US3671220A - Process for the production of powdered metals - Google Patents

Process for the production of powdered metals Download PDF

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Publication number
US3671220A
US3671220A US35991A US3671220DA US3671220A US 3671220 A US3671220 A US 3671220A US 35991 A US35991 A US 35991A US 3671220D A US3671220D A US 3671220DA US 3671220 A US3671220 A US 3671220A
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temperature
metal
gas
reaction
mixture
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Expired - Lifetime
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US35991A
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English (en)
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Kurt Alfred Jonsson
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Rederi Nordstjernan AB
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Rederi Nordstjernan AB
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Priority claimed from SE04529/70A external-priority patent/SE333815B/xx
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B5/00—General methods of reducing to metals
    • C22B5/02—Dry methods smelting of sulfides or formation of mattes
    • C22B5/16—Dry methods smelting of sulfides or formation of mattes with volatilisation or condensation of the metal being produced
    • 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
    • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
    • B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
    • B22F9/28—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from gaseous metal compounds
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/02—Making non-ferrous alloys by melting

Definitions

  • An apparatus and process are provided for reducing metal halides to metal powder low in halide content, the process comprising providing a preheated substantially uniform mixture of reactants comprising a metal halide uniformly dispersed through hydrogen at a temperature above the reaction temperature for said reactants,- and then immediately feeding the preheated mixture into a reaction chamber, whereby the reaction to metal powder is substantially spontaneously effected.
  • This invention relates to a process and apparatus for the production of metal powders by the reduction of metal halides and, in particular, to the production of such metal powders as tungsten, molybdenum, tantalum, nio bium, rhenium, chromium and alloys thereof.
  • Another known process comprises applying metal coatings to objects such as tungsten or molybdenum coatings.
  • the gaseous reactants are mixed in a single tube with the conditions of reduction chosen to occur at the surface of the object to be coated.
  • the gas mixture is maintained at below the reaction temperature while the object is heated, e.g. inductively heated, to a temperature above the reaction temperature of the mixture to effect reduction at the surface of the object.
  • the object is not to form metal powder but to reduce out a metallic coat on the surface of objects.
  • the present process differs in that metal powder of the desired grain size low in residual halide content can be produced by using less hydrogen than is normally employed in prior art processes.
  • Another object of the invention is to provide a process for producing metal powder from metal halides, such as chlorides of tungsten, molybdenum, tantalum, niobium, rhenium, chromium, and the like, by reduction with hydrogen with the following advantages: (1) control of grain size of the resulting metal powder; (2) use of lower amounts of hydrogen; (3) inhibition of metal foil formation on reactor walls, in feed lines and at the nozzles; and (4) production of metal powder with a low residual halide content.
  • metal halides such as chlorides of tungsten, molybdenum, tantalum, niobium, rhenium, chromium, and the like
  • FIG. 1 is a schematic representation of one apparatus embodiment-for carrying out the invention.
  • FIG. 2 is afragment in cross section of a mixing tube.
  • a process for reducing metal halides to metal powder low in residual halide content comprising, providing a preheated substantially unreacted mixture of reactants comprising a metal halide uniformly dispersed through hydrogen preheated to a temperature at least above the reaction temperature for said mixed reactants, and then immediately feeding the preheated mixture into the reaction chamber, whereby the reaction to metal powder is substantially spontaneously effected.
  • the reduction process is carried out in the 'presence of hydrogen in such a manner that the chlorides, in preferably the gaseous state, are mixed with hydrogen in one or several ducts at a first temperature above the reaction temperature before the mixture is fed into the reactor, the preheated mixture being thereafter directed at a predetermined or controlled velocity into the reactor which is preferably, though not necessarily, heated to a second temperature above the first temperature
  • the resulting metal powder is then separated from the gas.
  • the desired grain size of the powder product is determined by controlling one or more variables of the gas mixture, such as the temperature, the velocity of the gaseous reactants, the ratio of the reactants, etc.
  • the apparatus employed for carrying out the process preferably utiliz'es a metal mixing tube which extends into the reactor, the apparatus being provided with means for adjusting the ratio of the mixture, the velocity of the mixture, the
  • FIG. 1 shows a reactor 1 provided with a plurality of electric heating elements 2, the heating elements being divided in groups (known in the art) so that the thermal energy is supplied in a series of zones.
  • a metal mixing duct 3 is provided which opens into the reactor, the mixing tube extending sufficiently inwardly from reactor end wall 1A in order to avoid reaction between the halide gas and the reduction gas at the end wall.
  • the metal duct preferably is mounted coaxially 'With the longitudinal axis of the reactor.
  • the reactor may also be provided with several mixing ducts for the supply of mixed gas.
  • the ducts are preferably introduced into the reactor near or about the line of symmetry or longitudinal axis of the reactor and in parallel with said axis.
  • the reaction components in the gaseous state and possibly another gas are supplied to the mixing tube through feed lines.
  • the drawing shows a line 4 for the supply of metal halides in preferably the gaseous phase, a second line 5 being provided for sup.- plying reduction gas (e.g. hydrogen), and a third line 6 for supplying, when desired, an inert gas, or a halogen in gaseous state or some other gas.
  • a plurality of heating are t a e m ned. at ,.tem e tur d velocity such that a powder of a desired grain size is obtained.
  • the gas velocity should be selected relative to the length of the mixing tube so that there is sufficient time for only a slight reaction to begin within the mixing tubeiprior'tothe entry of the gas into the reactor.
  • the reaction incubatesinthe mixing tube just before it enters there'action zone in the reaction charnber, Subsequent to the-entry thereof into the reactor, the gasm'ixture satisfies all conditions required for a continued reaction, which takes place very rapidly and completely in the reactor which preferably, though not necessarily, is maintained at a higher temperature than the temperature in the mixing tube.
  • the metal powder obtained according to conventional processes in which substantial excess of hydrogen is employed usually is much too fine-grained, and, in most cases, falls within the grain size range from about 0.01 to 0.05 micron with the density between about 0.15 and 0.35 g./cm.
  • the range whichvis of interest in commerce, however,, lies between 0.05 and 10 microns, and the densities of interest are froni 0.8 to 4 g./cm.
  • powder may be obtained which falls within the aforementioned desired ranges.
  • the ratio of mixture of reduction gas and halide gas affects the grain size inthat an increase in the reduction gas content results in decreasing grain size.
  • asmall grain size can be elements are shown at 7 for possibly supplying heat to the gas. These elements are arranged around the mixing tube in heat transfer relationship therewith in the conventional manner. Means 8 are provided for cooling the gas mixture to the desired first temperature where this, is found necessary.
  • a thermocouple for measuring the temperature of the gas mixture before it enters the reactor. The thermocouple is mounted immediately before the place of entry as it has been found to be a suitable point for temperature measurement.
  • Vibratory means 10 are provided for vibrating the mixing tube, the means being preferably attached immediately before the point of entry of the mixing tube into the reactor By subjecting the mixing tube to vibration, it is possible to inhibit metal reduced out from depositing on the orifiec of the mixing tube in the reactor.
  • the shape of the orifice of the mixing tube in the reactor is shown in'FIG. 2, where the annulus of the tube is pointed or tapered so as to provide a sharp edge, to further avoid adhesion of the metal reduced out.
  • the halide. gas and the reduction gas are mixed in one. or several tubes prior to being fed into the reactor at a temperature exceeding the reaction temperature of the gas mixture.
  • the conditions for a reaction already prevail within the mixing tube, and that the reaction is beginning to commerce here. However, it is not desirable that the reaction proceed to any great extent within the mixing tube.
  • the primary objective is to effect a highly homogeneous mixture and, secondly, to produce a mixture in which the reactants achieved with a relatively small excess of reduction gas which, in the case of hydrogen, usually does not exceed twice the stoichiometric amount required for the reaction. This is advantageous in that provides an economic process.
  • the temperature affects the grain size such that with increasing temperature of the mixing gas, a. decrease in grain size is obtained.
  • the grain size in the powder may be decreased more substantially by adding a halogen (e.g. chlorine) ,in the gaseous state to the gas mixture. This is because an indirect temperature increase results by the reaction of the halogen gas with excess hydrogen.
  • a halogen e.g. chlorine
  • thehydrogen gas and the metal halide e.g. chloride
  • gases are heated or cooled in advance to a temperature within the desired temperature range.
  • Around the mixing tube may then be supplied extra heating or cooling means for slightly adjusting the temperature of the mixing gas to the desired range prior to the entry thereof into the reactor.
  • Another method of rapidlyadjusting the temperature of the mixing gas is by-dilution withan inert gas, such as nitrogen gas or hydrogen chloride. Such a dilution of the mixing gas results in a powder of a greater-grain size.
  • reaction-in the reactor proceeds efiiciently to completion, whereby the produced powder has a very low chlorine content, in many cases below 0.5%.
  • a further advantage is the highly improved quality of the powder, due to the absence of inhomogeneity 'in theform of flakes or glittering foils. It is generallydesirable to'raise the temperature in thelower reactor part by an additional supply of heat in order to assure completeness of the reaction.
  • the apparatus for carrying out the process comprises substantially a mixing tube extending into a reaction chamber.
  • mixing tubes preferably are oriented 1 along the line of symmetry'or longitudinal axis of the more, preferably open within the reactor some distance inside from its inner wall.
  • the mixing tubes preferably are made of a metal. If the temperature of thegas mixture can be maintained below 600 C., tubes of nickel or Inconel Cr. 6 to 7% 'Fe and'theb'alance nickel) may be used without giving rise to aggravated corrosion problems which usually. contaminated the powder to an appreciable degree. Previously, tubes of glass or quartz have been used, but such tubes had a very short life and, moreover, they contaminated the metal'powder when they boke into pieces.
  • Tubes made of metal are advantageous also in other respects. They can be subjected to vibrations, so that possible incrustations .on thetube can easily be removed by shaking. This'can be effected very simply by placing a vibrator on the mixing tube immediately before its entry into the reactor.
  • the tube mouth in order to prevent metal reduced out from adhering on the tube mouth in the reactor, the tube mouth preferably is pointed so as to form a shap edge. It is also easy to supply or remove heat through the metal tube, which facilitates controlling the temperature of the gas mixture.
  • Example 1 Utilizing an apparatus of the type shown in FIG. 1, a fiow of 22 kg. WCl per hour was mixed with a flow of 96 litres of H per minute (referred to room temperature) in a nickel tube opening into the reactor heated to 1000 C.
  • the WCl gas had a temperature of 400 C., and the H gas of 525 C. This resulted in a mixture which immediately prior to its entry into the furnace had a temperature of about 440 C., since a certain amount of heat transfer between the mixing tube and the ambient environment had thereby taken place.
  • the gas velocity was 25 m./sec.
  • the tungsten powder produced had a residual chlorine content of about 0.26% by weight and a grain size of about 0.2 micron determined by means of an electron microscope.
  • the density of the powder was 1.32 g./cm.
  • the powder did not contain glittering metal fragments and was uniform, the inside of the mixing tube being free of metal coatings.
  • Example 2 A flow of 22 kg. WC1 per hour was mixed as in Example 1 with a fiow of 70 litres of H per minute (referred to room temperature) in a nickel tube into the reactor.
  • the upper portion of the reactor was heated to 800 C., the central portion to 900 C., and the lower portion to 1000 C.
  • the WCl gas had a temperature of 400 C., and the H gas a temperature of 150 C. This resulted in a mixture which immediately prior to its entry into the furnace had a temperature of about 320 C.
  • the gas velocity was about 16 m./ sec.
  • the tungsten powder produced had a residual chlorine content of about 0.8% by weight and a grain size of 2.1 microns determined by means an electron microscope. The density was 3.2 g./cm. The powder did not contain glittering fragments and was uniform. The inside of the mixing tube was free of metal coatings.
  • Example 3 Utilizing an apparatus of the type shown in FIG. 1, a flow of 13 kg. WC1 per hour and 3.0 kg. C1 per hour was mixed with a flow of nitrogen gas of 96 litres/min. (referred to room temperature) in a nickel tube opening into the reactor heated to 1110 C.
  • the mixture of WCl and C1 had a temperature of about 400 C.
  • the temperature of the gas mixture was 415 C. immediately prior to the entry into the furnace.
  • the gas velocity was 60 m./sec.
  • the tungsten powder produced had a residual chlorine content of about 0.5% and a grain size of about 0.05 micron determined by means of an electron microscope. The powder did not contain glittering fragments and was uniform.
  • the inside of the mixing tube was free of metal coatings.
  • reaction of other halides may be carried out similar to Examples 1, 2 and 3.
  • the amount of hydrogen which may be employed in carrying out the reaction need not exceed two times the stoichiometric amount.
  • the grain size can be controlled according to the amount of hydrogen used, that is, the greater the amount of hydrogen, the smaller the grain size.
  • the higher the mixing temperature of the unreacted ingredients the smaller the ultimate grain size.
  • the addition of a halogen to the gas mixture also results in a decrease in grain size. Larger grains may be produced by inversely controlling one or more of the foregoing variables, that is, by lowering the temperature, or lowering the ratio of hydrogen to the halide, etc., or by adding an inert gas or HCl.
  • the temperature of the reactor in each of the examples is higher than the mixing temperature of the reactants, the reactor temperature need not be higher so long as the reaction goes to completion therein and so long as the temperature of the substantially unreacted premixed ingredients fed to the reactor is above the reaction temperature.
  • the temperature in the reactor is usually higher than the temperature of the unreacted gas mixture fed to it.
  • the temperature in the reactor may range up to about 1600 C. and, for example, from about 700 C. or 800 C. to 1600 C.
  • the minimum reaction temperature of a particular mixture of metal halide and hydrogen can be determined by tests. For example, tests have shown that heating WCl in a quartz tube furnace under a low hydrogen flow indicated that the minimum reaction temperature in this system ranged from about 300C .to 330 C.
  • a process for reducing metal halides to metal powder low in halide content which comprises,
  • reaction to metal powder is substantially spontaneously effected in said reaction chamber.
  • metal halides are selected from the group consisting of halides of W, Mo, Ta, Nb, Re, Cr and mixtures thereof.
  • the gr'ain' size of the ultimate metal powder is determined by controlling at least one of the parameters: ratio of the reactants, velocity of the reactant mixture, the temperature of the mixture, and the amount of gaseous diluent selected from the group consisting of inert gases and 'a halogen added'to the reactant mixture; such that for increased amounts of hydrogen or increased velocity, or increased temperature of the mixture, a finer grain size is obtained, and'where at least one of the foregoing parameters is decreased, a larger grain size is obtained; and such that when an inert gas is added to the mixture, a larger grain size is obtained, and when a halogen is added to the mixture, a finer grain size is obtained.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)
  • Manufacture And Refinement Of Metals (AREA)
US35991A 1969-05-19 1970-05-11 Process for the production of powdered metals Expired - Lifetime US3671220A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE700369 1969-05-19
SE04529/70A SE333815B (enrdf_load_stackoverflow) 1970-04-02 1970-04-02

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US (1) US3671220A (enrdf_load_stackoverflow)
JP (1) JPS5031554B1 (enrdf_load_stackoverflow)
BE (1) BE750580A (enrdf_load_stackoverflow)
CS (1) CS150507B2 (enrdf_load_stackoverflow)
DE (1) DE2023958B2 (enrdf_load_stackoverflow)
FR (1) FR2048525A5 (enrdf_load_stackoverflow)
GB (1) GB1284178A (enrdf_load_stackoverflow)
NL (1) NL7007230A (enrdf_load_stackoverflow)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3723601A (en) * 1970-05-27 1973-03-27 Nordstjernan Rederi Ab Method of producing refractory metals and refractory metal compounds in powder form
US3773493A (en) * 1971-12-22 1973-11-20 Westinghouse Electric Corp Method of producing doped tungsten powders by chemical deposition
US3851136A (en) * 1971-11-20 1974-11-26 Max Planck Gesellschaft Process and equipment for the treatment of a material by means of an arc discharge plasma
US4383852A (en) * 1980-09-13 1983-05-17 Toho Aen Kabushiki Kaisha Process for producing fine powdery metal
US4526610A (en) * 1982-04-02 1985-07-02 Toyota Jidosha Kabushiki Kaisha Metal cored ceramic surfaced fine powder material and apparatus and method for making it
US4556416A (en) * 1983-05-07 1985-12-03 Sumitomo Electric Industries, Ltd. Process and apparatus for manufacturing fine powder
EP0978338A4 (en) * 1998-02-20 2004-11-24 Toho Titanium Co Ltd PROCESS FOR PRODUCING NICKEL POWDER
US20050097991A1 (en) * 2003-09-19 2005-05-12 Angel Sanjurjo Methods and apparatuses for producing metallic compositions via reduction of metal halides
CN113020617A (zh) * 2021-02-26 2021-06-25 宁夏德运创润钛业有限公司 一种制备超细微高纯难熔金属粉末的方法

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2523009B1 (fr) * 1982-03-11 1987-01-02 Toho Zinc Co Ltd Procede de production de metaux en poudres fines
JPS59170211A (ja) * 1983-03-14 1984-09-26 Toho Aen Kk 超微粉の製造方法
DE4214719C2 (de) * 1992-05-04 1995-02-02 Starck H C Gmbh Co Kg Verfahren zur Herstellung feinteiliger Metall- und Keramikpulver
DE4214720C2 (de) * 1992-05-04 1994-10-13 Starck H C Gmbh Co Kg Vorrichtung zur Herstellung feinteiliger Metall- und Keramikpulver

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3723601A (en) * 1970-05-27 1973-03-27 Nordstjernan Rederi Ab Method of producing refractory metals and refractory metal compounds in powder form
US3851136A (en) * 1971-11-20 1974-11-26 Max Planck Gesellschaft Process and equipment for the treatment of a material by means of an arc discharge plasma
US3773493A (en) * 1971-12-22 1973-11-20 Westinghouse Electric Corp Method of producing doped tungsten powders by chemical deposition
US4383852A (en) * 1980-09-13 1983-05-17 Toho Aen Kabushiki Kaisha Process for producing fine powdery metal
US4526610A (en) * 1982-04-02 1985-07-02 Toyota Jidosha Kabushiki Kaisha Metal cored ceramic surfaced fine powder material and apparatus and method for making it
US4556416A (en) * 1983-05-07 1985-12-03 Sumitomo Electric Industries, Ltd. Process and apparatus for manufacturing fine powder
EP0978338A4 (en) * 1998-02-20 2004-11-24 Toho Titanium Co Ltd PROCESS FOR PRODUCING NICKEL POWDER
US20050097991A1 (en) * 2003-09-19 2005-05-12 Angel Sanjurjo Methods and apparatuses for producing metallic compositions via reduction of metal halides
US7559969B2 (en) * 2003-09-19 2009-07-14 Sri International Methods and apparatuses for producing metallic compositions via reduction of metal halides
CN113020617A (zh) * 2021-02-26 2021-06-25 宁夏德运创润钛业有限公司 一种制备超细微高纯难熔金属粉末的方法

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Publication number Publication date
GB1284178A (en) 1972-08-02
FR2048525A5 (enrdf_load_stackoverflow) 1971-03-19
NL7007230A (enrdf_load_stackoverflow) 1970-11-23
BE750580A (fr) 1970-11-03
CS150507B2 (enrdf_load_stackoverflow) 1973-09-04
DE2023958A1 (de) 1970-11-26
JPS5031554B1 (enrdf_load_stackoverflow) 1975-10-13
DE2023958B2 (de) 1973-01-11

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