THE DIRECT AND INDIRECT EFFECTS OF THE REAGENT SUITE ON FROTH STABILITY IN LABORATORY SCALE BATCH FLOTATION TESTS

摘要

In batch flotation tests conducted on ores from the Merensky Reef, changes in froth stability invariablyoccur with variations in the reagent suite. The main reagents are collectors (primary and secondary),activators, depressants and frothers. Of these reagents, frother alone has a direct effect on frothstability, whereas other reagents influence the nature of the particles entering the froth phase thusinfluencing froth stability indirectly. Since the particles entering and leaving the froth in a batchflotation system are continuously changing, the stability of the froth can vary. Under these conditionsthe simplest measure of froth stability is the measure of water recovery at a fixed froth height. Thebatch flotation system developed at UCT allows for the separation of gangue, which is entrainedrelative to gangue which is floated. It has been found that the presence of naturally floatable gangue(NFG) leads to froth stabilisation, whereas the presence of hydrophobic sulfide minerals may lead todestabilisation of the froth, depending on the hydrophobicity (contact angle) of the sulfide minerals.This can vary with ore type since particle shape and amount of particles present can influence theextent of destabilisation. At low depressant dosages sodium isobutyl xanthate (SIBX) always resultsin lower froth stability than sodium ethyl xanthate (SEX). The frothing nature of dithiophosphateleads to increased froth stability and the addition of copper sulfate results in destabilised froths.Increasing depressant dosage reduces the stabilising influence of NFG and the depressant type(guar or CMC) also affects froth stability. Frother can be used in an attempt to directly overcomethe destabilising effects of high depressant dosage. This work examines the effect of variations inthe reagent suite and uses water recovery to analyse these effects on the recovery of sulfide minerals,floatable gangue and entrained gangue.