Separation of Rare Earths by Solvent Extraction with an Undiluted Nitrate Ionic Liquid
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A solvent extraction system based on the ionic liquid tricaprylmethylammonium nitrate, [A336][NO3], has been investigated for separation of mixtures of rare earth elements (REE) at high total REE concentrations (up to 2 M). The chelating agent EDTA was added to the aqueous nitrate feed solution to increase the separation factors (SFs). This improvement of the SFs is based on the fact that [A336][NO3] extracts the light REE (LREE) stronger than the heavy REE (HREE), whereas a chelating agent forms more stable complexes with the HREE than with the LREE. The combination of these two effects makes that the LREE are even more efficiently extracted than in the absence of a chelating agent. The most efficient separation of the LREE La–Nd from the other REE was obtained using a total initial REE concentration of 1 M, an EDTA concentration of 0.2 M, and a total nitrate concentration of 11 M. Stripping of the extracted REE from the ionic liquid phase could be done using water.
KeywordsIonic liquids Hydrometallurgy Lanthanides Rare earths Solvent extraction
The research leading to these results has received funding from the European Community’s Seventh Framework Programme ([FP7/2007–2013]) under Grant Agreement No. 309373 (EUARE). This publication reflects only the authors’ view, exempting the Community from any liability.
- 6.Mikhailichenko AI, Goryacheva EG, Sokolova NP, Aksenova NM, Vdovina LV, Emelyanov AP (1984) Extraction of rare-earth elements from chloride solutions by salts of quaternary ammonium bases. Sov Radiochem 26:25–29Google Scholar
- 12.Bauer DJ, Lindstrom RE (1971) Differential extraction of rare-earth elements in quaternary ammonium compound-chelating agent systems. Bureau of Mines Report of Investigations 7524Google Scholar
- 15.Bauer DJ, Lindstrom RE (1967) Selective extraction and separation of lanthanides with a quaternary ammonium compound. US Patent 3,323,857Google Scholar
- 16.Gaudernack B, Hannestad G, Hundere I (1974) Process for separation of yttrium from lanthanides. US Patent 3,821,352Google Scholar
- 17.Trimble C, Strott D (1972) Yttrium purification process. US Patent 3,640,678Google Scholar
- 18.Vander Hoogerstraete T, Binnemans K (2014) Highly efficient separation of rare earths from nickel and cobalt by solvent extraction with the ionic liquid trihexyl(tetradecyl)phosphonium nitrate: process relevant to the recycling of rare earths from permanent magnets and nickel metal hydride batteries. Green Chem 16:1594–1606. doi: 10.1039/C3GC41577E CrossRefGoogle Scholar
- 24.Larsson K, Binnemans, K (2014) Applying ionic liquid to rare earth separations. In: Proceedings of the 1st European rare earth resources conference (ERES 2014), Milos, Greece, 4–7 September 2014, p 278–290Google Scholar
- 25.ERECON (2015) Strengthening the European rare earths supply-chain: challenges and policy options. In: Kooroshy J, Ties G, Tukker A, Walton A (eds) A report by the European Rare Earths Competency Network (ERECON)Google Scholar
- 26.Reed GC (2011) NI 43-101 technical report, Norra Kärr REE—zirconium deposit. Pincock, Allen and Holt, GrännaGoogle Scholar