Showing papers on "Fly ash published in 1975"

Pathways of thirty-seven trace elements through coal-fired power plant

Abstract: Coal, fly ash, slag, and combustion gases from a large cyclone-fed power plant 870 MW(e) were analyzed for a suite of elements. Mass balance calculations show that the sampling and analyses were generally adequate to describe the flows of these elements through the plant. Most Hg, some Se, and probably most Cl and Br were discharged to the atmosphere as gases. As, Cd, Cu, Ga, Mo, Pb, Sb, Se, and Zn were quite concentrated in fly ash compared to the slag, and were more concentrated in the ash discharged through the stack than in that collected by the precipitator. Al, Ba, Ca, Ce, Co, Eu, Fe, Hf, K, La, Mg, Mn, Rb, Sc, Si, Sm, Sr, Ta, Th, and Ti show little preferential partitioning between the slag and the collected or discharged fly ash. Cr, Sc, Na, Ni, U, and V exhibit behavior intermediate between the latter two groups. (auth)

Elemental concentrations in the National Bureau of Standards' environmental coal and fly ash Standard Reference Materials

Abstract: The four participating laboratories measured the concentrations of 37 elements in NBS standard coal (SRM 1632) and 41 in fly ash (SRM 1633). Most of the measurements were done by instrumental neutron activation analysis, which was done by each of the laboratories. In addition, one laboratory used instrumental photon activation analysis and another counted the natural radioactivity to determine concentrations of K, Th, and U. The results obtained are in good agreement with the values given by NBS for the twelve elements in each material for which both they and we have values. For most elements for which comparisons can be made, the interlaboratory dispersion of results obtained in this work is much less than was obtained in a recent roundrobin analysis of these materials by many laboratories using a variety of techniques. Average concentrations for the 37 elements in the coal standard and 41 elements in the fly ash standard are presented for comparison with results that may be obtained by other laboratories.

Long-Term Exposure to Sulfur Dioxide, Sulfuric Acid Mist, Fly Ash, and Their Mixtures

Abstract: Groups of cynomolgus monkeys and guinea pigs were exposed to mixtures of sulfur dioxide, fly ash, and sulfuric acid mist. The exposure concentrations varied between 0.1 and 5.0 ppm for sulfur dioxide, 0.1 and 1 mg/cu m for sulfuric acid mist, while a concentration of approximately 0.5 mg/cu m was used for fly ash. The duration of exposure was 52 weeks for guinea-pigs and 78 weeks for monkeys. Pulmonary function tests and serum biochemical and hematological analyses were conducted prior to and periodically during the exposure period. At the termination of exposure, the lungs were examined microscopically. Analysis of the data revealed that in groups exposed to the mixtures of pollutants, sulfuric acid mist was responsible for the effects observed. No synergistic action between the pollutants was detected.

An Empirical Study of the Relation of Chemical Properties to Ash Fusion Temperatures

Abstract: Regression analysis is used to develop equations for calculating fusion temperatures of coal ash from chemical composition, based on 1250 analyses of ash from both eastern and western US coal. Standard errors for the equations are generally less than 27/sup 0/C, which is the analytical tolerance of the ash fusion temperature measurements. Equations are given for eastern, western and combined eastern and western coals. These equations: (1) provide a technique for calculating ash fusion temperatures from the chemical composition of the ash; (2) provide a method for calculating the ash fusion properties of coal blends; and (3) provide an improved understanding of the effect, significance and interactions of ash elements with respect to the thermal properties of coal ash.

New and Conventional Engineering Uses of Fly Ash

Abstract: Successful uses of pozzolanic fly ash for modification of a highly plastic clay, and of natural and stabilized fly ashes to effect economy in road construction, are described. Three fly ashes collected in dry, moist, and sludge states were investigated in detail for modification of a highly plastic clay. Laboratory investigations were conducted to determine suitability of natural fly ash for structural fill, and lime and cement stabilized fly ashes for base course construction. Field trial sections were constructed and performance tests made to evaluate technical and economic feasibility. Laboratory and performance data on trial sections indicate that: (1) It is possible to modify a highly plastic clay with a pozzolanic fly ash to provide stable subgrades; (2) structural fills of compacted pozzolanic fly ashes gain strength with time and are lighter and stronger than clay or sand fills; and (3) base courses of cement stabilized fly ashes can be constructed with available equipment.

Trace element discharges from coal combustion for power production

Abstract: Partition factors have been calculated to describe the distribution of 38 elements between slag, total fly ash, atmospherically emitted fly ash, and vapors for a coal fired steamplant. These factors have been generalized to other types of boilers, to calculate the annual U.S. discharge of trace elements due to coal combustion for power production. The magnitude of trace element mobilization by coal combustion is compared with industrial consumption of trace elements, and with estimates of their natural mobilization by weathering. Elemental flows due to coal consumption are never less than 1.5% of their weathering mobilization, and coal combustion introduces As, Co, Cu, Fe, Hg, Mo, Ni, Pb, Sc, Se, U, V, and Zn into the environment at rates comparable to their rates of introduction by weathering.

Effect of soil application of fly ash on chemical composition and yield of corn ( Zea mays L.) and on chemical composition of displaced soil solutions

Abstract: Field investigations were initiated in 1971 to study the effect of a weathered fly ash sample on yield and nutrient concentration of corn (Zea mays L.) and on composition of displaced soil solutions, and to determine rates of fly ash that could be applied to soils without adversely affecting plant growth. Application of weathered ash at rates ranging from 18 to 288 metric tons/ha did not decrease corn grain yields on either Groseclose silt loam or Woods-town loamy fine sand. Corn grain yields were increased on the Woodstown soil in 1972 where cumulative rates of 216 and 288 metric tons/ha of fly ash were applied, which was attributed in part to increased soil moisture. Plant analysis data indicated that B and Mn concentrations were not increased to toxic levels as had been reported in other investigations with unweathered fly ash. Soil solution data verified that toxic amounts of these elements were not released from the weathered ash sample.

Surface Resistivity and the Chemical Composition of Fly Ash

Abstract: Resistivity was determined for a group of well characterized ashes representing both eastern and western coals. Data were taken between 60 and 250°C in an environment of air containing approximately 9 volume percent water. Chemical transference experiments were conducted for two ashes having substantially different chemical compositions. Chemical analyses of the transference specimens revealed a pronounced migration of alkali metal ions toward the negative electrode. It was observed that the surface resistivity was inversely proportional to the concentration of these ions and that the iron concentration influenced particularly the participation of potassium. Surface resistivity is sensitive to the chemical composition of fly ash because the alkali metals serve as charge carriers. The conduction mechanism is probably analogous to that of glass. This viewpoint is compatible with the usual empirical observations regarding the effect of certain parameters on resistivity; for example, the interaction between a...

Pozzolans - a review

Abstract: The occurrence, availability, and use of natural pozzolans and fly ash, their effects on the properties of concrete and the state of our knowledge regarding their chemical and physical action are discussed. The need for research on high-lime fly ashes and for extending the use of fly ash in cement blends is proposed.

Mass balance of trace elements in Walker branch watershed: relation to coal-fired steam plants.

Abstract: A mass balance study of trace element flows at the TVA Allen Steam Plant at Memphis showed that most of the released Hg, some Se, and probably most Cl and Br are discharged to the atmosphere as gases. The elements As, Cd, Cu, Ga, Mo, Pb, Sb, Se, and Zn were concentrated in fly ash compared to slag and were more concentrated in the ash discharged through the stack than in that collected by the precipitator, while Al, Ba, Ca, Ce, Co, Eu, Fe, Hf, K, La, Mg, Mn, Rb, Sm, Sr, Ta, Th, and Ti showed little preferential partitioning between the slag and the collected or discharged fly ash. The elements Cr, Cs, Na, Ni, U, and V exhibited behavior intermediate between the latter two groups. This information about stack emissions of trace elements from the Allen Plant was used to estimate the likely range of air concentrations and input (dry and wet deposition) to the Walker Branch Watershed. The watershed, which is on the ERDA reservation at Oak Ridge, is within 20 km of three coal-fired steam plants, two in the TVA system and one belonging to ERDA. The estimated input values are compared to measurements of Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn in wet precipitation falling on the watershed during 1973 and 1974. Dry deposition of these elements could not be measured directly but estimates indicated that this could be of the same order of magnitude as the rainwater input. A six-month mass balance indicated that the watershed efficiently retains Pb (97-98% of the atmospheric input,) Cu (82-84%), while Cr (69%), Mn (57%), Zn (73%), and Hg (69%) are less well retained.

Multielement Residues in Tissues Clover Grown on Fly Ash of Guinea Pigs Fed Sweet

Abstract: Yellow sweet clover (Meliloius officinalis) was harvested from fly ash dlumped in a landfill site at Lansing, NY. This clover was chopped, dried, and formulated at 45% into an otherwise purified diet and fed to six guinea pigs for 90 days. Control sweet clover was harvested from gravelly subsoil and processed and fed to another group of guinea pigs for the same period Samples of fly ash, gravelly subsoil sweet clover, liver, kidneys, and left-rear gastrocnemius muscle of all guinea pigs were freeze-dried and analyzed tor 35 elements by neutron activation analysis. The fly ash contained 28 elements at higher levels than the gravelly subsoil, while the clover harvested from fly ash contained 19 elements in increased amounts over those in the clover harvested from the gravel soil. Growth rate of both groups of guinea pigs was similar. Rubidium and selenium were present at higher levels in the tissues of guinea pigs fed the fly ash clover.

Effects of the discharge of thermal effluent from a power station on Lake Wabamun, Alberta, Canada — Limnological features

Abstract: The physical and chemical aspects of Lake Wabamum have been described. Modifications to the thermal and dissolved oxygen regimes through the discharge of thermal effluent into the eastern region of the lake are discussed. This discharge has, therefore, changed the environmental conditions under which the biota exists in the eastern portion of the lake. It was also shown that this discharge of heated water had no effect upon the water chemistry while the power station itself contributed silica, in the form of fly ash, to the system. Tables of the phytoplankton, zooplankton, aquatic macrophytes, and fish are provided. From a biological and limnological stand point the lake can be classified as a moderately eutrophic lake, especially in the eastern portion.

Conditioning of fly ash with ammonia

Abstract: This paper presents the results of an investigation of the conditioning of fly ash with ammonia in electrostatic pre-cipitators of power plants operated by the Tennessee Valley Authority. It focuses attention primarily on the mechanisms of conditioning encountered under the particular circumstances available for study. No effect of ammonia on the electrical resistivity of fly ash was evident. Instead, the effect of ammonia appeared to be an enhancement pf the space-charge component of the electric field used for charging and precipitating particles of fly ash. In addition, a second effect appeared to be an increase in the cohesiveness of precipitated ash and a reduction in the quantity of ash reentrained during electrode rapping. Data demonstrating the value of ammonia conditioning for lowering the emission pf fly ash during three precipitator studies are presented. Reasons for the ineffectiveness of ammonia conditioning during a fourth precipitator study are discussed. In conclusion, comments are made ab...

Method of removing fly ash particulates from flue gases in a closed-loop wet scrubbing system

Abstract: A method of removing fly ash particulates suspended in industrial waste gases generated from the combustion of fossil fuels in a totally enclosed scrubbing liquor circuit whereby an inert diluent such as Na2 SO4 is used for inhibiting the dissolution rates of the alkaline earth, silica, and clay mineral ingredients in the ash when the collected particulates are intermixed and suspended in weak acid solutions produced in the wet scrubbing process. The diluent may be added to the system or, if the waste gas contains significant amounts of sulfur oxides, it may be formed in situ.

Controlled density fill material containing fly ash

Abstract: The invention relates to a controlled density fill material and a method of using such fill material in, for examples, the backfilling of sewers, embankments, structures and utility trenches. The material includes Portland cement, fly ash and aggregates. The material, while having some properties of both, is neither a soil nor a concrete.

Densification of coal fly ash

Abstract: Densified fly ash pellets are produced by the steps comprising: A. Sizing the fly ash to produce a fraction substantially finer than -200 mesh (U.S. Standard); B. Moistening the sized fraction with sufficient water to form green pellets; C. Sizing the green pellets; D. Tumbling the sized green pellets to effect particle packing until excess water has been squeezed out, said pellets being kept dusted during tumbling with sized fly ash from step (a) to absorb the squeezed out water and thereby prevent agglomeration; E. Drying the packed green pellets to remove the free water therefrom; F. Heating the dried pellets from about 1000° F to within about 70 - 90% of the absolute softening temperature of the ash and; G. Sintering the pellets from (f) at a temperature of 70 to 90% of the absolute softening temperature of the ash. The densified fly ash pellets constitute a low cost particulate heat exchange material for supplying heat to a fluidized bed carbon gasification zone.

Lead contents of coal, coal ash and fly ash

Abstract: Flameless atomic absorption spectrometry is applied for the determination of Pb in coal, coal ash and fly ash. Lead concentrations in coal and coal ash ranging from respectively 7 to 110 µg g−1 and 120 to 450 µg g−1 are found. A mean concentration of 1520 µg g−1 in fly ash corresponding to a concentration of 117 µg m−3 in the effluent gas suggests the importance of coal combustion as an atmospheric source of Ph. The contribution of coal combustion to the total Pb emissions is conservatively estimated at 6%.

Multielement residues in tissues of guinea pigs fed sweet clover grown on fly ash.

Abstract: Yellow sweet clover (Melilotus officinalis) was harvested from fly ash dumped in a landfill site at Lansing, NY. This clover was chopped, dried, and formulated at 45% into an otherwise purified diet and fed to six guinea pigs for 90 days. Control sweet clover was harvested from gravelly subsoil and processed and fed to another group of guinea pigs for the same period. Samples of fly ash, gravelly subsoil, sweet clover, liver, kidneys, and left-rear gastrocnemius muscle of all guinea pigs were freeze-dried and analyzed for 35 elements by neutron activation analysis. The fly ash contained 28 elements at higher levels than the gravelly subsoil, while the clover harvested from fly ash contained 19 elements in increased amounts over those in the clover harvested from the gravel soil. Growth rate of both groups of guinea pigs was similar. Rubidium and selenium were present at higher levels in the tissues of guinea pigs fed the fly ash clover.

Lime-fly ash-aggregate-sludge paving material

Abstract: A composition and method for producing an improved lime-fly ash-aggregate is disclosed. The composition is prepared by mixing together lime, flyash, graded aggregate, adding water, and from 0.5 to 4 percent, based on total dry weight, of sludge from a water treatment plant. The mixture is placed on top of a prepared subgrade, spread uniformly, and compacted to a high degree of relative density to provide the main load-carrying component of a road, airport runway, parking lot or the like.

Converting power station wastes into usable materials - fly ash and calcium sulphate mixed to form construction materials

Abstract: Fly ash and other residues obtd. from the flue gas of powder stations, esp. from coal-burning power stations are converted to useful matls. by feeding the dust and ash from the dry separator to a mixer together with the dried and/or calcined residues obtd. from the scrubbing plant used to remove sulphur dioxide from the flue gas; the two materials are fed to the mixer in suitable proportions so that a stone- or brick- granulate is obtd. which can be milled in accordance with the planned end use. In addn. to producing a usable constructional material, the process solves a major disposal problem. The matl. is used as ballast for roads or embankments or aggregates for tarred surfaces or for concrete; by suitable addns. it can be made into a cement type of binder.

Apparatus for the manufacture of light granulates

Abstract: An expanded granular material, particularly intended as a lightweight aggregate for concrete, is produced by melting a finely ground fusible silico-aluminous material, such as fly ash, in the presence of a controlled atmosphere intended to inhibit the liberation of gases coming from the silico-aluminous material, and then forming the melt into drops and cooling under conditions to permit gases to escape from the material thereby causing is expansion.