Water content plays a critical yet ambivalent role in the physical and geochemical stability of mine tailings and waste rock, but its effects on individual chemical weathering reactions (dissolution and precipitation) and bulk water quality remain poorly understood. We experimented with synthetic waste rock to quantitatively reconcile modal and textural mineralogical parameters (mineral size, association, and liberation) with leachate quality at different water saturation levels (5–100%). Leachate pH consistently decreased from a 13-week average of 6.14 at 100% saturation to 5.37 at 5% saturation. Simultaneously, mineralogical analyses revealed a reduction in the size of carbonate phases over the course of weathering, decreasing from 200 µm to 145 µm as water saturation increased from 5% to 100%, which could be a contributing factor to more alkaline pH in samples with higher water saturation. Total concentrations of iron (Fe) and copper (Cu) in solution increased with lower moisture, with Cu concentrations increasing 24-fold in samples at 5% saturation compared to full saturation. In contrast, arsenic (As) concentration increased with higher moisture levels, which we attribute to reduced galvanic protection of As-bearing pyrite from oxidation. Multivariate statistical evaluation allowed us to uncover correlations between water chemistry and mineralogical data (i.e., sulfide associations or phase perimeters) and to explain chemical differences between samples, particularly those at 100% and 5% water saturation. Our findings underscore the importance of conducting quantitative mineralogical investigations on mine waste materials and considering their stored water content in the formulation of mine waste management strategies.

中文翻译：

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含水量对风化矿山废石矿物学和排水质量动态的影响


水含量在尾矿和废石的物理和地球化学稳定性中起着至关重要但又矛盾的作用，但其对个别化学风化反应（溶解和沉淀）和整体水质的影响仍然知之甚少。我们对合成废石进行了实验，以定量协调模态和结构矿物学参数（矿物尺寸、缔合和释放）与不同水饱和度水平（5-100%）的渗滤液质量。渗滤液 pH 值持续下降，从 100% 饱和度时的 13 周平均值 6.14 降至 5% 饱和度时的 5.37。同时，矿物学分析显示，在风化过程中，碳酸盐相的尺寸减小，随着水饱和度从 5% 增加到 100%，碳酸盐相的尺寸从 200 µm 减小到 145 µm，这可能是样品中 pH 值偏碱性的一个因素。较高的含水饱和度。溶液中铁 (Fe) 和铜 (Cu) 的总浓度随着湿度的降低而增加，与完全饱和相比，5% 饱和度样品中的铜浓度增加了 24 倍。相比之下，砷 (As) 浓度随着水分含量的增加而增加，我们将其归因于含砷黄铁矿免受氧化的电流保护减少。多元统计评估使我们能够揭示水化学和矿物学数据（即硫化物关联或相周长）之间的相关性，并解释样品之间的化学差异，特别是在 100% 和 5% 水饱和度下的样品。我们的研究结果强调了对矿山废料进行定量矿物学调查并在制定矿山废料管理策略时考虑其储存的水含量的重要性。