EP0904171B1 - Trocknung von atomisierten metallpulvern - Google Patents
Trocknung von atomisierten metallpulvern Download PDFInfo
- 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
Links
Images
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)
- Verfahren zum Trocknen zerstäubten Metallpulvers, das in einer Schutzatmosphäre enthalten und von einer während des Zerstäubungsvorgangs verwendeten Flüssigkeit feucht ist, bei dem das feuchte Metallpulver (3) in einem Behälter (1) enthalten ist und dass Dampf vom durch den Behälter zirkulierenden Schutzgas vor einer Rückführung in den Behälter abgetrennt wird, dadurch gekennzeichnet, dass sich das Metallpulver (3) auf einem in dem Behälter quer angeordneten Trennelement (2) befindet, dass auf der Unterseite des Trennelements (2) ein Vakuum angelegt wird, um einiges der Flüssigkeit abzuziehen, dass eine Zirkulation von Schutzgas, nachdem die Flüssigkeit abgezogen wurde, durch den Behälter stattfindet, um verdampfte Flüssigkeit von der Pulvermenge zu absorbieren.
- Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die Flüssigkeit mittels einer Saugpumpe, wie einer Membranpumpe, abgezogen wird.
- Verfahren nach Anspruch 1 oder Anspruch 2, dadurch gekennzeichnet, dass eine Flüssigkeitsstrahlpumpe (30) an den unteren Teil des Behälters (1) angeschlossen ist, um unter dem Trennelement (2) einen Unterdruck aufzubauen, und dass die Flüssigkeitspumpe von einem zirkulierenden Flüssigkeitsstrom angetrieben wird, der den Dampf im zirkulierenden Flüssigkeitsstrom der Ejektorpumpe kondensiert, sowie der Strom teilweise oder vollständig aus der Flüssigkeit besteht, mit der das Pulver angefeuchtet war.
- Verfahren nach Anspruch 3, dadurch gekennzeichnet, dass der Flüssigkeitszirkulationskreis der Pumpe (30) einen Aufbewahrungstank (25) umfasst, der nur teilweise mit Flüssigkeit gefüllt gehalten wird, um eine Trennung des die Zirkulationsflüssigkeit begleitenden Schutzgases zu ermöglichen, wobei das Gas aus dem Aufbewahrungstank abgezogen wird und eine Zirkulation zum Behälter stattfindet.
- Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass der Schutzgasstrom erwärmt (80) wird, bevor dieser zum Pulverbehälter (1) zurückgeführt wird.
- Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass der auf dem Trennelement (2) beim Abziehen der Flüssigkeit gebildete Kuchen aus feuchter Pulvermenge (3) zerbrochen wird (4), um eine Zirkulation des Schutzgases durch die Pulvermenge zu erleichtern.
- Vorrichtung zum Trocknen zerstäubten Metallpulvers, das in einer Schutzatmosphäre in einem Behälter (1) enthalten und von einer während des Zerstäubungsvorgangs verwendeten Flüssigkeit feucht ist, dadurch gekennzeichnet, dass das feuchte Metallpulver (3) im Behälter (1) sich auf einem quer im Behälter angeordneten Trennelement (2) befindet, dass die Vorrichtung ein Pumpenelement (30) zum Abziehen von Flüssigkeit aus der Pulvermenge (3) umfasst und dass das Pumpenelement so angeordnet ist, dass Schutzgas durch den Behälter (1) zirkuliert, um den von der Pulvermenge abgezogenen Dampf mitzunehmen, und dass Kondensatoren (25, 26, 27) zum Kondensieren des das Schutzgas begleitenden Dampfes vorgesehen sind, so dass das Schutzgas im Wesentlichen vom Dampf befreit ist, bevor es zum Behälter (1) zurückgeführt wird.
- Vorrichtung nach Anspruch 7, dadurch gekennzeichnet, dass das Pumpenelement einen Zirkulationskreis (70) für eine Flüssigkeit umfasst, dass die oberen und unteren Teile des Behälters (1) mit einem Zirkulationskreis (20) für das Schutzgas verbunden sind, dass beide Kreise (20, 70) sich beim Pumpenelement, das vom Typ einer Flüssigkeitsstrahlpumpe (30) ist, verbinden, so dass der das Schutzgas begleitende Dampf im Flüssigkeitszirkulationskreis (70) des Pumpenelements kondensiert.
- Vorrichtung nach Anspruch 8, dadurch gekennzeichnet, dass die Flüssigkeit im Flüssigkeitszirkulationskreis der Flüssigkeitsstrahlpumpe vollständig oder teilweise aus der Flüssigkeit besteht, mit der das Pulver befeuchtet war.
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 (en) | 1996-04-18 | 1997-04-18 | Drying of atomized metal powder |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0904171A1 EP0904171A1 (de) | 1999-03-31 |
EP0904171B1 true EP0904171B1 (de) | 2001-07-18 |
Family
ID=20402253
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP97921034A Expired - Lifetime EP0904171B1 (de) | 1996-04-18 | 1997-04-18 | Trocknung von atomisierten metallpulvern |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP0904171B1 (de) |
AU (1) | AU2718697A (de) |
CA (1) | CA2251752C (de) |
DE (1) | DE69705715T2 (de) |
SE (1) | SE509031C2 (de) |
WO (1) | WO1997038812A1 (de) |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2000063671A1 (en) * | 1999-04-17 | 2000-10-26 | Genevac Limited | Evaporation of liquids and recirculation of purified gas |
US20150260454A1 (en) * | 2014-03-12 | 2015-09-17 | Ut-Battelle Llc | Adsorbed water removal from titanium powders via water activation |
EP3504020B1 (de) | 2016-08-24 | 2023-04-19 | 5n Plus Inc. | Pulverzerstäubungsherstellungsverfahren mit metallen oder legierungen mit niedrigem schmelzpunkt |
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)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
ZA785312B (en) * | 1977-09-22 | 1979-08-29 | Davy Loewy Ltd | Production of metal powder |
CA2038449C (en) * | 1990-03-20 | 1999-03-16 | Naotsugu Isshiki | Method of and apparatus for producing metal powder |
-
1996
- 1996-04-18 SE SE9601481A patent/SE509031C2/sv not_active IP Right Cessation
-
1997
- 1997-04-18 AU AU27186/97A patent/AU2718697A/en not_active Abandoned
- 1997-04-18 DE DE69705715T patent/DE69705715T2/de not_active Expired - Lifetime
- 1997-04-18 EP EP97921034A patent/EP0904171B1/de not_active Expired - Lifetime
- 1997-04-18 WO PCT/SE1997/000655 patent/WO1997038812A1/en active IP Right Grant
- 1997-04-18 CA CA002251752A patent/CA2251752C/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
DE69705715D1 (de) | 2001-08-23 |
WO1997038812A1 (en) | 1997-10-23 |
CA2251752A1 (en) | 1997-10-23 |
AU2718697A (en) | 1997-11-07 |
EP0904171A1 (de) | 1999-03-31 |
SE9601481L (sv) | 1997-10-19 |
CA2251752C (en) | 2005-08-02 |
DE69705715T2 (de) | 2002-06-13 |
SE509031C2 (sv) | 1998-11-30 |
SE9601481D0 (sv) | 1996-04-18 |
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