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Secondary refining method for improving molten steel cleanliness

A secondary refining and cleanliness technology, applied in the secondary refining field of molten steel, which can solve problems such as fire and explosion accidents, complicated processes, and poor hydrogen safety.

Active Publication Date: 2017-01-04
ANGANG STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] To sum up, in the secondary refining process of molten steel, the removal of inclusions carried by air bubbles is the main method, and for this process, how to generate small air bubbles is the key. In the prior art, the stability of RH powder spraying and tundish blowing technology Poor, complex process, difficult
RH injection of hydrogen is less safe. Hydrogen is a low-density gas. When the proportion in air is 13%-59%, it will form an explosive mixed gas. Once hydrogen leaks, hydrogen will spread rapidly and easily cause fire and explosion. ACCIDENT

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Steel Type: Low Carbon Aluminum Killed Steel

[0023] Process route: converter-argon station-RH-continuous casting.

[0024] Specific steps:

[0025] The weight of the molten steel is 253t. After the converter is tapped, the temperature of the molten steel hanging in the tank is 1635°C, and the bottom blowing argon treatment is carried out in the argon station. Use an industrial humidifier to humidify the argon gas. After humidification, use a dew point meter to detect that the moisture content in the argon gas is 50%.

[0026] The molten steel is subjected to RH treatment, the lifting gas is argon, and the lifting gas is humidified at the initial stage of the RH treatment. The lifting gas flow rate is 120Nm3 / h. The gas was changed to conventional argon, and the entire RH treatment time was 25min.

[0027] The ladle enters the casting platform, and the molten steel enters the crystallizer through the tundish and is cast into billets.

[0028] Compared with the origi...

Embodiment 2

[0032] Steel Type: Pipeline Steel

[0033] Process route: converter-LF-RH-continuous casting

[0034] Specific steps:

[0035] The weight of the molten steel is 105t. After the converter is tapped, it is moved to the LF treatment station. The temperature of the molten steel LF entering the station is 1575°C. During the LF process, the molten steel is treated with bottom blowing argon gas stirring. Use an industrial humidifier to humidify the argon gas. After humidification, use a moisture analyzer to detect that the moisture content in the argon gas is 45%. Argon is not humidified, and the treatment time of the whole process is 70 minutes. When the molten steel is moved out of the LF processing station, it is detected that the hydrogen content of the molten steel is 0.0025%.

[0036] The molten steel is subjected to VD treatment, the pressure holding vacuum degree is 67Pa, and the pressure holding time is 22 minutes.

[0037] The ladle enters the casting platform, and the ...

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Abstract

The invention discloses a secondary refining method for improving molten steel cleanliness. After molten steel obtained through converter tapping enters a ladle, the molten steel is subjected to gas blowing stirring with the gas blowing amount being 1-5 NL / min.t; firstly, the moisture content of gas is detected, and then the gas is humidified to enable the moisture content of the gas to be 10%-50%; the gas blowing time is 15-50 min, the hydrogen content of the molten steel is detected after gas blowing, and it is guaranteed that the hydrogen content of the molten steel is 0.0005%-0.0025%; and the molten steel is subjected to vacuum treatment for 15-30 min, and then temperature measurement, oxygen determination, hydrogen determination and tapping are conducted.

Description

technical field [0001] The invention belongs to the technical field of secondary refining of molten steel, in particular to a secondary refining method for improving the cleanliness of molten steel. Background technique [0002] Clean steel means that the number, size and distribution of non-metallic inclusions in steel have no effect on the performance of steel. Improving the cleanliness level of steel is mainly aimed at harmful inclusions in steel. The main work is to reduce the inclusions. Quantity and size, improving the distribution of inclusions to reduce the hazards of inclusions. In the steelmaking-continuous casting production process, the removal of molten steel inclusions is mainly in the secondary refining, tundish and crystallizer. [0003] Secondary refining is considered to be the most important process for purifying molten steel. At present, secondary refining devices for molten steel represented by RH, LF, VD, and CAS-OB are widely used in steel production....

Claims

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Application Information

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IPC IPC(8): C21C7/10C21C7/072
Inventor 廖相巍赵成林常桂华张宁黄玉平
Owner ANGANG STEEL CO LTD
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