Method for calculating the amount of calcium wire feeding into molten steel based on the minimum Gibbs free energy method

Abstract

The present invention provides a method for calculating the amount of calcium wire fed into molten steel based on the minimum Gibbs free energy method, which relates to the calcium treatment operation process of molten steel refining in the field of iron and steel metallurgy, and includes the following steps: establishing a connection with a field database, reading the composition and temperature of the molten steel in the actual production process; calculating the composition of the inclusions in the current molten steel according to the read molten steel composition; calculating the calcium content required for the molten steel to control the inclusions in the target area under the current conditions; calculating the appropriate length of the calcium feeding line according to the current calcium feeding operation parameter information and the calcium content required for the molten steel. The present invention can provide a scientific and reasonable guidance for the calcium treatment operation in the actual production process in real time, realize the precise control of the calcium treatment operation, ensure the calcium treatment effect, improve the product quality, and ensure the stability and continuity of the actual production process.

Description

Technical Field

[0001] The invention belongs to the field of molten steel refining in iron and steel metallurgy, and in particular relates to a method for calculating the calcium wire feeding amount of molten steel based on a minimum Gibbs free energy method. Background Art

[0002] During the smelting process of molten steel, aluminum, as a strong deoxidizer, can effectively reduce the oxygen in the molten steel to a lower level. However, the addition of aluminum will generate a large amount of aluminum oxide inclusions, leading to nozzle nodules, affecting the smoothness of the continuous casting process and causing a decrease in product quality. Therefore, in most steel grades that use aluminum deoxidation, metallic calcium, which is more active than aluminum, is added to the molten steel to modify the aluminum oxide inclusions in the molten steel into liquid calcium aluminates, reducing nozzle nodules and blockage problems, ensuring smooth continuous casting, and improving product quality. At the same time, the presence of calcium in steel can also control the morphology and quantity of MnS inclusions during steel solidification, cooling and heating. However, there is a reasonable range for the amount of calcium required in steel, which cannot be too high or too low.

[0003] The reasonable calcium requirement in molten steel is related to the conditions such as molten steel temperature, molten steel composition and steel type. The calcium requirement of molten steel in different production furnaces is different. At present, almost all enterprises carry out calcium treatment operations based on experience, lacking a scientific and reasonable guidance, so the control of calcium content in steel is unstable. Therefore, based on the minimum Gibbs free energy principle, the inclusion composition and appropriate calcium content in the current molten steel are calculated, and finally the appropriate calcium feeding line length is obtained to achieve precise control of calcium treatment operations, which has important research value and significance for reducing the production and operation costs of enterprises, improving product quality and alloy utilization efficiency. Summary of the invention

[0004] In order to solve the above-mentioned deficiencies of the prior art, the present invention provides a method for calculating the calcium wire feeding amount of molten steel based on the minimum Gibbs free energy method, so as to achieve precise control of the calcium treatment operation.

[0005] Specifically, the present invention provides a method for calculating the amount of calcium wire fed into molten steel based on the minimum Gibbs free energy method, which comprises the following steps:

[0006] S1: Obtaining the steel liquid composition data before calcium treatment operation and calcium treatment operation parameter information from the production process database;

[0007] S2: Based on the minimum Gibbs free energy principle, thermodynamic calculation is performed on the molten steel composition data obtained in step S1 to obtain the current inclusion composition and the amount of calcium required for the molten steel, which specifically includes the following steps:

[0008] S21: The composition of non-metallic inclusions in molten steel is calculated based on the minimum Gibbs free energy principle. The formula used is as follows:

[0009]

[0010] In the formula, min.Gs is the minimum Gibbs free energy of the system, is the standard molar Gibbs free energy of component i, a i is the activity of component i, component i includes solid inclusion phase, liquid inclusion phase and molten steel phase, m is the component in molten steel, R is the gas constant, T is the temperature of molten steel, slag is the liquid inclusion in molten steel, solid is the solid inclusion in molten steel;

[0011] S22: Calculate the Gibbs free energy in the solid inclusion phase, liquid inclusion phase and iron liquid phase. The formula for calculating the Gibbs free energy in the solid phase is as follows:

[0012]

[0013] The formula for calculating the Gibbs free energy in liquid phase inclusions is as follows:

[0014]

[0015] The formula for calculating the Gibbs free energy in the iron liquid phase is as follows:

[0016]

[0017] Where c is the number of components in the steel-inclusion system, x is the molar fraction of the element in the molten steel, and γ is the activity coefficient of the element in the molten steel;

[0018] S23: Calculate the activity value of inclusions in the solid inclusion phase and the activity value of inclusions in the liquid inclusion phase. The activity value of inclusions in the solid inclusion phase is 1, and the activity value of inclusions in the liquid inclusion phase is calculated according to the following formula:

[0019]

[0020]

[0021] Where: is the activity of Al2O3 in liquid inclusions, a CaO is the activity of CaO in liquid inclusions, is the mass fraction of Al2O3 in liquid inclusions;

[0022] S24: Calculate the composition and content of inclusions in the molten steel. Substitute formulas (2) to (6) into formula (1) and add constraints. In the constraints, the variable input when calculating the composition of the current inclusions is the composition of the molten steel. By solving formula (1), the composition and content of the inclusions in the current molten steel are obtained, and the amount of calcium required for the molten steel is calculated under the condition that the inclusions are controlled in the liquid phase region.

[0023] S3: Calculate the calcium recovery rate: predict or calculate the calcium recovery rate during the calcium treatment process to obtain the calcium recovery rate;

[0024] S4: according to the amount of calcium required by the molten steel calculated in step S2, combined with the calcium recovery rate predicted in step S3 and the calcium treatment operation parameter information read in step S1, calculate the appropriate length of the calcium feeding line;

[0025] The formula for calculating the length of the calcium feeding line is as follows:

[0026]

[0027] Where: L is the length of the calcium feeding line, in meters; W is the weight of molten steel, in t; n[Ca] T is the amount of calcium required for the molten steel calculated according to step S2, in %; n[Ca] O is the calcium content in the molten steel before calcium treatment, in %; M Ca is the molar mass of calcium, in g / mol; M Fe is the molar mass of iron, in g / mol; η is the calcium yield, in %; β is the calcium content in the calcium wire, in %; μ is the weight of calcium wire per meter, in g / m.

[0028] Preferably, the variable input when calculating the composition of the current inclusions in step S2 is the composition of the molten steel, satisfying the following constraints:

[0029]

[0030]

[0031]

[0032] ∑n S =n [S] +n CaS (11)

[0033] Where: ∑n Ca is the total molar number of calcium in the system, n [Ca] is the number of moles of calcium dissolved in the liquid steel phase, n [Al] is the number of moles of aluminum dissolved in the liquid steel phase, n [O] is the number of moles of dissolved oxygen in the liquid steel phase, n [S] is the number of moles of sulfur dissolved in the liquid steel phase, n CaO is the molar number of CaO in the inclusions, n CaS is the molar number of CaS in the inclusions, For inclusion The number of moles, is the molar number of CaO·6Al2O3 in the inclusions, n CA2 is the molar number of CaO·2Al2O3 in the inclusions.

[0034] Preferably, the calcium treatment operation parameters in step S1 include molten steel C content, molten steel Si content, molten steel Mn content, molten steel P content, molten steel S content, molten steel Ca content, molten steel Al content, molten steel oxygen content, molten steel temperature, calcium wire weight, calcium wire calcium content and molten steel weight.

[0035] Preferably, in step S3, the calcium recovery rate can be predicted according to the current [O] content of the molten steel, or predicted according to a neural network model.

[0036] The calcium recovery rate in step S3 can be predicted based on the neural network model or based on the current molten steel [O] content. The calculation formula for predicting the oxygen content is:

[0037] y=50000*x o +10 (12)

[0038] Where: x o is the [O] content of the molten steel, and y is the yield η predicted based on the oxygen content.

[0039] Preferably, the neural network model is a shallow neural network model or a deep neural network model.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The method for calculating the amount of calcium wire fed into molten steel based on the minimum Gibbs free energy method provided by the present invention obtains the composition of molten steel and calcium treatment operation parameter information of each batch in real time, predicts the composition of inclusions in the current molten steel and the appropriate amount of calcium required in the molten steel, and finally obtains the appropriate amount of calcium wire fed in combination with the calcium content of the calcium wire, the weight per meter of the calcium wire, the yield and other operation parameter information. By calculating the composition of inclusions in steel based on the minimum Gibbs free energy principle in this model and calculating the appropriate length of calcium wire fed in the calcium treatment process, scientific and reasonable guidance of the calcium treatment operation can be achieved, the error caused by calcium feeding based on experience can be reduced, and the calcium treatment operation process can be stabilized, ensuring the smooth production of the enterprise, reducing production costs, and improving production efficiency and product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the overall process of the present invention;

[0043] Figure 2 It is a schematic flow chart of a method for calculating the amount of calcium wire fed into molten steel based on the minimum Gibbs free energy method implemented according to the present invention;

[0044] Figure 3 It is a schematic diagram of the process of calculating the composition of inclusions in steel using the minimum Gibbs free energy principle in an embodiment of the present invention;

[0045] Figure 4 Schematic diagram of the effect of calcium content in steel on inclusions calculated based on the minimum Gibbs free energy principle in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The exemplary embodiments, features and aspects of the present invention will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0047] According to an embodiment of the present invention, a method for calculating the amount of calcium wire fed into molten steel based on the minimum Gibbs free energy method is provided.

[0048] It includes the following steps:

[0049] S1: Obtaining the steel liquid composition data before calcium treatment operation and calcium treatment operation parameter information from the production process database;

[0050] S2: Based on the minimum Gibbs free energy principle, thermodynamic calculation is performed on the molten steel composition data obtained in step S1 to obtain the current inclusion composition and the amount of calcium required for the molten steel, which specifically includes the following steps:

[0051] S21: The composition of non-metallic inclusions in molten steel is calculated based on the minimum Gibbs free energy principle. The formula used is as follows:

[0052]

[0053] In the formula, min.Gs is the minimum Gibbs free energy of the system, is the standard molar Gibbs free energy of component i, a i is the activity of component i, component i includes solid inclusion phase, liquid inclusion phase and molten steel phase, m is the component in molten steel, R is the gas constant, T is the temperature of molten steel, slag is the liquid inclusion in molten steel, solid is the solid inclusion in molten steel;

[0054] S22: Calculate the Gibbs free energy in the solid inclusion phase, liquid inclusion phase and iron liquid phase. The formula for calculating the Gibbs free energy in the solid phase is as follows:

[0055]

[0056] The formula for calculating the Gibbs free energy in liquid phase inclusions is as follows:

[0057]

[0058] The formula for calculating the Gibbs free energy in the iron liquid phase is as follows:

[0059]

[0060] Where c is the number of components in the steel-inclusion system, x is the molar fraction of the element in the molten steel, and γ is the activity coefficient of the element in the molten steel;

[0061] S23: Calculate the activity value of inclusions in the solid inclusion phase and the activity value of inclusions in the liquid inclusion phase. The activity value of inclusions in the solid inclusion phase is 1, and the activity value of inclusions in the liquid inclusion phase is calculated according to the following formula:

[0062]

[0063]

[0064] Where: is the activity of Al2O3 in liquid inclusions, a CaO is the activity of CaO in liquid inclusions, is the mass fraction of Al2O3 in liquid inclusions;

[0065] S24: Calculate the composition and content of inclusions in the molten steel. Substitute formulas (2) to (6) into formula (1) and add constraints. In the constraints, the variable input when calculating the composition of the current inclusions is the composition of the molten steel. By solving formula (1), the composition and content of the inclusions in the current molten steel are obtained, and the amount of calcium required for the molten steel is calculated under the condition that the inclusions are controlled in the liquid phase region.

[0066] S3: Calculate the calcium recovery rate: predict or calculate the calcium recovery rate during the calcium treatment process to obtain the calcium recovery rate;

[0067] S4: according to the amount of calcium required by the molten steel calculated in step S2, combined with the calcium recovery rate predicted in step S3 and the calcium treatment operation parameter information read in step S1, calculate the appropriate length of the calcium feeding line;

[0068] The formula for calculating the length of the calcium feeding line is as follows:

[0069]

[0070] Where: L is the length of the calcium feeding line, in meters; W is the weight of molten steel, in t; n[Ca] T is the amount of calcium required for the molten steel calculated according to step S2, in %; n[Ca] O is the calcium content in the molten steel before calcium treatment, in %; M Ca is the molar mass of calcium, in g / mol; MFe is the molar mass of iron, in g / mol; η is the calcium yield, in %; β is the calcium content in the calcium wire, in %; μ is the weight of calcium wire per meter, in g / m.

[0071] Preferably, the variable input when calculating the composition of the current inclusions in step S2 is the composition of the molten steel, satisfying the following constraints:

[0072]

[0073]

[0074]

[0075] ∑n S =n [S] +n CaS (11)

[0076] Where: ∑n Ca is the total molar number of calcium in the system, n [Ca] is the number of moles of calcium dissolved in the liquid steel phase, n [Al] is the number of moles of aluminum dissolved in the liquid steel phase, n [O] is the number of moles of dissolved oxygen in the liquid steel phase, n [S] is the number of moles of sulfur dissolved in the liquid steel phase, n CaO is the molar number of CaO in the inclusions, n CaS is the molar number of CaS in the inclusions, is the molar number of Al2O3 in the inclusions, is the molar number of CaO·6Al2O3 in the inclusions, n CA2 is the molar number of CaO·2Al2O3 in the inclusions.

[0077] Preferably, the steel liquid composition information and operating parameters in step S1 include steel liquid C content, steel liquid Si content, steel liquid Mn content, steel liquid P content, steel liquid S content, steel liquid Ca content, steel liquid Al content, steel liquid oxygen content, steel liquid temperature, calcium line weight, calcium line calcium content, and steel liquid weight.

[0078] Preferably, the parameters required for predicting the calcium yield during the calcium treatment process in step S3 include molten steel C content, molten steel Si content, molten steel Mn content, molten steel P content, molten steel S content, molten steel Ca content, molten steel Al content, molten steel temperature, wire feeding speed, and argon blowing flow rate.

[0079] The calcium recovery rate η can be predicted and calculated by a shallow neural network or a deep neural network, or the calcium recovery rate can be predicted by the current [O] content of the molten steel.

[0080] In one embodiment, the calcium recovery rate can be predicted based on the current molten steel [O] content, and the calcium recovery rate can be directly calculated by the following formula:

[0081] y=50000*x o +10

[0082] Where: x o is the [O] content of the molten steel, and y is the yield η predicted based on the oxygen content.

[0083] In the actual calculation process, the calcium recovery rate can also be predicted and calculated by the prediction method of calcium recovery rate in calcium treatment process based on deep neural network previously applied by the applicant, which will not be repeated here. Specific embodiment 1

[0085] like Figure 2 and Figure 3 As shown, the method for calculating the amount of calcium wire fed into molten steel based on the minimum Gibbs free energy method according to an embodiment of the present invention comprises the following steps:

[0086] S1: Establish a connection with the on-site production process database to determine the composition of the molten steel before the calcium treatment operation and the calcium treatment operation parameter information: C = 0.06%, Si = 0.08%, Mn = 1.4%, P = 0.002%, S = 0.0035%, Ca = 0.0021%, Al = 0.083%, TO = 0.007%, [O] = 0.0003%, molten steel temperature T = 1873K, calcium wire weight 200g / m, calcium wire calcium content 40%, molten steel weight 100t.

[0087] S2: Based on the minimum Gibbs free energy principle, thermodynamic calculation is performed on the molten steel composition data obtained in step S1 to calculate the current inclusion composition and the appropriate calcium requirement in the steel.

[0088] S3: Predict the calcium recovery rate during calcium treatment.

[0089] S4: According to the appropriate calcium requirement in the molten steel calculated in step S2, combined with the calcium recovery rate predicted in step S3 and the operating parameter information read in step S1, the appropriate length of the calcium feeding line is calculated.

[0090] Furthermore, in step S2, the composition of non-metallic inclusions in steel is calculated based on the minimum Gibbs free energy principle, and the formula function used is as follows:

[0091]

[0092] In the formula, min.Gs is the minimum Gibbs free energy of the system, is the standard molar Gibbs free energy of component i, and the data used are shown in Table 1, ai is the activity of component i, which includes solid inclusion phase, liquid inclusion phase and liquid steel phase.

[0093] Table 1 Standard molar Gibbs free energy of each substance in the steel-inclusion system

[0094]

[0095] The formula for calculating the Gibbs free energy in the solid phase is as follows:

[0096]

[0097] The formula for calculating the Gibbs free energy in liquid phase inclusions is as follows:

[0098]

[0099] The formula for calculating the Gibbs free energy in the iron liquid phase is as follows:

[0100]

[0101] Furthermore, the activity value of inclusions in the solid inclusion phase is 1, and the activity value of inclusions in the liquid inclusion phase is calculated according to the following formula:

[0102]

[0103]

[0104] Where: is the activity of Al2O3 in liquid inclusions, a CaO is the activity of CaO in liquid inclusions, is the mass fraction of Al2O3 in liquid inclusions.

[0105] In step S2, the variable input when calculating the composition of the current inclusions is the composition of the molten steel, which satisfies the following constraints:

[0106]

[0107]

[0108]

[0109] ∑n S =n [S] +n CaS (11)

[0110] Where: ∑n Ca is the total molar number of calcium in the system, n [Ca] is the number of moles of calcium dissolved in the liquid steel phase, n[Al] is the number of moles of aluminum dissolved in the liquid steel phase, n [O] is the number of moles of dissolved oxygen in the liquid steel phase, n [S] is the number of moles of sulfur dissolved in the liquid steel phase, n CaO is the molar number of CaO in the inclusions, n CaS is the molar number of CaS in the inclusions, is the molar number of Al2O3 in the inclusions, is the molar number of CaO·6Al2O3 in the inclusions, n CA2 is the molar number of CaO·2Al2O3 in the inclusions.

[0111] Substituting formulas (2) to (6) into formula (1), and solving formula (1) using MATLAB, it is found that the current molten steel contains 0.0021% CaO·6Al2O3 and 0.0024% CaO·2Al2O3. In order to control the inclusions in the liquid phase, the required calcium content of the molten steel is 0.0018% to 0.0027%.

[0112] Furthermore, in step S3, the calcium recovery rate is predicted according to the current molten steel [O] content, and the molten steel content and the calcium recovery rate are calculated by the following formula:

[0113] y=50000*x o +10

[0114] Where: x o is the [O] content of the molten steel, and y is the yield η predicted based on the oxygen content.

[0115] The [O] content in the molten steel is 0.0003%, and the calculated calcium recovery rate is 25%.

[0116] Furthermore, the target calcium content calculated in step S2 is 0.0018%-0.0027%, and the appropriate calcium feeding line length in the current molten steel is calculated according to the following formula:

[0117]

[0118] Where: χ is the length of the calcium feeding line, m; W is the weight of molten steel, t; ω[Ca] T is the target calcium content calculated according to step S2, %; ω[Ca] O is the calcium content in the molten steel before calcium treatment, %; M Ca is the molar mass of calcium, g / mol; M Fe is the molar mass of iron, g / mol; η is the calcium yield, %; β is the calcium content in the calcium wire, %; μ is the weight of the calcium wire per meter, g / m.

[0119] According to the formula, the current suitable calcium feeding line length is: 40-70m.

[0120] Example 2

[0121] like Figure 2 As shown, the method for calculating the amount of calcium wire fed into molten steel based on the minimum Gibbs free energy method according to an embodiment of the present invention comprises the following steps:

[0122] S1: Establish a connection with the on-site production process database to determine the composition of the molten steel before the calcium treatment operation and the calcium treatment operation parameter information: C = 0.06%, Si = 0.08%, Mn = 1.4%, P = 0.002%, S = 0.0035%, Ca = 0.0020%, Al = 0.083%, TO = 0.007%, [O] = 0.0003%, molten steel temperature T = 1873K, calcium wire weight 200g / m, calcium wire calcium content 40%, molten steel weight 100t.

[0123] S2: Based on the minimum Gibbs free energy principle, thermodynamic calculation is performed on the molten steel composition data obtained in step S1 to calculate the current inclusion composition and the appropriate calcium requirement in the steel;

[0124] S3: predict the calcium recovery rate during calcium treatment;

[0125] S4: according to the appropriate calcium requirement in the molten steel calculated in step S2, combined with the calcium recovery rate predicted in step S3 and the operating parameter information read in step S1, calculate the appropriate length of the calcium feeding line;

[0126] Furthermore, in step S2, the composition of non-metallic inclusions in steel is calculated based on the minimum Gibbs free energy principle, and the formula function used is as follows:

[0127]

[0128] In the formula, min.Gs is the minimum Gibbs free energy of the system, is the standard molar Gibbs free energy of component i, and the data used are shown in Table 1, a i is the activity of component i, which includes solid inclusion phase, liquid inclusion phase and liquid steel phase.

[0129] Table 2 Standard molar Gibbs free energy of each substance in the steel-inclusion system

[0130]

[0131] The formula for calculating the Gibbs free energy in the solid phase is as follows:

[0132]

[0133] The formula for calculating the Gibbs free energy in liquid phase inclusions is as follows:

[0134]

[0135] The formula for calculating the Gibbs free energy in the iron liquid phase is as follows:

[0136]

[0137] Furthermore, the activity value of inclusions in the solid inclusion phase is 1, and the activity value of inclusions in the liquid inclusion phase is calculated according to the following formula:

[0138]

[0139]

[0140] Where: is the activity of Al2O3 in liquid inclusions, a CaO is the activity of CaO in liquid inclusions, is the mass fraction of Al2O3 in liquid inclusions.

[0141] In step S2, the variable input when calculating the composition of the current inclusions is the composition of the molten steel, which satisfies the following constraints:

[0142]

[0143]

[0144]

[0145] ∑n S =n [S] +n CaS (11)

[0146] Where: ∑n Ca is the total molar number of calcium in the system, n [Ca] is the number of moles of calcium dissolved in the liquid steel phase, n [Al] is the number of moles of aluminum dissolved in the liquid steel phase, n [O] is the number of moles of dissolved oxygen in the liquid steel phase, n [S] is the number of moles of sulfur dissolved in the liquid steel phase, n CaO is the molar number of CaO in the inclusions, n CaS is the molar number of CaS in the inclusions, is the molar number of Al2O3 in the inclusions, is the molar number of CaO·6Al2O3 in the inclusions, n CA2 is the molar number of CaO·2Al2O3 in the inclusions.

[0147] Substituting formula (2) to (6) into formula (1), the solution of formula (1) is obtained by MATLAB. It is found that all the inclusions in the current molten steel are liquid calcium aluminate. The inclusions are controlled within the target area by using the constraint conditions. The required calcium content of the molten steel is 0.0018% to 0.0027%. Figure 4 Effect of calcium content in steel on inclusions calculated according to the Gibbs free energy minimization principle.

[0148] Further, according to the method for calculating the calcium content in Example 1, the calcium content in the current molten steel is calculated to be 0.002%, which is within the range of 0.0018% to 0.0027%. Therefore, the molten steel does not need to be fed with calcium, and the appropriate calcium feeding line length is: 0m.

[0149] Finally, it should be noted that the above-described embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating the amount of calcium wire feed in molten steel based on the minimum Gibbs free energy method, characterized in that: It includes the following steps: S1: Obtaining the steel liquid composition data before calcium treatment operation and calcium treatment operation parameter information from the production process database; S2: Based on the minimum Gibbs free energy principle, thermodynamic calculation is performed on the molten steel composition data obtained in step S1 to obtain the current inclusion composition and the amount of calcium required for the molten steel, which specifically includes the following steps: S21: The composition of non-metallic inclusions in molten steel is calculated based on the minimum Gibbs free energy principle. The formula used is as follows: In the formula, min.Gs is the minimum Gibbs free energy of the system, is the standard molar Gibbs free energy of component i, a i is the activity of component i, component i includes solid inclusion phase, liquid inclusion phase and molten steel phase, m is the component in molten steel, R is the gas constant, T is the temperature of molten steel, slag is the liquid inclusion in molten steel, solid is the solid inclusion in molten steel; S22: Calculate the Gibbs free energy in the solid inclusion phase, liquid inclusion phase and iron liquid phase. The formula for calculating the Gibbs free energy in the solid phase is as follows: The formula for calculating the Gibbs free energy in liquid phase inclusions is as follows: The formula for calculating the Gibbs free energy in the iron liquid phase is as follows: Where c is the number of components in the steel-inclusion system, x is the molar fraction of the element in the molten steel, and γ is the activity coefficient of the element in the molten steel; S23: Calculate the activity value of inclusions in the solid inclusion phase and the activity value of inclusions in the liquid inclusion phase. The activity value of inclusions in the solid inclusion phase is 1, and the activity value of inclusions in the liquid inclusion phase is calculated according to the following formula: Where: is the activity of Al2O3 in liquid inclusions, a CaO is the activity of CaO in liquid inclusions, is the mass fraction of Al2O3 in liquid inclusions; S24: Calculate the composition and content of inclusions in the molten steel. Substitute formulas (2) to (6) into formula (1) and add constraints. In the constraints, the variable input when calculating the composition of the current inclusions is the composition of the molten steel. By solving formula (1), the composition and content of the inclusions in the current molten steel are obtained, and the amount of calcium required for the molten steel is calculated under the condition that the inclusions are controlled in the liquid phase region. The constraints are as follows: Where: ∑n Ca is the total molar number of calcium in the system, n [Ca] is the number of moles of calcium dissolved in the liquid steel phase, n [Al] is the number of moles of aluminum dissolved in the liquid steel phase, n [O] is the number of moles of dissolved oxygen in the liquid steel phase, n [S] is the number of moles of sulfur dissolved in the liquid steel phase, n CaO is the molar number of CaO in the inclusions, n CaS is the molar number of CaS in the inclusions, is the molar number of Al2O3 in the inclusions, is the molar number of CaO·6Al2O3 in the inclusions, n CA2 is the molar number of CaO·2Al2O3 in the inclusions; S3: Calculate the calcium recovery rate: predict or calculate the calcium recovery rate during the calcium treatment process to obtain the calcium recovery rate; S4: according to the amount of calcium required by the molten steel calculated in step S2, combined with the calcium recovery rate predicted in step S3 and the calcium treatment operation parameter information read in step S1, calculate the appropriate length of the calcium feeding line; The formula for calculating the length of the calcium feeding line is as follows: Where: L is the length of the calcium feeding line, in meters; W is the weight of molten steel, in t; n[Ca] T is the amount of calcium required for the molten steel calculated according to step S2, in %; n[Ca] O is the calcium content in the molten steel before calcium treatment, in %; M Ca is the molar mass of calcium, in g / mol; M Fe is the molar mass of iron, in g / mol; η is the calcium yield, in %; β is the calcium content in the calcium wire, in %; μ is the weight of calcium wire per meter, in g / m.

2. the method for calculating the molten steel calcium wire feeding amount based on minimum Gibbs free energy method according to claim 1, is characterized in that: The calcium treatment operation parameters in step S1 include molten steel C content, molten steel Si content, molten steel Mn content, molten steel P content, molten steel S content, molten steel Ca content, molten steel Al content, molten steel oxygen content, molten steel temperature, calcium wire weight, calcium wire calcium content and molten steel weight.

3. the method for calculating the molten steel calcium wire feeding amount based on minimum Gibbs free energy method according to claim 1, is characterized in that: The calcium recovery rate in step S3 can be predicted based on the neural network model or based on the current molten steel [O] content. The calculation formula for predicting the molten steel [O] content is: y=50000*x o +10 (12) Where: x o is the [O] content of the molten steel, and y is the yield η predicted based on the oxygen content.

4. the method for calculating the molten steel calcium wire feeding amount based on minimum Gibbs free energy method according to claim 3, is characterized in that: The neural network model is a shallow neural network model or a deep neural network model.

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