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The work reported in this paper is based on a laboratory study of superplasticized high-volume fly-ash (HVFA) concrete suitable for pavement construction. Three control concrete mixtures having 400 kg/[m.sup.3] of ordinary portland cement (OPC) and watercementitious material (w-cm) ratios of 0.30, 0.34, and 0.40 were prepared. Other concrete mixtures were then prepared by substituting 20, 30, 40, 50, and 60% fly ash in all control mixtures. Compressive and flexural strengths at ages of 7, 28, 90, 180, 256, and 365 days, drying shrinkage, and abrasion resistance of concrete were measured for all the mixtures. The laboratory test results showed that HVFA concrete mixtures containing 50-60% fly ash can be designed to fulfill the requirement of strength and workability suitable for cement concrete pavement construction. At all w-cm ratios, the concrete mixture containing 60% OPC and 40% fly ash developed maximum strength at the age of 90 days and beyond. However, a maximum increase in the strength of concrete at 365 days over the 28 days strength was observed in the mixtures containing equal amount of OPC and fly ash. Drying shrinkage of concrete decreased with decreasing w-cm ratio and increasing fly-ash content. Among all the concrete mixtures, the mixture with w-cm ratio of 0.30 and containing 60% fly ash showed least shrinkage. Abrasion resistance of concrete, measured by the sand-blasting method, decreased with increasing fly-ash content and decreasing compressive strength. However, abrasion resistance of HVFA concrete mixture with 60% fly ash at 0.30 w-cm ratio was adequate from concrete-pavement considerations. DOI: I0.1061/(ASCE)0899-1561(2007)19:10(906) CE Database subject headings: Concrete pavements; Fly ash; Compressive strength; Flexural strength; Shrinkage.

Activation methods and their effects on strength development of nonclinker cements made with 50% cement kiln dust (CKD) and 50% Class F fly ash (FA) were investigated. These activation methods included (1) ball mill cogrinding; (2) chemical (2 and 5% NaOH) addition; and (3) elevated temperature curing (38 and 50[degrees]C). Particle size distribution, hydration products, and compressive strength of the CKD-FA binders were studied. Soluble alkali and chloride content as well as pH value of the CKD-FA pastes were evaluated. The results indicate that all activation methods improved binder strength development. The strength improvement was more significant at the early age than that at the later age. Curing at elevated temperature appeared to be the most effective activation methods compared with grinding and NaOH addition. Combined activation methods provided the binder with higher activation effectiveness than any single activation method. The CKD-FA pastes had much higher alkali and chloride contents but slightly lower pH value than the corresponding portland cement paste. DOI: 10.1061/(ASCE)0899-1561(2007)19:1(112) CE Database subject headings: Fly ash; Portland cements; Dust; Material properties.

This paper presents, by way of comparison, the effect of fly ash on the volume change of two different types of clay, one a highly plastic expansive clay and the other a nonexpansive clay, also of high plasticity. Expansive clays swell on absorbing water and shrink on drying. Nonexpansive clays undergo large compression at high water contents. The effect of fly ash content on free swell index, swell potential, and swelling pressure of expansive clays was studied. Compression index and secondary consolidation characteristics of both expansive and nonexpansive clays were also determined. Swell potential and swelling pressure, when determined at constant dry unit weight of the sample (mixture), decreased by nearly 50% and, when determined at constant weight of clay, increased by nearly 60% at 20% fly ash content. Compression index and coefficient of secondary consolidation of both the clays decreased by 40% at 20% fly ash content. DOI: 10.1061/(ASCE)0899-1561(2007)19:1(67) CE Database subject headings: Fly ash; Soil consolidation; Compression; Swelling.

Abstract: A site-specific study is carried out to assess the suitability of utilizing Atikokan coal fly ash (AFA) as a buffering material to control and mitigate the generation of acid [...]

The aim of this paper is to develop a model for simulating carbonation of fly ash concrete. The model describes the diffusion of gases ([CO.sub.2], and water vapor) in concrete by the mass balance equations and the Fick's law of diffusion. The time dependent hydration, and pozzolanic and carbonation reactions were considered for evaluating the amount of calcium hydroxide in concrete. The rate of carbonation reaction was formulated based on the Arrhenius's formulation. The model was verified by using the results of relative water content, amount of calcium hydroxide, and carbonation depth tested in accelerated and real environments. The influence of changes in parameters on mix proportion and environmental condition were investigated. The verification results were found to be satisfactory in the prediction of carbonation of fly ash concrete. CE Database subject headings: Carbonation; Fly ash; Concrete; Models; Simulation.

This paper reports the findings of experimental studies with regard to some common engineering properties (e.g., grain size, specific gravity, compaction characteristics, and unconfined compression strength) of both low and high calcium fly ashes, to evaluate their suitability as embankment materials and reclamation fills. In addition, morphology, chemistry, and mineralogy of fly ashes are studied using scanning electron microscope, electron dispersive x-ray analyzer, x-ray diffractometer, and infrared absorption spectroscopy. In high calcium fly ash, mineralogical and chemical differences are observed for particles, >75 [micro]m and the particles of CE Database subject headings: Fly ash; India; Grain size; Soil compaction; Compression strength.

When conventional concrete is used in congested drilled shafts, coarse aggregates may bridge between reinforcing bars, which may lead to segregation of the concrete between the inside and outside of the reinforcing cage. The use of self-consolidating concrete (SCC) was evaluated to overcome this problem. The purpose of this study was to compare conventional drilled shaft concrete and SCC in a drilled shaft application. This paper reports on the data collected during the construction and evaluation of five drilled shafts that were 1.0 m in diameter and 7.3 m deep. Three shafts were constructed with conventional drilled shaft concrete and two shafts were constructed with SCC. The five shafts were exhumed, cleaned, and visually inspected to evaluate the quality of the as-built concrete. Cross sections of the exhumed shafts were cut in order to observe the uniformity and the amount of segregation between the inside and outside of the cage. Based on the results of this project, it is concluded that SCC may be feasible for use in congested drilled shaft applications. CE Database subject headings: Concrete; Drilled shafts; Field tests; Fly ash; Slag.

ABSTRACT If a municipal solid waste (MSW) landfill is used as the foundation for a construction site, the change in the loading conditions may cause considerable compression of the landfill. [...]

In this paper, the influence of ultrafine fly ash on the early age property development, shrinkage, and shrinkage cracking potential of concrete is investigated. In addition, the performance of ultrafine fly ash as cement replacement is compared with that of silica fume. The mechanisms responsible for an increase of the early age stress due to restrained shrinkage were assessed; free shrinkage and elastic modulus were measured from an early age. In addition, the materials resistance to tensile fracture and increase in strength were also determined as a function of age. Results of the experimental study indicate that the increase in elastic modulus and fracture resistance with age are comparable for the control, ultrafine fly ash, and silica fume concretes. Autogenous shrinkage is shown to play a significant role in determining the age of cracking in restrained shrinkage tests. A significant reduction in the autogenous shrinkage and an increase in the age of restrained shrinkage cracking were observed in the ultrafine fly ash concrete when compared with the control and the silica fume concrete. Increasing the volume of ultrafine fly ash and decreasing the ratio of water-to-cementitous materials resulted in further increase in the age of restrained shrinkage cracking and a significant increase in the compressive strength. DOI: 10.1061/(ASCE)0899-1561(2005)17:1(45) CE Database subject headings: Fly ash; Concrete; Shrinkage; Cracking; Material properties.

The long-term disposal of ash from brown coal combustion requires a thorough understanding of the geochemical controls on leachate quality. The geochemistry of leachate in ash generated from the combustion of coal in the Latrobe Valley region of Victoria, Australia, has been studied in the field and laboratory. The field studies, conducted over 14 months, showed active leaching and changes in leachate chemistry in the ash with mobilization of some trace elements. A further series of laboratory columns demonstrated similar leaching dynamics. Geochemical modeling indicated that both sulfate and carbonate minerals are the most likely solubility-controlling mineral phases in the ash. For regularly detected trace elements, such as As, Ba, and B but particularly Mo, Se, and Sr, the trends suggest that adsorption and coprecipitation controls are also important. The overall approach adopted in this paper has enabled a more realistic assessment of the controlling processes for solute transport during the active leaching phase of ash disposal, thereby improving long-term environmental management. DOI: 10.1061/(ASCE)0733-9372(2004)130:12(1514) CE Database subject headings; Fly ash; Environmental impacts; Leaching; Waste disposal; Australia; Coal.

Detailed testing regarding geotechnical utilization was carried out on fly ash from the Dadri thermal power station. The chemical composition and physical properties of the fly ash were determined. The morphology of the fly ash particles was studied by scanning electron microscopy. An X-ray diffraction test was also conducted. The geotechnical testing program included the classification tests, the compaction test, the consolidation test, and the permeability test. The influence of the head loss across the specimen, the effective stress, and the void ratio on the permeability was studied. The paper explains the details and results of the tests, especially those of the consolidation and permeability behaviors. The results showed that the coefficients of permeability and consolidation of the compacted fly ash were comparable to those of nonplastic silts. The variation in head loss across the specimen had only a small influence on the coefficient of permeability. Even at a high effective stress there was no appreciable reduction in the coefficient of permeability. The consolidation and permeability characteristics of the Dadri fly ash have been compared with those of some other Indian fly ashes. The geotechnical utilization of the Dadri fly ash has been explained through illustrative examples. DOI: 10.1061/(ASCE)0733-9453(2004)130:1(18) CE Database subject headings: Compaction; Consolidation; Fly ash, Laboratory tests; Permeability; Shear strength.

The potential of a concrete for carbonation can be assessed effectively by measuring its carbonation depth using an accelerated carbonation testing. This paper reports the findings of a laboratory study including compressive strength, accelerated carbonation depth, and porosity properties of concrete mixtures made with fly ash and normal portland cement. The study involves two replacement ratios of fly ash, various water-to-cement ratios, use of superplasticizer, two curing conditions, and four concrete ages. Statistical models that relate accelerated carbonation depth to strength and porosity are presented. DOI: 10.1061/(ASCE)0899-1561(2004)16:1(91) CE Database subject headings: Carbonation; Porosity; Fly ash; Concrete; Strength.

The effectiveness of several Class C and Class F fly ashes in controlling expansion due to alkali silica reactivity (ASR) was investigated based on a modified ASTM C 1260 test method. Three different strengths of NaOH solution (1N, 0.5N, and 0.25N) were used to test the reactivity of reactive and potentially reactive aggregate in mortars with 20 and 35% Class C and F fly ash replacements by mass of cement. The other variables included high and low alkali cement, extended curing time, and longer testing period of 28 days. Test results confirm that Class F fly ash is more effective than Class C fly ash in controlling expansion due to ASR, but that Class C fly ash can also be used under certain conditions. CE Database subject headings: Fly ash; Alkalinity; Cements; Expansion.

This paper investigates the use of fly ash as a replacement for sand in polymer concrete (PC). It is shown that a replacement of 15% by weight of sand with fly ash improves the compressive strength of unreinforced PC cylinders by about 30% and the flexural strength of steel-reinforced PC beams by about 15%. Other improvements in properties are relatively minor and include the tensile bond strength of PC under thermal cycling and the creep compliance of the PC under sustained loading. The replacement of sand with fly ash, however, does not seem to have an impact on the shear strength of PC. Potential applications of PC using fly ash are numerous, including thin overlays on bridges and floors, repairing concrete bridges and pavements, and the production of precast components such as wall panels, floor blocks, and underground vaults. CE Database subject headings: Polymer concrete; Fly ash; Recycling; Compressive strength; Flexural strength; Shear strength; Bonding strength.

Fly ash from a coal-fired power plant was investigated to obtain detailed information on its physical and chemical properties, and to gain an understanding of potential environmental and health impacts associated with its disposal in landfills. The studied material was produced through combustion of Illinois Basin coal and trapped within the power plant by an electrostatic precipitator. It is a fine-grained, low-Ca fly ash containing primarily Si[O.sub.2], [Al.sub.2][O.sub.3], and [Fe.sub.2][O.sup.3], and is enriched in many toxic elements (e.g., Be, Zn, As, Cd, Tl, Pb, and U) by a factor of up to 30 relative to coal. The ash consists of mainly hematite, magnetite, mullite, quartz, and amorphous material. These constituents occur mostly as spherical particles with diameters of less than 13 [micro]m. We examined the physical, chemical, and structural characteristics of individual fly ash particles by scanning and transmission electron microscopy and electron probe microanalysis. The results demonstrate that, with the exception of complex plerospheres, individual particles are chemically fairly homogeneous, but a pronounced compositional variation exists among particles with similar physical and structural attributes. Electron microprobe data document that several trace elements, including U, are partitioned into the Ferich particles. Transmission electron microscopy revealed that various types of small (

The Florida Department of Transportation (FDOT) requires contractors for FDOT's projects to submit a proposed concrete mix design prior to the production of any concrete. The contractor must use mix designs approved by FDOT. Substitutions of ingredients other than coarse aggregate must be justified through trial mixtures, and authorized in writing by FDOT engineers. The study reported herein investigated whether substitutions of fly ash, slag, air-entraining admixtures, and Types A, D, and G admixtures could be performed and be allowed in FDOT approved concrete mix designs. Substitutions of the ingredients were performed on two typical FDOT hot weather mix designs in this study. The concrete properties considered were slump, air content, and compressive strength. Test data for substitution mix designs were compared with the data for the original mix design. Results show that the substitutions cause variability in concrete properties for both the fly ash and the slag mix designs. Statistically reliable conclusions cannot be made because of small sample sizes for test data sets. This study is preliminary in nature; more extensive research based on statistically significant sample sizes is needed to validate the findings from this study. CE Database subject headings: Fly ash; Slag; Admixtures; Concrete; Design; Florida.

Fly ash is a waste produced in coal-fired thermal power stations. It has pozzolonic properties and can therefore be stabilized with either cement or lime to achieve the strength required for use as base courses in pavements. Agencies such as the Electric Power Research Institute (EPRI) have specified criteria and guidelines for the determination of the stabilizer content. This requires carrying out unconfined compression tests on stabilized fly ash specimens prepared and cured as per standard procedures. The stabilizer content is the minimum amount of the stabilizer for which the unconfined compressive strength of the specimens complies with the specified values. The actual curing conditions of the stabilized fly ash bases in the field, however, will differ from those of the laboratory specimens. This will affect the strength development of the bases, their durability, and their performance. The paper explains the details and results of a laboratory experimental program carried out to study the influence of curing conditions and other factors on the development of strength. The program comprised compaction tests and unconfined compression tests. Two Indian fly ashes and a commercial portland cement were used in the study. Six different curing conditions, including controlled and ambient conditions, were adopted. The influence of differences in the dry unit weight and water content was also investigated. DOI: 10.1061/(ASCE)0733-947X(2003)129:5(538) CE Database subject headings: Fly ash; Base courses; Cements; Pavements; Stabilization.

One of the ways in which highly urbanized cities cope with increasing amounts of municipal solid waste (MSW) generated by the population is incineration. As land is a very precious commodity and landfills are fast dwindling in most highly urbanized cities, the disposal of the ash generated from MSW incineration poses increasingly difficult problems for the municipalities. A viable solution to the disposal problems would be the reuse of MSW ash for civil engineering applications. A research study of the properties of the incinerator fly ash derived from MSW incineration indicated that fly ash is a potential source of jet-grouting admixture for soil improvement. The fly ash exhibits a likelihood of pozzolanic reaction due to its chemical composition and physical characteristics. The use of fly ash as an admixture in the stabilization of a soft marine clay resulted in stabilized samples with an improved strength more than 75 times that of the untreated clay. Incorporation of fly ash also improved drainage property by at least one order of magnitude and reduced both the plasticity and compression indices by about 69 and 23%, respectively. Leachate investigation conducted on the fly ash-stabilized soils indicated that chromium was well-below the World Health Organization drinking water limit, while nickel and lead were in excess of the limits. The nickel and lead leachate concentrations diminished to below the acceptable drinking water limits over a period of about 130 and 110 days, respectively. CE Database subject headings: Admixtures; Fly ash; Solid wastes; Soil stabilization; Recycling.

This investigation was performed to develop technology for manufacturing cast-concrete products using Class F fly ash, coal-combustion bottom ash, and used foundry sand. A total of 18 mixture proportions with and without the by-products was developed for manufacture of bricks, blocks, and paving stones. Replacement rates, by mass, for sand with either bottom ash or used foundry sand were 25 and 35%. Replacement rates, by mass, for portland cement with fly ash were 25 and 35% for bricks and blocks, and 15 and 25% for paving stones. Analysis of test data revealed that bricks with up to 25% replacement of cement and blocks with up to 25% replacement of cement and sand with recycled materials are suitable for use in both cold and warm climates. Other bricks and blocks were appropriate for building interior walls in cold regions and both interior and exterior walls in warm regions. Paving stones with 15% replacement of cement with fly ash showed higher strength, freezing and thawing resistance, and abrasion resistance than the control specimens. CE Database subject headings: Recycling; Fly ash; Sand; Concrete, precast; Bricks; Stones.

Byline: Dharmendra K. Gupta (1), Upendra N. Rai (2), Rudra D. Tripathi (2), Masahiro Inouhe (1) Keywords: Bioremediation Environmental pollution Fly-ash Heavy metal tolerance Nitrogen fixation Abstract: Coal combustion produces carbon dioxides, SOx, NOx and a variety of byproducts, including fly-ash, flue gas and scrubber sludge. Fly-ash consists of minute glass-like particles and its deposition on leaves inhibits the normal transpiration and photosynthesis of plants. Fly-ash also affects the physicochemical characteristics of soil because it is generally very basic, rich in various essential and non-essential elements, but poor in both nitrogen and available phosphorus. The massive fly-ash materials have been a potential resource for the agricultural activities as well as the other industrial purposes. Practical value of fly-ash in agriculture as an 'effective and safe' fertiliser or soil amendment can be established after repeated field experiments. Here remains to be disclosed the biological processes and interactions due to 'lack and excess' of the fly-ash exposures along with abiotic and biotic factors. These may involve the symbiotic fixation of nitrogen and the biological extraction of metals following immobilisation of toxic heavy metal ions, as well as other neutralisation and equilibration processes during weathering. Nitrogen-fixing plants with an apparent heavy metal-tolerance can be helpful as the early colonisers of fly-ash dumps and nearby areas. Author Affiliation: (1) Department of Biology and Earth Sciences, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan (2) Ecotoxicology and Bioremediation Group, National Botanical Research Institute, Lucknow, India Article History: Received Date: 03/06/2002 Accepted Date: 16/08/2002 Article note: Electronic Publication

Removal of zinc-rich ash and mercury from a gas stream using prototype electrostatic precipitators (ESPs) has been investigated. Dust particles collected from the thermal plasma ash volume reduction system of the Matsuyama, Japan, municipal incineration plant were used to study the performance of an ESP to collect zinc-rich ash. The ash was analyzed by neutron activation analysis using the nuclear reactor at McMaster University, Hamilton, ON, Canada. Collection efficiency as high as 99.9% was obtained in the removal of Zn from the flue gas with dc energization of the ESP. The mercury concentration was measured using a cold vapor atomic absorption spectrometer after sampling (OSHA-140 method) from the flue-gas stream. As a function of concentration, the mercury collection efficiency was higher at a higher concentration of mercury. Higher collection efficiency was obtained under negative dc energization compared to other modes of energization of the ESP; however, power consumption under the pulse application was much smaller compared to dc energization. Index Terms--Coal-fired power plant, electrostatic precipitator, fly ash, flue gas, mercury, particle charging, particulate contamination, pulse power, trace elements, zinc.

This study was used to examine fly ash from Belgium in terms of its behaviors with regards to thermal polychlorodibenzo-p-dioxins and polychloridebenzofurnas formation. The article is broken down into an introduction, a discussion of the experiment and a discussion of the results. Various tables and graphs accompany the article.

This study examines the PCCD/F (polychlorinated dibenzo-p-dioxins/furans) emissions at a 10 kg h(super-1) pilot scale incinerator burning medical waste. The model of PCCD/F formation that was developed for the chlorine-rich gas phase was based on the diffusion of HCl to the fly ash surface.

A research report examines the effectiveness of an iron, sand, and bentonite barrier used to immobilize chromium in coal fly ash.

The electrical and electrochemical characteristic of pyrolized fly ash, which has a porous structure, is investigated for use as an electrode active material in rechargeable batteries. The investigation shows that electrodes of pyrolized fly ash show good stability and high Coulombic efficiency in charge-discharge cycles of LiClO4/PC.

Microstructural, chemical, mineralogical, and thermal analysis was carded out in a study to use Eraring Power Station (New South Wales, Australia) fly ash as pavement base material. The fly ash was stabilized with cement and lime separately. The effects of cement and lime stabilization were examined in terms of chemical composition, crystalline structures, and hydration products. Unconfined compressive strength of samples was also measured to observe the effect of stabilization over time. The results obtained from cement and lime-stabilized samples showed that the hydration products that account for strength gain of the stabilized fly ash are almost the same for both types of stabilizing agents. The discrepancies between the resulting strengths are due to the proportion and density of these products.

This paper investigates the effect of time on the shear strength and the permeability of fly ash, a major solid by-product of thermoelectric power plants. Direct shear tests using Mikasa's apparatus, conventional permeability tests, and consolidation tests were conducted on two silt-size fly ashes, with low free lime contents, obtained from two different power plants. The results show that the immediate settling of both fly ashes takes place in a short period of time during consolidation and does not change with time. The rate of increase in shear strength with time is different depending on the pozzolanic reactions taking place for the two ashes. The permeability tests under constant stresses of 49 and 98 kPa for 12 days show that the coefficient of permeability for the tested ashes is between 10(super -6) and 10(super -7) m/s. During this period the coefficient of permeability either remains constant (for the case of the ash with a lower free lime content) or is slightly reduced (for the ash with a higher free lime content). The practical implications and the limitations of using low lime silt-size fly ash in vertical drains in the stabilization of soft ground are also discussed.

Tests on composite material from high-lime (ASTM class C) fly ash and recycled polyethylene terephthalate (RPET) were conducted to investigate the physiomechanical properties and microstructure features. Composite specimens with varying fly ash concentrations were tested in compression and tension, immersed in water to measure water absorption, and observed for shrinkage during manufacturing. Theoretical equations from modulus of elasticity and tensile strength were derived with values compared to portland cement concrete. Microstructural features associated with crack propagation during compression loading and the RPET binding mechanism were studied utilizing scanning electron and polarized reflective light microscopy and differential scanning calorimetry. The results of this investigation showed that the fly ash concentration contributed significantly to both the strength of composite material and the crystallinity of the RPET binder. Based on the evidence, it was concluded that the composite material is a value-added material with a variety of potential construction applications.

Finnish researchers discuss a method for detecting arsenic, cadmium, mercury, nickel, lead, selenium, vanadium, and zinc in ash, and flue gas of coal-fired electric generator plants. Tables and figures accompany the article.

This paper presents experimental results on porosity and pore size distribution of fly ash and silica fume modified cement pastes and mortars using mercury intrusion porosimetry. It is found that replacement of cement by fly ash increases the porosity but decreases the average pore size of the pastes at the ages of 28 and 56 days. The additional replacement of cement by up 5% silica fume did not significantly change the pore size distribution and porosity of either the plain cement pastes or the fly ash cement pastes. Interfacial porosity, however, was significantly influenced by incorporating fly ash and silica fume in the mortars. The interfacial porosity was much reduced when fly ash and silica fume were incorporated. Compared with the porosity and average pore size of the pastes and mortars, the interfacial porosity better explains the results of a chloride diffusion test of the fly ash and silica fume concrete in most cases. However, for the concrete with 55% fly ash replacement at 28 days, the drop of ionic concentration of the pore solution seems to be more responsible for the low result of coulomb passed in the test.

Researchers investigated a means for removing heavy metals and other elements from fly ash produced by burning forest material. The test was performed in a fluidized bed boiler based in Sweden. Laser diffraction was used to determine the size of fly ash particles. Elements were found at different amounts and particulate size depending upon where samples were taken from the boiler. Bottom ash in 830 degrees C contained less of the elements than the coarse fly ash. Some elements, like zinc, were found only in the coarse fly ash.

Energy is important for modern civilization and the electrical power from thermal stations is a major source of energy on which hinges the functioning and growth of mankind. In almost all major countries of the world thermal power stations are getting bigger and are generating huge quantities of flyash as a waste from their mammoth boilers. Despite extensive research on flyash, its utilization level is still low although it is considered as a novel and useful material in various fields such as building and road construction, agriculture, refractory works, water treatment, foundry, etc. In the present work flyash has been used as an additive to the silica sand in the V-process molds and its effects on the surface finish and total solidification time of the Al-11%Si alloy castings have been studied. Results indicate that the surface finish of the castings improves by the addition of flyash. Total solidification time of the castings reduces when the flyash has been added beyond 25 percent.

A semicontinuous laboratory-scale leaching plant (LSLP) is described. A mixture of Thiobacillus ferrooxidans oxidizing reduce metal compounds and Thiobacillus thiooxidans generating sulfuric acid was utilized in the performance of the leaching experiments. The three-step LSLP experiment suggest the practicability of biotic fly ash leaching despite the presence of saline and strongly alkaline material. A scaled-up version of the LSLP seems to be technically feasible in metal-manufacturing industries.

Calcium hydroxide is much more effective than other mineral sorbents such as silica, kaolinite and alumina in capturing arsenic. The mechanism of the capture was investigated using hydrated lime sorbent, and it was determined that an irreversible chemical reaction occurs between arsenic and calcium hydroxide, resulting in a solid product. The capture does not occur as the result of sorption, which is the mechanism of arsenic capture using fly ash.