Electrochemistry of the leaching of chalcopyrite

Lazaro-Baez, Maria Isabel (2001) Electrochemistry of the leaching of chalcopyrite. PhD thesis, Murdoch University.

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Abstract

The potential region in which chalcopyrite dissolves during the oxidative leaching of the mineral in ferric sulphate solutions has been established. These results have been modelled using an extended mixed-potential description of the system. The initial stages of the dissolution process have been studied using a chalcopyrite disk and a platinum ring electrode held at appropriate potentials for the detection of ferrous and cupric ions. These experiments have shown that the initial stages of oxidation of the mineral involve the formation of soluble sulphur species in addition to elemental sulphur. The ring-disk experiments are generally consistent with thiosulphate as this species. The effect of potential and various ratios of ferric to ferrous ions on the rate has been investigated by both electrochemical and chemical analysis techniques. The role of non-oxidative dissolution in the leaching of chalcopyrite has been explored and it has been shown that the initial rate of non-oxidative dissolution is significant and could exceed the oxidative rate at long leach times.