Geometallurgy of cobalt ores: A review

Cobalt (Co) is a transition metal featuring unique physical properties which makes its use critical for many high-tech applications such as high strength materials, magnets and most importantly, rechargeable batteries. The bulk of world cobalt output usually arises as a by-product of extracting other metals, mostly nickel (Ni) and copper (Cu), from a wide variety of deposit types mostly Cu-Co sediment-hosted deposits, but also Ni-Co laterites, Ni-Cu-Co sulphides or hydrothermal and volcanogenic deposits. Significant differences in ore properties (geochemistry, mineralogy, alteration and physical properties) exist between cobalt-containing deposits, as well as within a single deposit, which can host a range of ore types. Variability of cobalt ores makes it challenging to develop a single extraction or treatment process that will be able to accommodate all geometallurgical variation. Overall, there is a lack of fundamental knowledge on cobalt minerals and their processability. The recovery efficiency for cobalt is generally low, in particular for processes involving flotation and smelting, leading to significant cobalt losses to mine tailings or smelter slags. This paper starts by reviewing the main geometallurgical properties of cobalt ores, with a particular focus on ore mineralogy which exerts a significant control over ore processing behaviour and cobalt extraction, such as the oxidation state, i.e. oxide or sulphides which drives the selection of the processing route (leaching vs flotation), and the associated gangue mineralogy, which can affect acid consumption during leaching or flotation performance. The main processing routes and associated specific geometallurgical aspects of each deposit type are presented. The paper concludes on the future cobalt prospects, in terms of primary and secondary resources, cobalt processing and sustainable cobalt sourcing for which further research is needed.