How to improve the service life of electric arc furnace lining

Furnace lining life is an important economic and technical indicator of electric arc furnace steelmaking, which directly affects the operating rate, power consumption and consumption of resistant materials of the electric arc furnace. Therefore, increasing the life of the electric arc furnace lining is of great significance to increase the output and the steelmaking operation rate.

To improve the service life of electric arc furnace lining, please notice:

1 Strictly lining the working layer of the furnace lining and the furnace bottom furnace slope knotting

The working layer of the furnace wall is dry-layed with magnesia-carbon bricks, stacked in staggered fashion, and the brick gap should be less than 1mm. During the masonry, internal cracks should be prevented from impact, which will cause breakage and block loss during use, which will affect the service life. The furnace bottom and the furnace slope working layer are knotted with magnesia ramming material. The first layer of magnesia is properly spread (about 40% of the total thickness), and rammed from the furnace edge to the center with a pressure vibration hammer. The center is rammed radially to the edge, and each layer is rammed 3 times, so that the hammers and hammers interlock with each layer. The air-pressure vibrating fork used for ramming furnace slope fully discharges the air in the magnesia ramming material by vibration, so as to achieve smooth ramming, high density and strong integrity. The slope angle of furnace is controlled to be less than 45°, which is convenient for later maintenance. When a new furnace is opened with a qualified furnace lining, the furnace bottom is covered with a thin steel plate to prevent the impact of the charging on the furnace bottom from damage. At the same time, moisture-proof measures must be taken after the offline masonry is qualified.

2. Do the baking and sintering of the new furnace lining

A high-quality furnace lining must have sufficient strength after baking and sintering, and the entire furnace lining must be integrated. The smelting of the first three furnaces before opening a new furnace is mainly based on baking the furnace lining, and all-scrap smelting is implemented to prevent the impact damage of the molten iron to the furnace lining. In principle, the scrap steel is added in 2 to 3 batches. Shock. It adopts short arc and low power supply, the secondary voltage is controlled at 45~650V, and the secondary current is controlled at 40~45KA. The furnace wall cluster oxygen lance uses the burner mode to blow oxygen to boost the melting, and the oxygen flow of each lance is controlled below 750Nm³/hr to reduce the impact of the high-speed cluster oxygen flow on the furnace bottom. After each batch of materials is melted through the well to form a molten pool, the furnace must be powered off for 30 minutes, and the temperature of the molten steel is used to ensure the low-temperature sintering compactness of the furnace lining.

3. Optimize the operation process to reduce the erosion of the furnace lining due to improper operation

Reasonable loading and distributing, base with light and thin materials to prevent the impact of heavy materials on the furnace bottom and furnace slope from causing pits and accelerate the damage of refractory materials. After the basic molten pool is formed in the smelting and melting period, it is necessary to inject or add carbon powder into the molten pool through the furnace wall carbon powder spray gun or the fourth feeding hole in time, and the furnace wall cluster oxygen lance should be switched to the oxygen blowing mode, and in time according to the furnace conditions Adjust the oxygen flow ratio of the three furnace wall oxygen lances to promote the CO reaction to generate CO gas volume, increase the permanent foaming height of the molten pool slag, quickly realize the foam slag submerged arc operation, and reduce the arc arc and high temperature molten steel corrosion of the furnace lining . At the end of smelting, as the CO reaction weakens, the foamed slag gradually thins. After the furnace door automatically flows slag, it is necessary to add slag material and light burned dolomite in time to ensure that the slag alkalinity is always controlled at 2.0 ~ 2.5 and the original slag ( The content of MgO) is between 5% and 8%, which reduces the corrosion rate of the furnace lining. Promote the operation of retaining steel and slag to ensure that 15-20t of steel is retained in the furnace. After tapping, 500kg of lime is added to thicken the slag, which reduces the impact of charging on the furnace lining, and is also conducive to the early production of the next furnace. The slag with a certain alkalinity reduces the free state of SiO₂, P₂O5, Fe₂O₃ and other oxides in the slag to react with the MgO in the refractory material, which reduces the surface melting point of the refractory lining and aggravates the damage of the lining.

4. Strengthen the maintenance of the later furnace lining

The maintenance of the main parts of the furnace lining in the later period plays an important role in prolonging the service life. The lower area of the oxygen lance on the furnace wall and the electrode “hot spot” area should be strengthened with gunning measures, and the timing of tapping and the temperature in the furnace should be used for high temperature quick repair. , Thin patch, the gunning thickness is controlled at 10-20mm, in order to improve the adhesion rate of the gunning material and the effect of rapid high temperature sintering. In the later period of use, pay attention to observe the erosion status of the furnace slope, and timely use the ramming material to pad the furnace slope to ensure that the angle of the furnace slope is always maintained at about 45° to prevent serious deformation of the furnace slope. At the same time, it is necessary to prevent the furnace slope from rising due to improper shimming, reduce the volume of the molten pool, increase the steel surface, and affect the stable and smooth operation of the operation.

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