Environmental Impact Of Mine Water From Chemical Extraction And Underground Uranium Mining - Straz Pod Ralskem, Czech Republic

During the second half of the 20th century, there was large-scale exploration and production of uranium ores in the Czech Republic. The biggest uranium deposit area was found in the North-Bohemian Cretaceous area in the mid-1960s. During 30 years of production, approximately 30,000 tons of uranium concentrate was produced. More than 15,000 drill holes were drilled in the area and almost 11,000 of them were cased and used as production and monitoring (hydrogeological) wells. Both classical underground (room and pillar) mining and in situ leaching (ISL) methods were used in the area. A mill and two tailings impoundments were also constructed in the area. Sulphuric acid was used as leaching agent to process ore from both mining methods. More than 4 million tons of sulphuric acid was injected into the ground for the 1SL method. This affected approximately 338 million m(3) of groundwater (limit 0,25 g.l(-1) SO42-) over an area of more than 26 km(2). The adverse influence of these activities has yet to be mitigated.