Insight into selective depression of sodium thioglycallate on arsenopyrite flotation: Adsorption mechanism and constructure

Arsenopyrite is a hazardous substance exist in copper concentrate, thus causing serious environmental pollution during the smelting process. However, the selective depression of arsenopyrite remains a challenge to flotation. This study aims to analyze the depression mechanism of sodium thioglycallate (STG) towards arsenopyrite in the Cu-As separation flotation. Micro-flotation tests confirmed that STG was able to selectively depress arsenopyrite in chalcopyrite flotation and lowered As content in copper concentrate. Local electrochemical impedance spectroscopy (LEIS) demonstrated that STG preferred to adsorb on arsenopyrite than on chalcopyrite, which enhanced electrochemical impedance and reduced surface reactivity. Furthermore, surface adsorption test and contact angle measurement illustrated that STG hindered butyl xanthate (BX) adsorption on arsenopyrite surface, thus the wettability of arsenopyrite was further enhanced. The results of fourier transform infrared spectroscopy (FTIR), DFT caculation and Molecular dynamics simulations (MDS) revealed that STG chemically bond with Fe and As sites on the surface of arsenopyrite through its -SH group, and it formed a hydrogen bond with water molecules via its -COO- group at the top of molecule. Ultimately, a bridge-similar constructure was generated among arsenopyrite, STG and water molecules. This constructure resulted in a stable hydrophilic film covered on arsenopyrite surface, thus its flotability was severely deteriorated.