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EP0164592A1 - Fine-grained desulfurization agent forron melts, and process for the desulfurization of molten pig iron - Google Patents

Fine-grained desulfurization agent forron melts, and process for the desulfurization of molten pig iron Download PDF

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Publication number
EP0164592A1
EP0164592A1 EP85105870A EP85105870A EP0164592A1 EP 0164592 A1 EP0164592 A1 EP 0164592A1 EP 85105870 A EP85105870 A EP 85105870A EP 85105870 A EP85105870 A EP 85105870A EP 0164592 A1 EP0164592 A1 EP 0164592A1
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Prior art keywords
hydrogen
component
agent
composition according
weight
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German (de)
French (fr)
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EP0164592B1 (en
EP0164592B2 (en
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Heinrich Dr. Rellermeyer
Walter Meichsner
Werner Dr. Gmöhling
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Skw Stahl-Technik thyssen Stahl AG GmbH
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SKW Trostberg AG
Thyssen Stahl AG
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    • 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 of pig iron outside the blast furnace is an essential necessity due to the increasing sulfur content in the ores and black matter. Numerous means and processes have already been known for this, with which sufficient degrees of desulfurization can be achieved. Mixtures based on calcium carbide with diamide lime (DE-PS 17 58 250) and with additives which split off hydrogen (DE-PS 22 52 796) or water (DE-PS 22 52 795) are preferably used. Calcium-containing compounds in combination with hydrocarbons such as oil or paraffin (FR-PS 11 66 389 and US-PS 28 63 755) have already been proposed.
  • the purpose of the gas-releasing component is to distribute the finely ground particles of the basic desulfurization agent in the molten iron.
  • a commercially available product with contents of 70 to 85% CaC 2 is normally used as calcium carbide, but so-called eutectic carbide with contents of 65% CaC 2 and below can also be used.
  • Solid, liquid or gaseous hydrocarbons can be used as the hydrogen-releasing compounds.
  • solid hydrocarbons at room temperature are, for. B. polyethylene, polypropylene, polyvinyl chloride or polystyrene.
  • liquid hydrocarbons which may contain halogen
  • z. B. those with boiling points between 50 and 350 ° C
  • These liquid substances are preferably used in the form of a porous organic or inorganic material, which can contain up to a multiple of its own weight of hydrocarbon.
  • Preferred porous Materials for this purpose are those that can also split off hydrogen themselves or favorably influence the formation of slag, such as. B. polyurethane foam, peat or expanded minerals. If gaseous hydrocarbons are used, some or all of them can serve to blow the solid desulfurization mixture into the molten iron. Those hydrocarbons or mixtures thereof which contain little or no oxygen are preferred.
  • component A can also have 1 to 10% by weight of other constituents which have a favorable effect on the properties of the slag, such as, for example, B. fluorspar, alumina, cryolite or colemanite.
  • additives which release carbon dioxide such as, in particular, calcium carbonate, dolomite or diamide lime, individually or as a mixture, can preferably also be mixed in with component A.
  • carbon dioxide such as, in particular, calcium carbonate, dolomite or diamide lime, individually or as a mixture
  • component A additives which release carbon dioxide
  • additives which release carbon dioxide can preferably also be mixed in with component A.
  • their amount must be so limited that the volume of carbon dioxide developed therefrom and any other Co 2 -producting substances present is less than the volume of hydrogen developed from the compounds which release hydrogen.
  • These substances that release carbon dioxide can be ground together with the calcium carbide. If the specified quantity conditions are adhered to, they cause practically no oxidation of the magnesium or calcium carbide in the molten iron, but they increase the beneficial effect of the split off hydrogen through the CO 2 formed (which is also formed in certain quantities by the hydrocarbon).
  • component A may be expedient to additionally mix component A with brown or gas coal, anthracite or hard coal, which also have a gas-releasing effect.
  • component A can also be added in small amounts (about 0.01 to 0.5% by weight) with commercially available flow improvers such as graphite, long-chain organic amines, alcohols, esters or silicones.
  • the constituents of component A are ground and mixed intensively, the mixing process advantageously being carried out in a mill, which is preferably a tube mill, under an inert gas blanket.
  • the constituents are preferably comminuted to such an extent that 90% of the mixture has a grain size ⁇ 90 ⁇ m and about 50% has a grain size ⁇ 50 ⁇ m. Certain deviations from this are irrelevant to the desulfurization effect.
  • the magnesia can be added to the component in powder form in the mill or afterwards until component A contains a ratio of 70 to 99% by weight calcium carbide and 1 to 30% by weight essentially hydrogen-donating compounds.
  • M an can mix components A and B (Mg) before blowing into the iron melt, so that they are conveyed pneumatically into the melt as a mixture.
  • component A it has often proven to be expedient to store component A separately from the magnesium after its production and to combine it with the magnesium only in the delivery line or in the lance and to introduce it together into the melt.
  • the process according to the invention is characterized in that a mixture of calcium carbide and a hydrogen-releasing compound as component A is blown into the pig iron together with component B, the magnesium.
  • components A and B in a ratio of 40 to 95 to 5 to 60% by weight.
  • carbon dioxide-releasing substance such as alkaline earth metal carbonate, dolomite or diamide lime and hydrogen-releasing substance such as hydrocarbon
  • fluorspar and small amounts up to 0.5% by weight
  • the process is advantageously carried out in such a way that a blowing rate of 10 to 100 kg, preferably 15 to 80 kg, per minute of desulfurizing agent, consisting of component A and magnesium, is blown into the iron melt.
  • a blowing rate of 10 to 100 kg, preferably 15 to 80 kg, per minute of desulfurizing agent, consisting of component A and magnesium is blown into the iron melt.
  • the desulfurizing agent is preferably blown pneumatically into the molten iron as deeply as possible using a submersible lance.
  • carrier gases come inert gases such as argon or nitrogen alone or as a mixture, or reactive gases that split off hydrogen and / or contain CO 2 such as, for. B. propane or natural gas alone or as a mixture in question.
  • the desulfurization agent according to the invention is suitable in connection with the blowing process described just as well for hot metal desulfurization in the transfer pan as in the transport pan (torpedo pan).
  • the particularly low requirement for injection gas has a particularly advantageous effect; the composition of the agent guarantees sufficient distribution so that a high degree of utilization of the desulfurizing agent is achieved.
  • the desulfurization agent according to the invention has considerable advantages over the known agents in connection with the method according to the invention. According to the invention, a significant increase in the degree of desulfurization is achieved or a noticeably reduced amount of desulfurizing agent is required to achieve the same desulfurization effect.
  • the compounds which desulfurize the iron melt that is to say the calcium carbide and the alkaline earth metal, are completely available for the desulfurization reaction in combination with the compounds which essentially release hydrogen, since they are not consumed by oxidation processes.
  • Table 1 below describes various desulfurizing agents, their use and the results achieved with them. The results are averages from at least 3 desulfurization treatments each.
  • Examples 1 to 4 are comparative examples which were carried out using known desulfurization agents based on calcium carbide and diamide lime or calcium hydroxide and carbon.

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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)
  • Manufacture And Refinement Of Metals (AREA)
  • Catalysts (AREA)
  • Carbon And Carbon Compounds (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)
  • Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
  • Compounds Of Iron (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)

Abstract

A method and composition for desulfurization of hot metal is disclosed. To the hot metal there is added a composition comprising calcium carbide, a hydrogen releasing compound and magnesium.

Description

Die Entschwefelung des Roheisens außerhalb des Hochofens ist infolge der zunehmenden Schwefelgehalte in den Erzen und Schwarzstoffen eine unabdingbare Notwendigkeit. Hierfür wurden bereits zahlreiche Mittel und Verfahren bekannt, mit denen ausreichende Entschwefelungsgrade erreicht werden. Bevorzugt werden Gemische auf Basis von Calciumcarbid mit Diamidkalk (DE-PS 17 58 250) sowie mit Wasserstoff (DE-PS 22 52 796) oder Wasser (DE-PS 22 52 795) abspaltenden Zusätzen verwendet. Auch Calcium enthaltende Verbindungen in Kombination mit Kohlenwasserstoffen, wie öl oder Paraffin (FR-PS 11 66 389 und US-PS 28 63 755), wurden bereits vorgeschlagen. Aus der DE-AS 25 31 047 ist ein Verfahren zum Entschwefeln von Roheisen bekannt, das als Entschwefelungsmittel eine Mischung aus Calciumcarbid, Kalkstickstoff oder Kalk mit einem Anteil von 0,5 bis 3,5 % Aluminium- oder Magnesiumpulver bezogen auf die Calciumverbindungen, verwendet.Desulphurization of pig iron outside the blast furnace is an essential necessity due to the increasing sulfur content in the ores and black matter. Numerous means and processes have already been known for this, with which sufficient degrees of desulfurization can be achieved. Mixtures based on calcium carbide with diamide lime (DE-PS 17 58 250) and with additives which split off hydrogen (DE-PS 22 52 796) or water (DE-PS 22 52 795) are preferably used. Calcium-containing compounds in combination with hydrocarbons such as oil or paraffin (FR-PS 11 66 389 and US-PS 28 63 755) have already been proposed. From DE-AS 25 31 047 a method for desulfurizing pig iron is known which uses a mixture of calcium carbide, lime nitrogen or lime with a proportion of 0.5 to 3.5% aluminum or magnesium powder based on the calcium compounds as the desulfurizing agent .

Die vorgenannten Entschwefelungsmittel, insbesondere solche auf Basis von Calciumcarbid in Kombination mit Diamidkalk oder Calciumcarbonat als gasabspaltende Komponente, haben in der Technik Eingang gefunden und werden in großen Mengen hergestellt und in der Eisen-und Stahlindustrie verwendet.The abovementioned desulfurization agents, in particular those based on calcium carbide in combination with diamide lime or calcium carbonate as a gas-releasing component, have found their way into technology and are produced in large quantities and used in the iron and steel industry.

Zweck der gasabspaltenden Komponente ist es, die feingemahlenen Teilchen des Basis-Entschwefelungsmittels in der Eisenschmelze zu verteilen.The purpose of the gas-releasing component is to distribute the finely ground particles of the basic desulfurization agent in the molten iron.

Es wurde jedoch gefunden, daß die Abspaltung von Kohlendioxidaus carbonathaltigen Bestandteilen unter den Bedingungen der Roheisenschmelze Oxidationsvorgänge infolge Dissoziation in Kohlenmonoxid und Sauerstoff bewirkt. Hierdurch geht ein beträchtlicher Teil der eigentlichen entschwefelnd wirkenden Verbindungen für die Entschwefelungsreaktion verloren, so daß die Ausbeute an eingebrachtem Entschwefelungsmittel unbefriedigend bleibt.However, it has been found that the elimination of carbon dioxide from carbonate-containing constituents, under the conditions of the pig iron melt, causes oxidation processes due to dissociation in carbon monoxide and oxygen. As a result, a considerable part of the actual desulfurizing compounds are lost for the desulfurization reaction, so that the yield of the desulfurizing agent introduced remains unsatisfactory.

In der US-Patentschrift 39 98 625 wird ein Entschwefelungsmittel, bestehend aus einer Kombination von Kalk und weiteren Bestandteilen mit Magnesium beschrieben, sowie in der US-Patentschrift 42 66 969 der Einsatz von Kalk zusammen mit kohlenstoffhaltigem Material und einem nichtoxidierenden Fördergas empfohlen. In beiden Fällen bereiten die großen anfallenden Schlackenmengen infolge des nur schwach ausgeprägten entschwefelnden Effektes des Kalks beträchtliche Probleme.In US Patent 39 98 625 a desulfurization agent described consisting of a combination of lime and other constituents of magnesium, as well as in US - recommended Patent 42 66 969 the use of lime together with carbonaceous material and a non-oxidizing conveying gas. In both cases, the large amounts of slag produced cause considerable problems due to the weakly desulfurizing effect of the lime.

Es bestand daher die Aufgabe, ein Mittel und Verfahren zur Entschwefelung von Roheisen zu schaffen, womit man die bisherigen Nachteile vermeidet und entsprechend günstige Verbrauchswerte erreicht.It was therefore the task of creating a means and process for the desulfurization of pig iron, thereby avoiding the previous disadvantages and achieving correspondingly favorable consumption values.

Gegenstand der Erfindung ist daher das in den Patentansprüchen definierte feinkörnige Entschwefelungsmittel für Eisenschmelzen, bestehend im wesentlichen aus einer Kombination von

  • A) Calciumcarbid und wenigstens einer Substanz, die unter den Bedingungen der Roheisenschmelze im wesentlichen Wasserstoff abspaltet und
  • B) magnesium.
Is therefore the object of the invention in the patent claims defined fine-grained desulphurisation agent for E isenschmelzen consisting essentially of a combination of
  • A) calcium carbide and at least one substance which essentially splits off hydrogen under the conditions of the pig iron melting and
  • B) magnesium.

Ein Gemisch, bestehend aus Calciumcarbid und weiteren bei der Temperatur der Eisenschmelze Wasserstoff abspaltenden Verbindungen hat folgende Vorzüge:

  • a) Calciumcarbid wirkt in Eisenschmelzen entschwefelnd;
  • b) die bei der Temperatur der Eisenschmelze Wasserstoff abspaltende Substanz verhindert die Oxidation des Calciumcarbid und des Magnesium;
  • c) der freigesetzte Wasserstoff zusammen mit dem Einblasgas mischt die Reaktionsteilnehmer intensiv mit der zu entschwefelnden Roheisenschmelze und fördert die Bewegung der Eisenschmelze, wodurch der Kontakt des Entschwefelungsmittels mit der Eisenschmelze verbessert wird.
A mixture consisting of calcium carbide and other compounds that release hydrogen at the temperature of the molten iron has the following advantages:
  • a) Calcium carbide has a desulfurizing effect in molten iron;
  • b) the substance which releases hydrogen at the temperature of the molten iron prevents the oxidation of calcium carbide and magnesium;
  • c) the released hydrogen together with the injection gas mixes the reactants intensively with the pig iron to be desulfurized and promotes the movement of the iron melt, whereby the contact of the desulfurization agent with the iron melt is improved.

Als Calciumcarbid wird normalerweise ein handelsübliches Produkt mit Gehalten von 70 bis 85 % CaC2 verwendet, aber auch sogenanntes eutektisches Carbid mit Gehalten von 65 % CaC2 und darunter kann verwendet werden.A commercially available product with contents of 70 to 85% CaC 2 is normally used as calcium carbide, but so-called eutectic carbide with contents of 65% CaC 2 and below can also be used.

Als Wasserstoff abspaltende Verbindungen können feste, flüssige oder gasförmige Kohlenwasserstoffe verwendet werden. Als bei Raumtemperatur feste Kohlenwasserstoffe eignen sich z. B. Polyethylen, Polypropylen, Polyvinylchlorid oder Polystyrol.Solid, liquid or gaseous hydrocarbons can be used as the hydrogen-releasing compounds. As solid hydrocarbons at room temperature are, for. B. polyethylene, polypropylene, polyvinyl chloride or polystyrene.

Als flüssige Kohlenwasserstoffe, die gegebenenfalls Halogen enthalten, können z. B. solche mit Siedepunkten zwischen 50 und 350°C verwendet werden. Diese flüssigen Substanzen werden vorzugsweise in porösem organischen oder anorganischen Material aufgesaugter Form eingesetzt, welches bis zu einem mehrfachen seines eigenen Gewichts an Kohlenwasserstoff enthalten kann. Bevorzugte poröse Materialien für diesen Zweck sind solche, die selbst auch Wasserstoff abspalten können oder die Schlackenbildung günstig beeinflussen, wie z. B. Polyurethanschaum, Torf oder expandierte Mineralien. Werden gasförmige Kohlenwasserstoffe verwendet, so können diese zum Teil oder vollständig dazu dienen, das feste Entschwefelungsgemisch in die Eisenschmelze einzublasen. Bevorzugt werden solche Kohlenwasserstoffe bzw. deren Gemische, die keinen oder nur wenig Sauerstoff enthalten.As liquid hydrocarbons, which may contain halogen, z. B. those with boiling points between 50 and 350 ° C can be used. These liquid substances are preferably used in the form of a porous organic or inorganic material, which can contain up to a multiple of its own weight of hydrocarbon. Preferred porous Materials for this purpose are those that can also split off hydrogen themselves or favorably influence the formation of slag, such as. B. polyurethane foam, peat or expanded minerals. If gaseous hydrocarbons are used, some or all of them can serve to blow the solid desulfurization mixture into the molten iron. Those hydrocarbons or mixtures thereof which contain little or no oxygen are preferred.

Schließlich kann die Komponente A noch 1 bis 10 Gew.-% andere, die Eigenschaften der Schlacke günstig beeinflussende Bestandteile aufweisen, wie z. B. Flußspat, Tonerde, Kryolith oder Colemanit.Finally, component A can also have 1 to 10% by weight of other constituents which have a favorable effect on the properties of the slag, such as, for example, B. fluorspar, alumina, cryolite or colemanite.

Bei der Tempereratur der Eisenschmelze Kohlendioxid abspaltende Zusätze wie insbesondere Calciumcarbonat, Dolomit oder Diamidkalk einzeln oder als Gemisch, können der Komponente A vorzugsweise ebenfalls zugemischt sein. Ihre Menge muß jedoch so begrenzt sein, daß das daraus und eventuell vorhandenen weiteren Co2 liefernden Substanzen entwickelte Kohlendioxidvolumen geringer ist, als das aus den Wasserstoff abspaltenden Verbindungen entwickelte Wasserstoffvolumen. Diese Kohlendioxid abspaltenden Substanzen können zusammen mit dem Calciumcarbid vermahlen werden. Bei Einhaltung der oben angegebenen Mengenbedingung verursachen sie praktisch keine oxidation des Magnesium oder des Calciumcarbid in der Eisenschmelze, verstärken jedoch durch das gebildete C02 (welches in gewissen Mengen auch durch den Kohlenwasserstoff gebildet wird) die vorteilhafte Wirkung des abgespaltenen Wasserstoffs.At the temperature of the molten iron, additives which release carbon dioxide, such as, in particular, calcium carbonate, dolomite or diamide lime, individually or as a mixture, can preferably also be mixed in with component A. However, their amount must be so limited that the volume of carbon dioxide developed therefrom and any other Co 2 -producting substances present is less than the volume of hydrogen developed from the compounds which release hydrogen. These substances that release carbon dioxide can be ground together with the calcium carbide. If the specified quantity conditions are adhered to, they cause practically no oxidation of the magnesium or calcium carbide in the molten iron, but they increase the beneficial effect of the split off hydrogen through the CO 2 formed (which is also formed in certain quantities by the hydrocarbon).

Es kann zweckmäßig sein, der Komponente A noch zusätzlich Braun- oder Gaskohle, Anthrazit oder Steinkohle, die ebenfalls gasabspaltend wirken, zuzumischen.It may be expedient to additionally mix component A with brown or gas coal, anthracite or hard coal, which also have a gas-releasing effect.

Sollte es sich als erforderlich erweisen, können der Komponente A in geringen Mengen (etwa 0,01 bis 0,5 Gew.-%) auch noch handelsübliche Fließverbesserer wie Graphit, langkettige organische Amine, Alkohole, Ester oder Silikone zugesetzt werden.If it proves to be necessary, component A can also be added in small amounts (about 0.01 to 0.5% by weight) with commercially available flow improvers such as graphite, long-chain organic amines, alcohols, esters or silicones.

Zur Herstellung des erfindungsgemäßen Mittels werden die Bestandteile der Komponente A intensiv gemahlen und gemischt, wobei der Mischvorgang zweckmäßigerweise in einer Mühle, die vorzugsweise eine Rohrmühle ist, unter Inertgasdeckung erfolgt. Vorzugsweise werden die Bestandteile so weit zerkleinert, daß 90 % des Gemisches eine Kornoröße < 90 µm und etwa 50 % eine Kömgröße <50µm aufweisen. Gewisse Abweichungen hiervon sind ohne Belang auf den Entschwefelungseffekt. Das Magnesiun kann der Komponente Apulverförmig in der Mühle oder danach zugegeben werden, bis die Komponente A ein Verhältnis von 70 bis 99 Gew.-% Calciumcarbid und 1 bis 30 Gew.-% im wesentlichen Wasserstoff abgebende Verbindungen enthält.To produce the agent according to the invention, the constituents of component A are ground and mixed intensively, the mixing process advantageously being carried out in a mill, which is preferably a tube mill, under an inert gas blanket. The constituents are preferably comminuted to such an extent that 90% of the mixture has a grain size <90 μm and about 50% has a grain size <50 μm. Certain deviations from this are irrelevant to the desulfurization effect. The magnesia can be added to the component in powder form in the mill or afterwards until component A contains a ratio of 70 to 99% by weight calcium carbide and 1 to 30% by weight essentially hydrogen-donating compounds.

Man kann die Komponenten A und B (Mg) vor dem Einblasen in die Eisenschmelze mischen, so daß sie als Gemisch pneumatisch in die Schmelze gefördert werden. Andererseits hat es sich häufig als zweckmäßig erwiesen, die Komponente A nach ihrer Herstellung getrennt vom Magnesium zu lagern und sie erst in der Förderleitung oder in der Lanze mit dem Magnesium zu vereinigen und gemeinsam in die Schmelze einzubringen. M an can mix components A and B (Mg) before blowing into the iron melt, so that they are conveyed pneumatically into the melt as a mixture. On the other hand, it has often proven to be expedient to store component A separately from the magnesium after its production and to combine it with the magnesium only in the delivery line or in the lance and to introduce it together into the melt.

Das erfindungsgemäße Verfahren ist dadurch gekennzeich-net, daß ein Gemisch aus Calciumcarbid und einer Wasserstoff abspaltenden Verbindung als Komponente A gemeinsam mit der Komponente B, dem Magnesium, in das Roheisen eingeblasen wird.The process according to the invention is characterized in that a mixture of calcium carbide and a hydrogen-releasing compound as component A is blown into the pig iron together with component B, the magnesium.

Im allgemeinen ist es zweckmäßig, die Komponenten A und B im Verhältnis 40 bis 95 zu 5 bis 60 Gew.-% zu verwenden. Bevorzugt werden 50 bis 85 Gew.-% der Komponente A und 15 bis 50 Gew.-% gepulvertes Magnesium gleichzeitig in die Eisenschmelze eingeblasen. Besonders bevorzugt werden 65 bis 85 Gew.-% der Komponente A, die gegebenenfalls gleiche Mengen an Kohlendioxid abspaltender Substanz wie Erdalkalimetallcarbonat, Dolomit oder Diamidkalk und Wasserstoff abspaltender Substanz wie Kohlenwasserstoff enthält, sowie gegebenenfalls bis zu 5 Gew.-% Flußspat und geringe Mengen (bis zu 0,5 Gew.-%) eines Fließverbesserers, gemeinsam mit 15 bis 35 Gew.-% pulverisierten Magnesiums gleichzeitig in die Roheisenschmelze einzublasen.In general, it is expedient to use components A and B in a ratio of 40 to 95 to 5 to 60% by weight. Preferably 50 to 85% by weight of component A and 15 to 50% by weight of powdered magnesium are blown into the iron melt at the same time. Particular preference is given to 65 to 85% by weight of component A, which optionally contains the same amounts of carbon dioxide-releasing substance such as alkaline earth metal carbonate, dolomite or diamide lime and hydrogen-releasing substance such as hydrocarbon, and optionally up to 5% by weight of fluorspar and small amounts ( up to 0.5% by weight) of a flow improver, together with 15 to 35% by weight of powdered magnesium, to be blown into the pig iron melt at the same time.

Vorteilhaft wird das Verfahren so durchgeführt, daß man eine Einblasgeschwindigkeit von 10 bis 100 kg, vorzugsweise 15 bis 80 kg pro Minute an Entschwefelungsmittel, bestehend aus der Komponente A und Magnesium, in die Eisenschmelze einbläst. Bei Verwendung von 3 bis 30 Litern Trägergas pro kg Entschwefelungsgemisch wird hierbei ein optimaler Entschwefelungseffekt erreicht.The process is advantageously carried out in such a way that a blowing rate of 10 to 100 kg, preferably 15 to 80 kg, per minute of desulfurizing agent, consisting of component A and magnesium, is blown into the iron melt. When using 3 to 30 liters of carrier gas per kg of desulfurization mixture, an optimal desulfurization effect is achieved.

Das Entschwefelungsmittel wird vorzugsweise pneumatisch mit einer Tauchlanze so tief wie möglich in die Eisenschmelze eingeblasen. Als Trägergase kommen Inertgase wie Argon oder Stickstoff allein oder als Gemisch, oder reaktive Gase, die Wasserstoff abspalten oder/und CO2 enthalten wie z. B. Propan oder Erdgas allein oder als-Gemisch in Frage. Das erfindungsgemäße Entschwefelungsmittel eignet sich im Zusammenhang mit dem beschriebenen Einblasverfahren ebenso gut zur Roheisenentschwefelung in der Umfüllpfanne wie in der Transportpfanne (Torpedopfanne). Insbesondere in der Umfüllpfanne macht sich der besonders geringe Bedarf an Einblasgas besonders vorteilhaft bemerkbar; die Zusammensetzung des Mittels garantiert eine ausreichende Verteilung, so daß ein hoher Ausnutzungsgrad des Entschwefelungsmittels erreicht wird.The desulfurizing agent is preferably blown pneumatically into the molten iron as deeply as possible using a submersible lance. As carrier gases come inert gases such as argon or nitrogen alone or as a mixture, or reactive gases that split off hydrogen and / or contain CO 2 such as, for. B. propane or natural gas alone or as a mixture in question. The desulfurization agent according to the invention is suitable in connection with the blowing process described just as well for hot metal desulfurization in the transfer pan as in the transport pan (torpedo pan). In the transfer pan in particular, the particularly low requirement for injection gas has a particularly advantageous effect; the composition of the agent guarantees sufficient distribution so that a high degree of utilization of the desulfurizing agent is achieved.

Das erfindungsgemäße Entschwefelungsmittel weist in Verbindung mit dem erfindungsgemäßen Verfahren erhebliche Vorteile gegenüber den bekannten Mitteln auf. So wird erfindungsgemäß ein deutliche Steigerung des Entschwefelungsgrades erreicht bzw. eine merklich verringerte Menge an Entschwefelungsmittel zur Erzielung der gleichen Entschwefelungswirkung benötigt.The desulfurization agent according to the invention has considerable advantages over the known agents in connection with the method according to the invention. According to the invention, a significant increase in the degree of desulfurization is achieved or a noticeably reduced amount of desulfurizing agent is required to achieve the same desulfurization effect.

Die die Entschwefelung der Eisenschmelze bewirkenden Verbindungen, also das Calciumcarbid und das Erdalkalimetall, stehen in Kombination mit den im wesentlichen Wasserstoff abspaltenden Verbindungen vollständig für die Entschwefelungsreaktion zur Verfügung, da sie nicht durch Oxidationsvorgänge verbraucht werden.The compounds which desulfurize the iron melt, that is to say the calcium carbide and the alkaline earth metal, are completely available for the desulfurization reaction in combination with the compounds which essentially release hydrogen, since they are not consumed by oxidation processes.

Infolge der geringen benötigten Menge an Entschwefelungsmittel sind die Behandlungszeiten der Eisenschmelze kurz, so daß auch nur eine geringe Abkühlung der Schmelze erfolgt. Die entstehenden Schlackenmengen sind gering, so daß die Eisenverluste beim Abziehen der Schlacke unbedeutend sind.As a result of the small amount of desulfurization agent required, the treatment times for the iron melt are short, so that the melt is only slightly cooled. The amount of slag produced is small, so that the iron losses when removing the slag are insignificant.

Die nachfolgenden Beispiele sollen die Erfindung näher erläutern, ohne sie hierauf zu beschränken.The following examples are intended to explain the invention in more detail without restricting it thereto.

B e i s p i e l e 1 bis 8Example 1 to 8

In der nachstehenden Tabelle 1 sind verschiedene Entschwefelungsmittel, ihre Anwendung und die damit erzielten Ergebnisse beschrieben. Die Ergebnisse sind Mittelwerte aus mindestens jeweils 3 Entschwefelungsbehandlungen.Table 1 below describes various desulfurizing agents, their use and the results achieved with them. The results are averages from at least 3 desulfurization treatments each.

Die Beispiele 1 bis 4 sind Vergleichsbeispiele, die mit bekannten Entschwefelungsmitteln auf Basis von Calciumcarbid und Diamidkalk bzw. Calciumhydroxid und Kohlenstoff durchgeführt wurden.Examples 1 to 4 are comparative examples which were carried out using known desulfurization agents based on calcium carbide and diamide lime or calcium hydroxide and carbon.

Die Beispiele 5 bis 8 sind erfindungsgemäß.Examples 5 to 8 are according to the invention.

Alle Behandlungen wurden in 250 bis 400 t Roheisen fassenden Umfüllpfannen vorgenommen.All treatments were carried out in transfer pans holding 250 to 400 tons of pig iron.

Die in Tabelle 1 verwendeten Abkürzungen bedeuten:

Figure imgb0001
Gemisch die angegebenen Ziffern sind Gewichtsprozente
Figure imgb0002
Figure imgb0003
 The abbreviations used in Table 1 mean:
Figure imgb0001
 Mixture The numbers given are percentages by weight
Figure imgb0002
Figure imgb0003

Claims (19)

1. Feinkörniges Entschwefelungsmittel für Eisenschmelzen auf Basis von Calciumcarbid und weiteren Verbindungen, dadurch
gekennzeichnet , daß es im wesentlichen aus einer Kombination von A) Calciumcarbid und wenigstens einer unter den übrigen Bestandteilen des Mittels homogen verteilten, bei der Temperatur der Eisenschmelze Wasserstoff abspaltenden Substanz und B) Magnesium besteht. 1. Fine-grain desulfurization agent for molten iron based on calcium carbide and other compounds
characterized in that it consists essentially of a combination of A) calcium carbide and at least one substance which is homogeneously distributed among the other constituents of the agent and releases hydrogen at the temperature of the molten iron and B) Magnesium exists. 2. Mittel nach Anspruch 1, gekenn- zeichnet durch einen Gehalt an 40 bis 95 Gew.-% an Komponente A und 5 bis 60 Gew.-% Magnesium.2. Composition according to claim 1, characterized by a content of 40 to 95% by weight of component A and 5 to 60% by weight of magnesium. 3. Mittel nach Anspruch 1 oder 2, dadurch gekennzeichnet , daß etwa 90 % des festen Anteils der Komponente A eine Korngröße von <90 µm und etwa 50 % eine Korngröße <50 µm aufweisen.3. Composition according to claim 1 or 2, characterized in that about 90% of the solid portion of component A have a grain size of <90 microns and about 50% have a grain size <50 microns. 4. Mittel nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet , daß die Komponente A 70 bis 99 Gew.-% Calciumcarbid und 1 bis 30 Gew.-% Wasserstoff abspaltende Substanz enthält.4. Composition according to one of claims 1 to 3, characterized in that component A contains 70 to 99 wt .-% calcium carbide and 1 to 30 wt .-% hydrogen-releasing substance. 5. Mittel nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet , daß die Komponente A zusätzlich 1 bis 10 Gew.-% an die Konsistenz der Schlacke beeinflussenden Zusätzen wie Flußspat, Tonerde, Kryolith oder/und Colemanit enthält.5. Composition according to one of claims 1 to 4, characterized in that component A additionally contains 1 to 10% by weight of additives influencing the consistency of the slag, such as fluorspar, clay, cryolite and / or colemanite. 6. Mittel nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet , daß die Komponente A zusätzlich 0,01 bis 0,5 Gew.-% eines Fließverbesserers enthält.6. Composition according to one of claims 1 to 5, characterized in that component A additionally contains 0.01 to 0.5% by weight of a flow improver. 7. Mittel nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet , daß die Wasserstoff abspaltende Verbindung der Komponente A ein fester Kohlenwasserstoff oder ein fester halogenhaltiger Kohlenwasserstoff ist.7. Composition according to one of claims 1 to 6, characterized in that the hydrogen-releasing compound of component A is a solid hydrocarbon or a solid halogen-containing hydrocarbon. 8. Mittel nach Anspruch 7, dadurch gekennzeichnet , daß die Wasserstoff abspaltende Verbindung Polyethylen ist.8. Composition according to claim 7, characterized in that the hydrogen-releasing compound is polyethylene. 9. Mittel nach Anspruch 7, dadurch gekennzeichnet , daß die Wasserstoff abspaltende Verbindung Polypropylen ist.9. Composition according to claim 7, characterized in that the hydrogen-releasing compound is polypropylene. 10. Mittel nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet , daß die Wasserstoff abspaltende Substanz der Komponente A ein flüssiger Kohlenwasserstoff oder flüssiger halogenhaltiger Kohlenwasserstoff mit einem Siedepunkt zwischen 50 bis 350°C ist, der in einem porösen organischen oder anorganischen Material aufgesaugt vorliegt.10. Agent according to one of claims 1 to 6, characterized in that the hydrogen-releasing substance of component A is a liquid hydrocarbon or liquid halogen-containing hydrocarbon with a boiling point between 50 to 350 ° C, which is absorbed in a porous organic or inorganic material . 11. Mittel nach einem der Ansprüche 1 bis 10, dadurch gekennzeichnet , daß die Komponente A zusätzlich eine Kohlendioxid entwickelnde Substanz, insbesondere Calciumcarbonat, Dolomit oder/und Diamidkalk in solcher Menge enthält, daß das daraus entwickelte Kohlendioxidvolumen kleiner ist, als das bei der Temperatur der Eisenschmelze entbundene Wasserstoffvolumen aus der Wasserstoff abspaltenden Substanz.11. Agent according to one of claims 1 to 10, characterized in that component A additionally contains a carbon dioxide-developing substance, in particular calcium carbonate, dolomite and / or diamide lime in such an amount that the volume of carbon dioxide developed therefrom is less than that at temperature The hydrogen volume released from the iron melt from the hydrogen-releasing substance. 12. Mittel nach einem der Ansprüche 1 bis 11, dadurch gekennzeichnet , daß die Komponente A als Wasserstoff abspaltende Verbindung Braun- oder Gaskohle oder Anthrazit enthält.12. Composition according to one of claims 1 to 11, characterized in that component A contains lignite or gas coal or anthracite as a hydrogen-releasing compound. 13. Verfahren zur Entschwefelung von Roheisen mit einem Mittel nach einem der Ansprüche 1 bis 12, dadurch gekennzeichnet , daß das Mittel in fluidisierter Form mit einer Einblasgeschwindigkeit von 10 bis 100 kg pro Minute und 3 bis 20 1 Fördergas pro kg Entschwefelungsmittel unter die Oberfläche der Eisenschmelze eingeblasen wird.13. A process for the desulfurization of pig iron with an agent according to any one of claims 1 to 12, characterized in that the agent in fluidized form with an injection speed of 10 to 100 kg per minute and 3 to 20 l of conveying gas per kg of desulfurizing agent below the surface of the Iron melt is blown in. 14. Verfahren nach Anspruch 13, dadurch gekennzeichnet , daß das Mittel mit einer Förderrate von 15 bis 80 kg pro Minute in eine Umfüllpfanne eingeblasen wird.14. The method according to claim 13, characterized in that the agent is blown into a transfer pan at a delivery rate of 15 to 80 kg per minute. 15. Verfahren nach den Ansprüchen 13 oder 14, dadurch gekennzeichnet , daß das Fördergas ein Kohlenwasserstoff ist.15. The method according to claims 13 or 14, characterized in that the conveying gas is a hydrocarbon. 16. Verfahren nach den Ansprüchen 13 oder 14, dadurch gekennzeichnet , daß das Fördergas Stickstoff ist.16. The method according to claims 13 or 14, characterized in that the conveying gas is nitrogen. 17. Verfahren nach den Ansprüchen 13 oder 14, dadurch gekennzeichnet , daß das Fördergas Argon ist.17. The method according to claims 13 or 14, characterized in that the conveying gas is argon. 18. Verfahren nach einem der Ansprüche 13 bis 17, dadurch gekennzeichnet , daß man die Komponenten A und B in separaten Dispensern fluidisiert, in einer gemeinsamen Förderleitung vereinigt und über eine Lanze in die Eisenschmelze einbläst.18. The method according to any one of claims 13 to 17, characterized in that components A and B are fluidized in separate dispensers, combined in a common delivery line and blown into the molten iron via a lance. 19. Verfahren nach den Ansprüchen 13 bis 18, dadurch gekennzeichnet daß man 65 bis 85 Gew.-% der Komponente A, welche Wasserstoff und Kohlendioxid entwickelnde Verbindungen in solcher Menge enthält, daß das daraus entwickelte Wasserstoffvolumen größer ist als das daraus entwickelte Kohlendioxidvolumen, sowie gegebenenfalls bis zu 5 Gew.-% Flußspat und bis zu 0,5 Gew.-% eines Fließverbesserers gemeinsam mit 5 bis 35 Gew.-% pulverisiertem Magnesium in die Roheisenschmelze einbläst.19. The method according to claims 13 to 18, characterized in that 65 to 85 wt .-% of component A, which contains hydrogen and carbon dioxide-developing compounds in such an amount that the hydrogen volume developed therefrom is greater than the carbon dioxide volume developed therefrom, and optionally blowing up to 5% by weight of fluorspar and up to 0.5% by weight of a flow improver into the pig iron melt together with 5 to 35% by weight of powdered magnesium.
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EP0226994A1 (en) * 1985-12-17 1987-07-01 SKW Trostberg Aktiengesellschaft Agent for desulphuration of molten iron and process for its production
EP0387580A1 (en) * 1989-03-13 1990-09-19 Hoechst Aktiengesellschaft Agent and method for desulfurizing molten metals
EP0511121A1 (en) * 1991-04-02 1992-10-28 Pechiney Electrometallurgie Desulfurisation agent for pig iron, comprising calcium carbide and an organic binder
EP0514294A1 (en) * 1991-05-16 1992-11-19 Pechiney Electrometallurgie Agent for desulfphuration of cast iron consisting of magnesium coated with calcium carbide
FR2679256A1 (en) * 1991-07-18 1993-01-22 Pechiney Electrometallurgie Desulphuriser for liquid pig iron based on agglomerated calcium carbide
FR2688230A1 (en) * 1992-03-05 1993-09-10 Pechiney Electrometallurgie Desulphuriser for pig iron, based on ultrafine magnesium or calcium carbide powders which are agglomerated with a polymeric binder
WO1997021841A1 (en) * 1995-12-12 1997-06-19 Skw Trostberg Aktiengesellschaft Desulphurating agent for co-injection treatment of pig iron melts
RU2166548C2 (en) * 1996-04-04 2001-05-10 Пешинэ Электрометалюржи Desulfurizing mixture based on calcium carbide
EP2272991A1 (en) 2009-07-06 2011-01-12 SKW Stahl-Metallurgie GmbH Method and agent for treating raw iron desulphurisation slags
US9187792B2 (en) 2011-01-15 2015-11-17 Alamamet GmbH Agent for treating molten metals, method for the production and use thereof
US10190183B2 (en) 2011-10-20 2019-01-29 Almamet Gmbh Method for desulfurizing

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DE3544563C2 (en) * 1985-12-17 1998-07-16 Sueddeutsche Kalkstickstoff Means for desulfurizing molten iron
EP0226994A1 (en) * 1985-12-17 1987-07-01 SKW Trostberg Aktiengesellschaft Agent for desulphuration of molten iron and process for its production
DE3544563A1 (en) * 1985-12-17 1987-06-19 Sueddeutsche Kalkstickstoff Agent for desulphurising molten iron
EP0387580A1 (en) * 1989-03-13 1990-09-19 Hoechst Aktiengesellschaft Agent and method for desulfurizing molten metals
EP0511121A1 (en) * 1991-04-02 1992-10-28 Pechiney Electrometallurgie Desulfurisation agent for pig iron, comprising calcium carbide and an organic binder
FR2676457A1 (en) * 1991-05-16 1992-11-20 Pechiney Electrometallurgie DESULFURANT FOR CAST IRON CONSISTING OF MIXED MAGNESIUM AND CALCIUM CARBIDE.
EP0514294A1 (en) * 1991-05-16 1992-11-19 Pechiney Electrometallurgie Agent for desulfphuration of cast iron consisting of magnesium coated with calcium carbide
FR2679256A1 (en) * 1991-07-18 1993-01-22 Pechiney Electrometallurgie Desulphuriser for liquid pig iron based on agglomerated calcium carbide
FR2688230A1 (en) * 1992-03-05 1993-09-10 Pechiney Electrometallurgie Desulphuriser for pig iron, based on ultrafine magnesium or calcium carbide powders which are agglomerated with a polymeric binder
WO1997021841A1 (en) * 1995-12-12 1997-06-19 Skw Trostberg Aktiengesellschaft Desulphurating agent for co-injection treatment of pig iron melts
RU2166548C2 (en) * 1996-04-04 2001-05-10 Пешинэ Электрометалюржи Desulfurizing mixture based on calcium carbide
EP2272991A1 (en) 2009-07-06 2011-01-12 SKW Stahl-Metallurgie GmbH Method and agent for treating raw iron desulphurisation slags
EP2275580A1 (en) 2009-07-06 2011-01-19 SKW Stahl-Metallurgie GmbH Method and agent for treating raw iron desulphurisation slags
US9187792B2 (en) 2011-01-15 2015-11-17 Alamamet GmbH Agent for treating molten metals, method for the production and use thereof
US10190183B2 (en) 2011-10-20 2019-01-29 Almamet Gmbh Method for desulfurizing

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