(中南大学 冶金与环境学院,长沙 410083)
摘 要: 本文研究了富锂液中锂的选择性提取工艺,通过磷酸盐选择性沉淀实现了富锂液中杂质的净化和锂的高效提取。通过磷酸盐沉淀过程热力学分析,考察了富锂液磷酸盐净化除镁的效果,详细研究了富锂液初始锂浓度、反应时间、磷酸盐用量、反应温度对沉锂过程的影响。针对低温低锂浓度下沉锂效果不佳的问题,提出了反溶剂沉淀法和晶种诱导法以强化沉淀效果。结果表明:在15 ℃下,采用磷酸盐除镁,镁的去除率可达98.73%。沉锂过程中锂的沉淀率随着锂浓度、反应时间、磷酸盐用量、反应温度的增加而提升。通过磷酸锂晶种诱导法可以有效地强化低温沉锂效果,在15 ℃下,晶种用量为理论用量的1.5倍时,锂的沉淀率可达82.5%,母液残余锂浓度可降至0.35 g/L。
关键字: 锂;磷酸锂;沉淀;提取;反溶剂;晶种诱导
(School of Metallurgy and Environment, Central South University, Changsha 410083, China)
Abstract:In this paper, the selective extraction process of lithium in lithium-enriched solution was studied, and the purification of impurities in lithium-enrich solution and the efficient extraction of lithium were achieved by phosphate selective precipitation. The effect of phosphate removal of magnesium from lithium-enrich solution was investigated by thermodynamic analysis of phosphate precipitation process, and the effects of initial lithium concentration, reaction time, phosphate dosage and reaction temperature of lithium-enrich solution on lithium precipitation process were studied in detail. For the problem of poor lithium precipitation efficiency at low temperature and low lithium concentration, the anti-solvent precipitation method and seed-induced method were proposed to enhance the precipitation efficiency. The results show that the magnesium removal rate can reach 98.73% at 15 ℃ by phosphate precipitation. The precipitation rate of lithium in the lithium precipitation process is increased with the increase of lithium concentration, reaction time, phosphate dosage and reaction temperature. The low-temperature lithium precipitation efficiency can be effectively enhanced by the Li3PO4 seed induction method, and the lithium precipitation rate can reach 82.5% at 15 ℃ when the seed usage is 1.5 times of the theoretical precipitation amount, and the residual lithium concentration of the mother liquor can be reduced to 0.35 g/L.
Key words: lithium; lithium phosphate; precipitation; extraction; anti-solvent; seed-induced