiting step of the hydrate formation at...

  6. Frictional properties of simulated anhydrite-dolomite fault gouge and implications for seismogenic potential

    NARCIS (Netherlands)

    Pluymakers, A.M.H.; Niemeijer, A.R.; Spiers, C.J.

    2016-01-01

    The frictional properties of anhydrite-dolomite fault gouges, and the effects of CO2 upon them, are of key importance in assessing the risks associated with CO2 storage in reservoir formations capped by anhydrite-dolomite sequences, and in understanding seismicity occurring in such formations (such

  7. Surface chemistry allows for abiotic precipitation of dolomite at low temperature.

    Science.gov (United States)

    Roberts, Jennifer A; Kenward, Paul A; Fowle, David A; Goldstein, Robert H; González, Luis A; Moore, David S

    2013-09-03

    Although the mineral dolomite is abundant in ancient low-temperature sedimentary systems, it is scarce in modern systems below 50 °C. Chemical mechanism(s) enhancing its formation remain an enigma because abiotic dolomite has been challenging to synthesize at low temperature in laboratory settings. Microbial enhancement of dolomite precipitation at low temperature has been reported; however, it is still unclear exactly how microorganisms influence reaction kinetics. Here we document the abiotic synthesis of low-temperature dolomite in laboratory experiments and constrain possible mechanisms for dolomite formation. Ancient and modern seawater solution compositions, with identical pH and pCO2, were used to precipitate an ordered, stoichiometric dolomite phase at 30 °C in as few as 20 d. Mg-rich phases nucleate exclusively on carboxylated polystyrene spheres along with calcite, whereas aragonite forms in solution via homogeneous nucleation. We infer that Mg ions are complexed and dewatered by surface-bound carboxyl groups, thus decreasing the energy required for carbonation. These results indicate that natural surfaces, including organic matter and microbial biomass, possessing a high density of carboxyl groups may be a mechanism by which ordered dolomite nuclei form. Although environments rich in organic matter may be of interest, our data suggest that sharp biogeochemical interfaces that promote microbial death, as well as those with high salinity may, in part, control carboxyl-group density on organic carbon surfaces, consistent with origin of dolomites from microbial biofilms, as well as hypersaline and mixing zone environments.

  8. Effect of dolomite oral exposure in Wistar rats during organogenesis period of pregnancy.

    Science.gov (United States)

    Lagarto, Alicia; Bellma, Addis; Tillán, Juana; Gabilondo, Tatiana; Guerra, Isbel; Ocanto, Zuleira; Couret, Micaela; González, Ricardo

    2008-09-01

    The potential of oral exposure to dolomite, a natural product that contains calcium and magnesium, to initiate teratogenesis was analyzed in Wistar rats. Animals received dolomite oral dosages of 500 and 1500mg/kg during the period of gestation from day 6-15 post conceptionem (p.c.). Maternal, embryo and fetal toxicity were evaluated. Dolomite exposure did not produce maternal toxicity assessed by clinical observations, body weight gain, hematology parameters and relative organs weight. Signs of embryo-fetal toxicity were not observed. Skeletal malformations and visceral variations were similar in control and dolomite-treated groups. On the other hand, slight increase was observed in fetal body weight in the dolomite-treated group. Treatment with dolomite resulted in significantly decreased incidences of unossified xiphisternum, incomplete ossification of xiphisternum and sternebrae. These effects could be caused by a beneficial influence of calcium and magnesium salts present in dolomite on ossification process. In conclusion, in this study we found that the oral exposure to rats of up to 1500mg/kg of dolomite during organogenesis did not induce significant maternal and embryo-fetal toxicity.

  9. Dolomite supplementation improves bone metabolism through modulation of calcium-regulating hormone secretion in ovariectomized rats.

    Science.gov (United States)

    Mizoguchi, Toshihide; Nagasawa, Sakae; Takahashi, Naoyuki; Yagasaki, Hiroshi; Ito, Michio

    2005-01-01

    Dolomite, a mineral composed of calcium magnesium carbonate (CaMg (CO3)2), is used as a food supplement that supplies calcium and magnesium. However, the effect of magnesium supplementation on bone metabolism in patients with osteoporosis is a matter of controversy. We examined the effects of daily supplementation with dolomite on calcium metabolism in ovariectomized (OVX) rats. Dolomite was administered daily to OVX rats for 9 weeks. The same amount of magnesium chloride as that supplied by the dolomite was given to OVX rats as a positive control. Histological examination revealed that ovariectomy decreased trabecular bone and increased adipose tissues in the femoral metaphysis. Dolomite or magnesium supplementation failed to improve these bone histological features. Calcium content in the femora was decreased in OVX rats. Neither calcium nor magnesium content in the femora in OVX rats was significantly increased by dolomite or magnesium administration. Urinary deoxypyridinoline excretion was significantly increased in OVX rats, and was not affected by the magnesium supplementation. Serum concentrations of magnesium were increased, and those of calcium were decreased, in OVX rats supplemented with dolomite or magnesium. However, there was a tendency toward decreased parathyroid hormone secretion and increased calcitonin secretion in OVX rats supplemented with dolomite or magnesium. Serum 1,25-dihydroxyvitamin D(3) and osteocalcin levels were significantly increased in the supplemented OVX rats. These results suggest that increased magnesium intake improves calcium metabolism in favor of increasing bone formation, through the modulation of calcium-regulating hormone secretion.

  10. Carbon dioxide absorption and release properties of pyrolysis products of dolomite calcined in vacuum atmosphere.

    Science.gov (United States)

    Wang, Fei; Kuzuya, Toshihiro; Hirai, Shinji; Li, Jihua; Li, Te

    2014-01-01

    The decomposition of dolomite into CaO and MgO was performed at 1073 K in vacuum and at 1273 K in an Ar atmosphere. The dolomite calcined in vacuum was found to have a higher specific surface area and a higher micropore volume when compared to the dolomite calcined in the Ar atmosphere. These pyrolysis products of dolomite were reacted with CO2 at 673 K for 21.6 ks. On the absorption of CO2, the formation of CaCO3 was observed. The degree of absorption of the dolomite calcined in vacuum was determined to be above 50%, which was higher than the degree of absorption of the dolomite calcined in the Ar atmosphere. The CO2 absorption and release procedures were repeated three times for the dolomite calcined in vacuum. The specific surface area and micropore volume of calcined dolomite decreased with successive repetitions of the CO2 absorption and release cycles leading to a decrease in the degree of absorption of CO2.

  11. Presence of sulfate does not inhibit low-temperature dolomite precipitation

    Science.gov (United States)

    Sánchez-Román, Mónica; McKenzie, Judith A.; de Luca Rebello Wagener, Angela; Rivadeneyra, Maria A.; Vasconcelos, Crisógono

    2009-07-01

    The hypothesis that sulfate inhibits dolomite formation evolved from geochemical studies of porewaters from deep-sea sedimentary sequences and has been tested with hydrothermal experiments. We examined the sulfate inhibition factor using aerobic culture experiments with Virgibacillus marismortui and Halomonas meridiana, two moderately halophilic aerobic bacteria, which metabolize independent of sulfate concentration. The culture experiments were conducted at 25 and 35 °C using variable SO 42- concentrations (0, 14, 28 and 56 mM) and demonstrate that halophilic aerobic bacteria mediate direct precipitation of dolomite with or without SO 42- in the culture media which simulate dolomite occurrences commonly found under the Earth's surface conditions. Hence, we report that the presence of sulfate does not inhibit dolomite precipitation. Further, we hypothesize that, if sedimentary dolomite is a direct precipitate, as in our low-temperature culture experiments, the kinetic factors involved are likely to be quite different from those governing a dolomite replacement reaction, such as in hydrothermal experiments. Consequently, the occurrence and, presumably, growth of dolomite in SO 42--rich aerobic cultures may shed new light on the long-standing Dolomite Problem.

  12. Tectonics of the crystalline Basement of the Dolomites in North Italy

    NARCIS (Netherlands)

    Agterberg, F.P.

    1961-01-01

    The present thesis deals with a number of crystalline regions around the Dolomites in North Italy. The geographic position is shown on sheet I, which is depicted in fig. 105. The Dolomites proper consist mainly of Permotriassic, overlying a transgression plane, which cuts off the studied crystalline

  13. 煅烧工艺制度对轻烧白云石活性度的影响%Effect of calcining process and system on reactivity of soft-burnt dolomite

    Institute of Scientific and Technical Information of China (English)

    高华

    2012-01-01

    The effect of calcining processes on the reactivity three kinds of soft-burnt dolomites is studied through calcining test and observation of microstructure. It is concluded as follows : ( 1 ) soaking time is 90 minutes,, there is a trend in which the reactivity of soft-burnt dolomite is increased first with the calcining temperature uprising and then decreased. At 1 050℃ the reactivity of soft-burnt dolomite reaches the highest value; (2) for some calcining temperature, there is a period of calcining time to make soft-burnt lime have a highest reactivity value ; (3) the grain size of the dolomite tobe calcined has influence on the reactivity of the calcined product; (4) the microstructure of the raw dolomite has great influence on the reactivity of the calcined product, generally the raw dolomite with coarse and big crystals is easy to obtain the calcined product with higher reactivity.%通过煅烧实验和显微结构观察,研究了煅烧工艺对三种自云石轻烧后活性度的影响,得出如下结论:(1)保温时间为90min,随煅烧温度提高轻烧白云石的活性呈现先升高、后降低的趋势,在1050℃活性度达到最高点。(2)对应某煅烧温度存在一个煅烧时间使轻烧白云石活性最高。(3)白云石的煅烧颗粒尺寸影响煅烧产物活性度。(4)白云石原矿的显微结构对煅烧产物活性度有很大影响,一般晶粒粗大的原矿易得到活性较高的煅烧产物。

  14. Lime stabilization of fine-grained sediments in western Greenland

    DEFF Research Database (Denmark)

    Jørgensen, Anders Stuhr; Ingeman-Nielsen, Thomas; Skels, Peteris

    2011-01-01

    due to the cold climate, and it is therefore of great interest to study possible methods to improve the stability and strength properties. This project includes laboratory studies of lime stabilization on fine-grained marine sediments from Kangerlussuaq, western Greenland. The results have included...... tests to determine the optimum lime content and the strength development in relation to both reaction time and curing temperature. Hopefully the results from this project will lead to a future use of lime stabilization and make it possible to use/reuse materials of poor quality at construction sites...

  15. [Hydration in clinical practice].

    Science.gov (United States)

    Maristany, Cleofé Pérez-Portabella; Segurola Gurruchaga, Hegoi

    2011-01-01

    Water is an essential foundation for life, having both a regulatory and structural function. The former results from active and passive participation in all metabolic reactions, and its role in conserving and maintaining body temperature. Structurally speaking it is the major contributer to tissue mass, accounting for 60% of the basis of blood plasma, intracellular and intersticial fluid. Water is also part of the primary structures of life such as genetic material or proteins. Therefore, it is necessary that the nurse makes an early assessment of patients water needs to detect if there are signs of electrolyte imbalance. Dehydration can be a very serious problem, especially in children and the elderly. Dehydrations treatment with oral rehydration solution decreases the risk of developing hydration disorders, but even so, it is recommended to follow preventive measures to reduce the incidence and severity of dehydration. The key to having a proper hydration is prevention. Artificial nutrition encompasses the need for precise calculation of water needs in enteral nutrition as parenteral, so the nurse should be part of this process and use the tools for calculating the patient's requirements. All this helps to ensure an optimal nutritional status in patients at risk. Ethical dilemmas are becoming increasingly common in clinical practice. On the subject of artificial nutrition and hydration, there isn't yet any unanimous agreement regarding hydration as a basic care. It is necessary to take decisions in consensus with the health team, always thinking of the best interests of the patient.

  16. 3D-Mapping of Dolomitized Structures in Lower Cambrian Phosphorites

    Science.gov (United States)

    Hippler, Dorothee; Stammeier, Jessica A.; Brunner, Roland; Rosc, Jördis; Franz, Gerhard; Dietzel, Martin

    2016-04-01

    Dolomitization is a widespread phenomenon in ancient sedimentary rocks, particularly close to the Precambrian-Cambrian boundary. Dolomite can form in synsedimentary or hydrothermal environments, preferentially via the replacement of solid carbonate precursor phases. Synsedimentary dolomite formation is often associated with microbial activity, such as bacterial sulfate reduction or methanogenesis. In this study, we investigate dolomitic phosphorites from the Lowermost Cambrian Tal Group, Mussoori Syncline, Lesser Himalaya, India, using micro-CT 3D-mapping, in order to unravel the complex diagenetic history of the rocks. The selected sample shows alternating layering of phosphatic mudstones and sparitic dolostone, in which brecciated layers of phosphorite or phosphatic mudstones are immersed in a dolomite-rich matrix. Lamination occurs on a sub-millimetre scale, with lamination sometimes wavy to crinkly. This fabric is interpreted as former microbial mats, providing the environment for early diagenetic phosphatization. Preliminary electron backscatter imaging with scanning microscopy revealed that dolomite crystals often occur in spherical to ellipsoidal structures, typically with a high porosity. This dolomite is associated with botryoidal apatite, organic matter and small amounts of calcite. Micro-CT 3D-mappings reveal that dolomite structures are cigar-shaped, elongated and up to 600 μm long. They are further arranged in a Mikado-like oriented framework spanning a layer thickness of a few millimetres. Analyses of ambient pore space, with similar elongated outlines and filled with organic matter, suggest a potential coherence of ambient pore space and shape of the dolomite structures. Allowing for other associated mineral phases, such as pyrite and silicates, and their spatial distribution, the present approach can be used to unravel distinct diagenetic reaction pathways, and might thus constrain the proxy potential of these Lower Cambrian dolomitic phosphorites

  17. Soil pH management without lime, a strategy to reduce greenhouse gas emissions from cultivated soils

    Science.gov (United States)

    Nadeem, Shahid; Bakken, Lars; Reent Köster, Jan; Tore Mørkved, Pål; Simon, Nina; Dörsch, Peter

    2015-04-01

    For decades, agricultural scientists have searched for methods to reduce the climate forcing of food production by increasing carbon sequestration in the soil and reducing the emissions of nitrous oxide (N2O). The outcome of this research is depressingly meagre and the two targets appear incompatible: efforts to increase carbon sequestration appear to enhance the emissions of N2O. Currently there is a need to find alternative management strategies which may effectively reduce both the CO2 and N2O footprints of food production. Soil pH is a master variable in soil productivity and plays an important role in controlling the chemical and biological activity in soil. Recent investigations of the physiology of denitrification have provided compelling evidence that the emission of N2O declines with increasing pH within the range 5-7. Thus, by managing the soil pH at a near neutral level appears to be a feasible way to reduce N2O emissions. Such pH management has been a target in conventional agriculture for a long time, since a near-neutral pH is optimal for a majority of cultivated plants. The traditional way to counteract acidification of agricultural soils is to apply lime, which inevitably leads to emission of CO2. An alternative way to increase the soil pH is the use of mafic rock powders, which have been shown to counteract soil acidification, albeit with a slower reaction than lime. Here we report a newly established field trail in Norway, in which we compare the effects of lime and different mafic mineral and rock powders (olivine, different types of plagioclase) on CO2 and N2O emissions under natural agricultural conditions. Soil pH is measured on a monthly basis from all treatment plots. Greenhouse gas (GHG) emission measurements are carried out on a weekly basis using static chambers and an autonomous robot using fast box technique. Field results from the first winter (fallow) show immediate effect of lime on soil pH, and slower effects of the mafic rocks. The

  18. Re-evaluation of temperature of replacement dolomitization in the Triassic Latemar platform with clumped isotope thermometry

    Science.gov (United States)

    Müller, Inigo Andreas; Rodriguez-Blanco, Juan D.; Storck, Julian-Christopher; Benning, Liane G.; Wilson, Edith N.; Brack, Peter; Bernasconi, Stefano M.

    2017-04-01

    The Triassic Latemar platform shows different types of dolomitization styles including features such as dolomitized zones around basaltic dykes and patchy reddish or greyish dolomitization features in the central part of the platform. The processes leading to this partial dolomitization are still debated. Different geochemical tools were applied to determine the formation temperature of the patchy dolomite phases, thereby microthermometry on fluid inclusions and clumped isotope thermometry revealed significantly different temperature ranges (100 to 200 °C vs. 40 to 80 °C, from Wilson et al., 1990 and Ferry et al., 2011, respectively). We re-evaluated the origin of these patchy dolomites at Latemar using a new dolomite-specific clumped isotope temperature calibration based on dolomites synthetized in the laboratory at different temperatures. We directly compare the clumped isotope temperatures of patchy dolomites from Latemar with those obtained on the same samples by fluid inclusion microthermometry. With the new dolomite specific clumped isotope temperature calibration it is possible to determine more precisely the dolomite formation temperature and the oxygen isotope composition of the fluid source. Both are critical parameters for better constraining the origin of different dolomite fabrics on the Earth's surface and in ancient sediments. E.N. Wilson, L.A. Hardie and O.M. Phillips, 1990. Dolomitization front geometry, fluid flow patterns, and the origin of massive dolomite: the Triassic Latemar buildup, northern Italy. American Journal of Science 290, 741-796. J.M. Ferry, B.H. Passey, C. Vasconcelos and J.M. Eiler, 2011. Formation of dolomite at 40-80 °C in the Latemar carbonate buildup, Dolomites, Italy, from clumped isotope thermometry. Geology 39, 571-574.

  19. Biofacies evolution in the Triassic platforms of the Dolomites, Italy

    Directory of Open Access Journals (Sweden)

    Franco Russo

    2005-10-01

    Full Text Available The Triassic of the Dolomites includes many carbonate platform generations, ranging in age from the Anisian to the Norian-Rhaetian. After the Permian-Triassic biological crisis, “reef” communities reappeared during the Anisian time. These buildups were generally characterized by a limited relief, lacking any primary skeletal framework and evidence of syndepositional cementation. The microfacies are dominated by micrites, mainly allochthonous or detrital in origin. The sparse biota are generally binder and buffler organisms, such as dasycladacean algae, sphinctozoans and briozoans.The second generation of carbonate buildups (late Anisian–early Ladinian, Sciliar Fm are dominated by syndepositional cements (e.g. Marmolada Platform. These cements represent the main component of margin and upper slope facies. They form more or less isolated or laterally linked bodies: the “evinosponges”. During the late Ladinian and Carnian p.p., the post-volcanic platforms developed (Cassian Dolomite. The microfacies of these platforms manly consist of micrites, cements and skeletons. The automicrites constitute more than 50% of the rock volume, the cements the 20%, and the skeletal organisms less than the 10%. The metazoan contribution is subordinated to that of skeletal cyanobacteria, like Cladogirvanella cipitensis and microproblematica, like Tubyphites. The primary marine cements provide evidence of a widespread early syndepositional lithification. Towards the top of Julian Substage (Carnian, at the base of the Heiligkreutz/Dürrenstein Formation (i.e. Alpe di Specie, small calcareous bioconstructions, interpreted as patch-reefs, show a much more “modern” faunal association. For the first time in the Triassic, a primary skeletal framework developed, largely formed by calcified demosponges and scleractinians. Corals were still subordinated to sponges. Taxonomic diversity increases greatly and the skeletal component exceeds the 50% of the rock volume

  20. 40 CFR 63.7143 - What definitions apply to this subpart?

    Science.gov (United States)

    2010-07-01

    ... lime or calcium hydroxide via the chemical reaction of the lime product with water. Lime cooler means... kiln calcination process including, calcitic lime, dolomitic lime, and dead-burned dolomite....

  1. Incorporation of turmeric-lime mixture during the preparation of ...

    African Journals Online (AJOL)

    GREGO

    2007-03-19

    Mar 19, 2007 ... new type of turmeric-lime treated tomato puree product. ... Retention of natural pigment is one of the symbols of livelihood. Thermal treatment is one of the most important methods of preservation of vegetables (Lund, 1975).

  2. Effects of liming; Effekter av kalkning. IKEU aarsrapport 1994

    Energy Technology Data Exchange (ETDEWEB)

    Appelberg, M. [Institute for Freshwater Research, Drottningholm (Sweden)

    1995-11-01

    Since 1989 an extensive investigation have been made of 14 limed lakes in Sweden. On a regular basis monitoring is made of the water chemistry, nutrients and metals in fish, plankton and bottom fauna. This report covers the result from 1994 as well as a compilation of the trend during 1989-1994. The aim of the monitoring programme is (1) to analyze the long-term chemical and biological effects of liming of acidified waters, (2) to evaluate if the Swedish liming program restores the ecosystems with regard to species composition and biological richness, (3) to judge if the liming efforts leads to unwanted effects in lakes and water courses, and (4) to be able to forecast the capacity of the acidified lakes to return to pre-acidification conditions and to compare this to costs and risks for unwanted effects. 16 refs, 70 figs, 2 tabs

  3. Damage Development in Confined Borosilicate and Soda-Lime Glasses

    Science.gov (United States)

    2011-07-11

    Elmira, NY). BF is a borosilicate glass manufactured by Schott Glass using a float process. SP float glass is a crystal clear, soda-lime glass . This...2005. 22 21. ASTM £494, "Technique for Measuring Ultrasonic Velocity in Materials", July 2001. 22. Schott Glass , Borofloat 33 Thermal Properties...21945 Damage Development in Conf"med Borosilicate and Soda-Lime Glasses Kathryn A. Dannemann1, Charles E. Anderson. Jr. 1, Sidney Chocron1, James

  4. Property Changes in Lime Treated Expansive Clays under Continuous Leaching

    Science.gov (United States)

    1990-09-01

    decreasing soil-lime reactivity in areas of better drainage . In poorly drained soils, the removal of soil "constituents" are slowed and leaching effects are...minimized, thereby maintaining the calcium/magnesium ratio and higher soil pH (Thompson 1966; Joffe 1949). Also, soils with poor drainage will have a...these soil-lime mixtures may not exhibit as much autogenous healing, particularly after prolonged leaching, as they are generally believed to have

  5. Effects of liming on crayfish and fish in Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Nyberg, P.; Appleberg, M.; Degerman, E.

    1986-12-01

    The effects of lime treatment on crayfish (Astacus astacus and Pacifastacus leniusculus) populations in 17 lakes and fish populations in 47 lakes and 7 rivers within the trial period 1976-82 have been evaluated. An increase in the catch of crayfish per unit effort was observed in 7 lakes, although significantly in one lake only. The varying results in the other lakes indicate that factors other than pH may be of greater importance for the development of crayfish populations after liming. Recruitment of fish improved in waters where liming resulted in pH <5.5. In lakes with pH <5.5 before and pH >5.5 after treatment, there was a significant increase in the number of fish caught, from 12 to 34 per unit effort. Due to improved recruitment the individual average weight was smaller and hence the catch in weight per unit effort was about the same as before liming. After lime treatment in streams which resulted in a stable pH of >5.5, the abundance of juvenile salmonids increased to numbers found in non-acidified streams. In other streams acid spates reduced the positive influence of liming on the abundance of juvenile salmonids. 33 references.

  6. Kinetic and Thermodynamic Studies on the Phosphate Adsorption Removal by Dolomite Mineral

    Directory of Open Access Journals (Sweden)

    Xiaoli Yuan

    2015-01-01

    Full Text Available The efficiency of dolomite to remove phosphate from aqueous solutions was investigated. The experimental results showed that the removal of phosphate by dolomite was rapid (the removal rate over 95% in 60 min when the initial phosphate concentration is at the range of 10–50 mg/L. Several kinetic models including intraparticle diffusion model, pseudo-first-order model, Elovich model, and pseudo-second-order model were employed to evaluate the kinetics data of phosphate adsorption onto dolomite and pseudo-second-order model was recommended to describe the adsorption kinetics characteristics. Further analysis of the adsorption kinetics indicated that the phosphate removal process was mainly controlled by chemical bonding or chemisorption. Moreover, both Freundlich and Langmuir adsorption isotherms were used to evaluate the experimental data. The results indicated that Langmuir isotherm was more suitable to describe the adsorption characteristics of dolomite. Maximum adsorption capacity of phosphate by dolomite was found to be 4.76 mg phosphorous/g dolomite. Thermodynamic studies showed that phosphate adsorption was exothermic. The study implies that dolomite is an excellent low cost material for phosphate removal in wastewater treatment process.

  7. Precipitation of low-temperature dolomite from an anaerobic microbial consortium: the role of methanogenic Archaea.

    Science.gov (United States)

    Kenward, P A; Goldstein, R H; González, L A; Roberts, J A

    2009-12-01

    Here we report precipitation of dolomite at low temperature (30 degrees C) mediated by a mixed anaerobic microbial consortium composed of dissimilatory iron-reducing bacteria (DIRB), fermenters, and methanogens. Initial solution geochemistry is controlled by DIRB, but after 90 days shifts to a system dominated by methanogens. In live experiments conditions are initially saturated with respect to dolomite (Omega(dol) = 19.40) and increase by two orders of magnitude (Omega(dol) = 2 330.77) only after the onset of methanogenesis, as judged by the increasing [CH(4)] and the detection of methanogenic micro-organisms. We identify ordered dolomite in live microcosms after 90 days via powder X-ray diffraction, while sterile controls precipitate only calcite. Scanning electron microscopy and transmitted electron microscopy demonstrate that the precipitated dolomite is closely associated with cell walls and putative extra-cellular polysaccharides. Headspace gas measurements and denaturing gradient gel electrophoresis confirm the presence of both autotrophic and acetoclastic methanogens and exclude the presence of DIRB and sulfate-reducing bacteria after dolomite begins forming. Furthermore, the absence of dolomite in the controls and prior to methanogenesis confirm that methanogenic Archaea are necessary for the low-temperature precipitation of dolomite under the experimental conditions tested.

  8. Molecular characterization of endolithic cyanobacteria inhabiting exposed dolomite in central Switzerland.

    Science.gov (United States)

    Sigler, William V; Bachofen, Reinhard; Zeyer, Josef

    2003-07-01

    The phototrophic microbial community inhabiting exposed dolomite in the alpine Piora Valley (Switzerland) forms a distinct endolithic bilayer that features adjacent red dolomite (exterior) and green dolomite (interior) layers that are c. 0.5-1 mm below the rock surface. Characterization of the community, with an emphasis on cyanobacteria, was conducted with culture-dependent and -independent approaches. Direct microscopy of green dolomite revealed four distinct morphotypes consistent with Chlorophyta genera Chlorella and Stichococcus and the Cyanobacterial genera Nostoc and Calothrix, whereas only Stichococcus and Nostoc were observed in the red dolomite. Enrichment in BG-11 media resulted in the growth of Chlorella and Stichococcus. Denaturing gradient gel electrophoresis (DGGE) analysis of DNA extracted from the enrichment revealed two dominant phylotypes with sequence similarity to Chlorella osrokiniana chloroplast and the cyanobacteria genus Leptolyngbya. 16S rRNA gene-based DGGE analysis of DNA extracted directly from both layers indicated that although both layers harboured phylotypes most similar to the Cyanobacterial genera Nostoc, Chroococcidiopsis, and Microcoleus, and the Chlorophyte Stichococcus bacillaris, the two layers also harboured unique genera such as Scytonema, and Symploca (red, external layer of dolomite) and Chlorella (green, internal layer of dolomite). The unique community structure of each layer suggests a selection process directed by the pressures of the endolithic environment. We conclude that the overall composition of the phototrophic community closely resembles that of endolithic communities located in extreme habitats, suggesting that a cosmopolitan community inhabits this defined niche.

  9. Adsorption of Cu2+ and Pb2+ ion on dolomite powder.

    Science.gov (United States)

    Pehlivan, Erol; Ozkan, Ali Müjdat; Dinç, Salih; Parlayici, Serife

    2009-08-15

    Natural Turkish dolomite was shown to be effective for removing Cu(2+) and Pb(2+) from aqueous solution. Selected information on pH, dose required, initial metal concentration, adsorption capacity of the raw dolomite powder was evaluated for its efficiency in adsorbing metal ions. Dolomite exhibited good Cu(2+) and Pb(2+) removal levels at all initial metal amount tested (0.04-0.32 mmol, 20 mL). It is important to note that the adsorption capacities of the materials in equilibrium vary, depending on the characteristics of the individual adsorbent, the initial concentration of the adsorbate and pH of the solution. One hour was enough for the removal of metal ions from (0.2 mmol in 20 mL) aqueous solution. Effective removal of metal ions was demonstrated at pH values of 5.0. The adsorptive behavior of dolomite was described by fitting data generated from the study of the Langmuir and Freundlich isotherm models. The adsorption capacity of dolomite was found as 8.26 mg for Cu(2+) and 21.74 mg for Pb(2+), respectively, from the calculation of adsorption isotherm equation. More than 85% of studied cations were removed by dolomite from aqueous solution in single step. The mechanism for cations removal by dolomite includes surface complexation and ion exchange.

  10. Dolomite-magnesian calcite relations at elevated temperatures and CO2 pressures

    Science.gov (United States)

    Graf, D.L.; Goldsmith, J.R.

    1955-01-01

    The equilibrium thermal decomposition curve of dolomite has been determined up to a CO2 pressure of 20,000 lb/in.2, at which pressure dolomite decomposes at 857??C. Equilibrium was approached from both directions, by the breakdown and by the solid-state synthesis of dolomite. At elevated temperatures and pressures, calcites in equilibrium with periclase as well as those in equilibrium with dolomite contain Mg in solid solution. In the former, the Mg content increases with increasing CO2 pressure, and decreases with increasing temperature. In the latter, it is a function of temperature only. The exsolution curve of dolomite and magnesian calcite has been determined between 500?? and 800??C; at 500?? dolomite is in equilibrium with a magnesian calcite containing ~6 mol per cent MgCO2; at 800??, ~22 mol per cent. There appears to be a small but real deviation from the ideal 1 : 1 Ca : Mg ratio of dolomite, in the direction of excess Ca, for material in equilibrium with magnesian calcite at high temperature. The experimental findings indicate that very little Mg is stable in the calcites of sedimentary environments, but that an appreciable amount is stable under higher-temperature metamorphic conditions, if sufficient CO2 pressure is maintained. ?? 1955.

  11. Optimasi Dosis Pupuk Dolomit pada Tanaman Kelapa Sawit (Elaeis Guineensis Jacq. Belum Menghasilkan Umur Satu Tahun

    Directory of Open Access Journals (Sweden)

    - Sudradjat

    2015-09-01

    Full Text Available Kelapa sawit merupakan komoditi perkebunan utama karena sebagai sumber devisa negara dan menyediakan lapangan kerja. Indonesia adalah negara produsen terbesar kelapa sawit di dunia dengan luas areal mencapai 10.1 juta hektar. Peningkatan produktivitas dicapai dengan intensifikasi antara lain dengan melakukan rasionalisasi pemupkan. Penelitian ini bertujuan untuk menentukan dosis optimum pupuk dolomit pada tanaman kelapa sawit belum menghasilkan umur satu tahun. Penelitian ini dilaksanakan di Kebun Pendidikan dan Penelitian Kelapa Sawit IPB-Cargill, Jonggol, Bogor dari bulan Maret 2013 sampai Maret 2014. Rancangan yang digunakan adalah Faktorial Tunggal,  dosis pupuk dolomit,  yang disusun dalam lingkungan Acak Kelompok dengan tiga ulangan. Dosis pupuk dolomit yang diuji  terdiri atas 0, 200, 400, dan 600 g tanaman-1 tahun-1. Hasil penelitian menunjukkan bahwa pupuk dolomit meningkatkan secara nyata terhadap peubah tinggi tanaman, diameter batang, jumlah daun, dan kandungan khlorofil daun, namun tidak berpengaruh terhadap kandungan Mg dalam jaringan daun. Berdasarkan tanggap peubah tinggi tanaman, dosis optimum pupuk dolomit untuk tanaman kelapa sawit pada umur satu tahun adalah 306.4 g dolomit tanaman-1tahun -1. Kata kunci: dolomit, dosis optimum, kelapa sawit, respons fisiologi, respons morfologi.

  12. Hydrothermal dolomitization of basinal deposits controlled by a synsedimentary fault system in Triassic extensional setting, Hungary

    Science.gov (United States)

    Hips, Kinga; Haas, János; Győri, Orsolya

    2016-06-01

    Dolomitization of relatively thick carbonate successions occurs via an effective fluid circulation mechanism, since the replacement process requires a large amount of Mg-rich fluid interacting with the CaCO3 precursor. In the western end of the Neotethys, fault-controlled extensional basins developed during the Late Triassic spreading stage. In the Buda Hills and Danube-East blocks, distinct parts of silica and organic matter-rich slope and basinal deposits are dolomitized. Petrographic, geochemical, and fluid inclusion data distinguished two dolomite types: (1) finely to medium crystalline and (2) medium to coarsely crystalline. They commonly co-occur and show a gradual transition. Both exhibit breccia fabric under microscope. Dolomite texture reveals that the breccia fabric is not inherited from the precursor carbonates but was formed during the dolomitization process and under the influence of repeated seismic shocks. Dolomitization within the slope and basinal succession as well as within the breccia zones of the underlying basement block is interpreted as being related to fluid originated from the detachment zone and channelled along synsedimentary normal faults. The proposed conceptual model of dolomitization suggests that pervasive dolomitization occurred not only within and near the fault zones. Permeable beds have channelled the fluid towards the basin centre where the fluid was capable of partial dolomitization. The fluid inclusion data, compared with vitrinite reflectance and maturation data of organic matter, suggest that the ascending fluid was likely hydrothermal which cooled down via mixing with marine-derived pore fluid. Thermal gradient is considered as a potential driving force for fluid flow.

  13. New insights to the formation of modern dolomite in a terrestrial low-temperature environment

    Science.gov (United States)

    Zünterl, Andrea; Baldermann, Andre; Boch, Ronny; Dietzel, Martin

    2017-04-01

    Although dolomite [CaMg(CO3)2] is a rock-forming mineral in ancient carbonate platforms, its occurrence in modern-marine carbonate-depositing settings and in particular in terrestrial, low-temperature environments is scarce - an enigma that is referred to as the "dolomite problem". At present, it is generally accepted that microbial activity, bacterially-mediated sulfate reduction, high aqueous Mg/Ca ratios and anoxic conditions favour the nucleation and crystal growth of dolomite; albeit the precise reaction paths causing the formation of dolomite at low temperatures remain questionable. Here, we present a novel study about the environmental controls and reaction mechanisms leading to the formation of authigenic Mg-Ca carbonates in (active) fault zones of the Erzberg (Styria, Austria) - Europe's largest iron ore opencast mine. Our petrographic and mineralogical results revealed the presence of ˜2-20 cm thick laminated successions of embedded needle-shaped, radiating aragonite and blocky low-Mg calcite (a repetitive sequence also-called "erzbergite") and subsequently deposited (Ca-rich) non-stoichiometric dolomite, which is clogging former voids and unconsolidated sediment in the heavily deteriorated fault zone. First U-Th age determinations of the respective aragonite layers indicate its formation at ˜19,000-13,000 years BP, also suggesting a "young" age of the sedimentary dolomite. Based on the combination of X-ray diffraction and electron microprobe analyses we identified two types of matrix-replacing dolomite: type 1 dolomite is nearly stoichiometric (˜51 mol% CaCO3) and shows a high degree of cation ordering (0.4-0.6), whereas type 2 dolomite is characterized by Ca-excess (˜55 mol% CaCO3) and a low degree of ordering (<0.3). Both types of dolomite grow on the extent of matrix minerals, such as detrital low-Mg calcite, ankerite, siderite, quartz, goethite, chlorite and illitic clay minerals, implying a low-temperature origin of the Ca-excess dolomite and

  14. Kinetic and Thermodynamic Studies on the Phosphate Adsorption Removal by Dolomite Mineral

    OpenAIRE

    Xiaoli Yuan; Wentang Xia; Juan An; Jianguo Yin; Xuejiao Zhou; Wenqiang Yang

    2015-01-01

    The efficiency of dolomite to remove phosphate from aqueous solutions was investigated. The experimental results showed that the removal of phosphate by dolomite was rapid (the removal rate over 95% in 60 min) when the initial phosphate concentration is at the range of 10–50 mg/L. Several kinetic models including intraparticle diffusion model, pseudo-first-order model, Elovich model, and pseudo-second-order model were employed to evaluate the kinetics data of phosphate adsorption onto dolomit...

  15. Modeling Hydrates and the Gas Hydrate Markup Language

    Directory of Open Access Journals (Sweden)

    Weihua Wang

    2007-06-01

    Full Text Available Natural gas hydrates, as an important potential fuels, flow assurance hazards, and possible factors initiating the submarine geo-hazard and global climate change, have attracted the interest of scientists all over the world. After two centuries of hydrate research, a great amount of scientific data on gas hydrates has been accumulated. Therefore the means to manage, share, and exchange these data have become an urgent task. At present, metadata (Markup Language is recognized as one of the most efficient ways to facilitate data management, storage, integration, exchange, discovery and retrieval. Therefore the CODATA Gas Hydrate Data Task Group proposed and specified Gas Hydrate Markup Language (GHML as an extensible conceptual metadata model to characterize the features of data on gas hydrate. This article introduces the details of modeling portion of GHML.

  16. Overview: Nucleation of clathrate hydrates

    Science.gov (United States)

    Warrier, Pramod; Khan, M. Naveed; Srivastava, Vishal; Maupin, C. Mark; Koh, Carolyn A.

    2016-12-01

    Molecular level knowledge of nucleation and growth of clathrate hydrates is of importance for advancing fundamental understanding on the nature of water and hydrophobic hydrate formers, and their interactions that result in the formation of ice-like solids at temperatures higher than the ice-point. The stochastic nature and the inability to probe the small length and time scales associated with the nucleation process make it very difficult to experimentally determine the molecular level changes that lead to the nucleation event. Conversely, for this reason, there have been increasing efforts to obtain this information using molecular simulations. Accurate knowledge of how and when hydrate structures nucleate will be tremendously beneficial for the development of sustainable hydrate management strategies in oil and gas flowlines, as well as for their application in energy storage and recovery, gas separation, carbon sequestration, seawater desalination, and refrigeration. This article reviews various aspects of hydrate nucleation. First, properties of supercooled water and ice nucleation are reviewed briefly due to their apparent similarity to hydrates. Hydrate nucleation is then reviewed starting from macroscopic observations as obtained from experiments in laboratories and operations in industries, followed by various hydrate nucleation hypotheses and hydrate nucleation driving force calculations based on the classical nucleation theory. Finally, molecular simulations on hydrate nucleation are discussed in detail followed by potential future research directions.

  17. A study on gas hydrate

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Byoung Jae; Jung, Tae Jin; Sunwoo, Don [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)

    1996-12-01

    Sufficient documents were reviewed to understand solid components of water and gaseous hydrocarbon known as gas hydrates, which represent an important potential energy resource of the future. The review provides us with valuable information on crystal structures, kinetics, origin and distribution of gas hydrates. In addition, the review increased our knowledge of exploration and development methods of gas hydrates. Large amounts of methane, the principal component of natural gas, in the form of solid gas hydrate are found mainly offshore in outer continental margin sediment and, to a lesser extent, in polar regions commonly associated with permafrost. Natural gas hydrates are stable in some environments where the hydrostatic pressure exerted by overlying water column is sufficient for hydrate formation and stability. The required high pressures generally restrict gas hydrate to sediments beneath water of approximately 400 m. Higher sediment temperatures at greater subbottom depths destabilize gas hydrates. Based on the pressure- temperature condition, the outer continental margin of East Sea where water depth is deep enough to form gas hydrate is considered to have high potential of gas hydrate accumulations. (author). 56 refs., tabs., figs.

  18. Dolomite-Derived Ni-Based Catalysts with Fe Modification for Hydrogen Production via Auto-Thermal Reforming of Acetic Acid

    Directory of Open Access Journals (Sweden)

    Xinyan Zhong

    2016-06-01

    Full Text Available Bio-oil can be obtained via fast pyrolysis of biomass, and typically contains acetic acid (~30 mass %. The acetic acid has often been tested as a model compound for hydrogen production via reforming bio-oil, in which catalysts are a key factor for stable hydrogen production. However, deactivation of catalysts by coking and oxidation hinders the application of the reforming process. Dolomite-derived Ni-based catalysts with Fe additive, MgNi0.2Ca0.8−xFexO2±δ (x = 0–0.8, were successfully synthesized by the hydrothermal synthesis method, and then tested in auto-thermal reforming (ATR of acetic acid (AC. The MgNi0.2Ca0.5Fe0.3O2±δ catalyst performed a stable reactivity in ATR: the conversion of AC reached 100%, and the H2 yield remained stable around 2.6 mol-H2/mol-AC. The catalysts were characterized by X-ray diffraction (XRD, N2 physisorption, X-ray photoelectron spectra (XPS, H2-temperature-programmed reduction (TPR, inductively coupled plasma- atomic emission spectroscopy (ICP-AES and Thermogravimetry (TG; the results show that a periclase-like solid solution of Mg(Ni,FeO and lime were formed via the precursors of dolomite and hydrotalcite, and then transformed into Fe-rich Ni-Fe alloy with basic support of MgO-CaO after reduction. The stable Ni0 spices with basic support can explain the stability and resistance to coking during ATR of AC.

  19. Effect of Lime on Mechanical and Durability Properties of Blended Cement Based Concrete

    Science.gov (United States)

    Acharya, Prasanna Kumar; Patro, Sanjaya Kumar; Moharana, Narayana C.

    2016-06-01

    This work presents the results of experimental investigations performed to evaluate the effect of lime on mechanical and durability properties of concrete mixtures made with blended cement like Portland Slag Cement (PSC) and Portland Pozzolana Cement (PPC) with lime content of 0, 5, 7 and 10 %. Test result indicated that inclusion of hydraulic lime on replacement of cement up to 7 % increases compressive strength of concrete made with both PSC and PPC. Flexural strength increased with lime content. Highest flexural strength is reported at 7 % lime content for both PSC and PPC. Workability is observed to decrease with lime addition which could be compensated with introduction of super plasticizer. Acid and sulphate resistance increase slightly up to 7 % of lime addition and is found to decrease with further addition of lime. Lime addition up to 10 % does not affect the soundness of blended cements like PSC and PPC.

  20. Bacterially Induced Dolomite Formation in the Presence of Sulfate Ions under Aerobic Conditions

    Science.gov (United States)

    Sanchez-Roman, M.; McKenzie, J. A.; Vasconcelos, C.; Rivadeneyra, M.

    2005-12-01

    The origin of dolomite remains a long-standing enigma in sedimentary geology because, although thermodynamically favorable, precipitation of dolomite from modern seawater does not occur. Experiments conducted at elevated temperatures (200 oC) indicated that the presence of small concentrations of sulfate ions inhibits the transformation of calcite to dolomite [1]. Indeed, sulfate ions appeared to inhibit dolomite formation above 2 mM concentration (versus 28 mM in modern seawater). Recently, culture experiments have demonstrated that sulfate-reducing bacteria mediate the precipitation of dolomite at Earth surface conditions in the presence of sustained sulfate ion concentrations [2,3]. Additionally, in a number of modern hypersaline environments, dolomite forms from solutions with high sulfate ion concentrations (2 to 70 times seawater). These observations suggest that the experimentally observed sulfate-ion inhibition [1] may not apply to all ancient dolomite formation. Here, we report aerobic culture experiments conducted at low temperatures (25 and 35 oC) and variable sulfate ion concentrations (0, 0.5, 1 and 2 x seawater values) using moderately halophilic bacteria, Halomonas meridiana. After an incubation period of 15 days, experiments at 35 oC with variable sulfate ion concentrations (0, 0.5 x and seawater values) contained crystals of Ca-dolomite and stochiometric dolomite. The experiment at 35 oC with 2 x seawater sulfate ion concentration produced dolomite crystals after 20 days of incubation. In a parallel set of experiments at 25 oC, precipitation of dolomite was observed after 25 days of incubation in cultures with variable sulfate ion concentrations (0, 0.5 x and seawater values). In the culture with 2 x seawater sulfate ion concentration, dolomite crystals were observed after 30 days. Our study demonstrates that halophilic bacteria (or heterotrophic microorganisms), which do not require sulfate ions for metabolism, can mediate dolomite precipitation

  1. Reaction Sintering of Mexican Dolomite – Zircon Mixtures

    Directory of Open Access Journals (Sweden)

    Rodríguez-Galicia, J. L.

    2005-08-01

    Full Text Available The present work has been conducted aiming to develop additional phase [Ca3SiO5, Ca2SiO4 and/or Ca3Mg(SiO42]-bonded magnesia refractory materials via reaction sintering of dolomite-zircon mixtures, employing a Mexican dolomite containing an excess of 3 wt% of CaCO3. The study was based on phase equilibrium data extracted from the quaternary system CaO – MgO – SiO2 – ZrO2, to put it more precisely, base on the projection from the MgO-apex of the liquidus surface of the primary crystallization volume of MgO onto the opposite face of the above mentioned quaternary system. The refractory materials designed within this system were obtained by attrition milling, followed by cold isostatic pressing and high temperature reaction sintering. All initial and produced materials were characterized by ICP-AES, XRF, XRD, SEM-EDX, DTA and TG analyses. The results obtained indicated that reaction sintering of dolomite-zircon mixtures is an interesting route to produce MgO-CaZrO3-additional phase refractory materials.

    El propósito de este trabajo ha sido obtener materiales refractarios de magnesia, aglomerados con una fase adicional [Ca3SiO5, Ca2SiO4 y/o Ca3Mg(SiO42], mediante la sinterización reactiva de mezclas de dolomita-circón, empleando para ello una dolomita mexicana que contiene un exceso de 3% en peso de CaCO3. El estudio se basa en la información relativa al equilibrio de fases del sistema CaO – MgO – SiO2 – ZrO2. En concreto se usa la proyección, desde el vértice del MgO, de la superficie de liquidus del volumen de cristalización primaria de este, hacia la cara opuesta de sistema cuaternario. Los materiales refractarios diseñados se han obtenido por molienda de atrición, seguida de un prensado isostático en frío y sinterización reactiva a alta temperatura. Todos los materiales, iniciales y finales, han sido caracterizados mediante ICPAES, FRX, DRX, MEB-EDX, ATD y TG. Los resultados obtenidos indican que la sinterizaci

  2. Drilling Gas Hydrates on hydrate Ridge, Oregon continental margin

    Science.gov (United States)

    Trehu, A. M.; Bohrmann, G.; Leg 204 Science Party

    2002-12-01

    During Leg 204, we cored and logged 9 sites on the Oregon continental margin to determine the distribution and concentration of gas hydrates in an accretionary ridge and adjacent slope basin, investigate the mechanisms that transport methane and other gases into the gas hydrate stability zone (GHSZ), and obtain constraints on physical properties of hydrates in situ. A 3D seismic survey conducted in 2000 provided images of potential subsurface fluid conduits and indicated the position of the GHSZ throughout the survey region. After coring the first site, we acquired Logging-While-Drilling (LWD) data at all but one site to provide an overview of downhole physical properties. The LWD data confirmed the general position of key seismic stratigraphic horizons and yielded an initial estimate of hydrate concentration through the proxy of in situ electrical resistivity. These records proved to be of great value in planning subsequent coring. The second new hydrate proxy to be tested was infrared thermal imaging of cores on the catwalk as rapidly as possible after retrieval. The thermal images were used to identify hydrate samples and to estimate the distribution and texture of hydrate within the cores. Geochemical analyses of interstitial waters and of headspace and void gases provide additional information on the distribution and concentration of hydrate within the stability zone, the origin and pathway of fluids into and through the GHSZ, and the rates at which gas hydrate is forming. Bio- and lithostratigraphic description of cores, measurement of physical properties, and in situ pressure core sampling and thermal measurements complement the data set, providing ground-truth tests of inferred physical and sedimentological properties. Among the most interesting preliminary results are: 1) that gas hydrates are distributed through a broad depth range within the GHSZ and that different physical and chemical proxies for hydrate distribution and concentration give generally

  3. First evidence of lime burning in southern Scandinavia: lime kilns found at the royal residence on the west bank of Lake Tissø

    DEFF Research Database (Denmark)

    Henriksen, Peter Steen; Holst, Sandie

    2015-01-01

    In connection with investigations of the aristocratic residence at Tissø from the Viking Age, the earliest evidence so far of lime burning in Denmark has been excavated. The excavations unearthed traces of up to five lime kilns which were subsequently dated to the end of the ninth century....... This corresponds well with the dating of the erection of the hall in the third construction phase at Fugledegård. Finds of mud-and-wattle with whitewashing show that the lime was used to whitewash the halls at Tissø in both the Germanic Iron Age and the Viking Age. Analyses of lime from the lime kilns...

  4. Soybean root growth and crop yield in reponse to liming at the beginning of a no-tillage system

    Directory of Open Access Journals (Sweden)

    Edson Campanhola Bortoluzzi

    2014-02-01

    Full Text Available Analyzing the soil near crop roots may reveal limitations to growth and yield even in a no-tillage system. The purpose of the present study was to relate the chemical and physical properties of soil under a no-tillage system to soybean root growth and plant yield after five years of use of different types of limestone and forms of application. A clayey Oxisol received application of dolomitic and calcitic limestones and their 1:1 combination in two forms: surface application, maintained on the soil surface; and incorporated, applied on the surface and incorporated mechanically. Soil physical properties (resistance to mechanical penetration, soil bulk density and soil aggregation, soil chemical properties (pH, exchangeable cations, H+Al, and cation exchange capacity and plant parameters (root growth system, soybean grain yield, and oat dry matter production were evaluated five years after setting up the experiment. Incorporation of lime neutralized exchangeable Al up to a depth of 20 cm without affecting the soil physical properties. The soybean root system reached depths of 40 cm or more with incorporated limestone, increasing grain yield an average of 31 % in relation to surface application, which limited the effect of lime up to a depth of 5 cm and root growth up to 20 cm. It was concluded that incorporation of limestone at the beginning of a no-tillage system ensures a favorable environment for root growth and soybean yield, while this intervention does not show long-term effects on soil physical properties under no-tillage. This suggests that there is resilience in the physical properties evaluated.

  5. Rapid gas hydrate formation process

    Science.gov (United States)

    Brown, Thomas D.; Taylor, Charles E.; Unione, Alfred J.

    2013-01-15

    The disclosure provides a method and apparatus for forming gas hydrates from a two-phase mixture of water and a hydrate forming gas. The two-phase mixture is created in a mixing zone which may be wholly included within the body of a spray nozzle. The two-phase mixture is subsequently sprayed into a reaction zone, where the reaction zone is under pressure and temperature conditions suitable for formation of the gas hydrate. The reaction zone pressure is less than the mixing zone pressure so that expansion of the hydrate-forming gas in the mixture provides a degree of cooling by the Joule-Thompson effect and provides more intimate mixing between the water and the hydrate-forming gas. The result of the process is the formation of gas hydrates continuously and with a greatly reduced induction time. An apparatus for conduct of the method is further provided.

  6. Water transfer properties and shrinkage in lime-based rendering mortars

    Science.gov (United States)

    Arizzi, A.; Cultrone, G.

    2012-04-01

    Rendering is the practice of covering a wall or a building façade with one or more layers of mortar, with the main aim to protect the masonry structure against weathering. The render applied must show high flexibility, good adhesion and compatibility with the support (i.e. stone, brick) and, overall, it should be characterised by low water absorption and high water vapour permeability. Water (in the solid, liquid and vapour state) is one of the main factors that drive construction materials to deterioration. Therefore, to evaluate the quality and durability of a rendering mortar, thus ensuring its protective function in the masonry structure, it is fundamental to assess the behaviour of this mortar towards water. Mortars were elaborated with a calcitic dry hydrated lime, a calcareous aggregate, a pozzolan, a lightweight aggregate, a water-retaining agent and a plasticiser. Four types of lime mortars were prepared, in which the binder-to-aggregate ratios were 1:3, 1:4, 1:6 and 1:9 by weight, whilst the pozzolan was kept at 10% of the lime (by mass) and the total admixtures proportion was less than 2% of the total mass. The influence of the characteristics of mortars pore system on the amount of water absorbed and the kinetics of absorption was investigated by means of: free water absorption and drying; capillary uptake; water permeability; water vapour permeability. Interesting deductions can be made from the values of water and water vapour permeability found for mortars: the former increases exponentially with the sand volume of the mortar, whilst the latter increases almost exponentially with the initial water content added to the mortar mixes during their elaboration. However, the relationship obtained between porosity of mortars and permeability values is not really clear. This finding suggests that the permeability of a material cannot be estimated on the basis of its porosity as it can be made for the capillary uptake and free water absorption. Another

  7. Characterization of adsorption of aqueous arsenite and arsenate onto charred dolomite in microcolumn systems.

    Science.gov (United States)

    Salameh, Yousef; Al-Muhtaseb, Ala'a H; Mousa, Hasan; Walker, Gavin M; Ahmad, Mohammad N M

    2014-01-01

    In this work, the removal of arsenite, As(III), and arsenate, As(V), from aqueous solutions onto thermally processed dolomite (charred dolomite) via microcolumn was evaluated. The effects of mass of adsorbent (0.5-2 g), initial arsenic concentration (50-2000 ppb) and particle size (dolomite in a microcolumn were investigated. It was found that the adsorption of As(V) and As(III) onto charred dolomite exhibited a characteristic 'S' shape. The adsorption capacity increased as the initial arsenic concentration increased. A slow decrease in the column adsorption capacity was noted as the particle size increased from>0.335 to 0.710-2.00 mm. For the binary system, the experimental data show that the adsorption of As(V) and As(III) was independent of both ions in solution. The experimental data obtained from the adsorption process were successfully correlated with the Thomas Model and Bed Depth Service Time Model.

  8. An investigation on the catalytic capacity of dolomite in transesterification and the calculation of kinetic parameters.

    Science.gov (United States)

    Niu, Sheng-Li; Huo, Meng-Jia; Lu, Chun-Mei; Liu, Meng-Qi; Li, Hui

    2014-04-01

    The catalytic capacity of dolomite in transesterification was investigated and the kinetic parameters were calculated. The activated dolomites as transesterification catalyst were characterized by X-ray diffraction, nitrogen adsorption and desorption and Hammett indicator method, where the original dolomite was analyzed by thermogravimetric and X-ray fluorescence in advance. Its potential catalytic capacity was validated from aspects of the activated temperature and the reused property, where the reliability of the experimental system was also examined. Then, influences of the catalyst added amount, the mole ratio of methanol to oil, the transesterification temperature and the transesterification time on the catalytic capacity were investigated. Finally, kinetic parameters of the transesterification catalyzed by the activated dolomite were calculated.

  9. Secondary ferroan dolomite rhombs in oil reservoirs, Chadra Sands, Gialo field, Libya

    Energy Technology Data Exchange (ETDEWEB)

    Al-Shaieb, Z.; Shelton, J.W.

    1978-03-01

    Oil-productive, Oligocene Chadra sands in Gialo field, Libya, at depths of 600 to 750 m contain small dolomite rhombs. The rhombs are present as single crystals on detrital grains and as nonmosaic aggregates in pore space. The dolomite is calcium-rich and contains up to 10% iron but not measurable sodium or strontium. Total dissolved solids of produced interstitial water from the Chadra sand range from about 4,500 to 10,000 ppM. Introduction of fresh (meteoric) water into the Chadra sands, which were deposited in shallow-marine (shelf) environment, was responsible for formation of the dolomite rhombs. Iron in the dolomite rhombs was derived from alteration of galuconite.

  10. Dolomitization in a mixing zone of near-seawater composition, Late Pleistocene, northeastern Yucatan Peninsula

    Science.gov (United States)

    Ward, W. C.; Halley, Robert B.

    1985-01-01

    Patches of dolomite occur in cores of reefal limestone from the shallow subsurface on the northeastern coast of the Yucatan Peninsula. This limestone accumulated during an interglacial high stand of sea level about 200,000 years ago. Dolomitization was preceded by freshwater diagenesis, including precipitation of sparry calcite cement, stabilization of Mg-calcitic skeletal fragments, and partial dissolution of aragonitic components. This suggests a predolomitization lowering of sea level with the consequent freshening of pore water. The subsequent precipitation of dolomite indicates a return to high sea level with the consequent increase in Mg/Ca ratio of pore water. Dolomitization took place during a brief high stand of sea level, either shortly after deposition about 200,000 yr BP, r, more likely, about 125,000 yr BP.

  11. Hydration Characteristics of Tetracalcium Alumino-Ferrite Phase in the presence Calcium Carbonate

    Directory of Open Access Journals (Sweden)

    M. M. Radwan

    2011-12-01

    Full Text Available Tetracalcium alumino-ferrite phase (C4AF prepared from pure starting materials was employed for composing various mixes prepared of C4AF phase, CaSO4·2H2O, Ca(OH2 and CaCO3. The effect of replacing calcium sulphate (gypsum by calcium carbonate as a set retarder on the hydration behaviour of ferrite phase was studied. The mixes were hydrated for various periods and the hydration products were investigated using the appropriate techniques. The kinetics of hydration was studied by measuring the chemically-combined water as well as the combined lime contents. The mineralogical constitution was studied by using XRD, and DTA. The microstructure of some represented hydrated samples was investigated by scanning electron microscopy. Some interesting conclusions have been drawn. It was found that calcium carbonate reacts with tetracalcium alumino-ferrite phase (C4AF in the presence of hydrolime [Ca(OH2] to form carboferrite compounds which may coat the aluminate grains as ettringite does and this may probably regulate the setting time.

  12. Ab Initio Study of the Structure and Stability of High-Pressure Iron-Bearing Dolomite

    Science.gov (United States)

    Solomatova, N. V.; Asimow, P. D.

    2016-12-01

    Carbon is subducted into the mantle primarily in the form of metasomatically calcium-enriched basaltic rock, calcified serpentinites and carbonaceous ooze, all of which often contain dolomite. End-member CaMg(CO3)2 dolomite typically breaks down upon compression into two carbonates at 5-6 GPa in the temperature range of 800-1200 K [1]. However, high-pressure X-ray diffraction experiments have recently shown that the presence of iron may be sufficient to stabilize high-pressure dolomite over single-cation carbonates above 35 GPa [2,3]. The structure and equation of state of high-pressure dolomite phases have been debated, creating a need for theoretical calculations. Using density functional theory interfaced with a genetic algorithm that predicts crystal structures (USPEX), we have found a monoclinic phase with space group C2/c. The C2/c structure has a lower energy than previously reported dolomite structures at relevant pressures. It is possible that this phase is not achieved experimentally due to a large energy barrier and a correspondingly large required volume drop, resulting in the transformation to metastable dolomite II. We calculate the equation of state of trigonal dolomite, dolomite III and monoclinic C2/c dolomite to 80 GPa with 0 and 50 mol% CaFe(CO3)2 and compare their enthalpies to single-carbonate assemblages. Although end-member C2/c CaMg(CO3)2 dolomite is not stable relative to single-cation carbonates, C2/c CaMg0.5Fe0.5(CO3)2 is preferred over single-cation carbonates at high pressures. Thus, iron-bearing C2/c dolomite may be an important host phase for carbon in slabs subducted into the lower mantle. [1] Shirasaka, M., et al. (2002) American Mineralogist, 87, 922-930. [2] Mao, Z. et al. (2011) Geophysical Research Letters, 38. [3] Merlini, M. et al. (2012) Proceedings of the National Academy of Sciences, 109, 13509-13514.

  13. Thermal decomposition of dolomite under CO2: insights from TGA and in situ XRD analysis.

    Science.gov (United States)

    Valverde, Jose Manuel; Perejon, Antonio; Medina, Santiago; Perez-Maqueda, Luis A

    2015-11-28

    Thermal decomposition of dolomite in the presence of CO2 in a calcination environment is investigated by means of in situ X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The in situ XRD results suggest that dolomite decomposes directly at a temperature around 700 °C into MgO and CaO. Immediate carbonation of nascent CaO crystals leads to the formation of calcite as an intermediate product of decomposition. Subsequently, decarbonation of this poorly crystalline calcite occurs when the reaction is thermodynamically favorable and sufficiently fast at a temperature depending on the CO2 partial pressure in the calcination atmosphere. Decarbonation of this dolomitic calcite occurs at a lower temperature than limestone decarbonation due to the relatively low crystallinity of the former. Full decomposition of dolomite leads also to a relatively low crystalline CaO, which exhibits a high reactivity as compared to limestone derived CaO. Under CO2 capture conditions in the Calcium-Looping (CaL) process, MgO grains remain inert yet favor the carbonation reactivity of dolomitic CaO especially in the solid-state diffusion controlled phase. The fundamental mechanism that drives the crystallographic transformation of dolomite in the presence of CO2 is thus responsible for its fast calcination kinetics and the high carbonation reactivity of dolomitic CaO, which makes natural dolomite a potentially advantageous alternative to limestone for CO2 capture in the CaL technology as well as SO2in situ removal in oxy-combustion fluidized bed reactors.

  14. Can Mn–S redox cycling drive sedimentary dolomite formation? A hypothesis

    Energy Technology Data Exchange (ETDEWEB)

    Petrash, Daniel A.; Lalonde, Stefan V.; González-Arismendi, Gabriela; Gordon, Robert A.; Méndez, José A.; Gingras, Murray K.; Konhauser, Kurt O. (CLS); (UCV-Venezuela); (CNRS-UMR); (Alberta)

    2016-06-10

    The formation of dolomite in modern peritidal environments is linked to the degradation of buried microbial mats, with complexation of Ca and Mg by extracellular polymeric substances (EPSs) and alkalinity generation through organic carbon respiration facilitating the nucleation of dolomite precursors. In the past two decades, microbial sulfate reduction, methanogenesis, and methanotrophy have all been considered as potential drivers of the nucleation process, but it remains unclear why dolomite formation could not also occur in suboxic sediments where abundant alkalinity is produced by processes linked to Mn(IV) and/or Fe(III) reduction coupled with the diffusion and reoxidation of reduced sulfur species. Here we report the interstitial occurrence of spheroidal aggregates of nanometer-scale Ca-rich dolomite rhombohedra within suboxic sediments associated with remnant microbial mats that developed in the peritidal zone of the Archipelago Los Roques, Venezuela. Multiple analytical tools, including EPMA, ICP-MS, synchrotron-based XRF and XRD, and spatially resolved XANES microanalyses, show that the dolomite-cemented interval exhibits depleted bulk iron concentrations, but is interstitially enriched in Mn and elemental sulfur (S⁰). Manganese occurs in several oxidation states, indicating that the dolomite-cemented interval was the locus of complex biological redox transformations characterized by coupled Mn and S cycling. The tight correspondence between sedimentary Mn and MgCO₃ concentrations further hints at a direct role for Mn during dolomitization. While additional studies are required to confirm its relevance in natural settings, we propose a model by which coupled Mn–S redox cycling may promote alkalinity generation and thus dolomite formation in manner similar to, or even more efficiently, than bacterial sulfate reduction alone.

  15. Evaluating formation fluid models and calibrations using clumped isotope paleothermometry on Bahamian dolomites

    Science.gov (United States)

    Murray, Sean T.; Swart, Peter K.

    2017-06-01

    The use of stable oxygen isotopes to understand the mechanisms of dolomite formation has been hampered by the inability to precipitate well-ordered dolomite under normal Earth surface conditions. Several studies have attempted to address this problem, either by precipitating high-temperature ordered dolomites and extrapolating the data to low temperatures or by using more disordered very-high Mg-calcites as a proxy for low temperature dolomites. The result is eight equations that disagree significantly from each other (by as much as ∼3.6‰ in the δ18O value of the precipitating fluid at 25 °C), and produce differences which can greatly affect the interpretation of the formation mechanisms for low temperature dolomites. However, by combining the recently developed clumped-isotope paleothermometer, an independent isotopic measurement (∆47) that directly relates to the temperature of formation, to Late Miocene to Pleistocene aged dolomites from the Bahamas with a well-constrained thermal and fluid history, we have attempted to narrow down the viable equations used to interpret the δ18O values of dolomites. The clumped-isotope temperatures measured on the Bahamian dolomites (16-37 °C) agrees with the range of temperatures expected in the Bahamas. Pairing these temperatures with geological and mineralogical arguments, we favor the equation suggested by Matthews and Katz (1977), as it is the only one that produces realistic δ18O fluid values across the range of clumped-isotope temperatures. Both the clumped-isotope temperatures and δ18O values of the precipitating fluid show a strong positive covariance that we have interpreted as reflecting the mixing of surface brines that have undergone varying amounts of evaporation and normal seawater. The different mechanisms driving these fluids included formation by normal marine seawater driven by the compensatory flow of the mixing zone, bank wide Kohout convection, and evaporative brine reflux.

  16. Numerical modelling of geothermal and reflux circulation in Enewetak Atoll: Implications for dolomitization

    Science.gov (United States)

    Jones, G.; Whitaker, F.; Smart, P.; Sanford, W.

    2000-01-01

    Two types of regional-scale seawater circulation have been proposed to explain the formation of Enewetak Atoll dolomites: geothermal and reflux circulation. We have used a finite element groundwater flow model to examine the pattern, magnitude and dynamic interaction of these two different circulation mechanisms in Enewetak Atoll. Geothermal circulation is concentrated around the atoll-margin whereas refluxing mesosaline brines flow from the atoll interior towards the margin to restrict and eventually shut off geothermal circulation. Refluxing brines of 36-80??? can account for the salinity signature recorded in dolomite fluid inclusions. Distributions of fluid flux and Mg mass-balance calculations suggest that both geothermal and reflux circulation mechanisms could account for the observed distribution of dolomite in Enewetak Atoll. Furthermore, the atoll interior may be extensively dolomitized as observed in other atolls. (C) 2000 Elsevier Science B.V. All rights reserved.Two types of regional-scale seawater circulation have been proposed to explain the formation of Enewetak Atoll dolomites: geothermal and reflux circulation. We have used a finite element groundwater flow model to examine the pattern, magnitude and dynamic interaction of these two different circulation mechanisms in Enewetak Atoll. Geothermal circulation is concentrated around the atoll-margin whereas refluxing mesosaline brines flow from the atoll interior towards the margin to restrict and eventually shut off geothermal circulation. Refluxing brines of 36-80 per mil can account for the salinity signature recorded in dolomite fluid inclusions. Distributions of fluid flux and Mg mass-balance calculations suggest that both geothermal and reflux circulation mechanisms could account for the observed distribution of dolomite in Enewetak Atoll. Furthermore, the atoll interior may be extensively dolomitized as observed in other atolls.

  17. Experimental investigation and constitutive model for lime mudstone.

    Science.gov (United States)

    Wang, Junbao; Liu, Xinrong; Zhao, Baoyun; Song, Zhanping; Lai, Jinxing

    2016-01-01

    In order to investigate the mechanical properties of lime mudstone, conventional triaxial compression tests under different confining pressures (0, 5, 15 and 20 MPa) are performed on lime mudstone samples. The test results show that, from the overall perspective of variation law, the axial peak stress, axial peak strain and elastic modulus of lime mudstone tend to gradually increase with increasing confining pressure. In the range of tested confining pressure, the variations in axial peak stress and elastic modulus with confining pressure can be described with linear functions; while the variation in axial peak strain with confining pressure can be reflected with a power function. To describe the axial stress-strain behavior in failure process of lime mudstone, a new constitutive model is proposed, with the model characteristics analyzed and the parameter determination method put forward. Compared with Wang' model, only one parameter n is added to the new model. The comparison of predicted curves from the model and test data indicates that the new model can preferably simulate the strain softening property of lime mudstone and the axial stress-strain response in rock failure process.

  18. Liming of acid soils in Osijek-Baranja county

    Directory of Open Access Journals (Sweden)

    Dolijanović Željko

    2011-01-01

    Full Text Available The negative trend of soil degradation process increases with intensive agricultural production. Therefore, there is a need for soil conditioning like liming, humification, fertilization, etc. to improve soil quality. One of the major problems that occur on agricultural soils of Croatia is acidification. A downward trend of soil pH is mainly present in soils of poor structure with intensive agricultural production. In agricultural practice liming often needs to rely only on the pH value, without determining the hydrolytic acidity, CEC or soil texture. Due to the above mentioned facts, calculation of liming for Osijek-Baranja County was conducted with the help of ALRxp calculator, which takes CEC, soil pH in KCl, hydrolytic acidity, bulk density of soil, soil textural class and depth of the plow layer to 30 cm into account. Low soil pH values have a great influence on soil suitability for crops as well as on the deficit of calcium and magnesium. All of these lead to the degradation of soil structure, and can even lead to disturbances of plant nutrition in some production areas. On such soils, liming would be imperatively required, but with caution because an excessive intake of lime materials, especially without the necessary analysis, causes a decline in organic matter and reduces accessibility for plant uptake of microelements.

  19. Long term trends of fish after liming of Swedish streams and lakes

    Science.gov (United States)

    Holmgren, Kerstin; Degerman, Erik; Petersson, Erik; Bergquist, Björn

    2016-12-01

    Thousands of Swedish acidified lakes and streams have been regularly limed for about 30 years. Standard sampling of fish assemblages in lakes and streams was an important part of monitoring the trends after liming, i.e. sampling with multi-mesh gillnets in lakes (EN 14757) and electrofishing in streams (EN 14011). Monitoring data are nationally managed, in the National Register of Survey test-fishing and the Swedish Electrofishing Register. We evaluated long-term data from 1029 electrofishing sites in limed streams and gillnet sampling in 750 limed lakes, along with reference data from 195 stream sites and 101 lakes with no upstream liming in their catchments. The median year of first liming was 1986 for both streams and lakes. The proportion of limed stream sites with no fish clearly decreased with time, mean species richness and proportion of sites with brown trout (Salmo trutta) recruits increased. There were no consistent trends in fish occurrence or species richness at non-limed sites, but occurrence of brown trout recruits also increased in acid as well as neutral reference streams. Abundance of brown trout, perch (Perca fluviatilis) and roach (Rutilus rutilus) increased significantly more at limed sites than at non-limed reference sites sampled before and after 1986. The mean species richness did not change consistently in limed lakes, but decreased in low alkalinity reference lakes, and fish abundance decreased significantly in limed as well as in non-limed lakes.

  20. The relationship between dolomitization and organic matter occurrence in Lower Paleozoic carbonate in the Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Based on observations on the core and surface sections of Lower Paleozoic carbonate in the Ordos Basin, petrography research and measurements of TOC, TOS , Ro, XRD, and comparative study with dolomite in modern Coorong Lake, it has been revealed that: (i)dolomitization may occur in micrite limestone, gypsum-halite and argillaceous sandstone, and it can be divided into three types: sedimentary penecontemporaneous-early diagenesis, late diagenesis of deep burial and catagenesis of uplift period. However, the crystal cell of the second type less than 35 μ m in size is most closely associated with gas pool; (ii) the highest content of organic matter (OM) is produced in samples from the argillic dolomite which may be formed by argillaceous fluid through gypsum-halite; (iii) in the evolution process from penecontemporaneous dolomite into stoichiometric dolomite, the crystal order of dolomite and the porosity of its host rock tend to increase, which is favorable to the formation of an available migration network. When the power of the fluid is high enough, the network is mainly favorable to the migration and transport of heat, but when the power of the fluid goes down, the network system is favorable, due to its large space, to OM deposition in it.

  1. Quantitative lateral force microscopy study of the dolomite (104)-water interface.

    Science.gov (United States)

    Higgins, Steven R; Hu, Xiaoming; Fenter, Paul

    2007-08-14

    The friction and lateral stiffness of the contact between an atomic force microscopy (AFM) probe tip and an atomically flat dolomite (104) surface were investigated in contact with two aqueous solutions that were in equilibrium and supersaturated with respect to dolomite, respectively. The two aqueous solutions yielded negligible differences in friction at the native dolomite-water interface. However, the growth of a Ca-rich film from the supersaturated solution, revealed by X-ray reflectivity measurements, altered the probe-dolomite contact region sufficiently to observe distinct friction forces on the native dolomite and the film-covered surface regions. Quantitative friction-load relationships demonstrated three physically distinct load regimes for applied loads up to 200 nN. Similar friction forces were observed on both surfaces below 50 nN load and above 100 nN load. The friction forces on the two surfaces diverged at intermediate loads. Quantitative measurements of dynamic friction forces at low load were consistent with the estimated energy necessary to dehydrate the surface ions, whereas differences in mechanical properties of the Ca-rich film and dolomite surfaces were evidently important above 50 nN load. Attempts to fit the quantitative stiffness-load data using a Hertzian contact mechanical model based on bulk material properties yielded physically unrealistic fitting coefficients, suggesting that the interfacial contact region must be explicitly considered in describing the static and dynamic contact mechanics of this and similar systems.

  2. Performance of thermally activated dolomite for the treatment of Ni and Zn in contaminated neutral drainage.

    Science.gov (United States)

    Calugaru, Iuliana Laura; Neculita, Carmen Mihaela; Genty, Thomas; Bussière, Bruno; Potvin, Robin

    2016-06-05

    Intensive research is ongoing for developing low-cost and highly efficient materials in metal removal from contaminated effluents. The present study evaluated dolomite [CaMg(CO3)2], both raw and modified by thermal activation (charring), for Ni and Zn treatment in contaminated neutral drainage (CND). Batch adsorption testing (equilibrium and kinetics) were conducted at pH 6, to evaluate the performance of initial vs. modified dolomite, and to assess potential mechanisms of metal removal. Charring of dolomite led to a rigid and porous material, mainly consisting of CaCO3 and MgO, which showed a sorption capacity increased sevenfold for Zn and doubled for Ni, relative to the raw material. In addition, Freundlich model best described the sorption of the both metals by dolomite, whereas the Langmuir model best described their sorption on charred dolomite. Plausible mechanisms of metal removal include cation exchange, surface precipitation and sorption processes, with carbonate ions and magnesium oxides acting as active centers. Based on these results, charred dolomite seems a promising option for the efficient treatment of Ni and Zn in CND.

  3. Adsorptive removal of phosphate from aqueous solutions using raw and calcinated dolomite.

    Science.gov (United States)

    Karaca, S; Gürses, A; Ejder, M; Açikyildiz, M

    2006-02-06

    This study explored the feasibility of utilizing raw and calcinated dolomite under CO2 atmosphere for phosphate removal in laboratory experiments. The experimental work emphasized the evaluation of phosphate adsorption characteristics of this adsorbent material. Studies were conducted to delineate the effect of contact time, initial phosphate concentration, temperature, pH, stirring speed, adsorbent dose and calcination temperature. Phosphate removal decreased with increasing temperature and slightly increased with increasing of pH. The observed decrease in the adsorption capacity with increase of the temperature from 20 to 40 and to 60 degrees C indicates that the low temperatures favor the phosphate removal by adsorption onto dolomite. Phosphate removal was seen to decrease with increasing calcination temperature due to the structural changes occurring in the structure and pore size distribution of dolomite samples during calcination. The experimental data obtained were applied to the Freundlich, Langmuir, BET, Halsey, Harkins-Jura, Smith and Henderson isotherm equations to test the fit of these equations to raw and calcinated dolomite samples. By considering the experimental results and adsorption models applied in this study, it can be concluded that adsorption of phosphate occurs predominantly through physical interactions, and the dolomite sample has a heteroporous structure. The large values of the constants for Henderson equation and the high value of y(m) obtained from BET equation indicate the microporous structure is more stable in raw and calcinated dolomite samples.

  4. PHOSPHORUS REMOVAL IN A VERTICAL FLOW CONSTRUCTED WETLAND USING DOLOMITE POWDER AND CHIPPINGS AS FILTER MEDIA

    Directory of Open Access Journals (Sweden)

    Gražina Žibienė

    2015-12-01

    Full Text Available Different kinds of natural and artificial filter media are able to retain phosphorus in the constructed wetlands. Due to the fact that the constructed wetland needs huge amounts of the filter media, it is very important to find locally available material which distinguishes itself by its ability to retain phosphorus. The materials found in Lithuania were considered and dolomite was chosen. Two dolomite fractions, dolomite powder (1–2 mm and dolomite chippings (2–5 mm, and sand media were used in the laboratory- scale installed for the comparative experiments. The laboratory-scale with dolomite as the filter media was on average by 21% more efficient in total phosphorus removal in comparison with the sand media. Based on the laboratory research pilot–scale vertical flow constructed wetland of 160 m2 was installed and planted with reed Phragmites australis. The dolomite chippings as filter media were chosen in order to avoid the danger of the clogging of constructed wetland. Efficiency of total phosphorus removal in the pilot-scale vertical flow constructed wetland was on average 95.7%, phosphates removal – 94.8% within one year.

  5. DOLOMITE THERMAL-DECOMPOSITION MACROKINETIC MODELS FOR EVALUATION OF THE GASGENERATORS SORBENT SYSTEMS

    Directory of Open Access Journals (Sweden)

    K. V. Dobrego

    2015-01-01

    Full Text Available Employing dolomite in the capacity of a sorbent for generator gas purification is of considerable interest nowadays, as it is the impurity of generator gas that causes the major problem for creating cheep and effective co-generator plants. Designing gas purification systems employs simple but physically adequate macrokinetic models of dolomite thermal decomposition.  The  paper  analyzes  peculiarities  of  several  contemporaneous  models  of  dolomite and calcite thermal decomposition and infers on reasonable practicality for creating compact engineering dolomite-decomposition macrokinetic models and universal techniques of these models parameter reconstruction for specific dolomite samples. Such technics can be founded on thermogravimetric data and standard approximation error minimizing algorithms.The author assumes that CO2  evacuation from the reaction zone within the particle may proceed by diffusion mechanism and/or by the Darcy filtration and indicates that functional dependence of the thermal-decomposition rate from the particle sizes and the temperature differs for the specified mechanisms. The paper formulates four macrokinetic models whose correspondence verification is grounded on the experimental data. The author concludes that further work in this direction should proceed with the dolomite samples investigation and selecting the best approximation model describing experimental data in wide range of temperatures, warming up rates and the particle sizes.

  6. Study on Technological Characteristic of Process of Calcining and Decomposing Dolomite Ore%白云石煅烧离解过程的工艺特性研究

    Institute of Scientific and Technical Information of China (English)

    蒋述兴

    2011-01-01

    对不同温度下煅烧成的苛性白云石进行了X射线粉晶分析,结合热分析结果,得出在750~800℃温度下煅烧成的苛性白云石镁质胶凝材料,其中的Mgo水化活性较大.在煅烧白云石的过程中,是结晶--化学反应为限制步骤,因此,要尽可能创设条件,加速化学反应的进行,并要尽可能控制好煅烧时间,以便抑制氧化镁的完全结晶.另外,分析计算了在利用临桂县白云石生产苛性白云石镁质胶凝材料时,不同粒度(5~250mm的多种粒度)的块状白云石在不同温度下完全离解所需要的煅烧时间.%The work of the XRD of the caustic dolomite prepared by different calcining temperatures had been done.According to the results of the XRD and DTA of the dolomite in the atmosphere of the CO2, we reached a conclusion that the MgO of the magnesia cementitious material of the caustic dolomite calcined at the temperature condition from 750℃ to 800℃ possessed larger hydration activity. In the process of calcining and decomposing the dolomite ore, the restrictive step was the crystallization and chemical reaction. The condition to quicken the chemical reaction should be consequently created as far as possible, and the calcining time should be controlled as far as possible to restrain the complete crystallization of the MgO in the caustic dolomite. In addition,the required calcining times to fully decompose the MgCOj in the big lump dolomites which were the paticles from 5mm to 250 mm had been obtained by the methods of the experiments,analysis and computations.

  7. Kinetics of lime/bentonite pozzolanic reactions at 20 and 50 °C: Batch tests and modeling

    Energy Technology Data Exchange (ETDEWEB)

    De Windt, Laurent, E-mail: laurent.dewindt@mines-paristech.fr [Mines-ParisTech (Ecole des Mines de Paris), Centre de Géosciences, 35 Rue St-Honoré, 77305 Fontainebleau Cedex (France); Deneele, Dimitri [LUNAM, IFSTTAR, Institut Français des Sciences et des Technologies des Transports, de l' Aménagement et des Réseaux, BP 4129, route de Bouaye, 44332 Bouguenais (France); Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, CNRS, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3 (France); Maubec, Nicolas [LUNAM, IFSTTAR, Institut Français des Sciences et des Technologies des Transports, de l' Aménagement et des Réseaux, BP 4129, route de Bouaye, 44332 Bouguenais (France)

    2014-05-01

    The effects of duration (1–100 days) and temperature (20 and 50 °C) were assessed from batch tests for Ca-bentonite mixed with 10 wt.% lime. The pozzolanic processes were monitored over time by {sup 29}Si NMR (Cement Concr. Res. 42, 2012), TGA-DTA, XRD and chemical analysis. Modeling considered kinetics and thermodynamics of mineralogical transformations and cation exchange. Kinetic laws were dependent on pH and temperature (Arrhenius energy). Lime hydration occurs within hours, modifying the bentonite exchangeable population and increasing the pH. These alkaline conditions initiate the pozzolanic reactions in a second stage. The rate-limiting step is the dissolution kinetics of the bentonite minerals, i.e. a relatively fast and total consumption of cristobalite in parallel to a long-term slower dissolution of montmorillonite. First C–S–H and then C–A–S–H are formed consequently. Temperature speeds up the pozzolanic reaction kinetics by a factor 5 from 20 to 50 °C, corresponding to an apparent activation energy of 40–50 kJ/mol.

  8. Influence of water-repellent treatment on the properties lime and lime pozzolan mortars

    Directory of Open Access Journals (Sweden)

    Fortes Revilla, C.

    2001-06-01

    Full Text Available The influence that water-repellent products can have on physical and micro-structural properties of lime mortars, and lime plus pozzolan mortars has been studied. Three water repellent products have been used. Mixes of the previously mentioned three water repellents plus a biocide product were also applied. Treatments make the total porosity and saturation coefficient of both mortars to decrease, while colorimetric coordinates bear little alteration. All treatments with water repellent products provided mortars with a hydrophobic property index close to 100%. Durability of such mortars has been also studied: salt crystallization test, frost-thaw and dry-wet cycles, as well as ultraviolet radiation test were carried out. Relationship between mortars behavior and their porosity and saturation coefficient were found.

    En el presente trabajo se ha estudiado la influencia de la aplicación de productos hidrofugantes a morteros de cal y morteros de cal y puzolana sobre sus propiedades físicas y microestructurales. Se han estudiado tres productos hidrofugantes. También han sido estudiados dichos productos junto con un biocida. La porosidad total y el coeficiente de saturación de ambos tipos de morteros se ve reducido por el efecto de los tratamientos mientras que las coordenadas colorimétricas se ven poco alteradas. Todos los tratamientos confieren un índice de hidrofobicidad a los morteros próximo al 100%. Asimismo, también se ha estudiado la durabilidad de dichos morteros frente a la cristalización de sales, hielo-deshielo, los ciclos de humedad-sequedad y radiaciones ultravioleta. Se relaciona el comportamiento de los morteros con su porosidad y el coeficiente de saturación.

  9. EVALUATION OF BIOAEROSOL COMPONENTS, GENERATION FACTORS, AND AIRBORNE TRANSPORT ASSOCIATED WITH LIME TREATMENT OF CONTAMINATED SEDIMENT

    Science.gov (United States)

    Lime treatment has been used in contaminated sediment management activities for many purposes such as dewatering, improvement of physical properties, and reducing contaminant mobility. Exothermic volatilization of volatile organic compounds from lime-treated sediment is well kno...

  10. REMOVAL OF BERYLLIUM FROM DRINKING WATER BY CHEMICAL COAGULATION AND LIME SOFTENING

    Science.gov (United States)

    The effectiveness of conventional drinking water treatment and lime softening was evaluated for beryllium removal from two drinking water sources. ar test studies were conducted to determine how common coagulants (aluminum sulfate and ferric chloride and lime softening performed ...

  11. Hydration and physical performance.

    Science.gov (United States)

    Murray, Bob

    2007-10-01

    There is a rich scientific literature regarding hydration status and physical function that began in the late 1800s, although the relationship was likely apparent centuries before that. A decrease in body water from normal levels (often referred to as dehydration or hypohydration) provokes changes in cardiovascular, thermoregulatory, metabolic, and central nervous function that become increasingly greater as dehydration worsens. Similarly, performance impairment often reported with modest dehydration (e.g., -2% body mass) is also exacerbated by greater fluid loss. Dehydration during physical activity in the heat provokes greater performance decrements than similar activity in cooler conditions, a difference thought to be due, at least in part, to greater cardiovascular and thermoregulatory strain associated with heat exposure. There is little doubt that performance during prolonged, continuous exercise in the heat is impaired by levels of dehydration >or= -2% body mass, and there is some evidence that lower levels of dehydration can also impair performance even during relatively short-duration, intermittent exercise. Although additional research is needed to more fully understand low-level dehydration's effects on physical performance, one can generalize that when performance is at stake, it is better to be well-hydrated than dehydrated. This generalization holds true in the occupational, military, and sports settings.

  12. Liming Poultry Manures to Kill Pathogens and Decrease Soluble Phosphorus

    Energy Technology Data Exchange (ETDEWEB)

    Maguire,R.; Hesterberg, D.; Gernat, A.; Anderson, K.; Wineland, M.; Grimes, J.

    2006-01-01

    Received for publication September 9, 2005. Stabilizing phosphorus (P) in poultry waste to reduce P losses from manured soils is important to protect surface waters, while pathogens in manures are an emerging issue. This study was conducted to evaluate CaO and Ca(OH){sub 2} for killing manure bacterial populations (pathogens) and stabilizing P in poultry wastes and to investigate the influence on soils following amendment with the treated wastes. Layer manure and broiler litter varying in moisture content were treated with CaO and Ca(OH){sub 2} at rates of 2.5, 5, 10, and 15% by weight. All treated wastes were analyzed for microbial plate counts, pH, and water-soluble phosphorus (WSP), while a few selected layer manures were analyzed by phosphorus X-ray absorption near edge structure (XANES). A loamy sand and a silt loam were amended with broiler litter and layer manure treated with CaO at rates of 0, 2.5, 5, 10, and 15% and soil WSP and pH were measured at times 1, 8, and 29 d. Liming reduced bacterial populations, with greater rates of lime leading to greater reductions; for example 10% CaO applied to 20% solids broiler litter reduced the plate counts from 793 000 to 6500 mL{sup -1}. Liming also reduced the WSP in the manures by over 90% in all cases where at least 10% CaO was added. Liming the manures also reduced WSP in soils immediately following application and raised soil pH. The liming process used successfully reduced plate counts and concerns about P losses in runoff following land application of these limed products due to decreased WSP.

  13. Ductile flow of methane hydrate

    Science.gov (United States)

    Durham, W.B.; Stern, L.A.; Kirby, S.H.

    2003-01-01

    Compressional creep tests (i.e., constant applied stress) conducted on pure, polycrystalline methane hydrate over the temperature range 260-287 K and confining pressures of 50-100 MPa show this material to be extraordinarily strong compared to other icy compounds. The contrast with hexagonal water ice, sometimes used as a proxy for gas hydrate properties, is impressive: over the thermal range where both are solid, methane hydrate is as much as 40 times stronger than ice at a given strain rate. The specific mechanical response of naturally occurring methane hydrate in sediments to environmental changes is expected to be dependent on the distribution of the hydrate phase within the formation - whether arranged structurally between and (or) cementing sediments grains versus passively in pore space within a sediment framework. If hydrate is in the former mode, the very high strength of methane hydrate implies a significantly greater strain-energy release upon decomposition and subsequent failure of hydrate-cemented formations than previously expected.

  14. Produtividade e qualidade fisiológica de sementes de aveia preta em função da calagem superficial em plantio direto = Black oat yield and seed physiologic quality under superficial lime application in no tillage system

    Directory of Open Access Journals (Sweden)

    Tiago Roque Benetoli da Silva

    2006-04-01

    Full Text Available Com o objetivo de avaliar a produtividade e a qualidade fisiológica de sementes de aveia preta em razão da aplicação superficial de calcário em plantio direto, foi realizado um experimento em Botucatu, Estado de São Paulo, sob condições de sequeiro. O delineamento experimental foi o de blocos casualizados, com quatro repetições, em que os tratamentos foram constituídos por aplicação superficial de doses de calcário dolomítico (D0 = zero – sem aplicação de calcário; D1 = 1,8 t ha-1 – quantidade de calcário para elevar a saturação por bases a 54%; D2 = 3,6 t ha-1 – quantidade de calcário para elevar a saturação por bases a 68% e D3 = 5,4 t ha-1 – quantidade de calcário para elevar a saturação por bases a 80%, realizada em outubro de 2002. A cultura da aveia preta, cultivar Comum, foi semeada em abril de 2004, no segundo ano após a rotação milheto (primavera, feijão (verão e aveia preta (outono e inverno. Com os resultados obtidos, observou-se ganho de produtividade com a aplicação superficial de calcário, porém sem influenciar a qualidade fisiológica das sementes de aveia preta.The experiment carried out in Botucatu, São Paulo State, Brazil, in dry conditions, aiming to evaluate the yield and physiologic quality of black oat seeds, under superficial liming in no tillage system. A randomized complete block design was used, with four replications. The treatments were superficial application of different dolomitic lime rates (R0 = zero – without lime; R1 = 1.8 t ha-1 – lime to increase the base saturation at 54%; R2 = 3.6 t ha-1 – lime to increase the base saturation at 68%, and R3 = 5.4 t ha-1 – lime to increase the base saturation at 80%, in October 2002. The blackoat Common cultivar was sowed in April 2004, in second year, after the crop rotation of millet (spring, common bean (summer, black oat (autumn/winter. The results showed that the black oat physiologic quality seed was not affected by

  15. The influence of solution composition and grain boundaries on the replacement of calcite by dolomite

    Science.gov (United States)

    Moraila Martinez, Teresita de Jesus; Putnis, Christine V.; Putnis, Andrew

    2016-04-01

    Dolomite formation is a mineral replacement reaction that affects extensive rock volumes and comprises a large fraction of oil and gas reservoirs [1,2]. The most accepted hypothesis is the 'dolomitization' of limestone by Mg-rich fluids [3]. The objective of this research is to study the replacement mechanism of calcite by dolomite, the role of grain boundaries, highlighted by Etschmann et al. (2014), and the possible influence of solutions in dolomite formation under the presence of ions that are normally in crustal aqueous fluids. To accomplish this purpose, we performed hydrothermal experiments using Carrara marble cubes of ~1.5 mm size and 7-9 mg weight as starting material, reacted with 1M (Mg,Ca)Cl2 aqueous solutions, with Mg/Ca ratios of 3 and 5 at 200°C, for different reaction times. Additional experiments were performed adding 1mM of Na2SO4, NaCl or NaF to the previous solutions. After the reaction, the product phases were identified using Raman spectroscopy, X-Ray powder diffraction (XRD), electron microprobe analysis (EMPA), and the textural evolution was studied by scanning electron microscopy (SEM). Samples reacted with aqueous solutions resulted in the replacements of the calcite rock into magnesite and dolomite. The amount and type of reaction strongly depends on the Mg/Ca ratio. Samples reacted with a Mg/Ca ratio of 5 resulted in an almost complete replacement reaction and more favorable for magnesite formation than for dolomite. When the Mg/Ca ratio was 3 dolomite formed but the replacement was located in the core of the sample. We show that grain boundaries are very important for the infiltration of solution and the progress of a replacement reaction, acting as fluid pathways. Solution composition controls the nature of the replacement product. Acknowledgment: This work is funded within a Marie Curie EU Initial Training Network- CO2-React. 1. Etschmann B., Brugger J., Pearce M.A., Ta C., Brautigan D., Jung M., Pring A. (2014). Grain boundaries as

  16. Some thermodynamical aspects of protein hydration water

    Energy Technology Data Exchange (ETDEWEB)

    Mallamace, Francesco, E-mail: francesco.mallamace@unime.it [Dipartimento di Fisica e Scienze della Terra, Università di Messina and CNISM, I-98168 Messina (Italy); Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Center for Polymer Studies and Department of Physics, Boston University, Boston, Massachusetts 02215 (United States); Corsaro, Carmelo [Dipartimento di Fisica e Scienze della Terra, Università di Messina and CNISM, I-98168 Messina (Italy); CNR-IPCF, Viale F. Stagno D’Alcontres 37, I-98158 Messina (Italy); Mallamace, Domenico [Dipartimento SASTAS, Università di Messina, I-98166 Messina (Italy); Vasi, Sebastiano [Dipartimento di Fisica e Scienze della Terra, Università di Messina and CNISM, I-98168 Messina (Italy); Vasi, Cirino [CNR-IPCF, Viale F. Stagno D’Alcontres 37, I-98158 Messina (Italy); Stanley, H. Eugene [Center for Polymer Studies and Department of Physics, Boston University, Boston, Massachusetts 02215 (United States); Chen, Sow-Hsin [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-06-07

    We study by means of nuclear magnetic resonance the self-diffusion of protein hydration water at different hydration levels across a large temperature range that includes the deeply supercooled regime. Starting with a single hydration shell (h = 0.3), we consider different hydrations up to h = 0.65. Our experimental evidence indicates that two phenomena play a significant role in the dynamics of protein hydration water: (i) the measured fragile-to-strong dynamic crossover temperature is unaffected by the hydration level and (ii) the first hydration shell remains liquid at all hydrations, even at the lowest temperature.

  17. DNA markers provide insight about common lime in historicalplantings

    DEFF Research Database (Denmark)

    Hansen, Ole Kim; Thomsen, Pernille; Rasmussen, Christine Waage

    2014-01-01

    nurseries in the Netherlands and Germany. It also provides evidence that it is possible to obtain the same genetic material as originally planted when common lime trees are to be replaced in historical plantings. Furthermore, the utility of DNA markers in the management of plant material in parks......As part of the restoration process of an avenue of common lime (Tilia × europaea) from 1760 in the Royal Danish Gardens, all remaining trees were genotyped with DNA markers before they were felled. As such, information about the nature of the plant material (clonal versus non-clonal) and mode...

  18. Glass-Forming Ability of Soda Lime Borate Liquids

    DEFF Research Database (Denmark)

    Zheng, Qiuju; Mauro, J.C.; Smedskjær, Morten Mattrup

    2012-01-01

    We investigate the composition dependence of glass-forming ability (GFA) of a series of iron-containing soda lime borate liquids by substituting Na2O for B2O3. We have characterized GFA by measuring the glass stability against crystallization using a differential scanning calorimeter (DSC......). The results show that the GFA decreases when substituting Na2O for B2O3. Moreover, we find that there is no direct link between the kinetic fragility and GFA for the soda lime borate series studied herein. We have also discovered and clarified a striking thermal history dependence of the glass stability...

  19. Ground-water flow modeling of the Culebra dolomite

    Energy Technology Data Exchange (ETDEWEB)

    LaVenue, A.M.; Cauffman, T.L.; Pickens, J.F. (INTERA, Inc., Austin, TX (USA))

    1990-10-01

    This hydrogeologic modeling study has been performed as part of the regional hydrologic characterization of the Waste Isolation Pilot Plant (WIPP) site in southeastern New Mexico. The study has produced an estimation of the transmissivity and Darcy-velocity distributions in the Culebra Dolomite Member of the Permian Rustler Formation at the WIPP site. The results of this study are intended to support Sandia National Laboratories performance-assessment calculations. The three-dimensional finite-difference code SWIFT II was employed for the numerical modeling, using a variable-fluid-density and single-porosity formulation. The spatial scale of the model, 21.3 km by 30.6 km, was chosen to allow simulation of regional-scale pumping tests conducted at the H-3 and H-11 hydropads and the WIPP-13 borehole, which are located south, southeast, and northwest, respectively, of the center of the WIPP site. The modeled area includes and extends beyond the controlled area defined by the WIPP-site boundaries. The work performed in this study consisted of modeling the hydrogeology of the Culebra in two stages: steady-state modeling to develop the best estimate of the undisturbed head distribution (i.e., of the hydraulic conditions before excavation of the WIPP shafts, which began in 1981) and superimposed transient modeling of local hydrologic response to excavation of the four WIPP shafts at the center of the WIPP site, as well as to various well tests. The transient modeling used the calculated steady-state freshwater heads as initial conditions. 144 refs., 98 figs., 23 tabs.

  20. Flow assurance intervention, hydrates remediation

    Energy Technology Data Exchange (ETDEWEB)

    Mancini, Christopher S. [Oceaneering International Inc., Houston, TX (United States)

    2012-07-01

    This paper addresses the issues of removing hydrates in sub sea flow lines and associated equipment with an Remotely Operated Vehicle (ROV) of opportunity and a multi-service-vessel (MSV). The paper is split into three topics: the equipment used with the ROV, assessing the interface points and handling fluids produced from drawing down the pressure. Each section is explained thoroughly and backed up with real world experience. The equipment section details information from actual jobs performed and why the particular components were utilized. The system is generally contained in an ROV mounted skid. Pumps are utilized to draw down the pressure inside the hydrated section of equipment, removing one of the three necessary components for hydrates formation. Once the section is pumped down, several options exist for handling the fluids pumped out of the system: pumping to surface, re-injection into the well, or injection into an operating flow line. This method of hydrates remediation is both economical and timely. Hydrate blockages form in low temperatures and high pressures. Reducing the pressure or increasing the temperature so the conditions lie to the right of the hydrate dissociation curve will slowly decompose the blockage. Depressurization and the use of MEG or methanol will give favorable conditions to remove the hydrate plug. Oceaneering has the capabilities to remove hydrates using the FRS in conjunction with an installation vessel to dispose of the gas and fluid removed from the flow line. Hydrate remediation techniques should be implemented into the initial design to reduce costs later. The cost of stopped production combined with the day rate for equipment needed for hydrate removal outweighs the costs if no technique is utilized. (author)

  1. Hydrogeochemistry Of A Modern Dolomite-Forming Lagoon System, Cabo Frio-RJ, Brazil

    Science.gov (United States)

    Moreira, N. F.; Walter, L. M.

    2004-12-01

    Two hypersaline, dolomite-forming lagoons near Cabo Frio, Brazil, and associated ground- and surface waters were sampled in a comparative sediment and fluid geochemical (solutes, stable isotopes) investigation. Although microbial mediation via sulfate reducers has been invoked to explain dolomite formation in these lagoons, we showed that dolomites are associated with sulfide oxidation (Moreira et al., 2004). Sulfide oxidation is thought to promote dolomite formation by causing undersaturation for competing carbonate phases such as Mg-calcite. Herein, we consider the larger hydrogeologic and temporal setting to further elucidate hydrogeochemical and geochemical constraints on rates and mechanisms of dolomite formation in the two lagoons. The lagoons, Brejo do Espinho (BE) and Lagoa Vermelha (LV), are shallow marginal marine systems flanked by quartz sand dunes separating them from Atlantic open seawater to the south and from Araruama lagoon, a large, hypersaline water body, to the north. In both lagoons, about 1 m of high Mg-calcite and dolomite mud has accumulated over the last 5,000 years on an underlying aquifer composed of highly permeable, quartz-rich coquinas. BE has a proximal relation to recharge from Araruama lagoon, while LV is more closely associated with meteoric recharge from lacustrine and riverine systems. BE is shallower, at 0.5 m water depth, than LV (2 m), permitting BE waters to remain oxic. Oxygen isotope values and chloride mass balances of pore waters and of fluids sampled from shallow ground water wells identify the different water and solute sources the lagoons. BE overlying brines and pore waters appear to be produced by evapoconcentration of Araruama source brines and meteoric precipitation. In contrast, LV derives from evapoconcentrated seawater mixed with regional lake and ground water sources. We envision a scenario in which dense, Mg-SO4-rich brines from Araruama migrate along a permeable flowpath in limited contact with the atmosphere

  2. 40 CFR 180.1232 - Lime-sulfur; exemption from the requirement of a tolerance.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Lime-sulfur; exemption from the... Exemptions From Tolerances § 180.1232 Lime-sulfur; exemption from the requirement of a tolerance. An exemption from the requirement of a tolerance is established for residues of lime-sulfur....

  3. 40 CFR 180.1231 - Lime; exemption from the requirement of a tolerance.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Lime; exemption from the requirement... From Tolerances § 180.1231 Lime; exemption from the requirement of a tolerance. An exemption from the requirement of a tolerance is established for residues of lime....

  4. Effect of dolomite on the repair of bone defects in rats: histological study.

    Science.gov (United States)

    Moreschi, Eduardo; Hernandes, Luzmarina; Dantas, Jailson Araujo; da Silva, Maria Angélica Raffaini Covas Pereira; Casaroto, Ana Regina; Bersani-Amado, Ciomar Aparecida

    2010-12-01

    The aim of the present study was to evaluate histologically and radiographically the tissue response to dolomite [CaMg(CO3)2] and its osteogenic potential in the repair of bone cavities in the calvaria of rats. A bone defect 10 mm in diameter and 1 mm deep was made in the calvaria of male Wistar rats. The defects were filled with dolomite, inorganic bovine bone (positive control), or coagulum (negative control). The animals were euthanized 7, 15, 30, and 60 days after surgery, and specimens were collected for radiographic and microscopic analyses. The bone defects were processed for paraffin embedding and H&E staining. The histological study revealed that dolomite stimulated a moderate inflammatory response, with programmed cell death in the first 15 days, compared to bovine bone which showed a moderate to intense acute response. In the chronic phase, the inflammatory response was characterized by the occurrence of macrophages organized as epithelioid cells in the dolomite group, and giant cells in the bovine-bone group. Fibrosis developed in all three groups; however, encapsulation of the fragments, reabsorption, and osteoconductive activity occurred only in the defects filled with bovine bone. The radiographic analysis showed that the bovine bone was most efficient in the repair of the defects, followed by the dolomite and the coagulum. This study demonstrated that the dolomite stimulated a moderate acute inflammatory response with programmed cell death, and a chronic inflammatory response by means of the phagocytic mononuclear system. Although osteo-conductive activity was not shown, the dolomite favored the repair process, compared to the coagulum group.

  5. Investigation on Gas Storage in Methane Hydrate

    Institute of Scientific and Technical Information of China (English)

    Zhigao Sun; Rongsheng Ma; Shuanshi Fan; Kaihua Guo; Ruzhu Wang

    2004-01-01

    The effect of additives (anionic surfactant sodium dodecyl sulfate (SDS), nonionic surfactant alkyl polysaccharide glycoside (APG), and liquid hydrocarbon cyclopentane (CP)) on hydrate induction time and formation rate, and storage capacity was studied in this work. Micelle surfactant solutions were found to reduce hydrate induction time, increase methane hydrate formation rate and improve methane storage capacity in hydrates. In the presence of surfactant, hydrate could form quickly in a quiescent system and the energy costs of hydrate formation were reduced. The critical micelle concentrations of SDS and APG water solutions were found to be 300× 10-6 and 500× 10-6 for methane hydrate formation system respectively. The effect of anionic surfactant (SDS) on methane storage in hydrates is more pronounced compared to a nonionic surfactant (APG). CP also reduced hydrate induction time and improved hydrate formation rate, but could not improve methane storage in hydrates.

  6. Dolomite Problem”and Experimental Studies of Dolomite Formation%“白云石问题”及其实验研究

    Institute of Scientific and Technical Information of China (English)

    张亦凡; 马怡飞; 姚奇志; 钱飞进; 王雨晗; 李涵; 周根陶

    2015-01-01

    Dolomite problem is undoubtedly one of the most interesting and confusing problems in geology. As a common carbonate mineral, dolomite is abundant in geological history but rarely occurs in modern ocean sediments. It is nearly impossible to precipitate dolomite below 100℃. Dolomite, [CaMg(CO3)2], has a cation ordering structure and its space group is R-3. Additionally, it is thermodynamically stable under the condition of earth's surface. Although researchers tried to mimic physical and chemical conditions of natural environments which can form dolomite, these experiments still can not successfully precipitate ordered dolomite. Fully ordered dolomite can only form in hydrothermal experiments upper 200℃. It seems that the formation of dolomite is a dynamically controlling process. Recently, microbial dolomite model has been widely accepted. In this model, microbial activity is considered as the key of dolomite formation at low temperature. Many microbial mineralization experiments have confirmed that the existence of microorganisms can indeed promote the formation of high-magnesium calcite. Solving“dolomite problem”can not only help understanding the genesis of dolomite, but also promote the development of mineralogy theory. This review summarized current progresses of dolomite synthetic experiments, including experiments at high and low temperatures and microbially induced experiments. We also clarified the limitations of current understanding to“dolomite problem”. Future perspectives were proposed to better understand and finally solve dolomite problem.%“白云石问题”无疑是地质学上最有趣最长久的难题之一。作为一种常见的碳酸盐矿物,白云石在地质历史时期大量发育,却在现代海洋沉积环境中鲜少沉积,并且在实验室模拟海水条件下也几乎无法低温合成。白云石[CaMg(CO3)2]不同于Ca2+、Mg2+无序的高镁方解石,具有阳离子有序超结构,空间群为R-3,在地

  7. Comparative cytotoxicity of dolomite nanoparticles in human larynx HEp2 and liver HepG2 cells.

    Science.gov (United States)

    Ahamed, Maqusood; Alhadlaq, Hisham A; Ahmad, Javed; Siddiqui, Maqsood A; Khan, Shams T; Musarrat, Javed; Al-Khedhairy, Abdulaziz A

    2015-06-01

    Dolomite is a natural mineral of great industrial and commercial importance. With the advent of nanotechnology, natural minerals including dolomite in the form of nanoparticles (NPs) are being utilized in various applications to improve the quality of products. However, safety or toxicity information of dolomite NPs is largely lacking. This study evaluated the cytotoxicity of dolomite NPs in two widely used in vitro cell culture models: human airway epithelial (HEp2) and human liver (HepG2) cells. Concentration-dependent decreased cell viability and damaged cell membrane integrity revealed the cytotoxicity of dolomite NPs. We further observed that dolomite NPs induce oxidative stress in a concentration-dependent manner, as indicated by depletion of glutathione and induction of reactive oxygen species (ROS) and lipid peroxidation. Quantitative real-time PCR data demonstrated that the mRNA level of tumor suppressor gene p53 and apoptotic genes (bax, CASP3 and CASP9) were up-regulated whereas the anti-apoptotic gene bcl-2 was down-regulated in HEp2 and HepG2 cells exposed to dolomite NPs. Moreover, the activity of apoptotic enzymes (caspase-3 and caspase-9) was also higher in both kinds of cells treated with dolomite NPs. It is also worth mentioning that HEp2 cells seem to be marginally more susceptible to dolomite NPs exposure than HepG2 cells. Cytotoxicity induced by dolomite NPs was efficiently prevented by N-acetyl cysteine treatment, which suggests that oxidative stress is primarily responsible for the cytotoxicity of dolomite NPs in both HEp2 and HepG2 cells. Toxicity mechanisms of dolomite NPs warrant further investigations at the in vivo level.

  8. Lime pretreatment and fermentation of enzymatically hydrolyzed sugarcane bagasse.

    Science.gov (United States)

    Rabelo, Sarita C; Maciel Filho, Rubens; Costa, Aline C

    2013-03-01

    Sugarcane bagasse was subjected to lime (calcium hydroxide) pretreatment and enzymatic hydrolysis for second-generation ethanol production. A central composite factorial design was performed to determine the best combination of pretreatment time, temperature, and lime loading, as well as to evaluate the influence of enzymatic loadings on hydrolysis conversion. The influence of increasing solids loading in the pretreatment and enzymatic hydrolysis stages was also determined. The hydrolysate was fermented using Saccharomyces cerevisiae in batch and continuous mode. In the continuous fermentation, the hydrolysates were concentrated with molasses. Lime pretreatment significantly increased the enzymatic digestibility of sugarcane bagasse without the need for prior particle size reduction. In the optimal pretreatment conditions (90 h, 90 °C, 0.47 glime/g bagasse) and industrially realistic conditions of hydrolysis (12.7 FPU/g of cellulase and 7.3 CBU/g of β-glucosidase), 139.6 kglignin/ton raw bagasse and 126.0 kg hemicellulose in the pretreatment liquor per ton raw bagasse were obtained. The hydrolysate from lime pretreated sugarcane bagasse presented low amounts of inhibitors, leading to ethanol yield of 164.1 kgethanol/ton raw bagasse.

  9. K'qizaghetnu Ht'ana (Stories from Lime Village).

    Science.gov (United States)

    Bobby, Pete; And Others

    A cross section of Athabascan life as related by eight inhabitants of Lime Village, Alaska, is given in this document. The short narratives are printed in English and in Dena'ina. Illustrations accompany the text. The stories tell of making eagle feather robes, birchbark or mooseskin boats, a raincoat from black bear intestines, and boots from…

  10. Performance of sand-lime products made with plastic waste

    Directory of Open Access Journals (Sweden)

    Nowek Milena

    2016-01-01

    Full Text Available The paper describes the studies on the sand-lime (silicate masonry units modified with recycled plastics in various forms: regranulate, regrind and powder. The following materials were examined: high impact polystyrene (HIPS and acrylonitrile butadiene styrene (ABS. The results of the functional properties tests, such as compressive strength, softening behavior, bulk density and water absorption are presented in the article. The microstructure of the products was analyzed using SEM and XRD methods.Obtained results show that the properties of modified product largely depend on the type, form and amount of used polymer. The highest compressive strength was achieved with 15% of HIPS regranulate in the product (by weight. ABS does not improve the strength of the sample, however, it does block the capillary action in the sand-lime product. The lowest softening coefficient was obtained in the sample modified with HIPS regranulate. The examined polymers contributed to decrease in bulk density of the samples as well as lowered their water absorption. The samples with pulverized polymer have the worst properties. All the results are compared with those of the traditional sand-lime bricks and sand-lime product modified with other additives. The analysis indicate that silicate masonry units with post-production and post-consumption plastic waste can possess interesting functional properties what brings a new potential possibility to dispose of still growing number of plastic waste.

  11. EFFECTS OF LIME (CAO) ON THE ENDOTOXIN LEVELS OF BIOSOLIDS

    Science.gov (United States)

    Lime addition is a common practice for treating biosolids in order to meet EPA 503 requirements for land application. Since this treatment kills the majority of microorganisms, will it increase the level of endotoxins present in biosolids? And, if endotoxin levels are increased, ...

  12. STRUCTURAL AND GEOCHEMICAL CHARACTERISTICS OF SECONDARY DOLOMITIC BODIES OF CRETACEOUS COLIMA-JALISCO BASIN, WESTERN MEXICO

    Science.gov (United States)

    Zarate, P. F.

    2009-12-01

    The cretaceous Colima-Jalisco basin, at western Mexico, is characterized by the development of volcano sedimentary sequences belonging to the Late Jurassic-Early Cretaceous Alisitos-Teloloapan arc-island and the formation of volcanogenic massive sulphide deposits ("El Cuale", "La Minita", "Talpa de Allende"). Some bodies of dolomite have been described and have been classified into two groups in accordance with its secondary origin: sabkha (diagenetic) and hydrothermal. In both cases the primary dolomitized limestone belongs to the reef facies of the Tepalcatepec Formation (TF) of Albian-Cenomanian characterized by the next geochemical content: MgO (0.42%), CaO (53.7%), SiO2 (0.15%), Pb (140 ppm) and Zn (50 ppm). Diagenetical dolomite is characterized by an stratiform body and its contacts are consistent with the structural attitude of TF to which it belongs. In the dolomites formed by hydrothermal replacement process is limited by faults and fractures, thus its morphology is irregular and their contacts are discordant, adopting domic or columnar forms. Occasionally hydrothermal dolomite can be associated with concentrations of lead, zinc, silver and barite. The dolomitic body called "Cerro El Puro", (19° 3.7' N; 103° 36.7' W), located at 20 km SE 30° from Colima City, consists in a carbonate horizon of 300 m thick and over 5 km in length and is consistent with the structural attitude (N30°W; NE50°) of the southwestern flank of the syncline Tepames-Amarradero, in which southeast extreme an evaporitic stratiform deposits. The dolomite of this body is of ankeritic type, hence its typical light reddish brown. The geochemical content is shown on Table 1. After the structural and geochemical features of this dolomite, it is classified as sabkha with a diagenetic origin. The other dolomitic outcrop studied is called “Cerro Bola” (18°54'N; 103°47.5'W) which is located 40 km S10°W from Colima City, and consists of a single dolomitic outcrop, black in color

  13. Secondary Magnetization of ZEBRA Dolomites in the Basin and Range Province of Eastern Nevada

    Science.gov (United States)

    Elmore, R. D.; Dulin, S. A.

    2013-12-01

    Zebra dolomites within the Devonian Guilmette Formation of the southern Basin and Range Province, Nevada, are the focus of a paleomagnetic study to determine if a characteristic magnetization exists that will yield insight into the timing of zebra dolomite formation. Zebra dolomites consist of alternating bands of light and dark dolomite, and are found throughout Nevada, often associated with mineralized ore deposits. Although a variety of mechanisms have been suggested for formation, the zebra dolomite throughout Nevada is likely associated with hydrothermal fluid migration. The current study focuses on zebra dolomites that have formed in close stratigraphic proximity and within the Alamo Breccia in the Delamar Range in southeastern Nevada. The Alamo Breccia is an impact generated mega-breccia zone within the Devonian Guilmette Formation. The zebra dolomites, including those in the Alamo Breccia, and host Guilmette in the Delamar Range have a characteristic remanent magnetization (ChRM) with maximum laboratory unblocking temperatures of 480°C that is interpreted to reside in magnetite. The rocks were structurally rotated to remove Cenozoic extension, and the stratigraphic mean direction of the ChRM has a declination of 164.4°, with an inclination of -3°. The calculated pole is at 51.6°N, 90.7°E (dp = 2.2, dm = 4.3) which lies near the late Triassic portion of the apparent polar wander path (APWP) for North America. Based on low burial temperatures, this ChRM is interpreted as a chemical remanent magnetization (CRM) that was acquired due to the mobilization of brines possibly associated with the Triassic Sonoma orogeny. Geochemical data are consistent with alteration by externally derived fluids. The presence of a late Triassic magnetization indicates that the zebra dolomite can be no younger than Late Triassic. Preliminary results from zebra dolomites in other areas in southeastern Nevada indicate a more complex magnetization; some locations contain both

  14. Suboxic dolomite formation linked to the sedimentary Mn cycle, Archipelago Los Roques, Venezuela

    Science.gov (United States)

    Petrash, D.; Lalonde, S.; Gonzalez, G.; Gingras, M.; Konhauser, K.

    2013-12-01

    The preferential formation of Ca-rich dolomite precursors in modern peritidal environments has been associated with the degradation of buried microbial mats, with complexation of Ca and Mg cations by extracellular polysaccharides, and alkalinity generation, mostly through bacterial sulfate reduction. However, it remains unclear why Ca-dolomite would not occur in suboxic sediments where bacterial Mn(IV) and/or Fe(III) reduction are important sources of alkalinity, and the role, if any, of Fe- and Mn-recycling in its diagenetic stabilization to more stoichiometric dolomite is unknown. In a shoaling-upward parasequence in the Archipelago Los Roques, Venezuela, an abundance of Ca-dolomite coincides with a relative decrease in bulk-sediment iron concentrations. These sediments were analyzed with multiple analytical tools, including EPMA, ICP-MS, synchrotron-based XRF, XRD, and spatially resolved XANES. Results demonstrate that the distribution of spheroidal aggregates of nanometer-scale Ca-rich dolomite rhombohedra is linked with interstitial elemental sulfur and manganese accumulations, with Mn occurring in several oxidation states (Fig. 1). Based on our observations at this novel dolomite-forming site, we suggest that in peritidal settings the burial of metal-reactive microbial mats act as a barrier capable of concentrating dissolved reactive species that promote greater sediment residence times in suboxic (manganic) zones, where the recycling of Mn not only plays an important role in the remineralization of organic matter, but also sustains elevated alkalinity and dissolved pore water sulfide concentrations. The last two effects have been previously suggested to promote Mg dehydration, the major kinetic barrier to dolomite nucleation. Figure 1. Normalized Mn K-edge merged spectra of a 5 x 5 μm analytical area bearing dolomite cements. A: The K-edge exhibits two main features at about 6554 and 6558 eV. B: Intermediate Mn (III) is identified by the positive slope of

  15. A Model for Dissolution of Lime in Steelmaking Slags

    Science.gov (United States)

    Sarkar, Rahul; Roy, Ushasi; Ghosh, Dinabandhu

    2016-08-01

    In a previous study by Sarkar et al. (Metall. Mater. Trans. B 46B:961 2015), a dynamic model of the LD steelmaking was developed. The prediction of the previous model (Sarkar et al. in Metall. Mater. Trans. B 46B:961 2015) for the bath (metal) composition matched well with the plant data (Cicutti et al. in Proceedings of 6th International Conference on Molten Slags, Fluxes and Salts, Stockholm City, 2000). However, with respect to the slag composition, the prediction was not satisfactory. The current study aims to improve upon the previous model Sarkar et al. (Metall. Mater. Trans. B 46B:961 2015) by incorporating a lime dissolution submodel into the earlier one. From the industrial point of view, the understanding of the lime dissolution kinetics is important to meet the ever-increasing demand of producing low-P steel at a low basicity. In the current study, three-step kinetics for the lime dissolution is hypothesized on the assumption that a solid layer of 2CaO·SiO2 should form around the unreacted core of the lime. From the available experimental data, it seems improbable that the observed kinetics should be controlled singly by any one kinetic step. Accordingly, a general, mixed control model has been proposed to calculate the dissolution rate of the lime under varying slag compositions and temperatures. First, the rate equation for each of the three rate-controlling steps has been derived, for three different lime geometries. Next, the rate equation for the mixed control kinetics has been derived and solved to find the dissolution rate. The model predictions have been validated by means of the experimental data available in the literature. In addition, the effects of the process conditions on the dissolution rate have been studied, and compared with the experimental results wherever possible. Incorporation of this submodel into the earlier global model (Sarkar et al. in Metall. Mater. Trans. B 46B:961 2015) enables the prediction of the lime dissolution rate

  16. Kinetic modeling of liquid-phase adsorption of phosphate on dolomite.

    Science.gov (United States)

    Karaca, S; Gürses, A; Ejder, M; Açikyildiz, M

    2004-09-15

    The adsorption of phosphate from aqueous solution on dolomite was investigated at 20 and 40 degrees C in terms of pseudo-second-order mechanism for chemical adsorption as well as an intraparticle diffusion mechanism process. Adsorption was changed with increased contact time, initial phosphate concentration, temperature, solution pH. A pseudo-second-order model and intraparticle diffusion model have been developed to predict the rate constants of adsorption and equilibrium capacities. The activation energy of adsorption can be evaluated using the pseudo-second-order rate constants. The adsorption of phosphate onto dolomite are an exothermically activated process. A relatively low activation energy and a model highly fitting to intraparticle diffusion suggest that the adsorption of phosphate by dolomite may involve not only physical but also chemisorption. This was likely due to its combined control of chemisorption and intraparticle diffusion. However, for phosphate/dolomite system chemical reaction is important and significant in the rate-controlling step, and for the adsorption of phosphate onto dolomite the pseudo-second-order chemical reaction kinetics provides the best correlation of the experimental data.

  17. Structures of dolomite at ultrahigh pressure and their influence on the deep carbon cycle.

    Science.gov (United States)

    Merlini, Marco; Crichton, Wilson A; Hanfland, Michael; Gemmi, Mauro; Müller, Harald; Kupenko, Ilya; Dubrovinsky, Leonid

    2012-08-21

    Carbon-bearing solids, fluids, and melts in the Earth's deep interior may play an important role in the long-term carbon cycle. Here we apply synchrotron X-ray single crystal micro-diffraction techniques to identify and characterize the high-pressure polymorphs of dolomite. Dolomite-II, observed above 17 GPa, is triclinic, and its structure is topologically related to CaCO(3)-II. It transforms above 35 GPa to dolomite-III, also triclinic, which features carbon in [3 + 1] coordination at the highest pressures investigated (60 GPa). The structure is therefore representative of an intermediate between the low-pressure carbonates and the predicted ultra-high pressure carbonates, with carbon in tetrahedral coordination. Dolomite-III does not decompose up to the melting point (2,600 K at 43 GPa) and its thermodynamic stability demonstrates that this complex phase can transport carbon to depths of at least up to 1,700 km. Dolomite-III, therefore, is a likely occurring phase in areas containing recycled crustal slabs, which are more oxidized and Ca-enriched than the primitive lower mantle. Indeed, these phases may play an important role as carbon carriers in the whole mantle carbon cycling. As such, they are expected to participate in the fundamental petrological processes which, through carbon-bearing fluids and carbonate melts, will return carbon back to the Earth's surface.

  18. Dolomite-rich coralline algae in reefs resist dissolution in acidified conditions

    Science.gov (United States)

    Nash, M. C.; Opdyke, B. N.; Troitzsch, U.; Russell, B. D.; Adey, W. H.; Kato, A.; Diaz-Pulido, G.; Brent, C.; Gardner, M.; Prichard, J.; Kline, D. I.

    2013-03-01

    Coral reef ecosystems develop best in high-flow environments but their fragile frameworks are also vulnerable to high wave energy. Wave-resistant algal rims, predominantly made up of the crustose coralline algae (CCA) Porolithon onkodes and P. pachydermum, are therefore critical structural elements for the survival of many shallow coral reefs. Concerns are growing about the susceptibility of CCA to ocean acidification because CCA Mg-calcite skeletons are more susceptible to dissolution under low pH conditions than coral aragonite skeletons. However, the recent discovery of dolomite (Mg0.5Ca0.5(CO3)), a stable carbonate, in P. onkodes cells necessitates a reappraisal of the impacts of ocean acidification on these CCA. Here we show, using a dissolution experiment, that dried dolomite-rich CCA have 6-10 times lower rates of dissolution than predominantly Mg-calcite CCA in both high-CO2 (~ 700ppm) and control (~ 380ppm) environments, respectively. We reveal this stabilizing mechanism to be a combination of reduced porosity due to dolomite infilling and selective dissolution of other carbonate minerals. Physical break-up proceeds by dissolution of Mg-calcite walls until the dolomitized cell eventually drops out intact. Dolomite-rich CCA frameworks are common in shallow coral reefs globally and our results suggest that it is likely that they will continue to provide protection and stability for coral reef frameworks as CO2 rises.

  19. Structures of dolomite at ultrahigh pressure and their influence on the deep carbon cycle

    Science.gov (United States)

    Merlini, Marco; Crichton, Wilson A.; Hanfland, Michael; Gemmi, Mauro; Müller, Harald; Kupenko, Ilya; Dubrovinsky, Leonid

    2012-01-01

    Carbon-bearing solids, fluids, and melts in the Earth's deep interior may play an important role in the long-term carbon cycle. Here we apply synchrotron X-ray single crystal micro-diffraction techniques to identify and characterize the high-pressure polymorphs of dolomite. Dolomite-II, observed above 17 GPa, is triclinic, and its structure is topologically related to CaCO3-II. It transforms above 35 GPa to dolomite-III, also triclinic, which features carbon in [3 + 1] coordination at the highest pressures investigated (60 GPa). The structure is therefore representative of an intermediate between the low-pressure carbonates and the predicted ultra-high pressure carbonates, with carbon in tetrahedral coordination. Dolomite-III does not decompose up to the melting point (2,600 K at 43 GPa) and its thermodynamic stability demonstrates that this complex phase can transport carbon to depths of at least up to 1,700 km. Dolomite-III, therefore, is a likely occurring phase in areas containing recycled crustal slabs, which are more oxidized and Ca-enriched than the primitive lower mantle. Indeed, these phases may play an important role as carbon carriers in the whole mantle carbon cycling. As such, they are expected to participate in the fundamental petrological processes which, through carbon-bearing fluids and carbonate melts, will return carbon back to the Earth’s surface. PMID:22869705

  20. Hydrates fighting tools; Des outils de lutte contre les hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2003-04-01

    Shell Exploration and Production company (SEPCo) is the operator of the 'Popeye' deep offshore field in the Gulf of Mexico. Thanks to the introduction of a low dosing hydrates inhibitor (LDHI) elaborated by Shell Global Solutions, the company has added a 7.5 Gpc extra volume of gas to its recoverable reserves. This new technology avoids the plugging of pipes by hydrates formation. (J.S.)

  1. Effect of liquid liming on sorghum growth in an Ultisol.

    Directory of Open Access Journals (Sweden)

    Manuel E. Camacho

    2015-06-01

    Full Text Available   The aim of this study was to evaluate the effects of the application of liquid lime on sorghum growth in an Ultisol. This research was conducted between August and November, 2011 at the Agricultural Research Center, San José, Costa Rica. In an Ultisol planted with sorghum, in pots of 800 ml, the following treatments where applied: control without lime, calcium carbonate at doses of 10 and 20 l/ha, magnesium oxide at doses of 10 and 20 l/ha, calcium carbonate + magnesium oxide at doses of 5 + 5 and 10 + 10 l/ha, respectively. Six weeks after planting, sorghum was harvested, measuring leaf area, dry and fresh weight of the aerial and root biomass, nutrient absorption and the soil chemical characteristics. Treatments using calcium carbonate and calcium carbonate + magnesium oxide obtained the best values of leaf area and the higher weight of the aerial and root biomass of sorghum. Even though there were no significant differences between liquid lime treatments, there were regarding control without lime and weight biomass variables. Liquid calcium carbonate significantly increased Ca absorption, and the calcium carbonate + magnesium oxide treatment at doses of 10 l/h showed the highest Mg absorption. All amendment treatments caused an improvement of the soil fertility, the most notable being the application of 20 l/ha of magnesium oxide that dropped the exchangeable acidity from 9.02 to 0.36 cmol(+/l, acidity saturation dropped from 95 to 3.3%, and pH increased from 5 to 5.7. It was concluded that the liquid liming amendments had a positive effect over the crop and the soil fertility.

  2. The relationships among lemons, limes and citron: a chromosomal comparison.

    Science.gov (United States)

    Carvalho, R; Soares Filho, W S; Brasileiro-Vidal, A C; Guerra, M

    2005-01-01

    Lemons, limes and citron constitute a group of closely related Citrus species, whose species delimitations and taxonomic relationships are unclear. In order to identify karyotypic similarities and species relationships within this group, the CMA+/DAPI- banding pattern and the distribution of the 5S and 45S rDNA sites of 10 accessions of lime, lemon, and citron were investigated. The four cultivars of C. limon analyzed showed the same pattern of CMA+ bands and rDNA sites, suggesting that they originated from a single germplasm, later differentiated by distinct somatic mutations. The lemons C. jambhiri, C. limonia and C. volkameriana displayed karyotypes very similar to each other, but they differed from C. limon by the absence of a single chromosome with one band in each telomere. The limes, C. aurantifolia and C. limettioides, seemed less related to each other and exhibited different heteromorphic chromosome pairs. In C. aurantifolia, the presence of a chromosome type unknown in all other Citrus species cytologically known so far supports the assumption that this accession may be derived from a hybrid with a species from the subgenus Papeda or from another genus. Citrus medica was the only homozygous accession of this group and all of its chromosome types were clearly represented in limes and lemons, some of them forming heteromorphic pairs. The analysis of the distribution of rDNA sites allowed a further refinement of the comparison among accessions. The lemons and limes were heterozygous for all rDNA sites, whereas C. medica was entirely homozygous. These data support the hypothesis that C. medica is a true species while the other nine accessions are hybrids. Copyright 2005 S. Karger AG, Basel.

  3. The properties of doped sand-lime products

    Directory of Open Access Journals (Sweden)

    Dachowski Ryszard

    2016-01-01

    Full Text Available Sand-lime products are natural materials consisting of lime, sand and water with the least content of radioactive elements in comparison to other masonry elements. They are characterized by very high compressive strength, high acoustic insulation, good thermal properties, provide a friendly atmosphere and prevent the spread of mold and bacterial flora. In addition they are fully recyclable. White bricks through the porous structure and the occurrence of capillaries have the ability to rising water. The height of capillary action is dependent on the contact angle and the size of existing pores in the material. This property affects the frost resistance and other characteristics of durability of wall materials operated under conditions of intense exposure to moisture. The aim of the study is to determine the impact modifier on the properties of autoclaved sand-lime products. For testing used autoclaved sand-lime brick dimensions 40x40x160 [mm]. The weight of the products consists of 5% lime, 90% sand and 5% lithium water glass (MP=2,6 and MP=7,0. The produced samples were subjected to autoclaving at temperatures of 203◦C and pressure of 1.6 MPa in collaboration with the Silicate Production Plant in Ludynia. Three finished sets of samples (standard, modified with lithium silicate 2.6 and 7.0 have been immersed in water to the desired height during certain time. The results show the diversity of the internal structure of the tested products. In particular pore distribution, size and volume.

  4. Adhesive carrier particles for rapidly hydrated sorbent for moderate-temperature dry flue gas desulfurization.

    Science.gov (United States)

    Li, Yuan; You, Changfu; Song, Chenxing

    2010-06-15

    A rapidly hydrated sorbent for moderate-temperature dry flue gas desulfurization was prepared by rapidly hydrating adhesive carrier particles and lime. The circulation ash from a circulating fluidized bed boiler and chain boiler ash, both of which have rough surfaces with large specific surface areas and specific pore volumes, can improve the adhesion, abrasion resistance, and desulfurization characteristics of rapidly hydrated sorbent when used as the adhesive carrier particles. The adhesion ability of sorbent made from circulation ash is 67.4% higher than that of the existing rapidly hydrated sorbent made from fly ash, the abrasion ratio is 76.2% lower, and desulfurization ability is 14.1% higher. For sorbent made from chain boiler ash, the adhesion ability is increased by 74.7%, the desulfurization ability is increased by 30.3%, and abrasion ratio is decreased by 52.4%. The abrasion ratios of the sorbent made from circulation ash having various average diameters were all about 9%, and their desulfurization abilities were similar (approximately 150 mg/g).

  5. HYDRATION CHARACTERISTICS OF PROMPT CEMENT IN THE PRESENCE CITRIC ACID AS RETARDER

    Directory of Open Access Journals (Sweden)

    Mohamed Heikal

    2015-03-01

    Full Text Available The aim of the present work is to study the influence of citric acid (CA as retarder on the properties of prompt cement pastes. The dosages of CA were 0.50, and 0.75, 1.00 and 1.25 mass % of prompt cement. The initial and final setting times, bulk density, compressive strength, total porosity, and hydration kinetics such as free lime, combined water contents and XRD for selected sample were investigated. The results obtained in this study showed that the addition of CA elongates the initial and final setting times and decreases the compressive strength and combined water contents, whereas, it increases the total porosity at all ages of hydration. CA retards the liberation of Ca(OH2 of prompt pastes. The free lime contents of prompt cement pastes are slightly increased up to 28 days then sharply increased up to 90 days. Thus, it is suggested that citrate sorbed onto the clinker surface and formed a protective layer around the clinker grains retarding their dissolution. The sharp increase of compressive strength at later ages after 28 days up to 90 days. The presence of 0.75 mass % citric acid achieves the initial and final setting time of the prompt cement according to the ASTM specification.

  6. [Study on Archaeological Lime Powders from Taosi and Yinxu Sites by FTIR].

    Science.gov (United States)

    Wei, Guo-feng; Zhang, Chen; Chen, Guo-liang; He, Yu-ling; Gao, Jiang-tao; Zhang, Bing-jian

    2015-03-01

    Archaeological lime powders samples from Taosi and Yinxu sites, natural limestone and experimentally prepared lime mortar were investigated by means of Fourier transform infrared spectrometry (FTIR) to identify the raw material of lime powders from Taosi and Yinxu sites. Results show that ν2/ν4 ratio of calcite resulted from carbonation reaction of man-made lime is around 6.31, which is higher than that of calcite in natural limestone and reflects the difference in the disorder of calcite crystal structure among the natural limestone and prepared lime mortar. With additional grinding, the values of v2 and ν4 in natural limestone and prepared lime mortar decrease. Meanwhile, the trend lines of ν2 versus ν4 for calcite in experimentally prepared lime mortar have a steeper slope when compared to calcite in natural limestone. These imply that ν2/ν4 ratio and the slope of the trend lines of ν2 versus ν4 can be used to determine the archaeological man-made lime. Based on the experiment results, it is possible that the archaeological lime powder from Taosi and Yinxu sites was prepared using man-made lime and the ancient Chinese have mastered the calcining technology of man-made lime in the late Neolithic period about 4 300 years ago.

  7. Obsidian Hydration: A New Paleothermometer

    Energy Technology Data Exchange (ETDEWEB)

    Anovitz, Lawrence {Larry} M [ORNL; Riciputi, Lee R [ORNL; Cole, David R [ORNL; Fayek, Mostafa [ORNL; Elam, J. Michael [University of Tennessee, Knoxville (UTK)

    2006-01-01

    The natural hydration of obsidian was first proposed as a dating technique for young geological and archaeological specimens by Friedman and Smith (1960), who noted that the thickness of the hydrated layer on obsidian artifacts increases with time. This approach is, however, sensitive to temperature and humidity under earth-surface conditions. This has made obsidian hydration dating more difficult, but potentially provides a unique tool for paleoclimatic reconstructions. In this paper we present the first successful application of this approach, based on combining laboratory-based experimental calibrations with archaeological samples from the Chalco site in the Basin of Mexico, dated using stratigraphically correlated 14C results and measuring hydration depths by secondary ion mass spectrometry. The resultant data suggest, first, that this approach is viable, even given the existing uncertainties, and that a cooling trend occurred in the Basin of Mexico over the past 1450 yr, a result corroborated by other paleoclimatic data.

  8. Obsidian hydration: A new paleothermometer

    Science.gov (United States)

    Anovitz, Lawrence M.; Riciputi, Lee R.; Cole, David R.; Fayek, Mostafa; Elam, J. Michael

    2006-07-01

    The natural hydration of obsidian was first proposed as a dating technique for young geological and archaeological specimens by Friedman and Smith (1960), who noted that the thickness of the hydrated layer on obsidian artifacts increases with time. This approach is, however, sensitive to temperature and humidity under earth-surface conditions. This has made obsidian hydration dating more difficult, but potentially provides a unique tool for paleoclimatic reconstructions. In this paper we present the first successful application of this approach, based on combining laboratory-based experimental calibrations with archaeological samples from the Chalco site in the Basin of Mexico, dated using stratigraphically correlated 14C results and measuring hydration depths by secondary ion mass spectrometry. The resultant data suggest, first, that this approach is viable, even given the existing uncertainties, and that a cooling trend occurred in the Basin of Mexico over the past 1450 yr, a result corroborated by other paleoclimatic data.

  9. Obsidian hydration dates glacial loading?

    Science.gov (United States)

    Friedman, I; Pierce, K L; Obradovich, J D; Long, W D

    1973-05-18

    Three different groups of hydration rinds have been measured on thin sections of obsidian from Obsidian Cliff, Yellowstone National Park, Wyoming. The average thickness of the thickest (oldest) group of hydration rinds is 16.3 micrometers and can be related to the original emplacement of the flow 176,000 years ago (potassium-argon age). In addition to these original surfaces, most thin sections show cracks and surfaces which have average hydration rind thicknesses of 14.5 and 7.9 micrometers. These later two hydration rinds compare closely in thickness with those on obsidian pebbles in the Bull Lake and Pinedale terminal moraines in the West Yellowstone Basin, which are 14 to 15 and 7 to 8 micrometers thick, respectively. The later cracks are thought to have been formed by glacial loading during the Bull Lake and Pinedale glaciations, when an estimated 800 meters of ice covered the Obsidian Cliff flow.

  10. A role for calcium hydroxide and dolomite in water: acceleration of the reaction under ultraviolet light.

    Science.gov (United States)

    Nagase, Hiroyasu; Tsujino, Hidekazu; Kurihara, Daisuke; Saito, Hiroshi; Kawase, Masaya

    2014-04-01

    Organic environmental pollutants are now being detected with remarkably high frequency in the aquatic environment. Photodegradation by ultraviolet light is sometimes used as a method for removing organic chemicals from water; however, this method is relatively inefficient because of the low degradation rates involved, and more efficient methods are under development. Here we show that the removal of various organic pollutants can be assisted by calcined dolomite in aqueous solution under irradiation with ultraviolet light. It was possible to achieve substantial removal of bisphenol A, chlorophenols, alkylphenols, 1-naphthol and 17β-estradiol. The major component of dolomite responsible for the removal was calcium hydroxide. Our results demonstrate that the use of calcium hydroxide with ultraviolet light irradiation can be a very effective method of rapidly removing organic environmental pollutants from water. This is a new role for calcium hydroxide and dolomite in water treatment.

  11. Optimization Study in Biodiesel Production via Response Surface Methodology Using Dolomite as a Heterogeneous Catalyst

    Directory of Open Access Journals (Sweden)

    Regina C. R. Santos

    2014-01-01

    Full Text Available A carbonate mineral, dolomite, was used as a heterogeneous catalyst to produce methyl-esters from soybean oil. The samples were analyzed by XRF, TGA, XRD, TPD-CO2, and SEM. The calcination of dolomite at 800°C/1 h resulted in a highly active mixed metal oxides. In addition, the influence of the reaction variables such as the temperature, catalyst amount, and methanol/soybean oil molar ratio in methyl-ester production was optimized by the application of a central composite design in conjunction with the response surface methodology (RSM. The XRF analysis is carried out after the reuses procedure which shows that the deactivation process is mainly due to the selective calcium leaching. Overall, the calcined dolomite exhibited high catalytic activity at moderate operating conditions for biodiesel production.

  12. Effect of dolomite on reduction swelling property of iron ore pellets

    Institute of Scientific and Technical Information of China (English)

    许斌; 侯通; 陈许玲; 李骞; 姜涛; 李鹏

    2013-01-01

    The effect of various dosages of dolomites on the reduction swelling property of iron ore pellets was studied. Experimental results show that the reduction swelling index(RSI) decreases from 13.35% to 4.0%, while the porosity of roasted pellets increases from 35% to 40% with increasing the dolomite dosage from 0 to 10.5%. Meanwhile, the content of magnesium ferrite with high melting temperature, as well as the stability of magnetite(Fe3 O4) in the roasted pellets, increases with increasing the magnesium oxide(MgO) content from dolomite. The reasons for the decrease of RSI rely on the absence of crystal transformation from Fe2 O3 to Fe3 O4, the increased porosity of roasted pellet, and the suppression of phase transition of 2CaO·SiO2 resulted from the incorporation of magnesium into calcium silicate.

  13. Onset of Crack Initiation in Uniaxial and Triaxial Compression Tests of Dolomite Samples

    Directory of Open Access Journals (Sweden)

    Cieślik Jerzy

    2014-03-01

    Full Text Available The paper presents results of laboratory investigation and analysis of crack initiation threshold identification of dolomite samples. First, selected methods for determining crack initiation thresholds are briefly described with special attention paid to four methods: crack volume strain method [14], change in Poisson’s ratio [8], lateral strain response method [16], and dilatancy method [4]. The investigation performed on dolomite samples shows that for the uniaxial and conventional triaxial compression tests, the above mentioned methods give quite similar values, except for the crack volume strain method. Crack initiation threshold determined by this method has a distinctively lower value than that obtained by the other methods. The aim of the present paper was to review and assess these methods for identifying crack initiation threshold based on laboratory tests of dolomite samples.

  14. Storing natural gas as frozen hydrate

    Energy Technology Data Exchange (ETDEWEB)

    Gudmundsson, J.S.; Khokhar, A.A. (Univ. of Trondheim (Norway)); Parlaktuna, M. (Middle East Technical Univ., Ankara (Turkey))

    1994-02-01

    The formation of natural gas hydrates is a well-known problem in the petroleum and natural gas industries. Hydrates are solid materials that form when liquid water and natural gas are brought in contact under pressure. Hydrate formation need not be a problem. On the contrary, it can be an advantage. The volume of hydrates is much less than that of natural gas. At standard conditions, hydrates occupy 150 to 170 times less volume than the corresponding gas. Typically, natural gas hydrates contain 15% gas and 85% water by mass. It follows that hydrates can be used for large-scale storage of natural gas. Benesh proposed using hydrates to improve the load factor of natural gas supply systems. The author suggested that hydrates could be produced by bringing liquid water into contact with natural gas at the appropriate temperature and high pressure. The hydrate then would be stored at a temperature and pressure where it was stable. When gas was needed for the supply system, the hydrate would be melted at low pressure. The stability of a natural gas hydrate during storage at atmospheric pressure and below-freezing temperatures was studied in the laboratory. The gas hydrate was produced in a stirred vessel at 2- to 6-MPa pressure and temperatures from 0 to 20 C. The hydrate was refrigerated and stored in deep freezers at [minus]5, [minus]10, and [minus]18 C for up to 10 days. The natural gas hydrate remained stable when kept frozen at atmospheric pressure.

  15. {sup 226} Ra committed effective dose assessment for osteoporosis treatment with `Gran-White` dolomite

    Energy Technology Data Exchange (ETDEWEB)

    Pecequilo, Brigitte R.S.; Campos, Marcia P. de [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

    1997-12-01

    A total of 6 dolomite samples were prepared for activity concentration measurement by using high resolution gamma-ray spectrometry. The calculated average specific activity of {sup 226} Ra was 4.34 Bq/kg. The committed effective dose due to the Ra-226 specific activity in dolomite was performed following the ICRP 30 and ICRP 61 procedures and dose conversion factors. Values of 1.95 x 10{sup -6} Sv were obtained for committed effective dose and 5.93 x 10{sup -5} Sv for committed dose equivalent in the bone surface. (author). 9 refs., 2 tabs.

  16. Ferroan dolomite cement in Cambrian sandstones: burial history and hydrocarbon generation of the Baltic sedimentary basin

    DEFF Research Database (Denmark)

    Sliaupa, S.; Cyziene, J.; Molenaar, Nicolaas

    2008-01-01

    . The burial history modelling points to development of most of the dolomite cement during rapid Silurian-Devonian subsidence and Carboniferous-early Permian uplift. A wide range of precipitation temperatures indicate that temperature was not a major factor in triggering the carbonate cementation. Dolomite...... precipitation is related to early stages of organic matter maturation and thus to the oil generation history in the basin. delta C-13 values vary from +0.03% to -6.2%( PDB), suggesting limited addition of carbon from an organic source, with the major part derived from marine bicarbonate. The sourcing of carbon...

  17. Airway Hydration and COPD

    Science.gov (United States)

    Ghosh, Arunava; Boucher, R.C.; Tarran, Robert

    2015-01-01

    Chronic obstructive pulmonary disease (COPD) is one of the prevalent causes of worldwide mortality and encompasses two major clinical phenotypes, i.e., chronic bronchitis (CB) and emphysema. The most common cause of COPD is chronic tobacco inhalation. Research focused on the chronic bronchitic phenotype of COPD has identified several pathological processes that drive disease initiation and progression. For example, the lung’s mucociliary clearance (MCC) system performs the critical task of clearing inhaled pathogens and toxic materials from the lung. MCC efficiency is dependent on: (i) the ability of apical plasma membrane ion channels such as the cystic fibrosis transmembrane conductance regulator (CFTR) and the epithelial Na+ channel (ENaC) to maintain airway hydration; (ii) ciliary beating; and, (iii) appropriate rates of mucin secretion. Each of these components is impaired in CB and likely contributes to the mucus stasis/accumulation seen in CB patients. This review highlights the cellular components responsible for maintaining MCC and how this process is disrupted following tobacco exposure and with CB. We shall also discuss existing therapeutic strategies for the treatment of chronic bronchitis and how components of the MCC can be used as biomarkers for the evaluation of tobacco or tobacco-like-product exposure. PMID:26068443

  18. Mechanism of gypsum hydration

    Directory of Open Access Journals (Sweden)

    Pacheco, G.

    1991-06-01

    Full Text Available There is an hypothesis that the mechanism o f gypsum hydration and dehydration is performed through two simultaneous phenomena. In this study we try to clear up this phenomenon using chlorides as accelerators or a mixture of ethanol-methanol as retarders to carry out the gypsum setting. Natural Mexican gypsum samples and a hemihydrate prepared in the laboratory are used. The following analytical techniques are used: MO, DRX, DTA, TG and DTG. In agreement with the obtained results, it can be concluded: that colloid formation depends on the action of accelerators or retarders and the crystals are a consequence of the quantity of hemihydrate formed.

    En el mecanismo de hidratación y deshidratación del yeso existe la hipótesis de que éste se efectúa por dos fenómenos simultáneos. Este estudio intenta esclarecer estos fenómenos, empleando: cloruros como aceleradores o mezcla etanol-metanol como retardadores para efectuar el fraguado del yeso. Se emplean muestras de yeso de origen natural mexicano y hemihydrate preparado en laboratorio; se utilizan técnicas analíticas: MO, DRX, DTA, TG y DTG. De acuerdo a los resultados obtenidos se puede deducir: que la formación del coloide depende de la acción de los agentes aceleradores o retardadores y que los cristales son consecuencia de la cantidad de hemihidrato formado.

  19. Assessing dolomite surface reactivity at temperatures from 40 to 120 °C by hydrothermal atomic force microscopy

    Science.gov (United States)

    Berninger, Ulf-Niklas; Saldi, Giuseppe D.; Jordan, Guntram; Schott, Jacques; Oelkers, Eric H.

    2017-02-01

    This study investigated the reactivity of the (1 0 4) dolomite surface in the system MgCO3-CaCO3-NaCl-H2O via a suite of aqueous solution-dolomite hydrothermal atomic force microscopy interaction experiments at temperatures from 40 to 120 °C, pH ranging from 4 to 8, pressures up to 5 bars, and over a wide range of aqueous fluid saturation state. Dolomite dissolution was observed in the presence of undersaturated aqueous fluids. Dissolution produced crystallographically well defined etch pits, consistent with the stoichiometric release of ordered lattice cations. In low to moderately saturated fluids, dolomite growth began by the growth of one or two layers of carbonate (layer height dolomite surfaces at moderate rates, but these did not exhibit the characteristic dolomite crystallographic orientation after the growth of several layers. Taken together these observations suggest that the direct precipitation of dolomite from aqueous solution is disfavored at temperatures to at least 120 °C due to the poisoning of the dolomite surface for further growth by the precipitation of one to four Ca-Mg carbonate layers on these surfaces.

  20. STEM investigation of exsolution lamellae and "c" reflections in Ca-rich dolomite from the Platteville Formation, western Wisconsin

    CERN Document Server

    Shen, Zhizhang; Brown, Philip E; Xu, Huifang

    2016-01-01

    Dolomite crystals in partially dolomitized limestone from the Platteville Formation are both compositionally and microstructurally heterogeneous. A single dolomite crystal usually contains three phases: the host Ca-rich dolomite [Ca1.14Mg0.86(CO3)2], an Fe-bearing dolomite [Ca1.06Mg0.80Fe0.14(CO3)2], and calcite inclusions. These three phases show similar orientations. The Ca-rich dolomite exhibits modulated microstructures with wavelength ranging from 7 to 30 nm. The modulated microstructures are not evident in Fe-bearing dolomite. Modulations in the Ca-rich dolomite have three predominant orientation ranges in the studied sample: from (205) to (104), from (001) to (-101), and ~(110), which are consistent with previous studies. Bright-field (BF) and high-angle annular dark-field (HAADF) images confirm that these modulations are due to chemical variation rather than strain or diffraction contrast. The Ca-rich lamellae are Mg-rich calcite with compositions ranging from Ca0.85Mg0.15CO3 to Ca0.70Mg0.30CO3. The o...

  1. Spatial variations in the stoichiometry and geochemistry of Miocene dolomite from Grand Cayman: Implications for the origin of island dolostone

    Science.gov (United States)

    Ren, Min; Jones, Brian

    2017-03-01

    The Cayman Formation (Miocene), 140 m thick on Grand Cayman, is incompletely dolomitized with the most of the dolomite restricted to the peripheral part of the island. These calcium-rich dolomites, with 50-60 mol%CaCO3 (%Ca), are divided into low-calcium dolomite (LCD, %Ca 55%). Despite the small size of the island (6.8 km wide), the percentages of LCD and HCD, the %Ca, and the geochemical properties of the dolomites show geographic variations relative to the surrounding shelf edge. Accordingly, the Cayman Formation on the east end of the island is divided into the peripheral dolostone (shelf edge-1.5 km inland), transitional dolostone (1.5-2.7 km inland), and the interior limestone and dolostone (2.7 km to island center). From the peripheral dolostone to the interior limestone and dolostone, there is an increase in the percentage of HCD and %Ca in the dolomite, and decreases in the δ18O and δ13C values of the dolomite. Interpretations based on the oxygen and carbon isotopic compositions indicate that seawater is the source of Mg for dolomitization. The concentric pattern of dolomitization on the island reflects the fact that seawater flowed into the island from all directions during dolomitization. The lateral inland variations in the dolomite stoichiometric and isotopic properties reflect the gradual modification of seawater by water-rock interaction along the flow path from the shelf edge to the island center. 87Sr/86Sr ratios indicate that two phases of dolomitization (late Miocene-early Pliocene and late Pliocene-early Pleistocene) were responsible for dolomitization of the Cayman Formation. It is very likely that during both phases, the carbonate platform was subaerially exposed and that the pump for circulating the seawater through the island was related to the seawater/freshwater mixing zone. The dolomitization model developed from Grand Cayman may be applicable to many other island dolostones affected by long-term sea-level changes. Given that the

  2. Effect and mechanism of dolomite with different size fractions on hematite flotation using sodium oleate as collector

    Institute of Scientific and Technical Information of China (English)

    LUO Xi-mei; YIN Wan-zhong; WANG Yun-fan; SUN Chuan-yao; MA Ying-qiang; LIU Jian

    2016-01-01

    The effect of dolomite with different particle size fractions on hematite flotation was studied using sodium oleate as collector at pH of about 9. The effect mechanism of dolomite on hematite flotation was investigated by means of solution chemistry, ultraviolet spectrophotometry (UV), inductively coupled plasma atomic emission spectrometry (ICP-AES) and X-ray photoelectron spectroscopy (XPS). It is observed that dolomite with different size fractions has depressing effect on hematite flotation using sodium oleate as collector, and dolomite could be the "mineral depressant" of hematite using sodium oleate as collector. The reasons for that are concerned with sodium oleate consumption and the adsorption onto hematite of dissolved species of dolomite.

  3. Tetrahydrofuran hydrate decomposition characteristics in porous media

    Science.gov (United States)

    Song, Yongchen; Wang, Pengfei; Wang, Shenglong; Zhao, Jiafei; Yang, Mingjun

    2016-12-01

    Many tetrahydrofuran (THF) hydrate properties are similar to those of gas hydrates. In the present work THF hydrate dissociation in four types of porous media is studied. THF solution was cooled to 275.15 K with formation of the hydrate under ambient pressure, and then it dissociated under ambient conditions. THF hydrate dissociation experiments in each porous medium were conducted three times. Magnetic resonance imaging (MRI) was used to obtain images. Decomposition time, THF hydrate saturation and MRI mean intensity (MI) were measured and analyzed. The experimental results showed that the hydrate decomposition time in BZ-4 and BZ-3 was similar and longer than that in BZ-02. In each dissociation process, the hydrate decomposition time of the second and third cycles was shorter than that of the first cycle in BZ-4, BZ-3, and BZ-02. The relationship between THF hydrate saturation and time is almost linear.

  4. Influence of Lime and Phosphorus Application Rates on Growth of Maize in an Acid Soil

    Directory of Open Access Journals (Sweden)

    Peter Asbon Opala

    2017-01-01

    Full Text Available The interactive effects of lime and phosphorus on maize growth in an acid soil were investigated in a greenhouse experiment. A completely randomized design with 12 treatments consisting of four lime levels, 0, 2, 10, and 20 t ha−1, in a factorial combination with three phosphorus rates, 0, 30, and 100 kg ha−1, was used. Maize was grown in pots for six weeks and its heights and dry matter yield were determined and soils were analyzed for available P and exchangeable acidity. Liming significantly reduced the exchangeable acidity in the soils. The effect of lime on available P was not significant but available P increased with increasing P rates. There was a significant effect of lime, P, and P by lime interactions on plant heights and dry matter. Without lime application, dry matter increased with increasing P rates but, with lime, dry mattes increased from 0 to 30 kg P ha−1 but declined from 30 to 100 kg P ha−1. The highest dry matter yield (13.8 g pot−1 was obtained with a combined 2 t ha−1 of lime with 30 kg P ha−1 suggesting that lime application at low rates combined with moderate amounts of P would be appropriate in this soil.

  5. Repair mortars based on lime. Accelerated aging tests

    Directory of Open Access Journals (Sweden)

    Martínez-Ramírez, S.

    1995-06-01

    Full Text Available The behaviour under different accelerated aging tests (freeze/thaw and crystallization cycles of a new lime mortar with biocide properties destinated to monumental repair has been studied. New mortars (which have the biocide impregnated in a clay called sepiolite have a similar behaviour to lime mortars used as a reference. After the aging tests, the biocide properties of the mortars have been tried.

    Se ha estudiado el comportamiento frente a distintos ensayos de envejecimiento acelerado (ciclos de hielo/deshielo y cristalización de sales de un nuevo mortero de cal con propiedades biocidas, destinado a la reparación monumental. Se ha comprobado que los nuevos morteros (que llevan incorporado el biocida impregnado en una arcilla denominada sepiolita tienen un comportamiento muy similar a los morteros de cal utilizados como referencia. Tras los ensayos de envejecimiento se ha visto que las propiedades biocidas de los morteros se mantienen.

  6. OPTIMIZATION OF LIME PRETREATMENT FOR ENZYMATIC SACCHARIFICATION OF WHEAT STRAW

    Directory of Open Access Journals (Sweden)

    Miroslav Ondrejovič

    2014-02-01

    Full Text Available The aim of this work was optimization of lime pretreatment parameters such as temperature, time and reaction ratio to maximization of reducing saccharide yields occurred by enzyme hydrolysis of pretreated plant material (wheat straw. Pretreatment conditions were optimized using response surface methodology. The optimal conditions were chosen to promote reducing saccharide yields following enzymatic digestion and they were temperature 91.5 °C, time 2.4 hours and reaction ratio 19.7 mL to 1 g of treated wheat straw. The experimental values agreed with predicted within a 95 % confidence interval. The computed model of wheat straw pretreatment by lime can be used for the effective utilization of secondary products obtained in agriculture sector.

  7. Preparation and Metallurgical Analysis of High Activity Burnt Lime for Steelmaking

    Institute of Scientific and Technical Information of China (English)

    Hua-qiang HAO; Yu-zhu ZHANG; Su-ju HAO; Chao-fa ZHANG; Wu-feng JIANG; Peng-hui CUI

    2016-01-01

    Burnt lime is an important material in steelmaking and its activity degree is a key factor for liquid steel quality.The burnt lime was made by the calcination of limestone in a high pressure electric furnace.The burnt lime mineralogical phases and micro-morphologies were characterized by X-ray diffraction (XRD)and field emission scan-ning electron microscopy (FE-SEM).The burnt lime activity degree was determined by acid-base titration,the burnt lime pore distribution was measured by mercury intrusion porosimetry (MIP),and the thermal effect of a mixture of burnt lime and slag was measured by differential scanning calorimetry (DSC).The results showed that the CaO grain size and pore size of burnt lime made under high pressure were larger than those of burnt lime made under atmos-pheric pressure.The CaO grain size and pore size increased and the laminate phenomenon also occurred clearly under high pressure.The activity degree of burnt lime made under high pressure was greater than that made under atmos-pheric pressure.The maximum activity degree was 437 mL for burnt lime made under a pressure of 0.4 MPa.For the same ratio of CaO to SiO2 ,the melting temperature,hemisphere temperature and fluidity temperature of slag decreased with increasing burnt lime activity degree.The higher the activity degree the burnt lime had,the better the slag forming occurred.It was advantageous for 2CaO.SiO2 and 3CaO.SiO2 forming at lower temperatures if the burnt lime activity degree was increased.

  8. A Simple Ballistic Material Model for Soda-Lime Glass

    Science.gov (United States)

    2009-01-01

    for soda-lime glass devel- oped and parameterized in the previous sections is next imple- mented in a VUMAT Material User Subroutine of the commercial...each element. The essential features of the coupling between the ABAQUS/ Explicit finite-element solver and the VUMAT Material User Subroutine at...state as well as values of the material state variables at the end of the time increment are determined within the VUMAT and returned to the ABAQUS

  9. Between tradition and technological innovation: challenges to lime Heritage conservation

    Directory of Open Access Journals (Sweden)

    Marluci Menezes

    2016-01-01

    Full Text Available The aim is to discuss the relationship between traditional and scientific technological knowledge as innovative and fundamental to heritage conservation. It is argued that this innovation does not necessarily come from scientific knowledge, but potentially from a wise articulation between these two types of knowledge. This discussion starts from an already long process of reflection on lime heritage conservation, as developed in LNEC from research projects.

  10. Between tradition and technological innovation: challenges to lime Heritage conservation

    Directory of Open Access Journals (Sweden)

    Marluci Menezes

    2016-01-01

    Full Text Available The aim is to discuss the relationship between traditional and scientific technological knowledge as innovative and fundamental to heritage conservation. It is argued that this innovation does not necessarily come from scientific knowledge, but potentially from a wise articulation between these two types of knowledge. This discussion starts from an already long process of reflection on lime heritage conservation, as developed in LNEC from research projects.

  11. Improvement in hardness of soda-lime-silica glass

    Science.gov (United States)

    Chakraborty, Riya; De, Moumita; Roy, Sudakshina; Dey, Arjun; Biswas, Sampad K.; Middya, Tapas Ranjan; Mukhopadhyay, Anoop K.

    2012-06-01

    Hardness is a key design parameter for structural application of brittle solids like glass. Here we report for the first time the significant improvement of about 10% in Vicker's hardness of a soda-lime-silica glass with loading rate in the range of 0.1-10 N.s-1. Corroborative dark field optical and scanning electron microscopy provided clue to this improvement through evidence of variations in spatial density of shear deformation band formation as a function of loading rate.

  12. Impact of anthropogenic induced nitrogen input and liming on phosphorous leaching in forest soils

    Science.gov (United States)

    Holzmann, Stefan; Puhlmann, Heike; Wilpert, Klaus

    2016-04-01

    Introduction: Phosphorous (P) is essential for sustainable forest growth, yet the impact of anthropogenic impacts on P leaching losses from forest soils are hardly known. Methods: We conducted an irrigation experiment with 128 mesocosms of 7.4 cm diameter containing 20 cm mineral soil plus the organic layer from three forest sites representing a gradient of resin extractable P of the A-horizon. On each site we selected a Fagus sylvatica and a Picea abies managed subsite. Half of the cylinders where planted with seedlings of the respective species to access the plant impact. We simulated ambient rain (AR), anthropogenic nitrogen input (NI) of 100 kg/ha/a and forest liming (FL) with a dolomite input of 0.3 Mg/ha/a. Soil solution was extracted from the organic layer and at 20 cm depth. We collected the soil solution over a period of 13.5 months and analyzed it separated by 5 periods. The soil solution was analyzed for total phosphorous (TP) by measuring the molybdane reactive phosphorous after acid digestion. To analyze the multivariate dataset we applied random forest modelling and used partial (co-)dependency plots to interpret the results. Results: The TP content of the soil solution from the organic horizon was approximately ten times higher than the soil solution content of the mineral soil. The NI treatment did increase the TP content on all sites. The increase was more pronounced in the organic layer than in the mineral layer. The FL treatment lead to a slight increase of TP in the organic layer while we could observe a slight decrease in the mineral horizon. Both the organic layer and the mineral horizon showed a seasonal cycle with the exception of one Picea abies subsite which displayed a constant increase in TP in the organic layer. The seasonal cycle of the organic horizon had a minimum during the period of April to July, while the minimum at the mineral horizon was during November to January. Conclusion: TP in the soil solution is highest in the organic

  13. Simply Understanding of Lacustrine Dolomite%对白云岩形成机理的再认识

    Institute of Scientific and Technical Information of China (English)

    蔡雪峰; 闫志为; 夏源

    2016-01-01

    Dolomite usually can form one of the best oil and gas accumulation in carbonate. Multiresolution is directly de-termined by the understanding of genetic evolution and reservoir spatial distribution of dolomite. However the origin of dolomite is quite complex and difficult to solve in long term in the domain of carbonate petrology. According to the different mechanism, all the current main dolomite can be classified into two styles:primary dolomites and secondary dolomites. Whether they be-long to the real primary dolomites still needs further research,large numbers of primary dolomites have been found. It is par-ticularly important for the understanding of dolomite and carbonate reservoirs for oil and gas exploration to clarify the origin of dolomite.%在碳酸盐岩体系中,白云岩通常能形成最好的储层.对白云岩成因演化和储层展布的认识直接决定勘探部署.而白云岩成因是碳酸盐岩岩石学中最复杂、争论时间最久、最难解决的问题之一.根据机理的不同,当前各种主要的白云岩成因模式可划分为两大类:原生白云石模式和次生白云石化模式.虽然原生白云石的例子已被大量发现,但它们是否属真正的原生白云石仍需后续研究;理清白云岩成因问题,对认识白云岩及其相关的碳酸盐岩储层的油气勘探工作尤为重要.

  14. Flavor chemistry of lemon-lime carbonated beverages.

    Science.gov (United States)

    Hausch, Bethany J; Lorjaroenphon, Yaowapa; Cadwallader, Keith R

    2015-01-14

    The most potent aroma-active components of Sprite (SP), Sierra Mist (SM), and 7UP (7UP) were identified. Aroma extracts were prepared by liquid–liquid continuous extraction/solvent-assisted flavor evaporation (LLCE/SAFE). Twenty-eight compounds were detected by gas chromatography–olfactometry (GC-O) with linalool (floral, lavender), octanal (pungent orange), and 2,3-dehydro-1,8-cineole (minty) determined to be predominant aroma compounds based on their high flavor dilution (FD) factors by aroma extract dilution analysis (AEDA). The data indicate that lemon-lime flavor is composed of a small number of compounds (22 at the most in SM), and only a subset of these may be important because many compounds were detected only at low FD factors. Predominant aroma compounds (23) were quantified using static headspace solid phase microextraction (SPME) combined with stable isotope dilution assays (SIDA). In contrast to FD factors, the calculated odor-activity values (OAVs) indicate that octanal and limonene make the greatest contribution to the overall aroma of lemon-lime carbonated beverages, followed by nonanal, decanal, linalool, 1,8-cineole, and geranyl acetate. The results demonstrate that lemon-lime carbonated beverages share many of the same compounds but the relative abundance of these compounds varies by brand.

  15. Thermophysical properties of hydrophobised lime plasters - The influence of ageing

    Science.gov (United States)

    Pavlíková, Milena; Zemanová, Lucie; Pavlík, Zbyšek

    2017-07-01

    The building envelope is a principal responsible for buildings energy loses. Lime plasters as the most popular finishing materials of historical buildings and culture monuments influence the thermal behaviour as well as construction material of masonry. On this account, the effect of ageing on the thermophysical properties of a newly designed lime plasters containing hydrophobic admixture is analysed in the paper. For the comparative purposes, the reference lime plaster is tested. The ageing is accelerated with controlled carbonation process to simulate the final plasters properties. Basic characterization of the tested materials is done using bulk density, matrix density, and porosity measurements. Thermal conductivity and volumetric heat capacity are experimentally assessed using a transient impulse method. The obtained data revealed the significant changes of the both studied thermal parameters in the dependence on plasters composition and age. The assessed material parameters will be stored in a material database, where will find use as an input data for computational modelling of heat transport in this type of porous building materials and evaluation of energy-savings and sustainability issues.

  16. Speciation of aluminium, arsenic and molybdenum in excessively limed lakes.

    Science.gov (United States)

    Sjöstedt, Carin; Wällstedt, Teresia; Gustafsson, Jon Petter; Borg, Hans

    2009-09-01

    The possible existence of the potentially toxic oxyanions of Al (Al(OH)(4)(-)), As (HAsO(4)(2-)), and Mo (MoO(4)(2-)) was examined in excessively limed lakes. In-situ dialysis (MWCO 1 kDa) was performed in the surface and bottom waters of two excessively limed lakes (pH 7.1-7.7) and one acidic lake (pH approximately 5.4). The dialysable metal concentrations were compared to the equilibrium distribution of species as calculated with the geochemical code Visual MINTEQ incorporating the CD-MUSIC and Stockholm Humic models for complexation onto colloidal ferrihydrite and dissolved organic matter. Arsenic and molybdenum in the excessively limed lakes were to a large extent present in the dialysable fraction (>79% and >92% respectively). They were calculated to exist as free or adsorbed oxyanions. Most of the Al was observed to reside in the colloidal fraction (51-82%). In agreement with this, model predictions indicated aluminium to be present mostly as colloids or bound to dissolved organic matter. Only a small fraction was modelled as Al(OH)(4)(-) ions. In most cases, modelled values were in agreement with the dialysis results. The free concentrations of the three oxyanions were mostly low compared to toxic levels.

  17. Speciation of aluminium, arsenic and molybdenum in excessively limed lakes

    Energy Technology Data Exchange (ETDEWEB)

    Sjoestedt, Carin, E-mail: carinsj@kth.se [Department of Land and Water Resources Engineering, KTH (Royal Institute of Technology), Teknikringen 76, SE-100 44 Stockholm (Sweden); Waellstedt, Teresia [Department of Aquatic Sciences and Assessment, SLU (Swedish University of Agricultural Sciences), P.O. Box 7050, SE-750 07 Uppsala (Sweden); Gustafsson, Jon Petter [Department of Land and Water Resources Engineering, KTH (Royal Institute of Technology), Teknikringen 76, SE-100 44 Stockholm (Sweden); Borg, Hans [Department of Applied Environmental Science, SU (Stockholm University), SE-106 91 Stockholm (Sweden)

    2009-09-01

    The possible existence of the potentially toxic oxyanions of Al (Al(OH){sub 4}{sup -}), As (HAsO{sub 4}{sup 2-}), and Mo (MoO{sub 4}{sup 2-}) was examined in excessively limed lakes. In-situ dialysis (MWCO 1 kDa) was performed in the surface and bottom waters of two excessively limed lakes (pH 7.1-7.7) and one acidic lake (pH {approx} 5.4). The dialysable metal concentrations were compared to the equilibrium distribution of species as calculated with the geochemical code Visual MINTEQ incorporating the CD-MUSIC and Stockholm Humic models for complexation onto colloidal ferrihydrite and dissolved organic matter. Arsenic and molybdenum in the excessively limed lakes were to a large extent present in the dialysable fraction (> 79% and > 92% respectively). They were calculated to exist as free or adsorbed oxyanions. Most of the Al was observed to reside in the colloidal fraction (51-82%). In agreement with this, model predictions indicated aluminium to be present mostly as colloids or bound to dissolved organic matter. Only a small fraction was modelled as Al(OH){sub 4}{sup -} ions. In most cases, modelled values were in agreement with the dialysis results. The free concentrations of the three oxyanions were mostly low compared to toxic levels.

  18. Clinker mineral hydration at reduced relative humidities

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Hansen, Per Freiesleben; Lachowski, Eric E.;

    1999-01-01

    Vapour phase hydration of purl cement clinker minerals at reduced relative humidities is described. This is relevant to modern high performance concrete that may self-desiccate during hydration and is also relevant to the quality of the cement during storage. Both the oretical considerations...... and experimental data are presented showing that C(3)A can hydrate at lower humidities than either C3S or C2S. It is suggested that the initiation of hydration during exposure to water vapour is nucleation controlled. When C(3)A hydrates at low humidity, the characteristic hydration product is C(3)AH(6...

  19. Progress of Gas Hydrate Studies in China

    Institute of Scientific and Technical Information of China (English)

    樊栓狮; 汪集旸

    2006-01-01

    A brief overview is given on the gas hydrate-related research activities carried out by Chinese researchers in the past 15 years. The content involves: (1) Historical review. Introducing the gas hydrate research history in China; (2) Gas hydrate research groups in China. There are nearly 20 groups engaged in gas hydrate research now; (3) Present studies.Including fundamental studies, status of the exploration of natural gas hydrate resources in the South China Sea region, and development of hydrate-based new techniques; (4) Future development.

  20. Experimental Simulation of Dolomite Dissolution Under Burial Diagenesis Conditions and Thermodynamic Interpretation

    Institute of Scientific and Technical Information of China (English)

    黄思静; 肖林萍; 等

    2000-01-01

    Simulating experiments on dolomite dissolution by acetic acid were made under burial diagenesis conditions,at temperatures ranging from 75℃to 130℃ and pressures from 20 MPA to 30MPa,The results show that the dissolution rate of dolomite increased rapidly with increasing temperature and prssure,From 75℃/Mpa to 130℃/30 MPa,the total amount of released ca and Mg increased from 32.98mg/L to 337.9mg/L,over one order of magnitude in difference,Thermodynamic calculation indicates that the increment of Gibbs free energy (ΔG) of the chemical reaction decreases with increasing temperature and pressure.This thermodynamic result is consistent with the experimental result.Based on the Experimental results.it is suggested that secondary prosities formed by dolomite dissolution under conditions of deep burial diagenesis should be more common than those under epigenesis and shallow burial conditions,and therefore dolomite reservoires in the formations that have been deeply buried should be more abundant than in the formations that have only been shallowly buried.

  1. Greenhouse conditions induce mineralogical changes and dolomite accumulation in coralline algae on tropical reefs.

    Science.gov (United States)

    Diaz-Pulido, Guillermo; Nash, Merinda C; Anthony, Kenneth R N; Bender, Dorothea; Opdyke, Bradley N; Reyes-Nivia, Catalina; Troitzsch, Ulrike

    2014-01-01

    Human-induced ocean acidification and warming alter seawater carbonate chemistry reducing the calcification of reef-building crustose coralline algae (CCA), which has implications for reef stability. However, due to the presence of multiple carbonate minerals with different solubilities in seawater, the algal mineralogical responses to changes in carbonate chemistry are poorly understood. Here we demonstrate a 200% increase in dolomite concentration in living CCA under greenhouse conditions of high pCO2 (1,225 μatm) and warming (30 °C). Aragonite, in contrast, increases with lower pCO2 (296 μatm) and low temperature (28 °C). Mineral changes in the surface pigmented skeleton are minor and dolomite and aragonite formation largely occurs in the white crust beneath. Dissolution of high-Mg-calcite and particularly the erosive activities of endolithic algae living inside skeletons play key roles in concentrating dolomite in greenhouse treatments. As oceans acidify and warm in the future, the relative abundance of dolomite in CCA will increase.

  2. Colloid transport in dolomite rock fractures: effects of fracture characteristics, specific discharge, and ionic strength.

    Science.gov (United States)

    Mondal, Pulin K; Sleep, Brent E

    2012-09-18

    The effects of fracture characteristics, specific discharge, and ionic strength on microsphere transport in variable-aperture dolomite rock fractures were studied in a laboratory-scale system. Fractures with different aperture distributions and mineral compositions were artificially created in two dolomite rock blocks. Transport tests were conducted with bromide and carboxylate-modified latex microspheres (20, 200, and 500 nm diameter). Under overall unfavorable attachment conditions, there was significant retention of the 20 nm microsphere and minimal retention of the 500 nm microsphere for all conditions examined. Aperture variability produced significant spatial variation in colloid transport. Flushing with low ionic strength solution (1 mM) following microsphere transport at 12 mM ionic strength solution produced a spike in effluent microsphere concentrations, consistent with retention of colloids in secondary energy minima. Surface roughness and charge heterogeneity effects may have also contributed to the effect of microsphere size on retention. Matrix diffusion influenced bromide transport but was not a dominant factor in transport for any microsphere size. Calibrated one-dimensional, two-site kinetic model parameters for colloid transport in fractured dolomite were sensitive to the physical and chemical properties of both the fractured dolomite and the colloids, indicating the need for mechanistic modeling for accurate prediction.

  3. Greenhouse conditions induce mineralogical changes and dolomite accumulation in coralline algae on tropical reefs

    Science.gov (United States)

    Diaz-Pulido, Guillermo; Nash, Merinda C.; Anthony, Kenneth R. N.; Bender, Dorothea; Opdyke, Bradley N.; Reyes-Nivia, Catalina; Troitzsch, Ulrike

    2014-02-01

    Human-induced ocean acidification and warming alter seawater carbonate chemistry reducing the calcification of reef-building crustose coralline algae (CCA), which has implications for reef stability. However, due to the presence of multiple carbonate minerals with different solubilities in seawater, the algal mineralogical responses to changes in carbonate chemistry are poorly understood. Here we demonstrate a 200% increase in dolomite concentration in living CCA under greenhouse conditions of high pCO2 (1,225 μatm) and warming (30 °C). Aragonite, in contrast, increases with lower pCO2 (296 μatm) and low temperature (28 °C). Mineral changes in the surface pigmented skeleton are minor and dolomite and aragonite formation largely occurs in the white crust beneath. Dissolution of high-Mg-calcite and particularly the erosive activities of endolithic algae living inside skeletons play key roles in concentrating dolomite in greenhouse treatments. As oceans acidify and warm in the future, the relative abundance of dolomite in CCA will increase.

  4. Model study of initial adsorption of SO{sub 2} on calcite and dolomite

    Energy Technology Data Exchange (ETDEWEB)

    Malaga-Starzec, Katarina; Panas, Itai; Lindqvist, Oliver

    2004-01-30

    The rate of calcareous stone degradation is to a significant extent controlled by their surface chemistry with SO{sub 2}. Initial surface sulphite is converted to a harmful gypsum upon, e.g. NO{sub 2} catalysed oxidation. However, it has been observed by scanning electron microscopy that the lateral distributions of gypsum crystals differ between calcitic and dolomitic marbles. The first-principles density functional theory is employed to understand the origin of these fundamentally different morphologies. Here, the stability differences of surface sulphite at calcite CaCO{sub 3} (s) and dolomite Ca{sub x}Mg{sub 1-x}CO{sub 3} (s) are determined. A qualitative difference in surface sulphite stability, favouring the former, is reported. This is taken to imply that calcitic micro-crystals embedded in a dolomitic matrix act as sinks in the surface sulphation process, controlled by SO{sub 2} diffusion. The subsequent formation of gypsum under such conditions will not require SO{sub 4}{sup 2-} (aq) ion transport. This explains the homogeneous distribution of gypsum observed on the calcitic micro-crystals in dolomite. In contrast, sulphation on purely calcitic marbles never reaches such high SO{sub 2} coverage. Rather, upon oxidation, SO{sub 4}{sup 2-} (aq) transport to nucleation centres, such as grain boundaries, is required for the growth of gypsum crystals.

  5. Deep karstified dolomite aquifer as a source of drinking water - isotopic measurements

    Science.gov (United States)

    Bracic Zeleznik, Branka; Cencur Curk, Barbara; Zvab Rozic, Petra; Torkar, Anja; Vreca, Polona; Brencic, Mihael

    2017-04-01

    The Ljubljana Moor extends from the southern part of Ljubljana, the capital of Slovenia, to Krim-Mokrc karstic mountains. The sedimentation basin of Ljubljana Moor is filled up in the central part with lacustrine and marshy sediments and on the borders of the basin are the gravel fans. In the base of sedimentation basin is prequaternary karstified upper triasic dolomite. Ljubljana Moor aquifer is one of the biggest and very important drinking water sources in the central part of Slovenia. The water field Brest with 13 wells is situated in southern part of Moor, on I\\vska fan. The wells of different depth, from 28 m to 200 m, pump groundwater from various geological units, quaternary sediments and karstified dolomite. The land use on recharge area is agriculture and urbanization and in the last decade we monitor the deterioration of groundwater quality in quaternary sediments. In 2011 the 200 m deep well (VD Brest-3a) was drilled to catch the groundwater better quality in triasic dolomite that is in hydraulic connection with the karstic area in hinterland. To determine the recharge dynamic, origin and age of groundwater in dolomite, we provide several isotopic samplings on different depths. We measured oxygen (δ18O), deuterium (δ2H) and inorganic carbon (δ13CDIC). .

  6. Hydration of fly ash cement

    Energy Technology Data Exchange (ETDEWEB)

    Etsuo Sakai; Shigeyoshi Miyahara; Shigenari Ohsawa; Seung-Heun Lee; Masaki Daimon [Tokyo Institute of Technology, Tokyo (Japan). Department of Metallurgy and Ceramics Science, Graduate School of Science and Engineering

    2005-06-01

    It is necessary to establish the material design system for the utilization of large amounts of fly ash as blended cement instead of disposing of it as a waste. Cement blended with fly ash is also required as a countermeasure to reduce the amount of CO{sub 2} generation. In this study, the influences of the glass content and the basicity of glass phase on the hydration of fly ash cement were clarified and hydration over a long curing time was characterized. Two kinds of fly ash with different glass content, one with 38.2% and another with 76.6%, were used. The hydration ratio of fly ash was increased by increasing the glass content in fly ash in the specimens cured for 270 days. When the glass content of fly ash is low, the basicity of glass phase tends to decrease. Reactivity of fly ash is controlled by the basicity of the glass phase in fly ash during a period from 28 to 270 days. However, at an age of 360 days, the reaction ratios of fly ash show almost identical values with different glass contents. Fly ash also affected the hydration of cement clinker minerals in fly ash cement. While the hydration of alite was accelerated, that of belite was retarded at a late stage.

  7. U-Pb dating of speleogenetic dolomite: A new sulfuric acid speleogenesis chronometer

    Directory of Open Access Journals (Sweden)

    Victor Polyak

    2016-05-01

    Full Text Available The 1100-meter Big Room elevation level of Carlsbad Cavern, New Mexico USA, formed 4 Ma by hypogenic sulfuric acid speleogenesis (SAS. The age of the Big Room level of 4.0 ± 0.2 Ma was previously determined by dating alunite, a byproduct of speleogenesis, using the 40Ar/39Ar method. Duplication of these results is possible by radiometric dating of other byproducts interpreted to be speleogenetic (a byproduct of speleogenesis such as calcite and dolomite in certain settings. XRD and TEM analyses of sample 94044, a piece of crust collected within the Big Room level of SAS just below Left Hand Tunnel indicate that this dolomite sample we interpret to be speleogenetic is as well-ordered crystallographically as the Permian bedrock dolomite, possibly reflecting its SAS origin. Three U-Pb analyses were performed on subsamples A1, A2, and A3 of sample 94044, and two, A1 & A2, produced out-of-secular equilibrium results due to the presence of authigenic quartz and/or later re-distribution of uranium in the dolomite crust, which prevented the calculation of an isochron age. Because subsample 94044-A3 exhibited δ234U and 230Th/238U values consistent with secular equilibrium, we were able to generate a 238U/204Pb-206Pb/204Pb model age of 4.1 ± 1.3 Ma on the dolomite crust (94044 that we interpret to be reliable. The 4.1 Ma age of the speleogenetic dolomite crust agrees with the 4 Ma 40Ar/39Ar age for the timing of speleogenesis of the Big Room level. While 40Ar/39Ar-dating of speleogenetic alunite- and jarosite-group minerals remains the primary way to determine absolute timing of hypogenic SAS, here we demonstrate that U-Pb dating of speleogenetic dolomite can be used to compliment or independently measure the timing of SAS. This method of dating SAS could be applicable in caves where the more soluble SAS-indicator minerals such as gypsum, alunite, and jarosite have been removed.

  8. Liming impacts on soils, crops and biodiversity in the UK: A review.

    Science.gov (United States)

    Holland, J E; Bennett, A E; Newton, A C; White, P J; McKenzie, B M; George, T S; Pakeman, R J; Bailey, J S; Fornara, D A; Hayes, R C

    2017-08-11

    Fertile soil is fundamental to our ability to achieve food security, but problems with soil degradation (such as acidification) are exacerbated by poor management. Consequently, there is a need to better understand management approaches that deliver multiple ecosystem services from agricultural land. There is global interest in sustainable soil management including the re-evaluation of existing management practices. Liming is a long established practice to ameliorate acidic soils and many liming-induced changes are well understood. For instance, short-term liming impacts are detected on soil biota and in soil biological processes (such as in N cycling where liming can increase N availability for plant uptake). The impacts of liming on soil carbon storage are variable and strongly relate to soil type, land use, climate and multiple management factors. Liming influences all elements in soils and as such there are numerous simultaneous changes to soil processes which in turn affect the plant nutrient uptake; two examples of positive impact for crops are increased P availability and decreased uptake of toxic heavy metals. Soil physical conditions are at least maintained or improved by liming, but the time taken to detect change varies significantly. Arable crops differ in their sensitivity to soil pH and for most crops there is a positive yield response. Liming also introduces implications for the development of different crop diseases and liming management is adjusted according to crop type within a given rotation. Repeated lime applications tend to improve grassland biomass production, although grassland response is variable and indirect as it relates to changes in nutrient availability. Other indicators of liming response in grassland are detected in mineral content and herbage quality which have implications for livestock-based production systems. Ecological studies have shown positive impacts of liming on biodiversity; such as increased earthworm abundance that

  9. The formation of lacustrine dolomites: an example from the Tortonian-Messinian sequence at the East Mediterranean margins (northern Israel)

    Science.gov (United States)

    Shaked Gelband, Dotan; Starinsky, Abraham; Stein, Mordechai

    2017-04-01

    Lacustrine water bodies that filled the tectonic depressions in the Lower Galilee area of Israel during the Tortonian-Messinian periods deposited Bira and Gesher Formations, which comprise marly limestones and dolomites, basalts, and varying amounts of mollusc fossils. Most fossils are gastropods of fresh to brackish water origin, while marine representation is minor and comprise monospecific assemblages of euryhaline bivalves. During the deposition of the Tortonian Bira formation the lakes were mostly influenced by meteoric waters while during the deposition of the Messinian Gesher Formation they became more swampy. Here, we set to establish the deposition conditions of the dolomites in the lacustrine formations. The following petrographic characteristics indicate dolomitization of precursor carbonate sediment during early diagenesis stage: (1) Dolomitized fossils with similar texture as the surrounding dolomite matrix; (2) Common euhedral inner zone crystals, representing original growth in solution or plastic environment; (3) Subhedral outer shape derived from neighboring crystals collisions. More information is given by the δ18O and δ13C values of the dolomites. The δ18O of the inter-layered limestones and dolomites fluctuates between -3‰ to -4‰ (VPDB) in the limestones and +5‰ to -1.5‰ (VPDB) in the adjacent dolomites. These fluctuations are prominent in the Bira formation and become smaller along the sequence with the decrease in the dolomite values. δ13C values of both limestones and dolomites gradually decrease along the stratigraphic section, from -3.5‰ to -10‰ (VPDB) in the limestones, and from 0‰ to -8‰ (VPDB) in the dolomites. The data suggest a dolomitization process controlled by the following events: 1. Evaporation of fresh lake waters originated from the surrounding environment as runoff. It should be emphasized that significant evaporation could take place only in terminal lakes, during periods of relatively dry climate with low

  10. The effect of electrolytes on dolomite dissolution: nanoscale observations using in situ Atomic Force Microscopy

    Science.gov (United States)

    Urosevic, Maja; Ruiz-Agudo, Encarnacion; Putnis, Christine V.; Cardell, Carolina; Rodriguez-Navarro, Carlos; Putnis, Andrew

    2010-05-01

    Dissolution of carbonate minerals is one of the main chemical reactions occurring at shallow levels in the crust of the Earth and has a paramount importance for a wide range of geological and biological processes. Calcite (CaCO3), and to a lesser extent dolomite (CaMg(CO3)2), are the major carbonate minerals in sedimentary rocks and building stone materials. The dissolution of calcite has been thoroughly investigated over a range of conditions and solution compositions. In contrast, dolomite dissolution studies have been traditionally hampered by its low reaction rates compared to calcite and its poorly constrained relationship between cation ordering and reactivity (Morse and Arvidson, 2002). Yet important questions like the so-called 'dolomite problem' (e.g. Higgins and Hu, 2005) remain unresolved and more experimental work is needed in order to understand the role of other dissolved species, such as soluble salts, on the kinetics and mechanism of dolomite dissolution and precipitation. We have explored the effect of different electrolytes on the dissolution rate of dolomite by using in situ Atomic Force Microcopy (AFM). Experiments were carried out by passing alkali halide, nitrate and sulfate salt solutions (NaCl, KCl, LiCl, NaI, NaNO3 and Na2SO4) with different ionic strengths (IS = 10-3, 10-2 and 10-1) over dolomite {1014} cleavage surfaces. We show that all electrolytes tested enhance dolomite dissolution. Moreover, the morphology and density of etch pits are controlled by the presence of different ions in solution. The etch pit spreading rate and dolomite dissolution rate depend on both (1) the nature of the electrolyte and (2) the ionic strength. This is in agreement with recent experimental studies on calcite dissolution (Ruiz-Agudo et al., 2010). This study highlights the role of electrolytes in dolomite dissolution and points to a common behavior for carbonate minerals. Our results suggest that soluble salts may play a critical role in the weathering of

  11. Comparison of stromal hydration techniques for clear corneal cataract incisions: conventional hydration versus anterior stromal pocket hydration.

    Science.gov (United States)

    Mifflin, Mark D; Kinard, Krista; Neuffer, Marcus C

    2012-06-01

    Anterior stromal pocket hydration was compared with conventional hydration for preventing wound leak after 2.8 mm uniplanar clear corneal incisions (CCIs) in patients having routine cataract surgery. Conventional hydration involves hydration of the lateral walls of the main incision with visible whitening of the stroma. The anterior stromal pocket hydration technique involves creation of an additional supraincisional stromal pocket overlying the main incision, which is then hydrated instead of the main incision. Sixty-six eyes of 48 patients were included in the data analysis with 33 assigned to each study group. The anterior stromal pocket hydration technique was significantly better than conventional hydration in preventing wound leak due to direct pressure on the posterior lip of the incision. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  12. Gas hydrates forming and decomposition conditions analysis

    Directory of Open Access Journals (Sweden)

    А. М. Павленко

    2017-07-01

    Full Text Available The concept of gas hydrates has been defined; their brief description has been given; factors that affect the formation and decomposition of the hydrates have been reported; their distribution, structure and thermodynamic conditions determining the gas hydrates formation disposition in gas pipelines have been considered. Advantages and disadvantages of the known methods for removing gas hydrate plugs in the pipeline have been analyzed, the necessity of their further studies has been proved. In addition to the negative impact on the process of gas extraction, the hydrates properties make it possible to outline the following possible fields of their industrial use: obtaining ultrahigh pressures in confined spaces at the hydrate decomposition; separating hydrocarbon mixtures by successive transfer of individual components through the hydrate given the mode; obtaining cold due to heat absorption at the hydrate decomposition; elimination of the open gas fountain by means of hydrate plugs in the bore hole of the gushing gasser; seawater desalination, based on the hydrate ability to only bind water molecules into the solid state; wastewater purification; gas storage in the hydrate state; dispersion of high temperature fog and clouds by means of hydrates; water-hydrates emulsion injection into the productive strata to raise the oil recovery factor; obtaining cold in the gas processing to cool the gas, etc.

  13. Comparison of Amberlite IR 120 and dolomite's performances for removal of heavy metals.

    Science.gov (United States)

    Kocaoba, Sevgi

    2007-08-17

    The presence of heavy metals in the environment is major concern due to their toxicity. Contamination of heavy metals in water supplies has steadily increased over the last years as a result of over population and expansion of industrial activities. A strong cation-exchange resin, Amberlite IR 120 and a natural zeolite, dolomite were used for the removal of lead(II) and cadmium(II). The optimum conditions were determined in a batch system as concentration range was between 5 and 100 mg/L, pH range between 1 and 8, contact time between 5 and 90 min, and the amount of adsorbent was from 0.1 to 1g. A constant stirring speed, 2000 rpm, was chosen during all of the experiments. The optimum conditions were found to be a concentration of 20 mg/L, pH of 5, contact time of 60 min and 0.5 g of adsorbent. Also, for investigation of exchange equilibria different amounts of ion exchange resin and dolomite were contacted with a fixed volume and concentration of a heavy metal bearing solutions. Sorption data have been interpreted in terms of Langmuir and Freundlich equations. The effect of adsorption temperature on the heavy metals adsorption onto dolomite was investigated at three different temperatures (20, 40 and 60 degrees C). Thermodynamic parameters were calculated. The results obtained show that the Amberlite IR 120 strong cation-exchange resin and dolomite performed well for the removal of these heavy metals. As a low cost adsorbent, dolomite can preferable for removal of heavy metals from wastewaters.

  14. Important geosites and parks in the UNESCO World Heritage Site of the Dolomites

    Energy Technology Data Exchange (ETDEWEB)

    Nossing, L.; Forti, S.

    2016-10-01

    In the geological complexity of the south Tyrol, the Dolomites play a fundamental role, as they are now included in the UNESCO World Heritage (2009) because of their exceptional beauty and unique landscape, together with numerous scientific discoveries. The name of Dolomite comes from the famous mineral dolomite (double calcium magnesium carbonate) discovered by Déodat De Dolomieu in 1789. The dolomitic rocks constitute a large area of the Triassic mountains and many studies have contributed to the discovery of the fundamental stratotypes for the signature of the Permian/Triassic boundary. The steep walls of the Permian volcanic formations and the Sciliar Mountain have always been a great attraction for scientists from all over the world to study the open book of nature in the Dolomites. We will illustrate three sites: 1. The Bula Geotrail. A geological trail through one of the best-preserved sedimentary series in which we can observe one of the most important stratotypes to touch the Permian/Triassic boundary. 2. The Siusi-Alpe di Siusi Geological Trail. This trail starts just above the Permian/Triassic boundary and is characterized by some unique basaltic columnar formations and other significant outcrops of Lower and Medium Triassic. 3. The Bletterbach Geopark. In this sequence the stratotype, which represents the boundary, is a dark coloured continuous layer (organic matter) 5cm thick, and contains some paleobotanical evidence which is unique in the world. The preservation and added value of the natural and geological patrimony of a region through guided and documented trails are at the origin of a new kind of tourism: geotourism. The modern tourist is more and more interested and stimulated by getting to knowing nature in depth. The trails are the best instruments for scientific divulgation and education, allowing a better understanding of the landscape and stimulating new discoveries. (Author)

  15. Comparison of Amberlite IR 120 and dolomite's performances for removal of heavy metals

    Energy Technology Data Exchange (ETDEWEB)

    Kocaoba, Sevgi [Yildiz Technical University, Faculty of Art and Science, Department of Chemistry, Davutpasa Cad. No: 127, 34210 Davutpasa, Istanbul (Turkey)]. E-mail: kocaoba@yildiz.edu.tr

    2007-08-17

    The presence of heavy metals in the environment is major concern due to their toxicity. Contamination of heavy metals in water supplies has steadily increased over the last years as a result of over population and expansion of industrial activities. A strong cation-exchange resin, Amberlite IR 120 and a natural zeolite, dolomite were used for the removal of lead(II) and cadmium(II). The optimum conditions were determined in a batch system as concentration range was between 5 and 100 mg/L, pH range between 1 and 8, contact time between 5 and 90 min, and the amount of adsorbent was from 0.1 to 1 g. A constant stirring speed, 2000 rpm, was chosen during all of the experiments. The optimum conditions were found to be a concentration of 20 mg/L, pH of 5, contact time of 60 min and 0.5 g of adsorbent. Also, for investigation of exchange equilibria different amounts of ion exchange resin and dolomite were contacted with a fixed volume and concentration of a heavy metal bearing solutions. Sorption data have been interpreted in terms of Langmuir and Freundlich equations. The effect of adsorption temperature on the heavy metals adsorption onto dolomite was investigated at three different temperatures (20, 40 and 60 deg. C). Thermodynamic parameters were calculated. The results obtained show that the Amberlite IR 120 strong cation-exchange resin and dolomite performed well for the removal of these heavy metals. As a low cost adsorbent, dolomite can preferable for removal of heavy metals from wastewaters.

  16. [Study on the traditional lime mortar from the memorial archway in the southern Anhui province].

    Science.gov (United States)

    Wei, Guo-Feng; Sun, Sheng; Wang, Cheng-Xing; Zhang, Bing-Jian; Chen, Xi-Min

    2013-07-01

    The traditional lime mortar was investigated by means of scanning electron microscope (SEM), X-ray diffractometry and Fourier transform infrared spectrometry (FTIR). The results show that the mortar from the memorial archway in the southern Anhui province was the organic-inorganic composite materials composed of lime with tung oil or sticky rice. It was found that the excellent performance of the tung oil-lime mortar can be explained by the compact lamellar organic-inorganic composite structure that was produced by carbonization reaction of lime, cross-linking reactions of tung oil and oxygen and complexing reaction of Ca2+ and -COO-. The compact micro-structure of sticky rice-lime mortar, which was produced due to carbonation process of lime controlled by amylopectin, should be the cause of the good performance of this kind of organic-inorganic mortar.

  17. Models for predicting the mass of lime fruits by some engineering properties.

    Science.gov (United States)

    Miraei Ashtiani, Seyed-Hassan; Baradaran Motie, Jalal; Emadi, Bagher; Aghkhani, Mohammad-Hosein

    2014-11-01

    Grading fruits based on mass is important in packaging and reduces the waste, also increases the marketing value of agricultural produce. The aim of this study was mass modeling of two major cultivars of Iranian limes based on engineering attributes. Models were classified into three: 1-Single and multiple variable regressions of lime mass and dimensional characteristics. 2-Single and multiple variable regressions of lime mass and projected areas. 3-Single regression of lime mass based on its actual volume and calculated volume assumed as ellipsoid and prolate spheroid shapes. All properties considered in the current study were found to be statistically significant (ρ lime based on minor diameter and first projected area are the most appropriate models in the first and the second classifications, respectively. In third classification, the best model was obtained on the basis of the prolate spheroid volume. It was finally concluded that the suitable grading system of lime mass is based on prolate spheroid volume.

  18. Plasticity, Swell-Shrink, and Microstructure of Phosphogypsum Admixed Lime Stabilized Expansive Soil

    Directory of Open Access Journals (Sweden)

    Jijo James

    2016-01-01

    Full Text Available The study involved utilization of an industrial waste, Phosphogypsum (PG, as an additive to lime stabilization of an expansive soil. Three lime dosages, namely, initial consumption of lime (ICL, optimum lime content (OLC, and less than ICL (LICL, were identified for the soil under study for stabilizing the soil. Along with lime, varying doses of PG were added to the soil for stabilization. The effect of stabilization was studied by performing index tests, namely, liquid limit, plastic limit, shrinkage limit, and free swell test, on pulverized remains of failed unconfined compression test specimens. The samples were also subjected to a microstructural study by means of scanning electron microscope. Addition of PG to lime resulted in improvement in the plasticity and swell-shrink characteristics. The microstructural study revealed the formation of a dense compact mass of stabilized soil.

  19. Common bean cultivars response to lime surface application under no tillage systemResposta de cultivares de feijoeiro comum à calagem superficial em semeadura direta

    Directory of Open Access Journals (Sweden)

    Carlos Alexandre Costa Crusciol

    2012-08-01

    Full Text Available Soil acidity in no tillage system, if not in high situations, can be neutralized by lime surface application, improving mineral nutrition and crop yield. Aiming to evaluate the agronomic performance of common bean cultivars, to surface lime application, in no tillage system, an experiment was conducted in Oxisol, Botucatu Municipal District, São Paulo State, Brazil. The experimental design was a complete randomized block in split plot with four replications, where the plots were formed by common bean cultivars (Carioca, IAC Carioca Eté, Pérola, IAPAR 81 e Campeão 2 and subplots consisted of surface application of dolomitic limestone (zero, 1.8 t ha-1, 3.6 t ha-1 and 5.4 t ha-1. The surface lime application on the soil occurred in October 2002 and subsequently the sequence millet (spring – beans (summer – oat (autumn-winter were planted under rainfed conditions. Bean cultivars sowing were done on December 17, 2003. It can be concluded that there is influence of cultivars and limestone surface application under no tillage, where IAPAR 81 showed better grain yield with the increase of lime rates, obtaining values of 2,025 kg ha-1 without the lime application to 2,655 kg ha-1 with 5.4 t ha-1 lime rate, obtaining 31% yield increase. A acidez do solo no sistema de semeadura direta, caso não se encontre em situações elevadas, pode ser resolvida com aplicação superficial de calcário, melhorando a nutrição mineral e a produtividade das culturas. Com o objetivo de avaliar o desempenho agronômico de cultivares de feijoeiro, em razão da aplicação superficial de calcário, em semeadura direta, foi realizado um experimento num Latossolo Vermelho distrófico, em Botucatu (SP. O delineamento experimental foi o de blocos casualizados, em esquema de parcelas subdivididas com quatro repetições, onde as parcelas foram formadas por cultivares de feijão comum (Carioca, IAC Carioca Eté, Pérola, IAPAR 81 e Campeão 2 e as subparcelas constitu

  20. Influencing factors of compressive strength of solidified inshore saline soil using SH lime-ash

    Institute of Scientific and Technical Information of China (English)

    覃银辉; 刘付华; 周琦

    2008-01-01

    Through unconfined compressive strength test,influencing factors on compressive strength of solidified inshore saline soil with SH lime-ash,ratio of lime-ash(1-K),quantity of lime-ash,age,degree of compression and salt content were studied.The results show that because inshore saline soil has special engineering characteristic,more influencing factors must be considered compared with ordinary soil for the perfect effect of solidifying.

  1. Effect of Liming on Cadmium Forms and Its Toxicity in Red Soils

    Institute of Scientific and Technical Information of China (English)

    A.M.FARAH; XIEZHENGMIAO; 等

    1996-01-01

    The effect of liming 4 soils developed from Quaternary red clay and red sandstone on the cadmium forms and its toxicity were investigated.Liming the acid red soils could greatly reduce Cd toxicity to plants because the soluble Cd and organic Cd in the soils decreased significantly while Cd bound to minerals/oxides and residual Cd increased markedly with increasing lime rates(pH).

  2. COMPARATIVE EXTRACTION OF PECTIC AND POLYPHENOLS FROM MEXICAN LIME POMACE AND BAGASSE

    OpenAIRE

    2013-01-01

    Mexican lime bagasse and pomace are rich in pectin and they also represent an important source of value-added compounds such as polyphenols. Two different options for the combined recovery of pectin and phenolic compounds from Mexican lime bagasse and pomace, two byproducts of industrial lime processing, were developed. Conventional and microwave-assisted extraction methods were used. All pectic extracts presented a degree of esterification in the range of 70%. Pomace extracts had the higher ...

  3. Lime-based repair mortars with water-repellent admixtures: laboratory durability assessment

    OpenAIRE

    Nunes, C.; Slížková, Z. (Zuzana)

    2015-01-01

    Conservation of architectural structures using lime binders is currently an important research topic aiming compatibility, durability and sustainability. In this study, lime (L) and lime-metakaolin (LM) mortars were prepared with the addition of water-repellent admixtures: linseed oil, stand oil and a silane based water-repellent. Experimental results demonstrate that oil imparts higher hydrophobicity to both L and LM mixtures. Durability was assessed through freeze-thaw and NaCl crystal...

  4. Hydration of highly charged ions.

    Science.gov (United States)

    Hofer, Thomas S; Weiss, Alexander K H; Randolf, Bernhard R; Rode, Bernd M

    2011-08-01

    Based on a series of ab initio quantum mechanical charge field molecular dynamics (QMCF MD) simulations, the broad spectrum of structural and dynamical properties of hydrates of trivalent and tetravalent ions is presented, ranging from extreme inertness to immediate hydrolysis. Main group and transition metal ions representative for different parts of the periodic system are treated, as are 2 threefold negatively charged anions. The results show that simple predictions of the properties of the hydrates appear impossible and that an accurate quantum mechanical simulation in cooperation with sophisticated experimental investigations seems the only way to obtain conclusive results.

  5. Great Market Potential of Hydrazine Hydrate

    Institute of Scientific and Technical Information of China (English)

    Shi Yuying

    2007-01-01

    @@ Stable consumption growth worldwide Hydrazine hydrate is an organic chemical raw material with extensive applications. The world's capacity to produce hydrazine hydrate has reached more than 200 thousand t/atoday (based on 100% hydrazine content).

  6. Methods to determine hydration states of minerals and cement hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Baquerizo, Luis G., E-mail: luis.baquerizoibarra@holcim.com [Innovation, Holcim Technology Ltd., CH-5113 Holderbank (Switzerland); Matschei, Thomas [Innovation, Holcim Technology Ltd., CH-5113 Holderbank (Switzerland); Scrivener, Karen L. [Laboratory of Construction Materials, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Saeidpour, Mahsa; Thorell, Alva; Wadsö, Lars [Building Materials, Lund University, Box 124, 221 000 Lund (Sweden)

    2014-11-15

    This paper describes a novel approach to the quantitative investigation of the impact of varying relative humidity (RH) and temperature on the structure and thermodynamic properties of salts and crystalline cement hydrates in different hydration states (i.e. varying molar water contents). The multi-method approach developed here is capable of deriving physico-chemical boundary conditions and the thermodynamic properties of hydrated phases, many of which are currently missing from or insufficiently reported in the literature. As an example the approach was applied to monosulfoaluminate, a phase typically found in hydrated cement pastes. New data on the dehydration and rehydration of monosulfoaluminate are presented. Some of the methods used were validated with the system Na{sub 2}SO{sub 4}–H{sub 2}O and new data related to the absorption of water by anhydrous sodium sulfate are presented. The methodology and data reported here should permit better modeling of the volume stability of cementitious systems exposed to various different climatic conditions.

  7. Novel understanding of calcium silicate hydrate from dilute hydration

    KAUST Repository

    Zhang, Lina

    2017-05-13

    The perspective of calcium silicate hydrate (C-S-H) is still confronting various debates due to its intrinsic complicated structure and properties after decades of studies. In this study, hydration at dilute suspension of w/s equaling to 10 was conducted for tricalcium silicate (C3S) to interpret long-term hydration process and investigate the formation, structure and properties of C-S-H. Based on results from XRD, IR, SEM, NMR and so forth, loose and dense clusters of C-S-H with analogous C/S ratio were obtained along with the corresponding chemical formulae proposed as Ca5Si4O13∙6.2H2O. Crystalline structure inside C-S-H was observed by TEM, which was allocated at the foil-like proportion as well as the edge of wrinkles of the product. The long-term hydration process of C3S in dilute suspension could be sketchily described as migration of calcium hydroxide and in-situ growth of C-S-H with equilibrium silicon in aqueous solution relatively constant and calcium varied.

  8. Multistage dolomitization in the Acungui Group metacarbonate rocks, Proterozoic of Parana state, Brazil; Dolomitizacao multifasica em reochas metacarbonaticas do Grupo Acungui, Proterozoico do estado do Parana, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Pinto-Coelho, Cristina Valle; Reis Neto, Jose Manoel dos [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Dept. de Geologia], e-mail: cristinavpc@ufpr.br, e-mail: jmreis@ufpr.br, e-mail: salla82@gmail.com; Eeva, Salla Talvikki [PETROBRAS (Brazil). E e P. Gerencia de Estratigrafia e Sedimentologia

    2007-11-15

    The carbonate rocks of Rio Bonito Quarry, at the state of Parana, are represented by metamarls, mylonized rocks, calcite and dolomite marbles and dolomite breccias, which were formed in several burial stages. The first dolomitization process which affected the marbles had its origin in a burial environment. The process occurred during Mesoproterozoic, where a precedent calcitic rock had its matrix replaced by fine to medium sized dolomite crystals with cloudy aspect, and where styolites and fractures formed the principal conduits for the circulation of Mg-rich solutions. The dolomite breccia were formed during the Brazilian Cycle (Neoproterozoic), in conditions of hydraulic fracturing, originated by devolatilization which occurred during the metamorphism of green schist facies. The second dolomitization process, caused the formation of Fe-rich microcrystalline dolomite (Dp1), originated through a fluid at chemical disequilibrium with the fluid responsible for the former dolomitization. In the Paleozoic occurred a new phase of dolomitization, developing the Dp2-type dolomite, as the consequence of reactivation of deep crustal faults or igneous intrusions (dykes of microgabbro). This dolomite is constituted by saddle dolomite, with nonplanar and coarse crystals, strong undulate extinction, which fills fractures in breccias as well as in dolomitic marbles. Superficial processes at the Paleogene, related to the topographic evolution, promoted the percolation of low-temperature fluids, occasioning the process of dedolomitization via dissolution and posterior filling of cavities. The process of dedolomitization occurred in dolomitic breccia with precipitation of late calcite, which filled the cavities, associated to dolomite of generation Dp2. Quartz completes the final phase of the void-filling process.(author)

  9. Origin of dolomitic rocks in the lower Permian Fengcheng formation, Junggar Basin, China: evidence from petrology and geochemistry

    Science.gov (United States)

    Zhu, Shifa; Qin, Yi; Liu, Xin; Wei, Chengjie; Zhu, Xiaomin; Zhang, Wei

    2016-09-01

    Although dolomitization of calcite minerals and carbonatization of volcanic rocks have been studied widely, the extensive dolomitic rocks that originated from altered volcanic and volcaniclastic rocks have not been reported. The dolomitic rocks of the Fengcheng Formation in the Junggar Basin of China appear to be formed under unusual geologic conditions. The petrological and geochemical characteristics indicate that the dolomitizing host rock is devitrified volcanic tuff. After low-temperature alteration and calcitization, these tuffaceous rocks are replaced by Mg-rich brine to form massive dolomitic tuffs. We propose that the briny (with -2 ‰ ~ 6 ‰ of δ13CPDB and -5 ‰ ~ 4 ‰ of δ18OPDB) and Mg-rich marine formation water (with 0.7060 ~ 0.7087 of 87Sr/86Sr ratio), the thick and intermediate-mafic volcanic ashes, and the tectonically compressional movement may have favored the formation of the unusual dolomitic rocks. We conclude that the proposed origin of the dolomitic rocks can be extrapolated to other similar terranes with volcaniclastic rocks, seabed tuffaceous sediment, and fracture filling of sill.

  10. Numerical simulation of thermal process and energy saving of lime furnace

    Institute of Scientific and Technical Information of China (English)

    YI Zheng-ming; ZHOU Jie-min; CHEN Hong-rong

    2005-01-01

    Based on the principle of thermal balance and material balance of lime furnace, the reaction and heat transfer process mathematical-physical model and the on-line monitoring model of the decomposition rate of limestone were set up. With this model, numerical simulation is used to analyze the effects of operational parameters on the process of lime calcining and to optimize it. By using visual basic program to communicate and program, the centralized management and automatic control of the lime furnace are realized. The software is put into practical production, which makes the lime furnace operate steadily and efficiently, and causes the increase in output and decrease in energy consumption.

  11. Long-term field-scale experiment on using lime filters in an agricultural catchment.

    Science.gov (United States)

    Kirkkala, Teija; Ventelä, Anne-Mari; Tarvainen, Marjo

    2012-01-01

    The River Yläneenjoki catchment in southwest Finland is an area with a high agricultural nutrient load. We report here on the nutrient removal performance of three on-site lime-sand filters (F1, F2, and F3), established within or on the edge of the buffer zones. The filters contain burnt lime (CaO) or spent lime [CaO, Ca(OH), and CaCO]. Easily soluble lime results in a high pH level (>11) and leads to an efficient precipitation of soluble phosphorus (P) from the runoff. Water samples were taken from the inflow and outflow of each site in different hydrological situations. The length of the monitoring period was 4 yr for F1, 6 yr for F2, and 1.5 yr for F3. F1 and F2 significantly reduced the suspended solids (SS), total P (PTOT), and dissolved reactive P (DRP) in the treated water. The proportional reduction (%) varied but was usually clearly positive. Filter F3 was divided into two equal parts, one containing burnt lime and the other spent lime. Both filter parts removed PTOT and SS efficiently from the water; the burnt-lime part also removed DRP. The mixed-lime part removed DRP for a year, but then the efficiency decreased. The effect of filters on nitrogen compounds varied. We conclude that sand filters incorporating lime can be used together with buffer zones to reduce both P and SS load to watercourses.

  12. Lime application methods, water and bottom soil acidity in fresh water fish ponds

    Directory of Open Access Journals (Sweden)

    Queiroz Julio Ferraz de

    2004-01-01

    Full Text Available Although some methods for determining lime requirement of pond soils are available and commonly used, there is still no consensus on whether it is more effective to apply liming materials to the bottoms of empty ponds or to wait and apply them over the water surface after ponds are filled. There is also little information on how deep lime reacts in pond sediment over time, and whether the depth of reaction is different when liming materials are applied to the water or to the soil. Therefore, three techniques for treating fish ponds with agricultural limestone were evaluated in ponds with clayey soils at a commercial fish farm. Amounts of agricultural limestone equal to the lime requirement of bottom soils were applied to each of three ponds by: direct application over the pond water surface; spread uniformly over the bottom of the empty pond; spread uniformly over the bottom of the empty pond followed by tilling of the bottom. Effectiveness of agricultural limestone applications did not differ among treatment methods. Agricultural limestone also reacted quickly to increase total alkalinity and total hardness of pond water to acceptable concentrations within 2 weeks after application. The reaction of lime to increase soil pH was essentially complete after one to two months, and lime had no effect below a soil depth of 8 cm. Tilling of pond bottoms to incorporate liming materials is unnecessary, and tilling consumes time and is an expensive practice; filled ponds can be limed effectively.

  13. Molecular Dynamics Modeling of Hydrated Calcium-Silicate-Hydrate (CSH) Cement Molecular Structure

    Science.gov (United States)

    2014-08-30

    properties of key hydrated cement constituent calcium-silicate-hydrate (CSH) at the molecular, nanometer scale level. Due to complexity, still unknown...public release; distribution is unlimited. Molecular Dynamics Modeling of Hydrated Calcium-Silicate- Hydrate (CSH) Cement Molecular Structure The views... Cement Molecular Structure Report Title Multi-scale modeling of complex material systems requires starting from fundamental building blocks to

  14. Hydration and Thermal Expansion in Anatase Nanoparticles.

    Science.gov (United States)

    Zhu, He; Li, Qiang; Ren, Yang; Fan, Longlong; Chen, Jun; Deng, Jinxia; Xing, Xianran

    2016-08-01

    A tunable thermal expansion is reported in nanosized anatase by taking advantage of surface hydration. The coefficient of thermal expansion of 4 nm TiO2 along a-axis is negative with a hydrated surface and is positive without a hydrated surface. High-energy synchrotron X-ray pair distribution function analysis combined with ab initio calculations on the specific hydrated surface are carried out to reveal the local structure distortion that is responsible for the unusual negative thermal expansion.

  15. Hydration and Thermal Expansion in Anatase Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, He [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 China; Li, Qiang [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 China; Ren, Yang [Argonne National Laboratory, X-Ray Science Division, Argonne IL 60439 USA; Fan, Longlong [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 China; Chen, Jun [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 China; Deng, Jinxia [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 China; Xing, Xianran [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 China

    2016-06-06

    A tunable thermal expansion is reported in nanosized anatase by taking advantage of surface hydration. The coefficient of thermal expansion of 4 nm TiO2 along a-axis is negative with a hydrated surface and is positive without a hydrated surface. High-energy synchrotron X-ray pair distribution function analysis combined with ab initio calculations on the specific hydrated surface are carried out to reveal the local structure distortion that is responsible for the unusual negative thermal expansion.

  16. Use of bottom ash from thermal power plant and lime as filler in bituminous mixtures

    Directory of Open Access Journals (Sweden)

    López-López, E.

    2015-06-01

    Full Text Available This study focuses on the characterization of bottom ash (PCC-BA and determining the mechanical characteristics of hot mix asphalt (HMA using PCC-BA and hydrated lime (HL as filler. Physical and chemical characterization of the bottom ash was carried out to evaluate its eventual reutilization as filler substitute. The materials tested in this study were made using 0%, 25%, 50%, 70% and 100% of PCC-BA combined with HL. HMA mixes were evaluated in terms of their engineering properties, namely: air voids in the mixes, water sensitivity, stiffness modulus, performance in wheel tracking test and fatigue resistance. The results obtained indicate that HMA mixes with a filler blend of 70% PCC-BA and 30% HL fulfil European standards and are suitable for light traffic or small infrastructures.Este estudio se centra en la caracterización de las cenizas de fondo (PCC-BA y la determinación de las características mecánicas de mezclas bituminosas en caliente (HMA, utilizando cenizas de fondo y la cal hidratada (HL como filler. Se realizó la caracterización física y química de las cenizas de fondo para evaluar su empleo como sustituto de filler. Las mezclas ensayadas en este estudio se realizaron utilizando 0%, 25%, 50%, 70% y 100% de cenizas de fondo combinadas con cal hidratada. Se evaluaron propiedades ingenieriles de las mezclas bituminosas, tales como los huecos de aire en las mezclas, la sensibilidad al agua, el módulo de rigidez, el ensayo de pista y la resistencia a la fatiga. Los resultados obtenidos indican que las mezclas bituminosas fabricadas con una combinación de filler del 70% de cenizas de fondo y el 30% cal hidratada, cumplen con las normas europeas y son adecuados para su aplicación con tráficos ligeros o en pequeñas infraestructuras.

  17. Lime Kiln Modeling. CFD and One-dimensional simulations

    Energy Technology Data Exchange (ETDEWEB)

    Svedin, Kristoffer; Ivarsson, Christofer; Lundborg, Rickard

    2009-03-15

    The incentives for burning alternative fuels in lime kilns are growing. An increasing demand on thorough investigations of alternative fuel impact on lime kiln performance have been recognized, and the purpose of this project has been to develop a lime kiln CFD model with the possibility to fire fuel oil and lignin. The second part of the project consists of three technical studies. Simulated data from a one-dimensional steady state program has been used to support theories on the impact of biofuels and lime mud dryness. The CFD simulations was carried out in the commercial code FLUENT. Due to difficulties with the convergence of the model the calcination reaction is not included. The model shows essential differences between the two fuels. Lignin gives a different flame shape and a longer flame length compared to fuel oil. Mainly this depends on how the fuel is fed into the combustion chamber and how much combustion air that is added as primary and secondary air. In the case of lignin combustion the required amount of air is more than in the fuel oil case. This generates more combustion gas and a different flow pattern is created. Based on the values from turbulent reaction rate for the different fuels an estimated flame length can be obtained. For fuel oil the combustion is very intense with a sharp peak in the beginning and a rapid decrease. For lignin the combustion starts not as intense as for the fuel oil case and has a smoother shape. The flame length appears to be approximately 2-3 meter longer for lignin than for fuel oil based on turbulent reaction rate in the computational simulations. The first technical study showed that there are many benefits of increasing dry solids content in the lime mud going into a kiln such as increased energy efficiency, reduced TRS, and reduced sodium in the kiln. However, data from operating kilns indicates that these benefits can be offset by increasing exit gas temperature that can limit kiln production capacity. Simulated

  18. Lime Kiln Modeling. CFD and One-dimensional simulations

    Energy Technology Data Exchange (ETDEWEB)

    Svedin, Kristoffer; Ivarsson, Christofer; Lundborg, Rickard

    2009-03-15

    The incentives for burning alternative fuels in lime kilns are growing. An increasing demand on thorough investigations of alternative fuel impact on lime kiln performance have been recognized, and the purpose of this project has been to develop a lime kiln CFD model with the possibility to fire fuel oil and lignin. The second part of the project consists of three technical studies. Simulated data from a one-dimensional steady state program has been used to support theories on the impact of biofuels and lime mud dryness. The CFD simulations was carried out in the commercial code FLUENT. Due to difficulties with the convergence of the model the calcination reaction is not included. The model shows essential differences between the two fuels. Lignin gives a different flame shape and a longer flame length compared to fuel oil. Mainly this depends on how the fuel is fed into the combustion chamber and how much combustion air that is added as primary and secondary air. In the case of lignin combustion the required amount of air is more than in the fuel oil case. This generates more combustion gas and a different flow pattern is created. Based on the values from turbulent reaction rate for the different fuels an estimated flame length can be obtained. For fuel oil the combustion is very intense with a sharp peak in the beginning and a rapid decrease. For lignin the combustion starts not as intense as for the fuel oil case and has a smoother shape. The flame length appears to be approximately 2-3 meter longer for lignin than for fuel oil based on turbulent reaction rate in the computational simulations. The first technical study showed that there are many benefits of increasing dry solids content in the lime mud going into a kiln such as increased energy efficiency, reduced TRS, and reduced sodium in the kiln. However, data from operating kilns indicates that these benefits can be offset by increasing exit gas temperature that can limit kiln production capacity. Simulated

  19. Terahertz sensing of corneal hydration.

    Science.gov (United States)

    Singh, Rahul S; Tewari, Priyamvada; Bourges, Jean Louis; Hubschman, Jean Pierre; Bennett, David B; Taylor, Zachary D; Lee, H; Brown, Elliott R; Grundfest, Warren S; Culjat, Martin O

    2010-01-01

    An indicator of ocular health is the hydrodyanmics of the cornea. Many corneal disorders deteriorate sight as they upset the normal hydrodynamics of the cornea. The mechanisms include the loss of endothelial pump function of corneal dystophies, swelling and immune response of corneal graft rejection, and inflammation and edema, which accompany trauma, burn, and irritation events. Due to high sensitivity to changes of water content in materials, a reflective terahertz (300 GHz and 3 THz) imaging system could be an ideal tool to measure the hydration level of the cornea. This paper presents the application of THz technology to visualize the hydration content across ex vivo porcine corneas. The corneas, with a thickness variation from 470 - 940 µm, were successfully imaged using a reflective pulsed THz imaging system, with a maximum SNR of 50 dB. To our knowledge, no prior studies have reported on the use of THz in measuring hydration in corneal tissues or other ocular tissues. These preliminary findings indicate that THz can be used to accurately sense hydration levels in the cornea using a pulsed, reflective THz imaging system.

  20. Physical properties of gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Kliner, J.T.R.; Grozic, J.L.H. [Calgary Univ., AB (Canada)

    2003-07-01

    Gas hydrates are naturally occurring, solid crystalline compounds (clathrates) that encapsulate gas molecules inside the lattices of hydrogen bonded water molecules within a specific temperature-pressure stability zone. Estimates of the total quantity of available methane gas in natural occurring hydrates are based on twice the energy content of known conventional fossil fuels reservoirs. Accurate and reliable in-situ quantification techniques are essential in determining the economic viability of this potential energy yield, which is dependent upon several factors such as sensitivity of the temperature-pressure stability zone, sediment type, porosity, permeability, concentration/abundance of free gas, spatial distribution in pore spaces, specific cage occupancy, and the influence of inhibitors. Various techniques like acoustic P and S waves, time domain reflectometry, and electrical resistance have been used to analyze the quantity and spatial distribution of the gas hydrate samples. These techniques were reviewed and the results obtained in the course of gas hydrate research were presented. 34 refs., 8 figs.

  1. Hydration kinetics of transgenic soybeans

    Directory of Open Access Journals (Sweden)

    Aline Francielle Fracasso

    2015-01-01

    Full Text Available The kinetic and experimental analyses of the hydration process of transgenic soybeans (BRS 225 RR are provided. The importance of the hydration process consists of the grain texture modifications which favor grinding and extraction of soybeans. The soaking isotherms were obtained for four different temperatures. Results showed that temperature affected transgenic soybeans´ hydration rate and time. Moisture content d.b. of the soybeans increased from 0.12 ± 0.01 kg kg-1 to 1.45 ± 0.19 kg kg-1 during 270 min. of process. Two models were used to fit the kinetic curves: an empirical model developed by Peleg (1988 and a phenomenological one, proposed by Omoto et al. (2009. The two models adequately represented the hydration kinetics. Peleg model was applied to the experimental data and the corresponding parameters were obtained and correlated to temperature. The model by Omoto et al. (2009 showed a better statistical fitting. Although Ks was affected by temperature (Ks = 0.38079 exp (-2289.3 T-1, the equilibrium concentration remained practically unchanged.

  2. Dolomitization in Late Jurassic-Early Cretaceous Platform Carbonates (Berdiga Formation), Ayralaksa Yayla (Trabzon), NE Turkey

    Science.gov (United States)

    Yıldız, Merve; Ziya Kırmacı, Mehmet; Kandemir, Raif

    2017-04-01

    ABSTRACT Pontides constitute an E-W trending orogenic mountain belt that extends about 1100 km along the northern side of Turkey from the immediate east of Istanbul to the Georgian border at the east. Tectono-stratigraphically, the Pontides are divided into three different parts: Eastern, Central, and Western Pontides. The Eastern Pontides, including the studied area, comprise an area of 500 km in length and 100 km in width, extending along the southeast coast of the Black Sea from the Kizilirmak and Yesilirmak Rivers in the vicinity of Samsun to the Little Caucasus. This area is bordered by the Eastern Black Sea basin to the north and the Ankara-Erzincan Neotethyan suture zone to the south. The Late Jurassic-Early Cretaceous platform carbonates are widely exposed in E-W direction in the Eastern Pontides (NE Turkey). The Platform carbonates shows varying lithofacies changing from supratidal to platform margin reef laterally and vertically, and was buried until the end of Late Cretaceous. The studied Ayralaksa Yayla (Trabzon, NE Turkey) area comprises one of the best typical exposures of formation in northern zone of Eastern Pontides. In this area, the lower parts of the formation are pervasively dolomitized by fabric-destructive and fabric-preserving replacement dolomite which are Ca-rich and nonstoichiometric (Ca56-66Mg34-44). Replacement dolomites (Rd) are represented by D18O values of -19.0 to -4.2 (VPDB), D13C values of 4.4 to 2.1 \\permil (VPDB) and 87Sr/86Sr ratios of 0.70889 to 0.70636. Petrographic and geochemical data indicate that Rd dolomites are formed prior to compaction at shallow-moderate burial depths from Late Jurassic-Early Cretaceous seawater and/or partly modified seawater as a result of water/rock interaction and they were recrystallized at elevated temperatures during subsequent burial. In the subsequent diagenetic process during the Late Cretaceous when the region became a magmatic arc, as a result of interaction with Early Jurassic volcanic

  3. Clumped isotope thermometry of calcite and dolomite in a contact metamorphic environment

    Science.gov (United States)

    Lloyd, Max K.; Eiler, John M.; Nabelek, Peter I.

    2017-01-01

    Clumped isotope compositions of slowly-cooled calcite and dolomite marbles record apparent equilibrium temperatures of roughly 150-200 °C and 300-350 °C, respectively. Because clumped isotope compositions are sensitive to the details of T-t path within these intervals, measurements of the Δ47 values of coexisting calcite and dolomite can place new constraints on thermal history of low-grade metamorphic rocks over a large portion of the upper crust (from ∼5 to ∼15 km depth). We studied the clumped isotope geochemistry of coexisting calcite and dolomite in marbles from the Notch Peak contact metamorphic aureole, Utah. Here, flat-lying limestones were intruded by a pluton, producing a regular, zoned metamorphic aureole. Calcite Δ47 temperatures are uniform, 156 ± 12 °C (2σ s.e.), across rocks varying from high-grade marbles that exceeded 500 °C to nominally unmetamorphosed limestones >5 km from the intrusion. This result appears to require that the temperature far from the pluton was close to this value; an ambient temperature just 20 °C lower would not have permitted substantial re-equilibration, and should have preserved depositional or early diagenetic Δ47 values several km from the pluton. Combining this result with depth constraints from overlying strata suggests the country rock here had an average regional geotherm of 22.3-27.4 °C/km from the late Jurassic Period until at least the middle Paleogene Period. Dolomite Δ47 in all samples above the talc + tremolite-in isograd record apparent equilibrium temperatures of 328-12+13 °C (1σ s.e.), consistent with the apparent equilibrium blocking temperature we expect for cooling from peak metamorphic conditions. At greater distances, dolomite Δ47 records temperatures of peak (anchi)metamorphism or pre-metamorphic diagenetic conditions. The interface between these domains is the location of the 330 °C isotherm associated with intrusion. Multiple-phase clumped isotope measurements are complemented by

  4. Reconstruction of the pre-compactional thickness of the Zechstein Main Dolomite in northwest Poland

    Directory of Open Access Journals (Sweden)

    Semyrka Grażyna

    2015-12-01

    Full Text Available Our reconstruction of the pre-compactional thickness of the Main Dolomite strata from the so-called Grotów Peninsula (northwest Poland was based on macroscopic observations of drill cores from three wells: Mokrzec-1, Sieraków-4 and Międzychód-5. These wells are located in various palaeogeographical zones of the Main Dolomite and cored rocks represent a range of microfacies. The amount of compactional reduction in thickness of the Main Dolomite was estimated by summing the total heights (Wst of all stylolites encountered in logs of these wells. For calculations, a generalised model of a drill core was developed, which embraced all types of stylolite seams present in the Main Dolomite succession studied. Also the method of stylolite dimensioning was demonstrated. The number of stylolites in the drill cores studied varied from 511 in the Sieraków-4 well to 1,534 in the Międzychód-5 well. In all cores studied low-amplitude macrostylolites predominated, but the reduction of thickness was controlled mostly by the low- and medium-amplitude macrostylolites. The largest number of stylolites was found in the grainstone/packstone microfacies. The turnout of stylolites depends of microfacies. The highest density of stylolites was documented in mudstones/wackestones (24 stylolites per metre of rock thickness and the lowest in boundstones (14 stylolites per metre of rock thickness. The low-amplitude stylolites appear most frequently in the mudstone/wackestone microfacies (15 stylolites per metre of rock thickness; in grainstones/packstones, rudstones/floatstones and boundstones middle-amplitude stylolites are rare (3 stylolites per metre of rock thickness. The degree of compaction of the Main Dolomite succession studied varied from 6 to 10%; hence, its calculated initial thickness also varied in the wells studied: from 41.3 m in the Sieraków-4 well to 56.9 m in the Mokrzec-1 well and to 97.1 m in the Międzychód-5 well. The volumes of reservoir

  5. The effectiveness of surface liming in ameliorating the phytotoxic effects of soil contaminated by copper acid leach pad solution in an arid ecosystem

    Science.gov (United States)

    Golos, Peter

    2016-04-01

    Revegetation of sites following soil contamination can be challenging especially in identifying the most effective method for ameliorating phytotoxic effects in arid ecosystems. This study at a copper mine in the Great Sandy Desert of Western Australia investigated vegetation restoration of a site contaminated by acid (H2SO4) leach pad solution. Elevated soil copper at low soil pH is phytotoxic to plant roots inhibiting root elongation. In arid ecosystems where rapid root growth is crucial for seedling survival post germination physical or chemical barriers to root growth need to be identified and ameliorated. Initial attempt at rehabilitation of contaminated site with hydrated lime (CaOH2) at 2 tonnes/ha followed by ripping to 30 cm depth then seeding was ineffective as successful seedling emergence was followed by over 90% seedling mortality which was 10-fold greater than seedling mortality in an uncontaminated reference site. High mortality was attributed to seedling roots being impededed as soil water was more than 3-fold greater at 5 to 40 cm depth in contaminated site than reference site. In response to high seedling mortality after emergence test pits were dug to 1 m deep to collect soil samples at 10 cm intervals for phytotoxicity testing and to measure soil pH-CaCl2, copper (DPTA ion extraction), electrical conductivity and gravimetric water content in three replicate pits at three replicate sites. Also, soil impedance was measured down the soil profile at 5 cm intervals at six replicate points/pit. For phytotoxicity testing soil samples were placed into three replicate plastic pots/sample and seeded with 10 seeds of Avena sativa and watered daily. Seedlings were harvested after at least two weeks after seedling emergence and rooting depth in pots measured. There was no difference in seedling emergence and survival of seedlings between contaminated and uncontaminated soil samples however mean seedling root growth was significantly lower in soil samples

  6. CHEMICAL ANALYSIS OF DENSE-GAS EXTRACTS FROM LIME FLOWERS

    Directory of Open Access Journals (Sweden)

    Demyanenko DV

    2015-04-01

    Full Text Available The purpose of this work was to make qualitative and quantitative analysis of phenolic biologically active substances (BAS in the extracts produced from lime flowers with condensed gases, using method of high-performance liquid chromatography (HPLC. Materials and methods: materials for this study were the extracts obtained by consequent processing of the herbal drug and marcs thereof with various condensed gases: difluorochloromethane (Freon R22, difluoromethane (Freon R32, azeotropic mixture of difluoromethane with pentafluoroethane (Freon 410A and freon-ammonium mixture. Extracts obtained with the latter were subjected to further fractionation by liquidliquid separation into hexane, chloroform, ethyl acetate and aqueous-alcohol phases. Besides, the supercritical СО2 extract, obtained from the herbal drug under rather strong conditions (at temperature 60°С and pressure 400 bar, was studied in our previous research. Presence of phenolic BAS and their quantity in the researched samples were determined by method of HPLC with UVspectrometric detection. Results and discussion: It has been found that Freon R22 extracted trace amounts of rutin from lime flowers – its content was only 0.08% of the total extract weight. On the other hand, Freons R32 and R410А showed good selectivity to moderately polar BAS of lime flowers (derivatives of flavonoids and hydroxycinnamic acids: in particular, the extract obtained with freon R32 contained about 1.3% of the total phenolic substances, and it was the only one of the investigated condensed gases used by us which took the basic flavonoid of lime flowers tiliroside – its content was 0.42% of extract weight. Also Freons R32 and R410А were able to withdraw another compound dominating among phenolic substances in the yielded extracts. Its quantity was rather noticeable – up to 0.87% of extract weight. This substance was not identified by existing database, but its UV-spectrum was similar to those of

  7. Physical activity, hydration and health

    Directory of Open Access Journals (Sweden)

    Ascensión Marcos

    2014-06-01

    Full Text Available Since the beginning of mankind, man has sought ways to promote and preserve health as well as to prevent disease. Hydration, physical activity and exercise are key factors for enhancing human health. However, either a little dose of them or an excess can be harmful for health maintenance at any age. Water is an essential nutrient for human body and a major key to survival has been to prevent dehydration. However, there is still a general controversy regarding the necessary amount to drink water or other beverages to properly get an adequate level of hydration. In addition, up to now the tools used to measure hydration are controversial. To this end, there are several important groups of variables to take into account such as water balance, hydration biomarkers and total body water. A combination of methods will be the most preferred tool to find out any risk or situation of dehydration at any age range. On the other hand, physical activity and exercise are being demonstrated to promote health, avoiding or reducing health problems, vascular and inflammatory diseases and helping weight management. Therefore, physical activity is also being used as a pill within a therapy to promote health and reduce risk diseases, but as in the case of drugs, dose, intensity, frequency, duration and precautions have to be evaluated and taken into account in order to get the maximum effectiveness and success of a treatment. On the other hand, sedentariness is the opposite concept to physical activity that has been recently recognized as an important factor of lifestyle involved in the obesogenic environment and consequently in the risk of the non-communicable diseases. In view of the literature consulted and taking into account the expertise of the authors, in this review a Decalogue of global recommendations is included to achieve an adequate hydration and physical activity status to avoid overweight/obesity consequences.

  8. [The Analysis of Traditional Lime Mortars from Zhejiang Province, China].

    Science.gov (United States)

    Liu, Xiao-bin; Cui, Biao; Zhang, Bing-jian

    2016-01-01

    The components of ancient mortars have always been an important research field in historic building conservation. It has been well known that using traditional mortars in conservation projects have many advantages, such as compatibility and stability. So, developing new binding materials based on traditional mortar has become an international study hotspot. With China's economic development, the protection of ancient buildings also began to put on the agenda, but the understanding on Chinese traditional mortar is limited, and rare literatures are reported. In the present work, the authors investigate seven ancient city wall sites in Zhejiang Province in situ, and subsequently laboratory analysis were carried out on collected mortar samples. The characterizations of mortar samples were made by multi-density gauge, XRD, FTIR, TG-DSC and wet chemical analysis. The experimental results showed that: the main component of masonry mortars is calcium carbonate, the content between 75% - 90%, and they should be made from relatively pure lime mortar. The raw materials of mortar samples were mainly calcareous quick lime, and sample from Taizhou city also contained magnesium quick lime. There are four city walls were built by sticky-rice mortars. It suggests that the technology of adding the sticky rice soup into mortar was universal in the Ming Dynasties. These mortars have lower density between 1.2 and 1.9 g x cm(-3); this outcome should be the result of long-term natural erosion. We have also analyzed other chemical and physical characteristics of these masonry mortars. The results can afford the basic data for the future repairmen programs, development of new protective materials, and comparative study of mortars.

  9. Lime and fertilizer recommendation system for coconut trees

    Directory of Open Access Journals (Sweden)

    Gustavo Nogueira Guedes Pereira Rosa

    2011-02-01

    Full Text Available Fertilizer recommendation to most agricultural crops is based on response curves. Such curves are constructed from field experimental data, obtained for a particular condition and may not be reliable to be applied to other regions. The aim of this study was to develop a Lime and Fertilizer Recommendation System for Coconut Crop based on the nutritional balance. The System considers the expected productivity and plant nutrient use efficiency to estimate nutrient demand, and effective rooting layer, soil nutrient availability, as well as any other nutrient input to estimate the nutrient supply. Comparing the nutrient demand with the nutrient supply the System defines the nutrient balance. If the balance for a given nutrient is negative, lime and, or, fertilization is recommended. On the other hand, if the balance is positive, no lime or fertilizer is needed. For coconut trees, the fertilization regime is divided in three stages: fertilization at the planting spot, band fertilization and fertilization at the production phase. The data set for the development of the System for coconut trees was obtained from the literature. The recommendations generated by the System were compared to those derived from recommendation tables used for coconut crop in Brazil. The main differences between the two procedures were for the P rate applied in the planting hole, which was higher in the proposed System because the tables do not pay heed to the pit volume, whereas the N and K rates were lower. The crop demand for K is very high, and the rates recommended by the System are superior to the table recommendations for the formation and initial production stage. The fertilizer recommendations by the System are higher for the phase of coconut tree growth as compared to the production phase, because greater amount of biomass is produced in the first phase.

  10. Forest liming increases forest floor carbon and nitrogen stocks in a mixed hardwood forest.

    Science.gov (United States)

    Melvin, April M; Lichstein, Jeremy W; Goodale, Christine L

    2013-12-01

    In acid-impacted forests, decreased soil pH and calcium (Ca) availability have the potential to influence biotic and abiotic controls on carbon (C) and nitrogen (N) cycling. We investigated the effects of liming on above- and belowground C and N pools and fluxes 19 years after lime addition to the Woods Lake Watershed, Adirondack Park, New York, USA. Soil pH and exchangeable Ca remained elevated in the forest floor and upper mineral soil of limed areas. Forest floor C and N stocks were significantly larger in limed plots (68 vs. 31 Mg C/ha, and 3.0 vs. 1.5 Mg N/ha), resulting from a larger mass of Oa material. Liming reduced soil basal respiration rates by 17% and 43% in the Oe and Oa horizons, respectively. Net N mineralization was significantly lower in the limed soils for both forest floor horizons. Additional measurements of forest floor depth outside of our study plots, but within the treatment and control subcatchments also showed a deeper forest floor in limed areas; however, the mean depth of limed forest floor was 5 cm shallower than that observed in our study plots. Using a differential equation model of forest floor C dynamics, we found that liming effects on C fluxes measured within our study plots could explain the small observed increase in the Oe C stock but were not large enough to explain the increase in the Oa. Our catchment-wide assessment of forest floor depth, however, indicates that our plot analysis may be an overestimate of ecosystem-scale C and N stocks. Our results suggest that the mechanisms identified in our study, primarily liming-induced reduction in decomposition rates, may account for much of the observed increase in forest floor C. These findings emphasize the importance of understanding of the effects of liming in hardwood forests, and the long-term impacts of acid deposition on forest C and N uptake and retention.

  11. Improvement in hardness of soda-lime-silica glass

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Riya; De, Moumita; Roy, Sudakshina; Dey, Arjun; Biswas, Sampad K.; Middya, Tapas Ranjan; Mukhopadhyay, Anoop K. [CSIR-Central Glass and Ceramic Research Institute, Kolkata-700032, CSIR (India); Department of Physics, Jadavpur University, Kolkata-700032 (India); CSIR-Central Glass and Ceramic Research Institute, Kolkata-700032, CSIR (India)

    2012-06-05

    Hardness is a key design parameter for structural application of brittle solids like glass. Here we report for the first time the significant improvement of about 10% in Vicker's hardness of a soda-lime-silica glass with loading rate in the range of 0.1-10 N.s{sup -1}. Corroborative dark field optical and scanning electron microscopy provided clue to this improvement through evidence of variations in spatial density of shear deformation band formation as a function of loading rate.

  12. Photoacoustic thermal characterization of lime-partially stabilized zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Contreras, M.E.; Serrato, J.; Zarate, J.; Pacheco, C.; Villasenor, L. [Univ. Michoacana, Morelia Michoacan (Mexico)

    1997-01-01

    Photoacoustic and photothermal techniques are used to investigate the room-temperature thermophysical properties of 9.4 mol% lime-partially stabilized zirconia (C-PSZ) samples in the density range of 5.12 {times} 10{sup 3}--5.58 {times} 10{sup 3}kg/m{sup 3}. The open-photoacoustic-cell approach is used to measure thermal diffusivity, and the photothermal technique of continuous illumination of the sample in vacuum is used to measure the product of density and specific heat capacity. Thermal conductivity is shown to be the thermophysical parameter most sensitive to changes in porosity.

  13. Seismic reflections associated with submarine gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Andreassen, K.

    1995-12-31

    Gas hydrates are often suggested as a future energy resource. This doctoral thesis improves the understanding of the concentration and distribution of natural submarine gas hydrates. The presence of these hydrates are commonly inferred from strong bottom simulating reflection (BSR). To investigate the nature of BSR, this work uses seismic studies of hydrate-related BSRs at two different locations, one where gas hydrates are accepted to exist and interpreted to be very extensive (in the Beaufort Sea), the other with good velocity data and downhole logs available (offshore Oregon). To ascertain the presence of free gas under the BSR, prestack offset data must supplement near-vertical incidence seismic data. A tentative model for physical properties of sediments partially saturated with gas hydrate and free gas is presented. This model, together with drilling information and seismic data containing the BSR beneath the Oregon margin and the Beaufort Sea, made it possible to better understand when to apply the amplitude-versus-offset (AVO) method to constrain BSR gas hydrate and gas models. Distribution of natural gas hydrates offshore Norway and Svalbard is discussed and interpreted as reflections from the base of gas hydrate-bearing sediments, overlying sediments containing free gas. Gas hydrates inferred to exist at the Norwegian-Svalbard continental margin correlate well with Cenozoic depocenters, and the associated gas is assumed to be mainly biogenic. Parts of that margin have a high potential for natural gas hydrates of both biogenic and thermogenic origin. 235 refs., 86 figs., 4 tabs.

  14. Uranium immobilization by sulfate-reducing biofilms grown on hematite, dolomite, and calcite.

    Science.gov (United States)

    Marsili, Enrico; Beyenal, Haluk; Di Palma, Luca; Merli, Carlo; Dohnalkova, Alice; Amonette, James E; Lewandowski, Zbigniew

    2007-12-15

    Biofilms of sulfate-reducing bacteria Desulfovibrio desulfuricans G20 were used to reduce dissolved U(VI) and subsequently immobilize U(IV) in the presence of uranium-complexing carbonates. The biofilms were grown in three identically operated fixed bed reactors, filled with three types of minerals: one noncarbonate-bearing mineral (hematite) and two carbonate-bearing minerals (calcite and dolomite). The source of carbonates in the reactors filled with calcite and dolomite were the minerals, while in the reactor filled with hematite it was a 10 mM carbonate buffer, pH 7.2, which we added to the growth medium. Our five-month study demonstrated that the sulfate-reducing biofilms grown in all reactors were able to immobilize/reduce uranium efficiently, despite the presence of uranium-complexing carbonates.

  15. EPR, UV-Visible, and Near-Infrared Spectroscopic Characterization of Dolomite

    Directory of Open Access Journals (Sweden)

    S. Lakshmi Reddy

    2008-01-01

    Full Text Available Dolomite mineral samples having white and light green colors of Indian origin have been characterized by EPR, optical, and NIR spectroscopy. The optical spectrum exhibits a number of electronic bands due to presence of Fe(III ions in the mineral. From EPR studies, the parameters of g for Fe(III and g,A, and D for Mn(II are evaluated and the data confirm that the ions are in distorted octahedron. Optical absorption studies reveal that Fe(III is in distorted octahedron. The bands in NIR spectra are due to the overtones and combinations of water molecules. Thus EPR and optical absorption spectral studies have proven useful for the study of the solid state chemistry of dolomite.

  16. Promotion of Coconut Shell Gasification by Steam Reforming on Nickel-Dolomite

    Directory of Open Access Journals (Sweden)

    Pattaraporn Chaiprasert

    2009-01-01

    Full Text Available Biomass gasification by the use of metallic nickel as active metal on dolomite support has been chosen as catalyst because of its activity in biomass steam gasification and tar reduction. The purpose of this study is to study the effects of critical parameters on product gas compositions such as temperature, steam to carbon ratio (S/C and oxygen input. The results showed the increasing carbon conversion to gas from 44.13-78.43% whereas tar was decreased from 19.55-1.4% at temperature of 800°C and S/C 0.95. It is found that Nickel-dolomite is effective for tar reduction and for improving the quality of syngas derived from biomass which is a renewable energy source.

  17. Olivine, dolomite and ceramic filters in one vessel to produce clean gas from biomass.

    Science.gov (United States)

    Rapagnà, Sergio; Gallucci, Katia; Foscolo, Pier Ugo

    2017-07-27

    Heavy organic compounds produced during almond shells gasification in a steam and/or air atmosphere, usually called tar, are drastically reduced in the product gas by using simultaneously in one vessel a ceramic filter placed in the freeboard and a mixture of olivine and dolomite particles in the fluidized bed of the gasifier. The content of tar in the product gas during a reference gasification test with air, in presence of fresh olivine particles only, was 8600mg/Nm(3) of dry gas. By gasifying biomass with steam at the same temperature level of 820°C in a bed of olivine and dolomite (20% by weight), and in the presence of a catalytic ceramic filter inserted in the freeboard of the fluidized bed gasifier, the level of tar was brought down to 57mg/Nm(3) of dry producct gas, with a decrease of more than two orders of magnitude. Copyright © 2017. Published by Elsevier Ltd.

  18. Dissolution Kinetics of Magnesitic-Dolomite and Magnesite-Chrome Refractories in Secondary Steelmaking Slags

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhaoyou; WU Xuezhen; YE Fangbao

    2007-01-01

    Dissolution kinetics of magnesitic-dolomite and magnesite-chrome refractories in secondary steelmaking slags was studied by means of the rotating cylinder method under forced convection. Materials investigated include four magnesitic-dolomite samples (MgO content 40% to 93% ) and two magnesite-chrome samples ( co-clinkered and semi-rebonded ). Synthetic slags simulative of VOD and AOD slags with varying basicity (0. 6-2. 68) are used. The experiments are carried out in Ar atmosphere at different temperatures (1 600 ℃-1 750 ℃ ) and revolumicrostructure of specimens (before and after slag tests)are studied by optical microscopy, SEM and EPMA.Based on our experimental results the mechanism and kinetics of the dissolution process are discussed.

  19. Handbook of gas hydrate properties and occurrence

    Energy Technology Data Exchange (ETDEWEB)

    Kuustraa, V.A.; Hammershaimb, E.C.

    1983-12-01

    This handbook provides data on the resource potential of naturally occurring hydrates, the properties that are needed to evaluate their recovery, and their production potential. The first two chapters give data on the naturally occurring hydrate potential by reviewing published resource estimates and the known and inferred occurrences. The third and fourth chapters review the physical and thermodynamic properties of hydrates, respectively. The thermodynamic properties of hydrates that are discussed include dissociation energies and a simplified method to calculate them; phase diagrams for simple and multi-component gases; the thermal conductivity; and the kinetics of hydrate dissociation. The final chapter evaluates the net energy balance of recovering hydrates and shows that a substantial positive energy balance can theoretically be achieved. The Appendices of the Handbook summarize physical and thermodynamic properties of gases, liquids and solids that can be used in designing and evaluating recovery processes of hydrates. 158 references, 67 figures, 47 tables.

  20. Separation of water through gas hydrate formation

    DEFF Research Database (Denmark)

    Boch Andersen, Torben; Thomsen, Kaj

    2009-01-01

    Gas hydrate is normally recognized as a troublemaker in the oil and gas industry. However, gas hydrate has some interesting possibilities when used in connection with separation of water. Nordic Sugar has investigated the possibility of using gas hydrates for concentration of sugar juice. The goa...... volumes and the needs for high pressure. The process could be interesting for concentration of heat sensitive, high value products......Gas hydrate is normally recognized as a troublemaker in the oil and gas industry. However, gas hydrate has some interesting possibilities when used in connection with separation of water. Nordic Sugar has investigated the possibility of using gas hydrates for concentration of sugar juice. The goal...... of the project was to formulate an alternative separation concept, which can replace the traditional water evaporation process in the sugar production. Work with the separation concept showed that gas hydrates can be used for water separation. The process is not suitable for sugar production because of large...

  1. Enhancement of gas desulfurization with hydrated lime at low temperature by the presence of NO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Bausach, M.; Pera-Titus, M.; Fite, C.; Cunill, F.; Izquierdo, J.F.; Tejero, J.; Iborra, M. [University of Barcelona, Barcelona (Spain). Dept. of Chemical Engineering

    2005-11-01

    The effect of NO{sub 2} on the desulfurization reaction of simulated flue gas by Ca(OH){sub 2} was investigated in a fixed-bed reactor at 333-353 K and at relative humidities (RHs) in the range of 30%-70%. NO{sub 2} was determined to be a promoter for SO{sub 2} uptake, because its retention can be increased up to 200%. The effect of NO{sub 2} and O{sub 2} concentration on the kinetics of the desulfurization reaction was surveyed and successfully simulated by means of a deactivation model implemented with an inverse shrinking-core model (DM-ISCM). Solid analyses were also performed to identify the reaction products and provide insight into the chemistry of the process.

  2. THE EFFECT OF FISSURES IN DOLOMITE ROCK MASS ON BLASTING PROJECTS

    Directory of Open Access Journals (Sweden)

    Branko Božić

    1989-12-01

    Full Text Available Rock fractures in the form of fissures are one of more important geological features of a tectonic system. They have an effect on mechanical behaviour of rook masses exposed to the actions of surface forces. For exploitation in dolomite quarries carried out by blasting of deep shot holes it is important to know the system of fissures within a rock mass for the rock brakes along already weakened planes (the paper is published in Croatian.

  3. Distribution of uranium and thorium in dolomitic gravel fill and shale saprolite.

    Science.gov (United States)

    Phillips, D H; Watson, D B

    2015-03-21

    The objectives of this study were to examine (1) the distribution of U and Th in dolomitic gravel fill and shale saprolite, and (2) the removal of uranium from acidic groundwater by dolomitic gravel through precipitation with amorphous basaluminite at the U.S. DOE Oak Ridge Integrated Field Research Challenge (ORIFRC) field site west of the Oak Ridge Y-12 National Security Complex in East Tennessee. Media reactivity and sustainability are a technical concern with the deployment of any subsurface reactive media. Because the gravel was placed in the subsurface and exposed to contaminated groundwater for over 20 years, it provided a unique opportunity to study the solid and water phase geochemical conditions within the media after this length of exposure. This study illustrates that dolomite gravel can remove U from acidic contaminated groundwater with high levels of Al(3+), Ca(2+), NO(3-), and SO4(2-) over the long term. As the groundwater flows through high pH carbonate gravel, U containing amorphous basaluminite precipitates as the pH increases. This is due to an increase in groundwater pH from 3.2 to ∼6.5 as it comes in contact with the gravel. Therefore, carbonate gravel could be considered as a possible treatment medium for removal and sequestration of U and other pH sensitive metals from acidic contaminated groundwater. Thorium concentrations are also high in the carbonate gravel. Thorium generally shows an inverse relationship with U from the surface down into the deeper saprolite. Barite precipitated in the shallow saprolite directly below the dolomitic gravel from barium present in the acidic contaminated groundwater.

  4. Strata-bound Dolomitization in the Eocene Laki Formation, Matyaro Jabal Area Lakhi Range, Sindh, Pakistan

    Directory of Open Access Journals (Sweden)

    Muhammad Waseem Khan

    2015-12-01

    Full Text Available The limestone of Eocene age Laki Formation of Matyaro Jabal area, Lakhi Range SindhPakistan has been studied to see different sedimentary features and diagenetic overprinting. The most diagnostic diagenetic feature of the Laki Formation is the formation of strata bound dolostone over extensive area. The dolostone beds which are separated by non-dolomitic limestone have developed at three different stratigraphic levels whose thickness vary from few centimeters to about 5 meters. Interbedded non dolomitic limestone is characterized by highly fossiliferous to less fossiliferous white chalky limestone with significant secondary porosity. The dolostone beds make lower erosional contact with chalky limestone while upper contact is sharp as well as transitional. The dolostone beds are very hard to soft with well developed dissolution cavities and karstification horizons. As a result of dolostone formation, the primary sedimentary features of rock fabrics and bioclasts are poorly preserved. However, few bioclastic grains show partial preservation with enhanced dissolution and biomoldic porosity. Dolomitization and different porosity types such as; intragranular, vuggy, molidic, intercrystalline, fracture and fenestral have made the limestone of Laki Formation as potential hydrocarbon reservoir rock. The mechanism of stratabound dolostone formation within Laki Formation is due to the mixing of seawater and fresh water with optimum Mg:Ca ratio. The Mg rich sea-water circulated through highly porous and permeable strata which was responsible for stratabound dolostone formation in the Laki Formation. The extrinsic factors such as sea level fluctuations and tectonics also played a vital role for dissolution along with porosity and permeability enhancement followed by dolomitization.

  5. Effect of fertilizer and dolomite applications on growth and yield of tapping rubber trees

    Directory of Open Access Journals (Sweden)

    Issariyaporn Damrongrak

    2015-12-01

    Full Text Available Tropical acid soil used for rubber planting has usually low fertility due to continuous loss of plant nutrient elements by crop removal and leaching. Thus, proper soil improvement in tapping rubber is very essential. This study aimed to measure the growth and yield of 17-year-old rubber trees, chemical properties of soil, and plant nutrient status in the leaf and latex after two years of soil improvement. A randomized complete block of seven treatments: No fertilizer (Control treatment, Chemical fertilizer based on soil analysis according to the recommendation of the Rubber Research Institute (Ch.F, Ch.F+ Dolomite to raise pH up to 6.0 (D, 3 kg per plant of compost (C, Ch.F+C, ½ Ch.F+C and ½ Ch.F+C+D, with three replicates was designed. After two years of giving treatments, it was found that adding full rate of chemical fertilizer based on soil test together with compost or dolomite increased the tree girth increment from the first year to the second year. Rubber yield after soil improvements tended to increase from the beginning to the end of the year, especially with compost application. Increasing of soil fertility was found after soil improvement treatments. However, total N, available P and available K were still lower than optimum levels as well as leaf N and K. Nitrogen in rubber latex after soil improvement treatments was higher than those in the control treatment, which contrasted to those of Ca and Mg. However, fertilizer and dolomite effect on micronutrient elements in rubber leaf and latex were not clear. Thus, fertilizer should be continuously applied at least with the full rate of chemical fertilizer based on soil analysis, and organic fertilizer should be applied to gain some trace elements. Dolomite could also be applied in a very strong acid soil.

  6. Heteroepitaxial growth of cadmium carbonate at dolomite and calcite surfaces: Mechanisms and rates

    Science.gov (United States)

    Callagon, Erika Blanca R.; Lee, Sang Soo; Eng, Peter J.; Laanait, Nouamane; Sturchio, Neil C.; Nagy, Kathryn L.; Fenter, Paul

    2017-05-01

    The systematic variation of rates and the mechanism of cadmium uptake on the (1 0 4) surface of dolomite (CaMg(CO3)2) were investigated using in situ and ex situ atomic force microscopy (AFM), ex situ specular X-ray reflectivity (XR), and ex situ X-ray fluorescence (XRF). Selected experiments were performed on the calcite (CaCO3) (1 0 4) surface for comparison. Aqueous solutions of CdCl2, CaCl2, and NaHCO3, undersaturated with respect to calcite and supersaturated with respect to otavite (CdCO3) and the (CdxCa1-x)CO3 solid solution, were reacted with dolomite surfaces for minutes to days. Calcite substrates were reacted with solutions containing 1-50 μM CdCl2, and with no added Ca or CO3. Thin carbonate films following the Stranski-Krastanov growth mode were observed on both substrates. Specular XR and XRF revealed the formation of nm-thick Cd-rich carbonate films that were structurally ordered with respect to the dolomite (1 0 4) plane. Epitaxial films adopted the calcite crystal structure with a d104-spacing (3.00 Å) larger than those of pure dolomite (2.88 Å) and otavite (2.95 Å) indicating either a solid solution with x ≈ 0.5, or a strained Cd-rich carbonate with a composition near that of otavite. The growth rate r of this phase increases with the initial supersaturation of the solution with respect to the solid solution, βmax , and follows the empirical relationship, as determined from XRF measurements, given by:

  7. Microcracking in calcite and dolomite marble: microstructural influences and effects on properties

    OpenAIRE

    Shushakova, Victoria; Fuller, Edwin; Siegesmund, Siegfried

    2012-01-01

    Microstructure‐based finite-element analysis with a microcracking algorithm was used to simulate an actual degradation phenomenon of marble structures, i.e., microcracking. Both microcrack initiation and crack propagation were characterized, as were their dependence on lattice preferred orientation (LPO), grain shape preferred orientation (SPO), grain size, marble composition (calcite and dolomite) and grain‐boundary fracture toughness. Two LPOs were analyzed: a random orientation distributio...

  8. Criteria for selection of dolomites and catalysts for tar elimination from biomass gasification gas. Kinetic constants

    Energy Technology Data Exchange (ETDEWEB)

    Corella, J.; Narvaez, I.; Orio, A. [Madrid Univ. (Spain). Dept. of Chem. Eng.

    1996-12-31

    Calcined dolomites and commercial steam reforming catalysts are used downstream biomass gasifiers for hot catalytic raw gas cleaning. To further compare these solids under a rigorous basis, a reaction network and a kinetic model are presented. The apparent kinetic constant for the tar reduction is here proposed as a basis of comparison. Tar sampling and analysis, and the units used for the space-time in the catalytic reactor affect the kinetic constants observed. (author) (2 refs.)

  9. Core analyses for selected samples from the Culebra Dolomite at the Waste Isolation Pilot Plant site

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, V.A.; Saulnier, G.J. Jr. (INTERA, Inc., Austin, TX (USA))

    1990-11-01

    Two groups of core samples from the Culebra Dolomite Member of the Rustler Formation at and near the Waste Isolation Pilot Plant were analyzed to provide estimates of hydrologic parameters for use in flow-and-transport modeling. Whole-core and core-plug samples were analyzed by helium porosimetry, resaturation and porosimetry, mercury-intrusion porosimetry, electrical-resistivity techniques, and gas-permeability methods. 33 refs., 25 figs., 10 tabs.

  10. Core analyses for selected samples from the Culebra Dolomite at the Waste Isolation Pilot Plant site

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, V.A.; Saulnier, G.J. Jr. (INTERA, Inc., Austin, TX (USA))

    1990-11-01

    Two groups of core samples from the Culebra Dolomite Member of the Rustler Formation at and near the Waste Isolation Pilot Plant were analyzed to provide estimates of hydrologic parameters for use in flow-and-transport modeling. Whole-core and core-plug samples were analyzed by helium porosimetry, resaturation and porosimetry, mercury-intrusion porosimetry, electrical-resistivity techniques, and gas-permeability methods. 33 refs., 25 figs., 10 tabs.

  11. Well log characterization of natural gas hydrates

    Science.gov (United States)

    Collett, Timothy S.; Lee, Myung W.

    2011-01-01

    In the last 25 years we have seen significant advancements in the use of downhole well logging tools to acquire detailed information on the occurrence of gas hydrate in nature: From an early start of using wireline electrical resistivity and acoustic logs to identify gas hydrate occurrences in wells drilled in Arctic permafrost environments to today where wireline and advanced logging-while-drilling tools are routinely used to examine the petrophysical nature of gas hydrate reservoirs and the distribution and concentration of gas hydrates within various complex reservoir systems. The most established and well known use of downhole log data in gas hydrate research is the use of electrical resistivity and acoustic velocity data (both compressional- and shear-wave data) to make estimates of gas hydrate content (i.e., reservoir saturations) in various sediment types and geologic settings. New downhole logging tools designed to make directionally oriented acoustic and propagation resistivity log measurements have provided the data needed to analyze the acoustic and electrical anisotropic properties of both highly inter-bedded and fracture dominated gas hydrate reservoirs. Advancements in nuclear-magnetic-resonance (NMR) logging and wireline formation testing have also allowed for the characterization of gas hydrate at the pore scale. Integrated NMR and formation testing studies from northern Canada and Alaska have yielded valuable insight into how gas hydrates are physically distributed in sediments and the occurrence and nature of pore fluids (i.e., free-water along with clay and capillary bound water) in gas-hydrate-bearing reservoirs. Information on the distribution of gas hydrate at the pore scale has provided invaluable insight on the mechanisms controlling the formation and occurrence of gas hydrate in nature along with data on gas hydrate reservoir properties (i.e., permeabilities) needed to accurately predict gas production rates for various gas hydrate

  12. Thermal conductivity of hydrate-bearing sediments

    Science.gov (United States)

    Cortes, Douglas D.; Martin, Ana I.; Yun, Tae Sup; Francisca, Franco M.; Santamarina, J. Carlos; Ruppel, Carolyn

    2009-11-01

    A thorough understanding of the thermal conductivity of hydrate-bearing sediments is necessary for evaluating phase transformation processes that would accompany energy production from gas hydrate deposits and for estimating regional heat flow based on the observed depth to the base of the gas hydrate stability zone. The coexistence of multiple phases (gas hydrate, liquid and gas pore fill, and solid sediment grains) and their complex spatial arrangement hinder the a priori prediction of the thermal conductivity of hydrate-bearing sediments. Previous studies have been unable to capture the full parameter space covered by variations in grain size, specific surface, degree of saturation, nature of pore filling material, and effective stress for hydrate-bearing samples. Here we report on systematic measurements of the thermal conductivity of air dry, water- and tetrohydrofuran (THF)-saturated, and THF hydrate-saturated sand and clay samples at vertical effective stress of 0.05 to 1 MPa (corresponding to depths as great as 100 m below seafloor). Results reveal that the bulk thermal conductivity of the samples in every case reflects a complex interplay among particle size, effective stress, porosity, and fluid-versus-hydrate filled pore spaces. The thermal conductivity of THF hydrate-bearing soils increases upon hydrate formation although the thermal conductivities of THF solution and THF hydrate are almost the same. Several mechanisms can contribute to this effect including cryogenic suction during hydrate crystal growth and the ensuing porosity reduction in the surrounding sediment, increased mean effective stress due to hydrate formation under zero lateral strain conditions, and decreased interface thermal impedance as grain-liquid interfaces are transformed into grain-hydrate interfaces.

  13. Thermal conductivity of hydrate-bearing sediments

    Science.gov (United States)

    Cortes, D.D.; Martin, A.I.; Yun, T.S.; Francisca, F.M.; Santamarina, J.C.; Ruppel, C.

    2009-01-01

    A thorough understanding of the thermal conductivity of hydrate-bearing sediments is necessary for evaluating phase transformation processes that would accompany energy production from gas hydrate deposits and for estimating regional heat flow based on the observed depth to the base of the gas hydrate stability zone. The coexistence of multiple phases (gas hydrate, liquid and gas pore fill, and solid sediment grains) and their complex spatial arrangement hinder the a priori prediction of the thermal conductivity of hydrate-bearing sediments. Previous studies have been unable to capture the full parameter space covered by variations in grain size, specific surface, degree of saturation, nature of pore filling material, and effective stress for hydrate-bearing samples. Here we report on systematic measurements of the thermal conductivity of air dry, water- and tetrohydrofuran (THF)-saturated, and THF hydrate-saturated sand and clay samples at vertical effective stress of 0.05 to 1 MPa (corresponding to depths as great as 100 m below seafloor). Results reveal that the bulk thermal conductivity of the samples in every case reflects a complex interplay among particle size, effective stress, porosity, and fluid-versus-hydrate filled pore spaces. The thermal conductivity of THF hydrate-bearing soils increases upon hydrate formation although the thermal conductivities of THF solution and THF hydrate are almost the same. Several mechanisms can contribute to this effect including cryogenic suction during hydrate crystal growth and the ensuing porosity reduction in the surrounding sediment, increased mean effective stress due to hydrate formation under zero lateral strain conditions, and decreased interface thermal impedance as grain-liquid interfaces are transformed into grain-hydrate interfaces. Copyright 2009 by the American Geophysical Union.

  14. Cytotoxic and antibacterial activity of the mixture of olive oil and lime cream in vitro conditions.

    Science.gov (United States)

    Sumer, Zeynep; Yildirim, Gulay; Sumer, Haldun; Yildirim, Sahin

    2013-01-01

    The mixture of olive oil and lime cream has been traditionally used to treat external burns in the region of Hatay/Antakya and middle Anatolia. Olive oil and lime cream have been employed by many physicians to treat many ailments in the past. A limited number of studies have shown the antibacterial effect of olive oil and that it does not have any toxic effect on the skin. But we did not find any reported studies on the mixture of olive oil and lime cream. The aim of this paper is to investigate the cytotoxic and antibacterial activity of olive oil and lime cream individually or/and in combination in vitro conditions, by using disk-diffusion method and in cell culture. The main purpose in using this mixture is usually to clear burns without a trace. Agar overlay, MTT (Cytotoxicity assay) and antibacterial susceptibility tests were used to investigate the cytotoxic and antibacterial activity of olive oil and lime cream. We found that lime cream has an antibacterial activity but also cytotoxic on the fibroblasts. On the other hand olive oil has limited or no antibacterial effect and it has little or no cytotoxic on the fibroblasts. When we combined lime cream and olive oil, olive oil reduced its cytotoxic impact. These results suggest that mixture of olive oil and lime cream is not cytotoxic and has antimicrobial activity.

  15. Self-healing of lime based mortars: Microscopy observations on case studies

    NARCIS (Netherlands)

    Lubelli, B.; Nijland, T.G.; Hees, R.P.J. van

    2011-01-01

    Lime mortars have, up to a certain extent, a self-healing capacity which may contribute to their durability. Self-healing in lime mortars consists of a process of dissolution, transport and re-precipitation of calcium compounds to heal cracks and fissures. The spontaneous occurrence of self-healing

  16. Self-healing of lime based mortars: microscopy observations on case studies

    NARCIS (Netherlands)

    Lubelli, B.; Nijland, T.G.; Van Hees, R.P.J.

    2011-01-01

    Lime mortars have, up to a certain extent, a self-healing capacity which may contribute to their durability. Self-healing in lime mortars consists of a process of dissolution, transport and re-precipitation of calcium compounds to heal cracks and fissures. The spontaneous occurrence of self-healing

  17. Impact of lime, nitrogen and plant species on bacterial community structure in grassland microcosms.

    Science.gov (United States)

    Kennedy, Nabla; Brodie, Eoin; Connolly, John; Clipson, Nicholas

    2004-10-01

    A microcosm-based approach was used to study impacts of plant and chemical factors on the bacterial community structure of an upland acidic grassland soil. Seven perennial plant species typical of both natural, unimproved (Nardus stricta, Agrostis capillaris, Festuca ovina and F. rubra) and fertilized, improved (Holcus lanatus, Lolium perenne and Trifolium repens) grasslands were either left unamended or treated with lime, nitrogen, or lime plus nitrogen in a 75-day glasshouse experiment. Lime and nitrogen amendment were shown to have a greater effect on microbial activity, biomass and bacterial ribotype number than plant species. Liming increased soil pH, microbial activity and biomass, while decreasing ribotype number. Nitrogen addition decreased soil pH, microbial activity and ribotype number. Addition of lime plus nitrogen had intermediate effects, which appeared to be driven more by lime than nitrogen. Terminal restriction fragment length polymorphism (TRFLP) analysis revealed that lime and nitrogen addition altered soil bacterial community structure, while plant species had little effect. These results were further confirmed by multivariate redundancy analysis, and suggest that soil lime and nitrogen status are more important controllers of bacterial community structure than plant rhizosphere effects.

  18. Molecular characterization and pathogenicity assays of Colletotrichum acutatum, causal agent for lime anthracnose in Texas

    Science.gov (United States)

    Several distorted Mexican lime [Citrus aurantiifolia (Christm). Swingle] fruit, leaf, and twig samples with lime anthracnose symptoms were collected from three trees in residential areas of Brownsville, Texas. The causal fungal organism, Colletotrichum acutatum J. H. Simmonds was isolated from leave...

  19. The effect of hydrate saturation on water retention curves in hydrate-bearing sediments

    Science.gov (United States)

    Mahabadi, Nariman; Zheng, Xianglei; Jang, Jaewon

    2016-05-01

    The experimental measurement of water retention curve in hydrate-bearing sediments is critically important to understand the behavior of hydrate dissociation and gas production. In this study, tetrahydrofuran (THF) is selected as hydrate former. The pore habit of THF hydrates is investigated by visual observation in a transparent micromodel. It is confirmed that THF hydrates are not wetting phase on the quartz surface of the micromodel and occupy either an entire pore or part of pore space resulting in change in pore size distribution. And the measurement of water retention curves in THF hydrate-bearing sediments with hydrate saturation ranging from Sh = 0 to Sh = 0.7 is conducted for excess water condition. The experimental results show that the gas entry pressure and the capillary pressure increase with increasing hydrate saturation. Based on the experimental results, fitting parameters for van Genuchten equation are suggested for different hydrate saturation conditions.

  20. Research on the wastewater treatment efficiency in the vertical flow constructed wetland with the dolomite used as the filter media

    OpenAIRE

    Kazakevičienė, Jurgita

    2013-01-01

    Aim of the research The aim of this research was to evaluate the efficiency of the constructed wetlands of vertical filtration with various fractions of dolomite used as the filter media to remove pollutants from the wastewater under the laboratory and industrial conditions and using experimental methods and after the research to prepare the calculation methodology for the filters with dolomite chippings used as the filter media. Objectives of the research In order to ...

  1. Highly efficient CO2 sorbents: development of synthetic, calcium-rich dolomites.

    Science.gov (United States)

    Filitz, Rainer; Kierzkowska, Agnieszka M; Broda, Marcin; Müller, Christoph R

    2012-01-03

    The reaction of CaO with CO(2) is a promising approach for separating CO(2) from hot flue gases. The main issue associated with the use of naturally occurring CaCO(3), that is, limestone, is the rapid decay of its CO(2) capture capacity over repeated cycles of carbonation and calcination. Interestingly, dolomite, a naturally occurring equimolar mixture of CaCO(3) and MgCO(3), possesses a CO(2) uptake that remains almost constant with cycle number. However, owing to the large quantity of MgCO(3) in dolomite, the total CO(2) uptake is comparatively small. Here, we report the development of a synthetic Ca-rich dolomite using a coprecipitation technique, which shows both a very high and a stable CO(2) uptake over repeated cycles of calcination and carbonation. To obtain such an excellent CO(2) uptake characteristic it was found to be crucial to mix the Ca(2+) and Mg(2+) on a molecular level, that is, within the crystalline lattice. For sorbents which were composed of mixtures of microscopic crystals of CaCO(3) and MgCO(3), a decay behavior similar to natural limestone was observed. After 15 cycles, the CO(2) uptake of the best sorbent was 0.51 g CO(2)/g sorbent exceeding the CO(2) uptake of limestone by almost 100%.

  2. Magnesium Production by Silicothermic Reduction of Dolime in Pre-prepared Dolomite Pellets

    Science.gov (United States)

    Fu, Da-Xue; Zhang, Ting-An; Guan, Lu-Kui; Dou, Zhi-He; Wen, Ming

    2016-12-01

    A novel process has been proposed for magnesium production, in which powder materials including dolomite, ferrosilicon, fluorite and binder are mixed to produce pellets. Kinetics of the silicothermic reduction using the pre-prepared dolomite pellets was investigated by a non-isothermal, flowing argon-protected gravimetric technique at a temperature range from 1323 K to 1673 K. The results suggest that the process is controlled by a chemical reaction, with the second-order chemical reaction model providing the best representation of the process. The apparent activation energy was determined to be 280 kJ/mol. Calcium silicide (was found in the pellet after calcinations. The silicothermic process in the pre-prepared dolomite pellets is possibly a solid-liquid reaction since calcium silicide transformed into liquid alloy, which reduced diffusion resistance of silicon during the reduction process. The gas-film mass transfer may have some effect on the reduction kinetics but is not the major rate-limiting step.

  3. Dissolution kinetics and mechanisms at dolomite-water interfaces: effects of electrolyte specific ionic strength.

    Science.gov (United States)

    Xu, Man; Sullivan, Katie; Vanness, Garrett; Knauss, Kevin G; Higgins, Steven R

    2013-01-02

    Elucidating dissolution kinetics and mechanisms at carbonate mineral-water interfaces is essential to many environmental and geochemical processes, including geologic CO(2) sequestration in deep aquifers. In the present work, effects of background electrolytes on dolomite (CaMg(CO(3))(2)) reactivity were investigated by measuring step dissolution rates using in situ hydrothermal atomic force microscopy (HAFM) at 90 °C. Cleaved surfaces of dolomite were exposed to sodium chloride and tetramethylammonium chloride (TMACl) aqueous solutions with ionic strengths (I) ranging from 0 to 0.77 m at pH 4 and pH 9. HAFM results demonstrated that dolomite step retreat rates increased with increasing solution ionic strength and decreasing pH. Comparison of [481] and [441] steps revealed that the anisotropy of [481] and [441] step speeds became significant as solution ionic strength increased, with NaCl exerting more pronounced effects than TMACl for the same I. To interpret the different trends observed for NaCl and TMACl, a dissolution mechanism involving orientation-dependent ion adsorption and consequent edge free energy changes is proposed.

  4. Intermediate-scale tests of sodium interactions with calcite and dolomite aggregate concretes. [LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Randich, E.; Acton, R.U.

    1983-09-01

    Two intermediate-scale tests were performed to compare the behavior of calcite and dolomite aggregate concretes when attacked by molten sodium. The tests were performed as part of an interlaboratory comparison between Sandia National Laboratories and Hanford Engineering Development Laboratories. Results of the tests at Sandia National Laboratories are reported here. The results show that both concretes exhibit similar exothermic reactions with molten sodium. The large difference in reaction vigor suggested by thermodynamic considerations of CO/sub 2/ release from calcite and dolomite was not realized. Penetration rates of 1.4 to 1.7 mm/min were observed for short periods of time with reaction zone temperatures in excess of 800/sup 0/C during the energetic attack. The penetration was not uniform over the entire sodium-concrete contact area. Rapid attack may be localized due to inhomogeneities in the concrete. The chemical reaction zone is less then one cm thick for the calcite concrete but is about seven cm thick for the dolomite concrete.

  5. Z-contrast imaging and ab initio study on "d" superstructure in sedimentary dolomite

    CERN Document Server

    Shen, Zhizhang; Szlufarska, Izabela; Brown, Philip E; Xu, Huifang

    2016-01-01

    Nano-precipitates with tripled periodicity along the c-axis are observed in a Ca-rich dolomite sample from Proterozoic carbonate rocks with "molar tooth" structure. This observation is consistent with previous description of d reflections. High-angle annular dark-field STEM imaging (or Z-contrast imaging) that avoids dynamic diffraction as seen in electron diffraction and high-resolution TEM imaging modes, confirms that d reflections correspond to nanoscale precipitates aligned parallel to (001) of the host dolomite. The lamellae precipitates have a cation ordering sequence of Ca-Ca-Mg-Ca-Ca- Mg along the c direction resulting in a chemical composition of Ca0.67Mg0.33CO3. This superstructure is attributed to the extra or d reflections, thus is referred to as the d superstructure in this study. The structure can be simply described as interstratified calcite/dolomite. The crystal structure of the d superstructure calculated from density functional theory (DFT) has a space group of P31c and has a and c unit-cel...

  6. Experimental observation of permeability changes in dolomite at CO2 sequestration conditions.

    Science.gov (United States)

    Tutolo, Benjamin M; Luhmann, Andrew J; Kong, Xiang-Zhao; Saar, Martin O; Seyfried, William E

    2014-02-18

    Injection of cool CO2 into geothermally warm carbonate reservoirs for storage or geothermal energy production may lower near-well temperature and lead to mass transfer along flow paths leading away from the well. To investigate this process, a dolomite core was subjected to a 650 h, high pressure, CO2 saturated, flow-through experiment. Permeability increased from 10(-15.9) to 10(-15.2) m(2) over the initial 216 h at 21 °C, decreased to 10(-16.2) m(2) over 289 h at 50 °C, largely due to thermally driven CO2 exsolution, and reached a final value of 10(-16.4) m(2) after 145 h at 100 °C due to continued exsolution and the onset of dolomite precipitation. Theoretical calculations show that CO2 exsolution results in a maximum pore space CO2 saturation of 0.5, and steady state relative permeabilities of CO2 and water on the order of 0.0065 and 0.1, respectively. Post-experiment imagery reveals matrix dissolution at low temperatures, and subsequent filling-in of flow passages at elevated temperature. Geochemical calculations indicate that reservoir fluids subjected to a thermal gradient may exsolve and precipitate up to 200 cm(3) CO2 and 1.5 cm(3) dolomite per kg of water, respectively, resulting in substantial porosity and permeability redistribution.

  7. Removal of Phosphate from Synthetic Aqueous Solution by Adsorption with Dolomite from Padalarang

    Directory of Open Access Journals (Sweden)

    Fadjari Lucia Nugroho

    2014-12-01

    Full Text Available The presence of phosphate in wastewaters can cause eutrophication of surface water bodies leading to algal-blooming in the aquatic environment and degradation of water quality. Phosphate removal from wastewaters by conventional biological treatment removes only 10-30% of the phosphate, whilst chemical treatment using precipitants such as calcium or iron salts, although effective, is expensive and produces water-rich sludge which must be further treated. Hence, phosphate removal by adsorption in the form of Ca -phosphate has been proposed as an alternative to the more traditional methods. This study investigated the feasibility of using dolomite–a common sedimentary rock–from Padalarang, West Java, Indonesia as the adsorbent for the removal of phosphate from synthetic aqueous solution. Chemical analysis revealed that the Padalarang dolomite contains 33.6-36.2% CaO. Batch experiments at room temperature indicated that optimum removal of phosphate was achieved at pH 9. At 25°C , where increasing concentrations of phosphate (10–100 mg/L increased phosphate adsorption (2.15-31.3 mg/g by the dolomite. The adsorption of phosphate could be described by the Langmuir isotherm model, with constants Qm= 476.19 mg/g, K L= 0,00106 L/mg and equilibrium parameter (R L: 0.904 – 0.989. Phosphate adsorption by dolomite not only permits its removal but also its potential recovery for reuse.

  8. AVALIAÇÃO DA CALAGEM SOBRE OS PARÂMETROS QUANTITATIVOS, QUALITATIVOS E NUTRICIONAIS DA FORRAGEIRA TANZÂNIA-1 EVALUATION OF THE LIMING ON THE QUANTITATIVE, QUALITATIVE AND NUTRITIONAL PARAMETERS OF THE TANZÂNIA-1 GRASS

    Directory of Open Access Journals (Sweden)

    Renato Sérgio Mota dos Santos

    2007-09-01

    levels of liming were tested (0,3 and 6 t ha-1 of dolomite lime in Dark Red Latosol. The grass production didn’t increase by the lime application, however the largest concentrations of K, Ca, Fe and Mn were observed in plant tissue developed in the limed areas. Detergent Neutral Fiber and Zn presented decreasing tendency while the Cu and P tended to increase with the increment of the liming. The plant height, the number of buds and the productions of dry matter and green mass decreased significantly in response to lime application. In terms of bromatologic aspect, the quality of the forage was improved with the correction of the soil; the largest amounts of gross protein were observed in plants developed in the areas where 3 t ha-1 were applied.

    KEY-WORDS: Forage; liming; savannal soil.

  9. Experimental study on the reuse of spent rapidly hydrated sorbent for circulating fluidized bed flue gas desulfurization.

    Science.gov (United States)

    Li, Yuan; Zheng, Kai; You, Changfu

    2011-11-01

    Rapidly hydrated sorbent, prepared by rapidly hydrating adhesive carrier particles and lime, is a highly effective sorbent for moderate temperature circulating fluidized bed flue gas desulfurization (CFB-FGD) process. The residence time of fine calcium-containing particles in CFB reactors increases by adhering on the surface of larger adhesive carrier particles, which contributes to higher sorbent calcium conversion ratio. The circulation ash of CFB boilers (α-adhesive carrier particles) and the spent sorbent (β and γ-adhesive carrier particles) were used as adhesive carrier particles for producing the rapidly hydrated sorbent. Particle physical characteristic analysis, abrasion characteristics in fluidized bed and desulfurization characteristics in TGA and CFB-FGD systems were investigated for various types of rapidly hydrated sorbent (α, β, and γ-sorbent). The adhesion ability of γ-sorbent was 50.1% higher than that of α-sorbent. The abrasion ratio of β and γ-sorbent was 16.7% lower than that of α-sorbent. The desulfurization abilities of the three sorbent in TGA were almost same. The desulfurization efficiency in the CFB-FGD system was up to 95% at the bed temperature of 750 °C for the β-sorbent.

  10. Arbuscular Mycorrhizal Fungal Communities in the Roots of Maize Lines Contrasting for Al Tolerance Grown in Limed and Non-Limed Brazilian Oxisoil.

    Science.gov (United States)

    Gomes, Eliane A; Oliveira, Christiane A; Lana, Ubiraci G P; Noda, Roberto W; Marriel, Ivanildo E; de Souza, Francisco A

    2015-07-01

    Aluminum (Al) toxicity is one of the greatest limitations to agriculture in acid soils, particularly in tropical regions. Arbuscular mycorrhizal fungi (AMF) can supply plants with nutrients and give protection against Al toxicity. The aim of this work was to evaluate the effects of soil liming (i.e., reducing Al saturation) on the AMF community composition and structure in the roots of maize lines contrasting for Al tolerance. To this end, we constructed four 18S rDNA cloning libraries from L3 (Al tolerant) and L22 (Al sensitive) maize lines grown in limed and non-limed soils. A total of 790 clones were sequenced, 69% belonging to the Glomeromycota phylum. The remaining sequences were from Ascomycota, which were more prominent in the limed soil, mainly in the L3 line. The most abundant AM fungal clones were related to the family Glomeraceae represented by the genera uncultured Glomus followed by Rhizophagus and Funneliformis. However, the most abundant operational taxonomic units with 27% of the Glomeromycota clones was affiliated to genus Racocetra. This genus was present in all the four libraries, but it was predominant in the non-limed soils, suggesting that Racocetra is tolerant to Al toxicity. Similarly, Acaulospora and Rhizophagus were also present mostly in both lines in non-limed soils. The community richness of AMF in the non-limed soils was higher than the limed soil for both lines. The results suggest that the soil Al saturation was the parameter that mostly influences the AMF species composition in the soils in this study.

  11. Characterization of limes (Citrus aurantifolia) grown in Bhutan and Indonesia using high-throughput sequencing.

    Science.gov (United States)

    Penjor, Tshering; Mimura, Takashi; Matsumoto, Ryoji; Yamamoto, Masashi; Nagano, Yukio

    2014-04-30

    Lime [Citrus aurantifolia (Cristm.) Swingle] is a Citrus species that is a popular ingredient in many cuisines. Some citrus plants are known to originate in the area ranging from northeastern India to southwestern China. In the current study, we characterized and compared limes grown in Bhutan (n = 5 accessions) and Indonesia (n = 3 accessions). The limes were separated into two groups based on their morphology. Restriction site-associated DNA sequencing (RAD-seq) separated the eight accessions into two clusters. One cluster contained four accessions from Bhutan, whereas the other cluster contained one accession from Bhutan and the three accessions from Indonesia. This genetic classification supported the morphological classification of limes. The analysis suggests that the properties associated with asexual reproduction, and somatic homologous recombination, have contributed to the genetic diversification of limes.

  12. Pre-desilication and digestion of gibbsitic bauxite with lime in sodium aluminate liquor

    Science.gov (United States)

    Pan, Xiao-lin; Yu, Hai-yan; Dong, Kai-wei; Tu, Gan-feng; Bi, Shi-wen

    2012-11-01

    The effect of lime on the pre-desilication and digestion of gibbsitic bauxite in synthetic sodium aluminate liquor at different temperatures was investigated. The bauxite is comprised of gibbsite, aluminogoethite, hematite, kaolin, quartz, and minor boehmite. Lime increases the desilication efficiency of the bauxite during the pre-desilication process by promoting the conversion of sodalite and cancrinite to hydrogarnet. Desilication reactions during the digestion process promoted by lime result in the loss of Al2O3 entering the red mud, but the amount of aluminogoethite-to-hematite conversion promoted by lime leads to the increase of aluminogoethitic Al2O3 entering the digested liquor. The alumina digestion rate at 245°C is higher than that at 145°C due to the more pronounced conversion of aluminogoethite to hematite. The soda consumption during the digestion process decreases due to lime addition, especially at higher temperatures.

  13. Long-term effects of forest liming on soil, soil leachate, and foliage chemistry in northern Pennsylvania

    Science.gov (United States)

    Robert P. Long; Scott W. Bailey; Stephen B. Horsley; Thomas J. Hall; Bryan R. Swistock; David R. DeWalle

    2015-01-01

    Sugar maple (Acer saccharum Marsh.) decline disease, decreased growth, and regeneration failure have been related to a low supply of Ca and Mg. There is increased interest in augmenting cation availability via liming, but there is little information on the amounts of lime required and the longevity of the lime treatment. A single application of 22.4...

  14. 40 CFR 141.553 - My system practices lime softening-is there any special provision regarding my combined filter...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 22 2010-07-01 2010-07-01 false My system practices lime softening-is... Filter Effluent Requirements § 141.553 My system practices lime softening—is there any special provision regarding my combined filter effluent? If your system practices lime softening, you may...

  15. Action time effect of lime on its depressive ability for pyrite

    Institute of Scientific and Technical Information of China (English)

    Tichang Sun

    2004-01-01

    Two sample groups of bulk concentrates consisting mainly of pyrite and chalcopyrite from Daye and Chenghchao Mines in Hubei Province of China were used to investigate the effect of the action time of lime on its depressive ability for pyrite. The experimental results conducted with different samples and collectors showed that the action time between lime and pyrite markedly influences the depressive ability of lime. The depressive ability of lime increased with the action time increasing. It was also proved that the depressive results obtained at a large lime dosage after a shorter action time are similar to those obtained at a small lime dosage after a longer action time. The increase of depressive ability of lime after a longer action time is because that there are different mechanisms in different action time. The composition on the surface of pyrite acted for different time with lime was studied by using ESCA (Electron Spectroscopic Chemical Analysis). The results showed that iron hydroxide and calcium sulphate formed on the pyrite surface at the presence of lime in the pulp but the amounts of iron hydroxide and calcium sulphate were different at different action time. At the beginning action time the compound formed on the pyrite surface was mainly calcium sulphate and almost no iron hydroxide formed; but with the action time increasing, iron hydroxide formed. The longer the action time, the more iron hydroxide and the less calcium sulphate formed. It was considered that the stronger depressive ability of lime after a longer action time is because more iron hydroxide forms on the pyrite surface.

  16. Synthesis of hydrated lutetium carbonate

    Energy Technology Data Exchange (ETDEWEB)

    Song Liu [South China Univ. of Technology, Dept. of Applied Chemistry, Guangdong (China); Rong-jun Ma [Changsha Research Institute of Minig and Metallurgy, Hunan (China)

    1997-09-01

    Crystalline lutetium carbonate was synthesized for the corresponding chloride using ammonium bicarbonate as precipitant. The chemical analyses suggest that the synthesized lutetium carbonate is a hydrated basic carbonate or oxycarbonate. The X-ray powder diffraction data are presented. The IR data for the compound show the presence of two different carbonate groups. There is no stable intermediate carbonate in the process of thermal decomposition of the lutetium carbonate. (au) 15 refs.

  17. Drilling the Messinian Salinity Crisis as a Model Analogue for Dolomite Deposition at the End of Massive Salt Deposition Events

    Science.gov (United States)

    McKenzie, Judith A.; Aloisi, Giovanni; Anjos, Sylvia; Latgé, Ricardo; Matsuda, Nilo; Bontognali, Tomaso; Vasconcelos, Crisogono

    2015-04-01

    Sedimentologic and stratigraphic studies of the Lower Cretaceous sequence, deposited in the economically important Campos Basin, southeast Brazil, document the occurrence of ~20-m-thick dolomite intervals overlying the "massive salt" megasequences of the Lagoa Feia Formation. This stratigaphic succession marks the Aptian/Albian transition from extreme evaporitic conditions of the Lagoa Feia Formation to shallow marine conditions of the Macaé Formation, related to the early opening of the South Atlantic. The facies change from evaporites to dolomite is interpreted as a product of dolomitization resulting from the refuxing of hypersaline fluids from shallow embayments with intense evaporation (Latgé, 2001). Although the reflux model provides a mechanism to produce fluids with geochemical composition favorable for dolomite precipitation, it cannot account for all of the factors required to promote dolomite precipitation. In this study, we propose a different model to explain the post-evaporite deposition of massive dolomite based on the study of sequences deposited at the end Messinian Salinity Crisis, which were recovered from the deep basins of the Mediterranean Sea during DSDP/ODP drilling campaigns. At most of these deep-water sites, the cored interval contained unusual dolomite deposits overlying the uppermost evaporite sections. For example, the upper Messinian sedimentary sequence at DSDP Site 374 comprises non-fossiliferous dolomitic mudstone overlying dolomitic mudstone/gypsum cycles, which in turn overlie anhydrite and halite (Hsü, Montadert et al., 1978). We postulate that the end Messinian dolomite is a product of microbial activity under extreme hypersaline conditions. In the last 20 years, research into the factors controlling dolomite precipitation under Earth surface conditions has led to the development of new models involving the metabolism of microorganisms and associated biofilms to overcome the kinetic inhibitions associated with primary

  18. Crystallite size distributions of marine gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Klapp, S.A.; Bohrmann, G.; Abegg, F. [Bremen Univ., Bremen (Germany). Research Center of Ocean Margins; Hemes, S.; Klein, H.; Kuhs, W.F. [Gottingen Univ., Gottingen (Germany). Dept. of Crystallography

    2008-07-01

    Experimental studies were conducted to determine the crystallite size distributions of natural gas hydrate samples retrieved from the Gulf of Mexico, the Black Sea, and a hydrate ridge located near offshore Oregon. Synchrotron radiation technology was used to provide the high photon fluxes and high penetration depths needed to accurately analyze the bulk sediment samples. A new beam collimation diffraction technique was used to measure gas hydrate crystallite sizes. The analyses showed that gas hydrate crystals were globular in shape. Mean crystallite sizes ranged from 200 to 400 {mu}m for hydrate samples taken from the sea floor. Larger grain sizes in the hydrate ridge samples suggested differences in hydrate formation ages or processes. A comparison with laboratory-produced methane hydrate samples showed half a lognormal curve with a mean value of 40{mu}m. Results of the study showed that a cautious approach must be adopted when transposing crystallite-size sensitive physical data from laboratory-made gas hydrates to natural settings. It was concluded that crystallite size information may also be used to resolve the formation ages of gas hydrates when formation processes and conditions are constrained. 48 refs., 1 tab., 9 figs.

  19. IMPORTANCE OF HYDRATION IN SPORTS

    Directory of Open Access Journals (Sweden)

    Goran Vasić

    2008-08-01

    Full Text Available Importance of hydration is detrmined by importance of functions of water in the human organism: i.e. regulation of body temperature, transport, excretion of waste materials through urine, digestion of food which is facilititated by saliva and gastric juices, maintenance of flexibility of organs and tissues About 60 % body mass of an adult person (males: 61 %, females: 54 % is made up of water. Water content of a newly born baby reaches 77 %, and it is up to 50 % in adults. It is very important for sportsmen to provide adequate hydration during and after the time of bodily activities. A symptom of water shortage is thirst. However, thirst is a late response of an organism and it occurs when dehydration has already taken place. Minimum in take of fluids in humans should range between one-and-half to two liters. It has been known for a long time that there is no success in sport without proper hydration in a sportsman.

  20. Stable isotope record of coexisting apatite and dolomite in Early Cambrian phosphorites, Meishucun section, South China

    Science.gov (United States)

    Wegwerth, Antje; Struck, Ulrich; Segl, Monika; Vennemann, Torsten W.; Gehlken, Peer-L.; Heubeck, Christoph; Böttcher, Michael E.

    2010-05-01

    The Precambrian-Cambrian transition forms one of the most dramatic time periods in Earth's history, as global changes in tectonics, climate and chemistry in the atmosphere and oceans favoured the worldwide Cambrian Radiation and a concomitant ecosphere revolution. This time interval is paralleled by the first appearance of the widespread giant phosphorites. The well-known Meishucun section (South China), a former candidate section for the Pc-C boundary, documents phosphorite genesis amongst a rapid biodiversification, immediately following the end of the Precambrian in a low-latitude, shallow-water carbonate shelf. This contribution aims to elucidate the relation between simultaneous phosphorite deposition and global environmental conditions at the Pc-C boundary by using stable carbon and oxygen isotope analyses. Accurate determinations of d13C and d18O values may allow conclusions about ancient ocean circulation, paleo-productivity, paleo-temperatures, and most prominently diagenetic processes. The investigated samples from the Meishucun section basically consist of apatite, dolomite, and quartz that may be further devided into a lower and upper phosphorite as well as an overlying dolostone intervall. Additionally, calcite and siderite occur as minor compounds in some samples. Bulk d13C values of the carbonate fraction correlate with dolomite abundance throughout the section ranging from -4 to 1 per mil. Furthermore, several horizons suggest a relation between d13C values and apatite content, implying lower d13C values in apatites compared to coexisting dolomite. A slight negative d13C excursion at the top of the lower phosphorite coincides with the first appearance of small shelly fossils. Corresponding bulk d18O values generally show a stratigraphic-upward trend towards lower values throughout the record with slightly higher values in dolomite-rich sections. This may either indicate a warming trend during deposition, an isotopic shift in sea water composition

  1. Phylogenetic origin of limes and lemons revealed by cytoplasmic and nuclear markers.

    Science.gov (United States)

    Curk, Franck; Ollitrault, Frédérique; Garcia-Lor, Andres; Luro, François; Navarro, Luis; Ollitrault, Patrick

    2016-04-01

    The origin of limes and lemons has been a source of conflicting taxonomic opinions. Biochemical studies, numerical taxonomy and recent molecular studies suggested that cultivated Citrus species result from interspecific hybridization between four basic taxa (C. reticulata,C. maxima,C. medica and C. micrantha). However, the origin of most lemons and limes remains controversial or unknown. The aim of this study was to perform extended analyses of the diversity, genetic structure and origin of limes and lemons. The study was based on 133 Citrus accessions. It combined maternal phylogeny studies based on mitochondrial and chloroplastic markers, and nuclear structure analysis based on the evaluation of ploidy level and the use of 123 markers, including 73 basic taxa diagnostic single nucleotide polymorphism (SNP) and indel markers. The lime and lemon horticultural group appears to be highly polymorphic, with diploid, triploid and tetraploid varieties, and to result from many independent reticulation events which defined the sub-groups. Maternal phylogeny involves four cytoplasmic types out of the six encountered in the Citrus genus. All lime and lemon accessions were highly heterozygous, with interspecific admixture of two, three and even the four ancestral taxa genomes. Molecular polymorphism between varieties of the same sub-group was very low. Citrus medica contributed to all limes and lemons and was the direct male parent for the main sub-groups in combination with C. micrantha or close papeda species (for C. aurata, C. excelsa, C. macrophylla and C. aurantifolia--'Mexican' lime types of Tanaka's taxa), C. reticulata(for C. limonia, C. karna and C. jambhiri varieties of Tanaka's taxa, including popular citrus rootstocks such as 'Rangpur' lime, 'Volkamer' and 'Rough' lemons), C. aurantium (for C. limetta and C. limon--yellow lemon types--varieties of Tanaka's taxa) or the C. maxima × C. reticulate hybrid (for C. limettioides--'Palestine sweet' lime types--and C

  2. Study of Formation Mechanisms of Gas Hydrate

    Science.gov (United States)

    Yang, Jia-Sheng; Wu, Cheng-Yueh; Hsieh, Bieng-Zih

    2015-04-01

    Gas hydrates, which had been found in subsurface geological environments of deep-sea sediments and permafrost regions, are solid crystalline compounds of gas molecules and water. The estimated energy resources of hydrates are at least twice of that of the conventional fossil fuel in the world. Gas hydrates have a great opportunity to become a dominating future energy. In the past years, many laboratory experiments had been conducted to study chemical and thermodynamic characteristics of gas hydrates in order to investigate the formation and dissociation mechanisms of hydrates. However, it is difficult to observe the formation and dissociation of hydrates in a porous media from a physical experiment directly. The purpose of this study was to model the dynamic formation mechanisms of gas hydrate in porous media by reservoir simulation. Two models were designed for this study: 1) a closed-system static model with separated gas and water zones; this model was a hydrate equilibrium model to investigate the behavior of the formation of hydrates near the initial gas-water contact; and 2) an open-system dynamic model with a continuous bottom-up gas flow; this model simulated the behavior of gas migration and studied the formation of hydrates from flowed gas and static formation water in porous media. A phase behavior module was developed in this study for reservoir simulator to model the pressure-volume-temperature (PVT) behavior of hydrates. The thermodynamic equilibriums and chemical reactions were coupled with the phase behavior module to have functions modelling the formation and dissociation of hydrates from/to water and gas. The simulation models used in this study were validated from the code-comparison project proposed by the NETL. According to the modelling results of the closed-system static model, we found that predominated location for the formation of hydrates was below the gas-water contact (or at the top of water zone). The maximum hydrate saturation

  3. SEISMIC STUDIES OF MARINE GAS HYDRATES

    Institute of Scientific and Technical Information of China (English)

    SONG Haibin

    2003-01-01

    We give a brief introduction of developments of seismic methods in the studies of marine gas hydrates. Then we give an example of seismic data processing for BSRs in western Nankai accretionary prism, a typical gas hydrate distribution region. Seismic data processing is proved to be important to obtain better images of BSRs distribution. Studies of velocity structure of hydrated sediments are useful for better understanding the distribution of gas hydrates. Using full waveform inversion, we successfully derived high-resolution velocity model of a double BSR in eastern Nankai Trough area. Recent survey and research show that gas hydrates occur in the marine sediments of the South China Sea and East China Sea.But we would like to say seismic researches on gas hydrate in China are very preliminary.

  4. Development of Alaskan gas hydrate resources

    Energy Technology Data Exchange (ETDEWEB)

    Kamath, V.A.; Sharma, G.D.; Patil, S.L.

    1991-06-01

    The research undertaken in this project pertains to study of various techniques for production of natural gas from Alaskan gas hydrates such as, depressurization, injection of hot water, steam, brine, methanol and ethylene glycol solutions through experimental investigation of decomposition characteristics of hydrate cores. An experimental study has been conducted to measure the effective gas permeability changes as hydrates form in the sandpack and the results have been used to determine the reduction in the effective gas permeability of the sandpack as a function of hydrate saturation. A user friendly, interactive, menu-driven, numerical difference simulator has been developed to model the dissociation of natural gas hydrates in porous media with variable thermal properties. A numerical, finite element simulator has been developed to model the dissociation of hydrates during hot water injection process.

  5. Terahertz Time Domain Spectroscopy for Structure-II Gas Hydrates

    DEFF Research Database (Denmark)

    Takeya, Kei; Zhang, Caihong; Kawayama, Iwao

    2009-01-01

    For the nondestructive inspection of gas hydrates, terahertz (THz) time-domain spectroscopy (TDS) was applied to tetrahydrofuran (THF) hydrate and propane hydrate. The absorption of propane hydrate monotonically increases with frequency, similar to the case of ice, while THF hydrate has a charact...

  6. Clinker mineral hydration at reduced relative humidities

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    1998-01-01

    This report deals with gas phase hydration of pure cement clinker minerals at reduced relative humidities. This is an important subject in relation to modern high performance concrete which may self-desiccate during hydration. In addition the subject has relevance to storage stability where...... prehydration may occur. In the report both theoretical considerations and experimental data are presented. It is suggested that the initiation of hydration during water vapour exposure is nucleation controlled....

  7. Double mixing fly ash and lime powder's influence on the compressive strength of concrete%粉煤灰石灰粉对再生细骨料混凝土抗压强度的影响

    Institute of Scientific and Technical Information of China (English)

    贾广测; 吴相豪; 朱涛

    2015-01-01

    Add lime to regeneration of fly ash concrete, can stimulate the activity of fly ash, promote the secondary hydration of fly ash. This topic proposed through experiment explore single mixing fly ash, double mixing fly ash and lime powder on the compressive strength of recycled fine aggregate concrete are studied, for the recycled fine aggregate concrete to provide theoretical basis for the popularization and application. Research process, the test is divided into two kinds of conditions: the first condition for single mixing fly ash; The second condition for double mixing fly ash and lime. Experiments show that: when only mixing fly ash, with the increasing dosage of fly ash, the compressive strength is first increases then decreases, and the content was 20%, the compressive strength is the largest. Double mixing fly ash and lime powder, the early compressive strength increases rapidly and the compressive strength increases with the increase of the dosage of lime powder is first reduced, after lime powder content was 4%, the compressive strength of recycled fine aggregate concrete is the largest.?%将石灰粉加入再生粉煤灰混凝土中,可激发粉煤灰的活性,促进粉煤灰的"二次水化".本课题拟通过试验探索单掺粉煤灰、双掺粉煤灰和石灰粉对再生细骨料混凝土抗压强度的影响规律,为再生细骨料混凝土的推广应用提供理论依据.研究过程中,试验分两种工况:第一种工况为单掺粉煤灰;第二种工况为双掺粉煤灰和石灰粉.实验表明:单掺粉煤灰时,随着粉煤灰掺量增加,抗压强度是先增大后减小,且掺量为20%时,抗压强度最大.双掺粉煤灰和石灰粉时,早期抗压强度增大较快,抗压强度随石灰粉掺量的增加是先增加后减小,石灰粉掺量为4%时,再生细骨料混凝土的抗压强度最大.

  8. Effect of adding natural pozzolana on geotechnical properties of lime-stabilized clayey soil

    Institute of Scientific and Technical Information of China (English)

    Aref al-Swaidani; Ibrahim Hammoud; Ayman Meziab

    2016-01-01

    Clayey soils in Syria cover a total area of more than 20,000 km2 of the country, most of which are located in the southwestern region. In many places of the country, the clayey soils caused severe damage to infrastructures. Extensive studies have been carried out on the stabilization of clayey soils using lime. Syria is rich in both lime and natural pozzolana. However, few works have been conducted to investigate the influence of adding natural pozzolana on the geotechnical properties of lime-treated clayey soils. The aim of this paper is to understand the effect of adding natural pozzolana on some geotechnical properties of lime-stabilized clayey soils. Natural pozzolana and lime are added to soil within the range of 0%-20%and 0%-8%, respectively. Consistency, compaction, California bearing ratio (CBR) and linear shrinkage properties are particularly investigated. The test results show that the investigated properties of lime-treated clayey soils can be considerably enhanced when the natural pozzolana is added as a stabiliz-ing agent. Analysis results of scanning electron microscopy (SEM) and energy-dispersive X-ray spec-troscopy (EDX) show significant changes in the microstructure of the treated clayey soil. A better flocculation of clayey particles and further formation of cementing materials in the natural pozzolana-lime-treated clayey soil are clearly observed.

  9. A new look at liming as an approach to accelerate recovery from acidic deposition effects.

    Science.gov (United States)

    Lawrence, Gregory B; Burns, Douglas A; Riva-Murray, Karen

    2016-08-15

    Acidic deposition caused by fossil fuel combustion has degraded aquatic and terrestrial ecosystems in North America for over four decades. The only management option other than emissions reductions for combating the effects of acidic deposition has been the application of lime to neutralize acidity after it has been deposited on the landscape. For this reason, liming has been a part of acid rain science from the beginning. However, continued declines in acidic deposition have led to partial recovery of surface water chemistry, and the start of soil recovery. Liming is therefore no longer needed to prevent further damage, so the question becomes whether liming would be useful for accelerating recovery of systems where improvement has lagged. As more is learned about recovering ecosystems, it has become clear that recovery rates vary with watershed characteristics and among ecosystem components. Lakes appear to show the strongest recovery, but recovery in streams is sluggish and recovery of soils appears to be in the early stages. The method in which lime is applied is therefore critical in achieving the goal of accelerated recovery. Application of lime to a watershed provides the advantage of increasing Ca availability and reducing or preventing mobilization of toxic Al, an outcome that is beneficial to both terrestrial and aquatic ecosystems. However, the goal should not be complete neutralization of soil acidity, which is naturally produced. Liming of naturally acidic areas such as wetlands should also be avoided to prevent damage to indigenous species that rely on an acidic environment. Published by Elsevier B.V.

  10. Application of organic compounds to lime and limestone products; Yuki kagobutsu wo riyoshita sekkaikei zairyo

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, H. [Okutama Kogyo Co. Ltd., Tokyo (Japan)

    1998-11-01

    Outlined herein are lime-based composites with organic compounds by classifying them into three groups of limestone-, unslacked lime- and slacked lime-based. Calcium carbonate, being hydrophilic on the surface, is sparingly wettable with hydrophobic polymers. It is therefore surface-modified with organic compounds to secure filler surfaces compatible and strongly interactive with polymers. These organic compounds include fatty acids and their salts, rosin, amines, esters, surfactants, wax, monomers and polymers. Composites of resins with calcium carbonate are limited to plastics for common use. PTFE resin containing cement or lime as the soil stabilizer has shown good results to prevent dust for the soil improvement method which uses soil of the site. Also described herein are compositing researches to increase strength of carbonated and hardened slacked lime by impregnating it with MMA, and development of slacked lime having an approximately 3 times larger specific surface area than slacked lime of special grade to remove dry, acidic emissions exhausted from garbage incinerators. 15 refs., 7 figs., 3 tabs.

  11. Soil acidification and the importance of liming agricultural soils with particular reference to the United Kingdom.

    Science.gov (United States)

    Goulding, K W T

    2016-09-01

    Soil acidification is caused by a number of factors including acidic precipitation and the deposition from the atmosphere of acidifying gases or particles, such as sulphur dioxide, ammonia and nitric acid. The most important causes of soil acidification on agricultural land, however, are the application of ammonium-based fertilizers and urea, elemental S fertilizer and the growth of legumes. Acidification causes the loss of base cations, an increase in aluminium saturation and a decline in crop yields; severe acidification can cause nonreversible clay mineral dissolution and a reduction in cation exchange capacity, accompanied by structural deterioration. Soil acidity is ameliorated by applying lime or other acid-neutralizing materials. 'Liming' also reduces N2O emissions, but this is more than offset by CO 2 emissions from the lime as it neutralizes acidity. Because crop plants vary in their tolerance to acidity and plant nutrients have different optimal pH ranges, target soil pH values in the UK are set at 6.5 (5.8 in peaty soils) for cropped land and 6.0 (5.3 in peaty soils) for grassland. Agricultural lime products can be sold as 'EC Fertiliser Liming Materials' but, although vital for soil quality and agricultural production, liming tends to be strongly influenced by the economics of farming. Consequently, much less lime is being applied in the UK than required, and many arable and grassland soils are below optimum pH.

  12. Defining reactive sites on hydrated mineral surfaces: Rhombohedral carbonate minerals

    Science.gov (United States)

    Villegas-Jiménez, Adrián; Mucci, Alfonso; Pokrovsky, Oleg S.; Schott, Jacques

    2009-08-01

    Despite the success of surface complexation models (SCMs) to interpret the adsorptive properties of mineral surfaces, their construct is sometimes incompatible with fundamental chemical and/or physical constraints, and thus, casts doubts on the physical-chemical significance of the derived model parameters. In this paper, we address the definition of primary surface sites (i.e., adsorption units) at hydrated carbonate mineral surfaces and discuss its implications to the formulation and calibration of surface equilibria for these minerals. Given the abundance of experimental and theoretical information on the structural properties of the hydrated (10.4) cleavage calcite surface, this mineral was chosen for a detailed theoretical analysis of critical issues relevant to the definition of primary surface sites. Accordingly, a single, generic charge-neutral surface site ( tbnd CaCO 3·H 2O 0) is defined for this mineral whereupon mass-action expressions describing adsorption equilibria were formulated. The one-site scheme, analogous to previously postulated descriptions of metal oxide surfaces, allows for a simple, yet realistic, molecular representation of surface reactions and provides a generalized reference state suitable for the calculation of sorption equilibria for rhombohedral carbonate minerals via Law of Mass Action (LMA) and Gibbs Energy Minimization (GEM) approaches. The one-site scheme is extended to other rhombohedral carbonate minerals and tested against published experimental data for magnesite and dolomite in aqueous solutions. A simplified SCM based on this scheme can successfully reproduce surface charge, reasonably simulate the electrokinetic behavior of these minerals, and predict surface speciation agreeing with available spectroscopic data. According to this model, a truly amphoteric behavior is displayed by these surfaces across the pH scale but at circum-neutral pH (5.8-8.2) and relatively high ΣCO 2 (⩾1 mM), proton/bicarbonate co

  13. Luminescence quartz dating of lime mortars. A first research approach.

    Science.gov (United States)

    Zacharias, N; Mauz, B; Michael, C T

    2002-01-01

    Lime mortars mixed with sand are well suited for connecting structural materials, like stones and bricks, due to the mechanical properties this material exhibits. Their extensive use in architectural and decorative works during the last 4000 years motivated the introduction of the 'Luminescence clock' for age determination of mortars. The same principles as for quartz optically stimulated luminescence (OSL) dating of sediments were applied for age estimation of a mortar fragment removed from a Byzantine church monument dated by archaeological means to 1050-1100 years ago (the first half of the 10th century). The OSL from the quartz was monitored under blue light stimulation and UV detection, using a single-aliquot-regenerative-dose protocol. The quartz-OSL dating of the mortar resulted in 870 +/- 230 a. TL polymineral fine grain dating was also performed on a brick fragment which was connected to the mortar, resulting in a TL age of 1095 +/- 190 a.

  14. Shock wave propagation in soda lime glass using optical shadowgraphy

    Indian Academy of Sciences (India)

    PRASAD Y B S R; BARNWAL S; NAIK P A; YADAV Y; PATIDAR R; KAMATH M P; UPADHYAY A; BAGCHI S; KUMAR A; JOSHI A S; GUPTA P D

    2016-07-01

    Propagation of shock waves in soda lime glass, which is a transparent material, has been studied using the optical shadowgraphy technique. The time-resolved shock velocity information has been obtained (1) in single shot, using the chirped pulse shadowgraphy technique, with a temporal resolution of tens of picoseconds and (2) in multiple shots, using conventional snapshot approach, with a second harmonic probe pulse. Transient shock velocities of $(5–7) \\times 10^{6}$ cm/s have been obtained. The scaling of the shock velocity with intensity in the $2 \\times 10^{13}–10^{14}$ W/cm$^2$ range has been obtained. The shock velocity is observed to scale with laser intensity as $I^{0.38}$. The present experiments also show the presence of ionization tracks, generated probably due to X-ray hotspots from small-scale filamentation instabilities. The results and various issues involved in these experiments are discussed

  15. Fragrance mix reactions and lime allergic contact dermatitis.

    Science.gov (United States)

    Swerdlin, Amy; Rainey, David; Storrs, Frances J

    2010-01-01

    Allergic contact dermatitis due to citrus fruits is rare, but has been reported in cooks and bartenders. We report an interesting case of a bartender with hand dermatitis who had an allergic contact sensitivity to lime peel, fragrance mix I, and fragrance mix II. Most reported cases of citrus peel allergy are due to d-limonene, which makes up the majority of the peel oil. However, our patient had an allergic reaction to geraniol, which is a minor component of the peel oil and is present in fragrance mix I. It is important to consider a contact sensitivity to citrus in patients who have positive reactions to fragrance mix I and II and who are occupationally exposed to citrus fruits. An initial positive reaction to fragrance mixes should prompt further testing to citrus in these individuals.

  16. STRESS RELAXATION AND RELIABILITY EVALUATION OF SODA-LIME GLASS

    Institute of Scientific and Technical Information of China (English)

    Y.W.Bao; Y.F.Han; F.T.Gong

    2004-01-01

    Stress relaxation of glass is a dualism effect, it often lead to strength degradation in strengthened glass, but on the other hand, it improves the reliability and stressuniformity of glasses. In this work, stress relaxation of soda-lime glass was investigated using three-point bending tests at 400-560℃ which is near the brittle to ductile transition temperature, for enhancing the safety of glass productions and exploring the most economic anneal process. The experimental results show that the speed of stress relaxation increases but the ultimate stress decreases with increasing temperature. The stress uniformity of the glass samples before and after anneal was examined using spherical indentation at arranged testing points. It indicates that the scatter of the local strength measured by the Hertzian indentation is smaller in the anneal glass than in initial specimen, so that the estimated Weibull modulus for the anneal specimen is higher. Furthermore, the strength evaluation by Hertzian indentation and statistical analysis was presented.

  17. STATISTICAL ANALYSIS OF A SODA LIME GLASS THERMAL SHOCK RESISTANCE

    Directory of Open Access Journals (Sweden)

    Gilbert FANTOZZI

    2011-09-01

    Full Text Available Comparatively to the as received soda lime glass samples, the strength distribution after thermal shocks showed the appearance of a second branch in the Weibull curves. This branch is observed for temperature differences (ΔT equal or higher than the critical temperature difference (ΔTc for both water and motor oil cooling baths. The dispersion is more spread out in these two baths in comparison with the olive oil bath probably because of more pronounced slow crack growth effect. The Weibull modulus varies according to the used cooling bath and the considered temperature difference. In the case of thermal shock caused by air blast cooling at T = 20°C, a bimodal distribution is observed for only the critical state. The initial cracking time, obtained by acoustic emission, corresponds to the unstable propagation of the most critical defect. The number of cracks induced by thermal shock is proportional to the number of acoustic events.

  18. Prediction of Refrigerant Gas Hydrates Formation Conditions

    Institute of Scientific and Technical Information of China (English)

    Deqing Liang; Ruzhu Wang; Kaihua Guo; Shuanshi Fan

    2001-01-01

    A fugacity model was developed for prediction of mixed refrigerant gas hydrates formation conditions based on the molecule congregation and solution theories. In this model, g as hydrates were regarded as non-ideal solid solution composed of water groups and guest molecules, and the expressions of fugacity of guest molecules in hydrate phase was proposed accordingly. It has been shown that the developed model can indicate successfully the effect of guest-guest molecule interaction. The results showed that the model can describe better the characteristics of phase equilibrium of mixed refrigerant gas hydrates and predictions are in good agreement with experimental data.

  19. Desalination utilizing clathrate hydrates (LDRD final report).

    Energy Technology Data Exchange (ETDEWEB)

    Simmons, Blake Alexander; Bradshaw, Robert W.; Dedrick, Daniel E.; Cygan, Randall Timothy (Sandia National Laboratories, Albuquerque, NM); Greathouse, Jeffery A. (Sandia National Laboratories, Albuquerque, NM); Majzoub, Eric H. (University of Missouri, Columbia, MO)

    2008-01-01

    Advances are reported in several aspects of clathrate hydrate desalination fundamentals necessary to develop an economical means to produce municipal quantities of potable water from seawater or brackish feedstock. These aspects include the following, (1) advances in defining the most promising systems design based on new types of hydrate guest molecules, (2) selection of optimal multi-phase reactors and separation arrangements, and, (3) applicability of an inert heat exchange fluid to moderate hydrate growth, control the morphology of the solid hydrate material formed, and facilitate separation of hydrate solids from concentrated brine. The rate of R141b hydrate formation was determined and found to depend only on the degree of supercooling. The rate of R141b hydrate formation in the presence of a heat exchange fluid depended on the degree of supercooling according to the same rate equation as pure R141b with secondary dependence on salinity. Experiments demonstrated that a perfluorocarbon heat exchange fluid assisted separation of R141b hydrates from brine. Preliminary experiments using the guest species, difluoromethane, showed that hydrate formation rates were substantial at temperatures up to at least 12 C and demonstrated partial separation of water from brine. We present a detailed molecular picture of the structure and dynamics of R141b guest molecules within water cages, obtained from ab initio calculations, molecular dynamics simulations, and Raman spectroscopy. Density functional theory calculations were used to provide an energetic and molecular orbital description of R141b stability in both large and small cages in a structure II hydrate. Additionally, the hydrate of an isomer, 1,2-dichloro-1-fluoroethane, does not form at ambient conditions because of extensive overlap of electron density between guest and host. Classical molecular dynamics simulations and laboratory trials support the results for the isomer hydrate. Molecular dynamics simulations

  20. Efeitos da calagem em semedura direta de milho Effect of lime application on no-tillage corn

    Directory of Open Access Journals (Sweden)

    Josinei Antonio Tissi

    2004-12-01

    yet. To evaluate these effects on maize and its reflexes on grain yield performance, a field trial was carried out on a dystrophic clayey Rhodic Hapludox, previously managed under no-tillage for six years, at Tibagi, State of Paraná, Brazil. The experimental design was a randomized complete block with four replications, using 44.8 m² plots. The treatments consisted of four liming rates (0, 1, 2 and 3 t.ha-1, pure CaCO3 equivalents which represented 1/3, 2/3 and the total amount calculated for the soil to reach a base saturation of 70%, in the 0-20 cm layer. Dolomitic limestone (27% of CaO, 20% of MgO and 85% of ECCE was broadcast-applied to the soil surface without incorporation. After 22 months, lime application increased soil pH in CaCl2 0.01 mol.L-1, exchangeable Ca and Mg, and base saturation, and reduced H + Al and exchangeable Al at the superficial layer (0-10 cm. It also increased exchangeable Ca and decreased exchangeable Al at the subsoil (20-40 cm. Liming did not significantly affect length and relative distribution of corn root at the 40 cm depth, reduced average root radius and increased plant uptake of P, Ca, Mg, and S, with no significant effects on grain yields. Surface lime application did not affect Cu, Fe, Mn and Zn concentrations in the soil and leaves or plant uptake of these micronutrients.

  1. Low Velocity Sphere Impact of a Soda Lime Silicate Glass

    Energy Technology Data Exchange (ETDEWEB)

    Wereszczak, Andrew A [ORNL; Fox, Ethan E [ORNL; Morrissey, Timothy G [ORNL; Vuono, Daniel J [ORNL

    2011-10-01

    This report summarizes TARDEC-sponsored work at Oak Ridge National Laboratory (ORNL) during the FY11 involving low velocity (< 30 m/s or < 65 mph) ball impact testing of Starphire soda lime silicate glass. The intent was to better understand low velocity impact response in the Starphire for sphere densities that bracketed that of rock. Five sphere materials were used: borosilicate glass, soda-lime silicate glass, steel, silicon nitride, and alumina. A gas gun was fabricated to produce controlled velocity delivery of the spheres against Starphire tile targets. Minimum impact velocities to initiate fracture in the Starphire were measured and interpreted in context to the kinetic energy of impact and the elastic property mismatch between the any of the five sphere-Starphire-target combinations. The primary observations from this low velocity (< 30 m/s or < 65 mph) testing were: (1) Frictional effects contribute to fracture initiation. (2) Spheres with a lower elastic modulus require less force to initiate fracture in the Starphire than spheres with a higher elastic modulus. (3) Contact-induced fracture did not initiate in the Starphire SLS for impact kinetic energies < 150 mJ. Fracture sometimes initiated or kinetic energies between {approx} 150-1100 mJ; however, it tended to occur when lower elastic modulus spheres were impacting it. Contact-induced fracture would always occur for impact energies > 1100 mJ. (4) The force necessary to initiate contact-induced fracture is higher under dynamic or impact conditions than it is under quasi-static indentation conditions. (5) Among the five used sphere materials, silicon nitride was the closest match to 'rock' in terms of both density and (probably) elastic modulus.

  2. Effects of Bamboo Leaf Ash on Lime Stabilized Lateritic Soil for Highway Construction

    Directory of Open Access Journals (Sweden)

    S.S. Babajide

    2011-04-01

    Full Text Available This research determined the effects of bamboo leaf ash on lime stabilized lateritic soil for highway construction. It was necessary to utilize the properties of waste materials such as bamboo leaf in order to determine its usefulness as a possible complement stabilizer for lime and hence reduce highway construction cost. The three samples A, B and C used in this study were collected from different locations in Ile-Ife, Nigeria. Preliminary tests such as the natural moisture content, specific gravity, grain size analysis and Atterberg’s limits were performed on them at their natural states and when stabilized with optimum percentages of lime. Engineering tests such as compaction, California Bearing Ratio (CBR and undrained traixial were also performed on them at their natural states, when stabilized with the optimum lime percentages and when Bamboo Leaf Ash (BLA was introduced at 2, 4 and 6% to the samples. The results of the strength tests showed that BLA improved the strengths of all the lime stabilized samples. The unsoaked CBR values increased from 4-11, 2-10 and 2-11%, respectively in lime stabilized samples A, B and C with the addition of BLA. The shear strengths also increased substantially, from 42.16 to 398.96 kN/m2, 42.96 to 146.84 kN/m2 and 197.48 to 365.90 kN/m2, respectively with the addition of BLA to the lime stabilized samples. It was therefore concluded that BLA will further increase the strength of lime stabilized lateritic soil for highway construction since it was found as an effective complement for lime in soil stabilization.

  3. Nutrient leaching potential following application of papermill lime-sludge to an acidic clay soil

    Directory of Open Access Journals (Sweden)

    S. C. Vettorazzo

    2001-09-01

    Full Text Available This experiment was carried out under greenhouse conditions with soil pots during 210 days, to evaluate the effect of calcitic papermill lime-sludge application (at the rates 0, 773, 1.547, and 2.320 mg kg-1 or respective equivalents to control, 2, 4, and 6 t ha-1, on chemical composition of soil leachate and its effects on eucalypt growth and yield. Highest soil leachate pH, SO4, and Na concentrations occurred in the 4 and 6 t ha-1 treatments. Soil leachate nitrate concentrations decreased with increasing lime-sludge rate. Soil leachate phosphate remained low (below the detection limit in all treatments until 120 days, while the concentration increased in the lime-sludge treatments at 210 days (last sampling in about 600 mg L-1. Lime-sludge decreased leachate Mg concentration, but had no significant effect among rates. Soil leachate Ca, K, B, Cu, Fe, and Zn did not change significantly for any lime-sludge application rates. The maximum NO3, Ca, Mg, K, and Na concentrations in the soil leachate occurred at 60 days after lime-sludge application (leaching equivalent to 1 pore volume, but for pH and SO4, the maximum occurred at 210 days (leaching equivalent to 4 pore volumes. Lime-sludge application decreased the concentration of exchangeable Al in the soil. Plant diameter growth and dry matter yield were increased with increasing lime-sludge rate. Beneficial effects on mineral nutrition (P, K, Ca, B, and Zn of eucalypts were also obtained by the application of 4 and 6 t ha-1 of lime-sludge.

  4. Waters of Hydration of Cupric Hydrates: A Comparison between Heating and Absorbance Methods

    Science.gov (United States)

    Barlag, Rebecca; Nyasulu, Frazier

    2011-01-01

    The empirical formulas of four cupric hydrates are determined by measuring the absorbance in aqueous solution. The Beer-Lambert Law is verified by constructing a calibration curve of absorbance versus known Cu[superscript 2+](aq) concentration. A solution of the unknown hydrate is prepared by using 0.2-0.3 g of hydrate, and water is added such…

  5. Genetic variation assessment of acid lime accessions collected from south of Iran using SSR and ISSR molecular markers.

    Science.gov (United States)

    Sharafi, Ata Allah; Abkenar, Asad Asadi; Sharafi, Ali; Masaeli, Mohammad

    2016-01-01

    Iran has a long history of acid lime cultivation and propagation. In this study, genetic variation in 28 acid lime accessions from five regions of south of Iran, and their relatedness with other 19 citrus cultivars were analyzed using Simple Sequence Repeat (SSR) and Inter-Simple Sequence Repeat (ISSR) molecular markers. Nine primers for SSR and nine ISSR primers were used for allele scoring. In total, 49 SSR and 131 ISSR polymorphic alleles were detected. Cluster analysis of SSR and ISSR data showed that most of the acid lime accessions (19 genotypes) have hybrid origin and genetically distance with nucellar of Mexican lime (9 genotypes). As nucellar of Mexican lime are susceptible to phytoplasma, these acid lime genotypes can be used to evaluate their tolerance against biotic constricts like lime "witches' broom disease".

  6. Chemo-physical evolution and microstructure features of lime treated soils

    Directory of Open Access Journals (Sweden)

    Russo Giacomo

    2016-01-01

    Full Text Available In the paper some results on the effects of chemo-physical evolution of clay-lime-water suspensions on the microstructure of a lime treated kaolin have been presented. A multi-scale investigation on the sedimentation behaviour of clay suspensions under different pore water chemistry has been developed highlighting the chemo-physical mechanisms controlling particle arrangement and the soil fabric formation. The results evidenced the key role of ionic exchange in the short term on the microstructure features of the lime treated soil.

  7. Primary Evaporites for the Messinian Salinity Crisis: the shallow gypsum vs. deep dolomite formation paradox solved

    Science.gov (United States)

    De Lange, Gert J.; Krijgsman, Wout

    2014-05-01

    The Messinian Salinity Crisis (MSC) is a dramatic event that took place ~ 5.9 Ma ago, and resulted in the deposition of 0.3-3 km thick evaporites at the Mediterranean seafloor. A considerable and long-lasting controversy existed on the modes of their formation. During the CIESM Almeria Workshop a consensus was reached on several aspects. In addition, remaining issues to be solved were identified, such as for the observed shallow gypsum versus deep dolostone deposits for the early phase of MSC. The onset of MSC is marked by deposition of gypsum/sapropel-like alternations, thought to relate to arid/humid climate conditions. Gypsum precipitation only occurred at marginal settings, while dolomite containing rocks have been reported from deeper settings. A range of potential explanations have been reported, most of which cannot satisfactorily explain all observations. Biogeochemical processes during MSC are poorly understood and commonly neglected. These may, however, explain that different deposits formed in shallow versus deep environments without needing exceptional physical boundary conditions for each. We present here a unifying mechanism in which gypsum formation occurs at all shallow water depths but its preservation is mostly limited to shallow sedimentary settings. In contrast, ongoing anoxic organic matter (OM) degradation processes in the deep basin result in the formation of dolomite. Gypsum precipitation in evaporating seawater takes place at 3-7 times concentrated seawater; seawater is always largely oversaturated relative to dolomite but its formation is thought to be inhibited by the presence of dissolved sulphate. Thus the conditions for formation of gypsum exclude those for the formation of dolomite and vice versa. Another process that links the saturation states of gypsum and dolomite is that of OM degradation by sulphate reduction. In stagnant deep water, oxygen is rapidly depleted through OM degradation, then sulphate becomes the main oxidant for OM

  8. Hydration in soccer: a review

    Directory of Open Access Journals (Sweden)

    Monteiro Cristiano Ralo

    2003-01-01

    Full Text Available Hydration should be considered before, during and after the exercise. This review intends to approach the main points of hydration process in soccer. The replacement of fluids during exercise is proportional to some factors, such as: exercise intensity; climatic conditions; the athlete's acclimatization; the athlete's physical conditioning; physiologic individual characteristics and the player's biomechanics. Performance is improved when players ingest not only water but also carbohydrate. The rates that carbohydrate and water are absorbed by the organism are limited by the rates of gastric emptying and intestinal absorption. The composition of drinks offered to the players should be influenced by the relative importance of the need of supplying carbohydrates or water; it should be remembered that the depletion of carbohydrate can result in fatigue and decrease of performance, but it is not usually a life-threatening condition. The addition of carbohydrate in these drinks increases the concentrations of blood glucose, increases the use of external fuel through the increase of the glucose oxidation in the muscles and it spares muscle glycogen. So, the ingestion of carbohydrate before and during the exercise can delay the emergence of fatigue and increase the players' performance. Several tactics can be used to avoid dehydration, like hyperhydration before exercise and player's acclimatization. The ideal situation to restore the player's fluid losses is between the sessions of exercises. Since soccer is a sport with quite peculiar characteristics related to hydration, the players should be concerned and educated about the importance of fluid ingestion before, during and after the exercise.

  9. Hydration behaviour of polyhydroxylated fullerenes

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Zavala, J G [Departamento de Ciencias Exactas y Tecnologicas, Centro Universitario de Los Lagos, Universidad de Guadalajara, Enrique Diaz de Leon S/N, 47460 Jalisco (Mexico); Barajas-Barraza, R E [Departamento de Matematicas y Fisica, Instituto Tecnologico y de Estudios Superiores de Occidente, Periferico Sur, Manuel Gomez MorIn No 8585, 45604 Jalisco (Mexico); Padilla-Osuna, I; Guirado-Lopez, R A, E-mail: jgrz@culagos.udg.mx, E-mail: ebarajas@iteso.mx, E-mail: ismael@ifisica.uaslp.mx, E-mail: guirado@ifisica.uaslp.mx [Instituto de Fisica ' Manuel Sandoval Vallarta' , Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, 78000 San Luis Potosi (Mexico)

    2011-10-28

    We have performed semi-empirical as well as density functional theory calculations in order to analyse the hydration properties of both bare C{sub 60} and highly hydroxylated C{sub 60}(OH){sub 26} fullerenes. In all of our calculations, a total of 42 and 98 water molecules are always surrounding our here-considered carbon nanostructures. We found different wetting properties as a function of the chemical composition and structure of the OH-molecular over-layer covering the fullerene surface. In the case of bare C{sub 60}, water adsorption reveals that the H{sub 2}O species are not uniformly arranged around the carbon network but rather forms water droplets of different sizes, clearly revealing the hydrophobic nature of the C{sub 60} structure. In contrast, in the polyhydroxylated C{sub 60}(OH){sub 26} fullerenes, the degree of wetting is strongly influenced by the precise location of the hydroxyl groups. We found that different adsorbed configurations for the OH-molecular coating can lead to the formation of partially hydrated or completely covered C{sub 60}(OH){sub 26} compounds, a result that could be used to synthesize fullerene materials with different degrees of wettability. By comparing the relative stability of our hydroxylated structures in both bare and hydrated conditions we obtain that the energy ordering of the C{sub 60}(OH){sub 26} isomers can change in the presence of water. The radial distribution function of our hydrated fullerenes reveals that water near these kinds of surfaces is densely packed. In fact, by counting the number of H{sub 2}O molecules which are adsorbed, by means of hydrogen bonds, to the surface of our more stable C{sub 60}(OH){sub 26} isomer, we found that it varies in the range of 5-10, in good agreement with experiments. Finally, by comparing the calculated optical absorption spectra of various C{sub 60}(OH){sub 26} structures in the presence and absence of water molecules, we note that only slight variations in the position and

  10. Protein dynamics: hydration and cavities

    Directory of Open Access Journals (Sweden)

    K. Heremans

    2005-08-01

    Full Text Available The temperature-pressure behavior of proteins seems to be unique among the biological macromolecules. Thermodynamic as well as kinetic data show the typical elliptical stability diagram. This may be extended by assuming that the unfolded state gives rise to volume and enthalpy-driven liquid-liquid transitions. A molecular interpretation follows from the temperature and the pressure dependence of the hydration and cavities. We suggest that positron annihilation spectroscopy can provide additional quantitative evidence for the contributions of cavities to the dynamics of proteins. Only mature amyloid fibrils that form from unfolded proteins are very resistant to pressure treatment.

  11. The Lawn Hill annulus: An Ordovician meteorite impact into water-saturated dolomite

    Science.gov (United States)

    Darlington, Vicki; Blenkinsop, Tom; Dirks, Paul; Salisbury, Jess; Tomkins, Andrew

    2016-12-01

    The Lawn Hill Impact Structure (LHIS) is located 250 km N of Mt Isa in NW Queensland, Australia, and is marked by a highly deformed dolomite annulus with an outer diameter of 18 km, overlying low metamorphic grade siltstone, sandstone, and shale, along the NE margin of the Georgina Basin. This study provides detailed field observations from sections of the Lawn Hill annulus and adjacent areas that demonstrate a clear link between the deformation of the dolomite and the Lawn Hill impact. 40Ar-39Ar dating of impact-related melt particles provides a time of impact in the Ordovician (472 ± 8 Ma) when the Georgina Basin was an active depocenter. The timing and stratigraphic thickness of the dolomite sequence in the annulus suggest that there was possibly up to 300 m of additional sedimentary rocks on top of the currently exposed Thorntonia Limestone at the time of impact. The exposed annulus is remarkably well preserved, with preservation attributed to postimpact sedimentation. The LHIS has an atypical crater morphology with no central uplift. The heterogeneous target materials at Lawn Hill were probably low-strength, porous, and water-saturated, with all three properties affecting the crater morphology. The water-saturated nature of the carbonate unit at the time of impact is thought to have influenced the highly brecciated nature of the annulus, and restricted melt production. The impact timing raises the possibility that the Lawn Hill structure may be a member of a group of impacts resulting from an asteroid breakup that occurred in the mid-Ordovician (470 ± 6 Ma).

  12. Krypton-81 in groundwater of the Culebra Dolomite near the Waste Isolation Pilot Plant, New Mexico.

    Science.gov (United States)

    Sturchio, Neil C; Kuhlman, Kristopher L; Yokochi, Reika; Probst, Peter C; Jiang, Wei; Lu, Zheng-Tian; Mueller, Peter; Yang, Guo-Min

    2014-05-01

    The Waste Isolation Pilot Plant (WIPP) in New Mexico is the first geologic repository for disposal of transuranic nuclear waste from defense-related programs of the US Department of Energy. It is constructed within halite beds of the Permian-age Salado Formation. The Culebra Dolomite, confined within Rustler Formation evaporites overlying the Salado Formation, is a potential pathway for radionuclide transport from the repository to the accessible environment in the human-disturbed repository scenario. Although extensive subsurface characterization and numerical flow modeling of groundwater has been done in the vicinity of the WIPP, few studies have used natural isotopic tracers to validate the flow models and to better understand solute transport at this site. The advent of Atom-Trap Trace Analysis (ATTA) has enabled routine measurement of cosmogenic (81)Kr (half-life 229,000 yr), a near-ideal tracer for long-term groundwater transport. We measured (81)Kr in saline groundwater sampled from two Culebra Dolomite monitoring wells near the WIPP site, and compared (81)Kr model ages with reverse particle-tracking results of well-calibrated flow models. The (81)Kr model ages are ~130,000 and ~330,000 yr for high-transmissivity and low-transmissivity portions of the formation, respectively. Compared with flow model results which indicate a relatively young mean hydraulic age (~32,000 yr), the (81)Kr model ages imply substantial physical attenuation of conservative solutes in the Culebra Dolomite and provide limits on the effective diffusivity of contaminants into the confining aquitards.

  13. A multi-scale assessment of Pb(II) sorption on dolomite.

    Science.gov (United States)

    Lee, Shinwoo; Dyer, James A; Sparks, Donald L; Scrivner, Noel C; Elzinga, Evert J

    2006-06-01

    Macroscopic sorption studies indicated that Pb sorption capacity was independent of pH over the pH range 5-7, while sorption as a function of reaction time up to two weeks for systems with no bulk precipitate phases showed continuous Pb uptake on dolomite. This could be due to diffusion of Pb into the micropores of dolomite as well as an increase in surface sites caused by particle size reduction during suspension mixing. Normalized XANES spectra for systems undersaturated with respect to Pb carbonate precipitates resembled the spectrum of Pb4(OH)4(4+), suggesting that Pb is mainly coordinated to dolomite as an inner-sphere surface complex. On the other hand, the XANES spectrum for 10(-3) M Pb at 1 atm CO2(g) in a 2 M Mg(NO3)2 background electrolyte solution resembled that of cerussite, while a sample at 5 x 10(-4) M Pb in equilibrium with air and 2 M Mg(NO3)2 resembled that of hydrocerussite. EXAFS analyses of sorption samples in chloride solutions showed that there were only first-shell contributions under 1 atm CO2(g), while higher shell contributions from Ca/Mg were seen at 10(-3.42) atm CO2(g). On the other hand, EXAFS samples prepared in nitrate solutions showed noticeable differences in speciation under different reaction conditions-from outer-sphere surface complexes at low Pb concentrations and pH, to inner-sphere surface complexes at moderate Pb concentrations and neutral pH, to the formation of Pb carbonate precipitates at the highest Pb loadings.

  14. Pore Structure Characterization of Indiana Limestone and Pink Dolomite from Pore Network Reconstructions

    Directory of Open Access Journals (Sweden)

    Freire-Gormaly Marina

    2016-05-01

    Full Text Available Carbon sequestration in deep underground saline aquifers holds significant promise for reducing atmospheric carbon dioxide emissions (CO2. However, challenges remain in predicting the long term migration of injected CO2. Addressing these challenges requires an understanding of pore-scale transport of CO2 within existing brine-filled geological reservoirs. Studies on the transport of fluids through geological porous media have predominantly focused on oil-bearing formations such as sandstone. However, few studies have considered pore-scale transport within limestone and other carbonate formations, which are found in potential storage sites. In this work, high-resolution micro-Computed Tomography (microCT was used to obtain pore-scale structural information of two model carbonates: Indiana Limestone and Pink Dolomite. A modified watershed algorithm was applied to extract pore network from the reconstructed microCT volumetric images of rock samples and compile a list of pore-scale characteristics from the extracted networks. These include statistical distributions of pore size and radius, pore-pore separation, throat radius, and network coordination. Finally, invasion percolation algorithms were applied to determine saturation-pressure curves for the rock samples. The statistical distributions were comparable to literature values for the Indiana Limestone. This served as validation for the network extraction approach for Pink Dolomite, which has not been considered previously. Based on the connectivity and the pore-pore separation, formations such as Pink Dolomite may present suitable storage sites for carbon storage. The pore structural distributions and saturation curves obtained in this study can be used to inform core- and reservoir-scale modeling and experimental studies of sequestration feasibility.

  15. Epigenetic dolomitization of the Přaídolí formation (Upper Silurian), the Barrandian basin, Czech Republic: implications for burial history of Lower Paleozoic strata

    Science.gov (United States)

    Suchý, V.; Rozkošný, I.; Žák, K.; Franců, J.

    1996-06-01

    Stratabound epigenetic dolomite occurs in carbonate facies of the Barrandian basin (Silurian and Devonian), Czech Republic. The most intense dolomitization is developed in bioclastic calcarenites within the transition between micritic limestone and shaledominated Přídolí and Lochkov formations deposited on a carbonate slope. Medium-crystalline (100-400 µm), inclusion-rich, xenotopic matrix dolomite ( δ 18O=-4.64 to -3.40‰ PDB; δ 13C=+1.05 to +1.85‰ PDB) which selectively replaced most of the bioclastic precursor is volumetrically the most important dolomite type. Coarse crystalline saddle dolomite ( δ 18O=-8.04 to -5.14‰ PDB; δ 18C=+0.49 to +1.49 PDB) which precipitated in fractures and vugs within the matrix dolomite represents a later diagenetic dolomitization event. In some vugs, saddle dolomite coprecipitated with petroleum inclusion-rich authigenic quartz crystals and minor sulfides which, in turn, were post-dated by semisolid asphaltic bitumen. The interpretation of the dolomitization remains equivocal. Massive xenotopic dolomite, although generally characteristic of a deeper burial setting, may have been formed by a recrystallization of an earlier, possibly shallow burial dolomite. Deeper burial recrystallization by reactive basinal pore fluids that presumably migrated through the more permeable upper portion of the Přídolí sequence appears as a viable explanation for this dolomiti