For many years, silica has been the preferred melter crown refractory for air-fuel-fired furnaces. Silica refractory brick are relatively low in cost yet quite serviceable, with their service life usually that envisioned for the glass-melting furnace campaign. This standard for conventional silica for air-glass melters has been a low flux factor (defined by ASTM as Type A where the amount of Al203 plus twice the amount of alkali must be 0.50% or less) or super-duty silica brick. These products give good performance. A few years ago, when soda-lime furnaces were converted to oxy-gas combustion systems, the life of silica superstructure, particularly the melter crown, became somewhat shorter. This paper gives ten points to consider when looking at silica bricks for long melter crown life with oxy-gas melters.
