盐湖卤水镁锂沉淀分离工艺研究

Study on precipitation separating technique for magnesium and lithium from salt lake brine

采用氨水和氢氧化钠作为沉淀剂,对高镁锂比卤水进行镁的二次沉淀分离以及母液蒸发浓缩提锂工艺进行研究。实验结果表明:常温下,采用质量分数为10%的氨水作为沉淀剂,可使卤水除镁率达到88.6%,实现卤水中镁锂的初步分离;在此基础上,采用氢氧化钠溶液作为沉淀剂,控制浓度为8 mol/L的氢氧化钠溶液的滴加速度为3 mL/min、反应时间为20 min、溶液终点pH=12.5、搅拌转速为120 r/min,采用漏斗过滤氢氧化镁沉淀,卤水的除镁率可达到99.8%。母液经蒸发浓缩析出氯化铵和氯化钠晶体,使锂得到富集。

With ammonia and sodium hydroxide as precipitators,the secondary magnesium precipitation separation from high-Mg-Li-content salt lake brine and the extraction of lithium by the concentration of mother solution were studied.Results showed that the magnesium removal rate could reach 88.6% with 10% （mass fraction） ammonia as the first precipitator at room temperature.Based on the preliminary separation of Mg-Li,magnesium ions remained in the solution was further removed thoroughly with sodium hydroxide as the second precipitator and the magnesium removal rate reached 99.8%, under the conditions of 8 mol/L NaOH,dropping speed 3 mL/min,reactive time 20 min,pH=12.5 at solution final point,mixing speed 120 r/min, and funnel filter mode.NHnC1 and NaC1 crystals were obtained while the solution was concentrated, so that lithium was enriched.