Mechanism of Fe(Ⅲ)-modified silicate in the flotation separation of spodumene and albite: An experimental and theoretical study

As one of the most important minerals for the extraction of lithium metal, spodumene and its associated mineral, albite, share similar physico-chemical properties, making their separation through flotation a challenging task. In this study, spodumene and albite were successfully separated by flotation using Fe(Ⅲ)-modified silicate, and the fundamental mechanisms of this process were investigated. The results of single-minerals and artificially mixed ores flotation showed that Fe(Ⅲ)-modified silicate exhibited a significantly greater inhibitory effect on albite than on spodumene, allowing for the efficient separation of these two minerals. The results of Zeta potential measurements, FTIR and XPS demonstrated that Fe(Ⅲ)-modified silicate adsorbed on the surface of albite and inhibited the physical and chemical adsorption of NaOL at pH = 7, while exerting minimal impact on spodumene. Atomic force microscopy results indicated that the spodumene surface adsorbed a significant amount of NaOL even in the presence of Fe(Ⅲ)-modified silicate and exhibited an increase in surface height and roughness. However, albite surface height and roughness after interacting with both Fe(Ⅲ)-modified silicate and NaOL were similar to those observed when interacting with Fe(Ⅲ)-modified silicate alone. Finally, density functional theory calculations revealed that Fe(Ⅲ)-modified silicate had a stronger adsorption strength on the surface of albite than spodumene. Consequently, the conclusions of this study could provide guidance and reference for the creation of inhibitors for the selective flotation of spodumene and albite.