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Sample records for activated fly ash

  1. Fly ash effects. II. The active effect of fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Aiqin Wang; Chengzhi Zhang; Wei Suna [Southeast University, Nanjing (China). Department of Materials Science and Engineering

    2004-11-01

    This paper examines the method for determining the hydration degree of cement clinker and the pozzolanic reaction degree of fly ash in the system of cement and fly ash. In the base, the active effect of fly ash is studied. The studied results show that the active effect includes two aspects: (1) Fly ash has stronger pozzolanic activity and can react with Ca(OH)2, and (2) it can promote the hydration of cement. When the content of fly ash is less, its pozzolanic activity can exert well, but its promoting role to the hydration of cement is weaker. When the content of fly ash is more, it is less than its pozzolanic activity can be used, but its promoting role to the hydration of cement is stronger.

  2. FLEXURAL BEHAVIOUR OF ACTIVATED FLY ASH CONCRETE

    Directory of Open Access Journals (Sweden)

    SUNILAA GEORGE

    2011-10-01

    Full Text Available Cement concrete is the most widely used construction material in many infrastructure projects. The development and use of mineral admixture for cement replacement is growing in construction industry mainly due to the consideration of cost saving, energy saving, environmental production and conservation of resources. Present study is aimed at replacing cement in concrete with activated fly ash. The paper highlights the chemical activation of low calcium fly ash using CaO and Na2SiO3 in the ratio 1:8 for improving the pozzolanic properties of fly ash .The investigation deals with the flexural behavior of beams using chemically activated fly ash at various cement replacement levels of 10%, 20%, 30%, 40%, 50%, and 60% with water cement ratio 0.45.The results are compared with OPC and Activated Fly ash at the same replacement levels.

  3. Surface Modification of Fly Ash for Active Catalysis

    OpenAIRE

    Deepti Jain; Renu Hada; Ashu Rani

    2013-01-01

    Fly ash based effective solid base catalyst (KF/Al2O3/fly ash473, KF/Al2O3/fly ash673, and KF/Al2O3/fly ash873) was synthesized by loading KF over chemically and thermally activated fly ash. The chemical activation was done by treating fly ash with aluminum nitrate via precipitation method followed by thermal activation at 650°C to increase the alumina content in fly ash. The increased alumina content was confirmed by SEM-EDX analysis. The alumina enriched fly ash was then loaded with KF (10...

  4. Characteristic of elements in coal bottom ash and fly ash by instrumental neutron activation analysis (INAA)

    International Nuclear Information System (INIS)

    Coal-fired power plant and industrial stacks that using coal produce solid waste such as bottom ash and fly ash. Determination of elements in these wastes qualitatively and quantitatively is usually the first step taken for subsequent evaluation of the associated environmental and biological risks. In this study, the determination of trace elements in bottom ash and fly ash by instrumental neutron activation analysis was carried out. The samples were irradiated at rabbit facility in G.A. Siwabessy reactor with neutron flux ~ 1013 n.cm-2.s-1, and then counted by HPGe spectrometer gamma detector. The validation of method was performed by characterization of standard reference material (SRM) 1633b coal fly ash from National Institute of Standards and Technology (NIST). Some elements such as Al, As, Ce, Co, Cr, Cs, Fe, K, La, Mn, Na, Sc, Sm, Ti and V were detected in both samples. The concentration of environmentally toxic elements, As and Cr in bottom ash were 6.24 and 137.4 mg/kg, whereas in fly ash were 6.37 and 39.0 mg/kg respectively. Arsenic concentrations had been over the standard value based on PP no.85/1999. (author)

  5. Radon activity and exhalation rates in Indian fly ash samples

    International Nuclear Information System (INIS)

    Fly ash is the by-product of burnt coal which is naturally occurring radioactive material (NORM). Because of human activity and its use in manufacturing of bricks, sheets, cement, land filling etc. may present a radiation hazard to people and the environment. Thus, it is very important to carry out radioactivity measurements in fly ash from the health and hygiene point of view. In the present study, the activity concentrations of 238U, 232Th and 40K have been varied from 99 ± 2 to 203 ±4 Bq/kg, 145 ± 2 to 288 ± 4 Bq/kg, and 355 ± 5 to 516 ± 6 Bq/kg, respectively in various fly ash samples. The radium equivalent activity was varied from 317 to 614 Bq/kg, radon activity varied from 214 to 590 Bq/m3, radon exhalation rate varied from 7.8 to 21.6 inBqkg-1h-1 for mass exhalation rate and from 138 to 381 mBqm2h-1 for surface exhalation rate in the fly ash samples used in the present investigation. The absorbed dose varied from 143 to 277 nGyh-1, the indoor annual effective dose varied from 0.70 to 1.36 mSv and the outdoor annual effective dose varied from 0.17 to 0.34 mSv. In all the samples, the activity concentration of 238U, 232Th and 40K was found to be below the permissible levels. A strong positive correlation has been observed between uranium concentration, radon activity and radon exhalation rate. (author)

  6. THE INFLUENCE OF TEMPERATURE AND ADMIX- TURES ON ACTIVATION OF LOW CALCIUM FLY ASH

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    According to composition and structure properties of low calcium fly ash, the activation and reaction degree of fly ash-lime and fly ash-lime-gypsum system were studied in different alkali surroundings and temperatures by thermal-gravity analysis.The degree of reaction and pore structure analysis test results show that composite alkali play an important role in the activation and degree of reaction of fly ash at room temperature. But when increasing curing temperature, gypsum would play an important role in activation and hydration of fly ash.

  7. Magnesia Modification of Alkali-Activated Slag Fly Ash Cement

    Institute of Scientific and Technical Information of China (English)

    SHEN Weiguo; WANG Yiheng; ZHANG Tao; ZHOU Mingkai; LI Jiasheng; CUI Xiaoyu

    2011-01-01

    A new type of magnesia modification alkali-activated cement was prepared, the strength, setting time, shrinkage ratio and cracking behavior, as well as the composition and structure of the hydration product were investigated. The results indicate that the setting time of this cement is similar to that of the ordinary commercial cements; its strength reaches the standard of 42.5 degree cement, its cracking resistance has been remarkably improved because of the micro-aggregate effect of fly ash and shrinkage compensating of magnesia.

  8. Synthesis and sintering of high-temperature composites based on mechanically activated fly ash

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    Terzić A.

    2012-01-01

    Full Text Available Amount of fly ash which is and yet to be generated in the coming years highlights the necessity of developing new methods of the recycling where this waste can be reused in significant quantity. A new possibility for fly ash utilization is in high-temperature application (thermal insulators or/and refractory material products. As such, fly ash has to adequately answer the mechanical and thermal stability criteria. One of the ways of achieving it is by applying mechanical activation procedure on fly ash. In present study, fly ashes from two different power plants were mechanically activated in a planetary ball mill. Mechanically treated fly ashes were cemented with two different binders: standard Portland cement and high-aluminates cement. Physico-chemical analysis and investigation of mineralogical components of composites are emphasized, due to the changes occurred in fly ash during mechanical activation and sintering of composites. Macro-performance of the composites was correlated to the microstructure of fly ash studied by means of XRD and SEM analysis. Thermal stability of crystalline phases was investigated with DTA. Highlight was placed on determination of relationship between mechanically activated fly ash and obtained composites microstructure on one side and behavior of sintered composites on the other side. [Projekat Ministarstva nauke Republike Srbije, br. 172057, 45008 and a project F-198, financed by Serbian Academy of Sciences and Arts

  9. Effect of Steel Fiber on Alkali activated Fly Ash Concrete

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    S.L.Hake

    2016-05-01

    Full Text Available Concrete is the world’s most important Construction material so the demand of cement is increases. The production of cement is highly energy intensive & the production on one ton of cement liberates about one ton of CO2 to atmosphere. The contribution of cement industry to the greenhouse gas emission is estimated to be about 70% of the total green gas emission. Also it consumes large amount of natural resources. Hence it is essential to find alternative to cement. Geopolymer concrete is an innovative material in which the binder is produced but the reaction of an alkaline liquid with a source material that is rich in silica alumina. The present work deals with the result of the experimental investigation carried out on geopolymer concrete using steel fiber. The study analyses the effect of steel on compressive strength. Geopolymer concrete mixes were prepared using low calcium fly ash & activated by alkaline solution. (NaOH & Na2SiO3 with alkaline liquid to fly ash ratio of 0.35 Alkaline solution. Used for present study combination of sodium hydroxide & sodium silicate with ratio 2.5. The mix was designed for molarity of 16M & grade chosen for investigation was M30. Hooked end steel fiber . All tests were conducted according to IS-code procedure. The result for each variation are tabulated & discussed in details & some important conclusions are made.

  10. Synthesis of Zeolites by Alkaline Activation of Fly Ash

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In terms of mineral transformation, and chemical composition of acid-soluble component as a function of reaction time, the effect of alkaline solution on zeolite-like fly ash was studied by employing fly ash and NaOH solution as starting materials. When fly ash and 1€? 0mol/L NaOH solution were processed at 100℃ for 24h with 1:10 W/S rat io in a relatively closed system, powder XRD patterns of resulting pro ducts indicated the formation of various zeolites. Zeolite P crystalli zed early at low alkaline concentration, which was replaced then by ze olites X and A. At high concentration, hydroxy sodalite was the only n ew phase. Quartz, in fly ash and NaOH solution system, gradually disso lved, and mullite, however, remained stable. It was concluded that, wi th Al/Si and Na/Si finally reaching equilibrium in molar ratio, compos ition of starting mixtures affects the crystallization of zeolite from fly ash.

  11. Preparation of Fly ash Based Adsorbents for Removal Active Red X-3B from Dying Wastewater

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    Li Jinping

    2016-01-01

    Full Text Available Fly ash with a large number of active sites can occur with the adsorbent chemical and physical adsorption, and therefore have a strong adsorption capacity. The original fly ash and raw fly ash compared to the physical and chemical properties to a significant change. On the fly ash in industrial water treatment application were outlined. The purpose is to focus on the modification methods of fly ash and comparison of raw fly ash and fly ash in the effect of dyeing wastewater. Single factor test method; select the appropriate modifier to study the dosage, pH, stirring time on the modification of adsorption properties of fly ash before and after. The results showed that the modified fly ash was better than the adsorption. Greatly improves on active red X-3B dye wastewater removal capacity, pH = 5, 6, dosage is 5g / L, the mixing time is 30min, COD removal rate reached 73.07%. This modified material can be used as adsorbent for pre-treating dying wastewater.

  12. Instrumental neutron activation analysis of fly ash, aerosols and hair

    International Nuclear Information System (INIS)

    Samples of coal, slag, emissions retained on the separating devices, fly ash, aerosols and hair taken in the area of coal-fired power plant were analyzed by means of instrumental neutron activation analysis. 13 to 23 elements were determined in the samples. The data obtained for emissions and aerosols were further evaluated by calculation of enrichment factors, correlation coefficients and by the ratio matching method. The concentrations of elements determined in the hair of the exposed group were compared with data of control and so called ''out control'' groups as well as with recent data found for hair in other countries. It can be seen from the results that arsenic is the most serious pollutant in the area. (author)

  13. Steel passive state stability in activated fly ash mortars

    Directory of Open Access Journals (Sweden)

    Fernández-Jiménez, A.

    2010-12-01

    Full Text Available The present study explores the behaviour of structural steel embedded in Portland cement (OPC mortars and NaOH- and NaOH-waterglass-activated fly ash, in the presence and absence of 2 % Cl- (CaCl2. Variations were determined in the corrosion potential (Ecorr, linear polarization resistance (Rp and corrosion current density (icorr under different environmental conditions (90 days at 95 % relative humidity (RH, 30 days at ≈ 30 % RH, 760 days at ≈ 95 % RH. In the absence of Cl-, fly ash mortars were able to passivate steel reinforcement, although the stability of the passive state in changing environmental conditions was found to depend heavily on the activating solution used. Steel corrosion in the presence of 2 % Cl- was observed to be similar to the corrosion reported for the material in OPC mortars.

    En el presente trabajo se estudia el comportamiento del acero estructural embebido en morteros de cemento Pórtland (OPC y de cenizas volantes activadas con NaOH y una mezcla de NaOH y waterglass, en ausencia y en presencia de un 2% de Cl- (CaCl2. Se determino la evolución del potencial de corrosión (Ecorr, la resistencia de polarización lineal (Rp y la intensidad de corrosión (icorr, variando las condiciones ambientales (90 días al 95% de humedad relativa (HR-30 días a ≈ 30% HR- 760 días a ≈ 95% HR. En ausencia de Cl- los morteros de cenizas volantes activadas pueden pasivar los refuerzos de acero, si bien la estabilidad del estado pasivo ante cambios en las condiciones ambientales parece mostrar una fuerte dependencia de la solución activadora empleada. En presencia de un 2% de Cl- los aceros se corroen mostrando en comportamiento similar al observado en morteros en base OPC.

  14. Fly ash carbon passivation

    Science.gov (United States)

    La Count, Robert B; Baltrus, John P; Kern, Douglas G

    2013-05-14

    A thermal method to passivate the carbon and/or other components in fly ash significantly decreases adsorption. The passivated carbon remains in the fly ash. Heating the fly ash to about 500 and 800 degrees C. under inert gas conditions sharply decreases the amount of surfactant adsorbed by the fly ash recovered after thermal treatment despite the fact that the carbon content remains in the fly ash. Using oxygen and inert gas mixtures, the present invention shows that a thermal treatment to about 500 degrees C. also sharply decreases the surfactant adsorption of the recovered fly ash even though most of the carbon remains intact. Also, thermal treatment to about 800 degrees C. under these same oxidative conditions shows a sharp decrease in surfactant adsorption of the recovered fly ash due to the fact that the carbon has been removed. This experiment simulates the various "carbon burnout" methods and is not a claim in this method. The present invention provides a thermal method of deactivating high carbon fly ash toward adsorption of AEAs while retaining the fly ash carbon. The fly ash can be used, for example, as a partial Portland cement replacement in air-entrained concrete, in conductive and other concretes, and for other applications.

  15. Fly ash quality and utilization

    Energy Technology Data Exchange (ETDEWEB)

    Barta, L.E.; Lachner, L.; Wenzel, G.B. [Inst. for Energy, Budapest (Hungary); Beer, M.J. [Massachusetts Inst. of Technology, Cambridge, MA (United States)

    1995-12-01

    The quality of fly ash is of considerable importance to fly ash utilizers. The fly ash puzzolanic activity is one of the most important properties that determines the role of fly ash as a binding agent in the cementing process. The puzzolanic activity, however is a function of fly ash particle size and chemical composition. These parameters are closely related to the process of fly ash formation in pulverized coal fired furnaces. In turn, it is essential to understand the transformation of mineral matter during coal combustion. Due to the particle-to-particle variation of coal properties and the random coalescence of mineral particles, the properties of fly ash particles e.g. size, SiO{sub 2} content, viscosity can change considerably from particle to particle. These variations can be described by the use of the probability theory. Since the mean values of these randomly changing parameters are not sufficient to describe the behavior of individual fly ash particles during the formation of concrete, therefore it is necessary to investigate the distribution of these variables. Examples of these variations were examined by the Computer Controlled Scanning Electron Microscopy (CCSEM) for particle size and chemical composition for Texas lignite and Eagel Butte mineral matter and fly ash. The effect of combustion on the variations of these properties for both the fly ash and mineral matter were studied by using a laminar flow reactor. It is shown in our paper, that there are significant variations (about 40-50% around the mean values) of the above-listed properties for both coal samples. By comparing the particle size and chemical composition distributions of the mineral matter and fly ash, it was possible to conclude that for the Texas lignite mineral matter, the combustion did not effect significantly the distribution of these properties, however, for the Eagel Butte coal the combustion had a major impact on these mineral matter parameters.

  16. Activation of fly ashes by the high temperature and high alkalinity in ASR tests

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    High temperature and high alkalinity are typical testing conditions to accelerate the appraisal process of the suppressing effect of fly ashes on alkali silica reaction(ASR),but the reaction mechanism of fly ashes would be quite different under such conditions compared to the normal condition of temperature and alkalinity.To make a reasonable analysis of the suppressing effect of fly ashes,13 types of fly ashes were tested in this paper by both the accelerated mortar bar test method and the 60°C accelerated concrete prism test method.The results showed that the effect of fly ashes would be magnified under the condition of high temperature and high alkalinity.The XRD analysis showed that all the phases of fly ash could react with the hot alkaline solution except for mullite and a small amount of quartz.Fly ash could be significantly activated by the 80°C 1 mol/L NaOH solution,and form mainly C-S-H phase and P type zeolite,but its effect on inhibiting ASR was exaggerated then.According to the mortar strength test and the ASR suppressing test results,C-S-H phase contributed to mortar strength,but its amount did not decide the ASR suppressing effect of fly ash.

  17. Effect of fly ash amendment on metolachlor and atrazine degradation and microbial activity in two soils.

    Science.gov (United States)

    Ghosh, Rakesh Kumar; Singh, Neera; Singh, Shashi Bala

    2016-08-01

    The study reports the effect of Inderprastha (IP) and Badarpur (BP) fly ashes on degradation of metolachlor and atrazine in Inceptisol and Alfisol soils. Metolachlor dissipated at faster rate in Alfisol (t1/2 8.2-8.6 days) than in Inceptisol (t1/2 13.2-14.3 days). The fly ashes enhanced the persistence of metolachlor in both the soils; however, the extent of effect was more in Inceptisol (t1/2 16.6-33.8 days) than Alfisol (t1/2 8.4-12 days) and effect increased with fly ash dose. 2-Ethyl-6-methylacetanilide was detected as the only metabolite of metolachlor. Atrazine was more persistent in flooded soils (t1/2 10.8-20.3 days) than nonflooded soils (t1/2 3.7-12.6 days) and fly ash increased its persistence, but effect was more pronounced in the flooded Inceptisol (t1/2 23.7-31 days) and nonflooded Alfisol (t1/2 6.3-10.1 days). Increased herbicide sorption in the fly ash-amended soils might have contributed to the increased pesticide persistence. The IP fly ash inhibited microbial biomass carbon at 5 % amendment levels in both the soils, while BP fly ash slightly increased microbial biomass carbon (MBC) content. Dehydrogenase activity was inhibited by both fly ashes in both the soils with maximum inhibition observed in the IP fly ash-amended Alfisol. No significant effect of fly ash amendment was observed on the fluorescein diacetate activity. PMID:27456695

  18. INVESTIGATION OF FLY ASH AND ACTIVATED CARBON OBTAINED FROM PULVERIZED COAL BOILERS

    Energy Technology Data Exchange (ETDEWEB)

    Edward K. Levy; Christopher Kiely

    2005-11-01

    One of the techniques for Hg capture in coal-fired boilers involves injection of activated carbon (AC) into the boiler downstream of the air preheater. Hg is adsorbed onto the AC particles and fly ash, which are then both removed in an electrostatic precipitator or baghouse. This project addresses the issues of Hg on activated carbon and on fly ash from a materials re-use point of view. It also addresses the possible connection between SCR reactors, fly ash properties and Hg capture. The project is determining the feasibility of separating AC from fly ash in a fluidized bed and of regenerating the separated AC by heating the AC to elevated temperatures in a fluidized bed. The temperatures needed to drive off the Hg from the ash in a fluidized bed are also being determined. Finally, samples of fly ash from power plants with SCR reactors for NO{sub x} control, are being analyzed to determine the effect of SCR on the ash.

  19. Investigation of Fly Ash and Activated Carbon Obtained from Pulverized Coal Boilers

    Energy Technology Data Exchange (ETDEWEB)

    Edward K. Levy; Christopher Kiely; Zheng Yao

    2006-08-31

    One of the techniques for Hg capture in coal-fired boilers involves injection of activated carbon (AC) into the boiler downstream of the air preheater. Hg is adsorbed onto the AC particles and fly ash, which are then both removed in an electrostatic precipitator or baghouse. This project addressed the issues of Hg on activated carbon and on fly ash from a materials re-use point of view. It also addressed the possible connection between SCR reactors, fly ash properties and Hg capture. The project has determined the feasibility of separating AC from fly ash in a fluidized bed and of regenerating the separated AC by heating the AC to elevated temperatures in a fluidized bed. The temperatures needed to drive off the Hg from the ash in a fluidized bed have also been determined. Finally, samples of fly ash from power plants with SCR reactors for NO{sub x} control have been analyzed in an effort to determine the effects of SCR on the ash.

  20. Toxicity mitigation and solidification of municipal solid waste incinerator fly ash using alkaline activated coal ash.

    Science.gov (United States)

    Diaz-Loya, E Ivan; Allouche, Erez N; Eklund, Sven; Joshi, Anupam R; Kupwade-Patil, Kunal

    2012-08-01

    Municipal solid waste (MSW) incineration is a common and effective practice to reduce the volume of solid waste in urban areas. However, the byproduct of this process is a fly ash (IFA), which contains large quantities of toxic contaminants. The purpose of this research study was to analyze the chemical, physical and mechanical behaviors resulting from the gradual introduction of IFA to an alkaline activated coal fly ash (CFA) matrix, as a mean of stabilizing the incinerator ash for use in industrial construction applications, where human exposure potential is limited. IFA and CFA were analyzed via X-ray fluorescence (XRF), X-ray diffraction (XRD) and Inductive coupled plasma (ICP) to obtain a full chemical analysis of the samples, its crystallographic characteristics and a detailed count of the eight heavy metals contemplated in US Title 40 of the Code of Federal Regulations (40 CFR). The particle size distribution of IFA and CFA was also recorded. EPA's Toxicity Characteristic Leaching Procedure (TCLP) was followed to monitor the leachability of the contaminants before and after the activation. Also images obtained via Scanning Electron Microscopy (SEM), before and after the activation, are presented. Concrete made from IFA, CFA and IFA-CFA mixes was subjected to a full mechanical characterization; tests include compressive strength, flexural strength, elastic modulus, Poisson's ratio and setting time. The leachable heavy metal contents (except for Se) were below the maximum allowable limits and in many cases even below the reporting limit. The leachable Chromium was reduced from 0.153 down to 0.0045 mg/L, Arsenic from 0.256 down to 0.132 mg/L, Selenium from 1.05 down to 0.29 mg/L, Silver from 0.011 down to .001 mg/L, Barium from 2.06 down to 0.314 mg/L and Mercury from 0.007 down to 0.001 mg/L. Although the leachable Cd exhibited an increase from 0.49 up to 0.805 mg/L and Pd from 0.002 up to 0.029 mg/L, these were well below the maximum limits of 1.00 and 5

  1. Rice husk ash as a source of silica in alkali-activated fly ash and granulated blast furnace slag systems

    OpenAIRE

    Mejía, J. M.; Puertas, F.

    2014-01-01

    [EN]This study assesses the viability of using an agro-industrial by-product, rice husk ash (RHA) from a Colombian rice company’s combustion facility, as a total replacement for the commercial sodium silicate ordinarily used in alkaliactivated binders. Fly ash (FA), granulated blast furnace slag (GBFS) and binary 50FA:50GBFS blended pastes were activated with a mix of sodium hydroxide and either sodium silicate or one of two types of RHA. The pastes were characterised ...

  2. Treatment of fly ash for use in concrete

    Science.gov (United States)

    Boxley, Chett; Akash, Akash; Zhao, Qiang

    2012-05-08

    A process for treating fly ash to render it highly usable as a concrete additive. A quantity of fly ash is obtained that contains carbon and which is considered unusable fly ash for concrete based upon foam index testing. The fly ash is mixed with an activator solution sufficient to initiate a geopolymerization reaction and for a geopolymerized fly ash. The geopolymerized fly ash is granulated. The geopolymerized fly ash is considered usable fly ash for concrete according to foam index testing. The geopolymerized fly ash may have a foam index less than 35% of the foam index of the untreated fly ash, and in some cases less than 10% of the foam index of the untreated fly ash. The activator solution may contain an alkali metal hydroxide, carbonate, silicate, aluminate, or mixtures thereof.

  3. Identifying glass compositions in fly ash

    Science.gov (United States)

    Aughenbaugh, Katherine; Stutzman, Paul; Juenger, Maria

    2016-01-01

    In this study, four Class F fly ashes were studied with a scanning electron microscope; the glassy phases were identified and their compositions quantified using point compositional analysis with k-means clustering and multispectral image analysis. The results showed that while the bulk oxide contents of the fly ashes were different, the four fly ashes had somewhat similar glassy phase compositions. Aluminosilicate glasses (AS), calcium aluminosilicate glasses (CAS), a mixed glass, and, in one case, a high iron glass were identified in the fly ashes. Quartz and iron crystalline phases were identified in each fly ash as well. The compositions of the three main glasses identified, AS, CAS, and mixed glass, were relatively similar in each ash. The amounts of each glass were varied by fly ash, with the highest calcium fly ash containing the most of calcium-containing glass. Some of the glasses were identified as intermixed in individual particles, particularly the calcium-containing glasses. Finally, the smallest particles in the fly ashes, with the most surface area available to react in alkaline solution, such as when mixed with portland cement or in alkali-activated fly ash, were not different in composition than the large particles, with each of the glasses represented. The method used in the study may be applied to a fly ash of interest for use as a cementing material in order to understand its potential for reactivity.

  4. Identifying glass compositions in fly ash

    Directory of Open Access Journals (Sweden)

    Katherine eAughenbaugh

    2016-01-01

    Full Text Available In this study, four Class F fly ashes were studied with a scanning electron microscope; the glassy phases were identified and their compositions quantified using point compositional analysis with k-means clustering and multispectral image analysis. The results showed that while the bulk oxide contents of the fly ashes were different, the four fly ashes had somewhat similar glassy phase compositions. Aluminosilicate glasses (AS, calcium aluminosilicate glasses (CAS, a mixed glass, and, in one case, a high iron glass were identified in the fly ashes. Quartz and iron crystalline phases were identified in each fly ash as well. The compositions of the three main glasses identified, AS, CAS, and mixed glass, were relatively similar in each ash. The amounts of each glass were varied by fly ash, with the highest calcium fly ash containing the most of calcium-containing glass. Some of the glasses were identified as intermixed in individual particles, particularly the calcium-containing glasses. Finally, the smallest particles in the fly ashes, with the most surface area available to react in alkaline solution, such as when mixed with portland cement or in alkali-activated fly ash, were not different in composition than the large particles, with each of the glasses represented. The method used in the study may be applied to a fly ash of interest for use as a cementing material in order to understand its potential for reactivity.

  5. An assessment of Mercury immobilisation in alkali activated fly ash (AAFA) cements.

    Science.gov (United States)

    Donatello, Shane; Fernández-Jiménez, Ana; Palomo, Angel

    2012-04-30

    This paper presents total and soluble Mercury contents for three coal fly ashes and alkali-activated fly ash (AAFA) cements consisting of 100% fly ash as starting material. To evaluate the potential of the AAFA cement matrix to immobilise Hg from an external source, another batch of cements, doped with 5000 mg/kg Hg as highly soluble HgCl(2), was prepared. The ashes and control AAFA cements complied with Mercury leaching criteria for non-hazardous wastes according to both TCLP and EN 12457 tests. Fly ash activated cements doped with 5000 mg/kg Hg and aged for 2 days immobilised 98.8-99.6% and 97.3-98.8% of Hg according to TCLP and EN 12457 tests respectively. Evidence from SEM-EDX suggests that Hg was immobilised by precipitation as highly insoluble HgS or Hg(2)S, although partial precipitation as less insoluble HgO or Hg silicates could not be entirely ruled out based on data presented. The results for Hg-doped cements contribute to the growing body of evidence that shows AAFA cement as a useful material for immobilizing elevated concentrations of toxic and hazardous elements. PMID:22341491

  6. Rice husk ash as a source of silica in alkali-activated fly ash and granulated blast furnace slag systems

    OpenAIRE

    Mejía, J. M.; Mejía de Gutiérrez, R.; Puertas, F.

    2013-01-01

    This study assesses the viability of using an agro-industrial by-product, rice husk ash (RHA) from a Colombian rice company’s combustion facility, as a total replacement for the commercial sodium silicate ordinarily used in alkaliactivated binders. Fly ash (FA), granulated blast furnace slag (GBFS) and binary 50FA:50GBFS blended pastes were activated with a mix of sodium hydroxide and either sodium silicate or one of two types of RHA. The pastes were characterised for strength, mineralogy and...

  7. Microstructure and Engineering Properties of Alkali Activated Fly Ash -as an environment friendly alternative to Portland cement

    NARCIS (Netherlands)

    Ma, Y.

    2013-01-01

    Alkali activated fly ash (AAFA), also named “geopolymer”, has emerged as a novel engineering material in the construction industry. This material is normally formed by the reaction between fly ash and aqueous hydroxide or alkali silicate solution. With proper mix design, AAFA can present comparable

  8. A Comparative study Of Catalityc Activity Of Heterogeneous Base Of Banana Stem Ash And Fly Ash On Production Of Biodiesel Byultrasonic

    Directory of Open Access Journals (Sweden)

    Marlinda

    2015-08-01

    Full Text Available Abstract The use of heterogeneous catalysts in the production of biodiesel provides many advantages due to heterogeneous catalysts can be easily separated from the product so that it can be reused. This research using heterogeneous catalysts derived from natural materials namely banana stem ash and coal fly ash containing alkali and alkaline earth elements. The preparation of catalyst from banana stem ash and coal fly ash used activator KOH 1.9 N and impregnation with KNO3 15 and then heated to a temperature of 550 0C for 3 hours. Results of preparation banana stem ash contains potassium of 36.52 and surface area of 41.901 m2g. This work presents the effect of ultrasonic assisted of waste cooking oil with methanol as solvent using banana stem ash and coal fly ash as catalyst. The diameter of catalyst particles of banana stem ash and coal fly ash varied at 50 100 150 200 and 250 mesh. The transesterification reaction was performed in the presence of ultrasonic operating frequency constant at 40 kHz methanol molar ratio to oil of 9 1 and reaction time of 30 minutes. The methyl ester biodiesel content of product was 93.26 of banana stems ash and 57 of coal fly ash respectively. The physical property was compared with the National Indonesia Standard SNI 2006 with a density viscosity cloud point flash point and cetane number.

  9. Hydraulic activity of cement mixed with slag from vitrified solid waste incinerator fly ash.

    Science.gov (United States)

    Lin, Kae-Long; Wang, Kuen-Sheng; Tzeng, Bor-Yu; Lin, Chung-Yei

    2003-12-01

    This study investigates the effects of the slag composition on the hydraulic activity in slag blended cement pastes that incorporate synthetic slag prepared by melting CaO-modified municipal solid waste incinerator fly ash. Two types of composition-modified slag were prepared for this study. First, fly ash was mixed with the modifier (CaO) at 5% and 15% (by weight) respectively, resulting in two fly ash mixtures. These mixtures were then melted at 1400 degrees C for 30 minutes and milled to produce two types of slag with different modifier contents, designated as C1-slag and C2-slag. These synthetic slags were blended with ordinary Portland cement at various weight ratios ranging from 10% to 40%. The synthetic slags presented sufficient hydraulic activity, and the heavy metal leaching concentrations all met the EPA's regulatory thresholds. The pore size distribution was determined by mercury intrusion porosimetry, and the results correlated with the compressive strength. The results also indicate that the incorporation of the 10% C1-slag tended to enhance the hydration degree of slag blended cement pastes during the early ages (3-28 days). However, at later ages, no significant difference in hydration degree was observed between ordinary Portland cement pastes and 10% C1-slag blended cement pastes. In the 10% C2-slag case, the trend was similar, but with a more limited enhancement during the early ages (3-28 days). Thus vitrified waste incinerator fly ash is a technically useful additive to cement, reducing the disposal needs for the toxic fly ash. PMID:14986718

  10. Gel nanostructure in alkali-activated binders based on slag and fly ash, and effects of accelerated carbonation

    International Nuclear Information System (INIS)

    Binders formed through alkali-activation of slags and fly ashes, including ‘fly ash geopolymers’, provide appealing properties as binders for low-emissions concrete production. However, the changes in pH and pore solution chemistry induced during accelerated carbonation testing provide unrealistically low predictions of in-service carbonation resistance. The aluminosilicate gel remaining in an alkali-activated slag system after accelerated carbonation is highly polymerised, consistent with a decalcification mechanism, while fly ash-based binders mainly carbonate through precipitation of alkali salts (bicarbonates at elevated CO2 concentrations, or carbonates under natural exposure) from the pore solution, with little change in the binder gel identifiable by nuclear magnetic resonance spectroscopy. In activated fly ash/slag blends, two distinct gels (C–A–S–H and N–A–S–H) are formed; under accelerated carbonation, the N–A–S–H gel behaves comparably to fly ash-based systems, while the C–A–S–H gel is decalcified similarly to alkali-activated slag. This provides new scope for durability optimisation, and for developing appropriate testing methodologies. -- Highlights: •C-A-S-H gel in alkali-activated slag decalcifies during accelerated carbonation. •Alkali-activated fly ash gel changes much less under CO2 exposure. •Blended slag-fly ash binder contains two coexisting gel types. •These two gels respond differently to carbonation. •Understanding of carbonation mechanisms is essential in developing test methods

  11. Alkali-activated fly ash. Relationship between mechanical strength gains and initial ash chemistry

    Directory of Open Access Journals (Sweden)

    Palomo, A.

    2008-09-01

    Full Text Available Alkali-activated fly ash is the primary component of a new generation of high-strength, durable binders with excellent mechanical properties and durability (on occasion bettering traditional Portland cement performance. Moreover, development of these cements may contribute to mitigating CO2 emissions, since the base material is an industrial by-product. The present study was conducted to determine the effect of the composition of the initial materials (SiO2/Al2O3 and Na2O/Al2O3 ratios on the mechanical properties, nature and composition of the reaction products. The results obtained indicate that there is no linear relationship between these ratios and mechanical strength, but rather a series of optimal values above and below which strength declines. In the specific case of the ratios studied in the present paper, these values were: SiO2/Al2O3= 4.0 and Na2O/Al2O3= 1.0 (molar ratios.Las cenizas volantes activadas alcalinamente constituyen la base de una nueva generación de cementos con muy interesantes propiedades mecánicas, adherentes y durables (a veces incluso mejores que las de los cementos Portland tradicionales. Adicionalmente el desarrollo de estos cementos podría contribuir a mitigar las emisiones de CO2 a la atmósfera, ya que el material base de los mismos puede estar formado por subproductos industriales. En la presente investigación se realizó un estudio para determinar la influencia de la composición de los materiales iniciales (ratios SiO2/Al2O3 y Na2O/Al2O3 en las propiedades mecánicas y en la naturaleza y composición de los productos de reacción. Los resultados obtenidos indican que no existe una relación lineal de dichas ratios con las resistencias mecánicas, sino que existen unos valores óptimos, por encima y debajo de los cuales las resistencias mecánicas disminuyen. En el caso concreto de las ratios estudiadas en el presente trabajo estos valores serian: SiO2/Al2O3= 4,0 y Na2O/Al2O3= 1,0 (relaciones molares

  12. Tailoring fly ash activated with bentonite as adsorbent for complex wastewater treatment

    International Nuclear Information System (INIS)

    Highlights: ► The spent adsorbent annealed at 500 °C can be a suggestion for padding in stone blocks. ► The cations can be adsorbent by the silanol group (Si-OH) of the layers from bentonite ► Copper has a higher affinity for the active sites on adsorbent FAw + B than cadmium. ► This substrate can be recommended for simultaneous removal of heavy metals and MB. ► FAw + B is recommended for wastewater treatment resulted in the dyes finishing industry. - Abstract: Used as adsorbent, alkali fly ash represents a low cost solution for advanced wastewater treatment. The alkali treatment raises sustainability issues therefore, in this research we aim to replace alkali fly ash with washed fly ash (FAw). For improving the adsorption capacity of washed fly ash, bentonite powder (B) was added, as a natural adsorbent with a composition almost identical to the fly ash. The new adsorbent was characterized by AFM, XRD, FTIR, SEM, EDS and the surface energy was evaluated by contact angle measurements. For understanding the complex adsorption process on this mixed substrate, preliminary tests were developed on synthetic wastewaters containing a single pollutant system (heavy metal), binary (two-heavy metals) and ternary (dye and two heavy metals) systems. Experiments were done on synthetic wastewaters containing methylene blue, cadmium and copper, using FAw, B and their powder mixtures. The pseudo-second order kinetics could well model all the processes, indicating a good adsorbent material which can be used for the pollutants removal from wastewater. After adsorption the substrates loaded with pollutants, annealed at 500 °C can be reused for padding in stone blocks.

  13. Tailoring fly ash activated with bentonite as adsorbent for complex wastewater treatment

    Energy Technology Data Exchange (ETDEWEB)

    Visa, Maria, E-mail: maria.visa@unitbv.ro [Transilvania University of Brasov, Department Renewable Energy Systems and Recycling, Eroilor 29, 500036 Brasov (Romania)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer The spent adsorbent annealed at 500 Degree-Sign C can be a suggestion for padding in stone blocks. Black-Right-Pointing-Pointer The cations can be adsorbent by the silanol group (Si-OH) of the layers from bentonite Black-Right-Pointing-Pointer Copper has a higher affinity for the active sites on adsorbent FAw + B than cadmium. Black-Right-Pointing-Pointer This substrate can be recommended for simultaneous removal of heavy metals and MB. Black-Right-Pointing-Pointer FAw + B is recommended for wastewater treatment resulted in the dyes finishing industry. - Abstract: Used as adsorbent, alkali fly ash represents a low cost solution for advanced wastewater treatment. The alkali treatment raises sustainability issues therefore, in this research we aim to replace alkali fly ash with washed fly ash (FAw). For improving the adsorption capacity of washed fly ash, bentonite powder (B) was added, as a natural adsorbent with a composition almost identical to the fly ash. The new adsorbent was characterized by AFM, XRD, FTIR, SEM, EDS and the surface energy was evaluated by contact angle measurements. For understanding the complex adsorption process on this mixed substrate, preliminary tests were developed on synthetic wastewaters containing a single pollutant system (heavy metal), binary (two-heavy metals) and ternary (dye and two heavy metals) systems. Experiments were done on synthetic wastewaters containing methylene blue, cadmium and copper, using FAw, B and their powder mixtures. The pseudo-second order kinetics could well model all the processes, indicating a good adsorbent material which can be used for the pollutants removal from wastewater. After adsorption the substrates loaded with pollutants, annealed at 500 Degree-Sign C can be reused for padding in stone blocks.

  14. Activation of Rejected Fly Ash Using Flue Gas Desulphurization (FGD) Sludge

    Institute of Scientific and Technical Information of China (English)

    QIAO Xiu-chen; POON Chisun; LIN Zong-shou

    2003-01-01

    Low-grade fly ash ( rejected fly ash, rFA ), a significant portion of the pulverized fuel ash ( PFA ) produced from coal-fired power plauts and rejected from the ash classifying process, remains unused due to its high carbon content and large particle size ( > 45μm ). But it is thonght that the rejected ash may have potential uses in chemical stabilization/solidification ( S/S ) processes which need relatively lower strengths and a lower chemical reactivity. Flue Gas Desulphurisation ( FGD ) sludge is a by-product of air pollution control equipment in coal fired power plants whose chemical composition is mainly gypsum. As there is no effective usage of both of these two ntaterials , it is of interest to research on the possible octtivation of rFA using FGD . This paper presents experimental results of a study on the properties of rFA activated by the FGD in rFA-cement pastes. Different percetages of FGD were added into the mix to study the effects of the FGD on the reaction of the rFA blended cement pastes.The results show that FGD takes effect as an activator only at late curing ages. Adding Ca ( OH)2 enhances the effect of FGD on activating the hytration of rFA. Also, 10% FGD by weight of rFA is the optimal addition in the rFA-cement pastes. The results of the compressive strength measurements correlate well with the porosity results.

  15. Dielectric properties of fly ash

    Indian Academy of Sciences (India)

    S C Raghavendra; R L Raibagkar; A B Kulkarni

    2002-02-01

    This paper reports the dielectric properties of fly ash. The dielectric measurements were performed as a function of frequency and temperature. The sample of fly ash shows almost similar behaviour in the frequency and temperature range studied. The large value of dielectric constant in the typical frequency range is because of orientation polarization and tight binding force between the ions or atoms in the fly ash. The sample of fly ash is of great scientific and technological interest because of its high value of dielectric constant (104).

  16. Experimental study on workability of alkali activated fly ash and slag-based geopolymer concretes

    NARCIS (Netherlands)

    Arbi, K.A.; Nedeljkovic, M.; Zuo, Y.; Grunewald, S.; Keulen, A.; Ye, G.

    2015-01-01

    This paper presents an investigation on workability and strength of geopolymer concrete made of fly ash (FA), blast furnace slag (BFS) and a multicompound activator of Na2SiO3 and NaOH solutions. The FA/BFS ratios were 100:0, 70:30, 60:40, 50:50, 40:60, 30:70 and 0:100. The workability of geopolymer

  17. The use of alkali-activated fly ash grouts for the remediation of AMD from underground mines

    International Nuclear Information System (INIS)

    In preparation for a field demonstration, laboratory studies were conducted using several fly ash grout formulations to determine the optimum grout for an underground mine environment. This paper discusses the portion of the overall project designed to examine grout-acid mine drainage (AMD) interactions including neutralization, leaching and armoring of the grouts. Leaching tests were performed to study the effects of fly ash grout on AMD, including the effects of armoring. The goal of this project is to study the feasibility of in-situ acid mine drainage treatment by injecting alkali-activated fly ash grout into an underground mine

  18. Alkali-activated fly ash-based geopolymers with zeolite or bentonite as additives

    Energy Technology Data Exchange (ETDEWEB)

    Mingyu Hu; Xiaomin Zhu; Fumei Long [Nanchang University, Nanchang (China). College of Civil Engineering

    2009-11-15

    Geopolymers were synthesized by using fly ash as the main starting material, zeolite or bentonite as supplementary materials, and NaOH and CaO together as activator. An orthogonal array testing protocol was used to analyze the influence of the mix proportion on the properties of the geopolymers. The results indicate that the concentration of NaOH solution and the CaO content play an important role on the strength of the materials. Especially, with zeolite as additive, the fly ash-based geopolymer shows the highest strength and the best sulfate resistance. Infrared spectroscopy, X-ray, and SEM-EDX demonstrate that supplementary zeolite may involve the process of geopolymerization to form a stable zeolitic structure and improve the properties of the geopolymer. Bentonite simply acts as a filler to make the geopolymer more compact, but shows no improvement on the compositions and the microstructures of the geopolymer.

  19. Using fly ash for construction

    Energy Technology Data Exchange (ETDEWEB)

    Valenti, M.

    1995-05-01

    Each year electrical utilities generate 80 million tons of fly ash, primarily from coal combustion. Typically, utilities dispose of fly ash by hauling it to landfills, but that is changing because of the increasing cost of landfilling, as well as environmental regulations. Now, the Electric Power Research Institute (EPRI), in Palo Alto, Calif., its member utilities, and manufacturers of building materials are finding ways of turning this energy byproduct into the building blocks of roads and structures by converting fly ash into construction materials. Some of these materials include concrete and autoclaved cellular concrete (ACC, also known as aerated concrete), flowable fill, and light-weight aggregate. EPRI is also exploring uses for fly ash other than in construction materials. One of the more high-end uses for the material is in metal matrix composites. In this application, fly ash is mixed with softer metals, such as aluminum and magnesium, to strengthen them, while retaining their lighter weight.

  20. Microstructure and Engineering Properties of Alkali Activated Fly Ash -as an environment friendly alternative to Portland cement

    OpenAIRE

    Ma, Y.

    2013-01-01

    Alkali activated fly ash (AAFA), also named “geopolymer”, has emerged as a novel engineering material in the construction industry. This material is normally formed by the reaction between fly ash and aqueous hydroxide or alkali silicate solution. With proper mix design, AAFA can present comparable or superior engineering properties to Portland cement. Moreover, this material shows great potential for sustainable development since its production has a significantly lower CO2 emission than the...

  1. The effect of activating solution on the mechanical strength, reaction rate, mineralogy, and microstructure of alkali-activated fly ash

    NARCIS (Netherlands)

    Ma, Y.; Hu. J.; Ye, G.

    2012-01-01

    Alkali-activated fly ash (AAF) is a promising material that exhibits comparable material properties as cement-based materials but with much less CO2 emission. In the present work, the effect of activating solution (SiO2 and Na2O content) on the performance of AAF was studied by means of isothermal c

  2. Electrodialytic treatment of fly ash

    DEFF Research Database (Denmark)

    Jensen, Pernille Erland; Pedersen, Anne Juul; Kirkelund, Gunvor Marie;

    Heavy metals are removed from the fly ashes by an electrodialytic treatment with the aim of up-grading the ashes for reuse in stead of disposal in landfill.A great potential for upgrading of bio- and waste incineration ashes by electrodialytic treatment exists. In the future, the applicability...

  3. Effect TiO2 of Made of Ash Fly on Crystallization Activation Energy and Index

    OpenAIRE

    Li Feng; Liu Xiangdong

    2015-01-01

    In this work, CAS system glass-ceramics with different components were prepared by a high temperature melting method. The high alumina fly ash and quartz sand were used as the main raw materials in Inner Mongolia where they were very rich and cheap. The nucleation agent was TiO2. According to the thermodynamics calculation, the reaction trend of the new phase transformation was compared. The nucleation and crystal growth rate were analyzed based on the point of dynamics. The activation energy...

  4. Fly ash. Quality recycling material

    Energy Technology Data Exchange (ETDEWEB)

    Blomster, D.; Leisio, C.

    1996-11-01

    Imatran Voima`s coal-fired power plants not only generate power and heat but also produce fly ash which is suitable raw material for recycling. This material for recycling is produced in the flue gas cleaning process. It is economical and, thanks to close quality control, is suitable for use as a raw material in the building materials industry, in asphalt production, and in earthworks. Structures made from fly ash are also safe from an environmental point of view. (orig.)

  5. Material and structural characterization of alkali activated low-calcium brown coal fly ash.

    Science.gov (United States)

    Skvára, Frantisek; Kopecký, Lubomír; Smilauer, Vít; Bittnar, Zdenek

    2009-09-15

    The waste low-calcium Czech brown coal fly ash represents a considerable environmental burden due to the quantities produced and the potentially high content of leachable heavy metals. The heterogeneous microstucture of the geopolymer M(n) [-(Si-O)(z)-Al-O](n).wH(2)O, that forms during the alkaline activation, was examined by means of microcalorimetry, XRD, TGA, DSC, MIP, FTIR, NMR MAS ((29)Si, (27)Al, (23)Na), ESEM, EDS, and EBSD. The leaching of heavy metals and the evolution of compressive strength were also monitored. The analysis of raw fly ash identified a number of different morphologies, unequal distribution of elements, Fe-rich rim, high internal porosity, and minor crystalline phases of mullite and quartz. Microcalorimetry revealed exothermic reactions with dependence on the activator alkalinity. The activation energy of the geopolymerization process was determined as 86.2kJ/mol. The X-ray diffraction analysis revealed no additional crystalline phases associated with geopolymer formation. Over several weeks, the (29)Si NMR spectrum testified a high degree of polymerization and Al penetration into the SiO(4) tetrahedra. The (23)Na NMR MAS spectrum hypothesized that sodium is bound in the form of Na(H(2)O)(n) rather than Na(+), thus causing efflorescence in a moisture-gradient environment. As and Cr(6+) are weakly bonded in the geopolymer matrix, while excellent immobilization of Zn(2+), Cu(2+), Cd(2+), and Cr(3+) are reported.

  6. Pozzolanic activity of clinoptilolite: A comparative study with silica fume, fly ash and a non-zeolitic natural pozzolan

    Energy Technology Data Exchange (ETDEWEB)

    B. Uzal; L. Turanli; H. Yucel; M.C. Goncuoglu; A. Culfaz [Nigde University, Nigde (Turkey). Department of Civil Engineering

    2010-03-15

    Pozzolanic activity of clinoptilolite, the most common natural zeolite mineral, was studied in comparison to silica fume, fly ash and a non-zeolitic natural pozzolan. Chemical, mineralogical and physical characterizations of the materials were considered in comparative evaluations. Pozzolanic activity of the natural zeolite was evaluated with various test methods including electrical conductivity of lime-pozzolan suspensions; and free lime content, compressive strength and pore size distribution of hardened lime-pozzolan pastes. The results showed that the clinoptilolite possessed a high lime-pozzolan reactivity that was comparable to silica fume and was higher than fly ash and a non-zeolitic natural pozzolan. The high reactivity of the clinoptilolite is attributable to its specific surface area and reactive SiO{sub 2} content. Relatively poor strength contribution of clinoptilolite in spite of high pozzolanic activity can be attributable to larger pore size distribution of the hardened zeolite-lime product compared to the lime-fly ash system.

  7. Method for increasing -SiC yield on solid state reaction of coal fly ash and activated carbon powder

    Indian Academy of Sciences (India)

    Sulardjaka; Jamasri; M W Wildan; Kusnanto

    2011-07-01

    A novel process for increasing -SiC yield on solid state reaction of coal fly ash and micro powder activated carbon powder has been proposed. -SiC powder was synthesized at temperature 1300°C for 2 h under vacuum condition with 1 l/min argon flow. Cycling synthesis process has been developed for increasing -SiC yield on solid state reaction of coal fly ash and activated carbon powder. Synthesized products were analyzed by XRD with Cu-K radiation, FTIR spectrometer and SEM fitted with EDAX. The results show that the amount of relative -SiC is increased with the number of cycling synthesis.

  8. Tailoring fly ash activated with bentonite as adsorbent for complex wastewater treatment

    Science.gov (United States)

    Visa, Maria

    2012-12-01

    Used as adsorbent, alkali fly ash represents a low cost solution for advanced wastewater treatment. The alkali treatment raises sustainability issues therefore, in this research we aim to replace alkali fly ash with washed fly ash (FAw). For improving the adsorption capacity of washed fly ash, bentonite powder (B) was added, as a natural adsorbent with a composition almost identical to the fly ash. The new adsorbent was characterized by AFM, XRD, FTIR, SEM, EDS and the surface energy was evaluated by contact angle measurements. For understanding the complex adsorption process on this mixed substrate, preliminary tests were developed on synthetic wastewaters containing a single pollutant system (heavy metal), binary (two-heavy metals) and ternary (dye and two heavy metals) systems. Experiments were done on synthetic wastewaters containing methylene blue, cadmium and copper, using FAw, B and their powder mixtures. The pseudo-second order kinetics could well model all the processes, indicating a good adsorbent material which can be used for the pollutants removal from wastewater. After adsorption the substrates loaded with pollutants, annealed at 500 °C can be reused for padding in stone blocks.

  9. Experimental study on fly ash capture mercury in flue gas

    Institute of Scientific and Technical Information of China (English)

    Mercedes; DíAZ-SOMOANO; Patricia; ABAD-VALLE; M.Rosa; MARTíNEZ-TARAZONA

    2010-01-01

    Systematic experiments were conducted on a fixed-bed reactor to investigate the interaction between fly ash and mercury,the results implied that fly ash can capture mercury effectively.Among different fly ashes,the unburned carbon in the FA2 and FA3 fly ashes has the highest mercury capture capacity,up to 10.3 and 9.36 μg/g,respectively,which is close to that of commercial activated carbon.There is no obvious relationship between mercury content and carbon content or BET surface area of fly ash.Petrography classification standard was applied to distinguish fly ash carbon particles.Carbon content is not the only variable that controls mercury capture on fly ash,there are likely significant differences in the mercury capture capacities of the various carbon forms.Mercury capture capacity mainly depends on the content of anisotropy carbon particles with porous network structure.

  10. Alkali activated fly ash binders. A comparative study between sodium and potassium activators

    Directory of Open Access Journals (Sweden)

    Criado, M.

    2006-03-01

    Full Text Available This paper shows the effect of the nature of some alkaline activators in the microstructural development of thermal-alkali activated f/y ash systems. The alkaline compounds employed in this investigation were: NaOH, KOH, Na2C03, K2C03, sodium silicate and potassium silicate. Results confirm that the main reaction product of the activation process (throughout the studied systems is the amorphous alkaline aluminosilicate gel with a three-dimensional structure already observed in earlier research. It has been proved that the type of anion and cation involved in the activation reaction of the ashes not only affects the microstructural development of the systems but the Si/Al ratio of that prezeolitic gel too. For example, in the presence of soluble silicate ions the content of Si in the final structure is notably increased (Si/Al =2.7-3.0, however carbonate ions play a different role since the formation of Sodium or Potassium carbonate/bicarbonate acidifies the system and consequently the reaction rate is considerably slowed. Finally it is evident that; when all experimental conditions are equal, sodium has a greater capacity than potassium to accelerate the setting and hardening reactions of fly ash and also to stimulate the growth of certain zeolitic crystals (reaction by-products. In general it can be affirmed that OH- ion acts as a reaction catalyst; and the alkaline metal (M+ acts as a structure-forming element.Este trabajo muestra el efecto de la naturaleza del activador alcalino en el desarrollo microestructural de sistemas de ceniza volante, activados térmica y alcalinamente. Los componentes alcalinos empleados en esta investigación fueron: NaOH, KOH, Na2C03, K2C03, silicato sódico y silicato potásico. Los resultados obtenidos confirman que el principal producto de reacción del proceso de activación (a través de los sistemas estudiados es un gel de aluminosilicato alcalino amorfo con estructura tridimensional ya observada en trabajos

  11. Hydraulic activity of belite cement from class C coal fly ash. Effect of curing and admixtures

    Directory of Open Access Journals (Sweden)

    Guerrero, A.

    2006-09-01

    Full Text Available The effect of curing method and a water-reducing additive on the hydraulic activity of high lime content (ASTM type C fly ash belite cement (FABC-2-W is reported. A class C fly ash was subjected to hydrothermal treatment and subsequent calcination to synthesize FABC. Hydraulic activity was evaluated in the cement paste over 180 days from the physically bound water content as determined by thermogravimetric analysis and the degree of hydration, in turn found with X-ray diffraction (XRD analysis. Mechanical strength, porosity and pore size distribution were also studied in equivalent mortar samples.En este trabajo se discute la influencia del tipo de curado y de un aditivo reductor de la demanda de agua en la actividad hidráulica de un cemento belítico de cenizas volantes de alto contenido en cal denominado (CBCV-2-A. Este cemento ha sido sintetizado por una ruta húmeda hidrotermal con posterior calcinación, empleando ceniza volante de alto contenido en cal (ASTM tipo C como materia prima. La actividad hidráulica se ha estudiado en la pasta de cemento, durante un periodo de 180 días, por medio del contenido de agua combinada, determinada por análisis termogravimétrico, y el grado de hidratación por difracción de rayos X (DRX. La resistencia mecánica y la porosidad total y distribución de tamaño de poro se han estudiado en probetas equivalentes de mortero

  12. DURABILITY OF HARDENED FLY ASH PASTE

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The mechanical properties and durability ( mainly frost-resistance and carbonation resistance ) of fly ash-CaO-CaSO4 .2H2O hardened paste are studied. The relationship among durability of harden ed fly ash paste, the quantity and distribution of hydrates and the initial p aste texture of hardened fly ash paste is presented.

  13. High-resolution nanoprobe X-ray fluorescence characterization of heterogeneous calcium and heavy metal distributions in alkali-activated fly ash.

    Science.gov (United States)

    Provis, John L; Rose, Volker; Bernal, Susan A; van Deventer, Jannie S J

    2009-10-01

    The nanoscale distribution of elements within fly ash and the aluminosilicate gel products of its alkaline activation ("fly ash geopolymers") are analyzed by means of synchrotron X-ray fluorescence using a hard X-ray Nanoprobe instrument. The distribution of calcium within a hydroxide-activated (fly ash/KOH solution) geopolymer gel is seen to be highly heterogeneous, with these data providing for the first time direct evidence of the formation of discrete high-calcium particles within the binder structure of a geopolymer synthesized from a low-calcium (geopolymer gel binder structure surrounding the unreacted fly ash particles. This has important implications for the understanding of calcium chemistry within aluminosilicate geopolymer gel phases. Additionally, chromium and iron are seen to be very closely correlated within the structures of both fly ash and the geopolymer product and remain within the regions of the geopolymer which can be identified as unreacted fly ash particles. Given that the potential for chromium release has been one of the queries surrounding the widespread utilization of construction materials derived from fly ash, the observation that this element appears to be localized within the fly ash rather than dispersed throughout the gel binder indicates that it is unlikely to be released problematically into the environment.

  14. Rice husk ash as a source of silica in alkali-activated fly ash and granulated blast furnace slag systems

    Directory of Open Access Journals (Sweden)

    Mejía, J. M.

    2013-09-01

    Full Text Available This study assesses the viability of using an agro-industrial by-product, rice husk ash (RHA from a Colombian rice company’s combustion facility, as a total replacement for the commercial sodium silicate ordinarily used in alkaliactivated binders. Fly ash (FA, granulated blast furnace slag (GBFS and binary 50FA:50GBFS blended pastes were activated with a mix of sodium hydroxide and either sodium silicate or one of two types of RHA. The pastes were characterised for strength, mineralogy and microstructure. The findings showed that the agro-industrial by-product can be used to yield alkali-activated materials with 7-day mechanical strengths on the order of 42 MPa. The study confirmed that both amorphous silica and part of the crystalline silica present in RHA participate in the alkaline activation process, providing the alkalinity is suitably adjusted.Este estudio evalúa la viabilidad de utilizar un subproducto agroindustrial, la ceniza de cascarilla de arroz (RHA proveniente de un equipo combustor de una empresa Arrocera en Colombia, como reemplazo total de la sílice aportada por el silicato de sodio comercial en sistemas cementicios activados alcalinamente. Se prepararon pastas de ceniza volante (FA, de escoria de alto horno (GBFS y un sistema binario 50FA:50GBFS, que fueron activadas por una mezcla de silicato de sodio e hidróxido de sodio, y por dos tipos de RHA. Las mezclas se caracterizaron mecánica, mineralógica y microestructuralmente. Los resultados demuestran que es posible obtener materiales activados alcalinamente con resistencias mecánicas del orden de 42 MPa, a 7 días de curado, utilizando el subproducto agroindustrial. Este estudio corrobora que tanto la sílice amorfa como parte de la sílice cristalina presente en RHA tienen la posibilidad de participar en el proceso de activación alcalina, siempre y cuando las condiciones de alcalinidad estén adecuadamente ajustadas.

  15. Mechanical and microstructural properties of alkali-activated fly ash geopolymers.

    Science.gov (United States)

    Komljenović, M; Bascarević, Z; Bradić, V

    2010-09-15

    This paper investigates the properties of geopolymer obtained by alkali-activation of fly ash (FA), i.e. the influence of characteristics of the representative group of FA (class F) from Serbia, as well as that of the nature and concentration of various activators on mechanical and microstructural properties of geopolymers. Aqueous solutions of Ca(OH)(2), NaOH, NaOH+Na(2)CO(3), KOH and sodium silicate (water glass) of various concentrations were used as alkali activators. It was established that the nature and concentration of the activator was the most dominant parameter in the alkali-activation process. In respect of physical characteristics of FA, the key parameter was fineness. The geopolymer based on FA with the highest content of fine particles (<43 microm), showed the highest compressive strength in all cases. Regardless of FA characteristics, nature and concentration of the activator, the alkali-activation products were mainly amorphous. The formation of crystalline phases (zeolites) occurred in some cases, depending on the reaction conditions. The highest compressive strength was obtained using sodium silicate. Together with the increase of sodium silicate SiO(2)/Na(2)O mass ratio, the atomic Si/Al ratio in the reaction products was also increased. Under the experimental conditions of this investigation, high strength was directly related to the high Si/Al ratio.

  16. Mechanical and microstructural properties of alkali-activated fly ash geopolymers

    Energy Technology Data Exchange (ETDEWEB)

    Komljenovic, M., E-mail: miroslav.komljenovic@imsi.rs [Institute for Multidisciplinary Research, Material Science, Kneza Viseslava 1, 11030 Belgrade (Serbia); Bascarevic, Z., E-mail: zvezdana@cms.bg.ac.rs [Institute for Multidisciplinary Research, Material Science, Kneza Viseslava 1, 11030 Belgrade (Serbia); Bradic, V., E-mail: violeta.bradic@cms.bg.ac.rs [Institute for Multidisciplinary Research, Material Science, Kneza Viseslava 1, 11030 Belgrade (Serbia)

    2010-09-15

    This paper investigates the properties of geopolymer obtained by alkali-activation of fly ash (FA), i.e. the influence of characteristics of the representative group of FA (class F) from Serbia, as well as that of the nature and concentration of various activators on mechanical and microstructural properties of geopolymers. Aqueous solutions of Ca(OH){sub 2}, NaOH, NaOH + Na{sub 2}CO{sub 3}, KOH and sodium silicate (water glass) of various concentrations were used as alkali activators. It was established that the nature and concentration of the activator was the most dominant parameter in the alkali-activation process. In respect of physical characteristics of FA, the key parameter was fineness. The geopolymer based on FA with the highest content of fine particles (<43 {mu}m), showed the highest compressive strength in all cases. Regardless of FA characteristics, nature and concentration of the activator, the alkali-activation products were mainly amorphous. The formation of crystalline phases (zeolites) occurred in some cases, depending on the reaction conditions. The highest compressive strength was obtained using sodium silicate. Together with the increase of sodium silicate SiO{sub 2}/Na{sub 2}O mass ratio, the atomic Si/Al ratio in the reaction products was also increased. Under the experimental conditions of this investigation, high strength was directly related to the high Si/Al ratio.

  17. Impact of activator type on the immobilisation of lead in fly ash-based geopolymer.

    Science.gov (United States)

    Lee, Sujeong; van Riessen, Arie; Chon, Chul-Min; Kang, Nam-Hee; Jou, Hyeong-Tae; Kim, Youn-Joong

    2016-03-15

    Immobilisation of heavy metals in geopolymers has attracted attention as a potential means of treating toxic wastes. Lead is known to be effectively immobilised in a geopolymer matrix, but detailed explanation for the mechanisms involved and the specific chemical form of lead are not fully understood. To reveal the effect of the activator types on the immobilisation of lead in geopolymers, 0.5 and 1.0wt% lead in the form of lead nitrate was mixed with fly ash and alkaline activators. Different alkaline activators (either combined sodium hydroxide and sodium silicate or sodium aluminate) were used to achieve the target Si:Al ratios 2.0 and 5.0 in geopolymers. Zeolite was formed in aluminate-activated geopolymers having a Si:Al ratio of 2.0, but the zeolite crystallization was suppressed as lead content increased. No specific crystalline phase of lead was detected by X-ray diffraction, electron diffraction or FT-IR spectrometry. In fact, double Cs corrected TEM analysis revealed that lead was evenly distributed with no evidence of formation of a specific lead compound. A sequential extraction procedure for fractionation of lead showed that lead did not exist as an exchangeable ion in geopolymers, regardless of activator type used. Aluminate activation is shown to be superior in the immobilisation of lead because about 99% of extracted lead existed in the oxidizing and residual fractions.

  18. Impact of activator type on the immobilisation of lead in fly ash-based geopolymer.

    Science.gov (United States)

    Lee, Sujeong; van Riessen, Arie; Chon, Chul-Min; Kang, Nam-Hee; Jou, Hyeong-Tae; Kim, Youn-Joong

    2016-03-15

    Immobilisation of heavy metals in geopolymers has attracted attention as a potential means of treating toxic wastes. Lead is known to be effectively immobilised in a geopolymer matrix, but detailed explanation for the mechanisms involved and the specific chemical form of lead are not fully understood. To reveal the effect of the activator types on the immobilisation of lead in geopolymers, 0.5 and 1.0wt% lead in the form of lead nitrate was mixed with fly ash and alkaline activators. Different alkaline activators (either combined sodium hydroxide and sodium silicate or sodium aluminate) were used to achieve the target Si:Al ratios 2.0 and 5.0 in geopolymers. Zeolite was formed in aluminate-activated geopolymers having a Si:Al ratio of 2.0, but the zeolite crystallization was suppressed as lead content increased. No specific crystalline phase of lead was detected by X-ray diffraction, electron diffraction or FT-IR spectrometry. In fact, double Cs corrected TEM analysis revealed that lead was evenly distributed with no evidence of formation of a specific lead compound. A sequential extraction procedure for fractionation of lead showed that lead did not exist as an exchangeable ion in geopolymers, regardless of activator type used. Aluminate activation is shown to be superior in the immobilisation of lead because about 99% of extracted lead existed in the oxidizing and residual fractions. PMID:26642447

  19. The effect of activating solution on the mechanical strength, reaction rate, mineralogy, and microstructure of alkali-activated fly ash

    OpenAIRE

    Ma, Y.; Hu J.; Ye, G.

    2012-01-01

    Alkali-activated fly ash (AAF) is a promising material that exhibits comparable material properties as cement-based materials but with much less CO2 emission. In the present work, the effect of activating solution (SiO2 and Na2O content) on the performance of AAF was studied by means of isothermal calorimetry and X-ray diffraction analysis. Meanwhile, the pore structure of AAF was examined by mercury intrusion porosimetry combined with environmental scanning electron microscope. The results i...

  20. Alkali activated fly ash binders. A comparative study between sodium and potassium activators

    OpenAIRE

    Criado, M.; Palomo, A.; Fernández-Jiménez, A.

    2006-01-01

    This paper shows the effect of the nature of some alkaline activators in the microstructural development of thermal-alkali activated f/y ash systems. The alkaline compounds employed in this investigation were: NaOH, KOH, Na2C03, K2C03, sodium silicate and potassium silicate. Results confirm that the main reaction product of the activation process (throughout the studied systems) is the amorphous alkaline aluminosilicate gel with a three-dimensional structure already observed in earlier resea...

  1. Effect TiO2 of Made of Ash Fly on Crystallization Activation Energy and Index

    Directory of Open Access Journals (Sweden)

    Li Feng

    2015-01-01

    Full Text Available In this work, CAS system glass-ceramics with different components were prepared by a high temperature melting method. The high alumina fly ash and quartz sand were used as the main raw materials in Inner Mongolia where they were very rich and cheap. The nucleation agent was TiO2. According to the thermodynamics calculation, the reaction trend of the new phase transformation was compared. The nucleation and crystal growth rate were analyzed based on the point of dynamics. The activation energy and crystallization index were calculated by making use of an equation. With increasing the content of TiO2, the activation energy and index of crystallization of glass ceramics firstly increased to the maximum 1.95, then deceased. The content of TiO2 had an optimal value of about 8%. Under this condition, the activation energy of crystallization reached to the minimum 225.87 KJ/mol. and the crystals precipitated more easily.

  2. Layer-by-Layer Assembly and Photocatalytic Activity of Titania Nanosheets on Coal Fly Ash Microspheres

    Directory of Open Access Journals (Sweden)

    Xing Cui

    2014-01-01

    Full Text Available In order to address the problem with titania distribution and recovery, series of Ti0.91O2/CFA photocatalysts (Ti0.91O2/CFA-n, n=2,4,6, and 8 were fabricated by assembling Ti0.91O2 nanosheets on coal fly ash (CFA microspheres via the layer-by-layer assembly (LBLA process and characterized by scanning electron microscopy (SEM, X-ray diffraction analysis (XRD, N2-sorption, and ultraviolet-visible absorption (UV-vis techniques. The SEM images and UV-vis spectra illustrated that Ti0.91O2 nanosheets were immobilized successfully on the CFA by the LBLA approach and changed the characteristics of CFA noticeably. The photocatalytic activity of Ti0.91O2/CFA was evaluated by the photodegradation of methylene blue (MB under UV irradiation. The results demonstrated that Ti0.91O2/CFA-6 showed the best photocatalytic activity among the series of Ti0.91O2/CFA irradiated for 60 min, with a decoloration rate above 43%. After photocatalysis, the Ti0.91O2/CFA could be easily separated and recycled from aqueous solution and Ti0.91O2 nanosheets were still anchored on the CFA.

  3. Biofuel Combustion Fly Ash Influence on the Properties of Concrete

    Directory of Open Access Journals (Sweden)

    Aurelijus Daugėla

    2016-02-01

    Full Text Available Cement as the binding agent in the production of concrete can be replaced with active mineral admixtures. Biofuel combustion fly ash is one of such admixtures. Materials used for the study: Portland cement CEM I 42.5 R, sand of 0/4 fraction, gravel of 4/16 fraction, biofuel fly ash, superplasticizer, water. Six compositions of concrete were designed by replacing 0%, 5%, 10%, 15% 20%, and 25% of cement with biofuel fly ash. The article analyses the effect of biofuel fly ash content on the properties of concrete. The tests revealed that the increase of biofuel fly ash content up to 20% increases concrete density and compressive strength after 7 and 28 days of curing and decreases water absorption, with corrected water content by using plasticizing admixture. It was found that concrete where 20% of cement is replaced by biofuel ash has higher frost resistance.

  4. Heavy metal removal from MSWI fly ash by electrokinetic remediation coupled with a permeable activated charcoal reactive barrier

    OpenAIRE

    Tao Huang; Dongwei Li; Liu Kexiang; Yuewei Zhang

    2015-01-01

    This paper presents the investigations into the feasibility of the application of a remediation system that couples electrokinetic remediation (EKR) with the permeable reactive barrier (PRB) concept for municipal solid waste incineration (MSWI) fly ash with activated charcoal as the PRB material. The experimental results of this study showed that the proposed combined method can effectively improve the remediation efficiency and that the addition of the oxalic acid to the PRB media before the...

  5. A Research on Particle Constitution of Fly Ash and Pozzolanic Activity of Fly Ash Ground Traditionally%粉煤灰的颗粒组成与磨细灰的火山灰活性

    Institute of Scientific and Technical Information of China (English)

    阮燕; 吴定燕; 高琼英

    2001-01-01

    将通过筛分得到的不同粒径范围的分选灰分别用普通球磨机磨细,探讨普通磨细方式对不同颗粒组成的粉煤灰的影响规律及其提高粉煤灰品质的机理。结果表明:普通粉磨主要是对粉煤灰的粗大颗粒有重要作用,而对粉煤灰中的细颗粒作用不明显。%The particles of fly ash are separated by sieve method.The fly ash of different size distribution is ground by traditional mill.The effect rule of traditional grinding method on different particles of fly ash and the mechanism of improvement on quality of fly ash are discussed.The results show that traditional grinding affects on crassitude particles actively but not fine particles.

  6. ACAA fly ash basics: quick reference card

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    Fly ash is a fine powdery material created when coal is burned to generate electricity. Before escaping into the environment via the utility stacks, the ash is collected and may be stored for beneficial uses or disposed of, if necessary. The use of fly ash provides environmental benefits, such as the conservation of natural resources, the reduction of greenhouse gas emissions and eliminating the needed for ash disposal in landfills. It is also a valuable mineral resource that is used in construction and manufacturing. Fly ash is used in the production of Portland cement, concrete, mortars and stuccos, manufactured aggregates along with various agricultural applications. As mineral filler, fly ash can be used for paints, shingles, carpet backing, plastics, metal castings and other purposes. This quick reference card is intended to provide the reader basic source, identification and composition, information specifically related to fly ash.

  7. Effect of fly ash on autogenous shrinkage

    Energy Technology Data Exchange (ETDEWEB)

    Pipat Termkhajornkit; Toyoharu Nawa; Masashi Nakai; Toshiki Saito [Hokkaido University, Hokkaido (Japan). Division of Structural and Geotechnical Engineering, Graduate School of Engineering

    2005-03-01

    The correlation between autogenous shrinkage and degree of hydration of fly ash was determined with the selective dissolution method. Then, the relationship between the degree of hydration of fly ash and autogenous shrinkage was examined. The results showed that the degree of hydration of fly ash increased as its Blaine surface area increased. The degree of hydration of fly ash increased with time, and autogenous shrinkage increased corresponding to the increase in the degree of hydration of fly ash. Moreover, it was found that the total quantity of Al{sub 2}O{sub 3} in cement-fly ash samples affected autogenous shrinkage at early ages, but the long-term influence was very small.

  8. Settling characteristics of some Indian fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Jain, M.K.; Sastry, B.S. [Indian Institute of Technology, Kharapur (India). Dept. of Mining Engineering

    2003-07-01

    The paper examines the aspects of the solid liquid separation (settling characteristics) of some of the fly ash obtained from coal-fired power plants in India. The application of a coagulating or flocculating agent (polymer) to improve the two properties as indicated is a typical industrial practice. The sources for this study comprise of fly ash, pond ash, and bottom ash and the settling characteristics are studied in conjunction with the flocculating agent polyacrylamide. 4 refs., 4 figs., 3 tabs.

  9. N, S co-doped-TiO2/fly ash beads composite material and visible light photocatalytic activity

    Science.gov (United States)

    Lv, Jun; Sheng, Tong; Su, Lili; Xu, Guangqing; Wang, Dongmei; Zheng, Zhixiang; Wu, Yucheng

    2013-11-01

    Using TiCl4 as the titanium source, urea as the precipitating agent, nano-TiO2/fly ash beads composite materials were prepared by hydrolysis-precipitation method. Using (NH2)2CO and (NH2)2SC as the N and S source respectively, N and S co-doped TiO2/fly ash beads composite materials were prepared by grinding them together according to a certain proportion and calcined at 500 °C for 2 h. The composite materials were characterized by SEM, EDS, XPS, and UV-vis spectrophotometer methods. The UV-vis absorption spectra results show that the absorption edge of un-doped composites is 390 nm while that of doped composites red-shifts to 500 nm. The photocatalytic activity of composite materials was evaluated by degradation of methyl orange under visible light irradiation (halogen lamp, 250 W). The results showed that after irradiation for 1 h, degradation rate of N, S co-doped-TiO2/fly ash beads composite material can reach 65%, while the degradation rate of un-doped sample and P25 were just 10% and 6%, respectively. The composite material also showed excellent recycling properties.

  10. Scale-Up and Demonstration of Fly Ash Ozonation Technology

    Energy Technology Data Exchange (ETDEWEB)

    Rui Afonso; R. Hurt; I. Kulaots

    2006-03-01

    The disposal of fly ash from the combustion of coal has become increasingly important. When the fly ash does not meet the required specification for the product or market intended, it is necessary to beneficiate it to achieve the desired quality. This project, conducted at PPL's Montour SES, is the first near full-scale ({approx}10 ton/day), demonstration of ash ozonation technology. Bituminous and sub bituminous ashes, including two ash samples that contained activated carbon, were treated during the project. Results from the tests were very promising. The ashes were successfully treated with ozone, yielding concrete-suitable ash quality. Preliminary process cost estimates indicate that capital and operating costs to treat unburned carbon are competitive with other commercial ash beneficiation technologies at a fraction of the cost of lost sales and/or ash disposal costs. This is the final technical report under DOE Cooperative Agreement No.: DE-FC26-03NT41730.

  11. Washing of granulated solidification fly ash containing radioactive contaminants

    International Nuclear Information System (INIS)

    Incineration fly ash produced from city garbage, water-and-sewage sludge, and wastes generated by radioactive decontamination activities tends to have a high concentration of radioactive materials, and radioactive cesium in fly ash has high solubility in water. In order to advance the safe processing of incineration fly ash, it is necessary to have a technology for reducing the cesium in the fly ash. Washing the fly ash with water is an effective way of reducing the amount of radioactive cesium. Then, this study developed a new method for washing fly ash after granulated solidification. Laboratory tests showed that 70% or more of the radioactive cesium was removed by washing of the granulated solidification fly ash adjusted into 1-9.5 mm diameter particles under the following conditions: flow rate (SV) ≦ 10h-1 and flow volume ≧ 10 times of fly ash volume. Demonstration tests also confirmed the effectiveness of washing and the reduction of the volume of radioactive wastes. (author)

  12. Fundamental study of low-NOx combustion fly ash utilization

    International Nuclear Information System (INIS)

    This study is principally concerned with characterizing the organic part of coal combustion fly ashes. High carbon fly ashes are becoming more common as by-products of low-NOx combustion technology, and there is need to learn more about this fraction of the fly ash. The project team consists of two universities, Brown and Princeton, and an electrical utility, New England Power. A sample suite of over fifty fly ashes has been gathered from utilities across the United States, and includes ashes from a coals ranging in rank from bituminous to lignite. The characterizations of these ashes include standard tests (LOI, Foam Index), as well as more detailed characterizations of their surface areas, porosity, extractability and adsorption behavior. The ultimate goal is, by better characterizing the material, to enable broadening the range of applications for coal fly ash re-use beyond the current main market as a pozzolanic agent for concretes. The potential for high carbon-content fly ashes to substitute for activated carbons is receiving particular attention. The work performed to date has already revealed how very different the surfaces of different ashes produced by the same utility can be, with respect to polarity of the residual carbon. This can help explain the large variations in acceptability of these ashes as concrete additives

  13. Improved mechanical properties of concretes by fly ash grading

    Energy Technology Data Exchange (ETDEWEB)

    Shu, L.; Lu, Z.; Yan, Y.; Qiao, H.; An, J. [Southeast University of Science and Technology, Mianyang (China)

    2008-08-15

    The influence of the dosage of class II fly ash of different fineness on the mechanical properties of concrete was researched. The result shows that activity in the early phase elevated as the amount of submicron particles increased by grinding the fly ash. Over-grinding resulted in slump decreasing sharply. SEM analysis shows that hydrated products of glass micron-beads in class II fly ash were not found. The synergistic effect between fly ash of different fineness was researched by the Andersen equation. The micro-aggregate effect is the most important factor affecting the strength of concrete. A fourth-order mixture with a 50% replacement of cement by fly ash was studied under conditions of practical production and application. A regression equation which uses slump and compressive strength at 28 d as a function was deduced.

  14. Superplasticizer Addition to Carbon Fly Ash Geopolymers Activated at Room Temperature

    Directory of Open Access Journals (Sweden)

    Lorenza Carabba

    2016-07-01

    Full Text Available Present concerns about global warming due to the greenhouse emissions in the atmosphere have pushed the cement industry to research alternatives to ordinary Portland cement (OPC. Geopolymer binder may constitute a possible breakthrough in the development of sustainable materials: understanding the effectiveness and the influences of superplasticizers on geopolymer systems is one of the essential requirements for its large-scale implementation. This study aims to investigate the possibility of using commercially available chemical admixtures designed for OPC concrete, to improve fresh properties of fly ash-based geopolymers and mortars. A special emphasis is laid upon evaluating their influence on mechanical and microstructural characteristics of the hardened material realized under room-temperature curing conditions. Results indicate that the addition of a polycarboxylic ether-based superplasticizer, in the amount of 1.0 wt. % by mass of fly ash, promotes an improvement in workability without compromising the final strength of the hardened material. Moreover, the addition of the polycarboxylic ether- and acrylic-based superplasticizers induces a refinement in the pore structure of hardened mortar leading to a longer water saturation time.

  15. Electrodialytic removal of heavy metals from fly ashes

    DEFF Research Database (Denmark)

    Pedersen, Anne Juul

    2002-01-01

    The aim of the Ph.D. work was to develop the electrodialytic remediation method for removal of heavy metals from fly ashes. The work was focused on two types of fly ashes: fly ashes from wood combustion and fly ashes from municipal solid waste incineration.......The aim of the Ph.D. work was to develop the electrodialytic remediation method for removal of heavy metals from fly ashes. The work was focused on two types of fly ashes: fly ashes from wood combustion and fly ashes from municipal solid waste incineration....

  16. Construction procedures using self hardening fly ash

    Science.gov (United States)

    Thornton, S. I.; Parker, D. G.

    1980-07-01

    Fly ash produced in Arkansas from burning Wyoming low sulfur coal is self-hardening and can be effective as a soil stabilizing agent for clays and sands. The strength of soil-self hardening fly ash develops rapidly when compacted immediately after mixing. Seven day unconfined compressive strengths up to 1800 psi were obtained from 20% fly ash and 80% sand mixtures. A time delay between mixing the fly ash with the soil and compaction of the mixture reduced the strength. With two hours delay, over a third of the strength was lost and with four hours delay, the loss was over half. Gypsum and some commercial concrete retarders were effective in reducing the detrimental effect of delayed compaction. Adequate mixing of the soil and fly ash and rapid compaction of the mixtures were found to be important parameters in field construction of stabilized bases.

  17. CO{sub 2} capture using fly ash-derived activated carbons impregnated with low molecular mass amines

    Energy Technology Data Exchange (ETDEWEB)

    Smith, K.M.; Arenillas, A.; Drage, T.C.; Snape, C.E. [University of Nottingham, Nottingham (United Kingdom). Nottingham Fuel and Energy Centre

    2005-07-01

    Two different approaches to develop high capacity CO{sub 2} sorbents are presented. Firstly, the modification of the surface chemistry of low cost carbons by impregnation with a basic nitrogen-containing polymer (i.e.polyethylenimine) is described. Relatively low molecular mass (MM) amines, namely diethanolamine (DEA, MM 105) and tetraethylenepentaamineacrylonitrile (TEPAN, MM 311) are used to produce high capacity CO{sub 2} sorbents from activated carbons derived from unburned carbon in fly ash, which have low mesoporosities. The CO{sub 2} adsorption capacity and thermal stability of the prepared sorbents was measured as a function of temperature in a thermogravimetric analyser. The results indicate that TEPAN is more effective than DEA; at a temperature of 75{sup o}C, fly ash-derived activated carbons loaded with TEPAN achieved CO{sub 2} adsorption capacities in excess of 5 wt%, which compares fabvourably with the CO{sub 2} absorption capacity of 6.5 wt% achieved with a mesoporous silica loaded with TEPAN, and outperforms fly ash-derived activated carbons loaded with PEI. TEPAN has also been shown to have a higher thermal stability than DEA. The second approach involves the development of high nitrogen content carbon matrix adsorbents by carbonisation and subsequent thermal or chemical activation of a range of materials (polyacrylonitrile, glucose-amine mixtures, melamine and urea/melamine-formaldehyde resins). The results show that although the amount of nitrogen incorporated to the final adsorbent is important, the N-functionality seems to be more relevant for increasing CO{sub 2} uptake. However, the adsorbent obtained from carbazole-sugar co-pyrolysis, despite the lower amount of N incorporated, shows high CO{sub 2} uptake, up to 9 wt%, probably because the presence of more basic functionalities as determined by XPS analysis. 9 refs., 2 figs.

  18. Selective catalytic reduction of NO by ammonia over oil shale ash and fly ash catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Changtao Yue; Shuyuan Li [University of Petroleum, Beijing (China). State Key Lab of Heavy Oil Processing

    2003-07-01

    Acid rain and urban air pollution, produced mainly by pollutants such as SOX and NOX and other volatile organic compounds, has become the most serious environmental problem. The selective catalytic reduction (SCR) of NO with NH{sub 3} in the presence of oxygen is a wellproven method to limit the NOX emissions. The work in this field has been the subject of much research in recent years. In this paper, NO reduction with NH{sub 3} over oil shale ash or fly ash catalysts was studied. Fe, Cu, V or Ni as active elements was loaded by adding aqueous solutions of the metal nitrate over the oil shale ash or fly ash support. The activities of the catalysts for NO removal were measured in a fixed-bed reactor. According to the results, oil shale ash or fly ash, after pre-treatment, can be reasonably used as the SCR catalyst support to remove NO from flue gas. Cu gave the highest catalytic activity and NO conversion for fly ash while V for oil shale ash. As the support, fly ash is more feasible than oil shale ash. Because of their low cost and high efficiency, the catalysts should be used in the SCR process. Further research on this subject is necessary in the future to understand more details of the SCR system and issue of pollution control. 9 refs., 2 figs., 2 tabs.

  19. Kohonen's feature maps for fly ash categorization.

    Science.gov (United States)

    Nataraja, M C; Jayaram, M A; Ravikumar, C N

    2006-12-01

    Fly ash is a common admixture used in concrete and may constitute up to 50% by weight of the total binder material. Incorporation of fly ash in Portland-cement concrete is highly desirable due to technological, economic, and environmental benefits. This article demonstrates the use of artificial intelligence neural networks for the classification of fly ashes in to different groups. Kohonen's Self Organizing Feature Maps is used for the purpose. As chemical composition of fly ash is crucial in the performance of concrete, eight chemical attributes of fly ashes have been considered. The application of simple Kohonen's one-dimensional feature maps permitted to differentiate three main groups of fly ashes. Three one-dimensional feature maps of topology 8-16, 8-24 and 8-32 were explored. The overall classification result of 8-16 topology was found to be significant and encouraging. The data pertaining to 80 fly ash samples were collected from standard published works. The categorization was found to be excellent and compares well with Canadian Standard Association's [CSA A 3000] classification scheme. PMID:17285691

  20. Effect of Fly Ash on the Electrical Conductivity of Concretes

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The fly ash occasionally has high content of iron oxide and carbon that are good electrical conducting components. This paper investigates the effect of the fly ash used as mineral admixtures on the electrical conductivity of concretes. The electrical properties of concretes using 3 kinds of fly ash with different iron oxide contents have been studied. Experimental results show that at the same fly ash dosage the resistivity of concrete using fly ash with high content of iron oxide is slightly lower than that with low content of iron oxide. However, the concrete resistivity after 14d increases as fly ash dosage increases regardless of iron oxide content in fly ash.

  1. Influence of Bed Ash and Fly Ash Replacement in Mortars

    Directory of Open Access Journals (Sweden)

    S. L. Summoogum-Utchanah

    2015-03-01

    Full Text Available The study evaluates the influence of fly ash and bottom ash as partial cement substitutes in mortars by studying the particle size distribution, consistency, flow, fresh density, air content, compressive strength and flexural strength characteristics. The results revealed that fly ash and cement had relatively the same particle size distribution unlike bottom ash. In the fresh state, as the amount of pozzolans increased in the mixtures, the mortars showed an enhancement in workability, were susceptible to water loss by bleeding, and exhibited a decline in fresh density. The early strength gains of the fly ash samples were low but reached higher than the control after 28 days of curing. The flexural strength increased as the fly ash content rose to reach a maximum at 20 % replacement. However, the 2-day compressive strength of bottom ash samples was higher than the control but decreased after 28 days of curing while the flexural strength declined with addition of bottom ash except at 5 % substitution.

  2. Heavy metals in MSW incineration fly ashes

    DEFF Research Database (Denmark)

    Ferreira, Celia; Ribeiro, Alexandra B.; Ottosen, Lisbeth M.

    2003-01-01

    related to the combustion of MSW and the formation of fly ash, especially in what concerns heavy metals. Treatment of the flue gas in air pollution control equipment plays an important role and the basic processes to accomplish this are explained. Fly ash from a semi-dry flue gas treatment system......Incineration is a common solution for dealing with the increasing amount of municipal solid waste (MSW). During the process, the heavy metals initially present in the waste go through several transformations, ending up in combustion products, such as fly ash. This article deals with some issues...... is characterized regarding its physical-chemical properties: pH, solubility, chemical composition, and leaching, amongst others. Results indicate a high alkalinity and the presence of large amounts of calcium, chlorides, sulfates, carbonates, sodium and potassium. Metal concentrations in fly ash are: 6,2 g...

  3. Composites based on fly ash and clay

    OpenAIRE

    Fidancevska, Emilija; Jovanov, Vojo; Angusheva, Biljana; Srebrenkoska, Vineta

    2014-01-01

    Fly ash is a waste generated from the coal combustion during the production of electricity in the thermal power plants. It presents industrial by-product containing Technologically Enhanced Natural Occurring Radioactive Materials (TENORM) with the great potential for valorisation (1). Fly ash is successfully utilized in cement and concrete industry (2), also in ceramics industry (3) as component for manufacturing bricks and tiles, and recently there are many investigations for production of g...

  4. Biologic effects of oil fly ash.

    OpenAIRE

    Ghio, Andrew J.; Silbajoris, Robert; Carson, Johnny L.; Samet, James M.

    2002-01-01

    Epidemiologic studies have demonstrated increased human morbidity and mortality with elevations in the concentration of ambient air particulate matter (PM). Fugitive fly ash from the combustion of oil and residual fuel oil significantly contributes to the ambient air particle burden. Residual oil fly ash (ROFA) is remarkable in the capacity to provoke injury in experimental systems. The unique composition of this emission source particle makes it particularly useful as a surrogate for ambient...

  5. Suppressing Heavy Metal Leaching through Ball Milling of Fly Ash

    Directory of Open Access Journals (Sweden)

    Zhiliang Chen

    2016-07-01

    Full Text Available Ball milling is investigated as a method of reducing the leaching concentration (often termed stablilization of heavy metals in municipal solid waste incineration (MSWI fly ash. Three heavy metals (Cu, Cr, Pb loose much of their solubility in leachate by treating fly ash in a planetary ball mill, in which collisions between balls and fly ash drive various physical processes, as well as chemical reactions. The efficiency of stabilization is evaluated by analysing heavy metals in the leachable fraction from treated fly ash. Ball milling reduces the leaching concentration of Cu, Cr, and Pb, and water washing effectively promotes stabilization efficiency by removing soluble salts. Size distribution and morphology of particles were analysed by laser particle diameter analysis and scanning electron microscopy. X-ray diffraction analysis reveals significant reduction of the crystallinity of fly ash by milling. Fly ash particles can be activated through this ball milling, leading to a significant decrease in particle size, a rise in its BET-surface, and turning basic crystals therein into amorphous structures. The dissolution rate of acid buffering materials present in activated particles is enhanced, resulting in a rising pH value of the leachate, reducing the leaching out of some heavy metals.

  6. Measurement of natural activity in peat ashes

    International Nuclear Information System (INIS)

    High proportions of radioactive materials in peat ashes may involve radiation hazards during handling and deposition of these waste materials. Measurements have been performed to determine the content of radioactive materials in ashes from peat burning. The activities in fly ash and ''solid'' ash in seven peat-fired power plants in Sweden are presented. The methods of analysing and measuring peat ashes for activity from different radionuclides are described. The activity levels in ash samples are given

  7. Leachability of trace metal elements from fly ashes, and from concrete incorporating fly ashes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, M.H. [National University of Singapore (Singapore); Blanchette, M.C. [Natural Resources Canada, Ottawa, ON (Canada). CANMET Energy Technology Centre; Malhotra, V.M. [Natural Resources Canada, Ottawa, ON (Canada)

    2001-07-01

    Manufacturing portland cement is not environmentally desirable because for every tonne of cement produced, about one tonne of carbon dioxide is released into the atmosphere. This problem can be solved by replacing a portion of portland cement with fly ash, a mineral by-product of burning coal at power generation facilities. A study was conducted to examine the leachability of trace metal elements from a variety of fly ashes from various sources in Canada and the United States along with the concrete incorporating the fly ash. Gold, arsenic, boron, barium cadmium, chromium, copper, mercury, lead and selenium are the regulated elements in leachates. In this study, each of these elements were tested from 9 fly ashes within the limits of the U.S. Environmental Protection Agency and the Canadian regulations for the Transportation of Dangerous Goods. It was shown that in general, but with some exceptions, the leaching of arsenic, boron, nickel and selenium increased with an increase in their content in the fly ash. Arsenic concentration from fly ash obtained from bituminous coal was found to be much higher than that from lignite or from sub-bituminous coal. However, the study also showed that none of the trace metals in the leachates from the fly ash concrete samples exceeded the regulated concentration limits, regardless of the type and percentage of fly ash used. It was concluded that concrete which incorporates fly ash is environmentally stable. It was also concluded that waste product utilization, in terms of using fly ash from power generating facilities, can significantly reduce carbon dioxide emissions when manufacturing portland cement. Typical replacement levels of fly ash in portland cement concrete is about 20 per cent by mass of the total cementitious materials. 10 refs., 14 tabs., 4 figs.

  8. Effect of Activator and Curing Mode on Fly Ash-based Geopolymers

    Institute of Scientific and Technical Information of China (English)

    HOU Yunfen; WANG Dongmin; ZHOU Wenjuan; LU Hongbo; WANG Lin

    2009-01-01

    The influences of concentration and modulus of sodium silicate solution and curing mode on the phase composition,microstructure and strength development in the geopolymers prepared using Class F fly ash were investigated.X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR)and MAS NMR were utilized.Results show that the compressive strength increases as sodium silicate solution modulus increases,but when modulus exceeds 1.4,the compressive strength decreases,and it decreases markedly while the modulus is greater than 2.0.The compressive strength was improved by the increase of sodium silicate solution concentration.When the concentration is 32%, the compressive strength reaches the maximum,then it reduces as concentration increasing.Elevated temperature can increase the strength of samples that synthesized from sodium silicate solution with 32%concentration and modulus 1.2.Compared to the strength of the sample cured at 50℃,the strength of the samples cured at 65 ℃and 80℃are higher at 1 d and 3 d,but the same at 7 d.At high temperature,prolonged curing time will decrease the strength.Long precuring at room temperature before application of heat is beneficial for strength development,and there is about 50%increase in strength of the samples cured at 1 d precuring and 2 d elevated temperature as compared to the strengths of the samples cured for 3 d at elevated temperatures or cured for 28 d at room temperature.The main product of reaction in the geopolymeric material is amorphous alkali aluminosilicate gel.

  9. Sorbents for CO2 capture from high carbon fly ashes.

    Science.gov (United States)

    Maroto-Valer, M Mercedes; Lu, Zhe; Zhang, Yinzhi; Tang, Zhong

    2008-11-01

    Fly ashes with high-unburned-carbon content, referred to as fly ash carbons, are an increasing problem for the utility industry, since they cannot be marketed as a cement extender and, therefore, have to be disposed. Previous work has explored the potential development of amine-enriched fly ash carbons for CO2 capture. However, their performance was lower than that of commercially available sorbents, probably because the samples investigated were not activated prior to impregnation and, therefore, had a very low surface area. Accordingly, the work described here focuses on the development of activated fly ash derived sorbents for CO2 capture. The samples were steam activated at 850 degrees C, resulting in a significant increase of the surface area (1075 m2/g). The activated samples were impregnated with different amine compounds, and the resultant samples were tested for CO2 capture at different temperatures. The CO2 adsorption of the parent and activated samples is typical of a physical adsorption process. The impregnation process results in a decrease of the surface areas, indicating a blocking of the porosity. The highest adsorption capacity at 30 and 70 degrees C for the amine impregnated activated carbons was probably due to a combination of physical adsorption inherent from the parent sample and chemical adsorption of the loaded amine groups. The CO2 adsorption capacities for the activated amine impregnated samples are higher than those previously published for fly ash carbons without activation (68.6 vs. 45 mg CO2/g sorbent).

  10. The Effect of Variation of Molarity of Alkali Activator and Fine Aggregate Content on the Compressive Strength of the Fly Ash: Palm Oil Fuel Ash Based Geopolymer Mortar

    Directory of Open Access Journals (Sweden)

    Iftekhair Ibnul Bashar

    2014-01-01

    Full Text Available The effect of molarity of alkali activator, manufactured sand (M-sand, and quarry dust (QD on the compressive strength of palm oil fuel ash (POFA and fly ash (FA based geopolymer mortar was investigated and reported. The variable investigated includes the quantities of replacement levels of M-sand, QD, and conventional mining sand (N-sand in two concentrated alkaline solutions; the contents of alkaline solution, water, POFA/FA ratio, and curing condition remained constant. The results show that an average of 76% of the 28-day compressive strength was found at the age of 3 days. The rate of strength development from 3 to 7 days was found between 12 and 16% and it was found much less beyond this period. The addition of 100% M-sand and QD shows insignificant strength reduction compared to mixtures with 100% N-sand. The particle angularity and texture of fine aggregates played a significant role in the strength development due to the filling and packing ability. The rough texture and surface of QD enables stronger bond between the paste and the fine aggregate. The concentration of alkaline solution increased the reaction rate and thus enhanced the development of early age strength. The use of M-sand and QD in the development of geopolymer concrete is recommended as the strength variation between these waste materials and conventional sand is not high.

  11. Multitechnique multielemental analysis of coal and fly ash

    International Nuclear Information System (INIS)

    The coal sample is first ashed with high temperature ashing or with RF plasma low temperature ashing. The coal ash or fly ash can be analyzed for major ash elements by fusing with lithium tetraborate in an automatic fusion device, the Claisse Fluxer. The ash samples are also dissolved in a Parr bomb in a mixture of aqua regia and HF. Subsequently, the solutions are analyzed for eight major (Al, Ca, Fe, K, Mg, Na, Si, and Ti) and 20 trace elements (As, B, Ba, Be, Cd, Co, Cr, Cu, Li, Mn, Mo, Ni, P, Pb, Sb, Se, Sr, U, V, and Zn) by inductively coupled plasma emission spectroscopy. Mercury in coal and fly ash is determined on a separate aliquot by the cold vapor atomic absorption technique. Fluorine and chlorine in the samples are determined by fusing with Na2CO3 and Eschka mixture, respectively, and then measuring the two ions in solution with specific ion electrodes. Oxygen in the samples can be determined rapidly and nondestructively by 14-MeV neutron activation analysis. These methods have been tested by analyzing several NBS coal and fly ash standards with good accuracy and reproducibility. 10 tables

  12. Instrumental photon activation analysis of coal fly ashes using the internal standard method coupled with the standard addition method

    International Nuclear Information System (INIS)

    Multielement determinations of coal fly ashes (NIST SRM-1633a and BCR CRM-38) have been carried out by instrumental photon activation analysis using 30 MeV bremsstrahlung and the internal standard method coupled with the standard addition method. In these determinations, some major and minor constituent elements in the samples were properly used as effective internal standards. As a result, it was demonstrated that concentrations of 18 elements were determined accurately and precisely. Furthermore, a similar multielement determination has also been examined using 20 MeV bremsstrahlung. In this case, it was proved that better results can be achieved, because all interfering reactions were eliminated completely. (author) 14 refs.; 5 tabs

  13. Characterization of fly ash from bio and municipal waste

    DEFF Research Database (Denmark)

    Lima, Ana T.; Ottosen, Lisbeth M.; Pedersen, Anne Juul;

    2008-01-01

    Four different fly ashes are characterized in the present paper. The ashes differ in the original fuel type and were sampled at distinct plants. The investigation includes two different ashes from municipal solid waste incineration (with and without sorbents addition), a straw ash and an ash from...... on leaching characteristics, Cd is found mainly associated with carbonates in MSW fly ash and is associated with oxides in straw and co-combustion of wood and oil ash, while Cr is mainly associated with oxides in all studied fly ashes or with carbonates in straw ash. Among the studied parameters, crystalline...... minerals present in fly ash are discussed, measured by an XRD apparatus. Fuel is of main importance to determine Cd and Cr final concentration on fly ash, while flue gas temperature plays an important role as well. The goal of the present work is to underline the main parameters that determine fly ash...

  14. Preparation and characterization of Cobalt Sulfophthalocyanine/TiO{sub 2}/fly-ash cenospheres photocatalyst and study on degradation activity under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Huo Pengwei [School of Chemistry and Chemical Engineering, Jiangsu University, Jiangsu, Xuefu Road 301, Zhenjiang 212013 (China); Yan Yongsheng, E-mail: henanhuo@yahoo.com [School of Chemistry and Chemical Engineering, Jiangsu University, Jiangsu, Xuefu Road 301, Zhenjiang 212013 (China); Li Songtian; Li Huaming; Huang Weihong [School of Chemistry and Chemical Engineering, Jiangsu University, Jiangsu, Xuefu Road 301, Zhenjiang 212013 (China)

    2009-05-15

    Cobalt Sulfophthalocyanine (CoSPc) sensitized TiO{sub 2} sol samples were prepared through a Sol-Gel method using Cobalt Sulfophthalocyanine as a sensitizer. Loading and modified floating photocatalyst was prepared by hydrothermal method using fly-ash cenospheres as a carrier. The properties of the samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and UV-vis diffuse reflectance spectrum (DRS). Photocatalytic activity was studied by degrading wastewater of methylene blue under visible light. The results indicate that the fly-ash cenospheres are covered by modified TiO{sub 2} film which composed of the anatase, brookite and rutile misch crystal phase. CoSPc/TiO{sub 2}/fly-ash cenospheres samples have good catalytic activity under visible light, and have strong absorbency during 600-700 nm. The sensitization of CoSPc can enhance visible light catalytic activity of TiO{sub 2}/fly-ash cenospheres. The degradation rate of methylene blue reaches 73.36% in 180 min under the visible light illumination. But too much CoSPc can decrease its catalytic activity.

  15. Preparation and characterization of Cobalt Sulfophthalocyanine/TiO2/fly-ash cenospheres photocatalyst and study on degradation activity under visible light

    International Nuclear Information System (INIS)

    Cobalt Sulfophthalocyanine (CoSPc) sensitized TiO2 sol samples were prepared through a Sol-Gel method using Cobalt Sulfophthalocyanine as a sensitizer. Loading and modified floating photocatalyst was prepared by hydrothermal method using fly-ash cenospheres as a carrier. The properties of the samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and UV-vis diffuse reflectance spectrum (DRS). Photocatalytic activity was studied by degrading wastewater of methylene blue under visible light. The results indicate that the fly-ash cenospheres are covered by modified TiO2 film which composed of the anatase, brookite and rutile misch crystal phase. CoSPc/TiO2/fly-ash cenospheres samples have good catalytic activity under visible light, and have strong absorbency during 600-700 nm. The sensitization of CoSPc can enhance visible light catalytic activity of TiO2/fly-ash cenospheres. The degradation rate of methylene blue reaches 73.36% in 180 min under the visible light illumination. But too much CoSPc can decrease its catalytic activity.

  16. Fly ash reinforced thermoplastic vulcanizates obtained from waste tire powder.

    Science.gov (United States)

    Sridhar, V; Xiu, Zhang Zhen; Xu, Deng; Lee, Sung Hyo; Kim, Jin Kuk; Kang, Dong Jin; Bang, Dae-Suk

    2009-03-01

    Novel thermoplastic composites made from two major industrial and consumer wastes, fly ash and waste tire powder, have been developed. The effect of increasing fly ash loadings on performance characteristics such as tensile strength, thermal, dynamic mechanical and magnetic properties has been investigated. The morphology of the blends shows that fly ash particles have more affinity and adhesion towards the rubbery phase when compared to the plastic phase. The fracture surface of the composites shows extensive debonding of fly ash particles. Thermal analysis of the composites shows a progressive increase in activation energy with increase in fly ash loadings. Additionally, morphological studies of the ash residue after 90% thermal degradation shows extensive changes occurring in both the polymer and filler phases. The processing ability of the thermoplastics has been carried out in a Monsanto processability testing machine as a function of shear rate and temperature. Shear thinning behavior, typical of particulate polymer systems, has been observed irrespective of the testing temperatures. Magnetic properties and percolation behavior of the composites have also been evaluated. PMID:18838261

  17. Fly ash reinforced thermoplastic vulcanizates obtained from waste tire powder.

    Science.gov (United States)

    Sridhar, V; Xiu, Zhang Zhen; Xu, Deng; Lee, Sung Hyo; Kim, Jin Kuk; Kang, Dong Jin; Bang, Dae-Suk

    2009-03-01

    Novel thermoplastic composites made from two major industrial and consumer wastes, fly ash and waste tire powder, have been developed. The effect of increasing fly ash loadings on performance characteristics such as tensile strength, thermal, dynamic mechanical and magnetic properties has been investigated. The morphology of the blends shows that fly ash particles have more affinity and adhesion towards the rubbery phase when compared to the plastic phase. The fracture surface of the composites shows extensive debonding of fly ash particles. Thermal analysis of the composites shows a progressive increase in activation energy with increase in fly ash loadings. Additionally, morphological studies of the ash residue after 90% thermal degradation shows extensive changes occurring in both the polymer and filler phases. The processing ability of the thermoplastics has been carried out in a Monsanto processability testing machine as a function of shear rate and temperature. Shear thinning behavior, typical of particulate polymer systems, has been observed irrespective of the testing temperatures. Magnetic properties and percolation behavior of the composites have also been evaluated.

  18. Characteristics of MSWI fly ash during vitrification

    Institute of Scientific and Technical Information of China (English)

    TIAN Shu-lei; WANG Qi; WANG Qun-hui; MA Hong-zhi

    2009-01-01

    The vitrification characteristics of municipal solid waste incinerator (MSWI) fly ash were investigated. Effects of temperature on the binding efficiency of heavy metals, the change of chemical compositions and the weight loss of fly ash in the range of 800 - 1350 ℃ were studied. Toxicity Characteristic Leaching Procedure (TCLP) of the United States was used to analyze the leaching characteristics of heavy metals in fly ash and molten slag. Results indicate that chemical compositions, the weight loss of fly ash and the binding efficiency of heavy metals in fly ash have a tremendous change in the range of 1150 - 1260 ℃. The percentage of CaO, SiO2and AI203 increases with the increasing temperature, whereas it is contrary for SO3 , K2O, Na20 and CI; especially when the temperature is 1260 ℃, the percentage of these four elements decreases sharply from 43.72%to 0. 71%. The weight loss occurs obviously in the range of 1150 - 1260 ℃. Heavy metals of Pb and Cd are almost vaporized above 1000 ℃. Cr is not volatile and its binding efficiency can reach 100% below 1000 ℃. Resuits of TCLP indicate that the heavy metal content of molten slag is beyond stipulated limit values.

  19. Fly ash: Perspective resource for geo-polymer materials production

    Science.gov (United States)

    Kargin, Aleksey; Baev, Vladimir; Mashkin, Nikolay; Uglyanica, Andrey

    2016-01-01

    The present paper presents the information about the chemical and mineralogical composition of the ash and slag and their amounts at the dumps of the thermoelectric plants located in the city of Kemerovo. It is known that about 85% of ash and slag from the thermoelectric plants in Russia are removed by means of the hydraulic sluicing systems and only about 15% - by the systems of pneumatic ash handling. Currently, however, the transition from the "wet" ash removal systems to the "dry" ones is outlined. This process is quite logical since the fly ash has the higher reactivity compared with the hydraulic sluicing ash and therefore it is of the great interest for recycling and use. On the other hand, the recent trend is the increased use of fly ash in the production of geo-polymers due to their availability, workability and the increased life of the final product. The analysis is carried out to check the possibility of using the fly ash from various Kemerovo thermoelectric plants as a raw material for the production of the alkali-activated binder.

  20. Comparative study on the characteristics of fly ash and bottom ash geopolymers.

    Science.gov (United States)

    Chindaprasirt, Prinya; Jaturapitakkul, Chai; Chalee, Wichian; Rattanasak, Ubolluk

    2009-02-01

    This research was conducted to compare geopolymers made from fly ash and ground bottom ash. Sodium hydroxide (NaOH) and sodium silicate (Na(2)SiO(3)) solutions were used as activators. A mass ratio of 1.5 Na(2)SiO(3)/NaOH and three concentrations of NaOH (5, 10, and 15M) were used; the geopolymers were cured at 65 degrees C for 48 h. A Fourier transform infrared spectrometer (FT-IR), differential scanning calorimeter (DSC), and scanning electron microscope (SEM) were used on the geopolymer pastes. Geopolymer mortars were also prepared in order to investigate compressive strength. The results show that both fly ash and bottom ash can be utilized as source materials for the production of geopolymers. The properties of the geopolymers are dependent on source materials and the NaOH concentration. Fly ash is more reactive and produces a higher degree of geopolymerization in comparison with bottom ash. The moderate NaOH concentration of 10 M is found to be suitable and gives fly ash and bottom ash geopolymer mortars with compressive strengths of 35 and 18 MPa.

  1. Strength Properties of Fly Ash Based Geopolymer Concrete with Sea Sand

    OpenAIRE

    B. H. Shinde; Dr. K. N. Kadam

    2016-01-01

    The production of every ton of cement contributes to production of one ton of CO2. With the development of infra activities, the power sector activities are also increasing. The coal based power plant produces huge quantity of fly ash, which creates its disposal problems. However to some extent, the fly ash is used as partial substitution to cement. The alkali activated fly ash concrete (Geopolymer Concrete) proposed by Devidovits, shows considerable promise for application in construction in...

  2. Study on process parameters for activating fly ash with alkali by calcination%加碱煅烧活化粉煤灰工艺参数研究

    Institute of Scientific and Technical Information of China (English)

    吴勇勇; 周勇敏; 张苏伊

    2012-01-01

    The calcination process for activating fly ash with Na2CO3 as accessory ingredient was investigated.The concenta-tions of Si and A1 in the fly ash activated under different calcination conditions (calcination temperature and calcination time), that dissolved in the sodium hydroxide solution were measured by titering process.The phase composition of fly ash obtained under different calcination conditions (mass ratio of fly ash and sodium carbonate ) was characterized by XRD.The best process parameters were obtained as follows: calcination temperature was 875 X. .holding time was 1.5 h,and mass ratio of fly ash and sodium carbonate was 1:0.87.The products after calcination were mainly made up of soluble NaAlSiO4 and Na2SiO3,and the quartz and mullitein in the raw fly ash both almost disappeared.Therefore, the fly ash was activated adequately.%研究了以碳酸钠为助剂活化粉煤灰的煅烧工艺.采用滴定法测定不同煅烧条件(煅烧温度和煅烧时间)所得活化粉煤灰溶解在氢氧化钠溶液中的硅、铝浓度,并采用X射线衍射(XRD)表征不同煅烧条件(灰碱质量比)所得活化粉煤灰的物相组成,得出粉煤灰较佳煅烧工艺参数:煅烧温度为875℃,保温时间为1.5 h,粉煤灰与碳酸钠的质量比为1∶0.87.煅烧后的产物主要以可溶性的硅铝酸钠(NaAlSiO4)和硅酸钠(Na2SiO3)为主,原粉煤灰中的石英、莫来石基本消失,粉煤灰得到充分活化.

  3. Changeing of fly ash leachability after grinding

    Science.gov (United States)

    Lakatos, J.; Szabo, R.; Racz, A.; Banhidi, O.; Mucsi, G.

    2016-04-01

    Effect of grinding on the reactivity of fly ash used for geopolymer production was tested. Extraction technique using different alkaline and acidic solutions were used for detect the change of the solubility of elements due to the physical and mechano-chemical transformation of minerals in function of grinding time. Both the extraction with alkaline and acidic solution have detected improvement in solubility in function of grinding time. The enhancement in alkaline solution was approx. 100% in case of Si and Al. The acidic medium able to dissolve the fly ash higher manner than the alkaline, therefore the effect of grinding was found less pronounced.

  4. Physical cleaning of high carbon fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Gray, McMahan L.; Champagne, Kenneth J.; Soong, Yee; Killmeyer, Richard P. [National Energy Technology Laboratory, US Department of Energy, P.O. Box 10940, Cochran Mills Roads, 15236 Pittsburgh, PA (United States); Maroto-Valer, M. Mercedes; Andresen, John M. [The Energy Institute, The Pennsylvania State University, 405 Academic Activities Building, 16802-2308 University Park, PA (United States); Ciocco, Michael V.; Zandhuis, Paul H. [Parson Project Services Inc, National Energy Technology Laboratory, P.O. Box 618, 15129 Library, Pittsburgh, PA (United States)

    2002-04-20

    An industrial fly ash sample was cleaned by three different processes, which were triboelectrostatic separation, ultrasonic column agglomeration, and column flotation. The unburned carbon concentrates were collected at purities ranging up to 62% at recoveries of 62%. In addition, optical microscopy studies were conducted on the final carbon concentrates to determine the carbon forms (inertinite, isotropic coke and anisotropic coke) collected from these various physical-cleaning processes. The effects of the various cleaning processes on the production of different carbon forms from high carbon fly ashes will be discussed.

  5. Cementitious binder from fly ash and other industrial wastes

    Energy Technology Data Exchange (ETDEWEB)

    Singh, M.; Garg, M. [Central Building Research Inst., Roorkee (India)

    1999-03-01

    In this paper, investigations were undertaken to formulate cementitious binder by judicious blending of fly ash with Portland cement as well as by admixing fly ash with calcined phosphogypsum, fluorogypsum, lime sludge, and chemical activators of different finenesses. The effect of addition of calcined clay in these types of binders was studied. Data showed that cementitious binders of high compressive strength and water retentivity can be produced. The strength of masonry mortars increased with the addition of chemical activators. The strength development of binders takes place through formation of ettringite. C-S-H, and C{sub 4}AH{sub 13}. The binders are eminently suitable for partial replacement (up to 25%) of the cement in concrete without any detrimental affect on the strength. The results showed that fly ash can be used in the range from 45% to 70% in formulating these binders along with other industrial wastes to help in mitigating environmental pollution.

  6. Radon emanation fractions from concretes containing fly ash and metakaolin

    Energy Technology Data Exchange (ETDEWEB)

    Taylor-Lange, Sarah C., E-mail: taylorlanges@utexas.edu [Department of Civil, Architectural, and Environmental Engineering, 1 University Station C1748, The University of Texas at Austin, Austin, TX 78712 (United States); Juenger, Maria C.G. [Department of Civil, Architectural, and Environmental Engineering, 1 University Station C1748, The University of Texas at Austin, Austin, TX 78712 (United States); Siegel, Jeffrey A. [Department of Civil, Architectural, and Environmental Engineering, 1 University Station C1748, The University of Texas at Austin, Austin, TX 78712 (United States); Department of Civil Engineering, 35 St. George Street, University of Toronto, Toronto, ON, M5S 1A4 (Canada)

    2014-01-01

    Radon ({sup 222}Rn) and progenies emanate from soil and building components and can create an indoor air quality hazard. In this study, nine concrete constituents, including the supplementary cementitious materials (SCMs) fly ash and metakaolin, were used to create eleven different concrete mixtures. We investigated the effect of constituent radium specific activity, radon effective activity and emanation fraction on the concrete emanation fraction and the radon exhalation rate. Given the serious health effects associated with radionuclide exposure, experimental results were coupled with Monte Carlo simulations to demonstrate predictive differences in the indoor radon concentration due to concrete mixture design. The results from this study show that, on average, fly ash constituents possessed radium specific activities ranging from 100 Bq/kg to 200 Bq/kg and emanation fractions ranging from 1.1% to 2.5%. The lowest emitting concrete mixture containing fly ash resulted in a 3.4% reduction in the concrete emanation fraction, owing to the relatively low emanation that exists when fly ash is part of concrete. On average, the metakaolin constituents contained radium specific activities ranging from 67 Bq/kg to 600 Bq/kg and emanation fractions ranging from 8.4% to 15.5%, and changed the total concrete emanation fraction by roughly ± 5% relative to control samples. The results from this study suggest that SCMs can reduce indoor radon exposure from concrete, contingent upon SCM radionucleotide content and emanation fraction. Lastly, the experimental results provide SCM-specific concrete emanation fractions for indoor radon exposure modeling. - Highlights: • Fly ash or metakaolin SCMs can neutralize or reduce concrete emanation fractions. • The specific activity of constituents is a poor predictor of the concrete emanation fraction. • Exhalation from fly ash concretes represents a small fraction of the total indoor radon concentration.

  7. Radon emanation fractions from concretes containing fly ash and metakaolin

    International Nuclear Information System (INIS)

    Radon (222Rn) and progenies emanate from soil and building components and can create an indoor air quality hazard. In this study, nine concrete constituents, including the supplementary cementitious materials (SCMs) fly ash and metakaolin, were used to create eleven different concrete mixtures. We investigated the effect of constituent radium specific activity, radon effective activity and emanation fraction on the concrete emanation fraction and the radon exhalation rate. Given the serious health effects associated with radionuclide exposure, experimental results were coupled with Monte Carlo simulations to demonstrate predictive differences in the indoor radon concentration due to concrete mixture design. The results from this study show that, on average, fly ash constituents possessed radium specific activities ranging from 100 Bq/kg to 200 Bq/kg and emanation fractions ranging from 1.1% to 2.5%. The lowest emitting concrete mixture containing fly ash resulted in a 3.4% reduction in the concrete emanation fraction, owing to the relatively low emanation that exists when fly ash is part of concrete. On average, the metakaolin constituents contained radium specific activities ranging from 67 Bq/kg to 600 Bq/kg and emanation fractions ranging from 8.4% to 15.5%, and changed the total concrete emanation fraction by roughly ± 5% relative to control samples. The results from this study suggest that SCMs can reduce indoor radon exposure from concrete, contingent upon SCM radionucleotide content and emanation fraction. Lastly, the experimental results provide SCM-specific concrete emanation fractions for indoor radon exposure modeling. - Highlights: • Fly ash or metakaolin SCMs can neutralize or reduce concrete emanation fractions. • The specific activity of constituents is a poor predictor of the concrete emanation fraction. • Exhalation from fly ash concretes represents a small fraction of the total indoor radon concentration

  8. Application of Fly Ash from Solid Fuel Combustion in Concrete

    OpenAIRE

    Pedersen, Kim Hougaard; Dam-Johansen, Kim; Jensen, Anker Degn

    2008-01-01

    Application of Fly Ash from Solid Fuel Combustion in Concrete Kim H. Pedersen Abstract Industrial utilization of fly ash from pulverized coal combustion plays an important role in environmentally clean and cost effective power generation. Today, the primary market for fly ash utilization is as pozzolanic additive in the production of concrete. However, the residual carbon in fly ash can adsorb the air entraining admixtures (AEAs) added to enhance air entrainment in concrete in order to increa...

  9. Experimental research of non-burned fly-ash ceramsite

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yi-shun; ZHANG Chao; GUO Jin-min; ZHOU Shao-tong

    2005-01-01

    Selected non-burned method and took fly-ash as main material, together with lime and gypsum, to inspire the activity of volcanic ash, took a kind of poly-organics to replace the clay as binder, and then made small balls with machine, wrapped slurry twice and autoclaved 8 hours at normal atmosphere, made ceramsite in this way can endure higher compression strength. Comparing with common concrete, the ceramsite concrete is about 25% lighter on weight.

  10. Research on Adsorbent Using Modified Fly Ash for Campus Domestic Sewage Treatment

    Directory of Open Access Journals (Sweden)

    Li Jinping

    2016-01-01

    Full Text Available As a kind of extensive sources and low cost industrial waste, fly ash has many features, such as porosity, large surface area, adsorption capacity, chemical activity and weakly alkaline, which seem a wide prospect of application in wastewater treatment. This study proposed the acid modification test on fly ash. The effect of key factors including the particle size, pH, the dosage of fly ash, adsorption time and dosage of the modifier on domestic sewage removal efficiencies were evaluated. The optimum conditions and the corresponding removal efficiency were determined. The results show that the removal efficiency is increased firstly and steady subsequently with the increase of fly ash dosage, increased firstly and decreased subsequently with the increase of adsorption time, and increased firstly and decreased subsequently with the increase of pH value. The removal efficiency can up to 95.19% when 0.7 g fly ash added in 200 mL wastewater when the pH value was adjusted to 5 at the adsorption time of 20 min. And the best particle size of fly ash is 200 meshes, when used 2mol/L hydrochloride as modifier and soaked fly ash for 2h, and the ratio of hydrochloride and fly ash is 1mL / g, the effect is best. It also finds obviously that fly ash can have a better effect on removal efficiency than raw fly ash.

  11. Role of aluminous component of fly ash on the durability of Portland cement-fly ash pastes in marine environment

    International Nuclear Information System (INIS)

    The durability, of mixtures of two kinds of Spanish fly ashes from coal combustion (ASTM class F) with 0, 15 and 35% replacement of Portland cement by fly ash, in a simulated marine environment (Na2SO4+NaCl solution of equivalent concentration to that of sea water: 0.03 and 0.45 M for sulphate and chloride, respectively), has been studied for a period of 90 days. The resistance of the different mixtures to the attack was evaluated by means of the Koch-Steinegger test. The results showed that all the mixtures were resistant, in spite of the great amount of Al2O3 content of the fly ash. The diffusion of SO42-, Na+ and Cl- ions through the pore solution activated the pozzolanic reactivity of the fly ashes causing the corresponding microstructure changes, which were characterized by X-ray diffraction (XRD), mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). As a result, the flexural strength of the mixtures increased, principally for the fly ash of a lower particle size and 35% of addition

  12. FLY ASH RECYCLE IN DRY SCRUBBING

    Science.gov (United States)

    The paper describes the effects of fly ash recycle in dry scrubbing. (Previous workers have shown that the recycle of product solids improves the utilization of slaked lime--Ca(OH)2--for sulfur dioxide (SO2) removal by spray dryers with bag filters.) In laboratory-scale experimen...

  13. On the development of fly ash-based geopolymer concrete

    Energy Technology Data Exchange (ETDEWEB)

    Hardjito, D.; Wallah, S.E.; Sumajouw, D.M.J.; Rangan, B.V. [Widya Mandira Catholic University, Kupang (Indonesia). Dept. of Civil Engineering

    2004-12-01

    To reduce greenhouse gas emissions, efforts are needed to develop environmentally friendly construction materials. This paper presents the development of fly ash-based geopolymer concrete. In geopolymer concrete, a by-product material rich in silicon and aluminum, such as low-calcium (ASTM C 618 Class F) fly ash, is chemically activated by a high-alkaline solution to form a paste that binds the loose coarse and fine aggregates, and other unreacted materials in the mixture. The test results presented in this paper show the effects of various parameters on the properties of geopolymer concrete. The application of geopolymer concrete and future research needs are also identified.

  14. Alkali-aggregate reactivity of typical siliceious glass and carbonate rocks in alkali-activated fly ash based geopolymers

    Science.gov (United States)

    Lu, Duyou; Liu, Yongdao; Zheng, Yanzeng; Xu, Zhongzi; Shen, Xiaodong

    2013-08-01

    For exploring the behaviour of alkali-aggregate reactivity (AAR) in alkali-activated geopolymeric materials and assessing the procedures for testing AAR in geopolymers, the expansion behaviour of fly ash based geopolymer mortars with pure silica glass and typical carbonate rocks were studied respectively by curing at various conditions, i.e. 23°C and 38°C with relative humidity over 95%, immersed in 1M NaOH solution at 80°C. Results show that, at various curing conditions, neither harmful ASR nor harmful ACR was observed in geopolymers with the criteria specified for OPC system. However, with the change of curing conditions, the geopolymer binder and reactive aggregates may experience different reaction processes leading to quite different dimensional changes, especially with additional alkalis and elevated temperatures. It suggests that high temperature with additional alkali for accelerating AAR in traditional OPC system may not appropriate for assessing the alkali-aggregate reactivity behaviour in geopolymers designed for normal conditions. On the other hand, it is hopeful to control the dimensional change of geopolymer mortar or concrete by selecting the type of aggregates and the appropriate curing conditions, thus changing the harmful AAR in OPC into beneficial AAR in geopolymers and other alkali-activated cementitious systems.

  15. Influence of mechanical activation on the synthesis of Sr-Celsian employing a precursor mixture containing coal fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Badillo, C. M.; Lopez-Cuevas, J.; Rodriguez-Galicia, J. L.; Gutierrez-Chavarria, C. A.; Pech-Canul, M. I.

    2013-05-01

    Strontium aluminosilicate, SrAl{sub 2}Si{sub 2}O{sub 8} (SAS), was synthesized by a solid state reaction using coal fly ash (CFA) as main raw material. A precursor mixture of SrCO{sub 3}, CFA and Al{sub 2}O{sub 3} was mechanically-activated for times of up to 12 h using an attrition mill, and subsequently sintered at temperatures of 900-1300 degree centigrade. The CFA and the mechanical activation were employed with the aim to promote the transformation from the hexagonal (Sr-Hexacelsian) into the monoclinic (Sr-Celsian) polymorphic form of SAS, since the latter phase is associated with better physical and mechanical properties but the former tends to be the first one to appear. The mean particle size, the crystallite size and the temperature at the end of the curve of weight loss (Tf) decreased, while the specific surface area and the degree of amorphization increased, with increasing milling time. Samples milled for at least 4 h and then sintered at 1100 degree centigrade achieved full transformation into Sr-Celsian. The same result was obtained for sintering temperatures higher than 1100 degree centigrade, independently of milling time. An increment in both the milling time and the sintering temperature allowed us to improve the densification and the mechanical properties of the synthesized materials. (Author) 24 refs.

  16. Influence of mechanical activation on the synthesis of Sr-Celsian employing a precursor mixture containing coal fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Badillo, C. M.; Lopez-Cuevas, J.; Rodriguez-Galicia, J. L.; Gutierrez-Chavarria, C. A.; Pech-Canul, M. I.

    2013-06-01

    Strontium aluminosilicate, SrAl{sub 2}Si{sub 2}O{sub 8} (SAS), was synthesized by a solid state reaction using coal fly ash (CFA) as main raw material. A precursor mixture of SrCO{sub 3}, CFA and Al{sub 2}O{sub 3} was mechanically-activated for times of up to 12 h using an attrition mill, and subsequently sintered at temperatures of 900-1300 degree centigrade. The CFA and the mechanical activation were employed with the aim to promote the transformation from the hexagonal (Sr-Hexacelsian) into the monoclinic (Sr-Celsian) polymorphic form of SAS, since the latter phase is associated with better physical and mechanical properties but the former tends to be the first one to appear. The mean particle size, the crystallite size and the temperature at the end of the curve of weight loss (Tf) decreased, while the specific surface area and the degree of amorphization increased, with increasing milling time. Samples milled for at least 4 h and then sintered at 1100 degree centigrade achieved full transformation into Sr-Celsian. The same result was obtained for sintering temperatures higher than 1100 degree centigrade, independently of milling time. An increment in both the milling time and the sintering temperature allowed us to improve the densification and the mechanical properties of the synthesized materials. (Author)

  17. Flue gas desulfurization gypsum and fly ash

    International Nuclear Information System (INIS)

    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

  18. Synthesis of merlinoite from Chinese coal fly ashes and its potential utilization as slow release K-fertilizer

    OpenAIRE

    Li, Jing; Zhuang, Xinguo; Font, Oriol; Moreno, Natalia; Vallejo, V. Ramón; Querol, Xavier; Tobias, Aurelio

    2014-01-01

    This study focuses on the synthesis of merlinoite from Chinese coal fly ashes by KOH direct conversion method, with special emphasis on the application of synthetic merlinoite as fertilizer. These fly ashes were collected from two pulverized-coal combustion (PCC) power plants in Xinjiang, Northwest China. The synthesis results are influenced by fly ash characteristics and different synthesis conditions (KOH solution concentrations, activation temperature, time, and KOH/fly ash ratios). A high...

  19. Screening of Surface Medication Agents and Modification Mechanism of Fly Ash

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hong-bo; WEI Lu-bin

    2007-01-01

    The fly ash from Jixi power plant was treated with various surface modifiers. The surface properties of the modified fly ash, including active index wetting angle, were measured in this paper. The modified fly ash was filled into rubber to improve the rubber properties. The results of rubber tests indicate that the type of the surface modifiers has a great influence on the rubber reinforcing properties. The fly ash modified by titanate coupling agents exhibits the best performance in respect to rubber reinforcing properties. The test results show that the fly ash can take place of some decomposition material so that the dosage of decomposition in rubber can be reduced, resulting in the low producing cost of rubber and the low pollution of fly ash.

  20. 化学激发固硫灰的早期水化活性%Excitation of Chemical Activators on the Hydrating of CFBC Fly Ash

    Institute of Scientific and Technical Information of China (English)

    夏艳晴; 严云; 胡志华; 胡昌华; 雷秀坚

    2012-01-01

    采用激发剂单掺和复掺的方式对固硫灰的火山灰活性和自硬性进行激活,对比分析了固硫灰7d和28 d的抗压强度,同时利用水化热测量、XRD和红外(FT-IR)分析等方法分析激发剂对固硫灰早期水化活性的影响.结果表明:不同种类激发剂激发固硫灰早期活性的顺序为:生石灰>水玻璃>三乙醇胺>Na2SO4;Na2SO4能够有效地促进固硫灰中硬石膏的溶解析晶,当Na2SO4与TEA复掺时,可以避免Na2SO4激发固硫灰后期强度发展缓慢的缺点;在固硫灰中添加适量生石灰可以显著提高固硫灰活性;4种激发剂复掺时,固硫灰7d和28 d强度分别达到7 MPa和22 MPa,推荐采用复合激活方法激发固硫灰活性.%The pozzolanic and self-cementitious properties of CFBC fly ash with various chemical activators were investigated. The effect of different chemical activators and their different combinations on the mechanical properties of CFBC fly ash was evaluated based on the criteria of 7 d and 28 d compressive strengths of CFBC fly ash. Meanwhile,the influence of chemical activators on the early hydrating process and hydrated products of CFBC fly ash were analyzed with isothermal calorimeter method, XRD and IR.The results show that different activators obviously affect the strength of hardened CFBC fly ash paste and the degree of impact in order is as follows: lime>sodium silicate>TEA>Na2SO4; the addition of Na2SO4 promotes the dissolution of anhydrite and increases its hydration rate, composite activation of Na2SO4 and TEA can solve the question that compressive strengths of CFBC fly ash with adding Na2SO4 increases slowly; the addition of lime significantly improves the activity of CFBC fly ash; the combination of four activators mentioned above are recommended to use for increasing the activity of CFBC fly ash, resulting into the 7 d and 28 d compressive strength of the mortar is up to 7 MPa and 22 MPa,respectively.

  1. Heavy metal removal from MSWI fly ash by electrokinetic remediation coupled with a permeable activated charcoal reactive barrier

    Science.gov (United States)

    Huang, Tao; Li, Dongwei; Kexiang, Liu; Zhang, Yuewei

    2015-10-01

    This paper presents the investigations into the feasibility of the application of a remediation system that couples electrokinetic remediation (EKR) with the permeable reactive barrier (PRB) concept for municipal solid waste incineration (MSWI) fly ash with activated charcoal as the PRB material. The experimental results of this study showed that the proposed combined method can effectively improve the remediation efficiency and that the addition of the oxalic acid to the PRB media before the coupled system can further enhance the remediation process. In the optimization tests, the maximum removals of Zn, Pb, Cu and Cd were achieved under different experimental conditions. The voltage gradient and processing time were shown to have significant effects on the removal of Cu and Cd, whereas the addition of the oxalic acid had a more significant influence on the removal of Pb. Generally, the processing time is the most significant factor in changing the removal rates of HMs in the enhanced coupled system. In terms of the leaching toxicity, the specimen remediated by ENEKR + PRB showed the lowest leaching value for each HM in the S2 and S3 regions.

  2. Possibilities of municipal solid waste incinerator fly ash utilisation.

    Science.gov (United States)

    Hartmann, Silvie; Koval, Lukáš; Škrobánková, Hana; Matýsek, Dalibor; Winter, Franz; Purgar, Amon

    2015-08-01

    Properties of the waste treatment residual fly ash generated from municipal solid waste incinerator fly ash were investigated in this study. Six different mortar blends with the addition of the municipal solid waste incinerator fly ash were evaluated. The Portland cement replacement levels of the municipal solid waste incinerator fly ash used were 25%, 30% and 50%. Both, raw and washed municipal solid waste incinerator fly ash samples were examined. According to the mineralogical composition measurements, a 22.6% increase in the pozzolanic/hydraulic properties was observed for the washed municipal solid waste incinerator fly ash sample. The maximum replacement level of 25% for the washed municipal solid waste incinerator fly ash in mortar blends was established in order to preserve the compressive strength properties. Moreover, the leaching characteristics of the crushed mortar blend was analysed in order to examine the immobilisation of its hazardous contents. PMID:26060198

  3. The Future Resources for Eco-building Materials: II.Fly Ash and Coal Waste

    Institute of Scientific and Technical Information of China (English)

    LI Hui; XU Delong

    2009-01-01

    To use fly ash and coal waste effectively,the current technologies for reprocessing and recycling these wastes into eco-building materials were reviewed,such as utilizing fly ash as the component of fly ash cement and low heat cement after the processes of separation,removal of carbon remains and fine comminution,calcining coal waste into kaolin and meta-kaolin with suspension technology,and preparing clinkerless alkali-activated geopolymer materials with fly ash and meta-kaolin.

  4. Norm in coal, fly ash and cement

    International Nuclear Information System (INIS)

    Coal is technologically important materials being used for power generation and its cinder (fly ash) is used in manufacturing of bricks, sheets, cement, land filling etc. 222Rn (radon) and its daughters are the most important radioactive and potentially hazardous elements, which are released in the environment from the naturally occurring radioactive material (NORM) present in coal, fly ash and cement. Thus it is very important to carry out radioactivity measurements in coal, fly ash and cement from the health and hygiene point of view. Samples of coal and fly ash from different thermal power stations in northern India and various fly ash using establishments and commercially available cement samples (O.P.C. and P.P.C.) were collected and analyzed for radon concentration and exhalation rates. For the measurements, alpha sensitive LR-115 type II plastic track detectors were used. The radon concentration varied from 147 Bq/m3 to 443 Bq/m3, the radium concentration varied from 1.5 to 4.5 Bq/kg and radon exhalation rate varied from 11.8 mBq.kg-1.h-1 to 35.7 mBq.kg-1.h-1 for mass exhalation rate and from 104.5 mBq.m-2.h-1 to 314.8 mBq.m-2.h-1 for surface exhalation rate in coal samples. The radon concentration varied from 214 Bq/m3 to 590 Bq/m3, the radium concentration varied from 1.0 to 2.7 Bq/kg and radon exhalation rate varied from 7.8 mBq.kg-1.h-1 to 21.6 mBq.kg-1.h-1 for mass exhalation rate and from 138 mBq m-2h-1 to 380.6 mBq.m-2.h-1 for surface exhalation rate in fly ash samples. The radon concentration varied from 157.62 Bq/m3 to 1810.48 Bq/m3, the radium concentration varied from 0.76 Bq/kg to 8.73 Bq/kg and radon exhalation rate varied from 6.07 mBq.kg-1.hr-1 to 69.81 mBq.kg-1.hr-1 for mass exhalation rate and from 107.10 mBq.m-2.hr-1 to 1230.21 mBq.m-2.hr-1 for surface exhalation rate in different cement samples. The values were found higher in P.P.C. samples than in O.P.C. samples. (authors)

  5. Assessing fly ash treatment: Remediation and stabilization of heavy metals

    DEFF Research Database (Denmark)

    Lima, A.T.; Ottosen, Lisbeth M.; Ribeiro, Alexandra B.

    2012-01-01

    consider application to the soil. ST ash is the only residue that gets concentrations low enough to be reused, but its fertilizing value might be questioned. An alternative reuse for the three ashes is here preliminary tested, the combination of fly ash with mortar. Fly ashes have been substituted...... by cement fraction or aggregate fraction. Surprisingly, better compressive strengths were obtained by replacing the aggregate fraction. CW ashes presented promising results for the substitution of aggregate in mortar and possibly in concrete....

  6. Electrodialytic removal of Cd from biomass combustion fly ash suspensions

    OpenAIRE

    Kirkelund, Gunvor M.; Ottosen, Lisbeth M.; Damoe, Anne J.

    2013-01-01

    Due to relatively high concentrations of Cd, biomass combustion fly ashes often fail to meet Danish legislative requirements for recycling as fertilizer. In this study, the potential of using electrodialytic remediation for removal of Cd from four different biomass combustion fly ashes was investigated with the aim of enabling reuse of the ashes. The ashes originated from combustion of straw (two ashes), wood chips, and co-firing of wood pellets and fuel oil, respectively. A series of laborat...

  7. The evolution of strength and crystalline phases for alkali-activated ground blast furnace slag and fly ash-based geopolymers

    Energy Technology Data Exchange (ETDEWEB)

    Jae Eun Oh; Paulo J.M. Monteiro; Ssang Sun Jun; Sejin Choi; Simon M. Clark [University of California, Berkeley, CA (United States). Department of Civil and Environmental Engineering

    2010-02-15

    The increase in strength and evolution of crystalline phases in inorganic polymer cement, made by the alkali activation of slag, Class C and Class F fly ashes, was followed using compressive strength test and synchrotron X-ray diffraction. In order to increase the crystallinity of the product the reactions were carried out at 80{sup o}C. We found that hydrotalcite formed in both the alkali-activated slag cements and the fly ash-based geopolymers. Hydroxycancrinite, one member of the ABC-6 family of zeolites, was found only in the fly ash geopolymers. Assuming that the predominantly amorphous geopolymer formed under ambient conditions relates to the crystalline phases found when the mixture is cured at high temperature, we propose that the structure of this zeolitic precursor formed in Na-based high alkaline environment can be regarded as a disordered form of the basic building unit of the ABC-6 group of zeolites which includes poly-types such as hydroxycancrinite, hydroxysodalite and chabazite-Na.

  8. The evolution of strength and crystalline phases for alkali-activated ground blast furnace slag and fly ash-based geopolymers

    KAUST Repository

    Oh, Jae Eun

    2010-02-01

    The increase in strength and evolution of crystalline phases in inorganic polymer cement, made by the alkali activation of slag, Class C and Class F fly ashes, was followed using compressive strength test and synchrotron X-ray diffraction. In order to increase the crystallinity of the product the reactions were carried out at 80 °C. We found that hydrotalcite formed in both the alkali-activated slag cements and the fly ash-based geopolymers. Hydroxycancrinite, one member of the ABC-6 family of zeolites, was found only in the fly ash geopolymers. Assuming that the predominantly amorphous geopolymer formed under ambient conditions relates to the crystalline phases found when the mixture is cured at high temperature, we propose that the structure of this zeolitic precursor formed in Na-based high alkaline environment can be regarded as a disordered form of the basic building unit of the ABC-6 group of zeolites which includes poly-types such as hydroxycancrinite, hydroxysodalite and chabazite-Na. © 2009 Elsevier Ltd.

  9. Metallothionein response in earthworms Lampito mauritii (Kinberg) exposed to fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Maity, S.; Hattacharya, S.; Chaudhury, S. [Visva Bharati, Santini Ketan (India)

    2009-10-15

    Among pollutants, the coal fly ash occupies a significant position in industrial wastes. The fly ash matrix is a complex mixture of various organic (polyhalogenated compounds) and inorganic (Si, Al, Fe, As, Cd, Bi, Hg, etc.) chemicals. The application of fly ash for agricultural purposes and as landfills may lead to the contamination of the land with some of the toxic chemical compounds present in fly ash. Thus prior to the application of fly ash for developmental activities, it requires bio-monitoring and risk characterization. In order to achieve this objective adult Lampito mauritii were exposed to different proportions of fly ash in soil for 30 d and the concentrations of metallothionein in earthworm were assessed. The results revealed that up to 50% of fly ash amendment does not apparently harm the earthworm in respect of their survival and growth. A significant increase in tissue metallothionein level was recorded in L mauritii exposed to fly ash amended soil without tissue metal accumulation indicating that metallothionein is involved in scavenging of free radicals and reactive oxygen species metabolites. It is concluded that this biochemical response observed in L mauritii exposed to fly ash amended soil could be used in ecotoxicological field monitoring.

  10. Synthesis of activated carbon from oil fly ash for removal of H2S from gas stream

    Science.gov (United States)

    Aslam, Zaheer; Shawabkeh, Reyad A.; Hussein, Ibnelwaleed A.; Al-Baghli, Nadhir; Eic, Mladen

    2015-02-01

    Activated carbon (AC) is made from waste oil fly ash (OFA) which is produced in large quantities from power generation plants through combustion of heavy fuel oil. OFA contains ∼80% carbon that makes it suitable for producing AC by physicochemical treatments using a mixture of HNO3, H2SO4, and H3PO4 acids to remove non-carbonaceous impurities. The acid treated OFA is then activated by CO2 at 990 °C. The physico-chemical treatments of OFA have increased the surface area from 4 to 375 m2/g. Surface morphology and pore volume of AC are characterized by combined SEM and EDX techniques. Elemental analysis shows that sulfur content is reduced from 7.1 wt% in untreated OFA to 0.51 wt% for the treated OFA. The AC is further treated with HNO3 and NH4OH solutions in order to attach the carboxylic and amine groups on the surface, respectively. FTIR characterization is used to confirm the presence of the functional groups on the surface of AC at different stages of its development. The performance of functionalized AC samples is tested for the removal of H2S from a synthetic natural gas by carrying out breakthrough experiments. The results from these tests have shown maximum adsorption capacity of 0.3001 mg/g for NH4OH functionalized activated carbon with 86.43% regeneration efficiency. The ammonium hydroxide treated AC is found to be more effective for H2S removal than acid treated AC as confirmed by breakthrough experiments. The results indicate that the presence of more acidic functionalities on the surface reduces the H2S adsorption efficiency from the gas mixture.

  11. Production of ceramics from coal fly ash

    Directory of Open Access Journals (Sweden)

    Angjusheva Biljana

    2012-01-01

    Full Text Available Dense ceramics are produced from fly ash from REK Bitola, Republic of Macedonia. Four types of fly ash from electro filters and one from the collected zone with particles < 0.063 mm were the subject of this research. Consolidation was achieved by pressing (P= 133 MPa and sintering (950, 1000, 1050 and 11000C and heating rates of 3 and 100/min. Densification was realized by liquid phase sintering and solid state reaction where diopside [Ca(Mg,Al(Si,Al2O6] was formed. Ceramics with optimal properties (porosity 2.96±0.5%, bending strength - 47.01±2 MPa, compressive strength - 170 ±5 MPa was produced at 1100ºC using the heating rate of 10ºC/min.

  12. Influence of Biofuel Combustion Fly Ash on the Properties of Concrete

    Directory of Open Access Journals (Sweden)

    Nagrockienė Džigita

    2015-12-01

    Full Text Available Cement as the binding agent in the production of concrete can be replaced with active mineral admixtures. Biofuel combustion fly ash is one of such admixtures. Materials used for the study include Portland cement CEM I 42.5 R, sand of 0/4 fraction, gravel of 4/16 fraction, biofuel fly ash, superplasticizer, and water. Six compositions of concrete were designed by replacing 0 %, 5 %, 10 %, 15 % 20 %, and 25 % of cement with biofuel fly ash. The article analyses the effect of biofuel fly ash content on the properties of concrete. The tests revealed that the increase of biofuel fly ash content up to 20 % increases concrete density and compressive strength after 7 and 28 days of curing and decreases water absorption, with corrected water content by using plasticizing admixture. It has been found that concrete where 20 % of cement is replaced by biofuel ash has higher frost resistance.

  13. Hydrothermal processing of new fly ash cement

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, W.; Roy, D.M. (Materials Research Lab., Pennsylvania State Univ., University Park, PA (United States))

    1992-04-01

    The recent Mount Pinatubo volcanic eruption in the Philippines, in which at least 268 people died, shows that volcanic eruptions can be highly destructive. The eruption shot ash and debris over the countryside; six towns near the volcano faced a high risk of devastating mudslides, and nearly 2000 U.S. service members and their families were evacuated from two nearby military bases. However, this paper reports that not all the consequences of volcanic eruptions are bad. Under hydrothermal conditions, volcanic ash can be transformed into zeolitic tuff and, eventually, into clay minerals that constitute agricultural soils. The Materials Research Laboratory (MRL) has recently used some artificial pozzolanas (fly ash) that when mixed with lime, under hydrothermal conditions, also produced a new type of cementitious material. This was categorized as a new fly ash cement. The formation of a new hydrothermally treated wood-fiber-reinforced composite has also been demonstrated. It is apparent, however, that with respect to concerns about detailed knowledge of the reactivity of calcium silicate-based materials under hydrothermal conditions, the application of the technology far outweighs the understanding of the underlying principles of reactivity. It would seem that an understanding of reactions on the molecular level is just beginning, and that work on hydrothermal reactions is still a potentially lucrative area of research.

  14. Electrodialytic removal of Cd from biomass combustion fly ash

    DEFF Research Database (Denmark)

    Pedersen, Anne Juul; Ottosen, Lisbeth M.; Simonsen, Peter;

    2004-01-01

    Due to a high concentration of Cd, biomass combustion fly ash often fails to meet the Danish legislative requirements for recycling on agricultural fields. In this work the potential of using the method Electrodialytic Remediation to reduce the concentration of Cd in different biomass combustion...... fly ashes was studied. Four fly ashes were investigated, originating from combustion of straw (two ashes), wood chips, and co-firing of wood pellets and fuel oil, respectively. One of the straw ashes had been pre-washed and was obtained suspended in water, the other ashes were obtained naturally dry....... The initial Cd concentration in the ashes varied between 8.8 mg Cd/kg DM (co-firing ash) and 64 mg Cd/kg DM (pre-washed straw ash), and pH varied from 3.7 to 13.3. In spite of large differences in ash characteristics, the electrodialytic remediation experiments indicated a good remediation potential for all...

  15. Environmental impact of using fly ash in concrete

    Energy Technology Data Exchange (ETDEWEB)

    1978-09-01

    An attempt was made to estimate the chemical composition of fly ash using the known chemical composition of coals from numerous regions of the country and the known behavior of elements in a limited number of coal and fly-ash samples. This technique assumes that each element in every piece of coal in the United States partitions itself into fly ash to the same extent and leaches from fly ash at the same rate. Using these limited data, enrichment factors were then calculated by dividing the composition in the fly ash by the composition in the corresponding coal samples. These enrichment factors were then applied to all of the coal samples for which chemical compositions were available to estimate the chemical composition of the fly ash.

  16. Geoenvironmental aspects of coal refuse-fly ash blends

    OpenAIRE

    Albuquerque, Allwyn J.

    1994-01-01

    The separate land disposal of coal refuse and fly ash presents difficulties throughout the Appalachian region, both in terms of disposal costs per acre and in terms of its potential environmental impacts on soil, ground water, revegetation, and slope stability. The purpose of this study was to determine how fly ash addition to coal refuse would impact on certain geotechnical properties of the refuse disposal piles, and whether the refuse-fly ash blends would be suitable as co-d...

  17. The Cement Solidification of Municipal Solid Waste Incineration Fly Ash

    Institute of Scientific and Technical Information of China (English)

    HOU Haobo; HE Xinghua; ZHU Shujing; ZHANG Dajie

    2006-01-01

    The chemical composition, the content and the leachability of heavy metals in municipal solid waste incineration ( MSWI) fly ash were tested and analyzed. It is shown that the leachability of Pb and Cr exceeds the leaching toxicity standard, and so the MSWI fly ash is considered as hazardous waste and must be solidifled. The effect of solidifying the MSWI fly ash by cement was studied, and it is indicated that the heavy metals can be well immobilized if the mass fraction of the fly ash is appropriate. The heavy metals were immobilized within cement hydration products through either physical fixation, substitution, deposition or adsorption mechanisms.

  18. Experimental Study on Volume for Fly Ash of Building Block

    Directory of Open Access Journals (Sweden)

    Ling Wang

    2013-04-01

    Full Text Available Fly ash is a waste substance from thermal power plants, steel mills, etc. That is found in abundance in the world. It has polluted the environment, wasting the cultivated land. This study introduces an experimental research on fly ash being reused effectively, the study introduces raw materials of fly ash brick, production process and product inspection, fly ash content could be amounted to 40%~75%. High doping fly ash bricks are manufactured, which selects wet fly ash from the power plants, adding aggregate with reasonable ratio and additives with reasonable dosage and do the experimental research on manufacture products for properties, production technology and selection about technology parameter of production equipment. Index of strength grade and freezing-thawing resisting etc and the high doping fly ash brick building which we are working on can achieve the national standard on building materials industry. Based on the tests, this achievement of research has a very wide practical prospect in using fly ash, industrial waste residue, environmental protection and reducing the cost of enterprises. The efficient reuse of fly ash from coal boiler and power plants has very vital significance of protecting the environment, benefiting descendants and developing of circular economy.

  19. STUDY ON CORROSION RESISTANCE OF REBAR IN HYBRID GRINDING FLY ASH-LIME SILICATE CONCRETE

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The corrosion resistance of rebar in fly ash-lime sili cate concrete as well as its marco properties and pore distribution is investiga ted.The results show that the fly ash is activated, the compressive strength of the silicate concrete is strengthened and its pore structure is modified after f ly ash and lime being hybrid ground.Also the corrosion resistance of rebar in the silicate concrete is improved.

  20. Improvements of nano-SiO2 on sludge/fly ash mortar.

    Science.gov (United States)

    Lin, D F; Lin, K L; Chang, W C; Luo, H L; Cai, M Q

    2008-01-01

    Sewage sludge ash has been widely applied to cementitious materials. In this study, in order to determine effects of nano-SiO(2) additives on properties of sludge/fly ash mortar, different amounts of nano-SiO(2) were added to sludge/fly ash mortar specimens to investigate their physical properties and micro-structures. A water-binding ratio of 0.7 was assigned to the mix. Substitution amounts of 0%, 10%, 20%, and 30% of sludge/fly ash (1:1 ratio) were proposed. Moreover, 0%, 1%, 2%, and 3% of nano-SiO(2) was added to the mix. Tests, including SEM and compressive strength, were carried out on mortar specimens cured at 3, 7, and 28 days. Results showed that sludge/fly ash can make the crystals of cement hydration product finer. Moreover, crystals increased after nano-SiO(2) was added. Hence, nano-SiO(2) can improve the effects of sludge/fly ash on the hydration of mortar. Further, due to the low pozzolanic reaction active index of sludge ash, early compressive strengths of sludge/fly ash mortar were decreased. Yet, nano-SiO(2) could help produce hydration crystals, which implies that the addition of nano-SiO(2) to mortar can improve the influence of sludge/fly ash on the development of the early strength of the mortar.

  1. EFFECTS OF FLY ASH ON MERCURY OXIDATION DURING POST COMBUSTION CONDITIONS

    Energy Technology Data Exchange (ETDEWEB)

    Glenn A. Norton; Hongqun Yang; Robert C. Brown; Dennis L. Laudal; Grant E. Dunham; John Erjavec; Joseph M. Okoh

    2002-01-31

    Tests were performed in simulated flue gas streams using fly ash from the electrostatic precipitators of two full-scale utility boilers. One fly ash was from a Powder River Basin (PRB) coal, while the other was from Blacksville coal. Elemental Hg was injected upstream from samples of fly ash loaded onto filters housed in an oven at 120 or 180 C. Concentrations of oxidized and elemental Hg downstream from the filters were determined using the Ontario Hydro method. The gas stream composition and whether or not ash was present in the gas stream were the two most important variables affecting Hg oxidation. The presence of HCl, NO, NO{sub 2}, and SO{sub 2} were all important with respect to Hg oxidation, with NO{sub 2} and HCl being the most important. The presence of NO suppressed Hg oxidation in these tests. Although the two fly ashes were chemically and mineralogically diverse, there were generally no large differences in catalytic potential (for oxidizing Hg) between them. Similarly, no ash fraction appeared to be highly catalytic relative to other ash fractions. This includes fractions enriched in unburned carbon and fractions enriched in iron oxides. Although some differences of lesser magnitude were observed in the amount of oxidized Hg formed, levels of oxidized Hg generally tracked well with the surface areas of the different ashes and ash fractions. Therefore, although the Blacksville fly ash tended to show slightly more catalytic activity than the PRB fly ash, this could be due to the relatively high surface area of that ash. Similarly, for Blacksville fly ash, using nonmagnetic ash resulted in more Hg oxidation than using magnetic ash, but this again tracked well with the relative surface areas of the two ash fractions. Test results suggest that the gas matrix may be more important in Hg oxidation chemistry than the fly ash composition. Combustion tests were performed in which Blacksville and PRB fly ashes were injected into filtered (via a baghouse with

  2. Illinois basin coal fly ashes. 2. Equilibria relationships and qualitative modeling of ash-water reactions

    Science.gov (United States)

    Roy, W.R.; Griffin, R.A.

    1984-01-01

    Alkaline and acidic Illinois Basin coal fly ash samples were each mixed with deionized water and equilibrated for about 140 days to simulate ash ponding environments. Common to both equilibrated solutions, anhydrite solubility dominated Ca2+ activities, and Al3+ activities were in equilibrium with both matrix mullite and insoluble aluminum hydroxide phases. Aqueous silica activities were controlled by both mullite and matrix silicates. The pH of the extract of the acidic fly ash was 4.1 after 24 h but increased to a pH value of 6.4 as the H2SO4, assumed to be adsorbed to the particle surfaces, was exhausted by the dissolution of matrix iron oxides and aluminosilicates. The activities of aqueous Al3+ and iron, initially at high levels during the early stages of equilibration, decreased to below analytical detection limits as the result of the formation of insoluble Fe and Al hydroxide phases. The pH of the extract of the alkaline fly ash remained above a pH value of 10 during the entire equilibration interval as a result of the hydrolysis of matrix oxides. As with the acidic system, Al3+ activities were controlled by amorphous aluminum hydroxide phases that began to form after about 7 days of equilibration. The proposed mechanisms and their interrelations are discussed in addition to the solubility diagrams used to deduce these relationships. ?? 1984 American Chemical Society.

  3. Fly ash as an adsorbent for textile dyes from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Khan, B.; Gupta, P.; Jala, S.; Goyal, D. [Thapar Institute of Engineering and Technology, Patiala (India). Dept. of Biotechnology and Environmental Sciences

    2003-07-01

    Fly ash is a solid waste generated as a result of combustion of coal and is of three types: the ESP (electrostatic precipitator) ash, bottom ash, and pond ash. Decolorization of two triphenylmethane dyes (crystal violet and malachite green) and one azo dye (congo red) was tried using the ESP fly ash in bath and column mode. Decolorization of 20 ppm of crystal violet and 100 ppm of malachite green occurred to the extent of 86% and 84% respectively, in batch mode. In columns packed with fly ash, 100 ppm of inlet solution of congo red and decolorized by 84%, at a flow rate of 2.0 ml/hour of packed bed column. When fly ash was mixed with activated charcoal in the ratio of 8:2, almost complete decolorization of the dye solution was observed, and the heavy metal content in the resulting colourless effluent was within permissible limits. This suggested that a combination of fly ash and activated charcoal can lead to replacement of nearly 80% of the activated charcoal, which can be a direct saving in operation costs along with gainful utilization of fly ash. 21 refs., 1 fig., 2 tabs.

  4. The Study of Intensity Performance of Alkali-Activated Fly Ash%碱激发粉煤灰力学性能的研究

    Institute of Scientific and Technical Information of China (English)

    胡楠楠; 李柱凯

    2012-01-01

    以氢氧化钠、水玻璃及水泥对粉煤灰(掺入一定量氧化钙)进行活性激发,采用蒸汽养护制度在80℃的条件下对粉煤灰试样进行蒸汽养护,研究水灰比、碱激发剂的种类、碱的掺量等因素对碱激发粉煤灰的强度发展规律。研究结果表明:水灰比对碱激发粉煤灰的强度发挥有很大的作用,当达到成型要求时其适宜的水灰比一般为0.38;复掺比单掺的效果好,其中氢氧化钠和水泥的复掺效果优于水玻璃和水泥的复掺效果;水玻璃和氢氧化钠作为激发剂激发粉煤灰时的最佳掺加量为10%。%The development principle of intensity of alkali-activated fly ash with water cement ration,the variation of their alkali type,content of alkali by NaOH,sodium silicate and cement activating fly ash(mix in CaO) on condation at 80 ℃ steam conserve was studied.The results showed that water cement ration had large effect on alkali-activated fly ash intensity,feasible water cement ration was 0.38 while it was fit for molding;together blending was superior to solely blending,the activated effect of NaOH and cement together blending was superior to sodium silicate and cement blending together.The best content of sodium silicate and NaOH was 10%when they used as alkali-activated reagent to solely activate the fly ash.

  5. Determination of anisotropy and multimorphology in fly ash based geopolymers

    Science.gov (United States)

    Khan, M. Irfan; Azizli, Khairun; Sufian, Suriati; Man, Zakaria; Siyal, Ahmer Ali; Ullah, Hafeez

    2015-07-01

    In this study, Malaysian coal fly ash-based geopolymers were investigated for its morphology and chemical composition using scanning electron microscopy coupled with energy dispersive X-rays (SEM-EDX). Geopolymer was synthesized using sodium hydroxide as activator. SEM studies revealed multiphasous structure of the material, composed of geopolymeric gel, partially reacted fly ashparticles and selectively leached particles. EDX analysis confirmed the chemical composition of different regions. Infra red spectroscopic studies supported the SEM-EDX analysis by confirming presence of unreacted quartzite and mullite in geopolymers. It is concluded that geopolymers possese a non uniform chemistry through out the structure.

  6. Determination of anisotropy and multimorphology in fly ash based geopolymers

    Energy Technology Data Exchange (ETDEWEB)

    Khan, M. Irfan, E-mail: mirfanwazir@gmail.com; Azizli, Khairun, E-mail: khairun-azizli@petronas.com.my; Sufian, Suriati, E-mail: suriati@petronas.com.my; Man, Zakaria, E-mail: zakaman@petronas.com.my; Siyal, Ahmer Ali, E-mail: ahmersiyal@gmail.com; Ullah, Hafeez, E-mail: Hafeez-wazir@yahoo.com [Department of Chemical Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750, Tronoh, Perak (Malaysia)

    2015-07-22

    In this study, Malaysian coal fly ash-based geopolymers were investigated for its morphology and chemical composition using scanning electron microscopy coupled with energy dispersive X-rays (SEM-EDX). Geopolymer was synthesized using sodium hydroxide as activator. SEM studies revealed multiphasous structure of the material, composed of geopolymeric gel, partially reacted fly ashparticles and selectively leached particles. EDX analysis confirmed the chemical composition of different regions. Infra red spectroscopic studies supported the SEM-EDX analysis by confirming presence of unreacted quartzite and mullite in geopolymers. It is concluded that geopolymers possese a non uniform chemistry through out the structure.

  7. Geological behavior of wet outflow deposition fly ash

    Institute of Scientific and Technical Information of China (English)

    周德泉; 赵明华; 刘宏利; 周毅; 严聪

    2008-01-01

    The geological behaviors of wet outflow deposition fly ash were investigated, including the feature of in-situ single and even bridge cone penetration test (CPT) curves, the change of the penetration parameters and vane strength with the increase of depth and the difference of the penetration resistance on and down the water level. Drilling, CPT and vane shear test were carried out in silty clay, fine sand, and fly ash of the ash-dam. The CPT curves of the fly ash do not show a critical depth. The cone resistance (qc) of the fly ash is smaller than that of silty clay or sand; the friction resistance is smaller than that of filling silty clay, similar to that of deposition silty clay or more than that of fine sand; the friction ratio is smaller than that of filling silty clay, or more than that of deposition silty clay or much more than that of fine sand. The specific penetration resistance (ps) is similar to that of filling silty clay, or more than that of deposition silty clay. There is a clear interface effect between the deposition fly ash and the clay. Interface effect of ps-h curve at the groundwater table is clear, and ps of the fly ash reduces significantly under the table. The vane strength of the fly ash increases as the depth increases. The deposition fly ash with wet outflow is similar to silt in the geological behavior.

  8. Geopolymerisation of fly ashes with waste aluminium anodising etching solutions.

    Science.gov (United States)

    Ogundiran, M B; Nugteren, H W; Witkamp, G J

    2016-10-01

    Combined management of coal combustion fly ash and waste aluminium anodising etching solutions using geopolymerisation presents economic and environmental benefits. The possibility of using waste aluminium anodising etching solution (AES) as activator to produce fly ash geopolymers in place of the commonly used silicate solutions was explored in this study. Geopolymerisation capacities of five European fly ashes with AES and the leaching of elements from their corresponding geopolymers were studied. Conventional commercial potassium silicate activator-based geopolymers were used as a reference. The geopolymers produced were subjected to physical, mechanical and leaching tests. The leaching of elements was tested on 28 days cured and crushed geopolymers using NEN 12457-4, NEN 7375, SPLP and TCLP leaching tests. After 28 days ambient curing, the geopolymers based on the etching solution activator showed compressive strength values between 51 and 84 MPa, whereas the commercial potassium silicate based geopolymers gave compressive strength values between 89 and 115 MPa. Based on the regulatory limits currently associated with the used leaching tests, all except one of the produced geopolymers (with above threshold leaching of As and Se) passed the recommended limits. The AES-geopolymer geopolymers demonstrated excellent compressive strength, although less than geopolymers made from commercial activator. Additionally, they demonstrated low element leaching potentials and therefore can be suitable for use in construction works.

  9. Durability Study on High Calcium Fly Ash Based Geopolymer Concrete

    OpenAIRE

    Ganesan Lavanya; Josephraj Jegan

    2015-01-01

    This study presents an investigation into the durability of geopolymer concrete prepared using high calcium fly ash along with alkaline activators when exposed to 2% solution of sulfuric acid and 5% magnesium sulphate for up to 45 days. The durability was also assessed by measuring water absorption and sorptivity. Ordinary Portland cement concrete was also prepared as control concrete. The grades chosen for the investigation were M20, M40, and M60. The alkaline solution used for present study...

  10. A comparison between sludge ash and fly ash on the improvement in soft soil.

    Science.gov (United States)

    Lin, Deng-Fong; Lin, Kae-Long; Luo, Huan-Lin

    2007-01-01

    In this study, the strength of soft cohesive subgrade soil was improved by applying sewage sludge ash as a soil stabilizer. Test results obtained were compared with earlier tests conducted on soil samples treated with fly ash. Five different proportions of sludge ash and fly ash were mixed with soft cohesive soil, and tests such as pH value, compaction, California bearing ratio, unconfined compressive strength (UCS), and triaxial compression were performed to understand soil strength improvement because of the addition of both ashes. Results indicate that pH values increase with extending curing age for soil with sludge ash added. The UCS of sludge ash/soil were 1.4-2 times better than untreated soil. However, compressive strength of sludge ash/soil was 20-30 kPa less than fly ash/soil. The bearing capacities for both fly ash/soil and sludge ash/soil were five to six times and four times, respectively, higher than the original capacity. Moreover, the cohesive parameter of shear strength rose with increased amounts of either ash added. Friction angle, however, decreased with increased amounts of either ash. Consequently, results show that sewage sludge ash can potentially replace fly ash in the improvement of the soft cohesive soil. PMID:17269231

  11. The use of neutron activation analysis for the study of environmental risks associated with the fly ash from burning Polish coals

    International Nuclear Information System (INIS)

    The work oriented towards assessment of environmental risk associated with the emission of fly-ash into atmosphere and its storage on solid waste depositories included: 1. Elaboration of the INAA procedure for the determination of 20-24 elements in the fly-ashes. This method was next used for the analysis of fly-ashes from three different Polish power stations working on hard coal. 2. Studies on leaching of trace elements from neutron irradiated fly-ash by water and H2SO4 solution (pH=2.5) simulating acid rain. The results were compared with analogous experiments in which elements leached from non-irradiated fly-ash were determined by AAS and spectrophotometry. 3. Preparation and certification on the basis of an international intercomparison of the new Polish CRM - fine fly-ash (CTA-FFA-1). Although the certification is still not completed it is almost certain that it will be possible to establish ''recommended values'' for at least 34 elements and ''information values'' for another 10 to 16 ones. (author). 11 refs, 5 figs, 4 tabs

  12. Potential fly-ash utilization in agriculture: A global review

    Institute of Scientific and Technical Information of China (English)

    Manisha Basu; Manish Pande; P.B.S. Bhadoria; S.C. Mahapatra

    2009-01-01

    Though in last four decades various alternate energy sources have come into the limelight, the hyperbolic use of coal as a prime energy source cannot be counterbalanced. Disposal of high amount of fly-ash from thermal power plants absorbs huge amount of water, energy and land area by ash ponds. In order to meet the growing energy demand, various environmental, economic and social problems associated with the disposal of fly-ash would continue to increase. Therefore, fly-ash management would remain a great concern of the century. Fly-ash has great potentiality in agriculture due to its efficacy in modification of soil health and crop performance. The high concentration of elements (K, Na, Zn, Ca, Mg and Fe) in fly-ash increases the yield of many agricultural crops. But compared to other sectors, the use of fly-ash in agriculture is limited. An exhaustive review of numerous studies of last four decades took place in this paper, which systematically covers the importance, scope and apprehension regarding utilization of fly-ash in agriculture. The authors concluded that though studies have established some solutions to handle the problems of radioactivity and heavy metal content in flyash, long-term confirmatory research and demonstration are necessary. This paper also identified some areas, like proper handling of dry ash in plants as well as in fields, ash pond management (i.e., faster decantation, recycling of water, vertical expansion rather than horizontal), monitoring of soil health, crop quality, and fate of fly-ash in time domain, where research thrust is required. Agricultural lime application contributes to global warming as Intergovernmental Panel on Climate Change (IPCC) assumes that all the carbon in agricultural lime is finally released as CO2to the atmosphere. It is expected that use of fly-ash instead of lime in agriculture can reduce net CO2emission, thus reduce global warming also.

  13. A fly ash and shale fired brick production line

    Institute of Scientific and Technical Information of China (English)

    ZhuYali

    2005-01-01

    The article describes the fly ash and shale fired brick production line with annual output of 1250 million bricks, designed by Xi'an Research and Design Institute of Wall and Roof Material, commissioned by QinDian Building Material Subcompany, and set an example for using fly ash and shale in China.

  14. Multinuclear NMR approach to coal fly ash characterization

    Energy Technology Data Exchange (ETDEWEB)

    Netzel, D.A.

    1991-09-01

    This report describes the application of various nuclear magnetic resonance (NMR) techniques to study the hydration kinetics and mechanisms, the structural properties, and the adsorption characteristics of coal fly ash. Coal fly ash samples were obtained from the Dave Johnston and Laramie River electric power generating plants in Wyoming. Hydrogen NMR relaxation times were measured as a function of time to observe the kinetics of hydration for the two coal fly ashes at different temperatures and water-to-cement ration. The kinetic data for the hydrated coal fly ashes were compared to the hydration of portland cement. The mechanism used to describe the kinetic data for the hydration of portland cement was applied, with reservation, to describe the hydration of the coal fly ashes. The results showed that the coal fly ashes differ kinetically from that of portland cement and from each other. Consequently, both coal fly ashes were judged to be poorer cementitious materials than portland cement. Carbon-13 NMR CP/MAS spectra were obtained for the anhydrous coal fly ashes in an effort to determine the type of organic species that may be present, either adsorbed on the surface or entrained.

  15. A study of fly ash-lime granule unfired brick

    Energy Technology Data Exchange (ETDEWEB)

    P. Chindaprasirt; K. Pimraksa [Khon Kaen University (Thailand). Department of Civil Engineering

    2008-02-15

    In this paper, the properties of fly ash-lime granule unfired bricks are studied. Granules were prepared from mixtures of fly ash and lime at fly ash to hydrated lime ratios of 100:0 (Ca/Si = 0.2), 95:5 (Ca/Si = 0.35) and 90:10 (Ca/Si = 0.5). After a period of moist curing, the microstructure and mineralogy of the granules were studied. Microstructure examination reveals that new phases in the form of needle-like particles are formed at the surface of granule. The granules were used to make unfired bricks using hydrothermal treatment at temperature of 130 {+-} 5{sup o}C and pressure of 0.14 MPa. The microstructures, mineralogical compositions, mechanical properties and environmental impact of bricks were determined. The results reveal that the strengths of unfired bricks are dependent on the fineness of fly ash. The strength is higher with an increase in fly ash fineness. The strengths of the fly ash-lime granule unfired brick are excellent at 47.0-62.5 MPa. The high strength is due to the formation of new products consisting mainly of hibschite and Al-substituted 11 {angstrom} tobermorite. The main advantage of utilization of granule is the ability to increase the pozzolanic reaction of fly ash through moisture retained in the granule. In addition, the heavy elements, in particular Cd, Ni, Pb and Zn are efficiently retained in the fly ash-lime granule unfired brick.

  16. Speciation of arsenic and selenium during leaching of fly ash

    NARCIS (Netherlands)

    Hoek, E.E. van der

    1995-01-01

    The leaching (release) of large amounts of oxyanions, such as those of arsenic and selenium, is an major environmental problem when it comes to the disposal or use of coal fly ash. To predict environmentally safe conditions for the disposal or use of fly ash in, for example, construction materials,

  17. Stabilization of Fly Ash Deposits through Selected Cereal Crops

    Directory of Open Access Journals (Sweden)

    Florica Morariu

    2012-10-01

    Full Text Available Fly ash, a waste product from burning coal in power plants, occupies important spaces and is a major harm forenvironment: water, air, soil and associated ecosystems. New deposits do not have available nutrients for plantgrowth. The study presents a process of stimulating growth of oats in deposits of fly ash, which eliminates listed.Phytostabilization of new deposit is fast after fertilization with sewage sludge-based compost in the presence/absence of native or modified volcanic tuff with grain species, Avena sativa L., and variety Lovrin 1. Experimentalstudies have shown the species adaptability to climatic conditions and a growth rate until the maturity correlated withtype of treatment of upper layers of fly ash deposit. Fly ash with sewage sludge compost treatment 50 t/hadetermined the growth with 75% of the amount of grains vs. the amount of grains harvested from untreated fly ash.Fly ash with sewage sludge compost mixed with modified indigenous volcanic tuff 2.5 t/ha treatment determined thegrowth with 80% vs. the amount of grains harvested from untreated fly ash. If oat straw harvested from fertilizedvariant without modified indigenous volcanic tuff increases in weight are 30% and for fertilized variant in thepresence of tuff increases in weight are 39.8% vs. quantities harvested from untreated fly ash.

  18. Sintering of MSWI fly ash by microwave energy.

    Science.gov (United States)

    Chou, Sun-Yu; Lo, Shang-Lien; Hsieh, Ching-Hong; Chen, Ching-Lung

    2009-04-15

    This study presents the sintering of municipal solid waste incineration (MSWI) fly ash assisted by microwave energy. The composition of fly ash was investigated by chemical sequential extraction and modified microwave digestion method. Effects of process time, container materials, aging time and salt contents were also discussed. The major elements of fly ash are Ca, Cl, Na, Si, K, Al, Mg, and Zn, and the metal species, Zn, Cr, Pb, Ca, and Cu, are mainly in the oxide phase. Under microwave processing, the fly ash was sintered into a glass-ceramics and the leaching concentrations of heavy metals were restrained. The stabilization efficiency increased with an increase in processing time in most of the cases. Better stabilization efficiency of fly ash was discovered by using the SiO(2) or Al(2)O(3) container than by using the graphite plate/SiC plate. The presence of salt in the fly ash could enhance the sintering and stabilization of fly ash. During the aging time of 0-30 days, negligible Pb in the sintered fly ash was leached out, and the leaching concentration was lower than the criterion. PMID:18692957

  19. Optical properties of fly ash. Volume 1, Final report

    Energy Technology Data Exchange (ETDEWEB)

    Self, S.A.

    1994-12-01

    Research performed under this contract was divided into four tasks under the following headings: Task 1, Characterization of fly ash; Task 2, Measurements of the optical constants of slags; Task 3, Calculations of the radiant properties of fly ash dispersions; and Task 4, Measurements of the radiant properties of fly ash dispersions. Tasks 1 and 4 constituted the Ph.D. research topic of Sarbajit Ghosal, while Tasks 2 and 3 constituted the Ph.D. research topic of Jon Ebert. Together their doctoral dissertations give a complete account of the work performed. This final report, issued in two volumes consists of an executive summary of the whole program followed by the dissertation of Ghosal. Volume 1 contains the dissertation of Ghosal which covers the characterization of fly ash and the measurements of the radiant properties of fly ash dispersions. A list of publications and conference presentations resulting from the work is also included.

  20. Synthesis and characterization of fly ash-zinc oxide nanocomposite

    Directory of Open Access Journals (Sweden)

    Kunal Yeole

    2014-04-01

    Full Text Available Fly ash, generated in thermal power plants, is recognized as an environmental pollutant. Thus, measures are required to be undertaken to dispose it in an environmentally friendly method. In this paper an attempt is made to coat zinc oxide nano-particles on the surface of fly ash by a simple and environmentally friendly facile chemical method, at room temperature. Zinc oxide may serve as effective corrosion inhibitor by providing sacrificial protection. Concentration of fly ash was varied as 5, 10 and 15 (w/w % of zinc oxide. It was found that crystallinity increased, whereas particle size, specific gravity and oil absorption value decreased with increased concentration of fly ash in zinc oxide, which is attributed to the uniform distribution of zinc oxide on the surface of fly ash. These nanocomposites can potentially be used in commercial applications as additive for anticorrosion coatings.

  1. Self-healing ability of fly ash-cement systems

    Energy Technology Data Exchange (ETDEWEB)

    Pipat Termkhajornkit; Toyoharu Nawa; Yoichi Yamashiro; Toshiki Saito [Lafarge Research Centre, Quentin Fallavier (France). Reactive Components Department

    2009-03-15

    Concrete is susceptible to cracking due to both autogenous and drying shrinkage. Nevertheless, most of these types of cracks occur before 28 days. Because fly ash continues to hydrate after 28 days, it is likely that hydrated products from fly ash may modify microstructure, seal these cracks, and prolong the service life. This research investigates the self-healing ability of fly ash-cement paste. Compressive strength, porosity, chloride diffusion coefficients, hydration reactions and hydrated products were studied. The research focuses on behavior after 28 days. According to the experimental results, the fly ash-cement system has the self-healing ability for cracks that occur from shrinkage. The self-healing ability increased when the fraction of fly ash increased.

  2. Fly ash used to create alternative building product

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, T.

    1995-04-01

    Autoclaved Cellular Concrete (ACC), a new, concrete-like block containing 70 percent fly ash, is proving to be a superior alternative to concrete, wood and paper products. The ACC block, currently being promoted by the Electric Power Research Institute (EPRI), could reduce both the overall cost of generating electricity from coal and the need for landfill space. The typical fly ash concrete mixture is 4 to 5 percent fly ash. {open_quotes}It doesn`t take a brain surgeon to see that these blocks are a much better outlet for fly ash than the current concrete mixture,{close_quotes} said Dean Golden, EPRI`s project manager. Golden estimates that a typical coal-fired plant can save an average of $10 per ton in landfill costs alone by converting its principal by-product to these blocks. Besides fly ash, the blocks also contain water, cement, lime and aluminum powder.

  3. Use of Recycled Aggregate and Fly Ash in Concrete Pavement

    Directory of Open Access Journals (Sweden)

    Myle N. James

    2011-01-01

    Full Text Available Problem statement: Recycled materials aggregate from the demolished concrete structures and fly ash from burning coal shows the possible application as structural and non structural components in concrete structures. This research aims to evaluate the feasibility of using concrete containing recycled concrete aggregate and fly ash in concrete pavement. Approach: Two water cement ratio (0.45 and 0.55 the compressive strength, modulus of electricity and flexural strength for concrete with recycled aggregate and fly ash with 0, 25% replacing cement in mass were considered. Results: The material properties of recycled aggregate concrete with fly ash indicate comparable results with that of concrete with natural aggregate and without fly ash. Conclusion/Recommendations: The recycled materials could be used in concrete pavement and it will promote the sustainability of concrete.

  4. Electrodialytic removal of Cd from biomass combustion fly ash suspensions.

    Science.gov (United States)

    Kirkelund, Gunvor M; Damoe, Anne J; Ottosen, Lisbeth M

    2013-04-15

    Due to relatively high concentrations of Cd, biomass combustion fly ashes often fail to meet Danish legislative requirements for recycling as fertilizer. In this study, the potential of using electrodialytic remediation for removal of Cd from four different biomass combustion fly ashes was investigated with the aim of enabling reuse of the ashes. The ashes originated from combustion of straw (two ashes), wood chips, and co-firing of wood pellets and fuel oil, respectively. A series of laboratory scale electrodialytic remediation experiments were conducted with each ash. The initial Cd concentration in the ashes varied between 8.8 mg Cd/kg (co-firing ash) and 64 mg Cd/kg (pre-washed straw ash), and pH varied from 3.7 (co-firing ash) to 13.3 (wood ash). In spite of such large variations between the ashes, the electrodialytic method showed to be sufficiently robust to treat the ashes so the final Cd concentration was below 2.0mg Cd/kg DM in at least one experiment done with each ash. This was obtained within 2 weeks of remediation and at liquid to solid (L/S) ratios of L/S 16 for the pre-washed straw ash and L/S 8 for the straw, co-firing and wood ash. PMID:23454460

  5. Removal of colour from effluent of petrochemical industry by fly ash and other agents

    Energy Technology Data Exchange (ETDEWEB)

    Kapadia, M.J.; Farasram, R.P.; Desai, D.H.; Bhatt, M.M. [Gujarat Narmada Valley Fertilizers Co. Ltd., Narmadanagar (India). Central Laboratory

    2001-07-01

    Use of fly ash for removal of colour from the effluent of a petro-chemical industry and optimization of process variables were reported earlier. Further studies in the same direction were conducted on various frontiers to reap the benefit of the process of colour removal by fly ash on a large scale. Among the different particle size fractions of fly ash, an intermittent fraction 150-250 exhibited the highest colour removal efficiency due to high proportion of carbonaceous material and lower proportion of silica. Apart from reduction in colour, treatment of waste water with 5% fly ash also resulted in the reduction of suspended solids, ammoniacal nitrogen, COD, and nitrophenol from effluent with no detrimental effect on effluent chemistry. Keeping the variables constants, the efficiency of fly ash and other adsorbents for reducing colour and COD of effluent was found in the order: powder activated charcoal {gt} carbon soot {gt} granular activated carbon {gt} fly ash. The fly ash could reduce the colour of effluent in batch mode (jar test conditions) as well as continuous mode (passing through filter bed). Restriction of flow rate was encountered in the filter bed system. 15 refs., 2 figs., 7 tabs.

  6. EFFECTS OF FLY ASH ON MERCURY OXIDATION DURING POST COMBUSTION CONDITIONS; ANNUAL

    International Nuclear Information System (INIS)

    the presence of NO appeared to suppress oxidation. The Blacksville fly ash tended to show slightly more catalytic activity than the PRB fly ash, but this could be largely due to the higher surface area of the Blacksville ash. Temperature was not a statistically important factor. The magnetic (Fe-rich) phases did not appear to be more catalytically active than the nonmagnetic phases, and unburned carbon did not appear to play a critical role in oxidation chemistry

  7. Effect of Tartaric Acid on Hydration of a Sodium-Metasilicate-Activated Blend of Calcium Aluminate Cement and Fly Ash F

    Directory of Open Access Journals (Sweden)

    Tatiana Pyatina

    2016-05-01

    Full Text Available An alkali-activated blend of aluminum cement and class F fly ash is an attractive solution for geothermal wells where cement is exposed to significant thermal shocks and aggressive environments. Set-control additives enable the safe cement placement in a well but may compromise its mechanical properties. This work evaluates the effect of a tartaric-acid set retarder on phase composition, microstructure, and strength development of a sodium-metasilicate-activated calcium aluminate/fly ash class F blend after curing at 85 °C, 200 °C or 300 °C. The hardened materials were characterized with X-ray diffraction, thermogravimetric analysis, X-ray computed tomography, and combined scanning electron microscopy/energy-dispersive X-ray spectroscopy and tested for mechanical strength. With increasing temperature, a higher number of phase transitions in non-retarded specimens was found as a result of fast cement hydration. The differences in the phase compositions were also attributed to tartaric acid interactions with metal ions released by the blend in retarded samples. The retarded samples showed higher total porosity but reduced percentage of large pores (above 500 µm and greater compressive strength after 300 °C curing. Mechanical properties of the set cements were not compromised by the retarder.

  8. Vitrification of municipal solid waste incineration fly ash using biomass ash as additives.

    Science.gov (United States)

    Alhadj-Mallah, Moussa-Mallaye; Huang, Qunxing; Cai, Xu; Chi, Yong; Yan, JianHua

    2015-01-01

    Thermal melting is an energy-costing solution for stabilizing toxic fly ash discharged from the air pollution control system in the municipal solid waste incineration (MSWI) plant. In this paper, two different types of biomass ashes are used as additives to co-melt with the MSWI fly ash for reducing the melting temperature and energy cost. The effects of biomass ashes on the MSWI fly ash melting characteristics are investigated. A new mathematical model has been proposed to estimate the melting heat reduction based on the mass ratios of major ash components and measured melting temperature. Experimental and calculation results show that the melting temperatures for samples mixed with biomass ash are lower than those of the original MSWI fly ash and when the mass ratio of wood ash reaches 50%, the deformation temperature (DT), the softening, hemisphere temperature (HT) and fluid temperature (FT) are, respectively, reduced by 189°C, 207°C, 229°C, and 247°C. The melting heat of mixed ash samples ranges between 1650 and 2650 kJ/kg. When 50% wood ash is mixed, the melting heat is reduced by more than 700 kJ/kg for the samples studied in this paper. Therefore, for the vitrification treatment of the fly ash from MSW or other waste incineration plants, wood ash is a potential fluxing assistant.

  9. Fly ash in landfill top covers - a review.

    Science.gov (United States)

    Brännvall, E; Kumpiene, J

    2016-01-01

    Increase of energy recovery from municipal solid waste by incineration results in the increased amounts of incineration residues, such as fly ash, that have to be taken care of. Material properties should define whether fly ash is a waste or a viable resource to be used for various applications. Here, two areas of potential fly ash application are reviewed: the use of fly ash in a landfill top cover either as a liner material or as a soil amendment in vegetation layer. Fly ashes from incineration of three types of fuel are considered: refuse derived fuel (RDF), municipal solid waste incineration (MSWI) and biofuel. Based on the observations, RDF and MSWI fly ash is considered as suitable materials to be used in a landfill top cover liner. Whereas MSWI and biofuel fly ashes based on element availability for plant studies, could be considered suitable for the vegetation layer of the top cover. Responsible application of MSWI ashes is, however, warranted in order to avoid element accumulation in soil and elevation of background values over time. PMID:26701627

  10. Assessing fly ash treatment: Remediation and stabilization of heavy metals

    KAUST Repository

    Lima, A.T.

    2010-12-17

    Fly ashes from Municipal Solid Waste (MSW), straw (ST) and co-combustion of wood (CW) are here analyzed with the intent of reusing them. Two techniques are assessed, a remediation technique and a solidification/stabilization one. The removal of heavy metals from fly ashes through the electrodialytic process (EDR) has been tried out before. The goal of removing heavy metals has always been the reuse of fly ash, for instance in agricultural fields (BEK). The best removal rates are here summarized and some new results have been added. MSW fly ashes are still too hazardous after treatment to even consider application to the soil. ST ash is the only residue that gets concentrations low enough to be reused, but its fertilizing value might be questioned. An alternative reuse for the three ashes is here preliminary tested, the combination of fly ash with mortar. Fly ashes have been substituted by cement fraction or aggregate fraction. Surprisingly, better compressive strengths were obtained by replacing the aggregate fraction. CW ashes presented promising results for the substitution of aggregate in mortar and possibly in concrete. © 2010 Elsevier Ltd.

  11. Natural radioactivity of coal and fly ash at the Nikola Tesla B TPP

    Directory of Open Access Journals (Sweden)

    Kisić Dragica M.

    2013-01-01

    Full Text Available Serbian thermal power plants (TPPs produce siliceous fly ash from lignite in the quantity of approximately 6 million tons per year. The potential market for the use of fly ash is operational, but for the time being, only used by cement producers. Fly ash radioactivity could be one of the major points of concern when larger use of fly ash is planned, particularly in the Serbian construction industry. Radioactivity measurements have been conducted regularly for decades. This paper presents the results of a ten-year fly ash radioactivity measurements at the Nikola Tesla B TPP located in Obrenovac. In addition, the paper compares the natural radionuclides coal content data combusted by the Nikola Tesla B TPP boilers coming from the Kolubara Basin and ash created during coal combustion. Fly ash created in the Nikola Tesla TPPs boilers is characterised by the increased concentration of the natural radionuclides content compared to coal. This is the so-called technologically enhanced natural radioactivity (Technologically Enhanced Occurring Radioactive Material - TENORM of industrial waste, whereas the average specific activities: 232Th in coal amount to 25.2 Bq/kg, and in fly ash and coal 84.2 Bq/kg and 238U 38.3 Bq/kg, respectively. Following the obtained natural radionuclides content results it may be concluded that the Nikola Tesla B TPP ash may be disposed into the environment. Ash may be used also in the construction industry (civil engineering. In building construction applications, ash share as the additive to other building materials depends from its physical and chemical characteristics, as well as from the radionuclides activity: 266Ra, 232Th and 40K. Unlike the thermal power plants regularly (once a year testing the specific natural radionuclides activity in the combusted coal and boiler fly ash, Electric Power Industry of Serbia has not performed large-scale investigations of the natural radionuclides content in coal within the Kolubara

  12. Zeolite from fly ash: synthesis and characterization

    Indian Academy of Sciences (India)

    Keka Ojha; Narayan C Pradhan; Amar Nath Samanta

    2004-12-01

    Coal fly ash was used to synthesize X-type zeolite by alkali fusion followed by hydrothermal treatment. The synthesized zeolite was characterized using various techniques such as X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, BET method for surface area measurement etc. The synthesis conditions were optimized to obtain highly crystalline zeolite with maximum BET surface area. The maximum surface area of the product was found to be 383 m2/g with high purity. The crystallinity of the prepared zeolite was found to change with fusion temperature and a maximum value was obtained at 823 K. The cost of synthesized zeolite was estimated to be almost one-fifth of that of commercial 13X zeolite available in the market.

  13. Application of Fly Ash from Solid Fuel Combustion in Concrete

    DEFF Research Database (Denmark)

    Pedersen, Kim Hougaard

    2008-01-01

    Nordjyllandsværket, unit 3; 3) post treatment of fly ash to lower its AEA adsorptivity. The foam index test is the method usually employed to determine the degree of fly ash interference with AEAs in concrete. The test involves the use of commercial AEAs and visual observation of foam stability. These facts reduce...... with implementation of low-NOx combustion technologies. The present thesis concerns three areas of importance within this field: 1) testing of fly ash adsorption behavior; 2) the influence of fuel type and combustion conditions on the ash adsorption behaviour including full-scale experiments at the power plant...... has a low sensitivity toward small variations in AEA adsorption between different fly ashes and it requires further work before a finished procedure is accomplished. Finally, it was shown that changes in temperature affect both test methods. Pulverized fuel has been combusted in an entrained flow...

  14. Leaching of nutrient salts from fly ash from biomass combustion

    DEFF Research Database (Denmark)

    Thomsen, Kaj; Vu, Duc Thuong; Stenby, Mette;

    2005-01-01

    Methods to selectively leach nutrient salts from fly ash, while leaving cadmium un-dissolved were studied. Temperature, pH, water to fly ash ratio are all expected to influence the kinetics and the equilibrium boundaries for this process. Three different leaching methods were investigated. The...... moving bed process with agitation/centrifugation. It was found that a satisfactory leaching of the nutrient salts could be achieved with the third method using only two or three stages, depending on the water to fly ash ratio. It is an advantage to perform the process at temperatures above 50°C as the...... first method was a counter current moving bed process in four stages. The ash was kept in filter bags and leached with water that was introduced into the bags at 40-50°C. In the second method, fly ash and water was brought into contact in a partially fluidized bed. The third method was a counter current...

  15. Creep Behaviour of Fly Ash-Based Geopolymer Concrete

    Directory of Open Access Journals (Sweden)

    Wallah S.E.

    2010-01-01

    Full Text Available Fly ash-based geopolymer concrete is manufactured using fly ash as its source material and does not use Portland cement at all. Beside fly ash, alkaline solution is also utilized to make geopolymer paste which binds the aggregates to form geopolymer concrete. This paper presents the study of creep behaviour of fly ash-based geopolymer concrete. Four series of specimens with various compressive strengths were prepared to study its creep behaviour for the duration of test up to one year. The test method followed the procedures applied for Ordinary Portland Cement (OPC concrete. Test results show that fly ash-based geopolymer concrete undergoes low creep which is generally less than that of OPC concrete. After one year of loading, the results for specific creep of fly ash-based geopolymer concrete in this study ranges from 15 to 29 microstrain for concrete compressive strength 67–40 MPa respectively. From the test results, it is also found out that the creep coefficient of fly ash-based geopolymer concrete is about half of that predicted using Gilbert’s Method for OPC concrete.

  16. Stabilization of Expansive Soil by Lime and Fly Ash

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ji-ru; CAO Xing

    2002-01-01

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

  17. Coal fly ash: a retrospective and future look

    Energy Technology Data Exchange (ETDEWEB)

    Manz, O.E. [University of North Dakota, Grand Forks, ND (United States). Civil Engineering Dept.

    1998-07-01

    In 1996, approximately 7.28 million metric tons (8.02 million short tons) of coal fly ash was used in the United States in cement and concrete products. The amount of fly ash in typical structural concrete applications ranges from 15 to 35% by weight, with amounts up to 70% for mass concrete in dams, walls, and girders and for roller-compacted concrete pavements and parking areas. Various concrete mixtures are produced with coal fly ash, including regular weight and lightweight concretes, high-strength concrete, low-slump paving concrete, and architectural concrete. With the principal exception of high-strength concrete, these mixtures are routinely air-entrained for added workability and for resistance to freezing and thawing. A state-of-the-art report on the use of coal fly ash in concrete has been prepared by the American Concrete Institute (ACI): Use of Fly Ash in Concrete, ACI 232.2R-96. Fly ash for use as a mineral admixture in concrete is covered in a specification published by the American Society for Testing and Materials (ASTM): Mineral Admixture in Portland Cement Concrete, ASTM C618. Revisions to the Canadian Standard CSA A 23.5 are also discussed, together with barriers to the use of fly ash. 2 photos.

  18. Carbonatation Influence on Fly Ash and Portland Cement Mortars

    Directory of Open Access Journals (Sweden)

    P.L. Valdez–Tamez

    2009-01-01

    Full Text Available The influence of carbonation on mortars containing 25% of fly ash instead of the cementitious materials was studied. Mortar cylinder specimens were fabricated for 4 different W/C ratios: 0.35, 0.45, 0.55 and 0.65. Mortars with and without fly ash were subjected to an accelerated carbonation process. Volumetric weight, water absorption, compressive strength, water permeability, pH and mercury intrusion porosimetry of the mortar specimens were determined. Due to the fly ash pozzolanic potential, for all W/C ratios, results of the compressive strength tests at 28 days of the mortars with and without fly ash were similar. Mortars with fly ash presented similar water permeability as mortars without fly ash. PH results showed that alkalinity reduction is lower in mortars with fly ash compared to those containing cement only. In all the mortars, the porosimetric analysis indicated that porosity is reduced due to carbonation. Further more, it is showed the predominance of the macro and mesopores.

  19. The use of neutron activation analysis for the study of environmental risks associated with the fly ash from burning Polish coals

    International Nuclear Information System (INIS)

    An INAA procedure for the determination of twelve elements in fly ash and in similar geological materials was developed using mixed elemental standards and iron wire as neutron flux monitors. The reliability of the method was checked using the IAEA's Soil-5 and Lake Sediment SL-1 CRMs. The results obtained for the fly ash from burning Polish hard coal, as well as for two other geological materials, are presented. A new candidate reference material: fine fly ash (CTA-FFA-1) was collected, characterized with respect to its major component contents, homogenized, and distributed into PE containers. In order to certify the material with respect to its trace element contents, an international intercomparison run was organized. Preliminary experiments on leaching of trace elements from neutron-irradiated fly ash were performed. Some distinct differences in the leaching characteristics of individual elements were noted. In future the work will concentrate on extending the multielement capability of the INAA method, as well as on leaching of trace elements by solutions simulating acid rain. The work on certification of the new CRM, fine fly ash, CTA-FFA-1, will be continued. 28 refs, 9 figs, 4 tabs

  20. Investigation on Leaching Behaviour of Fly Ash and Bottom Ash Replacement in Self-Compacting Concrete

    Science.gov (United States)

    Kadir, Aeslina Abdul; Ikhmal Haqeem Hassan, Mohd; Bakri Abdullah, Mohd Mustafa Al

    2016-06-01

    Fly ash and bottom ash are some of the waste generated by coal-fired power plants, which contains large quantities of toxic and heavy metals. In recent years, many researchers have been interested in studying on the properties of self-compacting concrete incorporated with fly ash and bottom ash but there was very limited research from the combination of fly ash and bottom ash towards the environmental needs. Therefore, this research was focused on investigating the leachability of heavy metals of SCC incorporated with fly ash and bottom ash by using Toxicity Characteristic Leaching Procedure, Synthetic Precipitation Leaching Procedure and Static Leaching Test. The samples obtained from the coal-fired power plant located at Peninsula, Malaysia. In this study, the potential heavy metals leached out from SCC that is produced with fly ash as a replacement for Ordinary Portland Cement and bottom ash as a substitute for sand with the ratios from 10% to 30% respectively were designated and cast. There are eight heavy metals of concern such as As, Cr, Pb, Zn, Cu, Ni, Mn and Fe. The results indicated that most of the heavy metals leached below the permissible limits from the United States Environmental Protection Agency and World Health Organization limit for drinking water. As a conclusion, the minimum leaching of the heavy metals from the incorporation of fly ash and bottom ash in self-compacting concrete was found in 20% of fly ash and 20% of bottom ash replacement. The results also indicate that this incorporation could minimize the potential of environmental problems.

  1. Behaviour of Onobrychis Viciifolia Growing on Fly Ash Experimental Parcels

    OpenAIRE

    Florica Morariu; Smaranda Mâsu; Dumitru Popescu

    2011-01-01

    Studies were conducted to identify a treatment method for upper layers of fly ash to cover them with vegetation. Fixing plant layer acts against erosion/washes of fly ash deposits. Studies emphasized the need of use of an organic fertilizer mixed with inorganic materials such as volcanic tuff and, also, the need of selecting a plant species compatible with the treated culture medium. The use of an amended variant of compost and modified volcanic tuff of fly ash layers shows that the selected ...

  2. Synthesis of high ion exchange zeolites from coal fly ash

    OpenAIRE

    Ayora, Carlos; Querol, Xavier; Moreno, N.; Alastuey, Andrés; Juan Mainar, Roberto; Andrés Gimeno, José Manuel; López Soler, Ángel; Medinaceli, Alejandro; Valero, Antonio

    2007-01-01

    This study focuses on the synthesis at a pilot plant scale of zeolitic material obtained from the coal fly ashes of the Teruel and Narcea power plants in Spain. After the optimisation of the synthesis parameters at laboratory scale, the Teruel and Narcea fly ashes were selected as low and high glass fly ashes. The pilot plant scale experiments were carried out in a 10 m3 reactor of Clariant SA (Barcelona, Spain). The results allowed obtaining 1.1 and 2.2 tonnes of zeolitic material with 40 an...

  3. Carbonatation Influence on Fly Ash and Portland Cement Mortars

    OpenAIRE

    P.L. Valdez–Tamez; A. Durán–Herrera; G. Fajardo–San Miguel; C.A. Juárez–Alvarado

    2009-01-01

    The influence of carbonation on mortars containing 25% of fly ash instead of the cementitious materials was studied. Mortar cylinder specimens were fabricated for 4 different W/C ratios: 0.35, 0.45, 0.55 and 0.65. Mortars with and without fly ash were subjected to an accelerated carbonation process. Volumetric weight, water absorption, compressive strength, water permeability, pH and mercury intrusion porosimetry of the mortar specimens were determined. Due to the fly ash pozzolanic potential...

  4. Usage of fly ash as a coal desulphurization reagent

    Energy Technology Data Exchange (ETDEWEB)

    Yaman, S.; Kuecuekbayrak, S. [Istanbul Technical Univ. (Turkey). Chemical and Metallurgical Engineering Faculty

    1996-12-31

    This paper covers the direct usage of fly ash to remove sulphur from coal. Experiments were carried out on a high sulphur Turkish lignite. 5 g of fly ash was extracted in 200 ml of water under pressure and the dilute solution containing water extractable parts of fly ash was used as desulphurization reagent. Oxygen pressure was created over desulphurization medium during the extraction period by which dissolved oxygen was concentrated in the solution. Effects of temperature, partial pressure of oxygen, and time were investigated in the ranges of 403--498 K, 0.0--1.5 MPa and 15--90 min, respectively.

  5. CHARACTERIZATION AND COMPARISON OF TREATED AND UNTREATED RICH HUSH ASH & FLY ASH FOR METAL MATRIX COMPOSITES

    Directory of Open Access Journals (Sweden)

    Ravinder Pal Singh

    2011-10-01

    Full Text Available Rice Husk ash and fly ash are agricultural and coal wastes respectively. These are produced in abundance globally and poses risk to health as well as environment. Thus their effective, conducive and eco-friendly utilization has always been a challenge for scientific community. The fly ash has been used as reinforcement for improved mechanical properties of composites (1,3-5,9. Rice husk ash can also be used for similar applications as its composition is almost similar to that of fly ash. This paper mainly deals with identification ofcharacteristics of both the fly ash and rice husk ash using spectroscopic and microscopic analysis. SEM, XRD,XRF and FTIR spectroscopic methods were used for the characterization of treated and untreated ashes. The results were compared and it was observed that both ashes possesses nearly same chemical phases and otherfunctional groups thus proposing the use of rice husk ash as reinforcement like fly ash in Metal Matrix Composites (MMCs specifically for wear resistance applications.

  6. Hydration of Hybrid Alkaline Cement Containing a Very Large Proportion of Fly Ash: A Descriptive Model

    Directory of Open Access Journals (Sweden)

    Inés Garcia-Lodeiro

    2016-07-01

    Full Text Available In hybrid alkaline fly ash cements, a new generation of binders, hydration, is characterized by features found in both ordinary portland cement (OPC hydration and the alkali activation of fly ash (AAFA. Hybrid alkaline fly ash cements typically have a high fly ash (70 wt % to 80 wt % and low clinker (20 wt % to 30 wt % content. The clinker component favors curing at ambient temperature. A hydration mechanism is proposed based on the authors’ research on these hybrid binders over the last five years. The mechanisms for OPC hydration and FA alkaline activation are summarized by way of reference. In hybrid systems, fly ash activity is visible at very early ages, when two types of gel are formed: C–S–H from the OPC and N–A–S–H from the fly ash. In their mutual presence, these gels tend to evolve, respectively, into C–A–S–H and (N,C–A–S–H. The use of activators with different degrees of alkalinity has a direct impact on reaction kinetics but does not modify the main final products, a mixture of C–A–S–H and (N,C–A–S–H gels. The proportion of each gel in the mix does, however, depend on the alkalinity generated in the medium.

  7. Effective use of fly ash slurry as fill material.

    Science.gov (United States)

    Horiuchi, S; Kawaguchi, M; Yasuhara, K

    2000-09-15

    A lot of effort has been put into increasing coal ash utilization; however, 50% of total amount is disposed of on land and in the sea. Several attempts have been reported recently concerning slurried coal fly ash use for civil engineering materials, such as for structural fill and backfill. The authors have studied this issue for more than 15 years and reported its potential for (1) underwater fills, (2) light weight backfills, and (3) light weight structural fills, through both laboratory tests and construction works. This paper is an overview of the results obtained for slurry, focusing on the following. (1) Coal fly ash reclaimed by slurry placement shows lower compressibility, higher ground density, and higher strength than by the other methods. This higher strength increases stability against liquefaction during earthquake. (2) Higher stability of the fly ash ground formed by slurry placement is caused by higher density and its self-hardening property. (3) Stability of fly ash reclaimed ground can be increased by increasing density and also by strength enhancement by cement addition. (4) Technical data obtained through a man-made island construction project shows the advantages of fly ash slurry in terms of mechanical properties such as higher stability against sliding failure, sufficient ground strength, and also in terms of cost saving. (5) Concentration in leachates from the placed slurry is lower than the Japanese environmental law. (6) In order to enlarge the fly ash slurry application toward a lightweight fill, mixtures of air foam, cement and fly ash were examined. Test results shows sufficient durability of this material against creep failure. This material was then used as lightweight structural fill around a high-rise building, and showed sufficient quality. From the above data, it can be concluded that coal fly ash slurry can be effectively utilized in civil engineering projects.

  8. Effect of fly ash calcination in geopolymer synthesis

    Science.gov (United States)

    Samadhi, Tjokorde Walmiki; Jatiningrum, Mirna; Arisiani, Gresia

    2015-12-01

    Geopolymer, a largely amorphous class of inorganic polymer consisting of aluminosilicate repeat units, is an environmentally attractive engineering material due to its ability to consume aluminosilicate waste as raw materials. This work studies the effect of the calcination temperature of a coal fly ash generated by a low-efficiency boiler on the mechanical strength of geopolymer mortar synthesized using a mixture of the fly ash, potassium hydroxide as the alkali activator, and locally available sand as the filler aggregate. The calcination temperature is varied between 500-700 °C, with a calcination period of 2 hours in an electric furnace. Two sand samples with different particle size distributions are used. The key response variable is the compressive strength at room temperature, measured after curing at 80 °C for 7 and 14 days. Uncalcined ash, with a carbon content of approximately 31.0%, is not amenable for geopolymer synthesis. Analysis of experimental data using the ANOVA method for general factorial design identifies significant main effects for all three experimental variables. Two-way interactions are significant, except that between sand type and curing period. Higher calcination temperature significantly improves the strength of the mortar. However, the strength of the obtained geopolymer mortars are still significantly lower than that of ordinary Portland cement mortar.

  9. Radon exhalation rates of concrete modified with fly ash and silica fumes

    International Nuclear Information System (INIS)

    The radiological impact of the environmental gas radon to the health of general public is of concern since many decades. Cement used for the construction blended with fly ash and silica fumes is recommended by Government in order to avoid the soil and environmental pollution. But these addition step-up the Indoor radon level in the dwelling due to radioactivity contents. The exhalation of radon from concrete blended with silica fumes and fly ash depends upon addition level, porosity, moisture and radioactivity content. In order to optimize the level of substitution of silica fumes and fly ash, measurements of radon exhalation rates from the concrete blended with different proportions of fly ash and silica fumes was carried out using active scintillation radon monitor. The effect of porosity, moisture, back diffusion and radioactivity content of the concrete on exhalation rates is studied. The measured exhalation rates were extrapolated for indoor radon concentration and effective dose equivalent using ICRP, 1987 recommendations. (author)

  10. Improved Sorting Scheme of Microstructure of Fly Ash

    Institute of Scientific and Technical Information of China (English)

    王立刚; 彭苏平

    2002-01-01

    Aiming at the problem of the existing sorting for microstructure of flyash, an improved scheme was put forward in this paper. First, fly ash particles are divided into four groups as low-calcium, iron, high calcium and char particle acco rding to the substance components of fly ash. Then fly ash particles are divided into 14 sub-groups, for example: cenospheres, plerospheres, solid spheres, porous char and dense char based on their chemical composition, shape and the chara cteristics of inner-structure of fly ash. It has a distinct difference in granu le configuration, inner-structure and substance components. Some disadvantages of the existing scheme such as unilateralism and imprecision have been overcome in the advanced schemes.

  11. Fly-ash lobby design to convert the sceptics

    Energy Technology Data Exchange (ETDEWEB)

    Bile, P.

    1983-07-14

    New uses for pfa in structural concrete have been pioneered at Didcot power station. Twenty percent cost savings and significant gains in long-term strength are claimed for the new concrete, called high fly-ash content concrete (HFCC).

  12. Fly ash based zeolitic pigments for application in anticorrosive paints

    Science.gov (United States)

    Shaw, Ruchi; Tiwari, Sangeeta

    2016-04-01

    The purpose of this work is to evaluate the utilization of waste fly ash in anticorrosive paints. Zeolite NaY was synthesized from waste fly ash and subsequently modified by exchanging its nominal cation Na+ with Mg2+ and Ca2+ ions. The metal ion exchanged zeolite was then used as anticorrosive zeolitic pigments in paints. The prepared zeolite NaY was characterized using X-Ray diffraction technique and Scanning electron microscopy. The size, shape and density of the prepared fly ash based pigments were determined by various techniques. The paints were prepared by using fly ash based zeolitic pigments in epoxy resin and the percentages of pigments used in paints were 2% and 5%. These paints were applied to the mild steel panels and the anticorrosive properties of the pigments were assessed by the electrochemical spectroscopy technique (EIS).

  13. Electrodialytic removal of cadmium from straw combustion fly ash

    DEFF Research Database (Denmark)

    Hansen, Henrik K.; Ottosen, Lisbeth M.; Villumsen, Arne

    2004-01-01

    Fly ash from straw combustion contains valuable nutrients when returned to agricultural soils. In many instances, however, this fly ash may contain heavy metals, such as cadmium, at levels which often exceed the limits given by the Danish legislation. Thus before utilizing the nutrients, cadmium...... must be removed from these ashes. The use of an electrodialytic remediation method to remove cadmium from fly ash arising from straw combustion and containing 11.2 mg Cd kg$+-1$/ DM (dry matter) was accessed. After 36 days of remediation at a constant current density of 5.6 mA cm$+-2$/ more than 97......% of the cadmium had been removed from around 150 g ash on a dry basis. $CPY 2004 Society of Chemical Industry....

  14. Influences of Fly Ash on Concrete Product's Properties and Environmental Impact Reduction

    OpenAIRE

    Thipsuree Kornboonraksa; Thirdpong Srisukphun

    2015-01-01

    This research aimed to study effects of incorporating fly ash into concrete products. Scope of this study were (1) hazard identification of fly ash (2) study on standard testing of various concrete products and (3) study on environmental impact assessment of concrete products mixed with fly ash. Various types of fly ash namely A, B, C and D were sampling from different power plants. Hazard identification of fly ash was analyzed in terms of total threshold limit concentration (TTLC) and solubl...

  15. Use of Recycled Aggregate and Fly Ash in Concrete Pavement

    OpenAIRE

    Myle N. James; Wonchang Choi; Taher Abu-Lebdeh

    2011-01-01

    Problem statement: Recycled materials aggregate from the demolished concrete structures and fly ash from burning coal shows the possible application as structural and non structural components in concrete structures. This research aims to evaluate the feasibility of using concrete containing recycled concrete aggregate and fly ash in concrete pavement. Approach: Two water cement ratio (0.45 and 0.55) the compressive strength, modulus of electricity and flexural streng...

  16. KINETICS OF FLY ASH BENEFICIATION BY CARBON BURNOUT

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Joseph N.D. Dodoo; Dr. Joseph M. Okoh

    2000-11-01

    Surface area analyses performed on fly ash samples reveal that the surface area is controlled by carbon content. The higher surface areas found in large particles are due to the presence of highly porous carbonaceous particles. Adsorption-desorption isotherms and t-plots of fly ash samples indicate that fly ash is porous. BJH Adsorption/Desorption pore size analysis reveal that pore diameters are independent of sieve size. They appear to be dependent only on the nature of the material which confers porosity. Based on the results of Brown and Dykstra (41) it is reasonable to assume that calculations of reaction rates at temperatures above 550 C were confounded by weight losses from processes other than carbon oxidation and, therefore, are not useful in determination of the temperature dependence of carbon oxidation in fly ash. The results of the present study indicate that temperatures below 550 C should be used for future studies in order to satisfactorily assess the temperature dependence of carbon oxidation in fly ash. Furthermore, it is also advisable that percent carbon determinations be performed on fly ash samples after the oxidation reactions to determine whether all carbon present in fly ash is oxidized. This will ensure that reaction rates are representative of the complete oxidation of carbon. An inverse relationship was determined between reaction rates and oxygen concentration for this study. As discussed, this may be due to volatilization of volatiles from fly ash and ease of transport of products away from the reaction sites by the action of the vacuum applied to the samples. A more accurate determination of oxygen dependence of carbon oxidation can be accomplished by the use of specialty gases containing different concentrations of oxygen which could eliminate the need to apply vacuum to the samples.

  17. Hydraulic transportation of fly ash: a laboratory-scale investigation

    Energy Technology Data Exchange (ETDEWEB)

    Jain, M.K.; Sastry, B.S. [Anna University, Chennai (India). Dept. of Mining Engineering

    2006-07-01

    Flow behaviour of fly ash slurry is a very complex phenomenon. The present study tries to examine the relation between flow rate and pressure loss of fly ash slurry under laboratory-scale experiment set up in the light of available theoretical background. Pressure loss increases with the increase in flow rate and solid concentration but pressure losses can be saved by the addition of 2200 PPM (parts per million) concentration of polyacrylamide polymer. 6 refs., 7 figs., 4 tabs.

  18. Elemental content of aquatic organisms inhabiting a pond contaminated with coal fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Furr, A.K.

    1979-01-01

    Using neutron activation and other methods, 39 elements were determined in algae, aquatic weeds, dragon fly nymphs, newts, fish and muskrats from a pond contaminated by coal fly ash. The organisms contained several elements, including selenium, at concentrations markedly higher than those in controls.

  19. Mutagenicity and genotoxicity of coal fly ash water leachate

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, R.; Mukherjee, A. [University of Calcutta, Calcutta (India). Dept. of Botany

    2009-03-15

    Fly ash is a by-product of coal-fired electricity generation plants. The prevalent practice of disposal is as slurry of ash and water to storage or ash ponds located near power stations. This has lain to waste thousands of hectares of land all over the world. Since leaching is often the cause of off-site contamination and pathway of introduction into the human environment, a study on the genotoxic effects of fly ash leachate is essential. Leachate prepared from the fly ash sample was analyzed for metal content, and tested for mutagenicity and genotoxicity. Analyses of metals show predominance of the metals - sodium, silicon, potassium, calcium, magnesium, iron, manganese, zinc, and sulphate. The Ames Salmonella mutagenicity assay, a short-term bacterial reverse mutation assay, was conducted on two-tester strains of Salmonella typhimurium strains TA97a and TA102. For genotoxicity, the alkaline version of comet assay on fly ash leachate was carried in vitro on human blood cells and in vivo on Nicotiana plants. The leachate was directly mutagenic and induced significantconcentration-dependent increases in DNA damage in whole blood cells, lymphocytes, and in Nicotiana plants. The comet parameters show increases in tail DNA percentage (%), tail length (mu m), and olive tail moment (arbitrary units). Our results indicate that leachate from fly ash dumpsites has the genotoxic potential and may lead to adverse effects on vegetation and on the health of exposed human populations.

  20. Damping properties of fly ash/epoxy composites

    Institute of Scientific and Technical Information of China (English)

    Jian Gu; Gaohui Wu; Xiao Zhao

    2008-01-01

    An inexpensive fly ash (FA), which is from a waste product, was employed to prepare fly ash/epoxy composites. The purpose of this study is to characterize the contributions of matrix viscoelasticity, hollow structure characteristic (porosity), and filler/matrix interface friction to the high vibration damping capacity of such composites. The damping properties of the composites were investigated in the temperature range of-40 to 150℃C and in the frequency range of 10 to 800 Hz by using a tension-compression mode. The results indicate that the peak value of damping loss factor (tanδ) for the fly ash/epoxy composites can reach 0.70-0.90 in test specification, and the attenuation of damping loss factor is inconspicuous with increasing frequency. In addition, scanning electron microscope (SEM) was used to observe the morphology of the fly ash as well as its distribution in the matrix, which will help to analyze the effect of fly ash on the damping properties of the fly ash/epoxy composites.

  1. Development of fly ash-based automotive brake lining

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, S.; Chugh, Y.P. [South Illinois University, Carbondale, IL (United States). College of Engineering

    2007-07-15

    Coal-fired power plants all over the world generate huge amounts of fly ash each year, 70 million tons of which are produced in the United States alone. Only 40% of all fly ashes generated in the USA find beneficial applications and rest have to be disposed off, which is burden for the generation industry. Fly ash particles possess certain characteristics that make them suitable for use in friction composites as a filter material. An attempt has been made through this research to incorporate more than 50wt% of fly ash particles in automotive brake lining friction composites. This paper presents the research carried out on development of friction composites, using fly ash obtained from a specific power plant in Illinois. Ingredients such as phenolic resin, aramid pulp, glass fiber, potassium titanate, graphite, aluminum fiber and copper powder were used in the composite development phase, in addition to the fly ash. The developed brake lining composites have exhibited consistent coefficients of friction in the range of 0.35-0.4, and wear rates lower than 12wt%.

  2. Recyclability of Concrete Pavement Incorporating High Volume of Fly Ash

    Directory of Open Access Journals (Sweden)

    Isamu Yoshitake

    2015-08-01

    Full Text Available Recyclable concrete pavement was made from fly ash and crushed limestone sand and gravel as aggregates so that the concrete pavement could be recycled to raw materials for cement production. With the aim to use as much fly ash as possible for the sustainable development of society, while achieving adequate strength development, pavement concrete having a cement-replacement ratio of 40% by mass was experimentally investigated, focusing on the strength development at an early age. Limestone powder was added to improve the early strength; flexural strength at two days reached 3.5 MPa, the minimum strength for traffic service in Japan. The matured fly ash concrete made with a cement content of 200 kg/m3 achieved a flexural strength almost equal to that of the control concrete without fly ash. Additionally, Portland cement made from the tested fly ash concrete was tested to confirm recyclability, with the cement quality meeting the Japanese classification of ordinary Portland cement. Limestone-based recyclable fly ash concrete pavement is, thus, a preferred material in terms of sustainability.

  3. [Study on mercury re-emissions during fly ash utilization].

    Science.gov (United States)

    Meng, Yang; Wang, Shu-Xiao

    2012-09-01

    The amount of fly ash produced during coal combustion is around 400 million tons per year in China. About 65%-68% of fly ash is used in building material production, road construction, architecture and agriculture. Some of these utilization processes include high temperature procedures, which may lead to mercury re-emissions. In this study, experiments were designed to simulate the key process in cement production and steam-cured brick production. A temperature programmed desorption (TPD) method was used to study the mercury transformation in the major utilization processes. Mercury re-emission during the fly ash utilization in China was estimated based on the experimental results. It was found that mercury existed as HgCl2 (Hg2 Cl2), HgS and HgO in the fly ash. During the cement production process, more than 98% of the mercury in fly ash was re-emitted. In the steam-curing brick manufacturing process, the average mercury re-emission percentage was about 28%, which was dominated by the percentage of HgCl2 (Hg2 Cl2). It is estimated that the mercury re-emission during the fly ash utilization have increased from 4.07 t in 2002 to 9.18 t in 2008, of which cement industry contributes about 96.6%. PMID:23243850

  4. Properties and Leachability of Self-Compacting Concrete Incorporated with Fly Ash and Bottom Ash

    Science.gov (United States)

    Kadir, Aeslina Abdul; Ikhmal Haqeem Hassan, Mohd; Jamaluddin, Norwati; Bakri Abdullah, Mohd Mustafa Al

    2016-06-01

    The process of combustion in coal-fired power plant generates ashes, namely fly ash and bottom ash. Besides, coal ash produced from coal combustion contains heavy metals within their compositions. These metals are toxic to the environment as well as to human health. Fortunately, treatment methods are available for these ashes, and the use of fly ash and bottom ash in the concrete mix is one of the few. Therefore, an experimental program was carried out to study the properties and determine the leachability of selfcompacting concrete incorporated with fly ash and bottom ash. For experimental study, self-compacting concrete was produced with fly ash as a replacement for Ordinary Portland Cement and bottom ash as a replacement for sand with the ratios of 10%, 20%, and 30% respectively. The fresh properties tests conducted were slump flow, t500, sieve segregation and J-ring. Meanwhile for the hardened properties, density, compressive strength and water absorption test were performed. The samples were then crushed to be extracted using Toxicity Characteristic Leaching Procedure and heavy metals content within the samples were identified accordingly using Atomic Absorption Spectrometry. The results demonstrated that both fresh and hardened properties were qualified to categorize as self-compacting concrete. Improvements in compressive strength were observed, and densities for all the samples were identified as a normal weight concrete with ranges between 2000 kg/m3 to 2600 kg/m3. Other than that, it was found that incorporation up to 30% of the ashes was safe as the leached heavy metals concentration did not exceed the regulatory levels, except for arsenic. In conclusion, this study will serve as a reference which suggests that fly ash and bottom ash are widely applicable in concrete technology, and its incorporation in self-compacting concrete constitutes a potential means of adding value to appropriate mix and design.

  5. Screening coal combustion fly ashes for application in geopolymers

    NARCIS (Netherlands)

    Valcke, S.L.A.; Pipilikaki, P.; Sarabér, A.J.; Fischer, H.R.; Nugteren, H.W.

    2013-01-01

    Driven by cost and sustainability, secondary resource materials such as fly ash, blast furnace slag, and bottom ash are increasingly used for alternative types of concrete binders, such as geopolymers. Because secondary resources may be highly variable from the perspective of geopolymers, it is ofte

  6. Treatment of Cu-containing wastewater by activated carbon/coal fly ash%活性炭/粉煤灰处理含铜废水的研究

    Institute of Scientific and Technical Information of China (English)

    黄晓丹; 薛美香; 李先学

    2015-01-01

    采用活性炭/粉煤灰处理模拟含铜废水,考察pH、吸附时间、吸附温度、投加量、质量比、活性炭、粉煤灰粒径、铜离子浓度等对吸附效果的影响。结果表明,单纯粉煤灰的吸附效果较差,但100目的粉煤灰与100目的活性炭混合,其吸附效果接近于纯活性炭。活性炭/粉煤灰处理100 mL、30 mg/L模拟含铜废水的最佳吸附条件为:吸附时间3 h,pH 6,吸附温度45℃,活性炭/粉煤灰(质量比1∶1)投加量2.5 g,活性炭和粉煤灰粒径均为100目。在此条件下,铜离子去除率可达97.33%,处理后水中铜离子浓度(0.8114 mg/L)低于国家二级排放标准(1.0 mg/L)。%Cu-containing wastewater was treated by activated carbon/coal fly ash and the impact of solu-tion pH value, adsorption time, temperature, the dosage, the mass ratio, particle size of activated carbon and coal fly ash,and concentration of copper ions on the Cu adsorption capacity were investigated. Results showed that the adsorption effect of copper ion by coal fly ash alone was poor,but when 100 mesh coal fly ash mixed with 100 mesh activated carbon, the adsorption effect was closed to pure activated carbon. 100 mL 30 mg/L simulated Cu-containing wastewater the best adsorption conditions of activated carbon/coal fly ash were pH value of 6,the 2. 5 g dosage of activated carbon/coal fly ash(mass ratio of 1∶1),ac-tivated carbon/coal fly ash particle size of 100 mesh after 3 h contacting at 45℃. Under these conditions, the removal rate of copper ion can reach 97. 33%,and the copper ions concentration(0. 811 4 mg/L) in the treated water were lower than the national emission standards(1. 0 mg/L).

  7. Fly Ash Disposal in Ash Ponds: A Threat to Ground Water Contamination

    Science.gov (United States)

    Singh, R. K.; Gupta, N. C.; Guha, B. K.

    2016-07-01

    Ground water contamination due to deposition of fly ash in ash ponds was assessed by simulating the disposal site conditions using batch leaching test with fly ash samples from three thermal power plants. The periodic analysis of leachates was performed for selected elements, Fe, Cu, Ni, Cr, Pb and Cd in three different extraction solutions to determine the maximum amount that can be leached from fly ash. It was observed that at low pH value, maximum metals are released from the surface of the ash into leachate. The average concentration of these elements found in ground water samples from the nearby area of ash ponds shows that almost all the metals except `Cr' are crossing the prescribed limits of drinking water. The concentration of these elements at this level can endanger public health and environment.

  8. Fly Ash Disposal in Ash Ponds: A Threat to Ground Water Contamination

    Science.gov (United States)

    Singh, R. K.; Gupta, N. C.; Guha, B. K.

    2016-09-01

    Ground water contamination due to deposition of fly ash in ash ponds was assessed by simulating the disposal site conditions using batch leaching test with fly ash samples from three thermal power plants. The periodic analysis of leachates was performed for selected elements, Fe, Cu, Ni, Cr, Pb and Cd in three different extraction solutions to determine the maximum amount that can be leached from fly ash. It was observed that at low pH value, maximum metals are released from the surface of the ash into leachate. The average concentration of these elements found in ground water samples from the nearby area of ash ponds shows that almost all the metals except `Cr' are crossing the prescribed limits of drinking water. The concentration of these elements at this level can endanger public health and environment.

  9. Road Performance of Fly Ash Slag Cement with Low Activity%水泥低活性粉煤灰钢渣路用性能试验研究

    Institute of Scientific and Technical Information of China (English)

    王志刚

    2011-01-01

    In order to study the road performance of fly ash slag cement with low activity,unconfined compressive strength,dry shrinkage property,flushing performance,anti-fatigue property are tested.The experimental data show that road performance of fly ash slag cement with activity is superior to steel slag and fly ash cement.It is suggested that fly ash slag cement with low activity should be adopted in road base construction in conditioned regions.%为研究水泥低活性粉煤灰钢渣路用性能,对其抗压强度、干缩性能、冲刷性能、抗疲劳性能进行了室内试验研究,数据分析表明水泥低活性粉煤灰钢渣路用性能优越于水泥钢渣和粉煤灰,因此,建议有条件的地区,道路基层施工可采用水泥低活性粉煤灰钢渣。

  10. Amelioration of soil PAH and heavy metals by combined application of fly ash and biochar

    Science.gov (United States)

    Masto, Reginald; George, Joshy; Ansari, Md; Ram, Lal

    2016-04-01

    Generation of electricity through coal combustion produces huge quantities of fly ash. Sustainable disposal and utilization of these fly ash is a major challenge. Fly ash along with other amendments like biochar could be used for amelioration of soil. In this study, fly ash and biochar were used together for amelioration of polycyclic aromatic hydrocarbon (PAH) contaminated soil. Field experiment was conducted to investigate the effects of fly ash and biochar on the amelioration of soil PAH, and the yield of Zea mays. The treatments were control, biochar (4 t/ha), fly ash (4 t/ha), ash + biochar ( 2 + 2 t/ha). Soil samples were collected after the harvest of maize crop and analysed for chemical and biological parameters. Thirteen PAHs were analysed in the postharvest soil samples. Soil PAHs were extracted in a microwave oven at 120 °C using hexane : acetone (1:1) mixture. The extracted solutions were concentrated, cleaned and the 13 PAHs [Acenaphthene (Ace), fluorene (Flr), phenanthrene (Phn), anthracene(Ant), pyrene(Pyr), benz(a)anthracene (BaA), chrysene (Chy), benzo(b)fluoranthene (BbF), benzo(k)fluoranthene (BkF), benzo(a)pyrene, benzo(g,h,i)perylene (BghiP), dibenzo(a,h)anthracene, and indeno(1,2,3-cd)pyrene)(Inp)] were analysed using GC-MS. The mean pH increased from 6.09 in control to 6.64 and 6.58 at biochar and fly ash treated soils, respectively. N content was not affected, whereas addition of biochar alone and in combination with fly ash, has significantly increased the soil organic carbon content. P content was almost double in combined (9.06 mg/kg) treatment as compared to control (4.32 mg/kg). The increase in K due to biochar was 118%, whereas char + ash increased soil K by 64%. Soil heavy metals were decreased: Zn (‑48.4%), Ni (‑41.4%), Co (‑36.9%), Cu (‑35.7%), Mn (‑34.3%), Cd (‑33.2%), and Pb (‑30.4%). Soil dehydrogenase activity was significantly increased by ash and biochar treatments and the maximum activity was observed for the

  11. Alkaline bioleaching of municipal solid waste incineration fly ash by autochthonous extremophiles.

    Science.gov (United States)

    Ramanathan, Thulasya; Ting, Yen-Peng

    2016-10-01

    The increasing demand for energy and the generation of solid waste have caused an alarming rise in fly ash production globally. Since heavy metals continue to be in demand for the production of materials, resource recovery from the recycling of these wastes has the potential to delay the depletion of natural ores. The use of microorganisms for the leaching of metals, in a process called bioleaching, is an eco-friendly and economical way to treat the metal-laden wastes. Bioleaching of fly ash is challenging due largely to the alkaline nature and toxic levels of heavy metals which are detrimental to microbial growth and bioleaching activity. The present work reports the isolation of indigenous bacteria from a local fly ash landfill site and their bioleaching performance. 38 autochthonous strains of bacteria were isolated from eight samples collected and plated on five different media. 18 of the isolates showed bioleaching potential, with significant alkaline pH or fly ash tolerance. Genetic characterization of the strains revealed a dominance of Firmicutes, with Alkalibacterium sp. TRTYP6 showing highest fly ash tolerance of up to 20% w/v fly ash, and growth over a pH range 8-12.5. The organism selectively recovered about 52% Cu from the waste. To the best of our knowledge, this is the first time a study on bioleaching with extreme alkaliphiles is reported. PMID:27362528

  12. Reuse of alkali from bio fly ash; Alkaligenanvendelse fra bioflyveaske

    Energy Technology Data Exchange (ETDEWEB)

    Thomsen, Kaj; Jensen, Joergen Peter; Simonsen, Peter; Sander, B.

    2006-03-15

    Experiments to leach potassium salts from fly ash from straw combustion were performed. The fly ash was produced in the bio mass boiler at the Avedoere power plant in south western Copenhagen, Denmark. The fly ash contained approximately 90 mass percent water soluble material. When the fly ash was dissolved at low pH, a slightly higher solubility was found. 100 gram fly ash consisted typically of 9 gram insoluble material, 9 gram calcium phosphate, 29 gram potassium sulfate and 53 gram of potassium chloride. In addition, 100 gram of fly ash contained approximately 1 mg of cadmium, corresponding to a concentration of cadmium of 10 ppm in the fly ash. Fly ash from the bio mass boiler at the Avedoere power plant apparently has a significantly larger content of potassium salts than fly ash from other boilers. The Extended UNIQUAC thermodynamic model was used for calculating relevant phase diagrams and calculations of the necessary amount of water required for dissolving all the KCl and all KCl + K{sub 2}SO{sub 4} of the fly ash. This theoretical minimum amount of water was calculated at a range of temperatures between 10 and 100 deg. C. The amount of water required at 100 deg. C was less than half of that required at 10 deg. C. Experiments were performed in order to find a feasible method for separating the potassium salts of the fly ash from the ash residue and especially from the soluble cadmium salts found in the fly ash. Experiments with counter current leaching of fly ash in a fluid bed gave unsatisfactory results. Apparently there was a lack of contact between the wash water and the ash. In addition, sedimentation was very slow resulting in an incomplete separation of wash water and ash residue. Experiments with ion exchange by adding CaCl{sub 2} to the wash water and successive precipitation of gypsum or anhydrite gave unsatisfactory results. Process simulation had shown that by this method the necessary amount of washing water could be decreased. This is due to

  13. Influence of Utilization of High-Volumes of Class F Fly Ash on the Abrasion Resistance of Concrete

    Directory of Open Access Journals (Sweden)

    William PRINCE

    2007-01-01

    Full Text Available Utilization of large volumes of fly ash in various concrete applications is a becoming a more general practice in an efforts towards using large quantities of fly ash. Around the world, Class C or Class F or both as available have been used in high volumes in cement-based materials. In India, majority of fly generated is of Class F type as per ASTM C 618. Yearly fly ash generation in India is approximately 95 million tonnes. Out of which around 15-20% is utilized in cement production and cement/concrete related activities. In order to increase its percentage utilization, an investigation was carried out to use it in concrete.In this paper, abrasion resistance of high volume fly ash (HVFA concretes made with 35, 45, 55, and 65% of cement replacement was evaluated in terms of its relation with compressive strength. Comparison was made between ordinary Portland cement and fly ash concrete. Test results indicated that abrasion resistance of concrete having cement replacement up to 35 percent was comparable to the normal concrete mix with out fly ash. Beyond 35% cement replacement, fly ash concretes exhibited slightly lower resistance to abrasion relative to non-fly ash concretes. Test results further indicated that abrasion resistance of concrete is closely related with compressive strength, and had a very good correlation between abrasion resistance and compressive strength (R2 value between 0.9018 and 0.9859 depending upon age.

  14. Availability of sulfur in fly ash to plants

    Energy Technology Data Exchange (ETDEWEB)

    Elseewi, A.A.; Bingham, F.T.; Page, A.L.

    1978-01-01

    Fly ash from a coal-fired power plant was added to soil in variable amounts and the availability of sulfur to a variety of plant species from this source was compared to that of gypsum. The study was conducted under greenhouse conditions with a calcareous and two acid soils which were low in plant-available sulfur. The fly ash used contained 0.4% S, all of which is extractable by NH/sub 4/OAc. When mixed with a calcareous and an acid soil at rates of 1 to 2% by weight, the fly ash corrected a S deficiency in the soil and maximized the yield of alfalfa (Medicago sativa L.) and bermudagrass (Cynodon dactylon L.). The increase in yield (twofold to threefold in alfalfa and 40 to 70% in bermudagrass) was accompanied by an increase in the S content of the plant tops from a deficiency level (<0.1%) to a sufficiency level (greater than or equal to 0.2%). The availability of fly ash-S and gypsum (CaSO/sub 4/ . 2H/sub 2/O)-S was compared by the addition of equal amounts of S from the two sources (25-, 50-, and 100-mg S/kg soil) to an acid soil. Yield and S content of turnip (Brassica rapa L.) and white clover (Trifolium repens L.) were equally improved, demonstrating that the availability of fly ash derived-S is equivalent to that of gympsum-S.

  15. Alkaline disinfection of urban wastewater and landfill leachate by wood fly ash.

    Science.gov (United States)

    Ivanković, Tomislav; Hrenović, Jasna; Itskos, Grigorios; Koukouzas, Nikolaos; Kovačević, Davor; Milenković, Jelena

    2014-12-01

    Wood fly ash is an industrial by-product of the combustion of different wood materials and is mostly disposed of as waste on landfills. In our preliminary experiments, wood ash exhibited antibacterial activity against urban wastewater bacteria and we focused on wood fly ash as a potential substrate for wastewater disinfection. The addition of ash at a concentration of 10 g L⁻¹ (1%) caused an instant increase of pH in urban wastewater and landfill leachate. High pH (10.1-12.7) inactivated bacterial populations in the wastewater and the removal of faecal coliforms and intestinal enterococci after 6 h of contact was 100% (below the detection limit; ash sample (ash from combustion of beech) both in urban wastewater and landfill leachate. Properly chosen wood fly ash, i.e. one that tends to increase the pH to the greatest extent, proved to be a very effective disinfection substrate. Considering that water treated with wood ash has a high pH and needs to be neutralised before discharge, ash would be suitable for disinfection of leachates when smaller volumes are treated. PMID:25720024

  16. Size fraction characterization of highly-calcareous fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Itskos, Grigorios; Koukouzas, Nikolaos [Institute for Solid Fuels Technology and Applications, Centre for Research and Technology Hellas, 357-359 Mesogeion Avenue, GR-152 31, Halandri, Athens (Greece); Itskos, Socrates [Department of Chemical Technology and the Environment, Steam Electric Station of Amynteon-Filotas, Public Power Corporation of Greece, GR-532 00, Amynteon (Greece)

    2010-11-15

    The chemical and mineralogical composition of lignite fly ash (FA) varies as a function of the prevalent conditions in both the processes of power production and lignite mining. The differentiation of the qualitative and quantitative composition of the highly-calcareous lignite fly ash, as a function of its particle size distribution, is verified in this paper. According to the results of the conducted research, a fine-grained fraction of considerable amount presents properties that obstruct the sustainable exploitation of calcareous lignite fly ash in cement industry applications. On the other hand, the same grain fraction (because of its hydraulic properties) can be utilized in other sort of applications, based on different criteria, i.e. in road constructions. The coarse-grained fraction (which reflects a low proportion to the total fly ash output) presents the same undesired characteristics as well. Rather, the intermediate grain fraction (75-150 {mu}m) presents the highly desirable properties when fly ash is utilized as a pozzolanic additive. In addition, the mechanism of the formation of the intermediate grain fraction strongly prevents the factors that cause the variation of fly ash-quality. It is therefore the optimum part of the whole amount of lignite FA, to be utilized as additive in cement manufacturing. The outcomes of this paper will hopefully contribute towards the crucial goal of the expansion of the utilization of calcareous lignite fly ash by proposing a more effective way of using this material, basically by taking advantage of its fundamental chemical and mineralogical properties. (author)

  17. Radiological significance of coal, slag and fly ash samples from the Eastern Black Sea region

    International Nuclear Information System (INIS)

    This work presents a study of natural radioactivity levels in coal and its combustion residues (fly ash and slag) used in the houses in Black Sea Region, Turkey. Coal, fly ash and slag samples were provided from different locations of the region and analyzed by gamma spectroscopy using a high-purity germanium detector (HPGe). Also, chemical analyses of these samples were carried out using energy dispersive X-ray fluorescence spectrometer. The mean 226Ra activity concentrations in coal, slag and fly ash were measured as 83, 99 and 38 Bq kg-1, respectively. The mean 232Th activity concentrations in coal, slag and fly ash were measured as 108, 113 and 50 Bq kg-1, respectively. The mean 40K activity concentrations in coal, slag and fly ash were found to be 366, 381 and 204 Bq kg-1, respectively. The potential radiological hazards associated to these materials were evaluated by calculating the radium equivalent activity (Raeq), the air absorbed gamma dose rate (D), the annual effective dose rate (AED), the external hazard index (Hex) and internal hazard index (Hin) and compared with the internationally accepted or reference values. The mean Raeq values of the coal, fly ash and slag samples were lower than the recommended maximum values 370 Bq kg-1 by the Organization for Economic Cooperation and Development (OECD). The overall mean outdoor terrestrial gamma air absorbed dose rate in coal, fly ash and slag samples are 119, 129 and 62 nGy h-1 and the corresponding outdoor annual effective doses are 0.60, 0.32 and 0.64 mSv y-1, which is higher than the worldwide average (0.07 mSv y-1), respectively. Moreover, the enrichment factors relative to the input coal are calculated for the radionuclide contents observed. Calculated enrichment factor values for 226Ra and 232Th were found 1.14 and 1.01, respectively. (orig.)

  18. Variations in organic carbon, aggregation, and enzyme activities of gangue-fly ash-reconstructed soils with sludge and arbuscular mycorrhizal fungi during 6-year reclamation.

    Science.gov (United States)

    Yin, Ningning; Zhang, Zhen; Wang, Liping; Qian, Kuimei

    2016-09-01

    Mining activities can cause drastic disturbances in soil properties, which adversely affect the nutrient cycling and soil environment. As a result, many efforts have been made to explore suitable reclamation strategies that can be applied to accelerate ecology restoration. In this study, we reconstructed mine soils with fly ash, gangue, sludge, planted ryegrass, and inoculated arbuscular mycorrhizal fungi (AMF) in Pangzhuang mine of Xuzhou during 2009 to 2015. The soil aggregation process, enzyme activities (i.e., invertase, urease and acid phosphatase activities), soil organic carbon (SOC) as well as other soil nutrients such as nitrogen, phosphorus, and potassium contents of the reconstructed mine soils were monitored during 6-year reclamation. The integrated application of sludge and AMF led to a promising reclamation performance of mining areas, in which soil aggregate stability, enzyme activities, SOC, and ryegrass biomass were effectively enhanced. The micro-aggregates ( 0.25 mm) during the reclamation, indicating that macro-aggregates were gradually formed from micro-aggregates during the pedogenesis of reconstructed mine soils. The correlation analysis shows that SOC contents in aggregate fraction of 0.25∼0.5 mm were correlated with aggregate distribution and enzyme activities. Enzyme activities, however, were not significantly correlated with aggregate distribution. The outcomes from the present study could enrich our understanding on soil property changes in pedogenesis process of reconstructed mine soils, and meanwhile, the employment of sludge combined with AMF is suggested to be an effective alternative for the mine soil reclamation.

  19. Variations in organic carbon, aggregation, and enzyme activities of gangue-fly ash-reconstructed soils with sludge and arbuscular mycorrhizal fungi during 6-year reclamation.

    Science.gov (United States)

    Yin, Ningning; Zhang, Zhen; Wang, Liping; Qian, Kuimei

    2016-09-01

    Mining activities can cause drastic disturbances in soil properties, which adversely affect the nutrient cycling and soil environment. As a result, many efforts have been made to explore suitable reclamation strategies that can be applied to accelerate ecology restoration. In this study, we reconstructed mine soils with fly ash, gangue, sludge, planted ryegrass, and inoculated arbuscular mycorrhizal fungi (AMF) in Pangzhuang mine of Xuzhou during 2009 to 2015. The soil aggregation process, enzyme activities (i.e., invertase, urease and acid phosphatase activities), soil organic carbon (SOC) as well as other soil nutrients such as nitrogen, phosphorus, and potassium contents of the reconstructed mine soils were monitored during 6-year reclamation. The integrated application of sludge and AMF led to a promising reclamation performance of mining areas, in which soil aggregate stability, enzyme activities, SOC, and ryegrass biomass were effectively enhanced. The micro-aggregates ( 0.25 mm) during the reclamation, indicating that macro-aggregates were gradually formed from micro-aggregates during the pedogenesis of reconstructed mine soils. The correlation analysis shows that SOC contents in aggregate fraction of 0.25∼0.5 mm were correlated with aggregate distribution and enzyme activities. Enzyme activities, however, were not significantly correlated with aggregate distribution. The outcomes from the present study could enrich our understanding on soil property changes in pedogenesis process of reconstructed mine soils, and meanwhile, the employment of sludge combined with AMF is suggested to be an effective alternative for the mine soil reclamation. PMID:27250093

  20. Structural and Mechanical Characterization of Sustainable Composites Based on Recycled and Stabilized Fly Ash

    Directory of Open Access Journals (Sweden)

    Stefano Besco

    2014-08-01

    Full Text Available This paper reports the results on the use of an innovative inert, based on stabilized fly ash from municipal solid waste incineration as a filler for polypropylene. The starting material, which contains large quantities of leachable Pb and Zn, was stabilized by means of an innovative process using rice husk ash as a waste silica source, together with other fly ashes, such as coal fly ash and flue gas desulfurization residues. The use of all waste materials to obtain a new filler makes the proposed technology extremely sustainable and competitive. The new composites, obtained by using the stabilized material as a filler for polypropylene, were characterized and their mechanical properties were also investigated. A comparison with a traditional polypropylene and calcium carbonate based compound was also done. This research activity was realized in the frame of the COSMOS-RICE project, financed by the EU Commission.

  1. A study on fiy ash: ballistic separation of a fly ash

    OpenAIRE

    Peris Mora, Eduardo; Payá, Jordi; Monzó, José

    1991-01-01

    The object of this study is the characterization of several sized fractions from a "spanish fly ash" originating in the thermoelectric power plant in Andorra (Teruel). Physical (size distributions, densities) chemical (chemical composition) and mineralogical characteristics (X-ray diffractograms and infrared spectra) for those sized fractions have been analyzed. Initial fly ash was ballistically separated (horizontal draft) into four fractions using an aerodynamic tunnel with hori...

  2. Performance of coal fly-ash based oxygen carrier for the chemical looping combustion of synthesis gas

    International Nuclear Information System (INIS)

    Highlights: • Fly-ash based oxygen carriers were synthesised for chemical looping combustion of synthesis gas. • Using fly-ash as the support of the oxygen carrier enhanced the thermal stability and oxidant transfer for fuel oxidation. • Fly-ash based nickel oxide reformed hydrocarbons into carbon monoxide with the presence of carbon dioxide. - Abstract: The performance of coal fly-ash based oxygen carriers for chemical looping combustion of synthesis gas has been investigated using both a thermogravimetric analyser and a packed bed reactor. Oxygen carriers with 50 wt% active metal compounds, including copper, nickel and iron oxides, supported on coal fly-ash were synthesised using the deposition–precipitation method. Copper oxide and nickel oxide supported on fly-ash showed high oxygen transfer efficiency and oxygen carrying capacity at 800 °C. The fly-ash based nickel oxide was effective in reforming hydrocarbons and for the conversion of carbon dioxide into carbon monoxide; a nickel complex with silicate was identified as a minor phase following the reduction reaction. The fly-ash based iron oxide showed various reduction steps and resulted in an extended reduction time. The carbon emission at the oxidation stage was avoided by reducing the length of the exposure to the reduction gas

  3. Hierarchical zeolites from class F coal fly ash

    Science.gov (United States)

    Chitta, Pallavi

    Fly ash, a coal combustion byproduct is classified as types class C and class F. Class C fly ash is traditionally recycled for concrete applications and Class F fly ash often disposed in landfills. Class F poses an environmental hazard due to disposal and leaching of heavy metals into ground water and is important to be recycled in order to mitigate the environmental challenges. A major recycling option is to reuse the fly ash as a low-cost raw material for the production of crystalline zeolites, which serve as catalysts, detergents and adsorbents in the chemical industry. Most of the prior literature of fly ash conversion to zeolites does not focus on creating high zeolite surface area zeolites specifically with hierarchical pore structure, which are very important properties in developing a heterogeneous catalyst for catalysis applications. This research work aids in the development of an economical process for the synthesis of high surface area hierarchical zeolites from class F coal fly ash. In this work, synthesis of zeolites from fly ash using classic hydrothermal treatment approach and fusion pretreatment approach were examined. The fusion pretreatment method led to higher extent of dissolution of silica from quartz and mullite phases, which in turn led to higher surface area and pore size of the zeolite. A qualitative kinetic model developed here attributes the difference in silica content to Si/Al ratio of the beginning fraction of fly ash. At near ambient crystallization temperatures and longer crystallization times, the zeolite formed is a hierarchical faujasite with high surface area of at least 360 m2/g. This work enables the large scale recycling of class F coal fly ash to produce zeolites and mitigate environmental concerns. Design of experiments was used to predict surface area and pore sizes of zeolites - thus obviating the need for intense experimentation. The hierarchical zeolite catalyst supports tested for CO2 conversion, yielded hydrocarbons

  4. Unburned Carbon Loss in Fly Ash of CFB Boilers Burning Hard Coal

    Institute of Scientific and Technical Information of China (English)

    L(U) Junfu(吕俊复); WANG Qimin(王启民); LI Yong(黎永); YUE Guangxi(岳光溪); Yam Y.Lee; Baldur Eliasson; SHEN Jiezhong(沈解忠); YU Long(于龙)

    2003-01-01

    The unburned carbon loss in fly ash of circulating fluidized bed (CFB) boilers, most of which are burning active fuels such as lignite or peat, is normally very low. However, most CFB boilers in China usually burn hard coals such as anthracite and bituminous coal and coal wastes, so the carbon content in the fly ash from these boilers is higher than expected. This paper investigates the source of unburned carbon in the fly ash of CFB boilers burning hard coal through a series of field tests and laboratory investigations. The char behavior during combustion, including fragmentation and deactivation, which is related to the parent coal, has an important impact on the carbon burnout in CFB boilers. The research shows that char deactivation occurs during char burnout in fluidized bed combustion, especially for large particles of low rank coal. The uneven mixing of solids and air in the core region of the furnace also causes poor burnout of carbon in CFB fly ash. An index describing the volatile content (as dry ash free basis) over the heating value is proposed to present the coal rank. The coal combustion efficiency is shown to be strongly connected with this coal index. Several changes in the CFB boiler design are suggested to reduce the unburned carbon loss in the fly ash.

  5. Electrodialytic removal of Cd from biomass combustion fly ash suspensions

    DEFF Research Database (Denmark)

    Kirkelund, Gunvor M.; Ottosen, Lisbeth M.; Damoe, Anne J.

    2013-01-01

    was investigated with the aim of enabling reuse of the ashes. The ashes originated from combustion of straw (two ashes), wood chips, and co-firing of wood pellets and fuel oil, respectively. A series of laboratory scale electrodialytic remediation experiments were conducted with each ash. The initial Cd......Due to relatively high concentrations of Cd, biomass combustion fly ashes often fail to meet Danish legislative requirements for recycling as fertilizer. In this study, the potential of using electrodialytic remediation for removal of Cd from four different biomass combustion fly ashes...... the final Cd concentration was below 2.0. mg Cd/kg DM in at least one experiment done with each ash. This was obtained within 2 weeks of remediation and at liquid to solid (L/S) ratios of L/S 16 for the pre-washed straw ash and L/S 8 for the straw, co-firing and wood ash. © 2013 Elsevier B.V....

  6. Evaluation and Treatment of Coal Fly Ash for Adsorption Application

    Directory of Open Access Journals (Sweden)

    Samson Oluwaseyi BADA

    Full Text Available Many researchers had investigated fly ash as an adsorbent for the uptake of organic compounds from petrochemical waste effluents. The availability, inexpensive and its adsorption characteristic had made it an alternative media for the removal of organic compounds from aqueous solution. The physical property of South African Coal Fly Ash (SACFA was investigated to determine its adsorption capability and how it can be improved. Chemical treatment using 1M HCl solution in the ratio of (1 g fly ash to (2 ml of acid was used and compared with untreated heat-treated samples. The chemically treated fly ash has a higher specific surface area of 5.4116 m2/g than the heat-treated fly ash with 2.9969 m2/g. More attention had to be given to the utilization of SACFA for the treatment of wastewaters containing organic compounds through the application of Liquid phase adsorption process that was considered as an inexpensive and environmentally friendly technology.

  7. Characteristics of the ultrafine component of fly ash

    Energy Technology Data Exchange (ETDEWEB)

    M.R. Jones; A. McCarthy; A.P.P.G. Booth [University of Dundee, Dundee (United Kingdom). Concrete Technology Unit, Division of Civil Engineering

    2006-11-15

    Post-production processing of fly ash (FA) is an important issue for its use in concrete. Given (i) the need for environmental protection, (ii) the measures being applied on coal-fired power stations to reduce acidic gas emissions and (iii) the effect these have had on fly ash quality, there is a need to consider efficient post-production processing to enhance fly ash characteristics. This is particularly important for fly ash used as a cement in concrete production, since the additional residual carbon content and decreased fineness significantly affect its quality. This paper details the material characteristics of an ultrafine, low-lime fly ash (UF-FA), produced, in this case, by processing a coarse FA (referred to as parent FA) from a bituminous coal-fired power station via air-cyclonic separation. The UF-FA is shown to have much improved material characteristics compared to the parent FA in terms of morphology, mineralogy and chemical composition. Further results are presented on the effect of UF-FA on the properties of cementitious systems. Improved consistence and compressive strengths of combined Portland cement (PC) and UF-FA mortars were observed, whilst enhanced PC hydration and a high degree of FA reactivity were concluded from heat of hydration measurements and calcium hydroxide contents of pastes. 20 refs., 10 figs., 1 tab.

  8. The use of fly ash the thermal power plants in the construction

    Science.gov (United States)

    Fediuk, R. S.; Yushin, A. M.

    2015-10-01

    The problems of ecological and radiation safety of the construction of man-made waste like fly ash thermal power plants were researched. The chemical composition of TPPs ashes of Primorsky Territory was studied, defined their specific effective activity of natural radionuclides. The most modern research methods were used - differential thermal analysis, thermogravimetry, X-ray analysis. It was revealed that the ash of the Primorskaya TPP and Partizanskaya TPP has exceed the permissible parameters of radioactivity, so not suitable for use in construction. Ashes of Vladivostok TPP-2 and Artem TPP of Primorsky Region on parameters radioactivity and chemical composition have suitable for use as a filler in the concrete.

  9. Influence of Fly Ash, Bottom Ash, and Light Expanded Clay Aggregate on Concrete

    Directory of Open Access Journals (Sweden)

    S. Sivakumar

    2015-01-01

    Full Text Available Invention of new methods in strengthening concrete is under work for decades. Developing countries like India use the extensive reinforced construction works materials such as fly ash and bottom ash and other ingredients in RCC construction. In the construction industry, major attention has been devoted to the use of fly ash and bottom ash as cement and fine aggregate replacements. In addition, light expanded clay aggregate has been introduced instead of coarse aggregate to make concrete have light weight. This paper presents the results of a real-time work carried out to form light weight concrete made with fly ash, bottom ash, and light expanded clay aggregate as mineral admixtures. Experimental investigation on concrete mix M20 is done by replacement of cement with fly ash, fine aggregate with bottom ash, and coarse aggregate with light expanded clay aggregate at the rates of 5%, 10%, 15%, 20%, 25%, 30%, and 35% in each mix and their compressive strength and split tensile strength of concrete were discussed for 7, 28, and 56 days and flexural strength has been discussed for 7, 28, and 56 days depending on the optimum dosage of replacement in compressive strength and split tensile strength of concrete.

  10. CO2 capture using fly ash from coal fired power plant and applications of CO2-captured fly ash as a mineral admixture for concrete.

    Science.gov (United States)

    Siriruang, Chaichan; Toochinda, Pisanu; Julnipitawong, Parnthep; Tangtermsirikul, Somnuk

    2016-04-01

    The utilization of fly ash as a solid sorbent material for CO2 capture via surface adsorption and carbonation reaction was evaluated as an economically feasible CO2 reduction technique. The results show that fly ash from a coal fired power plant can capture CO2 up to 304.7 μmol/g fly ash, consisting of 2.9 and 301.8 μmol/g fly ash via adsorption and carbonation, respectively. The CO2 adsorption conditions (temperature, pressure, and moisture) can affect CO2 capture performance of fly ash. The carbonation of CO2 with free CaO in fly ashes was evaluated and the results indicated that the reaction consumed most of free CaO in fly ash. The fly ashes after CO2 capture were further used for application as a mineral admixture for concrete. Properties such as water requirement, compressive strength, autoclave expansion, and carbonation depth of mortar and paste specimens using fly ash before and after CO2 capture were tested and compared with material standards. The results show that the expansion of mortar specimens using fly ash after CO2 capture was greatly reduced due to the reduction of free CaO content in the fly ash compared to the expansion of specimens using fresh fly ash. There were no significant differences in the water requirement and compressive strength of specimens using fly ash, before and after CO2 capture process. The results from this study can lead to an alternative CO2 capture technique with doubtless utilization of fly ash after CO2 capture as a mineral admixture for concrete. PMID:26803257

  11. CO2 capture using fly ash from coal fired power plant and applications of CO2-captured fly ash as a mineral admixture for concrete.

    Science.gov (United States)

    Siriruang, Chaichan; Toochinda, Pisanu; Julnipitawong, Parnthep; Tangtermsirikul, Somnuk

    2016-04-01

    The utilization of fly ash as a solid sorbent material for CO2 capture via surface adsorption and carbonation reaction was evaluated as an economically feasible CO2 reduction technique. The results show that fly ash from a coal fired power plant can capture CO2 up to 304.7 μmol/g fly ash, consisting of 2.9 and 301.8 μmol/g fly ash via adsorption and carbonation, respectively. The CO2 adsorption conditions (temperature, pressure, and moisture) can affect CO2 capture performance of fly ash. The carbonation of CO2 with free CaO in fly ashes was evaluated and the results indicated that the reaction consumed most of free CaO in fly ash. The fly ashes after CO2 capture were further used for application as a mineral admixture for concrete. Properties such as water requirement, compressive strength, autoclave expansion, and carbonation depth of mortar and paste specimens using fly ash before and after CO2 capture were tested and compared with material standards. The results show that the expansion of mortar specimens using fly ash after CO2 capture was greatly reduced due to the reduction of free CaO content in the fly ash compared to the expansion of specimens using fresh fly ash. There were no significant differences in the water requirement and compressive strength of specimens using fly ash, before and after CO2 capture process. The results from this study can lead to an alternative CO2 capture technique with doubtless utilization of fly ash after CO2 capture as a mineral admixture for concrete.

  12. Monitoring of radioactive nuclides in incinerator fly ash and adsorption of Cs in simulated and actual eluate of the fly ash onto clay and soil

    International Nuclear Information System (INIS)

    Radioactive nuclides in the incinerator fly ash of municipal solid waste was determined and monitored. For leaching radioactive Cs from incinerating fly ash in reclaimed land, a modified No. 13 elution test and adsorption with stable Cs onto andosol were performed. The activity concentration of radioactive nuclides in incinerator fly ash was constant within the range of the activity concentration before the accident at Fukushima Daiichi Nuclear Power Station. The 134Cs/137Cs activity concentration ratio was almost equal to 1, corresponding to 137Cs existing in environment before the accident. 40% of 137Cs in incinerator fly ash eluted with the modified No. 13 elution test, and adsorption ratio of Cs+ onto the andosol showed 90% as being the primary concentration was equal to or more than 5000 μg L−1. In addition, the desorption results used for 5 types of solvent showed that desorption ratio of adsorbed Cs+ from the soil was 3.6% at the maximum. Hence, it is anticipated that using a soil that is similar in composition to the andosol suppresses the leaching out of radioactive Cs from reclaimed land. (author)

  13. Radiochemical tecniques applied to laboratory studies of water leaching of heavy metals from coal fly ash

    International Nuclear Information System (INIS)

    Assessment of the potential environmental impact of heavy metals (HM) mobilized by coal-fired plants showed that water leaching of HM from pulverized fuel ash may for certain HM constitute an important pathway to the aquatic environment. This process was therefore investigated in more detail by laboratory experiments. Batch experiments were performed in order to simulate ash pond conditions, whereas column experiments were carried out to represent water leaching from fly ash deposits. Using highly sensitive radiochemical techniques such as radioactive tracers and neutron activation of fly ash the fate of a single HM could be easily followed even in very low concentration experiments. Employing radioisotopic tracers the distribution coefficients of simple ionic forms of As, Sb, Bi, Se, Te, Cr, Mo, W, Ni, Cd in a coal fly ash/water system could be determined as a function of pH. Results obtained on the absorption and desorption behaviour of HM on coal fly ash can be explained in part on the basis of the surface predominance and the aqueous chemistry of single ionic, mainly anionic, forms of the relative elements. But ion exchange and coprecipitation phenomena also seem to be important processes. The nature and concentration of ions contained originally in the water used (distilled water, fly ash leachate and seawater) were found to have a strong influence on the sorptive behaviour of HM on coal ashes. The high degree of applicability of radiochemical and nuclear techniques to coal ash water leaching problems has been demonstrated and further points for subsequent research in this field possibly using nuclear techniques are indicated. (author)

  14. Stability and leaching of cobalt smelter fly ash

    DEFF Research Database (Denmark)

    Vítková, Martina; Hyks, Jiri; Ettler, Vojtěch;

    2013-01-01

    The leaching behaviour of fly ash from a Co smelter situated in the Zambian Copperbelt was studied as a function of pH (5–12) using the pH-static leaching test (CEN/TS 14997). Various experimental time intervals (48h and 168h) were evaluated. The leaching results were combined with the ORCHESTRA...... elements, the released concentrations were very similar after 48h and 168h, indicating near-equilibrium conditions in the system. Calcite, clinopyroxenes, quartz and amorphous phases predominated in the fly ash. Various metallic sulfides, alloys and the presence of Cu, Co and Zn in silicates and glass were...... and Cu. However, there is a high risk of Co, Cu, Pb and Zn mobility in the acidic soils around the smelter facility. Therefore, potential local options for “stabilisation” of the fly ash were evaluated on the basis of the modelling results using the PHREEQC code....

  15. Current Methods to Detoxify Fly Ash from Waste Incineration

    Energy Technology Data Exchange (ETDEWEB)

    Hallgren, Christine; Stroemberg, Birgitta [TPS Termiska Processer AB, Nykoeping (Sweden)

    2004-07-01

    Fly ash from waste incineration contains large amounts of heavy metals and dioxins, which will cause a significant disposal problem within the coming years. The amount of fly ash produced in Sweden is currently approximately 60,000 tons/y. New technological options for the decontamination and/or inertization of incinerator fly ash are being developed with the objective of rendering a product that can be reused or, at least, be deposited at standard landfill sites with no risk. Many of these technologies have been tested at industrial scale or in pilot projects. The proposed alternatives include: Thermal treatments; Immobilization/stabilization by cement based techniques; Wet chemical treatments (extractions, immobilizations); Microbiological treatments. Of these, thermal treatments are the most promising solution. Depending on the temperature thermal treatments are classified in two main types: 1) low temperature (below 600 deg C) thermal treatments and 2) high temperature (above 1200 deg C) thermal treatments (vitrification). Most dioxins can be successfully destroyed at temperatures up to 400 deg C under oxygen deficient conditions and at temperatures up to 600 deg C under oxidising conditions. However most heavy metals remain in the fly ash after low temperature treatment. At a temperature of 900 deg C most heavy metals can also be removed in a 10% HCl atmosphere by forming volatile metal chlorides (CT-Fluapur process). During vitrification processes the fly ash melts and forms an inert glassy slag. The product does not leach any significant amount of heavy metals and is free from dioxin. The volume of the fly ash is significantly reduced. The product can be land filled at low costs or used as construction material. The properties of the product depend on the cooling process and on additives such as sand, limestone or waste glass. A series of vitrification methods at industrial size or in pilot scale using different furnaces are studied. Among these, plasma

  16. Behaviour of Onobrychis Viciifolia Growing on Fly Ash Experimental Parcels

    Directory of Open Access Journals (Sweden)

    Florica Morariu

    2011-05-01

    Full Text Available Studies were conducted to identify a treatment method for upper layers of fly ash to cover them with vegetation. Fixing plant layer acts against erosion/washes of fly ash deposits. Studies emphasized the need of use of an organic fertilizer mixed with inorganic materials such as volcanic tuff and, also, the need of selecting a plant species compatible with the treated culture medium. The use of an amended variant of compost and modified volcanic tuff of fly ash layers shows that the selected leguminous species, Onobrychis viciifolia, installs itself quickly on the third level of Braun - Blanquet scale. The reduction of toxic heavy metals bioaccumulation from the aerial plant tissues such as lead and nickel of 72-79%, and copper and zinc of 50-68%, respectively, allows obtaining of a safe biomass for wildlife visiting the area.

  17. MATHEMATICAL MODELING FOR DURABILITY CHARACTERISTICS OF FLY ASH CONCRETE

    Directory of Open Access Journals (Sweden)

    JINO JOHN

    2012-01-01

    Full Text Available This paper presents the results obtained from the mathematical modeling for the durability characteristics of fly ash concrete. A mathematical model is employed to predict the saturated water absorption, permeability, sorpitivity and acid resistance of the concrete containing fly ash as a replacement of cement at a range of 0%, 10%, 20%, 30%, 40% and 50 %. This model is valid for mixes with cement quantity 208 to 416 kg/m3, water cement ratio 0.38 to 0.76, flyash 0 to 208 kg/m3 and cement/ total aggregate ratio varying from 0.11 to 0.22. Fly ash content and water cement ratio are the main parameters which influence the durability characteristics. The predicted mathematical model for saturated water absorption, permeability, sorpitivity and acid resistance produced accurate results for the respective ages when compared with the experimental results.

  18. DC Arc Plasma Furnace Melting of Waste Incinerator Fly Ash

    Institute of Scientific and Technical Information of China (English)

    CHEN Mingzhou; MENG Yuedong; SHI Jiabiao; KUANG Jingan; NI Guohua; LIU Wei; JIANG Yiman

    2009-01-01

    Municipal solid waste incinerator (MSWI) fly ash was melted using a set of direct current (DC) arc plasma furnace system for the first time in China.At a feed-rate of flying ash of 80 kg/h,the temperature at the gas outlet was above 1300℃.Dioxins in the off-gas were recorded as 0.029 ng I-TEQ/Nm3 (international toxic equivalent,I-TEQ),well below 0.5 ng TEQ/Nm3 (toxic equivalent,TEQ),while those in the melted product(slag)were 0.00035 ng/g I-TEQ.Molten slag from the furnace showed excellent resistance against the leaching of heavy metals.These results prove that the plasma furnace is effective for the detoxification and stabilization of MSWI fly ash.

  19. Mercury capture by selected Bulgarian fly ashes: Influence of coal rank and fly ash carbon pore structure on capture efficiency

    Science.gov (United States)

    Kostova, I.J.; Hower, J.C.; Mastalerz, Maria; Vassilev, S.V.

    2011-01-01

    Mercury capture by fly ash C was investigated at five lignite- and subbituminous-coal-burning Bulgarian power plants (Republika, Bobov Dol, Maritza East 2, Maritza East 3, and Sliven). Although the C content of the ashes is low, never exceeding 1.6%, the Hg capture on a unit C basis demonstrates that the low-rank-coal-derived fly ash carbons are more efficient in capturing Hg than fly ash carbons from bituminous-fired power plants. While some low-C and low-Hg fly ashes do not reveal any trends of Hg versus C, the 2nd and, in particular, the 3rd electrostatic precipitator (ESP) rows at the Republika power plant do have sufficient fly ash C range and experience flue gas sufficiently cool to capture measurable amounts of Hg. The Republika 3rd ESP row exhibits an increase in Hg with increasing C, as observed in other power plants, for example, in Kentucky power plants burning Appalachian-sourced bituminous coals. Mercury/C decreases with an increase in fly ash C, suggesting that some of the C is isolated from the flue gas stream and does not contribute to Hg capture. Mercury capture increases with an increase in Brunauer-Emmett-Teller (BET) surface area and micropore surface area. The differences in Hg capture between the Bulgarian plants burning low-rank coal and high volatile bituminous-fed Kentucky power plants suggests that the variations in C forms resulting from the combustion of the different ranks also influence the efficiency of Hg capture. ?? 2010 Elsevier Ltd.

  20. Synthesis of a nano-crystalline solid acid catalyst from fly ash and its catalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Chitralekha Khatri; Ashu Rani [Government P.G. College, Kota (India). Environmental Chemistry Laboratory

    2008-10-15

    The synthesis of nano-crystalline activated fly ash catalyst (AFAC) with crystallite size of 12 nm was carried out by chemical and thermal treatment of fly ash, a waste material generated from coal-burning power plants. Fly ash was chemically activated using sulfuric acid followed by thermal activation at 600{sup o}C. The variation of surface and physico-chemical properties of the fly ash by activation methods resulted in improved acidity and therefore, catalytic activity for acid catalyzed reactions. The AFAC was characterized by X-ray diffraction, FT-IR spectroscopy, N{sub 2}-adsorption-desorption isotherm, scanning electron microscopy, flame atomic absorption spectrophotometry and sulfur content by CHNS/O elemental analysis. It showed amorphous nature due to high silica content (81%) and possessed high BET surface area (120 m{sup 2}/g). The catalyst was found to be highly active solid acid catalyst for liquid phase esterification of salicylic acid with acetic anhydride and methanol giving acetylsalicylic acid and methyl salicylate respectively. A maximum yield of 97% with high purity of acetylsalicylic acid (aspirin) and a very high conversion 87% of salicylic acid to methyl salicylate (oil of wintergreen) was obtained with AFAC. The surface acidity and therefore, catalytic activity in AFAC was originated by increased silica content, hydroxyl content and higher surface area as compared to fly ash. The study shows that coal generated fly ash can be converted into potential solid acid catalyst for acid catalyzed reactions. Furthermore, this catalyst may replace conventional environmentally hazardous homogeneous liquid acids making an ecofriendly; solvent free, atom efficient, solid acid based catalytic process. 27 refs., 5 figs., 2 tabs.

  1. Total exchange of Sr-90 in the fly ash for treatment of liquid radioactive waste

    International Nuclear Information System (INIS)

    The determination total exchange capacity 90Sr in the fly ash mineral by fixed bed process has been done. Fly ash is an aluminosilicate mineral with small particles size and porous, so that it can be used to adsorb radioactive pollutants. In this experiment was determined total exchange capacity (K tot) which as the total amount ion adsorbed (counter ions adsorbed eriodictyol ions, etc). The experiment was done by flown the simulation of liquid waste 0.1 M Sr(NO3)2 contain of 90Sr with the activity of 621.6 Bq/cm3 to the column filled of fly ash, then the activity of 90Sr in the effluents were analyzed by O rtec counter apparatus up to steady state condition. The experiment variables are particles size range of fly ash (3). The experiment result were shown that the smaller its particle size and the greater its compacted density could increase the value of K tot Particle size of. 3 resulted the best sorption with value of K tot = 0.967 meg/g. Key words : fly ash, total exchange capacity, 90Sr

  2. Mercury removal from coal combustion flue gas by modified fly ash.

    Science.gov (United States)

    Xu, Wenqing; Wang, Hairui; Zhu, Tingyu; Kuang, Junyan; Jing, Pengfei

    2013-02-01

    Fly ash is a potential alternative to activated carbon for mercury adsorption. The effects of physicochemical properties on the mercury adsorption performance of three fly ash samples were investigated. X-ray fluorescence spectroscopy, X-ray photoelectron spectroscopy, and other methods were used to characterize the samples. Results indicate that mercury adsorption on fly ash is primarily physisorption and chemisorption. High specific surface areas and small pore diameters are beneficial to efficient mercury removal. Incompletely burned carbon is also an important factor for the improvement of mercury removal efficiency, in particular. The C-M bond, which is formed by the reaction of C and Ti, Si and other elements, may improve mercury oxidation. The samples modified with CuBr2, CuCl2 and FeCl3 showed excellent performance for Hg removal, because the chlorine in metal chlorides acts as an oxidant that promotes the conversion of elemental mercury (Hg0) into its oxidized form (Hg2+). Cu2+ and Fe3+ can also promote Hg0 oxidation as catalysts. HCl and O2 promote the adsorption of Hg by modified fly ash, whereas SO2 inhibits the Hg adsorption because of competitive adsorption for active sites. Fly ash samples modified with CuBr2, CuCl2 and FeCl3 are therefore promising materials for controlling mercury emissions. PMID:23596961

  3. Mercury removal from coal combustion flue gas by modified fly ash

    Institute of Scientific and Technical Information of China (English)

    Wenqing Xu; Hairui Wang; Tingyu Zhu; Junyan Kuang; Pengfei Jing

    2013-01-01

    Fly ash is a potential alternative to activated carbon for mercury adsorption.The effects of physicochemical properties on the mercury adsorption performance of three fly ash samples were investigated.X-ray fluorescence spectroscopy,X-ray photoelectron spectroscopy,and other methods were used to characterize the samples.Results indicate that mercury adsorption on fly ash is primarily physisorption and chemisorption.High specific surface areas and small pore diameters are beneficial to efficient mercury removal.Incompletely burned carbon is also an important factor for the improvement of mercury removal efficiency,in particular.The C-M bond,which is formed by the reaction of C and Ti,Si and other elements,may improve mercury oxidation.The samples modified with CuBr2,CuCl2 and FeCl3 showed excellent performance for Hg removal,because the chlorine in metal chlorides acts as an oxidant that promotes the conversion of elemental mercury (Hg0) into its oxidized form (Hg2+).Cu2+ and Fe3+ can also promote Hg0 oxidation as catalysts.HCland O2 promote the adsorption of Hg by modified fly ash,whereas SO2 inhibits the Hg adsorption because of competitive adsorption for active sites.Fly ash samples modified with CuBr2,CuCl2 and FeCl3 are therefore promising materials for controlling mercury emissions.

  4. Effect of temperature on the hydration process and strength development in blends of Portland cement and activated coal gangue or fly ash

    Institute of Scientific and Technical Information of China (English)

    Pei-ming WANG; Xian-ping LIU

    2011-01-01

    This paper describes the results of an investigation into the effect of the variation of curing temperatures between 0 and 60 ℃ on the hydration process,pore structure variation,and compressive strength development of activated coal gangue-cement blend (ACGC).Hardened ACGC pastes cured for hydration periods from 1 to 360 d were examined using the non-evaporable water method,thermal analysis,mercury intrusion porosimetry,and mechanical testing.To evaluate the specific effect of activated coal gangue (ACG) as a supplementary cementing material (SCM),a fly ash-cement blend (FAC) was used as a control.Results show that raising the curing temperature accelerates pozzolanic reactions involving the SCMs,increasing the degree of hydration of the cement blends,and hence increasing the rate of improvement in strength.The effect of curing temperature on FAC is greater than that on ACGC.The pore structure of the hardened cement paste is improved by increasing the curing temperature up to 40 ℃,but when the curing temperature reaches 60 ℃,the changing nature of the pore structure leads to a decrease in strength.The correlation between compressive strength and the degree of hydration and porosity is linear in nature.

  5. The secondary release of mercury in coal fly ash-based flue-gas mercury removal technology.

    Science.gov (United States)

    He, Jingfeng; Duan, Chenlong; Lei, Mingzhe; Zhu, Xuemei

    2016-01-01

    The secondary release of mercury from coal fly ash is a negative by-product from coal-fired power plants, and requires effective control to reduce environmental pollution. Analysing particle size distribution and composition of the coal fly ash produced by different mercury removing technologies indicates that the particles are generally less than 0.5 mm in size and are composed mainly of SiO2, Al2O3, and Fe2O3. The relationships between mercury concentration in the coal fly ash, its particle size, and loss of ignition were studied using different mercury removing approaches. The research indicates that the coal fly ash's mercury levels are significantly higher after injecting activated carbon or brominating activated carbon when compared to regular cooperating-pollution control technology. This is particularly true for particle size ranges of >0.125, 0.075-0.125, and 0.05-0.075 mm. Leaching experiments revealed the secondary release of mercury in discarded coal fly ash. The concentration of mercury in the coal fly ash increases as the quantity of injecting activated carbon or brominating activated carbon increases. The leached concentrations of mercury increase as the particle size of the coal fly ash increases. Therefore, the secondary release of mercury can be controlled by adding suitable activated carbon or brominating activated carbon when disposing of coal fly ash. Adding CaBr2 before coal combustion in the boiler also helps control the secondary release of mercury, by increasing the Hg(2+) concentration in the leachate. This work provides a theoretical foundation for controlling and removing mercury in coal fly ash disposal.

  6. The secondary release of mercury in coal fly ash-based flue-gas mercury removal technology.

    Science.gov (United States)

    He, Jingfeng; Duan, Chenlong; Lei, Mingzhe; Zhu, Xuemei

    2016-01-01

    The secondary release of mercury from coal fly ash is a negative by-product from coal-fired power plants, and requires effective control to reduce environmental pollution. Analysing particle size distribution and composition of the coal fly ash produced by different mercury removing technologies indicates that the particles are generally less than 0.5 mm in size and are composed mainly of SiO2, Al2O3, and Fe2O3. The relationships between mercury concentration in the coal fly ash, its particle size, and loss of ignition were studied using different mercury removing approaches. The research indicates that the coal fly ash's mercury levels are significantly higher after injecting activated carbon or brominating activated carbon when compared to regular cooperating-pollution control technology. This is particularly true for particle size ranges of >0.125, 0.075-0.125, and 0.05-0.075 mm. Leaching experiments revealed the secondary release of mercury in discarded coal fly ash. The concentration of mercury in the coal fly ash increases as the quantity of injecting activated carbon or brominating activated carbon increases. The leached concentrations of mercury increase as the particle size of the coal fly ash increases. Therefore, the secondary release of mercury can be controlled by adding suitable activated carbon or brominating activated carbon when disposing of coal fly ash. Adding CaBr2 before coal combustion in the boiler also helps control the secondary release of mercury, by increasing the Hg(2+) concentration in the leachate. This work provides a theoretical foundation for controlling and removing mercury in coal fly ash disposal. PMID:26121324

  7. Optimising Ambient Setting Bayer Derived Fly Ash Geopolymers

    Directory of Open Access Journals (Sweden)

    Evan Jamieson

    2016-05-01

    Full Text Available The Bayer process utilises high concentrations of caustic and elevated temperature to liberate alumina from bauxite, for the production of aluminium and other chemicals. Within Australia, this process results in 40 million tonnes of mineral residues (Red mud each year. Over the same period, the energy production sector will produce 14 million tonnes of coal combustion products (Fly ash. Both industrial residues require impoundment storage, yet combining some of these components can produce geopolymers, an alternative to cement. Geopolymers derived from Bayer liquor and fly ash have been made successfully with a compressive strength in excess of 40 MPa after oven curing. However, any product from these industries would require large volume applications with robust operational conditions to maximise utilisation. To facilitate potential unconfined large-scale production, Bayer derived fly ash geopolymers have been optimised to achieve ambient curing. Fly ash from two different power stations have been successfully trialled showing the versatility of the Bayer liquor-ash combination for making geopolymers.

  8. Temporal and spatial variations in fly ash quality

    Science.gov (United States)

    Hower, J.C.; Trimble, A.S.; Eble, C.F.

    2001-01-01

    Fly ash quality, both as the amount of petrographically distinguishable carbons and in chemistry, varies in both time and space. Temporal variations are a function of a number of variables. Variables can include variations in the coal blend organic petrography, mineralogy, and chemistry; variations in the pulverization of the coal, both as a function of the coal's Hardgrove grindability index and as a function of the maintenance and settings of the pulverizers; and variations in the operating conditions of the boiler, including changes in the pollution control system. Spatial variation, as an instantaneous measure of fly ash characteristics, should not involve changes in the first two sets of variables listed above. Spatial variations are a function of the gas flow within the boiler and ducts, certain flow conditions leading to a tendency for segregation of the less-dense carbons in one portion of the gas stream. Caution must be applied in sampling fly ash. Samples from a single bin, or series of bins, m ay not be representative of the whole fly ash, providing a biased view of the nature of the material. Further, it is generally not possible to be certain about variation until the analysis of the ash is complete. ?? 2001 Elsevier Science B.V. All rights reserved.

  9. Separation of carbon from fly ash using froth flotation

    Energy Technology Data Exchange (ETDEWEB)

    Walker, A.; Wheelock, T.D. [Iowa State University, Ames, IO (United States). Department of Chemical Engineering

    2006-10-15

    The unburned carbon content of fly ash from two different power stations was greatly reduced in two-stage laboratory flotation tests by employing a collector consisting of nonylphenol and either hexadecane or fuel oil together with methyl isobutinol (MIBC) as a frother. The tailings from the first stage were re-cleaned in the second stage. This method reduced the carbon content of fly ash from an initial level of 25.9% in one case and 16.5% in another case to a final level of 1-2% or less in the tailings while at the same time recovering 95% or more of the carbon in the floated material or concentrate. In most cases from 60 to 75% of the ash was rejected in the tailings. The results support a previous finding that a good collector for oxidized coal is a good collector for unburned carbon in fly ash. Furthermore, the results showed that much less collector was required to achieve a good separation of carbon from fly ash when MIBC was employed in conjunction with the mixed collector.

  10. Durability Studies of Fly Ash Based Geopolymer Concrete

    Directory of Open Access Journals (Sweden)

    Salmabanu Luhar

    2015-08-01

    Full Text Available A detailed study on the durability of geopolymer concrete has been done. Geopolymer concrete is an environment friendly concrete which has lower carbon footprint as compared to that of conventional concrete. In this study, cement has been replaced by fly ash and the properties such as compressive strength, sulphur resistance, acid resistance, water absorption, sorptivity and chloride attack have been studied. Class F fly ash has been used and geopolymer concrete was heat cured for 24 hours under 75◦C. It was observed that use of geopolymer in concrete not only reduces its greenhouse footprint but, also increases its strength and resistivity to harmful acids.

  11. Bronchiolitis obliterans from exposure to incinerator fly ash.

    Science.gov (United States)

    Boswell, R T; McCunney, R J

    1995-07-01

    Inhalation of toxic substances in the workplace can result in a variety of respiratory disorders. One relatively rare sequela of the inhalation of toxic fumes is bronchiolitis obliterans, a condition characterized by fibrosis and narrowing of the small airways. Several substances have been reported to cause bronchiolitis obliterans, including ammonia, chlorine, hydrogen fluoride, hydrogen sulfide, nitrogen dioxide, ozone, phosgene, and other irritant fumes. Little has been reported on the pulmonary effects of fly ash produced by the incineration of coal and oil. We report a case of bronchiolitis obliterans with a component of partially reversible airway obstruction in a 39-year-old male occupationally exposed to incinerator fly ash. PMID:7552470

  12. Sulfate resistance of ordinary Portland cement with fly ash

    OpenAIRE

    Irassar, Edgardo F.; Batic, Oscar R.

    1989-01-01

    Low calcium fly ash has demonstrated to be an effective pozzolan to improve sulfate resistance of ordinary portland cement (type I). In this paper physico-chemical effects that produce this pozzolan in the mortar exposed to sulfate attack are studied. Dilution and dispersion affects are analyzed using mixes of cement with an inert mineral admixture. Mineralogical changes of mortar are studied using X-ray diffraction and the help of scanning electron microscope. The results show that fly...

  13. BRICKS WITH TOTAL REPLACEMENT OF CLAY BY FLY ASH MIXED WITH DIFFERENT MATERIALS

    OpenAIRE

    J.N Akhtar; J. Alam; M N Akhtar

    2011-01-01

    Fly ash is a powdery substance obtained from the dust collectors in the Thermal power plants that use coal as fuel. From the cement point of view the mineralogy of Fly ash is important as it contains 80% - 90% of glass. The impurities in coal-mostly clays, shale’s, limestone & dolomite; they cannot be burned so they turn up as ash. The Fly ash of class C category was used as a raw material to total replacement of clay for making Fly ash bricks. In present study the effect of Fly ash with high...

  14. Beneficial use of fly ash and red mud in geopolymer concrete

    Energy Technology Data Exchange (ETDEWEB)

    Duchesne [Laval Univ., Quebec City, PQ (Canada)

    2009-07-01

    Coal-fired power plants generate millions of tons of fly ash on a yearly basis. Fly ash is a fine particulate aluminosilicate residue mainly composed of spherical micron-sized particles collected from dust collection systems. The management of fly ash is a significant area of concern because only 20 to 30 per cent of the generated fly ash is utilized, primarily in cement and concrete and as filling material, while a much larger portion is deposited in landfills. Red mud is an alkaline industrial residue generated during the Bayer process for alumina production. This paper exhaustively characterized the chemical and mineralogical properties of solid-waste materials. The study investigated the behaviour of geopolymer pastes made using sodium hydroxide and sodium silicate activators. The paper presented the materials and methods as well as results and discussion of x-ray diffraction, scanning electron microscopy, setting time and other early age properties of concrete. It was concluded that fly ash and red mud can be used as the main raw material for the making of geopolymer, a new generation of binder. 10 refs., 1 tab., 6 figs.

  15. MICROSTRUCTURE, MINERALOGY AND PHYSICAL PROPERTIES OF GROUND FLY ASH BASED GEOPOLYMERS

    Directory of Open Access Journals (Sweden)

    Ferenc Madai

    2015-03-01

    Full Text Available This paper is focused on the utilization of deposited fly ash as a main component of geopolymer. After determination of particle size distribution, moisture content, real and bulk density and specific surface area of the raw fly ash, mechanical activation was performed by laboratory scale ball mill. This step is introduced for improving the reactivity of raw material. Then test specimens were produced by geopoliomerisation using a caustic spent liquor (NaOH. Compressive strength was determined on cilindrical specimens. Finally, samples of the ground fly ash based geopolymer specimens were analyzed by X-ray diffraction, optical and scanning electron microscopy. Results prove that geopolymer production with proper strength from the investigated F-type deposited fly ash is possible. The uniaxial compressive strength of obtained composites strongly depends on the fineness of the ground fly ash. XRD results show that comparing the crystalline components for different geopolymer samples, zeolite-A appears and its amount increases gradually from 0T sample till 30T and then decreases for 60T sample. The same trend holds for sodalite type structure phases, however its amount is much lower than for zeolite-A. SEM+EDS investigation revealed that Na-content is elevated in the interstitial fine-grained matrix, especially for the 30T sample when highest strength was observed. Si and Al are abundant mainly in anhedral and spherical grains and in rarely occurring grains resembling some crystal shape.

  16. Degradation of n-butyl xanthate using fly ash as heterogeneous Fenton-like catalyst

    Institute of Scientific and Technical Information of China (English)

    陈绍华; 杜冬云

    2014-01-01

    Heterogeneous Fenton-like process using fly ash as a catalyst was studied to degrade n-butyl xanthate form aqueous solution. The different reaction parameters on the degradation efficiency of the process were investigated. The fly ash/H2O2 catalyst possesses a high oxidation activity for n-butyl xanthate degradation in aqueous solution. It is found that both the dosage of catalyst and initial solution pH significantly affect the n-butyl xanthate conversion efficient. The results indicate that by using 1.176 mmol/L H2O2 and 1.0 g/L fly ash catalyst with mass fraction of 4.14%Fe(III) oxide at pH 3.0, almost 96.90%n-butyl xanthate conversion and over 96.66%COD removal can be achieved within 120 min with heterogeneous catalysis by fly ash. CS2 as an intermediate of n-butyl xanthate oxidation. Finally, it is demonstrated that the fly ash/H2O2 catalytic oxidation process can be an efficient method for the treatment of n-butyl xanthate containing wastewater.

  17. Synergetic use of lignite fly ash and metallurgical converter slag in geopolymer concrete

    Directory of Open Access Journals (Sweden)

    Gábor Mucsi

    2014-08-01

    Full Text Available The application and utilization of the industrial wastes and by-products in the construction industry is a key issue from an environmental and economic point of view. The increased use of lignite has substantially increased the available quantities of lignite fired power plant fly ash, which can be mainly classified as class C fly ash. The utilization of such raw material however has some difficulties. In the present paper lignite fired power station fly ash and metallurgical converter slag were used for the production of geopolymer concrete. The fly ash was used as a geopolymer based binder material, and a converter slag as aggregate, thus created a geopolymer concrete which contains mainly industrial wastes. As preliminary test experimental series were carried out using andesite as aggregate. The optimal aggregate/binder ratio was determined. The effect of the amount of alkaline activator solution in the binder, the aggregate type on the geopolymer concretes’ compressive strength and density was investigated. Furthermore, the physical properties - freeze-thaw resistance and particle size distribution - of the applied aggregates were measured as well. As a result of the experiments it was found that physical properties of the andesite and converter slag aggregate was close. Therefore andesite can be replaced by converter slag in the concrete mixture. Additionally, geopolymer concrete with nearly 20 MPa compressive strength was produced from class C fly ash and converter slag.

  18. Applied technique of the cemented fill with fly ash and fine-sands

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Traditional stabilization of backfilling material is done by using Portland cement. However, the high price of cement forced mining engineers to seek cheaper binding materials. Fly ash, which is the industrial waste from thermal power plant, possess the potential activity of jellification, and can be used in cemented fill as a partial substitute for cement to reduce the fill cost. Tests were done during the past few years in Xinqiao Pyrite Mine and Phoenix Copper Mine to determine the technology parameters and the suitable content of fly ash. Specimens with different cement/fly/ash tailings (sands) ratios were tested to obtain the strength values of the fill mass based on the analyses of both the chemical composition and physical and mechanical properties of fly ash. The compressive strength of specimens with a ratio of 1: 2: 8 (cement to fly ash to tailings)can reach 2 MPa after 90 d curing, totally meeting the requirement of artificial pillar and reducing the fill cost by 20%-30%.

  19. Soil Properties in Coniferous Forest Stands Along a Fly Ash Deposition Gradient in Eastern Germany

    Institute of Scientific and Technical Information of China (English)

    S. KLOSE; F. MAKESCHIN

    2005-01-01

    Physical, chemical, and microbial properties of forest soils subjected to long-term fly ash depositions were analyzed in spruce (Picea abies (L.) Karst.) stands of eastern Germany on three forest sites along an emission gradient of 3 (high input), 6, and 15 km (low input) downwind of a coal-fired power plant. Past emissions resulted in an atypical high mass of mineral fly ash constituents in the organic horizons at the high input site of 128 t ha-1 compared to 58 t ha-1 at the low input site. Magnetic susceptibility measurements proved that the high mineral content of the forest floor was a result of fly ash accumulation in these forest stands. Fly ash deposition in the organic horizons at Site Ⅰ versus Ⅲsignificantly increased the pH values, effective cation exchange capacity, base saturation and, with exception of the L horizon, concentrations of mobile heavy metals Cd, Cr, and Ni, while stocks of organic C generally decreased. A principal component analysis showed that organic C content and base status mainly controlled soil microbial biomass and microbial respiration rates at these sites, while pH and mobile fractions of Cd, Cr, and Ni governed enzyme activities. Additionally,it was hypothesized that long-term fly ash emissions would eventually destabilize forest ecosystems. Therefore, the results of this study could become a useful tool for risk assessment in forest ecosystems that were subjected to past emissions from coal-fired power plants.

  20. Fly ash alkali-activated with NaOH and Ca(OH){sub 2}; Cinzas volantes alcali-ativadas com solucao combinada de NaOH e Ca(OH){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, A.S.; Dal Molin, D.C.C.; Vilela, A.C.F.; Jalali, S.; Gomes, J.C.

    2007-01-15

    The main objective of this work was to evaluate over time the development of the compressive strength of alkali-activated fly ash mortars. A combined solution of NaOH and Ca(OH){sub 2} was used as alkaline activator. The curing of the samples was carried out in two distinct ways. In the first one, samples were kept at 70{sup o}C during the first 12 hours after mixing and at 22{sup o}C afterwards, until the age of testing. Although compressive strengths of about 20 MPa were achieved during the first 24 hours, the strength started to decrease after 7 days. Considering this behaviour, a second method of curing was adopted. The mix proportions were the same as before, however the mortar samples were kept in an oven at 70{sup o}C until the age of testing. In this case, the compressive strength values decreased more significantly and in a shorter period of time, as compared to the results obtained for samples cured using the first method. Complementary studies were performed in order to better understand the observed reduction in compressive strength. Microstructural analyses of the fly ash, before and after the alkali-activation, have been carried out using Scanning Electron Microscopy (SEM) and Energy-Dispersive Spectroscopy (EDS). It was possible to identify three different morphologies in the alkali-activated pastes: one composed by regions with dense aspect; other showing partially solubilised particles of fly ash; and a third showing the formation of products with a needle-like shape. The information provided by the SEM/EDS experiments was not enough to enable the complete understanding of the mechanism of the deleterious reaction that took place among the alkaline activators and the fly ash. 14 refs., 5 tabs.

  1. Optimizing and Characterizing Geopolymers from Ternary Blend of Philippine Coal Fly Ash, Coal Bottom Ash and Rice Hull Ash

    Directory of Open Access Journals (Sweden)

    Martin Ernesto Kalaw

    2016-07-01

    Full Text Available Geopolymers are inorganic polymers formed from the alkaline activation of amorphous alumino-silicate materials resulting in a three-dimensional polymeric network. As a class of materials, it is seen to have the potential of replacing ordinary Portland cement (OPC, which for more than a hundred years has been the binder of choice for structural and building applications. Geopolymers have emerged as a sustainable option vis-à-vis OPC for three reasons: (1 their technical properties are comparable if not better; (2 they can be produced from industrial wastes; and (3 within reasonable constraints, their production requires less energy and emits significantly less CO2. In the Philippines, the use of coal ash, as the alumina- and silica- rich geopolymer precursor, is being considered as one of the options for sustainable management of coal ash generation from coal-fired power plants. However, most geopolymer mixes (and the prevalent blended OPC use only coal fly ash. The coal bottom ash, having very few applications, remains relegated to dumpsites. Rice hull ash, from biomass-fired plants, is another silica-rich geopolymer precursor material from another significantly produced waste in the country with only minimal utilization. In this study, geopolymer samples were formed from the mixture of coal ash, using both coal fly ash (CFA and coal bottom ash (CBA, and rice hull ash (RHA. The raw materials used for the geopolymerization process were characterized using X-ray fluorescence spectroscopy (XRF for elemental and X-ray diffraction (XRD for mineralogical composition. The raw materials’ thermal stability and loss on ignition (LOI were determined using thermogravimetric analysis (TGA and reactivity via dissolution tests and inductively-coupled plasma mass spectrometry (ICP analysis. The mechanical, thermal and microstructural properties of the geopolymers formed were analyzed using compression tests, Fourier transform infra-red spectroscopy (FTIR

  2. Natural radioactivity of coal and fly ash at the Nikola Tesla B TPP

    OpenAIRE

    Kisić Dragica M.; Miletić Saša R.; Radonjić Vladimir D.; Radanović Sanja B.; Filipovic Jelena Z.; Gržetić Ivan A.

    2013-01-01

    Serbian thermal power plants (TPPs) produce siliceous fly ash from lignite in the quantity of approximately 6 million tons per year. The potential market for the use of fly ash is operational, but for the time being, only used by cement producers. Fly ash radioactivity could be one of the major points of concern when larger use of fly ash is planned, particularly in the Serbian construction industry. Radioactivity measurements have been conducted regularly ...

  3. Restoration of Ecosystems Destroyed by the Fly Ash Dump Using Different Plant Species

    OpenAIRE

    Florica Morariu; Smaranda Mâșu; Benoni Lixandru; Dumitru Popescu

    2013-01-01

    The leguminous plants was studied at experimental variants on fly ash dump: sown species of Onobrichys viciifolia and invasive colonies of Bird's-foot Trefoil (Lotus corniculatus), and yellow sweet (Melilotus officinalis). Six experimental variants were studied in three replicates each: untreated fly ash, fly ash amended with unmodified/modified volcanic rock and fly ash treated with unmodified/modified volcanic rock (indigenous volcanic tuff) mixed with organic fertilizer, anaerobically stab...

  4. Experimental Study on Durability Improvement of Fly Ash Concrete with Durability Improving Admixture

    OpenAIRE

    Quan, Hong-zhu; Kasami, Hideo

    2014-01-01

    In order to improve the durability of fly ash concrete, a series of experimental studies are carried out, where durability improving admixture is used to reduce drying shrinkage and improve freezing-thawing resistance. The effects of durability improving admixture, air content, water-binder ratio, and fly ash replacement ratio on the performance of fly ash concrete are discussed in this paper. The results show that by using durability improving admixture in nonair-entraining fly ash concrete,...

  5. Leaching Behavior of Fly Ashes from Power Plants

    Institute of Scientific and Technical Information of China (English)

    LIU Guijian; GAO Lianfen; ZHENG Liugen; ZHANG Haoyuan; PENG Zicheng

    2004-01-01

    The Yanzhou mine district, located in southwestern Shandong Province, is about 1300 km2 with more than 8×109 tons of proved coal reserves and there are 10 big power plants in this area. A large amount of coal ashes, which are regarded as waste materials, have been stockpiled in the area and have influenced the environment of the mine district. In this paper, analysis of fly ash samples from three power plants is carried out, the enrichment and concentration of trace elements, Pb, Zn, Cu and As, in coal ashes are analyzed, and petrological and mineralogical characteristics and chemical compositions of coal ashes are studied. The aim of this work is to provide basic scientific data for utilization of ashes and reduction of environmental pollutions.

  6. Phenolic acids as bioindicators of fly ash deposit revegetation

    Energy Technology Data Exchange (ETDEWEB)

    L. Djurdjevic; M. Mitrovic; P. Pavlovic; G. Gajic; O. Kostic [Institute for Biological Research ' Sinisa Stankovic,' Belgrade (Serbia and Montenegro). Department of Ecology

    2006-05-15

    The floristic composition, the abundance, and the cover of pioneer plant species of spontaneously formed plant communities and the content of total phenolics and phenolic acids, as humus constituents, of an ash deposit after 7 years of recultivation were studied. The restoration of both the soil and the vegetation on the ash deposits of the 'Nikola Tesla-A' thermoelectric power plant in Obrenovac (Serbia) is an extremely slow process. Unfavorable physical and chemical characteristics, the toxicity of fly ash, and extreme microclimatic conditions prevented the development of compact plant cover. The abundance and cover of plants increased from the central part of the deposit towards its edges. Festuca rubra L., Crepis setosa Hall., Erigeron canadensis L., Cirsium arvense (L.) Scop., Calamagrostis epigeios (L.) Roth., and Tamarix gallica L. were the most abundant species, thus giving the highest cover. Humus generated during the decomposition process of plant remains represents a completely new product absent in the ash as the starting material. The amount of total phenolics and phenolic acids in fly ash increased from the center of the deposit towards its edges in correlation with the increase in plant abundance and cover. The presence of phenolic acids indicates the ongoing process of humus formation in the ash, in which the most abundant pioneer plants of spontaneously formed plant communities play the main role. Phenolic compounds can serve as reliable bioindicators in an assessment of the success of the recultivation process of thermoelectric power plants' ash deposits.

  7. Characterization of municipal solid waste incineration fly ash before and after electrodialytic treatment

    DEFF Research Database (Denmark)

    Pedersen, Anne Juul; Gardner, Kevin H.

    2003-01-01

    Municipal solid waste incineration (MSWI) fly ash, which has been treated electrodialytically for the removal of heavy metals, may have changed characteristics compared to untreated fly ash. In this study, MSWI fly ash was characterized with respect to leaching properties (pH static leaching...

  8. Fly Ash Admixture and its Influence on Alitic Type Cement Concrete Permeability

    OpenAIRE

    Rujanu, Mircea; Rujanu, Bogdan

    2012-01-01

    Experimental and theoretical studies pointed that adding fly ash in concrete composition, could favour its impermeability characteristic improvement. It is known, also, that fly ash admixture achieves cement dosage reduction, so that concrete will be cheaper, and in this conditions it is important to analyse fly ash admixture influence on impermeability degree, too.

  9. Contribution of aluminas and aluminosilicates to the formation of PCDD/Fs on fly ashes.

    Science.gov (United States)

    Potter, Phillip M; Dellinger, Barry; Lomnicki, Slawomir M

    2016-02-01

    Chlorinated aromatics undergo surface-mediated reactions with metal oxides to form Environmentally Persistent Free Radicals (EPFRs) which can further react to produce polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Previous work using laboratory-made fly ash surrogates composed of transition metal oxides deposited on silica powder has confirmed their ability to mimic fly ash in the production of PCDD/Fs. However, little is known about the propensity of aluminas and aluminosilicates, other components of fly ash, to form PCDD/Fs. A fly ash sample containing both alumina and mullite, an aluminosilicate, was tested for PCDD/F formation ability and compared to PCDD/F yields from the thermal degradation of 2-monochlorophenol (2-MCP) precursor over γ-alumina, α-alumina, and mullite. A packed-bed flow reactor was used to investigate the thermal degradation of 2-MCP over the various catalysts at 200-600 °C. Fly ash gave similar PCDD/F yields to surrogates made with similar transition metal content. γ-alumina, which is thermodynamically unfavorable, was very catalytically active and gave low PCDD/F yields despite a high destruction of 2-MCP. Mullite and α-alumina, the thermodynamically favorable form of alumina, yielded higher concentrations of dioxins and products with a higher degree of chlorine substitution than γ-alumina. The data suggest that certain aluminas and aluminosilicates, commonly found in fly ash, are active catalytic surfaces in the formation of PCDD/Fs in the post-flame cool zones of combustion systems and should be considered as additional catalytic surfaces active in the process. PMID:26615490

  10. Fly ash porous material using geopolymerization process for high temperature exposure.

    Science.gov (United States)

    Abdullah, Mohd Mustafa Al Bakri; Jamaludin, Liyana; Hussin, Kamarudin; Bnhussain, Mohamed; Ghazali, Che Mohd Ruzaidi; Ahmad, Mohd Izzat

    2012-01-01

    This paper presents the results of a study on the effect of temperature on geopolymers manufactured using pozzolanic materials (fly ash). In this paper, we report on our investigation of the performance of porous geopolymers made with fly ash after exposure to temperatures from 600 °C up to 1000 °C. The research methodology consisted of pozzolanic materials (fly ash) synthesized with a mixture of sodium hydroxide and sodium silicate solution as an alkaline activator. Foaming agent solution was added to geopolymer paste. The geopolymer paste samples were cured at 60 °C for one day and the geopolymers samples were sintered from 600 °C to 1000 °C to evaluate strength loss due to thermal damage. We also studied their phase formation and microstructure. The heated geopolymers samples were tested by compressive strength after three days. The results showed that the porous geopolymers exhibited strength increases after temperature exposure.

  11. Vapor-phase elemental mercury adsorption by residual carbon separated from fly ash

    Institute of Scientific and Technical Information of China (English)

    WANG Li-gang; CHEN Chang-he; Kruse H.Kolker

    2005-01-01

    The adsorption capacity for vapor-phase elemental mercury(Hg0 ) of residual carbon separated from fly ash was studied in an attempt for the control of elemental mercury emissions from combustion processes. At Iow mercury concentrations ( < 200 μg/m3),unburned carbon had higher adsorption capacity than commercial activated carbon. The adsorbality of unburned carbon was also found to be source dependent. Isotherms of FS carbon(separated from fly ash of a power plant of Shishi in Fujian Province) were similar to those classified as type Ⅱ. Isotherms of XJ carbon (separated from fly ash of a power plant of Jingcheng in Shanxi Province) were more like those classified as type Ⅲ. Due to the relatively Iow production costs, these residual carbons would likely be considerably more costeffective for the full-scale removal of mercury from combustion flue gases than other technology.

  12. Use of olive biomass fly ash in the preparation of environmentally friendly mortars.

    Science.gov (United States)

    Cruz-Yusta, Manuel; Mármol, Isabel; Morales, Julián; Sánchez, Luis

    2011-08-15

    The incorporation of fly ash from olive biomass (FAOB) combustion in cogeneration plants into cement based mortars was explored by analyzing the chemical composition, mineralogical phases, particle size, morphology, and IR spectra of the resulting material. Pozzolanic activity was detected and found to be related with the presence of calcium aluminum silicates phases. The preparation of new olive biomass fly ash content mortars is effective by replacing either CaCO(3) filler or cement with FAOB. In fact, up to 10% of cement can be replaced without detracting from the mechanical properties of a mortar. This can provide an alternative way to manage the olive biomass fly ash as waste produced in thermal plants and reduce cement consumption in the building industry, and hence an economically and environmentally attractive choice.

  13. Compressive strength and hydrolytic stability of fly ash based geopolymers

    Directory of Open Access Journals (Sweden)

    Nikolić Irena

    2013-01-01

    Full Text Available The process of geopolymerization involves the reaction of solid aluminosilicate materials with highly alkaline silicate solution yielding an aluminosilicate inorganic polymer named geopolymer, which may be successfully applied in civil engineering as a replacement for cement. In this paper we have investigated the influence of synthesis parameters: solid to liquid ratio, NaOH concentration and the ratio of Na2SiO3/NaOH, on the mechanical properties and hydrolytic stability of fly ash based geopolymers in distilled water, sea water and simulated acid rain. The highest value of compressive strength was obtained using 10 mol dm-3 NaOH and at the Na2SiO3/NaOH ratio of 1.5. Moreover, the results have shown that mechanical properties of fly ash based geopolymers are in correlation with their hydrolytic stability. Factors that increase the compressive strength also increase the hydrolytic stability of fly ash based geopolymers. The best hydrolytic stability of fly ash based geopolymers was shown in sea water while the lowest stability was recorded in simulated acid rain. [Projekat Ministarstva nauke Republike Srbije, br. 172054 i Nanotechnology and Functional Materials Center, funded by the European FP7 project No. 245916

  14. High filler concrete using fly ash: Chloride penetration and microstructure

    NARCIS (Netherlands)

    Valcke, S.L.A.; Polder, R.B.; Nijland, T.G.; Leegwater, G.A.; Visser, J.H.M.; Bigaj-van Vliet, A.J.

    2012-01-01

    Most high filler concrete studies are based on relatively high contents of powder (cement + filler) (>400 kg m-3). This paper aims to increase the total fly ash content relative to the clinker content, while simultaneously minimizing the total powder content in the concrete to values lower than 300

  15. Use of fly ash in road foundation beds

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Arango, I.; Hacar, F.

    1988-01-01

    Fly-ash can be successfully used in the foundation layers of roads. This article presents a complete study of the possible applications of this material and of its use in road-building, describing the planning, implementation, tests and conclusions.

  16. Separation of ultrafine particles from class F fly ashes

    Directory of Open Access Journals (Sweden)

    Acar Ilker

    2016-01-01

    Full Text Available In this study, ultrafine particles were recovered from Çatalağzı (CFA and Sugözü (SFA thermal power plant fly ashes using a specific hydraulic classification technology. Since fly ashes have a high tendency to be flocculated in water, settling experiments were first designed to determine the more effective dispersant and the optimum dosage. Two different types of the superplasticizers (SP polymers based on sulphonate (NSF, Disal and carboxylate (Glenium 7500 were used as the dispersing agents in these settling experiments. Hydraulic classification experiments were then conducted to separate ultrafine fractions from the fly ash samples on the basis of the settling experiments. According to the settling experiments, better results were achieved with the use of Disal for both CFA and SFA. The classification experiments showed that the overflow products with average particle sizes of 5.2 μm for CFA and 4.4 μm for SFA were separated from the respective as-received samples with acceptable yields and high enough recoveries of -5 μm (ultrafine particles. Overall results pointed out that the hydraulic classification technology used provided promising results in the ultrafine particle separations from the fly ash samples.

  17. Separating Performance of Fly Ash in Water Media

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The stress state and floating-sinking reqularity of various particles in fly ash in water were analyzed. Theformula for calculating the floating-sinking rate was given. And the formula for calculating the magnetic forceneeded to separate magnetic beads from magnetic separator was also obtained.

  18. Ultrasonic studies of fly ash/polyurea composites

    Science.gov (United States)

    Qiao, Jing; Amirkhizi, Alireza V.; Nemat-Nasser, Sia; Wu, Gaohui

    2013-04-01

    Due to its excellent thermo-mechanical properties, polyurea is attracting more and more attention in blast-mitigating applications. In order to enhance its capability of blast-induced stress-wave management, we seek to develop polyurea-based composites in this work. Fly ash which consists of hollow particles with porous shell and low apparent density was chosen as filler and a series of fly ash/polyurea composites with various fly ash volume fractions were fabricated. The dynamic mechanical behavior of the composites was determined by a personal computer (PC) based ultrasonic system in the 0.5-2MHz frequency range between -60°C to 30°C temperatures. Velocity and attenuation of both longitudinal and shear ultrasonic waves were measured. The complex longitudinal and shear moduli were then computed from these measurements. Combining these results provided an estimate of the complex bulk and Young's moduli of the fly ash/polyurea composites at high frequencies. These results will be presented and compared with those of pure polyurea elastomer.

  19. Investigation on autoclaved fly-ash brick production technique

    Institute of Scientific and Technical Information of China (English)

    ZouJi

    2005-01-01

    The article through analyzing the raw material properties and the production process of the autociaved fly-ash building products, and every kinds of influencing factor on products quantity ,investigated the optimum parameter, such as optimum steam curingtechnique level, has got good expansion meaning.system etc, and indicated that the production line has high technique level, has got good expansion meaning.

  20. High filler concrete using fly ash. Chloride penetration and microstructure

    NARCIS (Netherlands)

    Valcke, S.L.A.; Polder, R.B.; Nijland, T.G.; Leegwater, G.A.; Visser, J.H.M.; Bigaj-van Vliet, A.J.

    2012-01-01

    Most high filler concrete studies are based on relatively high contents of powder (cement + filler) (>400 kg m-3). This paper aims to increase the total fly ash content relative to the clinker content, while simultaneously minimizing the total powder content in the concrete to values lower than 300

  1. Aluminum recovery from coal fly ash by high temperature chlorination

    Energy Technology Data Exchange (ETDEWEB)

    Wijatno, H.

    1977-10-01

    A study of aluminum recovery from power plant fly ash by high temperature chlorination was undertaken to demonstrate that fly ash could be a potential source of aluminum, iron and possibly silicon. Magnetic separation of the iron oxide served as a first step to alleviate the iron contamination problem. However, the agglomeration of some iron oxide with alumina and silica made it difficult to completely separate the iron from the fly ash. Further iron separation was achieved by chlorinating the nonmagnetic ash fraction at 550/sup 0/C for 30 minutes. This reduced the iron oxide content to less than 4 percent by weight. Chlorine flow rates affected the reaction rate much more drastically than temperatures. This suggested that diffusion was the major rate-controlling step. Besides Fe/sub 2/O/sub 3/, Al/sub 2/O/sub 3/ and SiO/sub 2/, other oxides such as CaO, K/sub 2/O, Na/sub 2/O and MgO might have complicated the alumina recovery by forming individual chlorides or complexes. Investigating methods for separating more Fe/sub 2/O/sub 3/, and possibly CaO, K/sub 2/O, Na/sub 2/O and MgO from the nonmagnetic ash fraction before chlorinating it is highly recommended.

  2. Recycling Jorf Lasfar fly ash as an additive to cement

    Directory of Open Access Journals (Sweden)

    Hamadi A

    2012-09-01

    Full Text Available Recycling fly ash is a good example of valorization of waste. It gives a solution the environmental problem by avoiding land filling, and reducing CO2 emission in the atmosphere. In this work we studied the physical-chemical characteristics of Jorf Lasfar fly ash. The parameters investigated were particle size, density, specific surface Blaine, chemical and mineralogical compositions. The techniques used are scanning electronic microscope (SEM, transmission electronic microscope (TEM, X-rays fluorescence (XRF, X-rays diffraction (XRD and atomic spectrometry emission coupled with inductive plasma ICP. We also conducted a study on the mechanical behavior of type CPJ45 cements produced from a combined grinding of clinker, limestone and gypsum. The substitution of a portion of the clinker by different percentages of fly ash was conducted. We noticed that the compression and bending resistances for these mixtures went through a maximum at 28 days with the addition of 7% (by mass of ash. This result showed that the mineral and chemical compositions of this ash conferred a Pozzoulanic power to the cement studied.

  3. Recovery of gallium and vanadium from gasification fly ash

    International Nuclear Information System (INIS)

    The Puertollano Integrated Coal Gasification Combined Cycle (IGCC) Power Plant (Spain) fly ash is characterized by a relatively high content of Ga and V, which occurs mainly as Ga2O3 and as Ga3+ and V3+substituting for Al3+ in the Al-Si fly ash glass matrix. Investigations focused on evaluating the potential recovery of Ga and V from these fly ashes. Several NaOH based extraction tests were performed on the IGCC fly ash, at different temperatures, NaOH/fly ash (NaOH/FA) ratios, NaOH concentrations and extraction times. The optimal Ga extraction conditions was determined as 25 deg. C, NaOH 0.7-1 M, NaOH/FA ratio of 5 L/kg and 6 h, attaining Ga extraction yields of 60-86%, equivalent to 197-275 mg of Ga/kg of fly ash. Re-circulation of leachates increased initial Ga concentrations (25-38 mg/L) to 188-215 mg/L, while reducing both content of impurities and NaOH consumption. Carbonation of concentrated Ga leachate demonstrated that 99% of the bulk Ga content in the leachate precipitates at pH 7.4. At pH 10.5 significant proportions of impurities, mainly Al (91%), co-precipitate while >98% of the bulk Ga remains in solution. A second carbonation of the remaining solution (at pH 7.5) recovers the 98.8% of the bulk Ga. Re-dissolution (at pH 0) of the precipitate increases Ga purity from 7 to 30%, this being a suitable Ga end product for further purification by electrolysis. This method produces higher recovery efficiency than currently applied for Ga on an industrial scale. In contrast, low V extraction yields (<64%) were obtained even when using extreme alkaline extraction conditions, which given the current marked price of this element, limits considerably the feasibility of V recovery from IGCC fly ash

  4. Selenium speciation and cycling in fly ash ponds

    Energy Technology Data Exchange (ETDEWEB)

    Wallschlager, D. [Frontier Geosciences, Seattle, WA (United States); Carlton, R.B. [Electric Power Research Inst., Palo Alto, CA (United States)

    2001-07-01

    Selenium (Se) is becoming a major element of concern in many aquatic ecosystems because of its ecotoxicity for fish and waterfowl. Elevated Se concentrations in impacted water bodies may be due to both geogenic and anthropogenic sources. Several coal-fired power plants face Se problems since they burn certain types of coal which are geologically-enriched in selenium. The Se pool is volatilized during combustion and ends up in one or two waste streams, fly ash and scrubber water. Both waste streams usually end up in man-made or natural aquatic ecosystems and may create an ecotoxicological risk due to the Se content. Only a few coal-fired power plants currently use wet scrubber technology to remove sulfur from their flue gas, which also results in a selenium bearing waste water stream. Most power plants have electrostatic precipitators to remove particulates from the flue gas stream. Fly ash is the solid residue from this process. It is often enriched in Se, arsenic and chromium. Fly ash is typically stored under water in fly ash ponds. Efforts are being made to manage the biochemistry of selenium in fly ash ponds in a way that promotes fixation in the pond sediments, reducing the mobilization into water and minimizing the risk to wildlife. This paper reported the results of a pilot study in which Se contaminated water of a settling pond was draining a dry fly ash disposal site. The authors examined Se speciation in the fly ash pond waters and sediments to comprehend the biogeochemical Se cycling in the system. Total and dissolved Se in the waters and sediment pore waters were determined by hydride generation-atomic fluorescence spectrometry (HG-AFS). Ion chromatography coupled with HG-AFS was used to determine dissolved Se speciation in waters and pore waters. Se associated with iron and manganese hydroxide was also determined by comparing extractions with two different reductants, hydroxyl ammonium hydro chloride and sodium dithionite. Results indicated that

  5. Heated fly ash/hydrated lime slurries for SO[sub 2] removal in spray dryer absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Sanders, J.F.; Keener, T.C.; Wang, J. (Univ. of Cincinnati, OH (United States). Dept. of Civil and Environmental Engineering)

    1995-01-01

    Coal fly ashes have been slurried with quicklime at elevated temperatures to determine their reactivity with SO[sub 2] in a minipilot spray dryer. Bench-scale experimental results indicate that this hydration process greatly increases the total surface area of the solids. Minipilot-scale spray dryer tests reveal that the slurry reaction step can significantly increase calcium utilization and SO[sub 2] removal of these fly ash/quicklime sorbents, depending on the type of fly ash used. One type of fly ash showed considerably better reactivity in the spray dryer tests. This enhancement is considered due to the presence of calcium silica hydrate material formed from the reaction between calcium and the alumina silicate found in the fly ashes and the difference in reactivity due to the type of calcium silica hydrate material formed. The benefit, however, decreases with the calcium feed rate. Pozzolanic strength tests were performed on the fly ashes used, and the measured unconfined compressive strengths followed the reactivity results in the spray dryer; the most reactive fly ash possessed the highest pozzolanic activity.

  6. The complex impedance response of fly-ash cements revisited

    Energy Technology Data Exchange (ETDEWEB)

    W.J. McCarter; G. Starrs; T.M. Chrisp [Heriot-Watt University, Edinburgh (United Kingdom). School of the Built Environment

    2004-10-01

    It has been previously reported that when a low-lime fly ash is introduced as a cementitious component, there are significant changes in the electrical response of the system, most notably, an enhancement in dielectric constant and the emergence of a plateau region in the complex plane. The changes in electrical behaviour were attributed to the spherical nature of the fly-ash particle, resulting in an enhancement in the double-layer polarization effects on the particle surface. In this paper, data are presented for three low-lime ashes, each displaying differences in their electrical behaviour. Through a systematic series of tests, a new interpretation for the origin of the characteristic electrical response is presented.

  7. Reduction in CO{sub 2} emission from normal and saline soils amended with coal fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Sang-Sun; Choi, Woo-Jung; Lee, Kwang-Seung [Chonnam National Univ., Gwangju (Korea, Republic of). Dept. of Rural and Bio-Systems Engineering; Ro, Hee-Myong [Seoul National Univ., Seoul (Korea, Republic of). Dept. of Agricultural Biotechnology

    2012-10-15

    Fly ash can reduce CO{sub 2} emission from soils via biochemical (i.e., inhibition of microbial activity) and physicochemical (i.e., carbonation) mechanisms. This study investigated the effects of fly ash amendment on biochemical and physicochemical reduction in CO{sub 2} emission from normal and saline soils. The physicochemical mechanisms of reduction in CO{sub 2} emission by fly ash were estimated in a batch experiment with carbonate solution as a CO{sub 2} source by the scanning electron microscope (SEM) and inductively coupled plasma analyses. Biochemical mechanisms of reduction in CO{sub 2} emission by fly ash were investigated in a 3-day laboratory incubation experiment with normal and saline soils in the absence and presence of fly ash. Finally, the effects of fly ash amendment at a variety rate from 2 to 15 % (w/w) on CO{sub 2} emission from normal and saline soils in the presence of additional organic carbon source (glucose) were investigated through a 15-day laboratory incubation study. In the batch experiment with carbonate solution, both the SEM image of fly ash and changes in soluble Ca and Mg concentrations during reaction with carbonate suggested that the formation of CaCO{sub 3} and MgCO{sub 3} via carbonation was the principal physicochemical mechanism of carbonate removal by fly ash. In the 3-day incubation study conducted to examine biochemical mechanisms of reduction in CO{sub 2} emission by fly ash, microbial respiration of saline soil was inhibited (P < 0.05) by fly ash due to high pH, salinity, and boron concentration of fly ash; meanwhile, for normal soil, there was no inhibitory effect of fly ash on microbial respiration. In the 15-day incubation with glucose, fly ash application at a variety rates from 2 to 15 % (w/w) reduced CO{sub 2} emission by 3.6 to 21.4 % for normal and by 19.8 to 30.3 % for saline soil compared to the control without fly ash. For saline soil, the reduction in CO{sub 2} emission was attributed primarily to

  8. Microstructural and compositional change of NaOH-activated high calcium fly ash by incorporating Na-aluminate and co-existence of geopolymeric gel and C–S–H(I)

    KAUST Repository

    Oh, Jae Eun

    2012-05-01

    This study explores the reaction products of alkali-activated Class C fly ash-based aluminosilicate samples by means of high-resolution synchrotron X-ray diffraction (HSXRD), scanning electron microscope (SEM), and compressive strength tests to investigate how the readily available aluminum affects the reaction. Class C fly ash-based aluminosilicate raw materials were prepared by incorporating Na-aluminate into the original fly ashes, then alkali-activated by 10 M NaOH solution. Incorporating Na-aluminate reduced the compressive strength of samples, with the reduction magnitude relatively constant regardless of length of curing period. The HSXRD provides evidence of the co-existence of C-S-H with geopolymeric gels and strongly suggests that the C-S-H formed in the current system is C-S-H(I). The back-scattered electron images suggest that the C-S-H(I) phase exists as small grains in a finely intermixed form with geopolymeric gels. Despite providing extra source of aluminum, adding Na-aluminate to the mixes did not decrease the Si/Al ratio of the geopolymeric gel. © 2012 Elsevier Ltd.

  9. Influence of fly ash fineness on strength, drying shrinkage and sulfate resistance of blended cement mortar

    Energy Technology Data Exchange (ETDEWEB)

    P. Chindaprasirt; S. Homwuttiwong; V. Sirivivatnanon [Khon Kaen University, Khon Kaen (Thailand). Department of Civil Engineering

    2004-07-01

    In this paper, the influence of fineness of fly ash on water demand and some of the properties of hardened mortar are examined. In addition to the original fly ash (OFA), five different fineness values of fly ash were obtained by sieving and by using an air separator. Two sieves, Nos. 200 and 325, were used to obtain two lots of graded fine fly ash. For the classification using air separator, the OFA was separated into fine, medium and coarse portions. The fly ash dosage of 40% by weight of binder was used throughout the experiment. From the tests, it was found that the compressive strength of mortar depended on the fineness of fly ash. The strength of mortar containing fine fly ash was better than that of OFA mortar at all ages with the very fine fly ash giving the highest strength. The use of all fly ashes resulted in significant improvement in drying shrinkage with the coarse fly ash showing the least improvement owing primarily to the high water to binder ratio (W/B) of the mix. Significant improvement of resistance to sulfate expansion was obtained for all fineness values except for the coarse fly ash where greater expansion was observed. The resistance to sulfuric acid attack was also improved with the incorporation of all fly ashes. In this case the coarse fly ash gave the best performance with the lowest rate of the weight loss owing probably to the better bonding of the coarse fly ash particles to the cement matrix and less hydration products. It is suggested that the fine fly ash is more reactive and its use resulted in a denser cement matrix and better mechanical properties of mortar.

  10. Heavy metals distribution in fly ash from gangue power plant

    Institute of Scientific and Technical Information of China (English)

    ZHOU Guang-zhu; WANG Cui-zhen; HAN Zuo-zhen; YANG Hai-feng; WAN Rui

    2007-01-01

    To make assessment on its environmental security,fly ash samples were collected from the gangue power plant.Total content of heavy metals in sieved fly ash were analytically determined.We also carried out Tessier extractive experiments to check the chemical species of heavy metals.Experiment results show that the content of Cu,Zn,Pb and Cd ascend when particle size is smaller.Cu,Zn,Pb and Cd obviously enrich in particulate fly ash.The chemical species of heavy metal distribution ranking sequence generally is residual>organic combinative>Fe-Mn oxide combinative>carbonate combinative>ion-exchangeable.Lead's amiable-move species were high in proportion,amounted to 35%.Total content of Cadmium is at low level.but its ion-exchangeable species is relatively high in proportion.Nickel and zinc is mainly distributed in residue.CU is mainly distributed in residue and Organic combinative form.The content of manganese is relatively high in fly ash,and the carbonate combinative iron-manganese oxide combinative species are main chemical form.Cr is mainly distributed in residue.and its other chemical species are at low level.Compared with the soil background value of study area and Shandong Province,the content of Cu,Ni,Zn,Mn and Cr in fly ash of gangue power plant is lower.While contents of Pb and Cd were higher than background value,and amiable-move species is relatively high in proportion.They are more apt to cause heavy metal pollution.

  11. Elastic properties of fly ash-stabilized mixes

    Directory of Open Access Journals (Sweden)

    Sanja Dimter

    2015-12-01

    Full Text Available Stabilized mixes are used in the construction of bearing layers in asphalt and concrete pavement structures. Two nondestructive methods: resonant frequency method and ultrasonic pulse velocity method, were used for estimation of elastic properties of fly ash–stabilized mixes. Stabilized mixes were designed containing sand from the river Drava and binder composed of different share of cement and fly ash. The aim of the research was to analyze the relationship between the dynamic modulus of elasticity determined by different nondestructive methods. Data showed that average value of elasticity modulus obtained by the ultrasound velocity method is lower than the values of elasticity modulus obtained by resonant frequency method. For further analysis and enhanced discussion of elastic properties of fly ash stabilized mixes, see Dimter et al. [1].

  12. Synthesis and characterization of novel solid base catalyst from fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Deepti Jain; Chitralekha Khatri; Ashu Rani [University of Kota, Rajasthan (India). Department of Pure and Applied Chemistry

    2011-06-15

    A new type of solid base catalyst was synthesized by chemical and thermal activation of fly ash, collected from Thermal Super Power Station situated in Kota, Rajasthan, India. The chemical activation was carried out by 50 wt.% NaOH followed by thermal activation at 450{sup o}C. The modified physiochemical property of solid base fly ash (SBFA) was determined by X-ray diffraction, FT-IR spectroscopy, Scanning Electron Microscopy, N{sub 2} adsorption-desorption studies and Flame Atomic Absorption Spectrophotometry. The results reveal that the catalyst is nano-crystalline in nature with crystallite size 11 nm and particle size in the range 840 nm to 6.95 {mu}m. The surface basicity and therefore, catalytic activity in SBFA was originated by increased hydroxyl content as compared to fly ash, suggesting that the catalyst possess higher surface active sites. The basicity of the catalyst was measured by liquid phase, solvent free, single step condensation of benzaldehyde with cyclohexanone giving higher conversion ({gt}70%) and selectivity ({gt}80%) of desired product a,a'-dibenzylidenecyclohexanone. This excellent conversion shows that the catalyst has sufficient basic sites both on the surface and in the bulk, responsible for the catalytic activity. Furthermore, this catalyst may replace conventional environmentally hazardous homogeneous liquid bases making an ecofriendly, solvent free, solid base catalyzed process. The application of fly ash to synthesize a solid base catalyst finds a noble way to utilize this abundant waste material. 26 refs., 5 figs., 2 tabs.

  13. Mössbauer characterization of feed coal, ash and fly ash from a thermal power plant

    International Nuclear Information System (INIS)

    The aim of this work was apply 57Fe Transmission Mössbauer Spectroscopy at room temperature in order to study the occurrence of iron-containing mineral phases in: 1) feed coal; 2) coal ash, obtained in different stages of the ASTM D3174 standard method; and 3) fly ash, produced when coal is burned in the TERMOPAIPA IV thermal power plant localized in Boyacá, Colombia. According to obtained results, we can conclude the occurrence of pyrite and jarosite in the feed coal; Fe2+ and Fe3+ crystalline paramagnetic phases, superparamagnetic hematite and hematite in coal ash; Fe2+ and Fe3+ noncrystalline and crystalline phases, magnetite and hematite in fly ash. Precisely, for a basic understanding, this work discusses some the possible transformations that take place during coal combustion

  14. Development of Fly Ash Derived Sorbents to Capture CO2 from Flue Gas of Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    M. Mercedes Maroto-Valer; John M. Andresen; Yinzhi Zhang; Zhe Lu

    2003-12-31

    This research program focused on the development of fly ash derived sorbents to capture CO{sub 2} from power plant flue gas emissions. The fly ash derived sorbents developed represent an affordable alternative to existing methods using specialized activated carbons and molecular sieves, that tend to be very expensive and hinder the viability of the CO{sub 2} sorption process due to economic constraints. Under Task 1 'Procurement and characterization of a suite of fly ashes', 10 fly ash samples, named FAS-1 to -10, were collected from different combustors with different feedstocks, including bituminous coal, PRB coal and biomass. These samples presented a wide range of LOI value from 0.66-84.0%, and different burn-off profiles. The samples also spanned a wide range of total specific surface area and pore volume. These variations reflect the difference in the feedstock, types of combustors, collection hopper, and the beneficiation technologies the different fly ashes underwent. Under Task 2 'Preparation of fly ash derived sorbents', the fly ash samples were activated by steam. Nitrogen adsorption isotherms were used to characterize the resultant activated samples. The cost-saving one-step activation process applied was successfully used to increase the surface area and pore volume of all the fly ash samples. The activated samples present very different surface areas and pore volumes due to the range in physical and chemical properties of their precursors. Furthermore, one activated fly ash sample, FAS-4, was loaded with amine-containing chemicals (MEA, DEA, AMP, and MDEA). The impregnation significantly decreased the surface area and pore volume of the parent activated fly ash sample. Under Task 3 'Capture of CO{sub 2} by fly ash derived sorbents', sample FAS-10 and its deashed counterpart before and after impregnation of chemical PEI were used for the CO{sub 2} adsorption at different temperatures. The sample FAS-10 exhibited a CO{sub 2

  15. Microstructural variation of hardened cement-fly ash pastes leached by soft water

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The microstructural variations of hardened cement-fly ash pastes leached by soft water were investigated by MIP, XRD, TG and SEM. The results show that the mass of hardened cement-fly ash paste reduces and its microstructure deteriorates partly after leaching of soft water. At the leaching duration of 180 days, the hardened paste containing fly ash deteriorated a little more serious than the plain cement paste, but the incorporation of fly ash in a proper ratio was helpful to defer the trend of deterioration of the hardened paste microstructure. The microstructural stability of hardened cement-fly ash paste wasn’t damaged severely during the 180 days leaching duration.

  16. Research on Existing Pattern of Carbon and Its Removal from Fly Ash

    Institute of Scientific and Technical Information of China (English)

    杨玉芬; 章新喜; 陈清如

    2002-01-01

    Flyash is a fine and dispersed powder discharged from power station a fter the coal being burned. With the deepening of people's recognition about the pollution problem of fly ash, the ways of utilizing fly ash are gradually incre asing. Utilizing value of fly ash is closely related to the unburned carbon cont ent.On the basis of analysis of modern testing method,a fundamental thinking I stheoretically posed for decreasing unburned carbon content from fly ash by a d ry removing carbon technology. The triboelectric separation method shown that the above-mentioned thinking of dry removing carbon from fly ash is practical.

  17. INFLUENCE OF FLY ASH REPLACEMENT ON STRENGTH PROPERTIES OF CEMENT MORTAR

    OpenAIRE

    AMARNATH YERRAMALA; BHASKAR DESAI V; RAMA CHANDURDU C

    2012-01-01

    Strength properties of fly ash mortars were evaluated through laboratory investigations. OPC of 53 grade replaced with class F fly ash with 5 - 25 % in the increments of 5 %. The results shown that at early age at all fly ash replacements the strength decreased with respect to normal mortar. However, after 28 days and above themortars made with fly ash replacement up to 15% resulted higher strength than normal OPC mortar. Fly ash replacement of 20 and 25% always had lower strength than normal...

  18. Investigation of Crack Width Development in Reinforced Concrete Beams Using Fly Ash

    Directory of Open Access Journals (Sweden)

    E. Bala Koteswara Rao

    2015-12-01

    Full Text Available Due to increase in thermal power plants in India lot of fly ash is produced. The disposal of fly ash causes negative impact on the environment in the way of water pollution, air pollution and finally effect on the eco system. Hence disposal of fly ash is challenging task for engineers. Lot of earlier investigations reported that fly ash has some cementing properties it can be replaced as cement upto some percentage. Hence in this investigation an attempt has been made to replace the cement by fly ash and investigated the resulting properties.

  19. Melting of municipal solid waste incinerator fly ash by waste-derived thermite reaction.

    Science.gov (United States)

    Wang, Kuen-Sheng; Lin, Kae-Long; Lee, Ching-Hwa

    2009-02-15

    This work describes a novel approach for melting municipal solid waste incinerator (MSWI) fly ash, based on self-propagating reactions, by using energy-efficient simulated waste-derived thermite. The self-propagating characteristics, the properties of the recycled alloy and slag and the partitioning of heavy metals during the process are also studied. Experimental results demonstrate that the mix ratio of fly ash to the starting mixture of less than 30% supports the development of the self-propagating reaction with a melting temperature of 1350-2200 degrees C. Furthermore, metallic iron (or alloy) and the slag were retrieved after activation of the thermite reactions among the starting mixtures. It was noted that more than 91wt.% of iron was retrieved as alloy and the rest of non-reductive oxides as slag. During the thermite reactions, the partition of heavy metals to the SFA and flue gas varied with the characteristics of the target metals: Cd was mainly partitioned to flue gas (75-82%), and partition slightly increased with the increasing fly ash ratio; Pb and Zn, were mainly partitioned to the SFA, and the partition increased with increasing fly ash ratio; Cu was partitioned to the SFA (18-31%) and was not found in the flue gas; and moreover stable Cr and Ni were not identified in both the SFA and flue gas. On the other hand, the determined TCLP leaching concentrations were all well within the current regulatory thresholds, despite the various FA ratios. This suggests that the vitrified fly ash samples were environmental safe in heavy metal leaching. The results of this study suggested that melting of municipal solid waste incinerator fly ash by waste-derived thermite reactions was a feasible approach not only energy-beneficial but also environmental-safe. PMID:18573610

  20. Microstructural and strength improvements through the use of Na{sub 2}CO{sub 3} in a cementless Ca(OH){sub 2}-activated Class F fly ash system

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Dongho; Jun, Yubin; Jeong, Yeonung; Oh, Jae Eun, E-mail: ohjaeeun@unist.ac.kr

    2015-01-15

    This study explores the beneficial effects of Na{sub 2}CO{sub 3} as an additive for microstructural and strength improvements in a Ca(OH){sub 2}-activated fly ash system. NaOH-activated fly ash samples were also tested to compare the effect of Na{sub 2}CO{sub 3}. Compressive strength testing, XRD, SEM/BSE/EDS, {sup 29}Si/{sup 27}Al MAS-NMR, MIP and TGA were performed. The testing results indicate that the use of Na{sub 2}CO{sub 3} for Ca(OH){sub 2}-activation led to a noticeable improvement in strength and microstructure, primarily due to (1) more dissolution of raw fly ash at an early age, (2) more formation of C–S–H [or C–S–H(I)], (3) porosity reduction, and (4) pore-size refinement. We also found that (1) an early high alkalinity from the NaOH formation was not a major cause of strength, (2) geopolymer was not formed despite the early NaOH formation, and (3) no visible pore-filling action of CaCO{sub 3} was observed. However, Na{sub 2}CO{sub 3} did not produce any improvement in strength for NaOH-activated fly ash. -- Highlights: •The use of Na{sub 2}CO{sub 3} significantly improved strength and microstructure. •The use of Na{sub 2}CO{sub 3} induced more dissolution of raw fly ash at early ages. •The use of Na{sub 2}CO{sub 3} promoted more C–S–H [or C–S–H(I)] formation. •The use of Na{sub 2}CO{sub 3} reduced total porosity and refined pore-size distribution. •The use of Na{sub 2}CO{sub 3} produced neither geopolymer formations nor pore-filling actions from CaCO{sub 3}.

  1. Waste Water Treatment-Bed of Coal Fly Ash for Dyes and Pigments Industry

    International Nuclear Information System (INIS)

    The highly porous power plant waste ashes have been utilized to treat toxic effluent of a dyes manufacturing plant. An attempt has been made for the first time in Pakistan, to generate an effective and economically sound treatment facility for the toxic effluent of a dyes manufacturing plant. This is an indigenous bed which could replace expensive treatment facilities, such as reverse osmosis (RO), granulated activated carbon (GAC) bed, etc. The treatment efficiency was improved by coupling coagulants with fly ash adsorbent bed. The ash was collected from coal fired boilers of power plant at Lakhra Power Generation Company, Jamshoro, Pakistan. The use of this ash resolved the disposal and environmental issues by treating wastewater of chemical, dyes and pigment industry. The treatment bed comprised of briquettes of coal fly ash coupled with commercial coagulant ferrous sulfate-lime reduced COD, color, turbidity and TSS of effluent remarkably. An adsorption capacity and chemical behavior of fly ash bed was also studied. In coagulation treatment, coagulant FeSO/sun 4/-lime influenced reduction of COD, color, turbidity and TSS by 32 percentage, 48 percentage, 50 percentage and 51 percentage, respectively. The CFAB coupled with coagulant, resulted an excessive removal of color, TSS, COD, and turbidity by 88 percentage, 92 percentage, 67 percentage and 89 percentage, respectively. (author)

  2. Waste Water Treatment-Bed of Coal Fly Ash for Dyes and Pigments Industry

    Directory of Open Access Journals (Sweden)

    Syed Farman Ali Shah

    2015-12-01

    Full Text Available The highly porous power plant waste ashes have been utilized to treat toxic effluent of a dyes manufacturing plant. An attempt has been made for the first time in Pakistan, to generate an effective and economically sound treatment facility for the toxic effluent of a dyes manufacturing plant. This is an indigenous bed which could replace expensive treatment facilities, such as reverse osmosis (RO, granulated activated carbon (GAC bed, etc. The treatment efficiency was improved by coupling coagulants with fly ash adsorbent bed. The ash was collected from coal fired boilers of power plant at Lakhra Power Generation Company, Jamshoro, Pakistan. The use of this ash resolved the disposal and environmental issues by treating wastewater of chemical, dyes and pigment industry. The treatment bed comprised of briquettes of coal fly ash coupled with commercial coagulant ferrous sulfate-lime reduced COD, color, turbidity and TSS of effluent remarkably. An adsorption capacity and chemical behavior of fly ash bed was also studied. In coagulation treatment, coagulant FeSO4-lime influenced reduction of COD, color, turbidity and TSS by 32%, 48%, 50% and 51%, respectively. The CFAB coupled with coagulant, resulted an excessive removal of color, TSS, COD, and turbidity by 88%, 92%, 67% and89%, respectively.

  3. Phenolic acids as bioindicators of fly ash deposit revegetation.

    Science.gov (United States)

    Djurdjević, L; Mitrović, M; Pavlović, P; Gajić, G; Kostić, O

    2006-05-01

    The floristic composition, the abundance, and the cover of pioneer plant species of spontaneously formed plant communities and the content of total phenolics and phenolic acids, as humus constituents, of an ash deposit after 7 years of recultivation were studied. The restoration of both the soil and the vegetation on the ash deposits of the "Nikola Tesla-A" thermoelectric power plant in Obrenovac (Serbia) is an extremely slow process. Unfavorable physical and chemical characteristics, the toxicity of fly ash, and extreme microclimatic conditions prevented the development of compact plant cover. The abundance and cover of plants increased from the central part of the deposit towards its edges (ranging from 1-80%). Festuca rubra L., Crepis setosa Hall., Erigeron canadensis L., Cirsium arvense (L.) Scop., Calamagrostis epigeios (L.) Roth., and Tamarix gallica L. were the most abundant species, thus giving the highest cover. Humus generated during the decomposition process of plant remains represents a completely new product absent in the ash as the starting material. The amount of total phenolics and phenolic acids (38.07-185.16 microg/g of total phenolics and 4.12-27.28 microg/g of phenolic acids) in fly ash increased from the center of the deposit towards its edges in correlation with the increase in plant abundance and cover. Ash samples contained high amounts of ferulic, vanillic, and p-coumaric acid, while the content of both p-hydroxybenzoic and syringic acid was relatively low. The presence of phenolic acids indicates the ongoing process of humus formation in the ash, in which the most abundant pioneer plants of spontaneously formed plant communities play the main role. Phenolic compounds can serve as reliable bioindicators in an assessment of the success of the recultivation process of thermoelectric power plants' ash deposits. PMID:16418890

  4. Phenolic acids as bioindicators of fly ash deposit revegetation.

    Science.gov (United States)

    Djurdjević, L; Mitrović, M; Pavlović, P; Gajić, G; Kostić, O

    2006-05-01

    The floristic composition, the abundance, and the cover of pioneer plant species of spontaneously formed plant communities and the content of total phenolics and phenolic acids, as humus constituents, of an ash deposit after 7 years of recultivation were studied. The restoration of both the soil and the vegetation on the ash deposits of the "Nikola Tesla-A" thermoelectric power plant in Obrenovac (Serbia) is an extremely slow process. Unfavorable physical and chemical characteristics, the toxicity of fly ash, and extreme microclimatic conditions prevented the development of compact plant cover. The abundance and cover of plants increased from the central part of the deposit towards its edges (ranging from 1-80%). Festuca rubra L., Crepis setosa Hall., Erigeron canadensis L., Cirsium arvense (L.) Scop., Calamagrostis epigeios (L.) Roth., and Tamarix gallica L. were the most abundant species, thus giving the highest cover. Humus generated during the decomposition process of plant remains represents a completely new product absent in the ash as the starting material. The amount of total phenolics and phenolic acids (38.07-185.16 microg/g of total phenolics and 4.12-27.28 microg/g of phenolic acids) in fly ash increased from the center of the deposit towards its edges in correlation with the increase in plant abundance and cover. Ash samples contained high amounts of ferulic, vanillic, and p-coumaric acid, while the content of both p-hydroxybenzoic and syringic acid was relatively low. The presence of phenolic acids indicates the ongoing process of humus formation in the ash, in which the most abundant pioneer plants of spontaneously formed plant communities play the main role. Phenolic compounds can serve as reliable bioindicators in an assessment of the success of the recultivation process of thermoelectric power plants' ash deposits.

  5. Elemental determinations in NBS 1633A Fly Ash Standard Reference material using INAA PGNAA

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, J.R.; Schlegel, S.C. (Missouri Univ., Columbia (USA). Research Reactor Facility)

    1985-02-01

    INAA was used for the determination of 23 elements, and prompt gamma neutron activation analysis (PGNAA) for the determination of 10 elements in U.S. National Bureau of Standards (NBS) 1633A Fly Ash Standard Reference Material. The results are in excellent agreement with the limited number of NBS certified values available.

  6. Simple Mechanical Beneficiation Method of Coarse Fly Ash with High LOI for Making HVFA Mortar

    Directory of Open Access Journals (Sweden)

    Antoni ,

    2015-01-01

    Full Text Available This study focusses on the effect of milling of fly ash obtained from four different sources on the properties of high volume fly ash (HVFA mortar. Two fly ash samples with low loss-on-ignition (LOI were taken from a coal-fired power plant, while the other two with high LOIs were obtained from a textile factory and from a paper mill, respectively. Milling was performed using a rod mill at a certain period of time. The workability of HVFA mortar with constant water to cementitious ratio was controlled by adjusting the superplasticizer content. The results show that the specific gravity of fly ash increases after milling. Utilizing milled fly ash ends up with significant strength increase of HVFA mortar, especially those utilizing high LOI fly ash. This shows that milling is an excellent fly ash beneficiation technique, especially on the one with high LOI value.

  7. Literature survey on phase composition of hardened cement paste containing fly ash

    International Nuclear Information System (INIS)

    The purpose of this literature survey is to collect the knowledge on the effect of fly ash in hardened cement paste and the information about evaluation of physicochemical performance based on phase composition of hardened cement paste. The performance of hardened cement paste containing fly ash is affected by the property of fly ash, hydration of cement and pozzolanic reaction of fly ash. Some properties of fly ash such as density and chemical composition are reflected in phase composition, showing the progress of cement hydration and pozzolanic reaction. Therefore clarification of the relationship of phase composition and performance will lead to appropriate evaluation of the property of fly ash. The amount of pore, chemical shrinkage, pore solution, compressive strength, Young modulus and alkali silica reaction have relations to the phase composition of hardened cement paste. It is considered as future subject to clarify the relationship of phase composition and performance for various properties of fly ash. (author)

  8. Utilization options for fly ash, bottom ash, and slag in Eastern Europe

    Energy Technology Data Exchange (ETDEWEB)

    Manz, O.E.

    1995-12-01

    Since 1967, at least six ash utilization symposiums have been held in the United States, with papers presented by several European authors on the utilization of coal by-products in Eastern Europe. There is currently over 80,000 megawatts of installed coal-fired capacity available in that region. Unfortunately, of the 117,778,000 tonnes of fly ash, bottom ash, and slag produced in Eastern Europe in 1989, only 13% was utilized. This paper outlines the research and levels and kinds of coal by-product utilization taking place in Eastern Europe since the late 1960s.

  9. Microstructure Development and Transport Properties of Portland Cement-fly Ash Binary Systems: in view of service life predictions

    NARCIS (Netherlands)

    Yu, Z.

    2015-01-01

    Fly ash is a by-product of burning coal in electric power generating plants. It is commonly known that owing to its pozzolanic properties fly ash is widely used as a partial replacement for Portland cement in concrete. The use of fly ash in concrete not only reduces the landfill costs of fly ash, bu

  10. Electrodialytic removal of heavy metals from different fly ashes. Influence of heavy metal speciation in the ashes

    DEFF Research Database (Denmark)

    Pedersen, Anne Juul; Ottosen, Lisbeth M.; Villumsen, Arne

    2003-01-01

    Electrodialytic Remediation has recently been suggested as a potential method for removal of heavy metals from fly ashes. In this work electrodialytic remediation of three different fly ashes, i.e. two municipal solid waste incinerator (MSWI) fly ashes and one wood combustion fly ash was studied...... in lab scale, and the results were discussed in relation to the expected heavy metal speciation in the ashes. In initial leaching experiments the pH-dependent desorption characteristics of the heavy metals Cd, Pb, Zn and Cu were analogous in the two MSWI ashes, and thus it was expected...... that the speciation of these metals was similar in the two ashes. On the other hand, the leaching behaviour (and concentration) of Cr was diverse. The apparent similar speciation of Cd, Pb, Zn and Cu was only partly confirmed in the following electrodialytic remediation experiments. Significant differences in re-moval...

  11. Fly ash: Analysis and characterization. (Latest citations from the EI Compendex*plus database). Published Search

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-08-01

    The bibliography contains citations concerning the analysis and characterization of fly ash. Topics cover x-ray classification, trace analysis, particle size distribution, ash morphology, surface adsorption, toxicity, and mutagenic fly ash. Fluidized-bed-combustion technology for coal-combustion systems to meet air-emission standards is examined. The use of fly ash in concrete and cement manufacturing is discussed. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  12. Fly ash: Analysis and characterization. (Latest citations from the EI Compendex*plus database). Published Search

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-05-01

    The bibliography contains citations concerning the analysis and characterization of fly ash. Topics cover x-ray classification, trace analysis, particle size distribution, ash morphology, surface adsorption, toxicity, and mutagenic fly ash. Fluidized-bed-combustion technology for coal-combustion systems to meet air-emission standards is examined. The use of fly ash in concrete and cement manufacturing is discussed. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  13. Products based on the mixes of fly ashes and fibre sludge (fibre-ashes) for road construction; Produkter baserade paa blandningar av flygaska och fiberslam (fiberaskor) foer vaegbyggande

    Energy Technology Data Exchange (ETDEWEB)

    Lahtinen, Pentti; Maijala Aino; Macsik, Josef

    2005-03-01

    The project has derived benefits from the earlier Finnish research and development as well as from the experience in the fibre-ash materials for geotechnical applications. The fly ashes used for the project have been taken from the same sources as the fly ashes for the earlier Vaermeforsk project 870: FACE. The project's objective was to develop construction materials based on mixtures of fibre sludge and fly ash for geotechnical applications, and for the final commercialisation of the fibre-ash materials. The mixtures are based on fly ashes from energy production (bark, peat and sludge used for incineration) and on kaolin containing fibre sludge from the paper industry. With help of laboratory tests the project has been searching for fibre ashes with excellent technical characteristics like good frost resistance combined with a good bearing capacity and resilience in geotechnical structures. The project's results has given additional knowledge about alternative road construction materials to construct technically good, sustainable and environmentally friendly roads and other constructions with lower costs than the conventional constructions. The results of laboratory tests have shown that this is possible. However, it has to be verified with help of field tests and pilot constructions. The first tasks of the project were to make choices of the appropriate fibre sludge and fly ashes for the project targets. The laboratory tests have been carried out in the geotechnical laboratory of Ramboll Finland Oy (earlier SCC Viatek Oy, SGT - later in the report SGT). After arrival of all test material in the laboratory the test programme started in order to find out the most optimal fibre-ash mixtures with or without any activator. The most potential mixtures were tested for their geotechnical long-term properties (mainly resistance against climatic load) and for their environmental risk potential. The results comprise of several technically, environmentally and

  14. USING FLY ASH TO STUDY ON THE MECHANISM OF THE ABSORPTION OF HEAVY METAL IONS IN WASTEWATER

    Institute of Scientific and Technical Information of China (English)

    程建光

    2000-01-01

    Using the method of sedentary thermal experiment, the use of fly ash to remove Zn2+,Cu2+ and Pb2+ in waste water was studied. Special attention was paid to the effects of pH and time degree of activity on absorbing ability. The freundlich model applicable to the absorption data was set. Also the mechanism of absorption and ultra-micro structure of fly ash with the help of TEM was put forward.

  15. Studies on Carbon-Fly Ash Composites with Chopped PANOX Fibers

    OpenAIRE

    Patel,Rakesh V; Manocha, S.

    2013-01-01

    Chemical analysis and morphological studies of fly ash reveals the complex chemical constituents present as spherical particles with diameter of less than 25 μm. The constituents of fly ash are silica, alumina, iron oxide, titanium dioxide, calcium and magnesium oxide, and other trace elements. The use of thermosetting as well thermoplastic polymer matrix has been made by several workers to develop polymer matrix fly ash particulate composites by using the hard and abrasive properties of fly ...

  16. The Effect of Lime Addition on the Setting Time and Strength of Ambient Cured Fly Ash Based Geopolymer Binder

    Directory of Open Access Journals (Sweden)

    Adam Andi Arham

    2016-01-01

    Full Text Available One of the limitations of geopolymer as the alternative binders in concrete is the necessity of heat curing. This study aimed to produce fly ash geopolymer binder subjected to ambient curing by adding a small proportion of lime and varying the activator dosage. The Class F fly ash from Mpanau coal-fired power plant was mixed with alkaline solution consists of sodium silicate and sodium hydroxide with Na2O dosage of 5%, 7%, and 9%. To achieve ambient cured paste, 8%, 9%, and 10% slaked lime was added as the substitute for the fly ash. The setting time test was conducted for each mix and the compressive strength was performed at age of 7, 14 and 28 days. The test result shows that the setting time of the fly ash based geopolymer paste can be controlled by adding a small proportion of slaked lime. The addition of lime increased strength but decreased the setting time.

  17. Preparation of heteropolyacid/TiO2/fly-ash-cenosphere photocatalyst for the degradation of ciprofloxacin from aqueous solutions

    Science.gov (United States)

    Wu, Di; Huo, Pengwei; Lu, Ziyang; Gao, Xun; Liu, Xiaolin; Shi, Weidong; Yan, Yongsheng

    2012-07-01

    The TiO2/fly-ash cenosphere photocatalysts modified with heteropolyacid were synthesized by sol-gel followed solvothermal method at 40 °C. Their chemical composition and optical absorption were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectra (UV-vis DRS), Fourier Transform Infra Red spectroscopy (FTIR) and Scanning electron microscopy (SEM). It was found that heteropolyacid modification could facilitate the absorption edge of TiO2/fly-ash cenosphere photocatalyst to shift the visible light region. Heteropolyoxanion could be loaded on the titanium dioxide surface, by which could hinder the recombination rate of excited electron holes. The photocatalytic activity of TiO2/fly-ash cenospheres modified with heteropolyacid was observed for the degradation of ciprofloxacin (CPFX) under visible light irradiation. The result from degradation of CPFX suggested that the photocatalytic activity of TiO2/fly-ash cenospheres modified with silicotungstic acid was superior. The synergistic effects of heteropolyacid in modified TiO2/fly-ash cenospheres photocatalyst particles were responsible for improving visible light photocatalytic activity. Besides, the novel photocatalyst was easy to recycle during post treatment because the fly-ash cenosphere was adopted for carrier.

  18. Preparation of heteropolyacid/TiO2/fly-ash-cenosphere photocatalyst for the degradation of ciprofloxacin from aqueous solutions

    International Nuclear Information System (INIS)

    The TiO2/fly-ash cenosphere photocatalysts modified with heteropolyacid were synthesized by sol-gel followed solvothermal method at 40 °C. Their chemical composition and optical absorption were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectra (UV-vis DRS), Fourier Transform Infra Red spectroscopy (FTIR) and Scanning electron microscopy (SEM). It was found that heteropolyacid modification could facilitate the absorption edge of TiO2/fly-ash cenosphere photocatalyst to shift the visible light region. Heteropolyoxanion could be loaded on the titanium dioxide surface, by which could hinder the recombination rate of excited electron holes. The photocatalytic activity of TiO2/fly-ash cenospheres modified with heteropolyacid was observed for the degradation of ciprofloxacin (CPFX) under visible light irradiation. The result from degradation of CPFX suggested that the photocatalytic activity of TiO2/fly-ash cenospheres modified with silicotungstic acid was superior. The synergistic effects of heteropolyacid in modified TiO2/fly-ash cenospheres photocatalyst particles were responsible for improving visible light photocatalytic activity. Besides, the novel photocatalyst was easy to recycle during post treatment because the fly-ash cenosphere was adopted for carrier.

  19. Thermal treatment and utilization of Al-rich waste in high calcium fly ash geopolymeric materials

    Science.gov (United States)

    Chindaprasirt, Prinya; Rattanasak, Ubolluk; Vongvoradit, Pimdao; Jenjirapanya, Supichart

    2012-09-01

    The Al-rich waste with aluminium and hydrocarbon as the major contaminant is generated at the wastewater treatment unit of a polymer processing plant. In this research, the heat treatment of this Al-rich waste and its use to adjust the silica/alumina ratio of the high calcium fly ash geopolymer were studied. To recycle the raw Al-rich waste, the waste was dried at 110°C and calcined at 400 to 1000°C. Mineralogical analyses were conducted using X-ray diffraction (XRD) to study the phase change. The increase in calcination temperature to 600, 800, and 1000°C resulted in the phase transformation. The more active alumina phase of active γ-Al2O3 was obtained with the increase in calcination temperature. The calcined Al-rich waste was then used as an additive to the fly ash geopolymer by mixing with high calcium fly ash, water glass, 10 M sodium hydroxide (NaOH), and sand. Test results indicated that the calcined Al-rich waste could be used as an aluminium source to adjust the silica/alumina ratio and the strength of geopolymeric materials. The fly ash geopolymer mortar with 2.5wt% of the Al-rich waste calcined at 1000°C possessed the 7-d compressive strength of 34.2 MPa.

  20. Sequestration of carbon dioxide by indirect mineralization using Victorian brown coal fly ash.

    Science.gov (United States)

    Sun, Yong; Parikh, Vinay; Zhang, Lian

    2012-03-30

    The use of an industry waste, brown coal fly ash collected from the Latrobe Valley, Victoria, Australia, has been tested for the post-combustion CO(2) capture through indirect minersalization in acetic acid leachate. Upon the initial leaching, the majority of calcium and magnesium in fly ash were dissolved into solution, the carbonation potential of which was investigated subsequently through the use of a continuously stirred high-pressure autoclave reactor and the characterization of carbonation precipitates by various facilities. A large CO(2) capture capacity of fly ash under mild conditions has been confirmed. The CO(2) was fixed in both carbonate precipitates and water-soluble bicarbonate, and the conversion between these two species was achievable at approximately 60°C and a CO(2) partial pressure above 3 bar. The kinetic analysis confirmed a fast reaction rate for the carbonation of the brown coal ash-derived leachate at a global activation energy of 12.7 kJ/mol. It is much lower than that for natural minerals and is also very close to the potassium carbonate/piperazine system. The CO(2) capture capacity of this system has also proven to reach maximum 264 kg CO(2)/ton fly ash which is comparable to the natural minerals tested in the literature. As the fly ash is a valueless waste and requires no comminution prior to use, the technology developed here is highly efficient and energy-saving, the resulting carbonate products of which are invaluable for the use as additive to cement and in the paper and pulp industry. PMID:22326240

  1. Mechanical properties and microstructure analysis of fly ash geopolymeric recycled concrete

    Energy Technology Data Exchange (ETDEWEB)

    Shi, X.S. [College of Architecture and Environment, Sichuan University, Chengdu (China); Collins, F.G.; Zhao, X.L. [Department of Civil Engineering, Monash University, Clayton (Australia); Wang, Q.Y., E-mail: wangqy@scu.edu.cn [College of Architecture and Environment, Sichuan University, Chengdu (China)

    2012-10-30

    Highlights: Black-Right-Pointing-Pointer Sodium silicate solution and sodium hydroxide solution were used to activate fly ash, which substitute cement totally in the concrete. Black-Right-Pointing-Pointer Utilizing two kinds of waste materials (fly ash and recycled aggregates) at the same time. Black-Right-Pointing-Pointer The mechanical properties and microstructures were studied and compared with different recycled aggregates replacement ratios. Black-Right-Pointing-Pointer Such concrete has greater compressive strength and better microstructure than ordinary concrete and also geopolymer concrete. - Abstract: Six mixtures with different recycled aggregate (RA) replacement ratios of 0%, 50% and 100% were designed to manufacture recycled aggregate concrete (RAC) and alkali-activated fly ash geopolymeric recycled concrete (GRC). The physical and mechanical properties were investigated indicating different performances from each other. Optical microscopy under transmitted light and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX) were carried out in this study in order to identify the mechanism underlying the effects of the geopolymer and RA on concrete properties. The features of aggregates, paste and interfacial transition zone (ITZ) were compared and discussed. Experimental results indicate that using alkali-activated fly ash geopolymer as replacement of ordinary Portland cement (OPC) effectively improved the compressive strength. With increasing of RA contents in both RAC and GRC, the compressive strength decreased gradually. The microstructure analysis shows that, on one hand, the presence of RA weakens the strength of the aggregates and the structure of ITZs; on the other hand, due to the alkali-activated fly ash in geopolymer concrete, the contents of Portlandite (Ca(OH){sub 2}) and voids were reduced, as well as improved the matrix homogeneity. The microstructure of GRC was changed by different reaction products, such

  2. Surface modification of oil fly ash and its application in selective capturing of carbon dioxide

    Science.gov (United States)

    Yaumi, Ali L.; Hussien, Ibnelwaleed A.; Shawabkeh, Reyad A.

    2013-02-01

    Oil fly ash from power generation plants was activated with 30% NH4OH and used for selective adsorption of carbon dioxide from CO2/N2 mixture. The treated samples were characterized for their surface area, morphology, crystalline phase, chemical composition and surface functional groups. Energy dispersive X-ray analysis showed an increase in the carbon contents from 45 to 73 wt% as a result of leaching out metal oxides. XRD proved that chemical activation of ash resulted in diminishing of major crystalline phases of zeolite, and other alumino-silicates leaving only quartz and mullite. BET analysis showed an increase in surface area from 59 to 318 m2/g after chemical activation and the pore volume increased from 0.0368 to 0.679 cm3/g. This increase in pore volume is supported by the results of SEM, where more micropores were opened with well-defined particle sizes and porous structure. The TGA of the treated fly ash showed stability at higher temperature as the weight loss decreased with increasing temperature. For treated ash, the FTIR displayed new peaks of amine functional group. The treated ash was used for the removal of CO2 from CO2/N2 mixture and the maximum adsorption/capturing capacity was found to be 240 mg/g. This capacity increases with increase in initial gas concentration, inlet flow rate and temperature suggesting the endothermic nature of the interaction between the gas molecules and the surface of the ash.

  3. Compressive strength and microstructural analysis of fly ash/palm oil fuel ash based geopolymer mortar

    International Nuclear Information System (INIS)

    Highlights: • Results show POFA is adaptable as replacement in FA based geopolymer mortar. • The increase in POFA/FA ratio delay of the compressive development of geopolymer. • The density of POFA based geoploymer is lower than FA based geopolymer mortar. - Abstract: This paper presents the effects and adaptability of palm oil fuel ash (POFA) as a replacement material in fly ash (FA) based geopolymer mortar from the aspect of microstructural and compressive strength. The geopolymers developed were synthesized with a combination of sodium hydroxide and sodium silicate as activator and POFA and FA as high silica–alumina resources. The development of compressive strength of POFA/FA based geopolymers was investigated using X-ray florescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and field emission scanning electron microscopy (FESEM). It was observed that the particle shapes and surface area of POFA and FA as well as chemical composition affects the density and compressive strength of the mortars. The increment in the percentages of POFA increased the silica/alumina (SiO2/Al2O3) ratio and that resulted in reduction of the early compressive strength of the geopolymer and delayed the geopolymerization process

  4. Transformation of flying ash in new materials according tetrad getting - structure - properties - application

    International Nuclear Information System (INIS)

    The obtainment of a dense and porous ceramic from fly ash, composites ceramic from clay and fly ash, glass-ceramic from fly ash and glass-ceramic composites from fly ash and waste glass was the aim of this doctoral thesis. Several types of fly ashes from the power plant REK Bitola was used. The waste materials were specified from chemical, structural, thermo chemical, thermo physical and geometrical aspect. Consolidation of the fly ashes was performed in the temperature interval from 950°C to 1100°C/1h with a heating rate of 3 and 10°/min. The process of optimization was conducted based on the influence of the main process parameters and their interactions on the properties of the ceramic. The properties of the compacts were specified by density, mechanical properties and technical coefficient of the thermal expansion. The density of the compacts vary from 1.60 to 2.37 g/cm3, bending strength from 5 MPa up to 47MPa, E-modulus from 3 to 23GPa, compression strength from 20 to 170 MPa. Porosity of the compacts was in the range from 36 to 5%. The technical coefficient of the thermal expansion was between 8.31 and 9.10 *10-6/°C. Mechanical activation was applied in order to increase the geometrical and structural factor of activity. After mechanical activation of 5 and 10h the specific surface area increased to 53.7% and 94% compare with the as-received. Obtained mechanical properties of the compacts were from 5 to 80 MPa for bending strength, E- modulus from 2 to 37 GPa and porosity from 43 to 5%. Ceramic composites were obtained by mixing fly ash and clay. The clay was specified from chemical, structural, thermo physical and physical aspects. The determination of physical and chemical properties, mechanical and thermo physical properties of the clay-fly ash composites were done. Optimal properties posses the composite produced from 60% clay and 40% fly ash. Bending strength, e-modulus, compression strength were 50 MPa, 25 GPa 100 MPa, respectively. Porosity of the

  5. Kaliophilite from fly ash: synthesis, characterization and stability

    Indian Academy of Sciences (India)

    Yao Zhitong; Xia Meisheng; Ye Ying; Zhang Lu

    2011-12-01

    Kaliophilite was synthesized by fusion method using fly ash as starting material. In this method, at first, alkaline fusion of fly ash with KOH occurs, followed by hydrothermal treatment in KOH medium. Scanning electron microscopy (SEM) observations revealed that the synthesized kaliophilite (S-KAL) was a plate-like crystal. X-ray diffraction (XRD) results showed three characteristic diffraction peaks located at 2 = 19.56°, 20.78° and 28.71°, respectively. The thermal analysis indicated that the S-KAL had remarkable thermal stability when heated to 1000°C. Leaching test confirmed the high retention rate of potassium for S-KAL in boiling water for 10 h.

  6. Electrodialytic upgrading of municipal waste incineration fly ash for reuse

    DEFF Research Database (Denmark)

    Jensen, Pernille Erland; Kirkelund, Gunvor Marie; Ottosen, Lisbeth M.

    2012-01-01

    As incineration becomes a more widespread means of waste treatment, volumes of incineration residues increase and new means of handling become a demand. Municipal Solid Waste Incineration (MSWI) fly ash is hazardous material, which is presently disposed off as such; primarily due to its high...... content of water soluble, mobile salts and heavy metals. It was shown that the mobility of salts and toxic elements can be significantly reduced by extraction with electrodialysis in stack [1, 2]; and that treated MSWI fly ash may potentially be utilized as a substitute for cement in concrete [3...... to investigate the leachability of salts and toxic elements as a function of treatment time and current density. Results show that a delicate balance between pH and treatment-time exist and that continuous monitoring of pH and conductivity may be used for controlling of the process at an industrial scale...

  7. Sulfur removal from lignite by oxydesulfurization using fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Yaman, S.; Kucukbayrak, S. [Istanbul Technical University, Istanbul (Turkey). Chemical Engineering Dept.

    1997-01-01

    Since fly ash contains alkaline oxides, it is possible to use its water-extractable components as a desulfurization agent. This was investigated using some high-sulfur Turkish lignites. The effects of the amount of fly ash used, temperature, partial pressure of oxygen and time were studied in the range 5-40 g, 403-498 K, 0.0-1.5 MPa and 15-90 min respectively. The extents of pyritic and organic sulfur removal and recoveries of coal and calorific value were investigated for each of these variables. Reactivity and some combustion characteristics (ignition temperature, end temperature of combustion and combustion rate) of original and desulfurzed lignite samples were compared using combustion curves obtained from thermogravimetric analysis (t.g.a) results. FT-i.r. spectroscopy was used to determine the effects of the desulfurization process on the coal structure. 5 refs., 6 figs.,4 tabs.

  8. Properties of high fly ash content cellular concrete

    Energy Technology Data Exchange (ETDEWEB)

    Neufeld, R.D.; Vallejo, L.E.; Hu, W.; Latona, M.; Carson, C.; Kelly, C. (Univ. of Pittsburgh, PA (United States). Dept. of Civil and Environmental Engineering)

    1994-04-01

    High fly ash content autoclaved cellular concrete is produced by adding calibrated quantities of aluminum powder to a mixture of fly ash (60% wt/wt), cement, and water. The foamed product is hardened in an autoclave with pressurized steam at about 180 C. Block material for samples tested originated from a mobile pilot plant that toured sites of United States-based electric utilities. Compressive strengths of the foamed product were controlled to the range of 300--600 psi, with dry weight densities on the order of 32--37 lb/cu ft. Heavy metal concentrations in TCLP, ASTM, and synthetic acid rain leachates were on the order one to 10 times that found in Pittsburgh tap water, and never approached 100 times drinking water standards. Organic contents of leachates were not detectable. Controlling pore distributions appears to influence density, moisture accumulation rates, and mechanical/physical properties that are significant for construction.

  9. Leachate and radon production from fly ash autoclaved cellular concrete

    Energy Technology Data Exchange (ETDEWEB)

    Latona, M.C.; Neufeld, R.D.; Vallejo, L.E.; Brandon, D.; Hu, W.; Kelly, C. [Univ. of Pittsburgh, PA (United States). Dept. of Civil and Environmental Engineering

    1997-08-01

    Environmental consequences and potential liabilities of autoclaved cellular concrete (ACC) use were assessed by aqueous leaching of crushed samples for metals and organic solvent extractions of solid ACC for polycyclic aromatic hydrocarbons (PAHs). Also, whole ACC blocks were tested for radon exhalation potential. Results show leachate concentrations were typically 10 times below, and always 100 times below the regulatory threshold of applicable drinking water standards. A Microtox bioassay procedure showed no toxic effects due to leached metals. Organic analysis of solvent extracts indicated no release of hazardous PAHs attributable to the fly ash ingredient of ACC. Measured rates of radon exhalation were too low to cause potentially dangerous buildups in confined air spaces. Fly ash ACC may be characterized as an environmentally green construction material based on these findings.

  10. Utilization of blended fluidized bed combustion (FBC) ash and pulverized coal combustion (PCC) fly ash in geopolymer.

    Science.gov (United States)

    Chindaprasirt, Prinya; Rattanasak, Ubolluk

    2010-04-01

    In this paper, synthesis of geopolymer from fluidized bed combustion (FBC) ash and pulverized coal combustion (PCC) fly ash was studied in order to effectively utilize both ashes. FBC-fly ash and bottom ash were inter-ground to three different finenesses. The ashes were mixed with as-received PCC-fly ash in various proportions and used as source material for synthesis of geopolymer. Sodium silicate (Na(2)SiO(3)) and 10M sodium hydroxide (NaOH) solutions at mass ratio of Na(2)SiO(3)/NaOH of 1.5 and curing temperature of 65 degrees C for 48h were used for making geopolymer. X-ray diffraction (XRD), scanning electron microscopy (SEM), degree of reaction, and thermal gravimetric analysis (TGA) were performed on the geopolymer pastes. Compressive strength was also tested on geopolymer mortars. The results show that high strength geopolymer mortars of 35.0-44.0MPa can be produced using mixture of ground FBC ash and as-received PCC-fly ash. Fine FBC ash is more reactive and results in higher degree of reaction and higher strength geopolymer as compared to the use of coarser FBC ash. Grinding increases reactivity of ash by means of increasing surface area and the amount of reactive phase of the ash. In addition, the packing effect due to fine particles also contributed to increase in strength of geopolymers.

  11. Hydration studies of calcium sulfoaluminate cements blended with fly ash

    OpenAIRE

    Garcia-Maté, Marta; De la Torre, Angeles G; León-Reina, Laura; Aranda, Miguel A. G.; Santacruz, Isabel

    2013-01-01

    The main objective of this work is to study the hydration and properties of calciumsulfoaluminate cement pastes blended with fly ash (FA) and the corresponding mortars at different hydration ages. Laboratory X-ray powder diffraction, rheological studies, thermal analysis, porosimetry and compressive strength measurements were performed. The analysis of the diffraction data by Rietveld method allowed quantifying crystalline phases and overall amorphous contents. The studied paramet...

  12. The production technology of shale fly ash fired brick

    Institute of Scientific and Technical Information of China (English)

    JiaoYuhua

    2005-01-01

    When we construct the shale fly-ash fired brick production line, the first of all is that we must explored mineral raw material in detailed, and prove up the exploitable storage,so that the storage of raw material can supply the production line adequately when the factory has been set up.The second is that we must analyze the raw material completely. According to the raw material basic properties,we can decide process of the brick making.

  13. An investigation of radon exhalation rate and estimation of radiation doses in coal and fly ash samples.

    Science.gov (United States)

    Mahur, A K; Kumar, Rajesh; Mishra, Meena; Sengupta, D; Prasad, Rajendra

    2008-03-01

    Coal is a technologically important material used for power generation. Its cinder (fly ash) is used in the manufacturing of bricks, sheets, cement, land filling etc. Coal and its by-products often contain significant amounts of radionuclides, including uranium which is the ultimate source of the radioactive gas radon. Burning of coal and the subsequent atmospheric emission cause the redistribution of toxic radioactive trace elements in the environment. In the present study, radon exhalation rates in coal and fly ash samples from the thermal power plants at Kolaghat (W.B.) and Kasimpur (U.P.) have been measured using sealed Can technique having LR-115 type II detectors. The activity concentrations of 238U, 232Th, and 40K in the samples of Kolaghat power station are also measured. It is observed that the radon exhalation rate from fly ash samples from Kolaghat is higher than from coal samples and activity concentration of radionuclides in fly ash is enhanced after the combustion of coal. Fly ash samples from Kasimpur show no appreciable change in radon exhalation. Radiation doses from the fly ash samples have been estimated from radon exhalation rate and radionuclide concentrations.

  14. DETERMINING THE ROLE OF INDIVIDUAL FLY ASH PARTICLES IN INFLUENCING THE VARIATION IN THE OVERALL PHYSICAL, MORPHOLOGICAL, AND CHEMICAL PROPERTIES OF FLY ASH

    Directory of Open Access Journals (Sweden)

    Usman Haider

    2016-08-01

    Full Text Available The properties of fly ashes vary because of the differences in the properties of their individual particles, and the determination of variation in these properties is of interest to the industries which use pulverized raw fly ash in applications, such as in cementitious materials and in the recovery of certain rare elements from raw fly ash. To investigate the differences in individual particles, four pulverized raw fly ashes from thermal power plants of the Czech Republic were used in this research. It was observed from FE-SEM that all four fly ashes consist of glassy hollow spherical, solid spherical, porous spherical, bright spherical, porous slaggy and compact slaggy particles. Box and whisker diagrams were plotted from the data of EDX individual particle analyses, which showed that the data of percentages for the Si, Al, and Fe elements is more scattered as compared to other elements. It was further observed from ternary phase diagrams and pseudo coloured images, that nature of fly ash particles changes from alumino silicate glassy to alumino silicate calcite metallic to pure ferro-metallic,where glassy particles showed high percentages and pure calcite particles were absent in fly ashes. Furthermore, a comparison between the XRF, the EDX total area analyses, showed that the EDX individual particle analysis gives more realistic and reliable data with median, mean, and the standard deviation for percentages of each element present in the fly ashes.

  15. Fly ash, basic slag and Glenbrook slag toxicity in cattle

    Energy Technology Data Exchange (ETDEWEB)

    Dewes, H.F.; McLeay, L.M.; Harfoot, C.G.

    1995-06-01

    In case studies of two herds of dairy cattle, a herd of 270 Friesian cows and heifers and a herd of 256 Jersey cows and heifers experienced high death rates and a protracted course of illness when fly ash was broadcast as a fertiliser over the farms at a rate of about 1 tonne per hectare. The onset of weakness, lassitude and diarrhoea in the cattle first appeared within 4-5 days and both fertility and milk fat production fell off dramatically. In the following 7 months, 51 animals died in the Friesian herd and a similar death rate and performance losses occurred in the Jersey herd. Emaciation and hepatic fibrosis were consistently reported from autopsies. Heavy metal poisoning was eliminated from the possible diagnosis. The slags and fly ash used as fertiliser had several features in common. They contained 29-40% calcium as calcium oxide, 15-35 grams of iron per kg, they were all extremely alkaline and concentrations of lead and arsenic were low. The effect of adding fly ash to rumen contents in vitro was to raise the pH to greater than 7.2, at which point fermentation was markedly reduced.

  16. Treatment of MSW fly ashes using the electrodialytic remediation technique

    DEFF Research Database (Denmark)

    Ferreira, Celia; Ribeiro, Alexandra B.; Ottosen, Lisbeth M.

    2004-01-01

    In the present work the electrodialytic remediation technique is applied for the treatment of fly ash, a hazardous by-product resulting from the incineration of municipal solid waste. Results are presented for an experiment conducted for 40 days at 38 mA, with a continuously stirred cell. Experim......In the present work the electrodialytic remediation technique is applied for the treatment of fly ash, a hazardous by-product resulting from the incineration of municipal solid waste. Results are presented for an experiment conducted for 40 days at 38 mA, with a continuously stirred cell....... Experimental parameters monitored include voltage drop, pH and electrolyte's volumes. Evolution of heavy metal concentration with time in the different compartments is analysed. The performance of sodium gluconate for heavy metals extraction from fly ash in different pH conditions is evaluated in batch...... extraction tests and during the electrodialytic treatment. This substance was found to perform well for pH below 6 and above 9, although extractions are better in the acidic region. Other relevant observations include the retention of significant amounts of heavy metals on the cation-exchange membrane...

  17. Chlorides behavior in raw fly ash washing experiments

    International Nuclear Information System (INIS)

    Chloride in fly ash from municipal solid waste incinerators (MSWIs) is one of the obstructive substances in recycling fly ash as building materials. As a result, we have to understand the behavior of chlorides in recycling process, such as washing. In this study, we used X-ray absorption near edge structure (XANES) and X-ray diffraction (XRD) to study the chloride behavior in washed residue of raw fly ash (RFA). We found that a combination of XRD and XANES, which is to use XRD to identify the situation of some compounds first and then process XANES data, was an effective way to explain the chlorides behavior in washing process. Approximately 15% of the chlorine in RFA was in the form of NaCl, 10% was in the form of KCl, 51% was CaCl2, and the remainder was in the form of Friedel's salt. In washing experiments not only the mole percentage but also the amount of soluble chlorides including NaCl, KCl and CaCl2 decreases quickly with the increase of liquid to solid (L/S) ratio or washing frequency. However, those of insoluble chlorides decrease slower. Moreover, Friedel's salt and its related compound (11CaO.7Al2O3.CaCl2) were reliable standards for the insoluble chlorides in RFA, which are strongly related to CaCl2. Washing of RFA promoted the release of insoluble chlorides, most of which were in the form of CaCl2.

  18. Greenlandic Waste Incineration Fly And Bottom Ash As Secondary Resource In Mortar

    DEFF Research Database (Denmark)

    Kirkelund, Gunvor Marie; Ottosen, Lisbeth M.; Jensen, Pernille Erland;

    2016-01-01

    , the effects on compressive strengths of mortars by substituting cement or sand by raw, washed and electrodialytically treated fly ash or bottom ash were investigated. Parts of the experimental fly ash had been pre-treated by either washing with distilled water or electro-dialytically treated to remove salts...

  19. Electrodialytic remediation of fly ash from co-combustion of wood and straw

    DEFF Research Database (Denmark)

    Chen, Wan; Jensen, Pernille Erland; Ottosen, Lisbeth M.;

    2015-01-01

    The heavy metal content in fly ash from biomass combustion, such as straw, wood and sludge, often needs reducing before the ash can be used as fertilizer for agricultural land or as a component in the production of construction materials. In this study, fly ash from a boiler fueled with wood chip...

  20. Improving lithium-ion battery performances by adding fly ash from coal combustion on cathode film

    Energy Technology Data Exchange (ETDEWEB)

    Dyartanti, Endah Retno; Jumari, Arif, E-mail: arifjumari@yahoo.com; Nur, Adrian; Purwanto, Agus [Research Group of Battery & Advanced Material, Department of Chemical Engineering, Sebelas Maret University, Jl. Ir. Sutami 36 A Kentingan, Surakarta Indonesia 57126 (Indonesia)

    2016-02-08

    A lithium battery is composed of anode, cathode and a separator. The performance of lithium battery is also influenced by the conductive material of cathode film. In this research, the use of fly ash from coal combustion as conductive enhancer for increasing the performances of lithium battery was investigated. Lithium iron phosphate (LiFePO{sub 4}) was used as the active material of cathode. The dry fly ash passed through 200 mesh screen, LiFePO{sub 4} and acethylene black (AB), polyvinylidene fluoride (PVDF) as a binder and N-methyl-2-pyrrolidone (NMP) as a solvent were mixed to form slurry. The slurry was then coated, dried and hot pressed to obtain the cathode film. The ratio of fly ash and AB were varied at the values of 1%, 2%, 3%, 4% and 5% while the other components were at constant. The anode film was casted with certain thickness and composition. The performance of battery lithium was examined by Eight Channel Battery Analyzer, the composition of the cathode film was examined by XRD (X-Ray Diffraction), and the structure and morphology of the anode film was analyzed by SEM (Scanning Electron Microscope). The composition, structure and morphology of cathode film was only different when fly ash added was 4% of AB or more. The addition of 2% of AB on cathode film gave the best performance of 81.712 mAh/g on charging and 79.412 mAh/g on discharging.

  1. Mechanical Properties of Aluminum Matrix Composite Reinforced by Carbothermally Reduced of Fly Ash

    Science.gov (United States)

    Jamasri, Wildan, M. W.; Sulardjaka, Kusnanto

    2011-01-01

    The addition of fly ash into aluminum as reinforcement can potentially reduce the production cost and density of aluminum. However, mechanical properties of aluminum matrix composite reinforced by fly ash (MMC ALFA) have some limitations due to the characteristic of fly ash. In this study, a carbothermal reduction process of fly ash and activated carbon powder with particle size <32 μm was performed prior to produce MMC ALFA. The process was carried out in a furnace at 1300° C in vacuum condition under argon flow. Synthesis product was analyzed by XRD with Cu-Kα radiation. From XRD analysis, it shows that the synthesis process can produce SiC powder. The synthesis product was subsequently used as reinforcement particle. Aluminum powder was mixed with 5, 10 and 15% of the synthesized powder, and then uni-axially compacted at pressure of 300 MPa. The compacted product was sintered for 2 hours in argon atmosphere at temperature variation of 550 and 600° C. Flexural strength, hardness and density of MMC ALFA's product were respectively evaluated using a four point bending test method based on ASTM C1161 standard, Brinell hardness scale and Archimedes method. The result of this study shows that the increase of weight of reinforcement can significantly increase the hardness and flexural strength of MMCs. The highest hardness and flexural strength of the MMC product are 300 kg/mm2 and 107.5 MPa, respectively.

  2. Effects of Characteristics of Fly Ash on the Properties of Geopolymer

    Institute of Scientific and Technical Information of China (English)

    杜海燕; 杨立娜; 高婉琪; 刘家臣

    2016-01-01

    The properties of two types of fly ash geopolymers made from class F fly ashes produced in wet bottom and dry bottom boilers were investigated in the present study. The source material used in the geopolymer concrete was activated with sodium hydroxide and sodium silicate solution. The results revealed that the geopolymer pro-duced with wet bottom boiler fly ash(CZ-FA)hardened quickly, and had higher early-age strength and lower shrinkage than the geopolymer produced with dry bottom boiler fly ash(SX-FA). The compressive strength of the two geopolymers made from CZ-FA and SX-FA was 45 MPa and 15 MPa respectively when cured at 60℃ and delayed for 14 d. However, after 90 days’ delay, the compressive strength of both the samples is almost the same, up to 80 MPa. Nearly 20% volume shrinkage of the samples made from SX-FA was much higher than that made from CZ-FA, which was almost zero. XRD, SEM/EDS and FT-IR were used to analyze the main reason of the dif-ferences.

  3. Improving lithium-ion battery performances by adding fly ash from coal combustion on cathode film

    International Nuclear Information System (INIS)

    A lithium battery is composed of anode, cathode and a separator. The performance of lithium battery is also influenced by the conductive material of cathode film. In this research, the use of fly ash from coal combustion as conductive enhancer for increasing the performances of lithium battery was investigated. Lithium iron phosphate (LiFePO4) was used as the active material of cathode. The dry fly ash passed through 200 mesh screen, LiFePO4 and acethylene black (AB), polyvinylidene fluoride (PVDF) as a binder and N-methyl-2-pyrrolidone (NMP) as a solvent were mixed to form slurry. The slurry was then coated, dried and hot pressed to obtain the cathode film. The ratio of fly ash and AB were varied at the values of 1%, 2%, 3%, 4% and 5% while the other components were at constant. The anode film was casted with certain thickness and composition. The performance of battery lithium was examined by Eight Channel Battery Analyzer, the composition of the cathode film was examined by XRD (X-Ray Diffraction), and the structure and morphology of the anode film was analyzed by SEM (Scanning Electron Microscope). The composition, structure and morphology of cathode film was only different when fly ash added was 4% of AB or more. The addition of 2% of AB on cathode film gave the best performance of 81.712 mAh/g on charging and 79.412 mAh/g on discharging

  4. Improving lithium-ion battery performances by adding fly ash from coal combustion on cathode film

    Science.gov (United States)

    Dyartanti, Endah Retno; Jumari, Arif; Nur, Adrian; Purwanto, Agus

    2016-02-01

    A lithium battery is composed of anode, cathode and a separator. The performance of lithium battery is also influenced by the conductive material of cathode film. In this research, the use of fly ash from coal combustion as conductive enhancer for increasing the performances of lithium battery was investigated. Lithium iron phosphate (LiFePO4) was used as the active material of cathode. The dry fly ash passed through 200 mesh screen, LiFePO4 and acethylene black (AB), polyvinylidene fluoride (PVDF) as a binder and N-methyl-2-pyrrolidone (NMP) as a solvent were mixed to form slurry. The slurry was then coated, dried and hot pressed to obtain the cathode film. The ratio of fly ash and AB were varied at the values of 1%, 2%, 3%, 4% and 5% while the other components were at constant. The anode film was casted with certain thickness and composition. The performance of battery lithium was examined by Eight Channel Battery Analyzer, the composition of the cathode film was examined by XRD (X-Ray Diffraction), and the structure and morphology of the anode film was analyzed by SEM (Scanning Electron Microscope). The composition, structure and morphology of cathode film was only different when fly ash added was 4% of AB or more. The addition of 2% of AB on cathode film gave the best performance of 81.712 mAh/g on charging and 79.412 mAh/g on discharging.

  5. Microstructure and mechanical properties of aluminum–fly ash nano composites made by ultrasonic method

    International Nuclear Information System (INIS)

    Highlights: ► Nano structured fly ash has been produced by 30 h milling time. ► Al–fly ash nano composites were produced by ultrasonic cavitation route. ► A homogeneous distribution of nano fly ash particles was observed in the matrix. ► No additional contamination in the nano composites from the atmosphere. ► Presence of nano fly ash leads to improvement in the strength of the composites. -- Abstract: In this paper an attempt has been made to modify the micro sized fly ash into nano structured fly ash using high energy ball mill. Ball milling was carried out for the total duration of 30 h. The sample was taken out after every 5 h of milling for characterizing. The nano structured fly ash was characterized for its crystallite size and lattice strain by using X-ray diffractometer. It was found that a steady decrease in the crystallite size and increased lattice strain was observed with milling time; the crystallite size at 30 h milling time was found to be 23 nm. The fresh fly ash particles are mostly spherical in shape; whereas the shape of the 30 h milled fly ash particles is irregular and the surface morphology is rough. Al–fly ash nano composites were produced by ultrasonic cavitation route successfully. Scanning electron microscopy images of nano composites reveal a homogeneous distribution of the nano fly ash particles in the AA 2024 matrix. Energy dispersive spectroscopy analysis of nano composites reveals that the fabricated nano composite did not contain any additional contamination from the atmosphere. As the amount of nano fly ash is increasing the hardness of the composite also increasing. The nano fly ash addition leads to improvement in the compression strength of the composites.

  6. 水热活化法提取粉煤灰中的氧化铝%Extracting alumina from fly ash by hydrothermal activation method

    Institute of Scientific and Technical Information of China (English)

    董宏; 张文广

    2014-01-01

    The pre-fired fly ash was dissolved with sodium hydroxide by the high-pressure hydrothermal acti-vation method .The influence factors on the dissolution rate of alumina were discussed , including the mole ratio of calcium to silicon , alkali concentration , the ratio of solid to liquid , caustic ratio , reaction temperature , reaction time, etc.Considering the dissolution rate of alumina , reaction cost and others, the optimum conditions of alumina dissolution were recognized .The results show that under condition of alkali-soluble the best experimental parame-ters include the ratio of calcium silicon molar as 1.0, the alkali concentration as 350 g/L, the ratio of solid to liq-uid as 10∶1, the caustic ratio 14, the reaction temperature as 280℃, and with the activation time of 2 h.Through optimizing the conditions of alumina dissolution process , the alumina extraction could reach more than 95% in ratio.%采用高压水热活化法对预先烧制的粉煤灰进行碱溶实验,探讨钙硅摩尔比、碱液浓度、液固比、苛性比、反应温度、反应时间等影响因素对于氧化铝溶出率的影响。考虑到氧化铝溶出率及反应成本等各方面因素,得出氧化铝溶出的适宜条件。结果表明:碱溶条件下,钙硅摩尔比为1.0,溶液碱浓度为350 g/L,液固比为10∶1,苛性比为14,反应温度280℃,活化时间为2 h。通过氧化铝溶出工艺条件的优化,可使氧化铝提取率达到95%以上。

  7. Synthesis and characterization of zeolites prepared from industrial fly ash.

    Science.gov (United States)

    Franus, Wojciech; Wdowin, Magdalena; Franus, Małgorzata

    2014-09-01

    In this paper, we present the possibility of using fly ash to produce synthetic zeolites. The synthesis class F fly ash from the Stalowa Wola SA heat and power plant was subjected to 24 h hydrothermal reaction with sodium hydroxide. Depending on the reaction conditions, three types of synthetic zeolites were formed: Na-X (20 g fly ash, 0.5 dm(3) of 3 mol · dm(-3) NaOH, 75 °C), Na-P1 (20 g fly ash, 0.5 dm(3) of 3 mol · dm(-3) NaOH, 95 °C), and sodalite (20 g fly ash, 0.8 dm(3) of 5 mol · dm(-3) NaOH + 0.4 dm(3) of 3 mol · dm(-3) NaCl, 95 °C). As synthesized materials were characterized to obtain mineral composition (X-ray diffractometry, Scanning electron microscopy-energy dispersive spectrometry), adsorption properties (Brunauer-Emmett-Teller surface area, N2 isotherm adsorption/desorption), and ion exchange capacity. The most effective reaction for zeolite preparation was when sodalite was formed and the quantitative content of zeolite from X-ray diffractometry was 90 wt%, compared with 70 wt% for the Na-X and 75 wt% for the Na-P1. Residues from each synthesis reaction were the following: mullite, quartz, and the remains of amorphous aluminosilicate glass. The best zeolitic material as characterized by highest specific surface area was Na-X at almost 166 m(2) · g(-1), while for the Na-P1 and sodalite it was 71 and 33 m(2) · g(-1), respectively. The ion exchange capacity decreased in the following order: Na-X at 1.8 meq · g(-1), Na-P1 at 0.72 meq · g(-1), and sodalite at 0.56 meq · g(-1). The resulting zeolites are competitive for commercially available materials and are used as ion exchangers in industrial wastewater and soil decontamination. PMID:24838802

  8. Workability and strength of coarse high calcium fly ash geopolymer

    Energy Technology Data Exchange (ETDEWEB)

    P. Chindaprasirt; T. Chareerat; V. Sirivivatnanon [Khon Kaen University, Khon Kaen (Thailand). Department of Civil Engineering

    2007-03-15

    In this paper, the basic properties viz., workability and strength of geopolymer mortar made from coarse lignite high calcium fly ash were investigated. The geopolymer was activated with sodium hydroxide (NaOH), sodium silicate and heat. The results revealed that the workable flow of geopolymer mortar was in the range of 110 {+-}5%-135 {+-}5% and was dependent on the ratio by mass of sodium silicate to NaOH and the concentration of NaOH. The obtained compressive strength was in the range of 10-65 MPa. The optimum sodium silicate to NaOH ratio to produce high strength geopolymer was 0.67-1.0. The concentration variation of NaOH between 10 M and 20 M was found to have a small effect on the strength. The geopolymer samples with high strength were obtained with the following practices: the delay time after moulding and before subjecting the sample to heat was 1 h and the optimum curing temperature in the oven was 75{sup o}C with the curing duration of not less than two days.

  9. Fly ash-based geopolymer lightweight concrete using foaming agent.

    Science.gov (United States)

    Al Bakri Abdullah, Mohd Mustafa; Hussin, Kamarudin; Bnhussain, Mohamed; Ismail, Khairul Nizar; Yahya, Zarina; Razak, Rafiza Abdul

    2012-01-01

    In this paper, we report the results of our investigation on the possibility of producing foam concrete by using a geopolymer system. Class C fly ash was mixed with an alkaline activator solution (a mixture of sodium silicate and NaOH), and foam was added to the geopolymeric mixture to produce lightweight concrete. The NaOH solution was prepared by dilute NaOH pellets with distilled water. The reactives were mixed to produce a homogeneous mixture, which was placed into a 50 mm mold and cured at two different curing temperatures (60 °C and room temperature), for 24 hours. After the curing process, the strengths of the samples were tested on days 1, 7, and 28. The water absorption, porosity, chemical composition, microstructure, XRD and FTIR analyses were studied. The results showed that the sample which was cured at 60 °C (LW2) produced the maximum compressive strength for all tests, (11.03 MPa, 17.59 MPa, and 18.19 MPa) for days 1, 7, and 28, respectively. Also, the water absorption and porosity of LW2 were reduced by 6.78% and 1.22% after 28 days, respectively. The SEM showed that the LW2 sample had a denser matrix than LW1. This was because LW2 was heat cured, which caused the geopolymerization rate to increase, producing a denser matrix. However for LW1, microcracks were present on the surface, which reduced the compressive strength and increased water absorption and porosity.

  10. Durability Study on High Calcium Fly Ash Based Geopolymer Concrete

    Directory of Open Access Journals (Sweden)

    Ganesan Lavanya

    2015-01-01

    Full Text Available This study presents an investigation into the durability of geopolymer concrete prepared using high calcium fly ash along with alkaline activators when exposed to 2% solution of sulfuric acid and 5% magnesium sulphate for up to 45 days. The durability was also assessed by measuring water absorption and sorptivity. Ordinary Portland cement concrete was also prepared as control concrete. The grades chosen for the investigation were M20, M40, and M60. The alkaline solution used for present study is the combination of sodium silicate and sodium hydroxide solution with the ratio of 2.50. The molarity of sodium hydroxide was fixed as 12. The test specimens were 150×150×150 mm cubes, 100×200 mm cylinders, and 100×50 mm discs cured at ambient temperature. Surface deterioration, density, and strength over a period of 14, 28, and 45 days were observed. The results of geopolymer and ordinary Portland cement concrete were compared and discussed. After 45 days of exposure to the magnesium sulfate solution, the reduction in strength was up to 12% for geopolymer concrete and up to 25% for ordinary Portland cement concrete. After the same period of exposure to the sulphuric acid solution, the compressive strength decrease was up to 20% for geopolymer concrete and up to 28% for ordinary Portland cement concrete.

  11. Phosphorus Removal From Milkhouse Wastewater and Barnyard Runoff With Fly ash Amendments in Vegetative Filter Strips

    Science.gov (United States)

    Giri, S.; Richards, B. K.; Geohring, L. D.; Steenhuis, T. S.

    2005-12-01

    Vegetative filter strips (VFS) are commonly used to reduce agricultural pollutants such as phosphorus (P) present in milkhouse wastewater and barnyard runoff. Although VFS can sometimes efficiently remove P, water flow and P sorption in a VFS used for treating milkhouse wastewater and barnyard runoff were found to be erratic due to preferential flow and reduced soil infiltration capacity. Several possible amendments were tested for P immobilization potential in the laboratory, including wollastonite (calcium metasilicate) and fly ash from a coal-fired power plant. Fly ash demonstrated superior P immobilization potential, with a Langmuir adsorption isotherm capacity of 10 mg g.-1. Fly ash was placed in the wastewater holding tank and in flow channels of an actual VFS, resulting in reduction of test well water ortho-P to ug L-1 (ppb) levels. Fly ash was shown to act in three ways: P adsorption, precipitation of P as Apatite, and co-precipitation of P during hydrolysis of Fe and Al. However, during summer P concentrations in observation wells was observed to be much higher than the influent wastewater in the VFS, particularly near the preferential flow path. Measurements of dissolved organic carbon (DOC), iron and total phosphorus indicate enhanced microbial activities during summer. As a result, anaerobic biodegradation of organic matter plays a great role in releasing P, Fe and Mn from adsorbed sites. It is believed that certain components of DOC (such as hydrophilic, hydrophobic and neutrals) are formed during anaerobic biodegradation of organic matter present in water and the VFS. These DOC components may interact with iron, aluminum, manganese, calcium etc. present in soil resulting in the concomitant release of elements together with adsorbed P. A practical management approach to reducing P during summer may involve relocating the preferred wastewater flowpaths in the VFS, as well as fresh applications of fly ash to the new flowpaths in order to avoid the

  12. Biological responses of agricultural soils to fly-ash amendment.

    Science.gov (United States)

    Singh, Rajeev Pratap; Sharma, Bhavisha; Sarkar, Abhijit; Sengupta, Chandan; Singh, Pooja; Ibrahim, Mahamad Hakimi

    2014-01-01

    The volume of solid waste produced in the world is increasing annually, and disposing of such wastes is a growing problem. Fly ash (FA) is a form of solid waste that is derived from the combustion of coal. Research has shown that fly ash may be disposed of by using it to amend agricultural soils. This review addresses the feasibility of amending agricultural field soils with fly ash for the purpose of improvings oil health and enhancing the production of agricultural crops. The current annual production of major coal combustion residues (CCRs) is estimated to be -600 million worldwide, of which about 500 million t (70-80%) is FA (Ahmaruzzaman 2010). More than 112 million t of FA is generated annually in India alone, and projections show that the production (including both FA and bottom ash) may exceed 170 million t per annum by 2015 (Pandey et al. 2009; Pandey and Singh 20 I 0). Managing this industrial by-product is a big challenge, because more is produced each year, and disposal poses a growing environmental problem.Studies on FA clearly shows that its application as an amendment to agricultural soils can significantly improve soil quality, and produce higher soil fertility. What FA application method is best and what level of application is appropriate for any one soil depends on the following factors: type of soil treated, crop grown, the prevailing agro climatic condition and the character of the FA used. Although utilizing FA in agricultural soils may help address solid waste disposal problems and may enhance agricultural production, its use has potential adverse effects also. In particular, using it in agriculture may enhance amounts of radionuclides and heavy metals that reach soils, and may therefore increase organism exposures in some instances. PMID:24984834

  13. Comparative performance of geopolymers made with metakaolin and fly ash after exposure to elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Daniel L.Y. Kong; Jay G. Sanjayan; Kwesi Sagoe-Crentsil [Monash University, Clayton, Vic. (Australia). Department of Civil Engineering

    2007-12-15

    This paper presents the results of a study on the effect of elevated temperatures on geopolymers manufactured using metakaolin and fly ash of various mixture proportions. Both types of geopolymers (metakaolin and fly ash) were synthesized with sodium silicate and potassium hydroxide solutions. The strength of the fly ash-based geopolymer increased after exposure to elevated temperatures (800{sup o}C). However, the strength of the corresponding metakaolin-based geopolymer decreased after similar exposure. Both types of geopolymers were subjected to thermogravimetric, scanning electron microscopy and mercury intrusion porosimetry tests. The paper concludes that the fly ash-based geopolymers have large numbers of small pores which facilitate the escape of moisture when heated, thus causing minimal damage to the geopolymer matrix. On the other hand, metakaolin geopolymers do not possess such pore distribution structures. The strength increase in fly ash geopolymers is also partly attributed to the sintering reactions of un-reacted fly ash particles.

  14. Effect of fly ash preliminary calcination on the properties of geopolymer.

    Science.gov (United States)

    Temuujin, J; van Riessen, A

    2009-05-30

    The influence of preliminary calcination of fly ashes on the geopolymerisation process has been studied. Preliminary calcination at 500 and 800 degrees C causes decarbonation of the fly ash while it also leads to a decrease of the amorphous content of the fly ashes from 60 to 57%. Geopolymer prepared using raw fly ash exhibited a compressive strength 55.7(9.2)MPa, while for 500 and 800 degrees C calcined samples it reduced to 54(5.8) and 44.4(5.4)MPa, respectively. The decrease in compressive strength of the geopolymers is discussed in terms of partial surface crystallisation of the fly ash particles. Reactivity of the fly ash also has been correlated with the shrinkage rate and presence of efflorescence on the surface of geopolymers.

  15. Relation between silico-aluminous fly ash and its coal of origin

    Institute of Scientific and Technical Information of China (English)

    Jean-Charles Benezet; Pierre Adamiec; Ali Benhassaine

    2008-01-01

    Fly ashes are typical complex solids which incorporate at the same time intrinsic properties derived from the layers (various mineralogical and dimensional spectra) and major transformations generated during prior processing. To use fly ashes in various applications, it is necessary to characterise them completely. The first research to date carried out on silico-aluminous fly ashes in order to characterise them physically,morphologically, chemically and mineralogically, resulted in the recognition that they are relatively simple materials. In the present study, a silico-aluminous fly ash coming from the power station of Albi (France) was selected. Heat treatment at 450 and 1200 ~C together with coal simulated the treatment undergone by coal in the power station in order to mimic real coal residue. In conclusion, the diversity of the particles contained in fly ash could only be explained by the relation existing between the fly ash and its coal of origin.

  16. Relationship between Structural Characteristics of Fly Ash and Reactivity under Autoclave Curing

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The reactivity of autoclaved materials is conventionally estimated by their chemical composition. In this paper, after determining the chemical composition of various types of fly ash, a series of new tests which included X-ray Diffraction (XRD), infrared spectral analysis (IR) and bound water testing, were applied to investigate the performance of autoclaved fly ash products. The relationship between the infrared spectral analysis of Si-O wavenumber (about 1 100 cm-1) and its autoclaved chemical reactivity, and compressive strength of its autoclaved samples, is analyzed. The results show that fly ash with a lower wavenumber will have stronger autoclaved chemical reactivity and higher compressive strength for its autoclaved sample. Thus, the Si-O stretching vibration wavelength can be used to estimate autoclaved chemical reactivity of fly ash, so as to control the quality of fly ash to be autoclaved, and to predict the compressive strength of autoclaved fly ash products.

  17. Development of construction specifications and quality assurance criteria for compacted fly ash-cement feedlot pads

    Energy Technology Data Exchange (ETDEWEB)

    Kalinski, M.E.; Bicudo, J.R.; Hippley, B.; Nanduri, S.R. [University of Kentucky, Lexington, KY (United States). Dept. of Civil Engineering

    2005-05-01

    Numerous industrial uses have been identified for fly ash that economically benefits both the fly ash producer and the fly ash user. One such use is the construction of compacted fly ash-cement pads for hay storage and for livestock heavy traffic areas, including traffic lanes, feeding areas, watering sites, loafing lots, and feedlots. The use of a variety of pads (e.g. soil-cement, fly ash, geotextile-gravel) in feedlots has been shown to improve daily gain and reduce hoof disease in cattle. However quality assurance methods for construction of such pads are lacking. Therefore, a laboratory study was performed to develop a quantitative approach to construction quality assurance (CQA) testing of compacted fly ash-cement pads.

  18. Leaching Study in Immobilization of Cesium and Cobalt Radionuclides In Fly Ash- Zeolite Cement

    International Nuclear Information System (INIS)

    Fly ash-zeolite cement was synthesized from industrial by-product fly ash obtained from the thermal electric power station. The synthesis process is based on the hydrothermal-calcination-route of the fly ash. The microstructure of fly ash-zeolite cement was characterized by X-ray diffraction, FT infrared spectroscopy and surface area (F-N2). The efficiency of innovative matrices for immobilizing cesium and cobalt radionuclides is presented in this work. The aim of the present study is to investigate the possibility of solidifying 137Cs and 60Co radionuclides in synthetic fly ash zeolite cement. Leaching behavior of the radionuclides have been studied. The leachability index measured indicated that fly ash zeolite cement matrix can be utilized as an efficient material for immobilizing cesium and cobalt radionuclides than portland cement.

  19. Study on Type C Coal Fly ash as an Additive to Molding Sand for Steel Casting

    Science.gov (United States)

    Palaniappan, Jayanthi

    2016-05-01

    Study of physio-chemical properties studies such as granulometric analysis, moisture, X ray fluorescence etc. were performed with Type C coal—combustion fly ash to investigate their potential as a distinct option for molding sand in foundry, thereby reducing the dependency on latter. Technological properties study such as compressive strength, tensile strength, permeability and compaction of various compositions of fly ash molding sand (10, 20 and 30 % fly ash substitute to chemically bonded sand) were performed and compared with silica molding sand. Steel casting production using this fly ash molding sand was done and the casting surface finish and typical casting parameters were assessed. It was noted that a good quality steel casting could be produced using type C fly ash molding sand, which effectively replaced 20 % of traditional molding sand and binders thereby providing greater financial profits to the foundry and an effective way of fly ash utilization (waste management).

  20. Strontium isotopes as tracers of airborne fly ash from coal-fired power plants

    International Nuclear Information System (INIS)

    The paper presents the results of a controlled greenhouse experiment in which a native desert plant, the brittlebush was grown on admixtures of desert soils and fly ash. The fly ash is strongly enriched in Sr and the brittlebush is a Sr accumulator. The data demonstrate that the brittlebush isotopically equilibrates with desert soils whose fly ash components are as low as 0.25% by weight, the fly ash Sr is apparently more available to the plant than Sr derived from the soils, and the difference between the 87Sr/86Sr ratio of the fly ash (0.70807) and soils (0.71097 to 0.71117) warrants further investigations in the natural environment to determine the practicality of this method as a natural tracer of fly ash in the environment

  1. Effect of Fly Ash on Durability of High Performance Concrete Composites

    OpenAIRE

    Peng Zhang; Qingfu Li

    2013-01-01

    A parametric experimental study has been conducted to investigate the effect of fly ash on the durability of the concrete composites. Four different fly ash contents (10, 15, 20 and 25% respectively) were used. The durability of concrete composites includes water impermeability, dry shrinkage property, the carbonation resistance and the freeze-thaw resistance. The results indicate that the addition of fly ash has greatly improved the water impermeability and restricted the dry shrinkage of co...

  2. Characterisation and use of biomass fly ash in cement-based materials.

    Science.gov (United States)

    Rajamma, Rejini; Ball, Richard J; Tarelho, Luís A C; Allen, Geoff C; Labrincha, João A; Ferreira, Victor M

    2009-12-30

    This paper presents results about the characterisation of the biomass fly ashes sourced from a thermal power plant and from a co-generation power plant located in Portugal, and the study of new cement formulations incorporated with the biomass fly ashes. The study includes a comparative analysis of the phase formation, setting and mechanical behaviour of the new cement-fly ash formulations based on these biomass fly ashes. Techniques such as X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), thermal gravimetric and differential thermal analysis (TG/DTA), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and environmental scanning electron spectroscopy (ESEM) were used to determine the structure and composition of the formulations. Fly ash F1 from the thermal power plant contained levels of SiO(2), Al(2)O(3) and Fe(2)O(3) indicating the possibility of exhibiting pozzolanic properties. Fly ash F2 from the co-generation plant contained a higher quantity of CaO ( approximately 25%). The fly ashes are similar to class C fly ashes according to EN 450 on the basis of chemical composition. The hydration rate and phase formation are greatly dependant on the samples' alkali content and water to binder (w/b) ratio. In cement based mortar with 10% fly ash the basic strength was maintained, however, when 20% fly ash was added the mechanical strength was around 75% of the reference cement mortar. The fly ashes contained significant levels of chloride and sulphate and it is suggested that the performance of fly ash-cement binders could be improved by the removal or control of these chemical species.

  3. Synthesis of Faujasite from Fly Ash and its Applications for Hydrocracking of Petroleum Distillates

    OpenAIRE

    Sutarno Sutarno; Yateman Arryanto

    2007-01-01

    The synthesis of faujasite from fly ash and its application for hydrocracking catalyst of heavy petroleum distillates have been performed. Faujasite was synthesized from fly ash by hydrothermal reaction in alkaline solution via combination of reflux pretreatment of fly ash with HCl and fusion with NaOH. The preparation of nickel containing catalysts by ion exchange method under similar initial concentration of nickel resulted higher amount of nickel loaded on faujasite than those on ze...

  4. Permeation Properties and Pore Structure of Surface Layer of Fly Ash Concrete

    OpenAIRE

    Jun Liu; Qiwen Qiu; Feng Xing; Dong Pan

    2014-01-01

    This paper presents an experimental study on the nature of permeation properties and pore structure of concrete surface layers containing fly ash. Concretes containing different dosages of fly ash as a replacement for cement (15% and 30% by weight of total cement materials, respectively) were investigated. Concrete without any fly ash added was also employed as the reference specimen. Laboratory tests were conducted to determine the surface layer properties of concrete including chloride tran...

  5. Adsorption of Crystal Violet Dye from Aqueous Solution onto Zeolites from Coal Fly and Bottom Ashes

    OpenAIRE

    Tharcila Colachite Rodrigues Bertolini; Juliana C. Izidoro; Carina P. Magdalena; Denise A. Fungaro

    2013-01-01

    The adsorption of the cationic dye Crystal Violet (CV) over zeolites from coal fly ash (ZFA) and bottom ash (ZBA) was evaluated. The coal fly ash (CFA) and the coal bottom ash (CBA) used in the synthesis of the zeolites by alkaline hydrothermal treatment were collected in Jorge Lacerda coal-fired power plant located at Capivari de Baixo County, in Santa Catarina State, Brazil. The zeolitic materials were characterized predominantly as hydroxy-sodalite and X. The dye adsorption equilibrium was...

  6. Mineralogy and microstructure of sintered lignite coal fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Marina Ilic; Christopher Cheeseman; Christopher Sollars; Jonathan Knight [Faculty of Technology and Metallurgy, Belgrade (Yugoslavia)

    2003-02-01

    Lignite coal fly ash from the 'Nikola Tesla' power plant in Yugoslavia has been characterised, milled, compacted and sintered to form monolithic ceramic materials. The effect of firing at temperatures between 1130 and 1190{sup o}C on the density, water accessible porosity, mineralogy and microstructure of sintered samples is reported. This class C fly ash has an initial average particle size of 82 {mu}m and contains siliceous glass together with the crystalline phases quartz, anorthite, gehlenite, hematite and mullite. Milling the ash to an average particle size of 5.6 m, compacting and firing at 1170{sup o}C for 1 h produces materials with densities similar to clay-based ceramics that exhibit low water absorption. Sintering reduces the amount of glass, quartz, gehlenite and anhydrite, but increases formation of anorthite, mullite, hematite and cristobalite. SEM confirms the formation of a dense ceramic at 1170{sup o}C and indicates that pyroplastic effects cause pore formation and bloating at 1190{sup o}C. 23 refs., 6 figs., 2 tabs.

  7. Direct Quantitative Analysis of Arsenic in Coal Fly Ash

    Directory of Open Access Journals (Sweden)

    Sri Hartuti

    2012-01-01

    Full Text Available A rapid, simple method based on graphite furnace atomic absorption spectrometry is described for the direct determination of arsenic in coal fly ash. Solid samples were directly introduced into the atomizer without preliminary treatment. The direct analysis method was not always free of spectral matrix interference, but the stabilization of arsenic by adding palladium nitrate (chemical modifier and the optimization of the parameters in the furnace program (temperature, rate of temperature increase, hold time, and argon gas flow gave good results for the total arsenic determination. The optimal furnace program was determined by analyzing different concentrations of a reference material (NIST1633b, which showed the best linearity for calibration. The optimized parameters for the furnace programs for the ashing and atomization steps were as follows: temperatures of 500–1200 and 2150°C, heating rates of 100 and 500°C s−1, hold times of 90 and 7 s, and medium then maximum and medium argon gas flows, respectively. The calibration plots were linear with a correlation coefficient of 0.9699. This method was validated using arsenic-containing raw coal samples in accordance with the requirements of the mass balance calculation; the distribution rate of As in the fly ashes ranged from 101 to 119%.

  8. Thermal treatment of ashes[Fly Ash from Municipal Waste Incineration]; Termisk rening av askor

    Energy Technology Data Exchange (ETDEWEB)

    Wikman, Karin; Berg, Magnus; Bjurstroem, Henrik [AaF-Energi och Miljoe AB, Stockholm (Sweden); Nordin, Anders [Umeaa Univ. (Sweden). Dept. of Applied Physics and Electronics

    2003-04-01

    In this project descriptions of different processes for thermal treatment of ashes have been compiled. A technical and economic evaluation of the processes has been done to identify possibilities and problems. The focus in the project lays on treatment of fly ash from municipal waste incineration but the processes can also be used to treat other ashes. When the ash is heated in the thermal treatment reactor, with or without additives, the material is sintered or vitrified and at the same time volatile substances (Zn, Pb, Cd, Hg etc.) are separated. In general the separation is more effective in processes with reducing conditions compared to oxidizing conditions. Oxidizing processes have both worse separation capacity and require more energy. The oxidizing processes are mainly used to stabilize the ash through vitrification and they are in some cases developed for management of municipal sewage sludge and bottom ash. However, these processes are often not as complex as for example an electric arc melting furnace with reducing conditions. The research today aim to develop more effective electrical melting systems with reducing conditions such as plasma melting furnaces, electric resistance melting furnaces and low frequency induction furnaces. A central question in the evaluation of different thermal treatment processes for ash is how the residues from the treatment can be used. It is not certain that the vitrified material is stable enough to get a high economic value, but it can probably be used as construction material. How the remaining metals in the ash are bound is very important in a long-time perspective. Further studies with leaching tests are necessary to clarify this issue. The heavy metal concentrate from the processes contains impurities, such as chlorine, which makes it unprofitable to obtain the metals. Instead the heavy metal concentrate has to be land filled. However, the amount of material for land filling will be much smaller if only the heavy

  9. Elemental characterization of coal, fly ash, and bottom ash using an energy dispersive X-ray fluorescence technique

    International Nuclear Information System (INIS)

    A total of 18 elements viz. Si, Al, Fe, Ca, Mg, K, Na, Sr, V, Zn, Mn, Cr, Cu, Pb, Ni, Co, As and Cd were analyzed in coal, fly ash and bottom ash samples collected across India using an EDXRF technique. Various indices such as element enrichment ratio, enrichment factor (with respect to crustal average) and mineral composition were calculated. Around 95% of mass was reconstructed using the concentration of elements in this study for fly and bottom ash. - Highlights: • Concentrations of 18 elements were determined in coal and ash samples using EDXRF. • Mineral quantification up to 95% was carried out for fly and bottom ash samples. • Enrichment ratios of elements were calculated in combustion residue with respect to coal. • Enrichment factor with respect to crustal average was estimated for ash samples

  10. Environmental impact of manganese due to its leaching from coal fly ash.

    Science.gov (United States)

    Prasad, Bably; Mondal, Kajal K R

    2009-01-01

    In India, so far not much efforts have been made to use coal ash as backfill material in underground/ open cast mines and to predict its subsequent effect on ground water quality. One of the main problems in disposing of big quantities of coal ash is the possible leaching of different pollutants, including manganese. A thorough investigation regarding leaching of manganese from different fly ashes is required to know the impact of manganese due to its leaching from fly ash to ground water as well as surface water. In the present study, short term and long term leaching studies have been carried out on fly ash, bottom ash, pond ash and weathered ash of Chandrapura thermal power plant, Bokaro, Jharkhand and Ramagundam thermal power plant, Ramagundam, Andhra Pradesh. The amount of manganese released in different experiments has been evaluated. The leachate of Chandrapura fly ash has more manganese concentration (0.2001 mg/L) than the leachate of bottom ash, pond ash and weathered ash. A field investigation at Damoda abandoned open cast mine, filled with pond ash of Chandrapura thermal power plant revealed that concentration of manganese in ground water beneath the ash filled mine has been found very high (maximum up to 6.0 mg/L). But its migration to a long distance has not been seen. Remedial measures for coal ash disposal have also been formulated.

  11. Thermochemical Formation of Polybrominated Dibenzo-p-Dioxins and Dibenzofurans Mediated by Secondary Copper Smelter Fly Ash, and Implications for Emission Reduction.

    Science.gov (United States)

    Wang, Mei; Liu, Guorui; Jiang, Xiaoxu; Zheng, Minghui; Yang, Lili; Zhao, Yuyang; Jin, Rong

    2016-07-19

    Heterogeneous reactions mediated by fly ash are important to polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/Fs) formation. However, the formation of polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) through heterogeneous reactions is not yet well understood. Experiments were performed to investigate the thermochemical formation of PBDD/Fs at 150-450 °C through heterogeneous reactions on fly ash from a secondary copper smelter. The maximum PBDD/F concentration was 325 times higher than the initial PBDD/F concentration in the fly ash. The PBDD/F concentration after the experiment at 150 °C was five times higher than the initial concentration. PBDD/Fs have not previously been found to form at such a low temperature. Secondary-copper-smelter fly ash clearly promoted PBDD/F formation, and this conclusion was supported by the low activation energies that were found in Arrhenius's law calculations. Thermochemical formation of PBDD/Fs mediated by fly ash deposited in industrial facilities could explain "memory effects" that have been found for PCDD/Fs and similar compounds released from industrial facilities. Abundant polybrominated diphenyl ethers (PBDEs) that were formed through fly ash-mediated reactions could be important precursors for PBDD/Fs also formed through fly ash-mediated reactions. The amounts of PBDEs that formed through fly ash-mediated reactions suggested that secondary copper smelters could be important sources of reformed PBDEs. PMID:27347728

  12. Fly ash grouts for remediation of acid mine drainage

    International Nuclear Information System (INIS)

    An engineering investigation into the use of electric utility wastes for grouting acidic mine spoil resulting from coal extraction has been undertaken. Laboratory investigations into the physical and chemical properties of various grout mixtures and grouted spoil materials are underway. Grout mixtures are placed in columns and permeated with distilled water. The hydraulic conductivity of the grout was measured. The effect of the high alkaline ashes on the acidic drainage is of particular interest. This series of experiments provided information so that the most favorable grout (low hydraulic conductivity and high alkalinity) could be selected for injection into acidic spoil material. Both standard combustion and fluidized bed ashes were tested. Grout mixtures include ashes, scrubber sludge, lime, bentonite and/or kaolinite. Permeabilities of the mixtures averaged approximately 1.OE-4 cm/sec. A second series of laboratory experiments consists of grouting large diameter drums of acidic spoil with the fly ash grouts. The drums have been constructed and filled with acidic spoil material. The ungrouted infiltration rates have been determined and the resulting effluents chemically analyzed

  13. Synthesis of merlinoite from Chinese coal fly ashes and its potential utilization as slow release K-fertilizer.

    Science.gov (United States)

    Li, Jing; Zhuang, Xinguo; Font, Oriol; Moreno, Natalia; Vallejo, V Ramon; Querol, Xavier; Tobias, Aurelio

    2014-01-30

    This study focuses on the synthesis of merlinoite from Chinese coal fly ashes by KOH direct conversion method, with special emphasis on the application of synthetic merlinoite as fertilizer. These fly ashes were collected from two pulverized-coal combustion (PCC) power plants in Xinjiang, Northwest China. The synthesis results are influenced by fly ash characteristics and different synthesis conditions (KOH solution concentrations, activation temperature, time, and KOH/fly ash ratios). A high quality merlinoite-rich product was synthesized under optimal activation conditions (KOH concentration of 5M, activation temperature of 150°C, activation time of 8h and KOH/fly ash ratio of 2l/kg), with a cation exchange capacity (CEC) of 160cmolkg(-1). The synthetic merlinoite is proved to be an efficient slow release K-fertilizer for plant growth, indicating that it can be widely used for high-nutrient demanding crops growing in nutrient-limited soils and for large-area poor soil amendment in opencast coal mine areas around the power plants that will substantially grow with the increasing coal combustion in Xinjiang in the near future. PMID:24365875

  14. Chlorides behavior in raw fly ash washing experiments

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Fenfen, E-mail: zhu@hse.gcoe.kyoto-u.ac.jp [Department of Urban and Environmental Engineering, Graduate School of Engineering, Katsura Campus, Kyoto University, Nishikyo-ku, Kyoto 615-8540 (Japan); Takaoka, Masaki; Oshita, Kazuyuki [Department of Urban and Environmental Engineering, Graduate School of Engineering, Katsura Campus, Kyoto University, Nishikyo-ku, Kyoto 615-8540 (Japan); Kitajima, Yoshinori; Inada, Yasuhiro [High Energy Accelerator Research Organization (KEK), Institute of Material Structure Science (IMSS), Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan); Morisawa, Shinsuke; Tsuno, Hiroshi [Department of Urban and Environmental Engineering, Graduate School of Engineering, Katsura Campus, Kyoto University, Nishikyo-ku, Kyoto 615-8540 (Japan)

    2010-06-15

    Chloride in fly ash from municipal solid waste incinerators (MSWIs) is one of the obstructive substances in recycling fly ash as building materials. As a result, we have to understand the behavior of chlorides in recycling process, such as washing. In this study, we used X-ray absorption near edge structure (XANES) and X-ray diffraction (XRD) to study the chloride behavior in washed residue of raw fly ash (RFA). We found that a combination of XRD and XANES, which is to use XRD to identify the situation of some compounds first and then process XANES data, was an effective way to explain the chlorides behavior in washing process. Approximately 15% of the chlorine in RFA was in the form of NaCl, 10% was in the form of KCl, 51% was CaCl{sub 2}, and the remainder was in the form of Friedel's salt. In washing experiments not only the mole percentage but also the amount of soluble chlorides including NaCl, KCl and CaCl{sub 2} decreases quickly with the increase of liquid to solid (L/S) ratio or washing frequency. However, those of insoluble chlorides decrease slower. Moreover, Friedel's salt and its related compound (11CaO.7Al{sub 2}O{sub 3}.CaCl{sub 2}) were reliable standards for the insoluble chlorides in RFA, which are strongly related to CaCl{sub 2}. Washing of RFA promoted the release of insoluble chlorides, most of which were in the form of CaCl{sub 2}.

  15. Electrodialytic removal of cadmium from biomass combustion fly ash in larger scale

    DEFF Research Database (Denmark)

    Pedersen, Anne Juul; Ottosen, Lisbeth M.; Simonsen, Peter;

    2005-01-01

    Due to a high concentration of the toxic heavy metal cadmium (Cd), biomass combustion fly ash often fails to meet the Danish legislative requirements for recycling on agricultural fields. It has previously been shown that it is possible to reduce the concentration of Cd in different bio ashes......). The experimental ash was a straw combustion fly ash suspended in water. Within 4 days of remediation, Cd concentrations below the limiting concentration of 5.0 mg Cd/kg DM for straw ash were reached. On the basis of these results, the energy costs for remediation of ash in industrial scale have been estimated...

  16. REMOVAL OF REACTIVE DYE WITH FLY ASH ADSORPTION

    OpenAIRE

    EREN, Zeynep; Filiz Nuran ACAR

    2004-01-01

    The efectiveness of fly ash in adsorbing Chemactive D Black N from aqueous solutions has been studied as a function adsorbent dosage and initial dye concentration. The Langmuir adsorption ishoterm were found more suitable than Freundlich isotherm. The adsorption capacity Q o was 6.75 mg/g at natural initial pH (pH = 5.40). The removal ratio of dye respectively founded % 100, % 98, % 98, % 82.5, % 66.31 at 5, 10, 25, 50 and 100 mg/L initial dye concentration.

  17. Studies of the adsorption thermodynamics of oxamyl on fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Singh, D. [Government Postgraduate School, Sawai Madhopur (India). Faculty of Agriculture, Dept. of Soil Science

    2000-07-01

    The adsorption thermodynamics of oxamyl on fly ash at 10, 25 and 50{degree}C have been studied via the relevant adsorption isotherms, Freundlich constants, distribution coefficient and other thermodynamic parameters. The data were well fitted by the Freundlich equation and yielded S-shaped isotherms at all the temperatures studied. Thermodynamic parameters such as the thermodynamic equilibrium constant, the standard free energy change, the standard enthalpy change and the standard entropy change have been calculated as a means of predicting the nature of the adsorption process.

  18. REMOVAL OF REACTIVE DYE WITH FLY ASH ADSORPTION

    Directory of Open Access Journals (Sweden)

    Zeynep EREN

    2004-02-01

    Full Text Available The efectiveness of fly ash in adsorbing Chemactive D Black N from aqueous solutions has been studied as a function adsorbent dosage and initial dye concentration. The Langmuir adsorption ishoterm were found more suitable than Freundlich isotherm. The adsorption capacity Q o was 6.75 mg/g at natural initial pH (pH = 5.40. The removal ratio of dye respectively founded % 100, % 98, % 98, % 82.5, % 66.31 at 5, 10, 25, 50 and 100 mg/L initial dye concentration.

  19. Mechanical and microstructural characterization of geopolymer synthesized from low calcium fly ash

    Directory of Open Access Journals (Sweden)

    Kramar Sabina

    2015-01-01

    Full Text Available This study deals with the mechanical and microstructural characterization of geopolymers synthesized from locally available fly ash. A low calcium fly ash was activated using a sodium silicate solution. Samples were characterized by means of flexural and compressive tests, Fourier Transform Infrared (FTIR spectroscopy, X-ray powder diffraction (XRD, and scanning electron microscopy (SEM. Porosity and pore size distributions were identified using mercury intrusion porosimetry and gas sorption. The compressive strength of the produced geopolymers, which is in the range of 1.6 to 53.3 N/mm2, is strongly related to the water content as well as SiO2/Na2O mass ratio of an alkali activator. The compressive strength significantly increased with decreases in the water content and increased silicon concentration used for the synthesis of geopolymers.

  20. Utilization of washed MSWI fly ash as partial cement substitute with the addition of dithiocarbamic chelate.

    Science.gov (United States)

    Gao, Xingbao; Wang, Wei; Ye, Tunmin; Wang, Feng; Lan, Yuxin

    2008-07-01

    The management of the big amount of fly ash as hazardous waste from the municipal solid waste incinerator (MSWI) has encountered many problems in China. In this study, a feasibility research on MSWI fly ash utilization as partial cement substitute in cement mortars was therefore carried out. MSWI fly ash was subjected to washing process to reduce its chlorine content (from 10.16% to 1.28%). Consequently, it was used in cement mortars. Ten percent and 20% replacement of cement by washed ash showed acceptable strength properties. In TCLP and 180-day monolithic tests, the mortars with washed ash presented a little stronger heavy metal leachability, but this fell to the blank level (mortar without washed ash) with the addition of 0.25% chelate. Therefore, this method is proposed as an environment-friendly technology to achieve a satisfactory solution for MSWI fly ash management.

  1. Influences of Fly Ash on Concrete Product's Properties and Environmental Impact Reduction

    Directory of Open Access Journals (Sweden)

    Thipsuree Kornboonraksa

    2015-01-01

    Full Text Available This research aimed to study effects of incorporating fly ash into concrete products. Scope of this study were (1 hazard identification of fly ash (2 study on standard testing of various concrete products and (3 study on environmental impact assessment of concrete products mixed with fly ash. Various types of fly ash namely A, B, C and D were sampling from different power plants. Hazard identification of fly ash was analyzed in terms of total threshold limit concentration (TTLC and soluble threshold limit concentration (STLC. It was found that concentrations of chromium, cadmium, lead, mercury, nickel, zinc, copper and arsenic passed the criteria of notification of the ministry of industry regarding disposal of wastes or unusable materials B.E. 2548 (2005 in appendix-2.Three types of concrete products namely brick road, concrete block and ready mixed concrete were studied. Fly ash was used as cementitious materials to replace Portland cement at 10% and 30% mixture. Concrete products with proportion of fly ash showed lower compressive strengths during 28 days of curing times. However, increase of curing times showed higher compressive strengths for all types of concrete products. ANOVA analysis showed that different fly ash proportion and curing times had a significant effect on compressive strength. The method of CML2 baseline 2000, SimaPro 7.3 was used in environmental impact assessment. The functional unit was set up through working area of 1 m3. It was found that concrete products mixed with fly ash showed lower environmental impact compared to concrete products without fly ash. Increasing proportion of fly ash showed decreased environmental impact. From ANOVA analysis, there was no significant effect of fly ash types on environmental impact reduction for all types of concrete products. However, % fly ash mixture showed significant effect on environmental impact reduction especially in terms of global warming. Decrease in global warming (GW

  2. Synthesis and Heavy Metal Immobilization Behaviors of Fly Ash based Gepolymer

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yunsheng; SUN Wei; SHE Wei; SUN Guowei

    2009-01-01

    Two aspects of studies were carried out:1)synthesis of geopolymer by using fly ash and metakaolin;2)Immobilization behaviors of fly ash based geopolymer in a presence of Pb and Cu ions.As for the synthesis of fly ash based geopolymer,4 different fly ash content(10%,30%, 50%,70%)and 3 types of curing regimes(standard curing,steam curing and autoclave curing)were investigated to obtain the optimum synthesis condition based on the compressive and flexural strength.The experimental results show that geopolymer,containing 30%fly ash and synthesized at steam curing(80℃ for 8 h),exhibits higher mechanical strengths.The compressive and flexural strengths of fly ash based geopolymer reach 32.2 Mpa and 7.15 Mpa,respectively.Additionally,In-frared (IR) and X-ray diffraction(XRD)techniques were used to characterize the microstructure of the fly ash geopolymer.IR spectra shows that the absorptive band at 1086 cm ~(-1) shifts to lower wave number around 1033 cm ~(-1) ,and the 6-coordinated Al transforms into 4-coordination during the syn-thesis of fly ash based geopolymer.The resulting geopolymeric products were X-ray amorphous ma-terials.As for immobilization of heavy metals,the leaching tests were employed to investigate the immobilization behaviors of the fly ash based geopolymer synthesized under the above optimum condition.The leaching tests showed that fly ash based geopolymer can effectively immobilize Cu and Pb heavy metal ions,and the immobilization efficiency reached 90% greater when heavy metals were incorporated in the fly ash geopolymer in the range of 0.1% to 0.3%.The Pb exhibits better immobilization efficiency than the Cu,especially in the case of large dosages of heavy metals.

  3. On the removal of hexavalent chromium from a Class F fly ash.

    Science.gov (United States)

    Huggins, F E; Rezaee, M; Honaker, R Q; Hower, J C

    2016-05-01

    Coarse and fine samples of a Class F fly ash obtained from commercial combustion of Illinois bituminous coal have been exposed to two long-term leaching tests designed to simulate conditions in waste impoundments. ICP-AES analysis indicated that the coarse and fine fly ash samples contained 135 and 171mg/kg Cr, respectively. Measurements by XAFS spectroscopy showed that the ash samples originally contained 5 and 8% of the chromium, respectively, in the hexavalent oxidation state, Cr(VI). After exposure to water for more than four months, the percentage of chromium as Cr(VI) in the fly-ash decreased significantly for the coarse and fine fly-ash in both tests. Combining the XAFS data with ICP-AES data on the concentration of chromium in the leachates indicated that, after the nineteen-week-long, more aggressive, kinetic test on the coarse fly ash, approximately 60% of the Cr(VI) had been leached, 20% had been reduced to Cr(III) and retained in the ash, and 20% remained as Cr(VI) in the ash. In contrast, during the six-month-long baseline test, very little Cr was actually leached from either the coarse or the fine fly-ash (<0.1mg/kg); rather, about 66% and 20%, respectively, of the original Cr(VI) in the coarse and fine fly-ash was retained in the ash in that form, while the remainder, 34% and 80%, respectively, was reduced and retained in the ash as Cr(III). The results are interpreted as indicating that Cr(VI) present in Class F fly-ash can be reduced to Cr(III) when in contact with water and that such chemical reduction can compete with physical removal of Cr(VI) from the ash by aqueous leaching. PMID:26951722

  4. PERFORMANCE OF ALKALI-ACTIVATED PHOSPHOR SLAG-FLY ASH CEMENT AND THE MICROSTRUCTURE OF ITS HARDENED PASTE%碱-磷渣-粉煤灰胶凝材料的性能与硬化浆体结构

    Institute of Scientific and Technical Information of China (English)

    方永浩; 毛哲军; 王成; 朱琦

    2007-01-01

    The performance of alkali-activated phosphor slag-fly ash cement with different phosphor slag/fly ash proportions was studied, and the pore and microstructure of the hardened pastes were analyzed by mercury intrusion porosimetry and scanning electron microscope. The results show that alkali-activated phosphor slag cement has normal setting performance, which is different from that of alkali-activated blast furnace slag cement. The compressive strengths of the cement at 3 d and 28 d reach as high as 30.9 MPa and 98.8 MPa, respectively, and the flexural strengths are lower compared with ordinary portland cement. Adding 0-30% (in mass)fly ash into the alkali-phosphor slag system will slightly increase the setting time, however it will reduce the compressive strength,and improve the flexural strength. The corrosion resistance and freeze/thaw resistance of alkali-activated cement are much better, and the drying shrinkage rate is much greater than ordinary portland cement. Substituting phosphor slag partly with fly ash reduces the drying shrinkage to some extent. The hardened alkali-activated phosphor slag-fly ash cement paste is very dense due to very low porosity and a small mean pore diameter.%为充分利用磷渣和粉煤灰两种工业废渣生产高性能胶凝材料,研究了不同磷渣/粉煤灰配合比的碱-磷渣-粉煤灰胶凝材料性能,并用扫描电子显微镜和压汞仪分析了硬化浆体的细观结构和孔结构.结果表明:碱-磷渣-粉煤灰胶凝材料的凝结时间正常,在粉煤灰掺量为0~30 %(质量分数)范围内,随粉煤灰的掺量的增加,碱-磷渣-粉煤灰胶凝材料的凝结时间略有延长.与普通硅酸盐水泥相比,碱-磷渣胶凝材料的抗压强度较高,其3d和28d抗压强度分别可达到30.9MPa和98.8MPa,但其抗折强度相对较低.掺加粉煤灰后碱胶凝材料的抗压强度降低,而抗折强度提高.碱-磷渣-粉煤灰胶凝材料的耐蚀性和抗冻性能均显著优于硅酸盐水

  5. Fly Ash-based Geopolymer Lightweight Concrete Using Foaming Agent

    Directory of Open Access Journals (Sweden)

    Rafiza Abdul Razak

    2012-06-01

    Full Text Available In this paper, we report the results of our investigation on the possibility of producing foam concrete by using a geopolymer system. Class C fly ash was mixed with an alkaline activator solution (a mixture of sodium silicate and NaOH, and foam was added to the geopolymeric mixture to produce lightweight concrete. The NaOH solution was prepared by dilute NaOH pellets with distilled water. The reactives were mixed to produce a homogeneous mixture, which was placed into a 50 mm mold and cured at two different curing temperatures (60 °C and room temperature, for 24 hours. After the curing process, the strengths of the samples were tested on days 1, 7, and 28. The water absorption, porosity, chemical composition, microstructure, XRD and FTIR analyses were studied. The results showed that the sample which was cured at 60 °C (LW2 produced the maximum compressive strength for all tests, (11.03 MPa, 17.59 MPa, and 18.19 MPa for days 1, 7, and 28, respectively. Also, the water absorption and porosity of LW2 were reduced by 6.78% and 1.22% after 28 days, respectively. The SEM showed that the LW2 sample had a denser matrix than LW1. This was because LW2 was heat cured, which caused the geopolymerization rate to increase, producing a denser matrix. However for LW1, microcracks were present on the surface, which reduced the compressive strength and increased water absorption and porosity.

  6. Fly ash-based geopolymer lightweight concrete using foaming agent.

    Science.gov (United States)

    Al Bakri Abdullah, Mohd Mustafa; Hussin, Kamarudin; Bnhussain, Mohamed; Ismail, Khairul Nizar; Yahya, Zarina; Razak, Rafiza Abdul

    2012-01-01

    In this paper, we report the results of our investigation on the possibility of producing foam concrete by using a geopolymer system. Class C fly ash was mixed with an alkaline activator solution (a mixture of sodium silicate and NaOH), and foam was added to the geopolymeric mixture to produce lightweight concrete. The NaOH solution was prepared by dilute NaOH pellets with distilled water. The reactives were mixed to produce a homogeneous mixture, which was placed into a 50 mm mold and cured at two different curing temperatures (60 °C and room temperature), for 24 hours. After the curing process, the strengths of the samples were tested on days 1, 7, and 28. The water absorption, porosity, chemical composition, microstructure, XRD and FTIR analyses were studied. The results showed that the sample which was cured at 60 °C (LW2) produced the maximum compressive strength for all tests, (11.03 MPa, 17.59 MPa, and 18.19 MPa) for days 1, 7, and 28, respectively. Also, the water absorption and porosity of LW2 were reduced by 6.78% and 1.22% after 28 days, respectively. The SEM showed that the LW2 sample had a denser matrix than LW1. This was because LW2 was heat cured, which caused the geopolymerization rate to increase, producing a denser matrix. However for LW1, microcracks were present on the surface, which reduced the compressive strength and increased water absorption and porosity. PMID:22837687

  7. Thermal behaviour of geopolymers prepared using class F fly ash and elevated temperature curing

    Energy Technology Data Exchange (ETDEWEB)

    T. Bakharev [Monash University, Clayton, Vic. (Australia). Department of Civil Engineering

    2006-06-15

    This article reports a study of thermal stability of properties upon firing at 800-1200{sup o}C of geopolymer materials prepared using class F fly ash and Na and K alkaline activators. Compressive strength and shrinkage measurements, XRD, SEM (BEI), TGA and MIP were utilised in these studies. The materials were prepared at water/binder ratios in a range of 0.09-0.35, using compaction pressures up to 10 MPa and curing temperatures 80 and 100{sup o}C. Thermal stability of the studied geopolymer materials was rather low. In the samples prepared using sodium-containing activators rapid deterioration of strength at 800{sup o}C was observed, which was connected to a dramatic increase of the average pore size. Initially amorphous structures were replaced by the crystalline Na-feldspars. In materials prepared using fly ash and potassium silicate compressive strength was significantly increased on heating, deterioration of strength started at 1000{sup o}C. After firing these materials remained amorphous with reduced average pore size and significantly increased compressive strength. Compaction at 1-10 MPa reduced shrinkage on firing in all materials. Geopolymer materials prepared using class F fly ash and alkaline activators showed high shrinkage as well as large changes in compressive strength with increasing fired temperature in the range of 800-1200{sup o}C. Thus the materials were found unsuitable for refractory insulation applications.

  8. Mechanical properties and microstructure analysis of fly ash geopolymeric recycled concrete.

    Science.gov (United States)

    Shi, X S; Collins, F G; Zhao, X L; Wang, Q Y

    2012-10-30

    Six mixtures with different recycled aggregate (RA) replacement ratios of 0%, 50% and 100% were designed to manufacture recycled aggregate concrete (RAC) and alkali-activated fly ash geopolymeric recycled concrete (GRC). The physical and mechanical properties were investigated indicating different performances from each other. Optical microscopy under transmitted light and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX) were carried out in this study in order to identify the mechanism underlying the effects of the geopolymer and RA on concrete properties. The features of aggregates, paste and interfacial transition zone (ITZ) were compared and discussed. Experimental results indicate that using alkali-activated fly ash geopolymer as replacement of ordinary Portland cement (OPC) effectively improved the compressive strength. With increasing of RA contents in both RAC and GRC, the compressive strength decreased gradually. The microstructure analysis shows that, on one hand, the presence of RA weakens the strength of the aggregates and the structure of ITZs; on the other hand, due to the alkali-activated fly ash in geopolymer concrete, the contents of Portlandite (Ca(OH)(2)) and voids were reduced, as well as improved the matrix homogeneity. The microstructure of GRC was changed by different reaction products, such as aluminosilicate gel. PMID:22954605

  9. Strength Properties of Fly Ash Based Geopolymer Concrete with Sea Sand

    Directory of Open Access Journals (Sweden)

    B. H. Shinde

    2016-07-01

    Full Text Available The production of every ton of cement contributes to production of one ton of CO2. With the development of infra activities, the power sector activities are also increasing. The coal based power plant produces huge quantity of fly ash, which creates its disposal problems. However to some extent, the fly ash is used as partial substitution to cement. The alkali activated fly ash concrete (Geopolymer Concrete proposed by Devidovits, shows considerable promise for application in construction industry as an alternative to the portland cement for precast concrete. Day by day the scarcity of river sand is big problem arrising to construction industry. On the other hand the sea sand is availibile in huge quantity, but the presence of salt and chloride affects strength and durability of cement concrete. In present experimental work the sea sand (Treated and untreated is used as an alternative to river sand and studied the properties of cement concrete and geopolymer concrete. The results show that the untreated sea sand affects the compressive strength in geopolymer concrete same as cement concrete but treated sea sand gives similar results as of river sand concrete

  10. Mechanical properties and microstructure analysis of fly ash geopolymeric recycled concrete.

    Science.gov (United States)

    Shi, X S; Collins, F G; Zhao, X L; Wang, Q Y

    2012-10-30

    Six mixtures with different recycled aggregate (RA) replacement ratios of 0%, 50% and 100% were designed to manufacture recycled aggregate concrete (RAC) and alkali-activated fly ash geopolymeric recycled concrete (GRC). The physical and mechanical properties were investigated indicating different performances from each other. Optical microscopy under transmitted light and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX) were carried out in this study in order to identify the mechanism underlying the effects of the geopolymer and RA on concrete properties. The features of aggregates, paste and interfacial transition zone (ITZ) were compared and discussed. Experimental results indicate that using alkali-activated fly ash geopolymer as replacement of ordinary Portland cement (OPC) effectively improved the compressive strength. With increasing of RA contents in both RAC and GRC, the compressive strength decreased gradually. The microstructure analysis shows that, on one hand, the presence of RA weakens the strength of the aggregates and the structure of ITZs; on the other hand, due to the alkali-activated fly ash in geopolymer concrete, the contents of Portlandite (Ca(OH)(2)) and voids were reduced, as well as improved the matrix homogeneity. The microstructure of GRC was changed by different reaction products, such as aluminosilicate gel.

  11. Silica Fume and Fly Ash Admixed Can Help to Improve the PRC Durability Combine Microscopic Analysis

    Directory of Open Access Journals (Sweden)

    Xiao Li-guang

    2016-01-01

    Full Text Available Silica fume/Fly ash RPC can greatly improve durability. When Silica fume to replace the same amount of 8% of the proportion of cement, re-mixed 15min of mechanically activated Fly ash content of 10%, by chloride ion flux detector measuring, complex doped than the reference RPC impermeability improved significantly; In addition, by using static nitrogen adsorption method showed, RPC internal pore structure determination, the hole integral volume was lower than the reference admixed RPC integral pore volume significantly; And combined SEM microscopic experimental methods, mixed of RPC internal structure and the formation mechanism analysis showed that, SF/FA complex fully embodies the synergy doped composites “Synergistic” principle.

  12. Kinetics Analysis on Mixing Calcination Process of Fly Ash and Ammonium Sulfate

    Institute of Scientific and Technical Information of China (English)

    Peng Wang; Laishi Li; Dezhou Wei

    2014-01-01

    abstract The further development of the extraction of alumina that is produced in the calcination process of ammonium sulfate mixed with fly ash was limited because of the lack of systematic theoretical study. In order to aggrandize the research of the calcination process, the kinetics and reaction mechanism of the calcinations were studied. The result suggests that there are two stages in the calcination process, and the alumina extraction rate increases swiftly in the initial stage, but slows down increasing in the later stage. The apparent activation energy of the initial and later stages equals to 13.31 and 35.65 kJ·mol-1, respectively. In the initial stage, ammonium sulfate reacts directly with mullite in the fly ash to form ammonium aluminum sulfate, while in the later stage, alumi-num sulfate is formed by the reaction between ammonium aluminum sulfate and ammonium sulfate.

  13. EXPERIMENTAL EVALUATION OF LOW CALCIUM FLY ASH BASED GEOPOLYMER CONCRETE

    Directory of Open Access Journals (Sweden)

    NIRAGI DAVE

    2012-12-01

    Full Text Available There are many ways to reduce environmental pollution that causes by production of Portland cement and cause by the increasing of waste material. Geopolymer concrete results from the reaction of a source material that is rich in silica and alumina with alkaline liquid. In this experiment low calcium (ASTM Class F fly ash based Geopolymer is used as the binder, in the replacement of portland cement to produce Geopolymer concrete. The alkaline liquid that been used in geopolymerisation is the combination of sodium hydroxide (NaOH and sodium metasilicate (Na2Sio2. Fly ash has been collected from Badarpur NTPC plant, New Delhi. In the present study, three (3 series of geopolymer concrete specimens composing molar of sodium hydroxide (NaOH which is 8M was adopted. There are 9 cube specimens at size 150mm x 150mm x 150mm were prepared. The test specimenswere cured at 60 degree in an oven and at ambient condition. The curing time varied from 24 hour to 168 hours (7 days. The result shows that the strength of geopolymer concrete after 24 hour is not superior and after 7 day the compressive strength of Geopolymer concrete is moderate. Therefore further curing period and temperatureshould be improved.

  14. Waste glass and fly ash derived glass-ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, S.D.; Yun, Y.H. [Chonnam National University, Kwangju (Republic of Korea)

    2006-07-15

    Crystallization behavior of a waste-based glass-ceramic was studied by means of X-ray diffraction analysis, and the surface morphological observations and chemical compositions were evaluated by field emission-scanning electron microscopy and energy dispersive X-ray spectrometry. Applying the mechanical milling method, the glass-ceramic was prepared by using fly ash from a thermal power plant mixed with waste glass cullet. Powder mixtures consisting of waste glass powder (70 wt%) and fly ash (30 wt%) were used to make glass-ceramic. Various heat treatment temperatures (900, 925, 950, 975, 1000 and 1025{sup o}C) were used to obtain a glass-ceramic of the optimum crystal phase, mechanical properties and chemical durability. The X-ray diffraction analysis showed that the crystalline phases in the glass-ceramic were diopside (Ca(Mg, Al)(Si, Al){sub 2}O-6), augite (Ca(Mg, Fe)Si{sub 2}O{sub 6}) and wollastonite (CaSiO{sub 3}). The crystallization of an acicular phase in the matrix was achieved in the heat treatment temperature range of 1000-1025{sup o}C, and the acicular type main crystal phase in the glass-ceramic was wollastonite (CaSiO{sub 3}). The heat treatment temperature range (1000-1025{sup o}C) also showed much better mechanical properties.

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

    Indian Academy of Sciences (India)

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

    2005-04-01

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

  16. Kinetics of fly ash beneficiation by carbon burnout. [Quarterly report], October 1, 1995--January 30, 1996

    Energy Technology Data Exchange (ETDEWEB)

    Dodoo, J.N.; Okoh, J.M.; Yilmaz, E.

    1996-09-01

    The objective is to investigate the kinetics of beneficiation of fly ash by carbon burnout. The three year project that was proposed is a joint venture between Delmarva Power, a power generating company on the eastern shore of Maryland, and the University of Maryland Eastern Shore. The studies have focused on the beneficiation of fly ash by carbon burnout. The increasing use of coal fly ash as pozzolanic material in Portland cement concrete means that there is the highest economic potential in marketability of large volumes of fly ash. For the concrete industry to consider large scale use the fly ash must be of the highest quality. This means that the residual carbon content of the fly ash must have an acceptable loss on ignition (LOI) value, usually between 7--2% residual carbon. The economic gains to be had from low-carbon ash is a fact that is generally accepted by the electricity generating companies. However, since the cost of producing low-carbon in large quantities, based on present technology, far outweighs any financial gains, no electrical power company using coal as its fuel at present considers the effort worthwhile. The concrete industry would use fly ash in cement concrete mix if it can be assured of its LOI value. At present no utility company would give such assurance. Hence with several million tons of fly ash produced by a single power plant per year all that can be done is to dump the fly ash in landfills. The kinetics of fly ash beneficiation have been investigated in the zone II kinetic regime, using a Cahn TG 121 microbalance in the temperature 550--750{degrees}C. The P{sub 02} and total surface area dependence of the reaction kinetics were determined using a vacuum accessory attached to the microbalance and a surface area analyzer (ASAP 2010), respectively.

  17. How safe is fly ash as building construction material in dwellings

    International Nuclear Information System (INIS)

    Fly ash generated from conventional coal based power plants is disposed off in ash ponds in the form of wet- slurries and is being used as stowing material for underground coal mines, for manufacturing bricks, asbestos sheets, Portland Pozzolona ct-Hlent, land filling etc. In the recent past, there has been increasing interest in making fly ash brick houses due to light wt. of the bricks particularly in hilly areas and earth quake prone areas. It was lesser known hitherto until recently that the fly ash is a potential radioactive air pollutant and it modifies radiation exposure. As the fly ash is burnt coal ash and contains concentrated amount of radionuclides, tracking radon concentration in it is thus fundamental for radiation protection, health and hygiene point of view. Measurement of indoor radon and its progeny levels was carried out in dwellings made up of fly ash bricks using LR-115, Type II plastic track detectors. The measurements indicate moderate to high levels of radon concentration in fly ash samples in itself and fly ash brick houses. For comparison the radon concentration in some typical dwellings made up of Baked Mud Bricks, concrete blocks and mud houses was also carried out. (author)

  18. Research on the influence of the fly ash on the concrete carbonation

    Institute of Scientific and Technical Information of China (English)

    Chen Ce; Zhong Jianchi

    2011-01-01

    The influence of fly ash on the fresh properties, mechanical properties and carbonation properties were studied in this paper. The performance of a kind of curing agent which was applied to the hardened concrete surface was evaluated. Incorporating large volume of fly ash will risk the concrete carbonation. The curing agent could prevent the concrete carbonation, and the mechanism was explained.

  19. Fatigue performance and equations of roller compacted concrete with fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Sun, W.; Liu, J.; Qin, H.; Zhang, Y. [Southeast Univ., Nanjing (China); Jin, Z.; Qian, M. [Highway Bureau of Jiangsu Province (China). Communication Dept.

    1998-02-01

    In this paper, the influence of fly ash on the fatigue performance of roller compacted concrete was studied. The fatigue equations of roller compacted concrete without and with fly ash, which can be used for designing pavement, are proposed through the method of the regressive analysis, and compared with that of the same grade common concrete pavement.

  20. Effect of fly ash on the growth and biochemicals of some Seaweed

    Directory of Open Access Journals (Sweden)

    Sornalakshmi V

    2014-01-01

    Full Text Available The effect of industrial waste fly ash was studied on daily growth rate (DGR, chlorophyll, carotenoids, protein, carbohydrate, lipid and phycocolloids (agar and algin content of four economically important seaweeds, Ulva lactuca, Caulerpa scalpelliformis, Padina tetrastromatica and Gracilaria corticata. The seaweeds were cultured in different concentration of fly ash mixed sterilized seawater. In Ulva lactuca, at lower concentrations of fly ash, the carbohydrate content was found to be more than the control. Protein content was slightly more than the control at 0.25% fly ash while that of lipid at 0.5 and 2.5% concentrations. In Caulerpa scalpelliformis, fly ash at all the concentrations induced reduced DGR and lipid content but increased chlorophyll a and chlorophyll b amount. The amount of protein was more than the control at 0.25, 0.50 and 1.0% fly ash. In Padina tetrastomatica, at almost all the concentrations of fly ash, the amount of Chlorophyll a, chlorophyll c and protein exceeded over the control. In the present study, of the four experimental seaweeds, the red seaweed Gracilaria corticata was found to be most tolerant as this exhibited enhanced growth and biochemical content at most of the concentrations of fly ash.

  1. Influence of fly ash fineness on water requirement and shrinkage of blended cement mortars

    Directory of Open Access Journals (Sweden)

    Vanissorn Vimonsatit

    2015-12-01

    Full Text Available In this paper, the influence of fly ash fineness on water requirement and shrinkage of blended cement mortar was studied. The results indicate that the water requirement and shrinkage characteristic of the blended cement mortar are dependent on fly ash fineness and replacement level. The use of coarse fly ash slightly reduces the water requirement but greatly reduced the drying and the autogenous shrinkage of the blended cement mortars and the reduction is more with an increase in the fly ash replacement level. The finer fly ashes further reduce the water requirement, but increase the drying and the autogenous shrinkages as compared with coarser fly ash. The incorporation of superplasticizer drastically reduces the water requirement, but the effect on the drying and autogenous shrinkages of the normal Portland cement mortar is small. However, for the fly ash mortar, the use of superplasticizer results in a decrease in drying shrinkage and in a substantial increase in the autogenous shrinkage particularly for the fine fly ash at a high replacement level.

  2. Compressive strength and microstructure of carbon nanotubes-fly ash cement composites

    International Nuclear Information System (INIS)

    In this work, carbon nanotubes of 0.5 and 1% by weight were added for the first time in a fly ash cement system to produce carbon nanotubes-fly ash composites in the form of pastes and mortars. Compressive strengths of the composites were then investigated. It was found that the use of carbon nanotubes resulted in higher strength of fly ash mortars. The highest strength obtained for 20% fly ash cement mortars was found at 1% carbon nanotubes where the compressive strength at 28 days was 51.8 MPa. This benefit can clearly be seen in fly ash cement with fly ash of 20% where the importance of the addition of carbon nanotubes means that the relative strength to that of Portland cement became almost 100% at 28 days. In addition, scanning electron micrographs also showed that good interaction between carbon nanotubes and the fly ash cement matrix is seen with carbon nanotubes acting as a filler resulting in a denser microstructure and higher strength when compared to the reference fly ash mix without CNTs.

  3. Fly ash characterization and application in Al-based Mg alloys

    International Nuclear Information System (INIS)

    Continuing study in metallurgical field calls for growing reinforcements of which fly ash plays an important role. In this study, Al alloys were reinforced with different solid fly ash particles. The X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray fluorescence (XRF) analyses were used to identify the fly ash particles, and they were also applied to the composite alloys. The X-ray diffraction (XRD) results indicated that the crystalline phase of the fly ash was an effective reinforced phase. Meanwhile, the SEM and optical micrographs of the composite samples indicated that fly ash could be reacted or settled in the matrix of the aluminium. The physical, tribological and microhardness analyses were also used to study the Al-fly ash composites. The best wear resistance corresponding to the lowest loss was obtained in the samples with as-received fly ash which were mostly in accordance with the results in the samples containing treated fly ash. Meanwhile, the proportion of the wear results to the hardness of the samples was observed. Finally, the light weight Al alloys was realized, and increasing the strength is a likeness.

  4. Strength and water permeability of concrete containing various types of fly ashes and filler material

    Energy Technology Data Exchange (ETDEWEB)

    Homwuttiwong, Sahalaph [Mahasarakham Univ. (Thailand). Faculty of Engineering; Chindaprasirt, Prinya [Khon Kaen Univ. (Thailand). Sustainable Infrastructure Research and Development Center and Dept. of Civil Engineering; Jaturapitakkul, Chai [King Mongkut' s Univ. of Technology Thonburi (KMUTT), Bangkok (Thailand). Dept. of Civil Engineering

    2012-08-15

    In this study, the strength and water permeability of concretes containing various types of fly ashes and filler material were investigated. Five types of fly ashes with two levels of fineness and ground-river sand were used to partially replace Portland cement at the dosages of 20 and 40% by weight. Results indicated that pulverized coal combustion fly ash produced concrete with good strength and low permeability. Normal fluidized bed combustion fly ashes containing very irregular particles with pores produced concrete with low strength and relatively low permeability. Fly ash from fluidized bed combustion of coal with biomass materials and fly ash with high amount of CaO and SO{sub 3} produced poor concretes with low strength and high permeability. The increase in fly ash fineness helped improve both strength and permeability of concrete due to the increase in the reactivity of fly ash. Filler material could also be used to replace Portland cement at low replacement level of 20% with small effects on strength and water permeability. (orig.)

  5. The Effects of High Alkaline Fly Ash on Strength Behaviour of a Cohesive Soil

    Directory of Open Access Journals (Sweden)

    A. Binal

    2016-01-01

    Full Text Available Contemporarily, there are 16 coal-burning thermal power plants currently operating in Turkey. This number is expected to rise to 46 in the future. Annually, about 15 million tons of fly ash are removed from the existing thermal power plants in Turkey, but a small proportion of it, 2%, is recyclable. Turkey’s plants are fired by lignite, producing Class C fly ash containing a high percentage of lime. Sulfate and alkali levels are also higher in Class C fly ashes. Therefore, fly ash is, commonly, unsuitable as an additive in cement or concrete in Turkey. In this study, highly alkaline fly ash obtained from the Yeniköy thermal power plants is combined with soil samples in different proportions (5%, 10%, 15%, 20%, and 25% and changes in the geomechanical properties of Ankara clay were investigated. The effect of curing time on the physicomechanical properties of the fly ash mixed soil samples was also analyzed. The soil classification of Ankara clay changed from CH to MH due to fly ash additives. Free swelling index values showed a decrease of 92.6%. Direct shear tests on the cohesion value of Ankara clay have shown increases by multiples of 15.85 and 3.01 in internal friction angle values. The California bearing ratio has seen a more drastic increase in value (68.7 times for 25% fly ash mix.

  6. Permeation Properties and Pore Structure of Surface Layer of Fly Ash Concrete

    Directory of Open Access Journals (Sweden)

    Jun Liu

    2014-05-01

    Full Text Available This paper presents an experimental study on the nature of permeation properties and pore structure of concrete surface layers containing fly ash. Concretes containing different dosages of fly ash as a replacement for cement (15% and 30% by weight of total cement materials, respectively were investigated. Concrete without any fly ash added was also employed as the reference specimen. Laboratory tests were conducted to determine the surface layer properties of concrete including chloride transport, apparent water permeability and pore structure. The results demonstrate that incorporation of fly ash, for the early test period, promotes the chloride ingress at the surface layer of concrete but substituting proportions of fly ash may have little impact on it. With the process of chloride immersion, the chloride concentration at the surface layer of concrete with or without fly ash was found to be nearly the same. In addition, it is suggested that the water permeability at the concrete surface area is closely related to the fly ash contents as well as the chloride exposure time. Pore structure was characterized by means of mercury intrusion porosimetry (MIP test and the scanning electron microscopy (SEM images. The modification of pore structure of concrete submersed in distilled water is determined by the pozzolanic reaction of fly ash and the calcium leaching effect. The pozzolanic reaction was more dominant at the immersion time of 180 days while the calcium leaching effect became more evident after 270 days.

  7. Effect of the Composite of Natural Zeolite and Fly Ash on Alkali-Silica Reaction

    Institute of Scientific and Technical Information of China (English)

    FENG Xiao-xin; FENG Nai-qian; HAN Dong

    2003-01-01

    The effect of the composite of natural zeolite and fly ash on alkali-silica reaction ( ASR ) was studied with natural alkali-reactive aggregate and quartz glass aggregate respecthvely. The expansive experiment of mortar bar and concrete prism was completed. The results show that ASR can be suppressed effectively by the composite of natural zeolite and fly ash.

  8. Post-treatment of Fly Ash by Ozone in a Fixed Bed Reactor

    DEFF Research Database (Denmark)

    Pedersen, Kim Hougaard; Melia, M. C.; Jensen, Anker Degn;

    2009-01-01

    prevents the AEA to be adsorbed. In the present work, two fly ashes have been ozonated in a fixed bed reactor and the results showed that ozonation is a potential post-treatment method that can lower the AEA requirements of a fly ash up to 6 times. The kinetics of the carbon oxidation by ozone was found...

  9. Improved Reactivity of Fly Ash-Slag Geopolymer by the Addition of Silica Fume

    Directory of Open Access Journals (Sweden)

    N. K. Lee

    2016-01-01

    Full Text Available This study investigates the improved reactivity of a geopolymer based on a combination of fly ash and blast furnace slag (BFS by the addition of silica fume. The geopolymer was synthesized by activating a mixture of fly ash, BFS, and three different types of silica fume with alkali activator. X-ray diffraction (XRD and inductively coupled plasma-optical emission spectroscopy (ICP-OES were utilized to characterize the reaction. The silicate structure was also analyzed by nuclear magnetic resonance (NMR spectroscopy. From these results, it was found that the replacement of fly ash with the silica fume led to a significant decrease in the Q4(1Al and an increase in the Q4(2Al, Q4(3Al, and Q4(4Al. The Si/Al ratio of the aluminosilicate gel was relatively constant, ranging from 2.0 to 2.6, while the Si/Al ratio of the C-S-H gel increased with the addition of silica fume. Therefore, some of the Al dissolved from the slag contributed to the formation of aluminosilicate gel, and the remnant slag particles mostly participated in the formation of the C-(A-S-H gel with a decrease in the Q2(1Al. The increase in the reactivity of slag caused by the addition of silica fume was attributed to the reaction of the Al in the slag with the silica fume.

  10. Environmental, physical and structural characterisation of geopolymer matrixes synthesised from coal (co-)combustion fly ashes.

    Science.gov (United States)

    Alvarez-Ayuso, E; Querol, X; Plana, F; Alastuey, A; Moreno, N; Izquierdo, M; Font, O; Moreno, T; Diez, S; Vázquez, E; Barra, M

    2008-06-15

    The synthesis of geopolymer matrixes from coal (co-)combustion fly ashes as the sole source of silica and alumina has been studied in order to assess both their capacity to immobilise the potentially toxic elements contained in these coal (co-)combustion by-products and their suitability to be used as cement replacements. The geopolymerisation process has been performed using (5, 8 and 12 M) NaOH solutions as activation media and different curing time (6-48 h) and temperature (40-80 degrees C) conditions. Synthesised geopolymers have been characterised with regard to their leaching behaviour, following the DIN 38414-S4 [DIN 38414-S4, Determination of leachability by water (S4), group S: sludge and sediments. German standard methods for the examination of water, waste water and sludge. Institut für Normung, Berlin, 1984] and NEN 7375 [NEN 7375, Leaching characteristics of moulded or monolithic building and waste materials. Determination of leaching of inorganic components with the diffusion test. Netherlands Normalisation Institute, Delft, 2004] procedures, and to their structural stability by means of compressive strength measurements. In addition, geopolymer mineralogy, morphology and structure have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), respectively. It was found that synthesised geopolymer matrixes were only effective in the chemical immobilisation of a number of elements of environmental concern contained in fly ashes, reducing (especially for Ba), or maintaining their leachable contents after the geopolymerisation process, but not for those elements present as oxyanions. Physical entrapment does not seem either to contribute in an important way, in general, to the immobilisation of oxyanions. The structural stability of synthesised geopolymers was mainly dependent on the glass content of fly ashes, attaining at the optimal activation conditions (12 M NaOH, 48 h, 80

  11. Development of iron oxide and titania treated fly ash based ceramic and its bioactivity

    International Nuclear Information System (INIS)

    The increasing accumulation of fly ash from thermal power plants poses a major problem to the environment. The present work reflects the novel utilization of this profusely available industrial waste in the form of an antibacterial hard ceramic material by treating fly ash with ferric oxide (Fe2O3) and titania (TiO2) during sintering process at 1600 °C. The developed material shows more than 90% bacterial reduction against both Gram-positive and Gram-negative bacteria. The mechanism of their antibacterial action was studied by transmission electron microscopy (TEM) image analysis of the bacterial cross-section. The developed ceramic material acquires hardness due to the enhancement of the natural mullite content in the matrix. The mullite content and the crystallinity of mullite have shown their increasing trend with increasing concentration of the metal oxide during sintering process. A maximum of ∼ 37% increase in mullite was obtained for 7% w/w Fe2O3 and TiO2. Metal oxide lowered the activation energy of the reaction and enhanced the reaction rate of alumina (Al2O3)–silica (SiO2) to form mullite which increases the hardness. The study highlights novel utilization of fly ash as a hard ceramic antibacterial product (bioceramics) for both structural and hygiene applications in an eco-friendly way. - Highlights: ► A novel antibacterial hard ceramic material by treating fly ash with metal oxide. ► The material shows excellent antibacterial activity (> 90%) against pathogenic bacteria. ► Mechanism of antibacterial action by TEM analysis. ► Enhancement of the concentration of ‘natural mullite content’ in the material. ► Hardness induced by enhanced mullite content is an added advantage for prolonged product life.

  12. Effects of chemical composition of fly ash on efficiency of metal separation in ash-melting of municipal solid waste

    International Nuclear Information System (INIS)

    Highlights: ► Separation of Pb and Zn from Fe and Cu in ash-melting of municipal solid waste. ► Molar ratio of Cl to Na and K in fly ash affected the metal-separation efficiency. ► The low molar ratio and a non-oxidative atmosphere were better for the separation. - Abstract: In the process of metal separation by ash-melting, Fe and Cu in the incineration residue remain in the melting furnace as molten metal, whereas Pb and Zn in the residue are volatilized. This study investigated the effects of the chemical composition of incineration fly ash on the metal-separation efficiency of the ash-melting process. Incineration fly ash with different chemical compositions was melted with bottom ash in a lab-scale reactor, and the efficiency with which Pb and Zn were volatilized preventing the volatilization of Fe and Cu was evaluated. In addition, the behavior of these metals was simulated by thermodynamic equilibrium calculations. Depending on the exhaust gas treatment system used in the incinerator, the relationships among Na, K, and Cl concentrations in the incineration fly ash differed, which affected the efficiency of the metal separation. The amounts of Fe and Cu volatilized decreased by the decrease in the molar ratio of Cl to Na and K in the ash, promoting metal separation. The thermodynamic simulation predicted that the chlorination volatilization of Fe and Cu was prevented by the decrease in the molar ratio, as mentioned before. By melting incineration fly ash with the low molar ratio in a non-oxidative atmosphere, most of the Pb and Zn in the ash were volatilized leaving behind Fe and Cu

  13. Gravel road stabilisation of Ehnsjoevaegen, Hallstavik[Using fly ash]; Skogsbilvaegsrenovering av Ehnsjoevaegen, Hallstavik

    Energy Technology Data Exchange (ETDEWEB)

    Macsik, Josef; Svedberg, Bo [Ecoloop, Stockholm (Sweden)

    2006-03-15

    Fly ash in geotechnical applications has stabilising, isolating, low permeability and hardening effect. Fly ash can be used in road constructions with low bearing capacity, as well as on top cover material on landfills. The aim of the project was to build a road section with fly ash stabilised gravel, based on laboratory studies, and follow up technical and environmental aspect during the first year after stabilisation. The overall aim of this project was to evaluate fly ash from Holmen Paper, Hallstavik, from technical and environmental point of view in a gravel road construction. A gravel road, Ehnsjoevaegen, was stabilised with fly ash during autumn 2004. This road was a low priority road. The fly ash stabilised road section was 1300 m long. Gravel from the road Ehnsjoevaegen was stabilised and investigated in a laboratory study. Leachability of metals and geotechnical aspects were investigated. The laboratory study showed that fly ash stabilised gravel has high shear strength, however its thawing resistance is not fully acceptable. Additives of cement or merit are needed in order to increase its thawing resistance. The actual road section is not going to be used during thawing period and no additives were used. The test road is divided into different sections including a reference section. The road stabilisation work was conducted with gravel transported to Ehnsjoevaegen from off site and not with gravel from the site. Fly ash was tipped off on a levelled road, followed by tipping of gravel. Mixing fly ash and gravel was done on site by a road scraper. After the mixing the road was gravelled with 0,1 m graded gravel. In this project the fly ash had low water content. In order to get optimal compaction water was added from a tanker supplying water before compacted with a compactor. Results from the pilot test shows that fly ash stabilised gravel can be tipped, mixed and compacted effectively. Tipping can be optimised if fly ash and gravel is mixed in a mixer

  14. Properties of Concrete using Tanjung Bin Power Plant Coal Bottom Ash and Fly Ash

    Directory of Open Access Journals (Sweden)

    Abdulhameed Umar Abubakar

    2012-12-01

    Full Text Available Coal combustion by-products (CCPs have been around since man understood that burning coal generates electricity, and its utilization in concrete production for nearly a century. The concept of sustainable development only reawaken our consciousness to the huge amount of CCPs around us and the need for proper reutilization than the current method of disposal which has  severe consequences both to man and the environment. This paper presents the result of utilization of waste from thermal power plants to improve some engineering properties of concrete. Coal bottom ash (CBA and fly ash were utilized in partial replacement for fine aggregates and cement respectively. The results of compressive strength at 7, 28, 56 & 90 days curing are presented because of the pozzolanic reaction. Other properties investigated include physical properties, fresh concrete properties and density. The results showed that for a grade 35 concrete with a combination of CBA and fly ash can produce 28 day strength above 30 MPa.

  15. Treatment and toxicity evaluation of methylene blue using electrochemical oxidation, fly ash adsorption and combined electrochemical oxidation-fly ash adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Kai-sung Wang; Ming-Chi Wei; Tzu-Huan Peng; Heng-Ching Li; Shu-Ju Chao; Tzu-Fang Hsu; Hong-Shen Lee; Shih-Hsien Chang [Chung-Shan Medical University, Taichung (Taiwan)

    2010-08-15

    Treatment of a basic dye, methylene blue, by electrochemical oxidation, fly ash adsorption, and combined electrochemical oxidation-fly ash adsorption was compared. Methylene blue at 100 mg L{sup -1} was used in this study. The toxicity was also monitored by the Vibrio fischeri light inhibition test. When electrochemical oxidation was used, 99% color and 84% COD were removed from the methylene blue solution in 20 min at a current density of 428 A m{sup -2}, NaCl of 1000 mg L{sup -1}, and pH{sub 0} of 7. However, the decolorized solution showed high toxicity (100% light inhibition). For fly ash adsorption, a high dose of fly ash (>20,000 mg L{sup -1}) was needed to remove methylene blue, and the Freundlich isotherm described the adsorption behavior well. In the combined electrochemical oxidation-fly ash adsorption treatment, the addition of 4000 mg L{sup -1} fly ash effectively reduced intermediate toxicity and decreased the COD of the electrochemical oxidation-treated methylene blue solution. The results indicated that the combined process effectively removed color, COD, and intermediate toxicity of the methylene blue solution.

  16. Utilization of fly ash from coal-fired power plants in China

    Institute of Scientific and Technical Information of China (English)

    Da-zuo CAO; Eva SELIC; Jan-Dirk HERBELL

    2008-01-01

    The rapidly increasing demand for energy in China leads to the construction of new power plants all over the country. Coal, as the main fuel resource of those power plants, results in increasing problems with the disposal of solid residues from combustion and off gas cleaning. This investigation describes chances for the utilization of fly ash from coal-fired power plants in China. After briefly comparing the situation in China and Germany, the status of aluminum recycling from fly ash and the advantages for using fly ash in concrete products are introduced. Chemical and physical analyses of Chinese fly ash samples, e.g., X-ray diffraction (XRD), ICP (Inductive Coupled Plasma) and particle size analysis, water requirement, etc. are presented. Reasonable amounts of aluminum were detected in the samples under investigation, but for recovery only sophisticated procedures are available up to now. Therefore, simpler techniques are suggested for the first steps in the utilization of Chinese fly ash.

  17. Assessment of Curing Efficiency and Effect of Moist Curing on Performance of Fly Ash Concrete

    Institute of Scientific and Technical Information of China (English)

    LI Meili; QIAN Jueshi; WANG Lixia; XU Shanshan; JIA Xingwen; FAN Yunyan

    2011-01-01

    This study was conducted to evaluate the sensitivity of compressive strength,water permeability and electrical resistance of near-surface layer concrete with different fly ash contents to curing conditions. It is shown that the sensitivity to curing condition and fly ash content descends in the following order: difference between internal and surface resistivity (ρ)at 28 days, water permeability and compressive strength; both of longer duration of moist curing and use of fly ash in concrete enhanced the water penetration resistance. It is indicated that the resistivity difference p at 28 days can reflect accurately the curing history of fly ash concrete regardless of mix proportions; and use of fly ash in concrete requires longer moist curing duration.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-07-01

    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.

  19. Quantitative Assessment on the Embodied Environmental Impact of Concrete with or without Fly Ash

    Institute of Scientific and Technical Information of China (English)

    LI Sitang; LI Huiqiang

    2005-01-01

    According to the life cycle assessment and the environmental design method of industry production, a quantitative assessment model for the embodied environmental impact of concrete with or without fly ash was proposed. The environmental burden impact indicator (EBII), the resources depletion impact indicator (RDII), and the environmental impact comprehensive indicator (EICI) are defined. The specific environmental impact values of different grade concretes with or without fly ash were presented. In the embodied process of concrete with or without fly ash, the key potential environmental impact categories are global warming and dust emission, and it is an effective way for reducing the embodied environmental impact of concrete to mix fly ash and lower grade cement. The method presented in this paper makes it possible to quantitatively assess the embodied environmental impact of concrete with or without fly ash. The results calculated in this paper can be used to quantitatively assess the life cycle environmental impact of construction materials and buildings.

  20. Synthesis, characterization and conductivity studies of polypyrrole–fly ash composites

    Indian Academy of Sciences (India)

    M V Murugendrappa; Syed Khasim; M V N Ambika Prasad

    2005-10-01

    in situ polymerization of pyrrole was carried out in the presence of fly ash (FA) to synthesize polypyrrole–fly ash composites (PPy/FA) by chemical oxidation method. The PPy/FA composites have been synthesized with various compositions (10, 20, 30, 40 and 50 wt%) of fly ash in pyrrole. The surface morphology of these composites was studied with scanning electron micrograph (SEM). The polypyrrole–fly ash composites were also characterized by employing X-ray diffractometry (XRD) and infrared spectroscopy (IR). The a.c. conductivity behaviour has been investigated in the frequency range 102–106 Hz. The d.c. conductivity was studied in the temperature range from 40–200°C. The dimensions of fly ash in the matrix have a greater influence on the observed conductivity values. The results obtained for these composites are of greater scientific and technological interest.

  1. Composite Ni-Co-fly ash coatings on 5083 aluminium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Panagopoulos, C.N., E-mail: chpanag@metal.ntua.gr [Laboratory of Physical Metallurgy, National Technical University of Athens, Zografos, 15780 Athens (Greece); Georgiou, E.P.; Tsopani, A.; Piperi, L. [Laboratory of Physical Metallurgy, National Technical University of Athens, Zografos, 15780 Athens (Greece)

    2011-03-15

    Ni-Co-fly ash coatings were deposited on zincate treated 5083 wrought aluminium alloy substrates with the aid of the electrodeposition technique. Structural and chemical characterization of the produced composite coatings was performed with the aid of X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron dispersive X-ray analysis (EDS) techniques. The Ni-Co-fly ash coatings were found to consist of a crystalline Ni-Co solid solution with dispersed fly ash particles. In addition, chemical analysis of the Ni-Co matrix showed that it consisted of 80 wt.% Ni and 20 wt.% Co. The co-deposition of fly ash particles leads to a significant increase of the microhardness of the coating. The corrosion behaviour of the Ni-Co-fly ash/zincate coated aluminium alloy, in a 0.3 M NaCl solution (pH = 3.5), was studied by means of potentiodynamic corrosion experiments.

  2. Investigation of the possibility of binding fly ash particles by elemental sulphur

    Directory of Open Access Journals (Sweden)

    Vidojković V.

    2006-01-01

    Full Text Available Thermal power plants in Serbia use lignite for electrical power production The secondary product of coal combustion is fly ash in the amount of 17%. Fly ash causes the pollution of air, water and soil, and also cause many human, especially lung diseases. Secondary sulphur is a product of crude oil refining. The aim of this study was to investigate the use of sulphur as a bonding material in ultra fine particle agglomeration (smaller than 63 μm in fly ash. The agglomeration should make the ash particles larger and heavy enough to fall without flying fractions. The experiments showed that during the homogenization of the ashes and sulphur from 150 to 170 °C in a reactor with intensive mixing, an amount of 15% sulphur was sufficient to bond particles and cause agglomeration without visible flying fractions.

  3. Statistical Analyses of Optimum Partial Replacement of Cement by Fly Ash Based on Complete Consumption of Calcium Hydroxide

    Directory of Open Access Journals (Sweden)

    Ouypornprasert Winai

    2016-01-01

    Full Text Available The objectives of this technical paper were to propose the optimum partial replacement of cement by fly ash based on the complete consumption of calcium hydroxide from hydration reactions of cement and the long-term strength activity index based on equivalent calcium silicate hydrate as well as the propagation of uncertainty due to randomness inherent in main chemical compositions in cement and fly ash. Firstly the hydration- and pozzolanic reactions as well as stoichiometry were reviewed. Then the optimum partial replacement of cement by fly ash was formulated. After that the propagation of uncertainty due to main chemical compositions in cement and fly ash was discussed and the reliability analyses for applying the suitable replacement were reviewed. Finally an applicability of the concepts mentioned above based on statistical data of materials available was demonstrated. The results from analyses were consistent with the testing results by other researchers. The results of this study provided guidelines of suitable utilization of fly ash for partial replacement of cement. It was interesting to note that these concepts could be extended to optimize partial replacement of cement by other types of pozzolan which were described in the other papers of the authors.

  4. Use of Fly Ash as a Potential Coagulant in the Physico-Chemical Treatment of Domestic Wastewater

    OpenAIRE

    SARI, Bülent; BAYAT, Belgin

    2002-01-01

    The effectiveness of fly ash as a coagulant for domestic wastewater treatment was investigated and compared with aluminium sulfate and ferric chloride. In these experiments, four fly ash samples with different chemical compositions obtained from different coal- fired power plants in Turkey were used. In all coagulation-flocculation experiments using fly ash, it was apparent that the predominant removal mechanism varied with the pH and the chemical components of the fly ash. According to our r...

  5. Surface and bulk characterization of an ultrafine South African coal fly ash with reference to polymer applications

    Science.gov (United States)

    van der Merwe, E. M.; Prinsloo, L. C.; Mathebula, C. L.; Swart, H. C.; Coetsee, E.; Doucet, F. J.

    2014-10-01

    South African coal-fired power stations produce about 25 million tons of fly ash per annum, of which only approximately 5% is currently reused. A growing concern about pollution and increasing landfill costs stimulates research into new ways to utilize coal fly ash for economically beneficial applications. Fly ash particles may be used as inorganic filler in polymers, an application which generally requires the modification of their surface properties. In order to design experiments that will result in controlled changes in surface chemistry and morphology, a detailed knowledge of the bulk chemical and mineralogical compositions of untreated fly ash particles, as well as their morphology and surface properties, is needed. In this paper, a combination of complementary bulk and surface techniques was explored to assess the physicochemical properties of a classified, ultrafine coal fly ash sample, and the findings were discussed in the context of polymer application as fillers. The sample was categorized as a Class F fly ash (XRF). Sixty-two percent of the sample was an amorphous glass phase, with mullite and quartz being the main identified crystalline phases (XRD, FTIR). Quantitative carbon and sulfur analysis reported a total bulk carbon and sulfur content of 0.37% and 0.16% respectively. The spatial distribution of the phases was determined by 2D mapping of Raman spectra, while TGA showed a very low weight loss for temperatures ranging between 25 and 1000 °C. Individual fly ash particles were characterized by a monomodal size distribution (PSD) of spherical particles with smooth surfaces (SEM, TEM, AFM), and a mean particle size of 4.6 μm (PSD). The BET active surface area of this sample was 1.52 m2/g and the chemical composition of the fly ash surface (AES, XPS) was significantly different from the bulk composition and varied considerably between spheres. Many properties of the sample (e.g. spherical morphology, small particle size, thermal stability) appeared

  6. Evaluation of Changes in Index Properties of Lateritic Soil Stabilized with Fly Ash

    Directory of Open Access Journals (Sweden)

    Agapitus AMADI

    2010-12-01

    Full Text Available For soils to be suitable in civil engineering projects, they must meet existing local requirements for index properties in addition to certain strength criteria. Typically, specifications limit these properties to some threshold values which in most cases are project specific. Some lateritic soils in their natural state need some treatment/modification to meet these specification requirements. The objective of this study was to evaluate changes in the index properties (i.e., particle size distribution, Atterberg limits and compaction characteristics of a residually derived lateritic soil following fly ash application. Lateritic soil – fly ash mixtures with up to 20% fly ash by dry weight of soil were tested and specimens for compaction characteristics were prepared at different compaction states (optimum, dry and wet of optimum moisture content and compacted using British Standard Light (BSL compactive effort. While soil – fly ash mixtures containing up to 15% fly ash classify as CL according to USCS classification system and plotted above A-line in the plasticity chart, it was observed that changes in the gradation characteristics of soil sample treated with 20% fly ash resulted in the alteration of its classification to ML as well as the crossing of the A- line to the silty region. The liquid limit (LL varied from 42.2 to 29.53% representing 70% reduction while the plasticity index (PI of specimen treated with 20% fly ash was 16% lower than that of natural soil. The optimum moisture content (OMC ranged from 17.36% for the natural soil to 18.34% for soil mixtures containing 20% fly ash which yielded dry unit weight of 17.2kN/m3 for the natural soil and 16.1kN/m3 for samples treated with 20% fly ash. From the study, useful data were obtained showing substantial and desirable changes in the properties of lateritic soil as a civil engineering material on application of fly ash.

  7. Gaseous mercury from curing concretes that contain fly ash: laboratory measurements.

    Science.gov (United States)

    Golightly, Danold W; Sun, Ping; Cheng, Chin-Min; Taerakul, Panuwat; Walker, Harold W; Weavers, Linda K; Golden, Dean M

    2005-08-01

    Total gaseous mercury in headspace air was measured for enclosed concretes dry curing at 40 degrees C for intervals of 2, 28, and 56 days. Release of mercury was confirmed for ordinary Portland cement concrete (OPC) and three concretes in which class F fly ash substituted for a fraction of the cement: (a) 33% fly ash (FA33), (b) 55% fly ash (FA55), and (c) 33% fly ash plus 0.5% mercury-loaded powdered activated carbon (HgPAC). Mean rates of mercury release (0.10-0.43 ng/day per kg of concrete) over the standard first 28 days of curing followed the order OPC mercury flux from exposed surfaces of these concretes ranged from 1.9 +/- 0.5 to 8.1 +/-2.0 ng/m(2)/h, values similar to the average flux for multiple natural substrates in Nevada, 4.2 +/- 1.4 ng/m(2)/h, recently published by others. Air sampling extending for 28 days beyond the initial 28-day maturation for OPC, FA55, and HgPAC suggested that the average Hg release rate by OPC is constant over 56 days and that mercury release rates for FA55 and HgPAC may ultimately diminish to levels exhibited by OPC concrete. The release of mercury from all samples was less than 0.1% of total mercury content over the initial curing period, implying that nearly all of the mercury was retained in the concrete. PMID:16124303

  8. Trends in the Rare Earth Element Content of U.S.-Based Coal Combustion Fly Ashes.

    Science.gov (United States)

    Taggart, Ross K; Hower, James C; Dwyer, Gary S; Hsu-Kim, Heileen

    2016-06-01

    Rare earth elements (REEs) are critical and strategic materials in the defense, energy, electronics, and automotive industries. The reclamation of REEs from coal combustion fly ash has been proposed as a way to supplement REE mining. However, the typical REE contents in coal fly ash, particularly in the United States, have not been comprehensively documented or compared among the major types of coal feedstocks that determine fly ash composition. The objective of this study was to characterize a broad selection of U.S. fly ashes of varied geological origin in order to rank their potential for REE recovery. The total and nitric acid-extractable REE content for more than 100 ash samples were correlated with characteristics such as the major element content and coal basin to elucidate trends in REE enrichment. Average total REE content (defined as the sum of the lanthanides, yttrium, and scandium) for ashes derived from Appalachian sources was 591 mg kg(-1) and significantly greater than in ashes from Illinois and Powder River basin coals (403 and 337 mg kg(-1), respectively). The fraction of critical REEs (Nd, Eu, Tb, Dy, Y, and Er) in the fly ashes was 34-38% of the total and considerably higher than in conventional ores (typically less than 15%). Powder River Basin ashes had the highest extractable REE content, with 70% of the total REE recovered by heated nitric acid digestion. This is likely due to the higher calcium content of Powder River Basin ashes, which enhances their solubility in nitric acid. Sc, Nd, and Dy were the major contributors to the total REE value in fly ash, based on their contents and recent market prices. Overall, this study shows that coal fly ash production could provide a substantial domestic supply of REEs, but the feasibility of recovery depends on the development of extraction technologies that could be tailored to the major mineral content and origins of the feed coal for the ash. PMID:27228215

  9. Thermodynamics and kinetics of alumina extraction from fly ash using an ammonium hydrogen sulfate roasting method

    Institute of Scientific and Technical Information of China (English)

    Ruo-chao Wang; Yu-chun Zhai; Zhi-qiang Ning

    2014-01-01

    A novel method was developed for extracting alumina (Al2O3) from fly ash using an ammonium hydrogen sulfate (NH4HSO4) roasting process, and the thermodynamics and kinetics of this method were investigated. The thermodynamic results were verified experi-mentally. Thermodynamic calculations show that mullite present in the fly ash can react with NH4HSO4 in the 298-723 K range. Process op-timization reveals that the extraction rate can reach up to 90.95% when the fly ash reacts with NH4HSO4 at a 1:8 mole ratio of Al2O3/NH4HSO4 at 673 K for 60 min. Kinetic analysis indicates that the NH4HSO4 roasting process follows the shrinking unreacted core model, and inner diffusion through the product layer is the rate-controlling step. The activation energy is calculated to be 16.627 kJ/mol;and the kinetic equation can be expressed as 1-(2/3)α-(1-α)2/3=0.0374t exp[-16627/(RT)], whereαis the extraction rate and t is the roasting temperature.

  10. Fly ash-based geopolymer as a novel photocatalyst for degradation of dye from wastewater

    Institute of Scientific and Technical Information of China (English)

    Yaojun Zhang; Licai Liu

    2013-01-01

    The geopolymer synthesized by alkali-activated fly ash was firstly used as a novel photocatalyst for degradation of methylene blue (MB) dye from wastewater.The geopolymer is composed of nanoparticulates with an average particle size of about 50 nm.More than 90% of pore volume in the fly ash-based geopolymet predominately centralized on the pore size in the range of 17-700 nm.The degradation efficiency of MB dye by fly ash-based geopolymer catalyst was up to 92.79% under UV irradiation due to the synergistic effect of adsorption and semiconductor photocatalysis.The pseudo-first-order and pseudo-second-order rate equations as well as intra-particle diffusion rate equation were employed to correlate analysis for the adsorption kinetics of MB dye.The experimental data agreed well with pseudo-second-order rate equation in both cases of with UV and without UV irradiations.The intra-particle diffusion process is not the rate determining step.The photocatalytic degradation of MB dye in solution obeys third-order reaction kinetics.

  11. In situ ATR-FTIR study of the early stages of fly ash geopolymer gel formation.

    Science.gov (United States)

    Rees, Catherine A; Provis, John L; Lukey, Grant C; van Deventer, Jannie S J

    2007-08-14

    The kinetics of geopolymer formation are monitored using a novel in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopic technique. Reaction rates are determined from the intensity variation of the bands related to the geopolymer gel network and the unreacted fly ash particles. Comparison with deuterated geopolymer samples provides critical information regarding peak assignments. An initial induction (lag) period is observed to occur for hydroxide-activated geopolymers, followed by gel evolution according to an approximately linear reaction profile. The length of the lag period is reduced by increasing the concentration of NaOH. An increase in the rate of network formation also occurs with increasing NaOH concentration up to a maximum point, beyond which an increased NaOH concentration leads to a reduced rate of network formation. This trend is attributed to the competing effects of increased alkalinity and stronger ion pairing with an increase in NaOH concentration. In situ analysis also shows that the rate of fly ash dissolution is similar for all moderate- to high-alkali geopolymer slurries, which is attributed to the very highly water-deficient nature of these systems and is contrary to predictions from classical glass dissolution chemistry. This provides for the first time detailed kinetic information describing fly ash geopolymer formation kinetics.

  12. Recovery of gold from gold slag by wood shaving fly ash.

    Science.gov (United States)

    Aworn, Amphol; Thiravetyan, Paitip; Nakbanpote, Woranan

    2005-07-15

    Wood shaving fly ash was used as an alternative adsorbent for gold preconcentration from gold slag. The maximum gold adsorption capacity of wood shaving fly ash washed with tap water (WSFW) at 20, 30, 40, and 60 degrees C was 8.68, 7.79, 7.44, and 7.25 mg(Au)/g(adsorbent), respectively, while of activated carbon it was 76.78, 60.95, 56.13, and 51.90 mg(Au)/g(adsorbent), respectively. Deionized water at 100 degrees C could elute gold adsorbed onto WSFW to 71%. The effect of the increasing temperature of water, 30, 60, and 100 degrees C, implied that the adsorption mechanism was mainly physical adsorption. The negative values of enthalpy change (DeltaH) and free energy change (DeltaG) indicated an exothermic and spontaneous process, respectively. The positive values of entropy change (DeltaS) indicated increasing disorder of the system. The advantages of wood shaving fly ash are the purification of gold and the easier recycling of gold from the gold-adsorbed adsorbent. PMID:15925603

  13. Utilisation of Turkish fly ashes in cost effective HVFA concrete production

    Energy Technology Data Exchange (ETDEWEB)

    Burak Felekoglu [Dokuz Eylul University, Izmir (Turkey). Civil Engineering Department

    2006-09-15

    High-volume fly ash (HVFA) concrete is an economical and durable option for structural as well as general concreting purposes, if properly controlled ashes are employed. The aim of this study was to investigate the possibility of the use of three types of Turkish fly ashes from different sources in cost effective high-volume fly ash concrete production. For this purpose HVFA concrete mixtures were prepared by substituting 40, 50, 60 and 70% of cement by fly ash. The mechanical properties and material costs of mixtures were compared with conventional concrete at the same strength grade at 28 days. It should be noted that as an additional benefit, the long-term strength development and durability advantageous of HVFA concrete is not taken into consideration in cost analysis. Results showed that for structural applications a technically suitable and cost effective HVFA concrete can only be produced by using the fly ashes within the limits of specific chemical and physical properties. It may be possible to use other fly ashes with rehabilitation and pre-process, which may reduce the economical feasibility of fly ash usage. Short communication. 15 refs., 5 figs., 6 tabs.

  14. Adsorption of Superplasticizers in Fly Ash Blended Cement Pastes and Its Rheological Effects

    Institute of Scientific and Technical Information of China (English)

    CHEN Wei; SHEN Peiliang; SHUI Zhonghe; FAN Jianfeng

    2012-01-01

    The adsorption of superplasticizers in fly ash blended cement paste and its rheological effects were investigated.It is shown that the absorption of superplasticizer on portland cement particles is very different from that on fly ash particles.The fly ash particles have smooth surfaces and are negatively charged,so its adsorption capacity is weaker than the portland cement particles.The amount of adsorbed SP in the fly ash blended cement paste depends highly on the replacement proportion of portland cement with fly ash,and to a much less extent on the nature of the fly ash.However,the amount of adsorbed superplasticizer does not correspond well the ζ-potential of the solid particles,due the strong adsorbing capacities of the Portland cement particles.When fly ash replaces portland cement in the paste,the rheological behavior is radically changed,which is closely related to the fineness and density of the ash.The packing and agglomeration of the solid particles are the controlling factors on the rheological parameters of the fresh paste,instead of the amount and type of adsorbed superplasticizer.

  15. Characterization of Fly Ash from Coal-Fired Power Plant and Their Properties of Mercury Retention

    Science.gov (United States)

    He, Ping; Jiang, Xiumin; Wu, Jiang; Pan, Weiguo; Ren, Jianxing

    2015-12-01

    Recent research has shown that fly ash may catalyze the oxidation of elemental mercury and facilitate its removal. However, the nature of mercury-fly ash interaction is still unknown, and the mechanism of mercury retention in fly ash needs to be investigated more thoroughly. In this work, a fly ash from a coal-fired power plant is used to characterize the inorganic and organic constituents and then evaluate its mercury retention capacities. The as-received fly ash sample is mechanically sieved to obtain five size fractions. Their characteristics are examined by loss on ignition (LOI), scanning electron microscope (SEM), energy dispersive X-ray detector (EDX), X-ray diffraction (XRD), and Raman spectra. The results show that the unburned carbon (UBC) content and UBC structural ordering decrease with a decreasing particle size for the five ashes. The morphologies of different size fractions of as-received fly ash change from the glass microspheres to irregular shapes as the particle size increases, but there is no correlation between particle size and mineralogical compositions in each size fraction. The adsorption experimental studies show that the mercury-retention capacity of fly ash depends on the particle size, UBC, and the type of inorganic constituents. Mercury retention of the types of sp2 carbon is similar to that of sp3 carbon.

  16. Effect of porosity on damping behavior of aluminum matrix-fly ash composites

    Institute of Scientific and Technical Information of China (English)

    DOU Zuo-yong; WU Gao-hui; JIANG Long-tao; DING Bai-suo; CAO Jin-hua

    2006-01-01

    The hollow sphere fly ash/6061Al composite with about 43% porosity in volume fraction (produced by the addition of hollow sphere fly ash particles) was fabricated by squeeze casting technique. Using the same technique, the fly ash/7075Al composite with all the porosity in hollow sphere fly ash infiltrated by molten aluminum was fabricated for partially studying the ash/6061Al composite reached (20.2-26.9)×10-3 and was about 8 times of the value tested by forced vibration method (in the were consistent by the two testing methods and were in the range of (1.1-7.7)×10-3. The effect of temperature on the damping behavior of the materials was also studied. The related damping mechanisms have also been discussed in light of data from the characterization of microstructure and damping capacity. Due to the inferior mechanical properties of the fly ash particles, the tensile strength of the FA/Al composites was lower than that of the corresponding aluminum alloy matrix and was 70.1 MPa and 180.6 MPa for the 'porous' fly ash/6061Al and ‘dense' fly ash/7075Al composite, respectively.

  17. Electrical properties of fly ash and its decarbonization by electrostatic separation

    Institute of Scientific and Technical Information of China (English)

    Tao Youjun; Ding Qingqing; Deng Mingrui; Tao Dongping; Wang Xu; Zhang Jie

    2015-01-01

    The basic principle of fly ash triboelectrification is analysed. The mineral electrical index and test method are introduced. The electric difference of different mineral composition of fly ash is discussed by analysis of chemical and mineral composition of fly ash in Xinwen power plant. The dielectric constant and charge–mass ratio of carbon and ash of fly ash are tested. Combined with the experimental study on rotary triboelectrostatic separation, the charged characteristic of fly ash particles with different size is gained. The results show that the dielectric constant of fly ash with different grain size decreased with the decrease of particle size, which lead to the poor electrical conductivity. Thus it can be seen that par-ticle size plays a leading role in conductivity. The charge of carbon and ash with each size increased with the decreased of particle size;and the charge–mass ratio between carbon and ash with the same size lar-ger with the decrease of size, which indicated that the finer particle size, the more favorable for triboelec-trification separation. In the same conditions, the best decarburization effect is realized when the particle size ranges from 0.038 to 0.074 mm, whose decarbonization rate and efficiency index reached 38.93%and 120.83%respectively.

  18. Properties of High-Volume Fly Ash Concrete Reinforced with Natural Fibres

    Directory of Open Access Journals (Sweden)

    Rafat SIDDIQUE

    2012-12-01

    Full Text Available Properties of high-volume fly ash concrete incorporating san fibres are presented in this paper. For this investigation, initially, three concrete mixtures were made with 35%, 45%, and 55% of Class F fly as partial replacement of cement. After this, three percentages (0.25, 0.50, and 0.75% of san fibres (25 mm length were added in each of the fly ash concrete mixtures. San is a natural bast fibre, and is also known as Sunn Hemp (Botanical name: Crotalaria Juncea. It is grown in Indian Sub-Continent, Brazil, Eastern and Southern Africa, and also in some parts of U.S.A. Tests were performed for compressive strength, splitting tensile strength, flexural strength, and impact strength at the ages of 28, 91 and 365 days. Tests were also performed for fresh concrete properties. 28 days test results indicated that san fibres reduced the compressive strength of high-volume fly ash concrete by 2 to 13%, increased splitting tensile strength by 6 to 26%, flexural strength by 5 to 14%, and enhanced impact strength tremendously (by 100 to 300% depending upon the fly ash content and fibre percentage. Later age (91 and 365 days results showed continuous increase in strength properties of high-volume fly ash concrete. This was probably be possible due to the pozzolanic action of fly ash, leading to more densification of the concrete matrix, and development of more effective bond between fibres and fly ash concrete matrix.

  19. The influence of nickel slag aggregate concentration to compressive and flexural strength on fly ash-based geopolymer composite

    Science.gov (United States)

    Sujiono, E. H.; Setiawan, A.; Husain, H.; Irhamsyah, A.; Samnur, S.; Subaer, S.

    2016-04-01

    Fly ash-based geopolymer with nickel slag aggregate has been successfully produced. Fly ash and nickel slag were obtained from Bosowa Jeneponto Power Plant and PT. Vale Indonesia, respectively. This research aims to investigate the influence of nickel slag concentration to compressive strength, flexural strength, and microstructure of geopolymer composite. The increment of nickel slag aggregate on fly ash was relative to the weight of samples. Geopolymer composite were synthesized by using alkali activated method, cured at temperature of 70 °C for 1 hour. The resulting composites were left at room temperature for 14 days, before compressive and flexural strength were performed. The results showed that the addition of nickel slag aggregate was found to increase the compressive strength of the material. The optimum compressive strength was 14.81 MPa with the addition of 10% aggregate. The optimum flexural strength was 2.63 MPa with the addition of 15% aggregate.

  20. Effect of Concentration of Sodium Hydroxide and Degree of Heat Curing on Fly Ash-Based Geopolymer Mortar

    OpenAIRE

    Subhash V. Patankar; Ghugal, Yuwaraj M.; Jamkar, Sanjay S.

    2014-01-01

    Geopolymer concrete/mortar is the new development in the field of building constructions in which cement is totally replaced by pozzolanic material like fly ash and activated by alkaline solution. This paper presented the effect of concentration of sodium hydroxide, temperature, and duration of oven heating on compressive strength of fly ash-based geopolymer mortar. Sodium silicate solution containing Na2O of 16.45%, SiO2 of 34.35%, and H2O of 49.20% and sodium hydroxide solution of 2.91, 5.6...

  1. Kinetics of fly ash beneficiation by carbon burnout. Quarterly report, January--March 1996

    Energy Technology Data Exchange (ETDEWEB)

    Dodoo, J.N.; Okoh, J.M.; Yilmaz, E.

    1996-09-01

    The three year project that was proposed is a joint venture between Delmarva Power, a power generating company on the eastern shore of Maryland, and the University of Maryland Eastern Shore. The studies have focused on the benefication of fly ash by carbon burnout. The increasing use of coal fly ash as pozzolanic material in Portland cement concrete means that there is the highest economic potential in marketability of large volumes of fly ash. For the concrete industry to consider large scale use the fly ash must be of the highest quality. This means that the residual carbon content of the fly ash must have an acceptable loss on ignition (LOI) value, usually between 7-2% residual carbon. The economic gains to be had from low-carbon ash is a fact that is generally accepted by the electricity generating companies. However, since the cost of producing low-carbon in large quantities, based on present technology, far outweighs any financial gains, no electrical power company using coal as its fuel at present considers the effort worthwhile. The concrete industry would use fly ash in cement concrete mix if it can be assured of its LOI value. At present no utility company would give such assurance. Hence with several million tons of fly ash produced by a single power plant per year all that can be done is to dump the fly ash in landfills. The kinetics of fly ash benefication have been investigated in the zone II kinetic regime, using a Cahn TG 121 microbalance in the temperature 550-750{degrees}C. The P{sub O{sub 2}} and total surface area dependence of the reaction kinetics were determined using a vacuum accessory attached to the microbalance and a surface area analyzer (ASAP 2010), respectively. 16 refs., 7 figs., 3 tabs.

  2. THE EFFECT OF FLY ASH ON FLEXURAL CAPACITY CONCRETE BEAMS

    Directory of Open Access Journals (Sweden)

    Amir Mohammad Amiri

    2016-06-01

    Full Text Available This paper presents the flexural response of Reinforced Geopolymer Concrete (RGPC beam. A commercial finite element (FE software ABAQUS has been used to perform a structural behavior of RGPC beam. Using parameters such: stress, strain, Young’s modulus, and Poisson’s ratio obtained from experimental results, a beam model has been simulated in ABAQUS. The results from experimental test and ABAQUS simulation were compared. Due to friction forces at the supports and loading rollers; slip occurring, the actual deflection of RGPC beam from experimental test results were slightly different from the results of ABAQUS. And there is good agreement between the crack patterns of fly-ash based geopolymer concrete generated by FE analysis using ABAQUS, and those in experimental data.

  3. Study on Alkali-activated Silica Fume and Fly Ash Based Geopolymer%碱激发硅灰-粉煤灰基矿物聚合物的研究

    Institute of Scientific and Technical Information of China (English)

    王亚超; 张耀君; 徐德龙

    2011-01-01

    本文在碱激发粉煤灰矿物聚合物的基础上,研究了在粉煤灰中掺人适量硅灰形成碱激发硅灰-粉煤灰基矿物聚合物的性能.结果表明,当碱激发剂Na2SiO3·9H7O用量20wt%,硅灰掺量10wt%时,碱激发硅灰-粉煤灰基矿物聚合物在室温养护下抗压强度达到58.83 Mpa,较不掺硅灰的矿物聚合物强度提高了72%.X衍射分析表明,形成的矿物聚合物为无定形矿物相,SEM微观形貌分析表明,掺入硅灰后,矿物聚合物的微观结构更加致密,其强度大幅度提高.%The performances of alkali-activated silica fume and fly ash based geopolymer were studied based on alkali-activated fly ash geopolymer. The results showed that the compressive strength of geopolymer was 58.83 MPa in the curing time of ambient temperature and it increased by 72% comparing to the geopolymer without silica fume when the amount of activator, Na2SiO3 · 9H20, was 20wt% and incorporation of silica fume was 10wt%. The XRD results demonstrated that the geopolymer took the shape of amorphous phase. SEM images showed that the microstructure of geopolymer was further densification and the compressive strength was significantly improved after silica fume was added.

  4. Sulfate resistance of ordinary Portland cement with fly ash

    Directory of Open Access Journals (Sweden)

    Irassar, Edgardo F.

    1989-03-01

    Full Text Available Low calcium fly ash has demonstrated to be an effective pozzolan to improve sulfate resistance of ordinary portland cement (type I. In this paper physico-chemical effects that produce this pozzolan in the mortar exposed to sulfate attack are studied. Dilution and dispersion affects are analyzed using mixes of cement with an inert mineral admixture. Mineralogical changes of mortar are studied using X-ray diffraction and the help of scanning electron microscope. The results show that fly ash delays mortar cracking phenomenon due to less content of unstable compounds in sulfate environment, greater available space to be occupied by expansive compounds and less CH present in the mortars.

    La ceniza volante de bajo contenido de óxido de calcio ha demostrado ser una efectiva puzolana para mejorar la resistencia a los sulfatos del cemento portland normal (CRN. En el presente trabajo se estudian los efectos físico-químicos que produce esta puzolana en el mortero expuesto al ataque de sulfatos. Se analizan los efectos de dilución y dispersión utilizando mezclas de cemento con una adición mineral inactiva. Los cambios mineralógicos del mortero se estudian con difracción de rayos X (DRX y la ayuda del microscopio electrónico. Los resultados indican que la ceniza volante retarda el fenómeno de fisuración del mortero debido a la menor cantidad de compuestos inestables en ambiente con sulfatos, el mayor espacio disponible para albergar a los compuestos expansivos y la disminución del CH presente en la mezcla.

  5. MANUFACTURING OF ALUMINUM/FLY ASH COMPOSITE WITH LIQUID REACTIVE SINTERING TECHNOLOGY

    Institute of Scientific and Technical Information of China (English)

    X.F. Zhang; D.J. Wang; G. Xie

    2002-01-01

    The Al/fly ash composites are fabricated by liquid reactive sintering P/M process withfly ash particles as intensifying phases. The reactivity and newly formed phases dur-ing liquid sintering process have been analyzed by combing Thermochemical data basecalculation and XRD characterization. The results show that some of constituents infly ash have reacted with liquid aluminum so that the elemental Si, Fe, Ti as well assome amount of intermetallic compounds occur. The properties of aluminum/fly ashcomposites have been improved. With the fraction of fly ash increase, the compositedensity decreases; the hardness and the modulus of the composite increases, and thecomposite wear resistance are significantly increased. The fly ash reinforced compos-ires represent a sort of low cost product with possible widespread applications in theautomotive, small engine, and electromechanical machinery sectors.

  6. Pozzolanic reactivity of silico-aluminous fly ash

    Institute of Scientific and Technical Information of China (English)

    Pierre Adamiec; Jean-Charles Benezet; Ali Benhassaine

    2008-01-01

    For some years it has been possible to control the particle size of fly ashes, by-products of thermal power stations. Incorporating these very fine particles (obtained by grinding and/or pneumatic selection) improves the physical-mechanical characteristics of mortars and concretes. In this study, we measured the lime consumption of the various fractions (granulometric and densimetric) and identified by X-ray diffraction the neoformed phases by the pozzolanic reaction, to show that it is not sufficient to simply define the pozzolanicity of products based on lime consumption since it does not take into account the nature of the phases formed. The size of the particles used in the test samples also has a determining effect on the quantity of lime consumed. Before comparing results, it is necessary to ensure that the size of the particles (of the global ash and its constituents) be the same. Two distinct neoformed phases appear: CSH in the largest granular fractions (d>40 μm) and C<3AH6 in the smaller fractions.

  7. Study of radon exhalation and emanation rates from fly ash samples

    International Nuclear Information System (INIS)

    Fly ash, a by-product of burnt coal is technologically important material being used for manufacturing of bricks, sheets, cement, land filling etc. The increased interest in measuring radon exhalation and emanation rates in fly ash samples is due to its health hazards and environmental pollution and the same have been measured to assess the radiological impact of radon emanated from fly ash disposal sites. Samples of fly ash from different thermal power stations in northern India and National Council for Cement and Building Materials (NCB) were collected and analysed for the measurements. For the measurement, alpha sensitive LR-115 type II plastic track detectors were used. Gamma spectrometry and can technique was used for the measurements. The experimental data show that fly ash samples emanate radon in significant amount and this consequently, may result in increased radon levels in dwellings built by using fly ash bricks and excessive radiation exposure to workers residing in the surroundings of fly ash dumping sites. (author)

  8. Influence of ultra-fine fly ash on hydration shrinkage of cement paste

    Institute of Scientific and Technical Information of China (English)

    GAO Ying-li; ZHOU Shi-qiong

    2005-01-01

    Hydration shrinkage generated by cement hydration is the cause of autogenous shrinkage of high strength concrete. It may result in the volume change and even cracking of mortar and concrete. According to the data analysis in a series of experimental studies, the influence of ultra-fine fly ash on the hydration shrinkage of composite cementitious materials was investigated. It is found that ultra-fine fly ash can reduce the hydration shrinkage of cement paste effectively, and the more the ultra-fine fly ash, the less the hydration shrinkage. Compared with cement paste without the ultra-fine fly ash, the shrinkage ratio of cement paste reduces from 23.4% to 39.7% when the ultra-fine fly ash replaces cement from 20% to 50%. Moreover, the microscopic mechanism of the ultra-fine fly ash restraining the hydration shrinkage was also studied by scanning electron microscopy, X-ray diffraction and hydrated equations. The results show that the hydration shrinkage can be restrained to a certain degree because the ultra-fine fly ash does not participate in the hydration at the early stage and the secondary hydration products are different at the later stage.

  9. Studies on Carbon-Fly Ash Composites with Chopped PANOX Fibers

    Directory of Open Access Journals (Sweden)

    Rakesh V. Patel

    2013-01-01

    Full Text Available Chemical analysis and morphological studies of fly ash reveals the complex chemical constituents present as spherical particles with diameter of less than 25 μm. The constituents of fly ash are silica, alumina, iron oxide, titanium dioxide, calcium and magnesium oxide, and other trace elements. The use of thermosetting as well thermoplastic polymer matrix has been made by several workers to develop polymer matrix fly ash particulate composites by using the hard and abrasive properties of fly ash and lightweight of polymers. Such composites have poor mechanical strength, fracture toughness, and thermal stability. To overcome these shortcomings, in carbonaceous matrix, the carbon fibers were added as additional reinforcement along with the fly ash. The composites were developed with two different methods known as Dry method and Wet method. The processing parameters such as temperature and pressure were optimized in establishing the carbon matrix. Physical, thermal, and mechanical characteristics were studied. The microstructures of composites show good compatibility between fly ash and fibers with the carbon matrix. These composites have higher strength, thermal stability, and toughness as compared to polymer matrix fly ash particulate composites.

  10. Recycling of municipal solid waste incinerator fly ash by using hydrocyclone separation.

    Science.gov (United States)

    Ko, Ming-Sheng; Chen, Ying-Liang; Wei, Pei-Shou

    2013-03-01

    The municipal solid waste incinerators (MSWIs) in Taiwan generate about 300,000 tons of fly ash annually, which is mainly composed of calcium and silicon compounds, and has the potential for recycling. However, some heavy metals are present in the MSWI fly ash, and before recycling, they need to be removed or reduced to make the fly ash non-hazardous. Accordingly, the purpose of this study was to use a hydrocyclone for the separation of the components of the MSWI fly ash in order to obtain the recyclable portion. The results show that chloride salts can be removed from the fly ash during the hydrocyclone separation process. The presence of a dense medium (quartz sand in this study) is not only helpful for the removal of the salts, but also for the separation of the fly ash particles. After the dense-medium hydrocyclone separation process, heavy metals including Pb and Zn were concentrated in the fine particles so that the rest of the fly ash contained less heavy metal and became both non-hazardous and recyclable.

  11. Comparison of various bioassays for dioxins measurements in fuel gas, fly ash and bottom ash

    Energy Technology Data Exchange (ETDEWEB)

    Ota, S.; Kin-ichi, S. [Ministry of the Environment, Tokyo (Japan); Masatoshi, M.; Shin-ichi, S. [National Institute for Environmental Studies, Tsukuba (Japan)

    2004-09-15

    In Japan, the control standards for dioxins (PCDDs, PCDFs and Co-PCBs) in the emission gas, fly and bottom ashes from waste incinerators have been defined in the Law Concerning Special Measures against Dioxins (Dioxins Law). Based on the Dioxins law, an installation personnel of waste incinerators of specified facilities shall measure dioxins in the emission gas and fly and bottom ashes more than once every year followed by reporting the results to their prefectural governor. The present regulating procedure has been set to use high-resolution gas chromatography/ high-resolution mass spectrometry (HRGC/HRMS, hereafter GC/MS) systems to determine dioxin-concentrations. However, the GC/MS measurements are often money- and timeconsuming, since they need complicated steps for sample preparation, expensive equipments and highly skilled technicians. Therefore, it is of high priority to develop rapid and economical alternative methods to measure dioxins. Recently, various assays using biological reactions have drawn a high degree of attention as a candidate for alternative measurement methods of dioxins. During the past decade several studies demonstrated the utility of a chemical (GC/MS) and biological (bioassays/biomarkers) control of waste thermal recycling processes like pyrolysis or incineration treatment. In this paper, we report the results of our recent examinations on the possibility to apply various bioassays to supplementary methods for the present procedure.

  12. Microstructure Development and Transport Properties of Portland Cement-fly Ash Binary Systems: in view of service life predictions

    OpenAIRE

    Z. Yu

    2015-01-01

    Fly ash is a by-product of burning coal in electric power generating plants. It is commonly known that owing to its pozzolanic properties fly ash is widely used as a partial replacement for Portland cement in concrete. The use of fly ash in concrete not only reduces the landfill costs of fly ash, but also reduces the use of Portland cement in concrete, consequently reduces CO2 emission per ton concrete. More important, the presence of fly ash improves the durability of concrete and extends th...

  13. Effects of soil application of fly ash on the fusarial wilt on tomato cultivars

    Energy Technology Data Exchange (ETDEWEB)

    Khan, M.R.; Singh, W.N. [Aligarh Muslim University, Aligarh (India). Dept. of Plant Protection, Rafi Ahmad Kidwai Institute of Agricultural Science

    2001-07-01

    A study was carried out in microplots to evaluate the effect of fly ash on the plant growth and yield of tomato cultivars, Pusa Ruby, Pusa Early Dwarf and New Uday, and on wilt disease caused by Fusarium oxysporum f. sp. lycopersici. Fly ash was applied to soil by broadcast or in rows at the rate of 1, 2, 3 and 4 kg ash m{sup -2} in place of inorganic fertilizers. In control plots, NPK (about 40 : 20 : 20 kg acre{sup -1}) and compost were added in place of fly ash. Ash application greatly increased the soil contents of P, K, B, Ca, Mg, Mn, Zn, carbonates, bicarbonates and sulphates. Plants grown in the ash-treated plots, especially at 3 or 4 kg dose, showed luxuriant growth and greener foliage, and plant growth and yield of the three cultivars were significantly increased in comparison with the plants grown in plots without fly ash. The wilt fungus, F. oxysporum f. sp. lycopersiciat the inoculum level of 2 g plant{sup -1} caused significant suppression of growth and yield in all three cultivars. Application of fly ash, however, checked the suppressive effect of the fungus, leading to a significant increase in the considered variables compared with the inoculated control. Soil population of the fungus gradually decreased with an increase in ash dose. Row application was found to be relatively more effective in enhancing the yield of tomato cultivars and suppressing the wilt disease.

  14. Microstructure and some mechanical properties of fly ash particulate reinforced AA6061 aluminum alloy composites prepared by compocasting

    International Nuclear Information System (INIS)

    Highlights: ► Fabrication of AA6061/fly ash AMC by compocasting method. ► Incorporation of fly ash particles into the semi solid aluminum melt. ► No interfacial reaction between the aluminum matrix and fly ash particle. ► Uniform distribution of fly ash particles having clear interface and good bonding. ► Fly ash particles enhanced the mechanical properties of the AMC. - Abstract: Fly ash has gathered widespread attention as a potential reinforcement for aluminum matrix composites (AMCs) to enhance the properties and reduce the cost of production. Aluminum alloy AA6061 reinforced with various amounts (0, 4, 8 and 12 wt.%) of fly ash particles were prepared by compocasting method. Fly ash particles were incorporated into the semi solid aluminum melt. X-ray diffraction patterns of the prepared AMCs revealed the presence of fly ash particles without the formation of any other intermetallic compounds. The microstructures of the AMCs were analyzed using scanning electron microscopy. The AMCs were characterized with the homogeneous dispersion of fly ash particles having clear interface and good bonding to the aluminum matrix. The incorporation of fly ash particles improved the microhardness and ultimate tensile strength (UTS) of the AMCs

  15. MANUAL. Fly ash in civil engineering, Gravel roads; HANDBOK. Flygaska i mark- och vaegbyggnad, Grusvaegar

    Energy Technology Data Exchange (ETDEWEB)

    Munde, Hanna; Svedberg, Bo; Macsik, Josef; Maijala, Aino; Lahtinen, Pentti; Ekdahl, Peter; Neren, Jens [Vattenfall AB, Stockholm (Sweden). Vaerme Norden

    2006-01-15

    Fly ash based on biofuels or coal has been used as construction material for a long time in roads and other civil engineering applications. Some example, where it has been used in roadbase and subbase of gravel roads, are in the counties of Uppsala, Soedermanland, Vaestmanland and in Finland. The use of fly ash has contributed to good function for example as bearing capacity, thaw and frost capacity and good durability. This has also reduced costs for maintenance. The objective of this project was to develop a manual to provide a base for contemporary use of fly ash in road constructions. In the manual experience from studies, field tests and regulations has been compiled. The manual handles fly ash as base for products to be used in base and subbase in gravel roads. Future user of the guidelines are mainly consultant engineers and contractors. However the aim of the manual is to also support road administrators, environmental authorities and industry. The project has been carried out parallel to another ongoing national project titled 'Guidelines, Use of alternative materials in civil engineering'. The objective of that project is to establish a base for handling of alternative materials in Sweden. Fly ash in gravel roads are mainly used in two typical applications, one without any additive in a single layer and one with fly ash mixed with gravel. The use of flyash provides functional properties such as increased stiffness, stability and enhanced frost and thaw capacity for the road construction in total. Furthermore the products based on fly ash will have low permeability and good frost and thaw durability. These properties are for example related to fly ash quality, design and construction and are in general expected to be better than for traditional constructions using, for example, sand or gravel. The properties can be enhanced further by using binders such as cement and Merit. Fly ash should always be used above the ground water table with

  16. Geotechnical and Physico-Chemical Characterization of Low Lime Fly Ashes

    Directory of Open Access Journals (Sweden)

    Arif Ali Baig Moghal

    2013-01-01

    Full Text Available In order to explore the possibility of using low-lime fly ashes, the physical and chemical properties which have a direct bearing on their geotechnical and geoenvironmental behaviors have been investigated. In this paper, two types of low-lime fly ashes, originating from India, have been used. A brief account of various methods adopted in characterizing their physical, chemical, and geotechnical properties is presented. The relative importance of each of these properties in enhancing the bulk applicability of fly ashes has been brought out.

  17. Influence of Fly Ash on Surface Chloride Concentration Under Shallow Immersion Condition

    OpenAIRE

    Liu, Jun; Wang, Xiaodong; Xing, Feng; Han, Ningxu

    2014-01-01

    In this paper, the influence of fly ash content on concrete surface chloride concentration was investigated through periodical tests of surface chloride concentration of concrete by immersing three kinds of concrete specimens in 5.0 wt.% sodium chloride solution. One kind of specimen is common concrete without fly ash, whereas the other two kinds of specimens are mixed with fly ash. The results show that the surface chloride ion concentration ranges from 0.295 to 0.777 wt.% for the immersed c...

  18. Investigation of the possibility of binding fly ash particles by elemental sulphur

    OpenAIRE

    Vidojković V.; Đorđević N.; Boljanac T.; Vlahović M.; Martinović S.

    2006-01-01

    Thermal power plants in Serbia use lignite for electrical power production The secondary product of coal combustion is fly ash in the amount of 17%. Fly ash causes the pollution of air, water and soil, and also cause many human, especially lung diseases. Secondary sulphur is a product of crude oil refining. The aim of this study was to investigate the use of sulphur as a bonding material in ultra fine particle agglomeration (smaller than 63 μm) in fly ash. The agglomeration should make the as...

  19. Synthesis of zeolites using fly ash and their application in removing heavy metals from waters

    Institute of Scientific and Technical Information of China (English)

    WANG; Yanxin(王焰新); GUO; Yonglong(郭永龙); YANG; Zhihua(杨志华); CAI; Hesheng(蔡鹤生); Xavier; Querol

    2003-01-01

    Three types of zeolite (NaP1 zeolite, analcime and chabazite) were hydrothermally synthesized by reacting fly ash with NaOH solution. The maximum conversion rate from fly ash to single zeolite is about 40%-75%, and the total conversion rate 60%-80%. The synthesis experimental results indicate that factors including vortex, viscosity, temperature, reaction time, and NaOH concentration in the reaction system strongly affect the type and conversion rate of zeolites. The batch experiments of removing Cu2+, Pb2+ and Cd2+ from wastewaters show that the adsorption capacity of zeolites synthesized is higher than that of fly ash.

  20. Effects of fly-ash treatment of soil on yields and chemical composition of chicory

    Energy Technology Data Exchange (ETDEWEB)

    Scotti, I.A.; Lombi, E.; Carini, F.; Silva, S. [Universita Cattolica Sacro Cuore, Piacenza (Italy). Ist. di Chimica Agraria e Ambientale

    1996-09-01

    In pot trials, chicory (Cichorium intybus) was grown on two soils with and without two levels (3% and 10%) of fly ash. It was observed that the addition of 3% fly ash gives rise to a significant increase in the yield and in Mg content, compared to a traditional dressing; all the other elements taken into account (Ca, S, Zn, Mn, Co, Pb, Ni, Cu and B) show positive or negative changes which, in most cases are not significant. With the addition of 10% fly ash the yield decreased, while the concentrations of all the elements, except Mn whose concentration in an acid soil undergoes a reduction, in general show significant increases.

  1. CBR Behaviour of Waste Plastic Strip-Reinforced Stone Dust/Fly Ash Overlying Saturated Clay

    OpenAIRE

    Dutta, R. K.

    2007-01-01

    An experimental study was carried out to investigate the CBR behaviour of waste plastic strip reinforced-stone dust/fly ash overlying saturated clay. Three different sizes of waste plastic strips were used in this study. The effect of waste plastic strip content (0.25% to 4%) and length on the CBR and secant modulus of strip reinforced-stone dust/fly ash overlying saturated clay was investigated. The study reveals that addition of waste plastic strip in stone dust/fly ash overlying ...

  2. Adsorption of anionic dyes from aqueous solutions onto coal fly ash and zeolite synthesized from coal fly ash

    International Nuclear Information System (INIS)

    Coal fly ash, a waste generated in coal-fired electric power plant, was used to synthesize zeolite by hydrothermal treatment with NaOH solution. The fly ash (CL-2) and this synthesized zeolite (ZM-2) that was characterized as hydroxy-sodalite were used as adsorbents for anionic dyes indigo carmine (IC), and reactive orange 16 (RO16) from aqueous solutions. Effects of contact time, initial dye concentration, pH, adsorbent mass, and temperature were evaluated in the adsorption processes. The kinetics studies indicated that the adsorption followed the pseudo-second order kinetics and that surface adsorption and intraparticle diffusion were involved in the adsorption mechanism. The thermodynamics parameters demonstrated that the adsorption was spontaneous for all adsorption processes. The enthalpy data confirmed the endothermic nature for all adsorption processes except for IC/ZM-2 system which was exothermic. The entropy data showed an increased disorder at the solid/solution interface during the adsorption for all systems except for IC/ZM-2 whose negative entropy value indicated a decreased disorder at the interface. The adsorption isotherms were closely fitted to the Langmuir linear equation. The maximum adsorption capacities were 1.48 mg/g for the IC/CL-2 system; 1.13 mg/g for IC/ZM-2; 0.96 mg/g for RO16/CL-2, and 1.14 mg/g for RO16/ZM-2 at room temperature. The desorption study carried out with water, with acid aqueous solutions, and with an alkali aqueous solution showed to be inefficient both for recovering the dyes and regenerating the adsorbents. (author)

  3. The application of electrocoagulation for the conversion of MSWI fly ash into nonhazardous materials.

    Science.gov (United States)

    Liao, Wing-Ping; Yang, Renbo; Kuo, Wei-Ting; Huang, Jui-Yuan

    2014-05-01

    This research investigated the electrocoagulation of municipal solid waste incineration (MSWI) fly ash at a liquid-to-solid ratio (L/S) of 20:1. The leachate that was obtained from this treatment was recovered for reutilization. Two different anodic electrodes were investigated, and two unit runs were conducted. In Unit I, the optimum anode was chosen, and in Unit II, the optimum anode and the recovered leachate were used to replace deionized water for repeating the same electrocoagulation experiments. The results indicate that the aluminum (Al) anode performed better than the iridium oxide (IrO2) anode. The electrocoagulation technique includes washing with water, changing the composition of the fly ash, and stabilizing the heavy metals in the ash. Washing with water can remove the soluble salts from fly ash, and the fly ash can be converted into Friedel's salt (3CaO·Al2O3·CaCl2·10H2O) under an uniform electric field and the sacrificial release of Al(+3) ions, which stabilizes the toxic heavy metals and brings the composition of the fly ash to within the regulatory limits of the toxicity characteristic leaching procedure (TCLP). Use of the Al anode to manage the MSWI fly ash and the leachate obtained from the electrocoagulation treatment is therefore feasible.

  4. Physicochemical properties and heavy metals leachability of fly ash from coal-fired power plant

    Institute of Scientific and Technical Information of China (English)

    Xiang Wei; Han Baoping; Zhou Dong; Nzihou Ange

    2012-01-01

    The physicochemical properties of fly ash from two kinds of coal-fired power plants were studied.Three aspects were examined:the micro-morphology,the mineral composition and the content of heavy met als.The results show that the fly ash from plants using a circulating fluidized bed are more irregular particles,while the particles from the plants using a pulverized coal-fired boiler are mainly spherical in shape.Quartz and mullite are the main crystalline phases in the ash.Clearly,both the technology and the coal used by a power plant can influence the mineral composition of the ash.The mineral composition of fly ash from a circulating fluidized bed is more complex than that from a pulverized coal-fired boiler.The quantity of elements found in the fly ash is greater than that found in the bottom ash for the same plant.Heavy metals are likely to be enriched in the fly ash.Heavy metal leachability was studied using two leaching methods.The results indicate that most of the heavy metals that leached during either batch leaching or column leaching experiments did not exceed the related maximum concentration standards.But Ni concentrations in the leachates from both batch and column tests exceed the standard.The highest excess rates in both tests were 572% and 497%,which levels might threaten the environment.

  5. The Character of Dual Site Adsorbent on Coal Fly Ash Toward Benzene Adsorption

    Directory of Open Access Journals (Sweden)

    Widi Astuti

    2014-10-01

    Full Text Available Large quantities of coal fly ash (CFA are produced during combustion of coal in the production of electricity. Most of this ash has not been widely used. CFA is mainly composed of some oxides including Al2O3 and SiO2 having active site and unburnedcarbon as a mesopore that enables it to act as a dual site adsorbent. To get different characters of dual site, CFA was sieved using 150 mesh size, heated at 400oC and reactedwith sodium hydroxide solution. Furthermore, CFA was used as adsorbent of benzene in aqueous solutions. Equilibrium data were evaluated by single site and dual site isotherm models. It can be concluded that single site model yielded excellent fit with equilibrium data of benzene. The values of maximum concentration of adsorbate in solid surface (Cμm and Langmuir constant (KL are affected by [Si+Al]/C ratio in CFA. The increase of [Si+Al]/C ratio causes a decrease of qm and KL values.Keywords : coal fly ash, adsorption, benzene

  6. Preparation of heteropolyacid/TiO{sub 2}/fly-ash-cenosphere photocatalyst for the degradation of ciprofloxacin from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Wu Di; Huo Pengwei; Lu Ziyang; Gao Xun [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Liu Xiaolin [School of Biology and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212013 (China); Shi Weidong [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Yan Yongsheng, E-mail: huopw@ujs.edu.cn [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2012-07-01

    The TiO{sub 2}/fly-ash cenosphere photocatalysts modified with heteropolyacid were synthesized by sol-gel followed solvothermal method at 40 Degree-Sign C. Their chemical composition and optical absorption were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectra (UV-vis DRS), Fourier Transform Infra Red spectroscopy (FTIR) and Scanning electron microscopy (SEM). It was found that heteropolyacid modification could facilitate the absorption edge of TiO{sub 2}/fly-ash cenosphere photocatalyst to shift the visible light region. Heteropolyoxanion could be loaded on the titanium dioxide surface, by which could hinder the recombination rate of excited electron holes. The photocatalytic activity of TiO{sub 2}/fly-ash cenospheres modified with heteropolyacid was observed for the degradation of ciprofloxacin (CPFX) under visible light irradiation. The result from degradation of CPFX suggested that the photocatalytic activity of TiO{sub 2}/fly-ash cenospheres modified with silicotungstic acid was superior. The synergistic effects of heteropolyacid in modified TiO{sub 2}/fly-ash cenospheres photocatalyst particles were responsible for improving visible light photocatalytic activity. Besides, the novel photocatalyst was easy to recycle during post treatment because the fly-ash cenosphere was adopted for carrier.

  7. Effect of Concentration of Sodium Hydroxide and Degree of Heat Curing on Fly Ash-Based Geopolymer Mortar

    Directory of Open Access Journals (Sweden)

    Subhash V. Patankar

    2014-01-01

    Full Text Available Geopolymer concrete/mortar is the new development in the field of building constructions in which cement is totally replaced by pozzolanic material like fly ash and activated by alkaline solution. This paper presented the effect of concentration of sodium hydroxide, temperature, and duration of oven heating on compressive strength of fly ash-based geopolymer mortar. Sodium silicate solution containing Na2O of 16.45%, SiO2 of 34.35%, and H2O of 49.20% and sodium hydroxide solution of 2.91, 5.60, 8.10, 11.01, 13.11, and 15.08. Moles concentrations were used as alkaline activators. Geopolymer mortar mixes were prepared by considering solution-to-fly ash ratio of 0.35, 0.40, and 0.45. The temperature of oven curing was maintained at 40, 60, 90, and 120°C each for a heating period of 24 hours and tested for compressive strength at the age of 3 days as test period after specified degree of heating. Test results show that the workability and compressive strength both increase with increase in concentration of sodium hydroxide solution for all solution-to-fly ash ratios. Degree of heating also plays vital role in accelerating the strength; however there is no large change in compressive strength beyond test period of three days after specified period of oven heating.

  8. Measurement of natural radioactivity level of fly ash from certain thermoelectricity plant

    International Nuclear Information System (INIS)

    In order to have a comprehensive understanding of radioactivity level of fly ash and its application in a thermoelectricity group in Xi'an, five samples were collected from fly ash stack of the group. Natural radionuclide contents in samples were measured by a low background anti-Compton HPGe Gamma spectrometer. The contents of 238U, 226Ra, 232Th, 40K were 67.6 Bq/kg, 79.5 Bq/kg, 72.7 Bq/kg, 190 Bq/kg, respectively. According to national standard GB 6566-2001, the result indicates the radioactivity level of all samples is at the normal background level and the fly ash can be used as Category A building materials. The future application of the fly ash in the thermoelectricity group was also analyzed. (authors)

  9. Stabilisation of clayey soils with high calcium fly ash and cement

    Energy Technology Data Exchange (ETDEWEB)

    S. Kolias; V. Kasselouri-Rigopoulou; A. Karahalios [National Technical University of Athens, Athens (Greece)

    2005-02-01

    The effectiveness of using high calcium fly ash and cement in stabilising fine-grained clayey soils (CL,CH) was investigated in the laboratory. Strength tests in uniaxial compression, in indirect (splitting) tension and flexure were carried out on samples to which various percentages of fly ash and cement had been added. Modulus of elasticity was determined at 90 days with different types of load application and 90-day soaked CBR values are also reported. Pavement structures incorporating subgrades improved by in situ stabilisation with fly ash and cement were analyzed for construction traffic and for operating traffic. These pavements are compared with conventional flexible pavements without improved subgrades and the results clearly show the technical benefits of stabilising clayey soils with fly ash and cement. In addition TG-SDTA and XRD tests were carried out on certain samples in order to study the hydraulic compounds, which were formed.

  10. Factors affecting the suitability of fly ash as source material for geopolymers

    Energy Technology Data Exchange (ETDEWEB)

    E.I. Diaz; E.N. Allouche; S. Eklund [Louisiana Tech University, Ruston, LA (United States). Department of Civil Engineering

    2010-05-15

    The suitability of fly ash stock piles for geopolymer manufacturing was studied. The results of chemical analyses, X-ray diffraction (XRD) and particle size distribution (PSD) of five sources of fly ash obtained from coal-fired power generating plants in the US are presented. Geopolymer paste and concrete specimens were prepared from each stock pile. The specimens were subjected to an array of chemical and mechanical tests including XRD, RAMAN spectroscopy, setting time and compressive strength. A correlation study was undertaken comparing the fly ash precursor chemical and crystallographic compositions as well as particle size distribution, with the mechanical and chemical characteristics of the resulting geopolymer. Factors inherent to the fly ash stockpile such as particle size distribution, degree of vitrification and location of the glass diffraction maximum were found to play an important role in the fresh and hardened properties of the resulting geopolymer. 26 refs., 7 figs., 2 tabs.

  11. A review of the interference of carbon containing fly ash with air entrainment in concrete

    DEFF Research Database (Denmark)

    Pedersen, Kim Hougaard; Jensen, Anker Degn; Skjøth-Rasmussen, Martin Skov;

    2008-01-01

    adsorption capacity per mass of carbon. Cases reporting increased residual carbon content due to low-NO, combustion are described, together with observations from a pilot scale experiment, where increased AEA adsorption capacity of carbon appeared to relate with firing at low-NO, conditions. Post-treatment...... on the adsorption capacity of AEAs. The type of fuel used in the combustion process influences the amount and properties of the residual carbon. Fly ash derived from bituminous coal has generally higher carbon content compared with fly ash produced from subbituminous coal or lignite, but shows a lower AEA...... methods applied to improve fly ash quality are described in the review. Ozonation, thermal treatment and physical cleaning of carbon have been found to improve the fly ash performance for concrete utilization. Ultimately, recommendations for further work are outlined in the discussion....

  12. Effects of coal fly ash-amended composts on the yield and elemental uptake by plants

    International Nuclear Information System (INIS)

    The objective of this study was to determine the feasibility of coal fly ash-amended composts for use as an alternate manure for agricultural crops. Home-made organic composts was mixed in various proportions with fine fly ash collected from Savannah River Site, and allowed to decompose for two weeks while the mixture was kept wet. Water extracts from the amended composts were analyzed for selected major and trace elements. These amended composts were mixed with sifted sandy loam soil in a predetermined optimum ratio of 1:3 and used to grow corn and sorghum plants. It was shown that fly ash additions to home-made compost facilitated efficient plant utilization of nutrients when 20-40% fly ash in compost was applied to the soil. The maximum dry shoot yields correlated with the higher concentrations of K, Ca and N and lower concentrations of B in the amended compost treatment

  13. Effects of GH Admixture on the Early Strength of Fly Ash Concrete and Mortar

    Institute of Scientific and Technical Information of China (English)

    KANG Jingfu; WANG Xiufen

    2008-01-01

    The enhancement effects of GH admixture on the early strengths of fly ash concrete and mortar were studied, and the mechanism was analyzed by X-ray diffraction (XRD) and scanning electro microscope (SEM). Experimental results show that, by the incorporation of GH admixture, both of cement hydration and pozzolanic reaction of fly ash are accelerated, the strengths of fly ash concrete and mortar are enhanced noticeably, especially the early strength. With a mixture design of 200 kg/m3 OPC (Ordinary Portland Cement), 200 kg/m3 fly ash and 50 kg/m3 GH admixture, the strength of concrete at 1 d, 3 d and 28 d reaches 25 Mpa, 50 Mpa and 70 Mpa respectively.

  14. Combined treatment of SO2 and high resistivity fly ash using a pulse energized electron reactor

    International Nuclear Information System (INIS)

    The combined removal of SO2 and high resistivity fly ash has been demonstrated in a pulse energized electron reactor (PEER). The PEER system which was originally developed for the removal of SO2 utilizes a positive pulse streamer corona discharge in a non-uniform field geometry. In performance tests on SO2, more than 90% was removed with an advantageously small power requirement. Combined treatment performance was demonstrated by introducing high resistivity fly ash into the test gas and the PEER is significantly more efficient than a conventional electrostatic precipitator operated with a dc voltage. Observations show that the PEER agglomerates the fly ash and further that the SO2 removal efficiency is improved by the presence of fly ash. The electrode configuration and performance results make retrofit consideration attractive

  15. Analysis of the Flexure Behavior and Compressive Strength of Fly Ash Core Sandwiched Composite Material

    Directory of Open Access Journals (Sweden)

    Vijaykumar H.K

    2014-07-01

    Full Text Available In this paper, commercially available Fly Ash and Epoxy is used for the core material, woven glass fabric as reinforcing skin material, epoxy as matrix/adhesive materials used in this study for the construction of sandwich composite. Analysis is carried out on different proportions of epoxy and fly ash sandwiched composite material for determining the flexural strength and compressive strength, three different proportions of epoxy and fly ash used for the study. Those are 65%-35% (65% by weight fly ash and 35% by weight epoxy resin composite material, 60%-40% and 55%-45% composite material. 60%-40% composite material specimen shows better results in the entire test carried out i.e. Flexure and Compression. The complete experimental results are discussed and presented in this paper.

  16. Impact Properties of Engineered Cementitious Composites with High Volume Fly Ash Using SHPB Test

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhitao; YANG Yingzi; YAO Yan

    2012-01-01

    The split Hopkinson pressure bar (SHPB) testing with diameter 40 mm was used to investigate the dynamic mechanical properties of engineered cementitious composites (ECCs) with different fly ash content.The basic properties including deformation,energy absorption capacity,strain-stress relationship and failure patterns were discussed.The ECCs showed strain-rate dependency and kept better plastic flow during impact process compared with reactive powder concrete (RPC) and concrete,but the critical compressive strength was lower than that of R-PC and concrete.The bridging effect of PVA fiber and addition of fly ash can significantly improve the deformation and energy absorption capacities of ECCs.With the increase of fly ash content in ECCs,the static and dynamic compressive strength lowered and the dynamic increase factor enhanced,Therefore,to meet different engineering needs,the content of fly ash can be an important index to control the static and dynamic mechanical properties of ECCs.

  17. Study of effect of addition of fly ash on radon exhalation rate in cement samples

    International Nuclear Information System (INIS)

    Most of the building materials like cement and fly ash contain naturally occurring radioactive materials (NORM). Increased interest in measuring radon exhalation rate in building products is due to the concern about health hazards of NORM. This paper focuses on studying the effect of addition of fly ash on radon exhalation rate in cement samples. Ordinary Portland Cement (OPC) and coal fly ash were used for finding the exhalation rate of cement in this paper. To study the effect on exhalation rate of cement, fly ash is added in different proportions to cement samples. The measurement was conducted by CAN Technique using SSNTDs. A gradual increase has been observed in radon exhalation rate up to certain proportion and then start to decrease. (author)

  18. Radium concentration measurements in coal fly ash and cement samples using LR-115 plastic track detectors

    International Nuclear Information System (INIS)

    The increase interest in measuring radium (226Ra) concentration in coal, fly ash and cement is due to its health hazards and environmental pollution. Samples of coal and fly ash from different thermal power stations in northern India were collected and analysed for radium concentration. Cement samples were collected from National Council for Cement and Building Materials (NCB), Ballabgarh (Haryana). The radium concentration is estimated through track etch technique using LR-115 CN detectors. (author)

  19. Method development for determination and recovery of rare earth elements from industrial fly ash

    OpenAIRE

    Perämäki, Siiri

    2014-01-01

    Rare earth elements (REE) are important in numerous high technology applications and in addition their supply risk is high, which gives rise to studying new sources for rare earth elements. Rare earth element concentrations in industrial fly ash samples collected from Finnish power plants, using a mixture of peat and biomass as a fuel, have been determined. Two sample pre-treatment methods, ultrasound- and microwave-assisted acid digestions, have been applied to fly ash samples. Measurement c...

  20. Uses of -Fe2O3 and fly ash as solid adsorbents

    Indian Academy of Sciences (India)

    J Shakhapure; H Vijayanand; S Basavaraja; V Hiremath; A Venkataraman

    2005-12-01

    Solid adsorbents have shown great promise for control of particulate and non-particulate matter and as gas sensing devices in recent times. In the present study, adsorption of environmental toxic pollutant such as lead ions on solid adsorbents viz. -Fe2O3 and fly ash, are reported. Considerable adsorption was observed on fly ash when compared to -Fe2O3 surface. These studies are characterized by employing solid state and solution studies.

  1. Pathological and immunological effects of respirable coal fly ash in male Wistar rats

    NARCIS (Netherlands)

    Dormans, J.A.M.A.; Steerenberg, P.A.; Arts, J.H.E.; Bree, L. van; Klerk, A. de; Verlaan, A.P.J.; Bruijntjes, J.P.; Beekhof, P.; Soolingen, D. van; Loveren, H. van

    1999-01-01

    In this study the effects of inhalatory exposure to coal fly ash on lung pathology and the immune system in rats were examined. Rats were exposed to 0, 10, 30, or 100 mg/m3 coal fly ash (6 h/day, 5 days/wk) for 4 wk, or to 0 and 100 mg/m3 for 1 wk, and for 1 wk followed by a recovery in clean air of

  2. Strategies for Covering Fly Ash Dumps with Plant Species Suitable for Phytostabilization

    OpenAIRE

    Anca Pricop; Smaranda Masu; Benoni Lixandru; Florica Morariu; Neculai Dragomir; Isabelle Laffont-Schwob; Dumitru Popescu

    2011-01-01

    In the context of the revegetation of fly ash dumps, the strategy chosen is very important in order to obtain a vegetal layer that quickly and efficiently covers the fly ash dump, as well as, to allow the wildlife habitat development. The strategy must include: adequate treatments by incorporating fertilizer and amendments, as composts and modified indigenous volcanic tuff; selecting plant species and agricultural work in accordance with geographical and weather conditions. Our in situ experi...

  3. Fresh State and Mechanical Properties of Self Compacting Concrete Incorporating High Volume Fly Ash

    OpenAIRE

    Mohamad N; Zulaika M. S.; Samad A. A. A.; Goh W. I.; Hadipramana J.; Wirdawati A.

    2016-01-01

    Self-compacting concrete is considered as a concrete which can be placed and compacted under its own weight without vibration. The elimination of the need for compaction leads to better quality concrete and substantial improvement of working conditions. This paper investigates the fresh state and mechanical properties of self-compacting concrete incorporating high volume fly ash. Fly Ash (FA) was mixed into self-compacting concrete (SCC) as a replacement for cement. Portland cement (PC) was p...

  4. Monitoring of leachate at a test road using treated fly ash from municipal solid waste incinerator

    OpenAIRE

    Francois, D.; Criado, C.

    2007-01-01

    A treatment process for municipal solid waste incinerator fly ash has been jointly developed by the Université Libre in Brussels and the Solvay company. This experimental process has led to an experimental project with a multi-disciplinary team from Solvay along with several companies and organisations, plus support from the ADEME agency. After a laboratory assessment of the treated fly ash (TFA), its environmental properties and the optimal fields of application in road construction, as part...

  5. Secondary Industrial Minerals from Coal Fly Ash and Aluminium Anodising Waste Solutions

    OpenAIRE

    Nugteren, H.W.

    2010-01-01

    Minerals that are extracted from the earth’s crust to be directly used for their properties are called industrial minerals. This research shows that such minerals can also be produced from industrial residues, hence the name secondary industrial minerals. In this thesis coal fly ash is chosen as one of the industrial residues to work with. Since reuse of coal fly ash is restricted by its technical and environmental quality, the first approach was to improve its quality and thereby extend its ...

  6. Geochemical modeling and assessment of leaching from carbonated municipal solid waste incinerator (MSWI) fly ash.

    Science.gov (United States)

    Wang, Lei; Chen, Qi; Jamro, Imtiaz Ali; Li, Rundong; Li, Yanlong; Li, Shaobai; Luan, Jingde

    2016-06-01

    Municipal solid waste incinerator (MSWI) fly ashes are characterized by high calcium oxide (CaO) content. Carbon dioxide (CO2) adsorption by MSWI fly ash was discussed based on thermogravimetry (TG)/differential thermal analysis (DTA), minerology analysis, and adapting the Stenoir equation. TG/DTA analysis showed that the weight gain of the fly ash below 440 °C was as high as 5.70 %. An adapted Stenoir equation for MSWI fly ash was discussed. The chloride in MSWI fly ash has a major impact on CO2 adsorption by MSWI fly ash or air pollution control (APC) residues. Geochemical modeling of the critical trace elements copper (Cu), cadmium (Cd), zinc (Zn), lead (Pb), and antimony (Sb) before and after carbonation was performed using a thermodynamic equilibrium model for solubility and a surface complexation model for metal sorption. Leaching of critical trace elements was generally found to be strongly dependent on the degree of carbonation attained, and their solubility appeared to be controlled by several minerals. Adsorption on ferrum (Fe) and aluminum (Al) colloids was also responsible for removal of the trace elements Cd, Pb, and Sb. We used Hakanson's potential ecological risk index (HPERI) to evaluate the risk of trace element leaching in general. The results demonstrate that the ecological risk showed a V-shaped dependency on pH; the optimum pH of the carbonated fly ash was found to be 10.3-11, resulting from the optimum carbonation (liquid-to-solid (L/S) ratio = 0.25, carbonation duration = ∼30-48 h). The dataset and modeling results presented here provide a contribution to assessing the leaching behavior of MSWI fly ash under a wide range of conditions. PMID:26965281

  7. Engineering Properties of Concrete Mixed with Varying Degrees of Fly Ash

    OpenAIRE

    Akinola Johnson Olarewaju

    2016-01-01

    The rate of carbon dioxide emission is on the high side globally and very few of this emission are being used. Bulk of this emission comes from cement manufacturing industries. There is urgent need to look for alternatives to cement in other to preserve natural resources globally. This study is aimed at determining the possibility of fly ash as substitute for cement in concrete production. In this study, ordinary Portland cement (OPC) and fly ash were obtained from Lafarge Group Nigeria Limit...

  8. Prediction of the Chloride Resistance of Concrete Modified with High Calcium Fly Ash Using Machine Learning

    OpenAIRE

    Michał Marks; Michał A. Glinicki; Karolina Gibas

    2015-01-01

    The aim of the study was to generate rules for the prediction of the chloride resistance of concrete modified with high calcium fly ash using machine learning methods. The rapid chloride permeability test, according to the Nordtest Method Build 492, was used for determining the chloride ions’ penetration in concrete containing high calcium fly ash (HCFA) for partial replacement of Portland cement. The results of the performed tests were used as the training set to generate rules describing th...

  9. Characterization of Class F Fly Ash Using STXM: Identifying Intraparticle Heterogeneity at Nanometer Scale

    OpenAIRE

    Ha, J.; S. Chae; Chou, K.W.; Tyliszczak, T.; P.J.M. Monteiro

    2016-01-01

    Chemical and physical characterization of fly ash particles were conducted using scanning transmission X-ray microscopy (STXM). Compositional and spatial investigation and correlation among the main elemental constituents of fly ash (Al, Si, and Fe) were conducted based on microscopic and NEXAFS spectral analysis. Homogeneous oxidation and coordination state of Al and Fe were observed whereas Si shows spatial variation in its chemical state. We also identified that Si and Al are spatially cor...

  10. The effect of fly ash and coconut fibre ash as cement replacement materials on cement paste strength

    Science.gov (United States)

    Bayuaji, R.; Kurniawan, R. W.; Yasin, A. K.; Fatoni, H. AT; Lutfi, F. M. A.

    2016-04-01

    Concrete is the backbone material in the construction field. The main concept of the concrete material is composed of a binder and filler. Cement, concrete main binder highlighted by environmentalists as one of the industry are not environmentally friendly because of the burning of cement raw materials in the kiln requires energy up to a temperature of 1450° C and the output air waste CO2. On the other hand, the compound content of cement that can be utilized in innovation is Calcium Hydroxide (CaOH), this compound will react with pozzolan material and produces additional strength and durability of concrete, Calcium Silicate Hydrates (CSH). The objective of this research is to explore coconut fibers ash and fly ash. This material was used as cement replacement materials on cement paste. Experimental method was used in this study. SNI-03-1974-1990 is standard used to clarify the compressive strength of cement paste at the age of 7 days. The result of this study that the optimum composition of coconut fiber ash and fly ash to substitute 30% of cement with 25% and 5% for coconut fibers ash and fly ash with similar strength if to be compared normal cement paste.

  11. Evaluating the Effects of the Kingston Fly Ash Release on Fish Reproduction: Spring 2009 - 2010 Studies

    Energy Technology Data Exchange (ETDEWEB)

    Greeley Jr, Mark Stephen [ORNL; Adams, Marshall [ORNL; McCracken, Kitty [ORNL

    2012-05-01

    On December 22, 2008, a dike containing fly ash and bottom ash at the Tennessee Valley Authority's (TVA) Kingston Fossil Plant in East Tennessee failed and released a large quantity of ash into the adjacent Emory River. Ash deposits from the spill extended 4 miles upstream of the facility to Emory River mile 6 and downstream to Tennessee River mile 564 ({approx}8.5 miles downstream of the confluence of the Emory River with the Clinch River, and {approx}4 miles downstream of the confluence of the Clinch River with the Tennessee River). A byproduct of coal combustion, fly ash contains a variety of metals and other elements which, at sufficient concentrations and in specific forms, can be harmful to biological systems. The ecological effects of fly ash contamination on exposed fish populations depend on the magnitude and duration of exposure, with the most significant risk considered to come from elevated levels of certain metals in the ash, particularly selenium, on fish reproduction and fish early life stages (Lemly 1993; Besser and others 1996). The ovaries of adult female fish in a lake contaminated by coal ash were reported to have an increased frequency of atretic oocytes (dead or damaged immature eggs) and reductions in the overall numbers of developing oocytes (Sorensen 1988) associated with elevated body burdens of selenium. Larval fish exposed to selenium through maternal transfer of contaminants to developing eggs in either contaminated bodies of water (Lemly 1999) or in experimental laboratory exposures (Woock and others 1987, Jezierska and others 2009) have significantly increased incidences of developmental abnormalities. Contact of fertilized eggs and developing embryos to ash in water and sediments may also pose an additional risk to the early life stages of exposed fish populations through direct uptake of metals and other ash constituents (Jezierska and others 2009). The establishment and maintenance of fish populations is intimately associated

  12. Characteristic fly-ash particles from oil-shale combustion found in lake sediments

    International Nuclear Information System (INIS)

    Fly-ash particles accumulate in sediments and can be used to assess spatial distribution and temporal trends of atmospheric deposition of pollutants derived from high temperature combustion of fossil fuels. Previous work has concerned fly-ash derived from oil and coal. Oil-shale is the main fossil fuel used in Estonia and a major source of atmospheric pollution in the Baltic states. To assess if oil-shale power plants produce specific fly-ash particles scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) were used to compare fly-ash particles from oil-shale combustion with particles from oil and coal combustion. Two types were analysed, large black (10-30μm) and small glassy (< 5 μm) spheroidal particles. Although article morphology to some extent is indicative of the fuel burnt, morphological characters are not sufficient to differentiate between particles of different origin. However, the results indicate that with EDX analysis the fly-ash from oil-shale can be distinguished form oil and coal derived particles in environmental samples. Concentrations of large black and small glassy spheroidal fly-ash particles in a sediment core from an Estonian lake showed similar trends to oil-shale combustion statistics from Estonian power plants. 27 refs., 6 figs., 2 tabs

  13. Analysis and design of a stabilized fly ash as pavement base material

    Energy Technology Data Exchange (ETDEWEB)

    A. Hilmi Lav; M. Aysen Lav; A. Burak Goktepe [Istanbul Technical University, Istanbul (Turkey). Faculty of Civil Engineering

    2006-11-15

    The main objective of this study is to utilize a class F fly ash as base material in road pavements. Since class F fly ashes do not manifest desirable engineering properties for this purpose, it was decided to stabilize the material with cement. Fly ash may be utilized with or without aggregate as a pavement layer. It should be noted that, in this research only aggregate free stabilized mixtures (fly ash and cement only) were used since the aim was to utilize high volumes of this waste material. Cement content in the stabilized, laboratory prepared samples were between 2%, 4%, 8%, and 10% by total weight. Initially, Texas triaxial test was carried out to justify the suitability of the fly ash as pavement material. Then, mechanical tests were performed to obtain the fundamental properties of the cement stabilized material in order to analyze the pavement structure. Under repeated wheel loading, fatigue cracking is the primary mode of failure of stabilized materials in which cracks initiate due to the repeated tensile stresses. Utilizing an accelerated full scale road test data for the fatigue performance of cement stabilized fly ash and performing a mechanistic-empirical design procedure, required layer thickness for different lives were obtained for different amount of cement content. 32 refs., 13 figs., 3 tabs.

  14. Destruction of inorganic municipal solid waste incinerator fly ash in a DC arc plasma furnace.

    Science.gov (United States)

    Zhao, Peng; Ni, Guohua; Jiang, Yiman; Chen, Longwei; Chen, Mingzhou; Meng, Yuedong

    2010-09-15

    Due to the toxicity of dioxins, furans and heavy metals, there is a growing environmental concern on municipal solid waste incinerator (MSWI) fly ash in China. The purpose of this study is directed towards the volume-reduction of fly ash without any additive by thermal plasma and recycling of vitrified slag. This process uses extremely high-temperature in an oxygen-starved environment to completely decompose complex waste into very simple molecules. For developing the proper plasma processes to treat MSWI fly ash, a new crucible-type plasma furnace was built. The melting process metamorphosed fly ash to granulated slag that was less than 1/3 of the volume of the fly ash, and about 64% of the weight of the fly ash. The safety of the vitrified slag was tested. The properties of the slag were affected by the differences in the cooling methods. Water-cooled and composite-cooled slag showed more excellent resistance against the leaching of heavy metals and can be utilized as building material without toxicity problems.

  15. The gamma-ray and neutron shielding factors of fly-ash brick materials

    International Nuclear Information System (INIS)

    A comprehensive study of gamma-ray exposure build-up factors (EBFs) of fly-ash brick materials has been carried out for photon energies of 0.015–15 MeV up to a penetration depth of 40 mfp (mean free path) by a geometrical progression (GP) fitting method. The EBF values of the fly-ash brick materials were found to be dependent upon the photon energy, penetration depth and chemical composition, and were found to be higher than the values for mud bricks and common bricks. Above a photon energy of 3 MeV for large penetration depths (>10 mfp), the EBF becomes directly proportional to Zeq. EBFs of fly-ashes were found to be less than or equal to those of concrete for low penetration depths (<10 mfp) for intermediate photon energies up to 1.5 MeV. The EBF values of fly-ash materials were found to be almost independent of Si concentration. The fast neutron removal cross sections of the fly-ash brick materials, mud bricks and common bricks were also calculated to understand their shielding effectiveness. The shielding effectiveness of the fly-ash materials against gamma-ray radiation was lower than that of common and mud bricks. (paper)

  16. Surface mechanical behaviour of composite Ni-P-fly ash/zincate coated aluminium alloy

    International Nuclear Information System (INIS)

    Ni-P-fly ash coatings were produced on zincate coated 5083 wrought aluminium alloy substrates with the aid of an electroless deposition technique. Structural and chemical characterization of the produced coatings was performed with the aid of X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron dispersive X-ray analysis (EDS) techniques. The Ni-P-fly ash coating was found to consist of an amorphous Ni-P matrix with dispersed fly ash particles. The wear resistance of the Ni-P-fly ash coating on zincate treated aluminium alloy was observed to be higher than that of the bare aluminium alloy, when sliding against a stainless steel counterface. In addition, the adhesion between the Ni-P-fly ash/zincate coating and the aluminium alloy substrate was also studied with a scratch testing apparatus. The adhesion strength of Ni-P-fly ash/zincate coating on the aluminium alloy substrate was observed to be higher in comparison to the Ni-P/zincate coating on the same aluminium alloy.

  17. Effect of temperature on the hydration of Portland cement blended with siliceous fly ash

    International Nuclear Information System (INIS)

    The effect of temperature on the hydration of Portland cement pastes blended with 50 wt.% of siliceous fly ash is investigated within a temperature range of 7 to 80 °C. The elevation of temperature accelerates both the hydration of OPC and fly ash. Due to the enhanced pozzolanic reaction of the fly ash, the change of the composition of the C–S–H and the pore solution towards lower Ca and higher Al and Si concentrations is shifted towards earlier hydration times. Above 50 °C, the reaction of fly ash also contributes to the formation of siliceous hydrogarnet. At 80 °C, ettringite and AFm are destabilised and the released sulphate is partially incorporated into the C–S–H. The observed changes of the phase assemblage in dependence of the temperature are confirmed by thermodynamic modelling. The increasingly heterogeneous microstructure at elevated temperatures shows an increased density of the C–S–H and a higher coarse porosity. -- Highlights: •The reaction of quartz powder at 80 °C strongly enhances the compressive strength. •Almost no strength increase of fly ash blended OPC at 80 °C was found after 2 days. •Siliceous hydrogarnet is formed upon the reaction of fly ash at high temperatures. •Temperature dependent change of the system was simulated by thermodynamic modelling. •Destabilisation of ettringite above 50 °C correlates with sulphate content of C–S–H

  18. Restoration of Ecosystems Destroyed by the Fly Ash Dump Using Different Plant Species

    Directory of Open Access Journals (Sweden)

    Florica Morariu

    2013-10-01

    Full Text Available The leguminous plants was studied at experimental variants on fly ash dump: sown species of Onobrichys viciifolia and invasive colonies of Bird's-foot Trefoil (Lotus corniculatus, and yellow sweet (Melilotus officinalis. Six experimental variants were studied in three replicates each: untreated fly ash, fly ash amended with unmodified/modified volcanic rock and fly ash treated with unmodified/modified volcanic rock (indigenous volcanic tuff mixed with organic fertilizer, anaerobically stabilized municipal sludge type. The characteristics of topsoil was assessed in toxic metals Cr, Cu, Pb, Ni content and the characteristics of plants was assessed in terms: height, shoot and roots dry weight, root and shoot ratio, root length density, the aspect plant and competitive ability of this species to dominate in sown habitat. Invasive plants (Lotus corniculatus and Melilotus officinalis have colonized up to 38 - 43 % and max 5 % respectively, treated experimental variants fly ash with organic fertilizer mixed with unmodified/modified volcanic tuff. The proposed strategy with sown leguminous species led to improved conditions for installation of more and resistant invasive species. Furthermore