CN115505682B - Method for shortening smelting time of low-carbon aluminum killed steel LF furnace - Google Patents
Method for shortening smelting time of low-carbon aluminum killed steel LF furnace Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/06—Deoxidising, e.g. killing
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
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- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
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Abstract
The invention discloses a method for shortening smelting time of a low-carbon aluminum killed steel LF furnace, and belongs to the technical field of steel smelting. According to the method for shortening the smelting time of the low-carbon aluminum killed steel LF furnace, an aluminum-containing deoxidizer and an aluminum-containing alloy are added in the tapping process to deoxidize and alloy molten steel, and the addition of the deoxidizer is based on the condition that the Als content of the molten steel in an entering station of an argon blowing station is between [ the upper limit of Als content of steel grade +0.020% and the upper limit of Als content of steel grade +0.040% ]; enabling a top-blowing argon gun in the argon blowing station procedure, and carrying out 'top blowing + bottom blowing' strong stirring; after molten steel enters the LF furnace, aluminum-containing deoxidizer is added according to the Als content of the steel sample at the outlet of the argon blowing station, so that deep deoxidization of the molten steel and slag is enhanced. The smelting method can improve the LF slagging speed, remarkably improve the desulfurization effect, compress the smelting period of the LF furnace, has higher tolerance to factors which are unfavorable for the LF furnace slagging, such as the oxidizing property of molten steel at the end point of the converter, the slag quantity of the converter and the like, and is suitable for industrial mass production application.
Description
Technical Field
The invention belongs to the technical field of steel smelting, and particularly relates to a method for shortening the smelting time of a low-carbon aluminum killed steel LF furnace.
Background
The low-carbon aluminum killed steel (0.01-0.06% of C, 0.02-0.10% of Al and less than or equal to 0.03% of Si) is widely applied to the industries of automobiles, household appliances, buildings and the like. At present, four process paths are generally adopted for production in main stream steel factories at home and abroad: (1) Molten iron pretreatment, top-bottom combined blown converter, CAS-OB and continuous casting; (2) Molten iron pretreatment, top-bottom combined blowing converter, argon blowing station and continuous casting; (3) Molten iron pretreatment, top-bottom combined blowing converter, argon blowing station, RH and continuous casting; (4) Molten iron pretreatment, top-bottom combined blowing converter, argon blowing station, LF and continuous casting. The process path (4) is widely applied in the metallurgical industry due to the characteristics of strong temperature compensation capability, good desulfurization effect and the like. However, as the competition of the steel market is increased, the steel mill is urgent to reduce the production cost and improve the production efficiency, and in such a situation, the problem that the smelting time of the LF furnace exposed in the industrial mass production of the process path (4) is long seriously afflicts steel-making practitioners, and continuous process innovation is needed to overcome. According to analysis, the reason for the long smelting time of the LF furnace is mainly that the reducing slag making time of the LF furnace is long.
In the tapping process of the converter, the high-oxidability slag in the converter inevitably enters a ladle, and if properly controlled, the weight of the high-oxidability slag entering the ladle is generally about 3-5kg/t steel. The slag has strong oxidizing property, and can play a role in desulfurization after being completely deoxidized in the subsequent process. However, in actual industrial mass production, the weight of slag entering the ladle fluctuates greatly and the actual weight is difficult to detect. When the weight of slag entering the ladle is large, the smelting time of a subsequent process (LF) can be greatly prolonged, so that the production efficiency is reduced.
The LF (Ladle Furnace) furnace is external refining equipment and has the functions of adjusting the temperature of molten steel, slagging and desulfurizing, alloying, modifying and removing impurities, and the like. In the LF operation process, slag formation is very important, and the purpose of the slag formation is to modify the oxidizing slag which inevitably enters a ladle in the tapping process of a converter into reducing slag, so that conditions are created for desulfurizing molten steel and absorbing inclusions in the molten steel, and the longer the reducing slag is, the better the effects of desulfurizing and absorbing the inclusions in the molten steel are on the premise of ensuring stirring conditions. The slag forming operation is realized by adding slag forming materials to remove oxygen in molten steel and slag, and the main factors influencing the slag forming effect are the type, the adding amount and the adding time of the slag forming materials. It is generally considered that the slagging process runs through the whole process from converter tapping to LF furnace tapping, and the goal of the slagging operation is to cause the oxidizing slag to be reduced as quickly as possible.
Through retrieval, chinese patent (application publication number: CN 110564916A) discloses a method for shortening refining time of SPHC steel grade, which adopts the principle that good dynamic conditions in the tapping process of a converter are utilized, slag making materials and deoxidizers are added into molten steel in advance before and after tapping, so that rapid slag formation in the tapping process is realized, and slag making is not required to be repeated after LF entering. The application can shorten the refining time by 3-5 minutes, but does not consider the factor that the slag quantity under the converter is a variable, and in actual production, the converter frequently generates a large slag quantity, under the condition, the process operation proposed by the application is operated according to the application, and no reducing slag is formed after LF is fed, so that the effects of desulfurizing and removing steel inclusions are not enough.
Chinese patent (application publication number: CN 110735018A) discloses a method for producing low-carbon steel by rapid desulfurization of an LF furnace, which mainly comprises the following steps: the desulfurization effect is controlled and the carburetion of molten steel is reduced by controlling the parameters of bottom blowing argon and changing the lifting condition of electrodes, so that the refining period of an LF furnace can be shortened and the product quality can be improved under the condition that the components of original slag are not changed. But it has the following problems: the components of slag are not restrained, the composition of slag-making materials is not regulated, and according to the technological operation proposed by the application, only the parameters of bottom blowing argon are regulated and the lifting condition of an electrode is changed, so that the effects of desulfurizing and removing steel inclusions are not enough.
Chinese patent (issued publication number: CN 106884071A) discloses "a treatment method for refining production of low-silicon aluminum killed steel under converter low-temperature tapping condition": and before the temperature of the molten steel rises, calcium carbide is added to accelerate slag ejection modification and improve the submerged arc effect. Adding slag-forming materials (lime and fluorite) into three batches, and simultaneously blowing argon in the sequence of weak-strong-medium-weak, stopping stirring by bottom blowing argon when the top slag color is changed to green, and performing temperature measurement and sampling operation; and after the temperature measurement sampling operation is finished, regulating the flow of bottom blowing argon to a weak blowing state. According to the application, the acid-soluble aluminum burning loss in the refining treatment process can be reduced, the yield of aluminum alloy is improved, the refining treatment period is shortened, the quality of molten steel is improved, and meanwhile, the production and manufacturing cost is reduced, but only calcium carbide, lime and fluorite are added to deoxidize slag, so that the slagging effect is not guaranteed under the condition that the oxygen content of molten steel is too high, and the refining treatment period is shortened.
Chinese patent (application publication number: CN 112322837A) discloses a smelting process for high-efficiency slagging and desulfurization of LF aluminum killed steel, which is characterized in that: adding pre-deoxidized carbon powder in the tapping process, wherein the adding amount is 0.1 kg/ton of steel, lime, aluminum particles and bauxite are added according to the oxygen determination result of a converter end point sublance, the adding amount of lime is 5.0-7.5 kg/ton of steel, the adding amount of bauxite is 0.35-1.0 kg/ton of steel, and the adding amount of aluminum particles is 1.7-2.8 kg/ton of steel. However, the application does not consider the situation that the slag amount under the converter is large or the converter molten steel is seriously over-oxidized, in fact, under the situation, the adding amount of aluminum particles (1.7-2.8 kg/ton steel) is insufficient to remove oxygen in the molten steel and ladle slag, so that quick reduction slag making is difficult to realize, and the aim of high efficiency of the LF furnace is fulfilled; in addition, specific values of argon flow are mentioned for a plurality of times in S5, S6 and S8 in the application, and in practice, the ladles with different capacities want to achieve the same stirring effect, and the argon flow values are different. Therefore, this method does not have general applicability.
The technological paper LF fast white slag making process analysis (steel making 2010 3 rd stage) introduces a LF fast white slag making method under the process route of 'combined blown converter → argon station → LF→ CC', the thinking is: modifying, deslagging, deoxidizing, strong stirring, desulfurizing, alloying and removing impurities. The main measures are as follows: 1) The converter tapping slag is modified in advance, so that favorable conditions are provided for LF rapid slagging; meanwhile, the steel tapping of the converter should be strictly controlled: supplementary blowing, slag blocking, bottom blowing, ladle condition and one-time deoxidation; 2) LF treatment early stage rapid slag melting, control main points: the slag former is reasonably added in batches through rapid temperature rise, submerged arc and stirring; 3) Slag is rapidly deoxidized and strongly stirred for desulfurization. The desulfurization is carried out by strong stirring, the speed is high, and the time is short; 4) The stirring intensity and the slag viscosity are controlled, and the floating of the inclusions is ensured. The measures disclosed in the document are relatively systematic and comprehensive, and the defects are that when the converter is tapped, various factors such as supplementary blowing, slag stopping, bottom blowing, ladle condition, primary deoxidation and the like are strictly controlled, and in industrial mass production, the difficulty of controlling the factors is great, so that the application range of the proposed method is too small.
Disclosure of Invention
1. Problems to be solved
The invention aims to overcome the defects of longer smelting period and lower production efficiency of the traditional low-carbon aluminum killed steel LF furnace, and provides a method for shortening the smelting time of the low-carbon aluminum killed steel LF furnace. The smelting method can improve the LF slagging speed, remarkably improve the desulfurization effect, compress the smelting period of the LF furnace, has higher tolerance to factors which are unfavorable for the LF furnace slagging, such as the oxidizing property of molten steel at the end point of the converter, the slag quantity of the converter and the like, and is suitable for industrial mass production application.
2. Technical proposal
In order to solve the problems, the technical scheme adopted by the invention is as follows:
the invention discloses a method for shortening smelting time of a low-carbon aluminum killed steel LF furnace, which comprises the following operations:
(1) Deep deoxidizing converter tapping:
adding an aluminum-containing deoxidizer and alloy in the tapping process to deoxidize and alloy molten steel, wherein the addition of the deoxidizer is based on the condition that the Als content of the molten steel in an entering station of an argon blowing station is between [ the upper limit of the Als content of the steel grade of +0.020% and the upper limit of the Als content of the steel grade of +0.040% ];
(2) Argon blowing station procedure:
after molten steel enters an argon blowing station, firstly opening a ladle to blow argon at the bottom for middle stirring, then throwing a top-blowing argon gun for 'top blowing + bottom blowing' strong stirring, and promoting steel slag reaction; finally stopping using the top argon blowing gun, and reserving ladle bottom argon blowing for middle stirring;
(3) LF furnace refining
After molten steel enters an LF furnace, an aluminum-containing deoxidizer is added according to the Als content of a steel sample at an outlet of an argon blowing station, the addition of the aluminum-containing deoxidizer aims at reaching the target of [ the upper limit of the Als content of the steel sample of +0.020% and the upper limit of the Als content of the steel sample of +0.040% ], and the deep deoxidization of the molten steel and slag is enhanced.
According to the invention, the smelting process of the low-carbon aluminum killed steel is optimized, for example, the whole process of 'converter tapping-argon blowing station-LF furnace' keeps the molten steel deep deoxidization state, particularly the deoxidization force in the tapping process is increased, and meanwhile, the blowing process in the smelting process is optimized, particularly the bottom argon blowing and top argon blowing strong stirring are carried out on the steel ladle in the argon blowing station process, so that the smelting period of the LF furnace can be effectively shortened, and the production efficiency is improved. The technical principle of the invention is as follows:
(1) Molten steel with strong oxidizing property and converter slag enter a ladle during tapping, and deoxidizing agent is added to deeply deoxidize the molten steel and feed the ladle slagDiffusion deoxidation (2 [ Al)]+3(FeO)＝3[Fe]+(Al 2 O 3 ) The oxidability of molten steel and slag can be greatly and rapidly reduced, and good thermodynamic conditions are created for reducing slag;
(2) In the argon blowing station process, stirring is enhanced by 'top blowing and bottom blowing', so that good dynamic conditions are created for reducing slag production;
(3) In the LF procedure, means such as deep deoxidization of molten steel, diffusion deoxidization of ladle slag, reinforced stirring and the like are adopted to create good thermodynamic and kinetic conditions for reducing slag.
Further, in the argon blowing station procedure, after stirring for 2-6min in the primary bottom blowing argon, starting a top blowing argon gun, wherein the duration of 'top blowing plus bottom blowing' is 4-8min, and after the aluminum-containing deoxidizer is added, stirring for 2-6min in the ladle is continued in the bottom blowing argon.
Furthermore, aluminum-containing deoxidizer is added according to the Als content of molten steel at the end of top blowing and bottom blowing, and the addition of the aluminum-containing deoxidizer is based on the target range [ the upper limit of Als content of steel grade is required to be +0.020% and the upper limit of Als content of steel grade is required to be +0.040% ].
Further, in the argon blowing station procedure, the Als content of molten steel at the end of the top blowing and bottom blowing is equal to or more than 0.005% and is calculated according to 0.003% when the calculated result is less than or equal to 0.003%; wherein the Als content of the sample (1) is the Als content in the molten steel at the end of stirring in the initial bottom blowing argon in the argon blowing station procedure.
Further, in the tapping process of the converter, bottom argon blowing and strong stirring are carried out, slag shells are broken by bottom argon blowing and strong stirring after molten steel enters an LF furnace, then middle stirring is carried out for heating, and finally strong stirring slag formation is carried out, and by carrying out system improvement on the bottom argon blowing process in the LF process, good thermodynamic and kinetic conditions are further created for reducing slag.
Further, the temperature of the lower electrode of the LF furnace is 15-1630 ℃ in the target temperature range, and after stopping heating, the ladle bottom argon blowing is adjusted to perform strong stirring on molten steel; the strong stirring time is 3-10 minutes, the slag sample is fished out every 2-4 minutes during the strong stirring, and when the color of the slag sample is white, the strong stirring is stopped.
Further, after deoxidizing agent and alloy are added into molten steel in the tapping process, lime and bauxite are respectively added into the molten steel in the heating process of a lower electrode of an LF furnace to adjust slag quantity and ladle slag composition, wherein the lime addition quantity is 3-8 kg/ton of steel during tapping, and the bauxite addition quantity is 1.0-3.0 kg/ton of steel; the lime addition amount is 2-5 kg/ton steel and bauxite addition amount is 0.5-2.0 kg/ton steel in the heating process of the lower electrode of the LF furnace.
Further, the aluminum-containing deoxidizer refers to steelmaking auxiliary materials containing metal aluminum, and the steelmaking auxiliary materials include, but are not limited to, aluminum iron, aluminum particles and aluminum wires.
Further, the argon flow of the top-blowing argon gun is 600-1200Nl/min; the argon pressure is 0.3-1.0MPa; the gun position (the distance between the argon outlet hole of the top-blowing argon gun and the molten steel surface) is as follows: 1000-2000mm.
Furthermore, the stirring intensity is controlled by controlling the flow of argon blown from the bottom of the ladle in the smelting process, and the standard of the strong stirring is as follows: the bright surface of molten steel in the ladle is more than 300mm; the standard of the middle stirring is as follows: the bright surface of molten steel in the ladle is 50-300 mm; the criteria for weak stirring were: the bright surface of the molten steel in the ladle is less than 50mm.
In summary, compared with the prior art, the invention can obtain the following beneficial effects:
(1) According to the method for shortening the smelting time of the low-carbon aluminum killed steel LF furnace, disclosed by the invention, on one hand, the whole flow of converter tapping-argon blowing station-LF furnace is controlled to keep a molten steel deep deoxidization state, and particularly, the addition amount of a deoxidizer in the tapping process is increased; on the other hand, the argon blowing station performs 'top blowing and bottom blowing' strong stirring, and the slag making process of the traditional process is partially moved forward to the argon blowing station process from the LF furnace process, so that the smelting period of the LF furnace can be effectively shortened.
(2) The method for shortening the LF furnace smelting time of the low-carbon aluminum killed steel can not only improve the slag making speed and compress the LF furnace smelting period of the low-carbon aluminum killed steel, but also obviously improve the desulfurization effect, is particularly suitable for abnormal heats which are unfavorable for LF furnace slag making, such as large slag quantity under a converter, severe peroxidation of a converter end point and the like, and can not greatly increase the LF furnace smelting time due to large slag quantity under the converter and severe peroxidation of the converter end point.
Drawings
FIG. 1 is a process flow diagram of a method for reducing the time for smelting a low-carbon aluminum killed steel LF furnace according to the present invention.
Detailed Description
The slag discharging amount of the converter is a key parameter influencing the LF smelting period, and when the slag discharging amount is large, if the slag discharging amount is treated according to a conventional method, the LF treatment time can be obviously prolonged, and the important points are that: the detection degree of the slag quantity of the converter is low, and even if the experience of operators is rich in production practice, the slag quantity is difficult to judge, and even continuous judgment has certain difficulty. By improving the smelting process, the invention can effectively shorten the smelting time of the low-carbon aluminum killed steel LF furnace, improve the production efficiency, is especially suitable for the conditions of high oxidizing property of molten steel at the end point of the converter and large slag discharging amount of the converter, and avoids the adverse effect of serious peroxidation at the end point of the converter on the smelting time of the LF furnace due to the large slag discharging amount of the converter.
Specifically, on one hand, the invention controls the whole flow of the converter tapping-argon blowing station-LF furnace to keep the molten steel deep deoxidization state, and creates thermodynamic conditions for rapidly manufacturing the reducing slag in the LF furnace; on the other hand, through reasonable application of ladle bottom argon blowing and top argon blowing, favorable dynamic conditions are created for rapidly manufacturing reducing slag in an LF furnace, and particularly, ladle bottom argon blowing strong stirring is carried out when a converter is tapped; the argon blowing station carries out 'top blowing + bottom blowing' strong stirring; and carrying out a strong stirring slag layer breaking-medium stirring heating-strong stirring slag forming process in the LF furnace. That is, the reason why the present invention can achieve a relatively good effect is as follows: (1) the tapping and deoxidizing dosage is large; (2) a top argon blowing gun is used on the basis of ladle bottom argon blowing, the method of 'top blowing and bottom blowing' strong stirring is adopted to accelerate the melting of ladle slag, promote the reaction of steel slag, and forward the slag making function of the conventional LF to an argon blowing station process; (3) LF adds aluminum-containing deoxidizer according to the Als content of an outgoing steel sample (2) of an argon blowing station, the addition of the aluminum-containing deoxidizer aims at hit [ the upper limit of the Als content of the steel grade is required to be +0.020 percent, and the upper limit of the Als content of the steel grade is required to be +0.040 percent ], so that deep deoxidization of molten steel and slag is enhanced. It should be emphasized that, because the LF furnace smelting period is a limiting link and the argon blowing station smelting period is a non-limiting link, the prolongation of the argon blowing station smelting period in the patent does not lead to the reduction of production efficiency.
Referring to fig. 1, the method for shortening the smelting time of the low-carbon aluminum killed steel LF furnace of the invention specifically comprises the following working procedures:
(1) Adding aluminum-containing deoxidizer and alloy in the tapping process to deoxidize and alloy molten steel, and opening the ladle to blow argon for strong stirring in the tapping process. The deoxidizer is added according to the conditions that the Als content of molten steel hit by an argon blowing station is between [ the upper limit of Als content requirement of steel grade +0.020% and the upper limit of Als content requirement of steel grade +0.040% ], and the alloy is added according to the conditions that the alloy hit by the middle limit of the control range of steel grade. The aluminum-containing deoxidizer of the invention refers to steelmaking auxiliary materials containing metal aluminum, such as aluminum iron, aluminum particles, aluminum wires and the like.
(2) Adding molten steel into deoxidizer and alloy during tapping, adding slag forming materials such as lime, bauxite and the like to adjust slag quantity and ladle slag composition, wherein the lime addition quantity is 3-8 kg/ton steel, the bauxite addition quantity is 1.0-3.0 kg/ton steel, the percentage composition of lime is CaO more than or equal to 85%, and the percentage composition of bauxite is Al 2 O 3 ≥70％。
(3) Continuously stirring the molten steel in the bottom argon blowing of a ladle after the molten steel enters an argon blowing station, taking a steel sample (1) after the bottom argon blowing is carried out for 2-6min, and analyzing the content of elements such as molten steel C, si, mn, P, S, als;
(4) Taking a steel sample (1), then throwing a top-blowing argon gun on the basis of ladle bottom-blowing argon, accelerating the melting of ladle slag by adopting a means of 'top-blowing and bottom-blowing' strong stirring, and promoting the reaction of steel slag, wherein the argon flow of the top-blowing argon gun is 600-1200Nl/min, and the argon pressure is 0.3-1.0MPa; the gun position (the distance between the argon outlet hole of the top-blowing argon gun and the molten steel surface) is 1000-2000mm.
(5) After the top blowing and bottom blowing are continued for 4-8min, stopping using the top blowing argon gun, and keeping the ladle bottom blowing argon for middle stirring. Adding an aluminum-containing deoxidizer according to the analysis result of the Als content of the sample (1) and the duration time of top blowing and bottom blowing to adjust the Als content, wherein the Als content of molten steel at the end of the top blowing and bottom blowing=the sample (1) is calculated according to 0.003% when the calculation result is less than or equal to 0.003% and the Als content of the molten steel is equal to 0.005% after the end of the top blowing and bottom blowing; the addition amount of the aluminum-containing deoxidizer is based on the hit target range [ the upper limit of the Als content requirement of the steel grade +0.020% and the upper limit of the Als content requirement of the steel grade +0.040% ];
(6) Stirring the aluminum-containing deoxidizer in argon blown from the bottom of the ladle for 2-6min, taking a steel sample (2), and then hanging the ladle to an LF furnace;
(7) After molten steel enters an LF furnace, a ladle bottom is opened for argon blowing and strong stirring to break a slag shell, and then an aluminum-containing deoxidizer is added according to the Als content of an argon blowing station (2), wherein the aluminum-containing deoxidizer is added with the aim of hit [ the upper limit of the Als content of a steel grade is required to be +0.020 percent, and the upper limit of the Als content of the steel grade is required to be +0.040 percent ];
(8) Lower electrode heating
Before heating, adjusting the flow of argon blown into the ladle at the bottom of the ladle to be the temperature after stirring, and heating the target temperature range: 1590-1630 ℃; in the heating process, slag forming materials such as lime, bauxite and the like are added in batches to adjust the components of ladle slag, wherein the addition amount of lime is 2-5 kg/ton steel, and the addition amount of bauxite is 0.5-2.0 kg/ton steel. In order to prevent slag forming materials from forming lump, the slag forming materials are added in batches, and the adding amount of each batch is less than or equal to 3.0kg/t of steel;
(9) After stopping heating, adjusting ladle bottom argon blowing to perform strong stirring on molten steel; the strong stirring time is 3-10 minutes. And (3) during the strong stirring, dragging out a slag sample every 3min, stopping strong stirring when the color of the slag sample is white, and measuring the temperature and taking a steel sample after stopping strong stirring.
(10) Adjusting the temperature of molten steel: and (3) adjusting the content of alloy elements according to the analysis result of the steel sample (3).
(11) And feeding a calcium wire after the components and the temperature are qualified, weakly stirring, and continuously casting on an outlet.
The low-carbon aluminum killed steel comprises the following components in percentage by weight: carbon: 0.03-0.07%, si less than or equal to 0.05%, manganese: 0.10-3.0%, S is less than or equal to 0.005%, acid-soluble aluminum: 0.015-0.10%, and the balance of iron, phosphorus, titanium, niobium, vanadium, copper, chromium, nickel and unavoidable impurities. The invention is further described below by taking a process flow of '300T converter-argon blowing station-LF furnace-continuous casting' for smelting low-carbon aluminum killed steel as an example. The low carbon aluminum killed steel in the examples has the brand of DC01, and the composition requirements of the outgoing molten steel of the LF furnace are shown in the following table 1:
table 1 requirements for the composition of the outgoing molten steel from LF furnace for Steel grade to be smelted in examples 1-3
| Requirements for | C％ | Si％ | Mn％ | P％ | S％ | Als％ |
| Control requirements | 0.030-0.055 | ≤0.05 | 0.15-0.25 | ≤0.020 | ≤0.015 | 0.030-0.055 |
| Target value | 0.040 | ≤0.03 | 0.20 | ≤0.015 | ≤0.012 | 0.040 |
Example 1:
in the smelting method of the low-carbon aluminum killed steel of the embodiment, the molten steel amount is as follows: 305 tons, the specific steps are as follows:
(1) Tapping from converter
The steel ladle is opened in the tapping process, argon is blown into the steel ladle at the bottom for strong stirring, 607kg of aluminum particles and 581kg of low-carbon ferromanganese are added in the tapping process to deoxidize and alloy molten steel, the addition of the aluminum particles is based on the Als content of the molten steel which hits an argon blowing station and enters the steel station being 0.075 percent and 0.095 percent, and the addition of the low-carbon ferromanganese is based on the Als content which hits 0.20 percent;
(2) Adding 1715kg of lime and 310kg of bauxite into molten steel during tapping, adjusting slag quantity and ladle slag composition, wherein CaO content in lime is 88%, and Al in bauxite 2 O 3 76%;
(3) Continuously opening a ladle to blow argon at the bottom of the ladle after molten steel enters an argon blowing station, and stirring the molten steel in the middle; continuously blowing argon at the bottom for 4min, taking a steel sample (1), and analyzing the content of elements such as molten steel C, si, mn, P, S, als;
(4) And (3) after taking the steel sample (1), regulating the flow of argon blown from the bottom of the steel ladle to be strong stirring, blowing an argon top lance downwards, controlling the flow of argon of the top-blowing argon gun to be 700Nl/min, controlling the pressure of argon to be 0.5Mpa, and controlling the lance position to be 1200mm. The method adopts a means of strong stirring of top blowing and bottom blowing to accelerate the melting of ladle slag and promote the reaction of the steel slag;
(5) After the top blowing and bottom blowing are continued for 6min, the top blowing argon gun is stopped, and the ladle bottom blowing argon is reserved for stirring. Steel sample (1) has Als content of 0.058%, and molten steel has Als content of: 0.058% -6×0.005% = 0.028%, adding 186kg of aluminum particles to adjust the Als content, wherein the target range of Als content is 0.075% -0.095%;
(6) Stirring the aluminum particles in ladle bottom argon blowing for 5min after adding the aluminum particles, taking a steel sample (2), wherein the Als content of the sample (2) is 0.081%, and then hanging the ladle to an LF furnace;
(7) After molten steel enters an LF furnace, opening a ladle bottom argon blowing, adjusting the flow of the ladle bottom argon blowing until the bright surface of the molten steel is more than 300mm, performing strong stirring for 1min to break a slag shell, and then adding 13kg of aluminum particles according to the Als content of a steel sample (2), wherein the addition of the aluminum particles aims at hit [0.075%,0.095% ];
(8) Adjusting the flow of argon blown from the bottom of the ladle until the bright surface of molten steel is between [50-300]]After the temperature of molten steel was measured at 1574℃after the lapse of mm, the lower electrode was heated, and the heating was stopped after 18 minutes, at which time the molten steel temperature was expected to be 1628 ℃. Heating and passingLime and bauxite are added in two batches, wherein the first batch of lime is added in an amount of 600kg, the second batch of lime is added in an amount of 350kg, and bauxite is added in an amount of 140kg. The CaO content in lime is 86 percent, and the Al in bauxite 2 O 3 77%.
(9) After stopping heating, adjusting the flow of argon blowing from the bottom of the ladle until the bright surface of molten steel is more than 300mm, and carrying out strong stirring on the molten steel; and (5) taking a slag sample after the strong stirring is carried out for 9 minutes, observing the color of the slag to be white, and stopping the strong stirring. And (3) measuring the temperature of molten steel at 1585 ℃ and taking a steel sample.
(10) Adjusting the temperature of molten steel
Adjusting the content of alloy elements according to the analysis result of the steel sample (3); and feeding a calcium line after the components and the temperature are qualified, weakly stirring, and continuously casting on an outlet, wherein the chemical components of each steel sample, the components of ladle slag and the smelting period are respectively shown in tables 2-5.
TABLE 2 analysis results of chemical composition of steel sample in example 1
| Number of steel sample | C％ | Si％ | Mn％ | P％ | S％ | Als％ |
| Steel sample (1) | 0.032 | 0.008 | 0.18 | 0.012 | 0.024 | 0.058 |
| Steel sample (2) | 0.033 | 0.012 | 0.18 | 0.014 | 0.022 | 0.081 |
| Steel sample (3) | 0.035 | 0.027 | 0.19 | 0.015 | 0.004 | 0.021 |
| LF outbound | 0.041 | 0.028 | 0.21 | 0.015 | 0.003 | 0.039 |
TABLE 3 ladle slag composition for tapping from the converter and tapping from the LF in example 1
| Slag sample serial number | TFe％ | CaO％ | MgO％ | MnO％ | SiO 2 ％ | P 2 O 5 ％ | Al 2 O 3 ％ | S％ | Binary basicity |
| Tapping from converter | 20.77 | 47.82 | 10.58 | 2.78 | 11.74 | 2.64 | 2.53 | 0.14 | 4.07 |
| LF furnace outbound | 0.72 | 50.63 | 7.32 | 0.27 | 4.73 | 0.19 | 35.64 | 0.50 | 10.71 |
Table 4 smelting cycle of argon blowing station procedure in example 1
TABLE 5 LF procedure smelting cycle in example 1
Example 2
In the smelting method of the low-carbon aluminum killed steel of the embodiment, the molten steel amount is as follows: 302 tons, the specific steps are as follows:
(1) Tapping from converter
The steel ladle is opened in the tapping process, argon is blown into the steel ladle at the bottom for strong stirring, 626kg of aluminum particles and 559kg of low-carbon ferromanganese are added in the tapping process to deoxidize and alloy molten steel, the addition of the aluminum particles is based on the Als content of the molten steel which hits an argon blowing station and enters the steel station being 0.075 percent and 0.095 percent, and the addition of the low-carbon ferromanganese is based on the Als content which hits 0.20 percent;
(2) After aluminum particles and low-carbon ferromanganese are added into molten steel in the tapping process, 2350kg of lime and 900kg of bauxite are added to adjust slag quantity and ladle slag composition, wherein the CaO content in the lime is 84%, and the Al in the bauxite is added 2 O 3 75%;
(3) Continuously opening a ladle to blow argon at the bottom of the ladle after molten steel enters an argon blowing station, and stirring the molten steel in the middle; continuously blowing argon at the bottom for 2min, taking a steel sample (1), and analyzing the content of elements such as molten steel C, si, mn, P, S, als;
(4) And (3) after taking the steel sample (1), regulating the flow of argon blown from the bottom of the steel ladle to be strong stirring, blowing an argon top lance downwards, controlling the flow of argon of the top-blowing argon gun to be 1200Nl/min, controlling the pressure of argon to be 0.9Mpa, and controlling the lance position to be 600mm. The method adopts a means of strong stirring of top blowing and bottom blowing to accelerate the melting of ladle slag and promote the reaction of the steel slag;
(5) After the duration of 'top blowing and bottom blowing' is 4min, stopping using the top blowing argon gun, and keeping the ladle bottom blowing argon for middle stirring. Steel sample (1) with Als content of 0.065%, and molten steel Als content at the end of "top blowing+bottom blowing" is: 0.065% -4×0.005% = 0.045%, adding 128kg of aluminum particles to adjust the Als content, wherein the target range of Als content is 0.075% -0.095%;
(6) Stirring the aluminum particles in ladle bottom argon blowing for 8min after adding the aluminum particles, taking a steel sample (2), wherein the Als content of the sample (2) is 0.076%, and then hanging the ladle to an LF furnace;
(7) After molten steel enters an LF furnace, opening a ladle bottom argon blowing, adjusting the flow of the ladle bottom argon blowing until the bright surface of the molten steel is more than 300mm, performing strong stirring for 0.5min to break a slag shell, and then adding 27kg of aluminum particles according to the Als content of a steel sample (2), wherein the addition of the aluminum particles aims at hit [0.075%,0.095% ];
(8) Adjusting the flow of argon blown from the bottom of the ladle until the bright surface of molten steel is between [50-300]]After the time of the heating was measured at 1566℃after the time of the heating was 20 minutes, the heating was stopped at the lower electrode, and the temperature of the molten steel was expected to be 1626 ℃. Lime and bauxite are added in two batches in the heating process, wherein the first batch is 900kg in lime addition, the second batch is 300kg in lime addition, the first batch is 300kg in bauxite addition, and the second batch is 300kg in bauxite addition. The CaO content in lime is 85 percent, and the Al content in bauxite 2 O 3 76%.
(9) After stopping heating, adjusting the flow of argon blowing from the bottom of the ladle until the bright surface of molten steel is more than 300mm, and carrying out strong stirring on the molten steel; and (5) taking a slag sample after strong stirring for 4 minutes, observing the color of the slag to be white, and stopping strong stirring. Then measuring the temperature, namely taking a steel sample (3) at the temperature of 1606 ℃ of molten steel.
(10) Adjusting the temperature of molten steel
Adjusting the content of alloy elements according to the analysis result of the steel sample (3); and feeding a calcium line after the components and the temperature are qualified, weakly stirring, and continuously casting on an outlet, wherein the chemical components of each steel sample, the components of ladle slag and the smelting period are respectively shown in tables 6-9.
TABLE 6 analysis results of chemical composition of steel sample in example 2
| Number of steel sample | C％ | Si％ | Mn％ | P％ | S％ | Als％ |
| Steel sample (1) | 0.032 | 0.004 | 0.2 | 0.012 | 0.026 | 0.065 |
| Steel sample (2) | 0.033 | 0.012 | 0.21 | 0.013 | 0.020 | 0.076 |
| Steel sample (3) | 0.040 | 0.024 | 0.21 | 0.014 | 0.004 | 0.045 |
| LF outbound | 0.042 | 0.025 | 0.21 | 0.014 | 0.004 | 0.041 |
TABLE 7 ladle slag composition for tapping from the converter and tapping from the LF in example 2
| Slag sample serial number | TFe％ | CaO％ | MgO％ | MnO％ | SiO 2 ％ | P 2 O 5 ％ | Al 2 O 3 ％ | S％ | Binary basicity |
| Tapping from converter | 20.40 | 49.20 | 8.65 | 3.45 | 12.60 | 2.58 | 2.16 | 0.13 | 3.90 |
| LF furnace outbound | 0.48 | 51.42 | 7.52 | 0.41 | 4.21 | 0.17 | 34.85 | 0.44 | 12.21 |
Table 8 argon blowing station procedure smelting cycle in example 2
Table 9 LF procedure smelting cycle in example 2
Example 3:
in the smelting method of the low-carbon aluminum killed steel of the embodiment, the molten steel amount is as follows: 311 tons, the specific steps are as follows:
(1) Tapping from converter
And (3) opening a ladle to blow argon at the bottom for strong stirring in the tapping process, adding 668kg of aluminum particles and 510kg of low-carbon ferromanganese in the tapping process to deoxidize and alloy molten steel. The aluminum grain addition is based on the Als content of molten steel hit in argon blowing station is 0.075%,0.095%, and the low carbon ferromanganese addition is based on hit 0.20%;
(2) After aluminum particles and low-carbon ferromanganese are added into molten steel in the tapping process, 1600kg of lime and 370kg of bauxite are added to adjust slag quantity and ladle slag composition, wherein the CaO content in the lime is 87%, and the Al in the bauxite is added 2 O 3 74%;
(3) And (3) continuously opening the ladle bottom argon blowing after the molten steel enters an argon blowing station, and adjusting the flow of the ladle bottom argon blowing until the bright surface of the molten steel is between 50 and 300mm. Continuously blowing argon at the bottom for 5min, then taking a steel sample (1), analyzing the content of elements such as molten steel C, si, mn, P, S, als, and the like, wherein the content of Als of the steel sample (1) is 0.019 and is far lower than a target range, so that the condition that the end point of the converter is seriously over-oxidized or a large amount of slag is discharged during tapping of the converter is judged;
(4) And (3) after taking the steel sample (1), regulating the flow of argon blown from the bottom of the steel ladle until the bright surface of molten steel is more than 300mm, blowing an argon top lance downwards, controlling the flow of argon of the top argon blowing lance to be 1100Nl/min, controlling the pressure of argon to be 0.4Mpa, and controlling the lance position to be 1300mm. The method adopts a means of strong stirring of top blowing and bottom blowing to accelerate the melting of ladle slag and promote the reaction of the steel slag;
(5) After the duration of 'top blowing and bottom blowing' is 7min, stopping using the top blowing argon gun, and keeping the ladle bottom blowing argon for middle stirring. The steel sample (1) has Als content of 0.019 percent, molten steel Als content of 0.019-7 multiplied by 0.005 percent= -0.016 when 'top blowing and bottom blowing' are finished, and Als content calculation result is less than or equal to 0.003 percent, so that 271kg of aluminum particles are added to adjust Als content according to 0.003 percent, and the target range of Als content is 0.075-0.095 percent;
(6) And (3) stirring the aluminum particles in ladle bottom argon blowing for 3min after the aluminum particles are added, and taking a steel sample (2). Sample (2) had an Als content of 0.067%. The rear ladle is hung to an LF furnace;
(7) After molten steel enters an LF furnace, opening a ladle bottom argon blowing, adjusting the flow of the ladle bottom argon blowing until the bright surface of the molten steel is more than 300mm, performing strong stirring for 1min to break a slag shell, and then adding 60kg of aluminum particles according to the Als content of a steel sample (2), wherein the addition of the aluminum particles aims at hit [0.075%,0.095% ];
(8) Adjusting the flow of argon blown from the bottom of the ladle until the bright surface of molten steel is between [50-300]]After the time of the heating was measured at 1567℃and at the time of the heating at the lower electrode for 20 minutes, the heating was stopped, and the temperature of molten steel was expected to be 1625 ℃. Lime and bauxite are added in two batches in the heating process, wherein the first batch is 780kg in lime addition, the second batch is 420kg in lime addition and the bauxite is 270kg in bauxite addition. Lime and bauxite are added in batches in order to prevent slag forming materials from forming lumps, and the addition amount of each batch is less than or equal to 3.0kg/t of steel; the CaO content in lime is 88 percent, and the Al content in bauxite 2 O 3 75%;
(9) After stopping heating, adjusting the flow of argon blowing from the bottom of the ladle until the bright surface of molten steel is more than 300mm, and carrying out strong stirring on the molten steel; and (5) taking a slag sample after the strong stirring for 6 minutes, observing the color of the slag to be white, and stopping the strong stirring. Measuring the temperature before the strong stirring is finished, measuring the temperature of molten steel at 1577 ℃, and taking a steel sample (3);
(10) Adjusting the temperature of molten steel
Adjusting the content of alloy elements according to the analysis result of the steel sample (3); and feeding a calcium line after the components and the temperature are qualified, weakly stirring, and continuously casting on an outlet, wherein the chemical components of each steel sample, the components of ladle slag and the smelting period are respectively shown in tables 10-13.
TABLE 10 analysis results of chemical composition of steel sample in example 3
| Number of steel sample | C％ | Si％ | Mn％ | P％ | S％ | Als％ |
| Steel sample (1) | 0.027 | 0.007 | 0.17 | 0.014 | 0.028 | 0.019 |
| Steel sample (2) | 0.029 | 0.015 | 0.18 | 0.016 | 0.027 | 0.067 |
| Steel sample (3) | 0.032 | 0.028 | 0.19 | 0.019 | 0.003 | 0.027 |
| LF outbound | 0.041 | 0.029 | 0.19 | 0.019 | 0.003 | 0.043 |
Table 11 in example 3, end point of the converter and LF outbound ladle slag composition
| Slag sample serial number | TFe％ | CaO％ | MgO％ | MnO％ | SiO 2 ％ | P 2 O 5 ％ | Al 2 O 3 ％ | S％ | Binary basicity |
| Tapping from converter | 21.89 | 47.75 | 10.56 | 2.78 | 11.72 | 2.64 | 2.52 | 0.14 | 4.07 |
| LF furnace outbound | 0.58 | 51.67 | 7.15 | 0.37 | 3.75 | 0.18 | 35.77 | 0.53 | 13.77 |
Table 12 argon blowing station procedure smelting period (minutes) in example 3
Table 13 LF procedure smelting period (minutes) in example 3
Comparative example 1:
the smelting method of the low-carbon aluminum killed steel of comparative example 1, the molten steel amount: 308 tons, the specific steps are as follows:
(1) Tapping from converter
The steel ladle is opened in the tapping process, argon is blown into the steel ladle at the bottom for strong stirring, 428kg of aluminum particles are added in the tapping process to deoxidize molten steel, and 583kg of low-carbon ferromanganese is added in the tapping process to alloy the molten steel; the aluminum grain addition amount is based on the Als content of the molten steel which hits the argon blowing station and enters the station being 0.030 percent and 0.055 percent, and the low-carbon ferromanganese addition amount is based on the hit of 0.20 percent;
(2) Adding 615kg lime to adjust slag amount after aluminum particles and low-carbon ferromanganese are added into molten steel in the tapping process;
(3) Stirring molten steel in argon blowing at the bottom of a ladle after entering an argon blowing station, taking a steel sample (1) after 2min, analyzing the content of elements such as molten steel C, si, mn, P, S, als, and hanging the ladle to an LF furnace after taking the steel sample (1);
(4) After molten steel enters an LF furnace, ladle bottom argon blowing is carried out, slag crust breaking is carried out by strong stirring for 1min, 62kg of aluminum particles are added according to the Als content of a steel sample (1), and the addition of the aluminum particles aims at hit [0.030%,0.055% ];
(5) Regulating the flow of argon blown from the bottom of the ladle to medium stirring, measuring the temperature of molten steel to 1582 ℃, heating by a lower electrode, stopping heating after 19 minutes, and predicting the temperature of molten steel to 1626 ℃, wherein 420kg of lime is added in the heating process;
(6) After stopping heating, adjusting the flow of argon blowing from the bottom of the ladle to strong stirring; and (5) after the stirring for 5 minutes, taking out the slag sample, and observing the color of the slag sample to be black. Adding 212kg of aluminum particles, 400kg of lime and 120kg of bauxite, continuing to stir for 7 minutes, fishing out a slag sample after the strong stirring is finished, observing the color of the slag sample to be gray, adding 175kg of aluminum particles and 200kg of lime, continuing to stir for 5 minutes, fishing out the slag sample after the strong stirring is finished, observing the color of the slag sample to be white, and finishing slag formation. Measuring the temperature, the molten steel temperature is 1561 ℃, and taking a steel sample (2).
(7) Adjusting the temperature of molten steel
Adjusting the content of alloy elements according to the analysis result of the steel sample (2); and feeding a calcium line after the components and the temperature are qualified, weakly stirring, and continuously casting on an outlet, wherein the chemical components of each steel sample, the components of ladle slag and the smelting period are respectively shown in tables 14-17.
Table 14 analysis results of chemical Components of the Steel sample in comparative example 1
| Number of steel sample | C％ | Si％ | Mn％ | P％ | S％ | Als％ |
| Steel sample (1) | 0.034 | 0.008 | 0.18 | 0.01 | 0.027 | 0.026 |
| Steel sample (2) | 0.039 | 0.035 | 0.20 | 0.012 | 0.005 | 0.044 |
| LF outbound | 0.040 | 0.036 | 0.20 | 0.013 | 0.004 | 0.045 |
Table 15 Components of ladle slag for tapping and LF tapping in comparative example 1
| Slag sample serial number | TFe％ | CaO％ | MgO％ | MnO％ | SiO 2 ％ | P 2 O 5 ％ | Al 2 O 3 ％ | S％ | Binary basicity |
| Tapping from converter | 21.26 | 49.87 | 8.86 | 2.50 | 12.84 | 2.46 | 2.05 | 0.16 | 3.88 |
| LF furnace outbound | 0.74 | 50.99 | 6.62 | 0.28 | 2.74 | 0.18 | 37.96 | 0.50 | 18.60 |
Table 16 comparative example 1 argon blowing station process smelting cycle (minutes)
| Middle stirring after entering station | Taking the steel sample (1) time consuming | Argon blowing station process smelting cycle |
| 2 | 0.5 | 2.5 |
Table 17 comparative example 1 LF procedure smelting period (minutes)
The following table is attached:
comparative example 2:
the smelting method of the low-carbon aluminum killed steel of comparative example 2, the molten steel amount: 315 tons, the specific steps are as follows:
(1) Tapping by a converter. And (5) opening a ladle in the tapping process, and performing bottom argon blowing and strong stirring. Adding 487kg of aluminum particles in the tapping process to deoxidize molten steel, and adding 517kg of low-carbon ferromanganese to alloy the molten steel; the aluminum grain addition amount is based on the Als content of the molten steel which hits the argon blowing station and enters the station being 0.030 percent and 0.055 percent, and the low-carbon ferromanganese addition amount is based on the hit of 0.20 percent;
(2) Adding 660kg of lime to adjust slag quantity after aluminum particles and low-carbon ferromanganese are added into molten steel in the tapping process;
(3) Stirring the molten steel in argon blowing at the bottom of a ladle after the molten steel enters an argon blowing station, taking a steel sample (1) after 2min, and analyzing the content of elements such as molten steel C, si, mn, P, S, als. And (3) taking a steel sample (1), and then hanging the ladle to an LF furnace. The steel sample (1) has Als content of 0.007 percent which is far lower than the target range, thus judging that the end point of the converter is seriously over-oxidized or a large amount of slag is discharged when the converter is tapped;
(4) After molten steel enters an LF furnace, ladle bottom argon blowing is carried out, slag crust breaking is carried out by strong stirring for 1min, 117kg of aluminum particles are added according to the Als content of a steel sample (1), and the addition of the aluminum particles aims at hit [0.030%,0.055% ];
(5) And regulating the flow of argon blown from the bottom of the ladle to medium stirring, measuring the temperature of molten steel to 1586 ℃, heating by a lower electrode, and stopping heating after heating for 18 minutes, wherein the temperature of molten steel is expected to be 1624 ℃. Adding 500kg of lime into the furnace in the heating process;
(6) After stopping heating, adjusting the flow of argon blowing from the bottom of the ladle to strong stirring; and (5) after the stirring for 5 minutes, taking out the slag sample, and observing the color of the slag sample to be black. And (3) continuing to stir strongly for 7 minutes after 200kg of aluminum particles, 300kg of lime and 150kg of bauxite are added, fishing out a slag sample after the strong stirring is finished, observing that the color of the slag sample is black, continuing to stir strongly for 5 minutes after 200kg of aluminum particles and 200kg of lime are added, fishing out the slag sample after the strong stirring is finished, observing that the color of the slag sample is gray, continuing to stir strongly for 5 minutes after 180kg of aluminum particles and 150kg of lime are added, fishing out the slag sample after the strong stirring is finished, observing that the color of the slag sample is white, and finishing slag making. Measuring the temperature, namely taking a steel sample (2) at the temperature of 1552 ℃ of molten steel.
(7) Adjusting the temperature of molten steel
Adjusting the content of alloy elements according to the analysis result of the steel sample (2); and feeding a calcium line after the components and the temperature are qualified, weakly stirring, and continuously casting on an outlet, wherein the chemical components of each steel sample, the components of ladle slag and the smelting period are respectively shown in tables 18-21.
Table 18 analysis results of chemical composition of steel sample in comparative example 2
| Number of steel sample | C％ | Si％ | Mn％ | P％ | S％ | Als％ |
| Steel sample (1) | 0.027 | 0.007 | 0.17 | 0.011 | 0.024 | 0.007 |
| Steel sample (2) | 0.042 | 0.041 | 0.21 | 0.018 | 0.006 | 0.024 |
| LF outbound | 0.042 | 0.040 | 0.21 | 0.019 | 0.005 | 0.042 |
Table 19 Components of ladle slag for tapping and LF tapping in comparative example 2
| Slag sample serial number | TFe％ | CaO％ | MgO％ | MnO％ | SiO 2 ％ | P 2 O 5 ％ | Al 2 O 3 ％ | S％ | Binary basicity |
| Tapping from converter | 21.03 | 51.20 | 8.87 | 2.29 | 12.31 | 2.28 | 1.87 | 0.15 | 4.16 |
| LF furnace outbound | 0.86 | 49.83 | 6.30 | 0.25 | 2.86 | 1.21 | 38.28 | 0.40 | 17.42 |
Table 20 comparative example 2 argon blowing station procedure smelting period (minutes)
| Middle stirring after entering station | Taking the steel sample (1) time consuming | Argon blowing station process smelting cycle |
| 2 | 0.5 | 2.5 |
Table 21 smelting period (minutes) of LF procedure in comparative example 2
The following table is attached:
as can be seen from the comparison of examples 1 and 3 with comparative examples 1 and 2, the low carbon aluminum killed steel smelting process of the present invention was applied:
1) The converter endpoint has no serious peroxidation or slag discharging heat, the LF furnace smelting period is 50.8 minutes, and is shortened by 12.7 minutes compared with the current process LF furnace smelting period (63.5 minutes);
2) The smelting period of the LF furnace is 49.5 minutes, which is reduced by 20 minutes compared with the smelting period (69.5 minutes) of the LF furnace in the prior art.
3) The converter endpoint has no serious peroxidation or slag discharging heat, the comprehensive desulfurization rate of argon blowing station and LF is 86.1%, and is improved by 1.1% compared with the comprehensive desulfurization rate (85%) of the prior art;
4) The comprehensive desulfurization rate of the argon blowing station and LF is 89% compared with the comprehensive desulfurization rate (79%) of the prior art, and the comprehensive desulfurization rate of the converter is improved by 10%.
Claims (9)
1. The method for shortening the smelting time of the low-carbon aluminum killed steel LF furnace is characterized by comprising the following operations:
(1) Deep deoxidizing converter tapping:
adding an aluminum-containing deoxidizer and alloy in the tapping process to deoxidize and alloy molten steel, wherein the addition of the deoxidizer is based on the condition that the Als content of the molten steel in an entering station of an argon blowing station is between [ the upper limit of the Als content of the steel grade of +0.020% and the upper limit of the Als content of the steel grade of +0.040% ];
(2) Argon blowing station procedure:
after molten steel enters an argon blowing station, firstly opening a ladle to blow argon at the bottom for carrying out medium stirring for 2-6min and taking a steel sample (1), then throwing a top-blowing argon gun for carrying out 'top blowing and bottom blowing' strong stirring to promote steel slag reaction, wherein the duration of 'top blowing and bottom blowing' is 4-8min, and adding an aluminum-containing deoxidizer according to the Als content of the molten steel at the end of 'top blowing and bottom blowing', wherein the addition amount of the aluminum-containing deoxidizer is based on the hit target range [ the upper limit of Als content of steel grade +0.020% and the upper limit of Als content of steel grade +0.040% ]; finally stopping using the top argon blowing gun, and keeping the ladle bottom argon blowing process for stirring for 2-6min;
(3) LF furnace refining
After molten steel enters an LF furnace, an aluminum-containing deoxidizer is added according to the Als content of the steel sample at the outlet of the argon blowing station, and the addition of the aluminum-containing deoxidizer aims at reaching the target of [ the upper limit of the Als content of the steel sample of +0.020% and the upper limit of the Als content of the steel sample of +0.040% ].
2. The method for shortening the smelting time of the low-carbon aluminum killed steel LF furnace according to claim 1, which is characterized by comprising the following steps: molten steel Als content=sample (1) Als content- "Top-blowing+bottom-blowing" duration (min) ×0.005% at the end of "Top-blowing+bottom-blowing" in argon blowing station procedure, when the calculation result is less than or equal to 0.003%, calculating according to 0.003%; wherein the Als content of the sample (1) is the Als content in the molten steel at the end of stirring in the initial bottom blowing argon in the argon blowing station procedure.
3. The method for shortening the smelting time of the low-carbon aluminum killed steel LF furnace according to claim 1 or 2, wherein the method comprises the following steps of: and (3) performing bottom argon blowing strong stirring during converter tapping, performing bottom argon blowing strong stirring to break a slag shell after molten steel enters an LF furnace, performing medium stirring heating, and performing strong stirring slag making.
4. A method for shortening the smelting time of a low-carbon aluminum killed steel LF furnace according to claim 3, wherein: the temperature rise target temperature range in the LF furnace lower electrode heating process is 1590-1630 ℃, and after stopping heating, the ladle bottom argon blowing is adjusted to carry out strong stirring on molten steel; the strong stirring time is 3-10 minutes, the slag sample is fished out every 2-4 minutes during the strong stirring, and when the color of the slag sample is white, the strong stirring is stopped.
5. The method for shortening the smelting time of the low-carbon aluminum killed steel LF furnace according to claim 1 or 2, wherein the method comprises the following steps of: after deoxidizing agent and alloy are added into molten steel in the tapping process, lime and bauxite are respectively added into the molten steel in the heating process of a lower electrode of an LF furnace to adjust slag quantity and ladle slag composition, wherein the lime addition quantity is 3-8 kg/ton of steel during tapping, and the bauxite addition quantity is 1.0-3.0 kg/ton of steel; the lime addition amount is 2-5 kg/ton steel and bauxite addition amount is 0.5-2.0 kg/ton steel in the heating process of the lower electrode of the LF furnace.
6. The method for shortening the smelting time of the low-carbon aluminum killed steel LF furnace according to claim 1 or 2, wherein the method comprises the following steps of: the aluminum-containing deoxidizer refers to steelmaking auxiliary materials containing metal aluminum.
7. The method for shortening the smelting time of the low-carbon aluminum killed steel LF furnace according to claim 6, which is characterized in that: the aluminum-containing deoxidizer is aluminum iron, aluminum particles or aluminum wires.
8. The method for shortening the smelting time of the low-carbon aluminum killed steel LF furnace according to claim 1 or 2, wherein the method comprises the following steps of: argon flow of the top-blowing argon gun is 600-1200Nl/min; the argon pressure is 0.3-1.0MPa; the gun position is: 1000-2000mm.
9. The method for shortening the smelting time of the low-carbon aluminum killed steel LF furnace according to claim 1 or 2, wherein the method comprises the following steps of: in the smelting process, the stirring intensity is controlled by controlling the flow of argon blown from the bottom of the ladle, and the standard of strong stirring is as follows: the bright surface of molten steel in the ladle is more than 300mm; the standard of the middle stirring is as follows: the bright surface of molten steel in the ladle is 50-300 mm; the criteria for weak stirring were: the bright surface of the molten steel in the ladle is less than 50mm.
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| CN102051435A (en) * | 2009-11-10 | 2011-05-11 | 攀钢集团钢铁钒钛股份有限公司 | Method for smelting low-carbon aluminium-killed steel and method for continuously casting low-carbon aluminium-killed steel |
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