CN115612775A - Smelting method of molten iron - Google Patents
Smelting method of molten iron Download PDFInfo
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- CN115612775A CN115612775A CN202211214891.1A CN202211214891A CN115612775A CN 115612775 A CN115612775 A CN 115612775A CN 202211214891 A CN202211214891 A CN 202211214891A CN 115612775 A CN115612775 A CN 115612775A
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- molten iron
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- iron
- spraying
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 355
- 229910052742 iron Inorganic materials 0.000 title claims abstract description 176
- 238000000034 method Methods 0.000 title claims abstract description 82
- 238000003723 Smelting Methods 0.000 title claims abstract description 21
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims abstract description 84
- 229910052749 magnesium Inorganic materials 0.000 claims abstract description 84
- 239000011777 magnesium Substances 0.000 claims abstract description 84
- 239000002893 slag Substances 0.000 claims abstract description 74
- 238000005507 spraying Methods 0.000 claims abstract description 55
- 230000008569 process Effects 0.000 claims abstract description 50
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 43
- 239000000203 mixture Substances 0.000 claims abstract description 32
- 239000011593 sulfur Substances 0.000 claims abstract description 27
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims abstract description 26
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 36
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 36
- 239000004571 lime Substances 0.000 claims description 36
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 25
- 239000010436 fluorite Substances 0.000 claims description 25
- 239000003795 chemical substances by application Substances 0.000 claims description 15
- 238000002347 injection Methods 0.000 claims description 3
- 239000007924 injection Substances 0.000 claims description 3
- 238000006477 desulfuration reaction Methods 0.000 abstract description 55
- 230000023556 desulfurization Effects 0.000 abstract description 55
- 238000004519 manufacturing process Methods 0.000 abstract description 6
- 230000033764 rhythmic process Effects 0.000 abstract description 3
- 229910052698 phosphorus Inorganic materials 0.000 description 16
- 238000007664 blowing Methods 0.000 description 10
- 239000002245 particle Substances 0.000 description 9
- 239000007921 spray Substances 0.000 description 9
- 229910052751 metal Inorganic materials 0.000 description 8
- 239000002184 metal Substances 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- 239000000047 product Substances 0.000 description 7
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 6
- 229910000831 Steel Inorganic materials 0.000 description 6
- 238000010079 rubber tapping Methods 0.000 description 6
- 238000005070 sampling Methods 0.000 description 6
- 239000010959 steel Substances 0.000 description 6
- 239000007788 liquid Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- 238000009529 body temperature measurement Methods 0.000 description 4
- 150000001669 calcium Chemical class 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 239000000428 dust Substances 0.000 description 4
- 239000004615 ingredient Substances 0.000 description 4
- 235000019738 Limestone Nutrition 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 235000012255 calcium oxide Nutrition 0.000 description 3
- 239000000292 calcium oxide Substances 0.000 description 3
- 239000002131 composite material Substances 0.000 description 3
- 238000004090 dissolution Methods 0.000 description 3
- 239000006028 limestone Substances 0.000 description 3
- 238000007790 scraping Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000003009 desulfurizing effect Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- XWHPIFXRKKHEKR-UHFFFAOYSA-N iron silicon Chemical compound [Si].[Fe] XWHPIFXRKKHEKR-UHFFFAOYSA-N 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- GJEAMHAFPYZYDE-UHFFFAOYSA-N [C].[S] Chemical compound [C].[S] GJEAMHAFPYZYDE-UHFFFAOYSA-N 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000009851 ferrous metallurgy Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000003892 spreading Methods 0.000 description 1
- 230000007480 spreading Effects 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000000859 sublimation Methods 0.000 description 1
- 230000008022 sublimation Effects 0.000 description 1
- 150000003464 sulfur compounds Chemical class 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Images
Classifications
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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
Abstract
The invention provides a smelting method of molten iron, which comprises the following steps: and (4) turning iron, spraying magnesium and slagging off in sequence. The method provided by the invention can realize that the sulfur content of the pretreated molten iron is stabilized below 0.002% under the process of singly spraying the granular magnesium, and does not occupy the production rhythm of the normal molten iron pretreatment; the desulfurization product is easy to remove by changing the composition of the slag phase, the residue of the desulfurization product after slagging-off treatment is small, and the content of sulfur element in the desulfurization slag is lower than the conventional content, so that the smelting resulfurization phenomenon is solved.
Description
Technical Field
The invention belongs to the technical field of molten iron, and particularly relates to a molten iron smelting method.
Background
The main process flow of the molten iron smelting comprises the following steps: the method comprises the following steps of sitting a ladle on a hot metal car at a ladle pouring station, driving the hot metal car to a ladle overturning position, starting to overturn iron, finishing overturning iron, driving the hot metal car to a ladle hanging position, lifting the ladle to a hot metal pretreatment station by a crown block, placing the ladle on a hot metal tipper, driving the tipper to a blowing position, starting to supply magnesium to a lower spray gun for blowing, finishing blowing, tipping the ladle, starting to scrape slag, adding a slag conglomeration agent, continuously scraping slag → measuring temperature, sampling, driving the tipper to the ladle hanging position, lifting the ladle to a converter platform by the crown block, feeding the ladle to a converter/electric furnace for iron adding, starting to converter/electric furnace smelting, finishing smelting, measuring temperature and sampling.
The KR method, the composite blowing method and the single-spraying particle magnesium method are three main processes of molten iron pretreatment and desulfurization in the ferrous metallurgy industry, and the single-spraying particle magnesium has the excellent characteristics of highest magnesium utilization rate, low unit consumption of a desulfurizing agent, minimum iron loss during treatment, minimum temperature drop of molten iron, short molten iron treatment time and high adaptability of molten iron. After entering molten iron, a small part of solid metal magnesium particles are dissolved in the molten iron and quickly reach saturated dissolution; most of the magnesium particles form magnesium vapor bubbles in the molten iron after sublimation. Because the desulfurizer only has pure passivated magnesium and cannot meet the requirement of stable deep desulfurization, a formed desulfurization product MgS is not easy to remove and mainly exists in a liquid slag form, the sulfur element content of a main desulfurization product (desulfurization slag) can reach over 3 percent, if the removal is not clean, the resulfurization phenomenon is easy to occur in the smelting process when an ultra-low sulfur product is produced, so that the sulfur element content of a final product cannot reach the delivery standard, and the industry generally believes that the adaptability of a single-spray granular magnesium molten iron pretreatment desulfurization process to the production of ultra-low sulfur steel is poor.
In order to realize the deep desulfurization of molten iron and solve the problem of resulfurization, thereby realizing the production of low-sulfur products, two processes, namely a KR (lime stirring process) process and a composite blowing (particle magnesium and fluidized lime powder) process are generally selected in the industry, both the two processes can realize a stable deep desulfurization effect (S is less than or equal to 0.002%), but both the two processes have the problems of large temperature drop, high energy consumption, complex composition of a desulfurizing agent and long treatment period, and are more suitable for the production conditions of slow production rhythm and stable molten iron temperature and quality.
For single-shot particle magnesium desulfurization, although metal magnesium has strong affinity with sulfur, and the magnesium and the sulfur in molten iron can achieve the purpose of removing the sulfur in the molten iron through chemical reaction, the consumption of the magnesium is greatly increased aiming at deep desulfurization treatment, and the cost is increased. Firstly, after the passivated particle magnesium is sprayed into molten iron, the passivated particle magnesium floats to the surface of the molten iron, and loses desulfurization effect after floating to the surface of the molten iron; in the latter stage of blowing, the molten iron temperature and the sulfur content in the molten iron are reduced, so that the dissolution loss is increased, the utilization rate of magnesium in the later stage is reduced rapidly after the dissolution loss is increased, and the sulfur content in the molten iron is difficult to reduce to below 0.002%.
In order to improve the deep desulfurization effect of single-spray granular magnesium, calcium raw materials such as quicklime, limestone and the like are generally added into a ladle before the start of a molten iron pretreatment desulfurization process in the industry, and a part of desulfurization effect is realized by means of the dynamic condition of turning iron by the ladle, but the actual main desulfurization link still depends on the reaction of passivated magnesium and molten iron, so that the problem of unstable deep desulfurization cannot be effectively solved. Because the feeding link before turning over iron is added, the whole pretreatment period of the molten iron is prolonged, and the advantage of short whole treatment period of a part of single-spraying particle magnesium desulfurization process is counteracted. In addition, the passivated lime is added at one time in the treatment process, the procurement cost of the passivated lime is high, the regional resource supply is limited, and the lime is easy to agglomerate after the passivated lime is added at one time, caO in the lime cannot fully react with sulfur in the molten iron, so that an effective deep desulfurization effect cannot be realized in the practical application process.
Disclosure of Invention
In view of this, the invention aims to provide a method for smelting molten iron, which can stably realize deep desulfurization and avoid resulfurization in the smelting process of a converter electric furnace.
The invention provides a smelting method of molten iron, which comprises the following steps:
turning iron, spraying magnesium and removing slag in sequence.
Preferably, the molten iron comprises the following components:
C：4.0％～4.7wt％，
Si：0.30％～0.60wt％，
Mn：0.30％～0.40wt％，
P≤0.120wt％，
S≤0.035wt％，
the balance being Fe.
Preferably, the tilting angle in the iron turning process is 0 to +/-150 degrees.
Preferably, the mixture of lime and fluorite is continuously added into the molten iron when the magnesium is sprayed to the total magnesium spraying amount of 60-70% in the magnesium spraying process.
Preferably, the mass ratio of the lime to the fluorite is (6-8): (1-1.5).
Preferably, the amount of the mixture of lime and fluorite added to one ton of molten iron is 7 to 8kg.
Preferably, the material speed in the process of adding the mixture of lime and fluorite is 300-350 kg/min.
Preferably, the temperature of the molten iron before magnesium spraying is more than 1300 ℃;
the mass content of Si in the molten iron is 0.3-0.6%, the mass content of P is less than or equal to 0.120%, and the mass content of S is less than or equal to 0.035%.
Preferably, the sulfur content in the molten iron after magnesium spraying is below 0.0020 wt%.
Preferably, the slag conglomeration agent is added when 1/2-2/3 of the total slag amount of the molten iron is removed in the slag removing process.
In the later stage of the desulfurization of the single-spraying granular magnesium, the utilization rate of the magnesium is sharply reduced, so that the sulfur content in the molten iron is difficult to reduce to below 0.002 percent. In order to solve the problem of difficult later-stage desulfurization, a large amount of practices show that when the magnesium spraying reaches 60-70% of the total weight, a lime fluorite mixed substance (active lime and fluorite are uniformly mixed according to 8. Aiming at enterprises only adopting the single-spraying granular magnesium process, a deep desulfurization way is provided.
The research of the invention finds that the desulfurization and resulfurization of the single-spray granular magnesium mainly relates to whether the desulfurization products can be removed to the maximum extent in the slag skimming process, because the molten iron subjected to desulfurization of the single-spray granular magnesium processed conventionally has small and thin slag amount, and is difficult to be skived off by using the conventional slag skimming means, so that the desulfurized slag with high enrichment of MgS is mixed into the converter along with the molten iron, the desulfurization load of the converter is increased in the smelting process of the converter, the resulfurization phenomenon is caused under the oxidizing atmosphere of the converter or an electric furnace, and finally the desulfurization effect of the molten steel is unstable, so that the molten steel has defects in adapting to steel types.
Because the molten iron slag amount after the desulfurization of the single-spray granular magnesium is small and thin, in order to ensure that the resulfurization does not occur or the resulfurization is reduced in the smelting process of a converter/electric furnace, a large amount of slag conglomeration agent is added in the slag skimming stage after the spraying, the waste of the slag conglomeration agent is caused, so that the cost is increased, and a layer of liquid slag is formed on the surface of the skived slag due to the thin slag conglomeration, so that the sulfur content of the liquid slag is extremely high, the sulfur element returns to the molten iron again, and the resulfurization can not be inhibited.
The method provided by the invention can stabilize the sulfur content of the pretreated molten iron to be below 0.002% under the process of single-spraying granular magnesium on the pretreated molten iron, and does not occupy the production rhythm of the pretreatment of the molten iron; the desulfurization product is easy to remove by changing the composition of the slag phase, the residue of the desulfurization product after slagging-off treatment is small, and the content of sulfur element in the desulfurization slag is lower than the conventional content, so that the smelting resulfurization phenomenon is solved.
In the invention, the pretreatment of the molten iron by using the single-spray granular magnesium refers to a treatment process for reducing the content of sulfur elements in the molten iron by utilizing passivated magnesium and directly blowing the passivated magnesium into the molten iron through nitrogen conveying. The deep desulfurization refers to that the content of sulfur element in the molten iron is reduced to be less than 0.002 percent through a molten iron pretreatment process. The resulfurization means that the pretreated desulfurized molten iron enters a converter and an electric furnace for smelting, and sulfur elements in the molten iron slag are returned to the molten steel again due to the oxidizing atmosphere of smelting.
Drawings
FIG. 1 is a process flow chart for preparing molten steel according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
The invention provides a smelting method of molten iron, which comprises the following steps:
and (4) turning iron, spraying magnesium and slagging off in sequence.
In the present invention, the molten iron preferably includes:
C：4.0％～4.7wt％，
Si：0.30％～0.60wt％，
Mn：0.30％～0.40wt％，
P≤0.120wt％，
S≤0.035wt％，
the balance being Fe.
In the present invention, the mass content of C is preferably 4.1 to 4.6%, more preferably 4.2 to 4.5%, most preferably 4.3 to 4.4%; the mass content of Si is preferably 0.4 to 0.5%, more preferably 0.45%; the mass content of Mn is preferably 0.35%.
In the invention, the iron turning is preferably carried out in a tank pouring station; in the process of turning the iron, the torpedo car is turned to a tipping position, the hot metal car is turned to a tapping position, the torpedo car is turned after being electrified, and the tipping angle is preferably 0-150 degrees. In the invention, when the weight of the molten iron is 20-25 t away from the specified weight, the tilting angle is preferably reduced to realize small tapping, so that the molten iron is prevented from overflowing the iron ladle; calcium series raw materials such as quick lime, limestone and the like are preferably not added in the process of turning the iron, so that the cost is reduced while the iron turning time is saved, the dust raising phenomenon is easily caused by adding the calcium series raw materials during iron turning, the environment is polluted, and the dust raising phenomenon of the iron turning is avoided by using the method. In the invention, after the iron tapping is preferably finished in the iron turning process, the molten iron car is driven to a temperature measurement sampling position for temperature measurement sampling, and then is lifted to a desulfurization station by a crown block.
In the invention, before the magnesium spraying, the ladle is preferably lifted to the molten iron tipping vehicle and driven to the spraying position. In the present invention, the conditions before the magnesium injection, i.e., when the molten iron enters the desulfurization station, are preferably C: 4.0-4.7 wt%, si: 0.30-0.60 wt%, mn: 0.30-0.40 wt%, P is less than or equal to 0.120wt%, S is less than or equal to 0.035wt%, and the molten iron is transferred to a desulfurization station after being turned over by a ladle transfer station. In the present invention, the temperature of the molten iron entering the desulfurization station is preferably > 1300 ℃, more preferably 1300 to 1340 ℃, and most preferably 1310 to 1330 ℃; the mass content of Si in the molten iron is preferably 0.3 to 0.6%, more preferably 0.4 to 0.5%; the mass content of P in the molten iron is preferably less than or equal to 0.120 percent, and the mass content of S in the molten iron is preferably less than or equal to 0.030 percent. In the invention, preferably, the molten iron enters the desulfurization station without slagging off, the original slag is reserved, and compared with the operation of slagging off and blowing in the desulfurization station, the method provided by the invention does not carry out slagging off operation after the steel car is driven to the desulfurization station, the original molten iron slag is reserved, the slag amount is increased, the percentage content of sulfur compounds in the slag is favorably reduced, the forward proceeding of the desulfurization reaction is favorably realized, and favorable conditions are provided for realizing the deep desulfurization of the molten iron.
In the present invention, it is preferable that the mixture of lime and fluorite is continuously added to the ladle when the amount of sprayed magnesium reaches 60 to 70% of the total sprayed magnesium amount in the magnesium spraying process, more preferably 63 to 67%, and most preferably 65%. In the invention, when the total weight of the sprayed magnesium is 60-70%, the uniformly mixed lime and fluorite is preferably continuously added into the foundry ladle by a blanking device, and the adding amount of molten iron per ton is preferably 7-8 kg, more preferably 7.5kg; the material speed is controlled to be preferably 300 to 350kg/min, more preferably 310 to 340kg/min, and most preferably 320 to 330kg/min; the mass ratio of lime to fluorite is preferably (6-8): (1 to 1.5), more preferably (6.5 to 7.5): (1.1 to 1.4), most preferably 7: (1.2-1.3); the lime is preferably activated lime.
In the invention, in the magnesium spraying process, the lime and fluorite mixture is preferably continuously and uniformly added into the molten iron through a feeding hopper, so that the composite spraying effect is achieved, the desulfurization reaction is more thorough by utilizing the dynamic condition of spraying, and finally the sulfur content of the molten iron is stably below 0.0020 percent.
In the magnesium spraying process, preferably, the molten iron car is firstly driven to a spraying position, the magnesium spraying amount is determined according to different molten iron silicon and sulfur components, and the spray gun is used for spraying passivated magnesium. In the invention, the strength of magnesium supplied in the magnesium spraying process is preferably controlled to be 5-8 kg per minute, more preferably 6-7 kg, and most preferably 6.5kg; the magnesium spraying time is preferably 6-16 min, more preferably 8-14 min, and most preferably 10-12 min; the amount of sprayed magnesium is preferably 30 to 80kg, more preferably 40 to 70kg, and most preferably 50 to 60kg.
In the invention, when the total magnesium spraying amount is preferably 60-70% in the magnesium spraying process, the mixture of lime and fluorite is continuously added into the foundry ladle, the mixture of lime and fluorite is uniformly added into the foundry ladle by a vibrating feeder, and the adding amount of molten iron per ton is preferably 7-8 kg; the material speed is preferably controlled to be 300-350 kg/min.
In the invention, the functions of the slag raking machine and the molten iron tipper are preferably confirmed firstly in the slag raking process, whether the slag raker can be normally used or not is checked, after the desulfurization is finished, a hydraulic control system of the slag raker is started, the molten iron tipper is tilted until the distance between the liquid level of the molten iron and the upper part of a ladle is about 10cm, and an operating rod of the slag raker is operated to carry out slag raking operation; preferably, in the slag removing process, the slag conglomeration agent is added when the total slag amount of the molten iron is removed by 1/2-2/3, the slag conglomeration agent is preferably added in small amount for multiple times, the slag conglomeration agent is added and then spread uniformly by using a slag removing plate to be fully combined with the molten iron slag, the slag removing is continued after about 30 seconds, and the molten iron ladle is restored to a vertical state after the slag removing is finished.
In the present invention, after the slagging-off is finished, the method preferably further comprises:
and hoisting the ladle to a converter or an electric furnace, and adding molten iron into the converter or the electric furnace.
In the embodiment of the invention, the process flow of the smelting method of the molten iron is shown in figure 1 and comprises the following steps:
turning iron in a tank transferring station;
hoisting the iron ladle to a molten iron tipping vehicle and driving the molten iron tipping vehicle to a blowing position;
carrying out magnesium spraying operation, and continuously adding a lime and fluorite mixed mixture into the ladle when the magnesium spraying amount is 60-70% of the total amount;
carrying out slag skimming operation after the blowing is finished;
hoisting the ladle to a converter/electric furnace;
adding molten iron into a converter/electric furnace.
In the invention, the resource of the active lime is not limited and the price is low; the active lime can realize rapid slagging and increase the desulfurization efficiency by utilizing the advantages of high-temperature rapid melting and unique slagging of fluorite, and finally realize deep desulfurization; the composition in the slag is changed, which is more beneficial to slag skimming; the large amount of slag reduces the distribution coefficient of molten iron S in slag after removal, and effectively inhibits the return of S.
Examples
A method for smelting molten iron, comprising:
turning iron, spraying magnesium and slagging off in sequence;
in the process of turning iron, the torpedo car is turned to a tipping position, the molten iron car is turned to a tapping position, the torpedo car is turned after being electrified, the tipping angle is 0 to +/-150 degrees, when the weight of molten iron is 20-25 t away from the specified weight, the tipping angle is reduced to realize small-flow tapping, and the molten iron is prevented from overflowing an iron ladle; calcium series raw materials such as quick lime and limestone do not need to be added in the iron turning process, the iron turning time is saved, the cost is reduced, the dust raising phenomenon is easily caused by adding the calcium series raw materials during iron turning, the environment is polluted, and the iron turning dust raising phenomenon is avoided by using the method. After tapping, driving the molten iron car to a temperature measurement sampling position for temperature measurement sampling, and then hoisting the molten iron car to a desulfurization station by a crown block;
the temperature of molten iron entering a desulfurization station is higher than 1300 ℃, the mass content of Si in the molten iron is 0.3-0.6%, the mass content of P is preferably less than or equal to 0.120%, and the mass content of S is preferably less than or equal to 0.030%; the molten iron enters a desulfurization station without slagging off, and original slag is remained;
in the magnesium spraying process, firstly, the molten iron car is driven to a spraying position, the magnesium spraying amount is determined according to different molten iron silicon and sulfur components, and the spray gun is used for spraying passivated magnesium; controlling the magnesium supply strength to be 5-8 kg per minute in the magnesium spraying process, wherein the magnesium spraying time is 6-16 min, and the magnesium spraying amount is 30-80 kg; when the magnesium spraying amount reaches 60-70% of the total magnesium spraying amount, continuously adding a mixture of lime and fluorite into the ladle, continuously adding a uniformly mixed substance of the lime and the fluorite into the ladle through a blanking device, wherein the adding amount of molten iron per ton is 7-8 kg, the material speed is controlled to be 300-350 kg/min, and the mass ratio of the lime to the fluorite is (6-8): (1-1.5);
confirming functions of a slag raking machine and a molten iron tilting vehicle in the slag raking process, checking whether the slag raking machine and the molten iron tilting vehicle can be normally used or not, starting a hydraulic control system of the slag raking machine after desulfurization is finished, tilting the molten iron tilting vehicle until the distance between the liquid level of the molten iron and the upper part of a rear ladle is about 10cm, and operating an operating rod of the slag raking machine to carry out slag raking operation; and adding a slag conglomeration agent when 1/2-2/3 of the total slag amount of the molten iron is scraped, adding a small amount of the slag conglomeration agent for multiple times, uniformly spreading the slag conglomeration agent by using a slag scraping plate after adding the slag conglomeration agent so as to fully combine the slag conglomeration agent with the molten iron slag, continuing to scrape the slag after waiting for about 30s, and recovering the molten iron ladle to be in a vertical state after the slag scraping is finished.
Examples 1 to 5
The magnesium spraying process conditions are as follows: when the magnesium spraying amount is 60 percent of the total magnesium spraying amount, adding a mixture of lime and fluorite (mass ratio 6.
The molten iron comprises the following components:
example 1: the ladle inverting station turns over 150t of iron, and the molten iron composition sample C:4.2wt%, si:0.40wt%, mn:0.37wt%, P:0.105wt%, S:0.028wt%.
Example 2: iron turning 148t at the ladle inverting station, molten iron composition sample C:4.35wt%, si:0.37wt%, mn:0.35wt%, P:0.103wt%, S:0.030wt%.
Example 3: 140t of iron turning at a ladle pouring station, and the molten iron ingredient sample C:4.2wt%, si:0.33wt%, mn:0.33wt%, P:0.095wt%, S:0.025wt%.
Example 4: and (4) turning iron 147t at a ladle reversing station, and preparing a molten iron composition sample C:4.55wt%, si:0.50wt%, mn:0.37wt%, P:0.010wt%, S:0.032wt%.
Example 5: the ladle inverting station turns over iron 146t, and the molten iron composition sample C:4.3wt%, si:0.42wt%, mn:0.40wt%, P:0.100wt%, S:0.035wt%.
Examples 6 to 10
The magnesium spraying process conditions are as follows: when the magnesium spraying amount is 65 percent of the total magnesium spraying amount, adding a lime and fluorite mixture (mass ratio 7.
The molten iron comprises the following components:
example 6: 150t of iron turning in a ladle pouring station, and the molten iron ingredient sample C:4.10wt%, si:0.31wt%, mn:0.30wt%, P:0.099wt%, S:0.025wt%.
Example 7: 140t of iron turning at a ladle reversing station, and the molten iron ingredient sample C:4.6wt%, si:0.31wt%, mn:0.35wt%, P:0.111wt%, S:0.033wt%.
Example 8: the ladle inverting station turns over iron 152t, and the molten iron composition sample C:4.33wt%, si:0.51wt%, mn:0.33wt%, P:0.105wt%, S:0.027 wt.%.
Example 9: ladle overturning at a ladle dumping station 144t, molten iron composition sample C:4.05wt%, si:0.33wt%, mn:0.30wt%, P:0.100wt%, S:0.030wt%.
Example 10: iron 149t is turned over at the ladle inverting station, and the molten iron composition sample C:4.22wt%, si:0.43wt%, mn:0.31wt%, P:0.097wt%, S:0.029wt%.
Examples 11 to 15
The magnesium spraying process conditions are as follows: when the magnesium spraying amount is 65 percent of the total magnesium spraying amount, adding a lime and fluorite mixture (mass ratio is 8.
The molten iron comprises the following components:
example 11: the ladle inverting station turns over iron 152t, and the molten iron composition sample C:4.06wt%, si:0.54wt%, mn:0.32wt%, P:0.115wt%, S:0.034wt%.
Example 12: 150t of iron turning in a ladle pouring station, and the molten iron ingredient sample C:4.11wt%, si:0.60wt%, mn:0.33wt%, P:0.107wt%, S:0.022wt%.
Example 13: and (4) turning over iron 147t at a ladle reversing station, and preparing a molten iron composition sample C:4.32wt%, si:0.33wt%, mn:0.40wt%, P:0.106wt%, S:0.026wt%.
Example 14: and (4) turning iron 147t at a ladle reversing station, and preparing a molten iron composition sample C:4.50wt%, si:0.35wt%, mn:0.33wt%, P:0.101wt%, S:0.032wt%.
Example 15: turning iron 148t at a ladle reversing station, and preparing a molten iron sample C:4.17wt%, si:0.37wt%, mn:0.33wt%, P:0.104wt%, S:0.032wt%.
Performance detection
And (3) detecting the sulfur content in the molten iron discharged from the desulfurization station after magnesium spraying by using a sulfur-carbon instrument, wherein the detection result is as follows:
in the invention, the resource of the active lime is not limited and the price is low; the active lime can realize rapid slagging and increase the desulfurization efficiency by utilizing the advantages of high-temperature rapid melting and unique slagging of fluorite, and finally realize deep desulfurization; the composition in the slag is changed, which is more beneficial to slag skimming; the large amount of slag reduces the distribution coefficient of molten iron S in slag after removal, and effectively inhibits the return of S.
While the invention has been described and illustrated with reference to specific embodiments thereof, such description and illustration are not intended to limit the invention. It will be clearly understood by those skilled in the art that various changes in form and details may be made therein without departing from the true spirit and scope of the invention as defined by the appended claims, to adapt a particular situation, material, composition of matter, substance, method or process to the objective, spirit and scope of this application. All such modifications are intended to be within the scope of the claims appended hereto. Although the methods disclosed herein have been described with reference to particular operations being performed in a particular order, it should be understood that these operations may be combined, sub-divided, or reordered to form equivalent methods without departing from the teachings of the present disclosure. Accordingly, unless specifically indicated herein, the order and grouping of the operations is not a limitation of the present application.
Claims (10)
1. A method for smelting molten iron, comprising:
and (4) turning iron, spraying magnesium and slagging off in sequence.
2. The method of claim 1, wherein the composition of the molten iron comprises:
C：4.0％～4.7wt％，
Si：0.30％～0.60wt％，
Mn：0.30％～0.40wt％，
P≤0.120wt％，
S≤0.030wt％，
the balance being Fe.
3. The method of claim 1, wherein the tip angle during the tipping of the iron is 0 to ± 150 °.
4. The method of claim 1, wherein the mixture of lime and fluorite is continuously added to the molten iron when the magnesium is sprayed to a total magnesium spraying amount of 60-70% in the magnesium spraying process.
5. The method according to claim 4, characterized in that the mass ratio of lime to fluorite is (6-8): (1-1.5).
6. The method according to claim 4, wherein the mixture of lime and fluorite is added in an amount of 7-8 kg per ton of molten iron.
7. The method as claimed in claim 4, wherein the feed rate during the addition of the mixture of lime and fluorite is 300-350 kg/min.
8. The method of claim 1, wherein the temperature of the molten iron prior to the magnesium injection is > 1300 ℃;
the mass content of Si in the molten iron is 0.3-0.6%, the mass content of P is less than or equal to 0.120%, and the mass content of S is less than or equal to 0.030%.
9. The method of claim 1, wherein the sulfur content in the molten iron after magnesium injection is less than 0.0020 wt%.
10. The method according to claim 1, wherein the slag conglomeration agent is added when 1/2-2/3 of the total slag amount of the molten iron is raked out in the slag raking process.
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