Ceramics-Silikáty 42 (1) 1-7 (1998)

THE SIGNIFICANCE OF THE REDOX STATE OF GLASS FOR THE BUBBLE BEHAVIOUR AT NON-ISOTHERMAL CONDITIONS 

L. Němec, M. Raková 

The model of calculation of the simultaneous oxidation-reduction equilibria in non-isothermal flowing glass melt has been formulated. The behaviour of bubbles in a model glass melting furnace has been examined using this model. The calculations involved soda-lime-silica glass containing sulphate ions and ions of iron as well as glass for the production TV panels with antimony and cerium. The results of calculations confirmed results acquired under isothermal conditions. The internal partial pressure of the refining gas, the bubble growth rate and the refining rate grew with the increasing initial redox state of glass in the glass for TV panels. In the glass containing sulphate ions, the driving force of refining (the sum of the internal partial pressures of SO₂ and O₂ in the melt) exhibited minimum at the medium values of the initial redox, so the bubble growth rate and the refining rate were highest either at very high or very low values of the initial redox state of glass. The coupled mathematical model of the redox state calculation and bubble behaviour has been used to calculate the final bubble properties for two bubble sources: glass batch and air coming from the furnace refractory materials.

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