Blast furnace belly is a cylindrical transition section located between the bosh and the shaft. It is one of the weak points of the blast furnace and can directly influence the service life of blast furnace. 

Blast furnace belly has the largest diameter. It plays a buffer role in the rise of the gas. Here the furnace charge has been partially reduced into slags. Air breathability is poor here. Increasing the diameter of the belly can improve the air breathability of the slag layer, but if the diameter is too large, the airflow in the edge will be difficult to control. 

 

Blast furnace belly should not be too high. Generally the large-size blast furnace is 2.0-3.0m, the middle-size is 1.0-1.8m and the small-size less than 1.0m. 

 

The temperature in the belly is high, generally 1400-1600℃, so the high temperature radiation erosion is serious here. A lot of slags are formed here and the primary slag has a high content of FeO, so the slag erosion is more prominent here. The gas flow and the primary slag contain alkali substances, so the alkali corrosion is severe too. The rising high temperature gas flow produces a strong scouring action on the belly. And since the belly has break angle, the scouring action here is stronger than that of other parts. When hot air passes through the belly, there will be dramatic changes in temperature here. Therefore, refractories with good resistance to slags, erosion, high temperature, wear and thermal shock are used here. 

 

Refractories used in the belly include high alumina brick, corundum brick, alumina carbon brick, SiC brick, Si3N4 bonded SiC brick, Sialon bonded SiS brick, hot-pressed graphite carbon brick, semi-graphite carbon-SiC brick and Sialon bonded corundum brick. However, so far, there is still no refractory that can fully meet the requirements of the belly. Currently the continuous work of this part mainly relies on controlling the edge air flow and enhancing cooling. 

 

Alumina carbon brick, SiC brick, Si3N4 bonded SiC brick, Sialon bonded SiS brick and Sialon bonded corundum brick have relatively better performance. If a sufficiently strong cooling system configuration is available, graphite brick is also the trend.