Method for accurately controlling alloy dosage in molten steel refining process

Abstract

The invention relates to a method for accurately controlling the alloy dosage in the molten steel refining process. The method comprises the steps that current initial chemical components and end point chemical components of molten steel of a current refining furnace are obtained; according to the sulfur content in the current end point chemical components, the sulfur content grade of the current refining furnace molten steel is determined; obtaining historical average initial chemical components and end-point chemical components of the same molten steel of the historical refining furnace with the same sulfur content grade and historical addition data of various alloys; obtaining first refining increment data corresponding to each alloy element according to the alloy element contents of the historical average initial chemical component and the average end point chemical component and historical addition data; and according to the first refining incremental data and the alloy element content of the historical initial chemical components and the end point chemical components, the target adding amount corresponding to various alloys of the molten steel of the current refining furnace is obtained. By means of the method, precise alloy adding in molten steel refining is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of molten steel smelting, and in particular to a method for accurately controlling the amount of alloy added during a molten steel refining process. Background Art

[0002] The steel industry is a major consumer of ferroalloys, and the consumption of steelmaking alloys accounts for more than 90% of the total ferroalloy consumption. Precise control of alloy composition during the smelting process can reduce ferroalloy consumption, reduce waste, and lower carbon emissions.

[0003] Therefore, it is extremely important to accurately control the alloying of the smelting process, reduce alloy consumption, lower the cost of smelting alloys, and improve product competitiveness. Summary of the invention

[0004] The present application provides a method for accurately controlling the amount of alloy added during molten steel refining to solve the following technical problem: how to achieve accurate addition of alloys during molten steel refining.

[0005] In a first aspect, the present application provides a method for accurately controlling the amount of alloy added during a molten steel refining process, the method comprising:

[0006] Obtaining the current initial chemical composition and the current endpoint chemical composition of the molten steel of the current refining heat;

[0007] Determining the sulfur content level of the molten steel in the current refining heat according to the sulfur content in the current endpoint chemical composition;

[0008] Obtain the historical average initial chemical composition, historical average final chemical composition of the same type of molten steel from historical refining heats with the same sulfur content level, as well as historical addition data with various alloys;

[0009] According to the alloying element contents of the historical average initial chemical composition and the historical average final chemical composition, respectively, and the historical addition data, the first refining increment data corresponding to each alloying element of the same type of molten steel of the same sulfur content grade in the historical refining heats is obtained;

[0010] According to the first refining increment data, and the alloy element contents of the historical initial chemical composition and the historical endpoint chemical composition, the target addition amounts corresponding to various alloys of the molten steel in the current refining heat are obtained.

[0011] Optionally, the sulfur content grades include: by mass fraction, Grade I: sulfur content ≤ 0.0010%; Grade II:

[0012] 0.0010%<sulfur content≤0.0020%; Grade III: 0.0020%<sulfur content≤0.0040%; Grade IV: 0.0040%<sulfur content≤0.0060%; Grade V: 0.0060%<sulfur content≤0.010%; Grade VI: 0.010%<sulfur content≤0.015%; Grade VII: sulfur content>0.015%.

[0013] Optionally, the historical addition data for each type of alloy include: the historical average addition amount of the alloy, the content of each alloying element in the alloy, and the yield rate of the main alloying element of the alloy.

[0014] Optionally, the first refining increment data corresponding to each alloying element of the same type of molten steel of the same sulfur content grade in the historical refining heats is obtained according to the respective alloying element contents of the historical average initial chemical composition and the historical average endpoint chemical composition, as well as the historical addition data, including:

[0015] According to the historical average addition amount of the alloy, the content of each alloy element of the alloy and the recovery rate of the main alloy element of the alloy, the second refining increment data corresponding to each alloy element is obtained;

[0016] According to the alloy element contents of the historical average initial chemical composition and the historical average final chemical composition, respectively, and the second refining increment data, the first refining increment data corresponding to each alloy element of the same type of molten steel in historical refining furnaces with the same sulfur content grade is obtained.

[0017] Optionally, the second refining increment satisfies the following relationship:

[0018] n2=(a×b×η÷t)+∑(c×d÷t)

[0019] In the formula, n2 represents the second refining increment, a represents the content of the main alloying elements of the alloy, b represents the historical average addition amount of the current alloy, η represents the recovery rate of the main alloying elements of the current alloy, t represents the molten steel content, c represents the content of the main alloying elements of the current alloy contained in the remaining categories of alloys, and d represents the corresponding historical average addition amount of the remaining categories of alloys.

[0020] Optionally, the first refined incremental data satisfies the following relationship:

[0021] n1=i 21 -i 20 -n2

[0022] In the formula, i 21 represents the content of alloying elements in the historical average endpoint chemical composition, i 20represents the content of alloying elements in the historical average initial chemical composition, n1 represents the first refining increment, and n2 represents the second refining increment.

[0023] Optionally, the target addition amount corresponding to each alloy of the molten steel in the current refining heat satisfies the following relationship:

[0024] m=(i 11 -i 10 -n1-n3) / a / η

[0025] Where Δi represents the refining increment of alloying elements in the historical refining heats, i 11 Indicates the content of alloying elements in the current endpoint chemical composition, i 10 It represents the content of alloying elements in the current initial chemical composition, a represents the content of main alloying elements in the current alloy, η represents the yield of main alloying elements in the current alloy, n3 represents the sum of the contents of main alloying elements contained in the current alloy by other categories of alloys, and m represents the target addition amount of each alloy in the current refining heat of molten steel.

[0026] Optionally, the alloy includes: medium carbon ferromanganese, ferrosilicon, low carbon ferrochrome, ferrophosphorus, carbon wire, double-layer pure calcium wire, and a carburizer.

[0027] Optionally, the alloy elements include: C, Si, Mn, Cr, P, and Ca.

[0028] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0029] The method for accurately controlling the amount of alloy added in the molten steel refining process provided in the embodiment of the present application, wherein the molten steel refining includes a desulfurization operation, and different sulfur contents require different amounts of slag added in the refining process, different refining bottom blowing intensities, and different refining times, which result in different increments of alloy elements in the refining process, and thus the sulfur content grade of the molten steel in the current refining furnace is determined according to the endpoint sulfur content of the molten steel refining; the molten steel is smelted in a primary refining furnace, and in the subsequent refining process, due to the presence of auxiliary materials such as electrodes, slag, and refractory materials, the content of alloy elements in the steel will increase during the refining process, and therefore the alloy increment brought by the refining process is considered during the alloy addition process, thereby reducing the amount of alloy added and accurately controlling the composition of alloy elements in the steel; according to the molten steel grade standard and the molten steel of the current refining furnace, the average initial chemical composition, average endpoint chemical composition, and historical addition data of various ferroalloys in the refining of the smelting history of the molten steel of the same grade are collected, and different alloy refining increments can be obtained respectively, so that the alloys involved in the corresponding alloy elements in the initial and endpoint chemical compositions of the molten steel of the current refining furnace are accurately added. This method can achieve precise control of alloy elements, reduce the amount of alloy elements added, reduce smelting costs, and meet the needs of industrial and mass smelting. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] 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.

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0032] Figure 1 The present invention is a flow chart of a method for accurately controlling the amount of alloy added in a molten steel refining process according to some embodiments of the present application. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0034] 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 rigid 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 numerical values ​​within the range. For example, the range description 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 apply 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.

[0035] In this application, the terms "including", "comprising", etc. mean "including but not limited to".

[0036] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0037] Figure 1 This is a flow chart of a method for accurately controlling the amount of alloy added during a molten steel refining process according to some embodiments of the present application; see Figure 1 The present application provides a method for accurately controlling the amount of alloy added during a molten steel refining process, the method comprising:

[0038] S1. Obtain the current initial chemical composition and the current endpoint chemical composition of the molten steel of the current refining heat;

[0039] S2. Determine the sulfur content level of the molten steel in the current refining heat according to the sulfur content in the current endpoint chemical composition;

[0040] In some embodiments, the sulfur content grades include: by mass fraction, Grade I: sulfur content ≤ 0.0010%; Grade II: 0.0010%<sulfur content ≤ 0.0020%; Grade III: 0.0020%%<sulfur content ≤ 0.0040%; Grade IV: 0.0040%<sulfur content ≤ 0.0060%; Grade V: 0.0060%<sulfur content ≤ 0.010%; Grade VI: 0.010%<sulfur content ≤ 0.015%; Grade VII: sulfur content > 0.015%.

[0041] In the embodiment of the present application, desulfurization operation is performed during molten steel refining. Different sulfur contents require different slag addition amounts, refining bottom blowing intensities and refining times during the refining process, resulting in different increments of alloy elements during the refining process. The alloy increments during the refining process are graded according to different sulfur content requirements and are divided into the above-mentioned 7 grade standards: Grade I, Grade II, Grade III, Grade IV, Grade V, Grade VI and Grade VII.

[0042] S3. Obtain the historical average initial chemical composition, historical average final chemical composition of the same type of molten steel from historical refining heats with the same sulfur content level, and historical addition data with various alloys;

[0043] In some embodiments, the historical addition data for each type of alloy includes: the historical average addition amount of the alloy, the content of each alloying element in the alloy, and the yield of the main alloying element of the alloy.

[0044] S4, obtaining first refining increment data corresponding to each alloying element of the same type of molten steel of the same sulfur content grade in historical refining heats according to the alloying element contents of the historical average initial chemical composition and the historical average final chemical composition, as well as the historical addition data;

[0045] In some embodiments, the first refining increment data corresponding to each alloying element of the same type of molten steel of the same sulfur content grade in the historical refining heats is obtained according to the respective alloying element contents of the historical average initial chemical composition and the historical average endpoint chemical composition, and the historical addition data, including:

[0046] According to the historical average addition amount of the alloy, the content of each alloy element of the alloy and the recovery rate of the main alloy element of the alloy, the second refining increment data corresponding to each alloy element is obtained;

[0047] According to the alloy element contents of the historical average initial chemical composition and the historical average final chemical composition, respectively, and the second refining increment data, the first refining increment data corresponding to each alloy element of the same type of molten steel in historical refining furnaces with the same sulfur content grade is obtained.

[0048] In some embodiments, the second refined increment satisfies the following relationship:

[0049] n2=(a×b×η÷t)+∑(c×d÷t)

[0050] In the formula, n2 represents the second refining increment, a represents the content of the main alloying elements of the alloy, b represents the historical average addition amount of the current alloy, η represents the recovery rate of the main alloying elements of the current alloy, t represents the molten steel content, c represents the content of the main alloying elements of the current alloy contained in the remaining categories of alloys, and d represents the corresponding historical average addition amount of the remaining categories of alloys.

[0051] In some implementations, the first refined incremental data satisfies the following relationship:

[0052] n1=i 21 -i 20 -n2

[0053] In the formula, i 21 represents the content of alloying elements in the historical average endpoint chemical composition, i 20 represents the content of alloying elements in the historical average initial chemical composition, n1 represents the first refining increment, and n2 represents the second refining increment.

[0054] In some embodiments, the alloy includes: medium carbon ferromanganese, ferrosilicon, low carbon ferrochrome, ferrophosphorus, carbon wire, double-layer pure calcium wire, and a carburizer.

[0055] In some embodiments, the alloying elements include: C, Si, Mn, Cr, P, Ca.

[0056] In the embodiments of the present application, the smelting history is analyzed according to the classification levels of different sulfur contents, and the refining increments of alloys with different sulfur content levels under the same process conditions are calculated, including the refining carbon increase Δ[C], the refining silicon increase Δ[Si], the refining manganese increase Δ[Mn], the refining chromium increase Δ[Cr], the refining phosphorus increase Δ[P] and the refining calcium increase Δ[Ca], etc.

[0057] In the embodiment of the present application, for example, n1=i21 -i 20 -n2 can be converted into the calculation method of refining carbon increase Δ[C]: carbon content at the end of refining (end point) - carbon content at the refining station (initial) - carbon content of various alloys brought into the steel liquid, the specific calculation is:

[0058]

[0059] The refining silicon increase Δ[Si] is the increment of silicon content in the molten steel caused by the refining process; the refining silicon increase Δ[Si] is characterized in that the refining silicon increase Δ[Si] is calculated as follows: silicon content at the end of refining - silicon content at the refining station - silicon content brought into the molten steel by various alloys, and the specific calculation is:

[0060]

[0061] The refining manganese increase Δ[Mn] is the increment of manganese content in the molten steel caused by the refining process; the refining manganese increase Δ[Mn] is characterized in that the calculation method of the refining manganese increase Δ[Mn] is: the manganese content at the end of refining - the manganese content entering the refining station - the manganese content brought into the molten steel by various alloys, and the specific calculation is:

[0062]

[0063] The refining chromium increase Δ[Cr] is the increment of chromium content in the molten steel caused by the refining process; the refining chromium increase Δ[Cr] is characterized in that the calculation method of the refining chromium increase Δ[Cr] is: the chromium content at the end of refining - the chromium content at the refining station - the chromium content of various alloys brought into the molten steel, and the specific calculation is:

[0064]

[0065] The refining calcium increase Δ[Ca] is the increment of calcium content in the molten steel caused by the refining process; the refining calcium increase is characterized in that the refining calcium increase Δ[Ca] is calculated as follows: calcium content at the end of refining - calcium content at the refining station - calcium content of various alloys brought into the molten steel - calcium content brought into the calcium line, specifically calculated as:

[0066]

[0067] The refining phosphorus increase Δ[P] is the increment of phosphorus content in the molten steel during the refining process. The refining phosphorus increase is characterized by that the refining phosphorus increase Δ[P] is calculated as follows: phosphorus content at the end of refining - phosphorus content at the refining station - phosphorus content brought into the refining of various alloys. The specific calculation is:

[0068]

[0069] S5. According to the first refining increment data and the alloy element contents of the historical initial chemical composition and the historical endpoint chemical composition, the target addition amounts corresponding to various alloys of the molten steel in the current refining heat are obtained.

[0070] In some embodiments, the target addition amount of each alloy corresponding to the molten steel in the current refining heat satisfies the following relationship:

[0071] m=(i 11 -i 10 -n1-n3) / a / η

[0072] Where Δi represents the refining increment of alloying elements in the historical refining heats, i 11 Indicates the content of alloying elements in the current endpoint chemical composition, i 10 It represents the content of alloying elements in the current initial chemical composition, a represents the content of main alloying elements in the current alloy, η represents the yield of main alloying elements in the current alloy, n3 represents the sum of the contents of main alloying elements contained in the current alloy by other categories of alloys, and m represents the target addition amount of each alloy in the current refining heat of molten steel.

[0073] In the embodiment of the present application, the molten steel is smelted in a primary furnace. In the subsequent refining process, due to the presence of auxiliary materials such as electrodes, slag and refractory materials, the content of alloy elements in the steel will increase during the refining process. Therefore, the alloy increment brought by the refining process is considered during the alloy addition process, thereby reducing the amount of alloy addition and accurately controlling the composition of the alloy elements in the steel; according to the molten steel grade standard and the molten steel of the current refining furnace, the average initial chemical composition, average terminal chemical composition and historical addition data of various ferroalloys in the refining of the same grade of molten steel are collected, and different alloy refining increments can be obtained respectively, so as to accurately add the alloys involved according to the corresponding alloy elements in the initial and terminal chemical compositions of the molten steel of the current refining furnace. Exemplarily, m=(i 11 -i 10 -n1-n3) / a / η can be converted to:

[0074] The amount of alloy containing element i kg / t = ([% i] 精炼结束 -[%i] 精炼进站 -[%Δi] 精炼增量 )×10 / alloy i content% / η 合金i收得率％

[0075] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0076] Example 1

[0077] A method for accurately controlling the amount of alloy added during molten steel refining, comprising:

[0078] (1) Molten steel smelting and process

[0079] The molten steel is Q690D, and the molten steel smelting process is: primary furnace smelting - refining - continuous casting.

[0080] The molten steel needs to be desulfurized during the refining process, and the refining and desulfurization process will cause the carbon, silicon, manganese and calcium content of the molten steel to increase. Therefore, when accurately controlling the composition of the molten steel during the refining process, the impact of the refining increment must be considered.

[0081] (2) Smelting and refining composition requirements

[0082] The main component requirements of the molten steel refining process are shown in Table 1. The main components are carbon, silicon, manganese and calcium, and the processes are refining entry and refining end.

[0083] Table 1 Initial chemical composition and final chemical composition of molten steel refining wt%

[0084]

[0085] The alloy elements required in the refining process are: carbon, silicon, manganese and calcium.

[0086] (3) Analysis of smelting and refining increments

[0087] The molten steel composition control requires that the sulfur content [S] = 0.0008% at the end of refining. Deep desulfurization treatment is required for refining. According to this requirement, the refining increment of historical smelting furnaces of molten steel of Grade I (sulfur content ≤ 0.0010%) is analyzed.

[0088] For the same grade of molten steel, the smelting composition data of historical furnace refining entering and ending the batch production are shown in Table 2 below.

[0089] Table 2 Historical average initial chemical composition and historical average final chemical composition (wt%) of historical refining

[0090]

[0091] The data of alloy addition amount in the refining process of historical furnaces of molten steel with the same requirement grade are shown in Table 3 below.

[0092] Table 3 Alloy addition amount in historical furnace refining process

[0093] Alloy Type Carbon raiser / t High carbon ferromanganese / t Medium carbon ferromanganese / t Ferrosilicon / t Double layer pure calcium wire / m average value 0.045 0.064 0.09 0.07 150

[0094] The alloy information used in the historical refining process of steel with the same required grade, including the alloy element content and the yield of the main alloy, is shown in Table 4 below.

[0095] Table 4 Alloy information used in the refining process of historical heats of steel with the same requirement grade

[0096]

[0097] The amount of molten steel in the historical furnaces with the same process is 223t. According to the increment calculation formula in the refining process, the refining increment of the molten steel in the historical furnaces is calculated separately, including the refining carbon increase Δ[C], refining silicon increase Δ[Si], refining manganese increase Δ[Mn], and refining calcium increase Δ[Ca]. The specific calculation is as follows.

[0098] 1) Calculation of carbon addition during refining process:

[0099]

[0100] 2) Calculation of silicon increase during refining process:

[0101]

[0102] 3) Calculation of manganese increase during refining process:

[0103]

[0104] 4) Calculation of calcium increase during refining process:

[0105]

[0106] (4) Precise calculation of refined alloy

[0107] In this furnace smelting, according to the requirements of molten steel composition, the increase of alloy element content in molten steel during the refining process is taken into consideration, and the alloy addition during the refining process is carried out. The precise calculation of various alloy additions is as follows.

[0108] The amount of alloy containing element i kg / t = ([% i] 精炼结束 -[%i] 精炼进站 -[%Δi] 精炼增量 )×10 / alloy i content% / η 合金i收得率％

[0109] The addition calculations for each different alloy are as follows.

[0110] 1) Accurate calculation of manganese-containing alloys

[0111] When adding Mn to manganese-containing alloys, if all high-carbon ferromanganese is used, the carbon increase brought by the high-carbon ferromanganese, plus the carbon increase during the refining process, will cause the carbon content of the finished product to exceed the standard. Therefore, medium-carbon ferromanganese is used to add Mn.

[0112] The amount of Mn added to medium carbon ferromanganese is calculated as follows:

[0113] Medium carbon ferromanganese dosage kg / t = ([%Mn] 精炼结束 -[%Mn] 精炼进站 -[%ΔMn] 精炼增量 )×10 / alloy Mn content% / η 合金收得率％ =(1.45-1.10-0.027) / 80.18% / 95.16%=4.42kg / t

[0114] When medium carbon ferromanganese is added with Mn, the carbon content will increase. The calculation of carbon increase brought by medium carbon ferromanganese is:

[0115] % Medium carbon ferromanganese carbon addition = alloy addition amount × % alloy C content / 1000 = 4.42 × 1.66 / 1000 = 0.0073

[0116] 2) Accurate calculation of silicon-containing alloys

[0117] When adding Si to silicon-containing alloys, the amount of Si added is calculated accurately, and the increment during the refining process is taken into consideration. Ferrosilicon is used to add Si.

[0118] The amount of ferrosilicon added to Si is calculated as follows:

[0119] Ferrosilicon dosage kg / t = ([%Si] 精炼结束 -[%Si] 精炼进站 -[%ΔSi] 精炼增量 )×10 / alloy Si content% / η 合金i收得率％

[0120] =(0.20-0.14-0.0249) / 73.88% / 97.68%=0.49kg / t

[0121] When ferrosilicon is added with Si, the carbon content will increase. The calculation of the carbon increase brought by ferrosilicon is:

[0122] % Silicon iron carbon increase = alloy addition amount × % alloy C content / 1000 = 0.49 × 0.121 / 1000 = 0.0001

[0123] 3) Accurate calculation of carbon-containing alloys

[0124] When carbon is added to carbon-containing alloys, the amount of carbon added must be accurately calculated. While considering the increment during the refining process, the amount of carbon added by the alloy must also be considered, and a carburizer should be used to add C.

[0125] The amount of carburizer C is calculated as follows:

[0126] Carbon enhancer dosage kg / t = ([% C] 精炼结束 -[%C] 精炼进站 -[%ΔC] 精炼增量 -∑[%ΔC] 合金增量 )×10 /

[0127] Alloy C content% / η 合金i收得率％

[0128] =(0.12-0.08-0.0127-0.0073-0.0001) / 92.36% / 40.25%=0.54kg / t

[0129] 4) Accurate calculation of calcium-containing alloys

[0130] When adding Ca to calcium-containing alloys, the amount of Ca added must be accurately calculated, and the increment during the refining process must be considered. Double-layer pure calcium wire is used to add Ca.

[0131] The amount of Ca added to the double-layer pure calcium wire is calculated as:

[0132] Double-layer pure calcium wire dosage km=([%Ca] 精炼结束 -[%Ca] 精炼进站 -[%ΔCa] 精炼增量 ) / calcium thread powder dosage×1000 /

[0133] Alloy Ca content% / η 合金i收得率％

[0134] =(0.0012-0.0002-0.00029) / 50×1000 / 95% / 20.25%=0.074km

[0135] Therefore, the refining process comprehensively considers the requirements for changes in the composition of the molten steel, the increment of the refining process, as well as the alloy composition, yield and other factors, and obtains the precisely controlled amount of alloy added in the refining process.

[0136] (5) Alloy addition calculation without considering refining increment

[0137] In order to compare the changes in alloy addition without considering the refining increment, the alloy addition amounts of each alloy without considering the refining process increment were calculated, and the calculation process is as follows.

[0138] The amount of alloy containing element i kg / t = ([% i] 精炼结束 -[%i] 精炼进站)×10 / alloy i content% / η 合金i收得率％

[0139] The addition calculations for each different alloy are as follows.

[0140] 1) Accurate calculation of manganese-containing alloys

[0141] When adding Mn to manganese-containing alloys, if all high-carbon ferromanganese is used, the carbon increase brought by high-carbon ferromanganese will cause the carbon content of the finished product to exceed the standard. Therefore, medium-carbon ferromanganese is used for manganese addition.

[0142] Calculation of Mn addition amount for medium carbon ferromanganese:

[0143] Medium carbon ferromanganese dosage kg / t = ([%Mn] 精炼结束 -[%Mn] 精炼进站 )×10 / alloy Mn content% / η 合金收得率％

[0144] =(1.45-1.10) / 80.18% / 95.16%=4.59kg / t

[0145] When medium carbon ferromanganese is added with Mn, the carbon content will increase. The calculation of carbon increase brought by medium carbon ferromanganese is:

[0146] % Medium carbon ferromanganese carbon addition = alloy addition amount × % alloy C content / 1000 = 4.59 × 1.66 / 1000 = 0.0076

[0147] 2) Accurate calculation of silicon-containing alloys

[0148] When adding Si to silicon-containing alloys, the amount of addition is calculated accurately, and ferrosilicon is used to match Si.

[0149] The amount of ferrosilicon added to Si is calculated as follows:

[0150] Ferrosilicon dosage kg / t = ([%Si] 精炼结束 -[%Si] 精炼进站 )×10 / alloy Si content% / η 合金i收得率％

[0151] =(0.20-0.14) / 73.88% / 97.68%=0.83kg / t

[0152] When ferrosilicon is added with Si, the carbon content will increase. The calculation of the carbon increase brought by ferrosilicon is:

[0153] % Ferrosilicon carbon addition = alloy addition amount × % alloy C content / 1000 = 0.83 × 0.121 / 1000 = 0.0001

[0154] 3) Accurate calculation of carbon-containing alloys

[0155] When carbon-containing alloys are mixed with C, the amount of addition must be accurately calculated, and the amount of carbon added by the alloy must be considered. A carburizer should be used to mix C.

[0156] The amount of carburizer C is calculated as follows:

[0157] Carbon enhancer dosage kg / t = ([% C] 精炼结束 -[%C] 精炼进站 -∑[%ΔC] 合金增量 )×10 /

[0158] Alloy C content% / η 合金i收得率％

[0159] =(0.12-0.08-0.0073-0.0001) / 92.36% / 40.25%=0.87kg / t

[0160] 4) Accurate calculation of calcium-containing alloys

[0161] When adding Ca to calcium-containing alloys, the amount of Ca added is accurately calculated, and a double-layer pure calcium wire is used to add Ca.

[0162] The amount of Ca added to the double-layer pure calcium wire is calculated as:

[0163] Double-layer pure calcium wire dosage km=([%Ca] 精炼结束 -[%Ca] 精炼进站 ) / calcium thread powder dosage×1000 /

[0164] Alloy Ca content% / η 合金i收得率％

[0165] =(0.0012-0.0002) / 50×1000 / 95% / 20.25%=0.104km

[0166] In summary, under the condition of considering the refining increment, the precise control of the molten steel composition can be achieved; at the same time, compared with not considering the refining increment, the precise control of the alloy addition amount is achieved, the amount of alloy used is reduced, and the smelting cost is reduced. The comparison of the alloy addition amount in the refining process under the two conditions is shown in Table 5 below.

[0167] Table 5 Alloy addition amount during refining process

[0168]

[0169] Example 2

[0170] A method for accurately controlling the amount of alloy added during molten steel refining, comprising:

[0171] (1) Molten steel smelting and process

[0172] The molten steel is SQ550NH, and the molten steel smelting process is: primary furnace smelting - refining - continuous casting.

[0173] The molten steel needs to be desulfurized during the refining process, and the refining and desulfurization process will cause the molten steel to increase in carbon, silicon, manganese, chromium, phosphorus and calcium. Therefore, when accurately controlling the composition of the molten steel during the refining process, the impact of the refining increment must be considered.

[0174] (2) Smelting and refining composition requirements

[0175] The main component requirements of the molten steel refining process are shown in Table 6 below. The main components are carbon, silicon, manganese, chromium, phosphorus and calcium. The processes are refining entry and refining end.

[0176] Table 6 Initial chemical composition and final chemical composition of molten steel refining wt%

[0177]

[0178] The alloy elements required in the refining process are: carbon, silicon, manganese, chromium, phosphorus and calcium.

[0179] (3) Analysis of smelting and refining increments

[0180] The molten steel composition control requires that the sulfur content [S] = 0.0015% at the end of refining. Deep desulfurization treatment is required for refining. In view of this requirement, the refining increments of historical smelting furnaces of molten steel with sulfur content level II: 0.0010% < sulfur content ≤ 0.0020% are analyzed.

[0181] For the same grade of molten steel, the smelting composition data of historical furnace refining entering and ending the batch production are shown in Table 7 below.

[0182] Table 7 Historical average initial chemical composition and historical average final chemical composition wt% of historical heat refining

[0183]

[0184] The data of alloy addition amount in the refining process of historical furnaces of molten steel with the same required grade are shown in Table 8 below.

[0185] Table 8 Alloy additions in historical furnace refining process

[0186] Alloy Type Medium carbon ferromanganese / t Ferrosilicon / t Low carbon ferrochrome / t Ferrophosphorus / t Carbon line / km Double layer pure calcium wire / km average value 0.351 0.114 0.137 0.0972 0.089 0.15

[0187] The alloy information used in the historical refining process of steel with the same requirement grade, including the alloy element content and the yield of the main alloy, is shown in Table 9 below.

[0188] Table 9 Alloy information used in the refining process of historical heats of molten steel with the same requirement grade

[0189]

[0190] The amount of molten steel in the historical furnaces of the same process is 225t. According to the incremental calculation formula in the refining process, the refining increment of the molten steel in the historical furnaces is calculated separately, including the refining carbon increase Δ[C], refining silicon increase Δ[Si], refining manganese increase Δ[Mn], refining phosphorus increase Δ[Cr], refining phosphorus increase Δ[P], and refining calcium increase Δ[Ca]. The specific calculation is as follows:

[0191] 1) Calculation of carbon addition during refining process:

[0192]

[0193] 2) Calculation of silicon increase during refining process:

[0194]

[0195] 3) Calculation of manganese increase during refining process:

[0196]

[0197] 4) Calculation of chromium addition during refining process:

[0198]

[0199] 5) Calculation of phosphorus addition during refining process:

[0200]

[0201] 6) Calculation of calcium increase during refining process:

[0202]

[0203] (4) Precise calculation of refined alloy

[0204] In this furnace smelting, according to the requirements of molten steel composition, the increase of alloy element content in molten steel during the refining process is taken into consideration, and the alloy addition during the refining process is carried out. The precise calculation of various alloy additions is as follows.

[0205] The amount of alloy containing element i kg / t = ([% i] 精炼结束 -[%i] 精炼进站 -[%Δi] 精炼增量 )×10 / alloy i content% / η 合金i收得率％

[0206] The calculation of the addition of different alloys in the smelting process is as follows.

[0207] 1) Accurate calculation of manganese-containing alloys

[0208] When adding Mn to manganese-containing alloys, the increment in the refining process must be considered, and medium carbon ferromanganese should be used for adding Mn.

[0209] The amount of Mn added to medium carbon ferromanganese is calculated as follows:

[0210] Medium carbon ferromanganese dosage kg / t = ([%Mn] 精炼结束 -[%Mn] 精炼进站 -[%ΔMn] 精炼增量 )×10 / alloy Mn content% / η 合金收得率％ =(1.00-0.80-0.0118) / 80.18% / 95.16%=2.42kg / t

[0211] When medium carbon ferromanganese is added with Mn, the carbon content and phosphorus content will increase. The calculation of the carbon increase and phosphorus increase brought by medium carbon ferromanganese are as follows:

[0212] % Medium carbon ferromanganese carbon addition = alloy addition amount × % alloy C content / 1000 = 2.42 × 1.66 / 1000 = 0.0040

[0213] % Medium carbon ferromanganese phosphorus addition = alloy addition amount × % alloy P content / 1000 = 2.42 × 0.129 / 1000 = 0.0003

[0214] 2) Accurate calculation of silicon-containing alloys

[0215] When adding Si to silicon-containing alloys, the amount of Si added is calculated accurately, and the increment during the refining process is taken into consideration. Ferrosilicon is used to add Si.

[0216] The amount of ferrosilicon added to Si is calculated as follows:

[0217] Ferrosilicon dosage kg / t = ([%Si] 精炼结束 -[%Si] 精炼进站 -[%ΔSi] 精炼增量 )×10 / alloy Si content% / η 合金i收得率％

[0218] =(0.350-0.250-0.0213)×10 / 73.88% / 97.68%=1.09kg / t

[0219] When ferrosilicon is matched with Si, the carbon content and phosphorus content will increase. The carbon and phosphorus content increased by ferrosilicon are calculated as follows:

[0220] % Silicon iron carbon increase = alloy addition amount × % alloy C content / 1000 = 1.09 × 0.121 / 1000 = 0.0001

[0221] % Phosphorus addition to ferrosilicon = alloy addition amount × % P content in alloy / 1000 = 1.09 × 0.163 / 1000 = 0.0002

[0222] 3) Accurate calculation of chromium-containing alloys

[0223] When adding Cr to chromium-containing alloys, the amount of Cr added must be accurately calculated, the increment in the refining process must be considered, and low-carbon ferrochrome should be used to add Cr.

[0224] The amount of Cr added to low carbon ferrochrome is calculated as:

[0225] Low carbon ferrochrome addition amount kg / t = ([%Cr] 精炼结束 -[%Cr] 精炼进站 -[%ΔCr] 精炼增量 )×10 / alloy Cr content% / η 合金i收得率％

[0226] =(0.450-0.400-0.0049)×10 / 52.0% / 95.0%=0.91kg / t

[0227] When low carbon ferrochrome is added with Cr, the carbon content and phosphorus content will increase. The carbon and phosphorus content increased by low carbon ferrochrome are calculated as follows:

[0228] %Carbon addition of low carbon ferrochrome = alloy addition amount × %C content of alloy / 1000 = 0.91 × 0.10 / 1000 = 0.0001

[0229] %Low carbon ferrochrome phosphorus addition = alloy addition amount × % alloy P content / 1000 = 0.91 × 0.001 / 1000 = 0.0000

[0230] 4) Accurate calculation of phosphorus-containing alloys

[0231] When adding P to phosphorus-containing alloys, the amount of addition should be calculated accurately. While considering the increment in the refining process, the amount of phosphorus added by the alloy must also be considered, and phosphorus iron should be used to add P.

[0232] The amount of ferrophosphorus added is calculated as follows:

[0233] Phosphorus iron addition amount kg / t = ([%P] 精炼结束 -[%P] 精炼进站 -[%ΔP] 精炼增量 -∑[%ΔP] 合金增量 )×10 / alloy P content% / η 合金i收得率％ =(0.063-0.050-0.0016-0.0003-0.0002) / 26.87% / 90.0%=0.45kg / t

[0234] When ferrophosphorus is added with P, the carbon content will increase. The carbon increase brought by ferrophosphorus is calculated as:

[0235] %Phosphorus iron carbon increase = alloy addition amount × % alloy C content / 1000 = 0.45 × 0.04 / 1000 = 0.0000

[0236] 5) Accurate calculation of carbon-containing alloys

[0237] When carbon-containing alloys are mixed with C, the amount of addition is calculated accurately. While considering the increment in the refining process, the amount of carbon added by the alloy must also be considered, and carbon wire is used to mix C.

[0238] The amount of carbon wire C is calculated as follows:

[0239] Carbon wire addition amount km = ([% C] 精炼结束 -[%Ci] 精炼进站 -[%ΔC] 精炼增量 -∑[%ΔC] 合金增量 ) / Carbon powder dosage×1000 /

[0240] Carbon wire C content% / η 合金i收得率％

[0241] =(0.045-0.022-0.0118-0.0040-0.0001-0.0001) / 138×1000 / 99.0% / 80.0%=0.065km

[0242] 6) Accurate calculation of calcium-containing alloys

[0243] When adding Ca to calcium-containing alloys, the amount of Ca added must be accurately calculated, the increment during the refining process must be considered, and a double-layer pure calcium wire should be used to add Ca.

[0244] The amount of Ca added to the double-layer pure calcium wire is calculated as:

[0245] Double-layer pure calcium wire dosage km=([%Ca] 精炼结束 -[%Ca] 精炼进站 -[%ΔCa] 精炼增量 ) / calcium powder dosage×1000

[0246] / Alloy Ca content % / η 合金i收得率％

[0247] =(0.0015-0.0002-0.0003) / 50×1000 / 95% / 20.25%=0.108km

[0248] Therefore, the refining process comprehensively considers the requirements for changes in the composition of the molten steel, the increment of the refining process, as well as the alloy composition, yield and other factors, and obtains the precisely controlled amount of alloy added in the refining process.

[0249] (5) Alloy addition calculation without considering refining increment

[0250] In order to compare the changes in alloy addition without considering the refining increment, the alloy addition amounts of each alloy without considering the refining process increment were calculated, and the calculation process is as follows.

[0251] The amount of alloy containing element i kg / t = ([% i] 精炼结束 -[%i] 精炼进站 )×10 / alloy i content% / η 合金i收得率％

[0252] Without considering the refining increment, the addition calculations for different alloys are as follows:

[0253] 1) Accurate calculation of manganese-containing alloys

[0254] When adding Mn to manganese-containing alloys, medium carbon ferromanganese is used for manganese addition.

[0255] The amount of Mn added to medium carbon ferromanganese is calculated as follows:

[0256] Medium carbon ferromanganese dosage kg / t = ([%Mn] 精炼结束 -[%Mn] 精炼进站 )×10 / alloy Mn content% / η 合金收得率％

[0257] =(1.00-0.80) / 80.18% / 95.16%=2.62kg / t

[0258] When medium carbon ferromanganese is added with Mn, the carbon content and phosphorus content will increase. The calculation of the carbon increase and phosphorus increase brought by medium carbon ferromanganese are as follows:

[0259] % Medium carbon ferromanganese carbon addition = alloy addition amount × % alloy C content / 1000 = 2.62 × 1.66 / 1000 = 0.0044

[0260] % Medium carbon ferromanganese phosphorus addition = alloy addition amount × % alloy P content / 1000 = 2.62 × 0.129 / 1000 = 0.0003

[0261] 2) Accurate calculation of silicon-containing alloys

[0262] When adding Si to silicon-containing alloys, the amount of Si added is accurately calculated, and ferrosilicon is used for adding Si.

[0263] The amount of ferrosilicon added to Si is calculated as follows:

[0264] Ferrosilicon dosage kg / t = ([%Si] 精炼结束 -[%Si] 精炼进站 )×10 / alloy Si content% / η 合金i收得率％

[0265] =(0.350-0.250)×10 / 73.88% / 97.68%=1.39kg / t

[0266] When ferrosilicon is added with Si, the carbon content and phosphorus content will increase. The carbon increase and phosphorus increase brought by ferrosilicon are calculated as follows: % ferrosilicon carbon increase = alloy addition amount × % alloy C content / 1000 = 1.39 × 0.121 / 1000 = 0.0002

[0267] % Phosphorus addition to ferrosilicon = alloy addition amount × % P content in alloy / 1000 = 1.39 × 0.163 / 1000 = 0.0002

[0268] 3) Accurate calculation of chromium-containing alloys

[0269] When adding Cr to chromium-containing alloys, the amount of Cr added is accurately calculated, and low-carbon ferrochrome is used to add Cr.

[0270] The amount of Cr added to low carbon ferrochrome is calculated as:

[0271] Low carbon ferrochrome addition amount kg / t = ([%Cr] 精炼结束 -[%Cr] 精炼进站 )×10 / alloy Cr content% / η 合金i收得率％

[0272] =(0.450-0.400)×10 / 52.0% / 95.0%=1.01kg / t

[0273] When low carbon ferrochrome is added with Cr, the carbon content and phosphorus content will increase. The carbon and phosphorus content increased by low carbon ferrochrome are calculated as follows:

[0274] %Carbon addition of low carbon ferrochrome = alloy addition amount × %C content of alloy / 1000 = 1.01 × 0.10 / 1000 = 0.0001

[0275] %Low carbon ferrochrome phosphorus addition = alloy addition amount × % alloy P content / 1000 = 0.91 × 0.001 / 1000 = 0.0000

[0276] 4) Accurate calculation of phosphorus-containing alloys

[0277] The accurate calculation of the amount of phosphorus added when adding phosphorus to phosphorus-containing alloys requires consideration of the phosphorus addition brought into the alloy and the use of phosphorus-iron addition.

[0278] The amount of ferrophosphorus added is calculated as follows:

[0279] Phosphorus iron addition amount kg / t = ([%P] 精炼结束 -[%P] 精炼进站 -∑[%ΔP] 合金增量 )×10 / alloy P content% / η 合金i收得率％

[0280] =(0.063-0.050-0.0003-0.0002) / 26.87% / 90.0%=0.51kg / t

[0281] When ferrophosphorus is added with P, the carbon content will increase. The carbon increase brought by ferrophosphorus is calculated as:

[0282] %Phosphorus iron carbon increase = alloy addition amount × % alloy C content / 1000 = 0.51 × 0.04 / 1000 = 0.0000

[0283] 5) Accurate calculation of carbon-containing alloys

[0284] When carbon-containing alloys are mixed with C, the amount of addition must be accurately calculated, and the amount of carbon added by the alloy must be considered. Carbon wire is used to mix C.

[0285] The amount of carbon wire C is calculated as follows:

[0286] Carbon wire addition amount km = ([% C] 精炼结束 -[%ΔC] 精炼增量 -∑[%ΔC] 合金增量 ) / Carbon powder dosage×1000 /

[0287] Carbon wire C content% / η 合金i收得率％

[0288] =(0.045-0.022-0.0044-0.0002-0.0001) / 138×1000 / 99.0% / 80.0%=0.172km

[0289] 6) Accurate calculation of calcium-containing alloys

[0290] When adding Ca to calcium-containing alloys, the amount of Ca added is accurately calculated, and a double-layer pure calcium wire is used to add Ca.

[0291] The amount of Ca added to the double-layer pure calcium wire is calculated as:

[0292] Double-layer pure calcium wire dosage km=([%Ca] 精炼结束 -[%Ca] 精炼进站 ) / calcium wire powder dosage×1000 / alloy Ca content% / η 合金i收得率％ =(0.0015-0.0002) / 50×1000 / 95% / 20.25%=0.135km

[0293] In summary, under the condition of considering the refining increment, the precise control of the molten steel composition can be achieved. At the same time, compared with not considering the refining increment, the precise control of the alloy addition amount is achieved, the amount of alloy used is reduced, and the smelting cost is reduced. The comparison of the alloy addition amount in the refining process under the two conditions is shown in Table 10 below.

[0294] Table 10 Alloy addition amount during refining process

[0295]

[0296] In summary, a method for accurately controlling the amount of alloy added in the molten steel refining process provided in the embodiment of the present application takes into account the increments of different alloy elements in the refining process under different refining intensities, thereby achieving accurate control of alloy elements in the smelting process and meeting the requirements for controlling the molten steel smelting composition. At the same time, the amount of alloy added can be reduced, thereby reducing the cost of smelting alloys and meeting the needs of industrialization and batch smelting.

[0297] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for accurately controlling the amount of alloy added during molten steel refining. It is characterized in that The method comprises: Obtaining the current initial chemical composition and the current endpoint chemical composition of the molten steel of the current refining heat; Determining the sulfur content level of the molten steel in the current refining heat according to the sulfur content in the current endpoint chemical composition; Obtain the historical average initial chemical composition, historical average final chemical composition of the same type of molten steel from historical refining heats with the same sulfur content level, as well as historical addition data with various alloys; According to the alloying element contents of the historical average initial chemical composition and the historical average final chemical composition, and the historical addition data, the first refining increment data corresponding to each alloying element of the same type of molten steel in the historical refining heats with the same sulfur content grade is obtained; According to the first refining increment data, and the alloy element contents of the historical initial chemical composition and the historical endpoint chemical composition, the target addition amounts corresponding to various alloys of the molten steel in the current refining heat are obtained.

2. The method according to claim 1, It is characterized in that The sulfur content grades include: calculated by mass fraction, Grade I: sulfur content ≤ 0.0010%; Grade II: 0.0010%<sulfur content ≤ 0.0020%; Grade III: 0.0020%<sulfur content ≤ 0.0040%; Grade IV: 0.0040%<sulfur content ≤ 0.0060%; Grade V: 0.0060%<sulfur content ≤ 0.010%; Grade VI: 0.010%<sulfur content ≤ 0.015%; Grade VII: sulfur content > 0.015%.

3. The method according to claim 1, It is characterized in that The historical addition data of various alloys include: the historical average addition amount of the alloy, the content of each alloying element in the alloy and the recovery rate of the main alloying element of the alloy.

4. The method according to claim 3, It is characterized in that The first refining increment data corresponding to each alloying element of the same type of molten steel of the same sulfur content grade in the historical refining heats is obtained according to the respective alloying element contents of the historical average initial chemical composition and the historical average endpoint chemical composition, as well as the historical addition data, including: According to the historical average addition amount of the alloy, the content of each alloy element of the alloy and the recovery rate of the main alloy element of the alloy, the second refining increment data corresponding to each alloy element is obtained; According to the alloy element contents of the historical average initial chemical composition and the historical average final chemical composition, respectively, and the second refining increment data, the first refining increment data corresponding to each alloy element of the same type of molten steel in historical refining furnaces with the same sulfur content grade is obtained.

5. The method according to claim 4, It is characterized in that The second refining increment satisfies the following relationship n 2 =(a×b×η÷t)+∑(c×d÷t) Where n 2 represents the second refining increment, a represents the content of the main alloying elements of the current alloy, b represents the historical average addition amount of the alloy, η represents the recovery rate of the main alloying elements of the current alloy, t represents the molten steel content, c represents the content of the main alloying elements of the current alloy contained in the remaining categories of alloys, and d represents the corresponding historical average addition amount of the remaining categories of alloys.

6. The method according to claim 5, It is characterized in that The first refined incremental data satisfies the following relationship: n 1 =i 21 -i 20 -n 2 In the formula, i 21 represents the content of alloying elements in the historical average endpoint chemical composition, i 20 represents the content of alloying elements in the historical average initial chemical composition, n 1 represents the first refining increment, n 2 Indicates the second refinement increment.

7. The method according to claim 6, It is characterized in that The target addition amount corresponding to each alloy of the current refining heat of molten steel satisfies the following relationship: m=(i 11 -i 10 -n 1 -n 3 ) / a / η Where Δi represents the refining increment of alloying elements in the historical refining heats, i 11 Indicates the content of alloying elements in the current endpoint chemical composition, i 10 represents the content of alloying elements in the current initial chemical composition, a represents the content of the main alloying elements in the current alloy, η represents the yield of the main alloying elements in the current alloy, and n 3 It represents the sum of the contents of the main alloying elements of the current alloy contained in the remaining categories of alloys, and m represents the target addition amount corresponding to each alloy in the current refining heat of molten steel.

8. The method according to claim 1, It is characterized in that The alloy comprises: medium carbon ferromanganese, ferrosilicon, low carbon ferrochrome, ferrophosphorus, carbon wire, double-layer pure calcium wire and carburizer.

9. The method according to claim 1, It is characterized in that The alloy elements include: C, Si, Mn, Cr, P, and Ca.

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