1. Problem Statement Current industrial-scale rare earth element separation technologies are based on solvent extraction schemes which produce large amounts of undesirable chemical waste, including the loss of volatile organic solvents and reagents employed in the treatment of feed streams. These concerns have severely limited the development of U.S.-based rare earth element separation facilities. Addressing this issue will require alternative technologies for the extraction and separation of rare earth elements from domestic rare earth-bearing minerals. 2. Overall Approach We propose to overcome the limitations of traditional rare earth element processing schemes by developing new processes which leverage the unique properties of ionic liquids. Ionic liquids are low-melting salts which possess excellent physical and chemical properties uniquely suited to the extraction and processing of valuable species from traditionally intractable feedstocks. Through the work described herein, ionic liquids will be leveraged to extract rare earth elements from mineral feedstocks, separate the resulting mixtures into elementally pure rare earth feed streams, and recover rare earths as solid products. 3. Phase I Work Plan Work will be carried out to demonstrate and optimize processes for the (1) dissolution and extraction of rare earth elements from mineral feedstocks, (2) separation of individual rare earth elements into different product streams, and (3) recovery of solid rare earth products. Additionally, (4) a detailed technoeconomic analysis of the developed process will be carried out and plans for scale-up will be produced. 4. Commercial Application, Benefits, Phase II and Beyond Results from the proposed research project will be used to select the most energetically favorable, environmentally benign, and economically viable process to extract and separate rare earth elements from mineral feedstocks.
