A Green and Efficient Strategy: Unraveling the Role of Glutathione in the Flotation Separation of Galena and Talc

Talc, as a common gangue mineral, is frequently found in many nonferrous metal ores (such as galena, molybdenite, etc.). Due to its natural hydrophobicity and layered structure properties that are similar to those of nonferrous metal sulfide minerals, efficient flotation separation is often difficult to achieve. To address this challenge, this study introduces for the first time the use of reduced glutathione (GSH) for the flotation separation of galena and talc. Microflotation tests demonstrate that at natural pH (≈6.7), GSH selectively acts on and depresses galena, gradually reducing its floatability, while only weakly influencing the floatability of talc. This results in a significant difference in floatability between the two minerals. Subsequent surface characterization and analyses further corroborate the microflotation findings. Contact angle measurements show that GSH reduces the contact angle of galena surfaces, enhancing their hydrophilicity, whereas the contact angle of talc remains largely unchanged, retaining its strong hydrophobicity. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) observations reveals that GSH treatment leads to the formation of dense, white, spot-like structures on the galena surface, while no noticeable changes are detected on the talc surface. Combined analysis of Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) indicates that GSH undergoes specific chemical adsorption on the galena surface. The -SH, -COOH, and C-N/N-H bonds in the molecule coordinate with Pb²⁺ ions on the galena surface, forming stable surface complexes that significantly enhance the mineral's hydrophilicity. In contrast, no discernible changes in characteristic peaks or chemical states were detected for talc, indicating minimal interaction with GSH. This selective difference in surface behavior toward the two minerals is pivotal for achieving efficient flotation separation of galena and talc.