Arsenic Removal from Alkaline Mine Drainage Using Waste Sludge: Pilot-Scale Experiments at an Abandoned Mine in South Korea

초록

Mine drainage exhibits site-specific characteristics, and its composition varies notably depending on the surrounding geological and environmental conditions. This variability raises the need for field-based empirical studies and the development of treatment methods tailored to specific properties. Here, field pilot-scale experiments were conducted to investigate the efficiency of As removal from alkaline mine drainage at an abandoned mine in north Gyeongsang Province, South Korea. The mine drainage, with a pH of 8.2 and an average As concentration of 400 mu g/L, was treated using adsorption processes in pilot-scale column experiments. Four iron-based adsorbents were evaluated: raw coal mine drainage sludge (CMDS), CMDS coated with polyurethane (CMDS-PU), CMDS pelletized into a cylindrical shape (CMDS-PE), and granular ferric hydroxide (GFH), a commercially available iron-based material, used as a control. Detailed physicochemical characterization revealed that while CMDS had a high specific surface area and iron content, its adsorption performance was inhibited by channeling, leading to an early breakthrough at 1,871 bed volumes (BV). In contrast, CMDS-PU and CMDS-PE exhibited improved flow distributions, with the CMDS-PU column reaching a breakthrough after processing 5,242 BV. Concentrations of As in the effluent from the CMDS-PE and GFH columns were maintained < 50 mu g/L, the regulatory As discharge standard, throughout the experimental period. A CMDS environmental assessment confirmed that the potential for leaching harmful substances was low under the experimental conditions. This site-specific study identified treatment methods tailored to the mine drainage properties and assessed the potential of using mining waste-derived materials for cost-effective and sustainable mine drainage treatments specifically for alkaline mine drainage.

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