Dry Grinding - Carbonated Ultrasound-Assisted Water Leaching of Carbothermally Reduced Lithium-Ion Battery Black Mass Towards Enhanced Selective Extraction of Lithium and Recovery of High-Value Metals

This paper presents a dry grinding and carbonated ultrasound-assisted water leaching (CUAWL) process for recycling the black mass of spent lithium-ion batteries constituting anode material (graphite) and different cathode material combinations (LiCoO2, LiMn2O4, and LiNiO2). The inspiration of the method is to enhance selective Li2CO3 recovery and reduce energy requirements for evaporative crystallization while achieving maximum recovery of all the high-value metals. The influence of several factors, including roasting temperature, roasting time, grinding time, water leaching time, water leaching temperature, sonication, and CO2 flow rate, on the leaching efficiency of metals are investigated. The SEM-EDS and XRD results depict that the mixture of anode and cathode material after reduction roasting under optimum conditions of 600 °C for 30 min was primarily transformed into Li2CO3, Ni, CoO, Co, and MnO. However, the selective recovery of Li with water leaching was low, and dry grinding followed by CUAWL was adopted to enhance the recovery rate. The optimized experimental results achieved improved results for selective recovery of Li of up to 92.25% for the mixture of multiple cathode materials (LiCoO2, LiMn2O4, and LiNiO2). The recovered leach solution (LiHCO3) is subjected to evaporative crystallization to attain high-purity Li2CO3 (≥99.2%). Subsequently, over 99% of the high-value metals Ni, Mn, and Co could be leached out using 4 M H2SO4 without the addition of a reductant.