Selective adsorption behavior and mechanism of a high-performance depressant in the flotation separation of pyrite from talcum

Abstract

Galactomannan (GM) was used as depressant to facilitate the separation of pyrite from talcum. Compared with common depressant dextrin, GM not only possessed higher selectivity, but also GM was consumed approximately 87% lower than that of dextrin at the optimal separation point. The recovery of pyrite and talcum was 83.52% and 26.73% respectively with pH 4.7 and GM dosage of 40 mg/L, at which the pyrite could be effectively separated from talcum. However, the recovery of pyrite and talcum was 68.34% and 33.45% respectively with pH 4.3 and dextrin dosage of 300 mg/L. The selective depression mechanism of GM on talcum was investigated by Fourier transform infrared spectroscopy (FT-IR), zeta potential measurements, X-ray photoelectron sspectroscopy (XPS) and interaction energy calculation. It was found that the GM was adsorbed on pyrite through physisorption, however it was adsorbed on talcum by chemisorption. Mg was the main active site of talcum to react with GM. Since SBX (sodium butyl xanthate) was adsorbed on pyrite by chemisorption, which was stronger than the physisorption between GM and pyrite, SBX could still be adsorbed on pyrite in the presence of GM. The interaction energy between talcum and GM was much more negative than that between pyrite and GM, which indicated the interaction between talcum and GM was stronger. Meanwhile, the interaction energy between talcum and GM was more negative than that between talcum and SBX, which revealed that talcum preferred to adsorb GM in the presence of both GM and SBX. Therefore, GM preferred to interact with talcum and could selectively depress talcum in the separation of pyrite from talcum.