Verhalten des Radiums im Flutungsprozeß des Uranbergwerks Königstein

The interaction of radium with characteristic sediments of the upper Saxon Elbe river valley was investigated with the
aim to provide key data for transport modelling within the framework of mining site restoration. Adsorption
measurements therefore were carried out on site-specific sediments (different kinds of sandstone, claystone and lime
marl) using (1) acidic mine water coming from sulfuric acid residues of the former in-situ leaching process, (2)
groundwater that is inflowing into the mine and (3) mixtures of both which simulates certain stages of the mine flooding process. The distribution ratios were determined by batch experiments using an eight-week equilibration at aquifer temperature (14 °C). Radium adsorption from acidic mine water onto different kinds of sandstone is characterized by high distribution ratios (3400 mL/g). When contacted with groundwater, the sorption is decreased more than 20-fold (60-180 mL/g). For claystone and lime marl the distribution ratios amount to 130 and 480 mL/g, respectively, and they are nearly constant in the mine flooding process. The main adsorption mechanisms on the leached sandstone and the clayey sediments were identified as coprecipitation and ion exchange, respectively. The long-term migration behaviour in the aquifers of the south-east Saxon Elbe basin was calculated on the basis of Hadermanns' equation, considering retardation, dispersion and radioactive decay.