The selective flotation of chalcopyrite against galena using alginate as a depressant

A possible action model of the sodium alginate adsorption on the mineral surfaces at the solid/water interface in flotation separation of chalcopyrite from galena. [Display omitted] •Chalcopyrite and galena floated well using dibutyl dithiophosphate as collector.•Sodium alginate exhibited strong depressant effect on the galena flotation.•Sodium alginate had little negative effect on the chalcopyrite flotation.•Sodium alginate could selectively and chemically adsorb on the galena surface. In this paper, sodium alginate was put forward as a flotation depressant for selectively separating the chalcopyrite from galena. The effects of the sodium alginate on the flotation performance of chalcopyrite and galena were studied using ammonium dibutyl dithiophosphate as the collector. The adsorption behaviors of sodium alginate on the mineral surfaces were investigated through surface analysis including zeta potential, FTIR spectra and XPS spectra analysis. The micro-flotation results showed that sodium alginate exhibited selective and strong depressant effect on the galena flotation while had little influence on the chalcopyrite flotation, whether it was added before or after the collector. The surface analysis results demonstrated that sodium alginate could selectively adsorb on the galena surface and then hinder the subsequent collector adsorption thus resulting in the hydrophilic galena surface. The selective adsorption mainly consisted of the interactions between the Pb2+ on the galena surface and the functional groups in sodium alginate. Sodium alginate did not adsorb on chalcopyrite surface or interfere with the collector coverage on chalcopyrite surface. Based on these findings, a possible adsorption model of the sodium alginate on the water-solid interface of the two minerals was proposed. The paper shows that sodium alginate has the potential to act as an effective, non-toxic depressant in the flotation of Cu-Pb polymetallic sulphide ores.