Abstract:

The process of carbon thermal reduction-CO₂ water immersion was used to preferentially extract lithium from the cathode materials of spent ternary lithium ion batteries. The variables were changed individually such as roasting temperature, roasting duration, effective carbon addition, water leaching duration, solid liquid ratio, CO₂ flow rate and countercurrent water washing order to investigate the effects on the leaching rate of metal elements. When roasting temperature was 700℃, roasting time was 120min, effective carbon addition(75.56% carbon powder) was 14% (weight), liquid solid ratio was 10mL/g, water leaching time was 180min, CO₂ flow rate was 100mL/min and three stage countercurrent water washing, the leaching rate of lithium could reach 96.31%, and the leaching rates of cobalt, nickel and manganese metals were all lower than 0.1%. This process was applicable to different types of NCM batteries. In addition, the phase changes before and after carbothermal reduction were investigated by XRD, TEM and SEM-EDS.

Key words: waste ternary lithium ion batteries, carbothermal reduction, priority lithium extraction, leaching rate

摘要：

对废旧三元锂离子电池正极材料采用碳热还原-通二氧化碳水浸的工艺进行优先提锂。本文采用单一变量法探究焙烧过程中焙烧温度、焙烧时长、有效加碳量及水浸过程中水浸时长、水浸固液比、二氧化碳流量、逆流水洗级数等参数改变带来的金属元素浸出率的影响。在焙烧温度700℃、焙烧时长120min、有效加碳量（75.56%含碳量的炭粉）为14%（质量分数）、液固比10mL/g、水浸时长180min、二氧化碳通入量100mL/min、三级逆流水洗的最佳条件下，可以达到锂的浸出率为96.31%，钴、镍、锰金属的浸出率均低于0.1%。同时考察了该工艺对于不同型号的废三元锂离子电池回收的适用性，发现提锂效果均在90%以上，具有良好的原料适应性。此外，通过X射线衍射、透射电子显微镜、扫描电子显微镜探究碳热还原前后的物相变化。

关键词: 废旧三元锂离子电池, 碳热还原, 优先提锂, 浸出率