WO2022201562A1 - 銑鉄製造方法 - Google Patents
銑鉄製造方法 Download PDFInfo
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- WO2022201562A1 WO2022201562A1 PCT/JP2021/017701 JP2021017701W WO2022201562A1 WO 2022201562 A1 WO2022201562 A1 WO 2022201562A1 JP 2021017701 W JP2021017701 W JP 2021017701W WO 2022201562 A1 WO2022201562 A1 WO 2022201562A1
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- Prior art keywords
- iron
- raw material
- ore
- reduced iron
- layer
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- 229910000805 Pig iron Inorganic materials 0.000 title claims abstract description 43
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 35
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 255
- 229910052742 iron Inorganic materials 0.000 claims abstract description 81
- 239000002994 raw material Substances 0.000 claims abstract description 81
- 239000008188 pellet Substances 0.000 claims abstract description 60
- 239000000571 coke Substances 0.000 claims abstract description 41
- 238000002844 melting Methods 0.000 claims abstract description 23
- 230000008018 melting Effects 0.000 claims abstract description 22
- 239000000446 fuel Substances 0.000 claims abstract description 11
- 230000001603 reducing effect Effects 0.000 claims abstract description 11
- 238000007664 blowing Methods 0.000 claims abstract description 6
- 238000000748 compression moulding Methods 0.000 claims abstract description 4
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 14
- 239000002075 main ingredient Substances 0.000 abstract 1
- 230000035699 permeability Effects 0.000 description 29
- 230000009467 reduction Effects 0.000 description 28
- 239000002245 particle Substances 0.000 description 21
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 18
- 239000011148 porous material Substances 0.000 description 15
- 238000000034 method Methods 0.000 description 12
- 239000000843 powder Substances 0.000 description 10
- 239000002893 slag Substances 0.000 description 10
- 239000007789 gas Substances 0.000 description 9
- 239000000377 silicon dioxide Substances 0.000 description 9
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 8
- 229910052681 coesite Inorganic materials 0.000 description 8
- 229910052906 cristobalite Inorganic materials 0.000 description 8
- 230000000694 effects Effects 0.000 description 8
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 8
- 235000012239 silicon dioxide Nutrition 0.000 description 8
- 229910052682 stishovite Inorganic materials 0.000 description 8
- 229910052905 tridymite Inorganic materials 0.000 description 8
- 238000004090 dissolution Methods 0.000 description 7
- 239000003795 chemical substances by application Substances 0.000 description 6
- 238000003475 lamination Methods 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 239000003638 chemical reducing agent Substances 0.000 description 5
- 239000003245 coal Substances 0.000 description 5
- 238000009826 distribution Methods 0.000 description 5
- 238000011017 operating method Methods 0.000 description 5
- 125000006850 spacer group Chemical group 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 230000001737 promoting effect Effects 0.000 description 4
- 239000000378 calcium silicate Substances 0.000 description 3
- 229910052918 calcium silicate Inorganic materials 0.000 description 3
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 3
- 238000005255 carburizing Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 239000010439 graphite Substances 0.000 description 3
- 229910002804 graphite Inorganic materials 0.000 description 3
- 238000010298 pulverizing process Methods 0.000 description 3
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 238000001465 metallisation Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 238000009423 ventilation Methods 0.000 description 2
- 239000004484 Briquette Substances 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 229910001018 Cast iron Inorganic materials 0.000 description 1
- 235000019738 Limestone Nutrition 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229910000514 dolomite Inorganic materials 0.000 description 1
- 239000010459 dolomite Substances 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000000295 fuel oil Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 238000010309 melting process Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 230000001846 repelling effect Effects 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000013076 target substance Substances 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B5/00—Making pig-iron in the blast furnace
- C21B5/008—Composition or distribution of the charge
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B5/00—Making pig-iron in the blast furnace
- C21B5/001—Injecting additional fuel or reducing agents
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B5/00—Making pig-iron in the blast furnace
- C21B5/007—Conditions of the cokes or characterised by the cokes used
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B9/00—Stoves for heating the blast in blast furnaces
- C21B9/10—Other details, e.g. blast mains
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/16—Sintering; Agglomerating
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/242—Binding; Briquetting ; Granulating with binders
- C22B1/243—Binding; Briquetting ; Granulating with binders inorganic
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/242—Binding; Briquetting ; Granulating with binders
- C22B1/244—Binding; Briquetting ; Granulating with binders organic
- C22B1/245—Binding; Briquetting ; Granulating with binders organic with carbonaceous material for the production of coked agglomerates
Definitions
- the present invention relates to a method for producing pig iron.
- a first layer containing ore raw material and a second layer containing coke are alternately laminated in a blast furnace, and the ore raw material is reduced and melted while blowing auxiliary fuel into the blast furnace with hot air blown from the tuyeres.
- the coke serves as a heat source for melting the ore raw material, a reducing agent for the ore raw material, a recarburizing agent for carburizing the molten iron to lower the melting point, and a spacer for ensuring air permeability in the blast furnace. play.
- the proportion of coke is low from the viewpoint of cost reduction.
- lowering the proportion of coke also reduces the above-mentioned role of coke.
- a blast furnace operating method has been proposed in which reduced iron having a small particle size is charged to the periphery of the blast furnace (see Japanese Patent Application Laid-Open No. 11-315308). ).
- reduced iron that does not need to be reduced is charged only in the peripheral portion of the furnace, thereby maintaining the role of coke as a heat source, reducing agent, recarburizing agent and spacer in the central portion of the furnace. It is said that it is possible to increase the filling rate of the raw material.
- the present invention has been made based on the circumstances described above, and aims to provide a method for producing pig iron that can reduce the amount of coke used while maintaining stable operation of the blast furnace.
- a method for producing pig iron according to an aspect of the present invention is a method for producing pig iron using a blast furnace having a tuyere, wherein a first layer containing an ore raw material and a second layer containing coke are placed in the blast furnace. and a step of reducing and melting the ore raw material of the stacked first layer while blowing auxiliary fuel into the blast furnace with hot air blown from the tuyeres, wherein reduced iron is mixed in the first layer, the ore raw material is iron ore pellets as a main raw material, and the average basicity of the reduced iron compact is 0.5 or less. and the average basicity of the iron ore pellets is 0.9 or more.
- the first layer containing the ore raw material contains a reduced iron compact obtained by compressing reduced iron as an aggregate.
- This reduced iron compact makes it easier for hot air to pass through when softening and fusing the first layer in the melting process.
- the reduced iron compact since the reduced iron compact having an average basicity of 0.5 or less is used, the reduced iron compact can be obtained at a relatively low cost.
- the pig iron production method by using iron ore pellets with an average basicity of 0.9 or more as the main raw material, the increase in viscosity when the reduced iron compact with low basicity melts is suppressed, promote This mainly improves the air permeability of the cohesive zone and further reduces the amount of coke used. Therefore, by using the pig iron production method, it is possible to reduce the amount of coke used while maintaining stable operation of the blast furnace.
- the content of the iron ore pellets in the ore raw material is preferably 50% by mass or more. By making the content of the iron ore pellets equal to or higher than the lower limit, the air permeability can be further improved.
- the iron ore pellets are self-fluxing. By making the iron ore pellets self-fluxing in this way, the burn-through of the reduced iron compact can be promoted, and the air permeability can be further improved.
- a ratio R of the basic unit of the iron ore pellets to the basic unit of the reduced iron compact preferably satisfies the following formula 1.
- the ratio R of the basic unit of the iron ore pellets to the basic unit of the reduced iron compact satisfies the following formula 1, so that the effect of improving the permeability due to the burn-through of the reduced iron compact can be more reliably expressed. be able to.
- (C/S) represents the average basicity
- (% SiO 2 ) represents the SiO 2 content [% by mass].
- the suffix HBI indicates a reduced iron compact
- P indicates an iron ore pellet.
- (C/S) critical represents the critical basicity of HBI.
- main raw material refers to a raw material having the largest content in terms of mass.
- Basis refers to the ratio of the mass of CaO to the mass of SiO2 .
- average basicity means the ratio of the total mass of CaO to the total mass of SiO 2 of the plurality of particles when the target substance is composed of a plurality of particles. do.
- “Critical basicity” is, as shown in Fig. 3, with the average basicity of HBI as a parameter, continuously measuring the pressure drop of the sample packed bed, and plotting the maximum value (maximum pressure drop), the maximum pressure drop decreases. It refers to the average basicity at which As shown in FIG. 5, for example, the sample-filled layer is formed by using a large load reduction experimental furnace 7 in which the inner diameter of the graphite crucible 71 filled with the sample is ⁇ 75 mm. , an ore layer 72b (110 mm high) and a lower coke layer 72c (40 mm high).
- FIG. 1 is a flowchart showing a pig iron production method according to one embodiment of the present invention.
- FIG. 2 is a schematic diagram showing the inside of a blast furnace used in the pig iron manufacturing method of FIG.
- FIG. 3 is a graph showing the relationship between the average basicity and maximum pressure loss of reduced iron compacts.
- FIG. 4 is a schematic partially enlarged view from the cohesive zone to the dropping zone in FIG.
- FIG. 5 is a schematic cross-sectional view showing the configuration of a large load reduction experimental furnace used in the examples.
- FIG. 6 is a graph showing the temperature profile for heating the sample packed bed in the example.
- FIG. 7 is a graph showing the relationship between the temperature of the sample packed bed and the flow rate of the supplied gas in the example.
- FIG. 8 is a graph showing the results of the example.
- the pig iron manufacturing method shown in FIG. 1 is a method for manufacturing pig iron using the blast furnace 1 shown in FIG. 2, and includes a stacking step S1 and a reduction melting step S2.
- the blast furnace 1 has, as shown in FIG. 2, a tuyere 1a provided in the lower part of the furnace and a taphole 1b. A plurality of tuyeres 1a are usually provided.
- the blast furnace 1 is a solid-air countercurrent type shaft furnace, and hot air obtained by adding high temperature or normal temperature oxygen to high temperature air is blown into the furnace from the tuyeres 1a to produce the ore raw material 11 described later. After a series of reactions such as reduction and melting, pig iron can be taken out from the tap hole 1b.
- the blast furnace 1 is equipped with a material charging device 2 of the Bell Armor type. This raw material charging device 2 will be described later.
- the first layers 10 and the second layers 20 are alternately stacked in the blast furnace 1, as shown in FIG. That is, the number of layers of the first layer 10 and the number of layers of the second layer 20 is two or more.
- the first layer 10 contains an ore raw material 11 .
- Aggregates 12 are mixed in the first layer 10 .
- auxiliary raw materials such as limestone, dolomite, silica stone, etc. may be charged together.
- the ore raw material 11 refers to ores that become iron raw materials.
- the ore raw material 11 is heated and reduced by hot air blown from the tuyere 1a in the reduction melting step S2 to become molten pig iron.
- iron ore pellets are used as the main raw material.
- "Iron ore pellets" are made from iron ore fine powder of several tens of micrometers, and are made by improving the properties (such as size, strength, reducibility, etc.) suitable for blast furnaces.
- the iron ore pellets preferably do not contain fine powder of sintered ore.
- the lower limit of the average basicity of the iron ore pellets is 0.9, more preferably 1.0, which is basic, and even more preferably 1.4. If the basicity of the iron ore pellets is less than the above lower limit, it may be difficult to promote burn-through of the reduced iron compact, and the air permeability may decrease.
- the upper limit of the average basicity of the iron ore pellets is not particularly limited, the average basicity of the iron ore pellets is usually 2.0 or less.
- the lower limit of the iron ore pellet content in the ore raw material 11 is preferably 50% by mass, more preferably 90% by mass, and more preferably 100% by mass, that is, the ore raw material 11 is all iron ore pellets.
- the iron ore pellets are self-fluxing. By making the iron ore pellets self-fluxing in this way, the burn-through of the reduced iron compact can be promoted, and the air permeability can be further improved.
- the iron ore pellet has a porosity of 21% or more for coarse open pores having a pore diameter of 4 ⁇ m or more.
- the reduction rate of the ore raw material can be increased. can be reduced.
- the “porosity of coarse open pores with a pore diameter of 4 ⁇ m or more” refers to the volume ratio of coarse open pores with a pore diameter of 4 ⁇ m or more to the apparent volume of the iron ore pellet.
- Open porosity ⁇ 0 [%] of iron ore pellets measured using a porosimeter (for example, “Autopore III 9400” manufactured by Shimadzu Corporation), total pore volume A [cm 3 /g] per unit weight of iron ore pellets , is the amount calculated by ⁇ 0 ⁇ A +4 /A [%], where A +4 [cm 3 /g] is the total pore volume with a pore diameter of 4 ⁇ m or more per unit weight of the iron ore pellet.
- the open pores refer to pores that are open to the outside of the iron ore pellet, and the closed pores refer to pores that are closed inside the iron ore pellet.
- the iron ore pellets preferably contain MgO.
- MgO has the effect of increasing the desulfurization ability of slag at the hearth level and increasing the reducibility at high temperatures. For this reason, it is considered that by making the behavior of the burn-through of the ore raw material 11 closer to that of the reduced iron compact, there is an effect of promoting the burn-through of the reduced iron compact.
- the lower limit of the MgO content in the ore raw material 11 is preferably 1% by mass, more preferably 1.5% by mass.
- the upper limit of the MgO content is preferably 4% by mass, more preferably 3% by mass.
- the content of MgO is less than the above lower limit, there is a possibility that the effect of promoting the burn-through of the reduced iron compact may not be sufficiently obtained. Conversely, if the MgO content exceeds the upper limit, the strength of the iron ore pellet may decrease.
- the ore raw material 11 may include sintered ore, lump ore, carbon material-containing agglomerate ore, metal, etc., in addition to the iron ore pellets.
- the content of the sintered ore in the ore raw material 11 is preferably 10% by mass or less, and more preferably 0% by mass, that is, the ore raw material 11 does not contain sintered ore.
- the reduced iron compacts contained in the aggregate 12 to be described later can also be the iron raw material, but the reduced iron compacts are not included in the ore raw material 11 in this specification.
- the aggregate 12 is for improving the air permeability of the cohesive zone D, which will be described later, and allowing the hot air to pass through to the center of the blast furnace 1.
- the aggregate 12 includes a reduced iron compact (HBI, Hot Briquette Iron) obtained by compression molding reduced iron.
- HBI is formed by molding direct reduced iron (DRI) in a hot state.
- DRI direct reduced iron
- HBI has a low porosity and is difficult to reoxidize.
- the aggregate 12 After ensuring the air permeability of the first layer 10, the aggregate 12 functions as a metal and becomes hot metal. Since the aggregate 12 has a high metallization rate and does not need to be reduced, it does not require a large amount of reducing material when it becomes the hot metal. Therefore, CO2 emissions can be reduced.
- "metallization ratio” means the ratio [mass %] of metallic iron to the total iron content.
- the upper limit of the average basicity of the reduced iron compact is 0.5, more preferably 0.4.
- Reduced iron compacts contain SiO 2 and Al 2 O 3 as iron ore-derived slag components, and generally tend to have a low average basicity.
- SiO 2 and Al 2 O 3 are removed, or CaO is added to increase the basicity, resulting in a high-grade cast iron.
- the lower limit of the average basicity of the reduced iron compact is not particularly limited, and may be zero.
- a ratio R of the basic unit of the iron ore pellets to the basic unit of the reduced iron compact preferably satisfies the following formula 1.
- the ratio R of the basic unit of the iron ore pellets to the basic unit of the reduced iron compact satisfies the following formula 1, so that the effect of improving the permeability due to the burn-through of the reduced iron compact can be more reliably expressed. be able to.
- FIG. 3 is a graph showing the relationship between the average basicity of HBI and the maximum pressure drop of the packed bed in which the first layers 10 and the second layers 20 are alternately laminated. It can be determined that the smaller the maximum pressure loss, the higher the air permeability. From FIG. 3, it can be seen that when the average basicity of HBI exceeds a certain value, the air permeability is improved. This constant value is the critical basicity. It is believed that when CaO having a critical basicity or higher is present, SiO 2 in HBI changes to a calcium silicate-based melt, lowering the viscosity of molten iron produced from HBI and promoting burn-through. In other words, it can be said that CaO having a critical basicity or more is necessary to obtain the HBI burn-through promoting effect.
- CaO is supplied from HBI, but CaO can also be supplied from iron ore pellets. Then, if the amount of CaO exceeds the critical basicity with respect to the amount of SiO 2 combined with HBI and iron ore pellets, it is believed that the burn-through of HBI is promoted and the air permeability of the filling layer can be enhanced.
- the amount of SiO2 and the amount of CaO, which are the sum of HBI and iron ore pellets, are expressed by the following formula 2, where the unit consumption of reduced iron compacts is M HBI [kg] and the unit consumption of iron ore pellets is M P [kg]. be done.
- the lower limit of the charging amount of the reduced iron compact is preferably 100 kg, more preferably 150 kg, per ton of pig iron. If the charged amount of the reduced iron compact is less than the above lower limit, the function of ensuring the permeability of the aggregate 12 in the cohesive zone D may not work sufficiently in the reduction melting step S2. On the other hand, the charging amount of the reduced iron compacts is appropriately determined within a range in which the aggregate effect is not reduced due to excessive aggregate. It is said that
- the lower limit of the ratio of the average particle size of the reduced iron compact to the average particle size of the ore raw material 11 is preferably 1.3, more preferably 1.4.
- part of the ore raw material 11 of the first layer 10 melts and moves to the lower part of the blast furnace 1 as the dripping slag 13, and even when the ore raw material 11 softens and shrinks, the above-mentioned reduction of the high melting point Iron compacts do not soften.
- the above-mentioned reduced iron compact having a certain size or more is mixed as the aggregate 12 with respect to the ore raw material 11, the aggregate effect of the above-mentioned reduced iron compact is likely to be exhibited, and layer shrinkage of the entire first layer 10 can be suppressed. .
- the ratio of the average particle diameters is preferably 10 or more preferably 5. If the average particle size ratio exceeds the upper limit, it may be difficult to uniformly mix the reduced iron compact in the first layer 10, and segregation may increase.
- the term "average particle size" refers to the particle size at which the cumulative mass is 50% in the particle size distribution.
- the upper limit of the ventilation resistance index after the tumbler rotation test of the reduced iron compact is preferably 0.1, more preferably 0.08.
- the above reduced iron compacts are generally transported to different factories than where they are manufactured. During this time, the particle size distribution can change due to volume collapse, so by using a reduced iron compact that ensures that the airflow resistance index is below a certain value even after the tumbler rotation test, it is possible to use a reduced iron compact that will be described later in actual blast furnace operation.
- the air permeability in the massive band E can be improved.
- the lower limit of the air permeability resistance index is not particularly limited, and may be a value close to 0, which is the theoretical limit value under definition, but is usually about 0.03. It should be noted that it is sufficient that the reduced iron molded body has properties such that the airflow resistance index is equal to or less than a predetermined value, and it does not mean that the tumbler rotation test is required in the pig iron manufacturing method.
- the "airflow resistance index after the tumbler rotation test" of the reduced iron compact is calculated as follows. First, a tumbler rotation test is performed according to the rotational strength measurement method for iron ores (JIS-M8712:2000), and the particle size distribution is obtained by sieving the reduced iron compact. This particle size distribution is represented by d i [cm] as the representative particle size (median value) between the sieved meshes, and wi as the weight fraction of the reduced iron compact belonging to the representative particle size d i . . Using this particle size distribution, the harmonic mean diameter D p [cm] and the particle size composition index I sp are calculated according to Equation 3 below.
- the ventilation resistance index K is obtained by the following equation 3.
- the tumbler rotation conditions in the tumbler rotation test are 24 ⁇ 1 rpm and 600 rotations.
- the upper limit of the aluminum oxide content in the reduced iron compact is preferably 1.5% by mass, more preferably 1.3% by mass. If the content of aluminum oxide exceeds the upper limit, it may become difficult to ensure air permeability in the lower part of the furnace due to an increase in the melting point of the slag and an increase in viscosity. Therefore, by setting the content of aluminum oxide in the reduced iron compact to the above upper limit or less, it is possible to suppress an increase in the amount of coke used.
- the aluminum oxide content may be 0% by mass, that is, the reduced iron compact may not contain aluminum oxide, but the lower limit of the aluminum oxide content is 0.5% by mass. preferable. If the content of aluminum oxide is less than the above lower limit, the reduced iron compact becomes expensive, and the production cost of the pig iron may increase.
- the second layer 20 contains coke 21 .
- the coke 21 is a heat source for melting the ore raw material 11 , a reducing agent necessary for reducing the ore raw material 11 , a recarburizing agent for carburizing molten iron and lowering the melting point, and a recarburizing agent for reducing the melting point of the molten iron. It acts as a spacer to ensure breathability.
- the raw material charging device 2 is provided at the top of the furnace. That is, the first layer 10 and the second layer 20 are charged from the furnace top.
- the raw material charging device 2, as shown in FIG. 2, has a bell cup 2a, a lower bell 2b, and an armor 2c.
- the bell cup 2a is filled with raw materials to be charged.
- the raw material constituting the first layer 10 is filled into the bell cup 2a, and when charging the second layer 20, the raw material constituting the second layer 20 is filled.
- the lower bell 2b has a conical shape that spreads downward and is arranged inside the bell cup 2a.
- the lower bell 2b can move up and down (in FIG. 2, a solid line indicates an upward movement, and a broken line indicates a downward movement).
- a solid line indicates an upward movement
- a broken line indicates a downward movement
- the armor 2c is provided on the furnace wall of the blast furnace 1 below the lower bell 2b. When the lower bell 2b is moved downward, raw materials fall through the gap, and the armor 2c is a repulsion plate for repelling the falling raw materials. In addition, the armor 2c is configured to be protrusive and retractable toward the interior (central portion) of the blast furnace 1 .
- the first layer 10 can be laminated as follows. Note that the same applies to the second layer 20 as well. Moreover, lamination
- the lower bell 2b is positioned upward, and the raw material for the first layer 10 is charged into the bell cup 2a.
- the lower bell 2b is positioned upward, the lower portion of the bell cup 2a is closed, so the bell cup 2a is filled with the raw material.
- the filling amount be the lamination amount of each layer.
- the lower bell 2b moves downward.
- a gap is created between the bell cup 2a and the raw material drops from the gap toward the furnace wall and collides with the armor 2c.
- the raw material that collides with and repels the armor 2c is charged into the furnace. Since the raw material drops while moving toward the inside of the furnace due to the repulsion of the armor 2c, the raw material is deposited while flowing toward the center of the furnace from the dropped position. Since the armor 2c is configured to be retractable toward the central portion, the dropping position of the raw material can be adjusted by extending and retracting the armor 2c. This adjustment allows the first layer 10 to be deposited in a desired shape.
- the reduction melting step S2 hot air blown from the tuyeres 1a blows auxiliary fuel into the blast furnace, and the ore raw material 11 of the first layer 10 is reduced and melted.
- the blast furnace operation is a continuous operation, and the reduction melting step S2 is continuously performed.
- the stacking step S1 is intermittently performed, and depending on the state of the reduction and dissolution treatment of the first layer 10 and the second layer 20 in the reduction and dissolution step S2, a new layer to be processed in the reduction and dissolution step S2 is added.
- One layer 10 and a second layer 20 are added.
- FIG. 2 shows the state in the reduction dissolution step S2.
- the hot air from the tuyere 1a forms a raceway A, which is a hollow portion in which the coke 21 is swirling and exists in a remarkably sparse state, in the vicinity of the tuyere 1a.
- the temperature of the raceway A is the highest and is about 2000°C.
- Adjacent to the raceway A there is a core B, which is a pseudo-stagnation zone of coke inside the blast furnace 1 .
- a dripping zone C Adjacent to the raceway A, there is a core B, which is a pseudo-stagnation zone of coke inside the blast furnace 1 .
- a dripping zone C Adjacent to the raceway A, there are a dripping zone C, a cohesive zone D, and a massive zone E in this order.
- the temperature inside blast furnace 1 rises from the top toward raceway A. That is, the temperature of the massive zone E, the cohesive zone D, and the dropping zone C is higher in this order. .
- the temperature of the core B varies in the radial direction, and the temperature at the center of the core B may be lower than that of the dropping zone C in some cases.
- a cohesive zone D having an inverted V-shaped cross section is formed to ensure air permeability and reducing properties in the furnace.
- the iron ore raw material 11 is first subjected to temperature-rising reduction in the massive zone E.
- the cohesive zone D the ore reduced in the massive zone E softens and shrinks.
- the ore that has softened and shrunk descends to become dripping slag and moves to dripping zone C.
- the reduction dissolution step S2 the reduction of the ore raw material 11 proceeds mainly in the massive zone E, and the dissolution of the ore raw material 11 mainly occurs in the dripping zone C.
- the dropping zone C and the core B the direct reduction in which the falling liquid iron oxide FeO directly reacts with the carbon of the coke 21 proceeds.
- the aggregate 12 containing the reduced iron compact exhibits an aggregate effect in the cohesive zone D. In other words, even when the ore softens and shrinks, the high-melting reduced iron molded body does not soften, and an air passage for reliably ventilating the hot air to the center of the blast furnace 1 is secured.
- the above-mentioned reduced iron compact has a high melting point, but due to the carburizing reaction from carbon monoxide CO in the reducing gas and carbon in the coke, the melting point is lowered and in the temperature region below the cohesive zone D of about 1500 ° C. It becomes molten iron. Even at this point, the slag component SiO 2 contained in the reduced iron molded body exists in a solid state, and is in a state of solid-liquid coexistence with the molten iron from the reduced iron molded body that has previously melted, and is in a highly viscous state, and meltdown stagnates. do.
- molten iron F that is molten reduced iron is deposited, and molten slag G is deposited on the upper part of the molten iron F.
- the molten iron F and molten slag G can be taken out from the tap hole 1b.
- the auxiliary fuel injected from the tuyeres 1a includes pulverized coal obtained by finely pulverizing coal to a particle size of about 50 ⁇ m, heavy oil, natural gas, and the like.
- the auxiliary fuel functions as a heat source, reducing agent and recarburizing agent. That is, among the roles played by the coke 21, it replaces roles other than the spacer.
- the first layer 10 containing the ore raw material 11 contains, as the aggregate 12, a reduced iron compact obtained by compression molding reduced iron.
- This reduced iron compact makes it easier for hot air to pass through when the first layer 10 is softened and fused in the reduction melting step S2.
- the reduced iron compact since the reduced iron compact having an average basicity of 0.5 or less is used, the reduced iron compact can be obtained at a relatively low cost.
- the pig iron production method by using iron ore pellets having an average basicity of 0.9 or more as the main raw material, an increase in viscosity when the reduced iron compact having a low average basicity is dissolved is suppressed, promote falling.
- the air permeability of the cohesive zone D is mainly improved, and the amount of coke used can be reduced. Therefore, by using the pig iron production method, it is possible to reduce the amount of coke used while maintaining stable operation of the blast furnace 1 .
- the ore raw materials of all the first layers to be laminated are mainly made of iron ore pellets, the average basicity of the reduced iron compact is 0.5 or less, and the average basicity of the iron ore pellets is 0.9 or more, but in the present invention, the ore raw material of at least one first layer is mainly made of iron ore pellets, and the average basicity of the reduced iron compact is 0.5 below and the average basicity of the iron ore pellets is 0.9 or more.
- the first layer having the above configuration is preferably 90% or more, more preferably 95% or more, and 100%, that is, all layers The first layer having the above configuration is more preferable.
- the pig iron production method of the present invention includes only the lamination step and the reduction melting step, but the pig iron production method may include other steps.
- the method for producing pig iron may include a step of charging a mixture of coke and reduced iron compacts into the center of the blast furnace.
- the proportion of reduced iron compacts having a particle size of 5 mm or more is 90% by mass or more, and the content of the reduced iron compacts in the mixture is 75% by mass or less. is preferably
- the hot air reaches the center of the blast furnace, it rises in the center.
- the reduced iron compact having a large particle size in the central part in a content equal to or less than the above upper limit the sensible heat can be effectively utilized without interfering with the flow of the hot air. Therefore, the amount of coke used can be further reduced.
- the "central part" of the blast furnace refers to a region whose distance from the center is 0.2Z or less, where Z is the radius of the throat.
- the method for producing pig iron may include a step of finely pulverizing powder and coal derived from the reduced iron compact.
- the fine powder obtained in the pulverization step is preferable to include the fine powder obtained in the pulverization step as the auxiliary fuel.
- a portion of the reduced iron compact is crushed during the transportation process or the like to become powder. Since such powder reduces the air permeability in the blast furnace, it is not suitable for use as the first layer.
- this powder has a large specific surface area, it is re-oxidized into iron oxide. Air permeability can be improved by blowing supplementary fuel containing iron oxide through the tuyeres.
- the powder derived from the reduced iron compact is pulverized together with coal, and the finely pulverized powder and the fine powder containing the coal are used as auxiliary fuel for blowing through the tuyeres, thereby effectively utilizing the reduced iron compact. can be achieved, and the air permeability in the blast furnace can be improved.
- a bell-less system can be cited as such another system.
- a revolving chute is used, and stacking can be performed while adjusting the angle of the chute.
- Fig. 5 shows the large-scale load reduction experimental furnace 7 used in this experiment.
- the inner diameter of the graphite crucible 71 filled with the sample was set to ⁇ 75 mm.
- the sample packed layer 72 consisted of an upper coke layer 72a (height 20 mm), an ore layer 72b (height 110 mm) and a lower coke layer 72c (height 40 mm) from the top.
- the ore layer 72b corresponds to the first layer 10 of the present invention
- the upper coke layer 72a and the lower coke layer 72c correspond to the second layer 20 of the present invention.
- the ore layer 72b is a mixture of a reduced iron compact (HBI) and an ore raw material.
- the ore layer 72b has a constant total iron content (T.Fe).
- Table 1 shows the chemical properties of the HBI used.
- the average basicity of HBI is 0.46.
- the charging amount of HBI was 250 kg per ton of pig iron.
- the pressure loss of the sample packed layer 72 was continuously measured under the above conditions, and the time integral value (S value) of the pressure loss was calculated.
- the S value can be used as an evaluation index for the softening and melting behavior of the ore layer 72b, and it is considered that the smaller the value, the higher the air permeability. The results are shown in FIG.
- the S value is in the order of iron ore pellets with an average basicity of 1.20 ⁇ iron ore pellets with an average basicity of 0.04 ⁇ self-fluxing sinter with an average basicity of 2.10, and the average It can be seen that air permeability is improved by using iron ore pellets having a basicity of 0.9 or more as an ore raw material.
- the critical basicity of the HBI used is 0.88, and the basicity determined from the amount of CaO and the amount of SiO2 calculated based on the above formula 2 should be equal to or higher than the critical basicity of HBI, that is, the above formula 1 It can be said that the air permeability is improved by satisfying
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Abstract
Description
高炉1は、図2に示すように、炉下部に設けられた羽口1aと、出銑口1bとを有する。羽口1aは通常複数設けられる。高炉1は、固気向流型のシャフト炉であり、高温の空気に、必要に応じて高温又は常温の酸素を加えた熱風を羽口1aから炉内に吹き込んで、後述する鉱石原料11の還元及び溶融等の一連の反応を行い、出銑口1bから銑鉄を取り出すことができる。また、高炉1には、ベル・アーマー方式の原料装入装置2が装備されている。この原料装入装置2については、後述する。
積層工程S1では、図2に示すように、高炉1内に第1層10と第2層20とを交互に積層する。つまり、第1層10及び第2層20の層数は、それぞれ2以上である。
第1層10は、鉱石原料11を含む。また、第1層10には、骨材12が混合されている。第1層10には、鉱石原料11及び骨材12に加えて、石灰石、ドロマイト、珪石等の副原料を一緒に装入してもよい。
第2層20はコークス21を含む。
第1層10及び第2層20を交互に積層する方法は、種々の方法を用いることができる。ここでは、図2に示すようなベル・アーマー方式の原料装入装置2(以下、単に「原料装入装置2」ともいう)を搭載した高炉1を例にとり、その方法について説明する。
還元溶解工程S2では、羽口1aから送風する熱風により補助燃料を高炉内へ吹込みつつ、積層された第1層10の鉱石原料11を還元及び溶解する。なお、高炉操業は連続操業であり、還元溶解工程S2は連続して行われている。一方、積層工程S1は間欠的に行われており、還元溶解工程S2で第1層10及び第2層20の還元及び溶解処理の状況に応じて、新たに還元溶解工程S2で処理すべき第1層10及び第2層20が追加されていく。
当該銑鉄製造方法では、鉱石原料11を含む第1層10が、骨材12として還元鉄を圧縮成形した還元鉄成形体を含む。この還元鉄成形体により、還元溶解工程S2で第1層10の軟化融着時に熱風が通過し易くなるため、当該銑鉄製造方法では、通気性を確保するためのコークスの量が少なくて済む。また、当該銑鉄製造方法では、平均塩基度が0.5以下の還元鉄成形体を用いるので、比較的安価に還元鉄成形体を入手することができる。さらに、当該銑鉄製造方法では、平均塩基度が0.9以上の鉄鉱石ペレットを主原料として用いることで、平均塩基度が低い還元鉄成形体が溶解した際の粘性の増大を抑止し、溶け落ちを促進する。これにより主に融着帯Dの通気性が改善され、さらにコークスの使用量を低減することができる。従って、当該銑鉄製造方法を用いることで高炉1の安定操業を維持しつつコークスの使用量を低減することができる。
なお、本発明は、上記実施形態に限定されるものではない。
1a 羽口
1b 出銑口
2 原料装入装置
2a ベルカップ
2b 下ベル
2c アーマー
10 第1層
11 鉱石原料
12 骨材
13 滴下スラグ
20 第2層
21 コークス
7 大型荷重還元実験炉
71 黒鉛坩堝
72 試料充填層
72a 上部コークス層
72b 鉱石層
72c 下部コークス層
73 電気炉
74 ガス供給管
75 ガス排出管
76 熱電対
77 荷重棒
78 錘
A レースウェイ
B 炉心
C 滴下帯
D 融着帯
E 塊状帯
F 溶銑
G 溶融スラグ
Claims (4)
- 羽口を有する高炉を用いて銑鉄を製造する銑鉄製造方法であって、
上記高炉内に鉱石原料を含む第1層とコークスを含む第2層とを交互に積層する工程と、
上記羽口から送風する熱風により補助燃料を上記高炉内へ吹込みつつ、積層された上記第1層の上記鉱石原料を還元及び溶解する工程と
を備え、
還元鉄を圧縮成形した還元鉄成形体を含む骨材が上記第1層に混合されており、
上記鉱石原料が鉄鉱石ペレットを主原料とし、
上記還元鉄成形体の平均塩基度が0.5以下であり、
上記鉄鉱石ペレットの平均塩基度が0.9以上である銑鉄製造方法。 - 上記鉱石原料における上記鉄鉱石ペレットの含有量が50質量%以上である請求項1に記載の銑鉄製造方法。
- 上記鉄鉱石ペレットが自溶性である請求項1に記載の銑鉄製造方法。
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EP21933163.4A EP4289977A1 (en) | 2021-03-26 | 2021-05-10 | Pig iron production method |
CN202180093630.6A CN116829739A (zh) | 2021-03-26 | 2021-05-10 | 生铁制造方法 |
US18/551,306 US20240167109A1 (en) | 2021-03-26 | 2021-05-10 | Method for producing pig iron |
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EP (1) | EP4289977A1 (ja) |
JP (1) | JP2022150455A (ja) |
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Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH11315308A (ja) | 1998-05-01 | 1999-11-16 | Nippon Steel Corp | 高炉の操業方法 |
JP2009102746A (ja) * | 2007-09-14 | 2009-05-14 | Nippon Steel Corp | 銑鉄の製造方法 |
JP2009149942A (ja) * | 2007-12-20 | 2009-07-09 | Kobe Steel Ltd | 高炉用自溶性ペレットおよびその製造方法 |
-
2021
- 2021-03-26 JP JP2021053067A patent/JP2022150455A/ja active Pending
- 2021-05-10 CN CN202180093630.6A patent/CN116829739A/zh active Pending
- 2021-05-10 US US18/551,306 patent/US20240167109A1/en active Pending
- 2021-05-10 WO PCT/JP2021/017701 patent/WO2022201562A1/ja active Application Filing
- 2021-05-10 KR KR1020237029168A patent/KR20230136640A/ko unknown
- 2021-05-10 EP EP21933163.4A patent/EP4289977A1/en active Pending
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH11315308A (ja) | 1998-05-01 | 1999-11-16 | Nippon Steel Corp | 高炉の操業方法 |
JP2009102746A (ja) * | 2007-09-14 | 2009-05-14 | Nippon Steel Corp | 銑鉄の製造方法 |
JP2009149942A (ja) * | 2007-12-20 | 2009-07-09 | Kobe Steel Ltd | 高炉用自溶性ペレットおよびその製造方法 |
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