Flotation behavior and mechanism of tannic acid as a depressant on Cu-Mo flotation separation

Abstract

The similar flotation performance of chalcopyrite and molybdenite in the bulk concentrate made their separation a challenge. Therefore, selective depression of them was required. Previous studies had tended to focus on chalcopyrite depression. Tannic acid (TA), a macromolecular organic compound, has been used as a molybdenite depressant to separate chalcopyrite from molybdenite in flotation. Micro-flotation experiments showed that the TA demonstrated a stronger depression for molybdenite. The Cu and Mo recovery of 95.01% and 3.34% was achieved with the TA in mixed mineral flotation, respectively. The UV spectroscopy measurements suggested that TA had a greater adsorption amount on the molybdenite surface. XPS analysis showed that there was chemisorption between iron ions on chalcopyrite and TA and non-chemisorption between molybdenite and TA. The molecular dynamics simulation indicated that the hydrophobic interaction caused TA to be adsorbed on the molybdenite surface. The hydrophobic interaction between TA and the molybdenite surface was more favorable for adsorption than the chemical interaction of TA with the chalcopyrite surface. Additionally, it was confirmed by infrared spectroscopy analysis that TA adsorbed on the chalcopyrite surface would prevent the subsequent adsorption of PBX (potassium n-butyl xanthate), while PBX significantly weakens the adsorption of TA on the chalcopyrite surface.