Conversion of microwave pyrolysed ASR's char using high temperature agents

Pyrolysis enables to recover metals and organic feedstock from waste conglomerates such as: automotive shredder residue (ASR). ASR as well as its pyrolysis solid products, is a morphologically and chemically varied mixture, containing mineral materials, including hazardous heavy metals. The aim of the work is to generate fundamental knowledge on the conversion of the organic residues of the solid products after ASR's microwave pyrolysis, treated at various temperatures and with two different types of gasifying agent: pure steam or 3% (v/v) of oxygen. The research is conducted using a lab-scale, plug-flow gasifier, with an integrated scale for analysing mass loss changes over time of experiment, serving as macro TG at 950, 850 and 760 °C. The reaction rate of char decomposition was investigated, based on carbon conversion during gasification and pyrolysis stage. It was found in both fractions that char conversion rate decreases with the rise of external gas temperature, regardless of the gasifying agent. No significant differences between the reaction rates undergoing with steam and oxygen for char decomposition has been observed. This abnormal char behaviour might have been caused by the inhibiting effects of ash, especially alkali metals on char activity or due to deformation of char structure during microwave heating.