The Application and Production Process of High-Aluminum Refractory Materials
What are high-aluminum refractory bricks? Experts from Yaozhong Refractories provide detailed answers: Refractory experts have proven through the production of high-aluminum refractory bricks that strictly selecting and grading high-aluminum clinker before crushing, and storing it by grade, as well as adopting a method of fine grinding with bauxite clinker and bonding clay, can improve product quality.
What are high-aluminum refractory bricks? Experts from Yaozhong Refractories provide specific answers: High-aluminum refractory bricks are aluminum-silicate refractory products with an aluminum oxide (Al2O3) content exceeding 48%. If the Al2O3 content exceeds 90%, they are called corundum bricks. Due to cost differences, standards in various countries are not entirely consistent. For example, European countries set the lower limit for high-aluminum refractory materials at 42% Al2O3. In China, high-aluminum bricks are divided into three grades based on their Al2O3 content: Grade One – Al2O3 content >75%; Grade Two – Al2O3 content between 60-75%; Grade Three – Al2O3 content between 48-60%.
A neutral refractory material with an Al2O3 content over 48%, made from bauxite or other raw materials with high Al2O3 content through molding and calcination. It has high thermal stability with a fire resistance above 1770°C and good slag resistance. Used for lining steelmaking electric furnaces, glass melting furnaces, cement rotary kilns, etc.
High-load softening, low-creep high-aluminum bricks are advanced refractory materials made primarily from premium-grade bauxite, electrically fused corundum, and electrically fused mullite. This product features minimal high-temperature creep, strong corrosion resistance, and excellent thermal shock stability, making it suitable for large and medium-sized hot blast stoves. It has successfully paved the way for the domestic production of high-quality, high-grade imported refractory materials required for new types of hot blast stoves in China and has been included in the national-level "Spark Program" project.
Raw Materials:
Based on cost conditions and product requirements, the following types of raw materials can be used: Hydrated alumina minerals (such as gibbsite, boehmite, etc.) mainly composed of high-aluminum bauxite; sillimanite group minerals (including kyanite, sillimanite, andalusite, etc.); synthetic materials such as industrial alumina, synthetic mullite, and electrically fused corundum. China is rich in high-quality bauxite resources, mainly distributed in Shanxi, Henan, Hebei, Guizhou, Shandong, and other places. The produced high-aluminum bauxite mainly consists of a mixture of two minerals: gibbsite (-Al2O3·H2O) and kaolinite.
Characteristics:
1. What is the fire resistance of high-aluminum refractory bricks? What are its characteristics?
The fire resistance of high-aluminum refractory bricks is higher than that of clay bricks and semi-silica bricks, reaching 1750~1790°C, belonging to advanced refractory materials.
2. What is the load-softening temperature of high-aluminum refractory bricks?
Due to the high Al2O3 content in high-aluminum products and fewer impurities, there is less formation of fusible glassy substances, so the load-softening temperature is higher than that of clay refractory bricks. However, because the mullite crystals have not formed a network structure, the load-softening temperature is still not as high as that of silica bricks. Regarding slag resistance, high-aluminum refractory bricks contain more Al2O3, making them closer to neutral refractory materials, capable of resisting both acidic and basic slags. However, since they also contain SiO2, their ability to resist basic slags is weaker than their ability to resist acidic slags.
Manufacturing Process:
The production process of high-aluminum refractory bricks is similar to that of multi-clinker clay refractory bricks, but the difference lies in the higher proportion of clinker in the formulation, which can reach up to 90~95%. Clinker needs to be carefully selected and graded before crushing, and iron is removed through screening. The firing temperature is relatively high, typically ranging from 1500~1600°C for first and second-class high-aluminum bricks when fired in tunnel kilns.
Refractory experts have proven through the production of high-aluminum refractory bricks that strictly selecting and grading high-aluminum clinker before crushing, and storing it by grade, as well as adopting a method of fine grinding with bauxite clinker and bonding clay, can improve product quality.
What are the uses of high-aluminum refractory bricks?
Uses: Primarily used for constructing blast furnaces, hot blast stoves, electric furnace roofs, cupola furnaces, reflection furnaces, and rotary kiln linings. Additionally, high-aluminum bricks are widely used as checker bricks in regenerative systems, nozzles, and water mouth bricks in casting systems. However, due to the higher cost of high-aluminum bricks compared to clay bricks, they are only used where clay refractory bricks cannot meet the requirements.
By: http://www.sdyaozhong.com/