Insights from molecular recognition inform rare-earth mineral beneficiation  

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images depict three ligands on bastnäsite-[100] with explicit solvation Bottom: Comparison of a ligand’s methyl orientation angle as measured by SFG spectra and predicted by DFT simulation for a studied ligand
Top: Depiction of three ligands on bastnäsite-[100] with explicit solvation
Bottom: Comparison of a ligand’s methyl orientation angle as measured by SFG spectra and predicted by DFT simulation for a studied ligand

CMI researchers at Oak Ridge National Laboratory conducted the activity for this highlight

Innovation 
A combined theoretical and spectroscopic approach provides unprecedented insight into how hydroxamic acid-based ligands behave at the molecular level as collectors for selective froth flotation in rare earth ore beneficiation.

Achievement

  • Demonstrated strong, selective binding of a novel ligand containing two hydroxamic acid groups on the predominant bastnäsite crystal facet.
  • Provided meaningful insight into molecular recognition of bastnäsite vs calcite with five hydroxamic acid-based collectors and elucidated the role of water molecules.

Significance and impact

  • Over a billion tonnes of minerals are concentrated by flotation each year, but poor understanding stands in the way of reducing losses, waste, and energy consumption.
  • Highly selective collectors for rare earth minerals are key to improved flotation.
  • Explicit solvation is shown to be essential in density functional theory calculations of hydroxaminc acid adsorption mechanisms, leading to improved prediction.
  • Observed molecular recognition behavior can help guide the design of future collectors. 

Hub Target Addressed 
Highly selective separation from complex sources.

https://doi.org/10.1021/acs.langmuir.1c03422