| Summary: | 碩士 === 國立中山大學 === 環境工程研究所 === 106 === A lab-scale study was conducted for evaluating the recovery of cobalt and manganese from mixed (prismatic-type and cylindrical 18650-type) spent lithium-ion batteries using hydrometallurgical processes including acid leaching, chemical precipitation, and electrowinning. In this study samples of mixed-type spent lithium-ion batteries (LIBs) collected from a local spent batteries recycling plant were subjected to various pre-treatments including crushing, sieving, and roasting. The powdered substance thus obtained was then subjected to acid digestion using a Taiwan EPA standard method. The major elemental compositions were found to be Co, Mn, Cu, and Zn. Results of the acid leaching tests showed that the optimal leaching conditions were 80˚C, 60 min, 4 M H2SO4 and 0.06 M C6H12O6 for the mixed-type spent LIBs. Then various separation methods were used for the separation of metallic ions in the leached solution. The relevant test results for the mixed-type spent LIBs are given as follows: (1) Under the condition of pH 6, 100% of Al, 100% of Fe, 95% of Cu and 88% of Zn were removed by chemical precipitation; (2) As for the liquid phase from solid-liquid separation of procedure (1), the co-precipitation efficiency of Co and Mn were 100% when pH was adjusted to 11.5, but such precipitates were re-dissolved by 0.2 M H2SO4 to form the electrolyte for the subsequent electrowinning step. Test results for electrowinning of metals are given as follows: The operation of electrowinning under the current density of 250 A/m2 for 3.5 h could recover 98% of cobalt metal and 97% of manganese oxides from Co (II) and Mn (II) contained in the electrolyte. Based on the test results obtained from the aforementioned unit operations, the overall recoveries of 92% Co and 94% Mn were obtained for the mixed-type spent LIBs. It appears that the devised recycling scheme for the recovery of cobalt and manganese from mixed-type spent LIBs has a potential to be scaled up for commercial implementation.
|
|---|
