Complexity of Chalcopyrite Mineral Affecting Copper Recovery During Leaching

Abstract

Regardless of the media/solvent used, chalcopyrite (CuFeS 2 ) is highly refractory and is considered to be one of the most difficult to leach. Its leaching is slow and incomplete owing to the diffusion barrier formed that prevents further attack of the leaching solution (solvent) on the unreacted CuFeS 2 mineral surface. The nature and composition of this barrier, together with the dissolution mechanism, remain controversial. There are three hypotheses for the structure of the formed diffusion barrier. The first hypothesis is that elemental sulfur (S o ), formed during leaching, prevents further diffusion of the reactant from reaching the un-leached chalcopyrite. The second hypothesis, commonly cited, ascribes the poor leaching to the formation of Cu-rich polysulfides, promoted by Fe preferential dissolution occurring through solid-state transformation (metal-deficient sulfide). The third hypothesis blames iron-precipitates including jarosite, jarosite-like species, and goethite. This book chapter aims to explore the various challenges related to the mineralogy of chalcopyrite that affect the recovery of copper during the leaching process.