丙二酸-抗坏血酸协同浸出废旧三元电池有价金属的方法

Synergistic leaching of valuable metals from waste ternary batteries with malonic acid and ascorbic acid

近年来,对锂离子电池的需求急剧增长,但正极中的诸多基本组成元素,如锂、钴、镍价格昂贵且对外进口依赖严重。目前,大多数湿法冶金浸出方法都是基于“无/有机酸+H_(2)O_(2)”体系,该方法存在环境污染、安全隐患和效率问题。提出一种新的环保、安全、高效的浸出工艺,以丙二酸和抗坏血酸为浸出剂和还原剂,最佳条件为:丙二酸浓度0.4 mol/L、抗坏血酸浓度0.2 mol/L、固液比30 g/L、浸出温度50℃、浸出时间50 min,在最佳条件下,锂、镍、钴、锰的浸出率均大于95%。动力学拟合验证结果表明,浸出过程符合“缩芯模型”,且表观活化能低于“有机酸+H_(2)O_(2)”的值;故抗坏血酸的加入能够有效促进丙二酸浸出正极材料中的有价金属,提高浸出效率;红外光谱、XRD结果表明,浸出过程中丙二酸与过渡金属的配位形式为C_(3)H_(2)O_(4)M(M为过渡金属Ni、Co、Mn)。

In recent years,the demand for lithium-ion batteries(LIB)has grown rapidly,but many basic elements in the positive electrode,such as lithium,cobalt,and nickel,are expensive and heavily dependent on imports.At present,most hydrometallurgical leaching methods are based on the use of an“in/organic acid+H_(2)O_(2)”system,but there are environmental pollution,safety hazards,and efficiency issues.Therefore,this study proposes a new environmentally friendly,safe,and efficient leaching process using malonic acid and ascorbic acid as leaching and reducing agents.Under the optimal conditions:malonic acid concentration of 0.4 mol/L,ascorbic acid concentration of 0.2 mol/L,solid-liquid ratio of 30 g/L,leaching temperature of 50℃,and leaching time of 50 minutes;the leaching rates of lithium,nickel,cobalt,and manganese are all more than 95%.The kinetic fitting validation results indicate that the leaching process conforms to the“shrinking core model”and the apparent activation energy is lower than the previous values of“organic acid+H_(2)O_(2)”;therefore,the addition of ascorbic acid can effectively promote the leaching of valuable metals from positive electrode materials with malonic acid,thereby improving the leaching efficiency;the infrared spectrum and XRD results indicate that the coordination form between malonic acid and transition metals during the leaching process is C_(3)H_(2)O_(4)(M is transition metals Ni,Co,Mn).