混盐型高锂卤水萃取分离锂

以阿根廷某高锂混盐型盐湖卤水萃硼后得到的萃余液为研究对象,采用磷酸三丁酯(TBP)- FeCl3体系萃取分离锂,考察了铁锂比、TBP浓度、稀释剂种类、萃取相比O/A、有机添加剂种类及浓度等因素的影响,优化了萃取工艺参数,分析了锂在萃取两相体系中的分配行为以及锂与镁、钠和钾的分离情况。在有机相组成为65% TBP - 5%MIBK - 30% 260#溶剂油、铁锂比1.5:1、相比O/A=2:1、萃取混合时间5 min、室温的条件下,锂的单级萃取率大于79%,镁、钠、钾的萃取率分别仅有5.24%、8.57%和0.88%,Li与Mg、Na、K的分离系数分别达到62、37和388,TBP显示出对锂的良好选择性,且MIBK的加入改善了分相和锂萃取性能。夹带与共萃进入有机相中的镁、钠和钾可用氯化锂的稀盐酸溶液洗涤去除。负载锂的有机相可用7 mol/L盐酸进行反萃,得到富锂溶液。

Extraction and Separation of Lithium from A Salt Lake Brine with High Lithium Content

Tributyl phosphate (TBP) - FeCl3 system was used as extractant for extraction and separation of lithium from an Argentine salt lake brine of high lithium content and mixed chloride and sulfate salts after boron extraction. The effects of Fe/Li molar ratio, TBP concentration, diluent type, phase ratio O/A, organic additive type and concentration were investigated, the process parameters were optimized, and the distribution behaviors of lithium in the extraction two-phase system and the separation of lithium from magnesium, sodium and potassium were analyzed. When the organic phase formation is 65% TBP - 5% methyl-isobutyl ketone (MIBK) - 30% 260# solvent oil, the molar ratio of Fe/Li is 1.5:1, the phase ratio O/A is 2:1 and the mixing time is 5 min, the single-stage extraction yield of lithium is more than 79% at room temperature whereas the extraction yields of magnesium, sodium and potassium are only 5.24%, 8.57% and 0.88%, respectively. The separation coefficients of lithium and magnesium, sodium and potassium reach 62, 37 and 388 respectively. TBP shows good selectivity for lithium and the addition of MIBK can improve the phase separation and lithium extraction performance. Magnesium, sodium and potassium entrained and coextracted into the organic phase can be removed by washing with dilute hydrochloric acid solution of lithium chloride. The organic phase loaded with lithium can be stripped with 7 mol/L HCl solution to obtain lithium-rich solution.