Molten iron desulfurizing method

Abstract

The improved molten iron desulfurizing process outside blast furnace includes spraying deactivated magnesia grains as desulfurizing agent via high-precision automatically regulating material feeding mode; desulfurizing in the molten iron ladle with water cooling hood to prevent adhesion of desulfurizing dross and molten iron; slag-iron separation in the same separator and feeding pure molten ironinto pig iron mixer or molten iron ladle. The said process has the features of less investment, simple process, low production cost and easy maintenance.

Description

technical field [0001] The invention relates to an out-of-furnace desulfurization method of molten iron by spraying passivated magnesium particles into molten iron with inert gas, is an improved method of the desulfurization process, and belongs to the technical field of out-of-furnace pretreatment of molten iron in the metallurgical industry. Background technique [0002] The existing powder spraying desulfurization process flow outside the blast furnace molten iron furnace is as follows: before desulfurization of the blast furnace molten iron, use a slag scraper to remove the scum out of the molten iron ladle for the first time, and directly desulfurize it in the molten iron tank after the slag removal. Spray CaO-Mg powder or passivated magnesium particles in the molten iron tank to make the sulfur in the molten iron generate CaS and MgS and float to the surface of the molten iron, then use the slag scraper to remove the desulfurization scum on the surface of the molten iro...

AI Technical Summary

Problems solved by technology

The disadvantages of the above process are firstly to carry out one or two slag removal, the process is complicated, the process takes up to 8-10 minutes, the temperature drop of molten iron is large, and the iron loss increases. Second, the slag and iron cannot be completely separated after desulfurization, and there is iron in the slag , there is slag in the iron, which affects the quality of molten iron, because the desulfurization slag and molten iron enter the steelmaking furnace together. There are many difficulties in smelting; the third is that the slag removal machinery used is complicated and heavy, which not only increases the cost of slag removal, but also increases the production cost

[0003] In the desulfurization process of molten iron, the commonly used desulfurizing agent spraying powder feeding system is a mixed spraying method, the equipment is huge, complex, occupies a large area, the cost of desulfurization is high, and the temperature drop of molten iron is large

There is another way, such as the pure spray passivation magnesium feeding system of the Ukrainian Black Research Institute, which is equipped with a flow control device in the blowing tank, which can evenly distribute magnesium particles and can adjust the flow of magnesium per unit time, but the feed adjustment valve complex structure

China Jiuquan Iron and Steel Co., Ltd. injection passivation magnesium feeding system, such as the patent application with publication number CN1239741A, utilizes traditional fluidized powder spraying equipment to adjust the auxiliary blowing N 2 Pressure, powder spray tank N 2 The pressure and its difference can realize the control of gas flow and magnesium particle flow, but the feeding amount and feeding speed cannot be precisely controlled, the feeding speed is uneven, the consumption of magnesium particles is relatively high, and the desulfurization reaction splashes large

[0004] In the existing desulfurization process, due to the strong desulfurization reaction, molten iron and desulfurization slag are prone to splashing. To prevent splashing, an anti-splash fume hood is set above the molten iron tank. The fume hood is made of refractory materials and splashes out. The slag and molten iron are easy to adhere to the fume hood and need to be cleaned regularly, and the adhesion layer is thick and difficult to clean, resulting in increased production costs and slow production rhythms

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