The selective separation of molybdenite and talc is still a challenging problem owing to its excellent inherent hydrophobicity. In this study, sodium carboxymethyl starch was evaluated for the first time as a cost-effective talc depressant to achieve the molybdenite-talc separation with sodium diethyldithiocarbamate, a collector widely used to float sulfide minerals. The single-mineral and multi-mineral flotation tests witness carboxymethyl starch has shown a selective depression on talc and has little effect on molybdenite recovery with sodium diethyldithiocarbamate as a collector, terpineol as a frother and pH = 8 ± 0.5 (at an industrially relevant pH). Furthermore, experimental comparison of FTIR, equilibrium adsorption and XPS analysis demonstrate that the adsorption of sodium carboxymethyl starch on the talc surface can be considered to be irreversible under these conditions, and the higher adsorption density of sodium diethyldithiocarbamate on molybdenite over talc has highlighted the importance of differential adsorption density in the predictions of the efficient separation of molybdenite and talc. The innovative method may be applied efficiently in industrial applications to improve the comprehensive utilization of resources.
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