Enhancing the flotation of columbite via the synergistic effect of mixed collectors

Columbite, a critical mineral for niobium extraction, achieving efficient collection of columbite in the flotation process remains a significant challenge. Based on the preliminary work, it was found that octyl hydroxamic acid (OHA) and sodium dodecyl sulfonate (SDS) were used as the mixed collector system, which could reduce the cost and improve the recovery of columbite. However, the synergistic adsorption mechanism of OHA/SDS in columbite flotation requires further investigation. Micro-flotation experiments indicate that the OHA/SDS mixed collector, compared to OHA or SDS used individually, significantly improves the flotation recovery of columbite, with an optimal molar ratio of OHA:SDS = 1:4. Adsorption experiments, zeta potential measurements, contact angle assessments, solution chemistry calculations, X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR) analyses demonstrate that the mixed collector exhibits stronger adsorption affinity on the columbite surface compared to single collectors, revealing a distinct synergistic adsorption effect of OHA/SDS. Atomic force microscopy (AFM) tests reveal that the columbite surface treated with the mixed collector shows more distinct spot-like and layered adsorption features, confirming the synergistic adsorption of OHA/SDS on the columbite surface. Molecular dynamics (MD) simulations suggest that OHA molecules intercalate between SDS ions adsorbed on the columbite surface, effectively reducing electrostatic repulsion among SDS ions, thereby enhancing columbite flotation.