CN115386680B - Method for precisely controlling content of molten steel [ Al ] at end point of LF furnace - Google Patents
Method for precisely controlling content of molten steel [ Al ] at end point of LF furnace Download PDFInfo
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- CN115386680B CN115386680B CN202210972619.3A CN202210972619A CN115386680B CN 115386680 B CN115386680 B CN 115386680B CN 202210972619 A CN202210972619 A CN 202210972619A CN 115386680 B CN115386680 B CN 115386680B
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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
- C21C7/0075—Treating in a ladle furnace, e.g. up-/reheating of molten steel within the ladle
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/71—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited
- G01N21/718—Laser microanalysis, i.e. with formation of sample plasma
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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
- C21C2300/00—Process aspects
- C21C2300/06—Modeling of the process, e.g. for control purposes; CII
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Abstract
The invention discloses a method for precisely controlling the content of molten steel [ Al ] at the end point of an LF furnace, belonging to the field of molten steel refining. It includes S1: stopping the production operation of the LF furnace within 15-20min from the outbound time in the refining process of the LF furnace; s2: taking a ladle top slag sample, and after the slag sample is yellowish white or bluish white, inserting LIBS probes at regular intervals for online analysis of the content of molten steel [ Al ], and continuously analyzing and calculating the linear attenuation rate of [ Al ] in steel along with time; s3: and establishing an aluminum wire feeding quantity model to guide wire feeding operation. Aiming at the problem that the content of [ Al ] is difficult to control accurately in the existing molten steel refining process, the invention utilizes the LIBS technology, is based on the application of an LIBS molten steel component online detection system in the LF refining process, directly analyzes the change rule of the content of [ Al ] in steel through no time delay, accurately controls the content of [ Al ] in the steel in the LF refining process and the end point, and reduces the fluctuation of the content of [ Al ] in the molten steel of upper and lower heat.
Description
Technical Field
The invention belongs to the technical field of molten steel refining, and particularly relates to a method for accurately controlling the content of molten steel [ Al ] at an end point of an LF furnace.
Background
The conventional detection method of molten steel components in the refining process comprises a series of procedures of sampling, cooling, sample preparation, spectrum analysis and the like, 4-6min is needed from sampling to component reporting, the molten steel components in the ladle change due to the reaction of molten steel and liquid refining slag and the oxidation of molten steel contacted with air in the waiting process, proper compensation is usually needed by experience when the molten steel components are regulated, in order to ensure the refining efficiency and the production rhythm, the sampling times are strictly limited, the production process cannot be guided in real time, and the accurate control of the molten steel components cannot be realized.
After aluminum-based alloy is added into ladle molten steel in the refining process of an LF furnace, as aluminum oxidability is active, dissolved aluminum in the steel continuously reacts with ladle top slag and oxygen in air to generate aluminum oxide, the aluminum oxide enters slag, the [ Al ] content in the molten steel is attenuated along with the aluminum oxide, and the [ Al ] attenuation rate of the molten steel is greatly different along with the [ Al ] content in the steel and the reducibility of the ladle top slag, so that quantitative determination cannot be realized. Therefore, the fluctuation of [ Al ] content in molten steel is larger at the refining end point of the LF furnaces of the upper and lower furnace times of the same continuous casting group, the fluctuation value of 0.01% of high [ Al ] steel (0.045-0.06%) can be achieved, and the fluctuation value of 0.006% of low [ Al ] steel (0.015-0.04%) can be achieved.
Through retrieval, a great deal of literature has been disclosed for controlling the content of [ Al ] in molten steel in the smelting process, such as a method (CN 111455137A) for accurately controlling the aluminum consumption of IF steel, 20g steel aluminum wire feeding control [ Als ] process practice, 150tRH refining end point molten steel acid-soluble aluminum content control, ripple steel CSP molten steel acid-soluble aluminum control, small square billet aluminum steel production practice and the like. As can be seen from the study on the above related technical solutions, the problems in the prior art are mainly:
1) The aluminum control mode is mainly based on an empirical model or formula based on historical data, so that the aluminum control accuracy is low, and the control accuracy of +/-15 ppm cannot be achieved;
2) The empirical model or formula cannot be effectively applied to all the heat, and the process control parameters of a small amount of heat exceed the boundary conditions of the empirical model in actual production, so that the control error of the Al content of molten steel is large, and the stability of the quality of molten steel is seriously affected.
Disclosure of Invention
1. Problems to be solved
Aiming at the problem that the content of [ Al ] is difficult to control accurately in the existing molten steel refining process, the invention provides a method for controlling the content of [ Al ] in the molten steel at the end point of an LF furnace accurately.
2. Technical proposal
Laser induced breakdown spectroscopy (1 aser induced breakdown spec-troscopy, LIBS) is an emerging detection technique that uses the emission spectrum of pulsed laser excitation to analyze the composition and concentration of a substance. In recent years, the method is widely applied to the fields of material analysis, industrial production control, biomedicine and the like. The LIBS analysis does not need sample preparation, has strong real-time performance, can perform quick and remote non-contact measurement, has trace element quantitative analysis capability, is suitable for online component detection in high-temperature occasions such as steel smelting, does not need sample preparation, has strong real-time performance, and can rapidly and continuously obtain molten steel components in the steelmaking process.
According to the invention, based on the LIBS online component measurement technology, a LIBS system is adopted in the middle and later stages of LF refining, the content of molten steel [ Al ] is measured online without delay in each interval period, the attenuation rate of [ Al ] along with time is calculated, the attenuation rate is multiplied by the interval (min) from the last measurement time to the outbound time, and the attenuation amount of molten steel [ Al ] in the time period is obtained, so that a ton steel feeding aluminum wire formula model is established to guide wire feeding operation, and the accurate control of the end point [ Al ] content of the LF is realized.
Specifically, S1: stopping the production operation of the LF furnace within 15-20min from the outbound time in the refining process of the LF furnace;
the invention is operated according to the conventional process after the LF furnace enters the station, and comprises heating, adjusting alloy components, producing ladle white slag and the like, and according to the LF end point [ Al ] content required by steel types: if the steel is high [ Al ], coarsely adjusting the [ Al ] in the steel to 0.03-0.040%; the low Al steel is prepared through coarse regulation of Al content to 0.008-0.012%. The temperature of the molten steel is heated to the absolute value of the temperature decay in the last heating temperature=target temperature+the later weak casting (slight fluctuation of the slag surface of the ladle and no exposed surface of the molten steel) process of the steel grade. And (2) during 15-20min from the outbound time, the LF furnace does not heat, adjust alloy components and make ladle white slag, and the process enters S2.
S2: taking a ladle top slag sample, after the slag sample is yellowish white or bluish white, inserting a LIBS probe at each uniform interval for online analysis of the content of molten steel [ Al ], continuously analyzing for multiple times, and calculating the linear attenuation rate of [ Al ] in steel along with time: delta Al/min;
specifically, a LIBS probe is inserted at 1-2min intervals uniformly to analyze the [ Al ] content of molten steel on line for 5-10 times continuously, and the linear attenuation rate of [ Al ] in steel over time is automatically calculated by z: delta Al/min; in the analysis process, the bottom argon blowing amount of the steel ladle is regulated to slightly fluctuation of the slag surface of the steel ladle, and no molten steel is exposed on the surface.
S3: and establishing an aluminum wire feeding quantity model, and guiding wire feeding operation according to the calculated quantity of the model.
In particular, according to steel grade LF furnace end point [ Al]Content requirement [ Al] target (%); steel grade [ Al ] measured by LIBS for the last time]The content is as follows: [ Al] final (%); time t between molten steel outlet time point of LF furnace and last time of measuring time point by LIBS final (min), calculating the feeding amount of the aluminum wires to be added with metal aluminum alloying: aluminum wire add (kg/ton steel)
Aluminum wire add ＝([Al] target -[Al] final +|△[Al]/min|×t final )×10。
Randomly adopting a wire feeding machine to calculate the aluminum wire add Adding molten steel in a wire feeding mode by the total feeding amount of the aluminum wire obtained by multiplying the weight (ton) of the molten steel; and after the wire feeding process and the wire feeding end, the argon blowing amount at the bottom of the ladle is not adjusted, so that the slag surface of the ladle is kept slightly fluctuated, and the exposed surface of molten steel is avoided.
S4: before the molten steel is discharged, a LIBS probe is inserted to analyze the content of molten steel [ Al ] on line, and the molten steel is discharged to the next working procedure.
3. Advantageous effects
Compared with the prior art, the invention can effectively and accurately control the content of molten steel [ Al ] at the end point of the LF furnace based on the LIBS on-line component measurement technology, the accuracy of the method can be stabilized within +/-10 ppm, and the stability of the aluminum content of the molten steel between the upper furnace pass and the lower furnace pass is effectively controlled.
Detailed Description
The invention is further described below in connection with specific embodiments.
Example 1
The invention is further illustrated by taking a 120 ton LF refining furnace in a factory to produce aluminum-containing steel grades as an example. The 4 furnace tests were carried out during the production of 10B21 (low aluminium steel) and ML08AL (high aluminium steel), respectively, as follows.
S1, stopping production operation of the LF furnace within 15-20min from the outbound time in the refining process of the LF furnace;
after the LF furnace enters a station, the operation is carried out according to the conventional process, including heating, adjusting alloy components, making white slag from ladle top slag and the like, and the content of [ Al ] at the LF end point is determined according to the steel grade requirement: 1) When 10B21 (low-aluminum steel) is produced, the [ Al ] in the steel is coarsely regulated to 0.008-0.012%; 2) When ML08AL (high-alumina steel) is produced, the [ Al ] in the steel is roughly regulated to 0.03-0.040%. The temperature of the molten steel is heated to the final heating temperature required by the steel grade=target temperature+absolute value of temperature attenuation in the process of late weak casting (slight fluctuation of the slag surface of the ladle and no exposed surface of the molten steel) of the LF furnace; after 15-20min from the outlet time to the outlet, the LF furnace does not heat, adjust alloy components and make white slag from ladle top slag,
s2: taking a ladle top slag sample, after the slag sample is yellowish white or bluish white, inserting LIBS probes at intervals of 1-2min to analyze the content of molten steel [ Al ] on line, continuously analyzing for 5-10 times, and adjusting the bottom argon blowing amount of the ladle to slightly fluctuation of the slag surface of the ladle without exposing the surface of the molten steel;
according to the online analysis value of the continuous molten steel [ Al ], automatically calculating the linear attenuation rate of [ Al ] in the steel along with time, wherein the specific situation of the aluminum attenuation rate (delta [ Al ]/min) of each furnace is shown in a table 1;
s3: according to the end point [ Al ] of steel LF furnace]Content requirement [ Al] target (%); steel grade [ Al ] measured by LIBS for the last time]The content is as follows: [ Al] final (%); time t between molten steel outlet time point of LF furnace and last time of measuring time point by LIBS final (min), calculate the requiredFeeding amount of aluminum wires alloyed by metal aluminum: aluminum wire add (kg/ton steel)
Aluminum wire add ＝([Al] target -[Al] final +|(△[Al]/min)|×t final )×10；
The calculated aluminum wire is then fed by a wire feeder add Adding molten steel in a wire feeding mode by the total feeding amount of the aluminum wire obtained by multiplying the weight (ton) of the molten steel; after the wire feeding process and the wire feeding end, the argon blowing amount at the bottom of the ladle is not adjusted, so that slight fluctuation of the slag surface of the ladle is kept, and the exposed surface of molten steel is avoided;
s4: before the molten steel is discharged, a LIBS probe is inserted to analyze the content of molten steel [ Al ] on line, and the molten steel is discharged to the next working procedure.
The aluminum content control of the molten steel for each furnace is shown in Table 2.
TABLE 1 on-line measurement of aluminum decay Rate in molten Steel Using LIBS System
TABLE 2 molten steel process control aluminum specific case
The results of the embodiment show that after the technical scheme is adopted, the control accuracy of the key aluminum content of the LF of the high-aluminum and low-aluminum steel seeds is stabilized within +/-10 ppm, and the stability of the aluminum content of molten steel between the upper furnace pass and the lower furnace pass is effectively controlled.
The examples of the present invention are merely for describing the preferred embodiments of the present invention, and are not intended to limit the spirit and scope of the present invention, and those skilled in the art should make various changes and modifications to the technical solution of the present invention without departing from the spirit of the present invention.
Claims (4)
1. A method for precisely controlling the content of molten steel [ Al ] at the end point of an LF furnace is characterized by comprising the following steps: comprising the following steps:
s1: stopping the production operation of the LF furnace within 15-20min from the outbound time in the refining process of the LF furnace;
s2: taking a ladle top slag sample, after the slag sample is yellowish white or bluish white, inserting LIBS probes at 1-2min intervals to analyze the content of molten steel [ Al ] on line, continuously analyzing for 5-10 times, and calculating the linear attenuation rate of [ Al ] in the steel along with time: delta Al/min; in the online analysis process, the bottom argon blowing amount of the ladle is regulated to slightly fluctuation of the slag surface of the ladle, and no molten steel is exposed on the surface;
s3: establishing an aluminum wire feeding quantity model, and guiding wire feeding operation according to the calculated quantity of the model;
the aluminum wire feeding quantity model is as follows:
aluminum wire add =（[Al] target -[Al] final +|(△[Al]/min)|×t final ）×10；
Aluminum wire add The feeding quantity of aluminum wires which are alloyed by metal aluminum is required to be added, and the feeding quantity is kg/ton of steel; [ Al] target End point of steel LF furnace [ Al]Content requirement,%; [ Al] final Steel grade [ Al ] measured by LIBS for the last time]Content,%; t is t final And the time length between the molten steel outlet time point of the LF furnace and the last time of measuring the time point by using LIBS is min.
2. The method for precisely controlling the [ Al ] content of the final molten steel of the LF furnace according to claim 1, which is characterized in that: and S1, stopping the production operation of the LF furnace, and specifically, stopping the operation of heating, alloy component adjustment and ladle white slag adjustment of the LF furnace.
3. The method for precisely controlling the [ Al ] content of the final molten steel of the LF furnace according to claim 1, which is characterized in that: and S3, after the wire feeding process and the wire feeding end, the argon blowing amount at the bottom of the ladle is not adjusted, the slight fluctuation of the slag surface of the ladle is still kept, and the exposed surface of molten steel is avoided.
4. A method for precisely controlling the [ Al ] content of an end point molten steel of an LF furnace according to any one of claims 1 to 3, characterized in that: further comprising S4: before the molten steel is discharged, a LIBS probe is inserted to analyze the content of molten steel [ Al ] on line, and the molten steel is discharged to the next working procedure.
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| CN103614513A (en) * | 2013-12-04 | 2014-03-05 | 南京钢铁股份有限公司 | Calcium treatment method under special steelmaking process |
| WO2020113951A1 (en) * | 2018-12-05 | 2020-06-11 | 南京钢铁股份有限公司 | Tmcp low-temperature steel plate for voc storage tanks of ships and manufacturing method therefor |
| CN111455137A (en) * | 2020-05-06 | 2020-07-28 | 攀钢集团西昌钢钒有限公司 | Method for accurately controlling aluminum consumption of IF steel |
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| CN113832300A (en) * | 2021-08-27 | 2021-12-24 | 马鞍山钢铁股份有限公司 | Prediction-based IF steel refining finishing total oxygen control method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110760748B (en) * | 2018-07-27 | 2021-05-14 | 宝山钢铁股份有限公司 | Spring steel with excellent fatigue life and manufacturing method thereof |
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Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103614513A (en) * | 2013-12-04 | 2014-03-05 | 南京钢铁股份有限公司 | Calcium treatment method under special steelmaking process |
| WO2020113951A1 (en) * | 2018-12-05 | 2020-06-11 | 南京钢铁股份有限公司 | Tmcp low-temperature steel plate for voc storage tanks of ships and manufacturing method therefor |
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