采用响应面优化酸浸法回收报废三元电池中有价金属的研究

Acid leaching optimization by response surface to recover valuable metals from spent ternary battery

为简化传统报废锂离子电池(LIBs)处理工艺,对报废镍钴锰三元(NCM)电池正极材料进行浸出处理,在单因素试验的基础上,利用响应面分析法分析浸出温度、抗坏血酸浓度、固液比和浸出时间对正极材料中Co、Li、Mn、Ni浸出率的影响。建立数学回归模型,分析因素间的交互作用。结果表明,各金属的回归方程模型均显著(p<0.05),R^2≥0.88,信噪比N>4,C.V.较低,可用于报废NCM电池中Co、Li、Mn、Ni浸出工艺的分析与预测,其中浸出温度和抗坏血酸浓度的交互作用对Li和Ni的浸出率影响最大。各金属浸出率的最佳工艺条件为:浸出温度69.26℃,抗坏血酸浓度1.24 mol/L,固液比31.30 g/L,浸出时间59.79 min。在此条件下,Co、Li、Mn、Ni浸出率分别为96.35%、92.53%、89.28%、56.32%。结合回归分析及可操作性原则,进行3次平行试验,试验结果与模型理论预测值接近。试验过程简单,处理方法对环境友好,有利于工业化生产。

The paper is aimed to leach the positive electrode sheets of the used-up nickel-cobalt-manganese ternary(NCM)batteries and simplify the LIBs treating process by using the lowselected acidity and reducibility of the ascorbic acid on the aluminum foil.For the said purpose,we have managed to separate the aluminum foil directly,and,then,at the same time,to leach the valuable metals in the active materials.To achieve the purpose,we have made an analysis of the influence of the leaching temperature,ascorbic acid concentration,the solid-liquid ratio and leaching time on the leaching rates of the cobalt,lithium,manganese and nickel in the cathode materials via the response surface method based on the single factor experiment.What is more,we have also analyzed the mechanism of the interactions among the factors so as to establish a series of mathematical regression equation models.The results of our experiments show that the regression equation models of all varieties of the metals are of great significance with p<0.05,and R^2≥0.88,but with their signal-to-noise ratio being greater than 4 and the CV value being low.The above said models can actually be endowed with the suitability to analyze and predict the leaching process of the cobalt,lithium,manganese and nickel in the spent NCM battery.In addition,the interaction between the leaching temperature and the extraction temperature as well as the ascorbic acid concentration may all have greatest effect on the leaching rates of lithium and nickel.As a result,the optimalized processing conditions for each metal leaching rate can be stated as follows:leaching temperature:69.26℃,the ascorbic acid concentration:1.24 mol/L;the solid-liquid ratio:31.30 g/L;the leaching time:59.79 min.If all the above said conditions can be strictly observed,it would be possible for the leaching rates of cobalt,lithium,manganese and nickel to reach the corresponding optimistic rates of 96.35%,92.53%,89.28%,and 56.32%,respectively.Thus,combined with the regression analysis and operational principle,it would be possible to carry out the following 3 parallel experiments so as to make the leaching rates of cobalt,lithium,manganese and nickel so high as up to 96.78%,92.75%,89.91%and 56.83%,respectively,which should be regarded as close to the theoretical forecast of the model.Thus,it can be concluded that,the research process we have proposed is simple,while the treating method is friendly to the environment and therefore beneficial for the practical industrial production.