EP0061012B1 - Procédé pour la fabrication d'agents de désulfuration de fonte et d'acier fondus - Google Patents

Procédé pour la fabrication d'agents de désulfuration de fonte et d'acier fondus Download PDF

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Publication number
EP0061012B1
EP0061012B1 EP82101428A EP82101428A EP0061012B1 EP 0061012 B1 EP0061012 B1 EP 0061012B1 EP 82101428 A EP82101428 A EP 82101428A EP 82101428 A EP82101428 A EP 82101428A EP 0061012 B1 EP0061012 B1 EP 0061012B1
Authority
EP
European Patent Office
Prior art keywords
weight
cao
calcium oxide
desulfurization
cac
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.)
Expired
Application number
EP82101428A
Other languages
German (de)
English (en)
Other versions
EP0061012A1 (fr
Inventor
Albert Braun
Willi Dr. Portz
Georg Dr. Strauss
Hans-Martin Dipl.-Ing. Delhey
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.)
Krupp Stahl AG
Hoechst AG
Original Assignee
Krupp Stahl AG
Hoechst 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 Krupp Stahl AG, Hoechst AG filed Critical Krupp Stahl AG
Priority to AT82101428T priority Critical patent/ATE9232T1/de
Publication of EP0061012A1 publication Critical patent/EP0061012A1/fr
Application granted granted Critical
Publication of EP0061012B1 publication Critical patent/EP0061012B1/fr
Expired legal-status Critical Current

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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
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/064—Dephosphorising; Desulfurising
    • C21C7/0645—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
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/02—Dephosphorising or desulfurising
    • C21C1/025—Agents used for dephosphorising or desulfurising

Definitions

  • the invention relates to a process for the preparation of a desulfurization agent for pig iron and steel melts based on a calcium carbide containing calcium oxide, in which a finely divided calcium oxide is introduced into a calcium carbide melt produced in a conventional manner, which already has a calcium oxide content of up to 45% by weight an excess of 3 to 15 wt .-%, based on the amount desired in the CaC 2 -CaO crystal mixture, then cools the resulting mixture under solidification to temperatures of 350 to 450 ° C, at these temperatures breaks down to grain sizes smaller than 150 mm , and separates the inevitable grain fraction smaller than 4 mm from the remaining product.
  • a method is already known from EP-A1-19087.
  • DE-A1-2907069 describes an agent for the desulfurization of molten metals, in particular pig iron and steel, based on CaC z / CaO, which consists of a CaC 2 / CaO crystal mixture produced in the melt flow and then comminuted with a CaC 2 content of 35 to 65 wt .-%, based on the amount of CaC 2 / CaO exists.
  • DE-B2-2 252 795 also specifies that the addition of calcium carbonate to the desulfurization agents has a gas-releasing effect and, by means of rising gas bubbles, promotes a uniform distribution of the desulfurization agent in all parts of the melt and at the same time accelerates the separation of the desulfurization products.
  • the same advantages, or even greater advantages in the presence of carbonate provide water-releasing additives, e.g. B. Ca (OH) 2 , to the desulfurizing agents.
  • the known desulfurization agents especially for use by the immersion lance method, first had to be ground as finely as possible. According to this, these mixtures meet the requirements, but are expensive in terms of both manufacture and use. Despite the fine grinding, relatively large amounts of the desulfurizing agents had to be added to achieve the desired degree of desulfurization.
  • EP-A1-31 552 relates to a means for desulfurizing metal melts, in particular steel and pig iron melts, on the basis of CaC 2 -CaO crystal mixtures obtained in the melt flow, which is characterized in that in the crystal mixture Part of the CaO is hydrated to Ca (OH).
  • the process for the preparation of this agent is characterized, inter alia, in that for the preparation of the end product, the 20 to 55% by weight calcium carbide, more than 45 to 80% by weight calcium oxide and also chemically bound to calcium oxide Water contains, in a present and customarily produced calcium carbide melt, which already has a calcium oxide content of up to 45% by weight, introduces finely divided calcium oxide in an excess of 3 to 15% by weight, based on the amount desired in the end product, then the resulting mixture cools to temperatures of 350 to 450 ° C under solidification, breaks down to grain sizes smaller than 150 mm at these temperatures, separates the resulting grain fraction smaller than 4 mm from the remaining product and the latter in the presence of air or nitrogen with a moisture content from 5 to 20 g / m 3 (at 1.013 bar and 273.15 K) by breaking and grinding at temperatures below 100 ° C to grain sizes smaller than 10 mm crushed.
  • the object of the present invention was to provide an economical process for producing a desulfurization agent which offers an improved degree of utilization.
  • the present invention be produced desulfurizing free carbon and carbonate contained and 2 7CaO-crystal mixture is hydrated, part of the CaO to Ca (OH) 2 in the CaC.
  • CaC 2 -CaO crystal mixtures with a proportion of 40 to 80% by weight CaO (corresponding to 20 to 60% by weight CaC 2 ), in particular 45 to 80% by weight CaO (corresponding to 20 to 55 % By weight of CaC 2 ) or 40 to 65% by weight of CaO) corresponding to 35 to 60% by weight of CaC 2 ).
  • the desulfurization agent to be produced according to the invention is preferably characterized in that it contains 1 to 6% by weight, preferably 2.5 to 3.5% by weight. contains water chemically bound to calcium oxide.
  • the desulfurization agents to be produced according to the invention preferably contain 0.5 to 8% by weight of free carbon (e.g. coke breeze, anthracite, graphite, carbon black) and 0.5 to 20% by weight. % Carbonates of calcium, magnesium or sodium.
  • CaO and CaC 2 crystallize as a crystal mixture in which the CaC 2 and CaO crystals are intertwined, specifically at the specified CaC 2 / CaO quantity ratio, with one lying in the area of the eutectic or shifted to the lime side hypoeutectic composition.
  • H 2 0 is added, part of the CaO in the crystal mixture reacts according to the equation without the CaC 2 grown together with the CaO crystals being substantially attacked by the H 2 0.
  • the grinding grains which consist of CaO-CaC 2 crystal growths in which some of the CaO crystals are hydrated, disintegrate at the prevailing temperatures above 800 ° C according to the following reaction equation
  • the grinding grain Because of the gas development at the reactive crystal interfaces, the grinding grain literally bursts with the release of lime, which is highly reactive in statu nascendi, and with enlargement of the CaO-CaC 2 crystal surfaces grown together in the grain. With an almost eutectic crystal structure, there is an ideally large reaction area.
  • the released reducing gases offer ideal conditions for the implementation of the CaO with the sulfur dissolved in the molten metal.
  • Such a desulfurization agent is particularly suitable for desulfurization processes in which the time for the desulfurization agent to react with the sulfur is very short.
  • This process includes the immersion lance process, in which the desulfurization agent should be converted as completely as possible by blowing desulfurization agents into a molten metal below its surface in the short time between the desulfurization agent exiting the melt and rising to the bath surface.
  • the desulfurization agent to be produced according to the invention is superior to the best known carbide-based mixtures in the desulfurization effect. Because of the intergranular gas reaction in the grinding grain, the conversion of CaC 2 to CaO and the resulting enlargement of the crystal surfaces are more effective, the gas development is much more uniform and less violent than with known desulfurization agents, e.g. B. according to DE-AS 2 252 795, which gas-releasing additives such as Ca (OH) z are mechanically mixed in from the beginning. Desulphurization therefore takes place more quietly and with less metal ejection, particularly in the open pan and the torpedo pan.
  • the material can be used in a coarser manner, so that expensive fine grinding can be dispensed with.
  • the use of the desulfurization agent to be produced according to the invention enables greater accuracy with regard to the respectively required final content due to its homogeneous composition.
  • the production costs for the agent to be produced according to the invention are considerably lower than for known agents based on carbide.
  • the process of the invention is characterized in particular in that free carbon and carbonate are added to the product, which has been broken down to grain sizes of less than 150 mm and freed from the grain fraction of less than 4 mm, and the mixture in the presence of air or nitrogen with a moisture content of 5 to 20 g / m 3 (at 1.013 bar and 273.15 K) by crushing and grinding at temperatures below 100 ° C, preferably from 10-50 ° C, crushed to grain sizes smaller than 10 mm, preferably 0.1 mm.
  • the calcium oxide which is introduced into the melt, is preheated to temperatures up to 2000 ° C., preferably up to 1100 ° C., and is introduced into the melt hot at these temperatures, it is possible to determine the CaO content in the Increase carbide to 80 wt .-%, the preheating is chosen higher, the higher the desired proportion of additionally dissolved calcium oxide should be between 40 and 80 wt .-%. This enables use in low-carbon pig iron and steel melts and also increases the desulfurization yield, based on calcium carbide.
  • the portions smaller than 4 mm which have been screened off after the preliminary crushing essentially consist of CaO and can be returned to the process as finely divided calcium oxide, where they serve as the starting product together with fresh CaO. It was not foreseeable for the person skilled in the art that, by screening off the portions falling less than 4 mm after the preliminary breaking, those portions which have no or only a slight desulfurization effect are removed from the product, and the effectiveness of the end product is considerably increased.
  • the product produced according to the invention can be ground much better than products obtained by known processes. This is particularly important because in some cases the product has to be used with a grain size of less than 0.1 mm.
  • Calcium carbide e.g. B. produced electrothermally, the lime-coke mixture in the Möller is set to a weight ratio of 100:40, which corresponds to a carbide with a CaO content of about 40 wt .-%.
  • CaO with a grain size of 3 to 8 mm and a Ca (OH) 2 - and CaC0 3 content of in each case less than 1% by weight is injected into the jet of the molten carbide tapped from the furnace into a crucible at such a speed and entered in such amounts that, until the crucible is filled, there is a total CaC 2 : CaO weight ratio of 43:57, which is an excess of 14% by weight CaO, based on the CaO desired in the CaC 2 -Ca0 crystal mixture - Contains 50% by weight.
  • the mixture is then cooled until the average temperature of the solidified carbide block is approximately 400 ° C., and the block is pre-crushed to sizes smaller than 150 mm.
  • the fractions smaller than 4 mm obtained during the preliminary crushing essentially contain the CaO used in excess, while the remaining product with grain sizes larger than 4 mm represents a crystal mixture of 50% by weight CaC 2 and 50% by weight CaO.
  • 850 kg of this CaC 2 -CaO crystal mixture are mixed with 100 kg limestone (grain size less than 1 mm) and 50 kg of coke breeze (grain size less than 3 mm) and while passing 1,500 m 3 / h of air with a moisture content of 10 g / m 3 (at 15 ° C) in a rotary mill with a throughput of 500 kg / h at 50 ° C to grain sizes smaller than 0.1 mm.
  • the screened grain fraction smaller than 4 mm is used together with fresh lime (CaO) as the starting product.
  • the product obtained contains 2% by weight of chemically bound water.
  • Example 2 The procedure is as in Example 1, with the changes that the CaO is preheated to a temperature of about 1100 ° C. and the amount of CaO is increased so that a total CaO content of 62.5 wt .-%, which corresponds to an excess of 4 wt .-%, based on the desired content in the finished end product of 60 wt .-% CaO.
  • 1800 kg of the product worked up and ground according to the invention are used to desulfurize a 300 t steel melt with a sulfur content of 0.02% by weight at 1,650 ° C.
  • the sulfur content of the melt is reduced to less than 0.005% by weight.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)

Claims (3)

1. Procédé de préparation d'un agent de désulfuration pour bains de fonte brute et d'acier à base de carbure de calcium contenant de l'oxyde de calcium, dans lequel on introduit dans un mélange fondu de carbure de calcium préparé de manière habituelle et présentant déjà une teneur en oxyde de calcium allant jusqu'à 45% en poids, de fines particules d'oxyde de calcium en excès de 3-15% en poids, par rapport à la quantité recherchée pour le mélange cristallin CaC2-CaO, on refroidit ensuite le mélange formé avec solidification à des températures de 350-450°C, on le concasse grossièrement à des températures en morceaux de dimensions inférieures à 150 mm et on sépare du produit restant la fraction granulométrique de moins de 4 mm qui se forme obligatoirement, caractérisé en ce que l'on mélange ce dernier avec du carbone libre et du carbonate et on fragmente le mélange en présence d'air ou d'azote d'une teneur en humidité de 5-20 g/m3 (sous 1,013 bar et à 273,15 K) par concassage et broyage à des températures inférieures à 100 °C, de préférence 10-50 °C, en particules de dimensions inférieures à 10 mm, de préférence inférieures à 0,1 mm.
2. Procédé selon la revendication 1, caractérisé en ce que l'agent de désulfuration contient 1-6% en poids, de préférence 2,5-3,5% en poids, d'eau chimiquement liée à l'oxyde de calcium.
3. Procédé selon la revendication 1 ou 2, caractérisé en ce que l'agent de désulfuration contient 0,5-8% en poids de carbone libre et 0,5-20% en poids de carbonate de calcium, de magnésium ou de sodium.
EP82101428A 1981-03-24 1982-02-25 Procédé pour la fabrication d'agents de désulfuration de fonte et d'acier fondus Expired EP0061012B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT82101428T ATE9232T1 (de) 1981-03-24 1982-02-25 Verfahren zur herstellung eines entschwefelungsmittels fuer roheisen- und stahlschmelzen.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3111510 1981-03-24
DE19813111510 DE3111510A1 (de) 1981-03-24 1981-03-24 Entschwefelungsgemisch und verfahren zu seiner herstellung

Publications (2)

Publication Number Publication Date
EP0061012A1 EP0061012A1 (fr) 1982-09-29
EP0061012B1 true EP0061012B1 (fr) 1984-09-05

Family

ID=6128140

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82101428A Expired EP0061012B1 (fr) 1981-03-24 1982-02-25 Procédé pour la fabrication d'agents de désulfuration de fonte et d'acier fondus

Country Status (10)

Country Link
US (1) US4395282A (fr)
EP (1) EP0061012B1 (fr)
JP (1) JPS57171611A (fr)
AT (1) ATE9232T1 (fr)
BR (1) BR8201621A (fr)
CA (1) CA1184385A (fr)
DD (1) DD202182A5 (fr)
DE (2) DE3111510A1 (fr)
ES (1) ES510768A0 (fr)
ZA (1) ZA821940B (fr)

Families Citing this family (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1240842A (fr) * 1984-05-16 1988-08-23 Heinrich Rellermeyer Methode et composition de desulfuration de la fonte grise en fusion
US4572737A (en) * 1984-06-27 1986-02-25 The Boc Group, Inc. Agents for the removal of impurities from a molten metal and a process for producing same
BR8606249A (pt) * 1985-12-17 1987-09-29 Sueddeutsche Kalkstickstoff Composicao finamente granulada para a dessulfuracao de ferro fundido e processo para sua preparacao
DE3908071A1 (de) * 1989-03-13 1990-09-20 Hoechst Ag Mittel und verfahren zum entschwefeln von metallschmelzen
US5358550A (en) * 1992-10-26 1994-10-25 Rossborough Manufacturing Company Desulfurization agent
US5407459A (en) * 1993-09-23 1995-04-18 Alcan International Limited Process for the preparation of calcium aluminates from aluminum dross residues
AT406690B (de) * 1994-12-09 2000-07-25 Donau Chemie Ag Mittel zur behandlung von roheisen- und gusseisenschmelzen zum zweck der entschwefelung
US6238633B1 (en) 1997-06-30 2001-05-29 Aluminum Waste Technology, Inc. Process for preparing calcium aluminate from aluminum dross
US6352570B1 (en) 2000-04-10 2002-03-05 Rossborough Manufacturing Co., Lp Magnesium desulfurization agent
US6372014B1 (en) 2000-04-10 2002-04-16 Rossborough Manufacturing Co. L.P. Magnesium injection agent for ferrous metal
US6770115B2 (en) * 2002-10-18 2004-08-03 Remacor, Inc. Process for magnesium granules
US6989040B2 (en) * 2002-10-30 2006-01-24 Gerald Zebrowski Reclaimed magnesium desulfurization agent
US7731778B2 (en) * 2006-03-27 2010-06-08 Magnesium Technologies Corporation Scrap bale for steel making process
US20080196548A1 (en) * 2007-02-16 2008-08-21 Magnesium Technologies Corporation Desulfurization puck

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH428820A (fr) * 1963-12-12 1967-01-31 Tech Entwicklung Und Verwertun Produit d'affinage de l'acier
US3197306A (en) * 1964-08-31 1965-07-27 Dow Chemical Co Method for treating ferrous metals
DE1758250B1 (de) * 1968-04-29 1971-10-28 Sueddeutsche Kalkstickstoff Mittel zum Entschwefeln von Eisenschmelzen
DE2252795C3 (de) * 1972-10-27 1982-09-09 Skw Trostberg Ag, 8223 Trostberg Entschwefelungsmittel für Roheisen- und Ferrolegierungsschmelzen
DE2326539C3 (de) * 1973-05-24 1975-11-13 Sueddeutsche Kalkstickstoff-Werke Ag, 8223 Trostberg Verfahren zur Herstellung eines Entschwefelungsgemisches für Eisenschmelzen aus Calciumcarbid und mindestens einem wasserhaltigen Stoff
DE2741588C2 (de) * 1977-09-15 1985-02-07 Skw Trostberg Ag, 8223 Trostberg Mittel zum Entschwefeln von Eisenschmelzen
DE2907069C3 (de) * 1979-02-23 1981-12-10 Krupp Stahl Ag, 4630 Bochum Mittel zur Entschwefelung von Metallschmelzen
DE2919324A1 (de) * 1979-05-14 1980-12-04 Hoechst Ag Entschweflungsmittel fuer roheisen- und stahlschmelzen sowie ein verfahren zu ihrer herstellung
DE2920353A1 (de) * 1979-05-19 1980-11-27 Hoechst Ag Verfahren zur herstellung von entschweflungsmitteln fuer roheisen- oder stahlschmelzen
ES497686A0 (es) * 1979-12-29 1981-11-01 Hoechst Ag Procedimiento para la preparacion de un agente para la de- sulfuracion de masas fundidas metalicas
DE2952686A1 (de) * 1979-12-29 1981-07-02 Hoechst Ag, 6230 Frankfurt Verfahren zur herstellung von entschwefelungsmitteln fuer roheisen- oder stahlschmelzen

Also Published As

Publication number Publication date
ES8302103A1 (es) 1983-02-01
JPH0152446B2 (fr) 1989-11-08
JPS57171611A (en) 1982-10-22
ATE9232T1 (de) 1984-09-15
DD202182A5 (de) 1983-08-31
US4395282A (en) 1983-07-26
ZA821940B (en) 1983-02-23
DE3260643D1 (en) 1984-10-11
EP0061012A1 (fr) 1982-09-29
CA1184385A (fr) 1985-03-26
DE3111510A1 (de) 1982-10-07
ES510768A0 (es) 1983-02-01
BR8201621A (pt) 1983-02-16

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