Catalytic mechanism of silver in the oxidative dissolution process of chalcopyrite: Experiment and DFT calculation

Abstract In this work, combined techniques were utilized to interpret the catalytic mechanism of Ag + ions in sulfuric acid-ferric sulfate system of chalcopyrite. Density functional theory (DFT) calculations indicated the favorable adsorption of Ag + ions on reconstructed (001)-S and (112)-S surfaces of chalcopyrite, and confirmed the possibility of silver sulfide and sulfur vacancy formations. XPS analysis further indicated the formation of silver sulfide on chalcopyrite surface. Electrochemical analysis showed that silver catalyzed chalcopyrite dissolution by enhancing the electrochemical reactivity. In addition, the incorporation of silver atoms into the chalcopyrite surface might cause a major distortion in its structure and accelerated the diffusion rate of copper atoms mainly because of that the Cu + ionic radius is much smaller than that of Ag + . As a consequence, the accumulation of passivating species was prevented and the adverse effect of passivation layer mainly consisting of polysulfide and metallic oxides was reduced, thus resulting in high dissolution kinetics. According to the present work, a model for interpreting catalytic mechanisms of Ag + in chalcopyrite dissolution is provided.