Direct extraction of lithium from a salt-lake brine of low-chloride and high‑calcium using a TBP-FeCl3 solvent extraction system and stripping with HCl

Abstract

The increasing adoption of lithium-ion batteries in new energy sectors has substantially increased lithium consumption. Chilean salt lakes consist of high concentrations of Li⁺, (1.14 g/L) and Ca²⁺ (>10 g/L) and low concentration of Cl⁻ (<200 g/L). The TBP-FeCl₃ system can efficiently extract lithium from high Mg brine, but the system has not yet been studied in low chloride and high calcium brine. In this paper, the effect of different extraction, scrubbing, and stripping conditions on the lithium extraction percentage from this type of brine was investigated using a TBP-FeCl₃ system. The results indicated that 100 % TBP mixed with brine containing 15–20 g/L Fe³⁺ and 0.05 mol/L HCl at O/A = 1:1, extracted 52.9 % of Li⁺ and produced an organic phase of 0.72 g/L Li⁺, accompanied by Ca²⁺ and Na⁺ concentrations of 2.82 g/L and 2.47 g/L, respectively. The extraction percentage of Li⁺ reached 74.2 % after a four-stage extraction process. The loaded organic phase was scrubbed with 4 mol/L LiCl solution at O/A = 1:1, and the scrubbing percentage of the impurity ions was >90 %. The scrubbed organic phase was stripped by simulated counter-current stripping by 2.5 mol/L HCl at O/A = 15:1 for ten stages, and the recovery of Li⁺ was 80.3 %. The stripping solution had a Li⁺ concentration of 25.3 g/L and an impurity ion concentration of <1 g/L and the loss of Fe³⁺ was <100 mg/L. The TBP-FeCl₃ extraction system offers the efficient and direct extraction of lithium from Chilean brine and provides technical support for the clean mining of lithium resources in South American salt lakes.