Sulfur chemistry in metal sulfide oxidation

摘要

Oxidative pyrite degradation proceeds via polythionates in a novel cyclic pathway. Elemental sulfur is only a side-product of the reactions. At neutral pH polythionates accumulate to high amounts whereas in case of bacterial leaching at acidic pH mainly sulfate besides some elemental sulfur and polythionates are formed. Oxidative degradation of sphalerite (ZnS) and galena (PbS) does not proceed via polythionates. Instead, high amounts of elemental sulfur accumulate at acidic pH, reflecting a different degradation mechanism. This can be explained by the different crystal structure and the solubility of the metal sulfides. An understanding of the mechanism of metal sulfide oxidation may help to improve measures against the detrimental impact of acid rock drainage (ARD) or to improve coal desulfurizalion operations.