CONCENTRATED CUPRIC CHLORIDE SOLUTIONS: POSSIBILITIES OFFERED IN COPPER PRODUCTION

This study presents the advantages of chloride media as a leaching media for sulfide minerals. The advantage in using cupric chloride solution as a leaching media is its ability to form complexes, which increases the redox potential and thus the oxidative power of the solution remarkably. The thermodynamics of the solution are discussed and the prevailing species suggested. Cuprous ion can be suggested to be present mostly as [CuCl3]2- but also partly as [CuCl2]-. The complexation of cupric ion is more inconsistent, but it can be suggested that cupric ion is not totally in a complex form. With lower chloride concentrations Cu2+ may not form complexes. At high Cl concentrations [CuCl]+ or [CuCl3]- and [CuCl4]2- may be present. Some chloride based processes are compared and the most significant processes, such as CLEAR, CYMET, and HydroCopper®, which have reached commercial application, are discussed. One of the advantages in the HydroCopper® process is that up to 95% of sulfur can be recovered in elemental form. A solid basis for obtaining high-quality copper involves a five-step refining process, including the removal of Cu2+ and sulfate, silver removal, neutralization, ion exchange, and finally precipitation of Cu2O. Although the technology of the HydroCopper® process is not new, innovation combined with established technology makes this process unique.