The Application of Refractory Materials Made From Andalusite in Steel Metallurgy

Currently, refractory materials made from andalusite generally include the following four types:

1. Fired bricks
2. Unfired bricks
3. Refractory fibers
4. Unshaped refractory materials, such as castables, ramming materials, and casting sands.

In China’s metallurgical industry, most Al₂O₃-SiO₂ series refractories experience volume shrinkage under high-temperature conditions. This shrinkage limits their performance and lifespan under high-temperature loads, thermal shock, and slag corrosion. However, the slight expansion property of andalusite improves these weaknesses, enhancing their durability.

Additionally, while China is rich in high-alumina bauxite resources, their high impurity content often leads to melting under high temperatures. Adding andalusite to bauxite increases the mullite phase, altering the matrix mineral composition and microstructure, thereby raising the load-softening temperature of the material. Consequently, refractory materials made from andalusite are primarily used in the metallurgical industry, specifically in the following areas:

• Blast Furnaces: Used for furnace tops to resist CO corrosion.
• Hot Blast Stoves: For furnace walls, checker bricks, furnace tops, and combustion chambers.
• Iron Tapholes: Includes taphole clay for sealing and coatings or ramming materials for the iron trough.
• Mobile Torpedo Ladles: For lining permanent layers and working layers with fired and unfired products, ensuring the optimal performance of andalusite-based SiO₂-C composite working layers.
• Iron Ladle Cars: For lining permanent and working layers.
• Tundishes: For permanent linings and replaceable linings, as well as for preparing low-cement and ultra-low-cement refractory castables containing finely crushed andalusite.
• Reheating Furnaces: For furnace walls and roofs using plastics and ramming materials.
• Auxiliary Equipment: Includes bricks for steel casting nozzle bases, blowing stopper heads, stirring tuyere bricks, anchoring blocks, and burner bricks for reheating furnaces, along with protective refractory coatings and low-cement refractory castables for burners.

Unshaped refractories with general purposes (including materials requiring high stability and cement based on andalusite) form mullite at relatively low temperatures (1350°C), which creates a "strong welding" effect on product surfaces.

Additionally, andalusite-based high-temperature materials find widespread applications in:

• Aluminum Industry: Pre-baked anode cells
• Glass Industry: Reheating furnaces
• Ceramic Industry: Kiln furniture
• Cement Industry: Rotary kilns

Andalusite is also used in the production of multiphase composite materials (e.g., andalusite-silicon carbide composite materials) and insulating ceramics.