The effect of frother type and dosage on flotation performance in the presence of high depressant concentrations

The use of high dosages of polysaccharide depressants in order to depress the undesired naturally floatable gangue (NFG) present in ores beneficiated from the Bushveld Complex, South Africa, results in a significant decrease in the stability of flotation froths. These unstable froths can result in restricted mass pull and decreased valuable mineral recovery. Previous work using a single polyglycol ether type frother, DOW 200, has shown that an increase in frother dosage could be used to overcome the destabilisation of the froth to a certain extent and improve valuable mineral recovery. This resulted in an increase in water recovery and dilution of the concentrate by entrained material. This work extends this study to examine the effect of using a stronger frother, DOW 250, on the recovery of sulphide minerals and floatable gangue from a Merensky ore at different dosages of guar gum and CMC, which are typically used as depressants in the processing of Merensky ore. Results indicate that an increase in the strength of the frother resulted in a more robust froth. Depressant type also had an influence on results obtained.

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► Increased frother dosage resulted in increased froth stability.
► At high depressant dosage DOW 250’s performance was superior to that of DOW 200.
► Increased frother dosage led to increased mineral recovery at the expense of grade.