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Coping method for AOD refractories erosion problem

[06/11/2021]



(1)For the problem of early silica neutralization, after lime is added, the top gun is used to quickly heat up, and the oxygen from the top gun is used to blow down from above. Melting (dissolving) lime to form a slag steel gas emulsion, which is beneficial to the rapid neutralization and decarburization of silica.

(2)The double slag method is used in the smelting process. After the smelting is started, the silicon is burned to increase the temperature, the lime is melted (dissolved), and then high-carbon ferrochromium is added. After the high chromium is added, the temperature is increased to 1550°C and the temperature is melted. The silicon in the pool is basically oxidized. Pull the slag once to remove part of the silicon dioxide and take away part of the excess heat. After pulling the slag, add lime again to make slag to continue smelting.

(3)During the smelting process, the alkalinity of the slag is controlled at about 3.0. During the smelting, the slag becomes a paste, which is conducive to the adhesion of part of the slag to the furnace lining, which can effectively reduce the mechanical erosion of the slag, molten steel and furnace gas. Slow down the corrosion effect of FeO on the furnace lining. At the same time, it can also prevent parts from breaking and falling off. During the smelting cycle, the temperature is controlled to fluctuate between 1400°C and 1700°C, and the cold material is added in small amounts multiple times to reduce the range of temperature fluctuations and effectively reduce the thermal expansion and contraction fracture of the furnace lining.

(4)Bricks of different compositions are used in different parts of the furnace lining, 75% MgO and 15%-20% CaO are used for masonry above the slag line, and 85% MgO and 100%-15% CaO are used for the part below the slag line. The masonry of high-purity magnesia-calcium fire bricks. MgO has good resistance to silica chemical attack, but poor slag resistance. The content of calcium oxide is increased above the slag line, and the slag resistance is better, but the resistance to silica corrosion is poor, and it is improved at the part below the slag line. The content of magnesium oxide, and the part above the slag line increases the content of calcium oxide.

(5) Strictly control the end temperature of decarburization, prevent the temperature from exceeding 1750, and slow down the corrosion of carbon reduction to the furnace lining. Lengthen the length of the air muzzle and the refractory material on the side of the air gun to make it have a longer service life.
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