Blast furnace refractory bricks
The blast furnace is a large high-temperature metallurgical furnace that uses coke to reduce iron ore to smelt molten iron. The temperature, pressure, nature of physical and chemical changes, and harshness of working conditions experienced by the lining at different heights in the blast furnace are different. Therefore, the mechanism and condition of lining damage are also different, and the selection of refractory materials is naturally different.
01 Throat
The throat is the throat of the blast furnace, which is easily damaged by the impact and friction of the descending solid charge. It is generally built with high-aluminum bricks with high hardness and density, and protected by wear-resistant cast steel guard plates.
02 Furnace body
The furnace body is the part between the furnace throat and the furnace waist, which is divided into three zones: upper, middle and lower. The upper and middle linings are mainly subject to wear and erosion by the descending charge and the ascending dust-laden airflow, and the degree of damage is relatively light. Generally, special clay bricks containing low free Fe2O3, or dense clay bricks, or high-alumina bricks are used for blast furnaces. It can also be made of clay amorphous refractory materials. The temperature of the lower part of the furnace body is higher, 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 quickly. Generally, high-quality dense clay bricks or high-alumina bricks with good refractory performance, strong slag resistance, high-temperature structural strength and good wear resistance are selected for masonry. The lower part of the large blast furnace body is mainly built with high-alumina bricks, corundum bricks, carbon bricks or silicon carbide bricks.
03 Furnace waist
The furnace waist is the widest part of the blast furnace. The chemical erosion of slag, the erosion of alkali metal vapor, and the friction and scouring of the furnace lining surface by descending furnace charge and high-temperature coke are very serious, making it one of the most vulnerable parts of the blast furnace. Small and medium-sized blast furnaces can use high-quality dense clay bricks or high-alumina bricks, corundum bricks; large modern blast furnaces generally use high-alumina bricks, corundum bricks or silicon carbide bricks, and some are built with carbon bricks.
04 Furnace belly
The furnace belly is located below the furnace waist and is an inverted cone. Generally, the blast furnace is almost completely destroyed soon after the furnace is opened. Therefore, high-alumina bricks (Al2O3>70%) and corundum bricks are used for the furnace belly. Modern large blast furnaces generally use carbon bricks and semi-graphite bricks such as graphite-petroleum coke and graphite-anthracite.
05 Furnace hearth
The furnace hearth is mainly subject to chemical erosion, scouring and alkali erosion by slag and molten iron. The furnace bottom is mainly damaged by molten iron penetrating into the brick joints, causing the refractory materials to float. Generally, carbon bricks with high refractoriness, high high temperature strength, good slag resistance, strong thermal conductivity, high bulk density and volume stability are used for masonry.
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