Water plays a critical role in the mining industry and this will apply in the post-mining era just as much as it did during the production years. When a mine is in operation the main concern – for both underground and opencast workings – is to ensure that the mining area is kept free of water in order to create a safe and properly functioning environment. These dewatering operations are mainly in the interest of the mine operators. However this situation changes when the production phase ceases and there is growing public interest in what is to happen with the former mining site. The issues that arise in this context mainly have to do with the impact of mine water on the groundwater bodies, the flooding of residual opencast mining cavities, the restoration of residual lakes and, essentially, the treatment of mine water with a view to preventing pollution and contamination. This year’s post-mining issue of Mining Report Glückauf is therefore devoted primarily to the subject of water management.
The RAG approach in this respect provides for a number of measures aimed at tackling the problem of rising mine water in the last remaining production areas of the Ruhr and Ibbenbüren coalfields in the years following the cessation of mining operations. Examples of mine-water management techniques employed in the Durham coalfield in the UK are compared with those used in the Lorraine coalfield in France in order to illustrate how important it is to make a correct assessment of the prevailing hydro-geological conditions.
As soon as lignite extraction operations have come to an end the lowered groundwater should in principle be restored as quickly as possible to its pre-mining level. Such an undertaking means making provisions for the impact that mining has had on the water landscape and also factoring-in the infrastructural and housing-development activities. This all generates a number of different hydrological tasks and responsibilities that in this edition are presented and discussed from the perspective of the Rhineland lignite mining area. Another contribution uses the example of the Lausitz coalfield to present the restoration measures that are being employed in the former lignite extraction areas and to explain how these operations are affected by periods of extremely dry weather, as experienced in the summer of 2018.
An opencast ore mining operation in Sweden is used to show how hydro-geochemical processes can influence water management practices. This paper also examines the practicality of recovering valuable metals from mine tailings and process water.
Water can also play a role in the development and after-use of former mining sites, with pumped-storage power plants being a potential example of this. Unfortunately the construction of these installations is not economically viable in the current market environment. Other examples of how abandoned mining land can be put to good use are provided in the form of RAG Montan Immobilien projects in the Ruhr coalfield and LEAG restoration schemes in the Lausitz lignite mining region.
With my best regards
Dipl.-Ing. Andreas-Peter Sitte
Chief Editor Mining Report Glückauf, Essen