US3869090A - Comminuting apparatus and method - Google Patents

Comminuting apparatus and method Download PDF

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Publication number
US3869090A
US3869090A US381594A US38159473A US3869090A US 3869090 A US3869090 A US 3869090A US 381594 A US381594 A US 381594A US 38159473 A US38159473 A US 38159473A US 3869090 A US3869090 A US 3869090A
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Prior art keywords
particles
ground
rotor
grinding
extremity
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US381594A
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English (en)
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Jacques Roussel
Georges Perrin
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Air Liquide SA
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
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Air Liquide SA
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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
    • B02C23/00—Auxiliary methods or auxiliary devices or accessories specially adapted for crushing or disintegrating not provided for in preceding groups or not specially adapted to apparatus covered by a single preceding group
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C13/00—Disintegrating by mills having rotary beater elements ; Hammer mills
    • B02C13/14—Disintegrating by mills having rotary beater elements ; Hammer mills with vertical rotor shaft, e.g. combined with sifting devices
    • B02C13/18—Disintegrating by mills having rotary beater elements ; Hammer mills with vertical rotor shaft, e.g. combined with sifting devices with beaters rigidly connected to the rotor
    • B02C13/1807—Disintegrating by mills having rotary beater elements ; Hammer mills with vertical rotor shaft, e.g. combined with sifting devices with beaters rigidly connected to the rotor the material to be crushed being thrown against an anvil or impact plate
    • 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
    • B02C19/18—Use of auxiliary physical effects, e.g. ultrasonics, irradiation, for disintegrating
    • B02C19/186—Use of cold or heat for disintegrating

Definitions

  • ABSTRACT An apparatus for breaking-up or pulverizing particles of solid material, comprising a 'pulverizing chamber defined by a wall having substantially a shape of mm lution with respect to an axis; at least one rotor disposed coaxially in the interior of said pulverizing chamber and comprising a substantially cylindrical body provided with centrifugal flow means for the particles to be pulverized, said means being uniformly distributed angularly with respect to the axis of said chamber, each flow means extending radially from an internal extraction extremity for said particles to be pulverized, located in an axial receiving zone for said particles, up to an external projection extremity for said particles, located at the outer periphery of said rotor, each said centrifugal flow means having a front surface (with respect to the direction of rotation of said rotor) for displacement of said particles; means for introducing said particles to be pulverized into the axial receiving zone of said rotor; an
  • the invention also covers a method of utilizing this apparatus comprising the further step of recycling at least part of said pulverized particles by fluidization with a carrier gas in a separation and collection chamber and thence to the pulverization chamber.
  • the present invention relates to the grinding of particles of solid material. It is more particularly concerned with a method and apparatus for grinding operating by centrifuging and projection of the particles against a target.
  • a grinding device of the above type has already been proposed, as for example in French Pat. No. 1,370,993, which comprises the following elements:
  • a relatively-flat grinding chamber comprising a wall which is cylindrical or has a form of revolution with respect to a vertical axis, and two flat walls, an upper wall and a lower wall.
  • a rotor arranged coaxially inside the grinding chamber comprising a body and a cover both substantially cylindrical and forming between each other an annular substantially flat space.
  • the cylindrical body is provided with metallic wear bands, angularly displaced in a periodic manner with respect to the axis of the grinding chamber, and clamped between grooves in the said body and the cover.
  • Each wear band is curved with a constant radius and is arranged symmetrically with respect to a radius of the rotor, the concavity of the said band being turned toward the exterior of the rotor.
  • each wear band differentiates each wear band into a front portion and a rear portion (according to the direction'of rotation) which are symmetrical with respect to a radius of the rotor and are substantially straight and radial.
  • the front portion of each band plays the part of a centrifugal flow means for the particles to be ground, extending radially from an internal extraction extremity of the said particles, located in an axial zone of the rotor ensuring the reception of the particles to be ground, to an external projection extremity for the said particles, located at the outer periphery of the rotor.
  • at least the front portion of each wear band has a relatively smooth front surface for the sliding and movement of the particles.
  • each ban cooperating with the front portion of the next following wear band (in the direction of rotation of the rotor) plays practically no part in the centrifugal flow of the particles to be ground, but essentially permits the flow of the said particles to be channelled.
  • the rear portion of one band and the front portion of the next following band form in fact a closed gutter for the radial circulation of the particles towards the exterior, having a section which decreases from the interior towards the exterior of the rotor.
  • each wear band substantially straight and radial, distributed angularly in a uniform manner with respect to the axis of the said chamber, play the part of centrifugal flow means for the particles to be ground.
  • An introduction means for the particles to be ground into the grinding chamber coupled to the upper wall of this latter, comprising a vertical conduit surmounted by a funnel arranged coaxially with the rotor so as to permit direct communication with the axial reception xone of the said rotor.
  • a tangential evacuation means for the ground particles coupled to the lower wall of the grinding chamber, in communication with the peripheral grinding zone in the vicinity of the annular target.
  • a driving shaft for the rotor passing through the lower wall of the grinding chamber.
  • the particles of the material to be ground are introduced vertically into the grinding chamber by means of the vertical introduction conduit, provided with its funnel. In this way, the particles introduced into the axial reception zone of the rotor are brought in by gravity.
  • the particles to be ground are then accelerated in a horizontal plane and flow by centrifugal force along each front portion of each wear band, following a substantially straight and radial trajectory, from the internal extraction extremity located in the axial reception zone up to an external projection extremity located at the periphery of the rotor.
  • the flux of particles to be ground is channelled during the course of centrifuging, in the gutters formed by the co-operation of a front portion and a rear portion belonging to two different wear bands.
  • the radially accelerated particles are then projected at high speed from the external projection extremities towards the annular target.
  • the particles of the material treated are then ground by impact and collision with this target, the ground particles are then removed from the peripheral grinding zone in the vicinity of the annular target, and are evacuated from the grinding chamber through the tangential outlet.
  • the apparatus and method previously described make it possible to convert the mechanical energy applied to the driving shaft of the rotor to kinetic energy imparted to the particles with good efficiency.
  • this proposal effectively recognizes that between 10 and 15% of the theoretical kinetic energy of the particles (calculated at the outlet of the rotor) is lost by friction between the wear bands and the particles to be ground. The efficiency of the grinding by impact on the annular target is thus correspondingly diminished.
  • the invention thus proposes a substantial reduction, and in certain cases practically an elimination, of the friction of the particles to be ground against the centrifugal flow means of the acceleration rotor of the material to be ground.
  • the invention is based on the finding that the considerable friction of the particles to be ground against the centrifugal flow means results from the fact that the profile of the front displacement surface of each flow means moves away considerably from the natural trajectory of centrifuging of the particles to be ground.
  • This natural trajectory depends on the characteristics of the rotor (especially on its physical characteristics, such as its surface condition, its geometry, and more particularly its radius), on the physical characteristics of the particles to be ground (in particular on their form, roughness, etc.), on the kinematic characteristics of the particles treated at the moment of their contact with the rotor (especially the distance of the point of contact with respect to the axis of the rotor, the direction, sense and absolute value of their speed). and on the kinematic characteristics of the rotor (especially its speed of rotation).
  • this trajectory has an essentially concave profile, the running tangent of which, that is to say the tangent at any point of the trajectory, is always to the rear with respect to the direction of rotation of the rotor.
  • the present invention proposes to apply this teaching to the design of appropriate centrifugal flow means of the rotor.
  • each centrifugal flow means comprises a blade having a front displacement surface which has an entirely concave profile along the centrifuging trajectory of the particles to be ground, from an internal extraction extremity located in the reception zone for the particles of the rotor to an external projection extre'mity located at the periphery of the rotor, the concavity of this profile being turned in the direction of rotation of the rotor.
  • centrifuging trajectory predetermined by the profile chosen for the front displacement surface of each blade.
  • This trajectory is generally very close to the natural. centrifuging trajectory, as previously defined, but it may be coincident with this latter when the profile chosen is strictly identical with the natural trajectory when strictly established by any appropriate means.
  • centrifuging trajectory is therefore entirely concave from the internal extraction extremity up to the external projection extremity.
  • the running tangent of this trajectory is always directed towards the rear with respect to the direction of rotation of the rotor. 1
  • the particles to be ground circulate at the surface of the rotor from one extraction extremity to a projection extremity, with a friction which, if it is not brought to zero, is at least reduced to a minimum value.
  • FIG. 1 is a half axial section of a grinding device according to the invention
  • FIG. 2 is a view looking on the top with parts broken away, of the grinding device shown in FIG. 1.
  • FIG. 3 is a plan view of the cylindrical body of a rotor forming part of the grinding machine shown in FIGS. 1 and 2;
  • FIG. 4 is a diagrammatic plan view ofthe rotor shown in FIG. 3 so as to explain its geometric and kinematic characteristics
  • FIG. 5 shows in diagrammatic manner a grinding device incorporating a grinder such as shown in FIGS. 1 to 4;
  • FIG. 6 shows diagrammatically a grinding apparatus similar to that shown in FIG. 5, incorporated in a fluidization recycling circuit
  • FIG. 7 shows diagrammatically a grinding apparatus comprising a recycling circuit such as that shown in FIG. 6;
  • FIG. 8 shows diagrammatically another grinding apparatus comprising a recycling circuit such as that shown in FIG. 6;
  • FIG. 9 is a diagramatic view of another grinding apparatus comprising a recycling circuit such as that shown in FIG. 6;
  • FIG. 10 shows another grinding apparatus in accordance with the invention.
  • FIG. 11 shows still another grinding apparatus according to the invention.
  • a grinding device indicated by the general reference number 200 and intended for grinding particles of a solid material, comprises the following elements:
  • a grinding chamber 501 defined by a wall having generally a form of revolution with respect to a vertical axis, and comprising a horizontal upper wall 200a, a lower wall 200b inclined downwards, and also a cylindrical lateral wall 203 gripped between the upper wall 200a and the lower wall 200b by means of screwsand bolts 701;
  • a rotor 201 arranged coaxially in the interior of the grinding chamber 501, comprising a cylindrical body 504 and a cover 503 having an upper axial orifice 505.
  • the cover 503 is held at a distance from the body 504 by screws 700 and forms with this latter a substantially annular space 702.
  • the cylindrical body 504 shown in FIGS. 3 and 4 is provided with centrifugal flow blades 506 for the particles to be ground, distributed angularly in a uniform manner with respect to the axis 502 of the grinding chamber 501.
  • Each blade 506 extends radially from an internal extraction extremity 506a of the particles to be ground, located in an axial reception zone 507 for the said particles, up to an external projection extremity 506b for the particles to be ground, located at the outer periphery 508 of the rotor.
  • Each blade 506 also has a front surface 5060 (according to the direction of rotation 509 of the rotor) of displacement of the particles to be ground, and a rear surface 506d for grinding the flow of the material to be ground.
  • the front sliding surface 5060 has a substantially circular profile and is thus entirely concave along the trajectory of the particles to be ground, from the internal extraction extremity 506a to the external projection extremity 506b.
  • the concavity of this profile is turned in the direction of rotation 509 of the rotor.
  • the profile of the front surface 5066 is substantially tangential to the outer circular periphery 508 of the rotor, this profile and this periphery forming between them an angle (1 comprised between 0 and Similarly, at the internal extraction extremity 506a, the profile of the front displacement surface 506C is substantially tangential to the internal circular periphery 510 of the axial reception zone 507, this profile and this periphery forming between them an angle a,, comprised between'O" and 10. As shown in FIGS. 1 to 3, the rear face 506d of a given blade and the front face 5060 of the following blade (according to the direction of rotation 509), the cylindrical body 504 and the cover 503 form a closed flow gutter 511 for the material to be ground.
  • a vertical coaxial conduit 515 for the introduction of the particles to be ground coupled to the upper wall 20001 of the grinding chamber 501, in communication and vertically in line with the axial reception zone 507 of the rotor.
  • An annular grinding target 203 inclined downwards and provided with indentations 203a, fixed on the lateral wall 203, arranged inside the grinding chamber and surrounding the rotor 201.
  • a tangential evacuation conduit 512 coupled to the lower wall 200b of the grinding chamber 501, communicating by means of the inclination of the lower wall with the peripheral grinding zone adjacent the annular target.
  • a driving shaft 204 for the rotor passing through the lower wall 200b of the grinding chamber 501.
  • the driving shaft 204 of the rotor 201 co-operates with gaseous guiding and/orsupporting means, such as a labyrinth 220', arranged and coupled to the lower wall 200b of the grinding chamber.
  • the grinding chamber 501 then communicates with vacuum-creating means (not shown in FIG. 1) through the intermediary of the conduit 513, a calibrated gaseous passage being ensured through the labyrinth 220.
  • a feed hopper 250 for the particles to be ground is mounted above the grinder 200 and its grinding chamber. This hopper is provided at its lower extremity with an orifice 229 closable by a gate, ensuring the extraction of the particles to be ground.
  • the hopper 250 communicates with the introduction conduit 515 of the grinder 200 through the intermediary (in the direction of circulation of the particles to be ground) of an intermediate hopper 222 which communicates at its upper extremity with the feed hopper and is provided at its lower extremity with an orifice 224 closable by a gate 260 and ensuring an intermediate extraction of the particles to be ground, and with a rotating distributor 209 arranged between the lower orifice of the intermediate hopper 222' and the introduction conduit 515.
  • a separation collector or cyclone 210 for the ground particles which may be mounted inside the grinder, communicates at its upper portion with the grinding chamber of-this latter, and more exactly with the peripheral grinding zone.
  • the cyclone 210 is provided at its lower portion with a closable cone 252 for the recovery and extraction of the ground particles.
  • the lower extremity of the cyclone 210 is in communication by a valve 283 with a recovery vessel 280 for the ground particles, which may furthermore be kept undr an atmosphere by a conduit 281 provided with a valve 282;
  • the driving shaft of the rotor is driven by a motor 281 and a coupling 221.
  • the grinding apparatus shown may be intended to work at low temperature, for example so as to make plastic materials brittle for grinding.
  • the feed hoppers 222 and 250, the grinding chamber or grinder 200, the introduction and! evacuation conduits 515 and 512, the separation collector 210, are arranged in a thermally insulated casing 225.
  • a circulation passage for a heat-exchange fluid is arranged in thermal contact at 234 with the separation collector 210, especially with the recovery and extraction cone 252, and at 233 with the evacuation conduit 512 of the grinding chamber.
  • This heatexchange passage communicates at one extremity with an inlet 235 of the heat-exchange fluid (gaseous nitrogen for example) and at the other extremity by a conduit 240 with an injection and distribution device (241, 242, 243) for the cooled fluid, arranged in the feed hooper 250.
  • a circulation passage for a refrigerant fluid (liquid nitrogen for example) is arranged in thermal contact at 207 with the introduction conduit 512, at 233 with the intermediate hopper 222, at 226 with the feed hopper 250.
  • This passage communicates at one extremity with an inlet 208 of regrigerant fluid and at the other extremity with an injection and distribution device 228 arranged in the feed hopper 250.
  • the grinding apparatus may be intended to work under the adjustable pressure lower than atmospheric pressure.
  • the conduit 513 with a variable flow-rate in communication with the labyrinth 220, is coupled to a vacuum pump 211'; a conduit 230 with a variable flow-rate 231 communicates with a vacuum pump 232, and a conduit 273 with a variable flow-rate 274 communicates with the pump 232.
  • the pressure is regulated to a value less than atmospheric pressure and preferably comprised between torrs and 200 torrs.
  • the intermediate hopper 222 is brought to atmospheric pressure, the valve 229 is opened, a given quantity of particles to be ground is introduced, the valve 229 is closed, and by means of the pump 232 the pressure in the intermediate hopper is brought to its regulation pressure, lower than the atmospheric pressure.
  • the particles to be ground are then introduced progressively into the introduction conduit 515.
  • the particles to be ground are then introduced vertically into the grinding chamber 501 (see FIGS. 1 and 2) in the direction of the arrow fl.
  • the particles thus introduced are then led by gravity into the axial reception zone 507 of the rotor 201, in the direction of the arrow f2.
  • the rotor 201 being given a movement of rotation (direction 509), the particles thus brought in are then accelerated horizontally in the direction of the arrowf3 during their flow by centrifuging (see FIGS. 3 and 4) from an internal extraction extremity 506a to an external projection extremity 506b.
  • the particles thus accelerated are projected from an external extremity 506b towards the annular target 203 and its indented surfaces 203a, and in this way the particles projected by impact on the target 203 are ground.
  • the ground particles are removed from the peripheral grinding zone in the vicinity of the annular target 203, in the direction of the arrows f4 along the inclined wall 200b, and the ground particles are evacuated from the grinding chamber 501 through the tangential evacuation conduit 512.
  • the ground particles evacuated from the grinder 200 then pass into the separation collector or cyclone 210.
  • the particles are then recovered and extracted in the conical portion of the cyclone 210.
  • the valve 283 is opened towards an extraction vessel 280, previously put under vacuum. This vessel is filled, the valve 283 is closed, and the vessel 280 is opened to air in order to recover the ground particles.
  • the nominal conditions of operation of the grinder have been previously specified as a function of the physical and kinematic characteristics of the rotor and of the particles of the material treated.
  • the front sliding surface 506a of the blades 506 was determined and shaped especially as a function of the natural centrifuging trajectory of the particles for the speed of rotation chosen for the rotor, and for the absolute speed chosen for the particles coming into contact with the rotor.
  • the particles of the material treated reach an internal extraction extremity 506a with the absolute inlet speed C
  • the speed C is generally horizontal and radial; taking account of the nominal speed of rotation of the rotor, the tangential inlet speed 14, at the internal circular periphery 510 of the axial reception zone 507 determines the existence of a relative input speed w equal to the vector difference between the absolute speed C and the tangential speed u
  • the relative input speed w at the internal extraction extremity 506a is tangential to the said front surface.
  • the particles to be ground are then moved and slide along the front surface 5066.
  • the latter move along the blade 506 without appreciable friction.
  • the relative speed w remains substantially tangential to the centrifuging trajectory and equal in absolute value to its initial value w,, from the extraction extremity 506a to the projection extremity 506b, while the tangential speed it of the rotor increases progressively between these two extremities.
  • the relative output speed W2 is substantially tangential to the external periphery 508 of the rotor.
  • the tangential outlet speed 14 and the relative outlet speed W2, the latter being substantially equal in absolute value to the relative inlet speed w are added together as a vector sum so as to give an absolute outlet speed C, at the projection extremity 50612 which is essentially tangential to the external periphery 508 of the rotor.
  • the particles thus accelerated are then projected at the absolute outlet speed 0 on the impact faces 203a of the annular target 203, at the surface of which the grinding of the particles is effected.
  • the relative speed w at the inlet 506a of the rotor is substantially tangential to the front displacement profile 506a. This means that the introduction of the particles on the rotor is effected practically without shock, and therefore without loss of speed;
  • the nature of the particles to be ground may of course vary, whereas the profile of the front displace ment surfaces of the blades remains fixed by construction.
  • the same trajectory of centrifuging is retained for the particles, and therefore the same kinematic conditions at the inlet and the outlet of the rotor, by regulating at the internal extraction extremities 506a, the absolute speed of reception C of the particles to be ground, and/or the speed of rotation of the rotor, so that the relative reception speed w, of the particles with respect to the rotor is tangential to the centrifuging trajectory pre-determined by the profile of the front face 5060 of the blades 506.
  • the absolute speed of reception c can be varied in different ways. According to the invention, the operation is preferably carried out in the following manner. With reference to FIG. 5, the pump 21] acts by suction through the labyrinth 220' to produce the passage of a variable flow of gas, circulating with the particles to be ground in the introduction zone 515 towards the grinding chamber 501 of the grinder 200; this flow of gas is finally introduced into the grinding chamber 501.
  • the pressure of the gaseous regulation flow is chosen as a function of the following conditions. In order to avoid increasing the energy losses of the grinder by stirring up the gas with the rotor of the grinder (fan effect), this pressure must not be too high. On the other hand, in order to obtain an easy regulation of the absolute speed of reception c of the particles on the rotor, the pressure of the gas must not be too low, in order to maintain a viscosity of the gaseous flow compatible with an effective dynamic action of the regulating gas on the particles.
  • the maintenanceof a pressure lower than atmospheric pressure, comprised between 10 torrs and 200 torrs, in the introduction zone 515 of the grinder constitutes an optimum value for substantially attenuating the fan effect of the grinder while retaining a good dynamic action of the gas on the particles and thus ensuring convenient regulation of the absolute reception speed 0
  • the regulating flow of gas must not be too large so as not to increase the cost of the corresponding equipment for creating vacuum, and not to increase the fan effect of the rotor.
  • the absolute reception speed c, ofthe particles on the rotor 201 must be as low as possible so as toavoid the necessity of using an excessive flow of gas for accelerating the particles.
  • a single passage through the grinder 200 is not sufficient to reduce the particles to be ground to ground particles of pre-determined dimensions. Furthermore, for mechanical reasons, it is often desired to limit the speed of rotation of the grinder below a maximum speed, which involves the existence of a maximum grinding efficiency, and the necessity of proceeding in certain cases to a number of passages of the product to be ground through. the grinder 200. For all these reasons, it may be necessary to proceed to one or more recycling operations of the particles ground in the grinder.
  • the present invention proposes to carry out the recyclingotf the ground particles by fluidization and pneumatic conveyance by means of an appropriate carrier gas.
  • the recycling circuit proper integrates the grinding chamber 501 of the grinder 200, its introduction conduit 515 and its evacuating conduit 512, the separation. collector or cyclone 210 arranged outside the grinding chamber 501, the feed-hopper 250.
  • Theseparation collector 210 is arranged on the outside of the grinding chamber, at an average level higher than that of the feed-hopper 250. It communicates at its upper portion by an evacuation conduit 516 with the evacuation means 512 for the ground particles, and at its lower portion with the introduction means 515 of the particles to be ground through the intermediary of a flow conduit 517, of the feed-hopper 250, and of a rotary distributor 520 arranged between this latter and the introduction conduit 515.
  • the feed-hopper 250 provided at its lower extremity with the rotary distributor 520, communicates at its lower extremity with the introduction means 515 of the grinding chamber 501.
  • the flow conduit 517 communicates on the one hand with the lower cone 252 of the separation collector 210 and on the other hand with the feed hopper 250.
  • This recycling circuit is associated with circulation means for a carrier gas (for example nitrogen) on the outside of the grinding chamber 501 from this latter towards During recycling, a flow of the carrier gas passes through the calibrated leakage 521 into the introduction zone 515 downstream ofthe rotary valve 521, under a pressure P
  • this adjustable pressure, maintained in the introduction zone 515 is comprised between 10 torrs and 200 torrs, and the flow of gas introduced through 521 assists in the regulation of the absolute inlet speed of the particles to be ground in the grinder 200.
  • the pressure P is lower than the pressure P,-, but higher than the adjustable pressure P maintained in the collection and separation zone 210.
  • the ground particles are recyl5 cled by fluidization with the carrier gas in an upward direction inside the separation and collection chamber 210.
  • the adjustable pressure P maintained in the 2() feed chamber 250 is lower than the adjustable pressure P, maintained in the collection and separation chamber 210.
  • the ground particles are carried away by fluidization of the collection zone 210 towards the supply zone 250.
  • the introduction zone 515 is caused to communicate with the feed chamber 250, and the ground particles are introduccd into the introduction zone 515 towards the grinding chamber 501.
  • the operating pressure P P P P and the working pressure P,. of the vacuum pump can be chosen in any otherwise it is impossible to recycle the ground product by fluidization.
  • -Qv is the flow-rate of gas drawn-in by the pump 518;
  • -Qf is the flow-rate of leakage gas, in counter-flow to the recycling direction, through the rotary valve 520 of the introduction zone 515 under high-pressure towards the supply zone 250 under low pressure;
  • Qr is the flow-rate of gas carried away by rotation in the direction of recycling by the rotary valve 520 playing the part of a gas circulator
  • -Qe is the flow-rate of gas circulating from the collection zone 210 towards the'supply zone 250, through the conduit 517.
  • the grinding or pul- 50 verizing apparatus shown comprises an evacuation cyclone or extraction means 527 for the ground particles, communicating with an upper outlet 410 of the cyclone 210, that is to say on the downstream side of the grinding chamber 501 of the grinder or pulverizer 200, and on the upstream side of the introduction means 515 of the said chamber, according to the direction of recycling of the ground particles.
  • the feed-hopper 250 which is not incorporated in the recycling circuit, plays the part of a supply means for the particles to be 60 ground, by means of another rotary valve 530 arranged between the said hopper and the introduction means 515 for the particles to be ground.
  • the feed-hopper 250 being arranged outside the recycling circuit, the rotary valve 520 ensuring the circu- 5 lation of the ground particles from an upstream portion at low pressure to a downstream portion at high pressure, is directly arranged on the extraction conduit 517 at the at the lower portion of the cyclone 210.
  • the extraction cyclone 527 for the ground particles communicates with a reception vessel 405 for the pulverized product.
  • a motor 525 drives the grinder 200; another hopper 526 for cooling the product to be pulverized communicates with the feed-hopper 250.
  • a cooling circuit similar to that shown in FIG. 5, ensures the circulation of a refrigerant fluid introduced at 208 into the feed-hopper 250, the introduction conduit 515, the evacuation conduit 516, and the separation collector 210.
  • the refrigerant fluid is finally evacuated into the cooling hopper 526.
  • the putting under vacuum is carried out through filters 270 by vacuum pumps (not shown).
  • a sorting means for the pulverized particles is incorporated in the collector 210, and comprises the upper outlet 410 for relatively-fine powdered particles, ensuring the extraction of the ground particles to the extraction cyclone 527, and a lower recycling outlet for relatively-large particles, communicating through the rotary valve 520 with the flow conduit 517 connecting together the separation collector 210 and the introduction means 515 of the grinding chamber.
  • the grinding or pulverizing apparatus shown in FIG. 8 is similar to that shown in FIG. 7, and comprises a recycling circuit incorporating the supply chamber 250 (as shown in FIG. 6). It is also provided with a circulation conduit for a refrigerant fluid introduced at 208, which cools the introduction conduit 515 and the supply hopper 250. The fluid is finally evacuated into the hopper 526. Part of the residual gas is extracted in order to provide the calibrated gas leakage introduced below the rotary valve 520 into the introduction zone 515.
  • the extraction means or extraction cyclone 527 communicates with the evacuation conduit 516 arranged between the grinding chamber 501 or grinder 200 and the separation collector 210, by means of a change-over device 528 comprising a recycling position 529 to the collector 210, and an evacuation position 530 towards the extraction means 527.
  • the grinding apparatus shown in FIG. 9 comprises a recycling circuit identical with that shown in FIG. 6, incorporating the supply or feed-hopper 250.
  • the separation collector 210 is provided with a sorting means 407, the evacuation outlet 410 of which communicates with a receiving vessel 234 for the pulverized product and the recycling outlet 409 of which communicates with the flow conduit 517.
  • a lock-chamber hopper 222 provides a communication between the feed-hopper 250 and a cooling hopper 526.
  • the apparatus is provided with a cooling circuit having an inlet 208 and an outlet 228 into the hopper 526, and with a heat-exchange circuit in which the inlet 235 enables the cold to be recovered in the vessel 405, and the outlet which is arranged in the hopper 526.
  • FIG. 10 a grinding apparatus according to the invention which makes it possible to obtain progressive pulverization of the particles to be ground.
  • This apparatus comprises a first upper rotor 201a having a relatively-small radius and a last lower rotor 201b having a relatively-large radius, arranged inside the grinding chamber 501, mounted for rotation on the same driving shaft 204.
  • Each rotor comprises a plurality of flow blades (506a and 506!) respectively) extending radially from an axial receiving zone for the product to be ground (507a and 507b respectively), the dimensions of which are substantially identical for the first and last rotors 201a and 201b, up to the periphery of the corresponding rotor.
  • the grinding chamber 501 further comprises a means for transfer of the pulverized product by gravity from the peripheral grinding zone 203a associated with the rotor 201a, towards the axial receiving zone 507b of the next following rotor 20lb.
  • the axial receiving zone 507a of the first rotor 201a communicates with the introduction means 515 of the product to be ground by a gutter 104, while the peripheral grinding zone 20312 associated with the last rotor communicates with the evacuation means 512 for the pulverized prod uct.
  • the grinding chamber 501 communicates with the supply hopper 250 by a lock-chamber provided with valves 15 and 16, while the grinding chamber and the evacuation conduit 512 communicates with each other through a lock-chamber provided with valves 9 and 10.
  • Vacuum-creation means comprise a pump 232 communicating at' 19, 22 and 20 with the two lockchambers and the grinding chamber 501.
  • a conduit 208 for the circulation of a refrigerant fluid enables the grinding and pulverizing apparatus to be cooled.
  • FIG. 11 there is described a grinding apparatus in tended to work at low temperatures, without the addition of refrigerant fluid such as liquid nitrogen.
  • This apparatus comprises a grinder 200 identical with that described in FIGS. 1 to 4, and therefore comprising a rotor 201 arranged in a grinding chamber 501, an annular pulverizing target 203, a driving shaft 204 for the rotor, an introduction means 515 for the particles to be ground and an evacuation means 512 for the pulverized particles.
  • An expansion turbine 550 mounted on the driving shaft 204 of the rotor, is associated with a closed gas circuit for the compression and expansion of a gas, comprising a compressor in which the suction 55lb under low pressure communicates with the outlet 55012 of the expansion turbine 550, and the delivery 5510 of which communicates with the inlet 550a of the turbine.
  • the passage conduit 552 for the expanded and cold gas is in heatexchange relation at553 with the annular target 203, and the wall of the grinding chamber 501, and at 554 with the introduction means 515 of the particles to be pulverized.
  • expansion turbine 550 and the grinder 200 may be provided as one single component, when the rotor of the turbine 550 and the rotor 201 of the grinding chamber are combined in one unit.
  • the present invention can be applied to the grinding and pulverization of any material at ambient temperature or at low temperatures.
  • a wall having substantially a shape of revolution about an axis and defining a grinding chamber
  • each of said centrifugal flow guide means extending radially from an internal extremity for the extraction of said particles to be ground, located in an axial receiving zone for said particles, up to an external extremity for the projection of said particles, lo-
  • each of said centrifugal flow guide means having a front surface with respect to the direction rotation of said rotor for displacement of said particles, said front displacement surface having a concave profile from said internal extraction extremity to said external projection extremity of said particles to be ground,
  • annular impact means disposed in said grinding chamber, and surrounding said rotor
  • each said centrifugal flow guide means forms an angle comprised between and with said outer circular periphery of said rotor
  • each said centrifugal flow guide means forms an angle comprised between 0 and 10 with the inner circular periphery of said axial receiving zone.
  • a wall having substantially a shape of revolution about an axis and defining a grinding chamber
  • at least one rotor disposed coaxially within said grinding chamber, comprising: a body having a shape of revolution about said axis centrifugal flow guide means for the particles to be ground, secured to said body, uniformly distributed angularly about said axis, each of said centrifugal flow guide means extending radially from an internal extremity for the extraction of said particles to be ground, located in an axial receiving zone for said particles, up to an external extremity for the projection of said particles, located at the outer circular periphery of said rotor, and each of said centrifugal flow guide means having a front surface with respect to the direction of rotation of said rotor for displacement of said particles, said front displacement surface having a concave profile from said internal extraction extremity to said internal projection extremity of said particles to be ground, 3. means for introducing said particles to be ground, in communication with said axial receiving zone of said rotor,
  • annular impact means disposed in said grinding chamber, and surrounding said rotor
  • evacuation means for said ground particles in communication with a peripheral grinding zone, adjacent to said annular impact means, and
  • each said centrifugal flow guide means has a profile, from said internal extraction extremity to said external projection extremity, substantially close to the natural centrifuging trajectory of said particles to be ground under the working conditions of said rotor and said particles.
  • each said centrifugal flow guide means forms an angle comprised between 0 and 10 with said outer circular periphery of said rotor
  • each said centrifugal flow guide means forms an angle comprised between 0 and 10 with the inner circular periphery of said axial receiving zone.
  • Apparatus according to claim 1 wherein said apparatus works under an adjustable subatmospheric pressure, wherein said driving shaft rotates on gas bearing means comprising a guiding member secured to said wall of said grinding chamber and defining with said driving shaft a calibrated gaseous passage, and wherein vacuum-creating means are connected to said grinding chamber through said calibrated gaseous passage.
  • a grinding device comprising:
  • said apparatus is adapted to work under an adjustable subatmospheric pressure, and so has the further following features:
  • said supplying means comprise a feed hopper under atmospheric pressure, and a depressurizable intermediate hopper, both disposed verti cally,
  • said intermediate hopper has upper and lower closure means, said upper closure means communicating with said feed hopper for the introduction of said particles to be ground, and said lower closure means communicating with said rotary distributor for the extraction of said particles to be ground, and
  • vacuum creating means to communicate on the one hand with at least said intermediate hopper, and on the other hand through flow-rate adjusting means and at least a filter with at least said grinding chamber, said introducing means, said evacuation means of said grinding device, and said separating means.
  • a grinding device comprising:
  • a classifying separator for said ground particles disposed outside said grinding device, having an inlet for said ground particles, a first outlet for ground particles of larger size, and a second outlet for ground particles of smaller size, and
  • a circuit for the pneumatic recycling of said ground particles of larger size comprising:
  • gaseous circulation means for circulating cyclically a carrier gas from said evacuation means of said grinding device to said introducing means of said grinding device, through said evacuation conduit and said classifying; separator, and
  • a carrier gas separator for separating said ground particles of smaller size from said carrier gas, having an inlet communicating with said second outlet of said classifying separator, an outlet for said carrier gas, and an outlet for said ground particles of smaller size;
  • said supplying means comprise a feed hopper under atmospheric pressure, and a depressurizable intermediate hopper, both disposed vertically,
  • said intermediate depressurizable hopper has upper and lower closure means, said upper closure means communicating with said feed hopper for the introduction of said particles to be ground, and said lower closure means communicating with said rotary distributor disposed between said supplying means and said introducing means of said grinding device,
  • said gaseous circulating means are vacuumcreating means, communicating on the one hand with said intermediate hopper, and on the other hand through at least one filter with said outlet for said carrier gas of said carrier gas separator, and
  • said outlet for said ground particles of smaller size of said carrier gas separator has a closable orifice communicating with a recovery vessel for said ground particles of smaller size.
  • a grinding device comprising:
  • separating means for said ground particles disposed outside said grinding device, having an inlet communicating with said evacuation means of said grinding device, and an outlet for said ground particles, and

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  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Crushing And Pulverization Processes (AREA)
  • Crushing And Grinding (AREA)
US381594A 1972-07-27 1973-07-23 Comminuting apparatus and method Expired - Lifetime US3869090A (en)

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JP (1) JPS4967253A (it)
BE (1) BE802811A (it)
CA (1) CA1009202A (it)
DE (1) DE2337969A1 (it)
FR (1) FR2194132A5 (it)
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IT (1) IT992664B (it)

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US4418871A (en) * 1981-07-15 1983-12-06 P.V. Machining, Inc. Method and apparatus for reducing and classifying mineral crystalline and brittle noncrystalline material
US5392997A (en) * 1993-12-08 1995-02-28 Comensoli; Inaco Non-impact pulverizer and method of using
US5816509A (en) * 1997-08-26 1998-10-06 Korea Atomic Energy Research Institute Apparatus for continuously supplying fine powder in minute and quantitative amounts
CN103143429A (zh) * 2013-03-29 2013-06-12 河南省四达仙龙实业有限公司 一种粉碎机的上壳
CN106694179A (zh) * 2016-08-18 2017-05-24 无锡市稼宝药业有限公司 一种农药生产用粉碎装置
CN109157996A (zh) * 2018-11-16 2019-01-08 四川亿欣新材料有限公司 一种碳酸钙粉末分散方法
CN117619523A (zh) * 2023-11-16 2024-03-01 惠州市高斯强电子有限公司 一种钕铁硼永磁体的加工工艺及加工设备

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US4697743A (en) * 1982-12-13 1987-10-06 Sicomant Ab Juteskarsgatan 38 Method of finely crushing particles of material in an impact mill and apparatus for performing the method
FR2577445B1 (fr) * 1985-02-15 1988-05-27 Framatome Sa Dispositif de projection de particules solides pour broyeur centrifuge sous vide
WO1989007042A1 (en) * 1988-02-05 1989-08-10 Erema Engineering-Recycling-Maschinen-Anlagen Gese Device for processing thermoplastics
US5597123A (en) * 1995-06-30 1997-01-28 Praxair Technology, Inc. Ultra-high energy cryogenic impact system
US5860605A (en) 1996-10-11 1999-01-19 Johannes Petrus Andreas Josephus Van Der Zanden Method and device for synchronously making material collide
DE19714075A1 (de) * 1997-04-04 1998-10-08 Hosokawa Mikropul Ges Fuer Mah Mahlanlage
DE102008049339B4 (de) 2008-09-29 2020-07-16 Pallmann Maschinenfabrik Gmbh & Co. Kg Vorrichtung zum Bearbeiten von Aufgabegut
CN105344417A (zh) * 2014-08-21 2016-02-24 李桂清 一种复式高效节能破碎机
HUE058246T2 (hu) * 2014-12-09 2022-07-28 Frewitt Fabrique De Machines S A Vákuum õrlõrendszer és eljárás
US11596949B2 (en) * 2017-06-21 2023-03-07 Biodryingtech Spa High-speed dewatering and pulverizing turbine
CN110013900B (zh) * 2019-04-28 2024-01-12 河北工业大学 一种核桃壳粉碎设备
CN112138784A (zh) * 2020-08-28 2020-12-29 湖南新食康农业发展有限公司 一种红薯粉生产用磨粉装置
CN113289714B (zh) * 2021-05-19 2022-08-26 黄石海纳新材料科技股份有限公司 一种超细轻质碳酸钙制备专用高效研磨机
DE102021125313A1 (de) * 2021-09-29 2023-03-30 Decker Steuerungs- und Regelungsanlagen GmbH Vorrichtung und Verfahren zur Feinvermahlung

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4418871A (en) * 1981-07-15 1983-12-06 P.V. Machining, Inc. Method and apparatus for reducing and classifying mineral crystalline and brittle noncrystalline material
US5392997A (en) * 1993-12-08 1995-02-28 Comensoli; Inaco Non-impact pulverizer and method of using
US5816509A (en) * 1997-08-26 1998-10-06 Korea Atomic Energy Research Institute Apparatus for continuously supplying fine powder in minute and quantitative amounts
CN103143429A (zh) * 2013-03-29 2013-06-12 河南省四达仙龙实业有限公司 一种粉碎机的上壳
CN106694179A (zh) * 2016-08-18 2017-05-24 无锡市稼宝药业有限公司 一种农药生产用粉碎装置
CN109157996A (zh) * 2018-11-16 2019-01-08 四川亿欣新材料有限公司 一种碳酸钙粉末分散方法
CN117619523A (zh) * 2023-11-16 2024-03-01 惠州市高斯强电子有限公司 一种钕铁硼永磁体的加工工艺及加工设备

Also Published As

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BE802811A (fr) 1974-01-28
DE2337969A1 (de) 1974-02-07
JPS4967253A (it) 1974-06-29
GB1434420A (en) 1976-05-05
IT992664B (it) 1975-09-30
CA1009202A (en) 1977-04-26
FR2194132A5 (it) 1974-02-22

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