| Description |
Bastnaesite is a major mineral resource of importance in the production of rare earth materials. Fatty acids and hydroxamate are typically reported as collectors for bastnaesite flotation. In this research, it was found that lauryl phosphate is an appropriate collector for bastnaesite flotation. Results from contact angle and microflotation experiments for bastnaesite are reported using lauryl phosphate as a collector. Almost 90% bastnaesite flotation recovery is achieved at a low level of 5×10-6 M lauryl phosphate at pH 5.1, when compared to the use of 1×10-4 M octyl hydroxamate at pH 9.3. Furthermore, wetting characteristics and microflotation responses were examined as a function of pH and at different levels of lauryl phosphate adsorption. The wetting characteristics of bastnaesite with the adsorbed collectors under a vertical monolayer of 8.46 μmol/m2 were examined using both contact angle measurements and molecular dynamics simulations (MDS). The adsorption isotherm at low levels of lauryl phosphate adsorption was established, and microcalorimetry results suggested chemical adsorption of lauryl phosphate on bastnaesite. Typically calcite and quartz are associated with bastnaesite as gangue minerals. Results from the contact angle, zeta potential, and microflotation experiments for bastnaesite, calcite, and quartz are reported using lauryl phosphate as a collector. With 90% bastnaesite flotation recovery and less than 5% calcite and quartz flotation recoveries were achieved at 1×10-5 M lauryl phosphate, and the results compared to the iv results of 1×10-4 M octyl hydroxamate. Finally, initial evaluation indicates that the branched chain 2-ethylhexyl phosphate increased the bastnaesite grade from 52% to 95% without sacrificing bastnaesite recovery at a concentration of 3×10-6 M and pH 5.0, when compared to lauryl phosphate. The zeta potential, single mineral microflotation, and molecular dynamics simulation results indicate that lauryl phosphate has stronger adsorption when compared with the 2-ethylhexyl phosphate results. The adsorption difference between bastnaesite and calcite/quartz for 2-ethylhexyl phosphate is greater than for lauryl phosphate. Therefore, it is expected that better selectivity can be achieved with 2-ethylhexyl phosphate. The results of this research will enable us to understand bastnaesite/calcite/quartz flotation chemistry using alkyl phosphate collectors with consideration of chemical structure, solution chemistry, and the hydrophobic surface state. |
