Potential of Ligand-Promoted Dissolution at Mild pH for the Selective Recovery of Rare Earth Elements in Bauxite Residues

In a context of overexploitation natural resources, circular economy and particularly the extraction resources from secondary sources are essential to sustain number key technologies including renewable energies. Among sources, bauxite residue contains critical elements rare earth (REEs) (712 mg/kg). We investigated use soft selective dissolution protocols at mild pH values (2–6) as an alternative pyro- hydrometallurgy for recovery REEs through ligand-promoted dissolution. This approach depends on detailed characterization waste speciation targeted elements. assessed using low-molecular-weight organic acids their conjugate bases. Citric acid/citrate showed satisfactory (up 50% light REEs) up nearly 5, while tartaric acid/tartrate best selectivity (enrichment factor 21.5 compared Fe, Al, Ti). Almost no heavy were dissolved in any conditions tested, probably due high chemical stability bearing phases. Indeed, found discrete phosphate particles.