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WO1993014023A1 - Procede de production d'une poudre constituee de particules fines et installation pour sa mise en ×uvre - Google Patents

Procede de production d'une poudre constituee de particules fines et installation pour sa mise en ×uvre Download PDF

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Publication number
WO1993014023A1
WO1993014023A1 PCT/DK1993/000001 DK9300001W WO9314023A1 WO 1993014023 A1 WO1993014023 A1 WO 1993014023A1 DK 9300001 W DK9300001 W DK 9300001W WO 9314023 A1 WO9314023 A1 WO 9314023A1
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WO
WIPO (PCT)
Prior art keywords
aerosol
chamber
powder
droplets
gas
Prior art date
Application number
PCT/DK1993/000001
Other languages
English (en)
Inventor
Ebbe Skyum JØNS
Svend Danielsen
Original Assignee
Niro Holding A/S
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 Niro Holding A/S filed Critical Niro Holding A/S
Publication of WO1993014023A1 publication Critical patent/WO1993014023A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
    • C01B13/14—Methods for preparing oxides or hydroxides in general
    • C01B13/34—Methods for preparing oxides or hydroxides in general by oxidation or hydrolysis of sprayed or atomised solutions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D1/00—Evaporating
    • B01D1/16—Evaporating by spraying
    • B01D1/18—Evaporating by spraying to obtain dry solids
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
    • C01B13/14—Methods for preparing oxides or hydroxides in general
    • C01B13/18—Methods for preparing oxides or hydroxides in general by thermal decomposition of compounds, e.g. of salts or hydroxides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G23/00—Compounds of titanium
    • C01G23/003—Titanates
    • C01G23/006—Alkaline earth titanates
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G3/00—Compounds of copper
    • C01G3/006—Compounds containing copper, with or without oxygen or hydrogen, and containing two or more other elements
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G37/00—Compounds of chromium
    • C01G37/006—Compounds containing chromium, with or without oxygen or hydrogen, and containing two or more other elements
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/03—Particle morphology depicted by an image obtained by SEM
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/30—Particle morphology extending in three dimensions
    • C01P2004/32—Spheres
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/51—Particles with a specific particle size distribution
    • C01P2004/52—Particles with a specific particle size distribution highly monodisperse size distribution
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/10—Solid density
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area

Definitions

  • the present invention relates to the ' manufacture of a powder of substantially spherical mono-particles of desired components consisting of inorganic salts or oxides or of organic compounds, metals or mixtures thereof. Such powders of submicron particle size or of a median particle size of a few microns are useful in various technological fields.
  • Metal powders of such small size are useful as sintering aids facilitating the sintering of more coarse sinter powders.
  • a commercial interest also exists for wax powders having a median particle diameter of 3-5 microns.
  • the main interest in fine powders of the type dealt with in the present applica- tion is within the high technological ceramic industry, and in the following the invention is primarily de ⁇ scribed in connection with ceramic powders of submicron particle size consisting of inorganic salts or oxides.
  • ceramic powders are sintered to produce components of fuel cells, wear and heat resistant elements for various devices, or to produce supercon ⁇ ducting ceramics or other electronic components.
  • the powders must have spherical shape, high density and a combination of submicron size and low specific surface.
  • the powder is of high purity, is of submicron particle size and has a suf- ficiently narrow size distribution. DESCRIPTION OF PRIOR ART.
  • aqueous homogeneous metal salt solution e.g. an aqueous homogeneous metal salt solution, or a melt is atomized into fine droplets to form an aerosol, and the droplets are treated to form powder particles which possibly are converted, e.g. by heating, possibly in the presence of reactive gases, such as oxygen or hy ⁇ drogen, to obtain the desired chemical and physical transformations before the powder is collected in a dust collector.
  • reactive gases such as oxygen or hy ⁇ drogen
  • the process of the present invention is of this last mentioned type.
  • a special embodiment of this type of process is termed spray pyrolysis, because the drop ⁇ lets are subjected to a high temperature treatment.
  • the invention deals with a process for the production of a powder of fine particles of de- sired components by producing an aerosol of droplets from a solution or melt which by drying, congealing, thermal decomposition and/or interaction and/or react ⁇ ion with gaseous compounds, especially oxygen or hydro- gen, are capable of forming said desired components, and converting the aerosol forming droplets into a powder of said desired components, and recovering said powder, comprising the steps of
  • a preferred embodiment of the present process is for the production of a ceramic powder by producing an aerosol of droplets from a solution of salts which by interaction, reaction wich gaseous compounds, and/or by thermal decomposition are capable of forming a mixture of components desired in the ceramic powder, and sub ⁇ jecting the aerosol to a heat treatment to dry the droplets and convert the solids thereof into a powder of said components, and recovering said powder, com ⁇ prising
  • an aerosol having droplets of a median volume diameter between 1.5 and 2.5 microns which droplets are present in the aerosol in a concen ⁇ tration corresponding to more than 50 g liquid per kg gas.
  • nozzles are used de ⁇ livering a very broad spray, which means that the nozzles should have a very wide spray angle.
  • the nozzle or nozzles are preferably arranged in an upward or downward position and thus delivers a spray having small angles to the horizontal plane.
  • the nozzle operates in an atomizing chamber from where the aerosol produced is carried out solely by the gas provided through the two-fluid nozzle in the atomization process.
  • This is in contrast to several prior art processes where the aerosol is carried away from the nozzle area immediate- ly after formation, by means of a high velocity gas stream.
  • the aerosol resides in the atomizing chamber changes take place as to the median volume diameter and the volume of suspended droplets as well as in the size distribution thereof. This is due to the fact that the microdroplets to a certain extent collide with the chamber walls and with each other and the largest fraction of the particles falls to the chamber bottom by gravity.
  • the above mentioned conversion zone through which the aerosol leaving the atomizing chamber is passed may typically be a high temperature area where ⁇ in the aerosol droplets are dried and converted by interactions between the components of the droplets or by reaction with gaseous components in the carrier gas, such a oxygen or hydrogen.
  • the aerosol droplets may be congealed by being passed through a cooling zone.
  • the particles thus converted may be separated from the carrier gas by means of an electrostatic precipitator or a bag filter. Due to the very fine particle size the resulting powder will usually not be free flowing and it may be most conveniently handled as a suspension or paste.
  • the invention also deals with a plant for pro ⁇ ducing a powder by the above defined processes, which plant is characterized in having an atomizing chamber which is closed except for an outlet for aerosol in the top portion thereof and an outlet for liquid in the bottom, at least one two-fluid nozzle in said chamber which when operating delivers a spray shaped as
  • a cone shell having a cone angle above 90 means for supplying pressurized gas to said at least one two-fluid nozzle, means for supplying said at least one nozzle with a solution or melt acting as precursor for the components desired in the powder, a conversion device into which said outlet for aerosol from the atomizing chamber debouches, and means for recovering the desired powder from a gas stream, said means being connected to the other end of said device.
  • a preferred embodiment of this plant has a plu ⁇ rality of two-fluid nozzles arranged in the .atomizing chamber in a horizontal arrangement, each nozzle having an exit opening pointing either upwards or downwards.
  • the top portion of the atomizing chamber is upward tapering to impart an accelerating upward movement of the aerosol leaving the chamber to enter the conversion device, e.g. a heating device.
  • the conversion device e.g. a heating device.
  • gas is used in a broad sence comprising atmospheric air, oxygen and other oxidizing gases, hydrogen and other reducing gases as well as inert gases such as nitrogen etc.
  • Fig. 1 very schematically depicts a layout for a plant suitable for performing the process of the in ⁇ vention
  • Fig. 2 shows plots referred to in an Example be ⁇ low and showing the aerosol concentration as a function of airflow for different nozzles
  • Fig. 3 is an electron micrograph of particles of maltodextrin produced by the process according to the invention.
  • Fig. 4 is an electron micrograph of particles of nickel ferrite produced by the process according to the inventio .
  • Fig. 5 referred to in an Example below shows a comparison of results using different nozzles, and
  • Fig. 6 illustrates the importance of residence time for aerosol in the atomizing chamber.
  • a spray chamber is generally de ⁇ signated l.
  • the walls thereof are cylindrical and the top portion are taper- ing towards an outlet opening 2.
  • the bottom part slants towards an exit for liquid 3.
  • a nozzle 4 is shown in the chamber 1 .
  • a battery of nozzles arranged horizontally in the chamber.
  • the nozzle 4 is shown as the preferred embodi ⁇ ment which has a resonance body 5 fixed in front of the nozzle opening.
  • This resonance body 5 may typi- cally be in the shape of a cup creating resonance waves which provides the desired cone shell shape of the cloud of droplets produced by the nozzle.
  • the nozzle 4 is supplied with atomizing gas, such as cleaned air or a reactive or inert pressurized gas, as explained above, through conduit 6.
  • atomizing gas such as cleaned air or a reactive or inert pressurized gas, as explained above
  • the liquid is supplied to the nozzle for producing the desired microdroplets.
  • the liquid may be a solution of precursor compounds for the desired powder, e.g. a ceramic powder, or it may be a melt which by ato ization and following congealing pro ⁇ cutes a desired powder.
  • the nozzle 4 produces a mist of the liquid from the source 7, which mist fills up the chamber 1.
  • the liquid which collects in the bottom of the chamber 1 is recovered through exit 3 and preferably recycl ⁇ ed to the source 7 as shown.
  • a ceramic powder In case a ceramic powder is to be produced an aerosol of a solution of precursors for the ceramic powder will be carried up into a heating device 8.
  • This device 8 may typically be a tubular fur ⁇ nace having a height ten or more times the diameter.
  • the aerosol, including the carrier gas is heated and thereby expanded which secures an accelerated movement of the droplets/ particles through the device.
  • the device 8 may have means (not shown) for introducing heating or cooling gas or reactive gases into the aerosol.
  • the atomizing gas introduced through 6, which gas subsequently acts as carrier gas in device 8 may be of a reducing character, or such a gas may be intro ⁇ pokerd separately in the device 8 to convert metal compounds into the free metals during passage through the device 8.
  • the fine particles leave the device 8 through the top portion thereof and are by means of a carrier gas introduced through conduit 9 transported into a particle collector 10, which may be an electrostatic precipitator.
  • the desired powder is recovered through 11, e.g. by washing, whereas the gas leaves through a conduit 12 and may be released to the atmosphere possibly after suitable purification or the gas may be partially recycled to 9.
  • a In the system for drying only the feed solution consisted of maltodextrin (5-40 percent by weight) in water, and B In the system for sintering an aqueous solution of ferric nitrate and nickel nitrate in a mole ratio of Fe/Ni 2:1 was used.
  • Example 1 The aerosol concentration was measured with a Leon Siegler Opacimeter calibrated by weighing the electrostatic precipitator before and after the test.
  • Example 1 The aerosol concentration was measured with a Leon Siegler Opacimeter calibrated by weighing the electrostatic precipitator before and after the test.
  • the Sonicore nozzle was equipped with a resonance cup and the MM nozzle was an externally mixing swirl two-fluid nozzle having an opening of 0.45 mm.
  • the nozzles were mounted in a NIRO spray dryer type Mobile Minor.
  • the powder was collected in a cyclone followed by a two- stage electrostatic precipitator.
  • the products from the two collectors were mixed and analysed.
  • the test results are presented in Table 1 below as test la and lb.
  • the same nozzles were mounted in a chamber having a volume of 15 liters. The outlet was 10 cm in dia ⁇ meter and connected to a 30 cm in diameter duct where hot air was introduced.
  • the product was collected in a two-stage electrostatic precipitator.
  • the test results are presented below as test 2a and 2b.
  • Span is a measure of the size distribution and is defined as (D9o _D ⁇ o) /D 50
  • the two nozzles produce comparable product charact- eristics when used without atomizing chamber.
  • the nozzle with resonance cup produces a much more con ⁇ centrated aerosol than the nozzle without resonance cup.
  • Nozzle 1 Sonicore nozzle no. 52. (With resonance cup)
  • Nozzle 2 Sonicore nozzle no. 47. (With resonance cup)
  • Nozzle 3 MM. (Without resonance cup).
  • the nozzles were operated with different gas flows. All nozzles produce a spray with a significant fraction of droplets below 4 microns under these con- ditions when selecting a proper liquid flow rate to the nozzles.
  • the velocity of the air leaving the nozzles were measured in a sphere at a distance of 50 mm from the nozzle exit.
  • the nozzles were operated without feed under these tests which was necessary to make the measurements.
  • the results are given in fig. 5 as maxi ⁇ mum gas velocity measured 50 mm from nozzle in a circle in 1st quadrant. The unit is m/s.
  • curve 1 refers to nozzle 1 at air flow 6.4 kg/h
  • curve 2 refers also to nozzle l but at air flow 7.5 kg/h
  • Curve 3 refers to nozzle 2 at an air flow of 7.5
  • curve 4 also refers to nozzle 2 but at an air flow of 11.5 kg/h
  • Curve 5 refers to nozzle 3 at an air flow of 7.5 kg/h. It can be seen from the figure 5 that the posi ⁇ tion and size of the maximum values differ from nozzle to nozzle and from operation to operation.
  • the second experiment was to measure concentra ⁇ tion and size of the aerosol leaving the spray chamber with different nozzles in operation under different but comparable conditions. The liquid feed rate was in each case adjusted to give the maximum reading of the gasphase concentration of calcined and sintered aero ⁇ sol. The results are reported below in Table 2.
  • Aerosol concentration and properties as a function of as load to s ecific nozzles Aerosol concentration and properties as a function of as load to s ecific nozzles.
  • the effect of volume of the spray chamber on aerosol MVD, SD (size distribution) and concentration at the chamber exit is illustrated in this Example, covering short retention times.
  • the test material was maltodextrine solutions. The tests were carried out with three chambers of a shape as shown in fig. 1, but with different volumes, leading to 0.3 sec, 1.2 sec. and 4.2 sec. residence time of the gas in the chamber. The gas flow was 6.4 kg/h.
  • Curves A, B and C respectively represent results for retention times of 4.2 sec, 1.2 sec and 0.3 sec. , resp.
  • the curves D and E show the difference between A and B, and A and C respectively; they represent the lost aerosol as function of retention time. It is seen in this experiment that large as well as small droplets disapear, leaving aerosols of suit ⁇ able median volume diameter, size distribution and con ⁇ centration.
  • a pilot plant as the one shown in Fig. 1 was used for preparing a ceramic powder of nickel ferrite (NiFe 2 0 3 ).
  • the volume of the atomizing chamber 1 was 15 liter and the height of the heating device 9 was 2 m and the inner diameter 20 cm.
  • the nozzle 4 was of the type termed Sonicore 52. It had a cup-shaped member 5 fixed 4 mm from the body of the nozzle, providing a wide spray angle (above 90°) .
  • This solution was at ambient temperature atomized in an amount of 1755 ml/h.
  • the heating device was adjusted to obtain a wall temperature of 900 C.
  • the density after being mixed with 4% by weight wax and subjected to a pressure of 150 bar was 3.40g/cm 3 .

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Oxygen, Ozone, And Oxides In General (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)

Abstract

On produit une poudre fine à répartition granulométrique étroite en formant un aérosol par l'atomisation de deux fluides à l'aide d'une seule buse (4) dans une chambre (2), en maintenant l'aérosol dans ladite chambre afin d'évacuer de 50 à 95 % en volume des gouttelettes de l'aérosol, et en faisant passer l'aérosol restant de la chambre d'atomisation à une zone (8) de conversion. L'installation de production de la poudre possède une chambre d'atomisation hermétique possédant au moins une buse à deux fluides formant un brouillard en forme de cône dont le sommet présente un angle supérieur à 90°. L'installation possède également un dispositif de conversion dans lequel débouche le conduit d'évacuation d'aérosol de la chambre d'atomisation.
PCT/DK1993/000001 1992-01-15 1993-01-05 Procede de production d'une poudre constituee de particules fines et installation pour sa mise en ×uvre WO1993014023A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DK4892A DK4892A (da) 1992-01-15 1992-01-15 Fremgangsmaade til fremstilling af et pulver af fine partikler samt et anlaeg til udoevelse af fremgangsmaaden
DK48/92 1992-01-15

Publications (1)

Publication Number Publication Date
WO1993014023A1 true WO1993014023A1 (fr) 1993-07-22

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AU (1) AU3448493A (fr)
DK (1) DK4892A (fr)
WO (1) WO1993014023A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2831466A1 (fr) * 2001-10-30 2003-05-02 Dgtec Dispositif de fabrication de poudre par pyrolyse d'aerosol
US6613300B2 (en) 1996-12-05 2003-09-02 Degussa Ag Doped, pyrogenically prepared oxides
CN106606887A (zh) * 2015-10-22 2017-05-03 中国石油化工股份有限公司 一种将浆料进行喷雾干燥的方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0277245A1 (fr) * 1986-07-26 1988-08-10 Chemirite, Ltd. Procede pour produire un oxyde complexe servant a produire de la ferrite
EP0285339A1 (fr) * 1987-04-01 1988-10-05 Corning Glass Works Particules d'oxyde et de sulfure métallique et leur procédé de production
WO1990015020A2 (fr) * 1989-06-09 1990-12-13 Worcester Polytechnic Institute Procede de decomposition en aerosol a temperature elevee et produits obtenus

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0277245A1 (fr) * 1986-07-26 1988-08-10 Chemirite, Ltd. Procede pour produire un oxyde complexe servant a produire de la ferrite
EP0285339A1 (fr) * 1987-04-01 1988-10-05 Corning Glass Works Particules d'oxyde et de sulfure métallique et leur procédé de production
WO1990015020A2 (fr) * 1989-06-09 1990-12-13 Worcester Polytechnic Institute Procede de decomposition en aerosol a temperature elevee et produits obtenus

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
AMERICAN CERAMIC SOCIETY BULLETIN vol. 56, no. 11, 1977, COLUMBUS (US) pages 1023 - 1024 D.M.ROY ET AL. 'PREPARATION OF FINE OXIDE POWDERS BY EVAPORATIVE DECOMPOSITION OF SOLUTIONS' *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6613300B2 (en) 1996-12-05 2003-09-02 Degussa Ag Doped, pyrogenically prepared oxides
FR2831466A1 (fr) * 2001-10-30 2003-05-02 Dgtec Dispositif de fabrication de poudre par pyrolyse d'aerosol
WO2003037498A3 (fr) * 2001-10-30 2003-10-09 Dgtec Dispositif de fabrication de poudre par pyrolyse d'aerosol
CN106606887A (zh) * 2015-10-22 2017-05-03 中国石油化工股份有限公司 一种将浆料进行喷雾干燥的方法

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DK4892D0 (da) 1992-01-15
DK4892A (da) 1993-07-16
AU3448493A (en) 1993-08-03

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