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CN-122012868-A - Ladle top slag secondary modification method for smelting automobile plate steel

CN122012868ACN 122012868 ACN122012868 ACN 122012868ACN-122012868-A

Abstract

The application relates to a ladle top slag secondary modification method for smelting automobile plate steel, belonging to the technical field of steel smelting. The method comprises the steps of obtaining converter molten steel after converter blowing is finished, tapping the converter molten steel to a steel ladle, adding small lime into the converter molten steel in the steel ladle when the tapping amount reaches 1/3-1/2 of the total tapping amount in the converter molten steel tapping process, controlling the CaO/Al 2 O 3 ratio of top slag in the steel ladle to be 1.1-1.2, obtaining converter molten steel containing top slag, adding first aluminum slag balls into the converter molten steel containing top slag at the charging speed of less than or equal to 350kg/min after the converter molten steel tapping is finished, obtaining first modified molten steel, carrying out RH refining decarburization treatment on the first modified molten steel, obtaining decarburized molten steel, continuing RH refining on the decarburized molten steel, and adding second aluminum slag balls into the slag surface of the decarburized molten steel after the RH refining is finished, thus obtaining second modified molten steel.

Inventors

  • ZOU LEILEI
  • YANG XIAOSHAN
  • Hao Weizhe
  • WANG TONGHE
  • SHANG MINGYANG
  • WANG CHONG
  • GUAN SHUNKUAN
  • WANG SHENGDONG
  • DENG XIAOXUAN

Assignees

  • 首钢京唐钢铁联合有限责任公司

Dates

Publication Date
20260512
Application Date
20260209

Claims (10)

  1. 1. A ladle top slag secondary modification method for smelting automobile plate steel, which is characterized by comprising the following steps: after the converter blowing is finished, obtaining molten steel of the converter; Tapping the converter molten steel to a steel ladle, adding small lime into the converter molten steel in the steel ladle when the tapping amount reaches 1/3-1/2 of the total tapping amount in the tapping process of the converter molten steel, and controlling the CaO/Al 2 O 3 ratio of top slag in the steel ladle to be 1.1-1.2 to obtain converter molten steel containing top slag; After tapping of the converter molten steel is finished, adding first aluminum slag balls into the converter molten steel containing top slag at a charging speed less than or equal to 350kg/min to obtain first modified molten steel; Carrying out RH refining decarburization treatment on the first modified molten steel to obtain decarburized molten steel; And (3) continuously carrying out RH refining on the decarburized molten steel, and adding second aluminum slag balls into the slag surface of the decarburized molten steel after the RH refining is finished to obtain second modified molten steel.
  2. 2. The method of claim 1, wherein the converter molten steel has a temperature of 1660 ℃ to 1670 ℃ and an oxygen content of 300ppm to 500ppm.
  3. 3. The method of claim 1, wherein the tapping of the converter molten steel is performed by a slide plate front-back slag blocking technique, and the tapping of the converter molten steel has a slag tapping index <300.
  4. 4. The method of claim 1, wherein the mass of the first aluminum dross ball, a, satisfies a = 420+0.46 ([ O ] -163), wherein [ O ] represents the oxygen content of the converter molten steel and, if the unit of [ O ] is ppm, the unit of a is kg.
  5. 5. The method of claim 1, wherein the mass B of the second aluminum dross ball satisfies B = 591-TFe + 0.33- [ O ] C +59, wherein TFe represents the total iron content of the top dross in the first modified molten steel, O c represents the oxygen content in the decarbonized molten steel, and B is in kg if O c is in ppm.
  6. 6. The method of claim 1, wherein the first aluminum dross balls and the second aluminum dross balls each have a particle size of 20mm to 50mm, and the first aluminum dross balls and the second aluminum dross balls each comprise less than or equal to 8% Al 2 O 3 ：10%～20%,Al：50%～60%,CaF 2 ≤10%,CaCO 3 % by mass.
  7. 7. The method of claim 1, wherein the oxygen content in the first upgraded molten steel is 250ppm to 450ppm; And the oxygen content in the decarburized molten steel is 200 ppm-300 ppm.
  8. 8. The method of claim 1, wherein the alkalinity of the steel slag in the converter molten steel is 2.8-3.6, and the total iron content TFe of the steel slag in the converter molten steel is less than or equal to 20%; and the total iron content TFe of the top slag in the first modified molten steel is 1% -6%.
  9. 9. The method of claim 1, wherein the top slag in the second modified molten steel comprises, by mass, 35% -45% of CaO, 3% -6% of Al 2 O 3 ：30%～40%,SiO 2 %, 2% -8% of MgO, and 1% -6% of TFe.
  10. 10. The method according to claim 1, wherein the granularity of the small lime is 10 mm-30 mm, and the mass fraction of CaO in the small lime is >92%.

Description

Ladle top slag secondary modification method for smelting automobile plate steel Technical Field The application relates to the technical field of steel smelting, in particular to a ladle top slag secondary modification method for smelting automobile plate steel. Background In the production flow of the automobile sheet steel, the total iron content of the top slag of the steel ladle after the converter tapping is generally controlled to be 14% -20%, and the excessively high top slag TFe can enable secondary oxidation of molten steel to occur, so that Al 2O3 inclusion is generated, on one hand, a water gap is blocked, smooth continuous casting production is not facilitated, and on the other hand, the generated inclusion can be further transmitted to a subsequent rolling process, so that batch inclusion defects of the automobile sheet steel can occur. Therefore, in order to improve the cleanliness of the automobile plate steel, the ladle top slag needs to be sufficiently modified to control the reasonable and stable ladle top slag TFe. In the existing top slag modification process, lime is added only in the converter tapping process to adjust the CaO/Al 2O3 index and the fluidity of the top slag, so that the adsorption and inclusion capacity of the top slag is enhanced. Little attention is paid to the stability of the TFe of the top slag of the smelting whole-flow ladle and the influence of the TFe on the cleanliness of molten steel. Although measures for reducing the top slag TFe of the steel ladle by adding a deoxidizer after tapping of the converter are proposed, the lower top slag TFe requirement of the RH refining process cannot be maintained by one-time modification, and molten steel oxygen in the RH refining process can be continuously transferred to the top slag through a steel-slag interface so as to raise the TFe. Therefore, development of a ladle top slag secondary modification process is particularly urgent and necessary. Disclosure of Invention The application provides a ladle top slag secondary modification method for smelting automobile plate steel, which aims to solve the technical problem of how to reduce the total iron content of the whole-flow ladle top slag so as to improve the cleanliness of molten steel. The embodiment of the application provides a ladle top slag secondary modification method for smelting automobile plate steel, which comprises the following steps: after the converter blowing is finished, obtaining molten steel of the converter; Tapping the converter molten steel to a steel ladle, adding small lime into the converter molten steel in the steel ladle when the tapping amount reaches 1/3-1/2 of the total tapping amount in the tapping process of the converter molten steel, and controlling the CaO/Al 2O3 ratio of top slag in the steel ladle to be 1.1-1.2 to obtain converter molten steel containing top slag; After tapping of the converter molten steel is finished, adding first aluminum slag balls into the converter molten steel containing top slag at a charging speed less than or equal to 350kg/min to obtain first modified molten steel; Carrying out RH refining decarburization treatment on the first modified molten steel to obtain decarburized molten steel; And (3) continuously carrying out RH refining on the decarburized molten steel, and adding second aluminum slag balls into the slag surface of the decarburized molten steel after the RH refining is finished to obtain second modified molten steel. Optionally, the temperature of the converter molten steel is 1660-1670 ℃, and the oxygen content of the converter molten steel is 300-500 ppm. Optionally, the steel tapping of the converter adopts a slide plate front-back slag blocking technology, and the slag discharging index of the steel tapping of the converter is less than 300. Optionally, the mass A of the first aluminum slag balls meets the condition that A=420+0.46 DEG ([ O ] -163), wherein [ O ] represents the oxygen content in the converter molten steel, and if the unit of [ O ] is ppm, the unit of A is kg. Optionally, the mass B of the second aluminum slag ball meets the requirement that B=591.TFe+0.33.O C +59, wherein TFe represents the total iron content of the top slag in the first modified molten steel, O c represents the oxygen content in the decarburized molten steel, and B is kg if O c is in ppm. Optionally, the granularity of the first aluminum slag ball and the granularity of the second aluminum slag ball are 20-50 mm, and the components of the first aluminum slag ball and the second aluminum slag ball comprise less than or equal to 8% of Al 2O3：10%～20%,Al：50%～60%,CaF2≤10%,CaCO3 in percentage by mass. Optionally, the oxygen content in the first modified molten steel is 250ppm to 450ppm. Optionally, the oxygen content in the decarburized molten steel is 200ppm to 300ppm. Optionally, the alkalinity of the steel slag in the converter molten steel is 2.8-3.6, and the total iron content TFe of the steel slag in the c