Sustainable Mining and Metallurgy

Aiming at the problems of long process, high acid consumption and low recovery rate of lithium in the conventional recycling process of spent ternary lithium battery black powder, combined with the actual production situation, a series process of reduction roasting-two-stage acid leaching for lithium extraction was studied. The structural transformation of lithium ions in the cathode black powder was realized by carbothermal reduction roasting pretreatment, and then the pH condition of the solution was controlled by stages for two-stage dilute acid leaching. In this process, there is no need to add additional impurity removal agent, which realizes the efficient separation of lithium and cobalt, nickel and manganese impurity elements. The effects of different roasting temperature, roasting time, dosage of carbonaceous reductant, liquid-solid ratio, leaching time, leaching temperature and sulfuric acid concentration during acid leaching on lithium extraction were investigated by single factor method. The results show that the leaching rate of lithium is 97.23% and the leaching rate of cobalt, nickel and manganese is less than 0.6% under the conditions of reducing agent ratio of 15%, sintering temperature of 600℃, roasting time of 100min, leaching liquid-solid ratio of 6mL/g, leaching time of 120min, leaching temperature of 70℃, and sulfuric acid concentration of 1mol/L. The lithium precipitation precursor prepared by this process was further precipitated with sodium carbonate, resulting in a direct lithium yield of 88.61%.