04 By-products related to fuels

resolve the influence of the aggregate properties. The strength of the concrete could not be accounted for by the strength of the aggregates only. and it is suggested that the absorption and pozzolanic activity of the aggregates could influence the strength developed.

97103702 The effect of particle volume fraction on the mechanical properties of aluminum-fly ash MMC Liu, X. and Nilmani, M. Process. Prep. Appl. Cast Met. Matrix Compos. Proc. Symp., 1996, 297-305. Edited by Rohatgi. P. K. Minerals, Metals & Materials Society, Warrendale, PA. A low-cost full liquid route was used to produce aluminium-fly ash metal matrix composite (fly ash MMC) of A380 alloy. The tensile strength and hardness properties of up to 20% (volume) fly ash particles (microspheres) MMC were measured. An image processing technique determined the volume fraction and the distribution of fly ash microspheres. Both the tensile strength and the hardness of the fly ash MMC decrease with increasing microsphere volume fraction, which is likely due to the presence of porosity and debonding. The microstructure of the fracture surface of the tensile test specimens suggests that debonding between the microspheres and aluminium matrix is the main reason for this lowering of the mechanical properties. However, strength to weight ratio of the fly ash MMC is similar or marginally better than the pure alloy. The fly ash MMC density was 15% to 20% lower than the matrix alloy.

97103783 Extracting useful elements from fine coal ash. XU, K. et al. Huanjing Gongcheng, 1995, 13, (5), 52-55. (In Chinese) Iron and carbon extraction from fine coal ash is studied in detail and the paper suggests future ways of using fine coal ash.

97103784 Factors influencing flow and strength of standard mortars and reappraisal of ASTM test methods for fly ash Helmuth, R. Cem. Concr. Aggregates, 1996, 18, (2). 98-111. Tests for fly ash or natural pozzolans sampling and testing for use as a mineral admixture in Portland-cement concrete were modified (ASTM C 311). Pozzolanic (Strength) Activity Index tests with five fly ashes and two portland cements were done to compare results with those of standard tests. With varying sand contents strengths of 38°C cured mortars decreased for different cement/fly ash blends. When water contents were varied, strengths varied, tending to increase because of paste volume increases with water content. Flow of mortars in both kinds of tests increase nearly linearly with paste volume fractions. Accelerated curing at 38°C for tests at 28 days usually yields higher relative strengths than after curing at 23°C for 91 days. Multiple linear regression equations using both kinds of test data were solved at specified flow and strength values to determine proportions and mortar volume yields. This more general performance test ranks fly ashes by mortar volume yield at equal flow and strength, and is proposed as a replacement to the present Strength Activity Index test.

97103785 FGD by-product production at Petersburg Station Wolsiffer, S. and Wedig, C. FGD Synth. Gypsum, Int. Conf, [Proc.], 5rh, 1997, 911-10. Edited by Luckevich, L. M. et al., ORTECH. Mississauga, Ontario. Since the late 197Os, lndianapolis Power & Light Company (IPL) has operated limestone-based SOZ removal systems at the Petersburg Generat- ing Station. The four-unit coal-fired station is the base load generation capacity for the IPL electricity system. The boilers are all equipped with flue gas desulfurization (FGD) equipment. Various FGD vendors and process designs are used, and the plant produces both sulfite and gypsum by-product materials. The various FGD by-products are both landfilled on site and sold for the manufacture of wallboard. Operating experience relative to the different FGD system designs and by-product production unique to this site-specific situation are presented.

97103786 Fixation of radioactive cesium by utilizing fly ash Korea Institute of Atomic Energy Jpn. Kokai Tokkyo Koho JP 09,132,408 [97,132,4081 (Cl. COlB33/00), 20 May 1997, KR Appl. 9,539,590, 3 Nov 1995, 3 pp. (In Japanese) Compounds of gas-phase caesium were reacted with porous collecting material made from coal ash, at 700-1300°C to fix radioactive cesium in a form of cesium aluminosilicate.

97103787 Fly ash in concrete Xu, A. Waste Mater. Clsed Concr. Manuf., 1997, 142-183. Edited by Chandra, S. Noyes, Westwood, N. J. Mechanisms and behaviour of fly ashes in concrete form the basis of this paper. Characterization of fly ash and hypotheses on hydration mechanisms for cement systems containing fly ash are discussed.

97103788 Growth of forages on acid soil amended with flue gas desulfurization byproducts Clark, R. B. et al. Fuel, 1997, 76, (8). 771-775. Experiments were carried out to assess beneficial or detrimental plant growth effects when flue gas desulfurization by-products (FGD-BPS) are applied to acid soil. Tests were conducted in a greenhouse to determine growth of forages on an acid pH 4.6 soil with different levels of three FGD- BPS and chemical-grade calcium carbonate, calcium sulfate and calcium sulfite. The FGD-BPS tested were high-CaSO,,, high-CaSOd enriched with Mg, and high-CaSOs. Use of -2.5% of high-CaS04 FGD-BP + Mg

incorporated into soil mixes yielded the maximum total plant dry matter (DM). DM decreased at higher levels of addition. The results are presented in detail. The FGD-BPS used in this study benefited forage growth when added at appropriate levels.

97103789 High early strength concrete hardened bodies containing fine fly ash Tashiro, C. Jpn. Kokai Tokkyo Koho JP 09.118,556 [97,118.556] (Cl. CO4828/02), 6 May 1997, Appl. 951301,994, 25 Ott 1995. 3 pp. (In Japanese) The concrete hardened bodies contain finely crushed fly ashes with specific surface area by blaine <4000 cm’ig. The concretes are especially suitable for pavements and concrete products.

97103790 Hydration and weathering reactions in by-products from clean coal technologies: effects on material properties Weinberg, Andrew and Hemmings, R. Fuel, 1997, 76, (8). 705-709. AFBC by-products and Class F coal fly ash were used to construct three landfill test cells at a site in central Illinois. They were monitored over a S year period as part of a DOE METC effort to characterize by-products from clean coal technologies. The field program documented rapid loss of structural integrity in cell 1, which contained no fly ash, whereas cells 2 and 3. constructed with an FBC-fly ash mix, showed improved strength and permeahility over time. These differences are related to loss of soluble minerals from cell I and enhanced silicate reactivity in cells 2 and 3. Ettringite and thaumasite, minerals associated with failure of Portland cement concrete, do not appear to be the primary causes of cell 1 deterioration. Ettringite remained a primary cement-forming mineral in cells 2 and 3, but increased availability of reactive silica led to formation of calcium silicate hydrate rather than thaumasite, increasing long-term durability.

97103791 Hydration process of cement containing fly ash and silica fume: the first 24 hours Lilkov, V. et al. Cem. Concr. Res., 1997. 27, (4), S77-S88. The early hydration (up to the 24th hour) of cements mixed with fly ash, silica fume or a combination of both, called Pozzolit. was investigated. The active role of the Pozzolit mineral additive was revealed by DTA. XRD and IRS analyses. The effect of the additive is expressed in increased total amount of hydration products and decreased portlandite content.

97103792 Immobilized microorganism for improvement of crop production Nagashima, K. and Uzawa, T. Jpn. Kokai Tokkyo Koho JP OY.l65,312 [97,165,312] (Cl. AOlN63100). 24 Jun 1997, Appl. 95/32Y,294. IX Dee IYYS. 8 pp. (In Japanese) In the presence of coal ash, the immobilized micro-organism has excellent shelf life and promotes the crop production.

97103793 Impact of fly ash incorporation in soil on germina- tion of crops Kalra, N. et al. Bioresource Technology, 1997, 61, (1). 39-41. In order to evaluate the effect of ash incorporation in soil on germination and stand establishment of various crops, pot-culture experiments were conducted. Ash levels tested were 0, lo%, 20%, 30% and 40% for winter- season crops, and 0, S%, lo%, 15% and 20% for summer-season crops. Changes in soil physical and chemical characteristics due to ash addition were analysed. Germination time and delay index were introduced to evaluate ash-incorporation effects on crop germination. Ash addition was found to delay crop germination due to the increased impedance offered to germinating seeds by the soil matrix. The delay index showed variations between crops as well as for ash levels within a crop.

97103794 Infiltration processing and mechanical properties of metal-fly ash composites Robatgi, P. K. er al. Process. Prep. Appl. Cost Met. Matrix Compos. Proc. Symp., 1996, 103-117. Edited by Rohatgi, P. K. Minerals, Metals & Materials Society. Warrendale, PA. Loosely packed beds of cenosphere fly ash (above 55 ~01% in the composite) were successfully infiltrated by molten aluminium under pressure in the range 0.3-0.7 MPa. The density of infiltrated aluminium- fly ash composite (1.4 g/cm’) is roughly half of that of aluminium (2.68 gi cm’). This makes it a very attractive low density, low cost material for automotive applications. The density, hardness, and compressive strength vary along the length of the composite with the position in the composite. The portion with high-density exhibits higher hardness and compressive strength.

97103795 Influence of the calcium content on the coal fly ash features in some innovative applications Catalfamo, P. et al. Resouces, Conservation and recycling, 20, (2), 119-125. Recent trends in the innovative uses of coal fly ash based on its chemical properties have been successful, in spite of its low chemical reactivity. Lots of fly ash showing sharply alkaline reaction are usually high-calcium. These are suitable to be used as remotion agents of heavy metals in wastewater or retentive agents in polluted solids. Those producing substantially neutral reactions are usually low-calcium, suitable for conversion by hydrothermal treatments into zeolitic products, where higher calcium contents interfere.

318 Fuel and Energy Abstracts September 1997