Mechanistic Interpretation of Thioglycolic Acid as a Depressant in the Differential Flotation of Molybdenite from Chalcopyrite

Abstract

This study explores the potential of thioglycolic acid (TGA) as an eco-friendly depressant for chalcopyrite in the differential flotation of molybdenite from chalcopyrite. Laboratory flotation experiments and molecular dynamics (MD) simulations were employed to evaluate TGA's effectiveness compared to sodium sulfide. The experiments demonstrated that TGA significantly enhanced chalcopyrite depression, achieving optimal molybdenite recovery (90.43%) and chalcopyrite depression (83.63%) under specific conditions: 2 kg/t TGA dosage, pH 11.5, and 28% solids. Statistical analysis highlighted TGA dosage and pH as the most influential parameters. However, excessive TGA concentrations led to froth destabilization, reducing separation efficiency. MD simulations confirmed TGA's stronger adsorption and hydrophilic modification of chalcopyrite surfaces, reducing its floatability while preserving molybdenite selectivity. The simulations revealed that TGA increases surface hydrophilicity by promoting denser water molecule packing and forming a robust adsorbed layer that prevents collector attachment. These findings were corroborated by surface energy and solvent-accessible surface area (SASA) analyses, which demonstrated TGA’s stronger interaction with chalcopyrite compared to sodium sulfide. The dual-scale approach of this study bridges the gap between laboratory-scale experimentation and molecular-level understanding, offering a comprehensive evaluation of TGA’s potential as a green depressant in mineral processing. By reducing reliance on toxic depressants like sodium sulfide, TGA represents a sustainable alternative for the selective flotation of molybdenite.