CN108690898B - Accurate control method for nitrogen increase of combined blown converter - Google Patents
Accurate control method for nitrogen increase of combined blown converter Download PDFInfo
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- CN108690898B CN108690898B CN201810611306.9A CN201810611306A CN108690898B CN 108690898 B CN108690898 B CN 108690898B CN 201810611306 A CN201810611306 A CN 201810611306A CN 108690898 B CN108690898 B CN 108690898B
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 102
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 51
- 238000000034 method Methods 0.000 title claims abstract description 32
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 41
- 239000001301 oxygen Substances 0.000 claims abstract description 41
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 41
- 238000010079 rubber tapping Methods 0.000 claims abstract description 37
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 36
- 239000010959 steel Substances 0.000 claims abstract description 36
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 34
- 238000007664 blowing Methods 0.000 claims abstract description 31
- 238000003723 Smelting Methods 0.000 claims abstract description 22
- 239000007789 gas Substances 0.000 claims abstract description 18
- 229910052742 iron Inorganic materials 0.000 claims abstract description 17
- 230000004907 flux Effects 0.000 claims abstract description 14
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 11
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 7
- 239000000779 smoke Substances 0.000 claims abstract description 7
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 6
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 6
- 229910000514 dolomite Inorganic materials 0.000 claims description 6
- 239000010459 dolomite Substances 0.000 claims description 6
- 239000004571 lime Substances 0.000 claims description 6
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 abstract description 34
- 229910052786 argon Inorganic materials 0.000 abstract description 17
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 239000010703 silicon Substances 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 229910052717 sulfur Inorganic materials 0.000 description 3
- 229910000976 Electrical steel Inorganic materials 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 239000010955 niobium Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/30—Regulating or controlling the blowing
- C21C5/35—Blowing from above and through the bath
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
Abstract
The invention provides an accurate control method for nitrogen increase of a combined blown converter, wherein molten iron meets the following conditions: c: 4.2-4.5% Si: 0.3-0.6% Mn: 0.15-0.25% P: 0.060 to 0.085%. S0.001 &0.005%, molten iron temperature: 1290-1330 ℃; the oxygen supply intensity of the converter is controlled to be 3.0-3.5 Nm3Min. t; the total addition amount of the flux in the smelting process of the converter is controlled to be 45-55 kg/t, the converter is provided with a sublance, and the oxygen supply intensity is controlled to be 1.8-2.1 Nm during TSC (thyristor controlled reactor) test of the sublance3Min. t; after the blowing begins, the movable smoke hood descends to a position 100-200 mm away from the furnace mouth; after the converter gas is recovered, controlling the micro-positive pressure of a converter mouth within the range of 0-20 Pa; controlling the air supply flow of the bottom gun, the switching time and the target nitrogen content; FeSi75 is adopted for deoxidation in the tapping process, and the adding amount is controlled according to the terminal oxygen value of the converter. The nitrogen content of the molten steel in the converter argon station can be stabilized within a certain range of 40 ppm-100 ppm.
Description
Technical Field
The invention relates to the technical field of a control method for increasing nitrogen of a converter, in particular to an accurate control method for increasing nitrogen of a combined blown converter.
Background
Due to the different functions of nitrogen in steel grades, when vanadium, titanium, aluminum, niobium, etc. are contained in steel, the formed nitrides can improve the strength of the steel. Therefore, military steel and high-silicon steel have certain requirements on the nitrogen content in steel, and the nitride in the high-silicon steel can also play the role of an inhibitor. The accurate control of the nitrogen content of steel grades is more and more important for the steel grades, and the stable control of the nitrogen content in steel in the converter process plays a key role in the stable control of the nitrogen content of steel billets.
Disclosure of Invention
In order to solve the problems in the background art, the invention provides a method for accurately controlling nitrogen increase of a combined blown converter, which controls the flow and pressure of a bottom gun by the requirements of the combined blown converter on molten iron conditions during smelting, the control of unit consumption of a flux in the smelting process, the requirements of the combined blown converter and the control of the switching time of nitrogen and argon of the bottom gun, and can stabilize the nitrogen content of molten steel in an argon station of the converter in a certain range of 40 ppm-100 ppm by the silicon deoxidation operation of the molten steel in the tapping process.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for accurately controlling nitrogen increase of a combined blown converter comprises the following steps:
(1) the molten iron satisfies the following conditions: c: 4.2-4.5% Si: 0.3-0.6% Mn: 0.15-0.25% P: 0.060 to 0.085%. 0.001-0.005% of S, molten iron temperature: 1290-1330 ℃;
(2) the oxygen supply intensity of the converter is controlled to be 3.0-3.5 Nm3/min·t；
(3) The total addition amount of a flux in the converter smelting process is controlled to be 45-55 kg/t, and the flux comprises active lime and light-burned dolomite;
(4) the converter is provided with a sublance, and the oxygen supply intensity is controlled to be 1.8-2.1 Nm during TSC test of the sublance3/min·t；
(5) After the blowing begins, the movable smoke hood descends to a position 100-200 mm away from the furnace mouth;
(6) after the converter gas is recovered, controlling the micro-positive pressure of a converter mouth within the range of 0-20 Pa;
7) the number of converter bottom guns is 5-10, and the air supply flow, the switching time and the target nitrogen content of the bottom guns are as follows:
when the target nitrogen content is controlled to be 40-60 ppm and 40-60 ppm, the oxygen blowing time period is divided into 10 oxygen steps, and N is in the penultimate oxygen step2Switching to Ar till tapping is finished;
controlling the target nitrogen content between 61ppm and 80ppm, and N in the blowing TSC test2Switching to Ar till tapping is finished;
when the target nitrogen content is controlled to 81-100 ppm, N is added at the beginning of tapping2Switching to Ar till tapping is finished;
the target nitrogen content indicates the mass percentage of nitrogen elements in molten steel in a steel ladle after the steel is finished;
the air supply flow is as follows: n is a radical of2The gas supply intensity of (A) is 0.06-0.07 Nm3Min. t, the gas supply intensity of Ar is 0.025-0.04 Nm3/min·t；
8) FeSi75 is adopted for deoxidation in the tapping process, and the adding amount is controlled according to the oxygen value at the end point of the converter, and the table is as follows:
9) and after tapping, blowing argon in an argon station for 3-5 min, and then sampling and conveying to a laboratory.
Compared with the prior art, the invention has the beneficial effects that:
the method controls the flow and the pressure of the bottom lance by the requirements on molten iron conditions during smelting of the combined blowing converter, the control of the unit consumption of the flux during smelting, the requirements on the combined blowing conditions and the control of the switching time of nitrogen and argon of the bottom lance, and the nitrogen content of the molten steel in the argon station of the converter can be over-stabilized within a certain range of 40ppm to 100ppm by the silicon deoxidation operation of the molten steel during tapping.
Detailed Description
The following describes in detail specific embodiments of the present invention.
A method for accurately controlling nitrogen increase of a combined blown converter comprises the following steps:
(1) the molten iron satisfies the following conditions: c: 4.2-4.5% Si: 0.3-0.6% Mn: 0.15-0.25% P: 0.060 to 0.085%. 0.001-0.005% of S, molten iron temperature: 1290-1330 ℃;
(2) the oxygen supply intensity of the converter is controlled to be 3.0-3.5 Nm3/min·t；
(3) The total addition amount of a flux in the converter smelting process is controlled to be 45-55 kg/t, and the flux comprises active lime and light-burned dolomite;
(4) the converter is provided with a sublance, and the oxygen supply intensity is controlled to be 1.8-2.1 Nm during TSC test of the sublance3/min·t；
(5) After the blowing begins, the movable smoke hood descends to a position 100-200 mm away from the furnace mouth;
(6) after the converter gas is recovered, controlling the micro-positive pressure of a converter mouth within the range of 0-20 Pa;
7) the number of converter bottom guns is 5-10, and the air supply flow, the switching time and the target nitrogen content of the bottom guns are as follows:
when the target nitrogen content is controlled to be 40-60 ppm, N is in the penultimate oxygen step of blowing2Switching to Ar till tapping is finished;
controlling the target nitrogen content between 61ppm and 80ppm, and N in the blowing TSC test2Switching to Ar till tapping is finished;
when the target nitrogen content is controlled to 81-100 ppm, N is added at the beginning of tapping2Switching to Ar till tapping is finished;
the target nitrogen content indicates the mass percentage of nitrogen elements in molten steel in a steel ladle after the steel is finished;
the air supply flow is as follows: n is a radical of2The gas supply intensity of (2) is 0.065Nm3Min. t, the gas supply intensity of Ar is 0.025-0.04 Nm3/min·t；
In particular, see the following table:
TABLE 1
In the above table:
the target nitrogen content is the mass percentage of nitrogen elements in molten steel in a steel ladle after tapping is finished; unit%;
the 'start of blowing' is the moment when the converter steelmaking starts to use an oxygen lance to blow oxygen to the molten pool;
the oxygen step is a certain time period of oxygen blowing of the converter, for example, from the beginning of blowing to the TSC test blowing for 10min, the oxygen step 2 is a blowing stage from 61s to 120s of blowing; the TSC test is a time period from the start of the TSC test to the end of the measurement; "blowing is finished" means the moment when the converter finishes smelting and closes oxygen to lift the oxygen lance; "TSO test" is the period of time from the beginning of measurement to the end of measurement of the sublance TSO; "tapping" refers to the period of time from the moment tapping is started to the moment tapping is finished.
8) FeSi75 is adopted for deoxidation in the tapping process, and the adding amount is controlled according to the oxygen value at the end point of the converter, and the table is as follows:
TABLE 2
In order to ensure the stability of the nitrogen content of the molten steel in the ladle after tapping, FeSi75 is added for deoxidation according to the oxygen value of the molten steel at the smelting end point in the tapping process, deoxidation alloy FeSi75 is stored in a middle alloy bin and added into the ladle through an alloy chute, the deoxidation alloy is added when the tapping amount reaches one third, and the addition amount is added according to the table 2.
9) And after tapping, blowing argon in an argon station for 3-5 min, and then sampling and conveying to a laboratory.
The method controls the flow and the pressure of the bottom lance by the requirements on molten iron conditions during smelting of the combined blowing converter, the control of the unit consumption of the flux during smelting, the requirements on the combined blowing conditions and the control of the switching time of nitrogen and argon of the bottom lance, and the nitrogen content of the molten steel in the argon station of the converter can be over-stabilized within a certain range of 40ppm to 100ppm by the silicon deoxidation operation of the molten steel during tapping. The control precision and hit rate of nitrogen content in refining procedures are improved for military steel and high-silicon content steel, and the nitrogen content of finished products can be stably controlled within a target range of +/-7 ppm.
Detailed description of the preferred embodiment 1
Smelting furnace number: 0061, steel grade: AGCL11, the smelting end point target nitrogen content is 40 ppm-60 ppm.
The molten iron condition is as follows: c: 4.3% Si: 0.38% Mn: 0.19% P: 0.069% S, 0.002% molten iron temperature 1295 ℃. The oxygen supply intensity of the converter is controlled to be 3.4Nm3Min. t. The total addition amount of the flux in the smelting process is controlled to be 47kg/t, and the flux comprises active lime and light-burned dolomite. The converter is provided with a sublance, and the oxygen supply intensity is controlled to be 1.9Nm during TSC test of the sublance3Min. t. After the blowing begins, the movable smoke hood descends to 190mm away from the furnace mouth. And after the converter gas is recovered, controlling the micro-positive pressure of a converter mouth at 15 Pa.
The number of bottom guns of the converter is 6, the blowing begins to an oxygen step 8, N2The gas supply intensity is 0.063Nm3Min. t; oxygen step 9 was switched to Ar with a gas supply intensity of 0.04Nm3The/min. t, the oxygen step 10, the blowing end and the TSO test all adopt 0.04Nm3The TSC test adopts 0.035Nm3The steel tapping adopts 0.025Nm3/min·t。
The final oxygen value is 532ppm, FeSi75 is adopted for deoxidation in the tapping process, the addition amount of FeSi75 is 0.25kg/t, after tapping is finished, argon is blown in an argon station for 4min, then a sample is taken and sent to a laboratory, and the nitrogen content of the test result is 54 ppm.
Specific example 2
Smelting furnace number: 0064, steel grade: AGCL13, the smelting end point target nitrogen content is 61 ppm-80 ppm.
The molten iron condition is as follows: c: 4.4% Si: 0.42% Mn: 0.21% P: 0.066% S, 0.002% molten iron temperature 1321 ℃. The oxygen supply intensity of the converter is controlled to be 3.4Nm3Min. t. Smelting processThe total addition amount of the fluxing agent in the smelting process is controlled to be 51kg/t, and the fluxing agent comprises active lime and light-burned dolomite. The converter is provided with a sublance, and the oxygen supply intensity is controlled to be 1.9Nm during TSC test of the sublance3Min. t. After the blowing begins, the movable smoke hood descends to 190mm away from the furnace mouth. And after the converter gas is recovered, controlling the micro-positive pressure of a converter mouth at 15 Pa.
The number of bottom guns of the converter is 6, the blowing begins to the oxygen step 10, N2The gas supply intensity is 0.065Nm3Min. t; the TSC test was switched to Ar with an air supply intensity of 0.035Nm3The/min. t, the blowing end and the TSO test are all 0.04Nm3The steel tapping adopts 0.025Nm3/min·t。
And the final oxygen value is 814ppm, FeSi75 is adopted for deoxidation in the tapping process, the addition amount of FeSi75 is 0.53kg/t, after tapping is finished, argon is blown in an argon station for 4.5min, then a sample is taken and sent to a laboratory, and the nitrogen content of the test result is 73 ppm.
Specific example 3
Smelting furnace number: 0075, steel grade: AGCL21, the smelting end point target nitrogen content is 81 ppm-100 ppm.
The molten iron condition is as follows: c: 4.4% Si: 0.45% Mn: 0.20% P: 0.078% S and 0.002% molten iron at 1321 ℃. The oxygen supply intensity of the converter is controlled to be 3.4Nm3Min. t. The total addition amount of the flux in the smelting process is controlled to be 53kg/t, and the flux comprises active lime and light-burned dolomite. The converter is provided with a sublance, and the oxygen supply intensity is controlled to be 1.9Nm during TSC test of the sublance3Min. t. After the blowing begins, the movable smoke hood descends to 190mm away from the furnace mouth. And after the converter gas is recovered, controlling the micro-positive pressure of a converter mouth at 15 Pa.
The number of converter bottom guns is 6, and N is blown uniformly from the beginning of blowing to the end of TSO test2TSC test, TSO test stage, N2The gas supply intensity is 0.035Nm3Min. t; other oxygen step N2The gas supply intensity is 0.068Nm3Min. t; at the beginning of tapping N2Switching to Ar with air supply intensity of 0.025Nm3/min·t。
FeSi75 is used for deoxidation in the tapping process, and the end point oxygen value is 759 ppm. FeSi75 is deoxidized and added with 0.49kg/t, after tapping, argon is blown in an argon station for 4min, then a sample is taken and sent to a laboratory, and the nitrogen content of the test result is 87 ppm.
The above embodiments are implemented on the premise of the technical solution of the present invention, and detailed embodiments and specific operation procedures are given, but the scope of the present invention is not limited to the above embodiments. The methods used in the above examples are conventional methods unless otherwise specified.
Claims (1)
1. A method for accurately controlling nitrogen increase of a combined blown converter is characterized by comprising the following steps:
1) the molten iron satisfies the following conditions: c: 4.2-4.5% Si: 0.3-0.6% Mn: 0.15-0.25% P: 0.060 to 0.085%, S0.001 to 0.005%, molten iron temperature: 1290-1330 ℃;
2) the oxygen supply intensity of the converter is controlled to be 3.0-3.5 Nm3/min·t；
3) The total addition amount of a flux in the converter smelting process is controlled to be 45-55 kg/t, and the flux comprises active lime and light-burned dolomite;
4) the oxygen supply intensity is controlled to be 1.8-2.1 Nm during the TSC test of the sublance3/min·t；
5) After the blowing begins, the movable smoke hood descends to a position 100-200 mm away from the furnace mouth;
6) after the converter gas is recovered, controlling the micro-positive pressure of a converter mouth within the range of 0-20 Pa;
7) the air supply flow of the bottom gun, the switching time and the target nitrogen content are as follows:
when the target nitrogen content is controlled to be 40-60 ppm, the oxygen blowing time period is divided into 10 oxygen steps, and N is in the penultimate oxygen step2Switching to Ar till tapping is finished;
controlling the target nitrogen content between 61ppm and 80ppm, and N in the blowing TSC test2Switching to Ar till tapping is finished;
when the target nitrogen content is controlled to 81-100 ppm, N is added at the beginning of tapping2Switching to Ar till tapping is finished;
the target nitrogen content indicates the mass percentage of nitrogen elements in molten steel in a steel ladle after the steel is finished;
the air supply flow is as follows: n is a radical of2The gas supply intensity of (A) is 0.06-0.07 Nm3Min. t, the gas supply intensity of Ar is 0.025-0.04 Nm3/min·t；
8) FeSi75 is adopted for deoxidation in the tapping process, and the adding amount is controlled according to the oxygen value at the end point of the converter, and the table is as follows:
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| Publication number | Priority date | Publication date | Assignee | Title |
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| ZA775918B (en) * | 1977-01-11 | 1978-05-30 | Nat Steel Corp | The use of orgon to prepare low-carbon,low-nitrogen steels in the basic oxygen process |
| CN102559983A (en) * | 2010-12-15 | 2012-07-11 | 鞍钢股份有限公司 | Method for preventing nitrogen increase of molten steel in converter tapping process |
| CN102230051B (en) * | 2011-06-16 | 2012-12-12 | 攀钢集团有限公司 | Method for controlling nitrogen content in steel by semi-steel smelting |
| CN102732665A (en) * | 2012-03-29 | 2012-10-17 | 鞍钢股份有限公司 | Method for increasing nitrogen in molten steel in last stage of converter smelting |
| CN105506214B (en) * | 2016-02-25 | 2017-10-03 | 攀钢集团攀枝花钢铁研究院有限公司 | A kind of method for improving converter tapping nitrogen content |
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