Slag or ash is residual material from combustion processes in power stations or from waste incineration plants. Slags from WIPs are particularly significant for the protection of the environment.


Waste incineration produces about 250 - 350 kg of slag from every ton of waste. This waste is - like the waste itself - of an extremely different composition with respect to the content of mineral substances, iron scrap, water and heavy metals.

Prior to the further use of the WIP grate ash must be treated and stored such that it complies with the quality requirements of the intended later utilization.


In most cases the slag is conveyed from the WIP to the treatment plant via conveying equipment. There, it is pre-stored for an integration of air CO2 for at least one day. Then, the slag is sieved and crushed . Iron scrap and non-ferrous metals such as aluminium, copper and brass are separated from the slag and will be re-used in metallurgical facilities as raw material. Unburnt rests will be processed and removed in a classifier.

Since physical and chemical processes are running at the same time in the slag, it is important according to the technical regulations that they also be considered and the slag be stored after processing over a certain period of time. Only if the specified requirements are complied with, this product can be used as a secondary product and/or construction material in road constructions Time and technology will work for the quality of the slag.