The tuyere composite bricks generally use composite brown corundum bricks or corundum mullite bricks, and the composite brown corundum bricks and corundum mullite bricks have poor resistance to slag erosion and alkali erosion. Compared with bauxite, fused corundum has a dense structure, complete crystals, and is not easily corroded by alkali and slag.

It can be seen from the physical property test results of composite brown corundum brick and corundum mullite brick (tuyere combined brick) (Table 1) that the main disadvantage of these two kinds of bricks is poor alkali resistance and slag corrosion resistance. For blast furnace refractories, these two properties are particularly important. In addition, the air permeability of these two kinds of bricks is very high, up to 140mDa, with few micropores, the average pore size is as high as 13.00μm, and the pore volume rate of <1μm is only 14.66%. In particular, the volume expansion of corundum mullite bricks after alkali resistance is very large. For example, the volume expansion of corundum mullite bricks after alkali resistance reaches 12.44%.

Therefore, the composite brown corundum brick and corundum mullite brick are easily corroded by slag and alkali metal due to the base material, and the air permeability of the brick is very high, K, Na, Zn, deposited carbon, etc. Corroded brick body. In particular, due to the continuous invasion of alkali metals, volume expansion is constantly generated, which makes the tuyere upturn and affects the production of blast furnaces.

Microporous corundum bricks are used as ceramic cups in WISCO No. 6 blast furnace (3200m3) and 7 blast furnaces (3200m3), and the application effect is very good. For this reason, the No. 5 blast furnace (3200m3) of Wuhan Iron and Steel is overhauled and the new No. 8 blast furnace (3800m3) is combined with the tuyere bricks. Changed from corundum mullite brick to microporous corundum brick.

Microporous corundum brick has the advantages of excellent alkali resistance, excellent slag corrosion resistance and excellent thermal shock stability. It belongs to microporous brick and other properties, which is better than corundum mullite brick and is very suitable for blast furnace tuyere belt application, Wuhan Iron and Steel No. 5 The second generation of blast furnace has been used for more than 6 years, and the current use effect is very good, and there is no tuyere upturn.