Porosity evaluation of fine particles in mine tailing based on electrical conductivity by considering surface conduction

Mine-tailing dams have failed abruptly and frequently in recent years. This is notwithstanding the development and application of site investigation and monitoring techniques. The aim of this study was to develop a robust electrical conductivity formula based on Archie’s equation for fine particles in partially saturated mine-tailing dams. Three specimens of uncoated silt, haematite-coated silt and samples collected from actual mine tailings (Minnesota silt) were prepared in a temperature-compensated cell installed with four electrodes. The test results showed that the saturation exponent increased with respect to the pore water conductivity up to 1 S/m. In addition, the saturation exponent showed higher values in the order of Minnesota silt, haematite-coated silt and uncoated silt owing to the different wettabilities. From the comparative analysis, uncoated and haematite-coated silt differed only in their specific surface areas. Meanwhile, the surface conduction term of Minnesota silt was influenced by both specific surface area and zeta potential. In addition, the newly defined Archie’s ‘ms’ considering the surface conduction term fits effectively with a high R2 value. Thus, the surface conduction term should be considered for estimating the porosity by measuring the electrical conductivity of iron mine tailings.