Landfilling

Thermal use of smouldering mine dump fires

Uncontrolled smouldering fires on coal mine dumps have a negative impact on the environment and climate due to the gas emissions. Taking a long term view, monitoring and securing heat sectors on mine dumps is also very costly. As part of this project, the partners are investigating the possibilities for thermal and energy use of mine dump fires.

Summary

In old coal mine dumps, the ingress of air can cause smouldering fires. Because of the residual coal content, these smouldering fires represent a significant safety risk. Emissions also contribute to the greenhouse effect. 

In this project, the partners are investigating the thermal potential of smouldering mine dump fires in terms of possible use of the heat sectors for generating heat and energy. Heat output was tested with three geothermal probes. Sand was used as filler material for the borehole, but it has low heat conductivity. 

The yields from use of the heat covered the costs of securing the mine dump. In addition, using the heat enabled fossil fuels to be saved. Thermal use of smouldering mine dump fires would therefore not only be technically feasible, it also makes economic and ecological sense. 

Results:

  • To counter smouldering fires, modern mine dumps are compressed after dumping to minimise the risk of spontaneous ignition due to oxidation.
  • The fall in the inlet temperature in smouldering mine dump fires can be countered by increasing the number of probes or using heat pumps.
  • Due to low efficiencies of 10%, geothermal power generation is not economical compared to thermal use.
  • Using the geothermal energy as heating energy is only effective at temperatures above 70°C.
  • The measurements showed a significant temperature increase below a bore depth of 10 m to 100°C at a depth of 25 m.
  • The highest underground temperature measured was 425°C.
  • The three probes enabled a total output of 8 kW to be achieved.
  • The waste heat discharged can only be effectively used for direct heating of a large building.
  • Peak loads were absorbed using a conventional gas burner or a heat pump.

Promotion

Promoting institutions

Federal Ministry of Education and Research (BMBF)

Promotional program

Klimazwei

More Project Informations

Project title:  Verbundvorhaben Klimaschutz: Thermische Nutzung von Haldenschwelbränden

Project number:  01LS05086

Project period:  2006 - 2011

Project region:  Germany (North Rhine-Westphalia)

Project contact:

Frau Dipl.-Ing. Klein

Herr Dipl.-Ing. Schwerdt

+49 (0) 208 8598-1173

Frau Dipl.-Ing. Kürten

This email address is being protected from spambots. You need JavaScript enabled to view it.

+49 (0) 241 - 80-25258

+49 (0) 241 - 80-22384

Herr Dr. Gaschnitz

+49 (0) 2365 – 9318-148

+49 (0) 02365 – 9318-425

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Source: German National Library of Science and Technology Hannover (TIB)