Effect of sodium sulfide waste water recycling on the separation of chalcopyrite and molybdenite

The effect of sodium sulfide waste water recycling on the separation of chalcopyrite and molybdenite was investigated in this work. The waste water, which was separated from the slurry after selective flotation, was recycled in the flotation system. This operation significantly improved the subsequent flotation of chalcopyrite and saved the reagent. The results showed that the depression efficiency of sodium sulfide gradually disappeared in the recycling tests due to the consumption. The consumption of sodium sulfide in the separation was not only caused by the adsorption on mineral surfaces but also resulted from the precipitation of metal ions which released from minerals. These effects decreased the solution reducibility and the adsorption of hydrosulfide ions, finally resulting in the less depression for chalcopyrite flotation. After adding a certain amount of sodium sulfide to the recycling, the depression of chalcopyrite performed well and the pulp potential maintained at a relatively lower level. Moreover, the pulp potential was an available parameter to control the flotation separation of chalcopyrite and molybdenite, which made the method easily applied to industry.