Mechanism and process for the extraction of lithium from the high magnesium brine with N,N-bis(2-ethylhexyl)-2-methoxyacetamide in kerosene and FeCl3

The degradation of TBP has become a stumbling block to the industrial continuous production of lithium chloride extraction from brines with high Mg/Li ratio by solvent extraction. To develop a more stable and more efficient extraction system, a novel amide system, containing newly synthesized extractant N,N-bis (2-ethylhexyl)-2-methoxyacetamide (NBEHMOA), FeCl3 6H(2)O and sulfonated kerosene, was proposed in this work. Compared with TBP and N523, NBEHMOA extracted Li+ and H+ in the sequence of TBP. NBEHMOA. N523 and N523. TBP. NBEHMOA respectively. The solution containing 5.5 mol/L LiCl and 0.5 mol/L HCl was used as the eluent in the scrubbing process. A Li+ extraction efficiency of 96.7% and 22.31 g/L Li+ in the stripping solution were achieved by the whole process with counter-current twelve stages. The extraction mechanism investigated via FT-IR spectroscopy illustrated that the metal ions Fe3+ and Li+ were mainly coordinated by the carbonyl C = O in NBEHMOA. This novel amide system can successfully achieve the cascade extraction effect for lithium, Li/Mg separation and avoid the generation of phase interface objects through counter-current extraction of lithium from brine at a lower acidity. This work provided a novel extraction system to recover lithium from the higher magnesium/lithium ratio brines. (c) 2022 Published by Elsevier B.V. on behalf of The Korean Society of Industrial and Engineering Chemistry.

Automated summary

A novel amide system containing N,N-bis (2-ethylhexyl)-2-methoxyacetamide (NBEHMOA), FeCl3 6H(2)O, and sulfonated kerosene was proposed for continuous extraction of lithium chloride from brines with high Mg/Li ratio. NBEHMOA showed higher and more stable Li+ and H+ extraction efficiency compared to conventional TBP and N523. The counter-current extraction process achieved high Li+ extraction efficiency and Li+ concentration in the stripping solution. FT-IR spectroscopy revealed the coordination mechanism between NBEHMOA and metal ions.