Abstract
Processing of weathered material from UG2 ore for recovery of Platinum group minerals (PGMs) is a challenging task due to poor recoveries and high chromite grade in the flotation concentrates. The flotation behaviour of the weathered and non-weathered ores of Middle Group 4 (MG 4) was investigated at different mining pit depths using sodium isobutyl xanthate as a collector, Sendep 30D as depressant and Senfroth 200 as a frother. The milling tests work were conducted prior to flotation. The results depicted that, the weathered ore is relatively soft and contained less chrome content as compared to non-weathered ore. The head grades of the surface ore and at a pit depth of 918 m was relatively the same assaying at 2.49 and 2.62 ppm respectively for the 4Es (Platinum, Palladium, Rhodium and Gold). The recovery and grade of PGMs at the rougher flotation cell was increasing with the increase in pit depth with the concentrate from surface weathered ore assaying 22.40 ppm and 47.07 ppm for the ore from 918 m depth for 4 Es. High chromite content in the flotation concentrate is due to blending of pristine ore and oxidized ore. Therefore, the correlation between degree of weathering, pit depth and recovery can be drawn for MG4 ore.