Amelioration of permeable soil with green liquor dregs for the construction of sealing layers for mine waste storage facilities

¹ Luleå University of Technology, 87187 Luleå, Sweden
² Boliden Mineral, Boliden, Sweden
³ Department of Environment and Mineral Resources, Greenland Institute of Natural Resources, 3900 Nuuk, Greenland
⁴ Research Institute on Mines and the Environment (RIME), Polytechnique Montreal, Canada

^* Corresponding author: ida.kronsell@ltu.se

Abstract

Mining of sulfidic ore generates acidic waste which often leads to the generation of acid rock drainage (ARD) having an adverse impact on aquatic flora and fauna. Engineered multilayer cover is one of the commonly used methods to prevent oxygen from being transported to mine waste. The sealing layer has a key function in the cover, thanks to its high water retention capacity and a low hydraulic conductivity, which enable the layer to remain near water saturation, effectively hindering oxygen diffusion. When adequate material is not available improvement of local soil material with a sealing agent is principally the only option to produce sealing layer material. Apart from bentonite clay, Green Liquor Dregs (GLD), a waste from the pulp and paper industry, have the ability to reduce the oxygen diffusion when mixed to granular soil, improving the water retention capacity of the blend. Experience from the development of Till/GLD-blends for the construction of sealing layers is compiled to address issue related to soil amelioration using waste with focus on material variation and quality control. The presentation focuses on the opportunities and challenges for the establishment of a circular system based on reutilization of a waste, herein GLD for improvement of soil’s geotechnical property.