What Are the Characteristics of Silica Bricks for Use in Glass Kilns?
What are the characteristics of glass kiln silica bricks With the progress of process technology, the quality of silicon brick products has been significantly improved, and the technical performance has also been significantly improved. In order to adapt to the usage conditions of different parts of the cement rotary kiln, glass kiln silica bricks have also emerged. Let's follow the editor to understand its characteristics!
What are the characteristics of glass kiln silica bricks
With the progress of process technology, the quality of silicon brick products has been significantly improved, and the technical performance has also been significantly improved. In order to adapt to the usage conditions of different parts of the cement rotary kiln, glass kiln silica bricks have also emerged. Let's follow the editor to understand its characteristics!
(1) The product has a dense structure and good wear resistance
The main crystal phase of glass kiln silica bricks is composed of high hardness mineral corundum (Mohs hardness 9.0-9.2), silicon carbide (Mohs hardness 9.0-9.5), and mullite (Mohs hardness 7.0-7.5). The product has a high structural density, with a volume density generally ranging from 2.7 to 3.0g/cm3. The room temperature wear resistance of refractory materials depends on their strength and structural density. Materials with high strength and density have better wear resistance. The lining of cement rotary kiln has been subjected to long-term rolling friction of materials, and wear is one of the main reasons for the damage of refractory lining. Its density, strength, and wear resistance are significantly superior to anti stripping high alumina bricks and magnesium aluminum spinel bricks. Silicone refractory bricks have good performance in the secondary firing zone, filter zone, and other parts of the cement rotary kiln, and can be said to play a very important role in good wear resistance.
(2) High load softening temperature and good high-temperature performance
The load softening temperature of silica bricks is above 1450 ℃, higher than 1650 ℃. There are certain differences in the load softening temperature of products from different brands. The temperature of the refractory brick surface varies in different parts of the cement rotary kiln lining. The temperature of the secondary firing zone and the front transition zone reaches around 1400 ℃, which is higher than the temperature of the silica brick surface of the glass kiln in the firing zone (due to the protection of the kiln skin during firing, the temperature of the refractory brick surface is 900~1000 ℃). The load softening temperature index of these bricks also exceeds that of commonly used anti peeling high alumina bricks and phosphate high alumina refractory bricks (with a load softening temperature of 1300~1520 ℃).
Compared with the firing zone, the transition zone is susceptible to the influence of reducing atmosphere and heat load due to the lack of kiln skin protection. Its service life has always been a bottleneck problem for cement rotary kilns. Therefore, some cement plants use magnesium aluminum spinel products in the transition zone. According to the research on magnesia alumina spinel bricks used in the transition zone of a 5000t/d large cement rotary kiln in a certain factory, it is found that the magnesia alumina spinel refractory bricks used in the front transition zone are basically non corrosive. However, due to the deposition of alkali in the open pores, the structure becomes dense, causing different sections of the same refractory brick to form, causing the hot surface of the refractory brick to peel off and crack, causing damage to the inner lining. Due to its dense structure, especially the continuous SiO2 dense layer formed on the refractory brick surface, silicon refractory bricks prevent the infiltration of molten substances. In addition, the chemical properties of Al2O3, SiC, and SiO2 are stable, and they do not react violently with gases such as SO2, O2, CO2 generated in the kiln, and do not react chemically with cement materials. Therefore, they have strong corrosion resistance. Secondly, the thermal shock stability of glass kiln silica bricks is good. Because it contains a certain amount of SiC, as we all know, SiC has high thermal conductivity and low coefficient of thermal expansion, which significantly improves the thermal shock stability of the product. The 1100 ℃ water cooling test is more than 10 times, up to 46 times. Therefore, the silica brick for cement rotary kiln does not peel off or break, and can significantly improve the service life.
(3) Reduce the temperature of the kiln body and achieve good insulation performance
Thermal conductivity of silica bricks [2.3~2.5 W/(m ˙ K) Alkaline products [2.69-2.74 W/(m ˙ K) Low, therefore the insulation effect of silica bricks is relatively good. Glass kiln silica bricks are used in the secondary firing zone, transition zone, preheating zone, kiln tail, tertiary air duct, decomposition furnace and other parts of large rotary kilns. Compared with alkaline bricks, the surface temperature of the cylinder is reduced by more than 100 ℃.