Showing papers on "Fly ash published in 1984"
TL;DR: In this paper, a microwave oven in the presence of acid mixtures dissolves the metals from powdered coal, fly ash, oil shales, rocks, sediments, and biological materials.
Abstract: Heating in a microwave oven in the presence of acid mixtures dissolves the metals from powdered coal, fly ash, oil shales, rocks, sediments, and biological materials. The dissolution is complete within 3 min. Nearly 25 elements (Al, As, Ba, Be, Ca, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, P, Pb, Si, Sr, Tl, V, and Zn) from the dissolved samples are determined by inductively coupled plasma emission spectrometry. The method has been tested on a variety of standard reference materials, with reproducible and accurate results.
277 citations
TL;DR: In this article, the nutritional status of fly ashes from Australian power stations was assessed on samples leached with water to reduce the soluble salts to equilibrium levels, and the results are discussed with reference to the establishment of vegetation on ash dumps and to the use of fly ash in ameliorating the properties of soils.
Abstract: Of the 13 fly ashes from Australian power stations, all were dominated by both amorphous and crystalline aluminosilicates and quartz, and these were associated with minor amounts of Fe oxides, lesser amounts of Ca, Mg, Na, K, Ti and P oxides, and variable levels of incompletely combusted C. The ashes consisted of particles predominantly in the silt plus fine sand fraction (67-98%), and electron microscopy revealed that ash matrices consisted of glassy spherical particles and less regularly shaped spongy particles. The available water capacity was high and varied from 27 to 105% with 11 of the 13 samples having values > 40%. Twelve of the 13 ashes were alkaline to strongly alkaline (pH range 8.0-12.8). Soluble salt levels were related to the coal source, and electrical conductivity of the saturation extracts (ECse) varied from 0.63 to 7.0 mS cm -1 for 11 of the samples; two ashes produced from brown coal had ECse values of 46.0 and 55.0 mS cm-1. The nutritional status of the ashes was assessed on samples leached with water to reduce the soluble salts to equilibrium levels. The ashes contained negligible amounts of N, but their P status was variable. The amounts of NH4OAc-extractable Ca and Mg were generally high in most samples and were considered more than adequate for most plant species; however, NH4OAc-extractable K values were generally low. Adequate levels of sulfate-S existed in 12 of the 13 samples, and levels of DTPAextractable Cu, Zn, Mn and Fe were high when compared with published critical values. Most of the unleached samples contained potentially toxic levels of B. The results are discussed with reference to the establishment of vegetation on ash dumps and to the use of fly ash in ameliorating the properties of soils.
115 citations
Patent•
07 Nov 1984
TL;DR: In this article, a light-weight aggregate, for use in production of lightweight structural products, composed of a self-hardening fly ash, a surfactant foam, and optionally an accelerator and additives, is presented.
Abstract: A light-weight aggregate, for use in production of light-weight structural products, composed of a self-hardening fly ash, a surfactant foam, and optionally an accelerator and additives. The self-hardening fly ash is preferably class C fly ash formed by the combustion of sub-bituminous coal from the Power River Basin. The surfactant foam is preferably an anionic sulfate surfactant foam. The accelerator is preferably an extract of silica fume dust. The additives may include magnesium and boron compounds, other fly ashes, light-weight fillers, polymers, cement and magnesium silicate and like materials.
99 citations
TL;DR: In this paper, fly ash specimens from North Dakota, Wyoming and Montana lignite and sub-bituminous source coals have been studied in detail by X-ray diffraction.
83 citations
TL;DR: In this paper, the authors used x-ray diffraction, differential thermal analysis (DTA) and scanning electron microscopy (SEM) to study the pozzolanic activity of fly ashes.
67 citations
TL;DR: A column leaching experiment designed to evaluate the relationship among leachate properties, weathering processes, and solid phase characteristics of an alkaline fly ash was conducted in this paper. But the results of the experiment were limited.
Abstract: Results are presented for a column leaching experiment designed to evaluate the relationship among leachate properties, weathering processes, and solid phase characteristics of an alkaline fly ash. Fly ash was weathered with 0.005 mol/L H₂SO₄ in a series of five leaching columns. Acidification of the ash leachates occurred in a stepwise fashion involving three buffer stages. Chemical dissolution and mobilization of elements was greatest in the first column and decreased to minimal dissolution and maximum accumulation of weathered products in ash of the fifth column. Results indicated that unreacted fly ash consists of spherical micron-sized particles composed of mullite enclosed in a two-phase glassy matrix. The external glass was enriched in Ca, Mg, Fe, and Al. The interior glass matrix was composed primarily of Si and a major portion of the total Na and K. The ash also contained a highly reactive inorganic phase composed largely of submicron-sized CaO fragments on the surfaces of ash particles. Initial dissolution characteristics were dictated by the reactions of the CaO fragments and surface-associated soluble salts. Leachate characteristics were largely controlled by dissolution of the external glassy matrix after the rapid dissolution of surface salts. Solid state migration and removal of Na from the interior glassy matrix was active under acidic leaching conditions.
67 citations
TL;DR: In this article, the Illinois Basin fly ash samples were each mixed with deionised water and equilibrated for about 140 days to simulate ash ponding environment, and the pH of the extract of the acidic fly ash was 4.1 after 24 h, but increased to a pH of 6.4 as the H/sub 2/SO/sub 4/, assumed to be adsorbed to the particle surfaces, was exhausted by the dissolution of matrix iron oxides and aluminosilicates.
Abstract: Alkaline and acidic Illinois Basin fly ash samples were each mixed with deionised water and equilibrated for about 140 days to simulate ash ponding environment. The pH of the extract of the acidic fly ash was 4.1 after 24 h, but increased to a pH of 6.4 as the H/sub 2/SO/sub 4/, assumed to be adsorbed to the particle surfaces, was exhausted by the dissolution of matrix iron oxides and aluminosilicates. The activities of aqueous Al/sup 3 +/ and iron, initially at high levels, decreased to below analytical detection limits. The pH of the extract of alkaline fly ash remained above a value of 10 during the entire equilibriation interval. The Al/sup 3 +/ activities were controlled by amorphous aluminium hydroxide phases that began to form after about 7 days of equilibration. The proposed mechanisms are discussed.
65 citations
TL;DR: The data reported in this paper effectively complete the description of the chemical speciation of the elements in a set of four stack-collected coal fly ash samples which have been used extensively in the determination of the biological effects of coalFly ash.
Abstract: The data reported in this paper effectively complete the description of the chemical speciation of the elements in a set of four stack-collected coal fly ash samples which have been used extensively in the determination of the biological effects of coal fly ash. The association of elements with the aluminosilicate glass or surface salts, the association of cations and anions of the surface of ash particles, and the oxidation states of nonmetal and transition metals are discussed. 27 references.
64 citations
TL;DR: Stack-collected coal fly ash from western low-sulfur coal was extracted with 60:40 benzene/methanol and the mutagenic activity of 14 fractions was evaluated by microbial assay with Salmonella typhimurium TA1538, which indicated a widespread distribution of direct-acting mutagens.
Abstract: Stack-collected coal fly ash from western low-sulfur coal was extracted with 60:40 benzene/methanol. This extract was fractionated by preparative-scale high performance liquid chromatography (HPLC) and the mutagenic activity of 14 fractions was evaluated by microbial assay with Salmonella typhimurium TA1538. A widespread distribution of direct-acting mutagens, which probably includes both mono- and dinitroaromatics, was detected. HPLC methods were also used to isolate 1-nitropyrene from the total benzene/methanol extract. The identification of 1-nitropyrene was based on gas chromatographic and HPLC retention measurements and mass spectral data. The concentration of 1-nitropyrene in the ash extract was determined by quantitative HPLC analyses. Mutagenicity assays of the total extract and an authentic 1-nitropyrene standard with Salmonella strains TA1538, TA100, and TA98 indicated that the 1-nitropyrene accounts for approximately 0.03-0.16% of the total mutagenic activity of the extract.
56 citations
TL;DR: In this article, an extensive laboratory study of air-entrained high fly ash concrete mixes (air entrained and non air entrained) of medium to low workability suitable for placement by slipforming and roller compaction, respectively, was conducted.
Abstract: Concretes containing fly ash up to 75 percent by weight of the cementitious material have properties that make them attractive as a subbase or base course component in pavement construction. This paper describes an extensive laboratory study of air-entrained high fly ash concrete mixes (air entrained and non-air entrained) of medium to low workability suitable for placement by slipforming and roller compaction, respectively. The concretes were characterized as to their compressive, indirect tension, and flexural strengths; drying shrinkage; and freeze-thaw durability. It is confirmed that cohesive nonsegregating concretes can be manufactured containing 40 to 75 percent fly ash in the cementitious fraction.
50 citations
TL;DR: In this paper, the inorganic chemical composition of fly ash effluent is time dependent and may be most toxic to aquatic ecosystems when initially mixed with water and pumped to disposal ponds.
Abstract: Twelve precipitator-collected fly ash samples (9 from high-S Illinois Basin coals and 3 from western US coals) were found to contain a variety of paraffins, aryl esters, phenols and polynuclear aromatic hydrocarbons, but all at very low concentrations. Solubility studies with a short-term (24 h) extraction procedure and a long-term (20 week) procedure indicate that the inorganic chemical composition of some types of fly ash effluent is time dependent and may be most toxic to aquatic ecosystems when initially mixed with water and pumped to disposal ponds. Some acidic, high-Cd fly ashes would be classified as hazardous wastes if coal ash was included in this waste category by future revisions of the US Resource Conservation and Recovery Act (RCRA).
TL;DR: Small fly ash settling ponds (e.g. 2-yr life time) should be used after they are ~87–90% full when effluents are released into lotic systems, and which fraction of fly ash is most limiting to each insect group or species needs far more examination.
Abstract: Small fly ash settling ponds (e.g. 2-yr life time) should not be used after they are ~87–90% full when effluents are released into lotic systems. When our pond was > 90% full, mayflies (Stenonema, ...
TL;DR: In this paper, the effect of fly ash particles on stomatal plugging was examined both in the field and in the laboratory, and it was shown that the stomata of two experimental plants, Phaseoulus vulgaris and Zea mays, did not become plugged by fly ash from a power plant.
TL;DR: In this paper, the state of these various methods, current results of their use in rly ash characterizations, and the relations of these to reactivity and performance of fly ashes in cement and concrete are discussed.
Abstract: Fly ashes are currently being produced that are much more widely different from each other in composition and other characteristics than had been previously experienced, owing to the widespread use of low rank subbituminous and lignitic coals. The current ASTM classifications into Class F and Class C pozzolan categories are not adequate to describe all their important properties. Current characterization methods are reviewed, including physical characterization by particle size distribution, shape, apparent specific gravity, content of hollow grains and of residual coal fragments, etc., chemical procedures of various kinds, and SEM, EDXA, XRD, and other methods for the determination of mineralogical content and glass character. Etching and chemical dissolution procedures are particularly important. The state of these various methods, current results of their use in rly ash characterizations, and the relations of these to reactivity and performance of fly ashes in cement and concrete are discussed.
TL;DR: In this paper, unweathered, acidic fly ash from a coal-fired power plant was applied to alfalfa meal-amended agricultural soil at levels equivalent to 0, 100, 400, and 700 tonne ha−1.
Abstract: Unweathered, acidic fly ash from a coal-fired power plant was applied to alfalfa meal-amended agricultural soil at levels equivalent to 0, 100, 400, and 700 tonne ha−1. Amended soils were placed in respirometer jars and monitored for C02-C evolution over a 37-day period. Fly ash applications of 400 and 700 tonne ha−1 reduced C02-C production significantly compared to 0 and 100 tonne ha−1 treatments. Carbon dioxide-carbon from all treatments was considerably greater than that from soil treated with 1000 ppm CdCl2. The results suggest that soil heterotrophic microbial activity may be impacted minimally by relatively low levels of fly ash application, but may be inhibited by higher levels of fly ash. Several metals were present at potentially toxic levels in the fly ash employed and may have accounted for the inhibition of CO2 C evolution. The availability of some of these metals was indicated in companion plant uptake experiments.
TL;DR: In this paper, a simple device is described to introduce powder as a pulse into an ICP (inductively coupled plasma), a tangential argon flow created inside the device (volume approx. 0.3 mL) mixes and carries the powder into the ICP.
Abstract: A simple device is described to introduce powder as a pulse into an ICP (inductively coupled plasma). A tangential argon flow created inside the device (volume approx. 0.3 mL) mixes and carries the powder into the ICP. A 2-kW forward power with 20 L min/sup -1/ coolant argon flow ICP is sufficient for excitation. (The reflected power is less than or equal to 5 W with or without the powder entering the autotuned plasma). Transient elemental emissions obtained from 0.5 to 2.5 mg of NBS Coal Fly Ash (1633a) are monitored by using a rapid scanning spectrometer. Detection limits for Cr, Sr, Tl, V, Cu, and Zn in the coal fly ash are in the nanogram level (1, 5, 7, 3, 2, and 2, respectively). Reproducibilities for these elements are less than or equal to 12% RSD. Acceptable recoveries for diluted coal fly ash indicate the potential for using NBS SRM's as standards for similar matrix samples. Elemental emissions have been observed from all powders attempted (silicon carbide, powdered whole blood, tomato vegetable dust, and granular chromatographic grade cellulose. 15 references, 7 figures, 3 tables.
Patent•
20 Mar 1984
TL;DR: In this article, the authors used a charge of clay mineral, feldspar, zeolite, coal ash, fly ash, pozzolan or volcanic ash for a time to develop fractures which increase the surface area of the particles.
Abstract: This invention is concerned with production and use of high surface area particulate matter by calcining a charge of clay mineral, feldspar, zeolite, coal ash, fly ash, pozzolan or volcanic ash for a time to develop fractures which increase the surface area of the particles. Vacuum calcining decreases the calcining time. The calcined matter desirably has an analysis including: calcium oxide, about 20-40 weight %; aluminum oxide, about 15-35 weight %; and silicon oxide, about 20-40 weight %. The calcined particulate matter can be used in the treatment of impure aqueous materials; the matter is denser than water and sludge settles rapidly and completely. The calcined matter interacts with heavy metal ions to form tightly bound sludge that is nonhazardous for landfill disposal. The calcined matter can be combined with conventual coagulants, flocculants, filter aids, or activated carbon to obtain a multipurpose treating agent. The calcined particulate matter can be combined with exotic waste water treating agents obtaining results not attainable by these exotic agents alone. The exotic agents are borohydride, dialkyldithiocarbamates where alkyl has 1-5 carbon atoms and `carbamate` has alkali metal or ammonium, dithionites, glycine, hydrazine salts, metabisulfites, polygalacturonic acid, water soluble sulfides and sulfites, and cellulose and starch xanthates.
TL;DR: In this paper, the authors describe the characteristics of the mineral matter in coal, show how the non-combustible material behaves at the high temperatures of boiler furnaces, explain how coal ash can lead to metal wastage by erosion and corrosion, and review problems in the collection of flyash attributable to coal ash composition.
TL;DR: In this paper, the microstructure and selected properties of the glasses and crystallized glasses were investigated using scanning and scanning transmission electron microscopy (SEM, STEM), Mossbauer spectroscopy, differential thermal analysis (DTA), and X-ray diffraction (XRD).
Abstract: Glasses synthesized from Illinois coal fly ash by conventional melt quenching were recrystallized by suitable nucleation and crystal growth heat treatments. The microstructure and selected properties of the glasses and crystallized glasses were investigated using scanning and scanning transmission electron microscopy (SEM, STEM), Mossbauer spectroscopy, differential thermal analysis (DTA) and X-ray diffraction (XRD). Crystallization of the fly ash glasses without the aid of added nucleating agents was possible up to a maximum of ∼23 vol %. The crystalline phase was tentatively identified on the basis of STEM microanalysis as a combination of ferroaugite [(Ca, Fe2+)(Al, Fe3+)2SiO6] and potassium melilite [KCaAlSi2O7]. Comparative results of the thermal expansion, density and microhardness of the glass and crystallized glass are reported along with the Young's modulus of a glass fibre pulled from the fly ash melt.
TL;DR: Spark source mass spectrometry is shown to be an excellent analytical tool for determining enrichment factors and a useful tool for measuring material balances for a coal-burning facility.
Abstract: Spark source mass spectrometry is shown to be an excellent analytical tool for determining enrichment factors and a useful tool for measuring material balances for a coal-burning facility. Measurements of enrichment and material balance are reported for 62 elements in two US coals obtained by using SSMS as the sole analytical technique. Copper was used as an internal reference. The halogens, Hg, S and Se were found to be lost to the stack. Systematic errors are noted in relative sensitivity coefficients for some of the elements, and between coal and ash samples.
01 Jan 1984
TL;DR: The standard leaching test developed by the SOSUV group (Working group for the development of standard leach procedures for coal ash and similar materials) is described in this paper, which aims at a close approximation of field conditions, so as to improve the prediction of possible environmental effects.
Abstract: The standard leaching test developed by the SOSUV group (Working group for the development of standard leaching procedures for coal ash and similar materials) is described. It is applicable to coal ash and ashes resulting from waste incineration. Unlike existing methods, the present test aims at a close approximation of field conditions, so as to improve the prediction of possible environmental effects. The test results permit the assessment of short-term ( 50 years) environmental impact. A numerical example is included for the leaching of powder coal fly ash. 7 figs., 3 tabs.
TL;DR: Blended cements prepared with two fly ashes were used as matrices in glass fiber reinforced cement (GRC) composites in an attempt to improve their durability as mentioned in this paper, however, the improved durability in one case was associated with modification in the microstructure of the hydration products deposited in between the glass filaments.
01 Mar 1984
TL;DR: In this article, the morphology, chemical composition and mineralogy of fly ash from a coal-fueled power plant have been investigated and a correlation between the crystalline and amorphous particles constituing the fly ash and the mineral matter present in the burnt fuel has been proposed.
Abstract: Morphology, chemical composition and mineralogy of fly ash from a coal-fueled power plant have been investigated. Optical and scanning electron microscopic examinations on both untreated particle samples and thin sections have enabled the investigation of internal and superficial microstructure. Chemical and diffractometric analyses performed on fly ash samples, fractionated by means of magnetic and gravimetric separators, associated the particle morphology to the elemental and mineralogical composition. A classification of single particles was achieved as follows: 1) glassy aluminosilicate with avariable composition; 2) spongy carbonaceous; 3) spherical metallic particles constituted of different iron oxide phases (magnetite, hematite, maghemite); 4) spherical rutile particles; 5) spherical lime particles; 6) mineral formless particles (i.e. quartz and mullite). The mineralogical composition of the coal utilized during instack samplings is also given. Lastly a correlation between the crystalline and amorphous particles constituing the fly ash and the mineral matter present in the burnt fuel has been proposed.
TL;DR: The escaping radioactivity from Greek coal power plants (CPP) was studied and the particulate dispersion of fly ash in sites around the stacks of CPP is described.
Abstract: The escaping radioactivity from Greek coal power plants (CPP) was studied. For the case studied the radioactivity is due to the uranium series. The major part (99%) escapes as very fine particles, while the rest is fly ash. The total escaping 226Ra activity is of the order of 40 Ci/yr. The particulate dispersion of fly ash in sites around the stacks of CPP is described. The hazards from the escaping radioactivity are evaluated.
Patent•
24 Oct 1984
TL;DR: In this paper, a method for the recovery of iron, aluminum and titanium from coal ash is described, which comprises magnetically extracting magnetite from the coal ash, leaching the ash with a solution of a mineral acid, precipitating and removing titanium and iron hydroxides from the leach solution by adding a strong base, and precipitated and removing aluminum hydroxide by contacting the remaining solution with carbon dioxide or aluminum hyroxide seeding.
Abstract: A method is disclosed for the recovery of iron, aluminum and titanium from coal ash. The method comprises magnetically extracting magnetite from the ash, leaching the ash with a solution of a mineral acid, precipitating and removing titanium and iron hydroxides from the leach solution by adding thereto a solution of a strong base, and precipitating and removing aluminum hydroxide by contacting the remaining solution with carbon dioxide or aluminum hydroxide seeding.
Journal Article•
TL;DR: Etude preliminaire sur la fabrication de ciments melanges a partir de ciment Portland, de poussieres de four a ciment, de cendres volantes et de scorie as discussed by the authors.
Abstract: Etude preliminaire sur la fabrication de ciments melanges a partir de ciment Portland, de poussieres de four a ciment, de cendres volantes et de scorie. Etude de la resistance a la compression, de la prise et de l'ouvrabilite des ciments obtenus
TL;DR: In this article, the use of X-ray emission spectroscopy for the study of fly-ash particles is reported where different techniques of sample excitation were used. And the elemental composition of bulk ash was obtained by exposing the samples to radiation from radioactive sources, Xray tube and synchrotron radiation.