Method for preventing the return of sulfur after single-spray granular magnesium desulfurization in molten iron

Abstract

The invention discloses a method for preventing resulfurization of molten iron desulfurized through single blow grain magnesium. The method includes the steps that firstly, the temperature of a ladle is measured, pre-deslagging treatment is performed on molten iron after sampling is performed, and slagging materials are put into the molten iron; the amount of the blown magnesium is calculated, and the magnesium powder blowing process is performed; and after magnesium powder is blown, deslagging treatment is performed, and the molten iron is delivered out of a station after deslagging treatment. By the adoption of the method, the slagging materials including a calcium-based desulfurizing agent and refining slag are put into the molten iron, under the stirring effect of nitrogen and magnesium steam bubbles, high-alkalinity slag in the semi-molten state is formed on the surface of the molten iron, MgS products generated after magnesium desulfurization can be absorbed, incrustation is achieved as soon as blowing operation is finished, slag and iron are better separated, the slag is easy to scrabble, and the resulfurization phenomena are greatly reduced. By the adoption of the method, the technology is simple and feasible, desulfurization is stable, the resulfurization amount is small, the field process flow is modified conveniently, feasibility is high, and the method has the good application and popularization prospects in steel factories adopting the single blow grain desulfurization process.

Description

technical field [0001] The invention relates to a method for desulfurizing molten iron, in particular to a method for preventing resulfurization of molten iron after desulfurization by single-spraying granular magnesium. Background technique [0002] The main hot metal desulfurization methods in domestic and foreign steelmaking plants include CaO-magnesium powder composite injection, KR stirring method and single injection of granular magnesium. Because the desulfurization process of single-spray granular magnesium has strong desulfurization ability, small temperature drop, less slag, low iron loss, simple equipment, less investment and other advantages that other desulfurization methods cannot match, so this method is still widely used at home and abroad. The ratio is about 20%. The desulfurization process of single-injection granular magnesium desulfurization treatment is as follows: drive the desulfurization vehicle carrying molten iron to the injection position, measure...

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Problems solved by technology

However, the amount of slag formed in this desulfurization process is small, high in sulfur content, and thin. It is extremely difficult to remove the slag. The slag on the surface of the molten iron cannot fully absorb the desulfurization product magnesium sulfide, and this part of the slag with high sulfur content is carried along with the molten iron. During the smelting process of the converter, the high-sulfur slag returns to the molten iron, reaching an average of 0.016%, which has a serious impact on the smelting of low-sulfur steel, and cannot meet the production requirements of steel with a sulfur content of ≤0.020%

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