01 furnace body and middle part
The working environment temperature of the furnace body and middle part is low, and there is no danger of slag formation and slag corrosion. However, it must withstand abrasion from solid materials, erosion by high-temperature airflow and certain chemical erosion. Therefore, the furnace body and middle lining are mostly made of high-quality clay bricks and high-alumina bricks with low porosity, or even phosphate-bonded clay bricks or sillimanite refractory bricks with good spalling resistance and wear resistance.
02Lower part of furnace body
There have always been two opinions on the selection of refractory materials for the lower part of the blast furnace body. The refractory school believes that the damage to the refractory material in the lower part of the furnace body is mainly caused by high-temperature wear and chemical erosion, so it is recommended to use high-quality aluminum silicate and silicon carbide products with low conductivity, high strength and strong corrosion resistance, such as corundum, Sialon Combined with SiC bricks etc. The thermodynamics school believes that temperature fluctuations are the main factor causing damage to the blast furnace lining, and recommends configuring an efficient cooling system and selecting high thermal conductivity materials such as carbon and graphite as lining materials to reduce the hot surface temperature of the furnace lining and resist high temperatures. Strong thermal shock; at the same time, it promotes the formation of a protective layer of slag skin to extend the service life of the lining refractory material.
03 furnace belly, furnace waist
The furnace belly, furnace waist and lower part of the furnace body are the key areas where materials in the blast furnace react with each other. They are also subject to material wear, erosion by hot air flow, erosion by harmful elements, and erosion by molten materials. Therefore, the refractory materials used in this part must have good corrosion resistance, oxidation resistance, alkali resistance, high thermal conductivity, thermal shock resistance and wear resistance.
04 Hearth and furnace bottom
In addition to being affected by high temperatures, the refractory materials of the furnace bottom and hearth are also subject to chemical erosion by slag iron and erosion by molten iron. At the same time, the erosion by alkali and zinc is also very serious. Therefore, the furnace bottom and hearth refractory materials need to have good corrosion resistance, permeability, alkali resistance, etc. At present, blast furnace bottoms and hearths at home and abroad mainly use two structures: full carbon and carbon materials-ceramics.
The all-carbon material structure believes that by using semi-graphite carbon blocks with high thermal conductivity, heat can be quickly transferred to the cooling system to achieve thermal balance. At the same time, this is also conducive to reducing the temperature of the working surface, promoting the formation of slag-like attachments, and pushing the 800°C isotherm beyond the carbon bricks to achieve the safety and longevity of the hearth system.
Carbon material-ceramic material composite structure design While agreeing with the all-carbon material structure design, it is believed that adding a ceramic cup made of ceramic materials with good corrosion resistance, erosion resistance and thermal shock resistance will combine the carbon material in the furnace with the molten iron and The separation of other mixtures can prevent the erosion of the carbonaceous material furnace by molten iron within a period of time, thereby achieving the safety, efficiency and longevity of the furnace system. For example, Baosteel’s No. 2 blast furnace has a carbon material-ceramic material composite furnace bottom and hearth structure.