Enhancing flotation separation of chalcopyrite and galena by the surface synergism between sodium sulfite and sodium lignosulfonate

In this study, the inhibitory effect of a composite depressant consisting of sodium sulfite and sodium lignosulfonate mixed at a molar ratio of 5:1 on Cu–Pb flotation separation was analyzed. The results of the mineral flotation tests show that both chalcopyrite and galena are floatable in a pH range of 6–12 and the composite depressant has a stronger inhibitory effect on galena than that of single inhibitors. The particle-size analyses of the concentrates and tailings show that it is difficult to inhibit the floatability of fine-grained galena using a single depressant, but the composite depressant can effectively deteriorate its floatability. The results obtained from zeta potential measurements and SEM reveal that the zeta potential of galena becomes more negative after a composite depressant is added because of the greater adsorption of sulfite and lignosulfonate ions on the surface of the galena. The XPS results show that sodium sulfite chemically reacts with the surface of galena and that hydrogen bonds are the main driving force of the adsorption of sodium lignosulfonate onto the surface of galena. The use of a combination of sodium sulfite and sodium lignosulfonate increases their adsorption onto the surface of fine-grained galena.