Reducing quartz gangue entrainment in sulphide ore flotation by high molecular weight polyethylene oxide

Polyethylene oxide (PEO) was tested to flocculate and depress fine quartz particles in the batch flotation of artificial mixtures of chalcopyrite–quartz as well as a commercial Au–Cu sulphide ore sample. The aggregation/dispersion behaviors of quartz, chalcopyrite and their mixtures in the presence of PEO with and without potassium amyl xanthate (KAX) were studied by photometric dispersion analysis (PDA), scanning electron microscopy (SEM) and zeta potential measurements. Batch flotation results indicated that the addition of low dosages of PEO improved value mineral recovery and concentrate grade during the flotation of both the artificial mixtures of chalcopyrite–quartz and the Au–Cu sulphide ore sample. Aggregation/dispersion test results revealed that the PEO caused non-selective flocculation of quartz and chalcopyrite, forming large hetero-aggregates. However, the addition of KAX caused the chalcopyrite particles to break away from the hetero-aggregates, leading to separate homo-aggregates of quartz and chalcopyrite. The flotation of the fine chalcopyrite and the depression of the fine quartz were thus both improved.