【作者】 王庆伟；

【导师】 柴立元；

【作者基本信息】 中南大学 ， 冶金环境工程， 2011， 博士

【摘要】 我国是世界铅锌第一生产大国,2009年铅、锌产量分别达370.79万吨和435.67万吨。铅锌冶炼过程产生的大量SO2烟气主要用于制硫酸,烟气中还含有汞等重金属烟尘,烟气制酸前在洗涤除尘过程中产生大量高浓度酸性重金属废水(简称污酸)。污酸废水酸度高,其中含有多种重金属离子,且重金属离子浓度高,形态复杂,毒性大。传统的硫化处理方法难以实现稳定达标。污酸若得不到有效的处理而排放入环境,将会给水体带来严重的污染。本研究以株洲冶炼集团铅锌冶炼过程烟气洗涤产生的污酸为研究对象,其性质非常复杂。污酸中硫酸的含量在2-4%之间,还溶解了高浓度的SO2酸性气体,主要含有汞、铜、铅、锌、镉、砷等重金属离子,以及高浓度的氟、氯及硫酸根离子。针对目前采用硫化法处理含汞污酸难以稳定达标的现状,研究了污酸的性质,提出了污酸生物制剂法处理新工艺,主要研究成果如下：通过研究污酸的性质及其中汞的赋存形态,确定了污酸中汞主要有三种赋存形态：颗粒态、胶体态和离子态；通过研究硫化法处理污酸的热力学,剖析了硫化法处理污酸重金属不能稳定达标的原因,为解决胶体汞去除的难题奠定了理论基础。采用电毛细曲线法研究了污酸中汞胶体的结构,建立了污酸中汞胶体结构模型,结果表明原子态汞进入污酸溶液将优先超载吸附HgCl42-形成三电层结构,并对其形成胶体键能进行了分析,发现原子汞表面和HgCl42-之间产生的键能较弱。根据Gouy-Chapman-Stern (GCS)模型对汞胶体的zeta电位进行了推算,并考察了溶液中的金属阳离子对胶体汞稳定性的影响,提出了污酸中胶体汞的破坏方法。开发了“生物制剂配合—水解”处理污酸新工艺,研制了处理含汞污酸的生物制剂,并优选了一种高分子阳离子化合物——脱汞剂,通过生物制剂和脱汞剂的协同作用同时深度脱除污酸中的汞及其他重金属离子。生物制剂基于其中含有的多种功能基团脱除污酸中离子态汞和其他重金属离子,实现出水高效净化。脱汞剂主要通过压缩双电层破坏胶体汞的结构,以网捕架桥的作用使胶体汞发生絮凝沉淀。通过单因素和正交试验确定了生物制剂法脱除污酸中汞及其他重金属的最优条件：生物制剂/Hg=16,脱汞剂投加量16mg/L,配合反应时间30min,水解pH值10.0,水解时间30min,处理后出水中各重金属离子浓度均达到《污水综合排放标准》(GB 8978-1996)。为了将实验室的研究成果转化为生产力,使化学反应适应实际工业生产,在株冶污酸工段现场进行了污酸(15-30m3/h)生物制剂连续化处理的中间试验。研究开发了多级溢流反应设备,基于计算机模拟优化设计了管道反应器,实现了生物制剂、脱汞剂与污酸中重金属的高效混合反应,并优化工艺参数,确定了工业生产过程中各药剂的投加量和生产参数：生物制剂/汞=40,脱汞剂的投加量为20g/m3,水解pH值10-11。新工艺在株冶原硫化设施上进行了试运行,通过湖南省环境监测站连续48小时的跟踪监测分析,结果表明处理后出水中各重金属离子浓度均达到《污水综合排放标准》(GB 8978-1996)。基于污酸中不同形态汞的特征,提出增加均化工序以净化颗粒态汞的新思路。在株冶原硫化处理设施上进行工业试验,为污酸生物制剂处理工艺改造提供设计参数,同时为污酸渣的综合利用提供依据。工业试验结果表明,生物制剂法通过均化、配合、水解三个过程,实现对污酸中的汞以及其他重金属同时深度处理,回收的均化渣和配合渣中汞的质量分数分别为28.31%和45.08%,均可以作为冶炼原料回收其中的重金属。水解渣中重金属含量低,便于安全处置。在工业试验的基础上,株冶集团根据生物制剂法处理流程对污酸处理系统进行了全面的升级改造。建成了100m3/h的工程示范,该技术列于2009年度国家先进污染防治示范技术名录,可为国内同类废水处理提供可行技术。更多还原

【Abstract】 China is the world’s largest producer of lead and zinc. The amount of lead and zinc produced in 2009 reached 3.71 and 4.36 million tons, respectively. Lead and zinc smelting process generates a great deal of sulfur dioxide gas, which is mainly used for the production of sulfuric acid. This smelting gas also contains mercury and other heavy metals. High concentration of acidic wastewater containing heavy metals (shorten as acidic wastewater) was generated in the washing process before the production of sulfuric acid. This acidic wastewater has high acidity and contains various toxic heavy metal ions of high concentration and in complex form. The traditional sulfide approach is difficult to achieve stable discharge standard. If acidic wastewater discharged into the environment without effective treatment, it will bring serious pollution to the water system.This study was aiming at acidic wastewater generated from the gas washing process of lead and zinc smelting in Zhuzhou Smelter, its character was very complex. The content of sulfuric acid in acidic wastewater was 2-4%. It also dissolved high concentration of acidic SO2 gas, which mainly contains heavy metals such as Hg, Cu, Pb, Zn, Cd, As and high concentration of F, Cl, sulfate ions. Treatment of acidic wastewater containing mercury by sulfide method is difficult to stably meet the discharge standards, thus the properties of acidic wastewater was studied and the novel technique was invented to treat acidic wastewater by biologics. The main results are as follows:Based on the properties of acidic wastewater, it can be confirmed that the speciation of mercury in acidic wastewater was complex, which mainly includes three kinds of forms, i.e., granule state, colloid state and ion state. Moreover, thermodynamic studies about treatment of acidic wastewater using sulfide method revealed the reasons why the acidic wastewater treated by sulfide can not meet the emission standards stably. The theoretical foundation was established to solve the difficult problem of removal colloidal mercury from acidic wastewater.The structure of colloidal mercury was studied by electrocapillary curve and the model of colloidal mercury in acidic wastewater was established. When the atomic mercury was entered into the acidic wastewater, it preferentially adsorbed HgCl42- to form three-electron-layer structure. Moreover, its colloidal bond energy was analyzed. The result indicated that the bond energy between the surface of mercury and HgCl42- was weak. The zeta potential of colloidal mercury was calculated according to Gouy-Chapman-Stern model. In addition, effect of metal cations in solution and cationic compounds of organic polymer on the stability of colloidal mercury were also investigated. Thus, a new method for destroying the structure of colloidal mercury in acidic wastewater was developed.Novel technology of "biologics complex-hydrolysis" for treatment of acidic wastewater containing mercury was invented. Water treatment reagent—biologics and a kind of cationic compounds of organic polymer—demercuration were developed to deeply remove mercury and other heavy metal ions from acidic wastewater. Biologics containing various functional groups can be used to remove ionic mercury and other heavy metal ions by forming complexes. Demercuration was used to destroy the structure of colloidal mercury by compressing double-layer. Demercuration was also used to make colloidal mercury sedimentation in flocculation via fishing and bridging effect. Single-factor experiment combined with orthogonal experiment were carried out to determine the optimal conditions for removing mercury and other heavy metals in acidic wastewater using biologics. Under the following optimal conditions:biologics to mercury ratio was 16, the dose of demercuration was 16mg/L, complexing reaction time was 30min, hydrolysis pH was 10.0 and hydrolysis time was 30min, heavy metals in treated water reached Integrated wastewater discharge standard (GB 8978-1996).In order to transfer the laboratory research into productive forces and make the chemical reaction suitable for industrial production, the pilot test (15-30m3/h) was carried out continuously in acidic wastewater section of Zhuzhou Smelter. A multi-level spill response equipment was invented; moreover, the pipe reactor was designed with the help of computer simulation and optimization. The efficient reaction of biologics and demercuration agent with acidic wastewater was realized and the optimal parameters for industrial production were determined as follows: biologics to mercury ratio was 40, the dose of demercuration was 20 g/m3, hydrolysis pH was 10-11. Trial operation of this new technology was carried out in Zhuzhou Smelter based on the original facilities for sulfide method. The results was continuously tracked and monitored for 48 hours by Hunan Environmental Monitoring Station, which indicated that heavy metals in treated water meet Integrated wastewater discharge standard (GB 8978-1996).Based on the characteristics of different species of mercury in acidic wastewater, the new idea of increasing the homogenization process to purify particulate mercury was proposed. In order to offer the design parameters for process modification of acidic wastewater treatment by biologics and provide evidence for the comprehensive utilization of the slag generated from the acidic wastewater treatment, industrial experiment was carried out. The results indicated that simultaneous and deep removal of mercury and heavy metals from acidic wastewater was realized via homogenization, complex and hydrolysis processes of biologics method. Moreover, the content of mercury in the recovered homogenization slag and in the recovered complex slag was 28.31% and 45.08%, respectively. Thus, the recovered homogenization slag and the recovered complex slag can be used as raw materials for smelting to recover the heavy metals. However, the low content of heavy metals in the recovered hydrolysis slag led to its safe disposal.On the basis of the industrial experiment, the system of acidic wastewater treatment in Zhuzhou Smelter was comprehensively upgraded according to the flow of biologics method. The demonstration project of 100m3/h was established. This technology was listed in the advanced pollution control technology of 2009, which provides an available technology for treating domestic acidic wastewater containing mercury.更多还原