Mineralogical variations with the mining depth in the Congo Copperbelt: technical and environmental challenges in the hydrometallurgical processing of copper and cobalt ores

Abstract

For a long time in the Democratic Republic of Congo, the mining of ores for the production of copper cathodes and salts of cobalt was mostly conducted in the near-surface oxidized mineralization of the Congo Copperbelt. An important part of this mineralization is found in geological settings where copper and cobalt mainly exist as mixtures of oxides and sulfides. With the depletion of surface-rich minerals, mining is taking place at depths where sulfide minerals are prevalent. Using current technologies, the hydrometallurgical processing of ores with high levels of sulfide minerals results in poor metal recovery due to their retention in process wastes. These mineral wastes have the propensity to lead to Acid Mine Drainage (AMD) when exposed to rainfall and atmospheric air. Therefore, major changes in the technologies implemented will be needed in order to guarantee higher process efficiencies while endeavoring to uphold environment safeguarding reinforcement. This work aimed to demonstrate the urgency of updating the hydrometallurgical technologies implemented for the processing of coppercobalt ores with an emphasis put on minimizing the environmental footprint of process wastes. Four copper-cobalt deposits and downstream hydrometallurgical processes were surveyed to get a better understanding of how changes in mineralization occurring in the deposits will influence the processing Q3 technologies and practices during the management of process wastes.