Iron ladle castable is a low-cement monolithic for iron ladle linings. Bauxite or corundum aggregates with Al2O3 of 60-85% are selected by slag-line conditions. Low-cement bonding and integral casting resist slag attack, thermal shock and metal penetration.
| Al₂O₃ content | 60% – 85%（按工况） |
|---|---|
| Bulk density (110℃×24h) | ≥ 2.55 g/cm³ |
| CCS (1100℃×3h) | ≥ 60 MPa |
| MOR (1100℃×3h) | ≥ 8 MPa |
| PLC (1350℃×3h) | ± 0.5% |
| Thermal shock (1100℃ water) | ≥ 8 次 |
| Service temperature | ≥ 1450℃ |
Iron ladle lining loss comes from three directions. First, thermal shock: an empty ladle shell can cool below 200°C, and pouring hot metal instantly heats the surface above 1300°C, a swing of over 1000°C. Second, slag attack: blast furnace slag and desulfurization slag contain CaO and FeO that react with SiO2 in the castable to form low-melting phases and dissolve the surface layer by layer. Third, mechanical erosion: the impact of metal streams and repeated build-up and release of slag shells at the slag line tear at the embrittled surface.
Wall damage is a dissolution-penetration-spalling cycle. Hot metal and slag first dissolve the bonding phase and fine particles, roughening the surface. Metal then penetrates along open pores, creating a transformed layer. When new minerals formed inside differ in thermal expansion from the original structure, spalling occurs. Raising Al2O3 alone cannot extend life indefinitely; porosity and matrix design matter equally.
The common solution is a low-cement castable (LCC). On the aggregate side, Al2O3 is selected between 60% and 85% according to slag-line severity, with dense bauxite or corundum coarse particles and optimized particle grading for maximum packing density. In the matrix, microsilica and reactive alumina micropowder form a needle-like mullite network around 1300°C, locking the matrix together - the key to hot strength and slag resistance. Calcium aluminate cement is limited to 3-6% for early strength without excessive CaO that lowers slag resistance.
The slag line is the life-limiting zone. With highly variable basicity of desulfurized hot metal slag, slag-line material needs higher erosion resistance, commonly achieved by raising Al2O3 with small additions of Cr2O3 or spinel, trading some thermal shock resistance for lower erosion rate. The bottom follows different logic: long metal contact and poor heat dissipation require penetration resistance and overall stability, with a thickened integral lining and partitioned casting around porous plugs.
Three points dominate: water addition, vibration time and the baking curve. Adding more than 0.5% above the recommended water raises porosity and accelerates slag attack; under-vibration leaves honeycomb defects at corners. Baking has two dehydration and phase-change peaks near 110°C and 350°C; too fast heating causes explosive spalling. A rate of about 25°C/h up to 600°C with a hold is recommended before final heating. Many "short life" problems trace back to baking rather than the material itself.
Henan Songrui New Refractory Materials Co., Ltd. customizes iron ladle castable formulations by ladle condition and provides on-site installation guidance.
Large-area spalling is usually structural, not slag erosion. Causes include too fast baking creating internal steam pressure, untreated casting joints causing lamination, and thermal shock decohesion of the surface layer. Uniform thinning is normal slag erosion.
Small local defects can be repaired with a matching patching material, but the patching material must match the old lining and the surface must be cleaned and prepared, otherwise the patch will detach. Large damage requires complete relining.
No. Higher Al2O3 improves slag resistance but reduces thermal shock resistance due to corundum expansion. Frequent empty-ladle cycling makes pure high-alumina linings more prone to spalling. Select within 60-85% by actual slag temperature and basicity, adding spinel if needed.
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