Magnesia-chrome bricks, as the core refractory material for high-temperature industrial kilns, have a quality that directly impacts equipment lifespan, production efficiency, and operational safety.
In kilns in industries such as cement, glass, and metallurgy, inferior magnesia-chrome bricks can cause various problems and even lead to safety accidents. Therefore, it is crucial to master scientific selection methods and correctly choose high-quality refractory bricks.
1.Core performance of magnesia-chrome bricks
First, refractoriness. High-quality magnesia-chrome bricks typically have a refractoriness of no less than 1800°C, ensuring they resist softening and deformation in high-temperature environments.
Magnesia-Chrome Brick
Second, thermal shock resistance. This property is reflected in the resistance to cracking and spalling during sudden temperature changes. This is particularly important in environments where kilns are frequently started and stopped.
Furthermore, the corrosion resistance of magnesia-chrome bricks should be considered when selecting them. The chromite phase in high-quality bricks effectively resists corrosion from alkaline slag, acidic gases, and metal oxides.
Of course, these properties do not exist in isolation; they depend on the raw material ratio and microstructure. The appropriate combination of high-purity magnesia and chromium ore can form a stable periclase-chromite phase, improving overall performance stability.
2.Raw materials and production process: determine the intrinsic quality of the brick
Raw material purity is the foundation of high-quality magnesia-chrome bricks.
Specifically, the MgO content of magnesia sand should be no less than 95%, and impurities should be controlled within 3% to prevent the formation of low-melting-point phases that reduce high-temperature strength. The Cr₂O₃ content of chrome ore is recommended to be above 35%, and the lower the content of oxides such as iron and silicon, the better.
magnesia-chrome brick
More importantly, the production process directly affects the density and uniformity of the brick. Therefore, high-pressure forming and high-temperature firing are crucial.
However, it is important to note that while high-pressure forming can increase density, it must be combined with a sufficient firing temperature. Otherwise, sufficient sintering may be difficult to achieve, affecting the brick’s strength and corrosion resistance.
3.Different kilns have different choices
The performance requirements for magnesia-chrome bricks vary significantly across different industrial scenarios.
For example, the firing zone of a cement rotary kiln must withstand high temperatures and alkaline corrosion, so high-chromium, high-density bricks are recommended.
The roof of an electric furnace, on the other hand, prioritizes thermal shock resistance, so a small amount of zircon can be added to improve thermal shock stability.
rotary kiln
Given these differences, the selection process requires careful consideration of parameters such as the kiln’s temperature profile, atmosphere (oxidation/reduction), and medium composition.
In short, avoid blindly pursuing high chromium content while ignoring actual operating requirements, which can lead to performance degradation or incompatibility issues.
Of course, in addition to the product itself, selecting an experienced refractory supplier is also crucial. A high-quality supplier can provide high-quality magnesia-chrome bricks tailored to specific operating conditions.
