Adsorption and depression mechanism of an environmentally friendly reagent in differential flotation of Cu–Fe sulphides

Utilization of large doses of inorganic reagents in mineral industry not only leads to high cost but also increases the toxicity in the environment. This research provides a new, environmentally friendly, biodegradable, and cost-effective depressant reagent, namely tricarboxylate sodium starch (TCSS), in chalcopyrite and pyrrhotite flotation systems. The selective depression and adsorption mechanism of TCSS on the two minerals were studied through the laboratory based measurements such as microflotation experiments, XPS spectral analysis, IR spectral analysis, adsorption amount analysis and zeta potential measurements. The addition of TCSS exhibited a much better depressive performance towards pyrrhotite than chalcopyrite in a wide pH range. Binary mineral flotation experiments indicated that an effective separation between the two minerals could be possible at a low concentration of TCSS, at which an improved recovery and grade of chalcopyrite of more than 75% could be achieved. All of the analytical measurements justified the flotation results and revealed that TCSS behaved differently with the two minerals. TCSS showed significantly much greater affinity towards pyrrhotite, the reason of which may be the presence of large amount of metal hydroxyl species on its surface.