Low cement castable refers to the new type of castable containing little combined dosage. The cement dosage of refractory cement castables is generally 15% to 20%, while the cement dosage of low cement castables is about 5%, and some are even reduced to 1% to 2%. The purpose of reducing the cement dosage is to improve the refractory performance of the castables. The key point is the use of ultra-fine particles not exceeding 1μm. Its thermal shock resistance, slag resistance, and anti-erosion ability are significantly improved, exceeding similar refractory bricks. Further reduction of the binding agent content can produce ultra-low cement castables and cement-free castables. Low-cement castables mainly include three types: high alumina refractory castables, mullite refractory castables, and corundum refractory castables.
| Item/Grade | Clay | High Alumina | Corundum |
|---|---|---|---|
| ω (Al2O3) ≥/% | 45 | 75 | 92 |
| ω (SiO2) ≥/% | 50 | 12 | 5 |
| ω (CaO) % | 1.8 | 1.5 | 1.5 |
| Bulk Density(g/cm3) | 2.3 | 2.6 | 3 |
| Cold Crushing Strength/Mpa | 72 | 75 | 85 |
| Permanent Linear Change/±% | 0.3 | 0.5 | 0.5 |
| Max Service Temperature/℃ | 1450 | 1600 | 1700 |
| Water Needed/% | 6.0-6.5 | 6.0-6.5 | 4.0-5.0 |
Low cement refractory castables have a small volume change at high temperatures. This means that it can maintain better stability at high temperatures and is less prone to cracking or breaking. This is very important for the service life and performance of the refractory.
Low-cement refractory castables exhibit high resistance to oxidation at high temperatures. The unique material of low cement castables makes it effective in resisting oxidation and corrosion, extending the service life of the refractory. This makes low-cement refractory castables ideal for use in high-temperature working environments.
Low cement refractory castables have a lower cement content thus reducing carbon emissions and do not produce gases harmful to humans, making them less environmentally friendly than traditional refractory materials as they release less harmful substances during production and use. This makes it environmentally friendly and reduces the potential risk to human health and the ecosystem.
These materials such as high alumina sand, alumina, and silicon carbide in low cement castables have high hardness, high wear resistance, and anti-friction ability, and can withstand large wear and friction effects at high temperatures. Therefore it can withstand friction, impact, and abrasion at high temperatures and is not easily damaged or broken.
Foundry Molds:
Low cement castables are commonly used for manufacturing core molds in the casting process. They possess high-temperature stability and abrasion resistance, enabling them to withstand thermal shocks and wear during high-temperature casting.
Abrasive Tool Manufacturing:
Low cement refractory castables can be used in the production of abrasive tools such as grinding wheels and sharpening stones. They exhibit excellent wear resistance and high-temperature performance, making them suitable for grinding and polishing processes.
Lining for Power Boilers:
Low cement castables can be used as lining materials for power boilers to resist high temperatures, corrosion, and abrasion. They protect the boiler structure and enhance its service life.
Chimneys and Flue Gas Purification Equipment:
In the power generation industry, low cement refractory castables are used as lining materials for chimneys and flue gas purification equipment to withstand high-temperature gases and the corrosive effects of chemical substances.
Refining Units:
Low cement refractory castables are commonly used as lining materials for high-temperature equipment in refining units, such as cracking furnaces and reforming units. They resist high temperatures and corrosive media, ensuring the safe operation of the equipment.
Chemical Reactors and Storage Tanks:
In the chemical industry, low cement castables are used as lining materials in reactors and storage tanks to withstand high temperatures and corrosive chemicals, protecting the stability and durability of the equipment.
Coal Gasification Furnaces:
Low cement refractory castables are frequently used as lining materials in coal gasification furnaces. They can withstand high temperatures and chemical corrosion, ensuring the stable operation of the gasification furnace.
Coal Tar Facilities:
In the coal chemical industry, low cement castables are used as lining materials in coal tar facilities to resist high temperatures and the corrosive effects of media, safeguarding the stability and durability of the equipment.