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Method for stably controlling oxidability of ultra-low carbon steel top slag

A stable control, ultra-low carbon steel technology, applied in the direction of manufacturing converters, etc., can solve the problems of the control of the tundish top slag oxidation, the influence of the top slag modification effect, and the lack of comprehensive consideration of the oxygen transfer in the steel. Achieve the effects of improving the pourability of molten steel, preventing mass transfer, and stabilizing oxidation

Active Publication Date: 2020-11-10
HANDAN IRON & STEEL GROUP +1
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  • Abstract
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  • Claims
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AI Technical Summary

Problems solved by technology

Although this process considers the influence of different processes on the top slag, it does not mention the oxygen transfer from molten steel to the top slag and the control of the top slag oxidation during the opening and closing of the ladle, which will also make the top slag modification effect affected
[0008] Scientific paper "The effect of 210tBOF-RH slab CC process ladle top slag modification treatment on ultra-low carbon steel inclusions": analyzed the influence of oxygen content in steel on FeO in slag, and pointed out the necessity of top slag modification However, no corresponding measures have been put forward to control the oxidative properties of tundish top slag during the pouring process.
[0009] It can be seen that in the existing ladle top slag modification measures, all of them focus on reducing the content of FeO and MnO in the top slag, and do not fully consider the transfer of oxygen in the steel to the top slag, as well as the increase in temperature by RH oxygen blowing or Oxygen in molten steel transfers to top slag during decarburization, and the influence of oxygen in the air on the oxidizability of top slag caused by the change of tundish liquid level during ladle replacement during continuous casting

Method used

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  • Method for stably controlling oxidability of ultra-low carbon steel top slag
  • Method for stably controlling oxidability of ultra-low carbon steel top slag
  • Method for stably controlling oxidability of ultra-low carbon steel top slag

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0055] (1) The final temperature of the converter for this heat is 1670°C, the carbon content at the final point is 0.05%, and the oxygen at the final point is 0.041%. During the tapping process of the converter, no deoxidizer and slagging material are added, and the ladle is not stirred with argon;

[0056] (2) after tapping finishes, the amount of slag under the ladle is 2.3t, and the TFe content is 18% in the converter slag, and the amount of steel tapping is 270t, calculate aluminum slag, lime addition according to formula 1, formula 2, be respectively 840kg, 570kg.

[0057] (3) After the converter is tapped, start blowing argon to stir at the bottom, the argon flow rate is 300L / min, start to add lime and aluminum slag, stop the bottom blowing and stir after feeding, so that the top slag modifier of the ladle is evenly spread in the The liquid level of the ladle, the oxygen content in the steel is reduced to 0.030% after modification;

[0058] (4) When RH blows oxygen to ...

Embodiment 2

[0063] (1) The final temperature of the converter for this furnace is 1675°C, the carbon content at the final point is 0.045%, and the oxygen at the final point is 0.045%. During the tapping process of the converter, no deoxidizer and slagging material are added, and the ladle is not stirred with argon;

[0064] (2) After tapping, the amount of slag discharged from the ladle is 2.2t, the TFe content in the converter slag is 18.5%, and the amount of tapping is 270t. According to Formula 1 and Formula 2, the amount of aluminum slag and lime added is calculated to be 885kg and 615kg respectively.

[0065] (3) After the converter is tapped, start blowing argon to stir at the bottom, the argon flow rate is 400L / min, start to add lime and aluminum slag, stop the bottom blowing and stir after feeding, so that the top slag modifier of the ladle is evenly spread in the Ladle liquid level, the oxygen content in the steel is reduced to 0.028% after modification;

[0066] (4) When RH blo...

Embodiment 3

[0071] (1) The end point temperature of the converter for this furnace is 1680°C, the end point carbon content is 0.025%, and the end point oxygen is 0.045%. No deoxidizer and slagging material are added during the tapping process of the converter, and the ladle is not turned on for argon stirring;

[0072] (2) After tapping, the amount of slag discharged from the ladle is 2.0t, the TFe content in the converter slag is 17.7%, and the amount of tapping is 270t. According to Formula 1 and Formula 2, the amount of aluminum slag and lime added is calculated to be 965kg and 690kg respectively.

[0073] (3) After the converter is tapped, start blowing argon to stir at the bottom, the argon flow rate is 450L / min, start to add lime and aluminum slag, stop the bottom blowing and stir after feeding, so that the top slag modifier of the ladle is evenly spread on the top of the ladle Ladle liquid level, the oxygen content in the steel is reduced to 0.026% after modification;

[0074] (4)...

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Abstract

The invention relates to a method for stably controlling the oxidability of ultra-low carbon steel top slag. The method comprises the following steps: S1, calculating the addition amounts of lime andan aluminum-based modifier according to the slag tapping amount and steel tapping amount of a converter, the TFe content in converter final slag and the oxygen content at the end point of the converter; S2, in the RH oxygen blowing temperature rising process, carrying out oxygen blowing and aluminum adding at the same time; S3, in the RH oxygen blowing decarburization process, controlling the oxygen blowing flow of a top lance to be 1,200-2,000 m<3> / h, so that the influence of sharp rising of oxygen in steel on the top slag is prevented; and S4, in the pouring process of a continuous casting machine, sealing a tundish, wherein the oxygen partial pressure in the tundish is controlled to be 0.3% or below. After the treatment measures are adopted, the content of TFe in the RH refining inlet steel ladle top slag can be stably reduced to 4% or below, the content of TFe in the RH refining outlet steel ladle top slag can be stably reduced to 6% or below, then the castability of molten steel is remarkably improved, the pouring service life of a single submerged nozzle can reach that of 6 furnaces or a longer time, and the total oxygen content of the tundish is reduced to 0.002% or below.

Description

technical field [0001] The invention relates to the technical field of ultra-low carbon steel smelting, in particular to a method for stably controlling the oxidative property of ultra-low carbon steel top slag. Background technique [0002] At present, the production of ultra-low carbon steel mainly adopts converter-RH vacuum refining-slab continuous casting process. Since reducing white slag cannot be produced without LF refining, the ladle top slag is still oxidative slag after the RH refining process, and the oxygen in FeO and MnO in the slag will be transported to the steel and be combined with [Al ] react to generate Al 2 o 3 Inclusions will pollute the molten steel, and even cause flocculation in severe cases. Therefore, it is necessary to modify the top slag of the ladle to reduce the oxidation of the top slag and reduce the number of inclusions in the steel. When Japan's Nippon Steel Corporation smelted ultra-low carbon steel, it was found that reducing the T Fe...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C5/36C21C7/10C21C7/068
CPCC21C5/36C21C7/068C21C7/10
Inventor 邓建军高福彬王新华李建文刘俊山汤海明唐笑宇曹晓恩
Owner HANDAN IRON & STEEL GROUP
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