Comparative study of S, Fe and Cu speciation transformation during chalcopyrite bioleaching by mixed mesophiles and mixed thermophiles

摘要

The bioleaching experiments of chalcopyrite were conducted with mixed mesophilic cultures (30°C), moderate thermophilic cultures (45°C) and extreme thermophilic cultures (65°C), respectively. During bioleaching, the S/Fe/Cu speciation were analyzed by synchrotron radiation (SR) based X-ray diffraction (XRD) and S, Fe and Cu K-edge X-ray absorption near edge structure (XANES) spectroscopy. The results showed that the chalcopyrite dissolution could be significantly promoted by these mixed cultures, and the promotion effects were enhanced with the increase of leaching temperature. The formation of intermediates S , jarosite and secondary minerals (chalcocite, bornite and covellite) was detected during bioleaching, in which the formation of bornite, chalcocite and covellite was just related with the redox potential. The formation of bornite could accelerate chalcopyrite dissolution, while the decreasing of bioleaching microorganisms could reduce chalcopyrite dissolution.