Tabular alumina is a high-purity, fully sintered alumina produced without additives such as MgO or B₂O₃. It is fired at temperatures close to the melting point of alumina, forming large, well-developed α-Al₂O₃ crystals with a characteristic plate-like structure. This unique microstructure provides excellent dimensional stability, thermal shock resistance, and reliable performance in high-temperature environments.
Since the 1950s, tabular alumina has been widely used as a premium refractory aggregate. The introduction of high-purity calcium aluminate cement and phosphate-bonded systems has further improved the durability and service life of refractory products.
1. Properties of Tabular Alumina
Conventional sintered alumina is typically produced with small amounts of sintering additives, resulting in a fine-grained structure and relatively lower thermal shock resistance.
By comparison, tabular alumina is rapidly sintered at temperatures above 1,900°C without any additives. Its unique structure gives it several important advantages:
● Large, well-developed α-Al₂O₃ plate-like crystals.
● Low open porosity with closed pores inside the crystals.
● A melting point of about 2,040°C and Mohs hardness of 9.
● Excellent resistance to most acids and alkalis, except hydrofluoric and phosphoric acids.
● High mechanical strength, excellent thermal shock resistance, and good thermal conductivity.
| Aggregate Type | Residual Strength After Thermal Shock (%)20–1300–20°C Cycle | Residual Compressive Strength After Thermal Shock (kg)20–1300–20°C Cycle | Crushing Strength (kg) | Bulk Density (g/cm³) | ||||
|---|---|---|---|---|---|---|---|---|
| 10 Cycles | 20 Cycles | 30 Cycles | 10 Cycles | 20 Cycles | 30 Cycles | |||
| Tabular Alumina | 95 | 87 | 73 | 170 | 118 | 80 | 296 | 3.66 |
| Fused White Alumina | 68 | 19 | 0 | 21 | 4 | 0 | 105 | 3.89 |
| Fused Brown Alumina | 62 | 10 | 0 | 38 | 5 | 0 | 195 | 3.97 |
| Bauxite | 82 | 53 | 20 | 43 | 30 | 12 | 242 | 3.26 |
Note: Crushing strength refers to the load required to crush the particles under compression.
As a refractory aggregate, tabular alumina offers high refractoriness, high density, low permeability, low thermal shrinkage, excellent wear resistance, and high purity.
2. Applications of Tabular Alumina in Steel Industry Refractories
Because of its outstanding performance, tabular alumina is widely used in refractory products for the steel industry. It serves as an aggregate in Al₂O₃-C, Al₂O₃-SiO₂-C, and Al₂O₃-Cr₂O₃ refractories, and is also used in high-alumina monolithic refractories.
In many applications, tabular alumina can replace fused alumina or white fused alumina, providing improved durability and thermal stability.
| Equipment | Application Area | Recommended Refractory Materials | Key Performance Advantages |
|---|---|---|---|
| Blast Furnace | Furnace lining, hot blast stove, iron runner, taphole | Alumina bricks, high-alumina bricks, high-alumina castables, high-alumina ramming mixes, alumina refractory concrete | Excellent thermal shock resistance, slag resistance, and corrosion resistance |
| Torpedo Ladle | Working lining, iron runner, transfer trough | Alumina castables, alumina bricks, alumina ramming mixes, prefabricated shapes | Excellent thermal shock resistance, good wear resistance, and long service life |
| Steel Ladle | Working lining, tuyere area, nozzle seat | Alumina castables, alumina ramming mixes, alumina bricks, high-alumina precast shapes, alumina refractory concrete, nozzle blocks, slide gate components | Excellent thermal shock resistance, good slag resistance, slow wear rate, and low gas permeability |
| Tundish | Working lining, cover | Low-cement castables, high-alumina dry vibration mixes | Stable performance and long service life |
| RH Degasser | Immersion tube, circulation tube | Tabular alumina bricks, prefabricated shapes | Excellent thermal shock resistance and slag resistance |
| Nozzle System | Long nozzle, submerged entry nozzle (SEN) | Alumina nozzles, alumina sleeves, and related components | Excellent thermal shock resistance and wear resistance |
| Sliding Gate System | Slide gate plate, slide gate nozzle | Alumina slide gate nozzles, tabular alumina castables, alumina sleeves | Excellent thermal shock resistance and corrosion resistance |
| Reheating Furnace | Working lining | High-alumina plastics, castables, prefabricated blocks | Excellent dimensional stability and thermal insulation performance |
Its applications include blast furnaces, hot blast stoves, torpedo ladles, basic oxygen furnaces, secondary refining furnaces, steel ladles, tundishes, soaking pits, and reheating furnaces. Beyond the steel industry, tabular alumina is also used in ceramic kiln furniture, electrical insulators, catalyst supports, and other high-temperature applications that require high strength, high purity, and excellent thermal stability.
