Auxiliary depression of copper ion - strengthening the depression of sodium trithiocarbonate on chalcopyrite

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 (Na2CS3) has been proposed. Na2CS3 was used as the main depressant and copper ions as the auxiliary depressant in this paper. Copper ions could enhance the depression effect of Na2CS3 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 Na2CS3 can depress chalcopyrite, and copper ions could enhance the depression effect of Na2CS3 on chalcopyrite. UV-Vis spectrophotometry analysis shows that Na2CS3 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 Na2CS3. XPS tests confirm that the Cu(OH)2 produced by the addition of Na2CS3 was mainly responsible for the depression. Zeta potential measurements and DFT simulation reveal the synergistic mechanism between copper ions and Na2CS3. 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 Na2CS3.