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EP1664734A1 - Procede de controle en continu de la granulometrie de poudres utilisees dans l'industrie ceramique et usine pour sa mise en oeuvre - Google Patents

Procede de controle en continu de la granulometrie de poudres utilisees dans l'industrie ceramique et usine pour sa mise en oeuvre

Info

Publication number
EP1664734A1
EP1664734A1 EP04764963A EP04764963A EP1664734A1 EP 1664734 A1 EP1664734 A1 EP 1664734A1 EP 04764963 A EP04764963 A EP 04764963A EP 04764963 A EP04764963 A EP 04764963A EP 1664734 A1 EP1664734 A1 EP 1664734A1
Authority
EP
European Patent Office
Prior art keywords
particle size
size distribution
plant
powders
powder
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.)
Withdrawn
Application number
EP04764963A
Other languages
German (de)
English (en)
Inventor
Francesco Fontana
Davide Foschi
Pietro Rivola
Silvano Valli
Bruno Zauli
Enrico Primo Tomasini
Gian Marco Revel
Nicola Paone
Fabio Ragazzini
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.)
Sacmi Imola SC
Original Assignee
Sacmi Imola SC
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
Priority claimed from IT000081A external-priority patent/ITRE20030081A1/it
Priority claimed from ITRE20040069 external-priority patent/ITRE20040069A1/it
Application filed by Sacmi Imola SC filed Critical Sacmi Imola SC
Publication of EP1664734A1 publication Critical patent/EP1664734A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
    • G01N15/02—Investigating particle size or size distribution
    • G01N15/0205—Investigating particle size or size distribution by optical means
    • G01N15/0227—Investigating particle size or size distribution by optical means using imaging; using holography
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
    • G01N2015/0096—Investigating consistence of powders, dustability, dustiness

Definitions

  • the present invention relates to a plant and relative method for controlling and determining the particle size distribution of powders used in the ceramics industry, particularly of ceramic powders obtained by spray drying or atomisation, also known as atomized powders, or powders obtained by dry grinding.
  • the plant which produces such atomized powders is commonly known as an atomizer.
  • a rapidly executed method of good accuracy and low cost is that based on processing the images obtained by suitable video cameras or photo cameras or by known optometric means; this method is known as CAIA
  • the known methods enable the particle size distribution (in weight or volume) of ceramic powders to be analysed by comparison with the required distribution. Such analysis is made in order to avoid using ceramic powders with a particle size distribution outside the specified ranges, which would give rise to the formation of tiles with such porosity as not to satisfy the conformity criteria defined in quality procedures. It of common use in practice for a technical expert to analyze the particle size distribution values of said powders and to directly adjust the parameters which regulate the operation of the powder production plant, for example the atomizer, to maintain the particle size distribution curve within a predetermined range. Such adjustments hence require the presence of an expert able to effect said measurements, process the data and then suitably vary the values of said parameters.
  • the object of the present invention is to overcome the aforesaid drawbacks within the framework of a simple and rational solution.
  • the invention proposes to automate the measurement and recording of the particle size distribution curve and to effect its control by functional connection to a system which determines the dimensional distribution of the granules leaving the powder production plant, in particular from the atomizer, by means which regulate at least one operating parameter of the plant.
  • the invention is applicable to any type of powder used in ceramics, also including for example powders obtained by dry grinding. Specific reference will be made hereinafter to powders obtained by atomization, but the description can also refer to powders obtained by other systems, by changing the regulated parameter.
  • the parameter for regulating the particle size distribution is the grinding time and, in continuous processes, the rotational speed of the mill. In atomization plants it has been found in practice that the particle size distribution curve can be conveniently regulated by choosing as parameter the slip feed pressure into the atomizer, in the sense that higher pressure produces smaller powder granules.
  • the invention comprises a control method with feed-back, defined as online, consisting of: withdrawing at least one powder sample at predetermined intervals; determining and measuring the particle size distribution of the withdrawn sample; comparing said measured particle size distribution with a reference particle size distribution by means of a processor; and regulating at least one parameter of the powder manufacturing plant influencing the particle size distribution, on the basis of the differences between the measured curve and the reference curve.
  • the parameter regulated is the slip feed pressure into the atomizer, as stated.
  • the parameter is the mill rotational speed.
  • the invention also comprises a plant for implementing the method, in accordance with claim 13.
  • Claims 14 to 23 define advantageous embodiments of said plant.
  • the plant according to the invention comprises at least one withdrawal means for withdrawing powders leaving the powder forming plant; means for calculating the particle size distribution of said powders; and a processor arranged to compare said calculated particle size distribution with a reference particle size distribution, and able to regulate at least one operating parameter of the powder production plant, which parameter is able to significantly affect the granule dimension of the powder manufactured by the plant.
  • the illustrated example relates to an atomization plant, but is also suitable for clarifying the invention in relation to other powder manufacturing systems, such as dry grinding.
  • Figure 1 is a schematic side view of a first embodiment of the plant according to the invention and of the powder forming system;
  • Figure 2 is a perspective view of the plant of Figure 1 ;
  • Figure 3 is a view of Figure 2 from above;
  • Figure 4 is a front view of Figure 2;
  • Figure 5 shows the section V-V of Figure 3
  • Figure 6 is an enlarged view of a detail of Figure 5;
  • Figure 7 is an enlarged view of a different detail of Figure 5;
  • Figure 8 is a schematic side view of a second embodiment of the plant according to the invention and of the powder forming system;
  • Figure 9 is a view in the direction of the arrow A of Figure 8.
  • Figure 10 is a view in the direction of the arrow B of Figure 8.
  • Figure 11 is a view of Figure 8 from above.
  • Said figures show the plant 1 for continuously controlling the particle size distribution of powders 2 produced by a suitable system 3.
  • the system 3 essentially comprises a known atomizer 30 into which the slip to be processed is injected by nozzles connected to a feed pump 32.
  • the pressure at which the slip is delivered by the feed pump 32 is operated and controlled, via suitable regulator means, by a processor 33 on the basis of particle size distribution values for the powders 2 measured by the plant 1 at the exit of the atomizer 30.
  • the atomizer 30 discharges the powders 2 onto a first conveyor belt 34 which then deposits the powders 2 onto an underlying second belt 35 arranged to convey them to a storage area, not shown.
  • the plant 1 for controlling the powder particle size distribution comprises a frame 4 which upperly supports withdrawal means 5 for withdrawing powders 2 leaving the atomizer 30.
  • Said withdrawal means 5 comprises a cylinder-piston unit 50, the rod of which carries a cup-shaped body 51 for collecting the powder samples to be analysed.
  • the cylinder 50 is provided at its rear with a pneumatic motor 52 the purpose of which is to rotate said body 51 through 180° to position it between a loading and discharge position respectively.
  • the cylinder-piston unit 50 translates said cup- shaped body between at least one advanced position for withdrawing the powders 2 and a retracted position for discharging the powders 2.
  • the body 51 withdraws a powder sample while the powders fall from the belt 34 to the underlying belt 35.
  • the cup-shaped body has its mouth facing downwards, and only when it lies below the powder cascade does the pneumatic motor 52 rotate the body 51 so that its mouth faces upwards.
  • the body 51 when in its retracted position the body 51 lies above a conduit 6, which in a first embodiment of the present invention is vertical and arranged to convey the powders 2 into an underlying distributor device 7.
  • the pneumatic motor 52 rotates it through 180° to discharge the powder sample contained therein into the conduit 6.
  • a scraper 53 is used positioned in front of the vertical conduit 6, its purpose being to scrape the upper edge of the body 51 to remove excess powder.
  • the conduit 6 also supports two devices 54 for blowing compressed air, their purpose being to direct the air stream into the body 51 while it translates towards its loading position.
  • the use of the two blower devices 54 enables any powder residues remaining in the body after discharge of the withdrawn powder sample to be completely removed.
  • the distributor device 7 consists of a rotary valve 70 driven by a pneumatic motor 71 ( Figure 2). Above the valve a hopper 72 is present to receive the entire powder sample withdrawn by the cup-shaped body 51.
  • the valve 70 comprises a rotating cylindrical body 73 provided with a flattened part 74 and a cavity 75, which is dimensioned to receive only a portion of said powder sample.
  • the distributor 7 is associated with a cylinder-piston unit 76 ( Figure 3) arranged to cause it to translate between an advanced loading position in which it lies below the conduit 6, and a retracted position ( Figure 7) in which it feeds said powders to means for measuring their particle size distribution.
  • the distributor 7 when in its retracted position the distributor 7 lies above an acquisition plate 8 on which it deposits the powder portion received in the cavity 75.
  • the acquisition plate 8 is supported by the frame 4 via four elastic springs 80, each of which is fixed to the top of a support rod 81 branching from the frame 4.
  • a usual vibrator device 82 is associated with the lower surface of the acquisition plate 8 to vibrate the plate 8 in order to uniformly distribute over its surface the powders discharged by the distributor.
  • the frame 4 supports an optical system 9 comprising optoelectronic means, in the example a digital photo camera 10, for acquiring digital images of the samples of powder 2 deposited onto the acquisition plate 8.
  • a lighting system which in the described example comprises a circular neon lamp, is associated with said photo camera 10 to illuminate the powders on the acquisition plate 8 in such a manner as to prevent the formation of shadows which could prejudice the quality of the images received.
  • a suction system 12 comprising a suction fan, not shown, connected by a conduit 16 ( Figure 2) to a movable spout 13 ( Figure 7) arranged to translate above the acquisition plate 8 to remove powders after the photo camera 10 has taken their image.
  • the spout 13 is operated by a cylinder-piston unit 120 supported by the frame 4 of the plant.
  • the conduit 16 is provided with a movable shutter 160 to interrupt the suction action by the suction fan.
  • the spout 13 carries a blower device 14, the purpose of which is to blow compressed air to clean the acquisition plate 8 after passage of the spout 13 in order to be certain that powder granules 2 do not remain on the plate.
  • the plant 1 is controlled by the processor 33 in accordance with the following operating procedure. It should firstly be noted that as the powders 2 deposited by the atomizer 30 onto the belt 34 tend to stratify, the samples are preferably withdrawn from at least two different points of the powder cascade by suitably regulating the advancement of the cup-shaped body 51.
  • the body 51 when in its retracted position the body 51 lies above a flexible conduit 6' ( Figure 8) arranged to convey the powders 2 directly onto the acquisition plate 8, without the aid of the distributor 7 present in the first embodiment.
  • the plate 8 is supported by a structure 60 which can be orientated; said structure 60 is hinged by suitable connections to a bracket beam 62 rigidly fixed to the frame 4 of the plant 1 by known fixing means. The fixing of the bracket beam 62 to the frame 4 by said fixing means enables the acquisition plate 8 to be positioned at a predetermined height from the ground.
  • the acquisition plate 8 can be orientated by suitable regulator means 63, positioned between the structure 60 and the beam 62, such as to enable said plate 8 to be disposed substantially horizontal. At that side opposite the side at which the conduit 6' is positioned, said plate 8 terminates with an inclined plate piece 64 which engages the mouth of a suction system 12' of known type.
  • the suction system 12' is connected to the inclined plate piece 64 by a flexible tube 16' which terminates with a shutter 160' able to open and close communication between the suction system 12' and the tube 16'.
  • the operations described hereinafter are repeated for each withdrawal point. Initially the body 51 withdraws the powder sample and overturns it into the conduit 6, 6' which transfers it into the distributor 7 and from there onto the acquisition plate 8 in the first embodiment, or transfers it directly onto the acquisition plate 8 in the second embodiment.
  • the distributor 7 is caused by the processor 33 to position itself above the acquisition plate 8. Once in position the rotary valve 70 deposits onto said acquisition plate 8 only a portion of the powders of the withdrawn sample.
  • the processor 33 causes the distributor to move into its advanced position distant from the plate 8, while at the same time the vibrator device 82 vibrates the plate 8 to distribute the powders 2 uniformly thereover.
  • the action of the vibrator device is then interrupted and the photo camera 10 takes a photograph of the powders 2 which it makes available to the processor 33.
  • the suction fan draws the powders through the movable spout 13.
  • the distributor 7 is repositioned over the acquisition plate 8 to discharge a subsequent portion of powders from the same sample. At this point the cycle is repeated a predefined number of times, until the entire powder sample withdrawn by the body 51 has been analysed.
  • the processor calculates the arithmetic mean of the particle size distribution values obtained. The aforedescribed operations are repeated for a determined number of samples withdrawn from said different withdrawal points. The processor then calculates the arithmetic mean of the average values obtained for each sample and compares it with a reference value. Based on the result of the comparison, the processor 33 varies the pressure of the slip feed pump 32.
  • the distributor 7 is absent, as are therefore the steps involved therewith, the rest of the operating cycle proceeding as heretofore described.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Disintegrating Or Milling (AREA)

Abstract

L'invention concerne un procédé de contrôle en continu de la granulométrie de poudres céramiques sortant de l'usine de formation de poudres, comprenant au moins les étapes consistant : à retirer au moins un échantillon de poudre à intervalles prédéterminés ; à mesurer la granulométrie de l'échantillon retiré ; à comparer la granulométrie mesurée avec une granulométrie de référence à l'aide d'une machine de traitement ; à régler au moins un paramètre de ladite usine de formation de poudres influençant la granulométrie, en fonction des différences entre la granulométrie mesurée et la granulométrie de référence ; ainsi qu'une usine pour sa mise en oeuvre.
EP04764963A 2003-09-12 2004-09-07 Procede de controle en continu de la granulometrie de poudres utilisees dans l'industrie ceramique et usine pour sa mise en oeuvre Withdrawn EP1664734A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
IT000081A ITRE20030081A1 (it) 2003-09-12 2003-09-12 Impianto e metodo di controllo continuo della
ITRE20040069 ITRE20040069A1 (it) 2004-06-11 2004-06-11 Metodo per il controllo continuo della granulometria di polveri impiegate nella industria ceramica, ed impianto di attuazione
PCT/EP2004/010022 WO2005026699A1 (fr) 2003-09-12 2004-09-07 Procede de controle en continu de la granulometrie de poudres utilisees dans l'industrie ceramique et usine pour sa mise en oeuvre

Publications (1)

Publication Number Publication Date
EP1664734A1 true EP1664734A1 (fr) 2006-06-07

Family

ID=34315479

Family Applications (1)

Application Number Title Priority Date Filing Date
EP04764963A Withdrawn EP1664734A1 (fr) 2003-09-12 2004-09-07 Procede de controle en continu de la granulometrie de poudres utilisees dans l'industrie ceramique et usine pour sa mise en oeuvre

Country Status (2)

Country Link
EP (1) EP1664734A1 (fr)
WO (1) WO2005026699A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ITRE20060112A1 (it) * 2006-09-27 2008-03-28 Sacmi Cooperativa Meccanici Imola Soc Coop Impianto per il controllo della granulometria di polveri, e metodo
ES2934880B2 (es) * 2021-08-27 2023-07-03 Asociacion De Investig De Las Industrias Ceramicas A I C E Sistema y metodo de medida automatica en continuo del tamano de particulas de suspensiones concentradas mediante imagineria de rayos x

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2855583C2 (de) * 1977-12-29 1984-07-12 Sumitomo Metal Industries, Ltd., Osaka Verfahren zur Bestimmung der Korngrößenverteilung von Korngemischen
NO163384C (no) * 1987-12-18 1990-05-16 Norsk Hydro As Fremgangsmaate ved automatisk partikkelanalyse og anordning for dens utfoerelse.
US5426501A (en) * 1993-01-06 1995-06-20 Laser Sensor Technology, Inc. Apparatus and method for particle analysis
US5522555A (en) * 1994-03-01 1996-06-04 Amherst Process Instruments, Inc. Dry powder dispersion system
JP3398121B2 (ja) * 2000-05-16 2003-04-21 株式会社堀場製作所 粒度分布測定装置
US6600559B2 (en) * 2001-03-22 2003-07-29 Eastman Kodak Company On-line method for detecting particle size during a milling process
US6683975B2 (en) * 2001-06-18 2004-01-27 Abbott Laboratories Apparatus and method for determining the dispersibility of a product in particulate form
DE20304637U1 (de) * 2003-03-22 2003-10-02 Institut für Qualitätssicherung von Stoffsystemen Freiberg e.V., 09599 Freiberg Bildanalysesystem zur Charakterisierung der Homogenität feinster Partikelsysteme

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2005026699A1 *

Also Published As

Publication number Publication date
WO2005026699A1 (fr) 2005-03-24

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