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The trace elements (As, B, Ba, Be, Bi, Cd, Co, Cr, Cs, Cu, Ga, Ge, Hg, Li, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sn, Sr, Ta, Th, Tl, U, V, W, Y, Zn, Zr and REE) in a subbituminous coal and their behaviour during combustion in a large power station were characterized by their content and distribution in the fuel (organic and/or inorganic affinities) and in the combustion wastes (partition and volatility). Samples...
The elemental compositions of framboidal pyrite and associated maceral types of a Devonian oil shale were investigated using a micro-analysis particle-induced X-ray emission (PIXE) technique. The majority of the PIXE analyses were performed using a 750 keV proton beam to investigate sulfur and iron concentrations. Trace metals in the framboids and associated macerals were analysed using a proton...
Factor analysis and cluster analysis were applied to the distribution characteristics of ten trace elements in seven Chinese coals. The factor analysis showed that a three-factor model interprets reasonably the correlations of these trace elements. The results of Q- and R-cluster analysis showed that the seven samples and ten trace elements clustered reasonably into different groups. The results...
The fate of trace element pollutants in integrated gasification combined-cycle (IGCC) systems is closely tied to their volatilization in the gasifier and subsequent condensation or reaction with fine fly ash particles. The results of an experimental bench-scale programme to measure the partitioning of selected trace elements during atmospheric pressure entrained flow gasification of Illinois No.6...
Coal in the Eastern Kentucky coalfield has been, and continues to be, a valuable energy resource, especially for the electric utility industry. However, Federal mandates in Titles III and IV of the Clean Air Act Amendments of 1990 have placed increasingly stringent demands on the type and grade of coal that can be burnt in an environmentally acceptable manner. Therefore, a greater understanding of...
This study reports on the elemental concentrations and vertical variation of coal seams from the Obed Mountain deposit, Alberta Foothills, Canada. Results from two sections of Seam 1 show that the major elements (i.e. Al, Fe, Mg, K, Na, Ti, and Si) have high concentrations in intervals having high ash content, with the only exception of Ca. Similarities are apparent, in both sections, in the vertical...
The present work consists of verifying a theoretical model based on mass distribution of trace elements in coal. Many versions of the model were tested using 42 elements in 8 different coals (5 American, 2 Brazilian and 1 Spanish). The calculated partial concentrations of elements in organic and inorganic (sulfide, carbonate and sulfate) fractions were obtained. These results could be summarised...
Sixteen trace and minor elements that occur in coal are listed among 189 substances identified as hazardous air pollutants (HAPs) in the US Clean Air Act Amendments of 1990. We investigated the occurrence and cleanability of the 16 HAPs in Illinois coals, as a contribution to the discussion about the potential effect of pending environmental regulations on the future use of these coals in power...
The volatility of mercury can cause large errors during quantification when methods based on acid digestion are applied. In this study, mercury levels in coals have been determined by an atomic-absorption- based instrument hitherto not used with coals or coal-derived materials. The results have been compared with ?certified? values of reference materials. The instrument is relatively easy to use:...
The volatility of mercury can cause large errors during quantification when methods based on acid digestion are applied. In this study, mercury levels in coals have been determined by an atomic-absorption- based instrument hitherto not used with coals or coal-derived materials. The results have been compared with 'certified' values of reference materials. The instrument is relatively easy to use:...
An investigation of refuse-derived char (RDC) generated by thermolysis of municipal solid waste (MSW) was undertaken to elucidate the behaviour of some toxic and potentially toxic trace elements (Cr, Cu, Mn, Ni, Pb, Sb, and Zn) plus Fe during combustion of RDC. About 87% of Sb, 66% of Pb, 60% of Cu and significant parts of Fe>Zn>Ni>Mn>Cr from the RDC are volatile at 1200 o C, and...
Coal samples were obtained from a multigravity separator at Harworth (UK) coal-preparation plant. The minerals identified by X-ray diffraction in low-temperature ashes include kaolinite, illite, mixed-layer illite-smectite, chlorite, quartz, pyrite, apatite and gypsum. The latter is an artefact of the ashing procedure. Based on X-ray diffraction and major element analyses the coal samples show a preferential...
The rapid determination of elements present in low level concentrations in bituminous coals is possible using laser ablation-inductively coupled plasma-mass spectrometry (l.a.-i.c.p.-m.s.). A wide range of trace elements can routinely be determined using this technique but it is for environmentally sensitive elements, such as As, Cd, Mo, Sb, Se and Hg, that it is of most use due to the low levels...
Concentrations of trace elements in coal derived liquids have been investigated by inductively coupled plasma-mass spectrometry (ICP-MS) and by Mossbauer spectroscopy. Liquefaction extracts prepared from the Argonne Premium Coals and a coal tar pitch have been examined. Microwave digestion in concentrated nitric acid has been shown as a suitable method for determining trace element concentrations...
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 characterising coal fractions separated from coal samples using sink-float technique. It consists in the calculation of (a) organic element association...
In the absence of either standard methods for trace element analysis of coal-derived chars and ash or standard reference materials for coal gasification samples, a comparative exercise has been undertaken to validate analyses of chars and fines recovered from a coal gasification pilot plant. Several sample digestion methods, used for converting solid samples to aqueous solutions for trace element...
A review has been made of the various methods of determining major and trace element affinities for different phases, both mineral and organic in coals, citing their various strengths and weaknesses. These include mathematical deconvolution of chemical analyses, direct microanalysis, sequential extraction procedures and density fractionation.A new methodology combining density fractionation with mathematical...
Analyses of solid streams from a pilot-scale coal gasifier equipped with hot-gas filtration at 580 o C have indicated that all coal-derived mercury was carried away by the fuel gas. Calculations using a thermodynamic equilibrium model have confirmed that there was little potential for removal of mercury in the hot gas filter at these temperatures. In this work, several experimental capture/recovery...
This study focuses on the mobility of water-soluble major and trace elements in six Spanish fly ashes using room temperature open and closed and heated (90 o C) closed leaching systems in an attempt to reduce the content of undesirable species in coal combustion by-products to increase their potential applications.The leaching trends of the trace impurities are consistent with the dissolution...
The main aim of this study was a detailed comparison of trace element partitioning during combustion of bituminous coal and lignite in two circulating fluidised-bed units at 40 and 100% boiler output. The elements considered here are: S, Cl, Br, V, Cr, Co, Ni, Cu, Zn, Ge, As, Se, Sn, Sb, W, Hg, and Pb. The trace element concentrations in combustion products show enrichment of most of the elements...
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