US3508714A - Multiple section fluid energy grinding mill - Google Patents

Multiple section fluid energy grinding mill Download PDF

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Publication number
US3508714A
US3508714A US703647A US3508714DA US3508714A US 3508714 A US3508714 A US 3508714A US 703647 A US703647 A US 703647A US 3508714D A US3508714D A US 3508714DA US 3508714 A US3508714 A US 3508714A
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Prior art keywords
mill
particles
fluid
nozzles
grinding
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US703647A
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English (en)
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Nicholas N Stephanoff
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Fluid Energy Processing and Equipment Co
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Fluid Energy Processing and Equipment 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
    • B02C19/063—Jet mills of the toroidal type

Definitions

  • the impact of the streams of particles from the two mill portions are substantially angular and may be effected in an area between the two mill portions for a more direct impact, or the streams may be projected in the same annular path for a less direct impact and a greater degree of blending to form a circulating vortex.
  • This invention relates to an apparatus for grinding or pulverizing solid material, and it particularly relates to the so-called fluid energy method of grinding wherein a high velocity elastic fluid, such as a gas or vapor, is utilized as the grinding medium in a so-called double mill.
  • a high velocity elastic fluid such as a gas or vapor
  • the ordinary fluid energy type of grinding mill comprises a curved or annular duct having a feed inlet adjacent the bottom portion for feeding the granular solid raw material into the mill and a plurality of tangentially arranged inlet nozzles at the bottom through which the elastic fluid is inserted at high velocities.
  • This bottom portion constitutes the primary grinding chamber wherein the raw solids are caught up and hurled against each other by the incoming gaseous fluids which form a vortex because of the tengency of the fluid nozzles.
  • the solid particles are pulverized by these impacts.
  • the pulverized particles because of the centrifugal force imparted thereto by the high velocity gases, together with the gaseous vortex, are impelled upwardly from the bottom grinding chamber through the so-called upstack portion of the curved or oval mill.
  • the more finely ground particles, being relatively light are entrained in the gaseous vortex and are carried by the viscous drag of the gases around the inner periphery of the mill.
  • the lighter particles are carried by the used-up gases, or those which have lost a large part of their vortex energy, through an outlet duct opening from the inner periphery of the mill to a collection station, while the heavier particles and remaining vortex gases are carried by their centrifugal force around the outer periphery back to the grinding chamber where the heavier particles are again subjected to im act by freshly fed solids.
  • the maximum mill circulating velocity obtainable is about 25% that of the velocity of the fluid as it leaves the inlet nozzle. This is due to the fact that although the velocity of the fluid and particles on the outer periphery of the vortex is increased because of their centrifugal force, the velocity on the inner periphery is so low as to measure zero or even negative velocity at times, especially when an insufficient amount of fluid enters through the nozzles so that there is not enough circulating fluid to fill the void created by the centrifugally outward shift of the fluid. The total velocity of the circulating fluid is, therefore, consideraly diminished relative to the entrance velocity. In practice, the circulation also depends, to some extent, on the frangibility of the material being processed, the weight and size of the particles, and the amount and rate of feed of the material, the heavier the load borne by the fluid, the slower the circulation.
  • the aforementioned parent application discloses a double mill assembly which overcomes the above and other problems of prior fluid energy mills and comprises a mill assembly wherein two generally annular mill portions are provided, each extending in an opposite direction from the other, but both joining at a common central upstack.
  • Solid particles were fed into each mill portion from opposite directions and fluid nozzles were provided to inject high velocity fluid, such as air, steam or the like, into the mills. These fluids propelled the opposed streams of solid particles toward each other to effect a collision between them below the central upstack. The forces generated by the collisions served to pulverize the particles, which then passed up through the central upstack.
  • the stream of pulverized particles including both the finer, lighter particles and the larger, heavier particles then separated into two streams at the upper end of the upstack, one stream passing through one mill portion and the other stream passing through the other mill portion.
  • the lighter particles were centrifugally separated and passed from the mill, while the heavier particles passed down to be entrained in new fluid jet streams, together with newly fed particles, to be propelled against each other for further collisions.
  • the above-described double mill has been found to be very effective for its purposes. However, it has been found that, in addition to impacting against each other, the high velocity streams impacted against the chamber walls of the mill and caused excessive wear thereon because of the abrasive effect of the particles. Furthermore, the resultant ground particles were, for the most part, very jagged and irregular, and although this might be immaterial for some types of product, it could not be satisfactorily used for products where the particles were required to be relatively smooth and rounded. In addition, at least some of the energy generated in the mill was not fully utilized, thereby not attaining the utmost efl'iciency.
  • Another object of the present invention is to provide a double mill which is effective to produce particles of smooth, generally rounded surfaces.
  • Another object of the present invention is to provide a double mill" wherein the energy produced is substantially fully utilized in the grinding process.
  • FIG. 1 is a sectional view of a double mill embodying the present invention.
  • FIG. 2 is a cross-sectional view taken on line 22 of FIG. 1.
  • FIG. 3 is a cross-sectional view taken on line 33 of FIG. 1.
  • FIG. 4 is a sectional view of a modified form of the mill of FIG. 1.
  • FIG. 5 is a sectional view of an alternative form of mill embodying the present invention.
  • FIGS. 1, 2 and 3 a double mill, generally designated 10, comprising a right hand mill portion 12 and a left hand mill portion 14.
  • the mill portion 12 includes a downstack 16 integral with a curved inlet chamber 18 at the bottom.
  • a feed duct 20, for feeding solid particles, leads into the top of the inlet chamber 18.
  • the inlet chamber 18 is provided with a plurality of fluid inlet nozzles 22 in fluid communication with a manifold 24.
  • the manifold 24 is supplied with fluid under pressure, such as air or steam or any other desired gas or vapor, from a header 26 having one or more inlets 28 adapted to be connected to a source of the fluid under pressure (not shown).
  • the nozzles 22 are arranged at progressively more acute angles relative to the horizontal, from right to left as shown, so that although the most left hand ones are directed to project a stream almost horizontally, they gradually direct their streams angularly upward so that the bulk of the total stream moves not only leftward but upward, the mean vector force bein g at an angle of approximately 40-45
  • the mill portion 14 is similar to mill portion 12 and also includes a downstack 30 integral with a curved inlet chamber 32 provided with a solids feed duct 34.
  • the inlet chamber 32 is also provided with a plurality of fluid nozzles 36 arranged in gradually changing angular directions similar to the nozzles 22 but in opposite direction thereto.
  • the nozzles 36 are also in communication with the manifold 24.
  • Both inlet chambers 18 and 32 merge into an upstack 38, and the fluid streams from the nozzles 22 and 36 blend (as shown in FIG. 1) to form a convergent stream passing upwardly into the upstack 38.
  • the upper end of the upstack 38 is integral with two oppositely extending, curved elbow portions 40 and 42 which form the classifier sections of the mill. These classifier sections 40 and 42 merge with the upper ends of the respective downstacks 16 and 30, and at the areas of merger are provided the respective outlets or exhaust ducts 44 and 46 leading to a common or separate collection station or stations (not shown).
  • the mill portions are not annular in cross-section but are provided with contours best adapted to their functioning.
  • the downstacks 16 and 30 have a crosssection wherein the walls taper outwardly as they progress toward the center of the mill. This is for the purpose of concentrating the heavier particles, which pass in the outer peripheral portion of the mill, to provide greater pulverizing eifects in that area.
  • the upstack 38 is, on the other hand, provided with its walls tapering inward toward the center since the upcoming stream of pulverized particles and fluid are concentrated at the center.
  • FIG. 3 shows the cross-sectional contour of the two inlet chambers 18 and 32 and the dispositions of the fluid nozzles 22 and 36 therein.
  • the solid particles are fed through inlets 20 and 34, and, as they pass into the respective inlet chambers 18 and 32, they are entrained by the high pressure, high velocity fluid from the respective nozzles 22 and 36 and projected in the paths shown in FIG. 1.
  • FIG. 1 although the opposite streams of particles impact against each other, the major portion of such impacts are angular rather than direct. In other words, there is a sort of blending. The sum vector force is therefore upwardly. This has various important results. One result is that there is very little, if any, bombardment of the chamber walls, thereby increasing their longevity. Another result is that the upward flow through the upstack is increased because of the total upward direction of the streams.
  • a third result is that because of the tangential impact of the major portion of the particles against each other, there is a sort of rolling effect between the particles which causes a smooth, rounding thereof rather than the formation of jagged edges such as would be caused by direct cross-impact.
  • the stream passes upwardly through the upstack 38, it separates at the top into two opposed streams, one passing through the classifier section 40 and the other through the classifier section 42.
  • the streams passing through these sections have the lighter, smaller particles on the inner periphery and the heavier, larger particles on the outer periphery.
  • the lighter particles pass through the respective exhaust ducts 44 and 46, while the heavier particles pass down, while in turbulence, whereby additional pulverization continues to take place, toward the respective inlet chambers 18 and 32. During this passage, they are intermixed with newly fed particles from the respective inlets 20 and 34 and are recycled therewith for another pass through the mill.
  • FIG. 4 there is shown a double mill, generally designated 100, which is, in most respects, identical to the mill shown in FIGS. 13, except that there is only one feed duct 102 leading into the right hand mill portion 104, and only one exhaust duct 106 leading from the same mill portion 104.
  • the left hand mill portion 108 has neither a feed inlet nor an exhaust duct.
  • Both inlet chambers 110 and 112, respectively, are provided with fluid nozzles 114 and 116, respectively, which are identical to those shown in FIG. 1.
  • the re sultant paths of impact are, therefore, the same.
  • the pulverizing action is primarily due to the vortex action of the impinging streams rather than direct counter-impact of the particles.
  • the bulk of the smaller, lighter particles then pass up through the upstack 118.
  • a large proportion of the larger, heavier particles while still under the initial velocity due to their direction of feed and the fluid from nozzles 114, kick over into chamber 116 and pass up through the stack 120 of the left hand mill, which, in this case, also acts as an upstack.
  • FIG. 5 illustrates another embodiment of the invention wherein the mill, generally designated 200, is almost identical to that shown in FIG. 4 with only one feed duct 202 leading into the right hand mill portion 204 and one exhaust duct 206 leading from the same mill portion 204, the left hand mill portion 208 having no inlet or outlet.
  • the fluid nozzles 210 of the inlet chamber 212 are identical to those in FIGS. 1 and 4, the nozzles 214 in the chamber 216 are slanted in the same direction as the nozzles 210.
  • the solid particles are fed through duct 202, entrained in the jet streams from nozzles 210 and a portion thereof, consisting of the lighter particles, pass upwardly through the central upstack 216, as indicated in the drawings.
  • the remainder kicks over into the chamber 216 of the mill portion 208 and is further accelerated by the force of the jet streams from the nozzles 214. They then pass through the stack 218, in turbulent stream, where they pulverize each other in the same manner as in the ordinary single mill.
  • the stream then passes through the elbow portion 220 and a portion thereof descends through the upstack 216 to impact with the portion of the particles ascending therethrough together with the ascending fluid from the nozzles 210, the
  • any of the above-described apparatus can also be used for effective mixing of different types of particles as well as for coating particles whereby the particles to be coated are projected from one side and the coating material from the other so that coating is effected by impact under the high velocities present.
  • particles can be metalized or cold-welded together.
  • This apparatus may also be used for the removal of liquids and for dehydrating, especially if additional heat is provided. Such additional heat energy may be provided by heated elastic fluids or auxiliary heating means.
  • Apparatus for treating solid particles comprising at least two generally arcuate mill portions connected by a common stack forming part of each mill portion, at least one mill portion having an inlet for feeding solid particles to be treated into the mill in a selected path and an outlet for exhausting centrifugally separated relatively light particles resulting from the treatment from the mill, each mill portion having an inlet chamber, a plurality of nozzles in each inlet chamber, each of said nozzles being in fluid communication with a source of fluid under pressure, the nozzles in each inlet chamber being constructed and arranged in such manner that each nozzle is at a different angle relative to said selected path of feed of the solid particles than the nozzles adjacent thereto, the angles of the nozzles varying gradually from one nozzle to the next.
  • each mill portion is provided with an inlet and outlet, the outlet in each mill portion being positioned at approximately the juncture between an arcuate classification section and a corresponding downstack leading to the corresponding inlet chamber, each classification section extending between and merging with said common stack at one end and the corresponding downstack at the opposite end.

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  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Disintegrating Or Milling (AREA)
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US703647A 1968-02-07 1968-02-07 Multiple section fluid energy grinding mill Expired - Lifetime US3508714A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4198004A (en) * 1978-05-05 1980-04-15 Aljet Equipment Company Jet mill
US4219164A (en) * 1979-03-16 1980-08-26 Microfuels, Inc. Comminution of pulverulent material by fluid energy
US20090165974A1 (en) * 2007-12-28 2009-07-02 Weyerhaeuser Co. Methods for blending dried cellulose fibers
US20090242672A1 (en) * 2008-03-25 2009-10-01 Albus James F Jet mill
WO2018121803A1 (en) 2016-12-28 2018-07-05 Houdek Jan Device and method for micronization of solid materials

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2054395A5 (no) * 1970-04-06 1971-04-16 Fluid Energy Processing
JPH0667492B2 (ja) * 1986-09-12 1994-08-31 日清製粉株式会社 ジエツト気流式粉砕機

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2237091A (en) * 1937-05-29 1941-04-01 Thermo Plastics Corp Pulverizing apparatus
US2325080A (en) * 1938-10-15 1943-07-27 Thermo Plastics Corp Method and apparatus for comminuting or drying materials
US2550390A (en) * 1944-08-25 1951-04-24 C H Wheeler Mfg Co Method for treating fuel
US2735626A (en) * 1955-01-03 1956-02-21 trost

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2237091A (en) * 1937-05-29 1941-04-01 Thermo Plastics Corp Pulverizing apparatus
US2325080A (en) * 1938-10-15 1943-07-27 Thermo Plastics Corp Method and apparatus for comminuting or drying materials
US2550390A (en) * 1944-08-25 1951-04-24 C H Wheeler Mfg Co Method for treating fuel
US2735626A (en) * 1955-01-03 1956-02-21 trost

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4198004A (en) * 1978-05-05 1980-04-15 Aljet Equipment Company Jet mill
US4219164A (en) * 1979-03-16 1980-08-26 Microfuels, Inc. Comminution of pulverulent material by fluid energy
US20090165974A1 (en) * 2007-12-28 2009-07-02 Weyerhaeuser Co. Methods for blending dried cellulose fibers
US20090242672A1 (en) * 2008-03-25 2009-10-01 Albus James F Jet mill
US7832664B2 (en) * 2008-03-25 2010-11-16 Albus James F Jet mill
WO2018121803A1 (en) 2016-12-28 2018-07-05 Houdek Jan Device and method for micronization of solid materials

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CH477231A (de) 1969-08-31
GB1238737A (no) 1971-07-07
DE1814944A1 (de) 1969-08-21

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