二(2-乙基己基)磷酸(D2EHPA)萃取分离镁和锂

Separation of magnesium and lithium by solvent extraction using di-(2-ethylhexyl) phosphoric acid(D2EHPA)

为获得从高镁锂离子浓度比卤水中分离锂的方法,提出了利用溶剂萃取法从卤水中提取镁以降低镁锂离子浓度比的研究思路。以二(2-乙基己基)磷酸(D2EHPA)为萃取剂,煤油为稀释剂,对模拟盐湖卤水进行萃取实验研究。结果表明,皂化后D2EHPA对Mg2+具有较好的选择分离性能;在相比和皂化率相同的条件下,D2EHPA的浓度越大越有利于Mg2+的萃取;为防止有机相粘度过大,皂化率不宜高于80%,D2EHPA的浓度不宜高于50%;采用MgCl2溶液对负载溶剂进行洗涤可除去其中Li+和K+,从而获得高纯度的MgCl2。

Lithium is difficult to directly separate from brine from the salt lake because of the high concentration ratio of Mg^2＋/Li^＋. Solvent extraction was used to extract magnesium from the brine to solve this problem using di-（2-ethylhexyl） phosphoric acid （D2EHPA） as the extractant and kerosene as the diluent. The saponificated D2EHPA has good Mg^2＋ extraction performance. For the same phase ratio and saponification ratio, the Mg^2＋ extration efficiency increases with the D2EHPA concentration. The saponification ratio should not be higher than 80% and the D2EHPA concentration should not be higher than 50% to avoid an excessive viscous extractant. To obtain a high purity of Mg compound, MgCl2 was used to strip the Li^＋ and K^＋ in the loaded extractant. Higher MgCl2 concentrations and phase ratios improve the stripping.