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.

Synchrotron Radiation Based Study of the Catalytic Mechanism of Ag+ to Chalcopyrite Bioleaching by Mesophilic and Thermophilic Cultures

“…This study also indicates that SR-techniques are useful to illustrate the dissolution mechanism during bioleaching and possible contribution of the catalytic effect of Ag + . However, due to the fact that the evolution of intermediates during bioleaching are mainly affected by the iron-and sulfur-oxidizing capabilities of bioleaching microorganisms (such as growth temperatures) [10,18], it is very interesting if the catalytic mechanisms of Ag + could be affected at different bioleaching conditions. Nevertheless, relevant studies have not been conducted and it deserves further investigation.…”