Mullite, a mineral characterized by its high melting point, is an essential component of fireclay refractory bricks. It is formed during the manufacturing process of refractory bricks due to the high-temperature firing of clay and other materials.It is composed of alumina and silica, and has a unique crystal structure. Mullite has a melting point of 1840°C and is capable of withstanding extreme temperatures without losing its physical properties.
Apart from mullite, the raw materials used for fireclay refractory bricks consist of hydrated aluminum silicates with minor proportions of other minerals. The general formula for these aluminum silicates is Al2O3.2SiO2.2H2O, corresponding to 39.5 % alumina, 46.5 % silica, and 14 % water (H2O). The purity of these raw materials is essential to ensure the properties of the fireclay refractory bricks.
Refractoriness and plasticity are the two main properties needed in fireclay for its suitability in the manufacture of refractory bricks. A good fireclay should have a high fusion point (greater than 1580 deg C) and excellent plasticity. The variety of clays and manufacturing techniques allows the production of numerous brick types suitable to particular applications.
In conclusion, the presence of the mineral mullite in fireclay refractory bricks is what makes it a popular choice for high-temperature applications. Its unique properties allow it to withstand extreme temperatures and maintain its physical properties. The raw materials used in the manufacturing process of fireclay refractory bricks, along with the manufacturing techniques, play a significant role in ensuring its properties. Overall, fireclay refractory bricks are an essential component for numerous applications and industries, from steel production to glass manufacturing.