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Method for controlling nitrogen content in steel by semi-steel smelting

A nitrogen content, ladle technology, applied in the manufacture of converters, etc., can solve problems such as difficult nitrogen content, and achieve good promotion and application prospects

Inactive Publication Date: 2012-12-12
PANZHIHUA IRON AND STEEL +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, controlling the nitrogen content in molten steel during semi-steel smelting is more difficult than controlling the nitrogen content in molten iron

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] The semi-steel after vanadium extraction is used as raw material to smelt interstitial atom-free steel (IF steel), which requires the nitrogen content in the steel to be ≤25ppm.

[0025] After the semi-steel after vanadium extraction is pretreated by molten iron, the semi-steel is directly blended into the converter for smelting. The nominal capacity of the converter is 120t. The weight of the semi-steel into the furnace is 138.26t, the temperature is 1356°C, the carbon content is 3.76%, and the sulfur content is 0.005%. After detection and analysis, the nitrogen content of the semi-steel entering the furnace is 40ppm. After the semi-steel is mixed into the converter, the oxygen blowing smelting starts. At this time, the bottom blowing of the converter adopts the whole-process argon supply mode: the bottom of the converter is four breathable bricks, and the air supply flow rate of a single brick is 50Nm from the start of oxygen blowing to blowing for 11 minutes. 3 / h, ...

Embodiment 2

[0033] The 50PW800L steel is smelted with the vanadium-extracted semi-steel as the raw material, and the internal control of the finished product of this steel requires that the nitrogen content in the steel is ≤45ppm.

[0034] The semi-steel after vanadium extraction is pretreated by molten iron and then directly blended into the converter for smelting. The nominal capacity of the converter is 120t. The carbon content of the semi-steel into the furnace is 3.52%, the sulfur content is 0.006%, the weight of the semi-steel is 137.66t, and the temperature is 1369°C. After testing and analysis, the nitrogen content of the semi-steel into the furnace is 43ppm, and the oxygen blowing is started after the semi-steel is mixed into the converter . At this time, the bottom blowing of the converter adopts the mode of nitrogen supply in the early stage and argon supply in the later stage. Four breathable bricks are installed at the bottom of the converter, and the nitrogen flow rate of a ...

Embodiment 3

[0042] The semi-steel after vanadium extraction is used as raw material to smelt heavy rail steel, and the internal control of the finished steel product requires that the nitrogen content in the steel is ≤60ppm.

[0043] The semi-steel after vanadium extraction is pretreated by molten iron and then directly blended into the converter for smelting. The nominal capacity of the converter is 120t. The carbon content of the semi-steel into the furnace is 3.35%, the sulfur content is 0.003%, the weight of the semi-steel is 136.82t, and the temperature is 1368°C. After testing and analysis, the nitrogen content of the semi-steel into the furnace is 39ppm, and the oxygen blowing is started after the semi-steel is mixed into the converter . At this time, the bottom blowing of the converter adopts the mode of nitrogen supply in the early stage and argon supply in the later stage: six breathable bricks are installed at the bottom of the converter, and the nitrogen flow rate of a single ...

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Abstract

The invention discloses a method for controlling nitrogen content in steel by semi-steel smelting. According to the invention, the method for controlling nitrogen content in steel by semi-steel smelting comprises the following steps of: performing oxygen top blowing by using a converter, performing slag-modifying treatment before tapping, and blocking the slag and tapping. In addition, according to the requirements steel on nitrogen content, different bottom-blowing modes are adopted in the oxygen top blowing process by converter, a foaming agent is added at the last stage of blowing, argon gas is blown to ladles 1 to 3 minutes before tapping, and the soft argon blowing operation is performed on ladles during the tapping step. By adoption of the method provided by the invention, the nitrogen content in steel at the converter end-point can be controlled to be within 11 ppm and the nitrogen increase can be controlled to be between 1ppm to 3 ppm during the tapping step. The method provided by the invention can effectively reduce the nitrogen content at the converter end-point and the nitrogen increase in the tapping step, thereby providing a technical support for the production of low-nitrogen steel and ultra-low nitrogen steel.

Description

technical field [0001] The invention relates to the field of iron and steel metallurgy, in particular to a method for controlling nitrogen content in steel in semi-steel smelting. Background technique [0002] The nitrogen content in steel has a certain influence on the performance of steel. For most steel types, nitrogen will reduce the toughness and welding properties of steel, so it should be removed from steel as much as possible. Usually, in the pretreatment stage of molten iron, about 60% of nitrogen can be removed from molten iron by adding a denitrification agent composed of titanium slag and sodium carbonate, but the use of sodium carbonate will cause problems such as equipment corrosion, so it is rarely Use this method to remove nitrogen. In the secondary refining stage, the LF refining process increases nitrogen in the molten steel due to nitrogen decomposition in the arc zone, and the RH vacuum refining process can remove part of the nitrogen in the molten steel...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21C5/28C21C7/072
Inventor 陈均曾建华陈天明陈永梁新腾杨森祥李清春
Owner PANZHIHUA IRON AND STEEL
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