High alumina bricks are neutral refractory materials with an alumina content of over 48%. They are manufactured from bauxite or other high-alumina raw materials through forming and high-temperature firing.
According to their alumina content, ZINFON high alumina bricks are classified into three grades:
Grade I: Al₂O₃ > 75%;
Grade II: Al₂O₃ ranging from 60% to 75%;
Grade III: Al₂O₃ ranging from 48% to 60%.
Featuring excellent thermal stability and superior slag resistance, they are primarily used for lining blast furnaces, hot blast stoves, electric furnace roofs, cupolas, reverberatory furnaces, and rotary kilns.
In addition, high alumina bricks are widely used as regenerator checker bricks for open-hearth furnaces, as well as stopper heads and nozzle bricks used in casting systems.
Physical and Chemical Specifications
| Item | Index | ||||
| LZ-75 | LZ-65 | LZ-55 | LZ-48 | ||
| Al₂O₃ content, %, min | 75 | 65 | 55 | 48 | |
| Refractoriness, ℃ | min | 1790 | 1770 | 1750 | |
| Initial refractoriness-under-load temperature at 0.20 MPa, ℃ | min | 1520 | 1500 | 1470 | 1420 |
| Permanent linear change on reheating, % | 1500℃, 2h |
0.01 -0.4 |
- | ||
| 1450℃, 2h | - | -0.4 | |||
| Apparent porosity, %, max | 23 | 22 | |||
| Cold crushing strength, MPa, min | 53.9 | 49.0 | 44.1 | 39.2 | |
Properties & Service Conditions for ZINFON's Full Range of High Alumina Bricks
Grade I: Al₂O₃ > 75%. Features a dense structure with low impurity content, outstanding high-temperature strength, and excellent slag resistance and penetration resistance.
Suitable for high-temperature service conditions ranging from 1400°C to 1550°C. Mainly used in high-temperature zones, combustion zones, areas subject to material erosion in kilns, and the core linings of auxiliary metallurgical furnaces.
Grade II: Al₂O₃ ranging from 60% to 75%. Features well-balanced overall properties, superior high-temperature resistance, erosion resistance, and thermal shock stability, making it the most widely used grade with broad industrial applicability.
Suitable for medium-to-high-temperature service conditions ranging from 1200°C to 1400°C. Widely used in heating furnaces, heat-treatment furnaces, low-temperature sections of rotary kilns, and general lining applications in heat-storage equipment.
Grade III: Al₂O₃ ranging from 48% to 60%. Basic high alumina bricks with higher refractoriness and better structural performance than fire clay bricks, as well as good thermal stability.
Suitable for medium-temperature service conditions below 1200°C. Commonly used for boiler linings, low-temperature flues, thermal insulation layers of kilns, and auxiliary insulating masonry. They are ideal for general service conditions involving low loads and mild erosion and abrasion.
Dimensions of ZINFON High Alumina Bricks
ZINFON supplies refractory bricks in a wide range of standard sizes.
Straight Bricks: 230 × 114 × 65 mm, 230 × 114 × 32 mm, 230 × 65 × 55 mm, 230 × 230 × 38 mm, etc.
Wedge Bricks: 230 × 114 × 65/45 mm, 230 × 114 × 65/55 mm, 230 × 114 × 50/35 mm
Arch Spring Bricks, Key Bricks, Curved Bricks, and Anchor Bricks (Hanging Bricks): Custom according to customer drawings; standard lengths available: 230 mm / 300 mm / 345 mm
Blast Furnace Checker Bricks (Multi-hole Honeycomb Bricks): 150 × 150 × 100 mm, 300 × 300 × 150 mm
Large Precast Blocks: 400 × 200 × 100 mm, 500 × 250 × 120 mm (for large smelting furnaces in export projects)
Production Process of ZINFON High Alumina Bricks
1. Raw Material Inspection & Pretreatment
We use calcined bauxite clinker as the main raw material, with bonding clay and mineralizers as auxiliary materials. All incoming raw materials are sampled and analyzed for Al₂O₃, Fe₂O₃, TiO₂, and other impurity contents. The materials are sorted, subjected to iron removal, and screened before being stored separately according to grade.
The raw materials are crushed and ground using jaw crushers, wheel mills, and ball mills, then screened into coarse, medium, and fine fractions to optimize particle gradation and achieve high compactness.
2. Automatic Precision Batching
Formulations are customized according to the target brick grade. A fully automatic weighing system accurately proportions bauxite aggregates, fine powders, bonding clay, and additives. We strictly control the minimum Al₂O₃ content and impurity limits to ensure the required refractoriness and refractoriness under load.
3. Intensive Mixing & Aging
The mixed materials are fed into wheel pan mixers and blended with a measured amount of water for 15–30 minutes. The prepared batch is then sealed and aged for more than 24 hours to ensure uniform moisture distribution, improve plasticity, and prevent lamination and cracking during molding.
4. High-Pressure Molding
Standard straight bricks and wedge bricks: Formed using automatic hydraulic presses with capacities of 500–1200 tons under molding pressures of 80–150 MPa.
Special-shaped bricks (anchor bricks, arch spring bricks, checker bricks, and curved key bricks): Pressed using customized multi-layer molds, while large precast blocks are produced through vibration molding.
Each green brick is inspected for dimensional accuracy and bulk density. Defective green bricks with chipping, lamination, or cracking are rejected.
Contact me to get a quote for custom products.
5. Temperature-Controlled Drying
Green bricks are conveyed to tunnel dryers and dried at staged temperatures of 80–120°C for gradual moisture removal. Temperature and humidity are strictly controlled to prevent cracking caused by rapid moisture loss. The moisture content is reduced to ≤2% before firing.
6. High-Temperature Tunnel Kiln Firing
The firing temperature varies according to the brick grade:
Grade I: Sintered at 1520–1600°C with a soaking period;
Grade II: 1480–1520°C;
Grade III: 1430–1480°C.
Precise control of kiln temperature and atmosphere ensures complete sintering and controlled permanent linear change. After firing, the bricks are cooled and discharged.
7. Full Physical & Chemical Inspection of Finished Products
Samples from every batch are tested in accordance with GB standards, including Al₂O₃ content, refractoriness, refractoriness under load (0.2 MPa), permanent linear change on reheating, apparent porosity, and cold crushing strength. Thermal shock resistance and slag resistance tests are also conducted upon request. Non-conforming products are separated for rework.
8. Sorting, Packing & Delivery
Qualified bricks with flawless appearance are manually sorted and packed into neutral cartons. They are then placed on fumigated, shrink-wrapped pallets and labeled with grade and size information, ready for container shipment.
How to Select Suitable High Alumina Bricks for Kilns
Selection Based on Kiln Operating Zones
Core High-Temperature Zones of Kilns
Areas subjected to intense flame erosion and severe chemical attack, such as hot blast stove crowns, electric furnace roofs, and rotary kiln firing zones.
Grade I high alumina bricks with superior performance are recommended for these areas, as they help extend service life and reduce the risk of kiln shutdowns.
Critical Medium-to-High-Temperature Areas
Locations exposed to continuous high heat loads, including main boiler bodies and the upper sections of hot blast stove regenerators. Thermal stress and chemical corrosion are significant but less severe than in core high-temperature zones.
Grade II high alumina bricks provide reliable lining protection while reducing unnecessary material costs, making them a cost-effective and well-balanced choice.
Conventional Low-Temperature Insulation Areas
Areas with relatively mild operating conditions, including portions of boiler linings, flues, and peripheral thermal insulation layers of kilns.
Grade III high alumina bricks fully satisfy the service requirements of these applications.
Packing of High Alumina Bricks
The standard export packing forms for ZINFON high alumina bricks are as follows:
Standard IPPC fumigated wooden pallets, fully sealed and waterproof with stretch film, integrally reinforced by plastic strapping. Neat and sturdy stacking, moisture-proof and impact-resistant, suitable for sea export worldwide.
Customized packaging is also available in accordance with client requirements and national import standards.Contact me for a detailed quotation.
Hot Tags: high alumina brick, China high alumina brick manufacturers, suppliers, factory, alumina insulation, high alumina refractory bricks, heatproof refractory alumina slab for industry, Andalusite Brick, heat resistant refractory alumina tile for different industries, Refractory for Electric Arc Furnace