铅锌多金属尾矿砂的淋洗处理技术研究

发布时间：2018-07-18 14:00

【摘要】：我国是一个矿业生产大国,矿产的开采利用在极大地促进经济发展的同时也带来很大的环境污染问题,这些问题主要是由于尾矿渣中含有大量的重金属污染物造成的。尾矿是矿业冶炼的废弃物之一,它的堆放不仅占用土地资源,还会对周围环境造成极大污染破坏,导致矿区及周边土壤质量下降,破坏生态系统的正常功能,危害人类健康。本论文以陕西省商洛市某铅锌矿多金属尾砂为研究对象,对尾砂的化学淋洗修复技术进行研究,主要包含以下两个方面的内容：一是重金属去除率随淋洗条件改变的变化规律及不同淋洗剂淋洗的最适条件；二是复合淋洗剂对尾砂重金属的淋洗效率研究。本论文选用多种淋洗剂采用震荡淋洗法研究了单一淋洗剂对重金属的淋洗效果；探明了几种淋洗效果较好的淋洗剂的最佳淋洗条件；探究了复合淋洗剂对重金属的淋洗效率,得出各复合淋洗剂的最佳浓度配比,旨在为各淋洗剂去除多金属尾砂的实际处理提供参考和借鉴。实验结果表明,实验所取铅锌尾砂重金属含量很高,总Pb、总Zn、和总Cd、总As的含量均超过土壤环境质量标准,研究的As、Zn、Co、Mo、Pb、 Cd、Cu这7种重金属均超过采样点当地的土壤重金属含量背景值。通过BCR形态分析法可知,Co、Pb的生物可利用性高,易迁移转化；As和Zn的残渣态含量很高,活性弱,较为稳定。不同淋洗剂对重金属的去除效率差距较大,在六种淋洗剂中,盐酸、硝酸和EDTA处理效果最好,其对重金属的淋洗量都明显高于其他淋洗剂,其次是FeCl3,(NH4SO4)2溶液和CaCl2溶液对所研究的几种重金属的去除率均较低。对于本次淋洗实验,淋洗剂浓度对各金属淋洗效率的影响最大,其次是固液比和时间,相对来说淋洗次数的影响较小。实验对HCl、HNO3、EDTA、FeCl3几种淋洗效果较好单一淋洗剂进行条件优化,综合成本,淋洗剂用量,实际操作量等因素,得出浓度为0.05tmol·L-1的HCl,在固液比为1：10,淋洗时间为6小时,对尾砂进行一次淋洗可得到较好的淋洗率；0.1mol·L-1的HNO3,在固液比为1：10,淋洗时间为12h,对尾砂进行一次淋洗可得到较好的淋洗率；0.05mol·L-1的EDTA,在固液比1：10,淋洗时间为18h,对尾砂进行一次淋洗可得到较好的淋洗率；1.0mol·L-1为FeCl3,在固液比1：15,淋洗时间为12h,对尾砂进行两次淋洗可得到较好的淋洗率与单一淋洗剂相比,复合淋洗淋洗剂的淋洗效率均有提升。较高浓度EDTA、FeCl3与HCl、HNO3复配后,其协同作用减弱甚至呈现拮抗作用,表明在复合淋洗剂淋洗时并不是淋洗剂浓度越大就会又越好的淋洗效果。综合各复合淋洗剂对各重金属的去除效率,HNO3-FeCl3对各重金属的处理效果最好。总体来看,复合淋洗剂对尾砂中重金属有较好的去除效果。尾砂相比土壤来说,重金属含量更多,形态更为稳定,对于理化性质改变的条件不太苛刻,因而用淋洗法修复尾砂重金属有较好的前景。
[Abstract]:China is a big mining country, the exploitation and utilization of mineral resources not only greatly promote the economic development, but also bring a lot of environmental pollution problems. These problems are mainly caused by a large number of heavy metal pollutants in the tailings. Tailings is one of the wastes of mining smelting. Its stacking not only occupies the land resources, but also pollutes the surrounding environment, which results in the deterioration of soil quality in the mining area and surrounding areas, the destruction of the normal function of the ecosystem and the harm to human health. In this paper, the chemical leaching and remediation technology of the tailings from a lead and zinc mine in Shangluo City, Shaanxi Province, was studied. It mainly includes the following two aspects: first, the change of heavy metal removal rate with leaching conditions and the optimum conditions of different eluents; second, the study on the leaching efficiency of heavy metals in tailings. In this paper, the effects of single eluent on heavy metals were studied by means of shock elution, the optimum conditions of several eluents with better elution effect were found out, and the elution efficiency of complex eluents for heavy metals was investigated. The optimum concentration ratio of each compound eluant is obtained to provide reference for the practical treatment of polymetallic tailings. The results showed that the content of heavy metals in lead-zinc tailings was very high, and the contents of total Pb, Zn, CD and as exceeded the standard of soil environmental quality. The contents of seven heavy metals, such as Pb and CD, Cu in the soil, exceeded the background values of the soil heavy metals in the sampling sites. By BCR speciation analysis, it was found that the bioavailability of Cochon Pb was high, the residual state content of as and Zn was very high, the activity was weak, and the activity was relatively stable. Among the six eluents, hydrochloric acid, nitric acid and EDTA had the best effect, and the amount of heavy metals eluted was significantly higher than that of other eluents. The removal efficiency of several heavy metals in FeCl _ 3, (NH _ 4SO _ 4) _ 2 and CaCl _ 2 solutions was lower. For this elution experiment, the concentration of eluant has the greatest influence on the leaching efficiency of metals, followed by the ratio of solid to liquid and the time, and the relative number of times of leaching has little effect. By optimizing the conditions, synthesizing the cost, the amount of the eluent and the actual operating quantity of several kinds of eluent such as HCl HNO3 / EDTAFeCl3, the results show that the concentration of HCl-1 is 1: 10 and the elution time is 6 hours at the solid-liquid ratio of 1: 10, and the eluent time is 6 hours at the ratio of solid to liquid. A better leaching rate of HNO _ 3 of 0.1 mol L ~ (-1) can be obtained by one elution of tailings, and the better leaching rate can be obtained when the solid-liquid ratio is 1: 10 and the elution time is 12 h. When the ratio of solid to liquid is 1: 10 and the elution time is 18 h, the better elution rate can be obtained by once eluting the tailings. 1.0mol L-1 is FeCl _ 3, the ratio of solid to liquid is 1: 15, and the elution time is 12 h. The better elution rate can be obtained by twice eluting the tailings, and the elution efficiency of the compound eluant is higher than that of the single eluant. The synergistic effect of high concentration EDTA-FeCl _ 3 and HClTa-HNO _ 3 was weakened or even antagonized, which indicated that the higher the concentration of eluent was, the better the elution effect was. The removal efficiency of each heavy metal by synthesizing the compound eluent is the best. HNO _ 3-FeCl _ 3 has the best effect on the treatment of each heavy metal. In general, the combined eluent has a better removal effect on heavy metals in tailings. Compared with soil, tailings contain more heavy metals and form more stable, which is not too harsh for the change of physical and chemical properties, so it has a good prospect to remediate heavy metals in tailings by leaching.
【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】：X75

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