Ionic Liquids for the Processing of Rare Earth Elements

Ionic Liquids are room temperature organic molten salts that are being investigated for various metallurgical processing applications. Specifically, the application of ionic liquids (ILs) in the extraction, refining, separation, and reduction of the rare earth elements provides many opportunities for reducing the processing economic and environmental costs. The primary fields of research involve the replacement of organic diluents and extractants in solvent extraction, their utilization in flotation, and their application in electrometallurgy. Additionally, ILs are being investigated as a replacement for water, transitioning from hydrometallurgy to solvometallurgy. Advantages of ILs include their low vapor pressure, high thermal stability, and significant variability in coordination ability. This later advantage allows researchers to design task-specific ILs with targeted characteristics. In electrometallurgy, ILs allow for the electrodeposition of highly water-reactive metals such as the rare earth elements and offer a potential alternative to high-temperature molten salt electrolysis and metallothermic reduction processes.