High-Alumina Bricks in High-Temperature Furnaces

High-Alumina Bricks in High-Temperature Furnaces

1. Definition and Classification

High-alumina bricks are made mainly from bauxite clinker with Al₂O₃≥48%. Grades are classified by Al₂O₃: LZ-55 (≥55%), LZ-65 (≥65%), LZ-75 (≥75%), plus special grades—low-creep, spalling-resistant, micro-expansion and phosphate-bonded. Higher Al₂O₃ raises refractoriness, RUL and slag resistance, and price.

2. Properties

The mineral composition is mainly mullite and corundum; as Al₂O₃ rises the corundum ratio increases. Typical performance: LZ-55 refractoriness ≥1770℃, LZ-65 ≥1790℃, RUL up to above 1550℃; good hot strength, resistance to gas scouring and dense structure. Compared with fireclay, high-alumina offers higher temperature and load capacity; compared with corundum, better value—the typical balance of performance and cost. Low-creep and spalling-resistant grades optimize for specific failure modes.

3. Applications in Steel

Blast furnace: bosh, belly and lower stack use high-alumina and composite bricks against temperature, wear and alkali vapor; hot stove: domes and hot zones use low-creep high-alumina, hot-zone checkers use high-alumina grades; steelmaking: mixers, hot metal ladles and ladle permanent layers use large volumes of high-alumina; rolling: reheating furnace walls and roofs and soaking pits use high-alumina and spalling-resistant grades. Steel is the largest market.

4. Applications in Cement, Glass and Non-Ferrous

Cement: preheaters, precalciners, kiln hoods and hot grate coolers use high-alumina and spalling-resistant grades; transition and late burning zones use spalling-resistant and micro-expansion grades. Glass: upper checkerwork, tank walls and breast walls at medium-low temperature use high-alumina combined with low-porosity fireclay. Non-ferrous: furnace wall hot zones of copper and zinc smelters and rotary kiln transition zones use high-alumina. Petrochemical heaters, ceramic kilns and waste incinerators also use high-alumina widely.

5. Selection Essentials

① Choose the Al₂O₃ grade by zonal temperature and media—do not over-specify low-temperature zones; ② use low-creep grades for load-bearing zones and spalling-resistant for frequent temperature cycling; ③ consider micro-expansion grades for gas-tight zones; ④ match with high-alumina mortar for joint quality; ⑤ check dimension tolerance and appearance so masonry quality does not undermine brick performance.

6. Conclusion

High-alumina bricks are the general-purpose mainstay of high-temperature furnaces, offering high-temperature and slag resistance at strong value. Understanding their classification, property boundaries and applications enables rational zonal selection. Henan Songrui New Refractory Materials Co., Ltd. produces LZ-55/65/75 and the full special-grade range—low-creep, spalling-resistant, micro-expansion, phosphate-bonded—with duty-based customization.