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Introduction to High Alumina Bricks


1. Introduction

High alumina brick is a kind of refractory material, the main component of this refractory brick is AL2O3.

If Al2O3 content is higher than 90%, it is called corundum brick. Due to different resources, national standards are not completely consistent. For example, European countries set the lower limit of Al2O3 content for high-alumina refractories at 42%. In China, according to the content of Al2O3 in high alumina bricks, it is usually divided into three grades: Grade I──Al2O3 content>75%; Grade II──Al2O3 content is 60~75%; Grade III──Al2O3 content is 48-60%.

Aluminum silicate refractory products with aluminum oxide (Al2O3) content higher than 48%.

A neutral refractory with an alumina content of more than 48%. It is formed and calcined from bauxite or other raw materials with high alumina content. High thermal stability, refractoriness above 1770℃. It has good slag resistance and is used to build the lining of steel-making electric furnaces, glass melting furnaces, cement rotary furnaces, etc.

High-load, soft, low-creep high-alumina bricks are high-grade refractory materials made of special grade bauxite, fused corundum, and fused mullite as the main raw materials. This product has the advantages of small high-temperature creep, strong corrosion resistance, and good thermal shock stability. It is suitable for large and medium-sized hot blast stoves. It opens up the next step for the localization of high-quality and high-grade imported refractories required by my country's new hot blast stoves. The road to success has been included in the national "Spark Plan" project.

2. The production process The production process of high alumina brick and multi-clinker clay brick is similar. The difference is that the proportion of clinker in the ingredients is higher, which can be as high as 90~95%. The clinker needs to be sorted and sieved to remove iron before crushing. , The firing temperature is relatively high, such as high alumina bricks such as Ⅰ, Ⅱ, etc., when they are fired in a tunnel kiln, it is generally 1500~1600℃.

Production practice in China has proved that before crushing, high-aluminum clinker is strictly sorted and classified, and stored in tiers. The use of bauxite clinker and combined clay fine grinding method can improve product quality.

3. Raw materials According to different resource conditions and product requirements, the following types of raw materials can be used: high alumina bauxite mainly composed of hydrated bauxite minerals (monohydrate, gibbsite, etc.); sillimanite group minerals ( Including kyanite, andalusite, sillimanite, etc.); synthetic raw materials, such as industrial alumina, synthetic mullite, fused corundum, etc. China is rich in resources of high-alumina vanadium, with good quality, and its production areas are mainly distributed in Shanxi, Henan, Hebei, Guizhou, Shandong and other places. The high alumina bauxite produced is mainly a mixture of two minerals: monohydrate (α-Al2O3·H2O) and kaolinite.

Four, characteristics

a. The refractoriness of aluminum bricks with high refractoriness is higher than that of clay bricks and semi-silica bricks, reaching 1750~1790℃, which belongs to advanced refractory materials.

b. Load softening temperature Because high aluminum products have high Al2O3, less impurities, and less fusible glass, the load softening temperature is higher than that of clay bricks, but because mullite crystals do not form a network structure, the load softening temperature is still Not as high as silica bricks.

c. The slag resistance high alumina brick contains more Al2O3, which is close to neutral refractory materials, and can resist the erosion of acid slag and alkaline slag. Because it contains SiO2, the ability to resist alkaline slag is weaker than that of acid slag. some.

5. Uses Mainly used for lining of blast furnaces, hot blast furnaces, electric furnace tops, blast furnaces, reverberatory furnaces, and rotary kilns. In addition, high alumina bricks are also widely used as open hearth regenerative checker bricks, plugs for pouring systems, nozzle bricks, etc. However, the price of high alumina bricks is higher than that of clay bricks, so it is not necessary to use high alumina bricks where clay bricks can meet the requirements. Stack