Optimization of filtered tailings deposition and reclamation for improved physical and chemical stability

最近在Mount Polley、Samarco、Cadia Valley和Brumadinho矿山发生的尾矿坝溃坝事故，严重破坏了传统的尾矿沉积模式。目前，大多数指南都在积极考虑和推荐采用过滤式尾矿沉积等新方法来提高尾矿储存设施的物理稳定性。与传统的泥浆尾矿相比，尾矿脱水确实有许多优点，有助于降低岩土工程风险和大坝溃坝的后果。然而，若干不确定因素，特别是与大气的相互作用和产生受污染的矿井排水的危险，迄今为止在某种程度上减缓了这项技术的应用，特别是在加拿大。此外，在实践中，对过滤后的固体燃料的长期行为和回收进行了相对有限的研究，而且该领域的大多数经验都是在已经运行时获得的。然而，由于时间是控制过滤后的尾矿水文岩土和地球化学行为的最关键因素，干堆将从更好的规划中显著受益。因此，“封闭性设计”的概念比以往任何时候都更加重要。因此，拟议的DG研究计划的主要目标是制定解决方案并优化反应性过滤尾矿处置规划，以更好地控制其短期和长期的水文地球化学和岩土稳定性。更具体地说，研究方案将分为两个主要的互补轴：(1)优化过滤后的尾矿沉积，以降低生产过程中酸性矿水（AMD）产生的风险（考虑运营约束）；(2)为过滤后的TSF临时和最终回收开发创新解决方案。该研究项目将是高度跨学科的，并将为过滤后的TSF的可持续处置和回收提供创新的解决方案。该研究将通过HQP培训（3名博士，3名硕士和2名本科）进行，他们将成为该领域未来的专家。公平、多样性和包容性将是HQP培训计划的核心。该研究计划将包括实验室测试、实地工作和先进的数值模拟，并将有助于开发和适应采矿环境的创新方法方法。这项研究将提高人们对过滤后尾矿的短期和长期水文地球化学行为的认识。研究结果应该引起许多加拿大矿山的兴趣，这些矿山认为干堆是减少岩土工程风险的一种方法，但由于不确定因素和缺乏解决酸性矿井排水的技术解决方案，因此不愿采取这条道路。在加拿大发展过滤后的尾矿处理将有助于减少今后尾矿堆坝发生故障的风险，从而改善邻近社区的安全，保护环境和整个社会的财富。

Recent tailings dam failures at Mount Polley, Samarco, Cadia Valley and Brumadinho mines have deeply disrupted the conventional tailings deposition paradigm. New approaches such as filtered tailings deposition are now actively considered and recommended by most guidelines to improve the physical stability of tailings storage facilities (TSF). Dewatering tailings has, indeed, many advantages over traditional slurry tailings, and contributes to reducing geotechnical risk and consequences of dam failures. However, several uncertainties, and in particular the interactions with the atmosphere and the risk for contaminated mine drainage generation, have somewhat slowed down the application of the technique so far, especially in Canada. Also, in practice, relatively limited research has been conducted on filtered TSF long-term behaviour and reclamation, and most of the experience in the field was gained while already operating. Dry stacking would, however, significantly benefit from better planning, as time is the most critical factor controlling filtered tailings hydrogeotechnical and geochemical behaviour. The concept of "Designing for closure" has thus become more relevant than ever. The main objective of the proposed DG research program is therefore to develop solutions and optimize the planning of reactive filtered tailings disposal to better control their hydrogeochemical and geotechnical stability in the short and long term. More specifically, the research program will be divided into two main complementary axes: (1) Optimization of filtered tailings deposition to reduce the risk of acid mine drainage (AMD) generation during operations (considering operational constraints); (2) Development of innovative solutions for temporary and final reclamation of filtered TSF. The research program will be highly multidisciplinary and will provide innovative solutions for the sustainable disposal and reclamation of filtered TSF. The research will be performed through HQP training (3 PhD, 3 MSc and 2 UG) who will become tomorrow's experts in the field. Equity, diversity, and inclusion will be central in the HQP training plan. The research program will include laboratory tests, field work, and advanced numerical simulations, and will contribute to developing and adapting innovative methodological approaches to mining environment. This research will improve knowledge about short- and long-term hydrogeochemical behaviour of filtered tailings. Research outcomes should be of interest for many Canadian mines which consider dry stacking as a way to decrease the geotechnical risks but hesitate to take this path because of uncertainties and lack of technical solutions to tackle acid mine drainage. Developing filtered tailings disposal in Canada would contribute to reducing the risk of TSF dam failures in the future, thus improving the safety of the neighbouring communities, the protection of the environment and the wealth of the society in general.