Graphite Brick
Graphite bricks are graphite products primarily made from natural or synthetic graphite, considered a specialized type of graphite block. They are commonly used as linings and insulation layers in industrial furnaces, high-temperature furnaces, and heat treatment equipment. Graphite, a highly crystalline carbon material, possesses excellent thermal conductivity and chemical stability. This allows graphite bricks to maintain structural stability and durability at very high temperatures (typically exceeding 2500°C), making them an ideal choice for many industrial furnaces and high-temperature processing equipment.
The design and manufacturing of graphite bricks need to consider the furnace structure, temperature gradients, and the nature of the materials being processed. AGRM can produce customized shapes and sizes of graphite bricks to meet specific requirements.
Graphite Brick Types
As a leading graphite electrode supplier, AGRM has nearly 20 years of experience in customizing graphite products, ensuring product dimensions within drawing tolerances. Please contact our engineers for more personalized solutions if you have any requirements.
Standard rectangular or square bricks used for large-area paving.
Special-shaped bricks such as corner bricks and curved bricks used for specific parts or areas with special shapes.
Characteristics of AGRM Graphite Bricks
The performance of blast furnace hearth refractory materials is one of the key factors influencing the lifespan of blast furnaces. AGRM continuously improves the process technology of blast furnace hearth refractory materials, enhances the performance and structure of graphite bricks, and utilizes high thermal conductivity, high purity, and microporous hot-pressed graphite bricks to overcome damage to the hearth caused by factors such as alkali corrosion, carbon accumulation, and molten iron infiltration.
- Extremely high refractoriness
Volatilization only occurs at very high temperatures (>3000℃), making it suitable for the working environment of blast furnaces.
- Very high load softening point
This applies to high-quality graphite bricks with sufficiently low ash content, a point that AGRM ensures.
- Corrosion resistance
It can resist erosion from various acids, alkalis, salts, and organic solvents.
- High compressive strength
Compressive strength can reach 250-500 kg/cm2.
- Excellent slag resistance
Except for slag with high FeO content, no other slag can cause corrosion.
- High wear resistance
Superior to common clay bricks.
- Low thermal expansion coefficient
This is one of the advantages of graphite bricks over other refractory materials. Rapid cooling at high temperatures does not cause cracking, hence graphite bricks are widely used in furnace bottom construction.
Graphite Brick Specifications
| Item | Unit | Standard | Test Results | |
| Bulk density | g/cm3 | 1.7 | 1.75 | |
| Ash | % | <=14 | 12 | |
| Open porosity | % | <= | 16 | |
| Compressive strength | MPa | >=35 | 40 | |
| Reheating change rate | % | ±0.1 | 0 | |
| Bending strength | MPa | >=12 | 15 | |
| CMOR(Corrosion index hotmetal) | % | <=28 | 27 | |
| Oxidation rate | % | <=12 | 11 | |
| Air Permeability porosity | mDa | <=9 | 5 | |
| Coefficient of heat conductivity | Normal temperature | W/m.K | 12 | 13 |
| 300ºC | 14 | 15 | ||
| 600ºC | 15 | 16 | ||
| Alkali Resistance | U, LC ,C | U | U |
Why AGRM?
Comprehensive Service System
24/7 sincere service, quick response, valuable advice, and thoughtful after-sales service. We provide dedicated transportation for factory and laboratory visits, with detailed explanations of our products. Our professional engineering team is available to guide installation and testing upon customer request.
Customized Solutions
AGRM, as a specialized producer of graphite products, has accumulated rich experience in the industrial kiln applications of carbonaceous refractory materials. We provide customers with customized, one-stop graphite product solutions.
Application of Graphite Bricks
Graphite bricks are widely used in the metallurgical industry, with extensive applications in blast furnaces. Many blast furnace hearths and linings are constructed using graphite bricks. In recent years, their use has expanded to include the lower parts of furnace hearths and bodies, which can increase blast furnace operation continuity and extend lifespan.
Furthermore, graphite bricks are also utilized in acid pickling tanks and electroplating tanks in the electroplating industry, dissolution tanks in the paper industry, reaction tanks and storage tanks in the chemical industry, and high-pressure vessels in the petrochemical industry.
Process Control of Graphite Bricks
Process Route Determination
Coking – Calcination – Crushing (Grinding) – Blending – Mixing (with binder asphalt addition) – Extrusion molding – Roasting – First impregnation – Second roasting – Second impregnation – Third roasting – Graphitization – Processing.
Process Control
- 1. Control of Calcination Quality
The calcination temperature is controlled between 1250~1300℃, and the discharge rate is adjusted appropriately to maintain the post-calcination coke true density at around 2.07 g/cm³. The coke after calcination has a moderate activation point, stable adsorption capacity, requires less asphalt during the forming process, results in high product strength, and exhibits good performance.
- If the calcination temperature is too low, the coke undergoes secondary shrinkage after calcination during subsequent graphitization heat treatment, leading to structural cracks and increased product consumption during use.
- If the calcination temperature is too high, the activation point of the coke after calcination increases, enhancing adsorption capacity. This leads to increased binder usage, and during later sintering heat treatment, the exclusion of light asphalt fractions increases the product’s porosity and defects, accelerating product consumption during use.
- 2. Extended Mixing Time and Improved Temperature Control During Mixing
In recent years, with the deep processing of coal tar products, the properties of coal tar pitch have changed: the softening point has increased, asphalt viscosity has become higher, and the plasticity range has decreased. Through analysis of the viscosity-temperature curve of asphalt, it has been determined that increasing the asphalt infiltration temperature and mixing temperature to enhance asphalt’s penetration effect on coke, ensure that the mixing power curve remains unchanged, and ensure that the paste has good plasticity, thereby ensuring the structure of graphite bricks.
Simultaneously, adopting a high-temperature feeding system reduces the plasticity differences of each batch of paste. Lowering compacting pressure reduces internal structural differences. Extending the press’s pre-pressing time increases product density.
- 3. Multiple Impregnation and Calcination Process
To ensure a lower apparent porosity of the product and meet comprehensive performance indicators, we have introduced two additional impregnation and calcination cycles to fill the pores and reinforce the product. Products must be thoroughly cleaned after calcination and before impregnation, and they require staggered basket loading to ensure gaps for impregnation.
- 4. Graphitization using small core furnaces, with graphitization temperatures reaching above 2900~3000℃. The higher the graphitization heat treatment temperature, the higher the starting oxidation temperature of the graphite material, resulting in stronger oxidation resistance.
- 5. Due to various shapes of finished products, high precision and large quantities are required in processing. The processing method involves sawing first, planing second, and milling last. On the secondary precision platform, the width and height tolerances of graphite bricks are controlled within ±0.5mm.
