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Underground recovery

Waste disposal & use

Underground recovery is a sensible method of utilizing your waste. The backfill materials produced from it are dumped 500 to 800 meters below the earth's surface in the salt rock and disposed of safely for the long term.


Typical waste for underground recovery:

  • Residues from flue gas cleaning of waste incineration plants
  • Sinter dust from the metal industry
  • Aluminum filter dusts
  • Contaminated soil and rubble
  • Saline waste
  • Sludge from chemical-physical treatment and electroplating sludge

We place your waste in the caverns that were once created during the extraction of potash and rock salt, where no more raw materials are mined. According to law, mine areas that no longer comply with today's safety standards must be backfilled (obligation to backfill under mining law).

Thanks to the location of the cavities between impermeable clay and salt layers, your waste will be safely stored over the long term. With five underground recovery facilities, K+S has the largest capacities in Europe, which will be sufficient for many decades to come.

In order to permanently secure an underground cavity, a filling material with certain physical properties is required, depending on its composition. Some types of waste bring with them the properties that are in demand. Otherwise, we achieve this by combining suitable components (conditioning). Our engineers have developed many special processes for conditioning and processing - and we continue to carry out research on an ongoing basis.

Types of backfill


Storing backfill

In the backfilling process, waste is packed in big bags and stacked in the mining chambers and the spaces between them filled with salt. The aim is a 100% connection to the surrounding rock. In order to achieve the necessary stability and compressive strength, some wastes have to be conditioned. Waste with a higher pollutant content can also be recycled in this way.


Slurry backfill

Pneumatically transportable waste is converted into slurries based on our own recipes, which harden at the place of destination. It is a science in itself to mix the individual substances in such a way that they flow through the kilometer-long, branched pipe system, harden at the right time and do not release any liquid later. The thick matter plant with its highly sophisticated technology was specially developed by K+S engineers.


Tipping backfill

In this process, your waste is packed into big bags or sacks in suitable mining chambers and then compacted as a backfill mixture.

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