Examination of mine waters of the Olsi-Drahonin uranium deposit

The research task in the framework of Czech Science Foundation grant project No. 105/06/0127 'Non-traditional utilisation of uranium deposits after underground mining completion' deals with the possibilities for the intensive utilisation of mine waters from closed and flooded uranium mines as a source of uranium with the additional effect of shortening the time period necessary for the purification of mine waters discharged into surface watercourses. Participants in the project are The Institute of Geological Engineering of the Faculty of Mining and Geology, VSB - Technical University of Ostrava, the Science Faculty of Masaryk University in Brno and DIAMO state enterprise. Information about the goals of the research project, the project methodology and the progress of problem solution as well, was presented in previously. In the year 2007 the research work was concentrated on the selected type locality of the OIsi-Drahonin uranium deposit. On basis of gathered data about the deposit and taken rock samples the analysis of uranium ore oxidizing process and general progress of rock mass weathering was carried on, mathematical modelling of both the mine water flow in the flooded OIsi-Drahonin deposit and the transport of substances in mine waters was made up, and a hydrogeological well in the centre of the deposit was drilled to find out the characteristic of mine waters. The hydrogeological well, or pumping test actually has confirmed the first hypothesis of mine waters accumulation in a flooded mine which might be suitable for utilisation as a secondary source of uranium. While the content of uranium in the period of the deposit exploitation had reached 4,5 mg.l-1 maximally, and after flooding the mine it raised up to 13,1 mg.l-1, now after mine water regime stabilisation the content of uranium in quasi-stagnating waters, sampled in the well, was detected on the grade of 17,5 mg.l-1. (author)