Reasons and measures of cracks in high alumina bricks due to raw materials

January 07, 2019

Cracks in high aluminum bricks are common causes of waste products in the production of high alumina bricks. The main raw material for producing high alumina bricks is high alumina bauxite clinker, in which the impurities and the degree of sintering cause cracks on the surface of the product.

Poorly sintered clinker continues to shrink and become uneven during the firing of the product, causing cracking of the products. At the same time, in the process of firing of the products, the secondary mullite of the poorly sintered clinker itself is still going on. The secondary mullite petrochemical mainly refers to SiO2 of the clay and Al2O3 of high alumina clinker in the production of high-aluminum bricks to form mullite, accompanied volume expansion, resulting in inconsistent shrinkage of products, an increase in the number of surface cracks and the degree of cracking is increased.

cracks in high alumina bricks

Improvement measures:

The main mineral compositions of high alumina bricks are mullite, corundum and glass phase. As the increase of Al2O3 content in the products, the amount of mullite and corundum phase also increases, the glass phase decreases correspondingly, and the refractoriness and high temperature performance of the product increase. In the actual production of high alumina bricks, it is necessary to control the impurity content of the used high-alumina bauxite clinker, and the raw materials with low impurity content and good sintering degree should be used as far as possible.

Generally, the sintering degree of the clinker can be judged by detecting the water absorption rate of the clinker. In the production process, clinker with low water absorption rate can be used to produce high alumina bricks, which can effectively reduce cracks on the surface of the products. Practice has shown that in order to avoid and reduce the network cracks on the surface of high alumina bricks, the water absorption rate of high alumina bauxite clinker is controlled below 2.5%~5.0%.

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