三室膜电解法由硫酸锂制备氢氧化锂的实验研究

Preparation of lithium hydroxide from lithium sulphate in a three-compartments membrane electrolysis system

设计了三室膜电解槽并建立了实验流程，进行了不同电流密度下的初步可行性摸索实验，并选择适宜的电流密度条件，进行了酸室、盐室、碱室初始浓度及循环流速等4个影响因素的条件优化实验．实验结果表明，电流密度在500～1800A／m^2的范围内，三室膜电解法由硫酸锂制备氢氧化锂的过程在技术上是完全可行的；电流密度在500A／m^2时，电流效率达到最高值而能耗也达到最低值．通过正交实验判断4个条件参数对电流效率和能耗的影响，得到了最优的实验条件组合；进一步的实验验证表明，在酸室、盐室及碱室的初始浓度分别为2．7、1．0及1．0mol／L，循环流量为30L／h条件下，电流效率达到66．74％，能耗达到6．37（kW·h）／kg LiOH，优于正交实验中所有结果．

A three- compartment electrolysis reactor involving CEM （cation exchange membranes） and AEM （anion exchange membranes） was designed to carry out the production of lithium hydroxide from lithium sulphate. The electrolysis process was carried out under different current densities. In the range of current density of 500-- 1 800 A/m^2, the results show that the process was feasible. In the relative low current density, the experiment under 500 A/m^2 got the highest current efficiency and lowest energy consumption. The orthogonal experiments had been schemed to determine the influence of circulation flow rate, the initial concentrations of acid stream, base stream and salt stream on the process. The optimal reaction condition was determined and verified by experiments. Under the initial concentration： 2.7 mol/L of sulfuric acid, 1.0 mol/L of lithium sulphate, 1. 0 mol/L of lithium hydroxide, 30 L/h of the circulation flow, the current efficiency of 66.74 %, energy consumption of 6.37 kW·h/kg LiOH was got, better than any group of the orthogonal experiments.