Introduction
Lightweight high alumina bricks, also known as high alumina insulating bricks, contain over 48% alumina and primarily consist of mullite, glassy phases, or corundum. With a bulk density of 0.4–1.35 g/cm³, porosity of 66–73%, and compressive strength of 1–8 MPa, they are typically manufactured by finely grinding high-alumina bauxite clinker with a small amount of clay, forming via gas generation or foaming methods, and firing at 1,300–1,500°C. These bricks serve as kiln linings and insulation layers, especially for lightweight high alumina brick applications.
Lightweight high alumina bricks are suitable for kiln linings and insulation in areas not exposed to severe erosion or abrasion from high-temperature molten materials. When in direct contact with flames, the surface temperature should not exceed 1,350°C.
Advantage
Low Density
Bulk density typically ranges from 0.8 to 1.6 g/cm³ (common high alumina bricks: 2.3–2.7 g/cm³), reducing weight by 30%–70%. This significantly decreases the structural load on furnaces, especially for ceilings and lightweight retrofits.
Superior thermal insulation
Room-temperature thermal conductivity is 0.15–0.35 W/(m·K) (only 1/4–1/3 that of dense high alumina bricks). At 1,000°C, thermal conductivity is ≤0.6 W/(m·K), lowering furnace outer wall temperatures by 50–80°C and enhancing energy efficiency by 15%–30%.
High refractoriness
With Al₂O₃ content between 48%–75%, the refractoriness ranges from 1,700–1,790°C. The long-term service temperature is 1,300–1,500°C (depending on Al₂O₃ content), outperforming lightweight clay bricks (≤1,350°C) in higher-temperature applications such as the high-temperature zones of metallurgical heating furnaces and ceramic sintering kilns.
High-temperature stability
Sintering forms a mullite (3Al₂O₃·2SiO₂) and corundum (α-Al₂O₃) crystal skeleton. The shrinkage rate is <1% at 1,400°C, and the creep resistance (creep rate <0.5% at 1,400°C for 24h) significantly exceeds that of lightweight clay bricks.
Excellent thermal shock resistance
High porosity (45%–65%) buffers thermal stress. The low thermal expansion coefficient (5–7 × 10⁻⁶/°C) enables the brick to withstand ≥15 water-cooling cycles at 1,100°C without cracking, making it suitable for frequently started/stopped kilns (e.g., heat treatment furnaces, reversing sections of glass kilns).
Mechanical strength
Room-temperature compressive strength is 8–25 MPa, sufficient for non-load-bearing structures. Strength retention at 1,000°C is over 60%, with better resistance to mechanical scouring than lightweight clay bricks.
Acid resistance
Exhibits strong resistance to erosion by glass melts and acidic furnace gases (e.g., SO₂, Cl₂), making it suitable for glass kiln regenerators and chemical reactor linings.
Alkaline resistance
When the Al₂O₃ content exceeds 60%, resistance to CaO/MgO-based alkaline slags improves significantly, although direct contact with high-alkalinity slags should be avoided.
Metal/slag penetration resistance
Predominantly closed pores (closed pore rate >50%) reduce penetration by molten metals (e.g., iron, copper), making these bricks ideal for insulating layers in non-ferrous metal smelting furnaces.
Zinfon Refractory Technology Co.,Ltd.
We provide one-stop services from technical consultation to design, production, and after-sales support.
Raw Materials
Bauxite clinker with small amounts of clay
Physical and Chemical Specifications
|
Item |
Specification |
|||||
|
LG-1.2 |
LG-1.0 |
LG-0.8 |
LG-0.7 |
LG-0.6 |
LG-0.5 |
|
|
Al2O3 % |
≥48 |
|||||
|
Fe2O3 % |
≤2 |
|||||
|
Bulk Density, g/cm3 |
≤1.2 |
≤1.0 |
≤0.8 |
≤0.7 |
≤0.6 |
≤0.5 |
|
CCS, MPa |
≥4.5 |
≥3.5 |
≥2.5 |
≥2.2 |
≥1.6 |
≥1.2 |
|
PLC, % |
1400℃×12h ≤-2 |
1350℃×12h ≤-2 |
1250℃×12h ≤-2 |
|||
|
Thermal Conductivity, W/(m·K) 350±25℃ |
≤0.55 |
≤0.50 |
≤0.35 |
≤0.30 |
≤0.25 |
≤0.20 |
Process
Raw Material Preparation → Ingredient Mixing → Molding → Drying → Firing → Post-treatment → Quality Inspection → Packaging and Storage
Firing Regime
Temperature Rise Stage
300–600°C: Slowly increase temperature (50–80°C/h) to prevent violent decomposition of the pore-forming agent, which could cause cracking.
1,000–1,200°C: Hold for 2–4 hours to promote mullite phase formation.
Maximum Temperature
1,400–1,550°C (depending on Al₂O₃ content), with a holding time of 4–8 hours to ensure complete sintering.
Cooling Stage
Apply rapid cooling (100–150°C/h) above 800°C to avoid volume expansion from secondary mullitization.
Applications
Lightweight high alumina bricks share similar application scenarios with lightweight clay bricks, including:
· Heating and heat treatment furnaces
· Annealing and soaking pits
· Iron pretreatment equipment
· Glass kilns
· Ceramic sintering kilns
· Cement industry applications
· Reactors and heating furnaces
· Refractory chimneys and pipelines
· Fertilizer production equipment
· Boilers and incinerators
· Nuclear power auxiliary equipment
· Kiln maintenance and temporary insulation
Lightweight High Alumina Bricks vs. Lightweight Clay Bricks
| Comparison Dimension | Lightweight High Alumina Bricks | Lightweight Clay Bricks |
|---|---|---|
| Main Raw Materials | High alumina bauxite, industrial alumina; Al₂O₃ ≥ 48% | Clay, refractory clay; Al₂O₃ typically < 30% |
| Mineral Composition | Mullite (3Al₂O₃·2SiO₂), corundum (α-Al₂O₃) | Mullite, glassy phases, trace quartz |
Material and Composition Differences
| Indicator | Lightweight High Alumina Bricks | Lightweight Clay Bricks |
|---|---|---|
| Fire resistance | 1,770–1,830°C | 1,670–1,730°C |
| Max operating temp. | 1,200–1,400°C (depends on Al₂O₃ content) | 1,000–1,200°C |
| Bulk density | 0.6–1.0 g/cm³ | 0.4–0.8 g/cm³ |
| Thermal conductivity | 0.15–0.3 W/(m·K) @ 200°C | 0.1–0.25 W/(m·K) @ 200°C |
| Compressive strength | 3–8 MPa | 2–6 MPa |
Performance Indicators
| Area | Lightweight High Alumina Bricks | Lightweight Clay Bricks |
|---|---|---|
| High-temperature kilns | Metallurgical heating furnaces, glass kilns (1,200–1,400°C zones) | Annealing furnaces, drying kilns (≤1,200°C) |
| Chemical & Energy | Petrochemical cracking furnaces, high-temp zones in gasifiers | Fertilizer equipment, reactor insulation |
| Erosion resistance | Chimneys exposed to acidic/alkaline gases (e.g., SO₂, NOx) | Boiler flues with non-corrosive gases |
| Special conditions | Areas with thermal loads or minor mechanical stress | Low-temp, load-free insulation (e.g., kiln exteriors) |
Application Areas
Selection Guidelines
Choose lightweight high alumina bricks when:
Working temperature > 1,200°C
Exposure to chemical erosion (e.g., flue gases, slag)
Mechanical or thermal stress exists (e.g., kiln vaults, high-temp zones)
Choose lightweight clay bricks when:
Insulation required at ≤1,000°C
No corrosive media present
No mechanical load required (e.g., outer insulation layers)
Why chooes us?
01/Customized dimensions and shapes
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02/Delivery cycle and logistics
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Sea freight, land freight. Determine the mode of transportation according to the needs
About 30 days, customized products delivery time depends on the actual situation.
03/Customized packaging
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Customize your brand
Logo customization, custom fonts, taglines and messages for packaging, signage, websites or printed materials.
Take your brand to the next level, contact us today to discuss your project!
04/Purchase ZINFON refractory Bricks at Reasonable Prices
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We recognize that pricing is a critical factor in our customers' purchasing decisions. Leveraging our proximity to abundant mineral resources and advanced manufacturing technologies, we offer competitive pricing without compromising on quality. Our strategic location minimizes raw material costs, while economies of scale achieved through state-of-the-art processes further reduce unit production expenses.
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!
7*24 hours online response
Provide professional after-sales protection
Our address
Qinghua Management Dist., Dashiqiao City, Yingkou City, Liaoning, China
Phone Number
+8613700131695
+8618540210631
info@zinfon-refractory.com
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