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

Abstract The bioleaching experiments of chalcopyrite were conducted with mixed mesophilic culture (30 °C), moderately thermophilic culture (45 °C) and extremely thermophilic culture (65 °C), respectively. During bioleaching, the S/Fe/Cu speciation was 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 bioleaching temperature. For all bioleaching tests, the formation of intermediates S 0 , jarosite and secondary minerals (chalcocite, bornite and covellite) was detected, in which the formation of bornite, chalcocite and covellite was just related with redox potential. The formation of bornite could accelerate chalcopyrite dissolution, while the decrease of bioleaching microorganisms could reduce chalcopyrite dissolution.