Novel insights into the influence of ferric ion as a surface modifier to enhance the floatability of specularite

In this study, micro-flotation tests, solution chemistry calculations, zeta potential analysis, XPS analysis and DFT calculations were employed to systematically study the influence of ferric ion as a surface modifier to enhance the floatability of specularite. The micro-flotation results showed that ferric ions could significantly improve the floatability of specularite within a certain concentration range when sodium oleate as a collector. In the solution, Fe(OH)3 was the main component adsorbed on specularite surface. The zeta potential of specularite shifted positively after treatment with ferric ions, which was not only beneficial to the chemisorption of sodium oleate on the specularite surface but also conducive to the electrostatic interaction between the negatively charged collector and the mineral surface. XPS analysis and DFT calculations results showed that O atoms of Fe-OH on specularite surface were the dominant active sites for ferric species adsorption, and the Fe-O-Fe complexes were mainly formed, which greatly increased the number of reactive sites on the specularite surface, and more hydrophobic species were formed on the specularite surface, thus enhancing the floatability of specularite. [Display omitted] •Ferric ions can be used to improve specularite floatability within a certain concentration range.•O atoms of Fe-OH in specularite surface are the dominant active sites for ferric species adsorption.•Fe-O-Fe complexes play an essential role in the process of activating specularite with ferric ions.