Effect of CuSO4 activation on lepidolite flotation performance using sodium oleate as a collector

Lepidolite is an essential mineral for lithium extraction; however, its weak flotability necessitates improving flotation efficiency. This study investigates the effect of Cu2+ on the flotation performance and surface properties of lepidolite, using sodium oleate (NaOL) as a collector and CuSO4 as an activator. Micro-flotation experiments demonstrate that at a pulp pH of 8, with CuSO4 and NaOL concentrations of 100 mg/L and 80 mg/L, respectively, lepidolite recovery significantly increases to 85.16 %. Solution chemistry calculations and surface analysis techniques elucidate the activation mechanism. Cu2+ and Cu(OH)+ are identified as the dominant species in the solution. Cu2+ chemisorb onto the lepidolite surface via chemical interactions, not only creating new adsorption sites for NaOL but also activating Al-O sites, thereby enhancing NaOL adsorption and facilitating stable complex formation. Adsorption capacity measurements and time-of-flight secondary ion mass spectrometry (ToF-SIMS) confirm the synergistic adsorption of Cu2+ and NaOL. Furthermore, molecular dynamics simulations demonstrate that CuSO4 reinforced NaOL adsorption, effectively reducing surface water concentration and enhancing lepidolite hydrophobicity, optimizing mineralization at the gas-solid interface. This study provides a molecular-level understanding of Cu2+ activation, offering theoretical insights for interfacial regulation in lepidolite flotation.