The Leaching of Chalcopyrite in Ferric Chloride and Ferric Sulfate Solutions

Abstract

The leaching of natural chalcopyrite was studied in both ferric chloride and ferric sulfate solutions. The morphology of leaching was studied by using a single chalcopyrite crystal and it appeared quite different with the two solutions. Ferric chloride produced a porous elemental sulfur layer whereas ferric sulfate resulted in the formation and peeling-off of an aggregate of plate-like crystals of elemental sulfur. Ferric chloride is a more effective reagent and this is attributable to the morphological characteristics of chalcopyrite leaching. The kinetics with both leachant solutions were found to be linear over an extended period, followed by an acceleration stage, as a result of an increase in reaction surface area. A comparison of the results obtained in a kinetic study of ferric chloride leaching and those of anodic dissolution of chalcopyrite in an acidic chloride solution revealed that the leaching rate and activation energies in both reactions were compatible.