Preparation and properties of glass-ceramics from wastes (Kira) of silica sand and kaolin clay refining

• Published in: Journal of the European Ceramic Society 2004-07, Vol.24 (8), p.2367-2372
• Main Authors: TOYA, Tomohiro, KAMESHIMA, Yoshikazu, YASUMORI, Atsuo, OKADA, Kiyoshi
• Format: Article
• Language: English
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Chemical industry and chemicals; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Glass-based composites, vitroceramics; Glass-ceramics; Glasses; Materials science; Other industrial wastes. Sewage sludge; Other materials; Physics; Pollution; Specific materials; Wastes
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/s0955-2219(03)00628-9

Glass-ceramics were prepared from wastes generated from refining of silica sand and kaolin clay, called Kira. Several kinds of Kira were melted at 1300-1550NBDGC with additions of CaCO3 and quenched in air or water to obtain glasses. The quenched glasses were ground to < 48 mesh and used to prepare glass-ceramics. Crystallization of the parent glass occurred above 950NBDGC, producing wollastonite as a major crystalline phase which gradually transformed to pseudowollastonite above 1150NBDGC. The macroscopic appearance of the samples changed from transparent pale green glass to smooth-textured shiny white upon crystallization. The thermal expansion coefficient of the glass-ceramics was 5.2x10-6/DGC (30-380NBDGC). The four-point bending strengths of the as-fired glass-ceramics ranged from 76 to 86 MPa. Vickers microhardness was found to be 6.6-7.5 GPa. Since the chemical durability for acid and alkali was excellent in these glass-ceramics, they are considered to be candidates for applications such as building materials, ceramic tiles, etc.