EP0007536B1 - Method and device for granulating a metal melt so as to produce powder - Google Patents

Method and device for granulating a metal melt so as to produce powder Download PDF

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Publication number
EP0007536B1
EP0007536B1 EP79102441A EP79102441A EP0007536B1 EP 0007536 B1 EP0007536 B1 EP 0007536B1 EP 79102441 A EP79102441 A EP 79102441A EP 79102441 A EP79102441 A EP 79102441A EP 0007536 B1 EP0007536 B1 EP 0007536B1
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EP
European Patent Office
Prior art keywords
gas
gas jet
jet
channel
tap stream
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Expired
Application number
EP79102441A
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German (de)
French (fr)
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EP0007536A1 (en
Inventor
Hans-Gunnar Larsson
Erik Westman
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CONCESSIONE DI LICENZA ESCLUSIVA;MINORA FORSCHUNGS
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ASEA AB
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
    • B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
    • B22F9/082—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
    • B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
    • B22F9/082—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid
    • B22F2009/088—Fluid nozzles, e.g. angle, distance

Definitions

  • the invention relates to a method for granulating a molten metal for the purpose of powder production according to the preamble of claim 1 and an apparatus for performing the method.
  • one or more vertical melt casting jets are hit from the side by a high-speed gas flow, through which the melt is broken up into fine droplets, which quickly solidify into a powder, so that after solidification, a fine structure of the material is maintained.
  • a nozzle arrangement for producing inorganic fibers by blowing which has a sickle-shaped outlet opening for a gas jet which strikes a jet of the molten material from the side.
  • the melt jet is broken up into droplets that draw a thread.
  • an auxiliary channel is arranged in the longitudinal direction in the nozzle, from which a second gas jet emerges essentially parallel to the sickle-shaped gas jet and hits the melt jet vertically from the side before it is caught by the sickle-shaped main jet .
  • the melt jet is divided into a number of thinner jets, which are then captured by the main gas stream.
  • a device for atomizing a metal melt in which the metal stream flowing vertically downwards flows through an annular nozzle which atomizes the metal jet by gas flowing out obliquely downwards.
  • the atomized jet emerging from the ring nozzle is then deflected in the horizontal direction by a horizontal gas stream emerging from a further nozzle in order to cool it over a cooling bed.
  • the invention has for its object to develop a method in addition to the device of the type mentioned for granulating a molten metal, by which considerably less energy is required for the granulation process than in the known method mentioned above and in which the device is limited to relatively small dimensions can.
  • a device for performing the method is according to the invention by the
  • the invention By means of the invention it is possible to granulate a molten metal with lower energy consumption than before by suitable formation of the gas jet.
  • the granulation can be carried out in an arrangement whose height is less than that of the known arrangements, so that the building accommodating the system does not have to be excessively high.
  • the invention enables a simpler gas circulation system and easier transport of the melt.
  • the plant according to the invention can in many cases already existing buildings are housed by ironworks.
  • the cost reduction for powder production achieved by the invention extends the area of application of hot isostatic pressing to simpler metal qualities. Alloys that are already well known can now be hot-pressed economically isostatically, which gives them better, more uniform quality than before.
  • the preferably V-shaped main gas jet and the auxiliary gas jet (second jet) have the same main direction, i. that is, they are directed to the same side of the melt pouring jet.
  • the second jet is preferably directed to the point of intersection between the pouring jet and the bottom of the channel-shaped jet or in such a way that it strikes the pouring jet immediately before it is hit by the gas stream of the channel-shaped jet.
  • a certain flattening or broadening of the melt pouring jet can occur. This flattening facilitates the granulation, so that a smaller proportion of coarse powder grains is obtained.
  • Gas at different pressures can be supplied to the nozzles that form the air jets.
  • the control of the path of the droplets formed and the resulting powder grains can be done by varying the pressure of the gas supplied to one or both nozzles, so that the relative strength of the jets is changed.
  • the granulating device contains a closed container which prevents air from entering.
  • a pouring box is attached to the container. From this, molten metal flows down through one or more tap holes into a granulation part of said container.
  • a nozzle which is shaped so that it forms a trough-shaped gas jet is fitted in the granulating part of the container in such a way that the gas jet cuts the pouring jet.
  • the mouth of the nozzle is as close as possible to the downward pouring jet.
  • the droplets that form and the powder grains that result from them are thrown onto a parabolic path and collected in a collecting part in the container that is adapted to this throwing parabola. This is provided with arrangements for removing the powder.
  • the device is provided with a gas supply system.
  • the system contains an auxiliary nozzle which generates the second gas stream directed onto the pouring jet and the bottom of the channel-shaped gas jet.
  • a ladle for collecting pouring stream melt can be arranged in the pelletizer under the pouring box. In this case, molten metal is caught in the event of any malfunctions and possibly during commissioning, so that the material that first passes through and may contain contaminants is not granulated.
  • the system can also contain a cooler and a line for the direct return of gas from the collecting part of the container to the granulating part only for the purpose of cooling the droplets and powder formed. Because of the improved design of the nozzles, the amount of gas in the granulation jets is not always sufficient to cool the droplets and the powder formed to the desired temperature.
  • the method according to the invention can also be used in those granulating devices in which several pouring jets emerge from the casting box at the same time.
  • a channel-shaped main gas jet and one or more auxiliary gas jets are generated for each pouring jet.
  • Fig. 1, 1 denotes a closed container with a granulating part 2 and a collecting part 3 for powder obtained with a shape adapted to the throwing parabola for drops formed and thus powder formed.
  • the container rests on a stand 4.
  • the pelletizing part 2 is provided with a pouring box 5 and with a pan 6 arranged below this pouring box 5 for collecting melt either in the event of malfunctions or possibly at the start of pouring when the melt is particularly heavily contaminated.
  • the lower wall 7 of the collecting part 3 is oblique. The angle of inclination is greater than the natural angle of fall of the powder.
  • the powder obtained is collected in a container 8.
  • the container 1 has a first inspection window 9 on one side wall of the pelletizing part directly in front of the pouring stream and two inspection windows 10 on the one side wall of the collecting part 3.
  • a removal opening for the passage of the used gas.
  • a cooler 11 is connected to this opening, by means of which the gas heated during the granulation process is cooled.
  • Part of the gas is over the Lines 12, 13, 14, 15 and 16 returned to the granulating part 2.
  • Another part of the gas is sucked through cleaning filters to a compressor, which supplies the pelletizing nozzles of the system with gas.
  • Fig. 2 shows the casting box 5 with molten metal.
  • a tap opening 17 through which a vertical pouring jet 18 is generated.
  • a main nozzle 19 and an auxiliary nozzle 20 are arranged to the side of the pouring jet 18.
  • the main nozzle 19 has a V-shaped opening 21 (FIG. 3), which generates a V-shaped gas jet 22 which shatters the pouring jet 18 into droplets which are rapidly cooled and form powder 23 which is thrown into the collecting part 3 of the container 1 in a parabolic throw path.
  • the acute angle of the V-shaped air jet can be between 15 "and 60". An acute angle is generally the most convenient. Because the gas jet 22 is V-shaped, two elliptical cut surfaces are obtained when the gas jet 22 hits the pouring jet 18. The gas jet thereby has a large effective width and thus a strong ability to break the pouring jet into small powder grains.
  • the nozzle 19 is provided with a groove 25 on its upper side.
  • the auxiliary nozzle 20 is directed so that a jet 26 blows down into this channel and into the channel of the gas jet 22 formed.
  • the auxiliary nozzle is also directed so that the auxiliary gas jet 26 hits the pouring jet 18.
  • the main nozzle 19, which produces the V-shaped gas jet 22, can be composed, for example, of a first part 19a with a supply duct 27 for gas and a second part 19b which is connected to the part 19a by means of bolts 28.
  • the parts 19a and 19b are designed such that a channel 31 with an outwardly increasing width is formed between the walls 29 and 30.
  • the nozzle thus has a so-called De Laval design, which means that the energy of the compressed gas is used to a high degree, as a result of which the gas jet has a very high speed and high energy content.
  • the part 19b in the nozzle 19 can be vertically displaceable relative to the part 19a , so that the width of the channel is adjustable.
  • the auxiliary nozzle 20 blows gas into the channel 25 at the nozzle mouth, so that a negative pressure created by the ejector effect is eliminated and the suction of melt into the nozzle mouth is prevented. This prevents the melt of the pouring jet 18 from coming into contact with the nozzle and settling on the nozzle, as a result of which the flow properties of the nozzle can be adversely affected or the nozzle can be completely clogged.
  • This protective effect of the jet 26 makes it possible to press the main nozzle closer to the pouring jet 18. As a result, the energy loss in the gas jet 22 is less until it meets the melt of the pouring jet 18. This means that the atomization effect is stronger, resulting in a higher quality powder that contains a smaller proportion of coarse grains that have to be sieved. A corresponding gas supply on the other sides of the nozzle can also be advantageous.
  • the gas jet 26 also has another important effect. By changing the pressure of the supplied gas and thus the speed and the amount of gas in the gas jet 26, the throwing parabola for the resulting powder can be influenced in such a way that the throwing path adapts best to the shape of the collecting part 3. In this way, the point in time at which the resulting powder reaches the ground can be influenced to a certain extent. This makes it easier to achieve sufficient cooling of the powder grains obtained, so that there is no sticking together.
  • the nozzles 19 and 20 can also be designed as a unit, as shown in FIG.
  • the nozzle 20 is formed from a channel in one part 19a of the main nozzle 19.
  • FIG. 7 shows a nozzle 19 with two auxiliary nozzles 20a and 20b, the orifices of which are arranged close to the uppermost parts of the V-shaped nozzle opening 21.
  • the angle ⁇ (FIG. 2) between the main nozzle 19 and the pouring jet 18 can vary within wide limits.
  • the angle a can be in the range of 45 ° -135 °, preferably it is between 60 and 100 ".
  • the design of the gas jet enables the pouring jet to be atomized with a smaller amount of gas than in known designs. This achieves a considerable reduction in the energy requirement for the compression of the gas, as well as a considerable reduction in the required cleaning devices for the gas which is removed from the container 1 for the purpose of cleaning.
  • the amount of gas required to solidify the melt droplets into solid powder is greater than that consumed by the nozzles 19 and 20. A certain part of the amount of gas which is removed from the collecting part 3 by the cooler 11 is returned to the granulating part 2 in the container 1 via the lines 12, 13, 14, 15 and 16 without cleaning.
  • the nozzle 19 is mounted in the cooling air flow.
  • a suitable design for their cross-section can achieve a significant driving force for the cooling air flow. This ejector effect alone or in combination with a fan can cause the gas circulation required to cool the drops and the powder.
  • the invention makes it possible to reduce the height of the granulating plant. This is achieved by making the gas flow channel-shaped so that a pouring jet can be broken up directly into droplets which form a powder of a suitable grain size without the droplet jet from crossing second gas jet is cut.
  • Known effective pelletizers using gas as the pelletizer require cooling towers that are more than six meters high. This requires expensive high-rise buildings and expensive transportation means for the vertical transportation of raw material for melting furnaces or for molten metal.
  • the granulating plant according to the invention can be accommodated in containers that are only three meters high. As a result, you can achieve great savings in new buildings. Above all, the plant can be accommodated in existing ironworks buildings, and you can use the smelting plants and transport aids available in these. This means that the changeover to powder production according to the invention results in relatively low costs.

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  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)
  • Glanulating (AREA)

Description

Die Erfindung betrifft ein Verfahren zur Granulierung einer Metallschmelze zwecks Pulverherstellung gemäß dem Oberbegriff des Anspruchs 1 sowie eine Vorrichtung zur Durchführung des Verfahrens. Bei einem solchen Verfahren werden ein oder gleichzeitig mehrere vertikale Schmelzengießstrahlen von der Seite her durch je einen Gasstrom hoher Geschwindigkeit getroffen, durch welchen die Schmelze zu feinen Tröpfchen zertrümmert wird, welche schnell zu einem Pulver erstarren, so daß nach der Erstarrung eine feine Struktur des Materials beibehalten wird.The invention relates to a method for granulating a molten metal for the purpose of powder production according to the preamble of claim 1 and an apparatus for performing the method. In such a method, one or more vertical melt casting jets are hit from the side by a high-speed gas flow, through which the melt is broken up into fine droplets, which quickly solidify into a powder, so that after solidification, a fine structure of the material is maintained.

Das Verfahren und die Vorrichtung nach der Erfindung können für alle Arten von metallischem Material verwendet werden; sie sind jedoch in erster Linie bestimmt für die Herstellung von Stahlpulver mit einem hohen Gehalt an Legierungszusätzen, z. B. Schnellstrahl, oder Pulver aus Superlegierungen. Es ist schwierig, solche Legierungen durch herkömmliche Gießverfahren herzustellen, weil die langsame Erstarrung der Schmelze, insbesondere bei großen Gußstücken eine Ausscheidung von Legierungszusätzen, Seigerungsbildung, schlechtere Struktur durch Kornzuwachs usw. zur Folge hat. Durch die Granulation zu Pulver in einem Gasstrom kann man dagegen eine so schnelle Abkühlung der gebildeten Tröpfchen erreichen, daß der Temperaturbereich in dem ein Kornzuwachs und andere ungünstige Strukturveränderungen stattfinden, schnell passiert wird. Durch isostatisches Heizpressen des gewonnenen Pulvers ist es dann möglich, Körper herzustellen, in denen die günstige Struktur des Pulvers beibehalten wird. Wenn möglich, sollte das Pulver die folgenden Eigenschaften haben:

  • a) Einen niedrigen Gehalt an Verunreinigungen, vor allem an Sauerstoff. Es muß reines Gas mit einem niedrigen Sauerstoffgehalt oder einem niedrigen Gehalt an anderen schädlichen Stoffen verwendet werden. Zur Herstellung von Schnellstahlpulver beziehungsweise Superlegierungspulver wird reiner Stickstoff oder reines Edelgas verwendet.
  • b) Eine sphärische Kornform im wesentlichen ohne Blasen oder Hohlräume.
  • c) Eine im Hinblick auf das Heißpressen zweckmäßige Korngrößenverteilung.
  • d) Eine feine Mikrostruktur.
The method and the device according to the invention can be used for all types of metallic material; however, they are primarily intended for the production of steel powder with a high content of alloy additives, e.g. B. quick jet, or powder from super alloys. It is difficult to produce such alloys by conventional casting methods because the slow solidification of the melt, especially in the case of large castings, results in the addition of alloy additives, segregation, poorer structure due to grain growth, etc. By granulation into powder in a gas stream, on the other hand, the droplets formed can be cooled so rapidly that the temperature range in which grain growth and other unfavorable structural changes take place is passed quickly. It is then possible to produce bodies in which the favorable structure of the powder is maintained by isostatic hot pressing of the powder obtained. If possible, the powder should have the following properties:
  • a) A low level of impurities, especially oxygen. Pure gas with a low oxygen content or a low content of other harmful substances must be used. Pure nitrogen or pure noble gas is used to produce high-speed steel powder or superalloy powder.
  • b) A spherical grain shape essentially without bubbles or voids.
  • c) An appropriate grain size distribution with regard to hot pressing.
  • d) A fine microstructure.

Die Granulation einer Metallschmelze erfordert viel Energie und große Investitionen. Die hohen Kosten für die Herstellung von Pulver haben das isostatische Heizpressen von Pulver zur Herstellung von Körpern bisher auf teure Legierungen beschränkt, die nur unter Schwierigkeiten oder gar nicht nach konventionellen Schmelzverfahren hergestellt werden können.The granulation of a molten metal requires a lot of energy and large investments. The high cost of producing powder has so far limited the isostatic hot pressing of powder for the production of bodies to expensive alloys, which can only be produced with difficulty or not at all by conventional melting processes.

Aus der DE-B-1 816 268 ist eine Düsenanordnung zur Herstellung anorganischer Fasern durch Zerblasen bekannt, die eine sichelförmige Austrittsöffnung für einen Gasstrahl hat, der von der Seite her auf einen Strahl des geschmolzenen Materials trifft. Der Schmelzenstrahl wird dadurch in Tröpfchen zerteilt, die einen Faden nach sich ziehen. Um die Anzahl der sich bildenden Fäden zu vergrößern, ist in der Düse in Längsrichtung ein Hilfskanal angeordnet, aus dem ein zweiter Gasstrahl im wesentlichen parallel zu dem sichelförmigen Gasstrahl austritt und den Schmelzenstrahl senkrecht von der Seite trifft, bevor dieser von dem sichelförmigen Hauptstrahl erfaßt wird. Dadurch wird der Schmelzenstrahl in eine Anzahl dünnerer Strahlen aufgeteilt, die dann von dem Hauptgasstrom erfaßt werden.From DE-B-1 816 268 a nozzle arrangement for producing inorganic fibers by blowing is known, which has a sickle-shaped outlet opening for a gas jet which strikes a jet of the molten material from the side. As a result, the melt jet is broken up into droplets that draw a thread. In order to increase the number of threads forming, an auxiliary channel is arranged in the longitudinal direction in the nozzle, from which a second gas jet emerges essentially parallel to the sickle-shaped gas jet and hits the melt jet vertically from the side before it is caught by the sickle-shaped main jet . As a result, the melt jet is divided into a number of thinner jets, which are then captured by the main gas stream.

Aus Fig. 2 der DE-B-2 158 144 ist eine Vorrichtung zum Zerstäuben einer Metallschmelze bekannt, bei welcher der senkrecht nach unten fließende Metallstrom durch eine Ringdüse strömt, die den Metallstrahl durch schräg nach unten ausströmendes Gas zerstäubt. Anschließend wird der aus der Ringdüse austretende zerstäubte Strahl durch einen aus einer weiteren Düse austretenden horizontalen Gasstrom in horizontaler Richtung umgelenkt, um ihn über einem Kühlbett zu kühlen.From FIG. 2 of DE-B-2 158 144 a device for atomizing a metal melt is known, in which the metal stream flowing vertically downwards flows through an annular nozzle which atomizes the metal jet by gas flowing out obliquely downwards. The atomized jet emerging from the ring nozzle is then deflected in the horizontal direction by a horizontal gas stream emerging from a further nozzle in order to cool it over a cooling bed.

Der Erfindung liegt die Aufgabe zugrunde, ein Verfahren nebst Vorrichtung der eingangs genannten Art zur Granulierung einer Metallschmelze zu entwickeln, durch welches für den Granuliervorgang erheblich weniger Energie als bei dem eingangs genannten bekannten Verfahren erforderlich ist und bei dem die Vorrichtung auf relativ kleine Abmessungen beschränkt werden kann.The invention has for its object to develop a method in addition to the device of the type mentioned for granulating a molten metal, by which considerably less energy is required for the granulation process than in the known method mentioned above and in which the device is limited to relatively small dimensions can.

Zur Lösung dieser Aufgabe wird ein Verfahren nach dem Oberbegriff des Anspruchs 1 vorgeschlagen, welches die im kennzeichnenden Teil des Anspruchs 1 genannten Merkmale hat.To achieve this object, a method is proposed according to the preamble of claim 1, which has the features mentioned in the characterizing part of claim 1.

Vorteilhafte Weiterbildungen dieses Verfahrens sind in den Unteransprüchen 2 bis 8 genannt.Advantageous developments of this method are mentioned in subclaims 2 to 8.

Eine Vorrichtung zur Durchführung des Verfahrens ist gemäß der Erfindung durch die imA device for performing the method is according to the invention by the

Anspruch 9 genannten Merkmale gekennzeichnet.Characterized mentioned features 9.

Vorteilhafte Weiterbildungen dieser Vorrichtung sind in den Ansprüchen 10 bis 14 genannt.Advantageous developments of this device are mentioned in claims 10 to 14.

Durch die Erfindung gelingt es, durch geeignete Ausbildung des Gasstrahles eine Metallschmelze mit geringerem Energieverbrauch als bisher zu granulieren. Die Granulation kann in einer Anordnung ausgeführt werden, deren Höhe geringer ist, als die der bekannten Anordnungen, so daß auch das die Anlage aufnehmende Gebäude nicht übermäßig hoch sein muß. Die Erfindung ermöglicht ein einfacheres Gaszirkulationssystem und einen einfacheren Transport der Schmelze. Die Anlage nach der Erfindung kann in vielen Fällen in bereits vorhandene Gebäude von Eisenwerken untergebracht werden. Die durch die Erfindung erzielte Kostensenkung für die Pulverherstellung erweitert den Anwendungsbereich des isostatischen Heißpressens auf einfachere Metallqualitäten. Bereits allgemein bekannte Legierungen können nunmehr wirtschaftlich isostatisch heißgepreßt werden, wodurch sie eine bessere, gleichmäßigere Qualität als bisher erhalten.By means of the invention it is possible to granulate a molten metal with lower energy consumption than before by suitable formation of the gas jet. The granulation can be carried out in an arrangement whose height is less than that of the known arrangements, so that the building accommodating the system does not have to be excessively high. The invention enables a simpler gas circulation system and easier transport of the melt. The plant according to the invention can in many cases already existing buildings are housed by ironworks. The cost reduction for powder production achieved by the invention extends the area of application of hot isostatic pressing to simpler metal qualities. Alloys that are already well known can now be hot-pressed economically isostatically, which gives them better, more uniform quality than before.

Der vorzugsweise V-förmige Hauptgasstrahl und der Hilfsgasstrahl (zweite Strahl) haben dieselbe Hauptrichtung, d. h., sie sind auf dieselbe Seite des Schmelzengießstrahls gerichtet. Der zweite Strahl ist vorzugsweise auf den Schnittpunkt zwischen dem Gießstrahl und dem Boden des rinnenförmigen Strahls oder so gerichtet, daß er den Gießstrahl trifft unmittelbar bevor dieser vom Gasstrom des rinnenförmigen Strahls getroffen wird. Dabei kann eine gewisse Abplattung oder Verbreiterung des Schmelzengießstrahls auftreten. Diese Abplattung erleichtert die Granulierung, so daß man einen kleineren Anteil an groben Pulverkörnern erhält. Den Düsen, welche die Luftstrahlen bilden, kann Gas mit verschiedenem Druck zugeführt werden. Die Steuerung der Wurfbahn der gebildeten Tröpfchen und der entstehenden Pulverkörner kann durch Variation des Druckes des der einen oder beiden Düsen zugeführten Gases geschehen, so daß die relative Stärke der Strahlen verändert wird..The preferably V-shaped main gas jet and the auxiliary gas jet (second jet) have the same main direction, i. that is, they are directed to the same side of the melt pouring jet. The second jet is preferably directed to the point of intersection between the pouring jet and the bottom of the channel-shaped jet or in such a way that it strikes the pouring jet immediately before it is hit by the gas stream of the channel-shaped jet. A certain flattening or broadening of the melt pouring jet can occur. This flattening facilitates the granulation, so that a smaller proportion of coarse powder grains is obtained. Gas at different pressures can be supplied to the nozzles that form the air jets. The control of the path of the droplets formed and the resulting powder grains can be done by varying the pressure of the gas supplied to one or both nozzles, so that the relative strength of the jets is changed.

Die erfindungsgemäße Vorrichtung zum Granulieren enthält einen geschlossenen Behälter, der einen Luftzutritt verhindert. Auf dem Behälter ist ein Gießkasten angebracht. Aus diesem fließt geschmolzenes Metall durch ein oder mehrere Abstichlöcher nach unten in einen Granulationsteil des genannten Behälters. Eine Düse, die so geformt ist, daß sie einen rinnenförmigen Gasstrahl bildet, ist im Granulierteil des Behälters derart angebracht, daß der Gasstrahl den Gießstrahl schneidet. Die Mündung der Düse ist so nahe wie möglich an dem nach unten gerichteten Gießstrahl angeordnet. Die sich bildenden Tröpfchen und die aus ihnen entstehenden Pulverkörner werden auf eine parabelförmige Bahn geworfen und in einem dieser Wurfparabel angepaßten Auffangteil im Behälter gesammelt. Dieser ist mit Anordnungen zur Entnahme des Pulvers versehen. Ferner ist die Vorrichtung mit einer Gasversorgungsanlage versehen. Diese enthält Gasreiniger und Kühler für zirkulierendes Gas, das komprimiert und den Granulationsdüsen erneut zugeführt wird. Außer einer Hauptdüse, die den rinnenförmigen Gasstrahl erzeugt, enthält die Anlage eine Hilfsdüse, die den zweiten, auf den Gießstrahl und den Boden des rinnenförmigen Gasstrahls gerichteten Gasstrom erzeugt. Es können mehrere parallele Hauptdüsen vorhanden sein. Eine Gießpfanne zum Auffangen von Gießstrahlschmelze kann im Granulierteil unter dem Gießkasten angeordnet sein. Hierin wird Metallschmelze bei eventuellen Betriebsstörungen und eventuell bei Inbetriebnahme aufgefangen, damit das zuerst passierende Material, das Verunreinigungen enthalten kann, nicht granuliert wird.The granulating device according to the invention contains a closed container which prevents air from entering. A pouring box is attached to the container. From this, molten metal flows down through one or more tap holes into a granulation part of said container. A nozzle which is shaped so that it forms a trough-shaped gas jet is fitted in the granulating part of the container in such a way that the gas jet cuts the pouring jet. The mouth of the nozzle is as close as possible to the downward pouring jet. The droplets that form and the powder grains that result from them are thrown onto a parabolic path and collected in a collecting part in the container that is adapted to this throwing parabola. This is provided with arrangements for removing the powder. Furthermore, the device is provided with a gas supply system. This contains gas cleaners and coolers for circulating gas, which is compressed and fed back to the granulation nozzles. In addition to a main nozzle which generates the channel-shaped gas jet, the system contains an auxiliary nozzle which generates the second gas stream directed onto the pouring jet and the bottom of the channel-shaped gas jet. There can be several parallel main nozzles. A ladle for collecting pouring stream melt can be arranged in the pelletizer under the pouring box. In this case, molten metal is caught in the event of any malfunctions and possibly during commissioning, so that the material that first passes through and may contain contaminants is not granulated.

Die Anlage kann auch einen Kühler und eine Leitung zur direkten Rückführung von Gas vom Auffangteil des Behälters zum Granulierteil enthalten lediglich zwecks Kühlung der gebildeten Tröpfchen und des Pulvers. Durch die verbesserte Ausführung der Düsen reicht nämlich die Gasmenge in den Granulierstrahlen nicht immer aus, um die gebildeten Tröpfchen und das Pulver auf die gewünschte Temperatur abzukühlen.The system can also contain a cooler and a line for the direct return of gas from the collecting part of the container to the granulating part only for the purpose of cooling the droplets and powder formed. Because of the improved design of the nozzles, the amount of gas in the granulation jets is not always sufficient to cool the droplets and the powder formed to the desired temperature.

Es versteht sich, daß das Verfahren nach der Erfindung auch bei solchen Granuliervorrichtungen anwendbar ist, bei denen aus dem Gießkasten gleichzeitig mehrere Gießstrahlen austreten. In diesem Falle werden für jeden Gießstrahl ein rinnenförmiger Hauptgasstrahl und ein oder mehrere Hilfsgasstrahlen erzeugt.It goes without saying that the method according to the invention can also be used in those granulating devices in which several pouring jets emerge from the casting box at the same time. In this case, a channel-shaped main gas jet and one or more auxiliary gas jets are generated for each pouring jet.

Anhand der in den Figuren gezeigten Ausführungsbeispiele von Granulieranordnungen nach der Erfindung soll die Erfindung näher erläutert werden. Es zeigt

  • Fig. eine Seitenansicht einer Granuf*ervor- richtung nach der Erfindung,
  • Fig. 2 schematisch die Pfanne und die Anbringung der Düsen im Verhältnis zum Gießstrahl,
  • Fig. 3 einen Schnitt längs der Linie A-A in Fig. 2 nahe der Gasdüsen, welche die Gasstrahlen zur Verstäubung des Gießstrahles erzeugen,
  • Fig. 4 einen Schnitt durch die Hauptdüse längs der Linie C-C in Fig. 3,
  • Fig. 5 einen Schnitt durch eine andere Ausführungsform der Düsenanordnung,
  • Fig.6 einen Schnitt durch den V-förmigen Gasstrahl längs der Linie B-B in Fig. 2,
  • Fig.7 schematisch eine Düsenanordnung mit zwei Hilfsdüsen.
The invention will be explained in more detail with reference to the exemplary embodiments of pelletizing arrangements according to the invention shown in the figures. It shows
  • 1 shows a side view of a granuf * device according to the invention,
  • 2 shows schematically the pan and the attachment of the nozzles in relation to the pouring jet,
  • 3 shows a section along the line AA in FIG. 2 near the gas nozzles which generate the gas jets for dusting the pouring jet,
  • 4 shows a section through the main nozzle along the line CC in FIG. 3,
  • 5 shows a section through another embodiment of the nozzle arrangement,
  • 6 shows a section through the V-shaped gas jet along the line BB in FIG. 2,
  • 7 schematically shows a nozzle arrangement with two auxiliary nozzles.

In Fig. 1 bezeichnet 1 einen geschlossenen Behälter mit einem Granulierteil 2 und einem Auffangteil 3 für gewonnenes Pulver mit einer der Wurfparabel für gebildete Tropfen und somit gebildetem Pulver angepaßten Form. Der Behälter ruht auf einem Stativ 4. Der Granulierteil 2 ist mit einem Gießkasten 5 und mit einer unter diesem Gießkasten 5 angebrachten Pfanne 6 zum Auffangen von Schmelze entweder bei Betriebsstörungen oder eventuell zu Beginn des Abgießens, wenn die Schmelze besonders stark verunreinigt ist, versehen. Die untere Wand 7 des Auffangteils 3 ist schräg. Der Neigungswinkel ist größer als der natürliche Fallwinkel des Pulvers. Das gewonnene Pulver wird in einem Behälter 8 aufgefangen. Der Behälter 1 hat ein erstes Inspektionsfenster9 an der einen Seitenwand des Granulierteils direkt vor dem Gießstrahl und zwei Inspektionsfenster 10 an der einen Seitenwand des Auffangteils 3.- In der oberen Wand des Auffangteils befindet sich eine Entnahmeöffnung zur Fortleitung des verbrauchten Gases. An diese Öffnung ist ein Kühler 11 angeschlossen: durch den das während des Granuliervorgänges erhitzte Gas gekühlt wird. Ein Teil des Gases wird über die Leitungen 12, 13, 14, 15 und 16 zum Granulierteil 2 zurückgeführt. Ein anderer Teil des Gases wird über Reinigungsfilter zu einem Kompressor gesaugt, der die Granulierdüsen der Anlage mit Gas versorgt.In Fig. 1, 1 denotes a closed container with a granulating part 2 and a collecting part 3 for powder obtained with a shape adapted to the throwing parabola for drops formed and thus powder formed. The container rests on a stand 4. The pelletizing part 2 is provided with a pouring box 5 and with a pan 6 arranged below this pouring box 5 for collecting melt either in the event of malfunctions or possibly at the start of pouring when the melt is particularly heavily contaminated. The lower wall 7 of the collecting part 3 is oblique. The angle of inclination is greater than the natural angle of fall of the powder. The powder obtained is collected in a container 8. The container 1 has a first inspection window 9 on one side wall of the pelletizing part directly in front of the pouring stream and two inspection windows 10 on the one side wall of the collecting part 3. In the upper wall of the collecting part there is a removal opening for the passage of the used gas. A cooler 11 is connected to this opening, by means of which the gas heated during the granulation process is cooled. Part of the gas is over the Lines 12, 13, 14, 15 and 16 returned to the granulating part 2. Another part of the gas is sucked through cleaning filters to a compressor, which supplies the pelletizing nozzles of the system with gas.

Fig. 2 zeigt den Gießkasten 5 mit geschmolzenem Metall. Im Boden des Gießkastens befindet sich eine Abstichöffnung 17, über die ein vertikaler Gießstrahl 18 erzeugt wird.Fig. 2 shows the casting box 5 with molten metal. In the bottom of the pouring box there is a tap opening 17 through which a vertical pouring jet 18 is generated.

Seitlich des Gießstrahles 18 sind eine Hauptdüse 19 und eine Hilfsdüse 20 angeordnet Die Hauptdüse 19 hat eine V-förmige Öffnung 21 (Fig.3), die einen V-förmigen Gasstrahl 22 erzeugt, der den Gießstrahl 18 in Tröpfchen zertrümmert, die schnell abgekühlt werden und Pulver 23 bilden, das in einer parabelförmigen Wurfbahn in den Auffangteil 3 des Behälters 1 geworfen wird. Der spitze Winkel des V-förmigen Luftstrahls kann zwischen 15" und 60" betragen. Ein spitzer Winkel ist im allgemeinen am günstigsten. Dadurch, daß der Gasstrahl 22 V-förmig ist, erhält man zwei ellipsenförmige Schnittflächen, wenn der Gasstrahl 22 den Gießstrahl 18 trifft. Der Gasstrahl bekommt dabei eine große effektive Breite und damit ein starkes Vermögen, den Gießstrahl zu kleinen Pulverkörnern zu zertrümmern Die Düse 19 ist an ihrer oberen Seite mit einer Rinne 25 versehen. Die Hilfsdüse 20 ist so gerichtet, daß ein Strahl 26 in diese Rinne und in die Rinne des gebildeten Gasstrahls 22 hinunterbläst. Die Hilfsdüse ist auch so gerichtet, daß der Hilfsgasstrahl 26 den Gießstrahl 18 trifft. Die Hauptdüse 19, die den V-förmigen Gasstrahl 22 ergibt, kann beispielsweise zusammengesetzt sein aus einem ersten Teil 19a mit einem Zuleitungskanal 27 für Gas und einem zweiten Teil 19b, welches mittels Bolzen 28 mit dem Teil 19a verbunden ist. Die Teile 19a und 19b sind so ausgebildet, daß zwischen den Wänden 29 und 30 ein Kanal 31 mit nach außen zunehmender Weite gebildet wird. Die Düse hat also eine sogenannte De Laval-Ausführung, was bedeutet, daß die Energie des Druckgases hoch ausgenutzt wird, wodurch der Gasstrahl eine sehr hohe Geschwindigkeit und einen hohen Energiegehalt bekommt Der Teil 19b in der Düse 19 kann gegenüber dem Teil 19a vertikal verschiebbar sein, so daß die Weite des Kanals verstellbar ist. Die Hilfsdüse 20 bläst Gas in die Rinne 25 an der Düsenmündung, so daß ein durch Ejektorwirkung entstandener Unterdruck beseitigt und damit das Einsaugen von Schmelze in die Düsenmündung verhindert wird. Hierdurch wird verhindert, daß die Schmelze des Gießstrahls 18 mit der Düse in Kontakt kommt und sich an der Düse absetzt, wodurch die Strömungseigenschaften der Düse ungünstig beeinflußt werden können oder die Düse völlig zugesetzt werden kann. Durch diese Schutzvlirkung des Strahls 26 ist es möglich, die Hauptdüse näher an den Gießstrahl 18 heranzudrücken. Dadurch ist der Energieverlust im Gasstrahl 22 bis zu seinem Zusammentreffen mit der Schmelze des Gießstrahls 18 geringer. Dies bedeutet, daß die Zerstäubungswirkung stärker ist, wodurch man ein hochwertigeres Pulver erhält, das einen geringeren Anteil an groben Körnern enthält, die abgesiebt werden müssen. Eine entsprechende Gaszufuhr an den übrigen Seiten der Düse kann auch vorteilhaft sein. Der Gasstrahl 26 hat auch eine andere wichtige Wirkung. Durch Änderung des Druckes des zugeführten Gases und damit der Geschwindigkeit und der Gasmenge des Gasstrahls 26 kann die Wurfparabel für das entstehende Pulver derart beeinflußt werden, daß sich die Wurfbahn der Form des Auffangteils 3 am besten anpaßt. Hierdurch kann der Zeitpunkt, zu dem entstandenes Pulver den Boden erreicht, in gewissem Maße beeinflußt werden. Dadurch ist es leichter, eine genügende Abkühlung der gewonnenen Pulverkörner zu erzielen, so daß kein Zusammenkleben auftritt.A main nozzle 19 and an auxiliary nozzle 20 are arranged to the side of the pouring jet 18. The main nozzle 19 has a V-shaped opening 21 (FIG. 3), which generates a V-shaped gas jet 22 which shatters the pouring jet 18 into droplets which are rapidly cooled and form powder 23 which is thrown into the collecting part 3 of the container 1 in a parabolic throw path. The acute angle of the V-shaped air jet can be between 15 "and 60". An acute angle is generally the most convenient. Because the gas jet 22 is V-shaped, two elliptical cut surfaces are obtained when the gas jet 22 hits the pouring jet 18. The gas jet thereby has a large effective width and thus a strong ability to break the pouring jet into small powder grains. The nozzle 19 is provided with a groove 25 on its upper side. The auxiliary nozzle 20 is directed so that a jet 26 blows down into this channel and into the channel of the gas jet 22 formed. The auxiliary nozzle is also directed so that the auxiliary gas jet 26 hits the pouring jet 18. The main nozzle 19, which produces the V-shaped gas jet 22, can be composed, for example, of a first part 19a with a supply duct 27 for gas and a second part 19b which is connected to the part 19a by means of bolts 28. The parts 19a and 19b are designed such that a channel 31 with an outwardly increasing width is formed between the walls 29 and 30. The nozzle thus has a so-called De Laval design, which means that the energy of the compressed gas is used to a high degree, as a result of which the gas jet has a very high speed and high energy content. The part 19b in the nozzle 19 can be vertically displaceable relative to the part 19a , so that the width of the channel is adjustable. The auxiliary nozzle 20 blows gas into the channel 25 at the nozzle mouth, so that a negative pressure created by the ejector effect is eliminated and the suction of melt into the nozzle mouth is prevented. This prevents the melt of the pouring jet 18 from coming into contact with the nozzle and settling on the nozzle, as a result of which the flow properties of the nozzle can be adversely affected or the nozzle can be completely clogged. This protective effect of the jet 26 makes it possible to press the main nozzle closer to the pouring jet 18. As a result, the energy loss in the gas jet 22 is less until it meets the melt of the pouring jet 18. This means that the atomization effect is stronger, resulting in a higher quality powder that contains a smaller proportion of coarse grains that have to be sieved. A corresponding gas supply on the other sides of the nozzle can also be advantageous. The gas jet 26 also has another important effect. By changing the pressure of the supplied gas and thus the speed and the amount of gas in the gas jet 26, the throwing parabola for the resulting powder can be influenced in such a way that the throwing path adapts best to the shape of the collecting part 3. In this way, the point in time at which the resulting powder reaches the ground can be influenced to a certain extent. This makes it easier to achieve sufficient cooling of the powder grains obtained, so that there is no sticking together.

Die Düsen 19 und 20 können auch als eine Einheit ausgebildet sein, wie in Fig.5 gezeigt. Die Düse 20 wird dabei aus einem Kanal in dem einen Teil 19a der Hauptdüse 19 gebildet.The nozzles 19 and 20 can also be designed as a unit, as shown in FIG. The nozzle 20 is formed from a channel in one part 19a of the main nozzle 19.

Aus Fig.6 geht deutlich hervor, daß ein V-förmiger Gasstrahl eine sehr große wirksame Breite bekommt.From Figure 6 it is clear that a V-shaped gas jet has a very large effective width.

Fig. 7 zeigt eine Düse 19 mit zwei Hilfsdüsen 20a und 20b, deren Mündungen nahe an den obersten Teilen der V-förmigen Düsenöffnung 21 angebracht sind.FIG. 7 shows a nozzle 19 with two auxiliary nozzles 20a and 20b, the orifices of which are arranged close to the uppermost parts of the V-shaped nozzle opening 21.

Der Winkel α (Fig. 2) zwischen der Hauptdüse 19 und dem Gießstrahl 18 kann innerhalb weiter Grenzen variieren. Der Winkel a kann im Bereich von 45°-135° liegen, vorzugsweise liegt er zwischen 60 und 100".The angle α (FIG. 2) between the main nozzle 19 and the pouring jet 18 can vary within wide limits. The angle a can be in the range of 45 ° -135 °, preferably it is between 60 and 100 ".

Die Ausführung des Gasstrahls ermöglicht ein Zerstäuben des Gießstrahls mit einer kleineren Gasmenge als bei bekannten Ausführungen. Hierdurch wird eine erhebliche Verminderung des Energiebedarfs für die Komprimierung des Gases erreicht, sowie eine erhebliche Verkleinerung der erforderlichen Reinigungseinrichtungen für das Gas, welches dem Behälter 1 zwecks Reinigung entnommen wird. Die zur Herbeiführung der Erstarrung der Schmelzentröpfchen zu festem Pulver erforderliche Gasmenge ist größer als die , die von den Düsen 19 und 20 verbraucht wird. Ein gewisser Teil der Gasmenge, die durch den Kühler 11 aus dem Auffangteil 3 entnommen wird, wird ohne Reinigung über die Leitungen 12, 13, 14, 15 und 16 zum Granulierteil 2 im Behälter 1 zurückgeführt. Wie aus Fig. 1 hervorgeht, ist die Düse 19 im Kühlluftstrom angebracht. Durch geeignete Ausführung ihres Querschnitts kann man eine erhebliche Antriebskraft für den Kühlluftstrom erreichen. Diese Ejektorwirkung allein oder in Kombination mit einem Lüfter kann die zur Kühlung der Tropfen und des Pulvers erforderliche Gaszirkulation bewirken.The design of the gas jet enables the pouring jet to be atomized with a smaller amount of gas than in known designs. This achieves a considerable reduction in the energy requirement for the compression of the gas, as well as a considerable reduction in the required cleaning devices for the gas which is removed from the container 1 for the purpose of cleaning. The amount of gas required to solidify the melt droplets into solid powder is greater than that consumed by the nozzles 19 and 20. A certain part of the amount of gas which is removed from the collecting part 3 by the cooler 11 is returned to the granulating part 2 in the container 1 via the lines 12, 13, 14, 15 and 16 without cleaning. As is apparent from Fig. 1, the nozzle 19 is mounted in the cooling air flow. A suitable design for their cross-section can achieve a significant driving force for the cooling air flow. This ejector effect alone or in combination with a fan can cause the gas circulation required to cool the drops and the powder.

Die Erfindung ermöglicht es, die Höhe der Granulieranlage zu reduzieren. Dies wird dadurch erreicht, daß der Gasstrom rinnenförmig gemacht wird, so daß man einen Gießstrahl direkt zu Tröpfchen zertrümmern kann, die ein Pulver von geeigneter Korngröße bilden, ohne daß der Tropfenstrahl von einem kreuzenden zweiten Gasstraht geschnitten wird. Bekannte effektive Granulieranlagen, bei denen Gas als Granuliermittel benutzt wird, erfordern Kühltürme, die mehr als sechs Meter hoch sind. Hierdurch sind teure hohe Gebäude erforderlich, und außerdem benötigt man teure Transportmittel zum vertikalen Transport von Rohmaterial für Schmelzenöfen oder für geschmolzenes Metall. Die Granulieranlage nach der Erfindung kann in Behältern untergebracht werden, die nur drei Meter hoch sind. Hierdurch kann man bei Neubauten große Ersparnisse erzielen. Vor allem kann die Anlage in bereits vorhandenen Eisenwerksgebäuden untergebracht werden, und man kann die in diesen vorhandenen Schmelzanlagen und Transport-Hilfsmittel verwenden. Das bedeutet, daß bei der Umstellung auf die Pulverherstellung nach der Erfindung relativ geringe Kosten entstehen.The invention makes it possible to reduce the height of the granulating plant. This is achieved by making the gas flow channel-shaped so that a pouring jet can be broken up directly into droplets which form a powder of a suitable grain size without the droplet jet from crossing second gas jet is cut. Known effective pelletizers using gas as the pelletizer require cooling towers that are more than six meters high. This requires expensive high-rise buildings and expensive transportation means for the vertical transportation of raw material for melting furnaces or for molten metal. The granulating plant according to the invention can be accommodated in containers that are only three meters high. As a result, you can achieve great savings in new buildings. Above all, the plant can be accommodated in existing ironworks buildings, and you can use the smelting plants and transport aids available in these. This means that the changeover to powder production according to the invention results in relatively low costs.

Claims (14)

1. A method for granulating a metallic melt by atomizing a vertical tap stream of the melt with the help of a jet of gas escaping under high pressure from a nozzle and hitting the tap stream at its side at high velocity, thereby atomizing the tap stream into droplets and throwing the droplets to the side on a substantially parabolic trajectory and cooling the droplets into powder the grains of which are preferably of sphericai shape, characterized in that the gas jet (22) is formed as a channel open at the top and with a preferably V-like cross-section intersecting the tap stream of melt (18) such that the center of the tap stream lies in or near the vertical symmetry plane of the gas jet (22), and that a second gas jet (26) is provided having, with regard to the tap stream (18), the same main direction as the channel-formed gas jet (22), but being directed obliquely downwards towards the bottom of the channel of the channel-formed gas jet (22).
2. Method according to claim 1, characterized in that the gas jet (22) is directed substantially horizontally.
3. Method according to claim 1, characterized in that the gas jet is directed such that the angle (x) between the gas jet and the tap stream is between 45° and 135°, preferably between 60° and 100°.
4. Method according to claim 3, characterized in that the second gas jet (26) is directed so that it hits the tap stream (18) within the channel-shaped gas jet (22).
5. Method according to claim 3, characterized in that the second gas jet (26) is directed substantially towards the point of intersection between the tap stream (18) and the bottom of the channel-shaped gas jet (22).
6. Method according to claim 3, characterized in that the channel-shaped gas jet (22) and the second gas jet (26) are supplied with gas of different pressure.
7. Method according to claim 6, characterized in that the shape of the parabolic trajectory on which the droplets and pulver particals follow under the effect of their sideways acceleration is influenced by controlling the pressure of the gas jet (22, 26).
8. Method according to any of the preceding claims, characterized in reutilizing the gas, whereby one portion of the gas is cooled, cleaned, compressed, and supplied to the nozzles (19, 20), while another portion is cooled and circulated in order to remove heat.
9. Apparatus for carrying out the method according to any of the preceding claims, characterized by a closed housing (1), by a casting box (5) with a tapping hole (17) opening into the granulating section (2) of the housing (1) and capable of forming a tap stream (18), by a nozzle (19) capable of forming a channel-shaped gas jet (22) directed to intersect the tap stream (1) by a cooling section (3), the shape of which is adapted to the shape of the parabolic trajectory for droplets and powder, by means for withdrawing the produced powder, by means for supplying gas to the apparatus, and by a second nozzle (20) shaped such as to create a gas jet (26) which is directed obliquely towards the bottom of the channel-shaped gas jet (22) and towards the tap stream of melt.
10. Apparatus according to claim 9, characterized in that a ladle (6) is included in the granulation section (2) of the housing (1) for collecting melt at the start of the tapping and in case of interruption of the gas supply to the jetforming gas nozzles (19,20).
11. Apparatus according to claim 9 or 10, characterized in that a return conduit (12, 13, 14, 15,16) is located between the cooling section (3) of the housing (1) and the granulating section (2).
12. Apparatus according to claim 11, characterized in that section (2) of the housing (1) is shaped such that the gas jet (22) brings about an ejector effect which causes circulation of gas.
13. Apparatus according to claim 11, characterized in that a cooler (11) is arranged to cool the gas circulating through the housing (1) and the conduit (12, 13, 14, 15, 16).
14. Apparatus according to any of claim 9 to 13, characterized in that the casting box (5) has two or more orifices and that the granulating section of the apparatus includes nozzles (19) which create a channel-formed gas jet (22) for each of the tap streams (18) from the casting box (5).
EP79102441A 1978-07-21 1979-07-16 Method and device for granulating a metal melt so as to produce powder Expired EP0007536B1 (en)

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SE7808028A SE412712B (en) 1978-07-21 1978-07-21 PROCEDURE AND PLANT FOR THE PREPARATION OF POWDER THROUGH MERGER GRANULATION
SE7808028 1978-07-21

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EP0007536A1 EP0007536A1 (en) 1980-02-06
EP0007536B1 true EP0007536B1 (en) 1982-05-12

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JP (1) JPS5518593A (en)
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SE412712B (en) 1980-03-17
JPS5518593A (en) 1980-02-08
BR7904670A (en) 1980-04-15
AU4895079A (en) 1980-01-24
SE7808028L (en) 1980-01-23
ES482659A1 (en) 1980-09-01
AU528552B2 (en) 1983-05-05
EP0007536A1 (en) 1980-02-06
DE2962800D1 (en) 1982-07-01
US4385878A (en) 1983-05-31
CA1125964A (en) 1982-06-22

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