Short-process argon station rapid deep desulfurization process method

Abstract

The invention belongs to the technical field of steelmaking, and particularly relates to a short-process rapid deep desulfurization process method for an argon station. The final temperature of the converter is controlled to be 1650-1700 DEG C; tapping is carried out after converter blowing is finished, by taking the volume of the total molten steel as 100%, when the volume of the tapping molten steel accounts for 25-35% of the volume of the total molten steel, an alloy material containing an aluminum-iron alloy is added into the tapping molten steel, and when the volume of the tapping molten steel accounts for 40-50% of the volume of the total molten steel, lime and a slagging material are added into the tapping molten steel; and after tapping is finished, molten steel is transferred to an argon station, ferro-aluminum and lime are added to the surface of steel ladle slag, and argon blowing stirring is carried out at the bottom of a steel ladle while materials are added. By adopting the method disclosed by the invention, the desulfurization efficiency of the argon station is improved, the rapid deep desulfurization of the argon station is realized, the LF refining time is shortened, the sulfur component is stably controlled within 35ppm, the refining process is simplified, the production cost is reduced, and the method is more suitable for being applied to mass production.

Description

Technical Field

[0001] The present invention belongs to the technical field of steelmaking, and particularly relates to a process method for rapid deep desulfurization in a short-process argon station. Background Art

[0002] The short-process thin-slab continuous casting and rolling production line (CSP) is a production process that combines continuous casting and rolling, aiming to improve production efficiency and reduce costs by reducing intermediate links. This production line usually adopts a compact layout and advanced automation technology, and can complete the whole process from molten steel to finished strip steel in a short time. Due to the thinness of the cast slab in CSP, a funnel-shaped mold is used, and the submerged nozzle is small, so the nozzle is prone to nodulation during the casting process. In addition, due to the high continuous casting speed and large cooling intensity of the cast slab, the cast slab is prone to cracks. The continuous casting process has strict control requirements for the purity of molten steel and the sulfur content of crack-sensitive elements. Therefore, the production path of "converter - argon station - casting machine" is not applicable to the short-process production line. To meet the above composition and molten steel purity control requirements, the production of general carbon steel in the short-process production line generally requires LF slag-making deep desulfurization and calcium treatment.

[0003] Due to the high requirements for the quality of molten steel in the thin-slab continuous casting process, sufficient LF refining treatment time (50 - 70 min / furnace) must be ensured when designing the general carbon steel process for all current short-process production lines. The process path for short-process general carbon steel production is as follows: 1. Electric furnace smelting: Scrap steel and alloy materials are added to the electric furnace and melted by arc heating to preliminarily adjust the composition of the molten steel (such as carbon, silicon, manganese, etc.); 2. LF furnace refining: Slag-making deep desulfurization: A high-alkalinity slag is formed by adding slag-making agents (such as lime, fluorite, etc.) to adsorb sulfur in the molten steel; Calcium treatment: Calcium wire or calcium alloy is added to further desulfurize and improve the morphology of inclusions; Composition fine-tuning: The composition of the molten steel is precisely adjusted to meet the requirements of general carbon steel; 3. Argon station treatment: The molten steel is stirred by blowing argon to promote the floating of inclusions and the homogenization of composition; 4. Continuous casting: The refined molten steel is cast into steel billets, which results in the steelmaking cost being more than 40 yuan / ton higher than that of the conventional process, mainly reflected in three aspects: increased LF energy consumption, increased consumption of auxiliary materials, and reduced alloy yield. Theoretically analyzed, the two links of converter tapping and argon blowing station have excellent thermodynamic and kinetic conditions, and it is completely possible to transfer some refining functions of the LF furnace (including slag-making desulfurization, inclusion removal, and composition adjustment, etc.) to the converter and argon station. The LF furnace only performs operations such as temperature compensation and composition fine-tuning. In this way, the LF refining cycle can be greatly compressed, the LF heating time can be reduced, and thus the process costs in the above three aspects can be significantly reduced.

[0004] The prior art "A smelting method for improving the desulfurization efficiency of a converter" proposes that when the converter blowing reaches the end point and meets the tapping conditions, add Al particles, a strong deoxidizer, into the converter. Before tapping from the converter, pre-add the liquid refining slag in the ladle after the continuous casting of the previous heat to the ladle. After tapping, move the ladle to the argon station and first feed metal Ca wire for strong deoxidation, add aluminum particles to the slag surface for deoxidation, and at the same time cooperate with continuous bottom blowing of argon for strong stirring to achieve the purpose of rapid slag formation and desulfurization. Although this method can desulfurize quickly, deep deoxidation in the converter furnace body is likely to cause the return of P in the converter slag, resulting in uncontrolled P content; the liquid refining slag needs to be transported from the caster to the converter, affecting the production logistics rhythm; the low temperature of the liquid refining slag is likely to block the argon blowing holes at the bottom of the large ladle, causing poor argon blowing in the subsequent large ladle, and a large amount of smoke and dust will be generated during the tapping process, making it impossible to judge the steel flow and prone to slag entrainment during tapping; feeding metal Ca wire for strong deoxidation in the argon station increases the cost. In summary, this method is difficult in actual large-scale production, is not conducive to production and quality stability, and will increase the production cost at the same time.

[0005] The prior art "A method for rapid desulfurization of converter-direct aluminum-killed steel" proposes that before tapping from the converter, pre-add the remaining slag after the LF refining process casting to the ladle. After the tapping is completed, add aluminum powder to the steel liquid surface for deoxidation and slag formation to achieve the purpose of rapid slag formation and desulfurization. This method pre-adds the remaining slag after the LF refining process casting to the ladle before tapping from the converter. The cast residue needs to be transported from the caster to the converter, affecting the production logistics rhythm; the low temperature of the liquid refining slag is likely to block the argon blowing holes at the bottom of the large ladle, causing poor argon blowing in the subsequent large ladle, and a large amount of smoke and dust will be generated during the tapping process, making it impossible to judge the steel flow and prone to slag entrainment during tapping, which is difficult in large-scale production applications; at the same time, the final sulfur content of this method is 0.009 - 0.014%, and the desulfurization efficiency is low, not meeting the production and quality requirements of the short-process production line with a sulfur content ≤ 0.005%.

[0006] The prior art "A method for shortening the smelting time of low-carbon aluminum-killed steel in the LF furnace" proposes mainly to perform strong stirring with bottom blowing of argon in the ladle during tapping from the converter, perform "top blowing + bottom blowing" strong stirring in the argon blowing station, and perform a process of strong stirring to break the slag layer - medium stirring for heating - strong stirring for slag formation in the LF furnace. In the application cases of this process method, the sulfur content at the converter tapping is 0.024%, 0.026%, and 0.028% respectively, and the final sulfur content at the argon station is 0.022%, 0.020%, and 0.027% respectively. It can be seen that this method has almost no desulfurization ability at the argon station, and deep desulfurization treatment is required in the LF furnace, resulting in low production efficiency.

[0007] The prior art "A Method for Rapid Desulfurization in Steelmaking" proposes that before tapping the refined molten steel, a quarter to a half of the hot refined slag from the previous furnace's casting residue is poured into the ladle ready for tapping, and 3 - 7 kg of lime per ton of molten steel is added to the ladle filled with the molten steel to be refined during tapping. In this method, the casting residue needs to be transported from the caster to the converter, which affects the production logistics rhythm; the temperature of the liquid refined slag is relatively low, which is likely to block the argon blowing holes at the bottom of the large ladle, resulting in poor argon blowing in the subsequent large ladle. A large amount of dust is generated during the tapping process, making it impossible to judge the molten steel flow, and it is easy to have slag entrainment during tapping, which is difficult to apply in large-scale production. At the same time, the final sulfur content of this method in the argon station is 0.015%, and the desulfurization efficiency is relatively low. Summary of the Invention

[0008] The object of the present invention is to address the deficiencies in the prior art, such as low desulfurization efficiency in the argon station, great difficulty in the production process, and being unfavorable for large-scale production. Therefore, a short-process argon station rapid deep desulfurization process method is proposed. The process method of the present invention makes full use of the excellent thermodynamic and kinetic conditions during the tapping of the converter. Strong deoxidation and rapid slag formation are carried out in the early stage of converter tapping, rapid slag formation and deep desulfurization are carried out in the argon station, and the LF furnace only slightly adjusts the temperature and composition, and soft argon blowing and calcium treatment are used to remove inclusions in the steel. This process method reduces the refining time of the LF furnace, solves the problem of rapid deep desulfurization in large-scale production, improves production efficiency, realizes smooth production, and reduces costs.

[0009] The present invention proposes a short-process argon station rapid deep desulfurization process method, which includes the following steps: Step S1, controlling the converter end temperature: restricting the end temperature, and requiring the end temperature to be controlled at 1650 - 1700 °C; Step S2, after the converter blowing is completed, tapping is carried out. Taking the total volume of molten steel as 100%, when the volume of the molten steel during tapping is 25 - 35% of the total volume of the molten steel, an alloy material containing ferroaluminum alloy is added to the molten steel during tapping. When the volume of the molten steel during tapping is 40 - 50% of the total volume of the molten steel, lime and slag melting materials are added to the molten steel during tapping; Step S3, after tapping is completed, the molten steel is transferred to the argon station, ferroaluminum and lime are added to the surface of the ladle slag, and while adding the materials, argon blowing and stirring are carried out at the bottom of the ladle.

[0010] Preferably, in Step S1, the end temperature is 1695 - 1700 °C.

[0011] Preferably, in Step S2, after the converter blowing is completed, tapping is carried out, and the sulfur element content in the molten steel before tapping is 0.015 - 0.040%.

[0012] Preferably, in step S2, based on the total volume of molten steel being 100%, when the volume of the tapped molten steel is 33.3% of the total volume of molten steel, an alloy material containing ferroaluminum alloy is added to the tapped molten steel. When the volume of the tapped molten steel is 50% of the total volume of molten steel, lime and slag-making materials are added to the tapped molten steel. More preferably, in step S2, when the composition and content of the tapped molten steel are: C: 0.04 - 0.1%, Mn: 0.08 - 0.15%, P: 0.15 - 0.30%, S: 0.015 - 0.055%, and the rest are Fe elements and trace elements, an alloy material containing ferroaluminum alloy is added to the tapped molten steel.

[0013] Preferably, in step S2, the dosage ratio of ferroaluminum alloy to tapped molten steel is 2.1 - 3.3 kg / t, the dosage ratio of lime to tapped molten steel is 3.0 - 4.9 kg / t, and the dosage ratio of slag-making materials to tapped molten steel is 0.6 - 1.5 kg / t; the aluminum element content in the ferroaluminum alloy is 60 - 65%; the composition and content of the slag-making materials are: CaO: 28 - 38%, Al 2 O 3 : 38 - 48%, SiO 2 : ≤10%, MgO: ≤5%, and the balance is Fe.

[0014] More preferably, in step S2, the dosage ratio of ferroaluminum alloy to tapped molten steel is 2.42 kg / t, the dosage ratio of lime to tapped molten steel is 3.64 kg / t, and the dosage ratio of slag-making materials to tapped molten steel is 0.91 kg / t.

[0015] Preferably, in step S3, the dosage ratio of ferroaluminum to ladle slag is 0.3 - 1.2 kg / t, and the dosage ratio of lime to ladle slag is 1.1 - 2.7 kg / t.

[0016] More preferably, in step S3, the dosage ratio of ferroaluminum to ladle slag is 0.42 kg / t, and the dosage ratio of lime to ladle slag is 2.42 kg / t.

[0017] Preferably, in step S3, argon stirring is carried out at the bottom of the ladle, the argon stirring time is 5 - 10 min, and the argon flow rate is controlled at 800 - 1000 NL / min.

[0018] Preferably, this process method further includes: after the argon stirring at the bottom of the ladle is completed, transporting the molten steel to the LF furnace, and adding lime and steel-aluminum pellets to the surface of the ladle slag respectively to make the sulfur element content in the ladle slag ≤50 ppm, wherein the dosage ratio of lime to ladle slag is 0.85 - 3.03 kg / t, the dosage ratio of steel-aluminum pellets to ladle slag is 0.1 - 1.0 kg / t; the aluminum element content in the steel-aluminum pellets is ≥99.5%.

[0019] More preferably, the process method further includes: after the sulfur content in the ladle slag is ≤ 50 ppm, soft blowing argon and calcium treatment operations are performed on the molten steel. Among them, the soft blowing argon gas flow rate is controlled at 50 - 200 NL / min, and the argon bubble diameter is ≤ 300 mm; the soft blowing argon time before calcium treatment is 3 - 8 min, and the soft blowing argon time after calcium treatment is 3 - 5 min.

[0020] In a short - process argon station rapid deep desulfurization process method according to the present invention, at least the following

[0021] Beneficial effects:

[0022] (1) In the present invention, by making full use of excellent thermodynamic conditions (controlling the end - point temperature at 1650 - 1700 °C) and kinetic conditions during converter tapping: when the volume of the tapped molten steel is 25 - 35% of the total molten steel volume, an alloy material containing aluminum - iron alloy is added to the tapped molten steel. At this time, the kinetic conditions of the molten steel are favorable for the rapid chemical reaction between aluminum - iron and oxygen in the steel, so oxygen in the steel can be rapidly removed, and the free oxygen in the steel is stably controlled within a very low range; when the volume of the tapped molten steel is 40 - 50% of the total molten steel volume, lime and slag - melting materials are added to the tapped molten steel. At this time, the kinetic conditions of the molten steel are favorable for the rapid melting of lime and slag - melting materials, forming a slag with a certain alkalinity and reducibility, so slag formation can be rapid, creating favorable conditions for desulfurization in the argon station; rapid slag formation and deep desulfurization are carried out in the argon station, oxygen in the slag is rapidly removed, lime is added according to the slag color to form a reducing slag with a higher alkalinity, and large - argon stirring is combined to form favorable conditions for desulfurization and rapid deep desulfurization. After deep desulfurization in the argon station, the molten steel is transported to the LF furnace, where the temperature and composition of the molten steel are precisely controlled. After the temperature, composition, and final slag adjustment operations are completed, soft blowing argon and calcium treatment operations are performed on the molten steel. Through the process method of the present invention, the sulfur content in the steel finished product after refining is below 35 ppm, and the refining cycle of the LF furnace is shortened to 20 - 40 min;

[0023] (2) The process method of the present invention simplifies the refining process, reduces production costs, is more suitable for application in large - scale production, improves production efficiency, and realizes smooth production. Specific embodiments

[0024] The following details the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only for explaining and illustrating the present invention, and are not used to limit the present invention.

[0025] The present invention provides a short-process argon station rapid deep desulfurization process method, which includes the following steps: Step S1, controlling the converter end temperature: restricting the end temperature, and requiring the end temperature to be controlled at 1650 - 1700 °C; Step S2, tapping the steel after the converter blowing is completed. Taking the volume of the total molten steel as 100%, when the volume of the tapped molten steel is 25 - 35% of the volume of the total molten steel, adding an alloy material containing ferrosilicon aluminum to the tapped molten steel, and when the volume of the tapped molten steel is 40 - 50% of the volume of the total molten steel, adding lime and slag melting materials to the tapped molten steel; Step S3, after tapping is completed, the molten steel is transferred to the argon station, adding ferrosilicon aluminum and lime on the surface of the ladle slag, and while adding the materials, blowing argon and stirring at the bottom of the ladle.

[0026] In the specific implementation manner of the process method of the present invention, the purpose of controlling the end temperature at 1650 - 1700 °C is to provide better thermodynamic conditions for rapid slag formation. When the temperature is lower than 1650 °C, it is not conducive to the melting of the slag materials, affecting the slag formation speed and desulfurization rate. When the temperature is higher than 1700 °C, although it is beneficial to slag formation and desulfurization, it will cause a certain waste of temperature, and the temperature at the end of refining will be too high, which is not conducive to the stable casting of the continuous casting machine. For example, the end temperature can be controlled at 1650 °C, 1675 °C, 1689 °C, 1694 °C, 1698 °C or 1700 °C.

[0027] The reason why the present invention adds an alloy material containing ferrosilicon aluminum (ferrosilicon aluminum, ferrosilicon, ferromanganese or silicomanganese alloy, wherein the addition amounts of ferrosilicon, ferromanganese or silicomanganese alloy are determined according to the specific steel grades produced, and the addition amounts for different steel grades are different) when the volume of the tapped molten steel is 25 - 35% of the volume of the total molten steel; and adds lime and slag melting materials through a high-position bin to rapidly form slag when the volume of the tapped molten steel is 40 - 50% of the volume of the total molten steel is to make full use of the excellent thermodynamic and kinetic conditions and the strong stirring effect on the molten steel during the converter tapping process, adding deoxidizing materials in the early stage of tapping to rapidly remove oxygen in the steel and stably control the free oxygen in the steel within an extremely low range, and proportioning lime and slag melting materials, which is more conducive to rapid slag formation and creates favorable conditions for desulfurization in the argon station.

[0028] In a preferred embodiment of the process method of the present invention, tapping is carried out after the converter blowing is completed. Taking the volume of the total molten steel as 100%, when the volume of the tapped molten steel is 33.3% of the volume of the total molten steel, an alloy material containing ferrotitanium is added to the tapped molten steel. When the volume of the tapped molten steel is 50% of the volume of the total molten steel, lime and slag melting materials are added to the tapped molten steel. In a more preferred case, in step S2, when the composition and content of the tapped molten steel are: C: 0.04 - 0.1%, Mn: 0.08 - 0.15%, P: 0.15 - 0.30%, S: 0.015 - 0.055%, and the rest are Fe element and trace elements, an alloy material containing ferrotitanium is added to the tapped molten steel.

[0029] In a specific embodiment of the process method of the present invention, in step S2, the argon flow rate during converter tapping is 200 - 500 L / min, for example, it can be 200 L / min, 300 L / min, 330 L / min, 380 L / min, 420 L / min or 500 L / min.

[0030] In a specific embodiment of the process method of the present invention, in step S2, tapping is carried out after the converter blowing is completed. Before tapping, the sulfur element content in the molten steel is 0.015 - 0.040%, for example, it can be 0.015%, 0.016%, 0.025%, 0.031%, 0.035% or 0.040%; the end point oxygen content is 500 - 800 ppm, for example, it can be 500 ppm, 511 ppm, 546 ppm, 672 ppm, 787 ppm or 800 ppm.

[0031] In the specific embodiment of the process method of the present invention, in step S2, the dosage ratio of ferroaluminum to the molten steel tapped is 2.1 - 3.3 kg / t. For example, it can be 2.1 kg / t, 2.12 kg / t, 2.42 kg / t, 3.03 kg / t or 3.3 kg / t. When the dosage ratio of ferroaluminum to the molten steel tapped is less than 2.1 kg / t, it is likely to cause low deoxidation intensity, which is not conducive to the formation of a reducing slag. When the dosage ratio of ferroaluminum to the molten steel tapped is greater than 3.3 kg / t, it will cause cost waste and is likely to cause the Al content to exceed the product standard range, which is not conducive to the control of the composition of the molten steel tapped. The dosage ratio of lime to the molten steel tapped is 3.0 - 4.9 kg / t. For example, it can be 3.0 kg / t, 3.1 kg / t, 3.64 kg / t, 4.85 kg / t or 4.9 kg / t. When the dosage ratio of lime to the molten steel tapped is less than 3.0 kg / t, the alkalinity is too low, which is not conducive to the desulfurization condition. When the dosage ratio of lime to the molten steel tapped is greater than 4.9 kg / t, the slag will be sticky and have poor fluidity, which is not conducive to the desulfurization reaction at the interface between the steel and the slag. The dosage ratio of slag melting material to the molten steel tapped is 0.6 - 1.5 kg / t. For example, it can be 0.6 kg / t, 0.91 kg / t, 1.14 kg / t, 1.21 kg / t or 1.5 kg / t. When the dosage ratio of slag melting material to the molten steel tapped is less than 0.6 kg / t, it is not conducive to the rapid melting of lime. When the dosage ratio of slag melting material to the molten steel tapped is greater than 1.5 kg / t, the alkalinity will be low, and more lime needs to be added to increase the alkalinity, resulting in cost waste.

[0032] In the specific embodiment of the process method of the present invention, the content of aluminum element in ferroaluminum is 60 - 65%; the composition and content of the slag melting material are: CaO: 28 - 38%, Al 2 O 3 : 38 - 48%, SiO 2 : ≤10%, MgO: ≤5%, and the balance is Fe. The melting temperature of the slag melting material is 1350 - 1450°C; the function of the slag melting material is to assist the melting of lime and form a CaO - Al 2 O 3 -SiO 2 low - melting - point slag system.

[0033] In the preferred embodiment of the process method of the present invention, in step S2, the dosage ratio of ferroaluminum to the molten steel tapped is 2.42 kg / t, the dosage ratio of lime to the molten steel tapped is 3.64 kg / t, and the dosage ratio of slag melting material to the molten steel tapped is 0.91 kg / t. By reasonably controlling the addition timing and addition amount of each material, the sulfur content in the finished steel product after refining can be below 30 ppm, and at the same time, the refining cycle of the LF furnace is shortened to below 25 min.

[0034] In the specific implementation of the process method of the present invention, in step S3, the dosage ratio of ferrosilicon to ladle slag is 0.3 - 1.2 kg / t. For example, it can be 0.3 kg / t, 0.42 kg / t, 0.61 kg / t, 0.88 kg / t, 0.91 kg / t or 1.2 kg / t. When the dosage ratio of ferrosilicon to ladle slag is less than 0.3 kg / t, deoxidation will be insufficient, which is not conducive to rapid desulfurization. When the dosage ratio of ferrosilicon to ladle slag is greater than 1.2 kg / t, the added amount will be excessive, which is not conducive to cost reduction; the dosage ratio of lime to ladle slag is 1.1 - 2.7 kg / t. For example, it can be 1.1 kg / t, 2.41 kg / t, 2.42 kg / t or 2.7 kg / t.

[0035] In the preferred implementation of the process method of the present invention, in step S3, the dosage ratio of ferrosilicon to ladle slag is 0.42 kg / t, and the dosage ratio of lime to ladle slag is 2.42 kg / t. After transporting the ladle to the argon station, appropriate amounts of ferrosilicon and lime are added to the ladle slag. After the treatment at the argon station is completed, sampling and chemical analysis are taken, and it can be measured that the sulfur content in the sample is about 35 ppm.

[0036] In the specific implementation of the process method of the present invention, in step S3, argon stirring is carried out at the bottom of the ladle. The argon stirring time is 5 - 10 min, and the argon gas flow rate is controlled at 800 - 1000 NL / min.

[0037] The reason why the present invention adds 0.3 - 1.2 kg / t of ferrosilicon on the surface of the ladle slag at the argon station, supplements 1.1 - 2.7 kg / t of lime, controls the strong stirring time to be 5 - 10 min, and controls the bottom blowing gas flow rate at 800 - 1000 NL / min during the strong stirring process is to quickly remove oxygen from the slag, supplement lime according to the slag color to form a reducing slag with a higher alkalinity, cooperate with large argon stirring to form favorable conditions for desulfurization, and quickly and deeply desulfurize.

[0038] In the specific implementation of the process method of the present invention, the process method further includes: compensating the temperature according to the arrival temperature and the casting temperature of the steel grade. The compensated temperature is controlled to increase by 10 - 25 °C according to the target end temperature. For example: taking Q235B(L) as an example, the arrival temperature is 1560 °C, and the casting temperature requirement of the steel grade is 1568 °C. Then the compensated temperature is controlled according to 1583 - 1593 °C, and the off-station temperature can be the same as the casting temperature; and precisely controlling the molten steel composition according to the final composition at the argon station, that is, sampling and chemical analyzing the composition according to the final composition at the argon station, and adding alloys such as aluminum, manganese, and silicon according to the composition standard range of the steel grade to make it meet the composition standard range.

[0039] In the specific implementation of the process method of the present invention, the process method further includes: after the argon blowing and stirring at the bottom of the ladle are completed, transporting the molten steel to the LF furnace, and adding lime and steel-aluminum pellets to the surface of the ladle slag respectively according to the slag color to further adjust the slag and desulfurize, so that the sulfur element content in the ladle slag ≤ 50 ppm. Specifically, the oxidizing property of the slag is judged by the slag color. The black slag represents a higher oxygen content in the slag, with strong oxidizing property, and further deoxidation is required; the slag showing green transparency represents a lower slag oxidizing property and a lower alkalinity, and lime needs to be added to increase the alkalinity to provide favorable conditions for continuous desulfurization; the slag color being white and ceramic-like represents a higher slag reducibility and a higher alkalinity, which is beneficial to desulfurization. Among them, the dosage ratio of lime to ladle slag is 0.85 - 3.03 kg / t, for example, it can be 0.85 kg / t, 0.9 kg / t, 0.91 kg / t, 2.76 kg / t, 2.96 kg / t or 3.03 kg / t. When the dosage ratio of lime to ladle slag is less than 0.85 kg / t, the alkalinity is too low, which is not conducive to rapid desulfurization. When the dosage ratio of lime to ladle slag is greater than 3.03 kg / t, the slag alkalinity is too high, the fluidity is poor, and the desulfurization rate is low; the dosage ratio of steel-aluminum pellets to ladle slag is 0.1 - 1.0 kg / t, for example, it can be 0.1 kg / t, 0.12 kg / t, 0.15 kg / t, 0.45 kg / t, 0.76 kg / t or 1.0 kg / t. When the dosage ratio of steel-aluminum pellets to ladle slag is less than 0.1 kg / t, the reducibility of the molten steel is poor, which is not conducive to desulfurization. When the dosage ratio of steel-aluminum pellets to ladle slag is greater than 1.0 kg / t, the Al content is too high, which is not conducive to cost control; the aluminum element content in the steel-aluminum pellets ≥ 99.5%.

[0040] The reason why the present invention compensates the temperature according to the arrival temperature and the casting temperature of the steel grade, adds alloys such as ferrosilicon, ferromanganese, and aluminum pellets to fine-tune the molten steel composition according to the final composition at the argon station, and at the same time adds 0.85 - 3.03 kg / t of lime and 0.1 - 1.0 kg / t of steel-aluminum pellets to the slag surface according to the slag color to further adjust the slag and desulfurize is that there are certain fluctuations in the temperature and sulfur content at the argon station, and the LF furnace is finely adjusted to make the final molten steel temperature and composition meet the standard requirements.

[0041] In the specific implementation of the process method of the present invention, the process method further includes: after the sulfur element content in the ladle slag ≤ 50 ppm, soft argon blowing and calcium treatment operations are carried out on the molten steel. Among them, the soft argon blowing gas flow rate is controlled at 50 - 200 NL / min, and the argon flower diameter ≤ 300 mm; the soft argon blowing time before calcium treatment is 3 - 8 min, and the soft argon blowing time after calcium treatment is 3 - 5 min, which is an effective measure to improve the purity of molten steel and can improve the castability of the short-process thin slab caster; the calcium treatment is carried out by feeding a metal calcium wire through a wire feeder, generally feeding it into the molten steel at a speed of 4 m / s to carry out a denaturing treatment on the Al 2 O 3 inclusions in the molten steel to form low-melting-point Al7 Ca 12 , which is beneficial to the purity of molten steel and controls the surface quality of the product.

[0042] Unless otherwise specified, the test methods or testing methods described in the following examples are all conventional methods; the reagents and materials, unless otherwise specified, are all obtained from conventional commercial channels or prepared by conventional methods.

[0043] Example 1

[0044] This example was carried out in a 150-ton converter, smelting the Q235B steel grade, heat E310938. The smelting process route was: hot metal pretreatment - converter smelting - argon station - LF treatment - continuous casting. This process method includes the following steps:

[0045] Step S1: After the converter blowing is completed, the temperature is measured. The end point temperature is 1698 °C, the end point oxygen content is 546 ppm, and the sulfur content in the molten steel tapped is 0.016%;

[0046] Step S2: After the converter blowing is completed, tapping is carried out. The argon flow rate during tapping from the converter is 300 L / min. Based on the total volume of molten steel being 100%, when the volume of the molten steel tapped is one-third of the total volume of molten steel, ferrosilicon aluminum, carburizer, ferrosilicon, and silicomanganese alloy are added to the molten steel tapped. Among them, the dosage ratio of ferrosilicon aluminum alloy (the aluminum element content is 63%) to the molten steel tapped is 2.42 kg / t, 1.21 kg / t of carburizer is added, 0.61 kg / t of ferrosilicon is added, and 1.82 kg / t of silicomanganese alloy is added. When the volume of the molten steel tapped is one-half of the total volume of molten steel, lime and slag melting materials (the composition and content of the slag melting materials are: CaO: 35.7%, Al 2 O 3 : 42.2%, SiO 2 : 7.4%, MgO: 4.1%, Fe: 10.6%) are added through a high-position bin. Among them, the dosage ratio of lime to the molten steel tapped is 3.64 kg / t, and the dosage ratio of the slag melting materials to the molten steel tapped is 0.91 kg / t;

[0047] Step S3: After tapping is completed, the molten steel is transferred to the argon station. Ferrosilicon aluminum is added to remove the oxygen in the slag on the surface of the ladle slag. The dosage ratio of ferrosilicon aluminum to the ladle slag is 0.42 kg / t. Lime is supplemented according to the slag condition. The dosage ratio of lime to the ladle slag is 2.42 kg / t. While adding the materials, argon stirring is carried out at the bottom of the ladle. The stirring time is 10 min, and the argon flow rate is 850 NL / min. After the treatment at the argon station is completed, sampling and analysis are taken. The sulfur element content is 0.0035%;

[0048] Step S4: The molten steel is transported to the LF furnace. The arrival temperature at the LF furnace is 1588°C, which is controlled 23°C higher than the target end temperature without heating compensation. Lime and steel-aluminum pellets (the aluminum element content in the steel-aluminum pellets is 99.8%) are added to the slag surface according to the slag color to adjust the ladle slag. Among them, the dosage ratio of lime to ladle slag is 0.9 kg / t, and the dosage ratio of steel-aluminum pellets to ladle slag is 0.15 kg / t.

[0049] Step S5: After the ladle slag adjustment is completed, soft argon blowing and calcium treatment operations are carried out. The soft argon blowing flow rate is controlled at 80 NL / min, the argon flower diameter is 120 mm, the soft argon blowing time before calcium treatment is 4.6 min, and the soft argon blowing time after calcium treatment is 3.5 min.

[0050] In Example 1, a steel sample is taken at the end of the argon station for composition analysis, and [sulfur] is 0.0035%; a steel sample is taken at the end of refining for composition analysis, and [sulfur] is 0.0026%; the refining cycle of the LF furnace is 24 min.

[0051] Example 2

[0052] This implementation case is carried out in a 150-ton converter for smelting the Q235B steel grade, furnace number E310942. The smelting process route is: hot metal pretreatment - converter smelting - argon station - LF treatment - continuous casting. This process method includes the following steps:

[0053] Step S1: After the converter blowing is completed, temperature measurement is carried out. The end temperature is 1675°C, the end oxygen content is 511 ppm, and the sulfur content in the tapped steel is 0.025%.

[0054] Step S2: After the converter blowing is completed, tapping is carried out. The argon flow rate during tapping from the converter is 330 L / min. Calculated based on the total volume of molten steel being 100%, when the volume of the tapped molten steel is one-third of the total volume of molten steel, ferrotitanium, carburizer, ferrosilicon, and silicomanganese alloy are added to the tapped molten steel. Among them, the dosage ratio of ferrotitanium alloy (the aluminum element content is 63.7%) to the tapped molten steel is 2.12 kg / t. When the volume of the tapped molten steel is one-half of the total volume of molten steel, lime and slag melting materials (the composition and content of the slag melting materials are: CaO: 37.3%, Al 2 O 3 : 42.6%, SiO 2 : 8.4%, MgO: 2.9%, Fe: 8.8%) are added through the high-level bunker. Among them, the dosage ratio of lime to the tapped molten steel is 3.1 kg / t, and the dosage ratio of the slag melting materials to the tapped molten steel is 1.14 kg / t.

[0055] Step S3: After the tapping is completed, the molten steel is transferred to the argon station. Ferro-aluminum is added to the surface of the ladle slag to remove the dissolved oxygen in the slag. The dosage ratio of ferro-aluminum to the ladle slag is 0.88 kg / t. Lime is added as a supplement according to the slag condition, and the dosage ratio of lime to the ladle slag is 2.7 kg / t. While adding the materials, argon stirring is carried out at the bottom of the ladle. The stirring time is 9 min, and the argon flow rate is 970 NL / min. After the treatment at the argon station, samples are taken for analysis, and the sulfur content is 0.0044%.

[0056] Step S4: The molten steel is transported to the LF furnace. The temperature of the molten steel arriving at the LF furnace is 1583 °C, which is 18 °C higher than the target end temperature, and no heating compensation is carried out. According to the color of the molten slag, lime and steel-aluminum pellets (the aluminum content in the steel-aluminum pellets is 99.7%) are added to the slag surface to adjust the ladle slag. Among them, the dosage ratio of lime to the ladle slag is 0.91 kg / t, and the dosage ratio of steel-aluminum pellets to the ladle slag is 0.12 kg / t.

[0057] Step S5: After the ladle slag is adjusted, soft argon blowing and calcium treatment operations are carried out. The soft argon blowing flow rate is controlled at 170 NL / min, the argon flower diameter is 240 mm, the soft argon blowing time before calcium treatment is 5.1 min, and the soft argon blowing time after calcium treatment is 3.7 min.

[0058] In Example 2, a steel sample is taken at the end of the argon station for composition analysis, and [S] is 0.0044%; a steel sample is taken at the end of refining for composition analysis, and [S] is 0.0032%; the refining cycle of the LF furnace is 25 min.

[0059] Example 3

[0060] This example is carried out in a 150-ton converter for smelting the steel grade DC01, heat number E311464. The smelting process route is: hot metal pretreatment - converter smelting - argon station - LF treatment - continuous casting. This process method includes the following steps:

[0061] Step S1: After the converter blowing is completed, the temperature is measured. The end temperature is 1689 °C, the end oxygen content is 672 ppm, and the tapping sulfur content is 0.031%.

[0062] Step S2: After the converter blowing is completed, tapping is carried out. The argon flow rate during tapping from the converter is 420 L / min. Based on the total volume of the molten steel being 100%, when the volume of the molten steel during tapping is one-third of the total volume of the molten steel, ferro-aluminum and ferromanganese alloys are added to the molten steel during tapping. Among them, the dosage ratio of the ferro-aluminum alloy (the aluminum content is 64.3%) to the molten steel during tapping is 3.03 kg / t. When the volume of the molten steel during tapping is one-half of the total volume of the molten steel, lime and slag melting materials (the composition and content of the slag melting materials are: CaO: 36.4%, Al 2 O 3 : 43.3%, SiO 2: 9.2%, MgO: 3.7%, Fe: 7.4%). Among them, the dosage ratio of lime to the molten steel tapped from the converter is 3.64 kg / t, and the dosage ratio of slag-making materials to the molten steel tapped from the converter is 1.21 kg / t;

[0063] Step S3: After the tapping is completed, the molten steel is transferred to the argon station. Aluminum iron is added to the surface of the ladle slag to remove the dissolved oxygen in the slag. The dosage ratio of aluminum iron to the ladle slag is 0.91 kg / t. Lime is added as needed according to the slag condition. The dosage ratio of lime to the ladle slag is 2.41 kg / t. While adding the materials, argon blowing and stirring are carried out at the bottom of the ladle. The stirring time is 8 min, and the argon blowing flow rate is 870 NL / min. After the treatment at the argon station is completed, sampling and chemical analysis are taken. The sulfur element content is 0.0050%;

[0064] Step S4: The molten steel is transported to the LF furnace. The arrival temperature of the LF furnace is 1607 °C, and the temperature is compensated by heating for 2 min; Lime and steel-aluminum pellets (the aluminum element content in the steel-aluminum pellets is 99.7%) are added to the slag surface according to the color of the molten slag to adjust the ladle slag. Among them, the dosage ratio of lime to the ladle slag is 2.76 kg / t, and the dosage ratio of steel-aluminum pellets to the ladle slag is 0.45 kg / t;

[0065] Step S5: After the ladle slag adjustment is completed, soft argon blowing and calcium treatment operations are carried out. The soft argon blowing flow rate is controlled at 70 NL / min, the argon bubble diameter is 140 mm, the soft argon blowing time before calcium treatment is 8 min, and the soft argon blowing time after calcium treatment is 5 min.

[0066] In Example 3, a steel sample is taken at the end of the argon station for composition analysis, and [sulfur] is 0.0050%; a steel sample is taken at the end of refining for composition analysis, and [sulfur] is 0.0030%; the refining cycle of the LF furnace is 38 min.

[0067] Example 4

[0068] This implementation case is carried out in a 150-ton converter for smelting the DC01 steel grade, heat E411643. The smelting process route is: hot metal pretreatment - converter smelting - argon station - LF treatment - continuous casting. This process method includes the following steps:

[0069] Step S1: After the converter blowing is completed, temperature measurement is carried out. The end point temperature is 1694 °C, the end point oxygen content is 787 ppm, and the sulfur content in the tapped steel is 0.035%;

[0070] Step S2: After the converter blowing is completed, tapping is carried out. The argon flow rate during tapping from the converter is 380 L / min. Calculated based on the total molten steel volume being 100%, when the volume of the molten steel during tapping is one-third of the total molten steel volume, ferro-aluminum and ferromanganese alloys are added to the molten steel during tapping. Among them, the dosage ratio of ferro-aluminum alloy (with an aluminum element content of 63.8%) to the molten steel during tapping is 3.03 kg / t. When the volume of the molten steel during tapping is one-half of the total molten steel volume, lime and slag melting materials (the composition and content of the slag melting materials are: CaO: 37.4%, Al 2 O 3 : 42.3%, SiO 2 : 8.2%, MgO: 4.7%, Fe: 7.4%) are added through a high-level bunker. Among them, the dosage ratio of lime to the molten steel during tapping is 4.85 kg / t, and the dosage ratio of the slag melting materials to the molten steel during tapping is 1.5 kg / t;

[0071] Step S3: After tapping is completed, the molten steel is transferred to the argon station. Ferro-aluminum is added to remove the oxygen in the slag on the surface of the ladle slag, and the dosage ratio of ferro-aluminum to the ladle slag is 0.61 kg / t. Since the oxygen content at the converter end > 700 ppm, additional ferro-aluminum is added to the surface of the ladle slag, and the dosage ratio of the additional ferro-aluminum to the ladle slag is 0.61 kg / t; Lime is added according to the slag condition, and the dosage ratio of lime to the ladle slag is 2.42 kg / t. While adding the materials, argon stirring is carried out at the bottom of the ladle, the stirring time is 10 min, and the argon flow rate is 1000 NL / min. After the treatment at the argon station is completed, sampling and chemical analysis are taken, and the sulfur element content is 0.007%;

[0072] Step S4: The molten steel is transported to the LF furnace. The arrival temperature at the LF furnace is 1605 °C, and the temperature is compensated by heating for 2 min; According to the color of the molten slag, lime and steel-aluminum pellets (with an aluminum element content of 99.8% in the steel-aluminum pellets) are added to the slag surface to adjust the ladle slag. Among them, the dosage ratio of lime to the ladle slag is 2.96 kg / t, and the dosage ratio of the steel-aluminum pellets to the ladle slag is 0.76 kg / t;

[0073] Step S5: After the ladle slag adjustment is completed, soft argon blowing and calcium treatment operations are carried out. The soft argon blowing flow rate is controlled at 140 NL / min, the argon flower diameter is 210 mm, the soft argon blowing time before calcium treatment is 6 min, and the soft argon blowing time after calcium treatment is 4 min.

[0074] In Example 4, a steel sample is taken at the end of the argon station for composition analysis, and [sulfur] is 0.0070%; A steel sample is taken at the end of refining for composition analysis, and [sulfur] is 0.0029%; The refining cycle of the LF furnace is 35 min.

[0075] Comparative Example 1

[0076] Implemented in the manner of Example 1, the difference is that in Step S1, the end temperature is controlled at 1630 °C.

[0077] In Comparative Example 1, a steel sample was taken at the end of the argon station for composition analysis, and [sulfur] was 0.0225%; a steel sample was taken at the end of refining for composition analysis, and [sulfur] was 0.0057%; the refining cycle of the LF furnace was 54 min.

[0078] Comparative Example 2

[0079] It was carried out in the same manner as in Example 1, except that in step S1, the end temperature was controlled to be 1720 °C.

[0080] In Comparative Example 2, a steel sample was taken at the end of the argon station for composition analysis, and [sulfur] was 0.0151%; a steel sample was taken at the end of refining for composition analysis, and [sulfur] was 0.0032%; the refining cycle of the LF furnace was 43 min.

[0081] Comparative Example 3

[0082] It was carried out in the same manner as in Example 1, except that in step S2, based on the total volume of the molten steel being 100%, when the volume of the molten steel tapped was 10% of the total volume of the molten steel, ferrotitanium, carburizer, ferrosilicon and ferrosilicon manganese alloy were added to the molten steel tapped.

[0083] In Comparative Example 3, a steel sample was taken at the end of the argon station for composition analysis, and [sulfur] was 0.0177%; a steel sample was taken at the end of refining for composition analysis, and [sulfur] was 0.0052%; the refining cycle of the LF furnace was 44 min.

[0084] Comparative Example 4

[0085] It was carried out in the same manner as in Example 1, except that in step S2, based on the total volume of the molten steel being 100%, when the volume of the molten steel tapped was 50% of the total volume of the molten steel, ferrotitanium, carburizer, ferrosilicon and ferrosilicon manganese alloy were added to the molten steel tapped.

[0086] In Comparative Example 4, a steel sample was taken at the end of the argon station for composition analysis, and [sulfur] was 0.0214%; a steel sample was taken at the end of refining for composition analysis, and [sulfur] was 0.0058%; the refining cycle of the LF furnace was 49 min.

[0087] Comparative Example 5

[0088] It was carried out in the same manner as in Example 1, except that in step S2, based on the total volume of the molten steel being 100%, when the volume of the molten steel tapped was 30% of the total volume of the molten steel, lime and slag melting materials were added to the molten steel tapped.

[0089] In Comparative Example 5, a steel sample was taken at the end of the argon station for composition analysis, and [sulfur] was 0.0114%; a steel sample was taken at the end of refining for composition analysis, and [sulfur] was 0.0043%; the refining cycle of the LF furnace was 47 min.

[0090] Comparative Example 6

[0091] It was carried out in the same manner as in Example 1, except that in step S2, based on the volume of the total molten steel being 100%, when the volume of the molten steel tapped was 60% of the volume of the total molten steel, lime and slag melting materials were added to the molten steel tapped.

[0092] In Comparative Example 6, a steel sample was taken at the end of the argon station for composition analysis, and [sulfur] was 0.0213%; a steel sample was taken at the end of refining for composition analysis, and [sulfur] was 0.0041%; the refining cycle of the LF furnace was 55 min.

[0093] From the results of Examples 1 to 4 and Comparative Examples 1 to 6, it can be seen that by using the short-process argon station rapid deep desulfurization process method of the present invention, the desulfurization efficiency of the argon station is improved, rapid deep desulfurization of the argon station is achieved, the LF refining time is reduced, the sulfur component is stably controlled within 35 ppm, the refining process is simplified, the production cost is reduced, and it is more suitable for application in large-scale production.

[0094] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A short-process argon station rapid deep desulfurization process, characterized in that: The process comprises the following steps: Step S1, controlling the converter end temperature: limiting the end temperature, requiring the end temperature to be controlled to be 1650-1700° C.; Step S2, tapping after the converter blowing is completed, taking the volume of the total molten steel as 100%, when the volume of the tapped molten steel is 25-35% of the volume of the total molten steel, adding an alloy material containing an aluminum-iron alloy to the tapped molten steel, and when the volume of the tapped molten steel is 40-50% of the volume of the total molten steel, adding lime and slag-removing material to the tapped molten steel; Step S3: After the steel is tapped, the molten steel is transferred to the argon station, and aluminum iron and lime are added to the surface of the ladle slag. While the materials are being added, argon is blown and stirred at the bottom of the ladle.

2. The short-process argon station rapid deep desulfurization process according to claim 1 is characterized in that: In step S1, the end point temperature is 1695-1700°C; In step S2, steel is tapped after the converter blowing is completed, and the sulfur content in the molten steel is 0.015-0.040% before tapping.

3. The short-process argon station rapid deep desulfurization process according to claim 1 is characterized in that: In step S2, based on the volume of the total molten steel as 100%, when the volume of the tapped steel is 33.3% of the volume of the total molten steel, alloy materials containing aluminum-iron alloy are added to the tapped steel, and when the volume of the tapped steel is 50% of the volume of the total molten steel, lime and slag-forming materials are added to the tapped steel.

4. The short-process argon station rapid deep desulfurization process according to claim 3 is characterized in that: In step S2, when the composition and content of the molten steel are: C: 0.04-0.1%, Mn: 0.08-0.15%, P: 0.15-0.30%, S: 0.015-0.055%, and the rest are Fe elements and trace elements, an alloy material containing aluminum-iron alloy is added to the molten steel.

5. The short-process argon station rapid deep desulfurization process according to claim 1 is characterized in that: In step S2, the ratio of aluminum-iron alloy to molten steel is 2.1-3.3 kg / t, the ratio of lime to molten steel is 3.0-4.9 kg / t, and the ratio of slag-forming material to molten steel is 0.6-1.5 kg / t; The aluminum content in aluminum-iron alloy is 60-65%; The composition and content of the slag material are: CaO: 28-38%, Al2O3: 38-48%, SiO2: ≤10%, MgO: ≤5%, and the balance is Fe.

6. The short-process argon station rapid deep desulfurization process according to claim 5 is characterized in that: In step S2, the usage ratio of aluminum-iron alloy to molten steel is 2.42 kg / t, the usage ratio of lime to molten steel is 3.64 kg / t, and the usage ratio of slag-forming material to molten steel is 0.91 kg / t.

7. The short-process argon station rapid deep desulfurization process according to claim 6 is characterized in that: In step S3, the ratio of aluminum iron to ladle slag is 0.3-1.2 kg / t, and the ratio of lime to ladle slag is 1.1-2.7 kg / t; In step S3, the ratio of aluminum iron to ladle slag is 0.42 kg / t, and the ratio of lime to ladle slag is 2.42 kg / t.

8. The short-process argon station rapid deep desulfurization process according to claim 1 is characterized in that: In step S3, argon blowing and stirring are performed at the bottom of the ladle. The argon blowing and stirring time is 5 to 10 minutes, and the argon flow rate is controlled to be 800 to 1000 NL / min.

9. The short-process argon station rapid deep desulfurization process according to claim 1, characterized in that: The process method also includes: after the argon blowing and stirring at the bottom of the ladle are completed, the molten steel is transported to the LF furnace, and lime and steel aluminum shot are added to the surface of the ladle slag respectively, so that the sulfur content in the ladle slag is ≤50ppm, wherein the usage ratio of lime to ladle slag is 0.85-3.03kg / t, and the usage ratio of steel aluminum shot to ladle slag is 0.1-1.0kg / t; The aluminum content in the steel-aluminum shot is ≥99.5%.

10. The short-process argon station rapid deep desulfurization process according to claim 9, characterized in that: The process method also includes: after the sulfur content in the ladle slag is reduced to ≤50ppm, the molten steel is subjected to soft argon blowing and calcium treatment, wherein the soft argon blowing flow rate is controlled to be 50-200NL / min, and the argon flower diameter is ≤300mm; the soft argon blowing time before calcium treatment is 3-8min, and the soft argon blowing time after calcium treatment is 3-5min.