Recovery of aluminum, magnetic ferrous metals and glass through enhanced industrial-scale treatment of different MSWI bottom ashes

Abstract

To foster a circular economy, the EU will increase recycling targets for packaging materials, including aluminum, ferrous metals and glass. Recovery of packaging metals from incineration bottom ashes (IBA) from municipal solid waste incineration can contribute to achieving these targets. Nevertheless, recoverable metal and glass amounts from IBA, and in particular IBA from fluidized bed combustion, are rarely investigated. Therefore, this work aims to assess the recoverable amounts of aluminum, magnetic ferrous metals and glass > 4 mm from different types of IBA through enhanced treatment. In an industrial-scale treatment experiment with one batch of IBA from grate and one from fluidized bed combustion, masses and compositions of all output flows of the treatment plant were determined. Material flow analysis was used to study the distribution of the investigated materials during the treatment process. Results show that glass separation was not feasible for the grate IBA, which only contained 7 % glass > 4 mm. The fluidized bed IBA contained 42 % glass > 4 mm, of which 72 % were recovered. More aluminum and magnetic ferrous metals > 4 mm were found in the fluidized bed IBA, also exhibiting less mineral agglomeration compared to those from grate IBA. The study demonstrated that enhanced industrial IBA treatment can recover > 95 % of aluminum and magnetic ferrous metals > 4 mm, not observing significant differences between these metals. Thus, a cutting-edge IBA treatment can enable the recovery of recyclable material from IBA and therefore contribute to a circular economy. Furthermore, fluidized bed IBA shows advantages regarding its recycling options compared to grate IBA.

Keywords: Fluidized bed combustion; Glass recycling; Grate incineration; Incineration bottom ash; Metal recycling; Municipal solid waste incineration.