Commonly Used Refractory Materials for Glass Melting Furnaces

Refractory materials are the main components of glass melting furnaces, which have a decisive impact on glass quality, energy consumption, and product costs. The future of glass melting technology depends to a certain extent on the progress of refractory production, manufacturing technology, and product quality improvement.

Commonly used refractory materials for glass melting furnaces are divided into four categories: fused casting refractory materials, sintered refractory materials, amorphous refractory materials, and insulating refractory materials. Each type of material contains several types. The chemical composition, physical properties, dimensional error, and appearance type of refractory materials should comply with national standards or industry standards, and the latest revised version should be selected, otherwise, they shall not be shipped.

Silica bricks are widely used in glass-melting furnaces, and the main component is silicon dioxide (SiO₂). The silica bricks used in glass melting furnaces require a SiO₂ content of more than 94%, a maximum operating temperature of about 1600~1650℃, and a density of 1.8~1.95g/cm³. The apparent porosity is required to be less than 22%. The larger the porosity, the worse the quality of the silica bricks. Most of the appearance of silica bricks is white crystals, and the microscopic composition is the crystals of tridymite. Since silica bricks undergo crystal transformation at high temperatures, the volume expands, especially at 180-270℃, and around 573℃, the crystal transformation is more intense. Therefore, in the process of kiln baking and cold repair, it is necessary to adapt to the crystal transformation of silica bricks and take appropriate measures such as elastic tension strips.

The main components of clay bricks for glass kilns are Al₂O₃ and SiO₂, with Al₂O₃ content between 30% and 45%, SiO₃ between 51% and 66%, density of 1.7-2.4g/cm³, apparent porosity of 12%-21%, and maximum use temperature of 1350-1500℃. In the glass industry, clay bricks are used to build the bottom of the kiln pool. The pool walls of the working part and the passage, the walls, arches, lower checker bricks, and the heat storage chamber flues. As the temperature rises, the volume of clay bricks will also expand. When the temperature exceeds 1450℃, the volume will shrink again.

The main component of mullite brick is Al₂O₃, and its content is about 75%. Because it is mainly mullite crystal, it is called mullite brick. The density is 2.7-32g/cm³, the open porosity is 1%-12%, and the maximum use temperature is 1500~1700℃. Sintered mullite is mainly used for masonry of heat storage chamber walls.