The application of KMnO4 in reverse flotation separation of chalcopyrite and talc and its selective depression mechanism

Talc exhibits excellent floatability and, as a major silicate gangue mineral associated with chalcopyrite, significantly obstructs the purification and smelting of chalcopyrite. This study investigates the reverse flotation separation of chalcopyrite and talc using KMnO 4 as a depressant and DDA (dodecylamine) as a collector within a reverse flotation system. Single mineral flotation experiments show that after adding KMnO 4 , the recovery of chalcopyrite in 38–74 μm is only 6.86 %, whereas the recovery of talc in 45–106 μm and 25–45 μm are 93.47 % and 89.25 %, respectively. Further experiments with artificially mixed ores demonstrate that KMnO 4 effectively achieves the separation of chalcopyrite and talc. The depression mechanism of KMnO 4 on chalcopyrite and talc was analyzed using Zeta potential, contact angle measurement, AFM (atomic force microscopy), FTIR (Fourier transform infrared spectroscopy), XPS (X-ray photoelectron spectroscopy), and DFT (density functional theory) calculations. Mechanistic analysis indicates that in an alkaline environment, chalcopyrite can undergo a redox reaction with KMnO 4 , forming hydrophilic hydroxide species (Cu(OH) 2 , Fe(OH) 3 ) on the chalcopyrite surface, which depresses chalcopyrite flotation. In contrast, the surface properties of talc are relatively stable and difficult to react with KMnO 4 , which cannot depress the flotation of talc. Therefore, KMnO 4 can be used as an efficient and selective depressant for the reverse flotation separation of chalcopyrite and talc.