Investigation into the flotation response of a sulphide ore to depressant mixtures

The Merensky reef in the Bushveld Complex is well-known to contain a number of platinum group elements (PGEs). These PGEs are strongly associated with the sulphide minerals found in the Merensky reef. In order to recover the PGEs from the Merensky reef, a combination of reagents is used to optimise the flotation process by various operations across the Bushveld Complex. These reagents usually include; collectors, activators and depressants. The most common collectors are the xanthates, while the activator copper sulphate (CuSO₄) is most often used. The depressants, either carboxymethylcellulose (CMC) or modified guar gum (guar) are typical.This study examines the effect of blending depressants on the flotation response of a typical Merensky ore. The effect of each depressant, being guar and CMC, was examined in turn by changing the concentrations used in initial flotation tests; this was followed by blending guar and CMC in equal ratios by various procedures to determine the effects thereof. The depressants were blended in two ways: (1) premixed followed by a single conditioning stage and (2) stage wise; as primary and secondary depressants, each conditioned in turn.