Surface properties of copper-sulfide minerals with sodium-hydrosulfide activation

The surface properties of slightly oxidized chalcocite, bornite, and chalcopyrite with sodium hydrosulfide (NaHS) treatment were investigated by solid analyses of X-ray photoelectron spectroscopy, solution analyses, and zeta potential measurements. NaHS is known as a flotation activator for copper-oxide minerals by sulfurizing their surfaces. This study focused on the surface properties before/after sulfurization by the NaHS at several NaHS dosages and alkaline pHs. Iron leaching and precipitates of copper–iron-sulfide minerals have also been investigated. The analysis results showed that NaHS sulfurized the oxidized copper species, CuO and CuSO4, to copper sulfide, but oxidized iron species, Fe2O3 and Fe(OH)3, were not sulfurized by NaHS. These oxidized iron species dissolved into solutions as complex ion, Fe(HS)20, then Fe(HS)20 was decomposed by dissolved oxygen and reprecipitated as Fe2O3. The results of chalcocite showed that Cu2S was generated on the surfaces with NaHS treatment at any pH. The bornite and chalcopyrite results indicated that Fe2O3 was produced on bornite surfaces with an increase in pH, whereas the chalcopyrite surfaces were covered as the pH decreased. A flotation test was conducted using a Chilean copper ore that contained chalcocite, bornite, and chalcopyrite, and the flotation recovery of each mineral was consistent with the surface sulfurization at several NaHS dosages and pHs.