盐湖提锂后的尾液中仍含有大量的锂，直接外排至盐田会造成锂资源的浪费，并且会对盐湖系统造成破坏，而降低提锂尾液中的镁锂比是回收提锂尾液中锂的关键。采用纳滤和反渗透组合工艺成功地回收了提锂尾液中的锂。考察了7种型号的纳滤膜对提锂尾液中镁锂分离的效果，结果表明1号纳滤膜的分离效果最好。以1号纳滤膜为纳滤元件，考察了纳滤膜在不同的过滤压力、实验温度和提锂尾液稀释倍数条件下对提锂尾液中镁锂分离的效果，得到较优操作条件：过滤压力为4 MPa、提锂尾液稀释倍数为6倍、实验温度为35 ℃。以1号纳滤膜为纳滤元件，在较优操作条件下采用二级纳滤对提锂尾液进行镁锂分离，再通过反渗透对富锂液相进行浓缩，得到镁锂质量比为13.8、锂离子质量浓度为0.39 g/L的富锂液相。富锂液相经过浓缩除杂，然后与纯碱反应，可制备电池级碳酸锂。纳滤截留的镁离子含量较高的液相则外排至尾液池，经蒸发浓缩排入盐田再回收利用。

The tail solution after lithium extraction from salt lake still contains a large amount of lithium，and directly disch arging to the salt field is not only causing waste of lithium resources，but also damaging the salt lake system. Reducing the ra tio of Mg2+ to Li+ in the tail solution is the key to recovery of lithium in the tail solution.Nanofiltration and reverse osmosis combined technonlogy is successfully used to recovery the lithium in the lithium extraced tail solution.The separation effect of 7 types nanofiltration membranes on Mg2+ and Li+ in the tail solution was investigated，the results showed that 1# nanofiltration membrane has the best separation effect.Take 1# nanofiltration membrane as the nanofiltration element，the separation effect of Mg2+ and Li+ in the tail liquor was investigated under different filtration pressure，temperature and dilution ratio of the tail solution.The optimal operating conditions were as follows：the filtration pressure was 4 MPa，the dilution ratio was 6 times and the temperature was 35 ℃.The lithium extracted tail solution was separated by twostage nanofiltration under optimal operating conditions via No.1 nanofiltration membrane，then the lithium rich liquid phase was concentrated by reverse osmosis to obtain lithium riched solution with the mass ratio of Mg2+ to Li+ was 13.8 and the mass concentration of Li+ was 0.39 g/L. Lithium riched solution can be used to produce battery grade lithium carbonate by reacting with soda after concentrated and impurity removal.The liquid phase with high Mg2+ content retained by nanofiltration was discharged to the tail solution pool，then was evaporated and concentrated，and was recoverd and reused after discharging into the salt field.