Flooding of the Königstein underground mine : hydraulic and geochemical modelling approach

Abstract

Uranium was produced in the Königstein mine by conventional mining as well as underground in-situ leaching activity from a sandstone aquifer between 1964 and 1990. Due to the chemical mining and the secondary effect of pyrite oxidation the pore water of the rock matrix has a pH of less than 2 and a high content of among others uranium, iron and sulphate. Another source of contaminants are soluble minerals which precipitated in open mine workings. They will dissolve during the flooding and generate a contaminant peak right after the beginning of the flooding of open mine spaces. The remediation of the mine should aim for the restoration of the natural groundwater flow in the regional flow system.