Recovery of chalcopyrite from galena using ellagic acid as a lead-selective and environmentally friendly inhibitor: experimental and mechanistic insights

This study explored the selective application of the environmentally friendly organic inhibitor ellagic acid (EA) in the flotation separation of galena from chalcopyrite. Single-mineral flotation experiments revealed that galena flotation recovery significantly decreased from approximately 95% to 6.16% following EA addition, while chalcopyrite maintained a high recovery of approximately 95%. In artificial mixed ore flotation effective separation was achieved under optimized conditions. This yielded a copper concentrates with a Cu grade of 29.73% and a recovery of 95.67%, as well as a lead grade of 8.39% with a recovery of 8.62%, resulting in a separation index of 15.30. Comprehensive analyses were conducted using various techniques, including X-ray photoelectron spectroscopy, density functional theory calculations, zeta potential measurements, time-of-flight secondary ion mass spectrometry, xanthate adsorption capacity, and contact angle measurements. These analyses suggested that the selective EA adsorption on the galena surface was the key mechanism underlying the separation. Under alkaline conditions, the deprotonated phenolic hydaoxyl groups in EA preferentially interact with Pb sites on galena, increasing surface hydrophilicity via the formation of -OH groups, oxides, and sulfur oxides. This interaction effectively occupied active sites on galena surface, inhibiting xanthate adsorption. However, EA exhibited minimal influence on the surface chemistry of chalcopyrite and its interaction with collectors, enhancing the wettability difference between the two minerals. These results demonstrated the feasibility of effectively separating these minerals using the proposed approach.