Method for preventing resulfurization of molten iron after desulfurization treatment

Abstract

In processes for manufacturing molten steel from molten pig iron by performing, on desulfurized molten pig iron, a subsequent step of decarburization refining, etc., the present invention prevents resulfurization arising from microscopic desulfurization slag suspended in the molten pig iron or desulfurization slag adhering to the side walls of the processing vessel that is generated during desulfurization of the molten pig iron. This method for preventing resulfurization of molten pig iron after desulfurization: performs desulfurization of molten pig iron inside a processing vessel using a mechanical stirring desulfurization apparatus; then blows inert gas into the molten pig iron from gas-jetting holes (6) set in the impeller (4) of the mechanical stirring desulfurization apparatus and stirs the molten pig iron (3); floats the desulfurization slag suspended in the molten pig iron and / or desulfurization slag adhering to the inner walls of the processing vessel up to the surface of the molten pig iron by said stirring; discharges the floating desulfurization slag from the processing vessel; and subsequently conveys the molten pig iron inside the processing vessel to the next step.

Description

technical field [0001] The present invention relates to the prevention of residues generated during the desulfurization treatment of molten iron and suspended in molten iron after treatment in the process of smelting molten steel from molten iron such as decarburization refining in the next step after desulfurization treatment. A method for re-sulfurization caused by desulfurization slag in the treatment vessel. Background technique [0002] In recent years, the ratio of ultra-low-sulfur and / or ultra-low-phosphorus steel grades has increased due to the increasing demand for high-purity and high-functionalization of steel materials. Under such circumstances, in the steelmaking process, there is a need for a technology for melting ultra-low-sulfur and / or ultra-low-phosphorus steel grades without causing an increase in cost, an increase in the amount of slag generated, and the like. [0003] In the case of smelting low-sulfur steel, ultra-low-sulfur steel, etc., desulfurizatio...

AI Technical Summary

Problems solved by technology

[0013] That is, no technology has been proposed to promote the floating and separation of fine desulfurization slag suspended in molten iron after desulfurization treatment, and to prevent resulfurization of molten iron after desulfurization treatment.

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