Production method for deoxidizing and alloying pig iron for converter

Abstract

The invention belongs to the technical field of ferrous metallurgy, and particularly discloses a deoxidation alloying production method of pig iron for a converter, which comprises the steps of selecting pig iron components and controlling the smelting process of the converter, and specifically comprises the following contents: the selected pig iron components comprise 3.8-4.2% of C, 1.2-1.8% of Si, 0.8-1.2% of Mn, 0.08-0.12% of V, less than or equal to 0.08% of P and less than or equal to 0.03% of S; the final temperature is estimated according to the pig iron adding amount of molten steel components, and the scrap steel adding amount is controlled according to the estimated result. HRB400E is used as a key material for buildings, components are required to be accurately controlled, mechanical properties are stable, anti-seismic indexes reach the standard, and component uniformity optimization, temperature stability and deoxidation inclusion control of molten steel can be achieved through the pig iron deoxidation alloying process; through cooperative regulation and control of the pig iron amount and the scrap steel amount, the converter end point temperature and molten steel components can be stabilized, smelting fluctuation is reduced, and meanwhile reasonable introduction of the V element is beneficial to optimization of the mechanical property of steel and improvement of the product quality stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel metallurgy, in particular to a production method of pig iron deoxidization and alloying for converter. BACKGROUND

[0002] HRB400E (hot-rolled ribbed steel bar anti-seismic type) is a key load-bearing material in building structures, which needs to meet the "E" grade anti-seismic performance requirements of the strength-to-ductility ratio ≥ 1.25, the maximum force total elongation rate ≥ 9%, and the yield strength ratio ≤ 0.85, and thus is forced to be popularized in high-rise buildings, bridges and other projects in earthquake-prone areas. According to the statistical data of China Iron and Steel Association in 2024, the annual demand of domestic HRB400E has broken through 120 million tons, accounting for more than 65% of the total consumption of deformed steel bars, and has become the main product of steelmaking production, and the cost of its steel grade is directly related to the overall cost control of the steelmaking process.

[0003] At present, the traditional smelting process of HRB400E steel mainly takes "converter → LF refining → continuous casting" as the main line. In terms of composition control, the target composition is realized by adding carbon powder, ferrosilicon, silicon manganese, composite vanadium nitrogen, vanadium nitrogen alloy and the like; in terms of raw materials, the converter smelting takes pig iron as the main metal material, and the proportion is about 70%, and the composition range of pig iron is C: 3.5-4.2%, Si: 0.4-1.5%, Mn: 0.5-1.2%, V: 0.05-0.10%.

[0004] There are two major deficiencies in the existing smelting process: first, the alloy cost proportion is high, and high-priced alloys such as ferrosilicon (6200 yuan / ton), manganese iron (5870 yuan / ton), vanadium-nitrogen alloy (120,000 yuan / ton) and the like are consumed in the production process, resulting in that the alloy cost accounts for about 30% of the total cost of the steelmaking process; second, the utilization rate of pig iron is low, and in the converter smelting, the C, Si, Mn and V elements in the pig iron are easy to be oxidized to cause chemical loss, accounting for 40%-60%, and the converter spatter will cause 10%-30% mechanical loss, and the double losses result in that the pig iron recovery rate is only 90%-92%. The large consumption of high-priced alloys in the existing smelting process and the low recovery rate caused by the oxidation of beneficial elements and spatter of pig iron jointly push up the consumption of steel materials, and finally cause the high cost of the steelmaking process of HRB400E steel, which restricts the product market competitiveness and production benefit improvement. Therefore, it is urgent to provide a smelting process of HRB400E steel which can reduce the consumption of alloys and steel materials and effectively control the cost of the steelmaking process. SUMMARY

[0005] The present application relates to the technical field of steel metallurgy, in particular to a production method of pig iron deoxidization and alloying for converter. BACKGROUND

[0002] HRB400E (hot-rolled ribbed steel bar anti-seismic type) is a key load-bearing material in building structures, which needs to meet the "E" grade anti-seismic performance requirements of the strength-to-ductility ratio ≥ 1.25, the maximum force total elongation rate ≥ 9%, and the yield strength ratio ≤ 0.85, and thus is forced to be popularized in high-rise buildings, bridges and other projects in earthquake-prone areas. According to the statistical data of China Iron and Steel Association in 2024, the annual demand of domestic HRB400E has broken through 120 million tons, accounting for more than 65% of the total consumption of deformed steel bars, and has become the main product of steelmaking production, and the cost of its steel grade is directly related to the overall cost control of the steelmaking process.

[0003] At present, the traditional smelting process of HRB400E steel mainly takes "converter → LF refining → continuous casting" as the main line. In terms of composition control, the target composition is realized by adding carbon powder, ferrosilicon, silicon manganese, composite vanadium nitrogen, vanadium nitrogen alloy and the like; in terms of raw materials, the converter smelting takes pig iron as the main metal material, and the proportion is about 70%, and the composition range of pig iron is C: 3.5-4.2%, Si: 0.4-1.5%, Mn: 0.5-1.2%, V: 0.05-0.10%.

[0004] There are two major deficiencies in the existing smelting process: first, the alloy cost proportion is high, and high-priced alloys such as ferrosilicon (6200 yuan / ton), manganese iron (5870 yuan / ton), vanadium-nitrogen alloy (120,000 yuan / ton) and the like are consumed in the production process, resulting in that the alloy cost accounts for about 30% of the total cost of the steelmaking process; second, the utilization rate of pig iron is low, and in the converter smelting, the C, Si, Mn and V elements in the pig iron are easy to be oxidized to cause chemical loss, accounting for 40%-60%, and the converter spatter will cause 10%-30% mechanical loss, and the double losses result in that the pig iron recovery rate is only 90%-92%. The large consumption of high-priced alloys in the existing smelting process and the low recovery rate caused by the oxidation of beneficial elements and spatter of pig iron jointly push up the consumption of steel materials, and finally cause the high cost of the steelmaking process of HRB400E steel, which restricts the product market competitiveness and production benefit improvement. Therefore, it is urgent to provide a smelting process of HRB400E steel which can reduce the consumption of alloys and steel materials and effectively control the cost of the steelmaking process. SUMMARY

[0005] The present application relates to the technical field of steel metallurgy, in particular to a production method of pig iron deoxidization and alloying for converter. BACKGROUND

[0002] HRB400E (hot-rolled ribbed steel bar anti-seismic type) is a key load-bearing material in building structures, which needs to meet the "E" grade anti-seismic performance requirements of the strength-to-ductility ratio ≥ 1.25, the maximum force total elongation rate ≥ 9%, and the yield strength ratio ≤ 0.85, and thus is forced to be popularized in high-rise buildings, bridges and other projects in earthquake-prone areas. According to the statistical data of China Iron and Steel Association in 2024, the annual demand of domestic HRB400E has broken through 120 million tons, accounting for more than 65% of the total consumption of deformed steel bars, and has become the main product of steelmaking production, and the cost of its steel grade is directly related to the overall cost control of the steelmaking process.

[0003] At present, the traditional smelting process of HRB400E steel mainly takes "converter → LF refining → continuous casting" as the main line. In terms of composition control, the target composition is realized by adding carbon powder, ferrosilicon, silicon manganese, composite vanadium nitrogen, vanadium nitrogen alloy and the like; in terms of raw materials, the converter smelting takes pig iron as the main metal material, and the proportion is about 70%, and the composition range of pig iron is C: 3.5-4.2%, Si: 0.4-1.5%, Mn: 0.5-1.2%, V: 0.05-0.10%.

[0004] There are two major deficiencies in the existing smelting process: first, the alloy cost proportion is high, and high-priced alloys such as ferrosilicon (6200 yuan / ton), manganese iron (5870 yuan / ton), vanadium-nitrogen alloy (120,000 yuan / ton) and the like are consumed in the production process, resulting in that the alloy cost accounts for about 30% of the total cost of the steelmaking process; second, the utilization rate of pig iron is low, and in the converter smelting, the C, Si, Mn and V elements in the pig iron are easy to be oxidized to cause chemical loss, accounting for 40%-60%, and the converter spatter will cause 10%-30% mechanical loss, and the double losses result in that the pig iron recovery rate is only 90%-92%. The large consumption of high-priced alloys in the existing smelting process and the low recovery rate caused by the oxidation of beneficial elements and spatter of pig iron jointly push up the consumption of steel materials, and finally cause the high cost of

[0006] To achieve the above object, the basic scheme provided by the present application is a production method for deoxidation and alloying of pig iron for converter, which comprises selecting the composition of pig iron and controlling the converter smelting process, and specifically comprises the following contents: Selecting the composition of pig iron: the selected composition of pig iron is C: 3.8-4.2%, Si: 1.2-1.8%, Mn: 0.8-1.2%, V: 0.08-0.12%, P≤0.08%, S≤0.03%; Controlling the converter smelting process: according to the amount of pig iron added according to the composition of molten steel, the end temperature is budgeted, and the amount of scrap steel is controlled according to the budget result.

[0007] The working principle of the present application is that: the process precisely selects pig iron with specific composition, utilizes the deoxidation ability of elements such as Si and the micro-alloying potential of V, and strictly limits the content of harmful elements P and S to lay the foundation of steel quality; in the converter smelting process, the amount of pig iron is determined according to the target composition of molten steel, and the amount of scrap steel is adjusted by budgeting the end temperature, so as to realize the double control of heat balance and molten steel composition in the smelting process, thereby completing the deoxidation and alloying process.

[0008] The beneficial effects of the present application are that: the precise selection of pig iron composition can fully utilize the effects of each element, reduce the amount of additional alloy added subsequently, reduce production cost, and the low P and S content can significantly improve the purity of molten steel; through the synergistic regulation of the amount of pig iron and scrap steel, the end temperature and the composition of molten steel in the converter can be stabilized, the smelting fluctuation can be reduced, the production efficiency can be improved, and the reasonable introduction of V element helps to optimize the mechanical properties of steel and improve the product quality stability.

[0009] Scheme two, which is the preferred embodiment of the basic scheme, the specific operation steps of controlling the converter smelting are as follows: S1: measuring the composition and temperature of molten steel after converter smelting, adding a small amount of alloying material according to the composition of molten steel, and alloying molten steel; S2: presetting the target composition and temperature of molten steel, and measuring the composition and temperature of molten steel after adding alloying material, calculating the required amount of pig iron according to the measurement result by using alloying model calculation method; S3: adding the calculated amount of pig iron into the ladle in batches to stabilize the temperature of molten steel; S4: after the added pig iron is completely melted, sampling and measuring the temperature again, and supplementing the required elements in a small amount according to the measurement result.

[0010] Scheme three, which is the preferred embodiment of scheme two, the specific steps of calculating the required amount of pig iron in step S2 by using alloying model calculation method are as follows: a: based on the composition balance calculation formula, calculating the required amount of pig iron to meet the target composition of each element: (1) Where Ws is the initial weight of molten steel, Wpi is the amount of pig iron required to meet the target composition of the element, [i]s_initial is the initial composition of molten steel, [i]p is the pig iron composition, [i]s_target is the target composition of molten steel, and ηi is the element yield; b: After calculating the required amount of pig iron for all elements, take the minimum value as the required amount of pig iron under compositional balance (Wp). temperature ); c: Based on the heat balance calculation formula, the maximum amount of pig iron that can be added under stable molten steel temperature is calculated: (2) Where Wp_max is the maximum amount of pig iron, Cp_steel is the specific heat capacity of molten steel (approximately 0.22 kcal / kg·℃), Cp_pig is the specific heat capacity of pig iron (approximately 0.15 kcal / kg·℃), T_initial is the initial temperature of molten steel, T_final is the target temperature of molten steel, T_pig is the initial temperature of pig iron (usually room temperature 25℃), T_melt is the melting temperature of pig iron (approximately 1150℃), and ΔH_melt is the latent heat of molten iron (approximately 50 kcal / kg). d: Compare the amount of pig iron under compositional equilibrium and the maximum amount of pig iron under thermal equilibrium, and take the smaller value as the final amount of pig iron added.

[0011] Option 4, which is the preferred option of Option 3, has the following target steel composition: C: 0.22%-0.25%, Si: 0.33%-0.48%, Mn: 1.33%-1.48%, V: 0.020%-0.038%, P≤0.045%, S≤0.045%, and the steel temperature is controlled at 1560℃-1600℃.

[0012] Option 5, which is the preferred option of Option 2, involves controlling the amount of pig iron added in each batch to be ≤500kg in step S3.

[0013] Option 6, which is the preferred option of Option 5, involves adding pig iron in step S3 while simultaneously blowing argon gas and stirring. The argon gas flow rate is 10-20 L / min, and the stirring time is 3-5 min.

[0014] Option 7, which is a preferred option of Option 2, involves adding alloy additives in step S4 by using a wire feeding method or a powder spraying method when supplementing the required elements in small quantities. After supplementation, the deviation of the molten steel composition is controlled within ±0.01% of the target value. Attached Figure Description

[0015] Figure 1 This is a flowchart of a production method for deoxidizing and alloying pig iron for converters according to the present invention. Detailed Implementation

[0016] The present invention will be further described in detail below through specific embodiments: Example 1 like Figure 1 The method shown is a production method for deoxidizing and alloying pig iron for converters, including selecting pig iron composition and controlling the converter smelting process, specifically including the following: Selection of pig iron composition: The selected pig iron composition is C: 3.8-4.2%, Si: 1.2-1.8%, Mn: 0.8-1.2%, V: 0.08-0.12%, P≤0.08%, S≤0.03%; Controlling the converter smelting process: Based on the steel composition, the amount of pig iron added is calculated to determine the final temperature. The amount of scrap steel added is then controlled according to the calculated result. Specific operating steps are as follows: S1: Measure the composition and temperature of the molten steel after converter smelting. Based on the initial steel composition, add a small amount of alloying material to alloy the steel. The target composition for 12-25mm HRB400E steel is: C: 0.22%-0.25%, Si: 0.33%-0.43%, Mn: 1.33%-1.43%, V: 0.020%-0.028%, P≤0.045%, S≤0.045%. Control the molten steel temperature at 1560℃-1600℃. The specific steps are as follows: a: Based on the component balance calculation formula, calculate the required amount of each element to meet the target component: (1) Where Ws is the initial weight of molten steel, Wpi is the amount of pig iron required to meet the target composition of the element, [i]s_initial is the initial composition of molten steel, [i]p is the pig iron composition, [i]s_target is the target composition of molten steel, and ηi is the element yield; b: After calculating the required amount of pig iron for all elements, take the minimum value as the required amount of pig iron under compositional balance. c: Based on the heat balance calculation formula, the maximum amount of pig iron that can be added under stable molten steel temperature is calculated: (2) Where Wp_max is the maximum amount of pig iron, Cp_steel is the specific heat capacity of molten steel (approximately 0.22 kcal / kg·℃), Cp_pig is the specific heat capacity of pig iron (approximately 0.15 kcal / kg·℃), T_initial is the initial temperature of molten steel, T_final is the target temperature of molten steel, T_pig is the initial temperature of pig iron (usually room temperature 25℃), T_melt is the melting temperature of pig iron (approximately 1150℃), and ΔH_melt is the latent heat of molten iron (approximately 50 kcal / kg). d: Compare the amount of pig iron under compositional equilibrium and the maximum amount of pig iron under thermal equilibrium, and take the smaller value as the final amount of pig iron added; S2: Preset the target composition and temperature of molten steel, and measure the composition and temperature of molten steel after adding alloy materials. Based on the measurement results, calculate the required amount of pig iron to be added using the alloy model calculation method. S3: Add the calculated amount of pig iron to the ladle in batches, controlling the amount of pig iron added in each batch to be ≤500kg. When adding pig iron, argon gas is blown and stirred at the same time. The argon gas flow rate is 12-16L / min and the stirring time is 3.5min to stabilize the temperature of the molten steel. S4: After the added pig iron has completely melted, take another sample to measure the temperature. Based on the measurement results, use the wire feeding method or powder injection method to supplement the required elements in small amounts. After supplementation, the deviation of the molten steel composition is controlled within ±0.01% of the target value.

[0017] The implementation method of this embodiment is as follows: When implementing this production process, the specific production parameters must first be determined: Nominal converter capacity: 70t; Production batch: 70t of molten steel per furnace; Pig iron raw material composition: C: 4.1%, Si: 1.6%, Mn: 1.1%, V: 0.11%, P: 0.07%, S: 0.025%; Element yield: ηC=94%, ηSi=86%, ηMn=91%, ηV=82%, ηP=97%, ηS=96%.

[0018] After the converter smelting was completed, the molten steel was poured into a 70t ladle, and a sample of the molten steel was immediately collected using a sampling gun. The initial composition was detected by a direct spectrometer and found to be: C: 0.19%, Si: 0.28%, Mn: 1.02%, V: 0.010%, P: 0.032%, S: 0.028%. At the same time, the initial temperature of the molten steel was measured to be 1595℃ using an infrared thermometer.

[0019] According to the national standard and internal control requirements of HRB400E steel, the target composition of molten steel was set as C: 0.23%, Si: 0.35%, Mn: 1.37%, V: 0.021%, P≤0.045%, S≤0.045% in the alloy batching calculation system, and the target temperature was set as 1580℃. Then, the initial temperature, initial composition, target composition, and element yield of the molten steel were input into the system, and the required amount of pig iron for each element was calculated according to formula (1): ; ; ; If the denominator is negative, the Mn content of pig iron is lower than the target value. Adding pig iron will reduce the Mn content. Take infinity, no constraints. The required amount of pig iron is greater than 10,000 kg.

[0020] After screening, the minimum required amount of pig iron for each element was found to be 769 kg for element C, which was taken as the required amount of pig iron under compositional balance.

[0021] Then, the alloy batching calculation system is used to perform heat balance calculation. Preset parameters such as the specific heat capacity of molten steel, the specific heat capacity of pig iron, the initial temperature, and the target temperature are input. The maximum amount of pig iron under heat balance is calculated according to formula (2): Comparing the composition balance amount of 769 kg with the maximum heat balance amount of 737 kg, the smaller value of 737 kg is taken, which is rounded up to 740 kg. 740 kg of pig iron is added to the ladle via a chute, while 60 kg of a silicon-manganese alloy containing 65% Mn and 18% Si is added via a quantitative feeder. After standing for 3 minutes, the composition and temperature of the molten steel are measured again. The measured composition of the molten steel is: C: 0.218%, Si: 0.32%, Mn: 1.25%, V: 0.016%, P: 0.034%, S: 0.029%, the temperature is 1583℃, and the weight is 70800 kg.

[0022] The results were input again into the alloy proportioning calculation system. Considering the composition requirements for the 12-25mm specification, the required amount of pig iron was determined to be 120kg. Then, the 120kg of pig iron was slowly added in batches to the lower part of the ladle via a chute to avoid splashing of molten steel. Simultaneously, the bottom-blowing argon system of the ladle was activated, employing a three-stage stirring pattern: weak-strong-weak. The stirring speed was 12L / min for 1 minute initially, 15L / min for 1.5 minutes in the middle stage, and 13L / min for 1 minute in the later stage, for a total of 3.5 minutes. During the stirring process, the molten steel temperature was monitored in real time using an infrared thermometer to ensure it remained stable at approximately 1580℃.

[0023] The entire process involved observing the molten steel surface with an industrial camera and monitoring the temperature with an infrared thermometer. After confirming that the pig iron was completely melted, the composition and temperature were checked again. The molten steel composition was measured to be: C: 0.227%, Si: 0.34%, Mn: 1.35%, V: 0.020%, P: 0.034%, S: 0.029%, and the temperature was 1581℃. Comparing this to the target temperature revealed that trace amounts of each element needed to be added. This was done using ferromanganese alloy wire with 80% Mn content. The required amount of Mn element is 70800kg × (1.37% - 1.35%) = 14.16kg. If the wire feed yield is 92%, then the required amount of ferromanganese alloy wire is 14.16 ÷ 80% ÷ 92% ≈ 19.4kg. The linear density of ferromanganese alloy is 7.6 g / cm³. 3The diameter is 12mm, and the weight per meter is approximately 0.85kg. Therefore, the required wire length is 19.4÷0.85≈22.8m. The actual wire length required is 23m. After calculation, 23m of ferromanganese alloy wire is fed in using a wire feeder. After replenishment, the wire is left to stand for 2 minutes, and the steel composition and temperature are checked again. The steel composition is measured to be C: 0.23%, Si: 0.35%, Mn: 1.37%, V: 0.021%, P: 0.034%, and S: 0.029%. All composition deviations are controlled within ±0.01%, which meets the internal control requirements of HRB400E for 12-25mm specifications.

[0024] Example 2 The difference from Example 1 is that, for HRB400E steel with a diameter >25mm, the target composition of the molten steel is C: 0.22%-0.25%, Si: 0.38%-0.48%, Mn: 1.38%-1.48%, V: 0.030%-0.038%, P≤0.045%, and S≤0.045%, and the temperature of the molten steel is controlled at 1560℃-1600℃.

[0025] The implementation method of this embodiment is as follows: The difference from the implementation method in Example 1 is that the target composition of molten steel in the alloy batching calculation system is set as C: 0.23%, Si: 0.42%, Mn: 1.42%, V: 0.032%, P≤0.045%, S≤0.045%, and the target temperature is set as 1580℃. Then, the initial temperature, initial composition, target composition, element yield, and other parameters of molten steel are input into the system, and the required amount of pig iron for each element is calculated according to formula (1): ; ; ; If the denominator is negative, the Mn content of pig iron is lower than the target value. Adding pig iron will reduce the Mn content. Take infinity, no constraints. The required amount of pig iron is greater than 10,000 kg.

[0026] After screening, the minimum required amount of pig iron for each element was found to be 769 kg for element C, which was taken as the required amount of pig iron under compositional balance.

[0027] Then, the alloy batching calculation system is used to perform heat balance calculation. Preset parameters such as the specific heat capacity of molten steel, the specific heat capacity of pig iron, the initial temperature, and the target temperature are input. The maximum amount of pig iron under heat balance is calculated according to formula (2): Comparing the composition balance amount of 769 kg with the maximum heat balance amount of 737 kg, the smaller value of 737 kg is taken, which is rounded to 740 kg. 740 kg of pig iron is added to the ladle via a chute, while simultaneously 90 kg of a silicon-manganese alloy containing 65% Mn and 18% Si is added via a quantitative feeder. After standing for 3 minutes, the composition and temperature of the molten steel are measured again. The measured composition of the molten steel is: C: 0.219%, Si: 0.38%, Mn: 1.32%, V: 0.024%, P: 0.034%, S: 0.029%, the temperature is 1582℃, and the weight is 70830 kg.

[0028] The results were input again into the alloy proportioning calculation system. Considering the composition requirements for sizes >25mm, the required amount of pig iron was determined to be 210kg. Then, 120kg of pig iron was slowly added in batches to the lower part of the ladle via a chute to avoid splashing of molten steel. Simultaneously, the bottom-blowing argon system of the ladle was activated, employing a three-stage stirring pattern: weak-strong-weak. The stirring speed was 12L / min for 1 minute initially, 16L / min for 1.5 minutes in the middle stage, and 14L / min for 1 minute in the later stage, for a total of 3.5 minutes. During the stirring process, the molten steel temperature was monitored in real time using an infrared thermometer to ensure it remained stable at approximately 1580℃.

[0029] The entire process involved observing the molten steel surface with an industrial camera and monitoring the temperature with an infrared thermometer. After confirming that the pig iron was completely melted, the composition and temperature were checked again. The molten steel composition was measured to be: C: 0.228%, Si: 0.41%, Mn: 1.40%, V: 0.030%, P: 0.034%, S: 0.029%, and the temperature was 1581℃. Comparing this to the target temperature revealed that trace amounts of each element needed to be added. This was done using ferromanganese alloy wire with 80% Mn content and ferrovanadium alloy wire with 55% V content. Ferromanganese alloy wire: 70830kg × (1.42% - 1.40%) = 14.17kg. With a wire feeding yield of 92%, the required ferromanganese alloy wire is 14.17 ÷ 80% ÷ 92% ≈ 19.5kg, corresponding to a wire length of 19.5 ÷ 0.85 ≈ 22.9m. The actual wire feeding is 23m.

[0030] Ferrovanadium alloy wire: 70830kg × (0.032% - 0.030%) = 1.42kg. With a wire feeding yield of 90%, ferromanganese alloy wire is required: 1.42 ÷ 55% ÷ 90% ≈ 2.8kg. The corresponding wire length is 2.8 ÷ 0.98 ≈ 2.9m. The actual wire feeding is 3m.

[0031] 23m of ferromanganese alloy wire and 3m of ferrovanadium alloy wire were fed in using a wire feeder. After replenishment, the molten steel was allowed to stand for 2 minutes, and the composition and temperature of the molten steel were tested again. The measured composition of the molten steel was C: 0.23%, Si: 0.42%, Mn: 1.42%, V: 0.032%, P: 0.034%, and S: 0.029%. All composition deviations were controlled within ±0.01%, which meets the internal control requirements of HRB400E for specifications >25mm.

[0032] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for deoxidizing and alloying pig iron for converters, characterized in that, This includes selecting the composition of pig iron and controlling the converter smelting process, specifically including the following: Selected pig iron composition: The selected pig iron composition is: C: 3.8-4.2%, Si: 1.2-1.8%, Mn: 0.8-1.2%, V: 0.08-0.12%, P≤0.08%, S≤0.03%; Controlling the converter smelting process: Based on the steel composition, the amount of pig iron added is calculated to determine the final temperature, and the amount of scrap steel added is controlled based on the calculation results.

2. The production method for deoxidizing and alloying pig iron for converters according to claim 1, characterized in that, The specific operating steps for controlling converter smelting are as follows: S1: Measure the composition and temperature of the molten steel after converter smelting, and add a small amount of alloy material according to the composition of the molten steel to carry out steel alloying; S2: Preset the target composition and temperature of molten steel, and measure the composition and temperature of molten steel after adding alloy materials. Based on the measurement results, calculate the required amount of pig iron to be added using the alloy model calculation method. S3: Add the calculated amount of pig iron to the ladle in batches to stabilize the temperature of the molten steel; S4: After the added pig iron has completely melted, take another sample to measure the temperature, and supplement the required elements in trace amounts according to the measurement results.

3. The production method for deoxidizing and alloying pig iron for converters according to claim 2, characterized in that, In step S2, the specific steps for calculating the required amount of pig iron using the alloy model calculation method are as follows: a: Based on the component balance calculation formula, calculate the required amount of each element to meet the target component: （1） Where Ws is the initial weight of molten steel, Wpi is the amount of pig iron required to meet the target composition of the element, [i]s_initial is the initial composition of molten steel, [i]p is the pig iron composition, [i]s_target is the target composition of molten steel, and ηi is the element yield; b: After calculating the required amount of pig iron for all elements, take the minimum value as the required amount of pig iron under compositional balance. c: Based on the heat balance calculation formula, the maximum amount of pig iron that can be added under stable molten steel temperature is calculated: （2） Where Wp_max is the maximum amount of pig iron, Cp_steel is the specific heat capacity of molten steel (approximately 0.22 kcal / kg·℃), Cp_pig is the specific heat capacity of pig iron (approximately 0.15 kcal / kg·℃), T_initial is the initial temperature of molten steel, T_final is the target temperature of molten steel, T_pig is the initial temperature of pig iron (usually room temperature 25℃), T_melt is the melting temperature of pig iron (approximately 1150℃), and ΔH_melt is the latent heat of molten iron (approximately 50 kcal / kg). d: Compare the amount of pig iron under compositional equilibrium and the maximum amount of pig iron under thermal equilibrium, and take the smaller value as the final amount of pig iron added.

4. A production method for deoxidizing and alloying pig iron for converters according to claim 3, characterized in that, The target composition of the molten steel is C: 0.22%-0.25%, Si: 0.33%-0.48%, Mn: 1.33%-1.48%, V: 0.020%-0.038%, P≤0.045%, and S≤0.045%, with the molten steel temperature controlled at 1560℃-1600℃.

5. A production method for deoxidizing and alloying pig iron for converters according to claim 2, characterized in that, In step S3, the amount of pig iron added in each batch is controlled to be ≤500kg.

6. A production method for deoxidizing and alloying pig iron for converters according to claim 5, characterized in that, In step S3, argon gas is blown and stirred simultaneously when adding pig iron. The argon gas flow rate is 10-20 L / min, and the stirring time is 3-5 minutes.

7. A production method for deoxidizing and alloying pig iron for converters according to claim 2, characterized in that, In step S4, when adding the required elements in trace amounts, alloy additives are added using the wire feeding method or the powder spraying method. After the addition, the deviation of the molten steel composition is controlled within ±0.01% of the target value.

Images