CN102230051B - Method for controlling nitrogen content in steel by semi-steel smelting - Google Patents
Method for controlling nitrogen content in steel by semi-steel smelting Download PDFInfo
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Abstract
The invention discloses a method for controlling nitrogen content in steel by semi-steel smelting. According to the invention, the method for controlling nitrogen content in steel by semi-steel smelting comprises the following steps of: performing oxygen top blowing by using a converter, performing slag-modifying treatment before tapping, and blocking the slag and tapping. In addition, according to the requirements steel on nitrogen content, different bottom-blowing modes are adopted in the oxygen top blowing process by converter, a foaming agent is added at the last stage of blowing, argon gas is blown to ladles 1 to 3 minutes before tapping, and the soft argon blowing operation is performed on ladles during the tapping step. By adoption of the method provided by the invention, the nitrogen content in steel at the converter end-point can be controlled to be within 11 ppm and the nitrogen increase can be controlled to be between 1ppm to 3 ppm during the tapping step. The method provided by the invention can effectively reduce the nitrogen content at the converter end-point and the nitrogen increase in the tapping step, thereby providing a technical support for the production of low-nitrogen steel and ultra-low nitrogen steel.
Description
Technical field
The present invention relates to the ferrous metallurgy field, particularly a kind of half steel is smelted the method for control nitrogen in steel content.
Background technology
Nitrogen content in the steel has certain influence to the performance of steel, and for most of steel grades, the nitrogen element can reduce performances such as toughness and the welding of steel, so should as far as possible it be removed from steel.Usually, in the hot metal pretreatment stage, can from molten iron, remove the nitrogen about 60% through adding the denitrfying agent of forming by titanium slag and yellow soda ash, but the use of yellow soda ash can bring problems such as equipment corrosion, so there be limited evidence currently of adopts this method to come denitrogenation.In the secondary refining stage, the LF refining process makes molten steel nitrogen pick-up owing to decomposing at arc region generation nitrogen, and RH vacuum refinement process can be sloughed a part of nitrogen in the molten steel, but when the massfraction of nitrogen in steel was lower than 0.004%, denitrification effect was not remarkable.Therefore, when smelting the low nitrogen steel kind, the process of bessemerizing is the most important link of control nitrogen in steel content.
Article " research of IF steel nitrogen content control techniques " (" iron and steel "; 2010 the 7th phases) method of the nitrogen content that can reduce converter smelting endpoint is discussed; Wherein, go into the stove hot metal ratio through improving, smelting process control is returned dried; Smelting endpoint reduces the methods such as number of times and time of re-blowing can reduce the nitrogen content of converter smelting endpoint, thus produce nitrogen content at 20ppm with interior IF steel.But this method technology is more loaded down with trivial details, and does not consider the influence of converter bottom blowing to nitrogen in steel content.Publication number is that the one Chinese patent application of CN101469356A discloses a kind of method for making steel that utilizes converter tapping feeble deoxidization to reduce nitrogen in steel content, and said method is controlled at its sulphur content below 0.004% through with after the hot metal pretreatment; Carry out the argon gas soft blow; Stirred 5～10 minutes pushing off the slag tapping, the not killing of tapping with argon gas at converter terminal; Realized the nitrogen content in the steel being controlled between 20～30ppm not adding new installation or transforming under the situation of used equipment.But this patented claim mainly is that control is not set forth to the smelting process nitrogen content at tapping process control nitrogen in steel content.
Semi-steel making is because the general molten iron low (3.4%～4.0%) of its carbonaceous amount percentage ratio; Silicon, manganese heating slagging constituent content are vestige in the half steel; Therefore half steel is smelted and is had that acid slagging material is few in the converting process, the slag system constituent element is single and characteristics such as shortage of heat; This makes semi-steel making more difficult more than molten iron-steelmaking, can know according to the solubleness formula of nitrogen in steel content simultaneously: w
[N]=0.044-0.01w
[C]-0.025w
[Mn]-0.003w
[Si]-0.0043w
[P]-0.001w
[S]+ 0.0069w
[Cr]+ 0.013w
[V]-0.001w
[Ni]-0.01w
[Al]+ 0.1w
[Ti]+ 0.0015w
[Mo]+ 0.0102w
[Nb]-0.0004w
[Cu], w
[*]Refer to the percentage composition of elements corresponding in steel, as: the carbon content in the steel is 0.09%, then w
[C]=0.09.Because contain V, Ti in the steel, and Si and Mn content are few, so can increase the theoretical dissolution degree of nitrogen content in the molten steel.Nitrogen content when therefore, half steel is smelted in the control molten steel is more difficult more than the nitrogen content in the control molten iron.
Summary of the invention
For overcoming the problem and shortage that above-mentioned prior art exists; The present invention is through adopting different bottom blowing patterns; And add whipping agent control nitrogen pick-up latter stage in blowing, and avoid re-blowing, carry out residue adjustment before the tapping and handle; And the pushing off the slag tapping, thereby be controlled at the method for controlling nitrogen in steel content in the half steel smelting process.
The invention provides a kind of half steel and smelt the method for control nitrogen in steel content, residue adjustment was handled before said method comprised converter oxygen top blown, tapping, the pushing off the slag tapping; Wherein, According to the requirement of steel grade, in converter oxygen top blown process, adopt different bottom blowing patterns, and add whipping agent latter stage in blowing to nitrogen content; 1～3min carries out BOTTOM ARGON BLOWING to ladle in advance before tapping, and tapping process carries out the operation of soft blow argon to ladle.
According to the method for the invention, when finished product nitrogen in steel content is 40ppm～70ppm, be employed in bottom blowing nitrogen in oxygen top blown 8～10min, then the bottom blowing pattern that finishes up to tapping of blowing argon gas; The intensity of said bottom blowing nitrogen is 0.016～0.089m
3/ (mint), the intensity of argon bottom-blowing is 0.026～0.062m
3/ (mint).
According to the method for the invention, when finished product nitrogen in steel content during less than 40ppm, adopt the oxygen top blown process bottom blowing pattern of argon bottom-blowing simultaneously, the intensity of said argon bottom-blowing is 0.041～0.077m
3/ (mint).
The intensity of according to the method for the invention, in the tapping process ladle being carried out Argon is that the intensity of Argon is 0.003～0.007m
3/ (mint), BOTTOM ARGON BLOWING pressure is 0.6～1.3MPa.
According to the method for the invention, the component of whipping agent is: the FeO of 28wt%～45wt%, the Fe of 7wt%～10wt%
2O
3, the CaO of 18wt%～22wt%, the SiO of 6wt%～9wt%
2, the MgO of 8wt%～11wt%, the C of 3wt%～5wt%, surplus is an impurity; The add-on of whipping agent is 3～7Kg/t
Steel
In the present invention, 1～3min carries out Argon to ladle in advance before tapping, and tapping process carries out the operation of soft blow argon to ladle, and tapping process carries out preliminary dexidation to molten steel.The present invention can be controlled at converter terminal nitrogen in steel content in the 11ppm, and the tapping process nitrogen increased amount is controlled in 1～3ppm.Method of the present invention can reduce converter terminal nitrogen content and the nitrogen increased amount that reduces tapping process effectively, for the production of low nitrogen steel and ultra low nitrogen steel provides technical support, has good popularization and application prospect.
Embodiment
The converter smelting denitrogenation mainly is that this moment, reaction between carbon and oxygen produced a large amount of CO in reaction between carbon and oxygen the fiercest mid-term, because nitrogen partial pressure is very low in the bubble, the dissolved gases, bubble just is equivalent to the effect of little Vakuumkammer in molten steel.Therefore, [N] atom in the molten steel just can spontaneously get into and form N in the bubble
2Molecule, and discharge from molten steel with the CO bubble.And molten steel nitrogen pick-up mainly occurs in latter stage, and the interior reaction between carbon and oxygen of stove this moment slows down, and the CO amount that reaction between carbon and oxygen produces is few, and oxygen jet blows slag open, and molten steel is exposed in the air, thereby makes molten steel inhale nitrogen.
The method of control nitrogen in steel content when therefore, the invention provides a kind of converter smelting half steel.Here, it is pointed out that half steel is that the silicon in the molten steel, manganese element were almost completely oxidized after the vanadium-bearing hot metal process was extracted vanadium slag, a part that carbon is also oxidized, silicon, manganese content are a kind of metal liquid of vestige.In the present invention, according to the requirement of steel grade, in converter oxygen top blown process, adopt different bottom blowing gas patterns to nitrogen content; And (can judge blowing latter stage according to duration of blast in blowing latter stage; When being generally blowing 9-14min), add whipping agent and also control blowing nitrogen pick-up in latter stage, thereby avoided re-blowing to promote denitrogenation; Can before tapping, carry out residue adjustment and handle, and the pushing off the slag tapping.According to the present invention, (for example, before tapping in 1～3min) carried out BOTTOM ARGON BLOWING to ladle before the tapping prerequisite, and tapping process carries out the operation of soft blow argon to ladle.According to the method for the invention, can the converter terminal nitrogen content be controlled in the 11ppm, the tapping process nitrogen increased amount is controlled at 1ppm～3ppm.
Can steel grade be divided into low nitrogen steel and ultra low nitrogen steel according to steel grade to the requirement of nitrogen content, wherein, low nitrogen steel requires that nitrogen content is 40ppm～70ppm in the Finished Steel, and nitrogen content is less than 40ppm in the ultra low nitrogen steel requirement Finished Steel.
According to the method for the invention, for low nitrogen steel, that is, when finished product nitrogen in steel content is 40ppm～70ppm, be employed in bottom blowing nitrogen in oxygen top blown 8min～10min, then the bottom blowing pattern that finishes up to tapping of blowing argon gas; The intensity of said bottom blowing nitrogen is 0.016～0.089m
3/ (mint), the intensity of argon bottom-blowing is 0.026～0.062m
3/ (mint).Specifically, when smelting low nitrogen steel, smelting is the vigorous oxidation of carbon in earlier stage, and violent reaction makes the nitrogen in the molten steel to discharge in the stove with the gas that reaction produces in the stove, thus adopt bottom blowing nitrogen, and do not adopt argon bottom-blowing, can reduce ton smelting steel cost like this.And smelting the later stage, and reaction in furnace is mild relatively, and the bubble that reaction produces reduces, and denitrification effect is very poor, and the minimizing of furnace pressure can make and contact with molten steel in the air admission stove, causes molten steel to inhale nitrogen.Can make molten steel seriously inhale nitrogen if nitrogen is still adopted in bottom blowing, influence the converter denitrification effect.
According to the method for the invention, for ultra low nitrogen steel, that is, when finished product nitrogen in steel content during less than 40ppm, adopt the oxygen top blown process bottom blowing pattern of argon bottom-blowing simultaneously, the intensity of said argon bottom-blowing is 0.041～0.077m
3/ (mint).With the principle of smelting low nitrogen steel much at one, difference is, the air supply intensity of later stage argon bottom-blowing increases to some extent when smelting ultra low nitrogen steel, helps smelting the later stage denitrogenation like this.High-intensity argon bottom-blowing of later stage can make the nitrogen in the stove be excluded along with the come-up of BOTTOM ARGON BLOWING bubble, strengthens the denitrification effect of smelting the later stage.
The intensity of according to the method for the invention, in the tapping process ladle being carried out Argon is 0.003～0.007m
3/ (mint), BOTTOM ARGON BLOWING pressure is 0.6～1.3MPa.
In order to have solved the technical problem of converter smelting molten steel nitrogen pick-up in latter stage, the present invention controls the nitrogen content in the steel through adding whipping agent in the later stage, thereby has avoided re-blowing, if re-blow oxygen, can the top of the slag be blown open, makes the serious nitrogen pick-up of molten steel.Oxygen is re-blow and is meant when smelting soon near terminal point, stop oxygen blast and temperature and the carbon content of molten steel measured, if carbon and temperature do not reach tap requirement to re-blow oxygen so that the carbon temperature meet the demands.According to the present invention, the component of whipping agent is: the FeO of 28wt%～45wt%, the Fe of 7wt%～10wt%
2O
3, the CaO of 18wt%～22wt%, the SiO of 6wt%～9wt%
2, the MgO of 8wt%～11wt%, other impurity of the C of 3wt%～5wt% and 13wt%～15wt%.Smelting reaction between carbon and oxygen in latter stage slows down, and the CO amount that reaction produces is few, and oxygen jet is opened the slag top blast, and molten steel is exposed in the air, makes molten steel suction nitrogen easily.In the whipping agent owing to contain higher FeO and Fe
2O
3, help reducing slag viscosity, slag fluidity is strengthened, and fully molten steel surface is covered, prevent that molten steel from inhaling nitrogen from air.Add in the stove of back and produce a large amount of CO bubbles, in the time of the discharge of CO bubble nitrogen in the molten steel is sloughed, the effect of secluding air was played in the slag foaming when simultaneously a large amount of CO bubbles was discharged, and can prevent that the later stage molten steel from inhaling nitrogen from air.Therefore, adding whipping agent latter stage in blowing can denitrogenation and prevent nitrogen pick-up in latter stage.
According to the present invention, residue adjustment is handled and promptly in converter, is added slag supplying agent, and adding slag supplying agent in the converter of tapping forward direction is a kind of mode of converter current residue adjustment, and main purpose is to prevent slag under the tapping process with the multiviscosisty slag.
According to the present invention, the preceding 1～3min that taps is in advance to steel ladle bottom argon blowing, and purpose is to remove the air in the ladle, prevents that airborne nitrogen is dissolved in the molten steel, reduces tapping process nitrogen pick-up.
According to the present invention, tapping process carries out soft blow argon operation to ladle, and promptly the ladle bottom air feed adopts less relatively argon flow amount under guaranteeing the prerequisite of the stirring action of molten steel, and not exposing in air with molten steel is standard.
According to the capacity of converter the gas permeable brick of different quantities is set in the converter bottom, realizes the bottom blowing of converter through gas permeable brick.
Embodiment 1:
With the half steel after the vanadium extraction is that raw material is smelted gapless atomic steel (IF steel), and this steel grade requires nitrogen in steel content≤25ppm.
Half steel after the vanadium extraction is after hot metal pretreatment, and half steel directly is blended into converter and smelts, and the converter nominal capacity is 120t.Going into stove half steel weight is 138.26t, and temperature is 1356 ℃, and carbon content is 3.76%, and sulphur content is 0.005%.Through check and analysis, going into stove half steel nitrogen content is 40ppm.The beginning oxygen blast was smelted after half steel was blended into converter, and the omnidistance argon pattern that supplies is adopted in converter bottom blowing this moment: the converter bottom is four blocks of gas permeable bricks, and beginning to the single brick gas supply flow of blowing 11min from oxygen blast is 50Nm
3/ h, total air supply intensity is 0.026m
3/ (mint); The single brick gas supply flow of 9min～13min is 80Nm for supplying the argon flow
3/ h, total air supply intensity is 0.041m
3/ (mint); Supplying the argon flow behind the 13min is 120Nm
3/ h, total air supply intensity is 0.062m
3/ (mint).
When be 12min tap to tap time, in converter, add whipping agent 3Kg/t
Steel, smelt once success, do not re-blow.The component of said whipping agent is: the FeO of 28wt%, the Fe of 10wt%
2O
3, the CaO of 22wt%, the SiO of 9wt%
2, the MgO of 11wt%, the C of 5wt%, surplus is a unavoidable impurities.
Add slag supplying agent adjustment slag viscosity before the tapping, 2min is in advance to ladle argon-blown before the tapping, and the intensity that ladle carries out Argon is 0.003m
3/ (mint), BOTTOM ARGON BLOWING pressure is 0.6MPa, tapping later stage pushing off the slag tapping reduces the quantity of slag under the tapping process, tapping process soft blow argon.
Get in the converter one of steel appearance before the tapping, get in the ladle one of steel appearance after the tapping.Through check analysis, nitrogen content is 9.2ppm in the converter terminal molten steel, and nitrogen content is 12.2ppm in the ladle, tapping process nitrogen pick-up 3ppm.
Comparative examples 1:
Except do not add whipping agent latter stage in blowing with not in advance to ladle argon-blown, adopt with embodiment 1 in the half steel of the identical method of method after with vanadium extraction be raw material smelting IF steel.Nitrogen content is 15.2ppm in the converter terminal molten steel, and the molten steel nitrogen content is 21.7ppm in the ladle, tapping process nitrogen pick-up 6.5ppm.
To compare according to embodiments of the invention 1 and comparative examples 1; Can know; The converter terminal nitrogen content that obtains according to the method for comparative examples 1 wants beguine to exceed 6ppm according to the converter terminal nitrogen content that the method for embodiments of the invention 1 obtains, and does not want beguine in advance the method tapping process molten steel nitrogen pick-up of ladle argon-blown to be exceeded 3.5ppm according to the method for embodiments of the invention 1 to ladle argon-blown in advance during according to the method tapping of comparative examples 1.
Embodiment 2:
With the half steel after the vanadium extraction is that raw material is smelted 50PW800L steel, this steel grade finished product internally controlling requirement nitrogen in steel content≤45ppm.
Half steel after the vanadium extraction directly is blended into converter and smelts after hot metal pretreatment, the converter nominal capacity is 120t.Going into stove half steel carbon content is 3.52%, and sulphur content is 0.006%, and half steel weight is 137.66t, and temperature is 1369 ℃, and through check and analysis, going into stove half steel nitrogen content is 43ppm, and half steel begins oxygen blast after being blended into converter.Converter bottom blowing this moment is adopted and is supplied early stage supply the argon pattern in nitrogen later stage, and the converter bottom is provided with four blocks of gas permeable bricks, and blowing single brick nitrogen flow in early stage is 80Nm
3/ h, total air supply intensity is 0.041m
3/ (mint), the single brick gas supply flow of 9min～13min is 120Nm for supplying the argon flow
3/ h, total air supply intensity is 0.062m
3/ (mint), supplying the argon flow behind the 13min is 150Nm
3/ h, total air supply intensity is 0.077m
3/ (mint).
When be 12min tap to tap time, in converter, add whipping agent 4.5Kg/t
Steel, smelt once success, do not re-blow.The component of said whipping agent is: the FeO of 45wt%, the Fe of 7wt%
2O
3, the CaO of 18wt%, the SiO of 6wt%
2, the MgO of 8wt%, the C of 3wt%, surplus is a unavoidable impurities.
To adding slag supplying agent adjustment slag viscosity, 3min is in advance to ladle argon-blown before the tapping before the tapping, and the intensity that ladle carries out Argon is 0.007m
3/ (mint), BOTTOM ARGON BLOWING pressure is 1.5MPa, tapping later stage pushing off the slag tapping reduces the quantity of slag under the tapping process, tapping process soft blow argon.
Get in the converter one of steel appearance before the tapping, get in the ladle one of steel appearance after the tapping, through check analysis, nitrogen content is 10.5ppm in the converter terminal molten steel, and nitrogen content is 12.8ppm in the ladle, tapping process nitrogen pick-up 2.3ppm.
Comparative examples 2:
Except do not add whipping agent latter stage in blowing with not in advance to ladle argon-blown, adopt with embodiment 2 in the half steel of the identical method of method after with vanadium extraction be raw material smelting 50PW800L steel.Nitrogen content is 15.6ppm in the converter terminal molten steel, and the molten steel nitrogen content is 20.8ppm in the ladle, tapping process nitrogen pick-up 5.2ppm.
To compare according to embodiments of the invention 2 and comparative examples 2; Can know; The converter terminal nitrogen content that obtains according to the method for comparative examples 2 wants beguine to exceed 5.1ppm according to the converter terminal nitrogen content that the method for embodiments of the invention 2 obtains, and does not want beguine in advance the method tapping process molten steel nitrogen pick-up of ladle argon-blown to be exceeded 2.9ppm according to the method for embodiments of the invention 2 to ladle argon-blown in advance during according to the method tapping of comparative examples 2.
Embodiment 3:
With the half steel after the vanadium extraction is the raw material smelting heavy rail steel, this steel grade finished product internally controlling requirement nitrogen in steel content≤60ppm.
Half steel after the vanadium extraction directly is blended into converter and smelts after hot metal pretreatment, the converter nominal capacity is 120t.Going into stove half steel carbon content is 3.35%, and sulphur content is 0.003%, and half steel weight is 136.82t, and temperature is 1368 ℃, and through check and analysis, going into stove half steel nitrogen content is 39ppm, and half steel begins oxygen blast after being blended into converter.Converter bottom blowing this moment is adopted and supplied early stage supply the argon pattern in nitrogen later stage: the converter bottom is provided with six blocks of gas permeable bricks, and blowing single brick nitrogen flow in early stage is 30Nm
3/ h, total air supply intensity is 0.023m
3/ (mint), the single brick gas supply flow of 9min～11min is 50Nm for supplying the argon flow
3/ h, total air supply intensity is 0.037m
3/ (mint), supplying the argon flow behind the 11min is 80Nm
3/ h, total air supply intensity is 0.060m
3/ (mint).
When be 10min tap to tap time, in converter, add whipping agent 6Kg/t
Steel, smelt once success, do not re-blow.The component of said whipping agent is: the FeO of 40wt%, the Fe of 8wt%
2O
3, the CaO of 20wt%, the SiO of 6wt%
2, the MgO of 9wt%, the C of 4wt%, surplus is a unavoidable impurities.
To adding slag supplying agent adjustment slag viscosity, 1min is in advance to ladle argon-blown before the tapping before the tapping, and the intensity that ladle carries out Argon is 0.004m
3/ (mint), BOTTOM ARGON BLOWING pressure is 0.8MPa, tapping later stage pushing off the slag tapping reduces the quantity of slag under the tapping process, tapping process soft blow argon.
Get in the converter one of steel appearance before the tapping, get in the ladle one of steel appearance after the tapping, through check analysis, nitrogen content is 10.8ppm in the converter terminal molten steel, and steel appearance nitrogen content is 11.8ppm in the ladle, tapping process nitrogen pick-up 1ppm.
Comparative examples 3:
Except do not add whipping agent latter stage in blowing with not in advance to ladle argon-blown, the half steel of the employing method identical with method among the embodiment 3 after with vanadium extraction is the raw material smelting heavy rail steel.Nitrogen content is 15.7ppm in the converter terminal molten steel, and the molten steel nitrogen content is 20.6ppm in the ladle, tapping process nitrogen pick-up 4.9ppm.
To compare according to embodiments of the invention 3 and comparative examples 3; Can know; The converter terminal nitrogen content that obtains according to the method for comparative examples 3 wants beguine to exceed 4.9ppm according to the converter terminal nitrogen content that the method for embodiments of the invention 3 obtains, and does not want beguine in advance the method tapping process molten steel nitrogen pick-up of ladle argon-blown to be exceeded 3.9ppm according to the method for embodiments of the invention 3 to ladle argon-blown in advance during according to the method tapping of comparative examples 3.
Embodiment 4:
With the half steel after the vanadium extraction is that raw material is smelted pipe line steel, this steel grade finished product internally controlling requirement nitrogen in steel content≤40ppm.
Half steel after the vanadium extraction directly is blended into converter and smelts after hot metal pretreatment (mainly being to take off S), the converter nominal capacity is 120t.Going into stove half steel carbon content is 3.82%, and sulphur content is 0.003%, and half steel weight is 136.82t, and temperature is 1342 ℃, and through check and analysis, going into stove half steel nitrogen content is 46ppm, and half steel begins oxygen blast after being blended into converter.The omnidistance argon pattern that supplies is adopted in converter bottom blowing this moment: the converter bottom is provided with six blocks of gas permeable bricks, and blowing single brick nitrogen flow in early stage is 50Nm
3/ h, total air supply intensity is 0.037m
3/ (mint), the single brick gas supply flow of 9min～11min is 80Nm for supplying the argon flow
3/ h, total air supply intensity is 0.060m
3/ (mint), supplying the argon flow behind the 11min is 120Nm
3/ h, total air supply intensity is 0.089m
3/ (mint).
When be 10min tap to tap time, in converter, add whipping agent 7Kg/t
Steel, smelt once success, do not re-blow.The component of said whipping agent is: the FeO of 36wt%, the Fe of 8wt%
2O
3, the CaO of 20wt%, the SiO of 8wt%
2, the MgO of 10wt%, the C of 4wt%, surplus is a unavoidable impurities.
To adding slag supplying agent adjustment slag viscosity, 1min is in advance to ladle argon-blown before the tapping before the tapping, and the intensity that ladle carries out Argon is 0.006m
3/ (mint), BOTTOM ARGON BLOWING pressure is 1.0MPa, tapping later stage pushing off the slag tapping reduces the quantity of slag under the tapping process, tapping process soft blow argon.
Get in the converter one of steel appearance before the tapping, get in the ladle one of steel appearance after the tapping, through check analysis, nitrogen content is 9.4ppm in the converter terminal molten steel, and steel appearance nitrogen content is 12.2ppm in the ladle, tapping process nitrogen pick-up 2.8ppm.
Comparative examples 4:
Except do not add whipping agent latter stage in blowing with not in advance to ladle argon-blown, the half steel of the employing method identical with method among the embodiment 4 after with vanadium extraction is the raw material smelting heavy rail steel.Nitrogen content is 14.6ppm in the converter terminal molten steel, and the molten steel nitrogen content is 19.8ppm in the ladle, tapping process nitrogen pick-up 5.2ppm.
To compare according to embodiments of the invention 4 and comparative examples 4; Can know; The converter terminal nitrogen content that obtains according to the method for comparative examples 4 wants beguine to exceed 5.2ppm according to the converter terminal nitrogen content that the method for embodiments of the invention 4 obtains, and does not want beguine in advance the method tapping process molten steel nitrogen pick-up of ladle argon-blown to be exceeded 2.4ppm according to the method for embodiments of the invention 4 to ladle argon-blown in advance during according to the method tapping of comparative examples 4.
Can know that with Comparative Examples 1 to 4 compared with prior art, can exempt from according to the method for the invention converter terminal nitrogen in steel content is controlled in the 11ppm, the tapping process nitrogen increased amount is controlled at 1ppm～3ppm by embodiment 1 to 4.Therefore, method of the present invention can reduce converter terminal nitrogen content and the nitrogen increased amount that reduces tapping process effectively.
The invention is not restricted to the foregoing description, without departing from the present invention, can carry out various distortion and modification.
Claims (7)
1. the method that half steel is smelted control nitrogen in steel content comprises converter oxygen top blown, the preceding residue adjustment processing of tapping, the pushing off the slag tapping; It is characterized in that according to the requirement of steel grade nitrogen content; In converter oxygen top blown process, adopt different bottom blowing patterns, and add whipping agent latter stage in blowing, 1min carries out BOTTOM ARGON BLOWING to ladle in advance before tapping; Tapping process carries out the operation of soft blow argon to ladle
Wherein, the component of whipping agent is: the FeO of 28wt%～45wt%, the Fe of 7wt%～10wt%
2O
3, the CaO of 18wt%～22wt%, the SiO of 6wt%～9wt%
2, the MgO of 8wt%～11wt%, the C of 3wt%～5wt%, surplus is a unavoidable impurities.
2. method according to claim 1 is characterized in that when finished product nitrogen in steel content is 40ppm～70ppm, being employed in bottom blowing nitrogen in oxygen top blown 8～10min, then the bottom blowing pattern that finishes up to tapping of blowing argon gas.
3. method according to claim 2, the air supply intensity that it is characterized in that said bottom blowing nitrogen is 0.016～0.089m
3/ (mint), the air supply intensity of argon bottom-blowing is 0.026～0.062m
3/ (mint).
4. method according to claim 1 is characterized in that adopting the oxygen top blown process bottom blowing pattern of argon bottom-blowing simultaneously when finished product nitrogen in steel content during less than 40ppm.
5. method according to claim 4, the intensity that it is characterized in that said argon bottom-blowing is 0.041～0.077m
3/ (mint).
6. method according to claim 1, the intensity that it is characterized in that in the tapping process ladle is carried out Argon is 0.003～0.007m
3/ (mint), BOTTOM ARGON BLOWING pressure is 0.6～1.3MPa.
7. method according to claim 1, the add-on that it is characterized in that whipping agent is 3Kg/t
Steel～7Kg/t
Steel
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| CN102690924B (en) * | 2012-05-25 | 2014-03-26 | 攀钢集团攀枝花钢铁研究院有限公司 | Method for controlling nitrogen content of ultra-low-carbon steel |
| CN102876834B (en) * | 2012-08-23 | 2014-04-23 | 攀钢集团研究院有限公司 | Method for modifying semisteel converter steelmaking final slag |
| CN103173586B (en) * | 2013-04-15 | 2014-12-03 | 攀钢集团攀枝花钢铁研究院有限公司 | Method for lowering contents of oxygen and nitrogen in molten steel at smelting end in semisteel smelting converter |
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| CN104745761B (en) * | 2015-04-23 | 2017-03-29 | 攀钢集团研究院有限公司 | The method of semisteel smelting converter terminal residue adjustment |
| CN104831017B (en) * | 2015-06-01 | 2016-08-24 | 山东钢铁股份有限公司 | A kind of control tapping process molten steel nitrogen pick-up device and control method |
| CN105648138B (en) * | 2016-02-25 | 2018-01-26 | 四川攀研技术有限公司 | A kind of method for reducing converter semi-steel making nitrogen content |
| CN106244765A (en) * | 2016-09-05 | 2016-12-21 | 攀钢集团攀枝花钢铁研究院有限公司 | The denitrogenation method of converter semi-steel making |
| CN107447070A (en) * | 2017-07-30 | 2017-12-08 | 湖南华菱湘潭钢铁有限公司 | A kind of Aluminum steel converter smelting method |
| CN108690898B (en) * | 2018-06-14 | 2020-01-07 | 鞍钢股份有限公司 | Accurate control method for nitrogen increase of combined blown converter |
| CN111394536A (en) * | 2020-05-06 | 2020-07-10 | 攀钢集团西昌钢钒有限公司 | Control method for N content of high-strength high-aluminum high-vanadium plate blank |
| CN113953468A (en) * | 2021-09-14 | 2022-01-21 | 包头钢铁（集团）有限责任公司 | Method for preventing molten steel from absorbing nitrogen in tapping process by pre-adding dry ice to ladle |
| CN115418441B (en) * | 2022-08-24 | 2024-02-06 | 武汉尚圆融信新型材料有限公司 | Efficient denitrification agent and denitrification method for converter tapping process |
| CN115466815B (en) * | 2022-09-27 | 2023-07-14 | 鞍钢股份有限公司 | Method for controlling nitrogen content of high-carbon steel |
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| CN1183476A (en) * | 1997-09-19 | 1998-06-03 | 沈阳东方钢铁有限公司 | Process for smelting steel |
| CN1275625A (en) * | 2000-06-07 | 2000-12-06 | 昆明理工大学 | Semi-steel dephosphorizing desulfurizing steel-making technology |
| CN102071277A (en) * | 2010-12-23 | 2011-05-25 | 攀钢集团钢铁钒钛股份有限公司 | Converter dephosphorizing and steelmaking method |
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