Bastnaesite flotation chemistry issues associated with alkyl phosphate collectors

The hydrophobicity, selectivity, and adsorption state in bastnaesite flotation using alkyl phosphates were examined by contact angle and zeta potential measurements, microflotation and microcalorimetry experiments, as well as density functional theory calculations and molecular dynamics simulations. The contact angle and microflotation results show that bastnaesite flotation with alkyl phosphates (lauryl phosphate and 2-ethylhexyl phosphate) is accomplished at a remarkably lower collector concentration. Selective flotation of bastnaesite from calcite with 2-ethylhexyl phosphate increased the bastnaesite grade from 52% to 95% without sacrificing recovery when compared to lauryl phosphate. As expected, the results from density functional theory calculations, together with the microcalorimetry and molecular dynamics simulation results, suggest that the hydrophobic surface state is due to a chemisorbed monolayer of the alkyl phosphate and that the lower reactivity of 2-ethylhexyl phosphate accounts for higher selectivity when compared to results for lauryl phosphate.