Alternative materials for engineered covers used to control acid mine drainage

当今矿业面临的最严重的环境挑战之一是矿山废物处理区的回收，特别是当它们含有可产生酸性矿山废水（AMD）的硫化物矿物时。拟议的研究计划旨在通过使用替代材料作为覆盖部件来改进覆盖技术，并分为两个不同的项目：1)评估膏体岩石作为覆盖材料；2)工程盖板中膨润土基细粒材料的评价。****在项目1中，将制备不同废石与尾矿比例的膏体岩，并对其进行表征和测试。在水文地质性质方面，将膏体岩石混合物的性能与使用混合物理论所作的理论预测进行比较。采用膏体岩石作为覆盖材料的大型柱试验结果将与现有现场试验单元的结果进行比较。这两种装置都将测量不饱和水运动和气体迁移，并将允许渗滤液被回收。物理模型（柱试验和现场实验池）的结果将与水文地球化学数值模型的结果进行比较。****膨润土基细粒材料（土-膨润土或土工复合粘土衬里（GCL））是在矿场附近无法获得传统细粒材料时作为覆盖材料的有趣选择。候选人最近的工作表明，岩石-膨润土混合物在短时间内有效地控制氧气迁移，但受冻融循环的影响很大。在项目2中，将在实验室中进行不同土壤膨润土混合物的详细表征。根据表征结果，将在温控室中进行仪器柱试验，以评估膨润土基覆盖物在冻融循环中控制氧气和水迁移的性能。在这个项目中，GCL也将作为工程盖板中使用的细粒度层进行研究。候选人可以进入一个矿场，在那里GCL被用作现有的掩护材料。将对完整的、冻融后循环和现场样品进行实验室测试（例如，水和空气渗透性、微观结构表征），以评价在产生amd的矿场安装GCL后控制流体（水和气体）运动的能力。****拟议的研究方案将为产生amd的矿山废物处理区的回收提供新的或改进的技术。这项工作将由HQP执行，HQP将从这次培训中受益，成为具有减少采矿对环境影响的知识和能力的高价值专家，同时支持该行业可持续开发金属资源的目标。******

One of the most serious environmental challenges facing the mining industry today is the reclamation of mine waste disposal areas, especially when they contain sulphide minerals that can produce acid mine drainage (AMD). The proposed research program seeks to improve cover technologies through the use of alternative materials as cover components, and is divided into two distinct projects: 1) assessment of paste rock as cover material; 2) assessment of bentonite based fine grained materials in engineered covers.****In Project 1, paste rocks with different waste rock to tailings ratios will be prepared, characterized, and tested. The performance of the paste rock mixtures will be compared, in terms of hydrogeological properties, with theoretical predictions made using Mixture theory. The results of large-scale column tests, in which paste rocks are used as cover material, will be compared with the results from existing field experimental cells. Both set-ups will be instrumented to measure unsaturated water movement and gas migration, and will allow for leachates to be recovered. Results obtained from the physical models (column tests and field experimental cells) will be compared with those from hydrogeochemical numerical models.****Bentonite-based fine-grained materials (soil-bentonite or geocomposite clay liner (GCL) are interesting options as cover materials when traditional fine-grained materials are not available near the mine site. Recent work performed by the candidate demonstrated that rock-bentonite mixtures are efficient in controlling oxygen migration over short periods, but are significantly influenced by freeze-thaw cycles. In Project 2, a detailed characterization of different soil bentonite mixtures will be performed in the lab. Based on the results of the characterizations, instrumented column tests in a temperature-controlled chamber will be performed to assess the performance of bentonite-based covers in controlling oxygen and water migration when exposed to freeze-thaw cycles. GCL will also be investigated in this project as a fine-grained layer used in engineered covers. The candidate has access to a mine site where GCL is used as an existing cover material. Laboratory tests (e.g., water and air permeability, microstructural characterization) on intact, post-freeze-thaw cycles, and in situ samples will be performed to evaluate the capacity of GCL to control fluid (water and gas) movement when installed at AMD-generating mine sites.****The proposed research program will provide new or improved techniques for the reclamation of AMD-generating mine waste disposal areas. The work will be performed by HQP, who will benefit from this training by becoming highly-valued specialists with the knowledge and ability to reduce the environmental impacts of mining, while supporting the industry's goal of sustainable exploitation of metal resources.******