Developing New Process for Selective Extraction of Rare Earth Elements from Bauxite Residue Based on Functionalized Ionic Liquids
Ionic liquids (IL’s) are versatile solvents consisting solely of ions and can be utilized to dissolve selectively rare earth elements (REE) from bauxite residue. The leaching process that developed is based on the hydrophobic ionic liquid betainium bis(trifluoromethylsulfonyl)imide [Hbet][Tf2N] and other similar ionic liquid derivatives. Leaching bauxite residue with HbetTf2N selectively dissolves REE (>70%) against Fe, Al, Ti and Si generating a solid residue to be utilized in cement or iron industry. Scandium appear to have different leaching behavior from the rest REE with maximum 45% recovery upon leaching, whereas Ca and Na almost totally dissolved. The metals dissolve in HbetTf2N leachate, are stripped with an aqueous acidic solution whereas hydrophobic HbetTf2N is regenerated for reuse. During stripping and upon pH adjustment a preconcentrated Sc solution with less impurities is generated. The proposed IL process provides selectivity, recyclability of the leaching agent and more efficient acid input in the process.
KeywordsBauxite residue Scandium Rare earth Ionic liquids Leaching
The research leading to these results has received funding from the European Community’s Horizon 2020 Programme SCALE (H2020/2014-2020/No. 730105), and the European Community’s Seventh Framework Programme ([FP7/2007‐2013]) under grant agreement n°309373. This publication reflects only the author’s view, exempting the Community from any liability”.
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