At the Hambach opencast mine the composition of the overburden changed with the advance of mining activity into new grounds: on some benches the amount of unstable soils (difficult to transport and deposit) increased, on other benches hard concretions (difficult to excavate) appeared and at present form extensive clay-ironstone horizons. Mining, transport and deposit of these two kinds of materials are the current challenges of the Hambach opencast mine. The management of unstable soils has become very complex from a planning and an operational point of view. Furthermore, the large amounts of unstable soils that need to be deposited on this dump may not affect its stability. Finally, clay layers in which hard siderite concretions occur decrease the productivity of bucket wheel excavators and cause damage to these excavators and the downstream conveyor belts. The results of the research and development at Hambach focussing on these issues will be highlighted.
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