Alternative materials for engineered covers used to control acid mine drainage

今天采矿业面临的最严重的环境挑战之一是矿山废物处理区的复垦，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材料来改进覆盖技术，并分为两个不同的项目：1)膏岩作为覆盖材料的评估；2)工程覆盖层中膨润土基细粒材料的评估。*在项目1中，将制备、表征和测试不同废石与尾矿比例的膏岩。从水文地质性质的角度，将膏岩混合物的性能与利用混合物理论进行的理论预测进行比较。使用膏岩作为盖层材料的大型柱试验的结果将与现有的现场实验单元的结果进行比较。这两个装置都将被用来测量不饱和水的运动和气体的迁移，并将允许渗滤液的回收。物理模型(柱试验和野外实验单元)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(土壤-膨润土或土工合成粘土衬垫(GCL))在矿场附近无法获得传统细粒材料时，是有趣的覆盖材料。候选人最近的工作表明，岩石-膨润土混合物在短期内控制氧气迁移是有效的，但受到冻融循环的显著影响。在项目2中，将在实验室中对不同的土壤膨润土混合物进行详细的表征。根据表征的结果，将在温度控制室中进行仪表柱测试，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。GCL还将作为一种用于工程覆盖的细粒层在本项目中进行研究。候选人有权使用GCL作为现有掩护材料的矿场。将对完整的冻融循环和现场样品进行实验室测试(例如水和空气渗透性、微结构表征)，以评估GCL在产生AMD的矿场安装时控制流体(水和气体)移动的能力。*拟议的研究计划将为AMD产生的矿山废物处置区的复垦提供新的或改进的技术。这项工作将由HQP执行，他们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度重视的专家，同时支持行业可持续开采金属资源的目标。*

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.******