Application of silica mullite brick in cement rotary kiln

The silica mullite brick produced in my country have been widely used in large-scale cement rotary kilns of 2000-10000 t/d designed by ourselves. It is understood that some kiln shells are all made of silica mullite brick except for the firing zone of about 20m long, which is directly combined with magnesia bricks, and the castables for the front and rear kiln mouths of about 0.8m each (Figure 1). The rear part of the firing zone, the so-called secondary firing zone, is generally the same as the firing zone, using directly bonded magnesia brick, but the kiln skin is difficult to stabilize. Due to the poor thermal shock stability and low wear resistance of magnesia bricks, the joint part between the brick and the kiln skin is easy to peel off with the kiln skin, which affects the service life of this section. Peeling, corrosion resistance and significantly longer service life. For example: Zhejiang Yuyao Shunjiang Cement Company's 2 500 t/d cement rotary kiln 21.55m ~ 24.955m originally used direct-bonded magnesia-chrome bricks with a service life of 310d, and switched to silica-molded bricks (AZM1650) with a service life of 410d. The bricks were repaired and replaced three times within a year, and the red kiln appeared in the shortest three months. . However, the kiln lining was reconfigured, the secondary firing zone was changed to 1680 silica mullite brick, and the transition zone was 1650 silica mullite brick, and the service life of the kiln was as long as 15 months. The transition zone of the 2500 t/d kiln of Ningxia Shengjin Cement Co., Ltd. has been using silica mullite brick for more than 7 months, and no problems have been found, and they are still in use.

The temperature of the brick surface in the transition zone of the cement rotary kiln is about 1400 °C, and the temperature of the preheating zone, cooling zone and other parts is lower than that in the transition zone, that is, the firing zone is protected by the kiln skin, and the temperature of the brick surface is not high. The starting temperature of the load softening is above 1500 ℃, especially the product has a dense structure, which is composed of minerals with high hardness, corundum, silicon carbide, and mullite, and has excellent wear resistance. It is an ideal brick for the transition zone. The compressive strength and load softening temperature are significantly higher than those of anti-stripping high-alumina bricks. Its thermal shock stability, corrosion resistance, wear resistance, and thermal conductivity are not high, which are required by the process characteristics of the rear transition zone. The service life is 1.5 to 2 times that of anti-stripping bricks. It has good wear resistance and is more suitable for cooling belts, and its service life can reach more than two years, which is 3 to 5 times that of high alumina bricks.

Now, according to the use conditions of different sections of the rotary kiln, different grades of silica mullite brick with different properties have been applied.

In addition, high-alumina silicon carbide bricks are also widely used in steel, non-ferrous metals, chemical and other sectors.