| 题名 | 废旧阴极射线管锥玻璃中铅的氯化回收技术研究 |
| 作者 | 阿尔斯·艾尔扎提 |
| 学位类别 | 硕士 |
| 答辩日期 | 2014-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 张付申 |
| 关键词 | 阴极射线管 锥玻璃 氯化挥发 无害化 铅回收 Chloride volatilization Lead recovery Cathode ray tube Funnel glass Detoxification |
| 其他题名 | Recovery of Lead from Waste Cathode Ray Tube (CRT) Funnel Glass by Chlorinating Volatilization Process |
| 学位专业 | 环境工程 |
| 中文摘要 | 废弃阴极射线管（CRT）是电子废弃物的重要组成部分，其资源化利用是目前电子废弃物处理的难点和热点。CRT锥玻璃中含有大量的铅，现行的回收利用方法主要有湿法和火法两种，其中湿法以强酸浸出为主，在处理的过程中会产生大量的难处理酸性废水，而火法则容易造成铅在环境中的扩散。因此，研究简单、实用、环保的CRT锥玻璃中铅的回收方法，对于废弃CRT无害化处理和循环利用具有重要的实际意义。本论文以典型的废弃彩色电视机CRT锥玻璃为原材料，采用氯化挥发法分离回收铅，通过追踪氯化挥发处理产物中的典型重金属（Pb、K、Ca、Na、Mg、Al）的分布特征，为高效、环保地无害化及回收阴极射线管中的铅提供理论依据和技术支撑。获得的主要研究结果如下： 1、通过对废弃CRT锥玻璃中铅等重金属氯化反应的热力学计算，发现氯化钙和氧化铅的直接氯化反应在1100℃时才开始发生，而玻璃中的二氧化硅倾向于与氯化剂中的钙生成稳定的硅酸钙晶体，促进氯化反应在较低温度下的进行，此时体系中的氧化铅能更好的转化成氯化铅。如果采用氯化钠等单价碱金属氯化物作为氯化剂，则氯化剂很容易和氯化铅一起挥发出来，影响铅的回收效果；而碱土金属钙等多价金属的氯化物则以硅酸盐的形式稳定的存在于固体残渣中，有利于铅的氯化挥发。 2、研究发现，氯化挥发法是无害化处理废弃CRT锥玻璃的有效方法，氯化钙是一种合适的氯化剂，反应过程中铅的去除率随着温度的升高而增大，在1000℃时达到最大值。另外，铅去除率随着反应时间的延长而增大，在1.0h时达到最大值。氯化挥发法和真空条件结合能够获得更好的无害化处理效果。最佳的铅去除率是在1000℃，气压为600±50Pa时，反应1.0h。铅的去除率达到99.3%，铅的去除效果相当显著。 3、通过追踪反应过程中铅的归趋，发现锥玻璃中95.6%的铅被反应系统中的冷凝回收系统回收，这些氯化铅可以再次提纯后制备成纯度为97.0%的工业级氯化铅产品。反应过程中0.9%的铅随着载气排出，可以在尾气处理装置中俘获，尾气排放符合国家的相关标准（GB-25466-2010）。残渣中铅的残余量虽然为总含铅量的3.5%，但经TCLP浸出实验鉴定，其溶出浓度为1.69-2.11 mg/L，远低于原始材料中的18.8mg/L，达到TCLP法规定的5.0mg/L的鉴别标准。反应后残渣的主要晶相为钙硅石，在涂料、塑料等行业都有一定的应用价值。 |
| 英文摘要 | Waste cathode ray tube (CRT) is an important part of waste electrical and electronic equipment (WEEE) in the world. The recovery of waste CRT glass is becoming one of the biggest issues of WEEE recovery. Leaching process and pyrometallurgical process are the mainly two methods of current recycling methods of CRT glass. Leaching process mostly utilizes strong acid, which leaves plenty of waste water behind after treatment. And pyrometallurqical process lead to lead spread into environment easily. So the recovery of waste CRT by simply, useful and environmental friendly process can reduce the environmental risk and increase the material recovery rate at the same time. In this study, typical type of waste CRT glass from color television set was investigated. The wide used metallurgy technique, which is chlorination volatilization, was used in recovery of waste CRT glass for the first time. By investigating the metal (Pb、K、Ca、Na、Mg、Al) containing characters of the product from the process, the theoretical basis and technical support of recovering waste CRT glass effectively and environmental friendly were investigated. The major research results were as follow. 1. According to thermodynamic calculation, CaCl2 could not react with PbO when the temperature was lower than 1100°C in the absence of SiO2. Lead chloride was formed by the replacement of lead with calcium in the silicate glass phase. Negative ΔG values were obtained at a large range of temperatures, implying that lead was efficiently volatile in the presence of CaCl2. Lead, sodium and potassium chlorides were released from the glass matrix at relatively low temperature because of the strong tendency of calcium to form silicates. The multivalent metal, such as calcium, magnesium, and aluminum, generally left inside the residues. 2. It was proofed that the effect of recovering waste CRT glass by chlorination volatilization process has achieved the expectation. During the experiment, CaCl2 was demonstrated as the appropriate chlorating agent. The evaporation rate of lead increased with the increase of temperature. Optimal value was achieved at 1000℃, after that the increase of lead evaporation rate is not obvious. As the evaporation rate of lead increased with the increase of reaction time, the optimal value was achieved at 1h. The vacuum condition is helpful to the chlorination volatilization process. And different between Ar and Air condition is not obvious. The optimum operation temperature, holding time and system pressure were 1000°C, 1h, 600±50Pa, respectively. The evaporation rate of lead is 99.3%. 3. By tracking the lead during the process, it was found that 95.6% of lead was recovered by the cooling system. These lead was made as lead chloride product of 97.0% purity. After purification, 94.9% of lead as the final product was collected from the cooling system. 0.9% of lead was bring out by the exhausted off-gas, being captured by tail gas treating unit, whose concentration was below the limited value specified by GB-25466-2010 standard for a new industrial facility (8.0 ppb). 3.5% of lead was left in the residue. Before the detoxification, the waste CRT glass was defined as hazardous waste. The TCLP leaching concentration of Pb was 18.8 mg/L. After the treatment, the residues are meet specifications to the non-hazardous waste, as the previous research reported, whose leaching density of TCLP test is only 1.69-2.11 mg/L lower than the TCLP lead threshold by USEPA (5 mg/L). This result indicates that calcium silicate mineral in the residue could convert into valuable resource safely. The residue of this study is mainly made of wollastonite, which is a novel environmental friendly way to provide wollastonite for industrial manufacture. |
| 公开日期 | 2015-06-12 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/13451]  |
| 专题 | 生态环境研究中心_固体废弃物处理与资源化实验室 |
| 推荐引用方式 GB/T 7714 | 阿尔斯·艾尔扎提. 废旧阴极射线管锥玻璃中铅的氯化回收技术研究[D]. 北京. 中国科学院研究生院. 2014. |
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