The global demand for rare earth elements has increased along with the emergence of new technologies. A major mineral source of rare earth elements is bastnäsite, a fluorocarbonate mineral rich in Y, La, and Ce. Separation from the surrounding ore is achieved via froth flotation. However, current schemes utilize fatty acid collectors, which exhibit low selectivity for bastnäsite. Without an efficient method of separation, the economic viability of rare earth mining in the United States is limited.<br/>The aim of this work is to design a reagent that will adsorb specifically to bastnäsite in the presence of associated ore minerals. Alkyl hydroxamic acid has been identified as a potential improvement, but its selectivity and mechanism of adsorption are not well characterized. Further insight into the interaction of hydroxamic acids at the mineral-water interface is required to strategically design more selective reagents. In this work, we have developed a method for quantitatively evaluating collector selectivity for bastnäsite over calcite, a major gangue mineral, using several hydroxamic acid collectors in varying solution conditions. Adsorption was measured experimentally using solution depletion and ATR-FTIR characterization and fit to isotherm models. We compared these results with computational geochemical models of the solution and interface. We found that adsorption of the surfactant onto both bastnäsite and calcite is dependent on solution composition. These findings illustrate the importance of considering solution equilibria in experimental and simulation work used to design new collector molecules.

Solution chemistry of hydroxamic acid adsorption onto bastnäsite and calcite

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.