The solubility of copper sulfides under reducing conditions

The formation of copper thio-complexes in sulfide solutions has been recognized for many years, and the measured solubilities of certain copper sulfide minerals are attributed to these complexes. Attempts to model this system have proposed either copper(I) or copper(II) thio-complexes. These species have been incorporated into computer programs for generating stability diagrams for the copper–sulfur–water system in order to delineate the region where the reductive dissolution of copper sulfide minerals is likely. In this paper, it is proposed that the dissolution of copper from both ore bodies and sulfide tailings can be explained by the formation of the cupro-thio-complexes under anaerobic conditions. Stability diagrams are presented to depict the region and extent of the solubility. It is concluded that the stability diagrams involving copper(I) thio-complexes better represent the system.