WO2000011227A1 - Produit long utilise pour la desulfuration d'un bain d'acierage - Google Patents

Produit long utilise pour la desulfuration d'un bain d'acierage Download PDF

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Publication number
WO2000011227A1
WO2000011227A1 PCT/SE1999/001442 SE9901442W WO0011227A1 WO 2000011227 A1 WO2000011227 A1 WO 2000011227A1 SE 9901442 W SE9901442 W SE 9901442W WO 0011227 A1 WO0011227 A1 WO 0011227A1
Authority
WO
WIPO (PCT)
Prior art keywords
reactive composition
cao
product according
composition contains
envelope
Prior art date
Application number
PCT/SE1999/001442
Other languages
English (en)
Swedish (sv)
Inventor
Daniel SVÄRD
Original Assignee
Partek Nordkalk Aktiebolag
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 Partek Nordkalk Aktiebolag filed Critical Partek Nordkalk Aktiebolag
Priority to AU57684/99A priority Critical patent/AU5768499A/en
Priority to EP99944972A priority patent/EP1112388A1/fr
Publication of WO2000011227A1 publication Critical patent/WO2000011227A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/02—Dephosphorising or desulfurising
    • C21C1/025—Agents used for dephosphorising or desulfurising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/064—Dephosphorising; Desulfurising

Definitions

  • the invention concerns an elongated product comprising at least one portion, in the following termed reactive composition, that is reactively active when being submerged in a bath of molten steel for the treatment of such melts, particularly for desulphurization and for modification of inclusions.
  • Sulphur has an unlimited solubility in steel at high temperatures, but the solubility is greatly reduced when the steel solidifies. This leads to precipitation of iron sulphides which have a melting point far below that of the steel. The molten iron sulphide will be deposited in grain boundaries, which can cause cracking during working.
  • Aluminium is a very strong deoxidation agent, but the Al 2 O 3 that is formed through the reaction between added aluminium and oxygen that is dissolved in the melt has a high melting point and forms solid clusters which cause problems in connection with continuous casting.
  • the purpose of the invention to provide a new reactive mixture in the form of an elongated product, preferably in the form of a wire and in the following referred to as wire, which allows a combined action of desulphurization and modification of inclusions, which is not possible by means of known products of today, particularly for treating steel melts which need to be desulphurized, e.g. melts which contain at least 150 ppm sulphur.
  • the reactive portion of the wire consists of a material composition which contains in weight-% 35-75 % (CaO + CaCO 3 ) and 30-70 % CaSi.
  • the reactive composition contains at least 15 % CaO when the reactive composition also contains CaCO 3 which is decomposed to CaO + CO 2 in the melt.
  • CaO reacts with dissolved sulphur, oxygen being dissolved in the melt, whether CaO is added in the form of lime (CaO) or is obtained through the decomposition of CaC0 3 .
  • This oxygen is taken up by Ca (from CaSi) and by Si and by possibly existing Al.
  • the reactive composition of the product contains at least 2 weight-% Al. A conceivable content is 2-10 % Al or 2-5 % Al.
  • the optimal content of the agents included in the reactive composition depends on the composition of the melt that shall be treated, in the first place the content of oxygen and sulphur.
  • aluminium in the reactive composition of the product can be excluded.
  • the composition contains 15-45 % CaO. More precisely the content of CaO may amount to 35-45 %, 15-25 % or 30-40 % within the scope of this application. According to another application the content of CaO amounts to 40-60 %.
  • the reactive composition contains 5-30 % CaC0 3 or, more precisely depending on the application, 20-30 % CaC0 3 or 5-15 % CaCO 3 .
  • the content of CaO may, for example, amount to 15-25 %. In the case the reactive composition does not contain CaCO 3 , the content of CaO may, for example, amount to 35-45 %.
  • the composition contains 15-45 % CaO, 40-60 % CaSi and 2-5 Al.
  • the reactive composition contains 30-40 % CaO, 40-60 % CaSi, 3-8 % Al and 5-15 % CaCO 3 .
  • the purpose of the aluminium in the wire that shall be injected in the steel melt is to provide a very low oxygen activity in the injection region and thence locally improve the preconditions for the desulphurization at the same time as conditions are created of a good control of the Al-yield and thence also of the Al-content in the melt, which can allow a comparatively low consumption of aluminium and improved desulphurization, because compensation for reoxidation is facilitated.
  • a wire which contains aluminium in the reactive composition is particularly advantageous for the treatment of steel melts having a high oxygen activity, e.g. 20 ppm or more, and above all for treating steels which have a high oxygen activity in combination with a high sulphur content.
  • a certain amount of CaO is replaced by CaCO 3 , wherein an improved desulphurization can be obtained through calcination and decomposition of CaCO 3 to form CaO and C0 2 (g), which leads to the generation of very fine CaO grains having a large reaction surface, in combination with an increased stirring of the bath as C0 2 (g) rises towards the surface.
  • an improved desulphurization can be obtained through calcination and decomposition of CaCO 3 to form CaO and C0 2 (g), which leads to the generation of very fine CaO grains having a large reaction surface, in combination with an increased stirring of the bath as C0 2 (g) rises towards the surface.
  • CaSi shall exist in an amount of at least 30 %, preferably at least 40 % in order to provide desired deoxidation through its content of Si, at the same time as the hard aluminium oxide clusters that are formed in connection with the oxidation of aluminium which also shall take place in the melt, are modified to calcium aluminates of the type (CaO) i 2 (Al 2 O 3 ) 7 inclusions due to the CaSi calcium.
  • the reactive composition should contain at least 15 % CaO.
  • the upper limit of CaSi which is 70 %, preferably max.
  • the mixture of reactive agents i.e. the reactive composition
  • the mixture of reactive agents contains max. 8 % Al, but also max. 5 % Al can be sufficient for many applications.
  • the effect that is achieved by the replacement of a certain amount of CaO by CaC0 3 has been mentioned above.
  • the content of CaCO in the mixture of reactive agents should amount to at least 5 %, and according to an embodiment to at least 20 %.
  • the injection of CaCO 3 causes a local reduction of the temperature in the melt. Further the injection of CaC0 3 leads to a certain increase of the carbon content. Therefore the content of CaC0 3 should be limited to max. 30 %. According to a conceivable embodiment the composition contains 5-15 %.
  • the elongated product - the wire - may physically - i.e. from a design point of view - be shaped in many different ways within the scope of the invention. It shall have a sufficient bendability in order to be able to be coiled and uncoiled on and from a drum but at the same time have sufficient stiffness in order to be able to be fed down through a slag cover on the surface of a metal melt in a treatment ladle and be submerged in the melt down to as close to the bottom as possible, e.g. to a depth of at least about 2 m, which are requirements that the wire shall satisfy.
  • the wire has a substantially circular cross section with a diameter of 10-25 mm.
  • Wires having outer diameters of 13 mm and 16 mm have been found to function very well. Further the wire shall be designed in such a way - and this particularly concerns the tube- or hose-shaped enclosure of the wire - that the mixture of reactive agents, i.e. the reactive composition, does not react with the melt until at a desired depth beneath the surface of the melt, i.e. as near the bottom as possible.
  • the mixture of reactive agents i.e. the reactive composition
  • the envelope of the wire consists of a tube or a hose of metal, suitably a metal which will be molten and be included in the metal melt, preferably without reacting chemically with elements in the melt.
  • the envelope consists of a tube or a hose of steel having a sufficient thickness in order to give the wire sufficient strength, however, not thicker than the wire can be coiled and uncoiled on and from a drum.
  • Fig. 1-Fig. 7 shows the wire of the invention in cross section according to some conceivable embodiments.
  • Fig. 1 shows a wire consisting of a seamless steel tube la, which contains a powder or grain shaped product 2 consisting of said reactive composition.
  • Fig. 2 shows a wire consisting of a butt-welded steel tube lb containing said reactive composition 2.
  • Fig. 3 shows a lap-seam welded or glued steel pipe lc containing said reactive composition 2.
  • Fig. 4 shows a lockseamed steel pipe Id containing said reactive composition 2.
  • Fig. 5 shows a butt welded pipe la, which contains an aluminium wire 3, which is responsible for the intended aluminium content in the composition and is embedded in a reactive powder or grain shaped product 2', which contains the other ingredients in the reactive composition.
  • Fig. 6 shows a butt-welded pipe la, which on the inside is covered by a sheet of aluminium or which contains a strip 3' of aluminium.
  • the reactive mixture 2' in the same mode as according to Fig.
  • Fig. 7 shows a lockseamed steel pipe Id' which is provided with a longitudinal indentation 4 for close-packing the reactive mixture 2, the indentation being performed after the tube Id' has been filled and sealed through the lockseam.
  • the thickness of the steel pipe has been strongly exaggerated.
  • the mixture of reactive agents contains in weight-% 38-42 % CaO, 3-4 % Al and 55-60 % CaSi.
  • An example of a composition according to this first embodiment is a composition consisting of 39.3 % CaO, 3.6 % Al and 57.1 % CaSi.
  • the reactive composition in the wire according to the invention contains in weight-%: 18-24 % CaO, 2.5-4 % Al, 45-55 % CaSi and 22-28 % CaCO 3 .
  • An example of such preferred embodiment is a composition which consists of 21.3 % CaO, 3.2 % Al, 50.2 % CaSi and 25.4 % CaCO 3 .
  • the reactive composition in the wire of the invention contains in weight-% 33-38 % CaO, 3-8 % Al, 45-55 % CaSi och 7-13 % CaCO 3 .
  • An example of such preferred embodiment is a composition which consists of 35 % CaO, 5 % Al, 50 % CaSi and 10 % CaCO 3 .
  • CaO, CaSi and CaC0 3 exist as powder or grains or as an agglomerate in the tubular envelope, while the aluminium either may exist as a powder or as larger particles in the mixture and/or as a wire, sheet, strip, or the like inside the envelope. In principle it is also conceivable that the aluminium exists as part of or on the inside of the envelope.
  • the wire, besides iron in the envelope, which are not included in the said percentages, may contain other components, provided that such components do not impair the intended desulphurization and modification of inclusions.
  • further components may include, but are not restricted to, e.g. boron and misch metal.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Abstract

Ce produit long comporte au moins une partie, en l'occurrence la composition réactive, qui, dès qu'elle est plongée dans un bain d'acier en fusion, entre en réaction de traitement de tels bains, en vue d'une désulfuration et d'une modification des inclusions. Cette composition réactive contient pour 35 % à 75 % de sa masse un mélange de CaO + CaCO3, et pour 30 % à 70 % de sa masse du CaSi.
PCT/SE1999/001442 1998-08-25 1999-08-25 Produit long utilise pour la desulfuration d'un bain d'acierage WO2000011227A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU57684/99A AU5768499A (en) 1998-08-25 1999-08-25 Elongated product used for desulphurization of a steel bath
EP99944972A EP1112388A1 (fr) 1998-08-25 1999-08-25 Produit long utilise pour la desulfuration d'un bain d'acierage

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9802823A SE512574C2 (sv) 1998-08-25 1998-08-25 Långsträckt produkt som är verksam vid nedsänkning i ett bad av smält stål för svavelrening
SE9802823-6 1998-08-25

Publications (1)

Publication Number Publication Date
WO2000011227A1 true WO2000011227A1 (fr) 2000-03-02

Family

ID=20412334

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1999/001442 WO2000011227A1 (fr) 1998-08-25 1999-08-25 Produit long utilise pour la desulfuration d'un bain d'acierage

Country Status (4)

Country Link
EP (1) EP1112388A1 (fr)
AU (1) AU5768499A (fr)
SE (1) SE512574C2 (fr)
WO (1) WO2000011227A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005090614A1 (fr) * 2004-03-23 2005-09-29 Tamas Istvan Nouveaux agents de desulfuration permettant de diminuer la teneur en soufre de coulees de fonte a un niveau ultra bas
CN100381586C (zh) * 2006-01-17 2008-04-16 沈阳东北大学冶金技术研究所 一种钢水脱氧用包芯线
JP2017031437A (ja) * 2015-07-28 2017-02-09 日新製鋼株式会社 溶銑の脱硫方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1986004359A1 (fr) * 1985-01-24 1986-07-31 Vallourec Procede de traitement de metaux liquides par fil fourre contenant du calcium
EP0281485A1 (fr) * 1987-02-03 1988-09-07 Affival Produit composite à enveloppe tubulaire pour le traitement des bains métalliques fondus
EP0355526A2 (fr) * 1988-08-23 1990-02-28 Giovanni Crespi Agent de désulfuration pour laitiers basiques d'acier et procédé pour sa fabrication

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1986004359A1 (fr) * 1985-01-24 1986-07-31 Vallourec Procede de traitement de metaux liquides par fil fourre contenant du calcium
EP0281485A1 (fr) * 1987-02-03 1988-09-07 Affival Produit composite à enveloppe tubulaire pour le traitement des bains métalliques fondus
EP0355526A2 (fr) * 1988-08-23 1990-02-28 Giovanni Crespi Agent de désulfuration pour laitiers basiques d'acier et procédé pour sa fabrication

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005090614A1 (fr) * 2004-03-23 2005-09-29 Tamas Istvan Nouveaux agents de desulfuration permettant de diminuer la teneur en soufre de coulees de fonte a un niveau ultra bas
CN100381586C (zh) * 2006-01-17 2008-04-16 沈阳东北大学冶金技术研究所 一种钢水脱氧用包芯线
JP2017031437A (ja) * 2015-07-28 2017-02-09 日新製鋼株式会社 溶銑の脱硫方法

Also Published As

Publication number Publication date
SE512574C2 (sv) 2000-04-03
EP1112388A1 (fr) 2001-07-04
AU5768499A (en) 2000-03-14
SE9802823L (sv) 2000-02-26
SE9802823D0 (sv) 1998-08-25

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