| Title |
Citric Acid-based Selective Leaching for Purification of Pyrometallurgically Recycled NCM |
| Authors |
한도현(Dohyeon Han) ; 이주헌(Juheon Lee) ; 한수철(Sucheol Han) ; 이헌묵(Hunmook Yi) |
| DOI |
https://doi.org/10.3365/KJMM.2026.64.8.734 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
Carbothermic reduction; LIB recycling; NCM; Organic acid leaching; Pyrometallurgy |
| Abstract |
Pyrometallurgical recycling of spent LiNixCoyMn1-x-yO2 (NCM) lithium-ion batteries (LIBs) has attracted considerable attention owing to its high feedstock flexibility and suitability for large-scale processing. Recent studies have reported that carbothermic reduction-based pyrometallurgical processes can induce chemical phase separation through the control of oxygen partial pressure, thereby enabling the selective separation and recovery of valuable components based on differences in their physicochemical properties. However, previous studies have mainly focused on Li recovery, whereas the purification of a Ni-Co from pyrometallurgically recycled NCM, which primarily consists of a Ni-Co alloy, MnO, and LiAlO2, remains insufficiently investigated. In this study, a citric acid-based selective leaching process was proposed for the selective removal of MnO and LiAlO2 to recover high-purity Ni-Co from pyrometallurgically recycled NCM. Citric acid concentration (5, 10, and 20 wt%), leaching time (0.5, 1, and 2 h), and reaction temperature (20-80 °C) were selected as the major process variables. Thermodynamic calculations indicated that MnO and LiAlO2 exhibited a higher driving force for dissolution than Ni, Co, confirming the thermodynamic feasibility of selective leaching. Experimental results showed that MnO achieved a leaching efficiency higher than 95%, while LiAlO2 reached a maximum leaching efficiency of 89.5%. In contrast, the leaching efficiency of the Ni-Co remained below 5% under all experimental conditions. These results indicate that the selective leaching of MnO and LiAlO2 was successfully achieved, leading to the purification of the Ni-Co phase. Under the optimal conditions, a Ni-Co purity of 90.14% and a recovery ratio of 96.75% were achieved. The proposed process demonstrates an environmentally friendly purification route for improving the efficiency and economic viability of spent battery recycling. |