Assessment of Metal Equipment Corrosion and Water Pollution in Flooded Ukrainian Mines

In this paper we present the results of the modeling of iron release into mine water caused by corrosion of metal equipment in the flooded "Centralna" coal mine (Myrnohrad, Ukraine). The mine equipment includes mechanized supports, longwall shearers, conveyors, pipelines, and electrical systems, which remain flooded after mine closure. Based on calculations of the mass loss of flooded metal equipment, we developed a long-term corrosion forecast and groundwater saturation with iron. Hydrogeochemical analysis of groundwater (pH = 7.7, electrical conductivity = 3610 μS/cm, Fe2+ = 0.13 mg/L, Na+ = 620 mg/L, SO42− = 1030 mg/L) indicates that the corrosion rate was estimated under near-neutral and moderately mineralized conditions. To assess possible changes in the accumulation of ferrous iron in the groundwater of the flooded "Centralna" coal mine, three corrosion scenarios were modeled: a constant rate of iron dissolution, a decreasing rate, and an increasing rate of iron dissolution. Model results suggest that after 10 years, predicted Fe2+ concentrations could reach 8.289 mg/L, which is about 40 times higher than the maximum permissible iron concentration in drinking water.