Recovery of Lithium Using a novel amide-neutral phosphorus-based extraction system with response surface methodology optimization

Tributyl phosphate (TBP) is a popular neutral organophosphorus extractant, but its high concentration may result in severe corrosion of equipment. In this study, lithium was extracted using a novel system comprising N, N-(2-ethylhexyl)-3-oxobutanamide/TBP/sulfonated kerosene/FeCl3. A series of saturated magnesium chloride (MgCl2) solutions mixed with different lithium chloride monohydrate concentrations were used for single-factor experiments to extract lithium. A saturated MgCl2 solution with 2.22 g.L-1 Li+ characteristically exhibited a high Mg to Li ratio and used for orthogonal tests. The volume ratio of the organic to aqueous phases, molar ratio of Fe to Li, and volume concentration of TBP were investigated and systematically optimized through response surface methodology. A total of 94.55% lithium were extracted under the following optimized condition: an organic/aqueous ratio of 2.60, [ Fe]/[ Li] of 1.38, and TBP vol. % of 31.37%. The results showed the system enhanced the lithium extraction efficiency and also significantly decreased the TBP concentration.