A Non-Toxic Depressant for Galena in Differential Flotation of Cu-Pb Sulfides
Tannic acid, a natural polymer extracts from trees, was found to selectively depress galena while chalcopyrite was floated by xanthate. Micro-flotation studies, adsorption and Fourier transform infrared spectroscopy have been employed to investigate the mechanism. Micro-flotation studies shown that tannic acid can effectively depress galena while depress chalcopyrite weakly in the entire pH range. The adsorption results shown that the tannic acid adsorbed on chalcopyrite and galena surface influenced by the pH value, the higher the pH, the less of adsorption density. Tannic acid adsorb on galena through complexation with the lead ions, not with hydroxyl complex in the galena surface. Fourier transform infrared spectroscopy revealed that tannic acid interacted with lead ions by the hydroxyl groups on the phenol group. Tannic acid may be replace the hazardous inorganic depressants such as cyanide, dichromate and sulfur dioxide used in differential Cu-Pb sulfide separation.