Geometallurgy of Cobalt Black Ores in the Katanga Copperbelt (Ruashi Cu-Co Deposit): A New Proposal for Enhancing Cobalt Recovery

Copper-cobalt deposits in the Central African Copperbelt belong to Sediment-Hosted Stratiform Copper (SHSC) type and are situated Neoproterozoic Katanga Supergroup. This paper describes detail geology, geochemistry hydrometallurgy of cobalt, with a special focus on Black Ore Mineralised Zone (BOMZ) unit from Ruashi Cu-Co deposit as case study. Based results fieldwork laboratory testing, it was concluded that BOMZ consists succession massive stratified dolostones, which weathered into carbonaceous clay dolostones clays. The Lower “Calcaire à Minéreaux Noirs Formation” (Lower CMN Formation) finely laminated at surface clayey siliceous dolostones. cobalt concentration weathering zone is due supergene enrichment, process linked formation cap. ore heterogenite associated minor amounts chrysocolla malachite. Minor carrollite, chalcopyrite, chalcocite bornite present unweathered fragments. grade both decreases within depth while copper increases. These changes reflect variation mineralogy malachite malachite, traces heterogenite, spherocobaltite, chalcocite, carrollite bornite. Cu (100xAS Cu/TCu) Co ratio (100 xAS Co/TCo), related mineralogy, oxide ores (Cu ≥ 75%) dominant mixed < 75%, containing sulphide chalcocite) can be differentiated CMN. absence talc low Ni, Mn Fe, one hand, high-grade BOMZ, other facilitate but require specific processing. Consequently, recovery requires application processing method based sulphuric acid (30 g/L) leaching under reducing conditions (300–350 mV) removal impurities > 95% ≈ 99%) pregnant leach solution (PLS) by solvent extraction (SX) prior precipitation hydroxide (40.5%). enabled achieving, after 8 h magnetic stirring (500 rpm), highest yield 93% Co, major elements (84%) (40%). latter forms main co-product exploitation. In contrast, for Fe remained smaller than 5%.