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题名: 基于机械化学法的PVC行业废汞触媒稳定化固化技术及应用研究
作者: 任亚峰
学位类别: 硕士
答辩日期: 2015-05
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 朱建新
关键词: 废汞触媒,机械化学法,固化稳定化,硫磺,环境风险,waste mercury chloride catalyst, Stabilization/Solidification, mechanochemical method, sulfur, environmental risk
其他题名: Mechanochemical Stabilization/Solidification of Waste Mercuric Chloride Catalyst Generated from Calcium Carbide-based PVC Industry
学位专业: 环境工程
中文摘要:     我国是世界上最大的电石法 PVC生产国,每年产生的废氯化汞触媒的数量在 1-1.5万吨之间,预计未来几年内将以  10%-15%的速率增加。废汞触媒中含有4%左右的氯化汞,属于特殊危险废物,具有浸出毒性和腐蚀性。目前,废汞触媒的回收利用率不到 1/3。本论文开展了机械化学法在废汞触媒稳定化固化应用中的可行性研究,阐明了废汞触媒机械化学稳定化机理。主要研究内容及成果包
括:
(1)当废汞触媒中氯化汞的含量为 5715 mg/kg时,将其与硫磺混合球磨120min后,汞的TCLP毒性浸出值低于0.2 mg/L,低于美国环保局所规定的最大允许值。然后,从球磨转速、球磨时间、球料比以及物料比等几个方面对机械化学法工艺参数进行了优化。得出最佳球磨参数为:球磨转速 550 rpm,球磨时间120min,球料比 40:1,废汞触媒与硫磺的比例为  1:8的情况下,可实现废汞触媒中
氯化汞的高效稳定化。
(2)对球磨样品进行了 SEP逐级提取实验,分析了球磨样品中汞的形态分布;根据逐级提取分析结果,汞最后以残渣态汞的形式存在,生物可利用性以及迁移性都大大降低;在球磨过程中,可溶可交换态、特殊吸附态、氧化结合态和有机结合态汞逐渐转化为残渣态;TCLP毒性浸出测试中浸出的汞主要来源于可溶可交换态和特殊吸附态汞。
(3)由于球磨后样品的是以粉末形式存在,本研究通过加入水泥使球磨样品固化,探讨了水泥加入对汞触媒和球磨稳定后汞触媒中汞的浸出特性的影响。对于触媒与硫磺的质量比为 1:1、1:4和  1:8的球磨稳定化样品,在加入水泥固化后,所有固化体汞的毒性浸出浓度低于 0.2  mg/L和国家危险废物污染填埋控制标准 0.25 mg/L。
(4)本部分采用等离子体全谱直读光谱仪、XRD、XPS和  ESR等仪器对球磨处理后样品的汞的存在形式进行表征,并对氯化汞在球磨过程中可能存在的化学反应进行了阐述。分析结果显示,废汞触媒和硫磺球磨之后有硫化汞形成,并且球磨过程形成的自由基和活性炭的存在有助于氯化汞和硫磺之间发生化学反应形成硫化汞。
    本研究结果显示,以硫磺为添加剂,机械化学法稳定固化电石法 PVC行业产生的废汞触媒具有实际应用的潜力。在本研究的基础上,可以考虑将机械化学法稳定固化废汞触媒的方法进行示范项目建设,为未来 PVC行业产生的大量废汞触媒的安全处理处置和无害化提供工程实践经验。
英文摘要:      China  is  the  largest   polyvinyl  chloride  (  PVC  )  producer.   In  China,  about 10,000-15,000 tons  of waste mercury  chloride catalyst, which  normally contains 4% HgCl2, were generated annually and the generating  volume will grow at the rate of 10 - 15%  over  the next  years. Waste  mercury catalyst  was  listed as  special hazardous waste with leaching toxicity and corrosivity,  and the recovery rate of waste catalyst is less   than    1/3.   In    this   research    work,   the    feasibility   of    mechanochemical stabilization/solidification  of waste  mercury  catalyst  generated  from  PVC industry was  researched  and  mechanochemical  stabilization   mechanism  of  waste  mercury catalyst was illuminated. The main achievements of this dissertation were as follows:
(1) When the concentration  of mercury in simulated  waste mercury catalyst was 5715 mg/kg, the  mercury leaching concentration of  mechanochemical treated sample was lower 0.2 mg/L  after milling with sulfur for  120 min. The experiment of  process parameter optimization  demonstrated that when  the rotation speed  was 550  rpm, the mass ratio  of ball  to reactant  was 40:1,  the mass  ratio of  waste mercury  catalyst to sulfur was 1:8,  the effective stabilization of  mercury in waste mercury  catalyst could be realized.
(2) Based on the result of SEP experiment for milled samples, mercury of soluble and exchangeable, specially sorbed,  oxide-bound and organic-bond were  transformed in  residual  mercury in  the  milling  process;  Finally,  more  than 99.9%  of  mercury existed as  residual fraction, which  is normally unavailable for  methylation due  to its very  low solubility  (10-54mol•L-1) and  low  mobility. The  correlativity  between the mercury distribution  derived from SEP  and the leaching  content of Hg  in TCLP test was analyzed. The mercury in TCLP leaching fraction  were mainly resulting from the mercury in the exchangeable and soluble and the specially sorbed fractions.
(3) Since waste mercury catalyst after milled with sulfur  existed as powder form, solidification  of   waste  mercury   catalyst  after  mechanochemical   treatment  using cement was investigated in this study.  For the mechanochemical stabilization samples with  the   mass   ratio  of   catalyst  to   sulfur  1:1,   1:4  and   1:8,   mercury  leaching concentration of all the solidified form were lower than 0.25 mg/L.
(4)  And   the   milled  solid   samples  were   characterized  by   ICP-OES,  XRD spectrum and XPS  spectrum in order to determine the  final binding form of mercury.The XRD and  XPS results showed that  mercuric sulfide was formed  from sulfur and mercury chloride in  the ball milling  process, which was different  from the formation of  HgS  deriving  from sulfur  and  mercury.  And  activated  carbon  and  free radical played important role in the formation of HgS during the milling process .
    The results of this study indicated that mechanochemical stabilization/solidification of waste mercuric chloride catalyst generated  from calcium carbide-based PVC industry  had the potential to be  used at industrial scale. Based  on this   research,   the   constriction   of   demonstration   project   for   mechanochemical stabilization/solidification  of  should  be  considered  seriously,  aiming  at   providing engineering practical experience for the  safe and harmless disposal of waste  mercuric chloride catalyst generated massively from PVC industry.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/34365
Appears in Collections:固体废弃物处理与资源化实验室_学位论文

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Recommended Citation:
任亚峰. 基于机械化学法的PVC行业废汞触媒稳定化固化技术及应用研究[D]. 北京. 中国科学院研究生院. 2015.
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