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CN-122012864-A - Method for rapidly removing P and Cr in alternating current arc furnace

CN122012864ACN 122012864 ACN122012864 ACN 122012864ACN-122012864-A

Abstract

The application discloses a method for rapidly removing P and Cr in an alternating current arc furnace, and relates to the technical field of metallurgy. According to the method for rapidly removing P and Cr in the alternating current arc furnace, the process and parameters are cooperatively optimized in stages, so that the phosphorus content in the chromium-nickel pig iron can be efficiently and rapidly reduced to an extremely low level, and meanwhile, the content of chromium is accurately controlled, so that the method strictly meets the technical standard requirements of 06Ni9DR steel grades. The process not only reserves nickel element to the greatest extent, ensures the stability and the reliability of the components of the mother liquor, but also smoothly achieves the aim of replacing the traditional nickel plate and imported nickel iron material by chromium-nickel pig iron. The technological break-through greatly reduces the alloying production cost of 06Ni9DR steel grade, and enhances the market competitiveness and economic benefit of the product. In addition, the dephosphorization pressure of the converter in the subsequent process is obviously reduced by the application of the process, so that the phosphorus content in the converter link is controlled more accurately and stably.

Inventors

  • WANG SHUXIANG
  • HOU HAIBIN
  • ZHAO JUNYI
  • DUAN JIANFENG
  • Yue Houlai
  • ZHANG BIN
  • LIANG JUNJUN
  • ZHANG SHIEN

Assignees

  • 山西太钢不锈钢股份有限公司

Dates

Publication Date
20260512
Application Date
20260205

Claims (10)

  1. 1. The method for rapidly removing P and Cr in the alternating current arc furnace is characterized by comprising the following steps in sequence: step S1, in the burdening stage, chromium-nickel pig iron is taken as a raw material to be added into an alternating current arc furnace, and the carbon content and the silicon content in the furnace are regulated and controlled at the same time; in the process, oxygen is supplied to the furnace to oxidize carbon and phosphorus elements in the furnace, and carbon monoxide gas generated by carbon-oxygen reaction is utilized to stir molten steel, and meanwhile, low-alkalinity desilication slag is discharged; S3, in a rapid dephosphorization stage, when the power supply and the oxygen supply reach preset thresholds, lime is added through a high-level bin to improve the alkalinity of slag, and meanwhile, the oxygen supply flow is increased to strengthen the oxidizing property of the slag, so that phosphorus elements in molten steel are rapidly removed, and then dephosphorization slag is discharged; S4, in the reinforced chromium removal stage, when the oxygen supply reaches a chromium removal initial threshold value, stopping power supply, continuously performing oxygen supply operation, and increasing the content of ferrous oxide in slag so as to enhance the oxidability of the slag, and further removing residual chromium element in molten steel through oxidation; and S5, in the tapping and slag skimming stage, sampling is performed to confirm that the chromium and phosphorus content in the molten steel reach the standard, tapping operation is performed, slag skimming is performed after tapping, and the thickness of slag left in the ladle is controlled, so that the nickel alloying mother liquor is obtained.
  2. 2. The method for rapid P and Cr removal in an AC arc furnace according to claim 1, wherein in the step S1, the carbon content in the furnace is controlled to be 2.0-2.5% and the silicon content is controlled to be 0.5-0.8%.
  3. 3. The method for rapidly removing P and Cr in an AC arc furnace according to claim 1, wherein in the step S2, the alkalinity of slag is controlled to be 1.2-1.5, and oxygen is supplied to the furnace after the power supply amount reaches 280-320Kwh/t, and the oxygen supply flow is 40-60Nm 3 /min.
  4. 4. The method for rapid P and Cr removal in an AC arc furnace according to claim 3, wherein in step S2, oxygen is supplied to the AC arc furnace by using an oxygen lance.
  5. 5. The method for rapid P and Cr removal in an AC arc furnace according to claim 1, wherein in the step S3, the preset threshold values of the power supply and the oxygen supply are 420-450Kwh/t and 6-8Nm 3 /t.
  6. 6. The method for rapid P and Cr removal in an AC arc furnace according to claim 5, wherein in step S3, the slag alkalinity is raised to 2.5-2.8 after lime is added, the oxygen supply flow is raised to 60-100Nm 3 /min, the dephosphorization process is carried out in the temperature range of 1150-1550 ℃, and the dephosphorization slag is discharged after the molten steel phosphorus content is reduced to below 0.005%.
  7. 7. The method for rapid P-and Cr-removal in an AC arc furnace according to claim 1, wherein the starting threshold for the chromium removal in step S4 is that the oxygen supply reaches 17-20Nm 3 /t.
  8. 8. The method for rapid P and Cr removal in an AC arc furnace according to claim 7, wherein in the step S4, oxygen is continuously supplied to raise the ferrous oxide content in the slag to 20-25%, sampling and detecting are carried out after the oxygen supply reaches 30-35Nm 3 /t, and the chromium removal is completed when the chromium content in the molten steel is less than or equal to 0.15%.
  9. 9. The method for rapidly removing P and Cr in an AC arc furnace according to claim 1, wherein in the step S5, the thickness of the slag remained in the slag removed ladle after tapping is less than or equal to 50mm.
  10. 10. The method for rapid P-and Cr-removal in an ac electric arc furnace according to any one of claims 1 to 9, wherein the nickel alloy mother liquor is used as a nickel alloy raw material for 06Ni9DR steel grades.

Description

Method for rapidly removing P and Cr in alternating current arc furnace Technical Field The application belongs to the technical field of metallurgy, and particularly relates to a method for rapidly removing P and Cr in an alternating current arc furnace. Background The 06Ni9DR steel is used as an important low-temperature steel, has wide application in various industrial fields, and has extremely strict control requirement on residual chromium element in molten steel. When the steel is smelted conventionally, the nickel alloying raw materials mainly depend on high-value materials such as nickel plates, imported ferronickel and the like, so that the alloy cost is high, and the market competitiveness of the product is seriously affected. Chromium-nickel pig iron is used as a relatively cheap nickel-containing raw material, the nickel content of the chromium-nickel pig iron can meet the alloying requirement of 06Ni9DR steel grade, but the direct use of the chromium element and the phosphorus element can cause the steel grade performance to be substandard, so the chromium-nickel pig iron cannot be applied to smelting of the steel grade for a long time. In the prior art, although the related processes of P and Cr removal of an electric arc furnace exist, the technology has a plurality of limitations that firstly, a special removal scheme for chromium-nickel pig iron is lacked, high-efficiency removal of phosphorus and chromium and retention of nickel elements cannot be considered, secondly, parameters such as slag alkalinity, oxygen supply strength, temperature and the like are regulated and controlled in a removal process, so that the problems of low removal efficiency, unstable reaction, easy occurrence of phosphorus element return, incomplete chromium element removal and the like are caused, thirdly, the technology cannot be adapted to the specific requirements of 06Ni9DR steel types, and qualified nickel alloying mother liquor is difficult to provide. Disclosure of Invention In order to solve part or all of the technical problems in the prior art, the application provides a method for rapidly removing P and Cr in an alternating current arc furnace. The application provides a method for rapidly removing P and Cr in an alternating current arc furnace, which comprises the following steps in sequence: step S1, in the burdening stage, chromium-nickel pig iron is taken as a raw material to be added into an alternating current arc furnace, and the carbon content and the silicon content in the furnace are regulated and controlled at the same time; in the process, oxygen is supplied to the furnace to oxidize carbon and phosphorus elements in the furnace, and carbon monoxide gas generated by carbon-oxygen reaction is utilized to stir molten steel, and meanwhile, low-alkalinity desilication slag is discharged; S3, in a rapid dephosphorization stage, when the power supply and the oxygen supply reach preset thresholds, lime is added through a high-level bin to improve the alkalinity of slag, and meanwhile, the oxygen supply flow is increased to strengthen the oxidizing property of the slag, so that phosphorus elements in molten steel are rapidly removed, and then dephosphorization slag is discharged; S4, in the reinforced chromium removal stage, when the oxygen supply reaches a chromium removal initial threshold value, stopping power supply, continuously performing oxygen supply operation, and increasing the content of ferrous oxide in slag so as to enhance the oxidability of the slag, and further removing residual chromium element in molten steel through oxidation; and S5, in the tapping and slag skimming stage, sampling is performed to confirm that the chromium and phosphorus content in the molten steel reach the standard, tapping operation is performed, slag skimming is performed after tapping, and the thickness of slag left in the ladle is controlled, so that the nickel alloying mother liquor is obtained. Preferably, in the step S1, the carbon content in the furnace is regulated to be 2.0-2.5%, and the silicon content is regulated to be 0.5-0.8%. Preferably, in the step S2, the alkalinity of the slag is controlled to be 1.2-1.5, and oxygen is supplied to the furnace after the power supply amount reaches 280-320Kwh/t, and the oxygen supply flow is 40-60Nm 3/min. Preferably, in step S2, oxygen is supplied to the ac arc furnace by using an oxygen lance. Preferably, in the step S3, the preset threshold values of the power supply amount and the oxygen supply amount are that the power supply amount reaches 420-450Kwh/t and the oxygen supply amount reaches 6-8Nm 3/t. Preferably, in the step S3, the alkalinity of slag is raised to 2.5-2.8 after lime is added, the oxygen supply flow is raised to 60-100Nm 3/min, the dephosphorization process is carried out in the temperature range of 1150-1550 ℃, and the dephosphorization slag is discharged after the phosphorus content of molten steel is reduced to below 0.005%. Preferably, i