Selective extraction and separation of nickel from cobalt, manganese and lithium in pre-treated leach liquors of ternary cathode material of spent lithium-ion batteries using synergism caused by Versatic 10 acid and LIX 84-I

• Extraction curves of Ni(II) were shifted to left by increasing Versatic 10 acid.
• Curves for Co(II) and Mn(II) were shifted to right by increasing Versatic 10 acid.
• At pH 5, the largest synergistic enhancement coefficient of Ni(II) (R = 16.49) was observed.
• Selective extraction of Ni(II) is feasible with 3 stage extraction by McCabe–Thiele diagram.
• LIX 84-I acts as the extractant and Versatic 10 acid plays the role of the synergist.

The extraction of nickel from a leach liquor containing cobalt, manganese and lithium of Li-ion batteries cathode material using a mixture of Versatic 10 acid and LIX84-I was investigated. The leach liquor of LiB cathode material obtained with H2SO4/H2O2 as the lixiviant was purified by precipitating the leached aluminum, iron and copper as hydroxides by adjusting the pH to ~ 5. To extract nickel, the effect of Versatic 10 acid concentration was the experimental variable in the mixture of extractants. The pH-isotherms revealed the synergistic effect on nickel caused by the increasing concentration of Versatic 10 acid which decreased the pH50 for nickel extraction and pH 5 was chosen as the most suitable pH for solvent extraction. A loading isotherm at pH 5 was constructed by changing the O/A ratio. The McCabe Thiele diagram predicted the possibility of using three stages to extract over 98% nickel, which was confirmed experimentally. The stripping test was carried out from loaded organic of Versatic 10 acid alone, LIX 84-I alone and the combination of Versatic 10 acid and LIX 84-I. Slow stripping of nickel from LIX 84-I indicated that LIX 84-I and Versatic 10 acid acted as the extractant and synergist, respectively.

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