Regulation mechanism of selective adsorption-hydration effects in chalcopyrite-molybdenite flotation separation using 2-iminothiazolidin-4-one (ITO) as chalcopyrite depressant: Experimental and DFT studies

The development of environmentally benign depressants with high selectivity remains a critical challenge in sustainable copper-molybdenum flotation separation. To overcome the limitations of conventional toxic reagents (e.g., cyanides and sulfides), this study introduces 2-iminothiazolidin-4-one (ITO) as a novel chalcopyrite depressant. Through integrated experimental characterization and density functional theory (DFT) simulations, we systematically investigated ITO's selective depression mechanism. Micro-flotation experiments confirmed ITO's ability to preferentially suppress chalcopyrite while maintaining molybdenite floatability. Surface analysis via Fourier-transform infrared spectroscopy (FT-IR), time-of-flight secondary ion mass spectrometry (TOF-SIMS), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) demonstrated that the thiazolidine (-N-C S) and imino (=NH) groups coordinate with surface copper/iron (Cu/Fe) ions to form stable chelates on chalcopyrite, exhibiting stronger adsorption stability than ethyl xanthate. In contrast, only weak physical adsorption occurs on molybdenite surfaces. The carbonyl group (C O) was further found to enhance chalcopyrite hydrophilicity through hydrogen-bonding interactions with water molecules, as supported by contact angle measurements. This work establishes a molecular design strategy for green flotation reagents by leveraging functional group synergism, providing fundamental insights into mineral surface reactivity regulation for strategic metal resource recovery.