Sustainable Mining and Metallurgy

A novel process for the recovery of nickel, cobalt, manganese and lithium from spent lithium battery cathode materials was proposed. Nickel, cobalt, manganese and lithium metals in cathode materials were recovered by two-step carbothermal reduction-hydrometallurgical leaching process, and the recovery mechanism and process of valuable metals in cathode materials were studied. The results show that lithium metal is preferentially extracted by two carbothermal reduction processes. Under the optimum conditions of calcination temperature 650℃, carbon content 8%, water immersion time 2h, pyrolysis temperature 95℃ and pyrolysis time 4h, the lithium recovery rate can reach 88.7%, and the purity of lithium carbonate is 98.84%. The valuable metals of nickel, cobalt and manganese were recovered by hydrometallurgical leaching process. The valuable metals of nickel, cobalt and manganese were recovered by wet leaching process. The optimum experimental conditions of high acid leaching process were as follows: the amount of hydrogen peroxide was 1.2 times of the theoretical amount, the leaching temperature was 60℃, the leaching time was 2h, and the pH value of the solution was 1.5. The optimum experimental conditions for the iron and aluminum removal process are temperature 90℃, reaction time 2h, and solution pH value 3.5. Under the optimum conditions, the yields of nickel, cobalt and manganese were 99.4%, 99.5% and 98.9%, respectively.