Sustainable mine waste management: from microscale hydrogeochemical processes to macroscale prediction models

* 引言 * 矿山废弃物可通过释放具有有害酸度、金属（类）或其他污染物的劣质排水对环境产生负面影响。对矿山废物储存设施进行有效的长期管理，取决于能否预测矿山关闭后几十年内这些废水的渗透率和化学成分。为此，广泛的地球化学风化反应和耦合的物理输运过程需要定量地了解。矿物动力学，流出物成分和溶质形态在储存条件和废石类型之间差异很大，但迄今为止缺乏系统的表征。此外，我们将这种微观水文地球化学现象与实际宏观预测模型相结合的能力仍然有限：有效的废物管理仍然是采矿业面临的一项昂贵的技术挑战。该研究计划的目标是提高我们对矿山废物中关键水文地球化学过程的理解，并改进这些知识在矿山废物流出物质量预测模型中的应用。拟议的研究发生沿着两个主要主题：微观尺度的过程和宏观尺度的预测模型。这些主题的目标分别是：i）通过实验限制矿物学动力学和水溶性溶质形态对风化速率和污染物迁移率的控制，ii）使用反应性迁移建模和无量纲数分析创建和评估长期宏观预测模型。* 方法 * 使用受控的实验室实验，我们将研究风化率，矿物表面动力学和产生的废水质量从不同的废石材料在对比暴露条件下。通过分析废水中硫醇化类金属的水溶液形态，我们将确定这些污染物物种形成和降解的条件，从而揭示它们的环境持久性。其次，我们将监测和量化的矿物组合的演变，并获得动力学参数和指标代理散装废石的反应，最终可用于预测模型。最后，我们将进行反应性运输模拟，以评估不同的水文地球化学，矿物学和物理运输过程对整体排水质量作为废石类型和存储条件的函数的重要性。* 影响 * 该研究计划将利用世界一流的基础设施和与（国际）采矿从业者的广泛合作，培养几名研究生和本科生掌握先进的分析、实验和模拟技术。我们的研究结果将产生关于矿山废物水文地球化学的基础知识，以及改善矿山废物管理的实用见解，帮助加拿大公司在可持续采矿方面保持全球领先地位。

*INTRODUCTION* Mine wastes can negatively impact the environment through the release of poor-quality drainage with harmful levels of acidity, metal(loid)s or other contaminants. Effective long-term management of mine waste storage facilities is predicated on the ability to forecast seepage rates and the chemical composition of these effluents for decades beyond mine closure. For this, a wide range of geochemical weathering reactions and coupled physical transport processes needs to be quantitatively understood. Mineralogical dynamics, effluent composition and solute speciation vary greatly across storage conditions and waste rock types but lack systematic characterization to date. Furthermore, our ability to integrate such microscale hydrogeochemical phenomena with practical, macroscale prediction models is still limited: effective waste management remains a costly technical challenge for the mining industry. *OBJECTIVES* The objectives of this research program are to advance our understanding of critical hydrogeochemical processes in mine wastes and to improve the application of this knowledge in prediction models for mine waste effluent quality. The proposed research occurs along two major themes: microscale processes and macroscale prediction models. These themes, respectively, have the objectives to i) experimentally constrain the controls of mineralogical dynamics and aqueous solute speciation on weathering rates and contaminant mobility, and ii) to create and evaluate long-term macroscale prediction models using reactive-transport modeling and dimensionless numbers analyses. *METHODS* Using controlled laboratory experiments, we will study the weathering rates, mineralogical surface dynamics and generated effluent qualities from different waste rock materials under contrasting exposure conditions. By analyzing the aqueous speciation of thiolated metalloids in effluent, we will determine the conditions in which these contaminant species are formed and degraded and thereby shed light on their environmental persistence. Second, we will monitor and quantify the evolution of the mineral assemblages and derive kinetic parameters and indicator proxies for bulk waste rock reactivity that can ultimately be used in prediction models. Finally, we will perform reactive-transport simulations to assess the importance of distinct hydrogeochemical, mineralogical, and physical transport processes towards overall drainage quality as a function of waste rock type and storage conditions. *IMPACT* This research program will train several graduate and undergraduate students in advanced analytical, experimental, and simulation techniques, using world-class infrastructure and extensive collaboration with (international) mining practitioners. Our results will produce fundamental knowledge on mine waste hydrogeochemistry as well as practical insights for improved mine waste management, helping Canadian companies to remain global frontrunners in sustainable mining.