How to choose refractory bricks for each part of the blast furnace?

blast furnace is a large-scale pyrometallurgical furnace that uses coke to reduce iron ore to smelt molten iron. The temperature, pressure, physical and chemical properties and harsh working conditions of the lining at different heights of the blast furnace are different. Therefore, the mechanism and conditions of lining failure are also different, and the choice of refractory materials is naturally different.

① Furnace Throat

blast furnace throat is the throat of the blast furnace, which is easily damaged by impact and friction during the blanking process. Masonry is generally built with high-hardness, high-density high-aluminum bricks, and protected by wear-resistant cast steel guards.

②Stove body

The furnace body is the part from the furnace throat to the middle of the furnace waist, which is divided into three areas: upper, middle and lower. The middle and upper lining of the furnace lining is mainly worn and corroded by the falling material and the rising dust-containing air flow, and the damage is relatively light. Under normal circumstances, special clay bricks, dense clay bricks, and high alumina bricks with low free Fe2O3 content can also use clay amorphous refractories. The lower part of the furnace body has a high temperature and a large amount of slag is formed. The slag is in direct contact with the surface of the furnace lining, and the furnace lining is damaged rapidly. Masonry generally chooses high-quality compact clay bricks or high alumina bricks with good fire resistance, slag resistance, high temperature structural strength and wear resistance. The lower part of the large blast furnace shaft mainly uses high alumina bricks, corundum bricks, carbon bricks or silicon carbide bricks.

③Furnace waist

The waist is the widest part of the blast furnace. The chemical erosion of slag, alkali metal vapor, and the friction and wear of blanking and high-temperature coke on the surface of the furnace lining are very serious, making it one of the most vulnerable parts of the blast furnace. Medium and small blast furnaces can use high-quality dense clay bricks, high alumina bricks, and corundum bricks; large modern blast furnaces generally use high alumina bricks, corundum bricks or silicon carbide bricks, and carbon bricks can also be used for masonry.

④Stove belly

The belly of the furnace is located below the waist of the furnace and has an inverted cone shape. Generally speaking, the blast furnace is almost completely damaged shortly after it is opened. Therefore, high-alumina bricks (Al2O3<70%) and corundum bricks are used in the hearth. Carbon brick, graphite petroleum coke, graphite anthracite and other semi-graphite bricks are widely used in modern large blast furnaces.

⑤ Hearth

The hearth is mainly affected by the chemical erosion, erosion and alkali erosion of molten slag and molten iron. At the bottom of the furnace, molten iron seeps into the cracks of the bricks, causing the refractory to float and damage. The masonry generally uses carbon bricks with high fire resistance, high high temperature strength, good slag resistance, strong thermal conductivity, high bulk density and good volume stability.