Blast furnace shaft is an important part of the blast furnace, heating the charge materials, reducing and forming slags. It is subjected to the erosion of coal gas and the impact of materials. 

In the upper and middle shaft, the temperature is low (400-800℃) and there is no slag formed and, so, no slag erosion. This part is mainly subjected to the impact of the charge materials, wear by the rising dust, thermal shock, invasion by alkali and zinc and carbon deposition. So this part is mainly built with low porosity fire clay brick and high alumina brick. With the increase of the variety and improvement of the quality of refractories, the service life of blast furnaces has been greatly expanded. 

 

However, with the increasingly demanding condition in large and medium blast furnaces and the need for longer service life, high quality refractories with better creep resistance and wear resistance are required in this part. Thus, phosphate bond fire clay brick is used in the upper shaft. Sillimanite brick and high alumina brick with excellent creep resistance are used in the upper and middle shaft. 

 

The lower shaft is the weakest point of the blast furnace shaft. The temperature is high. Frequent heat exchanges occur and many low-melt substances are formed in this part. It is subjected to the friction action of the dropping charge materials, wear of the dust and erosion of alkali vapor. Therefore, it is vulnerable to erosion. In serious situations, the cooler can be eroded completely and the furnace relies on the steel shell to maintain. Therefore, high quality fire clay brick, high alumina brick, corundum brick, alumina carbon brick and silicon carbide brick with good resistance to slags, alkali, high temperature and wear are used here. The liner with cooling plate structure also uses graphite bricks.

 

Since silicon carbide brick does not react with the molten slags, there is no nodulation. The silicon carbide brick liner can prolong the service life and improve thermal efficiency. Therefore. It is an ideal promising refractory for the blast furnace.