A method and system for predicting converter end point dephosphorization rate and molten steel phosphorus content

Abstract

This invention provides a method and system for predicting the final dephosphorization rate and phosphorus content of molten steel in a converter. The method includes: deriving a phosphorus distribution coefficient based on the chemical reaction formulas during the converter smelting process; constructing a prediction model for the final phosphorus content of molten steel based on the phosphorus distribution coefficients; and inputting slag sample composition, molten iron phosphorus content, tapping rate, and final temperature into the prediction model to obtain the final phosphorus content of the molten steel. This invention constructs a prediction model for the final phosphorus content of molten steel through the chemical reaction formulas during the converter smelting process and uses this model to determine the final phosphorus content of the molten steel. This can guide operators in determining the final situation, enabling them to adjust the smelting process in a timely manner and improve the accuracy of the final component determination.

Description

Technical Field

[0001] The invention relates to the technical field of iron and steel metallurgy, and in particular to a method and system for predicting a converter end point dephosphorization rate and a phosphorus content in molten steel. Background Art

[0002] The converter smelting process is a complex system with multiple factors, multiple levels and multiple objectives. There are many influencing factors, the interactions are intricate and the smelting cycle is short. In this short period of time, the basic tasks such as slag making, dephosphorization, decarbonization, desulfurization, deoxidation, degassing, deinclusion and heating must be completed, and the blowing process temperature and the terminal temperature must be properly controlled to achieve the best smelting effect. In the converter smelting process, the converter smelting situation can only be judged through a limited number of temperature measurements and sampling, while the specific conditions of the physical and chemical reactions in the furnace are unknown. In order to predict the terminal phosphorus content of this complex process, it is necessary to establish a mathematical model of the smelting process, but due to the complexity of the converter smelting process, the existing prediction models generally have low prediction accuracy. Summary of the invention

[0003] In order to overcome the deficiencies of the prior art, the object of the present invention is to provide a method and system for predicting the final dephosphorization rate of a converter and the phosphorus content of molten steel.

[0004] To achieve the above target area, the present invention provides the following solutions:

[0005] A method for predicting the final dephosphorization rate of a converter and the phosphorus content of molten steel, comprising:

[0006] The phosphorus distribution coefficient is derived from the chemical reaction formula in the converter smelting process;

[0007] Constructing a prediction model for the phosphorus content in molten steel at the converter endpoint based on the phosphorus distribution coefficient;

[0008] The slag sample composition, molten iron phosphorus content, steel output and terminal temperature are input into the converter terminal molten steel phosphorus content prediction model to obtain the terminal molten steel phosphorus content.

[0009] Preferably, the phosphorus distribution coefficient is:

[0010]

[0011] in, are the mass percentages of 3CaO·P2O5 and 4CaO·P2O5 in the slag system respectively, and ω([P]) is the mass fraction of phosphorus in molten steel.

[0012] Preferably, the prediction model for the phosphorus content of molten steel at the converter endpoint is:

[0013]

[0014] Wherein, (CaO%) represents the percentage of calcium oxide in the slag sample, (MnO%) represents the percentage of manganese oxide in the slag sample, (MgO%) represents the percentage of magnesium oxide in the slag sample, (P2O5%) represents the percentage of phosphorus pentoxide in the slag sample, Fe% represents the percentage of iron in the slag sample, T represents the final molten steel temperature, P 总 It represents the phosphorus content of molten iron, and W represents the quality of molten iron.

[0015] The present invention also provides a system for predicting the final dephosphorization rate of a converter and the phosphorus content of molten steel, comprising:

[0016] Phosphorus distribution coefficient module, used to derive the phosphorus distribution coefficient according to the chemical reaction formula in the converter smelting process;

[0017] A prediction model building module, used to build a prediction model for phosphorus content in molten steel at the converter endpoint using the phosphorus distribution coefficient;

[0018] The molten steel phosphorus content calculation module is used to input slag sample composition, molten iron phosphorus content, steel output and terminal temperature into the converter terminal molten steel phosphorus content prediction model to obtain the terminal molten steel phosphorus content.

[0019] The present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps in the above-mentioned method for predicting the final dephosphorization rate of a converter and the phosphorus content of molten steel.

[0020] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0021] The present invention constructs a prediction model for the phosphorus content of molten steel at the converter endpoint through a chemical reaction formula in the converter smelting process, and uses the prediction model to complete the determination of the phosphorus content of the molten steel at the endpoint, which can guide the operator on the endpoint situation, enable the operator to adjust the smelting process in time, and improve the hit rate of the endpoint component. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0023] Figure 1 A schematic diagram of a slag composition database of a prediction model provided by the present invention;

[0024] Figure 2 The calculation principle diagram of the prediction model provided by the present invention;

[0025] Figure 3 The present invention provides a flow chart of a method for predicting the final dephosphorization rate of a converter and the phosphorus content of molten steel. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0028] The terms "first", "second", "third" and "fourth" in the specification and claims of the present application and the drawings are used to distinguish different objects rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a series of steps, processes, methods, etc. are not limited to the listed steps, but may optionally include steps that are not listed, or may optionally include other step elements inherent to these processes, methods, products or devices.

[0029] In order to make the above-mentioned target areas, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0030] See also Figure 1-3 , a method for predicting the final dephosphorization rate of a converter and the phosphorus content of molten steel, comprising:

[0031] Step 1: Derivation of the phosphorus distribution coefficient based on the chemical reaction formula in the converter smelting process;

[0032] Step 2: constructing a prediction model for the phosphorus content of molten steel at the converter endpoint based on the phosphorus distribution coefficient;

[0033] In practical applications, phosphorus exists in steel mainly in the form of Fe3P and Fe2P phosphides. For convenience, they are usually represented by [P]. Molecular theory believes that the dephosphorization reaction in steelmaking mainly occurs on the contact surface between the molten metal and the slag. First, phosphorus is oxidized to phosphorus pentoxide, and then reacts with calcium oxide to form relatively stable phosphates. The specific reaction is as follows:

[0034] FeO=[Fe]+[O]

[0035] 2[P]+5[O]=P2O5

[0036] P2O5+4CaO=4CaO·P2O5

[0037] The overall reaction is: 2[P]+5FeO+4CaO=4CaO·P2O5+5[Fe]

[0038] According to the principle of chemical equilibrium, when the FeO and CaO contents increase, the equilibrium moves to the right, and the content of the end point [P] will decrease. Because the dephosphorization reaction is an exothermic reaction, appropriately lowering the temperature is also beneficial to the positive reaction. In order to enhance the dephosphorization capacity of the converter, it is necessary to appropriately increase the FeO content, increase the CaO (slag basicity) content, and appropriately lower the temperature to facilitate the dephosphorization reaction.

[0039] From the dephosphorization reaction of slag, it can be seen that appropriately increasing the CaO content can improve the dephosphorization ability of slag. CaO·P2O5 is relatively stable, but too high CaO content will make the slag sticky, affect the fluidity of the slag, weaken the dephosphorization reaction and be unfavorable to dephosphorization. In production practice, the dephosphorization effect is better when the slag basicity is generally controlled at around 3. Therefore, in the early stage of smelting, it is necessary to melt the slag when the temperature is low to form an early slag with a certain basicity and good fluidity.

[0040] FeO plays two important roles in slag. One is to act as an oxidant to oxidize phosphorus, and the other is to combine with phosphorus compounds to form CaO·P2O5. CaO·P2O5 is unstable at high temperatures, which is also related to the CaO content. When the alkalinity is appropriate, CaO·P2O5 will generate stable CaO·P2O5 with CaO, so that dephosphorization can be effective. The FeO content cannot be too high or too low. When it is too high, CaO will be diluted and affect dephosphorization. When it is too low, CaO cannot be fully melted, and insufficient alkalinity will affect dephosphorization, causing the slag to dry out. Therefore, the FeO content in the slag must be controlled in the three processes before, during and after converter smelting to ensure the smooth removal of phosphorus to meet the requirements of the steel grade.

[0041] Under the support of the above theory, based on the reaction between CaO, FeO and molten iron P in the converter smelting process, the reaction equations are shown in formula (1) and formula (2):

[0042]

[0043]

[0044] Combined with the dephosphorization reaction formula, the phosphorus distribution coefficient is derived:

[0045]

[0046] is the mass percentage of P2O5 in the 3CaO·P2O5 and 4CaO·P2O5 slag system components, and ω([P]) is the mass fraction of P in molten steel. The present invention combines the activity factor of dephosphorization reaction, theoretical calculation of phosphorus distribution ratio in slag, theoretical calculation of converter material balance and actual production data analysis to develop a prediction model for the terminal dephosphorization rate and the phosphorus content of molten steel at the converter terminal.

[0047] Step 3: Inputting slag sample composition, molten iron phosphorus content, steel output and terminal temperature into the converter terminal molten steel phosphorus content prediction model to obtain the terminal molten steel phosphorus content.

[0048] The present invention will be further described below in conjunction with specific embodiments:

[0049] The invention consists of two parts: a slag composition database and a calculation prediction model. Figure 1 The following table shows part of the slag composition database. The database is used to accumulate the slag laboratory test composition data and adjust the model activity coefficient. Figure 2 The following is a prediction model edited with an Excel editor, and the data formula is embedded in the table. In the prediction model, the four values ​​of slag composition, molten iron phosphorus content, steel tapping, and terminal temperature can be manually modified. In actual production, the operator enters the three data of molten iron phosphorus content, steel tapping, and terminal temperature according to the molten iron test composition. The slag composition column is the data accumulation value, and a weighted calculation is performed on the database. It can be modified or not modified according to the laboratory test value. Before the start of each furnace smelting, after entering the four values ​​of slag composition, molten iron phosphorus content, steel tapping, and terminal temperature, the calculation result will automatically output the predicted terminal molten steel phosphorus content value.

[0050] The specific calculation formula is:

[0051] The total amount of phosphorus introduced into the molten iron 总 (The element is the percentage of phosphorus in molten iron):

[0052] P 总 =W[molten iron mass / ton]×[P%]

[0053] J 权 Calculation of weighted value of phosphorus distribution ratio (elements are percentages of elements in slag):

[0054] J 权 =(CaO%)+0.6×(MnO%)+0.15×(MgO%)+0.6×(P2O5%)

[0055] Calculation of slag composition Phosphorus distribution ratio between slag and molten iron lgL p(Element is the percentage of element in slag, T is the final molten steel temperature ℃):

[0056] lgL p =11570 / (T+273)-10.5+0.072×J 权 +2.5×lg(TFe%)

[0057] lgL in the formula calculation p Perform antilogarithmic function calculation, L p

[0058] Calculate the remaining P content P in molten steel after dephosphorization reaction under the slag composition system 反 :

[0059] P 反 =P 总 / (1+0.1×L p )

[0060] The calculation expression of the prediction value model of the final molten steel P content P (%):

[0061] P(%)=P 反 / (W[molten iron mass / ton]×1000)%

[0062] The present invention uses the above prediction model to carry out calculation tests on five converters of 120t and 150t, and compares the endpoint conditions by on-site sampling and testing. The results are shown in Table 1 below.

[0063] Table 1 Production data statistics

[0064]

[0065] According to the production data of 5 converters, a total of 2077 furnaces were produced, of which 1758 furnaces used the one-time carbon pulling process and the prediction model, accounting for 84.62% of the total production. Among them, the endpoint was hit once (the phosphorus deviation between the predicted value and the test value was ≤0.003%) for 1679 furnaces, accounting for 95.51%, and the endpoint was not blown at the right time for 79 furnaces, accounting for 4.49% of the number of furnaces used. The actual production application proves that the prediction model can accurately predict the phosphorus content of the endpoint molten steel up to more than 95%, which provides a theoretical basis for improving the endpoint hit rate in the steelmaking process.

[0066] The present invention also provides a system for predicting the final dephosphorization rate of a converter and the phosphorus content of molten steel, comprising:

[0067] Phosphorus distribution coefficient module, used to derive the phosphorus distribution coefficient according to the chemical reaction formula in the converter smelting process;

[0068] A prediction model building module, used to build a prediction model for phosphorus content in molten steel at the converter endpoint using the phosphorus distribution coefficient;

[0069] The molten steel phosphorus content calculation module is used to input slag sample composition, molten iron phosphorus content, steel output and terminal temperature into the converter terminal molten steel phosphorus content prediction model to obtain the terminal molten steel phosphorus content.

[0070] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0071] The present invention constructs a prediction model for the phosphorus content of molten steel at the converter endpoint through a chemical reaction formula in the converter smelting process, and uses the prediction model to complete the determination of the phosphorus content of the molten steel at the endpoint, which can guide the operator on the endpoint situation, enable the operator to adjust the smelting process in time, and improve the hit rate of the endpoint component.

[0072] The present invention also provides a computer-readable storage medium having a computer program stored thereon, characterized in that the computer program, when executed by a processor, implements the steps in the above-mentioned method for predicting the dephosphorization rate of a converter end point and the phosphorus content of molten steel. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided by the present invention are the same as the beneficial effects of the method for predicting the dephosphorization rate of a converter end point and the phosphorus content of molten steel described in the above-mentioned technical solution, which will not be described in detail here.

[0073] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the method disclosed in the embodiment, since it corresponds to the device disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the device part description.

[0074] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for predicting the final dephosphorization rate of a converter and the phosphorus content of molten steel, characterized in that: include: The phosphorus distribution coefficient is derived from the chemical reaction formula in the converter smelting process; The phosphorus partition coefficient is: in, are the mass percentages of 3CaO·P2O5 and 4CaO·P2O5 in the slag system, respectively; ω([P]) is the mass fraction of phosphorus in molten steel; Constructing a prediction model for the phosphorus content in molten steel at the converter endpoint based on the phosphorus distribution coefficient; The prediction model for the phosphorus content of molten steel at the converter end point is: Wherein, (CaO%) represents the percentage of calcium oxide in the slag sample, (MnO%) represents the percentage of manganese oxide in the slag sample, (MgO%) represents the percentage of magnesium oxide in the slag sample, (P2O5%) represents the percentage of phosphorus pentoxide in the slag sample, Fe% represents the percentage of iron in the slag sample, T represents the final molten steel temperature, P 总 represents the phosphorus content of molten iron, W represents the mass of molten iron, and P (%) represents the phosphorus content of molten steel at the end point; The slag sample composition, molten iron phosphorus content, steel output and terminal temperature are input into the converter terminal molten steel phosphorus content prediction model to obtain the terminal molten steel phosphorus content.

2. A system for predicting the final dephosphorization rate of a converter and the phosphorus content of molten steel, characterized in that: include: Phosphorus distribution coefficient module, used to derive the phosphorus distribution coefficient according to the chemical reaction formula in the converter smelting process; The phosphorus partition coefficient is: in, are the mass percentages of 3CaO·P2O5 and 4CaO·P2O5 in the slag system, respectively; ω([P]) is the mass fraction of phosphorus in molten steel; A prediction model building module, used to build a prediction model for phosphorus content in molten steel at the converter endpoint using the phosphorus distribution coefficient; The prediction model for the phosphorus content of molten steel at the converter end point is: Wherein, (CaO%) represents the percentage of calcium oxide in the slag sample, (MnO%) represents the percentage of manganese oxide in the slag sample, (MgO%) represents the percentage of magnesium oxide in the slag sample, (P2O5%) represents the percentage of phosphorus pentoxide in the slag sample, Fe% represents the percentage of iron in the slag sample, T represents the final molten steel temperature, P 总 represents the phosphorus content of molten iron, W represents the mass of molten iron, and P (%) represents the phosphorus content of molten steel at the end point; The molten steel phosphorus content calculation module is used to input slag sample composition, molten iron phosphorus content, steel output and terminal temperature into the converter terminal molten steel phosphorus content prediction model to obtain the terminal molten steel phosphorus content.

3. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for predicting the final dephosphorization rate of a converter and the phosphorus content of molten steel as claimed in claim 1 are implemented.

Images