硫酸——甘蔗渣体系浸出提取废旧锂离子电池中的钴

Leaching cobalt from waste lithium-ion batteries using sulfuric acid-bagasse system

为回收废旧锂离子电池中的有价值金属,采用硫酸—甘蔗渣体系进行酸浸,将钴从废旧锂离子电池电极材料中浸出,并探讨了甘蔗渣对钴浸出效果的影响及反应机理。研究表明:甘蔗渣作为还原剂参与浸出反应,甘蔗渣中的醛基以及反应后的中间产物RCOO.H_2,都可与Co^(3+)反应,将其还原成Co^(2+),替代了价格昂贵且利用率低的H_2O_2,提高了钴的浸出率。钴的浸出反应符合有收缩的未反应核模型,反应前期,表观活化能为22.98 k J/mol;反应后期,表观活化能为38.31 k J/mol。在浸出温度90℃,浸出时间1 h,硫酸浓度2 mol/L,液固比150∶1,甘蔗渣粒径0.3 mm,甘蔗渣添加量0.5 g的最优条件下,钴的浸出率达95.38%。

In order to recover valuable metals in waste lithium ion batteries,a sulfuric acid-bagasse system was used for leaching cobalt from waste electrode materials of lithium-ion batteries in this study. The leaching efficiency and reaction mechanism of the sulfuric acid-bagasse system were investigated. The experimental results demonstrated that sugarcane residues were involved in leaching reaction as a reducing agent. The aldehyde groups in the bagasse and the reaction intermediates such as RCOO. H_2 could replace H_2O_2,which was of high cost and low utilization rate,to reduce Co^3＋ to Co^2＋,and increase the leaching efficiency. The cobalt leaching reaction wasconsistent with the reaction less core-shrinking model, the apparent activation energy was22. 98 k J·mol^-1 in the early stage of reaction,and 38. 31 k J · mol^-1 in the later. The optimal leaching temperature,leaching time,sulfuric acid concentration,the ratio of solid to liquid,bagasse size,and the dosage of bagasse were 90 ℃,1 h,2 mol · L^（-1）,150 ∶ 1 m L·g^（-1）,0. 3 mm,and0. 5 g respectively. The cobalt leaching efficiency was up to 95. 38% under the optimum condition.