Grate fly ash and fluidized bed fly ash mixed with glass cullet additive respectively were melted in the electronic arc-furnace. The product, arc-melting slag, was further treated by crushing, pressing and heat treatment in order to make the glass-ceramics. The crystallization behaviors of the produced glass-ceramics were examined by differential thermal analysis (DTA), X-ray diffractometry (XRD) and scanning electron microscopy (SEM). Results show that main crystalline phase of the glass-ceramics from grate fly ash is wollastonite (CaSiO3) with small amount of diopside (Ca(Mg,Al)(Si,Al)2O6), and that from fluidized bed fly ash is diopside (Ca(Mg,Al)(Si,Al)2O6). It is found that the glass-ceramics sintered at 850 °C and 1 000 °C from grate fly ash and fluidized bed fly ash respectively have the optimal physical, mechanical and chemical characteristics. Glass-ceramics samples, produced from incinerator fly ash with desirable properties and the low leaching concentration of heavy metals, can be the substitute of nature materials such as marble, granite and porcelain tiles.
Production of glass-ceramics by sintering the molten slag obtained from electric arc furnace treatment of fly ash was investigated. The effect of washing pretreatment prior to melting the fly ash on the microstructure and properties of the glass-ceramics was examined. The results show that washing pretreatment of fly ash can decrease alkali metal chloride and increase network former in fly ash, which results in the increase of peak crystallization temperature of parent glass and strengthening of properties of bending strength and chemical stability of the glass-ceramics. The optimal heat treatment temperature for parent glass of washed fly ash is 1 173 K, at which the crystalline phase of glass-ceramics is composed of gelignite (Ca2Al2SiO7) and akermanite (Ca2MgSi2O7). Glass-ceramics produced at optimal heat treatment temperature are excellent in term of the physical and chemical properties and leaching characteristics, indicating attractive potential as substitute of nature materials.
