Electrodialytic concentrating lithium salt from primary resource

Abstract Lithium and its related products are important materials in modern society. A large amount of energy is consumed for the extracting or concentrating lithium salts from primary resources. In this study, electrodialysis (ED) was introduced to concentrate Li 2 SO 4 solution. Effects of ion exchange membrane type, applied voltage drop across the ED stack, and especially the operating mode were investigated. Results indicated that Neosepta AMX/CMX membranes were more preferable than FKS/FAS and CJMC/MA membranes for lithium salt concentrating at the voltage drop of 6 V. Additionally, it's found that the volume ratio of 1:3 was optimal choice for two-stage ED. The final Li 2 SO 4 concentration could reach as high as 17.4 wt% with two-stage electrodialysis (V c :V d  = 1:3); while the special energy demand could be as low as 30.9 kWh/m 3 in one-stage ED when the operate voltage was 4 V. From the viewpoint of energy consumption, “a high volume ratio concentrating” with volume ratio of 1:10 was more competitive than “two-stage concentrating”. Naturally, electrodialysis is not only energy saving but also high-effective for lithium extraction and concentrating.