KR20100117228A - Method for refining molten steel in converter - Google Patents

Method for refining molten steel in converter Download PDF

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Publication number
KR20100117228A
KR20100117228A KR1020090035865A KR20090035865A KR20100117228A KR 20100117228 A KR20100117228 A KR 20100117228A KR 1020090035865 A KR1020090035865 A KR 1020090035865A KR 20090035865 A KR20090035865 A KR 20090035865A KR 20100117228 A KR20100117228 A KR 20100117228A
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KR
South Korea
Prior art keywords
slag
converter
low odor
port
flow rate
Prior art date
Application number
KR1020090035865A
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Korean (ko)
Inventor
조길동
Original Assignee
주식회사 포스코
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Priority to KR1020090035865A priority Critical patent/KR20100117228A/en
Publication of KR20100117228A publication Critical patent/KR20100117228A/en

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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
    • 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
    • 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
    • C21C5/36—Processes yielding slags of special composition
    • 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
    • C21C7/064—Dephosphorising; Desulfurising
    • 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
    • C21C7/068—Decarburising
    • 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
    • C21C2300/02—Foam creation

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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 present invention relates to a converter refining method applied to produce a high-purity high-grade steel, more specifically in the oxygen blowing in the upper portion of the converter 100 and the low odor gas blown in the bottom of the converter 100 in the converter 100 The first blow step of removing the molten iron and the slag intermediate exclusion step to exclude the slag formed on top of the converter 100 to the slag port 200 by tilting the converter 100, the slag intermediate exclusion step Reducing the flow rate of the low odor gas; Starting to tilt the converter (100) to exclude slag in the converter (100) as the slag port (200); And increasing the flow rate of the low odor gas when the tilt angle of the converter 100 becomes equal to or greater than a predetermined angle.

According to the present invention, by not only shortening the intermediate exclusion time of the slag after the first blow, but also increasing the exclusion amount, it is possible to obtain a practical effect of improving productivity, improving quality, and reducing cost.

Description

METHOD FOR REFINING MOLTEN STEEL IN CONVERTER}

The present invention relates to a converter refining method applied to produce high-clean high-grade steel, and more particularly, to a double slag operation method of refining molten steel in the converter twice.

In general, during the operation of the converter, scrap iron and molten iron are charged into the converter, pure oxygen is injected through the lance from the top to remove impurities from the molten iron, and when the refining operation is completed, the molten steel is pulled out in the ladle. However, as the production of low-grade high-grade steel has recently increased, steel grades for controlling phosphorus in the molten steel to 100 ppm or less have been derived, and in order to control phosphorus in the molten steel, a double slag operation is performed in which the molten steel is refined and pulled out twice in the converter.

Double slag operation takes place in the order of primary Tallin blow, intermediate rejection of slag, and secondary decarburization blow.

In the first Tallin drilling, scrap metal and molten iron are charged into the converter, and the molten iron is started to remove silicon and phosphorus from the molten iron. When the primary Tallinn blow is completed, the slag formed at the top of the converter is removed by tilting the converter as a slag port. Once the slag exclusion work is completed, the second decarburization is performed and the molten steel is pushed out to the ladle. However, the following problem occurs when the conventional exclusion work.

First, when the first Tallinn blow is completed, the slag is ejected into the furnace by slag forming. The slag ejection causes burnout of the converter furnace and the equipment installed under the furnace.

Second, when the slag is removed by tilting the converter with a tilting device, the converter must be slowly tilted to prevent sudden ejection of the slag by slag forming, which takes a long time. The tilting time from the establishment of the converter to the start of slag exclusion takes more than three minutes, which occupies about one third or more of the time when the slag is actually excluded.

Third, since the slag temperature after the first Tallinn blowing is more than 1350 degrees, if the slag is partially excluded from the slag port, carbon and oxide in the slag meet and react to increase the slag volume, resulting in the ejection of the slag into the upper portion of the slag port. Therefore, the surroundings of the rail which is the traveling path of the slag trolley | bogie are polluted, and a problem arises in the movement of trolley | bogie.

Fourth, since the slag in the slag port is not enough to exclude the slag in the converter, the amount of slag in the converter remains more than 1/2, the amount of auxiliary raw materials, such as quicklime added for basicity application and phosphorus control.

Fifth, when the slag amount increases, the slag temperature also increases when the molten steel is raised during refining, which causes deterioration of quality due to excessive generation due to insufficient heat source in the converter.

The present invention has been devised to solve the problems of the prior art, and provides an operation method for shortening the intermediate exclusion time of slag and increasing the exclusion amount through improvement of the control method of uptake and low odor after the first blow.

According to a first aspect of the present invention for achieving the above object, the first blowing step of blowing oxygen in the upper portion of the converter and the low odor gas in the bottom of the converter to delineate the molten iron in the converter, and the converter by tilting the converter And a slag intermediate elimination step of eliminating the slag formed on the upper portion of the slag port, wherein the slag intermediate elimination step includes: reducing a flow rate of the low odor gas; Starting to tilt the converter to exclude slag in the converter as the slag port; And increasing the flow rate of the low odor gas when the tilt angle of the converter is equal to or greater than a predetermined angle.

According to a second aspect of the present invention, the slag intermediate elimination step further includes the step of injecting a sedative into the slag port and spraying coolant when the slag rises to a predetermined point of the slag port.

According to the third aspect of the present invention, in the step of reducing the flow rate of the low odor gas, the flow rate of the low odor gas is reduced to 6 Nm 3 / min or less.

According to a fourth aspect of the present invention, in the step of increasing the flow rate of the low odor gas, the flow rate of the low odor gas is increased to 25 Nm 3 / min or more.

According to a fifth aspect of the invention, the predetermined angle is 55 degrees.

According to a sixth aspect of the invention, the predetermined point is two thirds of the slag port.

According to a seventh aspect of the present disclosure, the slag intermediate elimination step may further include a step of tilting the converter inversely when the tilt angle of the converter is 105 degrees.

According to the present invention, in the case of double slag operation, by not only shortening the intermediate exclusion time of the slag after the first blow, but also increasing the exclusion amount, it is possible to obtain a practical effect of improving productivity, improving quality, and reducing cost.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a system diagram of a slag intermediate exclusion apparatus according to an embodiment of the present invention. Referring to FIG. 1, a lance 110 is installed at an upper portion of the converter 100 to inject oxygen, and a lower odor nozzle 120 is installed at a bottom of the converter 100 to blow in a low odor gas. The low blowing gas blown in is inert gas, such as argon and nitrogen.

In addition, the converter 100 is provided with a tilt device 130 for tilting the converter 100 and a tilt goniometer 132 for detecting the tilt angle of the converter 100.

The slag port limit 220 is installed in the slag port 200, and the slag port limit 220 is detected by the standby limit 222 installed in the standby position to detect whether the slag port 200 is in the standby position. In addition, it is detected by the know-how limit 224 installed in the know-how position to detect whether the slag port 200 is in the know-how position. These limits can be configured magnetically. The slag port 200 can reciprocate between the standby position and the furnace position. When the slag port 200 is in the furnace position, the slag in the converter may be excluded as the slag port 200 through the converter furnace port formed in the converter 100 by tilting the converter 100.

In the vicinity of the slag position of the slag port 200, the slag position detection device 160 for detecting the slag position in the slag port 200, the sedative to inject the sedative into the slag port 200 to calm the slag according to the slag position The injection device 140 and a coolant spray nozzle 150 for spraying coolant to the slag to calm the slag foam according to the slag position are installed. As a sedative, you can use sedatives made of lime or paper pulp.

On the other hand, the above components, that is, the lance 110, the lower nozzle 120, the tilting device 130, the tilting goniometer 132, the slag port limit 220, the atmospheric limit 222, the no-limit limit 224, The sedative injection device 140, the coolant injection nozzle 150, and the slag position detection device 160 are all connected to the control device 300, and their operation is controlled by the control device 300.

Hereinafter, the control method of the slag intermediate exclusion apparatus comprised as mentioned above is demonstrated.

2 is a diagram showing the operational flow of the slag intermediate exclusion apparatus. Referring to FIG. 2, the slag port 200 in the standby position at the time of the primary Tallinn blowing moves to the lowering position (S1). When the slag port 200 is in the knowing position, the knowing limit 224 detects this and sends a signal to the control device 300, it can be confirmed that the slag port 200 is in the knowing position.

When the primary Tallinn blow is completed, the control device 300 sends a signal to the lance 110 to inject oxygen into the furnace at 18 bar and ascends the upper side of the converter 100, and simultaneously sends a signal to the low-odor nozzle 120. The low odor flow rate is controlled to blow below 6 Nm 3 / min (N means standard volume) (S2). The low odor flow rate during the first Tallinn drilling is 25 ~ 35 Nm 3 / min, which is lowered to 6Nm 3 / min or less.Also, the supersonic oxygen is injected into the converter 100 to reduce the slag foam that has risen to the furnace 100. do. If the low odor flow rate is maintained at a value greater than 6 Nm 3 / min, the slag foam is not sufficiently reduced, and the slag is ejected into the converter 100 furnace, resulting in burnout of the equipment installed in the furnace furnace and the furnace. In order to prevent sudden blowdown, the converter needs to be tilted slowly, which takes a long time. On the other hand, the lance 110 is prepared to tilt the converter 100 by raising it upward.

When the lance 110 rises to the upper standby position, the tilting device 130 tilts the converter 100 toward the slag port 200 at the lowering position to remove the slag (S3). At this time, the tilt goniometer 132 detects the tilt angle of the converter 100.

The tilt goniometer 132 detects when the tilt angle of the converter 100 reaches 55 degrees and sends a signal to the control device 300. The control device 300 that receives the signal has a low odor flow rate of 25 Nm 3 / min or more. The lower nozzle 120 is controlled so as to (S4). When the low odor flow rate is increased to 25 Nm 3 / min or more, the molten steel at the charging side of the converter 100 is circulated, and oxygen and carbon in the molten steel react to increase the slag foam by the CO gas. The increased slag foam allows for the rapid rejection of as much slag as possible. On the other hand, if the low odor flow rate is kept less than 25 Nm 3 / min, slag foam is not sufficiently generated, making it difficult to remove the slag efficiently, and the slag that is not excluded remains in the converter 100. On the other hand, it is preferable to increase the low odor flow rate to 25 Nm 3 / min or more when the tilt angle of the converter 100 becomes 55 degrees. This is because, when the tilt angle is smaller than 55 degrees, the slag foam may flow into the converter 100 furnace port as the initial state of the slag removal operation as the initial state of the low odor flow rate.

As the slag is excluded in the slag port 200, the slag position detecting device 160 detects the position of the slag in the slag port 200, and when the slag comes up to 2/3 of the slag port 200, the slag is raised. The position sensing device 160 detects this and sends a signal to the control device 300. The control device 300 receiving the signal causes the sedative injector 140 to inject the sedative into the slag port 200, and simultaneously controls the coolant injection nozzle 150 to inject the coolant to the slag in the slag port 200. do. The slag foam is reduced by injecting a sedative into the slag port 200 and spraying the coolant. When the slag does not reach the 2/3 point of the slag port 200, there is no fear that the slag is ejected to the upper portion of the slag port 200, but when the slag rises to the 2/3 point, the slag is the upper part of the slag port 200 It is possible to reduce slag foam with sedatives and coolant because it can be ejected. Therefore, the phenomenon of slag overflowing to the upper portion of the slag port 200 can be prevented and the slag in the converter 100 can be sufficiently excluded.

By tilting the converter 100, the slag is continuously excluded from the slag port 200, and when the tilt angle of the converter 100 is 105 degrees, the tilt angle meter 132 detects this and sends a signal to the control device 300. The control device 300 receiving this signal establishes the converter 100 as the tilt device 130 and completes the exclusion work (S5). This is because molten steel in the converter 100 may flow out when the tilt angle is 105 degrees or more.

Hereinafter, the effects of the present invention through the examples.

Exclusion time (minutes) Steelmaking time Exclusion Amount (t) Quicklime input in 2nd decarburization (kg) Conventional Example 1 8.5 42.5 5 6000 Conventional Example 2 8 42 4 6500 Conventional Example 3 9 43.5 5 6000 Inventive 1 3.8 36 12 5000 Inventive 2 4 35 10 5500 Inventive 3 3.9 36 11 4500

In the conventional example, the exclusion time was longer than 8 minutes, and the steelmaking time (the time of steelmaking was the first time of the primary refining, the intermediate elimination of the slag, and the secondary refining as the whole process) was also taken for 42 minutes or more. This is because the decarburization time is delayed. In addition, the exclusion amount was only about 5t in the conventional example.

However, in the present invention, the exclusion time is shortened to less than 4 minutes, the steelmaking time is also shortened to less than 36 minutes, and also the exclusion amount is 10t or more, and the amount of quicklime added during the second decarburization is reduced by 1t or more compared with the conventional example. You can check it.

1 is a system diagram of a slag intermediate exclusion apparatus according to an embodiment of the present invention.

2 is a diagram showing the operating flow of the slag intermediate exclusion device according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100 converter 110 lance

120 odor nozzle 130 tilt device

132 Tilt Tilt Meter 140 Sedative Dispenser

150 Coolant jet nozzle 160 Slag position detector

200 slag port 220 slag port limit

222 Waiting Limit 224 Noha Limit

300 control unit

Claims (7)

The primary blowing step of blowing oxygen into the converter 100 and blowing the low odor gas to the bottom of the converter 100 to desalinate the molten iron in the converter 100, and tilting the converter 100 to upper part of the converter 100. Including a slag intermediate exclusion step for excluding the slag formed in the slag port 200, The slag intermediate exclusion step, Reducing the flow rate of the low odor gas; Starting to tilt the converter (100) to exclude slag in the converter (100) as the slag port (200); And When the tilt angle of the converter 100 is more than a predetermined angle increasing the flow rate of the low odor gas Converter refining method to include. The method according to claim 1, The slag intermediate elimination step further comprises the step of injecting a sedative into the slag port (200) when the slag rises to a predetermined point of the slag port (200) and spraying the coolant. The method according to claim 1 or 2, A converter refining method for reducing the flow rate of the low odor gas to 6 Nm 3 / min or less in the step of reducing the flow rate of the low odor gas. The method according to claim 1 or 2, A converter refining method for increasing the flow rate of the low odor gas to 25 Nm 3 / min or more in increasing the flow rate of the low odor gas. The method according to claim 1 or 2, And said predetermined angle is 55 degrees. The method according to claim 2, The predetermined point is two thirds of the slag port (200). The method according to claim 1 or 2, The slag intermediate exclusion step, the converter refining method further comprises the step of tilting the converter (100) in reverse when the tilting angle of the converter (100) is 105 degrees.
KR1020090035865A 2009-04-24 2009-04-24 Method for refining molten steel in converter KR20100117228A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20160060847A (en) 2014-11-20 2016-05-31 주식회사 포스코 Convertor and the refining method of molten steel using it
KR101660774B1 (en) 2015-07-09 2016-09-28 주식회사 포스코 The converter operation method
KR101663949B1 (en) 2015-07-14 2016-10-12 주식회사 포스코 Blowing method of converter
KR101709137B1 (en) 2015-08-13 2017-02-23 주식회사 포스코 The converter operation method
JP2022089776A (en) * 2020-12-04 2022-06-16 Ｊｆｅスチール株式会社 Method for suppressing slag foaming, sedative projection nozzle, and sedative projection device

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20160060847A (en) 2014-11-20 2016-05-31 주식회사 포스코 Convertor and the refining method of molten steel using it
KR101660774B1 (en) 2015-07-09 2016-09-28 주식회사 포스코 The converter operation method
KR101663949B1 (en) 2015-07-14 2016-10-12 주식회사 포스코 Blowing method of converter
KR101709137B1 (en) 2015-08-13 2017-02-23 주식회사 포스코 The converter operation method
JP2022089776A (en) * 2020-12-04 2022-06-16 Ｊｆｅスチール株式会社 Method for suppressing slag foaming, sedative projection nozzle, and sedative projection device

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