Experimental and numerical study on heavy metal contaminant migration and retention behavior of engineered barrier in tailings pond
Experimental and numerical study on heavy metal contaminant migration and retention behavior of engineered barrier in tailings pond
复制标题
尾矿库工程屏障重金属污染物迁移与滞留行为实验与数值研究
DOI：
10.1016/j.envpol.2019.06.072
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发表时间：
2019-09-01
影响因子：
8.9
通讯作者：
Ye, Wei-min
中科院分区：
文献类型：
--
作者：
He, Yong;Li, Bing-bing;Ye, Wei-min
重金属污染是一个严重的全球性环境问题，特别是在矿山和尾矿库。在室内试验和现场试验的基础上，采用数值模拟方法分析了尾矿库中重金属污染物的迁移规律以及压实膨润土工程屏障系统对重金属污染物的截留行为。结果表明，压实膨润土的导水率低于室内试验尾矿的导水率。尾矿砂的导水率随着干密度的增加而减小，随着化学溶液浓度的增加而增大，这可能是由于尾矿中含有大量的细粒土，根据粒度分布测试。工程地质调查尾矿导水率在2.0 × 10 ~（-6）~ 9.0 × 10 ~（-5）m/s之间，导水率大小顺序为：尾矿粗砂>尾矿粉砂>尾矿中砂>尾矿细粉砂。渗流场的数值模拟能够较好地描述尾矿坝的实际工作情况。在地下水渗流的作用下，尾矿库中重金属污染物的迁移范围在5 a内最大可达45 m。0.2m工程屏障对重金属污染物的15年和30年的截留率分别为45.4%和57.2%。此外，当工程屏障厚度增加到0.5 m时，截留效率将超过87%。模型验证结果表明，计算结果与实测结果吻合较好。研究结果可为矿山和尾矿库环境污染的防治提供有效的思路。(C)2019爱思唯尔有限公司版权所有。
Heavy metal pollution is a serious environmental problem globally, particularly in mines and tailings ponds. In this study, based on laboratory and field tests, the migration of heavy metal contaminants in a tailings pond and the retention behavior of a compacted bentonite engineered barrier system on the heavy metal contaminants were analyzed by a numerical simulation. The results demonstrate that the hydraulic conductivity of compacted bentonite is lower than that of the tailings from the laboratory tests. The hydraulic conductivity of the tailings sand decreased with an increase in the dry density and increased with an increase in the concentration of the chemical solution, which could be attributed to the large amounts of fine-grained soil contained in the tailings, according to the grain size distribution test. The hydraulic conductivity of the tailings from the engineering geological survey was between 2.0 x 10(-6) and 9.0 x 10(-5) m/s, and followed the order: tail coarse sand > tail silty sand > tail medium sand > tail fine silt. The numerical simulation of the seepage could satisfactorily describe the actual working condition of the tailings dam. With the groundwater seepage, the migration range of the heavy metal contaminant in the researched tailings pond reached a maximum of 45 m for 5 years. The retention efficiencies of the 0.2 m engineered barrier against the heavy metal contaminant for 15 and 30 years were 45.4% and 57.2%, respectively. Moreover, the retention efficiency would exceed 87% when the engineered barrier thickness is increased to 0.5 m. The results of model validation show that the calculated results are in good agreement with the measured ones. These findings can provide effective ideas for the prevention and control of environmental pollution in mines and tailings ponds. (C) 2019 Elsevier Ltd. All rights reserved.