This technology is a process for recovering lithium from lithium-containing aqueous solutions. By placing a nanofiltration step before the membrane distillation step, it selectively removes divalent ions such as Ca²⁺ and Mg²⁺—the primary causes of membrane performance degradation—while concentrating monovalent ions, including lithium.
In the process of concentrating lithium-containing brine via membrane distillation, divalent ions like calcium and magnesium often form crystals, such as CaSO₄, on the membrane surface. These crystals cause wetting, which leads to a sharp decline in distillation performance or complete process failure.
This technology utilizes a nanofiltration membrane with a divalent ion rejection rate of over 30%, a monovalent ion rejection rate of under 10%, and a permeate flux of 20–50 Lm⁻²h⁻¹ placed upstream of the distillation module to pretreat the brine. By inhibiting crystal formation within the distillation module, it enables the stable production of high-concentration lithium solutions exceeding 1,000–1,500 ppm. Applicable to facilities processing low-concentration lithium resources such as salt lake brine, geothermal brine, and seawater desalination concentrate, it provides a pathway for continuous lithium production with extended membrane cleaning cycles, eliminating the need for large-scale evaporation ponds.
WO2021-101129A1
