Preparation of CaO–Al2O3–SiO2 glass ceramics from coal gangue

For the recycling and exploitation of coal industry wastes, CaO–Al2O3–SiO2 glass ceramics were prepared using up to 70 wt.% coal gangue as the main starting materials. The coal wastes were characterized, and the processing schedule, crystal phases, microstructure and properties of the glass ceramics were investigated. The prepared glass ceramics showed dense and homogeneous microstructure with crystal size of about 4 μm. Crystallization was observed at 1020 °C, producing crystalline gehlenite (Ca2Al2SiO7) as the major phase and nepheline (NaAlSiO4) as the minor phase. The prepared glass ceramics exhibited attractive physical, mechanical and corrosion resistance properties, showing large application potential for construction purposes.

► Up to 70% coal gangue was used as the staring material of glass ceramics. ► The prepared CaO–Al2O3–SiO2 glass ceramics has a crystal size of about 4 μm. ► The glass ceramics has crystalline gehlenite (Ca2Al2SiO7) as the major phase. ► The glass ceramics shows better properties than natural marbles and granites. ► The glass ceramics shows large application potential for construction purposes.