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The last post-mining edition of Mining Report Glückauf (issue 3/2019) focused on the problem of water management at former mine sites. Here the main challenge was how to deal with the volume of water arising in various sectors of the extractive industry after the cessation of mining operations. In this latest edition we shall be turning our attention to the current situation in respect of mine water pumping and management in the former Ruhr coalfield.

The end of active coal mining in North Rhine-Westphalia in December 2018 signalled the start of a post-mining phase whose impact is set to be extensive rather than selective in nature. Here mine water management has now become an eternity task and RAG Aktiengesellschaft, as the former operating company responsible for the coal industry, was quick to respond

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With my best regards // Mit freundlichem Glückauf
Dipl.-Ing. Andreas-Peter Sitte
Chief Editor Mining Report Glückauf, Essen

ISSUE 02/2020

Long-Term Management of Mine Water Operations in the German Coalfields – an Interim Evaluation of the Findings Based on Operating Plans and Hydrological Permits

Fig. 1. Location of mine water pumping stations in the Ruhr area according to the new management plan. // Bild 1. Wasserhaltungen im Ruhrgebiet nach Umsetzung des Konzepts. Source/Quelle: RAG

The cessation of coal mining in North Rhine-Westphalia on 31st December 2018 marked the start of a period of long-term aftercare measures. The end of coal winning also meant that the original purpose of the mine dewatering operations, which was to make it possible to extract the resources in the first place by collecting the mine water and pumping it to the surface, no longer applied. This raises the question of whether and to what extent the dewatering measures should be continued, both for safety reasons and in the interest of environmental protection. It was with this in mind that the RAG Aktiengesellschaft, Essen/Germany, submitted its Mine Water Management Plan in 2014. This concept is now being implemented step by step – subject to the granting …

Authors: AdM Dipl.-Ing. Philipp Hensel (BVR), AdB Dipl.-Ing. Jürgen Kugel (BD), AdB Dipl.-Ing. Tassilo Terwelp (BD), AdB Dipl.-Ing. Jörg Tuschmann (BD), Abteilung 6, Bezirksregierung Arnsberg, Dortmund/Germany

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The Casing Pipe Method of Converting Mine Water Pumping Stations to Well-Type Operation Based on the Example of Carolinenglück 3 Shaft

Fig. 14. Carolinenglück 3 shaft after restoration. // Bild 14. Schacht Carolinenglück 3 nach Abschluss der Arbeiten. Source/Quelle: RAG

The northwards migration of the coal mining industry created a well-developed network of underground roadways and this allowed interconnected collieries to be organised as combined water drainage systems. This resulted in a centralisation of the water pumping operations. The mine water is currently pumped to the surface at a total of 13 pumping stations – RAG Aktiengesellschaft, Essen/Germany, has long-term plans in place to reduce this to six. In order to achieve this target RAG is now engaged in a revision of the entire water management system. Instead of the conventional method of underground pump …

Authors: Patrick Malejka, M.Sc, M.Eng., GEOtechnic – Ingenieurgesellschaft für Geotechnologie und Altbergbau, Bochum, Dipl.-Ing.(FH) Benjamin Röhl, RAG Aktiengesellschaft, Essen/Germany

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Explosion-Proof Casing-Pipe Obturator with Flap Valve Mechanism

Fig. 5. Flap valve mechanism. // Bild 5. Klappenmechanismus. // Photo/Foto: RAG

Optimising the mine de-watering arrangements involves converting the centralised drainage systems to water wells. In order to retain access to the mine water a series of casing pipes has to be cemented section by section into the filling column. These pipes can then be used at some future date to accommodate a number of submersible pumps. In view of the fact that gases can be released both from the abandoned mine workings, which are no longer being ventilated, and from the coal-bearing rock beds, there is a real risk of an explosive gas mixture being developed as the casing pipes are being installed …

Authors: Dipl.-Ing. (FH) Benjamin Röhl, und Dipl.-Ing. Dieter Hardes, RAG Aktiengesellschaft, EssenGermany

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Development of a Concreting System Based on the Climbing Formwork Concept for the Partial Filling of the Friedlicher Nachbar Shaft

Fig. 13. Concreting test (left: planned scenario; right: reality). // Bild 13. Betonierversuch (links: Planung; rechts: Realität). Source/Quelle: RAG

The Friedlicher Nachbar shaft in Bochum is one of the 13 central water pumping stations operated by RAG Aktiengesellschaft, Essen/Germany. One of the unusual features of this installation is that the operation to convert to a well-type system has to be carried out without switching off the pumps in the auxiliary ventilation shaft as any such shutdown would result in an increase in the mine water levels. This would lead to a transfer of water into the adjoining water management zones, something that must be avoided at all costs.

Because of ongoing pumping operations the conventional method of partial backfilling using the casing pipe method could be used. What is more, the significant lack of vertical alignment in the shaft …

Authors: Dipl.-Ing. Carsten Linka, ZPP Ingenieure AG, Bochum, Dipl.-Ing. Dieter Hardes, RAG Aktiengesellschaft, Essen/Germany

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Long-term Impact of Coal Mining on Surface Movement: Residual Subsidence versus Uplift

It is well known that longwall mining leads to a significant amount of surface subsidence. This is driven by a mechanical stress-deformation process that is initiated when the roof collapses in the mined-out area. Since entire coal basins recently have been closed in Europe, the focus has moved more to the long-term impact of mining. In various European coal basins, it has been observed that, after the mines were closed, there was a period of further residual subsidence, followed by upwards movement or uplift, which is linked to the flooding of the underground work areas. Based on data obtained by remote sensing techniques, this paper shows …

Author: Prof. Dr. André Vervoort, Research Unit Mining, KU Leuven, Leuven/Belgium

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New Prospects

Fig. 1. The area of the former West colliery in June 2019. // Bild 1. Die Fläche des ehemaligen Bergwerks West im Juni 2019. Photo/Foto: RAG Montan Immobilien/Thomas Stachelhaus

The landscaping of the State Garden Show 2020 in Kamp-Lintfort and the concomitant on-time clean-up and preparation of the area for future uses that are required are some of the special challenges facing RAG Montan Immobilien GmbH, Essen/Germany, which has been sustainably revitalising closed mining sites for more than 40 years. The park area of the State Garden Show on the former mining site of West colliery, which is in close proximity to the city’s centre, will be turned in future into the “Central Park” of Kamp-Lintfort.

Author: Stephan Conrad, RAG Montan Immobilien GmbH, Essen/Germany

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Research Areas in Post-Mining

Fig. 2. Examples for risk fields in Post-Mining. // Bild 2. Beispiele für Risikofelder im Nachbergbau. Photos/Fotos: 1. ©THGA; 2. ©RAG; 3. ©RAG; 4. ©THGA; 5. JERS data ©JAXA, SAR and InSAR, Verarbeitung durch die Gamma Remote Sensing AG, 1998; 6. ©RAG MI/Thomas Stachelhaus

The Research Institute for Post-Mining (FZN) at TH Georg Agricola University (THGA) in Bochum/Germany, has developed an integrated approach to meet the challenges of the post-mining era. Therefore, post-mining covers four research areas: Perpetual tasks and minewater management; Geomonitoring in post-mining; Material science for the preservation of industrial heritage; Reactivation and transition.

The institute is trying to fulfill central requirements of the UN to deal responsibly and sustainably with the resources of our planet. It plans to be a part of a national and international network in the interest of all social groups and the environment.

Author: Prof. Dr. Jürgen Kretschmann, Technische Hochschule Georg Agricola (THGA), Bochum/Germany

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New National Raw Materials Strategy: No Sustainability without Inclusion of Post-Mining

Fig. 1. BMWi information on the updating of the national raw materials strategy (4). // Bild 1. BMWi-Mitteilung zur Fortschreibung nationale Rohstoffstrategie (4).

The goal of the German government’s new national raw materials strategy is to confront current and foreseeable future challenges in securing raw materials for the German economy and in particular for the German industry from 2020 onwards. Issues of sustainability will be given greater priority than in the first raw materials strategy from 2010, and for the first time aspects relating to post-mining will also be addressed. However, post-mining needs to be given much greater weight if the requirement for sustainability in the raw materials strategy is to be satisfied. Thus, Germany can set an example internationally and offer perspectives by referring to national practices and projects for a sustainable management of post-mining effects and in particular the consequences from phasing-out coal mining. It can also contribute to improving acceptance of the raw materials policy on a national level.

Author: Dr. Kai van de Loo, Gesamtverband Steinkohle e. V. (GVSt), Essen, und Technische Hochschule Georg Agricola (THGA), Bochum

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Hard Coal 2019

The year 2019, just as the previous years 2017 and 2018, was a very poor one for hard coal in Germany. Electric power generation using hard coal was down by 31 % in 2019. Over the three years 2017, 2018 and 2019, cumulative power generation from hard coal fell by 49 % in comparison with 2016, i. e. by half. So the de facto exit from coal has been going on for a long time. If it were only a matter of reducing CO2, there would have been no need to make any decisions to phase out the generation of electricity from hard coal.

Nevertheless, hard coal-fired power plants make an important contribution to supporting the expansion of renewable energy sources and to stabilising the electricity system. To prove this scientifically, the Verein der Kohlenimporteure e. V. (VDKi), Berlin/Germany, commissioned Deloitte Finance last year to conduct a study on the flexibility of hard coal-fired power plants. The objective of the study was  …

Author: Prof. Dr. rer. pol. Franz-Josef Wodopia, Geschäftsführer, Verein der Kohlenimporteure e. V. (VDKi), Berlin

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