Coal fly ash and steel slag valorisation throughout a vitrification process

Abstract

The aim of this research was to evaluate the feasibility of using the vitrification process as an alternative solution to the disposal of a coal fly ash and metallurgical slags in landfills. The starting wastes were characterised in terms of chemical, granulometric, mineralogical, and microstructural analysis. A selected batch composition composed by 58.5% fly ash, 31.5% metallurgical slag and 10.0 Na2O% (wt%) was melted at 1450 °C and poured to obtain monolithic glass samples. The environmental behaviour of the starting wastes and the resulting glass was evaluated by standard leaching tests, which shows that vitrification leads to a stabilisation process in which the inorganic components of the wastes are immobilised throughout their incorporation into the glass structure. Moreover, vitrification transforms those hazardous wastes into a new non-hazardous glass. A preliminary study shows that the new glass is suitable for developing glass–ceramic tiles appropriate for floor pavement and wall covering.