CN117535464A - Low-carbon steelmaking method and system using low-grade direct reduced iron as raw material - Google Patents
Low-carbon steelmaking method and system using low-grade direct reduced iron as raw material Download PDFInfo
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- CN117535464A CN117535464A CN202311362258.1A CN202311362258A CN117535464A CN 117535464 A CN117535464 A CN 117535464A CN 202311362258 A CN202311362258 A CN 202311362258A CN 117535464 A CN117535464 A CN 117535464A
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 183
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 52
- 238000000034 method Methods 0.000 title claims abstract description 52
- 239000002994 raw material Substances 0.000 title claims abstract description 31
- 238000009628 steelmaking Methods 0.000 title claims abstract description 28
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 69
- 239000010959 steel Substances 0.000 claims abstract description 69
- 238000002844 melting Methods 0.000 claims abstract description 61
- 230000008018 melting Effects 0.000 claims abstract description 61
- 229910052742 iron Inorganic materials 0.000 claims abstract description 54
- 239000002893 slag Substances 0.000 claims abstract description 44
- 238000007670 refining Methods 0.000 claims abstract description 28
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 27
- 238000003723 Smelting Methods 0.000 claims abstract description 27
- 239000007788 liquid Substances 0.000 claims abstract description 22
- 238000009749 continuous casting Methods 0.000 claims abstract description 21
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000001257 hydrogen Substances 0.000 claims abstract description 16
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 16
- 238000005266 casting Methods 0.000 claims abstract description 11
- 238000010438 heat treatment Methods 0.000 claims abstract description 7
- 239000002436 steel type Substances 0.000 claims abstract description 4
- 238000010891 electric arc Methods 0.000 claims description 22
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 17
- 238000007664 blowing Methods 0.000 claims description 10
- 229910052786 argon Inorganic materials 0.000 claims description 9
- 239000000463 material Substances 0.000 claims description 5
- 238000009826 distribution Methods 0.000 claims description 3
- 239000013589 supplement Substances 0.000 claims 1
- 238000011031 large-scale manufacturing process Methods 0.000 abstract description 4
- 241001062472 Stokellia anisodon Species 0.000 abstract description 3
- 238000005272 metallurgy Methods 0.000 abstract description 2
- 230000008569 process Effects 0.000 description 32
- 238000010079 rubber tapping Methods 0.000 description 18
- 238000004519 manufacturing process Methods 0.000 description 17
- 230000009467 reduction Effects 0.000 description 10
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 6
- 239000001301 oxygen Substances 0.000 description 6
- 229910052760 oxygen Inorganic materials 0.000 description 6
- 238000005261 decarburization Methods 0.000 description 5
- 239000008188 pellet Substances 0.000 description 5
- 229910052698 phosphorus Inorganic materials 0.000 description 4
- 230000005611 electricity Effects 0.000 description 3
- 239000003345 natural gas Substances 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 229910052717 sulfur Inorganic materials 0.000 description 3
- 230000007812 deficiency Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000010309 melting process Methods 0.000 description 2
- 238000001465 metallisation Methods 0.000 description 2
- 238000009842 primary steelmaking Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- FGUUSXIOTUKUDN-IBGZPJMESA-N C1(=CC=CC=C1)N1C2=C(NC([C@H](C1)NC=1OC(=NN=1)C1=CC=CC=C1)=O)C=CC=C2 Chemical compound C1(=CC=CC=C1)N1C2=C(NC([C@H](C1)NC=1OC(=NN=1)C1=CC=CC=C1)=O)C=CC=C2 FGUUSXIOTUKUDN-IBGZPJMESA-N 0.000 description 1
- YZCKVEUIGOORGS-OUBTZVSYSA-N Deuterium Chemical compound [2H] YZCKVEUIGOORGS-OUBTZVSYSA-N 0.000 description 1
- 241001417490 Sillaginidae Species 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- CSJDCSCTVDEHRN-UHFFFAOYSA-N methane;molecular oxygen Chemical compound C.O=O CSJDCSCTVDEHRN-UHFFFAOYSA-N 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B11/00—Making pig-iron other than in blast furnaces
- C21B11/10—Making pig-iron other than in blast furnaces in electric furnaces
-
- 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
- C21C5/30—Regulating or controlling the blowing
-
- 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
- C21C5/52—Manufacture of steel in electric furnaces
-
- 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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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacture Of Iron (AREA)
Abstract
The invention relates to a low-carbon steelmaking method and a system using low-grade direct reduced iron as a raw material, belonging to the technical field of metallurgy, and comprising the following steps: s1, obtaining a direct reduced iron raw material from a hydrogen-based shaft furnace; s2, loading the direct reduced iron raw material into an electric melting furnace through hot feeding or cold feeding; s3, electrifying and heating in the electric melting furnace, adding a slag former, creating a reducing atmosphere to directly reduce iron, reducing and melting, and separating liquid molten iron and liquid slag; s4, transferring the liquid molten iron into an arc furnace or a converter for converting into primary molten steel, and directly casting the primary molten steel on a continuous casting machine according to the steel type requirement or refining the primary molten steel by a refining device and then casting the primary molten steel on the continuous casting machine, wherein molten iron slag and steel slag are both transported to a slag treatment plant for treatment. The invention realizes the smelting of low-grade direct reduced iron, solves the problem that the prior art cannot smelt low-grade direct reduced iron in a large scale, can replace a long-flow steelmaking process of a blast furnace, has low carbon emission, and is suitable for large-scale production.
Description
Technical Field
The invention belongs to the technical field of metallurgy, and relates to a low-carbon steelmaking method and a system using low-grade direct reduced iron as a raw material.
Background
The traditional iron and steel industry is a resource, energy, technology, capital intensive industry, and is also a typical high carbon emissions industry. In the whole steel process, the carbon emission of the smelting process is more than 95% of the whole steel process, so the carbon reduction of the steel smelting process is important.
Combines the current steel industry production structure, smelting raw material supply, smelting energy, energy conservation and emission reduction level and CO 2 The main process of iron and steel production in the next thirty years still is the coexistence of a long process and a short process, the short process is rapidly developed, the raw materials of the long process are optimized, particularly, the iron making process in the long process is gradually changed from carbon reduction to hydrogen reduction, and the product of the iron making process is changed from the original high-carbon molten iron to direct reduced iron, so that the method is an important way for low-carbon transformation in the iron and steel industry. According to statistics of a long-flow process of a blast furnace and a converter, smelting CO of each ton of molten steel based on coke/coal 2 About (1.8-2.0) t is discharged. Adopts a short-flow process of 'shaft furnace + electric arc furnace', and smelts CO per ton of molten steel based on natural gas 2 About 0.94t is discharged, and CO is smelted per ton of molten steel based on hydrogen 2 About 0.47t of emission, CO can be realized based on hydrogen and using green hydrogen and green electricity 2 Near zero emission.
In the long-process iron-making process, the gradual reduction from carbon to hydrogen is a trend, the product of the iron-making process is changed from the original high-carbon molten iron into direct reduced iron, but the conventional electric arc furnace is used for smelting the direct reduced iron at present, the requirement on the grade of the direct reduced iron is high, the method is suitable for the electric arc furnace to smelt the direct reduced iron produced by low-grade ores with high-grade ores accounting for about 6% of the global ore reserves, and the ore reserves accounting for over 90% have the problems that the slag quantity is large, the electric arc furnace cannot normally operate, the smelting period is long, the production cost is high and the like.
Disclosure of Invention
In view of the above, the present invention aims to provide a low-carbon steelmaking method and system using low-grade direct reduced iron as a raw material, so as to achieve the purpose.
In order to achieve the above purpose, the present invention provides the following technical solutions:
a low-carbon steelmaking method taking low-grade direct reduced iron as a raw material comprises the following steps:
s1, obtaining a direct reduced iron raw material from a hydrogen-based shaft furnace;
s2, loading the direct reduced iron raw material into an electric melting furnace through hot feeding or cold feeding;
s3, electrifying and heating in the electric melting furnace, adding a slag former, creating a reducing atmosphere to directly reduce iron, reducing and melting, and separating liquid molten iron and liquid slag;
s4, transferring the liquid molten iron into an arc furnace or a converter for converting into primary molten steel, and directly casting the primary molten steel on a continuous casting machine according to the steel type requirement or refining the primary molten steel by a refining device and then casting the primary molten steel on the continuous casting machine, wherein molten iron slag and steel slag are both transported to a slag treatment plant for treatment.
Optionally, in step S1, directly reduced iron ore is produced as low and medium grade iron ore with T.Fe less than or equal to 65%.
Alternatively, the size of the direct reduced iron produced in step S1 is not limited.
Optionally, in the step S3, slag formers are added at the edge of the furnace wall of the electric melting furnace in a multipoint distribution manner, and a cold area is formed at the edge, so that the wall-mounted slag and submerged arc smelting of the furnace and the smelting operation of a large amount of slag are realized.
Optionally, in step S3, the power density in the hearth of the electric melting furnace is less than 0.5MVA/m2
Optionally, the temperature of the electric melting furnace is controlled between 1450 ℃ and 1600 ℃.
Optionally, in step S4, the heat deficiency is compensated by adding a carburant when the liquid molten iron is tapped through the converter, and the heat deficiency is compensated by electrifying and heating when the liquid molten iron is tapped through the electric arc furnace.
Optionally, in the step S2, the transportation mode of the hot direct reduced iron is a pneumatic conveying device, a closed charging bucket or a high-temperature chain plate machine, and the transportation mode of the cold direct reduced iron or the HBI is an automobile or a belt conveyor.
A low-carbon steelmaking system taking low-grade direct reduced iron as a raw material comprises a hydrogen-based shaft furnace, an electric melting furnace, an electric arc furnace or a converter and a continuous casting machine, wherein the hydrogen-based shaft furnace, the electric melting furnace, the electric arc furnace or the converter and the continuous casting machine are sequentially arranged along the flow direction of materials, the hydrogen-based shaft furnace is used for producing the direct reduced iron, the electric melting furnace is used for melting the direct reduced iron to separate liquid molten iron and liquid slag, the electric arc furnace or the converter is used for smelting the liquid molten iron into molten steel, and the continuous casting machine is used for casting the molten steel.
Optionally, a refining device is arranged between the electric arc furnace or the converter and the continuous casting machine, and the refining device is any one or more of an argon blowing wire feeding station, an LF or a RH, VD, VOD.
The invention has the beneficial effects that:
1. the smelting of low-grade direct reduced iron is realized, the problem that the low-grade direct reduced iron cannot be smelted in a large proportion in the prior art is solved, and the low-grade ore which is originally only used for a long-process blast furnace can also be produced by adopting the invention, so that the low-grade ore can replace the long-process steelmaking of the blast furnace.
2. The invention does not adopt molten iron as raw material, can effectively reduce carbon emission in the steel production process, and has limit carbon emission close to zero.
3. The invention can replace a blast furnace, and simultaneously can utilize the existing converter to make steel, thereby saving investment.
4. The invention is suitable for the existing converter or arc furnace production technology and is suitable for large-scale production.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and other advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the specification.
Drawings
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in the following preferred detail with reference to the accompanying drawings, in which:
FIG. 1 is a flow chart of a low-carbon steelmaking process using low-grade direct reduced iron as a raw material.
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention. It should be noted that the illustrations provided in the following embodiments merely illustrate the basic idea of the present invention by way of illustration, and the following embodiments and features in the embodiments may be combined with each other without conflict.
Wherein the drawings are for illustrative purposes only and are shown in schematic, non-physical, and not intended to limit the invention; for the purpose of better illustrating embodiments of the invention, certain elements of the drawings may be omitted, enlarged or reduced and do not represent the size of the actual product; it will be appreciated by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
The same or similar reference numbers in the drawings of embodiments of the invention correspond to the same or similar components; in the description of the present invention, it should be understood that, if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc., that indicate an azimuth or a positional relationship based on the azimuth or the positional relationship shown in the drawings, it is only for convenience of describing the present invention and simplifying the description, but not for indicating or suggesting that the referred device or element must have a specific azimuth, be constructed and operated in a specific azimuth, so that the terms describing the positional relationship in the drawings are merely for exemplary illustration and should not be construed as limiting the present invention, and that the specific meaning of the above terms may be understood by those of ordinary skill in the art according to the specific circumstances.
Referring to fig. 1, a low-carbon steelmaking method using low-grade direct reduced iron as a raw material includes the steps of:
a. obtaining a direct reduced iron feedstock from a hydrogen-based shaft furnace;
b. charging directly reduced iron as a raw material into an electric melting furnace through hot feeding or cold feeding;
c. charging hot or cold direct reduced iron into an electric melting furnace for reduction and melting, wherein the electric melting furnace is of a fixed closed type, electrifying and heating, creating a reducing atmosphere, adding a slag forming agent into the furnace, adjusting slag components, and melting and separating liquid molten iron and liquid molten iron slag;
d. transferring the liquid molten iron into a converter or an electric arc furnace for blowing, and smelting the molten iron into qualified molten steel;
e. both molten iron slag and steel slag are transported to a slag treatment plant for treatment;
f. the molten steel is directly cast on a continuous casting machine according to the steel type requirement or is sent to the continuous casting machine for casting after passing through a refining device;
the invention realizes the smelting of low-grade direct reduced iron, solves the problem that the prior art cannot smelt low-grade direct reduced iron in a large scale, can replace a long-flow steelmaking process of a blast furnace, has low carbon emission, and is suitable for large-scale production.
Alternatively, the ore for producing the direct reduced iron in the step a is low and medium grade iron ore with T.Fe less than or equal to 65%.
Alternatively, the size of the direct reduced iron produced in the step a is not limited.
Alternatively, the direct reduced iron hot charging temperature in step b is about 500 ℃.
Optionally, the hot direct reduced iron in the step b can be conveyed to the electric melting furnace by using the pneumatic conveying of the heating gas, and the automobile transportation closed charging bucket is transported to the electric melting furnace and the high-temperature chain scraper is transported to the electric melting furnace; cold direct reduced iron is transported to the electric melting furnace by an automobile or a belt conveyor, direct reduced iron Hot Briquettes (HBI) are transported to the electric melting furnace by an automobile or a belt conveyor, etc.
Optionally, in the step c, the electric melting furnace is in a fixed closed type, and slag holes and iron holes are arranged up and down.
Optionally, in the step c, slag formers are added at the edge of the furnace wall of the electric melting furnace in a multipoint distribution manner, and a cold area is formed at the edge, so that slag hanging and submerged arc (arc blocking) smelting of the furnace are realized, and large-slag smelting operation is realized.
Optionally, the power density in the hearth of the electric melting furnace in the step c<0.5MVA/m 2 。
Optionally, the temperature of the electric melting furnace in the step c is controlled to be 1450-1600 ℃.
Alternatively, a circular electric furnace below 60MW may be used for the electric furnace in step c, with rectangular electric furnaces being recommended for higher than 60 MW.
Optionally, the tapping speed of the electric melting furnace in the step c is 3-4 t/min.
Optionally, in the step d, the converter is used for smelting steel, and 0-30 kg/t of carburant is added in the case of insufficient heat.
Optionally, the refining apparatus in step f comprises any one or more of an argon blowing wire feeding station, LF or RH, VD, VOD.
Example 1
As shown in fig. 1, a low-carbon steelmaking process and equipment adopting low-grade direct reduced iron raw materials, comprising a high-temperature chain plate machine, an electric melting furnace, a steelmaking electric arc furnace, an argon blowing wire feeding station and an LF refining furnace, wherein the production process comprises the following steps:
s1, feeding direct reduced iron into an electric melting furnace for melting: the shaft furnace adopts low-grade ore to produce low-grade direct reduced iron, then adopts a high-temperature chain plate machine to send heat into an electric melting furnace, the temperature of the heat direct reduced iron entering the furnace is about 500 ℃, the total iron content of the direct reduced iron is 76.23%, the metallic iron is 70.9%, the metallization rate is 93%, the FeO content is 6.86%, and the SiO content is high 2 Content of 12.55%, al 2 O 3 The content of the direct reduced iron is 4.88 percent, the content of the C is 1 percent, and the direct reduced iron is melted in an electric melting furnace. The design capacity of the electric melting furnace is 50 ten thousand tons/year, the capacity of a transformer is 54MW, a slag former is added in the melting process, the alkalinity of slag is controlled to be 1.0-1.3, the temperature in the electric melting furnace is about 1550 ℃, the smelting electricity consumption is 560kwh/t of molten steel, and the nitrogen consumption is 350Nm 3 And/h. The electric melting furnace is continuously fed, a plurality of iron outlets and slag outlets are continuously tapped, the tapping cycle of a single iron outlet slag outlet is 4 hours, the tapping amount is 160t each time, the tapping cycle is 8 hours, and the tapping amount is 20.8t each time.
S2, smelting primary steelmaking water: adding molten iron in the step S1 into an electric arc furnace, supplying oxygen into the furnace through a carbon-oxygen gun on the furnace wall of the electric arc furnace, and simultaneously adding slag-forming materials into the furnace to perform decarburization, dephosphorization and heating operation, wherein the decarburization is performed until the endpoint C of the converter is 0.03-0.05%, P is less than or equal to 0.01%, and tapping can be performed at the temperature of 1650 ℃;
s3, refining and adjusting outside the furnace: and (2) carrying out primary adjustment on components of molten steel in the step (S2) through an online argon blowing wire feeding station, then carrying out fine adjustment on components and temperature through an LF refining furnace, and delivering the molten steel to a continuous casting machine for casting after meeting the requirements of continuous casting components and superheat degree, wherein the refining end point C is less than or equal to 30ppm, N is less than or equal to 30ppm, P is less than or equal to 0.01%, S is less than or equal to 0.01%, and the temperature is 1590 ℃.
Example 2
As shown in fig. 1, a low-carbon steelmaking process and equipment adopting low-grade direct reduced iron raw materials, comprising a high-temperature chain plate machine, an electric melting furnace, a steelmaking converter, an argon blowing wire feeding station and an LF refining furnace, wherein the production process comprises the following steps:
s1, feeding direct reduced iron into an electric melting furnace for melting: the shaft furnace adopts low-grade ore to produce low-grade direct reduced iron, then adopts a high-temperature chain plate machine to send heat into an electric melting furnace, the temperature of the heat direct reduced iron entering the furnace is about 500 ℃, the total iron content of the direct reduced iron is 76.23%, the metallic iron is 70.9%, the metallization rate is 93%, the FeO content is 6.86%, and the SiO content is high 2 Content of 12.55%, al 2 O 3 The content of the direct reduced iron is 4.88 percent, the content of the C is 1 percent, and the direct reduced iron is melted in an electric melting furnace. The design capacity of the electric melting furnace is 50 ten thousand tons/year, the capacity of a transformer is 54MW, a slag former is added in the melting process, the alkalinity of slag is controlled to be 1.0-1.3, the temperature in the electric melting furnace is about 1550 ℃, the smelting electricity consumption is 560kwh/t of molten steel, and the nitrogen consumption is 350Nm 3 And/h. The electric melting furnace is continuously fed, a plurality of iron outlets and slag outlets are continuously tapped, the tapping cycle of a single iron outlet slag outlet is 4 hours, the tapping amount is 160t each time, the tapping cycle is 8 hours, and the tapping amount is 20.8t each time.
S2, smelting primary steelmaking water: adding molten iron in the step S1 into a converter, supplying oxygen into the converter through an oxygen gun, and simultaneously adding slag forming materials into the converter to perform decarburization and dephosphorization operation, and supplementing heat into the converter through the reaction of adding a carburant and oxygen, wherein the feeding amount of the carburant is about 20kg/t of steel; decarburization is carried out until the endpoint C of the converter is 0.03-0.05%, P is less than or equal to 0.01%, and tapping can be carried out at the temperature of 1650 ℃.
S3, refining and adjusting outside the furnace: and (2) carrying out primary adjustment on components of molten steel in the step (S2) through an online argon blowing wire feeding station, then carrying out fine adjustment on components and temperature through an LF refining furnace, and delivering the molten steel to a continuous casting machine for casting after meeting the requirements of continuous casting components and superheat degree, wherein the refining end point C is less than or equal to 30ppm, N is less than or equal to 30ppm, P is less than or equal to 0.01%, S is less than or equal to 0.01%, and the temperature is 1590 ℃.
Comparative example 1
The process flow of the method takes common blast furnace molten iron as a raw material and comprises a blast furnace-converter-argon blowing wire feeding station-LF refining furnace. The converter is smelted by taking molten iron as a main raw material, wherein the end point C of the converter is 0.03-0.05%, P is less than or equal to 0.01%, the temperature is 1670 ℃, the content of N in molten steel is below 20ppm, at this time, tapping can be carried out after being treated by an online argon blowing wire feeding station until LF refining is carried out, the refining end point C is less than or equal to 30ppm, N is less than or equal to 30ppm, P is less than or equal to 0.01%, S is less than or equal to 0.01%, and qualified molten steel is obtained after tapping at the S temperature of 1590 ℃.
Comparative example 2
The process flow of the method is that the scrap steel and the high-grade metallized pellets are used as raw materials, and the process flow is that the scrap steel and the high-grade metallized pellets are used as an electric furnace and an LF refining furnace. And adding scrap steel and metallized pellets into an electric furnace for smelting operation. The smelting end point C of the electric furnace is more than or equal to 0.05%, P is less than or equal to 0.015%, tapping is carried out at 1690 ℃, the nitrogen content in the molten steel is about 80ppm, tapping is carried out at the moment and is lifted to an LF refining device, the LF refining end point C is less than or equal to 50ppm, N is less than or equal to 50ppm, and tapping is carried out at 1590 ℃ to obtain qualified molten steel.
Wherein the process for preparing the qualified molten steel in the example 1 has low carbon emission, adopts the natural gas reduction, the electric melting furnace and the electric arc furnace process, and has the total carbon emission of about 1.2t Carbon (C) /t Steel and method for producing same . By adopting the hydrogen reduction, green electric melting furnace and green electric arc furnace process, the total carbon emission is 0.4t Carbon (C) /t Steel and method for producing same 。
The process for producing a satisfactory molten steel in example 2, which has a low carbon emission, uses a natural gas reduction + electric melting furnace + converter process, and has a total carbon emission of about 1.1t Carbon (C) /t Steel and method for producing same . By adopting the hydrogen reduction, green electric melting furnace and green electric arc furnace process, the total carbon emission is 0.3t Carbon (C) /t Steel and method for producing same 。
Comparative example 1 Process for producing acceptable molten Steel, converter Using blast furnace molten iron as raw Material, the carbon emissions of the Process were high, and the carbon emissions of the whole Process were 2.0 to 2.2t Carbon (C) /t Steel and method for producing same 。
Comparative example 2 Process for producing acceptable molten steel, electric furnace using scrap steel and high grade metallized pellets as raw materials, the process did not use blast furnace molten iron, and the carbon content was 0.5t Carbon (C) /t Steel and method for producing same 。
In the low-carbon steelmaking method adopting the low-grade direct reduced iron raw materials in the embodiment 1 and the embodiment 2, the low-grade direct reduced iron raw materials are added into an electric melting furnace for melting, molten iron obtained by melting is added into an electric arc furnace or a converter, oxygen is supplied into the furnace through an oxygen lance, slag forming materials are added into the furnace at the same time for decarburization, dephosphorization, temperature rise and other operations, and tapping can be performed when the composition and the temperature of molten steel at the end point meet the tapping requirements. And then adding the molten steel into an external refining device for precise component and temperature adjustment to obtain qualified molten steel. The process method is used for smelting the direct reduced iron produced by the low-grade iron ore, does not adopt molten iron, and can effectively reduce the carbon emission of the steel production flow. In the future, if the blast furnace and the converter long-process steel mill are phased out, the process flow of the embodiment 2 can be adopted, and the converter and the refining facilities of the old long-process steel mill can be utilized, so that the equipment investment is reduced. The production process flow provides a reliable production path for low-carbon steelmaking in the future, has high popularization and can be suitable for large-scale production.
The carbon emission content of comparative example 2 is low, but the requirements on raw materials are scrap steel and high-grade metallized pellets, and the process of comparative example 2 has certain limitation under the conditions of insufficient global high-grade ore reserves and higher price of scrap steel (the price of scrap steel is 500-1000 yuan/t higher than that of direct reduced iron).
Finally, it is noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the present invention, which is intended to be covered by the claims of the present invention.
Claims (10)
1. A low-carbon steelmaking method taking low-grade direct reduced iron as a raw material is characterized in that: the method comprises the following steps:
s1, obtaining a direct reduced iron raw material from a hydrogen-based shaft furnace;
s2, loading the direct reduced iron raw material into an electric melting furnace through hot feeding or cold feeding;
s3, electrifying and heating in the electric melting furnace, adding a slag former, creating a reducing atmosphere to directly reduce iron, reducing and melting, and separating liquid molten iron and liquid slag;
s4, transferring the liquid molten iron into an arc furnace or a converter for converting into primary molten steel, and directly casting the primary molten steel on a continuous casting machine according to the steel type requirement or refining the primary molten steel by a refining device and then casting the primary molten steel on the continuous casting machine, wherein molten iron slag and steel slag are both transported to a slag treatment plant for treatment.
2. The low-carbon steelmaking process as claimed in claim 1, wherein the low-grade direct reduced iron is selected from the group consisting of: in the step S1, the ore for producing the direct reduced iron is middle and low grade iron ore with the T.Fe less than or equal to 65 percent.
3. The low-carbon steelmaking process as claimed in claim 1, wherein the low-grade direct reduced iron is selected from the group consisting of: the size of the direct reduced iron produced in step S1 is not limited.
4. The low-carbon steelmaking process as claimed in claim 1, wherein the low-grade direct reduced iron is selected from the group consisting of: in the step S3, slag formers are added in a multipoint distribution mode at the edge of the furnace wall of the electric melting furnace, a cold area is formed at the edge, and the smelting operation of wall-mounted slag and submerged arc smelting of the furnace and large slag quantity is realized.
5. The low-carbon steelmaking process as claimed in claim 1, wherein the low-grade direct reduced iron is selected from the group consisting of: in step S3, the power density in the hearth of the electric melting furnace<0.5MVA/m 2 。
6. The low-carbon steelmaking process as claimed in claim 1, wherein the low-grade direct reduced iron is selected from the group consisting of: the temperature of the electric melting furnace is controlled to 1450-1600 ℃.
7. The low-carbon steelmaking process as claimed in claim 1, wherein the low-grade direct reduced iron is selected from the group consisting of: in the step S4, when the liquid molten iron is smelted and tapped by the converter, the heat is insufficient, the carburant is added to supplement heat, and when the liquid molten iron is smelted and tapped by the electric arc furnace, the heat is insufficient, and the temperature is raised and supplemented by electrifying.
8. The low-carbon steelmaking process as claimed in claim 1, wherein the low-grade direct reduced iron is selected from the group consisting of: in the step S2, the transportation mode of the hot direct reduced iron is a pneumatic conveying device, a closed charging bucket or a high-temperature chain plate machine, and the transportation mode of the cold direct reduced iron or HBI is an automobile or a belt conveyor.
9. A low-carbon steelmaking system taking low-grade direct reduced iron as a raw material is characterized in that: the continuous casting device comprises a hydrogen-based shaft furnace, an electric melting furnace, an electric arc furnace or a converter and a continuous casting machine, wherein the hydrogen-based shaft furnace, the electric melting furnace, the electric arc furnace or the converter and the continuous casting machine are sequentially arranged along the material flow direction, the hydrogen-based shaft furnace is used for producing direct reduced iron, the electric melting furnace is used for melting the direct reduced iron to separate liquid molten iron and liquid slag, the electric arc furnace or the converter is used for smelting the liquid molten iron into molten steel, and the continuous casting machine is used for casting the molten steel.
10. A low carbon steelmaking system based on low grade direct reduced iron as defined in claim 9 wherein: a refining device is arranged between the electric arc furnace or the converter and the continuous casting machine, and the refining device is any one or more of an argon blowing wire feeding station, an LF or a RH, VD, VOD.
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