Development of glass-ceramics from plasma treated air pollution control (APC) residues from waste incineration plants

Amutha Rania Devaraj, Imperial College London

The release of atmospheric pollutants from municipal solid waste incineration in modern energy from waste (EfW) plants is controlled by air pollution abatement systems that generate significant amounts of air pollution control (APC) residues. These are classified as hazardous waste, primarily because of their high alkalinity (pH>12), although they also contain volatile heavy metals, soluble salts and trace organics, including dioxins and furans. An integrated solution for APC residues using DC plasma technology is being investigated. Treatment at temperatures above 1400°C reduces the APC residue volume and produces a stable and non-hazardous inert glass that has potential to be beneficially reused.

APC residues from a major UK EfW plant have been combined with suitable fluxing agents and melted using DC plasma arc technology and cast to form a vitrified glass. The APC residue derived glass has been characterised in terms of composition and leaching and the potential for the glass to be converted into glass-ceramics with useful physical and mechanical properties has been assessed. Scanning electron microscopy (SEM) combined with energy dispersive X-ray (EDS) analysis was used to determine the chemical composition of the vitrified glass. Leaching was evaluated using the EU compliance leaching test for granular waste (BS EN 12457-4). Crystallisation of the vitrified glass was studied using differential thermal analysis (DTA) for both the powdered and bulk glass. Heat treatments of the vitrified glass have been performed at a range of temperatures and the resulting crystalline phases have been analysed by X-ray diffraction and microstructural analysis completed using scanning electron microscopy. Mechanical properties assessed included bulk density, Young's modulus, Vickers hardness and flexural strength. The potential for using glass-ceramics derived from DC plasma treated APC residues in a range of applications is discussed.

 

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