Application of Silica Bricks in Coke Ovens

Silica brick is a type of refractory material contains more than 93% SiO2. Due to its advantages such as high refractoriness under load, good resistance to slags and good creep resistance, it is widely used in coke oven and can expand the service life and improve the production capacity of coke ovens. 

Silica brick generally contains 93%-98% SiO2 and 2.0%-7.0% impurities such as Al2O3, Fe2O3 and CaO. Common silica brick is mainly composed of tridymite, which accounts for 30%-70%; high quality silica brick is cristobalite, about 20%-80%. 

 

Its refractoriness is up to the content of SiO2 and impurities. The higher the content of SiO2, the lower the content of impurities, the higher its refractoriness. Its refractoriness is generally 1690℃-1730℃. 

 

Its softening temperature under load is as high as 1650℃, close to its refractoriness. The crystalline structure of tridymite works as skeleton to support the structure of the brick, so silica brick has a high softening temperature under load although some impurities have low melting point. 

 

Its chemical composition is SiO2, a typical acid oxide, so it has great resistance to acid slags. At the same time, CaO and Fe2O3 can form new compounds with SiO2, which have resistance to alkali oxides. 

 

Its true density indicates the transformation degree of quartz. The lower the true density the better. Low true density means quartz is transformed fully and has small residual expansion in the production process. 

 

With the development of coking industry, the requirement for silica brick is higher and higher. Some new types are developed such as high density, high purity and density and high thermal conductivity silica brick. 

1)High density silica brick

Increasing the density is one of the effective way to improve the quality and expand the service life and reduce the coking time. The density is required to be more than 2.38g/cm3 and its porosity should be less than 16%. 

 

2)High purity and density silica brick

It is made of pure quartzite(SiO2˃98%) with addition of mineralizing agent. 

 

3)High thermal conductivity silica brick

It is made by adding additives with high thermal conductivity and high density such as CaO, Cu2O, TiO2 and Fe2O3 to raw materials. It can effectively reduce coking time and improve the production capacity of coke ovens. 

 

Silica bricks enjoy the advantages of high purity, long service life, good thermal conductivity, high refractoriness under load, and good creep resistance. In addition, it has accurate size tolerance, pure color and luster appearance.