How To Prolong The Life of Melting Furnace Refractory Materials

author: Alice

2025-03-26

Melting furnace refractory materials are special materials used for lining of high-temperature industrial equipment (such as electric arc furnaces, steelmaking furnaces, metallurgical furnaces, glass kilns, cement kilns, etc.), which can withstand extreme temperatures, chemical erosion and mechanical wear.

Application of Refractory Material

Iron & steel industry: blast furnace (carbon bricks), converter (magnesia carbon bricks), ladle (aluminum-magnesium castables).
Glass industry: melting furnace (silicon bricks, zirconium corundum bricks).
Cement industry: rotary kiln (high-aluminum bricks, magnesia-iron spinel bricks).
Chemical/electricity: gasification furnace (chrome corundum bricks), boiler (refractory castables).

Life Maintenance of Melting Furnace Refractory Materials

Extending the service life of melting furnaces refractory material is the key to reducing production costs and improving equipment operating efficiency. The following summarizes specific measures from the aspects of material selection, construction process, operation and maintenance:

1. Optimize the selection of refractory materials

Match working conditions

Temperature: Select materials with a refractoriness 100~150℃ higher than the actual working temperature (such as 1950℃ corundum bricks for 1800℃ working conditions).
Chemical erosion: Use silica bricks for acidic environments, magnesia bricks for alkaline slag, and magnesia carbon bricks (MgOC) for high FeO slag.
Thermal shock stability: Use silicon carbide bricks or zirconium-containing mullite bricks for furnaces that are frequently started and stopped.

Upgrade material performance

Use high-purity raw materials (such as high-alumina bricks with ≥99% Al₂O₃) to reduce low-melting impurities.
Add anti-corrosion components (such as adding antioxidant metals Al and Si to magnesia carbon bricks).

2. Strict construction and furnace baking process

Construction quality control

When laying shaped bricks, control the brick joints to ≤1mm and use special refractory slurry (such as phosphate binder).
Amorphous materials (casting materials) need to be fully vibrated to avoid pores or stratification.

Scientific furnace drying

Slowly heat according to the heating curve (such as 24~72 hours) to avoid rapid evaporation of water and cause explosion.
Extend the insulation time in the critical temperature section (such as 200~600℃) to ensure complete transformation of the bonding phase.

3. Key measures for operation & maintenance

Temperature control

Avoid over-temperature operation (such as overheating of the short net of the electric furnace causing local melting loss).
Reduce rapid cooling and heating, and use step cooling when stopping the furnace (50~100℃ per hour).

Slag management

Adjust the slag basicity (CaO/SiO₂ ratio) to reduce the erosion of refractory material.
Clean the slag on the furnace wall regularly (such as mechanical slag removal or gunning repair for the ladle).

Mechanical protection

Avoid direct impact on the refractory layer when adding materials (such as eccentric charging for melting furnaces).
Use prefabricated parts or reinforced guard plates for vulnerable parts such as furnace doors and steel outlets.

4. Active maintenance & repair technology

Online monitoring

Infrared thermal imager detects the temperature distribution of the furnace lining and finds local hot spots.
Ultrasonic thickness gauge monitors the remaining thickness of the refractory layer.

Repair technology

Gunning: Use a spray gun to spray refractory slurry (such as Al₂O₃SiO₂ series gunning material) to repair local spalling.
Hot repair: Directly throw self-flowing castables at high temperature (applicable to blast furnaces and rotary kilns).
Coating protection: Coat the surface of the furnace lining with an anti-permeability coating (such as ZrO₂ coating to block molten steel penetration).

5. Typical cases & improvement directions

Improved ladle life

Original problem: Aluminum-magnesium castables are corroded by molten steel penetration.
Improvement: Use castables containing spinel (MgAl₂O₄), and the life is increased from 80 times to 150 times.

Glass kiln arch optimization

Original problem: Silica bricks corrode under alkali vapor.
Improvement: Use dense zircon bricks (ZrSiO₄), which extend the service life by more than 2 years.

Through comprehensive optimization of materials, processes and operations, the service life of melting furnace refractory materials can be increased by 30%~200%. Targeted solutions need to be formulated according to specific furnace types (such as induction furnaces and rotary kilns).

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