Slag or ash are residues from incineration processes either from the power station area (coalfired or lignite-fired power plants) or e.g. from furnaces and/or waste incineration plants. The slag from incineration are especially significant for the protection of the environment. When waste is incinerated, approximately 250 to 350 kg are generated from each ton of waste.

They have (as the waste itself ) a very different composition as far as the content of mineral material, iron scrap, water and heavy metals are concerned. Therefore, the slag must be treated prior to use as building material in road and street construction. Sutco RecyclingTechnik has erected several plants which satisfy the requirements for this use.