Introduction
High alumina brick is a refractory material composed primarily of Al₂O₃. Classified as an aluminosilicate refractory product with an aluminum oxide (Al₂O₃) content exceeding 48%, it exhibits near-neutral properties and resists erosion from both acidic and alkaline slags. However, its resistance to alkaline slag is weaker due to the presence of SiO₂. Manufactured from bauxite or other high-alumina raw materials through molding and calcination, it features high thermal stability and a refractoriness above 1770°C.
Primarily used for lining high-temperature kilns such as blast furnaces, hot blast stoves, electric furnace roofs, reverberatory furnaces, and rotary kilns, high alumina bricks also serve as regenerative checker bricks in open-hearth furnaces, stoppers for pouring systems, and nozzle bricks.
Advantage
High Refractoriness
High Load Softening Temperature
Products with high Al₂O₃ content and low impurity levels form less fusible vitreous phase, resulting in a higher load softening temperature (1420–1530°C) than clay bricks. However, due to the absence of a continuous mullite crystal network, their load softening temperature is still lower than that of silica bricks.
Strong Slag Resistance
With high Al₂O₃ content, these bricks behave as near-neutral refractories and resist both acidic and alkaline slag erosion. However, their resistance to alkaline slag is relatively weaker due to the presence of SiO₂.
High Mechanical Strength at Elevated Temperatures
High alumina bricks maintain significant strength at high temperatures, withstanding furnace load and mechanical impact during charging and discharging, thereby ensuring the stability of the furnace structure.
Poor Thermal Shock Resistance
The coexistence of corundum and mullite creates thermal stress due to differences in their linear expansion coefficients. This mismatch leads to stress concentration during temperature fluctuations, limiting thermal shock resistance to only 3–5 water-cooling cycles.
Low Refiring Line Change
When fired at adequate temperatures and durations, high alumina bricks exhibit stable volume and minimal refiring shrinkage. However, insufficient firing may cause residual shrinkage due to internal recrystallization.
Raw Materials & Classification
High alumina bricks are primarily composed of alumina (Al₂O₃) and silicon dioxide (SiO₂), and they are classified based on Al₂O₃ content:
Grade I: Al₂O₃ > 75%
Grade II: Al₂O₃ = 60–65%
Grade III: Al₂O₃ = 55–60%
Bricks with Al₂O₃ content exceeding 85% are referred to as corundum bricks. In general, higher alumina content equates to better performance.
Physical and Chemical Specifications
| Grade / Specifications |
LZ-80 |
LZ-75 |
LZ-70 |
LZ-65 |
LZ-60 |
LZ-55 |
LZ-48 |
|
|
Al2O3 |
≥ |
80 |
75 |
70 |
65 |
60 |
55 |
48 |
|
Apparent Porosity (%) |
≤ |
21 |
24 |
24 |
24 |
26 |
22 |
22 |
|
Cold Crushing Strength (MPa) |
≥ |
70 |
60 |
55 |
50 |
45 |
45 |
40 |
|
Refractoriness under Load ºC @0.2MPa |
≥ |
1530 |
1520 |
1510 |
1500 |
1430 |
1450 |
1420 |
|
Reheating Linear Change % |
1500 ºC x 2hrs -0.4-0.2 |
1450 ºC x 2hrs -0.4-0.1 |
||||||
process
Raw Material Preparation:
Main raw materials include high-alumina bauxite, silica minerals, and synthetic materials. High-alumina bauxite must be calcined in rotary or vertical kilns at 1500–1700°C.
Crushing and Grading:
Materials are crushed, and clinker is sorted, screened, and de-ironed to ensure purity and proper particle size distribution.
Mixing:
The processed raw materials are mixed with appropriate binders to form a clay with suitable plasticity.
Molding:
The clay is shaped into bricks via press or extrusion molding methods.
Drying:
The shaped bricks are dried to remove moisture and increase green strength.
Firing:
Bricks are fired in tunnel or other high-temperature kilns at 1500–1600°C to achieve the desired performance metrics.
applianction
1. Metallurgical Industry
Used in key components of furnaces such as:
Electric Arc Furnaces (EAF):
Applied in furnace covers and walls to resist high-temperature arcs and slag erosion.
Blast Furnaces:
Furnace Body: Resists mechanical wear and gas erosion.
Furnace Bottom: Withstands molten iron penetration and erosion.
Hot Blast Stoves:
Used in arches and walls to endure thermal cycling and high-temperature air flow, ensuring stable performance.
2. Building Materials Industry
Cement Kilns:
Installed in transition and firing zones where they resist high heat and alkaline erosion.
Glass Kilns:
Used in pool walls and combustion chambers to resist molten glass and flame radiation.
3. Power Industry
In thermal power boilers, they serve as linings for furnaces and flues, resisting high-temperature gases and abrasion. Also used in waste incineration plants due to their resistance to corrosive gases.
4. Chemical Industry
Used in gasifiers and ammonia conversion furnaces for high-temperature reaction zones, providing structural integrity and thermal insulation.
5. Other Applications
Also used as checker bricks in open-hearth furnaces, pouring stoppers, and nozzle bricks due to their high-temperature stability and resistance to wear.
Purchase ZINFON refractory Bricks at Reasonable Prices
The price of refractory bricks is a known key factor influencing customers' purchasing decisions. Therefore, we offer affordable refractory bricks for sale. Here are several reasons why ZINFON provides refractory bricks at competitive prices:
Factory price
By collaborating with ZINFON, we ensure that customers enjoy the ex-factory price of refractory bricks, reducing costs from middlemen or distributors. This allows customers to obtain the most cost-effective pricing directly from the source.
Low raw material cost
ZINFON is surrounded by abundant mineral resources. With these high-quality materials, customers can obtain products that are both affordable and excellent in performance.
Mass production
ZINFON possesses advanced production equipment and technologies, enabling the factory to achieve economies of scale and reduce unit production costs. Meanwhile, it ensures a continuous supply of high-quality products at preferential prices.
It is worth noting that while price is an important factor, it should not be the sole determinant of your purchasing decision. When buying refractory bricks from ZINFON, quality, reliability, and technical support are equally important considerations.
By choosing ZINFON as your supplier, you can access high-quality refractory bricks, a wide range of other refractory materials, and comprehensive support. Contact ZINFON Refractories immediately to discuss your specific requirements and obtain customized solutions!
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