Steel smelting process

Abstract

The invention provides a steel smelting process which comprises the following steps: S1, deeply deoxidizing and desulfurizing molten steel to enable the oxygen content and the sulfur content in the molten steel to reach preset values respectively; s2, reducing slag is removed, dephosphorization slag is additionally made, and the dephosphorization slag is CaC2, CaF2 and CaO; s3, maintaining a reducing atmosphere above the slag layer, immediately putting a sealing cover above the slag layer after the dephosphorized slag is formed into slag, introducing argon into the cover to expel air, maintaining micro-positive pressure in the cover, and preventing air from permeating; s4, a dephosphorization reaction is carried out on a slag steel interface, the furnace temperature is adjusted to 1500-1550 DEG C, and dephosphorization is carried out at the temperature of 1500-1550 DEG C for a certain time; and S5, after the preset dephosphorization purpose is achieved, the protective cover is moved away, oxygen blowing is conducted on the slag layer, then a proper amount of silica sand (SiO2) is added into the slag layer to destroy Ca3P2 in the slag, and slag removal and pouring are conducted immediately. The method can effectively control the generation and treatment of the dephosphorization product Ca3P2, and effectively reduces the phosphorus content in the molten steel and improves the quality of the molten steel by using the CaC2-CaF2 to cover the slag dephosphorization process.

Description

Technical Field

[0001] The invention relates to the technical field of steel smelting, and in particular to a steel smelting process. Background Art

[0002] In modern industrial society, steel is one of the basic materials. The progress of steel smelting technology is not only related to the improvement of steel quality, but also directly affects production efficiency, cost control, environmental protection and other aspects. Among the many smelting processes, the deoxidation process is a key step to ensure the quality of the final steel. The purpose of the deoxidation process is to remove dissolved oxygen in the molten steel to prevent the formation of oxide inclusions in the subsequent processing, thereby affecting the mechanical properties and performance of the steel.

[0003] Traditional deoxidation methods usually include the use of silicon-calcium alloys, aluminum, manganese and other elements as deoxidizers. These elements react with oxygen in the molten steel to generate stable oxides, thereby achieving the purpose of deoxidation. However, these traditional methods have some obvious shortcomings. First, the deoxidation rate is slow, which will significantly reduce production efficiency in large-scale production. Secondly, these methods also face challenges in controlling inclusions. The presence of inclusions will seriously affect the mechanical properties and processing properties of steel. For example, although silicon-calcium alloys can effectively eliminate the adverse effects of Al2O3 inclusions, their deoxidation rate is not fast enough, which to a certain extent limits the improvement of production efficiency.

[0004] In order to overcome these shortcomings, the introduction of silicon-calcium-aluminum alloys has alleviated the problem of slow deoxidation to a certain extent. Silicon-calcium-aluminum alloys usually contain 25% silicon, 18% to 22% calcium and 18% to 22% aluminum. The use of this alloy can improve the deoxidation efficiency and have a positive effect on the morphology of inclusions in the molten steel. However, silicon-calcium-aluminum alloys still face some technical challenges in practical applications, such as the instability of deoxidation efficiency and high requirements for molten steel temperature.

[0005] In recent years, the method of using silicon-barium alloy to deoxidize steel in an induction furnace has attracted attention. Studies have shown that silicon-barium alloy can significantly reduce the total oxygen content in steel and help refine the grains, thereby improving the impact toughness of steel. Furthermore, the use of silicon-calcium-aluminum-barium alloy further improves the deoxidation effect, making the inclusion morphology in the steel more stable, especially the MnS inclusions almost completely disappear, which undoubtedly further improves the overall performance of the steel.

[0006] Although existing deoxidation technologies have made some progress, they still need to be further improved to meet the growing needs of the industry. How to further speed up the deoxidation process, reduce production costs, and reduce environmental pollution are all challenges that need to be urgently addressed in the current steelmaking industry.

[0007] The present invention proposes an innovative steelmaking process, aiming to provide a more efficient, environmentally friendly and economical steelmaking method. The process not only focuses on increasing the deoxidation rate and controlling inclusions, but also focuses on the sustainability and economic benefits of the entire production process. Summary of the invention

[0008] The purpose of the present invention is to provide a steel smelting process to solve the traditional deoxidation method in the prior art, which uses silicon-calcium alloy, aluminum, manganese and other elements for deoxidation treatment. Traditional methods often have some common defects, including slow deoxidation speed, unstable deoxidation efficiency, and environmental pollution. Through the steel smelting process of the present invention, the above problems can be effectively overcome, the efficiency and stability of the deoxidation process can be improved, and the negative impact on the environment can be reduced.

[0009] To achieve the above object, the present invention provides the following technical solution: The present invention provides a steel smelting process, which is innovative and has excellent performance in improving the quality of molten steel. It includes the following steps:

[0010] S1. In order to ensure the quality of molten steel, it is necessary to carry out deep deoxidation and desulfurization treatment on the molten steel, the purpose of which is to reduce the oxygen content and sulfur content in the molten steel to a predetermined value. This process is crucial to ensure the quality of the final product, because excessive oxygen and sulfur content will seriously affect the mechanical properties and corrosion resistance of the steel.

[0011] S2. After deoxidation and desulfurization, it is necessary to remove the reducing slag and produce dephosphorization slag, which is mainly composed of CaC2, CaF2, CaO and other components. The production of dephosphorization slag is based on the needs of specific chemical reactions to ensure that phosphorus in the molten steel can be effectively removed in the next step.

[0012] S3. Maintain a reducing atmosphere in the space above the slag layer. Once the dephosphorization slag is formed, immediately place a sealed cover above the slag layer, and introduce argon gas into the cover to drive out the air and maintain a slightly positive pressure state in the cover. This can effectively prevent the infiltration of air, thereby preventing the oxidation of the molten steel and ensuring the smooth progress of the smelting process.

[0013] S4. Dephosphorization reaction is carried out at the slag-steel interface by adjusting the furnace temperature to 1500-1550℃ and maintaining it at this temperature for a period of time to achieve the purpose of dephosphorization. High temperature is necessary because it can accelerate the dephosphorization reaction and thus improve production efficiency.

[0014] S5. Once the desired dephosphorization effect is achieved, the protective cover is removed, oxygen is blown into the slag layer, and then an appropriate amount of silica sand (SiO2) is added to the slag layer to destroy the Ca3P2 in the slag, followed by immediate slag removal and pouring. This step is the finishing touch of the entire smelting process, ensuring the purity and quality of the final product.

[0015] Preferably, in step S1, when the oxygen content and sulfur content of the molten steel reach about 0.002% and 0.001% respectively, desulfurization treatment is started. This optimization measure helps to more accurately control the desulfurization process, thereby improving the purity of the molten steel.

[0016] Preferably, the composition ratio of the dephosphorization slag in step S2 is CaC2 20% to 40%, CaF2 20% to 30%, and CaO 10% to 15%. By accurately controlling the composition ratio of the dephosphorization slag, the dephosphorization effect can be further optimized to ensure the reduction of phosphorus content in the molten steel.

[0017] Regarding the decomposition reaction of CaC2 in dephosphorization slag, the chemical equation is:

[0018] (CaC2) = {Ca} + 2[C]

[0019] △G°=63700=34.05T.

[0020] The carbon produced by this decomposition reaction is absorbed by the molten steel, while the calcium participates in the reaction with phosphorus. This process is an integral part of the dephosphorization process, which helps to separate phosphorus from the molten steel.

[0021] The chemical equation for the chemical reaction between calcium and phosphorus in molten steel is:

[0022] 3{Ca}+2[p]=[Ca3P2]

[0023] △G°=-284141+134.90T.

[0024] The dephosphorization product Ca3P2 will float up and dissolve into the slag. This reaction is the core of the dephosphorization process and directly leads to the removal of phosphorus.

[0025] Dephosphorization is achieved by removing the Ca3P2-containing slag from the furnace. This step ensures that the molten steel no longer contains harmful phosphorus, thereby improving the quality of the steel.

[0026] In order to prevent Ca3P2 from contacting with water vapor to produce harmful gas PH3, the slag containing Ca3P2 needs to be oxidized. The chemical equation for oxidation treatment is:

[0027] Ca3P2+402=P205+3CaO

[0028] Through this chemical reaction, the Ca3P2 in the slag can be converted into more stable compounds, thereby preventing the generation of harmful gases and ensuring the safety of the smelting process.

[0029] The present invention has at least the following beneficial effects:

[0030] Effectively control the generation and treatment of dephosphorization product Ca3P2. In the slag, Ca3P2 will float and dissolve, and then undergo oxidation treatment to convert Ca3P2 in the slag into P2O5 and CaO, thereby avoiding the risk of Ca3P2 coming into contact with water vapor to produce harmful gas PH3. The CaC2-CaF2 covered slag dephosphorization process significantly reduces the phosphorus content in the molten steel and improves the quality of the molten steel. Since a reducing atmosphere is maintained above the slag layer, the carbon increase phenomenon of the molten steel during the dephosphorization process is reduced. This process is suitable for the dephosphorization of high-carbon and high-chromium molten steel, expanding the application field of the dephosphorization process.

[0031] The present invention improves the purity and quality of steel. By carrying out dephosphorization reaction within a specific temperature range, phosphorus in molten steel can be removed more efficiently while maintaining the stability of other chemical components of the molten steel. The present invention not only improves production efficiency and reduces production costs, but also achieves a dual improvement in environmental protection and economic benefits by reducing the emission of harmful gases and improving the quality of molten steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A flow chart provided for the present invention. DETAILED DESCRIPTION

[0033] Unless otherwise specifically defined in this specification, all technical and scientific terms mentioned should be understood to be consistent with the meanings generally understood by professionals in the technical field related to the present invention. In the specification of the present invention, the terms used are mainly for the purpose of describing specific embodiments in detail and should not be interpreted as any limitation of the present invention. In addition, the term "and / or" in this specification is intended to include all possible combinations of any one or more items in the listed items, whether individually or collectively.

[0034] Example

[0035] like Figure 1 As shown, a steel smelting process may include the following steps:

[0036] S1. In order to ensure the quality of molten steel, it is necessary to carry out deep deoxidation and desulfurization treatment on the molten steel, with the aim of reducing the oxygen content and sulfur content in the molten steel to a predetermined extremely low level. First, the molten steel is heated to a specific deoxidation temperature range, which is usually set between 1550°C and 1600°C. Subsequently, silicon-calcium-aluminum alloy is added to the molten steel, which can effectively remove oxygen from the molten steel. At the same time, desulfurizers such as limestone or dolomite are also added to remove sulfur from the molten steel. By precisely controlling the addition amount and reaction time, the oxygen content and sulfur content in the molten steel can be controlled at levels of approximately 0.002% and 0.001%, respectively. This process is critical to the production of high-quality steel, because oxygen and sulfur are harmful impurities in molten steel, and their presence significantly reduces the mechanical properties and corrosion resistance of the steel.

[0037] S2. After completing the deoxidation and desulfurization processes, the next step is to remove the reducing slag on the surface of the molten steel and make dephosphorization slag separately. The components of dephosphorization slag include CaC2, CaF2, and CaO. First, thoroughly remove the reducing slag on the surface of the molten steel, and then prepare the dephosphorization slag according to a specific ratio, which is usually 30% CaC2, 25% CaF2, and 12.5% ​​CaO. After the preparation is completed, the dephosphorization slag is evenly added to the surface of the molten steel. The preparation of dephosphorization slag is completed by precise chemical measurement and mixing technology to ensure the uniformity of its composition and the effectiveness of the reaction.

[0038] S3. In order to ensure that the dephosphorization reaction proceeds smoothly in a reducing atmosphere, it is necessary to maintain a reducing atmosphere above the slag layer. After the dephosphorization slag is formed, a sealed cover is immediately placed above the slag layer, and argon gas is introduced into the cover to drive out the air, maintain a slightly positive pressure in the cover, and prevent air from infiltrating. This step is crucial because it prevents the molten steel from being carbonized when it comes into contact with air at high temperatures, and ensures that the dephosphorization reaction is carried out in an oxygen-free reducing atmosphere. In this way, the oxidation of the molten steel during the production process can be effectively avoided, thereby protecting the purity of the molten steel.

[0039] S4. Dephosphorization reaction is carried out at the slag-steel interface. First, the furnace temperature is adjusted to 1500-1550℃ and kept within this temperature range for a certain period of time to carry out dephosphorization. The CaC2 in the dephosphorization slag will undergo a decomposition reaction, and its chemical equation is:

[0040] (CaC2) = {Ca} + 2[C]

[0041] △G°=63700-34.05T.

[0042] The carbon produced by the decomposition reaction is absorbed by the molten steel, while the calcium participates in the reaction with phosphorus.

[0043] Calcium reacts with phosphorus in the molten steel:

[0044] 3{Ca}+2[p]=[Ca3P2]

[0045] △G°=-284141+134.90T.

[0046] The dephosphorization product Ca3P2 will float up and dissolve into the slag.

[0047] [Ca3P2]=(Ca3P2)

[0048] Dephosphorization is achieved by removing the slag containing Ca3P2 from the furnace. This process is a combination of physical and chemical methods to ensure that the phosphorus content in the molten steel meets the standard, thereby producing steel that meets quality requirements.

[0049] S5. Once the predetermined dephosphorization target is reached, the protective cover is removed, oxygen is blown into the slag layer, and then an appropriate amount of silica sand (SiO2) is added to the slag layer to destroy the Ca3P2 in the slag, followed by slag removal and pouring. The purpose of oxygen blowing is to oxidize the Ca3P2 in the slag and convert it into P2O5 and CaO, thereby preventing Ca3P2 from reacting with water to generate harmful gas PH3. After adding silica sand, Ca3P2 is destroyed and the phosphorus content in the slag is reduced. Subsequently, slag removal and pouring are carried out to obtain pure molten steel. This series of operations ensures the purity and quality of the molten steel, providing a solid foundation for subsequent steel processing and application.

[0050] In this embodiment, by executing the above series of steps, the generation and treatment of the dephosphorization product Ca3P2 can be effectively controlled. In the slag, Ca3P2 will float and dissolve, and then through a carefully designed oxidation treatment, the Ca3P2 in the slag will be converted into P2O5 and CaO, thereby avoiding the risk of Ca3P2 reacting with water to produce harmful gas PH3. The CaC2-CaF2 covered slag dephosphorization process significantly reduces the phosphorus content in the molten steel and improves the quality of the molten steel. Since a reducing atmosphere is maintained above the slag layer, the carbon increase phenomenon of the molten steel during the dephosphorization process is reduced. This process is particularly suitable for the dephosphorization of high-carbon and high-chromium molten steel, and expands the application field of the dephosphorization process.

[0051] The present invention significantly improves the purity and quality of steel. By carrying out dephosphorization reaction within a specific temperature range, phosphorus in molten steel can be removed more efficiently while maintaining the stability of other chemical components of the molten steel. In addition, the present invention not only improves production efficiency and reduces production costs, but also achieves a dual improvement in environmental protection and economic benefits by reducing the emission of harmful gases and improving the quality of molten steel.

[0052] The present invention provides a steel smelting process, which can effectively control the generation and treatment of dephosphorization product Ca3P2, and significantly improve the quality of molten steel. At the same time, the process can also reduce the generation of harmful gases, and achieve a dual improvement in environmental protection and economic benefits. By accurately controlling key parameters in the smelting process, such as temperature, time, and the composition of the covering slag, the present invention ensures the high efficiency of the dephosphorization process and the stability of the molten steel quality, and provides a smelting solution that is both environmentally friendly and economical for the steel industry.

[0053] According to the above description, we have described several preferred embodiments of the present invention in detail. However, the protection scope of the present invention should not be understood to be limited to these specific examples. For those who have relevant knowledge and experience in the technical field, they can make corresponding equivalent substitutions or appropriate modifications based on the technical principles and concepts disclosed in the present invention, and these substitutions or modifications should also be included in the protection scope of the present invention.

[0054] In addition, it should be clear that the above embodiments are only used to illustrate the technical solutions of the present invention and do not constitute any limitation to the present invention. Under the premise of following the basic idea of ​​the present invention, the technical features in the above embodiments can be combined with each other, and the steps can also be performed in different orders according to actual needs. In fact, in addition to the embodiments that have been clearly described, there are many other changes and possibilities in the present invention. In order to maintain the simplicity of the description, these possible changes are not described in detail herein. Although we have elaborated the present invention in detail according to the above embodiments, those skilled in the art should clearly realize that they can still make necessary adjustments to the technical solutions recorded in the above embodiments or make equivalent replacements for some of the technical features therein. These adjustments or replacements will not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions covered by the various embodiments of the present invention.

Claims

1. A steel smelting process, characterized in that: The following steps are involved: S1, deep deoxidation and desulfurization of molten steel, so that the oxygen content and sulfur content in the molten steel reach predetermined values ​​respectively; S2, remove the reducing slag and make dephosphorization slag, the dephosphorization slag is CaC2, CaF2, CaO; S3. Maintain a reducing atmosphere above the slag layer. After the dephosphorization slag is formed into slag, immediately place a sealing cover above the slag layer, introduce argon gas into the cover to drive away the air, maintain a slight positive pressure in the cover to prevent air from infiltrating; S4. Dephosphorization reaction is carried out at the slag-steel interface, the furnace temperature is adjusted to 1500-1550°C, and dephosphorization is carried out at this temperature for a certain period of time; S5. After achieving the desired dephosphorization purpose, remove the protective cover, blow oxygen into the slag layer, then add an appropriate amount of silica sand (SiO2) into the slag layer to destroy Ca3P2 in the slag, and immediately remove the slag for pouring.

2. A steel smelting process according to claim 1, characterized in that: Desulfurization begins when the oxygen content and sulfur content in the S1 molten steel reach about 0.002% and 0.001% respectively.

3. A steel smelting process according to claim 1, characterized in that: The composition of the S2 dephosphorization slag is CaC2 20%-40%, CaF2 20%-30%, and CaO 10%-15%.

4. A steel smelting process according to claim 1, characterized in that: The CaC2 in the dephosphorization slag will undergo a decomposition reaction, and its chemical equation is: (CaC2) = {Ca} + 2[C] △G°=63700-34.05T The carbon produced by the decomposition reaction is absorbed by the molten steel, while the calcium participates in the reaction with phosphorus.

5. The steel smelting process according to claim 1, characterized in that: Calcium reacts with phosphorus in the molten steel: 3{Ca}+2[p]=[Ca3P2] △G°=-284141+134.90T The dephosphorization product Ca3P2 will float up and dissolve into the slag; [Ca3P2]=(Ca3P2) Dephosphorization is achieved by removing the slag containing Ca3P2 from the furnace.

6. A steel smelting process according to claim 1, characterized in that: The chemical equation for the oxidation treatment of the dephosphorized product Ca3P2 is: Ca3P2+4O2=P2O5+3CaO.

7. The steel smelting process according to claim 1, characterized in that: The process also includes oxidizing the slag containing Ca3P2 to prevent Ca3P2 from contacting with water vapor to produce harmful gas PH3.

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