Ceramics-Silikáty 39 (4) 121-129 (1995)

SOME CRITICAL POINTS OF THE GLASSMELTTNG PROCESS, PART 2 - BUBBLE REMOVING PHENOMENA

L. Němec

Bubbles may be removed from a glassmelt by dissolution or by separation, however, the dissolution process may be completed only at higher pressures. The simple relations expressing the influence of temperature, pressure and glass composition on the bubble separation process have been presented to demonstrate their significance. These theoretical equations have been compared with available experimental data. The results have shown the primary importance of reduced pressure, temperature and optimum refining agent concentration. The critical points of refining process at proposed conditions are heterogeneous bubble nucleation at reduced pressures, and composition changes by evaporation as well as corrosion of refractory materials at very high temperatures. The modelling of the refining process faces the theoretical problems with involvement chemical reactions of present gases and influence of precipitated layers on bubble boundaries into the model.