Trace elements in Chinese coals and their partitioning during coal combustion

This paper gives a detail investigation about the trace elements (TEs) in t ypical Chinese coals, TEs partitioning during combustion and their differen t environment impacts. Firstly, it is determined that the contents of 9 TEs (As, Be, Cd, Co, Cr, C u, Ge, Ni, Pb) and 3 sulfur species (sulfate SO42-, sulfide S2- and Organic S-0) in 7 density fractions of Qingshan bituminous coal, and the TEs occur rence mode is studied with Solari (1989) model. Moreover, the contents of 1 2 TEs (including above-mentioned 9 TEs and Mn, V, Zn) in 7 Chinese typical coals are determined and chemometric methods (factor and cluster analysis) are used to investigate the TEs combination in these coals. Secondly, 8 fly ashes with 4 sizes are sampled during Qingshan bituminous c oal combustion in a thermal power plant. Higher temperature and reducing at mosphere are found to enhance greatly the metals enrichment in the submicro n and micrometer particles. An enrichment coefficient is used to describe t he TEs partitioning in the fly ash size-fractions and the results are discu ssed according to three factors: TEs combination in coals, combustion condi tion in a combustor, and fly ashes size. Finally it is also studied, by the sequential extraction analysis, that the TEs speciation in ashes (dregs and fly ashes) from Qingshan bituminous coa l combustion, in order to assess reasonably the TEs environmental impacts.