Selective depression of galena in the galena and chalcopyrite system by the Fe(II)-activated persulfate process

• Published in: Minerals engineering 2024-10, Vol.217, p.108969, Article 108969
• Main Authors: Cao, Qinbo, Yan, Yan, Zou, Heng, Zhang, Haiyu, Liu, Dianwen, Wen, Shuming, Li, Yanjun
• Format: Article
• Language: English
• Subjects: Advanced oxidation process; Galena flotation; Hydrophobicity; Sulfate radical
• ISSN: 0892-6875
• DOI: 10.1016/j.mineng.2024.108969

•The S2O82−/Fe2+ system selectively depressed PbS in the PbS-CuFeS2 mixture.•The S2O82−/Fe2+ process decreased the hydrophobicity of the PbS surface.•The S2− on the PbS surface was oxidized to SO42− by the S2O82−/Fe2+ system.•The SO4− radicals are the primary oxidants in the S2O82−/Fe2+ system.•The S2O82−/Fe2+ process could not efficiently oxidize the CuFeS2 surface. The separation of galena (PbS) from chalcopyrite (CuFeS2) requires strong oxidants for the depression of PbS, due to the excellent hydrophobicity of PbS. In this work, an advanced oxidation process, i.e., S2O82−/Fe2+ treatment, was employed to selectively depress PbS. The parameters of the S2O82−/Fe2+ process were determined via flotation tests as follows: pH 3, 1:1 S2O82−: Fe2+ molar ratio, and 10 min reaction time. The S2O82−/Fe2+ treatment selectivity decreased the hydrophobicity of the PbS surface. UV–vis spectroscopy results revealed that SO4− (major species) and OH radicals were produced in solution by the activation of Fe2+. The SO4−/OH radicals reacted with the PbS surface, generating the SO42− and PbSO4 species. These species coated the PbS surface, forming a hydrophilic PbS surface and inhibiting the PbS flotation. By contrast, the S2O82−/Fe2+ treatment generated only a minimal amount of SO42− (5.98 % of the total S species) on the CuFeS2 surface. Therefore, the CuFeS2 surface was hydrophobic and CuFeS2 particles could still be floated into the foam phase. This study provides a promising method for the selective depression of PbS in the PbS-CuFeS2 mixture.