Extraction of Lithium From Salt Lake Brine with High Mg/Li Mass Ratio by N523-DIBK Extraction System

To develop a more stable and more efficient extraction system, a novel amide extraction system, containing extractant N , N -bis(2-ethylhexyl) acetamide (N523) and diluent diisobutyl ketone (DIBK), was proposed in this work. A series of operation conditions, such as the concentration of initial lithium in aqueous phase, the volume ratio of N523 and DIBK, phase ratio of O / A , the molar ratio of Fe/Li, were carried out. The lithium extraction rate reached up to 92% under the optimal extraction conditions. Considering the mass transfer of two phases and consumption of extractant, the three-stage counter-current extraction experiment was conducted. After 6 cycles experiment of the three stage counter-current extraction, the lithium extraction rate reached 99.89% and the separation factor of Li/Mg, Li/Na, Li/K, and Li/Ca were 103,300, 5288, 5233, and 760.4, respectively. The stoichiometry of the complex was LiFeCl 4 ·N523 by the slope method. The results indicated that N523-DIBK extraction system was effective to recovery of lithium from salt lake brine with high mass ratio of Mg/Li. Furthermore, the extraction thermodynamics study revealed lithium extraction was an exothermic process, which meant lower temperature promoted lithium extraction. Graphical Abstract