Production of LiOH·H2O from lithium chloride by electrodialysis and crystallisation

Laboratory bench scale experiments were performed to develop a process for electrodialysis (ED) of LiCl liquor from spodumene leaching and purification to produce LiOH solution, for subsequent conversion by evaporative crystallisation to LiOH·H 2 O crystals as the end-product. Nafion® 117 cation-selective membranes were used in all experiments. The small electrolytic test cell achieved an average LiOH production rate of 7.5 g/h with 83 % coulombic efficiency and specific electrical consumption of 6.5 kWh/kg LiOH. In the large electrolytic test cell, a higher average LiOH production rate of 11.2 g/h was attained but at lower coulombic efficiency (62 %) and greater specific electrical consumption (8.8 kWh/kg LiOH). In a longer period ED process, there was a further decrease in coulombic efficiency and an increase in the specific electrical consumption. Also, the cation-selective membranes were found susceptible to the deportment of cation and anion impurities (i.e . , Na + , K + , and Cl - ), which impacted the LiOH·H 2 O product purity. Higher purity LiOH·H 2 O was obtained from the LiOH liquor produced in the ED testwork by subjecting the liquor to partial evaporation under a nitrogen gas blanket. Further optimisation of the process parameters is expected to enhance the yield and purity of the LiOH·H 2 O product and reduce operating costs.