【作者】 李丹；

【导师】 潘军青；

【作者基本信息】 北京化工大学 ， 化学， 2022， 硕士

【摘要】 近年来随着交通、通讯、应急设施和新能源储能的快速发展,铅蓄电池以其成本低、性能稳定、安全性好等优点,在上述领域获得了广泛应用。由于铅蓄电池通常只有3-5年的使用寿命,未来几年将面临大量铅蓄电池的报废和回收问题。近年来随着原生铅资源的逐渐减少,因此回收废铅蓄电池中的铅资源不仅可以解决铅蓄电池制造的原料问题,而且有利于铅污染物的有效控制。现有废铅蓄电池的回收工艺主要分为:火法工艺和湿法工艺。火法工艺在高温回收过程中,会释放大量铅粉尘以及硫氧化物,对周边环境造成较严重的二次污染。因此从废铅膏中湿法回收铅是相对清洁的处置工艺。为了响应国家提倡的双碳经济问题,将废铅蓄电池直接回收为氧化铅是更低碳的回收工艺。然而现有回收氧化铅工艺存在回收成本高、产品纯度低和母液处理量大等缺点,阻碍了工业化开发过程。针对上述问题,本文提出了一种预脱硫废铅膏焙烧制备的粗氧化铅通过氨基酸定向络合浸出-含铅络合物碳化分离,以及碳酸铅热分解工艺制备α-氧化铅,并回收碳化和热解过程产生的氨基酸和二氧化碳,构成氨基酸-二氧化碳双循环回收高纯度氧化铅新工艺,实现了废铅蓄电池低成本绿色回收过程。研究内容如下:(1)预脱硫废铅膏焙烧制备粗氧化铅采用碳酸钠对废铅膏进行脱硫转化,分别通过碳酸钠浓度、搅拌强度、反应时间和反应温度四个因素对其进行研究。在最佳条件下,废铅膏的脱硫率达到99.01%,且根据动力学结果表明,脱硫过程符合化学反应控制过程。并根据XRD、TG-DTA分析结果,确定粗氧化铅的焙烧温度为570℃。(2)氨基酸定向循环浸出和二氧化碳碳化制备高纯度碳酸铅在浸出过程中,利用氨基酸特有的空间结构和定向络合特性,通过研究氨基酸浓度、反应温度、反应时间、搅拌强度对浸出率的影响以及反应过程中的pH变化,阐明含铅组分在氨基酸溶液中的选择性浸出和定向络合机制。在最佳条件下,铅浸出率达到98.65%,并根据XRD、mapping-EDS分析确定了杂质元素的存在形式和迁移规律。在碳酸化过程中,研究了碳化温度、碳化时间、陈化时间和搅拌强度对铅析出率和碳酸铅形貌的影响,在最佳条件下,铅的析出率达到99.32%,碳酸铅形貌呈六方双锥状结构。根据ICP结果分析,碳酸铅的纯度达到99.99%。此外,氨基酸溶液在五次循环浸出过程中,铅的总回收率均保持在97.56%左右。(3)碳酸铅可控热分解回收高纯度α-氧化铅和二氧化碳主要研究了焙烧温度和焙烧时间对氧化铅定向结晶过程的影响,当焙烧温度为400℃,时间为40 min时,制备出纯度可达99.99%的α-氧化铅,并根据计算得到,杂质钡和铁元素的总去除率为99.99%和93.59%。并在此基础上,研究了二氧化碳的循环利用技术,当碳酸铅焙烧量为25 g以上时,二氧化碳的循环率稳定在97.51%。更多还原

【Abstract】 In recent years,with the rapid development of transportation,communication,emergency facilities and new energy storage,lead-acid batteries have been widely used in the above fields because of their low cost,stable performance,and good safety.Since lead-acid batteries usually have a service life of 3-5 years,a large number of lead-acid batteries will be scrapped and recycled in the next few years.Rencently,with the decreasing of primary lead resources,the recovery of lead resources from spent lead-acid batteries can not only solve the problem of raw materials for lead battery manufacturing,but also facilitate the effective control of lead pollutants.The existing recycling process of spent lead-acid battery can be divided into pyrometallurgical process and hydrometallurgical process.A large amount of lead dust and sulfur oxides will be released during the high-temperature recovery of the pyrometallurgical process,causing serious secondary pollution in the surrounding environment.Therefore,hydrometallurgical recovery of lead from spent lead paste is a relatively clean disposal process.In response to the dual-carbon economy advocated by the state,it is a lower-carbon recycling process to recover lead oxide directly from the spent lead-acid batteries.However,the existing hydrometallurgical process has some disadvantages,such as high recovery cost,low product purity and large amount of mother liquor treatment,which hinder the industrial development process.Given the disadvantages of above process,this paper proposes a low-cost green recycling process for spent lead-acid batteries.The crude lead oxide was prepared by roasting pre-desulfurized spent lead paste,and the lead-containing complex leachate was obtained by directional complexation reaction with amino acid,and then it was carbonized and separated to obtain lead carbonate,which then was thermally decomposed to prepareα-PbO.And in this process,a new process of amino acid-carbon dioxide double-cycle recovery of high-purity lead oxide was formed.The research content is as follows:(1)Crude lead oxide was prepared by roasting pre-desulfurized spent lead pasteThe desulfurization conversion of spent lead paste was carried out with sodium carbonate,and it was studied by four factors:sodium carbonate concentration,stirring intensity,reaction time and reaction temperature.Under the optimal conditions,the desulfurization rate of spent lead paste reached99.01%,and the kinetic results showed that the desulfurization process conforms to the chemical reaction control process.And according to the analysis results of XRD and TG-DTA,the calcination temperature of crude lead oxide was determined to be 570 C.(2)High-purity lead carbonate was prepared by amino acid directional cyclic leaching and carbon dioxide carbonizationIn the process of leaching,the selective leaching and directed complexation mechanism of lead components in amino acid solution was elucidated by studying the influence of amino acid concentration,leaching temperature,leaching time,and agitation intensity on the leaching rate and pH change during the reaction process,using the unique spatial structure and directed complexation characteristic of amino acids.Under the optimal conditions,the leaching rate of lead reached 98.65%,and the existence form and migration rules of impurity elements were determined by XRD and mapping-EDS analysis.In the process of carbonation,the influences of carbonization temperature,carbonization time,aging time and stirring intensity on the precipitation rate of lead and the morphology of lead carbonate were studied.Under the optimal conditions,the precipitation rate of lead was 99.32%,and the morphology of lead carbonate was a hexagonal biconical structure.According to the ICP results,the purity of lead carbonate reached 99.99%.In addition,the total recovery rate of lead was maintained at about 96.98%during the five-cycle leaching process of the amino acid solution.(3)High purityα-PbO and carbon dioxide were recovered by controlled thermal decomposition of lead carbonateThe influences of calcination temperature and calcination time on the directional crystallization process of lead oxide were mainly studied.When the roasting temperature was 400℃ and the time was 40 min,α-PbO with a purity of 99.99%was prepared.According to the calculation,the total removal rate of impurity barium and iron elements reached 99.99% and 93.59%.On the basis,the recycling technology of carbon dioxide was studied.When the roasting amount of lead carbonate was more than 25 g,the circulation rate of carbon dioxide was stable at 97.51%.更多还原