Refractory materials for the lining of various parts of the blast furnace

A blast furnace is an iron-making facility. Iron ore and coke are mixed into the blast furnace from the top of the furnace in proportion. At the lower air outlet, high temperature blast air (1000~1200℃) enters the blast furnace, and the redox reaction takes place inside the blast furnace to produce iron slag. The iron containing slag flows out from the lower iron opening of the blast furnace, separating iron and slag. Slag into the slag ditch, flushing water slag into the dry slag pit. The iron is either used to continue steel making or sent to the iron casting machine. Finally, the blast furnace gas is discharged through the de-dusting equipment. This is the whole process of blast furnace iron making.

With the development and progress of the steel industry in various countries, blast furnaces are gradually becoming larger, more efficient and longer-lived. For the refractory materials used in blast furnace lining also put forward higher requirements. For example, good refractoriness, high temperature stability, density, thermal conductivity, wear resistance and slag resistance, etc.

At present, there are many varieties of refractory materials used in blast furnaces, and the refractory materials used in each part are not the same due to the influence of furnace conditions.

Furnace throat part: Refractory material is used as protective lining for reasonable fabric. The temperature is 400~500℃. Subject to the direct impact and friction effect of the furnace charge, the airflow scouring effect is slightly lighter. Therefore, dense clay bricks, high alumina bricks, clay castables or spray coatings can be used for masonry.

The furnace body part is the more important part of the blast furnace, used for the heating and reduction of the charge. This part of the furnace is seriously affected by the scouring of the material and the high temperature airflow. The temperature in the middle of the furnace body is 400~800℃. Without the influence of slag erosion, it is mainly affected by the scouring of rising dust gas, thermal shock, alkali zinc and the destruction of carbon deposits. Therefore, the middle and upper part of this part is built with dense clay bricks, high alumina bricks, anti-peeling wear-resistant phosphate clay bricks, high alumina bricks and silica bricks. The lower part is masoned with dense wear-resistant clay bricks, high alumina bricks, corundum bricks, and silicon carbide bricks.

The furnace belly acts as a buffer for the updraft. Part of the charge is reduced to slag here. Therefore, the furnace lining is seriously eroded by the slag. The temperature here is as high as 1400~1600℃ at the top and 1600~1650℃ at the bottom. Subject to high temperature radiation, alkali erosion, hot dusty rising furnace gas and other comprehensive impact, the refractory lining here is seriously damaged, should be used to resist slag erosion strong, resistant to scouring and abrasion of refractory materials. The furnace abdomen can use low porosity clay bricks, high alumina bricks, graphite bricks, silicon carbide bricks, corundum bricks, etc. for masonry.

The furnace pot is the bearing part of the molten iron and slag, the highest temperature in the wind mouth area in 1700 ~ 2000 ℃, the furnace bottom temperature in 1450 ~ 1500 ℃. In addition to the influence of high temperature, the furnace cylinder lining is also subjected to the erosion of slag and iron scouring. The furnace cylinder wind mouth part can use corundum mullite brick, brown corundum brick, silica line brick for masonry. Slag iron contact hot surface use corundum mullite brick, brown corundum brick; cold surface use dense carbon brick, graphite semi-graphite carbon brick, microporous carbon brick, molded carbon brick. Brown corundum low cement precast blocks are used for the side walls. The bottom of the furnace uses graphite semi-graphite carbon bricks and microporous carbon bricks for masonry.

In addition, fie clay bricks, silicon carbide bricks, graphite bricks, electrofused corundum castables, silicon carbide castables, and hot spray repair materials for iron ditch can be used in the blast furnace discharge ditch area. Low-cement and high-alumina castables are used for the ditch cover. Low-cement corundum castables are used for the skimmer area. The refractory material for the swing nozzle is similar to that of the iron ditch. Slag outlet trench can use slightly lower material.