Continuous microdroplet countercurrent extraction for lithium recovery from high Mg/Li brines

Lithium's critical role in energy storage drives demand for efficient recovery from high Mg/Li mass ratio brines. Traditional liquid-liquid extraction techniques face limitations in mass transfer and operational performance. In this study, we propose a continuous countercurrent microdroplet-based extractor integrating a T-junction microdisperser with a millimeter-scale column, utilizing a TCPP/NaBPh 4 /2-octanone system for selective Li + recovery. Systematic investigation of microdroplet dynamics revealed stabilized diameters of 145 μm (with a 20% column holdup) during extraction and 160 μm (with a 25% column holdup) during stripping. Optimized operation achieved >99% Li extraction and > 95% stripping efficiency, while reducing Mg/Li mass ratio from 274 to 0.44 in the organic phase. Remarkably, within a column height of 25 cm, the number of theoretical stages achieved for the extraction and stripping were 2.13 and 2.29, respectively. The volumetric mass transfer coefficient reached 0.119 s −1 , representing an improvement of one to two orders of magnitude compared to conventional devices. This microreactor approach demonstrates that precise microdroplet size control enhances mass transfer intensification, offering an efficient solution for strategic lithium recovery from high Mg/Li brines.