硫铁矿冶炼废渣的Pb和Cd释放迁移规律研究

发布时间：2018-07-29 14:59

【摘要】：本论文以重庆市某磺硫厂的炼硫废渣为研究对象,对废渣的表征特性和电动去除技术开展专门研究。具体内容有:对废渣的特性进行表征,研究废渣中Pb和Cd的形态结构和在电场作用下的迁移影响规律;研究在三维电极条件下,重金属的迁移和去除能效变化;分析电动去除重金属的机理和迁移传质规律。得到了以下结论:废渣样品中含有多种以氧化物、硅酸盐相存在的重金属元素;废渣样品呈现弱酸性,电动去除实验时酸性条件易于重金属的迁出。浸出毒性实验结果表明,释放的重金属只是较少的部分,重金属的释放应是一个长期的积累过程。形态分析结果表明,废渣中Cd比Pb的可提取态含量百分比更大,Cd更容易释放进入环境中。电动去除实验研究表明,随着电压梯度的升高和pH值的减小,废渣中Pb和Cd的去除率逐步增大,且在相同条件下,Cd的去除率比Pb小。pH值的变化主要影响Pb的酸可提取态,电压梯度的变化主要影响Pb的可还原态;废渣中Pb的酸可提取态和可还原态是影响Pb电动去除效率的两个主要因素。电压梯度的变化和pH值的变化主要影响Cd的可氧化态,对酸可提取态、可还原态的影响不大;废渣中Cd的可氧化态是影响Cd电动去除效率的主要因素。添加三维电极后:对样品区电压降和pH值的影响不大,电流的变化趋势也相同,但系统中电流达到最大值的时间缩短约24 h,系统电流变大;Pb和Cd的去除率有显著提升,其中Pb的最大去除率提高了31.88%,Cd的最大去除率提高了24.5%;废渣中重金属的释放量增加,增强了部分废渣中重金属元素由残渣态向非残渣态转移,降低了废渣中重金属元素的环境活性;处理的单位质量废渣的能耗有明显降低。本论文取得了以下创新性研究成果:(1)首次将形态分析方法用于硫铁矿冶炼废渣中重金属电动去除过程的研究,提出Pb和Cd电动去除的效能与元素的形态结构密切相关,为硫铁矿冶炼废渣中Pb和Cd释放迁移的化学机制研究提供了支撑。(2)根据表征体内质量守恒,提出了电动去除过程中重金属污染物迁移的传质模型,从理论上论述了硫铁矿冶炼废渣中Pb和Cd释放迁移的电动效应和物理机制。(3)首次将三维电极技术应用于硫铁矿冶炼废渣中重金属的电动去除,较大程度上提升了重金属的去除效率并且同时降低了能耗。
[Abstract]:In this paper, the sulfur residue in a sulphur plant in Chongqing is studied. The characteristics of the waste residue and the electric removal technology are studied. The specific contents are as follows: the characterization of the waste residue, the study of the morphology and structure of Pb and Cd in the waste residue and the influence of the migration of the waste in the electric field; and the study of heavy metals under the condition of three-dimensional electrode. Migration and removal of energy efficiency changes; analysis of the mechanism of electrokinetic removal of heavy metals and the law of transfer mass transfer. The following conclusions are obtained: the waste residue contains a variety of heavy metal elements in the presence of oxide and silicate; the waste residue samples are weak acid, and the acid strip is easy to move out of heavy metals in the experiment of electrokinetic removal. The result of the leaching toxicity test result table The release of heavy metals is only a few parts, and the release of heavy metals should be a long-term accumulation process. The results of morphological analysis show that the percentage of Cd in the waste residue is greater than that of Pb, and Cd is easier to release into the environment. The experimental study of electrokinetic removal shows that the Pb and Cd in the waste residue with the increase of voltage gradient and the decrease of the pH value. The removal rate of Cd is gradually increasing, and under the same conditions, the change of the removal rate of Cd is mainly influenced by the small.PH value of the Pb. The change of the voltage gradient mainly affects the reducible state of the Pb. The acid extractable and reducible states of Pb in the waste residue are the two main factors affecting the efficiency of Pb removal. The change of voltage gradient and the change of pH value are the main factors. The oxidizing state mainly affects the oxidizable state of Cd, which has little effect on the extractable state of acid and reducible state. The oxidizable state of Cd in the waste residue is the main factor affecting the efficiency of Cd removal. After adding the three-dimensional electrode, the influence of the voltage drop and the pH value of the sample area is not significant, and the trend of the current is the same, but the time of the maximum current in the system is shortened. About 24 h, the system current becomes larger, the removal rate of Pb and Cd is improved significantly, the maximum removal rate of Pb is increased by 31.88%, the maximum removal rate of Cd is increased by 24.5%, the release of heavy metals in the waste residue increases, and the heavy metal elements in the waste residue are transferred from residue state to non residue state, and the environmental activity of heavy metals in the waste residue is reduced. The energy consumption of unit mass waste is obviously reduced. The following innovative research results are obtained in this paper: (1) the study on the electrokinetic removal of heavy metals in the pyrite smelting waste residue is first studied by the morphological analysis method for the first time. It is suggested that the efficiency of Pb and Cd removal is closely related to the morphological structure of the elements, which is the Pb and C in the pyrite smelting waste residue. The research on the chemical mechanism of D release migration provides support. (2) according to the characterization of the mass conservation in the body, a mass transfer model for the migration of heavy metal pollutants in the process of electrokinetic removal is proposed. The electric effect and the physical mechanism of the release and migration of Pb and Cd in the pyrite smelting waste residue are theoretically discussed. (3) the application of three-dimensional electrode technology to pyrite for the first time The electric removal of heavy metals in smelting slag greatly improves the removal efficiency of heavy metals and reduces energy consumption.
【学位授予单位】：重庆大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：X753

【相似文献】