Glass-ceramic produced from a municipal waste incinerator fly ash with high Cl content

This study is concerned with recycling waste materials, focusing on the development of a glass-ceramic from Korean incinerator fly ash with a high Cl content, and the evaluation of its physical properties. In the process, water washing as a pre-treatment before melting the fly ash was used to remove the large amount of Cl in the ash, and to reduce the melting temperature of the fly ash. As a result, glass was obtained at 100 degrees lower than the non-water-washed fly ash. Also, internal crystallization occurred under a single stage heat treatment (at 850–950 °C for 20–240 min) without adding other materials to the ash. It was found that the glass-ceramic was composed of three crystals, gehlenite, augite, and calcium aluminium oxide. Hardness of 8.3 GPa, fracture toughness of 1.7 MPam1/2, elastic constant of 145 GPa, and thermal expansion coefficient of 10.5–11.5×10−6/K were found in the glass-ceramic, which were high values compared with others reported. Thus, the present process suggests that such glass-ceramic produced from an incinerator ash could be applicable for structural materials in terms of economic and environmental points.