Insights into the distribution characteristic changes of leaching solution in the gap between chalcopyrite and passivation layer with polyvinyl pyrrolidone: A molecular view

Abstract

The passivation layer was proven to be an inevitable factor that prevents chalcopyrite leaching. Sulfur and jarosite are the commonly investigated substances in passivation layer research. In this study, the distribution characteristics of leaching solution in the gap between chalcopyrite and jarosite and between chalcopyrite and sulfur were investigated deeply at a molecular level. And the equilibrium distribution configurations were calculated. When polyvinyl pyrrolidone (PVP) was added, a significant layer formed near chalcopyrite. It prevented the accumulation of SO42− and thus prevent the formation of the passivation layer near chalcopyrite. Additionally, the increased diffusion coefficient of H2O molecules indicated the increased permeability and mobility of the leaching solution between chalcopyrite and passivation layer by PVP. Moreover, the increased diffusion coefficients of SO42− between chalcopyrite and sulfur referred to the enhanced dissolution of sulfur. Thus, chalcopyrite leaching was enhanced by PVP. The results provide a new view for the deep understanding of the enhancement mechanism of surfactants in chalcopyrite hydrometallurgy.