Surface modification and flotation improvement of ilmenite by using sodium hypochlorite as oxidant and activator

Abstract

In this study, we have developed a novel method for ilmenite activation. Sodium hypochlorite was used as an oxidant and surface modifier to promote ilmenite flotation. And it has successfully been performed valence transitions of iron atoms on the ilmenite surface, thereby enhancing the action activity between the surface sites of ilmenite and sodium oleate. Eventually the surface Fe3+ content increased from 42.15 to 63.79%. Oxidation by sodium hypochlorite increased the amount of Fe3+ on the ilmenite surface by 21.64% and improved the ilmenite recovery to 95%, while the maximum recovery of ilmenite without sodium hypochlorite addition was only 85%. The activation mechanism of ilmenite by sodium hypochlorite was studied by batch flotation, Zeta potential measurement, X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and reaction thermodynamic analysis. The results of potential measurement show that sodium hypochlorite made the Zeta potentials of ilmenite–sodium oleate system more negative mainly due to the enhanced adsorption effect between them. FTIR results indicate that more prominent absorption peak of iron oleate appeared in the FTIR spectrum of ilmenite treated with sodium oleate after sodium hypochlorite oxidation. XPS analyses suggest that more Fe2+ on ilmenite surface supplied electrons to the oxidant and formed more Fe3+. Reaction thermodynamic analyses also show that compared with Fe2+, Fe3+ was more likely to interact with oleate ions and formed more stable species. In summary, sodium hypochlorite can activate ilmenite and improve its flotation.

Keywords

• Ilmenite
• Sodium hypochlorite
• Oxidation
• Valence transition
• Flotation