Recovery and Selective Electrochemical Separation of Rare Earth Elements

The analysis of rare earth elements in materials such as phosphogypsum, a by-product of phosphoric acid production, plays an important role in nuclear safeguards, forensics, and environmental applications. In many of these applications, where radiometric detection of fission products is desired, it is critical to separate individual target rare earths into pure streams to enable accurate quantification. Current analytical-scale rare earth element separation technologies are based on ion exchange chromatography are slow and ineffective. The similar chemical properties of the rare earth elements present fundamental difficulties to realizing improved separations processes through chemical means alone. An electrochemical platform for the recovery and analytical separation of individual rare earth elements from phosphogypsum feedstocks will be demonstrated. In this process, rare earth elements will be extracted from phosphogypsum feedstocks using task specific extractants. These rare earth elements will then be selectively separated into an aqueous eluent stream using an electrochemically-controlled process. A process for the extraction of rare earth elements from phosphogypsum samples using taskspecific extractants will be developed and optimized to maximize extraction efficiency and minimize process time. Separation of extracted rare earth elements will then be demonstrated in electrochemical cells which control rare earth element distributions between phases. New electrolyte compositions for this process will be characterized and practical electrochemical cells will be designed to process samples on the 1-100 mL scale in minutes. Technoeconomic analyses of the developed process will be carried out and commercial prototype designs prepared for deployable systems (i.e., separations kits) which could be integrated into existing analytical workflows. This project will demonstrate a new approach to rare earth element separations which can be incorporated into a wide variety of rare earth element analysis workflows. Phase II work will focus on the design and production of prototype rare earth element separation kits which can be directly marketed to relevant industrial, academic, and government laboratories across the United States.