A method for predicting the composition content of mixed cast steel liquid

Abstract

The present invention belongs to the technical field of steelmaking, and in particular relates to a method for predicting the content of components in mixed-cast steel liquid. The content w0 of a specific component in the tundish steel liquid before continuous casting is obtained; the tundish steel liquid is used for continuous casting to obtain the real-time weight p of the tundish steel liquid and the amount of molten steel q in the ladle for casting during the continuous casting; the content w1 of the specific component in the ladle steel liquid of the furnace after continuous casting is obtained; the content w of the component in the mixed-cast steel liquid is predicted based on the content w0 of the specific component in the tundish steel liquid, the content w1 of the specific component in the ladle steel liquid, the real-time weight p, and the amount of molten steel q in the ladle for casting. When continuously casting steel grades with different components, a simplified algorithm is used to calculate the composition of the mixed-cast billet when the weight of the tundish remains unchanged or changes. This method can quickly and accurately calculate the real-time composition of the mixed steel, is highly efficient and practical for production, and has a theoretical error close to zero.

Description

Technical Field

[0001] The invention belongs to the technical field of steelmaking, and in particular relates to a method for predicting the component content of mixed-cast molten steel. Background Art

[0002] With the diversification of market demand, there are more and more steel grades and specifications, and the number of short continuous castings has increased accordingly. There are usually three ways to continuously cast different steel grades: direct high-tonnage continuous casting is used for steel grades with little difference in composition; continuous casting is carried out by inserting iron plates or low weight for steel grades with a certain difference in composition; and continuous casting is carried out by quickly replacing the tundish for steel grades with a large difference in composition. When two steel grades with large differences in composition are continuously cast, mixed billets will be produced that do not meet the composition requirements of the previous steel grade nor the latter steel grade. Since the composition of mixed billets produced by inserting iron plates or low-tonnage continuous casting cannot be determined, the composition of the mixed billets can only be tested by sampling the billets offline. Only when it is determined that they meet the requirements of the molten steel can rolling be arranged, which will result in a large turnover capacity of the slab warehouse.

[0003] Currently, research on continuous casting composition often relies on water-based modeling and numerical simulation to simulate compositional changes during the mixed casting of different steel grades. Alternatively, regression or interpolation methods are used on industrial test data to establish mixed casting prediction models to predict compositional changes. Simulation and industrial test data fitting analysis are limited by process conditions and chemical acceptance data, making it difficult to accurately predict mixed steel composition. Furthermore, simulation tests consume significant human and material resources and cannot be quickly adapted to changing field conditions. Summary of the Invention

[0004] The present application provides a method for predicting the composition content of mixed-cast steel liquid to solve the technical problem of being unable to accurately control the real-time composition of the mixed-cast billet.

[0005] In a first aspect, the present application provides a method for predicting the composition content of mixed cast steel liquid, the method comprising the following steps:

[0006] Obtain the content w0 of specific components in the tundish steel liquid before continuous casting;

[0007] Continuously pouring the tundish molten steel, and obtaining the real-time weight p of the tundish molten steel and the amount q of molten steel in the ladle for pouring during the continuous pouring;

[0008] Obtaining the specific component content w1 in the molten steel in the ladle after continuous casting;

[0009] The content w of the component in the mixed molten steel is predicted based on the content w0 of the specific component in the tundish molten steel, the content w1 of the specific component in the ladle molten steel, the real-time weight p, and the amount q of molten steel used for pouring in the ladle.

[0010] Optionally, the calculation method of the real-time weight p of the tundish molten steel includes: iteratively calculating the average weight of the tundish molten steel at the start time and the end time.

[0011] Optionally, the calculation method of the real-time weight p of the tundish molten steel satisfies the following relationship: p=0.5*(m n-1 +m n ), where the weight of the tundish steel liquid during the nth iteration calculation is p, and the weight of the tundish steel liquid at the start of the nth iteration calculation is m n-1 At the end of the nth iteration calculation, the weight of the tundish steel liquid is m n , where n is a positive integer.

[0012] Optionally, during each iterative calculation, the weight of the tundish molten steel is kept constant.

[0013] Optionally, if the real-time weight p of the tundish molten steel is constant, the composition and content w of the mixed casting blank satisfy the following relationship:

[0014] Optionally, before the continuous casting, the thickness of the slag layer of the tundish is less than 60 mm.

[0015] Optionally, during the continuous casting process, the liquid level at the tundish molten steel outlet is greater than 100 mm.

[0016] Optionally, the specific component includes at least one of C, Si, Mn, P, S, Al, Cr, Nb, Ti, Cu, Ni, W, V and B.

[0017] Optionally, the analysis method of the specific component includes at least one of spectrophotometry, atomic spectroscopy, X-ray fluorescence spectroscopy, spark direct reading spectroscopy and carbon-sulfur analysis.

[0018] Optionally, the continuous pouring method includes at least one of high-tonnage continuous pouring, low-tonnage continuous pouring, and ultra-low-tonnage continuous pouring.

[0019] Optionally, the timing of the prediction is after the continuous pouring begins.

[0020] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0021] The method provided in the embodiment of the present application uses the tundish molten steel for continuous casting, and predicts the content w of the component in the mixed-cast molten steel based on the content w0 of the specific component in the tundish molten steel, the content w1 of the specific component in the molten steel in the ladle, as well as p and q; when continuously casting steel grades with different components, a simplified algorithm is used to calculate the composition of the mixed-cast billet when the tundish weight remains unchanged and when the tundish weight changes, which can quickly and accurately calculate the real-time composition during steel mixing, is highly efficient and practical for production, and the theoretical error is close to zero. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0024] Figure 1 A schematic flow chart of a method for predicting the composition content of mixed cast steel liquid provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0026] Throughout this specification, unless otherwise specified, the terms used herein should be understood as having the same meaning as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention belongs. In the event of a conflict, this specification takes precedence. The technical terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of the present invention. For example, room temperature may refer to a temperature within the range of 10 to 35°C.

[0027] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0028] The technical solution of the embodiment of the present application is to solve the above technical problems, and the overall idea is as follows:

[0029] According to a typical embodiment of the present invention, a method for predicting the composition content of mixed cast steel liquid is provided, such as Figure 1 As shown, the method includes the following steps:

[0030] S1 obtains the content of specific components in the tundish steel liquid before continuous casting w0;

[0031] S2. The tundish is used for continuous casting of molten steel to obtain the real-time weight p of the tundish when the continuous casting and the amount of molten steel in the ladle for pouring q;

[0032] S3 obtains the specific component content w1 in the ladle molten steel after continuous casting;

[0033] S4. Predict the content w of the component in the mixed molten steel based on the content w0 of the specific component in the tundish molten steel, the content w1 of the specific component in the molten steel in the ladle, the real-time weight p, and the amount q of molten steel in the ladle for pouring.

[0034] The method of the present application is to transfer the old ladle out after the continuous pouring front furnace is finished pouring, and at the same time transfer the new ladle to the pouring position. When the first molten steel in the tundish reaches a certain weight, the tundish water inlet slide is opened to start the ladle pouring, and the composition of the tundish is controlled in real time, so that the composition and content of the mixed casting blank can be accurately controlled.

[0035] Specifically, the data of S1 can be obtained through testing. After the continuous pouring of S3 is completed, the ladle nozzle slide can be closed and the old ladle can be transferred out. Then, in the new round, the new ladle is transferred to the pouring position, the ladle casing is connected to the ladle outlet, and the real-time weight of the new round of the intermediate ladle is obtained. Then, the ladle nozzle slide is opened to start the ladle pouring.

[0036] The tundish steel weight is the weight of the molten steel in the tundish at the moment the ladle begins pouring. The ladle pouring volume q is the difference between the actual weight of the ladle containing molten steel at the start and end of the calculation. Conventionally, molten steel in the ladle flows to the tundish, which then flows to the mold for pouring.

[0037] In some embodiments, the calculation method of the real-time weight p of the tundish molten steel includes: iteratively calculating the average weight of the tundish molten steel at the start time and the end time.

[0038] In order to reduce the error of the composition and its content and reduce the error of the composition during the iterative calculation process, the weight average of the tundish molten steel at the start time and the end time of the iterative calculation is performed.

[0039] In some embodiments, the calculation method of the real-time weight p of the tundish steel liquid satisfies the following relationship: p=0.5*(m n-1 +m n), where the weight of the tundish steel liquid during the nth iteration calculation is p, and the weight of the tundish steel liquid at the start of the nth iteration calculation is m n-1 At the end of the nth iteration calculation, the weight of the tundish steel liquid is m n , where n is a positive integer.

[0040] Specifically, the weight p of the tundish steel liquid is taken as the average of the weights of the tundish steel liquid at the start time and the end time of the iterative calculation, and it is considered that the weight of the tundish steel liquid during this iterative calculation is unchanged, that is, the amount of molten steel poured from the ladle into the tundish during the iterative calculation is equal to the amount of molten steel flowing from the tundish into the crystallizer.

[0041] In some embodiments, the real-time weight p is constant, and the composition and content w of the mixed casting satisfy the following relationship:

[0042] Specifically, the "new molten steel" flows out of the ladle into the tundish, mixes with the "old molten steel" in the tundish, and the "mixed molten steel" flows out of the tundish into the crystallizer; then the "new molten steel" flows out of the ladle into the tundish again, mixes with the "mixed molten steel" in the tundish again, and the "secondary mixed molten steel" flows out of the tundish into the crystallizer; this is repeated in sequence. The changes in the composition of the molten steel during the mixing of two molten steels with different compositions are shown in the following formula:

[0043]

[0044] Wherein, the contents of specific components of the two molten steels before mixing are c1 and c2, the corresponding weights of the mixed molten steels are m1 and m2, and the content of specific components of the molten steel after mixing is c.

[0045] Assume that the weight of the molten steel in the tundish remains constant, that is, the amount of molten steel poured from the ladle into the tundish is equal to the amount of molten steel flowing from the tundish into the crystallizer. The composition of the tundish before continuous pouring is w0, the content of the specific component in the ladle during continuous pouring is w1, and the content of the specific component after continuous pouring is w. The actual weight of the tundish is p tons, the amount of molten steel poured by the ladle during the calculation period is q tons, and the ladle pours the molten steel into the tundish evenly in n times, then:

[0046] After the first mixing, the content of a certain component in the tundish steel liquid is:

[0047]

[0048] After the second mixing, the content of a certain component in the tundish steel liquid is:

[0049]

[0050] After the third mixing, the content of a certain component in the tundish steel liquid is:

[0051]

[0052] After the nth mixing (the last one), the content of a certain component in the tundish steel liquid (mixed pouring component) is:

[0053]

[0054] make

[0055]

[0056]

[0057] When n→∞,

[0058]

[0059] The actual composition of molten steel after mixing is:

[0060] The content of components in the mixed steel liquid can be accurately predicted.

[0061] In some embodiments, before the continuous casting, the thickness of the slag layer of the tundish is less than 60 mm.

[0062] In order to ensure the smoothness of the process, the slag layer thickness of the tundish is controlled to be less than 60mm before continuous pouring. If the slag layer thickness of the tundish is too thick, the slag in the crystallizer will roll up due to the large amount of slag in the tundish after the pouring starts.

[0063] In some embodiments, during the continuous casting process, the liquid level at the tundish molten steel outlet is greater than 100 mm.

[0064] In order to control the slag rolling of molten steel, during the continuous pouring process, the liquid level at the outlet of the tundish steel liquid is greater than 100mm. If the liquid level of the tundish is too small, it is easy to cause serious slag rolling of the molten steel after the tundish pouring starts, affecting the composition and quality of the molten steel.

[0065] In some embodiments, the specific component includes at least one of C, Si, Mn, P, S, Al, Cr, Nb, Ti, Cu, Ni, W, V, and B.

[0066] Specifically, the composition of molten steel includes elements such as C, Si, Mn, P, S, Al, Cr, Nb, Ti, Cu, Ni, W, V, and B, but excludes elements such as N, H, and O. The reason for excluding N, H, and O is that their composition is less affected by continuous casting and is primarily affected by the purity of the molten steel.

[0067] In some embodiments, the assay method for the specific component comprises at least one of spectrophotometry, atomic spectroscopy, X-ray fluorescence spectroscopy, spark direct reading spectroscopy, and carbon-sulfur analysis.

[0068] In some embodiments, the continuous pouring method includes at least one of high-tonnage continuous pouring, low-tonnage continuous pouring, and ultra-low-tonnage continuous pouring.

[0069] In order to better reduce the length and weight of mixed billets and increase the number of qualified billets, different continuous casting methods are used according to the composition difference of the tundish steel liquid. If the composition difference of the tundish steel liquid is not big, direct high-tonnage continuous casting is adopted. If there is a certain difference in composition between two steel grades, low-tonnage continuous casting is adopted. If the composition difference is too big, ultra-low-tonnage continuous casting can be adopted. It is generally believed that if the composition difference is not big, the difference in all components of the two steel grades is ≤2 times, if there is a certain difference in composition, the difference in 1-2 components of the two steel grades is ≥2 times, and if the composition difference is too big, the difference in 3-6 components of the two steel grades is ≥3 times. Generally, the weight of the high-tonnage continuous casting tundish is 60-80 tons, the weight of the low-tonnage continuous casting tundish is 20-40 tons, and the weight of the ultra-low-tonnage continuous casting tundish is less than 10 tons.

[0070] In some embodiments, the predicted timing is after the continuous pouring begins.

[0071] The reason for performing composition prediction after continuous pouring is to obtain basic information, which can make the prediction results more accurate.

[0072] The method of the present invention will be described in detail below with reference to embodiments, comparative examples and experimental data.

[0073] Example

[0074] The present invention provides a method for predicting the composition content of mixed cast steel liquid, the method comprising the following steps:

[0075] Obtaining the content w0 of a specific component in the tundish molten steel before continuous pouring; obtaining the real-time weight p of the tundish molten steel during the continuous pouring; performing continuous pouring with the tundish molten steel to obtain the content w1 of the specific component in the molten steel in the ladle of the continuous pouring heat after the continuous pouring; obtaining the amount q of molten steel in the ladle for pouring; and predicting the content w of the component in the mixed-casting molten steel based on the content w0 of the specific component in the tundish molten steel, the content w1 of the specific component in the molten steel in the ladle, the real-time weight p, and the amount of molten steel q.

[0076] The calculation method of the real-time weight p of the tundish steel liquid includes: iteratively calculating the average weight of the tundish steel liquid at the start time and the end time. The calculation method of the real-time weight p of the tundish steel liquid satisfies the following relationship: p = 0.5*(m n-1 +m n ), where the weight of the tundish steel liquid during the nth iteration calculation is p, and the weight of the tundish steel liquid at the start of the nth iteration calculation is m n-1 At the end of the nth iteration calculation, the weight of the tundish steel liquid is m n, where n is a positive integer. If the real-time weight p is constant, the composition and content w of the mixed casting blank satisfy the following relationship: The components described are C, Si, Mn, P, S, Al, Cr, Nb, Ti, Cu, Ni, W, V, B and other elements in molten steel, using spectrophotometer, atomic spectroscopy, X-ray fluorescence spectroscopy, spark direct reading spectroscopy, carbon-sulfur analyzer and other methods. The thickness of the tundish slag layer is measured in the first furnace before continuous casting, and the thickness of the tundish slag layer is less than 60mm; the actual height of the tundish liquid level near the stopper rod is measured during the casting stoppage, and the height of the tundish liquid level is greater than 100mm. The weight of the tundish is taken as the average value of the weight of the tundish at the start time and the end time of the iterative calculation, and it is considered that the weight of the tundish during this iterative calculation is unchanged, that is, the amount of molten steel poured into the tundish by the ladle during the iterative calculation is equal to the amount of molten steel flowing into the crystallizer from the tundish. The formula for calculating the weight of the tundish during the iterative calculation is as follows: Among them, the weight of the tundish during the nth iteration calculation period is The weight of the intermediate package at the beginning of the nth iteration calculation is m n-1 , the weight of the intermediate package at the end of the nth iteration is m n .

[0077] Three test data were obtained by using the method of the present application to describe in detail a fast and accurate continuous pouring composition prediction method and production method of the present application. Table 1 shows the process data of three different continuous pouring tonnages.

[0078] Table 1.

[0079]

[0080] Tables 2, 3, and 4 show the simulated and actual composition results for continuous pouring times of 15, 30, and 75 tons, respectively. Tables 2, 3, and 4 represent independent experiments. When the tundish weight reaches 75 tons, it is assumed that the tundish weight no longer changes over time. During continuous pouring, each pour is separated by one minute, and the number of pours is calculated based on the continuous pouring time.

[0081] Table 2.

[0082]

[0083]

[0084] Table 3.

[0085]

[0086] Table 4.

[0087]

[0088]

[0089] From the data in Table 2, Table 3 and Table 4, it can be seen that the method of the present application can accurately control and predict the real-time composition of the tundish during continuous casting of steel grades with different compositions. The composition error of low-tonnage continuous casting is within 5%, and the error is close to zero during high-tonnage continuous casting.

[0090] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations are intended to cover non-exclusive inclusion, so that a process, method, article, or device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device that includes the element.

[0091] The foregoing description is intended only to provide specific embodiments of the present invention, which will enable those skilled in the art to understand and implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not intended to be limited to the embodiments shown herein, but is intended to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for predicting the composition content of mixed cast steel liquid, characterized in that: The method comprises the following steps: Obtain the content w0 of specific components in the tundish steel liquid before continuous casting; Continuously pouring the tundish steel liquid, obtaining a real-time weight p of the tundish steel liquid and a quantity q of molten steel in the ladle for pouring during the continuous pouring, wherein the quantity q of molten steel in the ladle for pouring is the difference between the real-time weight of the ladle containing the molten steel at the start time and the end time of the calculation; Obtaining the specific component content w1 in the molten steel in the ladle after continuous casting; Predicting the content w of the component in the mixed-cast steel liquid based on the content w0 of the specific component in the tundish molten steel, the content w1 of the specific component in the ladle molten steel, the real-time weight p, and the amount q of molten steel in the ladle for pouring; The method for calculating the real-time weight p of the tundish steel liquid comprises: iteratively calculating the average weight of the tundish steel liquid at the start time and the end time, wherein the weight of the tundish steel liquid is a constant value during each iterative calculation; The calculation method of the real-time weight p of the tundish steel liquid satisfies the following relationship: p=0.5*(m n-1 +m n ), where the weight of the tundish steel liquid during the nth iteration calculation is p, and the weight of the tundish steel liquid at the start of the nth iteration calculation is m n-1 At the end of the nth iteration calculation, the weight of the tundish steel liquid is m n , where n is a positive integer; The real-time weight p is constant, and the composition and content w of the mixed casting meet the following relationship: .

2. The method according to claim 1, characterized in that Before the continuous pouring, the thickness of the slag layer of the tundish is less than 60 mm.

3. The method according to claim 1, characterized in that During the continuous casting process, the liquid level at the tundish molten steel outlet is greater than 100 mm.

4. The method according to claim 1, wherein The specific components include at least one of C, Si, Mn, P, S, Al, Cr, Nb, Ti, Cu, Ni, W, V and B.

5. The method according to claim 1, wherein The analysis method of the specific component includes at least one of spectrophotometry, atomic spectroscopy, X-ray fluorescence spectroscopy, spark direct reading spectroscopy and carbon-sulfur analysis.

6. The method according to claim 1, characterized in that The continuous pouring method includes at least one of high-tonnage continuous pouring, low-tonnage continuous pouring, and ultra-low-tonnage continuous pouring.

7. The method according to claim 1, characterized in that The timing of the prediction is after the continuous pouring starts.

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