Selective passivation behavior of galena surface by sulfuric acid and a novel flotation separation method for copper-lead sulfide ore without collector and inhibitor

Here, we present a novel efficient passivation-separation method for galena and chalcopyrite that includes a novel sulfuric acid selective passivation process for galena and a special flotation process in which conventional inhibitors and collectors are not added. The surface passivation mechanism of galena was characterized by surface contact angle measurements, scanning electron and dispersive spectrometry (SEM-EDS) analysis and X-ray photoelectron spectroscopy (XPS) analysis. The contact angle measurements indicated that sulfuric acid passivation increased the surface hydrophobicity difference between galena and chalcopyrite, which led to the large difference in their floatabilities. The results of the passivation-flotation experiments for the galena-chalcopyrite mixture confirmed that the selective inhibition of galena was realized with this new process, and the floatability of galena was drastically reduced while that of chalcopyrite was slightly promoted; thus, the efficient separation of galena and chalcopyrite was achieved only with the addition of frothers. The SEM-EDS and XPS results revealed that the S element on the galena surface was gradually oxidized from S2− to SO42− during the passivation process, which generated a layer of hydrophilic lead sulfate (PbSO4), while a layer of floatable copper sulfides was formed on the surface of chalcopyrite. In this study, a new highly efficient copper-lead sulfide ore separation method was developed, and the interrelated mechanism was studied in detail.