What are the classifications of lightweight insulation bricks?

Lightweight insulation bricks have the advantages of light weight, heat insulation and heat preservation, but the pressure resistance, slag resistance and thermal shock resistance are poor, so most of them cannot directly contact the flame. What are the types of lightweight insulation bricks?

1. Lightweight silicon bricks. Lightweight silicon insulation brick is a heat-insulating refractory product with SiO₂ content of not less than 91% made of silica as the main raw material. The volume of lightweight silicon insulation bricks is 0.9-1.1g/cm³, the thermal conductivity is only half of ordinary silicon bricks, the thermal shock resistance is good, and its load softening starting temperature can reach 1600 °C, which is much higher than that of clay insulation bricks. Therefore, the use temperature of siliceous insulation bricks can reach 1550 °C. It does not shrink at high temperatures, and there is even a weak expansion. Lightweight silicon bricks generally use crystalline quartzite as raw material, and flammable substances such as coke, anthracite, sawdust, etc. are added to the batch, or gas foaming forms a porous structure.

2. Diatomite bricks. Compared with other lightweight insulation bricks, diatomaceous earth bricks have a small thermal conductivity. Its use temperature varies with purity. Generally below 1100 °C, because the shrinkage deformation of the product at high temperature is large. When using diatomite raw materials, it needs to be fired at a higher temperature, silica is converted into phosphorus quartz, and lime can also be added as a binder and mineralizing agent to promote the conversion of phosphorus quartz during firing, which is conducive to improving the heat resistance of the product and reducing erosion shrinkage at high temperature.

3. Clay insulation bricks. Clay insulation brick is a heat-insulating refractory product with AL2O3 content of 30-48% made of refractory clay as the main raw material. Its production process adopts burnout addition method and foam method. Light clay insulation bricks are widely used, mainly used in various industrial kilns without contact with molten matter and non-erosion other effects of heat insulation refractories, the use temperature is 1200-1400 °C.

4. Alumina heat insulation brick. Alumina thermal insulation brick products have high refractory and good thermal shock resistance, and are often used as high-temperature insulation layers for kilns. The use temperature is 1350-1500 °C, and the use temperature of high-purity products can reach 1650-1800 °C. Mainly made of electrofused corundum, sintered alumina and industrial alumina as raw materials for heat insulation and refractory products.

5. Lightweight mullite bricks. Heat-insulating refractory products made of mullite as the main raw material. Mullite heat-insulated refractory bricks have high temperature resistance, high strength, low thermal conductivity, direct contact with flame, and are suitable for lining various industrial kilns.

6. Alumina hollow ball brick. Alumina hollow ball bricks are mainly used for long-term use below 1800°C. It also has good chemical stability and erosion resistance at high temperatures. Compared with other lightweight insulation bricks, alumina hollow ball bricks have high safety use temperature, high strength and low thermal conductivity. The bulk density is also 50-60% lower than that of dense products of the same composition, and can withstand the impact of high-temperature flames.