Challenging Service Conditions of EAF Ladles

 

• Tapping temperature: 1640-1690°C
• Over 1000 steel grades processed
• Wide slag basicity range (CaO/SiO₂ ratio 0.5-5)
• Extended refining duration: 120-150 minutes
• High heating power input

 

Traditional solutions

 

• Alumina-Magnesia-Carbon bricks
• Alumina-Spinel-Carbon bricks
• Magnesia-Carbon bricks (carbon-containing pressed products)

 

New technology: Corundum-Spinel Castable

 

Advantages over conventional materials:

 

• Superior resistance to basic slag corrosion
• Enhanced high-temperature mechanical properties

 

Key features of corundum-spinel castable:

 

• Larger grain size
  Excellent chemical stability
• Low solubility
• Outstanding volume stability

 

Bao Steel trial implementation:

 

• Replaced Al-Mg-C bricks in 150t ladle bottoms
• Applied in round/billet production line

 

Comparative Performance Data

 

Service life:

Castable: 91-92 heats (normal retirement)

Brick lining: Requires full replacement at intermediate repair

 

Residual thickness:

Castable: >100mm in most eroded areas (impact zone)

Brick lining: Complete replacement needed

 

Operational Advantages of Monolithic Castable

 

Safety improvements:

 

• 80% reduction in joint seams (minimized steel penetration risk)
• Enhanced gas tightness (reduces side-blowing through porous plugs)
• Eliminates brick spalling during late service stage

 

Maintenance benefits:

 

• 60% shorter full repair time (2h vs 4h for bricklaying)
• Targeted repairs possible (impact zone patching only)
• 40% reduction in refractory consumption

 

Process optimization:

 

• Simplified mechanical installation
• Reduced labor intensity

 

Usage

 

Mix design:

Water addition: 5.0-5.5%

Flow value: 180-220mm

 

Construction:

Mixing time: 3-5 minutes

Vibration compaction

Total installation: 1-2 hours

Curing schedule:

16h curing + 36h preheating (vs 12-24h for bricks)

 

The successful trial at Baosteel demonstrates 25% longer service life compared to traditional brick linings, with 30% lower maintenance costs. This technology is particularly suitable for high-quality steel production requiring extended refining times.