Smelting method of steel for automobile agitator tank

Abstract

The invention relates to a smelting method of steel for an automobile agitator tank. The smelting method comprises the following procedures of desulfurization, vanadium extraction, converter steelmaking, LF refining furnace and continuous casting. In the smelting process, the alloy comprises the following components in percentage content: 0.06%-0.08% of C, 0.10%-0.20% of Si, 1.75%-1.85% of Mn, less than or equal to 0.015% of P, less than or equal to 0.005% of S, 0.060%-0.070% of Nb, 0.09%-0.11% of Ti, 0.020%-0.050% of ALs, less than or equal to 0.0040% of [N] and the balance of iron and other inevitable elements. According to the diversified slagging process, rapid formation of the initial slag can be accelerated, erosion of the initial slag to the converter lining can be relieved, and the service life of the converter lining is prolonged.

Description

Technical Field

[0001] The patented technology of this invention relates to a steel smelting method and process, specifically to a smelting method for steel for automobile mixing tanks. Background Art

[0002] The development of high value-added varieties is a necessary means for the future development and survival of steel enterprises. In view of the characteristics of high residual elements in molten steel during smelting of vanadium-titanium magnetite in blast furnaces, Chenggang has developed and implemented a multi-stage combined comprehensive treatment method for vanadium-containing molten iron, which has achieved effective control of S, Ti, V and other elements in the production process of automotive steel, silicon steel and IF steel, and developed steel for automotive mixing tanks (C750JJ) to ensure product production quality, give full play to its own and equipment advantages, and no longer affect the extraction of precious metals vanadium and titanium in vanadium-titanium molten iron, saving mineral resources. At the same time, the converter smelting adopts double-annular seam air-permeable brick bottom blowing gas supply and diversified slag making process, which not only strengthens the stirring force of the entire molten pool, but also effectively improves the uniformity of composition and temperature in the molten pool, and makes the carbon-oxygen reaction closer to equilibrium, avoiding overoxidation of molten steel. Stable converter re-blowing can reduce carbon-oxygen accumulation and TFe content in slag, reduce steel material consumption, and improve molten steel quality and alloy yield. Moreover, the diversified slag-making process can not only accelerate the rapid formation of initial slag, but also slow down the erosion of the initial slag on the furnace lining, thereby increasing the service life of the converter lining. Summary of the invention

[0003] The present invention provides a method for smelting steel for automobile stirring tanks in order to slow down the erosion of the furnace lining by the initial slag and increase the service life of the converter lining.

[0004] The technical solution to the above problems is:

[0005] A smelting method for steel for automobile mixing tanks comprises the following processes: desulfurization - vanadium extraction - converter - converter steelmaking - LF refining furnace - continuous casting process; the composition and percentage of each component in the smelting process are: C: 0.06-0.08%, Si: 0.10-0.20%, Mn: 1.75-1.85%, P≤0.015%, S≤0.005%, Nb: 0.060-0.070%, Ti: 0.09-0.11%, ALs: 0.020-0.050%, [N]≤0.0040%, and the remainder is iron and other inevitable elements.

[0006] Preferably, the desulfurization process: the desulfurization operation is carried out at a molten iron temperature of ≥1250°C, the clearance of the molten iron ladle is >400mm, the net weight of the molten iron is 175±5 tons / furnace, and lime and granular magnesium are compositely sprayed: the lime spraying rate ranges from 21 to 45kg / min, the granular magnesium spraying rate ranges from 7 to 15kg / min, and the mass ratio of granular magnesium to lime is 1:3. The spraying time and spraying amount are adjusted according to the sulfur content of the molten iron, and multiple slag stripping or early slag stripping are used to make the sulfur content of the molten iron meet the process requirements of S mass content ≤0.008%, thereby reducing the desulfurization time of the LF refining furnace, shortening the smelting cycle, and saving smelting costs.

[0007] Preferably, in the vanadium extraction process, the gun position is controlled in accordance with a high-low-low-high operation mode, the gun position is 1.25-1.50 m, the oxygen gun lifting amplitude is ≤0.2 m / time, the oxygen pressure is controlled at 0.70-1.20 MPa, the oxygen supply time is 4-8 min, and the terminal temperature is controlled at 1360-1420° C. The semi-steel carbon hit is 3.2-3.4%, achieving the stability of the semi-steel conditions.

[0008] Preferably, the converter steelmaking process: the converter smelting adopts double-annular seam breathable brick bottom blowing gas supply, which strengthens the stirring force of the entire molten pool, effectively improves the uniformity of the composition and temperature in the molten pool, and further approaches the carbon-oxygen reaction to balance, avoiding overoxidation of molten steel. Stable converter re-blowing can reduce carbon-oxygen accumulation and TFe content in slag, reduce steel material consumption, and improve molten steel quality and alloy yield.

[0009] Preferably, after the ladle is seated in the converter steelmaking process, argon is used to replace the gas in the ladle to effectively control nitrogen, and a diversified slag making process is adopted, and the quantitative ratio of the magnetic separation slag under the furnace is 2 to 3 tons / furnace, which increases the MnO and Al 2 O 3 and SiO 2 The self-produced steel slag surface and slag-making materials with different components can use MgO and MnO in the slag to expand the liquid phase and promote lime melting. In the early stage of blowing, the slag retention operation is used to increase the MgO ratio and reach saturation. This can not only accelerate the rapid formation of initial slag, but also slow down the erosion of the initial slag on the furnace lining.

[0010] Preferably, the converter steelmaking process: the converter end temperature is 1670-1685°C, the continuous pulling temperature is 1650-1665°C, the process smelting oxygen lance position is controlled at 1.4-1.7 meters, the oxygen pressure is 0.7-0.9Mpa, and the oxygen flow rate is 24000-36000Nm 3 / h, within 2 to 3 minutes of blowing, the oxygen flow rate is 24000Nm 3 / h. According to the flame state and the sound in the furnace, determine the slagging situation and blowing state, adjust the gun position and add cold material in time to smoothly control the blowing, control the oxygen supply time at 11-15min, stop the oxygen supply at the end and there must be more than 60 seconds of gun pressing operation before starting the gun, and the gun position is lowered to 1.3-1.4m. According to the carbon-oxygen reaction curve, carbon is pulled once, and supplementary blowing is strictly prohibited. After blowing is completed, a slide plate is used to block the slag during the steelmaking process, and slag is strictly prohibited.

[0011] Preferably, the optimal controlled mass content at the end point of the converter steelmaking process is [C]: 0.03-0.04%, [P] ≤ 0.012%, and [S] ≤ 0.010%.

[0012] Preferably, the LF refining furnace process: the argon gas flow rate is set to ≤1500NL / min, the feeding time is controlled to 2-3min, and the deoxidizer aluminum wire forging 100-200kg / furnace and the ladle modifier 150-300kg / furnace are added first, and then the lime is added; before the unbroken slag furnace is heated for the first time, 600-1000kg / furnace of lime is added, and the heating process can be added in batches, each time ≤200kg is added. After the feeding is completed, the material is fully stirred and melted, and it is confirmed that there is no material block exceeding 0.04㎡, and the argon gas flow rate is adjusted to 150-300NL / min for heating treatment. In the early stage of electrode heating, long arc heating is used for 2-3min to melt the slag, and short arc heating is used in the later stage. The arc + foam slag operation heats up quickly. After the first heating is completed, the argon is adjusted to 800-1200NL / min. Deoxidation and desulfurization operations are carried out for 3-5 minutes. The degree of deoxidation is determined according to the sticky slag state and color, and the amount of deoxidizer aluminum particles and lime added is adjusted in time to make the sticky slag thickness 1.5-3mm and the slag fluidity good. During the strong stirring process of argon, deep deoxidation is carried out to form white slag. The argon is adjusted to 150-300NL / min for temperature measurement. Depending on the measured temperature, whether to conduct a secondary heating and compensation temperature to the first furnace temperature of 1585-1595℃ and the continuous furnace temperature of 1565-1575℃, the chemical sample composition compensation is carried out.

[0013] Preferably, after the LF refining furnace process is completed, the chemical composition of the samples meets the quality requirements, C: 0.06-0.08%, Si: 0.10-0.20%, Mn: 1.75-1.85%, P≤0.015%, S≤0.005%, Nb: 0.060-0.070%, Ti: 0.09-0.11%, ALs: 0.020-0.050%, [N]≤0.0040%.

[0014] Preferably, in the early stage of electrode heating in the LF refining furnace process, a long arc with a voltage of six levels is used, and in the later stage, a short arc with a voltage of four levels is used.

[0015] The beneficial effects of the present invention are:

[0016] The composite spray desulfurization of the present invention makes the sulfur content of molten iron meet the process requirements, relieves the desulfurization time of LF refining furnace, shortens the smelting cycle, and saves smelting costs. The converter smelting adopts double-annular seam air-permeable brick bottom blowing gas supply and diversified slag making process, which not only strengthens the stirring force of the entire molten pool, but also effectively improves the uniformity of the composition and temperature in the molten pool, and the carbon-oxygen reaction is closer to equilibrium, avoiding the overoxidation of molten steel. Stable converter re-blowing can reduce carbon-oxygen accumulation and TFe content of slag, reduce steel material consumption, and improve molten steel quality and alloy yield. In addition, the diversified slag making process can not only accelerate the rapid formation of initial slag, but also slow down the erosion of the initial slag on the furnace lining, thereby increasing the service life of the converter lining. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is further described in detail below in conjunction with embodiments.

[0018] Examples 1-6

[0019] A smelting method for steel for automobile mixing tanks, characterized in that it includes the following processes: desulfurization - vanadium extraction - converter - converter steelmaking - LF refining furnace - continuous casting process; the details are as follows:

[0020] (1) Desulfurization process: Desulfurization is carried out when the temperature of molten iron is ≥1250℃, the clearance of the molten iron ladle is>400mm, the net weight of the molten iron is 175±5 tons, and lime and granular magnesium are sprayed together: the lime spraying rate ranges from 21 to 45kg / min, the granular magnesium spraying rate ranges from 7 to 15kg / min, and the mass ratio of granular magnesium to lime is 1:3. The spraying time and spraying amount are adjusted according to the sulfur content of the molten iron. Multiple slag removal or early slag removal is used to make the sulfur content of the molten iron meet the process requirements of S mass content ≤0.008%, thereby reducing the desulfurization time of the LF refining furnace, shortening the smelting cycle, and saving smelting costs.

[0021] Table 1 Desulfurization process parameters of Examples 1-6

[0022]

[0023] (2) Vanadium extraction process: The gun position is controlled in accordance with the high-low-low-high operation mode, the gun position is 1.25-1.50m, the oxygen gun lifting amplitude is ≤0.2m / time, the oxygen pressure is controlled at 0.70-1.20Mpa, the oxygen supply time is 4-8min, and the terminal temperature is controlled at 1360-1420℃. The semi-steel carbon hit is 3.2-3.4%, achieving the stability of the semi-steel conditions.

[0024] Table 2 Parameters of vanadium extraction process in Examples 1-6

[0025] Example Gun position / m Oxygen pressure / Mpa Oxygen supply time / min End point temperature / ℃ Semi-steel carbon content / % 1 1.25 0.70 4 1360 3.2 2 1.30 0.80 5 1380 3.3 3 1.38 0.90 6 1400 3.3 4 1.42 1.00 7 1410 3.4 5 1.48 1.10 8 1390 3.3 6 1.50 1.20 8 1420 3.4

[0026] (3) Converter steelmaking process: The converter smelting adopts double-annular seam air-permeable brick bottom blowing to supply air, which strengthens the stirring force of the entire molten pool, effectively improves the uniformity of the composition and temperature in the molten pool, and further approaches the balance of carbon-oxygen reaction, avoiding overoxidation of molten steel. Stable converter re-blowing can reduce carbon-oxygen accumulation and TFe content in slag, reduce steel material consumption, and improve molten steel quality and alloy yield.

[0027] After the ladle is seated, argon gas is used to replace the gas in the ladle to effectively control nitrogen. A diversified slag making process is adopted, and 2 to 3 tons of magnetic separation slag is quantitatively mixed per furnace to increase MnO and Al 2 O 3 and SiO 2 The self-produced steel slag surface and slag-making materials with different components can use MgO and MnO in the slag to expand the liquid phase and promote lime melting. In the early stage of blowing, the slag retention operation is used to increase the MgO ratio and reach saturation. This can not only accelerate the rapid formation of initial slag, but also slow down the erosion of the initial slag on the furnace lining.

[0028] The end point temperature is 1670~1685℃, the continuous pulling temperature is 1650~1665℃, the oxygen lance position of the process smelting is controlled at 1.4~1.7 meters, the oxygen pressure is 0.7~0.9Mpa, and the oxygen flow rate is 24000~36000Nm 3 / h, within 2 to 3 minutes of blowing, the oxygen flow rate is 24000Nm 3 / h. According to the flame state and the sound in the furnace, determine the slagging situation and blowing state, adjust the gun position and add cold material in time to smoothly control the blowing, control the oxygen supply time at 11-15min, stop the oxygen supply at the end and there must be more than 60 seconds of gun pressing operation before starting the gun, and the gun position is lowered to 1.3-1.4m. According to the carbon-oxygen reaction curve, carbon is pulled once, and supplementary blowing is strictly prohibited. After blowing is completed, a slide plate is used to block the slag during the steelmaking process, and slag is strictly prohibited.

[0029] The optimal controlled mass content at the end point of converter steelmaking process is [C]: 0.03-0.04%, [P] ≤ 0.012%, [S] ≤ 0.010%.

[0030] Table 3 Converter process parameters of Examples 1-6

[0031]

[0032] (4) LF refining furnace process: the argon gas flow rate is set to ≤1500NL / min, the feeding time is controlled to 2-3min, first add 100-200kg of deoxidizer aluminum wire forging and 150-300kg of ladle modifier, and then add lime; before heating the unslag furnace, add 600-1000kg of lime, and add it in batches during the heating process, each time adding ≤200kg. After the feeding is completed, stir and melt thoroughly to confirm that there is no material block exceeding 0.04㎡, adjust the argon gas flow rate to 150-300NL / min, and carry out heating treatment. In the early stage of electrode heating, long arc heating is used for 2-3min to melt the slag, and short arc + foam is used in the later stage. The slag is heated up quickly. After the first heating, the argon is adjusted to 800-1200NL / min. Deoxidation and desulfurization operations are carried out for 3-5 minutes. The degree of deoxidation is determined according to the sticky slag state and color. The amount of deoxidizer aluminum particles and lime added is adjusted in time to make the sticky slag thickness 1.5-3mm and the slag fluidity good. During the strong stirring process of argon, deep deoxidation is carried out to form white slag. The argon is adjusted to 150-300NL / min for temperature measurement. Depending on the measured temperature, whether to conduct a secondary heating and compensation temperature to the first furnace temperature of 1585-1595℃ and the continuous furnace temperature of 1565-1575℃, the chemical sample composition compensation is carried out. The chemical composition of the samples meets the quality requirements, C: 0.06~0.08%, Si: 0.10~0.20%, Mn: 1.75~1.85%, P≤0.015%, S≤0.005%, Nb: 0.060~0.070%, Ti: 0.09~0.11%, ALs: 0.020~0.050%, [N]≤0.0040.

[0033] Table 4 Example 1-6LF refining furnace process parameters

[0034]

[0035] Table 5 Chemical composition and mass percentage of molten steel in Examples 1-6 (%)

[0036] Example C Si Mn P S Nb Ti ALs N 1 0.06 0.10 1.75 0.015 0.005 0.060 0.090 0.020 0.0040 2 0.07 0.12 1.78 0.012 0.003 0.062 0.095 0.033 0.0038 3 0.08 0.15 1.80 0.010 0.002 0.065 0.100 0.036 0.0036 4 0.07 0.16 1.81 0.009 0.003 0.067 0.098 0.040 0.0035 5 0.06 0.18 1.83 0.011 0.002 0.068 0.110 0.045 0.0033 6 0.08 0.20 1.85 0.013 0.003 0.070 0.099 0.050 0.0030

[0037] In Table 5, the remainder is Fe and unavoidable impurities.

[0038] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments with equivalent changes without departing from the scope of the technical solution of the present invention.

Claims

1. A method for smelting steel for automobile mixing tanks, characterized in that: The process includes: desulfurization - vanadium extraction - converter steelmaking - LF refining furnace - continuous casting process; the composition and percentage of each component in the smelting process are: C: 0.06-0.08%, Si: 0.10-0.20%, Mn: 1.75-1.85%, P≤0.015%, S≤0.005%, Nb: 0.060-0.070%, Ti: 0.09-0.11%, ALs: 0.020-0.050%, [N]≤0.0040%, and the remainder is iron and other inevitable elements.

2. The smelting method of a steel for automobile mixing tank according to claim 1, characterized in that: Desulfurization process: Desulfurization operation is carried out when the molten iron temperature is ≥1250℃, the clearance of the molten iron ladle is>400mm, the net weight of the molten iron is 175±5 tons / furnace, and the composite injection of lime and granular magnesium is adopted: the injection rate of lime is in the range of 21~45kg / min, the injection rate of granular magnesium is in the range of 7~15kg / min, and the mass ratio of granular magnesium to lime is 1:

3. The injection time and injection amount are adjusted according to the sulfur content of the molten iron. Multiple slag removal or early slag removal is adopted to make the sulfur content of the molten iron meet the process requirements of S mass content ≤0.008%.

3. The smelting method for steel for automobile mixing tank according to claim 1, characterized in that: Vanadium extraction process: The gun position is controlled in the high-low-low-high operation mode, the gun position is 1.25-1.50m, the oxygen gun lifting amplitude is ≤0.2m / time, the oxygen pressure is controlled at 0.70-1.20Mpa, the oxygen supply time is 4-8min, and the terminal temperature is controlled at 1360-1420℃. The carbon hit of semi-steel is 3.2-3.4%.

4. The smelting method of a steel for automobile mixing tank according to claim 1, characterized in that: Converter steelmaking process: Converter smelting uses double annular seam breathable bricks to blow air from the bottom to carry out carbon-oxygen reaction.

5. The smelting method for steel for automobile mixing tank according to claim 4, characterized in that: The converter steelmaking process also includes: after the ladle is seated, argon is used to replace the gas in the ladle to effectively control nitrogen, a diversified slag-making process is adopted, 2 to 3 tons of magnetic separation slag is quantitatively proportioned per furnace, self-produced slag surface and slag-making materials with increased MnO, Al2O3 and SiO2 components are used, and slag retention operation is used in the early stage of blowing to increase the MgO ratio so that the MgO content reaches saturation.

6. The smelting method for steel for automobile mixing tank according to claim 4, characterized in that: Converter steelmaking process: converter end temperature 1670 ~ 1685 ℃, continuous pulling temperature 1650 ~ 1665 ℃, process smelting oxygen lance position controlled at 1.4 ~ 1.7 meters, oxygen pressure 0.7 ~ 0.9Mpa, oxygen flow 24000 ~ 36000Nm 3 / h, within 2 to 3 minutes of blowing, the oxygen flow rate is 24000Nm 3 / h; According to the flame state and the sound in the furnace, determine the slagging situation and blowing state, adjust the gun position and add cold material in time to smoothly control the blowing, control the oxygen supply time at 11-15min, stop the oxygen supply at the end and there must be more than 60 seconds of gun pressing operation before starting the gun, the gun position is lowered to 1.3-1.4m, pull carbon once according to the carbon-oxygen reaction curve, and it is strictly forbidden to blow again. After blowing, use a slide plate to block the slag during the steelmaking process, and it is strictly forbidden to drop slag.

7. The smelting method for steel for automobile mixing tank according to claim 6, characterized in that: The optimal controlled mass content at the end point of converter steelmaking process is [C]: 0.03-0.04%, [P] ≤ 0.012%, [S] ≤ 0.010%.

8. The smelting method for steel for automobile mixing tank according to claim 1, characterized in that: LF refining furnace process: the argon gas flow rate is set to ≤1500NL / min, the feeding time is controlled to 2-3min, first add 100-200kg / furnace of deoxidizer aluminum wire forging and 150-300kg / furnace of ladle modifier, and then add lime; before heating the furnace without slag folding, add 600-1000kg / furnace of lime, and the heating process can be added in batches with each addition of ≤200kg. After the feeding is completed, stir and melt thoroughly to confirm that there is no material block exceeding 0.04㎡, adjust the argon gas flow rate to 150-300NL / min, and carry out heating treatment. In the early stage of electrode heating, long arc heating is used for 2-3min to melt the slag, and short arc + The foam slag is heated up quickly during operation. After one heating, the argon gas is adjusted to 800-1200NL / min. Deoxidation and desulfurization operations are carried out for 3-5 minutes. The degree of deoxidation is determined according to the sticky slag state and color. The amount of deoxidizer aluminum particles and lime added is adjusted in time to make the sticky slag thickness 1.5-3mm and the slag fluidity good. During the strong stirring process of argon gas, deep deoxidation is carried out to form white slag. The argon gas is adjusted to 150-300NL / min for temperature measurement. Depending on the measured temperature, whether to conduct a secondary heating and compensation temperature to the first furnace temperature of 1585-1595℃ and the continuous furnace temperature of 1565-1575℃, the chemical sample composition compensation is carried out.

9. The method for smelting steel for automobile mixing tank according to claim 8, characterized in that: After the LF refining furnace process is completed, the chemical composition of the samples meets the mass percentage requirements, C: 0.06-0.08%, Si: 0.10-0.20%, Mn: 1.75-1.85%, P≤0.015%, S≤0.005%, Nb: 0.060-0.070%, Ti: 0.09-0.11%, ALs: 0.020-0.050%, [N]≤0.0040%.

10. The method for smelting steel for automobile mixing tank according to claim 8, characterized in that: In the early stage of electrode heating in the LF refining furnace process, a long arc with a voltage of six levels is used, and in the later stage, a short arc with a voltage of four levels is used.

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