Quantitative forecasts of acid mine drainage (AMD) production are important for remediation planning. Reactive transport simulations corresponding to a detailed sampling location at a covered legacy tailings impoundment in northern Ontario, Canada, were conducted to quantitatively assess the predominant hydrogeochemical reactions. The simulations span the period from the end of tailings deposition (circa 1970) to early 2020, 12 years after remediation by a five-layer composite cover. The conceptual model of uncovered tailings weathering and subsequent geochemistry of the covered tailings system was implemented in 1D using the multi-component reactive transport code MIN3P. Transient monthly infiltration, post-cover boundary condition changes, and a dynamic temperature regime were incorporated. The shrinking core model, including parallel O_2(aq) and Fe³⁺ oxidation reactions for the waste rock in the cover and the underlying tailings, was implemented to simulate the oxidation of As-bearing pyrite, chalcopyrite, and sphalerite. Primary carbonate and aluminosilicate host minerals promoted acid-neutralization reactions. Precipitation of secondary phases and sorption/desorption of Cu, Zn, and arsenite were incorporated into the model. The overall agreement between key simulated and field-measured post-cover aqueous geochemical parameters suggests that the conceptual model captured the primary hydrogeochemical processes in the covered tailings. A lack of reliable data on initial tailings mineralogy and pre-cover hydrogeochemistry increased simulation uncertainty. Simulated reaction rates indicate that where intact, the cover decreased sulfide oxidation rates by both O_2(aq) and Fe³⁺ and improved pore-water quality over time. Simulation results indicate that elevated concentrations of Zn and As are likely to persist in the tailings regardless of cover performance, whereas concentrations of Cu and Al are the parameters most sensitive to cover effectiveness.

酸性矿山排水 (AMD) 产量的定量预测对于修复规划非常重要。对加拿大安大略省北部有盖遗留尾矿库的详细采样位置进行了反应输运模拟，以定量评估主要的水文地球化学反应。模拟的时间跨度从尾矿沉积结束（大约 1970 年）到 2020 年初，即五层复合覆盖层修复后的 12 年。使用多组分反应输运代码 MIN3P 以一维方式实现未覆盖尾矿风化和随后覆盖尾矿系统地球化学的概念模型。瞬时每月渗透、覆盖后边界条件变化和动态温度状况都被纳入其中。收缩核心模型，包括覆盖层废石和下伏尾矿的平行O _2(aq)和Fe ³⁺氧化反应，用于模拟含砷黄铁矿、黄铜矿和闪锌矿的氧化。原生碳酸盐和铝硅酸盐主体矿物促进酸中和反应。模型中纳入了第二相的沉淀以及铜、锌和亚砷酸盐的吸附/解吸。关键模拟和现场测量的覆盖后水地球化学参数之间的总体一致性表明，概念模型捕获了覆盖尾矿中的主要水文地球化学过程。缺乏关于初始尾矿矿物学和预覆盖水文地球化学的可靠数据增加了模拟的不确定性。模拟反应速率表明，在完好无损的情况下，覆盖层降低了 O _2(aq)和 Fe ³⁺的硫化物氧化速率，并随着时间的推移改善了孔隙水质量。模拟结果表明，无论覆盖性能如何，尾矿中锌和砷的浓度可能持续升高，而铜和铝的浓度是对覆盖效果最敏感的参数。