Numerical Simulation of Continuous Extraction of Li from High Mg/Li Ratio Brines Based on Free Flow Ion Concentration Polarization Microfluidic System.

Ion concentration polarization (ICP) is a promising mechanism for concentrating and/or separating charged molecules. This work simulates the extraction of Li ions in a diluted high Mg/Li ratio salt lake brines based on free flow ICP focusing (FF-ICPF). The model solution of diluted brine continuously flows through the system with Li slightly concentrated and Mg significantly removed by ICP driven by external pressure and perpendicular electric field. In a typical case, our results showed that this system could focus Li concentration by ~1.28 times while decreasing the Mg/Li ratio by about 85% (from 40 to 5.85). Although Li and Mg ions are not separated as an end product, which is preferably required by the lithium industry, this method is capable of decreasing the Mg/Li ratio significantly and has great potential as a preprocessing technology for lithium extraction from salt lake brines.