Mullite refractory castable is an unshaped refractory material composed of porous mullite aggregate, binder, and various additives. Mullite is a high-quality refractory raw material, and this type of mineral is relatively rare. The specific ingredient ratio can be adjusted according to the actual situation of the boiler. The refractoriness of mullite is 1790℃. Mullite castables are usually used in steelmaking, ceramics, petrochemical, and incineration industries. They can also be used as working linings in direct contact with flames, and have excellent heat insulation and heat resistance.
| Item/Grade | KRMJ-55 | KRMJ-60 | KRMJ-65 | KRMJ-70 |
|---|---|---|---|---|
| ω (Al2O3) ≥/% | 55 | 60 | 65 | 70 |
| Bulk Density ≥/ (g/cm³) | 2.3 | 2.4 | 2.5 | 2.6 |
| Flexural Strength ≥/MPa | 7 | 7 | 8 | 9 |
| Compressive Strength ≥/MPa | 40 | 50 | 60 | 70 |
| Permanent Linear Change ≤/% | ±0.5 | ±0.5 | ±0.5 | ±0.5 |
The low coefficient of thermal expansion of mullite castables means that they undergo minimal dimensional changes when heated. The property helps prevent cracking, and spalling and ensures the integrity and service life of the refractory lining.
Mullite castables dry and cure quickly without visible cracking or damage. Their formulation and properties allow for shorter bake times than some other refractory materials, resulting in faster installation.
Mullite castables usually do not contain harmful substances such as asbestos and other harmful substances, and during their production and application, it usually does not release a large number of harmful gases or particles into the environment.
Their composition and microstructure help them withstand attack by abrasive particles, making them suitable for applications exposed to abrasives, corrosive gases, or mechanical friction, reducing material loss and extending service life.
Mullite castables can be used in ladles, ladle linings in the steel industry, or tundishes in continuous casting systems. They have excellent thermal insulation properties and are resistant to the corrosive effects of molten metal and slag.
Mullite castables are used for lining reactors, reformer tubes, flare stacks, furnaces, and other high-temperature equipment in petrochemical plants. Mullite castables have excellent thermal insulation and chemical resistance, making them suitable to withstand the harsh conditions encountered in the production of petrochemical products.
The main applications of mullite in the glass industry are glass-melting furnaces, regenerators, port neck and throat areas, etc. They help to improve the heat exchange process and increase the overall energy efficiency of the glass manufacturing process.
Mullite castables are widely used in the ceramic industry because of their excellent thermal stability, low thermal expansion, and chemical corrosion resistance. They are mainly used in kiln furniture, crucibles, saggers, Drying Shelves, kiln car bases, etc.