Cryo-ToF-SIMS study of sodium isobutyl xanthate adsorption on sulfide minerals

Abstract

The chemical properties of the mineral/solution interface have a decisive influence on the flotation behavior of minerals. Here, chalcopyrite, chalcopyrite-pyrite mixture, and chalcopyrite-galena mixture were reacted in 0.1 mM sodium isobutyl xanthate solution at natural pH, then centrifuged, fast-frozen, and characterized with time-of-flight secondary ion mass spectrometry at –125 °C (Cryo-ToF-SIMS) in comparison with the samples thawed in vacuum and measured at room temperature (RT-ToF-SIMS). Cryo-ToF-SIMS of fast-frozen mineral wet pastes allows quasi-in situ characterization of chemical species within the mineral/solution interfacial layer. It was found that dixanthogen was the predominant species of xanthate adsorption products on chalcopyrite and pyrite, while that of galena was lead isobutyl xanthate. In particular, due to the interaction effects between sulfide minerals, the formation of dixanthogen at the mineral/solution interface of chalcopyrite was promoted and inhibited by pyrite and galena, respectively, and the lead ions dissolved from galena were adsorbed to the chalcopyrite surface, resulting in xanthate to react with adsorbed species of lead ions to form lead isobutyl xanthate. This study also observed that the mineral/solution interfacial layer of chalcopyrite-galena mixture was more deficient in sodium ions and calcium ions than those of chalcopyrite and chalcopyrite-pyrite mixture; we proposed that this phenomenon was caused by the repulsion of sodium ions and calcium ions by lead ions dissolved from galena in the electric double layer of minerals.