A comparative study of the dissolution of nickel and copper in acidified CuSO 4-acetonitrile-H 2O and CuCl 2-NaCl-H 2O solutions

Abstract

The electrochemistry of the dissolution of copper and nickel rotating disc electrodes in acidified CuSO 4-AN-H 2O and CuCl 2-NaCl-H 2O solutions was investigated. The rate constants calculated from electrochemical measurements indicate that the dissolution of copper in both CuCl 2-NaCl-H 2O and CuSO 4-AN-H 2O solutions, and nickel in CuCl 2-NaCl-H 2O solutions are all Cu(II) diffusion controlled. However, the dissolution of nickel in acidified CuSO 4-AN-H 2O solutions was shown to be controlled by the formation of a nickel oxide film. Rate constants for nickel dissolution were measured by three methods. Good agreement was obtained between the mixed potential predicted from polarization measurements and that observed in the dissolution process. These results contribute to a fundamental understanding of the reactivity of two comparable leach systems proposed for the processing of calcines derived from a segregation of dead roasted chalcopyrite/pentlandite concentrates.