EP0061012A1 - Process for producing desulfurizing agents for pig iron and steel melts - Google Patents
Process for producing desulfurizing agents for pig iron and steel melts Download PDFInfo
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- EP0061012A1 EP0061012A1 EP82101428A EP82101428A EP0061012A1 EP 0061012 A1 EP0061012 A1 EP 0061012A1 EP 82101428 A EP82101428 A EP 82101428A EP 82101428 A EP82101428 A EP 82101428A EP 0061012 A1 EP0061012 A1 EP 0061012A1
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- cac
- calcium oxide
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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
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/064—Dephosphorising; Desulfurising
- C21C7/0645—Agents used for dephosphorising or desulfurising
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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 a mixture for desulfurizing metal melts, in particular steel and pig iron melts, on the basis of CaC 2 -CaO crystal mixtures obtained in the melt flow, and to a method for producing the mixture.
- the known desulfurization mixtures especially for use by the immersion lance method, first had to be ground as finely as possible. According to this, these mixtures meet the requirements, but are expensive both in terms of manufacture and in terms of electrical energy consumption. Despite the fine grinding, relatively large amounts of the desulfurization mixtures had to be added in order to achieve the desired degree of desulfurization.
- the object of the present invention is therefore to create a desulfurization mixture which offers a better degree of utilization and to provide an economical process for the production of this mixture.
- the mixtures contain free carbon and carbonate and that part of the CaO 2 -CaO crystal mixture is hydrated to Ca (OH) 2 .
- CaC 2 -CaO crystal mixtures with a proportion of 40 to 80% by weight Ca0 (corresponding to 20 to 60% by weight CaC 2 ), in particular 45 to 80% by weight Ca0 (corresponding to 20 to 55% by weight CaC 2 ) or 40 to 65 wt% Ca0 (corresponding to 35 to 60 wt% CaC 2 ).
- the mixture according to the invention is furthermore preferably characterized in that it contains 1 to 6% by weight, preferably 2.5 to 3.5% by weight, of water chemically bound to calcium oxide.
- the mixtures of the invention preferably contain 0.5 to 8% by weight of free carbon (for example coke breeze, anthracite, graphite, carbon black) and 0.5 to 20% by weight of carbonates of calcium, magnesium or Sodium.
- free carbon for example coke breeze, anthracite, graphite, carbon black
- Ca0 and CaC 2 crystallize as a crystal mixture in which the CaC 2 and CaO crystals are intertwined, namely at the specified CaC 2 / CaO quantity ratio with a lying in the area of the eutectic or shifted to the lime side hypoeutectic composition.
- H 2 0 is added, part of the Ca0 in the crystal mixture reacts according to the equation without the CaC 2 grown together with the CaO crystals being substantially attacked by the H 2 0.
- the grinding grains which consist of CaO-CaC 2 crystal growths in which part of the CaO crystals are hydrated, disintegrate at the prevailing temperatures above 800 ° C according to the following reaction equation
- the grinding grain Because of the gas development at the reactive crystal interfaces, the grinding grain literally bursts with the release of lime, which is highly reactive in statu nascendi, and with enlargement of the CaO-CaC 2 crystal surfaces grown together in the grain. With an almost eutectic crystal structure, there is an ideally large reaction surface.
- the reducing gases released offer ideal conditions for the implementation of Ca0 with the sulfur dissolved in the molten metal.
- Such a desulfurization mixture is particularly suitable for desulfurization processes in which the time for the conversion of the desulfurization mixture with the sulfur is very short.
- This process includes the immersion lance process, in which the desulfurization mixture should be converted as completely as possible by blowing desulfurization mixtures into a metal melt below its surface in the short time from the exit of the desulfurization mixture into the melt until it rises to the bath surface.
- the desulfurization mixture according to the invention is superior to the best known carbide-based mixtures in the desulfurization effect. Because of the intergranular gas reaction in the grinding grain, the conversion of CaC 2 to Ca0 and the resulting enlargement of the crystal surfaces is more effective, the gas development is much the same more moderate and less violent than with known desulfurization mixtures, for example according to DE-AS 22 52 795, to which gas-releasing additives are mechanically mixed. Desulphurization therefore takes place more quietly and with less metal emissions, particularly in the open pan and the torpedo pan.
- the material can be used in a coarser manner, so that expensive fine grinding can be dispensed with.
- the use of the desulfurization mixture according to the invention enables greater accuracy with regard to the final content required in each case.
- the production costs for the mixture according to the invention are considerably lower than for known agents based on carbide.
- a process for producing the mixture according to the invention is proposed, which is characterized in that finely divided calcium oxide is introduced in an excess of 3 to 15% by weight in a calcium carbide melt produced in the customary manner, which already has a calcium oxide content of up to 45% by weight.
- the calcium oxide which is introduced into the melt, is preheated to temperatures up to 2000 ° C., preferably up to 1100 ° C., and is introduced hot into the melt at these temperatures, it is possible to determine the CaO content in the carbide to increase to 80% by weight, the preheating being chosen the higher, the higher the desired proportion of additionally dissolved calcium oxide should be between 40 and 80% by weight. This enables use in low-carbon pig iron and steel melts and also increases the desulfurization yield, based on calcium carbide.
- the portions smaller than 4 mm which have been screened off after the preliminary crushing essentially consist of Ca0 and can be returned to the process as finely divided calcium oxide, where they together with fresh Ca0 as the starting pro duct serve. It was not foreseeable for the person skilled in the art that, by sieving off the fractions smaller than 4 mm after the preliminary breaking, those fractions which have no or only a slight desulfurization effect are removed from the product, and the effectiveness of the end product is thus considerably increased.
- the product produced according to the invention can be ground much better than products obtained by known processes. This is particularly important because in some cases the product has to be used with a grain size of less than 0.1 mm.
- Calcium carbide for example electrothermally, is produced in a known manner from lime and coke, the lime-coke mixture in the Möller being adjusted to a weight ratio of 100:40, which corresponds to a carbide with a CaO content of approximately 40% by weight.
- Ca0 with a grain size of 3 to 8 mm and a Ca (OH) 2 - and CaC0 3 content of less than 1% by weight each is injected into the jet of the molten carbide which has been tapped from the furnace into a crucible at such a rate and in such a rate Amounts entered that, until the crucible is filled, there is a total CaC 2 : CaO weight ratio of 43:57, which is an excess of 14% by weight CaO, based on the CaO content of 50 desired in the CaC 2 -CaO crystal mixture % By weight.
- the mixture is then cooled until the average temperature of the solidified carbide block is approximately 400 ° C., and the block is pre-crushed to sizes smaller than 150 mm.
- the fractions smaller than 4 mm obtained during the preliminary crushing essentially contain the CaO used in excess, while the remaining product with grain sizes larger than 4 mm represents a crystal mixture of 50% by weight CaC 2 and 50% by weight Ca0.
- 850 kg of this CaC 2 -CaO crystal mixture are mixed with 100 kg of limestone (grain size less than 1 mm) and 50 kg of coke breeze (grain size less than 3 mm) and by passing 1500 m 3 / h of air with a moisture content of 10 g / m 3 (at 15 ° C) in a rotary mill with a throughput of 500 kg / h at 50 ° C to grain sizes smaller than 0.1 mm.
- the screened grain fraction smaller than 4 mm is used together with fresh lime (Ca0) as the starting product.
- the product obtained contains 2% by weight of chemically bound water.
- Example 2 The procedure is as in Example 1, with the changes that the Ca0 is preheated to a temperature of about 1100 ° C. and the amount of Ca0 is increased so that a total Ca0 content of 62.5 wt % results, which corresponds to an excess of 4% by weight, based on the desired content of 60% by weight CaO in the finished end product.
- 1800 kg of the product worked up and ground according to the invention are used to desulfurize a 300 t steel melt with a sulfur content of 0.02% by weight at 1650 ° C.
- the sulfur content of the melt is reduced to less than 0.005% by weight.
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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)
- Treatment Of Steel In Its Molten State (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Abstract
Description
Die Erfindung betrifft ein Gemisch zum Entschwefeln von Metallschmelzen, insbesondere von Stahl- und Roheisenschmelzen, auf der Basis von im Schmelzfluß gewonnenen CaC2-CaO-Kristallgemengen sowie ein Verfahren zur Herstellung des Gemisches.The invention relates to a mixture for desulfurizing metal melts, in particular steel and pig iron melts, on the basis of CaC 2 -CaO crystal mixtures obtained in the melt flow, and to a method for producing the mixture.
Die DE-OS 29 07 069 beschreibt bereits ein Mittel zur Entschwefelung von Metallschmelzen, insbesondere von Roheisen und Stahl, auf der Basis CaC2/CaO, welches aus einem im Schmelzfluß hergestellten und anschließend zerkleinerten CaC2/CaO-Kristallgemenge mit einem CaC2-Anteil von 35 bis 65 Gew%, bezogen auf die CaC2/CaO-Menge, besteht. Es ist weiterhin Stand der Technik, Metallschmelzen mit technischem Carbid (ca. 80 Gew% CaC2, Rest Ca0) oder auch mit Mischungen von technischem Carbid mit Zusätzen an Kohlenstoff und gasabspaltenden Stoffen, z.B. Ca(OH)2, zu entschwefeln (DE-AS 22 52 795). Um einen guten Ausnutzungsgrad zu bekommen, hat man die bekannten Entschwefelungsgemische, insbesondere für den Einsatz nach dem Tauchlanzenverfahren, zunächst möglichst feinkörnig mahlen müssen. Danach entsprechen diese Gemische zwar den gestellten Anforderungen, sind jedoch sowohl bezüglich Herstellung als auch Eomsatz teuer. Trotz der Feinmahlung mußten zur Erzielung des gewünschten Entschwefelungsgrades verhältnismäßig große Mengen der Entschwefelungsgemische zugesetzt werden.DE-OS 29 07 069 already describes an agent for the desulfurization of molten metals, in particular pig iron and steel, based on CaC 2 / CaO, which consists of a CaC 2 / CaO crystal mixture produced in the melt flow and subsequently comminuted with a CaC 2 - Share of 35 to 65 wt%, based on the amount of CaC 2 / CaO, exists. It is also state of the art to desulfurize metal melts with technical carbide (approx. 80% by weight CaC 2 , remainder Ca0) or also with mixtures of technical carbide with additions of carbon and gas-releasing substances, eg Ca (OH) 2 (DE- AS 22 52 795). In order to get a good degree of utilization, the known desulfurization mixtures, especially for use by the immersion lance method, first had to be ground as finely as possible. According to this, these mixtures meet the requirements, but are expensive both in terms of manufacture and in terms of electrical energy consumption. Despite the fine grinding, relatively large amounts of the desulfurization mixtures had to be added in order to achieve the desired degree of desulfurization.
Aufgabe der vorliegenden Erfindung ist es daher, ein Entschwefelungsgemisch zu schaffen, das einen besseren Ausnutzungsgrad bietet, und ein wirtschaftliches Verfahren zur Herstellung dieses Gemisches bereitzustellen.The object of the present invention is therefore to create a desulfurization mixture which offers a better degree of utilization and to provide an economical process for the production of this mixture.
Es wird daher erfindungsgemäß vorgeschlagen, daß die Gemische freien Kohlenstoff und Carbonat enthalten und im CaC2-CaO-Kristallgemenge ein Teil des CaO zu Ca(OH)2 hydratisiert ist. Hierbei geht man vorzugsweise von CaC2-CaO-Kristallgemengen mit einem Anteil von 40 bis 80 Gew% Ca0 (entsprechend 20 bis 60 Gew% CaC2), insbesondere 45 bis 80 Gew% Ca0 (entsprechend 20 bis 55 Gew% CaC2) oder 40 bis 65 Gew% Ca0 (entsprechend 35 bis 60 Gew% CaC2) aus. Das erfindungsgemäße Gemisch ist weiterhin bevorzugt dadurch gekennzeichnet, daß es 1 bis 6 Gew%, vorzugsweise 2,5 bis 3,5 Gew%, von an Calciumoxid chemisch gebundenem Wasser enthält. Die Gemische der Erfindung enthalten neben dem im Schmelzfluß gewonnenen CaC2-CaO-Kristallgemenge bevorzugt 0,5 bis 8 Gew% freien Kohlenstoff (z.B. Koksgrus, Anthrazit, Graphit, Ruß) und 0,5 bis 20 Gew% Carbonate des Calciums, Magnesiums oder Natriums.It is therefore proposed according to the invention that the mixtures contain free carbon and carbonate and that part of the CaO 2 -CaO crystal mixture is hydrated to Ca (OH) 2 . CaC 2 -CaO crystal mixtures with a proportion of 40 to 80% by weight Ca0 (corresponding to 20 to 60% by weight CaC 2 ), in particular 45 to 80% by weight Ca0 (corresponding to 20 to 55% by weight CaC 2 ) or 40 to 65 wt% Ca0 (corresponding to 35 to 60 wt% CaC 2 ). The mixture according to the invention is furthermore preferably characterized in that it contains 1 to 6% by weight, preferably 2.5 to 3.5% by weight, of water chemically bound to calcium oxide. In addition to the CaC 2 -CaO crystal mixture obtained in the melt flow, the mixtures of the invention preferably contain 0.5 to 8% by weight of free carbon (for example coke breeze, anthracite, graphite, carbon black) and 0.5 to 20% by weight of carbonates of calcium, magnesium or Sodium.
Beim Erstarren aus dem Schmelzfluß kristallisieren Ca0 und CaC2 als Kristallgemenge, in dem die CaC2- und CaO-Kristalle ineinander verwachsen vorliegen, und zwar bei dem angegebenen CaC2/CaO-Mengenverhältnis mit einer im Bereich des Eutektikums liegenden bzw. zur Kalkseite verschobenen untereutektischen Zusammensetzung. Beim Zusatz von H20 reagiert ein Teil des Ca0 im Kristallgemenge nach der Gleichung
Wenn ein solches Entschwefelungsgemisch in eine Metallschmelze eingeblasen wird, so zerfallen die Mahlkörner, die aus CaO-CaC2-Kristallverwachsungen bestehen, in denen ein Teil der CaO-Kristalle hydratisiert ist, bei den herrschenden Temperaturen oberhalb 800°C nach folgender Reaktionsgleichung
Wegen der Gasentwicklung an den reaktiven Kristallgrenzflächen zerplatzt das Mahlkorn regelrecht unter Freisetzung von in statu nascendi hochreaktivem Kalk und unter Vergrößerung der im Korn verwachsenen CaO-CaC2-Kristalloberflächen. Bei nahezu eutektischem Kristallaufbau ergibt sich eine ideal große Reaktionsoberfläche. Die freiwerdenden reduzierend wirkenden Gase bieten.dabei ideale Voraussetzungen für eine Umsetzung des Ca0 mit dem in der Metallschmelze gelösten Schwefel.Because of the gas development at the reactive crystal interfaces, the grinding grain literally bursts with the release of lime, which is highly reactive in statu nascendi, and with enlargement of the CaO-CaC 2 crystal surfaces grown together in the grain. With an almost eutectic crystal structure, there is an ideally large reaction surface. The reducing gases released offer ideal conditions for the implementation of Ca0 with the sulfur dissolved in the molten metal.
Ein solches Entschwefelungsgemisch eignet sich insbesondere hervorragend bei Entschwefelungsprozessen, bei denen die Zeit für den Umsatz des Entschwefelungsgemischs mit dem Schwefel sehr kurz ist. Zu diesem Verfahren gehört das Tauchlanzenverfahren, bei dem durch Einblasen von Entschwefelungsgemischen in eine Metallschmelze unterhalb deren Oberfläche in der kurzen Zeit vom Austritt des Entschwefelungsgemisches in die Schmelze bis zum Aufsteigen an die Badoberfläche die Umsetzung des Entschwefelungsgemisches möglichst vollständig erfolgen sollte.Such a desulfurization mixture is particularly suitable for desulfurization processes in which the time for the conversion of the desulfurization mixture with the sulfur is very short. This process includes the immersion lance process, in which the desulfurization mixture should be converted as completely as possible by blowing desulfurization mixtures into a metal melt below its surface in the short time from the exit of the desulfurization mixture into the melt until it rises to the bath surface.
Das erfindungsgemäße Entschwefelungsgemisch zeigt sich den besten bekannten Gemischen auf Carbidbasis in der Entschwefelungswirkung überlegen. Wegen der interkristallinen Gasreaktion im Mahlkorn ist die Umsetzung von CaC2 zu Ca0 und die dadurch bedingte Vergrößerung der Kristalloberflächen wirkungsvoller, die Gasentwicklung viel gleichmäßiger und weniger heftig als bei bekannten Entschwefelungsgemischen, z.B. gemäß DE-AS 22 52 795, denen gasabspaltende Zusätze mechanisch untergemengt sind. Die Entschwefelung erfolgt deshalb insbesondere in der offenen Pfanne und der Torpedopfanne ruhiger und mit geringeren Metallauswürfen. Wegen der höheren Reaktivität des erfindungsgemäßen Entschwefelungsgemisches als Folge der Vergrößerung der Kristalloberflächen beim Zerplatzen des Mahlkorns in der Schmelze kann das Material grobkörniger eingesetzt werden, so daß teures Feinmahlen entfallen kann.The desulfurization mixture according to the invention is superior to the best known carbide-based mixtures in the desulfurization effect. Because of the intergranular gas reaction in the grinding grain, the conversion of CaC 2 to Ca0 and the resulting enlargement of the crystal surfaces is more effective, the gas development is much the same more moderate and less violent than with known desulfurization mixtures, for example according to DE-AS 22 52 795, to which gas-releasing additives are mechanically mixed. Desulphurization therefore takes place more quietly and with less metal emissions, particularly in the open pan and the torpedo pan. Because of the higher reactivity of the desulfurization mixture according to the invention as a result of the enlargement of the crystal surfaces when the grinding grain bursts in the melt, the material can be used in a coarser manner, so that expensive fine grinding can be dispensed with.
Die Verwendung des erfindungsgemäßen Entschwefelungsgemisches ermöglicht wegen seiner homogenen Zusammensetzung eine größere Treffsicherheit auf den jeweils geforderten Endgehalt. Die Herstellungskosten für das erfindungsgemäße Gemisch liegen erheblich niedriger als für bekannte Mittel auf Carbidbasis.Due to its homogeneous composition, the use of the desulfurization mixture according to the invention enables greater accuracy with regard to the final content required in each case. The production costs for the mixture according to the invention are considerably lower than for known agents based on carbide.
Weiterhin wird ein Verfahren zur Herstellung des erfindungsgemäßen Gemisches vorgeschlagen, welches dadurch gekennzeichnet ist, daß man in eine in üblicher Weise erzeugte Calciumcarbidschmelze, welche bereits einen Calciumoxidgehalt bis zu 45 Gew% aufweist, feinteiliges Calciumoxid einträgt, in einem Überschuß von 3 bis 15 Gew%, bezogen auf die im CaC2-CaO-Kristallgemenge gewünschte Menge, dann die erhaltene Mischung unter Erstarren auf Temperaturen von 350 bis 450°C abkühlt, bei diesen Temperaturen auf Korngrößen kleiner als 150 mm vorbricht, den dabei zwangsläufig anfallenden Kornanteil kleiner als 4 mm vom verbleibenden Produkt abtrennt, letzterem freien Kohlenstoff und Carbonat zumischt und das Gemisch in Gegenwart von Luft oder Stickstoff mit einem Feuchtigkeitsgehalt von 5 bis 20 g/m3 (bei 1,013 bar und 273,15 K) durch Brechen und Mahlen bei Temperaturen unterhalb 100°C, vorzugsweise von 10 - 50°C, auf Korngrößen kleiner als 10 mm, vorzugsweise kleiner als 0,1 mm, zerkleinert.Furthermore, a process for producing the mixture according to the invention is proposed, which is characterized in that finely divided calcium oxide is introduced in an excess of 3 to 15% by weight in a calcium carbide melt produced in the customary manner, which already has a calcium oxide content of up to 45% by weight. , based on the amount desired in the CaC 2 -CaO crystal mixture, then cools the resulting mixture under solidification to temperatures of 350 to 450 ° C, at these temperatures breaks down to grain sizes less than 150 mm, the grain fraction inevitably obtained is less than 4 mm separated from the remaining product, the latter mixed free carbon and carbonate and the mixture in the presence of air or nitrogen with a moisture content of 5 to 20 g / m 3 (at 1.013 bar and 273.15 K) by breaking and grinding at temperatures below 100 ° C, preferably from 10-50 ° C, crushed to grain sizes smaller than 10 mm, preferably smaller than 0.1 mm.
Wahlweise und bevorzugt ist dieses Herstellungsverfahren dadurch gekennzeichnet, daß
- a) die Zugabe des Calciumoxids, die sogenannte Magerung des Carbids, unter Ausnutzung des Wärneinhaltes des Carbids in einem Tiegel durchgeführt wird,
- b) man das Calciumoxid, welches in die Calciumcarbidschmelze eingetragen wird, auf Temperaturen bis zu 20000C vorerhitzt und heiß in die Schmelze einbringt, wobei die Vorerhitzung um so höher gewählt wird, je höher der gewünschte Anteil an zusätzlich gelöstem Calciumoxid zwischen 40 und 80 Gew% liegen soll,
- c) von einer Calciumcarbidschmelze ausgegangen wird, welche zwischen 20 und 45 Gew% Calciumoxid enthält,
- d) man die nach dem Vorbrechen abgesiebten Anteile kleiner als 4 mm in den Prozeß zurückführt.
- a) the addition of the calcium oxide, the so-called thinning of the carbide, is carried out using the heat content of the carbide in a crucible,
- b) contacting the calcium oxide which is added to the Calciumcarbidschmelze, up to 2000 0 C preheated to temperatures and hot in the melt is introduced, wherein the preheating is selected to be higher, the higher the desired proportion of additionally dissolved calcium oxide between 40 and 80 % By weight should be
- c) a calcium carbide melt is assumed which contains between 20 and 45% by weight calcium oxide,
- d) the portions smaller than 4 mm which have been screened off after preliminary crushing are returned to the process.
Wenn das Calciumoxid, welches in die Schmelze eingetragen wird, vorher auf Temperaturen bis zu 2000°C, vorzugsweise bis zu 1100°C, vorerhitzt und mit diesen Temperaturen heiß in die Schmelze eingebracht wird, so ist es möglich, den Ca0-Gehalt im Carbid bis auf 80 Gew% zu erhöhen, wobei die Vorerhitzung um so höher gewählt wird, je höher der gewünschte Anteil an zusätzlich gelöstem Calciumoxid zwischen 40 und 80 Gew% liegen soll. Dadurch wird die Anwendung in kohlenstoffarmen Roheisen- und Stahlschmelzen ermöglicht und außerdem die Entschwefelungsausbeute, bezogen auf Calciumcarbid, erhöht.If the calcium oxide, which is introduced into the melt, is preheated to temperatures up to 2000 ° C., preferably up to 1100 ° C., and is introduced hot into the melt at these temperatures, it is possible to determine the CaO content in the carbide to increase to 80% by weight, the preheating being chosen the higher, the higher the desired proportion of additionally dissolved calcium oxide should be between 40 and 80% by weight. This enables use in low-carbon pig iron and steel melts and also increases the desulfurization yield, based on calcium carbide.
Die nach dem Vorbrechen abgesiebten Anteile kleiner als 4 mm bestehen im wesentlichen aus Ca0 und können als feinteiliges Calciumoxid wieder in den Prozeß zurückgeführt werden, wo sie zusammen mit frischem Ca0 als Ausgangsprodukt dienen. Nicht vorhersehbar war für den Fachmann, daß durch das Absieben der nach dem Vorbrechen abfallenden Anteile kleiner als 4 mm aus dem Produkt die Anteile entfernt werden, welche keine oder nur eine geringe Entschwefelungswirkung besitzen, und so die Wirksamkeit des Endproduktes erheblich gesteigert wird.The portions smaller than 4 mm which have been screened off after the preliminary crushing essentially consist of Ca0 and can be returned to the process as finely divided calcium oxide, where they together with fresh Ca0 as the starting pro duct serve. It was not foreseeable for the person skilled in the art that, by sieving off the fractions smaller than 4 mm after the preliminary breaking, those fractions which have no or only a slight desulfurization effect are removed from the product, and the effectiveness of the end product is thus considerably increased.
Das erfindungsgemäß hergestellte Produkt läßt sich wesentlich besser mahlen als nach bekannten Verfahren erhaltene Produkte. Dies ist deshalb von besonderer Wichtigkeit, weil das Produkt in manchen Fällen mit einer Körnung kleiner als 0,1 mm eingesetzt werden muß.The product produced according to the invention can be ground much better than products obtained by known processes. This is particularly important because in some cases the product has to be used with a grain size of less than 0.1 mm.
Anhand der folgenden Beispiele wird die Erfindung näher erläutert:The invention is explained in more detail using the following examples:
In bekannter Weise wird aus Kalk und Koks Calciumcarbid, z.B. elektrothermisch, hergestellt, wobei die Kalk-Koks-Mischung im Möller auf ein Gewichtsverhältnis von 100 : 40 eingestellt wird, was einem Carbid mit einem Ca0-Gehalt von ca. 40 Gew% entspricht. In den Strahl des aus dem Ofen in einen Tiegel abgestochenen schmelzflüssigen Carbides wird Ca0 mit einer Körnung von 3 bis 8 mm und einem Ca(OH)2- und CaC03-Gehalt von jeweils weniger als 1 Gew% mit einer solchen Geschwindigkeit und in solchen Mengen eingetragen, daß, bis der Tiegel gefüllt ist, insgesamt ein CaC2 : CaO-Gewichtsverhältnis von 43 : 57 vorliegt, was einem Überschuß von 14 Gew% CaO, bezogen auf den im CaC2-CaO-Kristallgemenge gewünschten Ca0-Gehalt von 50 Gew%, entspricht. Dann wird abgekühlt, bis die Durchschnittstemperatur des dabei erstarrten Carbidblokkes etwa 400°C beträgt, und der Block auf Größen kleiner als 150 mm vorgebrochen.Calcium carbide, for example electrothermally, is produced in a known manner from lime and coke, the lime-coke mixture in the Möller being adjusted to a weight ratio of 100:40, which corresponds to a carbide with a CaO content of approximately 40% by weight. Ca0 with a grain size of 3 to 8 mm and a Ca (OH) 2 - and CaC0 3 content of less than 1% by weight each is injected into the jet of the molten carbide which has been tapped from the furnace into a crucible at such a rate and in such a rate Amounts entered that, until the crucible is filled, there is a total CaC 2 : CaO weight ratio of 43:57, which is an excess of 14% by weight CaO, based on the CaO content of 50 desired in the CaC 2 -CaO crystal mixture % By weight. The mixture is then cooled until the average temperature of the solidified carbide block is approximately 400 ° C., and the block is pre-crushed to sizes smaller than 150 mm.
Die beim Vorbrechen anfallenden Anteile kleiner als 4 mm enthalten im wesentlichen das im Überschuß eingesetzte CaO, während das zurückbleibende Produkt mit Korngrößen größer als 4 mm ein Kristallgemenge von 50 Gew% CaC2 und 50 Gew% Ca0 darstellt. 850 kg dieses CaC2-CaO-Kristallgemenges werden mit 100 kg Kalkstein (Körnung kleiner 1 mm) und 50 kg Koksgrus (Körnung kleiner 3 mm) vermischt und unter Durchleiten von 1500 m3/h Luft mit einem Feuchtigkeitsgehalt von 10 g/m3 (bei 15°C) in einer Rotationsmühle mit einem Durchsatz von 500 kg/h bei 50°C auf Korngrößen kleiner als 0,1 mm gemahlen. Die abgesiebte Kornfraktion kleiner als 4 mm wird zusammen mit frischem Kalk (Ca0) wieder als Ausgangsprodukt eingesetzt. Das erhaltene Produkt enthält 2 Gew% chemisch gebundenes Wasser.The fractions smaller than 4 mm obtained during the preliminary crushing essentially contain the CaO used in excess, while the remaining product with grain sizes larger than 4 mm represents a crystal mixture of 50% by weight CaC 2 and 50% by weight Ca0. 850 kg of this CaC 2 -CaO crystal mixture are mixed with 100 kg of limestone (grain size less than 1 mm) and 50 kg of coke breeze (grain size less than 3 mm) and by passing 1500 m 3 / h of air with a moisture content of 10 g / m 3 (at 15 ° C) in a rotary mill with a throughput of 500 kg / h at 50 ° C to grain sizes smaller than 0.1 mm. The screened grain fraction smaller than 4 mm is used together with fresh lime (Ca0) as the starting product. The product obtained contains 2% by weight of chemically bound water.
Durch Einblasen von 1500 kg dieses Produktes in eine 300 t-Roheisenschmelze mit einem Schwefelgehalt von 0,03 Gew% bei Temperaturen von 1400°C wird der Schwefelgehalt der Eisenschmelze auf weniger als 0,005 Gew% gesenkt.By blowing 1500 kg of this product into a 300 t pig iron melt with a sulfur content of 0.03% by weight at temperatures of 1400 ° C, the sulfur content of the iron melt is reduced to less than 0.005% by weight.
Es wird wie im Beispiel 1 verfahren, mit den Änderungen, daß das Ca0 vor dem Eintragen auf eine Temperatur von etwa 1100°C vorerhitzt und die Menge an Ca0 so erhöht wird, daß sich insgesamt im Tiegel ein Ca0-Gehalt von 62,5 Gew% ergibt, was einem Überschuß von 4 Gew% entspricht, bezogen auf den im fertigen Endprodukt gewünschten Gehalt von 60 Gew% CaO.The procedure is as in Example 1, with the changes that the Ca0 is preheated to a temperature of about 1100 ° C. and the amount of Ca0 is increased so that a total Ca0 content of 62.5 wt % results, which corresponds to an excess of 4% by weight, based on the desired content of 60% by weight CaO in the finished end product.
1800 kg des erfindungsgemäß aufgearbeiteten und gemahlenen Produktes werden zur Entschwefelung einer 300 t-Stahlschmelze mit einem Schwefelgehalt von 0,02 Gew% bei 1650°C eingesetzt. Dabei wird der Schwefelgehalt der Schmelze auf weniger als 0,005 Gew% gesenkt.1800 kg of the product worked up and ground according to the invention are used to desulfurize a 300 t steel melt with a sulfur content of 0.02% by weight at 1650 ° C. The sulfur content of the melt is reduced to less than 0.005% by weight.
a) Eine 300 t-Roheisenschmelze mit folgender Analyse (Gew%):
- 4,5 % Kohlenstoff, 0,8 % Silizium, 0,7 % Mangan, 0,08 % Phosphor, 0,064 % Schwefel, Rest Eisen wurde nach dem Tauchlanzenverfahren mit dem erfindungsgemäßen Entschwefelungsgemisch aus Beispiel 1 in einer offenen Pfanne entschwefelt. Die Tauchtiefe der Lanze betrug 1,8 m. Die Einblasgeschwindigkeit betrug 100 kg/min. Der Gesamtverbrauch des Entschwefelungsgemisches betrug 4,5 kg/t, mit dem der Schwefelgehalt auf 0,009 Gew% gesenkt wurde. Das entspricht einem Entschwefelungsgrad von 86 %.
- 4.5% carbon, 0.8% silicon, 0.7% manganese, 0.08% phosphorus, 0.064% sulfur, the remainder iron was desulphurized in an open pan by the immersion lance method with the desulfurization mixture according to the invention from Example 1. The depth of the lance was 1.8 m. The blowing speed was 100 kg / min. The total consumption of the desulfurization mixture was 4.5 kg / t, with which the sulfur content was reduced to 0.009% by weight. This corresponds to a degree of desulfurization of 86%.
b) Bei einem Vergleichsversuch mit einem zum Stand der Technik gehörenden Gemisch, bestehend aus 85 Gew% technischem Carbid (78 Gew% CaC2-Gehalt) und 15 Gew% CaC03 benötigte man mit der gleichen Tauchtiefe und Einblasgeschwindigkeit wie unter 3 a) 6,0 kg/t, um bei gleichem Schwefelausgangsgehalt denselben Entschwefelungsgrad zu erreichen.b) In a comparative test with a mixture belonging to the prior art, consisting of 85% by weight technical carbide (78% by weight CaC 2 content) and 15% by weight CaC0 3 , the same immersion depth and blowing rate as under 3 a) 6 were required .0 kg / t in order to achieve the same desulfurization level with the same initial sulfur content.
Bei dem erfindungsgemäßen Entschwefelungsgemisch ergibt sich gegenüber dem bei diesem Vergleichsversuch benutzten bekannten Entschwefelungsgemisch eine Ersparnis von 25 %, bezogen auf die absolute Menge an Entschwefelungsgemisch, und eine Ersparnis von 45 %, bezogen auf den CaC2-Anteil. Im selben Maß verkürzt sich auch die Behandlungszeit.In the desulfurization mixture according to the invention, compared to the known desulfurization mixture used in this comparative test, there is a saving of 25%, based on the absolute amount of desulfurization mixture, and a saving of 45%, based on the CaC 2 content. The treatment time is shortened to the same extent.
Claims (8)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT82101428T ATE9232T1 (en) | 1981-03-24 | 1982-02-25 | PROCESS FOR THE MANUFACTURE OF A DESULPHURIZING AGENT FOR MELTED PIG IRON AND STEEL. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19813111510 DE3111510A1 (en) | 1981-03-24 | 1981-03-24 | DESULFURATION MIXTURE AND METHOD FOR THE PRODUCTION THEREOF |
DE3111510 | 1981-03-24 |
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EP0061012A1 true EP0061012A1 (en) | 1982-09-29 |
EP0061012B1 EP0061012B1 (en) | 1984-09-05 |
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EP82101428A Expired EP0061012B1 (en) | 1981-03-24 | 1982-02-25 | Process for producing desulfurizing agents for pig iron and steel melts |
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US (1) | US4395282A (en) |
EP (1) | EP0061012B1 (en) |
JP (1) | JPS57171611A (en) |
AT (1) | ATE9232T1 (en) |
BR (1) | BR8201621A (en) |
CA (1) | CA1184385A (en) |
DD (1) | DD202182A5 (en) |
DE (2) | DE3111510A1 (en) |
ES (1) | ES510768A0 (en) |
ZA (1) | ZA821940B (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2160896A (en) * | 1984-06-27 | 1986-01-02 | Boc Group Inc | Agents for the removal of impurities from a molten metal and a process for producing same |
Families Citing this family (13)
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CA1240842A (en) * | 1984-05-16 | 1988-08-23 | Heinrich Rellermeyer | Method, process and composition for desulfurizing pig-iron melts |
BR8606249A (en) * | 1985-12-17 | 1987-09-29 | Sueddeutsche Kalkstickstoff | FINALLY GRANULATED COMPOSITION FOR THE DESULFURATION OF CAST IRON AND PROCESS FOR ITS PREPARATION |
DE3908071A1 (en) * | 1989-03-13 | 1990-09-20 | Hoechst Ag | MEANS AND METHOD FOR DISCHARGING METAL MELTS |
US5358550A (en) * | 1992-10-26 | 1994-10-25 | Rossborough Manufacturing Company | Desulfurization agent |
US5407459A (en) * | 1993-09-23 | 1995-04-18 | Alcan International Limited | Process for the preparation of calcium aluminates from aluminum dross residues |
AT406690B (en) * | 1994-12-09 | 2000-07-25 | Donau Chemie Ag | AGENT FOR TREATING RAW IRON AND CAST IRON MELT FOR THE PURPOSE OF DESULFURATION |
US6238633B1 (en) | 1997-06-30 | 2001-05-29 | Aluminum Waste Technology, Inc. | Process for preparing calcium aluminate from aluminum dross |
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 |
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 |
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CH428820A (en) * | 1963-12-12 | 1967-01-31 | Tech Entwicklung Und Verwertun | Steel refining product |
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DE1758250B1 (en) * | 1968-04-29 | 1971-10-28 | Sueddeutsche Kalkstickstoff | Agent for the desulphurisation of iron melts |
-
1981
- 1981-03-24 DE DE19813111510 patent/DE3111510A1/en not_active Withdrawn
-
1982
- 1982-02-25 AT AT82101428T patent/ATE9232T1/en not_active IP Right Cessation
- 1982-02-25 DE DE8282101428T patent/DE3260643D1/en not_active Expired
- 1982-02-25 EP EP82101428A patent/EP0061012B1/en not_active Expired
- 1982-03-16 CA CA000398496A patent/CA1184385A/en not_active Expired
- 1982-03-18 US US06/359,228 patent/US4395282A/en not_active Expired - Fee Related
- 1982-03-19 DD DD82238306A patent/DD202182A5/en unknown
- 1982-03-23 ZA ZA821940A patent/ZA821940B/en unknown
- 1982-03-23 BR BR8201621A patent/BR8201621A/en unknown
- 1982-03-24 JP JP57045747A patent/JPS57171611A/en active Granted
- 1982-03-24 ES ES510768A patent/ES510768A0/en active Granted
Patent Citations (8)
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DE2252795B2 (en) * | 1972-10-27 | 1977-02-03 | Süddeutsche Kalkstickstoff-Werke AG, 8223 Trostberg | DESULFURIZING AGENT FOR METAL MELTING WITH WATER-RELEASING ADDITIVE |
DE2326539A1 (en) * | 1973-05-24 | 1974-12-12 | Sueddeutsche Kalkstickstoff | PROCESS FOR THE PREPARATION OF HYDROGEN MIXTURES BASED ON CALCIUM CARBIDE FOR DESULFURIZING METAL MELT |
DE2741588A1 (en) * | 1977-09-15 | 1979-03-29 | Sueddeutsche Kalkstickstoff | AGENT FOR DESULFURIZING FELT IRON |
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EP0019086A2 (en) * | 1979-05-19 | 1980-11-26 | Hoechst Aktiengesellschaft | Process for producing desulfurizing agents for pig iron or steel melts |
EP0031534A1 (en) * | 1979-12-29 | 1981-07-08 | Hoechst Aktiengesellschaft | Process for producing desulfurizing agents for pig iron or steel melts |
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GB2160896A (en) * | 1984-06-27 | 1986-01-02 | Boc Group Inc | Agents for the removal of impurities from a molten metal and a process for producing same |
Also Published As
Publication number | Publication date |
---|---|
ES8302103A1 (en) | 1983-02-01 |
DD202182A5 (en) | 1983-08-31 |
JPH0152446B2 (en) | 1989-11-08 |
US4395282A (en) | 1983-07-26 |
CA1184385A (en) | 1985-03-26 |
DE3260643D1 (en) | 1984-10-11 |
BR8201621A (en) | 1983-02-16 |
ATE9232T1 (en) | 1984-09-15 |
ZA821940B (en) | 1983-02-23 |
JPS57171611A (en) | 1982-10-22 |
ES510768A0 (en) | 1983-02-01 |
DE3111510A1 (en) | 1982-10-07 |
EP0061012B1 (en) | 1984-09-05 |
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