Magnesia-iron-aluminum spinel brick (MgO-FeO · Al2O3)
Magnesia-iron-aluminum spinel bricks not only have good thermal shock resistance and kiln-hanging properties, but are also relatively cheap, have low thermal expansion and thermal conductivity, and will not cause the shell to deform due to overheating, thereby causing energy loss. Therefore, It has been widely used in the firing zone of cement rotary kilns with stable atmosphere in modern kilns. In addition, magnesia-iron-aluminum spinel bricks should also have excellent structural flexibility to effectively extend the service life of the material. It can react with cement clinker to generate CaO-Al2O3-Fe2O3 compounds. At the same time, the diffusion of Fe2O3 components makes the reaction The area has been further expanded, resulting in better stability of the kiln skin. At the same time, the bonding structure of the bricks becomes more developed due to the action of Fe2O3, which significantly improves the adhesion and peeling resistance of the kiln skin. However, the disadvantage is that the magnesia-iron-aluminum spinel brick has poor resistance to oxidation and reduction, corrosion resistance and high temperature resistance, which to a certain extent restricts its application and development.
Magnesium calcium zirconium brick (MgO-CaO-ZrO2)
The so-called magnesia-calcium zirconium bricks are magnesia-calcium zirconium brick products formed by adding a certain dose of pre-synthesized calcium zirconate to the original ingredients. They not only have good thermal shock resistance and kiln-hanging properties, but also have high high-temperature strength and can It resists the erosion of Portland cement and solves the problem of easy hydration of magnesia-calcium bricks. In an environment of 1500°C, monocalcium zirconate (CaO · ZrO2) exists on the interface as an inactive compound. It does not react chemically with spinel, but affects refractory materials subjected to various changes in cement clinker. The penetration of chemical components acts as a barrier, thereby improving the chemical corrosion resistance of magnesia-calcium zirconium bricks; in an environment of 1200°C, zirconium oxide (ZrO2) easily reacts with compounds in cement clinker to form high melting point Monocalcium zirconate (CaO · ZrO2), magnesium silicate (Ca3MgSi2O8) and wollastonite (CaO · ZrO2, CaSi2O5), so the magnesium calcium zirconium brick has excellent corrosion resistance and kiln skin hanging performance, and it can also effectively It resists changes in the atmosphere in the kiln and is currently used in the firing zone of new dry cement kilns with good results and has prospects for promotion.