(1. 中南大学 化学化工学院,长沙 410083;
2. 中南大学 有色金属资源化学教育部重点实验室,长沙 410083)
摘 要: 以废旧锂电池正极条为阴极,以铅板作阳极,在稀硫酸溶液中,电解浸出正极材料中的钴,从热力学和动力学两方面对钴的电解浸出过程进行研究。实验及热力学数据分析表明:LiCoO2主要通过Co(OH)3还原浸出得到Co2+,考查浸出温度和时间表明在电解前期5~30 min电解浸出由缩核模型的化学反应过程控制,浸出率α与时间t满足未反应核收缩模型1-(1-α)1/3=Kt,其表观活化能为7.32 kJ/mol;中期是混合控制;后期75~180 min符合内扩散控制模型1-2α/3-(1-α)2/3=Kt,表观活化能17.05 kJ/mol。浸出液中的铝主要是铝箔表面氧化铝层不受阴极保护而溶于硫酸溶液,正极材料从铝箔上剥离与氧化铝层的溶解有关,剥离时间影响钴的浸出率。
关键字: 废旧锂电池;电解浸出;热力学;动力学
(1. College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Metal Resource Chemistry, Ministry of Education Hunan,
Central South University, Changsha 410083, China)
Abstract:Cobalt in spent lithium-ion battery was leached out in sulfuric acid using the cathode bar as cathode and lead plate as anode. And the process was studied in thermodynamics and dynamics two aspects. The results show that LiCoO2 is reductive leached Co2+ by Co(OH)3 through compared experiments and thermodynamic data. Through theoretical analysis and experimental research, the process is controlled by chemical reaction process of shrinking core model in the early 5-30 min, leaching rate α and time t satisfy inner diffusion the unreacted core shrinking model equation 1-(1-α)1/3=Kt, apparent activation energy is 7.32 kJ/mol. The middle stage is hybrid control. And the last conforms with the internal diffusion model, where α and t suit to 1-2α/3-(1-α)2/3=Kt, and the apparent activation energy is 17.05 kJ/mol. Al3+ in leach solutions comes from aluminium oxide dissolved in liquid without protection. The cathode material peeled from aluminum foil is related to the dissolution of aluminium oxide, which affects the leaching rate of cobalt.
Key words: spent lithium-ion battery; electrolytic leaching; thermodynamics; kinetics