Fast sinter-crystallization of a glass from waste materials

A glass belonging to the CaO–Al2O3–SiO2 system and corresponding to the melting of a mixture of industrial inorganic waste (feldspar mining residues, lime from fume abatement systems of the glass industry and recycled soda–lime glass) has been successfully transformed into dense and strong sintered glass–ceramics, even for very short holding times (30 min at 960 °C) and a very rapid heating, consisting of direct insertion of pressed fine glass powders in furnace (‘fast sinter-crystallization’). The addition of kaolin clay, conceived as binder for pressed glass powders, proved to positively influence the phase balance, the homogeneity and the degree of crystallization of fast sintered glass–ceramics, thus justifying the achievement of remarkable mechanical properties (bending strength exceeding 100 MPa, micro-hardness exceeding 7 GPa).