Abstract The hydrogeochemical behavior of highly reactive tailings with no or very low neutralizing capacity and their hydrogeochemical response when covered by a cover with capillary barrier effects (CCBE) were evaluated in laboratory columns. The hydrogeochemical response of highly reactive tailings under wetting-drying cycles and saturated conditions was also simulated using the MIN3P code, a finite volume model for coupled groundwater flow, oxygen diffusion and multi-component reactive transport. Laboratory tests were conducted for approximately 18 wetting and drying cycles, over a period of one and a half years. A numerical simulation model was validated using laboratory results of uncovered highly reactive tailings under wetting and drying cycles conditions. The acceptable agreement between the geochemical observations in the laboratory and the numerical simulations shows that MIN3P can simulate the hydrogeochemical response of highly reactive tailings (initially very acidic) under laboratory experimental conditions and can make realistic predictions. The laboratory hydrogeochemical response of highly reactive tailings covered by a CCBE and the numerical modeling results of highly reactive tailings under saturated conditions (an equivalent CCBE oxygen barrier) indicated a decrease in the concentration of sulfate and most metals in the leachate compared to uncovered highly reactive tailings, indicating that both scenarios decreased sulfide oxidation. The simplified approach for geochemical modeling of saturated reactive tailings evaluated in this paper could be used to determine the required oxygen barrier efficiency to reach the target effluent geochemistry as a preliminary stage of reclamation design.

中文翻译：

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不同环境条件下高反应性尾矿地球化学行为的反应输运模型

摘要 在实验室柱中评估了没有或非常低中和能力的高反应性尾矿的水文地球化学行为及其被毛细管屏障效应 (CCBE) 覆盖时的水文地球化学响应。还使用 MIN3P 代码模拟了高反应性尾矿在干湿循环和饱和条件下的水文地球化学响应，这是一种耦合地下水流、氧扩散和多组分反应输运的有限体积模型。在一年半的时间里，对大约 18 个润湿和干燥循环进行了实验室测试。使用在润湿和干燥循环条件下未覆盖的高反应性尾矿的实验室结果验证了数值模拟模型。实验室地球化学观测结果与数值模拟结果一致表明，MIN3P 可以模拟实验室实验条件下高活性尾矿（初始酸性很强）的水文地球化学响应，并能做出符合实际的预测。CCBE 覆盖的高反应性尾矿的实验室水文地球化学响应和饱和条件（等效 CCBE 氧屏障）下高反应性尾矿的数值模拟结果表明，与未覆盖的高反应性尾矿相比，浸出液中硫酸盐和大多数金属的浓度降低尾矿，表明两种情况都减少了硫化物氧化。