Abstract

During lignite exploitation in the Rhenish lignite district, a low excavation of sediments (sands and clays) neighboring the lignite cannot be completely avoided. Thereby, the chemical and mineralogical compositions as well as the combustion residues are modified, if those contaminated lignite is used as steam coal, and it is possible that it shows other properties during combustion with regard to its propensity of developing undesired accumulations in boilers, such as sinter or slacks, in comparison to pure lignite. In the Rhenish lignite district, there are three opencast mining spots still in operation: Garzweiler mine, Hambach mine (Figure 1) and Inden mine. Although the mining spots are not far away from each other in spatial distance and the seams have similar ages, they vary significantly in their chemical composition because of their different environment during deposition and formation. Therefore, the adjacent sediments also vary with their chemical and mineralogical compounds within and between the mining spots.