Recovery of lithium from leach solutions of battery waste using direct solvent extraction with TBP and FeCl3

Although societal interest in lithium has grown due to its increased demand for manufacturing of lithium ion batteries (LIBs), recent research studies about LIB recycling with solvent extraction did not focus on Li recovery and Li remained in the raffinate contaminated with impurities. In this research presented direct Li recovery from LIB waste leachate prior to Ni and Co is a novel and promising approach. The applied SX system (tributyl phosphate (TBP) as extractant and iron(III) chloride (FeCl3) as co-extractant in kerosene) is known from Li separation from natural brines. Batch equilibrium experiments at room temperature were conducted with preloaded organic phase (NaCl and FeCl3, TBP (80% (v/v)) and kerosene (20% (v/v)) and synthetic aqueous LIB waste leachate solution (1.3-1.5 g L-1 Al, 14.2-17.8 g L-1 Co, 1.9-2.2 g L-1 Cu, 0.7-0.8 g L-1 Fe, 2.4-2.7 g L-1 Li, 1.9-2.1 g L-1 Mn, 1.8-2.0 g L-1 Ni, E = 603 mV Ag/AgCl). Loading with emphasis on the competitive extraction between Li and H+, substitution of MgCl2 as chloride source and variation of the phase ratios as well as scrubbing and stripping are investigated in this research. Lithium was selectively separated over divalent LIB metals (Mn, Cu, Co, Ni) and Al(III) from a multicomponent mixture, and the extraction ability of the system is H+ > Li+ > > LIB metals. Aiming for maximum Li extraction initial concentration of H+ was chosen to be 0.1 M. Substitution of MgCl2, used in the brine systems, by AlCl3 as chloride source promoted Li extraction (E(Li) = 87.7% for R(O/A) = 1) due to its strong salting out effect. This resulted in enhanced separation factors (beta(Ni) = 2825 and beta(Co) = 854 for R(O/A) = 1). Loaded organic phase was purified using 1 M LiCl +2 M AlCl3 scrubbing solution prior stripping. Stripping with 6 M HCl in single-stage at R(O/A) = 5 resulted in stripping liquor containing 12.26 g L-1, 0.02 g L-1, 0.04 g L-1, and 0.04 g L-1 of Li, Mn, Co and Cu, respectively.

Automated summary

This research successfully demonstrated a novel approach to directly recover lithium from LIB waste leachate with effective separation and purification. Through experimental validation, the method showed high selectivity and separation efficiency when dealing with multicomponent metal leachates simultaneously.