Migration and distribution of fifteen toxic trace elements during the coal washing of the Kailuan Coalfield, Hebei Province, China

This study mainly deals with the contents, migration and distribution of 15 toxic trace elements, including Be, Cr, Co, Ni, Cu, Zn, Ga, As, Se, Mo, Tl, Pb, Th, U and Hg, in the Paleozoic coals from the Kailuan Coalfield and their washing products. The results showed that Cr, Ni, Cu, Zn, Pb and As are enriched in the raw coals. And all the 15 elements Could be removed from the the raw coals to the slime. Selenium and thorium are relatively enriched in the middlings, and most of the elements, with the exception of Tl, are enriched in the tailings, among which As enrichment ratio is the highest (34.4%). Accordingly, more attentions should be paid to As and Fig when tailing and coal slime are utilized, Based on maceral and mineral analysis, the authors supposed that the migration and distribution of the 15 elements during coal washing might be controlled by clay minerals and pyrites.