CN114854936A - LF (ladle furnace) rapid desulfurization method for HPB300 common carbon deformed steel bar - Google Patents
LF (ladle furnace) rapid desulfurization method for HPB300 common carbon deformed steel bar Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/064—Dephosphorising; Desulfurising
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/02—Dephosphorising or desulfurising
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/06—Deoxidising, e.g. killing
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/072—Treatment with gases
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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- Y02P10/20—Recycling
Abstract
The invention relates to the technical field of steel making, in particular to an LF (ladle furnace) rapid desulfurization method of HPB300 plain carbon deformed steel; adding a corresponding amount of high-alumina slag according to the corresponding relation between the content of the sample C in the argon station and the oxygen in the LF refining station so as to obtain good diffusion deoxidation efficiency corresponding to different C contents and promote desulfurization; and moreover, the high-aluminum slag is used for replacing a ferrosilicon powder deoxidizer on the silicon killed steel, so that the deoxidizing effect is obvious, the desulfurizing speed is synchronously accelerated, and the labor intensity of workers is effectively reduced. Meanwhile, the rapid desulfurization method provided by the invention also controls the addition amount of lime and the corresponding strong stirring time according to the content of the sample S in the argon station, so as to ensure efficient desulfurization.
Description
Technical Field
The invention relates to the technical field of steel making, in particular to an LF (ladle furnace) rapid desulfurization method for HPB300 plain carbon deformed steel.
Background
When the HPB300 plain carbon deformed steel bars (first-grade reinforcing steel bars, which are widely applied to civil engineering and building engineering) provided by the related technology are smelted, if the S content is not higher than the internal control standard, in order to reduce the production cost and ensure the efficiency, the argon station treatment is usually adopted; however, if the S content exceeds the standard, LF refining desulfurization treatment is also required.
HPB300 is silicon killed steel, and ferrosilicon powder or silicon carbide powder or carbon powder is generally adopted for diffusion deoxidation. The related art provides a process card specification for HPB 300: c range: 0.20% -0.24%, Si range: 0.15% -0.30%, Mn: 0.45-0.60%, P is less than or equal to 0.045%, S: less than or equal to 0.045%, C internal control: 0.20-0.23%, Si internal control: 0.15-0.25%, Mn internal control: 0.45-0.55 percent, P internal control is less than or equal to 0.040 percent, S internal control: 0.025%, target C: 0.22%, target Si: 0.20%, target Mn: 0.50%, target P: less than or equal to 0.035%, target S: less than or equal to 0.02 percent, requiring that the molten iron S is less than or equal to 0.035 percent, and when the S of the molten iron fed into the furnace is more than 0.025 percent, carrying out LF refining and S removal treatment; when the HPB300 is continuously cast with the aluminum-containing steel or used as a first furnace for casting, S of the LF refining station is required to be less than or equal to 0.010 percent. 150kg of ferrosilicon, 600kg of silicomanganese and 45kg of carbon powder are added when steel is tapped from the converter at 1/3. Tapping and slag washing: 400kg of lime and 400kg of bauxite. The LF slagging requirement is as follows: 400-600 kg fluorite balls; and (3) LF deoxidation requirement: adopting ferrosilicon powder to carry out diffusion deoxidation; calcium treatment requirements: when the pure calcium wire is continuously cast with the aluminum-containing steel or used as the first furnace for casting, the pure calcium wire is fed for 200 meters, when the first furnace for casting is continuously cast with the conventional HPB300, the pure calcium wire is fed for 100 meters, and the normal continuous casting furnace requires that the LF outlet S is less than or equal to 0.015 percent and the pure calcium wire is fed for 60 meters.
However, when the molten iron entering the furnace is more than 0.025 percent, particularly the molten iron S is not less than 0.035 percent, and the LF station leaving requirement S is not more than 0.010 percent, the LF adopts ferrosilicon powder for diffusion deoxidation, the deoxidation capability is weak, and white slag is not easy to produce; slag SiO 2 The method has the advantages of high alkalinity, low desulfurization speed, influence on production rhythm, high labor intensity of workers and incapability of meeting production requirements.
Disclosure of Invention
The invention aims to provide an LF rapid desulfurization method for HPB300 plain carbon deformed steel bar, which has a good diffusion deoxidation effect and has a promotion effect on desulfurization, so that the desulfurization speed can be increased, the production efficiency can be improved, the labor intensity of workers can be reduced, and the production requirement can be met.
The invention is realized by the following steps:
in a first aspect, the invention provides an LF rapid desulfurization method for HPB300 plain carbon deformed steel, which comprises the following steps:
1) carrying out deoxidation alloying on the molten steel by converter tapping, and adding slag washing materials;
2) sampling in an argon station after deoxidation and alloying;
3) when the LF refining temperature is more than or equal to the liquidus temperature plus 30 ℃, 11-grade power is transmitted for slagging, lime and fluorite balls are added in batches in the 11-grade power transmission process, and the lime and the fluorite balls are added within 3 minutes, wherein the lime is added according to the S content of an argon station sample, and the adding amount G1 (kg/ton steel) of the lime is 16000[ S ]%;
4) 3 minutes later, the power transmission is switched to 4 grades after 11 grades of power transmission is carried out for slagging, high-aluminum slag is added according to the C content of an argon station sample, and the adding amount of the high-aluminum slag G2 (kg/ton steel) is 0.4+ (0.15% - [ C ]%) x 400;
5) adding ferrosilicon;
6) blowing argon gas for strong stirring, wherein the flow of the argon gas is controlled to be 55-65m 3 H, controlling the exposed diameter of the molten steel surface to be 45-55 cm, and sampling 1; wherein the sampling temperature is more than the liquidus temperature and 60 ℃; determining strong stirring time according to the S content of the argon station sample, performing strong stirring for 2 minutes when the S content of the argon station sample is less than or equal to 0.020%, and performing strong stirring for 3-5 minutes when the S content of the argon station sample is more than 0.020%;
7) the ingredients are fine-tuned.
In an alternative embodiment, the sampling 1 step in step 6) comprises:
sticking slag by using an iron pipe, and directly sampling 1 when the white slag standard is achieved; and when the standard of the white slag is not met, adding ferrosilicon powder for deoxidation, and continuing to stir strongly for 1 minute until the top slag turns white and a sample is taken 1.
In an alternative embodiment, step 7) comprises: continuously heating to the temperature before weak stirring at 4 grades, stopping power supply, controlling the contents of C, Si and Mn according to the result of the sample 1, strongly stirring for 2 minutes, and keeping the argon flow at 55-65m 3 The exposed diameter of the molten steel surface is 45-55 cm, after strong stirring is carried out for 2 minutes, sampling is carried out for 2 minutes, weak stirring is carried out for 5 minutes, and the argon flow is 20-25 m 3 H, the exposed diameter of the molten steel surface is 20 cm.
In an optional embodiment, the addition amount of the ferrosilicon powder is 0.16-0.32 kg per ton of steel when the ferrosilicon powder is put into the converter for deoxidation.
In an alternative embodiment, step 1) is added with: lime 3.0-3.4 kg/ton steel, bauxite 3.0-3.4 kg/ton steel, ferrosilicon 1.0-1.4 kg/ton steel, silicomanganese 4.6-5.0 kg/ton steel and carbon powder 0.34-0.38 kg/ton steel.
In an optional embodiment, the high-aluminum slag in the step 4) comprises the following components: al is more than or equal to 40 percent, CaO: 10 to 15% of Al 2 O 3 ：10～20％，SiO 2 ≤6.0％，MgO≤3.0％，S≤0.50％，P≤0.50％。
In an optional embodiment, the step 4) of adding the high-aluminum slag is performed by adding the high-aluminum slag for 3-5 times.
In an alternative embodiment, in step 5), the ferrosilicon is added in an amount of: 0.142 (0.20% -argon station [ Si ]%) kg/ton steel.
In an optional embodiment, the slagging time in the step 5) is 8-12 minutes.
In an optional embodiment, the step 7) is followed by a step 8) of calcium treatment, wherein the soft blowing time during the calcium treatment is controlled to be 8-12 minutes, and the argon flow is 5-10 m 3 And h, keeping the molten steel surface not exposed.
The LF rapid desulfurization method for the HPB300 general carbon deformed steel bar has the following beneficial effects:
according to the rapid desulfurization method, the corresponding amount of high-alumina slag can be added according to the corresponding relation between the content of the sample C in the argon station and the oxygen in the LF refining station, so that good diffusion deoxidation efficiency can be obtained corresponding to different C contents, and desulfurization is promoted; and moreover, the high-aluminum slag is used for replacing a ferrosilicon powder deoxidizer on the silicon killed steel, so that the deoxidizing effect is obvious, the desulfurizing speed is synchronously accelerated, and the labor intensity of workers is effectively reduced. Meanwhile, the rapid desulfurization method provided by the invention also controls the addition amount of lime and the corresponding strong stirring time according to the content of the sample S in the argon station, so as to ensure efficient desulfurization.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The features and properties of the present invention are described in further detail below.
The LF rapid desulfurization method for the HPB300 general carbon deformed steel provided by the invention comprises the following steps:
1) the converter tapping is used for deoxidizing and alloying the molten steel, and slag washing materials are added.
2) After deoxidation and alloying, samples were taken at the argon station.
3) When the LF refining temperature is more than or equal to the liquidus temperature plus 30 ℃, 11-grade low-grade power transmission is performed for slagging, and 3 minutes later, high-grade 4-grade power transmission can be performed; in the 11-gear power transmission process, lime and fluorite balls are added in multiple batches (namely, a small amount of lime and fluorite balls are added in multiple batches), and the lime and the fluorite balls are completely added within 3 minutes; adding lime according to the content of S in an argon station sample, wherein when a preset condition is met, the adding amount of the lime G1 (kg/ton steel) is 16000[ S ]%;
in the prior art, the addition of lime depends on the sulfur content obtained by technicians according to sampling in an argon station, and due to the complexity of a desulfurization environment, the defects of insufficient desulfurization or excessive introduction of lime, which causes excessive increase of Ca and O contents, are often caused. The inventor of the invention discovers that 0.005 percent of lime can be desulfurized per 0.8 kg/ton of steel through a large amount of data collection and fitting analysis research of a steel-making process of HPB300 plain carbon deformed steel, namely, 0.005 percent of lime can be desulfurized in LF refining according to the lime dosage of 0.8 kg/ton of steel, and if 0.020 percent of the target value of the calorie S content of the HPB300 process is removed, 0.8 multiplied by 4 which is 3.2 kg/ton of steel is needed. Therefore, based on the S content of 0.020% in the argon station sample and the need to add 3.2kg lime per ton of steel, it can be seen that for every 0.005% increase in the S content of the argon station sample, 0.8kg lime needs to be added, and therefore, the amount of lime used per 0.8kg per ton of steel can be 0.005% to desulfurize, and thus the relationship between the addition amount of lime and the S content of the argon station sample can be expressed as: g1 (kg/ton steel) 3.2+16000 × ([ S ]% -0.020%), i.e. G1 (kg/ton steel) 16000[ S ]%. The formula is adopted to add lime, so that excessive introduction of lime materials can be avoided on the basis of guaranteeing effective desulfurization.
Further, the inventors have studied and found that the linearity of the data fitting is better when the following preset conditions are satisfied:
the basicity of the slag is controlled to be 3.0-3.5 (for example, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5) and Al 2 O 3 Controlled at 11% -16% (e.g. 11%, 12%, 13%, 14%, 15%, 16%, etc.), FeO + MnO < 1.5% (e.g. 1.45%, 1.40%, 1.35%, etc.);
② the Si content of the molten steel is more than or equal to 0.15 percent (for example, 0.15 percent, 0.16 percent, 0.18 percent, 0.20 percent and the like);
the sampling temperature of the argon station is more than or equal to the liquidus temperature plus 50 ℃;
the slag has good fluidity and is thin white slag or transparent glass slag;
fifthly, adding the materials for tapping and slag washing of the converter into the steel: lime 3.0-3.4 kg per ton steel, for example: 3.0 kg/ton steel, 3.2 kg/ton steel, 3.4 kg/ton steel, 3.0-3.4 kg/ton steel of bauxite, for example: 3.0 kg/ton steel, 3.2 kg/ton steel, 3.4 kg/ton steel;
sixthly, when the converter is tapped and washed with slag, the normal power transmission argon flow is 40-45 m 3 H, the exposed diameter of the molten steel surface: 28-32 cm, for example: 28cm, 29cm, 30cm, 31cm, 32cm, etc.; strong stirring for 3-5 min (e.g. 3min, 4min, 5 min), argon flow of 55-65m 3 H, for example: 55m 3 /h、58m 3 /h、60m 3 /h、65m 3 H, the exposed diameter of the molten steel surface: 45-55 cm, for example: 45cm, 50cm, 55cm, etc.;
the content of molten steel S is more than or equal to 0.030 percent (for example, 0.030 percent, 0.035 percent, 0.040 percent, 0.045 percent and the like).
4) 3 minutes later, the 11-grade power transmission is switched to 4-grade power transmission, and high-alumina slag is added according to the C content of the argon station sample for diffusion deoxidation.
The high and low C content of the argon station sample can reflect the strong and weak oxidizability of the molten steel. The inventor discovers through a large amount of data collection, fitting analysis and research of a steel-making process of the HPB300 plain carbon deformed steel:
when the C content of an argon station sample is 0.15 percent and the S content is 0.10 to 0.20 percent, the LF arrival station oxygen content is generally 25 to 30 ppm; from 2[ Al]+3[O]＝Al 2 O 3 (s) setting 30ppm oxygen removal per ton of steel requires the addition of x kg of aluminum, x ═ 2 × 27 × 1000 × 0.0030%)/(3 × 16), i.e. x ═ 0.34 kg/ton. The high-aluminum slag is added into the slag surface in a small amount in batches for diffusion deoxidation, the yield of the actually entering molten steel is lower, generally about 30 percent, and most of the rest is left in the slag for reaction; when 0.4kg of high-aluminum slag of steel of one ton is added, the Al content of the molten steel is as follows according to that the Al content of the high-aluminum slag is 33.8 percent and the Al yield of the molten steel is 30 percent: 0.4 × 33.81% × 30% ═ 0.041 (kg/ton steel). From the results of (0.041-0.034) ÷ 1000 ═ 0.0007% for Al in molten steel, it was found that 30ppm (0.0030%) of molten steel oxygen was removed by adding 0.4 kg/ton of high-alumina slag and that Als in molten steel was increased by 0.0007%, which means that Als was hardly increased when the C content was 0.15%.
Secondly, when the C content is 0.14 percent and the Si content is 0.10 to 0.20 percent, the oxygen content of the LF arrival station is generally 29 to 34 ppm; from 2[ Al]+3[O]＝Al 2 O 3 (s) setting removal of 34ppm per ton of steel requires addition of x kg of aluminium, x ═ 2 × 27 × 1000 × 0.0034%/3 × 16, i.e. x ═ 0.038 (kg/ton); the high-aluminum slag is added into the slag surface in a small amount in batches for diffusion deoxidation, the yield of the actually entering molten steel is lower, generally about 30 percent, and most of the rest is left in the slag for reaction; when 0.44 kg/ton of high-aluminum slag is added, the Al content of the molten steel is as follows according to that the high-aluminum slag contains Al 33.81 percent and the Al yield of the molten steel is 30 percent: 0.44 × 33.81% × 30% ═ 0.045 kg/ton steel. From the results of (0.045-0.038) ÷ 1000 ═ 0.0007% for molten steel, it was found that when the C content was 0.14%, 34ppm (0.0034%) of molten oxygen could be removed by adding 0.44 kg/ton of high-alumina slag, and that the amount of Als in molten steel was increased by 0.0007%, which means that the amount of Als was not increased.
Thirdly, the inventor obtains from the research results that the content of O increases by about 4ppm when the content of C decreases by 0.01 percent, and so on, and the formula is 2[ Al]+3[O]＝Al 2 O 3 (s) setting of 4ppm oxygen removal per ton of steel requires the addition of x kg aluminium, x ═ 2 × 27 × 1000 × 0.0004%)/3 × 16, i.e. x ═ 0.0045 kg/ton; according to the Al content of the high-aluminum slag of 33.81 percent and the Al yield of the molten steel of 30 percent, the amount of the high-aluminum slag added with 0.0045 kg/ton of aluminum is as follows: 0.0045/33.81%/0.30%/0.044 kg/ton steel. Therefore, based on the addition of 0.4 kg/ton of high-aluminum slag with the C content of 0.15%, the addition of 0.04 kg/ton of high-aluminum slag is increased for every 0.01% reduction of the C content, and the addition of 0.01% reduction of 0.04 kg/ton of high-aluminum slag is decreased for every 0.01% increase of the C content; from this, it is found that the amount of added high alumina slag G2 (kg/ton steel) is 0.4+ (0.15% - [ C ]]%) x 400. The addition of the high-alumina slag by the formula can ensure that the molten steel Als is hardly increased under the condition of ensuring effective deoxidation.
5) Adding high-aluminum slag and then adding ferrosilicon.
6) Blowing argon to stir strongly before sampling 1, wherein the flow of the argon is 55-65m 3 H, for example: 55m 3 /h、58m 3 /h、60m 3 /h、65m 3 The exposed diameter of the molten steel surface is 45-55 cm, for example: 45cm, 50cm, 55cm, etc. Sampling 1, wherein the sampling temperature is higher than the liquidus temperature and 60 DEG C. And determining strong stirring time according to the S content of the argon station sample, performing strong stirring for 2 minutes when the S content of the argon station sample is less than or equal to 0.020%, and performing strong stirring for 3-5 minutes when the S content of the argon station sample is more than 0.020%. The diffusion coefficient of sulfur in slag is increased by using the argon strong stirring kinetic condition, the interface reaction of steel slag is increased, and the desulfurization efficiency is higher.
The inventors' research shows that the above-mentioned control of the stirring time can further improve the desulfurization efficiency when the condition (r) -is satisfied, as in the step 3).
And 7) a fine tuning step.
According to the rapid desulfurization method, the corresponding amount of high-alumina slag can be added according to the corresponding relation between the content of the sample C in the argon station and the oxygen in the LF refining station, so that good diffusion deoxidation efficiency can be obtained corresponding to different C contents, and desulfurization is promoted; and moreover, the high-aluminum slag is used for replacing a ferrosilicon powder deoxidizer on the silicon killed steel, so that the deoxidizing effect is obvious, the desulfurizing speed is synchronously accelerated, and the labor intensity of workers is effectively reduced. Meanwhile, according to the content of the sample S in the argon station, the rapid desulfurization method provided by the invention researches a more accurate lime addition amount control method and an accurate stirring control method, further improves the desulfurization efficiency, is beneficial to the fine management of the process and reduces the cost.
Further, in the steps of 1) deoxidizing and alloying molten steel by converter tapping and adding slag washing materials, the addition of one of the recommended materials is as follows: lime 3.0 to 3.4 kg/ton steel (e.g., 3.0 kg/ton steel, 3.2 kg/ton steel, 3.4 kg/ton steel, etc.), bauxite 3.0 to 3.4 kg/ton steel (e.g., 3.0 kg/ton steel, 3.2 kg/ton steel, 3.4 kg/ton steel, etc.), ferrosilicon 1.0 to 1.4 kg/ton steel (e.g., 1.0 kg/ton steel, 1.2 kg/ton steel, 1.4 kg/ton steel, etc.), silicomanganese 4.6 to 5.0 kg/ton steel (e.g., 4.6 kg/ton steel, 4.8 kg/ton steel, 5.0 kg/ton steel, etc.), carbon powder 0.34 to 0.38 kg/ton steel (e.g., 0.34 kg/ton steel, 0.36 kg/ton steel, 0.38 kg/ton steel, etc.). The materials are added in proportion, so that the secondary oxidation of the molten steel can be avoided to obtain clean steel, and the desulfurization can be carried out.
In step 3), the amount of fluorite beads added was G1/2.5 to G1/3.5. Fluorite can reduce lime melting point, improves desulfurization partition coefficient, and then improves the desulfurization rate, and research shows, confirms the input amount of fluorite ball at 1/2.5 ~ 1/3.5 of lime quantity, can avoid the cost too high while, ensures that lime can not conglomerate, has good mobility, ensures desulfurization reaction power, ensures desulfurization efficiency.
The target value of the desulfurization in step 3) may be set to other values, and is not particularly limited as a reference index for the desulfurization target.
Further, in the step 4), in the 4-gear power transmission process, the high-aluminum slag can be added in small amount by 3-5 batches, and the high-aluminum slag is added within 3-5 minutes, so that the diffusion deoxidation effect can be effectively ensured.
Further, the high-aluminum slag comprises the following components: al is more than or equal to 40 percent, CaO: 10 to 15% of Al 2 O 3 ：10～20％，SiO 2 Less than or equal to 6.0 percent, less than or equal to 3.0 percent of MgO, less than or equal to 0.50 percent of S, less than or equal to 0.50 percent of P, and the balance of other impurities, wherein the specific components are similar to those of the related technology and are not repeated herein. The adaptive high-alumina slag component proportion can ensure the diffusion deoxidation efficiency so as to promote the desulfurization.
Further, in the step 5), according to the content of Si in the argon station sample, preparing HPB300 process card with the target content of Si of 0.20%, and further deoxidizing and alloying; according to the calculation of the addition amount of the alloy, ferrosilicon 0.142 kg/ton steel is required to be added when the silicon content of the molten steel is increased by 0.01 percent, and the added ferrosilicon amount is 0.142 x (0.20 percent to argon station [ Si ]%) kg/ton steel, the slagging time is 8-12 min, for example: 8min, 10min, 12min and the like.
Further, in the step 6), the slag is adhered by an iron pipe during sampling, the sample is directly sampled 1 when the white slag is white, and when the white slag standard is not met (for example: green translucent glass slag, etc.), adding ferrosilicon powder for deoxidation, continuing to stir strongly for 1 minute until the top slag becomes white, and sampling 1 to accurately meet the steel-making requirements.
It should be noted that the slag adhering and color observing steps can be repeated for many times, and if the slag adhering and color observing steps do not reach the white slag standard, the ferrosilicon powder can be added every time.
It should also be noted that in some embodiments, the iron pipe is used to stick the slag color, and the transparent glass slag can be directly sampled 1.
The deoxidation degrees of the white slag and the transparent glass slag are the same, and W (FeO + MnO) in the slag is less than 1%, wherein the transparent glass slag indicates that the slag is slightly dilute, and the white slag indicates that the slag is moderate, but the deoxidation of the white slag and the deoxidation of the slag are good, and the ferrosilicon powder can be used for deoxidation no longer, but direct sampling can be carried out.
Wherein, the addition of the ferrosilicon powder is recommended to be 0.16-0.32 kg/ton steel, for example: 0.16 kg/ton steel, 0.18 kg/ton steel, 0.2 kg/ton steel, 0.24 kg/ton steel, 0.28 kg/ton steel, 0.3 kg/ton steel, 0.32 kg/ton steel, etc. In this way, a good deoxidation effect can be further ensured.
Further, the fine tuning component in step 7) may specifically include: continuously heating for 4 grades to the temperature before weak stirring, and cutting off the power; according to the result of the sample 1, the contents of C, Si and Mn are respectively controlled, namely the contents of C, Si and Mn are respectively controlled at target values, strong stirring is carried out for 2 minutes, and the flow of argon is 55-65m 3 H, for example: 55m 3 /h、58m 3 /h、60m 3 /h、65m 3 The exposed diameter of the molten steel surface is 45-55 cm, for example: 45cm, 50cm, 55cm and the like to ensure that the components of the molten steel are uniform; after strong stirring for 2 minutes, sampling for 2 minutes, weak stirring for 5 minutes, wherein the flow of argon is 20-25 m 3 H, for example: 20m 3 /h、22m 3 /h、25m 3 H, etc. the exposed diameter of the molten steel surface is 20cm, so that the molten steel inclusion can further float upwards.
Further, the LF rapid desulfurization method of the HPB300 general carbon deformed steel also comprises the following steps: 8) and (4) calcium treatment.
And further, in the calcium treatment, the soft blowing time is prolonged by 5 minutes and is controlled to be 8-12 minutes, for example: 8 minutes, 10 minutes, 12 minutes and the like, and the flow of argon is 5-10 m 3 H, for example: 5m 3 /h、8m 3 /h、10m 3 And h, the exposed diameter of the molten steel surface is 0cm, namely the molten steel surface is not exposed.
The present invention will be explained in more detail with reference to specific examples and comparative examples.
Example 1
(120tLF) argon station sample C: 0.08%, Si: 0.06%, Mn: 0.45%, S0.035%, Als: 0.001 percent and LF arrival temperature of 1544 ℃ (the temperature is not less than the liquidus temperature plus 30℃)) 11-grade power transmission for slagging, 3 minutes later, the power transmission is switched to high-grade 4-grade power transmission, and the flow of power transmission argon is 40-45 m 3 H, the exposed diameter of the molten steel surface is 30 cm; the adding amount of lime in LF refining is 672kg, the adding amount of fluorite balls is 269kg, the adding amount of high-alumina slag is 82kg, and the adding amount of ferrosilicon is 238 kg. Heating to 1580 ℃ (liquidus temperature +60 ℃), and stopping power supply; argon blowing and strong stirring are carried out for 4 minutes, and the flow of the argon is 60m 3 H, the exposed diameter of the molten steel surface is 50 cm; the slag is stuck by the iron pipe after the strong stirring, the slag is transparent glass slag, and the sampling is 1, C: 0.09%, S: 0.003%, Si: 0.16%, Mn: 0.46%, Als: 0.002%. According to the result of sample 1, the contents of C, Si and Mn are required to be controlled at target values respectively, and 187kg of carbon powder, 86kg of ferrosilicon and 75kg of high-carbon ferromanganese are added; stirring strongly for 2 minutes with argon flow of 60m 3 H, the exposed diameter of the molten steel surface: 50 cm. After the strong stirring, sampling 2; weakly stirring for 5 minutes, wherein the flow of argon is 20-25 m 3 H, the exposed diameter of the molten steel surface: 20 cm. It took 17 minutes to remove S.
Example 2
(120tLF) argon station sample C: 0.06%, Si: 0.09%, Mn 0.48%, S: 0.040%, Als: 0.001 percent, the LF arrival temperature is 1550 ℃ (not less than the liquidus and 30 ℃), 11-grade power transmission is used for slagging, the position is shifted to high-grade 4-grade power transmission after 3 minutes, and the flow of the power transmission argon is 40-45 m 3 H, the exposed diameter of the molten steel surface: 30 cm; the addition amount of LF added lime is 768kg, the addition amount of fluorite is 308kg, the addition amount of high-alumina slag is 120kg, and the addition amount of ferrosilicon is 188 kg. Heating to 1585 ℃ (liquidus and 60 ℃), and stopping power supply; argon blowing and strong stirring are carried out for 5 minutes, and the flow of the argon is 60m 3 H, the exposed diameter of the molten steel surface: 50 cm; stirring completely, adhering slag and thin white slag, and sampling 1, C: 0.07%, Si: 0.15%, Mn: 0.49%, S: 0.004%, Als: 0.002%. According to the result of sampling 1, the contents of C, Si and Mn are respectively controlled at target values, and 218kg of carbon powder, 102kg of ferrosilicon and 18kg of high-carbon ferromanganese are added; stirring strongly for 2 minutes with argon flow of 60m 3 H, the exposed diameter of the molten steel surface: 50 cm. After the strong stirring, sampling 2; weakly stirring for 5 minutes, wherein the flow of argon is 20-25 m 3 H, the exposed diameter of the molten steel surface: 20 cm. It took 18 minutes to remove S.
Comparative example
(120tLF) argon station sample C: 0.10 percent,Si: 0.09%, Mn 0.45%, S: 0.037%, Als: 0.001 percent, the LF arrival temperature of 1546 ℃ (not less than the liquidus and 30 ℃), 11-grade electricity is used for slagging, the temperature is changed to high-grade 4-grade electricity after 3 minutes, and the flow of the electricity-transmitted argon is 40-45 m 3 H, the exposed diameter of the molten steel surface: 30 cm; the addition amount of LF added lime is 1001kg, the addition amount of fluorite is 355kg, and the addition amount of ferrosilicon powder is 150 kg. Heating to 1585 deg.C (liquidus and 60 deg.C), and stopping power supply. Strong argon blowing stirring is carried out for 8 minutes, and the flow of argon is 60m 3 H, the exposed diameter of the molten steel surface: 50 cm. The slag is stuck after the strong stirring, the green translucent glass slag is sampled 1 and C: 0.119%, Si: 0.08%, S: 0.008%, Mn 0.46%, Als: 0.001 percent. According to the result of sampling 1, the contents of C, Si and Mn are controlled to target values, and 145kg of carbon powder, 203kg of ferrosilicon and 71kg of high-carbon ferromanganese are added. Stirring strongly for 3 minutes with argon flow of 60m 3 H, the exposed diameter of the molten steel surface: 50 cm. After strong stirring, sampling 2, stirring for 5 minutes in a weak way, wherein the argon flow is 20-25 m 3 H, the exposed diameter of the molten steel surface: 20 cm. It took 23 minutes to remove S.
In conclusion, according to the LF rapid desulfurization method for the HPB300 general carbon deformed steel bar, the corresponding high-aluminum slag addition amount is determined according to the corresponding relation between the content of the sample C in the argon station and the oxygen in the LF arrival station. The high-aluminum slag is uniformly added on the slag surface in a plurality of batches and in a small amount in the early stage, so that the good diffusion deoxidation effect is achieved, and the S removal is promoted. Simultaneously improves Al in the slag 2 O 3 The concentration (11-16%) makes the spreading performance of the slag better and the impurity adsorption capacity stronger. The yield of the high-aluminum slag actually entering the molten steel is lower by about 30 percent, and almost no Als is added except for removing the oxygen in the molten steel, so the content of Als at the outlet is low and is less than 0.004 percent. Al remaining in molten steel 2 O 3 High-alkalinity white slag (3.0-3.5) with good fluidity is gathered and floated for a long time under the argon stirring dynamic condition, and the feeding of a pure calcium wire into molten steel is calcified after the refining process is finished, so that Al is changed 2 O 3 The form of the inclusions is prolonged, and the soft blowing time is prolonged to further purify the molten steel. Therefore, the nodulation phenomenon does not occur in the molten steel casting under the desulfurization method of the invention.
And then, determining the corresponding lime adding amount when the preset condition is met through the S content of the argon station sample so as to ensure effective and rapid desulfurization through lime addition.
Moreover, the corresponding strong stirring time is determined when the content of the sample S in the argon station meets the preset condition, and effective and rapid desulfurization is ensured through the strong stirring time of different times.
Finally, the desulfurization method breaks through the tradition, the ferrosilicon powder deoxidizer is replaced by the high-aluminum slag on the silicon killed steel, the deoxidation effect is obvious, the desulfurization speed is accelerated, and the labor intensity of workers is reduced.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. An LF rapid desulfurization method for HPB300 plain carbon deformed steel bar is characterized by comprising the following steps:
1) carrying out deoxidation alloying on the molten steel by converter tapping, and adding slag washing materials;
2) sampling in an argon station after deoxidation and alloying;
3) when the LF refining temperature is more than or equal to the liquidus temperature plus 30 ℃, 11-grade power is transmitted for slagging, lime and fluorite balls are added in batches in the 11-grade power transmission process, and the lime and the fluorite balls are added within 3 minutes, wherein the lime is added according to the S content of an argon station sample, and the adding amount G1 (kg/ton steel) of the lime is 16000[ S ]%;
4) 3 minutes later, carrying out electric slagging at 11 grades, then carrying out electric slagging at 4 grades, and adding high-aluminum slag according to the C content of an argon station sample, wherein the adding amount of the high-aluminum slag G2 (kg/ton steel) is 0.4+ (0.15% - [ C ]%). times.400;
5) adding ferrosilicon;
6) blowing argon gas for strong stirring, wherein the flow of the argon gas is controlled to be 55-65m 3 The exposed diameter of the molten steel surface is controlled to be 45-55 cm, and sampling is carried out for 1; wherein the sampling temperature is more than the liquidus temperature and 60 ℃; determining strong stirring time according to the S content of the argon station sample, performing strong stirring for 2 minutes when the S content of the argon station sample is less than or equal to 0.020 percent, and performing strong stirring for 2 minutes when the S content of the argon station sample is less than or equal to 0.020 percentStrongly stirring for 3-5 minutes when the S content of the argon station sample is more than 0.020%;
7) the ingredients are fine-tuned.
2. The method for LF fast desulfurization of HPB300 plain carbon deformed steel bar according to claim 1, characterized in that the sampling 1 step in the step 6) comprises:
sticking slag by using an iron pipe, and directly sampling 1 when the white slag standard is achieved; when the standard of the white slag is not met, the ferrosilicon powder is added for deoxidation, strong stirring is continued for 1 minute until the top slag turns white, and a sample is taken 1.
3. The LF rapid desulfurization method for HPB300 plain carbon deformed steel bar according to claim 1, characterized in that the step 7) includes: continuously heating to the temperature before weak stirring at 4 grades, stopping power supply, controlling the contents of C, Si and Mn according to the result of the sample 1, strongly stirring for 2 minutes, and keeping the argon flow at 55-65m 3 The exposed diameter of the molten steel surface is 45-55 cm, after strong stirring is carried out for 2 minutes, sampling is carried out for 2 minutes, weak stirring is carried out for 5 minutes, and the argon flow is 20-25 m 3 And h, the exposed diameter of the molten steel surface is 20 cm.
4. The LF rapid desulfurization method of HPB300 plain carbon deformed steel bar as set forth in claim 2,
and the addition amount of the ferrosilicon powder is 0.16-0.32 kg per ton of steel when the ferrosilicon powder is added for deoxidation.
5. The LF rapid desulfurization method of HPB300 plain carbon deformed steel bar according to claim 1,
adding the following components in the step 1): lime 3.0-3.4 kg/ton steel, bauxite 3.0-3.4 kg/ton steel, ferrosilicon 1.0-1.4 kg/ton steel, silicomanganese 4.6-5.0 kg/ton steel and carbon powder 0.34-0.38 kg/ton steel.
6. The LF rapid desulfurization method of HPB300 plain carbon deformed steel bar according to claim 1,
the high-aluminum slag in the step 4) comprises the following components: al is more than or equal to 40 percent, CaO: 10 to 15% of Al 2 O 3 ：10～20％，SiO 2 ≤6.0％，MgO≤3.0％，S≤0.50％，P≤0.50％。
7. The LF rapid desulfurization method of HPB300 plain carbon deformed steel bar according to claim 1,
and 4) adding the high-aluminum slag in the step 4) for 3-5 times.
8. The LF rapid desulfurization method of HPB300 plain carbon deformed steel bar according to claim 1,
in the step 5), the content of the added ferrosilicon is as follows: 0.142 (0.20% -argon station [ Si ]%) kg/ton steel.
9. The LF rapid desulfurization method of HPB300 plain carbon deformed steel bar according to claim 8,
and the slag melting time of the step 5) is 8-12 minutes.
10. The LF rapid desulfurization method of HPB300 plain carbon deformed steel bar according to claim 1 or 2,
step 7) is followed by step 8) of calcium treatment, wherein the soft blowing time during the calcium treatment is controlled to be 8-12 minutes, and the argon flow is 5-10 m 3 And h, keeping the molten steel surface not exposed.
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