废旧磷酸铁锂电极粉中Li和Fe同步浸出动力学研究

Study on Kinetics of Simultaneous Leaching of Li and Fe from Spent Lithium Iron Phosphate Electrode Powder

废旧磷酸铁锂中有价组分高值化回收和利用具有资源循环和环境保护双重意义。对废旧磷酸铁锂电极粉的浸出过程进行了条件优化和动力学研究,系统探究了硫酸浓度、反应温度、电极粉粒径及搅拌速度对Li和Fe浸出行为的影响,并阐明了Li和Fe的浸出动力学机理。结果表明:在硫酸浓度2.5 mol/L、浸出温度75℃、粒径0.14 mm左右、搅拌速率400 r/min的条件下,Li和Fe的浸出率均在99.8%以上。动力学研究表明浸出过程受外扩散控制,浸出动力学方程符合Avrami模型,浸出过程中Fe和Li的表观活化能分别为11.03、8.45 kJ/mol。废旧磷酸铁锂电极粉中Li和Fe的浸出动力学机理结果可为有价元素的同时提取提供理论指导。

The high-value utilization of valuable components in spent lithium iron phosphate has the dual significance of resource recycling and environmental protection.The condition optimization and kinetics of the leaching process were studied for spent lithium iron phosphate electrode powder.The effects of sulfuric acid concentration,reaction temperature,electrode powder particle size and stirring speed on the leaching behavior of Li and Fe were systematically investigated,and the leaching kinetic mechanism of Li and Fe was clarified.The results show that the leaching rate of Li and Fe is above 99.8%under the conditions including sulfuric acid concentration of 2.5 mol/L,leaching temperature of 75℃,particle size of 0.14 mm,and stirring speed of 400 r/min.The kinetics indicate that the leaching process is controlled by external diffusion,and the leaching kinetics equation is consistent with Avrami model.The apparent activation energy of Fe and Li during leaching process is 11.03 kJ/mol and 8.45 kJ/mol,respectively.This study can provide theoretical guidance for simultaneous extraction of valuable elements from spent lithium iron phosphate electrode powder.