Method for rapidly removing P and Cr from alternating-current electric arc furnace

Abstract

The invention discloses a method for rapidly removing P and Cr from an alternating-current electric arc furnace, and relates to the technical field of metallurgy. According to the method for rapidly removing P and Cr in the alternating-current electric arc furnace, collaborative optimization is conducted on the process and parameters in stages, the phosphorus content in the chromium-nickel pig iron can be efficiently and rapidly reduced to the extremely low level, meanwhile, the chromium element content is accurately controlled, and the technical standard requirements of 06Ni9DR steel grades are strictly met. According to the process, the nickel element is reserved to the maximum extent, the stability and reliability of mother liquor components are guaranteed, and the aim of replacing a traditional nickel plate and an imported nickel-iron material with chromium-nickel pig iron is smoothly achieved. According to the technical breakthrough, the alloying production cost of the 06Ni9DR steel grade is greatly reduced, and the market competitiveness and economic benefits of the product are enhanced. In addition, the application of the process obviously reduces the dephosphorization pressure of the converter in the subsequent process, so that the phosphorus content control in the converter link is more accurate and stable.

Description

Technical Field

[0001] This application belongs to the field of metallurgical technology, and in particular relates to a method for rapid removal of P and Cr in an AC electric arc furnace. Background Technology

[0002] 06Ni9DR steel, as an important low-temperature steel, is widely used in many industrial fields, and its requirements for controlling residual chromium in molten steel are extremely strict. Traditionally, the nickel alloying raw materials for this steel grade mainly rely on high-value materials such as nickel plates and imported nickel iron, resulting in high alloy costs and seriously affecting the product's market competitiveness.

[0003] Chromium-nickel pig iron is a relatively inexpensive nickel-containing raw material. Its nickel content can meet the alloying requirements of 06Ni9DR steel. However, it has a high content of chromium and phosphorus, and its direct use will lead to substandard steel performance. Therefore, it has long been unable to be used in the smelting of this steel.

[0004] While existing technologies include processes for removing phosphorus and chromium using electric arc furnaces, they have several limitations: First, there is a lack of dedicated removal solutions for chromium-nickel pig iron, making it impossible to simultaneously achieve efficient removal of phosphorus and chromium while retaining nickel. Second, the lack of coordination in controlling parameters such as slag basicity, oxygen supply intensity, and temperature during the removal process leads to low removal efficiency, unstable reactions, and problems such as phosphorus reversion and incomplete chromium removal. Third, the processes cannot be adapted to the specific requirements of 06Ni9DR steel, making it difficult to provide qualified nickel alloying mother liquor. Summary of the Invention

[0005] To address some or all of the technical problems existing in the prior art, this application provides a method for rapid P and Cr removal in an AC electric arc furnace.

[0006] This application provides a method for rapid P and Cr removal in an AC electric arc furnace, comprising the following steps performed sequentially: Step S1: In the batching stage, chromium-nickel pig iron is added to the AC electric arc furnace as raw material, while the carbon and silicon content in the furnace are controlled. Step S2: Melting and desiliconization stage. The AC electric arc furnace melts the raw materials by supplying electricity, while controlling the slag basicity to ensure the slag fluidity. During this process, oxygen is supplied into the furnace to oxidize the carbon and phosphorus elements. The carbon monoxide gas generated by the carbon-oxygen reaction is used to stir the molten steel, while low-basicity desiliconization slag is discharged. Step S3: Rapid dephosphorization stage. When the power supply and oxygen supply reach the preset threshold, lime is added through the high-level silo to increase the slag basicity, and the oxygen supply flow is increased to enhance the slag oxidizing property, thereby rapidly removing phosphorus from the molten steel. Then the dephosphorized slag is discharged. Step S4: Enhanced dechromium removal stage. When the oxygen supply reaches the dechromium removal initiation threshold, the power supply is stopped, and the oxygen supply operation continues to increase the ferrous oxide content in the slag, thereby enhancing its oxidizing properties and removing residual chromium from the molten steel through oxidation. Step S5: During the tapping and slag removal stage, after sampling to confirm that the chromium and phosphorus content in the molten steel meets the standards, the tapping operation is carried out. After tapping, the slag is removed and the thickness of the slag left in the ladle is controlled to obtain the nickel alloying mother liquor.

[0007] Preferably, in step S1, the carbon content in the furnace is adjusted to 2.0-2.5%, and the silicon content is adjusted to 0.5-0.8%.

[0008] Preferably, in step S2, the slag basicity is controlled at 1.2-1.5; oxygen is supplied to the furnace after the power supply reaches 280-320 kWh / t, with an oxygen supply flow rate of 40-60 Nm³. 3 / min.

[0009] Preferably, in step S2, an oxygen lance can be used to supply oxygen to the AC electric arc furnace.

[0010] Preferably, in step S3, the preset thresholds for power supply and oxygen supply are: power supply reaching 420-450 kWh / t and oxygen supply reaching 6-8 Nm³. 3 / t.

[0011] Preferably, in step S3, after adding lime, the slag basicity is increased to 2.5-2.8, and the oxygen supply flow rate is increased to 60-100 Nm³. 3 The dephosphorization process is carried out at a temperature range of 1150-1550℃, and the dephosphorization slag is discharged after the phosphorus content of the molten steel drops to below 0.005%.

[0012] Preferably, in step S4, the initial threshold for chromium removal is when the oxygen supply reaches 17-20 Nm. 3 / t.

[0013] Preferably, in step S4, continuous oxygen supply increases the ferrous oxide content in the slag to 20-25%, and the oxygen supply reaches 30-35 Nm³. 3 After sampling and testing, chromium removal is completed when the chromium content of the molten steel is ≤0.15%.

[0014] Preferably, in step S5, the thickness of the slag left in the ladle after tapping is ≤50mm.

[0015] Preferably, the nickel alloying mother liquor is used as a nickel alloying raw material for 06Ni9DR steel.

[0016] The method for rapid P and Cr removal using an AC electric arc furnace in this application has the following advantages and positive effects: By optimizing the process and parameters in stages, the phosphorus content in chromium-nickel pig iron can be reduced to extremely low levels efficiently and rapidly, while precisely controlling the chromium content to strictly meet the technical standards of 06Ni9DR steel. This process not only retains nickel to the maximum extent, ensuring the stability and reliability of the mother liquor composition, but also successfully achieves the goal of replacing traditional nickel plates and imported nickel-iron materials with chromium-nickel pig iron. This technological breakthrough significantly reduces the alloying production cost of 06Ni9DR steel, enhancing the product's market competitiveness and economic benefits. Furthermore, the application of this process significantly reduces the dephosphorization pressure in subsequent converter processes, making phosphorus content control in the converter stage more precise and stable. Simultaneously, the improved reaction efficiency resulting from process optimization shortens the overall smelting cycle, further improving production efficiency. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0018] The method for rapid P and Cr removal using an AC electric arc furnace of this application includes the following steps performed sequentially: Step S1: In the batching stage, chromium-nickel pig iron is used as raw material, combined with auxiliary materials such as ferrosilicon and lime, and added to the AC electric arc furnace in batches through a charging basket. Simultaneously, the carbon and silicon content in the furnace is controlled; the carbon content is adjusted to 2.0-2.5%, and the silicon content to 0.5-0.8%, creating the necessary conditions for subsequent melting and oxidation removal reactions. Using inexpensive chromium-nickel pig iron to replace expensive nickel raw materials reduces costs from the source.

[0019] The carbon content of 2.0-2.5% provides sufficient raw materials for the carbon-oxygen reaction in the subsequent melting stage. At the same time, an appropriate amount of carbon can improve the fluidity of the molten steel, facilitating rapid melting of the raw materials and avoiding problems such as insufficient reactivity due to too low a carbon content, or excessive decarburization load due to too high a carbon content.

[0020] Silicon content 0.5-0.8%: As a deoxidizing element, silicon preferentially combines with oxygen in the molten steel during the melting stage, reducing harmful oxide inclusions. A silicon content of 0.5-0.8% can help adjust the slag composition, improve slag fluidity, and create favorable conditions for subsequent desiliconization and dephosphorization reactions. This avoids incomplete deoxidation due to excessively low silicon content, or increased difficulty in subsequent desiliconization due to excessively high content.

[0021] Step S2: Melting and Desiliconization Stage. The AC electric arc furnace melts the raw materials using electricity, while simultaneously controlling the slag basicity to ensure its fluidity. The slag basicity is controlled between 1.2 and 1.5. This basicity range ensures good slag fluidity, facilitating the smooth discharge of desiliconized slag and preventing slag agglomeration that could hinder the reaction. During this process, oxygen is supplied to the furnace to oxidize the carbon and phosphorus elements. Oxygen is supplied to the furnace after the electricity supply reaches 280-320 kWh / t, with an oxygen flow rate of 40-60 Nm³. 3 The carbon monoxide gas generated by the carbon-oxygen reaction is used to stir the molten steel at a rate of / min, ensuring uniform composition of the molten steel. At the same time, low-alkalinity desiliconization slag is discharged. The desiliconization slag enters the slag pot through the furnace door to avoid the accumulation of impurities affecting the subsequent desiliconization reaction. Specifically, oxygen can be supplied to the AC electric arc furnace using an oxygen lance, and the oxygen supply flow rate of the oxygen lance can be adjusted.

[0022] The power supply threshold of 280-320 kWh / t corresponds to the critical point where the raw materials are initially melted and a molten pool is formed. Starting oxygen supply at this time can ensure precise connection of the oxidation reaction, avoiding situations where the raw materials are not completely melted due to insufficient power supply, the reaction is too violent after oxygen supply, or energy waste and excessively high steel temperature due to excessive power supply.

[0023] Oxygen supply flow rate 40-60 Nm 3 The flow rate of 1000 m / min can meet the oxidation requirements of carbon and silicon elements, promote the heating and melting of molten steel, and avoid slow oxidation reaction and poor stirring effect due to too low a flow rate, or splashing of molten steel and increased energy consumption due to too high a flow rate, thus achieving a balance between oxidation efficiency and operational safety.

[0024] Step S3: Rapid dephosphorization stage. When the power supply and oxygen supply reach the preset thresholds, i.e., the preset thresholds are power supply reaching 420-450 kWh / t and oxygen supply reaching 6-8 Nm³. 3 / t, lime is added in batches and quantitatively through a high-level silo to increase the slag basicity. After adding lime, the slag basicity increases to 2.5-2.8, and the oxygen supply flow rate is increased to 60-100 Nm³. 3 The dephosphorization process is carried out at a rate of 1150-1550℃ to enhance the oxidizing properties of the slag and accelerate the oxidation of phosphorus, thereby quickly removing phosphorus from the molten steel. The dephosphorized slag is then discharged when the phosphorus content of the molten steel drops below 0.005%, effectively preventing the return of phosphorus caused by the increase in the temperature of the molten steel and ensuring a stable dephosphorization effect.

[0025] Among them, the power supply is 420-450 kWh / t, and the oxygen supply is 6-8 Nm³. 3The threshold values ​​of / t and t together indicate that the raw materials have been completely melted. Entering the dephosphorization stage at this point ensures that the reaction conditions are mature. Adequate power supply ensures that the molten steel temperature meets the dephosphorization requirements, while adequate oxygen supply ensures sufficient initial oxidation reaction, avoiding uneven dephosphorization due to incomplete melting.

[0026] High alkalinity is a key condition for dephosphorization. A slag alkalinity between 2.5 and 2.8 enhances the slag's adsorption capacity for phosphorus oxides, significantly improving dephosphorization efficiency. Simultaneously, it avoids incomplete dephosphorization due to excessively low alkalinity, or reduced slag fluidity and difficulty in slag discharge due to excessively high alkalinity.

[0027] Oxygen supply flow rate is 60-100 Nm 3 The flow rate is increased by 1 / min, which can rapidly improve the oxidizability of slag and accelerate the oxidation and removal of phosphorus, thus meeting the process goal of rapid dephosphorization. The flow rate adjustment range is precisely matched with the dephosphorization requirements to avoid slow dephosphorization due to insufficient flow rate or excessive oxidation of molten steel and loss of nickel due to excessive flow rate.

[0028] A temperature range of 1150-1550℃ can maximize the thermodynamic activity of the dephosphorization reaction and promote the transfer of phosphorus to the slag. At the same time, it can avoid the dephosphorization reaction from stopping due to excessively low temperature or the phosphorus from returning to the molten steel due to excessively high temperature, thus ensuring a stable dephosphorization effect.

[0029] Phosphorus content in molten steel ≤ 0.005%: This indicator is the core control target in the dephosphorization stage, ensuring that the phosphorus content in the molten steel meets the stringent requirements of the subsequent 06Ni9DR steel grade, reducing the subsequent dephosphorization load in the converter from the source, and avoiding product quality defects due to excessive phosphorus content.

[0030] Step S4: Enhanced dechromicing stage. Continue using the oxygen lance and slag pot; no additional equipment is needed. When the oxygen supply reaches the dechromicing initiation threshold, i.e., the oxygen supply reaches 17-20 Nm³, 3 / t, power supply is stopped to avoid excessive temperature affecting the dechromium removal reaction, while oxygen supply continues to increase the ferrous oxide content in the slag, thereby enhancing its oxidizing properties and removing residual chromium from the molten steel through oxidation; the ferrous oxide content in the slag is increased to 20-25%, and the oxygen supply reaches 30-35 Nm. 3 After sampling and testing, chromium removal is completed when the chromium content of the molten steel is ≤0.15%.

[0031] Among them, the oxygen supply is 17-20 Nm 3 / t represents the dechromium removal initiation threshold, corresponding to the point where the dephosphorization reaction is complete and the steel composition is stable. Initiating dechromium removal at this point avoids confusion in process connections. Adequate oxygen supply ensures a sufficient oxidizing atmosphere within the furnace, laying the foundation for subsequently increasing the ferrous oxide content and enhancing dechromium removal.

[0032] The ferrous oxide content in the slag should be between 20% and 25%. This range maximizes the oxidizing power of the slag, precisely oxidizing residual chromium in the molten steel, thus achieving efficient chromium removal. Simultaneously, it avoids incomplete chromium removal due to excessively low ferrous oxide content, or excessive oxidation of the molten steel and a decline in mechanical properties due to excessively high content.

[0033] Oxygen supply 30-35 Nm 3 / t is the detection threshold; this oxygen supply ensures the dechromium removal reaction proceeds fully. Sampling and testing at this threshold allows for accurate assessment of the dechromium removal effect, preventing insufficient oxygen supply from causing substandard chromium content or excessive oxygen supply from resulting in energy waste and fluctuations in molten steel composition.

[0034] Chromium content in molten steel ≤ 0.15%: This indicator directly meets the strict limit on residual chromium in 06Ni9DR steel, solves the industry pain point that chromium-nickel pig iron cannot be used due to excessive chromium content, and ensures the quality of nickel alloying mother liquor.

[0035] Step S5: During the tapping and slag removal stage, after sampling to confirm that the chromium and phosphorus content in the molten steel meets the standards, tapping is carried out. After tapping, slag is removed, and the slag thickness left in the ladle is controlled to be ≤50mm to obtain nickel alloying mother liquor. This avoids impurities in the slag from re-contaminating the mother liquor, ensuring its purity and providing high-quality raw materials for subsequent smelting in the converter. The nickel alloying mother liquor is used as the nickel alloying raw material for 06Ni9DR steel grade, added to the furnace for smelting 06Ni9DR, replacing nickel plates and imported nickel pig iron.

[0036] The technical solution of the present invention will be described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0037] Example 1: This embodiment uses an AC electric arc furnace for rapid P and Cr removal to prepare nickel alloying mother liquor for 06Ni9DR steel. The specific steps are as follows: Step S1: Ingredient preparation stage, the ingredients are as shown in Table 1 below; Table 1:

[0038] 86.5t of chromium-nickel pig iron was added into the AC electric arc furnace through a material basket. The electric arc furnace was started with power supply at level 4 for arc initiation. After the power supply reached 2523 kWh, it was increased to level 5, and 1717 kg of ferrosilicon and 2036 kg of lime were added simultaneously. When the power supply reached 29091 kWh, the power supply was stopped and a second batch of 80.85t of chromium-nickel pig iron was added. The power supply was continued for melting. After entering the well-cutting stage, 1017 kg of lime was added.

[0039] Step S2: Melting and desiliconization stage. When the power supply reaches 42135 kWh, oxygen blowing operation begins. The power supply level is reduced to level 3 to rapidly oxidize elements such as C and Si in the furnace, thereby increasing the furnace heating rate and material melting rate. During the oxygen blowing operation, the molten steel in the furnace is stirred by the decarburization reaction, and the low-basicity desiliconization slag in the furnace is released at the same time. The desiliconization slag is discharged into the slag pot, completing the desiliconization operation.

[0040] Step S3: Rapid dephosphorization stage, power supply up to 5805 kWh / t, oxygen supply up to 1215 Nm³. 3 After the desiliconization process is completed, the rapid dephosphorization phase begins, the power supply level is reduced to level 1, and the oxygen supply flow rate is increased to 80 Nm³. 3 / min, 2988 kg of lime was added in batches from the high-level silo, rapidly increasing the slag basicity to 2.5-2.8; power supply reached 77953 kWh and oxygen supply reached 2325 Nm³. 3 When the dephosphorization task is completed, the carbon content of the molten steel is less than 0.2%, and more than 80% of the dephosphorized slag in the furnace is discharged into the slag pot.

[0041] Step S4: Enhanced dechromiuming stage. After the dephosphorization stage is completed, power supply is stopped, and oxygen supply flow rate is increased to 100 Nm³. 3 / min, 2635Kg of lime was added in batches from the high-level silo, and oxygen blowing for chromium removal was carried out by enhancing the oxidizability of the slag through enhanced oxygen supply, with an oxygen supply of 3759Nm³. 3 Sampling confirmed that the residual Cr in the molten steel inside the furnace was 0.102% and P was 0.0013%.

[0042] Step S5: During the tapping and slag removal stage, after the composition of the molten steel in the furnace meets the standard, power is continued to heat the molten steel. Power is stopped when the power supply reaches 86979 kWh, and tapping is carried out. After tapping, the slag is removed using a slag removal device. The thickness of the slag left in the ladle is measured to be 40 mm, which meets the requirements. Nickel alloying mother liquor is obtained and transported to the converter for smelting 06Ni9DR steel.

[0043] Example 2: The process steps in this embodiment are the same as those in Embodiment 1, with only slight adjustments to the raw material loading amount, auxiliary material addition amount, and some power supply and oxygen supply parameters: Step S1: Ingredient preparation stage, the ingredients are as shown in Table 2 below; Table 2:

[0044] 85.3t of chromium-nickel pig iron was added into the AC electric arc furnace through a charging basket. The arc was started with power supply at level 4. When the power supply reached 3079 kWh, it was increased to level 5, and 1695 kg of ferrosilicon and 2042 kg of lime were added simultaneously. When the power supply reached 29875 kWh, the power supply was stopped and a second basket of 79.3t of chromium-nickel pig iron was added. The power supply was continued to melt the furnace. After entering the well-penetrating stage, 1135 kg of lime was added to ensure that the carbon and silicon content in the furnace was controlled within the preset range.

[0045] Step S2: Melting and desiliconization stage. When the power supply reaches 41986 kWh, oxygen blowing operation begins. The power supply level is reduced to level 3 to rapidly oxidize elements such as C and Si in the furnace, thereby increasing the furnace heating rate and material melting rate. During the oxygen blowing operation, the molten steel in the furnace is stirred by the decarburization reaction, and the low-basicity desiliconization slag in the furnace is released at the same time. The desiliconization slag is discharged into the slag pot, completing the desiliconization operation.

[0046] Step S3: Rapid dephosphorization stage, power generation reaches 56978 kWh / t, oxygen supply reaches 1209 Nm³. 3 After the desiliconization process is completed, the rapid dephosphorization phase begins, the power supply level is reduced to level 1, and the oxygen supply flow rate is increased to 80 Nm³. 3 / min, 3005 kg of lime was added in batches from the high-level silo to rapidly increase the slag basicity to 2.5-2.8; power supply reached 76938 kWh and oxygen supply reached 2298 Nm³. 3 When the dephosphorization task is completed, the carbon content of the molten steel is less than 0.2%, and more than 80% of the dephosphorized slag in the furnace is discharged into the slag pot.

[0047] Step S4: Enhanced dechromium removal stage. Power supply is stopped upon completion of the dephosphorization stage, and the oxygen supply flow rate is increased to 100 Nm³. 3 / min, 2575Kg of lime was added in batches from the high-level silo, and oxygen blowing for chromium removal was carried out by enhancing the oxidizability of the slag through enhanced oxygen supply, with an oxygen supply of 3819Nm³. 3 Sampling confirmed that the residual Cr in the molten steel in the furnace was 0.102% and P was 0.0009%.

[0048] Step S5: During the tapping and slag removal stage, after the composition of the molten steel in the furnace meets the standard, power is continued to heat the molten steel. Power is stopped when the power supply reaches 867882 kWh, and tapping is carried out. After tapping, the slag is removed using a slag removal device. The thickness of the slag left in the ladle is measured to be 50 mm, which meets the requirements. Nickel alloying mother liquor is obtained and transported to the converter for smelting 06Ni9DR steel.

[0049] Both embodiments have stable and smooth production processes, without problems such as phosphorus return or incomplete chromium removal. The produced nickel alloying mother liquor has high purity, fully meeting the smelting requirements of 06Ni9DR steel, and successfully realizing the substitution of nickel plates and imported nickel iron for chromium-nickel pig iron.

[0050] The technical solution presented in this application, through phased process and parameter coordination, can rapidly reduce the phosphorus content in chromium-nickel pig iron to extremely low levels, control the chromium content within the requirements of 06Ni9DR steel, and simultaneously retain nickel to the maximum extent, ensuring stable and reliable mother liquor quality. This achieves the substitution of chromium-nickel pig iron for nickel plates and imported nickel-iron, significantly reducing the alloying cost of 06Ni9DR steel and enhancing the product's market competitiveness. It also reduces the dephosphorization load in the converter, making phosphorus content control in the converter process more stable, while shortening the overall smelting cycle and improving production efficiency.

[0051] It should be noted that, unless otherwise expressly specified and limited, the term "connection" or its synonyms should be interpreted broadly in this document. For example, "connection" can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two elements or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. Furthermore, expressions such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. At the same time, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them; although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for rapid P and Cr removal in an AC electric arc furnace, characterized in that, The following steps are performed sequentially: Step S1: In the batching stage, chromium-nickel pig iron is added to the AC electric arc furnace as raw material, while the carbon and silicon content in the furnace are controlled. Step S2: Melting and desiliconization stage. The AC electric arc furnace melts the raw materials by supplying electricity, while controlling the slag basicity to ensure the slag fluidity. During this process, oxygen is supplied into the furnace to oxidize the carbon and phosphorus elements. The carbon monoxide gas generated by the carbon-oxygen reaction is used to stir the molten steel, while low-basicity desiliconization slag is discharged. Step S3: Rapid dephosphorization stage. When the power supply and oxygen supply reach the preset threshold, lime is added through the high-level silo to increase the slag basicity, and the oxygen supply flow is increased to enhance the slag oxidizing property, thereby rapidly removing phosphorus from the molten steel. Then the dephosphorized slag is discharged. Step S4: Enhanced dechromium removal stage. When the oxygen supply reaches the dechromium removal initiation threshold, the power supply is stopped, and the oxygen supply operation continues to increase the ferrous oxide content in the slag, thereby enhancing its oxidizing properties and removing residual chromium from the molten steel through oxidation. Step S5: During the tapping and slag removal stage, after sampling to confirm that the chromium and phosphorus content in the molten steel meets the standards, the tapping operation is carried out. After tapping, the slag is removed and the thickness of the slag left in the ladle is controlled to obtain the nickel alloying mother liquor.

2. The method for rapid P and Cr removal in an AC electric arc furnace according to claim 1, characterized in that, In step S1, the carbon content in the furnace is adjusted to 2.0-2.5%, and the silicon content is adjusted to 0.5-0.8%.

3. The method for rapid P and Cr removal in an AC electric arc furnace according to claim 1, characterized in that, In step S2, the slag basicity is controlled at 1.2-1.5; after the power supply reaches 280-320 kWh / t, oxygen is supplied into the furnace at a flow rate of 40-60 Nm³. 3 / min.

4. The method for rapid P and Cr removal in an AC electric arc furnace according to claim 3, characterized in that, In step S2, an oxygen lance can be used to supply oxygen to the AC electric arc furnace.

5. The method for rapid P and Cr removal in an AC electric arc furnace according to claim 1, characterized in that, In step S3, the preset thresholds for power supply and oxygen supply are: power supply reaching 420-450 kWh / t and oxygen supply reaching 6-8 Nm³. 3 / t.

6. The method for rapid P and Cr removal in an AC electric arc furnace according to claim 5, characterized in that, In step S3, after adding lime, the slag basicity is increased to 2.5-2.8, and the oxygen supply flow rate is increased to 60-100 Nm³. 3 The dephosphorization process is carried out at a temperature range of 1150-1550℃, and the dephosphorization slag is discharged after the phosphorus content of the molten steel drops to below 0.005%.

7. The method for rapid P and Cr removal in an AC electric arc furnace according to claim 1, characterized in that, In step S4, the initial threshold for chromium removal is when the oxygen supply reaches 17-20 Nm. 3 / t.

8. The method for rapid P and Cr removal in an AC electric arc furnace according to claim 7, characterized in that, In step S4, continuous oxygen supply increases the ferrous oxide content in the slag to 20-25%, and the oxygen supply reaches 30-35 Nm³. 3 After sampling and testing, chromium removal is completed when the chromium content of the molten steel is ≤0.15%.

9. The method for rapid P and Cr removal in an AC electric arc furnace according to claim 1, characterized in that, In step S5, the thickness of slag left in the ladle after tapping is ≤50mm.

10. The method for rapid P and Cr removal in an AC electric arc furnace according to any one of claims 1-9, characterized in that, The nickel alloying mother liquor is used as a nickel alloying raw material for 06Ni9DR steel.

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