Refuse derived fuel

The use of refuse derived fuel (RDF) is part and parcel of today's regulated waste disposal. Triggered by judicial specifications that ban the landfilling of untreated waste, or at least hamper it, this fuel is continually gaining in importance in light of climate protection and rising energy costs.

Using a selective treatment process, fractions high in calorific value are separated off from commercial and industrial waste, creating a marketable product. Depending on calorific value, composition and particle size, this fuel is used in industrial fluidised bed firings, in cement kilns and in RDF power plants.

Pre-shredding must bring the input material down to a homogeneous particle size and prevent problematic overlengths for subsequent processing stages. A high level of resistance to contraries is just as important.

The single-shaft shredder Terminator addresses these requirements in a perfect way. The highest degree of material opening is achieved using the XF-unit. If coarser particles are required the cutting gap can be opened or even replaced by another shredding unit for coarser fractions (XF<F<UF<U).

The material flow is diverted into four fractions by the ballistic separator: Flat,

rolling and as two screen fractions, with holes of 0-30 and 30-80 mm for example. Usually the smaller screen fraction is biologically stabilized in a mechanical biological-treatment plant. The coarse screen fraction has a calorific value of 12-18 MJ/kg and enables a saving of fossile fuels when used in fluidized bed incineration plants.

Potential recyclables, or fractions high in calorific value, can be separated off from the rolling fraction for postshredding using inductive and optical sorting systems. After Iron/Non-iron separation the remaining fraction is again fed to the shredder.

The flat, high calorific fraction (calorific value 18-25 MJ/kg) is made up primarily of foil and packaging fractions and is the input material for the last processing step - post-shredding with the Rasor. Depending on the inbuilt screen basket the machine generates both an injectable fraction (< 35 mm) and a particle size (60-100 mm) known as fluidized bed fraction.