Ionic Liquids and its Potential as a New Green Solvent for REE Extraction in Philippine Bauxite Residues

Abstract Rare earth elements (REEs) have become necessary for high-technology applications. This has prompted an increase in demand for REE exploration, production, and extraction. Despite its name, REEs are fairly rich in the Earth’s crust. REEs are estimated to have a crustal abundance of 9.2 ppm relative to other elements in our crust. In the Philippines, deposits are found to give adequately high concentrations of REE, ranging from approximately 200 ppm to 600 ppm. Samar bauxite deposits especially had around 500 ppm REE. In line with the planned bauxite production in the Philippines, it is of interest to further uncover ways to maximize its recovery. One of the possible optimizations in its extraction is to utilize its residue. There have been a number of methods to extract REE in bauxite residues. The use of ionic liquids (IL) to recover REE in bauxite offers a possibility of an effective and environmentally safe recovery process. ILs are molten salts that have melting points below 100degC. They exhibit high electrochemical stability, non-flammability, non-volatility, and can be tailored to the desired application. Hence, they have been the topic of study for different research regarding REE extraction in bauxite residues. Herein, the potential of ILs as a green solvent for REE extraction in bauxite is reviewed for future use in the extractive metallurgy of bauxites in the Philippines.