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

The separation of galena (PbS) from chalcopyrite (CuFeS 2 ) requires strong oxidants for the depression of PbS, due to the excellent hydrophobicity of PbS. In this work, an advanced oxidation process, i.e., S 2 O 8 2− /Fe 2+ treatment, was employed to selectively depress PbS. The parameters of the S 2 O 8 2− /Fe 2+ process were determined via flotation tests as follows: pH 3, 1:1 S 2 O 8 2− : Fe 2+ molar ratio, and 10 min reaction time. The S 2 O 8 2− /Fe 2+ treatment selectivity decreased the hydrophobicity of the PbS surface. UV–vis spectroscopy results revealed that SO 4 − (major species) and OH radicals were produced in solution by the activation of Fe 2+ . The SO 4 − / OH radicals reacted with the PbS surface, generating the SO 4 2− and PbSO 4 species. These species coated the PbS surface, forming a hydrophilic PbS surface and inhibiting the PbS flotation. By contrast, the S 2 O 8 2− /Fe 2+ treatment generated only a minimal amount of SO 4 2− (5.98 % of the total S species) on the CuFeS 2 surface. Therefore, the CuFeS 2 surface was hydrophobic and CuFeS 2 particles could still be floated into the foam phase. This study provides a promising method for the selective depression of PbS in the PbS-CuFeS 2 mixture.