Water drainage in the German coal mining after the close-down in 2018

摘要

As from 2018, coal mining in the Federal Republic of Germany will be terminated. The last mine will stop coal extraction. Nevertheless, for the operators an important task remains:Rain water still continues to accumulate in the depths of the mines. This may enrich with minerals and reach a high salinity. In order to avoid contaminating the groundwater, this mine water needs to be pumped above ground.In conventional water drainage, this task is done by underground dry-installed pumps. Which means ventilation, transport, and personnel must be maintained and the annual operating costs are quite substantial.A new concept involves replacing the underground dry-installed pumps with floodable submersible pumps. The mine water can be allowed to rise to a level that would still be below the groundwater horizons so that mixing would definitely not be possible.This concept's benefits are obvious. Ventilation and transport are no longer required when using submersible pumps. Along with the now lowered power consumption of the pumping system, this leads to a significant reduction of the total operating costs.For its technical implementation, cladding tubes, into which the submersible pumps can be lowered, will be introduced into existing mine shafts. In the former Walsum mine, for instance, two double-suction, and thus axial thrust free, submersible motor pumps are installed to pump the highly saline mine water at a depth of 800m.Because changing the pump could be extremely complex and expensive because of the installation depth, highest operational safety, a long service life and ease of use - even under the harshest conditions - must be imperative.