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Overview of corundum castables

Corundum castables are high-performance amorphous refractory materials with corundum (α-Al₂O₃) as the main crystalline phase, and the content of Al₂O₃ is usually ≥90%, consisting of the following components:

• Aggregate: high purity raw materials such as electrofused white corundum, plate corundum, electrofused brown corundum or zirconium corundum, vân vân., accounting for 70%~85% of the formula.
• Powder: corundum fine powder, activated alumina micro-powder, vân vân., used to fill the gaps of aggregate and enhance the compactness.
• Binding agent: calcium aluminate cement, silica sol or composite micropowder to enhance the high temperature binding strength.
• Additives: water reducing agent (such as sodium tripolyphosphate), coagulant promoter, stainless steel fibre, vân vân., to optimize the construction performance and mechanical strength.

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Properties of corundum castables

Advantages of corundum castables for steelmaking furnace

• Điện trở nhiệt độ cao: corundum castables can work stably in high temperature environment above 1800°C.
• Chống ăn mòn: it has excellent corrosion resistance to steel, slag and alkaline substances.
• Cường độ cao: with good mechanical strength, it can withstand the mechanical shock and thermal stress in the steelmaking process.
• Ổn định sốc nhiệt: It is not easy to crack when the temperature changes sharply, ensuring the long-term use of the furnace lining.

Corundum castable’s construction process and precautions

• Mixing specification: must use forced mixer, dry mixing 2 minutes before adding water (water 6%~8%), wet mixing 3~5 minutes until uniform.
• Time control: the pouring should be completed within 30 minutes after mixing, and it is forbidden to add water twice or return the material for mixing.
• Vibrating requirements: use inserted vibrator to pour in layers (each layer ≤ 400mm) to avoid particle stratification.
• Conservation conditions: demoulding after 24 hours of natural conservation, temperature control at 5~35℃, watering conservation is prohibited.

Difference Between Corundum Castable and Corundum-Mullite Castable

Corundum castable and corundum-mullite castable are both high-performance refractory materials, but they differ in composition and application.

Corundum castable is primarily made of alumina (Al₂O₃), offering excellent thermal stability, high strength, and resistance to corrosion, making it ideal for extreme high-temperature environments like steel furnaces and kilns.

On the other hand, corundum-mullite castable combines alumina with mullite (3Al₂O₃·2SiO₂), enhancing thermal shock resistance and reducing thermal expansion, which is perfect for applications requiring frequent temperature changes, such as ceramic kilns or incinerators.

Corundum castables production workshop

Application of castables in steelmaking furnaces

• Metallurgical industry: ladle package lining, LF furnace cover, blast furnace hot blast stove lining.
• Energy and power: circulating fluidised bed (CFB) boiler lining, cyclone separator, high temperature flue.
• Petrochemical and building materials: catalytic cracking device, cement rotary kiln coal injection pipe, ceramic kiln lining.