EP4355471A1 - Procédé de traitement de fer spongieux - Google Patents

Procédé de traitement de fer spongieux

Info

Publication number
EP4355471A1
EP4355471A1 EP22732958.8A EP22732958A EP4355471A1 EP 4355471 A1 EP4355471 A1 EP 4355471A1 EP 22732958 A EP22732958 A EP 22732958A EP 4355471 A1 EP4355471 A1 EP 4355471A1
Authority
EP
European Patent Office
Prior art keywords
sponge iron
coating
core
coated
liquid
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.)
Granted
Application number
EP22732958.8A
Other languages
German (de)
English (en)
Other versions
EP4355471B1 (fr
EP4355471C0 (fr
Inventor
Cem SAHIN
Daniel Schubert
Falco LISCHKE
Thomas Baur
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.)
ThyssenKrupp Steel Europe AG
Original Assignee
ThyssenKrupp Steel Europe AG
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 ThyssenKrupp Steel Europe AG filed Critical ThyssenKrupp Steel Europe AG
Publication of EP4355471A1 publication Critical patent/EP4355471A1/fr
Application granted granted Critical
Publication of EP4355471B1 publication Critical patent/EP4355471B1/fr
Publication of EP4355471C0 publication Critical patent/EP4355471C0/fr
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • 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
    • C21B13/0086—Conditioning, transformation of reduced iron ores
    • C21B13/0093—Protecting against oxidation

Definitions

  • the invention relates to a method for treating sponge iron, in which, following the production of sponge iron, the sponge iron is coated with a coating to prevent reoxidation and/or corrosion.
  • lime-based coatings show good results in the so-called RUL test (refractoriness under load), they require a comparatively long time to harden after application. Furthermore, the lime-based coatings are particularly sensitive to impact and can quickly crumble under unfavorable dynamic loads.
  • the object of the present invention is to specify a method for treating sponge iron and a sponge iron coated with anti-reoxidation and/or corrosion, which or with which the aforementioned disadvantages can be substantially eliminated.
  • this object is achieved by a method having the features of claim 1.
  • the invention relates to a method for treating sponge iron, in which, following the production of sponge iron, the sponge iron is coated with a coating to prevent reoxidation and/or corrosion, the sponge iron as the core being brought into contact with a carbon-based liquid which forms the coating the core.
  • essentially a closed coating can form on the core, so that it can be ensured that the core is essentially completely surrounded by the liquid or that the coating completely covers the core. constantly enveloped. It can thereby be ensured that the core (sponge iron), which comprises metallic iron, has no contact with the environment and therefore does not reoxidize as quickly or as quickly.
  • the use of a carbon-based coating has no disadvantage when using the coated sponge iron either in a power-driven melter or in a blast furnace.
  • the carbon content can be increased both in the pig iron to be produced from the sponge iron and in the slag, for example to positively promote the downstream processing stages of the pig iron and the slag.
  • carbon or graphite is used as the carbon base, which is dispersed and/or dissolved in the liquid before application.
  • a carbon base in particle form is used with a particle size> 0 mm and up to 2 mm, in particular up to 1.5 mm, preferably up to 1 mm, so that they easily disperse, for example by stirring in the liquid and / or dissolve.
  • the liquid can be applied by soaking/dipping, spraying, brushing or pouring over the sponge iron. After application, dripping, for example by guiding and/or holding the sponge iron over a sieve, can allow excess liquid to be collected, collected, circulated and fed back to the application process. to economize on resources.
  • a roller burnishing drum or similar method can be used, in which the sponge iron is provided with the coating in a rotating drum or a rotating plate.
  • an aqueous solution is used as the liquid.
  • distilled water or deionized water is used.
  • "normal" water for example tap water
  • surfactants and/or suspension aids can also be admixed to the aqueous solution, in particular to lower the surface tension and/or to support the formation of a preferred suspension.
  • an aqueous-alcoholic solution is used as the liquid.
  • Alcohol is particularly suitable as a solvent, since it can also dissolve hydrophobic, i.e. water-insoluble, substances.
  • isopropanol or ethanol can be used as a solvent.
  • Other aqueous-alcoholic solutions not mentioned here can also be used.
  • an aqueous, organic, in particular non-alcoholic solution can also be considered as a liquid, for example polyacrylic acid.
  • the sponge iron coated with the liquid can be dried, in particular actively with the supply of heat.
  • the sponge iron coated with the liquid has a temperature above the ambient temperature up to, for example, a maximum of 150°C, in particular a maximum of 120°C, preferably a maximum of 90°C
  • the sponge iron has a temperature before application which above the ambient temperature up to, for example, a maximum of 150° C., in particular a maximum of 120° C., preferably a maximum of 90° C., in order to expel the volatile constituents as quickly as possible and to achieve rapid hardening of the coating.
  • the invention further relates to a sponge iron coated to prevent reoxidation and/or corrosion, having a core and a coating, the sponge iron comprising metallic iron as the core, the coating comprising carbon.
  • the sponge iron has metallic iron as its main component, i.e. more than 70%, in particular more than 80%, preferably more than 90% in the entire structure and thus depends on the composition of the iron ore originally used. Sponge iron with less than 70% metallic iron in the structure cannot be used economically.
  • other components can be silicon dioxide (Si0 2 ) or also called quartz, depending on the degree of reduction and wustite (FeO), hematite (Fe 2 03), magnetite (Fe 3 0 4 ) and/or depending on the composition Composition of the reducing gas during the direct reduction can also be cementite (Fe 3 C), so that the components in the structure of the sponge iron or core contain up to 30%, in particular up to 20%, preferably up to 10%, along with unavoidable impurities could be.
  • Impurities can be understood, for example, as traces of titanite (CaSiTi0 5 ), albite (NaAISi 3 0 8 ) and/or mixed crystals between diopside (CaMgSi 2 0 6 ) and hedenbergite (CaFe 2+ Si 2 0 6 ).
  • the coating comprises carbon as the main component with at least 90%, in particular at least 95%, preferably at least 98% in the composition of the coating.
  • Other components can be silicon dioxide (Si0 2 ), glass phase (Si-Fe-Ca-Mg-Al-Na), potassium feldspar (KAISi 3 0 8 ), wustite (FeO), hematite (Fe 2 0 3 ) and/or magnetite (Fe 3 0 4 ), one or more of the components mentioned, so that the components of the coating can be up to 10%, in particular up to 5%, preferably up to 2%, together with unavoidable impurities.
  • Impurities can be understood as meaning, for example, the aforementioned components, individually or several of the aforementioned if they are present in traces, for example less than 0.1%.
  • Lime (Ca-C0 3 ), magnesium oxide (MgO) and/or alkalis can also be present as impurities.
  • the components of the mixture of substances mentioned in the present text can be determined using a light microscope, scanning electron microscope and Electron Back Scattered Diffraction "EBSD".
  • EBSD Electron Back Scattered Diffraction
  • the coating can also include silicon dioxide as a component in addition to carbon, for example >0% to a maximum of 10%, in particular up to a maximum of 5%, preferably up to a maximum of 2%.
  • a transition region can be formed between the core and the coating, which contains at least one of the components silicon dioxide (Si0 2 ), glass phase (Si-Fe-Ca-Mg-Al-Na), wustite (FeO), hematite (Fe 2 0 3 ) and magnetite (Fe 3 0 4 ).
  • the transition area can essentially be reduced to the area which has a proportion of metallic iron of less than 40%, in particular less than 30%, preferably less 20% and a carbon content of less than 40%, in particular less than 30%, preferably less than 20%.
  • the rest of the structure in the transition area thus has one or more of the components mentioned, along with impurities.
  • the thickness or radial thickness can vary and is therefore not present uniformly with a constant thickness when viewed over the circumference.
  • FIG. 1 shows an evaluation of an RUL test on four different sponge iron samples.
  • Sponge iron was provided in pellet form with a fraction of 10 to 12.5 mm originating from a direct reduction plant.
  • the first pellet samples (1) were used as uncoated reference samples;
  • the second pellet samples (2) were coated with a lime-based coating, using a mixture of milk of lime Ca(OH) 2 comprising quicklime/white fine lime/CaO mixed with water at a ratio of 150 - 350 grams of CaO per liter of H 2 0 , was created;
  • the third pellet samples (3) were coated with an aqueous-alcoholic solution carbon coating, available as a product from James Durran under the designation RSB 5302-01, which is based on a mixture of carbon size (graphite) with isopropanol, and
  • the fourth pellet samples (4) were coated with an aqueous solution carbon coating, available as a product from James Durran under the designation RWB 5802-01, which is based on a mixture of carbon (graphit
  • pellet samples (2)-(4) were each immersed in a liquid described above and then conveyed onto a sieve, on which excess liquid was allowed to drip off.
  • Pellet samples (2)-(4) were not actively heat applied, so curing of the liquid on the sponge iron pellets could occur naturally under ambient conditions to a coating.
  • Pellet samples (3) and (4) were dry within minutes. In the case of the pellet samples (2), this process took a very long time (> 24 h). An active supply of heat could possibly have led to accelerated drying/curing.
  • contact surfaces formed due to agglomeration of individual coated pellets connected to one another, and the coating of milk of lime crumbled slightly. This phenomenon also occurred occasionally during the drying of the pellet samples (3). Furthermore, the coating occasionally showed no regularity. There were no abnormalities when processing the pellet samples (4). All pellet samples (2) - (4) showed a high "absorbing" property, so that the use of the respective coating solution was very high in comparison. At least the water-based solutions could be post-diluted.
  • the four different pellet samples (1) - (4) were subjected to a so-called RUL test.
  • a gas-flow furnace in which the atmosphere and the temperature can be varied over time, was used as the device for this test.
  • Phases 1 to 4 listed in Table 1 and the corresponding parameters were run through so that the evaluation shown in FIG. 1 was achieved as a result.
  • the pellet samples (1) - (3) behaved almost the same, only the pellet samples (4) experienced a high weight loss up to approx. 350 °C. It was actually to be expected that the pellet samples (2) should also show a comparable result to the pellet samples (4) due to the water-based solution. The reason that surprisingly no weight loss was observed in the pellet samples (2 ) occurred in the stated temperature range is explained by the formation of calcium hydroxide.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)
  • Chemical Treatment Of Metals (AREA)
  • Manufacture Of Iron (AREA)
  • Paints Or Removers (AREA)

Abstract

L'invention concerne un procédé de traitement d'un fer spongieux. Selon l'invention, après la production du fer spongieux, le fer spongieux est revêtu d'un revêtement permettant de le protéger contre la réoxydation et/ou la corrosion, le fer spongieux sous forme de noyau étant mis en contact avec un liquide à base de carbone destiné à former un revêtement sur le noyau.
EP22732958.8A 2021-06-18 2022-06-02 Procédé de traitement de l'éponge de fer et éponge de fer Active EP4355471B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102021115807.9A DE102021115807A1 (de) 2021-06-18 2021-06-18 Verfahren zum Behandeln von Eisenschwamm
PCT/EP2022/065052 WO2022263189A1 (fr) 2021-06-18 2022-06-02 Procédé de traitement de fer spongieux

Publications (3)

Publication Number Publication Date
EP4355471A1 true EP4355471A1 (fr) 2024-04-24
EP4355471B1 EP4355471B1 (fr) 2025-11-05
EP4355471C0 EP4355471C0 (fr) 2025-11-05

Family

ID=82163364

Family Applications (1)

Application Number Title Priority Date Filing Date
EP22732958.8A Active EP4355471B1 (fr) 2021-06-18 2022-06-02 Procédé de traitement de l'éponge de fer et éponge de fer

Country Status (5)

Country Link
EP (1) EP4355471B1 (fr)
CN (1) CN117500581A (fr)
DE (1) DE102021115807A1 (fr)
ES (1) ES3057416T3 (fr)
WO (1) WO2022263189A1 (fr)

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3556838A (en) * 1966-11-01 1971-01-19 Exxon Research Engineering Co Process for coating active iron and the coated iron
US3628986A (en) * 1969-08-22 1971-12-21 Exxon Research Engineering Co Water-repellent reduced iron ore
US3833343A (en) * 1971-04-28 1974-09-03 Carbo Scrap Process for production of carbon-bearing scrap and product
DE2326174C2 (de) * 1973-05-23 1979-03-29 Kloeckner-Werke Ag, 4100 Duisburg Einschränkung der Oxydation des Einsatzes beim Einschmelzen von Schrott o.dgl
AT350600B (de) 1977-08-25 1979-06-11 Voest Ag Verfahren zur behandlung von eisenschwamm zum verhindern der reoxidation und vorrichtung zur durchfuehrung dieses verfahrens
SE8003999L (sv) 1980-05-29 1981-11-30 Bergstedth Henri Klettersko for anvendning vid stolpar
AT367097B (de) 1980-06-11 1982-05-25 Voest Alpine Ag Verfahren zum behandeln von metallischen huetteneinsatzstoffen, insbesondere eisenschwammteilchen
EP0042236A1 (fr) 1980-06-13 1981-12-23 Alan Worswick Machine et méthode d'empilage
US4329168A (en) * 1980-07-01 1982-05-11 Rubio Charles A Amine treatment for passivating sponge iron
JP2002363625A (ja) * 2001-06-05 2002-12-18 Kobe Steel Ltd 表面被覆還元鉄、その製造方法および溶解方法

Also Published As

Publication number Publication date
ES3057416T3 (en) 2026-03-02
EP4355471B1 (fr) 2025-11-05
WO2022263189A1 (fr) 2022-12-22
EP4355471C0 (fr) 2025-11-05
CN117500581A (zh) 2024-02-02
DE102021115807A1 (de) 2022-12-22

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