Separation of lithium from sodium in chloride solutions using SSX systems with LIX 54 and Cyanex 923

Abstract

A novel synergistic solvent extraction (SSX) system consisting of LIX 54 and Cyanex 923 in ShellSol D70 to recover lithium and separate it from sodium in chloride solutions has been developed. With the SSX system, over 97% of lithium was extracted at pH11 from a synthetic solution with almost no extraction of sodium in a single contact, resulting in a separation factor of lithium over sodium of 1560, indicating very good separation. The co-extracted sodium could be readily scrubbed from the loaded organic solution using water. Lithium was readily stripped with acidic solution and complete strip was achieved at an equilibrium pH of 3.5. The lithium extraction McCabe Thiele diagram showed that three theoretical stages could be used to completely extract lithium from the synthetic solution using an aqueous/organic (A/O) ratio of 2:1. Based on the lithium strip McCabe Thiele diagram, two theoretical stages are required with a 0.5M HCl strip solution at an A/O ratio of 1:3. The lithium extraction and strip kinetics were very fast. The extracted lithium species was found to be LiAB, where A and B represents the deprotonated LIX 54 (A) and Cyanex 923, respectively.