Zircon Decomposition in Glass Melting Furnaces: Experimental and Thermodynamic Approaches

ABSTRACT The decomposition of zircon (ZrSiO ₄ ) refractories by fiberglass compositions at high temperatures (>1300°C) was investigated using the static cup test and two thermodynamic approaches, including an empirical method and calculations performed in FactSage. The glass‐refractory interface was investigated using X‐ray diffraction (XRD) in conjunction with scanning electron microscopy (SEM). The tests revealed that, in general, high [CaO]+[Al ₂ O ₃ ] contents result in a decrease in the zircon breakdown temperature below its theoretical chemical decomposition value, promoting the formation of zirconia (ZrO ₂ ). The empirical thermodynamic model based on linear regression is found to underestimate the breakdown temperatures with errors up to 30% when initial data for aluminosilicate glasses was used. This error is mainly attributed to the absence of TiO ₂ in the raw data used. After the model is updated, the linear regression model shows a significant enhancement, achieving errors below 1%. Likewise, thermodynamic calculations in FactSage show an acceptable agreement with experimental results for most of the glass compositions. Additionally, thermodynamic analysis suggests that acidobasicity plays a key role in the effect of the distinct glass compositions on the zircon decomposition.