EP0431772B1 - Entschwefelungsmittel für geschmolzenes Metall - Google Patents

Entschwefelungsmittel für geschmolzenes Metall Download PDF

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Publication number
EP0431772B1
EP0431772B1 EP90312432A EP90312432A EP0431772B1 EP 0431772 B1 EP0431772 B1 EP 0431772B1 EP 90312432 A EP90312432 A EP 90312432A EP 90312432 A EP90312432 A EP 90312432A EP 0431772 B1 EP0431772 B1 EP 0431772B1
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EP
European Patent Office
Prior art keywords
agent according
agent
desulphurising
magnesium
weight
Prior art date
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Application number
EP90312432A
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English (en)
French (fr)
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EP0431772A1 (de
Inventor
Edmund Fuchs
Helmuth Jaunich
Wolfram Florin
Erich Hoffken
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.)
Foseco International Ltd
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Foseco International Ltd
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Publication of EP0431772A1 publication Critical patent/EP0431772A1/de
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Classifications

    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/10General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals with refining or fluxing agents; Use of materials therefor, e.g. slagging or scorifying agents
    • C22B9/103Methods of introduction of solid or liquid refining or fluxing agents
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21CPROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00Refining of pig-iron; Cast iron
    • C21C1/02Dephosphorising or desulfurising
    • C21C1/025Agents used for dephosphorising or desulfurising

Definitions

  • the present invention relates to an agent for desulphurising molten metals, for example, of liquid pig iron, consisting of granular magnesium particles, each of which comprises a plurality of coatings.
  • Desulphurising agents which consist of a mixture of finely divided magnesium particles and further substances of desulphurising effect, like lime, calcium carbide, limestone and dolomite, are known, e.g. from German Patent No. 3000927 and from U.S. Patent No. 4182626. It is a disadvantage of these desulphurising agents that there occur problems in storage and transport, e.g. by a separation of the agent into its components. There is furthermore the danger that the magnesium of the agent reacts with humidity, resulting in the formation of hydrogen. Problems may also result from the introduction of the desulphurising agent into the liquid molten metal due to the violent reaction of the magnesium with the molten metal.
  • a further disadvantage of this desulphurising agent is that the impregnated magnesium is unprotected at the outside, that there is the danger of abrasion so that pure magnesium dust can occur besides granular Mg-mixtures.
  • the magnesium furthermore is located at the outside of the grain so that under the action of humidity the development of hydrogen may occur.
  • the indicated components MgO, lime and alumina are to act as diluent for the magnesium in the desulphurising agents, in order to inhibit or minimise the undesired evaporation of the magnesium. They are, furthermore, intended to weaken the violent reaction of the magnesium.
  • the disadvantages of this desulphuriser further consist in that pure magnesium only exists after the reduction with, e.g. C or Al, and thus can only react thereinafter. Within the short period of injection and rising in the metal bath this desired reaction can only take place insufficiently.
  • a desulphurising agent in which finely divided magnesium particles exhibit a first coating of a hydrophobic compound, in particular oil, and a second coating of finely divided refractory material.
  • the refractory material of the second coating can consist of one or several substances, selected from the group of alumina, magnesia, silica, titanium oxide, lime, dolomite, calcium carbonate, calcium aluminates, other refractory aluminates, refractory silicates or aluminosilicates.
  • the second coating of refractory material can consist of a first and a second coating itself, the nature of the coatings being identical or different. It is a disadvantage of this desulphurising agent that the coatings substantially are no desuphurising agents, but only ballast substances.
  • hydrophobic compound e.g. epoxide resin or novolak resin for the first coating and soda ash for the second coating.
  • epoxide resin or novolak resin for the first coating
  • soda ash for the second coating.
  • the use of the mentioned organic substance proved to be unfavorable, since during the application a solvent or a curing agent is necessary which can be injurious to the health of the personnel when using the desulphurising agent. Furthermore, the efficiency of the desulphurising agent is not improved either.
  • an agent for desulphurising molten metal comprises fine granular magnesium particles, each particle having a plurality of coatings, in which the first coating immediately enveloping the magnesium particle is of silicic acid (silica) of very finely-divided structure (and therefore, large specific surface) in colloidal and/or amorphous and/or crystalline and/or fumed form. Because of their finely-divided structure and their large surface, these substances act as lubricating agents and simultaneously as slag liquifying agent for the further coatings.
  • a coating of the indicated substance can, furthermore, be applied on the magnesium particles in a thinner thickness of the layer than the known oil-coating, so that, because of this, the proportion of the further coatings can be increased.
  • the magnesium particles may have further coatings of less reactive desulphurising agents to serve as protective coatings, particularly with regard to the absorbance of humidity and to avoid the formation of hydrogen.
  • the highly reactive desulphurising agents are preferably selected from the group of alkaline earths and alkalis, e.g. calcium oxide and sodium carbonate, while the less reactive desulphurising agents are selected from the group of the alkalis and alkaline earths, like e.g. calcium borate, calcium carbonate, Ca(OH)2, calcium aluminate and sodium borate.
  • alkaline earths and alkalis e.g. calcium oxide and sodium carbonate
  • the less reactive desulphurising agents are selected from the group of the alkalis and alkaline earths, like e.g. calcium borate, calcium carbonate, Ca(OH)2, calcium aluminate and sodium borate.
  • the magnesium particle may have further coatings containing one or more fluxes and/or one or more agents for the removal of nitrogen.
  • the flux is preferably selected from the group of colemanite, fluorspar, cryolite and SiO2, while the deoxidant is preferably selected from the group of aluminium, calcium-silicon and carbons and magnesium.
  • the agent for removing nitrogen is preferably selected from the group of titanium, aluminium, vanadium, nickel, sodium and magnesium.
  • the size of the granular magnesium is preferably in the range 0.15 to 1.00 mm and the proportion of the magnesium in the coated particle of the desulphurising agent should be from 1% to 90% by weight and is preferably in the range from 15% to 80% by weight.
  • the proportion of the ingredients of the first coating in the coated particle is preferably from 0.5 to 5% by weight.
  • the finely divided silica in the colloidal and/or amorphous and/or crystalline and/or the fumed form preferably has a particle size within the range 0.1 to 5 »m.
  • the desulphurising agent preferably has a grain size of less than 60 »m and is present in the coated particle in an amount from 5 to 25% by weight. However, where a less reactive desulphurising agent is employed the grain size may be less than 90 »m and the agent preferably is present in an amount up to 35% by weight.
  • the proportion of flux in the coated particle is preferably from 1 to 25% by weight and the grain size of the flux is less than 40 »m.
  • the proportion of deoxidant in the coated particle is also preferably from 1 to 25% by weight and the grain size of the deoxidant is also less than 40 »m.
  • the proportion of that agent in the coated particle is preferably also from 1 to 25% by weight and the grain size of the agent is also less than 40 »m.
  • the preferred desulphurising agent used is a free-flowing soft quicklime.
  • the grain size of this soft quicklime is within the range of ⁇ 30 »m, preferably within the range of ⁇ 16 »m.
  • the possibility of different kinds of substance combinations provides the advantage that the slag from the reaction products can be conditioned such that improved deposit properties result. Apart from this the slags conditioned such can be re-used in the process for pig iron production.
  • a desulphurising agent on the basis of magnesium particles provided with coatings was produced on a plant scale and consisted of the following components in % by weight:
  • the magnesium had an average particle size of 0.5 mm, the colloidal silica had an average particle size of 0.2 »m.
  • the free-flowing soft quicklime and the aluminium each had an average grain size of 90% ⁇ 100 »m.
  • the magnesium and the colloidal silica were mixed in a high energy mixer (Eirich mixer) for a period of 5 minutes. Subsequently, there was at first added the free-flowing soft quicklime and the mixing was continued for a period of 5 minutes. Finally, the aluminium was added and stirring was continued for another period of 5 minutes.
  • the degree of protection against the absorption of water allowed to those magnesium particles having a coating of colloidal silica and the further coatings of free-flowing soft quicklime and aluminium, was estimated by immersing the coated particles into water and by measuring the formation of hydrogen.
  • the degree of abrasion during the conveyance of the magnesium particles having a coating of colloidal silica and the further coatings of free-flowing soft quicklime and aluminium, in a conveying conduit of 120 m of length was determined to be 14% by weight.
  • a comparable desulphurising agent which did not have a coating of colloidal silica exhibited an abrasion of 23% by weight.
  • a desulphurising agent on the basis of magnesium particles provided with coatings was produced on a plant scale and consisted of the following components in % by weight:
  • the magnesium had an average particle size of 0.5 mm, the colloidal silica had an average particle size of 0.2 »m.
  • the free flowing soft quicklime and the fluor spar each had an average grain size of 90% ⁇ 40 »m.
  • the magnesium and the silica were mixed in a high energy mixer (Eirich mixer) for a period of 5 minutes. Subsequently, there was at first added the free-flowing soft quicklime and the mixing was continued for a period of 5 minutes. Finally, the fluor spar was added and stirring was continued for another period of 5 minutes.
  • the coated magnesium particles were separated from the non-adhering particles of colloidal silica, soft quicklime and fluor spar.
  • the proportion of the non-adhering particles was determined to be 11% by weight.
  • the degree of protection against the absorption of water which is allowed to those magnesium particles having a coating of colloidal silica and the further coatings of free-flowing soft quicklime and fluor spar, are estimated by immersing the coated particles into water and by measuring the formation of hydrogen.
  • the formation of hydrogen was determining to be 0.5 1/kg ⁇ h.
  • pig iron charges having an initial temperature of 1320°C were desulphurised.
  • the results are shown in Table 2a.
  • Table 2b there are furthermore, shown the respective amounts of slag in kg/t RE (pig iron) and the pig iron losses in kg/t RE (pig iron).
  • a desulphurising agent on the basis of magnesium particles provided with coatings was produced on a plant scale and consisted of the following components in % by weight:
  • the magnesium had an average particle size of 0.5 mm, the colloidal silica had a average particle size of 0.2 »m.
  • the lime and the soda each had an average grain size of 90% ⁇ 100 »m.
  • the magnesium and the colloidal silica were mixed in a high energy mixer (Eirich mixer) for a period of 5 minutes. Subsequently, there was at first added the lime and the mixing was continued for a period of 5 minutes. Finally, soda was added and mixing was continued for another period of 5 minutes.
  • the degree of protection against the absorption of water allowed to those magnesium particles having a coating of colloidal silica and the further coatings of lime and soda, was estimated by immersing the coated particles into water and by measuring the formation of hydrogen.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Claims (26)

  1. Mittel zur Entschwefelung schmelzflüssiger Metalle, bestehend aus granulären Magnesiumteilchen, wobei jedes dieser Magnesiumteilchen eine Mehrzahl Beschichtungen aufweist, dadurch gekennzeichnet, daß die erste, das Magnesiumteilchen direkt umhüllende Beschichtung aus Kieselsäure sehr fein verteilter Struktur in kolloidaler und/oder amorpher und/oder kristalliner und/oder rauchartiger Form besteht und die Struktur der weiteren Beschichtungen aus einem oder mehreren, hoch reaktionsfähigen Entschwefelungsmitteln besteht.
  2. Mittel nach Anspruch 1, dadurch gekennzeichnet, daß die Magnesiumteilchen ferner eine oder mehrere Beschichtungen aus weniger reaktionsfähigen Entschwefelungsmitteln enthalten.
  3. Mittel nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Magnesiumteilchen ferner weitere Beschichtungen aus einem oder mehreren Flußmitteln und/oder einem oder mehreren Desoxidatoren enthalten.
  4. Mittel nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die Magnesiumteilchen ferner Beschichtungen aus einem oder mehreren Mitteln zur Entfernung von Stickstoff enthalten.
  5. Mittel nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß die hoch reaktionsfähigen Entschwefelungsmittel aus der Gruppe Calciumoxid und Natriumcarbonat ausgewählt sind.
  6. Mittel nach einem der Ansprüche 2 bis 5, dadurch gekennzeichnet, daß die weniger reaktionsfähigen Entschwefelungsmittel aus der Gruppe der Alkalien und Erdalkalien wie z.B. Calciumcarbonat, Calciumborat, Calciumaluminat und Natriumborat ausgewählt sind.
  7. Mittel nach einem der Ansprüche 3 bis 6, dadurch gekennzeichnet, daß das Flußmittel aus der Gruppe Colemanit, Flußspat, Kryolith und Kieselsäure ausgewählt ist.
  8. Mittel nach einem der Ansprüche 3 bis 7, dadurch gekennzeichnet, daß der Desoxidator aus der Gruppe Aluminium, Calcium-Silizium, Kohlenstoff und Magnesium ausgewählt ist.
  9. Mittel nach einem der Ansprüche 4 bis 8, dadurch gekennzeichnet, daß das Mittel zur Entfernung von Stickstoff aus der Gruppe Titan, Aluminium, Vanadium, Nickel, Natriumcarbonat und Magnesium ausgewählt ist.
  10. Mittel nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Anteil des Magnesiums in dem beschichteten Teilchen 1 bis 90 Gew.-% beträgt.
  11. Mittel nach Anspruch 10, dadurch gekennzeichnet, daß der Anteil an Magnesium 15 bis 80 Gew.-% beträgt.
  12. Mittel nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Anteil der Kieselsäure feinverteilter Struktur im beschichteten Teilchen zwischen 0,5 und 5 Gew.-% liegt.
  13. Mittel nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Anteil des Entschwefelungsmittels im beschichteten Teilchen 5 bis 25 Gew.-% beträgt.
  14. Mittel nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Anteil des weniger reaktionsfähigen Entschwefelungsmittels in den beschichteten Teilchen bis zu 35 Gew.-% beträgt.
  15. Mittel nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Anteil Flußmittel im beschichteten Teilchen 1 bis 25 Gew.-% beträgt.
  16. Mittel nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Anteil Desoxidator im beschichteten Teilchen 1 bis 25 Gew.-% beträgt.
  17. Mittel nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Anteil des Mittels zur Entfernung von Stickstoff im beschichteten Teilchen 1 bis 25 Gew.-% beträgt.
  18. Mittel nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die Korngröße der Kieselsäure sehr fein verteilter Struktur im Bereich von 0,1 bis 5 »m liegt.
  19. Mittel nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die Korngröße des Entschwefelungsmittels im Bereich < 60 »m liegt.
  20. Mittel nach einem der Ansprüche 2 bis 19, dadurch gekennzeichnet, daß die Korngröße des weniger reaktionsfähigen Entschwefelungsmittels im Bereich < 90 »m liegt.
  21. Mittel nach einem der Ansprüche 3 bis 20, dadurch gekennzeichnet, daß die Korngröße des Flußmittels im Bereich < 40 »m liegt.
  22. Mittel nach einem der Ansprüche 3 bis 21, dadurch gekennzeichnet, daß die Korngröße des Desoxidators im Bereich < 40 »m liegt.
  23. Mittel nach einem der Ansprüche 4 bis 22, dadurch gekennzeichnet, daß die Korngröße des Mittels zur Entfernung von Stickstoff im Bereich < 40 »m liegt.
  24. Mittel nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß ein freifließender weicher Ätzkalk als Entschwefelungsmittel verwendet wird.
  25. Mittel nach Anspruch 24, dadurch gekennzeichnet, daß die Korngröße des weichen Ätzkalks im Bereich < 30 »m liegt.
  26. Mittel nach Anspruch 25, dadurch gekennzeichnet, daß die Korngröße des weichen Ätzkalks im Bereich < 16 »m liegt.
EP90312432A 1989-12-04 1990-11-14 Entschwefelungsmittel für geschmolzenes Metall Expired - Lifetime EP0431772B1 (de)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE3940024 1989-12-04
DE3940024 1989-12-04
DE4002284 1990-01-26
DE4002284A DE4002284A1 (de) 1989-12-04 1990-01-26 Mittel zum entschwefeln von eisenschmelzen

Publications (2)

Publication Number Publication Date
EP0431772A1 EP0431772A1 (de) 1991-06-12
EP0431772B1 true EP0431772B1 (de) 1995-04-12

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EP90312432A Expired - Lifetime EP0431772B1 (de) 1989-12-04 1990-11-14 Entschwefelungsmittel für geschmolzenes Metall

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EP (1) EP0431772B1 (de)
AT (1) ATE121140T1 (de)
DE (2) DE4002284A1 (de)
ES (1) ES2071043T3 (de)
FI (1) FI93971C (de)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6352570B1 (en) * 2000-04-10 2002-03-05 Rossborough Manufacturing Co., Lp Magnesium desulfurization agent
US20040126583A1 (en) * 2002-11-19 2004-07-01 Takashi Nakamura Foaming agent for manufacturing a foamed or porous metal

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB964299A (en) * 1962-05-29 1964-07-22 Foseco Int Treatment of molten iron
DE2157395A1 (de) * 1971-11-19 1973-05-24 Metallgesellschaft Ag Mittel zum behandeln von eisenlegierungsschmelzen
FR2456779A1 (fr) * 1979-05-15 1980-12-12 Sofrem Produit pour la desulfuration des fontes et aciers
DE3831831C1 (de) * 1988-09-20 1989-11-02 Skw Trostberg Ag, 8223 Trostberg, De

Also Published As

Publication number Publication date
DE69018584D1 (de) 1995-05-18
EP0431772A1 (de) 1991-06-12
ES2071043T3 (es) 1995-06-16
FI93971C (fi) 1995-06-26
DE69018584T2 (de) 1995-08-10
FI905990A (fi) 1991-06-05
ATE121140T1 (de) 1995-04-15
DE4002284A1 (de) 1991-06-06
FI905990A0 (fi) 1990-12-04
FI93971B (fi) 1995-03-15

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