Hydrometallurgical process for recovery of cobalt from waste cathodic active material generated during manufacturing of lithium ion batteries

What is it about?

The paper embodies a new leaching-solvent extraction hydrometallurgical process for the recovery of pure and marketable form of cobalt sulfate solution from waste cathodic active material generated during manufacturing of lithium ion battery. Leaching of the waste was investigated as function of leachant H2SO4 concentration, leaching time, temperature, pulp density and reductant H2O2 concentration. The 93% of cobalt and 94% of lithium were leached at suitable optimum condition of pulp density 100 g/L, 2 M H2SO4, 5 volume % of H2O2, leaching time 30 minutes and temperature 75 oC. In subsequent solvent extraction studies with leach liquor of pH 5, 85.42% of cobalt was recovered using 1.5 M Cyanex 272 as an extractant at O/A ratio of 1.6. The rest of the cobalt was totally recovered from the raffinate using 0.5 M of Cyanex 272 at O/A ratio 1, feed pH of 5.35. Then co-extracted lithium was scrubbed from the cobalt loaded organic using 0.1 M Na2CO3. Finally, the cobalt sulfate solution with purity 99.99% was obtained from cobalt loaded organic by stripping with H2SO4.

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Why is it important?

The paper embodies a new leaching-solvent extraction hydrometallurgical process for the recovery of pure and marketable form of cobalt sulfate solution from waste cathodic active material generated during manufacturing of lithium ion battery. Leaching of the waste was investigated as function of leachant H2SO4 concentration, leaching time, temperature, pulp density and reductant H2O2 concentration. The 93% of cobalt and 94% of lithium were leached at suitable optimum condition of pulp density 100 g/L, 2 M H2SO4, 5 volume % of H2O2, leaching time 30 minutes and temperature 75 oC. In subsequent solvent extraction studies with leach liquor of pH 5, 85.42% of cobalt was recovered using 1.5 M Cyanex 272 as an extractant at O/A ratio of 1.6. The rest of the cobalt was totally recovered from the raffinate using 0.5 M of Cyanex 272 at O/A ratio 1, feed pH of 5.35. Then co-extracted lithium was scrubbed from the cobalt loaded organic using 0.1 M Na2CO3. Finally, the cobalt sulfate solution with purity 99.99% was obtained from cobalt loaded organic by stripping with H2SO4.

Perspectives

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In this work a hydrometallurgical process for the separation and recovery of cobalt from the waste cathodic active material (LiCoO2) generated during the manufacturing of lithium ion batteries using sulphuric acid leaching followed by solvent extraction using Cyanex 272 has been developed. From the above studies following conclusions have been drawn. 1. The best condition for leaching of cobalt from the waste LiCoO2 was found to be 2 M H2SO4 at a leaching temperature of 75 oC, pulp density of 100 g/L, and H2O2 addition amount of 5 volume % for 30 minute for our system. Under these conditions, the leaching efficiencies of cobalt and lithium were 93 % and 94 %, respectively. 2. The leaching efficiency of cobalt from the waste LiCoO2 was very low without adding H2O2, but the leaching efficiency largely increased with increases in presence H2O2. This is because H2O2 reduces Co(III) to Co(II). 3. The solvent extraction using Cyanex 272 was very effective for separation of cobalt and lithium from the sulfate leach liquor of the waste cathodic active material (LiCoO2). The quantitative recovery of cobalt with minimum lithium co-extraction was achieved using Cyanex 272 concentration of 1.5 M, an initial pH of 5, and an O/A ratio of 1.6 in a single stage. Subsequently at Cyanex 272 concentration of 0.5 M, an initial pH of 5.35, and an O/A ratio of 1, cobalt from the raffinate was effectively extracted by a single stage. By this process cobalt loss and solvent investment can be minimized. 4. The solvent extraction was followed by three stage lithium scrubbing using 0.1 M Na2CO3 solution with an O/A ratio of 3.8. Then it was stripped using 0.5 M sulphuric acid. Complete extraction of cobalt with 99.99 % of purity as CoSO4 solution was obtained by managing the suitable volume and concentration of H2SO4 solution. 5. The obtained cobalt sulfate solution with high purity can be used for making salt/metal. The process is effective for recycling of waste, conservation of the natural resources and to curtail the environmental pollution.

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