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

Abstract

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.