In-pit disposal of reactive mine wastes: control of acid mine drainage and reclamation

采矿业最关键的问题之一仍然是对作业期间产生的大量固体废物(尾矿和废石)的管理和安全处置。这些材料通常含有硫化物，与氧气(空气)和水接触时会被氧化，产生含有高浓度硫酸盐和重金属的酸性水(称为酸性矿山排水，AMD)。拟议的研究方案旨在开发在露天矿处置采矿废物的工具和技术，以减少对环境的影响和处置地点的足迹。这种方法在一些采矿项目中得到了应用，但要充分优化这项技术，还需要进一步的研究。这些假设是，坑内处置可用于限制AMD的产生风险，提高处置材料的整体长期地球化学和岩土稳定性，稳定坑壁，减少建造新蓄水池或废石堆的需要，并改善场地的美观。然而，该方法面临一些挑战，特别是在处置废物的化学稳定性、水流的控制和与周围环境的交换以及处置本身的操作方面。 拟议的DG研究方案的长期目标是合理和优化活性矿山废物的坑内处置，以便随着时间的推移更好地控制其水文地球化学和岩土稳定性。该研究计划将分为两个主要的互补项目：a.优化露天矿的采矿废物处理，以降低作业期间产生AMD的风险；b.长期关闭回填露天矿。项目A将把“设计封闭”的原则扩展到尾矿(A1)和废石(A2)的坑内处置。项目B的主要目标将是研究工程覆盖系统的行为和性能，以防止在回填坑中长期产生AMD。 这项工作将通过HQP培训(2名博士、2名MSCA和4名UG)进行。每个项目将包括实验室测试(定性和物理模型)和实地工作。数值模拟也将是研究计划的重要部分。 拟议的DG研究计划雄心勃勃，具有很高的原创性，因为它旨在通过整合运营和环境方面来发展坑内处置。它将为优化处置提出稳健的解决方案。由于近几年(以及可能即将到来)露天矿的增多，井下处理变得越来越重要。矿业公司对替代处置解决方案有着浓厚的兴趣，这种解决方案既能满足处置场地的岩土和地球化学稳定性要求，又能限制环境足迹。拟议的研究计划将回答其中一些新的挑战。

One of the most critical issues for the mining industry remains the management and safe disposal of the important quantities of solid wastes (mine tailings and waste rocks) produced during the operations. These materials often contain sulfides which can oxidize upon contact with oxygen (air) and water, producing acidic waters with high concentrations of sulfates and heavy metals (known as acid mine drainage, AMD). The proposed research program aims at developing tools and techniques for the disposal of mining wastes in open pits in order to reduce the environmental impact and footprint of disposal sites. This approach is used in a few mining projects but further research is required to fully optimize the technique. The assumptions are that in-pit disposal can be used to limit the risk for AMD generation, improve the overall long term geochemical and geotechnical stability of the disposed materials, stabilize the walls of the pit, reduce the need for building new impoundments or waste rock piles, and improve the aesthetics of the sites. There are, however, several challenges to the method, particularly regarding the geochemical stability of the disposed wastes, the control of water flow and exchanges with the surrounding environment, and the operational aspects of the disposal itself. The long term objective of the proposed DG research program is to rationalize and optimize the in-pit disposal of reactive mine wastes to better control their hydrogeochemical and geotechnical stability over time. The research program will be divided into two main complementary projects: A. Optimization of the disposal of mining wastes in open pit mines to reduce the risk of AMD generation during operations; B. Long term closure of backfilled open pits. Project A will extend the principle of “Designing for Closure” to in-pit disposal of tailings (A1) and waste rock (A2). The main objective of Project B will be to study the behaviour and performance of engineered cover systems to prevent long term production of AMD in backfilled pits. The work will be performed through HQP training (2 PhD, 2 MScA and 4 UG). Each project will include laboratory tests (characterization and physical modelling) and field work. Numerical simulations will also be an essential part of the research program. The proposed DG research program is ambitious and highly original because it aims at developing in-pit disposal by integrating operational and environmental aspects. It will propose robust solutions for optimized disposal. In-pit disposal is becoming more and more important due to the multiplication of surface mines in recent (and probably upcoming) years. There is a strong interest among mining companies for alternative disposal solution that will both fulfil the geotechnical and geochemical stability requirements of disposal sites, and limit the environmental footprint. The proposed research program will answer some of these new challenges.