Characteristics and application cases of mullite-corundum castables

        The lining of a large pelletizing roaster introduced by a steel company in Liaoning was mainly casted with corundum castables. After three months of ignition operation, the lining and the lining of the combustion chamber produced multiple large-scale peeling. The effect was very unsatisfactory. The reason for the large area flaking is probably due to the large thermal expansion coefficient of the corundum furnace material and the high modulus of elasticity. Therefore, the thermal shock resistance and the anti-flaking property are not good.

        Composite refractories composed of two or more minerals or phases with some differences in thermal expansion coefficient tend to have better thermal shock resistance and spalling resistance. We used a new type of mullite-corundum castable for a steel company to pour the pellet furnace lining. After being used by a steel company in Liaoning, it received a very good effect. The pellet furnace was operated for 1 year. No signs of peeling were found, which greatly increased the life of the pellet furnace.

        The aggregate of castables is made of high-purity electrofused mullite produced by our factory. The fused white corundum fine powder produced by our factory is used as the main matrix material, and a small amount of active silica fume (SiO, fine powder recovered by ferroalloy plant) is introduced. Kyanite powder and additions such as sodium tripolyphosphate or sodium hexametaphosphate. On the basis of the initial success of the use of pellets in a steel company in Liaoning, we prepared a precast block of mullite-corundum low-cement castable for a large pellet furnace of a steel company in Inner Mongolia, which was built in a pellet furnace. The hot spot of the room is compared with the corresponding combustion chamber built with high alumina bricks. After three months of ignition operation, the masonry of the high-aluminum brick masonry was severely peeled off, and the mullite and corundum precast block masonry built in the combustion chamber corresponding to the local bonfire was intact and there was no peeling. produce. After 6 months of re-ignition operation of the high-aluminum brick masonry after cold repair, it was observed that the high-aluminum brick masonry had been peeled off and damaged seriously due to mechanical failure. The mullite-corundum castable precast block masonry still showed no obvious signs of peeling off.

        The flame temperature of the above-mentioned pellet furnace combustion chamber can be as high as 1700 °C. The thermal shock is also harsh. The preliminary trial results show that we have cooperated with the relevant units to develop and produce mullite-corundum castables and precast blocks with pure corundum castables and high alumina bricks. It has better thermal shock resistance and spalling resistance. It can be expected to obtain better use effect when it is used at high temperature with severe thermal shock. It is a new type of advanced castable and precast block worthy of promotion. We are willing to work with each We will cooperate with the manufacturers to provide dedication to the use of such castables and prefabricated blocks in each unit of use.