The waste material is almost completely burned up by the time it reaches the end of the incineration grate.  The only end product of combustion that remains is slag, which falls into a water bath through openings in the grate, where it can cool off (wet slag remover).
 
The high combustion temperature ensures full inclusion of the ingredients formerly contained in the waste.

 
The slag contains glass, metal and ceramic residual material, molten together by the high temperatures.  Slag is a versatile end product. It has to however be prepared appropriately before reuse.
 
The first step involves washing out the easily soluble salts in a water bath. The material is then broken up, followed by removal of suspended matter.  The material is then aged for at least three months on an open-air trapezoidal heap. The metal fraction is stored separately and sent for recycling.
 

Treatment of slag is regulated by the specifications of the German Working Group of the Federal States on Waste Issues (LAGA) and is required to fulfil certain criteria. Material intended for recycling has to comply with various product characteristics required for quality assurance.
The material may only be used if this is the case. There are various different ways in which the product can be used in construction:

• Bearing layer under concrete, asphalt or paving
  
• Road embankment substructure
  
• Mineral surface cover for noise prevention barriers
  
• Integration in waste dump areas as equalising layer between waste and surface sealing

Using slag helps to conserve natural resources such as gravel and sand as well as reducing intensive landscape consumption. Being absolutely reaction-free, toxic leakage water or gases are no longer emitted.