Flotation separation of xenotime from silicates using 2-hydroxy-3-naphthyl hydroxamic acid collector and its adsorption mechanism: experimental and first-principles calculations

Heavy rare earth elements (HREEs) have extensive applications in critical industries. Xenotime (YPO 4 ) is an important phosphatic mineral rich in HREEs. The application of 2-hydroxy-3-naphthyl hydroxamic acid (NHA) as a collector in the flotation of xenotime has rarely been been explored previously. This study reveals the effect of NHA on the flotation behavior and adsorption mechanism of xenotime. The high-grade rare earth concentrate with significant recovery is achieved at the optimized flotation conditions. Techniques such as Fourier transform-infrared spectra (FTIR), X-ray photoelectron spectroscopy (XPS), and first-principles calculations were employed to clarify the adsorption mechanism of NHA on xenotime. These studies disclose that chemical adsorption occurs through the interaction between N-bonded and carbonyl O atoms, creating a bidentate bond with an Y 3+ ion on the xenotime surface. These findings underscore the potential of NHA for selective flotation of xenotime, providing valuable insight into xenotime processing.