The U.S. Department of Energy (DOE) and National Energy Technology Laboratory (NETL) have prioritized the creation of a domestic supply chain for production of REEs because they are crucial for a variety of economic, energy and defense applications. However, the current supply chain is dominated by other countries. Therefore, a domestic source would insulate the U.S. from any disruptions in global trade of REEs, and America’s coal ash-based resources show promise to become that source.
With NETL support, PSI and the University of Kentucky’s Center for Applied Energy Research (UK CAER) undertook a comprehensive research effort to investigate the REE content including yttrium and scandium (REYSc) of coal-fired power plant ashes. PSI conducted feasibility and technoeconomic studies for recovery of REYSc from the coal ashes and developed the design of a pilot-scale facility to economically produce salable REYSc-rich concentrates and commercially viable co-products from coal ash feedstock using environmentally safe and high-yield physical and chemical enrichment and recovery processes.
During Phase 2 of the project, PSI, Winner Water Services (WWS), and UK CAER constructed both a micro-pilot facility located at PSI (Andover, Massachusetts) and pilot facility located at WWS (Sharon, Pennsylvania) for chemical processing. An existing facility at UK CAER was used for physical processing of coal ash at approximately 0.4 tons per day (tpd). The micro-pilot was used for initial testing as well as troubleshooting for process operation in the larger pilot-scale facility. The pilot located at WWS in Sharon, Pennsylvania, operated at approximately 0.5 tpd ash throughput for chemical processing. The project team successfully produced over 100 grams of REYSc concentrate and delivered a final product with greater than 50% REYSc content on an elemental basis.
REEs, which represent the 15 elements of the lanthanide series plus scandium and yttrium, are essential for high-tech manufacturing and are used to produce high-performance optics and lasers, as well as powerful magnets, superconductors, solar panels and valuable consumers products such as smart phones and computer hard drives.
PSI and WWS are continuing to further optimize their liquid-liquid extraction operations. As new test data are generated, the team will update their techno-economic model, targeting a less than 10 to 12-year return on investment.