Résumé
With a predicted world population of over 9 billion people in 2050 and rapid economic growth, the pressure on natural resources is exponentially increasing. It is the case for critical metals, including Rare Earth Elements (REEs), that are the heart of a number of strategic technologies for the environmental transition. In the context of a circular economy, this project aims at extracting REEs from a secondary source: bauxite residue produced from alumina extraction. In particular, this project proposes to develop environmentally sustainable extraction processes based on the use of alternative solvents: deep eutectic solvents (DES). We propose here to investigate leaching mechanisms of REE oxides, hydroxides and carbonates (phosphate REEs were not dissolved in DES), as a model system in deep eutectic solvents. Those mineral forms are suspected to be representative of the speciation of REEs in most primary and secondary sources including bauxite residue.