Leaching of chalcopyrite with ferric ion. Part I: General aspects

This paper presents a review of the literature on chalcopyrite leaching with ferric sulphate in acid medium. The effects of several parameters (ferric salt anion, oxidant concentration, pH and temperature) are examined and possible explanations are offered for the passivation of this sulphide during dissolution. The main theories related with chalcopyrite passivation point to the formation of a diffusion layer surrounding the chalcopyrite during dissolution, consisting of: bimetallic sulphide, copper polysulphide with a deficit of iron with respect to chalcopyrite, and elemental sulphur. Recent studies suggest that ferric ion plays two important and opposite roles in this process: as a mineral oxidizing agent and as the agent responsible for chalcopyrite passivation.