Geochemical characteristics and inorganic-organic affinity of the trace elements in Yimin lignite

The occurrence characteristic and contents of 32 trace elements in 15^# and 16^# coals in Yimin were analyzed using ICP-MS combined with demineralization and extraction of humic acid. Compared with Clark values and contents of trace element in Jurassic-Cretaceous coal in China and lignite in the world, there were no obvious enrichment of the trace elements in Yimin raw coal. Contents of most trace elements, expect Ni and As, in demineralized coals are lower than those in the raw coal. Some trace elements, Ni, Mo, Cd, Sn, and W significantly enriched in humic acid extracted from raw coal and demineralized coal, which indicates that these elements form the stable organic-compounds with humic acid. Meanwhile V, Ni and As were found to be enriched in raw coal and demineralized coal,which showed that the stable organic-compounds could be formed between V, Ni,As and coal macromolecule. 6 kinds of trace elements in Yimin coal are classified based on correlation coefficient between ash and trace element: inorganic enriched elements-Cr and U; inorganic affinity element-Cu, Cd, In, Sn, Ga, Y, Zr, Hf, Bi and Th; the tendency of inorganic affinity element-Be, Sc, Rb, Sr, Nb, Cs, Ta and Pb; the tendency of organic affinity element-V, Cr, Co, Cu, Se, Y, Mo, Cd, Sn, Sb, Ta and Tl; the organic affinity element-Li, Co and W; the organic enriched elements-Ni, Zn, Mo and Sb.