Interfacial regulation mechanism of flaxseed gum in the selective depression of galena during chalcopyrite flotation

The similar physicochemical properties and floatability of chalcopyrite and galena render their efficient flotation separation challenging. To develop a green and efficient depressant for galena, this study introduced flaxseed gum (FG) into the chalcopyrite-galena flotation separation system, with sodium butyl xanthate (SBX) as the collector, to systematically investigate the selective depression performance and interfacial interaction mechanism of FG. Flotation results indicated that under the conditions of pH 9.50, an FG dosage of 7 mg/L, and an SBX dosage of 5 mg/L, the galena recovery decreased from 88.92 % to 8.18 %, whereas the chalcopyrite recovery was almost unaffected. Contact angle, zeta potential, and EDLVO calculations demonstrated that FG significantly enhanced the surface hydrophilicity of galena, primarily by modulating hydrophobic interactions to weaken the particle-bubble adhesion. The total attractive interaction energy between particles and bubbles was reduced by 90.8 % (at H = 10 nm), thereby weakening the stable attachment of galena particles. Surface characterization, adsorption amount measurements, and molecular simulation results indicate that FG preferentially undergoes chemisorption or complexation with Pb sites on the galena surface through oxygen-containing functional groups such as –COO − , forming a hydrophilic macromolecular adsorption layer that hinders the subsequent adsorption of SBX. In contrast, the interaction of FG with the chalcopyrite surface is weaker, allowing chalcopyrite to maintain its floatability. This study provides a novel natural polymeric depressant for the green and efficient flotation separation of chalcopyrite from galena.