In-situ immobilisation of pollutants at Konigstein uranium ore mine of Wismut GmbH

摘要

The shrinkage-stope areas in the former Konigstein uranium ore mine constitute a significant source of pollution in the event of flooding. This applies not only to those areas where uranium was extracted by leaching with diluted sulphuric acid, but also to the unleached shrinkage stopes. The oxidation processes associated with sulphidic minerals mean that unleached sections of the mine will also generate acidic water with a high heavy-metal content. One way of reducing the quantity of releasable heavy metals and limiting the successive yield of contaminated solutions is to employ in-situ immobilisation through the use of BaSO_4-forming solutions. These can be produced in the presence of precipitant retarder by mixing Ba(OH)_2 and Na_2SO_3 solutions. Large-scale trials in shrinkage stopes at Konigstein mine have shown that the yield of pollutants is reduced by between 50 and 65 percent compared with washing. On the basis of these results the decision was taken in November 2001 to employ this technique for treating unleached shrinkage stopes in the southern district of the mine.