The Schallacker slag heap in Dortmund is an old slag heap that was created as part of the industrial heritage of Phoenix West. It originally served as a landfill for the slag from the blast furnaces of the Phoenix steelworks. Together with the neighboring Hympendahl slag heap, it forms a characteristic feature of the industrial landscape in Dortmund-Hörde. In order to transport the slag, a slag railway with a viaduct was built between the two slag heaps, although this is no longer completely intact today. The slag heap landscape itself consists of heaped slag material that has partially changed over time through renaturation and greening.
The Schallacker slag heap is located near the Phoenix Lake and the former steelworks site, which is now used as a technology park and local recreation area. It is part of the industrial culture in the Ruhr area and offers insights into the change from an industrial area to a green and recreational area.