Investigating the performance of a multilayer capillary barrier in mitigating acid mine drainage

Mining operations generate vast quantities of tailings, often leading to acid mine drainage (AMD), a major environmental concern. This study evaluates the performance of a multilayer capillary barrier system in controlling AMD at the Sungun copper mine through both experimental and numerical approaches. A glass column experiment was conducted with a 50 cm fine-grained layer sandwiched between two 30 cm coarse-grained layers. Results demonstrated that the fine-grained layer retained more than 85% saturation even under a 40-day drought period, reducing moisture loss by only 3%. The capillary barrier effectively restricted oxygen diffusion, maintaining oxygen penetration levels below 10-20 kg/day, significantly reducing sulphide oxidation. Numerical modelling using SEEP/W and CTRAN/W confirmed the experimental findings, with deviations of less than 2%. The study highlights the long-term effectiveness of capillary barriers in AMD prevention, making them a sustainable alternative for tailings management. These results provide critical insights for designing cost-effective and environmentally friendly mine closure strategies.