Effect of nucleating agent on the crystallization of tailings glass ceramics prepared by one-time sintering

Abstract

Glass ceramics was made by the one-time sintering method using the main raw material of iron tailings. On the basis of quaternary system of CaO-MgO-Al₂O₃-SiO₂, using DTA, XRD and SEM, the effects of different nucleating agents and mixing amounts as well as heat treatment on the crystallization of tailings glass ceramics were studied. The experimental results show that, nucleating agent and heat treatment are two necessary conditions for one-time sintering preparation of tailings glass ceramics namely, only adding nucleating agent or experiencing heat treatment, the quaternary system can not crystallize. The composite nucleating agent consisting of Cr₂O₃ and TiO₂ can further lead to the crystallization of the CaO-MgO-Al₂O₃-SiO₂ quaternary system at the lower temperature, with the major phase of diopside. In the range of mass content, 0%–4%, crystal intensity and crystal content grow. But when mass content is more than 4%, the crystal size will become coarser and the crystal distribution will be less regular. Different heat treatment regimes do not change the composition of the crystalline major phase in the glass ceramics crystallization of CaO-MgO-Al₂O₃-SiO₂ system. In the range of 30–60 minutes, with the extension of nucleation and crystallization, crystallization degree enhanced, but if the holding time surpasses 60 minutes, the crystallization is worse.

Keywords

nucleating agent / one-time sintering / tailings / glass ceramics / crystallization

References

[1] Sun S., Miao J., Wang F. Study and Production Practice on the Comprehensive Utilization and Zero Emission of Ore Dressing Tailings[J]. Environmental Engineering, 2004, 22(5): 55-56.

[2] Liu J., Ou Y., Xu C., Qi H. Effect of Heat Ttreatment Method on Microstructure of Tailings Glass-ceramics[J]. Journal of Wuhan University of Technology-Materials Science Edition, 2008, 23(6): 883-888.

[3] Cheng J., Li H. Glass Ceramics[M], 2006 Beijing Chemical Industry Press

[4] Cheng T. W., Cheng Y. S. On Formation of CaO-Al₂O₃-SiO₂ Glass-ceramics by Vitrification of Incinerator Fly Ash [J]. Chemosphere, 2003, 51: 817-824.

[5] Liu J. Study on Nucleating Agent of Metal Tailings Glass-ceramic[J]. Journal of Northeastern University(Natural Science Edition), 1998, 19(15): 452-455.

[6] Liu Hao, Zhang Yongai, Yuan Jian. Research on Crystallization and Heat Treatment Process of MgO-Al₂O₃-SiO₂ Glass-ceramic[J], Glass. 2004 (2): 6–9

[7] Shi P., Wang Y., Zhang D. Effect of Crystallization Process on the Microstructure of Ion Tailings Glass-ceramic[J]. Journal of Northeastern University (Natural Science Edition), 2007, 28(5): 668-671.

[8] Holand W., Beall G. Glass-ceramic Technology[M], 2002 Westerville The American Ceramic Society