Zeta potential study of pentlandite in the presence of serpentine and dissolved mineral species

•Zeta potential was used to study the system pentlandite–serpentine.•Tests were designed to approach actual flotation conditions.•Pentlandite and serpentine alone showed slime coating will occur at flotation pH (10).•Pentlandite suspended in supernatant showed a charge reversal attributed to Mg ions.•Mixed minerals in supernatant revealed combined effect of Mg ions and slime coating.

Pentlandite and serpentine specimens were obtained from a sample of an ultramafic deposit to explore interactions that might be factors in processing by flotation. Zeta potential was measured under conditions designed to progressively approach the environment under which flotation will be attempted: viz. pentlandite and serpentine alone with indifferent background electrolyte; pentlandite conditioned in the presence of serpentine with indifferent background electrolyte; pentlandite conditioned in the presence of serpentine with supernatant derived from an ore suspension as background electrolyte. The “single mineral” experiments showed that hetero-aggregation is expected and was confirmed in the “mixed mineral” experiments. In the presence of supernatant uptake of Mg(OH)2 precipitates was detected and confirmed by tests using solutions doped with Mg ions and by surface analysis using scanning electron microscopy.