A method of preventing misaddition of alloys in an lf furnace

Abstract

The application discloses a method for preventing LF furnace alloy addition error, and belongs to the technical field of steel metallurgy. The steps are as follows: S1: converter smelting initial molten steel; S2: adding alloy at an argon blowing station according to process requirements to perform component coarse adjustment; and S3: adding alloy multiple times at an LF to adjust the component of molten steel; wherein, the LF establishes an alloy error prevention model, and specifically comprises: 3-1: building a storage module; 3-2: building a calculation module; and 3-3: building a processing module. The application simultaneously calculates the chemical component of the current molten steel by using the integral method and the iteration method, further calculates the component of the molten steel after adding the alloy, compares the component with the upper limit of the steel standard, and prohibits the addition of the alloy if the component exceeds the upper limit. The purpose is to reduce the risk of component exceeding the standard caused by excessive alloy addition during LF smelting, and the application has strong innovation and practicability, and can effectively overcome the component exceeding the standard caused by excessive alloy addition due to the non-representativeness of the steel sample during the component adjustment of the steel in the LF furnace.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, and more specifically, to a method for preventing incorrect alloy addition in an LF furnace. Background Technology

[0002] The LF (Ladle Refining Furnace) is a core secondary refining equipment in steel plants. Its core function is to adjust the composition and temperature of molten steel. Composition adjustment is achieved by adding ferroalloys, which requires calculating the type and amount to be added based on the current composition of the molten steel, the target composition, the content of ferroalloy elements, and the element recovery rate. Steel composition adjustment typically needs to be completed in multiple stages. For example, in a "converter-argon blowing station-LF-continuous casting" process, the alloy is initially adjusted when the steel is tapped from the converter, and multiple additions are needed during LF smelting to achieve precise composition. It is crucial to strictly control the amount of alloy added in the LF to avoid exceeding the standard upper limit of the molten steel composition, which could lead to downgrading, scrapping, and economic losses.

[0003] The accuracy of alloy addition calculation depends on the accurate acquisition of the current composition of molten steel. However, in industrial production, steel samples are usually sent to the laboratory for analysis to obtain composition data, which has two major drawbacks: First, due to limitations such as production rhythm, the steel samples may lack representativeness, and adjustments based on this may easily lead to excessive composition. Second, if the operator adds the alloy in advance while waiting for the test results, and then adds it back later without including it in the calculation, it is very easy to cause excessive composition.

[0004] To reduce the risk of excessive alloy additions leading to excessive component levels, steel companies have tried to mitigate the risk by improving employee skills and developing alloy models, but existing methods have not fundamentally eliminated the risk.

[0005] Chinese patent (publication number: 118813906 A) discloses a "method and apparatus for determining the amount of alloy added in LF refining." The approach is as follows: Calculate the carbon equivalent based on initial target values ​​for C and Mn content. When the carbon equivalent is close to the maximum carbon equivalent of the steel grade, calculate a correction value for Mn content based on the maximum carbon equivalent of the steel grade and the calculated carbon equivalent value. Then, calculate an intermediate target value for Mn content in LF refining based on the initial target value and the correction value. If the difference between the intermediate target value and the lower limit value of Mn content is significant, the final target value for Mn content in LF refining is determined to be the intermediate target value. However, this patent does not mention any error-proofing measures for adding too much alloy.

[0006] Chinese patent (authorization announcement number: CN 119685559 B) published "A whole-process intelligent refining system applied to LF refining furnace". This system involves the field of iron and steel metallurgy. It mentions an alloy calculation module, which can establish an alloy calculation model based on the process parameters and furnace conditions of each furnace to achieve automatic control of the amount of alloy added. However, it does not mention any error prevention methods.

[0007] The scientific paper "Development and Application of 120t LF Intelligent Control System" (Steelmaking, Vol. 40, No. 4, August 2024) mentions the method of building an LF model. The alloy model built has achieved good results in field application, but it does not mention error prevention measures.

[0008] The aforementioned publicly available information all indicate that existing technologies, when mentioning LF adjustment of molten steel chemical composition, do not consider how to prevent errors. Summary of the Invention

[0009] 1. The technical problem that the invention aims to solve

[0010] To address the shortcomings and deficiencies of existing technologies, this invention provides a method for preventing incorrect alloy addition in an LF furnace. This invention simultaneously calculates the chemical composition of the molten steel using both an overall method and an iterative method, and further verifies the composition of the molten steel after the addition of the alloy to be added. This composition is then compared with the upper limit of the steel grade standard. If the upper limit is exceeded, the addition of the alloy is prohibited. The aim is to reduce the risk of excessive alloy addition leading to excessive composition during LF furnace smelting. This method is highly innovative and practical, effectively overcoming the risk of excessive alloy addition causing composition exceeding the standard during steel grade composition adjustment in the LF furnace due to reasons such as unrepresentative steel samples.

[0011] 2. Technical Solution

[0012] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0013] The present invention discloses a method for preventing incorrect alloy addition in an LF furnace, the process route of which is: converter - argon blowing station - LF furnace - continuous casting; the steps are as follows:

[0014] S1: Converter smelting of primary steel; steel samples are taken before tapping to analyze their chemical composition; alloys are added during the tapping process in the converter according to process requirements for rough composition adjustment;

[0015] S2: The argon blowing station adds alloys to roughly adjust the composition according to process requirements;

[0016] S3: LF involves multiple additions of alloys to adjust the composition of the molten steel;

[0017] Among them, LF establishes an alloy error-proofing model, specifically including:

[0018] 3-1: Build the storage module, including the following:

[0019] 3-1-1: Record the control targets and upper limit chemical composition of the steel grade being smelted;

[0020] 3-1-2: Record the standard chemical composition of all alloys;

[0021] 3-1-3: Before tapping, take a sample of molten steel B1 from inside the converter and analyze and record its chemical composition;

[0022] 3-1-4: Record the types and amounts of each alloy material added during the steelmaking process, as well as the yield of each element;

[0023] 3-1-5: Record the types and amounts of each alloy material added in the argon blowing station process, as well as the yield of each element;

[0024] 3-1-6: Before leaving the argon blowing station, take a sample of molten steel C1 from the ladle and analyze and record its chemical composition;

[0025] 3-1-7: Record the weight of molten steel weighed when it leaves the argon blowing station;

[0026] 3-1-8: Record the types and amounts of alloy materials added to molten steel during the LF process smelting, as well as the yield of each element;

[0027] 3-1-9: During LF smelting, steel samples F1, F2...Fn were taken, and their chemical composition was analyzed and recorded;

[0028] 3-2: Setting up the computing module:

[0029] 3-2-1: Determine the current steel composition through the calculation module:

[0030] During LF furnace metallurgy, the chemical composition of the molten steel was calculated using two methods:

[0031] The first calculation method: "Overall method" calculation:

[0032] Based on the composition of steel sample B1 taken before tapping from the converter, the current composition of molten steel is calculated according to the type and amount of alloys added.

[0033] The second calculation method: Iterative method:

[0034] Steel samples are taken during the steelmaking process. When a new steel sample composition is available, it is used as the baseline, and the current steel composition is calculated based on the type and amount of alloys added later. When C1 is received, the C1 composition is used as the current chemical composition. When F1 is received, the F1 composition is used as the current chemical composition. If alloys are added after F1 is received, the F1 composition is used as the baseline for calculation. When F2 is received, the F2 composition is used as the current chemical composition. If alloys are added after F2 is received, the F2 composition is used as the baseline for calculation. This process continues until the current steel composition is obtained.

[0035] 3-2-2: Determine the composition of molten steel after the LF alloy to be added is added using the calculation module:

[0036] When adding various alloys (LF alloys to be added) based on the work instructions, operator experience, or alloy model calculations, the calculations are performed before the alloy weighing begins.

[0037] The overall composition of molten steel after the addition of the LF alloy is equal to the increase in the value of a certain element caused by the addition of the LF alloy plus the current composition of molten steel calculated by the "overall method".

[0038] The composition of molten steel after the addition of the LF alloy (iteration) = the increase in the value of a certain element caused by the addition of the LF alloy + the current composition of molten steel calculated by the "iteration method";

[0039] 3-3: Setting up the processing module:

[0040] When the "LF alloy to be added to the molten steel and the overall composition of the molten steel is greater than the upper limit of the LF grade steel leaving the station", the LF alloy to be added is not allowed to be weighed.

[0041] When the "composition of molten steel after adding LF alloy to molten steel (iteration) > upper limit of LF steel grade", the LF alloy to be added is not allowed to be weighed.

[0042] Furthermore, in S1, the added alloys include, but are not limited to, one or more of the following: carbon raisers, ferrosilicon, ferromanganese, ferrochrome, and ferrovanadium. The types and amounts of various alloys added are determined according to the work instructions, operator experience, or alloy models.

[0043] Furthermore, in S2, the added alloys include, but are not limited to, one or more of the following: carbon raisers, ferrosilicon, ferromanganese, ferrochrome, and ferrovanadium. The types and amounts of various alloys are determined according to the work instructions, operator experience, or alloy models.

[0044] Furthermore, in S3, the alloy added each time includes, but is not limited to, one or more of the following: carbon raiser, ferrosilicon, ferromanganese, ferrochrome, and ferrovanadium. The types and amounts of various alloys added are determined according to the work instructions, operator experience, or alloy model.

[0045] Furthermore, in the aforementioned calculation module, during the converter tapping process, due to the carbon-oxygen reaction, the carbon content decreases during tapping. The decrease value is related to the timing and amount of deoxidized aluminum added during tapping, as well as the tapping time. The carbon element decrease value during tapping is generally considered to be 0.005~0.01%. Therefore, in the above calculation, the calculation of the carbon content of the molten steel after tapping not only needs to be based on the type and amount of alloy added to calculate the current steel composition, but also needs to subtract the decrease value of carbon element during tapping.

[0046] Furthermore, the formula for calculating the amount of alloy added is: Alloy added = molten steel quantity * (target composition - current composition) / (alloy yield * alloy element content). This is a common formula in the metallurgical industry. However, the yield of the same alloy varies when it is added in different processes. The yield is lower during the tapping process and higher when it is added at the argon blowing station and LF.

[0047] 3. Beneficial effects

[0048] Compared with the prior art, the technical solution provided by this invention has the following advantages:

[0049] This invention calculates the chemical composition of molten steel simultaneously using both an "overall method" and an "iterative method," and further verifies the composition of the molten steel after the addition of the alloy to be added. Then, it compares the composition with the upper limit of the steel grade standard. If the upper limit is exceeded, the addition of the alloy is prohibited. The purpose is to reduce the risk of excessive alloy addition leading to excessive composition during LF furnace smelting. It has strong innovation and practicality, and can effectively overcome the accident of excessive alloy addition during the composition adjustment of steel grades in the "converter-argon blowing station-LF furnace-continuous casting" process due to reasons such as the lack of representativeness of steel samples. Attached Figure Description

[0050] Figure 1 This is a process flow diagram of the present invention;

[0051] Figure 2 This is the system operation interface of the present invention. Figure 1 ;

[0052] Figure 3 This is the system operation interface of the present invention. Figure 2 . Detailed Implementation

[0053] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0054] Example 1

[0055] from Figure 1 As can be seen, this embodiment is used for smelting a certain steel grade, and its process route is "converter - argon blowing station - LF furnace - continuous casting". The LF furnace composition standard for the steel grade is as follows:

[0056]

[0057] S1: Converter smelting of primary steel;

[0058] Before tapping, a sample of molten steel (B1) was taken and its chemical composition was analyzed. The composition was: [C]: 0.04%, [Si]: 0%, [Mn]: 0.055%, [Cr]: 0.02%, [V]: 0.004%, [Ti]: 0.0040%.

[0059] During the tapping process, according to the work instructions, add 500 kg of alloy FeSi75B, 4000 kg of high-carbon ferromanganese, 450 kg of high-carbon ferrochrome, and 100 kg of carbon raiser.

[0060] S2: At the argon blowing station, 300 kg of FeSi75B alloy and 1200 kg of medium-carbon ferromanganese are added according to the composition of the molten steel entering the station. After the alloy is added and the mixture is stirred vigorously for a period of time, a steel sample is taken with the following composition: C1: [C]: 0.136%, [Si]: 0.075%, [Mn]: 0.961%, [Cr]: 0.075%, [V]: 0.003%, [Ti]: 0.005%. The sample is weighed before leaving the station, and the weight of the molten steel is 305 tons.

[0061] S3: LF can add alloys multiple times to adjust the steel composition depending on the specific situation. LF establishes an alloy error-proofing model, as follows:

[0062] 3-1: Build the storage module, including the following:

[0063] 3-1-1: Record the control targets and upper limit chemical composition of the steel grade being smelted;

[0064]

[0065] 3-1-2: Record the standard chemical composition of all alloys;

[0066]

[0067] 3-1-3: Record the chemical composition of molten steel sample B1 taken from the converter furnace:

[0068]

[0069] 3-1-4: Record the types and amounts of each alloying material added during the steelmaking process, as well as the yield of each element:

[0070]

[0071]

[0072] 3-1-5: Record the types and amounts of each alloy material added in the argon blowing station process, as well as the yield of each element;

[0073]

[0074]

[0075] 3-1-6: Record the chemical composition of molten steel sample C1 taken from the ladle before leaving the argon blowing station:

[0076]

[0077] 3-1-7: Record the weight of molten steel when it leaves the argon blowing station.

[0078] The molten steel weighed 305 tons when it left the argon blowing station.

[0079] 3-1-8: If alloy materials are added to LF, record the type and amount of alloy materials added, and record the yield of each element;

[0080]

[0081] 3-1-9: During LF smelting, steel samples F1, F2...Fn were taken, and their chemical composition was analyzed and recorded;

[0082] 3-2: Set up the computing module as follows:

[0083] 3-2-1: Determination of the current steel composition:

[0084] When molten steel enters the LF (Lead Inlet / Outlet), the chemical composition of the molten steel is calculated using both the "overall method" and the "iterative method":

[0085] The "overall method" calculation: Based on the composition of steel sample B1 taken before tapping from the converter, the current composition of the molten steel is calculated according to the types and amounts of alloys added. The results are shown in the table below:

[0086]

[0087] Iterative method calculation:

[0088] Since no alloys are added to the molten steel from the argon blowing station to the LF station, the C1 composition is used as the chemical composition for the LF station (iteration).

[0089]

[0090] Referring to the chemical composition calculated by the "overall method" and the "iterative method", it can be seen that the C: 0.11%, Si: 0.12%, and Mn: 1.01% calculated by the "iterative method" are significantly lower than the corresponding values ​​calculated by the "overall method". The reason is that the steel flow time during the tapping process is short, the amount of alloy added is too large, and the bottom blowing effect of the ladle is poor. As a result, some alloys are not melted when the steel sample is taken before leaving the argon blowing station, and the composition of the steel sample is not representative, resulting in an artificially low C1 element content.

[0091] 3-2-2: Determination of the composition of molten steel after the addition of the LF alloy to be added:

[0092] When molten steel enters the LF treatment, the LF operator calculates the amount of alloy to be added based on the C1 composition and the target composition of LF. It is planned to add 332 kg of ferrosilicon and 2100 kg of high-carbon ferromanganese to adjust the composition of the molten steel.

[0093] Adding 332 kg of ferrosilicon to LF increases Si by 0.065%; adding 2100 kg of high-carbon ferromanganese to LF increases Mn by 0.46%.

[0094] After adding 332 kg of ferrosilicon to the molten steel, the Si content (overall) is 0.065% + 0.16% = 0.225%.

[0095] After adding 332 kg of ferrosilicon to LF, the Si content in the molten steel (iterative) = 0.065% + 0.12% = 0.185%.

[0096] After adding 2100 kg of high-carbon ferromanganese to LF, the total Mn content in the molten steel is 0.46% + 1.24% = 1.70%.

[0097] After adding 2100 kg of high-carbon ferromanganese to LF, the Mn content in the molten steel (iterative) = 0.46% + 1.01% = 1.47%.

[0098] 3-3: Setting up the processing module:

[0099] Since "after adding 2100kg of high-carbon ferromanganese to LF, the overall Mn content in the molten steel is 0.46% + 1.24% = 1.70% > the upper limit of Mn is 1.60%", therefore, 332kg of alloy ferrosilicon to be added to LF and 2100kg of high-carbon ferromanganese must not be weighed.

[0100] The LF operator adds alloys to adjust the composition of the molten steel, and the amount of alloy is determined by referring to the composition of the steel sample. In this case, the composition of the steel sample taken before leaving the argon blowing station is not representative, resulting in an artificially low C1 element content in the steel sample. If this method is not used, in large-scale industrial production, this 2100 kg of high-carbon ferromanganese would be added to the molten steel, resulting in excessive Mn content.

[0101] Example 2

[0102] from Figure 1-3 As can be seen, this embodiment is used for smelting a certain steel grade, and its process route is "converter - argon blowing station - LF furnace - continuous casting". The LF furnace composition standard for the steel grade is as follows:

[0103]

[0104] S1: Converter smelting of primary steel.

[0105] Before tapping, a sample of molten steel (B1) was taken and its chemical composition was analyzed: [C]: 0.032%, [Si]: 0%, [Mn]: 0.06%, [Ti]: 0.004%. During the tapping process, 300 kg of alloy low-carbon ferromanganese was added according to the work instructions.

[0106] S2: No alloying was added at the argon blowing station. A steel sample was taken before leaving the station: C1: [C]: 0.027%, [Si]: 0.005%, [Mn]: 0.132%, [Ti]: 0.006%. The sample was weighed before leaving the station, yielding 310 tons of molten steel.

[0107] S3: LF can be adjusted by adding alloys multiple times to adjust the composition of molten steel, depending on the specific circumstances;

[0108] LF establishes an alloy error-proofing model, as follows:

[0109] 3-1: Build the storage module, including the following:

[0110] 3-1-1: Record the control targets and upper limit chemical composition of the steel grade being smelted;

[0111]

[0112] 3-1-2: Record the standard chemical composition of all alloys;

[0113]

[0114] 3-1-3: Record the chemical composition of molten steel sample B1 taken from the converter furnace:

[0115]

[0116] 3-1-4: Record the types and amounts of each alloying material added during the steelmaking process, as well as the yield of each element:

[0117]

[0118]

[0119] 3-1-5: Record the types and amounts of each alloy material added in the argon blowing station process, as well as the yield of each element;

[0120] Unalloyed

[0121] 3-1-6: Record the chemical composition of molten steel sample C1 taken from the ladle before leaving the argon blowing station:

[0122]

[0123] 3-1-7: Record the weight of molten steel when it leaves the argon blowing station.

[0124] The molten steel weighed 310 tons when it left the argon blowing station.

[0125] 3-1-8: If alloying materials are added to the LF, record the type and amount of alloying materials added, and record the yield of each element.

[0126]

[0127] 3-1-9: During the LF smelting process, steel samples F1, F2...Fn were taken and their chemical composition was analyzed and recorded.

[0128] (a) First batch of alloy added:

[0129] 3-2: Set up the computing module as follows:

[0130] 3-2-1: Determination of the composition of molten steel before the first batch of alloys is added:

[0131] The operators took a steel sample F1 immediately after the molten steel entered the station, intending to adjust the composition by adding alloys based on the chemical composition of F1. However, due to time constraints, the first batch of alloy adjustments was performed before the F1 analysis results were received. Before weighing the alloys, the chemical composition of the current molten steel was calculated using both the "overall method" and the "iterative method."

[0132] The "overall method" calculation: Based on the composition of steel sample B1 taken before tapping from the converter, the current composition of the molten steel is calculated according to the types and amounts of alloys added. The results are shown in the table below:

[0133]

[0134] Iterative method calculation: Since no alloying was added to the molten steel from the argon blowing station to the present, the C1 composition was used as the chemical composition of the LF entering the station (iterative). The results are shown in the table below:

[0135]

[0136] Referring to the chemical composition calculated by the "overall method" and the "iterative method", it can be seen that the C: 0.027%, Si: 0.005%, Mn: 0.132%, Ti: 0.0060% calculated by the "iterative method" are quite close to the results calculated by the "overall method".

[0137] 3-2-2: Determination of the composition of molten steel after the first batch of LF alloys is added:

[0138] When molten steel enters the LF treatment, the LF operator calculates the amount of alloy to be added based on the C1 composition and the target composition of LF. It is planned to add 244 kg of low-carbon ferromanganese and 70:130 kg of ferrotitanium to adjust the composition of the molten steel.

[0139] Adding 244 kg of low-carbon ferromanganese to LF increases Mn by 0.068%; adding 130 kg of ferrotitanium to LF increases Ti by 0.024%.

[0140] LF plus 244kg of low-carbon ferromanganese (Mn) (monolithic) = 0.068% + 0.141% = 0.209%

[0141] LF plus 244kg of low-carbon ferromanganese (Mn) (iteration) = 0.068% + 0.132% = 0.200%

[0142] After adding 130kg of ferrotitanium to 70% of LF, the total Ti content in the molten steel is 0.024% + 0.004% = 0.028%.

[0143] After adding 130 kg of ferrotitanium to 70 molten steel, the Ti content (iterative) is 0.024% + 0.006% = 0.030%.

[0144] First batch of alloy processing modules to be added:

[0145] because:

[0146] LF plus 244kg of low-carbon ferromanganese (Mn) (total) = 0.068% + 0.141% = 0.209% < Mn upper limit of 0.30%

[0147] LF plus 244kg of low-carbon ferromanganese (Mn) (iteration) = 0.068% + 0.132% = 0.200% < Mn upper limit of 0.30%

[0148] After adding 130kg of ferrotitanium to 70% of the molten steel, the total Ti content (overall) is 0.024% + 0.004% = 0.028% < the upper limit of Ti (0.05%).

[0149] After adding 130 kg of ferrotitanium to 70% of LF, the Ti content in the molten steel (iterative) is 0.024% + 0.006% = 0.030% < Ti upper limit of 0.05%.

[0150] Therefore, the following alloys to be added: 244 kg of low-carbon ferromanganese and 70:130 kg of ferrotitanium can be weighed. Thus, 244 kg of low-carbon ferromanganese and 70:130 kg of ferrotitanium are weighed and added to the molten steel.

[0151] (ii) The second batch of alloy added:

[0152] 3-2: Set up the computing module as follows:

[0153] After receiving the chemical composition of steel sample F1 (see table below), the operator plans to add a second batch of alloy (191 kg of low-carbon ferromanganese and 70 kg of ferrotitanium) to further adjust the composition of the molten steel.

[0154]

[0155] 3-2-1: Determination of the composition of molten steel before the addition of the second batch of alloys (191 kg of low-carbon ferromanganese and 119 kg of ferrotitanium).

[0156] The chemical composition of the current molten steel is calculated using both the "overall method" and the "iterative method".

[0157] The results of the "holistic method" calculation are shown in the table below:

[0158]

[0159] The results of the iterative method calculation are shown in the table below:

[0160]

[0161] 3-2-2: Determination of the composition of molten steel after the addition of alloys in the second batch of LF:

[0162] Second batch of alloys to be added (191 kg of low-carbon ferromanganese, 119 kg of ferrotitanium 70):

[0163] Adding 191 kg of low-carbon ferromanganese to LF increases Mn by 0.053%; adding 119 kg of ferrotitanium to LF increases Ti by 0.022%.

[0164] LF plus 191kg of low-carbon ferromanganese (Mn) (monolithic) = 0.053% + 0.209% = 0.262%

[0165] LF plus 191kg of low-carbon ferromanganese (Mn) (iteration) = 0.053% + 0.147% = 0.200%

[0166] After adding 119 kg of ferrotitanium to 70 molten steel, the total Ti content (overall) is 0.022% + 0.028% = 0.050%.

[0167] After adding 119 kg of ferrotitanium to 70 molten steel, the Ti content (iterative) is 0.022% + 0.008% = 0.030%.

[0168] Second batch of modules awaiting alloy processing:

[0169] Since "LF plus 191kg low-carbon ferromanganese Mn (overall) = 0.053% + 0.209% = 0.262% > Mn upper limit 0.25%", and "LF plus 119kg ferrotitanium 70 after molten steel Ti (overall) = 0.022% + 0.028% = 0.050% > Ti upper limit 0.045%", therefore, 191kg low-carbon ferromanganese and 119kg ferrotitanium 70 are not allowed to be weighed.

[0170] In this embodiment, the operator adds the alloy while waiting for the F1 steel sample composition to be obtained. After obtaining the F1 steel sample composition, the operator calculates the alloy based on the F1 steel sample composition and prepares to add it, but forgets that the alloy was added before the F1 composition is reached. Without this error-proofing technology, the alloy would be added to the molten steel in the second batch, causing the Mn and Ti content of the molten steel to exceed the standard.

[0171] When smelting alloy steel in an LF furnace, phosphorus recovery and desulfurization are characterized. The changes in phosphorus and sulfur content in molten steel depend not only on the addition of alloys, but also on the amount of slag added to the converter and the slag-forming effect of the LF furnace. Therefore, this technology is not suitable for preventing errors in the addition of ferrophosphorus and ferrosulfur.

[0172] Aluminum is both a deoxidizing and alloying element. During the steelmaking process, the aluminum yield is affected by the final composition of the converter and the oxygen content, resulting in an unstable yield. During LF furnace smelting, the aluminum yield is also affected by multiple factors such as the amount of slag carried over from the converter and the amount of slag carried over from the ladle, making the yield unstable as well. Therefore, it is difficult to accurately calculate the Al content in molten steel. Consequently, this technology is not suitable for preventing errors in aluminum granules, aluminum-iron alloys, and other aluminum-containing alloys.

[0173] This invention calculates the chemical composition of molten steel simultaneously using both an "overall method" and an "iterative method," and further verifies the composition of the molten steel after the addition of the alloy to be added. Then, it compares the composition with the upper limit of the steel grade standard. If the upper limit is exceeded, the addition of the alloy is prohibited. The purpose is to reduce the risk of excessive alloy addition leading to excessive composition during LF furnace smelting. It has strong innovation and practicality, and can effectively overcome the accident of excessive alloy addition during the composition adjustment of steel grades in the "converter-argon blowing station-LF furnace-continuous casting" process due to reasons such as the lack of representativeness of steel samples.

[0174] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A method for preventing incorrect alloy addition in an LF furnace, characterized in that: Its process route is: converter - argon blowing station - LF furnace - continuous casting; The steps are as follows: S1: Converter smelting of primary steel; steel samples are taken before tapping to analyze their chemical composition; alloys are added during the tapping process in the converter according to process requirements for rough composition adjustment; S2: The argon blowing station adds alloys to roughly adjust the composition according to process requirements; S3: LF involves multiple additions of alloys to adjust the composition of the molten steel; Among them, LF establishes an alloy error-proofing model, specifically including: 3-1: Build the storage module, including the following: 3-1-1: Record the control targets and upper limit chemical composition of the steel grade being smelted; 3-1-2: Record the standard chemical composition of all alloys; 3-1-3: Before tapping, take a sample of molten steel B1 from inside the converter and analyze and record its chemical composition; 3-1-4: Record the types and amounts of each alloy material added during the steelmaking process, as well as the yield of each element; 3-1-5: Record the types and amounts of each alloy material added in the argon blowing station process, as well as the yield of each element; 3-1-6: Before leaving the argon blowing station, take a sample of molten steel C1 from the ladle and analyze and record its chemical composition; 3-1-7: Record the weight of molten steel weighed when it leaves the argon blowing station; 3-1-8: Record the types and amounts of alloy materials added to molten steel during the LF process smelting, as well as the yield of each element; 3-1-9: During LF smelting, steel samples F1, F2...Fn were taken, and their chemical composition was analyzed and recorded; 3-2: Setting up the computing module: 3-2-1: Determine the current steel composition through the calculation module: During LF furnace metallurgy, the chemical composition of the molten steel was calculated using two methods: The first calculation method: "whole-body method" calculation: Based on the composition of steel sample B1 taken before tapping from the converter, the current composition of molten steel is calculated according to the type and amount of alloys added. The second calculation method: "Iterative method" calculation: Steel samples are taken during the steelmaking process. When a new steel sample composition is available, it is used as the baseline, and the current steel composition is calculated based on the type and amount of alloys added later. When C1 is received, the C1 composition is used as the current chemical composition. When F1 is received, the F1 composition is used as the current chemical composition. If alloys are added after F1 is received, the F1 composition is used as the baseline for calculation. When F2 is received, the F2 composition is used as the current chemical composition. If alloys are added after F2 is received, the F2 composition is used as the baseline for calculation. This process continues until the current steel composition is obtained. 3-2-2: Determine the composition of molten steel after the LF alloy to be added is added using the calculation module: When adding various alloys (LF alloys to be added) based on the work instructions, operator experience, or alloy model calculations, the calculations are performed before the alloy weighing begins. The overall composition of molten steel after the addition of the LF alloy is equal to the increase in the value of a certain element caused by the addition of the LF alloy plus the current composition of molten steel calculated by the "overall method". The composition of molten steel after the addition of the LF alloy (iteration) = the increase in the value of a certain element caused by the addition of the LF alloy + the current composition of molten steel calculated by the "iteration method"; 3-3: Setting up the processing module: When "the overall composition of the molten steel after the LF alloy to be added is greater than the upper limit of the LF grade steel leaving the station", the LF alloy to be added is not allowed to be weighed; When the "composition of molten steel after adding LF alloy to molten steel (iteration) > upper limit of LF steel grade", the LF alloy to be added is not allowed to be weighed.

2. The method for preventing incorrect alloy addition in an LF furnace according to claim 1, characterized in that: In S1, the added alloys include, but are not limited to, one or more of the following: carbon raisers, ferrosilicon, ferromanganese, ferrochrome, and ferrovanadium. The types and amounts of various alloys added are determined according to the work instructions, operator experience, or alloy models.

3. The method for preventing incorrect alloy addition in an LF furnace according to claim 1, characterized in that: In S2, the added alloys include, but are not limited to, one or more of the following: carbon raisers, ferrosilicon, ferromanganese, ferrochrome, and ferrovanadium. The types and amounts of various alloys are determined according to the work instructions, operator experience, or alloy models.

4. The method for preventing incorrect alloy addition in an LF furnace according to claim 1, characterized in that: In S3, the alloy added each time includes, but is not limited to, one or more of the following: carbon raiser, ferrosilicon, ferromanganese, ferrochrome, and ferrovanadium. The types and amounts of various alloys added are determined according to the work instructions, operator experience, or alloy model.

5. The method for preventing incorrect alloy addition in an LF furnace according to claim 1, characterized in that: In the aforementioned calculation module, during the converter tapping process, due to the carbon-oxygen reaction, the carbon content decreases during tapping. The decrease value is related to the timing and amount of deoxidized aluminum added during tapping, the tapping time, etc. The carbon element decrease value during tapping is generally considered to be 0.005~0.01%. Therefore, in the above calculation, the calculation of the carbon content of the molten steel after tapping not only requires calculating the current composition of the molten steel based on the type and amount of alloy added, but also requires subtracting the decrease value of carbon elements after tapping.

6. The method for preventing incorrect alloy addition in an LF furnace according to claim 1, characterized in that: The formula for calculating the amount of alloy added is: Alloy added = Steel volume * (Target composition - Current composition) / (Alloy yield * Alloy element content). This is a common formula in the metallurgical industry. However, the yield of the same alloy varies when it is added in different processes. The yield is lower during the tapping process and higher when it is added at the argon blowing station and LF.

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