A critical review on flotation of oxidised PGM ores in view of the processing of Great Dyke ores: A focus on sulfidisation and collectors

The Great Dyke hosts vast reserves of platinum group metals (PGMs), however, the increasing depletion of PGM-bearing sulfide minerals has resulted in the need to process the difficult-to-recover oxidised PGMs from near-surface. The efficient recovery of oxidised PGMs remains a significant challenge in mineral processing due to their complex surface chemistry and poor response to conventional flotation techniques. This review provides a comprehensive overview of recent advances in the flotation of oxidised PGMs, highlighting the key factors influencing their behaviour including mineralogy, surface oxidation and reagent interactions – with a keen interest on collectors. The paper examines the mechanisms underlying the poor floatability of oxidised PGMs and evaluates various strategies developed to enhance their recovery. Pre-treatment methods and alternative collectors for the hydrophobisation of oxidised PGM mineral surfaces are discussed. Finally, the review outlines current knowledge gaps and recommends future research directions aimed at improving the flotation performance of oxidised PGMs. Findings of this work are important in supporting more sustainable and efficient resource utilisation in the PGM mining industry in line with the UN’s Sustainable Development Goal 12.