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EP0149027B1 - Process and apparatus for manufacturing spheroidal metal particles - Google Patents

Process and apparatus for manufacturing spheroidal metal particles Download PDF

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Publication number
EP0149027B1
EP0149027B1 EP84112730A EP84112730A EP0149027B1 EP 0149027 B1 EP0149027 B1 EP 0149027B1 EP 84112730 A EP84112730 A EP 84112730A EP 84112730 A EP84112730 A EP 84112730A EP 0149027 B1 EP0149027 B1 EP 0149027B1
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Prior art keywords
gas
process according
hot gas
gas stream
particles
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German (de)
French (fr)
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EP0149027A3 (en
EP0149027A2 (en
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Wolfgang Seidler
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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
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/06—Metallic powder characterised by the shape of the particles
    • B22F1/065—Spherical particles
    • 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
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy

Definitions

  • the invention is directed to a method of the type specified in the preamble of claim 1 and a device as specified in the category in claim 15 for producing spherical particles.
  • US-A-2 334 578 discloses a process for the production of spherical glass particles using raw particles which are of the order of magnitude of the spherical particles to be produced. These raw particles are introduced from above into a high-energy stream of hot gas which is directed against gravity, the heating of the gas stream only causing the particle surface to melt, resulting in spherical particles.
  • the spherical particles that form are discharged from the gas stream when they enter the core area of the gas stream without being in a state of suspension beforehand, ie. H. the residence time in the hot zone of the gas stream is so short that only the desired melting of the particle surface can take place, there is no complete melting of the particle material.
  • Such a method is therefore not suitable for producing spherical particles from metal parts such as scrap or chips, since the related metal parts are significantly larger than the desired spherical metal particles to be produced.
  • the invention is therefore based on the object of specifying a method and a device for producing spherical metallic particles, in particular for use as abrasive, from substantially larger raw particles, which is uncomplicated and economical and which provides spherical, crack-free abrasive particles of high uniformity.
  • a device for this purpose should be able to be operated outside of a metal smelter or foundry without taking up much space, without any risks. Furthermore, it should be possible to create it with comparatively low investment costs and work economically in production, e.g. B., by extensive heat recovery.
  • a procedural solution to the task is achieved through the characterizing features of the new main claim. It is surprisingly simple and economical with the process to produce just enough molten material in each case that abrasive particles in status nascendi can be produced from it in a continuous process, the particle size of the raw material being irrelevant. Because of the suspended state of the introduced raw particles in the melt fluidized bed, a complete melting of the raw material is carried out, as a result of which small spherical droplets are atomized finely distributed by the gas stream, which are subsequently discharged by the gas stream and cooled.
  • the generation of a uniform fluidized bed is favored in that, according to a further proposal, the solid particles are given in the form of tablet-molded bodies which are molded from metal processing or fine shredder scrap and come out.
  • This is advantageously achieved by using shaped bodies of approximately the same dimensions and / or the same weight as the starting material. Under certain circumstances, it is provided that a shaped body approximately corresponds in shape and weight to a penny coin of German currency. Shaped bodies of this type are known with regard to their behavior in gas flows and can easily be produced on small presses.
  • An advantageous generation of the hot gas flow which can be achieved with simple means, can be achieved by using a burner charged with fuel gas and oxygen.
  • an expedient embodiment provides that a reducing gas atmosphere is set in the hot gas stream. This is advantageous in order to avoid decarburization of the generated particles.
  • This flow formation is favored by the fact that a flow channel designed as a Venturi nozzle is used to guide the hot gas flow.
  • a magnetic field is applied from the outside in the region or above the zone of the fluidized bed.
  • a ferromagnetic part arriving at falling speed is reliably braked by the magnetic field, so that it cannot fall down under any circumstances.
  • the possibility of using this magnetic field makes use of the knowledge that a particle loses its ferromagnetic property before it has reached the melting temperature, which is why the magnetic field has no retarding influence when the molten particles are discharged.
  • the hot gas stream is surrounded by a stream of jacket gas that cools the stream.
  • the kinetic energy of the jacket gas can at least correspond to that of the hot gas stream.
  • the jacket gas flow atomizes the Melt to droplets and discharge of the droplets, while the hot gas stream essentially provides the thermal energy for the melting process.
  • the method according to the invention is particularly economical.
  • the temperature of the jacket gas can be significantly lower than that of the hot gas stream.
  • the temperature of the hot gas stream is controlled in order to achieve a predetermined mean arithmetic particle size of the particles.
  • the temperature of the hot gas stream can be regulated according to the resulting mean arithmetic grain size with a constant feed quantity.
  • the method provides that the collected particles are subjected to a classification process, preferably by screening or sieving.
  • the dropping out of the finished product during the screening can be added to the starting material.
  • the proportion of dropouts is small, but adding them improves the pressing process.
  • the primary energy in the process is advantageously used economically in that waste heat from the hot gas stream is used to preheat the charged solid particles and / or jacket gas, or exhaust gas from the fluidized bed furnace can be collected and reused as jacket gas.
  • a device for producing spherical metallic particles, in particular for use as an abrasive, for carrying out the method according to claims 1-14 corresponds to the features of device claims 15-21.
  • the most important element of the device for carrying out the invention is a fluidized bed furnace 1 with a furnace wall 8.
  • This furnace wall 8 forms a flow guide body 9 with a flow channel 10 which widens continuously from bottom to top.
  • a device 2 for generating hot gas is arranged below the flow channel 10.
  • this is designed as a plasma torch 31 and has a feed 32 and a feed 33 for plasma gas.
  • a feed 34 for electrical energy, for example for generating an arc, is also provided.
  • the plasma torch has a nozzle mouthpiece 35 in the form of an acceleration nozzle.
  • a nozzle 36 with an annular outlet channel 37 is arranged around this nozzle mouthpiece 35.
  • the nozzle 36 serves to supply jacket gas 15 and is connected to the ring channel 14. This jacket gas is supplied through line 38 and an actuator 39.
  • the actuator 39 is set by a pressure sensor 40 depending on the pressure.
  • the plasma torch 31 supplies a hot gas stream 3 which flows through the flow channel 10 of the fluidized bed furnace 1 with relatively high kinetic and thermal energy.
  • the feed container 4 is arranged above the fluidized bed furnace 1. It has a metering discharge 5 with a discharge member 20 z. B. in the form shown, or in the form of a metering channel.
  • the feed container 4 is formed with a gas-permeable bottom 19 and closed at the top with an entry lock 21. On the pressure side, this is connected to a compressed gas line 24, which branches at points 41 into lines 18 and 38 for cooling gas and jacket gas.
  • a collecting container 25 which surrounds the fluidized bed furnace 1 in a ring shape, is arranged with a conically inclined bottom 26.
  • the furnace wall 8 is preferably made of porous, highly refractory sintered material. It is surrounded by a double wall 16 which, together with the furnace wall 8, encloses a coolant space 17 surrounding it.
  • a gaseous cooling medium is supplied to the coolant chamber 17 via the line 18.
  • a water injection 43 can be provided to condition the cooling medium.
  • the cooling medium can cool through the furnace wall 8 according to the arrows 44 through the furnace wall 8 and generate a further insulating coolant curtain between the hot gas stream 3 and the furnace wall 8.
  • a magnet system 12 is arranged on the outside 11 of the fluidized bed furnace 1 in the region or just above the fluidized bed 45. This is such that its magnetic field 13 (indicated by fine dashed lines) passes through the flow channel 10 in its almost narrowest area above the fluidized bed 45. This magnetic field 13 causes bodies 46 of the feed material falling from the feed container 4 to be braked and thus lose their falling energy before they enter the fluidized bed 45. With a lower arrangement of the magnet system 12, braking and holding the falling bodies 46 in the fluidized bed 45 is also possible, at the latest until they are liquid.
  • a radiation pyrometer 27 of measuring and control devices is arranged in the exemplary embodiment shown. This detects the temperature of the fluidized bed 45 and converts the determined value into an electrical signal. This signal is applied with the signal line 28 to the actuator 29 in the feed 32 for plasma gas and the actuator 30 in the feed 33 for plasma gas.
  • Another actuator 47 for electrical energy can also be controlled directly by the signal line 28 or via a converter (not shown) or controller.
  • the plasma torch 31 is ignited and thereby a hot gas stream 3 is generated which passes through the fluidized bed furnace 1 or its flow channel 10 with a gas jet 3. This is rich in kinetic and thermal energy.
  • the gas suction device 23 is put into operation. It sucks hot gas rising from the fluidized bed furnace 1 through the gas-permeable base 19 and presses it through the line 24 and the branch line 38 into the annular channel 14 of the nozzle 36. With a sufficiently high one generated by the gas suction device 23 Pressure emerges from the ring channel 14 through the outlet channel 37 of the nozzle 36 jacket gas 15 at a speed substantially above the speed of the hot gas.
  • the bodies 46 orient themselves towards the center of the stabilized fluidized bed 45. They are melted here by the plasma in a very short time and a fluidized bed melt forms in the region of the fluidized bed 45. This consists of individual droplets 49. These individual droplets 49 are discharged from the fluidized bed furnace 1 by absorbing kinetic energy after reaching sufficient smallness in a throwing parabola 42 and solidify at the zenith of the throwing parah 42 in the state without acceleration. This gives bodies of an ideal spherical shape. These are collected in the collecting device 6 as finished goods 7 and deducted from them in accordance with the arrows 48.
  • an adjustable pressure of the jacket gas 15 in front of the nozzle opening 37 is kept constant with the help of a pressure sensor 40 and the actuator 39 influenced by this.
  • a radiation pyrometer 27 which continuously determines the temperature, converts it into electrical control signals and, via the signal line 28 or a (not shown) controller of a conventional type, the control elements 47 for the supply of electrical energy and 29 and 30 for the supply of gases.
  • Cooling the furnace wall 8 also ensures its resistance in the high temperature area.
  • the invention results in an unprecedentedly favorable production of spherical metallic particles using state-of-the-art technical means, which leads to low energy consumption in the production of a product of unprecedented quality.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Nanotechnology (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)
  • Furnace Details (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)

Abstract

A process is disclosed for producing spherical metallic particles which are especially suited for use as an abrasive wherein a particulate metal starting material is liquified by counter-current flow with a hot gas stream which places the solid and liquid particles in a fluidized state and the liquified particles are droplets upon reaching a sufficiently small size are carried upwardly out of the fluidized zone and then cooled to form the spherical particles. An apparatus for carrying out the process is also disclosed.

Description

Die Erfindung richtet sich auf ein Verfahren der im Oberbegriff des Anspruches 1 angegebenen Gattung und eine Vorrichtung, wie sie gattungsgemäß im Anspruch 15 angegeben ist zum Herstellen von kugelförmigen Partikeln.The invention is directed to a method of the type specified in the preamble of claim 1 and a device as specified in the category in claim 15 for producing spherical particles.

In der US-A-2 334 578 ist ein Verfahren zur Herstellung von kugelförmigen Glaspartikeln angegeben, bei dem Rohteilchen verwendet werden, die in der Größenordnung der herzustellenden kugelförmigen Partikel liegen. Diese Rohteilchen werden von oben in einen der Schwerkraft entgegengerichteten, energiereichen Strom von hei-βem Gas aufgegeben, wobei durch die Erhitzung im Gasstrom lediglich ein Anschmelzen der Teilchenoberfläche stattfindet, wodurch sich kugelförmige Partikel ergeben. Dabei werden die sich bildenden kugelförmigen Partikel beim Eindringen in den Kembereich des Gasstromes vom Gasstrom ausgetragen, ohne daß sie sich vorher in einem Schwebezustand befinden, d. h. die Aufenthaltszeit in der heißen Zone des Gasstromes ist so kurz, daß nur die gewünschte Aufschmelzung der Teilchenoberfläche ablaufen kann, ein völliges Aufschmelzen des Teilchenmateriales findet nicht statt.US-A-2 334 578 discloses a process for the production of spherical glass particles using raw particles which are of the order of magnitude of the spherical particles to be produced. These raw particles are introduced from above into a high-energy stream of hot gas which is directed against gravity, the heating of the gas stream only causing the particle surface to melt, resulting in spherical particles. The spherical particles that form are discharged from the gas stream when they enter the core area of the gas stream without being in a state of suspension beforehand, ie. H. the residence time in the hot zone of the gas stream is so short that only the desired melting of the particle surface can take place, there is no complete melting of the particle material.

Ein solches Verfahren ist deshalb nicht zur Herstellung kugelförmiger Partikel aus Metallteilen wie Schrott oder Späne geeignet, da die verwandten Metallteile wesentlich größer als die gewünschten, zu erzeugenden kugelförmigen Metallpartikel sind.Such a method is therefore not suitable for producing spherical particles from metal parts such as scrap or chips, since the related metal parts are significantly larger than the desired spherical metal particles to be produced.

Der Erfindung liegt deshalb die Aufgabe zugrunde, ein Verfahren und ein Vorrichtung zur Herstellung von kugelförmigen metallischen Partikeln, insbesondere zur Verwendung als Strahlmittel, aus wesentlich größeren Rohteilchen anzugeben, das unkompliziert und wirtschaftlich ist und kugelförmige, rißfreie Strahlmittelpartikel von hoher Gleichmäßigkeit liefert. Eine Vorrichtung hierfür soll außerhalb einer Metallhütte oder Gießerei bei geringem Raumbedarf ohne Risiken betrieben werden können, soll darüber hinaus mit vergleichsweise niedrigen Investitionskosten erstellbar sein und in der Produktion wirtschaftlich arbeiten, z. B., durch weitgehenden Wärmerückgewinn.The invention is therefore based on the object of specifying a method and a device for producing spherical metallic particles, in particular for use as abrasive, from substantially larger raw particles, which is uncomplicated and economical and which provides spherical, crack-free abrasive particles of high uniformity. A device for this purpose should be able to be operated outside of a metal smelter or foundry without taking up much space, without any risks. Furthermore, it should be possible to create it with comparatively low investment costs and work economically in production, e.g. B., by extensive heat recovery.

Eine Lösung der gestellten Aufgabe gelingt verfahrensmäßig durch die kennzeichnenden Merkmale des neuen Hauptanspruches. Dabei gelingt es mit dem Verfahren überraschend einfach und wirtschaftlich, jeweils gerade soviel geschmolzenes Material herzustellen, daß aus diesem in einem kontinuierlichen Verfahren Strahlmittelpartikel im status nascendi hergestellt werden können, wobei die Teilchengröße des Rohmateriales keine Rolle spielt. Durch den Schwebezustand der eingeleiteten Rohteilchen in der Schmelzwirbelschicht wird nämlich eine vollständige Aufschmelzung des Rohmateriales durchgeführt, wodurch dann durch den Gasstrom fein verteilt kleine kugelförmige Tröpfchen zerstäubt werden, welche anschließend durch den Gasstrom ausgetragen und abgekühlt werden.A procedural solution to the task is achieved through the characterizing features of the new main claim. It is surprisingly simple and economical with the process to produce just enough molten material in each case that abrasive particles in status nascendi can be produced from it in a continuous process, the particle size of the raw material being irrelevant. Because of the suspended state of the introduced raw particles in the melt fluidized bed, a complete melting of the raw material is carried out, as a result of which small spherical droplets are atomized finely distributed by the gas stream, which are subsequently discharged by the gas stream and cooled.

Weitere Vorteile der Erfindung ergeben sich aus den Unteransprüchen.Further advantages of the invention emerge from the subclaims.

Die Erzeugung einer gleichmäßigen Wirbelschicht wird dadurch begünstigt, daß nach einem weiteren Vorschlag die Feststoffteilchen in Form von aus Metallbearbeitung oder feinem Shredderschrott und Ausfallkömung formgepreßter tablettierter Körper aufgegeben werden. Mit Vorteil wird dies dadurch erreicht, daß Formkörper von annähernd gleichen Abmessungen und/oder gleichem Gewicht als Ausgangsmaterial verwendet werden. Unter Umständen ist dabei vorgesehen, daß ein Formkörper in Form und Gewicht annähernd einer Pfennigmünze Deutscher Währung entspricht. Derartige Formkörper sind bezüglich ihres Verhaltens in Gasströmungen bekannt und können einfach auf kleinen Pressen hergestellt werden.The generation of a uniform fluidized bed is favored in that, according to a further proposal, the solid particles are given in the form of tablet-molded bodies which are molded from metal processing or fine shredder scrap and come out. This is advantageously achieved by using shaped bodies of approximately the same dimensions and / or the same weight as the starting material. Under certain circumstances, it is provided that a shaped body approximately corresponds in shape and weight to a penny coin of German currency. Shaped bodies of this type are known with regard to their behavior in gas flows and can easily be produced on small presses.

Eine vorteilhafte und mit einfachen Mitteln erzielbare Erzeugung des Heißgasstroms kann and durch Verwendung eines mit Brenngas und Sauerstoff beschickten Brenners erreicht werden.An advantageous generation of the hot gas flow, which can be achieved with simple means, can be achieved by using a burner charged with fuel gas and oxygen.

Auch kann mit Vorteil zur Erzeugung des Heißgasstroms ein Plasmabrenner verwendet werden, dessen Flamme besonders heiß und dessen Gasstrom besonders schnell ist.It is also advantageous to use a plasma torch to generate the hot gas flow, the flame of which is particularly hot and the gas flow of which is particularly fast.

Weiter sieht eine zweckmäßige Ausgestaltung vor, daß im Heißgasstrom eine reduzierende Gasatmosphäre eingestellt wird. Dies ist vorteilhaft, um eine Randentkohlung der erzeugten Partikel zu vermeiden.Furthermore, an expedient embodiment provides that a reducing gas atmosphere is set in the hot gas stream. This is advantageous in order to avoid decarburization of the generated particles.

Begünstigt wird diese Strömungsausbildung dadurch, daß zur Führung des Heißgasstroms ein als Venturidüse ausgebildeter Strömungskanal verwendet wird.This flow formation is favored by the fact that a flow channel designed as a Venturi nozzle is used to guide the hot gas flow.

Beim Aufgeben der Metallteile des Ausgangsmaterials muß die diesen Teilchen durch den Fall innewohnende kinetischen Energie ausgeglichen werden. Mit Vorteil ist daher vorgesehen, daß im Bereich bzw. oberhalb der Zone der Wirbelschicht von außen her ein Magnetfeld angelegt ist. Dadurch wird ein mit Fallgeschwindigkeit ankommendes ferromagnetisches Teil vom Magnetfeld zuverlässig gebremst, so daß es keinesfalls nach unten durchfallen kann. Die Möglichkeit der Verwendung dieses Magnetfeldes macht dabei von der Erkenntnis Gebrauch, daß ein Partikel bevor es Schmelztemperatur erreicht hat, seine ferromagnetische Eigenschaft verliert, weshalb das Magnetfeld bei der Austragung der geschmolzenen Partikel keinen verzögernden Einfluß ausübt.When the metal parts of the starting material are given up, the kinetic energy inherent in these particles must be compensated for by the fall. It is therefore advantageously provided that a magnetic field is applied from the outside in the region or above the zone of the fluidized bed. As a result, a ferromagnetic part arriving at falling speed is reliably braked by the magnetic field, so that it cannot fall down under any circumstances. The possibility of using this magnetic field makes use of the knowledge that a particle loses its ferromagnetic property before it has reached the melting temperature, which is why the magnetic field has no retarding influence when the molten particles are discharged.

Eine weitere wesentliche Ausgestaltung des Verfahrens sieht vor, daß der Heißgasstrom von einem Strom kühlenden Mantelgasstrom umgeben ist. Dabei kann die kinetische Energie des Mantelgases mindestens derjenigen des Heißgasstroms entsprechen. Andererseits kann es von Vorteil sein, wenn die kinetische Energie des Mantelgases wesentlich größer ist als diejenige des Heißgasstroms. In diesem Falle übernimmt die Mantelgasströmung die Zerstäubung der Schmelze zu Tröpfchen und das Austragen der Tröpfchen, während der Heißgasstrom im wesentlichen die thermische Energie für den Schmelzprozeß liefert. Auf diese Weise gestaltet sich das Verfahren nach der Erfindung besonders wirtschaftlich. Dabei kann die Temperatur des Mantelgases wesentlich niedriger sein als die des Heißgasstroms.Another essential embodiment of the method provides that the hot gas stream is surrounded by a stream of jacket gas that cools the stream. The kinetic energy of the jacket gas can at least correspond to that of the hot gas stream. On the other hand, it can be advantageous if the kinetic energy of the jacket gas is significantly greater than that of the hot gas flow. In this case, the jacket gas flow atomizes the Melt to droplets and discharge of the droplets, while the hot gas stream essentially provides the thermal energy for the melting process. In this way, the method according to the invention is particularly economical. The temperature of the jacket gas can be significantly lower than that of the hot gas stream.

In weiterer Ausgestaltung ist mit Vorteil vorgesehen, daß zur Erzielung einer vorbestimmten mittleren arithmetischen Korngröße der Partikel die Temperatur des Heißgasstromes gesteuert wird. Dabei kann bei konstanter Aufgabemenge die Temperatur des Heißgasstromes nach der sich ergebenden mittleren arithmetischen Korngröße geregelt werden.In a further embodiment, it is advantageously provided that the temperature of the hot gas stream is controlled in order to achieve a predetermined mean arithmetic particle size of the particles. The temperature of the hot gas stream can be regulated according to the resulting mean arithmetic grain size with a constant feed quantity.

Weiter können zur Beeinflussung der Kugelform der Partikel zusätzlich eine oder mehrere der folgenden Parameter eingestellt werden :

  • - Menge des zugeführten Mantelgases,
  • - Temperatur des Mantelgases,
  • - Energiegehalt des Mantelgases,
  • - Energie des Magnetfeldes.
One or more of the following parameters can also be set to influence the spherical shape of the particles:
  • - amount of jacket gas supplied,
  • - temperature of the jacket gas,
  • - energy content of the jacket gas,
  • - energy of the magnetic field.

In weiterer vorteilhafter Ausgestaltung sieht das Verfahren vor, daß die aufgefangenen Partikel einem Klassifiziervorgang, vorzugsweise durch Sichtung oder Siebung, unterzogen werden. Dabei können die bei der Sichtung aus dem Fertiggut ausgeschiedenen Ausfallkömungen dem Ausgangsmaterial zugeschlagen werden. Der Anteil der Ausfallkömungen ist zwar gering, ihre Zumischung verbessert aber den Pressvorgang.In a further advantageous embodiment, the method provides that the collected particles are subjected to a classification process, preferably by screening or sieving. In this case, the dropping out of the finished product during the screening can be added to the starting material. The proportion of dropouts is small, but adding them improves the pressing process.

Mit Vorteil ergibt sich eine ökonomische Nutzung der Primärenergie beim Verfahren dadurch, daß Abwärme des Heißgasstroms zur Vorwärmung der aufgegebenen Feststoffteilchen und/oder von Mantelgas verwendet wird, bzw. es kann Abgas des Wirbelschichtofens aufgefangen und als Mantelgas wiederverwendet werden.The primary energy in the process is advantageously used economically in that waste heat from the hot gas stream is used to preheat the charged solid particles and / or jacket gas, or exhaust gas from the fluidized bed furnace can be collected and reused as jacket gas.

Eine Vorrichtung zur Herstellung von kugelförmigen metallischen Partikeln, insbesondere zur Verwendung als Strahlmittel, zur Durchführung des Verfahrens nach den Ansprüchen 1-14 entspricht den Merkmalen der Vorrichtungsansprüche 15-21.A device for producing spherical metallic particles, in particular for use as an abrasive, for carrying out the method according to claims 1-14 corresponds to the features of device claims 15-21.

Die Erfindung wird in der Zeichnung in einer bevorzugten Vorrichtungs-Ausführungsform gezeigt, wobei aus der Zeichnung weitere Einzelheiten der Erfindung entnehmbar sind.The invention is shown in the drawing in a preferred embodiment of the device, further details of the invention being apparent from the drawing.

Die Vorrichtung zur Durchführung der Erfindung weist als wesentlichstes Element einen Wirbelschichtofen 1 mit einer Ofenwand 8 auf. Diese Ofenwand 8 bildet einen Strömungsleitkörper 9 mit sich stetig von unten nach oben erweiternden Strömungskanal 10. Unterhalb des Strömungskanals 10 ist eine Einrichtung 2 zur Erzeugung von Heißgas angeordnet. Diese ist im gezeigten Ausführungsbeispiel als Plasmabrenner 31 ausgebildet und weist eine Zuführung 32 und eine Zuführung 33 für Plasmagas auf.The most important element of the device for carrying out the invention is a fluidized bed furnace 1 with a furnace wall 8. This furnace wall 8 forms a flow guide body 9 with a flow channel 10 which widens continuously from bottom to top. A device 2 for generating hot gas is arranged below the flow channel 10. In the exemplary embodiment shown, this is designed as a plasma torch 31 and has a feed 32 and a feed 33 for plasma gas.

Weiterhin ist eine Zuführung 34 für elektrische Energie, beispielsweise zur Erzeugung eines Lichtbogens, vorgesehen. Der Plasmabrenner besitzt ein Düsenmundstück 35 in Form einer Beschleunigungsdüse. Um dieses Düsenmundstück 35 ist eine Düse 36 mit ringförmigem Austrittskanal 37 angeordnet. Die Düse 36 dient zur Zuführung von Mantelgas 15 und ist an den Ringkanal 14 angeschlossen. Diesem wird Mantelgas durch die Leitung 38 und ein Stellorgan 39 zugeführt. Das Stellorgan 39 wird von einem Drucksensor 40 druckabhängig eingestellt.A feed 34 for electrical energy, for example for generating an arc, is also provided. The plasma torch has a nozzle mouthpiece 35 in the form of an acceleration nozzle. A nozzle 36 with an annular outlet channel 37 is arranged around this nozzle mouthpiece 35. The nozzle 36 serves to supply jacket gas 15 and is connected to the ring channel 14. This jacket gas is supplied through line 38 and an actuator 39. The actuator 39 is set by a pressure sensor 40 depending on the pressure.

Der Plasmabrenner 31 liefert einen Heißgasstrom 3, der den Strömungskanal 10 des Wirbelschichtofens 1 mit relativ hoher kinetischer und thermischer Energie durchströmt.The plasma torch 31 supplies a hot gas stream 3 which flows through the flow channel 10 of the fluidized bed furnace 1 with relatively high kinetic and thermal energy.

Oberhalb des Wirbelschichtofens 1 ist der Aufgabebehälter 4 angeordnet. Er weist einen dosierenden Austrag 5 mit einem Austragsorgan 20 z. B. in der gezeigten Form, oder aber in Form einer Dosierrinne auf. Der Aufgabebehälter 4 ist mit einem gasdurchlässigem Boden 19 ausgebildet und nach oben hin mit einer Einträgsschleuse 21 verschlossen. Diese steht druckseitig mit einer Druckgasleitung 24 in Verbindung, die sich an der Stelle 41 in die Leitungen 18 und 38 für Kühlgas und Mantelgas verzweigt.The feed container 4 is arranged above the fluidized bed furnace 1. It has a metering discharge 5 with a discharge member 20 z. B. in the form shown, or in the form of a metering channel. The feed container 4 is formed with a gas-permeable bottom 19 and closed at the top with an entry lock 21. On the pressure side, this is connected to a compressed gas line 24, which branches at points 41 into lines 18 and 38 for cooling gas and jacket gas.

. Zum Auffangen der aus dem Wirbelschichtofen 1 in einer Wurfparabel 42 ausgetragenen Fertiggutteilchen 7 ist ein den Wirbelschichtofen 1 ringförmig umgebender Auffangbehälter 25 mit konisch nach außen geneigtem Boden 26 angeordnet.. To collect the finished product particles 7 discharged from the fluidized bed furnace 1 in a throwing parabola 42, a collecting container 25, which surrounds the fluidized bed furnace 1 in a ring shape, is arranged with a conically inclined bottom 26.

Die Ofenwand 8 besteht vorzugsweise aus porösem, hochfeuerfestem Sintermaterial. Sie ist von einer Doppelwand 16 umgeben, die zusammen mit der Ofenwand 8 einen diese umgebenden Kühlmittelraum 17 einschließt. Mit der Leitung 18 wird dem Kühlmittelraum 17 ein gasförmiges Kühlmedium zugeführt. Dabei kann zur Konditionierung des Kühlmediums eine Wassereindüsung 43 vorgesehen sein.The furnace wall 8 is preferably made of porous, highly refractory sintered material. It is surrounded by a double wall 16 which, together with the furnace wall 8, encloses a coolant space 17 surrounding it. A gaseous cooling medium is supplied to the coolant chamber 17 via the line 18. A water injection 43 can be provided to condition the cooling medium.

Im Zusammenwirken mit der porösen Ofenwand 8 wird erreicht, daß das Kühlmedium unter Kühlung der Ofenwand 8 entsprechend den Pfeilen 44 durch die Ofenwand 8 hindurch treten kann und einen weiteren isolierenden Kühlmittelschleier zwischen dem Heißgasstrom 3 und der Ofenwand 8 erzeugt.In cooperation with the porous furnace wall 8 it is achieved that the cooling medium can cool through the furnace wall 8 according to the arrows 44 through the furnace wall 8 and generate a further insulating coolant curtain between the hot gas stream 3 and the furnace wall 8.

Im Bereich, bzw. dicht oberhalb der Wirbelschicht 45 ist an der Außenseite 11 des Wirbelschichtofens 1 ein Magnetsystem 12 angeordnet. Dieses ist so beschaffen, daß sein Magnetfeld 13 (angedeutet durch feingestrichelte Linien) den Strömungskanal 10 in seinem annähernd engstem Bereich oberhalb der Wirbelschicht 45 durchsetzt. Dieses Magnetfeld 13 bewirkt, daß aus dem Aufgabebehälter 4 herabfallende Körper 46 des Aufgabegutes abgebremst werden und damit ihre Fallenergie verlieren, bevor sie in die Wirbelschicht 45 eintreten. Bei tieferer Anordnung des Magnetsystems 12 ist auch ein Abbremsen und Halten der herabfallenden Körper 46 in der Wirbelschicht 45 möglich, spätestens bis diese flüssig sind.A magnet system 12 is arranged on the outside 11 of the fluidized bed furnace 1 in the region or just above the fluidized bed 45. This is such that its magnetic field 13 (indicated by fine dashed lines) passes through the flow channel 10 in its almost narrowest area above the fluidized bed 45. This magnetic field 13 causes bodies 46 of the feed material falling from the feed container 4 to be braked and thus lose their falling energy before they enter the fluidized bed 45. With a lower arrangement of the magnet system 12, braking and holding the falling bodies 46 in the fluidized bed 45 is also possible, at the latest until they are liquid.

Zur Einstellung einer mittleren arithmetischen Korngröße des Fertiggutes 7 ist es erforderlich, die Temperatur der Wirbelschicht 45 einzustellen. Als Beispiel für eine hierfür mögliche Anordnung von Meß- und Regeleinrichtungen ist im gezeigten Ausführungsbeispiel ein Strahlungspyrometer 27 angeordnet. Dieses erfaßt die Temperatur der Wirbelschicht 45 und wandelt den ermittelten Wert in ein elektrisches Signal um. Dieses Signal wird mit der Signalleitung 28 dem Stellorgan 29 in der Zuführung 32 für Plasmagas und dem Stellorgan 30 in der Zuführung 33 für Plasmagas aufgeschaltet.To set an average arithmetic grain size of the finished product 7, it is necessary to set the temperature of the fluidized bed 45. As an example of a possible arrangement for this A radiation pyrometer 27 of measuring and control devices is arranged in the exemplary embodiment shown. This detects the temperature of the fluidized bed 45 and converts the determined value into an electrical signal. This signal is applied with the signal line 28 to the actuator 29 in the feed 32 for plasma gas and the actuator 30 in the feed 33 for plasma gas.

Ein weiteres Stellorgan 47 für elektrische Energie kann ebenfalls direkt oder über einen (nicht gezeigten) Wandler bzw. Regler von der Signalleitung 28 angesteuert sein.Another actuator 47 for electrical energy can also be controlled directly by the signal line 28 or via a converter (not shown) or controller.

Der Betrieb der gezeigten Vorrichtung, soweit er nicht bereits erwähnt wurde, läuft wie folgt ab : Zur Ingangsetzung der Vorrichtung wird der Plasmabrenner 31 gezündet und dadurch ein Heißgasstrom 3 erzeugt, der den Wirbelschichtofen 1 bzw. dessen Strömungskanal 10 mit einem Gasstrahl 3 durchsetzt. Dieser ist reich an kinetischer und thermischer Energie.The operation of the device shown, insofar as it has not already been mentioned, proceeds as follows: To start the device, the plasma torch 31 is ignited and thereby a hot gas stream 3 is generated which passes through the fluidized bed furnace 1 or its flow channel 10 with a gas jet 3. This is rich in kinetic and thermal energy.

Nunmehr wird die Gasabsaugeinrichtung 23 in Betrieb gesetzt Diese saugt aus dem Wirbelschichtofen 1 aufsteigendes heißes Gas durch den gasdurchlässigen Boden 19 und drückt dieses durch die Leitung 24 sowie die Zweigleitung 38 in den Ringkanal 14 der Düse 36. Bei einem von der Gasabsaugeinrichtung 23 erzeugten genügend hohen Druck tritt aus dem Ringkanal 14 durch den Austrittskanal 37 der Düse 36 Mantelgas 15 mit einer wesentlich über der Geschwindigkeit des Heißgases liegenden Geschwindigkeit aus.Now the gas suction device 23 is put into operation. It sucks hot gas rising from the fluidized bed furnace 1 through the gas-permeable base 19 and presses it through the line 24 and the branch line 38 into the annular channel 14 of the nozzle 36. With a sufficiently high one generated by the gas suction device 23 Pressure emerges from the ring channel 14 through the outlet channel 37 of the nozzle 36 jacket gas 15 at a speed substantially above the speed of the hot gas.

Durch dosierenden Austrag 5 über das Austragsorgan 20 werden nunmehr Körper 46 des im Aufgabebehälter vorrätig gehaltenen Aufgabegutes ausgetragen und gelangen entsprechend dem Pfeil 47 durch den Heißgasstrom 3 hindurchfallend zunächst in den Bereich des Magnetfeldes 13, in dem ihre Fallgeschwindigkeit abgebremst wird. Beim weiteren Niedersinken in die Wirbelschicht 45 werden die Körper 46 von der Wirbelschicht 45 aufgefangen. In dieser herrscht ein stabiles Gleichgewicht zwischen der Schwerkraft der eingetragenen Körper 46 und dem Impuls von Heißgasstrom 3 und Mantelgas 15.By means of metering discharge 5 via discharge element 20, bodies 46 of the feed material held in the feed container are now discharged and, according to arrow 47, first pass through hot gas flow 3 and into the area of magnetic field 13, in which their falling speed is slowed down. When sinking further down into the fluidized bed 45, the bodies 46 are caught by the fluidized bed 45. In this there is a stable equilibrium between the gravity of the entered bodies 46 and the momentum of hot gas flow 3 and jacket gas 15.

Weil das Mantelgas 15 eine wesentlich höhere Geschwindigkeit besitzt als das Plasmagas, orientieren sich die Körper 46 nach der Mitte der stabilisierten Wirbelschicht 45. Sie werden hier in kürzester Zeit durch das Plasma geschmolzen und es bildet sich im Bereich der Wirbelschicht 45 eine Wirbelschichtschmelze. Diese besteht aus Einzeltröpfchen 49. Diese Einzeltröpfchen 49 werden durch Aufnahme von kinetischer Energie nach Erreichen genügender Kleinheit in einer Wurfparabel 42 aus dem Wirbelschichtofen 1 ausgetragen und erstarren im Zenit der Wurfparabei 42 im beschleunigungslosen Zustand. So ergeben sich Körper von einer idealen Kugelform. Diese werden in der Auffangvorrichtung 6 als Fertiggut 7 aufgefangen und entsprechend den Pfeilen 48 daraus abgezogen.Because the jacket gas 15 has a significantly higher speed than the plasma gas, the bodies 46 orient themselves towards the center of the stabilized fluidized bed 45. They are melted here by the plasma in a very short time and a fluidized bed melt forms in the region of the fluidized bed 45. This consists of individual droplets 49. These individual droplets 49 are discharged from the fluidized bed furnace 1 by absorbing kinetic energy after reaching sufficient smallness in a throwing parabola 42 and solidify at the zenith of the throwing parah 42 in the state without acceleration. This gives bodies of an ideal spherical shape. These are collected in the collecting device 6 as finished goods 7 and deducted from them in accordance with the arrows 48.

Durch die Ausbildung des Aufgabebehälters 4 mit einem gasdurchlässigen Boden 19 und Anschluß an die Gasabzugseinrichtung 23 wird hei-βes Abgas aus dem Wirbelschichtofen in den Aufgabebehälter 4 eingesaugt. Dabei werden die darin eingelagerten Körper 46 des Aufgabegutes vorgewärmt. Hierdurch wird die Energiebilanz des Verfahrens sehr positiv beeinflußt. Eine gleiche positive Wirkung ergibt sich dadurch, daß das aus dem Aufgabebehälter 4 abgesaugte noch warme Abgas durch die Leitung 24 und die Zweigleitung 38 als Mantelgas 15 wieder in den Kreislauf zurückgeführt wird.By forming the feed container 4 with a gas-permeable bottom 19 and connecting it to the gas extraction device 23, hot exhaust gas is sucked out of the fluidized bed furnace into the feed container 4. The bodies 46 of the feed material stored therein are preheated. This has a very positive influence on the energy balance of the process. The same positive effect results from the fact that the warm exhaust gas extracted from the feed container 4 is returned to the circuit as line gas 15 through line 24 and branch line 38.

Weil die kinetische Energie des Mantelgases 15 für die gleichmäßige mittlere arithmetische Korngröße der Partikel 49 von Einfluß ist, wird mit Hilfe eines Drucksensors 40 und das von diesem beeinflußte Stellorgan 39 ein einstellbarer Druck des Mantelgases 15 vor der Düsenöffnung 37 konstant gehalten.Because the kinetic energy of the jacket gas 15 has an influence on the uniform mean arithmetic grain size of the particles 49, an adjustable pressure of the jacket gas 15 in front of the nozzle opening 37 is kept constant with the help of a pressure sensor 40 and the actuator 39 influenced by this.

Um die Schmelztemperatur der Schmelze im Bereich der Wirbelschicht 45 auf konstantem Temperatumiveau halten zu können, ist ein Strahlungspyrometer 27 vorgesehen, das die Temperatur laufend ermittelt, in elektrische Stellsignale umwandelt und über die Signalleitung 28 bzw. einen (nicht gezeigten) Regler üblicher Bauart die Stellorgane 47 für die Einspeisung der elektrischen Energie und 29 bzw. 30 für die Zufuhr der Gase beeinflußt.In order to be able to keep the melting temperature of the melt in the region of the fluidized bed 45 at a constant temperature level, a radiation pyrometer 27 is provided, which continuously determines the temperature, converts it into electrical control signals and, via the signal line 28 or a (not shown) controller of a conventional type, the control elements 47 for the supply of electrical energy and 29 and 30 for the supply of gases.

Eine Kühlung der Ofenwand 8 sorgt im übrigen für deren Widerstandsfähigkeit im Hochtemperaturgebiet.Cooling the furnace wall 8 also ensures its resistance in the high temperature area.

Insgesamt ergibt sich durch die Erfindung eine bisher unerreicht günstige Herstellung von kugelförmigen metallischen Partikeln unter Einsatz modemster technischer Mittel, der zu geringem Energieverbrauch bei der Herstellung eines Produktes bisher unerreichter Qualität führt.Overall, the invention results in an unprecedentedly favorable production of spherical metallic particles using state-of-the-art technical means, which leads to low energy consumption in the production of a product of unprecedented quality.

Claims (21)

1. A process for manufacturing spherical particles, wherein solid particles are loaded in a metered quantity into an energy-rich stream (3) of hot gas directed against the force of gravity, and are held thereby temporarily in suspension, are melted and made into a spherical shape, are then removed from the gas stream and then cooled and collected in the solid state, characterised in that the solid particles made of metal are completely melted in a melting fluidised bed (45) and atomised in the gas stream (3).
2. A process according to claim 1, characterised in that the solid particles are loaded in the form of compression moulded pre-formed bodies composed of swarf or fine shredder scrap and defective granules.
3. A process according to Claim 1 or 2, characterised in that for generating the hot gas stream, a burner supplied with fuel gas and oxygen or plasma torch (31) is used.
4. A process according to one of claims 1 to 3, characterised in that a reduced gas atmosphere is set in the hot gas stream (3).
5. A process according to one of claims 1 to 4, characterised in that the hot gas stream (3) is guided from the bottom upwards through a flow channel, which is partly formed as a fluidised bed furnace (1).
6. A process according to one of claims 1 to 5, characterised in that a flow channel formed as a Venturi tube is used for guiding the hot gas stream (3).
7. A process according to one of claims 1 to 6, characterised in that a magnetic field (13) is applied from outside in the region of the zones of the fluidised bed (45) or thereabove.
8. A process according to one of claims 1 to 7, characterised in that the hot gas stream (3) is surrounded by a stream of a cooler gas envelope (15).
9. A process according to one of claims 1 to 8, characterised in that the kinetic energy of the gas envelope (15) is at least the same as that of the hot gas stream (3) and in that its temperature is substantially lower than that of the hot gas stream (3).
10. A process according to one of claims 1 to 9, characterised in that, in order to achieve a predetermined arithmetic grain size of the particles, the temperature of the hot gas stream (3) is controlled.
11. A process according to one of claims 1 to 10, characterised in that, in order to control the spherical shape of the particles, additionally one or more of the following parameters are controlled :
- the quantity of gas supplied to the gas envelope (15),
- the temperature of the gas envelope (15),
- the energy content of the gas envelope (15),
- the energy of the magnetic field (13).
12. A process according to one of claims 1 to 11, characterised in that the collected particles are subjected to a classifying process, wherein the defective granules separated from the finished product during the classifying process are added to the starting material.
13. A process according to one of claims 1 to 12, characterised in that the heat given off by the hot gas stream (3) is used for pre-heating the solid particles (46) of the charge and/or for heating the gas envelope (15).
14. A process according to one of claims 1 to 13, characterised in that exhaust gas from the fluidised bed furnace (1) is collected and directly re-used for the gas envelope (15).
15. Apparatus for manufacturing spherical par- tides for carrying out the process according to one or more of claims 1 to 14, with a hot gas furnace comprising a device (2) for generating a hot gas stream (3), a furnace wall (8) formed as a flow-guiding body (9) with a flow channel (10) widening from the bottom upwards, a supply and/or charge container (4) with a metering extractor device (5), and a collecting_ device (6) for the finished product, characterised in that the hot gas furnace is formed as a fluidised bed furnace (1) heated from below and is equipped with a plasma torch (31) for completely melting and atomising the metal solid particles of the charge in the hot gas stream (3) of the plasma torch (31).
16. Apparatus according to claim 15, characterised in that a magnet system (12) with a magnetic field penetrating the fluidised bed is arranged on the outside (11) of the furnace wall (8).
17. Apparatus according to claim 15 or 16, characterised in that the plasma torch (2) has an annular channel (14) surrounding it on the outside for a gas envelope (15).
18. Apparatus according to one of claims 15 to 17, characterised in that the furnace wall (8) consists of a diamagnetic, temperature-resistant porous ceramics material and is surrounded by a double wall (16), which includes with the furnace wall (8) a cooling medium chamber (17) surrounding the said furnace wall, and in that the cooling medium chamber is connected to a duct (18) for carrying a preferably gaseous cooling medium.
19. Apparatus according to one of claims 15 to 18, characterised in that the charge container (4) has a gas-permeable base (19) or other gas inlet.
20. Apparatus according to one of claims 16 to 19, characterised in that the charge container (4) is closed at the top with an charging sluice (21) and is connected to a gas extraction device (23) by an extraction nozzle, the gas extraction device (23) being connected via a pipe (24) to the annular channel (14) for the gas envelope (15).
21. Apparatus according to one of claims 16 to 20, characterised in that the collecting device (6) has a container (25) with a conically outwardly inclined base (26), which container surrounds the fluidised bed furnace (1) in an annular manner.
EP84112730A 1983-12-20 1984-10-23 Process and apparatus for manufacturing spheroidal metal particles Expired - Lifetime EP0149027B1 (en)

Priority Applications (1)

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AT84112730T ATE49146T1 (en) 1983-12-20 1984-10-23 METHOD AND DEVICE FOR THE PRODUCTION OF SPHERE-SHAPED METALLIC PARTICLES.

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DE3345983A DE3345983C2 (en) 1983-12-20 1983-12-20 Method and device for the production of spherical metallic particles
DE3345983 1983-12-20

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EP0149027A2 EP0149027A2 (en) 1985-07-24
EP0149027A3 EP0149027A3 (en) 1987-09-02
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FR2657257B1 (en) * 1990-01-19 1994-09-02 Rhone Poulenc Sante PROCESS FOR THE PREPARATION OF DRUGS IN THE FORM OF PEARLS.
US5236466A (en) * 1991-08-30 1993-08-17 Chilean Nitrate Corporation Fast cooling of partially solidified granules of low melting, subliming substances obtained by prilling
US5558822A (en) * 1995-08-16 1996-09-24 Gas Research Institute Method for production of spheroidized particles
DE19821144A1 (en) * 1998-05-12 1999-11-18 Degussa Process for the production of powdery heterogeneous substances
US6228292B1 (en) * 1998-05-12 2001-05-08 Degussa Ag Process for the preparation of pulverulent heterogeneous substances
US6755886B2 (en) * 2002-04-18 2004-06-29 The Regents Of The University Of California Method for producing metallic microparticles
US7803210B2 (en) * 2006-08-09 2010-09-28 Napra Co., Ltd. Method for producing spherical particles having nanometer size, crystalline structure, and good sphericity
KR101168182B1 (en) * 2007-08-27 2012-07-24 보레알리스 테크놀로지 오와이. Equipment and process for producing polymer pellets
DE102013105369B4 (en) * 2013-05-24 2020-11-19 BinNova GmbH & Co. KG Method and device for the production of microfine fibers and filaments

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DE3345983C2 (en) 1986-09-04
ZA849879B (en) 1985-08-28
DD227355C4 (en) 1986-05-14
EP0149027A3 (en) 1987-09-02
AU571915B2 (en) 1988-04-28
ATE49146T1 (en) 1990-01-15
CA1235265A (en) 1988-04-19
DE3480909D1 (en) 1990-02-08
DE3345983A1 (en) 1985-06-27
JPS60135505A (en) 1985-07-18
AU3700084A (en) 1985-07-04
DD227355A5 (en) 1985-09-18
US4627943A (en) 1986-12-09
EP0149027A2 (en) 1985-07-24

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