GEOCHEMICAL DISTRIBUTION OF TRACE-ELEMENTS IN COAL - MODELING AND ENVIRONMENTAL ASPECTS

The present work consists of verifying a theoretical model based on ma ss distribution of trace elements in coal. Many versions of the model were tested using 42 elements in 8 different coals (5 American, 2 Braz ilian and 1 Spanish). The calculated partial concentrations of element s in organic and inorganic (sulfide, carbonate and sulfate) fractions were obtained. These results could be summarised as following: B, Be, Br, Ge and V are associated to organic coal fraction while As, Cd, Co, Cu, Dy, Hg, Lu, Mo, Ni, Pb, Se, W and Zn occur mainly in sulfide mine rals and Ba, Cr, Cs, Ga, Mn, Rb, Sb, Sn, Sr, Ta, U and Zr are distribu ted in the non-sulfide fraction. Finally, the volatility of trace elem ents was estimated using the calculated partial concentrations in orga nic and sulfide fractions. The applicability of this parameter in rela ted environmental problems was discussed, comparing model results with experimental and theoretical literature data of the mobilisation of t hese species into atmosphere. (C) 1997 Elsevier Science Ltd.