Thermal Treatment as a Chance for Material Recovery

Abstract

The recovery of materials in the course of thermal waste treatment may sound contradictory at first glance because thermal treatment is supposed to destroy materials. However, this is only the case for organic materials. But waste consists of more: Metals and minerals are part of the trash, and there are options to get them back afterward or better by thermal treatment.

This chapter addresses the possibilities for recovering resources for material applications by thermal waste treatment. Two thermal routes are considered: Waste-to-energy (WtE) plants and pyrolytic disintegration approaches.

WtE enables the recovery of iron, nonferrous metals, and also minerals from bottom ash. Another opportunity for material recovery is flue gas utilization. The recovery and material utilization of HCl and sulfur (in the form of gypsum) has been industrially practiced for decades. In the last few years, the first approaches to recover metals from the filter dust were also industrially implemented.

Pyrolytic processes offer the chance to recover valuables from composite material parts, like carbon fiber-reinforced plastics (CFRP), or from metal-enriched fractions of other waste treatment processes like shredder residues. The containing plastics can be volatilized at high temperatures and the emerging pyrolysis gases can be utilized to supply the thermal energy for the process. The absence of oxygen and relatively low temperatures prevents the valuables in the composite matrix from damage.