Sample records for gypsum

  1. Gypsum

    Crangle, R.D.


    The United States is the world’s fifth ranked producer and consumer of gypsum. Production of crude gypsum in the United States during 2012 was estimated to be 9.9 Mt (10.9 million st), an increase of 11 percent compared with 2011 production. The average price of mined crude gypsum was $7/t ($6.35/st). Synthetic gypsum production in 2012, most of which is generated as a flue-gas desulphurization product from coal-fired electric powerplants, was estimated to be 11.8 Mt (13 million st) and priced at approximately $1.50/t ($1.36/st). Forty-seven companies produced gypsum in the United States at 54 mines and plants in 34 states. U.S. gypsum exports totaled 408 kt (450,000 st). Imports were much higher at 3.2 Mt (3.5 million st).

  2. Gypsum karst in Great Britain

    Cooper A.H.


    Full Text Available In Great Britain the most spectacular gypsum karst development is in the Zechstein gypsum (late Permian mainly in north-eastern England. The Midlands of England also has some karst developed in the Triassic gypsum in the vicinity of Nottingham. Along the north-east coast, south of Sunderland, well-developed palaeokarst, with magnificent breccia pipes, was produced by dissolution of Permian gypsum. In north-west England a small gypsum cave system of phreatic origin has been surveyed and recorded. A large actively evolving phreatic gypsum cave system has been postulated beneath the Ripon area on the basis of studies of subsidence and boreholes. The rate of gypsum dissolution here, and the associated collapse lead to difficult civil engineering and construction conditions, which can also be aggravated by water abstraction.

  3. Mechanism of gypsum hydration

    Pacheco, G.


    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.

  4. Polymer composites based on gypsum matrix

    Mucha, Maria; Mróz, Patrycja; Kocemba, Aleksandra [Faculty of Process and Environmental Engineering, Lodz University of Technology, Wólczańska 215 street, 90–924 Łódź (Poland)


    The role of polymers as retarder additives is to prolong the workability connected with setting time of gypsum. Various cellulose derivatives, soluble in water in concentration up to 1,5% by weight were applied taking different water/binder ratio. The hydration process of calcium sulfate hemihydrate (gypsum binder) into dihydrate (gypsum plaster) was observed by setting and calorimetric techniques. Scanning electron microscopy confirmed that the gypsum microstructure was varied when polymers are used. The mechanical properties of gypsum plasters were studied by bending strength test and they are correlated with sample microstructure.

  5. Urban mining : Recycling gypsum waste in Vancouver

    McCamley, J.A. [New West Gypsum Recycling Inc., Vancouver, BC (Canada)


    Wallboard manufacturing, construction and deconstruction activities in North America, Europe and Japan result in large amounts of gypsum scrap, which creates an environmental problem. Disposing of this gypsum scrap in landfills often leads to hydrogen sulfide emissions and metallic sulfide groundwater leachates. Europe has dealt with the problem by enacting legislation that will come into effect in July 2005. The legislation is designed to strongly encourage gypsum recycling throughout entire jurisdictions. It is estimated that approximately 10 to 17 per cent of all gypsum used in the wallboard industry ends up as gypsum scrap. In North America, it represents almost one per cent of total waste. Each year in the United States, between 2.5 and 4.5 million tonnes of gypsum scrap are generated, with numbers very similar to Europe (the higher use of brick and concrete in Europe reduces the percentage of total tonnage). Gypsum has been banned from the landfills of British Columbia's Greater Vancouver region, forcing the recycling of all gypsum scrap. Large quantities of gypsum scrap are processed by New West Recycling, a Canadian firm using proprietary technology. This process leads to the re-incorporation of scrap gypsum into new wallboard, with the percentages sometimes reaching as high as 25 per cent. A case study of New West Recycling Inc., located in Langley, British Columbia was presented and recommendations were made concerning how other urban regions can implement gypsum scrap recycling programs modeled after this one. 6 refs.

  6. Water-resistant gypsum binder

    Panchenko Alexander I.


    Full Text Available The authors developed a multi-component gypsum binder (MGB with an improved (by 1.8 to 2.2 times water resistance value in comparison with the initial gypsum and a softening factor value within the range of 0.85 to 0.91 through the introduction of a complex additive containing carbide mud and bio-silica. The use of a complex additive provides for the formation of a denser structure due to the formation of low-base calcium hydrated silicates at early stages of the hardening process under wet or dry air conditions. The developed binding agent has a lower (by 2.5 to 3 times open porosity, a greater compressive strength (by 1.4 to 1.6 times for a dry state and by 2.6 times in a water-saturated state and does not require any special curing conditions in contrast to the other multi-component gypsum binders. The authors show the influence of mud-and-silica additive on the properties of hardened MGB and suggest a method of computation of the optimum MGB composition for given components.


    Taher Abu-Lebdeh


    Full Text Available The disposal of scrap tires is a challenging task and hence an innovative solution to meet these challenges is needed. Extensive work has been done on the utilization of waste tires in a variety of applications in asphalt pavements and concrete. However, previous investigations focus only on the mechanical properties of the rubberized materials, but few on the thermal performance. This is especially true for rubberized gypsum. Limited or no experimental data on the thermal performance of rubberized gypsum board are available. In this study, an experimental program is established to investigate the effect of amount and size of crumb rubber on the thermal properties of gypsum materials. Gypsum is replaced by four different percentage of crumb rubber: 10, 20, 30 and 40% by weight of gypsum and two sizes of crumb rubber (#30, #10_20 to make eight rubberized gypsum specimens. The prepared specimens were tested for thermal conductivity using an apparatus specially designed and constructed for this purpose. The experimental program was concluded by proposing an empirical equation to predict the thermal conductivity of rubberized gypsum board. Results indicated better thermal performance of the gypsum board due to the addition of crumb rubber. Thermal conductivity of the rubberized gypsum was 18-38% lower than the ordinary gypsum. It is concluded that thermal conductivity of rubberized gypsum decreases with the increase of crumb rubber regardless the size of the rubber and that thermal conductivity of mixtures contained 40% of rubber was about 38% lower than conventional mixture when crumb rubber #10_20 was added, while the thermal conductivity reduced by 22% when crumb rubber #30 was added. The study suggested for future work to investigate the effect of air voids size and ratio on the thermal conductivity of rubberized gypsum.

  8. Cements containing by-product gypsum

    Bensted, J. [University of Greenwich, London (United Kingdom). School of Biological and Chemical Sciences


    Chemical by-product gypsum can readily replace natural gypsum in Portland cements and in blended cements like Portland pfa cement and Portland blast furnace cement without technical detriment in many instances. Indeed, sometimes the technical performance of the cement can be enhanced. The hydration chemistry is often changed, in that where there is at least some retardation of setting, more AFT phase (ettringite) is formed during early hydration at the expense of calcium silicate hydrates. By-product gypsum can also replace natural gypsum in speciality products like calcium aluminate cement-Portland cement mixes for producing quick setting cements and in calcium sulphoaluminate-type expansive cements. However, by-products gypsum have proved to be less successful for utilization in API Classes of oilwell cements, because of the greater difficulty in obtaining batch-to-batch consistency in properties like thickening time and slurry rheology. 11 refs., 3 figs., 5 tabs.

  9. Investigation of the type and content of gypsum on the dimensional stability and mechanical properties of gypsum particleboard

    Hossein Rangavar


    Full Text Available In this study in order to investigate the effect of gypsum type on the physical and mechanical properties of gypsum Particleboard were used from two type Jebel and Micronize gypsum. To obtain the suitable amount of gypsum in manufacturing gypsum particleboard was used from the three levels 2.5:1, 2.75:1 and 3:1 of gypsum to dried mass of wooden materials. Physical and mechanical properties of manufactured board were carried out in accordance with European Norms (EN standard. The result showed that gypsum particleboard manufactured Jebel gypsum have the most mechanical properties (Bending strength, modulus of elasticity and internal bond strength, but physical properties (water absorption and thickness swelling of this boards was more than the boards manufactured from Micronize gypsum. Furthermore using 2.75 times gypsum to dried mass of wooden materials is also suitable in production gypsum particleboard.

  10. Measurement of soil moisture using gypsum blocks

    Friis Dela, B.

    the building. Consequently, measuring the moisture of the surrounding soil is of great importance for detecting the source of moisture in a building. Up till now, information has been needed to carry out individual calibrations for the different types of gypsum blocks available on the market and to account......For the past 50 years, gypsum blocks have been used to determine soil moisture content. This report describes a method for calibrating gypsum blocks for soil moisture measurements. Moisture conditions inside a building are strongly influenced by the moisture conditions in the soil surrounding...

  11. Measurement of soil moisture using gypsum blocks

    Friis Dela, B.

    For the past 50 years, gypsum blocks have been used to determine soil moisture content. This report describes a method for calibrating gypsum blocks for soil moisture measurements. Moisture conditions inside a building are strongly influenced by the moisture conditions in the soil surrounding...... the building. Consequently, measuring the moisture of the surrounding soil is of great importance for detecting the source of moisture in a building. Up till now, information has been needed to carry out individual calibrations for the different types of gypsum blocks available on the market and to account...

  12. Effects of gypsum on trace metals in soils and earthworms

    Mined gypsum has been beneficially used for many years as an agricultural amendment. Currently a large amount of flue gas desulfurization (FGD) gypsum is produced by removal of SO2 from flue gas streams when fuels with high S content are burned. The FGD gypsum, similar to mined gypsum, can enhance c...


    Gypsum wallboard with repeated or prolonged exposure to water or excess moisture can lose its structural integrity and provide a growth medium for biological contaminants. Poorly sealed buildings, leaking or failed plumbing systems, or improperly constructed HVAC systems can all ...


    Anto Gabrić


    Full Text Available The occurences and deposits of gypsum can be found in big karst poljes (Sinjsko, Vrličko, Petrovo, Kosovo and Kninsko as well as in tectonnically predestined river valleys of Zrmanja, Butišnica and Una. There also appear spatially localized occurences on the island of Vis and in the vicinity of Samobor. Evaporites (gypsum and anhydrite with adjoining overlying clastic rocks (red sandstones, siltites and pelites, carbonate rocks (dolomites and limestones and porous carbonate breccias (Rauhwackes were deposited during the period of Upper Permian. The recent position of the Upper Permian beds is a result of complex tectonic, particularly neotectonic, movements and diapiric displacements. Evaporites were deposited in marginal areas of the epicontinental marine basin, in a period of favourable conditions for the sabkha and playa sedimentation due to the continuous shoreline progradation. The Upper Permian age of these sediments in Dalmatio is proved by the characteristic mineral paragenesis and palinological determinations in elastics rocks, as well as by isotope analyses of sulphure in gypsum. Gypsum is a significant ore mineral resource in building, cement production, as well as in a number of tehnological processes used in chemical industry and elsewhere. According to the recent investigations gypsum is predestined to serve as an ore mineral resource of significant perspectives (the paper is published in Croatian.

  15. Gypsum karst in Italy: a review

    De Waele, Jo; Chiarini, Veronica; Columbu, Andrea; D'Angeli, Ilenia M.; Madonia, Giuliana; Parise, Mario; Piccini, Leonardo; Vattano, Marco; Vigna, Bartolomeo; Zini, Luca; Forti, Paolo


    Although outcropping only rarely in Italy, gypsum karst has been described in detail since the early XXth century (Marinelli, 1917). Gypsum caves are now known from almost all Italian regions (Madonia & Forti, 2003), but are mainly localised along the northern border of the Apennine chain (Emilia Romagna and Marche regions), Calabria, and Sicily, where the major outcrops occur. Recently, important caves have also been discovered in the underground gypsum quarries in Piedmont (Vigna et al., 2010). During the late 80s and 90s several multidisciplinary studies have been carried out in many gypsum areas. All this work converged into a comprehensive overview in 2003 (Madonia & Forti, 2003). Further detailed studies focused on the gypsum areas of Emilia Romagna (Chiesi et al., 2010; Forti & Lucci, 2010; Demaria et al., 2012; De Waele & Pasini, 2013; Ercolani et al., 2013; Columbu et al., 2015; Lucci & Piastra, 2015; Tedeschi et al., 2015) and of Sicily (Madonia & Vattano, 2011). Sinkholes related to Permo-Triassic gypsum have been studied in Friuli Venezia Giulia (Zini et al., 2015). This presentation will review the state of the art regarding different aspects of evaporite karst in Italy focusing on the main new results. References Chiesi M., et al. (2010) - Origin and evolution of a salty gypsum/anhydrite karst spring: the case of Poiano (Northern Apennines, Italy). Hydrogeology Journal, 18, pp. 1111-1124. Columbu A. et al. (2015) - Gypsum caves as indicators of climate-driven river incision and aggradation in a rapidly uplifting region. Geology, 43(6), 539-542. Demaria D. et al. (Eds.) (2012), Le Grotte Bolognesi, GSB-USB, 431 p. De Waele J., Pasini G. (2013) - Intra-messinian gypsum palaeokarst in the northern Apennines and its palaeogeographic implications. Terra Nova 25, pp. 199-205. Ercolani M., et al. (Eds.) (2013), I Gessi e la Cave i Monte Tondo. Studio multidisciplinare di un'area carsica nella Vena del Gesso Romagnola. Memorie Ist. It. Spel. II(26), 559 p

  16. Effect of high temperatures on gypsum paste and mortar

    Krejsová, Jitka; Doleželová, Magdalena; Vimmrová, Alena


    This paper describes the influence of high temperatures on some physical and mechanical properties of gypsum mixtures. Two gypsum mixtures were designed, first one was composed of gypsum and citric acid and the second one contained standardized sand also. The samples were exposed to temperatures from 50°C to 1000°C. Results show, that strength changes caused by high temperatures are significant in both mixtures and that the thermal shrinkage is reduced by adding sand to a gypsum mixture.

  17. Mechanical properties of gypsum board at elevated temperatures

    S.M. Cramer; O.M. Friday; R.H. White; G. Sriprutkiat


    Gypsum board is a common fire barrier used in house and general building construction. Recently, evaluation of the collapses of the World Trade Center Towers highlighted the potential role and failure of gypsum board in containing the fires and resisting damage. The use of gypsum board as primary fire protection of light-flame wood or steel construction is ubiquitous....

  18. Dissolution of Gypsum from field observations

    Klimchouk A.


    Full Text Available The paper reports the results of field measurements of gypsum dissolution in various countries (Ukraine, Spain, Italy and others and in different environments (river waters, precipitation, vadose zone, unconfined aquifer, perched cave lakes, ephemeral streams in caves, confined aquifer, cave air.


    Taher Abu-Lebdeh; Ellie Fini; Ashraf Fadiel


    The disposal of scrap tires is a challenging task and hence an innovative solution to meet these challenges is needed. Extensive work has been done on the utilization of waste tires in a variety of applications in asphalt pavements and concrete. However, previous investigations focus only on the mechanical properties of the rubberized materials, but few on the thermal performance. This is especially true for rubberized gypsum. Limited or no experimental data on the thermal performance of rubb...

  20. Tunisian gypsums: Characteristics and use in cement

    Mahmoudi, Salah; Bennour, Ali; Chalwati, Youssef; Souidi, Khouloud; Thabet, Manel; Srasra, Ezzedine; Zargouni, Fouad


    Gypsum materials of hundred meters thickness and interbedded with marine claystones and limestones from different paleogeographic sectors in the Tunisian territory are studied to assess their suitability for cement production. For this reason, thirty representative samples are analysed by chemical, physical and geotechnical tests. The obtained results for the studied gypsum materials are compared to Tunisian and European norms and with the local cements, currently marketed and which obey international norms. Indeed, for all samples hydraulic modulus HM, silica modulus SM and alumina modulus AM vary from (2.37-2.44), (2.48-2.68) and (1.45-2.5), respectively; whereas the required values for these modulus are (1.5-2.5), (2-3) and (1.5-2.5). The same behavior is observed for mineralogical analyses of C3S, C2S, C3A and C4AF and compressive strength at different ages. Briefly, Tunisia contains important reserves of gypsum scattered and spread over the Tunisian territory and can be used for cement production.

  1. Speleothems in gypsum caves and their paleoclimatological significance

    Calaforra, J. M.; Forti, P.; Fernandez-Cortes, A.


    This article highlights the relationship between speleothems growing inside gypsum caves and the particular climate that existed during their development. Speleothems in gypsum caves normally consist of calcium carbonate (calcite) or calcium sulphate (gypsum) and the abundance of such deposits greatly differs from zone to zone. Observations carried out over the last 20 years in gypsum caves subjected to very different climates (Italy, Spain, New Mexico, northern Russia, Cuba, Argentina) highlight wide variation in their cave deposits. In arid or semi-arid climates, the speleothems are mainly composed of gypsum, whilst in temperate, humid or tropical regions, carbonate formations are largely predominant. In polar zones no speleothems develop. These mineralogical details could be useful paleoclimatic indicators of climate change. The interpretation proposed is based on the fact that in gypsum karst the kind of speleothems deposited is determined by competition between the two principal mechanisms that cause precipitation of calcite and gypsum. These mechanisms are completely different: calcite speleothem evolution is mainly controlled by CO2 diffusion, while gypsum deposits develop mostly due to evaporation. Therefore, the prevalence of one kind of speleothem over the other, and the relationship between the solution precipitation processes of calcite and gypsum, may provide evidence of a specific paleoclimate. Additionally, other non-common deposits in gypsum caves like moonmilk, cave rafts and dolomite speleothems can be used as markers for the prevalence of long, dry periods in humid areas, seasonal changes in climate, or rainfall trends in some gypsum areas. Moreover, the dating of gypsum speleothems could contribute paleoclimatic data relating to dry periods when calcite speleothems are not deposited. In contrast, the dating of calcite speleothems in gypsum caves could identify former wet periods in arid zones.


    Mikheenkov Mikhail Arkad'evich


    Full Text Available In the article, the authors consider the feasibility of development of water-hardened gypsum that is capable of hardening in the water. The gypsum in question is made of the gypsum binding material, sulphated Portland cement, and granulated blast-furnace slag. The gypsum developed hereunder has a softening coefficient over 1 while the building gypsum content exceeds 75 %.

  3. Alabaster and Selenite Gypsum:I-Dehydration-Rehydration Comparison Studies


    Two types of gypsum raw materials, selenite and alabaster, were used to prepare dental stone (α-hemihydrate).Gypsum lumps (0.8~2.5 cm) were hydrothermally treated at 135, 160 and 180°C for 6, 2 and 1 h respectively.The physicochemical properties and composition characteristics of the α-hemihydrates prepared from selenite and alabaster raw gypsum were determined. The results indicated that both the selenite and alabaster raw gypsum show the same chemical and mineralogical composition of calcium sulphate dihydrate. They differs only in their microstructure, selenite raw gypsum exhibits perfect regular crystals while alabaster gypsum, on the other hand,exhibits irregular, large size and interlocked crystals. Selenite is more accessible to dehydration than alabaster raw gypsum. The α-hemihydrate samples prepared from alabaster raw gypsum showed a very short setting time and a lower compressive strength values in relation to that prepared from selenite gypsum. The compressive strength values of the all prepared samples were higher than that specified by A.D.A specification for dental use. To optimize the setting time of both products further studies are needed.

  4. Use of waste gypsum to replace natural gypsum as set retarders in portland cement.

    Chandara, Chea; Azizli, Khairun Azizi Mohd; Ahmad, Zainal Arifin; Sakai, Etsuo


    The present study is focused on clarifying the influence of waste gypsum (WG) in replacing natural gypsum (NG) in the production of ordinary Portland cement (OPC). WG taken from slip casting moulds in a ceramic factory was formed from the hydration of plaster of paris. Clinker and 3-5wt% of WG was ground in a laboratory ball mill to produce cement waste gypsum (CMWG). The same procedure was repeated with NG to substitute WG to prepare cement natural gypsum (CMNG). The properties of NG and WG were investigated via X-ray Diffraction (XRD), X-ray fluorescence (XRF) and differential scanning calorimetry (DSC)/thermogravimetric (TG) to evaluate the properties of CMNG and CMWG. The mechanical properties of cement were tested in terms of setting time, flexural and compressive strength. The XRD result of NG revealed the presence of dihydrate while WG contained dihydrate and hemihydrate. The content of dihydrate and hemihydrates were obtained via DSC/TG, and the results showed that WG and NG contained 12.45% and 1.61% of hemihydrate, respectively. Furthermore, CMWG was found to set faster than CMNG, an average of 15.29% and 13.67% faster for the initial and final setting times, respectively. This was due to the presence of hemihydrate in WG. However, the values obtained for flexural and compressive strength were relatively the same for CMNG and CMWG. Therefore, this result provides evidence that WG can be used as an alternative material to NG in the production of OPC.

  5. Physical, mechanical, and durability properties of gypsum-Portland cement-natural pozzolan blends

    Colak A


    This paper deals with the effect of gypsum Portland cement and gypsum Portland cement natural pozzolan ratios on the physical, mechanical, and durability properties of gypsum Portland cement natural pozzolan blends...

  6. Health survey in gypsum mines in India

    Nandi Subroto


    Full Text Available Background: Mining is a hazardous occupation in which workers are exposed to adverse conditions. In India, gypsum mining is mainly carried out in the state of Rajasthan, which contributes about 99% of the total production. Objective: The present study was carried out in 12 different gypsum mines in Rajasthan state to determine the health status of the miners. Materials and Methods: One hundred and fifty workers engaged in mining activities were included in the study and their health status was compared with that of 83 office staff of the same mines. The health status of the employees was evaluated using a standardized medical questionnaire and pulmonary function testing. Statistical Analysis: The unpaired ′t′ test was used to determine whether there was any significant difference between the miners and the controls and the chi-square test to compare the prevalences of various respiratory impairments in workers with that in controls; we also examined the differences between smokers and nonsmokers. Results: Our findings show that the literacy rate is low (42% among the miners. Pulmonary restrictive impairment was significantly higher amongst smokers as compared to nonsmokers in both miners and controls. Hypertension (22.6%, diabetes (8.8%, and musculoskeletal morbidity (8% were the common diseases in miners. Conclusion: This study shows that there is high morbidity amongst miners, thus indicating the need for regular health checkups, health education, use of personal protective devices, and engineering measures for control of the workplace environment.

  7. Geology of the Gypsum Gap quadrangle, Colorado

    Cater, Fred W.


    The Gypsum Gap quadrangle is one eighteen 7 1/2-minute quadrangles covering the principal carnotite-producing area of southwestern Colorado. The geology of these quadrangles was mapped by the U.S. Geological Survey for the Atomic Energy Commission as part of a comparative study of carnotite deposits. The rocks exposed in the eighteen quadrangles consist of crystalline rocks of pre-Cambrian age and sedimentary rocks that range in age from late Paleozoic to Quaternary. Over much of the area the sedimentary rocks are flat lying, but in places the rocks are disrupted by high-angle faults, and northwest-trending folds. Conspicuous among the folds are large anticlines having cores of intrusive salt and gypsum. Most of the carnotite deposits are confined to the Salt Wash sandstone member of the Jurassic Morrison formation. Within this sandstone, most of the deposits are spottily distributed through a arcuate zone known as the "Uravan Mineral Belt". Individual deposits range in size from irregular masses containing only a few tons of ore to large, tabular masses containing many thousands of tons. The core consists largely of sandstone selectively impregnated and in part replaced by uranium and vanadium minerals. Most of the deposits appear to be related to certain sedimentary structures in sandstones of favorable composition.

  8. Flue gas desulfurization gypsum and fly ash


    The Cumberland Fossil Plant (CUF) is located in Stewart County, Tennessee, and began commercial operation in 1972. This is the Tennessee Valley Authority`s newest fossil (coal-burning) steam electric generating plant. Under current operating conditions, the plant burns approximately seven million tons of coal annually. By-products from the combustion of coal are fly ash, approximately 428,000 tons annually, and bottom ash, approximately 115,000 tons annually. Based on historical load and projected ash production rates, a study was initially undertaken to identify feasible alternatives for marketing, utilization and disposal of ash by-products. The preferred alternative to ensure that facilities are planned for all by-products which will potentially be generated at CUF is to plan facilities to handle wet FGD gypsum and dry fly ash. A number of different sites were evaluated for their suitability for development as FGD gypsum and ash storage facilities. LAW Engineering was contracted to conduct onsite explorations of sites to develop information on the general mature of subsurface soil, rock and groundwater conditions in the site areas. Surveys were also conducted on each site to assess the presence of endangered and threatened species, wetlands and floodplains, archaeological and cultural resources, prime farmland and other site characteristics which must be considered from an environmental perspective.

  9. Raman spectroscopy of shocked gypsum from a meteorite impact crater

    Brolly, Connor; Parnell, John; Bowden, Stephen


    Impact craters and associated hydrothermal systems are regarded as sites within which life could originate on Earth, and on Mars. The Haughton impact crater, one of the most well preserved craters on Earth, is abundant in Ca-sulphates. Selenite, a transparent form of gypsum, has been colonized by viable cyanobacteria. Basement rocks, which have been shocked, are more abundant in endolithic organisms, when compared with un-shocked basement. We infer that selenitic and shocked gypsum are more suitable for microbial colonization and have enhanced habitability. This is analogous to many Martian craters, such as Gale Crater, which has sulphate deposits in a central layered mound, thought to be formed by post-impact hydrothermal springs. In preparation for the 2020 ExoMars mission, experiments were conducted to determine whether Raman spectroscopy can distinguish between gypsum with different degrees of habitability. Ca-sulphates were analysed using Raman spectroscopy and results show no significant statistical difference between gypsum that has experienced shock by meteorite impact and gypsum, which has been dissolved and re-precipitated as an evaporitic crust. Raman spectroscopy is able to distinguish between selenite and unaltered gypsum. This shows that Raman spectroscopy can identify more habitable forms of gypsum, and demonstrates the current capabilities of Raman spectroscopy for the interpretation of gypsum habitability.

  10. Hydrogen sulfide release from dairy manure storages containing gypsum bedding

    Recycled gypsum products can provide a cost-effective bedding alternative for dairy producers. Manufacturers report reduced odors, moisture and bacteria in the stall environment when compared to traditional bedding. Gypsum provides a sulfate source that can be converted to hydrogen sulfide under ana...

  11. Modification of FGD gypsum in hydrothermal mixed salt solution

    WU Xiao-qin; WU Zhong-biao


    A novel utilization way of the sludge from wet calcium-based flue gas desulfurization (FGD) processes has been developed in this paper. This study focused on the conversion of the FGD gypsum into α-hemihydrate calcium sulfate by a hydrothermal salt solution method at atmospheric pressure. Experimental study has been carried out in a batch reactor. Qualitative and quantitative analyses were made by DSC/TG thermal analysis, SEM, XRD, metalloscope and chemical analysis. The experimental results showed that the modification of FGD gypsum was controlled by the dissolution and recrystallization mechanisms. With the introduction of FGD gypsum the salt solution was supersaturated, then crystal nucleus of α-hemihydrate calcium sulfate were produced in the solution. With the submicroscopic structure of FGD gypsum crystal changed, the crystal nucleus grew up into α-hemihydrate calcium sulfate crystals. Thus, the modification of FGD gypsum was fulfilled.

  12. Effect of background electrolytes on gypsum dissolution

    Burgos-Cara, Alejandro; Putnis, Christine; Ruiz-Agudo, Encarnacion


    Knowledge of the dissolution behaviour of gypsum (CaSO4· 2H2O) in aqueous solutions is of primary importance in many natural and technological processes (Pachon-Rodriguez and Colombani, 2007), including the weathering of rocks and gypsum karst formations, deformation of gypsum-bearing rocks, the quality of drinking water, amelioration of soil acidity, scale formation in the oil and gas industry or measurement of water motion in oceanography. Specific ions in aqueous solutions can play important but very different roles on mineral dissolution. For example, the dissolution rates and the morphology of dissolution features may be considerably modified by the presence of the foreign ions in the solution, which adsorb at the surface and hinder the detachment of the ions building the crystal. Dissolution processes in the aqueous environment are closely related to the rearrangement of water molecules around solute ions and the interaction between the solvent molecules themselves. The rearrangement of water molecules with respect to solute species has been recognized as the main kinetic barrier for crystal dissolution in many systems (Davis, 2000; De Yoreo and Dove 2004; Wasylenki et al. 2005). Current research suggest that the control that electrolytes exert on water structure is limited to the local environment surrounding the ions and is not related to long-range electric fields emanating from the ions but results from effects associated with the hydration shell(s) of the ions (Collins et al. 2007) and the ions' capacity to break or structure water (i.e. chaotropic and kosmotropic ions, respectively). These effects will ultimately affect the kinetics of crystal dissolution, and could be correlated with the water affinity of the respective background ions following a trend known as the lyotropic or Hofmeister series (Kunz et al. 2004; Dove and Craven, 2005). In situ macroscopic and Atomic Force Microscopy (AFM) flow-through dissolution experiments were conducted at a

  13. Water defluoridation using Malawi’s locally sourced gypsum

    Masamba, W. R. L.; Sajidu, S. M.; Thole, B.; Mwatseteza, J. F.

    Free fluoride levels above the WHO guideline maximum value of 1.5 mg/l have been reported in several parts of Malawi. Dental fluorosis has also been observed in the same areas such that search for local defluoridation techniques has become important in the country. The present research intended to determine the potential of using Malawi gypsum in defluoridation, identify the best pre-treatment of the gypsum and optimum conditions under which effective water defluoridation with the gypsum may be obtained. Laboratory experiments were carried out to explore defluoridation of drinking water using locally sourced gypsum and gypsum calcined at high temperatures. A 400 °C calcined phase of gypsum gave the highest defluoridation capacity of 67.80% compared to raw (uncalcined) gypsum, 200, 300 and 500 °C calcined phases. Powder X-ray diffraction (PXRD) pattern of the 400 °C phase revealed existence of less crystalline CaSO 4 that was thought to be responsible for such relatively high defluoridation capacity. The dependence of the fluoride removal by the 400 °C calcined phase on other drinking water quality parameters was assessed by simple correlation analysis. Reaction kinetics and mechanisms of fluoride removal by the materials were also investigated. It was found that ion exchange was the dominant mechanism through which fluoride was removed from water by the materials.

  14. Sustainable Uses of FGD Gypsum in Agricultural Systems: Introduction.

    Watts, Dexter B; Dick, Warren A


    Interest in using gypsum as a management tool to improve crop yields and soil and water quality has recently increased. Abundant supply and availability of flue gas desulfurization (FGD) gypsum, a by-product of scrubbing sulfur from combustion gases at coal-fired power plants, in major agricultural producing regions within the last two decades has attributed to this interest. Currently, published data on the long-term sustainability of FGD gypsum use in agricultural systems is limited. This has led to organization of the American Society of Agronomy's Community "By-product Gypsum Uses in Agriculture" and a special collection of nine technical research articles on various issues related to FGD gypsum uses in agricultural systems. A brief review of FGD gypsum, rationale for the special collection, overviews of articles, knowledge gaps, and future research directions are presented in this introductory paper. The nine articles are focused in three general areas: (i) mercury and other trace element impacts, (ii) water quality impacts, and (iii) agronomic responses and soil physical changes. While this is not an exhaustive review of the topic, results indicate that FGD gypsum use in sustainable agricultural production systems is promising. The environmental impacts of FGD gypsum are mostly positive, with only a few negative results observed, even when applied at rates representing cumulative 80-year applications. Thus, FGD gypsum, if properly managed, seems to represent an important potential input into agricultural systems. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  15. Alfalfa Responses to Gypsum Application Measured Using Undisturbed Soil Columns

    Rebecca Tirado-Corbalá


    Full Text Available Gypsum is an excellent source of Ca and S, both of which are required for crop growth. Large amounts of by-product gypsum [Flue gas desulfurization gypsum-(FGDG] are produced from coal combustion in the United States, but only 4% is used for agricultural purposes. The objective of this study was to evaluate the effects of (1 untreated, (2 short-term (4-year annual applications of gypsum totaling 6720 kg ha−1, and (3 long-term (12-year annual applications of gypsum totaling 20,200 kg ha−1 on alfalfa (Medicago sativa L. growth and nutrient uptake, and gypsum movement through soil. The study was conducted in a greenhouse using undisturbed soil columns of two non-sodic soils (Celina silt loam and Brookston loam. Aboveground growth of alfalfa was not affected by gypsum treatments when compared with untreated (p > 0.05. Total root biomass (0–75 cm for both soils series was significantly increased by gypsum application (p = 0.04, however, increased root growth was restricted to 0–10 cm depth. Soil and plant analyses indicated no unfavorable environmental impact from of the 4-year and 12-year annual application of FGDG. We concluded that under sufficient water supply, by-product gypsum is a viable source of Ca and S for land application that might benefit alfalfa root growth, but has less effect on aboveground alfalfa biomass production. Undisturbed soil columns were a useful adaptation of the lysimeter method that allowed detailed measurements of alfalfa nutrient uptake, root biomass, and yield and nutrient movement in soil.

  16. Gypsum crystals in the inner shelf sediments off Maharashtra, India

    Hashimi, N.H.; Ambre, N.V.

    Gypsum crystals have been found in the inner shelf silty clay/clayey silt off the Maharashtra Coast between Vengurla and Bombay. Generally these occur as euhedral single or twinned crystals of selenite. Very often shells are found embedded within...


    Ustinova Yuliya Valer'evna; Sivkov Sergey Pavlovich; Barinova Ol'ga Pavlovna; Sanzharovskiy Aleksandr Yur'evich


    Nowadays, functional additives represented by multiple classes of substances and compounds, including polymers of different origin, are available for introduction into dry mixtures based on gypsum binders. However, their impact onto the growth and formation of calcium sulfate dihydrate (CaSO∙2HO) crystals generated in the course of hardening of gypsum binders is not quite clear. Therefore, the objective of the research was to analyze the processes of growth and formation of calcium sulfate di...

  18. Interaction of gypsum with lead in aqueous solutions

    Astilleros, J.M., E-mail: [Dpto. Cristalografia y Mineralogia, Universidad Complutense de Madrid, Jose Antonio Novais, 2, E-28040 Madrid (Spain); Godelitsas, A. [Department of Mineralogy and Petrology, Faculty of Geology and Geoenvironment, University of Athens, Panepistimioupoli Zographou, 15784 Athens (Greece); Rodriguez-Blanco, J.D. [School of Earth and Environments, Faculty of Environment, University of Leeds, Leeds LS2 9JT (United Kingdom); Fernandez-Diaz, L. [Dpto. Cristalografia y Mineralogia, Universidad Complutense de Madrid, Jose Antonio Novais, 2, E-28040 Madrid (Spain); Prieto, M. [Dpto. de Geologia, Universidad de Oviedo, E-30005 Oviedo (Spain); Lagoyannis, A.; Harissopulos, S. [Tandem Accelerator Laboratory, Institute of Nuclear Physics, NCSR ' Demokritos' , GR-15310 Attiki (Greece)


    Sorption processes on mineral surfaces are a critical factor in controlling the distribution and accumulation of potentially harmful metals in the environment. This work investigates the effectiveness of gypsum (CaSO{sub 4}.2H{sub 2}O) to sequester Pb. The interaction of gypsum fragments with Pb-bearing solutions (10, 100 and 1000 mg/L) was monitored by performing macroscopic batch-type experiments conducted at room temperature. The aqueous phase composition was periodically determined by Atomic Absorption Spectrometry (AAS), Ion Chromatography (IC) and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Regardless of the [Pb{sub aq}]{sub initial}, a [Pb{sub aq}]{sub final} < 4 mg/L was always reached. The uptake process was fast (t < 1 h) for [Pb{sub aq}]{sub initial} {>=} 100 mg/L and significantly slower (t > 1 week) for [Pb{sub aq}]{sub initial} = 10 mg/L. Speciation calculations revealed that after a long time of interaction (1 month), all the solutions reached equilibrium with respect to both gypsum and anglesite. For [Pb{sub aq}]{sub initial} {>=} 100 mg/L, sorption takes place mainly via the rapid dissolution of gypsum and the simultaneous formation of anglesite both on the gypsum surface and in the bulk solution. In the case of [Pb{sub aq}]{sub initial} = 10 mg/L, no anglesite precipitation was observed, but surface spectroscopy (proton Rutherford Backscattering Spectroscopy, p-RBS) confirmed the formation of Pb-bearing surface layers on the (0 1 0) gypsum surface in this case also. This study shows that the surface of gypsum can play an important role in the attenuation of Pb in contaminated waters.

  19. Unravelling the mechanisms for plant survival on gypsum soils: an analysis of the chemical composition of gypsum plants from Turkey.

    Bolukbasi, A; Kurt, L; Palacio, S


    Depending on their specificity to gypsum, plants can be classified as gypsophiles (gypsum exclusive) and gypsovags (non-exclusive). The former may further be segregated into wide and narrow gypsophiles, depending on the breadth of their distribution area. Narrow gypsum endemics have a putative similar chemical composition to plants non-exclusive to gypsum (i.e. gypsovags), which may indicate their similar ecological strategy as stress-tolerant plant refugees on gypsum. However, this hypothesis awaits testing in different regions of the world. We compared the chemical composition of four narrow gypsum endemics, one widely distributed gypsophile and six gypsovags from Turkey. Further, we explored the plasticity in chemical composition of Turkish gypsovags growing on high- and low-gypsum content soils. Differences were explored with multivariate analyses (RDA) and mixed models (REML). Narrow gypsum endemics segregated from gypsovags in their chemical composition according to RDAs (mainly due to higher K and ash content in the former). Nevertheless, differences were small and disappeared when different nutrients were analysed individually. All the gypsovags studied accumulated more S and ash when growing on high-gypsum than on low-gypsum soils. Similar to narrow gypsum endemics from other regions of the world, most local gypsum endemics from Turkey show a similar chemical composition to gypsovags. This may indicate a shared ecological strategy as stress-tolerant plants not specifically adapted to gypsum. Nevertheless, the narrow gypsum endemic Gypsophila parva showed a chemical composition typical of gypsum specialists, indicating that various strategies are feasible within narrowly distributed gypsophiles. © 2015 German Botanical Society and The Royal Botanical Society of the Netherlands.

  20. Fate of Mercury in Synthetic Gypsum Used for Wallboard Production

    Jessica Marshall Sanderson


    This report presents and discusses results from Task 5 of the study ''Fate of Mercury in Synthetic Gypsum Used for Wallboard Production,'' performed at a full-scale commercial wallboard plant. Synthetic gypsum produced by wet flue gas desulfurization (FGD) systems on coal-fired power plants is commonly used in the manufacture of wallboard. The FGD process is used to control the sulfur dioxide emissions which would result in acid rain if not controlled. This practice has long benefited the environment by recycling the FGD gypsum byproduct, which is becoming available in increasing quantities, decreasing the need to landfill this material, and increasing the sustainable design of the wallboard product. However, new concerns have arisen as recent mercury control strategies developed for power plants involve the capture of mercury in FGD systems. The objective of this study is to determine whether any mercury is released into the atmosphere when the synthetic gypsum material is used as a feedstock for wallboard production. The project is being co-funded by the U.S. DOE National Energy Technology Laboratory (Cooperative Agreement DE-FC26-04NT42080), USG Corporation, and EPRI. USG Corporation is the prime contractor, and URS Group is a subcontractor. The project scope includes five discrete tasks, each conducted at various USG wallboard plants using synthetic gypsum from different FGD systems. The five tasks were to include (1) a baseline test, then variations representing differing power plant (2) emissions control configurations, (3) treatment of fine gypsum particles, (4) coal types, and (5) FGD reagent types. However, Task 5, which was to evaluate gypsum produced from an alternate FGD reagent, could not be conducted as planned. Instead, Task 5 was conducted at conditions similar to a previous task, Task 3, although with gypsum from an alternate FGD system. In this project, process stacks in the wallboard plant have been sampled using the Ontario

  1. Fate of Mercury in Synthetic Gypsum Used for Wallboard Production

    Jessica Sanderson


    This report presents and discusses results from the project 'Fate of Mercury in Synthetic Gypsum Used for Wallboard Production', performed at five different full-scale commercial wallboard plants. Synthetic gypsum produced by wet flue gas desulfurization (FGD) systems on coal-fired power plants is commonly used in the manufacture of wallboard. This practice has long benefited the environment by recycling the FGD gypsum byproduct, which is becoming available in increasing quantities, decreasing the need to landfill this material, and increasing the sustainable design of the wallboard product. However, new concerns have arisen as recent mercury control strategies involve the capture of mercury in FGD systems. The objective of this study has been to determine whether any mercury is released into the atmosphere at wallboard manufacturing plants when the synthetic gypsum material is used as a feedstock for wallboard production. The project has been co-funded by the U.S. DOE National Energy Technology Laboratory (Cooperative Agreement DE-FC26-04NT42080), USG Corporation, and EPRI. USG Corporation is the prime contractor, and URS Group is a subcontractor. The project scope included seven discrete tasks, each including a test conducted at various USG wallboard plants using synthetic gypsum from different wet FGD systems. The project was originally composed of five tasks, which were to include (1) a base-case test, then variations representing differing power plant: (2) emissions control configurations, (3) treatment of fine gypsum particles, (4) coal types, and (5) FGD reagent types. However, Task 5,could not be conducted as planned and instead was conducted at conditions similar to Task 3. Subsequently an opportunity arose to test gypsum produced from the Task 5 FGD system, but with an additive expected to impact the stability of mercury, so Task 6 was added to the project. Finally, Task 7 was added to evaluate synthetic gypsum produced at a power plant from an

  2. Synthesis on research results of FGD gypsum briquetting

    Kosturkiewicz Bogdan


    Full Text Available FGD gypsum products can be characterized by significant solubility in water and dusting in dry state. These characteristics can cause a considerable pollution of air, water and soil. Among many approaches of preparing utilization of this waste, the process of compaction using briquetting has proved to be very effective. Using FGD gypsum products a new material of fertilizers characteristics has been acquired and this material is resistant to the conditions of transportation. This paper presents results of experimental briquetting of flue gas desulphurisation products in a roll press. The experiments were conducted in a laboratory roll presses LPW 450 and LPW 1100 equipped with two interchangeable forming rings that form material into saddle-shaped briquettes with volume 6,5 cm3 and 85 cm3. The experiments were conducted with various percentage amounts of FGD gypsum moisture. The results provided information regarding influence of moisture and roll press configuration on quality of briquettes. On the basis of obtained results, technological process and a general outline of technological line for FGD gypsum were developed. Two roll presses of own construction with different outputs were identified as appropriate for this purpose. A range of necessary works related to their adaptation for the FGD gypsum briquetting were pointed out.

  3. Converting SDAP into gypsum in a wet limestone scrubber

    Fogh, F. [Faelleskemikerne, Elsamprojekt A/S, Fredericia (Denmark)


    The ELSAM power pool has an installed electrical capacity of approx. 5 GW{sub e}, mainly firing import coal. The major base load units are equipped with desulphurization units and three different desulphurization technologies are used: the wet limestone gypsum process, the spray dry absorption process and a sulphuric acid process. Gypsum and sulphuric acid are commercialized, whereas it has been difficult to utilize the spray dry absorption product (SDAP). The main constituents of SDAP are calcium sulphide, calcium chloride, hydrated lime and impurities mainly originating from fly ash. Sulphide can be oxidized into sulphate in acidic solution - the reaction is utilized in the wet limestone gypsum process - and the possibility of using any spare capacity in the wet limestone gypsum units to oxidize the sulphide content of SDAP into sulphate and produce usable gypsum has been investigated in the laboratory and in a 400 MW{sub e} equivalent wet limestone unit. The limestone inhibition effect of the addition of SDAP is currently being studied in the laboratory in order to determine the effect of different SDAP types (plant/coal sources) on limestone reactivity before further long-term full-scale tests are performed and permanent use of the process planned. (EG)

  4. Using stable isotopes (δ^{18}O and δ$D) of gypsum hydration water to unravel the mode of gypsum speleothem formation in semi-arid caves

    Gázquez, Fernando; Calaforra, Jose Maria; Evans, Nicholas P.; Hodell, David A.


    Subaerial gypsum speleothems form during the evaporation of calcium-sulfate-rich solutions in caves. The evaporation of infiltration water is the widely accepted mechanism to explain precipitation of gypsum speleothems; i.e., the dissolution of gypsum host-rock (e.g. Messinian marine gypsum) supplies Ca2+ and SO42- ions to cave waters and subsequent evaporation leads to gypsum saturation. However, water condensation actively occurs in caves of semi-arid regions and plays a key role in subaerial cave speleogenesis and recharge of aquifers in low-rainfall environments. To date, water condensation in karstic environments has not been considered as an important factor in gypsum speleothem formation. We collected speleothem samples from the upper passages of Covadura Cave in the gypsum karst of Sorbas (Almeria, SE Spain). This cave is located in a temperate (annual mean temperature of 19.5oC), semi-arid region (

  5. Calcium isotopic fractionation in microbially mediated gypsum precipitates

    Harouaka, Khadouja; Mansor, Muammar; Macalady, Jennifer L.; Fantle, Matthew S.


    Gypsum (CaSO4·2H2O) precipitation experiments were carried out at low pH in the presence of the sulfur oxidizing bacterium Acidithiobacillus thiooxidans. The observed Ca isotopic fractionation (expressed as Δ44/40Cas-f = δ44/40Casolid-δ44/40Cafluid) at the end of each experimental time period (∼50 to 60 days) was -1.41‰ to -1.09‰ in the biotic experiments, -1.09‰ in the killed control, and -1.01‰ to -0.88‰ in the abiotic controls. As there were no strong differences in the solution chemistry and the rate at which gypsum precipitated in the biotic and abiotic controls, we deduce a biological Ca isotope effect on the order of -0.3‰. The isotope effect correlates with a difference in crystal aspect ratios between the biotic experiments (8.05 ± 3.99) and abiotic controls (31.9 ± 8.40). We hypothesize that soluble and/or insoluble organic compounds selectively inhibit crystal growth at specific crystal faces, and that the growth inhibition affects the fractionation factor associated with gypsum precipitation. The experimental results help explain Ca isotopic variability in gypsum sampled from a sulfidic cave system, in which gypsum crystals exhibiting a diversity of morphologies (microcrystalline to cm-scale needles) have a broad range of δ44/40Ca values (∼1.2-0.4‰) relative to the limestone wall (δ44/40Ca = 1.3‰). In light of the laboratory experiments, the variation in Ca isotope values in the caves can be interpreted as a consequence of gypsum precipitation in the presence of microbial organic matter and subsequent isotopic re-equilibration with the Ca source.

  6. Gypsum scaling in pressure retarded osmosis: experiments, mechanisms and implications.

    Zhang, Minmin; Hou, Dianxun; She, Qianhong; Tang, Chuyang Y


    Pressure retarded osmosis (PRO) is an osmotically-driven membrane process that can be used to harvest salinity-gradient power. The PRO performance (both water flux and power density) can be severely limited by membrane fouling. The current study, for the first time, investigates PRO scaling in a bench-scale pressurized system using calcium sulfate dihydrate (gypsum) as a model scalant. In addition to the bulk feed solution (FS) saturation index (SI bulk), gypsum scaling was found to be strongly affected by the draw solution (DS) type and concentration, the applied hydraulic pressure, and the membrane orientation. The commonly recommended active layer facing draw solution (AL-DS) orientation was highly prone to internal scaling. In this orientation, severe internal concentration polarization (ICP) of scaling precursors induced gypsum clogging in membrane support layer even when the FS was undersaturated (e.g., SI bulk = 0.8). At higher SI bulk values, external gypsum crystal deposition occurred in addition to internal scaling. More severe scaling was observed when the DS contained scaling precursors such as Ca(2+) or SO4(2-), suggesting that the reverse diffusion of these precursors into the FS can significantly enhanced gypsum scaling. Increasing applied hydraulic pressure could enhance reverse solute diffusion and thus result in more severe gypsum scaling when the DS contained scaling precursors. A conceptual model, capturing the two important PRO scaling mechanisms (ICP of scaling precursors from FS and reverse diffusion of scaling precursors from the DS), is presented to rationalize the experimental results. Our results provide significant implications for PRO scaling control.

  7. Triple oxygen isotope systematics of structurally bonded water in gypsum

    Herwartz, Daniel; Surma, Jakub; Voigt, Claudia; Assonov, Sergey; Staubwasser, Michael


    The triple oxygen isotopic composition of gypsum mother water (gmw) is recorded in structurally bonded water in gypsum (gsbw). Respective fractionation factors have been determined experimentally for 18O/16O and 17O/16O. By taking previous experiments into account we suggest using 18αgsbw-gmw = 1.0037; 17αgsbw-gmw = 1.00195 and θgsbw-gmw = 0.5285 as fractionation factors in triple oxygen isotope space. Recent gypsum was sampled from a series of 10 ponds located in the Salar de Llamara in the Atacama Desert, Chile. Total dissolved solids (TDS) in these ponds show a gradual increase from 23 g/l to 182 g/l that is accompanied by an increase in pond water 18O/16O. Gsbw falls on a parallel curve to the ambient water from the saline ponds. The offset is mainly due to the equilibrium fractionation between gsbw and gmw. However, gsbw represents a time integrated signal biased towards times of strong evaporation, hence the estimated gmw comprises elevated 18O/16O compositions when compared to pond water samples taken on site. Gypsum precipitation is associated with algae mats in the ponds with lower salinity. No evidence for respective vital effects on the triple oxygen isotopic composition of gypsum hydration water is observed, nor are such effects expected. In principle, the array of δ18Ogsbw vs. 17Oexcess can be used to: (1) provide information on the degree of evaporation during gypsum formation; (2) estimate pristine meteoric water compositions; and (3) estimate local relative humidity which is the controlling parameter of the slope of the array for simple hydrological situations. In our case study, local mining activities may have decreased deep groundwater recharge, causing a recent change of the local hydrology.

  8. Fate of Mercury in Synthetic Gypsum Used for Wallboard Production

    Jessica Sanderson; Gary M. Blythe; Mandi Richardson


    This report presents and discusses results from Task 6 of the study 'Fate of Mercury in Synthetic Gypsum Used for Wallboard Production,' performed at a full-scale commercial wallboard plant. Synthetic gypsum produced by wet flue gas desulfurization (FGD) systems on coal-fired power plants is commonly used in the manufacture of wallboard. This practice has long benefited the environment by recycling the FGD gypsum byproduct, which is becoming available in increasing quantities, decreasing the need to landfill this material, and increasing the sustainable design of the wallboard product. However, new concerns have arisen as recent mercury control strategies involve the capture of mercury in FGD systems. The objective of this study is to determine whether any mercury is released into the atmosphere when the synthetic gypsum material is used as a feedstock for wallboard production. The project is being co-funded by the U.S. DOE National Energy Technology Laboratory (Cooperative Agreement DE-FC26-04NT42080), USG Corporation, and EPRI. USG Corporation is the prime contractor, and URS Group is a subcontractor. The project scope now includes six discrete tasks, each conducted at various USG wallboard plants using synthetic gypsum from different FGD systems. The project was originally composed of five tasks, which were to include (1) a baseline test, then variations representing differing power plant: (2) emissions control configurations, (3) treatment of fine gypsum particles, (4) coal types, and (5) FGD reagent types. However, Task 5, which was to include testing with an alternate FGD reagent, could not be conducted as planned. Instead, Task 5 was conducted at conditions similar to Task 3, although with gypsum from an alternate FGD system. Subsequent to conducting Task 5 under these revised conditions, an opportunity arose to test gypsum produced at the same FGD system, but with an additive (Degussa Corporation's TMT-15) being used in the FGD system. TMT-15

  9. Physicochemical Properties and Cellular Responses of Strontium-Doped Gypsum Biomaterials

    Amir Pouria


    Full Text Available This paper describes some physical, structural, and biological properties of gypsum bioceramics doped with various amounts of strontium ions (0.19–2.23 wt% and compares these properties with those of a pure gypsum as control. Strontium-doped gypsum (gypsum:Sr was obtained by mixing calcium sulfate hemihydrate powder and solutions of strontium nitrate followed by washing the specimens with distilled water to remove residual salts. Gypsum was the only phase found in the composition of both pure and gypsum:Sr, meanwhile a shift into lower diffraction angles was observed in the X-ray diffraction patterns of doped specimens. Microstructure of all gypsum specimens consisted of many rod-like small crystals entangled to each other with more elongation and higher thickness in the case of gypsum:Sr. The Sr-doped sample exhibited higher compressive strength and lower solubility than pure gypsum. A continuous release of strontium ions was observed from the gypsum:Sr during soaking it in simulated body fluid for 14 days. Compared to pure gypsum, the osteoblasts cultured on strontium-doped samples showed better proliferation rate and higher alkaline phosphatase activity, depending on Sr concentration. These observations can predict better in vivo behavior of strontium-doped gypsum compared to pure one.

  10. Suitability of coarse-grade gypsum for sodic soil reclamation: a laboratory experiment

    Elshout, van den S.; Kamphorst, A.


    Costs of sodic soil reclamation can be reduced when coarse-grade gypsum is used, as the production and transport prices of this gypsum are much lower than that of agricultural-grade gypsum. In a feasibility study laboratory experiments were conducted to evaluate the leaching water requirements for f

  11. Evaluation of gypsum rates on greenhouse crop production

    This study was to determine the potential of an added value distribution channel for gypsum waste by evaluating various greenhouse crops with captious pH and calcium needs. Three studies consisting of: Zonal geranium (Pelargonium x hortorum) and petunia (Petunia x hybrida); tomato (Solanum lycoper...

  12. The Gypsum: White gold of Rajasthan, introduction, uses and future prospective

    Sharma, Gayatri


    Rajasthan is mineral based state and Bikaner and its surrounding district have been gifted with Gypsum. Mt of Gypsum is available in these districts. Gypsum has multiple uses including basic raw material for POP industry, addition in cement and a natural fertilizer. This mineral has changes the economic scenario in the remote areas of Bikaner, Nagaur, Hanumangarh, Sanchore, Shriganganagar etc. Gypsum and selenite are mined about 3.0 million tons per year. There is huge demand from cement industry as Gypsum is added for improving setting time of cement. Gypsum is a natural fertilizer for alkaline land and it role is vital in state like India where alkaline land is major role. Its high use as fertilizer has potential to change millions of poor farmer families and improving in crop production. Cement Industry has started importing Gypsum from Thailand, Bankong, Pakistan, Iran etc. The mining of gypsum of purity of 70% CaSO4.2H2O is cooperative effort between the land owners and Rajasthan State Mines and Minerals Limited. Gypsum fulfills the demand of POP and Cement industry in Rajasthan and powder gypsum used in agriculture for recon dining of alkaline soil. This paper deals with multiple uses, availability, and future prospective of Gypsum, a white gold of Rajasthan.

  13. Sulphate behaviour from dissolution of gypsum in organic acids

    Baruah, M.K.; Gogoi, P.C.; Kotoky, P. [NNS College, Titabar (India). Dept. of Chemistry


    The solubility of gypsum in organic acids namely acetic, oxalic, tartaric and succinic acids at low temperature (30{degree}C) was studied. The results show that sulphate sulphur content increases with increasing acid concentration from 0.1 to 0.25 M and decreases again at higher concentration. It is suggested that different behaviour of the acids beyond 0.25 M solution could be due to incorporation of sulphate into the co-ordination sphere of calcium-organic complexes. It is suggested that the occurrence of free and fixed sulphate in the solution is highly pH dependent. The nature of incorporation of sulphate in a system containing calcium species and natural organic matter has also been studied. Humic acids, extracted from forest and tea-garden soils, were treated with a solution of gypsum (CaSO{sub 4}.2H{sub 2}O) at room temperature and the infrared spectra of the gypsum treated samples reveal that sulphate has been incorporated into the calcium complex as a monodentate ligand. Further an inorganic-sulphur free high-sulphur coal when treated with the gypsum solution, incorporated sulphate as bidentate ligand. It is concluded that the nature of the organic matter plays an important role for the occurrence of various fixed sulphates either as monodentate or bidentate ligand in natural systems. This work is a novel breakthrough for the occurrence of varying sulphate content in some of the natural environments and has considerable environmental and geochemical interest. Short communication. 46 refs., 3 figs.

  14. Comparison of Energy Dissipation, Stiffness, and Damage of Structural Oriented Strand Board (OSB, Conventional Gypsum, and Viscoelastic Gypsum Shearwalls Subjected to Cyclic Loads

    Andrew S. Blasetti


    Full Text Available A key element in the seismic load resisting system of a wood framed structure is the shear wall which is typically sheathed on one side with plywood or oriented strand board (OSB and gypsum on the other. The shear capacity of gypsum sheathed shear walls is typically neglected in high seismic areas due to the susceptibility of conventional drywall screw connections to damage caused by earthquakes. The earthquake resistance of an innovative viscoelastic (VE gypsum shearwall is evaluated and compared to conventional structural and non-structural walls. Ten 8 ft × 8 ft wood framed wall specimens of three configurations [nailed-OSB, screw-gypsum, and VE polymer-gypsum] were subjected to a cyclic test protocol. The energy dissipation, stiffness, and damage characteristics of all shearwalls are reported herein. Testing results indicate the VE-gypsum walls can dissipate more energy than the OSB structural panels and 500% more energy that the conventional gypsum sheathed walls and contains a constant source of energy dissipation not seen in the structural and non-structural walls. The wall stiffness of the OSB wall degrades at a far greater rate that the VE gypsum wall and at continued cycling degrades below the VE wall stiffness. Unlike both of the conventional wall types, the VE wall showed no visible or audible signs of damage when subjected to shear displacements up to 1.

  15. Manufacturing of calcium phosphate scaffolds by pseudomorphic transformation of gypsum

    Araujo Batista, H. de.; Batista Cardoso, M.; Sales Vasconcelos, A.; Vinicius Lia Fook, M.; Rodriguez Barbero, M. A.; Garcia Carrodeguas, R.


    Carbonated hydroxyapatite (CHAp) and β-tricalcium phosphate (β-TCP) have been employed for decades as constituents of scaffolds for bone regeneration because they chemically resemble bone mineral. In this study, the feasibility to manufacture CHAp/β-TCP scaffolds by pseudomorphic transformation of casted blocks of gypsum was investigated. The transformation was carried out by immersing the precursor gypsum block in 1 M (NH{sub 4}){sub 2}HPO{sub 4}/1.33 M NH{sub 4}OH solution with liquid/solid ratio of 10 mL/g and autoclaving at 120 degree centigrade and 203 kPa (2 atm) for 3 h at least. Neither shape nor dimensions significantly changed during transformation. The composition of scaffolds treated for 3 h was 70 wt.% CHAp and 30 wt.% β-TCP, and their compressive and diametral compressive strengths were 6.5 ± 0.7 and 5.3 ±0.7 MPa, respectively. By increasing the time of treatment to 6 h, the composition of the scaffold enriched in β-TCP (60 wt.% CHAp and 40 wt.% β-TCP) but its compressive and diametral compressive strengths were not significantly affected (6.7 ± 0.9 and 5.4 ± 0.6 MPa, respectively). On the basis of the results obtained, it was concluded that this route is a good approach to the manufacturing of biphasic (CHAp/β-TCP) scaffolds from previously shaped pieces of gypsum. (Author)

  16. Differences in gypsum plant communities associated with habitat fragmentation and livestock grazing.

    Pueyo, Y; Alados, C L; Barrantes, O; Komac, B; Rietkerk, M


    The negative consequences of habitat fragmentation for plant communities have been documented in many regions of the world. In some fragmented habitats, livestock grazing has been proposed to be a dispersal mechanism reducing isolation between fragments. In others, grazing acts together with fragmentation in a way that increases habitat degradation. Iberian gypsum plant communities have been grazed and fragmented by agricultural practices for centuries. Although their conservation is considered a priority by the European Community, the effects of fragmentation on gypsum plant communities and the possible role of livestock grazing remain unknown. In addition, a substantial proportion of plant species growing in gypsum environments are gypsum specialists. They could be particularly affected by fragmentation, as was found for other habitat specialists (i.e., serpentine and calcareous specialists). In this study (1) we investigated the effect of fragmentation and grazing on gypsum plant community composition (species and life-forms), and (2) we tested to see if gypsum specialists were differently affected by fragmentation and grazing than habitat generalists. A vegetation survey was conducted in the largest gypsum outcrop of Europe (Middle Ebro Valley, northeast Spain). Fragmented and continuous sites in grazed and ungrazed areas were compared. Measurements related to species and composition of life-forms were contrasted first for the whole gypsum plant community and then specifically for the gypsum specialists. In the whole community, our results showed lower plant species diversity in fragmented sites, mainly due to the larger dominance of species more tolerant to fragmented habitat conditions. With livestock grazing, the plant species richness and the similarity in plant species composition between remnants was larger, suggesting that animals were acting as dispersal agents between fragments. As expected, gypsum specialists were less abundant in fragmented areas

  17. Crystallisation of Gypsum and Prevention of Foaming in Wet Flue Gas Desulphurisation (FGD) Plants

    Hansen, Brian Brun; Kiil, Søren; Johnsson, Jan Erik


    The aim of this project is to investigate two operational problems, which have been experienced during wet flue gas desulphurisation (FGD) operation, i.e. poor gypsum dewatering properties and foaming. The results of this work can be used for the optimization of wet FGD-plants in terms of reliability of operation and consistency of the gypsum quality obtained. This work may furthermore be of interest to other industrial systems in which foaming or gypsum crystallisation may take place. FGD is...

  18. Investigation of Parameters Affecting Gypsum Dewatering Properties in a Wet Flue Gas Desulphurization Pilot Plant

    Hansen, Brian Brun; Kiil, Søren


    Wet flue gas desulphurization (FGD) plants with forced oxidation, installed at coal and oil fired power plants for removal of SO2(g), must produce gypsum of high quality. However, quality issues such as an excessive moisture content, due to poor gypsum dewatering properties, may occur from time to time. In this work, the particle size distribution, morphology, and filtration rate of wet FGD gypsum formed in a pilot-scale experimental setup, operated in forced oxidation mode, have been studied...

  19. Carbonate replacement of lacustrine gypsum deposits in two Neogene continental basins, eastern Spain

    Anadón, P.; Rosell, L.; Talbot, M. R.


    Bedded nonmarine gypsum deposits in the Miocene Teruel and Cabriel basins, eastern Spain, are partly replaced by carbonate. The Libros gypsum (Teruel Graben) is associated with fossiliferous carbonate wackestones and finely laminated, organic matter-rich mudstones which accumulated under anoxic conditions in a meromictic, permanent lake. The gypsum is locally pseudomorphed by aragonite or, less commonly, replaced by calcite. Low δ 13C values indicate that sulphate replacement resulted from bacterial sulphate reduction processes that were favoured by anacrobic conditions and abundant labile organic matter in the sediments. Petrographic evidence and oxygen isotopic composition suggest that gypsum replacement by aragonite occurred soon after deposition. A subsequent return to oxidising conditions caused some aragonite to be replaced by diagenetic gypsum. Native sulphur is associated with some of these secondary gypsum occurrences. The Los Ruices sulphate deposits (Cabriel Basin) contain beds of clastic and selenitic gypsum which are associated with limestones and red beds indicating accumulation in a shallow lake. Calcite is the principal replacement mineral. Bacterial sulphate reduction was insignificant in this basin because of a scarcity of organic matter. Stable isotope composition of diagenetic carbonate indicates that gypsum replacement occurred at shallow burial depths due to contact with dilute groundwaters of meteoric origin. Depositional environment evidently has a major influence upon the diagenetic history of primary sulphate deposits. The quantity of preserved organic matter degradable by sulphate-reducing bacteria is of particular importance and, along with groundwater composition, is the main factor controlling the mechanism of gypsum replacement by carbonate.

  20. Hydrology of marginal evaporitic basins during the Messinian Salinity Crisis: isotopic investigation of gypsum deposits

    El Kilany, Aida; Caruso, Antonio; Dela Pierre, Francesco; Natalicchio, Marcello; Rouchy, Jean-Marie; Pierre, Catherine; Balter, Vincent; Aloisi, Giovanni


    The deposition of gypsum in Messinian Mediterranean marginal basins is controlled by basin restriction and the local hydrological cycle (evaporation/precipitation rates and relative importance of continental vs marine water inputs). We are using the stable isotopic composition of gypsum as a proxy of the hydrological cycle that dominated at the moment of gypsum precipitation. We studied the Messinian Caltanissetta (Sicily) and Tertiary Piedmont (north western Italy) basins where we carried out a high-resolution isotopic study of gypsum layers composing gypsum-marl cycles. These cycles are thought to be the sedimentary expression of astronomical precession cycles, lasting approximately 20 kyr, during which the marginal basins experienced a succession of arid and a wet conditions. We determined the isotopic composition of gypsum hydration water (18O and D), of the sulphate ion (34S, 18O) and of Strontium (87/86Sr), all of which are potentially affected by the hydrological cycle. In our samples, the mother water from which gypsum precipitated is considerably lighter (-4.0 planning a detailed petrographic investigation of gypsum crystals to look for evidence of dissolution/precipitation processes at the micro-scale. This is an essential step in interpreting the isotopic signals of gypsum because we can expect the 18O and D composition of Messinian continental input to be not too dissimilar from that of modern meteoric waters involved in diagenetic processes.

  1. Ancient gypsum mortars from Cyprus: characterization and reinvention

    Theodoridou, M.; Ioannou, I.


    Mortars with various binding materials have been used across different pre-historic and historic periods to meet several construction applications, such as jointing masonry blocks, finishing walls and isolating water bearing structures. In the framework of an ongoing research programme (NEA ΥΠOΔOMH/NEKΥΠ/0308/17) funded by the Cyprus Research Promotion Foundation, the Republic of Cyprus and the European Union Regional Development Fund, 25 samples of gypsum mortars from different archaeological sites in Cyprus were collected and characterized following a systematic analytical approach. Petrographic observations of thin sections were carried out using polarizing optical microscope. Scanning electron microscopy equipped with energy dispersive X-ray microanalyser (SEM-EDX) was used to examine the microstructure and texture of the mortar samples and to determine semi-quantitatively the chemical composition and interface of their binders. X-ray diffraction (XRD) was performed to identify the main mineral crystalline phases of the specimens' binder and aggregates. Thermal analyses (TG/DTA) were used as a further confirmation of the material composition. The pore structure and volume of the ancient mortars were also determined by mercury intrusion porosimetry (MIP) analysis. Last but not least, a portable drilling resistance measurement system (DRMS) was used for micro-destructive assessment of the mechanical state of the samples. The results confirmed the predominant presence of hydrous calcium sulphate in all samples. Calcite was also found both in the binder and aggregates. Small proportions of SiO2 were also detected. The common ratio of binder to aggregates was 1:2.5. MIP showed porosity values between 14-48% and real densities between 1-1.7 g/cm3. The average pore diameters were smaller in the case of mortars with lower porosity. The use of DRMS indicated lower resistance to drilling for the case of joint mortars (as opposed to analysed gypsum plasters). This

  2. Light in the darkening on Naica gypsum crystals

    Castillo-Sandoval, I.; Fuentes-Cobas, L. E.; Esparza-Ponce, H. E.; Carreno-Márquez, J.; Montero-Cabrera, M. E., E-mail: [Centro de Investigación en Materiales Avanzados (CIMAV), Miguel de Cervantes 120, Chihuahua, Chih 31109, México (Mexico); Fuentes-Montero, M. E. [Facultad de Ciencias Químicas, Universidad Autónoma de Chihuahua, Campus Universitario#2, Circuito Universitario, C.P.31125, Chihuahua, Chih. México (Mexico); Reyes-Cortes, M. [Facultad de Ingeniería. Universidad Autónoma de Chihuahua, Campus Universitario#2, Circuito Universitario, C.P.31125, Chihuahua, Chih. México (Mexico)


    Naica mine is located in a semi-desertic region at the central-south of Chihuahua State. The Cave of Swords was discovered in 1910 and the Cave of Crystals 90 years later at Naica mines. It is expected that during the last century the human presence has changed the microclimatic conditions inside the cave, resulting in the deterioration of the crystals and the deposition of impurities on gypsum surfaces. As a contribution to the clarification of the mentioned issues, the present work refers to the use of synchrotron radiation for the identification of phases on these surfaces. All the experiments were performed at the Stanford Synchrotron Radiation Lightsource. Grazing incidence X-ray diffraction (GIXRD) and radiography-aided X-ray diffraction (RAXRD) experiments were performed at beamline 11-3. X-Ray micro-fluorescence (μ-SXRF) and micro-X-ray absorption (μ-XANES) were measured at beamline 2-3. Representative results obtained may be summarized as follows: a) Gypsum, galena, sphalerite, hematite and cuprite at the surface of the gypsum crystals were determined. b) The samples micro-structure is affected by impurities. c) The elemental distributions and correlations (0.6-0.9) of Cu, K, Fe, Mn, Pb, Zn, Ca and S were identified by μ-SXRF. The correlations among elemental contents confirmed the phase identification, with the exception of manganese and potassium due to the amorphous nature of some impurity compounds in these samples. The compounds hematite (Fe{sub 2}O{sub 3}), β-MnO{sub 2}, Mn{sub 2}O{sub 3}, MnO and/or MnCO{sub 3}, PbS, PbCO{sub 3} and/or PbSO4, ZnO{sub 4}, ZnS and/or smithsonite (ZnCO{sub 3}), CuS + Cu Oxide were identified by XANES. Plausibly, these latter compounds do not form crystalline phases.

  3. Luminescence of Speleothems in Italian Gypsum Caves: Preliminary Report

    Shopov, Yavor Y; Forti, Paolo


    The luminescence of 3 speleothem samples from the Acquafredda karst system and 1 from the Novella Cave (Gessi Bolognesi Natural Park, Italy) has been recorded using excitation by impulse Xe- lamp. All these carbonate speleothems are believed to be formed only from active CO2 from the air, because the bedrock of the cave consist of gypsum and does not contain carbonates. The obtained photos of luminescence record the climate changes during the speleothem growth. U/Th and 14C dating proved that studied speleothems started to grow since about 5,000 years ago. The detailed analyses of the luminescence records is still in progress.

  4. Synthesis of partial stabilized cement-gypsum as new dental retrograde filling material

    Sadhasivam, S. [Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan (China); Division of Medical Engineering Research, National Health Research Institute, Zhunan, Miaoli County, Taiwan (China); Chen, Jung-Chih [Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan (China); Medical Device Innovation Center, National Cheng Kung University, Tainan,Taiwan (China); Savitha, S. [Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan (China); Hsu, Ming-Xiang; Hsu, Chung-King [Institute of Materials Science and Engineering, National Taipei University of Technology, Taipei, Taiwan (China); Lin, Chun-Pin [School of Dentistry and Graduate Institute of Clinical Dentistry, College of Medicine, National Taiwan University and National Taiwan University Hospital, Taipei, Taiwan (China); Lin, Feng-Huei, E-mail: [Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan (China); Division of Medical Engineering Research, National Health Research Institute, Zhunan, Miaoli County, Taiwan (China)


    The study describes the sol-gel synthesis of a new dental retrograde filling material partial stabilized cement (PSC)-gypsum by adding different weight percentage of gypsum (25% PSC + 75% gypsum, 50% PSC + 50% gypsum and 75% PSC + 25% gypsum) to the PSC. The crystalline phase and hydration products of PSC-gypsum were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. The handling properties such as setting time, viscosity, tensile strength, porosity and pH, were also studied. The XRD and microstructure analysis demonstrated the formation of hydroxyapatite and removal of calcium dihydrate during its immersion in simulated body fluid (SBF) on day 10 for 75% PSC + 25% gypsum. The developed PSC-gypsum not only improved the setting time but also greatly reduced the viscosity, which is very essential for endodontic surgery. The cytotoxic and cell proliferation studies indicated that the synthesized material is highly biocompatible. The increased alkaline pH of the PSC-gypsum also had a remarkable antibacterial activity. - Highlights: Black-Right-Pointing-Pointer A new dental retrograde filling material PSC-gypsum was developed. Black-Right-Pointing-Pointer PSC-gypsum cement has shown excellent initial and final setting time as 15-35 min. Black-Right-Pointing-Pointer It not only improved the setting time but also retain the viscosity, 2 Pa{center_dot}s. Black-Right-Pointing-Pointer High alkaline pH of the cement had a remarkable antibacterial activity. Black-Right-Pointing-Pointer Cytotoxicity studies revealed that the synthesized material is highly biocompatible.

  5. Limestone, gypsum, and magnesium oxide influence restoration of an abandoned Appalachian pasture

    Ritchey, K.D.; Snuffer, J.D. [USDA ARS, Beaver, WV (United States). Appalachian Farming Systems Research Centre


    When restoring abandoned pastures on acidic hill-land soils to productivity, it is important to bring soil Ca and Mg to adequate levels. Gypsum is a readily available Ca amendment that is sufficiently soluble to move rapidly into the soil when surface-applied. Gypsum has been shown to reduce detrimental effects of subsurface acidity in soils of the southeastern USA. A 4-yr experiment was initiated to measure effects of surface gypsum application on forage production and to evaluate Mg-containing amendments to avoid gypsum-induced Mg deficiency. The study site was a southern West Virginia Gilpin silt loam (fine-loamy, mixed, mesic, Typic Hapludult) where abandoned hill-and pasture was being restored to productivity. Treatments included 0, 1000, 8000; 16 000, and 32 000 kg/ha flue gas desulfurization coal combustion by-product gypsum (gypsum) together with dolomitic limestone and five additional treatments to evaluate sources of supplemental Mg. Application of 16 000 kg/ha gypsum together with limestone increased forage yields of mixed orchardgrass (Dactylis glomerata L.) and tall fescue (Festuca arundinacea Schreb) pasture during establishment by 42% and production by 11% compared with limestone alone. About 8% of the mean 790 kg/ha yield increase could be attributed to acidity-neutralizing effects of alkaline constituents in the gypsum by-product. Plants in higher gypsum treatments had higher concentrations of K and P, but gypsum application decreased soil and plant Mg concentrations. This indicated that gypsum should not be applied on typical acid soils without supplemental Mg.

  6. Direct nanoscale observations of the coupled dissolution of calcite and dolomite and the precipitation of gypsum.

    Offeddu, Francesco Giancarlo; Cama, Jordi; Soler, Josep Maria; Putnis, Christine V


    In-situ atomic force microscopy (AFM) experiments were performed to study the overall process of dissolution of common carbonate minerals (calcite and dolomite) and precipitation of gypsum in Na2SO4 and CaSO4 solutions with pH values ranging from 2 to 6 at room temperature (23 ± 1 °C). The dissolution of the carbonate minerals took place at the (104) cleavage surfaces in sulfate-rich solutions undersaturated with respect to gypsum, by the formation of characteristic rhombohedral-shaped etch pits. Rounding of the etch pit corners was observed as solutions approached close-to-equilibrium conditions with respect to calcite. The calculated dissolution rates of calcite at pH 4.8 and 5.6 agreed with the values reported in the literature. When using solutions previously equilibrated with respect to gypsum, gypsum precipitation coupled with calcite dissolution showed short gypsum nucleation induction times. The gypsum precipitate quickly coated the calcite surface, forming arrow-like forms parallel to the crystallographic orientations of the calcite etch pits. Gypsum precipitation coupled with dolomite dissolution was slower than that of calcite, indicating the dissolution rate to be the rate-controlling step. The resulting gypsum coating partially covered the surface during the experimental duration of a few hours.

  7. Gypsum's influence on corn yield and p loss from an eroded southern piedmont soil

    Gypsum (CaSO4) has been shown to reduce dissolved P in surface water runoff from pastures fertilized with poultry litter (PL). However, limited research has evaluated gypsum’s influence on P loss under row crops. Moreover, can gypsum effectively reduce P loss when applied only to grass buffer strips...

  8. The Growth of Gypsum in the Presence of Hexavalent Chromium: A Multiscale Study

    Juan Morales


    Full Text Available The sorption of dissolved inorganic pollutants into the structure of minerals is an important process that controls the mobility and fate of these pollutants in the Earth’s crust. It also modifies the surface structure and composition of the host mineral, affecting its crystallization kinetics. Here, we investigate the effect of hexavalent chromium, Cr(VI, on the nucleation and growth of gypsum by conducting two types of experiments: (i in situ atomic force microscopy (AFM observations of the growth of gypsum {010} surfaces in the presence of Cr(VI and (ii gypsum precipitation experiments by mixing aqueous solutions containing variable amounts of Cr(VI. Gypsum precipitation is progressively delayed when occurring from solutions bearing increasing Cr(VI concentrations. Chemical analyses of gypsum precipitates show that gypsum incorporates small Cr(VI amounts that correlate with the content of this ion in the aqueous solution. Gypsum cell parameters variation reflects this incorporation. At the molecular scale, Cr(VI induces a slowdown of step advance rates on gypsum {010} surfaces accompanied by the roughening of nanostep edges and the so-called “template effect”. This effect involves the reproduction of the original nanotopography after the completion of individual advancing monolayers and appears as a general nanoscale phenomenon occurring during growth of solid solutions from aqueous solutions even in the case of compositionally-restricted solid solutions.

  9. Use of Deep Peat-Processing Products for Hydrophobic Modification of Gypsum Binder

    Misnikov Oleg


    Full Text Available The article deals with the issue of gypsum binder quality reduction during its storage and transportation. The study provides the main methods to protect gypsum from unauthorized exposure to moisture and water vapor. The author proposes hydrophobic modification as a perspective method for the preservation of gypsum activity and its water absorption reduction. The substantiation of cement hydrophobization with the bitumen released during peat thermolysis is provided. The author proposes to use this method in the technology of gypsum binder production. The basic idea is to combine the hydrophobization process with the calcination of calcium sulfate dehydrate. This is facilitated by temperature ranges used for dehydration of natural gypsum and the initial stage of thermal decomposition of the organic matter of peat. The author defined experimentally an optimal concentration of the organic component in gypsum binder. After adding 0.5-1% of the peat additive, the gypsum plaster preserved its grade strength and increased its storage time without caking and hydration, also under adverse conditions. The proposed method is adapted to the technological processes presently used in the production and doesn’t require changing any equipment. The price of mineral raw materials and semi-finished products of peat are approximately equal which reduces the probability of increasing of the cost of hydrophobically modified gypsum binder.

  10. Pre-contamination of new gypsum wallboard with potentially harmful fungal species

    Andersen, Birgitte; Dosen, Ina; Lewinska, Anna Malgorzata;


    Gypsum wallboard is a popular building material, but is also very frequently overgrown by Stachybotrys chartarum after severe and/or undetected water damage. The purpose of this study was to determine whether Stachybotrys and other fungi frequently isolated from wet gypsum wallboard are already p...

  11. Authigenic gypsum in a deep sea core from Southeastern Arabian Sea

    Guptha, M.V.S.

    Authigenic gypsum has been encountered in a deep sea core RC9-157 from the southeastern Arabian Sea at a depth of 4111 m which is a zone of lysocline. The formation of gypsum in the deep sea region is attributed to the prevailing sulphate rich...

  12. Impact of FGD gypsum on soil fertility and plant nutrient uptake

    Use of FGD gypsum is thought to improve soil productivity and increase plant production. Thus, a study was conducted to evaluate the effects of FGD gypsum on yield, plant nutrient uptake and soil productivity. The study was conducted on an established bermudagrass pasture. Poultry litter was applied...

  13. Microstructure and mechanical properties of gypsum composites reinforced with recycled cellulose pulp

    Magaly Araújo Carvalho


    Full Text Available The use of waste fibers for the reinforcement of brittle matrices is considered opportune for the sustainable management of urban solid residues. This paper examines the microstructure and mechanical properties of a composite material made of gypsum reinforced with cellulose fibers from discarded Kraft cement bag. Two different kinds of gypsum were used, natural gypsum (NG and recycled gypsum (RG, both with an addition of 10% by mass of limestone. For the production of samples, slurry vacuum de-watering technique followed by pressing was evaluated revealing to be an efficient and innovative solution for the composites under evaluation. The composite was analyzed based on flexural strength tests, scanning electron microscopy (SEM imaging, secondary electron (SE detection, and pseudo-adiabatic calorimetry. The morphology of the fractured surfaces of flexural test samples revealed large gypsum crystals double the original size surrounding the fibers, but with the same overall aspect ratio. Natural fibers absorb large amounts of water, causing the water/gypsum ratio of the paste to increase. The predominance of fiber pullout, damaged or removed secondary layers and incrusted crystals are indicative of the good bonding of the fiber to the gypsum matrix and of the high mechanical resistance of composites. This material is a technically better substitute for the brittle gypsum board, and it stands out particularly for its characteristics of high impact strength and high modulus of rupture.

  14. An important tool with no instruction manual: A review of gypsum use in agriculture

    Land application of gypsum has been studied and utilized in agriculture and environmental remediation for many years. Most of the published literature has focused on gypsum application impacts on soil properties rather than crop yields. This literature review was conducted to (i) gather results from...

  15. Pre-contamination of new gypsum wallboard with potentially harmful fungal species

    Andersen, Birgitte; Dosen, Ina; Lewinska, Anna Malgorzata


    Gypsum wallboard is a popular building material, but is also very frequently overgrown by Stachybotrys chartarum after severe and/or undetected water damage. The purpose of this study was to determine whether Stachybotrys and other fungi frequently isolated from wet gypsum wallboard are already p...

  16. Calcium sulfoaluminate (Ye'elimite) hydration in the presence of gypsum, calcite, and vaterite

    Hargis, Craig W. [Department of Civil and Environmental Engineering, University of California, Berkeley, CA (United States); Telesca, Antonio [School of Engineering, University of Basilicata, Potenza (Italy); Monteiro, Paulo J.M., E-mail: [Department of Civil and Environmental Engineering, University of California, Berkeley, CA (United States)


    Six calcium sulfoaluminate-based cementitious systems composed of calcium sulfoaluminate, calcite, vaterite, and gypsum were cured as pastes and mortars for 1, 7, 28 and 84 days. Pastes were analyzed with X-ray diffraction, thermogravimetric and differential thermal analyses. Mortars were tested for compressive strength, dimensional stability and setting time. Furthermore, pastes with a water/cementitious material mass ratio of 0.80 were tested for heat evolution during the first 48 h by means of isothermal conduction calorimetry. It has been found that: (1) both calcite and vaterite reacted with monosulfoaluminate to give monocarboaluminate and ettringite, with vaterite being more reactive; (2) gypsum lowered the reactivity of both carbonates; (3) expansion was reduced by calcite and vaterite, irrespective of the presence of gypsum; and (4) both carbonates increased compressive strength in the absence of gypsum and decreased compressive strength less in the presence of gypsum, with vaterite's action more effective than that of calcite.

  17. The gypsum-brushite system: crystallization from solutions poisoned by phosphate ions

    Rinaudo, C.; Lanfranco, A. M.; Boistelle, R.


    Gypsum and a non-stoichiometric calcium phosphate sulphate hydrate (CPSH) were grown from solutions poisoned by phosphate ions. The pH ranged from 4.7 to 5.6 and the sulphate over phosphate ratios from 1.5 to 9. In some cases, when the phosphate concentration was high (30%-40%) CPSH was stable. When the phosphate concentration was lower (10%-20%), CPSH formed as first phase in association with gypsum, but dissolved as soon as gypsum crystallized and grew at its expense. In that case, gypsum contained up to 10% phosphate. On the other hand, when gypsum crystallized alone, as first phase, it did not contain detectable amounts of phosphate.

  18. Alleviation of Subsoil Acidity of Red Soil in Southeast China with Lime and Gypsum



    Application of lime or gypsum is a common agricultrual practice to ameliorate soils with low pH which prohibits crop prduction,Its integrated effect on soil properties in a red soil derved from Quaternary red clay in Southeast China is discussed in this paper,Application of gypsum in the topsoil without leaching raised soil pH and promoted the production of soil NH4,but lime addition had a contrary effect.Generally,application of lime and /or gypsum has little on soil electrical properties.Gypsum had a little effect on soil exchange complex and its effect went down to 30 cm in depth ,The effect of lime reached only to 5 cm below its application layer.With leaching,Ca transferred from top soil to subsoil and decreased exchangeable Al in subsiol.Gypsum application led to a sharp decrease in soil exchangeable Mg but had no effect on K.

  19. Heat storage in gypsum. Final report to the Energy Agency; Vaermelagring i Gips. Slutrapport foer Energimyndigheten

    Chaudhuri, Punya (Process Improvements, Plankgatan 26, Norrkoeping (Sweden)); Kindh, Torgny (Environnet AB, Norrkoeping (Sweden)); Lawrence, David; Wahlstroem, Krister (Dept. of Physics, Chemistry and Biology, Linkoeping Univ., Linkoeping (Sweden))


    The Swedish Energy Agency's project 'energy storage in gypsum', began in April 2007 and finished a year later. The objective was to demonstrate the potential of using gypsum to store and retrieve low-grade heat at a pilot scale (i.e. using 200 kg of gypsum). Gypsum undergoes a reversible reaction with water in which it stores or releases energy. Preliminary work indicated that when using commercially available gypsum powder, a packed bed would not allow sufficient mass or heat transfer. Preliminary work also revealed that simple fluidization was not possible with the very fine particles: stirred fluidization was the solution used. A pilot-scale unit was constructed (essentially a closed tank about 1 m in diameter and 1 m high). To store energy, hot, dry air is contacted with the gypsum to bring the temperature of the powder to about 110 deg C. Once the powder is 'dried' it is returned to room temperature and isolated from the surroundings - in this state energy is stored indefinitely. To recover the heat, water was atomized, mixed with warm air (to vaporize the water) and reacted with the gypsum. Typically we were able to recover about 6 kWh of energy, which is only about 20% of what is possible. This is partly the result of too little insulation on the reactor and a hesitation to over-hydrate the gypsum (which would result in solid plaster). We anticipate that this will at least double with increased operating experience. Overall gypsum behaves at a pilot scale as was expected; in terms of energy storage for space heating, it shows great promise. Our experiences to date have shown that using gypsum with a larger particle size (to allow simple fluidization) is an important improvement.

  20. The role of biofilms in the sedimentology of actively forming gypsum deposits at Guerrero Negro, Mexico.

    Vogel, Marilyn B; Des Marais, David J; Turk, Kendra A; Parenteau, Mary N; Jahnke, Linda L; Kubo, Michael D Y


    Actively forming gypsum deposits at the Guerrero Negro sabkha and saltern system provided habitats for stratified, pigmented microbial communities that exhibited significant morphological and phylogenetic diversity. These deposits ranged from meter-thick gypsum crusts forming in saltern seawater concentration ponds to columnar microbial mats with internally crystallized gypsum granules developing in natural anchialine pools. Gypsum-depositing environments were categorized as forming precipitation surfaces, biofilm-supported surfaces, and clastic surfaces. Each surface type was described in terms of depositional environment, microbial diversity, mineralogy, and sedimentary fabrics. Precipitation surfaces developed in high-salinity subaqueous environments where rates of precipitation outpaced the accumulation of clastic, organic, and/or biofilm layers. These surfaces hosted endolithic biofilms comprised predominantly of oxygenic and anoxygenic phototrophs, sulfate-reducing bacteria, and bacteria from the phylum Bacteroidetes. Biofilm-supported deposits developed in lower-salinity subaqueous environments where light and low water-column turbulence supported dense benthic microbial communities comprised mainly of oxygenic phototrophs. In these settings, gypsum granules precipitated in the extracellular polymeric substance (EPS) matrix as individual granules exhibiting distinctive morphologies. Clastic surfaces developed in sabkha mudflats that included gypsum, carbonate, and siliclastic particles with thin gypsum/biofilm components. Clastic surfaces were influenced by subsurface brine sheets and capillary evaporation and precipitated subsedimentary gypsum discs in deeper regions. Biofilms appeared to influence both chemical and physical sedimentary processes in the various subaqueous and subaerially exposed environments studied. Biofilm interaction with chemical sedimentary processes included dissolution and granularization of precipitation surfaces, formation of

  1. Gypsum effects on crop yield and chemistry of soil, crop tissue, and vadose zone water: A meta-analysis.

    Gypsum has various potential benefits as a soil amendment, but data are lacking on gypsum effects on crop yields and on environmental impacts across diverse field sites. Gypsum studies were conducted in six states using a common design with three rates each of mined and flue gas desulfurization (FGD...

  2. PPF-reinforced, ESP-lightened gypsum plaster

    García Santos, A.


    Full Text Available A new construction material has been obtained by adding aggregate to gypsum plaster which, without reducing the bending strength of plain gypsum plaster without aggregates, lowers its density, and consequently the weight of the construction elements made from the agglomerated material, by half.The aggregates used were expanded polystyrene beads and short polypropylene fibre.The new material addresses one of the issues of cardinal interest in construction materials and construction element research, namely the need to lighten materials so as to ease the burden on buildings’ bearing structures while facilitating assembly of construction units, by a single worker wherever possible.With a water / binder ratio of 0.7 and 2% (by weight of plaster of expanded polystyrene and 2% of polypropylene fibre aggregates, the decline in density achieved was 50,88% over plain gypsum plaster and 32.88% over plasterboard.Se ha obtenido un nuevo material de construcción aditivando el yeso o la escayola, mediante la incorporación de agregados, de modo que sin reducir la resistencia a flexotracción de una escayola sin ningún tipo de adición, reduce su densidad a la mitad, y por tanto, el peso de los elementos constructivos que puedan realizarse basándose en él.El material está compuesto por una adición de gránulos de poliestireno expandido y fibras cortadas de polipropileno.El nuevo material incide sobre aquellos aspectos de más interés en el campo de la investigación en construcción, en donde se intenta reducir el peso de los materiales, de modo que se grave lo menos posible la estructura resistente de las edificaciones, a la par que se facilitan los procedimientos de montaje de las unidades constructivas, al poder ser manejadas por un solo operario.La escayola, con relación de agua/conglomerante de 0,7, y con adiciones del 2% en peso (sobre la cantidad de escayola, tanto de poliestireno expandido como de fibras de polipropileno, permite reducir la

  3. XRD and mineralogical analysis of gypsum dunes at White Sands National Monument, New Mexico and applications to gypsum detection on Mars

    Lafuente, B.; Bishop, J. L.; Fenton, L. K.; King, S. J.; Blake, D.; Sarrazin, P.; Downs, R.; Horgan, B. H.


    A field portable X-ray Diffraction (XRD) instrument was used at White Sands National Monument to perform in-situ measurements followed by laboratory analyses of the gypsum-rich dunes and to determine its modal mineralogy. The field instrument is a Terra XRD (Olympus NDT) based on the technology of the CheMin (Chemistry and Mineralogy) instrument onboard the Mars Science Laboratory (MSL) rover Curiosity which is providing the mineralogical and chemical composition of scooped soil samples and drilled rock powders collected at Gale Crater [1]. Using Terra at White Sands will contribute to 'ground truth' for gypsum-bearing environments on Mars. Together with data provided by VNIR spectra [2], this study clarifies our understanding of the origin and history of gypsum-rich sand dunes discovered near the northern polar region of Mars [3]. The results obtained from the field analyses performed by XRD and VNIR spectroscopy in four dunes at White Sands revealed the presence of quartz and dolomite. Their relative abundance has been estimated using the Reference Intensity Ratio (RIR) method. For this study, particulate samples of pure natural gypsum, quartz and dolomite were used to prepare calibration mixtures of gypsum-quartz and gypsum-dolomite with the 90-150μm size fractions. All single phases and mixtures were analyzed by XRD and RIR factors were calculated. Using this method, the relative abundance of quartz and dolomite has been estimated from the data collected in the field. Quartz appears to be present in low amounts (2-5 wt.%) while dolomite is present at percentages up to 80 wt.%. Samples from four dunes were collected and prepared for subsequent XRD analysis in the lab to estimate their composition and illustrate the changes in mineralogy with respect to location and grain size. Gypsum-dolomite mixtures: The dolomite XRD pattern is dominated by an intense diffraction peak at 2θ≈36 deg. which overlaps a peak of gypsum, This makes low concentrations of dolomite

  4. Corrosion of bare and galvanized steel in gypsum

    Gómez, Mercedes


    Full Text Available Gypsum is a relatively low-cost building material much abounding in our country. When it is put in contact with steel, it may produce high corrosion rates due to its pH value (close to 7. This work reports the results obtained in studying the corrosion rates of bare and galvanized steel in contact with gypsum and plaster, as well as the influence curing thermal treatment applied to gypsum, enviromental relative humidity and addition of compounds with different natures and purposes may have in such process. In-situ observations, as well as the measurement of the Polarization Resistance and the weight loss have been used as measurement technics. From the results obtained it has been possible to deduce that galvanized steel has better behaviour in dry enviroments than bare steel in the same conditions and moist atmosphere induces proportionally more corrosion in galvanized steel than in bare one. Additions to gypsum do not modified these conclusions, though it may be pointed out that addition of nitrites or lime improves the behaviour of bare steel, while galvanized behaviour is not modified. The addition of lime is not recommended because phenomena of dilated along time expansion may take place.

    El yeso es un material de construcción de relativo bajo coste y que, además, es muy abundante en nuestro país. Debido a su pH cercano a la neutralidad, cuando entra en contacto con el acero, este puede corroerse a elevadas velocidades. En esta comunicación se presentan los resultados de un estudio sobre la velocidad de corrosión del acero desnudo y galvanizado en contacto con yeso y escayola y la influencia que tienen: el tratamiento térmico del curado del yeso, la humedad relativa ambiental y la adición de aditivos de diversa naturaleza y finalidad. Como técnicas de medida se han utilizado la medida de la Resistencia de Polarización y de la pérdida de peso, así como observaciones visuales. De los resultados se puede deducir que en

  5. Constructive applications of composite gypsum reinforced with Typha Latifolia fibres

    Garcia Santos, A.


    Full Text Available The present research analyses the possibility to reinforce gypsum using enea fibres (Typha Latifolia creating a compound material in wich the fibres contribute to increase mechanical resistance, producing as well a reduction of the weight and a possible regulation of the set time.

    La investigación presente analiza la posibilidad de reforzar los morteros de escayola mediante la utilización dé fibras de Typha Latifolia, creando un material compuesto en el que las fibras contribuyen al aumento de resistencia mecánica, a la vez que se produce una reducción del peso y una regulación de los tiempos de fraguado. Las propiedades de estos materiales hacen que, en determinadas aplicaciones, su utilización resulte ventajosa con respecto a materiales tradicionales.

  6. Calcium Sulfates at Gale Crater and Limitations on Gypsum Stability

    Vantiman, D. T.; Martinez, G. M.; Rampe, E. B.; Bristow, T. F.; Blake, D. F.; Yen, A. H.; Ming, D. W.; Rapin, W.; Meslin, P. -Y.; Morookian, J. M.; hide


    The Mars Science Laboratory rover has been exploring sedimentary rocks of the Bradbury group and overlying Murray formation, as well as the unconformably overlying Stimson formation. Early in exploration, and continuing to present, there have been observations of many Ca-sulfate veins that cut all three stratigraphic units. The CheMin XRD instrument on Curiosity provides complete mineralogy for drilled or scooped samples, with explicit identification of gypsum, bassanite, and anhydrite (crystal structure of so-called "soluble anhydrite," or gamma-CaSO4, is so similar to bassanite that it can't be distinguished at CheMin 2-theta resolution; here we refer to these similar dehydrated forms simply as bassanite).

  7. Carbonate speleothems from western Mediterranean gypsum karst: palaeoclimate implications

    Columbu, Andrea; Drysdale, Russell; Woodhead, Jon; Chiarini, Veronica; De Waele, Jo; Hellstrom, John; Forti, Paolo; Sanna, Laura


    Gypsum caves are uncommon environments for carbonate speleothems (cave deposits). Contrary to limestone caves, the only source of non-atmospheric carbon is from biogenic CO2 produced by the overlying soils. Enhanced CO2 content in soils is in turn related with climate, where warm temperatures and high humidity favour plant activity .().....(Fairchild and Baker, 2012). Although poorly decorated, the exploration of northern Italian and Spanish gypsum karst systems reveals the existence of several generations of carbonate speleothems, which have been dated with the U-Th series method .()......(Hellstrom, 2003; Scholz and Hoffmann, 2008). Their ages coincide with current and previous two interglacials (MIS 1, 5e and 7e and Greenland interstadials (GIS) 19, 20, 21 and 24. Considering that these periods are amongst the most pronounced warm-wet pulsations over the last 250,000 ...(Martrat et al., 2007; NGRIP, 2004), and that CO2 has a fundamental role in this karst process, this study explores the climate-driven hydrogeological conditions necessary to trigger carbonate deposition in gypsum voids. The further correlation with sapropel events 5, 4, 3 and 1, considered symptomatic of enhanced rainfall across the whole Mediterranean basin .(.)(Emeis et al., 1991), highlights the importance of flow-rate in the fracture network and infiltration of meteoric water into the caves. The combination of high CO2 and a phreatic status of the fracture network is thus indispensable for the formation of carbonate speleothems in gypsum karst. This condition appears to be triggered by periods of orbital precession minimum, when the monsoonal activity peaked in the Atlantic area. Stable oxygen isotope signatures suggest that the speleothems did not grow during any interglacial-glacial or main interstadial-stadial transitions, confirming that variations from optimum climate conditions may hamper the formation of this category of speleothems. New speleological exploration and sampling campaign

  8. Enhanced gypsum scaling by organic fouling layer on nanofiltration membrane: Characteristics and mechanisms.

    Wang, Jiaxuan; Wang, Lei; Miao, Rui; Lv, Yongtao; Wang, Xudong; Meng, Xiaorong; Yang, Ruosong; Zhang, Xiaoting


    To investigate how the characteristics of pregenerated organic fouling layers on nanofiltration (NF) membranes influence the subsequent gypsum scaling behavior, filtration experiments with gypsum were carried out with organic-fouled poly(piperazineamide) NF membranes. Organic fouling layer on membrane was induced by bovine serum albumin (BSA), humic acid (HA), and sodium alginate (SA), respectively. The morphology and components of the scalants, the role of Ca(2+) adsorption on the organic fouling layer during gypsum crystallization, and the interaction forces of gypsum on the membrane surface were investigated. The results indicated that SA- and HA-fouled membranes had higher surface crystallization tendency along with more severe flux decline during gypsum scaling than BSA-fouled and virgin membranes because HA and SA macromolecules acted as nuclei for crystallization. Based on the analyses of Ca(2+) adsorption onto organic adlayers and adhesion forces, it was found that the flux decline rate and extent in the gypsum scaling experiment was positively related to the Ca(2+)-binding capacity of the organic matter. Although the dominant gypsum scaling mechanism was affected by coupling physicochemical effects, the controlling factors varied among foulants. Nevertheless, the carboxyl density of organic matter played an important role in determining surface crystallization on organic-fouled membrane.

  9. The effects of K2SO4 solution on the compressive strength of dental gypsum type III

    Adeilina, T.; Triaminingsih, S.; Indrani, D. J.


    Dental gypsum type III is used as a material for manufacturing working models of dentures. The aim of this study was to identify the effects of the addition of a K2SO4 solution on the compressive strength of gypsum type III. A compressive strength test was performed using a universal testing machine with a crosshead speed of 1 mm/min. The data were analyzed using a one-way ANOVA. The results showed that the compressive strength of gypsum type III with a 1.5% K2SO4 solution added was higher than for gypsum type III alone but lower than the compressive strength of gypsum type IV.

  10. Influence of shelf life on the setting time of type IV gypsum

    Hapsari, M. L.; Irawan, B.; Damiyanti, M.


    Although expired materials can exhibit a deterioration in their properties, expired type IV gypsum can still be found on the market. In order to evaluate the influence of the shelf life on its setting time, two groups of type IV gypsum (GC Fuji rock EP) with different expiration dates were used in this research. The setting time tests were done in a mold using a Vicat Needle apparatus. The results of the statistical analysis showed a significant difference (p<0.05) between the two different expiration date groups. Therefore, the shelf life did influence the setting time of the type IV gypsum.

  11. Activation of Anhydrate Phosphogypsmn by K2SO4 and Hemihydrate Gypsum

    YANG Min; QIAN Jueshi


    Lime pretreated phosphogypsum(PG) was calcined at 500 ℃ to produce anhydrate gypsum cement.Due to the slow hydration of anhydrate gypsum,additives,K2SO4 and hemihydrate gypsum were selected to accelerate the hydration of anhydrate.The hydration characteristics,the resistance to hydrodynamic water,and the mineralogical studies were investigated.The experimental results suggest that activated by K2SO4 and hemihydrate,anhydrate PG hydrates much more rapidly than that in the presence of only K2SO4 or in the absence of additives.The binder has proper setting time,good strength development,and relatively better resistance to water.The hardened binder has hydrated products of rod or stick like shaped dihydrate gypsum crystals.

  12. Investigation of the gypsum quality at three full-scale wet flue gas desulphurisation plants

    Hansen, Brian Brun; Kiil, Søren; Johnsson, Jan Erik


    In the present study the gypsum (CaSO4·2H2O) quality at three full-scale wet flue gas desulphurisation (FGD) plants and a pilot plant were examined and compared. Gypsum quality can be expressed in terms of moisture content (particle size and morphology dependent) and the concentration of residual...... or accumulation of fly ash and impurities from the sorbent. The crystal morphology obtained in the pilot plant was columnar with distinct crystal faces as opposed to the rounded shapes found at the full-scale plants. All the investigated full-scale plants consistently produced high quality gypsum (High purity......, low moisture content and low impurity content). An episode concerning a sudden deterioration in the gypsum dewatering properties was furthermore investigated, and a change in crystal morphology, as well as an increased impurity content (aluminium, iron and fluoride), was detected....

  13. Primary Evaporites for the Messinian Salinity Crisis: the shallow gypsum vs. deep dolomite formation paradox solved

    De Lange, Gert J.; Krijgsman, Wout


    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

  14. Heat transfer and thermal storage behaviour of gypsum boards incorporating micro-encapsulated PCM

    Lai, Chi-ming [Department of Civil Engineering, National Cheng-Kung University, 1, University Road, Tainan City 701 (China); Chen, R.H.; Lin, Ching-Yao [Department of Mechanical Engineering, Southern Taiwan University (China)


    In the application of energy storage and thermal environmental control, PCM (Phase Change Material) is a very promising material choice. This study incorporated mPCM (micro-encapsulated PCM) into gypsum to make mPCM gypsum board and then investigated the physical properties, heat transfer and thermal storage behaviour. The major control parameters are wall temperatures and the weight percentages of mPCM added to the gypsum boards. A melting fraction correlation, reduced from our test data and based on Stefan number (Ste), subcooling (Sb) and Fourier number, is proposed. It shows that case with a higher Ste or Sb can have a higher heat transfer through the hot wall. Thermal storage behaviour of mPCM gypsum boards is then analyzed. (author)

  15. Characterization of gypsum plasterboard with polyurethane foam waste reinforced with polypropylene fibers

    L. Alameda


    Full Text Available Gypsum plasterboard that incorporates various combinations of polyurethane foam waste and polypropylene fibers in its matrix is studied. The prefabricated material was characterized in a series of standardized tests: bulk density, maximum breaking load under flexion stress, total water absorption, surface hardness, thermal properties, and reaction to fire performance. Polypropylene fibers were added to the polyurethane gypsum composites to improve the mechanical behavior of the plasterboard under loading. The results indicate that increased quantities of polymer waste led to significant reductions in the weight/surface ratio, the mechanical strength and the surface hardness of the gypsum, as well as improving its thermal resistance. The polypropylene fibers showed good adhesion to the polymer and the gypsum matrix, which enhanced the mechanical performance and the absorption capacity of these compounds. The non-combustibility test demonstrated the potential of the new material for use in internal linings.

  16. Fossil-fired steam/electric gypsum plant + wallboard plant + powerplant = win-win-win



    The Tennessee Valley Authority has invested in a wall board plant adjacent to its Cumberland power plant to process gypsum slurry. Synmat built the gypsum processing plant to dewater and concentrate the slurry to produce gypsum cake; Temple-Inland build a wallboard plant on 124 acres nearby, the two facilities being linked by conveyor. A 20-ft-high hill of gypsum that had accumulated since 1994 and 1999 when the wallboard plant was built is utilized to meet shortfalls in raw material. The slurry is retrieved from a 10-ft deep water-filled pit that was dug into the stockpile to accept an unmanned floating pump dredge and then pumped through a 6-in line to the Synmat plant. 3 photos.

  17. Coal Combustion Residual Beneficial Use Evaluation: Fly Ash Concrete and FGD Gypsum Wallboard

    This page contains documents related to the evaluation of coal combustion residual beneficial use of fly ash concrete and FGD gypsum wallboard including the evaluation itself and the accompanying appendices

  18. Final Critical Habitat for the Gypsum wild-buckwheat (Eriogonum gypsophilum)

    US Fish and Wildlife Service, Department of the Interior — To provide the user with a general idea of areas where final critical habitat for gypsum wild-buckwheat (Eriogonum gypsophilum) occur based on the description...

  19. Gypsum-induced decay in granite monuments in Northwestern Spain

    Silva Hermo, B.


    Full Text Available One of the most common forms of decay in granite monuments is the detachment of the superficial layer of the stone (plaques, plaquettes and scales. Previous studies of granite monuments in the northwest Iberian Peninsula revealed a direct relation between this type of weathering and the presence of calcium sulphate, and a mechanism whereby the salt causes this type of decay was suggested. In the present study, various hypotheses as regards the origin of the gypsum found in granite monuments are proposed. The study involved analysis of the contents of ions soluble in water, the results of X-ray diffraction analyses and the ratios of CaO/SO3 in samples of stone, mortar and deposits collected from different monuments. It was concluded that in most cases the gypsum originated from old paintworks or/and from the joint mortars, although inputs from other sources cannot be discounted, as discussed

    Una de las formas de deterioro más frecuente en los monumentos graníticos es la separación de la capa superficial de la piedra (placas, plaquetas y escamas. En trabajos anteriores centrados en monumentos del noroeste de la Península Ibérica, se constató la relación directa entre esta forma de alteración y la presencia de sulfato de calcio y se propuso el mecanismo a través del cual esta sal provoca este tipo de deterioro. En este trabajo se plantean varias hipótesis acerca del origen del yeso encontrado en monumentos graníticos. Para ello se comparan los contenidos de iones solubilizados en agua, los resultados de difracción de rayos X y las relaciones OCa/SO3 de muestras de piedra, morteros y depósitos recogidas en diferentes monumentos. Se llega a la conclusión de que en la mayor parte de los casos el yeso procede de antiguas pinturas o de revestimientos superficiales y de los morteros de juntas entre sillares, pero no se puede descartar la contribución de otros aportes, los cuales se discuten también en este artículo.

  20. Rehabilitation of gypsum-mined lands in the Indian desert

    Sharma, K.D.; Kumar, S.; Gough, L.P.


    The economic importance of mining in the Indian Desert is second only to agriculture. Land disturbed by mining, however, has only recently been the focus of rehabilitation efforts. This research assesses the success of rehabilitation plans used to revegetate gypsum mine spoils within the environmental constraints of the north-west Indian hot-desert ecosystem. The rehabilitation plan first examined both mined and unmined areas and established assessments of existing vegetative cover and the quality of native soils and mine spoils. Tests were made on the effect of the use, and conservation, of available water through rainwater harvesting, amendment application (for physical and chemical spoil modification), plant establishment protocols, and the selection of appropriate germ plasm. Our results show that the resulting vegetative cover is capable of perpetuating itself under natural conditions while concurrently meeting the needs of farmers. Although the mine spoils are deficient in organic matter and phosphorus, they possess adequate amounts of all other nutrients. Total boron concentrations (>5.0 mg kg-1) in both the topsail and mine spoil indicate potentially phytotoxic conditions. Electrical conductance of mine spoil is 6-10 times higher than for topsail with a near-neutral pH. Populations of spoil fungi, Azotobactor, and nitrifying bacteria are low. The soil moisture storage in rainwater harvesting plots increased by 8% over the control and 48% over the unmined area. As a result of rehabilitation efforts, mine spoils show a steady buildup in organic carbon, and P and K due to the decomposition of farmyard manure and the contribution of nitrogen fixation by the established leguminous plant species. The rehabilitation protocol used at the site appears to have been successful. Following revegetation of the area with a mixture of trees, shrubs, and grasses, native implanted species have become established. Species diversity, measured in terms of species richness

  1. Design of Cold-Formed Steel Screw Connections with Gypsum Sheathing at Ambient and Elevated Temperatures

    Wei Chen


    Full Text Available Load-bearing cold-formed steel (CFS walls sheathed with double layers of gypsum plasterboard on both sides have demonstrated good fire resistance and attracted increasing interest for use in mid-rise CFS structures. As the main connection method, screw connections between CFS and gypsum sheathing play an important role in both the structural design and fire resistance of this wall system. However, studies on the mechanical behavior of screw connections with double-layer gypsum sheathing are still limited. In this study, 200 monotonic tests of screw connections with single- or double-layer gypsum sheathing at both ambient and elevated temperatures were conducted. The failure of screw connections with double-layer gypsum sheathing in shear was different from that of single-layer gypsum sheathing connections at ambient temperature, and it could be described as the breaking of the loaded sheathing edge combined with significant screw tilting and the loaded sheathing edge flexing fracture. However, the screw tilting and flexing fracture of the loaded sheathing edge gradually disappear at elevated temperatures. In addition, the influence of the loaded edge distance, double-layer sheathing and elevated temperatures is discussed in detail with clear conclusions. A unified design formula for the shear strength of screw connections with gypsum sheathing is proposed for ambient and elevated temperatures with adequate accuracy. A simplified load–displacement model with the post-peak branch is developed to evaluate the load–displacement response of screw connections with gypsum sheathing at ambient and elevated temperatures.

  2. Utilization Alternatives and Potentiality for FGD Gypsum from Coal-Fired Power Plants

    Tian Hezhong; Hao Jiming; Zhao Zhe; Kong Xiangying; Yang Chao; Lu Guangjie; Liu Hanqiang; Xu Fenggang; Chu Xue


    @@ It is estimated that an installed capacity of thermal power units with desulphurization equipment will come up to 40-50 GW by the end of 2020, which affords a good opportunity for opening up and development of the market of the by-product gypsum from thermal power desulphurization. Therefore, it is necessary to research the present situation and restrictive factors in the comprehensive utilization of FGD gypsum.

  3. Authigenic gypsum found in gas hydrate-associated sediments from Hydrate Ridge, the eastern North Pacific

    WANG; Jiasheng; Erwin; Suess; Dirk; Rickert


    Characteristic gypsum micro-sphere and granular mass were discovered by binocular microscope in the gas hydrate-associated sediments at cores SO143-221 and SO143/TVG40-2A respectively on Hydrate Ridge of Cascadia margin, the eastern North Pacific. XRD patterns and EPA analyses show both micro-sphere and granular mass of the crystals have the typical peaks and the typical main chemical compositions of gypsum, although their weight percents are slightly less than the others in the non-gas hydrate-associated marine regions. SEM pictures show that the gypsum crystals have clear crystal boundaries, planes, edges and cleavages of gypsum in form either of single crystal or of twin crystals. In view of the fact that there are meanwhile gas hydrate-associated authigenic carbonates and SO42(-rich pore water in the same sediment cores, it could be inferred reasonably that the gypsums formed also authigenically in the gas hydrate-associated environment too, most probably at the interface between the downward advecting sulfate-rich seawater and the below gas hydrate, which spilled calcium during its formation on Hydrate Ridge. The two distinct forms of crystal intergrowth, which are the granular mass of series single gypsum crystals at core SO143/TVG40-2A and the microsphere of gypsum crystals accompanied with detrital components at core SO143-221 respectively, indicate that they precipitated most likely in different interstitial water dynamic environments. So, the distinct authigenic gypsums found in gas hydrate-associated sediments on Hydrate Ridge could also be believed as one of the parameters which could be used to indicate the presence of gas hydrate in an unknown marine sediment cores.

  4. Research of gypsum binder of phosphogypsum and dry mortar on its basis

    Казимагомедов, Ибрагим Эмирчубанович; Дехтярюк, Ольга Игоревна


    Gypsum binder was received by the method of intensive dehydration and the influence of admixture in phosphogypsum on the hydration process of gypsum binder was researched. Phase composition of phosphogypsum before and after calcination, using XFA, IR-spectroscopy and crystal optic analysis was defined. Dry mortar for plaster of interior walls of buildings on the basis of CaSO4·0,5H2O obtained from phosphogypsum is investigated. Its advantages and physical and chemical characteristics are shown


    Pustovgar Andrey Petrovich


    Full Text Available The authors considered the gypsum binder obtained in a kettle SMA-158A in the enterprise LLC “MaykopGipsStroy”. The initial gypsum binder burnt at a temperature of 120 °Сwith the following unloading out of the kettle possessed unstable physical, mechanical and operational characteristics, that’s why the grade of gypsum binder was changed from G4-AII to G5-BII for different lots, which greatly reduced its application in the composition of dry mortars. It was stated, that instability of the features of gypsum binder is determined by the essential underburning of the system, which was characterized by residual content of calcium sulfate dihydrate in amount from 2 to 7 % by weight. In frames of the investigation the authors succeeded in raising the grade of the produced gypsum binder (from G4-5 to G6 due to optimization of the technological parameters of the burning process, as well as to stabilize the composition and features, to lay down temperature and time parameters allowing to control the technological process in order to obtain the gypsum binder with specified characteristics.

  6. Estimating gypsum equirement under no-till based on machine learning technique

    Alaine Margarete Guimarães

    Full Text Available Chemical stratification occurs under no-till systems, including pH, considering that higher levels are formed from the soil surface towards the deeper layers. The subsoil acidity is a limiting factor of the yield. Gypsum has been suggested when subsoil acidity limits the crops root growth, i.e., when the calcium (Ca level is low and/or the aluminum (Al level is toxic in the subsoil layers. However, there are doubts about the more efficient methods to estimate the gypsum requirement. This study was carried out to develop numerical models to estimate the gypsum requirement in soils under no-till system by the use of Machine Learning techniques. Computational analyses of the dataset were made applying the M5'Rules algorithm, based on regression models. The dataset comprised of soil chemical properties collected from experiments under no-till that received gypsum rates on the soil surface, throughout eight years after the application, in Southern Brazil. The results showed that the numerical models generated by rule induction M5'Rules algorithm were positively useful contributing for estimate the gypsum requirements under no-till. The models showed that Ca saturation in the effective cation exchange capacity (ECEC was a more important attribute than Al saturation to estimate gypsum requirement in no-till soils.

  7. Room-temperature electrolytic coloration and spectral properties of natural fibrous gypsum using a pointed anode

    Gu, Hongen, E-mail:; Hao, Xiaoqing; Tian, Pin


    Electrolysis experiments can be performed at room temperature and under various voltages using natural fibrous (NF) gypsum with a pointed anode and a flat cathode. The NF gypsum is colored electrolytically. SO{sub 4}{sup −}, SO{sub 3}{sup −}, SO{sub 2}{sup −}, O{sub 3}{sup −} and O{sup −} defect centers are produced in colored NF gypsum. The characteristic absorption bands of the defect centers are observed in the absorption spectra of the colored NF gypsum. The defect centers come mainly from electric-field-induced decomposition and/or direct electron loss of SO{sub 4}{sup 2−} radicals. Current is measured during electrolytic coloration. Electron exchanges from electron and charged radicals to electrodes induce complete current. -- Highlights: • We expanded the traditional electrolysis method. • Electrolysis experiments are performed at room temperature for the first time. • Natural fibrous gypsum is colored electrolytically. • SO{sub 4}{sup −}, SO{sub 3}{sup −}, SO{sub 2}{sup −}, O{sub 3}{sup −} and O{sup −} defect centers are produced in colored gypsum. • Defect centers come from electron transfers and decomposition of SO{sub 4}{sup 2−} radicals.

  8. Oxidation of North Dakota scrubber sludge for soil amendment and production of gypsum. Final report

    Hassett, D.J.; Moe, T.A.


    Cooperative Power`s Coal Creek Station (CCS) the North Dakota Industrial Commission, and the US Department of Energy provided funds for a research project at the Energy and Environmental Research Center. The goals of the project were (1) to determine conditions for the conversion of scrubber sludge to gypsum simulating an ex situ process on the laboratory scale; (2) to determine the feasibility of scaleup of the process; (3) if warranted, to demonstrate the ex situ process for conversion on the pilot scale; and (4) to evaluate the quality and handling characteristics of the gypsum produced on the pilot scale. The process development and demonstration phases of this project were successfully completed focusing on ex situ oxidation using air at low pH. The potential to produce a high-purity gypsum on a commercial scale is excellent. The results of this project demonstrate the feasibility of converting CCS scrubber sludge to gypsum exhibiting characteristics appropriate for agricultural application as soil amendment as well as for use in gypsum wallboard production. Gypsum of a purity of over 98% containing acceptable levels of potentially problematic constituents was produced in the laboratory and in a pilot-scale demonstration.

  9. Petrography of gypsum-bearing facies of the Codó Formation (Late Aptian, Northern Brazil

    Jackson D.S. Paz


    Full Text Available An original and detailed study focusing the petrography of evaporites from the Late Aptian deposits exposed in the eastern and southern São Luís-Grajaú Basin is presented herein, with the attempt of distinguishing between primary and secondary evaporites, and reconstructing their post-depositional evolution. Seven evaporites phases were recognized: 1. chevron gypsum; 2. nodular to lensoidal gypsum or anhydrite; 3. fibrous to acicular gypsum; 4. mosaic gypsum; 5. brecciated gypsum or gypsarenite; 6. pseudo-nodular anhydrite or gypsum; and 7. rosettes of gypsum. The three first phases of gypsum display petrographic characteristics that conform to a primary nature. The fibrous to acicular and mosaic gypsum were formed by replacement of primary gypsum, but their origin took place during the eodiagenesis, still under influence of the depositional setting. These gypsum morphologies are closely related to the laminated evaporites, serving to demonstrate that their formation was related to replacements that did not affect the primary sedimentary structures. The pseudo-nodular anhydrite or gypsum seems to have originated by mobilization of sulfate-rich fluids during burial, probably related to halokinesis. The rosettes of gypsum, which intercept all the other gypsum varieties, represent the latest phase of evaporite formation in the study area, resulting from either intrastratal waters or surface waters during weathering.Neste trabalho, é apresentado um estudo original e detalhado enfocando os aspectos petrográficos dos evaporitos de depósitos aptianos superiores expostos no sul e leste da Bacia de São Luís-Grajaú. O objetivo é o estabelecimento de critérios que permitam distinguir entre evaporitos primários e secundários, além da reconstrução de sua evolução pós-deposicional. Sete fases de evaporitos foram reconhecidas: 1. gipsita em chevron; 2. gipsita ou anidrita nodular a lenticular; 3. gipsita fibrosa a acicular; 4. gipsita em

  10. Properties of mortars made by uncalcined FGD gypsum-fly ash-ground granulated blast furnace slag composite binder.

    Zhong, Shiyun; Ni, Kun; Li, Jinmei


    A series of novel mortars were developed from composite binder of uncalcined FGD gypsum, fly ash (FA) and ground granulated blast furnace slag (GGBFS) for the good utilization of flue gas desulphurization (FGD) gypsum. At a fixed ratio (20%) of GGBFS to the composite binder, keeping consistency of the mortar between 9.5 and 10.0 cm, the properties of the composite mortar were studied. The results show that higher water/binder (W/B) is required to keep the consistency when increasing the percentage of FGD gypsum. No obvious influences of the W/B and content of FGD gypsum on the bleeding of paste were observed which keeps lower than 2% under all experimental conditions tried. The highest compressive and flexural strengths (ratio is 20% FGD gypsum, 20% GGBFS and 60% FA) are 22.6 and 4.3 MPa at 28 days, respectively. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results indicate that massive ettringite crystals and C-S-H gels exist in the hydration products. At 90 days the mortars with FGD gypsum is dramatically smaller drying shrinkage (563-938 micro strain) than that without FGD gypsum (about 2250 micro strain). The release of the SO(4)(2-) from the mortar was analyzed, indicating that the dissolution of sulfate increases with FGD gypsum. The concentration of SO(4)(2-) releasing from the mortar with 10% FGD gypsum is almost equal to that obtained from the mortar without FGD gypsum. The release of SO(4)(2-) from the mortar with 20% FGD gypsum is 9200 mg·m(-2), which is lower than that from the mortar with 95% cement clinker and 5% FGD gypsum.

  11. Influence of different levels of gypsum on growth, herb and essential oil yields of lemongrass

    Pandu Sastry Kakaraparthi


    Full Text Available The essential oil obtained from lemongrass (Cymbopogon flexuosus is an industrially important essential oil being used widely for the isolation of citral which can be converted into ionones. Improving the economic yield of the aromatic grass lemongrass is part of the rural development mandate of Central Institute of Medicinal and Aromatic Plants (CSIR-CIMAP. Salt affected soils occupy wide regions scattered all over the world and India has considerable salt-affected soils. The experiment was conducted on a red sandy loam soil at the research farm of CSIR-CIMAP, Hyderabad, India with five levels of gypsum as treatments(0-4 tons/ha.The soils of the experimental site are on the leeward side of an industrial area and the ground water has become saline due to industrial effluents. A field experiment was initiated to study the influence of gypsum in soil remediation and its influence on the growth and herb yield of lemongrass. Due to application of four tons of gypsum /ha a progressive decrease in the soil pH was observed and soil pH also decreased with advancement in time and it decreased from 7.73 to 7.40 at 120 days after planting due to gypsum application. EC increased progressively in all the treatments with time. The increase was less due to gypsum treatments. Similar trend was noticed in case of bicarbonate content of the soil and carbonates were absent in the soil. Gypsum application resulted in increased herb and essential oil yield of lemongrass due to better growth of plants(plant height, number of leaves /plant , number of tillers / clump and weight of plant / clump and the optimum dose of gypsum required is four tons/ha.

  12. Origin of zoning within dedolomite and calcitized gypsum of the Mississippian Arroyo Penasco Group

    Ulmer, D.S.


    The Mississippian Arroyo Penasco Group carbonates are the oldest Paleozoic rocks present in north-central New Mexico. These supratidal to shallow,subtidal sediments exhibit complex diagenetic fabrics produced by periods of pre-Pennsylvanian subaerial exposure. Both extensive recrystallization of the Espiritu Santo carbonates and brecciation of the overlying Macho Member of the Tererro Formation resulted from an extended period of Mississippian subaerial exposure of broad, low-relief tidal flats. Cathodoluminescent petrography indicates that the recrystallized limestones consist of calcite pseudomorphs of dolomite and gypsum. Dedolomite and calcitized gypsum crystals, with /sup 13/C//sup 12/C ratios of -2 to +1.5% PDB, range from highly zoned to uniformly luminescent. Electron microprobe analyses reveals variable Mn and Fe contents across the pseudomorphs which are responsible for differences in observed luminosity. These features are interpreted to reflect a period of subaerial exposure after deposition of Macho Member sediments, which caused dissolution of gypsum and dolomite by sulfate and Mg depleted meteoric fluids and produced the collapse breccia. Preservation of zoning within some pseudomorphs required simultaneous dissolution of gypsum and dolomite and precipitation of calcite. C-isotope data indicates a meteoric to mixed phreatic origin for pore fluids which precipitated calcite; repetitive zoning within dolomite and gypsum pseudomorphs is indicative of interactions between marine and meteoric phreatic fluids in the intertidal environment.

  13. The influence of composition of gypsum plaster on its technological properties

    M. Pawlak


    Full Text Available Gypsum plasters used in art and precision foundry always are the composition of gypsum-silica-cristobalite. It is necessary considering the specifity of plaster during heating stage. Plaster undergoes then, structural transformations causing significant variations of its volume which are nonuniform and proceed with different intensity. The content of silica and cristobalite reduces dimensional variations of setted gypsum plaster what increases dimensional accuracy and significant stresses reduction limiting the possibility of mould cracks occurrence during heating.The influence of cristobalite and silica addition on basic gypsum plaster properties like setting time, dimensional changes after setting, bending strength and permeability in raw and heat treated state are presented in this paper. Experiments were done for mixes containing 30÷70% of the gypsum. It was proven that cristobalite has the biggest influence on the bounding time and expansion of the sandmix and the strength and permeability do not depend on the type of additions and only on theirs total amount in the composition.

  14. Consolidation of archaeological gypsum plaster by bacterial biomineralization of calcium carbonate.

    Jroundi, Fadwa; Gonzalez-Muñoz, Maria Teresa; Garcia-Bueno, Ana; Rodriguez-Navarro, Carlos


    Gypsum plasterworks and decorative surfaces are easily degraded, especially when exposed to humidity, and thus they require protection and/or consolidation. However, the conservation of historical gypsum-based structural and decorative materials by conventional organic and inorganic consolidants shows limited efficacy. Here, a new method based on the bioconsolidation capacity of carbonatogenic bacteria inhabiting the material was assayed on historical gypsum plasters and compared with conventional consolidation treatments (ethyl silicate; methylacrylate-ethylmethacrylate copolymer and polyvinyl butyral). Conventional products do not reach in-depth consolidation, typically forming a thin impervious surface layer which blocks pores. In contrast, the bacterial treatment produces vaterite (CaCO3) biocement, which does not block pores and produces a good level of consolidation, both at the surface and in-depth, as shown by drilling resistance measurement system analyses. Transmission electron microscopy analyses show that bacterial vaterite cement formed via oriented aggregation of CaCO3 nanoparticles (∼20nm in size), resulting in mesocrystals which incorporate bacterial biopolymers. Such a biocomposite has superior mechanical properties, thus explaining the fact that drilling resistance of bioconsolidated gypsum plasters is within the range of inorganic calcite materials of equivalent porosity, despite the fact that the bacterial vaterite cement accounts for only a 0.02 solid volume fraction. Bacterial bioconsolidation is proposed for the effective consolidation of this type of material. The potential applications of bacterial calcium carbonate consolidation of gypsum biomaterials used as bone graft substitutes are discussed.

  15. Crack Coalescence in Molded Gypsum and Carrara Marble: Part 2—Microscopic Observations and Interpretation

    Wong, L. N. Y.; Einstein, H. H.


    Experimental uniaxial compression loading tests were conducted on molded gypsum and Carrara marble prismatic specimens to study the cracking and coalescence processes between pre-existing artificial flaws. The study showed that material had an influence on the cracking and coalescence processes (see the companion paper in this issue). As reported in the companion paper, one of the pronounced features as observed in the high-speed video recordings was the development of macroscopic white patches prior to the development of observable cracks in marble, but not in gypsum. This paper (part 2) deals with the microscopic aspects of the study. Specifically, the scanning electron microscope (SEM) and the environmental scanning electron microscope (ESEM) imaging techniques were used to study the microscopic development of white patches and their evolution into macroscopic tensile cracks and shear cracks in marble, and the microscopic initiation of hair-line tensile cracks and their evolution into macroscopic tensile cracks in gypsum. The microscopic imaging study in marble showed that the white patches were associated with extensive microcracking zones (process zones), while the extent of process zone development in gypsum was limited. The comparison of the macroscopic and microscopic results indicates that the different extent of microcracking zone development, related to the material textural properties, is a key factor leading to different macroscopic cracking behavior in gypsum and marble.

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

    Kirchheim, A. P.


    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.

  17. The effect of magnesium on partial sulphate removal from mine water as gypsum.

    Tolonen, Emma-Tuulia; Rämö, Jaakko; Lassi, Ulla


    The aim of this research was to investigate the effect of magnesium on the removal efficiency of sulphate as gypsum from mine water. The precipitation conditions were simulated with MINEQL + software and the simulation results were compared with the results from laboratory jar test experiments. Both the simulation and the laboratory results showed that magnesium in the mine water was maintaining sulphate in a soluble form as magnesium sulphate (MgSO4) at pH 9.6. Thus magnesium was preventing the removal of sulphate as gypsum (CaSO4·2H2O). However, change in the lime precipitation pH from 9.6 to 12.5 resulted in magnesium hydroxide (Mg(OH)2) precipitation and improved sulphate removal. Additionally, magnesium hydroxide could act as seed crystals for gypsum precipitation or co-precipitate sulphate further enhancing the removal of sulphate from mine water. Copyright © 2015 Elsevier Ltd. All rights reserved.


    CHUMAK Anastasia Gennadievna


    Full Text Available The aim of this work is to carry out a number of studies in the area of nanomodi­fication of gypsum binder matrix and to investigate the influence of multilayer carbon nanotubes on the structure, physical and mechanical properties of obtained compos­ites. The study of the gypsum binders structure formation mechanisms with the use of nanoadditives makes it possible to control the production processes of gypsum materi­als and articles with the given set of properties. The main tasks of the binder nanomodification are: even distribution of carbon nanostructures over the whole volume of material and provision of stability for the nanodimensional modifier during production process of the construction composite.

  19. Petroleum Sludge as gypsum replacement in cement plants: Its Impact on Cement Strength

    Benlamoudi, Ali; Kadir, Aeslina Abdul; Khodja, Mohamed


    Due to high cost of cement manufacturing and the huge amount of resources exhaustion, companies are trying to incorporate alternative raw materials or by-products into cement production so as to produce alternative sustainable cement. Petroleum sludge is a dangerous waste that poses serious imparts on soil and groundwater. Given that this sludge contains a high percentage of anhydrite (CaSO4), which is the main component of gypsum (CaSO4.2H2O), it may play the same gypsum role in strength development. In this research, a total replacement of gypsum (100%) has been substituted by petroleum sludge in cement production and has led to an increase of 28.8% in UCS values after 28 curing days. Nevertheless, the burning of this waste has emitted a considerable amount of carbon monoxide (CO) gas that needs to be carefully considered prior to use petroleum sludge within cement plants.

  20. Compartmentalization of gypsum and halite associated with cyanobacteria in saline soil crusts.

    Canfora, Loredana; Vendramin, Elisa; Vittori Antisari, Livia; Lo Papa, Giuseppe; Dazzi, Carmelo; Benedetti, Anna; Iavazzo, Pietro; Adamo, Paola; Jungblut, Anne D; Pinzari, Flavia


    The interface between biological and geochemical components in the surface crust of a saline soil was investigated using X-ray diffraction, and variable pressure scanning electron microscopy in combination with energy dispersive X-ray spectrometry. Mineral compounds such as halite and gypsum were identified crystallized around filaments of cyanobacteria. A total of 92 genera were identified from the bacterial community based on 16S gene pyrosequencing analysis. The occurrence of the gypsum crystals, their shapes and compartmentalization suggested that they separated NaCl from the immediate microenvironment of the cyanobacteria, and that some cyanobacteria and communities of sulfur bacteria may had a physical control over the distinctive halite and gypsum structures produced. This suggests that cyanobacteria might directly or indirectly promote the formation of a protective envelope made of calcium and sulfur-based compounds.

  1. LCA of Recycling Options for Gypsum from Construction and Demolition Waste

    Butera, Stefania; Møller, Jacob; Christensen, Thomas Højlund


    Large amounts of gypsum waste are annually produced from the construction and demolition sector. Its landfilling is becoming more and more expensive due to stricter EU regulations, while its recycling together with the rest of construction and demolition waste might be hampered due to technical...... restrictions; source separation, however, makes gypsum waste recycling feasible. Different alternatives for recycling exist, but their overall environmental impacts have never been quantified and compared in details. This study investigates from a life cycle perspective the environmental impacts of two...

  2. Gypsum addition to soils contaminated by red mud: implications for aluminium, arsenic, molybdenum and vanadium solubility.

    Lehoux, Alizée P; Lockwood, Cindy L; Mayes, William M; Stewart, Douglas I; Mortimer, Robert J G; Gruiz, Katalin; Burke, Ian T


    Red mud is highly alkaline (pH 13), saline and can contain elevated concentrations of several potentially toxic elements (e.g. Al, As, Mo and V). Release of up to 1 million m(3) of bauxite residue (red mud) suspension from the Ajka repository, western Hungary, caused large-scale contamination of downstream rivers and floodplains. There is now concern about the potential leaching of toxic metal(loid)s from the red mud as some have enhanced solubility at high pH. This study investigated the impact of red mud addition to three different Hungarian soils with respect to trace element solubility and soil geochemistry. The effectiveness of gypsum amendment for the rehabilitation of red mud-contaminated soils was also examined. Red mud addition to soils caused a pH increase, proportional to red mud addition, of up to 4 pH units (e.g. pH 7 → 11). Increasing red mud addition also led to significant increases in salinity, dissolved organic carbon and aqueous trace element concentrations. However, the response was highly soil specific and one of the soils tested buffered pH to around pH 8.5 even with the highest red mud loading tested (33 % w/w); experiments using this soil also had much lower aqueous Al, As and V concentrations. Gypsum addition to soil/red mud mixtures, even at relatively low concentrations (1 % w/w), was sufficient to buffer experimental pH to 7.5-8.5. This effect was attributed to the reaction of Ca(2+) supplied by the gypsum with OH(-) and carbonate from the red mud to precipitate calcite. The lowered pH enhanced trace element sorption and largely inhibited the release of Al, As and V. Mo concentrations, however, were largely unaffected by gypsum induced pH buffering due to the greater solubility of Mo (as molybdate) at circumneutral pH. Gypsum addition also leads to significantly higher porewater salinities, and column experiments demonstrated that this increase in total dissolved solids persisted even after 25 pore volume replacements. Gypsum

  3. Study on the Possibility of Using Vine Stalk Waste ( Vitis Vinifera) for Producing Gypsum Particleboards

    Rangavar, H.; Khosro, S. Kh.; Payan, M. H.; Soltani, A.


    The objective of this study was the production of gypsum particleboards with vine stalk waste and the investigation of some physical and mechanical properties of the boards. For this purpose, boards were made from gypsum, oven-dried mass of vine stalk waste, and the white portland cement in various ratios. The thickness swelling and water absorption after 2 and 24 hours of immersion in water, the modulus of rupture, the modulus of elasticity, and the internal bond strength of the boards were determined according to the European Norms standard. The results show that, by selecting proper ratios between the constituents, particleboards with good physicomechanical properties can be produced.

  4. Building on previous OSL dating techniques for gypsum: a case study from Salt Basin playa, New Mexico and Texas

    Mahan, Shannon; Kay, John


    The long term stability and reliability of the luminescence signal for gypsum has not been well documented or systematically measured until just recently. A review of the current literature for luminescence dating of gypsum is compiled here along with original efforts at dating an intact and in-situ bed of selenite gypsum at Salt Basin Playa, New Mexico and Texas. This effort differs from other documented luminescence dating efforts because the gypsum is not powdery or redistributed from its original growth patterns within the playa basin but is instead of a crystalline form. Sixteen ages from eight cores were ultimately produced with seven of the ages coming from rare detrital quartz encased in or with the gypsum crystals while the remaining ages are from the crystalline gypsum. As far as can be ascertained, the quartz was measured separately from the gypsum and no contaminants were noted in any of the aliquots. Some basic and preliminary tests of signal stability were measured and found to be mitigated by lessening of pre-heat protocols. Ages ranged from 8 ka to 10 ka in the shallow cores and 16 ka to 22 ka in the deeper cores. These ages will be useful in determining rates of gypsum growth within a sequence of evaporates which, in turn, will help to better document historic rates of evaporation and thus estimate, with more precision, the corresponding annual evaporation rates.

  5. Evaluation of Synthetic Gypsum Recovered via Wet Flue-Gas Desulfurization from Electric Power Plants for Use in Foundries

    R. Biernacki


    Full Text Available This article investigates possible use of waste gypsum (synthetic, recovered via flue-gas desulfurization from coal-fired electric powerplants, in foundries. Energy sector, which in Eastern Europe is mostly composed from coal-fired electric power plants, is one of the largestproducers of sulfur dioxide (SO2.In order to protect the environment and reduce the amount of pollution flue-gas desulfurization (FGD is used to remove SO2 fromexhaust flue gases of fossil-fuel power plants. As a result of this process gypsum waste is produced that can be used in practicalapplications.Strength and permeability tests have been made and also in-depth analysis of energy consumption of production process to investigateways of preparing the synthetic gypsum for casting moulds application. This paper also assesses the chemical composition, strength andpermeability of moulds made with synthetic gypsum, in comparison with moulds made with traditional GoldStar XL gypsum and withceramic molds. Moreover examination of structure of synthetic gypsum, the investigations on derivatograph and calculations of energyconsumption during production process of synthetic gypsum in wet flue-gas desulfurization were made.After analysis of gathered data it’s possible to conclude that synthetic gypsum can be used as a material for casting mould. There is nosignificant decrease in key properties, and on the other hand there is many additional benefits including low energy consumption,decreased cost, and decreased environmental impact.

  6. Sulfate specifications as a constraint to gypsum addition to cement and possible replacement of gypsum as an additive. Quarterly technical progress report, June-August 1979

    Kantro, D.L.


    Potential alternatives to gypsum for controlling set in commercial cement, additives to deter sulfate-induced expansion, and the influence of clinker manufacture on expansion potential in cements were studied. If limitations on sulfate content were less restrictive, it would be possible to use kiln fuels with higher sulfur contents, and to employ energy efficient preheater kiln technology without risk of exceeding sulfate specifications. (FS)

  7. The Aspects About of Objectively Appraisals of Modeling Gypsum Quality and Composites of Phonic-Absorbent and Orthopedic on Base of Gypsum

    Pop, P. A.; Ungur, P. A.; Lazar, L.; Marcu, F.


    The EU Norms about of protection environment, outside and inside ambient, and human health demands has lead at obtain of new materials on the base of airborne material, with high thermo and phonic-absorbent properties, porous and lightweight. The α and β-modeling gypsum plaster quality and lightweight depend on many factors as: fabrication process, granulation, roast temperature, work temperature, environment, additives used, breakage, etc. Also, the objectively appraisal of modeling gypsum quality depends of proper tests methods selection, which are legislated in norms, standards and recommendations. In Romanian Standards SR EN 13279-1/2005 and SR EN 13279-2/2005, adaptable from EU Norms EN 13279-1/2004 and EN 13279-2/2004, the characteristics gypsum family tests are well specification, as: granule-metric analysis, determination of water/plaster ratio, setting time, mechanical characteristics, adhesions and water restrain. For plaster with special use (phonic-absorbent and orthopedic materials, etc.) these determinations are not concluding, being necessary more parameters finding, as: elastic constant, phonic-absorbent coefficient, porosity, working, etc., which is imposed the completion of norms and standards with new determinations.

  8. Hydrothermal synthesis of calcium sulfate whisker from flue gas desulfurization gypsum

    Chengjun Liu; Qing Zhao; Yeguang Wang; Peiyang Shi; Maofa Jiang


    Plenty of flue gas desulfurization (FGD) gypsum generated from coal-fired power plants for sulfur dioxide se-questration caused many environmental issues. Preparing calcium sulfate whisker (CSW) from FGD gypsum by hydrothermal synthesis is considered to be a promising approach to solve this troublesome problem and uti-lize calcium sulfate in a high-value-added way. The effects of particle size of FGD gypsum, slurry concentration, and additives on CSW were investigated in this work. The results indicated that fine particle size of FGD gypsum and moderately high slurry concentration were beneficial for crystal nucleation and growth. Three additives of magnesium chloride, citric acid, and sodium dodecyl benzene sulfonate (SDBS) were employed in this study. It was found that mean length and aspect ratio of CSW were both decreased by the usage of magnesium chloride, while a small quantity of citric acid or SDBS could improve the CSW morphology. When multi-additives of citric acid-SDBS were employed, the mean length and aspect ratio increased more than 20%. Moreover, surface morphology of CSW went better, and the particle size and crystal shape became more uniform.

  9. Morphology and stability of aggregates of an Oxisol according to tillage system and gypsum application

    Fábio Régis de Souza


    Full Text Available Morphological characterization and aggregate stability is an important factor in evaluating management systems. The aim of this paper is to evaluate the stability and morphology of the aggregates of a dystrophic Oxisol managed with no-tillage and conventional tillage with and without the residual action of gypsum. The experimental design was randomized blocks arranged in split-split plot, where the treatments were two soil management systems (plots with 0 and 2000 kg ha-1 of gypsum (subplots and five depths (0-0.05, 0.05-0.10, 0.10-0.15, 0.15-0.20 and 0.20-0.30 m as the subsubplots, with four replications. The aggregate morphology was determined through images and later evaluated by the Quantporo software. Stability was determined by the wet method. The results showed that the no-tillage system, with or without gypsum residual effect, provided the aggregates with the largest geometric diameters. The combination of no-tillage system and the gypsum residual effect provided rougher aggregates.

  10. Responses to Environmental Stress in Plants Adapted to Mediterranean Gypsum Habitats

    Josep V. LLINARES


    Full Text Available Gypsum areas are stressful environments inhabited by gypsophytes, plants that are exclusive for such habitats, and by plants that grow on gypsum but also on other soil types, the so-called gypsovags. To investigate possible differences between gypsovags and gypsophytes with respect to basic stress response mechanisms, two common osmolytes, glycine betaine and total soluble sugars, as well as monovalent (Na+ and K+ and bivalent (Ca2+ and Mg2+ cations, were quantified, under field conditions, in two Iberian endemic gypsophytes (Gypsophila struthium subsp. hispanica and Ononis tridentata and two common Mediterranean gypsovags (Rosmarinus officinalis and Helianthemum syriacum. Their spatial variation according to a topographic gradient and their temporal variation over a period of three successive seasons were correlated with climatic data and soil characteristics. This analysis confirmed that water stress is the main environmental stress factor in gypsum habitats, whereas the percentage of gypsum in the soil does not seem to play any relevant role in the activation of stress responses in plants. Glycine betaine may contribute to stress tolerance in the gypsophytes, but not in the gypsovags, according to the close correlation found between the level of this osmolyte and the gypsophily of the investigated taxa. Cation contents in the plants did not correlate with those present in the soil, but the gypsophytes have higher levels of Ca2+ and Mg2+ than the gypsovags, under all environmental conditions, which may represent an adaptation mechanism to their specific habitat.

  11. Gypsum plasterboards enhanced with phase change materials: A fire safety assessment using experimental and computational techniques

    Kolaitis Dionysios I.


    Full Text Available Phase Change Materials (PCM can be used for thermal energy storage, aiming to enhance building energy efficiency. Recently, gypsum plasterboards with incorporated paraffin-based PCM blends have become commercially available. In the high temperature environment developed during a fire, the paraffins, which exhibit relatively low boiling points, may evaporate and, escaping through the gypsum plasterboard's porous structure, emerge to the fire region, where they may ignite, thus adversely affecting the fire resistance characteristics of the building. Aiming to assess the fire safety behaviour of such building materials, an extensive experimental and computational analysis is performed. The fire behaviour and the main thermo-physical physical properties of PCM-enhanced gypsum plasterboards are investigated, using a variety of standard tests and devices (Scanning Electron Microscopy, Thermo Gravimetric Analysis, Cone Calorimeter. The obtained results are used to develop a dedicated numerical model, which is implemented in a CFD code. CFD simulations are validated using measurements obtained in a cone calorimeter. In addition, the CFD code is used to simulate an ISO 9705 room exposed to fire conditions, demonstrating that PCM addition may indeed adversely affect the fire safety of a gypsum plasterboard clad building.

  12. Palaeoclimatic significance of gypsum pseudomorphs in the inner shelf sediments off Machalipatnam bay

    Rao, V.P.

    Pseudo-gypsum crystals have been found in the coarse fraction of the sediments from the inner continental shelf off Machilipatnam Bay. They range in size from 3 to 7 mm are elongate and lenticular in shape. Bassanite and calcite are pseudomorphs...

  13. Composting and gypsum amendment of broiler litter to reduce nutrient leaching loss

    Relative to fresh broiler litter, little is known about the dynamics of composted litter derived-nutrient in the ecosystem. In this study, the potential leaching losses of nutrients from compost relative to fresh broiler litter along with flue gas desulfurization (FGD gypsum), as a nutrient immobil...

  14. Study of Fresh and Hardening Process Properties of Gypsum with Three Different PCM Inclusion Methods

    Susana Serrano


    Full Text Available Gypsum has two important states (fresh and hardened states, and the addition of phase change materials (PCM can vary the properties of the material. Many authors have extensively studied properties in the hardened state; however, the variation of fresh state properties due to the addition of Micronal® DS 5001 X PCM into gypsum has been the object of few investigations. Properties in fresh state define the workability, setting time, adherence and shrinkage, and, therefore the possibility of implementing the material in building walls. The aim of the study is to analyze, compare and evaluate the variability of fresh state properties after the inclusion of 10% PCM. PCM are added into a common gypsum matrix by three different methods: adding microencapsulated PCM, making a suspension of PCM/water, and incorporating PCM through a vacuum impregnation method. Results demonstrate that the inclusion of PCM change completely the water required by the gypsum to achieve good workability, especially the formulation containing Micronal® DS 5001 X: the water required is higher, the retraction is lower (50% less due to the organic nature of the PCM with high elasticity and, the adherence is reduced (up to 45% due to the difference between the porosity of the different surfaces as well as the surface tension difference.

  15. Investigation of Parameters Affecting Gypsum Dewatering Properties in a Wet Flue Gas Desulphurization Pilot Plant

    Hansen, Brian Brun; Kiil, Søren


    Wet flue gas desulphurization (FGD) plants with forced oxidation, installed at coal and oil fired power plants for removal of SO2(g), must produce gypsum of high quality. However, quality issues such as an excessive moisture content, due to poor gypsum dewatering properties, may occur from time...... to time. In this work, the particle size distribution, morphology, and filtration rate of wet FGD gypsum formed in a pilot-scale experimental setup, operated in forced oxidation mode, have been studied. The influence of holding tank residence time (10–408 h), solids content (30–169 g/L), and the presence...... of impurities (0.002 M Al2F6; 50 g quartz/L; 0.02 M Al3+, and 0.040 M Mg2+) were investigated. In addition, slurry from a full-scale wet FGD plant, experiencing formation of flat shaped crystals and poor gypsum dewatering properties, was transferred to the pilot plant to test if the plant would now start...

  16. Crack Coalescence in Molded Gypsum and Carrara Marble: Part 1. Macroscopic Observations and Interpretation

    Wong, L. N. Y.; Einstein, H. H.


    Cracking and coalescence behavior has been studied experimentally with prismatic laboratory-molded gypsum and Carrara marble specimens containing two parallel pre-existing open flaws. This was done at both the macroscopic and the microscopic scales, and the results are presented in two separate papers. This paper (the first of two) summarizes the macroscopic experimental results and investigates the influence of the different flaw geometries and material, on the cracking processes. In the companion paper (also in this issue), most of the macroscopic deformation and cracking processes shown in this present paper will be related to the underlying microscopic changes. In the present study, a high speed video system was used, which allowed us to precisely observe the cracking mechanisms. Nine crack coalescence categories with different crack types and trajectories were identified. The flaw inclination angle ( β), the ligament length ( L), that is, intact rock length between the flaws, and the bridging angle ( α), that is, the inclination of a line linking up the inner flaw tips, between two flaws, had different effects on the coalescence patterns. One of the pronounced differences observed between marble and gypsum during the compression loading test was the development of macroscopic white patches prior to the initiation of macroscopic cracks in marble, but not in gypsum. Comparing the cracking and coalescence behaviors in the two tested materials, tensile cracking generally occurred more often in marble than in gypsum for the same flaw pair geometries.

  17. The Thermal Damage Properties of Mudstone, Gypsum and Rock Salt from Yingcheng, Hubei, China

    Jie Chen


    Full Text Available The impacts of temperature on the surface thermal damage of rock salt, gypsum and mudstone from the Yingcheng salt mine, China were investigated by the surface crack growth and propagation tests at different temperatures. We found that: (a high temperature could strengthen the rock salt molecular thermal motion and weaken the cohesion among the rock salt grains, so that the grain boundaries were more prone to slip and thus develop into cracks; (b high temperature could make the water molecules evaporate from rock specimens, which should change the physical properties of gypsum and mudstone; and (c high temperature had a significant effect on the interface between rock salt and gypsum and mudstone, therefore it should be easy to produce cracks with white or light yellow cumulate powder here. The surface crack growth and propagation of the rock salt, gypsum and mudstone have a positive correlation with the temperature by stereo microscope and the method of binary images, which could observe the surface thermal damage properties. Finally, the fractal dimension of the rock salt surface cracks was calculated based on fractal theory, and the evolution of the surface thermal damage was found from 50 to 260 °C.

  18. 40 CFR 436.50 - Applicability; description of the gypsum subcategory.


    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Applicability; description of the gypsum subcategory. 436.50 Section 436.50 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS MINERAL MINING AND PROCESSING POINT SOURCE CATEGORY...

  19. Decreasing phosphorus loss in tile-drained landscapes using flue gas desulfurization gypsum

    Elevated phosphorus (P) loading from agricultural non-point source pollution continues to impair inland waterbodies throughout the world. The application of flue gas desulfurization (FGD) gypsum to agricultural fields has been suggested to decrease P loading because of its high calcium content and P...

  20. Assessment of Mercury in Soils, Crops, Earthworms, and Water when Soil is Treated with Gypsum

    Flue gas desulfurization (FGD) gypsum from fossil fuel combustion has many potential uses in agriculture, but there is concern about the potential environmental effects of its elevated mercury (Hg) concentration. The wet limestone scrubbing process that removes sulfur from flue gas (and produces gyp...

  1. Modeling grain size variations of aeolian gypsum deposits at White Sands, New Mexico, using AVIRIS imagery

    Ghrefat, H.A.; Goodell, P.C.; Hubbard, B.E.; Langford, R.P.; Aldouri, R.E.


    Visible and Near-Infrared (VNIR) through Short Wavelength Infrared (SWIR) (0.4-2.5????m) AVIRIS data, along with laboratory spectral measurements and analyses of field samples, were used to characterize grain size variations in aeolian gypsum deposits across barchan-transverse, parabolic, and barchan dunes at White Sands, New Mexico, USA. All field samples contained a mineralogy of ?????100% gypsum. In order to document grain size variations at White Sands, surficial gypsum samples were collected along three Transects parallel to the prevailing downwind direction. Grain size analyses were carried out on the samples by sieving them into seven size fractions ranging from 45 to 621????m, which were subjected to spectral measurements. Absorption band depths of the size fractions were determined after applying an automated continuum-removal procedure to each spectrum. Then, the relationship between absorption band depth and gypsum size fraction was established using a linear regression. Three software processing steps were carried out to measure the grain size variations of gypsum in the Dune Area using AVIRIS data. AVIRIS mapping results, field work and laboratory analysis all show that the interdune areas have lower absorption band depth values and consist of finer grained gypsum deposits. In contrast, the dune crest areas have higher absorption band depth values and consist of coarser grained gypsum deposits. Based on laboratory estimates, a representative barchan-transverse dune (Transect 1) has a mean grain size of 1.16 ??{symbol} (449????m). The error bar results show that the error ranges from - 50 to + 50????m. Mean grain size for a representative parabolic dune (Transect 2) is 1.51 ??{symbol} (352????m), and 1.52 ??{symbol} (347????m) for a representative barchan dune (Transect 3). T-test results confirm that there are differences in the grain size distributions between barchan and parabolic dunes and between interdune and dune crest areas. The t-test results

  2. Investigation on the Permeability Evolution of Gypsum Interlayer Under High Temperature and Triaxial Pressure

    Tao, Meng; Yechao, You; Jie, Chen; Yaoqing, Hu


    The permeability of the surrounding rock is a critical parameter for the designing and assessment of radioactive waste disposal repositories in the rock salt. Generally, in the locations that are chosen for radioactive waste storage, the bedded rock salt is a sedimentary rock that contains NaCl and Na2SO4. Most likely, there are also layers of gypsum ( {CaSO}_{ 4} \\cdot 2 {H}_{ 2} {O)} present in the salt deposit. Radioactive wastes emit a large amount of heat and hydrogen during the process of disposal, which may result in thermal damage of the surrounding rocks and cause a great change in their permeability and tightness. Therefore, it is necessary to investigate the permeability evolution of the gypsum interlayer under high temperature and high pressure in order to evaluate the tightness and security of the nuclear waste repositories in bedded rock salt. In this study, a self-designed rock triaxial testing system by which high temperature and pressure can be applied is used; the μCT225kVFCB micro-CT system is also employed to investigate the permeability and microstructure of gypsum specimens under a constant hydrostatic pressure of 25 MPa, an increasing temperature (ranging from 20 to 650 °C), and a variable inlet gas pressure (1, 2, 4, 6 MPa). The experimental results show: (a) the maximum permeability measured during the whole experiment is less than 10-17 m2, which indicates that the gypsum interlayer has low permeability under high temperature and pressure that meet the requirements for radioactive waste repository. (b) Under the same temperature, the permeability of the gypsum specimen decreases at the beginning and then increases as the pore pressure elevates. When the inlet gas pressure is between 0 and 2 MPa, the Klinkenberg effect is very pronounced. Then, as the pore pressure increases, the movement behavior of gas molecules gradually changes from free motion to forced directional motion. So the role of free movement of gas molecules gradually

  3. Can isotopic variations in structural water of gypsum reveal paleoclimatic changes?

    Gatti, E.; Bustos, D.; Coleman, M. L.


    Water of crystallization in gypsum can be used as paleo-environmental proxy to study large scale climatic variability in arid areas. This is because changes in the isotopic composition of water of crystallization are due to isotopic variations in the mother brine from which the mineral precipitated, and the brine isotopic composition is linked to evaporation processes and humidity. This is particularly important when the salts are the only traces left of the original water, i.e. in modern arid areas. This study aims to prove that the 2-D/18-O compositions of the water of crystallization extracted from successive precipitates or even different growth zones of natural gypsum (CaSO4·H2O) can reconstruct the evaporation history and paleo-humidity of the source water basin. The method was tested in a laboratory experiment that evaporated CaSO4 brines under controlled temperature and humidity conditions. The brine was left to evaporate for five days at two different humidities (45 and 75 RH%); subsequently, brines and precipitated gypsum were sampled at 24 hour intervals. In this way we simulated zoned growth of gypsum. The samples were then analyzed for oxygen and hydrogen isotopic composition using a Thermo Scientific TC/EA with modified column, coupled to a MAT 253 Thermo Finnigan mass spectrometer at JPL. If preliminary results validate the novel hypothesis that changes in mineral composition can reveal details of paleo-environmental conditions the theory will be tested on natural gypsum collected from selected areas in White Sands National Monument, New Mexico. The study is currently ongoing but the full dataset will be presented at the conference.

  4. Contaminant mobility and carbon sequestration downstream of the Ajka (Hungary) red mud spill: The effects of gypsum dosing.

    Renforth, P; Mayes, W M; Jarvis, A P; Burke, I T; Manning, D A C; Gruiz, K


    A number of emergency pollution management measures were enacted after the accidental release of caustic bauxite processing residue that occurred in Ajka, western Hungary in October, 2010. These centred on acid and gypsum dosing to reduce pH and minimise mobility of oxyanion contaminants mobile at high pH. This study assessed the effectiveness of gypsum dosing on contaminant mobility and carbon sequestration through assessment of red mud and gypsum-affected fluvial sediments via elemental analysis and stable isotope analysis. There was a modest uptake of contaminants (notably As, Cr, and Mn) on secondary carbonate-dominated deposits in reaches subjected to gypsum dosing. C and O stable isotope ratios of carbonate precipitates formed as a result of gypsum dosing were used to quantify the importance of the neutralisation process in sequestering atmospheric carbon dioxide. This process was particularly pronounced at sites most affected by gypsum addition, where up to 36% of carbonate-C appears to be derived from atmospheric in-gassing of CO(2). The site is discussed as a large scale analogue for potential remedial approaches and carbon sequestration technologies that could be applied to red mud slurries and other hyperalkaline wastes. The results of this work have substantial implications for the aluminium production industry in which 3-4% of the direct CO(2) emissions may be offset by carbonate precipitation. Furthermore, carbonation by gypsum addition may be important for contaminant remediation, also providing a physical stabilisation strategy for the numerous historic stockpiles of red mud.

  5. Formation mechanism of authigenic gypsum in marine methane hydrate settings: Evidence from the northern South China Sea

    Lin, Qi; Wang, Jiasheng; Algeo, Thomas J.; Su, Pibo; Hu, Gaowei


    During the last decade, gypsum has been discovered widely in marine methane hydrate-bearing sediments. However, whether this gypsum is an in-situ authigenic precipitate remains controversial. The GMGS2 expedition carried out in 2013 by the Guangzhou Marine Geological Survey (GMGS) in the northern South China Sea provided an excellent opportunity for investigating the formation of authigenic minerals and, in particular, the relationship between gypsum and methane hydrate. In this contribution, we analyzed the morphology and sulfur isotope composition of gypsum and authigenic pyrite as well as the carbon and oxygen isotopic compositions of authigenic carbonate in a drillcore from Site GMGS2-08. These methane-derived carbonates have characteristic carbon and oxygen isotopic compositions (δ13C: -57.9‰ to -27.3‰ VPDB; δ18O: +1.0‰ to +3.8‰ VPDB) related to upward seepage of methane following dissociation of underlying methane hydrates since the Late Pleistocene. Our data suggest that gypsum in the sulfate-methane transition zone (SMTZ) of this core precipitated as in-situ authigenic mineral. Based on its sulfur isotopic composition, the gypsum sulfur is a mixture of sulfate derived from seawater and from partial oxidation of authigenic pyrite. Porewater Ca2+ ions for authigenic gypsum were likely generated from carbonate dissolution through acidification produced by oxidation of authigenic pyrite and ion exclusion during methane hydrate formation. This study thus links the formation mechanism of authigenic gypsum with the oxidation of authigenic pyrite and evolution of underlying methane hydrates. These findings suggest that authigenic gypsum may be a useful proxy for recognition of SMTZs and methane hydrate zones in modern and ancient marine methane hydrate geo-systems.

  6. Soil fertility, nutrition and yield of maize and barley with gypsum application on soil surface in no-till

    Leandro Michalovicz


    Full Text Available Annual crop yield and nutrition have shown differentiated responses to modifications in soil chemical properties brought about by gypsum application. The aim of this study was to evaluate the effect of gypsum application rates on the chemical properties of a Latossolo Bruno (Clayey Oxisol, as well as on the nutrition and yield of a maize-barley succession under no-till. The experiment was set up in November 2009 in Guarapuava, Parana, Brazil, applying gypsum rates of 0.0, 1.5, 3.0, 4.5, and 6.0 Mg ha-1 to the soil surface upon sowing maize, with crop succession of barley. Gypsum application decreased the levels of Al3+ and Mg2+ in the 0.0-0.1 m layer and increased soil pH in the layers from 0.2-0.6 m depth. Gypsum application has increased the levels of Ca2+ in all soil layers up to 0.6 m, and the levels of S-SO4(2- up to 0.8 m. In both crops, the leaf concentrations of Ca and S were increased while Mg concentrations have decreased as a function of gypsum rates. There was also an effect of gypsum rates on grain yield, with a quadratic response of maize and a linear increase for barley. Yield increases were up to 11 and 12 % in relation to control for the maximum technical efficiency (MTE rates of 3.8 and 6.0 Mg ha-1 of gypsum, respectively. Gypsum application improved soil fertility in the profile, especially in the subsurface, as well as plant nutrition, increasing the yields of maize and barley.

  7. In Situ Observation of Gypsum-Anhydrite Transition at High Pressure and High Temperature

    LIU Chuan-Jiang; ZHENG Hai-Fei


    An in-situ Raman spectroscopic study of gypsum-anhydrite transition under a saturated water condition at high pressure and high temperature is performed using a hydrothermal diamond anvil cell (HDAC).The experimental results show that gypsum dissolvs in water at ambient temperature and above 496 MPa.With increasing temperature,the anhydrite (CaSO4) phase precipitates at 250 320℃ in the pressure range of 1.0 1.5 GPa,indicating that under a saturated water condition,both stable conditions of pressure and temperature and high levels of Ca and SO4 ion concentrations in aqueous solution are essential for the formation of anhydrite.A linear relationship between the pressure and temperature for the precipitation of anhydrite is established as P(GPa) =0.0068T - 0.7126 (250℃≤T≤320℃).Anhydrite remained stable during rapid cooling of the sample chamber,showing that the gypsum-anhydrite transition involving both dissolution and precipitation processes is irreversible at high pressure and high temperature.%An in-situ Raman spectroscopic study of gypsum-anhydrite transition under a saturated water condition at high pressure and high temperature is performed using a hydrothermal diamond anvil cell (HDAC). The experimental results show that gypsum dissolvs in water at ambient temperature and above 496 Mpa. With increasing temperature, the anhydrite (CaSO4) phase precipitates at 250-320℃ in the pressure range of 1.0-1.5 Gpa, indicating that under a saturated water condition, both stable conditions of pressure and temperature and high levels of Ca and SO4 ion concentrations in aqueous solution are essential for the formation of anhydrite. A linear relationship between the pressure and temperature for the precipitation of anhydrite is established as P(Gpa) = 0.0068T - 0.7126 (250℃≤T≤320℃). Anhydrite remained stable during rapid cooling of the sample chamber, showing that the gypsum-anhydrite transition involving both dissolution and precipitation processes is

  8. Rheological Behaviour and Microstructures of Natural Gypsum Experimentally Deformed in Simple Shear

    Barberini, V.; Burlini, L.; Rutter, E. H.; Dapiaggi, M.


    Gypsum is an important mineral of evaporitic rocks. Evaporites, interlayered within sedimentary sequences, play an important role in localizing the deformation especially in thrust tectonics (Apennines, Zagros, Gulf of Mexico, etc.) since are generally weaker than the other rocks; in some cases the deformation is accompanied by seismicity as in the Northern Apennines extensional systems. In order to determine the rheological and microstructural evolution of gypsum with strain, a set of experiments was performed on natural gypsum samples from Volterra (Tuscany, Italy). Experimental deformation tests were performed at confining pressures up to 300 MPa, at temperatures up to 130° C and at strain rates ranging between 6x10-4 and 5x10-6 s-1. In order to reach high shear strain values, we deformed gypsum specimens using both the torsion technique in the Paterson apparatus at ETH Zurich (up to γ = 5) and the sawcut-type assembly at 35° in a Heard-type apparatus at Manchester University (up to γ = 1.2). All samples have been studied by optical microscopy, to investigate the evolution of the microstructure with strain, and by XRD analysis, to determine whether and to what extent gypsum dehydrated during deformation. In torsion, the shear stress increased with the strain rate and decreased with the temperature. In general a peak stress was reached at γ between 0.5 and 1 (at higher temperatures is reached sooner). After the peak, a various amount of weakening occurred, and mechanical 'steady state' conditions were never reached. Weakening was up to 30-40%. Most of the times the jacket failure ended prematurely the experiment. The microstructure evolved from a deformation microstructure, where grains changed shape according to the bulk strain imposed, into a recrystallization microstructure, where grains were more aequant. Grain boundary migration recrystallization was very effective in resetting the microstructure after γ of 1 or 2. In the samples deformed using saw

  9. Arsenic uptake by gypsum and calcite: Modeling and probing by neutron and x-ray scattering

    Fernandez-Martinez, Alejandro; Roman-Ross, Gabriela; Johnson, Mark R; Bardelli, Fabrizio; Turrillas, Xavier; Charlet, Laurent


    Here we report on two structural studies performed on As-doped gypsum (CaSO4 2H2O) and calcite (CaCO3), using neutron (D20-ILL) and x-ray (ID11-ESRF) diffraction data and EXAFS (BM8-ESRF). The aim of this study is to determine whether As gets into the bulk of gypsum and calcite structures or is simply adsorbed on the surface. Different mechanisms of substitution are used as hypotheses. The combined Rietveld analysis of neutron and x-ray diffraction data shows an expansion of the unit cell volume proportional to the As concentration within the samples. DFT-based simulations confirm the increase of the unit cell volume proportional to the amount of carbonate or sulphate groups substituted. Interpolation of the experimental Rietveld data allows us to distinguish As substituted within the structure from that adsorbed on the surface of both minerals.

  10. Two distinctive new species of Commicarpus (Nyctaginaceae) from gypsum outcrops in eastern Ethiopia

    Friis, Ib; Gilbert, Michael G.; Weber, Odile;


    During field trips in 2013 and 2014, two distinctive plants belonging to the genus Commicarpus were collected in the Lele Hills, Bale Zone, eastern Ethiopia, on outcrops of sedimentary rock belonging to the Gorrahei Formation with high contents of gypsum. The plants are here described as two new...... in Commicarpus, being a small self-supporting shrub to 0.8 (– 1) m high. Both new species occur in small populations with restricted distribution; models based on the available information show that the potential distribution is also restricted. C. macrothamnus is here evaluated as Vulnerable (VU), while C....... leleensis, only known from the type, should remain Data Deficient (DD). Outcrops of gypsum with restricted-range species are well known from eastern Ethiopia and Somalia, but the locality with the two new species of Commicarpus is the most north-western and one of the highest sites recorded so far...

  11. Thermal Dehydration Kinetics of Gypsum and Borogypsum under Non-isothermal Conditions

    I.Y.Elbeyli; S.Piskin


    Thermal dehydration of gypsum and borogypsum was investigated under nonisothermal conditions in air by using simultaneous thermogravimetric-differential thermal analyzer. Nonisothermal experiments were carried out at various linear heating rates. Kinetics of dehydration in the temperature range of 373-503 K were evaluated from the DTA (differential thermal analysis)-TGA (thermogravimetric analysis) data by means of Coats-Redfern,Kissinger and Doyle Equations. Values of the activation energy and the pre-exponential factor of the dehydration were calculated. The results of thermal experiments and kinetic parameters indicated that borogypsum is similar to gypsum from dehydration mechanism point of view although it consists of boron and small amount of alkali metal oxides.

  12. Gypsum treated fly ash as a liner for waste disposal facilities

    Baig, A.A.; Sivapullaiah, P.V. [Indian Inst. of Science, Bangalore (India)


    Fly ash is now being used in geotechnical engineering and construction applications as a means of reducing the environmental impacts of fly ash generated in thermal power plants. Various additions are used to improve fly ash properties. This abstract discussed a study conducted to investigate lime and gypsum additions to fly ash. Lime amendments ranged from 0 to 10 per cent, while gypsum additions ranged from 0 to 2.5 per cent. Laboratory experiments were conducted to determine the hydraulic conductivity of compacted samples in moulds. The study showed wide variations in hydraulic conductivity for the various samples. The physico-chemical, chemical, and mineralogical changes in the fly ash amended samples were discussed.

  13. Accuracy of Gypsum Casts after Different Impression Techniques and Double Pouring.

    Silva, Stephania Caroline Rodolfo; Messias, Aion Mangino; Abi-Rached, Filipe de Oliveira; de Souza, Raphael Freitas; Reis, José Maurício Dos Santos Nunes


    This study evaluated the accuracy of gypsum casts after different impression techniques and double pouring. Ten patients were selected and for each one it was obtained 5 partial putty/wash impressions with vinyl polysiloxane (VPS) material from teeth #13 to #16 with partial metal stock trays. The following techniques were performed: (1) one-step; two-step relief with: (2) PVC film; (3) slow-speed tungsten carbide bur and scalpel blade, (4) small movements of the tray and (5) without relief-negative control. The impressions were disinfected with 0.5% sodium hypochlorite for 10 minutes and stored during 110 and 230 minutes for the first and second pouring, respectively, with type IV gypsum. Three intra-oral lateral photographs of each patient were taken using a tripod and a customized radiographic positioner. The images were imported into ImageJ software and the total area of the buccal surface from teeth #13 to #16 was measured. A 4.0% coefficient of variance was criterion for using these measurements as Baseline values. The casts were photographed and analyzed using the same standardization for the clinical images. The area (mm2) obtained from the difference between the measurements of each gypsum cast and the Baseline value of the respective patient were calculated and analyzed by repeated-measures two way-ANOVA and Mauchly's Sphericity test (α = 0.05). No significant effect was observed for Impression technique (P = 0.23), Second pouring (P = 0.99) and their interaction (P = 0.25). The impression techniques and double pouring did not influence the accuracy of the gypsum casts.

  14. Use of textile fibres in the reinforcement of a gypsum-cork based composite material

    Vasconcelos, Graça; Camões, Aires; Fangueiro, Raúl, ed. lit.; Vila-Chã, Nuno; Jesus, Carlos M. G.; Cunha, Fernando Eduardo Macedo


    The study presented herein focus on the analysis of a series of experimental tests aiming at characterizing the performance of distinct textile fibers acting as a reinforcement of a gypsum-cork composite material. Two groups of textile fibers were selected, namely synthetic fibers (glass and basalt) and natural fibers (banana and sisal). The reinforced composite material was submitted to distinct types of loading, namely compression tests, which it was possible to obtain the compressive stren...

  15. The effect of gypsum products and separating materials on the typography of denture base materials.

    Firtell, D N; Walsh, J F; Elahi, J M


    The typography of polymethyl methacrylate processed against various gypsum products coated with various separating materials was studied under an SEM. Tinfoil and two commercial tin foil substitutes were used as separating material during processing, and the surfaces of the resulting acrylic resin forms were studied for topographical differences. Tinfoil and alpha 2 hemihydrates produced the smoothest surfaces. As a practical solution, a good quality tinfoil substitute and alpha 1 hemihydrate could be used when processing polymethyl methacrylate resin.

  16. Mercury transportation in soil via using gypsum from flue gas desulfurization unit in coal-fired power plant.

    Wang, Kelin; Orndorff, William; Cao, Yan; Pan, Weiping


    The mercury flux in soils was investigated, which were amended by gypsums from flue gas desulphurization (FGD) units of coal-fired power plants. Studies have been carried out in confined greenhouses using FGD gypsum treated soils. Major research focus is uptakes of mercury by plants, and emission of mercury into the atmosphere under varying application rates of FGD gypsum, simulating rainfall irrigations, soils, and plants types. Higher FGD gypsum application rates generally led to higher mercury concentrations in the soils, the increased mercury emissions into the atmosphere, and the increased mercury contents in plants (especially in roots and leaves). Soil properties and plant species can play important roles in mercury transports. Some plants, such as tall fescue, were able to prevent mercury from atmospheric emission and infiltration in the soil. Mercury concentration in the stem of plants was found to be increased and then leveled off upon increasing FGD gypsum application. However, mercury in roots and leaves was generally increased upon increasing FGD gypsum application rates. Some mercury was likely absorbed by leaves of plants from emitted mercury in the atmosphere.

  17. Implications of moisture content determination in the environmental characterisation of FGD gypsum for its disposal in landfills

    Alvarez-Ayuso, E. [Department of Environmental Geology, Institute of Earth Sciences ' Jaume Almera' (CSIC), C/ Lluis Sole i Sabaris s/n, 08028 Barcelona (Spain)], E-mail:; Querol, X. [Department of Environmental Geology, Institute of Earth Sciences ' Jaume Almera' (CSIC), C/ Lluis Sole i Sabaris s/n, 08028 Barcelona (Spain); Tomas, A. [Endesa Generacion, S.A., C/ Ribera de Loira 60, 28042 Madrid (Spain)


    The leachable contents of elements of environmental concern considered in the Council Decision 2003/33/EC on waste disposal were determined in flue gas desulphurisation (FGD) gypsum. To this end, leaching tests were performed following the standard EN-12457-4 which specifies the determination of the dry mass of the material at 105 deg. C and the use of a liquid to solid (L/S) ratio of 10 l kg{sup -1} dry matter. Additionally, leaching tests were also carried out taking into account the dry mass of the material at 60 deg. C and using different L/S ratios (2, 5, 8, 10, 15 and 20 l kg{sup -1} dry matter). It was found that the dry mass determination at 105 deg. C turns out to be inappropriate for FGD gypsum since at this temperature gypsum transforms into bassanite, and so, in addition to moisture content, crystalline water is removed. As a consequence the moisture content is overvalued (about 16%), what makes consider a lower L/S ratio than that specified by the standard EN-12457-4. As a result the leachable contents in FGD gypsum are, in general, overestimated, what could lead to more strict environmental requirements for FGD gypsum when considering its disposal in landfills, specially concerning those elements (e.g., F) risking the characterisation of FGD gypsum as a waste acceptable at landfills for non-hazardous wastes.

  18. Mercury transportation in soil via using gypsum from flue gas desulfurization unit in coal-fired power plant

    Kelin Wang; William Orndorff; Yan Cao; Weiping Pan


    The mercury flux in soils was investigated,which were amended by gypsums from flue gas desulphurization (FGD) units of coalfired power plants.Studies have been carried out in confined greenhouses using FGD gypsum treated soils.Major research focus is uptakes of mercury by plants,and emission of mercury into the atmosphere under varying application rates of FGD gypsum,simulating rainfall irrigations,soils,and plants types.Higher FGD gypsum application rates generally led to higher mercury concentrations in the soils,the increased mercury emissions into the atmosphere,and the increased mercury contents in plants (especially in roots and leaves).Soil properties and plant species can play important roles in mercury transports.Some plants,such as tall fescue,were able to prevent mercury from atmospheric emission and infiltration in the soil.Mercury concentration in the stem of plants was found to be increased and then leveled off upon increasing FGD gypsum application.However,mercury in roots and leaves was generally increased upon increasing FGD gypsum application rates.Some mercury was likely absorbed by leaves of plants from emitted mercury in the atmosphere.

  19. Modelling of Fluidised Geomaterials: The Case of the Aberfan and the Gypsum Tailings Impoundment Flowslides

    Paola Dutto


    Full Text Available The choice of a pure cohesive or a pure frictional viscoplastic model to represent the rheological behaviour of a flowslide is of paramount importance in order to obtain accurate results for real cases. The principal goal of the present work is to clarify the influence of the type of viscous model—pure cohesive versus pure frictional—with the numerical reproduction of two different real flowslides that occurred in 1966: the Aberfan flowslide and the Gypsum tailings impoundment flowslide. In the present work, a depth-integrated model based on the v - p w Biot–Zienkiewicz formulation, enhanced with a diffusion-like equation to account for the pore pressure evolution within the soil mass, is applied to both 1966 cases. For the Aberfan flowslide, a frictional viscous model based on Perzyna viscoplasticity is considered, while a pure cohesive viscous model (Bingham model is considered for the case of the Gypsum flowslide. The numerical approach followed is the SPH method, which has been enriched by adding a 1D finite difference grid to each SPH node in order to improve the description of the pore water evolution in the propagating mixture. The results obtained by the performed simulations are in agreement with the documentation obtained through the UK National Archive (Aberfan flowslide and the International Commission of large Dams (Gypsum flowslide.

  20. Histological Comparison in Rats between Carbonate Apatite Fabricated from Gypsum and Sintered Hydroxyapatite on Bone Remodeling

    Yasunori Ayukawa


    Full Text Available Carbonate apatite (CO3Ap, the form of apatite found in bone, has recently attracted attention. The purpose of the present study was to histologically evaluate the tissue/cellular response toward the low-crystalline CO3Ap fabricated using a dissolution-precipitation reaction with set gypsum as a precursor. When set gypsum was immersed in a 100°C 1 mol/L Na3PO4 aqueous solution for 24 h, the set gypsum transformed into CO3Ap. Both CO3Ap and sintered hydroxyapatite (s-HAp, which was used as a control, were implanted into surgically created tibial bone defects of rats for histological evaluation. Two and 4 weeks after the implantation, histological sections were created and observed using light microscopy. The CO3Ap granules revealed both direct apposition of the bone matrix by osteoblasts and osteoclastic resorption. In contrast, the s-HAp granules maintained their contour even after 4 weeks following implantation which implied that there was a lack of replacement into the bone. The s-HAp granules were sometimes encapsulated with fibrous tissue, and macrophage polykaryon was occasionally observed directly apposed to the implanted granules. From the viewpoint of bone remodeling, the CO3Ap granules mimicked the bone matrix, suggesting that CO3Ap may be an appropriate bone substitute.

  1. Do Ca2+-adsorbing ceramics reduce the release of calcium ions from gypsum-based biomaterials?

    Belcarz, Anna; Zalewska, Justyna; Pałka, Krzysztof; Hajnos, Mieczysław; Ginalska, Grazyna


    Bone implantable materials based on calcium sulfate dihydrate dissolve quickly in tissue liquids and release calcium ions at very high levels. This phenomenon induces temporary toxicity for osteoblasts, may cause local inflammation and delay the healing process. Reduction in the calcium ion release rate by gypsum could be therefore beneficial for the healing of gypsum-filled bone defects. The aim of this study concerned the potential use of calcium phosphate ceramics of various porosities for the reduction of high Ca(2+) ion release from gypsum-based materials. Highly porous ceramics failed to reduce the level of Ca(2+) ions released to the medium in a continuous flow system. However, it succeeded to shorten the period of high calcium level. It was not the phase composition but the high porosity of ceramics that was found crucial for both the shortening of the Ca(2+) release-related toxicity period and intensification of apatite deposition on the composite. Nonporous ceramics was completely ineffective for this purpose and did not show any ability to absorb calcium ions at a significant level. Moreover, according to our observations, complex studies imitating in vivo systems, rather than standard tests, are essential for the proper evaluation of implantable biomaterials.

  2. Surface induced constant composition crystal growth kinetics studies. The brushite gypsum system

    Hina, A.; Nancollas, G. H.; Grynpas, M.


    The possible oriented growth of one crystalline phase on the surface of another is especially important in systems containing both phosphate and sulfate salts of calcium. Whether the overgrowth results from a true epitaxial relationship is dependent on factors such as the thermodynamic driving forces and the free energies of the surfaces. Despite the fact that calcium sulfate dihydrate (CSD, gypsum) and calcium hydrogen phosphate dihydrate (DCPD, brushite) show many crystallographic and structural analogies, their surface reactions are quite different. The nucleation and growth of gypsum on brushite surfaces has been investigated in supersaturated solutions of calcium sulfate dihydrate at 25.0°C using the constant composition (CC) method. During the kinetics experiments, the harvested solid phases were examined by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDS). Induction periods, τ, preceding the initial formation of gypsum crystals at the brushite surfaces, varied markedly with relative supersaturation, σ. A thin layer wicking method was used to investigate the interfacial free energies of the growing phases, and these data were also calculated from the kinetics results. The interfacial free energy, γ, estimated from initial growth rates was 8.4 mJ m -2, while that calculated from the induction times was 8.9 mJ m -2. These values were in agreement with those determined directly using thin layer wicking.

  3. Risk minimisation of FGD gypsum leachates by incorporation of aluminium sulphate

    Alvarez-Ayuso, E. [Department of Environmental Geology, Institute of Earth Sciences ' Jaume Almera' (CSIC), C/ Lluis Sole i Sabaris, s/n, 08028 Barcelona (Spain); Department of Environmental Geochemistry, IRNASA, CSIC, Apto. 257, 37071 Salamanca (Spain)], E-mail:; Querol, X. [Department of Environmental Geology, Institute of Earth Sciences ' Jaume Almera' (CSIC), C/ Lluis Sole i Sabaris, s/n, 08028 Barcelona (Spain); Ballesteros, J.C.; Gimenez, A. [Endesa Generacion, S.A., C/ Ribera de Loira, 60, 28042 Madrid (Spain)


    The incorporation of aluminium sulphate to (flue gas desulphurisation) FGD gypsum before its disposal was investigated as a way to minimise the risk supposed by the high fluoride content of its leachates. Using a bath method the kinetic and equilibrium processes of fluoride removal by aluminium sulphate were studied at fluoride/aluminium molar concentration (F/Al) ratios in the range 1.75 10{sup -2}-1.75 under the pH conditions (about 6.5) of FGD gypsum leachates. It was found that fluoride removal was a very fast process at any of the (F/Al) ratios subject of study, with equilibrium attained within the first 15 min of interaction. High decreases in solution fluoride concentrations (50-80%) were found at the equilibrium state. The use of aluminium sulphate in the stabilization of FGD gypsum proved to greatly decrease its fluoride leachable content (in the range 20-90% for aluminium sulphate doses of 0.1-5%, as determined by the European standard EN 12457-4). Such fluoride leaching minimisation assures the characterization of this by-product as a waste acceptable at landfills for non-hazardous wastes according to the Council Decision 2003/33/EC on waste disposal. Furthermore, as derived from column leaching studies, the proposed stabilization system showed to be highly effective in simulated conditions of disposal, displaying fluoride leaching reduction values about 55 and 80% for aluminium sulphate added amounts of 1 and 2%, respectively.

  4. Numerical modelling and thermal simulation of PCM-gypsum composites with ESP-r

    Heim, D.; Clarke, J.A. [Department of Building Physics and Building Materials, Technical University of Lodz, Lodz (Poland)


    The aim of the present work is to refine the ESP-r system by incorporating phase change materials (PCMs) modelling. The behaviour of PCMs is modelled using ESP-r's special materials facility. The effect of phase transition is added to the energy balance equation as a latent heat generation term according to the so-called effective heat capacity method. Numerical simulations were conducted for a multi-zone, highly glazed and naturally ventilated passive solar building. PCM-impregnated gypsum plasterboard was used as an internal room lining. The air, surface and resultant temperatures were compared with the no-PCM case and the diurnal latent heat storage effect was analysed. While this effect did not cause a considerable reduction in the diurnal temperature fluctuation, the PCMs did effectively store solar energy in the transitions periods. Additionally, the energy requirement at the beginning and end of the heating season was estimated and compared with ordinary gypsum wallboard. Within this comparison, the PCM composite solidification temperature was 22 {sup o}C (i.e. 2 K higher than the heating set-point for the room). The results show that solar energy stored in the PCM-gypsum panels can reduce the heating energy demand by up to 90% at times during the heating season. (author)

  5. Developing biodiversity indicators on a stakeholders' opinions basis: the gypsum industry Key Performance Indicators framework.

    Pitz, Carline; Mahy, Grégory; Vermeulen, Cédric; Marlet, Christine; Séleck, Maxime


    This study aims to establish a common Key Performance Indicators (KPIs) framework for reporting about the gypsum industry biodiversity at the European level. In order to integrate different opinions and to reach a consensus framework, an original participatory process approach has been developed among different stakeholder groups: Eurogypsum, European and regional authorities, university scientists, consulting offices, European and regional associations for the conservation of nature, and the extractive industry. The strategy is developed around four main steps: (1) building of a maximum set of indicators to be submitted to stakeholders based on the literature (Focus Group method); (2) evaluating the consensus about indicators through a policy Delphi survey aiming at the prioritization of indicator classes using the Analytic Hierarchy Process method (AHP) and of individual indicators; (3) testing acceptability and feasibility through analysis of Environmental Impact Assessments (EIAs) and visits to three European quarries; (4) Eurogypsum final decision and communication. The resulting framework contains a set of 11 indicators considered the most suitable for all the stakeholders. Our KPIs respond to European legislation and strategies for biodiversity. The framework aims at improving sustainability in quarries and at helping to manage biodiversity as well as to allow the creation of coherent reporting systems. The final goal is to allow for the definition of the actual biodiversity status of gypsum quarries and allow for enhancing it. The framework is adaptable to the local context of each gypsum quarry.

  6. Thermal testing and numerical simulation of gypsum wallboards incorporated with different PCMs content

    Borreguero, Ana M.; Luz Sanchez, M.; Valverde, Jose Luis; Carmona, Manuel; Rodriguez, Juan F. [Department of Chemical Engineering, University of Castilla - La Mancha, Av. Camilo Jose Cela s/n, 13004 Ciudad Real (Spain)


    A mathematical model based on the Fourier heat conduction equation for one dimension was developed. The complexity of the mathematical solution of this stiff set of differential equations that use boundary conditions that move with the solid-liquid interface was simplified by using an apparent heat capacity (c{sub p}{sup ap}) dependent on temperature and obtained by Modulated Differential Scanning Calorimetry (MDSC). The performance of this model was confirmed by using a home-made experimental installation for the thermal characterization of solid materials. Theoretical curves obtained for gypsum blocks with three different contents of phase change materials (PCMs) were in agreement with experimental ones, indicating that this thermal process can be reproduced theoretically by using the c{sub p}{sup ap} of each block and a unique thermal conductivity of the pure gypsum. The other physical and thermal properties were taken from literature or supplied by the manufacturers. Results also indicated that the higher the PCM content, the higher the energy storage capacity of the wallboard and the lower the wall temperature variation. Furthermore, it was found that a block containing a 5 wt.% of microcapsule allows the reduction of gypsum thickness by 8.5%, maintaining the same insulating effect. Thus, these kind of material can be used to improve comfort, save energy in buildings and even reduce the weight of wallboards. (author)

  7. Mechanical properties of simulated Mars materials: gypsum-rich sandstones and lapilli tuff

    Morrow, Carolyn; Lockner, David; Okubo, Chris


    Observations by the Mars Exploration Rover (MER) Opportunity, and other recent studies on diagenesis in the extensive equatorial layered deposits on Mars, suggest that the likely lithologies of these deposits are gypsum-rich sandstones and tuffaceous sediments (for example, Murchie and others, 2009; Squyres and others, 2012; Zimbelman and Scheidt, 2012). Of particular interest is how the diagenesis history of these sediments (degree of cementation and composition) influences the strength and brittle behavior of the material. For instance, fractures are more common in lower porosity materials under strain, whereas deformation bands, characterized by distributed strain throughout a broader discontinuity in a material, are common in higher porosity sedimentary materials. Such discontinuities can either enhance or restrict fluid flow; hence, failure mode plays an important role in determining the mechanics of fluid migration through sediments (Antonellini and Aydin, 1994; 1995; Taylor and Pollard, 2000; Ogilvie and Glover, 2001). As part of a larger study to characterize processes of fault-controlled fluid flow in volcaniclastic and gypsum-rich sediments on Mars, we have completed a series of laboratory experiments to focus on how gypsum clast content and degree of authigenic cementation affects the strength behavior of simulated Mars rocks. Both axial deformation and hydrostatic pressure tests were done at room temperature under dry conditions.

  8. Laboratory Salinization of Brazilian Alluvial Soils and the Spectral Effects of Gypsum

    Luis Clenio J. Moreira


    Full Text Available Irrigation-induced salinization is an important land degradation process that affects crop yield in the Brazilian semi-arid region, and gypsum has been used as a corrective measure for saline soils. Fluvent soil samples (180 were treated with increasing levels of salinization of NaCl, MgCl2 and CaCl2. The salinity was gauged using electrical conductivity (EC. Gypsum was added to one split of these samples before they were treated by the saline solutions. Laboratory reflectance spectra were measured at nadir under a controlled environment using a FieldSpec spectrometer, a 250-W halogen lamp and a Spectralon panel. Variations in spectral reflectance and brightness were evaluated using principal component analysis, as well as the continuum-removed absorption depths of major features at 1450, 1950, 1750 and 2200 nm for both the gypsum-treated (TG and non-treated (NTG air-dried soil samples as a function of EC. Pearson’s correlation coefficients of reflectance and the band depth with EC were also obtained to establish the relationships with salinity. Results showed that NTG samples presented a decrease in reflectance and brightness with increasing CaCl2 and MgCl2 salinization. The reverse was observed for NaCl. Gypsum increased the spectral reflectance of the soil. The best negative correlations between reflectance and EC were observed in the 1500–2400 nm range for CaCl2 and MgCl2, probably because these wavelengths are most affected by water absorption, as Ca and Mg are much more hygroscopic than Na. These decreased after chemical treatment with gypsum. The most prominent features were observed at 1450, 1950 and 1750 nm in salinized-soil spectra. The 2200-nm clay mineral absorption band depth was inversely correlated with salt concentration. From these features, only the 1750 and 2200 nm ones are within atmospheric absorption windows and can be more easily measured using hyperspectral sensors.

  9. Theoretical determination of O and S isotope fractionations between gypsum and aqueous sulfate

    Liu, Y.; Bao, H.


    Some non-labile oxyanions, such as sulfate (SO42-) or nitrate (NO3-), do not exchange O atoms readily with O in water at ambient temperatures. They often behave like a single atom during mineral precipitation, dissolution, adsorption, and even microbial transport. Considering the many different isotopologues these oxyanions usually possess, for example, SO42- has 32-16-16-16-16, 34-16-16-16-16, 32-18-16-16-16, 34-18-16-16-16, …, etc., the behaviour of isotope fractionation for different elements in the oxyanions (e.g., O and S) may lead to certain degrees of coupling during different physical, chemical, and biological processes. Here, we use an aqueous sulfate - solid gypsum (CaSO4-2H2O) system to illustrate a first-principle approach to calculating the isotope fractionation factors and their coupling for O and S in sulfate during gypsum precipitation. Using Urey model or Bigeleisen-Mayer equation in combination with quantum chemistry calculations (at B3LYP/6-311+G(2df,p) level), we have calculated equilibrium isotope fractionation factors α18 and α34 for tens of isotopologues of SO42-. We use a time-consuming yet explicit solvent model (i.e. “water-droplet”) to precisely evaluate solvation effects for aqueous sulfate species. A large and partially fixed cluster model is used for simulating gypsum mineral surface. Our results show that the equilibrium fractionations at 25°C between solid gypsum and aqueous sulfate are ~ 2.5 and 1.6 ‰ for the Δδ18O and Δδ34S, respectively. Without considering ion-pair effect on sulfate anion in solution, however, the corresponding Δδ18O and Δδ34S become ~ 4.4 and 2.8 ‰, respectively. Our work presents a new approach to predicting isotope fractionation behaviour for no-labile species at equilibrium and lays the ground for evaluating kinetic effects. The results also shed lights on the mechanism and model for gypsum crystal growth at molecular level.

  10. EXAFS speciation and phytoavailability of Pb in a contaminated soil amended with compost and gypsum.

    Hashimoto, Yohey; Yamaguchi, Noriko; Takaoka, Masaki; Shiota, Kenji


    Due to unregulated uses of lead pellets for hunting purposes in Japan, soils and sediments in some river basins and wetlands have become highly contaminated with Pb. Deterioration of natural vegetation has occurred sporadically in these areas, and therefore revegetation is needed for ecological restoration. The objectives of the present study were to assess the effects of surface applications of compost and gypsum amendments on Pb availability to a watercress plant (Nasturtium officinale W.T. Aiton) and molecular-scale speciation of Pb in soil solid phases. The compost and gypsum amendments significantly decreased dissolved Pb and Sb in pore water. The concentration of Pb in aboveground plant tissues was 190mg kg(-1) in the control soil and was reduced to soils. The concentration of Sb in plants grown in the control soil was 13mg kg(-1), whereas that in the soils receiving compost and gypsum decreased below detectable levels. Redox potential was higher in vegetated soils (ave. 349mV) than in the unvegetated soils (ave. 99mV) due to oxygen introduced by plant roots. Extended X-ray absorption fine structure (EXAFS) spectroscopy illustrated that Pb occurred as Pb sorbed on birnessite and/or ferrihydrite (Pb-Mn/Fe, ~60%) and Pb sorbed on organic matter (Pb-org, ~15%), and galena (PbS, ~10%) in the vegetated and unvegetated control soils. The compost amendment increased the proportion of Pb-org by 2-fold than in the control soils. The amended soils with plant growth decreased the proportion of Pb-Mn/Fe phases by half of that without plant growth. Galena and anglesite (PbSO(4)) were not detected in compost-amended soils and even in gypsum-amended soils since a significant soil reduction to anoxic levels did not occur in the entire soil. The present study indicated that, under flooded conditions, surface applications of compost and gypsum amendments reduced plant Pb uptake from the Pb contaminated soil. Crown Copyright © 2010. Published by Elsevier B.V. All rights

  11. Reforestation and landscape reconstruction in gypsum mine area from the semiarid region of NE Brazil

    Bittar, S. M. B.; Straaten, P. V.; de Araujo Vieura Santos, M. de Fatima; Agra Bezerra da Silva, Y. J.; da Silva, M.; Saraiva de Melo Pinheiro, T.; Gusmao Didier de Moraes, F.; de Aguiar Accioly, A. M.; Alves de Santana, S. R.; dos Santos, H. A.; de Carvalho, D. M.; de Lima Ferreira, G.; de Carvalho Santos, C.


    In the Araripe region, Northeast Brazil, exist the world's second largest reserve of gypsum, estimated at over than one billion tons, which accounts for 95% of the Brazilian production and constitutes an important segment of the regional economy. The gypsum deposit occurs in the Lower Cretaceous Santana Formation of the Araripe basin, which is constituted by siltstones, marls, limestones, shales and gypsum layers. The ore extraction is from an open pit, on simple benches with a height of about 15 meters. Activities in mining operations involve stripping, drilling, loading explosives, blast, fragmentation and block loading / transport. Currently, gypsum mining and processing results in major changes in the landscape (pits and wastes heaps sedimentary rocks and soil mixture), deforestation of the "caatinga" ecosystem for use as firewood in small calcinations, dust pollution and changes in hydrology. To promote environmental remediation of this area, a multidisciplinary research has being done with the aim to support reforestation at the wastes heaps. The study involved the following activities: collection and physical, chemical and mineralogical characterization of mine waste materials; a floristic survey around the mines (botanical identification and measuring physical parameters in 16 plots, in order to identify which species are best suited to the conditions of the substrate at the mine site); an experiment (randomized block design) developed in a greenhouse, where seedlings of various native tree species were grown in a "constructed soil" made up of gypsum waste combined with chicken, goat and cattle manure, aimed to select tree species and soil treatment to be used in a waste heap; and an assessment of water quality for irrigation of the reforestation areas. The waste materials consist of large clayey aggregates, which may present physical/chemical properties unfavorable for plant development. The mineralogy of the sand fraction (> 85% quartz, gypsum and

  12. Bacterial Communities and the Nitrogen Cycle in the Gypsum Soils of Cuatro Ciénegas Basin, Coahuila: A Mars Analogue

    López-Lozano, Nguyen E.; Eguiarte, Luis E.; Bonilla-Rosso, Germán; García-Oliva, Felipe; Martínez-Piedragil, Celeste; Rooks, Christine; Souza, Valeria


    The OMEGA/Mars Express hyperspectral imager identified gypsum at several sites on Mars in 2005. These minerals constitute a direct record of past aqueous activity and are important with regard to the search of extraterrestrial life. Gale Crater was chosen as Mars Science Laboratory Curiosity's landing site because it is rich in gypsum, as are some desert soils of the Cuatro Ciénegas Basin (CCB) (Chihuahuan Desert, Mexico). The gypsum of the CCB, which is overlain by minimal carbonate deposits...

  13. Limestone, gypsum and residual effect of fertilizers in the biomass production and nutrient cycling of millet plants

    Maria da Conceição Santana Carvalho


    Full Text Available Cover crops can provide a higher nutrient cycling. This study aimed to determine the effect of annual applications of gypsum and lime to the soil surface and of fertilizer doses to the previous crop (soybean in the dry biomass production and nutrient accumulation by plants of pearl millet grown in succession, under no-tillage system. The experimental design was randomized blocks, in a 4x4 factorial scheme, with four replications. Treatments consisted of the combination of four types of soil conditioner (lime, lime + gypsum, gypsum and control, split in three parts (2 t ha-1 of lime and 1,0 t ha-1 of gypsum; 2 t ha-1 of lime and 1 t ha-1 of gypsum; and 1 t ha-1 of lime and 0.5 t ha-1 of gypsum, and four fertilizing rates with P (triple and simple superphosphate and K (potassium chloride (0%, 50%, 100% and 150% of the recommended fertilizing, applied at the sowing of the previous crop (soybean. Liming provided increments in the dry biomass production and in the accumulation of nutrients (N, P, K, Ca, Mg and S by millet plants. The application of gypsum did not increase the millet dry biomass yield. The use of increasing rates of fertilizers in the previous crop (soybean increased the biomass dry matter, density and accumulation of nutrients by millet plants. The intercropping of millet as a cover crop, with the residual effect of the fertilizer applied in the summer crop, provided a nutrient cycling that can be used by the following crops.

  14. Long-term erosion rate measurements in gypsum caves of Sorbas (SE Spain) by the Micro-Erosion Meter method

    Sanna, Laura; De Waele, Jo; Calaforra, José Maria; Forti, Paolo


    The present work deals with the results of long-term micro-erosion measurements in the most important gypsum cave of Spain, the Cueva del Agua (Sorbas, Almeria, SE Spain). Nineteen MEM stations were positioned in 1992 in a wide range of morphological and environmental settings (gypsum floors and walls, carbonate speleothems, dry conduits and vadose passages) inside and outside the cave, on gypsum and carbonate bedrocks and exposed to variable degree of humidity, different air flow and hydrodynamic conditions. Four different sets of stations have been investigated: (1) the main cave entrance (Las Viñicas spring); (2) the main river passage; (3) the abandoned Laboratory tunnel; and (4) the external gypsum surface. Data over a period of about 18 years are available. The average lowering rates vary from 0.014 to 0.016 mm yr- 1 near the main entrance and in the Laboratory tunnel, to 0.022 mm - 1 on gypsum floors and 0.028 mm yr- 1 on carbonate flowstones. The denudation data from the external gypsum stations are quite regular with a rate of 0.170 mm yr- 1. The observations allowed the collecting of important information concerning the feeding of the karst aquifer not only by infiltrating rainwater, but under present climate conditions also by water condensation of moist air flow. This contribution to the overall karst processes in the Cueva del Agua basin represents over 20% of the total chemical dissolution of the karst area and more than 50% of the speleogenetically removed gypsum in the cave system, thus representing all but a secondary role in speleogenesis. Condensation-corrosion is most active along the medium walls, being slower at the roof and almost absent close to the floor. This creates typical corrosion morphologies such as cupola, while gypsum flowers develop where evaporation dominates. This approach also shows quantitatively the morphological implications of condensation-corrosion processes in gypsum karst systems in arid zones, responsible for an

  15. Visualization of the structural changes in plywood and gypsum board during the growth of Chaetomium globosum and Stachybotrys chartarum.

    Lewinska, Anna M; Hoof, Jakob B; Peuhkuri, Ruut H; Rode, Carsten; Lilje, Osu; Foley, Matthew; Trimby, Patrick; Andersen, Birgitte


    Fungal growth in indoor environments is associated with many negative health effects. Many studies focus on brown- and white-rot fungi and their effect on wood, but there is none that reveals the influence of soft-rot fungi, such as Stachybotrys spp. and Chaetomium spp., on the structure of building materials such as plywood and gypsum wallboard. This study focuses on using micro-computed tomography (microCT) to investigate changes of the structure of plywood and gypsum wallboard during fungal degradation by S. chartarum and C. globosum. Changes in the materials as a result of dampness and fungal growth were determined by measuring porosity and pore shape via microCT. The results show that the composition of the building material influenced the level of penetration by fungi as shown by scanning electron microscopy (SEM). Plywood appeared to be the most affected, with the penetration of moisture and fungi throughout the whole thickness of the sample. Conversely, fungi grew only on the top cardboard in the gypsum wallboard and they did not have significant influence on the gypsum wallboard structure. The majority of the observed changes in gypsum wallboard occurred due to moisture. This paper suggests that the mycelium distribution within building materials and the structural changes, caused by dampness and fungal growth, depend on the type of the material.

  16. GyPSuM: A Detailed Tomographic Model of Mantle Density and Seismic Wave Speeds

    Simmons, N A; Forte, A M; Boschi, L; Grand, S P


    GyPSuM is a tomographic model fo mantle seismic shear wave (S) speeds, compressional wave (P) speeds and detailed density anomalies that drive mantle flow. the model is developed through simultaneous inversion of seismic body wave travel times (P and S) and geodynamic observations while considering realistic mineral physics parameters linking the relative behavior of mantle properties (wave speeds and density). Geodynamic observations include the (up to degree 16) global free-air gravity field, divergence of the tectonic plates, dynamic topography of the free surface, and the flow-induced excess ellipticity of the core-mantle boundary. GyPSuM is built with the philosophy that heterogeneity that most closely resembles thermal variations is the simplest possible solution. Models of the density field from Earth's free oscillations have provided great insight into the density configuration of the mantle; but are limited to very long-wavelength solutions. Alternatively, simply scaling higher resolution seismic images to density anomalies generates density fields that do not satisfy geodynamic observations. The current study provides detailed density structures in the mantle while directly satisfying geodynamic observations through a joint seismic-geodynamic inversion process. Notable density field observations include high-density piles at the base of the superplume structures, supporting the fundamental results of past normal mode studies. However, these features are more localized and lower amplitude than past studies would suggest. When we consider all seismic anomalies in GyPSuM, we find that P and S-wave speeds are strongly correlated throughout the mantle. However, correlations between the high-velocity S zones in the deep mantle ({approx} 2000 km depth) and corresponding P-wave anomalies are very low suggesting a systematic divergence from simplified thermal effects in ancient subducted slab anomalies. Nevertheless, they argue that temperature variations are

  17. 常压盐溶液脱硫石膏转化生成α-半水石膏%Transformation of Flue-Gas-Desulfurization Gypsum to α-Hemihydrated Gypsum in Salt Solution at Atmospheric Pressure

    吴晓琴; 童仕唐; 官宝红; 吴忠标


    Direct phase transformation of flue gas desulfurization gypsum in hot salt solution at atmospheric pressure was investigated. The effects of temperature, salt species, salt concentration, solids content, pH and modifier were examined. The crystals obtained under different conditions and solubility of calcium sulfate in contact with solid gypsum were also determined. α-Calcium sulfate hemihydrate crystals of stubby columnar shape and regular pentahedral sides were obtained under the following conditions: salt concentration 20%-30%, operation temperature 95-100 ℃, solids mass content in the slurry 10%-30% and neutral pH. Thermodynamic analysis revealed that phase transformation of calcium sulfate dihydrate to α-calcium suffate hemihydrate occurs because of the difference in solubilities between the two solid gypsum phases in this system.

  18. Climatic control on the growth of gigantic gypsum crystals within hypogenic caves (Naica mine, Mexico)?

    Garofalo, Paolo S.; Fricker, Mattias B.; Günther, Detlef; Forti, Paolo; Mercuri, Anna-Maria; Loreti, Mara; Capaccioni, Bruno


    Three hypogenic caves within the Naica mine of Mexico ( Cueva de los Cristales — CLC, Ojo de la Reina — OR, and Cueva de las Velas — CLV) host spectacular gypsum crystals up to 11 m in length. These caves are close to another shallow cave of the area ( Cueva de las Espadas — CLE), with which they cover a 160 m-deep vertical section of the local drainage basin. Similar to other hypogenic caves, all these caves lack a direct connection with the land surface and should be unrelated with climate. A record of multi-technique fluid inclusion data and pollen spectra from cave and mine gypsum indicates surprisingly that climatic changes occurring at Naica could have controlled fluid composition in these caves, and hence crystal growth. Microthermometry and LA-ICP-Mass Spectrometry of fluid inclusions indicate that the shallow, chemically peculiar, saline fluid (up to 7.7 eq. wt.%NaCl) of CLE could have formed from evaporation, during a dry and hot climatic period. The fluid of the deep caves was instead of low salinity (˜ 3.5 eq. wt.% NaCl) and chemically homogeneous, and was poorly affected by evaporation. We propose that mixing of these two fluids, generated at different depths of the Naica drainage basin, determined the stable supersaturation conditions for the gigantic gypsum crystals to grow. Fluid mixing was controlled by the hydraulic communication between CLE and the other deep caves, and must have taken place during cycles of warm-dry and fresh-wet climatic periods, which are known to have occurred in the region. Pollen grains from a 35 ka-old gypsum crystal of CLC corresponds to a fairly homogenous catchment basin made of a mixed broadleaf wet forest, which suggests precipitation during a fresh-wet climatic period and confirms our interpretation of the fluid inclusion data. The unusual combination of geological and geochemical factors of Naica suggests that other hypogenic caves found elsewhere may not host similar crystals. However, this work shows that

  19. Utilization of the gypsum from a wet limestone flue gas desulfurization process

    Chou, I.-Ming; Patel, V.; Lytle, J.M.; Chou, S.J.; Carty, R.H.


    The authors have been developing a process which converts FGD-gypsum to ammonium sulfate fertilizer with precipitated calcium carbonate as a by-product during the conversion. Preliminary cost estimates suggest that the process is economically feasible when ammonium sulfate crystals are produced in a granular size (1.2 to 3.3 mm), instead of a powder form. However, if additional revenue from the sale of the PCC for higher-value commercial application is applicable, this could further improve the economics of the process. Ammonium sulfate is known to be an excellent source of nitrogen and sulfur in fertilizer for corn and wheat production. It was not known what impurities might co-exist in ammonium sulfate derived from scrubber gypsum. Before the product could be recommended for use on farm land, the impurities and their impact on soil productivity had to be assessed. The objectives of this phase of the study were to evaluate the chemical properties of ammonium sulfate made from the FGD-gypsum, to estimate its effects on soil productivity, and to survey the marketability of the two products. The results of this phase of the study indicated that the impurities in the ammonium sulfate produced would not impose any practical limitations on its use at application levels used by farmers. The market survey showed that the sale price of solid ammonium sulfate fertilizer increased significantly from 1974 at $110/ton to 1998 at $187/ton. Utilities currently pay $16 to $20/ton for the calcium carbonate they use in their flue gas scrubber system. The industries making animal-feed grade calcium supplement pay $30/ton to $67/m-ton for their source of calcium carbonate. Paper, paint, and plastic industries pay as much as $200 to $300/ton for their calcium carbonate filers. The increased sale price of solid ammonium sulfate fertilizer and the possible additional revenue from the sale of the PCC by-product could further improve the economics of producing ammonium sulfate from FGD-gypsum.

  20. Perimbangan Gypsum Bonded Investment terhadap Penysutan Logam Paduan Emas pada Saat Pengecoran

    Ronnie Rusli


    Full Text Available Gypsum bonded investment is usually used for dental gold alloys casting procedure. Casting alloys shrink during solidified from melting temperature to room temperature. In order to obtain an accurate restoration, the shrinkage of the alloy should be compensated by the expansion of the investment at the time of casting procedure. Ideally, the shrinkage of the alloy is equal to the expansion of the investment. However, no investment material fulfills this ideal condition properly. In this paper, how the investment material compensated the shrinkage of the casting alloys will be described briefly.

  1. Constraints from sulfur isotopes on the origin of gypsum at concrete/claystone interfaces

    Lerouge, Catherine; Claret, Francis; Tournassat, Christophe; Grangeon, Sylvain; Gaboreau, Stéphane; Boyer, Bernard; Borschnek, Daniel; Linard, Yannick

    Two in situ concrete/claystone interfaces were sampled at the laboratory level in the Andra Meuse/Haute Marne (France) Underground Research Laboratory (URL) in order to study five years of interactions between Callovian-Oxfordian (COx) claystone and two cementitious materials (concrete bottom slab and shotcrete on the walls of the main gallery), with a specific focus on sulfur. Combined mineralogical, chemical and sulfur isotopic investigations were carried out to define the degree of the perturbation of the sulfur system in the claystone and in both the cementitious materials. At both interfaces, results show that the main perturbation on the claystone side is the formation of scarce μm-sized gypsum, the sulfur content of which is essentially derived from pyrite oxidation. The distribution of gypsum is highly correlated with the fissure network of the damaged zone due to excavation of the gallery. Its presence is also often associated with a loss of cohesion of the concrete/claystone interface. Due to the small amounts of gypsum and its μm-size, measurements were performed by ion microprobe. Adaptations were needed on account of the reactivity of gypsum and sulfates in general under the beam. The use of ion microprobe analysis provided evidence of high local isotopic heterogeneity that could be attributed to kinetic fractionation effects. Some analyses suggest a minor contribution of dissolved sulfates in pore water of claystone and possibly of concrete. The perturbation on the concrete side is marked by a significant increase in the bulk sulfur content within three millimeters of the interface with the claystone, showing a sulfur gradient from claystone to concrete. The main objective of this work was to define the extent of the chemical and mineralogical perturbations, taking into account in situ URL conditions, i.e. hydrodynamic conditions (shotcrete sprayed on the gallery walls and subjected to ventilation of the galleries), damaged zone of claystone induced

  2. Glomalin Production and Microbial Activity in Soils Impacted by Gypsum Mining in a Brazilian Semiarid Area

    Adalia C.E.S. Mergulhao


    Full Text Available Problem statement: Mining activities involve the removal of the vegetal cover and the soil organic layer, causing a severe environmental impact. In Northeast Brazil, 40% of the worlds crude gypsum is found in a semiarid area, making this region responsible for 95% of the gypsum demand in the national market. Although economically important, this activity is harmful to the environment. Studies of soil microbiological and biochemical attributes can help in the identification of the limitations of impacted ecosystems, providing data to define strategies for sustainability of such environments. Approach: To evaluate and compare the biological state of preserved and mining degraded semiarid soils, a native preserved area and areas impacted by gypsum mining were selected at the Araripina Experimental Station, located in the semiarid region of Pernambuco State, Northeast Brazil. The four sampling areas included: (1 A native, preserved �caatinga� area with spine bearing trees and shrubs and some characteristic xerophytic plants (AN; (2 An area surrounding the mine, presenting the same type of vegetation although already degraded (AM; (3 A waste deposit area (AR; (4 Interface area between the waste deposit and a mining degraded area (AI. Samples were taken in each area (1000 m2 during two periods: wet (December/2003, Rainfall = 28.7 mm and dry (September/2004, Rainfall = 1.3 mm. Results: Fluorescein diacetate hydrolysis values, microbial biomass C and basal respiration were higher in the preserved caatinga than in the impacted areas. The gypsum mining activity reduced the concentration of easily extractable glomalin in relation to the native caatinga area in both sampling periods. Higher deposits of total glomalin also occurred in the native area, however, mainly during the wet period. Conclusion: The mining activity produced a negative impact on the soil microbiota, reducing the total enzymatic activity. The microbial

  3. Physical and mechanical characterization of gypsum boards containing phase change materials for latent heat storage

    Oliver-Ramírez, A.


    Full Text Available This article describes the design and manufacture of a gypsum board which, despite its 45 % wt content of phase change materials, meets the minimum physical and mechanical requirements laid down in the legislation on gypsum plasters (Spanish and European standard UNE EN 13279 and Spanish specifications for gypsum acceptance, RY 85. Under this design, a one-metre square, 1.5-cm thick board contains 4.75 kg of PCM, much more than in any prior drylining (the maximum attained to date is 3 kg per m2. The mechanical and physical characteristics of this new composite were previously improved with two joint-action additives: polypropylene fibres and melamine formaldehyde as a dispersing agent. In the 20-30 ºC temperature range, a gypsum board 1.5 cm thick containing this percentage of PCMs can store five times more thermal energy than conventional plasterboard of the same thickness, and the same amount of energy as half-foot hollow brick masonry.

    En esta investigación se ha diseñado y fabricado un panel de escayola que incorpora un 45% en peso de material de cambio de fase, manteniendo las propiedades físicas y mecánicas exigidas en la normativa de aplicación para yesos de construcción (UNE EN 13279 y referencias a la RY 85. Así, un panel de 1,0 m2 y 1,5 cm de espesor, contiene 4,75 kg de PCM, cantidad muy superior a la conseguida hasta la fecha (3 kg/m2. Para ello se ha mejorado previamente sus prestaciones mecánicas y físicas mediante adiciones binarias: fibras de polipropileno y dispersión de melanina formaldehído. Este porcentaje es capaz de almacenar en 1,5 cm de espesor cinco veces la energía térmica de un panel de cartón yeso con el mismo espesor y la misma cantidad que una fábrica de 1/2 pie de ladrillo hueco, en el rango de temperaturas próximas a la de confort (20-30 ºC.

  4. A win/win solution for FGD-gypsum: researches discover beneficial applications for by-product in agriculture

    Ramsier, C.; Norton, D. [AG Spectrum Co. (United States)


    Research at the Ohio State University and the USDA-ARS National Soil Erosion Research Lab at Purdue University has uncovered some viable new reasons for using FGD-gypsum as a regular part of production agriculture. Work has centered on FGD gypsum or calcium sulfite and to a much lesser extent on fly ash. Researchers have found three agronomically valuable functions of these materials. First, and most obvious, is the fertilizer value of these materials. Gypsum applications to the soil surface provide the rainfall with an alternative source of electrolyte which prevents soil crushing, thus keeping the soil open and permeable to rainwater and air. Gypsum is more effective than liming materials atremediation of sub-soil acidity by detoxifying the excess exchangeable aluminium, which causes low pH. One proven way to sequester carbon is to fix it as organic matter in soil. 90% of the carbon in roots is converted to soil organic matter, whereas 90% of surface residue is oxide and the carbon returned to the atmosphere. Therefore, more carbon is sequestered by increasing root growth. Improved soil water management also reduces nitrous oxide emissions from soils. The utility's world is improved since the highest quality and lowest cost material is generated by an emission control scrubber as FGD-gypsum. There are more than 175 million crop acres in the US alone. Each acre would require 0.5 ton per year to prevent surface sealing. This means that the potential for FGD-gypsum use is more than 80 million tons per year. 4 photos.

  5. Biogeochemical oxidation of calcium sulfite hemihydrate to gypsum in flue gas desulfurization byproduct using sulfur-oxidizing bacteria.

    Graves, Duane; Smith, Jacques J; Chen, Linxi; Kreinberg, Allison; Wallace, Brianna; White, Robby


    Flue gas desulfurization (FGD) is a well-established air treatment technology for coal and oil combustion gases that commonly uses lime or pulverized limestone aqueous slurries to precipitate sulfur dioxide (SO2) as crystalline calcium salts. Under forced oxidation (excess oxygen) conditions, FGD byproduct contains almost entirely (>92%) gypsum (CaSO4·2H2O), a useful and marketable commodity. In contrast, FGD byproduct formed in oxygen deficient oxidation systems contains a high percentage of hannebachite (CaSO3·0.5H2O) to yield a material with no commercial value, poor dewatering characteristics, and that is typically disposed in landfills. Hannebachite in FGD byproduct can be chemically converted to gypsum; however, the conditions that support rapid formation of gypsum require large quantities of acids or oxidizers. This work describes a novel, patent pending application of microbial physiology where a natural consortium of sulfur-oxidizing bacteria (SOB) was used to convert hannebachite-enriched FGD byproduct into a commercially valuable, gypsum-enriched product (US Patent Assignment 503373611). To optimize the conversion of hannebachite into gypsum, physiological studies on the SOB were performed to define their growth characteristics. The SOB were found to be aerobic, mesophilic, neutrophilic, and dependent on a ready supply of ammonia. They were capable of converting hannebachite to gypsum at a rate of approximately five percent per day when the culture was applied to a 20 percent FGD byproduct slurry and SOB growth medium. 16S rDNA sequencing revealed that the SOB consortium contained a variety of different bacterial genera including both SOB and sulfate-reducing bacteria. Halothiobacillus, Thiovirga and Thiomonas were the dominant sulfur-oxidizing genera. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Effect of burnout temperature on strength of gypsum-bonded investments.

    Luk, W K; Darvell, B W


    To investigate the variation of the strength of gypsum-bonded dental investments with burnout temperature. The disc-rupture test was employed at burnout temperatures ranging from 450 to 800 degrees C for four products (Beauty Cast, Cristobalite, Novocast (all WhipMix) and Deguvest California (Degussa)). In this test, an investment disc is created inside an investment mold such that it forms a diaphragm across the mold space, being an integral part of the mold. Copper was cast into molds of this type, and whether the disc had ruptured or not was determined by inspection when cold. The amount of copper cast in successive tests was varied in staircase fashion up and down depending on whether the disc survived or failed. The strength of the investment was represented by the 50% point of the transition from survival to rupture. The strength of gypsum-bonded investment is temperature sensitive, there being marked differences between the products tested. Overall, the strength ranking (temperature range average/MPa) was: Cristobalite (10.1)>Beauty Cast (7.8)>Novocast (5.1)>Deguvest California (3.4). The strength ranking at high temperatures differs from that known for the room temperature values. The use by manufacturers of room-temperature strength data conveys no information about high temperature behavior. Investment properties should be optimized by reference to behavior under casting conditions.

  7. Potential Agricultural Uses of Flue Gas Desulfurization Gypsum in the Northern Great Plains

    DeSutter, T.M.; Cihacek, L.J. [North Dakota State University, Fargo, ND (United States). Department of Soil Science


    Flue gas desulfurization gypsum (FGDG) is a byproduct from the combustion of coal for electrical energy production. Currently, FGDG is being produced by 15 electrical generating stations in Alabama, Florida, Indiana, Iowa, Kentucky, Ohio, North Carolina, South Carolina, Tennessee, Texas, and Wisconsin. Much of this byproduct is used in the manufacturing of wallboard. The National Network for Use of FGDG in Agriculture was initiated to explore alternative uses of this byproduct. In the northern Great Plains (North Dakota, South Dakota, and Montana), FGDG has the potential to be used as a Ca or S fertilizer, as an acid soil ameliorant, and for reclaiming or mitigating sodium-affected soils. Greater than 1.4 million Mg of FGDG could initially be used in these states for these purposes. Flue gas desulfurization gypsum can be an agriculturally important resource for helping to increase the usefulness of problem soils and to increase crop and rangeland production. Conducting beneficial use audits would increase the public awareness of this product and help identify to coal combustion electrical generating stations the agriculturally beneficial outlets for this byproduct.


    Daniel Tao


    The objective of this research program is to develop a novel integrated process to eliminate millions of tons of gypsum and pyrite wastes generated annually by the U.S. energy industries and reduce the emission of millions of tons of greenhouse gas carbon dioxide. This was accomplished by converting gypsum and pyrite wastes to marketable products such as lime, direct reduced iron (DRI), and sulfur products and obviating the need to calcine millions of tons of limestone for use in utility scrubbers. Specific objectives included: (1) Develop a novel, integrated process for utilizing two major wastes generated by mining and energy industries to produce lime for recycling and other marketable products. (2) Study individual chemical reactions involved in pyrite decomposition, DRI production, and Muller-Kuhne process for lime regeneration to determine optimum process variables such as temperature, time, and reactant composition. (3) Investigate techniques for effective concentration of pyrite from tailing waste and methods for effective separation of DRI from calcium sulfide.

  9. The production of hydroxyapatite prototypes from solid bodies of Gypsum/Polyvinyl Alcohol composites

    Barbosa, Amanda Alves; Ferraz, Andrea de Vasconcelos; Dantas, Alan Christie; Olivier, Nelson Cardenas, E-mail: [Universidade Federal do Vale do Sao Francisco (UNIVASF), Juazeiro, BA (Brazil)


    Prototypes of porous hydroxyapatite (HAp) were produced from Gypsum/PVA composite, using a mass proportion of 15% polymer. The material was obtained by means of chemical conversion in (NH{sub 4}){sub 2}HPO{sub 4} 0.5 mol.L{sup -1} solution and NH{sub 4}OH 6.0 mol.L{sup -1} alkaline medium for pH control, maintained between 6.0 and 9.0. The reaction occurred at a temperature of 100°C at different test times. The obtained HAp was characterized by several techniques, such as FTIR, which identified the SO{sub 4}{sup 2-} groups characteristic for the Gypsum block, and the PO{sub 4}{sup 2-} groups that are attributed to the biomaterial HAp, besides XRD and SEM, which made it possible to confirm a successful conversion of the material. Tests for mechanical resistance to compression (σ{sub c}) were carried out for both materials as well. (author)

  10. Seepage Analysis of Upper Gotvand Dam Concerning Gypsum Karstification (2D and 3D Approaches)

    Sadrekarimi, Jamshid; Kiyani, Majid; Fakhri, Behnam;


    Upper Gotvand Dam is constructed on the Karun River at the south west of Iran. In this paper, 2D and 3D models of the dam together with the foundation and abutments were established, and several seepage analyses were carried out. Then, the gypsum veins that are scattered throughout the foundation...... ground were included in the models, and the seepage pattern, considering the dissolution law of gypsum, was analyzed. It was disclosed that the discharge fluxes obtained from 2D and 3D analyses are not similar, and the discharge flux in 3D model is about four times that of the 2D model. Also, the 3D...... model locates the phreatic surface somewhat higher than the 2D model. This means that the 2D model estimates lower pore water pressure pattern in comparison with the 3D model. These may be attributed to the fact that with 2D model the lateral components of vectors of seepage velocity are ignored...

  11. Gypsum bonded investment for micro-structure casting of ZnAl4

    Yang Chuang; Li Bangsheng; Ren Mingxing; Fu Hengzhi


    The effects of sintering temperature on the surface roughness of gypsum bonded investments were investigated to find the appropriate sintering temperature applied for micro-investment casting. The surface roughness tests were carried out at sintering temperatures ranging from room temperature to 1,000 ℃for investment compounds mixed from calcium sulphate α-hemihydrate and quartz powder (wt.%, 6:4; 5:5, 4:6, 3:7). In this experiment, each investment compound was prepared by pouring the investment materials into a plastic bottle with the good surface roughness (Ra ~0.2 urn). DTA-TG curves were measured using a thermal analyzer to investigate the difference of surface roughness at different temperatures. The results show that the surface roughness of gypsum bonded investment is temperature sensitive. The preheating temperature of the mold should be up to 600 ℃, but not over 700 ℃, and the investment compound with 60 % plaster and 40 % quartz powder is applicable for preparing the micro-structures. The micro-structures with 100 Mm diameter were produced in the present studies. The results show that the surface roughness of the casting is only Ra ~0.51 urn, slightly rougher than that of the investment mold.

  12. Breakdown development in cover beds, and landscape features induced by intrastratal gypsum karst

    Andrejchuk V.


    Full Text Available Intrastratal karst is by far the predominant gypsum karst type. Its development may begin in deep-seated settings within rocks already buried by younger strata, and it proceeds increasingly rapidly as uplift brings gypsum sequences into progressively shallower positions. Such development commonly occurs under confined (artesian hydrogeological conditions, that subsequently change to open conditions (phreatic-water table-vadose. The general evolutionary line of intrastratal karst is typified by progressive emergence of a sequence into a shallower position, activation of groundwater circulation and development of cave systems within karst units, commencement of gravitational breakdown and its upward propagation through overlying beds, and development of a karst landscape. These processes and phenomena progress through the directed evolution of karst types as follows: deep-seated intrastratal karst (1K to subjacent 1K to entrenched 1K to denuded karst. One of the main characteristics of intrastratal karst is that it induces gravitational breakdown in cover beds. With the aid of processes other then simple breakdown, such effects may propagate upwards and may, or may not, reach the surface, depending upon the thickness and structure of the overburden. A karst landscape evolves when such features reach the surface. This paper considers the conditions and mechanisms of such development.

  13. A Method for Optimizing Lightweight-Gypsum Design Based on Sequential Measurements of Physical Parameters

    Vimmrová, Alena; Kočí, Václav; Krejsová, Jitka; Černý, Robert


    A method for lightweight-gypsum material design using waste stone dust as the foaming agent is described. The main objective is to reach several physical properties which are inversely related in a certain way. Therefore, a linear optimization method is applied to handle this task systematically. The optimization process is based on sequential measurement of physical properties. The results are subsequently point-awarded according to a complex point criterion and new composition is proposed. After 17 trials the final mixture is obtained, having the bulk density equal to (586 ± 19) kg/m3 and compressive strength (1.10 ± 0.07) MPa. According to a detailed comparative analysis with reference gypsum, the newly developed material can be used as excellent thermally insulating interior plaster with the thermal conductivity of (0.082 ± 0.005) W/(m·K). In addition, its practical application can bring substantial economic and environmental benefits as the material contains 25 % of waste stone dust.

  14. Crystallisation of Gypsum and Prevention of Foaming in Wet Flue Gas Desulphurisation (FGD) Plants

    Hansen, Brian Brun

    of reliability of operation and consistency of the gypsum quality obtained. This work may furthermore be of interest to other industrial systems in which foaming or gypsum crystallisation may take place. FGD is an industrial process, which removes sulphur dioxide (SO2) from flue gasses generated by fossil fuel...... combustion at power plants and other heavy industries, thereby abating the detrimental effects known as “acid rain”. The majority of the 680 FGD-plants installed at power plants worldwide in 1999 (2.41•105 MWe) were using the wet FGD-technology. This process absorbs ~ 99 % of the SO2 by an alkaline slurry....... Experiments in a falling film wet FGD pilot plant have shown a strong non-linear behaviour (in a ln(n(l)) vs. l plot) at the lower end of the particle size range, compared to the well-known linear “mixed suspension mixed product removal (MSMPR)” model. A transient population balance model, fitted...

  15. Investigation of Dynamic Crack Coalescence Using a Gypsum-Like 3D Printing Material

    Jiang, Chao; Zhao, Gao-Feng; Zhu, Jianbo; Zhao, Yi-Xin; Shen, Luming


    Dynamic crack coalescence attracts great attention in rock mechanics. However, specimen preparation in experimental study is a time-consuming and difficult procedure. In this work, a gypsum-like material by powder bed and inkjet 3D printing technique was applied to produce specimens with preset cracks for split Hopkinson pressure bar (SHPB) test. From micro X-ray CT test, it was found that the 3D printing technique could successfully prepare specimens that contain preset cracks with width of 0.2 mm. Basic mechanical properties of the 3D printing material, i.e., the elastic modulus, the Poisson's ratio, the density, the compressive strength, the indirect tensile strength, and the fracture toughness, were obtained and reported. Unlike 3D printed specimens using polylactic acid, these gypsum-like specimens can produce failure patterns much closer to those observed in classical rock mechanical tests. Finally, the dynamic crack coalescence of the 3D printed specimens with preset cracks were captured using a high-speed camera during SHPB tests. Failure patterns of these 3D printed specimens are similar to the specimens made by Portland cement concrete. Our results indicate that sample preparation by 3D printing is highly competitive due to its quickness in prototyping, precision and flexibility on the geometry, and high material homogeneity.

  16. Experimental Study of Stabilized Soil Utilizing Circulating Fluidized Bed Combustion Desulfurization Ash with Carbide Slag and Desulfurization Gypsum


    This paper discusses the feasibility of preparing soil stabilizer which is circulating fluidized bed combustion ash-based, supplemented with carbide slag and desulfurization gypsum, composed entirely of complete industrial wastes. The results show that CFBC ash has better pozzolanic activity than fly ash. When stabilizer total content is 10% and the ratio of CFBC ash : carbide slag : desulfurization gypsum is 7.2 : 1.8 : 1, compressive strength of stabilized soil can reach the maximum of 2.12...

  17. Gypsum-based biomaterials: Evaluation of physical and mechanical properties, cellular effects and its potential as a pulp liner.

    Low, Amy; Mohd Yusof, Hamidah; Reza, Fazal; Abdullah Nurul, Asma; Sritharan, Shaminea; Haania Zain Ali, Niswathul; Subhi Azeez, Hasan; Husein, Adam


    This in vitro study aimed to evaluate setting time and compressive strength of gypsum-based chitosan biomaterials and its effect on proliferation of stem cells from human exfoliated deciduous teeth (SHED) and alkaline phosphatase (ALP) activity. Pure-GYP was mixed with water (2.5 g: 1.9 mL); Gyp-CHT was prepared with gypsum, chitosan, and water (2.5 g: 0.285 g: 1.9 mL). Cell viability and ALP activity were assessed at different periods. Data were analyzed using SPSS (pbiomaterials for its pulp protective potentialities.

  18. Populations of some molds in water-damaged homes may differ if the home was constructed with gypsum drywall compared to plaster

    Starting in the 1940s, gypsum drywall began replacing plaster and lathe in the U.S. home construction industry. Our goal was to evaluate whether some mold populations differ in water- damaged homes primarily constructed with gypsum drywall compared to plaster. The dust samples fr...

  19. Populations of some molds in water-damaged homes may differ if the home was constructed with gypsum drywall compared to plaster

    Starting in the 1940s, gypsum drywall began replacing plaster and lathe in the U.S. home construction industry. Our goal was to evaluate whether some mold populations differ in water- damaged homes primarily constructed with gypsum drywall compared to plaster. The dust samples fr...

  20. Evaluating the fate of mercury and other metals across the life-cycle stages from the use of FGD gypsum for wallboard production

    In 2007, 12.3 million tons of flue gas desulfurization (FGD) gypsum was produced due to air emission controls at coal-fired power plants. With increasing use of wet scrubbers in response to more stringent air pollution control requirements, FGD gypsum production is expected to in...

  1. Simultaneous determination of lfuorine and chlorine in gypsum and gypsum products by ion chromatography%离子色谱法同时测定石膏及石膏制品中的氟和氯

    徐丹华; 梅一飞; 刘实华


    建立了离子色谱法同时测定石膏及石膏制品中氟和氯的方法。实验结果表明:采用离子色谱法一次进样可准确测定石膏及石膏制品中的氟和氯的含量。流动相采用20/30mM KOH溶液,流速为0.8/1.0mL/min。方法有较好的准确度和回收率。%Method to establish the ion chromatography method for the simultaneous determination of fluoride and chloride in gypsum and gypsum products.The experimental results show that: Using ion chromatography can be accurate determination of fluorine and chlorine in gypsum and gypsum products.The mobile phase is the 20/30mM KOH solution,the flow rate was 0.8/1.0mL/min. Method has better accuracy and recovery rate.

  2. Lipid and Phylogenetic Analysis of a Gypsum-hosted Endoevaporitic Microbial Community

    Turk, K. A.; Jahnke, L. L.; Green, S. J.; Kubo, M. D.; Vogel, M. B.; Des Marais, D. J.


    Gypsum evaporites host diverse, productive and volumetrically significant microbial communities and are relevant modern-day analogs to both Precambrian sabkha deposits and, potentially, Martian evaporites. Extensive evaporites form in subaqueous environments of high salinity ponds (>150 permil) maintained by the Exportadora de Sal, S. A. (ESSA) in Guerrero Negro, B.C.S., Mexico. A gypsarenite (reworked clastic gypsum) crust found along the southeast margin of ESSA's Pond 9 was collected in February 2004 and each vibrantly colored layer in the top centimeter was sampled. Extant microbial communities from each layer were characterized using complementary culture-independent molecular techniques, lipid biomarker analysis, and compound specific isotopic analysis. Coupling molecular analysis with lipid biomarker analysis revealed that oxygenic photosynthetic organisms dominate the surface layers (top 3 mm). Polar lipids from the surface layers consisted predominantly of glycolipids, which are characteristic of algae, cyanobacteria and green anoxygenic photosynthetic bacteria. Consistent with prior analyses of gypsum evaporites, 16S rRNA gene clone libraries indicate that cyanobacterial populations belong primarily to the genus Cyanothece. The bacterial community below the surface layers is more diverse and dominated by anaerobic organisms. Phototrophic purple sulfur bacteria, sulfate-reducing bacteria (SRB), and Bacteroidetes were particularly abundant. The relative abundances of SRB increased with depth; Desulfobacteraceae clones were distributed throughout the crust, but not at the surface, while Desulfovibrionaceae clones were found predominantly in the deepest layers. These molecular results are consistent with fatty acid biomarker analysis. δ13C values of major lipid classes in the crust and sediment range from 14 to 36‰, which is considerably lower than corresponding values for benthic Microcoleus-dominated cyanobacterial mats found at lower salinities at ESSA

  3. Permeability control on transient slip weakening during gypsum dehydration: Implications for earthquakes in subduction zones

    Leclère, Henri; Faulkner, Daniel; Wheeler, John; Mariani, Elisabetta


    A conflict has emerged from recent laboratory experiments regarding the question of whether or not dehydration reactions can promote unstable slip in subduction zones leading to earthquakes. Although reactions produce mechanical weakening due to pore-fluid pressure increase, this weakening has been associated with both stable and unstable slip. Here, new results monitoring strength, permeability, pore-fluid pressure, reaction progress and microstructural evolution during dehydration reactions are presented to identify the conditions necessary for mechanical instability. Triaxial experiments are conducted using gypsum and a direct shear sample assembly with constant normal stress that allows the measurement of permeability during sliding. Tests are conducted with temperature ramp from 70 to 150 °C and with different effective confining pressures (50, 100 and 150 MPa) and velocities (0.1 and 0.4 μm s-1). Results show that gypsum dehydration to bassanite induces transient stable-slip weakening that is controlled by pore-fluid pressure and permeability evolution. At the onset of dehydration, the low permeability promoted by pore compaction induces pore-fluid pressure build-up and stable slip weakening. The increase of bassanite content during the reaction shows clear evidence of dehydration related with the development of R1 Riedel shears and P foliation planes where bassanite is preferentially localized along these structures. The continued production of bassanite, which is stronger than gypsum, provides a supporting framework for newly formed pores, thus resulting in permeability increase, pore-fluid pressure drop and fault strength increase. After dehydration reaction, deformation is characterized by unstable slip on the fully dehydrated reaction product, controlled by the transition from velocity-strengthening to velocity-weakening behaviour of bassanite at temperature above ∼140 °C and the localization of deformation along narrow Y-shear planes. This study

  4. Preparation of pure calcium carbonate by mineral carbonation using industrial byproduct FGD gypsum

    Song, K.; Kim, W.; Bang, J. H.; Park, S.; Jeon, C. W.


    Mineral carbonation is one of the geological approaches for the sequestration of anthropogenic CO2 gas. Its concept is based on the natural weathering processes in which silicate minerals containing divalent cations such as Ca or Mg are carbonated to CaCO3 or MgCO3 in the reaction with CO2gas. Raw materials for the mineral carbonation have been extended to various industrial solid wastes such as steel slag, ashes, or FGD (flue gas desulfurization) gypsum which are rich in divalent cations. These materials have economic advantages when they are produced in CO2 emission sites. Flue gas desulfurization (FGD) gypsum is such a byproduct obtained in at coal-fired power plants. Recently, we carried out a research on the direct mineral carbonation of FGD gypsum for CO2sequestration. It showed high carbonation reactivity under ambient conditions and the process can be described as follows: CaSO4·2H2O + CO2(g) + 2NH4OH(aq) → CaCO3(s) + (NH4)2SO4(aq) (1) At the early stage of the process, calcium carbonate (CaCO3) exists as a dissolved ion pair during the induction period. High-purity CaCO3 could be precipitated from dissolved calcium carbonate solution extracted during the induction period. The effect of experimental parameters on pure CaCO3 was evaluated: CO2 flow rate (1-3 L/min), ammonia content (4-12%), and solid-to-liquid (S/L) ratio (5-300 g/L). FE-SEM (field-emission scanning electron microscopy) and XRD (X-ray diffraction) study revealed that the precipitated CaCO3 was round-shaped vaterite crystals. The induction time was inversely proportional to the CO2 flow rate and the yield for pure CaCO3 increased with the ammonia content. The formation efficiency for pure CaCO3 decreased with S/L (solid/liquid) ratio. It was 90% (mol/mol) when the S/L ratio was 5 g/L. However, S/L ratio didn't affect the maximum solubility limit of dissolved CaCO3.

  5. Influence of gypsum on efflorescence in ceramic tiles; Influence da gipsita no surgimento de eflorescencia em telhas ceramicas

    Monteiro, C.M.O.L. [Servico Nacional de Aprendizagem Industrial (SENAI), Teresina, PI (Brazil); Nascimento, R.M.; Martinelli, A.E. [Universidade Federal do Rio Grande do Norte (PPgCEM/UFRN), Natal, RN (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais


    The red ceramic industry is recognized as of major importance in Piaui State. The State capital, Teresina, is the greatest producer of this material, which is used mainly for masonry sealing blocks. One of the most frequent problems in this kind of products is the efflorescence.This paper has the main objective of studying the influence of gypsum on tiles, using the local industry production standards. The raw materials were characterized by FRX, DRX, thermal analysis and sulfates. Extruded test specimens were made with the addition of 1%, 3% and 5% of gypsum in the ceramic paste, burned at 850 deg C, 950 deg C and 1050 deg C and submitted to further technological and analysis for MEV. The reference ceramic paste did not show tendency to efflorescence formation after burning for samples with 1% gypsum added to the paste. The reference ceramic paste showed tendency to efflorescence formation after drying and consolidated efflorescence after burning for samples with 5% gypsum added to the paste. (author)

  6. Gypsum (CaSO42H2O) scaling on polybenzimidazole and cellulose acetate hollow fiber membranes under forward osmosis

    Chen, Si Cong


    We have examined the gypsum (CaSO42H2O) scaling phenomena on membranes with different physicochemical properties in forward osmosis (FO) processes. Three hollow fiber membranes made of (1) cellulose acetate (CA), (2) polybenzimidazole (PBI)/polyethersulfone (PES) and (3) PBI-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) were studied. For the first time in FO processes, we have found that surface ionic interactions dominate gypsum scaling on the membrane surface. A 70% flux reduction was observed on negatively charged CA and PBI membrane surfaces, due to strong attractive forces. The PBI membrane surface also showed a slightly positive charge at a low pH value of 3 and exhibited a 30% flux reduction. The atomic force microscopy (AFM) force measurements confirmed a strong repulsive force between gypsum and PBI at a pH value of 3. The newly developed PBI-POSS/PAN membrane had ridge morphology and a contact angle of 51.42 14.85 after the addition of hydrophilic POSS nanoparticles and 3 min thermal treatment at 95 C. Minimal scaling and an only 1.3% flux reduction were observed at a pH value of 3. Such a ridge structure may reduce scaling by not providing a locally flat surface to the crystallite at a pH value of 3; thus, gypsum would be easily washed away from the surface. 2013 by the authors; licensee MDPI, Basel, Switzerland.

  7. Flue-Gas Desulfurization Gypsum Effects on Urea-Degrading Bacteria and Ammonia Volatilization From Broiler Litter

    A major concern of the broiler industry is the volatilization of ammonia (NH3) from the mixture of bedding material and broiler excretion that covers the floor of broiler houses. Gypsum has been proposed as a litter amendment to reduce NH3 volatilization, but reports of NH3 abatement vary among stu...

  8. Three annual flue gas desulfurization gypsum applications on macronutrient and micronutrient losses in runoff from bermudagrass fertilized with poultry litter

    Considerable amounts of flue gas desulfurization (FGD) gypsum are being produced as a by-product of generating electricity. As a result, beneficial reuse of this by-product is being sought to reduce landfilling and its associated cost. The use of this byproduct as a low-cost soil amendment for suppl...

  9. Characterization of gypsum crystals exposed to a high CO{sub 2} concentration fog using x-ray

    Carreño-Márquez, I. J. A.; Castillo-Sandoval, I.; Esparza-Ponce, H. E.; Fuentes-Cobas, L.; Montero-Cabrera, M. E., E-mail: [Centro de Investigación en Materiales Avanzados (CIMAV), Miguel de Cervantes 120, Chihuahua, Chih. 31136 (Mexico)


    In Chihuahua State, a little town called Naica has the largest gypsum single crystals in the world. The growth of these structures has been described as a long and stable process developed over thousands of years. Due to the change in the environmental conditions, these crystals could suffer alterations on their surface. In this project we study the cause of possible deterioration of the giant crystals and intend to suggest measures for their preservation. For this sake, our first experiment consists on several gypsum crystals that have been subjected in a climate chamber to a fog at high CO{sub 2} concentration and 51 °C for a period of time of six months, extracting two crystals every 15 days. Then the crystals have been characterized through Grazing Incidence X-Ray Diffraction using a diffractometer PanAlytical X’PertPro with two different detectors; Xe-filled proportional detector and a Pixel 3D detector. The results were compared to determine which technique is the most suitable to study the degradation of gypsum single crystals. In the two cases, we have identified only the gypsum phase, but with different crystal plane orientations.

  10. Effect of Ammonium Chloride Solution on the Growth of Phosphorus Gypsum Whisker and Its Modification

    Shouwei Jian


    Full Text Available Phosphogypsum is the by-product of phosphate of fertilizer or phosphate which causes serious environmental pollution. In this work, a series of phosphogypsum whiskers were prepared using phosphogypsum as raw materials and NH4Cl as additive through the atmospheric water solution method. The results showed that the ammonium chloride solution has a great influence on phosphogypsum whiskers growth and the solubility. The best whisker aspect ratio of phosphogypsum was preferred in 1 mol/L NH4Cl solution, in which the solubility achieved 6.434 mg/mL and the aspect ratio reached 69.29. Besides, NH4Cl was found to have a modified effect on gypsum whiskers’ growth and it can be used to get mesh or dendritic whiskers.

  11. Age and speleogenesis of epigenic gypsum caves in the northern Apennines (Italy)

    Columbu, Andrea; Chiarini, Veronica; De Waele, Jo; Drysdale, Russell; Forti, Paolo; Hellstrom, John; Woodhead, Jon


    Triassic and Messinian gypsum beds host the majority of the caves in the eastern flank of the northern Apennines. To date, more than six hundreds voids have been mapped, including the longest known epigenic gypsum cave system in the world (Spipola-Acquafredda, ~11 km of tunnels) (De Waele et al., 2013). Superimposed caves are typically sub-horizontal (Klimchouk, 2000) and connected through vertical shafts, reflecting the palaeo base-level variations. When preserved, river terraces at the surface lie at the same palaeo altitude of the base level and horizontal cave passages. Notwithstanding the well-known geology of the area known (Vai and Martini, 2001), the age of these caves has been greatly underestimated in the past. Considering the rapid dissolution of the gypsum and uplifting of the area, the start of speleogenesis activity was considered to have occurred during the last glacial age. The age of karst voids can be only indirectly estimated by the dating of the infilling sediments. U-Th dating on carbonate speleothems provides high-precision and accurate ages (Hellstrom, 2003; Scholz and Hoffmann, 2008). We thus applied this methodology to 20 speleothems coming from 14 different caves belonging to the Monte Tondo, Spipola Acquafredda, Castelnuovo, Stella-Rio Basino and Brisighella systems. The results show that: i) caves were forming since at least ~300 ka; ii) the peak of speleogenesis was reached during relatively cold climate stages, when rivers formed terraces at the surface and aggradation caused paragenesis in the stable cave levels (Columbu et al., 2015). Besides the significant contribution to the understanding of the Apennines evaporite karst evolution, this study (and its further advancement) may also refine knowledge of the local vs regional uplifting rates and base-level variations since the late Pleistocene (Wegmann and Pazzaglia, 2009). References Columbu, A., De Waele, J., Forti, P., Montagna, P., Picotti, V., Pons-Branchu, E., Hellstrom, J

  12. SO/sub 2/ scrubbing downstream of combustion systems with raw gypsum as final product

    Hoelter, H.; Igelbuescher, H.; Gresch, H.; Dewert, H.


    This flue gas purification method first purifies the crude gas from HCl and HF in the prescrubber and from SO/sub 2/ and/or NO/sub x/ in the main scrubber. The CaSO/sub 3//CaSO/sub 4/ product occurring in the main scrubber is, according to the invention, pumped through a pipe into the prescrubber. In this process a well-oxidized CaSO/sub 4/ product with adequate content of calcium chloride develops in the scrubber liquid because of the high quantity of excess atmospheric oxygen in the crude gas. In this way raw gypsum is enriched by chlorides and can be directly used as building material, e.g. in mines. Thus, the salt load in the prescrubber is reduced.

  13. Calibration of a hysteretic model for glass fiber reinforced gypsum wall panels

    Janardhana, Maganti; Robin Davis, P.; Ravichandran, S. S.; Prasad, A. M.; Menon, D.


    Glass fiber reinforced gypsum (GFRG) wall panels are prefabricated panels with hollow cores, originally developed in Australia and subsequently adopted by India and China for use in buildings. This paper discusses identification and calibration of a suitable hysteretic model for GFRG wall panels filled with reinforced concrete. As considerable pinching was observed in the experimental results, a suitable hysteretic model with pinched hysteretic rule is used to conduct a series of quasi-static as inelastic hysteretic response analyses of GFRG panels with two different widths. The calibration of the pinching model parameters was carried out to approximately match the simulated and experimental responses up to 80% of the peak load in the post peak region. Interestingly, the same values of various parameters (energy dissipation and pinching related parameters) were obtained for all five test specimens.

  14. Some aspects on improvement of water resistant perfornace of gypsum binders

    Fomina Ekaterina


    Full Text Available The study reports that control of water resistant and strength performance of composite binder can be accomplished by using nanostructured gypsum silicate binder and portland cement and reduction of calcium sulfate dihydrate. Formation of an arranged more dense packing in crystal matrix of binder structure can be achieved through polydispersity of nanostructured silicon component. Highly reactive silica particles participate in synthesis of microcrystalline compounds such as hydroxylellestadite and serve as nucleation sites providing an increase of surface contact area between crystal structures. Cement in the system provides conditions to synthesis of stable flat-like hydroxysulfoaluminates. Upon hydration of a binder crystals of calcium sulfate dihydrate impound to a mass of water resistant crystalhydrate new formations, type and morphology of which promotes decreasing of intercrystal porosity followed by density, strength and water resistance increase of the composite.

  15. Effect Of Coir Fibres On The Compaction And Unconfined Compressive Strength Of Bentonite-Lime-Gypsum Mixture

    Tilak B. Vidya


    Full Text Available This paper presents the effect of coir fibres on the compaction and unconfined compressive strength of a bentonite-lime-gypsum mixture. The coir fiber content varied from 0.5 to 2 %. The results indicated that the dry unit weight and the optimum moisture content of a bentonite – lime mix increased with the addition of gypsum. The unconfined compressive strength of the bentonite increased with the increase in the lime content up to 8 %. Beyond 8 %, the unconfined compressive strength decreased. The dry unit weight of the reference mix decreased, and the optimum moisture content increased with the addition of coir fibre. The unconfined compressive strength of the bentonite + 8 % lime mix increased up to 4 % with the gypsum. Beyond 4 %, the unconfined compressive strength decreased. The unconfined compressive strength of the reference mix increased with the addition of coir fibre up to a fibre content of 1.5 %. The unconfined compressive strength of the reference mix-coir fibre composite was less in comparison to the reference mix. The unconfined compressive strength of the bentonite increased with the addition of lime and gypsum and with the increase in the curing period. The improvement in the post-peak region was better for the reference mix with reinforced coir fibres as compared to the unreinforced reference mix. The improved post-peak behaviour of the bentonite-lime-gypsum-coir fibre mixture could boost the construction of temporary roads on such problematic soils. Further, its use will also provide an environmental motivation for providing a means of consuming large quantities of coir fibres.

  16. Hydration effects on gypsum dissolution revealed by in situ nanoscale atomic force microscopy observations

    Burgos-Cara, A.; Putnis, C. V.; Rodriguez-Navarro, C.; Ruiz-Agudo, E.


    Recent work has suggested that the rates of mineral dissolution in aqueous solutions are dependent on the kinetics of dehydration of the ions building the crystal. Dehydration kinetics will be ultimately determined by the competition between ion-water and water-water interactions, which can be significantly modified by the presence of background ions in solution. At low ionic strength, the effect of electrolytes on ion-water (electrostatic) interactions will dominate (Kowacz et al., 2007). By performing macroscopic and in situ, microscopic (atomic force microscopy) dissolution experiments, the effect of background electrolytes on the dissolution kinetics of gypsum (CaSO4·2H2O) {0 1 0} cleavage surfaces is tested at constant, low ionic strength (IS = 0.05) and undersaturation (saturation index, SI = -0.045). Dissolution rates are systematically lower in the presence of 1:1 background electrolytes than in an electrolyte-free solution, regardless of the nature of the electrolyte tested. We hypothesize that stabilization of the hydration shell of calcium by the presence of background ions can explain this result, based on the observed correlations in dissolution rates with the ionic surface tension increment of the background ion in solution. Stabilization of the cation hydration shell should favor dissolution. However, in the case of strongly hydrated ions such as Ca2+, this has a direct entropic effect that reduces the overall ΔG of the system, so that dissolution is energetically less favorable. Overall, these results provide new evidence that supports cation dehydration being the rate-controlling step for gypsum dissolution, as proposed for other minerals such as barite, dolomite and calcite.

  17. Carbon and sulfur cycling by microbial communities in a gypsum-treated oil sands tailings pond.

    Ramos-Padrón, Esther; Bordenave, Sylvain; Lin, Shiping; Bhaskar, Iyswarya Mani; Dong, Xiaoli; Sensen, Christoph W; Fournier, Joseph; Voordouw, Gerrit; Gieg, Lisa M


    Oil sands tailings ponds receive and store the solid and liquid waste from bitumen extraction and are managed to promote solids densification and water recycling. The ponds are highly stratified due to increasing solids content as a function of depth but can be impacted by tailings addition and removal and by convection due to microbial gas production. We characterized the microbial communities in relation to microbial activities as a function of depth in an active tailings pond routinely treated with gypsum (CaSO(4)·2H(2)O) to accelerate densification. Pyrosequencing of 16S rDNA gene sequences indicated that the aerobic surface layer, where the highest level of sulfate (6 mM) but no sulfide was detected, had a very different community profile than the rest of the pond. Deeper anaerobic layers were dominated by syntrophs (Pelotomaculum, Syntrophus, and Smithella spp.), sulfate- and sulfur-reducing bacteria (SRB, Desulfocapsa and Desulfurivibrio spp.), acetate- and H(2)-using methanogens, and a variety of other anaerobes that have been implicated in hydrocarbon utilization or iron and sulfur cycling. The SRB were most abundant from 10 to 14 mbs, bracketing the zone where the sulfate reduction rate was highest. Similarly, the most abundant methanogens and syntrophs identified as a function of depth closely mirrored the fluctuating methanogenesis rates. Methanogenesis was inhibited in laboratory incubations by nearly 50% when sulfate was supplied at pond-level concentrations suggesting that in situ sulfate reduction can substantially minimize methane emissions. Based on our data, we hypothesize that the emission of sulfide due to SRB activity in the gypsum treated pond is also limited due to its high solubility and oxidation in surface waters.

  18. Analysis of naturally-occurring radionuclides in coal combustion fly ash, gypsum, and scrubber residue samples.

    Roper, Angela R; Stabin, Michael G; Delapp, Rossane C; Kosson, David S


    Coal combustion residues from coal-fired power plants can be advantageous for use in building and construction materials. These by-products contain trace quantities of naturally occurring radionuclides from the uranium and thorium series, as well as other naturally occurring radionuclides such as K. Analysis was performed on samples of coal fly ash, flue gas desulfurization, gypsum and scrubber sludges, fixated scrubber sludges, and waste water filter cakes sampled from multiple coal-fired power plants in the United States. The radioactive content of U and Th decay series nuclides was determined using gamma photopeaks from progeny Pb at 352 keV and Tl at 583 keV, respectively; K specific activities were determined using the 1,461 keV photopeak. The samples were hermetically sealed to allow for secular equilibrium between the radium parents and the radon and subsequent progeny. Samples were analyzed in a common geometry using two high purity germanium photon detectors with low energy detection capabilities. The specific activities (Bq kg) were compared to results from literature studies including different building materials and fly ash specific activities. Fly ash from bituminous and subbituminous coals had U specific activities varying from 30-217 Bq kg (mean + 1 s.d. 119 ± 45 Bq kg) and 72-209 Bq kg (115 ± 40 Bq kg), respectively; Th specific activities from 10-120 Bq kg (73 ± 26 Bq kg) and 53-110 Bq kg (81 ± 18 Bq kg), respectively; and K specific activities from 177 to 928 Bq kg (569 ± 184 Bq kg) and 87-303 Bq kg (171 ± 69 Bq kg), respectively. Gypsum samples had U, Th, and K specific activities approximately one order of magnitude less than measured for fly ash samples.

  19. Seasonal variation of gypsum in aerosol and its effect on the acidity of wet precipitation on the Japan sea side of Japan

    Zhou, Guoping; Tazaki, Kazue

    Variations of mineral concentrations in aerosols collected weekly for a 1 yr period (from October 1992 to September 1993) on Matsue, Shimane Prefecture, Japan, were investigated by X-ray powder diffraction (XRD) analysis. Major elemental concentrations were measured by energy dispersive X-ray analysis (EDX). Sulfate minerals in aerosol include gypsum, ferricopiapite, metavoltine and glauberite. Gypsum showed two high concentration peaks during spring and early winter, which was consistent with that of clay minerals and quartz. The ratios of gypsum to clay minerals, quartz and calcite, respectively, showed an increase of gypsum in spring. A non-agreement of concentration distribution between calcite and other soil minerals during spring implies a conversion of calcite to gypsum during transport. Individual particle analyses by EDX revealed large amounts of S-rich submicrometer particles coated on the surface of minerals. A sequence favorable to be attached by S constituents was calcite (83%) > clay minerals (68%) > fly ash (55) > quartz and feldspars (36%) The reaction between calcite and simulated acid rain solution with pHs of 3, 4 and 5 showed a formation of gypsum in 12 h, indicating that the conversion of calcite to gypsum is possible in the presence of sulfuric acid or (NH 4) 2 SO 4 aerosols during transport from the Asian continent to the Japan Islands.

  20. A biological process for the reclamation of flue gas desulfurization gypsum using mixed sulfate-reducing bacteria with inexpensive carbon sources.

    Kaufman, E N; Little, M H; Selvaraj, P


    A combined chemical and biological process for the recycling of flue gas desulfurization (FGD) gypsum into calcium carbonate and elemental sulfur is demonstrated. In this process, a mixed culture of sulfate-reducing bacteria (SRB) utilizes inexpensive carbon sources, such as sewage digest or synthesis gas, to reduce FGD gypsum to hydrogen sulfide. The sulfide is then oxidized to elemental sulfur via reaction with ferric sulfate, and accumulating calcium ions are precipitated as calcium carbonate using carbon dioxide. Employing anaerobically digested municipal sewage sludge (AD-MSS) medium as a carbon source, SRBs in serum bottles demonstrated an FGD gypsum reduction rate of 8 mg/L/h (10(9) cells)(-1). A chemostat with continuous addition of both AD-MSS media and gypsum exhibited sulfate reduction rates as high as 1.3 kg FGD gypsum/m(3)d. The increased biocatalyst density afforded by cell immobilization in a columnar reactor allowed a productivity of 152 mg SO(4) (-2)/Lh or 6.6 kg FGD gypsum/m(3)d. Both reactors demonstrated 100% conversion of sulfate, with 75-100% recovery of elemental sulfur and chemical oxygen demand utilization as high as 70%. Calcium carbonate was recovered from the reactor effluent on precipitation using carbon dioxide. It was demonstrated that SRBs may also use synthesis gas (CO, H(2), and CO(2) in the reduction of gypsum, further decreasing process costs. The formation of two marketable products-elemental sulfur and calcium carbonate-from FGD gypsum sludge, combined with the use of a low-cost carbon source and further improvements in reactor design, promises to offer an attractive alternative to the landfilling of FGD gypsum.

  1. VNIR reflectance spectra of gypsum mixtures for comparison with White Sands National Monument, New Mexico (WSNM) dune samples as an analog study of the Olympia Undae region of Mars

    King, S. J.; Bishop, J. L.; Fenton, L. K.; Lafuente, B.; Garcia, G. C.; Horgan, B. H.


    Dunes at WSNM are being used as an analog study area for gypsum-rich dunes near the northern polar region of Mars. Samples were collected from 4 dunes at WSNM for this study. In order to determine abundances of the gypsum, quartz and dolomite present in the dune sand, size separates (250 μm) were prepared for gypsum, quartz and dolomite, mixtures were prepared using the 90-150 μm size fraction, and all samples were characterized in the lab. Analyses of the VNIR spectral data are presented here (Figs. 1-2) and analyses of the XRD data are presented in a companion abstract [1]. The majority of the dune sand is dominated by gypsum, while the coarse grains at some ripples are largely dolomite. Mid-IR spectra will be evaluated as well. Gypsum/Dolomite Mixtures (Fig. 1) There is a clear progression of albedo and band strength in these mixture spectra as one mineral is increased and the other decreased. The mixture spectra are dominated by the gypsum bands for mixtures that are gypsum rich (≥50wt.% gypsum) including a triplet at 1.446-1.535 μm, plus bands at 1.749, 1.945, 2.217 and 2.267 μm. When mixtures become predominantly dolomite (10/90 & 20/80 mixtures), the gypsum bands are significantly weaker, while the dolomite band at 2.322 becomes much more visible. Gypsum/Quartz Mixtures (Fig. 2) The gypsum/quartz mixture spectra are dominated to an even greater extent by gypsum, resulting in readily observable gypsum features for spectra of samples with only 10 wt.% gypsum. [1] Lafuente et al. (2013) AGU, submitted.

  2. Origin and diagenetic evolution of gypsum and microbialitic carbonates in the Late Sag of the Namibe Basin (SW Angola)

    Laurent, Gindre-Chanu; Edoardo, Perri; Ian, Sharp R.; Peacock, D. C. P.; Roger, Swart; Ragnar, Poulsen; Hercinda, Ferreira; Vladimir, Machado


    Ephemeral evaporitic conditions developed within the uppermost part of the transgressive Late Sag sequence in the Namibe Basin (SW Angola), leading to the formation of extensive centimetre- to metre-thick sulphate-bearing deposits and correlative microbialitic carbonates rich in pseudomorphs after evaporite crystals. The onshore pre-salt beds examined in this study are located up to 25 m underneath the major mid-Aptian evaporitic succession, which is typified at the outcrop by gypsiferous Bambata Formation and in the subsurface by the halite-dominated Loeme Formation. Carbonate-evaporite cycles mostly occur at the top of metre-thick regressive parasequences, which progressively onlap and overstep landward the former faulted (rift) topography, or fill major pre-salt palaeo-valleys. The sulphate beds are made up of alabastrine gypsum associated with embedded botryoidal nodules, dissolution-related gypsum breccia, and are cross-cut by thin satin-spar gypsum veins. Nodular and fine-grained fabrics are interpreted as being diagenetic gypsum deposits resulting from the dissolution and recrystallisation of former depositional subaqueous sulphates, whereas gypsum veins and breccia result from telogenetic processes. The carbonates display a broader diversity of facies, characterised by rapid lateral variations along strike. Thin dolomitic and calcitic bacterial-mediated filamentous microbialitic boundstones enclose a broad variety of evaporite pseudomorphs and can pass laterally over a few metres into sulphate beds. Dissolution-related depositional breccias are also common and indicate early dissolution of former evaporite layers embedded within the microbialites. Sulphate and carbonate units are interpreted as being concomitantly deposited along a tide-dominated coastal supra- to intertidal- sabkha and constitute high-frequency hypersaline precursor events, prior to the accumulation of the giant saline mid-Aptian Bambata and Loeme Formations. Petrographic and geochemical

  3. Study of the Effect of Gypsum and Rice Straw Extract on the Control of Earthy-Musty Odor in Tilapia Culture Pond

    Supannee SUWANPAKDEE


    Full Text Available The effect of gypsum and rice straw extract to reduce the levels of earthy-musty odor in tilapia earthen ponds was determined. Three treatments with 3 replicates in a completely randomized design were performed as follows: T1 - control; T2 - gypsum at 200 ppm, and T3 - rice straw tannin extract at 1 ppm. The results show that rice straw tannin extract treatment in tilapia ponds was the most effective method in reducing off-flavor in pond water. The use of 200 ppm gypsum in reducing off-flavor in ponds was also more effective than the control. Both rice straw extract and gypsum-treated ponds had increased fish biomass and %FCE. These methods have potential as alternative methods for the reduction of off-flavor, as well as the control of phytoplankton, turbidity, and TSS in tilapia ponds.

  4. Experimental Study of Stabilized Soil Utilizing Circulating Fluidized Bed Combustion Desulfurization Ash with Carbide Slag and Desulfurization Gypsum

    Dezhi Shao


    Full Text Available This paper discusses the feasibility of preparing soil stabilizer which is circulating fluidized bed combustion ash-based, supplemented with carbide slag and desulfurization gypsum, composed entirely of complete industrial wastes. The results show that CFBC ash has better pozzolanic activity than fly ash. When stabilizer total content is 10% and the ratio of CFBC ash : carbide slag : desulfurization gypsum is 7.2 : 1.8 : 1, compressive strength of stabilized soil can reach the maximum of 2.12 MPa at the age of 28 d of curing. Stabilizer can meet the strength requirements of cement-soil mixing pile composite foundation and cement-soil mixing pile waterproof curtain.

  5. Quantifying mold biomass on gypsum board: Comparison of ergosterol and beta-N-acetylhexosaminidase as mold biomass parameters

    Reeslev, M.; Miller, M.; Nielsen, Kristian Fog


    Two mold species, Stachybotrys chartarum and Aspergillus versicolor, were inoculated onto agar overlaid with cellophane, allowing determination of a direct measurement of biomass density by weighing. Biomass density, ergosterol content, and beta-N-acetylhexosaminidase ( activity were...... monitored from inoculation to stationary phase. Regression analysis showed a good linear correlation to biomass density for both ergosterol content and beta-N-acetylhexosaminidase activity. The same two mold species were inoculated onto wallpapered gypsum board, from which a direct biomass measurement...... density from ergosterol content and beta-N-acetylhexosaminidase activity were determined. The CFs were used to estimate the biomass density of the molds grown on gypsum board. The biomass densities estimated from ergosterol content and beta-N-acetylhexosaminidase activity data gave similar results...

  6. Precise timing of lacustrine gypsum in Luobubo, Xinjiang using the thermal ionization mass spectrometry U-series method


    Dating techniques including gypsum dissolu tion in water, iron hydroxide co-precipitation with uranium and thorium and mass spectrometric determination have been investigated in this note. The ages of the gypsum sam ples in a CK core from Luobubo lacustrine sediments are in the range of (12.85 ± 0.21) kaBP (4 m distance from the top core) to (153.2± 7.2) kaBP (49 m distance from the top core) with the relative errors of ± 1.6%-± 4.7%. It indicates that the sedimental environment of the CK core was situated in the middle-late Pleistocene and Holocene periods, corre sponding to 1--6 stages of oxygen isotopes in the abyssal sediments and included much information from last inter glacial to Holocene warm periods.

  7. Evaluation of surface detail reproduction, dimensional stability and gypsum compatibility of monophase polyvinyl-siloxane and polyether elastomeric impression materials under dry and moist conditions

    Vadapalli, Sriharsha Babu; Atluri, Kaleswararao; Putcha, Madhu Sudhan; Kondreddi, Sirisha; Kumar, N. Suman; Tadi, Durga Prasad


    Objectives: This in vitro study was designed to compare polyvinyl-siloxane (PVS) monophase and polyether (PE) monophase materials under dry and moist conditions for properties such as surface detail reproduction, dimensional stability, and gypsum compatibility. Materials and Methods: Surface detail reproduction was evaluated using two criteria. Dimensional stability was evaluated according to American Dental Association (ADA) specification no. 19. Gypsum compatibility was assessed by two crit...

  8. Isotopic composition of gypsum hydration water in deep Core SG-1, western Qaidam basin (NE Tibetan Plateau), implications for paleoclimatic evolution

    Li, Jiao; Li, Minghui; Fang, Xiaomin; Zhang, Gengxin; Zhang, Weilin; Liu, Xiaoming


    The oxygen and hydrogen isotopic compositions of gypsum hydration water can be useful for determining the isotopic composition of the original brine from which gypsum precipitated. However, relatively few long-term and continuous records of the stable isotope geochemistry of gypsum hydration water in arid regions have been reported. We measured the δ18O and δD of primary gypsum hydration water from a 938.5 m-long deep core (SG-1) in the western Qaidam Basin to study the mechanisms that contributed to gypsum formation and to reconstruct potential paleoclimatic change. The measured δ18O and δD ranged from - 4.21‰ to 8.69‰ and from - 72.77‰ to 49.73‰, respectively. The linear relationship between δ18O and δD indicates that meteoric water was the original source of the gypsum hydration water. The gradient of 5.39 for the δ18O and δD plots is lower than that of global meteoric water, suggesting that paleo-lakewater evaporated and became a CaSO4-rich brine leading to gypsum deposition. The evaporation/precipitation (E/P) ratio played an important role in determining δ18O and δD. The oscillations noted in the δ18O and δD of the gypsum hydration water imply that: (a) there was a long-term and stepwise aridification after 2.2 Ma in the western Qaidam Basin; and (b) there were three increasingly dry phases at 2.2-1.2 Ma, 1.2-0.6 Ma, and 0.6-0.1 Ma, with two cold and dry events at 1 Ma and 0.6 Ma. Global cooling, especially during the Mid Pleistocene Climate Transition event (MPT), may have been the primary cause of the aridification recorded in core SG-1 in the Asian inland.

  9. Shaking table model test and engineering practice of a new gypsum-adobe walls dwelling in Xinjiang autonomous region, China

    ZHOU Tie-gang; HU Xin; YU Chang-xia


    The paper introduces a new type of green building which suits for the construction of rural dwellings in Xinjiang, China. Results of the shaking table test on building model show that the single-layer gypsum-adobe structure has better seismic performance. And it also analyzes the construction features and engineering practice, which means that it is significant to extend this type of building to the drier regions in China.

  10. Estimates of inhalation doses resulting from the possible use of phospho-gypsum plaster-board in Australian homes.

    O'Brien, R S; Peggie, J R; Leith, I S


    Current materials used as internal lining in Australian buildings are based on natural gypsum of low radium content. A study was carried out to estimate the contribution to the annual effective dose due to airborne contamination from chemical by-product gypsum plaster-board of higher radium content if it were used as an internal lining. The 226Ra content and 222Rn exhalation rate were measured for several samples of the plaster-board, and the behavior of 222Rn and its progeny (218Po, 214Pb, 214Bi, and 214Po) in a typical building was modeled numerically, using the results of the exhalation rate measurements as input. For building ventilation rates greater than approximately 0.5 air changes per hour, the contribution to the total annual effective dose from inhalation of 222Rn and its progeny exhaled from the phospho-gypsum plaster-board is estimated to be below 1 mSv. This contribution is reduced if the surface of the plaster-board is coated with paint or cardboard, or if the very fine particles are removed from the phospho-gypsum during manufacture of the plaster-board. The effective doses arising from dust generation during the installation of the plaster-board are also estimated to be below 1 mSv. The recommended action level of 200 Bq m-3 for radon in air in Australia corresponds to an annual effective dose of approximately 6 mSv. The study indicates that the suggested acceptable level of 185 Bq kg-1 for the 226Ra concentration in the plaster-board may be too restrictive under Australian conditions.

  11. Hydrochemical features of groundwater in a coastal gypsum karst (Marina di Lesina, Gargano, Southern Italy) in relation to tides

    Fidelibus, Maria Dolores; Campana, Claudia


    As part of a complex monitoring aimed at collecting suitable data for conceptual and numerical modelling of the coastal gypsum karst of Marina di Lesina (Gargano, Southern Italy), 64 groundwater samples were collected during three surveys at different depths from 9 monitoring wells aligned along two transects. The transects, perpendicular to the Acquarotta canal, are less of 1 Km long. The canal is directly connected to the sea and to the Lesina Lagoon and behaves as an oscillating border following sea tides. The sampling campaigns were carried out concurrently to phases of increasing, decreasing, and low tide and provide different frameworks of the chemical composition of ground waters. TDS (Total Dissolved Solids) of ground water samples ranges from 0.2 g/l to 35 g/l and increases generally along the flow lines towards the canal, and downward. The concentrations of the major ions deviate from theoretical ones defined by non-reactive mixing lines, which have as saline end-member either standard seawater or local seawater sampled offshore.Owing to the multi-component character of the hydrochemical system, the cation concentrations are controlled by competition among concurrent water-rock interaction processes that overlap to non-reactive freshwater-saltwater (FW-SW) mixing, being even triggered and/or enhanced by the same mixing, with feedback loops: gypsum and calcite dissolution, ion exchange (with direction depending on hydrodynamic conditions mainly driven by tides, and justified due to the presence of clay in the gypsum bedrock), and dedolomitization. The geochemical study also highlights the involvement of saline ground waters belonging to regional circuits that develop in the huge Mesozoic carbonate basement. The study highlights that in the saturated thickness of the gypsum coastal aquifer closer to the coast, the hydrochemical system is extremely reactive and strongly influenced by the different groundwater hydraulic conditions induced by the tide phases.

  12. Synthesis of Fluorite (CaF2 Crystal from Gypsum Waste of Phosphoric Acid Factory in Silica Gel

    Mohammad Misbah Khunur


    Full Text Available This paper report the synthesis and characterization of fluorite single crystal prepared from gypsum waste of phosphoric acid production in silica gel. Instead of its high calcium, gypsum was used to recycle the waste which was massively produces in the phosphoric acid production. The gypsum waste, the raw material of CaCl2 supernatant, was dissolved in concentrated HCl and then precipitated as calcium oxalate (CaC2O4 by addition of ammonium oxalate. The CaCl2 was obtained by dissolving the CaC2O4 with HCl 3M. The crystals were grown at room temperature in silica gel and characterized by AAS, FTIR and powder XRD. The optimum crystal growth condition, which is pH of gel, CaCl2 concentration and growth time, were investigated. The result shows that at optimum condition of pH 5.80, CaCl2 concentrations of 1.2 M, and growth time of 144 hours, colorless crystals with the longest size of 3 mm, were obtained (72.57%. Characterization of the synthesized crystal by AAS indicates that the obtained crystal has high purity. Meanwhile, analysis by FTIR spectra shows a Ca–F peak at 775 cm-1, and powder-XRD analysis confirms that the obtained crystal was fluorite (CaF2. © 2012 BCREC UNDIP. All rights reservedReceived: 11st April 2012; Revised: 4th June 2012; Accepted: 13rd June 2012[How to Cite: M.M. Khunur, A. Risdianto, S. Mutrofin, Y.P. Prananto. (2012. Synthesis of Fluorite (CaF2 Crystal from Gypsum Waste of Phosphoric Acid Factory in Silica Gel. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (1: 71-77.  doi:10.9767/bcrec.7.1.3171.71-77 ][How to Link / DOI: ] | View in 

  13. Microbial diversity in the deep-subsurface hydrothermal aquifer feeding the giant gypsum crystal-bearing Naica Mine, Mexico

    Marie eRagon; Alexander ES Van Driessche; Juan Manuel eGarcia Ruiz; David eMoreira; Purificacion eLopez-Garcia


    The Naica mine in Northern Mexico is famous for its giant gypsum crystals, which may reach up to 11 m long and contain fluid inclusions that might have captured microorganisms during their formation. These crystals formed under particularly stable geochemical conditions in cavities filled by low salinity hydrothermal water at 54-58°C. We have explored the microbial diversity associated to these deep, saline hydrothermal waters collected in the deepest (ca. 700-760 m) mineshafts by amplif...

  14. Geotechnical properties of peat soil stabilised with shredded waste tyre chips in combination with gypsum, lime or cement

    M. Saberian


    Full Text Available Peat has a high content of water and organic substances. These weak components can cause low bearing capacity and high consolidation settlement under load, which means that peat deposits must usually be stabilised if they are to bear constructions such as buildings or roads. In this study we investigated the performance of waste tyre chips (10 % by weight and sand (400 kg m-3 supplemented with a pozzolanic binder (gypsum, lime or cement at a range of dosages (5 %, 10 % or 15 % by weight as a stabiliser for peat soil. Peat samples were taken from a fen peatland at Chaghakhor Wetland in Chahar Mahal and Bakhtiari Province, Iran. In total, 162 test specimens were prepared and subjected to laboratory strength testing (unconfined compression test and direct shear test. Additionally, the pH of each admixture was recorded immediately after mixing, elemental compositions were determined by X-Ray Fluorescence (XRF, and structures were examined using Scanning Electron Microscopy (SEM. It was observed that: (1 the total percentage of pozzolanic compounds in the peat soil was well below the minimum of 70 % set by the standard ASTM C 618 (ASTM 2000, so an additive such as cement, lime or gypsum would certainly be required; (2 specimens stabilised with gypsum or lime showed improvements in unconfined compressive strength (UCS, but those stabilised with ordinary Portland cement exhibited the greatest improvement in UCS (up to 12,200 % as well as improvements in the direct shear parameters c and φ; (3 according to the XRF tests, additives such as cement, lime and gypsum introduced considerable amounts of Si, Al, Ca and O, which are important for pozzolanic reactions in peat soils; and (4 on the basis of the results of UCS and direct shear tests, the optimum percentage of the additives tested would be 5 %.

  15. Flue gas desulfurization gypsum: implication for runoff and nutrient losses associated with broiler litter use on pastures on ultisols.

    Endale, Dinku M; Schomberg, Harry H; Fisher, Dwight S; Franklin, Dorcas H; Jenkins, Michael B


    Gypsum has been shown to reduce runoff on soils prone to crust formation in the southeastern United States. Increased infiltration from gypsum applications could therefore help reduce runoff P and other nutrient losses from application of broiler litter (BL), a nutrient-rich fertilizer. In rainfall simulation experiments in June 2009 and May 2011, runoff and nutrient (N, P, Ca, Mg) losses in runoff were compared among treatments consisting of 0, 2.2, 4.5, and 9.0 Mg ha flue gas desulfurization gypsum (FGDG) combined with 13.5 Mg ha of BL and two control treatments of (0-0) and (9.0-0.0) Mg ha (FGDG-BL). A randomized block design with three replications was set up on a Cecil (Typic Kanhapludult) soil growing Coastal bermudagrass ( L.) for hay near Watkinsville, Georgia. Amendments were applied each April from 2009 to 2011. A reduction in runoff of 30% each year from the (9.0-13.5) compared with the (0-0) treatment was not statistically significant. Gypsum was effective in reducing concentration and load in one of the two study years: P and NH-N in 2009 (up to 83%) and NO-N in 2011 (up to 73%). A combination of factors related to weather extremes, timing of FGDG and BL applications, and their implication on soil and vegetation responses at different landscape positions might have caused the different responses between years. Additional studies focused on isolating the impacts of such factors would be helpful to ascertain the effectiveness of multiyear applications of FGDG as a best management practice to reduce P and other nutrient losses in soils of the southeastern United States. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  16. Possible utilization of flue-gas desulfurization gypsum and fly ash for citrus production: Evaluation of crop growth response

    Alva, A.K. (Univ. of Florida, Lake Alfred, FL (United States). Citrus Research and Education Center)


    The application of industrial by-products to agricultural land has been a topic of considerable interest during recent years. For the industries, this is an attractive avenue to utilize the by-products rather than land filling. Agriculturists/horticulturists are faced with a new challenge to evaluate the potential advantages of this practice in terms of crop growth, production, and quality as well as effects of such practices on environmental quality. Fly ash and flue-gas desulfurization (FGD) gypsum are by-products produced from coal-fired electric power generation plants. There is a growing interest in evaluation of potential benefits of land application of coal combustion by products mixed with organic by-products. The objective of this study was to investigate the effects of application of FGD gypsum, fly ash or chicken manure,, or application of the former two in combination with the latter, on soil properties as well as on growth and mineral nutrition of Cleopatra mandarin and Swingle citrumelo rootstock seedlings grown on a Myakka sand. The growth of seedlings of either rootstock improved significantly in soils amended with either FGD gypsum, fly ash, or chicken manure, individually or in combination of either by-product with chicken manure. However, the ranking of various amendments in relation to growth response differed between the two rootstocks. The combined application of all three amendments decreased the growth of both rootstock seedlings significantly as compared to that of seedlings in unamended soil. The application of either FGD gypsum, fly ash, or chicken manure each at 2 g/kg soil increased the concentration of Ca, Ca and K, and Ca and P in the leaves of seedlings, respectively.

  17. Potential of soil amendments (Biochar and Gypsum) in increasing water use efficiency of Abelmoschus esculentus L. Moench.

    Batool, Aniqa; Taj, Samia; Rashid, Audil; Khalid, Azeem; Qadeer, Samia; Saleem, Aansa R; Ghufran, Muhammad A


    Water being an essential component for plant growth and development, its scarcity poses serious threat to crops around the world. Climate changes and global warming are increasing the temperature of earth hence becoming an ultimate cause of water scarcity. It is need of the day to use potential soil amendments that could increase the plants' resistance under such situations. Biochar and gypsum were used in the present study to improve the water use efficiency (WUE) and growth of Abelmoschus esculentus L. Moench (Lady's Finger). A 6 weeks experiment was conducted under greenhouse conditions. Stress treatments were applied after 30 days of sowing. Plant height, leaf area, photosynthesis, transpiration rate (Tr), stomatal conductance and WUE were determined weekly under stressed [60% field capacity (F.C.)] and non-stressed (100% F.C.) conditions. Stomatal conductance and Tr decreased and reached near to zero in stressed plants. Stressed plants also showed resistance to water stress upto 5 weeks and gradually perished at sixth week. On the other hand, WUE improved in stressed plants containing biochar and gypsum as compared to untreated plants. Biochar alone is a better strategy to promote plant growth and WUE specifically of A. esculentus, compared to its application in combination with gypsum.

  18. Potential of Soil Amendments (Biochar and Gypsum in increasing Water Use Efficiency of Abelmoschus esculentus L. Moench

    Aniqa eBatool


    Full Text Available Water being an essential component for plant growth and development, its scarcity poses serious threat to crops around the world. Climate changes and global warming are increasing the temperature of earth hence becoming an ultimate cause of water scarcity. It is need of the day to use potential soil amendments that could increase the plants’ resistance under such situations. Biochar and gypsum were used in the present study to improve the water use efficiency and growth of Abelmoschus esculentus L. Moench (Lady’s Finger. A six weeks experiment was conducted under greenhouse conditions. Stress treatments were applied after thirty days of sowing. Plant height, leaf area, photosynthesis, transpiration rate, stomatal conductance and water use efficiency were determined weekly under stressed (60% field capacity and non-stressed (100% field capacity conditions. Stomatal conductance and transpiration rate decreased and reached near to zero in stressed plants. Stressed plants also showed resistance to water stress upto five weeks and gradually perished at sixth week. On the other hand, water use efficiency improved in stressed plants containing biochar and gypsum as compared to untreated plants. Biochar alone is a better strategy to promote plant growth and WUE specifically of Abelmoschus esculentus, compared to its application in combination with gypsum.

  19. Contribution study to the thermal insulation of the builders in the desert regions of exploiting gypsum fiber reinforced palm

    Hafsi, Fouad; Kriker, Abdelouahed; Abani, Said


    Algerian Desert areas were characterized by very hot climate in summer and very cold in winter. The most widely used building material in these areas are concrete, mortar cement, which has a bad thermal insulation, causing a significant increase in cooling and heating costs; in order to avoid this problem it become a must to replace these materials with a good thermal isolation material and lower production cost. This work is part of the evaluation of local materials by improving their performance in the field of thermal insulation, which is considered a first step in the development of new local materials to be used in the construction field, the material used in this study is the gypsum reinforced with date palm fiber. In fact, Algeria has extraordinary resources in natural fibers (from Palm, Abaca, Hemp…) but without any large valorization in building materials. The aim of this work is then to characterization of those date palm fibers in new building materials approved for use in the construction of buildings in the desert areas. The date palm fibers were added to samples of the gypsum material in the form of cutting layers at different volume fraction, so as to determine the extent of their impact in the improvement of the thermal performance. The results were very satisfactory, reaching improvement rate of 16% for samples gypsum reinforced with single cut fiber form, and 32% of the samples reinforced with fiber in the form of layers.

  20. Simulation and Prediction of Ion Transport in the Reclamation of Sodic Soils with Gypsum Based on the Support Vector Machine

    Jinman Wang


    Full Text Available The effect of gypsum on the physical and chemical characteristics of sodic soils is nonlinear and controlled by multiple factors. The support vector machine (SVM is able to solve practical problems such as small samples, nonlinearity, high dimensions, and local minima points. This paper reports the use of the SVM regression method to predict changes in the chemical properties of sodic soils under different gypsum application rates in a soil column experiment and to evaluate the effect of gypsum reclamation on sodic soils. The research results show that (1 the SVM soil solute transport model using the Matlab toolbox represents the change in Ca2+ and Na+ in the soil solution and leachate well, with a high prediction accuracy. (2 Using the SVM model to predict the spatial and temporal variations in the soil solute content is feasible and does not require a specific mathematical model. The SVM model can take full advantage of the distribution characteristics of the training sample. (3 The workload of the soil solute transport prediction model based on the SVM is greatly reduced by not having to determine the hydrodynamic dispersion coefficient and retardation coefficient, and the model is thus highly practical.

  1. Uptake of Nutrients in Vegetables Grown on FGD-Gypsum-Amended Soils

    Yutdanai Yodthongdee


    Full Text Available This research evaluated the effects of using flue gas desulphurization gypsum (FGDG for growing of some agronomic crops. The FGDG was added to soil at 0, 2.5, 5.0 and 7.5% by weight. The test plants, Chinese kale and green bean, were grown and harvested after 45 days and 60 days, respectively. Application of FGDG at all ratios significantly increased pH of the soil, due to the lime containing in FGDG. The heavy metals content in plants grown in the FGDG treated tanks were not significantly different from those of the control tank. From the ten studied elements in Chinese kale and green bean seed tissues (As, Ca, Cd, Cr, Cu, K, Mg, Na, Pb, and Zn, the content of five toxic elements (As, Cd, Cr, Cu, and Pb were very low and not significantly influenced by FGDG, while the content of some nutrient elements (K, Ca, Mg in the plant tissues growing in FGDG treated soil were higher than the control. Concentration of some micronutrients (Cu and Zn in plants decreased with increasing dose of FGDG. There has not been any negative effect from applying up to 5.0% FGDG in soil. The results showed possibility of using FGDG as soil amendment in terms of agricultural production and safety.


    S. Z. M. NOR


    Full Text Available In this study, several formulations of gypsum bonded investment (GBI as a mould for copper alloy casting has been developed and their properties had been investigated. The mould was developed using Terengganu local silica sand with the average particle size of 220–250 µm, acted as a refractory and Plaster of Paris (POP as a binder. The formulations used were 75% local silica, 25% plaster and various amounts (31–37% of water. The compressive strength, tensile strength, porosity, core hardness and mould hardness properties of the prepared GBI were studied. It has been found that both compressive strength and tensile strength reduced with a water content due to an increment of mould porosity which was confirmed via Scanning Electron Microscopy analysis. The mould hardness was found unchanged, but the core hardness was slightly reduced with the increment of water. The compressive strength of GBI moulds developed in this work was in the range of 600–1100 kN/m2, which was sufficient for copper alloy casting.

  3. Problems and possible remedies concerning NORM in by-Product gypsum produced by the phosphate industry

    Burnett, W.C.; Hull, C.D [Florida State Univ., Tallahassee, FL (United States). Dept. of Oceanography


    Large quantities ({approx} 30 million tons/year) of phosphogypsum are produced as a by-product of fertilizer production in Florida. The sedimentary phosphate rock, used as the raw material for phosphoric acid production, is enriched in uranium and daughter products. Relatively high concentrations of some of these U-series daughters, particularly {sup 226} Ra (av. = 910 Bq.Kg{sup -1}), prevent use of the by-product gypsum for construction or other purposes. The material is thus stockpiled on huge stacks which are unsightly and a potential threat to the surrounding air and especially groundwater resources. It is estimated that {approx} 10{sup 9} tons of this material will be on Florida stacks by the turn of the century. We have been investigating the detailed radiochemistry of phosphogypsum in the hope that can understanding of how these radionuclides are fixed in the material may lead to cost-effective purification schemes. Our work has focused on the distribution of {sup 226} Ra but has also included {sup 210} Pb and {sup 210} Po (av. = 860 Bq.Kg{sup -1}) which are also enriched in phosphogypsum. This paper summarizes the problems associated with this material and reviews its radiochemistry as elucidated by sequential extraction and other methodologies. We also present some possible alternatives to long-term storage as a solution to the phosphogypsum problem. (author) 4 figs., 1 tab.

  4. Combination of simvastatin, calcium silicate/gypsum, and gelatin and bone regeneration in rabbit calvarial defects

    Zhang, Jing; Wang, Huiming; Shi, Jue; Wang, Ying; Lai, Kaichen; Yang, Xianyan; Chen, Xiaoyi; Yang, Guoli


    The present study was performed to determine whether simvastatin improves bone regeneration when combined with calcium silicate/gypsum and gelatin (CS-GEL). The surface morphology was determined using field-emission scanning electron microscopy (FSEM). Degradation in vitro was evaluated by monitoring the weight change of the composites soaked in phosphate buffered saline (PBS). Drug release was evaluated using high-performance liquid chromatography (HPLC). Cytotoxicity testing was performed to assess the biocompatibility of composites. Four 5 mm-diameter bone defects were created in rabbit calvaria. Three sites were filled with CS-GEL, 0.5 mg simvastatin-loaded CS-GEL (SIM-0.5) and 1.0 mg simvastatin-loaded CS-GEL (SIM-1.0), respectively, and the fourth was left empty as the control group. Micro-computed tomography (micro-CT) and histological analysis were carried out at 4 and 12 weeks postoperatively. The composites all exhibited three-dimensional structures and showed the residue with nearly 80% after 4 weeks of immersion. Drug release was explosive on the first day and then the release rate remained stable. The composites did not induce any cytotoxicity. The results in vivo demonstrated that the new bone formation and the expressions of BMP-2, OC and type I collagen were improved in the simvastatin-loaded CS-GEL group. It was concluded that the simvastatin-loaded CS-GEL may improve bone regeneration.

  5. New design options with gypsum-based cooling ceilings; Neue Gestaltungsmoeglichkeiten mit Gipskuehldecken

    Bringmann, A.


    The Sulzer administrative building at Winterthur, Switzerland, was constructed in 1928/'29 by the architect Lebrecht Voelkli. It was now modernized by the Zuerich architects, Marianne Burkhalter and Christian Sumi. The technical facilities, with a traditional heating system and modern air conditioning, was planned and constructed by Axima. As new elements, there are gypsum-based cooling ceilings which have the advantages of easy integration in the building design, high economic efficiency, and user-friendliness. The emphasis during modernisation was on architectural aspects, i.e. modern interior design, colour schemes, acoustics and flexible use of rooms. [German] 1928/29 erstellte der Architekt Lebrecht Voelkli einen Neubau fuer die Sulzer-Konzernleitung in Winterthur (Schweiz) in Gestalt eines neoklassischen Wuerfels mit vier oberirdischen Geschossen. Dessen komplette Sanierung realisierten die Zuercher Architekten Marianne Burkhalter und Christian Sumi. Die von Axima geplante und ausgefuehrte Gebaeudetechnik mit traditioneller Heizung und modernen Luftaufbereitungsanlagen weist als Novum neu konzipierte Gipskuehldecken auf. Sie erfuellen die Architektenansprueche in Bezug auf unauffaellige Integration, Wirtschaftlichkeit und Benutzerfreundlichkeit, denn im Vordergrund standen Forderungen nach moderner Innenraumgestaltung, akzentuierter Farbgebung, guter Akustik und flexibler Flaechennutzung. (orig.)

  6. 湿法脱硫系统“石膏雨”问题的成因及解决对策%Origin and solution of the“gypsum rain”problem of limestone-gypsum WFGD system

    翁卫国; 张军; 李存杰


    “石膏雨”现象已逐渐引起社会各界的关注,研究合理、有效的解决方法已成为当前燃煤烟气污染物控制的重要课题之一。本文对影响“石膏雨”形成的因素进行了分析,湿法脱硫系统取消烟气换热器致使排烟温度降低是“石膏雨”产生的主要原因,其主要影响因素包括设备设计及运行、操作参数变化及外界环境。综述了“石膏雨”检测方法:“石膏雨”的主要成分(浆滴、细颗粒物及 SO3酸雾)的检测手段主要分为采样后化学分析法及电荷或光学物理化学法。针对“石膏雨”的现象提出除尘设备及脱硫系统的设计运行优化、尾部烟道设计优化及增设湿式静电除尘器三种主要的解决措施。面对日益严峻的“石膏雨”问题,政府应当尽快颁布相关规章制度,同时积极开展“石膏雨”的监督检查工作。%The problem of“gypsum rain”has gradually aroused the concern of the society,and the study of reasonable and effective solution has become one of the most important topics in the research of coal-fired flue gas pollution control. In this paper,the factors affecting the formation of“gypsum rain” were analyzed. The main reason for “gypsum rain” was canceling gas gas heater (GGH) in the wet flue gas desulfurization (WFGD) system which lowered exhaust temperature,and other influence factors included equipment design,operation parameters and external environment. The measurement methods of “gypsum rain” were reviewed. Measurement of the main composition of “gypsum rain”(slurry drops,fine particulate matter and SO3 acid mist) could be classified into chemical analysis after sampling,and electric charge or optical physical chemistry method. Three solutions of design and operation optimization of dust removal equipment and FGD system,design optimization of tail flue gas duct,and additional wet electrostatic precipitator (WESP) were proposed

  7. Indoor Pollution Emissions from Building Materials; Case of Study: Gypsum Boards Indoor Pollution Emissions from Building Materials; Case of Study: Gypsum Boards

    Silverio Hernández Moreno


    Full Text Available Este reporte presenta una evaluación de las emisiones de materiales de construcción, al interior de los edificios que pueden causar daño a la salud de los usuarios durante la ocupación, pues emiten sustancias tóxicas al interior de los edificios. Este reporte presenta un caso de studio que evalúa a los tableros de yeso, frecuentemente usados en la construcción de muros divisorios y falsos plafones. La parte experimental se basa en un espacio tridimensional el cual simula un cuarto de cualquier tipo de edificación; por ejemplo: un salón de clases u oficina. Las condiciones ambientales al interior, tales como: ventilación, temperatura y humedad, afectan directamente las emisiones de sustancias químicas por los materiales de construcción. La metodología se basa en la comparación de materiales convencionales y materiales alternativos con distinta composición y similares características, en donde usamos métodos de prueba, condiciones ambientales, instrumentos y herramientas similares. Este es un estudio muy importante para entender los problemas relacionadoscon la contaminación ambiental, específicamente del aire y sus efectos en el interior de los edificios, y que se relaciona directamente con la salud pública e indirectamente con los sistemas constructivos y la selección de materiales en los edificios. Las pruebas concluyen que los materiales alternativos (de contenido reciclado son mejores que los tradicionales, porque reducen la contaminación del aire al interior de los edificios. This report presents an evaluation of emissions from indoor building materials that may cause health damage to the people who occupy the building, since these materials emit toxic chemicals into the air and indoor surfaces. This report presents a case study which evaluates Gypsum Boards, frequently used in the construction of dividing walls and ceilings. The experimental part of this report is based on a three-dimensional space that simulates a

  8. Comparison of the Surface Roughness of Gypsum (Dental Stone with three Types of Tissue Conditioner Impression Materials over Time

    Nili M.


    Full Text Available Statement of Problems: Although the primary use of tissue conditioners is for healing the damaged mucosa but they can also be used as functional impression; it seems that its effeicasy depends on its viscoelastic features such as compatibility with gypsum and surface roughness.Purpose: The aim of this study is to compare the surface roughness of gypsum with several tissue conditioner impression materials avaliable in the market.Materials and Method: In this experimental study, three tissue conditioners (Acrosoft, viscogel & GC were used. Pars dental gypsum moldano Type III and a polyvinyl siloxane impression were used for the controls. The tissue conditioners powder liquid ratio was mixed according to the manufacturer’s recommendation and immediately poured in a mold with an internal diameter of 18 mm and depth of 2mm. The mold was completely filled. Then, a glass block with the mean roughness of 0.8 µm was placed on its surface for two hours. Then, the 5 samples were immediately placed in 37oC water for 0-24 hrs, 3, 7, and 14 days. After that, the specimens were beaded, boxed and poured with pars dental gypsum type III. The gypsum sample’s surface roughness was measured with profilometer with the length of 2.5 mm and cut-off of 0.8 mm. The results were analyzed using ANOVA and Tukey tests.Results: The results showed that surface roughness of Acrosoft in different storage times did not change significantly and there was no significant difference between Acrosoft and the control group. Viscogels surface roughness was significantly different with all other groups at zero time; with the increase of storage time the surface roughness decreases. The control group showed a significant difference with viscogel at zero time and with GC at 24 hrs and 3 days but it revealed no difference with the other groups. The least surface roughness belonged to GC at zero and 14 days and the highests surface roughness belonged to viscogel at zero time

  9. Experimental study of phosphorous gypsum based insulation mortar powder material%磷石膏基保温砂浆胶粉料试验研究

    王玉麟; 赖振斌; 黄巧玲; 漆贵海


    The article studies on preparation of thermal insulation mortar powder materials with phosphorus gypsum which was an industrial waste residue, supplemented with cement and slag powder. Phosphorous gypsum based thermal insulation mortar powder material is prepared by experimental study and analysis on the influence of various factors to the mechanical properties and softening coefficient of phosphorous gypsum based mineral binder. The optimized formulation is verified. Through the comparison of mechanical properties and water absorption of gypsum based reference specimen, it is obtained that in the prepared phosphorus gypsum-based insulation mortar, the phosphorus gypsum amount is 54%, slag content is 30%, lime is 5%, cement is 10% and admixture is 1%, which provides a new approach for comprehensive utilization of phosphorus gypsum.%利用工业废渣磷石膏作为主要胶凝材料,辅以水泥、矿渣粉等研制保温砂浆胶粉料.通过各因素对磷石膏基胶粉料力学性能与软化系数影响的试验研究及分析,配制出了磷石膏基保温砂浆胶粉料.并对优化后的配方进行了验证;石膏基准试件的力学性能与吸水率进行了比较,得出磷石膏基保温砂浆中的磷石膏用量为54%时,矿渣掺量为30%,石灰为5%,水泥为10%,外加剂为1%,以期为磷石膏的有效利用提供新的途径.

  10. Karst-on-a-chip: microfluidic studies of dissolution of a gypsum fracture

    Szymczak, Piotr; Dutka, Filip; Osselin, Florian


    Dissolution of fractured and porous media introduces a positive feedback between fluid transport and chemical reactions at mineral surfaces leading to self-focusing of the flow in pronounced wormhole-like channels [1,2]. We study the flow-induced dissolution in a simple microfluidic setup, with a gypsum block inserted in between two polycarbonate plates, which is the simplest model of a fracture [3]. This gives us a unique opportunity to observe the evolution of the dissolution patterns in-situ and in real-time. By changing the flow rate and the aperture of the fracture we can scan a relatively wide range of Peclet and Damkohler numbers, characterizing the relative magnitude of advection, diffusion and reaction in the system. Additionally, as the aperture is increased, a transition is observed between the fractal and regular dissolution patterns. For small gaps, the patterns are ramified fractals. For larger gaps, the dissolution fingers are found to have regular forms of two different kinds: either linear (for high flow rates) or parabolic (for lower flow rates). The experiments are supplemented with numerical simulations and analytical modeling which allow for a better understanding of evolving flow patterns. In particular, we find the shapes and propagation velocities of dominant fingers for different widths of the system, flow rates and reaction rates. Finally, we comment on the link between the experimentally observed patterns and the natural karst systems - both cave conduits and epikarst solution pipes. [1] Hoefner, M. L. and Fogler, H. S. Pore evolution and channel formation during flow and reaction in porous media. AIChE J. 34, 45-54, 1988 [2] P. Szymczak, A. J. C. Ladd, Wormhole formation in dissolving fractures, J. Geophys. Res., 114, B06203, 2009 [3] F. Osselin, P. Kondratiuk, A Budek, O. Cybulski, P. Garstecki, P. Szymczak Microfluidic observation of the onset of reactive infiltration instability in an analog fracture, Geophys. Res. Lett., 43, 6907

  11. Bacterial communities and the nitrogen cycle in the gypsum soils of Cuatro Ciénegas Basin, coahuila: a Mars analogue.

    López-Lozano, Nguyen E; Eguiarte, Luis E; Bonilla-Rosso, Germán; García-Oliva, Felipe; Martínez-Piedragil, Celeste; Rooks, Christine; Souza, Valeria


    The OMEGA/Mars Express hyperspectral imager identified gypsum at several sites on Mars in 2005. These minerals constitute a direct record of past aqueous activity and are important with regard to the search of extraterrestrial life. Gale Crater was chosen as Mars Science Laboratory Curiosity's landing site because it is rich in gypsum, as are some desert soils of the Cuatro Ciénegas Basin (CCB) (Chihuahuan Desert, Mexico). The gypsum of the CCB, which is overlain by minimal carbonate deposits, was the product of magmatic activity that occurred under the Tethys Sea. To examine this Mars analogue, we retrieved gypsum-rich soil samples from two contrasting sites with different humidity in the CCB. To characterize the site, we obtained nutrient data and analyzed the genes related to the N cycle (nifH, nirS, and nirK) and the bacterial community composition by using 16S rRNA clone libraries. As expected, the soil content for almost all measured forms of carbon, nitrogen, and phosphorus were higher at the more humid site than at the drier site. What was unexpected is the presence of a rich and divergent community at both sites, with higher taxonomic diversity at the humid site and almost no taxonomic overlap. Our results suggest that the gypsum-rich soils of the CCB host a unique microbial ecosystem that includes novel microbial assemblies.

  12. CO2-C emissions associated to soil tillage, liming and gypsum applications in sugarcane areas under green and burned harvest

    Figueiredo, E. B.; Panosso, A. R.; La Scala, N., Jr.


    Debate regarding the potential of bioenergy crops to substitute fossil fuel in an efficient way is still opened. New management strategies from agricultural crops should be identified to increase their potential contributing to avoid the climate changes. This study quantified the impact of sugarcane harvest systems and other management practices on CO2-C fluxes following crop replanting. Two agricultural systems were considered: burned and green harvest, in plots where residues were left or removed from soil surface, from no till and after conventional tillage, with or without dolomite and agricultural gypsum applications. Soil CO2 emission, moisture and soil temperature were taken since 24 hours after tillage, totalizing 25 days after tillage with 18 measuring days. NT plots emissions were kept lower than others during the whole period studied, presenting in some cases fluctuations which were mostly related to changes in soil moisture associated to the occurrence of rain precipitations. Changes in CO2-C emission, in each of the harvest systems can be clearly seen when tillage, dolomite or gypsum were applied. The removal of sugarcane residues from soil surface resulted in almost immediate reduction of soil moisture (6% in volume) following an increase in soil NT CO2 emission of + 64%. The additional soil carbon emission due to the simple operation of removing the crop residues from soil surface was 252.4 kg CO2-C ha-1, as higher as the soil CO2 losses induced by tillage operation. Dolomite and agricultural gypsum applications did not always result in higher emissions, especially when applied at the presence of crop residues on soil surface. Reducing tillage frequency in green harvested sugarcane areas could reduce CO2 emissions and probably increasing the soil carbon stock considering long-term period crop system, while maintaining the sugarcane crop residues on soil surface has shown to be also a GHG mitigation option.

  13. Estimating mineral abundances of clay and gypsum mixtures using radiative transfer models applied to visible-near infrared reflectance spectra

    Robertson, K. M.; Milliken, R. E.; Li, S.


    Quantitative mineral abundances of lab derived clay-gypsum mixtures were estimated using a revised Hapke VIS-NIR and Shkuratov radiative transfer model. Montmorillonite-gypsum mixtures were used to test the effectiveness of the model in distinguishing between subtle differences in minor absorption features that are diagnostic of mineralogy in the presence of strong H2O absorptions that are not always diagnostic of distinct phases or mineral abundance. The optical constants (k-values) for both endmembers were determined from bi-directional reflectance spectra measured in RELAB as well as on an ASD FieldSpec3 in a controlled laboratory setting. Multiple size fractions were measured in order to derive a single k-value from optimization of the optical path length in the radiative transfer models. It is shown that with careful experimental conditions, optical constants can be accurately determined from powdered samples using a field spectrometer, consistent with previous studies. Variability in the montmorillonite hydration level increased the uncertainties in the derived k-values, but estimated modal abundances for the mixtures were still within 5% of the measured values. Results suggest that the Hapke model works well in distinguishing between hydrated phases that have overlapping H2O absorptions and it is able to detect gypsum and montmorillonite in these simple mixtures where they are present at levels of ∼10%. Care must be taken however to derive k-values from a sample with appropriate H2O content relative to the modeled spectra. These initial results are promising for the potential quantitative analysis of orbital remote sensing data of hydrated minerals, including more complex clay and sulfate assemblages such as mudstones examined by the Curiosity rover in Gale crater.

  14. Growth of cowpea plants inoculated with Rhizobium in a saline-sodic soil after application of gypsum

    Angela Jessyka Pereira Brito Fontenele

    Full Text Available Two experiments were carried out with the aim of evaluating the growth of cowpea cultivated in saline-sodic soils corrected with gypsum: one experiment in the laboratory, to identify the best level of gypsum for the correction of the saline-sodic soils of the state of Pernambuco, Brazil; and the other in a greenhouse, after correction of the soils. As the test plant, the cowpea cultivar pele de moça, inoculated with Rhizobium strain BR3267 was used. The experiments were arranged in a randomised block design in a 2 x 5 factorial arrangement, two soils and five levels of the gypsum requirement (GR, equivalent to 50, 100, 150, 200 and 250% of the GR of the soil, as determined by the Schoonover M-1 method, with five replications. The following were evaluated: electrical conductivity of the soil saturation extract (EC, soil exchangeable sodium and percentage of soil exchangeable sodium (ESP, number of nodules (NN, nodule dry weight (NDW, shoot dry weight (SDW, shoot height (PH and nitrogen concentration (N in the shoots. Application of 100% of the GR, followed by the enough water for leaching, was effective for the correction of soil sodicity. The application of increasing levels of soil GR resulted in an increase in the number of nodules, dry weight of the nodules and shoots, and the height and levels of N absorbed by the plants in soil S2. In soil S1, the use of levels of 200 and 250% of soil the GR caused a decrease in all the variables under study.

  15. Geochemistry and microbial diversity of cave waters in the gypsum karst aquifers of Emilia Romagna region, Italy.

    D'Angeli, Ilenia M; Serrazanetti, Diana I; Montanari, Chiara; Vannini, Lucia; Gardini, Fausto; De Waele, Jo


    Fifty-seven control points of waters (sinking streams, rivers in caves, and resurgences) hosted in gypsum karst areas in Emilia Romagna region (N-Italy) were sampled in the framework of a Project LIFE+08NAT/IT/000369 "Gypsum" in the period 2010-2014. The microbiology and chemistry of these waters have been analyzed to evaluate the impact of human activities or natural factors, in the gypsum karst systems. Waters have been analyzed for major chemistry (Ca, Mg, Na, K, SO4, HCO3, Cl, NO3) and some minor constituents (F, Br, NH4 and PO4), measuring pH, electric conductivity (EC), total dissolved solids (TDS) and temperature (T) in situ. The same samples have been analyzed with traditional microbiology techniques focused on total microbial count and on fecal microbiota, as index of human and/or animal contamination, and molecular biology techniques (sequencing of 16S rRNA segment and PCR-DGGE), focused on the characterization of microbial populations in the different sampling sites and determination of their variations and/or changes during the five years of the project. As expected, waters tend to be increasingly mineralized from sinking streams to resurgences, with only local and temporarily high contents in nitrates and ammonium, often related to the presence of bat colonies. PCR-DGGE revealed ecological changes, in terms of microbial populations present in the bulk water samples, in different sampling sites within the same cave. Although the impact of fecal microorganisms only rarely exceeded 2 log UFC/ml, the results evidenced fluctuations of these microorganisms mainly correlated to the season and to the biological activity of bats. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Use of the “red gypsum” industrial waste as substitute of natural gypsum for commercial cements manufacturing

    Gázquez, M. J.


    Full Text Available The main objective of this research has been the valorisation of a waste from the TiO2 production process (sulphate method, called red gypsum, in the production of cements. This waste is mainly formed by di-hydrate calcium sulphate and iron hydroxides. To cover this objective it has been necessary to perform the physico-chemical characterisation of the red gypsum as well as the main components in the production of cements and of the new cements generated. Moreover, for the red gypsum, has been analyzed its radioactive content because it is generated in a NORM (Naturally Occurring Radioactive Materials industry. Finally, the most important properties of the obtained cements with different proportions of red gypsum in their composition have been studied by comparing them with the standard ones obtained in a Portland cement. Lastly, we have demonstrated that the new cements fulfil all the quality tests imposed by the European legislation.

    El objetivo de esta investigación ha sido analizar la valorización de un residuo generado en el proceso de producción de dióxido de titanio (vía sulfato, denominado yeso rojo, en la producción de cementos. Dicho residuo está compuesto fundamentalmente por sulfato de calcio di-hidratado e hidróxidos de hierro. Para ello, ha sido necesaria la caracterización físico-química del yeso rojo, así como la de los otros componentes fundamentales en la fabricación de cementos y de los cementos generados con el mencionado residuo. Además, en el caso del yeso rojo, se ha analizado su contenido radiactivo al generarse éste en una industria NORM (Natural Occurring Radioactive Materials. Posteriormente, se han estudiado las propiedades más importantes de los cementos producidos con diferentes porcentajes de yeso rojo añadido, comparando estas mezclas con las propiedades de un cemento Portland comercial, comprobándose que se cumplen todas las normas Europeas de calidad exigibles.

  17. Authigenic Gypsum in Gas-Hydrate Associated Sediments from the East Coast of India (Bay of Bengal)

    Kocherla, M.

    sequence recovered at station MD- 161-18 was divided into two lithologic units (Unit I (0-12 m) and Unit II (12-32 m) based on the authigenic mineral assemblages. Interestingly Unit I lacks authigenic minerals except small carbonate patches sporadically... minerals and have typical peaks of gypsum. The upper sedimentary sequence up to 12 mbsf lacks authigenic carbonates except small patches sporadically distributed from 7.5 to 8.5 mbsf and as fine grained carbonate bands (~5cm thick) at 22 mbsf...

  18. Relative Shock Effects in Mixed Powders of Calcite, Gypsum, and Quartz: A Calibration Scheme from Shock Experiments

    Bell, Mary S.


    The shock behavior of calcite and gypsum is important in understanding the Cretaceous/Tertiary event and other terrestrial impacts that contain evaporite sediments in their targets. Most interest focuses on issues of devolatilization to quantify the production of CO2 or SO2 to better understand their role in generating a temporary atmosphere and its effects on climate and biota [e.g., papers in 1,2,3,4]. Devolatilization of carbonate is also important because the dispersion and fragmentation of ejecta is strongly controlled by the expansion of large volumes of gas during the impact process as well [5,6]. Shock recovery experiments for calcite yield seemingly conflicting results: early experimental devolatilization studies [7,8,9] suggested that calcite was substantially outgassed at 30 GPa (> 50%). However, the recent petrographic work of [10,11,12] presented evidence that essentially intact calcite is recovered from 60 GPa experiments. [13] reported results of shock experiments on anhydrite, gypsum, and mixtures of those phases with silica. Their observations indicate little or no devolatilization of anhydrite shocked to 42 GPa and that the fraction of sulfur, by mass, that degassed is approx.10(exp -2) of theoretical prediction. In another (preliminary) report of shock experiments on calcite, anhydrite, and gypsum, [14] observe calcite recrystallization when shock loaded at 61 GPa, only intensive plastic deformation in anhydrite shock loaded at 63 GPa, and gypsum converted to anhydrite when shock loaded at 56 GPa. [15] shock loaded anhydrite and quartz to a peak pressure of 60 GPa. All of the quartz grains were trans-formed to glass and the platy anhydrite grains were completely pseudomorphed by small crystallized anhydrite grains. However, no evidence of interaction between the two phases could be observed and they suggest that recrystallization of anhydrite grains is the result of a solid state transformation. [16] reanalyzed the calcite and anhydrite shock

  19. Removal of phosphorus, fluoride and metals from a gypsum mining leachate using steel slag filters.

    Claveau-Mallet, Dominique; Wallace, Scott; Comeau, Yves


    The objective of this work was to evaluate the capacity of steel slag filters to treat a gypsum mining leachate containing 11-107 mg P/L ortho-phosphates, 9-37 mg/L fluoride, 0.24-0.83 mg/L manganese, 0.20-3.3 zinc and 1.7-8.2 mg/L aluminum. Column tests fed with reconstituted leachates were conducted for 145-222 days and sampled twice a week. Two types of electric arc furnace (EAF) slags and three filter sequences were tested. The voids hydraulic retention time (HRT(v)) of columns ranged between 4.3 and 19.2 h. Precipitates of contaminants present in columns were sampled and analyzed with X-ray diffraction at the end of tests. The best removal efficiencies over a period of 179 days were obtained with sequential filters that were composed of Fort Smith EAF slag operated at a total HRT(v) of 34 h which removed 99.9% of phosphorus, 85.3% of fluoride, 98.0% of manganese and 99.3% of zinc. Mean concentration at this system's effluent was 0.04 mg P/L ortho-phosphates, 4 mg/L fluoride, 0.02 mg/L manganese, 0.02 zinc and 0.5 mg/L aluminum. Thus, slag filters are promising passive and economical systems for the remediation of mining effluents. Phosphorus was removed by the formation of apatite (hydroxyapatite, Ca(5)(PO(4))(3)OH or fluoroapatite, Ca(5)(PO(4))(3)F) as confirmed by visual and X-ray diffraction analyses. The growth rate of apatite was favored by a high phosphorus concentration. Calcite crystals were present in columns and appeared to be competing for calcium and volume needed for apatite formation. The calcite crystal growth rate was higher than that of apatite crystals. Fluoride was removed by precipitation of fluoroapatite and its removal was favored by a high ratio of phosphorus to fluoride in the wastewater.

  20. Moisture parameters and fungal communities associated with gypsum drywall in buildings.

    Dedesko, Sandra; Siegel, Jeffrey A


    Uncontrolled excess moisture in buildings is a common problem that can lead to changes in fungal communities. In buildings, moisture parameters can be classified by location and include assessments of moisture in the air, at a surface, or within a material. These parameters are not equivalent in dynamic indoor environments, which makes moisture-induced fungal growth in buildings a complex occurrence. In order to determine the circumstances that lead to such growth, it is essential to have a thorough understanding of in situ moisture measurement, the influence of building factors on moisture parameters, and the levels of these moisture parameters that lead to indoor fungal growth. Currently, there are disagreements in the literature on this topic. A literature review was conducted specifically on moisture-induced fungal growth on gypsum drywall. This review revealed that there is no consistent measurement approach used to characterize moisture in laboratory and field studies, with relative humidity measurements being most common. Additionally, many studies identify a critical moisture value, below which fungal growth will not occur. The values defined by relative humidity encompassed the largest range, while those defined by moisture content exhibited the highest variation. Critical values defined by equilibrium relative humidity were most consistent, and this is likely due to equilibrium relative humidity being the most relevant moisture parameter to microbial growth, since it is a reasonable measure of moisture available at surfaces, where fungi often proliferate. Several sources concur that surface moisture, particularly liquid water, is the prominent factor influencing microbial changes and that moisture in the air and within a material are of lesser importance. However, even if surface moisture is assessed, a single critical moisture level to prevent fungal growth cannot be defined, due to a number of factors, including variations in fungal genera and

  1. Characterization and precipitation mechanism of α-calcium sulfate hemihydrate growing out of FGD gypsum in salt solution

    YANG LiuChun; GUAN BaoHong; WU ZhongBiao


    Alpha-calcium sulfate hemihydrate (α-HH) has been prepared from flue gas desulfurization (FGD)gypsum with salt solution method under atmospheric pressure. X-ray diffraction (XRD), thermogra-vimetry and differential scanning calorimetry (TG-DSC), optical micrograph, X-ray photoelectron spec-troscopy (XPS), energy dispersive spectrometry (EDS), and scanning electron microscopy (SEM) have been employed to characterize the α-HH crystals, based on which the formation and growth mecha-nisms of the a-HH crystals have been discussed. The results show that FGD gypsum can be success-fully transformed into high purity α-HH in salt solution under mild conditions, and that a dissolu-tion-recrystallization route is most probably adopted by this transition. The growth of a-HH crystals in salt solution demonstrates a preferred direction along [001] and results in a bundle-of-sheets or bun-dle-of-raphide texture. The characteristics revealed in this study can help to understand and control the growth of the α-HH crystal from solution.

  2. Characterization and precipitation mechanism of α-calcium sulfate hemihydrate growing out of FGD gypsum in salt solution


    Alpha-calcium sulfate hemihydrate (α-HH) has been prepared from flue gas desulfurization (FGD) gypsum with salt solution method under atmospheric pressure. X-ray diffraction (XRD),thermogra-vimetry and differential scanning calorimetry (TG-DSC),optical micrograph,X-ray photoelectron spec-troscopy (XPS),energy dispersive spectrometry (EDS),and scanning electron microscopy (SEM) have been employed to characterize the α-HH crystals,based on which the formation and growth mecha-nisms of the α-HH crystals have been discussed. The results show that FGD gypsum can be success-fully transformed into high purity α-HH in salt solution under mild conditions,and that a dissolu-tion-recrystallization route is most probably adopted by this transition. The growth of α-HH crystals in salt solution demonstrates a preferred direction along [001] and results in a bundle-of-sheets or bun-dle-of-raphide texture. The characteristics revealed in this study can help to understand and control the growth of the α-HH crystal from solution.

  3. Study of heat and mass transfer of water evaporation in a gypsum board subjected to natural convection

    Zannouni, K.; El Abrach, H.; Dhahri, H.; Mhimid, A.


    The present paper reports a numerical study to investigate the drying of rectangular gypsum sample based on a diffusive model. Both vertical and low sides of the porous media are treated as adiabatic and impermeable surfaces plate. The upper face of the plate represents the permeable interface. The energy equation model is based on the local thermal equilibrium assumption between the fluid and the solid phases. The lattice Boltzmann method (LBM) is used for solving the governing differential equations system. The obtained numerical results concerning the moisture content and the temperature within a gypsum sample were discussed. A comprehensive analysis of the influence of the mass transfer coefficient, the convective heat transfer coefficient, the external temperature, the relative humidity and the diffusion coefficient on macroscopic fields are also investigated. They all presented results in this paper and obtained in the stable regime correspond to time superior than 4000 s. Therefore the numerical error is inferior to 2%. The experimental data and the descriptive information of the approach indicate an excellent agreement between the results of our developed numerical code based on the LBM and the published ones.

  4. The Distribution of Rock Salt and Gypsum in Sequence Stratigraphic Framework—A Case in Jialingjiang Formation in Chongqing

    Caixa, Gao; Jun, Yi; Junjiang, Su; Yongqin, Zhang; Bo, Li


    The Jialingjiang Formation of the Lower Triassic in the eastern Sichuan Basin is subdivided into four members. The first and third members are featured with limestone, while the second and forth members which are clipped with gypsum and halite are characterized by dolomite and limy dolomite. At the same time, the second and forth members are the main geothermal reservoir in Chongqing area. Two sequence boundaries represented by regional unconformities and the lithology-lithofacies transition surface are recognized in the Jialingjiang formation based on outcrop and borehole data analysis. A total of two third-order sequences are subdivided in the Jialingjiang formation, and they are subcorrelated to the intervals of Member 1 to Member 2, Member 3 to Member 4, respectively. Each sequence is further subdivided into lacustrine transgresive system tract (TST) and highstand system tract (HST) according to variation in lithology and lithofacies. The sea level change is the main factor to control the sequence development. With the sea level change, the middle and late periods of HST in sequence are the favorable periods of the development of rock salt and gypsum.

  5. Study of heat and mass transfer of water evaporation in a gypsum board subjected to natural convection

    Zannouni, K.; El Abrach, H.; Dhahri, H.; Mhimid, A.


    The present paper reports a numerical study to investigate the drying of rectangular gypsum sample based on a diffusive model. Both vertical and low sides of the porous media are treated as adiabatic and impermeable surfaces plate. The upper face of the plate represents the permeable interface. The energy equation model is based on the local thermal equilibrium assumption between the fluid and the solid phases. The lattice Boltzmann method (LBM) is used for solving the governing differential equations system. The obtained numerical results concerning the moisture content and the temperature within a gypsum sample were discussed. A comprehensive analysis of the influence of the mass transfer coefficient, the convective heat transfer coefficient, the external temperature, the relative humidity and the diffusion coefficient on macroscopic fields are also investigated. They all presented results in this paper and obtained in the stable regime correspond to time superior than 4000 s. Therefore the numerical error is inferior to 2%. The experimental data and the descriptive information of the approach indicate an excellent agreement between the results of our developed numerical code based on the LBM and the published ones.

  6. [Application of gypsum-bonded investment containing niobium carbide on casting of alloy for metal-ceramic restoration].

    Tsuruta, S; Ban, S; Hasegawa, J; Hayashi, S; Iiyama, K; Yamamura, Y


    Experimental gypsum-bonded investments containing 0.5-5.0 wt% NbC were prepared by mechanical mixing of each powder. Setting and thermal expansion measurement, compressive strength and casting accuracy for Ni-Cr alloy for metal-ceramic restoration were investigated. Analysis of NbC during heating was carried out by X-ray diffraction, TG-DTA and SEM. NbC was oxidized to Nb2O5 with a volume change between 300-600 degrees C, as in the following equation: 2NbC + 4 1/2O2----Nb2O5 + 2CO2 The theoretical volume of 1/2Nb2O5 calculated from the lattice constants according to JCPDS file was approximately 4 times larger than that of NbC. The experimental investments of 70 wt% cristobalite and 30 wt% gypsum containing 2.0, 3.0 and 5.0 wt% NbC showed large thermal expansion of 7.0, 10.0 and 13.0% respectively. The investment containing 2.0 wt% NbC showed nearly the same casting accuracy for Ni-Cr alloys for metal-ceramic restoration as the commercial phosphate-bonded investment.

  7. Behavior of aluminum, arsenic, and vanadium during the neutralization of red mud leachate by HCl, gypsum, or seawater.

    Burke, Ian T; Peacock, Caroline L; Lockwood, Cindy L; Stewart, Douglas I; Mortimer, Robert J G; Ward, Michael B; Renforth, Philip; Gruiz, Katalin; Mayes, William M


    Red mud leachate (pH 13) collected from Ajka, Hungary is neutralized to 99% Al is removed from solution during the formation of an amorphous boehmite-like precipitate and dawsonite. Minor amounts of As (24%) are also removed from solution via surface adsorption of As onto the Al oxyhydroxides. Gypsum addition to red mud leachate results in the precipitation of calcite, both in experiments and in field samples recovered from rivers treated with gypsum after the October 2010 red mud spill. Calcite precipitation results in 86% Al and 81% As removal from solution, and both are nonexchangeable with 0.1 mol L(-1) phosphate solution. Contrary to As associated with neoformed Al oxyhydroxides, EXAFS analysis of the calcite precipitates revealed only isolated arsenate tetrahedra with no evidence for surface adsorption or incorporation into the calcite structure, possibly as a result of very rapid As scavenging by the calcite precipitate. Seawater neutralization also resulted in carbonate precipitation, with >99% Al and 74% As removed from solution during the formation of a poorly ordered hydrotalcite phase and via surface adsorption to the neoformed precipitates, respectively. Half the bound As could be remobilized by phosphate addition, indicating that As was weakly bound, possibly in the hydrotalcite interlayer. Only 5-16% V was removed from solution during neutralization, demonstrating a lack of interaction with any of the neoformed precipitates. High V concentrations are therefore likely to be an intractable problem during the treatment of red mud leachates.

  8. Utilization of desulfurization gypsum to producing SO{sub 2} and CaO in multi-stage fluidized bed

    Miao, Zhu; Wang, Tao; Yang, Hairui; Zhang, Hai; Zhang, Zuyi [Tsinghua Univ., Beijing (China). Dept. of Thermal Engineering; Ministry of Education, Beijing (China). Key Lab. for Thermal Science and Power Engineering


    With emission control becomes more and more stringent, flue gas desulphurization (FGD) is commonly employed for desulfurization. However, the product of FGD, gypsum, causes the unexpected environmental problems. How to utilize the byproduct of FGD effectively and economically is a challenging task. This paper proposed the new technical process to produce SO{sub 2} and CaO by reducing the gypsum in multi-stage fluidized bed reactor with different atmosphere. In addition, some preliminary experiments were carried out in PTGA. The results show that CO concentration has little effect on the initial decomposing temperature, but affect the decomposing rate of phosphogypsum obviously. The decomposing product composed of CaS and CaO simultaneously. The ratio of the two products was determined by CO concentration. Lower CO content benefits to produce more CO product and more SO{sub 2}. The decomposition reaction of phosphogypsum in reducing atmosphere is parallel competition reaction. Therefore, it is necessary to eliminate the effect of CaS and other byproduct efficiently by the new technology, which utilize multi-atmosphere in multistage fluidized bed reactors.

  9. 添加剂对脱硫石膏汞热稳定性的影响%Effects of Additives on Thermal Stability of Mercury in Desulfurization Gypsum

    邱勇; 张璧; 邹仁杰; 余桥; 徐萍; 吴辉; 罗光前; 姚洪


    Additives can inhibit Hg0 re-emission in WFGD and cause mercury enrichment in gypsum,but mercury in gypsum will be released in heat treatment processes.Experiments were conducted to study the effect of three addi-tives on the promotion of mercury content in gypsum,the thermal stability of mercury in heat treatment processes, and the change of mercury compound species in gypsum.The results showed that when NaHS,TMT and DTCR were added to gypsum slurry,the mercury content in gypsum was significantly increased,and that mercury mainly exisited in the form of HgS,Hg3(TMT)2 and Hg(DTCR)2. The peak of decomposition temperature and the range of decomposition temperature gradually decreased in the order of HgS,Hg3(TMT)2 and Hg(DTCR)2.The residual mercury content in gypsum was gradually reduced with the addition of adding NaHS,TMT and DTCR after heatedat 200,℃ for 2,h.The lowest residual mercury content in gypsum was 182.0 ng/g,and the mercury release rate was increased to 90% with the addition of DTCR.%添加剂能抑制湿法烟气脱硫(WFGD)系统汞释放,被添加剂富集到石膏的汞在石膏热处理过程会再释放.实验研究了3种 WFGD 抑制汞释放添加剂对汞在石膏中富集的促进作用、石膏中汞化合物变化和石膏热处理过程汞稳定性的影响.结果表明,NaHS、TMT和DTCR的添加使石膏汞含量显著升高,使石膏中汞分别以HgS、Hg3(TMT)2和 Hg(DTCR)2形式存在,其分解峰值温度与分解温度范围依次减小;在200,℃热处理2,h 后石膏的剩余汞含量也依次降低,最低汞质量分数为182.0,ng/g,而且DTCR使汞释放率增加到90%,.

  10. Evidence for micro-biological induction of {101} montmartre twinning of gypsum (CaSO 4 ⋯ 2H 2O)

    Cody, A. M.; Cody, R. D.


    Natural gypsum crystals twinned on d{101} have been found almost exclusively in deposits from saline lakes and secondary mine alterations. The presence of α-amylase, an enzyme excreted into soils and water by bacteria, fungi, algae, and plant roots, was found to induce d{101} twinning of gypsum crystals formed by diffusion in laboratory growth experiments. From this evidence, extensive deposits of d{101} twinned crystals such as those of the Paris Basin are proposed to form in the α-amylase concentrations that results from certain microbial blooms.

  11. Incorporation of gypsum waste in ceramic block production: Proposal for a minimal battery of tests to evaluate technical and environmental viability of this recycling process.

    Godinho-Castro, Alcione P; Testolin, Renan C; Janke, Leandro; Corrêa, Albertina X R; Radetski, Claudemir M


    Civil engineering-related construction and demolition debris is an important source of waste disposed of in municipal solid waste landfills. After clay materials, gypsum waste is the second largest contributor to the residential construction waste stream. As demand for sustainable building practices grows, interest in recovering gypsum waste from construction and demolition debris is increasing, but there is a lack of standardized tests to evaluate the technical and environmental viability of this solid waste recycling process. By recycling gypsum waste, natural deposits of gypsum might be conserved and high amounts of the waste by-product could be reused in the civil construction industry. In this context, this paper investigates a physical property (i.e., resistance to axial compression), the chemical composition and the ecotoxicological potential of ceramic blocks constructed with different proportions of clay, cement and gypsum waste, and assesses the feasibility of using a minimal battery of tests to evaluate the viability of this recycling process. Consideration of the results for the resistance to axial compression tests together with production costs revealed that the best formulation was 35% of plastic clay, 35% of non-plastic clay, 10% of Portland cement and 20% of gypsum waste, which showed a mean resistance of 4.64MPa. Energy dispersive X-ray spectrometry showed calcium and sulfur to be the main elements, while quartz, gypsum, ettringite and nacrite were the main crystalline compounds found in this formulation. Ecotoxicity tests showed that leachate from this formulation is weakly toxic toward daphnids and bacteria (EC(20%)=69.0 and 75.0, respectively), while for algae and fish the leachate samples were not toxic at the EC(50%) level. Overall, these results show that the addition of 20% of gypsum waste to the ceramic blocks could provide a viable substitute for clay in the ceramics industry and the tests applied in this study proved to be a useful tool


    马跃; 陈勉; 杨春和; 杨沛; 卢运虎; 贾斯博; 金衍


    Because of the coring difficulty in deep-layer salt formation,artificial cores were made according to its field mineral composition. Creep tests were conducted which shows that the natural core and the artificial core with the same mineral composition had the same creep law. In light of this finding,further creep tests of the artificial core were carried under different confining pressures and same temperature,and the effects of contents of different mineral compositions on the creep were obtained. The test results showed that under the same stress and temperature condition,the steady-state creep rate of high-salt salt-gypsum formation was higher,while the high-gypsum salt-gypsum formation was lower. At the same time,the physico-chemical property analysis were conducted for natural core in Caspian Basin,which also verified the above conclusion. The test result was tested in two ultra-deep wells in Keshen block in Tarim oil field and was applied to determination of drill fluid density.%针对深部盐膏岩地层岩芯获取难度大的难题,依据现场岩屑的矿物组分,人工压制盐膏岩试验试样,蠕变试验表明,相同组分的天然岩芯和人造岩芯具有相似的蠕变规律。据此,通过对人造岩芯进行不同围压和相同温度下的蠕变试验,得到各种矿物组分含量对其蠕变的影响。结果表明:在相同应力和温度条件下,盐含量多的复合盐岩的稳态蠕变速率较高,膏含量多的复合盐岩的稳态蠕变速率较低。同时,对滨里海盆地的天然岩芯进行理化性能分析,同样验证了以上的结论。试验结果在塔里木克深区块的超深井得到验证,并指导钻井液密度的合理确定。

  13. Effect of different forms of silica on the physical and mechanical properties of gypsum plaster composites

    Khalil, A. A.


    Full Text Available Gypsum plaster/silica composites prepared by dry blending (0.2-10 % natural sand, silica fume or silica gel and subsequently hydrated. Their physical and mechanical properties, including normal consistency, setting time, apparent porosity, bulk density and compressive strength, were determined after hydration for 7- and 28-days. The results indicated that adding different forms of silica lowered the bulk density and increased the normal consistency, setting time, apparent porosity and, to some limited extent, compressive strength of the composites. This improvement in properties can be attributed to the existence of silica in the interstitial pores in the hardened plaster matrices. While most of the composites revealed only scant rises in compressive strength, their composition was beneficial in so far as it included either a readily available low-cost constituent (sand or industrial by-products. Consequently, the formed plaster-silica composites are of economic value, contribute to a cleaner environment by minimizing waste and can be used for applications where high porosity, lightweight units are required or recommended for low-cost buildings.Se prepararon pastas compuestas de yeso y sílice mediante la mezcla en seco de yeso con distintas proporciones (0,2- 10 % de arena natural, o gel o humo de sílice, procediéndose a continuación a su hidratación. A fin de determinar las propiedades físicas y mecánicas de las pastas, a los 7 y los 28 días de hidratación se hallaron su fluidez, tiempo de fraguado, porosidad aparente, densidad aparente y resistencia a la compresión. Los resultados obtenidos indican que al incorporar las distintas modalidades de sílice a la mezcla, disminuyó la densidad aparente y aumentaron la fluidez, el tiempo de fraguado, la porosidad aparente y, en menor medida, la resistencia a la compresión de las muestras. Se considera que esta mejora de las propiedades del material se debe a la presencia de sílice en los

  14. Determination of Calcium Phase in Sinter Desulfurization Gypsum%烧结脱硫石膏的钙相分析

    张强; 曾波; 涂昀; 万丽云


    建立烧结脱硫石膏的钙相分析方法。根据石灰石浆脱硫工艺的特点,利用脱硫石膏中硫酸钙和亚硫酸钙等钙相的不同特征,用EDTA容量法测定总钙,并用ICP法、红外仪器方法测得硫酸钙、亚硫酸钙、碳酸钙等的含量,再利用差减法计算氧化钙的含量。测定结果的相对标准偏差小于1.5%(n=6),硫酸钙、亚硫酸钙、碳酸钙及氧化钙的加标回收率在97%~100%之间。该方法操作简单、快速,可用于烧结脱硫工艺中烧结脱硫石膏钙相的日常检测,实现对脱硫工艺中各阶段反应产物的准确定量。%The analysis method of sintering desulfurization gypsum calcium phase was established. According to the characteristics of limestone slurry desulfurization process, by the different characteristics of calcium sulfate and calcium sulfite calcium phase desulfurization gypsum, total calcium was determined by EDTA volumetric method, and calcium sulfate, calcium sulfite, calcium carbonate were determined by ICP and infrared instrument method, and then the content of calcium oxide was caculated by differential subtraction. The method had the advantages of simple operation with short time,the relative standard deviations of determination results were less than 1.5%(n=6). The recoveries of calcium sulfate, calcium sulfate,calcium carbonate and calcium oxide were 97%–100%. The method is simple, rapid and can be used for sintering desulfurization process of sintering desulfurization gypsum calcium phase in the daily inspection, implementation of desulfurization technology in various stages of the reaction products accurate quantitative.

  15. Comparison of Four Strong Acids on the Precipitation Potential of Gypsum in Brines During Distillation of Pretreated, Augmented Urine

    Muirhead, Dean; Carrier, Christopher


    In this study, three different mineral acids were substituted for sulfuric acid (H2SO4) in the urine stabilizer solution to eliminate the excess of sulfate ions in pretreated urine and assess the impact on maximum water recovery to avoid precipitation of minerals during distillation. The study evaluated replacing 98% sulfuric acid with 85% phosphoric acid (H3PO4), 37% hydrochloric acid (HCl), or 70% nitric acid (HNO3). The effect of lowering the oxidizer concentration in the pretreatment formulation also was studied. This paper summarizes the test results, defines candidate formulations for further study, and specifies the injection masses required to stabilize urine and minimize the risk of mineral precipitation during distillation. In the first test with a brine ersatz acidified with different acids, the solubility of calcium in gypsum saturated solutions was measured. The solubility of gypsum was doubled in the brines acidified with the alternative acids compared to sulfuric acid. In a second series of tests, the alternative acid pretreatment concentrations were effective at preventing precipitation of gypsum and other minerals up to 85% water recovery from 95th-percentile pretreated, augmented urine. Based on test results, phosphoric acid is recommended as the safest alternative to sulfuric acid. It also is recommended that the injected mass concentration of chromium trioxide solution be reduced by 75% to minimize liquid resupply mass by about 50%, reduce toxicity of brines, and reduce the concentration of organic acids in distillate. The new stabilizer solution formulations and required doses to stabilize urine and prevent precipitation of minerals up to 85% water recovery are given. The formulations in this study were tested on a limited number of artificially augmented urine batches collected from employees at the Johnson Space Center (JSC). This study successfully demonstrated that the desired physical and chemical stability of pretreated urine and brines

  16. Effects of surface application of calcium-magnesium silicate and gypsum on soil fertility and sugarcane yield

    Carlos Alexandre Costa Crusciol


    Full Text Available Lime application recommendations for amendment of soil acidity in sugarcane were developed with a burnt cane harvesting system in mind. Sugarcane is now harvested in most areas without burning, and lime application for amendment of soil acidity in this system in which the sugarcane crop residue remains on the ground has been carried out without a scientific basis. The aim of this study was to evaluate the changes in soil acidity and stalk and sugar yield with different rates of surface application of calcium, magnesium silicate, and gypsum in ratoon cane. The experiment was performed after the 3rd harvest of the variety SP 81-3250 in a commercial green sugarcane plantation of the São Luiz Sugar Mill (47º 25' 33" W; 21º 59' 46" S, located in Pirassununga, São Paulo, in southeast Brazil. A factorial arrangement of four Ca-Mg silicate rates (0, 850, 1700, and 3400 kg ha-1 and two gypsum rates (0 and 1700 kg ha-1 was used in the experiment. After 12 months, the experiment was harvested and technological measurements of stalk and sugar yield were made. After harvest, soil samples were taken at the depths of 0.00-0.05, 0.05-0.10, 0.10-0.20, 0.20-0.40, and 0.40-0.60 m in all plots, and the following determinations were made: soil pH in CaCl2, organic matter, P, S, K, Ca, Mg, H+Al, Al, Si, and base saturation. The results show that the application of gypsum reduced the exchangeable Al3+ content and Al saturation below 0.05 m, and increased the Ca2+ concentration in the whole profile, the Mg2+ content below 0.10 m, K+ below 0.4 m, and base saturation below 0.20 m. This contributed to the effect of surface application of silicate on amendment of soil acidity reaching deeper layers. From the results of this study, it may be concluded that the silicate rate recommended may be too low, since the greater rates used in this experiment showed greater reduction in soil acidity, higher levels of nutrients at greater depths and an increase in stalk and sugar

  17. Stabilization of FGD gypsum for its disposal in landfills using amorphous aluminium oxide as a fluoride retention additive.

    Alvarez-Ayuso, E; Querol, X


    The applicability of amorphous aluminium oxide as a fluoride retention additive to flue gas desulphurisation (FGD) gypsum was studied as a way of stabilizing this by-product for its disposal in landfills. Using a batch method the sorption behaviour of amorphous aluminium oxide was evaluated at the pH (about 6.5) and background electrolyte conditions (high chloride and sulphate concentrations) found in FGD gypsum leachates. It was found that fluoride sorption on amorphous aluminium oxide was a very fast process with equilibrium attained within the first half an hour of interaction. The sorption process was well described by the Langmuir model, offering a maximum fluoride sorption capacity of 61.7 mg g(-1). Fluoride sorption was unaffected by chloride co-existing ions, while slightly decreased (about 20%) by competing sulphate ions. The use of amorphous aluminium oxide in the stabilization of FGD gypsum proved to greatly decreased its fluoride leachable content (in the range 5-75% for amorphous aluminium oxide doses of 0.1-2%, as determined by the European standard EN 12457-4 [EN-12457-4 Characterization of waste-leaching-compliance test for leaching of granular waste materials and sludges-Part 4: one stage batch test at a liquid to solid ratio of 10 l/kg for materials with particle size below 10mm (without or with size reduction)]), assuring the characterization of this by-product as a waste acceptable at landfills of non-hazardous wastes according to the Council Decision 2003/33/EC [Council Decision 2003/33/EC of 19 December 2002. Establishing criteria and procedures for the acceptance of waste at landfills pursuant to Article 16 of and Annex II to Directive 1999/31/EC] on landfill of wastes. Furthermore, as derived from column leaching studies, the proposed stabilization system proved to be highly effective in simulated conditions of disposal, displaying a fluoride leaching reduction value about 81% for an amorphous aluminium oxide added amount of 2%.

  18. Optimization of Enzyme-Mediated Calcite Precipitation as a Soil-Improvement Technique: The Effect of Aragonite and Gypsum on the Mechanical Properties of Treated Sand

    Heriansyah Putra


    Full Text Available The effectiveness of magnesium as a substitute material in enzyme-mediated calcite precipitation was evaluated. Magnesium sulfate was added to the injecting solution composed of urea, urease, and calcium chloride. The effect of the substitution on the amount of precipitated materials was evaluated through precipitation tests. X-ray powder diffraction and scanning electron microscopy analyses were conducted to examine the mineralogical morphology of the precipitated minerals and to determine the effect of magnesium on the composition of the precipitated materials. In addition to calcite, aragonite and gypsum were formed as the precipitated materials. The effect of the presence of aragonite and gypsum, in addition to calcite, as a soil-improvement technique was evaluated through unconfined compressive strength tests. Soil specimens were prepared in polyvinyl chloride cylinders and treated with concentration-controlled solutions, which produced calcite, aragonite, and gypsum. The mineralogical analysis revealed that the low and high concentrations of magnesium sulfate effectively promoted the formation of aragonite and gypsum, respectively. The injecting solutions which produced aragonite and calcite brought about a significant improvement in soil strength. The presence of the precipitated materials, comprising 10% of the soil mass within a treated sand, generated a strength of 0.6 MPa.

  19. Gypsum-Catalyzed One-Pot Synthesis of 3,4-Dihydropyrimidin-2(1H Under Solvent-Free Conditions

    Taoues Boumoud


    Full Text Available In view of the emerging importance of the green chemistry principles in chemical and pharmaceutical industries, we disclose, herein, a new economic approach producing the biologically active dihydropyrimidinones in good yields using the solventless one-pot Biginelli condensation in the presence of gypsum as an environmental friendly and recycled catalyst.

  20. Land subsidence and caprock dolines caused by subsurface gypsum dissolution and the effect of subsidence on the fluvial system in the Upper Tigris Basin (between Bismil Batman, Turkey)

    Doğan, Uğur


    Karstification-based land subsidence was found in the Upper Tigris Basin with dimensions not seen anywhere else in Turkey. The area of land subsidence, where there are secondary and tertiary subsidence developments, reaches 140 km 2. Subsidence depth ranges between 40 and 70 m. The subsidence was formed as a result of subsurface gypsum dissolution in Lower Miocene formation. Although there are limestones together with gypsum and Eocene limestone below them in the area, a subsidence with such a large area is indicative of karstification in the gypsum. The stratigraphical cross-sections taken from the wells and the water analyses also verify this fact. The Lower Miocene gypsum, which shows confined aquifer features, was completely dissolved by the aggressive waters injected from the top and discharged through by Zellek Fault. This resulted in the development of subsidence and formation of caprock dolines on loosely textured Upper Miocene-Pliocene cover formations. The Tigris River runs through the subsidence area between Batman and Bismil. There are four terrace levels as T1 (40 m), T2 (30 m), T3 (10 m) and T4 (4-5 m) in the Tigris River valley. It was also found that there were some movements of the levels of the terraces in the valley by subsidence. The subsidence developed gradually throughout the Quaternary; however no terrace was formed purely because of subsidence.

  1. Fibrous gypsum veins as diffuse features and within fault zones: the case study of the Pisco Basin (Ica desert, southern Peru)

    Rustichelli, Andrea; Di Celma, Claudio; Tondi, Emanuele; Baud, Patrick; Vinciguerra, Sergio


    New knowledge on patterns of fibrous gypsum veins, their genetic mechanisms, deformation style and weathering are provided by a field- and laboratory-based study carried out on the Neogene to Quaternary Pisco Basin sedimentary strata (porous sandstones, siltstones and diatomites) exposed in the Ica desert, southern Peru. Gypsum veins vary considerably in dimensions, attitudes and timing and can develop in layered and moderately fractured rocks also in the absence of evaporitic layers. Veins occur both as diffuse features, confined to certain stratigraphic levels, and localised within fault zones. Arrays formed by layer-bounded, mutually orthogonal sets of steeply-dipping gypsum veins are reported for the first time. Vein length, height and spacing depend on the thickness of the bed packages in which they are confined. Within fault zones, veins are partly a product of faulting but also inherited layer-bounded features along which faults are superimposed. Due to the different petrophysical properties with respect to the parent rocks and their susceptibility to textural and mineralogical modifications, water dissolution and rupture, gypsum veins may have a significant role in geofluid management. Depending on their patterns and grade of physical and chemical alteration, veins may influence geofluid circulation and storage, acting as barriers to flow and possibly also as conduits.

  2. Easily altered minerals and reequilibrated fluid inclusions provide extensive records of fluid and thermal history: gypsum pseudomorphs of the Tera Group, Tithonian-Berriasian, Cameros Basin

    González-Acebrón, Laura; Goldstein, Robert; Mas, Ramon; Arribas, Jose


    This study reports a complex fluid and thermal history using petrography, electron microprobe, isotopic analysis and fluid inclusions in replacement minerals within gypsum pseudomorphs in Tithonian-Berriasian lacustrine deposits in Northern Spain. Limestones and dolostones, formed in the alkaline lakes, contain lenticularly shaped gypsum pseudomorphs, considered to form in an evaporative lake. The gypsum was replaced by quartz and non-ferroan calcite (Ca-2), which partially replaces the quartz. Quartz contains solid inclusions of a preexisting non-ferroan calcite (Ca-1), anhydrite and celestine. High homogenization temperatures (T h) values and inconsistent thermometric behaviour within secondary fluid inclusion assemblages in quartz (147-351°C) and calcite (108-352°C) indicate high temperatures after precipitation and entrapment of lower temperature FIAs. Th are in the same range as other reequilibrated fluid inclusions from quartz veins in the same area that are related to Cretaceous hydrothermalism. Gypsum was replaced by anhydrite, likely during early burial. Later, anhydrite was partially replaced by Ca-1 associated with intermediate burial temperatures. Afterward, both anhydrite and Ca-1 were partially replaced by quartz and this by Ca-2. All were affected during higher temperature hydrothermalism and a CO2-H2O fluid. Progressive heating and hydrothermal pulses, involving a CO2-H2O fluid, produce the reequilibration of the FIAs, which was followed by uplift and cooling.

  3. Gypsum (CaSO4·2H2O Scaling on Polybenzimidazole and Cellulose Acetate Hollow Fiber Membranes under Forward Osmosis

    Tai-Shung Chung


    Full Text Available We have examined the gypsum (CaSO4·2H2O scaling phenomena on membranes with different physicochemical properties in forward osmosis (FO processes. Three hollow fiber membranes made of (1 cellulose acetate (CA, (2 polybenzimidazole (PBI/polyethersulfone (PES and (3 PBI-polyhedral oligomeric silsesquioxane (POSS/polyacrylonitrile (PAN were studied. For the first time in FO processes, we have found that surface ionic interactions dominate gypsum scaling on the membrane surface. A 70% flux reduction was observed on negatively charged CA and PBI membrane surfaces, due to strong attractive forces. The PBI membrane surface also showed a slightly positive charge at a low pH value of 3 and exhibited a 30% flux reduction. The atomic force microscopy (AFM force measurements confirmed a strong repulsive force between gypsum and PBI at a pH value of 3. The newly developed PBI-POSS/PAN membrane had ridge morphology and a contact angle of 51.42° ± 14.85° after the addition of hydrophilic POSS nanoparticles and 3 min thermal treatment at 95 °C. Minimal scaling and an only 1.3% flux reduction were observed at a pH value of 3. Such a ridge structure may reduce scaling by not providing a locally flat surface to the crystallite at a pH value of 3; thus, gypsum would be easily washed away from the surface.

  4. Estimation of radioactivity level and associated radiological hazards of limestone and gypsum used as raw building materials in Rawalpindi/Islamabad region of Pakistan.

    Gul, Rahmat; Ali, Safdar; Hussain, Manzur


    This study was undertaken to asses the radioactivity level of limestone and gypsum and its associated radiological hazard due to the presence of naturally occurring radioactive materials. Representative samples of limestone and gypsum were collected from cement factories located in the Rawalpindi/Islamabad region of Pakistan and were analysed by using an N-type high-purity germanium detector of 80 % relative efficiency. The average activity concentration of (40)K, (226)Ra and (232)Th were 60.22±3.47, 29.25±5.23 and 4.07±3.31 Bq kg(-1), respectively, in limestone and 70.86±4.1, 5.01±2.10 and 4.49±3.1 Bq kg(-1), respectively, in gypsum. The radiological hazard parameters radium equivalent activities, absorbed dose rate in air, external hazard index, internal hazard index, annual effective dose equivalent, gamma index and alpha index were computed. The results of the average activity concentrations of (40)K, (226)Ra and (232)Th and radiological hazard parameters were within the range of the reported average worldwide/United Nations Scientific Committee on the Effect of Atomic Radiation values. It is concluded that limestone and gypsum used in the Rawalpindi/Islamabad region does not pose any excessive radiological health hazard as a building raw materials and in industrial uses.

  5. A Scanning Transmission X-ray Microscopy Study of Cubic and Orthorhombic C3A and Their Hydration Products in the Presence of Gypsum

    Vanessa Rheinheimer


    Full Text Available This paper shows the microstructural differences and phase characterization of pure phases and hydrated products of the cubic and orthorhombic (Na-doped polymorphs of tricalcium aluminate (C3A, which are commonly found in traditional Portland cements. Pure, anhydrous samples were characterized using scanning transmission X-ray microscopy (STXM, X-ray photoelectron spectroscopy (XPS and X-ray diffraction (XRD and demonstrated differences in the chemical and mineralogical composition as well as the morphology on a micro/nano-scale. C3A/gypsum blends with mass ratios of 0.2 and 1.9 were hydrated using a water/C3A ratio of 1.2, and the products obtained after three days were assessed using STXM. The hydration process and subsequent formation of calcium sulfate in the C3A/gypsum systems were identified through the changes in the LIII edge fine structure for Calcium. The results also show greater Ca LII binding energies between hydrated samples with different gypsum contents. Conversely, the hydrated samples from the cubic and orthorhombic C3A at the same amount of gypsum exhibited strong morphological differences but similar chemical environments.

  6. Pharmacological properties of traditional medicines. XXV. Effects of ephedrine, amygdalin, glycyrrhizin, gypsum and their combinations on body temperature and body fluid.

    Yuan, D; Komatsu, K; Cui, Z; Kano, Y


    Effects of ephedrine, amygdalin, glycyrrhizin, gypsum and their combinations on body temperature and body fluid were studied in rats using the method developed in our previous reports. Ephedrine significantly increased respiratory evaporative water loss and heat loss in response to a marked elevation of body temperature. There was a small but significant increase in body temperature when amygdalin was orally given rats at a dose of 46.32 mg/kg. Glycyrrhizin and gypsum were unable to affect body temperature. However, gypsum was able to prevent the increased action of ephedrine on body temperature, amygdalin exhibited a preventive tendency to it, and glycyrrhizin did not affect it. The results are in good agreement with classical claims of Makyo-kanseki-to and the related crude drugs in traditional medicine. Moreover, a combination of the four components reproduced the effects of Makyo-kanseki-to on body temperature and body fluid. This report suggests that the co-administration of ephedrine and gypsum is physiologically more desirable than ephedrine alone for dry-type asthmatic patients with a fever. Also, it experimentally supports the clinical efficacy of Makyo-kanseki-to.

  7. Well logging identification of gypsum cap rocks in middle-upper Yangtze region%中上扬子区膏岩盖层的测井识别

    冯琼; 魏水建


    针对中、上扬子区膏岩盖层测井响应特征,充分利用地质、录井、岩心分析、测井等资料,采用岩心刻度测井的方法,建立了膏岩盖层参数测井解释模型,并对该区膏岩盖层进行了测井解释与评价;建立了一套适合川东北地区膏岩盖层的测井识别方法,从而实现了盖层从定性识别到盖层参数的定量评价,为盖层的地球物理预测研究提供了重要的基础参数.%Based on well logging response characteristics of gypsum cap rocks in the middle- upper Yangtze region, with geology, well logging, core analysis and logging data, it was established in this paper a logging interpretation model of gypsum cap rock parameters using the core calibration logging method.The gypsum cap rocks in the study region were interpreted and evaluated. A new set of logging identification method suitable for gypsum cap rocks in the Northeast Sichuan Basin was put forward. The qualitative identification and the quantitative evaluation of cap rocks were done, offering important basis parameters for the geophysical prediction researches of cap rocks.

  8. Preparation and Properties of Lemon Gypsum/PP Composites%柠檬石膏/聚丙烯复合材料的制备与性能

    朱道吉; 任凤梅; 周正发; 徐卫兵


    The effects of lemon gypsum and the surface treatment lemon gypsum on the mechanical properties,micro morphology,crystallinity and melting point of PP composites were investigated.The results indicate that the tensile strength,bending strength,and bending modulus of the composites are increased,and the surface treatment effectiveness of aluminum coupling agent and titanate coupling agent is good.The SEM results show that dispersion of the lemon gypsum treated by coupling agent in PP is better than that of surface untreatment lemon gypsum in PP.The DSC results show that the crystallinity of PP is increased,while the melt point of PP is almost unchange when PP is filled with lemon gypsum.The crystallinity and melt point of PP are not influenced by surface treatment of lemon gypsum,compared with those of PP filled by surface untreatment lemon gypsum.%研究了柠檬石膏及表面处理柠檬石膏对聚丙烯(PP)复合材料的力学性能、微观形貌、结晶度、熔点的影响.结果表明:柠檬石膏的加入使复合材料的拉伸强度、弯曲强度和弯曲模量有不同程度提高,用钛酸酯和铝酸酯偶联剂对柠檬石膏进行表面处理后效果较好.扫描电镜(SEM)分析结果显示经过偶联剂表面处理的柠檬石膏在PP中分散的较未处理的柠檬石膏均匀.差示扫描量热(DSC)结果表明:柠檬石膏的加入在提高PP的结晶度同时,对复合材料的熔点几乎没有影响;相比未表面处理的柠檬石膏,表面处理后的柠檬石膏对复合材料中PP的结晶度和熔点均没有显著影响.

  9. Manufacture of ammonium sulfate fertilizer from gypsum-rich byproduct of flue gas desulfurization - A prefeasibility cost estimate

    Chou, I.-Ming; Rostam-Abadi, M.; Lytle, J.M.; Achorn, F.P.


    Costs for constructing and operating a conceptual plant based on a proposed process that converts flue gas desulfurization (FGD)-gypsum to ammonium sulfate fertilizer has been calculated and used to estimate a market price for the product. The average market price of granular ammonium sulfate ($138/ton) exceeds the rough estimated cost of ammonium sulfate from the proposed process ($111/ ton), by 25 percent, if granular size ammonium sulfate crystals of 1.2 to 3.3 millimeters in diameters can be produced by the proposed process. However, there was at least ??30% margin in the cost estimate calculations. The additional costs for compaction, if needed to create granules of the required size, would make the process uneconomical unless considerable efficiency gains are achieved to balance the additional costs. This study suggests the need both to refine the crystallization process and to find potential markets for the calcium carbonate produced by the process.

  10. Conversion of calcium sulphide to calcium carbonate during the process of recovery of elemental sulphur from gypsum waste.

    de Beer, M; Maree, J P; Liebenberg, L; Doucet, F J


    The production of elemental sulphur and calcium carbonate (CaCO3) from gypsum waste can be achieved by thermally reducing the waste into calcium sulphide (CaS), which is then subjected to a direct aqueous carbonation step for the generation of hydrogen sulphide (H2S) and CaCO3. H2S can subsequently be converted to elemental sulphur via the commercially available chemical catalytic Claus process. This study investigated the carbonation of CaS by examining both the solution chemistry of the process and the properties of the formed carbonated product. CaS was successfully converted into CaCO3; however, the reaction yielded low-grade carbonate products (i.e. 99 mass% as CaCO3) or precipitated calcium carbonate (PCC).

  11. 分光光度法快速测定磷石膏的溶解度%Spectrophotometric Method for Measuring Solubility of Phosphorus Gypsum

    马保国; 侯伟; 茹晓红; 谭洪波; 石明明; 孔维; 邹开波


    The main ingredient of phosphorus gypsum was dehydrate calcium sulphate, the calcium sulphate contains large amounts of sulfate when it dissolved in solution. Through determination the content of sulfate radicals, then calculate the content of phosphorus gypsum in the solution, thus find the solubility of the phosphorus gypsum. Barium chro-mate spectrophotometry was adopted to determine the solubility of the phosphorus gypsum in the calcium sulphate solu tion. At 420 nm wave length, when the mass concentrations of calcium sulphate is at 0-0. 50 mg/mL and it has a linear relation with chromate radicals. Compared with traditional methods, the reliability of the experimental results can be verified. The method is simple, rapid, the Barium chromate spectrophotometry method is applied to the determine the solubility of phosphorus gypsum. It has advantages of simplicity and strong feasibility, which can satisfy the To meet the requirement of determination.%磷石膏主要成分为二水硫酸钙,硫酸钙溶解后溶液中含有大量的硫酸根,通过测定硫酸根的含量,可以计算出溶液中磷石膏的含量,进而求出磷石膏对应的溶解度.用铬酸钡分光光度法测定磷石膏的溶解度,在420 nm波长处,硫酸钙为0~0.50 mg/mL时与铬酸根吸光度呈线性关系.通过与传统的分析方法对比,可以验证实验结果的可靠性.该方法简单、快速、可行性强,可用于测定磷石膏的溶解度,可以满足测定要求.

  12. Study on property ,of foam FGD-gypsum concrete block%脱硫石膏泡沫凝土砌块的性能研究

    谢建海; 向仁科


    以脱硫石膏为主要材料,通过添加水泥、矿渣粉、自制添加剂改性,外掺少量CaO、促凝剂和发泡剂制备出了不同密度等级的脱硫石膏泡沫混凝土砌块。研究了不同外加剂掺量对胶凝材料初终凝时间和力学性能的影响;利用导热系数测定仪测试了石膏泡沫混凝土的导热系数;对脱硫石膏基胶凝材料水化产物机理进行了分析。研究表明:脱硫石膏泡沫混凝土砌块与其他类型砌块相比具有强度高、耐抽陛好、导热系数低等优良性能。%The foam FGD-gypsum concrete blocks in different density are made of desulphurization gypsum, slag, Portland cement, self-made modifier, small amount of CaO, c the flue gas oagulator and foaming agent . The influence of different additives on the initial-final coagulation times and mechanics performance of gelled material are test. The thermal conductivity of foam gypsum concrete is test by coefficient of thermal conductivity detector. And the hydration products mechanism of desulphurization gypsum based gelled material is analyzed. The results indicate that the foam FGD-gypsum concrete block are of higher strength, better water impermeability and lower thermal conductivity comparing with others.

  13. the Research Progress of Water-Proofing Gypsum Block%石膏砌块耐水性研究进展

    黄丹; 杨林; 曹建新


    Owing to gypsum block's disadvantage of poor water-proofing, the paper summarized some methods which can improve gypsum block's disadvantage by looking up lots of literatures. The results showed that there were mainly three methods: one was adding the activated pozzolana to gypsum; the other was adding organic water repellents; thirdly, the two materials (the activated pozzolana and organic water repellents) were added to gypsum at some rate. The first method was the most economical. If the gypsum block could be water-proofing only by adding the activated pozzolana, the prospect would be broad.%石膏砌块具有耐水性差的缺点,从而限制其使用领域.基于这一问题,文章总结了目前耐水石膏砌块处理技术的研究进展,其中采用在建筑石膏中掺入有机防水剂与活性火山灰质等材料制备耐水石膏砌块的方法具有防水效果好、强度高的优点.但是成本较单独掺活性火山质材料高,并且还存在石膏掺量低、制备工艺复杂等不足,若能在建筑石膏中只掺入活性火山灰质等材料,同时提高石膏掺量制备耐水石膏砌块,该制备技术的应用前景将更为广阔.

  14. Using Gypsum Hydration Water to Quantitatively Estimate the Intensity of the Terminal Classic Drought in the Maya Lowlands

    Gázquez, F.; Evans, N. P.; Bauska, T. K.; Hodell, D. A.


    Paleoclimate evidence suggests that drought coincided with the collapse of the lowland Classic Maya civilization between 800 and 1000 AD. However, attempts to quantitatively determine the magnitude of hydrologic change have met with mixed results. Several periods of gypsum deposition have been documented in Lake Chichancanab (Yucatan Peninsula, Mexico) sediment cores and interpreted as representing times of drought. Here we analyzed the triple oxygen (17O/16O, 18O/16O) and hydrogen (2H/1H) isotope ratios of the gypsum hydration water to obtain the δ18O, δD, 17O-excess, and d-excess of the lake water during the drought periods. By comparing these results to measurements made on the modern lake, rain and ground waters, we are able to better constrain the hydrological changes that occurred in the lake basin during the Terminal Classic Drought (TCD). During the TCD, the δ18O and δD of the lake water increased compared with modern values, whereas the 17O-excess, and d-excess decreased. The isotopic composition of lake water (δ17O, δ18O and δD, and derived d-excess and 17O-excess) is sensitive to changes in atmospheric relative humidity and temperature. We modeled the isotopic data and found the observed changes can be explained by a 10% reduction in relative humidity compared to modern conditions. This reduction in relative humidity was accompanied by a significant increase in evaporation over precipitation. Furthermore, we show that the driest period occurred during the early phase of the TCD (ca 770-870 AD) when the Classic Maya declined. Previous studies based on stalagmite δ18O records suggested that the greatest drought period occurred in the Postclassic Period (1020 and 1100 AD) and post-dated the collapse. Our findings from Lake Chichancanab suggest that the changes to the hydrological budget during the TCD were greater than those during the early Postclassic Period.

  15. The study of Influencing Maintenance Factors on Failures of Two gypsum Kilns by Failure Modes and Effects Analysis (FMEA

    Iraj Alimohammadi


    Full Text Available Developing technology and using equipment in Iranian industries caused that maintenance system would be more important to use. Using proper management techniques not only increase the performance of production system but also reduce the failures and costs. The aim of this study was to determine the quality of maintenance system and the effects of its components on failures of kilns in two gypsum production companies using Failure Modes and Effects Analysis (FMEA. Furthermore the costs of failures were studied. After the study of gypsum production steps in the factories, FMEA was conducted by the determination of analysis insight, information gathering, making list of kilns’ component and filling up the FMEA’s tables. The effects of failures on production, how to fail, failure rate, failure severity, and control measures were studied. The evaluation of maintenance system was studied by a check list including questions related to system components. The costs of failures were determined by refer in accounting notebooks and interview with the head of accounting department. It was found the total qualities of maintenance system in NO.1 was more than NO.2 but because of lower quality of NO.1’s kiln design, number of failures and their costs were more. In addition it was determined that repair costs in NO.2’s kiln were about one third of NO.1’s. The low severity failures caused the most costs in comparison to the moderate and low ones. The technical characteristics of kilns were appeared to be the most important factors in reducing of failures and costs.

  16. Evaluation and comparison of high-level microwave oven disinfection with chemical disinfection of dental gypsum casts.

    Meghashri, K; Kumar, Prasanna; Prasad, D Krishna; Hegde, Rakshit


    The aim of this study was to evaluate and compare microwave disinfection with chemical disinfection of dental gypsum casts. A total of 120 casts were prepared from a silicone mold using Type III dental stone. Of the 120 casts, 60 casts were contaminated with 1 ml suspension of Staphylococcus aureus and 60 casts were contaminated with 1 ml suspension of Pseudomonas aeruginosa. Then, the casts were disinfected with microwave irradiation and chemical disinfection using the microwave oven and 0.5% sodium hypochlorite. Bacteriologic procedures were performed; the cfu/ml for each cast was calculated as a weighted mean. The results were analyzed using Kruskal-Wallis test and Mann-Whitney test. The untreated casts showed Brain heart infusion broth counts of 106 log cfu/ml compared to irradiated and chemically disinfected casts, in which 105 log reduction of cfu/ml was seen. These results satisfied the requirements of current infection control guidelines for the dental laboratory. The results obtained for chemical disinfection were in equivalence with microwave disinfection. Within the limitation of this in vitro study, it was found that microwave disinfection of casts for 5 min at 900 W gives high-level disinfection that complies with the current infection control guidelines for the dental laboratory and microwave disinfection method is an effective and validated method as chemical disinfection. How to cite the article: Meghashri K, Kumar P, Prasad DK, Hegde R. Evaluation and comparison of high-level microwave oven disinfection with chemical disinfection of dental gypsum casts. J Int Oral Health 2014;6(3):56-60 .

  17. Preparation and application of gypsum block waterproofing agent%石膏砌块防水剂的制备与应用研究

    潘红; 李国忠


    选用自由基溶液聚合的方式合成氟硅改性丙烯酸酯树脂,加入固化剂制得双组分石膏砌块防水剂。研究了有机硅功能单体、有机氟功能单体对防水剂憎水性能的改性效果,探讨了功能单体的作用机理。分别选用外涂和内掺的方法将制得的防水剂用于石膏砌块试样中,研究其对石膏砌块试样的抗折、抗压强度、吸水率以及软化系数的影响。试验结果表明:外涂防水剂的方法可明显降低石膏砌块试样浸水2h的吸水率;内掺防水剂的方法对石膏砌块试样的浸水2h、24h吸水率均有了一定程度的改善,其24h软化系数为0.71,达到防潮石膏砌块的标准要求。%A kind of gypsum block waterproofing agent is introduced, which is made of fluorine silicon modified acrylate resin and hardener. The modification effect of organic silicon and organic fluorine monomers on the water resistant of the waterproofing agent is researched. The waterproofing agent is respectively applied on gypsum block samples by coating or doping method. Effects of the agent on flexural strength, compressive strength and water absorption of gypsum block samples are studied. The experimental results show that the water absorption of gypsum block sample coated with waterproofing agent in water for 2h is significantly reduced; and the water absorption of gypsum block sample added waterproofing agent in water for 2h and 24h is also reduced, which softening coefficient reaches 0.71 for 24h, and fulfills the standard requirement of moisture resistant gypsum blocks.

  18. Water-Extractable Carbon Pools and Microbial Biomass Carbon in Sodic Water-Irrigated Soils Amended with Gypsum and Organic Manures



    Microbial biomass carbon (MBC),a small fraction of soil organic matter,has a rapid turnover rate and is a reservoir of labile nutrients.The water-extractable carbon pools provide a fairly good estimate of labile C present in soil and can be easily quantified.Changes in soil MBC and water-extractable organic carbon pools were studied in a 14-year long-term experiment in plots of rice-wheat rotation irrigated with canal water (CW),sodic water (SW,10-12.5 mmolc L-1 residual sodium carbonate),and SW amended with gypsum with or without application of organic amendments including farmyard manure (FYM),green manure (GM),and wheat straw (WS).Irrigation with SW increased soil exchangeable sodium percentage by more than 13 times compared to irrigation with CW.Sodic water irrigation significantly decreased hot water-extractable organic carbon (HWOC) from 330 to 286 mg kg-1 soil and cold water-extractable organic carbon (CWOC) from 53 to 22 mg kg-1 soil in the top 0-7.5 cm soil layer.In the lower soil layer (7.5-15 cm),reduction in HWOC was not significant.Application of gypsum alone resulted in a decrease in HWOC in the SW plots,whereas an increase was recorded in the SW plots with application of both gypsum and organic amendments in both the soil layers.Nevertheless,application of gypsum and organic amendments increased the mean CWOC as compared with application of gypsum alone.CWOC was significantly correlated with MBC but did not truly reflect the changes in MBC in the treatments with gypsum and organic amendments applied.For the treatments without organic amendments,HWOC was negatively correlated with MBC (r =-0.57*)in the 0-7.5 cm soil layer,whereas for the treatments with organic amendments,both were positively correlated.Irrigation with SW significantly reduced the rice yield by 3 t ha-1 and the yield of rice and wheat by 5 t ha-1 as compared to irrigation with canal water.Application of amendments significantly increased rice and wheat yields.Both the rice yield and

  19. The next chapter in experimental petrology: Metamorphic dehydration of polycrystalline gypsum captured in 3D microtomographic time series datasets

    Bedford, John; Fusseis, Florian; Leclere, Henry; Wheeler, John; Faulkner, Dan


    Nucleation and growth of new minerals in response to disequilibrium is the most fundamental metamorphic process. However, our current kinetic models of metamorphic reactions are largely based on inference from fossil mineral assemblages, rather than from direct observation. The experimental investigation of metamorphism has also been limited, typically to concealed vessels that restrict the possibility of direct microstructural monitoring. Here we present one of the first time series datasets that captures a metamorphic reaction, dehydration of polycrystalline gypsum to form hemihydrate, in a series of three dimensional x-ray microtomographic datasets. We achieved this by installing an x-ray transparent hydrothermal cell (Fusseis et al., 2014, J. Synchrotron Rad. 21, 251-253) in the microtomography beamline 2BM at the Advanced Photon Source (USA). In the cell, we heated a millimetre-sized sample of Volterra Alabaster to 388 K while applying an effective pressure of 5 MPa. Using hard x-rays that penetrate the pressure vessel, we imaged the specimen 40 times while it reacted for approximately 10 hours. Each microtomographic dataset was acquired in 300 seconds without interrupting the reaction. Our absorption microtomographic data have a voxel size of 1.3 μm, which suffices to analyse the reaction progress in 4D. Gypsum can clearly be distinguished from hemihydrate and pores, which form due to the large negative solid volume change. On the resolved scale, the first hemihydrate needles appear after about 2 hours. Our data allow tracking of individual needles throughout the entire experiment. We quantified their growth rates by measuring their circumference. While individual grains grow at different rates, they all start slowly during the initial nucleation stage, then accelerate and grow steadily between about 200 and 400 minutes before reaction rate decelerates again. Hemihydrate needles are surrounded by porous haloes, which grow with the needles, link up and

  20. Characterization of mudejar mortars from St. Gil Abbot church (Zaragoza, Spain: Investigation of the manufacturing technology of ancient gypsum mortars

    Igea, J.


    Full Text Available This work has been focused on the investigation of the technological procedure of Mudejar mortars applied to the characterization of a group of unaltered samples from an example church of Mudejar architecture of Aragon. The research was carried out using multi-analytical techniques including petrographic study, chemistry and mineralogical analysis. All mortars present a homogeneous composition. The binder is made up of a mixture of gypsum and a very low proportion of lime, while the main components of the aggregate are gypsum and carbonate rock fragments, both in a different thermal state of decomposition. The results have proved that both, binder and aggregates display the same composition in these mortars. These aggregates are the by-product of a grinding process of the previously burnt raw materials which have had a positive influence on the properties of the mortars in improving their quality.

    Este trabajo se ha centrado en la investigación de la tecnología de fabricación de morteros mudéjares mediante la caracterización de un conjunto de muestras inalteradas procedentes de una iglesia representativa de la arquitectura Mudéjar aragonesa. La investigación se llevó a cabo mediante el uso combinado de técnicas analíticas incluyendo el estudio petrográfico y el análisis químico y mineralógico. Todos los morteros presentan una composición constante formada por una mezcla de yeso y cal, en muy baja proporción, como ligante, mientras que el árido está formado por fragmentos de rocas yesíferas y carbonatadas en distinto estado de descomposición térmica. Los resultados confirman que en la fabricación de los morteros, ligante y áridos presentan la misma composición, siendo éstos últimos el subproducto de la misma materia prima calcinada, incorporados para elaborar el mortero, tras un proceso de molienda. Esta característica ha influido positivamente en las propiedades de los morteros, mejorando su calidad.

  1. Preliminary Examination of the System Fly Ash-Bottom Ash-Flue Gas Desulphurization Gypsum-Portland Cement-Water for Road Construction

    R. Tokalic


    Full Text Available This paper describes an investigation into the use of three power plant wastes: fly ash, flue gas desulphurization gypsum, and bottom ash for subbase layers in road construction. Two kinds of mixtures of these wastes with Portland cement and water were made: first with fly ash consisting of coarser particles (<1.651 mm and second with fly ash consisting of smaller particles (<0.42 mm. The mass ratio of fly ash-Portland cement-flue gas desulphurization gypsum-bottom ash was the same (3 : 1 : 1 : 5 in both mixtures. For both mixtures, the compressive strength, the mineralogical composition, and the leaching characteristics were determined at different times, 7 and 28 days, after preparation. The obtained results showed that both mixtures could find a potential use for subbase layers in road construction.

  2. Manufacture of Durable Stucco Gypsum in Outdoor Plastering Engineering%耐久型室外粉刷石膏的性能及微观结构

    余红发; 丁向群


    研究白水泥等作激发剂的难溶性无水石膏的性能,并制备出用于室外条件下的耐久型粉刷石膏.用XRD和SEM-EDAX分析了耐久型粉刷石膏外墙饰面使用18年后的相组成和显微结构.%The properties of anhydrite [1 with white protland cement as accelerating agent are studied, and the durable stucco gypsum in outdoor condition are prepared successfully. The phase composition and microstructure of the durable stucco gypsum external veneer after 18 years' exposure are analyzed by XRD and SEM-EDAX.

  3. 脱硫石膏砌块力学性能的研究%Study on Mechanical Properties of Desulfurization Gypsum Block

    何廷树; 孟晓林; 史琛


    Industrial waste gypsum, lfy ash mixed with small amount of cement and expanded polystyrene particles are used as mixed material to reduce weight and ensure the strength through experimental study on the mechanical properties and the change of apparent density of desulfurization gypsum block. The experimental results show that the optimal ratio were 0.42% lignosulphonate calcium water reducers, 0.12% citric acid retarder, 0.06% lignocellulose, 15% cement, 10% lfy ash, 75% desulphurization gypsum, 25% polystyrene particles. Light desulfurization gypsum block with density of 964kg/m3 and 10.1MPa of 28 d compressive strength can be obtained.%为达到脱硫石膏砌块减重且保证强度的目的,利用工业废料脱硫石膏、粉煤灰,掺加少量水泥、膨胀聚苯颗粒作为混合材料,研究脱硫石膏实心砌块的力学性能及表观密度的变化。结果表明,制备脱硫石膏砌块最优配比为:木钙减水剂0.42%、柠檬酸缓凝剂0.12%、木质纤维素0.06%、水泥15%、粉煤灰10%、脱硫石膏75%、聚苯颗粒25%,此条件下可获得密度为964 kg/m3,28 d抗压强度达10.1 MPa的轻质脱硫石膏砌块。

  4. 氟石膏泡沫混凝土砌块的性能研究%Study on properties of fluorine gypsum foam concrete block

    谢建海; 赵党会; 向仁科


      以氟石膏、粉煤灰和水泥为基材,加入自制添加剂改性,外掺少量促凝剂、CaO和减水剂,再掺加适量发泡剂制备出不同密度等级的氟石膏泡沫混凝土砌块。研究了不同外加剂掺量对胶凝材料初终凝时间和力学性能的影响,测试了氟石膏泡沫混凝土的导热系数。实验表明:氟石膏泡沫混凝土砌块强度高、导热系数低,产品综合性能优良,是实现工业副产品氟石膏资源化利用途径之一。%  The fluorine gypsum foam concrete block is made of the fluorine gypsum, fly ash and cement as base material, mixed with modifier,small amount of coagulant, CaO, water reducer and proper quantity foaming agent and so on. The influence of different admixture on the initial-final setting times and mechanical performance of gelling material is researched, and the thermal conductivity of fluorine gypsum foam concrete is measured. Experiments show that the fluorine gypsum foam concrete blocks have high strength, low thermal conductivity, and excellent comprehensive properties.

  5. Study on Comprehensive Utilization of Gypsum as the By-product of Copper Smelting%铜冶炼副产品石膏的综合利用研究



    阐述了国内外工业副产品石膏的处理现状,研究了碳对石膏高温分解反应的影响.试验结果表明,碳的存在可以大幅降低石膏的分解温度,闪速炉反应塔的温度可以满足碳存在时的石膏分解温度要求,为工业石膏、活性焦这两种固体废弃物的处理及利用提供了途径,可实现变废为宝.%In this paper, the handling situation of industrial by-product gypsum at home and abroad was laborated, and the influence of carbon on gypsum pyrolysis reaction was studied. The experimental results show that the presence of carbon could greatly reduce the decomposition temperature of gypsum. The temperature of the reaction tower in flash furnace could satisfy the temperature requirement of gypsum decomposition when carbon was present. It provided the basis for the treatment and utilization of two kinds of industrial solid waste gypsum, activated coke and industrial gypsum in this study, and it implemented turning waste into treasure.

  6. Cytotoxic and genotoxic effects of water and sediment samples from gypsum mining area in channel catfish ovary (CCO) cells.

    Ternjej, Ivančica; Gaurina Srček, Višnja; Mihaljević, Zlatko; Kopjar, Nevenka


    Man-made activities such as mining generate certain amounts of metal contaminated wastes which can reach aquatic environment and cause the serious effects on different organisms and ecosystem. Chemical analysis of the environmental samples is the most direct approach to reveal their pollution status but it cannot always provide information on biological effects to different organisms, including fish. This study was aimed to investigate the in vitro cytotoxicity and genotoxicity of water and sediment samples from gypsum mining area using the channel catfish ovary (CCO) cell line. Results obtained by the WST-1 assay and alkaline comet assay revealed that exposure of CCO cells to the same concentrations of contaminated water and sediment samples caused significant decrease in cell viability and increased DNA damages. Chemical analysis of water and sediment samples showed that increased concentrations of strontium, aluminum and iron were mainly responsible for the observed cytotoxic and genotoxic effects in CCO cells. The study suggested that fish CCO cells could be useful biological test-system for water and sediment cytotoxicity and genotoxicity assessments. © 2013 Elsevier Inc. All rights reserved.

  7. Adsorption of mercury in coal-fired power plants gypsum slurry on TiO2/chitosan composite material

    Gao, P.; Gao, B. B.; Gao, J. Q.; Zhang, K.; Chen, Y. J.; Yang, Y. P.; Chen, H. W.


    In this study, a simple method was used to prepare a chitosan adsorbent to mix with KI and TiO2. Gravimetric analysis (TG), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the samples before and after adsorption of Hg2+. A mercury adsorption experiment was also conducted in the gypsum slurry. The results show that using hydrobromic acid as a solvent of adsorbent resulted in a better adsorption effect than using acetic acid alone. Also, the sample (CS-KI/TiO2-HBr) had a maximum mercury adsorption capacity when the pH=5 and the t=50°C. The characterization experiments showed that the thermal stability of composite materials declined and the TiO2 uniformly dispersed in the surface of the samples with a lamellar structure, generating a lot of cracks and recesses that increased the reactive sites. Furthermore, when the TiO2 reacted with CS, it resulted in Ti-C, Ti-O and Ti-N bonds. The Br- can prevent the growth of TiO2 crystal grains and strengthen the ability of I- to remove mercury. The adsorption isotherm and kinetic results indicated that the adsorption behaviour of CS-KI/TiO2-HBr as it removes Hg2+ is an inhomogeneous multilayer adsorption process. The surface adsorption and intraparticle diffusion effects are both important in the Hg2+ adsorption process.

  8. Fabrication of calcite blocks from gypsum blocks by compositional transformation based on dissolution-precipitation reactions in sodium carbonate solution.

    Ishikawa, Kunio; Kawachi, Giichiro; Tsuru, Kanji; Yoshimoto, Ayami


    Calcium carbonate (CaCO3) has been used as a bone substitute, and is a precursor for carbonate apatite, which is also a promising bone substitute. However, limited studies have been reported on the fabrication of artificial calcite blocks. In the present study, cylindrical calcite blocks (ϕ6×3mm) were fabricated by compositional transformation based on dissolution-precipitation reactions using different calcium sulfate blocks as a precursor. In the dissolution-precipitation reactions, both CaSO4·2H2O and CaSO4 transformed into calcite, a polymorph of CaCO3, while maintaining their macroscopic structure when immersed in 1mol/L Na2CO3 solution at 80°C for 1week. The diametral tensile strengths of the calcite blocks formed using CaSO4·2H2O and CaSO4 were 1.0±0.3 and 2.3±0.7MPa, respectively. The fabrication of calcite blocks using CaSO4·2H2O and CaSO4 proposed in this investigation may be a useful method to produce calcite blocks because of the self-setting ability and high temperature stability of gypsum precursors.

  9. Arsenic leaching and speciation in C&D debris landfills and the relationship with gypsum drywall content.

    Zhang, Jianye; Kim, Hwidong; Dubey, Brajesh; Townsend, Timothy


    The effects of sulfide levels on arsenic leaching and speciation were investigated using leachate generated from laboratory-scale construction and demolition (C&D) debris landfills, which were simulated lysimeters containing various percentages of gypsum drywall. The drywall percentages in lysimeters were 0, 1, 6, and 12.4wt% (weight percent) respectively. With the exception of a control lysimeter that contained 12.4wt% of drywall, each lysimeter contained chromated copper arsenate (CCA) treated wood, which accounts for 10wt% of the C&D waste. During the period of study, lysimeters were mostly under anaerobic conditions. Leachate analysis results showed that sulfide levels increased as the percentage of drywall increased in landfills, but arsenic concentrations in leachate were not linearly correlated with sulfide levels. Instead, the arsenic concentrations decreased as sulfide increased up to approximately 1000μg/L, but had an increase with further increase in sulfide levels, forming a V-shape on the arsenic vs. sulfide plot. The analysis of arsenic speciation in leachate showed different species distribution as sulfide levels changed; the fraction of arsenite (As(III)) increased as the sulfide level increased, and thioarsenate anions (As(V)) were detected when the sulfide level further increased (>10(4)μg/L). The formation of insoluble arsenic sulfide minerals at a lower range of sulfide and soluble thioarsenic anionic species at a higher range of sulfide likely contributed to the decreasing and increasing trend of arsenic leaching. Copyright © 2016. Published by Elsevier Ltd.

  10. The effect of strong salinity and temperature gradients on transport processes and the formation of bathyal authigenic gypsum at a marine mud volcano

    Haffert, L.; Haeckel, M.


    A thermodynamic activity model (Pitzer approach) applicable to extreme environmental pTS-conditions (up to 1000 bar, 200 ° C and 6 M NaCl) coupled to an extensive mineral database has been developed. The advantage of this code over existing ones, such as Phreeqc, Wateq, Minteq, is the additional integration of a comprehensive pressure correction, as well as the flexibility on the choice of input datasets, allowing fine-tuning of the model according the relevant pTS range. An example of the successful application of the model is the interpretation of near-surface pore water profiles from the Mercator mud volcano in the Gulf of Cadiz. These profiles are intriguing for two reasons. First, they are characterised by a strong salinity gradient in the upper 1-2 mbsf created by the mixing of upward advecting hypersaline (halite and gypsum saturated, S=360) mud volcano fluids and seawater (S=35) and, second, the pore water profiles encompass various types of authigenic gypsum (CaSO4·2H2O) and anhydrite (CaSO4) crystals, which usually form only in evaporitic environments. It was found that while high Ca and SO4 concentrations from dissolution of an underlying diapir provide gypsum saturated fluids, the occurrence of supersaturation and thus authigenic gypsum (or anhydrite) precipitation is only possible through the reduction of temperature. In addition to the strong temperature control, the salinity has an important impact on the resultant composition of the precipitating CaSO4 minerals. Increasing salinity significantly lowers the activity of water, thereby raising the gypsum-anhydrite transition zone from >1 km to about 500 m sediment depth at the MMV and during heat pulses (> 30 ° C) even to within a few metres below the seafloor. Another effect of the strong salinity gradient is its influence on the diffusive transport of solutes. When comparing the activity and concentration profiles of dissolved species at the Mercator mud volcano, it becomes obvious that here the

  11. Manufacturing of mortars and concretes non-traditionals, by Portland cement, metakaoline and gypsum (15.05%

    Talero, R.


    Full Text Available In a thorough previous research (1, it appeared that creation, evolution and development of the values of compressive mechanical strength (CS and flexural strength (FS, measured in specimens 1x1x6cm of mortar type ASTM C 452-68 (2, manufactured by ordinary Portland cement P-1 (14.11% C3A or PY-6 (0.00% C3A, metakaolin and gypsum (CaSO4∙2H2O -or ternary cements, CT-, were similar to the ones commonly developed in mortars and concretes of OPC. This paper sets up the experimental results obtained from non-traditional mortars and concretes prepared with such ternary cements -TC-, being the portland cement/metakaolin mass ratio, as follows: 80/20, 70/30 and 60/40. Finally, the behaviour of these cements against gypsum attack, has been also determined, using the following parameters: increase in length (ΔL%, compressive, CS, and flexural, FS, strengths, and ultrasound energy, UE. Experimental results obtained from these non-traditional mortars and concretes, show an increase in length (ΔL, in CS and FS, and in UE values, when there is addition of metakaolin.

    En una exhaustiva investigación anterior (1, se pudo comprobar que la creación, evolución y desarrollo de los valores de resistencias mecánicas a compresión, RMC, y flexotracción, RMF, proporcionados por probetas de 1x1x6 cm, de mortero 1:2,75, selenitoso tipo ASTM C 452-68 (2 -que habían sido preparadas con arena de Ottawa, cemento portland, P-1 (14,11% C3A o PY- 6 (0,00% C3A, metacaolín y yeso (CaSO4∙2H2O-, fue semejante a la que, comúnmente, desarrollan los morteros y hormigones tradicionales de cemento portland. En el presente trabajo se exponen los resultados experimentales obtenidos de morteros y hormigones no tradicionales, preparados con dichos cementos ternarios, CT, siendo las proporciones porcentuales en masa ensayadas, cemento portland/metacaolín, las siguientes: 80/20, 70

  12. Comparative evaluation of feldespatic crowns fitness made from additional silicon impression and gypsum cast by CAD/CAM

    Faramarz Zakavi


    Full Text Available Background and Aims: Marginal fit is one of the key factors in the success of fixed restoration. The aim of this study was to evaluate the fitness of feldespatic crowns made from additional silicon impression and gypsum cast by CAD/CAM.   Materials and Methods: 10 intact extracted upper premolar teeth were used for this experimental study. After preparation of the mounted teeth with radial shoulder finish line, 2 Vita Mark II feldespatic CAD/CAM machined crowns were fabricated for each tooth (one from scanning the additional silicone impression of the prepared tooth and the other one from the plaster model. Marginal gap of each crown was measured using SEM in two points on the mesial and 2 points on the buccal surface. Data were analyzed using Paired t-test with SPSS version 17 software (P<0.05.   Results: The mean of marginal gaps in crowns fabricated from additional silicone and model plaster were (155.13±37.11 and (130.18±12.35, respectively. However, no significant difference emerged between marginal gaps of the two methods (P=0.055. Also, the mean of marginal gaps in crowns fabricated from additional silicone and model plaster was higher in mesial (157.82±44.41 compared to buccal (127.50±24.26 region (P=0.003.   Conclusion: Marginal fit was not significantly differen ce between crown s made of the plaster casts and silicone molds and both methods showed the same results .

  13. Microbial diversity in the deep-subsurface hydrothermal aquifer feeding the giant gypsum crystal-bearing Naica Mine, Mexico.

    Ragon, Marie; Van Driessche, Alexander E S; García-Ruíz, Juan M; Moreira, David; López-García, Purificación


    The Naica Mine in northern Mexico is famous for its giant gypsum crystals, which may reach up to 11 m long and contain fluid inclusions that might have captured microorganisms during their formation. These crystals formed under particularly stable geochemical conditions in cavities filled by low salinity hydrothermal water at 54-58°C. We have explored the microbial diversity associated to these deep, saline hydrothermal waters collected in the deepest (ca. 700-760 m) mineshafts by amplifying, cloning and sequencing small-subunit ribosomal RNA genes using primers specific for archaea, bacteria, and eukaryotes. Eukaryotes were not detectable in the samples and the prokaryotic diversity identified was very low. Two archaeal operational taxonomic units (OTUs) were detected in one sample. They clustered with, respectively, basal Thaumarchaeota lineages and with a large clade of environmental sequences branching at the base of the Thermoplasmatales within the Euryarchaeota. Bacterial sequences belonged to the Candidate Division OP3, Firmicutes and the Alpha- and Beta-proteobacteria. Most of the lineages detected appear autochthonous to the Naica system, since they had as closest representatives environmental sequences retrieved from deep sediments or the deep subsurface. In addition, the high GC content of 16S rRNA gene sequences belonging to the archaea and to some OP3 OTUs suggests that at least these lineages are thermophilic. Attempts to amplify diagnostic functional genes for methanogenesis (mcrA) and sulfate reduction (dsrAB) were unsuccessful, suggesting that those activities, if present, are not important in the aquifer. By contrast, genes encoding archaeal ammonium monooxygenase (AamoA) were amplified, suggesting that Naica Thaumarchaeota are involved in nitrification. These organisms are likely thermophilic chemolithoautotrophs adapted to thrive in an extremely energy-limited environment.

  14. Microbial diversity in the deep-subsurface hydrothermal aquifer feeding the giant gypsum crystal-bearing Naica mine, Mexico

    Marie eRagon


    Full Text Available The Naica mine in Northern Mexico is famous for its giant gypsum crystals, which may reach up to 11 m long and contain fluid inclusions that might have captured microorganisms during their formation. These crystals formed under particularly stable geochemical conditions in cavities filled by low salinity hydrothermal water at 54-58°C. We have explored the microbial diversity associated to these deep, saline hydrothermal waters collected in the deepest (ca. 700-760 m mineshafts by amplifying, cloning and sequencing small-subunit ribosomal RNA genes using primers specific for archaea, bacteria and eukaryotes. Eukaryotes were not detectable in the samples and the prokaryotic diversity identified was very low. Two archaeal operational taxonomic units (OTUs were detected in one sample. They clustered with, respectively, basal Thaumarchaeota lineages and with a large clade of environmental sequences branching at the base of the Thermoplasmatales within the Euryarchaeota. Bacterial sequences belonged to the Candidate Division OP3, Firmicutes and the Alpha- and Beta-Proteobacteria. Most of the lineages detected appear autochthonous to the Naica system, since they had as closest representatives environmental sequences retrieved from deep sediments or the deep subsurface. In addition, the high GC content of 16S rRNA gene sequences belonging to the archaea and to some OP3 OTUs suggests that at least these lineages are thermophilic. Attempts to amplify diagnostic functional genes for methanogenesis (mcrA and sulfate reduction (dsrAB were unsuccessful, suggesting that those activities, if present, are not important in the aquifer. By contrast, genes encoding archaeal ammonium monooxygenase (AamoA were amplified, suggesting that Naica Thaumarchaeota are involved in nitrification. These organisms are likely thermophilic chemolithoautotrophs adapted to thrive in an extremely energy-limited environment.

  15. Calcium Sulfate Hemihydrate Whiskers Obtained from Flue Gas Desulfurization Gypsum and Used for the Adsorption Removal of Lead

    Xiaoshu Wang


    Full Text Available Abstract: As a recycled material, flue gas desulfurization gypsum has been used to prepare calcium sulfate hemihydrate whisker (CSHW through hydrothermal synthesis for several decades. However, the subsequent utilization of this resultant material has not yet received considerable attention. In the present research, CSHW was successfully synthesized at a certain region, and was used for the adsorption of lead ions from aqueous solutions, thereby broadening the research field for the practical application of CSHW. Its adsorption capacity was significantly influenced by various parameters, particularly, the pH level and initial lead concentration. The pH value highly affected the hydrolysis degree of lead ions and dominated the adsorption of lead. The equilibrium isotherms under two different temperatures were simulated using Langmuir, Freundlich, and Temkin models. Both Langmuir and Temkin models showed a good fit to the data. Combined with the well-fitted pseudo-second-order model, the adsorption mechanism was thought to be a chemisorption process that was enforced by the ion exchange reaction. In addition, the specific crystal structure of CSHW revealed that ion exchange reaction occurred on the (010 and (100 facets due to their preferential growth and negatively charged property. The residual solid phase after adsorption was collected and detected using X-ray diffraction and scanning electron microscopy with energy dispersive X-ray spectroscopy. Results revealed that PbSO4 was formed on the surface of CSHW. The alkaline condition introduced the tribasic lead sulfate, and thus reduced the stability of the adsorption system.

  16. Microbial characterization of microbial ecosystems associated to evaporites domes of gypsum in Salar de Llamara in Atacama desert.

    Rasuk, Maria Cecilia; Kurth, Daniel; Flores, Maria Regina; Contreras, Manuel; Novoa, Fernando; Poire, Daniel; Farias, Maria Eugenia


    The Central Andes in northern Chile contains a large number of closed basins whose central depression is occupied by saline lakes and salt crusts (salars). One of these basins is Salar de Llamara (850 m a.s.l.), where large domed structures of seemingly evaporitic origin forming domes can be found. In this work, we performed a detailed microbial characterization of these domes. Mineralogical studies revealed gypsum (CaSO(4)) as a major component. Microbial communities associated to these structures were analysed by 454 16S rDNA amplicon sequencing and compared between winter and summer seasons. Bacteroidetes Proteobacteria and Planctomycetes remained as the main phylogenetic groups, an increased diversity was found in winter. Comparison of the upper air-exposed part and the lower water-submerged part of the domes in both seasons showed little variation in the upper zone, showing a predominance of Chromatiales (Gammaproteobacteria), Rhodospirillales (Alphaproteobacteria), and Sphingobacteriales (Bacteroidetes). However, the submerged part showed marked differences between seasons, being dominated by Proteobacteria (Alpha and Gamma) and Verrucomicrobia in summer, but with more diverse phyla found in winter. Even though not abundant by sequence, Cyanobacteria were visually identified by scanning electron microscopy (SEM), which also revealed the presence of diatoms. Photosynthetic pigments were detected by high-performance liquid chromatography, being more diverse on the upper photosynthetic layer. Finally, the system was compared with other endoevaporite, mats microbialite and Stromatolites microbial ecosystems, showing higher similitude with evaporitic ecosystems from Atacama and Guerrero Negro. This environment is of special interest for extremophile studies because microbial life develops associated to minerals in the driest desert all over the world. Nevertheless, it is endangered by mining activity associated to copper and lithium extraction; thus, its

  17. Evaluation of surface detail reproduction, dimensional stability and gypsum compatibility of monophase polyvinyl-siloxane and polyether elastomeric impression materials under dry and moist conditions.

    Vadapalli, Sriharsha Babu; Atluri, Kaleswararao; Putcha, Madhu Sudhan; Kondreddi, Sirisha; Kumar, N Suman; Tadi, Durga Prasad


    This in vitro study was designed to compare polyvinyl-siloxane (PVS) monophase and polyether (PE) monophase materials under dry and moist conditions for properties such as surface detail reproduction, dimensional stability, and gypsum compatibility. Surface detail reproduction was evaluated using two criteria. Dimensional stability was evaluated according to American Dental Association (ADA) specification no. 19. Gypsum compatibility was assessed by two criteria. All the samples were evaluated, and the data obtained were analyzed by a two-way analysis of variance (ANOVA) and Pearson's Chi-square tests. When surface detail reproduction was evaluated with modification of ADA specification no. 19, both the groups under the two conditions showed no significant difference statistically. When evaluated macroscopically both the groups showed statistically significant difference. Results for dimensional stability showed that the deviation from standard was significant among the two groups, where Aquasil group showed significantly more deviation compared to Impregum group (P impregum and aquasil performed better in dry condition than in moist; impregum performed better than aquasil in both the conditions. When tested for surface detail reproduction according to ADA specification, under dry and moist conditions both of them performed almost equally. When tested according to macroscopic evaluation, impregum and aquasil performed significantly better in dry condition compared to moist condition. In dry condition, both the materials performed almost equally. In moist condition, aquasil performed significantly better than impregum. Regarding gypsum compatibility according to ADA specification, in dry condition both the materials performed almost equally, and in moist condition aquasil performed better than impregum. When tested by macroscopic evaluation, impregum performed better than aquasil in both the conditions.

  18. Study on the preparation of fibers reinforced gypsum-based foamed composite materials%纤维增强石膏发泡材料的研制

    李淋淋; 李国忠


    以脱硫建筑石膏、粉煤灰、发泡剂为原材料制备发泡脱硫石膏保温材料。研究不同发泡剂掺量对其密度、力学性能和导热系数的影响,结果表明,发泡剂掺量为5%时,导热系数最小,为0.052 W/(m·K),此时脱硫石膏发泡材料的密度为225 kg/m3。利用玻璃纤维作为增强材料,研究了玻璃纤维的掺加对材料强度的影响。结果表明,当玻璃纤维掺量为1.5%时,试样的抗折强度提高了41.67%。%The paper researches a kind of insulation foamed desulfurization gypsum material prepared by the desulfurization gypsum, foaming agent and fly ash from the aspects of the influence of different content of foaming agent on its density, mechanical properties and thermal conductivity. The result shows that when the content of foaming agent is 5%, the thermal conductivity is minimum heat conduction coefficient of 0.052 W/(m·K), and the density of foamed desulfurization gypsum is 225 kg/m3 . And also researches the effect of additive content of glass fiber as reinforcing material on strength of the material. The result shows that when the content of glass fiber is 1.5%, the transverse strength of the sample increases 41.67%.

  19. Organic geochemistry of endoevaporitic environments: Microbial diversity and lipid biomarkers from gypsum deposits at the E.S.S.A Salt Works, Guerrero Negro, Baja, Mexico

    Vogel, M. B.; Des Marais, D. J.; Jahnke, L. L.; Turk, K. A.; Kubo, M. D.


    We report lipid biomarker distributions and microbial diversity of endoevaporitic microbial communities from the gypsum crystallizer pond (Pond #9; ~170 % salinity) at the Exportadora de Sal, (ESSA) salt works in Guerrero Negro, Baja California Sur, Mexico. According to phylogenetic analysis using 16S rRNA sequences, gypsum crusts from this system host stratified communities of unicellular cyanobacteria (orange Euhalothece), filamentous cyanobacteria (green Oscillatoria), purple sulfur bacteria (Chromatium), and other halophilic microorganisms. Lipids collected from spatially discrete horizons of the crust indicate a shift in C16, C18 and C19 fatty acids from lower concentrations in the upper aerobic layers to higher concentrations in the deeper anaerobic zones of the crust. Compound specific isotopic analyses (CSIA) of fatty acids differentiate the more abundant C16, C18 and C19 homologues as isotopically lighter (~ -20% to -25% δ13C VPDB) from C15, C17 and C20 homologues which are isotopically heavier (~ -14% to -19% δ13C VPDB) and occur in lower abundance. CSIA of multiple compound classes reveals that gypsum domain lipids have significantly lighter δ13C values than those of lipids from the laminated benthic microbial mats living at lower salinities (i.e. ~100% to 115% salinity) in the ESSA system. This isotopic effect is consistent with intensive internal nutrient cycling within the crust. Squalane/squalene were detected in extracts from the gypsum crust indicating the presence of archaea. Diploptene is the most abundant triterpenoid of the C28 C32 hopanoids. Branched alkanes with quaternary substituted carbons (BAQCs) were also detected. These compounds have been linked with sulfur oxidizing microbial activity, which is known to be a major respiratory process in the crust's internal O2 budget (Sørensen et al., 2004). Abundant organosulfur compounds (OSC) and thiacycloalkanes in extracts indicate a vigorous internal sulfur cycle that influences both

  20. Arsenic speciation in synthetic gypsum (CaSO4·2H2O): A synchrotron XAS, single-crystal EPR, and pulsed ENDOR study

    Lin, Jinru; Chen, Ning; Nilges, Mark J.; Pan, Yuanming


    Gypsum (CaSO4·2H2O) is a major by-product of mining and milling processes of borate, phosphate and uranium deposits worldwide and, therefore, potentially plays an important role in the stability and bioavailability of heavy metalloids, including As, in tailings and surrounding areas. Gypsum containing 1900 and 185 ppm As, synthesized with Na2HAsO4·7H2O and NaAsO2 in the starting materials, respectively, have been investigated by synchrotron X-ray absorption spectroscopy (XAS), single-crystal electron paramagnetic resonance spectroscopy (EPR), and pulsed electron nuclear double resonance spectroscopy (ENDOR). Quantitative analyses of As K edge XANES and EXAFS spectra show that arsenic occurs in both +3 and +5 oxidation states and the As3+/As5+ value varies from 0.35 to 0.79. Single-crystal EPR spectra of gamma-ray-irradiated gypsum reveal two types of arsenic-associated oxyradicals: [AsO3]2- and an [AsO2]2-. The [AsO3]2- center is characterized by principal 75As hyperfine coupling constants of A1 = 1952.0(2) MHz, A2 = 1492.6(2) MHz and A3 = 1488.7(2) MHz, with the unique A axis along the S-O1 bond direction, and contains complex 1H superhyperfine structures that have been determined by pulsed ENDOR. These results suggest that the [AsO3]2- center formed from electron trapping on the central As5+ ion of a substitutional (AsO4)3- group after removal of an O1 atom. The [AsO2]2- center is characterized by its unique A(75As) axis approximately perpendicular to the O1-S-O2 plane and the A2 axis along the S-O2 bond direction, consistent with electron trapping on the central As3+ ion of a substitutional (AsO3)3- group after removal of an O2 atom. These results confirm lattice-bound As5+ and As3+ in gypsum and point to potential application of this mineral for immobilization and removal of arsenic pollution.

  1. Human-induced hydrological changes and sinkholes in the gypsum karst of Lesina Marina area (Foggia Province, Italy)

    Fidelibus, M. D.; Gutierrez, F.; Spilotro, G.


    The Lesina Lagoon is located in the East-West-trending northern cost of Gargano (southern Italy). The lagoon is fed by springs draining the northern side of the Gargano Mesozoic carbonate aquifer and is connected with the sea by three channels, including the 2.2 km long Acquarotta Canal with a N-S orientation. The sea-side mouth of this canal was frequently clogged by sand accumulation. In 1927, the path of the northern section of this canal was changed to improve the water exchange between the lagoon and the Adriatic Sea for environmental and fish-farming purposes. The new portion of the canal, 8.5 m wide and 1.5 m deep, was excavated in evaporite bedrock and in a small outcrop of igneous rocks situated in the coast that inhibits sand accumulation. The Acquarotta Canal conveys water in both directions depending on the relative water levels of the lagoon and the sea. Initially the reach of the canal dug in gypsum was lined with concrete, which was replaced in 1993 by gabions for scenery improvement. The northern reach of the canal is dug in Upper Triassic gypsiferous sediments of the Burano Anhydrite Formation. The evaporite bedrock is mantled by unconsolidated deposits a few meters thick, largely made up of loose sand. The exposures found in the banks of the canal and in some sinkholes reveal that the gypsum has a high density of dissolutional conduits and cavities. Locally, it also shows open fractures and brecciated structure (crackle, mosaic and chaotic packbreccias) caused by dissolution-induced collapse processes. These voids, either of solutional or mechanical origin, are partially filled with detrital sediments derived from the mantling deposits. These features seem to correspond to a paleokarst, probably developed at several depths controlled by different and much lower sea level stands during the Quaternary. The construction Acquarotta Canal has caused significant changes in the local hydrology. According to the piezometric series recorded at several

  2. The Environmental Impact and Cost Analysis of Concrete Mixing Blast Furnace Slag Containing Titanium Gypsum and Sludge in South Korea

    Tae Hyoung Kim


    Full Text Available This study assessed the environmental effects and cost of the Industrial Waste addictive Blast Furnace Slag (W-BFS using Life Cycle Assessment (LCA and compared it to general BFS. The environmental impacts of W-BFS were as follows: 1.12 × 10−1 kg-CO2 eq/kg, 3.18 × 10−5 kg-Ethylene eq/kg, 4.79 × 10−4 kg-SO2 eq/kg, 7.15 × 10−4 kg-PO43− eq/kg, 7.15 × 10−4 kg-CFC11 eq/kg and 3.94 × 10−3 kg-Antimony eq/kg. Among the environmental impact category, GWP and AP were 9.28 × 10−2 kg-CO2 eq/kg and 3.33 × 10−4 kg-SO2 eq/kg at a raw material stage, accounting for 80% and 70% of total environmental impact respectively. In EP, POCP and ADP, in addition, raw material stage accounted for a great portion in total environmental impact because of “W” among input materials. In ODP, however, compared to the environmental impact of raw materials, oil, which was used in transporting BFS to the W-BFS manufacturing factory, was more influential. In terms of GWP, POCP and ODP, W-BFS was higher than general BFS. In terms of AP, EP and ADP, in contrast, the former was lower than the latter. In terms of cost, W-BFS (41.7 US$/ton was lower than general BFS by about 17% because of the use of waste additives comprised of industrial wastes instead of natural gypsum ,which has been commonly used in general BFS. In terms of GWP and POCP, the W-BFS mixed (30% concrete was lower than plain concrete by 25%. In terms of AP and EP, the former was lower than the latter by 30%. In terms of ADP, furthermore, W-BFS mixed (30% concrete was lower than plain concrete by 11%. In aggregate-related ODP, however, almost no change was found. In terms of cost, when W-BFS was added by 10% and 30%, it was able to reduce cost by 3% and 7% respectively, compared to plain concrete. Compared to BFS-mixed concrete as well, cost could be saved by 1% additionally because W-BFS (US$41.7/ton is lower than common cement (US$100.3/ton by about 60% in terms of production costs.

  3. 氟硅树脂石膏防水剂的制备与应用%Application and preparation of water-proofing fluorin silicon gypsum additive

    潘红; 李国忠


    以有机氟﹑有机硅以及(甲基)丙烯酸酯为原料,采用溶液聚合的方法制备了氟硅树脂防水剂,探讨了软硬单体配比、反应温度和单体投入方式对防水剂性能的影响,确定了工艺参数。研究了此防水剂对石膏试样耐水性能的影响。试验结果表明:该氟硅树脂石膏防水剂对石膏试样的短期防水性能具有显著改善,但长期使用时,防水性能有一定程度的削弱。%Organic fluorine,organic silicon,and(methyl) acrylate are used to prepare a water-proofing gypsum additive which is a fluorosilicon resin by liquor polymerization method.Effects of soft hard monomer ratio,reaction temperature and the introducing model of monomers on the properties of the waterproofing additive are discussed,and the process parameters are determined.Experiment shows that the early waterproofing performance of gypsum samples with the additive is significantly improved,but the water resistance is weakened to a certain extent for a long time.

  4. 脱硫石膏的物化特征及其综合利用%Physical and Chemical Characteristics of FGD Gypsum and Its Utilization

    曾学礼; 胡银珍; 楼文斌


    脱硫石膏是钙基湿法烟气脱硫过程中产生的副产物,产生量巨大,其综合利用为各国政府所重视。本文介绍了脱硫石膏的来源、物化特征及其影响因素和环境特征、国内外综合利用技术,并探讨了脱硫石膏资源化利用的发展趋势。%FGD gypsum is the by - product from the process of flue gas desulfurization and its output is huge whose comprehensive utilization has been much emphasized by the governments of various countries. The paper introduces the origin, the physical, chemical and environmental characteristics of FGD gypsum as well as its influence factors and the related utilization technology at home and abroad and discusses the developmental trend

  5. 磷石膏制备复相磷石膏煅烧工艺研究%Research on calcining process of duplex gypsum using phosphogypsum

    孙清臣; 杨敏


    The calcining process of duplex gypsum using phosphogypsum was studied.the results show that holding time and heating rate have an greater influence on the ratio of hemihydrate and anhydrite after phosphogypsum calcination,so dulex phosphogypsum with different ratio of hemihydrate and anhydrite can be prepared by controling holding time and heating rate during phosphogypsum with one-phase gypsum,duplex phosphogypsum possess better early strength and late strength.%  对磷石膏制备的复相石膏煅烧工艺进行了研究。结果表明:保温时间和升温速率对两种石膏的烧成比例影响较大。获得不同半水-无水比例的复相磷石膏体系可以通过控制升温速率和保温时间来实现。复相磷石膏与单相石膏比较,具有较好的早期强度和后期强度。

  6. Physical properties and cytotoxicity comparison of experimental gypsum-based biomaterials with two current dental cement materials on L929 fibroblast cells

    Nafsiyah Mahshim


    Full Text Available Aim: To evaluate physical properties and cytotoxicity of pure gypsum-based (pure-GYP and experimental gypsum-based biomaterials mixed with polyacrylic acid (Gyp-PA. The results were compared with calcium hydroxide (CH and glass ionomer cement (GIC for application as base/liner materials. Materials and Methods: Vicat′s needle was used to measure the setting time and solubility (% was determined by percentage of weight loss of the materials following immersion in distilled water. For cytotoxicity test, eluates of different concentrations of materials were obtained and pipetted onto L-929 mouse fibroblast cultures and incubated for 3 days. Cellular viability was assessed using Dimethylthiazol diphenyltetrazolium bromide test to determine the cytotoxicity level. Statistical significance was determined by one-way analysis of variance followed by post hoc test ( P Gyp-PA > CH = GIC. The pure-Gyp was found as the least cytotoxic materials at different concentrations. At 100 mg/mL dilutions of materials in growth medium highest cytotoxicity was observed with CH group. Conclusion: Cytotoxic effect was not observed with pure-Gyp; application of this novel biomaterial on deeper dentin/an exposed pulp and possibility of gradual replacement of this biodegradable material by dentin like structure would be highly promising.

  7. Use of a simplified generalized standard additions method for the analysis of cement, gypsum and basic slag by slurry nebulization ICP-OES.

    Marjanovic, Ljiljana; McCrindle, Robert I; Botha, Barend M; Potgieter, Herman J


    The simplified generalized standard additions method (GSAM) was investigated as an alternative method for the ICP-OES analysis of solid materials, introduced into the plasma in the form of slurries. The method is an expansion of the conventional standard additions method. It is based on the principle of varying both the sample mass and the amount of standard solution added. The relationship between the sample mass, standard solution added and signal intensity is assumed to be linear. Concentration of the analyte can be found either geometrically from the slope of the two-dimensional response plane in a three-dimensional space or mathematically from the ratio of the parameters estimated by multiple linear regression. The analysis of a series of certified reference materials (CRMs) (cement CRM-BCS No 353, gypsum CRM-Gyp A and basic slag CRM No 382/I) introduced into the plasma in the form of slurry is described. The slurries contained glycerol and hydrochloric acid and were placed in an ultrasonic bath to ensure good dispersion. "Table curve 3D" software was used to fit the data. Results obtained showed that the method could be successfully applied to the analysis of cement, gypsum and slag samples, without the need to dissolve them. In this way, we could avoid the use of hazardous chemicals (concentrated acids), incomplete dissolution and loss of some volatiles. The application of the simplified GSAM for the analysis did not require a CRM with similar chemical and mineralogical properties for the calibration of the instrument.

  8. Adhesives in Building--Lamination of Structural Timber Beams, Bonding of Cementitious Materials, Bonding of Gypsum Drywall Construction. Proceedings of a Conference of the Building Research Institute, Division of Engineering and Industrial Research (Spring 1960).

    National Academy of Sciences - National Research Council, Washington, DC.

    The role of adhesives in building design is discussed. Three major areas are as follows--(1) lamination of structural timber beams, (2) bonding of cementitious materials, and (3) bonding of gypsum drywall construction. Topical coverage includes--(1) structural lamination today, (2) adhesives in use today, (3) new adhesives needed, (4) production…

  9. Lime and gypsum to improve root depth of orange crop in an Ultisol of the Coastal Tablelands Calcário e gesso no aprofundamento radicular da laranjeira em um Argissolo dos Tabuleiros Costeiros

    Lafayette F. Sobral


    Full Text Available Coastal Tableland is a landscape unit in the North East of Brazil in which the main soils are Ultisols. In these soils, a compacted layer denominated "cohesive horizon" occurs and root growth is limited by it. An experiment with five treatments and six replications was set up in order to study how liming and gypsum could improve root depth of orange (Citrus sinensis L. Osbeck crop in an Ultisol in which a compacted layer was found at 0.3 m. Treatments were: A - No liming and no gypsum; B - Liming to achieve 60% base saturation; C - B + 1 t of gypsum ha-1 ; D - B + 2 t of gypsum ha-1 and E - B + 3 t of gypsum ha-1. Gypsum increased calcium and sulfate in the cohesive horizon. Surface application of lime and gypsum did not cause changes in soil density and total porosity in the cohesive horizon. An improvement of root length was observed at the cohesive horizon.Os tabuleiros costeiros são uma unidade de paisagem em que um dos principais solos são os Argissolos, nos quais, uma camada compactada, denominada "horizonte coeso" ocorre e o crescimento radicular é por ela limitado. Um experimento com cinco tratamentos e seis repetições foi implantado para se estudar os efeitos da calagem e do gesso no aprofundamento radicular da laranjeira (Citrus sinensis L. Osbeck em um Argissolo onde o horizonte coeso está a 0,3 m de profundidade. Os tratamentos foram: A - Sem gesso e sem calagem; B - Calagem para atingir 60% de saturação por bases; C - B + 1 t ha-1 de gesso ; D - B + 2 t ha-1 de gesso; e E - B + 3 t ha-1 de gesso. A calagem e o gesso aumentaram significativamente os teores de sulfato e de calcio no solo até a profundidade de 0,40 m. A aplicação a lanço de calcário e gesso não causaram modificações na densidade do solo e na porosidade total da camada compactada "horizonte coeso". Foi observado um aumento do comprimento das raízes da laranjeira na camada compactada.

  10. Resposta da alfafa a fontes de fósforo associadas ao gesso e à calagem Alfalfa response to phosphorus sources associated to gypsum and liming

    Patrícia Sarmento


    Full Text Available O fósforo é um dos nutriente mais importante na produção de alfafa nos solos brasileiros. Diversas fontes de P são disponíveis no mercado e o fosfato de Gafsa (FG é considerado tão eficiente como solúvel. A eficiência dos adubos fosfatados é afetada pela acidez do solo. O uso do gesso associado ao FG pode corrigir o perfil do solo em relação ao alumínio e diminuir a fixação do P no solo. Portanto, o objetivo deste trabalho foi avaliar num experimento em vasos a eficiência do superfosfato triplo (ST, do FG e do FG com gesso, aplicados antes e depois da calagem, nas doses de 50, 100 e 200 mg P dm-3. Foi utilizado um solo classificado como LATOSSOLO VERMELHO-AMARELO Alumínico. Foram efetuados três plantios de alfafa, realizando-se um corte no primeiro plantio e três cortes no terceiro. Com o ST obteve-se maior produção de matéria seca (MS (3,3 g/vaso do que com o FG (1,0 g/vaso no primeiro plantio. Mas no terceiro plantio ocorreu menor produção de MS com o uso do ST (2,4 g/vaso do que com o FG (6,0 g/vaso. O gesso com FG elevou a produção de MS (7,0 g/vaso em relação ao FG (3,7 g/vaso no terceiro plantio. A aplicação do ST depois da calagem aumentou a produção de MS (5,0 g/vaso comparado a aplicação antes da calagem (3,7 g/vaso, no primeiro plantio. Não houve efeito do momento de calagem para o FG com ou sem gesso.Phosphorus is one of the most important nutrients in alfalfa production in Brazilian soils. Several P sources are available in the market and the Gafsa phosphate (GP is considered as efficient and soluble. The efficiency of phosphate fertilizers is affected by soil acidity. The use of GP associated to gypsum can aliviate Al toxicity and reduce soil phosphorus fixation. Therefore, this study was curried out in a glasshouse experiment, aiming to evaluate the efficiency of the triple superphosphate (TS and GP and GP with gypsum, applied before and after liming at the rates of 50; 100 and 200 mg P dm-3. The

  11. CNC机器人七轴加工石膏模型放大雕塑%CNC robot seven axis processing gypsum model enlarged sculpture

    胡春良; 李斌


    CNC机器人七轴加工设备可实现复杂立体造型的自动化雕刻加工。简单介绍CNC机器人七轴加工石膏模型放大雕塑工艺流程。%CNC robots seven axis machining equipment is by an industrial robot arm control electric spindle, and multiple spindle automatic programming software and used to control the operation of a robotic arm software portfolio and, automatic carving processing of three-dimensional modeling of complex. Recent Chinese art casting enterprises from Italy introduced CNC robots for seven - axis machining sculpture magnifying plaster model of special equipment, realize the art casting another major leap of the large-scale sculpture lofting. This paper simply introduces the CNC robot seven axis processing gypsum model to enlarge the sculpture process.

  12. The effects of the soil improvement by the desulfurization gypsum on the agricultural production and the Tianjin economy - the case study of China's Tianjin City

    Asahi, S. [Yokkaichi University, Yokkaichi (Japan). Faculty of Environmental and Information Sciences


    This study examined the utilization of the desulfurization gypsum (by-product) as an inducement in installation the desulfurization equipment. In particular, this allocated the focus for increased yield of agricultural products by the by-product. The following conclusions can be drawn from this analysis. In the case where the soil was improved on a quarter of the arable land of the corn, the rate of the increase in 1995 was 1.85% of the total output for corn in Tianjin city. A year later, in 1996, the rate increased by 4.25% of total output for corn. Increased production by the soil improvement in the first year is equal to about 22000 persons, when increased production is evaluated at the consumption rate per farming village in China, and the repercussion effect of the increased yield of agricultural products benefits mostly the industrial sector. 6 refs., 1 fig., 2 tabs.

  13. Corrosion resistance of various bio-films deposited on austenitic cast steel casted by lost-wax process and in gypsum mould

    J. Gawroński


    Full Text Available This work is the next of a series concerning the improvement of austenitic cast steel utility predicted for use in implantology for complicated long term implants casted by lost-wax process and in gypsum mould. Austenitic cast steel possess chemical composition of AISI 316L medical steel used for implants. In further part of present work investigated cast steel indicated as AISI 316L medical steel. Below a results of electrochemical corrosion resistance of carbon layer and bi-layer of carbon/HAp deposited on AISI 316L researches are presented. Coatings were manufactured by RF PACVD and PLD methods respectively. Obtained results, unequivocally indicates on the improvement of this type of corrosion resistance by substrate material with as deposited carbon layer. While bi-layer of carbon/HAp are characterized by very low corrosion resistance.

  14. The Potential Ability of Plaster to Cause Breast Cancer as Indicated by CA15-3 and CEA Antigens in Women Working in Gypsum Factory

    Ali Abdul Hussein S. AL-Janabi


    Full Text Available Plaster is an important form of gypsum that mainly used in building construction. Breast cancer was investigated among women exposure to the dust of such material. The levels of CA15-3 and carcinoembryonic antigens (CEA as indicators for breast cancer were measured in the serum of 120 women working in a plaster factory. All of involved women showed a normal level of CEA, while 12.5% of them had moderately elevated levels of CA15-3. In conclusion; plaster dust has no significant effect to cause breast cancer in working women. Moderately high levels of CA15-3 in some of exposed women may relate to liver diseases. Key words: Breast Cancer, Plaster, CA15-3, CEA

  15. SO/sub 2/ scrubbing downstream of combustion systems with raw gypsum as final product. SO/sub 2/-Waschung hinter Verbrennungsanlagen mit Rohgips als Endprodukt

    Hoelter, H.; Igelbuescher, H.; Gresch, H.; Dewert, H.


    This flue gas purification method first purifies the crude gas from HCl and HF in the prescrubber and from SO/sub 2/ and/or NO/sub x/ in the main scrubber. The CaSO/sub 3//CaSO/sub 4/ product occurring in the main scrubber is, according to the invention, pumped through a pipe into the prescrubber. In this process a well-oxidized CaSO/sub 4/ product with adequate content of calcium chloride develops in the scrubber liquid because of the high quantity of excess atmospheric oxygen in the crude gas. In this way raw gypsum is enriched by chlorides and can be directly used as building material, e.g. in mines. Thus, the salt load in the prescrubber is reduced.

  16. Impact experiments of porous gypsum-glass bead mixtures simulating parent bodies of ordinary chondrites: Implications for re-accumulation processes related to rubble-pile formation

    Yasui, M.; Arakawa, M.


    Most of asteroids are expected to be impact fragments produced by collisions among planetesimals or rubble-pile bodies produced by re-accumulation of fragments. In order to study the formation processes of asteroids, it is necessary to examine the collisional disruption and re-accumulation conditions of planetesimals. Most of meteorites recovered on the Earth are ordinary chondrites (OCs). The OCs have the components of millimeter-sized round grains (chondrules) and submicron-sized dusts (matrix). So, the planetesimals forming the parent bodies of OCs could be mainly composed of chondrules and matrix. Therefore, we conducted impact experiments with porous gypsum mixed with glass beads having the spherical shape with various diameters simulating chondrules, and examined the effect of chondrules on the ejecta velocity and the impact strength. The targets included glass beads with a diameter ranging from 100 μm to 3 mm and the volume fraction was 0.6, similar to that of ordinary chondrites, which is about 0.65-0.75. We also prepared the porous gypsum sample without glass bead to examine the effect of volume fraction. Nylon projectiles with the diameters of 10 mm and 2 mm were impacted at 60-180 m/s by a single-stage gas gun and at about 4 km/s by a two-stage light gas gun, respectively. After the shot, we measured the mass of the recovered fragments to calculate the impact strength Q defined by Q=mpVi^2/2(mp+Mt), where Vi is the impact velocity, and mp and Mt are the mass of projectile and target, respectively. The collisional disruption of the target was observed by a high-speed video camera to measure the ejecta velocity. The antipodal velocity Va increased with the increase of Q, irrespective of glass bead size and volume fraction. However, the Va for low-velocity collisions at 60-180 m/s was an order magnitude larger than that for high-velocity collisions at 4 km/s. The velocities of fragments ejected from two corners on the impact surface of the target Vc

  17. Production development and utilization of Zimmer Station wet FGD by-products. Final report. Volume 6, Field study conducted in fulfillment of Phase 3 titled. Use of FGD by-product gypsum enriched with magnesium hydroxide as a soil amendment

    Bigham, J. M. [Ohio State Univ., Wooster, OH (United States). Ohio Agricultural Research Development Center; Soto, U. I. [Ohio State Univ., Wooster, OH (United States). Ohio Agricultural Research Development Center; Stehouwer, R. C. [Ohio State Univ., Wooster, OH (United States). Ohio Agricultural Research Development Center; Yibirin, H. [Ohio State Univ., Wooster, OH (United States). Ohio Agricultural Research Development Center


    A variety of flue gas desulfurization (FGD) technologies have been developed to meet environmental restrictions imposed by the federal Clean Air Act and its amendments. These technologies include wet scrubber systems that dramatically reduce sulfur dioxide (SO2) emissions. Although such systems are effective, they also produce large volumes of sludge that must be dewatered, stabilized, and disposed of in landfills. Disposal is an expensive and environmentally questionable process for which suitable alternatives are needed. Wet scrubbing of flue gases with magnesium (Mg)-enhanced lime has the potential to become a leading FGD technology. When combined with aforced oxidation system, the wet sludges resulting from this process can be modified and refined to produce gypsum (CaS04∙2H2O) and magnesium hydroxide [Mg(OH)2] of sufficient purity for beneficial re-use in the construction (wallboard) and pharmaceutical industries. The pilot plant at the CINERGY Zimmer Station near Cincinnati can also produce gypsum by-products formulated to contain varying amounts of Mg(OH)2- Such materials may have value to the agriculture, forestry, and lawn-care industries as soil "conditioners", liming agents, and nutritional supplements capable of supplying calcium (Ca), Mg, and sulfur (S) for plant growth. This report describes three field studies designed to evaluate by-product gypsum and Mg-gypsum from the Zimmer Station power plant as amendments for improving the quality of mine spoils and agricultural soils that were unproductive because of phytotoxic levels of dissolved aluminum (Al) and low pH. The technical literature suggests that gypsum may be more effective than agricultural limestone for ameliorating Al toxicity below the immediate zone of application. Such considerations are important for deep-rooted plant species that attempt to utilize water and nutrients occurring at depth in the spoil/soil.

  18. Preparation of Calcium Sulfate Whiskers from Phosphorus Gypsum%磷石膏制备硫酸钙晶须的工艺研究

    周华锋; 张肖肖; 李响


    采用常压酸化法对磷石膏分别进行硫酸除杂和盐酸溶解,将磷石膏中的钙富集于溶解液中.再对溶液进行处理制备硫酸钙晶须,考察硫酸钙初始浓度、结晶温度及添加助晶剂种类和用量对硫酸钙晶须组成、结构和形貌的影响.实验结果表明:所制晶须均为二水硫酸钙晶须;以乙醇作为助晶剂所制备的晶须形貌最好.当乙醇的添加量为15 mL(即V乙醇∶V盐酸=1∶2)时所制备的晶须比较均一,平均直径为25 μm,平均长径比约为80.%The phosphate gypsum was dissolved in sulfuric acid solution to remove the impurities and then the insoluble solid was dissolved in hydrochloric acid at normal pressure, the calcium in the phosphorus gypsum was enriched in the solution.The calcium sulfate whiskers were prepared by treating the solution.The effects of initial concentration of calcium sulfate, crystallization temperature, the types and amount of crystallization promoting agents on the content, structure and morphology of calcium sulfate whiskers were investigated.The results show that the whiskers are calcium sulfate dihydrate;Ethanol is the best crystallization promoting agent;The uniform whiskers with diameter of 25 μm, aspect ratio of about 80 is prepared when the amount of ethanol is 15 mL(Vethanol∶Vhydrochloric acid=1∶2).

  19. Progress in Researches of Gypsum Paraffin Phase Change Energy Storage Wallboard%石膏基石蜡相变储能墙板的研究进展

    刘永明; 李东旭


    Resource and energy consumption of buildings construction is large, building energy-saving should be implemented to improve energy efficiency. Energy can be stored by large heat fusion that phase change materials (PCM) release and absorb when phase change, and paraffin wax is safe, cheap PCM, having good chemical stability, large heat fusion and no super cooling, so it was choosed as PCM to be added to gypsum wallboards, which is low in production energy consumption, to get gypsum paraffin phase change energy storage wallboards. The domestic and foreign reaserch and development of PCM wallboards are introduced, and the preparation, packaging of paraffin composite used as PCM, manufacture process and related properties of PCM wallboards are reviewed.%建筑是资源和能源消耗大户,应实施建筑节能来提高能源利用效率.利用相变材料在相变过程中释放和吸收大量相变热可进行能量的存储,因石蜡是安全、无过冷、化学稳定性好、相变潜热较大且价廉的相变材料,将石蜡作为相变材料引入到生产能耗低的石膏墙板制作石膏基石蜡相变储能墙板具有重要意义.介绍了国内外相变储能墙板材料的研究现状,同时综述了石膏基石蜡相变储能墙板中石蜡相变材料的复配和封装、相变墙板的制作工艺及相关性能.

  20. Solubility Measurements and Predictions of Gypsum, Anhydrite, and Calcite Over Wide Ranges of Temperature, Pressure, and Ionic Strength with Mixed Electrolytes

    Dai, Zhaoyi; Kan, Amy T.; Shi, Wei; Zhang, Nan; Zhang, Fangfu; Yan, Fei; Bhandari, Narayan; Zhang, Zhang; Liu, Ya; Ruan, Gedeng; Tomson, Mason B.


    Today's oil and gas production from deep reservoirs permits exploitation of more oil and gas reserves but increases risks due to conditions of high temperature and high pressure. Predicting mineral solubility under such extreme conditions is critical for mitigating scaling risks, a common and costly problem. Solubility predictions use solubility products and activity coefficients, commonly from Pitzer theory virial coefficients. However, inaccurate activity coefficients and solubility data have limited accurate mineral solubility predictions and applications of the Pitzer theory. This study measured gypsum solubility under its stable phase conditions up to 1400 bar; it also confirmed the anhydrite solubility reported in the literature. Using a novel method, the virial coefficients for Ca2+ and {{SO}}4^{2 - } (i.e., β_{{{{CaSO}}4 }}^{(0)} ,β_{{{{CaSO}}4 }}^{(2)} ,C_{{{{CaSO}}4 }}^{φ }) were calculated over wide ranges of temperature and pressure (0-250 °C and 1-1400 bar). The determination of this set of virial coefficients widely extends the applicable temperature and pressure ranges of the Pitzer theory in Ca2+ and SO 4 2- systems. These coefficients can be applied to improve the prediction of calcite solubility in the presence of high concentrations of Ca2+ and SO 4 2- ions. These new virial coefficients can also be used to predict the solubilities of gypsum and anhydrite accurately. Moreover, based on the derived β_{{{{CaSO}}4 }}^{(2)} values in this study, the association constants of {{CaSO}}4^{( 0 )} at 1 bar and 25 °C can be estimated by K_{{assoc}} = - 2β_{{{{CaSO}}4 }}^{(2)}. These values match very well with those reported in the literature based on other methods.

  1. Mechanisms of karst breakdown formation in the gypsum karst of the fore-Ural region, Russia (from observations in the Kungurskaja cave.

    Klimchouk Alexander


    Full Text Available The fore-Ural is a classical region of intrastratal gypsum karst. The intensive development of karst in the Permian gypsums and anhydrites causes numerous practical problems, the subsidence hazard being the most severe. Mechanisms of karst breakdown formation were studied in detail in the Kunguskaya Cave area. The cave and its setting are characteristic to the region and, being a site of detalied stationary studies for many years, the cave represents a convenient location for various karst and speleological investigations. Breakdown structures related to cavities of the Kungurskaya Cave type develop by two mechanisms: gravitational (sagging and fall-in of the ceilings of cavities and filtrational/gravitational (crumbling and fall-in of the ceilings of vertical solution pipes, facilitated by percolation. The former implies upward stoping of the breakout roof and cessation of the process at some height above the floor of the cave due to complete infilling by fallen clasts. This mechanism cannot generate surface deformation where the overburden thickness exceeds a certain value. The latter mechanism implies that breakdown will almost inevitably express itself at the surface, most commonly as a sudden collapse, even where the thickness of the overburden is large. These mechanisms resuit in different appearance, distribution and further evolution of the respective surface forms, so that subsidence hazard assessment should be performed differently for these types of breakdown. The conclusions reached by this study are representative for the region, although some of them bear more general validity for intrastratal karst conditions. This study underlines the ultimate importance of speleological investigations to the understanding of karst breakdown mechanisms.

  2. Current research situation of Gypsum pieces and its packaging storage technology%石膏饮片及其包装贮藏技术研究现状

    潘蕾; 钟凌云


    本文在广泛文献检索基础上,首先重点阐述了石膏的化学成分、药理作用、炮制工艺等方面的研究概况,为进一步提高石膏炮制的工艺水平、制订统一操作规程提供相关的理论依据;其次根据石膏饮片的入药形式及物理性质,系统地概述了不同包装材料和贮藏方法的优缺点,为找出经济的、有效的、且操作简便的包装材料及贮藏技术提供思路和方法,以期实现中药饮片包装标准化、规范化、合理化,促进石膏饮片在临床上的有效应用.%Based on the extensive literature retrieve, the article firstly focuses on stating gypsum chemical composition, pharmacological effects, processing technology, and other aspects of the research, to further improve the level of technology, and provides realated theroy evidence for formulating operation specifications; secondly systematically describe merits and shortcoming of different packaging and storage methods, according to its form and physical characters, and provides thought and method for finding economic, effective, convenient packaging metcrals and storage technology, so as to achieve standardization, rationalization, promotes further development of gypsum pieces on clinical application.

  3. The Influence of FeS on the Thermal Decomposition Characteristics of Gypsum in the Nitrogen Atmosphere%氮气气氛下FeS对二水石膏热分解特性的影响

    张亚杰; 贾兴文


    To study the influence of FeS, as reducing agent, on thermal decomposition characteristics of gypsum and to calculate the active energy required for gypsum decomposition with different proportion of reducing agent, the method of TG-DSC and the model of Coats-Redfem were adopted respectively. The study used Nitrogen as carrier gas to prevent reducing agent from oxidation. Results showed that when the ration of molar mass between FeS and gypsum was increased from 1 : 22 to 3 : 22, the activation energy value decreased from 327 kJ/mol to 214 kJ/ mol; accordingly, the initial decomposition temperature fell from 1350 ℃ to 998 ℃. The decomposition characteristics of gypsum represented similar tendency when the molar mass ratio of coke and gypsum increased from 1 : 2 to 2 : 1 apart from a slump in the initial decomposition temperature from 1350 ℃ to 956 ℃. Besides, the product Fe2O3 has positive effects on the sequential decomposition,of gypsum.%采用TG-DSC方法分析FeS做还原剂时化学纯石膏的热分解特性,并利用Coats-Redfem模型计算还原剂掺量不同时石膏分解的活化能值.为防止还原剂被氧化选择氮气作为载气流.结果表明,焦炭与石膏摩尔比从1∶2增加到2∶1时,石膏分解所需的活化能从327 kJ/mol降低到210 kJ/mol,起始温度从1350℃降到956℃;FeS与石膏的摩尔比从1∶22增加到3∶22时,石膏分解所需的活化能值从327 kJ/mol降低到214 kJ/mol,起始分解温度从1350℃降低到998℃,同时生成的产物Fe2O3对石膏的分解有促进作用.

  4. Effects of inorganic amendments (urea, gypsum) on seed germination and seedling recruitment of 20 native plant species used in dryland restoration

    Bateman, Amber; E Erickson, Todd; Merritt, David J.; Muñoz-Rojas, Miriam


    Introduction Soil health and functionality are major determining factors for restoration of degraded arid and semi-arid ecosystems. These highly nutrient impoverished soil substrates with low water retention capabilities dictate plant growth and survival in these landscapes that are subject to variable rainfall event and high temperatures (Muñoz-Rojas et al., 2016). Anthropogenic disturbances derived from mining activities have contributed to the degradation of soil functionality and have altered plant-soil-water interactions. With unknown positive or negative rehabilitation outcomes, inorganic amendments in the form of urea and gypsum are commonly added to reconstructed soil substrates disturbed by mining to replenish soil nutrients (nitrogen) and improve soil water holding capacity to improve seedling establishment and survival. Methods Using existing protocols for amendment addition to soil substrates, two experiments assessed the effects of urea and gypsum at multiple doses in reconstructed soil substrates (topsoil (TS), waste (W) and, 50:50 blend of both materials (TW) to evaluate its effectiveness as a supplement to improve seed germination, seedling recruitment and plant growth. In the first experiment, 20 species native to the resource-rich biodiverse Pilbara region of Western Australia were grown in 30 °C glasshouse facilities under well-watered conditions for three weeks with seedling emergence scored daily. At the end of the trial, seedlings were harvested and biomass was assessed. In the second experiment, five of the original 20 species (e.g. Acacia bivenosa, Gossypium robinsonii, Eucalyptus gamophylla, Triodia wiseana and, Senna notabilis) were assessed for germination in amended soils by burying nylon sachets in the reconstructed substrates. After three weeks, the sachets were retrieved and seeds were assessed for germination (i.e. radicle emergence was evident). Results and Discussion Total emergence and biomass of seedlings was negatively

  5. Evolution of mechanical properties of a residue from the secondary aluminium remelting industry stabilized with gypsum; Evolucion de las propiedades mecanicas de un residuo de la metalurgia secundaria del aluminio estabilizado con yeso

    Tayibi, H.; Perez, C.; Lopez, F. A.; Lopez-Delgado, A.


    Aluminium dust from aluminium remelting industry is a hazardous residue because of its high reactivity in the presence of water (production of ammonia, methane, hydrogen sulphide...) potential aluminothermy and its content in leaching heavy metals. In order to apply the new European Directive about landfill of waste, a Stabilization/Solidification (S/S) process was developed in the CENIM with the aim of decreasing its reactivity and to assure an easy transport and storage of the residue. Gypsum was used as a binder material. This work summarizes the study of the mechanical properties of the stabilized residue en comparison with the gypsum ones. The reactivity of the dust, before and after the S/S process was investigated by analysing the ammonia and metallic aluminium. (Author) 16 refs.

  6. 建筑石膏基相变储能材料的制备与分析%Preparation and analysis of gypsum-based phase change energy storage materials in building



    以石膏为载体,癸酸和月桂酸二元混合酸为相变材料,通过实验确定石膏基相变储能材料的制备工艺,并详细分析其容留量、渗出程度及热物性能,得出了一些有价值的结论,以供参考借鉴。%Taking gypsum as the carrier,and taking the binary mixed acid of caproleric acid and lauric acid as PCM,the paper determines the prefabrication technology of PCM with gypsum foundation,specifically analyzes its capacity,leakaging degree and thermophysical properties,and finally draws some valuable conclusions,with a view to provide some guidance.


    吴世莲; 陆林侦; 曹明国; 查光玉


    Objective To study the influences of three kinds of disinfection methods on compressive strength of oral gypsum models. Methods On physical multi - function experimental bench the compressive strength of oral gypsum models was tested after microwave disinfection, pressure steam sterilization and ultraviolet irradiation disinfection. Results The compressive strength of three kinds of gypsum models including plaster, dental stone, high strength dental stone treated by microwave disinfection was slightly lower than that of the control group, but the difference had no statistical significance (P > 0.05). In addition to the gypsum models of high strength dental stone, the compressive strength of the other two kinds of gypsum models treated by ultraviolet irradiation disinfection was slightly lower too. The compressive strength of three kinds of gypsum models treated by pressure steam sterilization was significantly lower than that of the control group. Differences between the two groups of data were statistically significant (P < 0. 01). Conclusion Disinfection by microwave heating and ultraviolet irradiation do not obviously affect the compressive strength of oral gypsum models, but disinfection by pressure steam sterilization obviously affect the compressive strength of oral gypsum models.%目的 研究三种消毒方法对口腔石膏模型压缩强度的影响.方法 采用物理多功能试验台,对微波消毒法、压力蒸汽灭菌法和紫外线照射法消毒后的口腔石膏模型压缩强度进行了测试.结果 微波消毒法处理后的熟石膏、硬石膏和超硬石膏模型等种类石膏模型的压缩强度均略低于对照组压缩强度,但两组数据差异没有显著统计学意义(p>0.05);紫外线照射消毒法除超硬石膏模型之外,对另两种模型压缩强度也略有降低.压力蒸汽灭菌处理后的三种石膏模型的压缩强度明显低于对照,两组数据比较差异有显著统计学意义(p<0.01).结论 微

  8. Operating experience with the FGD wet scrubbing process and gypsum processing at VEAG`s Jaenschwalde power station; Erste Betriebserfahrungen mit dem REA-Nasswaschverfahren und der Gipsverwertung im VEAG-Kraftwerk Jaenschwalde

    Sparmann, A.; Liebmann, V. [VEAG Vereinigte Energiewerke AG, Kraftwerk Jaenschwalde, Peitz (Germany); Lemke, D. [VEAG Vereinigte Energiewerke AG, Hauptlabor, KTHZ, Berlin (Germany)


    The flue gas desulphurization plant with a dual-circuit wet-scrubbing process operating in the Jaenschwalde power station meets the scrubber efficiency requirement of >95% for the SO{sub 2} minimization. The caking encountered in the absorber and absorber supply tank was reduced leaving only a negligible residue. Specific changes to the gypsum crystal morphology by adjusting the dwell time stabilized the gypsum quality. Continuation of absorber systems after failure of the limestone supply is ensured for a period of 15 to 20 hours. (orig.) [Deutsch] Die im Zweikreis-Waschverfahren arbeitende Rauchgasentschwefelungsanlage (REA) im Kraftwerk Jaenschwalde erfuellt den Waescherwirkungsgrad zur SO{sub 2}-Minimierung von > 95%. Die im Absorber und Absorberversorgungsbehaelter aufgetretenen Anbackungen wurden bis auf unbedeutende Reste reduziert. Eine gezielte Veraenderung der Gipskristallmorphologie durch Verweilzeitanpassung fuehrte zur Stabilisierung der Gipsqualitaet. Der Weiterbetrieb der Absorbersysteme ist bei Ausfall der Kalksteinversorgung fuer 15 bis 20 Stunden gesichert. (orig.)

  9. Thermal Dehydration Kinetics of Gypsum and Borogypsum under Non-isothermal Conditions%在非等温条件下石膏和硼石膏的加热脱水动力学研究

    ī.Y.Elbeyli; S.Piskin


    Thermal dehydration of gypsum and borogypsum was investigated under nonisothermal conditions in air by using simultaneous thermogravimetric-differential thermal analyzer. Nonisothermal experiments were carried out at various linear heating rates. Kinetics of dehydration in the temperature range of 373-503 K were evaluated from the DTA (differential thermal analysis)-TGA (thermogravimetric analysis) data by means of Coats-Redfern,Kissinger and Doyle Equations. Values of the activation energy and the pre-exponential factor of the dehydration were calculated. The results of thermal experiments and kinetic parameters indicated that borogypsum is similar to gypsum from dehydration mechanism point of view although it consists of boron and small amount of alkali metal oxides.

  10. 湿烟囱出口“石膏雨”的成因及防治措施分析%Analysis and Countermeasure to “Gypsum Rain” Problem at the Outlet of Wet Stack

    陈世新; 杨涛


    “Wet stack” has been applied in most of power plants.“gypsum rain” problem impact on the surrounding environment. An analysis is conducted on the causes of the liquid drips carried byflue gas at the outlet of stack and Some measures are proposed in this paper to reduce“gypsum rain” phenomenon.%火力发电厂湿法脱硫后均采用“湿烟囱”排放方案,产生的“石膏雨”现象带来严重的环境影响和危害,本文对湿烟囱烟气携带液滴来源进行分析,并提出防治措施,减少石膏雨的产生。

  11. Surface application of gypsum in low acidic Oxisol under no-till cropping system Aplicação superficial de gesso num Latossolo de baixa acidez sob sistema plantio direto

    Eduardo Fávero Caires


    Full Text Available The conditions in which a favorable response to a gypsum application can be expected on crop yields are not clear. A 3-year field trial was carried out to evaluate the effects of gypsum application on soil chemical attributes and nutrition and yield of corn (Zea mays L. and soybean (Glycine max L. Merrill on a clayey Typic Hapludox of high fertility and low acidity under no-till in Guarapuava, Parana State, Brazil. Treatments were arranged in a randomized complete block design with four replications, and consisted of gypsum application on the soil surface at 4, 8, and 12 Mg ha-1. Gypsum application increased the P content in the soil most superficial layer (0.0 - 0.1 m and also the exchangeable Ca and S-SO4(2- contents and the Ca/Mg ratio in the soil profile (0.0 - 0.6 m. Gypsum also caused leaching of Mg and K exchangeable in the soil. An increase in Ca concentrations in the corn leaves, and in P and S concentrations in the corn and soybean leaves occurred following the gypsum application. A yield response of corn to initial application of gypsum was found, but subsequent soybean crops did not respond. Gypsum application proved to be an effective practice to maximize no-till corn grain yield.Não estão claras as condições em que se podem esperar efeitos favoráveis da aplicação de gesso na produção das culturas. Em um experimento de campo avaliaram-se, durante três anos, os efeitos da aplicação de gesso nos atributos químicos de um Latossolo Vermelho argiloso de alta fertilidade e baixa acidez sob plantio direto e na nutrição e produção de milho (Zea mays L. e soja (Glycine max L. Merrill, em Guarapuava (PR. Os tratamentos, dispostos em blocos completos ao acaso com quatro repetições, constaram da aplicação superficial de gesso nas doses 4, 8 e 12 Mg ha-1. A aplicação de gesso aumentou a concentração de P na camada mais superficial (0.0 - 0,1 m, bem como os teores de Ca trocável e de S-SO4(2- e a relação Ca/Mg no

  12. Precise and accurate isotope fractionation factors (α17O, α18O and αD) for water and CaSO4·2H2O (gypsum)

    Gázquez, Fernando; Evans, Nicholas P.; Hodell, David A.


    Gypsum (CaSO4·2H2O) is a hydrated mineral containing crystallization water, also known as gypsum hydration water (GHW). We determined isotope fractionation factors (α17O, α18O and αD) between GHW and free water of the mother solution in the temperature range from 3 °C to 55 °C at different salinities and precipitation rates. The hydrogen isotope fractionation factor (αDgypsum-water) increases by 0.0001 units per °C between 3 °C and 55 °C and salinities paleoclimate applications. Between 3 °C and 55 °C, α18Ogypsum-water averages 1.0035 ± 0.0002. This value is more precise than that reported previously (e.g. 1.0041 ± 0.0004 at 25 °C) and lower than the commonly accepted value of 1.004. We found that NaCl concentrations below 150 g/L do not significantly affect α18Ogypsum-water, but αDgypsum-water increases linearly with NaCl concentrations even at relatively low salinities, suggesting a salt correction is necessary for gypsum formed from brines. Unlike oxygen isotopes, the αDgypsum-water is affected by kinetic effects that increase with gypsum precipitation rate. As expected, the relationship of the fractionation factors for 17O and 18O follows the theoretical mass-dependent fractionation on Earth (θ = 0.529 ± 0.001). We provide specific examples of the importance of using the revised fractionation factors when calculating the isotopic composition of the fluids.

  13. Mineral potential of clays that cover the gypsum deposits in Araripina-PE region; Potencial mineral das argilas que recobrem as jazidas de gipsita na regiao de Araripina-PE

    Lira, B.B.; Anjos, I.F. dos, E-mail: [Universidade Federal da Paraiba (CT/UFPB), PB (Brazil); Rego, S.A.B.C. [Universidade Federal de Pernambuco (PGEM/DEMEC/UFPE), PE (Brazil)


    In the present work the applicability of the clays that cover the deposits of Gypsum Plaster in the region of Araripina - PE for use as the ceramic pigments and for bricks production in the red ceramic industry was analyzed. The clay minerals contained the illite, kaolinite and smectite, with high proportion of the last one. The possibility of industrial application of this mineral clay is considerable; however, the mining industries that mine and process the gypsum in the region do not take the clays into account as the potential mineral. In general, industries use the clay minerals in manufacturing processes or as key raw materials, or as the alternatives for some kinds of the chemical processing industries. This paper aims to highlight the potential of materials that cover the deposits of gypsum in reference. The material sampled from different deposit layers was characterized and the physical treatment of ore was applied. The results showed that the material analyzed can be used in various kinds of industry, such as the production of natural ceramic pigments. (author)

  14. Co-treatment of gypsum sludge and Pb/Zn smelting slag for the solidification of sludge containing arsenic and heavy metals.

    Li, Yuan-Cheng; Min, Xiao-Bo; Chai, Li-Yuan; Shi, Mei-Qing; Tang, Chong-Jian; Wang, Qing-Wei; Liang, Yan-Jie; Lei, Jie; Liyang, Wen-Jun


    Wastewater treatment sludge from a primary lead-zinc smelter is characterized as hazardous waste and requires treatment prior to disposal due to its significant arsenic and heavy metals contents. This study presents a method for the stabilization of arsenic sludge that uses a slag based curing agent composed of smelting slag, cement clinker and limestone. The Unconfined Compressive Strength (UCS) test, the China Standard Leaching Test (CSLT), and the Toxicity Characteristic Leaching Procedures (TCLP) were used to physically and chemically characterize the solidified sludge. The binder ratio was determined according to the UCS and optimal experiments, and the optimal mass ratio of m (smelting slag): m (cement clinker): m (gypsum sludge): m (limestone) was 70:13:12:5. When the binder was mixed with arsenic sludge using a mass ratio of 1:1 and then maintained at 25 °C for 28 d, the UCS reached 9.30 MPa. The results indicated that the leached arsenic content was always less than 5 mg/L, which is a safe level, and does not contribute to recontamination of the environment. The arsenic sludge from the Zn/Pb metallurgy plant can be blended with cement clinker and smelting slag materials for manufacturing bricks and can be recycled as construction materials. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. The influence of flue gas desulphurization gypsum additive on characteristics and evolution of humic substance during co-composting of dairy manure and sugarcane pressmud.

    Guo, Xiaobo; Huang, Junhao; Lu, Yanyu; Shan, Guangchun; Li, Qunliang


    For the purpose of evaluating the effect of flue gas desulphurization gypsum (FGDG) additive on characteristics and evolution of humic substance (HS) during composting, HS from composts with FGDG (CPG) and without FGDG (CP) were extracted and assessed with respect to their particle size, elemental analysis, FTIR and UV-vis spectroscopy, and the molecular composition of HS was characterized via pyrolysis-GC/MS as well. The particle size of HS ranged between 300 and 600nm, representing a bimodal distribution. As composting proceeded, the C/H of HS increased, and C/N decreased. The FTIR and UV-vis spectroscopy indicated that the aromatization of HS was promoted over the composting process. Adding FGDG increased the unsaturated degree and aromatization of HS. Pyrolysis-GC/MS showed the level of alkane decreased, and the level of benzene and nitrogen compounds increased upon the addition of FGDG. The nitrogen compounds of HS in CPG was significantly higher than that in CP.

  16. Early age hydration of calcium sulfoaluminate (synthetic ye'elimite, ) in the presence of gypsum and varying amounts of calcium hydroxide

    Hargis, Craig W.


    Suspensions of synthetic ye\\'elimite (C4A3S̄) in a saturated gypsum (CS̄H2) and calcium hydroxide (CH) solution were examined in-situ in a wet cell by soft X-ray transmission microscopy and ex-situ by scanning electron microscopy. The most voluminous hydration product observed was ettringite. Ettringite commonly displayed acicular, filiform, reticulated, and stellate crystal habits. Additionally, pastes with C 4A3S̄, 15% CS̄H2, and varying amounts of CH were prepared and examined with X-ray diffraction (XRD) and isothermal calorimetry. The XRD experiments showed that increasing CH content caused more solid solution (SO4 2 -/OH-) AFm phases to form at early ages (< 1 d) and more monosulfate to form at later ages (> 1 d). Calorimetry indicated that the increased production of solid solution AFm was accompanied with an increase in the initial (< 30 min) rate of heat evolution, and increasing CH generally reduced the time till the second maximum rate of heat evolution due to the formation of ettringite and monosulfate. © 2013 Elsevier Ltd.

  17. Potential use of gypsum and lime rich industrial by-products for induced reduction of Pb, Zn and Ni leachability in an acid soil

    Rodriguez-Jorda, M.P. [Instituto de Ciencias Agrarias, Centro de Ciencias Medioambientales, Consejo Superior de Investigaciones Cientificas, Serrano 115 dpdo, 28006 Madrid (Spain); Garrido, F., E-mail: [Instituto de Ciencias Agrarias, Centro de Ciencias Medioambientales, Consejo Superior de Investigaciones Cientificas, Serrano 115 dpdo, 28006 Madrid (Spain); Garcia-Gonzalez, M.T. [Instituto de Ciencias Agrarias, Centro de Ciencias Medioambientales, Consejo Superior de Investigaciones Cientificas, Serrano 115 dpdo, 28006 Madrid (Spain)


    This study evaluates the potential use of four industrial by-products (phosphogypsum (PG), red gypsum (RG), sugar foam (SF), and ashes from biomass combustion (ACB)), applied at two rates in single and combined amendments to reduce the mobility and availability of Pb, Zn and Ni in a metal-spiked acid soil. Leaching experiments were done to estimate leachability indexes and assess their effectiveness. Most of the treatments significantly reduced the metal leachability although only a few were effective for all metals. Based on principal component and cluster analysis, sugar foam (SF) and a mixture of RG and ACB (RG+ACB), both applied at high rate, were selected as first choices to reduce mobility and availability of the three metals. Metal sorption mechanisms involved in the reduction of their leachability were identified using scanning electron microscopy. In the SF-treated samples, the metals were found associated to amorphous Al-hydroxy polymers deposited on phyllosilicates and organic matter particles. In the (RG+ACB)-treated samples, Pb, Zn, and traces of Ni were found associated to Fe/Ti oxide phases with a significant concentration of S, suggesting the formation of metal-sulfate ternary complexes.

  18. Study onmodification of thermal insulation material of FGD gypsum-based%脱硫石膏基保温材料的改性研究

    于秋仙; 薛力梨; 王启湘; 杨金根; 孙溪禧; 袁波


    Two waste generated by the thermal power, desulphurization gypsum and fly ash, compound with foam glass scrap, vitrified micro bead thermal insulation materials and additives to execute Thermal insulation board,to study the mechanical properties and thermal properties, and the application prospect is analyzed. Results show that the heat preservation plate compressive strength more than 0.7MPa, the thermal conductivity between the 0.10-0.12w/ (m·k), dry table view the minimum density can reach 675kg/m3.%将火力发电产生的脱硫石膏和粉煤灰两大废弃物,与泡沫玻璃边角料、玻化微珠等保温材料以及外加剂等复合制备保温板,研究其力学性能和保温性能,并分析其应用前景.结果表明:制得的保温板抗压强度在0.7MPa以上,导热系数在 0.10-0.12w/(m.k)之间,干表观密度最小可以达到675kg/m3.

  19. Influence of the errors in an infrared camera on the estimation of thermal conductivity and thermal capacity of a gypsum plaster sample

    Santana Magnani, Fábio; Nunes Tavares da Silva, Renata


    The present work studies how the errors of infrared cameras propagate during the estimation of thermophysical parameters. The errors in the camera were determined experimentally, and varied with both position and temperature. The thermal conductivity and thermal capacity were estimated by comparing the experimental and computational temperature evolution as a gypsum plaster sample was left to cool naturally in the air. For each study, one of the parameters was varied until the simulated temperature curve was adjusted to the experimental curve using the Levenberg-Marquardt Algorithm. We concluded that for the thermal capacity, there is a strong correlation between the error in the camera and the error of the parameter, which was not so clear in the case of the thermal conductivity. Another important conclusion is that the variation of the thermal conductivity presents a better adjustment of the curves even though the error in the estimated parameter was higher, indicating that reasonable results in the minimization process do not necessarily assure a good estimation. As a final conclusion, we stress the importance of using calibrated cameras, since in the extreme cases a mean deviation of 1.46 °C in the camera represented an error of 15% on the thermal capacity and a mean deviation of 0.81 °C in the camera represented an error of 25% on the thermal conductivity.

  20. 石膏种类对富水充填材料凝结硬化性能与机理的影响%Impact of gypsum type on the setting and hardening performance and mechanism of water-rich filling materials

    刘娟红; 马翼; 王祖琦; 高萌; 周茜


    As for the problem that different gypsum types have different influence on the condensation performance of water-rich filling materials, micro experiments, such as X-ray diffraction, scanning electron microscopy and infrared spectroscopy, were used to analyze the composition of the hardened body and investigate the influence of dihydrate gypsum and hemihydrate gypsum on the setting and hardening characteristics of water-rich filling materials. It is found that in a water-rich filling material system of sulphoaluminate cement-gypsum-lime, the gypsum type should be dihydrate gypsum so as to ensure the normal condensation setting and hardening;if hemihydrate gypsum is used as a raw material, the water-rich filling material has not strength after hydrating for 7 d. When dihydrate gypsum is adequate, the generated ettringite crystals are fine needle-like; but when dihydrate gypsum is inadequate, the generated ettringite crystals are short hexagonal columnar. The strength of the water-rich filling material is mainly derived from ettringite genera-ted by the reaction of sulphoaluminate cement gypsum and lime, rather than the hydration products of cement generated by itself such as hydration calcium sulphoaluminate, alumina gel and calcium hydroxide.%针对富水充填材料的凝结性能受石膏种类影响的问题,采用X射线衍射、扫描电镜、红外光谱等微观实验,分析富水充填材料硬化体的组成,探讨二水石膏和半水石膏对富水充填材料性能影响的机理. 结果表明:以硫铝酸盐水泥-石膏-石灰为主的富水充填材料体系中,为保证正常的凝结硬化,石膏应为二水石膏;如以半水石膏为原材料,在7d龄期时仍不具有强度;二水石膏充足时生成的钙矾石晶体呈细针状,二水石膏不足时生成的钙矾石晶体为六棱短柱状;富水充填材料的强度主要来源于硫铝酸盐水泥-石膏-石灰反应生成的钙矾石,而不是水泥自身水化的水化硫铝酸钙、铝胶和氢氧化钙.

  1. Inorganic Impurity on Preparation of Calcium Carbonate and Its Active Influence Oriented from Desulfurization Gypsum%脱硫石膏中无机杂质对制备碳酸钙及其活性的影响

    史晨杰; 谭文轶; 闫怀晴; 郭霏霏; 徐幸福


    为了达到烟气脱硫石膏减量化处理,建立其资源化利用方法,在考虑到烟气脱硫石膏来源复杂性的基础上,分别考察了金属离子(如Mg2+,Fe3+)和非金属离子(如F-)对利用碳酸铵转化烟气脱硫石膏,制备碳酸钙粉末的影响.结果表明,F-,Mg2+,Fe3+等离子对脱硫石膏转化率有不同程度影响,但转化率均能达到70%以上,转化固体产物为较纯碳酸钙粉末.其中随着阳离子Mg2+,Fe3+含量增加,转化率下降;F-的水解作用以及络合物的生成将对转化率造成复杂影响,0.5wt%为最优的含量.转化产物经其吸收活性测试,其活度比天然石灰石略低,到达脱硫剂基本要求,但需注意杂质离子的积累效应.碳酸铵转化烟气脱硫石膏方法可制备微细碳酸钙粉末,是一种循环利用烟气脱硫石膏的有效途径.%To reduce gypsum produced from wet flue gas desulfurization (WFGD)process and to establish a resource approach to utilize desulfurization gypsum, the effect of metal ion such as Mg2+, Fe3+ and nonmetallic ion such as F" on productivity of calcium carbonate prepared from desulfurization gypsum was investigated, taking into consideration of complex composition of desulfurization gypsum. Results showed that the ions such as F", Mg2+, Fe3+ affect conversion of desulfurization gypsum to different extents, with conversion rate more than 70% and pure calcium carbonate as obtained solid powder. As cationic Mg2+, Fe3+ content increased, the conversion rate decreased. Both hydrolysis of F- and formation of the complicates conversion affected the conversion, with F- 0.5 wt% as the optimal content for conversion. It is verified that the solid product obtained has the potential activity to be recycled as desulfurization absorbent though impurities should be paid attentions. Conversion of desulfurization gypsum to calcium carbonate powder by ammonia carbonate is an effective method to recycle desulfurization gypsum.

  2. Compósitos à base de gesso com resíduos de EVA e vermiculita Gypsum-based composites with EVA waste and vermiculite

    Marilia P. de Oliveira


    Full Text Available O gesso é um dos materiais de construção mais antigos de que se tem conhecimento. Algumas de suas propriedades lhes conferem vantagens, tais como resistência ao fogo e isolamentos térmico e acústico. Objetivou-se, com este trabalho, avaliar as propriedades físico-mecânicas de compósitos à base de gesso com a incorporação de resíduos da indústria de calçados, o etileno acetato de vinila (EVA e a vermiculita. O desenvolvimento desses compósitos tem como propósito a produção de elementos de revestimento para proteção térmica de alvenarias. Para determinar a influência dos teores de resíduo de EVA e vermiculita e da relação água/gesso nas propriedades massa específica aparente e nas resistências a flexão e a compressão, foram incorporados cinco diferentes percentuais desses materiais, combinados com três relações água/gesso. Os resultados foram analisados por meio da estatística multivariável e indicaram que a massa específica aparente de ambos os compósitos e a resistência à flexão do compósito com vermiculita, mostraram maior dependência da relação água/gesso; por sua vez, o percentual de agregado apresentou maior influência na resistência à flexão do compósito com EVA e na resistência a compressão de ambos os compósitos.Gypsum is one of the oldest known building materials. Some of its properties confer advantages such as fire resistance, thermal and acoustic insulation. This work aims to study the physical and mechanical properties of gypsum-based composite with the incorporation of residues from the footwear industry ethylene vinyl acetate (EVA and vermiculite. The aim to develop these composites is to produce components for thermal protection of masonry. To determine the influence of different residue levels of EVA and vermiculite, and the water/plaster ratio on the bulk density, flexural and compressive strength, five different percentages of these materials were incorporated combined with

  3. 磷石膏脱硫钙渣制备轻质碳酸钙%Preparation of light calcium carbonate from phosphorus gypsum desulfurization slag

    时婷; 王新刚; 巫建锋; 杨秀山; 杨林; 王辛龙


    To recycle desulfurization slag from phosphorous gypsum,spherical calcium carbonate was prepared from calcium-containing phosphorus gypsum desulfurization slag. The composition of raw materials were analyzed by XRD and SEM. The main substance was calcium oxide and the main impurity was silica. It also contained a small amount of iron,aluminum and magnesium. A new process leaching desulfurization slag by ammonium chloride and subsequent carbonization was firstly proposed. The affecting factors , such as amount of ammonium chloride , ratio of water and desulfurization slag(mass ratio),and temperature on the performance of leaching were investigated. The optimal conditions were: Amount of ammonium chloride 50% of the total weight of the solid, ratio of water and desulfurization slag 9∶1,temperature 40℃. Conversion of calcium was about 67.98% and removal of silica was 97.80% under the optimal conditions. The purity of the obtained calcium carbonate was 97.90%,sedimentation volume was 3.5mL/g and whiteness was 94.2, meeting the norm of first grade product in(HG/T 2226—2010). Main polymorph of calcium carbonate crystals was vaterite.%为了有效利用磷石膏脱硫钙渣资源,以磷石膏脱硫钙渣为原料合成了球形轻质碳酸钙。本文首先利用XRD 和 SEM 等测试手段分析了磷石膏脱硫钙渣的主要组成是氧化钙,主要杂质为二氧化硅以及少量铁铝镁。在此基础上首次提出了氯化铵浸取磷石膏脱硫钙渣,而后碳化合成轻质碳酸钙的新工艺。探讨了浸取过程中氯化铵的添加量,水与钙渣的液固比(质量比),温度工艺参数对钙浸取率和硅脱除率的影响,确定了较优工艺条件为:氯化铵添加量为总固体质量的50%,水与钙渣的液固比为9∶1,温度为40℃。在该工艺条件下,钙的浸取率可达67.98%,硅的脱除率可达97.80%。对上述浸取液经碳化制备出的轻质碳酸钙,其纯度为97.90%,白度为94.2

  4. 石膏旋流器分离粒度模型建立研究%Study on cut size model establishment in gypsum cyclone

    黄军; 安连锁


    针对火力发电厂WFGD系统中的石膏旋流器,基于旋流器的分离面是零速包络面与溢流管内径所形成的圆柱面的交界面的思想,对各关联公式进行了有效的推演,获取了分离粒度模型,并通过经验优化,建立了综合反映旋流器结构参数、物性参数和操作参数的分离性能的定量描述模型.该模型计算结果与试验结果的相对误差和其他传统经验模型的相对误差相比小0.5%-27.6%.%Aiming at the gypsum cyclone in the WFGD system of thermal power plant, the main idea is that the real separation surface is the interface between the locus of zero vertical velocity (LZVV) and the cylindrical surface forming by the inner diameter of vortex finder. Based on the separation theory, and then we can establish the cut size model by the effective deduction thinking on the relationship formula and practical optimization. The final cut size model which are consist of structure parameters, physical parameters and operating parameters can be set up, this model can describe the separation performance quantificationally. Compare with the test results, the relative error is 0.5%~27. 6% less than the other traditional empirical formula.

  5. 调合消毒法对石膏模型消毒效果的实验研究%Experimental study of disinfection effect of gypsum mixed with disinfectant

    刘嘉; 郑轶文; 李岩; 张晓红; 姜龙; 左恩俊


    To evaluate the effects of disinfection on contaminated gypsum models mixed with disinfectant in vitro. [ Methods] Silicone rubber impressions were divided into the group of Staphylococcus epidermidis, Candida albican-sand and Pseudomonas aeruginosa. The negative control group with no bacterial contamination was set up. Silicone rubber impressions were poured with gypsum power mixed with 2% glutaraldehyde, 0. 5% 84, 0. 5% iodophor and sterile distilled water. One hour later gypsum models were released from silicone rubber impressions. The group of sterile distilled water was positive control group. All specimens were immersed in diluent respectively. Colony forming units were countered after culture and were used to calculate the sterilization ratio. [ Results ] For Staphylococcus epidermidis., Candida albicans and Pseudomonas aeruginosa, 100% reduction of colony forming units was obtained with gypsum mixed with 2% glutaralde-hyde,0. 5% 84 and 0.5% iodophor. [Conclusion] Gypsum mixed with 2% glutaraldehyde, 0. 5% 84,0.5% iodophor can achieve an efficient effect on the gypsum models contaminated by Staphylococcus epidermidis, Candida albicans and Pseudomonas aeruginosa.%[目的]探讨消毒液调拌超硬石膏对沾染微生物石膏模型的消毒效果.[方法]将硅橡胶印模按所染菌种分为表皮葡萄球菌组,白色念珠菌组和绿脓杆菌组.并设立不染菌的阴性对照组.用2%戊二醛、0.5% 84消毒液、0.5%碘伏和无菌蒸馏水调拌超硬石膏,于印模内灌注石膏模型,1h后脱模.无菌蒸馏水调拌组为阳性对照组.将各石膏模型试件浸入稀释液中洗下余菌、接种、培养并进行CFU计数,计算各组的杀菌率.[结果]2%戊二醛、0.5%84消毒液、0.5%碘伏调拌超硬石膏对表皮葡萄球菌、白色念珠菌、绿脓杆菌的杀菌率达100%.[结论]用2%戊二醛、0.5%84消毒液、0.5%碘伏调拌超硬石膏对沾染表皮葡萄球菌、白色念珠菌、绿脓杆菌的石膏模型消毒合格.

  6. 用于外墙内侧、分户墙及顶棚补充节能的轻质石膏砂浆%Lightweight gypsum plaster used on exterior wall, party wall and ceiling for additional energy conservation

    叶蓓红; 施嘉霖; 谈晓青; 曹禹


    轻质石膏砂浆作为粉刷石膏的一个新品种,主要用于墙面的找平层,同时对外墙内侧、分户墙及顶棚具有补充节能的作用.配制时宜选择表面玻化率高、密度小的玻化微珠作为轻骨料,其掺量为石膏量的20%~35%;当采用膨胀珍珠岩作为轻骨料时,其掺量为石膏量的15%~25%;纤维素醚掺量一般为石膏量的0.2%~0.4%;引气剂的掺量为粉料总量的0.6%~1.2%.按m(石膏):m(玻化微珠):m(纤维素醚):m(引气剂):m (SC缓凝剂)=770.0:215.0:4.1:5.0:2.3制备的轻质石膏砂浆导热系数为0.12 W/(m·K),通过计算,采用20 mm厚轻质石膏砂浆代替传统水泥砂浆,对200 mm厚混凝土隔墙进行双面抹灰后,保温效果提高38%.%As a new species of plaster, lightweight gypsum plaster is mainly used for wall leveling layer,meanwhile it has additional energy conservation effect when applied on the inside surface of external wall,party wall and ceiling. During preparation,glass beads with high surface vitrify rate and low density are selected as lightweight aggregate,and its dosage is 20%~35% of the gypsum amount;when expanded perlite is as lightweight aggregate,its dosage is 15%~25% of the gypsum amount;the dosage of cellulose ether is generally 0.22%~0.4% of the gypsum amount;the dosage of air-entraining agent (AEA) is 0.6%~1.2% of the total powder quantity. When m (gypsum) ∶m (glass beads) ∶m (cellulose ethers) ∶m (AEA) ∶m (SC retarder) =770.0∶215.0∶4.1∶5,0∶2.3, the prepared lightweight gypsum plaster has thermal conductivity of 0.12 W/(m·K). The calculation results show that the insulating effect will be increased by 38% if 20 mm-thick this type of plaster instead of the ordinary cement mortar is applied on both sides of the 200 mm-thick concrete wall.

  7. Research on flue gas desulphurization gypsum based inorganic thermal insulation mortar%以脱硫石膏为复合胶凝材料基料配制无机保温砂浆

    孙振平; 郑金飚; 蒋正武; 王君若; 洪辉; 黄晖皓; 杨正宏


    The primary properties and changing law of a kind of inorganic thermal insulation mortar taking Flue Gas Desulphurization gypsum (FCD gypsum) as raw material and small expanded and vitrified balls as lightweight aggregate were studied. The cementitious material made up with FCD gypsum,slag powder,and small amount of cement and activator owned excellent hydration and hardening function,and the 28 d compressive strength can be reached above 25 MPa. The results show that the primary properties of such prepared thermal insulation mortar can meet with the requirements of rlated standards. Moreover,the utilization ability of industrial waste brings them good environmental benefit and social benefit,so the market prospects are broad.%研究了一种以脱硫石膏为复合胶凝材料的基料,以玻化微珠为轻质集料配制而成的保温砂浆的性能及其变化规律.复合胶凝材料由脱硫石膏、矿渣粉、少量水泥和激发剂组成,具备优良的水化硬化特性,其28 d抗压强度能达25 MPa以上.结果表明,以这种复合胶凝材料和玻化微珠共同配制的保温砂浆,其各项性能指标均达到相关标准的要求.同时,因原材料中采用了大量工业废弃物,这种保温砂浆产品的环境效益和社会效益极佳,市场前景广阔.

  8. Incorporação de gesso para correção da salinidade e sodicidade de solos salino-sódicos Incorporation of gypsum to correct the salinity and sodicity of saline-sodic soils

    Antonio N. Tavares Filho


    Full Text Available Com o objetivo de avaliar o efeito da aplicação do gesso nas características químicas de solos salino-sódicos coletados no Perímetro Irrigado do Moxotó, localizado no município de Ibimirim, PE, um experimento foi realizado em colunas de solo instaladas no Laboratório de Mecânica do Solo e Aproveitamento de Resíduo da Universidade Federal Rural de Pernambuco. Os tratamentos foram dispostos em um delineamento inteiramente casualizado com esquema fatorial de dois solos (S1 e S2 e sete níveis da necessidade de gesso (50, 75, 100, 125, 150, 175 e 200% determinado pelo Método de Laboratório Schoonover-M1. O gesso foi incorporado aos solos, em três repetições, totalizando 42 unidades experimentais. As variáveis avaliadas foram: i condutividade elétrica (CE, ii cátions solúveis e iii relação de adsorção de sódio (RAS no extrato de saturação do solo. O nível de 100% da necessidade de gesso causou diminuição da sodicidade para valores de RAS Aiming to evaluate the effect of gypsum on the modification of chemical properties of saline-sodic soils collected in the Irrigated Perimeter of Ibimirim-PE, an experiment was carried out in soil columns installed at the Soil Mechanics and Residue Recovery Laboratoy at the Universidade Federal Rural de Pernambuco. The treatments were arranged in a completely randomized design with factorial arrangement of two soils (S1 and S2 and seven levels of gypsum requirement (50, 75, 100, 125, 150, 175 and 200% determined by the Laboratory Method Schoonover-M1. The gypsum was incorporated in to the soils, in three replications, totaling 42 experimental units. The parameters evaluated were: electrical conductivity (EC, soluble cations and sodium adsorption ratio (SAR in the saturation extract of soil. The level of the 100% of gypsum requirement caused decreased in sodicity values of SAR under 13 (mmol L-1½, presenting itself as an effective method in reducing the levels of sodium in areas affected

  9. 外加剂对脱硫石膏制备现浇墙体材料性能影响%Effect of Additive on Desulfurization Gypsum Cast-in-place Wall Material

    武丽霞; 李冬; 任彦茹


    In order to broaden the usage of desulfurization gypsum, and fulfill the directly use of it, Monosodium glutamate was selected as retarder, poly carboxylic acid was selected as reducing agent, effects of which on desulfurization gypsum cast-in-place wall material were studied. Desul-furization gypsum was prebaked for 2 hours at 55℃, and then burned for 3 hours at 160℃, the standard consistency water demand was determined according to GB/T 17669.4-1999. The experi-ment results were as follows:with adding 3%Monosodium glutamate as retarder, 0.5%Poly carbo-xylic acid as reducing agent, and initial setting time of desulfurization gypsum cast-in-place wall material is about 54 min and final setting time extends to 96 min, which meet the requirements of construction. Dry flexural strength of the wall material is 3.31 MPa, dry compressive strength is 12.27 MPa.%为了拓宽我国脱硫石膏的利用途径,实现对脱硫石膏直接利用,本研究选取谷氨酸钠作为缓凝剂,聚羧酸作为减水剂,对脱硫石膏现浇墙体材料进行改性研究。试验结果表明:电厂的脱硫石膏经过55℃预烘干2 h,160℃烘干3 h,按照GB/T 17669.4-1999确定标稠需水量,添加3%谷氨酸钠作为缓凝剂,0.5%聚羧酸作为减水剂时,现浇墙体材料的初凝时间约54 min,终凝时间延长至96 min,复配后初终凝时间满足施工要求;墙体材料的绝干抗折强度为3.31 MPa,绝干抗压强度为12.27 MPa。

  10. Los depositos de yeso intrasedimentario del arroyo El Siasgo, partidos de Monte y General Paz, provincia de Buenos Aires Intrasedimentary gypsum deposits of El Siasgo Creek, Monte and General Paz districts, Buenos Aires Province

    N. V. Dangavs


    áneas, durante etapas de mayor aridez, sincrónicos con los episodios eólicos del Holoceno temprano y medio. Las determinaciones isotópicas de d34S en yesos de este ambiente, permitieron establecer que estos sulfatos fueron precipitados en una cuenca cerrada (sabkha continental.The El Siasgo Creek is a tributary stream of the Salado River system, located in the north-east part of Buenos Aires province. In its lower basin, the river cuts a great depression, a remnant of an old infilled deflation basin, in which mainly aquatic sedimentary environments have operated from the Upper Pleistocene. At present, this depression represents a 2,750 ha lentic temporary environment, divided in two parts by a 2 km long, 0.7 km wide narrowing of the water basin, to the north, the minor water body named "La Cañada" and to the south the bigger one, "laguna del Siasgo". Important accumulation of intrasedimentary mainly sand-side gypsum are shown in the clastic host sediments of this palaeolentic environment The gypsum crystallized at different stratigraphic levels and with a diversity of habits, textures, fabrics and structures, The host sediment is essentially mud, but the original texture has been modified by this epigenic mineral into sandy muds, sandy silts and muddy sands. The gypsum deposit covers an area of 25,6 km², with 2.15 m mean thickness in "laguna del Siasgo" and 0.91 m in "La Cañada". The total volume of gypsum sediments reaches 48 hm³ with a minimum grade of 53,5% and 53,623,000 tons of impure gypsum , in the bigger water body, whereas in the minor one the mean grade is 20,1% which represents only 1,361,000 tons of impure gypsum. The low gypsum content in "La Cañada" body precludes the posibilities of economic exploitation. However, the "laguna del Siasgo" body has high ecomonic potential, even at its lower mineral content. The genesis of these gypsums are linked to the interaction between surficial and ground waters, during the greater aridity periods of regional eolian

  11. 3种消毒方法对石膏模型表面硬度的影响%Influence of three kinds of disinfection methods on surface hardness of gypsum casts

    曹明国; 吴世莲; 陆林侦; 查光玉


    目的 研究3种消毒方法对口腔石膏模型表面硬度的影响.方法 制作圆柱体金属模具,硅橡胶取模,分别灌注熟石膏、硬石膏和超硬石膏模型,分别用3种消毒方法对其消毒,包括微波加热、高温高压及紫外线照射,消毒后测定其表面硬度,并进行统计分析.结果 微波加热及紫外线照射对3种石膏模型消毒后,表面硬度差异无统计学意义;高温高压消毒处理后的熟石膏组、硬石膏组、超硬石膏组的表面硬度分别为(3.70±0.25)、(4.46±0.30)、(4.93±0.85)Pa,均比对照组明显降低(P<0.01).结论 微波加热及紫外线照射对石膏模型消毒后,在表面硬度方面对模型无明显影响.%OBJECTIVE To study the influence of three kinds of disinfection methods on surface hardness of oral gypsum casts. METHODS The metal cylinder mould and silicone impression was made. Three kinds of gypsum casts including plaster, dental stone, and high strength dental stone were made and disinfected by three kinds of disinfection methods, which were microwave heating, high temperature and pressure and ultraviolet radiation disinfection. After disinfection, the surface hardness was tested and the statistical analysis was performed. RESULTS Disinfection with microwave heating and ultraviolet radiation did not affect the surface hardness of three kinds of gypsum casts, the difference in surface hardness was not statistically significant; the hardness of three kinds of plaster, dental stone, and high strength dental stone after the disinfection with high temperature and pressure were (3. 70 ± 0. 25, 4. 46 ± 0. 30, and 4. 93 ± 0. 85)Pa, with a significant decreases as compared with the control group (P < 0. 01). CONCLUSION Disinfection by microwave heating and ultraviolet radiation has no significant influence on the surface hardness of the gypsum casts.

  12. Optimal Application Rate of Desulfurized Gypsum in Ameliorating Soils Moderate in Sodic Salinity%脱硫石膏改良中度苏打盐渍土施用量的研究

    罗成科; 肖国举; 张峰举; 秦萍


    采用盆栽试验和田间试验相结合的方法,通过种植油葵(Helianthus annus),进行了脱硫石膏施用量的试验.结果表明,施用脱硫石膏能够有效降低土壤碱化度、总碱度和pH值,但却增加了土壤全盐量;施用脱硫石膏可显著提高油葵出苗率和产量,但施用量过高会抑制油葵的生长发育.施用11 250 kg·hm-2脱硫石膏对中度苏打盐渍土改良效果最佳,最有利于油葵的生长发育,耕作层土壤碱化度、总碱度和pH值分别降至6%、0.2 cmol·kg-1和8.5以下,油葵出苗率达到70%以上,田间试验中油葵产量高达2 031 kg·hm-2,与不施脱硫石膏处理相比,增产率达到16.2%.%Both pot experiment and field experiment were carried to test planting of oil sunflower with the application of desulfurized gypsum in ameliorating soils moderate in sodic salinity.Results show that exchangeable sodium percentage (ESP),total alkalinity and pH values decreased significantly,while soil salt content increased.The germination rate and yield of the sunflower increased significantly after desulfurized gypsum was applied,but excessive application of desulfurized gypsum inhibited germination and growth of the plant.After application of 11 250 kg·hm-2 of desulfurized gypsum in the 0-20 cm surface layer of soils moderate in sodic salinity,the chemical properties of the soils improved with ESP reduced down to <6%,total alkalinity to <0.2 cmol·kg-1 and pH to <8.5,and the germination rate increased to over 70% and the yield reached to 2 031 kg·hm-2,or increased by 16.2% in the field experiment.

  13. Structural morphology of gypsum (CaSO 4·2H 2O), brushite (CaHPO 4·2H 2O) and pharmacolite (CaHAsO 4·2H 2O)

    Heijnen, W. M. M.; Hartman, P.


    A uniform description of the crystal structures of gypsum ( CaSO4·2 H2O), brushite ( CaHPO4·2 H2O) and pharmacolite ( CaHAsO4·2 H2O) is presented. From these structures, a PBC analysis leads to the following F forms: {020}, {011}, {⦶1}11 {120} and {⦶1}22 (for brushite and pharmacolite the counterfaces ( ⦶h⦶k⦶l) are included). Attachment energies of the gypsum F faces have been calculated in an electrostatic point charge model for various charge distributions in the water molecule and in the sulphate ion. The theoretical habits are all platy or tabular {020} with {120}, {011} and {⦶1}11, the latter being smaller than {011}, in disagreement with observation. Arguments are given that {011} can grow in layers {built1}/{2}d 011, and therefore faster, at a supersaturation for which {⦶1}11 cannot grow in half layers, thus removing the discrepancy between theory and experiment. The curious triangular or trapeziumlike habit of brushite has been related to its crystal structure. The polar habit is ascribed to different adsorption of water and cosolutes on opposite faces. The most important forms are {020} with {⦶1}20, 11{⦶1} and {111}, the latter being an S form. Its appearance is ascribed to a habit change.

  14. 隧道石膏质围岩溶蚀及溶出特性试验研究%Experimental Research on Corrosion and Leaching Characteristics of Gypsum Rock Surrounding Tunnels

    祝艳波; 吴银亮; 余宏明


    石膏质岩的溶蚀对隧道工程的建设及运营极为不利,研究其溶蚀机理及其影响因素,可为此类隧道的建设提供参考。宜巴高速公路部分隧道通过的地层含有石膏质岩,为了研究其溶蚀及溶出特性,利用X-衍射试验仪、自制简易溶蚀装置、离子色谱分析仪从宏观角度研究其溶蚀、溶出现象及其规律,利用环境扫描电镜从微观上观察其溶蚀机理。结果表明,研究区石膏质岩在地下水的作用下易溶蚀,溶蚀后强度性质变差,同时溶出大量的硫酸根离子于环境水中。影响石膏质岩溶蚀的因素多而复杂,动态水环境将使其溶蚀作用更强烈,并且水流流速越大,溶蚀特征越明显。弱酸性环境的水溶液也会促进溶蚀作用的进行。温度通过影响石膏质岩在水中的溶解度,从而影响其溶蚀量及溶蚀速率。石膏质岩溶蚀后会降低隧道围岩的稳定性,溶出的酸根离子对混凝土衬砌结构产生中等腐蚀,在隧道建设中应注意采取相应防治措施,避免工程病害的发生。%Since the corrosion of gypsum rock has detrimental effects on tunnel construction and operation, the cor⁃rosion mechanism and its influencing factors were studied, providing a reference for tunnel construction in these con⁃ditions. In this paper, the gypsum rock surrounding tunnels on the Yichang-Badong expressway is studied, and a se⁃ries of experiments on the corrosion and leaching characteristics of gypsum rock are carried out to macroscopically study and analyze the law of corrosion and leaching phenomena by using X-ray diffraction tester, self-made corro⁃sion equipment and ion-chromatography analyzer. Additionally, the corrosion mechanism is microscopically ob⁃served with an environmental scanning electron microscope. The research results indicate that the corrosion of gyp⁃sum rock is obvious under the action of underground water and the gypsum

  15. New Treatment Process of Mother Liquor in Vacuum Salt Making with Gypsum Brine%石膏型卤水真空制盐母液处理新工艺



    The treatment process of mother liquor in the 600,000 t/y vacuum salt project of Yulin Salt Chemical Co. CNSIC is introduced. The horizontal spiral centrifuge is adopted to separate the thickened gypsum mother liquor and then the clear liquid is back to the salt making system. The thickened gypsum slurry is to be used as the oringinal material of non-burnt bricks after wash and pressure filtration. The clear liquid after pressure filtration is injected into brine well. This process is an approach to developing circular economy and creating environmental friendly and resource saving enterprise.%介绍了中盐榆林盐化有限公司60万吨/年真空制盐项目的母液处理工艺。首先采用卧螺离心机离心分离增稠制盐石膏母液,离心得到的清液返回制盐系统。增稠后的石膏经洗涤压滤后作免烧砖原料,压滤清液注井采卤。此工艺走出了一条发展循环经济、创建环保节约型企业的道路,取得了非常理想的效果。

  16. Production development and utilization of Zimmer Station wet FGD by-products. Final report. Volume 5, A laboratory greenhouse study conducted in fulfillment of Phase 2, Objective 2 titled. Use of FGD by-product gypsum enriched with magnesium hydroxide as a soil amendment

    Yibirin, H. [Ohio State Univ., Wooster, OH (United States); Stehouwer, R. C. [Ohio State Univ., Wooster, OH (United States); Bigham, J. M. [Ohio State Univ., Wooster, OH (United States); Soto, U. I. [Ohio State Univ., Wooster, OH (United States)


    The Clean Air Act, as revised in 1992, has spurred the development of flue gas desulfurization (FGD) technologies that have resulted in large volumes of wet scrubber sludges. In general, these sludges must be dewatered, chemically treated, and disposed of in landfills. Disposal is an expensive and environmentally questionable process for which suitable alternatives must be found. Wet scrubbing with magnesium (Mg)-enhanced lime has emerged as an efficient, cost effective technology for SO2 removal. When combined with an appropriate oxidation system, the wet scrubber sludge can be used to produce gypsum (CaSO4-2H2O) and magnesium hydroxide [Mg(OH)2] of sufficient purity for beneficial re-use. Product value generally increases with purity of the by-product(s). The pilot plant at the CINERGY Zimmer Station near Cincinnati produces gypsum by products that can be formulated to contain varying amounts of Mg(OH)2. Such materials may have agricultural value as soil conditioners, liming agents and sources of plant nutrients (Ca, Mg, S). This report describes a greenhouse study designed to evaluate by-product gypsum and Mg gypsum from the Zimmer Station pilot plant as amendments for improving the quality of agricultural soils and mine spoils that are currently unproductive because of phytotoxic conditions related to acidity and high levels of toxic dissolved aluminum (Al). In particular, the technical literature contains evidence to suggest that gypsum may be more effective than agricultural limestone in modifying soil chemical conditions below the immediate zone of application. Representative samples of by-product gypsum and Mg(OH)2 from the Zimmer Station were initially characterized. The gypsum was of high chemical purity and consisted of well crystalline, lath-shaped particles of low specific surface area. By contrast, the by-product Mg(OH)2 was a high surface area material (50 m2 g

  17. Gypsum as a source of sulfur for strawberry cropsGesso agricola como fonte de enxofre para a cultura do morango

    Universidade Estadual do Centro-Oeste


    in a randomized block design with three replications, with six doses of S: 0, 10, 20, 30, 40 and 50 mg kg-1 in the form of gypsum, and two doses of P: 300 and 600 mg kg-1 of P2O5. The Albion variety of strawberry plants was transplanted to pots and grown for 170 days. The fruits were harvested and weighed throughout the experiment; a similar procedure was followed for the shoots at the end of the experiment. The shoots and fruits were dried, weighed, ground, and analyzed for the content of S, Ca, and P. The production of strawberry fruits was influenced by S rates, with the highest productivity obtained by using S rates of 60 and 37 mg kg-1 with the application of 300 and 600 mg kg-1 of P, respectively.

  18. Fitorremediação de solo salino s ódico por Atriplex nummularia e gesso de jazida Use of Atriplex nummularia and gypsum for phytoremediation of saline-sodic soil

    Isaac Gomes Leal


    -sodic soil irrigated with saline water was evaluated. Additionally, gypsum was tested for improving phytoremediation. The experiment was set up as a randomized block design, in a 2 x 3 factorial scheme. The treatments consisted of: no gypsum and 50 % of the regularly recommended gypsum dose, and three salinity levels of irrigation water: C1 = 175 μS cm-1; C2 = 500 μS cm-1; C3 = 1,500 μS cm-1. The Na concentration in plant tissues and soil were evaluated 40, 70, 100 and 130 days after A nummularia transplanting. The results showed that there was a 96 % increase in root dry matter as a result of gypsum application. Sodium accumulation in shoots increased significantly in the third (90.1 g kg-1 and fourth (109.7 g kg-1 sampling period. This effect was magnified by gypsum application. After 100 days, the soil Na+ content had decreased by 31 and 26 %, with and without gypsum addition, respectively. Our results indicate that A. Nummularia is a Na+ accumulator species. Gypsum was effective as a phytoextraction enhancer. A. nummularia irrigation aiming at Na phytoremediation is possible with saline water varying from 175 to 1,500 μS cm-1.

  19. 低甲醛脲醛-石膏-膨润土基玉米缓释肥的制备%Preparation of Urea Formaldehyde-Gypsum-Bentonite Based Specialty Slowrelease Fertilizers for Corn

    李娜; 邓跃全; 董发勤; 李丽君; 马春雪


    Based on the compound of urea formaldehyde and gypsum as the binder and compound with bentonite, a slow-release system was got, and the reasonable amount of slow-release nitrogen fertilizer (urea-gypsum), available nitrogen fertilizer (ammonium sulfate), phosphorus fertilizer or potassium fertilizer were added in according to the demand for N, P, K in different growth period of corn. Then through the extrusion mixing reaction, screening and granulation, the integration preparation technology, urea formaldehyde-gypsum-bentonite based specialty slow release nitrogen fertilizer and slow release compound fertilizer for corn were prepared. Fertilizers obtained were coated with polyvinyl formal (PVF) respectively, and corresponding coated fertilizers were got. Using the continuous leaching method, the release rates of N, P, K and S in slow release fertilizers were determined and were compared with conventional compound fertilizer, the results showed that the slow release properties of the fertilizers prepared by the integration preparation technology were better.%  以低甲醛脲醛和石膏的有机-无机复合物为粘结剂,与膨润土复配,形成缓释体系,根据玉米不同生长期对N、P、K的需要,合理配比缓效氮肥(尿素石膏)、速效氮肥(硫酸铵)、磷素肥料或钾素肥料的用量,通过挤压混合反应,振动筛分,圆盘造粒一体化制备技术制备低甲醛脲醛-石膏-膨润土基玉米专用缓释氮肥和缓释复合肥,分别用聚乙烯醇缩甲醛包膜(PVF),获得包膜缓释氮肥和包膜缓释复合肥;利用沙柱连续淋溶法对缓释肥料中N、P、K、S 4种养分的释放速率进行了测定,并与常规复合肥对比,结果表明其缓释性能良好。

  20. 利用原状脱硫石膏制备高强耐水新型建材%Preparation of High-strength and Water-resistant New Buiding Materials by FGD Gypsum

    林海燕; 阳勇福; 郭献军; 王晓峰


    以原状脱硫石膏、拜尔法赤泥、矿渣等为主要原料,水泥熟料作为激发剂,制备高强耐水建筑试块,研究自然养护和75℃高温养护条件下试块的抗压强度及耐水性.结果表明,水泥熟料的加入促进了石膏胶凝材料的水化速度,自然养护和蒸汽养护下,试块都具有较高强度,14d抗压强度均大于20 MPa; 75℃高温养护明显促进了胶凝材料体系的水化进程.石膏胶凝试块软化系数高,耐水性良好;自然养护条件下,随着水泥熟料用量的增加,二次钙矾石生成量增大,软化系数降低,耐水性变差;高温养护早期水化充分,强度较高,且二次钙矾石生成较少,试块软化系数稳定且保持较高水平.%The high strength and water resistant blocks were produced from FGD gypsum,Bayer red mud,slag and cement clinker,and compressive strength and water resistance under the natural conservation and 75 ℃C steam curing condition were studied.The results showed that the gypsum cementitious material hydration speed was promoted when cement clinker was added.Whether natural or steam maintenance,blocks have higher strength,compressive strength of 14 d is above 20 MPa.The cementitious material hydration process is promoted evidently on steam curing condition.The softening coefficient of gypsum cementitious block is high,and water resistance is very good.On natural curing condition,delayed ettringite formation is increasing with the increase of the content of cement clinker,but softening coefficient and water resistance decreases.On steam curing condition,early hydration is very sufficient,and compressive strength is high,the delayed ettringite formation is less,the softening coefficient is high and stable.

  1. 生石膏治疗小儿发高烧114例临床疗效观察%Clinical efficacy observation on treating 114 cases of high fever in children with gypsum



    Objective:To research the clinical effect of gypsum on treating high fever in children. Methods:With contrast treatment method, children with high fever admitted to our hospital were taken 1∶1 in proportion divided into experimental group and control group. The experimental group patients were given gypsum treatment; patients in the control group only received routine nursing. After the experimental period, the patient’s therapeutic effects were compared. Results: The experimental group had 20 cases bring down a fever within 24h, accounted for 35%, bring down a fever within 48h have 36 cases, accounted for 63.1%, bring down a fever after 48h 1 case, accounting for 1.7%, 48h bring down a fever rate was 98.3%. Conclusion: The effect of gypsum on treating high fever in children compared with conventional methods has fewer side effects, worthy of a wide clinical application.%目的:研究生石膏对于小儿高烧病患的临床治疗效果。方法:采用对比治疗的方法,将我院收治的小儿高烧病患按照1∶1的人数比例分为实验组和对照组,对实验组病患给予生石膏治疗,对照组病患仅给予常规护理,实验期结束后,比较两组病患的治疗效果。结果:实验组病患24h以内退烧人数20例,占比35.0%,48h以内退烧人数36例,占比63.1%,48h以后退烧人数1例,占比1.7%,48h退烧率为98.3%。结论:生石膏治疗小儿高烧相较于常规方法效果好,副作用少,经济方便明智的临床推广。

  2. Effect of borax on the hydration process of FGD building gypsum and its mechanism analysis%硼砂对脱硫建筑石膏水化的影响及其机理分析

    夏强; 蒋林华; 仲超; 圣兆兴; 李晓; 张飞军


    As FGD building gypsum has a character of fast solidity. The effect of borax on the hydration process and crystal morphology of dehydrate of FGD building gypsum and relationship between pH value and retarding effect were analyzed. Furthermore, by using the X-ray photoelectron spectroscopy technique, its retarding mechanism was also studied. The results indicate that the addition of borax retards the early hydration of FGD building gypsum, which leads to a delay in the hydration heat evolution. It can also prolong the setting time but has a little influence on strength development. Borax has a better retarding effect in alkaline hydration conditions and the setting time reaches the peak point when pH=10. The addition of borax will lead to the transformation of dihydrate crystal from needlelike to short prismatic. It could cause the large crystal sizes and few links between crystals, in that the strength will be lower. Borax interacts with the Ca element on the crystal nuclei surface of dehydrates and forms a chemical adsorption layer, inhibiting its growth, and consequently slowing down the hydration process.%针对脱硫建筑石膏凝结硬化快的特点,研究了硼砂对脱硫建筑石膏水化进程与二水石膏晶体形貌的影响,以及不同pH值时硼砂的缓凝效果,结合光电子能谱技术对其缓凝机理进行了分析.结果表明,硼砂可以抑制脱硫建筑石膏早期水化,使其水化放热减缓,凝结时间延长,但石膏硬化体强度有所降低;硼砂在碱性的水化条件下对脱硫石膏缓凝效果最佳,在pH值=10时凝结时间出现峰值;硼砂的掺入会改变二水石膏的晶体形貌,使二水石膏形貌由针状变成短柱状,晶体尺寸明显粗化,晶体之间搭接不良,引起强度损失;硼砂与脱硫石膏表面钙元素发生络合作用,在其表面形成化学吸附层,抑制晶核长大,延缓石膏水化进程.

  3. Valorization of apatites and phospho gypsum's residues procured by treatment of wastewater's textile; Valorisation des residus d'apatites et du phosphogypse obtenus apres traitement des eaux textiles

    Rais, Z.; Chaqroune, A.; Madji, M. [Faculte des Sciences Dhar El Mehrez, Lab. de Chimie Physique, Fes (Morocco); Maghnouj, J.; Hassani, E. [Centre de Recherches et d' Etudes des Phosphates, CERPHOS, Casablanca (Morocco); Nejjar, R. [Laboratoire de Controle Qualite CIOR, Fes (Morocco); Kherbeche, A. [Laboratoire de Catalyse et d' Environnement, Fes (Morocco)


    This work concerns the study of different methods of enrichment of apatite and phosphogypsum's residues gotten after treatment of the textile wastewater. The survey based on chemical composition properties, has been directed into three axis. The first one is the utilisation of apatite's residues as secondary constituent into cement whether substituting a part of clinker for an Artificial Portland Cement CPA or a part of limestone for a Portland Cement with Additions CPJ. The second one, is the substitution of the natural gypsum, used by the cement factory, by phosphogypsum's residues as cement's hold up. Finally the mixture of apatite and phosphogypsum's residues in the optimal conditions procured into cement. The results show that the use of apatite's residues and those of the phosphogypsum in cement industry has a good income and improves important physics and mechanical properties by report to the witness cement. (author)

  4. 反应条件对脱硫石膏晶须生长行为的影响%The Effects of Reaction Conditions on Growth Process of Desulphurization Gypsum Whisker

    邓志银; 袁义义; 孙骏; 史培阳; 姜茂发


    以脱硫石膏为原料,采用水热法工艺制备硫酸钙晶须.借助XRD、高分辨显微镜等分析方法,深入探讨了反应温度和反应时间对硫酸钙晶须生长过程的影响.结果表明:利用脱硫石膏可以制备出硫酸钙晶须;随着反应温度的升高和反应时间的延长,硫酸钙晶体的长径比呈先升高后降低的趋势;当反应温度为140℃、反应时间为120min时,长径比达到最大,其值为48.17.%Taking the desulphurization gypsum as raw materials,the calcium sulfate whiskers was prepared by using hydrothermal method. The effects of reaction temperature and reaction time on the growth process of calcium sulfate whisker were studied by the analytical methods,such as XRD and high resolution microscope. The results show that calcium sulfate whiskers can be prepared by using desulphurization gypsum. With the increase of reaction temperature and reaction time,the aspect ratio of calcium sulfate whisker is taken the shape of decreasing trend after first rising. The aspect ratio of calcium sulfate whisker had the maximal value of 48.17 when the reaction temperature was 140℃ and the reaction time was 120min.

  5. Study on Compressive Behavior of Open-cell Aluminum Foam by Gypsum Mould Infiltrating Casting%石膏型渗流法制备的开孔泡沫铝的压缩行为研究

    吴进; 程和法; 黄笑梅; 张燕瑰; 胡志君


    本文采用可溶石膏型预制块,通过加压渗流的方法制备了泡沫纯铝、泡沫ZL101合金和泡沫ZL102合金,并通过准静态压缩实验研究了3种不同基体材料的泡沫铝的压缩行为及吸能性能.结果表明:通过石膏型渗流法制备的开孔泡沫铝合金的孔隙率可以达到85%~93.5%;泡沫铝基体材料的力学性能对泡沫铝压缩力学性能有重要影响;泡沫ZL101合金能够吸收最多的能量,且在较大的应力、应变范围内对材料起到缓冲保护作用.%The polymeric reticular sponge was choosen as the mother plate to make the soluble gypsum mould,and after that, through infiltrating casting to fabricate three kinds of open-cell aluminum foam, which are pure aluminum foam, ZL101 aluminum alloy foam and ZL102 aluminum alloy foam. The compressive behaviors and energy-absorption capacities of those different kinds of foams were investigated by the quasi-static compression test. The experimental results indicate that the porosity of the aluminum foams made by the gypsum mould infiltrating casting are 85%~93. 5%;The matrix properties have notable effects on the mechanical behaviors of foams;The ZL101 aluminum alloy foam can absorb the most energy and also can protect the materials in the larger ranges of stress and strain.

  6. Heat capacities and entropies from 8 to 1000 K of langbeinite (K2Mg2(SO4)3), anhydrite (CaSO4) and of gypsum (CaSO4·2H2O)

    Robie, Richard A.; Russell-Robinson, Susan; Hemingway, Bruce S.


    Heat capacities of K2Mg2(SO4)3 (langbeinite) and CaSO4 (anhydrite) were measured from approximately 8 to 1000 K by combined adiabatic shield calorimetry (8-365 K) and differential scanning calorimetry (350-1000 K). Heat capacities were also measured on natural crystals of gypsum (CaSO4 · 2H2O) between 8.1 and 323.5 K. The molar entropies at 298.15 K, Smo(298.15 K), are 378.8 ± 0.6, 107.4 ± 0.2 and 193.8 ± 0.3 J K−1 mol−1 for langbeinite, anhydrite and gypsum, respectively. The heat capacity in J K−1 mol−1 of langbeinite can be represented by the equation Cp,mo(K2Mg2(SO4)3T) = 535.9 + 0.11011T-1.0200 × 106/T2-4.909 × 10−5T2 -4040.2/T0.5 between 300 and 1000 K with an average deviation of ± 0.4%. For anhydrite the heat capacity between 300 and 1000 K is given by Cp,mo(CaSO4,T) = 372.8 - 0.1574 T +1.695 × 106/T2 + 7.993 × 10−5T2 - 4330.8/T0.5 with an average deviation of ±0.4%.

  7. Gypsum-saturated water to reclaim alluvial saline sodic and sodic soils Água saturada com gesso na recuperação de solos aluviais salino-sódicos e sódicos

    Karien Rodrigues da Silveira


    Full Text Available Inadequate management of soil and irrigation water contribute to soil degradation, particularly in the alluvial areas of Northeast Brazil, where salinity and sodicity are already common features. This study evaluates the effects of the addition of gypsum in the irrigation water on physical and chemical properties of soils with different levels of salinity and sodicity. Samples were collected at the Custódia irrigation area of Brazil, predominantly covered by alluvial soils. Leaching tests using simulated irrigation water classified as C3S1, and gypsum-saturated irrigation water were carried out in soil columns of 20 and 50 cm depth. Soil leaching with gypsum saturated water (T2 resulted in an increase in the amounts of exchangeable calcium and potassium, and in a decrease of soil pH, in relation to the original soil (T0, with significant statistical differences to the treatment using only water (T1. There was a reduction in the electrical conductivity, exchangeable sodium and exchangeable sodium percentage in both treatments (T1 and T2, with treatment T2 being more effective in the leaching of soil sodium. No changes of electrical conductivity, calcium and pH in depth were observed, but the 20 - 50 cm layer presented higher amounts of magnesium, sodium and exchangeable sodium percentage. Gypsum saturated water improved the hydraulic conductivity in both layers. The use of gypsum in the irrigation water improved soil physical and chemical properties and should be considered as an alternative in the process of reclamation of saline-sodic and sodic soils in Northeast Brazil.O manejo inadequado do solo e da água de irrigação contribui para a degradação dos solos, particularmente nas áreas aluviais do Nordeste do Brasil, onde a salinidade e a sodicidade são características comumente observadas. Avaliaram-se os efeitos da adição do gesso na água de irrigação, sobre as propriedades físicas e químicas de solos com diferentes níveis de

  8. Gypsum application in the soybeans no-tillage system with and without potassium fertilization. = Gessagem na cultura da soja no sistema de plantio direto com e sem adubação potássica

    Leandro Rosatto Moda


    Full Text Available The gypsum can be used as a sulfur source, thereby improving nutrition and promoting gains in yield of soybeans in no-tillage system. The objective of this study was to evaluate the effects of sulfur applied as gypsum in the soybean culture under the no-tillage system with and without potassium fertilization. The experiment was conducted in the city of Guaíra-SP in an OXISOL. The experimental design used was randomized blocks in factorial scheme 2 x 5 with four replications. The treatments were obtained by combining two levels of K (0 and 60 kg ha-1 K2O, applied as potassium chloride, and five doses of sulfur (0, 30, 60, 90 and 120 kg ha-1 S applied in the form of gypsum. Foliar potassium, calcium and sulfur, in addition to grain yield and oil content in the grains were evaluated. It was observed that the application of sulfur in the soil improved the nutritional status of soybean in potassium, calcium and sulfur, without affecting grain yield, independent of potassium fertilization. The presenceof sulfur in the soil increased the oil content in soybean grain with or without potassium fertilization. = O gesso agrícola pode ser utilizado como fonte de enxofre, desta forma, melhorando a nutrição e promovendo ganhos na produtividade da cultura da soja em sistema de plantio direto. Objetivou-se com este trabalho avaliar os efeitosdo enxofre (S aplicados na forma de gesso agrícola na cultura da soja em sistema de plantio direto com e sem adubação potássica. O experimento foi conduzido no município de Guairá-SP em solo da classe LATOSSOLO VERMELHO Eutrófico. O delineamento experimental utilizado foi o de blocos ao acaso, em esquema fatorial 2 x 5, com quatro repetições. Os tratamentos foram obtidos pela combinação de dois níveis de K (0 e 60 kg ha-1 de K2O, fonte cloreto de potássio; e cinco doses de enxofre (0, 30, 60, 90 e 120 kg ha-1 de S, fonte gesso agrícola. Foram avaliados os teores foliares de potássio, cálcio e enxofre, al

  9. Solo sódico tratado com gesso agrícola, composto de lixo urbano e vinhaça Sodic soil treated with agricultural gypsum, urban waste compost and vinasse

    Maria de F. G. dos Santos


    Full Text Available O manejo inadequado da água de irrigação tem causado problemas de salinidade e sodicidade do solo nos perímetros irrigados com redução significativa na produtividade das culturas. Objetivando-se avaliar os efeitos da necessidade do gesso (NG: 0 e 40%, do composto de lixo urbano (CLU: 0 e 20 t ha-1 e do período de incubação com vinhaça: 15, 30, 45 e 60 dias, sobre a recuperação de um solo sódico do projeto de irrigação São Gonçalo, no Estado da Paraíba, conduziu-se um experimento em casa-de-vegetação, do CCA/UFPB. Usou-se o delineamento em blocos ao acaso em esquema fatorial: 2 x 2 x 4, com três repetições e o algodoeiro herbáceo, cultivar CNPA-7H, como cultura teste. O gesso + CLU aumentou a percentagem de emergência (%E, a biomassa seca (BS e o Ca2+ e diminuiu os teores de Na+ e o pH nos lixiviados, em relação ao solo incubado com vinhaça, enquanto o Ca2+ aumentou com a NG mas diminuiu com o CLU. Para os períodos de incubação ocorreu redução linear nos teores de Na+ na presença da NG e do CLU, isolados, e quando associados constatou-se redução também do Ca2+ e da condutividade elétrica (CE em efeitos quadráticos e aumento do pH. A incubação do solo apenas com vinhaça concorreu para aumentar a %E e a CE em efeitos quadráticos e reduzir, de forma linear, a BS e o Ca2+.The inadequate management of the irrigation water have caused salinity and sodicity problems in the irrigated perimeters with significant reduction of crop yields. This research was carried out in a greenhouse of CCA/UFPB, with the objective of studying the effects of necessity of the gypsum (NG: 0 and 40%, urban waste compost (CLU: 0 and 20 t ha-1 and periods of incubation with vinasse: 15, 30, 45 and 60 days, on the reclamation of a sodic soil, from the "São Gonçalo Irrigation Project", in the State of Paraiba, Brazil. The experiment was conducted in randomized block design in a 2 x 2 x 4 factorial scheme, with three repetitions and

  10. Effect of Impurities on Conversion of Gypsum and Crystallization of Calcium Carbonate%杂质对磷石膏与碳酸铵反应及产物碳酸钙结晶的影响

    丁光月; 李岳; 樊彩梅; 荆宏健; 冯军强


    用碳酸铵与磷石膏反应制取硫酸铵是磷石膏利用的有效途径之一,但磷石膏中的杂质会对石膏的转化过程及碳酸钙的结晶产生不利影响,进而影响碳酸钙的分离过程.以二水硫酸钙与碳酸铵为原料,以磷酸、硝酸镁、氟化钠及酸不溶物(AI)为杂质添加剂,研究了磷石膏复分解反应制取硫酸铵过程中杂质P2O5、Mg2+、F-及AI对硫酸钙转化率的影响,并对反应产物碳酸钙的结晶形态和晶型进行了SEM和XRD分析.结果表明,杂质的存在不仅降低了石膏中硫的转化率,而且使碳酸钙的晶型和晶体形状发生了变化,从而将影响产物的物性和过滤性能.%An effective approach of phosphogypsum utilization is the production of ammonium sulfate from ammonium carbonate and phosphogypsum. However, impurities in phosphogypsum have a negative impact on gypsum transformation process and the crystallization of calcium carbonate , and thus on the separation process of calcium carbonate. In this paper, calcium sulfate dihydrate and ammonium carbonate were used as raw materials, with phosphoric acid, magnesium nitrate, sodium fluoride and acid-insoluble material(AI) as impurity additives, to investigate the effects of the impurities P, Mg2+ , F- and AI on the conversion of calcium sulfate. The crystal line state and morphology of the product calcium carbonate were characterized by SEM and XRD analysis. The results show that the impurities not only affected the conversion of sulfur in gypsum, but also changed the type and shape of calcium carbonate crystal, consequently, affected the physical properties and filtration performance of products.

  11. Alterações físico-químicas e movimentação de íons em Latossolo gibbsítico sob doses de gesso Physico-chemical attributes and ion leaching in a Gibbsitic Latosol as affected by gypsum

    Milson Evaldo Serafim


    Full Text Available Com o objetivo de avaliar o efeito de doses de gesso no ponto de carga zero estimado (PCZ, na dinâmica do cálcio, magnésio, potássio e sulfato, e na retenção de água de um Latossolo Vermelho distroférrico gibbsítico, textura muito argilosa, realizou-se experimento em vasos, em casa de vegetação. Foram estudadas seis doses de gesso agrícola (correspondentes a 0, 3, 6, 9, 12 e 15 Mg ha-1 e duas condições de fornecimento de água, "sem veranico" e "com veranico" para a soja cultivada. Na coleta de solo para o experimento foram consideradas as camadas 0-0,2 m e 0,7-0,9 m representando os horizontes A e Bw respectivamente. Foram montados vasos com a sobreposição de dois tubos de PVC de 0,2 m de comprimento e 0,1 m de diâmetro interno, formando duas camadas: a superior, com material do horizonte A, corrigido com calcário dolomítico, e a inferior, com material do horizonte Bw, sem correção do pH; ambas na densidade de 1 kg dm-3. O PCZ foi alterado em função das doses de gesso. Houve aumento dos teores de Ca, também em resposta as doses de gesso. Não houve diferença nos teores de S na camada superficial, mas houve aumento na camada subsuperficial em resposta à dose de gesso. Constatou-se redução nos teores de Mg na camada superficial e elevação na camada subsuperficial, com o aumento das doses de gesso. Não houve variação nos teores de K e na retenção de água para as diferentes doses de gesso e regime de fornecimento de água.The effect of gypsum on the point of zero charge-PZC, calcium, magnesium, potassium and sulfate dynamics, and water retention were evaluated in a very clayey dystrophic gibbsitic Red Latosol. Six doses of gypsum (corresponding to 0, 3, 6, 9, 12 and 15 Mg ha-1 and two water supply conditions (with and without water deficit were imposed to soybean crop. Soil was sampled at the depths of 0-0.2 m and 0.7-0.9 m, representing the A and Bw horizons, respectively. Soil samples were placed in PVC tubes

  12. Pcm inclusion in gypsum boards for thermal energy storage through latent heat: thermal characterization with DSC; Incorporacion de materiales de cambio de fase en placas de yeso para almacenamiento de energia termica mediante calor latente: caracterizacion termica del material mediante la tecnica DSC

    Oliver, A.; Neila, F. J.; Garcia, A.


    Differential Scanning Calorimetry (DSC) is a thermal analysis technique which has been used for more than three decades to measure the temperatures and heat flows associated with transitions in materials as a function of time. Other techniques, are Differential Thermal Analysis DTA and Conventional Calorimetry. There is great uncertainty in the values supplied by the manufacturers (because they are referred to pure substances) and the DSC should be used to get more accurate values. It will be analyzed the thermal storage capacity depending on temperature for several compound materials formed by some aggregates, mainly gypsum and phase change materials, in various proportions. The results have been compared with other building materials such as gypsum boards and brick layer. The suitability of the new construction material for thermal energy storage will be assessed in comparison with other materials traditionally used for this purpose. (Author) 21 refs.

  13. Available phosphorus and sulphur, exchangeable aluminum and remaining phosphorus in rhodic eutrudox submitted to gypsum cultivated with wheat and soybean Fósforo e enxofre disponível, alumínio trocável e fósforo remanescente em latossolo vermelho submetido ao gesso cultivado com trigo e soja

    Leandro Rampim


    Full Text Available The response to gypsum as a supplier of nutrients in the subsurface provides better root distribution for annual crops plants and thus provides use of larger volume of soil increasing the uptake of water and nutrients and therefore increased productivity, especially with evidence of interference of gypsum in phosphorus available in the soil. In this study evaluated the use of gypsum (CaSO4.2H2O the levels of available phosphorus and sulfur, exchangeable aluminum and interference in the remaining phosphorus in the soil at 0-0.10, 0.10-0.20; 0.20-0.40 m of deep in Rhodic Eutrudox in no tillage and crop yields of wheat and soybean. We conducted sampling of soil at six and 12 months after surface application of 1000, 2000, 3000, 4000 and 5000 kg ha-1 gypsum and treatment without application of gypsum. The use of gypsum increased linearly the S content is available in layers from 0-0,10, 0,10-0,20 and 0,20 to 0,40 m deep, with the minimum content of available P at a dose of 2200 kg ha-1 and exchangeable Al with a dose of 3000 kg ha-1 layers evaluated, however, did not influence the values of remaining P. The use of gypsum increased linearly the S content available at depths of 0-0.10, 0.10-0.20 and 0.20-0.40 m, minimum P content available at the dose of 3166 kg ha-1 and exchangeable Al minimum point at the dose of 3300 kg ha-1 at a depth of 0.20-0.40 m however, did not affect the remaining P values. The use of gypsum increased the productivity of wheat, but did not influence soybean yield. A resposta ao gesso agrícola como fornecedor de nutrientes na subsuperfície proporciona melhor distribuição de raízes para culturas anuais e assim propicia às plantas explorar maior volume de solo aumentando a absorção de água e nutrientes e consequentemente incrementar a produtividade, com indícios da interferência do gesso no teor de fósforo disponível no solo. Neste trabalho o objetivo foi avaliar o uso do gesso agrícola (CaSO4.2H2O nos teores de f

  14. Efeito da aplicação de efluente da fábrica de celulose junto com fosfogesso na correção da acidez do solo Cellulose mill liquid alkaline waste and gypsum as a substitute for lime in soils

    T. Kinjo


    Full Text Available Foram coletados vários efluentes alcalinos da fábrica de celulose a fim de estudar a utilização destes junto com fosfogesso na correção da acidez do solo. Avaliou-se o poder de neutralização dos efluentes e a lixiviação de sódio na presença de fosfogesso numa coluna de terra. A aplicação do efluente eleva o pH do solo e o volume de efluente necessário para atingir pH 6,5 depende da sua composição química e o poder tampão de acidez do solo. A lixiviação de sódio é maior quando o fosfogesso é incorporado ao solo. A combinação do efluente com o fosfogesso corrige a acidez do solo, aumenta o teor de cálcio e, ao mesmo tempo, reduz o acúmulo de sódio no solo.Alkaline liquid effluent from cellulose factories was used in an experimental study to appraise the feasibility of utilizing this material with industrial gypsum (residual material from superphosphate production for the correction of soil acidity. A soil + gypsum column was prepared and leached with the sodium rich industrial waste. Soil pH was raised but the amont of material needed bring it to 6.5 was found to vary with soil chemical composition and soil acidity buffering capacity. The soil leachate was richer in Na when gypsum was presented. Results obtained show that industrial gypsum combined with alkaline waste neutralizes soil acidity, increases soil calcium content and prevents sodium accumulation in the soil.

  15. 施用烟气石膏和灌溉对土壤盐分和油葵产量的影响%Effects of application of gypsum from flue gas desulphurization and irrigation on soil salt contents and oil sunflower yields

    樊丽琴; 杨建国; 许兴; 孙兆军; 尚红莺


    This field experiment studied the effects of flue gas desulphurization by-product gypsum and irrigation on soil salt content and oil sunflower yield. The results showed that the treatment with 10 t flue gas desulphurization byproduct gypsum per hm2 and 3 900 m3 water per hm"2 had best desalination effect, and the desalination rate of upper layer of soil increased with increased irrigation amount. Under the conditions of application of 10 t flue gas desulphurization by-product gypsum per hm2 and 3 900 m3 per hm"2 of irrigation amount, soil salt content in the soil was the lowest, and germination rate and yield of oil sunflower were the highest.%本研究通过田间试验探讨不同灌水量、不同烟气石膏用量对土壤盐分和油葵产量的影响.结果表明:烟气石膏施用量为10t?hm-2时,土壤脱盐效果最好,较高的灌水量处理上层土壤脱盐率较高.当灌水量为3 900 m3?hm-2、烟气石膏施用量为10 t?hm-2时,土壤耕层盐分最低,油葵出苗率和产量最高.

  16. Recovery Technology Program of the Lean Mine Resources in the Goaf of Yuquan Mining Area in Xishan Gypsum Mine%西山石膏矿玉泉矿区采空区贫矿回收技术改造方案



    西山石膏矿在过去采用房柱法开采过程中对采空区内的贫矿没有进行回收,造成了资源的浪费。通过技术改造,设计采用后退式回采方法,采用底板回采爆破、矿柱回采爆破、崩柱切顶爆破和矿石回收等技术,回收利用玉泉矿区的贫矿资源,变废为宝,提高资源回采率,保护环境,具有良好的经济和社会效益。%Room-and-pillar method which used in Xishan gypsum mine caused the waste of gypsum resources in the goaf. We designed to using the retreating stoping method to recover the lean mine resources. Stoping and blasting with the ore lfoor and the pillar, collapsing the pillar and cutting the roof, recover the lean gypsum resources of Yuquan mining area, make waste proiftable, improve the resources utilization rate, protect the environment and has a good economic and social beneifts.

  17. 艺术铸造领域CNC机器人七轴加工设备用于石膏模型雕塑%Application of CNC Robot Seven-axle Working Equipment to Carving Gypsum Mold in Art Casting Field



    CNC robot seven-axle working equipment consists of a power-driven main shaft controlled by the robot, an automatic programming software and a software used for controlling manipulator operation, and makes it possible to realize automatic carving of a complex stereometric moulding. The special equipment used in carving gypsum mould by the CNC robot seven-axle working equipment allow large-scale sculpture templating technology to obtain signiifcant progress.%CNC机器人七轴加工设备由一个工业机器人控制电动主轴、多轴自动编程软件和用于控制机械手运行的软件组合而成,可实现复杂立体造型的自动化雕刻加工。CNC机器人七轴加工雕塑石膏模型专用设备,实现了艺术铸造大型雕塑放样的一大跨越。

  18. Early age hydration of calcium sulfoaluminate (synthetic ye'elimite, C{sub 4}A{sub 3}S{sup ¯}) in the presence of gypsum and varying amounts of calcium hydroxide

    Hargis, Craig W. [Department of Civil and Environmental Engineering, University of California, Berkeley, CA (United States); Kirchheim, Ana Paula [Department of Civil Engineering, Federal University of Rio Grande do Sul, Porto Alegre, RS (Brazil); Monteiro, Paulo J.M., E-mail: [Department of Civil and Environmental Engineering, University of California, Berkeley, CA (United States); Gartner, Ellis M. [Lafarge Centre de Recherche, St. Quentin Fallavier, Isere (France)


    Suspensions of synthetic ye'elimite (C{sub 4}A{sub 3}S{sup ¯}) in a saturated gypsum (CS{sup ¯}H{sub 2}) and calcium hydroxide (CH) solution were examined in-situ in a wet cell by soft X-ray transmission microscopy and ex-situ by scanning electron microscopy. The most voluminous hydration product observed was ettringite. Ettringite commonly displayed acicular, filiform, reticulated, and stellate crystal habits. Additionally, pastes with C{sub 4}A{sub 3}S{sup ¯}, 15% CS{sup ¯}H{sub 2}, and varying amounts of CH were prepared and examined with X-ray diffraction (XRD) and isothermal calorimetry. The XRD experiments showed that increasing CH content caused more solid solution (SO{sub 4}{sup 2−}/OH{sup −}) AFm phases to form at early ages (< 1 d) and more monosulfate to form at later ages (> 1 d). Calorimetry indicated that the increased production of solid solution AFm was accompanied with an increase in the initial (< 30 min) rate of heat evolution, and increasing CH generally reduced the time till the second maximum rate of heat evolution due to the formation of ettringite and monosulfate.

  19. 泥浆雾化电感耦合等离子体光谱法用于水泥和石膏的分析%Slurry Nebulization for the Analysis of Gypsum and Cement by Inductively Coupled Plasma Spectrometry

    RobertIMccrindle; LjiljanaMarjanovic


    本文详细地论述了用泥浆雾化电感耦合等离子光谱法分析水泥和石膏.%The usual form of presentation for a sample to be analyzed by an inductively coupled plasma-optical emission spectrometer is in the form of a liquid.For the analysis of solids,this involves a dissolution step and in the case of complex matrices this may be long and difficult.Should it be possible to analyse the sample without prior dissolution, then the problems associated with obtaining a solution would be resolved.A method for analyzing samples is to make use of slurry nebulization.Samples with complex matrices, such as cement and gypsum were selected and analysed as in the form of a slurry.Using different concentrations of slurry of a certified reference materials,calibration curves were obtained,from which the unknown samples could be determined directly.Use of aqueous solutions for calibration was also investigated.The method was evaluated using other reference materials or results obtained by an independent laboratory using different technique for the analysis.The slurry method was found to be accurate and precise.

  20. 原状脱硫石膏泡沫混凝土的制备与性能研究%Preparation and Performance of Undisturbed Desulfurization Gypsum-based Foamed Concrete

    雷东移; 郭丽萍; 孙伟


    原状脱硫石膏泡沫混凝土是在自主研发的原状脱硫石膏高强胶凝材料体系的基础上,以 H2 O2为化学发泡剂,同时在催化剂 MnO2的作用下,利用反应后产生的 O2达到自主发泡的目的,并掺入一定量的聚丙烯纤维和稳泡剂硬脂酸钙分别起到增强增韧和稳定气泡的作用。实验研究了不同组分对原状脱硫石膏泡沫混凝土各项性能的影响,包括干密度、抗压强度、导热系数、气孔率、线性收缩率、吸水率等性能,并利用扫描电子显微镜观察了不同发泡剂掺量时孔结构的微观形貌,最终确定了最佳配合比:胶凝材料体系组分为1(所包含组分质量比为:m(原状脱硫石膏)∶m(矿渣)∶m(水泥)∶m(石灰粉)∶m(水玻璃)∶m(减水剂)=60∶31∶9∶6∶0.7∶1.8),发泡剂掺量为2.5%、硬脂酸钙为3.2%、纤维为0.15%、水胶比为0.38,均外掺(质量比)。原状脱硫石膏泡沫混凝土各项性能均满足标准JC/T 266-2011《泡沫混凝土》的相关要求。本研究大大扩大了工业废石膏的应用范围,有效节约了自然资源,具有重要的社会现实意义。%Based on the self-developed undisturbed desulfurization gypsum-based high-strength cementitious material,undisturbed desulfurization gypsum-based foamed concrete was prepared using H2 O2 as chemical foaming agent,MnO2 as catalyst.O2 was produced from the decomposition of H2 O2 which contributed to self-foaming,and a certain amount of polypropylene fibers and foam stabilizer calcium stearate were incorporated,in order to improve toughness and stabilize bubbles,respectively.The influence of different components on the various performances of foamed concrete,including dry density,compressive strength,thermal conductivity,porosity,linear shrinkage,water absorption,pore structure,were studied in this paper.The pore structure of foamed concrete on different content of foaming agent was observed by SEM.As a result,the optimum mix

  1. 磷高强石膏-粉煤灰-石灰的耐水性研究%Study on Water Resistance of Phosphogypsum Based on High Strength Gypsum-Fly Ash-Lime Materials

    茹晓红; 汤琦; 马保国; 邹开波


    将粉煤灰及其激发剂石灰加入到磷石膏制备的高强石膏中制备出水硬性的磷石膏粉煤灰石灰( PGFL)复合胶凝材料。通过对比试验研究了石灰、粉煤灰、磷高强石膏(PGHH)掺量对产品软化系数、抗压强度性能的影响,结果表明:加入适量的粉煤灰、石灰可以显著提高PGFL的后期绝干抗压强度和软化系数,提高材料的耐水性,掺量过多则会带来不利影响。%Phosphogypsum-fly ash-lime cementitous materials ( PGFL) was prepared by phosphogypsum based high strength hemihydrate gypsum ( PGHH) mixed with fly ash and lime. Effects of lime, fly ash and PGHH additions to PGFL properties of compressive strength and softening coefficient were investigated through comparison testing. The results showed that water resistance of PGFL material was improved by long-term dry compressive strength and softening coefficient increased significantly with proper fly ash and lime contents. However, adverse impacts may caused by too much fly ash and lime additions.

  2. Development of materials that cover the deposits of gypsum exploited in the polo plasterer in Pernambuco; Aproveitamento dos materiais que recobrem as jazidas de gipsita explotadas no polo gesseiro de Pernambuco

    Rego, S.A.B.C.; Moraes, A.S. de; Anjos, I.F. dos, E-mail: [Universidade Federal de Pernambuco (UFPE), PE (Brazil); Lira, B.B. [Universidade Federal da Paraiba (UFPB), PB (Brazil)


    The mineral clay found on the surface of gypsum deposits in the region of Recife - PE are considered mining tailings and job search reference in new industrial applications for these minerals, ores. In this context, we performed the characterization of these materials with the purpose of its use as inorganic pigments in the ceramic coating. These minerals present 'in locus' different colors ranging from beige to reddish. After heat treatment at 1000° C their colors have varied tones that can be used as natural pigments in the ceramic industry. The techniques of fluorescence X-ray diffraction X-ray, infrared and colorimetry were applied in the characterization of mineral-ore in question. Using mineral processing techniques we obtain a physical separation of clay minerals associated. The use of concentrated after processing showed that the material has the potential to replace traditional pigments used in ceramic industry, and thus represent a new alternative on the market of natural pigments. Another potential comprehensive analysis of the material is its use associated with polymers in order to develop new materials. (author)

  3. Experimental study on the influence of emulsion powder on strength of thermal insulation material of FGD gypsum-based%乳胶粉对脱硫石膏基保温板强度影响的试验研究

    于秋仙; 薛力梨; 王启湘; 杨金根; 孙溪禧; 袁波


    将火力发电产生的脱硫石膏和粉煤灰两大废弃物,与泡沫玻璃边角料、玻化微珠等保温材料以及外加剂等复合制备保温板,研究其力学性能,并分析其应用前景。结果表明:制得的保温板抗压强度最高可达0.76MPa,干表观密度均在500kg/m3左右。%Two waste generated by the thermal power, desulphurization gypsum and fly ash, compound with foam glass scrap, vitrified micro bead thermal insulation materials and additives to execute Thermal insulation board,to study the mechanical properties and thermal properties, and the application prospect is analyzed. Results show that the heat preservation plate compressive strength more than 0.76 MPa, dry table view the minimum density are all about 500 kg/m3.

  4. A New Topology Structure of Gypsum Embedded Filler Flat Plate Floor and Its Static Analysis%一种新型石膏空腔模无梁楼盖拓扑结构及静力分析



    Gypsum embedded filler flat plate floor,which uses precast gypsum embedded fillers as permanent formworks, is a monolithic cast-in-situ hollow concrete floor system.There are five kinds of structures.They are waffle slab,composite open-web floor,composite cross-beam and open-web floor,cross-beam floor,and nine-rectangle-grid floor.According to topology optimization of solid floor structure of two or three spans by ANSYS,72 false density distributions have been ob-tained.On the basis of the above results,a new structural model with composite hidden-prop-cap and cantilever-three-rib floor can be designed.Through the static analysis under vertical load by ANSYS,deflection and stress distribution of com-posite hidden-prop-cap and cantilever-three-rib floor are studied in detail.The results show that the stress of composite hid-den-prop-cap and cantilever-three-rib floor does not take on obvious characteristics of solid floor.So its strength of concrete and reinforcement does not been fully used and its reinforcement design will be complex.However,the composite hidden-prop-cap and cantilever-three-rib floor is suitable for those buildings which large span and whose floors under big loads be-cause of the less consumptions of concrete,good vertical rigidity and small peak tensile stress.%石膏空腔模无梁楼盖是以预制石膏空腔模为永久性施工内模的整体现浇空心楼盖,有密肋式、空腹板架式、井字-空腹板架组合式、井式、9区格式五种结构。用 ANSYS 对不同情况下的双跨、三跨楼盖做拓扑优化,得到72张单元伪密度云图并归纳伪密度分布规律,在此基础上设计一种新型结构———暗柱帽-悬挑三肋楼盖。用 AN-SYS 对暗柱帽-悬挑三肋楼盖做竖向荷载作用下的静力特性理论分析,详细研究其挠度和正应力分布。研究表明:暗柱帽-悬挑三肋楼盖的正应力分布不呈实体板特征,不利于发挥材料强度和配筋设计;

  5. 脱硫石膏基胶凝材料用于保温墙体的探糾%Exploration of desulfurization gypsum cementitious materials used for thermal insulation wall

    孔文栋; 薛力梨; 李强; 潘佳林


    将火力发电厂产生的脱硫石膏,粉煤灰两大废弃物以及另一种废弃物粉煤灰以一定比例混合制成胶凝材料,并与废弃的泡沫玻璃边角料复合制备成保温板,研究其强度、导热系数和表观密度等性能,并分析应用前景。结果表明:制得的保温板抗压强度在1.8MPa以上,导热系数在0.12-0.14w/(m.k)之间,干表观密度最小可以达到900kg/m3.。制得保温板成本低廉、保温性好,应具有良好的应用前景。%The coal-fired power plant desulfurization gypsum, two large waste, fly ash, and another kind of waste, to a certain proportion of fly ash to make cement materials and waste foam glass compound preparation into insulation board, examines the strength, thermal conductivity and apparent density, such as performance, and study its market prospects. Experiments prove that the compressive strength of insulation board above 1.8 MPa, the coefficient of thermal conductivity between 0.12 to 0.14 W/(m.k), dry apparent density minimum can reach 900 kg/m3.Because of new thermal insulation wall materials manufacture simple, low cost, good heat preservation, should have a good application prospect.

  6. 脱硫石膏改良滨海盐碱土的脱盐过程与效果实验研究%The experimental study on the process and effect to the FGD-gypsum as an improvement in coastal saline-alkali soil

    程镜润; 陈小华; 刘振鸿; 李小平; 付融冰; 陈泉源


    针对上海滨海盐碱土的特点,借助土柱淋洗试验方法,研究了脱硫石膏改良滨海盐碱土的脱盐过程与效果,分析了不同石膏质量配比条件下(0%,1%,2.5%,5%和10%),土壤团粒结构和水力传导度变化以及盐碱土-脱硫石膏体系中的离子交换过程与效率.研究结果表明:加入脱硫石膏之后,盐碱土团粒结构得到改善,孔隙度变大,水力传导能力增强,平均导水系数是对照组的4~5倍,有效加快脱盐过程;在土柱开始淋洗的前6d 内,离子交换过程表现最活跃,淋洗液的电导率和离子浓度急剧下降.添加脱硫石膏的土柱中钙离子优先置换出钠离子,平均脱钠效率达到对照组的1.8倍.钙钾离子交换和钙镁离子交换也同步发生,但规模明显小于钙钠离子交换.当脱硫石膏质量配比超过1%时,盐碱土的脱盐效果主要取决于原土中的交换性阳离子总量.随着配比增加,盐碱土脱盐的边际效益增加量并不显著.在充分混匀的理想条件下,建议上海滨海盐碱土改良过程中添加脱硫石膏的质量配比高于1%为宜.%Studied the process and efficiency of desalination in FGD-gypsum as an improvement in coastal saline-alkali soil, analyzed the changes of soil’s aggregation and Hydraulic conductivity, and ion exchange process and effect of soil-gypsum system under different gypsum proportions (0%, 1%, 2.5%, 5%, and 10%) with the testing method of leaching aimed at characteristics of coastal saline-alkali soil in Shanghai. The result showed that soil aggregation has improved obviously, porosity has increased, soil hydraulic conductivity has enhanced, the average water diffusivity of soil was 4-5times than the control and sped the process of desalination effectively;ion exchange exhibited actively and the conductivity of eluent fell sharply as same as the concentration of ions in the beginning of 6days. Calcium ions exchanged sodium ions first in experimental groups, the

  7. 肥料与石膏配施对滨海盐土玉米生长及养分吸收的影响%Effects of Fertilizer with Gypsum Application on Growing Development and Nutrient Uptake of Potting Corn in Coastal Saline Soil

    李孝良; 徐克琴; 肖瑞; 李健姣; 陈效民; 王晓洋


    The effects of fertilizer with gypsum with the pot experiments in coastal saline soil application on growing development and nutrients uptake of corn were studied. The appropriate fertilizer varieties were discussed. The results were as follows: there were significant effects in fertilizer and gypsum application on corn growth in coastal saline soil. The dry matter accumulation and nutrient uptake in the treatment of gypsum with organic - in- organic fertilizer or bio - organic fertilizer and inorganic compound fertilizer were better. During corn growth periand among the tested fertilizer varieties, the order of the dry matter accumulation was organic - inorganic corn-pound fertilizers (F2 ), bio -organic fertilizer and inorganic compound fertilizer (F4 ) 〉 inorganic compound fertilizer ( F1 ) 〉 bio - organic fertilizer ( F3 ) 〉 the control. The application of gypsum with organic - inorganic compound fertilizer or bio - organic fertilizer and inorganic compound fertilizer could significant improve the growth of corn. But the application of gypsum with inorganic compound fertilizer could significantly decrease the dry matter accumulation of corn in coastal saline soil. There were significant effects of fertilizer with gypsum ap- plication on the nutrient uptake of corn in coastal saline soil. The N uptake in organic - inorganic compound fertilizers ( F2) was higher, and the K uptake in inorganic compound fertilizer ( F1 ) was higher in the nutrient up- take of corn in seeding stage. There was not significant effect of gypsum application on nutrient uptake of potting corn in coastal saline soil, but gypsum application could significantly decrease the P uptake. The appropriate fer- tilizer variety ic compound during corn cultivation was organic - inorganic fertilizer ( F2 ) or bio - organic fertilizer and inorgan- fertilizer (F4) with gypsum application in coastal saline soil.%通过盆栽试验,研究了肥料与石膏配合

  8. Fixação biológica de nitrogênio e teores foliares de nutrientes na soja em função de doses de molibdênio e gesso agrícola Biological nitrogen fixation and leaf nutrient concentration on soybean as a function of molybdenum and gypsum levels

    Evandro Gelain


    Full Text Available A competitividade econômica da soja brasileira no mercado mundial se deve, em grande parte, aos benefícios da fixação biológica do nitrogênio na cultura. O trabalho foi conduzido a campo, sob sistema plantio direto, em condição de sequeiro, no Município de Maracaju-MS, com o objetivo de avaliar a nodulação, o crescimento, nutrição mineral e produtividade de grãos da soja submetida a diferentes doses de gesso agrícola e molibdênio. Foi utilizado o delineamento experimental de blocos ao acaso, com cinco repetições e esquema de parcelas subdivididas, sendo as parcelas representadas por quatro doses de gesso agrícola (0, 1.000, 2.000 e 3.000 kg ha-1 e as subparcelas, por quatro doses de molibdênio (0, 20, 40 e 60 g ha-1. Não houve efeito da interação gesso x Mo sobre a produtividade da soja. O gesso agrícola não influencia no teor foliar de N e na produtividade. O Mo proporciona incrementos na produtividade e no teor de proteínas dos grãos.The economic competitiveness of Brazilian soybeans on the world market occurs, in large part, due to the benefits of biological nitrogen fixation in this crop. The field experiment was carried out in Maracaju, Mato Grosso do Sul State, Brazil, under no-tillage system, in rainfed condition. The aim was to evaluate nodulation, growth, mineral nutrition and grain yield of soybeans under different doses of gypsum and molybdenum. The experimental design used was a randomized block with five replicates and arranged in a split-plot squeme, with the plot represented by four doses of gypsum (0, 1.000, 2.000 and 3.000 kg ha-1 and the subplots by four doses of molybdenum (0, 20, 40 and 60 g ha-1. There were no interaction effects of Mo x gypsum for grain yield. Gypsum has no influence in the N leaf content and grain yield. Mo increases grain yield and protein levels in the grain.

  9. Early Stage Hydration Process of Cementitious Material Prepared with Red Mud, Slag, Gypsum and Small Smounts of Cement Clinker%赤泥-矿渣-石膏-少熟料胶凝材料的初期水化过程

    祝丽萍; 倪文; 高术杰; 王中杰; 张玉燕


    赤泥-矿渣-石膏-少熟料胶凝材料在胶结充填过程中表现出良好的保水性及早强、高强等性能,可以作为充填专用胶结剂.本文综合净浆试块的凝结时间、强度发展以及扫面电镜下的微观结构,分析了材料的初期水化过程,并采用XPS研究了不同元素之间旧组合分解和新组合的形成.结果表明水化3h时体系生成Ca(OH)2和凝胶类物质,这些水化产物使得浆体凝结硬化.4h后矿渣中的部分硅氧四面体参与反应,缩聚成了聚合度较高的硅酸盐矿物,净浆试块产生强度.水化6h后,S2 p3/2的结合能大幅增长,体系生成了较多的硫酸盐矿物,它们对强度的发展起到了较大作用.%The cementitious material prepared with red mud, ground granulated blast furnace slag ( GGBS) , flue gas desulfurization gypsum ( FGDG) and a small amount of cement clinker obtained good performances in water-retention, early strength and high strength when it used for cemented backfilling. This material can be used as special cement for backfilling. The early stage hydration of the material was analyzed through the setting time, strength development and microstructure. The decomposition of old system and the formation of the new mineral were also studied by X-ray photoelectron spectroscopy (XPS). Results show that Ca(0H)2 and gels formed at 3 h after hydration, resulting in the setting and hardening for the cement paste. The samples obtained strength at 4 h, which is attributed to the formation of silicates with higher polymerization degree, which condensed from oxygen-silicon tetrahedron. At 6 h, the binding energy of S2 p3/2 increased suddenly, and some sulfate minerals formed, which made a great contribution to the rise of strength.

  10. Modification of waterproof property for foamed polystyrene grain and foaming gypsum thermal insulation material%聚苯颗粒/发泡石膏保温材料的防水性能改性

    潘红; 高子栋


    采用掺加自制憎水性能优异的SFA防水剂和外喷甲基硅酸钠防水剂两种方式对聚苯颗粒/发泡石膏保温材料进行复合防水改性,研究了不同掺量SFA防水剂对保温材料吸水率、软化系数、密度、导热系数和绝干抗折抗压强度的影响,以及SFA防水剂最优掺量下外喷不同次数甲基硅酸钠防水剂对保温材料吸水率、软化系数的影响,并分析了其作用机理。结果表明:当SFA防水剂的掺量为16%并外喷三次甲基硅酸钠防水剂时,保温材料的各项性能明显改善,其中2h、24h吸水率分别降至40.30%、40.36%,软化系数升高至0.61。%The waterproof property of foamed polystyrene grain and foaming gypsum thermal insulation material is modified by SFA waterproof agent with good hydrophobic property and spraying methyl-sodium. The influences of SFA waterproof agent on the absorption rate, softening coefficient, density, coefficient of thermal conductivity and dry flexural, compressive strength of insulation material are investigated. Based on doping the optimum amount of SFA waterproof agent, the effects of different spraying times of methyl-sodium on the absorption rate and softening coefficient are studied, and their mechanism is also analyzed. The experimental results show that the properties of the thermal insulation material are improved obviously with doping of 16%of SFA waterproof agent and spraying methyl-sodium 3 times. The absorption rates for 2h and 24h reduce to 40.30%and 40.36%respectively and the softening coefficient rises to 0.61.

  11. 测井资料在膏盐地层钻井工程中的应用%Application of Log Information to Drilling Engineering of Salt and Gypsum Layers

    吴海燕; 陆黄生; 张元春


    膏盐层地层最大、最小水平主应力在盐岩含量高的地层中表现为较强的不均衡性,造成钻井施工过程中卡钻、井漏等事件时有发生.结合石膏、盐岩地层的沉积和地质特征,充分发挥钻井测井信息量大和连续测量、纵向分辨率高的优势,从地层岩石矿物分析、岩石力学参数计算、孔隙压力、破裂压力、地层应力评价等方法入手,分析测井资料在膏盐地层确定合理钻井液密度、性能、井身结构设计等方面的应用效果,拓宽测井在石油钻井工程中的应用领域.用于岩石力学参数实验的膏盐层钻井取心非常有限,建议适当增加膏盐层钻井取心.%Drill-pipe frozon and mud loss often appear in drilling operations because the maximum and minimum horizontal main stress is greatly non-isostatic. The drilled well's log data are used to evaluate rock constituents, formation stress and formation pressure, etc. , which is very important in designs about drilling fluid density, drill bit, wellbore structure and cementing of the same layers in near wells. And, formation lithology, clay and non-clay mineral composition, drilling fluid density, rock machanics parameters, pore pressure, fracturing pressure may be used to investigate complex downhole environments and determine preventive measures, which is also important in optimizing drilling fluids, mud program, mud property and mud maintenance, etc. At present, there are limited drill cores of the salt and gypsum layers used for rock mechanics parameters experiments, so it is suggested we should properly increase the drill cores of such layers.

  12. Utilização de uréia em misturas com sulfato de amônio ou com gesso na cultura de milho Use of urea in mix with ammonium sulfate or gypsum in the culture of corn

    Waldo Alejandro Ruben Lara Cabezas


    ês a quatro folhas e seis a sete folhas. A produtividade de grãos foi similar entre as fontes de U+SA e U+Gesso, sendo em média de 5.332 kg ha-1. Em Uberlândia, foram comparados os cinco tratamentos testados no experimento - safrinha de Votuporanga. As misturas de grânulos foram aplicadas em dose única de 90 kg ha-1 de N, no estádio de quatro a cinco folhas. Os maiores teores de N-mineral total foram detectados na camada de 0 a 10 cm de profundidade, em todos os tratamentos (abaixo de 3 mg dm-3, diminuindo em profundidade, enquanto o S-sulfato concentrou-se entre as camadas de 10 a 60 cm. Os tratamentos de U+Gesso e U+SA apresentaram, em média, produtividades de 11.364 e 10.300 kg ha-1 de grãos, respectivamente. O custo de aplicação de U+Gesso gr foi 27,7 % superior aos custos médios de aplicação de U+SAgr e U+SAfa, devido a seu menor teor de N, e 7,8 % superior em relação aos custos diretos totais por hectare. A mistura NK com aplicação posterior de U+Gesso pó apresentou custo de aplicação similar ao da U+Gesso gr, devido à dupla operação de aplicação do primeiro. Os resultados em ambas as regiões permitem concluir que o milho respondeu de forma similar à aplicação em cobertura das fontes mistas, U+SA e U+Gesso, independentemente da granulometria dos produtos, e que os custos de aplicação das formas U+Gesso foram superiores aos das misturas U+SA.Qualitative and quantitative aspects must be considered in the side-dressing fertilization in the cultivation of corn. This study aimed to evaluate in the counties of Votuporanga (SP and Uberlândia (MG, the effect on productivity of corn using different mixtures of granules in the side-dressing fertilization, containing nitrogen (N and sulphur (S. In Votuporanga (SP, in an Argisol (120 g kg-1 of clay were estimated losses through volatilization of NH3-N granules mix consisting of urea (U + ammonium sulfate (AS or U + Gypsum applied in the first split of nitrogen application. In Uberlândia (MG

  13. Thermochemical reduction of pelletized gypsum mixed with ...


    Apr 3, 2015 ... 4Department of Chemical and Metallurgical Engineering, Tshwane University of Technology, Pretoria 0001, South ... to CaS, an important intermediate for synthesis of a number of ... Thermal decomposition is the process used for the conver- .... Coal proximate analyses was performed by the South African.

  14. Quality control of gypsum “Plasterboard”

    Editorial, Equipo


    Full Text Available Not availableEl primer yeso plasterboard producido consistía en dos capas externas de cartón sujetando un núcleo de yeso que; a su vez, contenía dos o más capas adicionales de papel, separada cada una de ellas por una delgada capa de yeso. Los pioneros del plasterboard tenían la idea completamente errónea de que esta multilaminación de papel y yeso era necesaria para producir un panel ligero de peso, flexible y que podía clavarse fácilmente; sin embargo, se apreció que cualquier intento de penetración de un clavo a través de una placa de plasterboard sólido, la fracturaba en todas las direcciones. Los modernos fabricantes de plasterboard han superado todas estas objeciones, empleando un yeso de París cuidadosamente controlado para formar un núcleo de yeso completamente celular, que se encuentra encajado sólo en dos láminas de cartón especialmente preparado.

  15. 石膏和小夹板外固定治疗小儿肱骨髁上骨折临床疗效比较%Clinical comparison between gypsum and small splint external fixation on treating supracondylar fracture of humerus in children



    Objective:To explore clinical effects of gypsum and small splint external fixation on supracondylar fracture of humerus in children. Methods:The clinical effects in gypsum group and splint group were observed and compared, 42 cases for each. Results:The clinical efficacy in two groups was 85.71%and 83.33%respectively with no significant differences (P>0.05). Conclusion:Clinical effects of two kinds of external fixation are similar;both can be used to treat supracondylar fracture of humerus in children.%目的:探究石膏和小夹板外固定治疗小儿肱骨髁上骨折临床疗效。方法:石膏组和夹板组各42例,观察对比两组近期临床疗效。结果:石膏组和夹板组近期优良率分别为85.71%和83.33%,差异无统计学意义(P>0.05)。结论:两种外固定的临床疗效相似,均可作为治疗小儿肱骨踝上骨折外固定治疗措施。

  16. Effects of Fertilizer with Gypsum Application on Growing Development and Nutrient Uptake of Potting Rape in Coastal Saline Soil%肥料与石膏配施对滨海盐土油菜生长及养分吸收的影响

    李孝良; 陈效民; 徐克琴; 肖瑞; 王晓洋


    通过盆栽试验,研究了肥料与石膏配合施用对滨海盐土油菜生长及养分吸收的影响,探讨了滨海盐土适宜的肥料品种。结果表明,肥料与石膏配合施用对滨海油菜生长有显著影响,在油菜干物质累积、油菜产量上均以有机无机复混肥、生物有机肥配合无机复混肥配施石膏效果最好。供试肥料品种间,油菜生长中后期在干物质累积、产量上均表现出有机无机复混肥(F2)、生物有机肥配合无机复混肥(F4)〉无机复混肥(F1)〉生物有机肥(F3)〉对照,各肥料较对照分别增产195.6%、190.9%、117.0%和53.4%。在有机无机复混肥、生物有机肥配合无机复混肥的基础上增加石膏的施用量可明显改善油菜生长状况和产量,但在无机复混肥基础上增加石膏施用量会导致油菜干物质累积和产量的明显降低。肥料与石膏配合施用影响油菜对N、P、K养分的吸收,在油菜苗期养分吸收上,N、K以无机复混肥(F1)较高,P以有机无机复混肥(F2)较高,施用石膏可促进油菜对N、K的吸收,但会显著降低对P的吸收量。滨海盐土地区油菜栽培以有机无机复混肥(F2)、生物有机肥配合无机复混肥(F4)配合石膏(B2)施用较为适宜。%The effects of fertilizer with gypsum application on growing development and nutrients uptake of rape with the pot experiments in coastal saline soil were studied. The appropriate fertilizer varieties were discussed. The results were as follows: there were significant effects in fertilizer and gypsum application on rape growth in coastal saline soil. The dry matter accumulation and rapeseed yield in treatments of organic-inorganic fertilizer or bio-organic fertilizer and inorganic compound fertilizer with gypsum were the best. During rapeseed growth period and among the tested fertilizer varieties, the order of the dry matter accumulation

  17. Influence of fly ash, activator and waterproofing agent on the properties of thermal insulation gypsum block%粉煤灰、激发剂和防水剂对石膏自保温砌块性能的影响

    刘研; 李国忠


    Influence of fly ash, activator and waterproofing agent on the properties of thermal insulation gypsum block is researched. The research results show that when the content of fly ash is up to 25%, the mechanical properties of samples is best; when the activator reaches 1.5%, dry bending strength increases 36.5%, dry compressive strength increases 27.6%;when the organosilicon waterproofing agent content is 0.4%, the water absorption rates for 2 h and 24 h respectively are 3.5%and 4.2%, comparing the gypsum sample, the water absorption rate reduces respectively 88.3%and 87%.%研究结果表明,当粉煤灰掺量达到25%时,试样的力学性能最好;当激发剂掺量达到1.5%时,绝干抗折强度增加了36.5%,绝干抗压强度增加了27.6%;当有机硅防水剂掺量为0.4%时,2 h和24 h的吸水率分别为3.5%和4.2%,相比于空白试样,吸水率分别降低了88.3%和87%。

  18. 中低品位磷矿生产磷酸联产石膏晶须技术现状%Present Status of Technology for Co-Production of Phosphoric Acid and Gypsum Whiskers from Medium-and Low-Grade Phosphate Rock

    石学勇; 王金铭


    阐述了中低品位磷矿生产磷酸联产石膏晶须工艺技术的意义,并介绍了该工艺技术的基本原理和应用前景.采用盐酸和硫酸萃取磷矿并添加活性添加剂提高磷矿萃取速度和磷矿分解率,分离酸不溶物和部分杂质(铁、铝、镁),然后采用硫酸脱钙获得石膏晶须和磷酸,为中低品位磷矿综合利用提供了一条可行的途径.%A description is given of the technology for the co-production of phosphoric acid and gypsum whiskers from medium- and low-grade phosphate rock and its significance, also the fundamental principles of the technology and prospects for its use. Hydrochloric acid and sulfuric acid react with phosphate rock with the addition of an active additive to increase the extraction rate and decomposition rate of the rock, the acid-insolubles and some impurities ( iron, aluminum and magnesium) are separated out, and then sulfuric acid is used for decalcification to obtain phosphoric acid and gypsum whiskers, thereby providing a feasible route for comprehensive utilization of medium-and low-grade phosphate rock.

  19. Amelioration of Moderate Saline-alkali Soil by Desulfurized Gypsum Application and the Resulting Effect on the Growth and Rhizosphere Environment of Avena Sativa%脱硫废渣改良中度苏打碱土对燕麦生长与根际环境的影响

    许清涛; 李玉波; 闫守刚; 李晓东; 高标


    通过盆栽的方法,以脱硫废渣改良苏打碱土种植燕麦,测试不同脱硫废渣施用量对土壤pH、含盐碱量和燕麦的株高、生物量的影响。结果表明:与原始土壤相比,pH 值分别降低了0.40、1.10、1.12、1.17、1.12;EC 值分别增加了-0.19、0.40、0.77、0.84、0.87 mS/cm;当脱硫石膏的施用量为45 t/hm2时,生长期和收割期的燕麦株高与对照相比分别增加了28.23%和91.00%,燕麦全株干质量和根干质量分别增加了98.33%和30.40%。因此,脱硫废渣可以明显改善苏打盐碱土的理化性质,有利于燕麦的生长。%This study evaluated the ameliorating effect of applying desulfurized gypsum on moderate saline-alkali soil and the resultant impact on the growth of Avena sativas.Using the Avena sativas variety Baiyan No.2,a pot trial was conducted,which involved five treat-ments:a control (not treated with desulfurized gypsum)and treatments 1,2,3,and 4 in which desulfurized gypsum was applied at the rates of 15,30,45,and 60 t/hm2,respectively.Consequently,the pH value of the soda saline soil decreased by 1.1,1.12,1.17 and 1.12 in treatments 1,2,3,and 4,respectively,while the pH value in the control only declined by 0.40.In addition,treatments 1,2, 3,and 4 showed an increase in EC value by 0.40,0.77,0.84,and 0.87 mS/cm,respectively,in comparison with a decrease in EC by 0.19 mS/cm in the control.In relation to the control,application of desulfurized gypsum at the rate of 45 t/hm2 increased plant height by 28.23% and 91.00% in growing period and harvest time,respectively;and also elevated dry masses of plant and roots at harvest time by 98.33% and 30.40%,respectively.Therefore,application of desulfurization gypsum effectively improved the chemical proper-ties of the soda saline soil,resulting in a growth-promoting effect on Avena sativa.

  20. 脱硫石膏-粉煤灰地聚合物抗压强度和反应机理%Compressive Strength and Mechanism of Geopolymers from Flue Gas Desulferization Gypsum and Fly Ash

    郭晓潞; 施惠生


    The sodium water glass activated geopolymers were prepared from solid wastes of fly ash and flue gas desulfurization gypsum (FGDG). Compressive strength and mechanism of these geopolymers were also studied by using X ray diffraction (XRD) and scanning electron microscopy (SEM). When the FGDG baked at 800℃ for 1 h the FGDG had a more flabby structure and disfigurement, and became more active. The blend of 90% of fly ash and 10% of FGDG baked at 800℃ for 1 h was activated by sodium water glass, and the geopolymer was formed and the specimens were demoulded. The compressive strength of these geopolyme specimens cured at 23℃ for 28 days or at 75℃ for 8 h reached 37. 0 MPa. Activated by alkali activator and sulfate activator, geopolymerization products and hydration products of geopolymeric gel, zeolite, and ettringite etc. were formed. Preparation of geopolymes from fly ash and FGDG is beneficial for utilizing of multi industrial wastes, especially, the wastes containing silicate, aluminum, and sulfate.%经钠水玻璃激发固体废弃物脱硫石膏和粉煤灰,成功研制了脱硫石膏-粉煤灰地聚合物,研究了该地聚合物的抗压强度,并采用X射线衍射分析(XRD)和扫描电镜(SEM)等测试方法研究了其反应机理.研究表明:经800℃焙烧1h后的脱硫石膏结构松弛、缺陷多、活性大,以10%掺量取代粉煤灰,经钠水玻璃激发形成的地聚合物,在75℃养护8h或在23℃养护至28 d,抗压强度均可达37.0 MPa.此反应体系中,碱激发与硫酸盐激发作用共存,地聚合反应与水化反应同时进行,生成了地聚合物凝胶、类沸石以及钙矾石等反应产物.脱硫石膏-粉煤灰地聚合物的成功研制,为实现多种工业废弃物的共处置利用,尤其是含硅铝相的工业废弃物和含硫酸钙的工业废弃物的共处置打下了理论基础.

  1. Production of 34S-labeled gypsum (Ca34SO4.2H2O Produção de gesso (Ca34SO4.2H2O, marcado com 34S

    Alexssandra Luiza Rodrigues Molina Rossete


    Full Text Available Agricultural gypsum (CaSO4.2H2O stands out as an effective source of calcium and sulfur, and to control aluminum saturation in the soil. Labeled as 34S it can elucidate important aspects of the sulfur cycle. Ca34SO4.2H2O was obtained by chemical reaction between Ca(OH2 and H2(34SO4, performed under slow agitation. The acid was produced by ion exchange chromatography using the Dowex 50WX8 cation exchange resin and a Na2(34SO4 eluting solution. After precipitation, the precipitate was separated and dried in a ventilated oven at 60ºC. From 2.2 L H2SO4 0.2 mol L-1 and 33.6 g Ca(OH2, 73.7 ± 0.6 g Ca34SO4.2H2O were produced on average in the tests, representing a mean yield of 94.6 ± 0.8%, with 98% purity. The 34SO2 gas was obtained from Ca34SO4.2H2O in the presence of NaPO3 in a high vacuum line and was used for the isotopic determination of S in an ATLAS-MAT model CH-4 mass spectrometer.O gesso agrícola (CaSO4.2H2O destaca-se como fonte eficiente de cálcio e enxofre e na redução da saturação de alumínio no solo. O 34S como traçador isotópico pode elucidar aspectos importantes no ciclo do enxofre. Para tanto o Ca34SO4.2H2O foi obtido por reação química entre o Ca(OH2 e solução de H2(34SO4, realizada sob agitação lenta. O ácido foi produzido por cromatografia de troca iônica, utilizando resina catiônica Dowex 50WX8 e solução eluente de Na2(34SO4. Após a precipitação foi separado o precipitado e realizada a secagem em estufa ventilada à temperatura de 60ºC. Nos testes, a partir de 2,2 L de H2SO4 0,2 mol L-1 e 33,6 g de Ca(OH2, foram produzidos em média 73,7 ± 0,6 g de Ca34SO4.2H2O representando um rendimento médio de 94,6 ± 0,8%, com pureza de 98%. A partir do Ca34SO4.2H2O na presença de NaPO3, em linha de alto vácuo, obteve-se o gás 34SO2 utilizado para a determinação isotópica do S no espectrômetro de massas ATLAS-MAT modelo CH-4.

  2. Effects of sulfonated melamine formaldehyde onαhemihydrate gypsum in hydration process,structure and properties%磺化三聚氰胺对α半水石膏水化进程、结构和性能的影响

    赵辉; 任小明; 蒋涛; 周威; 涂照康; 安健鑫; 江莉莉


    Thermo gravimetric analyzer(TG)、scanning electron microscope(SEM)and hydration temperature test were used to research the effects of sulfonated melamine formaldehyde superplasticizer(SMF) on αhemihydrate gypsum in hydration process,microstructure of the hydration products,the water requirement at standard consistency and compressive strength. Results showed that it could decelerate the whole hydration process of α hemihydrate gypsum,the best dosage doped was 0.4%,the water requirement at standard consistency could be reduced by 22.22%at most and the compressive strength could be increased by 47.56%at most;SMF could give a more compact structure and increase the particle size of gypsum crystals ,it also could increase the internal stress and break the crystal network.%利用热重分析(TG)、扫描电子显微镜(SEM)和水化温度等测试手段分别研究了高磺化度三聚氰胺超塑化剂(SMF)对α半水石膏水化反应进程,硬化体微结构,标准稠度需水量和抗压强度等力学性能的影响.结果表明:SMF可以降低α半水石膏水化速率;SMF最佳掺量为0.4%,此时α半水石膏标准稠度需水量最高可以降低22.22%,硬化体抗压强度最高可以提高47.56%;SMF可以增加硬化体结构致密度,增大石膏晶体粒径,但也会增加体系内应力并破坏硬化体结晶网络.


    Yara Brito Chaim Jardim Rosa


    Full Text Available

    Amostras de um Latossolo Vermelho Distroférrico, coletadas sob três condições de uso, foram incubadas com calcário, em doses para a obtenção de 0%, 60% e 100% de saturação por bases, e com gesso agrícola, nas doses 0 kg ha-1, 500 kg ha-1, 1000 kg ha-1 e 2000 kg ha-1. Utilizou-se o delineamento experimental inteiramente casualizado, em esquema fatorial 3x3x4, com quatro repetições. Após a aplicação dos corretivos, as amostras de solo foram incubadas por um período de 45 dias. Em seguida, procederam-se as análises físicas e químicas especificadas. Observou-se que, independentemente do uso do solo, houve uma correlação inversa (r = -0,9801; p < 0,01 entre os valores de argila dispersa em água (ADA e o grau de floculação. Em solos submetidos a culturas anuais, sem o uso de calcário, obtiveram-se maiores valores de ADA que naqueles submetidos à pastagem ou sob vegetação nativa. A calagem em solos sob pastagem, com doses para elevação da saturação de bases a 60%, proporcionou aumentos nos valores de agregados maiores que 1,0 mm. O gesso induziu aumentos no grau de floculação, independentemente da dose ou do tipo de uso do solo.

    PALAVRAS-CHAVE: Manejo do solo; calagem; gessagem.

    Samples of a savannah dystroferric Oxisol were collected from three management systems, incubated with lime to 0%, 60% and 100% base saturation, and with agricultural gypsum to 0 kg ha-1, 500 kg ha-1, 1,000 kg ha-1 and 2,000 kg ha-1. A completely randomized 3x3x4 factorial experimental design was used, with four replications. After lime and gypsum application, soil samples were incubated for 45 days. Afterwards, physical and chemical analyses were

  4. Organic residue, limestone, gypsum, and phosphorus adsorption by lowland soils Resíduo orgânico, calcário e gesso e a adsorção de fósforo por solos de várzea

    Alex Teixeira Andrade


    Full Text Available Organic residue application is a low cost alternative to reduce the use of inorganic fertilizers and correctives. In order to study the effect of organic residues, limestone and gypsum application on phosphorus adsorption by lowland soils, four experiments were carried out. A Mesic Organosol (OY, a Melanic Gleysol (MG, a Haplic Gleysol (GX, and a Fluvic Neosol (RU were used in a completely randomized design and factorial scheme (3 x 2, with five replicates: three soil amendment practices (limestone, gypsum and no corrective and two levels of organic residue (with and without corral manure. Soil samples were incubated for 60 days, with and without organic residue incorporation. After this period, we applied the corrective and incubated the soil for 30 days, then P and basic fertilization (macro and micronutrients were applied and the soil was incubated for additional 60 days. Equilibrium phosphorus, maximum phosphate adsorption capacity, pH, exchangeable Al and phosphorus-buffering index were measured. Organic residue and limestone application increased soil pH and reduced exchangeable Al, decreasing P adsorption. Gypsum application did not increase the pH but reduced exchangeable Al and P adsorption.A aplicação de resíduo orgânico é uma alternativa de baixo custo para reduzir a aplicação de fertilizantes inorgânicos e corretivos. Com objetivo de estudar a relação da aplicação de resíduo orgânico, calcário e gesso com adsorção de fósforo em solos de várzea conduziram-se simultaneamente quatro experimentos com os solos Organossolo Mésico (OY, Gleissolo Melânico (GM, Gleissolo Háplico (GX e Neossolo Flúvico (RU. O delineamento experimental utilizado foi o inteiramente casualizado, em esquema fatorial 3x2, com cinco repetições, sendo três práticas de correção do solo (calcário, gesso e sem corretivo e dois níveis de resíduo orgânico com e sem esterco de curral curtido. Amostras dos solos foram incubadas por 60 dias

  5. Aplicação de gesso agrícola e especiação iônica da solução de um Latossolo sob sistema plantio direto Gypsum application and ionic speciation of the solution from an Oxisol under no-till system

    Fernando César Bachiega Zambrosi


    Full Text Available O baixo teor de Ca e a toxicidade por Al são importantes limitações à produtividade das culturas em solos ácidos brasileiros. É possível aumentar o teor de Ca e reduzir a toxicidade por Al por meio da aplicação de gesso agrícola. No entanto, é importante melhor compreensão dos efeitos do gesso na especiação iônica da solução do solo. Avaliou-se a especiação iônica da solução do solo (extrato aquoso 1:1 de amostras de um Latossolo Vermelho distrófico textura argilosa, sob sistema plantio direto, cinco anos após a aplicação superficial de 3, 6 e 9t ha-1 de gesso agrícola. A especiação foi realizada com auxílio do programa computacional Visual Minteq em amostras coletadas nas profundidades de 0-0,05; 0,05-0,1; 0,1-0,2 e 0,2-0,4m. Para o Al, as principais espécies químicas foram os complexos com carbono orgânico dissolvido (Al-COD e com F (Al-F, enquanto o par iônico AlSO4+ ocorreu em pequena proporção. O COD foi o principal ligante para Mg e Ca, mas em muito maior magnitude para este último, refletindo importante participação dos ânions orgânicos na dinâmica desses nutrientes. Em relação ao sulfato, apesar da formação dos pares iônicos com Ca, Mg e Al (CaSO4(0, MgSO4(0 e AlSO4+, houve a predominância da forma livre S-SO4-2, enquanto o fosfato apresentou forte interação com o Al em solução, formando a espécie química Al-HxPO4x.Low Ca content and Al toxicity are important limitations for yield crops in Brazilian acids soils. Gypsum application may increase Ca contents and decrease Al toxicity. However, a better knowledge of the effects of gypsum on the ionic speciation of soil solution is very important. The ionic speciation of the soil solution (water extract 1:1 was evaluated in samples from a dystrophic clayey Rhodic Hapludox under no-till system, 5 years after surface application of gypsum (3; 6 and 9t ha-1. The ionic speciation was performed by using the Visual Minteq program in samples

  6. Modificações químicas em solos ácidos ocasionadas pelo método de aplicação de corretivos da acidez e de gesso agrícola Chemical modifications in acid soils caused by addition of gypsum or limestone

    Paulo Roberto Ernani


    Full Text Available Os benefícios do calcário aplicado sobre a superfície do solo no rendimento vegetal podem estar associados à melhoria na composição química das águas de percolação. Esse trabalho objetivou avaliar alterações na fase sólida e na solução percolada em dois solos ácidos (Latossolo Bruno Álico e Cambissolo Húmico Álico, ocasionadas pelo método de aplicação (na superfície ou incorporado de corretivos da acidez (CaCO3 e MgCO3 e de gesso agrícola. O CaCO3 foi utilizado na dose equivalente a 0,25 daquela necessária para elevar o pH a 6,0, e os demais em doses molares equivalentes. O CaCO3 foi ainda incorporado nas doses de 0; 0,5; 1,0 e 1,5 vez a necessidade de calcário para pH 6,0. Em colunas de lixiviação, com 1,5 kg de solo, percolou-se água destilada durante 12 semanas num volume de 200 mL semana-1. Os corretivos da acidez, quando incorporados aos solos, aumentaram o pH das duas fases, diminuíram o Al trocável, porém não afetaram o Al percolado; quando foram aplicados na superfície, não afetaram nenhum parâmetro da solução percolada, e alteraram a composição química somente da camada de 0 a 2,0 cm de profundidade. O gesso agrícola diminuiu o pH do solo e da solução percolada, não afetou o Al trocável, mas percolou muito mais Ca, Mg e Al que os corretivos da acidez, principalmente quando foi incorporado ao solo. A mobilidade dos cátions integrantes dos corretivos foi muito pequena, e a aplicação de calcário na superficie dos solos não afetou a composição química da solução coletada 30 cm abaixo.The increase on crop yield caused by lime addition on the soil surface may be associated to improvements in the chemical composition of the percolating water. This study was carried out to evaluate chemical changes in the solid phase and in the percolating water in two acid soils (Oxisol and Inceptisol caused by the application method (incorporated or on soil surface of gypsum, CaCO3, or MgCO3. Calcium

  7. Efeitos de métodos de estabelecimento de braquiária e estilosantes e de doses de calcário, fósforo e gesso sobre alguns componentes nutricionais da forragem Effect of establishment methods of brachiaria and stylosanthes, limestone, gypsum and phosphorus on some forage nutritional components

    Eduardo Eustáquio Mesquita


    Full Text Available Um experimento foi conduzido com o objetivo de avaliar, em dois anos, os efeitos de métodos de estabelecimento (sulcamento: 1,5 e 1,0 m entre linhas em etapa única; 1,5 e 1,0 m em duas e três etapas, respectivamente; aração, gradeação e sulcos espaçados de 1,0 m entre linhas, doses de calcário (25, 50, 75 e 100% da necessidade de calagem-NC, obtida pelo método do Al, Ca e Mg trocáveis, gesso agrícola (0, 230, 940, 1.880 e 2.820 kg/ha, referentes à substituição de 0, 3,0, 12,5, 25,0 e 37,5% do CaO do calcário pelo CaO do gesso, na dose de 100% da NC e P2O5 (50, 100, 150, 200 e 250 kg/ha nas concentrações de minerais (P, K, Ca, Mg e S, proteína bruta (PB, fibra em detergente neutro (FDN, fibra em detergente ácido (FDA e lignina na matéria seca e na DIVMS de Brachiaria decumbens consorciada com Stylosanthes guianensis cv. Mineirão. Os métodos de estabelecimento em duas e três etapas propiciaram maiores concentrações de K na braquiária e Ca no estilosantes. As maiores concentrações de PB na braquiária foram alcançadas com o estabelecimento com aração e gradeação do solo. A substituição do calcário pelo gesso elevou as concentrações de S, Ca e PB na matéria seca da braquiária e do estilosantes e reduziu as concentrações de FDN na gramínea. As doses de P elevaram as concentrações de P, PB e a DIVMS e reduziram as concentrações de FDN na braquiária, melhorando seu valor nutritivo.A field trial was carried out to evaluate the establishment methods (Furrow only: row 1,5 and 1,0 m apart at one time; 1.5 and 1.0 at two and three times, respectively; Plowing and horrowing: row 1,0 apart, limestone (25, 50, 75 e 100% of necessity of limestone, obtained by Al, Ca e Mg exchangeable, gypsum (0, 230, 940, 1.880 e 2.820 kg/ha and P2O5 (50, 100, 150, 200 e 250 kg/ha on minerals concentration (P, K, Ca, Mg e S; crude protein (CP, neutral detergent fiber (NDF, acid detergent acid (ADF and in vitro dry matter

  8. Volatilização de amônia, lixiviação de nitrogênio e produtividade de milho em resposta à aplicação de misturas de uréia com sulfato de amônio ou com gesso agrícola Ammonia volatilization, leaching of nitrogen and corn yield in response to the application of mix of urea and ammonium sulphate or gypsum

    Waldo Alejandro Ruben Lara Cabezas


    , in the rate of 90 kg ha-1 of N, as exclusive U or AS, or mixtures of U+AS granulated (U+ASgr and U+AS with different size particles (U+ASfa and U+Gypsum granulated (U+Gypsum gr and U+Gypsum powder (U+Gypsum powder. The more significant gas losses of NH3-N were in decrecent order: U exclusive 76.8 % followed by U+ASgr 37,9 %; U+Gypsum gr 27.7 % and ASfa exclusive (7.8 %. The concentration of ammonium-N and nitrate-N after 37 days of the fertilizer application was similar to the control (without N, demonstrating that the N supplied by the fertilizers were assimilated by the crop, nitrified, leached and, or, adsorbed more deeply. The sulphate-S, at the superficial layer presented the lower concentration in all treatments, reducing its concentration in the layer of 0 to 10 cm, and the 37 to 51 days of the fertilizer applied. After 51 days of the mixtures application, the concentration of total mineral-N was more expressive in the layers of 20 and 40 cm deep, demonstrating the leaching of N from the superficial layers. In the treatments with exclusive application of U and AS this tendency was weaker. In general it had greater ratio of the nitrate-N that of ammonium-N in the total mineral-N in the analyzed layers. In relation to sulphate-S, was expressive increasing the concentration in deeper layers. In stage of flowering, the analysis of nutrients in the leaf opposite the spike showed no significant difference in the ratio N:S leaf, and, this relationship in the shoots of the plant. The highest yields were reached by the treatments of U+ASfa and U+Gypsum gr: 10.285 and 10.241 kg ha-1 of grains, respectively. The treatments with higher yields were the ones with U+ASfa or AS+Gypsum gr with the N:S ratios between 2,75 to 4,00. These results allow to conclude that the application of sulphur as side-dressing is necessary and it can be done by mixing U with AS or U and Gypsum gr, although this later one have presented significant higher NH3 losses.


    Wilson Mozena Leandro


    Full Text Available

    Aiming to verify the action of different soil correctives on the chemical characteristics of a dark red latosoil median texture, a two-years field experiment was carried out. A completely randomized design with 7 treatments (6 different soil correctives and a control with no liming and four repetitions were used. As soil correctives limestone (calcitic, dolomitic, calcinated dolomitic, and magnesian, gypsum and calcium hydroxide were employed. On the first year the experimental area was cropped with rice (Oryza sativa L. c.v. IAC-25 and on the second one with soybean (Glycine max L. Merrill c.v. IAC-8. Dolomitic limestone caused the greatest chemical alterations on soil characteristics, with increase on pH, K+, Ca+2 and Mg+2 and decrease on H+ + Al+3 values, during the first year. Losses of exchangeable Mg+ by leaching have been found during the second year, due to the use of gypsum and calcitic limestone. All liming materials, but gypsum, increased rice yields when compared with the control. The calcinated dolomitic limestone gave the highest soybean yields.

    KEY-WORDS: Soil; soil acidity; liming materials; pH.

  1. Obtention of agricultural gypsum traced on {sup 34} S (Ca{sup 34} SO{sub 4}.2H{sub 2}O), by chemical reaction between H{sub 2}{sup 34} SO{sub 4} and Ca(OH){sub 2}; Obtencao do gesso agricola marcado no {sup 34} S (Ca{sup 34} SO{sub 4}.2H{sub 2}O), por reacao quimica entre o H{sub 2}{sup 34} SO{sub 4} e Ca(OH){sub 2}

    Rossete, Alessandra L.R.M.; Bendassolli, Jose A.; Ignoto, Raquel de Fatima; Batagello, Hugo Henrique [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil). Lab. de Isotopos Estaveis


    The gypsum (CaSO{sub 4}.2H{sub 2}O) has double function in the soil: as source of calcium and sulfur and reducing agent of aluminum saturation. The sulfur for the plants has acting in the vital functions and it is proven fact increase of the S deficiency in Brazilian soils. The isotope tracer {sup 34} S can elucidate important aspects in the sulfur cycle. The Ca{sup 34} SO{sub 4}.2H{sub 2}O was obtained by chemical reaction between Ca(OH){sub 2} and H{sub 2}{sup 34} SO{sub 4} solution. The acid was obtained by chromatography ionic change, using cationic resin Dowex 50WX8 and Na{sub 2}{sup 34} SO{sub 4} solution. The reaction was realized under slow agitation. After the reaction, the precipitate was separated and dried in ventilated stove at 60 deg C temperature. The Mass of the Ca{sup 34} SO{sub 4}.2H{sub 2}O produced was determined by method gravimetric. This way, a system contends resin 426 cm{sup 3}, considering volume of 2.2 liters can be obtained a solution contends 44.2 g of H{sub 2}{sup 34} SO{sub 4}, theoretically could be produced 78.0 g of Ca{sup 34} SO{sub 4}.2H{sub 2}O approximately. With results of the tests were verified that there was not total precipitation of the Ca{sup 34}SO{sub 4}.2H{sub 2}O. Were produced 73.7{+-} 0.6 g of Ca{sup 34} SO{sub 4}.2H{sub 2}O representing average income 94.6{+-}0.8 %. The purity of the produced CaSO{sub 4}.2H{sub 2}O was 98%. (author)

  2. Thermal Behaviour of a Gypsum Fibre Board Associated with Rigid Polyurethane Foam under Standard Fire Conditions

    Dreau, Jerome Le; Jensen, Rasmus Lund; Kolding, Klaus


    , the thermal properties of the different materials at high temperature have been established. Then, a heat transfer model using temperature-dependent thermal properties and apparent specific heat capacity has been developed. Finally, the model has been compared to full-scale test results performed according......Due to its low thermal conductivity (λ ≈ 20 mW/m.K), rigid polyurethane (PUR) foam has the potential to improve the thermal performance of buildings without increasing the thickness of construction elements. Nevertheless, PUR foam has the drawback of having a low resistance to fire: non...

  3. Gypsum burning in one or several phases by suspension in a hot gas

    Steinkuhl, J.


    Full Text Available Not availableEn la industria europea del yeso la demanda de materiales de primera calidad es actualmente, con mucho, mayor que la que pueden ofrecer las capacidades de producción existentes. Debido a esto se sugiere la construcción de nuevas instalaciones capaces de acomodarse y producir de acuerdo con las circunstancias del mercado. La fabricación de los diferentes productos acabados de yeso se ha efectuado hasta la fecha en máquinas de construcción anticuada, o por procedimientos técnicamente nuevos pero complicados en su manejo y con elevados costes.

  4. Properties of expansive cements, made with Portland cement, gypsum and high alumina cement

    Monfore, G. E.


    Full Text Available Not availableLos cementos expansivos se han desarrollado durante las tres décadas pasadas, principalmente por las investigaciones llevadas a cabo en Francia, URSS y Estados Unidos. Los cementos expansivos que fueron utilizados en los estudios de los cuales se da cuenta en el presente trabajo se obtuvieron mediante la mezcla de cemento Portland, cemento aluminoso y yeso. En las investigaciones se utilizaron morteros con los cuales se pudo determinar los efectos de la composición, tiempo y temperatura de curado sobre las resistencias, dilatación libre, retracción y desarrollo de resistencias en probetas pretensadas. Se hace una revisión sobre los estudios hechos con cementos expansivos y desarrollados en la Universidad de California. Las propiedades de taIes hormigones son, en términos generales, comparables a aquellos obtenidos con mezclas de cementos portland, cemento aluminoso y yeso. Es necesaria más información sobre pérdidas de tensión en los aceros y durabilidad de los hormigones autopretensados.

  5. Moisture parameters and fungal communities associated with gypsum drywall in buildings

    Dedesko, Sandra; Siegel, Jeffrey A.


    Uncontrolled excess moisture in buildings is a common problem that can lead to changes in fungal communities. In buildings, moisture parameters can be classified by location and include assessments of moisture in the air, at a surface, or within a material. These parameters are not equivalent in dynamic indoor environments, which makes moisture-induced fungal growth in buildings a complex occurrence. In order to determine the circumstances that lead to such growth, it is essential to have a t...

  6. Effect of Cristobalite and Quartz on the Properties of Gypsum Bonded Investment


    Generally the gold investment material consists of cristobalite, quartz and plaster. The physical property of gold investment materials depends on its thermal expansion coefficients, compressive strength, and particles size distribution. Since the thermal expansion coefficient of cristobalite and quartz are 2.6×10-6/℃ and 2.32×10-6/℃ respectively, the composition ratio of each components influence the thermal and physical properties of gold investment materials. For the clinical applications, it is necessary to improve the properties of gold investment materials such as homogeneous size distribution and thermal expansion coefficients. In the present study, effect of inorganic fillers such as cristobalite and quartz on gold alloy investment was investigated to improve the properties of it. The compressive strength and thermal expansion coefficients of the specimens were evaluated. The results showed that cristobalite and quartz were homogeneously distributed by milling.The optimum compressive strength was obtained at the ratio of 42:22 cristobalite and quartz, respectively.

  7. Management of Phytophthora cinnamomi root rot disease of blueberry with gypsum and compost

    Root rot disease of blueberry caused by Phytophthora cinnamomi is becoming more prevalent as a consequence of widespread adoption of drip irrigation. This creates higher moisture content in the root zone more conducive for the pathogen. Options for disease control under organic management are limi...


    BING MA,


    Full Text Available The objective of this study was the preparation and characterization of high belite sulfoaluminate cement (HBSC from industrial residues. HBSC promises eco-friendly building materials with great mechanical performance at earlier ages than Ordinary Portland Cement (OPC. Preliminary results show the formation of main phase dicalcium silicate (C2S and ye’elimite (C4A3$ at 1250°C, as determined by X-ray diffraction (XRD, are promising. The formation of minerals in the clinker was analyzed by differential scanning calorimetry-thermogravimetry (DSC–TG. Likewise, Scanning electron microscope (SEM and XRD were used to carry out the analysis of the micro-structural and hydration products. The main HBSC hydration products, Ettringite and amorphous Al(OH3, were formed in the early stages; however, during the later stages, monosulfate and Strätlingite were formed. Isothermal conduction calorimetry measurements indicate that hydration properties of the cements are comparable to OPC; the total hydration heat after 3 days was 438 J/g. The optimum compressive strength values of the mortars after 1-, 3-, 7-, and 28-days were 24.9 MPa, 33.2 MPa, 35.6 MPa and 52.8 MPa which can meet the requirement of special structures.

  9. Gypsum plasterboard walls: inspection, pathological characterization and statistical survey using an expert system

    Gaião, C.


    Full Text Available This paper presents an expert system to support the inspection and diagnosis of partition walls or wall coverings mounted using the Drywall (DW construction method. This system includes a classification of anomalies in DW and their probable causes. This inspection system was used in a field work that included the observation of 121 DWs. This paper includes a statistical analysis of the anomalies observed during these inspections and their probable causes. The correlation between anomalies and causes in the sample is also thoroughly analyzed. Anomalies are also evaluated for area affected, size, repair urgency and aesthetic value of the affected area. The conclusions of the statistical analysis allowed the creation of an inventory of preventive measures to be implemented in the design, execution and use phases in order to lessen the magnitude or eradicate the occurrence of anomalies in DW. These measures could directly help improve the quality of construction.

    Este trabajo presenta un sistema experto de apoyo a la inspección y diagnóstico de tabiques o revestimientos de yeso laminado. Dicho sistema, que permite la clasificación de las anomalías del yeso laminado y sus causas probables, se empleó en un trabajo de campo en el que se estudiaron 121 elementos construidos con este material. El trabajo incluye el análisis estadístico de las anomalías detectadas durante las inspecciones y sus motivos probables. También se analizó en detalle la correlación entre las anomalías y sus causas, evaluándose aquellas en función de la superficie afectada, la urgencia de las reparaciones y el valor estético de la zona implicada. Las conclusiones del análisis estadístico permitieron la elaboración de un inventario de medidas preventivas que deberían implantarse en las fases de proyecto, ejecución y utilización de estos elementos a fin de erradicar la aparición de anomalías en el yeso laminado o reducir su frecuencia. Dichas medidas contribuirían directamente a la mejora de la calidad de la construcción.

  10. Chemical Alterations of Pb using Flue Gas Desulfurization Gypsum (FGDG) in two contaminated soils

    U.S. Environmental Protection Agency — The data include chemical composition of Pb contaminated soils by adding FGDG as an amendment. The data shows the changes in Pb speciation to sulfur based minerals....

  11. An Archeological Survey in the Gypsum Breaks on the Elm Fork of the Red River,


    Hughes (1973). One of the known sites was reported by James Shaeffer in 1960. The Hughes survey was based on an earlier plan to dam Fish Creek, and he...limits. Artifacts recovered include Trinity, Ensor , Darl, Ellis, Gary, Meserve, Frio, and Abasolo projectile points, Clear Fork gouges, burins and...Marcos, Ensor , Palmillas and Trinity. From the material of these four sites an estimated range of dates was proposed at 2000 B.C. to 1000 A.D. Eight

  12. Two distinctive new species of Commicarpus (Nyctaginaceae) from gypsum outcrops in eastern Ethiopia

    Friis, Ib; Gilbert, Michael G.; Weber, Odile;


    species: Commicarpus macrothamnus Friis & O. Weber sp. nov. is unique among all hitherto described species of Commicarpus, being a robust free-standing shrub, almost a small tree up to 3½ m high, with woody stems up to c. 12 cm in diam. Commicarpus leleensis Friis & Sebsebe sp. nov. is also unusual...... in Commicarpus, being a small self-supporting shrub to 0.8 (– 1) m high. Both new species occur in small populations with restricted distribution; models based on the available information show that the potential distribution is also restricted. C. macrothamnus is here evaluated as Vulnerable (VU), while C...

  13. Contribution to the determination of gypsum and hemihydrates content in Portland cements

    Moreno Arús, Fernando


    Full Text Available Not availableLa mayoría de los técnicos de cemento, aceptan, que las anormalidades del fraguado, conocidas como "falso fraguado" en el cemento portland, se deben primordialmente a la presencia de yeso parcialmente deshidratado (S04Ca1/2H20. Si el clínker que se muele está enriquecido en cal libre, o la temperatura del molino es elevada (superior a los 110 °C o hay escasa ventilación de éste, se llega a originar una parcial deshidratación del yeso, que se mantiene durante el proceso de ensilado y que origina las anormalidades del fraguado al que anteriormente nos hemos referido. Por esta razón creemos muy importante poder conocer el grado de deshidratación en que se encuentra el yeso en un cemento.

  14. Habitat Fragmentation Differentially Affects Genetic Variation, Phenotypic Plasticity and Survival in Populations of a Gypsum Endemic.

    Matesanz, Silvia; Rubio Teso, María Luisa; García-Fernández, Alfredo; Escudero, Adrián


    Habitat fragmentation, i.e., fragment size and isolation, can differentially alter patterns of neutral and quantitative genetic variation, fitness and phenotypic plasticity of plant populations, but their effects have rarely been tested simultaneously. We assessed the combined effects of size and connectivity on these aspects of genetic and phenotypic variation in populations of Centaurea hyssopifolia, a narrow endemic gypsophile that previously showed performance differences associated with fragmentation. We grew 111 maternal families sampled from 10 populations that differed in their fragment size and connectivity in a common garden, and characterized quantitative genetic variation, phenotypic plasticity to drought for key functional traits, and plant survival, as a measure of population fitness. We also assessed neutral genetic variation within and among populations using eight microsatellite markers. Although C. hyssopifolia is a narrow endemic gypsophile, we found substantial neutral genetic variation and quantitative variation for key functional traits. The partition of genetic variance indicated that a higher proportion of variation was found within populations, which is also consistent with low population differentiation in molecular markers, functional traits and their plasticity. This, combined with the generally small effect of habitat fragmentation suggests that gene flow among populations is not restricted, despite large differences in fragment size and isolation. Importantly, population's similarities in genetic variation and plasticity did not reflect the lower survival observed in isolated populations. Overall, our results indicate that, although the species consists of genetically variable populations able to express functional plasticity, such aspects of adaptive potential may not always reflect populations' survival. Given the differential effects of habitat connectivity on functional traits, genetic variation and fitness, our study highlights the need to shift the focus of fragmentation studies to the mechanisms that regulate connectivity effects, and call for caution on the use of genetic variation and plasticity to forecast population performance.

  15. Habitat Fragmentation Differentially Affects Genetic Variation, Phenotypic Plasticity and Survival in Populations of a Gypsum Endemic

    Silvia Matesanz


    Full Text Available Habitat fragmentation, i.e., fragment size and isolation, can differentially alter patterns of neutral and quantitative genetic variation, fitness and phenotypic plasticity of plant populations, but their effects have rarely been tested simultaneously. We assessed the combined effects of size and connectivity on these aspects of genetic and phenotypic variation in populations of Centaurea hyssopifolia, a narrow endemic gypsophile that previously showed performance differences associated with fragmentation. We grew 111 maternal families sampled from 10 populations that differed in their fragment size and connectivity in a common garden, and characterized quantitative genetic variation, phenotypic plasticity to drought for key functional traits, and plant survival, as a measure of population fitness. We also assessed neutral genetic variation within and among populations using eight microsatellite markers. Although C. hyssopifolia is a narrow endemic gypsophile, we found substantial neutral genetic variation and quantitative variation for key functional traits. The partition of genetic variance indicated that a higher proportion of variation was found within populations, which is also consistent with low population differentiation in molecular markers, functional traits and their plasticity. This, combined with the generally small effect of habitat fragmentation suggests that gene flow among populations is not restricted, despite large differences in fragment size and isolation. Importantly, population’s similarities in genetic variation and plasticity did not reflect the lower survival observed in isolated populations. Overall, our results indicate that, although the species consists of genetically variable populations able to express functional plasticity, such aspects of adaptive potential may not always reflect populations’ survival. Given the differential effects of habitat connectivity on functional traits, genetic variation and fitness, our study highlights the need to shift the focus of fragmentation studies to the mechanisms that regulate connectivity effects, and call for caution on the use of genetic variation and plasticity to forecast population performance.

  16. Evaluation of NPK 8-30-20 with gypsum addition compared to fertilization employed in the region for the production of potato (Solanumtuberosum L. Evaluación de NPK 8-30-20 con yeso en comparación a la fertilización convencional para la producción de la papa (Solanum tuberosum L. Avaliação da fórmula NPK 8-30-20 com adição de gesso agrícola em comparação à adubação convencional para produção de batata (Solanum tuberosum L.

    Douglas Jobim Vieira


    Full Text Available

    Different forms of fertilizer management are employed by potato farmers, and from time to time, it appears a receipt to fertilize the crop. However, one should pay special attention to nutrition and fertilization of the potato as the relative demand of fertilizer per unit area in culture is high. The objective was to evaluate the use of NPK 8-30-20 with the addition of gypsum compared to NPK 4-14-8 (regional standard treatment in the production of potato. The study was conducted at the Research Unit in Potato Production and Microclimate on Agriculture, Campus CEDETEG at UNICENTRO in Guarapuava - PR. The treatments were: T1 - 3.5 t ha-1 NPK 4-14-8, T2 - 3.5 t ha-1 NPK 4-14-8 over the application of 3 t ha-1 gypsum; T3 - 1.75 t ha-1 NPK 8-30-20, T4 - 1.75 t ha-1 NPK 8-30-20 plus the application of 3 t ha-1 gypsum, T5 - 1.75 t ha-1 NPK 8-30-20 plus the application of plaster to make up the difference between fertilizer. The cultivation of potato was held on December 23, 2008 and the cultivar used was Agatha. The seed used was Generation 01 and tubers of class II. The density used was 50.000 tubers per hectare. The experimental design was completely randomized design with five treatments and four replications. It was evaluated the productivity and classification of tubers of the size and incidence and severity of common scab (Streptomyces spp. and silver scurf (Helminthosporium solani Dur. And Mont. in the tubers. Statistical analysis was performed by ANOVA test and mean comparison by Tukey test (5%. Classification of the tubers was performed according to the diameter classes of the Ordinance No. 69 MAP of February 21, 2005. The use of manure at 5 t ha-1 NPK 4-14-8 over the application of 3 t ha-1 gypsum and 1.75 t ha-1 of 8-30-20 NPK plus the application of 3 t ha-1 gypsum causes the

  17. Visualization of the structural changes in plywood and gypsum board during the growth of Chaetomium globosum and Stachybotrys chartarum

    Lewinska, Anna Malgorzata; Hoof, Jakob Blæsbjerg; Peuhkuri, Ruut H.


    Fungal growth in indoor environments is associated with many negative health effects. Many studies focus on brown- and white-rot fungi and their effect on wood, but there is none that reveals the influence of soft-rot fungi, such as Stachybotrys spp. and Chaetomium spp., on the structure of build......Fungal growth in indoor environments is associated with many negative health effects. Many studies focus on brown- and white-rot fungi and their effect on wood, but there is none that reveals the influence of soft-rot fungi, such as Stachybotrys spp. and Chaetomium spp., on the structure...

  18. Quantifying mold biomass on gypsum board: Comparison of ergosterol and beta-N-acetylhexosaminidase as mold biomass parameters

    Reeslev, M.; Miller, M.; Nielsen, Kristian Fog


    Two mold species, Stachybotrys chartarum and Aspergillus versicolor, were inoculated onto agar overlaid with cellophane, allowing determination of a direct measurement of biomass density by weighing. Biomass density, ergosterol content, and beta-N-acetylhexosaminidase ( activity were...

  19. On Nonlinear Inverse Problems of Heat Transfer with Radiation Boundary Conditions: Application to Dehydration of Gypsum Plasterboards Exposed to Fire

    A. Belmiloudi


    Full Text Available The paper investigates boundary optimal controls and parameter estimates to the well-posedness nonlinear model of dehydration of thermic problems. We summarize the general formulations for the boundary control for initial-boundary value problem for nonlinear partial differential equations modeling the heat transfer and derive necessary optimality conditions, including the adjoint equation, for the optimal set of parameters minimizing objective functions J. Numerical simulations illustrate several numerical optimization methods, examples, and realistic cases, in which several interesting phenomena are observed. A large amount of computational effort is required to solve the coupled state equation and the adjoint equation (which is backwards in time, and the algebraic gradient equation (which implements the coupling between the adjoint and control variables. The state and adjoint equations are solved using the finite element method.

  20. Vertical distribution of bacteria and intensity of microbiological processes in two stratified gypsum Karst Lakes in Lithuania

    Krevs A.


    Full Text Available Physical-chemical parameters and the vertical distribution of bacteria and organic matter production-destruction processes were studied during midsummer stratification in two karst lakes (Kirkilai and Ramunelis located in northern Lithuania. The lakes were characterized by high sulfate concentrations (369–1248 mg·L-1. The O2/H2S intersection zone formed at 2–3 m depth. In Lake Kirkilai, the highest bacterial densities (up to 8.7 × 106 cell·mL-1 occurred at the O2/H2S intersection zone, whereas in Lake Ramunelis the highest densities were observed in the anoxic hypolimnion (up to 11 × 106 cell·mL-1. Pigment analysis revealed that green sulfur bacteria dominated in the microaerobic–anaerobic water layers in both lakes. The most intensive development of sulfate-reducing bacteria was observed in the anaerobic layer. Photosynthetic production of organic matter was highest in the upper layer. Rates of sulfate reduction reached 0.23 mg S2−·dm3·d-1 in the microaerobic-anaerobic water layer and 1.97 mg S2−·dm3·d-1 in sediments. Karst lakes are very sensitive to organic pollution, because under such impact in the presence of high sulfate amounts, sulfate reduction may become very intensive and, consequently, the increase in hydrogen sulfide and development of sulfur cycle bacteria may reduce the variety of other hydrobionts.


    Likhacheva Svetlana Yur'evna


    The findings of the prototype testing include identification of the two areas of deformations: areas of elastic deformations and areas of intensive development of deformations. The first area of partial elastic deformations is characterized by the linear stress function, while the second area demonstrates that this relationship is nonlinear. Permanent deformations appear as of the startup of the loading process and disproportionate stress is demonstrated throughout the deformation process. However, in the first area (partial elastic deformations residual deformations are so small that this area is considered as the area of "the area of incomplete elasticity".

  2. Conversion of calcium sulphide to calcium carbonate during the process of recovery of elemental sulphur from gypsum waste

    De Beer, Morris


    Full Text Available of hydrogen sulphide (H(sub2)S) and CaCO(sub3). H(sub2)S can subsequently be converted to elemental sulphur via the commercially available chemical catalytic Claus process. This study investigated the carbonation of CaS by examining both the solution chemistry...

  3. Synthesis of high-purity precipitated calcium carbonate during the process of recovery of elemental sulphur from gypsum waste

    De Beer, Morris


    Full Text Available (PCC). The process used an acid gas (H 2S) to improve the aqueous dissolution of CaS, which is otherwise poorly soluble. The carbonate product was primarily calcite (99.5%) with traces of quartz (0.5%). Calcite was the only CaCO3 polymorph obtained...

  4. Alterations of lead speciation by sulfate from addition of flue gas desulfurization gypsum (FGDG) in two contaminated soils

    This is the first study to evaluate the potential application of FGDG as an in situ Pb stabilizer in contaminated soils with two different compositions and to explain the underlying mechanisms. A smelter Pb contaminated soil (SM-soil), rich in ferrihydrite bound Pb (FH-Pb), ceru...

  5. Response of soybean and corn to soil mechanical intervention and agricultural gypsum application to the soil surface

    Lucindo Somavilla; Marlo Adriano Bison Pinto; Claudir José Basso; Clovis Orlando Da Ros; Vanderlei Rodrigues da Silva; Thiarles Brun; Antônio Luis Santi


    ...; however, crop responses to its application are contradictory. Studies have shown that the physical effects of soil mechanical intervention is short-lasting and has little impact on grain yield...

  6. Alterations of lead speciation by sulfate from addition of flue gas desulfurization gypsum (FGDG) in two contaminated soils

    This is the first study to evaluate the potential application of FGDG as an in situ Pb stabilizer in contaminated soils with two different compositions and to explain the underlying mechanisms. A smelter Pb contaminated soil (SM-soil), rich in ferrihydrite bound Pb (FH-Pb), ceru...

  7. Study of Compounded Water Repellent Gypsum Agent%复合型石膏防水剂的研究

    关瑞芳; 隋肃; 李建权; 葛曷一; 李国忠



  8. Study of compounded gypsum water repellent agent%复合型石膏防水剂的研究

    张国辉; 尹斫; 罗萍; 李国忠



  9. The use of gypsum mining by-product and lime on the engineering properties of compressed earth blocks

    Eliana Rocío Jaramillo-Pérez


    Full Text Available Las desventajas de los bloques de tierra comprimida son sus baj as propiedades mecánicas y resistencia al daño al agua. Por lo tanto, su uso es vulnerable al deterioro y requiere cuidado y mantenimien to, dependiendo del grado de estabilización y compactación del suelo arcilloso. Residuos de minería del yeso y cal se utilizaron com o estabilizantes para mejorar las propiedades de estos material es de construcción. Resistencia a compresión y flexión, ablandamiento en agua, retracción por secado y peso unitario se determinaron . La resistencia aumento con la adición de residuo de minería. La re sistencia al ablandamiento en agua fue mayor con 25% de residuo de minería. La contracción por secado disminuyo con el aumento del contenido de residuo de minería. El peso unitario seco no esta ba en los estándares recomendados. Los resultados mostraron que los resid uos de minería del yeso pueden utilizarse como materiales alter nativos en la estabilización de bloques de tierra comprimida.

  10. The effect of repeated immersion of gypsum cast in sodium hypochlorite and glutaraldehyde on its physical properties: An in vitro study

    Rachuri Narendra Kumar


    Full Text Available Background: One method used to disinfect a dental cast is immersion in a disinfecting solution. Repeated immersion of a cast in disinfectant may affect its physical properties. Purpose: The purpose of this study was to evaluate the changes in dimensional accuracy and hardness of the dental casts as a result of repeated disinfection in 0.525% sodium hypochlorite and 2% glutaraldehyde solutions. Materials and Methods: Sixty specimens were made of type III dental stone. Twenty specimens were immersed in slurry, a supernatant solution of calcium sulfate in distilled water (control casts, 20 specimens in 0.525% sodium hypochlorite, and 20 specimens in 2% glutaraldehyde solutions for 30 min and air dried for 24 h. This process was repeated for 7 times for testing. Linear dimensional change and hardness were determined according to American National Standards Institute/American Dental Association (ANSI/ADA standards. The data were analyzed using two-way analysis of variance. Results: For specimens prepared with type III stones, treatment was by immersion in slurry (group I - control casts, and by immersion in 0.525% sodium hypochlorite (group II - test group 1 and in 2% glutaraldehyde solution (group III - test group 2. The specimens treated with sodium hypochlorite and glutaraldehyde showed more linear dimensional change compared to the specimens treated in slurry. However, the difference between test casts and control casts was significant. But the difference between the two test groups was not significant. Both the test groups showed decrease in hardness of the specimens compared to that specimens in control group. But the difference between two test groups was not significant in hardness.However,the values remained close to ANSI/ADA standards. Conclusion: The results demonstrated that repeated immersion of type III dental stone specimens in slurry with distilled water, 0.525% sodium hypochlorite and 2% glutaraldehyde, along with drying in air, caused a significant increase in linear dimension and a significant decrease in hardness.

  11. Best Management Practices to Prevent and Control Hydrogen Sulfide and Reduced Sulfur Compound Emissions at Landfills That Dispose of Gypsum Drywall

    Hydrogen sulfide (H2S) gas can be emitted from both construction and demolition (C&D) debris and municipal solid waste (MSW) landfills. H2S emissions may be problematic at a landfill as they can cause odor, impact surrounding communities, cause wear or dama...

  12. Production development and utilization of Zimmer Station wet FGD by-products. Final report. Volume 3, Product development of gypsum, Phase 1

    Smith, Kevin [Dravo Technology Center, Pittsburgh, PA (United States); Beeghly, Joel H. [Dravo Technology Center, Pittsburgh, PA (United States)


    In the way of background information about 30 electric utility units with a combined total of 15,000 MW utilize magnesium enhanced lime flue gas desulfurization (FGD) systems. The first generation process begun in 1973, called the Thiosorbic® Process, was a technical breakthrough that offered significantly improved operating and performance characteristics compared with competing FGD technologies. The process is described as Flow Diagram "A" in Figure 1. A disadvantage of this and other inhibited or natural oxidation wet FGD systems is the capital and operating cost associated with landfill disposal of the calcium sulfite based solids. Fixation to stabilize the sludge solids for compunction in a landfill also consumes fly ash that otherwise may be marketable.

  13. G-P Gypsum Corporation, Order Granting in Part and Denying in Part Petition to Object to a Title V Permit

    This document may be of assistance in applying the Title V air operating permit regulations. This document is part of the Title V Petition Database available at Some documents in the database are a scanned or retyped version of a paper photocopy of the original. Although we have taken considerable effort to quality assure the documents, some may contain typographical errors. Contact the office that issued the document if you need a copy of the original.

  14. Assessment of dissolved-solids loading to the Colorado River in the Paradox Basin between the Dolores River and Gypsum Canyon, Utah

    Shope, Christopher L.; Gerner, Steven J.


    Salinity loads throughout the Colorado River Basin have been a concern over recent decades due to adverse impacts on population, natural resources, and regional economics. With substantial financial resources and various reclamation projects, the salt loading to Lake Powell and associated total dissolved-solids concentrations in the Lower Colorado River Basin have been substantially reduced. The Colorado River between its confluence with the Dolores River and Lake Powell traverses a physiographic area where saline sedimentary formations and evaporite deposits are prevalent. However, the dissolved-solids loading in this area is poorly understood due to the paucity of water-quality data. From 2003 to 2011, the U.S. Geological Survey in cooperation with the U.S. Bureau of Reclamation conducted four synoptic sampling events to quantify the salinity loading throughout the study reach and evaluate the occurrence and impacts of both natural and anthropogenic sources. The results from this study indicate that under late-summer base-flow conditions, dissolved-solids loading in the reach is negligible with the exception of the Green River, and that variations in calculated loads between synoptic sampling events are within measurement and analytical uncertainties. The Green River contributed approximately 22 percent of the Colorado River dissolved-solids load, based on samples collected at the lower end of the study reach. These conclusions are supported by water-quality analyses for chloride and bromide, and the results of analyses for the stable isotopes of oxygen and deuterium. Overall, no significant sources of dissolved-solids loading from tributaries or directly by groundwater discharge, with the exception of the Green River, were identified in the study area.

  15. 3D numerical analyses for the quantitative risk assessment of subsidence and water flood due to the partial collapse of an abandoned gypsum mine.

    Castellanza, R.; Orlandi, G. M.; di Prisco, C.; Frigerio, G.; Flessati, L.; Fernandez Merodo, J. A.; Agliardi, F.; Grisi, S.; Crosta, G. B.


    After the abandonment occurred in the '70s, the mining system (rooms and pillars) located in S. Lazzaro di Savena (BO, Italy), grown on three levels with the method rooms and pillars, has been progressively more and more affected by degradation processes due to water infiltration. The mine is located underneath a residential area causing significant concern to the local municipality. On the basis of in situ surveys, laboratory and in situ geomechanical tests, some critical scenarios were adopted in the analyses to simulate the progressive collapse of pillars and of roofs in the most critical sectors of the mine. A first set of numerical analyses using 3D geotechnical FEM codes were performed to predict the extension of the subsidence area and its interaction with buildings. Secondly 3D CFD analyses were used to evaluated the amount of water that could be eventually ejected outside the mine and eventually flooding the downstream village. The predicted extension of the subsidence area together with the predicted amount of the ejected water have been used to design possible remedial measurements.

  16. Application of Microwave Determination of Calcium Sulphate in Dry Phosphorus Gypsum%微波测定干料磷石膏中硫酸钙的应用

    彭桦; 周琼波; 杨稳权; 何宾宾; 韩增辉; 赵智波


    Dry phosphogypsum used specific digestion solution with microwave digestion to produce barium sulfate, the precipitation used glass sand core crucible vacuum filtering and reoccupy microwave constant for heavy precipitation. Obtained the experimental data, glass sand core crucible was low cost, using biodegradable poly epoxy succinic acid PESA ( salt) for soaking and washing, the recycling of glass sand core crucible was realized, the method was simple, analysis cycle was short, with energy saving and easy to operate, cheap instrument repairing, it was easy to promote.%干料磷石膏用特定的消解液微波消解,生成硫酸钡沉淀用玻璃砂芯坩埚负压抽滤,再用微波恒重沉淀,得出实验数据,玻璃砂芯坩埚用成本低、可降解的聚环氧琥珀酸PESA (盐)浸泡洗涤,实现了玻璃砂芯坩埚的再生利用,方法简便、分析周期短、节能易操作,仪器廉价易修,便于推广。

  17. Changes in mesophyll element distribution and phytometabolite contents involved in fluoride tolerance of the arid gypsum-tolerant plant species Atractylis serratuloides Sieber ex Cass. (Asteraceae).

    Boukhris, Asma; Laffont-Schwob, Isabelle; Rabier, Jacques; Salducci, Marie-Dominique; El Kadri, Lefi; Tonetto, Alain; Tatoni, Thierry; Chaieb, Mohamed


    Atractylis serratuloides is an abundant native spiny species that grows in the surroundings of superphosphate factories in Tunisia. This plant species is adapted to arid environments and tolerates a high level of fluoride pollution in soils. The aim of this study was to better understand the physiological mechanisms of fluoride tolerance of this species, comparing the fluoride-contaminated sites of Gabes and Skhira with the reference site of Smara. Results demonstrated the involvement of leaf element and phytometabolite balances in the in situ response of A. serrulatoides to fluoride. Calcium, sulphur and magnesium were differently distributed between the sites of Gabes and Smara in all plant organs. No specific tissue fluorine accumulation in root, stem and leaf, even in the most contaminated site at Gabes, was detected by EDAX mapping. Lower anthocyan and flavonol levels but enhanced nitrogen balance index were found in A. serrulatoides leaves from Gabes compared to the two other sites. A. serratuloides appeared as a fluoride excluder and its tolerance involved calcium interactions with fluoride. Moreover, an occurrence of dark septate endophytes and arbuscular mycorhizal fungi in root systems of A. serratuloides was reported for the first time, and these symbioses were present but low at all sites. We suggest the use of this plant species for fluoride-polluted soil stabilization.

  18. Mercury Removal, Methylmercury Formation, and Sulfate-Reducing Bacteria Profiles in Wetland Mesocosms Containing Gypsum-Amended Sediments and Scirpus californicus

    King, J.K.


    A pilot-scale model was constructed to determine if a wetland treatment system (WTS) could effectively remove low-level mercury from an outfall located at the Department of Energy's Savannah River Site.

  19. Effect of broiler litter ash and flue gas desulfurization gypsum on yield, calcium, phosphorus, copper, iron, manganese and zinc uptake by peanut

    Peanut (Arachis hyogaea) is an important oil seed crop that is grown as a principle source of edible oil and vegetable protein. Over 1.6 million acres of peanuts were planted in the United States during 2012. Peanuts require large amounts of calcium (Ca) and phosphorus (P). In 2010, over 10 milli...

  20. Geoelectrical Characterization of Sulphate Rocks

    Guinea Maysounave, Ander


    [eng] Gypsum rocks are widely exploited in the world as industrial minerals. The purity of the gypsum rocks (percentage in gypsum mineral –CaSO4•2H2O- in the whole rock) is a critical factor to evaluate the potential exploitability of a gypsum deposit. It is considered than purities higher than 80% in gypsum are required to be economically profitable. Gypsum deposits have been studied with geoelectrical methods; a direct relationship between the electrical resistivity values of the gypsum roc...

  1. Drug: D01728 [KEGG MEDICUS

    Full Text Available D01728 Crude, Drug Gypsum (JP16); Gypsum fibrosum (TN) Calcium sulfate [DR:D09201],...ponent: Calcium sulfate [DR:D09201] Therapeutic category of drugs in Japan [BR:br08301] 5 Crude dr...ugs and Chinese medicine formulations 51 Crude drugs 510 Crude drugs 5100 Crude drugs D0172...8 Gypsum (JP16) Traditional Chinese Medicine in Japan [BR:br08304] Crude Drugs Drugs for clearing heat Drugs... for clearing heat D01728 Gypsum; Calcium sulfate; Gypsum fibrosum Crude drugs [BR:br08305] Others Minerals D01728 Gypsum PubChem: 7848791 ...

  2. 掺硫化碱渣和磷石膏的粉煤灰空心砌块研制%Development of fly ash hollow block mixed with sulfide alkaline slag and phosphorous-gypsum




  3. 碳酸钙与石膏对土壤磷及溶解有机碳淋溶的影响%Effects of CaCO3 and Gypsum on leaching of phosphorus and dissolved organic carbon in soil

    郭堃梅; 池宝亮; 黄学芳; David Chittleborough



  4. Design and application on the gypsum embedded filler cast-in-situ concrete hollow floor%石膏空腔模填充混凝土空心楼盖研制及应用

    肖良锦; 曹磊芳; 高朋朋


    A new type of cast-in-situ concrete hollow floor is put forward.The characteristics of this floor are introduced from the aspects of processing, designing, oonstruction, structural, economic, application and so on.The results show that there are many advantages such as economical, practical, easy construction etc about this system.So this environmental protection and energy hollow floor system is worth using wildly.%提出了一种新型现浇混凝土空心楼盖,从加工、研制、施工、结构、经济、运用等方面介绍了这种新型楼盖的特性.研究与运用结果表明,该楼盖体系具有经济、实用、易施工、结构性能好等诸多优点,是值得推广的环保节能型空心楼盖体系.

  5. 快速加热型石膏包埋料对铸造精度影响的研究%Evaluation of cast accuracy for rapid burnout type gypsum-bonded investment

    董宏伟; 石四箴; 陈克恭; 小园凯夫


    目的 研究快速加热型石膏包埋料包埋后放置时间对其膨胀及铸件铸造精度的影响.方法 选用传统型石膏包埋料CRISTOBALITE P(CBP)、快速加热型石膏包埋料CRISTOBALITE PF(CBPF)和CRISTQUICK 20(CQ).根据包埋料类型及包埋后放置时间不同分组为CBP、CBPF-30、CBPF-60、CQ-20、CQ-40、CQ-60.分别测定各组包埋料的硬化膨胀率和热膨胀率.以六棱柱形状蜡型为铸件原型,应用各组包埋料包埋铸造,测量各组所得铸件的尺寸变化率.结果 CBPF-30组、CQ-20组的硬化膨胀率和热膨胀率均小于CBP组.随着包埋后放置时间的延长,CBPF和CQ各组的硬化膨胀率明显增大,热膨胀率逐渐减小.CBPF-30组和CQ-20组包埋料所得铸件的收缩率均大于CBP组.CBPF两组所得铸件的尺寸变化率无差别,CQ3组所得铸件的尺寸变化率无差别.结论 在一定限度内适当延长快速加热型石膏包埋料包埋后放置时间对铸件的铸造精度无明显影响.


    卡马·嘉利; 刘伟



  7. 纤维补强增韧耐水性复合石膏硬化体的开发%Development of fiber reinforced toughen water resistant gypsum based composites

    卞敬玲; 大滨嘉彦; 林志翔



  8. One Case Study about BIAN Song-jing's Treatment to Allergy Vasculitis by High Dosage of Shigao (Gypsum)%卞嵩京以大剂石膏治疗变应性血管炎一案




  9. 磷石膏处置标准与磷石膏堆场处置设想%Disposal standard of phosphogypsum and tentative disposal ideas for the gypsum stack

    储学群; 张国兴; 童小祥



  10. Simultaneous SO/sub 2//NO/sub x/ separation in the aqueous phase, with gypsum production and SO/sub 2/ release in the pre-washing phase

    Hoelter, H.; Igelbuescher, H.; Gresch, H.; Dewert, H.


    This flue gas purification method first purifies the crude gas from HCl and HF in the prescrubber and from SO/sub 2/ and/or NO/sub x/ in the main scrubber. The CaSO/sub 3//CaSO/sub 4/ product occurring in the main scrubber is, according to invention, pumped through a pipe into the prescrubber. In this process CaSO/sub 3/ is oxidized into CaSO/sub 4/ because of the high quantity of excess atmospheric oxygen in the crude gas. The pH value of the scrubber solution in the prescrubber should be between 2 and 2.5. A separate oxidation stage is saved by this method.

  11. Effects of Different Adding Methods of Citric Acid on the Properties of Flue Gas Desulphurization Gypsum%柠檬酸添加方式对脱硫石膏性能影响

    姜伟; 范立瑛; 刘健飞; 王志



  12. Application of Lead Sintering Stack Gases' Desulfuration by Calciun Sulphite-gypsum%亚硫酸钙——石膏法在铅烧结烟气脱硫中的应用

    吴建国; 万小山; 谢吉生; 王水金



  13. 《伤寒杂病论》中麻黄与石膏配伍规律探讨%Exploration on the Compatibility of Cow-bezoare and Gypsum in the "Treatise on Febrile and Miscellaneous Diseases"

    徐伟辉; 龚高柏


    @@ 张仲景载方314首,其中麻黄、石膏同用之方有麻杏石甘汤、大青龙汤、桂枝二越婢一汤、麻黄升麻汤、越婢汤、越婢加半夏汤、越婢加术汤、小青龙加石膏汤、麻黄厚朴汤等9方.纵观仲景将辛温之麻黄与甘寒之石膏同用,不外乎治疗表寒里热证、上寒下热证、寒轻热重证、寒重热轻证等,均系寒热错杂之证.然细揣摩,由于方中麻黄、石膏用量不同,君臣佐使作用不一,故其功效迥异.笔者不揣浅陋,特作探讨如下.

  14. 利用煤矸石、工业石膏煅烧阿利特-硫铝酸盐水泥熟料%Using coal gangue and industry gypsum as raw materials to produce alite-sulphoaluminate cement clinker




  15. 高贝利特硫铝酸盐水泥最佳石膏掺量的研究%Optimum Addition of Gypsum in High Belite Sulphoaluminate Cement

    兰明章; 张海文; 张振秋; 陈智丰



  16. The production of sulphoaluminate cement clinker with phosphorus gypsum as raw material%磷石膏作原料试生产硫铝酸盐水泥熟料

    李德栋; 毕利坤; 王晓华



  17. Study on Hydration and Hardening of Duplex Gypsum Binder of Hemihydrite Phosphogypsum and Anhydrite Phosphogypsum%半水/无水磷石膏复相胶凝材料水化硬化特性研究

    杨成军; 杨敏; 曹建新


    采用半水磷石膏与无水磷石膏复配制备复相磷石膏胶凝材料,通过测试复相磷石膏的凝结时间、强度性能和水化温升,结合X射线衍射(XRD)和扫描电镜(SEM)技术研究复相磷石膏水化硬化特性。结果表明,半水磷石膏激发无水磷石膏水化,使其水化放热加快,凝结时间缩短;无水磷石膏延缓半水磷石膏凝结硬化,凝结时间延长,水化放热减缓;与纯半水、无水磷石膏相比,复相磷石膏晶体形貌致密程度高,孔隙率低,硬化体强度较好。%The hydration and hardening characteristics of duplex phosphogypsum(DPG) prepared by hemihydrate phosphogypsum(HPG) and anhydrite phosphogypsum(APG) were studied through investigating the setting time, strength properties and temperature rise of hydration and by analyzing the XRD spectrum and SEM graphs of the prepared DPG. The results show that APG was activated by HPG, and the heat evolution was accelerated. And the hydration of HPG was retarded by APG, leading to retardation of the heat evolution. Comparing with pure hemihydrates or anhydrite phosphogypsum, the duplex phosphogypsum binder has higher compactness of crystal morphology, lower porosity and better strength of hardened paste.


    杜谦; 吴少华; 朱群益; 秦裕琨


    A study on non-catalytic oxidation kinetics of calcium sulfite is presented under typical conditions of wet flue gas desulfurization (FGD)in this paper. A laboratory-scale mechanically stirred tank reactor is used with continuous feed of both gas and liquid phase. The results show that increasing CaSO3 load from a lower value, the reaction rate increases and is limited by solid sulfite dissolution. The oxidation rate limitation is observed at loads exceeding certain concentration. The rate limitation is possibly caused by solid sulfite solubility or oxygen gas-liquid diffusion. The experimental conclusions are useful for design and operation of the holding tank in forced-oxidation wet FGD.

  19. Uncertainty Evaluation of Analytical Results for Carbonate in Natural Gypsum