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Showing papers on "Fly ash published in 1985"


Journal ArticleDOI
TL;DR: In this article, the removal of Cu(II) by adsorption on fly ash has been found to be concentration, pH and temperature dependent, indicating the process to be diffusion controlled.

513 citations


Patent
06 Mar 1985
TL;DR: A binder composition for Portland cement is described in this paper, which includes 100 parts by weight metakaolin and, based upon said metaka-olin, from 20 to 70 part by weight slag; from 85 to 130 parts by value of at least 1 material selected from the class consisting of fly ash, calcined shale, and calcined clay; from 70 to 215 parts by size of finely divided silica, preferably amorphous silica; and from 55 to 145 parts of a mixture of potassium silicate and potassium hydroxide, wherein at least 55 parts
Abstract: A binder composition for Portland cement is disclosed, said composition including 100 parts by weight metakaolin and, based upon said metakaolin, from 20 to 70 parts by weight slag; from 85 to 130 parts by weight of at least 1 material selected from the class consisting of fly ash, calcined shale, and calcined clay; from 70 to 215 parts by weight finely divided silica, preferably amorphous silica; and from 55 to 145 parts by weight of a mixture of potassium silicate and potassium hydroxide, wherein at least 55 parts by weight is potassium silicate. The binder composition can be mixed with Portland cement or with a combination of Portland cement and fly ash to provide a composition curable to a material having a high early strength and a high ultimate strength.

195 citations


Journal ArticleDOI
TL;DR: In this article, 15 polycyclic aromatic hydrocarbons (PAH) adsorbed on silica gel, alumina, fly ash, and carbon black were photolyzed in order to study their atmospheric fate.
Abstract: Fifteen polycyclic aromatic hydrocarbons (PAH) adsorbed on silica gel, alumina, fly ash, and carbon black were photolyzed in order to study their atmospheric fate. Photolytic half-lives for these particle-bound PAH were found to be highly dependent on the substrate to which they were adsorbed. On silica gel and alumina, PAH showed a wide range of photolytic half-lives, indicating a relationship between structure and photochemical reactivity. However, PAH on environmental substrates such as fly ash and carbon black show similar half-lives for most PAH, indicating a photolytic process that is independent of structure and dependent on the physical and chemical nature of the substrate. In fact, fly ash and carbon black appear to stabilize some PAH; this would facilitate their transport from combustion sources through the atmosphere.

189 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that the calcium content and particle size distribution of fly ash are the most important parameters governing the strength development rate in normally cured portland cement-fly ash mixtures.

139 citations


Journal ArticleDOI
TL;DR: In this article, the effects of two fly ashes, a Class C and a Class F, their leachates and leached fly ash residues upon the first 24 hours of cement hydration were studied.

124 citations


Journal ArticleDOI
TL;DR: In this article, measurements of the permeability of saturated, hardened cement pastes, with and without fly ash, were presented from measurements taken from measurements collected from the ground floor of a building.

120 citations


Journal ArticleDOI
01 Mar 1985-Fuel
TL;DR: In this article, the distribution of sodium in different sizes of fly ash produced during coal combustion provides useful insights into the vaporization and condensation mechanisms for sodium, and the departure of the concentration of sodium from an inverse square dependence on particle size can be used to infer the degree of sodium vaporization.

101 citations


Journal ArticleDOI
TL;DR: In this article, a selective dissolution method using a slightly modified picric acid-methanol-water solution procedure was found to be adequate for quantitative determination of unhydrated fly ash and silica fume in hydrated systems of cement-fly ash and cement-silica-fume, respectively.

101 citations


Journal ArticleDOI
TL;DR: INAA results showed that the fly ash between about 0.5 and 8 m was fairly uniform in composition and that the micrometer fume composition was quite different, and the fume was highly enriched in volatile elements such as Ga, As, Sb and Se and depleted in refractory elementssuch as Al, Hf and Sc.
Abstract: Total and elemental mass size distributions from about 10 to 0.04 m were obtained for the fly ash aerosol at the outlet of a pulverised coal utility boiler and upstream of the particulate control device. Elemental data were obtained by instrumental neutron activation analysis and X-ray fluorescence analysis of cascade impactor samples. Submicrometer measurements were also made with an electrical aerosol analyser. INAA results showed that the fly ash between about 0.5 and 8 m was fairly uniform in composition and that the micrometer fume composition was quite different. The fume was highly enriched in volatile elements such as Ga, As, Sb and Se and depleted in refractory elements such as Al, Hf and Sc.

99 citations


Journal ArticleDOI
TL;DR: The results indicate that phytotoxicity of B would be a major problem in establishing vegetation on ash dams and in the agronomic utilization of unweathered fly ashes in Australia.
Abstract: French bean (Phaseolus vulgaris cv. Redland Pioneer) and Rhodes grass (Chloris gayana cv. Pioneer) were grown in glasshouse experiments to examine the potential for phytotoxicity of B in a range of Australian fly ashes. In each experiment, the ashes used were either untreated, leached or adjusted to pH 6.5 and subsequently leached. In the first eperiment, the yield and B status of plants grown on five fly ashes mixed (5 and 10% by weight) with an acid-washed sand were measured and, with the exception of one ash, yield differences among ash sources and among ash treatments were attributed to differences in the degree of B toxicity. In a subsequent experiment, a fly ash with properties representative of most Australian ashes was mixed (0, 15, 30, 70 and 100% by weight) with a sandy loam, and the yield and mineral composition of plants grown on these mixtures determined. Although the available water capacity of the soil was substantially increased by fly ash addition, incorporating large proportions of untreated fly ash resulted in poor plant growth primarily due to B toxicity. In both experiments, leaching the ash reduced the potential for B toxicity, whereas adjustment of the pH to 6.5 and subsequent leaching of the fly ash resulted in plants with normal levels of B. There were marked differences in both the tissue levels of B and the extent of B toxicity symptoms between the two species. Rhodes grass appeared to be able to tolerate higher B contents in the growing medium by taking up much less of the element than French bean. The results indicate that phytotoxicity of B would be a major problem in establishing vegetation on ash dams and in the agronomic utilization of unweathered fly ashes in Australia.

91 citations


Journal ArticleDOI
TL;DR: In this article, a range of pastes of portland cement interground with low-calcium fly ash or granulated blast furnace slag was studied by X-ray diffraction, analytical electron microscopy, thermo-gravimetry, and determinations of CO2 and of unreacted fly ash and slag.
Abstract: A range of pastes of portland cement interground with low-calcium fly ash or granulated blast furnace slag was studied by X-ray diffraction, analytical electron microscopy, thermo-gravimetry, and determinations of CO2 and of unreacted fly ash or slag. Partial replacement of clinker by fly ash results in increased reaction of the alite from at least as early as 3 d. The amount of Ca(OH)2 formed from a given weight of clinker increases at 3 d due to the enhanced reaction, but from 28 d onward, it decreases due to the pozzolanic reaction. The mean Ca/SI ratio of the C-S-H decreases with time or fly ash content, toward a lower limit of ∼1.4. Partial replacement of clinker by slag also decreases both the amount of Ca(OH)2 formed from a given weight of clinker and the mean Ca/Si ratio of the C-S-H, but to a lesser extent. Using the methods described in Part I of this paper, the results of the experimental methods were tested for mutual consistency, and volume percents of phases, porosities, and related quantities were calculated.

Journal ArticleDOI
TL;DR: In this article, surface area measurements and morphology studies on two size-fractionated samples of coal fly ash were performed and it was shown that small ash particles are predominantly non-porous spheres with irregular surface morphology.
Abstract: Results of surface area measurements and morphology studies on 2 size-fractionated samples of coal fly ash show that small ash particles are predominantly non-porous spheres with irregular surface morphology. For the sample taken from a particle collector, it is shown that large surface areas are attributable to carbonaceous particles of highly porous character. It is suggested that the surface area of particles in a coal-fired power plant depends on the point of collection.

Journal ArticleDOI
TL;DR: For the quantitative determination of fly ash in hydrated fly ash - CaSO4·2H2OCa(OH)2 system, various kinds of selective dissolution were evaluated using pastes made from a single representative fly ash as mentioned in this paper.

Journal ArticleDOI
TL;DR: A leaching experiment was designed to evaluate the chemical, mineralogical, and morphological nature of precipitation products formed during the accelerated laboratory weathering of an alkaline fly ash.
Abstract: A leaching experiment was designed to evaluate the chemical, mineralogical, and morphological nature of precipitation products formed during the accelerated laboratory weathering of an alkaline fly ash. The ash, classified as alkaline Modic, was leached with 0.005 mol L⁻¹ H₂SO₄ in a series of five leaching columns for a period of approximately 90 d. The weathered residues were characterized by x-ray diffraction, differential thermal analysis, infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. Three types of precipitation products were identified in the ash. Calcite formed through the dissolution of Ca from the ash and subsequent reaction with CO₂ absorbed by the initial alkaline leaching solutions. Iron, dissolved from the ash under acidic conditions, precipitated as amorphous coatings on fly ash particles. Aluminum and Si dissolved from the glass of the ash was translocated and precipitated within alkaline environments as an amorphous aluminosilicate material best described as proto-imogolite. Results indicated that the products of weathering of fly ash in terrestrial environments are similar to those documented for alkali soils and some soils of volcanic origin.

Patent
14 May 1985
TL;DR: In this paper, a method and means for the stabilization of organic sludges that includes combining the sludge with Portland cement, fly ash, calcium sulfate dihydrate, and lime, optimally with stabilizing agents such as clay, recycled rubber, and asphaltene, and an adsorbent for organic substances.
Abstract: A method and means for the stabilization of organic sludges that includes combining the sludge with Portland cement, fly ash, calcium sulfate dihydrate, and lime, optimally with stabilizing agents such as clay, recycled rubber, and asphaltene, and an adsorbent for organic substances. The stabilized sludge compositions prepared in accordance with this method are characterized by a soil-like consistency and low-volume expansion relative to sludge volumes prior to stabilization.

Journal ArticleDOI
TL;DR: In this article, a fly ash cloud in p.f. furnaces has been found to have an order of magnitude higher complex refractive index than those of pure silica and alumina mixtures, the major constituents of the fly ash particles.

Journal ArticleDOI
01 Feb 1985-Fuel
TL;DR: In this paper, a microscopic method to characterize unburnt char particles in fly ash is proposed, and the char particles are classified into four types (vesicular, dense, mixed and mineral-rich) and categorized into five volumetric size classes (>106, 106−105, 105−104, 104−103, <103μm3).

Patent
28 Oct 1985
TL;DR: In this paper, a closed cell, rigid polyurethane-modified polyisocyanurate foam containing from about 10 to about 80 percent by weight of the foam of fly ash was presented.
Abstract: This invention is a closed cell, rigid polyurethane-modified polyisocyanurate foam containing from about 10 to about 80 percent by weight of the foam of fly ash, which polyurethane-modified polyisocyanurate foam is prepared from a polyurethane-modified polyisocyanurate foam-forming composition which, when foamed to a density of about 1.75 pounds per cubic foot in the absence of the fly ash, forms a foam having a compressive modulus of about 150 to 325 pounds per square inch.

Journal ArticleDOI
TL;DR: In this article, the microstructure of hydrated cement paste varies with distance from an exposed, drying face, and possible causes of the microstructural gradients are discussed in relation to the effects of moisture condition upon cement hydration and pore structure changes and carbon dioxide upon cement hydrates and porosity.

Journal ArticleDOI
TL;DR: In this article, a method for the determination of indium (10 −40 μg g −1 ) in lead-zinc ores and magnetic pyrites was described, using graphite furnace atomic absorption spectrometry with palladium as a matrix modifier.

Patent
24 Jun 1985
TL;DR: In this paper, the authors used dry lime and an aqueous solution of an inorganic salt supplying sulfide, especially an alkali metal sulfide in equimolar quantities.
Abstract: Leaching of cadmium and lead from solid residues obtained in the incineration of refuse may be reduced to environmentally acceptable levels by the addition of calcium sulfide to such residues A particularly convenient method involves the addition of dry lime and an aqueous solution of an inorganic salt supplying sulfide, especially an alkali metal sulfide, in equimolar quantities

Journal ArticleDOI
TL;DR: The molar ratio of potash to alumina (K/A) reflects the relative proportions of illite and kaolinite and is directly proportional to the concentration of pozzolana in PFA as discussed by the authors.

Journal ArticleDOI
TL;DR: In this paper, the concentrations of As, Ca, Cd, Cr, Cu, Fe, Mg, Mn, and Zn as well as physico-chemical parameters were compared for multiple sites in the basin/creek system and a pond without ash inputs from autumn to late summer.
Abstract: Determinations were made of the concentrations of elements in solution and in suspended solids of a settling basin/creek system receiving bottom ash, cyclone ash, fly ash and electrostatic precipitator ash. The concentrations of As, Ca, Cd, Cr, Cu, Fe, Mg, Mn, and Zn as well as physico-chemical parameters were compared for multiple sites in the basin/creek system and a pond without ash inputs from autumn to late summer. Comparison with published results obtained 6 to 7 yr earlier would show no significant change. Chemical speciation calculations indicate that most of the elements remain in the free hydrated or sulfate form throughout the study period. Copper and Fe exhibit some shifts in the concentrations of the hydroxy and carbonate complexes in responses to seasonal and biological factors.

Patent
10 Jan 1985
TL;DR: In this paper, a noxious metal containing waste material is treated with an acid solution of a metal of group Vlla or VIII of the Periodical System, preferably iron or manganese.
Abstract: A noxious metal(s) containing waste material is treated with an acid solution of a metal of group Vlla or VIII of the Periodical System, preferably iron or manganese. Subsequently, the metal of group VIIa or VIII dissolved in the acid is precipitated as a metal hydroxide and simultaneously the noxious metal(s) dissolved from said waste by said acid solution are incorporated in said precipitating metal hydroxide. The waste material together with precipitated metal hydroxide is subjected to an immobilisation treatment. Manganese hydroxide is particularly suitable for removing cadmium. An acid solution of iron and preferably simultaneously manganese to be used for treating the waste is obtained by dissolving oxisludge caught during iron or steel manufacture. The method is particularly suitable for treating dredged harboursludge. The dredged sludge may be formed into granules after mixing with a preformed mixture of the amount of a binder and 50 to 90% of the total amount of fly ash and subsequently the granules are treated with the remaining amount of fly ash. Carbon black and/or a water repellent substance may be added to the remaining amount of fly ash.

Journal ArticleDOI
01 Nov 1985-Fuel
TL;DR: In this article, major and trace element analyses were performed on coals from various locations in western Canada, and on low-temperature (150 °C) and high temperature (1000°C) coal ash produced from these coals.

Journal ArticleDOI
TL;DR: In this article, a range of pores are identified which are particularly susceptible to sulphate attack and a qualitative relationship established between the variation, with curing, of the entry size of these pores, the permeability of the paste and sulphate resistance.

Journal ArticleDOI
TL;DR: The bioavailability of 2,3,7,8-TCDD from municipal incinerator fly ash to freshwater fish was determined in this paper, where it was observed that carp exposed to fly ash containing all 22 TCDD isomers, or the solvent extract of the fly ash, retain only 2, 3, 7, 8 -TCDDD.

Journal ArticleDOI
TL;DR: In this paper, it was found that at least two types of glass co-exist in the fly ash: "Glass I" and "Glass II" glass types associated with high-density particles.
Abstract: Morphological, chemical and mineralogical speciation of fly ash from a power plant burning sub-bituminous coal has been investigated by examination of size and density fractions. It was found that whereas, fractionation by size revealed little information as to speciation among particle types, separation of the ash into six density fractions showed major differences in properties associated with true particle density. In particular it was found that at least two types of glass co-exist in the ash: “Glass I” – a predominantly silico-aluminous glass associated with particles of low density (cenospheres); “Glass II” – a calcium alumino-silicate glass associated with high-density particles. These glasses were found to differ greatly in composition and to be characterized by shifts in the position of the 2-theta of the XRD-halo. In addition, it was shown that cryptocrystalline mullite is associated only with the low-density particles. It is proposed that particles comprising low-density fractions can be considered as glassceramics with low degrees of crystallization. Particles of high-density are better described as the products of internal lime-sinter reactions.

Journal ArticleDOI
TL;DR: In this article, the mechanism of pozzolanic reactions and their control of expansion caused by alkali-aggregate reaction was investigated, and it was shown that pozzolans can reduce or eliminate the expansion of concrete by producing additional calcium silicates hydrate and low lime calcium silicate hydrate.
Abstract: The mechanism of pozzolanic reactions and their control of expansion caused by alkali-aggregate reaction was investigated. Mixtures of tricalcium silicate, opal, sodium hydroxide, and water having calcium oxide to silica mole ratios from 1.07 to 3.0 were prepared and reacted from seven days to four years before filtering. The solids (precipitates) were studied by X-ray diffraction to determine the phases present, and the alkali content of filtrates was obtained by chemical analysis. Results suggest that pozzolans reduce or eliminate alkali-aggregate expansion by producing additional calcium silicate hydrate and low lime calcium silicate hydrate. These hydrates can retain additional alkali, thus reducing the amount of alkali available for reaction with reactive aggregate. In order to control alkali-aggregate expansion by the addition of pozzolan, such as fly ash, results indicate that about 30% low lime fly ash is required. However, this amount could be reduced considerably, to a level as low as 20% (cement basis), if the concrete contains reactive siliceous aggregate.

Journal ArticleDOI
TL;DR: The volumes of the cinders are much larger than those of fly ash and therefore the fate and impact of PCDDs and PCDFs in dump sites of these cinders should be studied.
Abstract: Determination of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in fly ash and cinders collected from nine municipal incinerators in Japan was made. The concentrations of PCDDs and PCDFs in this study were generally in the same range as those in Europe and North America. However, the rather different congener composition compared with those published already were found: higher percentages of lower chlorinated (di- and tri-) dibenzo-p-dioxins and dibenzofurans and no or trace levels of the octachloro compounds, O8CDD and O8CDF. One possible explanation for this difference may be the higher incineration temperature in Japan. The same ranges of concentrations of PCDDs and PCDFs were found in cinders as well as fly ash. The volumes of the cinders are much larger than those of fly ash and therefore the fate and impact of PCDDs and PCDFs in dump sites of these cinders should be studied.