EP0226994A1 - Agent for desulphuration of molten iron and process for its production - Google Patents
Agent for desulphuration of molten iron and process for its production Download PDFInfo
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- EP0226994A1 EP0226994A1 EP86117417A EP86117417A EP0226994A1 EP 0226994 A1 EP0226994 A1 EP 0226994A1 EP 86117417 A EP86117417 A EP 86117417A EP 86117417 A EP86117417 A EP 86117417A EP 0226994 A1 EP0226994 A1 EP 0226994A1
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- coal
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- molten iron
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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 agents, processes for producing the agent and application of the agent for the desulfurization of molten iron outside the blast furnace.
- iron smelting means pig iron and cast iron melting.
- a preferred agent is a mixture consisting of 20 to 90% by weight technical calcium carbide and calcium carbonate, preferably in precipitated form and 2 to 20% by weight carbon distributed therein, the finely divided calcium carbonate / carbon mixture being known under the name diamide lime ( DE-PS 17 58 250).
- US Pat. No. 3,998,625 describes a desulfurization agent consisting of a combination of lime and other constituents with magnesium
- US Pat. No. 4,266,969 recommends the use of lime with carbon-containing material and a non-oxidizing production gas.
- a disadvantage of the known agents is the large amounts of slag which lead to undesirable deposits and incrustations, particularly in the torpedo pans but also in the open pans, and moreover include considerable amounts of iron, which leads to considerable iron losses.
- Desulfurizing agent in the treatment of cast iron melts together with carbon e.g. B. in the form of pitch coke, blood coal, leather coal, but the coal types proposed for this purpose contain practically no volatile constituents (see the prior art indicated in DE-PS 17 58 250).
- Technical calcium carbide is understood to mean a commercial product which contains 65 to 85% by weight of CaC z and the rest of which consists predominantly of lime.
- the proportion of technical calcium carbide can vary within wide limits in the agent according to the invention. The contents of the remaining components fluctuate accordingly.
- a desulfurization agent is preferably used which contains 50 to 98% by weight calcium carbide and 50 to 2% by weight coal.
- the agent particularly preferably contains 80 to 96% by weight of calcium carbide and 20 to 4% by weight of coal.
- the desulfurization agent according to the invention can additionally contain magnesium. Mixtures with contents of 47.5 to 95.5% by weight of technical calcium carbide, 50 to 2% by weight of dried coal and 2 to 40% by weight of magnesium are preferred.
- a coal type is preferably selected as the carbon component, which as the dried product is pneumatically introduced into the molten iron, ie at a heating rate of 10 3 to 10 6 ° C / sec. releases about 90% by weight of the volatile constituents within less than 60 seconds, preferably less than 40 seconds.
- the higher the volatile content in the coal the higher the effectiveness of the desulfurization agent.
- Coals containing at least 25% by weight of volatile constituents are therefore particularly preferably used.
- Coals are preferably used which develop a gas volume of at least 150 NL / kg in the dried form immediately after entering the iron melt. Coals that meet these conditions are in particular lignite, flame coal, gas flame coal, gas coal and fat coal (see Table 1).
- two or more types of coal with high volatile constituents can also be used in the mixture.
- the moisture content of the dried coal is preferably less than 0.5% by weight in order to prevent acetylene formation by reaction with the calcium carbide.
- Such degrees of dryness are achieved in commercially available drying devices such as swirl flow driers, entrained flow driers or grinding driers and when drying in a vacuum in simple units, in which the material to be dried is merely circulated.
- the magnesium to be used should have a grain size of less than 1 mm.
- a magnesium is preferably used which has already been comminuted ⁇ 500 ⁇ m, particularly preferred is a magnesium which has a grain size ⁇ 350 ⁇ m.
- fluorspar a proportion of 1 to 10% by weight of fluorspar to the desulfurization mixture, e.g. B. to favorably influence the properties of the slag formed during the desulfurization treatment.
- 2 to 6% by weight of fluorspar is added to the mixture.
- ball mill dust waste from aluminum production
- the desulfurization agent according to the invention is produced in such a way that the dried coal is metered into the pre-broken or pre-ground calcium carbide and the mixture is ground in a mill to the desired degree of fineness. It can be useful to work under an inert gas blanket in order to remove any small amounts of acetylene from the mixing and grinding plant. However, the carbide and the coal can also be ground separately and subsequently mixed together.
- the components of the agent according to the invention are intensively ground and mixed, these preferably being comminuted to such an extent that at least 90% by weight of the mixture has a grain size ⁇ 200 ⁇ m, but particularly preferably 90% a grain size ⁇ 100 ⁇ m and 40 to 65% by weight a grain size ⁇ 50 ⁇ m. Certain deviations from this are irrelevant to the desulfurization effect.
- magnesium is added to the agent, which consists of calcium carbide and dried coal, so that the agent is pneumatically injected into the melt as a homogeneous mixture is promoted.
- the content of technical calcium carbide is preferably 47.5 to 95.5% by weight, particularly preferably 66 to 86% by weight, that of dried coal to 50 to 2% by weight, particularly preferably 20 to 4% by weight, and that of fine-grained Magnesium adjusted to 2.5 to 40% by weight, particularly preferably 10 to 30% by weight.
- This method of separate fluidization and co-blowing of the separately fluidized mixtures has the advantage that the magnesium can also be used in a coarser form.
- the desulfurization agent according to the invention is expediently blown into the molten iron as deeply as possible in a fluidized form with a conveying gas amount of 3 to 30 NL / kg medium.
- the delivery rate of the agent should be 10 to 100 kg / min; preferably a rate of 30 to 80 kg / min of desulfurizing agent is used.
- Non-oxidizing gases such as argon or nitrogen alone or as a mixture or dried air are preferably used as the conveying gas for the desulfurization agent.
- the desulfurization agent according to the invention has considerable advantages over previously known agents in connection with the method according to the invention. Apart from the small amount of ash it contains, the coal brings practically no other slag-forming components into the iron melt. This means that considerably less slag is obtained when using the desulfurization agent according to the invention than when using calcium carbonate or calcium hydroxide as gas-releasing additives.
- the coal Compared to the known hydrogen and carbon dioxide-releasing additives, the coal has the advantage that a sufficient amount of gas is developed immediately after entering the molten iron and thus practically complete dispersion of the finely divided calcium carbide and magnesium in the molten iron is achieved.
- the desulfurization effect of the agent according to the invention is known Desulfurization mixtures based on calcium carbide are superior.
- the agent according to the invention has the surprising advantage that the treatment times of the iron melts are reduced considerably, more than was expected after the reactivity of the magnesium and the calcium carbide.
- the desulfurization agent according to the invention is just as suitable in connection with the blowing process described for hot metal desulfurization in the open pan as in the torpedo pan.
- composition of the agent guarantees sufficient distribution so that a high degree of utilization of the desulfurizing agent is achieved.
- the treatment times of the iron melts are short, so that the melt is only slightly cooled.
- the amount of slag produced is small, which means that the iron losses when removing the slag are insignificant.
- Number 10 relates to a known desulfurization agent consisting of 50% by weight of magnesium and 50% by weight of ball mill dust (Al 2 O 2 and Al).
- Numbers 3 to 9 and 11 to 13 show the results obtained in open pans with compositions composed according to the invention.
- the means according to the invention are superior to the conventional means.
- the amount of gas split off in 1 / kg is the amount of gas that escapes when the coal is heated to crude iron temperature very quickly.
- the volatile constituents of the diamide lime are the amount of CO z released during carbonate decomposition.
- the duration of gas evolution indicates the time (sec) in which approximately 90% of the total amount of gas is split off.
Abstract
Ein feinkörniges Mitel zur Entschwefelung von Eisenschmelzen bestehend aus technischem Calciumcarbid, getrockneter Kohle mit einem Gehalt von mindestens 15 Gew.% flüchtigen Bestandteilen, die unmittelbar nach dem Eintritt in die Eisenschmelze mindestens 80 NL Gas/kg Kohle freisetzen, und gegebenenfalls feinkörnigem Magnesium. Zur Herstellung des Mittels geeignete Kohlen sind Braunkohle, Flamm-, Gasflamm-, Gas- oder Fettkohle. Die Herstellung des Mittels erfolgt durch Zugabe der getrockneten Kohle zum gegebenenfalls vorgebrochenen Calciumcarbid und gemeinsame Zerkleinerung auf eine Korngröße von 90 % < 200 µm. Das feinkörnige Magnesium ist in dem Mittel entweder gleichmäßig verteilt enthalten, oder es wird getrennt vom Carbid/Kohle-Gemisch gelagert, fluidisiert und während des Einblasens, gegebenenfalls zeitlich variiert, in der Förderleitung oder in der Lanze, dem Carbid/Kohle- Gemisch zudosiert.A fine-grained agent for the desulfurization of molten iron consisting of technical calcium carbide, dried coal with a content of at least 15% by weight of volatile constituents, which release at least 80 NL gas / kg coal immediately after entering the molten iron, and optionally fine-grained magnesium. Coals suitable for producing the agent are lignite, flame, gas flame, gas or fat coal. The agent is produced by adding the dried coal to the optionally pre-broken calcium carbide and comminuting it to a particle size of 90% <200 μm. The fine-grained magnesium is either contained in the agent in a uniform distribution, or it is stored separately from the carbide / coal mixture, fluidized and metered into the feed line or in the lance to the carbide / coal mixture during the blowing in, optionally with time.
Description
Die Erfindung betrifft Mittel, Verfahren zur Herstellung des Mittels und Anwendung des Mittels zur Entschwefelung von Eisenschmelzen außerhalb des Hochofens. Unter Eisenschmelzen werden hier Roheisen- und Gußeisenschmelzen verstanden.The invention relates to agents, processes for producing the agent and application of the agent for the desulfurization of molten iron outside the blast furnace. Here, iron smelting means pig iron and cast iron melting.
Die Entschwefelung des Roheisens außerhalb des Hochofens in der Transport- oder Umfüllpfanne gehört inzwischen zum Stand der Technik. Als bevorzugtes Entschwefelungsmittel haben sich Gemische auf Basis von Calciumcarbid durchgesetzt, da diese bei hoher Wirtschaftlichkeit eine schnelle Entschwefelung des Roheisens bewirken und zu niedrigen Endschwefelgehalten führen. Ein bevorzugtes Mittel stellt ein Gemisch bestehend aus 20 bis 90 Gew.% technischem Calciumcarbid und Calciumcarbonat, vorzugsweise in gefällter Form und 2 bis 20 Gew.% darin verteiltem Kohlenstoff dar, wobei das feinteilige Calciumcarbonat/ Kohlenstoff-Gemisch unter dem Namen Diamidkalk bekannt ist (DE-PS 17 58 250).The desulfurization of the pig iron outside the blast furnace in the transport or transfer ladle has become part of the state of the art. Mixtures based on calcium carbide have established themselves as the preferred desulfurizing agent, since these, with high economy, bring about rapid desulfurization of the pig iron and lead to low final sulfur contents. A preferred agent is a mixture consisting of 20 to 90% by weight technical calcium carbide and calcium carbonate, preferably in precipitated form and 2 to 20% by weight carbon distributed therein, the finely divided calcium carbonate / carbon mixture being known under the name diamide lime ( DE-PS 17 58 250).
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 Gew.% Aluminium- oder Magnesiumpulver, bezogen auf die Calciumverbindungen, verwendet.From DE-AS 25 31 047 a method for desulfurizing pig iron is known which uses a mixture of calcium carbide, calcium cyanamide or lime with a proportion of 0.5 to 3.5% by weight of aluminum or magnesium powder, based on that, as the desulfurization agent Calcium compounds used.
In der US-Patentschrift 3 998 625 wird ein Entschwefelungsmittel, bestehend aus einer Kombination von Kalk und weiteren Bestandteilen mit Magnesium beschrieben, sowie in der US-Patenschrift 4 266 969 der Einsatz von Kalk mit kohlenstoffhaltigem Material und einem nichtoxidierenden Fördergas empfohlen. Nachteilig bei den bekannten Mitteln sind die großen anfallenden Schlackenmengen, die besonders in den Torpedopfannen aber auch in den offenen Pfannen zu unerwünschten Ablagerungen und Verkrustungen führen und darüber hinaus beträchtliche Mengen Eisen einschließen, was zu erheblichen Eisenverlusten führt.US Pat. No. 3,998,625 describes a desulfurization agent consisting of a combination of lime and other constituents with magnesium, and US Pat. No. 4,266,969 recommends the use of lime with carbon-containing material and a non-oxidizing production gas. A disadvantage of the known agents is the large amounts of slag which lead to undesirable deposits and incrustations, particularly in the torpedo pans but also in the open pans, and moreover include considerable amounts of iron, which leads to considerable iron losses.
Es ist auch bereits vorgeschlagen worden, statt Calciumcarbonat dem Calciumcarbid einen Zusatz zuzumischen, der bei der Temperatur der Eisenschmelze Wasserstoff abspaltet (DE-PS 22 52 796). Ein derartiges Entschwefelungsmittel hat sich jedoch in der Praxis nicht bewährt, da offenbar die Abspaltung des Wasserstoffes nicht in der Weise erfolgte, daß eine ausreichende Dispergierung des Calciumcarbids in der Eisenschmelze bewirkt werden konnte.Instead of calcium carbonate, it has also already been proposed to add an addition to the calcium carbide which releases hydrogen at the temperature of the molten iron (DE-PS 22 52 796). However, such a desulfurization agent has not proven itself in practice, since apparently the hydrogen was not split off in such a way that sufficient dispersion of the calcium carbide in the iron melt could be brought about.
Entschwefelungsmittel bei der Behandlung von Gußeisenschmelzen zusammen mit Kohlenstoff, z. B. in Form von Pechkoks, Blutkohle, Lederkohle einzusetzen,
aber die hierzu vorgeschlagenen Kohlensorten enthalten praktisch keine flüchtigen Bestandteile (s. angegebenen Stand der Technik in der DE-PS 17 58 250).Desulfurizing agent in the treatment of cast iron melts together with carbon, e.g. B. in the form of pitch coke, blood coal, leather coal,
but the coal types proposed for this purpose contain practically no volatile constituents (see the prior art indicated in DE-PS 17 58 250).
Es bestand daher die Aufgabe, ein Entschwefelungsmittel auf Basis von Calciumcarbid zu entwickeln, das einerseits keine weiteren schlackebildenden Bestandteile in die Eisenschmelze einbringt und andererseits eine für die Dispergierung des Calciumcarbids ausreichend große Gasmenge unmittelbar nach dem Eintritt in die Eisenschmelze entwickelt und bei günstigen Verbrauchswerten und kurzen Behandlungszeiten niedrige Endschwefelgehalte erzielt. Gelöst wurde diese Aufgabe durch ein feinkörniges Mittel, das in fluidisierter Form mittels eines Gases in die Eisenschmelze eingeblasen wird, das aus einem Gemisch von technischem Calciumcarbid und einer getrockneten Kohle besteht, welche mindestens 15 Gew.% flüchtige Bestandteile enthält und unmittelbar nach dem Eintritt in die Eisenschmelze ein Gasvolumen von mindestens 80 NL Gas/kg Kohle freisetzt.It was therefore the task to develop a desulphurization agent based on calcium carbide which, on the one hand, does not introduce any further slag-forming constituents into the iron melt and, on the other hand, develops a gas quantity which is sufficient for the dispersion of the calcium carbide immediately after entering the iron melt and with favorable consumption values and short Treatment times achieved low final sulfur levels. This object was achieved by means of a fine-grained agent which is blown into the molten iron in fluidized form by means of a gas which consists of a mixture of technical calcium carbide and a dried coal which contains at least 15% by weight of volatile constituents and immediately after entering the iron melt releases a gas volume of at least 80 NL gas / kg coal.
Unter technischem Calciumcarbid wird ein handelsübliches Produkt verstanden, das 65 bis 85 Gew.% CaCz enthält und dessen Rest überwiegend aus Kalk besteht. Der Anteil an technischem Calciumcarbid kann in dem erfindungsgemäßen Mittel in weiten Grenzen schwanken. Dementsprechend schwanken die Gehalte der übrigen Bestandteile.Technical calcium carbide is understood to mean a commercial product which contains 65 to 85% by weight of CaC z and the rest of which consists predominantly of lime. The proportion of technical calcium carbide can vary within wide limits in the agent according to the invention. The contents of the remaining components fluctuate accordingly.
Bevorzugt wird ein Entschwefelungsmittel verwendet, das 50 bis 98 Gew.% Calciumcarbid und 50 bis 2 Gew.% Kohle enthält. Besonders bevorzugt enthält das Mittel 80 bis 96 Gew.% Calciumcarbid und 20 bis 4 Gew.% Kohle.A desulfurization agent is preferably used which contains 50 to 98% by weight calcium carbide and 50 to 2% by weight coal. The agent particularly preferably contains 80 to 96% by weight of calcium carbide and 20 to 4% by weight of coal.
Das erfindungsgemäße Entschwefelungsmittel kann zusätzlich Magnesium enthalten. Bevorzugt sind Mischungen mit Gehalten von 47,5 bis 95,5 Gew.% technischem Calciumcarbid, 50 bis 2 Gew.% getrockneter Kohle und 2 bis 40 Gew.% Magnesium.The desulfurization agent according to the invention can additionally contain magnesium. Mixtures with contents of 47.5 to 95.5% by weight of technical calcium carbide, 50 to 2% by weight of dried coal and 2 to 40% by weight of magnesium are preferred.
Bevorzugt wird als Kohlekomponente eine Kohlesorte gewählt, die als getrocknetes Produkt beim pneumatischen Einbringen in die Eisenschmelze, d. h. bei einer Erhitzungsgeschwindigkeit von 103 bis 106°C/sec. etwa 90 Gew.-% der flüchtigen Bestandteile innerhalb von weniger als 60 sec., bevorzugt weniger als 40 sec., freisetzt. Je höher der Anteil an flüchtigen Bestandteilen in der Kohle ist, umso höher ist im allgemeinen die Wirksamkeit des Entschwefelungsmittels. Besonders bevorzugt werden daher Kohlen verwendet, die wenigstens 25 Gew.-% flüchtige Bestandteile enthalten.A coal type is preferably selected as the carbon component, which as the dried product is pneumatically introduced into the molten iron, ie at a heating rate of 10 3 to 10 6 ° C / sec. releases about 90% by weight of the volatile constituents within less than 60 seconds, preferably less than 40 seconds. Generally, the higher the volatile content in the coal, the higher the effectiveness of the desulfurization agent. Coals containing at least 25% by weight of volatile constituents are therefore particularly preferably used.
Bevorzugt werden Kohlen verwendet, die in getrockneter Form unmittelbar nach dem Eintritt in die Eisenschmelze ein Gasvolumen von mindestens 150 NL/kg entwickeln. Kohlen, die diese Bedingungen erfüllen, sind insbesondere Braunkohlen, Flammkohle, Gasflammkohle, Gaskohle und Fettkohle (vgl. Tabelle 1).Coals are preferably used which develop a gas volume of at least 150 NL / kg in the dried form immediately after entering the iron melt. Coals that meet these conditions are in particular lignite, flame coal, gas flame coal, gas coal and fat coal (see Table 1).
Sollte es sich als zweckmäßig erweisen, können auch zwei oder mehrere Kohlesorten mit hohen Gehalten an flüchtigen Bestandteilen im Gemisch verwendet werden.If it proves expedient, two or more types of coal with high volatile constituents can also be used in the mixture.
Der Feuchtigkeitsgehalt der getrockneten Kohle beträgt bevorzugt weniger als 0,5 Gew.-%, um eine Acetylenbildung durch Reaktion mit dem Calciumcarbid auszuschliessen. Erreicht werden solche Trocknungsgrade in handelsüblichen Trockenvorrichtungen wie Drallstrom-, Flugstrom-oder Mahltrockner sowie beim Trocknen im Vakuum in einfachen Aggregaten, worin das zu trocknende Gut lediglich umgewälzt wird.The moisture content of the dried coal is preferably less than 0.5% by weight in order to prevent acetylene formation by reaction with the calcium carbide. Such degrees of dryness are achieved in commercially available drying devices such as swirl flow driers, entrained flow driers or grinding driers and when drying in a vacuum in simple units, in which the material to be dried is merely circulated.
Das zu verwendende Magnesium sollte eine Körnung kleiner 1 mm besitzen. Bevorzugt wird ein Magnesium verwendet, das bereits < 500 um zerkleinert ist, besonders bevorzugt wird ein Magnesium, das eine Korngröße <350 µm besitzt.The magnesium to be used should have a grain size of less than 1 mm. A magnesium is preferably used which has already been comminuted <500 μm, particularly preferred is a magnesium which has a grain size <350 μm.
Es kann sich als zweckmäßig erweisen, dem Entschwefelungsgemisch einen Anteil von 1 bis 10 Gew.% Flußspat beizumischen z. B. um die Eigenschaften der bei der Entschwefelungsbehandlung entstehende Schlacke günstig zu beeinflussen. Bevorzugt werden dem Gemisch 2 bis 6 Gew.% Flußspat zugemischt. Anstelle von Flußspat kann dem Mittel Kugelmühlenstaub (Abfälle aus der Aluminiumherstellung), bestehend aus Aluminiumoxid mit Anteilen von bis zu 30 Gew.% Aluminium zugesetzt werden. Die Herstellung des erfindungsgemäßen Entschwefelungsmittels erfolgt in der Weise, daß die getrocknete Kohle dem vorgebrochenen oder vorgemahlenen Calciumcarbid zudosiert und das Gemisch in einer Mühle auf den gewünschten Feinheitsgrad zerkleinert wird. Hierbei kann es sich als zweckmäßig erweisen, unter Inertgasdeckung zu arbeiten, um evtl. entstehende geringe Acetylenmengen aus der Misch- und Mahlanlage sofort zu entfernen. Man kann aber auch das Carbid und die Kohle getrennt vermahlen und nachträglich zusammenmischen.It may prove expedient to add a proportion of 1 to 10% by weight of fluorspar to the desulfurization mixture, e.g. B. to favorably influence the properties of the slag formed during the desulfurization treatment. Preferably 2 to 6% by weight of fluorspar is added to the mixture. Instead of fluorspar, ball mill dust (waste from aluminum production) consisting of aluminum oxide with proportions of up to 30% by weight aluminum can be added to the agent. The desulfurization agent according to the invention is produced in such a way that the dried coal is metered into the pre-broken or pre-ground calcium carbide and the mixture is ground in a mill to the desired degree of fineness. It can be useful to work under an inert gas blanket in order to remove any small amounts of acetylene from the mixing and grinding plant. However, the carbide and the coal can also be ground separately and subsequently mixed together.
Die Bestandteile des erfindungsgemäßen Mittels mit Ausnahme von Magnesium, werden
intensiv vermahlen und gemischt, wobei diese bevorzugt so weit zerkleinert werden, daß mindestens 90 Gew.-% des Gemisches eine Korngreße <200 µm, besonders bevorzugt aber 90 % eine Korngröße < 100 um und 40 bis 65 Gew.-% eine Korngröße < 50 µm, aufweisen. Gewisse Abweichungen hiervon sind ohne Belang auf den Entschwefelungseffekt.The components of the agent according to the invention, with the exception of magnesium, are
intensively ground and mixed, these preferably being comminuted to such an extent that at least 90% by weight of the mixture has a grain size <200 μm, but particularly preferably 90% a grain size <100 μm and 40 to 65% by weight a grain size <50 µm. Certain deviations from this are irrelevant to the desulfurization effect.
In einer bevorzugten Ausführungsform wird dem Mittel, das aus Calciumcarbid und getrockneter Kohle besteht, Magnesium zudosiert, so daß das Mittel als homogenes Gemisch pneumatisch in die Schmelze gefördert wird. Bevorzugt wird der Gehalt an technischem Calciumcarbid auf 47,5 bis 95,5 Gew.% besonders bevorzugt 66 bis 86 Gew.%, der an getrockneter Kohle auf 50 bis 2 Gew.% besonders bevorzugt 20 bis 4 Gew.% und der an feinkörnigem Magnesium auf 2,5 bis 40 Gew.% besonders bevorzugt 10 bis 30 Gew.% eingestellt. Andererseits hat es sich häufig als zweckmäßig erwiesen, das Carbid/Kohle-Gemisch nach seiner Herstellung getrennt vom Magnesium zu lagern, zu fluidisieren und beide Bestandteile erst in der Förderleitung oder in der Lanze zu vereinigen und auf diese Weise gemeinsam in die Schmelze einzubringen. Dieses Verfahren der getrennten Fluidisierung und des gemeinsamen Einblasens der getrennt flüidisierten Gemische (Coinjection) hat den Vorteil, daß das Magnesium auch in gröberer Form verwendet werden kann.In a preferred embodiment, magnesium is added to the agent, which consists of calcium carbide and dried coal, so that the agent is pneumatically injected into the melt as a homogeneous mixture is promoted. The content of technical calcium carbide is preferably 47.5 to 95.5% by weight, particularly preferably 66 to 86% by weight, that of dried coal to 50 to 2% by weight, particularly preferably 20 to 4% by weight, and that of fine-grained Magnesium adjusted to 2.5 to 40% by weight, particularly preferably 10 to 30% by weight. On the other hand, it has often proven expedient to store the carbide / coal mixture separately from the magnesium after its production, to fluidize it and to combine both components only in the delivery line or in the lance and in this way to introduce them together into the melt. This method of separate fluidization and co-blowing of the separately fluidized mixtures (Coinjection) has the advantage that the magnesium can also be used in a coarser form.
Das erfindungsgemäße Entschwefelungsmittel wird zweckmäßigerweise in fluidisierter Form mit einer Fördergasmenge von 3 bis 30 NL/kg Mittel so tief wie möglich in die Eisenschmelze eingeblasen. Hierbei soll die Förderrate des Mittels 10 bis 100 kg/min betragen; bevorzugt wird mit einer Förderrate von 30 bis 80 kg/min Entschwefelungsmittel gearbeitet.The desulfurization agent according to the invention is expediently blown into the molten iron as deeply as possible in a fluidized form with a conveying gas amount of 3 to 30 NL / kg medium. The delivery rate of the agent should be 10 to 100 kg / min; preferably a rate of 30 to 80 kg / min of desulfurizing agent is used.
Als Fördergas für das Entschwefelungsmittel verwendet man vorzugsweise nichtoxidierende Gase wie Argon oder Stickstoff allein oder als Gemisch oder getrocknete Luft.Non-oxidizing gases such as argon or nitrogen alone or as a mixture or dried air are preferably used as the conveying gas for the desulfurization agent.
Das erfindungsgemäße Entschwefelungsmittel weist in Verbindung mit dem erfindungsgemäßen Verfahren erhebliche Vorteile gegenüber bisher bekannten Mitteln auf. So bringt die Kohle, abgesehen von der in ihr enthaltenen geringen Aschemenge praktisch keine weiteren schlackebildenden Bestandteile in die Eisenschmelze ein. Damit fällt bei Einsatz des erfindungsgemäßen Entschwefelungsmittels erheblich weniger Schlacke an als bei der Verwendung von Calciumcarbonat oder Calciumhydroxid als gasabspaltende Zusätze.The desulfurization agent according to the invention has considerable advantages over previously known agents in connection with the method according to the invention. Apart from the small amount of ash it contains, the coal brings practically no other slag-forming components into the iron melt. This means that considerably less slag is obtained when using the desulfurization agent according to the invention than when using calcium carbonate or calcium hydroxide as gas-releasing additives.
Im Vergleich zu den bekannten Wasserstoff und Kohlendioxid abspaltenden Zusätzen hat die Kohle den Vorteil, daß eine ausreichende Gasmenge unmittelbar nach dem Eintritt in die Eisenschmelze entwickelt und damit eine praktisch vollständige Dispergierung des feinteiligen Calciumcarbids und des Magnesiums in der Eisenschmelze erreicht wird. Hierdurch ist die Entschwefelungswirkung des erfindungsgemäßen Mittels den bekannten Entschwefelungsgemischen auf Basis Calciumcarbid gegenüber überlegen.Compared to the known hydrogen and carbon dioxide-releasing additives, the coal has the advantage that a sufficient amount of gas is developed immediately after entering the molten iron and thus practically complete dispersion of the finely divided calcium carbide and magnesium in the molten iron is achieved. As a result, the desulfurization effect of the agent according to the invention is known Desulfurization mixtures based on calcium carbide are superior.
Gegenüber bekannten Entschwefelungsgemischen mit Gehalten von 50 Gew.% und mehr Magnesium, beinhaltet das erfindungsgemäße Mittel den überraschenden Vorteil, daß die Behandlungszeiten der Eisenschmelzen erheblich reduziert werden und zwar stärker als es nach der Reaktionsfähigkeit des Magnesiums und des Calciumcarbids zu erwartender war.Compared to known desulfurization mixtures with a content of 50% by weight or more of magnesium, the agent according to the invention has the surprising advantage that the treatment times of the iron melts are reduced considerably, more than was expected after the reactivity of the magnesium and the calcium carbide.
Das erfindungsgemäße Entschwefelungsmittel eignet sich im Zusammenhang mit dem beschriebenen Einblasverfahren ebenso gut zur Roheisenentschwefelung in der offenen Pfanne wie in der Torpedopfanne.The desulfurization agent according to the invention is just as suitable in connection with the blowing process described for hot metal desulfurization in the open pan as in the torpedo pan.
Darüberhinaus ist der besonders geringe Bedarf an Einblasgas vorteilhaft. Die Zusammensetzung des Mittels garantiert eine ausreichende Verteilung, so daß ein hoher Ausnutzungsgrad des Entschwefelungsmittels erreicht wird.In addition, the particularly low requirement for injection gas is advantageous. The composition of the agent guarantees sufficient distribution so that a high degree of utilization of the desulfurizing agent is achieved.
Bei Anwendung des erfindungsgemäßen Mittels bzw. Verfahrens wird eine deutliche Steigerung des Entschwefelungsgrades erreicht bzw. es wird eine merklich verringerte Menge an Entschwefelungsmittel zur Erzielung der gleichen Entschwefelungswirkung benötigt.When the agent or method according to the invention is used, a significant increase in the degree of desulfurization is achieved or a markedly reduced amount of desulfurizing agent is required to achieve the same desulfurization effect.
Bei Anwendung des erfindungsgemäßen Entschwefelungmittels sind die Behandlungszeiten der Eisenschmelzen kurz, so daß auch nur eine geringe Abkühlung der Schmelze erfolgt. Die entstehenden Schlackemengen sind gering, wodurch die Eisenverluste beim Abziehen der Schlacke unbedeutend sind.When using the desulfurization agent according to the invention, the treatment times of the iron melts are short, so that the melt is only slightly cooled. The amount of slag produced is small, which means that the iron losses when removing the slag are insignificant.
Die nachfolgenden Beispiele sollen die Erfindung näher erläutern.The following examples are intended to explain the invention in more detail.
In Tabelle 2 sind unter den laufenden Nummern 1 und 2 die Ergebnisse dargestellt, die mit herkömmlichen Entschwefelungsmitteln auf Basis von Calciumcarbid und Diamidkalk in der offenen Pfanne erhalten wurden. Die Nummer 10 betrifft ein bekanntes Entschwefelungsmittel bestehend aus 50 Gew.% Magnesium und 50 Gew.% Kugelmühlenstaub (Al2O2 u. Al).In Table 2, the numbers 1 and 2 show the results obtained with conventional desulfurization agents based on calcium carbide and diamide lime in the open pan. Number 10 relates to a known desulfurization agent consisting of 50% by weight of magnesium and 50% by weight of ball mill dust (Al 2 O 2 and Al).
Unter den Nummern 3 bis 9 und 11 bis 13 sind die Ergebnisse wiedergegeben, die mit erfindungsgemäß zusammengesetzten Mitteln in offenen Pfannen erhalten wurden.Numbers 3 to 9 and 11 to 13 show the results obtained in open pans with compositions composed according to the invention.
Die in Tabelle 3 wiedergegebenen Ergebnisse sind diejenigen von in Torpedopfannen erhaltenen Entschwefelungsbehandlungen mit den unter 1 bis 6 angegebenen Gemischen.The results shown in Table 3 are those of desulfurization treatments obtained in torpedo pans with the mixtures given under 1 to 6.
Sowohl beim Arbeiten in der offenen Pfanne als auch beim Arbeiten in der Torpedopfanne zeigen sich die erfindungsgemäßen Mittel den herkömmlichen Mitteln überlegen.Both when working in the open pan and when working in the torpedo pan, the means according to the invention are superior to the conventional means.
Die in Tabelle 2 verwendeten Abkürzungen bedeuten:
Die abgespaltene Gasmenge in 1/kg ist diejenige Gasmenge, die bei sehr schnellem Erhitzen der Kohle auf Roheisentemperatur entweicht.The amount of gas split off in 1 / kg is the amount of gas that escapes when the coal is heated to crude iron temperature very quickly.
Unter den flüchtigen Bestandteilen des Diamidkalks versteht man die bei der Carbonatzersetzung freiwerdende COz-Menge.The volatile constituents of the diamide lime are the amount of CO z released during carbonate decomposition.
Die Zeitdauer der Gasentwicklung gibt an, in welcher Zeit (Sec) etwa 90 % der gesamten Gasmenge abgespalten werden.
Claims (23)
dadurch gekennzeichnet , daß es im wesentlichen aus technischem Calciumcarbid und einer getrockneten Kohle, die mindestens 15 Gew.-% flüchtige Bestandteile enthält und bei der Temperatur der Eisenschmelze ein Gasvolumen von mindestens 80 NL Gas/kg entwickelt, besteht.1. fine-grained agent for the desulphurization of molten iron based on calcium carbide, which is blown into the molten iron in fluidized form by means of a gas,
characterized in that it consists essentially of technical calcium carbide and a dried coal which contains at least 15% by weight of volatile constituents and develops a gas volume of at least 80 NL gas / kg at the temperature of the molten iron.
gekennzeichnet , daß es 50 bis 98 Gew.-% Calciumcarbid und 50 bis 2 Gew.-% Kohle enthält.2. Composition according to claim 1, characterized
characterized in that it contains 50 to 98 wt .-% calcium carbide and 50 to 2 wt .-% coal.
dadurch gekennzeichnet , daß bei einer Erhitzungsgeschwindigkeit der Kohle von 103 bis 106°C/sec. auf die Temperatur der Eisenschmelze etwa 90 Gew.-% der flüchtigen Bestandteile innerhalb von weniger als 60 sec., bevorzugt weniger als 40 sec., freigesetzt werden.4. Agent according to one of the preceding claims,
characterized in that at a heating rate of the coal of 10 3 to 10 6 ° C / sec. to the temperature of the molten iron, about 90% by weight of the volatile constituents are released within less than 60 seconds, preferably less than 40 seconds.
dadurch gekennzeichnet , daß die flüchtigen Bestandteile der Kohle bei der Temperatur der Eisenschmelze innerhalb von weniger als 10 sec. abgespalten werden.5. Agent according to one of the preceding claims,
characterized in that the volatile constituents of the coal are split off at the temperature of the molten iron within less than 10 seconds.
dadurch gekennzeichnet , daß es zusätzlich Magnesium enthält.6. Composition according to one of the preceding claims,
characterized in that it additionally contains magnesium.
gekennzeichnet , daß es 67,5 bis 95,5 Gew.-% Calciumcarbid, 50 bis 2 Gew.-% Kohle und 2,5 bis 40 Gew.-% Magnesium enthält.7. Composition according to claim 6, characterized
characterized in that it contains 67.5 to 95.5 wt .-% calcium carbide, 50 to 2 wt .-% coal and 2.5 to 40 wt .-% magnesium.
gekennzeichnet, daß der Gehalt an Calciumcarbid 66 bis 86 Gew.-%, an getrockneter Kohle 20 bis 4 Gew.-% und an feinkörnigem Magnesium 10 bis 30 Gew.-% beträgt.8. Composition according to claim 6 or 7, characterized
characterized in that the content of calcium carbide is 66 to 86 wt .-%, of dried coal 20 to 4 wt .-% and of fine-grained magnesium 10 to 30 wt .-%.
durch eine Kohle, welche nach dem Eintritt in die Eisenschmelze ein Gasvolumen von mindestens 150 NL Gas/kg Kohle freisetzt.9. Means according to one or more of the preceding claims, characterized
by a coal, which releases a gas volume of at least 150 NL gas / kg coal after entering the iron smelter.
gekennzeichnet , daß der Feuchtigkeitsgehalt der getrockneten Kohle weniger als 0,5 Gew.-% beträgt.10. Composition according to one or more of the preceding claims, characterized
characterized in that the moisture content of the dried coal is less than 0.5 wt .-%.
gekennzeichnet , daß die getrocknete Kohle mindestens 25 Gew.-% flüchtige Bestandteile enthält.11. Composition according to one or more of the preceding claims, characterized
characterized in that the dried coal contains at least 25 wt .-% volatile constituents.
dadurch gekennzeichnet , daß die Kohle eine Braunkohle ist.12. Composition according to one of the preceding claims,
characterized in that the coal is lignite.
dadurch gekennzeichnet , daß man Kohle aus der Gruppe, bestehend aus Flammkohle, Gasflammkohle und Gaskohle auswählt.13. Composition according to one of claims 1 to 11,
characterized in that coal is selected from the group consisting of flame coal, gas flame coal and gas coal.
dadurch gekennzeichnet , daß mindestens 90 Gew.-% des Gemisches eine Korngröße < 200 µm aufweisen.14. Composition according to one of the preceding claims,
characterized in that at least 90% by weight of the mixture have a grain size <200 µm.
dadurch gekennzeichnet , daß mindestens 90 Gew.-% des Gemisches eine Korngröße < 100 µm und 40 bis 65 Gew.-% eine Korngröße <50 µm aufweisen.15. Composition according to one of the preceding claims,
characterized in that at least 90% by weight of the mixture have a grain size <100 µm and 40 to 65% by weight a grain size <50 µm.
gekennzeichnet , daß das Gemisch einen Anteil von 1 bis 10 Gew.-% Flußspat enthält.16. Composition according to one or more of the preceding claims, characterized
characterized in that the mixture contains a proportion of 1 to 10 wt .-% fluorspar.
gekennzeichnet , daß das Gemisch 2 bis 6 Gew.-% Flußspat enthält.17. Composition according to one or more of the preceding claims, characterized
characterized in that the mixture contains 2 to 6 wt .-% fluorspar.
gekennzeichnet , daß man die Kohle trocknet, dem vorgebrochenen Calciumcarbid zudosiert und das Gemisch in einer Mühle auf den gewünschten Feinheitsgrad zerkleinert.18. A process for the preparation of the agent according to any one of claims 1 to 17, characterized
characterized in that the coal is dried, the pre-broken calcium carbide is metered in and the mixture is ground in a mill to the desired degree of fineness.
daß das Entschwefelungsmittel nach einem oder mehreren der Ansprüche 1 bis 17 in fluidisierter Form mit einer Fördergasmenge von 3 bis 30 NL/kg Mittel in die Eisenschmelze eingeblasen wird.19. Process for the desulfurization of molten iron, characterized in that
that the desulfurization agent according to one or more of claims 1 to 17 is blown into the molten iron in fluidized form with a conveying gas amount of 3 to 30 NL / kg agent.
gekennzeichnet, daß man als Fördergas wenigstens ein nichtoxidierendes Gas aus der Gruppe Stickstoff, Argon, Erdgas und Propan verwendet.21. The method according to claim 19 or 20, characterized
characterized in that at least one non-oxidizing gas from the group consisting of nitrogen, argon, natural gas and propane is used as the conveying gas.
gekennzeichet, daß man das feinteilige Magnesium und das Carbid-Kohlegemisch getrennt lagert, fluidisiert und danach in der Förderleitung oder Lanze vereinigt.22. The method according to claims 19 to 21, characterized
marked that the finely divided magnesium and the carbide-carbon mixture are stored separately, fluidized and then combined in the delivery line or lance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT86117417T ATE54673T1 (en) | 1985-12-17 | 1986-12-15 | AGENT FOR DESULPHURIZATION OF MOLTEN IRON AND METHOD OF MANUFACTURE OF THE AGENT. |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19853544562 DE3544562C2 (en) | 1985-12-17 | 1985-12-17 | Fine-grained agent for the desulfurization of molten iron |
| DE3544562 | 1985-12-17 | ||
| DE3544563 | 1985-12-17 | ||
| DE3544563A DE3544563C2 (en) | 1985-12-17 | 1985-12-17 | Means for desulfurizing molten iron |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0226994A1 true EP0226994A1 (en) | 1987-07-01 |
| EP0226994B1 EP0226994B1 (en) | 1990-07-18 |
Family
ID=25838925
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP86117417A Expired - Lifetime EP0226994B1 (en) | 1985-12-17 | 1986-12-15 | Agent for desulphuration of molten iron and process for its production |
Country Status (11)
| Country | Link |
|---|---|
| US (2) | US4764211A (en) |
| EP (1) | EP0226994B1 (en) |
| JP (1) | JPH0645813B2 (en) |
| CN (1) | CN1006809B (en) |
| AU (1) | AU571147B2 (en) |
| BR (1) | BR8606249A (en) |
| CA (1) | CA1261633A (en) |
| DE (1) | DE3672779D1 (en) |
| ES (1) | ES2016557B3 (en) |
| FI (1) | FI83095C (en) |
| NO (1) | NO168057C (en) |
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| DE3831831C1 (en) * | 1988-09-20 | 1989-11-02 | Skw Trostberg Ag, 8223 Trostberg, De | |
| EP0387580A1 (en) * | 1989-03-13 | 1990-09-19 | Hoechst Aktiengesellschaft | Agent and method for desulfurizing molten metals |
| EP0467545A2 (en) * | 1990-07-05 | 1992-01-22 | REACTIVE METALS & ALLOYS CORPORATION | Iron desulfurization additive and method for introduction into hot metals |
| DE4242328A1 (en) * | 1992-12-15 | 1994-06-16 | Alfred Dipl Ing Dr Freissmuth | Agents for aftertreatment, preferably for desulfurization, of raw and cast iron melts based on alkali-containing and gas-releasing raw materials |
| WO1995033859A1 (en) * | 1994-06-08 | 1995-12-14 | Donau Chemie Aktiengesellschaft | Desulphurizing agent for crude-iron and casting-iron melts, and method of producing it |
| WO1996017963A1 (en) * | 1994-12-09 | 1996-06-13 | Donau Chemie Aktiengesellschaft | Agent for treating pig or cast iron melts for desulphurisation purposes |
| US8507010B2 (en) | 2008-05-21 | 2013-08-13 | Shanghai Allist Pharmaceuticals, Inc. | Compositions comprising quinazoline derivatives |
| US10190183B2 (en) | 2011-10-20 | 2019-01-29 | Almamet Gmbh | Method for desulfurizing |
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| DE3734877C1 (en) * | 1987-10-15 | 1988-10-27 | Sueddeutsche Kalkstickstoff | Means and methods for embroidering cast iron |
| US4941914A (en) * | 1989-05-18 | 1990-07-17 | Elkem Metals Company | Desulfurization agent |
| US5078784A (en) * | 1990-03-14 | 1992-01-07 | Elkem Metals Company | Desulfurization agent |
| US5002733A (en) * | 1989-07-26 | 1991-03-26 | American Alloys, Inc. | Silicon alloys containing calcium and method of making same |
| US5149364A (en) * | 1990-03-14 | 1992-09-22 | Elkem Metals Company | Desulfurization agent |
| UA32411C2 (en) * | 1991-08-28 | 2000-12-15 | Тіссен Шталь Аг | Mehtod for treatment of blast furnace cast iron melts in the tank (variants) |
| CA2054244C (en) * | 1991-10-25 | 2000-08-01 | Bruce James Barker | Powdered desulfurizing reagent and process of use |
| US5358550A (en) * | 1992-10-26 | 1994-10-25 | Rossborough Manufacturing Company | Desulfurization agent |
| US5873924A (en) * | 1997-04-07 | 1999-02-23 | Reactive Metals & Alloys Corporation | Desulfurizing mix and method for desulfurizing molten iron |
| US6372014B1 (en) | 2000-04-10 | 2002-04-16 | Rossborough Manufacturing Co. L.P. | Magnesium injection agent for ferrous metal |
| US6352570B1 (en) | 2000-04-10 | 2002-03-05 | Rossborough Manufacturing Co., Lp | Magnesium desulfurization agent |
| US6770115B2 (en) * | 2002-10-18 | 2004-08-03 | Remacor, Inc. | Process for magnesium granules |
| US6989040B2 (en) * | 2002-10-30 | 2006-01-24 | Gerald Zebrowski | Reclaimed magnesium desulfurization agent |
| US20050056120A1 (en) * | 2003-09-15 | 2005-03-17 | Flores-Morales Jose Ignacio | Desulphurization of ferrous materials using sodium silicate |
| US20050066772A1 (en) * | 2003-09-26 | 2005-03-31 | Flores-Morales Jose Ignacio | Desulphurization of ferrous materials using glass cullet |
| US7731778B2 (en) * | 2006-03-27 | 2010-06-08 | Magnesium Technologies Corporation | Scrap bale for steel making process |
| US20080196548A1 (en) * | 2007-02-16 | 2008-08-21 | Magnesium Technologies Corporation | Desulfurization puck |
| DE202014100884U1 (en) | 2014-02-26 | 2014-03-13 | Almamet Gmbh | Slag conditioner for desulfurization in secondary metallurgy of steel |
| CN112391510A (en) * | 2020-10-29 | 2021-02-23 | 张家港宏昌钢板有限公司 | Novel molten iron desulphurization process |
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- 1986-12-15 EP EP86117417A patent/EP0226994B1/en not_active Expired - Lifetime
- 1986-12-15 ES ES86117417T patent/ES2016557B3/en not_active Expired - Lifetime
- 1986-12-16 FI FI865126A patent/FI83095C/en not_active IP Right Cessation
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| DE3831831C1 (en) * | 1988-09-20 | 1989-11-02 | Skw Trostberg Ag, 8223 Trostberg, De | |
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| US8507010B2 (en) | 2008-05-21 | 2013-08-13 | Shanghai Allist Pharmaceuticals, Inc. | Compositions comprising quinazoline derivatives |
| US10190183B2 (en) | 2011-10-20 | 2019-01-29 | Almamet Gmbh | Method for desulfurizing |
Also Published As
| Publication number | Publication date |
|---|---|
| AU571147B2 (en) | 1988-03-31 |
| NO168057C (en) | 1992-01-08 |
| CN1006809B (en) | 1990-02-14 |
| FI865126A0 (en) | 1986-12-16 |
| JPH02163308A (en) | 1990-06-22 |
| NO168057B (en) | 1991-09-30 |
| NO865074D0 (en) | 1986-12-16 |
| US4832739A (en) | 1989-05-23 |
| FI865126A (en) | 1987-06-18 |
| CA1261633A (en) | 1989-09-26 |
| FI83095C (en) | 1991-05-27 |
| FI83095B (en) | 1991-02-15 |
| JPH0645813B2 (en) | 1994-06-15 |
| DE3672779D1 (en) | 1990-08-23 |
| BR8606249A (en) | 1987-09-29 |
| US4764211A (en) | 1988-08-16 |
| NO865074L (en) | 1987-06-18 |
| CN86108525A (en) | 1987-07-29 |
| ES2016557B3 (en) | 1990-11-16 |
| EP0226994B1 (en) | 1990-07-18 |
| AU6616786A (en) | 1987-06-18 |
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