WO2023054588A1 - 製鉄方法 - Google Patents
製鉄方法 Download PDFInfo
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- WO2023054588A1 WO2023054588A1 PCT/JP2022/036451 JP2022036451W WO2023054588A1 WO 2023054588 A1 WO2023054588 A1 WO 2023054588A1 JP 2022036451 W JP2022036451 W JP 2022036451W WO 2023054588 A1 WO2023054588 A1 WO 2023054588A1
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- Prior art keywords
- iron
- goethite
- mass
- rich portion
- rich
- Prior art date
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- 238000000034 method Methods 0.000 title claims abstract description 58
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 289
- 229910052742 iron Inorganic materials 0.000 claims abstract description 126
- 239000008188 pellet Substances 0.000 claims abstract description 90
- 229910052598 goethite Inorganic materials 0.000 claims abstract description 70
- AEIXRCIKZIZYPM-UHFFFAOYSA-M hydroxy(oxo)iron Chemical compound [O][Fe]O AEIXRCIKZIZYPM-UHFFFAOYSA-M 0.000 claims abstract description 70
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 63
- 239000007789 gas Substances 0.000 claims abstract description 51
- 230000009467 reduction Effects 0.000 claims abstract description 35
- 229910052500 inorganic mineral Inorganic materials 0.000 claims abstract description 32
- 239000011707 mineral Substances 0.000 claims abstract description 32
- 238000005054 agglomeration Methods 0.000 claims abstract description 21
- 230000002776 aggregation Effects 0.000 claims abstract description 21
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 15
- 238000010304 firing Methods 0.000 claims abstract description 11
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 11
- 239000001257 hydrogen Substances 0.000 claims abstract description 11
- 229910052595 hematite Inorganic materials 0.000 claims description 41
- 239000011019 hematite Substances 0.000 claims description 41
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 claims description 41
- 238000004519 manufacturing process Methods 0.000 claims description 31
- 238000001465 metallisation Methods 0.000 claims description 26
- 238000005406 washing Methods 0.000 claims description 9
- 238000009628 steelmaking Methods 0.000 claims description 2
- 238000002425 crystallisation Methods 0.000 abstract description 8
- 230000008025 crystallization Effects 0.000 abstract description 8
- 239000002994 raw material Substances 0.000 description 55
- 239000002245 particle Substances 0.000 description 33
- 230000005484 gravity Effects 0.000 description 28
- 230000008569 process Effects 0.000 description 17
- 239000007788 liquid Substances 0.000 description 15
- 239000000203 mixture Substances 0.000 description 15
- 230000005291 magnetic effect Effects 0.000 description 7
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 6
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 6
- 229910000831 Steel Inorganic materials 0.000 description 5
- 238000000926 separation method Methods 0.000 description 5
- 239000002002 slurry Substances 0.000 description 5
- 239000010959 steel Substances 0.000 description 5
- 102220486681 Putative uncharacterized protein PRO1854_S10A_mutation Human genes 0.000 description 3
- 239000002734 clay mineral Substances 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 239000000428 dust Substances 0.000 description 3
- 238000005265 energy consumption Methods 0.000 description 3
- 239000003345 natural gas Substances 0.000 description 3
- 238000011946 reduction process Methods 0.000 description 3
- 230000000630 rising effect Effects 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 229910000805 Pig iron Inorganic materials 0.000 description 2
- 102220470087 Ribonucleoside-diphosphate reductase subunit M2_S20A_mutation Human genes 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 2
- 238000007667 floating Methods 0.000 description 2
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- MODGUXHMLLXODK-UHFFFAOYSA-N [Br].CO Chemical compound [Br].CO MODGUXHMLLXODK-UHFFFAOYSA-N 0.000 description 1
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 description 1
- 229910052601 baryte Inorganic materials 0.000 description 1
- 239000010428 baryte Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 230000005294 ferromagnetic effect Effects 0.000 description 1
- 239000011344 liquid material Substances 0.000 description 1
- 239000006249 magnetic particle Substances 0.000 description 1
- 238000007885 magnetic separation Methods 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 238000005456 ore beneficiation Methods 0.000 description 1
- 230000005298 paramagnetic effect Effects 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 210000003462 vein Anatomy 0.000 description 1
- 239000002699 waste material 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
- C21B5/001—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
-
- 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
-
- 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
-
- 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
- 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
- C21B2005/005—Selection or treatment of the reducing gases
Definitions
- the present invention relates to an iron manufacturing method.
- This application claims priority based on Japanese Patent Application No. 2021-159551 filed in Japan on September 29, 2021, the content of which is incorporated herein.
- the direct reduction ironmaking method is known as one of the ironmaking methods for obtaining iron from raw materials containing iron oxide (reducing iron oxide).
- the direct reduction ironmaking process has continued to develop against the background of the low construction cost of the plant for this process, the ease of operation, and the ability to operate in a small-scale plant.
- various improvements have been made to effectively utilize the reducing gas in the furnace.
- Typical examples include HYBRIT and MIDREX+ H2 , which utilize hydrogen obtained by electrolysis of water in a shaft furnace type direct reduction ironmaking process.
- DRI Direct Reduction Iron
- DRI Direct Reduction Iron
- the energy consumption rate during electric furnace operation increases, Cost increases (for example, Non-Patent Document 1).
- blast furnaces use unreduced iron ore, sintered ore, and pellets with a high gangue content. Units do not increase. Rather, replacing iron ore, sintered ore, and pellets with DRI reduces the energy consumption rate (for example, Non-Patent Document 2).
- DR pellets with a low gangue amount are used in the direct reduction ironmaking process.
- DR pellets are manufactured from iron ore (concentrate) that has been enriched by magnetic or gravity beneficiation, but DR pellets are produced only from raw ore with good gangue separability produced in specific areas. of concentrate cannot be produced.
- Australian iron ore is not beneficiated because it is difficult to separate the gangue, resulting in a large amount of gangue. Furthermore, in recent years, not only iron ore produced in Australia, but also iron ore raw materials have deteriorated in quality. Along with this, the amount of iron ore gangue is increasing, and it is estimated that the production of DR pellets will become increasingly difficult in the future. Iron ore of inferior quality, including Australian iron ore, contains a large amount of water of crystallization.
- the present invention has been made in view of the above problems, and an object of the present invention is to provide a new and improved iron ore raw material capable of efficiently agglomerating and reducing iron ore raw materials of inferior quality. It is to provide a method of making iron.
- the gist of the present invention is as follows.
- high-crystal-water iron ore having an ignition loss of 3 to 12 mass% is beneficiated into a goethite-rich portion having an ignition loss of at least 4 mass% and an iron content of 55 mass% or more.
- a first agglomeration treatment step in which the goethite-rich portion is agglomerated into first fired pellets in a pellet firing furnace; C. or higher and directly reduced using a reducing gas containing 60% by volume or more of hydrogen.
- the first fired pellets may be directly reduced to a metallization rate of 60% to 95%.
- Aspect 3 of the present invention is the iron manufacturing method of aspect 1 or 2, wherein in the ore dressing step, a hematite-rich portion having an ignition loss of less than 4% by mass and an iron content of 55% by mass or more is further beneficiated, It may further comprise a second agglomeration treatment step of agglomerating the part into second fired pellets in a pellet firing furnace.
- Aspect 4 of the present invention is the steelmaking method of aspect 3, wherein the second fired pellets are directly reduced in a shaft furnace using a reducing gas containing 60% by volume or more of hydrogen to obtain a metallization rate of 90% or more. You may further have a 2nd reduction process set as direct reduced iron.
- Aspect 5 of the present invention is the iron manufacturing method according to any one of Aspects 1 to 4, further comprising a washing treatment step of removing tailings from the high-crystalline water iron ore before the mineral beneficiation treatment step.
- the numerical range shown using “-" includes the numerical value of both ends of "-".
- the percentage (%) of each component such as iron ore in the table means % by mass with respect to the total mass of iron ore and the like.
- the iron content is measured according to JIS M 8212: 2005 iron ore-total iron determination method.
- loss of ignition (LOI) is regarded as the content of water of crystallization. Loss on ignition (LOI) is defined as the mass reduction rate when iron ore is held at 1000° C. for 60 minutes.
- the agglomeration method and reduction method according to the present embodiment are iron manufacturing methods that utilize iron ore containing a large amount of water of crystallization, for example, goethite-containing iron ore from Australia, which has abundant reserves.
- an iron ore raw material is separated into a goethite-rich portion mainly composed of goethite by beneficiation.
- the beneficiation process it may be separated into a hematite-rich portion mainly composed of hematite, a goethite-rich portion mainly composed of goethite, and a gangue-rich portion mainly composed of gangue.
- the hematite-rich portion is a portion having an LOI of less than 4% by mass and an iron content of 55% by mass or more
- the goethite-rich portion is a portion having an LOI of 4% by mass or more and an iron content of 55% by mass or more
- a rich portion is a portion having an iron content of less than 55% by mass.
- the hematite-rich portion is a portion of the high crystalline water iron ore that is mainly composed of hematite, and refers to a portion of the high crystalline water iron ore having an LOI of less than 4% by mass and an iron content of 55% by mass or more.
- the portion mainly composed of hematite refers to a portion having a hematite content of 50% by mass or more with respect to the total mass of the portion.
- the goethite-rich portion is a portion of the high crystalline water iron ore that is mainly composed of goethite, and refers to a portion of the high crystalline water iron ore having an LOI of 4% by mass or more and an iron content of 55% by mass or more.
- the part mainly composed of goethite means that the content of goethite is 50% by mass or more with respect to the total mass of the part.
- the gangue-rich portion is a portion of the high crystalline water iron ore in which gangue is the main constituent, and refers to a portion of the high crystalline water iron ore having an iron content of less than 55% by mass.
- a part mainly composed of gangue means that the content of gangue is 50% by mass or more with respect to the total mass of the part.
- high-crystal-water iron ore containing a large amount of crystal water (here, LOI is regarded as its content) by EDS (energy dispersive X-ray spectroscopy) was analyzed, identification of mineral phases, composition of each phase, etc. were analyzed.
- high crystal water iron ore refers to iron ore containing 3 to 12% by mass of water of crystallization. That is, in the present specification, the ignition loss of the high crystalline water iron ore is 3 to 12% by mass.
- the high crystalline water iron ore contains a hematite-rich part mainly composed of hematite, a goethite-rich part mainly composed of goethite, and a gangue-rich part mainly composed of gangue. was present in goethite-rich and gangue-rich areas.
- the inventor of the present invention came up with the following idea. That is, the high-crystal-water iron ore is subjected to beneficiation treatment by specific gravity, and the divided portion is determined to be any of the hematite-rich portion, the goethite-rich portion, and the gangue-rich portion, and the hematite-rich portion and the goethite-rich portion are determined. are separately agglomerated and reduced by suitable methods.
- the hematite-rich portion contains a large amount of iron, by agglomerating it into fired pellets and directly reducing it in a shaft furnace to make reduced iron, it can be used as a raw material for electric furnaces with the same quality as conventional DR pellets.
- the goethite-rich part has a relatively low iron content, so it is converted to semi-reduced iron and used as raw material for blast furnaces.
- the high crystalline water iron ore can be efficiently produced.
- the sintered pellets derived from the goethite-rich part are inferior to the conventional sintered pellets derived from hematite and magnetite in terms of strength and reduction pulverization due to the detachment of water of crystallization.
- the goethite-rich portion may be used as a raw material for sintered ore. This also avoids the aforementioned problems associated with using pellets made from goethite-rich sections in shaft furnaces.
- the iron ore (iron ore raw material) to be treated in the present embodiment is the above-described high-crystalline water iron ore.
- High crystal water iron ore contains 3 to 12% by mass of water of crystallization.
- the mass % of water of crystallization is measured as loss on ignition (LOI).
- LOI loss on ignition
- High crystalline water iron ores often contain 55-67 mass % iron.
- An example of a high crystalline water iron ore is the Australian iron ore Brockmannite having the components shown in Table 1.
- the grain size of the high crystalline water iron ore is not particularly limited.
- a raw material of high crystalline water iron ore mined from a vein is first coarsely crushed.
- the lump ore for blast furnace is extracted, it is pulverized to a particle size of 50 mm or less, and the lump ore with a particle size of 50 mm to 10 mm is recovered as a lump ore with a particle size of less than 10 mm as fine ore.
- the high-crystalline-water iron ore used as the starting material for the embodiment of the present invention may be either coarsely pulverized from which no lump ore is extracted, or fine ore.
- FIG. 1 shows the overall flow of the agglomeration method S10 and the reduction method S20 in the ironmaking method according to the present embodiment.
- FIG. 2 shows the overall flow of another agglomeration method S10A and reduction method S20A in the ironmaking method according to this embodiment.
- the agglomeration method S10 includes a water washing treatment step S1, a mineral beneficiation treatment step S2, and a first agglomeration treatment step S3B.
- the agglomeration method S10 may further include a sintered ore production step S4.
- the agglomeration method S10A in which the hematite-rich portion is also beneficiated and agglomerated, includes a water washing process S1, a beneficiation process S2, a first agglomeration process S3B, and a second agglomeration process S3A. ,including.
- a high crystalline water iron ore which is an iron ore raw material, is separated into a plurality of pieces using a gravity separation method. Then, the separated site is determined from the iron content and the LOI for the goethite-rich site. Whether the separated portion is a hematite-rich portion, a goethite-rich portion, or a gangue-rich portion may be determined from the iron content and the LOI.
- the hematite-rich portion is a portion having an LOI of less than 4% by mass and an iron content of 55% by mass or more
- the goethite-rich portion is a portion having an LOI of 4% by mass or more and an iron content of 55% by mass or more
- a rich portion is a portion having an iron content of less than 55% by mass.
- the separated goethite-rich portion is agglomerated according to the flow of FIG. Each of the separated parts may be individually agglomerated according to the flow of FIG.
- the hematite-rich portion is agglomerated into second fired pellets in a pellet firing furnace.
- the goethite-rich portion is agglomerated into first fired pellets in a pellet firing furnace.
- the goethite-rich portion may be made into sintered ore by a sintering machine. Depending on the iron content of the gangue-rich portion, it may be discarded or used as raw material for sinter ore.
- Clay minerals can be removed from high crystalline water iron ore by water washing. Specifically, for example, the iron ore raw material is washed with water using a drum type scrubber or a washing sieve. Thereby, clay minerals (so-called tailings) with a particle size of 20 to 45 ⁇ m or less adhering to the surface of the iron ore raw material can be washed away. Tailings are low in iron and should be discarded.
- Table 2 shows an example of the results of water washing treatment. As is clear from Table 2, by removing clay minerals in advance, the iron content of the iron ore raw material can be increased and the gangue component can be reduced.
- the washed iron ore raw material is beneficiated and separated into a plurality of parts.
- the high-crystal-water iron ore is beneficiated into a goethite-rich portion having an iron content of at least 55% by mass or more.
- the high crystalline water iron ore is divided into a hematite-rich portion having an ignition loss LOI of less than 4% by mass and an iron content of 55% by mass or more, and a goethite-rich portion having an ignition loss LOI of 4% by mass or more and an iron content of 55% by mass or more. Beneficiation may be done in part and part.
- the high-crystalline-water iron ore may be further beneficiated into a gangue-rich portion having an iron content of less than 55% by mass. Then, the LOI and iron content of each separated portion are analyzed to determine to which of the hematite-rich portion, goethite-rich portion, and gangue-rich portion it belongs.
- gravity beneficiation treatment gravity separation treatment
- the iron ore raw material into a hematite-rich portion, a goethite-rich portion, and a gangue-rich portion.
- Magnetic beneficiation may be performed together with specific gravity beneficiation.
- an iron ore raw material is classified with a grain size of about 3 mm.
- Classification may be performed with a sieve.
- the iron ore raw materials above the sieve and below the sieve are preferably subjected to specific gravity beneficiation by the following methods.
- Above sieve JIG or heavy liquid separation
- Below sieve Spiral, Up-current classifiers (UCC), Wet High Intensity Magnetic Separation (WHIMS) or heavy liquid separation
- UCC Up-current classifiers
- WHIMS Wet High Intensity Magnetic Separation
- JIG JIG is a type of specific gravity beneficiation process, and is a method of sorting mineral particles by utilizing the difference in specific gravity.
- Mineral particles are supplied to a bed of particles with a mesh bottom.
- water is intermittently flowed from the bottom to the top to raise the water level. This causes the mineral particles to be hoisted into the water and temporarily suspended. Then stop the water flow. This causes the mineral particles to re-sett on the net as the water level descends and returns.
- the higher the specific gravity of the mineral particles the faster the mineral particles fall, so mineral particles with higher specific gravity gather at the bottom of the particle layer after settling.
- the mineral particles can be concentrated by specific gravity. That is, by extracting the desired mineral particles from each of the formed particle layers, the mineral particles can be sorted according to their specific gravity.
- Spiral is a type of specific gravity beneficiation process, and is a beneficiation method that utilizes centrifugal force generated in slurry (a mixture of water and mineral particles) flowing through a spiral trough.
- slurry a mixture of water and mineral particles
- the beneficiation efficiency is controlled by adjusting the feed size and the amount of water in the trough.
- UCC UCC is also a type of gravity beneficiation process.
- a slurry mixture of water and mineral particles
- an upward stream of water is supplied from the bottom.
- these particles interact and come into contact with each other, and the mineral particles with a low specific gravity ride on the rising water flow, so that they can be separated from other mineral particles.
- Mineral particles with high specific gravity are less susceptible to rising water currents. It is discharged from the bottom of the device.
- the beneficiation efficiency is controlled by adjusting the feed size and the amount of rising water flow.
- WHIMS is a method of mineral beneficiation with a magnetic force of 8000-12000 gauss or more. Disposed within the device is a rotating rotor and magnets disposed within the rotor. When a slurry (a mixture of water and mineral particles) is fed into the device, the non-magnetic particles are not attracted to the magnet, so they fall and are collected in a fixed tray at the bottom of the rotation. Paramagnetic particles are captured by a high magnetic force and high gradient magnetic field, and ejected at the point where the magnetism weakens as the rotor rotates. Ferromagnetic particles travel with the rotation of the rotor and are expelled away from the magnetic field.
- a slurry a mixture of water and mineral particles
- Heavy liquid sorting is a type of gravity beneficiation process. Heavy liquid sorting is also called heavy liquid ore beneficiation, heavy liquid coal beneficiation, floating/sink sorting, and the like. Heavy liquid sorting is a method of separating useful minerals and waste rocks using a liquid with a large specific gravity (heavy liquid) as a medium. Heavy liquid materials (magnetite, slag, barite, etc.), which have a specific gravity two to three times that of the heavy liquid to be produced, are hard and difficult to miniaturize, have good chemical stability, and are easy to purify and collect, are pulverized into water. to obtain a heavy liquid. Mineral particles having a higher specific gravity than the heavy liquid sink in the heavy liquid, and mineral particles having a lower specific gravity float on the upper surface of the heavy liquid, thereby separating mineral particles having a desired specific gravity.
- Heavy liquid sorting is a type of gravity beneficiation process. Heavy liquid sorting is also called heavy liquid ore beneficiation, heavy liquid coal beneficiation, floating/sink sorting, and the
- the iron ore raw material (highly crystalline water iron ore) is at least hematite-rich with an ignition loss LOI of less than 4% by mass and an iron content of 55% by mass or more. and a goethite-rich portion having an ignition loss LOI of 4% by mass or more and an iron content of 55% by mass or more.
- An iron ore feedstock can be separated into a hematite-rich fraction, a goethite-rich fraction, and a gangue-rich fraction.
- Table 3 shows an example of the results of gravity separation of iron ore raw materials (high crystalline water iron ore) by UCC.
- the UCC can separate the iron ore raw material into a hematite-rich portion, a goethite-rich portion, and a gangue-rich portion.
- the goethite-rich portion and the hematite-rich portion are separately agglomerated using a pellet firing furnace to obtain raw materials for direct reduction.
- the hematite-rich portion is agglomerated using a pellet firing furnace.
- the goethite-rich portion is agglomerated using a pellet firing furnace.
- a specific method of the pellet manufacturing process is not particularly limited, and may be performed according to a general pellet manufacturing method.
- An example of the pellet manufacturing process is described in Non-Patent Document 3 (KOBE STEEL ENGINEERING REPORTS/Vol. 60 No. 1 (Apr. 2010).
- the pellet manufacturing process is performed by the method described in the document.
- the manufacturing method is not limited to the method described in this non-patent document.
- Table 4 shows an example of the composition of each pellet. Since the fired pellets derived from the hematite-rich portion (second fired pellets) have a low gangue content, they can be directly reduced and used as raw materials for electric furnaces. The fired pellets derived from the goethite-rich portion (first fired pellets) have a relatively high gangue content and are not suitable as raw materials for electric furnaces, so they can be used as raw materials for blast furnaces. Goethite-rich pellets in Table 4 mean the first fired pellets, and hematite-rich pellets mean the second fired pellets.
- the goethite-rich portion may be agglomerated using a sintering machine and used as a raw material for a blast furnace, instead of the above-described pellet manufacturing step.
- the conditions for producing sintered ore are not particularly limited. Fired pellets derived from the goethite-rich portion may have problems of strength and reduction pulverizability during reduction. Agglomeration as sintered ore can avoid the problem.
- the gangue-rich portion is preferably discarded or agglomerated as sintered ore in a sintering machine, depending on its iron content.
- the reduction method S20 includes a first reduction step S5B.
- the reduction method S20 may include a blast furnace step S6.
- a reduction method S20A for further reducing the fired pellets derived from the hematite-rich portion includes a first reduction step S5B and a second reduction step S5A.
- the fired pellets derived from the hematite-rich portion (second fired pellets) are directly reduced using a shaft furnace to obtain direct reduced iron having a metallization rate of 90% or more.
- the obtained direct reduced iron can be used as a reduced iron raw material for an electric furnace.
- the reducing gas As the reducing gas, natural gas, synthetic gas (Syn-gas), H 2 gas, etc. can be used.
- the reducing gas preferably contains 60% by volume or more of hydrogen gas.
- the operating conditions of the shaft furnace are, for example, as follows.
- molten steel is obtained using the reduced iron for electric furnace obtained in the second reduction step S5A.
- ⁇ Reducing gas temperature 700-1000°C ⁇ Reducing gas flow rate 1000 to 2200 Nm 3 /t-DRI (flow rate per ton of reduced iron) - Metallization rate: 90% or more
- the metallization rate is defined as metallic iron concentration/total iron concentration x 100.
- the method for measuring the concentration of metallic iron is specified in ISO 5416 Bromine-methanol titration method for measuring metallic iron in reduced iron.
- the total iron concentration is specified in JIS M 8212: 2005 Iron Ore-Total Iron Determination Method.
- the fired pellets derived from the goethite-rich portion are charged into a shaft furnace at a surface temperature of the first fired pellets of 600 ° C. or higher, and a reducing gas containing 60% by volume or more of hydrogen.
- a surface temperature of the first fired pellet is not particularly limited, and is 800° C., for example.
- the first fired pellet may be directly reduced to a semi-reduced state with a metallization rate of 60 to 95% to obtain a semi-reduced fired pellet.
- a more preferred degree of metallization after direct reduction is 60-90%.
- a semi-reduced state means a state with a metallization rate of 60 to 95%.
- the obtained semi-reduced fired pellets can be used as raw materials for blast furnaces if the metallization rate is high.
- a semi-reduced calcined pellet refers to a calcined pellet with a metallization rate of 60% to 95%.
- the reducing gas natural gas, synthetic gas (Syn-gas), H 2 gas, etc. can be used.
- the reducing gas preferably contains 60% by volume or more of hydrogen gas.
- the operating conditions of the shaft furnace are, for example, as follows.
- the upper limit of hydrogen gas is not particularly limited, and is, for example, 100% by volume.
- the temperature of the sintered pellets (first sintered pellets) derived from the goethite-rich portion when charged into the shaft furnace is less than 600° C.
- the first sintered pellets are pulverized in the shaft furnace, and the shaft Raw material clogs in the furnace, resulting in poor discharge. Therefore, the temperature of the first fired pellets when charged into the shaft furnace is 600° C. or higher.
- the temperature of the first fired pellets when charged into the shaft furnace is preferably 650° C. or higher. Since the gangue-rich portion is agglomerated as sintered ore as described above, it is preferably used as a raw material for a blast furnace.
- the highly crystalline water iron ore is beneficiated into a hematite-rich portion, a goethite-rich portion, and a gangue-rich portion, and is reduced by a method suitable for each. Therefore, it is possible to efficiently reduce an iron ore raw material of inferior quality.
- Dust recycling The dust and DRI powder generated from the direct reduction ironmaking process should be treated in the same route as the goethite-rich zone. Dust and DRI powder have the effect of improving the strength of pellets, and when used in goethite-rich pellets with low strength, strength can be improved.
- the blast furnace step S6 of the hematite-rich portion or goethite-rich portion that has been beneficiated in the beneficiation treatment step, a portion having a grain size that can be used as lump ore in the blast furnace may be directly used in the blast furnace, or the goethite-rich portion may be used directly in the blast furnace.
- the resulting calcined pellets may be charged directly into the blast furnace.
- Pig iron can be obtained in the blast furnace step S6.
- steel can be obtained from the pig iron obtained in the blast furnace step S6.
- Example 1 sintered pellets derived from the goethite-rich portion having the composition shown in Table 4 were charged into a shaft furnace to produce semi-reduced iron. Natural gas or synthetic gas was used as reducing gas.
- the manufacturing conditions are as follows.
- the raw material temperature is the temperature of the sintered pellets when charged into the shaft furnace.
- Raw material used fired pellets derived from the goethite-rich part described in Table 4 above ⁇ Raw material temperature 650 ° C ⁇ Reducing gas temperature 950°C ⁇ Reducing gas flow rate 1200 Nm 3 /t-DRI ⁇ Metallization rate 82% ⁇ Use of products Composition of semi-reduced iron and reducing gas for blast furnace is the temperature (°C) of the input gas (Inlet) or the output gas (Outlet).)
- semi-reduced iron with a metallization rate of 82% could be produced.
- the semi-reduced iron derived from the goethite-rich portion contains many gangue components, and is therefore suitable as a raw material for blast furnaces.
- Example 2 sintered pellets derived from the hematite-rich portion having the composition shown in Table 4 were charged into a shaft furnace to produce reduced iron. Hydrogen gas was used as the reducing gas.
- the manufacturing conditions are as follows. ⁇ Materials used: Hematite-rich pellets listed in Table 4 above ⁇ Material temperature: 650°C ⁇ Reducing gas temperature 1020°C ⁇ Reducing gas flow rate 1400 Nm 3 /t-DRI ⁇ Metallization rate 94% ⁇ Use of products Composition of reduced iron and reducing gas for electric furnaces is the temperature (°C) of the input gas (Inlet) or the output gas (Outlet).)
- Example 2 it was possible to produce reduced iron with a metallization rate of 94%.
- the reduced iron derived from the hematite-rich portion contains few gangue components, and is therefore suitable as a raw material for electric furnaces.
- Example 3 sintered pellets derived from the goethite-rich portion having the composition shown in Table 4 were charged into a shaft furnace to produce semi-reduced iron. Hydrogen was used as the reducing gas.
- the manufacturing conditions are as follows. ⁇ Raw material used: fired pellets derived from the goethite-rich part described in Table 4 ⁇ Raw material temperature 600 ° C ⁇ Reducing gas temperature 1050°C ⁇ Reducing gas flow rate 1250 Nm 3 /t-DRI ⁇ Metallization rate 85% ⁇ Use of products Composition of semi-reduced iron and reducing gas for blast furnace is the temperature (°C) of the input gas (Inlet) or the output gas (Outlet).)
- semi-reduced iron with a metallization rate of 84% could be produced.
- the semi-reduced iron derived from the goethite-rich portion contains many gangue components, and is therefore suitable as a raw material for blast furnaces.
- Example 4 sintered pellets derived from the goethite-rich portion having the composition shown in Table 4 were charged into a shaft furnace to produce semi-reduced iron. Hydrogen was used as the reducing gas.
- the manufacturing conditions are as follows.
- Raw material used fired pellets derived from the goethite-rich part described in Table 4 ⁇ Raw material temperature 650 ° C ⁇ Reducing gas temperature 1020°C ⁇ Reducing gas flow rate 1580 Nm 3 /t-DRI ⁇ Metallization rate 92% ⁇ Use of products Composition of semi-reduced iron for blast furnace or reduced iron/reduced gas for electric furnace Volume % is shown.
- the column of Temp in Table 8 is the temperature of the input gas (Inlet) or the temperature (° C.) of the output gas (Outlet).
- semi-reduced iron with a metallization rate of 92% could be produced.
- the semi-reduced iron derived from the goethite-rich portion contains many gangue components, and is therefore suitable as a raw material for blast furnaces.
- the high metallization rate because of its high metallization rate, it can also be used as reduced iron for electric furnaces.
- Example 5 sintered pellets derived from the goethite-rich portion having the composition shown in Table 4 were charged into a shaft furnace to produce semi-reduced iron. Hydrogen was used as the reducing gas.
- the manufacturing conditions are as follows.
- Raw materials used fired pellets derived from the goethite-rich part described in Table 4 ⁇ Raw material temperature 620 ° C ⁇ Reducing gas temperature 980°C ⁇ Reducing gas flow rate 1700 Nm 3 /t-DRI ⁇ Metallization rate 95% ⁇ Use of products Composition of semi-reduced iron for blast furnace or reduced iron/reduced gas for electric furnace Volume % is shown.
- the column of Temp in Table 9 is the temperature of the input gas (Inlet) or the temperature (° C.) of the output gas (Outlet).
- semi-reduced iron with a metallization rate of 95% could be produced.
- the semi-reduced iron derived from the goethite-rich portion contains many gangue components, and is therefore suitable as a raw material for blast furnaces.
- the high metallization rate because of its high metallization rate, it can also be used as reduced iron for electric furnaces.
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Abstract
Description
(1)本発明の態様1の製鉄方法は、灼熱減量が3~12質量%である高結晶水鉄鉱石を少なくとも灼熱減量が4質量%以上、鉄分55質量%以上のゲーサイトリッチ部に選鉱する選鉱処理工程と、ゲーサイトリッチ部はペレット焼成炉で第1焼成ペレットに塊成化する、第1塊成化処理工程と、前記第1焼成ペレットを、前記第1焼成ペレットの表面温度600℃以上でシャフト炉に装入し、水素が60体積%以上の還元ガスを用いて直接還元する。
本発明の態様2は、態様1の製鉄方法において、前記第1焼成ペレットを金属化率60%~95%に直接還元してもよい。
文中、表中の鉄鉱石等の各成分の百分率(%)は、鉄鉱石等の総質量に対する質量%を意味する。ここに、鉄分の測定は、JIS M 8212: 2005 鉄鉱石-全鉄定量方法に準じる。また、灼熱減量(Loss of ignition:LOI)をもって結晶水含有量と見做す。灼熱減量(LOI)は、鉄鉱石を1000℃で60分間保持した際の質量減少割合とする。
本実施形態に係る塊成化方法および還元方法は、結晶水を多く含む鉄鉱石、例えば潤沢な埋蔵量を有する豪州産の含ゲーサイト鉄鉱石を活用した製鉄方法である。本実施形態に係る製鉄方法は、まず選鉱処理により、鉄鉱石原料をゲーサイト主体のゲーサイトリッチ部に分離する。選鉱処理では、ヘマタイト主体のヘマタイトリッチ部、ゲーサイト主体のゲーサイトリッチ部、脈石主体の脈石リッチ部に分離してもよい。ここで、ヘマタイトリッチ部は、LOIが4質量%未満鉄分55質量%以上となる部位であり、ゲーサイトリッチ部は、LOIが4質量%以上鉄分55質量%以上となる部位であり、脈石リッチ部は、鉄分55質量%未満の部位である。ヘマタイトリッチ部は、高結晶水鉄鉱石のうちヘマタイトが主体の部位であり、LOIが4質量%未満鉄分55質量%以上となる高結晶水鉄鉱石の部位をいう。なお、ヘマタイトが主体の部位とは、当該部位の全質量に対して、ヘマタイトの含有量が50質量%以上である部位をいう。また、ゲーサイトリッチ部は、高結晶水鉄鉱石のうちゲーサイトが主体の部位であり、LOIが4質量%以上鉄分55質量%以上となる高結晶水鉄鉱石の部位をいう。ゲーサイトが主体の部位とは、当該部位の全質量に対して、ゲーサイトの含有量が50質量%以上であることをいう。脈石リッチ部は、高結晶水鉄鉱石のうち脈石が主体となる部位であり、鉄分55質量%未満の高結晶水鉄鉱石の部位をいう。脈石が主体の部位とは、当該部位の全質量に対して、脈石の含有量が50質量%以上であることをいう。続いて、ヘマタイトリッチ部およびゲーサイトリッチ部を別々に塊成化および還元処理することで、ヘマタイトリッチ部を電気炉用の原料に、ゲーサイトリッチ部を高炉用の原料に加工する。
(2-1.処理対象の鉄鉱石)
つぎに、本実施形態に係る製鉄方法の詳細について説明する。本実施形態の処理対象となる鉄鉱石(鉄鉱石原料)は上述した高結晶水鉄鉱石である。高結晶水鉄鉱石は、結晶水を3~12質量%含む。ここでは、結晶水の質量%は、灼熱減量(LOI)として測定する。高結晶水鉄鉱石は鉄分を55~67質量%含むことが多い。高結晶水鉄鉱石の例として、表1に示す成分を有する豪州産鉄鉱石ブロックマン鉱が挙げられる。
図1に本実施形態に係る製鉄方法における、塊成化方法S10および還元方法S20の全体フローを示す。図2に本実施形態に係る製鉄方法における、別の塊成化方法S10Aおよび還元方法S20Aの全体フローを示す。塊成化方法S10は、水洗処理工程S1と、選鉱処理工程S2と、第1塊成化処理工程S3Bとを含む。塊成化方法S10は、さらに焼結鉱製造工程S4を含んでもよい。ヘマタイトリッチ部についても選鉱して塊成化する、塊成化方法S10Aは、水洗処理工程S1と、選鉱処理工程S2と、第1塊成化処理工程S3Bと第2塊成化処理工程S3Aと、を含む。
鉄鉱石原料である高結晶水鉄鉱石を、比重分離法を用いて複数に分離する。そして分離された部位を、ゲーサイトリッチ部を鉄分およびLOIから判別する。分離された部分をヘマタイトリッチ部、ゲーサイトリッチ部及び脈石リッチ部のいずれであるか鉄分およびLOIから判別してもよい。ここで、ヘマタイトリッチ部は、LOIが4質量%未満鉄分55質量%以上となる部位であり、ゲーサイトリッチ部は、LOIが4質量%以上鉄分55質量%以上となる部位であり、脈石リッチ部は、鉄分55質量%未満の部位である。
分離されたゲーサイトリッチ部は図1の流れに従って、塊成化処理する。分離された各部は、それぞれ、図2の流れにそって別々に塊成化処理してもよい。第2塊成化処理工程S3Aにおいて、ヘマタイトリッチ部をペレット焼成炉で、第2焼成ペレットに塊成化する。第1塊成化処理工程S3Bにおいて、ゲーサイトリッチ部は、ペレット焼成炉で第1焼成ペレットに塊成化する。なお、ゲーサイトリッチ部を焼結機で焼結鉱にしてもよい。脈石リッチ部は、その鉄分含有量に応じて、廃棄又は焼結鉱用原料とするのがよい。
水洗処理工程S1において、選鉱処理に先立って鉄鉱石原料の水洗処理を行うことが好ましい。水洗処理によって、高結晶水鉄鉱石から粘土鉱物(尾鉱)を除去することができる。具体的には、例えば、鉄鉱石原料をドラム式スクラバーまたは水洗篩等で水洗する。これにより、鉄鉱石原料の表面に付着する粒度20~45μm以下の粘土鉱物(所謂尾鉱)を洗い流すことができる。尾鉱は鉄分が低いので廃棄するのがよい。
ついで、選鉱処理工程S2において、水洗された鉄鉱石原料を選鉱処理して複数の部位に分離する。選鉱処理工程S2において、高結晶水鉄鉱石を少なくとも鉄分55質量%以上のゲーサイトリッチ部に選鉱する。選鉱処理工程S2において、高結晶水鉄鉱石を灼熱減量LOIが4質量%未満、鉄分55質量%以上のヘマタイトリッチ部と、灼熱減量LOIが4質量%以上、鉄分55質量%以上のゲーサイトリッチ部と、に選鉱してもよい。選鉱処理工程S2において、高結晶水鉄鉱石を鉄分55質量%未満の脈石リッチ部にさらに選鉱してもよい。そして、分離された各部位のLOIおよび鉄分を分析して、ヘマタイトリッチ部、ゲーサイトリッチ部及び脈石リッチ部のいずれに属するかを判別する。ここで、各鉱物相の比重は、ヘマタイト:5.3g/cm3、ゲーサイト:3.8g/cm3、脈石:2.7g/cm3であるので、所謂比重選鉱処理(比重分離処理)により鉄鉱石原料をヘマタイトリッチ部、ゲーサイトリッチ部、及び脈石リッチ部に分離することができる。比重選鉱とともに磁力選鉱を行ってもよい。
篩上:JIGまたは重液選別
篩下:スパイラル、Up-current classifiers (UCC)、Wet High Intensity Magnetic Separation(WHIMS)または重液選別
分級粒度を3mmとする理由は、JIGで効率的に選鉱できる粒度範囲が3.0mm以上であり、スパイラルで効率的に分級できる粒度範囲が3.0mm以下であるためである。以下、各選鉱処理方法の概要について説明する。
JIGは、比重選鉱処理の一種であり、鉱物粒子を比重の差を利用して選別する方法である。鉱物粒子は網を底とした粒子層に供給される。次に水を断続的に下から上へと流し水位を上昇させる。これにより鉱物粒子は水中へ巻き上げられ、一時的に浮遊する。続いて水の流れを止める。これにより、水位が下って元に戻る中で、鉱物粒子は網の上に再度沈降する。水中に浮遊して再び網の上に沈降するとき、鉱物粒子の比重が大きいほど当該鉱物粒子は速く落下するため、沈降後の粒子層では下側により比重の大きな鉱物粒子が集まる。こうすることで鉱物粒子を比重により濃縮させることができる。すなわち、形成された各粒子層から所望の鉱物粒子を抜き出すことで、比重により鉱物粒子を選別することができる。
スパイラルは、比重選鉱処理の一種であり、スパイラル(螺旋)状の樋中を流れるスラリー(水と鉱物粒子の混合物)に生じる遠心力を利用した選鉱方法である。塔の上からスラリーを流すとスラリーが螺旋を下る間に比重が小さい鉱物粒子は遠心力で外側に集まり他の鉱物粒子と分離することができる。遠心力の影響をより受けにくい高比重な鉱物粒子は樋の内周に集まり、抜き取られる。給鉱サイズおよび樋内の水量調整により選鉱効率が制御される。
UCCも比重選鉱処理の一種である。UCCでは、装置上部からスラリー(水と鉱物粒子の混合物)が供給され、下部から上昇水流が供給される。そして、装置内でこれらが交流して接触し、比重が小さい鉱物粒子は上昇水流に乗るので、他の鉱物粒子と分離することができる。高比重な鉱物粒子は上昇水流の影響を受けにくく。装置下部より排出される。給鉱サイズおよび上昇水流の水量調整により選鉱効率が制御される。
WHIMSは8000~12000ガウス以上の磁力による選鉱方法である。装置内には、回転するローターと、ローター内に配置された磁石とが配置されている。スラリー(水と鉱物粒子の混合物)が装置に給鉱されると、非磁性体粒子は磁石につかないため、そのまま落下して回転下部の固定トレイに集められる。常磁性体粒子は高磁力・高勾配磁界で補足され、ローター回転に乗って磁性が弱くなった箇所で排出される。強磁性体粒子はローターの回転に乗って移動し、磁界から外れた場所で排出される。
重液選別は、比重選鉱処理の一種である。重液選別は、重液選鉱、重液選炭、浮沈選別などとも称される。重液選別は、比重の大きい液(重液)を媒質として有用鉱物と廃石などの分離を行う方法である。作出する重液の2~3倍の比重をもち、硬く微細化しにくく、化学的安定性が良好で浄化回収が容易な重液材料(磁鉄鉱、鉱滓、重晶石など)を微粉砕して水に懸濁させて重液が得られる。重液よりも高比重な鉱物粒子は重液に沈み、低比重な鉱物粒子は重液の上面に浮き上がることにより、所望の比重の鉱物粒子が分離される。
ついで、ペレット製造工程において、ゲーサイトリッチ部とヘマタイトリッチ部とを別々にペレット焼成炉を用いて塊成化し、直接還元用原料とする。第2塊成化処理工程S3Aにおいて、ペレット焼成炉を用いて、ヘマタイトリッチ部を塊成化する。第1塊成化処理工程S3Bにおいて、ペレット焼成炉を用いて、ゲーサイトリッチ部を塊成化する。ペレット製造工程の具体的な方法は特に制限されず、一般的なペレット製造方法に従って行えばよい。ペレット製造工程の例は、非特許文献3(KOBE STEEL ENGINEERING REPORTS/Vol. 60 No. 1(Apr. 2010)に記載されている。本実施形態では、当該文献に記載された方法でペレット製造工程を行うものとするが、製造方法はこの非特許文献に記載の方法に限定されない。
焼結鉱製造工程S4において、ゲーサイトリッチ部は、前述のペレット製造工程に代えて、焼結機を用いて塊成化し、高炉用原料としてもよい。ここに、焼結鉱製造に際する条件は特に限定されない。ゲーサイトリッチ部由来の焼成ペレットは、還元時に強度及び還元粉化性が問題となる場合がある。焼結鉱として塊成化するとその問題を回避できる。
脈石リッチ部は、その鉄分含有量に応じて、廃棄又は焼結機で焼結鉱として塊成化することが好ましい。
図1の右側に還元工程のフロー図を示す。還元方法S20は、第1還元工程S5Bを含む。還元方法S20は、高炉工程S6を含んでもよい。ヘマタイトリッチ部由来の焼成ペレットをさらに還元する、還元方法S20Aは、第1還元工程S5Bと、第2還元工程S5Aと、を含む。
第2還元工程S5Aでは、ヘマタイトリッチ部由来の焼成ペレット(第2焼成ペレット)を、シャフト炉を用いて直接還元し、金属化率90%以上の直接還元鉄とする。得られた直接還元鉄を電気炉用の還元鉄原料とすることができる。還元ガスとしては、天然ガス、合成ガス(Syn-gas)、H2ガス等を使用することができる。還元ガスは、水素ガスを60体積%以上含むことが好ましい。シャフト炉の操業条件は例えば以下の通りである。電気炉工程S7において、第2還元工程S5Aで得られた電気炉用の還元鉄を用いて、溶鋼を得る。
・還元ガス温度 700~1000℃
・還元ガス流量 1000~2200 Nm3/t-DRI(還元鉄1トン当たりの流量)
・金属化率 90%以上
ここで、金属化率は、金属鉄濃度/全鉄分濃度×100で定義される。金属鉄濃度の測定方法はISO 5416 還元鉄中の金属鉄を測定する臭素メタノール滴定法に規定されている。全鉄分濃度はJIS M 8212: 2005 鉄鉱石-全鉄定量方法に規定されている。
・還元ガス温度 700~1000℃
・還元ガス流量 1000~2200 Nm3/t-DRI(還元鉄1トン当たりの流量)
・金属化率 60%~95%
ここで、シャフト炉に装入する際のゲーサイトリッチ部由来の焼成ペレット(第1焼成ペレット)の温度が600℃未満となっている場合、シャフト炉内で第1焼成ペレットが粉化し、シャフト炉内で原料が閉塞し、排出不良となる。そのため、シャフト炉内に装入する際の第1焼成ペレットの温度は600℃以上である。シャフト炉内に装入する際の第1焼成ペレットの温度は650℃以上であることが好ましい。
脈石リッチ部は上述した通り焼結鉱として塊成化されているので、高炉用の原料として使用することが好ましい。
直接還元による製鉄方法から発生するダストやDRI粉は、ゲーサイトリッチ部に合わせて、それと同じルートで処理するのがよい。ダストやDRI粉はペレットの強度を向上させる効果があり、強度が低いゲーサイトリッチペレットに使用すると強度を改善することができる。
高炉工程S6において、選鉱処理工程で選鉱されたヘマタイトリッチ部又はゲーサイトリッチ部の内、高炉で塊鉱として使用可能な粒度を有する部分を高炉に直接使用してもよいし、ゲーサイトリッチ部由来の焼成ペレットを直接高炉に装入してもよい。高炉工程S6において、銑鉄を得ることができる。転炉工程S8において、高炉工程S6で得られた銑鉄から鋼を得ることができる。
実施例1では、表4に示す組成のゲーサイトリッチ部由来の焼成ペレットをシャフト炉に装入し、半還元鉄を製造した。還元ガスとして天然ガスまたは合成ガスを使用した。製造条件は以下の通りである。原料温度は、シャフト炉に装入する際の焼成ペレットの温度である。
・使用原料:前述の表4に記載のゲーサイトリッチ部由来の焼成ペレット
・原料温度 650℃
・還元ガス温度 950℃
・還元ガス流量 1200Nm3/t-DRI
・金属化率 82%
・生産物の用途 高炉用半還元鉄
・還元ガスの組成 表5に示す通り(Inletは入力ガス、Outletは出力ガス(排ガス)の組成を示す。各成分の数値は体積%を示す。表5に記載のTempの欄は、入力ガス(Inlet)の温度または出力ガス(Outlet)の温度(℃)である。)
実施例2では、表4に示す組成のヘマタイトリッチ部由来の焼成ペレットをシャフト炉に装入し、還元鉄を製造した。還元ガスとして水素ガスを使用した。製造条件は以下の通りである。
・使用原料 前述の表4に記載のヘマタイトリッチペレット
・原料温度 650℃
・還元ガス温度 1020℃
・還元ガス流量 1400 Nm3/t-DRI
・金属化率 94%
・生産物の用途 電気炉用還元鉄
・還元ガスの組成 表6に示す通り(Inletは入力ガス、Outletは出力ガス(排ガス)の組成を示す。各成分の数値は体積%を示す。表6に記載のTempの欄は、入力ガス(Inlet)の温度または出力ガス(Outlet)の温度(℃)である。)
実施例3では、表4に示す組成のゲーサイトリッチ部由来の焼成ペレットをシャフト炉に装入し、半還元鉄を製造した。還元ガスとして水素を使用した。製造条件は以下の通りである。
・使用原料:表4に記載のゲーサイトリッチ部由来の焼成ペレット
・原料温度 600℃
・還元ガス温度 1050℃
・還元ガス流量 1250Nm3/t-DRI
・金属化率 85%
・生産物の用途 高炉用半還元鉄
・還元ガスの組成 表7に示す通り(Inletは入力ガス、Outletは出力ガス(排ガス)の組成を示す。各成分の数値は体積%を示す。表7に記載のTempの欄は、入力ガス(Inlet)の温度または出力ガス(Outlet)の温度(℃)である。)
実施例4では、表4に示す組成のゲーサイトリッチ部由来の焼成ペレットをシャフト炉に装入し、半還元鉄を製造した。還元ガスとして水素を使用した。製造条件は以下の通りである。
・使用原料:表4に記載のゲーサイトリッチ部由来の焼成ペレット
・原料温度 650℃
・還元ガス温度 1020℃
・還元ガス流量 1580Nm3/t-DRI
・金属化率 92%
・生産物の用途 高炉用半還元鉄、または電気炉用還元鉄
・還元ガスの組成 表8に示す通り(Inletは入力ガス、Outletは出力ガス(排ガス)の組成を示す。各成分の数値は体積%を示す。表8に記載のTempの欄は、入力ガス(Inlet)の温度または出力ガス(Outlet)の温度(℃)である。)
実施例5では、表4に示す組成のゲーサイトリッチ部由来の焼成ペレットをシャフト炉に装入し、半還元鉄を製造した。還元ガスとして水素を使用した。製造条件は以下の通りである。
・使用原料:表4に記載のゲーサイトリッチ部由来の焼成ペレット
・原料温度 620℃
・還元ガス温度 980℃
・還元ガス流量 1700Nm3/t-DRI
・金属化率 95%
・生産物の用途 高炉用半還元鉄、または電気炉用還元鉄
・還元ガスの組成 表9に示す通り(Inletは入力ガス、Outletは出力ガス(排ガス)の組成を示す。各成分の数値は体積%を示す。表9に記載のTempの欄は、入力ガス(Inlet)の温度または出力ガス(Outlet)の温度(℃)である。)
Claims (5)
- 灼熱減量が3~12質量%である高結晶水鉄鉱石を少なくとも灼熱減量が4質量%以上、鉄分55質量%以上のゲーサイトリッチ部に選鉱する選鉱処理工程と、
前記ゲーサイトリッチ部をペレット焼成炉で第1焼成ペレットに塊成化する、第1塊成化処理工程と、
前記第1焼成ペレットを、前記第1焼成ペレットの表面温度600℃以上でシャフト炉に装入し、水素が60体積%以上の還元ガスを用いて直接還元する、第1還元工程と、
を有することを特徴とする、製鉄方法。 - 前記第1還元工程において、前記第1焼成ペレットを金属化率60%~95%に直接還元することを特徴とする、請求項1に記載の製鉄方法。
- 前記選鉱処理工程において、灼熱減量が4質量%未満、鉄分55質量%以上のヘマタイトリッチ部をさらに選鉱し、
前記ヘマタイトリッチ部をペレット焼成炉で第2焼成ペレットに塊成化する、第2塊成化処理工程をさらに有する、ことを特徴とする請求項1に記載の製鉄方法。 - 前記第2焼成ペレットを、シャフト炉で水素が60体積%以上の還元ガスを用いて直接還元して金属化率90%以上の直接還元鉄とする、第2還元工程をさらに有する、ことを特徴とする請求項3に記載の製鉄方法。
- 前記選鉱処理工程の前に、前記高結晶水鉄鉱石から尾鉱を除去する水洗処理工程をさらに有することを特徴とすることを特徴とする請求項1~4のいずれか1項に記載の製鉄方法。
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