堆浸铀尾矿污染物释放机理研究

发布时间：2018-02-25 04:06

  本文关键词： 铀尾矿 淋浸 污染物 释放规律 铀浸出　出处：《南华大学》2015年硕士论文　论文类型：学位论文

【摘要】：铀尾矿是一种高容量、低放射性废物,常堆置于地表形成尾矿库,在地球化学作用下,其中的放射性核素及其他有毒物质将会释放出来,对库区周边水土造成污染,从而危害人类健康。了解铀尾矿中污染物的释放规律和控制释放的机制有助于制定对应的防范措施,以减轻铀尾矿对环境的不利影响。我国广东、江西等湿热地方铀矿众多,但是目前国内针对这些地方的铀尾矿放射性核素和有毒重金属元素的释放、迁移机理的研究较少,因此,对这些尾矿开展这方面的研究具有重要的实际意义。本文以广东韶关某铀尾矿库的尾矿为研究对象,分析其物理化学性质,然后对铀尾矿进行模拟自然条件下的动态淋浸实验,研究铀尾矿中铀及其他污染物的释放规律,并对各金属元素的释放进行动力学分析。论文的主要结论如下:1.该铀尾矿粒径较大,主要分布在0.1-10 mm之间;所含主要元素有硅、铁、铝、钾;主要矿物有石英、微斜长石、高岭石、石膏、斜绿泥石;尾矿中铀、铅、锌、镉以残渣态为主,铁、锰主要以铁锰氧化物/氢氧化物结合态为主.2.铀尾矿动态淋浸的淋滤液p H值呈上升的趋势,其变化范围为3.3-4.84;尾矿中铀、铁、锰、锌、镉、铅和硫酸根离子等污染物在淋浸初期释放较快,后期逐渐变慢,淋浸液中铀浓度远大于铀尾矿库铀的排放限值50 ug/L,其他污染物的浓度也超过地下水Ⅲ类水质标准的限值。3.几种金属的累积浸出量大小为铀锰铁锌镉铅,取决于各元素总量及元素在尾矿中存在的形态。4.浸出液中铀浓度最高达286.66 mg/L,经过2个月淋浸实验,铀累积释放量达158.06 mg/Kg,具有回收价值。5.铁、锰的释放可用准二级动力学方程很好的拟合;铅、锌、镉的释放用抛物线扩散方程拟合较好;铀的释放具有阶段性,淋浸0-24 h,铀的释放符合一级动力学,24 h-1464h,铀的释放符合二级动力学方程。
[Abstract]:Uranium tailings are high capacity, low radioactive wastes, often deposited on the surface to form tailings reservoirs. Under geochemical action, radionuclides and other toxic substances will be released, resulting in pollution of water and soil around the reservoir area. Therefore, it is harmful to human health. Understanding the release law of pollutants in uranium tailings and the mechanism of controlling the release will help to formulate corresponding preventive measures to mitigate the adverse effects of uranium tailings on the environment. There are many uranium deposits in humid and hot areas such as Guangdong and Jiangxi in China. However, at present, there are few studies on the migration mechanism of radionuclides and toxic heavy metal elements from uranium tailings in China. It is of great practical significance to study these tailings. In this paper, the physical and chemical properties of the tailings of a uranium tailings reservoir in Shaoguan, Guangdong Province, are analyzed, and the dynamic leaching experiments of uranium tailings under simulated natural conditions are carried out. The release regularity of uranium and other pollutants in uranium tailings is studied, and the release kinetics of each metal element is analyzed. The main conclusions of this paper are as follows: 1. The size of uranium tailings is large, mainly distributed in the range of 0.1-10 mm. Aluminum, potassium; main minerals are quartz, microplagioclase, kaolinite, gypsum, clinopyrite; uranium, lead, zinc, cadmium in tailings are mainly residual, iron, Mn is mainly iron-manganese oxide / hydroxide bound state .2.The pH value of leaching filtrate in dynamic leaching of uranium tailings shows an upward trend, and its variation range is 3.3-4.84, uranium, iron, manganese, zinc, cadmium in tailings, uranium, manganese, zinc, cadmium, uranium, manganese, zinc, cadmium, uranium, manganese, zinc, cadmium, uranium, manganese, zinc and cadmium in tailings. Pollutants such as lead and sulfate ions were released rapidly in the early stage of leaching, and gradually slowed down in the later period. The concentration of uranium in leaching solution is much larger than the limit value of uranium discharge from uranium tailings reservoir by 50 ugL, and the concentration of other pollutants exceeds the limit value of groundwater class 鈪，

本文编号：1532921