Synthesis of α-cordierite based glass-ceramic from Bayan Obo tailing and fly ash through volume crystallization

Abstract

The α-cordierite glass-ceramics samples were synthesized from Bayan Obo mine tailing and fly ash through volume crystallization as a result of using (NH4) H2PO4 and MgF2 as the nucleating and glass network relaxing agents, respectively. The application of some natural impurities within above wastes, i.e., CaO, Na2O, and K2O, as the flux to lower the viscosity of the base glass, also contributed to this successful synthesis. The density, bending strength, Vickers hardness, dielectric constant and loss within the 1-10 MHz testing frequency range, and the average coefficient of thermal expansion of the glass-ceramic were characterized at 2.56 g cm−3, 113.5 ± 15.87 MPa, 7.04 ± 0.26 GPa, ∼7.3, ∼10−2 and 1.86 × 10−6 °C−1 respectively. These properties make this solid waste-derived material a lucrative candidate for replacing the industrial cordierite in metallurgy and construction. The results of this study may serve as a useful example of the re-utilization of solid wastes similar to Bayan Obo tailing with high added value.