Reuse of Acid Mine Drainage─Based on the Selective Oxidation Mechanism and Flotation Separation Behavior of Copper Sulfide Ore via AOPs

Acid mine drainage (AMD) poses a considerable environmental challenge in copper sulfide mines due to its high concentration of sulfates and toxic metals. Consequently, the primary aim of this research is to comprehensively utilize AMD and develop an efficient and clean separation technology for Cu-S flotation. XRD and SEM results indicate that the treated AMD had a weak effect on the mineral surface properties and possesses the potential to be used as an aqueous medium in flotation. Comparative flotation experiments suggest that the flotation separation indexes obtained under low alkalinity conditions (pH = 8.5 ± 0.2) outperformed those achieved using lime high alkalinity processes. Closed-circuit experimental flotation results revealed that the Cu concentrate grade was 19.05%, with a copper recovery rate of 88.53%. Analyses utilizing LEIS, AFM, and ToF-SIMS demonstrated that the Fenton reagent in the treated AMD system significantly inhibited the adsorption of the collector sodium ethyl xanthate (SEX) on the pyrite surface, whereas its impact on chalcopyrite was relatively minor. Therefore, Cu-S flotation separation was successfully achieved on a laboratory scale using Fenton oxidative modification in a low alkalinity-treated AMD system. These findings provide a theoretical foundation and offer an innovative method for the extensive application of Cu-S flotation separation and AMD.