Adsorption of O-isopropyl-N-ethyl thionocarbamate on Cu sulfide ore minerals

The adsorption of the flotation collector O-isopropyl-N-ethyl thionocarbamate on air-exposed Cu metal, cuprite, chalcocite, covellite, cubanite, chalcopyrite, bornite and pyrite at pH similar to 6 has been investigated primarily by X-ray photoelectron spectroscopy. It was found that Cu-I oxide and sulfide surfaces conditioned in the collector solution were hydrophobic, regardless of whether the collector adsorbed as the anion (IPETC-), in protonated form (HIPETC), or as multilayer CuIPETC patches. The Cu-I native oxide layer on the metal was largely unaffected by the adsorbed collector. For surfaces at which chemisorption occurred, interaction of the S in the collector was directly with Cu in the metal or mineral surface, rather than via O. Apart from chalcocite, the main species adsorbed from the collector solution on to Cu-I oxide surfaces were different from those adsorbed on the sulfide minerals, in that the N was predominantly deprotonated in the former and protonated in the latter. On chalcocite, comparable amounts of IPETC and HIPETC were adsorbed. Adsorbed HIPETC was in good electrical contact with the surface of cubanite, chalcopyrite and bornite, presumably because of direct interaction with the mineral rather than adsorption on top of chemisorbed IPETC or FeOOH. Collector coverage of the Cu minerals correlated with the availability of Cu-OHsurf with which HIPETC could react. Coverage by collector adsorbed as HIPETC on pyrite surfaces was low, but not negligible, nevertheless conditioned abraded pyrite surfaces were not obviously hydrophobic. (C) 2014 Elsevier Ltd. All rights reserved.