Development of Ligand-Associated Solid-Liquid Extraction Media System for Separation of High Purity Individual Rare Earth Elements from Coal-based Resources

Commercial sources of rare earth elements include bastnaesite (La, Ce)FCO3, monazite, (Ce, La, Y, Th)PO4, and xenotime, YPO4. However, the processing of these materials to extract and recover the rare earth elements is challenging and very process intensive. However, there are numerous domestic sources of rare earth elements, from waste materials such as coal fly ash, which could be extracted beneficially. There are several physical and chemical methods typically employed to separate the materials of interest from gangue material, which usually leads to the production of a mixed rare earth element concentrate. The mixed rare earth concentrate is then subjected to an entirely separate process to isolate the individual rare earth elements into high purity materials for use in commercial applications. This team will build on its past successes with ligand-associated separation media to develop a new class of sorption media, and a process to separate individual rare earth elements, resulting in individual high purity rare earth oxide (REO) powders. This new class of sorption media will combine two classes of ligands: 1) glycolipids and 2) DTPA-analogs, synthesized in-house for fundamental proof-of-concept testing for the proposed novel process to concentrate REEs from coal leachates. Our process will also allow for the separation of mixed light REEs from the heavy REEs, along with separation of these concentrates into individually separated REE materials. This team anticipates that Phase I will result in REO purity >90% with less than 10 processing steps (as opposed to 100’s to 1000’s of steps for current liquid-liquid separations). If successful in Phase II and beyond, we anticipate that our media and our novel process will result in the economic recovery of rare earth elements from coal refuse and coal combustion residuals, with a potential cost savings of over 20% relative to current technologies. This technology will result in an environmentally-friendly process having lower costs than are currently provided by state-of-the art liquid-liquid separations, and it will require significantly less hazardous waste disposal. Our commercialization strategy will enable this team to work with its industry partners to demonstrate the large scale deployment of this technology, which will ensure a domestic supply of critical REOs for industrial or military applications.