Molecular insights into the temperature-responsive interfacial properties of sodium oleate–based combined collectors for spodumene flotation

Efficient flotation of spodumene at low temperatures remains a major challenge in lithium resource recovery. This study explores the flotation performance and interfacial behavior of combined collectors comprising sodium oleate (NaOL) with dodecyl amine (DDA) or dodecyl trimethylammonium chloride (1231) across temperatures from 5 °C to 35 °C. Flotation results show that collector performance generally declines at lower temperatures, particularly at low concentrations. However, the NaOL/1231 system maintained high spodumene recovery (>80 %) at 5 °C using only half the concentration required by the NaOL/DDA system, highlighting its superior low-temperature adaptability and economic advantage. Surface tension and critical micelle concentration (CMC) analyses indicate that NaOL/1231 has stronger surface activity and forms a more compact and stable interfacial adsorption layer under cold conditions. Molecular dynamics simulations further confirm that the 1231 cation enhances water molecule orientation, disrupts hydrogen bonding, reduces molecular diffusivity, and stabilizes interfacial structure at low temperatures. These findings elucidate how temperature affects flotation behavior and interfacial dynamics, emphasizing the excellent interfacial stability and cold-resistance of the NaOL/1231 system. This work offers both theoretical understanding and practical guidance for designing flotation reagents with enhanced performance in cold-region lithium mineral processing.