Leaching of Valuable Metals from Roasted Residue of Spent Lithium-ion Batteries with Ammonium Sulfate

Spent lithium-ion batteries(LIBs) blended with ammonium sulfate were roasted at elevated temperature.The effects of pH value of sulfuric acid leaching solution,roasting temperature and amount of ammonium sulfate on leaching rates of metal elements were investigated.Roasted residue was also leached with a mixed solution containing ammonia and ammonium sulfate.The results showed that all of lithium could be leached out.Due to the metallic copper in the roasting residue,the leaching rate of copper only reached 92.86% in sulfuric acid solution,but could be up to 97.60% in ammoniacal solution.Under the experimental conditions,the leaching rate was lower than 68% for cobalt because of undissolved Co3O4 in the roasted residue.The leaching rate of total cobalt was more than 99% when high concentration sulfuric acid with volume ratio of sulfuric acid to water at 1:2 was employed to treat the above leached residue.