Effect of pre-oxidation on galena in the flotation separation of chalcopyrite from galena with calcium lignosulfonate as depressant

Abstract

In this work, to achieve efficient separation of chalcopyrite from galena in Cu–Pb sulfide minerals, pre-oxidation by sodium persulfate (Na2S2O8) was used to magnify the differences in the floatability of two minerals in the presence of calcium lignosulfonate (CLS). The micro-flotation results of chalcopyrite and galena showed that pre-oxidation by Na2S2O8 could strengthen the depression performance of CLS on galena. The strengthening mechanism of Na2S2O8 to CLS adsorption onto the galena surface was revealed by local electrochemical impedance spectroscopy (LEIS), zeta-potential analysis, and X-ray photoelectron spectroscopy (XPS). LEIS showed that oxidation by Na2S2O8 contributed to the adsorption of CLS on the galena surface. XPS analysis demonstrated that the main oxidation species on the galena surface were PbSO4 and Pb(OH)+ in the presence of Na2S2O8 and that CLS interacted with oxidized galena by chemisorption. Zeta potential analysis indicated that a positive oxidation species was adsorbed on the galena surface; moreover, the oxidation species Pb(OH)+ endowed CLS on the galena surface with excellent adsorption performance. These findings are also supported by the results of the solution chemistry calculation. Galena also exhibits terrible surface reactivity and responds poorly to xanthate collectors after interaction with Na2S2O8 and CLS.