Journal of Chemical Engineering of Japan, Vol.52, No.6, 508-513, 2019
Solvent Extraction Process and Extraction Mechanism for Lithium Recovery from High Mg/Li-Ratio Brine
A co-extraction system of tributyl phosphate (TBP) and KPF6 was used for lithium ion extraction from brine containing a high ratio of magnesium and lithium. The effects of the phase ratio R(organic/aqueous), aqueous phase pH, and PF6-/Li+ molar ratio on the extraction of lithium were studied. The single-stage extraction efficiency of lithium was 82.29% under optimal conditions, and the back-extraction efficiency was 93.99% when using 1 mol/L HCl + 3 mol/L NaCl as the stripping agents at R(O/A) = 1. The stoichiometry of the extraction complex was investigated by nuclear magnetic resonance spectroscopy and slope analysis.