Experimental Study On Recovery Of Cobalt From Waste Lithium Cobaltate Battery By Citric Acid Leaching-electrochemical Deposition Method

Due to the rapid upgrading of electronic products and the increase in the demand for lithium ion batteries,the scale of waste lithium ion batteries continues to expand..The clean and efficient resource treatment of waste lithium-ion batteries can not only avoid environmental pollution,but also relieve the pressure of China's lack of Co resources,which is conducive to sustainable development.Therefore,this paper adopts the combined method of citric acid leaching-electrochemical deposition to recover Co from waste lithium cobalt acid battery.The paper studies the effect of citric acid reduction acid leaching system on the direct separation of positive electrode leaching and the law and influencing factors of Co recovery from citric acid leaching solution by electrochemical deposition.The main research results are as follows:(1)Citric acid reduction acid leaching system can effectively leach and separate the positive electrode,without the need for pretreatment(such as NMP solvent dissolution or high temperature pyrolysis)process,aluminum foil,conductive agent,binder and other residues in the leach residue.Through the single factor experiment,the best conditions for the positive leaching separation for cut size 1 cm x 1 cm,1.25 mol/L,citric acid concentration hydrogen peroxide dosage 15 vol.%,liquid-solid ratio of 8.5:1,the reaction temperature70?,the reaction time of 70 min,the conditions,the leaching rate of Co is 94.46%,the leaching rate of Li was 93.28%,the leaching rate of Al is 8.1%,the mass concentration on subsequent electrochemical deposition of Co in the recovered leaching liquid impact is low.The optimal conditions for recovery of Co from citric acid leaching solution by electrochemical deposition are as follows:the concentration of Na₂SO₄ is 180g/L,the temperature of electrolyte is 65?,the pH value of electrolyte is 4,the current size is 2.5A,the concentration of Na₂S₂O₃ is 30g/L,and the electrolytic time is 10 h.Under these conditions,the recovery of Co is 91.54%and the current efficiency is 49.97%.The purity of cathode cobalt obtained under the optimum conditions was 99.76%,and the content of other impurity metal elements Al,Ni and Mn were 0.056%,0.018%and 0.0007%,respectively.The results show that the electrochemical deposition method can effectively recover Co from the citric acid leaching solution,and can reduce the cost of the next refining process.In addition,in the electrolytic process,the electrolyte pH is basically stable,without adding additional buffer.