Hydrometallurgy

[PY1-43] Electrochemical studies of chalcopyrite dissolution in acidic chloride solutions

○Thao Thi Phuong Nguyen¹, Shushi Tsuji¹, Carlito Baltazar Tabelin¹, Mayumi Ito¹, Naoki Hiroyoshi¹ (1. Hokkaido University)

Keywords:chalcopyrite, electrochemical, impedance, acidic chloride solution

Chalcopyrite (CuFeS₂) dissolution in HCl solutions containing copper and iron ions depends on a redox potential determined by Fe³⁺/Fe²⁺ redox pair: dissolution rate increases with potential to reach maximum at a certain potential, then it decreases at higher potentials. To clarify the mechanism, anodic dissolution of a chalcopyrite electrode were studied in 0.1 kmol m^-3 HCl solutions at 25^oC under nitrogen atmosphere using conventional three-electrode system, and the effects of 0.1 kmol m^-3 Cu²⁺ and Fe²⁺ on the anodic polarization curves were investigated. Without the metal ions or with only Cu²⁺ or Fe²⁺, the anodic current increased monotonically with increasing potential. When both Cu²⁺ and Fe²⁺ were added, a large current peak appeared in the polarization curve at low potentials. A similar current peak was also observed when Cu⁺ was added, implying that Cu⁺ formed by the reduction of Cu²⁺ by Fe²⁺ in aqueous phase causes the current peak. Based on the results, a reaction model assuming the intermediate Cu₂S formed by the reaction between CuFeS₂ and Cu⁺ is discussed.