Method for preparing magnesium-based desulfurizing agent

Abstract

The invention discloses a method for preparing a magnesium-based desulfurizing agent in the iron and steel smelting process. The method comprises the following steps of: a, preparing a modifier, namely, stirring and mixing calcined dolomite powder, silicon calcium alloy powder and fluorspar powder according to a mass ratio of the calcined dolomite powder to the silicon calcium alloy powder to the fluorspar powder of 6:1:3, and after mixing, briquetting the dry powder and pelleting, wherein the grain diameter is 1.0 to 1.6 mm; b, preparing coating magnesium grains, namely, preparing solution according to a mass ratio of crystalline magnesium chloride to boric acid to water of 1:0.1:100, adding the solution which accounts for 8 percent of the weight of the magnesium grains into the magnesium grains to stir, then adding the roasted dolomite powder which accounts for 2 percent of the weight of the magnesium grains into the magnesium grains to stir at a low speed, and heating and drying to make water content less than 0.5 percent; c, adding the modifier which accounts for 5 to 7 percent of the mass of the coating magnesium grains into the coating magnesium grains to mix uniformly; d, cooling and then packaging; and e, putting the finished products in a storehouse. The magnesium-based desulfurizing agent prepared by the method has the advantages of avoiding excessive powder materials in the desulfurizing agent, increasing flowability, stabilizing the blowing speed and the reaction, avoiding a gun blocking phenomenon, saving the using amount of the raw material magnesium during use and reducing the production cost of the conventional magnesium-based desulfurizing agent.

Description

technical field [0001] The invention belongs to the technical field of desulfurizer additives in iron and steel smelting, and in particular relates to a preparation method of a magnesium-based desulfurizer. Background technique [0002] With the improvement of market requirements for steel performance, the use of fast desulfurization and deep desulfurization materials has become a necessary prerequisite for the production of low S, P steel or ultra-low S, P steel. As an efficient and fast desulfurization material, magnesium-based desulfurizer has been selected by most iron and steel enterprises in the late 1990s. my country's Wuhan Iron and Steel, Baosteel, Taiyuan Iron and Steel and other enterprises took the lead in establishing desulfurization stations, using mixed injection of magnesium particles or single blowing of coated particles of magnesium to remove S. Due to the low melting point and boiling point of magnesium (651°C and 1107°C), adding magnesium bubbles to the ...

AI Technical Summary

Problems solved by technology

Due to the low melting point and boiling point of magnesium (651°C and 1107°C), adding magnesium bubbles to the molten iron can stir the molten iron, but the high vapor pressure of magnesium (0.63MPa at 1350°C) will produce explosive reactions when added to molten iron, resulting in spraying. Therefore, it is generally used to add certain additives, commonly used to make a 90% mixture of AL2O3, CaO, and CaF2, but there are many powders, which affect the fluidity, and the speed will be unstable and the gun will be blocked during the injection.

For this reason, manufacturers of S-removing agents adopt the method of coating magnesium granules with halogen salt. The product does not contain powder, which not only reduces the reaction speed (that is, increases the flame retardant time), but also increases the fluidity of the product. It is difficult to achieve the Mg content required by users (about 92%)

Generally, Mg is 96%. In order to achieve the target of 92%, the proportion of the brine salt solution is increased to react the surface of the Mg particles in a boiling state, resulting in a waste of expensive material magnesium, and a large amount of brine salt components affect the impurities in the molten iron. Removal of debris and ballast, the ballast formed during the desulfurization process cannot be separated from the molten iron well, and sticks to the inner wall of the spray gun gasification chamber, the speed is very fast, usually about 20 times to clean once, the ballast also contains condensed molten iron, which is very difficult to clean Disaster

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