The increasing demand for critical metals and mounting pressure on the environmental impact of solid waste disposal have widely attracted the recycling of spent lithium ion batteries (LIBs). Although the hydrometallurgical recycling of LiCoO cathode materials from spent LIBs has been commonly investigated, the studies on LiNiCoMnO type cathode materials are infrequent. Hence, the present work is focused on sulfuric acid leaching of LiNiCoMnO cathode material for resource recovery of all the critical and rare metals from spent LIBs. The process parameters viz., pulp density, acid concentration, the dosage of reducing agent (i.e., HO), time, and temperature have been optimized for leaching of cathode powder (of weight composition: 7.6% lithium, 20.48% cobalt, 19.47% manganese, and 19.35% nickel). The maximum 92% lithium and nickel, 68% cobalt, and 34.8% manganese could be leached while leaching a 5% pulp density in 3.0 M HSO without HO at 90 °C. Leaching efficiencies of metals were found to be increased within 30 min and reaching to >98% by adding 4 vol% HO even at a lower temperature, 50 °C. Thereafter selective precipitations of manganese and nickel were carried out from leach liquor using KMnO and CHNO as suitable precipitants, respectively. Subsequently, a 2-stage solvent extraction using 0.64 M Cyanex 272 (50% saponified) at equilibrium pH 5.0 and O:A of 1:1 was employed for recovery of a highly pure solution of CoSO. Finally, lithium could be precipitated at Li:NaCO of 1.2:1.0 and a process flow-sheet has been proposed for the recycling of spent LIBs.

中文翻译：

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废旧锂离子电池湿法冶金回收稀有金属的资源化

对关键金属的需求不断增加，以及固体废物处理对环境影响的压力越来越大，广泛吸引了废旧锂离子电池（LIB）的回收利用。尽管从废锂离子电池中湿法冶金回收LiCoO正极材料已被广泛研究，但对LiNiCoMnO型正极材料的研究却很少。因此，目前的工作重点是对 LiNiCoMnO 正极材料进行硫酸浸出，以从废锂离子电池中回收所有关键金属和稀有金属。优化了阴极粉末浸出的工艺参数，即矿浆密度、酸浓度、还原剂（即 H2O）用量、时间和温度（重量成分：7.6% 锂、20.48% 钴、19.47%）锰和 19.35% 镍）。在 90 °C、不含 H2O 的 3.0 M HSO 中浸出浓度为 5% 的矿浆时，可浸出最多 92% 的锂和镍、68% 的钴和 34.8% 的锰。研究发现，即使在较低温度（50 °C）下，添加 4 vol% H2O 后，金属的浸出效率在 30 分钟内即可提高，并达到 >98%。此后，分别使用 KMnO 和 CHNO 作为合适的沉淀剂，从浸出液中选择性沉淀锰和镍。随后，使用 0.64 M Cyanex 272（50% 皂化）在平衡 pH 5.0 和 O:A 1:1 下进行两阶段溶剂萃取，以回收高纯度的 CoSO 溶液。最后，锂可以在 1.2:1.0 的 Li:NaCO 下沉淀，并提出了回收废锂离子电池的工艺流程图。