Influence of high concentration Zn²⁺ on floatability of sphalerite in acidic system

The influence of high concentration Zn2+ on the floatability of sphalerite in an acidic system was investigated via flotation experiments, zeta potential measurements, contact angle measurements, and X-ray photoelectron spectroscopy. The results indicated that Zn2+ was adsorbed on the sphalerite surface and a Zn-hydroxyl complex was formed at a pH of 4 and a Zn2+ concentration of 4 x10(-2) mol/L. The zeta potential increased and the contact angle decreased from 84.80 degrees to 36.48 degrees, strongly inhibiting the floatability of sphalerite. When S2- or Cu2+ activator was used alone, sphalerite was not activated after Zn2+ was adsorbed, and its contact angle did not change significantly. However, by using a combination of S2- and Cu2+ activators, its floatability was realized after Zn2+ adsorption. This result was attributed to the removal of the Zn-hydroxyl complex on the surface of sphalerite by S2-. After this removal, Cu2+ was adsorbed on the sphalerite surface to form a Cu2S center dot S-0 hydrophobic film.