Role of magnesium-bearing silicates in the flotation of pyrite in the presence of serpentine slimes

Abstract

Flotation is the most effective separation solution used in sulphide ore beneficiation. In sulphide ore flotation, the interaction between the valuable sulphide minerals and the gangues are complex. Serpentine, a common magnesium-bearing silicate mineral in sulphide ores, can largely depress the flotation of the valuable sulphide minerals by adhering at their surfaces (i.e. slime-coating). In contrast, quartz can mitigate the depressing of the valuable minerals by serpentine. This work studied the effect of two common magnesium-bearing silicate minerals in sulphide ores (i.e. pyroxene and olivine) on the flotation of pyrite which was used as a model sulphide mineral. It was found that, similar to quartz, pyroxene and olivine could significantly improve the recovery of pyrite depressed by serpentine. Zeta potential measurements and turbidity experiments showed that serpentine could aggregate with pyroxene and olivine in aqueous solution via electrostatic interaction. Furthermore, DLVO calculation revealed that serpentine preferentially interacted with pyroxene and olivine rather than pyrite, resulting in increased pyrite recovery by stripping serpentine from pyrite surface