CN110042189B - Converter slagging method for efficiently dephosphorizing - Google Patents
Converter slagging method for efficiently dephosphorizing Download PDFInfo
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- CN110042189B CN110042189B CN201910312314.8A CN201910312314A CN110042189B CN 110042189 B CN110042189 B CN 110042189B CN 201910312314 A CN201910312314 A CN 201910312314A CN 110042189 B CN110042189 B CN 110042189B
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- converter
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- oxygen supply
- slag
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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
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/02—Dephosphorising or desulfurising
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/36—Processes yielding slags of special composition
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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
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/064—Dephosphorising; Desulfurising
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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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- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
Abstract
The invention relates to a converter slagging method for efficiently dephosphorizingThe method comprises the following steps: after waste steel and molten iron are loaded into the converter, lime and magnesite are added into the converter according to the content of silicon element in the molten iron; adding ferrosilicon and magnesite into the furnace in the middle and later periods of oxygen supply, properly increasing the gun position, and adding SiO2React with CaO in the slag to form 2 CaO. SiO2The later dephosphorization capability of the slag is improved, and the magnesite added at the time can prevent SiO in the slag2The furnace lining erosion caused by the increased content has good market application prospect.
Description
Technical Field
The invention belongs to the field of steel smelting, and particularly relates to a converter slagging method for efficiently dephosphorizing.
Background
In the process of converter oxygen top-bottom combined blowing steelmaking, alkaline slag is required to be produced to absorb oxidation reaction products of impurity elements in molten steel, especially P produced by dephosphorization2O5Needs to be combined with the components in the slag for real removal. The conventional converter steelmaking slagging process is to add slagging raw materials such as active lime, light burned dolomite and the like at one time in the early stage of converter blowing, and has the main problems that: (1) the melting rate of the slag-forming material is limited, and the early dephosphorization process of the converter is restricted; (2) the dephosphorization effect in the later period of the converter smelting is greatly reduced, and even the rephosphorization phenomenon occurs.
Disclosure of Invention
The invention aims to solve the technical problem of providing a converter slagging method for efficiently dephosphorizing, which is characterized in that ferrosilicon and magnesite are added into a converter at the middle and later stages of converter blowing on the premise of meeting the final slag parameter of converter smelting, rephosphorization is controlled to improve the dephosphorization rate of the converter, a furnace lining is protected, and the converter smelting cost is greatly reduced.
The invention provides a converter slagging method for efficient dephosphorization, which comprises the following steps:
charging scrap steel and molten iron according to the nominal capacity of the converter:
when the oxygen supply amount is 10-25%, 30-60kg of lime and 10-15kg of magnesite are added into the furnace according to the content of silicon element in molten iron, the lance position of the oxygen lance is controlled to be 1.8-1.9m, and the oxygen supply intensity is controlled to be 3.0-3.5Nm3/(min. t), the intensity of bottom-blown gas is 0.03-0.06Nm3/(min·t)；
When the oxygen supply amount is 70-80%, 2-4 kg/ton steel of Fe-75Si ferrosilicon and 2-3 kg/ton steel of magnesite are added into the furnace, and simultaneously the lance position of the oxygen lance is controlled at 2.4-2.6m, and the oxygen supply intensity is controlled at 3.0-3.8Nm3/(min. t), the bottom-blowing gas supply intensity is 0.05-0.08Nm3/(min·t)；
And controlling the alkalinity and the main components of the slag at the end point of the converter, finishing converting and carrying out tapping operation.
Further, nitrogen is blown at the bottom when oxygen supply is 0-75 percent in the converting process, argon is blown at the bottom when oxygen supply is 75-100 percent, and the gas supply intensity of bottom blowing is 0.03-0.06Nm3/(min·t)。
Further, the oxygen lance position is controlled to be 1.8-1.9m when the oxygen supply amount is 0-10%, and the oxygen supply intensity is controlled to be 3.0-3.5Nm3/(min·t)。
Furthermore, the granularity of the magnesite and the Fe-75Si ferrosilicon is 10-40 mm.
Further, the alkalinity of the converter end point slag is controlled to be 3.0-3.5.
Further, the main components of the converter terminal slag are controlled as follows: 7-12% of FeO, 38-45% of CaO and SiO212-25% of mass fraction, 12-20% of MgO mass fraction, and the balance being controlled according to conventional converter slag component and content level.
The key points of the invention are as follows:
adding ferrosilicon and magnesite into the furnace in the middle and later periods of oxygen supply, properly increasing the gun position, and adding SiO2React with CaO in the slag to form 2 CaO. SiO2And the strength of low-blowing gas is properly improved, 2 CaO. SiO in the slag2Can be reacted with P2O5The combination improves the dephosphorization capability of the slag in the later period and prevents rephosphorization. And the magnesite added at the same time can be rapidly decomposed to form MgO and release CO2Gas, not only can increase dynamic conditions to promote 2 CaO. SiO2Generating and reacting with P2O5The combination can also play the role of protecting the furnace lining, and prevent the added silicon from promoting the furnace lining to be corroded.
Advantageous effects
In the invention, ferrosilicon and magnesite are added into the furnace in the middle and later stages of converting to increase 2CaO SiO in the slag2The content of the magnesite is prevented from rephosphorization, the later-stage dephosphorization capability of the converter is improved, the dephosphorization rate of the converter can reach more than 90%, meanwhile, the magnesite added into the converter in the middle and later stages of blowing can effectively reduce the erosion of the furnace slag to the furnace lining, the service life of the furnace lining of the converter is prolonged by 3-6%, the raw and auxiliary material cost of the converter is greatly reduced, and the method has good market application prospect.
Detailed Description
The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.
Example 1
A180-ton top-bottom combined blown converter is adopted for smelting, the silicon content of molten iron is 0.35 percent, the phosphorus content of the molten iron is 0.14 percent, and the smelting process mainly comprises the following steps:
30t of scrap steel and 185t of molten iron are transferred into a converter;
bottom blowing nitrogen during oxygen supply of 0-75%, bottom blowing argon during oxygen supply of 75-100%, and bottom blowing strong gas supplyDegree of 0.03Nm3V (min. t); the oxygen lance position is controlled at 1.9m and the oxygen supply intensity is controlled at 3.0Nm during the oxygen supply amount is 0-10 percent3/(min·t)；
When the oxygen supply amount is 12 percent, adding lime 7.2t and magnesite 2.2t into the furnace, simultaneously controlling the lance position of an oxygen lance at 1.9m and controlling the oxygen supply intensity at 3.0Nm3/(min·t)；
When the oxygen supply amount is 78%, 0.45t of Fe-75Si ferrosilicon and 0.45t of magnesite are added into the furnace, meanwhile, the lance position of the oxygen lance is controlled to be 2.0m, and the oxygen supply intensity is controlled to be 3.0Nm3/(min. t), bottom-blowing gas supply intensity of 0.05Nm3/(min·t)；
The alkalinity of the converter end-point slag is controlled to be 3.1, and the main components in the slag are controlled as follows: 17-19 percent of FeO, 39 percent of CaO and SiO212.6 percent of mass fraction, 7 to 12 percent of MgO mass fraction, and the rest part is controlled according to the components and content level of the slag of the conventional converter.
And finally, ending the blowing and carrying out tapping operation.
After slagging and smelting are carried out by the embodiment, the dephosphorization rate of molten steel reaches 92 percent, and the converter steelmaking cost is reduced by about 3.5 yuan/t steel.
Example 2
A180-ton top-bottom combined blown converter is adopted for smelting, the silicon content of molten iron is 0.36 percent, the phosphorus content of the molten iron is 0.14 percent, and the smelting process mainly comprises the following steps:
transferring into a converter for 28t of scrap steel and 187t of molten iron;
the nitrogen is supplied in the whole bottom blowing process in the blowing process, and the air supply intensity of the bottom blowing is 0.03Nm3V (min. t); the oxygen lance position is controlled at 1.9m and the oxygen supply intensity is controlled at 3.0Nm during the oxygen supply amount is 0-10 percent3/(min·t)；
When the oxygen supply amount is 12 percent, adding lime 7.5t and magnesite 2.3t into the furnace, simultaneously controlling the lance position of an oxygen lance at 1.9m and controlling the oxygen supply intensity at 3.0Nm3/(min·t)；
When the oxygen supply amount is 75-78%, adding 0.45t of Fe-75Si ferrosilicon and 0.45t of magnesite into the furnace, simultaneously controlling the lance position of the oxygen lance to be 2.0m, and controlling the oxygen supply intensity to be 3.0Nm3/(min. t), bottom-blowing gas supply intensity of 0.05Nm3/(min·t)；
The alkalinity of the converter end-point slag is controlled to be 3.15, and the main components in the slag are controlled as follows: 17-19 percent of FeO, 39 percent of CaO and SiO212.3 percent of mass fraction, 7 to 12 percent of MgO mass fraction, and the rest part is controlled according to the components and content level of the conventional converter slag.
And finally, ending the blowing and carrying out tapping operation.
After slagging and smelting are carried out by the embodiment, the dephosphorization rate of molten steel reaches 90 percent, and the converter steelmaking cost is reduced by about 2.5 yuan/t steel.
Claims (6)
1. A converter slagging method for efficiently dephosphorizing comprises the following steps:
charging scrap steel and molten iron according to the nominal capacity of the converter:
when the oxygen supply amount is 10-25%, 30-60kg of lime and 10-15kg of magnesite are added into the furnace according to the content of silicon element in molten iron, the lance position of the oxygen lance is controlled to be 1.8-1.9m, and the oxygen supply intensity is controlled to be 3.0-3.5Nm3/(min. t), the intensity of bottom-blown gas is 0.03-0.06Nm3/(min·t)；
When the oxygen supply amount is 70-80%, 2-4 kg/ton steel of Fe-75Si ferrosilicon and 2-3 kg/ton steel of magnesite are added into the furnace, and simultaneously the lance position of the oxygen lance is controlled at 1.9-2.0m, and the oxygen supply intensity is controlled at 3.0-3.5Nm3/(min. t), the bottom-blowing gas supply intensity is 0.05-0.08Nm3/(min·t)；
And controlling the alkalinity and the main components of the slag at the end point of the converter, finishing converting and carrying out tapping operation.
2. The method for slagging in a converter with efficient dephosphorization according to claim 1, wherein the method comprises the following steps: in the blowing process, nitrogen is blown at the bottom when the oxygen supply is 0-75 percent, argon is blown at the bottom when the oxygen supply is 75-100 percent, and the gas supply intensity of bottom blowing is 0.03-0.06Nm3V (min. t); or bottom blowing argon in the whole blowing process, wherein the bottom blowing gas supply intensity is 0.05-0.08Nm3/(min·t)。
3. The method for slagging in a converter with efficient dephosphorization according to claim 1, wherein the method comprises the following steps: oxygen lance position control when oxygen supply is 0% -10%Prepared at 1.8-1.9m, and oxygen supply intensity is controlled at 3.0-3.5Nm3/(min·t)。
4. The method for slagging in a converter with efficient dephosphorization according to claim 1, wherein the method comprises the following steps: the particle sizes of the magnesite and the Fe-75Si ferrosilicon are both 10-40 mm.
5. The method for slagging in a converter with efficient dephosphorization according to claim 1, wherein the method comprises the following steps: and the alkalinity of the converter end point slag is controlled to be 3.0-3.5.
6. The method for slagging in a converter with efficient dephosphorization according to claim 1, wherein the method comprises the following steps: the main components of the converter end point slag are controlled as follows: 7-12% of FeO, 38-45% of CaO and SiO212-25% of mass fraction, 12-20% of MgO mass fraction, and the balance being controlled according to conventional converter slag component and content level.
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| CN201910312314.8A CN110042189B (en) | 2019-04-18 | 2019-04-18 | Converter slagging method for efficiently dephosphorizing |
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| CN110042189B true CN110042189B (en) | 2021-01-12 |
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| CN111154941B (en) * | 2020-02-28 | 2021-07-20 | 鞍钢股份有限公司 | 9 nickel steel smelting iron adding dust escape prevention method |
| CN111363882A (en) * | 2020-03-31 | 2020-07-03 | 宁波钢铁有限公司 | Slagging method for prolonging service life of converter lining |
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| US4462823A (en) * | 1982-12-11 | 1984-07-31 | Foseco International Limited | Treatment agents for molten steel |
| CN106148630B (en) * | 2015-03-26 | 2018-06-26 | 上海梅山钢铁股份有限公司 | A kind of method of the low-phosphorous low-sulfur molten steel of converter smelting |
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