Blast furnaces are divided into two types: open and closed. The highest operating temperature of the furnace melting zone is generally 1350℃. The upper lining of the furnace body is mainly subject to mechanical wear of the charge. The refractory material is generally built with clay bricks, and the service life is about 3 years; the lining of the tuyere area and the inclined furnace wall above it is directly built with bricks, which are mainly subject to high temperature, air flow scouring and chemical erosion, and are more easily damaged.
Refractory materials for blast furnaces must cope with the challenges of high temperature, mechanical stress and chemical erosion to ensure their structural integrity and operating efficiency. Which types of refractory bricks are suitable for blast furnace refractory materials?
1: Carbon bricks
Carbon bricks are widely used in the bottom and hearth of blast furnaces due to their high temperature stability and excellent electrical conductivity. Carbon bricks can maintain structural stability at high temperatures above 1700°C, and have good electrical conductivity, which can effectively guide the current in the furnace and reduce resistance loss. This makes carbon bricks particularly suitable for areas that come into contact with high-temperature molten iron and slag, such as the furnace bottom and furnace hearth, providing excellent wear resistance and erosion resistance, significantly improving the service life of the furnace bottom.
2: High alumina bricks
High alumina bricks contain a higher proportion of alumina (Al2O3) and have a refractoriness of up to 1750°C or more, making them ideal for the furnace belly and furnace body in blast furnaces. High-alumina bricks have good wear resistance and thermal shock resistance, and can withstand the erosion of charge and rapid temperature changes. Its high refractoriness makes it perform well in supporting and protecting the furnace wall from the wear of charge and airflow, and is particularly suitable for use in the medium and high temperature zones of blast furnaces, such as the furnace belly and furnace body, providing excellent thermal stability and structural protection.
3: Magnesia chrome bricks
Magnesia chrome refractory bricks are mainly made of magnesia sand and chrome ore, and have ideal high-temperature performance and resistance to alkaline slag erosion. In blast furnaces, magnesia chrome bricks are often used in the furnace hearth and throat areas, and can resist the erosion of high-temperature slag and alkaline substances. Its high temperature strength and chemical corrosion resistance make it an ideal material for handling molten iron and slag. This brick maintains structural stability in high temperature areas while providing good wear resistance and erosion resistance, making it an important material for high temperature parts of blast furnaces.
4: FireClay bricks
Clay bricks are usually used in the outer layer and low temperature area of blast furnaces due to their good heat resistance and cost-effectiveness. Clay bricks can provide effective thermal insulation at lower temperatures while having certain erosion resistance. They are often used in the low temperature areas of the furnace body and throat to provide basic thermal protection and structural support. Although not as high-alumina bricks or magnesia-chrome bricks in terms of high temperature resistance and wear resistance, clay bricks are still refractory materials in blast furnaces due to their economy and easy processing.
The vaporization cooling water jacket is used and lined with clay bricks to enhance heat conduction and form a protective layer on the working surface slag skin, thereby increasing its service life; the main furnace bed carries and stores copper liquid, the non-working layer is built with clay bricks, and the working layer is built with refractory materials such as magnesia refractory bricks, magnesia-chrome bricks or chrome bricks, and the service life is generally about 2 years. The front bed is a rectangular trough. The bottom of the trough is built with clay insulation bricks and clay bricks, and then the leveling layer is rammed with magnesia refractory ramming material. Then, the entire trough working layer is built with magnesia chrome bricks or chrome bricks. The lining of the bed has a long service life, and the lining of the slag line of the trough wall is more easily damaged, and its life is also more than half a year.
Refractory materials need to be used in combination to fully meet the requirements of different parts of the blast furnace, ensure its long-term stable operation, and extend the service life of the equipment.
