Guide to Choosing Refractory Linings for Industrial Furnaces

In high-temperature industrial sectors such as steel smelting, non-ferrous metal melting, ceramic firing, and glass production, industrial furnaces play a crucial role. The furnace lining, serving as the primary barrier against extreme heat and reactive materials, directly impacts production efficiency, product quality, and operational safety.

Temperature tolerance is the primary factor in lining selection. Different materials have varying refractory properties—the maximum temperature they can withstand without softening or melting. The selected material must exceed the furnace's peak operating temperature with an appropriate safety margin.

• Peak temperature: Identify the highest temperature reached during normal operation.
• Safety margin: Select materials with 50-100°C higher refractoriness than peak temperatures.
• Long-term stability: Consider performance degradation under sustained heat exposure.

The furnace atmosphere—including gas composition, slag characteristics, and material chemistry—significantly affects lining durability. Different materials exhibit varying resistance to chemical attack.

• Acidity/alkalinity: Acidic slags require silica or alumina linings; basic slags need magnesia-based materials.
• Oxidation-reduction: Consider redox conditions when selecting materials.
• Gas composition: Account for corrosive gases like steam or sulfur dioxide.

Material flow, impact, and abrasion can cause mechanical wear. Select linings with appropriate hardness and structural integrity.

• Particle size: Larger particles increase wear rates.
• Flow velocity: Faster-moving materials accelerate erosion.
• Impact frequency: Regular impacts require tougher materials.

Budget constraints influence material selection. Balance performance requirements with lifecycle costs.

• Material costs: Prices vary significantly by type and grade.
• Installation expenses: Some materials require specialized installation.
• Maintenance frequency: Consider long-term upkeep requirements.

Composed primarily of SiO₂, silica linings offer excellent thermal shock resistance at relatively low cost. However, their limited temperature tolerance (≤1700°C) and reactivity with steel oxides make them unsuitable for steel production.

With MgO content exceeding 86%, magnesia linings withstand extreme temperatures (≤2800°C) and resist basic slag corrosion. Their high thermal expansion makes them unsuitable for thin-walled induction furnaces.

Ceramic-based bricks provide durable, customizable solutions for diverse applications. Available in clay, high-alumina, silicon carbide, and magnesia compositions, they offer excellent thermal insulation but require careful installation to prevent cracking.

Al₂O₃-based linings (≤1900°C) excel in acidic environments like glass and ceramic furnaces. While offering superior thermal shock resistance and mechanical strength, they perform poorly against basic slags and carry higher costs.

• Silica: ≤1700°C, optimal for cast iron melting
• Magnesia: ≤2800°C, preferred for steel production
• Refractory bricks: High-stress, high-temperature industrial applications
• Alumina: ≤1900°C, ideal for acidic environments

Proper installation and regular maintenance significantly extend lining lifespan:

• Conduct thorough surface preparation before installation
• Use compatible bonding agents and control joint spacing
• Implement scheduled inspections and prompt repairs
• Monitor slag accumulation and remove deposits regularly

Selecting optimal furnace linings requires comprehensive evaluation of operational conditions, thermal requirements, chemical exposure, and economic factors. Appropriate material selection enhances furnace longevity, reduces maintenance costs, and improves production efficiency—ultimately strengthening industrial competitiveness.