What raw materials can be used for breathable brick products

The materials of breathable bricks are mainly sintered magnesia, magnesia-chromium, high alumina and corundum.

1, sintered magnesia breathable brick

Sintered magnesia material refers to a refractory material with a MgO content of more than 80%. It is classified as an alkaline refractory material. It has high refractoriness, strong corrosion resistance to alkaline slag, and is not corroded by Ca, CaO, and does not pollute molten steel. Its large thermal expansion coefficient and poor thermal shock resistance make the material easy to drop, which greatly reduces the service life of magnesia refractories.

2, magnesia chrome breathable brick

Magnesium-chromium materials are refractory materials with MgO, Cr2O3 as the main components, and periclase and pinite as the main mineral components. Because chromium ore is not lazy to steelmaking slag and has compatibility with other refractory materials, so , the appearance of magnesia-chromium materials has improved the lack of thermal shock resistance of magnesia materials.

3, high-alumina breathable brick

High-alumina materials refer to refractories with Al2O3 content greater than 48%, which have the characteristics of high cold and hot strength, good wear resistance, thermal shock resistance, drop resistance and good volume stability at high temperature. However, their resistance to slag corrosion and The infiltration performance is not good, and it lacks to resist the moisture and penetration of the slag to the bricks in the whole contract.

4, corundum breathable brick

Corundum-based materials refer to refractory materials with an Al2O3 content of more than 90 percent. Corundum is made of industrial alumina or bauxite after sintering or electro-melting. When industrial alumina is electro-melted, white corundum is obtained. The content of Al2O3 is more than 98.5%; when bauxite is used as raw material, general corundum is obtained; when iron filings are added, brown corundum is formed; when germanium stone or germanium oxide is added, germanium corundum is obtained, and Cr2O3 is added to obtain chromium Corundum, fused tabular corundum is a tabular corundum formed in a semi-molten state in an electric arc furnace at 1900-2000 degrees Celsius directly with industrial alumina as the main material. It is beneficial to the volatilization of volatile impurities such as Na2O, so it is also the process of self-purification and purification. The characteristics of plate-shaped alumina material are high thermal conductivity, good thermal stability, high temperature strength, strong corrosion resistance, and high production cost.

Under high temperature and vacuum, it is a better choice to use corundum as the main crystal phase of the breathable brick. At the same time, the melting point of Cr2O3 is 2275 degrees Celsius, which is higher than the melting point of Al2O3 (2050 degrees Celsius), and alumina and chromium oxide can form a continuous solid solution. The corrosion resistance of the solid solution composed of AI2O3-Cr2O3 to iron oxide or slag is significantly enhanced. The addition of a small amount of Cr2O3 can inhibit the excessive growth of alumina crystals, thereby reducing the internal stress of the crystals, which can improve the physical properties of the material. If Cr2O3 is involved too much, the growth rate of corundum grains will be seriously affected, and then the physical properties of the material will be reduced. Therefore, the introduction of an appropriate amount of Cr2O3 can improve the thermal shock stability, erosion resistance and corrosion resistance of the material, but from the perspective of environmental protection, The introduction of Cr2O3 will cause pollution to the environment, so the introduction of Cr2O3 should be carefully considered.

To complete the bottom blowing argon process of ladle permeable bricks, ladle permeable bricks must have excellent high temperature resistance, corrosion resistance, thermal shock resistance, high temperature volume stability and high strength, good air permeability, stable operation, accurate external dimensions, and molten steel penetration. Lesser features.