Electrodialytic concentrating lithium salt from primary resource

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 Li2SO4 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 Li2SO4 concentration could reach as high as 17.4 wt% with two-stage electrodialysis (Vc:Vd = 1:3); while the special energy demand could be as low as 30.9 kWh/m3 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.