EP4549601A1 - Nicht gebrannte pellets zur reduktion und verfahren zur herstellung davon - Google Patents

Nicht gebrannte pellets zur reduktion und verfahren zur herstellung davon Download PDF

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Publication number
EP4549601A1
EP4549601A1 EP22953913.5A EP22953913A EP4549601A1 EP 4549601 A1 EP4549601 A1 EP 4549601A1 EP 22953913 A EP22953913 A EP 22953913A EP 4549601 A1 EP4549601 A1 EP 4549601A1
Authority
EP
European Patent Office
Prior art keywords
fired pellets
mass
reduction
mgo
sio
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22953913.5A
Other languages
English (en)
French (fr)
Other versions
EP4549601A4 (de
Inventor
Kenta Takehara
Tetsuya Yamamoto
Takahide Higuchi
Yuji Iwami
Shohei Fujiwara
Yuya Morita
Kenya HORITA
Toshiyuki Hirosawa
Daisuke Igawa
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
JFE Steel Corp
Original Assignee
JFE Steel Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by JFE Steel Corp filed Critical JFE Steel Corp
Publication of EP4549601A1 publication Critical patent/EP4549601A1/de
Publication of EP4549601A4 publication Critical patent/EP4549601A4/de
Pending legal-status Critical Current

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    • 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
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/0086—Conditioning, transformation of reduced iron ores
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/0046—Making spongy iron or liquid steel, by direct processes making metallised agglomerates or iron oxide
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/008—Use of special additives or fluxing agents
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/10—Making spongy iron or liquid steel, by direct processes in hearth-type furnaces
    • C21B13/105—Rotary hearth-type 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
    • C22B1/24—Binding; Briquetting ; Granulating
    • C22B1/2406—Binding; Briquetting ; Granulating pelletizing

Definitions

  • the present invention relates to fired pellets for reduction that can be effectively used in a solid reduction furnace, and a method for producing the same.
  • Patent Literature 1 proposes a method for covering the surfaces of pellets with, for example, Ca(OH) 2 or Mg(OH) 2 .
  • Patent Literature 2 proposes a method for preventing reduction-degradation and obtaining a fired pellet with fewer blisters by covering the surface of sintered agglomerated ore (pellet) with a powdery solid fuel.
  • Patent Literature 3 is directed to prevent the occurrence of clustering in a solid reduction furnace as well as reduce heat loss and improve the operation efficiency by covering the surface of a fired pellet with iron ore mixed with cement.
  • Patent Literature 4 proposes a method for performing covering with a material containing a calcium-iron compound represented by CaxFeyOz (1 ⁇ y/x ⁇ 2; 1 ⁇ z).
  • Patent Literatures 1 to 4 are a method for reducing the contact between metallic irons after reduction, which can cause clustering observed around a high-temperature zone (500 to 600°C) in a solid reduction furnace, such as a shaft furnace, by mainly interposing non-metallic components therebetween.
  • clustering prevention methods of the conventional technologies are insufficient. These methods have a problem in that it also requires to adapt a covering step of non-metallic components, which increases the cost, and the addition of a dedicated facility.
  • an object of the present invention is to propose, in producing fired pellets for use in a solid reduction furnace, fired pellets that is effective in preventing clustering by reducing the possibility of contact between low-melting-temperature slags and thus preventing the fusion between the slags, and a method for producing such fired pellets.
  • the present invention relates to a method that can solve the above problems of the conventional technologies and has been developed to achieve the above object.
  • the present invention proposes fired pellets for reduction characterized in that a ratio of high-viscosity slag components (Al 2 O 3 +MgO+SiO 2 ) to total Fe (T.Fe) satisfies the following Expression (1): Al 2 O 3 + MgO + SiO 2 / T . Fe ⁇ 0.09
  • the present invention proposes a method for producing the above fired pellets for reduction, comprising performing reduction and firing by using an iron-containing raw material formulated to achieve an average LOI (Loss on Ignition) of 5% or more.
  • LOI Loss on Ignition
  • fired pellets for reduction of the present invention may include the following feature that is considered to be able to provide a more preferable embodiment.
  • the production of the fired pellets for reduction may include the following feature that is considered to be able to provide a more preferable embodiment.
  • the fired pellets for reduction of the present invention contain high-viscosity slag components (Al 2 O 3 , MgO, and SiO 2 ) at a high proportion relative to the total iron can reduce the generation of low-melting-temperature slag due to FeO during reduction in a solid reduction furnace and its fluidity. Consequently, it is possible to prevent the possibility of contact or fusion between the pellets due to such interposed slag and thus effectively prevent the above-described clustering in the reduction furnace that is a problem to be solved.
  • high-viscosity slag components Al 2 O 3 , MgO, and SiO 2
  • the production method according to the present invention involves the use of a high-LOI raw material formulated as an iron-containing raw material, causing the obtained fired pellets to be porous.
  • a high-LOI raw material formulated as an iron-containing raw material
  • the possibility of contact between the metallic irons is reduced, thereby effectively preventing clustering and increasing the operation efficiency of a solid reduction furnace.
  • Fig. 1 is a graph illustrating the relationship between (Al 2 O 3 +MgO+SiO 2 )/T.Fe and LOI of Australian iron ore that is an iron-containing raw material to be mixed.
  • a solid reduction furnace used in the present invention is a furnace for reducing fed fired pellets for reduction to Fe having a reduction degree of 90% or more by using a hydrogen gas, etc., as a reducing gas.
  • a hydrogen gas etc.
  • the properties of raw material fed into the furnace, that is, the fired pellets are important.
  • the fired pellets for reduction have a component composition such that the high-viscosity slag components (Al 2 O 3 +MgO+SiO 2 ) are contained in a given ratio relative to the total iron (T.Fe) in the iron-containing raw material. That is, when the fired pellets satisfy the relationship of Expression (1) below. Al 2 O 3 + MgO + SiO 2 / T . Fe ⁇ 0.09
  • Al 2 O 3 represents the concentration (mass%) of Al 2 O 3 in the fired pellets for reduction.
  • MgO represents the concentration (mass%) of MgO in the fired pellets for reduction.
  • SiO 2 represents the concentration (mass%) of SiO 2 in the fired pellets for reduction.
  • T.Fe represents the total Fe concentration (mass%) in the fired pellets for reduction.
  • Al 2 O 3 represents the concentration (mass%) of Al 2 O 3 in the fired pellets for reduction.
  • MgO represents the concentration (mass%) of MgO in thefired pellets for reduction.
  • SiO 2 represents the concentration (mass%) of SiO 2 in the fired pellets for reduction.
  • T.Fe represents the total Fe concentration (mass%) in the fired pellets for reduction.
  • the total Fe in the iron-containing raw material refers to the total value of the iron concentrations including the concentrations of metallic iron (M.Fe) and iron compounds (iron oxide, iron sulfide, calcium ferrite, etc.).
  • the high-viscosity slag components refer to the total value of the concentrations of Al 2 O 3 , MgO, and SiO 2 contained in the iron-containing raw material, such as iron ore or ironmaking dust; an auxiliary material (limestone, quicklime, dolomite, etc.); and a binder (bentonite, etc.).
  • the porosity of the fired pellets for reduction is also critical to control the porosity of the fired pellets for reduction according to the present invention, That is, when the fired pellets for reduction are made porous (20% or more, preferably 30% or more), the number of contact points between the pellets can be reduced, which can also reduce the contact between metallic irons and prevent fusion, thereby contributing to the prevention of the clustering described above. In this respect, a porosity of less than 20% is not effective in preventing fusion.
  • the upper limit is approximately 60% from the viewpoint of strength.
  • the method for producing the fired pellets according to the present invention will be described.
  • the fired pellets for reduction according to the present invention in order for the fired pellets to satisfy the above relationship between the high-viscosity slag components (Al 2 O 3 +MgO+SiO 2 ) and the total iron (T.Fe), for example, it is possible to use an iron ore originally having a composition of components satisfying the above relationship, or to selectively use and mix a plurality of iron ores to satisfy the above relationship.
  • iron ores brands
  • a binder such as bentonite
  • an auxiliary material such as quicklime
  • the iron-containing raw material for the iron-containing raw material to achieve the relation LOI ⁇ 5%, it is preferable to apply a pretreatment such as a process for removing crystal water to the iron ore to be used in advance so as to achieve LOI ⁇ 2%. Since many iron-containing raw materials such as raw material iron ore have a high crystal water content, pellets often burst during granulation due to water vapor generated from the crystal water. Thus, it would be unavoidable to increase the temperature slowly. This would reduce productivity.
  • a pretreatment such as a process for removing crystal water
  • the pretreatment such as a process for removing crystal water
  • the Examples show how the relationship between T.Fe and high-viscosity slag components (Al 2 O 3 +MgO+SiO 2 ) in fired pellets for reduction affects the clustering in a solid reduction furnace.
  • iron-containing raw material i.e. iron ore used herein, mainly one or more types of Australian iron ores (A to Z) shown in Fig.1 were mixed with an auxiliary material and reagent (e.g., commercially available Al 2 O 3 reagent) as appropriate.
  • auxiliary material and reagent e.g., commercially available Al 2 O 3 reagent
  • All raw materials including one or more types of the Australian raw materials described above (exemplified in Fig. 1 ) (A to Z) were ground in a ball mill and then granulated with a pelletizer while adding water to achieve a size of 9 to 16 mm. Then, the pellets after granulation were placed in a dryer to perform drying treatment at 110 °C for 24hr. The pellets were then fed into an electric furnace to be heated at 7 °C/min., held at 1250 °C for 10hr, and then cooled at 7 °C/min. Each of the fired pellets obtained, shown in Table 1, was evaluated using a porosity and a clustering index.
  • a sample weighing 500g was fed into a vertical cylindrical furnace with a diameter ⁇ of 100 mm and heated to 1000°C in an N 2 atmosphere.
  • a reducing gas was introduced into the furnace at a rate of 24 NL/min.
  • the sample was then loaded at a rate of 1 kg/cm 2 and held in this state for three hours, followed by cooling in an N 2 atmosphere, so that reduced iron was produced.
  • the reduced iron obtained was then sieved through a 16 mm sieve mesh, which is the maximum size of a single fired pellet, to measure the weight Wa (g) of the fired pellets remaining on the sieve.
  • the fired pellets remaining on the sieve were put into a cylindrical shape vessel (132 mm ⁇ ⁇ 700 mmL) of an I-type testing machine and were rotated at a rotational speed of 30 rpm for five minutes, to measure the weight Wb (g) of the fired pellets remaining on the sieve mesh of 16 mm.
  • the fired pellets were evaluated based on a clustering index that is proportional to the non-crushing clustering proportion Wb/Wa.
  • the porosity of the fired pellets was evaluated by measuring the apparent density of the pellets and then measuring the real density of the pellets. As shown in Table 1, it is confirmed that each of the fired pellets of Examples 1 to 5 in which (Al 2 O 3 +MgO+SiO 2 )/T.Fe is 0.09 or more has a clustering index of less than 7, and thus has excellent properties.
  • Table 2 shows the component compositions of the fired pellets obtained in Examples 1 and 2 of Table 1.
  • [Table 2] (mass%) T.Fe FeO SiO 2 CaO Al 2 O 3 MgO C/S Example 1 64.9 0.2 3.1 1.2 2.7 0.2 0.4 Example 2 62.5 0.4 4.9 2.9 2.3 0.3 0.6
  • Example 5 An evaluation test was conducted to determine whether granulation and firing can be achieved without breakage during granulation, by subjecting the sample in Example 5, shown in Table 1, to a crystal water removal pretreatment. It should be noted that the heating rate was set at 200°C/min.
  • Reduced iron (a sample when Wa was measured) obtained by the same method as the method of Comparative Example 2 in Embodiment 1 (clustering evaluation test) was ground into particles with a size of 3 mm or less. The resulting particles were mixed with the unfired raw material of Comparative Example 2. The mixture was used to produce fired pellets by the method of Embodiment 1. The crushing strength of the resulting fired pellets was then measured. The measurement results are shown in Table 4.
  • M.Fe is derived from metallic iron (M.Fe) contained in the reduced iron.
  • the unit “L” of volume represents 10 -3 m 3 .
  • Symbol “N” added to the unit of the volume of a gas represents the volume of the gas in the standard state, that is, at a temperature of 0°C and a pressure of 101325 Pa.
  • the unit “rpm” of a rotational speed represents the number of rotations per min.
  • the fired pellets for solid reduction according to the present invention are the method that has been developed to be mainly applied to a hydrogen-based direct reduction process, for example.
  • such fired pellets can also be used as a raw material for use in a blast furnace, etc.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Metallurgy (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)
EP22953913.5A 2022-08-01 2022-08-01 Nicht gebrannte pellets zur reduktion und verfahren zur herstellung davon Pending EP4549601A4 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2022/029423 WO2024028922A1 (ja) 2022-08-01 2022-08-01 還元用焼成ペレットとその製造方法

Publications (2)

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EP4549601A1 true EP4549601A1 (de) 2025-05-07
EP4549601A4 EP4549601A4 (de) 2025-12-17

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EP22953913.5A Pending EP4549601A4 (de) 2022-08-01 2022-08-01 Nicht gebrannte pellets zur reduktion und verfahren zur herstellung davon

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US (1) US20260028688A1 (de)
EP (1) EP4549601A4 (de)
CN (1) CN119677882A (de)
AU (1) AU2022472681A1 (de)
WO (1) WO2024028922A1 (de)

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5438207A (en) * 1977-08-31 1979-03-22 Nippon Steel Corp Purifying method for powder iron source containing nonferrous metals
JPS5466314A (en) * 1977-11-08 1979-05-28 Nippon Steel Corp Manufacture of reduced pellets
JPS5910411A (ja) 1982-07-09 1984-01-19 Toshiba Corp マンドレルミルの肉厚制御方法
JPS6237325A (ja) 1985-06-27 1987-02-18 Nippon Kokan Kk <Nkk> 焼成塊成鉱およびその製造方法
JPH0826416B2 (ja) 1987-04-21 1996-03-13 株式会社神戸製鋼所 耐クラスタリング性に優れた直接製鉄用または溶融還元製鉄用製鉄原料
JP2012062505A (ja) * 2010-09-14 2012-03-29 Kobe Steel Ltd 塊成物の製造方法
JP6724678B2 (ja) 2015-12-25 2020-07-15 日本製鉄株式会社 還元用原料及び還元用原料の製造方法
WO2017154840A1 (ja) * 2016-03-08 2017-09-14 株式会社神戸製鋼所 焼結ペレットの製造方法、還元鉄の製造方法、および焼結ペレット
CN109055729B (zh) * 2018-09-21 2020-07-31 中国科学院城市环境研究所 一种污泥生物炭资源化利用的方法
JP7374870B2 (ja) * 2020-09-03 2023-11-07 株式会社神戸製鋼所 鉄鉱石ペレット

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CN119677882A (zh) 2025-03-21
WO2024028922A1 (ja) 2024-02-08
US20260028688A1 (en) 2026-01-29
EP4549601A4 (de) 2025-12-17
AU2022472681A1 (en) 2025-02-13

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