Application of firebrick
According to the different composition of refractory brick, it can be divided into five categories: silica alumina refractory brick, basic series refractory brick, carbon containing refractory brick, zirconium containing refractory brick and heat insulation refractory brick. Any furnace is not built with only one kind of refractory brick, which needs to be used with different refractory bricks. The composition of these five types of refractory bricks are introduced in detail.
1. It is reported that the basic theory of silica alumina refractory brick is based on the phase diagram of the binary system of Al2O3-SiO2, which mainly includes the following types.
（1） Silica brick refers to the refractory brick with more than 293% SiO2, which is the main variety of acid refractory brick. It is mainly used for masonry coke oven, also used for various glass, ceramic, carbon calciner, refractory brick thermal kiln vault and other load-bearing parts, also used in high temperature load-bearing parts of hot blast stove, but it is not suitable to be used in thermal equipment below 600 ℃ and with large temperature fluctuation.
（2） Clay brick is mainly composed of mullite (25% - 50%), glass phase (25% - 60%), cristobalite and quartz (up to 30%). Usually, hard clay is used as raw material, the mature material is calcined in advance, and then the soft clay is mixed to form clay brick products by semi dry or plastic method at 1300-1400c. A small amount of water glass, cement and other binders can also be added to make unfired products and amorphous materials. It is commonly used in blast furnace, hot blast stove, heating furnace, power boiler, lime kiln, rotary kiln, ceramic and firebrick firing kiln.
(3） The mineral composition of high alumina refractory brick is corundum, mullite and glass phase. Its content depends on the ratio of al2o3gsio2 and the type and quantity of impurities. The grade of refractory brick can be divided according to the content of Al2O3. The raw materials are high alumina bauxite and sillimanite natural ores, as well as clinker mixed with fused corundum, sintered alumina, synthetic mullite and calcined with alumina and clay in different proportions. It is usually produced by sintering. But the products also include fused cast brick, fused grain brick, unburned brick and amorphous refractory brick. High alumina refractory brick is widely used in iron and steel industry, nonferrous metal industry and other industries.
（4） Corundum refractory brick, corundum brick is a kind of refractory brick with alumina content not less than 90% and corundum as the main phase, which can be divided into sintered corundum brick and fused corundum brick.