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

Abstract

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, SiO 2 and Al 2 O 3 but nucleating agents, such as TiO 2 , P 2 O 5 , and Fe 2 O 3 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 (MgSiO 3), or perhaps a pyroxenic phase which incorporates Ca, Mg and Al in its composition, and åkermanite (Ca 2 MgSi 2 O 7). The microstructure contained both fibre-like and dendritic crystals. The mechanical properties were acceptable for applications such as tiles for the building industry.

Nucleation and crystal growth of glasses produced by a generic plasma arc-process

“…As expected, a linear relationship was obtained. The value of E act determined from the slope of this line was 291 kJ/mol, which is lower than the value reported for glasses obtained from urban incineration ashes (379 kJ/mol) in which surface crystallisation also plays a major role in the glass devitrification 21 . This result suggests that PG glass would be easier to crystallise than urban incineration glass perhaps owing to its chemical composition with a great content in Fe 2 O 3 and TiO 2 , which are well established as nucleating agents for crystallisation 11 .…”

“…Glass-ceramics prepared by controlled devitrification of different inorganic wastes such as coal fly ashes, hydrometallurgical wastes or fly ashes from domiciliary solid waste incineration have been widely investigated [16][17][18][19][20][21][22][23][24][25] . However, to our knowledge, the processing of glass-ceramics by crystallisation of wastes from hospital fly ashes treated by Arc Plasma Technology (APT) has not been explored.…”

El proceso de vitrificación/cristalización controlada aplicado al reciclado de residuos industriales inorgánicos

“…DTA scans for powder and bulk samples from TIR65 glass show that surface crystallisation plays a major role in the crystallisation process (13). Figure 5 shows the nucleation curve for TIR65 glass.…”

“…The reduction in the effective nucleus térmico. Ensayos de ATD realizados sobre muestras en polvo y en vidrio masivo determinaron que el proceso de cristalización de este vidrio se desarrollará a través de un mecanismo de cristalización en la superficie y en el volumen del vidrio, siendo la cristalización superficial predominante (13).…”

“…A 950°C junto a éstas cristaliza una nueva fase de akermanita y a partir de 1000°C no hay variaciones importantes en la intensidad relativa de cada una de las fases (13).…”