CN113337677A - Method for further decarbonizing converter molten steel after tapping and in LF (ladle furnace) process - Google Patents
Method for further decarbonizing converter molten steel after tapping and in LF (ladle furnace) process Download PDFInfo
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- CN113337677A CN113337677A CN202110515492.8A CN202110515492A CN113337677A CN 113337677 A CN113337677 A CN 113337677A CN 202110515492 A CN202110515492 A CN 202110515492A CN 113337677 A CN113337677 A CN 113337677A
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- Prior art keywords
- molten steel
- steel
- converter
- tapping
- ladle
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 126
- 239000010959 steel Substances 0.000 title claims abstract description 126
- 238000000034 method Methods 0.000 title claims abstract description 47
- 238000010079 rubber tapping Methods 0.000 title claims abstract description 37
- 230000008569 process Effects 0.000 title claims abstract description 24
- 238000009847 ladle furnace Methods 0.000 title abstract description 23
- 239000002893 slag Substances 0.000 claims abstract description 22
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 18
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 18
- 238000007664 blowing Methods 0.000 claims abstract description 15
- 238000006243 chemical reaction Methods 0.000 claims abstract description 11
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000001301 oxygen Substances 0.000 claims abstract description 8
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 8
- 238000005275 alloying Methods 0.000 claims abstract description 5
- 239000007789 gas Substances 0.000 claims abstract description 4
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 38
- 229910052786 argon Inorganic materials 0.000 claims description 19
- 238000005261 decarburization Methods 0.000 claims description 14
- 238000003723 Smelting Methods 0.000 claims description 12
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 7
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 7
- 230000005540 biological transmission Effects 0.000 claims description 7
- 238000010438 heat treatment Methods 0.000 claims description 7
- 239000004571 lime Substances 0.000 claims description 7
- 238000003756 stirring Methods 0.000 claims description 4
- 230000009471 action Effects 0.000 claims description 3
- 239000002436 steel type Substances 0.000 claims description 2
- 239000006260 foam Substances 0.000 description 7
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 3
- 238000005262 decarbonization Methods 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 238000005187 foaming Methods 0.000 description 3
- 238000009628 steelmaking Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- CSJDCSCTVDEHRN-UHFFFAOYSA-N methane;molecular oxygen Chemical compound C.O=O CSJDCSCTVDEHRN-UHFFFAOYSA-N 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000009991 scouring Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 239000002699 waste material Substances 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
- 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
- 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
-
- 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
- C21C7/072—Treatment with gases
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
Abstract
The invention discloses a method for further decarbonizing converter molten steel after tapping and an LF (ladle furnace) process, which is characterized in that the molten steel smelted by a converter does not undergo deoxidation alloying after the converter tapping enters a ladle, a certain amount of slag charge is added in the tapping process, then the molten steel is transmitted through an LF (ladle furnace) and stirred by blowing gas at the bottom of the ladle, the slag-steel interface reaction between slag and the molten steel is increased, and carbon elements in the molten steel are further oxidized by using oxygen in the molten steel, so that the aim of further decarbonizing the converter molten steel after the converter tapping is fulfilled.
Description
Technical Field
The invention relates to the technical field of metallurgy, in particular to a method for continuously decarbonizing molten steel smelted by a converter after tapping and in an LF (ladle furnace) process, which overcomes the defect that low-carbon steel smelting is difficult due to insufficient decarbonization capability of the converter.
Background
With the development of steel-making technology, converter steel-making has become one of the main means of steel-making production in the world today. The service life of the converter lining of the converter is greatly prolonged, and the service life of the converter lining of one time of service is even more than 2 ten thousand furnaces. In the later stage of the converter campaign, because the converter lining is influenced by a plurality of factors, the furnace type is not regular any more, and simultaneously the firebrick of the working layer body of the lining has corroded to the later stage, so the limited factor of the blowing process is more, the decarburization is difficult to occur frequently, and even waste products appear because the decarburization of the converter cannot meet the requirement of smelting steel varieties.
Disclosure of Invention
The invention aims to provide a method for continuously decarbonizing converter molten steel after converter tapping and in an LF (ladle furnace) process, which can realize a continuous decarbonization process after the converter molten steel is subjected to converter tapping, effectively solves the defects of difficult decarbonization in the later service period of a converter and low qualified rate of smelting low-carbon steel, and is simple to operate, convenient and practical.
In order to achieve the purpose, the invention adopts the technical scheme that:
a method for further decarbonizing molten steel of a converter after tapping and an LF process is characterized in that the molten steel smelted by the converter does not undergo deoxidation alloying after the molten steel of the converter enters a steel ladle after the steel tapping of the converter, a certain amount of slag charge is added in the steel tapping process, then the molten steel is subjected to power transmission through an LF furnace and gas stirring at the bottom of the steel ladle, the slag-steel interface reaction between the slag and the molten steel is increased, and carbon elements in the molten steel are further oxidized by using oxygen in the molten steel, so that the purpose of further decarbonizing the molten steel smelted by the converter after the steel tapping of the converter is realized, and the method specifically comprises the following steps:
firstly, the end point carbon content of molten steel smelted by a converter is 0.03-0.06 wt%, the end point oxygen content of the converter is 0.0500-0.1000 wt%, and other elements are controlled according to the requirements of the steel grade;
secondly, opening a steel ladle bottom to blow argon 2min before tapping of the converter, removing air in the steel ladle, adding lime into the steel ladle along with the steel flow when one third of the converter tapping is performed, and opening the steel ladle bottom to blow argon in the whole process during tapping to ensure that molten steel is turned over and oxygen and carbon in the molten steel continue to react to decarburize;
thirdly, after the molten steel enters the LF procedure, the molten steel is subjected to power transmission heating, and meanwhile, the stirring action of blowing argon from the bottom of a steel ladle is matched, so that the slag-steel interface reaction is accelerated, the slag is foamed, and the further molten steel decarburization reaction is realized;
and fourthly, according to the requirement of carbon content of the smelting molten steel, when the carbon content of the molten steel enters a smelting target, carrying out deoxidation alloying in LF according to the requirement of the steel type to be smelted, and smelting in the next procedure.
Preferably, the lime is added into the molten steel along with the steel flow in an amount of 0.6kg-3kg per ton of steel during the tapping process of the second converter, so that the lime is completely dissolved.
Preferably, in the second step, the ladle bottom blowing argon is opened in the whole process of tapping from the converter, and the argon flow is 500-800 NL/min.
Preferably, in the third step, after the LF procedure is carried out, the molten steel is subjected to power transmission heating, the heating time is 2-5min each time, the flow is controlled to be 800NL/min by matching with the blowing of argon at the bottom of the steel ladle, and the adjustment is carried out according to the foaming state of the slag.
Preferably, after the molten steel enters the steel ladle from the converter, the height (free space) between the liquid level of the molten steel in the steel ladle and the upper opening of the steel ladle is 500-1000mm, so that a certain foaming space of the slag is ensured in the carbon-oxygen reaction process.
Preferably, after the molten steel enters the ladle from the converter, the molten steel is subjected to impact and stirring action of steel flow during tapping so as to be subjected to subsequent decarburization on an LF slag-steel interface, and the reaction equation is [ C ] + [ O ] = [ CO ], and slag is foamed due to gas generated by reaction.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention realizes the purpose of adopting LF to continue decarburization after molten steel is discharged from the converter, and can effectively solve the defect that carbon in the molten steel cannot be decarburized to the target requirement in the later period of the service of the converter due to the fact that the furnace type is not regular any more and blowing decarburization is difficult.
2. The method can effectively solve the adverse effects of excessive oxidation, scouring, corrosion and the like of the furnace lining of the converter caused by forcibly blowing the low-carbon steel, is favorable for stabilizing the furnace type of the converter and improving the furnace life.
3. When the LF continues to decarbonize, compared with a converter, the LF has more flexible functions of heating, measuring temperature, sampling and the like on the molten steel, can more accurately control the carbon content in the molten steel, and ensures that the carbon content in the molten steel meets the target requirement.
Detailed Description
The technical solutions and effects of the present invention will be further described with reference to specific examples, but the scope of the present invention is not limited thereto.
Example 1
In this example, the present invention is explained by taking the case where decarburization is continued in an argon station and an early stage of LF smelting after tapping from a 150t converter.
The 150t converter has the service life of a 12565 furnace, the furnace type is not regular any more, and the laser thickness gauge shows that the part with the thinnest working layer refractory is 350mm (including a splash layer), and in the actual production, the 150t converter is difficult to decarbonize the molten steel to be below 0.035 wt%.
The tapping amount of a 150t converter is 155t-165t, when the converter is blown to the end point, a molten steel sample 1 is taken, the carbon content at the end point of the converter is 0.035-0.060 wt%, the oxygen at the end point is 0.0500-0.0800 wt%, during tapping, when the molten steel is discharged to 30-40t, 200kg of lime (1.2-1.3 kg of added amount of steel per ton) is added into the molten steel along with the steel flow direction, the argon blowing flow at the bottom of the steel ladle during tapping is 600NL/min, the molten steel surface is overturned to be disc-shaped, and after the tapping is finished and stirred for 2-3min, a molten steel sample 2 is taken;
and (2) the molten steel enters LF, slag breaking and power transmission heating are firstly carried out for 3-5min, argon blowing at the bottom of a steel ladle is properly adjusted, argon blowing at the bottom of a double-hole bottom is 300-NL/min, when power transmission is stopped for 1-2min, the slag starts to foam, the foaming state of the slag is observed at the moment, when the foam slag approaches the upper opening of the steel ladle, the argon is immediately reduced to 300 NL/min (the actual flow is about 200-300 NL/min), the foam slag sinks, the argon blowing flow at the bottom of the steel ladle is properly adjusted, a certain safety distance between the foam slag and the upper opening of the steel ladle is ensured, the slag can be fully foamed, the foam slag has an obvious descending trend after the foam slag starts to grow for about 10min, and the molten steel sample 3 is obtained after the foam slag is uniformly stirred again.
After the 3-component test of the molten steel sample, if the carbon content of the molten steel does not meet the target requirement (the carbon is less than or equal to 0.035wt% in the smelting process), continuously transmitting electricity to heat for 3-5min, adjusting the argon blowing at the bottom of the steel ladle, further promoting the carbon-oxygen reaction to proceed, and then the slag can be foamed again.
The data of the 15-furnace steel smelting process by the method are shown in the table 1.
As can be seen from Table 1, in the 14-furnace steel smelted by the method disclosed by the invention, after the molten steel is tapped from the converter, the continuous decarburization process is stable, the decarburization is obvious, the molten steel is decarburized to be below 0.035wt%, and the finished product completely meets the requirement of the target carbon of 0.028-0.038 wt%.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (5)
1. A method for further decarbonizing molten steel of a converter after tapping and an LF procedure is characterized in that the method is that the molten steel smelted by the converter does not undergo deoxidation alloying after the molten steel of the converter enters a steel ladle after the steel tapping of the converter, a certain amount of slag charge is added in the steel tapping process, then the molten steel is transmitted through an LF furnace, gas is blown from the bottom of the steel ladle and stirred, the slag-steel interface reaction between slag and the molten steel is increased, and carbon elements in the molten steel are further oxidized by using oxygen in the molten steel, so that the purpose of further decarbonizing the molten steel smelted by the converter after the steel tapping of the converter is realized, and the method specifically comprises the:
firstly, the end point carbon content of molten steel smelted by a converter is 0.03-0.06 wt%, the end point oxygen content of the converter is 0.0500-0.1000 wt%, and other elements are controlled according to the requirements of the steel grade;
secondly, opening a steel ladle bottom to blow argon 2min before tapping of the converter, removing air in the steel ladle, adding lime into the steel ladle along with the steel flow when one third of the converter tapping is performed, and opening the steel ladle bottom to blow argon in the whole process during tapping to ensure that molten steel is turned over and oxygen and carbon in the molten steel continue to react to decarburize;
thirdly, after the molten steel enters the LF procedure, the molten steel is subjected to power transmission heating, and meanwhile, the stirring action of blowing argon from the bottom of a steel ladle is matched, so that the slag-steel interface reaction is accelerated, the slag is foamed, and the further molten steel decarburization reaction is realized;
and fourthly, according to the requirement of carbon content of the smelting molten steel, when the carbon content of the molten steel enters a smelting target, carrying out deoxidation alloying in LF according to the requirement of the steel type to be smelted, and smelting in the next procedure.
2. The method for further decarburization of the converter molten steel after tapping and in the LF process as recited in claim 1, wherein lime is added to the molten steel in the second converter tapping process in an amount of 0.6kg to 3kg per ton of steel, and is added to the molten steel as the steel flows, so that the lime is completely melted.
3. The method for further decarburization of molten steel in a converter after tapping and in an LF process as recited in claim 1, wherein in the second step, the ladle bottom blowing argon is opened all the time during tapping of the converter, and the flow rate of argon is 500-800 NL/min.
4. The method for further decarburization of the converter molten steel after tapping and in the LF process as claimed in claim 1, wherein in the third step, after entering the LF process, the molten steel is heated by power transmission, each heating time is 2-5min, and the flow rate is 300-800NL/min in cooperation with argon blowing from the bottom of the ladle.
5. The method for further decarburization of the molten steel in the converter after tapping and in the LF process as recited in claim 1, wherein the height of the molten steel level in the ladle from the ladle upper opening after the molten steel enters the ladle from the converter is 500-1000 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110515492.8A CN113337677A (en) | 2021-05-12 | 2021-05-12 | Method for further decarbonizing converter molten steel after tapping and in LF (ladle furnace) process |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110515492.8A CN113337677A (en) | 2021-05-12 | 2021-05-12 | Method for further decarbonizing converter molten steel after tapping and in LF (ladle furnace) process |
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| Publication Number | Publication Date |
|---|---|
| CN113337677A true CN113337677A (en) | 2021-09-03 |
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|---|---|---|---|
| CN202110515492.8A Pending CN113337677A (en) | 2021-05-12 | 2021-05-12 | Method for further decarbonizing converter molten steel after tapping and in LF (ladle furnace) process |
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| Country | Link |
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| CN (1) | CN113337677A (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102367503A (en) * | 2011-10-31 | 2012-03-07 | 首钢总公司 | Method for controlling contents of phosphorus, sulfur and hydrogen in molten steel |
| CN106957941A (en) * | 2017-03-13 | 2017-07-18 | 唐山钢铁集团有限责任公司 | Utilize the method for RH decarburization smelting low carbon steel alloys |
| JP2018066030A (en) * | 2016-10-17 | 2018-04-26 | 新日鐵住金株式会社 | Manufacturing method of high cleanliness steel |
| CN108330251A (en) * | 2018-05-22 | 2018-07-27 | 湖南华菱湘潭钢铁有限公司 | Process for decarbonizing after a kind of Converter |
-
2021
- 2021-05-12 CN CN202110515492.8A patent/CN113337677A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102367503A (en) * | 2011-10-31 | 2012-03-07 | 首钢总公司 | Method for controlling contents of phosphorus, sulfur and hydrogen in molten steel |
| JP2018066030A (en) * | 2016-10-17 | 2018-04-26 | 新日鐵住金株式会社 | Manufacturing method of high cleanliness steel |
| CN106957941A (en) * | 2017-03-13 | 2017-07-18 | 唐山钢铁集团有限责任公司 | Utilize the method for RH decarburization smelting low carbon steel alloys |
| CN108330251A (en) * | 2018-05-22 | 2018-07-27 | 湖南华菱湘潭钢铁有限公司 | Process for decarbonizing after a kind of Converter |
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