Development of a new glass–ceramic by means of controlled vitrification and crystallisation of inorganic wastes from urban incineration

This paper reports the results of a study of the feasibility of recycling the solid residues from domiciliary waste incineration by producing a glass-ceramic. The major components of the raw material (TIRME F+L), which was from a Spanish domiciliary incinerator, were CaO, SiO2 and Al2O3 but nucleating agents, such as TiO2, P2O5, and Fe2O3 were also present in reasonable amounts. It was found that a relatively stable glass with suitable viscosity could be obtained by mixing 65 wt% TIRME F+L with 35 wt% glass cullet. The heat treatment required to crystallise the glass produced from this mixture, designated TIR65, was nucleation at 560°C for 35 min followed by crystal growth at 100°C for 120 min. The resulting glass-ceramic contained a number of crystalline phases, the most stable being clinoenstatite (MgSiO3), or perhaps a pyroxenic phase which incorporates Ca, Mg and Al in its composition, and åkermanite (Ca2MgSi2O7). The microstructure contained both fibre-like and dendritic crystals. The mechanical properties were acceptable for applications such as tiles for the building industry.