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管理和安全处置作业期间产生的大量固体废物（矿山尾矿和废石）。这些材料通常含有硫化物，与氧气（空气）和水接触后会氧化，产生含有高浓度硫酸盐和重金属的酸性水（称为酸性矿井排水，AMD）。拟议的研究方案旨在发展在露天矿坑中处置采矿废料的工具和技术，以减少处置地点的环境影响和足迹。这种方法已在一些采矿项目中使用，但需要进一步研究以充分优化该技术。假设是，坑内处置可用于限制AMD产生的风险，改善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，并改善场地的美学。然而，该方法面临着若干挑战，特别是关于所处置废物的地球化学稳定性、对水流和与周围环境交换的控制以及处置本身的操作方面。

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.