Energy consumption for Kell hydrometallurgical refining versus conventional pyrometallurgical smelting and refining of PGM concentrates

The recovery of platinum group metals (PGM) from flotation concentrates traditionally relies on energy-intensive smelting processes, which are vulnerable to deleterious constituents like chromite and face rising energy costs in South Africa. The objective of this study is to assess an alternative approach, specifically the Kell process, a patented hydrometallurgical method designed to handle UG2 concentrates with insensitivity to chromite levels. This research employs a comparative analysis of the Kell process against conventional pyrometallurgical methods, focusing on three key unit operations: aqueous pressure oxidation, roasting of residues, and chlorination of precious metals. Results indicate that the Kell process significantly reduces energy consumption, particularly electricity, by eliminating the need for smelting. This viable alternative offers PGM producers a sustainable pathway forward amidst increasing energy challenges and evolving ore compositions. The findings suggest the Kell process could play a crucial role in modernizing PGM recovery practices, ultimately leading to an environmentally and economically more favorable method for processing PGM concentrates.