Geological variations in the Merensky Reef at Bafokeng Rasimone Platinum Mine and its influence on flotation performance

The Merensky Reef of the Bushveld Complex of South Africa is marked by prominent lateral and vertical variations in its geology, platinum group element grade distribution and platinum group mineralogy. At Bafokeng Rasimone Platinum Mine on the western limb of the complex eleven distinct Merensky Reef facies have been identified. The reef facies show different mineral processing behaviour. Detailed geometallurgical characterisation of three reef facies (FW 1A contact, FW 3 pothole and pothole edge reef facies) at Bafokeng Rasimone Platinum Mine has been carried out in an attempt to understand differences in flotation performance. Results illustrate that the FW 1A contact facies has the best Pt and Pd grades and recoveries in the flotation concentrates and the pothole edge facies has the worst. The differences are related not only to mineralogical and textural characteristics of the platinum group minerals and base metal sulphides in the different facies, but also pertain to the geological position and the mineralogy of the host rocks that are introduced as dilution to achieve a realistic mining cut.