70 alumina fire brick, containing 70% AL2O3, is a high-quality refractory material. It is primarily made from high-alumina bauxite shaped and fired at high temperatures, giving it excellent properties such as high strength, high refractory temperature, good thermal shock resistance, and strong erosion resistance. The high alumina content enhances its refractory and corrosion-resistant properties, allowing it to maintain stable performance in extremely high temperatures and corrosive environments. This type of 70 alumina fire brick is widely used as linings for various high-temperature furnaces and other areas that need to withstand high temperatures and corrosive conditions. Its outstanding performance and broad application make it a crucial component in the field of refractory materials.
70 Alumina Fire Brick Main Applications
70 alumina fire brick is mainly used for lining high-temperature furnaces and other areas exposed to high temperatures and corrosive environments, including:
Blast Furnaces and Hot Blast Stoves: In this steelmaking equipment, high-alumina bricks can withstand high-temperature furnace gases and molten slag, protecting the furnace structure from damage.
Glass Kilns: In glass production, high-temperature kilns are crucial equipment. High-alumina bricks, used as kiln linings, can endure high temperatures and molten glass erosion, ensuring smooth glass production.
Cement Rotary Kilns: During cement production, rotary kilns face the dual challenges of high temperatures and material abrasion. High-alumina bricks provide good wear resistance and refractoriness, extending the kilnās service life.
Ceramic Kilns: In the production of ceramics, high-alumina bricks play an important role by withstanding high temperatures and kiln atmosphere erosion, ensuring the quality and efficiency of ceramic production.
70 Alumina Fire Brick Characteristics and Advantages
General-purpose High Alumina Bricks
High Strength: High-alumina bricks have high compressive and flexural strength, allowing them to withstand mechanical stress at high temperatures.
High Refractoriness: The high alumina content results in a higher refractory temperature, allowing the bricks to remain stable in higher-temperature environments.
Good Thermal Shock Resistance: High-alumina bricks can resist thermal stresses caused by temperature fluctuations, preventing cracking and spalling.
Strong Erosion Resistance: They have good resistance to erosive media such as slag and furnace gases, prolonging the furnaceās lifespan.
High Alumina Bricks Classification Standards
70 alumina fire bricks are generally classified as secondary high-alumina bricks in the refractory material classification. High-alumina bricks are graded based on their alumina (AlāOā) content, and the specific classification standards may vary slightly by country or industry. For example, in Europe, high-alumina refractory materials have an AlāOā content of at least 42%. Typically, they are divided into three grades:
- Grade I: AlāOā content > 75%
- Grade II: AlāOā content 60-75%
- Grade III: AlāOā content 48-60%
Grade I high-alumina bricks, with an AlāOā content over 75%, are the highest grade, offering exceptional refractoriness and erosion resistance. The higher the alumina content, the higher the refractory temperature. Grade I bricks can withstand temperatures above 1750Ā°C, with a softening point under load of 1510Ā°C, a bulk density of over 2.5 g/cmĀ³, high density, and stability, with each brick weighing up to 4.4 kg.
Grade II high-alumina bricks, such as 70 alumina fire bricks with an AlāOā content between 60% and 75%, offer good refractory performance and erosion resistance but are slightly inferior to Grade I bricks. Therefore, 70 alumina fire brick, as a secondary high-alumina brick, plays an important role in high-temperature kiln linings but might be less suitable for applications requiring extremely high refractory performance.
Itās important to note that the choice of refractory material depends not only on alumina content but also on factors like the operating environment, cost-effectiveness, and construction conditions. In practice, the most suitable refractory material should be selected based on specific needs.
Grade III high-alumina bricks have an AlāOā content between 48% and 60%. National standards specify that Grade II high-alumina bricks are labeled as LZ-65. For weight standards: Grade I bricks weigh 4.5 kg, Grade II bricks weigh 4.2 kg, and Grade III bricks weigh 3.9 kg.
Different High-Alumina Brick Specifications
International Standard ISO 9001
ISO 9001 is an international quality management system standard designed to help organizations improve product and service quality and meet customer needs. While it does not specifically target high-alumina bricks, many high-alumina brick manufacturers follow this standard to ensure quality control and management in production processes.
Chinese Standard
- GB/T 2988-2012 āClassification Standard for Refractory Materialsā
- Content: This standard classifies refractory materials, including high-alumina bricks, based on chemical composition, physical properties, etc.
- Key Aspects:
- Classification: Classifies refractory materials by main components (e.g., alumina content).
- Performance Requirements: Specifies requirements for refractoriness, softening temperature under load, and compressive strength at room temperature.
- Testing Methods: Defines testing methods and conditions.
- GB/T 2989-2012 āHigh-Alumina Brick Standardā
- Content: This standard is specific to high-alumina bricks and details technical requirements, production processes, and testing methods.
- Key Aspects:
- Alumina Content: Defines grades based on alumina content (e.g., 75%, 70%, 60%).
- Refractoriness: Specifies refractoriness requirements.
- Softening Temperature Under Load: Sets requirements for this temperature.
- Compressive Strength at Room Temperature: Requires bricks to meet specific compressive strength values.
- Apparent Porosity: Defines the range for apparent porosity.
American Standard
- ASTM C-27 āClassification and Specifications for Refractory Bricks and Materialsā
- Content: ASTM C-27 is a standard set by the American Society for Testing and Materials (ASTM) covering various refractory bricks and materials, including high-alumina bricks.
- Key Aspects:
- Classification: Classifies different types of refractory bricks, including high-alumina bricks.
- Performance Standards: Specifies main performance indicators like refractoriness, softening temperature under load, and compressive strength at room temperature.
- Testing Methods: Provides methods and conditions for testing refractory brick performance.
European Standard
- EN 993-1 āTesting Methods for Refractory Materialsā
- Content: EN 993-1, developed by the European Committee for Standardization (CEN), covers testing methods for refractory materials, including high-alumina bricks.
- Key Aspects:
- Testing Methods: Details methods for testing performance aspects such as refractoriness, softening temperature under load, and thermal expansion.
- Testing Conditions: Defines experimental conditions and instrument requirements.
- Data Processing: Guides how to process and interpret test results.
- Testing Methods: Details methods for testing performance aspects such as refractoriness, softening temperature under load, and thermal expansion.
These standards provide regulations for the production, testing, and application of high-alumina bricks, ensuring their performance stability and reliability in high-temperature environments.
Agrmās high-alumina bricks are manufactured in strict accordance with ISO 9001, using high-quality rotary kiln GL-70 raw materials. They feature a bulk density of over 3 g/cmĀ³, a water absorption rate of less than 5%, high sintering temperature, and low NaāO and KāO content. Additionally, they include a suitable amount of mullite to strengthen the matrix, leveraging the high-temperature volumetric effects of natural minerals. This results in products with high softening temperature under load, high-temperature flexural strength, and low thermal expansion.
These bricks are characterized by wear resistance, corrosion resistance, spall resistance, low creep, good thermal shock stability, and a service life 1.5 times longer than ordinary products.
Why Use 70 Alumina Fire Brick in High-Temperature Kiln Linings?
70 alumina fire brick is highly suitable for use in high-temperature kiln linings due to its outstanding performance in high-temperature environments.
High Refractoriness
70 alumina fire brick can endure temperatures above 1700Ā°C, ensuring that the brick does not melt or deform under high temperatures and effectively protects the kiln structure. With increased alumina content, the quantities of mullite and corundum increase while the glass phase decreases, enhancing high-temperature stability and erosion resistance. Specifically, corundum provides exceptional chemical stability and refractoriness, making the 70 alumina fire brick perform excellently at high temperatures.
Good Thermal Shock Resistance
Kilns experience frequent temperature fluctuations. 70 alumina fire brickās thermal shock resistance allows it to endure sudden temperature changes without cracking or spalling, which is crucial for maintaining the integrity of the kiln lining and extending its service life.
Strong Erosion Resistance
High-temperature kilns are often exposed to corrosive media such as chemical gases and molten slag. 70 alumina fire brick exhibits high resistance to these substances, maintaining stable performance in harsh environments. This erosion resistance prevents the bricks from being easily damaged, extending the kiln’s service life. The ability to withstand various slags and gases reduces material wear and damage to the kiln’s internal structure.
Excellent Wear Resistance
Material abrasion and friction are common in high-temperature kilns. 70 alumina fire brick, with its high hardness and wear resistance, maintains its integrity under prolonged material abrasion and friction. This wear resistance helps reduce the frequency of lining material replacement and lowers maintenance costs. The bricks can endure impacts, friction, and the kiln’s weight and pressure, ensuring the kilnās structural stability.
Wide Application
70 alumina fire brick is extensively used as lining material in various high-temperature kilns, such as blast furnaces, hot blast stoves, glass kilns, and cement rotary kilns. These applications highlight its reliability and stability in high-temperature environments.
Overall, 70 alumina fire brickās excellent refractoriness, thermal shock resistance, erosion resistance, and wear resistance make it highly suitable for kiln linings. Its use in high-temperature kilns effectively protects the kiln structure, extends its lifespan, and reduces maintenance costs.
