Today, with the rapid development of metallurgical technology, the technical requirements for refractory materials for ladles are also getting higher and higher. The corundum-based Al-Mg spinel castable with ultra-low cement bonding is characterized by good spalling resistance and alkaline ladle slag erosion resistance. The life of the ladle lining is significantly improved, the consumption is significantly reduced, and the molten steel is not polluted.
Aluminum Magnesium Spinel Castable
The corundum-based aluminum-magnesium spinel castable uses white corundum as the aggregate and white corundum powder, aluminum-magnesium spinel, and activated alumina as the matrix. Pure calcium aluminate cement is used as the binder, and sodium hexametamate and sodium lignosulfonate are used as the composite water reducer. It has the characteristics of load softening temperature greater than 1500 ℃, high flexural strength, high compressive strength, and easy construction. Compared with traditional corundum refractory castables, the corrosion resistance and spalling resistance are greatly improved, and the high-temperature strength of the castables is also improved.
The construction of corundum aluminum magnesium spinel castables is slightly different from traditional castables. Its main key lies in the following points.
- Retarding technology is one of the key technologies in the construction of magnesium-aluminum castables. According to the change of season and ambient temperature, retarders such as lignin sulfonate should be added in time. The setting time can meet the needs of pouring construction.
- Adding part of a super large aggregate and zircon powder into the castable is very beneficial to suppress the occurrence of cracks.
- The slag line material adopts a high MgO ratio, and some pre-synthesized aluminum-magnesium spinel powder is added to improve the slag erosion resistance of the slag line.
- During pouring construction, strictly control the amount of water added and vibrate evenly, which is of great significance to improve the service life of the castable.
Aluminum-magnesium spinel castables exhibit excellent corrosion resistance in ladle systems, and high-grade aluminum-magnesium spinel castables are not only used more and more widely in ladles. At the same time, it is also used in the fields of electric furnace covers, RH dipping pipes, seat bricks, and ventilation bricks.
Application of Al-Mg Spinel Castable in Ladle
Al-Mg spinel castables have been used in ladles for a long time. In the early 1990s, my country’s bauxite-based synthetic aluminum-magnesium spinel, a refractory raw material, was put into industrial production. A number of refractory research institutions and production enterprises in my country have successively developed a variety of alumina-based aluminum-magnesium spinel castables for ladles with different performances. Since a certain proportion of pre-synthesized magnesia-aluminum spinel is added to this type of castable, the corrosion resistance and peeling resistance of the castable are greatly improved. The use of aluminum-magnesium castables with better performance than water glass bonding. It has been used on various ladles and achieved good results.
The bauxite-based aluminum-magnesium spinel castable developed by a refractory factory has been tested in a steel factory’s 70t (DH vacuum spray gun blowing argon) ladle and 30t continuous casting ladle (continuous casting ratio not less than 94%). The average life expectancy was 1 and 114 times respectively. This is respectively improved 1～3 times than the aluminum-magnesium castable that water glass combines. In addition, a 25t continuous casting (continuous casting ratio greater than 70%) ladle in a steel plant uses aluminum-magnesium spinel castables, with an average ladle age of 77 times, which is 1.2 times higher than that of sodium silicate combined aluminum-magnesium castables. In addition, the aluminum-magnesium spinel castable is used for the 28t ladle in the steelmaking plant, with an average lifespan of 79 times, which is 1.6 times higher than that of the aluminum-magnesium castable combined with water glass. The bauxite-based aluminum-magnesium spinel castable is made of high-quality high-alumina bauxite clinker as aggregate, and high-quality high-alumina bauxite clinker powder, synthetic magnesia-alumina spinel powder and sintered magnesia powder as a matrix. Binders include polyphosphate, SiO2 micro powder, Al2O3 micro powder, pure calcium aluminate cement, etc.