Flotation performance, structure–activity relationship and adsorption mechanism of a newly-synthesized collector for copper sulfide minerals in Gacun polymetallic ore

Highlights: • EICTU showed excellent flotation performance to copper sulfide minerals. • EICTU's geometry and electronic structures supported its flotation property. • EICTU was chemisorbed on copper sulfide mineral surfaces. • Normal covalent bond played a major role in their interaction. • Iron impurity was unbeneficial to EICTU adsorption on tetrahedrite surface. This study investigated the flotation performance, structure–activity relationship and adsorption mechanism of a newly-synthesized collector N-ethyl-N'-isopropoxycarbonyl thiourea (EICTU) for copper sulfide minerals in Gacun polymetallic ore. The bench-scale flotation test indicated that EICTU exhibited superior flotation performance to the copper sulfide minerals compared with conventional butyl xanthate (BX) and O-isopropyl-N-ethyl thionocarbamate (IPETC) collectors. The results of comparative test showed that among the three collectors EICTU had the strongest collecting ability and optimal selectivity for Cu²⁺/chalcopyrite. The structure–activity relationship study based on density functional theory (DFT) calculation supported the above conclusion. The adsorption mechanism analysis indicated that EICTU adsorption on copper sulfide mineral surfaces was a chemical process by separately generating normal covalent bond between carbonyl S atom and Cu atom and back donation covalent bond between carbonyl O atom and Cu atom, which was confirmed by FTIR spectrum analysis results. The lattice impurity iron is unfavorable to EICTU adsorption on tetrahedrite surface while zinc, arsenic and silver impurities had little effect. EICTU presents excellent collecting power and selectivity for copper sulfide minerals and thus it has great potential to be applied industrially.