Improving Mine Water Quality by Low Density Sludge Storage in Flooded Underground Workings

摘要

This paper discusses the chemical and physical characteristics of low density sludge (LDS) and its interaction with mine water in a flooded German underground fluorite mine. The highly hydrous nature of the sludge (11.5-17 % solids), its rather low sedimentation rate, and its thixotropic viscosity were confirmed. The interaction of LDS and mine water was tested in the laboratory in batch experiments and modelled with PHREEQC. Mine water quality improved through contact with the LDS sludge: the total alkalinity and pH of the water increased and its iron concentration and total acidity decreased. Storage of sludge in a flooded mine could be a sustainable tool for both the handling of LDS and improvement of mine water quality, even when the LDS represents less than 1 % of the total mine water volume. No polymer flocculants from the LDS treatment plant were found in the discharged mine water.