Surface chemistry investigation of disodium carboxymethyl trithiocarbonate (Orfom D8) in chalcopyrite-molybdenite flotation: depressing behaviour and adsorption mechanism

The selective separation of chalcopyrite and molybdenite presents a critical challenge in copper-molybdenum ores. Conventional inorganic depressants such as sodium hydrosulfide (NaHS), sodium sulfide (Na 2 S), and Nokes reagent (P 2 S 5 + NaOH) are effective but highly toxic, corrosive, and environmentally hazardous. Their instability and tendency to release hydrogen sulfide gas cause serious operational and safety issues. Consequently, there is increasing interest in developing organic depressants that are safer, more stable, and capable of achieving comparable or superior selectivity in Cu–Mo separation. This study investigates the application of disodium carboxymethyl trithiocarbonate (Orfom D8) in selectively depressing chalcopyrite in chalcopyrite–molybdenite flotation. Microflotation experiments were conducted to evaluate the depressant’s selectivity. The interaction mechanisms between Orfom D8 and the mineral surfaces were investigated using zeta potential measurements, Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS).