Combined effect and mechanism of visible light and Ag+ on chalcopyrite bioleaching

Abstract The effect and mechanism of visible light and Ag+ on chalcopyrite bioleaching were investigated in the presence of Acidithiobacillus ferrooxidans. The results of bioleaching tests revealed that the copper extraction was improved significantly when visible light and Ag+ were simultaneously present. By analyzing bioleaching parameters, scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy results: the accumulation of jarosite and the formation of covellite-like species led to the slow dissolution rate of chalcopyrite at the end period of bioleaching. The introduction of Ag+ resulted in the formation of Ag2S and Ag0 on the surface of chalcopyrite. And light illumination promoted the accumulation of Ag2S and Ag0 on chalcopyrite surface, thus reducing the resistance of the passivation layer. Further, light illumination increased the rate of charge transfer and promoted the dissolution of chalcopyrite.