废弃印刷线路板熔融盐气化及金属回收实验研究

GIEC OpenIR > 中国科学院广州能源研究所

	废弃印刷线路板熔融盐气化及金属回收实验研究
其他题名	Experimental study on molten salt gasification and metal recovery of waste printed circuit boards
	李飞
导师	陈勇
	2007-06-08
学位授予单位	中国科学院广州能源研究所
学位授予地点	广州能源研究所
学位名称	博士
关键词	溴化环氧树脂印刷线路板熔融盐气化金属回收
摘要	随着电子和信息行业的迅速发展，以及电子电气产品的生命周期日益缩短，随之而产生的废弃印刷线路板的数量也十分巨大。印刷线路板成分复杂，通常含有30%的有机树脂，30%的难熔氧化物以及大约40%的金属，其中铜的含量约占20%，具有较高的资源回收价值。同时印刷线路板中含有的重金属（铅、汞、铬、镉等）和含溴阻燃剂对环境具有潜在危害，处理不当将对人类和环境造成严重影响。熔融盐气化技术利用熔融盐的高传导率和强氧化性，为有效的分解线路板中的树脂，破除有机含溴阻燃剂，防止有机污染物的排放提供了可能的技术途径。同时，熔融盐气化技术将印刷线路板中的金属和无机物滞留在熔融盐内，通过对熔融盐的进一步处理可以有效的回收金属。本文在广东省自然科学基金的资助下，开展印刷线路板熔融盐气化和金属回收实验研究，考察印刷线路板熔融盐气化过程的热分解特性和产物特性，溴迁移脱除规律以及金属分布回收规律。首先采用TG-FTIR联用技术和Py-GC/MS技术对溴化环氧树脂印刷线路板的热分解过程进行了在线分析，研究结果表明：溴化环氧树脂印刷线路板热解过程首先发生溴化结构的裂解，主要产物包括CO、丙酮、溴甲烷、溴苯酚、2，6－二溴苯酚等，非溴化结构的裂解发生在较高的失重温度，生成苯酚，p-异丙基苯酚、p-异丙烯基苯酚、邻甲基苯酚、对甲基苯酚等酚类物质。在小型熔融盐反应器中考察两种混合熔融盐对于印刷线路板热分解过程和产物特性的影响。研究结果表明熔融盐的存在可以大幅提高热解过程碳的气相转化率，减少液体产物产率。在未添加熔融盐的条件下，热解终温为900℃时，碳的气相转化率为35.94%，液体产物产率为28.29%。添加 NK (71%Na2CO3－29%K2CO3) 盐后，热解终温为700℃时，碳的气相转化率为40.76%,液体产物产率为22.34%。添加NN (8.3%Na2CO3－91.7%NaOH) 盐后，碳的气相转化率达到59.36%，液体产物产率减少为6.88%。元素分析结果表明熔融盐的存在可以减少固体残渣中的含碳量，而液体产物的H/C比为1.12～1.20。在熔融盐气化炉中进行印刷线路板气化实验，实验结果表明印刷线路板在熔融盐气化炉内裂解主要气体产物为H2和CO，两者的体积占产气总体积的70％，随着空气当量比增加，气体产率和碳转化率随之增加，产气热值随之减少，气化效率先增加然后减少，在20％当量比达到最大值94％。液体产物的主要成分为苯酚、2-甲基苯酚、萘等，表明线路板在熔融盐气化炉内的反应过程中，苯环结构上的长链烷烃脂肪烃支链得到脱除，苯基C6H5-O的断裂得到加强，同时发生部分芳构化反应。对溴化环氧树脂印刷线路板熔融盐气化和管式炉热解过程中的溴分布规律进行研究，结果表明气化过程中，熔融盐吸收的溴含量占物料含溴量的73.8％，而气体产物的含溴量仅占物料中含溴量的0.006%。而印刷线路板管式炉热解后，物料中的溴主要分布在液体产物中，热解温度为500℃时，液体产物中测得的溴占物料含溴的85.1％。对印刷线路板熔融盐气化过程中金属在熔融盐内的滞留和分布情况进行考察。结果表明90％以上的Cu、Al、Ca、Cd、Co、Mg、Sb、Sn、Zn等金属滞留在熔融盐内部。滞留的金属大部分分布熔融盐底部，Al、Cu、Co、Sb、Sn在熔融盐纵向底部的3、4层中的分布量达90％以上；Mg、Pb和Se在底部3、4层的分布量也在70％以上。利用金属和非金属成分在不同纵向高度上的分布区别，可以回收得到富集度较高的金属富集体。如纵向4层的总金属含量达到92.76％，且其中的铜含量达到78.06％，Al含量达到9.89％。最后对印刷线路板的熔融盐气化反应过程建立反应动力学模型，并利用模型对印刷线路板熔融盐水蒸气和二氧化碳气化反应体系进行模拟计算，计算结果表明：当水蒸气/物料质量比为0.25时，气化效率达到最大值89.7％，H2体积含量达到51.6％，CO体积含量达到36.8％，气体热值为17630kJ•m-3。当二氧化碳/物料质量比为0.55时，气化效率达到93.2％，CO体积含量达到65.7％，H2体积含量达到26.8％，气体热值为16270kJ•m-3。
其他摘要	Along with the rapid development of electronic information industry and the shorter and shorter lifecycle of electric and electronic equipments, the quantity of waste printed circuit boards (PCB) increases largely. Waste PCB contains substantial quantities of reusable materials and significant quantities of hazardous substances such as heavy metals, and brominated organic compounds. Molten salt gasification technology utilizing the high thermal conductivity and strong oxidizing property, provide a technically possiblility to decompose the polymers in PCB effectively, to destroy the brominated organic compounds completely and to prevent the release of organic contaminents. During the gasification process of PCB, the metal contents are detained in molten salt, and can be recovered by dealing with the salts. The molten salt gasification characterstics and metal recovery process of PCB were studied in this persent paper. Firstly the thermal decomposition process of a kind of brominted epoxy resin (BER) printed circuit boards was investigated by TG-FTIR and Py-GC/MS. The experimental results show that during the thermal decomposition process of BER, the brominated parts firtly degraded. The degradation of unbrominated parts happened at higher temperature and the pyrolysis products contained phenol, p-isopropylphenol, p-isopropenylacetylphenol, o-methylphenol and p-methylphenol. The effect of two different kinds of binary eutectic salts on the pyrolysis processes and pyrolysis products characterstics of PCB were studied with a bench scale molten salt reactor. The results show that the binary eutectic salts can decrease the liquid product yield. Consequently, the carbon conversion rate from PCB to gas products is increased greatly. The gasification experiment of PCB was carried out in a molten salt reactor. The results show that the main gas product of PCB molten salt gasification is H2 and CO, which accounts for 70vol% of total gas yield. The gas yield and carbon conversion rate increases with the equivalence ration. Along with the increase of the equivalence ration, the gas heating value decreaseed, and the gasification efficiency increased first and then decreased, which reach maximum 94% when the equivalence ration is 20%. The behavior of bromine during molten salt gasification were investigated. The results show that 73.8wt% bromine of feedstock has been neutralized and absorbed by molten salt, and only 0.006wt% bromine of feedstock was tested in gas products. The detention and distribute behavior of metal during molten salt gasification of PCB was investigated. The results show that over 90% Cu, Al, Ca, Cd, Co, Mg, Sb, Sn, Zn was detained in molten salt. the metallic fraction could be recycled with collecting and dealing with the bottom layers of molten salt. For example, the materials recycled from the bottom layer contained 92.76wt% metal, including 78.06wt% Cu and 9.89wt% Al. Finally, a prediction model on the molten salt gasification of PCB was proposed based on reaction kinetics. With the kinetics model, the steam and CO2 gasification process of PCB in molten salt were calculated.
页数	125
语种	中文
文献类型	学位论文
条目标识符	http://ir.giec.ac.cn/handle/344007/3995
专题	中国科学院广州能源研究所
推荐引用方式 GB/T 7714	李飞. 废弃印刷线路板熔融盐气化及金属回收实验研究[D]. 广州能源研究所. 中国科学院广州能源研究所,2007.

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