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EP0042033B1 - Desulfurising agent - Google Patents

Desulfurising agent Download PDF

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Publication number
EP0042033B1
EP0042033B1 EP81101764A EP81101764A EP0042033B1 EP 0042033 B1 EP0042033 B1 EP 0042033B1 EP 81101764 A EP81101764 A EP 81101764A EP 81101764 A EP81101764 A EP 81101764A EP 0042033 B1 EP0042033 B1 EP 0042033B1
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EP
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Prior art keywords
diamide lime
calcium
treated
diamide
lime
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
EP81101764A
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German (de)
French (fr)
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EP0042033A1 (en
Inventor
Alfred Dr. Freissmuth
Werner Dr. Gmöhling
Walter Meichsner
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Evonik Operations GmbH
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SKW Trostberg AG
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Priority to AT81101764T priority Critical patent/ATE13694T1/en
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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

  • Desulphurization agents for the iron and steel industry based on calcium carbide and diamide lime have been known for some years (cf. DE-AS 1 758 250) and there has been no lack of attempts to obtain these agents by varying the ratio of calcium carbide / diamide lime (DE- AS 2 500 497) or by additives (DE-OS 2 741 588) to improve their effectiveness.
  • the object of the present invention was therefore to provide a desulfurization agent based on calcium carbide and diamide lime, with which the disadvantages described can be eliminated and improved economy can be achieved.
  • this object is achieved by a desulfurizing agent based on calcium carbide and diamide lime, characterized in that it consists of 30 to 90% by weight of calcium carbide and the remainder consists of a diamide lime after-treated by flotation or air classifying, the post-treated diamide lime 18 to 55%. contains free carbon and 5 to 10% residual impurities such as calcium oxide, calcium hydroxide, iron oxide, aluminum oxide and silicon dioxide.
  • Diamide lime is a mixture consisting essentially of calcium carbonate and carbon. Such mixtures occur, for example, in the case of the dicyandiamide products, in the course of which aqueous calcium nitrogen suspensions are treated with carbon dioxide, and then contain about 70 to 85% calcium carbonate and about 8 to 12% carbon in addition to impurities, in particular iron oxide, aluminum oxide and silicon dioxide.
  • the precipitated diamide lime is either subjected to flotation or is first dried and then subjected to an air separation process.
  • the flotation and the wind sifting can be carried out in a known manner and using the customary equipment (see, for example, Ullmann's Encyklopadie der Technischen Chemie, Verlag Chemie, Weinheim, 4th edition, volume 2, pages 110 to 142 and 57 to 69).
  • the post-treated diamide lime contains about 17 to 36% CO 2, corresponding to 38 to 82% calcium carbonate, 18 to 55% free carbon and about 5 to 10% residual impurities such as calcium oxide, calcium hydroxide, iron oxide, aluminum oxide and silicon dioxide .
  • an aftertreated diamide lime can also be mixed with an untreated diamide lime, e.g. B. in a weight ratio of 50/50, and this «blend used to produce the mixture according to the invention.
  • a diamide lime with 18 to 40%, in particular 25 to 30%, free carbon is preferably used.
  • Such diamide lime has e.g. B. the following analysis values: 25 to 30% free carbon, 28 to 30% CO 2 corresponding to 64 to 68% calcium carbonate, and 5 to 10% of calcium oxide, calcium hydroxide and impurities such as iron oxide, aluminum oxide and silicon dioxide.
  • the aftertreatment enriches in particular the carbon content, the calcium carbonate particles adhering to the carbon and the very fine content of the diamide lime. While the untreated diamide lime has an average particle size of approx. 35 ⁇ m, where 10% ⁇ approx. 75 ⁇ m and 10% ⁇ approx. 10 ⁇ m, these data have been shifted to significantly smaller particle sizes for the after-treated diamide lime: the average particle size of an after-treated diamide lime with about 40% carbon is only 5 ⁇ m, with 10% above about 15 ⁇ m and 10% below about 2 ⁇ m. Depending on the intensity of the after-treatment, these values can be shifted up or down.
  • the desulfurization mixtures according to the invention are prepared by combining calcium carbide with the dried post-treated diamide lime together in a mill, e.g. B. ground in a tube mill.
  • the grinding process in particular the duration of the grinding, is of course of great importance for the production of a mixture which is optimal with regard to flowability and desulfurization.
  • the minimum grinding time is usually about 5 minutes, and the time required to achieve optimal results is usually between 10 and 30 minutes.
  • the mixture according to the invention can also contain other conventional additives, such as. B. finely divided silicon dioxide to further improve the flowability, or else additives to carbon, z. B. in the form of fat, hard coal or flame coal, anthracite, and in particular in the form of graphite.
  • additives such as. B. finely divided silicon dioxide to further improve the flowability, or else additives to carbon, z. B. in the form of fat, hard coal or flame coal, anthracite, and in particular in the form of graphite.
  • mixtures according to the invention are surprisingly considerably more effective than the mixtures prepared with untreated diamide lime (with the same amount of carbon dioxide bound as calcium carbonate) and, also thanks to the uniformly good flowability, lead to readily reproducible results.
  • the application therefore also relates to the use of the agents according to the invention for the desulfurization of molten iron, such as pig iron, cast iron and steel melts.
  • the mixture according to the invention contains more carbon from the diamide lime and - with the same amount of carbon dioxide bound as calcium carbonate - less calcium carbide than the corresponding mixture produced with untreated diamide lime.
  • Calcium carbide is the active substance that causes desulfurization. It is therefore surprising that, despite its reduced calcium carbide content, 1 kg of desulfurization mixture according to the invention desulfurizes better than 1 kg of calcium carbide and untreated diamide lime mixture.
  • the post-treated diamide lime used in mixture 4) has the following analytical values: 25% free carbon, 30% CO 2 corresponding to 68% calcium carbonate and 7% calcium oxide, calcium hydroxide and impurities such as iron oxide, aluminum oxide and silicon dioxide. Average particle size 15 4 m, 10%> 35 ⁇ m, 10% ⁇ 5 ⁇ m.

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  • 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)
  • Treating Waste Gases (AREA)
  • Processing Of Solid Wastes (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Filtering Of Dispersed Particles In Gases (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)

Abstract

The present invention provides a desulphurizing agent, especially for iron melts, based upon calcium carbide and diamide lime, wherein it contains a diamide lime which has been post-treated by flotation or air sifting. The diamide lime used preferably contains 18 to 40% of free carbon.

Description

Entschwefelungsmittel für die Eisen- und Stahlindustrie auf Basis von Calciumcarbid und Diamidkalk sind seit einigen Jahren bekannt (vgl. DE-AS 1 758 250), und es hat nicht an Versuchen gefehlt, diese Mittel durch Variation des Verhältnisses von Calciumcarbid/Diamidkalk (DE-AS 2 500 497) oder durch Zusätze (DE-OS 2 741 588) in ihrer Effektivität zu verbessern.Desulphurization agents for the iron and steel industry based on calcium carbide and diamide lime have been known for some years (cf. DE-AS 1 758 250) and there has been no lack of attempts to obtain these agents by varying the ratio of calcium carbide / diamide lime (DE- AS 2 500 497) or by additives (DE-OS 2 741 588) to improve their effectiveness.

Trotz aller Verbesserungen hinsichtlich der Wirksamkeit dieser Entschwefelungsmittel wurden aber immer wieder Fehlchargen erhalten, d. h. Roheisenschmelzen, die trotz gleicher Gemischzusammensetzung des Entschwefelungsmittels und unveränderter Einblasbedingungen nach der Behandlung viel zu hohe Endschwefelgehalte aufwiesen.Despite all the improvements in the effectiveness of these desulfurizing agents, false batches have repeatedly been obtained. H. Pig iron melts which, despite the same mixture composition of the desulfurization agent and unchanged blowing conditions after the treatment, had much too high final sulfur contents.

Es wurde beobachtet, daß mit den bisher bekanntgewordenen technischen Vorrichtungen die bisher bekannten Entschwefelungsgemische nicht immer mit befriedigender Gleichmäßigkeit in die Roheisenschmelze eingetragen werden. Bei solch stoßweiser Förderung des Entschwefelungsmittels wird das Flüssigeisen schubweise mit Entschwefelungsmittel in Berührung gebracht. Dadurch gelangen bestimmte Bereiche der Schmelze mit überschüssigem Entschwefelungsmittel in Kontakt, so daß es, ohne seine Wirkung zu entfalten, lediglich den Schlackenanteil vermehrt. Für den Erfolg der Entschwefelungsbehandlung ist es daher von entscheidender Bedeutung, daß die Roheisenschmelze während der gesamten Behandlungsdauer gleichmäßig mit dem Entschwefelungsmittel in Berührung gebracht wird. Dieses Problem kann durch apparative Vorrichtungen allein nicht gelöst werden, sondern erfordert vor allem auch eine gute und gleichmäßige Fließfähigkeit des Entschwefelungsmittels. Darüberhinaus war es das Bestreben, die Wirtschaftlichkeit bei Einsatz der Entschwefelungsmittel zu verbessern, d. h. die Einsatzmenge bei gleich gutem Resultat zu verringern.It has been observed that the previously known technical devices do not always introduce the previously known desulfurization mixtures into the pig iron melt with satisfactory uniformity. When the desulfurizing agent is pumped in this way, the liquid iron is brought into contact with the desulfurizing agent in batches. As a result, certain areas of the melt come into contact with excess desulfurizing agent, so that it only increases the amount of slag without developing its effect. For the success of the desulfurization treatment it is therefore of crucial importance that the pig iron melt is brought into constant contact with the desulfurization agent during the entire treatment period. This problem cannot be solved by apparatus alone, but above all requires good and uniform flowability of the desulfurization agent. In addition, efforts have been made to improve the economy when using the desulfurization agents, i. H. to reduce the amount used with the same good result.

Aufgabe der vorliegenden Erfindung war es deshalb, ein Entschwefelungsmittel auf der Basis von Caiciumcarbid und Diamidkalk bereitzustellen, mit dem die geschilderten Nachteile behoben und eine verbesserte Wirtschaftlichkeit erreicht werden kann.The object of the present invention was therefore to provide a desulfurization agent based on calcium carbide and diamide lime, with which the disadvantages described can be eliminated and improved economy can be achieved.

Erfindungsgemäß wird diese Aufgabe gelöst durch ein Entschwefelungsmittel auf der Basis von Calciumcarbid und Diamidkalk, dadurch gekennzeichnet, daß es aus 30 bis 90 Gew.-% Calciumcarbid und Rest aus einem durch Flotation oder Windsichten nachbehandelten Diamidkalk besteht, wobei der nachbehandelte Diamidkalk 18 bis 55 % freien Kohlenstoff und 5 bis 10 % restliche Verunreinigungen wie Calciumoxid, Calciumhydroxid, Eisenoxid, Aluminiumoxid und Siliciumdioxid enthält.According to the invention, this object is achieved by a desulfurizing agent based on calcium carbide and diamide lime, characterized in that it consists of 30 to 90% by weight of calcium carbide and the remainder consists of a diamide lime after-treated by flotation or air classifying, the post-treated diamide lime 18 to 55%. contains free carbon and 5 to 10% residual impurities such as calcium oxide, calcium hydroxide, iron oxide, aluminum oxide and silicon dioxide.

Diamidkalk ist ein im wesentlichen aus Calciumcarbonat und Kohlenstoff bestehendes Gemisch. Solche Gemische fallen beispielsweise bei den Dicyandiamidprodukten an, in deren Verlauf wäßrige Kalkstickstoffsuspensionen mit Kohlendioxid behandelt werden, und enthalten dann etwa 70 bis 85 % Calciumcarbonat und etwa 8 bis 12 % Kohlenstoff neben Verunreinigungen, insbesondere Eisenoxid, Aluminiumoxid und Siliziumdioxid. Zur Nachbehandlung wird der ausgefällte Diamidkalk entweder einer Flotation unterworfen oder aber zunächst getrocknet und dann einem Windsichtvorgang unterworfen. Die Flotation und die Windsichtung können dabei auf bekannte Weise und mit den dafür üblichen Apparaturen erfolgen (vgl. z. B. Ullmanns Encyklopädie der Technischen Chemie, Verlag Chemie, Weinheim, 4. Auflage, Band.2, Seiten 110 bis 142 und 57 bis 69).Diamide lime is a mixture consisting essentially of calcium carbonate and carbon. Such mixtures occur, for example, in the case of the dicyandiamide products, in the course of which aqueous calcium nitrogen suspensions are treated with carbon dioxide, and then contain about 70 to 85% calcium carbonate and about 8 to 12% carbon in addition to impurities, in particular iron oxide, aluminum oxide and silicon dioxide. For the aftertreatment, the precipitated diamide lime is either subjected to flotation or is first dried and then subjected to an air separation process. The flotation and the wind sifting can be carried out in a known manner and using the customary equipment (see, for example, Ullmann's Encyklopadie der Technischen Chemie, Verlag Chemie, Weinheim, 4th edition, volume 2, pages 110 to 142 and 57 to 69).

Je nach Art und Dauer der Nachbehandlung enthält der nachbehandelte Diamidkalk etwa 17 bis 36 % CO2 entsprechend 38 bis 82 % Calciumcarbonat, 18 bis 55 % freien Kohlenstoff und ca. 5 bis 10 % restliche Verunreinigungen wie Calciumoxid, Calciumhydroxid, Eisenoxid, Aluminiumoxid und Siliziumdioxid. Es kann aber auch ein nachbehandelter Diamidkalk mit einem unbehandelten Diamidkalk gemischt werden, z. B. im Gewichtsverhältnis 50/50, und dieser « Verschnitt zur Herstellung des erfindungsgemäßen Gemisches verwendet werden. Vorzugsweise wird ein Diamidkalk mit 18 bis 40 %, insbesondere 25 bis 30 % freiem Kohlenstoff eingesetzt. Ein solcher Diamidkalk weist z. B. die folgenden Analysenwerte auf : 25 bis 30 % freien Kohlenstoff, 28 bis 30 % CO2entsprechend 64 bis 68 % Calciumcarbonat, sowie 5 bis 10 % an Calciumoxid, Calciumhydroxid und Verunreinigungen, wie Eisenoxid, Aluminiumoxid und Siliziumdioxid.Depending on the type and duration of the aftertreatment, the post-treated diamide lime contains about 17 to 36% CO 2, corresponding to 38 to 82% calcium carbonate, 18 to 55% free carbon and about 5 to 10% residual impurities such as calcium oxide, calcium hydroxide, iron oxide, aluminum oxide and silicon dioxide . However, an aftertreated diamide lime can also be mixed with an untreated diamide lime, e.g. B. in a weight ratio of 50/50, and this «blend used to produce the mixture according to the invention. A diamide lime with 18 to 40%, in particular 25 to 30%, free carbon is preferably used. Such diamide lime has e.g. B. the following analysis values: 25 to 30% free carbon, 28 to 30% CO 2 corresponding to 64 to 68% calcium carbonate, and 5 to 10% of calcium oxide, calcium hydroxide and impurities such as iron oxide, aluminum oxide and silicon dioxide.

Durch die Nachbehandlung werden besonders der Kohlenstoffanteil, die am Kohlenstoff haftenden Calciumcarbonat-Teilchen und der Feinstanteil des Diamidkalkes angereichert. Während der unbehandelte Diamidkalk eine mittlere Teilchengröße von etwa 35 µm aufweist, wobei 10 % < ca. 75 µm und 10 % < ca. 10 µm sind, sind diese Daten beim nachbehandelten Diamidkalk zu wesentlich kleineren Teilchengrößen verschoben : die mittlere Teilchengröße eines nachbehandelten Diamidkalkes mit etwa 40 % Kohlenstoff beträgt nur 5 µm, wobei 10 % über ca. 15 µm und 10 % unter ca. 2 µm liegen. Je nach Intensität der Nachbehandlung können diese Werte nach oben oder unten verschoben sein.The aftertreatment enriches in particular the carbon content, the calcium carbonate particles adhering to the carbon and the very fine content of the diamide lime. While the untreated diamide lime has an average particle size of approx. 35 µm, where 10% <approx. 75 µm and 10% <approx. 10 µm, these data have been shifted to significantly smaller particle sizes for the after-treated diamide lime: the average particle size of an after-treated diamide lime with about 40% carbon is only 5 µm, with 10% above about 15 µm and 10% below about 2 µm. Depending on the intensity of the after-treatment, these values can be shifted up or down.

Die erfindungsgemäßen Entschwefelungsgemische werden hergestellt, indem man Calciumcarbid mit dem getrockneten nachbehandelten Diamidkalk zusammen in einer Mühle, z. B. in einer Rohrmühle, vermahlt.The desulfurization mixtures according to the invention are prepared by combining calcium carbide with the dried post-treated diamide lime together in a mill, e.g. B. ground in a tube mill.

Die durch Vermahlen von Calciumcarbid mit nachbehandeltem Diamidkalk hergestellten erfindungsgemäßen Gemische weichen in ihrer Feinheit auch wesentlich von dem mit unbehandeltem Diamidkalk hergestellten Entschwefelungsmittel ab :

  • Der mittlere Teilchendurchmesser eines fertig-gemahlenen Gemisches aus 60 % Calciumcarbid und 40 % nachbehandeltem Diamidkalk liegt bei etwa 20 bis 35 µm, während er beim entsprechenden, mit unbehandeltem Diamidkalk hergestellten Gemisch etwa 45 bis 50 µm beträgt. 10 % der Teilchen sind beim erfindungsgemäßen Gemisch größer als etwa 70 µm und 10 % kleiner als etwa 3 µm. Beim bisher bekannten Entschwefelungsmittel aus Calciumcarbid und nicht nachbehandeltem Diamidkalk liegen 80 % der Teilchen zwischen etwa 100 und etwa 5 µm (10 % > 100 µm und 10 % < 5 µm).
The fineness of the mixtures according to the invention produced by grinding calcium carbide with post-treated diamide lime also differ significantly from the desulfurization agent produced with untreated diamide lime:
  • The average particle diameter of a ready-milled mixture of 60% calcium carbide and 40% post-treated diamide lime is about 20 to 35 µm, while it is the same with untreated diamide lime mixture is about 45 to 50 microns. 10% of the particles in the mixture according to the invention are larger than approximately 70 μm and 10% smaller than approximately 3 μm. In the previously known desulphurization agent made of calcium carbide and untreated diamide lime, 80% of the particles are between about 100 and about 5 µm (10%> 100 µm and 10% <5 µm).

Für die Herstellung eines hinsichtlich Fließfähigkeit und Entschwefelungswirkung optimalen Gemisches ist selbstverständlich auch der Mahlvorgang, insbesondere die Dauer der Mahlung, von großer Bedeutung. Die Mindestmahldauer beträgt dabei normalerweise etwa 5 min, und die zur Erzielung optimaler Ergebnisse erforderliche Dauer liegt meist zwischen 10 und 30 min.The grinding process, in particular the duration of the grinding, is of course of great importance for the production of a mixture which is optimal with regard to flowability and desulfurization. The minimum grinding time is usually about 5 minutes, and the time required to achieve optimal results is usually between 10 and 30 minutes.

Das erfindungsgemäße Gemisch kann auch noch weitere übliche Zusätze enthalten, wie z. B. feinverteiltes Siliziumdioxid zur weiteren Verbesserung der Fließfähigkeit, oder aber auch Zusätze an Kohlenstoff, z. B. in Form von Fett-, Stein- oder Flammkohle, Anthrazit, und insbesondere in Form von Graphit.The mixture according to the invention can also contain other conventional additives, such as. B. finely divided silicon dioxide to further improve the flowability, or else additives to carbon, z. B. in the form of fat, hard coal or flame coal, anthracite, and in particular in the form of graphite.

Es hat sich nun gezeigt, daß die erfindungsgemäßen Gemische überraschenderweise wesentlich wirksamer sind als die mit unbehandeltem Diamidkalk hergestellten Gemische (bei gleicher Menge von als Calciumcarbonat gebundenem Kohlendioxid), und, auch dank der gleichmäßig guten Fließfähigkeit, zu gut reproduzierbaren Ergebnissen führen.It has now been found that the mixtures according to the invention are surprisingly considerably more effective than the mixtures prepared with untreated diamide lime (with the same amount of carbon dioxide bound as calcium carbonate) and, also thanks to the uniformly good flowability, lead to readily reproducible results.

Besonders bewährt haben sich für die Behandlung von Roheisenschmelzen Mittel folgender Zusammensetzung :

  • a) wenn sie in Torpedopfannen erfolgt :
    • 30 bis 70 Gew.-% Calciumcarbid, Rest Diamidkalk,
  • b) wenn sie in offenen Pfannen erfolgt :
    • 70 bis 90 Gew.-% Calciumcarbid, Rest Diamidkalk.
Agents of the following composition have proven particularly useful for the treatment of pig iron melts:
  • a) if it is done in torpedo pans:
    • 30 to 70% by weight calcium carbide, remainder diamide lime,
  • b) if it is done in open pans:
    • 70 to 90% by weight calcium carbide, the rest diamide lime.

Gegenstand der Anmeldung ist deshalb auch die Verwendung der erfindungsgemäßen Mittel zum Entschwefeln von Eisenschmelzen, wie Roheisen-, Gußeisen- und Stahlschmelzen.The application therefore also relates to the use of the agents according to the invention for the desulfurization of molten iron, such as pig iron, cast iron and steel melts.

Das erfindungsgemäße Gemisch enthält mehr Kohlenstoff aus dem Diamidkalk und - bei gleicher Menge von als Calciumcarbonat gebundenem Kohlendioxid - weniger Calciumcarbid als das entsprechende, mit unbehandeltem Diamidkalk hergestellte Gemisch. Calciumcarbid ist die aktive Substanz, die die Entschwefelung bewirkt. Es ist deshalb überraschend, daß 1 kg erfindungsgemäßes Entschwefelungsgemisch trotz seines verringerten Gehaltes an Calciumcarbid besser entschwefelt als 1 kg Gemisch aus Calciumcarbid und unbehandeltem Diamidkalk.The mixture according to the invention contains more carbon from the diamide lime and - with the same amount of carbon dioxide bound as calcium carbonate - less calcium carbide than the corresponding mixture produced with untreated diamide lime. Calcium carbide is the active substance that causes desulfurization. It is therefore surprising that, despite its reduced calcium carbide content, 1 kg of desulfurization mixture according to the invention desulfurizes better than 1 kg of calcium carbide and untreated diamide lime mixture.

Die wesentlich bessere Wirkung beruht aber nicht allein auf dem höheren Gehalt an Kohlenstoff im Gemisch (vgl. DE-OS 27 41 588). Denn Versuche mit zum Vergleich herangezogenen Gemischen aus Calciumcarbid und unbehandeltem Diamidkalk mit Zusätzen von Kohlenstoff in Form von Graphit, Petrolkoks oder Flammkohle haben überraschenderweise ergeben, daß die verbessernde Wirkung des nachbehandelten Diamidkalkes auf das Entschwefelungsgemisch die anderen Zusätze übertrifft. Diese Befunde werden im nachfolgenden Beispiel erläutert :The much better effect is not based solely on the higher carbon content in the mixture (cf. DE-OS 27 41 588). Experiments with comparative mixtures of calcium carbide and untreated diamide lime with additions of carbon in the form of graphite, petroleum coke or flame coal have surprisingly shown that the improving effect of the post-treated diamide lime on the desulfurization mixture exceeds the other additions. These findings are explained in the following example:

Beispielexample

Es wurden Gemische aus

Figure imgb0001
hergestellt und jeweils 2 bis 4 Wochen lang an einer Entschwefelungsanlage eingesetzt und in ihrer Entschwefelungswirkung verglichen. Das Entschwefelungsmittel wurde mit getrockneter Luft in einem Staubgutverteiler aufgelockert und mit etwa 4 bis 10 NI Luft pro kg Entschwefelungsmittel durch eine Tauchlanze in eine mit ca. 150 t flüssigem Roheisen (Ausgangsschwefelgehalt ca. 0,050 %) gefüllte Torpedopfanne eingeblasen.Mixtures were made
Figure imgb0001
 produced and used for 2 to 4 weeks at a desulfurization plant and compared in their desulfurization effect. The desulphurisation agent was loosened up with dried air in a dust distributor and blown into a torpedo pan filled with approx. 150 t liquid pig iron (starting sulfur content approx. 0.050%) with approx. 4 to 10 NI air per kg desulphurisation agent.

Der im Gemisch 4) verwendete nachbehandelte Diamidkalk besitzt die folgenden Analysenwerte : 25% freier Kohlenstoff, 30 % CO2 entsprechend 68 % Calciumcarbonat und 7 % Calciumoxid, Calciumhydroxid und Verunreinigungen wie Eisenoxid, Aluminiumoxid und Siliziumdioxid. Mittlere Teilchengröße 15 4m, 10 % > 35 µm, 10 % < 5 µm.The post-treated diamide lime used in mixture 4) has the following analytical values: 25% free carbon, 30% CO 2 corresponding to 68% calcium carbonate and 7% calcium oxide, calcium hydroxide and impurities such as iron oxide, aluminum oxide and silicon dioxide. Average particle size 15 4 m, 10%> 35 µm, 10% <5 µm.

Der Vergleich wurde in der Weise durchgeführt, daß die für die Behandlung erforderliche Menge an Entschwefelungsmittel jeweils nach der gleichen Formel errechnet wurde, wie sie für das übliche Entschwefelungsmittel verwendet wird. Es wurden also in allen Versuchsreihen die gleichen Mengen an Entschwefelungsmittel eingesetzt und danach aus dem Ergebnis der Entschwefelungsbehandlung auf die Wirksamkeit des geprüften Mittels geschlossen. Dabei zeigte sich, daß das erfindungsgemäBe Gemisch 4) allen übrigen Gemischen deutlich überlegen ist :

  • Mit den Gemischen 1) bis 3) wurden Endgehalte von 0,015 bis 0,013 % Schwefel erzielt, mit dem erfindungsgemäßen Gemisch 4) dagegen ein Endgehalt von 0,011 % Schwefel.
The comparison was carried out in such a way that the amount of desulfurizing agent required for the treatment was calculated according to the same formula as that used for the conventional desulfurizing agent. The same amounts of desulfurization agent were therefore used in all the test series and the effectiveness of the tested agent was then deduced from the result of the desulfurization treatment. It was found that the Mixture 4) is clearly superior to all other mixtures:
  • With the mixtures 1) to 3), final contents of 0.015 to 0.013% sulfur were achieved, with the mixture 4) according to the invention, however, a final content of 0.011% sulfur.

Claims (2)

1. Desulphurising agent based on calcium carbide and diamide lime, characterised in that it consists of 30 to 90 wt.% of calcium carbide and the remainder of a diamide lime after-treated by flotation or air sifting, whereby the after-treated diamide lime contains 18 to 55 % of free carbon and 5 to 10 % of residual impurities, such as calcium oxide, calcium hydroxide, iron oxide, aluminium oxide or silicon dioxide.
2. Desulphurising agent according to claim 1, characterised in that the after-treated diamide lime contains up to 50 wt.% of untreated diamide lime.
EP81101764A 1980-06-18 1981-03-10 Desulfurising agent Expired EP0042033B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT81101764T ATE13694T1 (en) 1980-06-18 1981-03-10 DESULPHURIZATION AGENT.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19803022752 DE3022752A1 (en) 1980-06-18 1980-06-18 DESULFURING AGENT
DE3022752 1980-06-18

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EP0042033A1 EP0042033A1 (en) 1981-12-23
EP0042033B1 true EP0042033B1 (en) 1985-06-05

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EP81101764A Expired EP0042033B1 (en) 1980-06-18 1981-03-10 Desulfurising agent

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US (1) US4430118A (en)
EP (1) EP0042033B1 (en)
JP (1) JPS5726116A (en)
AT (1) ATE13694T1 (en)
CA (1) CA1161650A (en)
DE (2) DE3022752A1 (en)
ES (1) ES8305047A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19724913A1 (en) * 1997-06-12 1998-12-17 Almamet Gmbh Means for the fluorine-free treatment of molten steel in the ladle, process for its preparation and its use

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58204119A (en) * 1982-05-25 1983-11-28 Nippon Carbide Ind Co Ltd Desulfurizing agent for molten iron
JPS5953611A (en) * 1982-09-22 1984-03-28 Kawasaki Steel Corp Desulfurizing method of molten iron
JPS6169911A (en) * 1985-09-06 1986-04-10 Kawasaki Steel Corp Desulfurization agent for molten iron and its manufacturing method
BR8606249A (en) * 1985-12-17 1987-09-29 Sueddeutsche Kalkstickstoff FINALLY GRANULATED COMPOSITION FOR THE DESULFURATION OF CAST IRON AND PROCESS FOR ITS PREPARATION
CA1286506C (en) * 1987-02-13 1991-07-23 William Kevin Kodatsky Method of desulfurizing iron
US5002733A (en) * 1989-07-26 1991-03-26 American Alloys, Inc. Silicon alloys containing calcium and method of making same
JPH0731691Y2 (en) * 1992-03-16 1995-07-26 俊雄 今中 Patch
BR0111679B1 (en) * 2000-06-14 2010-06-29 manufacturing process of a hot metal desulphurizing agent, hot metal desulphurizing agent and low sulfur hot metal manufacturing process.
US6989040B2 (en) * 2002-10-30 2006-01-24 Gerald Zebrowski Reclaimed magnesium desulfurization agent

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1758250B1 (en) * 1968-04-29 1971-10-28 Sueddeutsche Kalkstickstoff Agent for the desulphurisation of iron melts
DE2741588C2 (en) * 1977-09-15 1985-02-07 Skw Trostberg Ag, 8223 Trostberg Agent for desulphurising molten iron
FR2432550A1 (en) * 1978-08-04 1980-02-29 Sueddeutsche Kalkstickstoff PROCESS FOR THE MANUFACTURE OF AN EASILY FLOWABLE PULVERULATED DESULFURIZATION MIXTURE
DE2835872C3 (en) * 1978-08-16 1981-02-05 Skw Trostberg Ag, 8223 Trostberg Process for reducing dust and flame nuisance when handling the slag after hot metal desulphurisation by means of a desulphurisation mixture and a desulphurisation mixture
JPS56163213A (en) 1980-05-20 1981-12-15 Nippon Carbide Ind Co Ltd Desulfurizer powder composition for molten iron

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19724913A1 (en) * 1997-06-12 1998-12-17 Almamet Gmbh Means for the fluorine-free treatment of molten steel in the ladle, process for its preparation and its use

Also Published As

Publication number Publication date
EP0042033A1 (en) 1981-12-23
US4430118A (en) 1984-02-07
ES501368A0 (en) 1983-04-01
ATE13694T1 (en) 1985-06-15
CA1161650A (en) 1984-02-07
ES8305047A1 (en) 1983-04-01
JPS5726116A (en) 1982-02-12
DE3170808D1 (en) 1985-07-11
DE3022752A1 (en) 1982-01-14

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