Recovery of valuable metals from cathode material from spent lithium-ion batteries

Thermodynamic analysis shows that reducing agent coke can reduce Co₃O₄, CoO and NiO to Co and Ni at 1300–1500 °C. MnO₂ is gradually carbothermal reduced to Mn₂O₃, Mn₃O₄ and MnO, while MnO is reduced to metallic Mn when the temperature is higher than 1402 °C. The effects of smelting temperature, Na₂CO₃ addition and smelting time on the retention rate of Li in slag have been studied. Using 10–20 % Na₂CO₃ as an additive can inhibit the volatilization loss of Li during the smelting of ternary cathode materials of lithium-ion batteries, and realize the enrichment of Li in slag. When the smelting temperature is 1300 °C, Na₂CO₃ addition is 20 %, and the smelting time is 60 min, the retention rate of Li in slag is as high as 96.37 %. FAAS, XRD and SEM-EDS analysis of products obtained by smelting at 1300 °C for 120 min show that the main phases of metal product were Co and Ni, among which the mass fractions of Ni, Co, Mn, and Fe are 52.9 %, 19.4 %, 8.3 % and 3.1 %, respectively. The residue after smelting at 1300 °C for 60 min is leached by sulfuric acid with the liquid-solid ratio of 2:1 at 90 °C for 60 min, and the leaching rate of Li is 82.11 %.