Glass-ceramics for construction materials synthesized from municipal incinerator residue

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-Al2O3-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 degrees C. From those batch compositions, the homogenous glasses were produced. They were reheated at 800 degrees C for 1h to induce nucleation in the glasses. Further, the glasses were reheated at 1100 degrees C for 2h, 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 x 2 mu m) of Anorthite (CaO center dot Al2O3 center dot 2SiO(2)) and Wollastonite (CaO center dot SiO2) by the bulk crystallization, accompanied by a small quantity of Gehlenite (2CaO center dot(Al2O3SiO2)-Si-center dot) and/or Nepheline (NaO2 center dot Al2O3 center dot 2SiO(2))