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.