Blast furnace is a large metallurgical equipment, usually made of steel structure and a variety of refractory materials, which is mainly used as a high temperature reaction furnace for converting iron ore into molten iron.
Blast furnaces are an important part of steel production, and their linings need to withstand high temperatures, high pressures, and the erosion of molten metal. The choice of refractory for the lining is based on the environment in which it is required.
The blast furnace can be divided into five parts, namely, furnace throat, furnace body, furnace waist, furnace belly and furnace cylinder. The temperature and environment of each part of the blast furnace are different, and the selection of refractory materials for lining is also different. Refractories for lining each part of the blast furnace should be reasonably selected according to the specific working temperature and working environment, so as to ensure the stability of the furnace body.
Blast furnace lining with refractory materials surrounded by the blast furnace type, blast furnace internal circular workspace, the size of the blast furnace to the effective volume of the number of cubic meters. In the blast furnace lining in the use of harsh conditions of the location of the cooling device protection, so that a generation of working furnace age can be up to 15 years or more.
The furnace throat is at the top of the blast furnace, the temperature is low, bear the blast furnace gas scouring and the impact of the charge. Therefore, the furnace throat plays the role of protecting the upper furnace lining, reasonably distributing the charge and limiting the gas to take away a large amount of ash. Usually in the selection of refractory materials are high aluminum bricks and cast steel plate protection.
Blast furnace body is long, the lower part of the higher temperature, mainly plays the role of preheating, heating, reducing and slagging. In order to make the charge go down smoothly and preheat, usually the furnace body has a certain inclination. The middle part of the furnace body usually adopts clay or clay indefinite refractory material for masonry, and the lower part of the furnace body has higher temperature and higher degree of damage, so it usually chooses high-quality Fireclay bricks or high alumina bricks with good slag resistance, or corundum bricks with higher slag resistance and thermal conductivity.
The temperature of furnace waist is 1400~1600℃, which is high. The charge has been partially reduced to slag in the furnace waist, with poor permeability and serious slag erosion. At the same time the lower part of the rising airflow scouring serious, coke friction is serious, so the part of the furnace lining damage is serious. So in the selection of often to Fireclay bricks, high alumina refractory bricks, corundum refractory bricks, carbon bricks.
The furnace belly is connected to the furnace waist and the furnace cylinder, in order to adapt to the expansion of the high temperature furnace gas and the contraction of the molten material, it is usually designed as the shape of the upper large and lower small. At the same time, this part is close to the air outlet, which is also affected by the scouring of high temperature gas flow, slag-iron separation and erosion in the process of slag-iron drop, so this area is the most vulnerable area in the operation of the blast furnace. The furnace belly is usually made of high alumina brick or corundum brick.
Furnace cylinder and furnace bottom mainly play the role of burning coke and storing iron. The hot air coming in from the air outlet reacts with the coke to produce gas at a temperature of more than 2,000°C. Therefore, the refractory materials in the air outlet area are used at a temperature of more than 1,700°C. The refractory materials used in the furnace bottom area are mainly high alumina bricks or corundum bricks.
The molten steel in the furnace tank is discharged from the outlet regularly, and the high-speed hot air also blows the molten iron in the furnace tank, causing the molten iron to form a whirlpool in the furnace tank, so the refractory material of the furnace tank is subjected to the scouring and erosion of the high-temperature molten iron, and so the carbon bricks are generally used as the refractory material.
The dead iron layer of iron contained in the bottom of the furnace will penetrate into the refractory material, and the carbon in the iron will also cause the embrittlement of the refractory material, so the bottom of the furnace is easy to cause elephant foot erosion, the bottom of the furnace is generally used for high-quality clay bricks or high alumina bricks as masonry materials.
There are many factors affecting the life of a blast furnace, and the degree of deterioration of the lining is a fundamental factor. Practice has shown that furnace lining life varies with smelting conditions.
The furnace belly, furnace waist and lower part of the furnace body are the most serious parts of the blast furnace lining erosion, especially the waist and lower part of the furnace body, which are difficult to form a protective layer, and have become the weakest links of the blast furnace lining at present. The throat is mainly affected by the friction of solid charge and the scouring effect of the blast furnace gas flow with furnace dust, as well as the influence of the rapid change of temperature when the charge is loaded.
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