Glass-ceramics for construction materials synthesized from municipal incinerator residue

Abstract

Increasing accumulation of municipal incinerator residue (hereafter called MIR) have been becoming a serious social problem in view of environmental loading, and its reuse or recycling as starting materials of ceramics products is urgently required. Since the glass-ceramics of the CaO-Al2O 3-SiO2 system have been promising as construction materials, we have investigated the preparation technique of this glass-ceramics from MIR by the bulk crystallization method. The structures of glass-ceramics were investigated by means of video microscope (VMS), scanning electron microscope (SEM), powder X-ray diffraction (XRD), and so on. Batches were prepared by mixing the various weight ratios in order to get the composition; MIR:SiO2:CaCO3:FeS:Na2SO4= 100:10-30:10-30:3-5:0-5. Glass samples were produced by melting the batches at 1450°C. From those batch compositions, the homogenous glasses were produced. They were reheated at 800°C for 1 h to induce nucleation in the glasses. Further, the glasses were reheated at 1100°C for 2 h, to make them transform into glass-ceramics. The results of VMS photographs, SEM photographs and powder XRD patterns of the obtained glass-ceramics showed the homogeneous precipitations of the prismatic crystals (about 0.5 × 2 μm) of Anorthite (CaO·Al2O3·-2SiO2) and Wollastonite (CaO·SiO2) by the bulk crystallization, accompanied by a small quantity of Gehlenite (2CaO·Al2O 3 SiO2) and/or Nepheline (NaO2·Al 2O3·2SiO2).