Investigation on Addition of Neodymium Magnets in Hydrometallurgical Citric Acid Leaching of Rare Metals from Spent Lithium-ion Cells

The development of lithium-ion batteries has brought a revolution in electric devices. However, a growing number of electronics and electric cars pose a severe waste management challenge due to primitive lithium-ion battery recycling methods. For this reason, strong organic acid hydrometallurgical leaching received considerable attention due to its biodegradability and zero production of toxic byproducts. Citric acid, although an excellent choice from a sustainability standpoint, has not been thoroughly investigated as a leaching reagent due to its low leaching efficiency of 80%; whereas, stronger and more expensive methane sulfonic acid was able to achieve a leaching efficiency of 99.5%. However, in this study, the use of different configurations of N52 neodymium magnets in citric acid leaching was studied to examine its effect on the leaching of lithium and cobalt from LiCoO ₂ lithium-ion batteries. It was proven that the addition of 25 N52 neodymium magnets in citric acid leaching was able to increase the leaching efficiency of cobalt by approximately 15%. With the addition of N52 neodymium magnets, citric acid leaching efficiency of cobalt was able to achieve 95%, close to that of methane sulfonic acid, making citric acid a competitive candidate for a leaching reagent. Considering the price discrepancy of 4200% between citric acid and methane sulfonic acid and as citric acid can also be easily obtained from fruit waste, citric acid leaching using N52 neodymium magnets can make the battery recycling process cheaper, eco-friendlier, and more sustainable.