【作者】 张小娟；

【导师】 李鑫钢；

【作者基本信息】 天津大学 ， 环境化工， 2010， 博士

【摘要】 随着社会经济的迅速发展,电子产品的更新速度不断加快,给环境保护和资源回收带来了极大的压力。作为电子产品主要组成部分的线路板具有危害性和资源性的双重特点,开展有关废弃印刷电路板回收处理技术的研究是热点问题,特别是环境污染成为亟待解决的问题。本论文以废弃线路板为研究对象,将废弃线路板破碎后,采用多种检测手段分析废弃线路板组成,确定其资源特性。绘制了铜、铁、锌、镍、锡的水系Eh-pH图和铜、锌、镍的氨系Eh-pH图,并对金属浸出过程进行了热力学分析。结果表明在合适的pH值和电位范围内,铜、铁、锌、镍、锡可用酸浸出,酸浓度的增大会促进金属浸出;铜、锌、镍可与氨在氧气加压的条件下形成络合离子而选择性地浸出,氨浓度的增大和氧压的增大会促进金属浸出。提出并研究了废弃电子线路板的盐酸-氯化铜三段浸出工艺过程,确定了较为适宜的工艺条件。第一段采用1.0mol/L盐酸作为浸出剂,锌、铁、镍的浸出率分别为99.99%、92.14%和82.5%;第二段采用1.8mol/L盐酸作为浸出剂,锡的浸出率为99.94%,锡的浸出过程由表面化学反应控制,遵循“未反应核减缩型”的表面化学反应控制的动力学规律,其反应活化能为42.7kJ/mol;第三段采用氯化铜为浸出剂,铅的浸出率为99.92%,铅浸出过程由表面化学反应控制,符合一级反应速率,其反应活化能为44.8kJ/mol。研究了电子线路板的氨水-碳酸铵-氧气选择性浸出过程,确定了较佳的工艺条件。在此工艺条件下,锌、铜、镍的浸出率分别为100%、99.39%和65.74%。铜浸出过程由扩散控制,其反应活化能为14.68kJ/mol。采用国产萃取剂LK-C2对浸出液中的金属进行萃取分离过程的研究,铜、铁、镍的萃取率分别为99.98%、96.14%和99.35%;以H₂SO₄为反萃剂研究了反萃过程,铜、铁、镍的反萃率分别为97.51%、99.18%和98.31%,取得了很好的分离效果。基于废线路板的复杂性和多样性,提出了不同的工艺流程,处理回收废线路板中的金属,本文的复合工艺具有较强的实用性。更多还原

【Abstract】 Nowadays with the rapid development of science and technology, electronic equipments are frequently upgraded, which leads to a significant increase of waste electric and electronic equipments. Because of the double characteristics with harmfulness and resource of discarded printed circuit boards （PCBs） ,which has high metal content, it is important to develop an economical, effective and environmental friendly technology for recycling metal from PCBs.The composition of the waste PCBs is analyzed. The results show that waste PCBs contain valuable metals which are important for economy and environmental protection to recover. The potential-pH equilibrium diagram for the system of Cu, Zn, Fe, Ni and Sn in water and ammonia were drawn to analyze the process of oxidative ammonia leaching from thermodynamics. The results show that leaching of Cu, Zn, Fe, Ni and Sn can be leached by acid at the appropriate pH range and potential range. The leaching will be enhanced by increasing the amount of acid. Cu, Zn and Ni can be leached with the formation of complex ions at the appropriate pH range and potential range. The leaching will be enhanced by increasing the amount of ammonia and oxygen pressure.Three-stage leaching using HCl-CuCl₂ is studied. The optimal conditions are confirmed.1.0mol/L HCl is used as leachant for the first stage. The extraction of Zn, Fe and Ni is 99.99%, 92.14% and 82.5% respectively. 1.8mol/L HCl is used as leachant for the second stage. The extraction of Sn is 99.94%. The dissolution of Sn is controlled by a surface reaction, and the activation energy of Sn amounts to 42.7kJ/mol. CuCl₂ is used as leachant for the third stage. The extraction of Pb is 99.92%. The dissolution of Pb is controlled by a surface reaction, and the reaction obey the rule of first-order reacting rate. The activation energy of Pb amounts to 44.8kJ/mol.The ammonia/ammonium leaching under oxygen pressure for PCBs was carried out to investigate the extraction behavior of copper, zinc and nickel. The optimal conditions are confirmed. Under optimum leaching conditions 100% Zn, 99.29% Cu and 65.74% Ni were effectively recovered with almost no leaching of Sn, Pb and Fe. The dissolution of Cu is controlled by diffusion, and the activation energy of Cu amounts to 14.68kJ/mol.Homebred extractant LK-C2 is used to separation and recover metals in leaching solution. The extraction of Cu, Fe and Ni is 99.98%, 96.14% and 99.35% respectively. H₂SO₄ is used as stripping extractant. The stripping rate of Cu, Fe and Ni is 97.51%, 99.18% and 98.31%. Cu, Fe, Ni and Zn can be separated by using LK-C2 effectively.Considering the complexity and variety of waste PCBs, different technics flows are given to recover metals from waste PCBs.更多还原