EP0904171B1 - Dessiccation de poudre metallique atomisee - Google Patents

Dessiccation de poudre metallique atomisee Download PDF

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Publication number
EP0904171B1
EP0904171B1 EP97921034A EP97921034A EP0904171B1 EP 0904171 B1 EP0904171 B1 EP 0904171B1 EP 97921034 A EP97921034 A EP 97921034A EP 97921034 A EP97921034 A EP 97921034A EP 0904171 B1 EP0904171 B1 EP 0904171B1
Authority
EP
European Patent Office
Prior art keywords
liquid
container
pump
powder
protective gas
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP97921034A
Other languages
German (de)
English (en)
Other versions
EP0904171A1 (fr
Inventor
Rutger Larsson
Erik Axmin
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rutger Larson Konsult AB
Original Assignee
Rutger Larson Konsult AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Rutger Larson Konsult AB filed Critical Rutger Larson Konsult AB
Publication of EP0904171A1 publication Critical patent/EP0904171A1/fr
Application granted granted Critical
Publication of EP0904171B1 publication Critical patent/EP0904171B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • F26B21/06—Controlling, e.g. regulating, parameters of gas supply
    • F26B21/08—Humidity
    • F26B21/086—Humidity by condensing the moisture in the drying medium, which may be recycled, e.g. using a heat pump cycle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • F26B21/14—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects using gases or vapours other than air or steam, e.g. inert gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B5/00—Drying solid materials or objects by processes not involving the application of heat
    • F26B5/04—Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum

Definitions

  • the invention relates to a process for drying and possibly cooling atomized metal powder which is moist from a liquid used during the atomizing process, and which is surrounded by an atmosphere typical of manufacturing processes for metal powder, e.g. a substantially inert atmosphere, and equipment for performing the process.
  • a stream of molten metal is atomized with the aid of an atomizing agent.
  • the atomizing agent may be in gaseous or liquid form and may comprise a liquid hydrocarbon such as paraffin, fuel oil class 1, water or the like, for instance, in an environment substantially free from oxygen.
  • the powder formed falls down into a pool of coolant which may consist of the atomizing agent.
  • the powder is tapped to a transport container and the powder, usuall with increased temperature, e.g. 60-90°C, is then dried in a separate drying operation which constitutes an important part of the manufacturing process for many types of metal powder, particularly iron/steel powder having low oxygen content.
  • the powder is kept in a protective atmosphere (i.e. the typical atmosphere mentioned above or substantially inert atmosphere) until the risk has been substantially eliminated of the powder being adversely affected by the surrounding atmosphere.
  • a protective atmosphere i.e. the typical atmosphere mentioned above or substantially inert atmosphere
  • the moist powder is kept in an oxygen-free atmosphere of nitrogen, where the nitrogen may be of particularly oxygen-free quality in order to prevent oxidation.
  • the atomizing liquid is first allowed to run off the powder mass which is then tumbled by heated inert gas which is allowed to circulate through the tumbling powder mass so that the atomizing agent is vaporized and the vapour accompanying the inert gas is condensed and separated from the gas before the latter is recirculated.
  • the conventional technology has been found to require extensive and consequently expensive drying equipment, as well as entailing relatively high energy consumption.
  • the dried powder also has a high temperature which means that it must be cooled before it can be exposed to the surrounding atmosphere, and such powder cooling is expensive since it requires a cooling arrangement and since the thermal energy is cooled off.
  • An object of the invention is to provide a drying method that can be performed in a relatively simple apparatus and with relatively low energy consumption, preferably so that the dried powder immediately acquires a relatively low temperature and can preferably be immediately subjected to subsequent treatment, such as screening using conventional screening means.
  • the moist metal powder is contained in a container on a screening member disposed transversely in the container, that a vacuum is applied to the lower side of the screening member in order to draw off some of the liquid atomizing medium, that after the liquid has been drawn off, inert gas such as nitrogen gas, is circulated through the container in order to absorb residual moisture in the form of vapour from the powder mass, and that the vapour is removed from the gas forced through the container prior to recirculation in the container.
  • inert gas such as nitrogen gas
  • the liquid moistening the powder can be drawn off by means of a liquid jet pump (ejector pump).
  • ejector pump Such an ejector pump can also be used to subsequently withdraw vapour and gas from the container and to circulate the inert gas.
  • the ejector pump comprises a circulation circuit for the liquid driving the pump.
  • the driving liquid may consist entirely or partly of the atomizing medium used for manufacture of the powder.
  • the vapour sucked out by the pump is condensed in the liquid driving the ejector pump.
  • the liquid-circulation circuit of the ejector pump may also contain a heat exchanger allowing the circulating liquid to be heated or cooled.
  • the circulation circuit may also include a holding tank.
  • an upper gas space can be established in conventional manner, so that inert gas is permitted to separate from the liquid of the circulation circuit in the holding tank, and rises to the upper part of the holding tank so that inert gas can be conveyed for recirculation to the powder container.
  • the inert gas pipe may contain a heat exchanger to enable heating or cooling of the inert gas before it is reintroduced into the powder container.
  • a negative pressure is preferably established in the container in order to accelerate vaporization of the atomizing medium, whereby the temperature of the powder mass can also be reduced to a desired level.
  • the liquid can first be withdrawn from the container with the aid of a suitable liquid suction pump, such as a membrane pump. After which an ejector pump can be used as described above.
  • a suitable liquid suction pump such as a membrane pump.
  • a relatively "dense" cake may be formed on the screening member and according to one embodiment of the invention the cake is broken up in order to facilitate a flow of inert gas through the powder mass, thus facilitating drying of the powder.
  • An important feature of the invention is that the outflow, particularly the outflow of vapour from the container, is combined with the flow of driving liquid in an ejector pump so that the vapour leaving is condensed in the flow of driving liquid, while the inert gas can easily be separated for recirculation.
  • the drying process is initiated with suction of liquid atomizing medium from the powder mass, the residual moisture in the powder mass will be low and the energy required for the final drying process is reduced and thus also the heat of the powder itself (possibly in combination with a negative pressure) can provide the vaporization energy necessary for final drying. After final drying, therefore, the temperature of the powder is sufficiently low to enable additional cooling to be partly or entirely eliminated, which would otherwise be needed to prevent subsequent oxidation of the powder if exposed to the surrounding atmosphere.
  • Figure 1 shows a wet container 1 with a screening plate 2 disposed transversely in the container and carrying a metal powder mass 3.
  • a stirrer 4 is also shown schematically to break up the powder bed 3 if necessary.
  • the container has upper inlets 10, 14 and a lower outlet 12 with closing valves 11, 15 and 13, respectively.
  • the container 1 can be connected to a powder-atomizing plant and receives wet powder produced there via the inlet 14.
  • the closed container 1 can then be connected into a gas-circulation circuit 20, with valves 21, 22, as shown in the drawing.
  • the gas-circulation circuit 20 contains an inert gas such as nitrogen with a low content of oxygen and other damaging compounds.
  • the circuit 20 is supplied with inert gas from the gas source 23 as needed.
  • the circuit 20 includes a holding tank 25 for liquid atomizing medium, and a suction pump 30.
  • the suction pump e.g. an ejector pump, first withdraws liquid atomizing medium from the powder mass 3 and conveys this liquid to the holding tank 25.
  • the particle filter not shown, separates out any particles that may have accompanied the liquid.
  • the holding tank 25 has an upper space 26 which thus contains inert gas.
  • the tank 25 naturally also contains a mass 27 of liquid atomizing medium and this liquid mass 27 can be kept at a constant level by means known per se.
  • the liquid atomizing medium is circulated from the tank 25 via a pump 60 and a cooler 61 to the ejector pump 30, causing this to produce a negative pressure in the outlet side of the container 1.
  • the quantity of liquid in the powder can be reduced to an optimally low proportion by means of suction and the residual moisture departs in the form of vapour, to the gas flow circulating in the circuit 20 with the aid of the pump 30.
  • the vapour accompanying the gas flow is condensed in the cooled atomizing liquid circulating through the circulation circuit 70.
  • the partial pressure in the lower side of the container 1 facilitates vaporization of the remaining liquid in the powder mass 3, as well as lowering the temperature of the powder mass 3.
  • a heater 80 may be connected in the gas-circulation circuit 20 upstream of the container 1, if the powder itself is not sufficiently hot to vaporize the remaining moisture at the prevailing pressure.
  • the drawing shows an ejector pump 30 both for removal of liquid and circulation of gas.
  • a liquid suction pump e.g. a membrane pump
  • the ejector pump 30 may be replaced by another type of pump for circulating the gas.
  • gas-circulation circuit and the liquid-circulation circuit have a common section so that vapour accompanying the gas flow is condensed in the liquid, preferably cooled, and that the gas circuit and liquid circuit are preferably joined via an ejector pump.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Molecular Biology (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)
  • Drying Of Solid Materials (AREA)
  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)

Claims (9)

  1. Procédé de dessiccation d'une poudre métallique atomisée contenue dans une atmosphère protectrice et humidifiée par un liquide utilisé pendant le processus d'atomisation, la poudre métallique humidifiée (3) étant logée dans un récipient (1), et la vapeur étant séparée du gaz protecteur circulant dans le récipient avant une recirculation dans le récipient,
    caractérisé en ce que la poudre métallique (3) est contenue sur un élément de tamisage (2) disposé transversalement dans le récipient, en ce qu'un vide est appliqué au côté inférieur de l'élément de tamisage (2) pour soutirer une partie du liquide, et en ce qu'une fois que le liquide a été soutiré, on fait circuler un gaz protecteur dans le récipient pour absorber le liquide vaporisé, à partir de la masse de poudre.
  2. Procédé selon la revendication 1, caractérisé en ce que le liquide est soutiré au moyen d'une pompe aspirante telle qu'une pompe à membrane.
  3. Procédé selon la revendication 1 ou la revendication 2, caractérisé en ce qu'une pompe à jet de liquide (30) est raccordée à la partie inférieure du récipient (1) pour établir une dépression au-dessous de l'élément de tamisage (2), et en ce que la pompe à liquide est entraínée par un écoulement de liquide circulant, la vapeur se condensant dans l'écoulement de liquide circulant de la pompe d'éjecteur, ledit écoulement étant constitué en partie ou en totalité par le liquide avec lequel la poudre a été humidifiée.
  4. Procédé selon la revendication 3, caractérisé en ce que le circuit de circulation du liquide de la pompe (30) comprend un réservoir de retenue (25), qui est maintenu seulement partiellement rempli de liquide de manière à permettre une séparation du gaz protecteur accompagnant le liquide en circulation, ledit gaz étant prélevé du réservoir de retenue et introduit en circulation dans le récipient.
  5. Procédé selon l'une quelconque des revendications 1-4, caractérisé en ce que le courant de gaz protecteur est chauffé (80) avant d'être envoyé au récipient (1) contenant la poudre.
  6. Procédé selon l'une quelconque des revendications 1-5, caractérisé en ce que l'on casse (4) le gâteau constitué par la masse de poudre humide (3) formé sur l'élément de tamisage (2) lors du retrait du liquide pour faciliter la circulation du gaz protecteur à travers la masse de poudre.
  7. Equipement de dessiccation d'une poudre métallique atomisée contenue dans une atmosphère protectrice à l'intérieur d'un récipient (1) et humidifiée par un liquide utilisé pendant le processus d'atomisation,
    caractérisé en ce que la poudre métallique humide (3) présente dans le récipient (1) repose sur un élément de tamisage (2) disposé transversalement dans le récipient, en ce que le récipient comprend un élément formant pompe (30) servant à entraíner le liquide à partir de la masse de poudre (3), et en ce que l'élément formant pompe est agencé de manière à faire circuler le gaz protecteur à travers le récipient (1) pour entraíner la vapeur extraite de la masse de poudre, et en ce que des condenseurs (25, 26, 27) sont disposés de manière à condenser la vapeur accompagnant le gaz protecteur de sorte que le gaz protecteur est essentiellement libéré de la vapeur avant d'être renvoyé en circulation au récipient (1).
  8. Equipement selon la revendication 7, caractérisé en ce que l'élément formant pompe comprend un circuit de circulation (70) pour un liquide, en ce que les parties supérieure et inférieure du récipient (1) sont raccordées à un circuit de circulation (20) pour le gaz protecteur, en ce que les deux circuits (20, 70) se rejoignent au niveau de l'élément formant pompe, qui se présente sous la forme d'une pompe à jet de liquide (30), de sorte que la vapeur accompagnant le gaz protecteur est condensée dans le circuit de condensation de liquide (70) de l'élément formant pompe.
  9. Equipement selon la revendication 8, caractérisé en ce que le liquide contenu dans le circuit de circulation du liquide de la pompe à jet de liquide est constitué entièrement ou partiellement par le liquide avec lequel la poudre a été humidifiée.
EP97921034A 1996-04-18 1997-04-18 Dessiccation de poudre metallique atomisee Expired - Lifetime EP0904171B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE9601481A SE509031C2 (sv) 1996-04-18 1996-04-18 Torkning av atomiserat metallpulver
SE9601481 1996-04-18
PCT/SE1997/000655 WO1997038812A1 (fr) 1996-04-18 1997-04-18 Dessiccation de poudre metallique atomisee

Publications (2)

Publication Number Publication Date
EP0904171A1 EP0904171A1 (fr) 1999-03-31
EP0904171B1 true EP0904171B1 (fr) 2001-07-18

Family

ID=20402253

Family Applications (1)

Application Number Title Priority Date Filing Date
EP97921034A Expired - Lifetime EP0904171B1 (fr) 1996-04-18 1997-04-18 Dessiccation de poudre metallique atomisee

Country Status (6)

Country Link
EP (1) EP0904171B1 (fr)
AU (1) AU2718697A (fr)
CA (1) CA2251752C (fr)
DE (1) DE69705715T2 (fr)
SE (1) SE509031C2 (fr)
WO (1) WO1997038812A1 (fr)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000063671A1 (fr) * 1999-04-17 2000-10-26 Genevac Limited Evaporation de liquides et recirculation de gaz purifie
US20150260454A1 (en) * 2014-03-12 2015-09-17 Ut-Battelle Llc Adsorbed water removal from titanium powders via water activation
EP3504020B1 (fr) 2016-08-24 2023-04-19 5n Plus Inc. Procédés de fabrication par atomisation de poudres de métal ou d'alliage à bas point de fusion
US11084095B2 (en) 2018-02-15 2021-08-10 5N Plus Inc. High melting point metal or alloy powders atomization manufacturing processes
CN111300655A (zh) * 2020-02-24 2020-06-19 中国水利水电第五工程局有限公司 一种双压循环砂仓砂料加速脱水方法
CN113913797A (zh) * 2021-09-17 2022-01-11 金华职业技术学院 一种化学镀粉末烘干保护的方法

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ZA785312B (en) * 1977-09-22 1979-08-29 Davy Loewy Ltd Production of metal powder
CA2038449C (fr) * 1990-03-20 1999-03-16 Naotsugu Isshiki Methode de production de poudre metallique et appareil connexe

Also Published As

Publication number Publication date
DE69705715D1 (de) 2001-08-23
WO1997038812A1 (fr) 1997-10-23
CA2251752A1 (fr) 1997-10-23
AU2718697A (en) 1997-11-07
EP0904171A1 (fr) 1999-03-31
SE9601481L (sv) 1997-10-19
CA2251752C (fr) 2005-08-02
DE69705715T2 (de) 2002-06-13
SE509031C2 (sv) 1998-11-30
SE9601481D0 (sv) 1996-04-18

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