EP0164592B2 - 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
EP0164592B2
EP0164592B2 EP85105870A EP85105870A EP0164592B2 EP 0164592 B2 EP0164592 B2 EP 0164592B2 EP 85105870 A EP85105870 A EP 85105870A EP 85105870 A EP85105870 A EP 85105870A EP 0164592 B2 EP0164592 B2 EP 0164592B2
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hydrogen
component
agent
splitting
agent according
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French (fr)
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EP0164592A1 (en
EP0164592B1 (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

  • the invention relates to means and methods for the desulfurization of pig iron melts.
  • Desulphurization of pig iron outside the blast furnace is an indispensable necessity due to the increasing sulfur content in the ores and black matter. Numerous means and processes have already been known for achieving sufficient levels of desulphurization. Mixtures based on calcium carbide with diamide lime (DE-PS 17 58 250) and with hydrogen (DE-PS 22 52 796) or water (DE-PS 22 52 795) additives 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 base desulfurization agent in the molten iron.
  • DE-OS 28 35 872 describes a process for the desulfurization of pig iron using a desulfurization mixture of calcium carbide, a gas-releasing component and fluorspar; A large number of water-releasing compounds, hydrogen-releasing compounds and carbon dioxide-releasing compounds are equally mentioned as gas-releasing components.
  • the desulfurization agent can also contain reducing metals and metal carbides, such as. As aluminum, magnesium, alloys, such as. As calcium silicon or metal carbides.
  • Another subject is a desulfurization process, in which the desulfurization agent according to the invention is used, according to claim 11.
  • a commercially available product with contents of 70 to 85% CaC Z is normally used as calcium carbide, but so-called eutectic carbide with contents of 65% CaC 2 and below can also be used.
  • Solid or liquid 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 can be used.
  • These liquid substances are preferably used in a form absorbed in 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 which themselves can also split off hydrogen or have a favorable influence on the formation of slags, such as, for example, B. polyurethane foam, peat or expanded minerals.
  • 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. 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
  • component A can be so limited that the volume of carbon dioxide developed therefrom and any other C0 2- delivering 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 increase the beneficial effect of the split off hydrogen by 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) also 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 magnesium can be added to component A in powder form in the mill or afterwards if component A is, for. B. contains a ratio of 70 to 99 wt .-% calcium carbide and 1 to 30 wt .-% essentially hydrogen-releasing compounds.
  • Components A and B can be mixed before being blown into the molten iron, so that they are conveyed pneumatically into the melt as a mixture.
  • component A can 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 are used 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
  • 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 desulfurization agent is preferably blown pneumatically into the molten iron as deeply as possible using a submersible lance.
  • Inert gases such as argon or nitrogen come alone or as a mixture, or reactive gases which release hydrogen and / or contain CO 2 , alone or as a mixture, as carrier gases 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 cause the desulfurization of the molten iron, that is to say the calcium carbide and the magnesium, in combination with the compounds which essentially release hydrogen, are completely available for the desulfurization reaction 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.
  • a-value Indicator for the effectiveness of desulfurization (quotient of the difference between the initial and final sulfur content of the pig iron melt and the amount of desulfurizing agent used per ton of pig iron).

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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)
  • Manufacture Of Macromolecular Shaped Articles (AREA)
  • Catalysts (AREA)
  • Carbon And Carbon Compounds (AREA)
  • Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
  • Compounds Of Iron (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 Erfindung betrifft Mittel und Verfahren zur Entschwefelung von Roheisenschmelzen.The invention relates to means and methods for the desulfurization of pig iron melts.

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 indispensable necessity due to the increasing sulfur content in the ores and black matter. Numerous means and processes have already been known for achieving sufficient levels of desulphurization. Mixtures based on calcium carbide with diamide lime (DE-PS 17 58 250) and with hydrogen (DE-PS 22 52 796) or water (DE-PS 22 52 795) additives 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.

Zweckdergasabspaltenden 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 base desulfurization agent in the molten iron.

Es wurde jedoch gefunden, daß die Abspaltung von Kohlendioxid aus 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 constituents containing carbonate, 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 die Entschwefelung von Roheisen durch Einblasen einer Mischung fluidisierter Teilchen aus einem nichtoxidierenden Feststoff, z. B. CaC2, und aus einem Magnesium enthaltenden reaktiven Material, z. B. Magnesium, mittels eines nichtoxidierenden Trägergases, z. B. reduzierendes Kohlenwasserstoffgas, beschrieben. In der US-Patentschrift 42 66 969 wird 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 beträchtliche Probleme.In US Pat. No. 3,998,625, the desulfurization of pig iron is carried out by blowing in a mixture of fluidized particles from a non-oxidizing solid, e.g. B. CaC 2 , and from a magnesium-containing reactive material, for. B. magnesium, by means of a non-oxidizing carrier gas, e.g. B. reducing hydrocarbon gas. In US Pat. No. 4,266,969, the use of lime together with carbon-containing material and a non-oxidizing gas is recommended. In both cases, the large amounts of slag produced cause considerable problems due to the weakly desulfurizing effect.

Die DE-OS 28 35 872 beschreibt ein Verfahren zum Entschwefeln von Roheisen unter Verwendung eines Entschwefelungsgemisches aus Calciumcarbid, einer gasabspaltenden Komponente und Flußspat; als gasabspaltende Komponenten werden eine Vielzahl von wasserabspaltenden Verbindungen, Wasserstoff-abspaltenden Verbindungen und Kohlendioxid-abspaltenden Verbindungen gleichwertig nebeneinander genannt. Zusätzlich kann das Entschwefelungmittel auch noch reduzierend wirkende Metalle und Metallcarbide enthalten, wie z. B. Aluminium, Magnesium, Legierungen, wie z. B. Calciumsilizium oder Metallcarbide.DE-OS 28 35 872 describes a process for the desulfurization of pig iron using a desulfurization mixture of calcium carbide, a gas-releasing component and fluorspar; A large number of water-releasing compounds, hydrogen-releasing compounds and carbon dioxide-releasing compounds are equally mentioned as gas-releasing components. In addition, the desulfurization agent can also contain reducing metals and metal carbides, such as. As aluminum, magnesium, alloys, such as. As calcium silicon or metal carbides.

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. Diese Aufgabe wird mit der vorliegenden Erfindung gelöst.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. This object is achieved with the present invention.

Gegenstand der Erfindung ist das im Patentanspruch 1 definierte feinkörnige Entschwefelungsmittel für Eisenschmelzen, das aus einer Kombination von

  • A) Calciumcarbid und wenigstens einer festen oder flüssigen Substanz, die unter den Bedingungen der Roheisenschmelze im wesentlichen Wasserstoff abspaltet und
  • B) Magnesium
besteht. Die Komponente A kann gegebenenfalls noch eine bei der Temperatur der Eisenschmelze Kohlendioxid abspaltende Substanz und gegebenenfalls bis zu 0,5 Gew.% eines Fließverbesserers enthalten.The invention relates to the fine-grained desulfurization agent for iron melts defined in claim 1, which consists of a combination of
  • A) calcium carbide and at least one solid or liquid substance which, under the conditions of the pig iron melt, essentially releases hydrogen and
  • B) Magnesium
consists. Component A may optionally also contain a substance which releases carbon dioxide at the temperature of the molten iron and optionally up to 0.5% by weight of a flow improver.

Weiterer Gegenstand ist ein Entschwefelungsverfahren, bei dem das erfindungsgemäße Entschwefelungsmittel eingesetzt wird, nach Anspruch 11.Another subject is a desulfurization process, in which the desulfurization agent according to the invention is used, according to claim 11.

Zweckmäßige Ausgestaltungen des Mittels nach Anspruch 1 und des Verfahrens nach Anspruch 11 sind Gegenstand der Ansprüche 2 bis 10 und 12 bis 16.Appropriate embodiments of the agent according to claim 1 and the method according to claim 11 are the subject of claims 2 to 10 and 12 to 16.

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

  • a) Calciumcarbid wirkt in Eisenschmelzen entschwefeInd ;
  • 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% CaCZVerwendet, 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 Z 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 oderflüssige Kohlenwasserstoffe verwendet werden. Als bei Raumtemperatur feste Kohlenwasserstoffe eignen sich z. B. Polyethylen, Polypropylen, Polyvinylchlorid oder Polystyrol.Solid or liquid 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 in porösem organischen oderanorganischen 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. 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 a form absorbed in 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 which themselves can also split off hydrogen or have a favorable influence on the formation of slags, such as, for example, B. polyurethane foam, peat or expanded minerals. 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. B. fluorspar, alumina, cryolite or colemanite.

Bei der Temperatur 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 C02 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 C0 2- delivering 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 increase the beneficial effect of the split off hydrogen by 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) also 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 Komgröße < 90 µm und etwa 50 % eine Korngröße < 50 µm aufweisen. Gewisse Abweichungen hiervon sind ohne Belang auf den Entschwefelungseffekt. Das Magnesium kann der Komponente A pulverförmig in der Mühle oder danach zugegeben werden, wenn die Komponente A z. B. 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 magnesium can be added to component A in powder form in the mill or afterwards if component A is, for. B. contains a ratio of 70 to 99 wt .-% calcium carbide and 1 to 30 wt .-% essentially hydrogen-releasing 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.Components A and B (Mg) can be mixed before being blown into the molten iron, 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 gekennzeichnet, 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.

Die Komponenten A und B werden Verhältnis 40 bis 95 zu 5 bis 60 Gew.-% verwendet. 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 eingeblasen.Components A and B are used 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, are simultaneously blown into the pig iron melt.

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 (Fördergas) 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 (conveying 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 C02 enthalten, allein oder als Gemisch in Frage.The desulfurization agent is preferably blown pneumatically into the molten iron as deeply as possible using a submersible lance. Inert gases such as argon or nitrogen come alone or as a mixture, or reactive gases which release hydrogen and / or contain CO 2 , alone or as a mixture, as carrier gases Question.

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 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 Magnesium 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 cause the desulfurization of the molten iron, that is to say the calcium carbide and the magnesium, in combination with the compounds which essentially release hydrogen, are completely available for the desulfurization reaction 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.

Beispiele 1 bis 7Examples 1 to 7

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 7 sind erfindungsgemäß.Examples 5 to 7 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 :

  • SA Ausgangs-Schwefel-Gehalt der Roheisenschmelze
  • SE Endschwefelgehalt der RE-Schmelze nach der Behandlung
  • kg/t die angewendete Menge Entschwefelungsmittel pro t Roheisen
  • kg/Min. Förderrate des Entschwefelungsmittels pro Minute
  • NI/Min. Fördergasmenge in Normal-Liter pro Minute
  • Nilkg Fördergasmenge pro kg Entschwefelungsgemisch
The abbreviations used in Table 1 mean:
  • S A Initial sulfur content of the pig iron melt
  • S E final sulfur content of the RE melt after the treatment
  • kg / t the amount of desulphurising agent used per t of pig iron
  • kg / min. Rate of desulfurization per minute
  • NI / min. Flow rate in normal liters per minute
  • Nilkg conveying gas quantity per kg desulfurization mixture

a-Wert Kennzifferfür die Wirksamkeit der Entschwefelung (Quotient aus der Differenz zwischen Ausgangs-und Endschwefelgehalt der Roheisenschmelze und aufgewandter Menge Entschwefelungsmittel pro t Roheisen).a-value Indicator for the effectiveness of desulfurization (quotient of the difference between the initial and final sulfur content of the pig iron melt and the amount of desulfurizing agent used per ton of pig iron).

Gemisch die angegebenen Ziffern sind Gewichtsprozente

  • CaC2 = techn. Calciumcarbid
  • Ca(OH)2 = Calciumhydroxid (trocken)
  • Mg = Magnesium
  • PE = Polyethylen
  • PP = Polypropylen
  • CaF2 = Flußspat.
Figure imgb0001
 Mixture The numbers given are percentages by weight
  • CaC 2 = techn. Calcium carbide
  • Ca (OH) 2 = calcium hydroxide (dry)
  • Mg = magnesium
  • PE = polyethylene
  • PP = polypropylene
  • CaF 2 = fluorspar.
Figure imgb0001

Claims (16)

1. Fine-grained desulphurisation agent for iron melts based on calcium carbide and further compounds, consisting of a combination of
A) 40 to 95 wt.% calcium carbide and at least one solid or liquid substance splitting off hydrogen at the temperature of the iron melt, homogeneously distributed with the other components of the agent and possibly a substance splitting off carbon dioxide at the temperature of the iron melt, whereby the component A can possibly contain up to 0.5 wt.% of a flow improver, whereby about 90% of the solid part of component A has a grain size of < 90 µm and about 50% a grain size of < 50 pm, as well as
B) 5 to 60 wt.% magnesium.
2. Agent according to claim 1, characterised in that the component A contains 70 to 99 wt.% of calcium carbide and 1 to 30 wt.% of substance splitting off hydrogen.
3. Agent according to claim 1 or 2, characterised in that the component A additionally contains 1 to 10 wt.% of additives influencing the consistency of the slag, such as fluorite, pure clay, cryolite and/or colemanite.
4. Agent according to one of claims 1 to 3, characterised in that the component A additionally contains 0.01 to 0.5 wt.% of a flow improver.
5. Agent according to one of claims 1 to 4, characterised in that the compound of component A splitting off hydrogen is a solid hydrocarbon or a solid, halogen-containing hydrocarbon.
6. Agent according to claim 5, characterised in that the compound splitting off hydrogen is polyethylene.
7. Agent according to claim 5, characterised in that the compound splitting off hydrogen is polypropylene.
8. Agent according to one of claims 1 to 4, characterised in that the substance of the component A splitting off hydrogen is a liquid hydrocarbon or a liquid, halogen-containing hydrocarbon with a boiling point between 50 and 350°C. which is present absorbed in a porous organic or inorganic material.
9. Agent according to'one of claims 1 to 8, characterised in that the component A additionally contains a substance evolving carbon dioxide, especially calcium carbonate, dolomite and/or diamide lime, in such an amount that the volume of carbon dioxide evolved therefrom is smaller than the volume of hydrogen liberated at the temperature of the iron melt from the substance splitting off hydrogen.
10. Agent according to one of claims 1 to 9, characterised in that the component A additionally contains, as compound splitting off gas, lignite, stone or gas coal.
11. Process for the desulphurisation of pig iron with an agent according to one of claims 1 to 10, characterised in that the agent is blown in in fluidised form under the surface of the iron melt with a blowing-in rate of 10 to 100 kg. per minute and 3 to 30 carrier gas per kg. of desulphurisation agent.
12. Process according to claim 11, characterised in that the agent is blown into a transfer ladle with a conveying rate of 15 to 80 kg. per minute.
13. Process according to claim 11 or 12, characterised in that the carrier gas is nitrogen.
14. Process according to claim 11 or 12, characterised in that the carrier gas is argon.
15. Process according to one of claims 11 to 14, characterised in that one fluidises the components A and B in separate dispensers, combines in a common conveyor pipe and blows into the iron melt via a lance.
16. Process according to claims 11 to 15, characterised in that one blows into the pig iron melt 65 to 85 wt.% of component A, which contains compounds evolving hydrogen and carbon dioxide, in such an amount that the hydrogen volume evolved therefrom is greater than the carbon dioxide volume evolved, as well as possibly up to 5 wt.% of fluorite and up to 0.5 wt.% of a flow improver, together with 15 to 35 wt% of pulverised magnesium.
EP85105870A 1984-05-16 1985-05-13 Fine-grained desulfurization agent forron melts, and process for the desulfurization of molten pig iron Expired - Lifetime EP0164592B2 (en)

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ZA853556B (en) 1985-12-24
FI78736C (en) 1989-09-11
CA1240842A (en) 1988-08-23
IN162816B (en) 1988-07-09
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AU568056B2 (en) 1987-12-10
FI78736B (en) 1989-05-31
EP0164592B1 (en) 1988-06-15
DE3563360D1 (en) 1988-07-21
NO165765B (en) 1990-12-27
US4592777A (en) 1986-06-03
NO165765C (en) 1991-04-10
NO851924L (en) 1985-11-18

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