Method for reducing nitrogen content of semi-steel steelmaking of converter

A nitrogen content, converter technology, applied in the field of metallurgy, can solve the problems of poor denitrification effect of RH vacuum treatment, nitrogen increase of molten steel, poor sealing effect, etc., and achieve good application prospects and promotion value

Active Publication Date: 2016-06-08
SICHUAN PAN YAN TECH
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  • Abstract
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Problems solved by technology

Therefore, it is more difficult to control the nitrogen content in molten steel during semi-steel smelting than in ordinary molten iron.
[0004] Converter smelting is one of the most effective means to remove nitrogen content in molten iron. RH vacuum treatment can also remove part of the nitrogen content when the nitrogen content in molten steel is high. Practice has proved that when the nitrogen content in molten steel is less than 35ppm The effect of nitrogen is very poor, and the nitrogen of molten steel is often increased due to the poor sealing effect of the vacuum device.

Method used

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  • Method for reducing nitrogen content of semi-steel steelmaking of converter

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Effect test

Embodiment 1

[0039] The 200t converter of a certain factory adopts semi-steel steelmaking, and the ratio of molten iron is controlled in converter smelting, and the ratio of molten iron is 0.9. Iron ore is added in the later stage of converter blowing, and the oxygen purity is greater than 99.7%; in the later stage of blowing, low gun position operation is adopted: Based on the oxygen blowing amount of the converter, when the oxygen blowing amount reaches 75% of the total oxygen amount, lower the position of the oxygen lance to 1-1.4m to avoid supplementary blowing out of the steel; 1000kg of small-grained lime for refining forms a layer of top slag on the molten steel surface. The thickness of the slag layer is less than 60mm, which effectively isolates the air and ensures a certain oxygen content in the molten steel to prevent nitrogen absorption. Add 400kg of top slag after tapping. Slag modifier; the taphole of the converter should be maintained frequently to keep the taphole in good co...

Embodiment 2

[0041] The 200t converter of a certain factory adopts semi-steel steelmaking, the converter smelting controls the molten iron ratio, the molten iron ratio is 0.91, and iron ore is added in the later stage of converter blowing, the oxygen purity, the mass fraction is greater than 99.8%; in the later stage of blowing, low gun position operation is adopted: Based on the oxygen blowing amount of the converter, when the oxygen blowing amount reaches 75% of the total oxygen amount, lower the position of the oxygen lance to 1-1.35m to avoid supplementary blowing out of the steel; 1010kg of small-grain lime for refining forms a layer of top slag on the molten steel surface. The thickness of the slag layer is less than 60mm, which effectively isolates the air and ensures a certain oxygen content in the molten steel to prevent nitrogen absorption. Add 410kg of top slag after tapping. Slag modifier; the taphole of the converter should be maintained frequently to keep the taphole in good c...

Embodiment 3

[0043]Converter smelting controls the molten iron ratio, the molten iron ratio is 0.95, and iron ore is added in the later stage of converter blowing, and the oxygen purity is greater than 99.9%; When the oxygen content reaches 75% of the total oxygen content, lower the position of the oxygen lance to 1-1.36m to avoid supplementary blowing out of the steel; when the steel is tapped to 2 / 3, put in dolomite, and at the same time add 1020kg of small-grained lime for refining, in the molten steel A layer of top slag is formed on the surface, and the thickness of the slag layer is less than 60mm, which effectively isolates the air and ensures a certain oxygen content in the molten steel to prevent nitrogen absorption. After tapping, add 420kg of top slag modifier; Frequent maintenance is required to maintain the state of the tapping hole and ensure that the tapping steel flow is round and does not diverge; after adopting these measures, the nitrogen blowing stop of the converter can...

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Abstract

The invention belongs to the technical field of metallurgy, in particular to a method for reducing the nitrogen content of semi-steel steelmaking of a converter. The method comprises the steps that a, the molten iron ratio of converter steelmaking is controlled to be higher than 0.9; b, in the later stage of blowing, low-lance-height operation is adopted, and the oxygen lance height is lowered till steel tapping is conducted when the oxygen blowing quantity reaches 70%-80% of the total oxygen quantity with the oxygen blowing quantity of the converter as the standard; C, when steel tapping is conducted by two thirds, dolomite is added, lime is added at the same time, a layer of top slag is formed on the molten steel surface, and the thickness of the slag layer is smaller than 60 mm; d, after steel tapping is completed, a top slag modifier is added; and e, a steel outlet is maintained, so that the effect that a steel outlet flow is not diffused is guaranteed. According to the method for reducing the nitrogen content of semi-steel steelmaking of the converter, the nitrogen content of discharged steel is controlled through converter steelmaking, so that the nitrogen content of the discharged steel is controlled within 15 ppm, and the demand for steel with high nitrogen-content requirement can be met. The method has good application prospects and high promotional value.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a method for reducing the nitrogen content of converter semi-steelmaking. Background technique [0002] For most steel types, nitrogen is a harmful element, and the nitrogen content in steel has a great influence on the mechanical properties of steel, especially when producing low-carbon and ultra-low-carbon steels used in deep drawing conditions, the adverse effects of nitrogen are particularly obvious. The increase of nitrogen content in steel will increase the yield limit, strength limit and hardness of steel, decrease plasticity, decrease impact toughness, and lead to age hardening. Nitrogen will also greatly increase the ductile-brittle transition temperature of steel, and may also cause low-temperature temper brittleness of steel, and some nitrides may also cause hot embrittlement of steel. Therefore, in the smelting of high value-added products such as hig...

Claims

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Application Information

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IPC IPC(8): C21C5/30
CPCC21C5/30
Inventor陈路曾建华陈均梁新腾张彦恒黄德胜
OwnerSICHUAN PAN YAN TECH