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Abstract: The mineralogical and geochemical characteristics of feed coals and their combustion by-products (fly ash and slag) from Hongyanchi (HONG) and Weihuliang (WEI) coal-fired power plants in Xinjiang Province, Northwest China, were investigated. The enrichment and partitioning behaviour, as well as the leaching potential of the major and trace elements in these combustion by-products were evaluated. Three feed coals from the two power plants (HC, WC1, and WC2) were characterised by medium-moisture contents, low- to medium-ash yields, high volatile matters, and low-S contents as well as low-mineral contents. Except B, Sr, and Ba in WC1 feed coal; P, Ti, V, Cr, Mn, Cu, Zn, Rb, and Ba in WC2 feed coal; and Ti, Mn, Cu, Zn, Rb, Sr, and Ba in the HC feed coal, most major and trace element concentrations were low compared with other Chinese coals and coals worldwide. Most trace element concentrations in the studied fly ashes (HA, WAf, and WAc) were even lower than their minimum and/or 25th percentile (P25) values reported for EU fly ashes, as were the element concentrations in the fly ash leachates. The studied fly ashes were all classified as type F fly ashes, with high glass contents as well as high SiO2/Al2O3 ratios in the glass matrix. Through enrichment factors, mass balance, and partitioning of elements, S, F, Cl, Hg, and B were highly volatile in both PCC plants. Tin, As, Se, Cu, and Zn were also moderately volatile, and they were enriched in fly ashes mainly by volatilisation/condensation. Iron and Mn were slightly enriched in slags, probably due to the high density of Fe–Mn-bearing phases. In the light of the above-mentioned properties, fly ashes and slags from the two power plants in Xinjiang will have a very high potential for a variety of uses, with very low environmental limitations. In summary, this study is demonstrating the high quality of Xinjiang coals with enormous coal reserves, and also the high quality of the combustion by-products that will be produced also in very high amounts in the near future. Major focus is on trace elements. [Copyright &y& Elsevier]

Abstract: The (co)-firing of low-cost alternative fuels is expected to increase in the forthcoming years in the EU because of the economic and environmental benefits provided by this technology. This study deals with the impact of the different coal/waste fuel ratio of the feed blend on the mineralogy, the chemical composition and especially on the leaching properties of fly ash. Different blends of coal, petroleum coke, sewage sludge, wood pellets, coal tailings and other minor biomass fuels were tested in PCC (pulverised coal combustion) and FBC (fluidized bed combustion) power plants. The co-firing of the studied blends did not drastically modify the mineralogy, bulk composition or the overall leaching of the fly ash obtained. This suggests that the co-firing process using the alternative fuels studied does not entail significant limitations in the re-use or management strategies of fly ash. [Copyright &y& Elsevier]

Abstract: In this study, the application of some zeolitised fly ashes and synthetic zeolites to the decontamination of the leachate produced in a municipal solid waste (MSW) treatment plant and to the liquid waste from a pig farm was analyzed. Thus, the reduction of organic matter (BOD and COD), ammonium and total nitrogen, phosphorus and metals contents after a zeolite treatment was evaluated. Several synthetic zeolites were tested: some commercial zeolites and other synthetic zeolites and zeolitised ashes obtained after a coal fly ash alkaline hydrothermal process. Two forms of contact between the zeolitic material and the liquid waste were tested: in a stirred tank and in a column. In addition, other variables determined were the amount of zeolite and the residence time. The results showed that zeolites, especially zeolitised fly ash, clearly produced a strong reduction in the leachate nitrogen and phosphorus content. [Copyright &y& Elsevier]