WO2022163202A1 - 転炉製鋼方法 - Google Patents
転炉製鋼方法 Download PDFInfo
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- WO2022163202A1 WO2022163202A1 PCT/JP2021/046722 JP2021046722W WO2022163202A1 WO 2022163202 A1 WO2022163202 A1 WO 2022163202A1 JP 2021046722 W JP2021046722 W JP 2021046722W WO 2022163202 A1 WO2022163202 A1 WO 2022163202A1
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- WIPO (PCT)
- Prior art keywords
- converter
- dephosphorization
- furnace
- iron source
- cold iron
- Prior art date
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- 238000000034 method Methods 0.000 title claims abstract description 47
- 238000009628 steelmaking Methods 0.000 title claims abstract description 23
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 426
- 229910052742 iron Inorganic materials 0.000 claims abstract description 213
- 238000011282 treatment Methods 0.000 claims abstract description 77
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 9
- 239000010959 steel Substances 0.000 claims abstract description 9
- 238000005261 decarburization Methods 0.000 claims description 40
- 239000002184 metal Substances 0.000 claims description 39
- 229910052751 metal Inorganic materials 0.000 claims description 39
- 238000007664 blowing Methods 0.000 claims description 25
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 16
- 229910052799 carbon Inorganic materials 0.000 claims description 14
- 238000002347 injection Methods 0.000 claims description 7
- 239000007924 injection Substances 0.000 claims description 7
- 230000001590 oxidative effect Effects 0.000 claims description 5
- 239000002994 raw material Substances 0.000 claims description 3
- 230000006866 deterioration Effects 0.000 abstract description 6
- 238000007670 refining Methods 0.000 abstract description 5
- 230000000717 retained effect Effects 0.000 abstract 2
- 238000003756 stirring Methods 0.000 description 11
- 239000007789 gas Substances 0.000 description 10
- 238000004090 dissolution Methods 0.000 description 8
- 238000012546 transfer Methods 0.000 description 8
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 6
- 229910001882 dioxygen Inorganic materials 0.000 description 6
- 238000002844 melting Methods 0.000 description 6
- 230000008018 melting Effects 0.000 description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 5
- 229910052710 silicon Inorganic materials 0.000 description 5
- 239000010703 silicon Substances 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 239000011261 inert gas Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 3
- 238000002485 combustion reaction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000155 melt Substances 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 239000004131 EU approved raising agent Substances 0.000 description 2
- 229910000519 Ferrosilicon Inorganic materials 0.000 description 2
- 229910000805 Pig iron Inorganic materials 0.000 description 2
- 238000013019 agitation Methods 0.000 description 2
- 239000000571 coke Substances 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000012886 linear function Methods 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000010079 rubber tapping Methods 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
Images
Classifications
-
- 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
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/36—Processes yielding slags of special composition
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/068—Decarburising
-
- 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
- C21C7/072—Treatment with gases
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D3/00—Charging; Discharging; Manipulation of charge
- F27D3/16—Introducing a fluid jet or current into the charge
-
- 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
- C21C2300/00—Process aspects
- C21C2300/08—Particular sequence of the process steps
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D3/00—Charging; Discharging; Manipulation of charge
- F27D3/16—Introducing a fluid jet or current into the charge
- F27D2003/162—Introducing a fluid jet or current into the charge the fluid being an oxidant or a fuel
- F27D2003/163—Introducing a fluid jet or current into the charge the fluid being an oxidant or a fuel the fluid being an oxidant
-
- 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
Definitions
- the present invention relates to a converter steelmaking method that increases the amount of cold iron source used while preventing unmelted cold iron source in the refining process of molten iron housed in a converter type vessel.
- the reaction heat of carbon and silicon contained as impurity elements in the hot metal compensates for the heat absorption due to the dissolution of the cold iron source. Carbon content and silicon content alone are insufficient for the amount of heat.
- the change in molten iron temperature during the treatment, especially in the first half of the treatment is also important.
- the heat of the surrounding molten iron is taken away due to the temperature rise of the cold iron source, and the temperature of the molten iron drops rapidly. If the amount of cold iron source used increases, the drop in the initial molten iron temperature will increase, making it difficult for the cold iron source to melt.
- a huge cold iron source mass hereafter, “iceberg”
- Patent Document 1 discloses a heat compensation method in which a heating agent such as ferrosilicon, graphite, or coke is supplied into the furnace and oxygen gas is supplied. techniques have been proposed.
- Patent Document 2 proposes a technique for promoting the melting of the cold iron source by promoting the stirring of the molten iron in the converter by supplying bottom-blown gas. This promotes heat transfer and mass transfer of carbon between the hot metal and the cold iron source by intensifying stirring (lowering of the melting point of the cold iron source due to carburization from the molten iron to the surface layer of the cold iron source).
- Patent Document 3 in performing dephosphorization treatment of hot metal using a converter-type furnace having a top-bottom blowing function, all or part of the cold iron source is poured from the furnace above the molten iron in the first half of the blowing.
- Patent Document 1 prolongs the processing time in the converter due to the supply of oxygen gas necessary for the oxidative combustion of carbon and silicon, resulting in a decrease in productivity.
- ferrosilicon is used, the amount of slag generated increases due to the generation of SiO 2 due to the combustion of silicon, and if graphite or coke is used, the amount of CO 2 gas generated increases due to the combustion of carbon.
- the enhanced bottom-blowing agitation described in Patent Document 2 is less effective than heat compensation.
- the cold iron source dissolution rate can be expressed as a linear function of the interfacial heat transfer coefficient or molten iron mass transfer coefficient.
- the heat transfer coefficient of the interface or the mass transfer coefficient of molten iron is proportional to the stirring energy to the power of 0.2 to 0.3. Therefore, even if the stirring power energy is increased by 1.5 times, the dissolution rate is increased by about 10%.
- the present invention has been made in view of the above circumstances, and in refining treatment of a cold iron source and hot metal contained in a converter type vessel, the cold iron source is prevented from remaining undissolved.
- the purpose of the present invention is to propose a converter steelmaking method that increases the amount of used and does not impair productivity.
- the converter steelmaking method of the present invention which advantageously solves the above problems, An auxiliary raw material is added to the cold iron source and the molten iron before dephosphorization contained in a converter-type vessel, and an oxidizing gas is supplied to dephosphorize the molten iron before dephosphorization, thereby producing molten iron after dephosphorization.
- a step of pouring the obtained molten iron after dephosphorization into a receiving container and holding it in the receiving container; or a second converter-type vessel different from the first converter-type vessel, and supplying an oxidizing gas to perform decarburization to obtain molten steel; has
- the first cold iron source is charged into the first converter-type vessel in an amount that satisfies the following formula (1), and then the hot metal before dephosphorization is charged.
- the dephosphorization treatment is performed, and the decarburization treatment is performed in the first converter-type vessel subjected to the dephosphorization treatment, or in the second converter-type vessel different from the first converter-type vessel.
- a second cold iron source is collectively charged, and then the dephosphorized molten iron held in the receiving vessel is charged to perform the decarburization treatment; % W s0 ⁇ 0.1186T-134 (% W s0 ⁇ 0) (1)
- % W s0 the ratio (%) of the first cold iron source charging amount to the sum of the first cold iron source charging amount and the hot metal charging amount before dephosphorization
- T Temperature of hot metal before dephosphorization (°C).
- the converter steelmaking method according to the present invention is 1. During one or both of the dephosphorization treatment and the decarburization treatment, a third cold iron source is introduced into the converter furnace vessel from above the furnace of the converter furnace vessel. thing, 2. During one or both of the dephosphorization treatment and the decarburization treatment, the third cold iron source introduced into the converter-type vessel from above the furnace of the converter-type vessel.
- W sadd amount of cold iron source input (t)
- t add Time (minutes) from the start of blowing to the start of the first injection at the time of the first furnace injection
- t add Time (minutes) from the start of blowing to the start of the first injection at the time of the first furnace injection
- the longest dimension of the third cold iron source introduced from above the furnace of the converter type vessel is 100 mm, 4.
- the carbon concentration contained in the third cold iron source is satisfying either one or both of 0.3% by mass or more and the temperature of the dephosphorized molten iron after completion of the dephosphorization treatment being 1380° C. or higher; etc. is considered to be a more preferable solution.
- dephosphorization is performed by setting an upper limit on the amount of cold iron source charged before the start of dephosphorization, and the obtained molten iron after dephosphorization is placed in a converter.
- the cold iron source is collectively charged before charging molten iron after dephosphorization, and decarburization is performed. This suppresses the drop in molten iron temperature at the initial stage of the dephosphorization treatment, suppressing the stagnation of cold iron source dissolution and the formation of icebergs. As a result, it is possible to increase the amount of the cold iron source used in the series of dephosphorization treatment or decarburization treatment while preventing the undissolved cold iron source.
- part of the cold iron source added during dephosphorization and decarburization is added from the top of the converter during processing.
- the maximum dimension of the cold iron source to be fed from the furnace to a size of 100 mm, problems with transportation equipment such as the furnace hopper and conveyor are avoided, and the cold iron source supply from the furnace is stabilized. It is possible to make
- FIG. 1(a) to 1(g) are diagrams for explaining one embodiment of a converter steelmaking method according to the present invention.
- FIG. 4(a) to 4(g) are diagrams for explaining another embodiment of the converter steelmaking method according to the present invention.
- FIGS. 1(a) to 1(g) are diagrams for explaining one embodiment of the converter steelmaking method according to the present invention. An embodiment of the converter steelmaking method of the present invention will be described below with reference to FIGS. 1(a) to 1(g).
- first converter-type vessel 1 having a top and bottom blowing function
- iron scrap as a first cold iron source 3 is fed from a scrap chute 2 to a second It is charged into one converter type vessel 1 (Fig. 1(a)).
- hot metal 5 hereinafter also referred to as pre-dephosphorization hot metal 5
- oxygen gas is supplied from the top-blowing lance 6, and an inert gas such as N2 is supplied as a stirring gas from the bottom-blowing tuyeres 7 installed at the bottom of the furnace.
- the molten iron 8 in the first converter-type vessel 1 is dephosphorized while the auxiliary materials are being added to obtain the molten iron 9 after dephosphorization (FIG. 1(c)). After that, the obtained molten iron 9 after dephosphorization is discharged into the receiving container 10 and held in the receiving container 10 (FIG. 1(d)).
- a second cold iron source 12 is collectively charged into a second converter-type vessel 11 different from the first converter-type vessel 1 (FIG. 1(e)).
- the dephosphorized molten iron 9 held in the hot water receiving container 10 is charged into the second converter type container 11 (FIG. 1(f)).
- the first converter-type vessel 1 subjected to the dephosphorization treatment can be used.
- oxygen gas is supplied from the top-blowing lance 6, and an inert gas such as N2 is supplied as a stirring gas from the bottom-blowing tuyeres 7 installed at the bottom of the furnace, and heat-raising agents, slag-forming agents and the like are supplied.
- decarburization treatment is performed on the dephosphorized molten iron 9 in the second converter-type vessel 11 (FIG. 1(g)).
- the amount of the cold iron source to be charged before the dephosphorization treatment and before the decarburization treatment is determined by setting the total amount of the amount to be charged before both the above treatments (total planned cold iron source charging amount).
- the charging amount of the second cold iron source 12 may be determined as an amount corresponding to the difference between the planned charging amount of all the cold iron sources and the amount of the first cold iron source 3 .
- the charging amount of the first cold iron source 3 charged during the dephosphorization process is set to an amount that satisfies the following formula (1). It is possible to suppress the decline and suppress cold iron source dissolution stagnation and iceberg formation: % W s0 ⁇ 0.1186T-134 (% W s0 ⁇ 0) (1)
- % W s0 the ratio (%) of the first cold iron source charging amount to the sum of the first cold iron source charging amount and the hot metal charging amount before dephosphorization
- T Temperature of hot metal before dephosphorization (°C).
- the charging amount of the second cold iron source 12 charged during the decarburization process may exceed the upper limit amount obtained from the formula (1). This is because the temperature of the molten metal is higher in the decarburization treatment than in the dephosphorization treatment, so even if the second cold iron source 12 is charged in a large amount, it is difficult to leave unmelted molten metal.
- FIGS. 2(a) to 2(g) are diagrams for explaining another embodiment of the converter steelmaking method according to the present invention.
- FIGS. 2(a) to 2(g) are diagrams for explaining another embodiment of the converter steelmaking method according to the present invention.
- another embodiment of the converter steelmaking method of the present invention will be described with reference to FIGS. 2(a) to 2(g).
- molten iron 8 in the first converter-type vessel 1 is dephosphorized while the auxiliary materials are being added to obtain the molten iron 9 after dephosphorization (FIG. 2(c)).
- the entire amount of the cold iron source used during the dephosphorization treatment is used as the first cold iron source 3 before the dephosphorization treatment at the stage of FIG.
- part of the cold iron source used during dephosphorization is transferred from the scrap chute 2 to the first transfer as the first cold iron source 3 before the dephosphorization treatment.
- the remaining cold iron source 14 is charged into the furnace type vessel 1 and the remaining cold iron source 14 is charged into the first converter type vessel 1 from above the furnace via the furnace top hopper 13 as the third cold iron source 14 (C-1, C-3) and one of the steps are performed.
- the obtained molten iron 9 after dephosphorization is poured into the receiving container 10 and held in the receiving container 10 (Fig. 2(d)).
- the second cold iron source 12 is collectively charged into a second converter-type vessel 11 different from the first converter-type vessel 1 (Fig. 2(e)).
- the dephosphorized molten iron 9 held in the hot water receiving container 10 is charged into the second converter type container 11 (FIG. 2(f)).
- the first converter-type vessel 1 subjected to the dephosphorization treatment can be used.
- the amount of cold iron source used before dephosphorization treatment or during decarburization treatment is the total amount of the amount used in the above two treatments (total cold iron source planned amount used), and the second cold iron source
- the charging amount of the source 12 may be determined as an amount corresponding to the difference between the planned use amount of the entire cold iron source and the amount of the first cold iron source 3 .
- part of the cold iron source used for decarburization is charged as the second cold iron source 12 from the scrap chute 2 into the second converter type vessel 12, while the remaining cold iron source 14 is placed in the furnace.
- the second converter type vessel 12 from above the furnace via the upper hopper 13 (G-2, G-3), either step is performed.
- step G-2 step G-2 is performed, step G-2 is performed, and when step C-3 is performed, step G-3 is performed.
- the cold iron source is introduced into the converter furnace vessel from above the furnace of the converter furnace vessel.
- the furnace hopper 13 When the cold iron source 14 is added once or in multiple times from the furnace hopper, the amount of cold iron source added at one time from the furnace hopper is the following (2) in order to minimize the temperature drop of the molten iron.
- W sadd amount of cold iron source input (t)
- t add Time from the start of blowing to the start of the first injection (minutes) when the first furnace injection is performed For the second and subsequent feeding, the time (minutes) from the completion of the previous feeding to the start of the next feeding.
- the timing of adding the cold iron source should be adjusted when the cold iron source already added in the furnace melts and the molten iron temperature rises. By adjusting the timing, it is possible to efficiently melt the cold iron source while suppressing the stagnation of the cold iron source dissolution and the generation of icebergs.
- the cold iron source 14 to be put into the upper hopper 13 is cut to a size of 100 mm or less in the longest dimension (inner dimensions of 100 mm ⁇ 100 mm ⁇ 100 mm) by cutting, etc., in consideration of handling in the hopper 13 on the furnace and conveying equipment such as a conveyor. size that fits in the box).
- the first cold iron source 3 charged from the scrap chute melts as the dephosphorization treatment progresses, and at the timing when the molten iron temperature rises, the third cold iron source 14 is charged from the furnace. do.
- the carbon concentration contained in the third cold iron source 14 charged from the furnace is 0.3% by mass or more, and the temperature of the dephosphorized molten pig iron after completion of the dephosphorization treatment is 1380° C. or higher, or both. By doing so, it is possible to suppress the unmelted residue of the third cold iron source 14 that has been put into the furnace.
- the second cold iron source 12 charged from the scrap chute melts as the decarburization process progresses, and at the timing when the molten iron temperature rises, the third cold iron source 14 is charged from the furnace. .
- hot metal is not limited to hot metal tapped from a blast furnace.
- the present invention is equally applicable to molten iron obtained from a cupola, induction melting furnace, arc furnace, etc., or to molten iron obtained by mixing these molten iron with molten iron tapped from a blast furnace.
- Example 1 The amount of cold iron source in the dephosphorization process was investigated. Hot metal tapped from a blast furnace and a cold iron source (scrap) were used to perform hot metal dephosphorization treatment in a top-bottom blown converter (first converter-type vessel). The hot metal temperature and hot metal phosphorus concentration before dephosphorization were 1230 to 1263° C. and 0.130 to 0.134%, respectively. The amount of molten iron charged before dephosphorization and the amount of scrap charged from the scrap chute were variously changed, and the temperature of the molten iron after dephosphorization was controlled at 1350°C. In this hot metal dephosphorization treatment, a cold iron source was not introduced from above the furnace. Table 1 shows the results.
- the amount of scrap charged from the scrap chute is the level exceeding the upper limit amount obtained from the above formula (1), that is, the total charged amount (the amount of molten iron before dephosphorization + from the scrap chute At a level (Test Nos. 4 to 6) where the ratio of scrap amount to 0.1186T-134 (T: hot metal temperature before dephosphorization, ° C.), unmelted scrap occurred.
- T hot metal temperature before dephosphorization, ° C.
- Example 2 For the molten iron after the dephosphorization treatment in Example 1, the divided introduction of the cold iron source (scrap) in the decarburization treatment was investigated.
- the ratio of the amount of scrap to the total amount charged (amount of hot metal before dephosphorization + amount of scrap charged from the scrap chute) was calculated by the above formula (1).
- the scrap was also used in a top-bottom blown converter (second converter-type vessel) that performs decarburization treatment after setting it to the upper limit value or less obtained from .
- the scrap was divided into the second converter type vessel (decarburization furnace).
- scrap was charged from a scrap chute before molten iron was charged, and then scrap was added from above the furnace during decarburization. There was no unmelted residue in the dephosphorization furnace, and the molten iron temperature before decarburization treatment in the decarburization furnace was 1,360 to 1,380°C, and the molten steel temperature after decarburization treatment was 1,640 to 1,650°C. Table 2 shows the results.
- the amount of scrap used can be stably increased by dividing the amount of scrap added at one time from the furnace hopper in the decarburizing furnace to the upper limit value obtained from the above formula (2) or less. was confirmed to be possible.
- the addition of scrap from the furnace was found to have the same effect not only in the decarburization process but also in the dephosphorization process.
- Example 3 the size of scrap charged from above the furnace was investigated.
- Test No. 1 in Table 3 was found.
- 21 to 23 by setting the scrap size to a size with the longest dimension of 100 mm or less (a size that fits in a box with an inner dimension of 100 mm ⁇ 100 mm ⁇ 100 mm), troubles in the conveying system such as conveyors do not occur, and the scrap is stable. It was found that it is possible to put it on the furnace by
- Example 4 Injection of scrap into the furnace in the second half of the dephosphorization process was investigated.
- the amount of scrap charged from the scrap chute (the amount of pre-charged scrap) was made equal to or less than the upper limit value obtained from the formula (1), and the scrap was charged into the furnace only once after the start of treatment.
- the hot metal temperature before dephosphorization is 1250 to 1260° C.
- the upper limit of the pre-charged scrap amount obtained from the formula (1) is 14.5 to 15.6%.
- the timing of throwing the scrap into the furnace was set at 65 to 75% of the progress of blowing. Table 4 shows the results.
- the hot metal tapped from the blast furnace and the cold iron source (scrap) were used for the treatment, but the hot metal is not limited to the hot metal tapped from the blast furnace.
- the present invention is equally applicable to molten iron obtained from a cupola, induction melting furnace, arc furnace, etc., or to molten iron obtained by mixing these molten iron with molten iron tapped from a blast furnace.
- the converter steelmaking method of the present invention is industrially useful because it can be applied to any method as long as it is a method of obtaining molten steel by refining molten pig iron in a converter using a cold iron source. .
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- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
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Abstract
Description
転炉型容器内に収容された冷鉄源および脱燐前溶銑に対して、副原料を添加するとともに酸化性ガスを供給して該脱燐前溶銑の脱燐処理を行ない脱燐後溶鉄を得、得られた脱燐後溶鉄を受湯容器に出湯して受湯容器に保持するステップと、前記受湯容器に保持された前記脱燐後溶鉄を、前記脱燐処理を行なった第一の転炉型容器、または前記第一の転炉型容器とは別の第二の転炉型容器に再装入し、酸化性ガスを供給して脱炭処理を行ない、溶鋼を得るステップと、を有し、
前記脱燐処理は、前記第一の転炉型容器に、第一の冷鉄源を、以下の(1)式を満たす量だけ一括装入した後、前記脱燐前溶銑を装入して該脱燐処理を行ない、前記脱炭処理は、前記脱燐処理を行なった前記第一の転炉型容器、または前記第一の転炉型容器とは別の前記第二の転炉型容器に、第二の冷鉄源を一括装入した後、前記受湯容器に保持された前記脱燐後溶鉄を装入して該脱炭処理を行なう、転炉製鋼方法である:
%Ws0≦0.1186T-134 (%Ws0≧0) …(1)
ここで、%Ws0:第一の冷鉄源装入量と脱燐前溶銑装入量との和に対する第一の冷鉄源装入量の割合(%)
T:脱燐前溶銑の温度(℃)。
1.前記脱燐処理および前記脱炭処理のいずれかの処理、または両方の処理の処理中に、前記転炉型容器の炉上から該転炉型容器内に、第三の冷鉄源を投入すること、
2.前記脱燐処理および前記脱炭処理のいずれかの処理、または両方の処理の処理中に、前記転炉型容器の炉上から該転炉型容器内に投入する前記第三の冷鉄源を以下の(2)式を満たす量ずつ投入すること:
Wsadd≦2.4tadd …(2)
ここで、Wsadd:冷鉄源投入量(t)
tadd:1回目炉上投入時は、吹錬開始から1回目投入開始までの時間(分)
2回目以降投入時は、前回投入完了から次回投入開始までの時間(分)、
3,前記転炉型容器の炉上から投入される前記第三の冷鉄源の最長寸法が100mmであること、
4.前記脱燐処理中に前記転炉型容器の炉上から該転炉型容器内に前記第三の冷鉄源を装入する場合、該第三の冷鉄源に含有されている炭素濃度が0.3質量%以上であること、および前記脱燐処理終了後の脱燐後溶鉄の温度が1380℃以上であること、のいずれか一方または両方を満たすこと、
などがより好ましい解決手段になり得るものと考えられる。
図1(a)~(g)は、それぞれ、本発明にかかる転炉製鋼方法の一実施態様を説明するための図である。以下、図1(a)~(g)を参照して、本発明の転炉製鋼方法の一実施態様を説明する。
%Ws0≦0.1186T-134 (%Ws0≧0) …(1)
ここで、%Ws0:第一の冷鉄源装入量と脱燐前溶銑装入量との和に対する第一の冷鉄源装入量の割合(%)
T:脱燐前溶銑の温度(℃)。
図2(a)~(g)は、それぞれ、本発明にかかる転炉製鋼方法の他の実施態様を説明するための図である。以下、図2(a)~(g)を参照して、本発明の転炉製鋼方法の他の実施態様を説明する。
Wsadd≦2.4tadd …(2)
ここで、Wsadd:冷鉄源投入量(t)
tadd:1回目炉上投入時は 吹錬開始から1回目投入開始までの時間(分)
2回目以降投入時は 前回投入完了から次回投入開始までの時間(分)。
脱燐処理における冷鉄源の量について調べた。高炉から出銑された溶銑および、冷鉄源(スクラップ)を用い、上底吹き転炉(第一の転炉型容器)において溶銑脱燐処理を行った。脱燐処理前の溶銑温度および溶銑燐濃度はそれぞれ、1230~1263℃、0.130~0.134%であった。脱燐前溶銑の装入量およびスクラップシュートから装入するスクラップ量を種々変化させて処理を行い、脱燐処理後の溶鉄の温度は1350℃に制御した。なお、この溶銑脱燐処理においては、炉上からの冷鉄源投入は行わなかった。結果を表1に示す。
実施例1の脱燐処理後の溶鉄に対し、脱炭処理における冷鉄源(スクラップ)の分割投入について調べた。実施例1の第一の転炉型容器を用いた脱燐処理において全装入量(脱燐前溶銑量+スクラップシュートから装入されたスクラップ量)に対するスクラップ量の割合を前記(1)式から得られる上限値以下とした上で、脱炭処理を行う上底吹き転炉(第二の転炉型容器)でもスクラップを使用した。スクラップの使用による溶鉄温度の低下を最小限に抑え、効率的にスクラップを溶解するため、第二の転炉型容器(脱炭炉)ではスクラップの分割投入を行った。具体的には、溶鉄装入前にスクラップシュートからスクラップを装入した上で、脱炭処理中に炉上からのスクラップ添加を行った。なお、脱燐炉における溶け残りはなく、脱炭炉における脱炭処理前の溶鉄温度は1360~1380℃、脱炭処理後の溶鋼温度は1640~1650℃であった。結果を表2に示す。
実施例2で炉上から投入するスクラップ寸法について調べた。実施例2において、炉上から投入するスクラップ寸法を変化させたところ、以下の表3の試験No.21~23に示す通り、スクラップ寸法を、最長寸法が100mm以下のサイズ(内寸が100mm×100mm×100mmの箱に入るサイズ)とすることで、コンベア等の搬送系トラブルを起こさず、安定して炉上投入することが可能であることがわかった。
脱燐処理後半におけるスクラップの炉上投入について調べた。スクラップシュートから装入されるスクラップ量(前装入スクラップ量)を前記(1)式から得られる上限値以下とした上で、処理開始後に1回のみスクラップの炉上投入を行った。脱燐処理前の溶銑温度は1250~1260℃であり、前記(1)式から得られる前装入スクラップ量の上限値は14.5~15.6%となる。スクラップ炉上投入タイミングは吹錬進行度65~75%とした。結果を表4に示す。
2 スクラップシュート
3 第一の冷鉄源
4 装入鍋
5 (脱燐前)溶銑
6 上吹きランス
7 底吹き羽口
8 溶鉄
9 (脱燐後)溶鉄
10 受湯容器
11 第二の転炉型容器
12 第二の冷鉄源
13 炉上ホッパー
14 炉上添加冷鉄源
Claims (5)
- 転炉製鋼方法であって、
転炉型容器内に収容された冷鉄源および脱燐前溶銑に対して、副原料を添加するとともに酸化性ガスを供給して該脱燐前溶銑の脱燐処理を行ない脱燐後溶鉄を得、得られた脱燐後溶鉄を受湯容器に出湯して受湯容器に保持するステップと、
前記受湯容器に保持された前記脱燐後溶鉄を、前記脱燐処理を行なった第一の転炉型容器、または前記第一の転炉型容器とは別の第二の転炉型容器に再装入し、酸化性ガスを供給して脱炭処理を行ない、溶鋼を得るステップと、を有し、
前記脱燐処理は、前記第一の転炉型容器に、第一の冷鉄源を、以下の(1)式を満たす量だけ一括装入した後、前記脱燐前溶銑を装入して該脱燐処理を行ない、
前記脱炭処理は、前記脱燐処理を行なった前記第一の転炉型容器、または前記第一の転炉型容器とは別の前記第二の転炉型容器に、第二の冷鉄源を一括装入した後、前記受湯容器に保持された前記脱燐後溶鉄を装入して該脱炭処理を行なう、転炉製鋼方法:
%Ws0≦0.1186T-134 (%Ws0≧0) …(1)
ここで、%Ws0:第一の冷鉄源装入量と脱燐前溶銑装入量との和に対する第一の冷鉄源装入量の割合(%)
T:脱燐前溶銑の温度(℃)。 - 前記脱燐処理および前記脱炭処理のいずれかの処理、または両方の処理の処理中に、前記転炉型容器の炉上から該転炉型容器内に、第三の冷鉄源を投入する、請求項1に記載の転炉製鋼方法。
- 前記脱燐処理および前記脱炭処理のいずれかの処理、または両方の処理の処理中に、前記転炉型容器の炉上から該転炉型容器内に投入する前記第三の冷鉄源を以下の(2)式を満たす量ずつ投入する、請求項2に記載の転炉製鋼方法:
Wsadd≦2.4tadd …(2)
ここで、Wsadd:冷鉄源投入量(t)
tadd:1回目炉上投入時は、吹錬開始から1回目投入開始までの時間(分)
2回目以降投入時は、前回投入完了から次回投入開始までの時間(分)。 - 前記転炉型容器の炉上から投入される前記第三の冷鉄源の最長寸法が100mmである、請求項2または3に記載の転炉製鋼方法。
- 前記脱燐処理中に前記転炉型容器の炉上から該転炉型容器内に前記第三の冷鉄源を装入する場合、該第三の冷鉄源に含有されている炭素濃度が0.3質量%以上であること、および前記脱燐処理終了後の脱燐後溶鉄の温度が1380℃以上であること、のいずれか一方または両方を満たす、請求項2ないし4のいずれか1項に記載の転炉製鋼方法。
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