Abstract In this work, a solvent extraction process for Ca2+ and Mg2+ removal from Li+ concentrated solution consisted of 30 g/L Li+, 1.5 g/L Ca2+ and 1.5 g/L Mg2+ was proposed, using di-(2-ethylhexyl) phosphoric acid (D2EHPA) as extractant. The extraction process was a cation exchange mechanism, and the extraction sequence was Ca2+ > Mg2+ > Li+ > Na+. Under the optimum condition of 66% saponification degree, 3/2 phase ratio and three-stage extraction, the extraction efficiency of Ca2+, Mg2+ and Li+ reached 99.00%, 98.57% and 15.28%, respectively. The extracted cations could be completely stripped by HCl solution, and the co-extracted Li+ could be selectively stripped and separated from Ca2+ and Mg2+ using higher concentration HCl solution at higher phase ratio. A whole removal process for Ca2+ and Mg2+ involving extraction, scrubbing, stripping and saponification sections was put forward, and the process stability was continuously tested on centrifugal extractors. Removal efficiency of Ca2+ and Mg2+ reached 99.05% and 98.48% respectively. Meanwhile, the loss ratio of Li+ was as low as 5.22%.

中文翻译：

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D2EHPA溶剂萃取法去除浓缩锂溶液中的钙和镁

摘要 本研究提出了一种溶剂萃取工艺，采用二(2-乙基己基)磷酸从30 g/L Li+、1.5 g/L Ca2+和1.5 g/L Mg2+组成的Li+浓缩液中去除Ca2+和Mg2+。 (D2EHPA) 作为萃取剂。萃取过程为阳离子交换机制，萃取顺序为Ca2+>Mg2+>Li+>Na+。在66%皂化度、3/2相比、三级萃取的最佳条件下，Ca2+、Mg2+和Li+的萃取效率分别达到99.00%、98.57%和15.28%。提取的阳离子可以被 HCl 溶液完全汽提，而共提取的 Li+ 可以使用更高浓度的 HCl 溶液以更高的相比从 Ca2+ 和 Mg2+ 中选择性地汽提和分离。Ca2+ 和 Mg2+ 的整个去除过程包括萃取、洗涤、提出了汽提和皂化工段，并在离心萃取器上连续测试了工艺稳定性。Ca2+和Mg2+的去除效率分别达到99.05%和98.48%。同时，Li+的损失率低至5.22%。