Application and damage of high alumina bricks in cement kiln

November 26, 2018

Application and damage of high alumina bricks in cement kiln

High alumina brick is a kind of neutral refractory material with alumina content [w(Al2O3)] above 48%. It is formed and calcined from bauxite or other raw materials with high alumina content. The mineral composition is corundum, mullite and glass phase, the content of which depends on the ratio of w(Al2O3)/w(SiO2) and the type and amount of impurities. According to the content of Al2O3, high alumina bricks in China are divided into three grades. The higher the Al2O3 content, the higher the refractoriness.

High alumina bricks are advanced refractory materials with high thermal shock resistance and good slag resistance. The content of Al2O3 in high alumina bricks is relatively close to neutral refractory material, which can resist the erosion by acidic slag and alkaline slag. Because it contains SiO2, the ability to resist alkaline slag is weaker than that of acid slag. High alumina bricks are mainly used for masonry blast furnaces, hot blast stoves, electric furnace roofs and reverberatory furnaces. They can also be used for open-hearth regenerative lattice bricks, plugs for gating systems and nozzle bricks. In the field of cement production, it is mainly used for the lining of rotary kiln.

The performance of high alumina brick can be improved by adding different raw materials into the matrix of high alumina brick to strengthen the matrix. The research shows that the composite high-alumina brick made of kyanite has the advantages of high load softening temperature, high strength and good thermal shock stability. High-aluminum brick made of zircon has high strength, good thermal shock stability, excellent resistance to alkali residue. The above two kinds of high alumina bricks have been used in place of ordinary high alumina bricks and phosphate combined with high alumina bricks in the corresponding parts of the cement kiln, and have achieved good results and improved the service life of the lining.

For high alumina refractories, when w(Al2O3) is less than 25%, it has good alkali corrosion resistance, but its refractoriness is low. The refractory material with higher alumina content has higher refractoriness, but the alkali corrosion resistance is poor. The material reacts with alkali to form KAS6, KAS2, K, Na, Al2O3, SiO2 alkali-aluminum-silicon minerals, which will expand in volume, damage and peel of materials, affect the service life.

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