Metal recovery to allow improved beneficial reuse of energy-from-waste residues in civil engineering
Started: October 2017
Supervisor: Professor Chris Cheeseman
Industry Partner: WtERT
Description of Research
The research objective is to find solutions to reuse energy-from-waste residues in order to promote a more circular economy.
Energy-from-waste (EfW) systems treat municipal solid waste (MSW) through incineration. EfW diverts MSW from landfill whilst also generating energy. The CO2 generated through EfW is 25 times less than the methane produced by landfill, and the volume of MSW is reduced by 90%. The remaining residues are incinerator bottom ash (IBA), fly ash (FA) and air-pollution-control (APC) residues. IBA is composed of the inert, non-combustible materials of the MSW. The composition of IBA varies due to the heterogeneity of the MSW feedstock, but generally 80-85% of IBA is mineral fraction, 10-12% is metals, 2-5% is non-ferrous metals. Metals such as steel, aluminium, copper and zinc are commonly recycled from IBA, they are separated from the rest of the ash through magnetic and eddy current separation processes. The recovery rate of metals from IBA is about 80%. The inert fraction can be recycled and used in road construction or as aggregate in concrete. Rare earth metals, precious metals and critical raw materials are present within the fine fraction of the IBA.