For acidic industrial solid wastes, an effective cover system is needed to reduce the rainwater infiltration and oxygen intrusion, thus reducing the generation of acid mine drainage (AMD) from wastes. A three-layered cover using low-permeability neutralized slag (abbreviated as TCNS) at the bottom of the traditional capillary barrier cover is proposed, in line with the novel concept of “waste protecting waste”. This study investigates the anti-seepage performance and oxygen barrier performance of TCNS under extreme climate conditions, through laboratory column test and numerical simulations. The results show that the water content of the neutralized slag (NS) layer remained stable (i.e., changed by less than 0.02) under either extremely wet condition or extremely dry condition. Under extremely wet condition (i.e., heavy rainfall corresponding to a 50-year return period), no water percolation was observed at the cover bottom; under extremely dry conditions, oxygen diffusion was greatly impeded, e.g., after 208 days of column test, the SO42− concentration in the AMD of the exposed (i.e., uncovered) waste rock was 4.6 times higher than that of the waste rock covered by TCNS. Numerical simulations considering two realistic climate conditions (i.e., humid and arid) showed that TCNS were effective in controlling water percolation and oxygen intrusion. The saturated permeability coefficient (ks) and initial saturation degree (Se) of the NS layer have significant effects on the performance of TCNS, i.e., decreasing ks or increasing Se can effectively reduce the water percolation and oxygen flux. In sum, TCNS is an effective barrier for controlling water percolation and oxygen intrusion, even in extreme climate conditions. Consequently, it can effectively minimize AMD leakage and thus reduce geological disasters such as groundwater contamination.

中文翻译：

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由中和炉渣组成的三层堆填区覆盖系统在极端气候条件下的防渗性能和氧气阻隔性能


对于酸性工业固体废物，需要一个有效的覆盖系统来减少雨水渗透和氧气侵入，从而减少废物产生酸性矿山排水 （AMD）。该文提出一种在传统毛细管屏障盖板底部使用低渗透性中和渣（简称TCNS）的三层盖板，符合“固废保护固废”的新概念。本研究通过实验室柱测试和数值模拟，研究了 TCNS 在极端气候条件下的防渗性能和氧屏障性能。结果表明：在极湿或极干条件下，中和渣层的含水率保持稳定（即变化小于0.02）。在极度潮湿的条件下（即对应于 50 年重现期的强降雨），覆盖底部没有观察到渗水;在极度干燥的条件下，氧气扩散受到极大阻碍，例如，经过 208 天的柱测试后，裸露（即未覆盖）废石的 AMD 中的 SO42− 浓度比 TCNS 覆盖的废石高 4.6 倍。考虑两种真实气候条件 （即潮湿和干旱） 的数值模拟表明，TCNS 在控制水渗透和氧气入侵方面是有效的。NS 层的饱和渗透系数 （ks） 和初始饱和度 （Se） 对 TCNS 的性能有显著影响，即降低 ks 或增加 Se 可以有效降低水的渗透和氧通量。总之，TCNS 是控制水渗透和氧气侵入的有效屏障，即使在极端气候条件下也是如此。 因此，它可以有效地最大限度地减少 AMD 泄漏，从而减少地下水污染等地质灾害。