• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Comportement hydrogeologique d'une couverture monocouche sur des residus miniers sulfureux: Essais en colonne et simulations numeriques.
【24h】

Comportement hydrogeologique d'une couverture monocouche sur des residus miniers sulfureux: Essais en colonne et simulations numeriques.

机译：含硫采矿残渣上单层覆盖物的水文地质行为：柱试验和数值模拟。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

One of the main environmental problems facing the mining industry results from the surface storage of reactive tailings. Such tailings result from the milling process, where the extracted ore is crushed and treated to concentrate selected minerals and metals. When in contact with water and air, sulphide minerals contained in the tailings can oxidise and generate acid mine drainage (AMD). These acidic waters have a low pH ( 3) and may contain high concentrations in dissolved sulphates and metals. To meet environmental regulations, mining companies need to prevent or at least reduce AMD production. The oxidation reactions can be controlled by excluding one of the constitutive components of the reactions, i.e. water or oxygen. The main methods used under humid climates to prevent AMD formation are oxygen barrier such as water covers and covers with capillary barrier effects (CCBE). An alternative method is the use of the elevated water table technique applied in conjunction with a monolayer cover. To date however, relatively little work has been done on this technique for practical situations.;The characterisation of the tailings and cover properties was done in the laboratory to determine their grain size distribution, relative density, optimum Proctor unit weight, saturated hydraulic conductivity, water retention curve, oxygen diffusion and reaction coefficients, and mineralogical composition. The results indicate that the values obtained for the saturated hydraulic conductivity (ksat), water retention curve (WRC), and diffusion coefficient (De) are comparable to estimated values calculated from predictive models.;A field work campaign was also conducted to assess some aspects of the in situ hydrogeological behaviour in terms of water table position and water content, and to collect additional samples of the cover material (till) to evaluate its heterogeneity.;Four columns were built in the laboratory with the characterised materials, to create physical models of the tailings-cover system. Two tall columns made of tailings (1.7 m) covered with a layer of till (30 cm) are used to investigate the hydrogeological behaviour of the system. Two small columns made of a single layer of tailings (left uncovered) are mainly used to characterize the geochemical behaviour of exposed tailings. The columns are instrumented with probes to monitor the water content and the pressure in the tailings and cover. The results obtained after the first five cycles of wetting-drainage, are presented in the Thesis; the experiments are ongoing, and the remainder of the results will be presented elsewhere.;This project aims at studying the behaviour of a monolayer cover implemented with an elevated water table on reactive tailings. The investigation includes the evaluation of the effect of various parameters on the capacity of the cover to act as an oxygen barrier or as an evaporation barrier, depending on the position of the water table. The study is loosely based on some of the characteristics of the Selbaie mine site situated in the north-west of Quebec. This tailings impoundment has been partly reclaimed with a monolayer cover. The tailings and the cover material used in the laboratory column tests conducted here were collected from this site.;The experimental results are used to create a numerical model of the tailings-cover system with the commercial finite element code SEEP/W (GeoSlope Inc.), which serves to broaden the scope of the study to encompass some additional key parameters. More specifically, the numerical model is used to evaluate the effect of three factors on the behaviour of the system: the thickness of the cover, the hydrogeological properties of the cover material, and the water table depth in the tailings. Thirteen cases were simulated and are presented in the Thesis. The simulation results show that the thickness of the cover has no impact on the water content of the tailings and only a minor impact on that of the cover. The hydrogeological properties of the cover material have little impact on the response of the tailings below the cover (for the conditions considered in the model), but they have a significant effect on the cover behaviour. For instance, when the cover is made of a fine-grained material, it shows a significant capillary retention that keeps it highly saturated, even in the presence of a relatively deep water table. On the other hand, when made of a coarse-grained material, the cover tends to desaturate rapidly, even when the water table is shallow. The depth of the water table in the tailings has a minor impact on the behaviour of the monolayer cover (made of the reference material), but it has a strong influence on the water content of the tailings. In the presence of a deep water table, the tailings tend to desaturate naturally, whereas they can be kept highly saturated up to the surface with a shallow water table. Thus, the hydrogeolocial properties of the monolayer cover and the depth of the water table are two factors that have a major impact on the cover's ability to act as an evaporation barrier (for a very low water content) or as an oxygen barrier (for a high water content).;Based on these results, a few recommendations are formulated on the use of a monolayer cover implemented in conjunction with an elevated water table. When the water table is shallow in the impoundment, the tailings can be kept highly saturated. The monolayer cover should then serve to reduce evaporation, and must thus be made of a coarse-grained material that desaturates easily and rapidly. When the water table is deep, the tailings desaturate naturally and the cover should serve to block the oxygen flux towards the tailings. The cover should then be made of a fine-grained material layer, placed on a coarser material layer; the former can be kept highly saturated, even in the presence of a deep water table, due to the formation of a capillary break.
机译：采矿业面临的主要环境问题之一是反应性尾矿的表面储存。此类尾矿来自碾磨过程，在碾磨过程中将提取的矿石压碎并进行处理，以浓缩选定的矿物和金属。当与水和空气接触时，尾矿中所含的硫化物会氧化并产生酸性矿井排水（AMD）。这些酸性水的pH值低（<3），并且在溶解的硫酸盐和金属中可能含有高浓度的水。为了满足环境法规，采矿公司需要防止或至少减少AMD的产量。可以通过排除反应的组成成分之一，即水或氧气来控制氧化反应。在潮湿气候下用来防止AMD形成的主要方法是氧气阻隔层，例如水覆盖层和具有毛细屏障作用的覆盖层（CCBE）。一种替代方法是使用与单层覆盖物结合使用的升高的地下水位技术。然而，迄今为止，在实际情况下，在该技术上所做的工作相对较少。在实验室中对尾矿和覆盖层特性进行了表征，以确定它们的粒度分布，相对密度，最佳Proctor单位重量，饱和导水率，保水曲线，氧扩散和反应系数以及矿物组成。结果表明，所获得的饱和导水率（ksat），保水曲线（WRC）和扩散系数（De）的值与预测模型计算出的估计值可比。就地下水位和含水量而言的原位水文地质行为的各个方面，并收集覆盖材料（耕作）的其他样本以评估其非均质性;在实验室中用特征材料建造了四根色谱柱，以形成物理尾矿覆盖系统的模型。使用由尾矿（1.7 m）制成的两根高高的柱子覆盖一层耕作层（30 cm），来研究该系统的水文地质行为。由单层尾矿制成的两个小圆柱（未发现）主要用于表征裸露的尾矿的地球化学行为。色谱柱装有探针，以监测尾矿和盖层中的水含量和压力。在论文的前五个循环中得到了结果。实验正在进行中，其余结果将在其他地方进行介绍。该项目旨在研究在反应性尾矿上采用高水位的单层覆盖物的性能。该调查包括评估各种参数对盖子作为氧气屏障或蒸发屏障的能力的影响，具体取决于地下水位的位置。该研究大致基于魁北克西北部Selbaie矿场的某些特征。该尾矿库已被单层覆盖物部分回收。从此站点收集了此处进行的实验室柱测试中使用的尾矿和盖层材料;实验结果用于创建尾矿覆盖系统的数值模型，其商业代码为SEEP / W（GeoSlope Inc. ），以扩大研究范围，使其涵盖一些其他关键参数。更具体地说，该数值模型用于评估三个因素对系统性能的影响：覆盖层的厚度，覆盖层材料的水文地质特性以及尾矿中的地下水位深度。模拟了13个案例，并在论文中进行了介绍。仿真结果表明，覆盖层的厚度对尾矿含水量没有影响，而对覆盖层的含水量影响很小。覆盖层材料的水文地质特性对覆盖层以下的尾矿的响应影响很小（对于模型中考虑的条件），但是它们对覆盖层的行为具有重大影响。例如，当盖子由细颗粒材料制成时，即使在地下水位相对较深的情况下，它也显示出显着的毛细管滞留性，使其保持高度饱和。另一方面，当由粗颗粒材料制成时，即使地下水位较浅，覆盖层也趋于迅速去饱和。尾矿中地下水位的深度对单层覆盖物（由参考材料制成）的性能影响很小，但对尾矿中的水含量影响很大。在深水位的情况下，尾矿趋向于自然饱和，而在浅水位的情况下，尾矿可以保持高度饱和。从而，单层覆盖层的水文地质性质和地下水位的深度是两个因素，它们对覆盖层作为蒸发层（水分含量很低）或氧气层（水分含量高）的能力产生重大影响根据这些结果，对结合使用高水位的单层覆盖物的使用提出了一些建议。如果蓄水池中的地下水位较浅，则尾矿可以保持高度饱和。然后，单层覆盖物应用于减少蒸发，因此必须由易于快速饱和的粗颗粒材料制成。当地下水位较深时，尾矿会自然降低饱和度，而盖子应起到阻止氧气流向尾矿的作用。然后，覆盖层应由细颗粒的材料层制成，并置于较粗的材料层上。由于毛细管破裂的形成，即使在深水位的情况下，前者也可以保持高度饱和。

著录项

  • 作者

    Cosset, Geraldine.;

  • 作者单位

    Ecole Polytechnique, Montreal (Canada).;

  • 授予单位 Ecole Polytechnique, Montreal (Canada).;
  • 学科 Engineering Environmental.
  • 学位 M.Sc.A.
  • 年度 2010
  • 页码 251 p.
  • 总页数 251
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号