02267 Multivariable analysis on the distribution of potentially hazardous elements in coal and its geochemical significance

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Solid fuels (sources, winning, properties)

oxidation, are also present in the three bituminous coal samples. This information is essential in developing predicttve models for arsenic behaviour during coal combustion and in other environmental settings. Mode of occurrence of chromium in four US coals 00102266 Huggins, F. E. Furl Processing Technology, 2000, 63. (2-3). 79992. The mode of occurrence of chromium in three US bituminous coals and one US sub-bituminous coal has been examined using both X-ray absorption fine structure (XAFS) spectroscopy and a selective leaching protocol supplemented by scanning electron microscopy (SEM) and electron microprobe measurements. A synthesis of results from both methods indicates that chromium occurs principally in two forms in the bituminous coals: the major occurrence of chromium is associated with the macerals and is not readily leached by any reagent, whereas a second, lesser occurrence, which is leachable in hydrofluoric acid (HF), is associated with the clay mineral, illite. The former occurrence is believed to be a small particle oxyhydroxide phase (CrO(OH)). One coal also contained a small fraction (< 5%) of the chromium in the form of a chromian magnetite and the leaching protocol indicated the possibility of a similar small fraction of chromium in sulfide form in all three coals, There was little agreement between the two techniques on the mode of occurrence of chromium in the sub-bituminous coal; however, only a limited number of sub-bituminous coals have been analysed by either technique. The chromium in all four coals was trivalent as no evidence was found for the Crb+ oxidation state in any coal. Multivariable analysis on the distribution of 00102267 potentially hazardous elements in coal and its geochemical significance Feng, X. er al. Kucrngiru Xuehao, 1999, 19, (I), 3440. (In Chinese) Having completed the study into the distribution behaviour of sulfur, iron, arsenic, cadmium, mercury, lead, selenium, antimony, thallium and zinc in coal seams of the Longtan Group of the Permian Period in Guizhou Province, multivariable analysis was used in the study of correlations among these elements in the coal seams from the correlations among these elements and the elemental geochemistry. Of these elements, useful information was obtained about the possible modes of occurrence of these elements in coal seams of the Longtan Group in Guizhou. (1) Arsenic, mercury and antimony may exist in late-stage pyrite in coal; (2) zinc and selenium in sphalerite; (3) lead in galena; (4) according to the elemental goechemistry of cadmium, it may exist in sphalerite, however, cadmium contents in coal are too low to get exact analysis results, and the correlation between zinc and cadmium was erased; (5) the modes of occurrence of thallium in coal are complex. When this method was applied to the study of the modes of occurrence of trace elements in coal, a set of representative samples should be obtained and in addition the accurately analysis results of the trace elements in coal should be acquired. 00/02268 New concept for the calculation of the trace element affinity in coal Klika, Z. and Kolomaznik, Z. Fuel, 2000, 79, (6) 659-670. The present models for the calculation of the trace element affinity between organic and inorganic parts of coal are critically evaluated and a new concept of calculation is proposed. This new concept of calculation is based on the experimental data characterizing coal fractions separated from coal samples using sink-float technique. It consists in the calculation of (a) organic element association (OEA) supposing constant concentration of the element in organic phase and (b) maximal organic element association (OEA,,,) supposing maximal possible concentration of the element in the organic phase of all coal fractions. For one coal sample OEA and OEA,,, are calculated. It must be valid that OEA < OEA,,,. This relation is not true for some elements, e.g. Ge and Ga, which usually have extremely high concentration in the lightest coal fraction. Contemporary with OEA the inorganic element association (IEA) is evaluated. Using least squares method the IEA can be recalculated among mineral groups present in coal. The model was successfully tested on one sample of bituminous coal and one sample of brown coal. 00102269 Partitioning of arsenic, selenium and cadmium during the combustion of Pittsburgh and Illinois #6 coals in a selfsustained combustor Seames, W. S. Fuel Processing Technology, 2000, 63, (2-3), 179-196 An important environmental issue is the emission of semi-volatile toxic metals, such as arsenic, selenium and cadmium, from the combustion of coal. These materials may vaporize in the hot portions of the combustor then return to the solid phase in cooler zones of the process downstream. Understanding the mechanisms by which toxic metals partition between the vapour and solid phases is an important step for predicting and mitigating the effect of these metals upon the environment. Particulate ash samples were withdrawn from a 17-kW pilot-scale downflow combustor in which pulverized coal was burned under self-sustaining conditions. The samples were size segregated in a Berner low pressure impactor and then analysed using neutron activation. This research approach has suggested mechanisms, which govern the partitioning of arsenic, selenium and cadmium in practical pulverized coal combustion processes. The results suggest that volatilization and subsequent transfer of selenium to submicron particle surfaces appears to be an important post-combustion phase mechanism for Illinois No. 6 coal but not for Pittsburgh seam coal. Most of the selenium in the Pittsburgh submicron fly ash, cadmium in Illinois No. 6 submicron fly

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ash and arsenic in both Pittsburgh and Illmois No. 6 submicron fly ash enters the post-combustion zone in the solid phase. The dominant heterogeneous partitioning mechanism for transformation to large, supermicron particles is the reaction of metal vapour on the surface or within the pores of an ash particle. The results also suggest that the rate of transformation is dominated either by an exterior surface reactioncontrolled regime or a pore diffusion-controlled regime. A relationship between the concentration of solid phase arsenic, selenium and cadmium to calcium in supermicron particles was also observed, suggesting the formation of arsenic-calcium, selenium-calcium and cadmium-calcium reaction products. 00/02270 Posidonia horizons and their role in correlation of the carboniferous coal-bearing formations of the Lvov-Volyn and Lublin basins Shylga, V. F. PI ul. GrolZh., 1998, l-2, 141-147. Three successive Posidonia horizons occur in the lower part of the Buzhanska Formation which composes the basal part of the Upper coalbearing sub-formation in the Lvov-Volyn Basin. They contain marine and lagoonal argillites and yield bedded accumulations of bivalves and ammonoids. An analysis of the Posidonia horizons is important for correlations of the coal-bearing formation in the Lvov-Volyn and Lublin basins and for their global correlation. 00102271 Provisions for safe operations at outburst-prone coal layers Zorin, A. N. and Kolesnikov, V. G. Bezop. Tr. Promsfi., 1998, II, 52-53. (In Russian) This is a review of the monograph by V.I. Nikolin and M.P. Vasiltshuk entitled, ‘Prognostics and prevention of outbursts in coal mining’. 00/02272 Quality and petrographic characteristics of the lacustrine Ermenek coal (Early Miocene), Turkey Demirel, I. H. and Karayigit, A. I. Energy Sources, 1999, 21, (4), 329-338. The Early Miocene Yenimahalle Formation, including alluvial-lacustrine sediments and a mineable coal seam with an average of 5 m in thickness, rests unconformably upon the basement and is also unconformably overlain by marine limestones of the Middle-Late Miocene Mut Formation in the Ermenek coal basin. The coal basin in the present study has been subdivided into two areas, Canakci and Pamuklu-Tepebasi, which are separated by the basement and a fault, in order to determine coal properties in detail. The investigated sub-bituminous coals with an average of 0.40% Ro huminite reflectance often contain gastropod shells (Planorbidae) which commonly maintain the original aragonite and calcite composition. The coals have similar chemical properties and petrographical composition in the two areas, but their sulfur contents are clearly different. In the Canakci area the coals on an air-dried basis contain distinctly less total sulfur and organic sulfur contents than in the Pamuklu-Tepebasi area. This difference is interpreted to be controlled by mire chemistry and sedimentation during peat formation. Research on coal reactivity: making a comparison 00102273 between hydrogenation with H-donor solvent and thermogravimetry in N2 atmosphere Feng, J. er al. Proc.-Annu. Inr. Pitrshurgh Coal Co$.. 1998, 15, 1356-1363. A study was made on seven kinds of coals, from ltgnite to anthracite. The activation energy was calculated from thermogravimetry and it was found that the amount of hydrogen transferred during coal reaction with the Hdonor Tetralin was comparable. The methodology of canonical relation analysis was used to compare the two kinds of reactivities. 00102274 Structure properties, and reactivity of solid fuels Hurt, R. H. Symp. (hr.) Comhusr., [Proc.J, 1998, 2, 2887-2904. Approaching the third millennium, solid fuel combustion, one of man’s oldest technologies, continues to play an important societal role. Various economic and environmental factors are leading to a diversification .in fuels-the practitioner can no longer restrict his or her interest to the combustion behaviour of one or several regional coals but must consider a wide variety of potential solid fuels, including biomass, solid wastes, and internationally traded coals. This paper begins with a brief discussion of the technology issues that define research needs in solid fuel combustion and then presents a brief overview of the fuels themselves and their important fundamental properties. A central theme in the paper is the remarkable variation in the structure, reactivity, and properties of chars from the diverse array of practical solid fuels. The density, oxidation reactivity, and physical adsorption capacity are identified as key char properties, as they strongly influence the degree of carbon burnout in pulverized fuel combustion, the volume of the solid waste produced, and the behaviour of the resulting fly ash in post-combustion utilization schemes, most notably concrete. Many char properties are shown to depend on char crystalline structure, or nanostructure, which varies from disordered to ordered as a function of precursor chemical and char formation conditions. Another theme in the paper is the possibility of predicting combustion rates and burnout times of different solid fuels in a common combustion environment. The paper discusses predictive schemes, which are based on hybrid correlative and mechanistic approaches, in which intraparticle and boundary-layer transport processes are described mechanistically, while surface reactivity and particle density are obtained from empirical correlations with parent fuel properties. Although these complex solids