Refractory materials for electric furnaces

An electric arc furnace is a steelmaking device that uses the electric arc generated between the electrode tip and the furnace charge as heat energy. An electric arc furnace consists of a furnace top, furnace wall, furnace bottom, and tapping trough.

1. Refractory Materials for Electric Arc Furnace Roofs

High-alumina bricks are commonly used for electric arc furnace roofs, with an alumina content between 75% and 85%. Compared to silica bricks, high-alumina bricks are characterized by higher refractoriness, better thermal shock resistance, and higher compressive strength. Due to the abundance of bauxite resources in China, high-alumina bricks have become the main refractory material for electric arc furnace roofs, with a service life approximately 2-3 times that of silica brick roofs.

Precast blocks for electric arc furnace roof by electric arc furnace refractory material manufacturers (as shown in the figure below) can also be used. Compared to conventional masonry roofs, these components offer advantages such as easier construction, better overall integrity, stronger resistance to electric arc radiation, and better resistance to rapid heating and cooling.

2. Refractory Materials for EAF Furnace Walls

The furnace walls, slag line zone, and hot spots are the weakest points of the furnace wall. Magnesia-carbon bricks or alumina-magnesia-carbon bricks are generally used, exhibiting excellent high-temperature resistance and slag resistance. Their service life is significantly extended, reaching over 300 heats.

To ensure more even damage to the furnace wall and extend its service life, water-cooled boxes or jackets are also installed in the furnace walls. A layer of refractory coating is sprayed onto the inner surface to form a protective layer for the slag, effectively reducing the unit consumption of refractory materials, but the corresponding energy consumption increases.

3. Refractory Materials for the EAF Furnace Bottom

The EAF furnace bottom is where the furnace charge and molten steel converge. When the furnace bottom lining reacts with slag and iron oxide to form a modified layer, it can become porous during reduction due to the reduction of certain components, often leading to floating due to molten steel intrusion. Therefore, the masonry or knotted lining in this area should possess advantages such as uniform overall performance, tight construction, good high-temperature performance, high strength, corrosion resistance, erosion resistance, good thermal shock resistance, and volume stability.

Therefore, the furnace bottom is generally constructed using magnesia-carbon bricks. If monolithic refractories are used Hearth Dry Ramming Mass is ​​required for ramming, and Hot Repair Mass is ​​needed for repair.

4. Refractory Materials for the Taphole

Currently, electric arc furnaces generally use an eccentric tapping outlet method at the furnace bottom. The refractory materials typically used are magnesia-carbon bricks or alumina-magnesia-carbon bricks.

5. Refractory Materials for Tap Hole 

The slag tap filler in electric furnaces is mainly used to protect the slag tape structure, prevent erosion by high-temperature molten slag, and possess refractory and corrosion-resistant properties. Generally, magnesia olivine sand with a magnesium content of 55%-70% is used as the EAF Slag Hole Repair Sand.

6. Refractory Materials for Electric Furnace Repair/Spraying

Refractory materials for electric furnace repair need to possess properties such as rapid repair, high-temperature resistance, and corrosion resistance. They mainly use two types: repair materials and plastic repair materials.

Repair materials generally use magnesia-based repair spray mass.

The main components are fused magnesia (MgO>96%) and silicon carbide (SiC>98%). They are bonded by high-temperature asphalt and phenolic resin composites, and a double-layer spraying process is used to achieve rapid repair. Technology in 2025 shows that its sintering temperature reaches 1200℃, the repair thickness can reach 150mm, the room temperature compressive strength is ≥50MPa, and the strength retention rate after smelting at 1680℃ exceeds 85%. Suitable for high-temperature areas such as converter surfaces and induction furnace tops, it can extend the furnace lining life by more than 100% without kiln shutdown maintenance.