CN113215476A - Method for producing industrial pure iron - Google Patents

Method for producing industrial pure iron Download PDF

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Publication number
CN113215476A
CN113215476A CN202110337726.4A CN202110337726A CN113215476A CN 113215476 A CN113215476 A CN 113215476A CN 202110337726 A CN202110337726 A CN 202110337726A CN 113215476 A CN113215476 A CN 113215476A
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equal
less
steel
slag
molten steel
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Inventor
黄治成
贾进
李小兰
黄远涛
杨建�
郭宇
彭杨
袁渊
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Hunan Valin Xiangtan Iron and Steel Co Ltd
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Hunan Valin Xiangtan Iron and Steel Co Ltd
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Priority to CN202110337726.4A priority Critical patent/CN113215476A/en
Publication of CN113215476A publication Critical patent/CN113215476A/en
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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C33/00Making ferrous alloys
    • C22C33/04Making ferrous alloys by melting
    • C22C33/06Making ferrous alloys by melting using master alloys
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21CPROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28Manufacture of steel in the converter
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21CPROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0006Adding metallic additives
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21CPROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04Removing impurities by adding a treating agent
    • C21C7/06Deoxidising, e.g. killing
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21CPROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04Removing impurities by adding a treating agent
    • C21C7/068Decarburising
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21CPROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10Handling in a vacuum
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/02Ferrous alloys, e.g. steel alloys containing silicon
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/04Ferrous alloys, e.g. steel alloys containing manganese
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/06Ferrous alloys, e.g. steel alloys containing aluminium
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/18Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/18Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium

Abstract

The method for producing the industrial pure iron comprises the following chemical compositions in percentage by weight of less than or equal to 0.01% of C, less than or equal to 0.04% of Si, less than or equal to 0.10% of Mn, less than or equal to 0.015% of P, less than or equal to 0.015% of S, more than or equal to 0.020% of Al, 0.05-0.10% of Ti, less than or equal to 0.03% of Cr, and less than or equal to 0.02% of Ni; cu is less than or equal to 0.04 percent, and the balance is Fe and inevitable impurities; comprises the following production steps: converter-LF stove-slagging off-LF stove-RH stove-continuous casting. The converter adopts a double-slag method for smelting, high-temperature and high-alkalinity steel tapping, the content of molten steel S at the end point is reduced, ferrosilicon and ferrotitanium are adopted for removing oxygen in the molten steel during the steel tapping of the converter and the LF furnace, aluminum pellets are adopted for removing oxygen in slag, and the molten steel is stirred in combination with large argon gas, so that the molten steel is rapidly desulfurized. The process does not adopt aluminum wire deoxidation under the condition of not pre-treating and desulfurizing molten iron, and can greatly reduce molten steel Al2O3Inclusion and improvement of castability of molten steel.

Description

Method for producing industrial pure iron
Technical Field
The invention relates to a steel material in the field of metallurgy, in particular to a method for producing industrial pure iron by adopting an oxygen converter and external refining process.
Background
Industrial pure iron is an important steel base material, and is generally used for manufacturing aerospace, military and civil alloys or steels such as electromagnetic components, soft magnetic materials, high temperature alloys, heat resistant alloys, precision alloys, maraging steels and the like. At present, the smelting of ultra-low carbon steel industrial pure iron in the prior art mainly comprises two processes: the first is molten iron pretreatment, converter blowing, RH vacuum treatment and continuous casting process; the second is converter blowing-LF refining-RH vacuum treatment-continuous casting process. The second process is to perform aluminum-adding deoxidation, slagging and desulfurization operation in LF, and to control the carbon content in molten steel by adopting forced decarburization in RH vacuum treatment, and the process can cause molten steel Al in the RH treatment process2O3The impurities are more, the flocculation flow of a water gap in the casting process of the molten steel is finally influenced, and the quality and the smooth production of the molten steel are influenced.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a method for producing high-purity industrial pure iron, which can realize molten steelQuick desulfurization; slagging-off can reduce silicon return and sulfur return of later molten steel; without aluminum wire deoxidation, Al in molten steel can be greatly reduced2O3Inclusion and improvement of castability of molten steel.
The invention is realized by the following technical scheme:
the method for producing the industrial pure iron comprises the following chemical compositions in percentage by weight of less than or equal to 0.01% of C, less than or equal to 0.04% of Si, less than or equal to 0.10% of Mn, less than or equal to 0.015% of P, less than or equal to 0.015% of S, more than or equal to 0.020% of Al, 0.05-0.10% of Ti, less than or equal to 0.03% of Cr, and less than or equal to 0.02% of Ni; cu is less than or equal to 0.04 percent, and the balance is Fe and inevitable impurities; comprises the following production steps:
1) converter: adopting molten iron with S less than or equal to 0.030 percent, Mn less than or equal to 0.20 percent, Ni less than 0.02 percent and Cu less than 0.03 and special scrap steel, operating the converter by adopting a double-slag method, and obtaining final slag alkalinity CaO/SiO2The steel tapping temperature is 1640-1660 ℃, the steel tapping temperature is 0.03-0.05 percent of C, 600-1000 ppm of oxygen determination, less than or equal to 0.012 percent of P, less than or equal to 0.020 percent of S, and less than or equal to 0.06 percent of Mn; and (3) stopping slag by adopting a sliding plate during tapping, adding 2.0-3.5 kg/t of steel of lime and 1-2 kg/t of steel of synthetic slag during tapping for slagging, and adding 1.5-2.5 kg/t of steel of ferrosilicon according to tapping oxygen determination for deoxidation.
2) And (4) LF furnace: after molten steel enters a station, removing oxygen in the molten steel by adopting ferrotitanium, removing oxygen in slag by adopting aluminum pills, and adding 0.3-0.6 kg/t of steel into the aluminum pills in multiple batches; stirring and desulfurizing by combining with argon, and adding lime 2.0-4.0 kg/t steel for thick slag when the Si content of the molten steel is less than 0.025 percent and the S content is less than or equal to 0.008 percent.
3) Slagging off: and after the molten steel reaches the slag removing station, removing slag until the exposed surface of the molten steel is more than or equal to 90%, and finishing slag removing operation.
4) And (4) LF furnace: and after slagging off, feeding the molten steel into an LF furnace again for heating and slagging operation, adding lime, pre-melted slag and aluminum balls for slagging, wherein the adding amount of the lime is 4-6 kg/t of steel, the adding amount of the pre-melted slag is 1.5-3.0 kg/t of steel, the adding amount of fluorite is 0-2.0 kg/t of steel, and the FeO content of the final slag is less than or equal to 2.0%.
5) RH furnace: after the molten steel enters RH, controlling the carbon content in the molten steel by adopting a forced decarburization mode, and finishing decarburization when the oxygen content of the molten steel is 200-300 ppm, wherein the C content of the molten steel is less than or equal to 0.004%; then, circulating deoxidation and alloying are carried out, and the argon blowing flow is 115-125Nm3H, adding 0.95-1.15 kg/t of aluminum iron, circulating for 3-4 min, adding 1.3-1.5 kg/t of ferrotitanium (Ti content is 70%), and circulatingBreaking the blank in 3-4 minutes; feeding a pure calcium wire with the thickness of 200-300 m after the blank is broken, soft blowing for 8-15 min, uniformly spraying 30-40 kg of aluminum balls on the slag surface, and then casting on the bench.
6) Continuous casting: the casting process adopts a carbon-free covering agent and carbon-free covering slag to prevent recarburization in the casting process, the continuous casting process adopts full-protection casting, and the superheat degree of the tundish is controlled at 40-60 ℃.
The invention has the beneficial effects that: the converter adopts suitable molten iron and special scrap steel, the contents of elements such as Cr, Ni, Cu, Mn and the like in the steel are effectively controlled, a double-slag method is adopted for smelting, high-temperature and high-alkalinity steel tapping is adopted, the content of molten steel S at the end point is reduced, ferrosilicon and ferrotitanium are adopted for removing oxygen in the molten steel during converter tapping and the LF furnace, aluminum pellets are adopted for removing oxygen in slag, and large argon gas is combined for stirring, so that the rapid desulfurization of the molten steel is realized. The slag skimming can reduce the silicon return and sulfur return of the molten steel in the later period. The process does not adopt aluminum wire deoxidation under the condition of not pre-treating and desulfurizing molten iron, and can greatly reduce Al in molten steel2O3Inclusion and improvement of castability of molten steel.
Detailed Description
The present invention will be further described with reference to the following examples.
Example 1
A method for producing industrial pure iron, the chemical composition of the steel is shown in Table 1, comprising the following production steps:
1) converter: selecting proper molten iron and special scrap steel, and adding the following components in molten iron: s = 0.028%, Mn = 0.17%, Ni = 0.01%, Cu =0.02%, and the method adopts a double-slag method operation during smelting, and the final slag alkalinity is CaO/SiO2=4.8, the tapping temperature is 1648 ℃, the tapping C =0.042%, the oxygen is determined to be 752ppm, the tapping P = 0.011%, S = 0.017% and Mn = 0.06%. The steel tapping adopts a sliding plate to block slag, lime 2.7kg/t steel and synthetic slag 1.3kg/t steel are added in the steel tapping process, and ferrosilicon 1.8kg/t steel is added according to the determined oxygen for steel tapping to perform deoxidation.
2) And (4) LF furnace: after molten steel enters a station, 1.1 kg/t ferrotitanium is added to remove oxygen in the molten steel, and 0.42kg/t ferrotitanium is added in a plurality of batches and in a small amount to remove oxygen in slag. Stirring and desulfurizing in combination with argon, adding lime 2.7kg/t steel when Si = 0.018% and S = 0.006% of molten steel for thick slag, and then carrying out slag removal operation.
3) Slagging off: and after the molten steel reaches the slag removing station, removing slag until the exposed surface of the molten steel is more than or equal to 90%, and completing slag removing operation.
4) And (4) LF furnace: after slagging off, the molten steel enters the LF again to carry out heating slagging operation, and 4.5kg/t of steel with lime, 2.0kg/t of pre-melted slag, 1.2 kg/t of fluorite and 1.65% of FeO in the final slag are added.
5) RH furnace: and (2) after the molten steel enters RH, oxygen blowing for decarburization is adopted, circulation is carried out for 12min after the oxygen blowing is finished, when the oxygen content of the molten steel is 252ppm, the C content of the molten steel is 0.002%, the argon blowing flow is increased to be controlled at 120Nm3/h, 0.105Kg/t of steel of aluminum is added, 1.4Kg/t of steel of ferrotitanium (Ti = 70%) is added in circulation for 3min, and the molten steel is broken after circulation for 4 min. Feeding a pure calcium wire of 250m after breaking the cavity, soft blowing for 12min, spraying 35Kg of aluminum balls on the slag surface, and then casting on the bench.
6) Continuous casting: the casting process adopts a carbon-free covering agent and carbon-free covering slag to prevent recarburization in the casting process, the process adopts full-protection casting to reduce the nitrogen increase and secondary oxidation of molten steel, and the superheat degree of a tundish is controlled at 51-55 ℃. The liquid level of the crystallizer is controlled within +/-5 mm in the casting process.
Example 2
A method for producing industrial pure iron, the chemical composition of the steel is shown in Table 1, comprising the following production steps:
1) converter: selecting proper molten iron and special scrap steel, and adding the following components in molten iron: s =0.025%, Mn = 0.18%, Ni = 0.01%, Cu =0.02%, and the method is operated by a double-slag method during smelting, and the final slag alkalinity is CaO/SiO2=5.3, 1655 ℃ tapping temperature, tapping C =0.032%, fixing oxygen 902ppm, tapping P = 0.010%, S =0.015%, Mn = 0.05%. The steel tapping adopts a sliding plate to block slag, lime 3.2kg/t steel and synthetic slag 1.5kg/t steel are added in the steel tapping process, and ferrosilicon 2.2kg/t steel is added according to the determined oxygen for steel tapping to perform deoxidation.
2) And (4) LF furnace: after molten steel enters a station, 1.3kg/t of ferrotitanium is added to remove oxygen in the molten steel, and 0.53kg/t of aluminum shot is added in a plurality of batches and in a small amount to remove oxygen in slag. Stirring and desulfurizing in combination with argon, adding lime 3.2kg/t steel for thick slag when Si = 0.013% and S =0.007% of molten steel, and then carrying out slag skimming operation.
3) Slagging off: and after the molten steel reaches the slag removing station, removing slag until the exposed surface of the molten steel is more than or equal to 90%, and completing slag removing operation.
4) And (4) LF furnace: and after slagging off, the molten steel enters the LF again to carry out temperature rise slagging operation, 5.2kg/t steel of lime is added, 2.8kg/t steel of pre-melted slag is added, and FeO of final slag is = 1.52%.
5) RH furnace: after molten steel enters RH, oxygen blowing decarburization is adopted, circulation is carried out for 12min after oxygen blowing is finished, when oxygen is determined to be 289ppm in the molten steel, the molten steel C = 0.002%, and the argon blowing flow is improved to be controlled to be 120Nm3And h, adding 0.110kg of aluminum iron/t steel, circulating for 3min, adding 1.4kg of titanium iron (Ti = 70%) per t steel, and circulating for 4min and then breaking the air. After the air is broken, a pure calcium wire is fed for 220m, soft blowing is carried out for 10min, and 35kg of aluminum balls are sprayed on the slag surface and then cast on the bench.
6) Continuous casting: the casting process adopts a carbon-free tundish, a carbon-free covering agent and carbon-free covering slag to prevent recarburization in the casting process, full-protection casting is adopted to reduce nitrogen increase and secondary oxidation of molten steel, and the superheat degree of the tundish is controlled at 42-46 ℃. The liquid level of the crystallizer is controlled within +/-5 mm in the casting process.
Table 1 chemical composition of example steels (wt,%)

Claims (1)

1. The method for producing the industrial pure iron comprises the following chemical compositions in percentage by weight of less than or equal to 0.01% of C, less than or equal to 0.04% of Si, less than or equal to 0.10% of Mn, less than or equal to 0.015% of P, less than or equal to 0.015% of S, more than or equal to 0.020% of Al, 0.05-0.10% of Ti, less than or equal to 0.03% of Cr, and less than or equal to 0.02% of Ni; cu is less than or equal to 0.04 percent, and the balance is Fe and inevitable impurities; comprises the following production steps:
1) converter: adopting molten iron with S less than or equal to 0.030 percent, Mn less than or equal to 0.20 percent, Ni less than 0.02 percent and Cu less than 0.03 and special scrap steel, operating the converter by adopting a double-slag method, and obtaining final slag alkalinity CaO/SiO2The steel tapping temperature is 1640-1660 ℃, the steel tapping temperature is 0.03-0.05 percent of C, 600-1000 ppm of oxygen determination, less than or equal to 0.012 percent of P, less than or equal to 0.020 percent of S, and less than or equal to 0.06 percent of Mn; the steel tapping adopts a sliding plate to block slag, 2.0-3.5 kg/t of steel of lime and 1-2 kg/t of steel of synthetic slag are added in the steel tapping process for slagging, and 1.5-2.5 kg/t of steel of ferrosilicon is added according to the determined oxygen in the steel tapping for deoxidation;
2) and (4) LF furnace: after molten steel enters a station, removing oxygen in the molten steel by adopting ferrotitanium, removing oxygen in slag by adopting aluminum pills, and adding 0.3-0.6 kg/t of steel into the aluminum pills in multiple batches; stirring and desulfurizing by combining with argon, and adding lime 2.0-4.0 kg/t steel for thick slag when the Si content of the molten steel is less than 0.025 percent and the S content is less than or equal to 0.008 percent;
3) slagging off: after the molten steel reaches a slagging-off station, slagging-off is carried out until the exposed surface of the molten steel is more than or equal to 90%, and slagging-off operation is finished;
4) and (4) LF furnace: after slagging off, feeding the molten steel into an LF furnace again for heating and slagging operation, adding lime, pre-melted slag and aluminum pellets for slagging, wherein the adding amount of the lime is 4-6 kg/t of steel, the adding amount of the pre-melted slag is 1.5-3.0 kg/t of steel, the adding amount of fluorite is 0-2.0 kg/t of steel, and the FeO content of the final slag is less than or equal to 2.0%;
5) RH furnace: after the molten steel enters RH, controlling the carbon content in the molten steel by adopting a forced decarburization mode, and finishing decarburization when the oxygen content of the molten steel is 200-300 ppm, wherein the C content of the molten steel is less than or equal to 0.004%; then, circulating deoxidation and alloying are carried out, and the argon blowing flow is 115-125Nm3Adding 0.95-1.15 kg/t of aluminum iron into steel, circulating for 3-4 min, adding 1.3-1.5 kg/t of ferrotitanium (the Ti content is 70%), circulating for 3-4 min, and breaking the air; feeding a pure calcium wire with the thickness of 200-300 m after the blank is broken, soft blowing for 8-15 min, uniformly spraying 30-40 kg of aluminum balls on the slag surface, and then casting on the bench;
6) continuous casting: the casting process adopts a carbon-free covering agent and carbon-free covering slag to prevent recarburization in the casting process, the continuous casting process adopts full-protection casting, and the superheat degree of the tundish is controlled at 40-60 ℃.
CN202110337726.4A 2021-03-30 2021-03-30 Method for producing industrial pure iron Pending CN113215476A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113621868A (en) * 2021-08-12 2021-11-09 山西太钢不锈钢股份有限公司 Smelting method of low-phosphorus low-aluminum base steel for high-speed rail wheel

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113621868A (en) * 2021-08-12 2021-11-09 山西太钢不锈钢股份有限公司 Smelting method of low-phosphorus low-aluminum base steel for high-speed rail wheel

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