Acid mine drainage (AMD) often requires management long after mining operations have ceased. Cost-effective long-term passive treatment systems (PTS) are required for closure of mine sites. However, PTS research seldom defines well-constrained operational and financial parameters to enable confident decision making by mining companies. PTS are generally assumed to be a lower-cost alternative to active systems when used in favorable circumstances, but there is little objective information to define when they are more suitable than active treatment. Instead, general ‘rules-of-thumb’ for flow rates or acid loads are used to determine when PTS are best used. We used well-characterized AMD from multiple historic and active coal mine sites in New Zealand to test these rules-of-thumb from a financial perspective by modelling capital and operational costs over a 100 year timeframe. We present static and uncertainty-based cost assessments of a mussel shell reactor PTS compared to typical active AMD treatment systems at six mine drainage sources from the Brunner Coal Measures. We show that for expected AMD characteristics and duration of treatment, savings on operational costs with PTS can exceed the higher initial capital costs. In addition, the financial advantage of PTS over time may be achieved at flow rates and acidity loads that exceed the industry rules-of-thumb PTS limits. However, in some circumstances, cost projections for high up-front capital costs of purchasing all treatment media for the life span of the PTS is less favorable than discounted treatment media in active treatment systems over time. Understanding financial models of AMD treatment options during mine site design can help reduce the costs of operating and closing mine sites.

中文翻译：

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不确定性下主动和被动 AMD 处理系统的经济性能：来自新西兰 Brunner 煤系的案例研究

酸性矿山排水 (AMD) 通常需要在采矿作业停止后很久才进行管理。关闭矿场需要具有成本效益的长期被动处理系统 (PTS)。然而，PTS 研究很少定义约束良好的运营和财务参数，以使矿业公司能够做出自信的决策。在有利的情况下，PTS 通常被认为是主动系统的低成本替代方案，但几乎没有客观信息来定义它们何时比主动治疗更合适。相反，流速或酸负荷的一般“经验法则”用于确定何时最好使用 PTS。我们使用来自新西兰多个历史悠久且活跃的煤矿场址的充分表征的 AMD，通过对 100 年时间范围内的资本和运营成本进行建模，从财务角度测试这些经验法则。我们展示了一个贻贝壳反应器 PTS 的静态和基于不确定性的成本评估，与来自 Brunner 煤系的六个矿山排水源的典型主动 AMD 处理系统相比。我们表明，对于预期的 AMD 特征和治疗持续时间，使用 PTS 节省的运营成本可以超过更高的初始资本成本。此外，在超过行业经验法则 PTS 限制的流速和酸度负载下，PTS 随着时间的推移可以实现财务优势。然而，在某些情况下，随着时间的推移，在 PTS 的生命周期内购买所有处理介质的高前期资本成本的成本预测不如主动处理系统中的折扣处理介质有利。在矿场设计期间了解 AMD 处理方案的财务模型有助于降低运营和关闭矿场的成本。