Recovery of High-Purity Lithium Compounds from the Dust of the Smelting Reduction Process for Spent Lithium-Ion Batteries

Abstract

The recovery of valuable metals such as cobalt, nickel, and lithium from spent lithium-ion batteries (LIBs) has attracted much attention. In this study, a hydrometallurgical process for the recovery of high-purity lithium compounds like Li2CO3 and Li3PO4 from dust containing Li, Co, Ni, Cu, Fe, Mn, and Si produced during the smelting reduction of spent LIBs was investigated. The separation of Li over other metals from the dust was achieved by two methods. The first method was to leach metals from the dust with distilled water and then to precipitate the dissolved metal ions from the leaching solution at pH 10. The second one was to mix the dust with solid NaOH, following the dissolution of the mixture with distilled water. Optimum conditions for the second method were a 1:0.17 weight ratio of dust to NaOH, 50 g/L pulp density for 120 min at 22oC. These two methods resulted in a solution containing only Li(I) and Na(I). The precipitation of Li(I) to Li2CO3 from the leaching solution by Na2CO3 with the addition of acetone or ethanol was optimized a 1:0.5 molar ratio of Li(I) to Na2CO3, 6:5 volume ratio of solvent to Li(I) solution for 30 min at 22oC. Under the optimum conditions, the precipitation percentage of Li(I) was higher than 92.0% with above 99.0% purity. Additionally, using Na3PO4, 97.1 % Li(I) was precipitated from the leaching solution to Li3PO4 with 93.1% purity. An optimized process for the recovery of lithium compounds from the dust is proposed.