Structural and electronic properties of bastnaesite and implications for surface reactions in flotation

The structural and electronic properties of bastnaesite were studied by using the first-principles method based on the density functional theory (DFT). The geometry structure of bastnaesite was first optimized, and then the Mulliken populations, electron density and density of states were calculated and further analyzed in detail. The calculation results reveal that it mainly ruptures along the ionic Ce–O and Ce–F bonds during the cleavage of bastnaesite, leaving ≡Ce+, ≡F– and ≡CO3– dangling bonds exposed on the cleavage surface of bastnaesite. Combined with contact angle measurement, surface complexation theory and XPS analysis, the implications of structural and electronic properties on bastnaesite flotation reactions were studied. The hydration of exposed strong ionic bond on cleavage surface results in hydrophilic surface. According to surface complexation theory, the formed surface groups are ≡CeOH0, ≡CO3H0 and ≡FH0 groups. The investigated metal ions and flotation reagents complex with surface ≡CeOH0 groups, while ≡CO3H0 and ≡FH0 groups are not involved in the complexation. The high activity of Ce atoms facilitates these surface reactions.