Platinum-group elements in weathered Lower Group and Middle Group chromitites of the Bushveld Complex

All major sources of economically important platinum-group elements (PGE) are associated with sulfides and chromite in mafic-ultramafic rocks. The Bushveld Complex in South Africa is the largest PGE deposit worldwide. Chromitites of the Lower Group (LG) and Middle Group (MG) of the Bushveld Complex hold PGE contents of a few ppm. However, these chromitites are mainly mined for chromium only and extraction of PGE as a by-product is limited. Surface weathering in the area of the Bushveld Complex is up to 50 m down from surface. Attempts to recover Pt and Pd from these weathered ores lead to recoveries of <30 %, despite that Pt and Pd concentrations are similar in pristine and weathered ores. The recovery of PGE from near-surface chromitites of the LG and MG would increase the resource efficiency of current mining operations.. Therefore, an efficient utilization of these ores requires geochemical and mineralogical characterization of the PGE within these ores and the development of novel approaches of mineral beneficiation.