Mineralogical control on the leaching properties of cobalt oxydes from DR Congo.

Oxidized Cu-Co ores are of major importance in the Congolese Copperbelt. They are dominantly processed in Katanga using acid leaching under reducing conditions to recover both copper and cobalt. However, most operations face a limit in the leaching yields of cobalt which usually do not exceed 80%. The aim of this research work is to better understand the complex mineralogy of Co-Cu-Mn oxides and their behaviour during acid leaching. For this purpose samples from different mineralisations have been selected and tested in the lab under similar conditions. Both the feed and the leaching residues have been analyzed using automated mineralogy to identify the leachability of individual minerals based on their chemistry and their textural attributes. Full analytical mapping has been performed using a Zeiss Mineralogic with 5µm resolution and about 3000 cts/spectra. The limited reactivity of some Co-bearing minerals has been demonstrated. Results are cross-corelated with analytical chemistry and X-ray diffraction to suggest an optimal process mineralogy methodology for monitoring acid leaching operations of these ores.