Element geochemistry and cleaning potential of the No. 11 coal seam from Antaibao mining district

Abstract

Based on the analyses of sulfur and 41 other elements in 8 channel samples of the No. 11 coal seam from Antaibao surface mine, Shanxi, China and 4 samples from the coal preparation plant of this mine, the distribution of the elements in the seam profile, their geochemical partitioning behavior during the coal cleaning and the genetic relationships between the both are studied. The conclusions are drawn as follows. The coal-forming environment was probably invaded by sea water during the post-stage of peatification, which results in the fact that the contents of As, Fe, S, etc. associated closely with sea water tend to increase toward the top of the seam, and that the kaolinite changes into illite and montmorillonite in the coal-sublayer near the roof. These elements studied are dominantly associated with kaolinite, pyrite, illite, montmorillonite, etc., of which the As, Pb, Mn, Cs, Co, Ni, etc. are mainly associated with sulfides, the Mo, V, Nb, Hf, REEs, Ta etc. mainly with kaolintie, the Mg, Al etc. mainly with epigenetic montmorillonite, and the Rb, Cr, Ba, Cu, K, Hg, etc. mainly with epigenetic illite. The physical coal cleaning is not only effective in the removal of ash and sulfur, but also in reducing the concentration of most major and trace elements. The elements Be, U, Sb, W, Br, Se, P, etc. are largely or partly organically bound showing a relatively low removability, while the removability of the other elements studied is more than 20%, of which the Mg, Mn, Hg, Fe, As, K, Al, Cs, and Cr associated mostly with the coarser or epigenetic minerals show a higher removability than that of ash. The distribution of the elements in the seam profile controls their partitioning behavior to a great degree during the coal cleaning processes.