EP0031552A1 - Desulphurising composition and process for its production - Google Patents
Desulphurising composition and process for its production Download PDFInfo
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- EP0031552A1 EP0031552A1 EP80108013A EP80108013A EP0031552A1 EP 0031552 A1 EP0031552 A1 EP 0031552A1 EP 80108013 A EP80108013 A EP 80108013A EP 80108013 A EP80108013 A EP 80108013A EP 0031552 A1 EP0031552 A1 EP 0031552A1
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- EP
- European Patent Office
- Prior art keywords
- weight
- calcium oxide
- cao
- melt
- temperatures
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- 239000000203 mixture Substances 0.000 title claims abstract description 30
- 238000000034 method Methods 0.000 title claims description 24
- 238000004519 manufacturing process Methods 0.000 title abstract description 7
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 33
- 239000013078 crystal Substances 0.000 claims abstract description 26
- 239000000155 melt Substances 0.000 claims abstract description 17
- 229910052751 metal Inorganic materials 0.000 claims abstract description 8
- 239000002184 metal Substances 0.000 claims abstract description 8
- 230000003009 desulfurizing effect Effects 0.000 claims abstract description 7
- 229910000805 Pig iron Inorganic materials 0.000 claims abstract description 6
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 3
- 239000010959 steel Substances 0.000 claims abstract description 3
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 75
- 239000000292 calcium oxide Substances 0.000 claims description 35
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims description 21
- 239000000047 product Substances 0.000 claims description 14
- 239000005997 Calcium carbide Substances 0.000 claims description 10
- CLZWAWBPWVRRGI-UHFFFAOYSA-N tert-butyl 2-[2-[2-[2-[bis[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]amino]-5-bromophenoxy]ethoxy]-4-methyl-n-[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]anilino]acetate Chemical compound CC1=CC=C(N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)C(OCCOC=2C(=CC=C(Br)C=2)N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)=C1 CLZWAWBPWVRRGI-UHFFFAOYSA-N 0.000 claims description 10
- 239000007795 chemical reaction product Substances 0.000 claims description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 238000002360 preparation method Methods 0.000 claims description 5
- 239000011575 calcium Substances 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 239000000463 material Substances 0.000 claims description 2
- 238000007711 solidification Methods 0.000 claims description 2
- 230000008023 solidification Effects 0.000 claims description 2
- 238000006477 desulfuration reaction Methods 0.000 description 20
- 230000023556 desulfurization Effects 0.000 description 20
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 9
- 229910052717 sulfur Inorganic materials 0.000 description 9
- 239000011593 sulfur Substances 0.000 description 9
- 239000007789 gas Substances 0.000 description 6
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 5
- 235000011941 Tilia x europaea Nutrition 0.000 description 5
- 239000004571 lime Substances 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 238000007664 blowing Methods 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000007654 immersion Methods 0.000 description 4
- 239000000571 coke Substances 0.000 description 3
- 239000000654 additive Substances 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000005496 eutectics Effects 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 239000000161 steel melt Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000010436 fluorite Substances 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000011236 particulate material Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 239000000256 polyoxyethylene sorbitan monolaurate Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/064—Dephosphorising; Desulfurising
- C21C7/0645—Agents used for dephosphorising or desulfurising
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/02—Dephosphorising or desulfurising
- C21C1/025—Agents used for dephosphorising or desulfurising
Definitions
- the invention relates to an agent for desulfurizing metal melts, in particular steel and pig iron melts, on the basis of CaC2-CaO crystal mixtures obtained in the melt flow, and to a method for producing the agent.
- Desulphurization agents based on CaC2-Ca0 and those which can additionally contain fluorspar are known (DE-PS 20 37 758). It is also state of the art to melt metal with technical carbide (approx. 80% by weight CaC 2 , rest Ca0) or also mixtures of such carbide with additives such as lime, coke, gas-releasing substances, e.g. CaCO 3 , CaCN 2 , Ca (OH ) To desulfurize 2 (DE-AS 22 52 795). In order to get a good degree of utilization, the known desulfurization agents, in particular for use by the immersion lance method, first had to be ground as finely as possible. According to this, these agents meet the requirements, but are expensive both in terms of manufacture and use. Despite the fine grinding, relatively large amounts of the desulfurizing agents had to be added to achieve the desired degree of desulfurization.
- part of the Ca0 in the crystal mixture is hydrated to Ca (OH) 2 .
- the agent according to the invention is furthermore preferably characterized in that Ca0 in the crystal mixture is hydrated with 1 to 6% by weight H 2 0, preferably 2.5 to 3.5% by weight H 2 0, based on the amount of CaC 2 -CaO.
- Ca0 and CaC 2 crystallize as a crystal mixture in which the CaC 2 and Ca0 crystals are intertwined, specifically at the CaC 2 / CaO quantitative ratio given, 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 adhesions in which some of the Ca0 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 in statu nascendi highly reactive lime and with enlargement of the overgrown CaO-CaC 2 crystal surfaces. With an almost eutectic crystal structure, there is an ideally large reaction surface.
- the released reducing gases offer ideal conditions for the implementation of Ca0 with the sulfur dissolved in the molten metal.
- Such a desulfurization agent is particularly suitable for desulfurization processes in which the time for the desulfurization agent to react with the sulfur is very short.
- This process includes the immersion lance process, in which the desulfurization agent should be converted as completely as possible by blowing desulfurization agents into a molten metal below its surface in the short time from the point at which the desulfurization agent emerges in the melt until it rises to the bath surface.
- the desulfurization agent according to the invention is superior to the best known carbide-based agents 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 are more effective, the gas development is much more uniform and less violent than with known desulfurization agents, 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 size, so that expensive fine grinding can be dispensed with.
- the use of the desulfurization agent according to the invention enables greater accuracy with regard to the final content required in each case.
- the production costs for the agent according to the invention are considerably lower than for known agents based on carbide.
- the process can be characterized in that, for the production of the end product, which contains 2o to 55% by weight calcium carbide, more than 45 to 8o% by weight calcium oxide and water chemically bound to calcium oxide, calcium carbide melt which is present and produced in a customary manner and which Already has a calcium oxide content of up to 45% by weight, finely divided calcium oxide is introduced in an excess of 3 to 15% by weight, based on the amount desired in the end product, then the mixture obtained cools to temperatures of 35 ° to 450 ° C.
- 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 higher the preheating chosen, the higher the desired proportion of additionally dissolved calcium oxide should be between 45 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 that have been screened off after the preliminary crushing essentially consist of Ca0 and can be recycled back into the process as finely divided calcium oxide, where they serve as the starting product together with fresh Ca0. It was not foreseeable for the person skilled in the art that the sieving of the An parts smaller than 4 mm are removed from the product, the parts that have no or only a low desulfurization effect, and so the effectiveness of the end product is significantly 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 : Ca0 weight ratio of 43:57, which corresponds to an excess of 14% by weight Ca0, based on the Ca0 content of 50% by weight desired in the end product. It is then cooled until the average temperature of the solidified carbide block is approximately 400 ° C., and the block is pre-broken 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 contains a crystal mixture of 50% by weight CaC 2 and 50% by weight Ca0 represents that then with passage of 1500 m 3 / h of air with a moisture content of 1o g / m 3 (at 15 ° C) in a rotary mill with a throughput of 5oo kg / h at 5o ° C to grain sizes less than 0.1 mm is ground.
- the screened grain fraction smaller than 4 mm is used together with fresh lime (Ca0) as the starting product.
- the product obtained contains 2.5% 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 Ca0 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)
- Lubricants (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
Die vorliegende Erfindung betrifft Mittel zum Entschwefeln von Metallschmelzen, insbesondere von Stahl- und Roheisenschmelzen, auf der Basis von im Schmelzfluss gewonnenen CaC2-CaO-Kristallgemengen, die sich dadurch auszeichnen, dass im Kristallgemenge ein Teil des CaO zu Ca(OH)2 hydratisiert ist. Ferner wird ein Verfahren zur Herstellung dieser Mittel beschrieben.The present invention relates to agents for desulfurizing metal melts, in particular steel and pig iron melts, on the basis of CaC2-CaO crystal mixtures obtained in the melt flow, which are characterized in that part of the CaO in the crystal mixture is hydrated to Ca (OH) 2 . A method for producing these agents is also described.
Description
Die Erfindung betrifft ein Mittel 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 Mittels.The invention relates to an agent for desulfurizing metal melts, in particular steel and pig iron melts, on the basis of CaC2-CaO crystal mixtures obtained in the melt flow, and to a method for producing the agent.
Entschwefelungsmittel auf der Basis CaC2-Ca0 und solche, die zusätzlich noch Flußspat enthalten können, sind bekannt (DE-PS 20 37 758). Es ist weiterhin Stand der Technik, Metallschmelzen mit technischem Carbid (ca. 80 Gew% CaC2, Rest Ca0) oder auch Mischungen von solchem Carbid mit Zusätzen, wie Kalk, Koks, gasabspaltenden Stoffen, z.B. CaCO3, CaCN2, Ca(OH)2 zu entschwefeln (DE-AS 22 52 795). Um einen guten Ausnutzungsgrad zu bekommen, hat man die bekannten Entschwefelungsmittel, insbesondere für den Einsatz nach dem Tauchlanzenverfahren,zunächst möglichst feinkörnig mahlen müssen. Danach entsprechen diese Mittel zwar den gestellten Anforderungen, sind jedoch sowohl bezüglich Herstellung als auch Einsatz teuer. Trotz der Feinmahlung mußten zur Erzielung des gewünschten Entschwefelungsgrades verhältnismäßig große Mengen der Entschwefelungsmittel zugesetzt werden.Desulphurization agents based on CaC2-Ca0 and those which can additionally contain fluorspar are known (DE-PS 20 37 758). It is also state of the art to melt metal with technical carbide (approx. 80% by weight CaC 2 , rest Ca0) or also mixtures of such carbide with additives such as lime, coke, gas-releasing substances, e.g. CaCO 3 , CaCN 2 , Ca (OH ) To desulfurize 2 (DE-AS 22 52 795). In order to get a good degree of utilization, the known desulfurization agents, in particular for use by the immersion lance method, first had to be ground as finely as possible. According to this, these agents meet the requirements, but are expensive both in terms of manufacture and use. Despite the fine grinding, relatively large amounts of the desulfurizing agents had to be added to achieve the desired degree of desulfurization.
Aufgabe der vorliegenden Erfindung ist es daher, ein Entschwefelungsmittel zu schaffen, das einen besseren Ausnutzungsgrad bietet, und ein wirtschaftliches Verfahren zur Herstellung dieses Mittels bereitzustellen.It is therefore an object of the present invention to provide a desulfurization agent which offers better utilization and to provide an economical process for the preparation of this agent.
Es wird daher erfindungsgemäß vorgeschlagen, daß im Kristallgemenge ein Teil des Ca0 zu Ca(OH)2 hydratisiert ist. Hierbei geht man vorzugsweise von Kristallgemengen mit einem Anteil von 40 bis 80 Gew% Ca0 (entsprechend 2o bis 60 Gew% CaC2), insbesondere 45 bis 8o Gew% Ca0 (entsprechend 2o bis 55 Gew% CaC2) oder 4o bis 65 Gew% Ca0 (entsprechend 35 bis 6o Gew% CaC2) aus. Das erfindungsgemäße Mittel ist weiterhin bevorzugt dadurch gekennzeichnet, daß Ca0 im Kristallgemenge mit 1 bis 6 Gew% H20, vorzugsweise 2,5 bis 3,5 Gew% H20, bezogen auf die Menge des CaC2-CaO, hydratisiert ist. Beim Erstarren aus dem Schmelzfluß kristallisieren Ca0 und CaC2 als Kristallgemenge, in dem die CaC2-und Ca0-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 Entschwefelungsmittel in eine Metallschmelze eingeblasen wird, so zerfallen die Mahlkörner, die aus CaO-CaC2 Kristallverwachsungen bestehen, in denen ein Teil der Ca0-Kristalle hydratisiert ist, bei den herrschenden Temperaturen oberhalb 800°C nach folgender Reaktionsgleichung
Wegen der Gasentwicklung an den reaktiven Kristallgrenzflächen zerplatztdas 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 in statu nascendi highly reactive lime and with enlargement of the overgrown CaO-CaC 2 crystal surfaces. With an almost eutectic crystal structure, there is an ideally large reaction surface. The released reducing gases offer ideal conditions for the implementation of Ca0 with the sulfur dissolved in the molten metal.
Ein solches Entschwefelungsmittel eignet sich insbesondere hervorragend bei Entschwefelungsprozessen, bei denen die Zeit für den Umsatz des Entschwefelungsmittels mit dem Schwefel sehr kurz ist. Zu diesem Verfahren gehört das Tauchlanzenverfahren, bei dem durch Einblasen von Entschwefelungsmitteln in eine Metallschmelze unterhalb deren Oberfläche in der kurzen Zeit vom Austritt des Entschwefelungsmittels in die Schmelze bis zum Aufsteigen an die Badoberfläche die Umsetzung des Entschwefelungsmittels möglichst vollständig erfolgen sollte.Such a desulfurization agent is particularly suitable for desulfurization processes in which the time for the desulfurization agent to react with the sulfur is very short. This process includes the immersion lance process, in which the desulfurization agent should be converted as completely as possible by blowing desulfurization agents into a molten metal below its surface in the short time from the point at which the desulfurization agent emerges in the melt until it rises to the bath surface.
Das erfindungsgemäße Entschwefelungsmittel zeigt sich den besten bekannten Mitteln 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 Entschwefelungsmitteln, 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 Entschwefelungsmittels als Folge der Vergrößerung der Kristalloberflächen beim Zerplatzen des Mahlkornsin der Schmelze kann das Material grobkörniger eingesetzt werden, so daß teures Feinmahlen entfallen kann.The desulfurization agent according to the invention is superior to the best known carbide-based agents 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 are more effective, the gas development is much more uniform and less violent than with known desulfurization agents, 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 agent 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 size, so that expensive fine grinding can be dispensed with.
Die Verwendung des erfindungsgemäßen Entschwefelungsmittels ermöglicht wegen seiner homogenen Zusammensetzung eine größere Treffsicherheit auf den jeweils geforderten Endgehalt. Die Herstellungskosten für das erfindungsgemäße Mittel liegen erheblich niedriger als für bekannte Mittel auf Carbidbasis.Because of its homogeneous composition, the use of the desulfurization agent according to the invention enables greater accuracy with regard to the final content required in each case. The production costs for the agent according to the invention are considerably lower than for known agents based on carbide.
Weiterhin wird ein Verfahren zur Herstellung des erfindungsgemäßen Mittels vorgeschlagen, welches dadurch gekennzeichnet ist, daß während des Mahlens des im stückigen Material vorliegenden CaC2-CaO-Kristallgemenges H20 zugesetzt wird oder Ca0 im fertigen Mahlkorn teilweise hydratisiert wird.Furthermore, a process for the preparation of the agent according to the invention is proposed, which is characterized in that H 2 0 is added during the grinding of the CaC 2 -CaO crystal mixture present in the particulate material or that Ca0 is partially hydrated in the finished grinding grain.
Insbesondere kann das Verfahren dadurch gekennzeichnet sein, daß man zur Herstellung des Endproduktes,das 2o bis 55 Gew% Calciumcarbid, mehr als 45 bis 8o Gew% Calciumoxid sowie an Calciumoxid chemisch gebundenes Wasser enthält, in eine vorliegende und in üblicher Weise erzeugte Calciumcarbidschmelze, welche bereits einen Calciumoxidgehalt bis 45 Gew% aufweist, feinteiliges Calciumoxid einträgt, in einem Überschuß von 3 bis 15 Gew%, bezogen auf die im Endprodukt gewünschte Menge, dann die erhaltene Mischung unter Erstarren auf Temperaturen von 35o bis 450°C abkühlt, bei diesen Temperaturen auf Korngrößen kleiner als 15o mm vorbricht, den dabei zwangsläufig anfallenden Kornanteil kleiner als 4 mm vom verbleibenden Produkt abtrennt und letzteres in Gegenwart von Luft oder Stickstoff mit einem Feuchtigkeitsgehalt von 5 bis 2o g/m3 (bei 1,013 bar und 273,15 K) durch Brechen und Mahlen bei Temperaturen unterhalb 1oo°C, vorzugsweise von 10 - 50°C, auf Korngrößen kleiner als 1o mm, vorzugsweise kleiner als 0,1 mm, zerkleinert.In particular, the process can be characterized in that, for the production of the end product, which contains 2o to 55% by weight calcium carbide, more than 45 to 8o% by weight calcium oxide and water chemically bound to calcium oxide, calcium carbide melt which is present and produced in a customary manner and which Already has a calcium oxide content of up to 45% by weight, finely divided calcium oxide is introduced in an excess of 3 to 15% by weight, based on the amount desired in the end product, then the mixture obtained cools to temperatures of 35 ° to 450 ° C. with solidification, at these temperatures breaks down to grain sizes smaller than 15o mm, separates the inevitably occurring grain fraction smaller than 4 mm from the remaining product and the latter 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) less than 50 ° C, to particle sizes than 1o mm, pref - by crushing and grinding at temperatures below 1oo ° C, preferably from 1 0 ice smaller than 0.1 mm, crushed.
Wahlweise und bevorzugt ist dieses Herstellungsverfahren dadurch gekennzeichnet, daß
- a) das Endprodukt 1 bis 6 Gew% von an Calciumoxid chemisch gebundenem Wasser enthält,
- b) die Zugabe des Calciumoxids,die sogenannte Magerung des Carbids, unter Ausnutzung des Wärmeinhaltes des Carbids in einem Tiegel durchgeführt wird,
- c) man das Calciumoxid, welches in die Calciumcarbidschmelze eingetragen wird, auf Temperaturen bis zu 2000°C 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 45 und 8o Gew% liegen soll,
- d) von einer Calciumcarbidschmelze ausgegangen wird, welche zwischen 2o und 45 Gew% Calciumoxid enthält,
- e) man die nach dem Vorbrechen abgesiebten Anteile kleiner als 4 mm in den Prozeß zurückführt.
- a) the end product contains 1 to 6% by weight of water chemically bound to calcium oxide,
- b) 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,
- c) the calcium oxide, which is introduced into the calcium carbide melt, is preheated to temperatures of up to 2000 ° C. and introduced hot into the melt, the preheating being chosen to be higher, the higher the desired proportion of additionally dissolved calcium oxide between 45 and 8o % By weight,
- d) a calcium carbide melt is assumed which contains between 2o and 45% by weight calcium oxide,
- e) the portions smaller than 4 mm after the 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 umso höher gewählt wird, je höher der gewünschte Anteil an zusätzlich gelöstem Calciumoxid zwischen 45 und 8o 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 higher the preheating chosen, the higher the desired proportion of additionally dissolved calcium oxide should be between 45 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 anfallenden 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 that have been screened off after the preliminary crushing essentially consist of Ca0 and can be recycled back into the process as finely divided calcium oxide, where they serve as the starting product together with fresh Ca0. It was not foreseeable for the person skilled in the art that the sieving of the An parts smaller than 4 mm are removed from the product, the parts that have no or only a low desulfurization effect, and so the effectiveness of the end product is significantly 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 illustrated by 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 CaO-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 : Ca0-Gewichtsverhältnis von 43 : 57 vorliegt, was einem Überschuß von 14 Gew% Ca0, bezogen auf den im Endprodukt gewünschten Ca0-Gehalt von 50 Gew%, entspricht. Dann wird abgekühlt, bis die Durchschnittstemperatur des dabei erstarrten Carbidblockes etwa 400°C beträgt, und der Block auf Größen kleiner als 15o mm vorgebro- chen.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 : Ca0 weight ratio of 43:57, which corresponds to an excess of 14% by weight Ca0, based on the Ca0 content of 50% by weight desired in the end product. It is then cooled until the average temperature of the solidified carbide block is approximately 400 ° C., and the block is pre-broken 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, das anschließend unter Durchleiten von 1500 m3/h Luft mit einem Feuchtigkeitsgehalt von 1o g/m3 (bei 15°C) in einer Rotationsmühle mit einem Durchsatz von 5oo kg/h bei 5o°C auf Korngrößen kleiner als 0,1 mm gemahlen wird. Die abgesiebte Kornfraktion kleiner als 4 mm wird zusammen mit frischem Kalk (Ca0) wieder als Ausgangsprodukt eingesetzt. Das erhaltene Produkt enthält 2,5 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 contains a crystal mixture of 50% by weight CaC 2 and 50% by weight Ca0 represents that then with passage of 1500 m 3 / h of air with a moisture content of 1o g / m 3 (at 15 ° C) in a rotary mill with a throughput of 5oo kg / h at 5o ° C to grain sizes less than 0.1 mm is ground. The screened grain fraction smaller than 4 mm is used together with fresh lime (Ca0) as the starting product. The product obtained contains 2.5% 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% Ca0.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 Ca0 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.
4,5 % Kohlenstoff, 0,8 % Silizium, 0,7 % Mangan, 0,08 % Phosphor, 0,064 % Schwefel, Rest Eisen wurde nach dem Tauchlanzenverfahren mit dem erfindungsgemäßen Entschwefelungsmittel der Zusammensetzung je 50 Gew% CaC2 und CaO, hydratisiert mit etwa 3 Gew% H20, in einer offenen Pfanne entschwefelt. Die Tauchtiefe der Lanze betrug 1,8 m. Die Einblasgeschwindigkeit betrug 100 kg/min. Der Gesamtverbrauch des Entschwefelungsmittels 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 made by the immersion lance method with the decoating agent according to the invention Melting agent of the composition 50% by weight of CaC 2 and CaO, hydrated with about 3% by weight of H 2 O, desulfurized in an open pan. The depth of the lance was 1.8 m. The blowing speed was 100 kg / min. The total consumption of the desulfurization agent 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%.
Bei dem erfindungsgemäßen Entschwefelungsmittel ergibt sich gegenüber dem bei diesem Vergleichsversuch benutzten bekannten Entschwefelungsmittel eine Ersparnis von 25 %, bezogen auf die absolute Menge an Entschwefelungsmittel, und eine Ersparnis von 45 %, bezogen auf den CaC2-Anteil. Im selben Maß verkürzt sich auch die Behandlungszeit.In the desulfurizing agent according to the invention, compared to the known desulfurizing agent used in this comparative experiment, there is a saving of 25%, based on the absolute amount of desulfurizing agent, and a saving of 45%, based on the CaC 2 content. The treatment time is shortened to the same extent.
Claims (14)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT80108013T ATE10382T1 (en) | 1979-12-29 | 1980-12-18 | DESULPHURIZING AGENT AND PROCESS FOR ITS PRODUCTION. |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19792952761 DE2952761A1 (en) | 1979-12-29 | 1979-12-29 | Desulphurising of molten metals, esp. crude iron or steel - using mixed crystals of calcium carbide and calcium oxide which is partly hydrated |
DE2952761 | 1979-12-29 | ||
DE3008950 | 1980-03-08 | ||
DE19803008950 DE3008950C2 (en) | 1980-03-08 | 1980-03-08 | Desulphurising agent and process for its preparation |
Publications (2)
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EP0031552A1 true EP0031552A1 (en) | 1981-07-08 |
EP0031552B1 EP0031552B1 (en) | 1984-11-21 |
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EP80108013A Expired EP0031552B1 (en) | 1979-12-29 | 1980-12-18 | Desulphurising composition and process for its production |
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---|---|
US (1) | US4358312A (en) |
EP (1) | EP0031552B1 (en) |
AU (1) | AU532988B2 (en) |
BR (1) | BR8008513A (en) |
CA (1) | CA1154596A (en) |
DD (1) | DD155528A5 (en) |
DE (1) | DE3069681D1 (en) |
DK (1) | DK151570C (en) |
ES (1) | ES8200147A1 (en) |
MX (1) | MX154953A (en) |
NO (1) | NO153499C (en) |
PL (1) | PL125943B1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0061012A1 (en) * | 1981-03-24 | 1982-09-29 | Hoechst Aktiengesellschaft | Process for producing desulfurizing agents for pig iron and steel melts |
EP0061011A1 (en) * | 1981-03-24 | 1982-09-29 | Hoechst Aktiengesellschaft | Process for producing desulfurizing agents for pig iron or steel melts |
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 (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3110569A1 (en) * | 1981-03-18 | 1982-12-30 | Skw Trostberg Ag, 8223 Trostberg | METHOD FOR PREVENTING OVERFLOWING WHEN REFRESHING IRON AND FOR REDUCING PHOSPHORUS CONTENT, MEANS AND DEVICE FOR IMPLEMENTING THE METHOD |
DE3908071A1 (en) * | 1989-03-13 | 1990-09-20 | Hoechst Ag | MEANS AND METHOD FOR DISCHARGING METAL MELTS |
DE4242328C2 (en) * | 1992-12-15 | 1995-06-08 | Alfred Dipl Ing Dr Freissmuth | Means for desulfurization, dephosphorization, desiliconization and denitrification of pig iron and cast iron melts |
PL213251B1 (en) | 2009-02-02 | 2013-02-28 | Akad Gorniczo Hutnicza | Method of manufacturing slag-forming mixture for the secondary steel refining in a ladle or in a ladle furnace |
Citations (1)
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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 |
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GB1005163A (en) * | 1963-08-10 | 1965-09-22 | British Cast Iron Res Ass | Improvements in the manufacture of inoculants for cast irons |
CH428820A (en) * | 1963-12-12 | 1967-01-31 | Tech Entwicklung Und Verwertun | Steel refining product |
US3197306A (en) * | 1964-08-31 | 1965-07-27 | Dow Chemical Co | Method for treating ferrous metals |
DE1758250B1 (en) * | 1968-04-29 | 1971-10-28 | Sueddeutsche Kalkstickstoff | Agent for the desulphurisation of iron melts |
US3716352A (en) * | 1969-10-24 | 1973-02-13 | Kawasaki Steel Co | Sintered desulfurizer for off-furnace use |
DE2252795C3 (en) * | 1972-10-27 | 1982-09-09 | Skw Trostberg Ag, 8223 Trostberg | Desulphurizing agent for pig iron and ferro-alloy melts |
DE2527156B2 (en) * | 1975-06-18 | 1980-09-04 | Thyssen Niederrhein Ag Huetten- Und Walzwerke, 4200 Oberhausen | Process for the pretreatment of molten steel in continuous casting |
JPS605643B2 (en) * | 1975-11-14 | 1985-02-13 | 電気化学工業株式会社 | Production method of hot metal desulfurization agent |
JPS6035407B2 (en) * | 1978-05-31 | 1985-08-14 | 電気化学工業株式会社 | Desulfurization agent for hot metal and its manufacturing method |
DE2919324A1 (en) * | 1979-05-14 | 1980-12-04 | Hoechst Ag | DEHANIZER FOR RAW IRON AND STEEL MELTING AND A METHOD FOR THE PRODUCTION THEREOF |
DE2952686A1 (en) * | 1979-12-29 | 1981-07-02 | Hoechst Ag, 6230 Frankfurt | METHOD FOR THE PRODUCTION OF DESULFURING AGENTS FOR BOD IRON OR STEEL MELT |
-
1980
- 1980-12-12 ES ES497686A patent/ES8200147A1/en not_active Expired
- 1980-12-18 DE DE8080108013T patent/DE3069681D1/en not_active Expired
- 1980-12-18 EP EP80108013A patent/EP0031552B1/en not_active Expired
- 1980-12-22 US US06/218,731 patent/US4358312A/en not_active Expired - Fee Related
- 1980-12-23 BR BR8008513A patent/BR8008513A/en unknown
- 1980-12-23 PL PL1980228753A patent/PL125943B1/en unknown
- 1980-12-23 DK DK550980A patent/DK151570C/en not_active IP Right Cessation
- 1980-12-23 NO NO803923A patent/NO153499C/en unknown
- 1980-12-24 CA CA000367572A patent/CA1154596A/en not_active Expired
- 1980-12-24 AU AU65853/80A patent/AU532988B2/en not_active Ceased
- 1980-12-29 DD DD80226700A patent/DD155528A5/en not_active IP Right Cessation
-
1981
- 1981-01-05 MX MX185476A patent/MX154953A/en unknown
Patent Citations (1)
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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 |
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PATENTS ABSTRACTS OF JAPAN, Band 1, Nr. 120, 12.Oktober 1977 Seite 2840 C 78 & JP - A - 53 99023. * |
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Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0061012A1 (en) * | 1981-03-24 | 1982-09-29 | Hoechst Aktiengesellschaft | Process for producing desulfurizing agents for pig iron and steel melts |
EP0061011A1 (en) * | 1981-03-24 | 1982-09-29 | Hoechst Aktiengesellschaft | Process for producing desulfurizing agents for pig iron or steel melts |
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 |
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NO153499B (en) | 1985-12-23 |
US4358312A (en) | 1982-11-09 |
DD155528A5 (en) | 1982-06-16 |
CA1154596A (en) | 1983-10-04 |
DE3069681D1 (en) | 1985-01-03 |
PL228753A1 (en) | 1981-09-04 |
AU6585380A (en) | 1981-07-09 |
ES497686A0 (en) | 1981-11-01 |
DK151570B (en) | 1987-12-14 |
DK550980A (en) | 1981-06-30 |
EP0031552B1 (en) | 1984-11-21 |
MX154953A (en) | 1988-01-14 |
PL125943B1 (en) | 1983-06-30 |
NO803923L (en) | 1981-06-30 |
NO153499C (en) | 1986-04-02 |
BR8008513A (en) | 1981-07-21 |
DK151570C (en) | 1988-06-06 |
ES8200147A1 (en) | 1981-11-01 |
AU532988B2 (en) | 1983-10-20 |
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