CN116716450A - Low silicon steel smelting method - Google Patents
Low silicon steel smelting method Download PDFInfo
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- CN116716450A CN116716450A CN202310682159.5A CN202310682159A CN116716450A CN 116716450 A CN116716450 A CN 116716450A CN 202310682159 A CN202310682159 A CN 202310682159A CN 116716450 A CN116716450 A CN 116716450A
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- 238000000034 method Methods 0.000 title claims abstract description 80
- 238000003723 Smelting Methods 0.000 title claims abstract description 51
- 229910000976 Electrical steel Inorganic materials 0.000 title claims abstract description 38
- 239000002893 slag Substances 0.000 claims abstract description 122
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 84
- 239000010959 steel Substances 0.000 claims abstract description 84
- 238000010079 rubber tapping Methods 0.000 claims abstract description 72
- 230000008569 process Effects 0.000 claims abstract description 48
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 39
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 39
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 32
- 238000007670 refining Methods 0.000 claims abstract description 32
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 23
- 229910000914 Mn alloy Inorganic materials 0.000 claims abstract description 11
- 229910052742 iron Inorganic materials 0.000 claims abstract description 11
- 239000008188 pellet Substances 0.000 claims abstract description 11
- 238000005261 decarburization Methods 0.000 claims abstract description 9
- 238000009792 diffusion process Methods 0.000 claims abstract description 7
- 238000003756 stirring Methods 0.000 claims description 40
- 238000007664 blowing Methods 0.000 claims description 37
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 13
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 13
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 13
- 239000004571 lime Substances 0.000 claims description 13
- 238000007599 discharging Methods 0.000 claims description 4
- 229910052710 silicon Inorganic materials 0.000 abstract description 26
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 abstract description 25
- 239000010703 silicon Substances 0.000 abstract description 25
- 238000009749 continuous casting Methods 0.000 abstract description 21
- 238000004519 manufacturing process Methods 0.000 description 13
- 230000000903 blocking effect Effects 0.000 description 11
- 229910052799 carbon Inorganic materials 0.000 description 8
- 239000007789 gas Substances 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 6
- 230000001590 oxidative effect Effects 0.000 description 6
- 239000002245 particle Substances 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- CSJDCSCTVDEHRN-UHFFFAOYSA-N methane;molecular oxygen Chemical compound C.O=O CSJDCSCTVDEHRN-UHFFFAOYSA-N 0.000 description 5
- 230000003647 oxidation Effects 0.000 description 5
- 238000007254 oxidation reaction Methods 0.000 description 5
- 230000009467 reduction Effects 0.000 description 5
- 229910004298 SiO 2 Inorganic materials 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 241001062472 Stokellia anisodon Species 0.000 description 3
- 230000002349 favourable effect Effects 0.000 description 3
- 238000005187 foaming Methods 0.000 description 3
- 239000011572 manganese Substances 0.000 description 3
- 229910052717 sulfur Inorganic materials 0.000 description 3
- 229910000838 Al alloy Inorganic materials 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000003009 desulfurizing effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 229910001021 Ferroalloy Inorganic materials 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
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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
-
- 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
- C21C7/0006—Adding metallic additives
-
- 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
- C21C7/0025—Adding carbon material
-
- 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
-
- 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
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- 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)
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- Metallurgy (AREA)
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- Carbon Steel Or Casting Steel Manufacturing (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
The invention discloses a low silicon steel smelting method, which comprises the following steps: (1) Charging the pretreated molten iron into a converter, adopting double slag operation in the smelting process, pouring out a part of desilication slag after desilication is finished, reconstructing new slag for decarburization, and controlling the alkalinity of the converter slag; (2) Tapping in a converter, adding carbon powder into a ladle for pre-deoxidization, and adding manganese alloy and aluminum pellets into the ladle for deep deoxidization when tapping reaches a certain degree; (3) Molten steel is filled into an LF furnace, carbon powder is adopted for diffusion deoxidation on the slag surface, and high-alkalinity refining slag is produced in the refining process. The smelting method can effectively avoid exceeding of silicon content of molten steel in the smelting process and smoothly realize continuous casting of molten steel.
Description
Technical Field
The invention relates to the technical field of steelmaking, in particular to a low-silicon steel smelting method.
Background
Preventing the silicon increase of molten steel is a very important problem in the production of steel grades with a low silicon content. When the steel is produced, the silicon content in the steel is required to be less than or equal to 0.03 percent, if the phenomenon that the silicon content exceeds the standard occurs, the steel grade is changed, and even the furnace is returned for casting, so that great problems are brought to the production organization of enterprises.
The production process of the low-silicon steel is generally converter-LF furnace-continuous casting. The molten steel is required to be deoxidized at the refining furnace site, and the deoxidizers are generally classified into silicon deoxidizers and aluminum deoxidizers. Because of the production of low silicon steel, aluminum deoxidizers are generally used in the production of low silicon steel. However, the aluminum deoxidizer is a strong deoxidizer and can be used for mixing SiO in the refining slag 2 The Si element generated is reduced into molten steel so as to lead the silicon content of the molten steel to exceed the standard, and Al is generated by aluminum deoxidation 2 O 3 The inclusion can cause continuous casting water blocking when the rear part is removed insufficiently, and the continuous casting heat is affected.
The silicon in the molten steel at the end of converter blowing is basically trace ([ Si)]< 0.001%) in converter slag (Si 0) 2 ) The content is 15-20%, the tapping slag is not good, and slag making materials and ferroalloy inevitably carry a certain amount of silicon, so that the silicon content of the ladle top slag is enriched, and when the subsequent molten steel deoxidizes, slag making, desulfurizing and impurity removing refining are carried out, the content of (Si 0 in the ladle top slag 2 ) Is easily reduced into [ Si ] by strong reducing agent such as aluminum]Entering molten steel to cause silicon increase of the molten steel, which causes contradiction between deoxidation, desulfurization, slag inclusion control and silicon increase of the molten steel when low silicon steel is produced, and prevents silicon increase in the whole smelting process from becoming the bottleneck of smelting low silicon variety steel. To break through the restrictive bottleneckThe control process for preventing silicon increase in the smelting process and stable silicon content at the continuous casting end point is an urgent problem to be solved.
Disclosure of Invention
In order to solve the problems, the invention aims to provide a low-silicon steel smelting method.
Specifically, the invention is realized by the following technical scheme:
a low silicon steel smelting method comprises the following steps:
(1) Charging the pretreated molten iron into a converter, adopting double slag operation in the smelting process, pouring out a part of desilication slag after desilication is finished, reconstructing new slag for decarburization, and controlling the alkalinity of the converter slag;
(2) Tapping in a converter, adding carbon powder into a ladle for pre-deoxidization, and adding manganese alloy and aluminum pellets into the ladle for deep deoxidization when tapping reaches a certain degree;
(3) Molten steel enters an LF furnace, carbon powder is adopted for diffusion deoxidation on the slag surface, and high-alkalinity refining slag is produced in the refining process.
Optionally, in the step (1), the deslagging amount after desilication is 40% -60%.
Optionally, in step (1), the alkalinity of the converter slag is controlled to be 3.5 to 4.5.
Optionally, in step (1), before the end of the converter smelting, tapping, [ C ] is controlled]﹒[O]Less than or equal to 0.0016, according to 0.15 to 0.20Nm 3 Air supply intensity bottom blowing CO of/(min × t) 2 Stirring for 1.5-2.5 min.
Optionally, in the step (2), converter tapping adopts double slag blocking operation of a slag blocking cone and a sliding plate slag blocking, and the slag thickness of the slag is less than 30mm.
Optionally, in the step (2), adding carbon powder into the ladle according to the amount of 0.2-0.3 kg/t; and (3) adding manganese alloy and aluminum pellets for deep deoxidization when tapping 2/3, and ensuring that the aluminum pellets are completely added when tapping in the converter.
Optionally, in the step (2), lime is added according to 5-6 kg/t when the converter is tapped, and slag is formed by utilizing tapping steel flow impact; after tapping of the converter, stirring for 2-3 min by high-flow bottom blowing.
Optionally, in the step (3), the dosage of the carbon powder is 15-30 kg/furnace, and the components of the high-alkalinity refining slag are as follows: caO 50-60%, siO 2 8％～12％，Al 2 O 3 20％～30％，MgO 6％～8％。
Optionally, in the step (3), the bottom blowing intensity adopted by bottom blowing stirring in the refining process is 200-400L/min.
Optionally, in the step (3), soft stirring is carried out before tapping, the bottom blowing strength is 50-100L/min, and the soft stirring time of molten steel is more than 10min.
According to the technical scheme, the low-silicon steel smelting method has at least the following beneficial effects:
1. the smelting method of the invention produces high alkalinity furnace slag through double slag operation of the converter, and reduces (SiO 2 ) The content of the aluminum alloy is reduced, the converter tapping adopts double slag blocking operation, the slag discharging amount of the converter is reduced, and aluminum reduction (SiO) in the LF refining process is avoided 2 ) Causing Si content to exceed the standard.
2. The converter tapping adopts carbon particle pre-deoxidation, LF adopts carbon powder deoxidation, and the product is CO 2 The gas does not pollute molten steel, and is favorable for foaming steel slag and reacting the steel slag.
3. One-time aluminum addition during converter tapping realizes Al 2 O 3 The floating is generated in advance, the impurity floating removal time is increased, the reasonable stirring intensity is controlled by LF, and the secondary oxidation of Al caused by large stirring is avoided.
4. The low silicon steel produced by the method has the advantages that the silicon is not increased in the LF smelting process, the calcium treatment is eliminated, the water gap is not blocked in the continuous casting process, the quality of steel is improved, and the smelting cost is reduced.
Detailed Description
The present invention will be described in detail with reference to the following embodiments for a full understanding of the objects, features, and effects of the present invention. The process of the present invention is carried out by methods or apparatus conventional in the art, except as described below. The following terms have the meanings commonly understood by those skilled in the art unless otherwise indicated.
Unless otherwise indicated, "%" in the present invention means "% by mass".
Aiming at the conditions that aluminum reduction silicon increase is adopted in low-silicon steel, water blocking is easy to occur in the continuous casting steel casting process, the low-silicon steel smelting method is developed, silicon increase in the smelting process can be avoided, the silicon content exceeds the standard, and continuous casting is smoothly realized.
At present, in the low silicon steel production process, aluminum reduction can cause the silicon content of molten steel to exceed the standard, and the water gap is easy to be blocked in the continuous casting steel pouring process, aiming at the problems, the inventor of the invention carries out intensive study on the smelting process and the technological parameters, thereby providing a low silicon steel smelting method, the technological route of which is as follows: molten iron pretreatment, converter, LF refining and continuous casting.
The basic conception of the low silicon steel smelting method of the invention is that:
1. reduction of SiO in slag 2 Content, preventing aluminum from reducing SiO in refining process 2 Causing Si content exceeding the standard;
2. deoxidizing by adopting carbon in smelting, and reducing Al 2 O 3 The inclusion amount; the converter tapping adopts carbon particle pre-deoxidation, so that the consumption of deoxidizer aluminum is reduced, the LF adopts carbon powder diffusion deoxidation, and Al in the refining process is reduced 2 O 3 The generation amount avoids the blockage of a rear water gap;
3. the converter adopts a one-time aluminum adding method to generate Al in advance 2 O 3 The rear part is not added with aluminum any more, thus avoiding new Al 2 O 3 Inclusions are generated, and Al is prolonged 2 O 3 And removing the inclusion floating time.
Based on the design concept, the low-silicon steel smelting method specifically comprises the following steps:
(1) Smelting in a converter.
Molten iron is pretreated and then is put into a converter for smelting. The pretreatment method of the molten iron can adopt related schemes in the prior art, and details are not repeated here.
In the invention, the converter smelting process adopts double slag operation, after the earlier desilication of the converter is finished, a part of desilication slag is poured, the pouring amount is 40-60%, new slag is regenerated for decarburization, and the alkalinity of the converter slag is controlled to be 3.5-4.5.
In the present inventionIn the clear, the earlier desilication of the converter is finished, namely Si+O 2 ＝SiO 2 After the reaction, the end of the desilication of the converter can be determined by the amount of oxygen blown by the amount of oxygen=the amount of molten iron, the silicon content of molten iron, 28 x 32 x and the oxygen utilization.
In the invention, 40 to 60 percent of slag is poured after the desilication of the converter is finished, thereby not only reducing SiO 2 The amount of lime can be reduced, the slag alkalinity can be improved, and dephosphorization efficiency can be improved and furnace lining can be protected.
Based on the study of the inventor, the desilication of the converter is finished to enter into a decarburization period, and SiO is generated due to the desilication 2 More slag basicity (CaO/SiO) 2 ) The lower cost is about 1.2, lime is added in the decarburization period to re-slag in order to ensure dephosphorization of the converter and protect the furnace lining, and the alkalinity of slag is improved to about 3.0. The concrete operation of decarburizing the reconstructed new slag belongs to the conventional operation. The invention adopts a double slag method of pouring out desilication slag and then re-slagging, which can rapidly improve the alkalinity of slag to 3.5-4.5 and can improve the dephosphorization rate of the converter.
The invention is realized by reducing the total SiO in slag 2 The content of the slag is increased to 3.5 to 4.5 by adding a small amount of lime.
In the invention, the converter smelting is controlled to end oxidizing property, a high-flow bottom blowing process is adopted, and [ C ] is controlled before tapping]﹒[O]Less than or equal to 0.0016, and blowing CO before tapping 2 Stirring for 1.5-2.5 min, and the strength of bottom blowing air is 0.15-0.20 Nm 3 /(min. T) (i.e., 0.15 to 0.20Nm per ton of molten steel per minute) 3 ) Preferably 0.20Nm 3 And (5) adopting a slag blocking cone and a sliding plate to block slag during converter tapping, wherein the slag thickness of the slag is less than 30mm.
Wherein [ C ] [ O ] is called carbon oxygen product, which is the product of C content and O content in molten steel, carbon oxygen product is generally used for expressing oxidizing property in steel in steelmaking, carbon oxygen product is high for expressing oxidizing property, deoxidizer dosage is large, produced inclusion content is large, smelting is unfavorable, converter normal condition [ C ] [ O ] is 0.0018-0.0023, lower carbon oxygen product (less than or equal to 0.0016) is controlled, and deoxidizer aluminum addition amount can be reduced.
Bottom blowing inert gas (N) 2 、Ar、CO 2 ) Can be put into practiceStirring in the existing converter, accelerating the flow of molten steel in the converter, promoting the rapid progress and uniform temperature of decarburization reaction in the converter, reducing the oxygen content in the steel and reducing the [ C ] of the molten steel]﹒[O]The bottom blowing gas adopts CO 2 。
In short, the step is to manufacture high-alkalinity furnace slag by double slag operation of a converter, and reduce SiO in the converter slag 2 The content of the aluminum alloy is reduced, the converter tapping adopts double slag blocking operation, the slag discharging amount of the converter is reduced, and the aluminum reduction of SiO in the LF refining process is avoided 2 Causing Si content to exceed the standard.
(2) Tapping by a converter.
In the invention, the converter tapping adopts carbon particle pre-deoxidation, and carbon powder is added into the ladle according to the amount of 0.2-0.3 kg/t (namely, 0.2-0.3 kg of carbon powder per ton of molten steel). And (3) during tapping 2/3, adding manganese alloy and aluminum pellets for deep deoxidization, adding all aluminum during tapping of the converter, adding lime 5-6 kg/t (namely lime 5-6 kg per ton of molten steel), rapidly forming slag by utilizing impact of tapping steel flow, and stirring for 2-3 min by high-flow bottom blowing after tapping is finished.
In the present invention, the addition amount of the manganese alloy is determined according to the Mn content of the steel grade, the addition amount of the manganese alloy=the Mn content of the molten steel amount x%; the addition amount of the aluminum pellets is generally controlled within 500 kg/furnace, i.e., within 2.8kg/t steel.
The blowing air supply intensity of the converter bottom is more than or equal to 0.10Nm 3 The gas/(min, t) can be called high-flow bottom blowing, and the bottom blowing gas can be Ar and CO 2 The invention adopts bottom blowing CO 2 . Based on the research of the inventor, the high-flow bottom blowing of the converter can reduce the carbon-oxygen accumulation in steel and reduce the oxidizing property of molten steel.
In short, the converter tapping adopts carbon particle pre-deoxidation, and the product is CO 2 The gas does not pollute molten steel, is favorable for foaming steel slag and reacting slag steel, and can reduce the addition amount of aluminum, thereby reducing Al 2 O 3 Is produced in the same amount as the production amount. In addition, aluminum is added at one time after tapping in a converter, thereby realizing Al 2 O 3 The floating is generated in advance, and the time for removing the impurity floating is increased. By reducing Al 2 O 3 And (3) the amount of Al produced and 2 O 3 the floating is generated in advance, so that the blocking probability of the water gap can be reduced.
(3) LF refining.
In the invention, after molten steel enters an LF furnace, the slag surface is subjected to diffusion deoxidation by adopting carbon powder, the carbon powder amount is 15-30 kg/furnace, the LF is used for manufacturing high-alkalinity refining slag, and the components of the high-alkalinity refining slag are as follows: (FeO+MnO) is less than or equal to 1.0%, caO is 50% -60%, siO 2 8％～12％，Al 2 O 3 20-30% of MgO and 6-8%. The silicon increment in the smelting process can be reduced by manufacturing high-alkalinity refining slag.
Slag is required to be removed when tapping is carried out by a converter, the alkalinity of the converter slag is 3.5, and silicon contained in the alloy is oxidized to generate SiO 2 The alkalinity of LF initial slag is less than or equal to 3.5, converter tapping or LF entering station is needed to add lime for slag making, and the slag alkalinity (CaO/SiO) is improved 2 ) Reaching 5 to 10, namely LF to produce high alkalinity refining slag.
The lower the content of (FeO+MnO) in the slag is, the weaker the slag is, and the better the deoxidizing and desulfurizing effect of the slag is. The LF slag surface adopts carbon powder, can react with (FeO+MnO) in slag, feO+C=Fe+CO ∈, mnO+C=Mn+CO +..
In the invention, the LF refining process blows CO at bottom 2 The gas stirring adopts middle stirring, the bottom blowing strength is 200-400L/min, and large stirring is not performed in the process, so that secondary oxidation of aluminum caused by naked molten steel is prevented. Soft stirring is carried out before tapping, the soft stirring time of molten steel is more than 10min, and tapping is carried out after the temperature components are proper.
Wherein, soft stirring means that the molten steel surface slightly fluctuates, but the molten steel surface is not exposed, the molten steel is subjected to soft stirring, so that the floating removal of inclusions in the steel can be promoted, the purity of the molten steel is improved, the longer the soft stirring time is, the higher the inclusion removal rate is, and the more pure the steel quality is; if the stirring intensity is high, the molten steel surface is exposed, O in the air 2 Will react with Al in the steel to generate Al 2 O 3 The impurities pollute the molten steel and reduce the purity of the molten steel.
In short, similar to the effect of carbon pre-deoxidation for converter tapping, the LF refining adopts carbon powder for deoxidation, and the product isCO 2 The gas does not pollute molten steel, and is favorable for foaming steel slag and reacting the steel slag. In addition, the stirring intensity is controlled in the LF refining process, large stirring is not carried out, and secondary oxidation of aluminum can be avoided.
The molten steel output by the LF furnace is hung to a continuous casting process for continuous casting, and specific reference can be made to related schemes in the prior art, and details are not repeated here.
The smelting method of the low silicon steel can be suitable for the production of any type of low silicon steel, such as low silicon steel Q195LD, SPHC, S275JR-1, S355JR-1 and other steel types with Si less than or equal to 0.03 percent.
The low silicon steel smelting method can control the Si content in the LF refined molten steel to be less than or equal to 0.02 percent of Si, for example, the Si content is 0.005 to 0.020 percent.
Examples
The invention is further illustrated by means of the following examples, which are not intended to limit the scope of the invention. The experimental methods without specific conditions noted in the following examples follow conventional methods and conditions.
Example 1: q195LD low silicon steel produced by 180 ton converter
In the embodiment, 180 tons of converters are adopted to smelt the Q195LD low silicon steel (the main components of the Q195LD steel are that C is less than or equal to 0.06 percent, si is less than or equal to 0.03 percent, mn is 0.25 to 0.50 percent, P is less than or equal to 0.025 percent, S is less than or equal to 0.020 percent and Al is 0.02 to 0.07 percent). The process route is as follows: molten iron pretreatment, converter, LF refining and continuous casting.
The procedure of this example is as follows:
(1) The converter smelting process adopts double slag operation, after the earlier desilication of the converter is finished, a part of desilication slag is poured, the pouring slag amount is 50%, new slag is regenerated for decarburization, the alkalinity of the converter slag is controlled to be 4.2, the terminal oxidizing property is controlled in the converter smelting process, a large-flow bottom blowing process is adopted, and the [ C ] is controlled before tapping]﹒[O]Less than or equal to 0.0016, and blowing CO before tapping 2 Stirring for 2.0min, and bottom blowing air supply intensity of 0.20Nm 3 And (5) adopting a slag blocking cone and a sliding plate to block slag during converter tapping, wherein the slag thickness of the slag is less than 30mm.
(2) Carbon particle pre-deoxidization is adopted for converter tapping, 40kg of carbon powder is added into a steel ladle, 820kg of medium manganese alloy is added when tapping is carried out for 2/3, 500kg of aluminum pellets are added when tapping is carried out, 1000kg of lime is added, the steel flow impact is utilized for rapid slag formation, and after tapping is finished, large-flow bottom blowing stirring is carried out for 3min.
(3) After molten steel enters LF, the slag surface is subjected to diffusion deoxidation by adopting carbon powder, the carbon powder amount is 30 kg/furnace, LF is used for manufacturing high-alkalinity refined slag, and slag components CaO:53, siO 2 ：9％，Al 2 O 3 :28%, mgO:7.5%. In the LF refining process, bottom blowing stirring is adopted, the bottom blowing strength is 300L/min, large stirring is not carried out in the process, and secondary oxidation of aluminum caused by naked molten steel is prevented. Soft stirring is carried out before tapping, the soft stirring time of molten steel is 12min, and tapping is carried out after the temperature components are proper. Tapping: c:0.034%, si:0.015%, mn:0.35%, P:0.015%, S:0.010%, al:0.045%.
And (5) hanging the molten steel to a continuous casting process for continuous casting.
Example 2: s355JR-1 low silicon steel produced by 180 ton converter
In the embodiment, 180 tons of converters are adopted to smelt S355JR-1 low silicon steel (the main components of the S355JR-1 steel are that C is less than or equal to 0.06 percent, si is less than or equal to 0.03 percent, mn is 1.20 to 1.40 percent, P is less than or equal to 0.020 percent, S is less than or equal to 0.015 percent, al is 0.015 to 0.06 percent, cr is 0.3 to 0.35 percent, and Nb is 0.017 to 0.027 percent). The process route is as follows: molten iron pretreatment, converter, LF refining and continuous casting.
The procedure of this example is as follows:
(1) The converter smelting process adopts double slag operation, after the earlier desilication of the converter is finished, a part of desilication slag is poured, the pouring slag amount is 50%, new slag is regenerated for decarburization, the alkalinity of the converter slag is controlled to be 4.2, the terminal oxidizing property is controlled in the converter smelting process, a large-flow bottom blowing process is adopted, and the [ C ] is controlled before tapping]﹒[O]Less than or equal to 0.0016, and blowing CO before tapping 2 Stirring for 2.0min, and bottom blowing air supply intensity of 0.20Nm 3 And (5) adopting a slag blocking cone and a sliding plate to block slag during converter tapping, wherein the slag thickness of the slag is less than 30mm.
(2) The converter tapping adopts carbon particle pre-deoxidation, 50kg of carbon powder is added into a ladle, 2900kg of medium manganese alloy is added when tapping is carried out for 2/3, 500kg of aluminum pellets are added when tapping the converter, 1000kg of lime is added, the tapping steel flow is utilized to impact and rapidly form slag, and after tapping is finished, large-flow bottom blowing stirring is carried out for 3min.
(3) After molten steel enters LF, the slag surface is subjected to diffusion deoxidation by adopting carbon powder, the carbon powder amount is 30 kg/furnace, LF is used for manufacturing high-alkalinity refined slag, and slag components CaO:55%, siO 2 ：10％，Al 2 O 3 :26%, mgO:7%. In the LF refining process, bottom blowing stirring is adopted, the bottom blowing strength is 320L/min, and large stirring is not carried out in the process, so that secondary oxidation of aluminum caused by naked molten steel is prevented. Soft stirring is carried out before tapping, the soft stirring time of molten steel is 12min, and tapping is carried out after the temperature components are proper. Tapping: c:0.03%, si:0.018%, mn:1.25%, P:0.015%, S:0.010%, al:0.040%.
And (5) hanging the molten steel to a continuous casting process for continuous casting.
Comparative example 1: q195LD low silicon steel produced by 180 ton converter
The comparative example adopts 180 tons of converters to smelt Q195LD low silicon steel (the main components of Q195LD steel are that C is less than or equal to 0.06 percent, si is less than or equal to 0.03 percent, mn is 0.25 to 0.50 percent, P is less than or equal to 0.025 percent, S is less than or equal to 0.020 percent, and Al is 0.02 to 0.07 percent). The process route is as follows: molten iron pretreatment, converter, LF refining and continuous casting.
The procedure of the comparative example is as follows:
(1) The converter smelting adopts a single slag method to operate, the alkalinity of the converter slag is controlled to be 3.2, the converter adopts a large-flow bottom blowing process, the [ C ] and the [ O ] before tapping are 0.0020, the converter tapping adopts a sliding plate to stop slag, and the slag-discharging thickness is less than 50mm.
(2) Aluminum deoxidization is adopted for converter tapping, 820kg of medium manganese alloy is added, 450kg of aluminum balls are added during converter tapping, 1000kg of lime is added, rapid slag formation is achieved by utilizing steel flow impact of tapping, and large-flow bottom blowing stirring is carried out for 3min after tapping is finished.
(3) After molten steel enters LF, 500kg of lime is added, slag is stirred at a large flow, 150kg of aluminum balls are added in the LF smelting process, and the slag component CaO of LF refining slag is as follows: 50%, siO 2 ：4.5％，Al 2 O 3 :34%, mgO:8%. Soft stirring is carried out before tapping, the soft stirring time of molten steel is 12min, and tapping is carried out after the temperature components are proper. Tapping: c:0.034%, si:0.038%, mn:0.35%, P:0.015%, S:0.010%, al: 0.045%)
And (5) hanging the molten steel to a continuous casting process for continuous casting.
The comparative effects of examples and comparative examples are shown in the following table:
according to the embodiment and the comparative example, the silicon content of the finished product can be controlled to be less than or equal to 0.02 percent, the aluminum consumption is reduced under the condition that the aluminum of the finished product is equivalent, the aluminum consumption can be saved by 0.55kg/t, the lime consumption is reduced by 2.77kg/t, the cost is reduced, and the quality of steel is improved.
The foregoing examples are illustrative of the present invention and are not intended to be limiting, and any other substitutions, modifications, combinations, alterations, simplifications, etc. which do not depart from the spirit and principles of the present invention are intended to be within the scope of the present invention.
Claims (10)
1. The low silicon steel smelting method is characterized by comprising the following steps of:
(1) Charging the pretreated molten iron into a converter, adopting double slag operation in the smelting process, pouring out a part of desilication slag after desilication is finished, reconstructing new slag for decarburization, and controlling the alkalinity of the converter slag;
(2) Tapping in a converter, adding carbon powder into a ladle for pre-deoxidization, and adding manganese alloy and aluminum pellets into the ladle for deep deoxidization when tapping reaches a certain degree;
(3) Molten steel enters an LF furnace, carbon powder is adopted for diffusion deoxidation on the slag surface, and high-alkalinity refining slag is produced in the refining process.
2. The method of smelting low silicon steel according to claim 1, wherein the amount of slag removed after the desilication is 40 to 60% in the step (1).
3. The low silicon steel smelting process according to claim 1, wherein in the step (1), the basicity of the converter slag is controlled to be 3.5 to 4.5.
4. The method of smelting low silicon steel according to claim 1, wherein in the step (1), before the end of the converter smelting and tapping, C is controlled]﹒[O]Less than or equal to 0.0016, according to 0.15 to 0.20Nm 3 Air supply intensity bottom blowing CO of/(min × t) 2 Stirring for 1.5-2.5 min.
5. The method for smelting low silicon steel according to claim 1, wherein in the step (2), the converter tapping adopts a double slag-stopping operation of a slag-stopping cone and a sliding plate slag-stopping, and the slag-discharging thickness is less than 30mm.
6. The method of smelting low silicon steel according to claim 1, wherein in the step (2), carbon powder is added to the ladle in an amount of 0.2 to 0.3 kg/t; and (3) adding manganese alloy and aluminum pellets for deep deoxidization when tapping 2/3, and ensuring that the aluminum pellets are completely added when tapping in the converter.
7. The method of smelting low silicon steel according to claim 1, wherein in the step (2), lime is added at 5 to 6kg/t during tapping in the converter, and slag is formed by impact of the tapped steel flow; after tapping of the converter, stirring for 2-3 min by high-flow bottom blowing.
8. The method of smelting low silicon steel according to claim 1, wherein in the step (3), the amount of carbon powder is 15 to 30 kg/furnace, and the high alkalinity refining slag comprises the following components: caO 50-60%, siO 2 8％～12％，Al 2 O 3 20％～30％，MgO 6％～8％。
9. The method of smelting low silicon steel according to claim 1, wherein in the step (3), the bottom blowing strength of 200 to 400L/min is used for bottom blowing stirring in the refining process.
10. The method of smelting low silicon steel according to claim 1, wherein in the step (3), soft stirring is performed before tapping, the bottom blowing strength is 50-100L/min, and the soft stirring time of molten steel is more than 10min.
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