Up to 400,000 cubic metres of lignite and overburden are mined by the huge lignite excavator – every day. 

To ensure high-quality extraction, precise soil maps of the deposit are indispensable. They provide insight into the exact location of the various overburden layers and lignite seams. With the new method, RWE is improving the accuracy of the soil maps prior to actual extraction by bucket wheel excavator. 

A look into the soil 

Depending on the location, up to 300 metres of overlying strata consisting of topsoil, clay, gravel and sand have to be removed before lignite mining can commence. Dewatering drillings give information about the properties and thickness of the overburden. RWE's engineers gain further insights by looking into the soil. One method that RWE is currently developing uses a georadar or geoelectrics. 

The device sends its sensor waves from the bucket wheel into the material to be mined, where they are reflected by the soil in different ways, and a soil pattern becomes visible. It is already clear, however, that use of more precise soil analyses will in the near future be able to increase the quality and quantity of the excavated material and further improve the overall economic efficiency of lignite mining.