Depression Mechanism of a Novel Depressant on Serpentine Surfaces and Its Application to the Selective Separation of Chalcopyrite from Serpentine

Serpentine, a typically magnesium phyllosilicate gangue mineral, is often associated with chalcopyrite. In the process of flotation, serpentine is easy to get into the concentrate together with useful minerals, which seriously affects the quality of concentrate products. In this study, galactomannan (GM) was introduced for effectively separating chalcopyrite from serpentine with sodium butyl xanthate used as the collector. Its depression performance and adsorption mechanism were investigated through micro-flotation tests, zeta potential, FTIR, and XPS measurements. Micro-flotation test results showed that GM depressed serpentine more stronger than that of the chalcopyrite at a wide pH range of 3-8. An excellent separation of chalcopyrite and serpentine was achieved using GM as the depressant with a lower dosage of 40 mg/L, for which the flotation recovery of chalcopyrite was more than 80% and that of serpentine was close to 0. Zeta potential, FTIR, and XPS results illustrated that GM was chemically adsorbed on the serpentine surface through the interaction of the hydroxyl groups of GM with the Mg atoms on the serpentine surface. The formation of Mg(OH)(2) enhanced the hydrophilicity of serpentine and inhibited the adsorption of flotation reagents onto the serpentine surface, and thereby decreasing its floatability. Therefore, GM could be used as a potential depressant of serpentine owing to its high selectivity, low dosage, environment protection, and low cost.