DIETER: ‘Digitisation of mining structures through the combination of innovative sensor technology, artificial intelligence and process-based modelling’ is dedicated to the development and implementation of advanced technologies in flooded mining structures.
Commenced in 1858, the Neuhoffnungsstollen mine in Bad Ems was briefly the most important mine in Ems until 1882, when underground mining operations were prohibited due to damage to the adjacent thermal springs. Over the following years, mining operations for ores such as lead and silver were repeatedly resumed with official permits. The tunnel is over 350 metres long, has 15 underground levels and a shaft that is almost 900 metres deep. Groundwater flooded the mine after the end of the Second World War due to failed pumps.
According to Jan Sonntag, research assistant at the Faculty of Communication and Environment, who is supervising the DIETER project, the Neuhoffnungsstollen offers the perfect setting for research purposes: ” Since coal was never won in this mine, there is no exposure to fine dust and the equipment used does not need to be explosion-proof. Despite flooding, the shaft is fully accessible with a probe. Air circulation is adequate and the structural stability is also good.”
Plans for the DIETER project, which has been running since January 2024 and will continue until December 2026, provide for more detailed research into the Neuhoffnungsstollen tunnel. To this end, the IoT Lab at HSRW, represented by Prof. Dr.-Ing. Rolf Becker, Henrik Schoofs and Jan Sonntag, is installing extensive sensor and network technology. The goal, according to the Ruhr University Bochum, which is coordinating the project, is ‘to create an online tool that enables the monitoring and analysis of water quantity, water quality and geothermal potential, thereby providing local authorities with cost-effective and accessible tools.’
The information technology must be functioning
Each of the four partners in the DIETER project – Ruhr University Bochum (RUB), University of Stuttgart, HSRW and
EXWE GmbH – is responsible for one work package. HSRW’s IoT Lab responsibilities can be broken down into three smaller tasks:
- Provision of a general infrastructure for internal and external communication
- Installation of the sensor technology
- Providing data availability for partners in the cloud
But first, a brief definition of the Internet of Things: IoT, short for Internet of Things, refers to the networking of “smart” devices, such as sensors that can transmit, receive and process data. This isn’t just for research and industrial purposes: there would be no smart homes without the IoT.
The installation of the internet infrastructure by the HSRW IoT Lab in May 2024 was the first milestone in the project. ‘There was no need to lay cables,’ recalls Jan Sonntag. ‘We rely on wireless communication via radio technology. The sensors communicate with the main hub at shaft 3 via LoRaWAN, short for Long Range Wide Area Network. Another data hub is located at the entrance. This allows small amounts of data to be sent over longer distances.’
Numerous challenges had to be overcome. ‘The Neuhoffnungsstollen is a difficult environment and we had no previous experience of this kind,’ says Jan Sonntag. ‘Radio technology behaves differently inside the tunnel than outside. The high humidity of 90 per cent makes some sensors unsuitable, and the iron hydroxide, i.e. rust particles in the water, requires regular cleaning of the probes.’ On average, Jan Sonntag is on site every one and a half to two months.
The various types of sensors installed in the Neuhoffnungsstollen tunnel collect data on temperature, air pressure, humidity and CO2 every 20 to 30 minutes. The CO2 sensor technology is currently the subject of a bachelor’s thesis in collaboration with the Faculty of Technology and Bionics. Water parameters such as electrical conductivity, water level and temperature are collected in shaft 3. And in Shaft 2, the water level is recorded to determine a likely connection to Shaft 3. More and more sensors are being installed by the team, because what is currently being tested ‘above ground’ should also work underground: a level probe is to record a complete water column from the almost 900-metre-deep shaft every one to two hours in order to detect changes in its composition.
The IT service provider and project partner EXWE GmbH from Dortmund is to provide a data dashboard at the end of the project that will supply all relevant information about the local mine structure in real time. In addition, the sensor data generated will be made freely available to other researchers. RUB is using the data collected by the HSRW’s IoT Lab to develop a hardware and software-based monitoring tool (soft sensors). More information about the DIETER project and a blog with updates can be found on the website https://bergwerk-digital.de/ .
Glossary
Adit = horizontal connections between the earth’s surface and the deposit
Mine = mine developed from former open-cast mining
Shaft = Vertical pit construction for accessing a deposit
Level = Comparable to floors in a house
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