Method for determining dissolution kinetics of solute in metallurgical slag based on molecular dynamics simulation

Abstract

The invention belongs to the technical field of ferrous metallurgy, and particularly relates to a method for determining dissolution kinetics of solute in metallurgical slag based on molecular dynamics simulation, compared with a traditional experimental method, molecular dynamics simulation does not need a large number of thermal state experiments and complex detection modes, and large-scale simulation calculation can be rapidly completed on a computer. And meanwhile, various different conditions can be simulated in a short time, and superior processes and slag systems can be quickly screened out. According to the method, the reaction which is difficult to observe clearly can be visualized, the atomic trajectory behavior of the dissolution behavior, the dynamic change, the dispersion process of the solute and the like are provided, rich and accurate information is provided for research on dissolution kinetics, and the dissolution rule and the structure evolution mechanism of the solute in the high-temperature melt can be revealed. In addition, the method is high in safety, and danger possibly brought by a high-temperature experiment is avoided.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel metallurgy technology, specifically a method for determining the solute dissolution kinetics in metallurgical slag based on molecular dynamics simulation. Background Technology

[0002] Slag, a molten mixture of oxides, is widely used in the purification of molten steel during the steelmaking process. During smelting, impurities in the steel, such as P, Mn, and Si, are oxidized and adsorbed by the slag, thus separating from the molten steel. In converter steelmaking, CaO is often used to adjust the slag composition to ensure its smelting performance and dephosphorization capacity. However, the dissolution rate of added CaO in the slag has always been a factor limiting the improvement of smelting performance, as undissolved CaO cannot promote dephosphorization of the molten steel. The structural characteristics and fluidity of the refining slag determine the cleanliness of the molten steel. The slag's removal of inclusions can be divided into three stages: the transfer of inclusions to the slag / steel interface, the inclusions overcoming the surface tension of the slag interface to enter the slag, and the dissolution of inclusions in the slag. The first stage is the flotation of inclusions, mainly controlled by the reactor flow field. The second stage is the separation of inclusions from the molten steel, mainly dominated by the wettability of the slag at the interface. The third stage is the dissolution of inclusions in the slag. Due to the unique nature of high-temperature experiments, it is difficult to clarify the factors affecting the dissolution process and the dissolution mechanism. Summary of the Invention

[0003] To address the problems existing in the prior art, the main objective of this invention is to propose a method for determining the solute dissolution kinetics in metallurgical slag based on molecular dynamics simulation.

[0004] According to one aspect of the present invention, the present invention provides the following technical solution: A method for determining the solute dissolution kinetics in metallurgical slag based on molecular dynamics simulation includes the following steps: S1. Model the solute (i.e., substances that are dissolved, such as inclusions, lime, etc.) and the slag system (i.e., solvent), as well as the combination of the two. S2. Use a suitable potential function to describe the interaction between the slag system and all atoms of the solute; S3. Perform controlled molecular dynamics simulations; S4. Statistically analyze the solute distribution in the slag to determine the solute dissolution kinetics in metallurgical slag.

[0005] As described in this invention, a method for determining the solute dissolution kinetics in metallurgical slag based on molecular dynamics simulation is provided, wherein: in step S1, modeling is performed based on the composition or structure of the solute; the slag system is modeled by composition and density, and the two are combined through amorphous modeling.

[0006] As described in this invention, a method for determining the solute dissolution kinetics in metallurgical slag based on molecular dynamics simulation is provided. In step S1, after the model is built, the model calculation settings include: the boundary type of the entire dissolution model, the simulation boundary conditions, the simulation step size, the cutoff radius, etc.

[0007] As described in this invention, a method for determining the solute dissolution kinetics in metallurgical slag based on molecular dynamics simulation is provided, wherein in step S2, the potential function includes the BMH potential function, the Buckingham potential function, and other potential functions.

[0008] As described in this invention, a method for determining the solute dissolution kinetics in metallurgical slag based on molecular dynamics simulation is described, wherein in step S3, the conjugate gradient method is used to minimize energy, the system is optimized, and then relaxation and molecular dynamics simulation are performed to record atomic displacement information.

[0009] As described in this invention, a method for determining the solute dissolution kinetics in metallurgical slag based on molecular dynamics simulation includes the following steps: in step S3, the controlled molecular dynamics simulation includes: fixing the solute coordinates and forces during melting at high temperature, and fully relaxing the slag structure; then cooling at a fixed rate to a specified temperature, and after the relaxation energy stabilizes, releasing the fixation of solute forces and displacements to begin dissolution; recording the atomic trajectory information throughout the process, and performing visualization processing.

[0010] As described in this invention, a method for determining the solute dissolution kinetics in metallurgical slag based on molecular dynamics simulation is described in step S3, in which two groups are defined: solute and slag system, and the velocity and force of the solute are set to 0 before dissolution begins at the target temperature.

[0011] As described in this invention, a method for determining the solute dissolution kinetics in metallurgical slag based on molecular dynamics simulation is provided, wherein: in step S4, statistically analyzing the solute distribution in the slag includes: using the solubility coefficient R... s Statistical analysis of solute distribution: Among them, P j The distribution of a specific labeled atom in the x, y, and z directions; x i It is the i-th distribution interval; Q is a uniform distribution; t represents time; Rs represents the rate of change of the amount of solute atoms dissolved from the start of dissolution to the end of dissolution over time. The beneficial effects of this invention are as follows: This invention proposes a method for determining the dissolution kinetics of solutes in metallurgical slag based on molecular dynamics simulation. Compared with traditional experimental methods, molecular dynamics simulation eliminates the need for extensive hot-state experiments and complex detection methods, enabling rapid large-scale simulation calculations on a computer. Furthermore, it can simulate various conditions in a short time, quickly identifying advantageous processes and slag systems. This invention can visualize reactions that are difficult to observe clearly, providing atomic trajectory behavior, dynamic changes, and solute dispersion processes of dissolution behavior, offering rich and accurate information for studying dissolution kinetics and helping to reveal the dissolution patterns and structural evolution mechanisms of solutes in high-temperature melts. In addition, the method is highly safe, avoiding the dangers that may arise from high-temperature experiments. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram showing the distribution of lime of size 4 in the slag system during the dissolution process of Example 1.

[0014] Figure 2 The dissolution rate curves of lime of sizes 0-4 in Example 1 are shown.

[0015] Figure 3 This is a schematic diagram of Al2O3 before and after dissolution in Example 2.

[0016] Figure 4 The curves showing the dissolution rate of Al2O3 inclusions in the R1-R4 slag system of Example 2 are shown.

[0017] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0018] The technical solutions described below in conjunction with the embodiments will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Inclusions in steel undergo a process involving formation, aggregation and growth, buoyancy-driven or bubble-driven flotation, wetting at the slag / steel interface, and dissolution after diffusion into the slag. In actual industrial processes, this stage can last from tens to hundreds of minutes, and different types of inclusions exhibit different behaviors. Current mainstream research methods include: rotational dissolution experiments of solute rods in molten slag; calculation of dissolution equations using contraction kernel mathematical models; and observation of direct size changes of solute particles introduced into the molten slag using optical and electron microscopy. This invention addresses the difficulties in accurately observing and measuring dissolution trends using traditional methods by proposing a method that uses molecular dynamics to simulate and determine the dissolution kinetics of solutes in metallurgical slag. This method quantitatively reproduces this process at high temperatures from a three-dimensional perspective, with higher sampling frequency and faster speed, and accurately describes it using quantitative indicators. The results are consistent with the trends observed in current experimental studies. Furthermore, a dimensionless parameter is introduced, which can be used to evaluate and determine the optimal solution for various slag systems and inclusion types, thereby customizing the slag composition to control the dissolution rate.

[0020] According to one aspect of the present invention, the present invention provides the following technical solution: A method for determining the solute dissolution kinetics in metallurgical slag based on molecular dynamics simulation includes the following steps: S1. Model the solute (i.e., substances that are dissolved, such as inclusions, lime, etc.) and the slag system (i.e., solvent), as well as the combination of the two. S2. Use a suitable potential function to describe the interaction between the slag system and all atoms of the solute; S3. Perform controlled molecular dynamics simulations; S4. Statistically analyze the solute distribution in the slag to determine the solute dissolution kinetics in metallurgical slag.

[0021] Preferably, in step S1, modeling is performed based on the composition or structure of the solute; the slag system is modeled by composition and density, and the two are combined through amorphous modeling.

[0022] Preferably, in step S1, after the model is built, the setting conditions for model calculation include: the boundary type of the entire dissolution model, the simulation boundary conditions, the simulation step size, the cutoff radius, etc.

[0023] Preferably, in step S2, the potential function includes the BMH potential function, the Buckingham potential function, etc.

[0024] Preferably, in step S3, the conjugate gradient method is used to minimize energy, optimize the system, and then relaxation and molecular dynamics simulations are performed to record atomic displacement information.

[0025] Preferably, in step S3, the controlled molecular dynamics simulation includes: fixing the solute coordinates and forces during melting at high temperature, and fully relaxing the slag structure; then cooling at a fixed rate to a specified temperature, and releasing the fixation of solute forces and displacements after the relaxation energy stabilizes, and starting dissolution; recording the atomic trajectory information throughout the process, and performing visualization processing.

[0026] Preferably, in step S3, two groups are defined: solute and slag system. Before dissolution begins at the target temperature, the rate and force of the solute are set to 0.

[0027] Preferably, in step S4, the statistical analysis of solute distribution in the slag includes: using the solubility coefficient R s Statistical analysis of solute distribution: Among them, P j The distribution of a specific labeled atom in the x, y, and z directions; x i It is the i-th distribution interval; Q is a uniform distribution; t represents time; Rs represents the rate of change of the amount of solute atoms dissolved from the start of dissolution to the end of dissolution over time. The technical solution of this invention will be further explained below with reference to specific embodiments.

[0028] Example 1 This embodiment uses R S Describe the dissolution rate variation behavior of lime of different sizes in converter slag.

[0029] First, a common CaO-SiO2-FeO converter slag structure was constructed using the amorphous cell module in Materials Studio, with a cell size of approximately 40 Å × 40 Å × 40 Å. Then, CaO atoms with the same total number of atoms but different sizes and atomic numbers were added to the slag, numbered from smallest to largest as Size0-Size4. A data file was output. The data file includes the atom number, charge number, and the three-dimensional Cartesian coordinates of the atoms.

[0030] The model is set to periodic boundaries with a step size of 1 fs and a cutoff radius of 10 Å. The interatomic interactions are described using the BMH potential function: It includes long-range Coulomb potentials, short-range repulsive potentials, and van der Waals attraction and repulsion.

[0031] After energy minimization, the structure was first relaxed at 5000 K under the NPT ensemble for 0.5 ns, during which the force and displacement of the fixed CaO were zero. After sufficient relaxation, the melt was cooled to the target temperature of 1923 K within 400 ps. Then, after relaxing at 1923 K for 100 ps, ​​the force and displacement constraints on the CaO were released, and dissolution began. Atomic coordinates were recorded during the dissolution process for subsequent calculations. A schematic diagram of the dissolution process of size 4 lime in the slag is shown below. Figure 1 As shown, by Figure 1 As can be seen, over time, the distribution of lime in the slag gradually changes from an initially dense distribution to a gradually more uniform distribution. The resulting dissolution rate change curve is shown in the figure. Figure 2 As shown, the initial dissolution rate of lime of size 4 changed the fastest, initially reaching -5.73 × 10⁻⁶. -4 .

[0032] Example 2 This embodiment uses R S Describe the dissolution rate variation behavior of different types of inclusions in refining slag.

[0033] First, a common CaO-MgO-Al₂O₃-SiO₂ refining slag structure was constructed using the amorphous cell module in Materials Studio, with basicities ranging from 2 to 10. The total number of atoms in the cell was approximately 10,000. Then, Al₂O₃ inclusions with the same number of atoms were added to the slag, numbered R1-R4 from lowest to highest basicity. A data file was output, including atom numbers, charge numbers, and the three-dimensional Cartesian coordinates of the atoms. The model was set to periodic boundaries with a step size of 1 fs and a cutoff radius of 10 Å. The Buckingham potential function was used to describe the interatomic interactions. After minimizing the energy at 0 K, the structure was first relaxed at 4000 K under the NPT ensemble for 1 ns, during which the forces and displacements of Al2O3 were fixed to zero. After sufficient relaxation, the melt was cooled to the target temperature of 1873 K within 300 ps. Then, after relaxing at 1873 K for 150 ps, ​​the force and displacement constraints on Al2O3 were released, and dissolution began. Atomic coordinates were recorded during the dissolution process for subsequent calculations. A schematic diagram of the alumina inclusions before and after dissolution is shown below. Figure 3 As shown, we hide the slag atoms in the box, leaving only the marked inclusions. Figure 3 The left side shows a schematic diagram of the alumina inclusions initially placed in the slag system, and the right side shows a schematic diagram of the alumina inclusions distribution after complete dissolution and homogeneity in the slag system box. The dissolution rate change curve is shown below. Figure 4 As shown, R4 exhibits the fastest initial dissolution rate change, initially at -0.00158.

[0034] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for determining the solute dissolution kinetics in metallurgical slag based on molecular dynamics simulation, characterized in that, Includes the following steps: S1. Model the solute and the slag system, as well as the combination of the two; S2. The potential function describing the slag system is used to describe the interactions between solutes and the interactions between atoms of slag system components; S3. Perform controlled molecular dynamics simulations; S4. Statistically analyze the solute distribution in the slag to determine the solute dissolution kinetics in metallurgical slag.

2. The method for determining the solute dissolution kinetics in metallurgical slag based on molecular dynamics simulation according to claim 1, characterized in that, In step S1, modeling is performed based on the composition or structure of the solute; the slag system is modeled by composition and density, and the two are combined through amorphous modeling.

3. The method for determining the solute dissolution kinetics in metallurgical slag based on molecular dynamics simulation according to claim 1, characterized in that, In step S1, after the model is built, the settings for model calculation include: the boundary type of the entire dissolution model, the simulation boundary conditions, the simulation step size, and the cutoff radius.

4. The method for determining the solute dissolution kinetics in metallurgical slag based on molecular dynamics simulation according to claim 1, characterized in that, In step S2, the potential function includes the BMH potential function and the Buckingham potential function.

5. The method for determining the solute dissolution kinetics in metallurgical slag based on molecular dynamics simulation according to claim 1, characterized in that, In step S3, the conjugate gradient method is used to minimize energy and optimize the system. Then, relaxation and molecular dynamics simulations are performed to record atomic displacement information.

6. The method for determining the solute dissolution kinetics in metallurgical slag based on molecular dynamics simulation according to claim 5, characterized in that, In step S3, the controlled molecular dynamics simulation includes: fixing the solute coordinates and forces during melting at high temperature, and fully relaxing the slag structure; then cooling at a fixed rate to a specified temperature, and after the relaxation energy stabilizes, releasing the fixation of solute forces and displacements to begin dissolution; recording the atomic trajectory information throughout the process and performing visualization processing.

7. The method for determining the solute dissolution kinetics in metallurgical slag based on molecular dynamics simulation according to claim 6, characterized in that, In step S3, two groups are defined: solute and slag system. Before dissolution begins at the target temperature, the rate and force of the solute are set to 0.

8. The method for determining the solute dissolution kinetics in metallurgical slag based on molecular dynamics simulation according to claim 1, characterized in that, In step S4, the statistical distribution of solute in the slag includes: using the solubility coefficient R s Statistical analysis of solute distribution: Among them, P j The distribution of a specific labeled atom in the x, y, and z directions; x i It is the i-th distribution interval; Q is a uniform distribution; t represents time; Rs is the relationship between the rate of change of the amount of solute atoms dissolved from the beginning of dissolution to the end of dissolution and time.

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