High Alumina Brick

High alumina brick is a silicate-alumina refractory material made from high-alumina bauxite clinker as the main raw material, mixed with soft clay or chemical binders, formed, and then fired at about 1500°C. Its Al₂O₃ content is above 48%. According to Al₂O₃ content, high alumina bricks are usually divided into three grades: Grade I high alumina brick (Al₂O₃ > 75%), Grade II high alumina brick (Al₂O₃ 60%~75%), and Grade III high alumina brick (Al₂O₃ 48%~60%).

The main mineral composition of high alumina brick is mullite and corundum phases. The higher the Al₂O₃ content, the more corundum phase, and the better the refractoriness and erosion resistance. High alumina brick is a neutral refractory material, with certain resistance to both acidic and basic slag. However, due to its SiO₂ content, its resistance to basic slag is weaker than its resistance to acidic slag.

According to the national standard GB/T 2988-2023 “High Alumina Brick”, high alumina bricks are divided into two major categories: ordinary high alumina brick and low-creep high alumina brick, suitable for high-temperature kilns.

Product Advantages

• High refractoriness
  The refractoriness of high alumina brick reaches 1750~1790℃, higher than clay brick and semi-silica brick, making it an advanced refractory material. Refractoriness increases with Al₂O₃ content.
• Relatively high refractoriness under load
  Due to high Al₂O₃ content, few impurities, and little easily fusible glass phase, the refractoriness under load of high alumina brick is higher than that of clay brick, generally between 1420~1550℃.
• Good slag resistance
  High alumina brick is close to a neutral refractory material and can resist erosion by both acidic and basic slag. Products with low porosity formed by high-pressure pressing and high-temperature firing have higher slag resistance.
• Good thermal conductivity
  High alumina brick has less glass phase with low thermal conductivity and more mullite and corundum crystals with good thermal conductivity, so its thermal conductivity is better than that of clay brick.
• High-temperature volume stability
  Low-creep high alumina brick deforms very little under long-term high temperature and load, ensuring the long-term structural integrity of the kiln lining. It is especially suitable for high-temperature load-bearing parts such as hot blast stove domes and combustion chambers.
• Moderate thermal shock resistance
  The thermal shock resistance of high alumina brick is between that of clay brick and silica brick (about 3~5 cycles at 850℃ water cooling) and can be improved by optimizing particle grading.

Applications

High alumina brick is widely used in the linings of high-temperature kilns in metallurgy, building materials, glass, ceramics, and other industries:

Metallurgy Industry

• Blast furnace: Stack, belly, hearth, and other parts; grades GL-48, GL-55, GL-65
• Hot blast stove: Dome, combustion chamber, regenerator checker bricks; low-creep high alumina brick is the first choice for high-temperature load-bearing parts
• Electric furnace: Electric furnace roof; grades DL-80, DL-75, DL-65
• Steel ladle: Ladle lining, continuous casting tundish
• Casting system: Stopper heads, nozzle bricks, etc.

Building Materials Industry

• Cement rotary kiln: Transition zone, lining before and after the burning zone
• Glass melting furnace: Regenerator furnace wall and checker bricks

Other Industries

Carbon baking furnace, carbon calcining furnace

Coke oven, soaking pit

Boiler, reverberatory furnace, blast furnace

Selection Recommendations

The selection of high alumina brick should be comprehensively determined according to service temperature, erosion medium, and load conditions:

• The higher the Al₂O₃ content, the better the refractoriness and erosion resistance, but the cost also increases accordingly
• Low-creep high alumina brickis suitable for high-temperature load-bearing parts above 1300℃ for long periods (such as hot blast stove domes)
• Ordinary high alumina brickis suitable for areas with relatively moderate temperature and load
• Where clay brick can meet the requirements, high alumina brick need not be selected