Flotation Behavior and Mechanism of Pyrite in Different Collector Systems: An Electrochemical and DFTB Study

Pyrite is one of the most common sulfide minerals in polymetallic sulfide ores, and its flotation behavior directly affects the selective separation efficiency of valuable minerals. This study investigated the effects of collector type, pulp pH, pH regulator, and combined collector ratio on pyrite flotation using sodium butyl xanthate (SBX), diethyl dithiocarbamate (DDTC), ammonium dibutyl dithiophosphate (ADDP), and Aerophine 3418A (3418A), together with cyclic voltammetry (CV) and DFTB analyses. The results showed that DDTC and SBX exhibited stronger collecting ability than 3418A and ADDP at natural pH. Increasing pH significantly depressed pyrite flotation, with CaO exerting stronger inhibition than NaOH. Combined collectors displayed pronounced component dependence and ratio sensitivity. CV results indicated that collector adsorption on pyrite is an irreversible electrochemical process, and that calcium-bearing species in the CaO system passivate surface active sites, thereby inhibiting collector adsorption. DFTB calculations revealed that collecting performance is governed by the coordination stability of double-bonded S atoms with surface Fe sites and resistance to hydration. The research results can provide a theoretical basis for regulating pyrite flotation behavior and optimizing reagent regimes in the flotation separation process of complex sulfide ores.