Liquid-liquid extraction and chromatography process routes for the purification of lithium
Since several years, the lithium market is characterized by high growth rates especially due to the increasing demand for lithium-ion batteries. Therefore, the primary production is currently expanded and there is a growing interest in recycling. However, because of the chemical properties of lithium, many production processes lack efficient processes for the separation, concentration and purification of lithium. This article reviews the current use of liquid-liquid extraction (LLE) and chromatography in lithium production as well as research. Currently, the industrial application of LLE and chromatography in lithium purification is limited to the extraction of impurities and co-products. Extraction of lithium is only used as concentration step in few processes before lithium precipitation. In research and development, a wide variety of extractants and resins is investigated. In LLE, chelating extractants like crown ethers and calixarene and synergistic systems show the greatest potential. In the chromatographic separation the main focus of research lies upon cation exchange media, especially media with sulfonated ligands.However, most research is still in early development. Therefore, extensive research is needed to enable the industrial use of optimized LLE and chromatography processes in lithium production.