Catalytic effect of visible light and Cd2+ on chalcopyrite bioleaching
(Key Laboratory of Biohydrometallurgy, Ministry of Education, School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China)
Abstract: The effects of visible light and Cd2+ ion on chalcopyrite bioleaching in the presence of Acidithiobacillus ferrooxidans (A. ferrooxidans) were studied by scanning electron microscopy (SEM), synchrotron radiation X-ray diffraction (SR-XRD), and X-ray photoelectron spectroscopy (XPS). The results of bioleaching after 28 days showed that the copper dissolution increased by 4.96% with only visible light, the presence of Cd2+ alone exerted slight inhibition effect on chalcopyrite dissolution and the concentration of dissolved copper increased by 14.70% with visible light and 50 mg/L Cd2+. The results of chemical leaching showed that visible light can promote the circulation of iron. SEM results showed that Cd2+ promoted the attachment of A. ferrooxidans on chalcopyrite surface under visible light. SR-XRD and XPS results indicated that visible light and Cd2+ promoted chalcopyrite dissolution, but did not inhibit the formation of passivation. Finally, a model of synergistic catalysis mechanism of visible light and Cd2+ on chalcopyrite bioleaching was proposed.
Key words: bioleaching; chalcopyrite; Cd2+; Acidithiobacillus ferrooxidans; visible light