EP0135078A2 - Rotary drum furnace and its use - Google Patents

Rotary drum furnace and its use Download PDF

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Publication number
EP0135078A2
EP0135078A2 EP84108997A EP84108997A EP0135078A2 EP 0135078 A2 EP0135078 A2 EP 0135078A2 EP 84108997 A EP84108997 A EP 84108997A EP 84108997 A EP84108997 A EP 84108997A EP 0135078 A2 EP0135078 A2 EP 0135078A2
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EP
European Patent Office
Prior art keywords
rotary
gas
tube
rotary tube
rotary kiln
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EP84108997A
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German (de)
French (fr)
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EP0135078A3 (en
EP0135078B2 (en
EP0135078B1 (en
Inventor
Helmut Dipl.-Ing. Janz
Fritz Dr. Rodi
Alfred Dipl.-Ing. Soppe
Jakob Dr. Rademachers
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Bayer AG
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Bayer AG
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/14—Rotary-drum furnaces, i.e. horizontal or slightly inclined with means for agitating or moving the charge
    • F27B7/16—Rotary-drum furnaces, i.e. horizontal or slightly inclined with means for agitating or moving the charge the means being fixed relatively to the drum, e.g. composite means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B11/00—Machines or apparatus for drying solid materials or objects with movement which is non-progressive
    • F26B11/02—Machines or apparatus for drying solid materials or objects with movement which is non-progressive in moving drums or other mainly-closed receptacles
    • F26B11/04—Machines or apparatus for drying solid materials or objects with movement which is non-progressive in moving drums or other mainly-closed receptacles rotating about a horizontal or slightly-inclined axis
    • F26B11/0463—Machines or apparatus for drying solid materials or objects with movement which is non-progressive in moving drums or other mainly-closed receptacles rotating about a horizontal or slightly-inclined axis having internal elements, e.g. which are being moved or rotated by means other than the rotating drum wall
    • F26B11/0477—Machines or apparatus for drying solid materials or objects with movement which is non-progressive in moving drums or other mainly-closed receptacles rotating about a horizontal or slightly-inclined axis having internal elements, e.g. which are being moved or rotated by means other than the rotating drum wall for mixing, stirring or conveying the materials to be dried, e.g. mounted to the wall, rotating with the drum
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/08—Rotary-drum furnaces, i.e. horizontal or slightly inclined externally heated
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/14—Rotary-drum furnaces, i.e. horizontal or slightly inclined with means for agitating or moving the charge
    • F27B7/16—Rotary-drum furnaces, i.e. horizontal or slightly inclined with means for agitating or moving the charge the means being fixed relatively to the drum, e.g. composite means
    • F27B7/161—Rotary-drum furnaces, i.e. horizontal or slightly inclined with means for agitating or moving the charge the means being fixed relatively to the drum, e.g. composite means the means comprising projections jutting out from the wall

Definitions

  • the present invention relates to a rotary tube furnace for carrying out gas-solid reactions, consisting of an indirectly heated, rotating reaction tube with internal fittings, which is provided with feed and discharge devices for solids and gas inlet and outlet lines.
  • the invention relates to the use of the rotary kiln.
  • Rotary tube furnaces are used to carry out numerous reactions between gases and free-flowing, non-sticky solids (Chem.-Ing.-Techn. 51 (1979) No. 8, pp. 771-778; Verlag Chemie, Weinheim).
  • Indirectly heated rotary kilns are used in particular in those processes in which a gas flow and gas composition that is independent of the type and quantity of flue gas is required within the rotary tube.
  • Such indirectly heated furnaces can be equipped with both electrical heating elements and burners. Even with oil or gas-fired ovens, the external heating leads to a gas routing and gas composition within the rotary tube that is independent of the type and quantity of flue gas. Desired temperature profiles can be set using separately adjustable heating zones.
  • Such rotary kilns can be operated gas-tight, they allow operation under increased gas pressure. Therefore, they are preferably used for carrying out reactions in a desired gas atmosphere with the complete exclusion of atmospheric oxygen. They have become particularly interesting for reactions in which there is an increased risk of forming explosive mixtures with air, as is the case with highly flammable gases and finely divided, pyrophoric powders.
  • Rotary kilns have the advantage of continuous reaction control in the moving bed. However, they have the disadvantage of cross and longitudinal mixing during the passage of the reactants through the furnace. As a result, the individual particles experience different reaction conditions in accordance with their different residence times in the individual zones.
  • the mean residence time of the individual particles is difficult to calculate in advance. she can only be determined experimentally, for example by doping. In general, relatively wide dwell times are obtained under these circumstances. This means a different treatment time for the individual grain, which can lead to a significant quality disadvantage for sensitive products.
  • the aim of this invention is to provide a rotary kiln in which it is possible to achieve the narrowest possible residence spectrum with the best possible contact between gas and solid.
  • the rotary kiln according to the invention for carrying out gas-solid reactions consisting of an indirectly heated, rotating and equipped with feed and discharge devices for solids and gas inlet and outlet lines, is characterized in that the internals consist of one over the entire Kiln length running, closed on both sides central tube and a coil, which in turn is tightly connected to both the central tube and the outer rotary tube.
  • the inner circumference of the outer rotary tube is additionally provided with lifting blades.
  • These lifting blades can NEN can be arranged in the rotary kiln as needed, but generally offers an even distribution.
  • the rotary tube should be gas-tight for most reactions.
  • the aforementioned internals contained in the rotary tube hereinafter referred to as a closed helix with lifting blades, are particularly effective if the reaction gas which is moved helically around the central tube is conducted in countercurrent to the solid.
  • a gas chamber in each helix chamber that is loaded with solids, which is generated by the product veils trickling off the lifting blades.
  • these zones are comparable to mechanically supported fluidized beds.
  • the number of turns over the length of the rotary tube corresponds to the number of fluidized beds connected in series.
  • This rotary tube which is to be regarded as a multistage fluidized bed reactor, should be treated with solid matter as evenly as possible in the free space of each turn due to the intensive gas contact. It has been found here that the lifting blades are expediently positioned positively depending on the angle of repose and the free-flowing properties of the product. Accordingly, during operation a higher pressure difference between the gas entry and exit points. It has been found that with a good solids distribution in the gas space, the pressure loss generated by the fluidized bed is many times higher than the pressure loss which is caused only by the curved channel flow with the bed at rest.
  • the height of the lifting vanes is advantageously dimensioned such that the rest of the solid falling off the lifting vanes does not yet touch the inner central tube. This ensures that the product is not mixed from one spiral chamber into the other.
  • the advantage of the rotary kiln according to the invention is an improved contact of gas and solid, corresponding to an increased utilization of the gas to be reacted in countercurrent flow.
  • the capacity of the rotary kiln according to the invention can be significantly increased without having to accept a deterioration in the product.
  • the quality properties can be improved.
  • the required oven temperatures can often be reduced with the same or a shorter residence time, which, in addition to saving heating energy, also improves the material properties for thermosensitive materials.
  • the influence of the grain spectrum on the product quality is strongly suppressed, thus achieving a homogeneous product quality.
  • the rotary kiln according to the invention is technically versatile in use for continuously conducted reaction processes of gases with free-flowing, non-sticky solids. In principle, it can also be used for thermal treatments such as for heating or cooling processes or for tempering in various gas atmospheres. It is irrelevant whether chemical reactions or only physical processes such as heat transfers from gas to solid occur in the material to be treated.
  • Another object of the present invention is therefore the use of the rotary kiln for various processes.
  • this includes the use of the rotary kiln according to the invention for oxidation, reduction, chlorination, roasting, digestion, catalysis, tempering or cooling processes.
  • the subject of the present invention preferably includes the use Extension of the rotary kiln for the production of fine-particle metals or metal oxides by reducing higher-quality oxides with reducing gases, in particular for the production of fine-particle iron oxides with a defined degree of oxidation and metallic iron for magnetic recording purposes.
  • the advantage of the use according to the invention comes into play, since these products tend to sinter sintering due to their fine-particle nature during temperature treatments.
  • metals such as tungsten, copper or nickel can also advantageously be obtained in the rotary tube furnace according to the invention.
  • the production of mixed phase pigments, activated carbon and ceramic solids in such furnaces is made possible, to give just a few examples.
  • Fig. 1 the solid is fed into the rotary tube via a product task 1. It is continued in the indicated direction of travel through the helix 5 tightly installed between the outer rotary tube 9 and the inner central tube 6 in accordance with the number of revolutions of the rotary tube.
  • the treated product exits the rotary tube at 2.
  • the reaction or process gas is fed to the rotary tube at 3.
  • the inner central tube 6 is provided with sealing plugs 7 at both ends. At 4, the gas is discharged from the rotating reaction tube.
  • FIG. 2 the portion of the solids can be seen schematically above the cross section, which rests as a bed on the lifting blades 8, which are evenly arranged over the inner handling of the outer rotary kiln 9.
  • FIG. 10 the direction of rotation of the gas flow is opposite to the product curtains falling off the blades 8, and in FIG. 11 the direction of rotation of the reaction tube is shown.
  • the dimensioning of the internals depends on the intended volume flows, the required material ratios and the product-specific properties of the reactants.
  • the grain size, particle size distribution, angle of repose and density of the solids, and to a lesser extent the viscosity and density of the gases, are key factors that also play an important role in fluid bed technology.
  • variable parameters are feed quantity, T em peraturprofil, speed of rotation of the rotating tube, gas quantity, inert gas and outlet temperature of gas and solid.
  • the speed should be selected so that the material is raised enough times. If the rotation is too low, the bed will rest on the lifting blades. If, at normal speeds, the dwell time for a given reactor length is not sufficient for complete conversion, it makes sense to operate the rotating tube alternately in both directions of rotation, with the direction of rotation that is decisive for product passage prevailing over time. This measure gives longer dwell times at the same speed. The setting of the lifting blades no longer has an advantageous effect in this special procedure.
  • the degree of filling of the rotary tube is preferably set so that the product does not overshoot via the lifting blades.
  • Needle-shaped oe -Fe 2 0 3 (hematite) obtained by dewatering ⁇ -FeOOH (goethite) with a grain size of 0.5 to 2 mm and a spec.
  • Surface of 29 m 2 / g is continuously fed from a storage bunker into the rotary kiln via a belt weigher.
  • the indirectly heatable, gas-tight rotary tube has a heating section of 2 m divided into three separately controllable zones with an inner diameter of 30 cm.
  • the internal internals consist of the closed helix with 43 turns.
  • 16 hib scoops are mounted, distributed evenly over the circumference, at an angle of 25 °.
  • the height of the lifting blades is 35 mm.
  • the central tube has a diameter of 76 mm.
  • the channel length is approx. 25 m.
  • ⁇ -FeOOH (goethite) is added in an amount of 2 kg / h.
  • the grain size of the material fed is between 0.5 and 2 mm.
  • the spec. The surface is 56 m 2 / g.
  • the temperatures of the reaction tube rotating at a 4% incline and 2 rpm are set to about 430 ° C. in the three heating zones.
  • the amount of hydrogen supplied in counterflow is 15 Nm 3 / h.
  • 2 N m 3 / h of nitrogen are introduced via the furnace heads.
  • 1.25 kg of pyrophoric iron with a metal content of 98.5% are obtained per hour.
  • the surface of the needle-shaped iron is 20 m 2 / g, the coercive force is 1100 Oe.
  • the product is particularly suitable for incorporation into magnetic tapes.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Muffle Furnaces And Rotary Kilns (AREA)
  • Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)
  • Manufacture Of Iron (AREA)
  • Compounds Of Iron (AREA)
  • Catalysts (AREA)

Abstract

Die vorliegende Erfindung betrifft einen Drehrohrofen für die Durchführung von Gas-Feststoff-Reaktionen, bestehend aus einem indirekt beheizten, rotierenden und mit Auf- und Abgabevorrichtungen für Feststoffe und Gasein- und ableitungen versehenen Reaktionsrohr mit inneren Einbauten.The present invention relates to a rotary tube furnace for carrying out gas-solid reactions, consisting of an indirectly heated, rotating and provided with feed and discharge devices for solids and gas inlet and outlet reaction tube with internal internals.

Description

Die vorliegende Erfindung betrifft einen Drehrohrofen für die Durchführung von Gas-Feststoff-Reaktionen, bestehend aus einem indirekt beheizten, rotierenden und mit Auf- und Abgabevorrichtungen für Feststoffe und Gasein-und ableitungen versehenen Reaktionsrohr mit inneren Einbauten.The present invention relates to a rotary tube furnace for carrying out gas-solid reactions, consisting of an indirectly heated, rotating reaction tube with internal fittings, which is provided with feed and discharge devices for solids and gas inlet and outlet lines.

Weiterhin betrifft die Erfindung die Verwendung des Drehrohrofens.Furthermore, the invention relates to the use of the rotary kiln.

Drehrohröfen werden für die Durchführung zahlreicher Reaktionen zwischen Gasen und rieselfähigen, nicht klebenden Feststoffen eingesetzt (Chem.-Ing.-Techn. 51 (1979) Nr. 8, S. 771-778; Verlag Chemie, Weinheim).Rotary tube furnaces are used to carry out numerous reactions between gases and free-flowing, non-sticky solids (Chem.-Ing.-Techn. 51 (1979) No. 8, pp. 771-778; Verlag Chemie, Weinheim).

Indirekt beheizte Drehrohröfen werden insbesondere bei solchen Prozessen eingesetzt, bei denen eine von der Rauchgasart und -menge unabhängige Gasführung und Gaszusammensetzung innerhalb des Drehrohres benötigt wird. Derartig indirekt beheizte öfen können sowohl mit elektrischen Heizelementen als auch mit Brennern ausgerüstet sein. Selbst bei öl- oder gasbeheizten öfen führt die AuBenheizung zu einer von der Rauchgasart und -menge unabhängigen Gasführung und Gaszusammensetzung innerhalb des Drehrohres. Gewünschte Temperaturprofile können durch getrennt regelbare Heizzonen eingestellt werden.Indirectly heated rotary kilns are used in particular in those processes in which a gas flow and gas composition that is independent of the type and quantity of flue gas is required within the rotary tube. Such indirectly heated furnaces can be equipped with both electrical heating elements and burners. Even with oil or gas-fired ovens, the external heating leads to a gas routing and gas composition within the rotary tube that is independent of the type and quantity of flue gas. Desired temperature profiles can be set using separately adjustable heating zones.

Da solche Drehrohröfen gasdicht betrieben werden können, erlauben sie eine Fahrweise unter erhöhtem Gasdruck. Deshalb werden sie für die Durchführung von Reaktionen in einer gewünschten Gasatmosphäre unter völligem Ausschluß von Luftsauerstoff bevorzugt eingesetzt. Besonders sind sie für Reaktionen interessant geworden, bei denen eine erhöhte Gefahr zur Bildung explosiver Gemische mit Luft besteht, wie es bei leicht entzündlichen Gasen und feinteiligen, pyrophoren Pulvern der Fall ist.Since such rotary kilns can be operated gas-tight, they allow operation under increased gas pressure. Therefore, they are preferably used for carrying out reactions in a desired gas atmosphere with the complete exclusion of atmospheric oxygen. They have become particularly interesting for reactions in which there is an increased risk of forming explosive mixtures with air, as is the case with highly flammable gases and finely divided, pyrophoric powders.

Drehrohröfen haben den Vorteil der kontinuierlichen Reaktionsführung im bewegten Bett. Sie weisen aber den Nachteil der Quer- und Längsvermischung während des Durchgangs der Reaktionspartner durch den Ofen auf. Hierdurch erfahren die Einzelpartikel verschiedene Reaktionsbedingungen entsprechend ihrer unterschiedlichen Verweilzeit in den einzelnen Zonen.Rotary kilns have the advantage of continuous reaction control in the moving bed. However, they have the disadvantage of cross and longitudinal mixing during the passage of the reactants through the furnace. As a result, the individual particles experience different reaction conditions in accordance with their different residence times in the individual zones.

Ändern sich aber die Eigenschaften der Feststoffe während der Reaktion, so läßt sich die mittlere Verweilzeit der Einzelpartikel nur noch schwer vorherberechnen. Sie kann nur noch experimentell, beispielsweise durch Dotierung, ermittelt werden. Allgemein werden unter diesen Umständen relativ breite Verweilzeitsprektren erhalten. Das bedeutet eine für das Einzelkorn unterschiedliche Behandlungsdauer, die bei empfindlichen Produkten zu einem deutlichen Qualitätsnachteil führen kann.However, if the properties of the solids change during the reaction, the mean residence time of the individual particles is difficult to calculate in advance. she can can only be determined experimentally, for example by doping. In general, relatively wide dwell times are obtained under these circumstances. This means a different treatment time for the individual grain, which can lead to a significant quality disadvantage for sensitive products.

Das Ziel dieser Erfindung besteht darin, einen Drehrohrofen bereitzustellen, in dem es möglich ist, ein möglichst enges Verweilspektrum bei möglichst gutem Kontakt zwischen Gas und Feststoff zu erzielen.The aim of this invention is to provide a rotary kiln in which it is possible to achieve the narrowest possible residence spectrum with the best possible contact between gas and solid.

Bisher sind bereits Maßnahmen zur Erzielung engerer Verweilzeitspektren bekannt geworden. So ist es heute üblich, mit der Ofenwand fest verbundene Wendeln einzubauen, die auf das Produkt eine Zwangsförderung ausüben. Auch sind Maßnahmen beschrieben, die einen besseren Kontakt von Gas und Feststoff herbeiführen sollen. So werden beispielsweise Wendeleisten oder Hubschaufeln eingebaut, die das Produkt anheben und quer zur Gasströmung abfallen lassen.So far, measures to achieve narrow residence time spectra have become known. It is common today to install spirals that are firmly connected to the furnace wall and that force-convey the product. Measures are also described which are intended to bring about better contact between gas and solid. For example, spiral bars or lifting blades are installed, which lift the product and drop it across the gas flow.

Es ist aus der DE-A 3 025 716 eine Vorrichtung bekannt geworden, die bei einheitlicher Verweilzeit durch wendelförmige Zwangsförderung einen besseren Kontakt von Gas und Feststoff ergibt, indem das Gas ebenfalls entlang der wendelförmigen Bahn geleitet wird. Der Nachteil dieses indirekt beheizten, rotierenden wendelförmigen Reaktionsrohres besteht darin, daß die Zuführung des Feststoffes schwierig ist und in der normalen Ausführungsform bei jeder Umdrehung des Wendelrohres intermittierend erfolgt. Ein weiterer Nachteil ergibt sich dadurch, daß die reaktionsfähigen Gase nur oberhalb der Schüttung entlang geleitet werden können, infolgedessen kann kein sehr hoher Nutzungsgrad des Gases erreicht werden.From DE-A 3 025 716 a device has become known which, with a uniform dwell time, results in better contact of gas and solid by helical forced conveyance, in that the gas is also passed along the helical path. The disadvantage of this indirectly heated, rotating helical reaction tube is that the supply of the solid is difficult and in the normal embodiment takes place intermittently with every revolution of the helical tube. Another disadvantage arises the fact that the reactive gases can only be passed along above the bed, consequently a very high degree of utilization of the gas cannot be achieved.

Es gelang nun, einen solchen Drehrohrofen zu konstruieren, der die genannten Forderungen hervorragend erfüllt, ohne die oben beschriebenen Nachteile aufzuweisen.It has now been possible to construct a rotary kiln of this type which fulfills the stated requirements excellently without having the disadvantages described above.

Der erfindungsgemäße Drehrohrofen für die Durchführung von Gas-Feststoff-Reaktionen, bestehend aus einem indirekt beheizten, rotierenden und mit Auf- und Abgabevorrichtungen für Feststoffe und Gasein- und ableitungen versehenen Reaktionsrohr mit inneren Einbauten ist dadurch gekennzeichnet, daß die Einbauten aus einem über die gesamte Ofenlänge verlaufenden, beidseitig geschlossenen Zentralrohr und einer Wendelung, die ihrerseits sowohl mit dem Zentralrohr und dem äußeren Drehrohr dicht verbunden ist, bestehen.The rotary kiln according to the invention for carrying out gas-solid reactions, consisting of an indirectly heated, rotating and equipped with feed and discharge devices for solids and gas inlet and outlet lines, is characterized in that the internals consist of one over the entire Kiln length running, closed on both sides central tube and a coil, which in turn is tightly connected to both the central tube and the outer rotary tube.

In einem solchen Drehrohrofen geschieht eine Zwangsförderung ohne Rückvermischung durch die geschlossenen Wendel. Dies bedingt ein enges Verweilzeitspektrum der Einzelteilchen; jedes Feststoffteilchen erfährt somit die gleichen Bedingungen und zeigt gleiche Eigenschaften auf.In such a rotary kiln, forced conveyance takes place through the closed helix without backmixing. This calls for a narrow residence of E inzelteilchen; each solid particle therefore experiences the same conditions and shows the same properties.

In einer besonders bevorzugten Ausführungsform der Erfindung ist zusätzlich der innere Umfang des äußeren Drehrohres mit Hubschaufeln versehen. Diese Hubschaufeln können im Drehrohrofen je nach Bedarf angeordnet sein, wobei sich im allgemeinen aber eine gleichmäßige Verteilung anbietet.In a particularly preferred embodiment of the invention, the inner circumference of the outer rotary tube is additionally provided with lifting blades. These lifting blades can NEN can be arranged in the rotary kiln as needed, but generally offers an even distribution.

Zur Durchführung der meisten Reaktionen sollte das Drehrohr gasdicht abgeschlossen sein.The rotary tube should be gas-tight for most reactions.

Die vorgenannten im Drehrohr enthaltenen Einbauten, im folgenden als geschlossene Wendel mit Hubschaufeln bezeichnet, sind besonders wirkungsvoll, wenn das wendelförmig um das Zentralrohr bewegte Reaktionsgas'im Gegenstrom zum Feststoff geführt wird. In der Freizone zwischen Zentralrohr und Hubschaufeln liegt in jeder Wendelkammer ein feststoffbeladener Gasraum vor, der durch die von den aufwärtsgeführten Hubschaufeln abrieselnden Produktschleier erzeugt wird. Bei Gegenstromführung von Gas und Feststoff sind diese Zonen mit mechanisch unterstützten Wirbelschichten vergleichbar. Die Anzahl der Windungen über die Länge des Drehrohres entspricht der Anzahl der hintereinandergeschalteten Wirbelschichten.The aforementioned internals contained in the rotary tube, hereinafter referred to as a closed helix with lifting blades, are particularly effective if the reaction gas which is moved helically around the central tube is conducted in countercurrent to the solid. In the free zone between the central tube and the lifting blades, there is a gas chamber in each helix chamber that is loaded with solids, which is generated by the product veils trickling off the lifting blades. When gas and solids are countercurrented, these zones are comparable to mechanically supported fluidized beds. The number of turns over the length of the rotary tube corresponds to the number of fluidized beds connected in series.

Dieses als vielstufenwirbelschichtreaktor anzusehende Drehrohr sollte im Freiraum jeder Wendelung wegen des intensiven Gaskontaktes möglichst gleichmäßig mit Feststoff beaufschlagt werden. Hier hat sich herausgestellt, daß zweckmäßig die Hubschaufeln in Abhängigkeit von Schüttwinkel und Rieselfähigkeit des Produktes positiv angestellt werden. Entsprechend ergibt sich während des Betriebes eine höhere Druckdifferenz zwischen den Gasein- und -austrittstellen. Es wurde nämlich festgestellt, daß bei guter Feststoffverteilung im Gasraum der durch die Wirbelschicht erzeugte Druckverlust um ein Vielfaches höher liegt als der Druckverlust, der lediglich durch die gekrümmte Kanalströmung mit ruhender Schüttung hervorgerufen wird.This rotary tube, which is to be regarded as a multistage fluidized bed reactor, should be treated with solid matter as evenly as possible in the free space of each turn due to the intensive gas contact. It has been found here that the lifting blades are expediently positioned positively depending on the angle of repose and the free-flowing properties of the product. Accordingly, during operation a higher pressure difference between the gas entry and exit points. It has been found that with a good solids distribution in the gas space, the pressure loss generated by the fluidized bed is many times higher than the pressure loss which is caused only by the curved channel flow with the bed at rest.

Die Höhe der Hubschaufeln, in Fig. 2 mit h bezeichnet, wird vorteilhafterweise so bemessen, daß der Rest des von den Hubschaufeln abfallenden Feststoffes noch gerade nicht das innere Zentralrohr berührt. Hierdurch ist gewährleistet, daß keine Vermischung des Produktes von einer Wendelkammer in die anderen erfolgt.The height of the lifting vanes, designated h in FIG. 2, is advantageously dimensioned such that the rest of the solid falling off the lifting vanes does not yet touch the inner central tube. This ensures that the product is not mixed from one spiral chamber into the other.

Der Vorteil des erfindungsgemäßen Drehrohrofens besteht in einem verbesserten Kontakt von Gas und Feststoff, entsprechend einer verstärkten Ausnutzung des zu reagierenden Gases bei Gegenstromführung.The advantage of the rotary kiln according to the invention is an improved contact of gas and solid, corresponding to an increased utilization of the gas to be reacted in countercurrent flow.

Gleichzeitig ergibt sich ein enges Verweilzeitsprektrum der Feststoffteilchen. Die Steuerung der Verweilzeit wird vereinfacht, da sie in großen Bereichen nur noch von der Drehzahl und nicht mehr von Aufgabemenge und Ofenneigung beeinflußt wird. Ebenfalls läßt sich der Füllgrad des Drehrohres leichter einstellen, da er von der Aufgabemenge und weniger von Drehzahl und Neigung des Ofens abhängt.At the same time, there is a narrow range of residence times for the solid particles. The control of the dwell time is simplified, since in large areas it is only influenced by the speed and no longer by the quantity and the inclination of the furnace. The degree of filling of the rotary tube can also be adjusted more easily, since it depends on the feed quantity and less on the speed and inclination of the furnace.

Die Kapazität des erfindungsgemäßen Drehrohrofens kann im Vergleich zu herkömmlichen Verfahren wesentlich gesteigert werden, ohne eine Verschlechterung des Produktes in Kauf nehmen zu müssen. In vielen Fällen lassen sich die Qualitätseigenschaften verbessern. Die erforderlichen Ofentemperaturen können häufig bei gleicher oder verkürzter Verweilzeit erniedrigt werden, wodurch neben Einsparung von Heizenergie Verbesserungen der Materialeigenschaften für thermoempfindliche Stoffe erzielt werden. Der Einfluß des Kornspektrums auf die Produktqualität wird stark zurückgedrängt, somit eine homogene Produktqualität erreicht.The capacity of the rotary kiln according to the invention can compared to conventional processes can be significantly increased without having to accept a deterioration in the product. In many cases, the quality properties can be improved. The required oven temperatures can often be reduced with the same or a shorter residence time, which, in addition to saving heating energy, also improves the material properties for thermosensitive materials. The influence of the grain spectrum on the product quality is strongly suppressed, thus achieving a homogeneous product quality.

Der erfindungsgemäße Drehrohrofen ist technisch vielseitig einsetzbar für kontinuierlich geführte Reaktionsprozesse von Gasen mit rieselfähigen, nicht klebenden Feststoffen. Er kann auch prinzipiell für thermische Behandlungen, wie für Aufheiz- oder Abkühlvorgänge oder für Temperungen in verschiedenen Gasatmosphären eingesetzt werden. Es ist hierbei unerheblich, ob in dem zu behandelnden Gut chemische Reaktionen oder nur physikalische Prozesse, wie Wärmeübergänge von Gas auf Feststoff, ablaufen.The rotary kiln according to the invention is technically versatile in use for continuously conducted reaction processes of gases with free-flowing, non-sticky solids. In principle, it can also be used for thermal treatments such as for heating or cooling processes or for tempering in various gas atmospheres. It is irrelevant whether chemical reactions or only physical processes such as heat transfers from gas to solid occur in the material to be treated.

Ein weiterer Gegenstand der vorliegenden Erfindung ist daher auch die Verwendung des Drehrohrofens für verschiedene Verfahren. Beispielsweise gehört hierzu die Verwendung des erfindungsgemäßen Drehrohrofens für Oxidations-, Reduktions-, Chlorierungs-, Abröst-, Aufschluß-, Katalyse-, Temper- oder Abkühlprozesse. Zum Gegenstand der vorliegenden Erfindung gehört bevorzugt die Verwendung des Drehrohrofens für die Herstellung feinteiliger Metalle oder Metalloxide durch Reduktion höherwertiger Oxide mit reduzierenden Gasen, insbesondere zur Herstellung von feinteiligen Eisenoxiden mit definiertem Oxidationsgrad und metallischem Eisen für magnetische Aufzeichnungszwecke.Another object of the present invention is therefore the use of the rotary kiln for various processes. For example, this includes the use of the rotary kiln according to the invention for oxidation, reduction, chlorination, roasting, digestion, catalysis, tempering or cooling processes. The subject of the present invention preferably includes the use Extension of the rotary kiln for the production of fine-particle metals or metal oxides by reducing higher-quality oxides with reducing gases, in particular for the production of fine-particle iron oxides with a defined degree of oxidation and metallic iron for magnetic recording purposes.

Gerade bei solchen magnetischen Aufzeichnungsmaterialien kommt der Vorteil der erfindungsgemäßen Verwendung zum Tragen, da diese Produkte wegen ihrer Feinteiligkeit bei Temperaturbehandlungen leicht zu Versinterungen neigen, gleichzeitig sind die magnetischen Daten dieser qualitativ hochwertigen Produkte wesentlich von einem engen Teilchensprektrum bedingt.Especially with such magnetic recording materials, the advantage of the use according to the invention comes into play, since these products tend to sinter sintering due to their fine-particle nature during temperature treatments.

Aber auch die Gewinnung von Metallen, wie Wolfram, Kupfer oder Nickel, kann vorteilhaft im erfindungsgefäßen Drehrohrofen erfolgen. Weiter wird die Herstellung von Mischphasenpigmenten, Aktivkohle und keramischen Feststoffen in solchen öfen ermöglicht, um nur einige Beispiele anzuführen.However, metals such as tungsten, copper or nickel can also advantageously be obtained in the rotary tube furnace according to the invention. Furthermore, the production of mixed phase pigments, activated carbon and ceramic solids in such furnaces is made possible, to give just a few examples.

In den Abbildungen ist der erfindungsgemäße Drehrohrofen rein schematisch dargestellt und nachstehend näher erläutert. Im einzelnen zeigen

  • Fig. 1 einen Längsschnitt durch das Drehrohr,
  • Fig. 2 einen Querschnitt des Drehrohres.
In the figures, the rotary kiln according to the invention is shown purely schematically and explained in more detail below. Show in detail
  • 1 shows a longitudinal section through the rotary tube,
  • Fig. 2 shows a cross section of the rotary tube.

In Fig. 1 wird der Feststoff über eine Produktaufgabe 1 in das Drehrohr geführt. Er wird durch die zwischen äußerem Drehrohr 9 und innerem Zentralrohr 6 dicht eingebaute Wendel 5 entsprechend der Umdrehungszahl des Drehrohres in angezeigter Durchlaufrichtung weitergeführt. Das behandelte Produkt tritt bei 2 aus dem Drehrohr. Im Gegenstrom hierzu wird bei 3 das Reaktions-oder Prozeßgas dem Drehrohr zugeführt. Damit das Gas entsprechend der Wendelung spiralförmig dem Feststoff entgegenströmt, ist das innere Zentralrohr 6 an beiden Enden mit Verschlußstopfen 7 versehen. Bei 4 wird das Gas aus dem sich drehenden Reaktionsrohr abgeleitet.In Fig. 1, the solid is fed into the rotary tube via a product task 1. It is continued in the indicated direction of travel through the helix 5 tightly installed between the outer rotary tube 9 and the inner central tube 6 in accordance with the number of revolutions of the rotary tube. The treated product exits the rotary tube at 2. In countercurrent to this, the reaction or process gas is fed to the rotary tube at 3. In order that the gas flows counter to the solid according to the spiral, the inner central tube 6 is provided with sealing plugs 7 at both ends. At 4, the gas is discharged from the rotating reaction tube.

In Fig. 2 ist über dem Querschnitt gesehen schematisch der Anteil der Feststoffe zu erkennen, der als Schüttung auf den gleichmäßig über den inneren Umgang des äußeren Drehrohrofens 9 angebrachten Hubschaufeln 8 ruht. In 10 ist der Drehsinn des Gasstromes entgegen den von den Schaufeln 8 abfallenden Produktschleiern, und in 11 ist die Drehrichtung des Reaktionsrohres angezeigt.In FIG. 2, the portion of the solids can be seen schematically above the cross section, which rests as a bed on the lifting blades 8, which are evenly arranged over the inner handling of the outer rotary kiln 9. In FIG. 10 the direction of rotation of the gas flow is opposite to the product curtains falling off the blades 8, and in FIG. 11 the direction of rotation of the reaction tube is shown.

Die Dimensionierung der Einbauten ist abhängig von den vorgesehenen Mengenströmen, den erforderlichen Stoffverhältnissen und den produktspezifischen Eigenschaften der Reaktionspartner. Besonders gehen in die Auslegung Korngröße, Kornverteilung, Schüttwinkel und Dichte der Feststoffe sowie in geringerem Umfang Viskosität und Dichte der Gase ein, Kennzahlen, die auch in der Fließbettechnik eine wichtige Rolle spielen.The dimensioning of the internals depends on the intended volume flows, the required material ratios and the product-specific properties of the reactants. The grain size, particle size distribution, angle of repose and density of the solids, and to a lesser extent the viscosity and density of the gases, are key factors that also play an important role in fluid bed technology.

Durch die Festlegung von Drehrohrdurchmesser und -länge, Wendelsteigerung, Zentralrohrdurchmesser, Hubschaufelanzahl, -form, -höhe und -anstellung sind ausreichend Be-einflussungsmöglichkeiten für das Betriebsverhalten gegeben. Als veränderbare Parameter dienen Aufgabemenge, Tem- peraturprofil, Umdrehungszahl des Drehrohres, Gasmenge, Inertgasanteil und Ausgangstemperatur von Gas und Feststoff.By setting the rotary tube diameter and length, spiral increase, central pipe diameter, Hubschaufelanzahl, shape, height and -anstellung are sufficiently B e-einflussungsmöglichkeiten given for the operating behavior. As variable parameters are feed quantity, T em peraturprofil, speed of rotation of the rotating tube, gas quantity, inert gas and outlet temperature of gas and solid.

Die Drehzahl ist so zu wählen, daß das Material genügend oft angehoben wird. Bei zu geringer Umdrehung überwiegt das Ruhen der Schüttung auf den Hubschaufeln. Wenn bei normalen Drehzahlen die Verweilzeit bei gegebener Reaktorlänge für den vollständigen Umsatz nicht ausreicht, ist es sinnvoll, alternierend das Drehrohr in beiden Drehrichtungen zu betreiben, wobei die für die Produktdurchschleusung maßgebende Drehrichtung zeitlich überwiegt. Durch diese Maßnahme werden bei gleicher Drehzahl längere Verweilzeiten erhalten. Das Anstellen der Hubschaufeln wirkt sich bei dieser besonderen Verfahrensweise nicht mehr vorteilhaft aus.The speed should be selected so that the material is raised enough times. If the rotation is too low, the bed will rest on the lifting blades. If, at normal speeds, the dwell time for a given reactor length is not sufficient for complete conversion, it makes sense to operate the rotating tube alternately in both directions of rotation, with the direction of rotation that is decisive for product passage prevailing over time. This measure gives longer dwell times at the same speed. The setting of the lifting blades no longer has an advantageous effect in this special procedure.

Der Füllgrad des Drehrohres wird bevorzugterweise so eingestellt, daß kein überschießen des Produktes über die Hubschaufeln erfolgt.The degree of filling of the rotary tube is preferably set so that the product does not overshoot via the lifting blades.

Zur weiteren Erläuterung der erfindungsgemäßen Verwendung des Drehrohrofens dienen nachfolgend aufgeführte Beispiele, ohne daß darin eine Einschränkung der Erfindung zu sehen ist.The following examples serve to further explain the use of the rotary kiln according to the invention, without any restriction of the invention being seen therein.

Beispiel 1example 1

Herstellung von Magnetit aus Hämatit durch Reduktion mit Wasserstoff.Production of magnetite from hematite by reduction with hydrogen.

Durch Entwässerung von α-FeOOH (Goethit) gewonnenes, nadelförmiges oe -Fe203 (Hämatit) mit einer Korngröße von 0,5 bis 2 mm und einer spez. Oberfläche von 29 m2/g wird aus einem Vorratsbunker kontinuierlich über eine Bandwaage in den Drehrohrofen geleitet. Das indirekt beheizbare, gasdichte Drehrohr verfügt über eine in drei getrennt regelbaren Zonen aufgeteilte Heizstrecke von 2 m bei einem inneren Druchmesser von 30 cm. Die inneren Einbauten bestehen aus der geschlossenen Wendel mit 43 Windungen. In jeder Wendelkammer sind über den Umfang gleichmäßig verteilt 16 mit einem Winkel von 25° positiv angestellte Hibschaufeln angebracht. Die Höhe der Hubschaufeln beträgt 35 mm. Das Zentralrohr besitzt einen Durchmesser von 76 mm. Die Kanallänge errechnet sich zu ca. 25 m.Needle-shaped oe -Fe 2 0 3 (hematite) obtained by dewatering α-FeOOH (goethite) with a grain size of 0.5 to 2 mm and a spec. Surface of 29 m 2 / g is continuously fed from a storage bunker into the rotary kiln via a belt weigher. The indirectly heatable, gas-tight rotary tube has a heating section of 2 m divided into three separately controllable zones with an inner diameter of 30 cm. The internal internals consist of the closed helix with 43 turns. In each spiral chamber, 16 hib scoops are mounted, distributed evenly over the circumference, at an angle of 25 °. The height of the lifting blades is 35 mm. The central tube has a diameter of 76 mm. The channel length is approx. 25 m.

Mit einer eingestellten Drehzahl von 2 Upm wird eine Verweilzeit von etwa 20 min erhalten. Die Temperaturen werden von der Durchlaufrichtung der Feststoffe her gesehen in der ersten Zone auf 420°C und in der zweiten und dritten Zone auf 440°C gehalten. Bei einer Aufgabemenge an Hämatit von 24 kg/h beträgt der Füllgrad 11,5 %. Die im Gegenstrom zugeführte Wasserstoffmenge liegt bei 3 Nm3/h. Zusätzlich wird noch 1 Nm3/h Wasserdampf eingespeist. Zur Abdichtung von den Ofenköpfen dient die Aufgabe von 0,75 Nm3/h Stickstoff. Der Druckverlust im bewegten Drehrohr liegt bei 10 mm, im ruhenden bei 4 mm Wassersäule.With a set speed of 2 rpm, a dwell time of about 20 minutes is obtained. The temperatures are kept at 420 ° C in the first zone and at 440 ° C in the second and third zones from the direction of flow of the solids. With a hematite feed rate of 24 kg / h, the fill level is 11.5%. The quantity of hydrogen supplied in countercurrent is 3 Nm 3 / h. In addition, 1 Nm 3 / h of water vapor is fed in. The application of 0.75 Nm 3 / h of nitrogen serves to seal the furnace heads. The pressure loss in the moving rotary tube is 10 mm, in the stationary one 4 mm water column.

Am Ofenauslauf wurden kontinuierlich etwa 23 kg/h Magnetit mit einem FeO-Gehalt von 30 % erhalten. Nach der thermischen Behandlung des Produktes bei 100°C in einer Stickstoffatmosphäre mit 6,5 Vol.-% Sauerstoff erniedrigt sich der FeO-Gehalt auf 25 bis 27 %. Der nun stabilisierte nadelförmige Magnetit weist eine spez. Oberfläche von 28 m2/g auf. Die Ausrichtbarkeit (Rechteckigkeitsverhältnis) beträgt 0,90, gemessen in einem Magnetfeld von 3000 Oe. Die Koerzitivkraft liegt bei 450 Oe. Damit ist das erhaltene Produkt in der Anwendung als magnetisches Aufzeichnungsmaterial vorzüglich geeignet.About 23 kg / h of magnetite with an FeO content of 30% were continuously obtained at the furnace outlet. After the thermal treatment of the product at 100 ° C. in a nitrogen atmosphere with 6.5 vol.% Oxygen, the FeO content drops to 25 to 27%. The now stabilized acicular magnetite has a spec. Surface of 28 m 2 / g. The alignability (squareness ratio) is 0.90, measured in a magnetic field of 3000 Oe. The coercive force is 450 Oe. The product obtained is thus particularly suitable for use as a magnetic recording material.

Vergleichsversuche in einem Drehrohr gleicher Abmessungen, jedoch lediglich mit Wendeleisten als innere Einbauten, zeigten, daß bei gleicher Temperatureinstellung und bei gleichem Wasserstoffdurchsatz nur die halbe Gewichtsmenge Hämatit reduziert werden konnte. Zudem betrug die spezifische Oberfläche des erhaltenen stabilisierten Magnetits nur 24 m2/g bei einer niedrigeren Ausrichtbarkeit von 0,85.Comparative tests in a rotary tube of the same dimensions, but only with spiral strips as internal fittings, showed that with the same temperature setting and the same hydrogen throughput, only half the weight of hematite could be reduced. In addition, the specific surface area of the stabilized magnetite obtained was only 24 m 2 / g with a lower alignability of 0.85.

Beispiel 2Example 2

Herstellung von metallischen Eisenteilchen durch Reduktion von Goethit mittels Wasserstoff.Production of metallic iron particles by reduction of goethite using hydrogen.

In dem in Beispiel 1 beschriebenen Drehrohr wird α-FeOOH (Goethit) in einer Menge von 2 kg/h aufgegeben. Die Korngröße des zugeführten Materials liegt zwischen 0,5 und 2 mm. Die spez. Oberfläche beträgt 56 m2/g. Die Temperaturen des mit 4 % Neigung und 2 Upm sich drehenden Reaktionsrohres werden in den drei Heizzonen auf etwa 430°C eingestellt. Die im Gegenstrom zugeführte Wasserstoffmenge liegt bei 15 Nm3/h. Zusätzlich werden über die Ofenköpfe 2 Nm3/h Stickstoff eingeleitet. Man erhält stündlich 1,25 kg pyrophores Eisen mit einem Metallgehalt von 98,5 %. Die spez. Oberfläche des nadelförmigen Eisens beträgt 20 m2/g, die Koerzitivkraft 1100 Oe. Das Produkt ist besonders zur Einarbeitung in Magnetbänder geeignet..In the rotary tube described in Example 1, α-FeOOH (goethite) is added in an amount of 2 kg / h. The grain size of the material fed is between 0.5 and 2 mm. The spec. The surface is 56 m 2 / g. The temperatures of the reaction tube rotating at a 4% incline and 2 rpm are set to about 430 ° C. in the three heating zones. The amount of hydrogen supplied in counterflow is 15 Nm 3 / h. In addition, 2 N m 3 / h of nitrogen are introduced via the furnace heads. 1.25 kg of pyrophoric iron with a metal content of 98.5% are obtained per hour. The spec. The surface of the needle-shaped iron is 20 m 2 / g, the coercive force is 1100 Oe. The product is particularly suitable for incorporation into magnetic tapes.

Claims (9)

1. Drehrohrofen für die Durchführung von Gas-Feststoff-Reaktionen, bestehend aus einem indirekt beheizten, rotierenden und mit Auf- und Abgabevorrichtungen für Feststoffe und Gasein- und ableitungen versehenen Reaktionsrohr mit inneren Einbauten, dadurch gekennzeichnet, daß die Einbauten aus einem über die gesamte Ofenlänge verlaufenden, beidseitig geschlossenen Zentralrohr (6) und einer Wendelung (5), die ihrerseits sowohl mit dem Zentralrohr (6) und dem äußeren Drehrohr (9) dicht verbunden ist, bestehen.1. Rotary tube furnace for the implementation of gas-solid reactions, consisting of an indirectly heated, rotating and provided with feed and discharge devices for solids and gas inlet and outlet reaction tube with internal internals, characterized in that the internals from one over the entire Central tube (6) running on the length of the furnace and closed on both sides and a coil (5), which in turn is tightly connected to both the central tube (6) and the outer rotary tube (9). 2. Drehrohrofen gemäß Anspruch 1, dadurch gekennzeichnet, daß zusätzlich der innere Umfang des äußeren Drehrohres (9) mit Hubschaufeln <8) versehen ist.2. Rotary tube furnace according to claim 1, characterized in that in addition the inner circumference of the outer rotary tube (9) is provided with lifting blades <8). 3. Drehrohrofen gemäß Anspruch 2, dadurch gekennzeichnet, daß die Hubschaufeln positiv angestellt sind.3. Rotary tube furnace according to claim 2, characterized in that the lifting blades are turned positive. 4. Drehrohrofen gemäß einem der Ansprüche 2 oder 3, dadurch gekennzeichnet, daß die Hubschaufeln gleichmäßig verteilt sind.4. Rotary tube furnace according to one of claims 2 or 3, characterized in that the lifting blades are evenly distributed. 5. Drehrohrofen gemäß einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß das Reaktionsrohr gasdicht abgeschlossen ist.5. Rotary tube furnace according to one of claims 1 to 4, characterized in that the reaction tube is sealed gas-tight. 6. Verwendung des Drehrohrofens gemäß einem der Ansprüche 1 bis 5 zur Durchführung von Oxidations-, Reduktions-, Chlorierungs-, Abröst-, Aufschluß-, Katalyse-, Temper- oder Abkühlprozessen.6. The use of the rotary kiln according to one of claims 1 to 5 for carrying out oxidation, R eduktions-, chlorinating, Abröst-, pulping, catalysis, tempering or cooling processes. 7. Verwendung des Drehrohrofens gemäß einem der Ansprüche 1 bis 5 zur Herstellung von magnetischen Eisenoxidpigmenten.7. Use of the rotary kiln according to one of claims 1 to 5 for the production of magnetic iron oxide pigments. 8. Verwendung des Drehrohrofens gemäß einem der Ansprüche 1 bis 5 zur Herstellung von magnetischen Metallteilchen.8. Use of the rotary kiln according to one of claims 1 to 5 for the production of magnetic metal particles. 9. Verwendung des Drehrohrofens gemäß einem der Ansprüche 6 bis 8, dadurch gekennzeichnet, daß die Gase im Gegenstrom zu den Feststoffen geleitet werden.9. Use of the rotary kiln according to one of claims 6 to 8, characterized in that the gases are passed in countercurrent to the solids.
EP84108997A 1983-08-09 1984-07-30 Rotary drum furnace and its use Expired - Lifetime EP0135078B2 (en)

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US5718844A (en) * 1993-08-12 1998-02-17 H.C. Starck Gmbh & Co., Kg Cobalt/cobalt oxide powder
EP0651064A1 (en) * 1993-11-03 1995-05-03 IN.TEC. Italia - International Environment Technology S.r.l. A device and process for the pretreatement of electronic scrap
US5700425A (en) * 1993-11-03 1997-12-23 Celi; Antonio Maria Device for the pretreatment of electronic scrap
DE102009027635A1 (en) 2009-07-10 2011-01-13 Wacker Chemie Ag Process for the acetylation of lignocelluloses, hemicelluloses, celluloses with ketene
EP2287203A1 (en) 2009-07-10 2011-02-23 Wacker Chemie AG Process for the acetylation of lignocelluloses, hemicelluloses, celluloses with ketene

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EP0135078A3 (en) 1986-03-19
EP0135078B2 (en) 1991-10-09
DE3328709A1 (en) 1985-02-28
KR850001994A (en) 1985-04-10
JPH0526116B2 (en) 1993-04-15
KR920001099B1 (en) 1992-02-01
US4781580A (en) 1988-11-01
DE3471738D1 (en) 1988-07-07
US4629500A (en) 1986-12-16
EP0135078B1 (en) 1988-06-01
JPS6053775A (en) 1985-03-27

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