Session: Lanthanide and Actinide Chemistry:

The rare earth metal dysprosium (Dy) is designated as a critical material by the United States due to its importance for clean energy technology and the scarcity of domestic supply. Harvesting Dy from end-of-life Neodymium-Iron-Boron (Nd-Fe-B) magnets is one potential route for diversifying and fortifying Dy supply. However, efforts in metal processing and recycling often prioritize efficiency over principles of green chemistry. The proposed Nd-Fe-B recycling method offers an alternative to traditionally employed solvent extraction and seeks to avoid the use of the caustic mineral acids, phosphonium based extractants, and volatile organic compounds (VOCs) commonly used in Dy extraction. First, a patented, room temperature, acid-free leaching process was used to isolate the rare earth elements of the Nd-Fe-B magnet in the form of oxalates. Subsequently, the chemical separation of rare earth oxalates (CSEREOX) approach combined with microwave-assisted temperature control was applied. Compared to light rare earths oxalates, Dy oxalate exhibited a higher solubility in the organic base, 1-methylimidazole, allowing for Dy extraction from a rare earth oxalate mixture through selective solubilization. This environmentally benign process achieved >65% Dy extraction efficiency with only 12% co-extraction of Nd.

Denis Prodius

Appearances