The crystal structure of xenotime consists of a variety of heavier rare earth elements that are critical elements necessary for the production of renewable and energy-efficient technologies. Beneficiation of these elements in a froth flotation process depends on the fundamental understanding of the structural and dynamical stability of the mineral surfaces interacting with water and ligands. To this end, we have employed Density Functional Theory (DFT) to examine the stability of (100), (001), (110), and (101) surfaces of Y-xenotime, both in the gas and microsolvated phases. Utilizing the surface energies and the thermodynamic Wullf construction method, we have predicted the most stable surface (100) and the mineral morphology through the thermodynamic Wullf construction method, which are in consistence with those of the naturally occurring crystal structures. Furthermore, we have performed DFT-based molecular dynamics (MD) simulations to examine the water structure and orientation at the (100) -surface and have determined water adsorption kinetics using the newly established Marcus theory of solvent exchange. This theory utilizes a two-dimensional reaction coordinate involving the distance from the interface and the coordination number of a water molecule to determine the adsorption kinetics. We have further investigated water-mediated ligand-binding in MD simulations by considering a hydroxamate ligand interacting with the (100) -surface either in the bidentate or monodentate configurations. This study provides critical information about the ligand-mineral, mineral-water, and water-ligand interactions, which are the fundamental governing factors in the beneficiation process.

Structure and exchange kinetics of water at xenotime mineral interface: An application to beneficiation of rare earth elements

256th National Meeting (2018)

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