During blast furnace smelting, the working environment of refractory bricks in various parts is very harsh, but there are some subtle differences. The following is a detailed explanation based on the environment of each part of the blast furnace.
1. Blast furnace refractory of furnace throat:
It mainly protects the furnace lining. When the furnace throat is working normally, the temperature is 400~500℃, and it is more intensely affected by the impact and friction of the furnace material, and it is very easy to wear. Therefore, the furnace throat is generally built with high-alumina refractory bricks, and the furnace throat steel bricks are generally made of steel parts. Even so, the corrosion of the furnace throat is still inevitable, especially the lower edge of the furnace throat steel brick is more prominently affected by the impact of materials. .
2. Blast furnace refractory of furnace body:
It is an important part of the blast furnace body, which plays the role of heating, reducing and slagging of the charge. The refractory brick lining bears the erosion of the gas flow and the impact of the material from beginning to end. However, the upper and middle parts of the furnace have lower temperatures (400~800℃), and there is no slag formation and slag corrosion hazards. This part of the refractory brick is mainly subjected to the impact of the charge, the abrasion or thermal shock of the rising of the furnace dust (up to 50℃/min), or is damaged by the intrusion of alkali, zinc, etc., and the deposition of carbon.
In other words, the life span of the blast furnace has a lot to do with the life span of the furnace body. Therefore, this part (especially the lower part of the furnace body) requires the selection of high-quality clay bricks, high-alumina refractory bricks and corundum bricks with good slag resistance, alkali resistance, high temperature strength and wear resistance.
3. Blast furnace refractory of furnace waist:
it acts as a buffer for the rising gas flow. The charge has been partially reduced to slag here, the air permeability is poor, and the slag corrodes the refractory brick seriously. In addition, the temperature of the furnace waist is 1400~1600℃, high-temperature radiation erosion is serious; alkali corrosion of refractory bricks is also serious; the dusty hot furnace gas rises, which has a strong scouring effect on the furnace lining; coke and other materials produce friction ; When hot air passes through, it causes a sharp change in temperature. Therefore, the furnace waist is also an extremely vulnerable area, which directly affects the life of the blast furnace.
4. Blast furnace refractory of hearth:
The hearth is connected to the hearth and the hearth. Generally, the design of the upper part and the lower part is also suitable for the increase of the gas volume and the reduction of the volume after the charge becomes slag iron. The temperature in this area is higher. The lower charge temperature is about 1600~1650°C, the airflow temperature is also high, and a large amount of intermediate slag (referring to the slag whose composition and temperature are constantly changing during the dripping process, called belly slag abroad) began to drip. Therefore, the heat radiation and molten slag on this part are very serious for the corrosion of refractory bricks. In addition, the intrusion of alkali metals, the chemical action caused by carbon deposition, the scouring action of the melt from the top down and the hot air flow from the bottom up are also intensified. Therefore, the refractory bricks in this part have always been the vulnerable area of the blast furnace.
5. Blast furnace refractory of hearth and bottom:
The hearth mainly plays the role of burning coke and storing slag and iron. The hot air blown by the tuyere first burns with coke to produce coal gas (that is, the initial distribution of coal gas) for blast furnace smelting and reduction. The tuyere area is the area with the highest temperature in the blast furnace, generally above 1700~2000℃. Slag iron, the final product of ironmaking production, also accumulates in the hearth and is periodically discharged from the slag hole and the iron hole. Refractory bricks (especially carbon bricks) lining the hearth are mainly eroded and corroded by molten iron slag. The bottom of the furnace is mainly to protect the hearth and avoid the leakage of slag and iron. However, the brick lining of the furnace bottom is mainly eroded by molten iron, and even damaged. The intrusion of molten iron can cause the refractory bricks to float up, and chemical attack can cause the expansion of the embrittlement layer of the refractory bricks; thereby causing serious damage to the refractories at the bottom of the blast furnace. Since the refractory brick lining of the hearth and furnace bottom is not easy to repair after being corroded, the degree of damage often determines the life of a blast furnace. This part requires the refractory to be resistant to corrosion and penetration of molten iron, alkali resistance and thermal conductivity.
6. Blast furnace refractory of taphole:
As the blast furnace becomes larger and larger, the number of tapping times per day increases, and the working conditions of the taphole are quite harsh. The tap hole is not only subject to the erosion and friction of molten iron circulation, slag, and alkali, but also to the thermal shock caused by the temperature change from tapping to the end of tapping. At the same time, it is also subject to the machinery when the tap hole is opened or blocked. Vibration damage.
7. Blast furnace refractory of taphole:
The blast furnace taphole is a channel through which high-temperature molten iron or molten slag flows. Its lining is mainly eroded and infiltrated by molten iron, molten slag and trace elements. This requires that the refractory material used in the iron trough not only has strong resistance to slag molten iron erosion, but also has good high temperature resistance. At the same time, flue gas, dust, powder particles, etc. have a certain pollution effect on the surroundings, so the environment of the iron casting plant is relatively harsh. Many countries pay great attention to environmental protection work. On the basis of the longevity of the tap channel lining, a lining cover and a dust suction device are installed, which greatly improves the working environment in front of the blast furnace.
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