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Performance Characteristics of Refractory Materials for Blast Furnace Ceramic Cups

Release time:

2026-01-05 10:07

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The blast furnace ceramic cup is a critical internal lining structure for the hearth and bottom of modern large-scale blast furnaces, and it has been widely adopted both domestically and internationally in blast furnaces such as those operated by Baosteel and Shagang. Its primary function is to protect the carbon brick lining and extend the service life of a blast furnace campaign—typically reaching 10 to 20 years. The ceramic cup is located on the hot face of the carbon bricks, forming a “cup-shaped” lining that leverages its low thermal conductivity to confine the solidification isotherm of the 1150℃ molten iron within the ceramic layer. This prevents direct contact between the carbon bricks and the high-temperature molten iron and slag, thereby reducing iron penetration, alkali metal erosion, scouring, and thermal stress-induced damage. At the same time, the ceramic cup provides thermal insulation and energy-saving benefits, helping to lower the coke ratio.
Main constituent materials
The refractory materials used for blast furnace ceramic cups are primarily alumina-based (Al₂O₃) ceramic materials. Common types include:
Composite brown corundum bricks: Made primarily from brown corundum and silicon carbide, these bricks are formed under high pressure with the addition of a binder and then sintered in a reducing atmosphere. They exhibit excellent resistance to molten iron erosion but have relatively poor alkali resistance (and are now rarely used in large blast furnaces).
Corundum-mullite bricks: They have a high Al₂O₃ content (70–90%), and the mullite phase provides excellent resistance to thermal shock. Their resistance to slag erosion is moderate.
Microporous corundum bricks/microporous mullite bricks: They feature low porosity (<15%), small average pore size (<1 μm), and high bulk density (>3.0 g/cm³). They exhibit excellent resistance to permeation and erosion, making them a trend in development.
Plastic-phase composite corundum bricks: A plastic-phase binder is added to enhance high-temperature strength and resistance to spalling.
Sialon-bonded corundum bricks: The third-generation product, featuring strong resistance to molten iron, slag, and alkali erosion, with a service life exceeding 9 years.
Monolithic castables: A modern, advanced technology that uses corundum and silicon carbide as aggregates, combined with silica sol or nano-binders delivered via pump casting. These materials offer superior structural integrity, seamless construction with no brick joints, and enhanced resistance to erosion compared to traditional brickwork. They allow for rapid repair or new construction (e.g., in 5,500 m³ blast furnaces).
Carbon bricks (such as microporous or ultramicroporous carbon bricks) serve as the outer layer of the ceramic cup, providing high thermal conductivity and structural support.
Key Performance
High erosion resistance: resistant to molten iron corrosion, slag erosion, and destruction by alkali metals (K, Na, Zn).
Microporous structure: low porosity and fine pore size, effectively preventing molten iron penetration.
High-temperature stability: Load softening temperature > 1500℃, with excellent thermal shock resistance.
Structural Design: Self-locking and anti-floating features (such as tongue-and-groove joints and inclined designs), large-format bricks or monolithic casting, to prevent stress concentration and iron leakage through brick joints.
Applications and Advantages
Location: Ceramic pad at the furnace bottom (mullite-based) + ceramic cup lining on the furnace hearth sidewall (corundum-based), combined with tuyere/iron tap assembly bricks.
Advantages: Extending the lifespan of blast furnaces (with domestic first-generation furnaces lasting over 10 years), saving energy and reducing consumption, and forming a self-generated slag-iron protective layer.
Development Trends: Transitioning from brick masonry to monolithic casting; carbon-composite bricks (combining the high thermal conductivity of carbon bricks with the erosion resistance of ceramics); thin-walled furnace hearth designs.