Effect of Iron(III) ions on rutile flotation: Surface properties and adsorption mechanism

Various studies have shown that the presence of metal ions in the slurry can significantly impact flotation . However, it was still uncertain how iron, a typical metal ion, affected rutile flotation. Micro-flotation experiments, x-ray photoelectron spectroscopy , icp-oes, solution chemistry calculation, zeta potential and contact angle test were used to explore the effect of iron ions on the surface properties and floatability of rutile in this investigation. Micro-flotation results showed that iron ions not only substantially increased the rutile flotation recovery from 42.27 % to 75.69 % at pH = 4, but also converted the optimal pH of flotation from a point (pH = 4) to a platform (pH = 4–8). Solution chemistry calculations indicated that iron ions could form complexes with hydroxyl to produce FeOH 2+ , which reacted with benzohydroxamic acid (BHA) to create [Fe(C 7 H 6 NO 2 ) 2 ] + at pH=4–7. The analysis conducted through X-ray photoelectron spectroscopy , coupled with the results obtained from contact angle measurements, revealed that the complex [Fe(C 7 H 6 NO 2 ) 2 ] + had the capability to engage with Ti-OH groups, improving the hydrophobicity of rutile surface. Zeta potential analysis results further illustrated that Fe 3+ /BHA complexes reinforce the adsorption of BHA and iron ions onto rutile surface by the formation of [Fe(C 7 H 6 NO 2 ) 2 ] + . In addition, the O1s peak fitting results and ICP-OES analysis results proved that at the same pH, 60 mg/L was the optimal concentration for iron ion activation, which may be limited by Saturated adsorption capacity of [Fe(C 7 H 6 NO 2 ) 2 ] + .