Flotation of Bastnaesite by Mixed Collectors and Adsorption Mechanism

Bastnaesite, as one of the most important sources of rare earth elements, are typically separated through flotation. However, the complex association and fine particle size of bastnaesite make it challenging to achieve high flotation recovery and grade. In this study, mixed collectors composed of benzohydroxamic acid (BHA) and salicyhydroxamic acid (SHA) has been developed for the flotation of bastnaesite. Results show that BHA has better collection performance while SHA show better selectivity in the flotation separation of calcite and dolomite. The combination of BHA and SHA in the flotation turn out that the recovery and grade of bastnaesite are simultaneous promoted compared to single collector. Adsorption experiments indicate that bastnaesite has larger adsorption capacity to BHA, while SHA are more selective adsorbed on bastnaesite rather than calcite and dolomite. Zeta potential measurements confirm the stronger adsorption of mixed collector onto the bastnaesite surface compare to single collectors, which agree well with the flotation results. The FTIR analyses show that the mixed collector undergoes a chemical reaction on the bastnaesite surface, facilitating chelation between the collector and bastnaesite. The XPS analyses verified that the newly formed bonds are Ce-O bonds between the collectors and bastnaesite. Overall, this study developed a kind of mixed collector for bastnaesite flotation, the synergistic effect and co-adsorption of BHA and SHA on bastnaesite surface have been demonstrated, which provide new approach to improve the flotation recovery and grade of bastnaesite.