Surface Mechanism of Fe³⁺ Ions on the Improvement of Fine Monazite Flotation With Octyl Hydroxamate as the Collector

Froth flotation of fine minerals has always been an important research direction in terms of theory and practice. In this paper, the effect and mechanism of Fe³⁺ on improving surface hydrophobicity and flotation of fine monazite using sodium octyl hydroxamate (SOH) as a collector were investigated through a series of laboratory tests and detection measurements including microflotation, fluorescence spectrum, zeta potential, and X-ray photoelectron spectroscopy (XPS). Flotation tests have shown that fine monazite particles (-26 + 15 μm) cannot be floated well with the SOH collector compared to the coarse fraction (-74 + 38 μm). However, adding a small amount of Fe³⁺ to the pulp before SOH can significantly improve the flotation of fine monazite. This is because the addition of Fe³⁺ promotes the adsorption of SOH and greatly improves the hydrophobicity of the monazite surface. This can result in the formation of a more uniform and dense hydrophobic adsorption layer, as shown by the fluorescence spectrum and zeta potential results. From the XPS results, Fe³⁺ reacts with surface O atoms on the surface of monazite to form a monazite-O_surf-Fe group that acts as a new additional active site for SOH adsorption. A schematic model was also proposed to explain the mechanism of Fe³⁺ for improving surface hydrophobicity and flotation of fine monazite using octyl hydroxamate as a collector. The innovative point of this study is using a simple reagent scheme to float fine mineral particles rather than traditional complex processes.