Chloride ion enhanced lead-benzohydroxamic acid flotation of cassiterite through synergistic surface adsorption mechanism

• Elucidated the synergistic activation mechanism of PbCl + complex ions on the mineral surface. • Quantitatively explained the influence of activation sites on collector adsorption configuration and stability from a molecular scale. • Proposed a novel multi-level interfacial regulation strategy of “ion-ion-molecule” for the flotation of oxide minerals. This study systematically investigates a novel approach utilizing the synergistic effect of lead ions and chloride ions to enhance the flotation performance of cassiterite. Through solution chemistry analysis and micro-flotation tests, that low concentrations of chloride ions can significantly improve both the recovery and selectivity of cassiterite in the lead-benzo hydroxamic acid (BHA) system across a alkaline pH range. Characterization techniques including Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS), and X-ray Photoelectron Spectroscopy (XPS) consistently verified that chloride ions co-adsorb with lead ions on the cassiterite surface, primarily forming PbCl + complexes. The enhanced characteristic peaks of BHA in FTIR spectra and the increased adsorption capacity following chloride ion addition demonstrate that these complexes serve as more effective active sites, promoting the chemisorption of BHA. First-principles density functional theory (DFT) calculations provided further quantitative evidence, revealing that the adsorption energy of BHA on the PbCl + -activated cassiterite surface is significantly lower than that on the surface activated solely by Pb 2+ , confirming that the former induces a stronger and more stable adsorption configuration. This research provides an important theoretical foundation and profound mechanistic insights for optimizing reagent schemes in the industrial flotation of cassiterite and other oxide minerals.