Research On The Recovery Of Copper, Cobalt And Iron By Co-processing Waste Lithium Cobalt Oxide Batteries With Copper Slag Depletion Process

Approximately 80% of the world’s copper is produced by pyrometallurgical process.A large amount of copper slag produced by pyrometallurgical process is often diluted by slow cooling flotation method and pyrometallurgical reduction cleaning method.In the slow cooling flotation process,the heat of hot copper slag can not be fully utilized,and the electric furnace cleaning process consumes a large amount of carbon reducing agent.At the same time,the pyrometallurgical recovery of lithium-ion batteries needs high temperature environment and reducing agent.Therefore,this paper takes converter copper slag and waste lithium-ion battery as the research object,takes carbon/aluminum component in waste lithium-ion battery as reducing agent,and adopts electric furnace cleaning method to carry out experimental verification,so as to realize the collaborative and efficient treatment of copper slag cleaning and waste lithium-ion batteries.Firstly,the thermal decomposition characteristics of spent lithium-ion batteries were studied.The thermal decomposition process of Li Co O₂ was divided into three steps.The reaction mechanism was random nucleation and subsequent growth.The initial thermal decomposition temperature was about 738℃,which was lower than the theoretical thermal decomposition temperature（900℃）,and the total weight loss was about 9.11%,which was slightly higher than the theoretical weight loss rate（8.18%）Mass loss of electrolyte and other impurities;The high-temperature reduction ability of carbon/aluminum reducing components in spent lithium-ion batteries was experimentally verified.In nitrogen atmosphere,the carbothermal reduction of Li Co O₂ was a multi-step reaction at 20-1250℃,and the reaction mechanism was random nucleation and subsequent growth.In argon atmosphere,the aluminothermic reduction reaction takes place before the thermal decomposition reaction of Li Co O₂material,the weight loss rate is 0.74%,and the final products are Co O and Li Al O₂.After verifying the feasibility of carbothermal reduction of Li Co O₂,the effects of melting temperature,settling time and Ca O dosage on metal recovery were studied.The results show that when the ratio of copper slag to LCO batteries material is 7:1,the amount of calcium oxide is 7.5wt%,the melting temperature and holding settling time are 1475℃and 15min respectively,the copper content in slag decreases from4.49wt%to 0.37wt%;The recoveries of Cu and Co were 93.25%and 99.29%,respectively.It can be seen that the process can realize the comprehensive recovery of valuable metal resources from waste lithium-ion batteries and copper slag.Finally,the deposition law of each metal in the alloy was studied:in the Cu-Co-Fe alloy obtained by reduction smelting,the Co-Fe phase and the Cu phase constitute the basic phase of the alloy,the cobalt element distributes uniformly in the iron rich region and exists in the form of intermetallic compound,the impurity elements in the alloy are lead and zinc,and the zinc element has a high solid solubility in copper,so that the zinc element mainly distributes uniformly in the copper phase;The lead element distributes uniformly and accumulates at the junction of the two phases.The research of copper slag cleaning collaborative treatment of spent lithium-ion batteries to recover valuable metals is a new method of comprehensive utilization of resources,which integrates the clean recovery of failed lithium-ion batteries and low-carbon cleaning of copper slag.It can provide a reference for the efficient resource-based treatment of failed lithium-ion batteries by pyrometallurgy process.