Waste-to-energy and biomass
Incinerator bottom ash
Also known as IBA, bottom ash (WtE).
Incinerator bottom ash (IBA) is the non-combustible residue discharged from the bottom of a grate-fired WtE boiler. IBA accounts for ~20–25% of the original waste mass and consists of glass, ceramics, metals, fused inorganics and small quantities of unburned organics.
Recovery and reuse
IBA is increasingly processed rather than landfilled:
- Metal recovery — magnetic and eddy-current separation extracts ferrous and non-ferrous metals (typically 8–12% of IBA mass)
- Aggregate use — the processed mineral fraction is used as secondary aggregate in road sub-base, concrete blocks and other applications
- Landfill — residual material that fails leaching tests goes to landfill
Distinguish IBA from APC residue (air-pollution-control residue), which is the much smaller but more hazardous fraction captured from the flue gas downstream of the boiler.
Sonic-horn relevance
IBA itself is not a sonic-horn target — it is wet, coarse, and gravity-discharged. The associated bottom-ash conveyors and downstream metal-recovery processing hoppers occasionally benefit from acoustic flow aids.
Related terms
Related terms
- Waste-to-energyWtE plants burn municipal solid waste, RDF, SRF and biomass to generate steam and electricity. Sticky chloride-rich ash defeats conventional cleaning; sonic horns are the dominant fit.
- Grate-fired boiler and mass-burn incineratorGrate-fired (mass-burn) WtE boilers burn MSW on a moving grate without fuel pre-processing. The dominant design for municipal waste incineration.
- Air-pollution-control residueAPC residue is the fine fly-ash plus reagent salts captured by the WtE flue-gas treatment train. Classified as hazardous waste; requires specialised disposal.