Evolution of Leaching Products on the Surface of Chalcopyrite by Mesophiles and Thermophiles Based on SR-XRD and XANES Spectroscopy

Abstract

The bioleaching experiments of chalcopyrite were conducted with single and mixed mesophiles (30 °C) and moderate thermophiles (45 °C) and extreme thermophile (65 °C), respectively, and analyzed by synchrotron radiation (SR) based X-ray diffraction (XRD) and X-ray absorption near edge structure (XANES) spectroscopy. The results showed that the copper extraction of chalcopyrite could be significantly promoted by bioleaching microorganisms, and the promotion effects for both the mixed cultures grown at different temperature and the different cells grown at the same temperature were significantly different. The surface of chalcopyrite after bioleached by the mixed or sole cultures are serious corroded and became complicated. More S0 was found to form in the sole cultures of specific iron-oxidizing microorganism L. ferrooxidans and L. ferriphilum and sulfur-oxidizing microorganisms A. thiooxidans and A. caldus cultures. Jarosite and secondary minerals (chalcocite and covellite) were detected for the mixed cultures and sole cultures of iron/sulfur-oxidizing microorganisms. The evolution of chalcocite and covellite were just relevant to the potential of leaching solution, no matter which cultures were used, where chalcocite could be formed at Eh value less than 500 mV and then converted to covellite at Eh value ~550 mV.