Depressing molybdenite using calcium lignosulfonate in Cu-Mo flotation separation: Interaction and desorption insights

This study investigated the potential mechanisms by which lignosulfonate selectively depresses the flotation of fine molybdenite during Cu–Mo flotation separation using ethyl potassium xanthate as a collector. The flotation tests confirmed that molybdenite was significantly depressed by calcium lignosulfonate, whereas chalcopyrite flotation was only slightly affected. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were employed to explore the distinct interaction of lignosulfonates with the mineral surfaces: chelation/complexation occurred between the deprotonated oxygen-contained groups in calcium lignosulfonate with the exposed metal sites on the surface of chalcopyrite, whereas the hydrophobic interaction between calcium lignosulfonate and molybdenite was the main driving force of adsorption. Additionally, the adsorption experiments suggested that the calcium lignosulfonate previously adsorbed on chalcopyrite could be removed by treatment with ethyl potassium xanthate while there was a relatively small effect on the calcium lignosulfonate previously adsorbed on the surface of molybdenite. Therefore, depressing molybdenite and floating chalcopyrite achieved by using calcium lignosulfonate as the depressant and ethyl potassium xanthate as the collector.