Refining method for producing stainless steel by VOD (vacuum oxygen decarburization) blowing CO2

Abstract

The invention discloses a refining method for producing stainless steel by vacuum oxygen decarburization (VOD) blowing CO2. The method is characterized in that CO2 gas is blown into molten steel in a VOD refining process. The method comprises that: the bottom blowing gas is CO2 after the smelted primary molten steel is carried into a VOD, the blowing strength is 0.1 to 0.5Nm<3> / min.t, and then the pure oxygen is blown by adopting a top oxygen lance till the carbon content is less than 0.5 percent, wherein the blowing strength of the O2 is 2.5 to 3.0Nm<3> / min.t; the pure oxygen is blown by adopting the top oxygen lance, wherein the blowing strength of the O2 is 2.0 to 2.3Nm<3> / min.t; when the carbon content is less than 0.1 percent, the mixed gas of the O2 and the CO2 is blown by adopting the top oxygen lance, wherein the blowing strength of the O2 is 2.0 to 2.3Nm<3> / min.t, and the blowing strength of the CO2 is 1.8 to 2.0Nm<3> / min.t; and when the carbon content reaches a target lower limit, silicon-iron alloy is added to perform reduction and alloying treatment, and the top oxygen lance stops working till steel is tapped, wherein the bottom blowing gas is Ar, and the blowing strength of the Ar is 0.1 to 0.5Nm<3> / min.t. The problems of high dissolved oxygen content of refining end point molten steel and high oxidation in slag are solved, the consumption of alloy is reduced at the same time, and the method has remarkable economic benefit and social benefit by using the CO2 for decarburization.

Description

technical field [0001] The invention belongs to the field of out-of-furnace refining of iron and steel metallurgical technology, in particular to a VOD injection CO 2 Refining method for producing low carbon steel. Background technique [0002] VOD refining equipment is one of the main equipment for producing stainless steel. The basic principle of refining is to blow oxygen and decarburize molten steel under vacuum conditions, which is used to refine low-carbon or very low-carbon stainless steel. Originally, this process only blows oxygen at the top, and the chromium in the molten steel is seriously oxidized after the carbon content drops below 0.5%, resulting in an increase in the use of reduced alloys in the later stage. Secondly, due to the use of oxygen for decarburization, the dissolved oxygen content in the molten steel at the end of refining and the oxidative property in the slag are relatively high, resulting in a large amount of deoxidized alloys and high costs. ...

AI Technical Summary

Problems solved by technology

Originally, this process only blows oxygen at the top, and the chromium in the molten steel is seriously oxidized after the carbon content drops below 0.5%, resulting in an increase in the use of reduced alloys in the later stage.

Secondly, due to the use of oxygen for decarburization, the dissolved oxygen content in the molten steel at the end of refining and the oxidative property in the slag are relatively high, resulting in a large amount of deoxidized alloys and high costs

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