Mechanisms for selective flotation separation of chalcopyrite and molybdenite using the novel depressant 2-(carbamimidoylthio)acetic acid: Experimental and DFT study

• A new chalcopyrite depressant 2-(carbamimidoylthio)acetic acid (CAA) was found. • The depression mechanism of CAA on chalcopyrite flotation was explored. • CAA adsorb on chalcopyrite surface forming a stable triple-bond chelate structure. • The -COOH groups attract water molecules and make chalcopyrite surface hydrophilic. Copper and molybdenum, crucial strategic metals with frequent natural co-occurrence, require highly selective depressants for their flotation separation. However, diminishing ore quality and environmental constraints challenge traditional separation approaches. This study introduces novel 2-(carbamimidoylthio) acetic acid (CAA) as a green depressant for chalcopyrite in copper-molybdenum separation. Through integrated experimental analyses (microflotation, contact angle, FT-IR, TOF-SIMS, XPS) and DFT simulations, we reveal CAA's selective depression mechanism. Results demonstrate CAA significantly enhances chalcopyrite surface hydrophilicity through dual mechanisms: stable triple-bond chelate formation via electron donation from N/S atoms to Fe 3+ /Cu + ions, and hydrogen-bond induced water adsorption through acetic acid groups. Crucially, even with the use of a powerful collector, ethyxanthate, CAA maintains high molybdenite recovery (88.76 %) while effectively depressing chalcopyrite (29.12 %). The elucidated structure-function relationship of CAA's functional groups provides theoretical guidance for developing eco-friendly flotation reagents. This advancement addresses critical challenges in processing complex ores, offering environmental and economic benefits through reduced reagent consumption and improved resource utilization efficiency.