Method for smelting 300-series stainless steel based on high-phosphorus nickel pig iron cold charge

Abstract

The invention relates to a method for smelting 300-series stainless steel based on high-phosphorus nickel pig iron cold charge, and belongs to the technical field of stainless steel smelting. Comprising the following steps that S1, high-phosphorus molten nickel iron melted by an alloy melting furnace is blended into a pre-dissolving tank; s2, a top spraying dephosphorization device is used for conducting desiliconization pretreatment on the high-phosphorus molten nickel iron; s3, performing dephosphorization treatment on the high-phosphorus molten nickel iron by using a top spraying dephosphorization device; s4, the pre-dissolving tank bearing the dephosphorized molten nickel iron is conveyed to a molten chromium iron alloy melting furnace to be mixed with molten chromium iron; and S5, the stainless steel pre-dissolving solution in the pre-dissolving tank is mixed into an AOD furnace for stainless steel refining treatment. According to the method, the top spraying dephosphorization device is used for dephosphorization treatment of the high-phosphorus nickel molten iron melted by the alloy melting furnace, so that the requirement for the phosphorus content of the charging raw material of the AOD furnace is met. The low-cost high-phosphorus nickel pig iron can be adopted as the raw material in the process of duplex smelting of the 300-series stainless steel by the alloy melting furnace and the AOD furnace. And meanwhile, the top spraying dephosphorization device is used for carrying out desiliconization pretreatment on the high-phosphorus nickel molten iron, so that the content of silicon entering the AOD furnace is reduced, and the operation conditions of the AOD furnace are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of stainless steel smelting, and relates to a method for smelting 300 series stainless steel based on high-phosphorus nickel pig iron cold material. Background Art

[0002] In the pursuit of continuously reducing the cost per ton of steel and to further improve metal yield in the smelting process, a process has been developed through production practice that uses an all-alloy melting furnace to melt alloys, replacing electric furnaces for smelting 300 series stainless steel. All ferrochrome and ferronickel used in this process are melted in an alloy melting furnace. The stainless steel pre-solution melted in the alloy melting furnace is then added to an AOD furnace for stainless steel refining. When producing 300 series stainless steel using all-cold material, the production cost of the all-alloy melting furnace → AOD furnace route is lower than the electric furnace + alloy melting furnace → AOD furnace route, which is lower than the electric furnace → AOD furnace route. For example, using 304 stainless steel as an example, the all-alloy melting furnace → AOD furnace route costs approximately 325 yuan per ton less than the electric furnace → AOD furnace route, given the same raw material conditions.

[0003] The advantages of the all-alloy melting furnace → AOD furnace process are as follows: 1) All metal raw materials are melted in the alloy melting furnace. Since the alloy melting furnace does not require oxygen blowing, the metal yield can reach 99%, improving the yields of nickel, chromium, and iron. 2) Due to the increased carbon and silicon content of the AOD furnace input, the AOD furnace provides sufficient heat, allowing most of the cold ferrochrome to be added at the AOD furnace stage, further improving the overall ferrochrome yield. However, the lack of oxygen blowing in the alloy melting furnace also has disadvantages for this process. Since the alloy melting furnace has no metallurgical function and cannot dephosphorize, the production of 300 series, especially low-phosphorus 300 series, requires controlling the phosphorus content of the raw materials, especially the phosphorus content in nickel pig iron, which is used in the largest quantities.

[0004] In summary, in order to solve the shortcomings of the alloy melting furnace → AOD furnace process in the production of 300 series stainless steel using high-phosphorus nickel pig iron as the main raw material, it is urgent to propose a new smelting method that can further reduce the production cost of 300 series stainless steel smelting while meeting the endpoint phosphorus content requirements of 300 series products. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a method for smelting 300 series stainless steel based on cold high-phosphorus nickel pig iron. The method adds a top spray dephosphorization device between the alloy melting furnace and the AOD furnace. The top spray dephosphorization device is used to pre-desiliconize and dephosphorize the high-phosphorus nickel molten iron melt melted in the alloy melting furnace to meet the phosphorus content requirements of the raw materials entering the AOD furnace, and then meet the phosphorus content requirements of the final product. At the same time, because the top spray dephosphorization device pre-desiliconizes the high-phosphorus nickel molten iron, the silicon content of the AOD furnace entering the furnace is reduced, thereby improving the operating conditions of the AOD furnace.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The method for smelting 300 series stainless steel based on high phosphorus nickel pig iron cold material includes the following steps:

[0008] S1. Add high-phosphorus nickel iron water: add the high-phosphorus nickel iron water melted in the alloy melting furnace into the pre-dissolving tank;

[0009] S2. Desiliconization pretreatment: The high-phosphorus nickel-iron water in the pre-dissolving tank is subjected to desiliconization pretreatment using a top-spray dephosphorization device, and desiliconization slag is separated after the desiliconization pretreatment;

[0010] S3, dephosphorization treatment: the high-phosphorus nickel iron water in the pre-dissolved tank is dephosphorized by the top spray dephosphorization device, and the dephosphorization slag is separated after the dephosphorization is completed;

[0011] S4, adding chromium iron water: transporting the pre-melting tank carrying the dephosphorized nickel iron water to the chromium iron alloy melting furnace to add chromium iron water to form a stainless steel pre-solution;

[0012] S5. Stainless steel refining: The stainless steel pre-solution in the pre-dissolving tank is added into the AOD furnace for stainless steel refining treatment to form stainless steel.

[0013] Optionally, according to the method for smelting 300 series stainless steel based on high-phosphorus nickel pig iron cold material of the present invention, the high-phosphorus nickel molten iron and the chromium molten iron are melted separately in independent alloy melting furnaces.

[0014] Optionally, according to the method for smelting 300 series stainless steel based on high-phosphorus nickel pig iron cold material described in the present invention, the raw material of the high-phosphorus nickel molten iron is high-phosphorus nickel pig iron, and the composition of the high-phosphorus nickel pig iron is C=1.5~4.0%, Si≤2.5%, P≥0.1%, S≤0.15%, Ni=10~12%, and the balance is iron.

[0015] Optionally, according to the method for smelting 300 series stainless steel based on high-phosphorus nickel pig iron cold material described in the present invention, the raw material of the molten chromium iron is high-carbon ferrochrome, and the composition of the high-carbon ferrochrome is C=6.0~8.0%, Si=4.0~5.0%, P≤0.03%, S≤0.03%, Cr=49.0~52.0%, and the balance is iron.

[0016] Optionally, according to the method for smelting 300 series stainless steel based on high-phosphorus nickel pig iron cold material described in the present invention, in step S2, material iron oxide scale is added to the pre-dissolution tank, a premix of lime and fluorite is sprayed into the pre-dissolution tank using a powder spray gun, and oxygen is blown into the pre-dissolution tank through an oxygen gun.

[0017] Optionally, according to the method for smelting 300 series stainless steel based on high-phosphorus nickel pig iron cold material of the present invention, the silicon content in the high-phosphorus nickel iron water after desiliconization pretreatment is ≤0.15%.

[0018] Optionally, according to the method for smelting 300 series stainless steel based on high-phosphorus nickel pig iron cold material described in the present invention, in step S3, a premix of lime and fluorite is sprayed into the pre-dissolution tank using a powder spray gun, and oxygen is blown into the pre-dissolution tank through an oxygen gun to assist.

[0019] Optionally, according to the method for smelting 300 series stainless steel based on high-phosphorus nickel pig iron cold material of the present invention, the phosphorus content in the dephosphorized nickel iron water after dephosphorization treatment is ≤0.04%.

[0020] Optionally, according to the method for smelting 300 series stainless steel based on high-phosphorus nickel pig iron cold material of the present invention, the activity of lime in the premix of lime and fluorite is ≥350, and the CaO content in the lime is ≥90%.

[0021] Optionally, according to the method for smelting 300 series stainless steel based on high-phosphorus nickel pig iron cold material of the present invention, in step S5, the stainless steel pre-solution directly added to the AOD furnace is 700-900 kg / t steel, and the remaining raw materials are added to the AOD furnace in the form of cold material.

[0022] The beneficial effects of the present invention are:

[0023] The present invention uses high-phosphorus nickel pig iron and high-carbon ferrochrome as main raw materials, and realizes cost reduction and efficiency improvement through reconstruction of raw material pretreatment system and coordinated optimization of process. High-phosphorus nickel pig iron and high-carbon ferrochrome are smelted in special melting furnaces respectively to avoid the phosphorus brought into high-phosphorus nickel pig iron from being difficult to remove due to the high chromium content of the solution; most of the metal raw materials (including scrap steel, nickel-chromium intermediate alloy, etc.) are melted and cleared in the alloy melting furnace in advance, and the metal yield is increased to 99% by using an oxygen-free melting environment (oxygen-free operation), which is 3-5 percentage points higher than the traditional electric arc furnace process, and realizes efficient capture of nickel, chromium and iron elements. A top-spray dephosphorization device is added between the alloy melting furnace and the AOD furnace, and the high-phosphorus nickel iron water melted in the alloy melting furnace is desiliconized and dephosphorized by the top-spray dephosphorization device to meet the phosphorus content requirements of the raw materials entering the AOD furnace, and then meet the phosphorus content requirements of the product end point. At the same time, since the top-spray dephosphorization device performs desiliconization pretreatment on the high-phosphorus nickel iron water, the silicon content entering the AOD furnace is reduced, and the operating conditions of the AOD furnace are improved.

[0024] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0026] Figure 1 This is a schematic diagram of the process flow of the method for smelting 300 series stainless steel based on high-phosphorus nickel pig iron cold material provided by the present invention.

[0027] Figure numerals: 1- nickel-iron melting alloy melting furnace; 2- pre-melting tank; 3- top spray dephosphorization device; 4- chromium-iron melting alloy melting furnace; 5- AOD furnace; 6- molten steel tank. DETAILED DESCRIPTION

[0028] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0029] Among them, the accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting the present invention. In order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the dimensions of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings.

[0030] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc. indicating directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0031] See also Figure 1 The figure shows a process flow diagram of a method for smelting 300 series stainless steel based on high phosphorus nickel pig iron cold material.

[0032] The equipment used in this process includes a nickel-iron alloy melting furnace 1, which is used for high-temperature melting of high-phosphorus nickel-iron water.

[0033] The pre-dissolving tank 2 is used to receive high-phosphorus nickel iron water as a container for desiliconization and dephosphorization treatment of the high-phosphorus nickel iron water, and to receive chromium iron water to achieve mixing of stainless steel pre-dissolving solution.

[0034] The top spray dephosphorization device 3 is used for desiliconization pretreatment and dephosphorization treatment of high-phosphorus nickel iron water.

[0035] The ferrochrome melting alloy melting furnace 4 is used for high-temperature melting of molten ferrochrome.

[0036] AOD furnace 5 is used for refining of stainless steel.

[0037] The molten steel tank 6 adds the refined stainless steel solution into the molten steel tank and transports it to the subsequent process to form a stainless steel product.

[0038] Specifically, the method includes the following steps:

[0039] S1. Adding high-phosphorus nickel iron water: adding the high-phosphorus nickel iron water melted in the alloy melting furnace 1 into the pre-dissolving tank 2.

[0040] S2. Desiliconization pretreatment: The high-phosphorus nickel-iron water in the pre-dissolving tank 2 is subjected to desiliconization pretreatment by using the top-spray dephosphorization device 3, and desiliconization slag is separated after the desiliconization pretreatment.

[0041] S3, dephosphorization treatment: the high-phosphorus nickel iron water in the pre-dissolution tank 2 is dephosphorized by the top spray dephosphorization device 3, and the dephosphorization slag is separated after the dephosphorization is completed.

[0042] S4, adding chromium iron water: transporting the pre-melting tank 2 carrying the dephosphorized nickel iron water to the chromium iron alloy melting furnace 4 to add chromium iron water to form a stainless steel pre-solution.

[0043] S5, stainless steel refining: the stainless steel pre-solution in the pre-dissolution tank 2 is added to the AOD furnace 5 for stainless steel refining treatment to form stainless steel.

[0044] The present invention uses high-phosphorus nickel pig iron and high-carbon ferrochrome as main raw materials, and realizes cost reduction and efficiency improvement through reconstruction of raw material pretreatment system and coordinated optimization of process. Most of the metal raw materials (including scrap steel, nickel-chromium master alloy, etc.) are melted and cleared in the alloy melting furnace in advance, and the metal yield is increased to 99% by using an oxygen-free smelting environment (oxygen-free operation), which is 3-5 percentage points higher than the traditional electric arc furnace process, and the efficient capture of nickel, chromium and iron elements is achieved. A top spray dephosphorization device 3 is added between the alloy melting furnace 1 and the AOD furnace 5, and the high-phosphorus nickel iron water melted in the alloy melting furnace is desiliconized and dephosphorized by the top spray dephosphorization device 3 to meet the phosphorus content requirements of the raw materials entering the AOD furnace 5, and then meet the phosphorus content requirements of the product terminal. At the same time, since the top spray dephosphorization device 3 carries out desiliconization pretreatment on the high-phosphorus nickel iron water, the silicon content of the AOD furnace 5 entering the furnace is reduced, and the operating conditions of the AOD furnace 5 are improved. Based on the market price in 2023, the price difference between high-phosphorus nickel pig iron containing 10% nickel and low-phosphorus nickel pig iron is about 1,500 to 2,000 yuan per ton. Taking 304 stainless steel as an example, the alloy melting furnace-AOD furnace dual process uses high-phosphorus nickel pig iron to reduce the cost of using low-phosphorus nickel pig iron by 700 to 1,000 yuan per ton of steel, which has considerable economic value. Although the present invention adds a top-spray dephosphorization link, the cost of the top-spray dephosphorization process per ton of steel is less than 100 yuan. After deducting the cost of the top-spray dephosphorization process, the comprehensive cost of the whole process is still competitive.

[0045] Furthermore, the high-phosphorus nickel pig iron and molten ferrochrome are melted separately in separate alloy melting furnaces. The high-phosphorus nickel pig iron and high-carbon ferrochrome are smelted in separate, dedicated melting furnaces to prevent phosphorus introduced into the high-phosphorus nickel pig iron from being difficult to remove due to the high chromium content in the solution.

[0046] Furthermore, the raw material of high-phosphorus nickel iron water is high-phosphorus nickel pig iron, and the composition of high-phosphorus nickel pig iron is C=1.5~4.0%, Si≤2.5%, P≥0.1%, S≤0.15%, Ni=10~12%, and the balance is iron.

[0047] Nickel pig iron (NPI) containing 10-12% nickel is widely used as the nickel-containing raw material for 300 series stainless steel. Nickel plates or nickel beans are used for fine-tuning the composition. The carbon and silicon in the NPI oxidize in the AOD furnace to provide heat, increasing the AOD furnace's cold charge ratio. Phosphorus and sulfur are harmful elements. While sulfur can be removed in the AOD process, the chromium in stainless steel can affect phosphorus removal from the molten steel. Therefore, phosphorus must be removed from the raw material to the required phosphorus content before entering the AOD furnace.

[0048] The high-phosphorus nickel pig iron of the present invention breaks through the phosphorus content limit of nickel-iron raw materials in the alloy melting furnace-AOD furnace smelting process by reconstructing the raw material pretreatment system and co-optimizing the process steps, thereby achieving the goal of further optimizing costs.

[0049] Furthermore, the raw material of the molten ferrochrome is high carbon ferrochrome, and the composition of the high carbon ferrochrome is C=6.0-8.0%, Si=4.0-5.0%, P≤0.03%, S≤0.03%, Cr=49.0-52.0%, and the balance is iron.

[0050] High-carbon ferrochrome, with its high chromium content, low phosphorus and sulfur content, and synergistic ferrosilicon content, is widely used as an ideal raw material for stainless steel and alloy steel production. High-carbon ferrochrome provides chromium and iron to stainless steel. The carbon and silicon in the raw material oxidize in the AOD furnace, providing heat and increasing the cold charge ratio.

[0051] Furthermore, in step S2, iron oxide scale is added to the pre-dissolution tank 2, a premix of lime and fluorite is sprayed into the pre-dissolution tank 2 using a powder spray gun, and oxygen is blown into the pre-dissolution tank 2 through an oxygen gun.

[0052] In step S3, a premix of lime and fluorite is sprayed into the pre-dissolution tank 2 by using a powder spray gun, and oxygen is blown into the pre-dissolution tank 2 by using an oxygen gun.

[0053] Furthermore, the silicon content in the high-phosphorus nickel iron water after desiliconization pretreatment is ≤0.15%.

[0054] Furthermore, the phosphorus content in the dephosphorized nickel-iron water after dephosphorization treatment is ≤0.04%.

[0055] Specifically:

[0056] Before dephosphorizing molten iron, certain silicon content requirements are met. To reduce dephosphorization agent consumption, control slag volume, and ensure operational stability, pre-desiliconization of the molten iron is required. The top-spray dephosphorization unit 3 uses iron oxide and oxygen as silicon oxidizers and injects a premix of lime and fluorite for slag conditioning, ensuring efficient desiliconization, reduced iron loss, and stable operation.

[0057] When the silicon content of the molten iron is ≤0.15%, the dephosphorization requirements are met. After removing the desiliconization slag, oxygen blowing and powder spraying are used for dephosphorization. Depending on the final phosphorus requirement of the steel grade, the phosphorus content of the nickel-iron molten iron is reduced to below 0.04%. For low-phosphorus 300 series steel, the phosphorus content of the nickel-iron molten iron needs to be reduced to below 0.01%. After dephosphorization, the dephosphorization slag is removed to prevent rephosphorization.

[0058] Furthermore, the activity of lime in the premix of lime and fluorite is ≥350, and the CaO content in the lime is ≥90%.

[0059] Lime with activity ≥350 has high specific surface area (>1.5m 2 / g) and a loose porous structure, which can quickly dissolve and release Ca when in contact with the molten pool. 2+ , shortening the slag phase formation time.

[0060] High CaO content (≥90%) reduces the dilution of the effective activity of CaO by impurities (such as SiO2 and MgO), ensures sufficient free CaO concentration in the slag, directly improves the binding efficiency of phosphorus oxidation products (P2O5) and CaO, forms stable 3CaO·P2O5 or 4CaO·P2O5, and improves the dephosphorization reaction rate constant (k).

[0061] The fluorite in the premix accelerates the dissolution of lime, reduces the viscosity of the slag phase, promotes mass transfer at the slag-metal interface, and increases the distribution ratio of phosphorus in the slag.

[0062] Highly active lime increases the slag formation rate and lime utilization, reduces the injection dephosphorization cycle, reduces the slag volume and increases the metal recovery rate.

[0063] Furthermore, in step S5 , the stainless steel pre-solution directly added to the AOD furnace 5 is 700-900 kg / t steel, and the remaining raw materials are added to the AOD furnace 5 in the form of cold materials.

[0064] The stainless steel pre-solution is directly added to the AOD furnace 5. The pre-solution temperature is approximately 1300-1450°C. In addition to carrying a large amount of sensible heat, the carbon and silicon in the pre-solution can be oxidized in the AOD furnace to provide heat, thereby increasing the AOD furnace's cold charge ratio. The AOD furnace refines the stainless steel pre-solution, removes silicon and carbon, adjusts its composition, desulfurizes, and reduces it, ultimately smelting it into qualified molten steel.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for smelting 300 series stainless steel based on cold high-phosphorus nickel pig iron, characterized by: The following steps are involved: S1. Add high-phosphorus nickel iron water: add the high-phosphorus nickel iron water melted in the alloy melting furnace into the pre-dissolving tank; S2. Desiliconization pretreatment: The high-phosphorus nickel-iron water in the pre-dissolving tank is subjected to desiliconization pretreatment using a top-spray dephosphorization device, and desiliconization slag is separated after the desiliconization pretreatment; S3, dephosphorization treatment: the high-phosphorus nickel iron water in the pre-dissolved tank is dephosphorized by the top spray dephosphorization device, and the dephosphorization slag is separated after the dephosphorization is completed; S4, adding chromium iron water: transporting the pre-melting tank carrying the dephosphorized nickel iron water to the chromium iron alloy melting furnace to add chromium iron water to form a stainless steel pre-solution; S5. Stainless steel refining: The stainless steel pre-solution in the pre-dissolving tank is added into the AOD furnace for stainless steel refining treatment to form stainless steel.

2. The method for smelting 300 series stainless steel based on high-phosphorus nickel pig iron cold material according to claim 1, characterized in that: The high-phosphorus nickel iron water and the chromium iron water are melted separately in mutually independent alloy melting furnaces.

3. The method for smelting 300 series stainless steel based on high-phosphorus nickel pig iron cold material according to claim 2, characterized in that: The raw material of the high-phosphorus nickel iron water is high-phosphorus nickel pig iron, and the composition of the high-phosphorus nickel pig iron is C=1.5-4.0%, Si≤2.5%, P≥0.1%, S≤0.15%, Ni=10-12%, and the balance is iron.

4. The method for smelting 300 series stainless steel based on high-phosphorus nickel pig iron cold material according to claim 2, characterized in that: The raw material of the molten chromium iron is high-carbon ferrochrome, and the composition of the high-carbon ferrochrome is C=6.0-8.0%, Si=4.0-5.0%, P≤0.03%, S≤0.03%, Cr=49.0-52.0%, and the balance is iron.

5. The method for smelting 300 series stainless steel based on high phosphorus nickel pig iron cold material according to claim 1, characterized in that: In step S2, iron oxide scale is added to the pre-dissolution tank, a premix of lime and fluorite is sprayed into the pre-dissolution tank using a powder spray gun, and oxygen is blown into the pre-dissolution tank through an oxygen gun.

6. The method for smelting 300 series stainless steel based on high-phosphorus nickel pig iron cold material according to claim 5, characterized in that: The silicon content in the high-phosphorus nickel-iron water after desiliconization pretreatment is ≤0.15%.

7. The method for smelting 300 series stainless steel based on high phosphorus nickel pig iron cold material according to claim 1, characterized in that: In step S3, a premix of lime and fluorite is sprayed into the pre-dissolution tank using a powder spray gun, and oxygen is blown into the pre-dissolution tank through an oxygen gun.

8. The method for smelting 300 series stainless steel based on high-phosphorus nickel pig iron cold material according to claim 7, characterized in that: The phosphorus content in the dephosphorized nickel-iron water after dephosphorization treatment is ≤0.04%.

9. The method for smelting 300 series stainless steel based on high-phosphorus nickel pig iron cold material according to claim 5 or 7, characterized in that: The activity of lime in the premix of lime and fluorite is ≥350, and the CaO content in the lime is ≥90%.

10. The method for smelting 300 series stainless steel based on high phosphorus nickel pig iron cold material according to claim 1, characterized in that: In step S5, the amount of stainless steel pre-solution directly added to the AOD furnace is 700-900 kg / t steel, and the remaining raw materials are added to the AOD furnace in the form of cold materials.

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