Description of Low Cement Castables
Low cement castables are refractory mixes with a lower cement content. The amount of cement in refractory cement castables is usually 15-20%, while the amount of cement in low cement castables is about 5%, and in some cases it is even reduced to 1-2%. The purpose of reducing the amount of cement is to improve the refractory properties of the castable. Unlike traditional refractory castables, low cement castables contain less cement, so they have higher strength and better technical characteristics.
Physical and chemical indicators of low cement castables
Low cement refractory castables consist of corundum powder, high alumina and aluminous fillers and high alumina cement. In addition, special binders such as low temperature cement or its substitutes are added to the castable to promote the setting of the mixture at low temperatures. The particle composition can be changed according to the conditions of use and customer requirements, as well as the chemical composition of the castable.
Physical and chemical indicators of low cement castables
| Subject/Sort | Шамотная | Высокоглиноземистая | Корундовая |
|---|---|---|---|
| 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 |
| Прочность на холодное раздавливание/Мпа | 72 | 75 | 85 |
| Постоянное линейное изменение/±% | 0.3 | 0.5 | 0.5 |
| Максимальная температура эксплуатации/℃ | 1450 | 1600 | 1700 |
| Необходимое количество воды/% | 6.0-6.5 | 6.0-6.5 | 4.0-5.0 |
Advantages of low cement castables
Low cement content
The cement content of low-cement refractory castables is usually between 3% and 8%, which is significantly lower than the 15% to 30% of high-cement refractory mixes.
High density
Low cement content reduces the porosity of castings and improves their density, thereby increasing the compressive and bending strength of the material.
Fire resistance characteristics
Low cement refractory castables have high refractory properties and can usually withstand high temperatures of 1500-1800℃.
Good thermal stability
Low cement refractory castables have a low coefficient of thermal expansion, which allows them to remain dimensionally and structurally stable at high temperatures.
Good corrosion resistance
Low cement refractory castables can be designed with good corrosion resistance to meet specific requirements. They are resistant to acids, alkalis, corrosive gases and chemicals, so they are widely used in various fields of chemical, metallurgical and oil refining industries.
Increased resistance to temperature changes
Low cement refractory castables have a lower coefficient of thermal expansion and are better able to resist thermal expansion and contraction at high temperatures. This makes them more stable in environments with frequent temperature changes or large temperature gradients, reducing the possibility of cracking and damage caused by temperature changes.
Application of low cement refractory castables
Metallurgical industry
Low cement refractory castables can be used for the construction and maintenance of high-temperature furnaces such as steelmaking furnaces, ironmaking furnaces, converters, electric furnaces, and steelmaking furnaces, and can withstand the erosion of high temperatures and metallurgical slag.
Petrochemical industry
Low cement refractory castables can be used as refractory linings for high temperature and high pressure equipment such as catalytic cracking units, petroleum cracking furnaces, and hydrocracking units.
Energy
Low cement refractory castables can be used for refractory lining of thermal power plant boilers, coal-fired gas turbines and other thermal equipment resistant to high temperature and corrosive gases.
Cement industry
Low cement refractory castables can be used for lining cement production equipment such as cement kilns, rotary kilns, clinker silos, etc. They can withstand high temperatures and chemical reactions.
Glass industry
In high-temperature process equipment such as glass melting furnaces and glass kilns, low-cement castables can be used for lining insulation to ensure the fire resistance and thermal efficiency of the equipment.
