Refractory Corrosion and Glass Defects

The refractory materials used in glass furnaces are exposed to high temperature and mechanical corrosion during the operation, which results in corrosion of refractories and glass defects. 

Silica brick is a kind of acid refractory mainly made from tridymite, cristobalite and a small amount of residual quartz as well as glass phase. Its main crystal phase consists of quartz, tridymite and cristobalite. The uneven distribution of mineralizing agent may cause crystalline silicate, wollastonite and hedenbergite. Silica brick is mainly used in the crown and breast wall of glass furnaces. The main corrosion of silica brick is caused by the alkaline components in the batches and the alkali vapor, which results in the glass stones. The main crystal phase of the stones is re-crystallization of tridymite. 

 

Alumina-silica refractories, including fireclay brick, high alumina brick, silimanite brick and mullite brick, is mainly used in the lower part of the pool, the wall of forming section and the checker works. Due to the alkali components of glass liquid, those refractories generally generate metamorphic minerals, including secondary re-crystallization mullite, grown corundum, beta-alumina oxide, nepheline, feldspar, etc.. Symbiosis of clay clinker and metamorphic minerals may remain in the stones. The crystal characteristics of this minerals is the staggered symbiosis of several minerals. 

 

Fused cast AZS block is made from pure alumina powder and Zircon sand (composed of 65% zirconia and 34% SiO2) with additions of Na2O and K2O. Its crystal phase consists of corundum, baddeleyite and glass phase. The baddeleyite may react with the alkali components in the glass liquid and corundum may produce beta alumina oxide and nepheline. Fused cast AZS block exudation is thought as the leading cause of knot and cord defects. 

 

Fused zirconia mullite bricks is made from natural high bauxite, iron bauxite, pure alumina powder, fireclay and some zircon. Its main crystal phase consists of mullite and a small amount of corundum and single baddeleyite. When contact with glass liquid, mullite may react with the alkali components in the glass liquid. Alkaline components can promote the decomposition of molten mullite and precipitate granular corundum crystals. The reaction of glass phase with alkali components results in nepheline,triclinic nepheline and star-shaped baddeleyite. Finally the corrosion results in glass defects. 

 

Sunrise offers various refractory materials for glass furnaces including fused cast AZS, silica brick, fireclay brick, high alumina brick, silimanite brick, mullite brick, etc..