The synergistic depression phenomenon of an organic and inorganic reagent on FeS2 in CuS flotation scheme

The depression of pyrite (FeS 2 ) through an organic depressant is not only ineffective but also nonselective which causes poor selectivity . In this research, the depression effect of an organic polymer ‘poly-γ-glutamic acid (γ-PGA, a widely available class of polysaccharides)’ on pyrite flotation was improved by the addition of lime (CaO). The most encouraging flotation results were received at relatively lower concentrations of CaO and γ-PGA. The addition of CaO and γ-PGA had a synergistic inhibitory effect on pyrite flotation with a minor compromise in terms of the chalcopyrite grade at low alkaline conditions (pH 9). Adsorption studies and zeta potential measurements revealed that both CaO and γ-PGA were greatly adsorbed onto the pyrite surface than chalcopyrite. The addition of CaO and γ-PGA underwent a two-step depression effect on pyrite surface: (1) calcium species dissolved from CaO prefrentially adsorbed onto the pyrite surface and decreasing its negative charges; (2) pre-adsorbed calcium hydroxyl species promoted the adsorption of γ-PGA onto the pyrite surface. The XPS and FT-IR measurements revealed that γ-PGA formed the chemical coordination bonds with Ca-species on pyrite surface. Based on these measurement analyses, a two-step depression mechanism of CaO and γ-PGA on pyrite was also proposed. The envisaged scheme has its own benefits of environmental friendliness and cost-effective characteristics in Cu S flotation systems.