Ionic Liquid-based Electrowinning for Refining of Rare Earth Oxides/Salts

Rare earth (RE) elements are used in a variety of energy and defense critical technologies, including permanent magnets and rechargeable batteries, but the vast majority of extraction and processing to convert the oxide to metal is done overseas. Coal and coal-based resources represent a significant potential domestic source of REs. Current RE refinement technologies use high temperatures and highly reactive and toxic chemicals. The development of new techniques and processes to refine rare earth oxides and salts to rare earth metals would enable domestic production of REEs and provide a high value product. TDA will use computational techniques to design ionic liquids (IL) that can solvate individual rare earth cations from their oxide and salt forms. The solvated rare earth cations will be reduced to metals using an electrowinning process. In the Phase I effort we will apply our computation methods to a wide range of ionic liquids to identify those that have both a wide electrochemical stability window and which can effectively solvate the RE cations. Select ILs will be purchased or synthesized in-house. We will experimentally demonstrate the solvation and electrowinning processes on a lab scale, and explore basic process parameters such as temperature and time. An engineering analysis will be performed to identify the scale-up and technoeconomic challenges that we will need to address in Phase II. In 2018, the global REE market size was valued at USD 2.8 billion, and was projected to grow at over 10% a year for the next five years. The development of a US-based rare earth refining industry would greatly reduce imports and increase domestic spending.