US3726484A - Stepped fluid energy mill - Google Patents

Stepped fluid energy mill Download PDF

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Publication number
US3726484A
US3726484A US00189586A US3726484DA US3726484A US 3726484 A US3726484 A US 3726484A US 00189586 A US00189586 A US 00189586A US 3726484D A US3726484D A US 3726484DA US 3726484 A US3726484 A US 3726484A
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Prior art keywords
chamber
discontinuities
mill
percent
fluid
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G Schurr
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EIDP Inc
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EI Du Pont de Nemours and Co
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C19/00—Other disintegrating devices or methods
    • B02C19/06—Jet mills
    • B02C19/061—Jet mills of the cylindrical type

Definitions

  • Most fluid energy mills are variations on a basic configuration of a disc-shaped chamber enclosed by two generally parallel circular plates defining axial walls and an annular rim defining a peripheral wall, the axial length or height of the chamber being substantially less than the diameter.
  • a number of uniformly spaced jets for injecting the gaseous fluid which furnishes the energy for comminution, along with one or more injectors for feeding the particulate solids to be comminuted.
  • the jets are oriented such that the gaseous fluid and particulate solids are injected tangentially to the circumference of a circle smaller than the chamber circumference.
  • a conduit coaxial to and in direct communication with the grinding chamber is provided for discharge of the comminuted solids to a cyclone or bag filter for collection.
  • Fluid energy mills combine both grinding and classification within a single chamber, and the fluid mechanical principles governing these two processes have been described in the literature.
  • a vortex is created wherebythe particles are swept along a spiral path to be eventually discharged at the central outlet.
  • the passage of the fluid conveying the particles can be resolved into a tangential component of velocity, V which is a measure of the centrifugal force acting on the particle tending to.
  • V radial component of velocity
  • Fluid energy mills are best adapted to comminution of accretions or aggregates of single particles. Although they are generally recognized to be unexcelled for this purpose, nevertheless it has been observed that considerably more material of undesirably large particle sizes frequently escapes into the product than would be expected on the basis of the calculated cut size for the particular conditions prevailing during milling. To reduce the amount of oversized material, it has been necessary to increase the intensity of grinding by reducing the solids feed rate and increasing the fluid to solids ratio with consequent greater costs in terms of reduced capacity per mill. In many cases in the titanium dioxide pigments industry this also results in what is termed over grinding of the pigment with adverse effects being noted in color and chalking resistance. Although various modifications heretofore have been proposed aimed at preventing passage of this unwanted, oversized material into the product, none has proven to be wholly satisfactory.
  • this deficiency of vortex-type fluid energy mills is alleviated by providing discontinuities in'the axial walls. More specifically, I have found that by providing paraxially symmetric discontinuities projecting from the axial walls of the chamber, there is a reduction in the radial velocity near those walls such that substantially improved classification and grinding functions are achieved.
  • discontinuity is used herein in its accepted fluid flow sense to define intersecting surfaces, i.e. as opposed to curved surfaces, over which a gas cannot flow without creating at least some small boundary zone of reduced pressure.
  • the discontinuities in the axial walls of the fluid energy mill of the invention will be abruptly divergent, i.e. stepshaped-in cross-section as would be defined by surfaces intersecting at less than
  • the discontinuities, which are concentric of the chamber axis, should be located at a distance of 0.86-0.50 Rtherefrom, most preferably'at about 0.70 to 0.80 R, where R is the radius of the chamber as measured from the cylindrical axis of the chamber to the periphery.
  • each of the projections from the axial walls has been found to be of little im portance but in general it is preferred that together they effect a change in chamber height by about 5 to 50 percent.
  • a projection of at least is inch from each axial wall (1/8 inch total) is desired, but a preferred minimum is 0.10 inch to give a total chang in paraxial height of at least 0.20 inch.
  • the invention makes it possible to achieve a superior product with respect to smallerparticles and narrower size distributions than prior art methods.
  • a further advantage of the invention is that the improved comminution can be accomplished without unnecessarily restricting fluid flow and thus without reducing grinding rates or causing pluggage.
  • FIG. 1 shows in vertical cross-section an apparatus of the invention
  • FIG. 2 is a horizontal cross-section of the device of FIG. 1 taken normal to the axis at the level of the inlet jets,
  • FIGS. 3, 4, 5, 6 and 7 illustrate in cross-sectional elevational views, vortex chambers having discontinuities of various shapes.
  • FIG. 1 and FIG. 2 1 is a source of fluid, which in the case of superheated steam has temperatureand pressure-controlling capabilities.
  • Afluid header 2 encircles the peripheral wall 4 of circular grinding chamber 5.
  • the wall of the cylindrical discharge port 6 and the exhaust duct 7 are axially located.
  • Each nozzle, 3, enters the peripheral wall 4 of the chamber at an angle such that the extension of the nozzle axis is tan-' gent to a circle about the center of the chamber which has a radius smaller than the radius, R, of the chamber;
  • a multiplicity of these nozzles is advantageously used, l6being convenient for a chamber of 36 inches diameter.
  • the chamber is shown to be relatively disc shaped, its actual dimensions being determined by the upper and lower circular plates 8 and 9, peripheral wall or rim 4, and the pair of identical upper and lower rings ll defining opposing, concentric, symmetrical discontinuities 12.
  • a venturi feeding device 10 serves to introduce the solid material to be ground to the chamber, it being aligned somewhat tangentially to facilitate flow of the solids and fluid into the chamber vortex.
  • the chamber should be provided with suitably shaped liners of hardened alloy or refractory carbides.
  • the discontinuities, or steps are located at a distance of between 0.86 and 0.50 Rfrom the vortical or chamber axis where R is, as depicted in FIG. 3, the radius of the chamber measured from the central axis of the periphery.
  • R is, as depicted in FIG. 3, the radius of the chamber measured from the central axis of the periphery.
  • the optimum location of the steps will depend somewhat on the geometry of the grinding chamber, the size of the discharge outlet and the rates atwhich fluid and solids are to be charged.
  • each axial wall may be advantageous, as illustrated in FIG. 5.
  • the vortex chamber shown in FIG. 3 will be seen to have a paraxial height, h, two discontinuitieslZ which are triangular in cross-section and each of a height, y.
  • the discontinuities are separated by a distance, x, which is equal to 2y and which should be about 5 to 50 percent of h.
  • the angle of the discontinuity will be seen to be about
  • the discontinuities constitute 90 steps.
  • each discontinuity is formed by a pair of abrupt steps.
  • FIGS. 6 and 7 represent still other embodiments.
  • the axial walls may be relatively planar or may be converging as, for example, is described in U.S. Pat. No. 3,462,086.
  • discharge ports 6 and 7 both concentrically located around the vertical axis, enable the comminuted product to discharge in one direction to a separator, whereas, the gaseous fluid is discharged in the opposite direction.
  • product and gas may be discharged through a single large conduit, located on either wall, to cyclones or bag filters.
  • EXAMPLE I The particulate solid employed in Profax polypropylene powder manufactured by Hercules, Inc. It is composed of agglomerates of individual particles of 0.08 microns average diameter, the agglomerates having sizes, as measured by screening tests, percent by weight greater than 74 microns and percent by weight greater than 37 microns.
  • Air at 75F. and 100 p.s.i.g. is used as the source of energy for the vortex and for feeding the polypropylene powder.
  • the air feed rate is 100 SCFM.
  • the venturi type feed injector is fed by a vibrating feeder delivering solids with a i 2 percent by weight accuracy.
  • Both gas and comminuted solids are discharged from an upwardly directed central conduit of 4 inches diameter into a filter bag measuring 50 ft. in area. Particle size distributions of the comminuted products are determined by a Laboratory Jet Sieve manufactured by the Alpine Corporation.
  • the mill design corresponds generally to that described in connection with FIGS. 1, 2 and 3.
  • axial end plates are utilized to give a peripheral grinding section converging inwardly at a 14 angle for a radial distance of one inch from the periphery.
  • a A inch step is provided in each axial wall to give a total increase in paraxial height of onehalfinch, i.e., h is one inch.
  • polypropylene powder under the conditions described leads to a comminuted powder in which 99 percent by weight is less than 74 microns in size whereas 84 percent by weight is less than 34 microns in size.
  • the product contains 99.6 percent by weight less than 74 microns in size, and 95.0 percent by weight less than 37 microns in size.
  • Particle size analysis of a comminuted Control at 50 lbs/hr. solids feed shows that only 81 percent by weight of the particles are less than 74 microns in size and only 72 percent by weight are less than 37 microns in size. When the solids feed is reduced to 25 lbs/hr. still only 90 percent by weight is less than 74 microns and only 85 percent by weight is less than 37 microns.
  • the mill configuration corresponds to that shown in FIG. 4.
  • the grinding section consisting of parallel axial walls one-half inch apart, extend from the periphery inwardly for 1 inch to a point at 0.75 R where steps in each axial wall provide a total increase of one-half inch in the paraxial height of the chamber.
  • the axial walls then continue parallel to one another until intersecting with the exit port.
  • Feeding the polypropylene powder, at 50 lbs./hr. gives a product having a screen analysis of 97 percent by weight less than 74 microns in size and 72 percent by weight less than 37 microns in size. At a feed rate of 25 lbs./hr., the product is analyzed to be 99 percent by weight less than 74 microns in size and 90 percent by weight less than 37 microns in size.
  • EXAMPLE III 74 microns in size and 80 percent by weight less than 37 microns in size. At a solids feed of 25 lbs./hr., 98.4 percent by weight of the product is less than 74 microns in size and 96 percent by weight is less than 37 microns in size.
  • the conditions are the same except that the solids feed is 43 lbs/hr.
  • the ground product is found, by wet screen analysis, to contain 94.3 percent by weight less than 20 microns in size.
  • a correspondingly produced Control product has only 81.8 percent by weight less than 20 microns in size.
  • EXAMPLE V In this case the mill is of the same dimensions and configuration as that described in Example I, except that product is discharged from a 5 inch diameter conduit attached to the bottom plate and fluid escapes through a smaller conduit attached to the upper plate.
  • the powder to be comminuted is a high gloss rutile TiO pigment.
  • the fluid supplied to the seven ring jets and one feed jet is superheated steam at 128 p.s.i.g., 400C. While maintaining a constant steam flow of 320 lbs./hr., the TiO is fed to the mill at various rates ranging from 5.2 to 1.3 lbs. steam/lb. TiO (62-250 lbs. TiO per hour), taking precautions that uniform conditions prevail at each feed rate before taking samples.

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  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Disintegrating Or Milling (AREA)
  • Crushing And Grinding (AREA)
US00189586A 1971-10-15 1971-10-15 Stepped fluid energy mill Expired - Lifetime US3726484A (en)

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US18958671A 1971-10-15 1971-10-15

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US (1) US3726484A (es)
JP (1) JPS58898B2 (es)
AR (1) AR194277A1 (es)
BR (1) BR7207179D0 (es)
CA (1) CA989370A (es)
DE (1) DE2250226C3 (es)
GB (1) GB1404060A (es)

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2451222A1 (fr) * 1979-03-16 1980-10-10 Microfuels Inc Procede et dispositif de fractionnement de substances pulverulentes a l'energie fluidique
US4502641A (en) * 1981-04-29 1985-03-05 E. I. Du Pont De Nemours And Company Fluid energy mill with differential pressure means
US4979684A (en) * 1988-07-27 1990-12-25 Basf Aktiengesellschaft Dispersion, comminution or deagglomeration and classification of solids
US5135899A (en) * 1988-06-03 1992-08-04 Thomas Garoff Method for the activation of a carrier for a polymerization catalyst, and a catalyst component obtained using the method
US5154360A (en) * 1992-02-07 1992-10-13 E. I. Du Pont De Nemours And Company Process of making X-ray phosphors having improved efficiency
US5476093A (en) * 1992-02-14 1995-12-19 Huhtamaki Oy Device for more effective pulverization of a powdered inhalation medicament
US5637344A (en) * 1995-10-20 1997-06-10 Hershey Foods Corporation Chocolate flavored hard candy
WO1997032668A1 (en) * 1996-03-08 1997-09-12 E.I. Du Pont De Nemours And Company Improved fluid energy mill
WO1997033695A1 (en) * 1996-03-12 1997-09-18 Vladimir Ivanovich Razmaitov Method of turbulence-pulverisation of materials (variants) and device for carrying out said method (variants)
WO1998052694A1 (en) * 1997-05-23 1998-11-26 Super Fine Ltd. Controlled comminution of materials in a whirl chamber
WO2000056460A1 (en) * 1999-03-23 2000-09-28 Polifka Francis D Apparatus and method for circular vortex air flow material grinding
US6575160B1 (en) 1997-08-07 2003-06-10 Art Slutsky Inhalation device
WO2003070373A1 (en) * 2002-02-20 2003-08-28 Super Fine Ltd. Vortex mill for milling solids
EP1512463A1 (en) * 2003-09-05 2005-03-09 Nisshin Engineering Inc. Jet mill
US6971594B1 (en) 1999-03-23 2005-12-06 Vortex Dehydration Technology, Llc Apparatus and method for circular vortex air flow material grinding
US20070095253A1 (en) * 2005-11-01 2007-05-03 Diemer Russell B Jr Titanium dioxide finishing process
WO2007050682A2 (en) 2005-10-27 2007-05-03 E. I. Du Pont De Nemours And Company Process for producing titanium dioxide
US7246617B1 (en) 1999-06-23 2007-07-24 Vectura Delivery Devices Limited Inhalers
WO2008057354A2 (en) 2006-11-02 2008-05-15 E. I. Du Pont De Nemours And Company Process for producing titanium dioxide particles having reduced chlorides
US7398934B1 (en) 2007-05-15 2008-07-15 E.I. Du Pont De Nemours And Company Deep-chamber, stepped, fluid-energy mill
US20090211576A1 (en) * 2007-10-02 2009-08-27 Timo Lehtonen Safety and abuse deterrent improved device
CN102189031A (zh) * 2010-03-15 2011-09-21 钦州鑫能源科技有限公司 浆体颗粒破碎装置
US20120037736A1 (en) * 2004-07-09 2012-02-16 Sunrex Kogyo Co., Ltd. Jet mill
US11045815B2 (en) * 2016-01-21 2021-06-29 Sakai Chemical Industry Co., Ltd. Powder grinding method and powder grinding machine
US11235337B2 (en) * 2018-08-23 2022-02-01 NEIZSCH Trockenmahltechnik GmbH Method and device for discharging hard to grind particles from a spiral jet mill

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3201778C1 (en) * 1982-01-21 1983-10-06 Kronos Titan Gmbh Device for jet milling solids, in particular pigments, which are composed of fine particles
JPS60175599U (ja) * 1984-04-28 1985-11-20 カ−ル事務器株式会社 パンチ
US5281379A (en) * 1989-04-05 1994-01-25 Kanebo, Ltd. Processes for manufacturing thermoplastic resin compositions
JP4747130B2 (ja) * 2007-04-26 2011-08-17 株式会社日清製粉グループ本社 粉体分級装置
JP2009090255A (ja) * 2007-10-11 2009-04-30 Earth Technica:Kk 粉体処理設備
RU170192U1 (ru) * 2016-11-14 2017-04-18 федеральное государственное автономное образовательное учреждение высшего образования "Санкт-Петербургский национальный исследовательский университет информационных технологий, механики и оптики" (Университет ИТМО) Струйный диспергатор пищевых добавок

Citations (3)

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Publication number Priority date Publication date Assignee Title
US2191095A (en) * 1937-09-01 1940-02-20 Internat Pulverizing Corp Centrifugal fluid jet pulverizer
US2690880A (en) * 1951-04-10 1954-10-05 Freeport Sulphur Co Rectilinear pulverizer
US3559895A (en) * 1968-02-20 1971-02-02 Edwin F Fay Apparatus for and method of comminuting solid materials

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3178121A (en) * 1962-04-24 1965-04-13 Du Pont Process for comminuting grit in pigments and supersonic fluid energy mill therefor
US3462086A (en) * 1966-07-01 1969-08-19 Du Pont Fluid energy milling process

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2191095A (en) * 1937-09-01 1940-02-20 Internat Pulverizing Corp Centrifugal fluid jet pulverizer
US2690880A (en) * 1951-04-10 1954-10-05 Freeport Sulphur Co Rectilinear pulverizer
US3559895A (en) * 1968-02-20 1971-02-02 Edwin F Fay Apparatus for and method of comminuting solid materials

Cited By (42)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0017367A1 (en) * 1979-03-16 1980-10-15 MICROFUELS, Inc. Apparatus and method for comminution of pulverulent material by fluid energy
FR2451222A1 (fr) * 1979-03-16 1980-10-10 Microfuels Inc Procede et dispositif de fractionnement de substances pulverulentes a l'energie fluidique
US4502641A (en) * 1981-04-29 1985-03-05 E. I. Du Pont De Nemours And Company Fluid energy mill with differential pressure means
US5135899A (en) * 1988-06-03 1992-08-04 Thomas Garoff Method for the activation of a carrier for a polymerization catalyst, and a catalyst component obtained using the method
US4979684A (en) * 1988-07-27 1990-12-25 Basf Aktiengesellschaft Dispersion, comminution or deagglomeration and classification of solids
US5154360A (en) * 1992-02-07 1992-10-13 E. I. Du Pont De Nemours And Company Process of making X-ray phosphors having improved efficiency
WO1993016146A1 (en) * 1992-02-07 1993-08-19 E.I. Du Pont De Nemours And Company Process of making x-ray phosphors having improved efficiency
US5476093A (en) * 1992-02-14 1995-12-19 Huhtamaki Oy Device for more effective pulverization of a powdered inhalation medicament
US5637344A (en) * 1995-10-20 1997-06-10 Hershey Foods Corporation Chocolate flavored hard candy
US6145765A (en) * 1996-03-08 2000-11-14 E. I. Du Pont De Nemours And Company Fluid energy mill
WO1997032668A1 (en) * 1996-03-08 1997-09-12 E.I. Du Pont De Nemours And Company Improved fluid energy mill
WO1997033695A1 (en) * 1996-03-12 1997-09-18 Vladimir Ivanovich Razmaitov Method of turbulence-pulverisation of materials (variants) and device for carrying out said method (variants)
US5855326A (en) * 1997-05-23 1999-01-05 Super Fine Ltd. Process and device for controlled cominution of materials in a whirl chamber
WO1998052694A1 (en) * 1997-05-23 1998-11-26 Super Fine Ltd. Controlled comminution of materials in a whirl chamber
AU757048B2 (en) * 1997-05-23 2003-01-30 Super Fine Ltd. Controlled comminution of materials in a whirl chamber
US6575160B1 (en) 1997-08-07 2003-06-10 Art Slutsky Inhalation device
WO2000056460A1 (en) * 1999-03-23 2000-09-28 Polifka Francis D Apparatus and method for circular vortex air flow material grinding
US6971594B1 (en) 1999-03-23 2005-12-06 Vortex Dehydration Technology, Llc Apparatus and method for circular vortex air flow material grinding
US7246617B1 (en) 1999-06-23 2007-07-24 Vectura Delivery Devices Limited Inhalers
WO2003070373A1 (en) * 2002-02-20 2003-08-28 Super Fine Ltd. Vortex mill for milling solids
US6789756B2 (en) * 2002-02-20 2004-09-14 Super Fine Ltd. Vortex mill for controlled milling of particulate solids
US20050051649A1 (en) * 2003-09-05 2005-03-10 Kenji Taketomi Jet mill
EP1512463A1 (en) * 2003-09-05 2005-03-09 Nisshin Engineering Inc. Jet mill
US7258290B2 (en) 2003-09-05 2007-08-21 Nisshin Engineering Inc. Jet mill
US8398007B2 (en) * 2004-07-09 2013-03-19 Sunrex Kogyo Co., Ltd. Jet mill
US20120037736A1 (en) * 2004-07-09 2012-02-16 Sunrex Kogyo Co., Ltd. Jet mill
US20070172414A1 (en) * 2005-10-27 2007-07-26 Subramanian Narayanan S Process for producing titanium dioxide
US7476378B2 (en) 2005-10-27 2009-01-13 E.I. Dupont Denemours & Company Process for producing titanium dioxide
WO2007050682A2 (en) 2005-10-27 2007-05-03 E. I. Du Pont De Nemours And Company Process for producing titanium dioxide
US7247200B2 (en) 2005-11-01 2007-07-24 E. I. Du Pont De Nemours And Company Titanium dioxide finishing process
WO2007053584A1 (en) 2005-11-01 2007-05-10 E. I. Du Pont De Nemours And Company Titanium dioxide finishing process
US20070095253A1 (en) * 2005-11-01 2007-05-03 Diemer Russell B Jr Titanium dioxide finishing process
US8114377B2 (en) 2006-11-02 2012-02-14 E.I. Du Pont De Nemours And Company Process for producing titanium dioxide particles having reduced chlorides
US20080187486A1 (en) * 2006-11-02 2008-08-07 Alan Roger Eaton Process for producing titanium dioxide particles having reduced chlorides
WO2008057354A2 (en) 2006-11-02 2008-05-15 E. I. Du Pont De Nemours And Company Process for producing titanium dioxide particles having reduced chlorides
WO2008143926A1 (en) * 2007-05-15 2008-11-27 E.I. Du Pont De Nemours And Company Deep-chamber, stepped, fluid-energy mill
US7398934B1 (en) 2007-05-15 2008-07-15 E.I. Du Pont De Nemours And Company Deep-chamber, stepped, fluid-energy mill
US20090211576A1 (en) * 2007-10-02 2009-08-27 Timo Lehtonen Safety and abuse deterrent improved device
CN102189031A (zh) * 2010-03-15 2011-09-21 钦州鑫能源科技有限公司 浆体颗粒破碎装置
CN102189031B (zh) * 2010-03-15 2014-05-14 钦州鑫能源科技有限公司 浆体颗粒破碎装置
US11045815B2 (en) * 2016-01-21 2021-06-29 Sakai Chemical Industry Co., Ltd. Powder grinding method and powder grinding machine
US11235337B2 (en) * 2018-08-23 2022-02-01 NEIZSCH Trockenmahltechnik GmbH Method and device for discharging hard to grind particles from a spiral jet mill

Also Published As

Publication number Publication date
DE2250226C3 (de) 1981-12-17
BR7207179D0 (pt) 1973-08-30
DE2250226B2 (de) 1981-04-23
AR194277A1 (es) 1973-06-29
DE2250226A1 (de) 1973-04-19
JPS4847655A (es) 1973-07-06
GB1404060A (en) 1975-08-28
CA989370A (en) 1976-05-18
JPS58898B2 (ja) 1983-01-08

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