Numerical simulation of Lithium extraction from salt Lake brines through force environment modulation in microfluidic channels with ion concentration polarization

Abstract

Force-environment-modulated microfluidic devices possess significant potential for the efficient lithium extraction from salt-lake brines. This paper proposes a novel force-environment-modulated system for the simultaneous Li+ concentration and Mg2+ removal from high Mg2+/Li+ ratio (MLR) brines. In this system, multiple parallel barriers are positioned within a microchannel to regulate the flow of fluids. The differentiated horizontal fluid flow velocities implement a localized region of force balance for Li+ exclusively, enabling Li+ to be collected at the upward outlet while continuously expelling other ions. In addition, a vertical barrier in front of the balance region will increase Li+ enrichment and decrease it on the opposing side, thus further enhancing the concentration of Li+ and the removal of Mg2+ to a greater extent. The results obtained through two-dimensional simulation using a diluted model brine demonstrate that this system has the capability to concentrate Li+ by 4.5 times and achieve an 89% removal of Mg2+, where the MLR decrease to 3.45, and the separation factor reaches 6.17. The modulation of force environments for differently charged particles provides a new approach to achieve their simultaneous concentration and separation.