A method for smelting steel with limestone

Abstract

This application relates to the technical field of steelmaking, and more particularly to a method for smelting steel using limestone. The method comprises: determining the total amount of limestone to be added based on the Si content in the chemical composition of molten iron, and adding the limestone in corresponding amounts in stages; mixing the limestone added in the first stage with molten iron and scrap steel to produce raw steelmaking materials; blowing the raw steelmaking materials, and adding the remaining limestone in corresponding amounts in the remaining stages to produce molten steel. This application addresses the technical issue of achieving efficient dephosphorization in existing steelmaking processes using limestone instead of lime.

Description

Technical Field

[0001] The present application relates to the technical field of steelmaking, and in particular to a method for smelting steel from limestone. Background Art

[0002] Lime is the primary slag-forming raw material in converter steelmaking, ensuring efficient dephosphorization. Reducing converter lime consumption is an ongoing effort within the industry to lower steelmaking costs. Replacing some lime in slag production with limestone can reduce converter lime consumption to a certain extent.

[0003] However, the traditional limestone steelmaking process can only replace a small amount of lime. When a steel plant encounters a temporary shortage of lime, using traditional limestone instead of lime steelmaking process cannot achieve efficient dephosphorization, and the smelting of low-phosphorus steel varieties is severely restricted. Summary of the Invention

[0004] The present application provides a method for smelting steel using limestone to solve the technical problem that it is difficult to achieve efficient dephosphorization in the existing process of smelting steel using limestone instead of lime.

[0005] In a first aspect, the present application provides a method for smelting steel from limestone, the method comprising:

[0006] According to the Si content in the chemical composition of the molten iron, the total amount of limestone to be added is determined, and the limestone is added in stages according to the corresponding addition amount; wherein,

[0007] Mixing the limestone added in the first stage amount with molten iron and scrap steel to obtain steelmaking raw materials;

[0008] The steelmaking raw materials are blown, and the remaining limestone is added in a corresponding amount in the remaining stages to obtain molten steel.

[0009] Optionally, the Si content and the total amount of limestone added W satisfy the following relationship:

[0010] W=(23+50*w (Si) ).γ

[0011] Where w (Si) represents the Si content, γ represents the correction coefficient, and W represents the total amount of limestone added;

[0012] If the Si content in molten iron is ≤0.3 wt%, γ = 1;

[0013] If the Si content in molten iron is 0.3 wt% < ≤ 0.4 wt%, γ = 1.3;

[0014] If the Si content in molten iron is 0.4 wt% < ≤ 0.5 wt%, γ = 1.5;

[0015] If the Si content in molten iron is 0.5 wt% < ≤ 0.6 wt%, γ = 1.7;

[0016] If Si in molten iron is greater than 0.6 wt%, γ=2.

[0017] Optionally, the amount added in the first stage is W*50%.

[0018] Optionally, the steelmaking raw materials are blown and the remaining limestone is added in a corresponding amount in the remaining stages to obtain molten steel, comprising:

[0019] The steelmaking raw materials are blown, and the remaining limestone is added in a corresponding amount according to the oxygen blowing ratio in the remaining stage to obtain molten steel; wherein,

[0020] When the oxygen blowing ratio is 6%, the limestone having the second stage addition amount is added; wherein the second stage addition amount is W*30%.

[0021] Optionally, the steelmaking raw materials are blown and the remaining limestone is added in a corresponding amount in the remaining stages to obtain molten steel, comprising:

[0022] The steelmaking raw materials are blown, and the remaining limestone is added in a corresponding amount according to the oxygen blowing ratio in the remaining stage to obtain molten steel; wherein,

[0023] When the oxygen blowing ratio is 22%-25%, the limestone having the third stage addition amount is added; wherein the third stage addition amount is W*20%.

[0024] Optionally, the content of the scrap steel is ≤10% by weight.

[0025] Optionally, the steelmaking raw materials are blown and the remaining limestone is added in a corresponding amount in the remaining stages to obtain molten steel, comprising:

[0026] The steelmaking raw materials are blown, and the remaining limestone is added in corresponding amounts in the remaining stages according to the oxygen blowing ratio, and the addition amounts of lime, light-burned dolomite and ore are controlled in stages to obtain molten steel.

[0027] Optionally, the steelmaking raw materials are blown.

[0028] The remaining limestone is added in corresponding amounts in the remaining stages according to the oxygen blowing ratio, and the addition amounts of lime, light-burned dolomite and ore are controlled in stages to obtain molten steel, comprising:

[0029] The steelmaking raw materials are blown, and the remaining limestone is added in corresponding amounts in the remaining stages according to the oxygen blowing ratio, and the addition amounts of lime, light-burned dolomite and ore are controlled in stages to obtain molten steel; wherein,

[0030] When the oxygen blowing ratio is 6%, the limestone having the second-stage addition amount is added, the second-stage addition amount is W*30%, the first-stage addition amount of the lime is 4kg / t-4.5kg / t, the first-stage addition amount of the light-burned dolomite is 4kg / t-4.5kg / t, and the first-stage addition amount of the ore is M*55%-M*60%;

[0031] When the oxygen blowing ratio is 22%-25%, the limestone having the third-stage addition amount is added, the third-stage addition amount is W*20%, the second-stage addition amount of the lime is 4kg / t-4.5kg / t, the second-stage addition amount of the light-burned dolomite is 9kg / t-10kg / t, and the second-stage addition amount of the ore is M*20%-M*30%;

[0032] When the oxygen blowing ratio is 80%, the amount of ore added in the third stage is M*10%-M*20%; wherein M represents the total amount of ore added.

[0033] Optionally, when the oxygen blowing ratio is 80%, the amount of ore added in the third stage is M*10%-M*20%; wherein M represents the total amount of ore added, including:

[0034] When the oxygen blowing ratio is 80%, the third stage addition amount of ore is M*10%-M*20%, and the converter auxiliary probe TSC temperature is controlled; where M represents the total weight of the ore;

[0035] The TSC temperature is ≤1580°C.

[0036] Optionally, the steelmaking raw materials are blown and the remaining limestone is added in a corresponding amount in the remaining stages to obtain molten steel, comprising:

[0037] The steelmaking raw materials are blown, and the remaining limestone is added in the remaining stage according to the corresponding addition amount, and the terminal carbon drawing temperature is controlled to obtain molten steel; wherein,

[0038] The final carbon drawing temperature is ≤1680°C.

[0039] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0040] The method for smelting steel with limestone provided in the embodiment of the present application makes full use of limestone slag making, and determines the calculation and correction method of the total amount of limestone added according to the Si content of molten iron; and designs an optimized limestone addition technical scheme, ultimately achieving the control of converter lime consumption below 10kg / ton of steel and a dephosphorization rate of more than 90%. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0042] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0043] Figure 1 A schematic flow chart of a method for smelting steel from limestone provided in an embodiment of the present application. DETAILED DESCRIPTION

[0044] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0045] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a hard limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numbers within the range. For example, the description of a range from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0046] In this application, unless otherwise specified, the directional words used, such as "upper" and "lower", refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of the present application specification, the terms "including", "comprising", etc. mean "including but not limited to". In this article, relational terms such as "first" and "remaining" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" means one or more, and "plurality" means two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple.

[0047] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0048] In the first aspect, the present application provides a method for smelting steel from limestone, see Figure 1 , the method comprising:

[0049] S1. Determine the total amount of limestone to be added based on the Si content in the chemical composition of the molten iron, and add the limestone in stages according to the corresponding addition amount; wherein,

[0050] Mixing the limestone added in the first stage amount with molten iron and scrap steel to obtain steelmaking raw materials;

[0051] S2. Blowing the steelmaking raw materials, and adding the remaining limestone in a corresponding amount in the remaining stage to obtain molten steel.

[0052] In the embodiment of the present application, in view of the situation that when a steel plant has a periodic shortage of lime supply, the traditional limestone is used to replace the lime steelmaking process, and efficient dephosphorization cannot be achieved, and the smelting of low-phosphorus steel varieties is severely restricted, a method for smelting steel with limestone is proposed. First, the total amount of limestone to be added is determined by the Si content in the molten iron. In the embodiment of the present application, the amount of lime added in the converter slag making raw material is controlled within 10kg / t. Therefore, the CaO provided by the lime is not enough to meet the dephosphorization alkalinity requirement, so limestone is needed to supplement CaO. When the amount of lime added is relatively a fixed value, the Si content in the molten iron determines the amount of limestone added. The higher the Si content, the more limestone is needed. The amount of limestone can be calculated based on the alkalinity balance, but the amount needs to be adjusted based on the slag volume. Secondly, limestone is added in stages, with the following positive effects: The limestone is added in three batches. The first, 50%, is added before charging the molten iron. This allows the furnace temperature and the physical heat of the molten iron to calcine the lime, thereby increasing the slag alkalinity in the early stages of blowing. The second and third additions are both made early in the blowing process. This continues to calcine the lime, replenishing the slag alkalinity and achieving rapid slagging, which promotes the early dephosphorization reaction. All limestone additions must be made early to suppress the early rise in the melt pool temperature and provide the thermodynamic conditions for dephosphorization. This method fully utilizes limestone slagging, keeping converter lime consumption below 10 kg / ton of steel and achieving a dephosphorization rate of over 90%.

[0053] In some embodiments, the Si content and the total amount of limestone added W satisfy the following relationship:

[0054] W=(23+50*w (Si) ).γ

[0055] Where w (Si) represents the Si content, γ represents the correction coefficient, and W represents the total amount of limestone added;

[0056] If the Si content in molten iron is ≤0.3 wt%, γ = 1;

[0057] If the Si content in molten iron is 0.3 wt% < ≤ 0.4 wt%, γ = 1.3;

[0058] If the Si content in molten iron is 0.4 wt% < ≤ 0.5 wt%, γ = 1.5;

[0059] If the Si content in molten iron is 0.5 wt% < ≤ 0.6 wt%, γ = 1.7;

[0060] If Si in molten iron is greater than 0.6 wt%, γ=2.

[0061] In the embodiment of the present application, first, when the Si content in the molten iron is ≤0.3 wt%, the amount of slag generated by Si oxidation and the heat released are limited. Regression statistics are performed on the heat data within this Si content range and the dephosphorization rate ≥90%, and the fitting formula W=(23+50*w (Si) ).γ

[0062] At this time, γ = 1, and serves as the basis for adjusting the Si content of molten iron;

[0063] Secondly, in converter steelmaking operations, a 0.1% fluctuation in molten iron Si content is usually used as the minimum unit for basicity and heat balance calculations. Therefore, the Si content range for molten iron is divided into 0.1% stages.

[0064] In addition, when the Si content of molten iron increases, if we only rely on the basic fitting formula W = (23 + 50 * w (Si)), we can calculate the amount of limestone to be added. However, the high Si content in molten iron will also cause an increase in oxidation heat release, and additional limestone needs to be added to balance the heat. Therefore, γ is the heat balance coefficient. The value of γ is determined based on the relationship between the heat released by the oxidation of 0.1 Si content and the cooling capacity of limestone. The γ value will be different for different tonnage converters and different limestone compositions, and can be calculated based on the heat balance reaction.

[0065] In some embodiments, the amount added in the first stage is W*50%.

[0066] In an embodiment of the present application, limestone is added to the converter after the scrap steel is loaded, and the amount of limestone added is W*50%; after the limestone is added, the furnace is first shaken backward to ≤-60°, and then the furnace is shaken forward to ≥90°, and then the molten iron is loaded to ensure that the limestone does not accumulate locally in the furnace; after the converter is loaded with iron, blowing begins, and the ignition gun position is controlled at 200-220cm. After the ignition is successful, the gun position is immediately controlled to 240cm.

[0067] The positive effect of controlling the initial limestone addition to W*50% is that it ensures sufficient lime is calcined. If the addition is too high, it may cause some difficulty in ignition during the blowing process; if the addition is too low, it may lead to low basicity in the early stages of blowing.

[0068] In some embodiments, the blowing of the steelmaking raw materials and the addition of the remaining limestone in a corresponding amount in the remaining stages to obtain molten steel comprises:

[0069] The steelmaking raw materials are blown, and the remaining limestone is added in a corresponding amount according to the oxygen blowing ratio in the remaining stage to obtain molten steel; wherein,

[0070] When the oxygen blowing ratio is 6%, the limestone having the second stage addition amount is added; wherein the second stage addition amount is W*30%.

[0071] The positive effect of controlling the second limestone addition to W*30% is that it continues to calcine limestone and replenishes slag basicity. If this addition is too high, the bath temperature may drop sharply, making slagging difficult. If this addition is too low, the basicity may be low in the early stages of blowing.

[0072] In some embodiments, the blowing of the steelmaking raw materials and the addition of the remaining limestone in a corresponding amount in the remaining stages to obtain molten steel comprises:

[0073] The steelmaking raw materials are blown, and the remaining limestone is added in a corresponding amount according to the oxygen blowing ratio in the remaining stage to obtain molten steel; wherein,

[0074] When the oxygen blowing ratio is 22%-25%, the limestone having the third stage addition amount is added; wherein the third stage addition amount is W*20%.

[0075] The positive effect of controlling the third limestone addition to W*20% is that it allows for continued limestone calcination and replenishes slag basicity. If this addition is too high, the bath temperature may drop sharply, making slagging difficult. If this addition is too low, the basicity may be low in the early stages of blowing.

[0076] In some embodiments, the content of the scrap steel is ≤10 wt%.

[0077] The positive effect of controlling the scrap steel content to ≤ 10 wt% is that the steelmaking process has sufficient heat to ensure the decomposition of limestone without affecting the final heat balance. Specifically, the scrap steel content can be 10 wt%, 9 wt%, 8 wt%, etc.

[0078] In some embodiments, the blowing of the steelmaking raw materials and the addition of the remaining limestone in a corresponding amount in the remaining stages to obtain molten steel comprises:

[0079] The steelmaking raw materials are blown, and the remaining limestone is added in corresponding amounts in the remaining stages according to the oxygen blowing ratio, and the addition amounts of lime, light-burned dolomite and ore are controlled in stages to obtain molten steel.

[0080] The positive effect of adding slag-making materials in batches according to the oxygen blowing ratio is that the slag-making process is carried out evenly, avoiding the concentrated addition of materials, which would cause a sudden drop in the molten pool temperature. The positive effect of controlling the addition amount of lime, light-burned dolomite and ore in stages is that the slag-making process is carried out evenly, avoiding the concentrated addition of materials, which would cause a sudden drop in the molten pool temperature.

[0081] In some embodiments, the steelmaking raw materials are blown, and the remaining limestone is added in corresponding amounts in the remaining stages according to the oxygen blowing ratio, and the addition amounts of lime, light-burned dolomite, and ore are controlled in stages to obtain molten steel, including:

[0082] The steelmaking raw materials are blown, and the remaining limestone is added in corresponding amounts in the remaining stages according to the oxygen blowing ratio, and the addition amounts of lime, light-burned dolomite and ore are controlled in stages to obtain molten steel; wherein,

[0083] When the oxygen blowing ratio is 6%, the limestone having the second-stage addition amount is added, the second-stage addition amount is W*30%, the first-stage addition amount of the lime is 4kg / t-4.5kg / t, the first-stage addition amount of the light-burned dolomite is 4kg / t-4.5kg / t, and the first-stage addition amount of the ore is M*55%-M*60%;

[0084] When the oxygen blowing ratio is 22%-25%, the limestone having the third-stage addition amount is added, the third-stage addition amount is W*20%, the second-stage addition amount of the lime is 4kg / t-4.5kg / t, the second-stage addition amount of the light-burned dolomite is 9kg / t-10kg / t, and the second-stage addition amount of the ore is M*20%-M*30%;

[0085] When the oxygen blowing ratio is 80%, the amount of ore added in the third stage is M*10%-M*20%; wherein M represents the total amount of ore added.

[0086] The positive effect of controlling the lime addition rate in the first stage to 4kg / t-4.5kg / t is that the lime directly participates in slag formation, and together with the lime produced by limestone calcination, forms slag. Specifically, the addition rate can be 4kg / t, 4.2kg / t, 4.3kg / t, 4.4kg / t, 4.5kg / t, etc.

[0087] The positive effect of controlling the initial addition of light-burned dolomite to 4kg / t-4.5kg / t is that adding a small amount of light-burned dolomite reduces the viscosity of the slag in the early stages, facilitating faster slagging. Specifically, the addition amount can be 4kg / t, 4.2kg / t, 4.3kg / t, 4.4kg / t, 4.5kg / t, etc.

[0088] The positive effect of controlling the first-stage ore addition to M*55%-M*60% is to improve the oxidizability of the slag in the early stage. Specifically, the addition amount can be M*55%, M*56%, M*57%, M*58%, M*59%, M*60%, etc.

[0089] The positive effect of controlling the lime addition amount in the second stage to 4kg / t-4.5kg / t is that it forms slag together with the lime produced by calcining limestone. Specifically, the amount can be 4kg / t, 4.2kg / t, 4.3kg / t, 4.4kg / t, 4.5kg / t, etc.

[0090] The positive effect of controlling the second-stage addition of light-burned dolomite to 9kg / t-10kg / t is that slag formation is completed and the MgO content is replenished. Specifically, the addition amount can be 9kg / t, 9.5kg / t, 10kg / t, etc.

[0091] The positive effect of controlling the second-stage ore addition to M*20%-M*30% is to ensure that the slag oxidizability does not decrease rapidly in the early stage. Specifically, the addition amount can be M*20%, M*22%, M*24%, M*26%, M*28%, M*30%, etc.

[0092] The positive effect of controlling the third-stage ore addition to M*10%-M*20% is to ensure that the slag maintains high oxidizability during the dynamic blowing process. Specifically, this addition can be M*10%, M*12%, M*14%, M*16%, M*18%, M*20%, etc.

[0093] In some embodiments, when the oxygen blowing ratio is 80%, the amount of ore added in the third stage is M*10%-M*20%; wherein M represents the total amount of ore added, including:

[0094] When the oxygen blowing ratio is 80%, the third stage addition amount of ore is M*10%-M*20%, and the converter auxiliary probe TSC temperature is controlled; where M represents the total weight of the ore;

[0095] The TSC temperature is ≤1580°C.

[0096] The positive effect of controlling the TSC temperature to ≤ 1580°C is to suppress the blowing process temperature and provide the thermodynamic basis for dephosphorization. Specifically, the temperature can be 1580°C, 1575°C, 1570°C, etc.

[0097] In some embodiments, the blowing of the steelmaking raw materials and the addition of the remaining limestone in a corresponding amount in the remaining stages to obtain molten steel comprises:

[0098] The steelmaking raw materials are blown, and the remaining limestone is added in the remaining stage according to the corresponding addition amount, and the terminal carbon drawing temperature is controlled to obtain molten steel; wherein,

[0099] The final carbon drawing temperature is ≤1680°C.

[0100] The positive effect of controlling the final carbon drawing temperature to ≤1680°C is to avoid high-temperature rephosphorization in the later stage of blowing. Specifically, the temperature can be 1680°C, 1675°C, 1670°C, etc.

[0101] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards. If there are no corresponding national standards, then the methods are carried out in accordance with general international standards, conventional conditions, or according to the conditions recommended by the manufacturer.

[0102] Example 1:

[0103] 1. For a 210-ton converter, the amount of scrap steel used is 15 tons, and the Si content of the molten iron is 0.29%. Therefore, the amount of limestone added to this furnace is determined to be 41.5 kg / t.

[0104] 2. After adding scrap steel to the converter, add 20.75kg / t of limestone into the furnace, shake the furnace backward to -60°, then shake the furnace forward to 90°, and wait for iron loading;

[0105] 3. After the converter is loaded with iron, start blowing. The ignition gun position is 220cm. After ignition is successful, immediately control the gun position to 240cm;

[0106] 4. After the start of blowing, the amount of limestone added to the first batch is 12.45kg / t, lime is added 4.31kg / t, and light-burned dolomite is added 4.33kg / t, and the total amount of ore added is 3.11kg / t;

[0107] 5. Add the second batch of materials at an oxygen blowing ratio of 22%, including 8.3 kg / t of limestone, 4.6 kg / t of lime, 9.52 kg / t of light-burned dolomite, and 1.52 kg / t of ore. No slag-making materials are added until the TSC measurement is completed.

[0108] 6. When the oxygen blowing ratio reaches 80%, use the auxiliary gun to measure TSC. The measured temperature is 1566℃. According to the calculation results of the auxiliary gun model, 2.1kg / t of ore is added.

[0109] 7. When carbon pulling is completed at the end of blowing, the terminal temperature is controlled to be 1675℃.

[0110] Example 2:

[0111] 1. For a 210-ton converter, the amount of scrap steel used is 14 tons, and the Si content of the molten iron is 0.48%. Therefore, the amount of limestone added to this furnace is determined to be 70.5 kg / t.

[0112] 2. After adding scrap steel to the converter, add 35.25kg / t of limestone into the furnace, shake the furnace backward to -60°, then shake the furnace forward to 90°, and wait for iron loading;

[0113] 3. After the converter is loaded with iron, start blowing. The ignition gun position is 220cm. After ignition is successful, immediately control the gun position to 240cm;

[0114] 4. After the first batch of blowing is started, the amount of limestone added is 21.15kg / t, lime is added is 4.23kg / t, light-burned dolomite is added is 4.41kg / t, and the amount of ore added is 6.23kg / t;

[0115] 5. Add the second batch of materials at an oxygen blowing ratio of 22%, including 14.1 kg / t of limestone, 4.3 kg / t of lime, 9.32 kg / t of light-burned dolomite, and 3.33 kg / t of ore. No slag-making materials are added until the TSC measurement is measured after the second batch of materials are added.

[0116] 6. When the oxygen blowing ratio reaches 80%, use the auxiliary gun to measure TSC. The measured temperature is 1576℃. According to the calculation results of the auxiliary gun model, 4.86kg / t of ore is added.

[0117] 7. When carbon pulling is completed at the end of blowing, the terminal temperature is controlled to be 1666℃.

[0118] Example 3:

[0119] 1. For a 210-ton converter, the amount of scrap steel used is 18 tons, and the Si content of the molten iron is 0.52%. Therefore, the amount of limestone added to this furnace is determined to be 83.3 kg / t.

[0120] 2. After adding scrap steel to the converter, add 61.65kg / t of limestone into the furnace, shake the furnace backward to -60°, then shake the furnace forward to 90°, and wait for iron loading;

[0121] 3. After the converter is loaded with iron, start blowing. The ignition gun position is 220cm. After ignition is successful, immediately control the gun position to 240cm;

[0122] 4. After the first batch of blowing is started, the amount of limestone added is 24.99kg / t, lime is added is 5.33kg / t, light-burned dolomite is added is 4.11kg / t, and the amount of ore added is 7.03kg / t;

[0123] 5. Add the second batch of materials at an oxygen blowing ratio of 22%, including 16.66 kg / t of limestone, 4.3 kg / t of lime, 9.45 kg / t of light-burned dolomite, and 3.98 kg / t of ore. No slag-making materials are added until the TSC measurement is completed.

[0124] 6. When the oxygen blowing ratio reaches 80%, use the auxiliary gun to measure TSC. The measured temperature is 1574℃. According to the calculation results of the auxiliary gun model, 5.01kg / t of ore is added.

[0125] 7. When carbon pulling is completed at the end of blowing, the terminal temperature is controlled to be 1669℃.

[0126] Comparative Example 1:

[0127] 1. 210-ton converter, 20 tons of scrap steel, 0.43% Si content in molten iron, slag formation according to conventional steelmaking process.

[0128] 3. After the converter is loaded with iron, start blowing and control the gun position to 240cm;

[0129] 4. After the first batch of blowing is started, the amount of limestone added is 34.78kg / t, lime is added is 4.01kg / t, light-burned dolomite is added is 4.22kg / t, and the amount of ore added is 3.23kg / t;

[0130] 5. Add the second batch of materials at an oxygen blowing ratio of 22%, including 21.7 kg / t of limestone, 4.23 kg / t of lime, 9.12 kg / t of light-burned dolomite, and 3.78 kg / t of ore. After the addition of the second batch of materials and before TSC measurement, add another 8.69 kg / t of limestone, and no more materials will be added;

[0131] 6. When the oxygen blowing ratio reaches 80%, use the auxiliary gun to perform TSC measurement. The measurement temperature is 1611°C. According to the calculation results of the auxiliary gun model, 6.86 kg / t of ore is added.

[0132] 7. When carbon pulling is completed at the end of blowing, the terminal temperature is controlled to be 1672℃.

[0133] Table 1 Results of smelting molten steel in Examples 1-3 and Comparative Examples.

[0134] Serial number P content of molten iron (wt%) P content of steel (wt%) Dephosphorization rate (%) Lime consumption (kg / t) Example 1 0.112 0.011 90.17 8.91 Example 2 0.102 0.008 92.15 8.53 Example 3 0.101 0.01 90.09 9.63 Comparative Example 1 0.100 0.016 84 8.24

[0135] Table 1 and Examples 1-3 above show that this method fully utilizes limestone slag production in steelmaking, achieving converter lime consumption below 10 kg / ton of steel and a dephosphorization rate exceeding 90%. In contrast, the comparative example achieved a lower dephosphorization rate and experienced difficulty in blowing. At an oxygen blowing ratio of 33%, extensive slag overflow and splashing occurred, resulting in poor blowing stability. This method successfully addresses the technical challenges of achieving efficient dephosphorization in existing steelmaking processes using limestone as a substitute for lime.

[0136] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for smelting steel from limestone, characterized in that: The method comprises: According to the Si content in the chemical composition of the molten iron, the total amount of limestone to be added is determined, and the limestone is added in stages according to the corresponding addition amount; wherein, Mixing the limestone added in the first stage amount with molten iron and scrap steel to obtain steelmaking raw materials; Blowing the steelmaking raw materials, and adding the remaining limestone in a corresponding amount in the remaining stages to obtain molten steel; The Si content and the total amount of limestone added W satisfy the following relationship: W=(23+50* w(Si)) *c In the formula, w(Si) represents the Si content, γ represents the correction coefficient, and W represents the total amount of limestone added; If the Si content in molten iron is ≤0.3 wt%, γ = 1; If the Si content in molten iron is 0.3 wt% < ≤ 0.4 wt%, γ = 1.3; If the Si content in molten iron is 0.4 wt% < ≤ 0.5 wt%, γ = 1.5; If the Si content in molten iron is 0.5 wt% < ≤ 0.6 wt%, γ = 1.7; If Si in molten iron is greater than 0.6 wt%, γ = 2; The amount added in the first stage is W*50%; the content of the scrap steel is ≤10% by weight; The steelmaking raw materials are blown, and the remaining limestone is added in a corresponding amount in the remaining stage to obtain molten steel, comprising: The steelmaking raw materials are blown, and the remaining limestone is added in a corresponding amount according to the oxygen blowing ratio in the remaining stage to obtain molten steel; wherein, When the oxygen blowing ratio is 6%, the limestone having the second stage addition amount is added; wherein the second stage addition amount is W*30%; When the oxygen blowing ratio is 22%-25%, the limestone having the third stage addition amount is added; wherein the third stage addition amount is W*20%; The converter lime consumption of the method is less than 10 kg / ton of steel, and the dephosphorization rate is more than 90%.

2. The method according to claim 1, characterized in that The steelmaking raw materials are blown, and the remaining limestone is added in a corresponding amount in the remaining stage to obtain molten steel, comprising: The steelmaking raw materials are blown, and the remaining limestone is added in corresponding amounts in the remaining stages according to the oxygen blowing ratio, and the addition amounts of lime, light-burned dolomite and ore are controlled in stages to obtain molten steel.

3. The method according to claim 2, characterized in that The steelmaking raw materials are blown, and the remaining limestone is added in corresponding amounts in the remaining stages according to the oxygen blowing ratio, and the addition amounts of lime, light-burned dolomite and ore are controlled in stages to obtain molten steel, including: The steelmaking raw materials are blown, and the remaining limestone is added in corresponding amounts in the remaining stages according to the oxygen blowing ratio, and the addition amounts of lime, light-burned dolomite and ore are controlled in stages to obtain molten steel; wherein, When the oxygen blowing ratio is 6%, the limestone having the second-stage addition amount is added, the second-stage addition amount is W*30%, the first-stage addition amount of the lime is 4kg / t-4.5kg / t, the first-stage addition amount of the light-burned dolomite is 4kg / t-4.5kg / t, and the first-stage addition amount of the ore is M*55%-M*60%; When the oxygen blowing ratio is 22%-25%, the limestone having the third-stage addition amount is added, the third-stage addition amount is W*20%, the second-stage addition amount of the lime is 4kg / t-4.5kg / t, the second-stage addition amount of the light-burned dolomite is 9kg / t-10kg / t, and the second-stage addition amount of the ore is M*20%-M*30%; When the oxygen blowing ratio is 80%, the amount of ore added in the third stage is M*10%-M*20%; wherein M represents the total amount of ore added.

4. The method according to claim 3, characterized in that When the oxygen blowing ratio is 80%, the amount of ore added in the third stage is M*10%-M*20%; wherein M represents the total amount of ore added, including: When the oxygen blowing ratio is 80%, the third stage addition amount of ore is M*10%-M*20%, and the converter auxiliary probe TSC temperature is controlled; where M represents the total weight of the ore; The TSC temperature is ≤1580°C.

5. The method according to claim 1, wherein The steelmaking raw materials are blown, and the remaining limestone is added in a corresponding amount in the remaining stage to obtain molten steel, comprising: The steelmaking raw materials are blown, and the remaining limestone is added in the remaining stage according to the corresponding addition amount, and the terminal carbon drawing temperature is controlled to obtain molten steel; wherein, The final carbon drawing temperature is ≤1680°C.

Images