High alumina refractory bricks, with an alumina content over 48%, are neutral refractory materials designed for high-temperature industrial applications. They offer outstanding dimensional stability, refractoriness above 1700 °C, and excellent resistance to corrosion and slag. Ideal for thermal zones where high strength and chemical resistance are essential, they are widely used in hot blast stoves, heating furnaces, incinerators, and aluminum smelting systems.
Table 1
|
Project |
LZ-80 |
LZ-75 |
LZ-65 |
LZ-55 |
LZ-48 |
|
|
Al2O3 % ≥ |
80 |
75 |
65 |
55 |
48 |
|
|
Apparent Porosity % ≤ |
22 |
23 |
23 |
22 |
22 |
|
|
Room Temperature Compressive Strength MPa ≥ |
55 |
50 |
45 |
40 |
35 |
|
|
0.2MPa Load Softening Start Temperature ℃ ≥ |
1530 |
1520 |
1500 |
1450 |
1420 |
|
|
Heating Permanent Line Change % |
1500℃×2h |
+0.1～-0.4 |
-- |
|||
|
1450℃×2h |
+0.1～-0.4 |
|||||
Table 2
|
Product Indicators |
Unit |
High Alumina Refractory Bricks |
Phosphate-Bonded High Alumina Bricks |
Anti-stripping High Alumina Bricks |
||||||||
|
LZ-48 |
LZ-55 |
LZ-65 |
LZ-70 |
LZ-75 |
LZ-80 |
P |
PA |
KBL-70 |
KBL-70 |
|||
|
Al2O3 ≥ |
% |
48 |
55 |
65 |
70 |
75 |
80 |
75 |
77 |
70 |
70 |
|
|
Fe2O3 ≤ |
% |
- |
- |
- |
- |
- |
- |
3.2 |
3.2 |
- |
- |
|
|
ZrO2 ≥ |
% |
- |
- |
- |
- |
- |
- |
- |
- |
6 |
- |
|
|
0.2MPaLoad Softening Starting Temperature |
℃ |
1420 |
|1450 |
1500 |
1510 |
1520 |
1530 |
1350 |
1300 |
1470 |
1470 |
|
|
Reheating Linear Change Rate |
1500℃×2h |
% |
- |
- |
- |
- |
0.2-0.4 |
0.2-0.4 |
- |
- |
- |
- |
|
1450℃×2h |
% |
0.1-0.4 |
0.1-0.4 |
0.1-0.4 |
0.1-0.4 |
- |
- |
- |
- |
0.1-0.2 |
0.1-0.2 |
|
|
Apparent Porosity ≤ |
% |
22 |
22 |
24 |
24 |
24 |
21 |
- |
- |
22 |
20 |
|
|
Room Temperature Compressive Strength |
MPa |
40 |
45 |
50 |
55 |
60 |
70 |
70 |
75 |
60 |
60 |
|
|
Bulk Density ≥ |
g/cm3 |
23 |
2.35 |
2.4 |
2.5 |
2.6 |
2.7 |
2.7 |
2.75 |
2.55 |
2.55 |
|
|
|
Grade ⅠHigh Alumina Refractory Bricks: Al₂O₃ content ≥75%
|
|
|
Grade II High Alumina Refractory Bricks: Al2O3 content 60%–75%
|
|
|
Grade III High Alumina Refractory Bricks: Al₂O₃ content 48%～60%
|
|
1.Outstanding high-temperature performance and structural stability: Featuring ≥48% Al₂O₃, the material's rich mullite and corundum crystalline phases maintain a stable structure even at temperatures exceeding 1700 °C.
|
2.High slag resistance and chemical stability: With excellent resistance to acidic and neutral slags, the material maintains a dense, stable structure even in environments containing SiO₂, Fe₂O₃, or alkaline dust. |
3.Excellent strength and wear resistance: Designed for areas exposed to airflow erosion and material impact, the bricks feature a dense, hard surface achieved through optimized particle size distribution and high-temperature firing, resulting in wear resistance far superior to ordinary clay bricks. |
|
4.Outstanding thermal shock resistance: High alumina refractory bricks resist rapid temperature fluctuations, minimizing cracking. Thanks to the mullite crystalline phase with a low coefficient of thermal expansion, the material preserves its structural and phase integrity even under repeated thermal cycles. |
5.High-density, low-porosity design: Optimized granulation and firing processes produce a dense, low-porosity structure that improves erosion resistance, reduces heat loss, and delivers substantial energy savings. |
6.Flexible and customizable shapes: The material can be produced in irregular or custom shapes to fit different furnace designs. Using a modern automated shaping production line, it can be made into arc-shaped bricks, wedge-shaped bricks, burner bricks, furnace wall bricks, and protective plate bricks. |
High alumina refractory bricks, containing over 46% Al₂O₃, are used in glass furnaces in small quantities, representing only about 1% of total refractory materials. These bricks are mainly utilized for specialized refractory components, including stirring paddles, uniform mixing cylinders, and punches, installed in working tank walls, material channels, and feeding systems.
I. Composition
Raw Materials
Raw materials for high alumina refractory bricks are classified into two main categories: natural and artificially synthesized.
Natural raw materials include:
Bayerite (Al(OH)₃) and gibbsite (Al₂O₃·3H₂O)
Sillimanite (Al₂O₃·SiO₂, ~63% Al₂O₃, 37% SiO₂) and its isomers kyanite and andalusite
Artificially synthesized materials consist of synthetic minerals produced by chemical methods, such as aluminum hydroxide, aluminum hydride, selected kyanite, and clay minerals. Typical synthetic minerals include:
Mullite (3Al₂O₃·2SiO₂), synthesized via sintering or electrofusion methods
II. Chemical Composition
The chemical composition of high alumina refractory bricks varies depending on the raw materials used.
Al₂O₃ content ranges from 46% to nearly 100%, while SiO₂ content ranges from 0.5% to 47%.
III. Crystal Phase Composition
The crystalline phase composition of high alumina refractory bricks varies with Al₂O₃ content.
The bricks primarily consist of sillimanite, mullite, and corundum, with minor amounts of quartz and cristobalite.
Additionally, they generally contain a glassy phase composed of Al₂O₃, SiO₂, and other oxides.
Q1. What is the service temperature range of high alumina refractory bricks?
A：They can typically operate continuously at 1400–1700 ℃, while high-grade products can withstand temperatures above 1750 ℃.
Q2. Are they suitable for highly corrosive environments such as molten aluminum and molten steel?
A：Yes. Their mullite and corundum structure provides excellent impermeability, and they can be used together with corundum bricks or non-wetting aluminum castables.
Q3. Can they be combined with castable or lightweight bricks?
A：Yes. They are commonly combined with lightweight castables, lightweight mullite bricks, and refractory precast components to construct energy-saving composite structures.
Q4. Do you support custom-shaped bricks or tiles?
A：Yes. Various irregularly shaped bricks, curved bricks, wedge-shaped bricks, and prefabricated components can be manufactured according to drawings.
Q5. What is their typical service life?
A：Service life is typically 20–30% longer than ordinary refractory materials, depending on temperature, furnace gas composition, and maintenance practices.
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