Extraction of manganese by alkyl monocarboxylic acid in a mixed extractant from a leaching solution of spent lithium-ion battery ternary cathodic material

• Antagonistic effect was proofed for Co and Mn extraction in Versatic 10 acid/D2EHPA.
• Antagonistic effect made a decrease of loading capacity for D2EHPA.
• Separation factor of Mn over Co was maximum in Versatic 10 acid/D2EHPA.
• In loaded organic, over 98% of Mn was extracted and impurities were removed by EDTA.
• Mn in loaded organic phase was stripped by 0.5 mol L−1 H2SO4.

We investigate the separation of manganese by an antagonistic effect from a leaching solution of ternary cathodic material of spent lithium-ion batteries that contain 11,400 mg L−1 Co, 11,700 mg L−1 Mn, 12,200 mg L−1 Ni, and 5300 mg L−1 Li using a mixture of alkyl monocarboxylic acid and di-(2-ethylhexyl)phosphoric acid extractants. pH isotherm, distribution coefficient, separation factor, McCabe–Thiele diagram, selective scrubbing, and countercurrent extraction tests are carried out to prove an antagonistic effect and to recover manganese using alkyl monocarboxylic in the mixed extractant. Slope analysis is used to determine the extraction mechanism between a mixture of extractants and valuable metals. An increasing concentration of alkyl monocarboxylic acid in the mixture of extractants results in a decrease in distribution coefficient of cobalt and manganese, however, the separation factor value (β(Mn/Co)) increases at pH 4.5. This is caused by slope analysis where alkyl monocarboxylic acid disrupts the extraction mechanism between di-(2-ethylhexyl)phosphoric acid and cobalt. Finally, continuous countercurrent extraction in a mini-plant test demonstrate the feasibility of manganese recovery from cobalt, nickel, and lithium.