Hydrogeochemistry of the Abandoned Sulfide Mines of the Middle Urals (Russia)

Abstract

Many years after completion of mining, acidic groundwater continues to accumulate within the abandoned chalcopyrite mines of the Urals (Russia). The process of its generation is not steady: there is an initial large accumulation with a subsequent gradual decline over the years. The content of water mineral components after the cessation of mining is 2 to 3 times higher than while mines were still in use. In addition to the oxidation of sulfides, there is a dissolution of secondary minerals, formed in the artificial zone of hypergenesis due to the process of dewatering. With the use of inverse modeling, we determined the composition of the rocks that lead to the formation of acid groundwater in the flooded mines of the Urals at various stages of their existence. During mining, the generation of acid mine water occurs in the oxidation of 33 mmol/kg sulfides (pyrite + chalcopyrite + sphalerite). In the postmining phase, the maximum values of the solute (after 10 months) can be formed by dissolving 158 mmol/kg sulfides. In 90 months after the release of groundwater to the surface, the intensity of oxidation of the sulfides is reduced, up to 57 mmol/kg.