Occurrence and Environmental Features of Heavy Metal Elements of Coal from Coalfield in the Southeast Shanxi

The coal was sampled from No.15 coal seam in coalfield of southeast Shanxi. The Hg, As, Se, Cr and Pb occurrence in coal seam and environmental features of the heavy metal elements of coal were studied by X-ray fluorescence spectrometry (ARL Quant 'X), X-ray diffraction (XRD) and inductively couple-plasma mass spectrometry (ICP-MS). Environmental features, such as heavy metal element concentration, distribution and occurrence mode, etc., were studied by systematic determination of element concentration, inorganic element and mineral composition in coal. The results showed that the coal from No.15 coal seam had the mercury (Hg) concentration between 0.44 and 0.268 μg/g, and average Hg concentration of 0.11 μg/g; arsenic (As) concentration between 0.31 and 0.91 μg/g, 0.61 μg/g on average; selenium (Se) concentration between 0.94 and 3.56 μg/g, 2.45 μg/g on average; chromium (Cr) concentration between 9.54 and 24.58 μg/g, 17.06 μg/g on average; lead (Pb) concentration between 10.23 and 23.56 μg/g, 18.13 μg/g on average. The comparison with the Clark value showed Se was significantly enriched, As and Cr were lost, and Hg and Pb were normal. Compared with the coal from other counties and regions both at home and abroad, as was lost and other elements were normal. The elements irregularly distributed vertically. In spite of different element concentrations in adjacent coal seams, no significant enrichment occurred. The target elements mainly occurred in the form of inorganic matters except As. Hg was mainly concentrated in pyrite and clay minerals. Se, Cr and Pb were mainly concentrated in kaolinite, and Se was mainly concentrated in illite. Because of different occurrences or different forms in one mineral, the Hg, As, Se, Cr, and Pb loss rates were 99.43%, 85.91%, 77.89%, 73.81%, and 68.85% at 815°C, respectively.