金矿石尾矿中重金属的淋洗处理及条件优化研究

发布时间：2018-03-08 18:24

本文选题：重金属　切入点：尾矿　出处：《陕西师范大学》2015年硕士论文　论文类型：学位论文

【摘要】：我国仍处于城镇化、工业化的快速发展时期,每天都在消耗大量的矿物资源,矿物资源经过选矿分选后会产生大量的尾矿,而尾矿的长期堆积造成的重大事故屡见不鲜,使我国经济和生态环境遭受了重大威胁。近年来,我国出台了大量与尾矿资源化、最小化和无害化相关的政策,特别是《尾矿的处置、管理及资源化示范工程》项目计划的出台,象征着我国已把尾矿的无害化处理和回收再利用作为新世纪的重中之重。目前,我国矿产资源开采产生的尾矿带来的环境污染问题主要表现为多重金属的复合污染。国内外针对去除土壤中污染重金属已做了大量研究,而关于对尾矿中的污染重金属的无害化处理研究甚少,在众多的治理措施中化学淋洗法因其操作简单、速率快、效率高和成本适中等优点而被广大学者所青睐。本研究选用硝酸、盐酸、乙二胺四乙酸和氯化铁四种淋洗剂,选取单一淋洗剂淋洗和两种淋洗剂复合淋洗的方法,以陕西省商洛市某选矿厂尾矿库采集的黄金尾矿为研究对象,寻求单一淋洗剂的最优淋洗条件和最佳单一淋洗剂,以及最佳复合淋洗剂和复合淋洗剂的最佳浓度、液固比、淋洗时间等淋洗条件。采用HF+HClO4+HNO3消解分析测定尾矿中重金属的含量,通过BCR四步连续提取法分析了重金属的乙酸可提取态、可还原态、可氧化态和残渣态四种形态的具体含量,寻求最佳的淋洗剂从而能够在实践中高效地对尾矿进行无害化处理。结果表明：(1)金矿石尾矿中重金属Pb、Co、Ni、Sr、Cu、As的含量分别为70.00、47.25、40.9、315.25、41.65和1930.25 mg/kg,其中,As的含量是陕西省背景值的173倍。尾矿中重金属Pb、Ni、Cu、As主要是以残渣态的形式存在,其含量分别为46.35%、47.07%、53.43%、73.43%；Co以可还原态为主,含量为32.09%,其次是残渣态含量为31.34%，，其乙酸提取态和可氧化态含量分别为21.31%和15.26%；Sr的残渣态含量较低,仅为5.47%,Sr主要是以乙酸提取态和可还原态存在,分别占到57.54%和36.13%。形态分析法表明,Co、Sr的残渣态含量低,生物可利用性高,迁移转化能力强；Pb、Ni、Cu的残渣态含量与有效态含量相当,生物可利用性较高,迁移转化能力较强；As的残渣态含量很高,生物活性弱,较为稳定。(2)四种单一淋洗剂对尾矿的最优浓度、最佳固液比、最佳淋洗时间、淋洗次数如下：HN03,1mol/L,15:1,16h,1次；HNO3在最佳淋洗条件下对重金属As、Cu、Ni、 Pb、Co、Sr的淋洗率分别为27.77%、39.80%、24.57%、26.87%、20.89%、65.80%。HCl,2mol/L,15:1,6h,1次；HCl在最佳淋洗条件下对重金属As、Cu, Ni, Pb, Co, Sr的淋洗率分别为44.23%、45.29%、28.57%、31.54%、18.48%、56.67%。EDTA, 0.1mol/L,10:1,6h,2次；EDTA在最佳淋洗条件下对重金属As、Cu、Ni、Pb、Co、Sr的淋洗率分别为4.31%、22.05%、9.22%、14.44%、23.61%、42.62%。FeCl3,0.5mol/L,10:1,12h, FeCl3在最佳淋洗条件下对重金属As、Cu、Ni、Pb、Co、Sr的淋洗率分别为40.83%、68.69%、13.64%、63.97%、51.24%、69.36%。(3)综合分析五种复合淋洗剂HCl-EDTA、HNO3-EDTA、HCl-FeCl3、 HNO3-FeCl3、EDTA-FeCl3对尾矿中六种重金属As、Cu、Ni、Pb、Co、Sr的淋洗效果,得出五种复合淋洗剂的淋洗效率都远比单一淋洗剂盐酸、硝酸、氯化铁和乙二胺四乙酸的淋洗率要高,复合淋洗剂对重金属的淋洗率随单一淋洗剂盐酸、硝酸、氯化铁和乙二胺四乙酸浓度的升高而增高。比较五种复合淋洗剂对重金属的淋洗效果可知,复合淋洗剂HCl-FeCl3对尾矿中Cu的淋洗效率优于其他复合淋洗剂；复合淋洗剂HCl-FeCl3和HNO3-FeCl3对As的淋洗效率较为接近且优于其他复合淋洗剂；复合淋洗剂HCl-FeCl3和EDTA-FeCl3对Ni的淋洗效率较为接近且优于其他复合淋洗剂；复合淋洗剂HCl-FeCl3和HNO3-FeCl3对Sr的淋洗效率较为接近且优于其他复合淋洗剂；复合淋洗剂HCl-FeCl3、HNO3-FeCl3和EDTA-FeCl3对Co的淋洗效率较为接近且优于其他复合淋洗剂；复合淋洗剂HCl-FeCl3、 HNO3-FeCl3和EDTA-FeCl3对Pb的淋洗效率较为接近且优于其他复合淋洗剂。由上可知,复合淋洗剂都对As、Cu、Ni、Pb、Co、Sr有较高的淋洗率且远高于单一淋洗剂对重金属的淋洗率,其中,复合淋洗剂HCl-FeCl3对六种重金属As、Cu、 Ni、Pb、Co、Sr都有较高的淋洗效果且优于其他复合淋洗剂。复合淋洗剂HCl-FeCl3对尾矿进行淋洗的最佳浓度、最佳固液比、最佳淋洗时间、最佳淋洗次数如下：HC1,0.2mol/L, FeCl3, 1.0mol/L,6:1,6h,3次;HCl-FeCl3在最佳淋洗条件下对重金属As、Cu、Ni、Pb、Co、Sr的淋洗率分别为42.37%、76.18%、67.36%、78.91%、68.13%、79.04%。
[Abstract]:China is still in the period of rapid development of urbanization, industrialization, every day to consume a large amount of mineral resources, mineral resources after dressing after sorting will produce large amounts of tailings and tailings caused by long-term accumulation of major accidents It is often seen. to make the economy of our country, and the ecological environment suffered a major threat. In recent years, China promulgated a large number of tailings, minimization and harmless related policies, especially the "tailings disposal demonstration project management and resource project > plan, a symbol of our country has put the harmless treatment and recycling of tailings re-use as priority among priorities in the new century. At present, the problem of environmental pollution tailing exploitation of mineral resources in China have brought the main performance for the combined pollution of heavy metals. Many domestic and foreign to the removal of soil heavy metal pollution has done a lot of research, and on the heavy pollution of tailings in the metal Harmless little research in many control measures of chemical leaching method because of its simple operation, fast speed, high efficiency and low cost and is favored by the majority of scholars. This study used nitric acid, hydrochloric acid, EDTA and ferric chloride and four kinds of leaching agent, method of selecting a single with the eluent and two kinds of leaching agent leaching of the gold tailings in Shangluo city of Shaanxi Province, a concentrator tailings collected as the research object, the optimal elution conditions for single elutriant and single best eluant, and the optimal concentration of the best compound leaching agent and compound leaching agent, liquid-solid ratio, leaching leaching time. Using HF+HClO4+HNO3 digestion determination heavy metals in the tailings, through the BCR four step sequential extraction analysis of heavy metals in the acetic acid extractable, reducible, specific content of four kinds of oxidation state and residual state, In order to seek the best eluent in practice efficiently for tailings harmless treatment. The results showed that: (1) gold ore tailings, heavy metals of Pb, Co, Ni, Sr, Cu, As were 70.00,47.25,40.9315.25,41.65 and 1930.25 mg/kg, among them, the content of As is 173 times the background value in Shaanxi province. The heavy metals of Pb, Cu, As and Ni in the tailings, mainly exists in the form of residua, the contents were 46.35%, 47.07%, 53.43%, 73.43%; Co in reducible, content is 32.09%, followed by the residue content is 31.34%, the acetic acid extractable and oxidable contents were 21.31% and 15.26%; residual content of Sr is relatively low, only 5.47%, Sr is mainly in acid extractable and reducible fraction, respectively accounted for 57.54% and 36.13%. morphological analysis showed that the Co residue content of Sr is low, high bioavailability, migration and transformation ability; Pb, Ni, Cu. A content and available content, high bioavailability, migration and transformation ability; the residual content of As is very high, weak biological activity, relatively stable. (2) the optimal concentration of four kinds of single elutriant of tailings, the optimal solid-liquid ratio, optimum leaching time, leaching times are as follows: HN03,1mol/L, 15:1,16h HNO3, 1 times; in the best leaching of heavy metals As, Cu, Ni, Pb, Co, Sr leaching rate were 27.77%, 39.80%, 24.57%, 26.87%, 20.89%, 65.80%.HCl, 2mol/L, 15:1,6h, 1; HCl is As, the optimum leaching conditions heavily in Cu, Ni, Pb. Co Sr, the leaching rates were 44.23%, 45.29%, 28.57%, 31.54%, 18.48%, 56.67%.EDTA, 0.1mol/L, 10:1,6h, 2; EDTA in the best leaching of heavy metals As, Cu, Ni, Pb, Co, Sr leaching rate were 4.31%, 22.05%, 9.22%, 14.44%, 23.61%, 42.62%.FeCl3,0.5mol/L, 10:1,12h FeCl3, in the best leaching conditions The heavy metals of As, Cu, Ni, Pb, Co, Sr leaching rate were 40.83%, 68.69%, 13.64%, 63.97%, 51.24%, 69.36%. (3) comprehensive analysis of five kinds of compound leaching agent HCl-EDTA, HNO3-EDTA, HCl-FeCl3, HNO3-FeCl3, EDTA-FeCl3 of six kinds of heavy metals in the tailings of As, Cu, Ni, Pb, Co. The results of leaching of Sr, the leaching efficiency of five kinds of composite elutriant are far more than a single elutriant of hydrochloric acid, nitric acid, ferric chloride and EDTA leaching rate to be high, the composite leaching of heavy metal leaching rate with single drench lotion hydrochloric acid, nitric acid, ferric chloride and ethylene increased two amine four acetic acid concentration increased five. For the leaching effect of compound leaching agent for heavy metals, composite leaching leaching efficiency of HCl-FeCl3 is better than Cu in other tailings drench lotion; compound leaching agent HCl-FeCl3 and HNO3-FeCl3 leaching efficiency of As is closer and better than other drench drench lotion; HCl-FeCl3 and EDTA-FeCl3 leaching efficiency of lotion is close to Ni and better than the other composite eluant; compound leaching agent HCl-FeCl3 and HNO3-FeCl3 leaching efficiency of Sr is closer and better than the other composite eluant; compound leaching agent HCl-FeCl3, HNO3-FeCl3 and EDTA-FeCl3 leaching efficiency of Co is closer and better than the other composite eluant; compound leaching agent HCl-FeCl3 EDTA-FeCl3, HNO3-FeCl3 and Pb on leaching efficiency is closer and better than the other. It is the compound spray lotion, compound leaching agent of As, Cu, Ni, Pb, Co, Sr have higher leaching rate and much higher than that of single elutriant of heavy metal leaching rate, the eluent of six kinds of HCl-FeCl3 composite Cu, Ni, heavy metals As, Pb, Co, Sr have high leaching effect and better than the other composite eluant. The best concentration of compound leaching agent HCl-FeCl3 for leaching tailings, the optimal solid-liquid ratio, the most The best eluent time and the best eluent times are as follows: HC1,0.2mol/L, FeCl3, 1.0mol/L, 6:1,6h, 3 times; HCl-FeCl3 under the best leaching conditions, the leaching rates of heavy metals As, Cu, Ni, Pb, Co and Sr are 42.37%, 76.18%, 67.36%, 78.91%, 68.13%, respectively.

【学位授予单位】：陕西师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X753

【引证文献】