The unavoidable presence of ionic substances in the ore pulp can adversely effects on the separation of pyrite from other valuable metal sulfide ores. Developing new reagents to eliminate this effect is of great significance. In this study, a novel approach was proposed to depress pyrite by utilizing sodium trithiocarbonate (Na 2 CS 3 ) as a depressant in the lime-CuSO 4 system. The results of the micro-flotation experiments showed that a low dosage of Na 2 CS 3 in the lime-CuSO 4 system could effectively depress pyrite. The presence of CuSO 4 in the solution which improves the ability of BX to adsorb on the surface of the pyrite was also revealed by the analysis of LEIS, UV–Vis, and contact angle, while the addition of Na 2 CS 3 effectively hindered the adsorption of BX. XPS and SEM-EDS analysis results showed that Na 2 CS 3 forms a complex with Cu 2+ and adsorbs onto the pyrite surface, thereby impeding the adsorption of the collector and effectively depressing pyrite.
Copper ions have been widely used as activators in mineral flotation. However, in this study, it was found that copper ions can be used as auxiliary depressant for chalcopyrite depression, reversing the traditional use of copper ions as activators. In addition, a chalcopyrite depressant called sodium trithiocarbonate (Na 2 CS 3 ) has been proposed. Na 2 CS 3 was used as the main depressant and copper ions as the auxiliary depressant in this paper. Copper ions could enhance the depression effect of Na 2 CS 3 on chalcopyrite. The depression effect was reflected through micro-flotation tests, and the depression mechanisms were investigated by UV–Vis spectrophotometry determination, contact angle measurements, LEIS experiments, XPS tests, Zeta potential measurements and DFT simulation. The flotation results indicated that Na 2 CS 3 can depress chalcopyrite, and copper ions could enhance the depression effect of Na 2 CS 3 on chalcopyrite. UV–Vis spectrophotometry analysis shows that Na 2 CS 3 can reduce adsorption capacity of BX on chalcopyrite surface. Contact angle measurements and LEIS experiments indicate that hydrophilicity substance is formed after the addition of Na 2 CS 3 . XPS tests confirm that the Cu(OH) 2 produced by the addition of Na 2 CS 3 was mainly responsible for the depression. Zeta potential measurements and DFT simulation reveal the synergistic mechanism between copper ions and Na 2 CS 3 . The enhanced depression effect of copper ion is mainly achieved by promoting the desorption of BX and the formation of Cu(OH) 2 on chalcopyrite surface in the presence of Na 2 CS 3 .
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