Note: Descriptions are shown in the official language in which they were submitted.
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~ I APPARATUS AND METXOD FO~
4 I -- CLASSIFYING PARTICLES
s !
6 1i a~b~
7!¦ This invention relates to tne classificstion of
~ll particulate matter and, especially, to improvements in
q'l v~bratory and gyratory apparatus and processes for classifying
101l particles in accordance with size, mass, density and the like.
Related Patents
3 1l The present invention is useful in connection with the
14 I concepts disclosed in my earlier U.S. Patents Nos. 4,148,725
lS,I and 4,3l9,995.
16 11 ,
17¦¦ Back~round of the Invention
18 ¦l . In gyratory, vibratory and reciprocal type ~eparators,
19¦l or "classifiers," the particulate matter to be classified forms
~20¦' a particle bed ~on a supporting surface that is agitated with a
21 I gyratory, cyclical or repetitive motion. The gyratory type
22 1 devices disclosed in ~he above U.S~ patents ~,148,725 and
23 ¦ 4,l19,995, for example, classify particles of given size
241l¦ accordin9 to their relative densities.
25 11 '
1 26ll Gyratory separators conventionally ~ave been used to
271i classify particles in accordance with size. A typical
28 ! separator classifier is disclosed in U.S~ Patent No. 2,~50,819,
~911 in which the particle mixture is placed upon a vibratory screen
301, designed to pass particles of all sizes smaller than the ~creen
129(17~4
1¦1 openings~ Such gyratory screening classifiers, are operatea
2 I such that oversize particles ordinarily move to the periphery
3 I of the screen and are discharged. Particles which are smaller
4 ' than the screen openings fall through into a collection chamber
5 ~ from which they may be extracted.
6 l li
7 Gyratory classification devices, when used to classify
8 ¦ particles according relative density, can be effective
¦ classifiers; however, a significant problem has been ~heir
10 ¦ limited processing rate. Specifically, such devices have
11 inherent limitations restricting the rate or flow of material
1' to be classified. Attempts to increase the flow rate by
13 speeding up the frequency or intensity of gyratory motion tends
lL I to impede the further flow of particles from the feed hopper
15 ¦ into the working chamber where the separation occurs. On the
16 I other hand, attempts to add particles to th~ feed hopper at a
171¦ faster rate only reduces the degree of fluidization of the
18 ¦¦ particle bed and, ultimately, separation simply stops. That
19¦¦ is, when material is introduced too ~uickly, the particles ',
20¦~ exhibit a significant reduction in activity, which can be
21 ¦ observed as a packing of the partirle bed.
22
23 ¦ In screening operations, i.e., size classifications,
24 ¦ problems are often encountered with very fine particulate
25~1 matter, such as epoxy powdered material as fine as about 2;0
26li mesh. This problem is generally manifested as a "blinding" of
27 ~ ~he screen. When blinding occurs, the holes of the screen
28 ¦ become blocked and no longer permit passage of the fines.
29 ¦ Conventional gyratory screening classifiers make use of a
30 ¦ gyratory container carrying a horizontal screen upon which
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3~ o~ 1
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Ii . ,
Il ,
l I particles to be classified are placed. As mentioned a~ove,
2 ¦¦ those particles which are finer than the screen openings f~
~1! through into a lower chamber for collection or removal. Coarse
4 I particles are ordinarily extracted at the periphery of the
5 ¦ screen. These conventional devices sometimes make use of
6 ¦ "scrolls" to increase the residence time of particles on the
7 ~ screen. To con~rol the activity of particles on the screen,
8 I the components of gyratory motion can be adjusted.
Adjusment of gyratory motion is accomplished by (a)
11 altering the size and relative angular position of the throw
~ weights at ~he top and bottom of the drive mo~or and/or (b) by
13 varying the speed of the motor. As a general rule, the bottom
14 ¦ weight tends to control the amplitude of the vertical
15 1 displacement of gyratory motion, whereas the top weight tends
16 to control the degree of eccentricity of the motion when the
17 welghts are angularly displaced. In operating screening
18 classifiers, the object is to present the particles to the open
l9 apertures of the screen as frequ~ntly as possible so that the
fines can drop through the apertures before leaving the
21 screen. In order to achieve this object, a balance must be
22 1 struck betwe~n the flow rate through the machine and
23 ¦ classification efficiency. Attempts to increase the throughput
24 rate in conventional screening devices have generally resulted
2S ¦ in reduced screening efficiency; conversely, attempts to
26 I improve efficiency have generally required a reduced rate of
27 1 throughput.
2~ ,
29 Similarly, in density classiication in which the '
object is to separate dense or higher mass particles from the
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1 ,
1ll bed~ the feed rate which can be achieved without overloaaing
2 1 the particle bed or diminishing the residence time unaccep~ably ,
3 I has been restricted. It was found that increasing the
4 ¦ frequency of gyration often merely caused particles to back up ~l
5 I into the feed hopper. The reason for this behavior of the
6 ~ particles is not completely understood, but appeared to be the
7 result of an increase of pressure in the classification head
8 j due to the increased counter throw of the b d supporting
9 ~ sur~ace.
lo
11 Summary of the Invention
~ 1' ¦ The prese~t invention improves particle classification
1 13 I methods by permitting a higher degree of fluidization of the
i~ particle bed, by permitting higher flow rates to be used at a
15 ! given efficiency, and by achieving better efficiency at a given
1 16 ¦ flow rate. Briefly, this is accomplished by enhancing the
17 ¦ kinetic energy (i.e., activity) of particles before they enter
18 ¦ the classification chamber, such that the particles to be
19 1 introduced overcome the apparent resistance set up by particle
20 ' activity within the classification chamber. The present
¦ inv~ntion also induces the particles entering the
22 I classification chamber to move in a direction counter to the
23 ¦ direction of the thrust, or "throw" of the particle-supporting
2~ ! suxface of the bed.
26 I The preferred means for accomplishing this comprises
27 I an "activation chamber" wh:ich is shaped to enhance the particle
28 I activity therein, with an i.ncrease of the apparent "pressure"
29 ¦ or energy of the particles.
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1 In the case of gyratory motion, the activation chamber
2 takes the form of an annulus, or circle, because the locus of the
3 horizontal eccentric motion component of the gyratory motion is
4 circular. In its cross-section the annulus may be merely
rectangular, but preferably the cross-section is defined by a
6 vertical thrusting surface and lateral surfaces convergent toward
7 an exit aperture. This exit aperture is preferably located in
8 proximity to a particle thrusting surface at the interior of the
9 classification chamber. Activated particles are dispersed over
the particle bed in a direction counter to the throw induced by
11 the particle bed supporting surface. If the classification
12 motion is primarily reciprocal (back and forth) in the horizontal
13 plane, the activation chamber may be linear, rather than annular.
14
As a result of preactivating the particle feed entering
16 the classification chamber, classification can be carried out at
17 higher repetitive motion frequencies so as to obtain greater
18 particle activity and a higher degree of fluidization of the
l9 particles resident in the classification chamber. Such increased
fluidization is attended by a greater recovery of classified
21 particles, i.e., higher yield, and by a capa ity for increased
22 rates of particle flow.
23
24 In a broad aspect, the present invention relates to an
apparatus for classifying particles and having a screen for
26 separating undersized particles from a mass of particles carried
27 thereby, the apparatus having means for imparting gyratory motion
28 to the screen, said motion having a laterally eccentric component
29 and a repetitive vertical component for fluidizing and resulting
in directions of flow of particles on the screen and providing
31 a radially directed throw. Particularly, the pr~sent invention
J~ ~
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1 provides an improvement comprising: a lid overlying the screen,
2 said lid defining with said screen a classification chamber and
3 providing a reaction surface for contacting active particles in
4 said chamber, said chamber having an exit for oversized particles
located along the circumference of said apparatus; and means for
6 introducing particles into said chamber at a portion thereof
7 located radially distant from said exit, and means for dispersing
8 introduced particles across the surface of the screen toward said
9 exit in a direction opposite to the direction of said throw.
ll In another broad aspect, the present invention relates
12 to an improvement in a gyratory particle classification
13 apparatus, comprising, in combination: a gyratory motion working
14 chamber defined by a particle bed-supporting surface providing
a net radial throw and on which a fluidized particle bed is
16 formed, a lid extending over the particle bed-supporting surface
17 and disposed to contact fluidized particles in said fluid
18 particle bed, the working chamber having an exit aperture for
19 rejected particles; and means for introducing particles from a
particle source into said working chamber which are located
21 radially distant from said exit aperture and which are effective
22 to enhance the activity of source particles entering said working
23 chamber and to disperse the activated particles toward said exit
24 aperture into said fluidized particle bed in a direction counter
to the direction of net radial throw, and overcome the resistance
26 of said fluidized particle bed to the introduction of source
27 particles into said working chamber.
28
29 In another broad aspect the present invention provides
apparatus for classifying particulate material, comprising: means
31 for defining a particle classification chamber including a
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1 particle bed-supporting surface on which a fluidized particle bed is
2 formed, a laterally extending surface spaced above the particle bed-
3 supporting surface and an exit aperture for removing excess
4 particulate material; means for imparting to said classification
chamber a repetitive motion having at least a generally horizontal
6 component fluidizing the particle bed and imparting a net
7 directional throw to the particles of said particle bed, and giving
8 a downward motion component to particles contacted by said laterally
9 extending surface; and means for introducing activated particles
into said classification chamber located distant from said exit
11 aperture and to disperse said activated particles toward said exit
12 aperture in a direction counter to the net directional throw and
13 overcome the resistance of the flu.idized bed to the addition of
14 particles thereto.
In another broad aspect th~ present invention relates, in
16 apparatus for classifying particles, to the combination: a working
17 chamber having a generally horizontal surface for supporting a bed
18 of particles, an upstanding surface for contacting and dispersing
l9 particles over said general horizontal surface, an exit aperture
remote from said upstanding surface for contacting and dispersing
21 particles into said bed of particlee, and a lid spaced above said
22 : surface for supporting particles and convergent therewith toward
23 said exit aperture; means for agitating said working chamber with a
24 repetitive motion having a generally horizontal motion component
fluidizing a bed of particles formed on said generally horizontal
26 surface and imparting to said working chamber in the vicinity of
27 said aperture a net throw in a direction counter to the movement of
28 the particles in said working chamber which is in a direction from
29 said upstanding surface for contacting and dispersing particles into
said bed of particles and toward said ------------------------------
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1~9~ 4
1 exit aperture; and a particle activation chamber, located distant
2 from said exit aperture of said working chamber, mo~able with
3 said working chamber and having a particle exit for admitting
4 particles into said working chamber in proximity to said
upstanding surface for contacting and dispersing particles into
6 said bed of particles; said particle activation chamber being
7 shaped to activate and induce in the particles therein a net
8 movement in a direction generally parallel to the locus of the
9 repetitive generally horizontal motion compon~nt.
11 In a further broad aspect the present invention relates
12 to a gyratory apparatus for classifying particles according to
13 size, the apparatus having a frame, a particle supporting
14 classification surface permitting undersize particles to pass
therethrough, and means for agitat.ing said frame with gyratory
16 motion and fluidizing the particles on said particle supporting
17 classification surface and exerting thereon a net radial throw,
18 and to the improvement comprising: a laterally extending lid
19 spaced vertically above said particle supporting classification
surface and defining therewith a classification chamber having
21 an exit aperture for oversize particles; and means located
22 radially distant from said exit aperture for àdmitting particles
23 into said classification chamber and activating and imparting to
24 particles entering said classification chamber a directional
movement which is counter to the direction of net throw of said
26 apparatus, and dispersing said activated and admitted particles
27 toward said exit aperture of said classification chamber.
28
29 In a further broad aspect, the present invention relates,
in a process for classifying the particles in a particle bed
31 within a classification chamber having an inlet and an outlet,
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1 wherein the chamber is agitated with a repetitive motion having
2 at least a generally horizontal motion component for fluidizing
3 the particle bed, to the steps of: providing a source of
4 particles at a given rate to an activation chamber having an
inlet and an outlet for the passage of particles therethrough;
6 agitating said activation chamber with a repetitive motion to
7 enhance the activity of particles passing therethrough from said
8 source of particles; and introducing activated particles into
9 said classification chamber; said activated particlss being
introduced into said classification chamber distant from the
11 outlet thereof and having a directional motion tending to
12 disperse such activated particle6 over said particle bed and away
13 from the location of introduction thereof, and enabling thereby
14 a continuous flow of particles from said source of particles
through said activation chamber and into said classification
16 chamber, said classification chamber having a motion providing
17 a net inward directional throw to particles in the particle bed,
18 and the directional motion of activated particles introduced into
19 said classification chamber being counter to said net inward
directional throw.
21
22 The invention will be better understood by reference to
23 the following detailed description and drawings of the preferred
24 embodiments.
26 Description of th.e Drawin~s
27
28 FIG. 1 is a cut-away perspective view of a gyratory
29
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36~-~G~ l
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l ¦ scre~ning apparatus implementing the present invention;
2 l
3 ~ FIG. 2 is a elevational view in cross-section o~ ~he 1,
4 ¦ working chamber of the gyratory apparatus of FIG. l, taken
S ¦ generally along the line 2-2 in FIG. l;
6 l
7 ! FIG. 3 is a cross-sectional elevational view of a
8 particle separation head incorporating the invention;
9 I i
10 ¦ FIG. 4 is a cross-sectional elevational view of a
11 I further embodiment of the separation head incorporating the
1~ ¦ invention;
13
i4 ¦ FIG. 5 is a partially cut-away perspective view of a
reciprocal motion screening apparatus implementing the present
16 invention;
17 .
18 FIG. 6:is a cross-sectional view in elevation of the
19 apparatus in FIG. 5; and
1.
21 FIG. 7 i:s a schematic representation in elevation of a
22 reciprocal motion apparatus, similar to that of FIG. 4,
23 incorporating the invention and useful in classifying particles
24 according to density.
Z5
26 Description of Preferred Embodiment
27 Referring first to ~IG. l, the apparatus incorporating
28 the invention includes a gyratory separator machine, designated
29 generally by the numeral lO. It will be und~rstood that the
machine lO is a commercial device which functions to impart
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1~907;~4
i
1 , gyratory motion to the classification nead assem~ly 12. The
2 I classification head 12 includes a working chamber equipped to
3 I classify particles according to size. This working chamber
4 comprises a classification surface in the ~orm of a screen 14
5 j carried by a cylindrical frame 16. This frame 16, in turn, is
6 mounted inside a larger cylindrical frame 18 having a floor
7 plate 22 which is solid in the region 22a between the frame 1~ i
8 and rim 20. That region forms a collection channel for coarse
9 particles which do not pass through the screen 14, whereas the
fine particles pass through the screen and through the
11 ¦ perforated area 22b of the floor plate. The coarse particles
1' ¦ travel to the perimeter and exit from the waste spout 21, while
13 the fines are recovered from the spout 24. In the region
1~ between the screen 14 and the plate 22, conventional screen
cleaning elements (not shown) are uced, such elements being in
16 the form of several plastic rings having a height approximately
17 the height of the rim 20, or of small rubber balls of lesser
18 dia~eter.
19 i
20 I In accordance with the present invention, the
21 ! classification head is provided with a laterally extending lid
22 30 which overlies the classification screen 14 and is
23 vertically spaced from it to form a classi~ication chamber 31
24 ~FIG. 2) which, due to the sloping conîiguration of the lid,
generally decreases in cross-se tional area from the center
26 I thereof to the perimeter. This is best observed in the
27 crosssectional view of FIG. 2. The lid 30 is spaced from the
28 screen at its perimiter by spacers (not shown) to form an exit
29 I gap 26 (Fig. 2) which may be on the order o~ 1~16-1/4 inch in
30 I size when classifying typical p;rticulate matter~
;l
307;~4
l I Extending upwardly from the surface of the screen 14
2 is a cylindrical element 32 that ~unctions as a thrusting
3 ~ surface for dispersing particles outwardly over the surface of
the classi~ication screen 14. The cylindxical element 32 is
5 ¦ held in place by a threaded ver ical shaft 33 affixed to the
6 I convex floor plate 35 of an intermediate spacing frame 36
~ I associated with the ~yratory machine lO. Th~ perforated plate
8 ~ 22 is supported at its center by the vertical collar 38, also
9 I affixed to the convex floor plate 3~; a spacer cylinder 39
lO I resting on the perforated plate 22 in turn supports the screen
ll ¦ 14 at its center. To that end, a pair of washer plates 37a,
1~ 3~b clamps the screen and provides a ba~e for the cylindrical
13 thrusting element 32, the entire cylindrical assembly being
l~ ~ecured by a further plate ~0 and nut 42 at the top.
16 For the purpose of feeding particles into the working
17 chamber 31, a feed hopper 4A is integrally a~fixed to the lid
18 30. The feed hopper 44 is cylindrical in cross-section and
19 includes a cylindrical' ring 46 concentric with the element 32
that forms therewith a narrow annular channel 48. This channel
Zl 1 48, which is an importan~ fea~ure in the embodiment of FIGS. 1
22 and 2, has a circular entrance aperture 4ga at the top for
23 accepting particles loaded into the feed hopper, and has a
24 clrcular exit aperture 49b at its lower end for admitting
particles into the classification chamber. This channel 4B
activates the particles accepted from the feed hopper ~nd
27 increases their kinetic energy prior to admitting them into the
28 classification chamber 31. Par~icles adde~ to the feed hopper
29 are retained temporarily u~pon the floor 44a of the hopper. It
will be understood that, when the apparatus is operated, the
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1 ¦ entire classifiGatiQn head assembly 12 assumes a gyratory
2 ¦ motion having both a circularly eccentric motion component and
3 1l a repetitive vertical motion component.
5 I Gyratory motion is impaxted to the classification head
6 ¦ 12 by the gyratory separator machine 10. This machine is a
7 standard commercial unit having a moSlnting base 50, a plurality
8 of compression springs 51 circumferentially spaced about the
9 upper flange 50a of ~he base for supporting a cylindrica$ mo~or
frame 53. This frame in~ludes a horizontal plate 54 that
11 carries at its center a cylindrical motor mount 55 extending
1' down into the base. A motor 56 is supported within the mount
13 by a pair of horizontal flanges 57, 58. Each of the frames 53,
14 36, 18 is secured to its adjacent frame by a clamping ring (not
shown) at its periphery. In this manner, the entire upper
16 ¦ classification section 12 ~oves with the frame 53. Vibrations
I7 ¦ induced by the motor are therefore transmitted directly to the
18 ¦ frame, and to the upper components mounted to it.
19 : 'i
The desir,~d motion is obtained from the eccentricity
2~ o~ the weigh~s 61, 62 a~fixed tc~ the motor shaft. Thes,P
22 weights p~oject horizontally outwardly from the motor shaft,
23 ¦ the radial angle between their axes being adjustable by
24 shifting and locking the angular position of one of the weigh~s
relative to the other weigh~. Thus, the lower weight 62 can be
26 made to lead or lag the position o~ the upper weight 61 by a ~,
27 ~electable angle. Adjustment of these weights alters the
28 charac~eristics of the resultan~ gyratory motion.
29 It was found that good results ar~ obtained when the
_ 9 _
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1;~90~;~4
l ¦ weights are set to provide a displacement angle of 180, with
2 I the lower weight 62 being heaviQr than the top weight 610 In
3 I practice this was accomplished by inverting the motor of an
4 , 18-inch Kason vibratory machine. This brings about a high
S degree of fluidity in the particle bed by causing the frame 53
6 I to exhibit a large vertical displacement at the perimeter. At
7 ~ the same time, a substantial horizontal eccentric motion is
8 ¦ imparted to the frame 53 which, combined with the vertical
displacement, induces a net inward thrust (or "throw") to
~ ~_~
particles contacted by the screen 14.
11 I
1' As is now apparent, the classification head 12 assumes
13 a gyratory motion when the motor is in operation. Such
l~ gyratory motion has both a circularly eccentric component and
15 ~ an oscillatory, or repetitive, vertical component. The
16 I combination of these two motion components enables energy to be
17 imparted to the particle bed t~o achieve the desired
18 fluidization. Fluidization of the particle bed within the
1~ classification head occurs as a result of the instantaneous
spacing between individual particles, as is fully explained in
21 my prior patent No. 4,319,995.
22
23 It is, of course, possible to adjust the weights to
Z4 in~ermediata angular displacements~ It is, however, importan~
25 I that the classification head be given a repetitive horizontal,
26 or lateral, displacement. For gyratory motion, this means that
27 the classification head wi].l have a horizontal eccentric
28 componen~. As hereinafter explained, this horizontal eccentric
29 component is utilized to disperse newly added particles
outwardly into the classi~ication chamber~
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l l
1 I Size Classification O~eration
2 1 In classifying particles it has been found th~t best
3 ¦ results are achieved when particles have a high degree of
4 I fluidization within the classification chamber. This can be
S ¦ observed as an expansion o the inter-particle spacing within
6 ¦ the classification chamber. Increasad fluidization can be
7 ! achieved by increasing th~ frequency of gyr~tion. Howeve , it
has also been observed that as efforts are made to increase the
G 1, motion frequency to enhance fluidity of the par~icles, the flow
0¦1 rate of particles through the apparatus tends to decrease owing
~ to the inability of particles to enter the classification
1, chamber. It appears that the higher the level of activity
13 ¦ within the classification chamber, the less the tendency for
1~ particles to enter the chamber. The reason for this phenomrnon
~5 is not entirely understood; however, it may be analogized to an
16 increase in pressure within the classification head as
17 fluidization increases, this pressure resisting the entry of
18¦ new particles. -
19
In the present invention, the annular channel 48
21 formed between the cylindrical elemen~ 32 and the cylindrical
2~ ~ ring 46 is effec~ive in overcoming this resistance to particle
23 ¦ entry by preactivating particles before they are admitted into
24 I the classification chamber. In the channel 48, the particles
25 I flow in a circular path and also have a complex spinning and
26 bouncing motion. Thus all par~icles entering ~he
27 classification chamb~r 31 have an enhanced level of energy as a
1 28 result of encountering the closely spaced and eccentrically
~9 moving walls of the channel 48.
3~
129U'7~4
l¦l Particles entering th2 classification chamber 31 via
2 ~ the particle-introducing channel 48 are admitted adjacent the
~ ¦ cylindrical element 32 which, by reason of the eccentric motion
4 component, contacts the admitted particles and disperses th m
S outwardly away from the point of entry to make room for the
6 entry of additional particles This outward dispersion of
7 particles is in a direction counter to the direction of the
8 inward throw exerted on the particles by the screen 14 and, in
9 some cases, by the lid 30. Outwardly dispersed particles are
thus forced against other particles thrown inward by the
ll screen. They are also contacted by the lid and driven against i-
l' the screen where the fine and course particles become
13 classified. Due to the preactivation of particles by the
14 channel 48, the frequency and/or intensity of mo~ion can by
stepped up to enhance the activity within the particle bed and,
16 ¦ hence, to enchance the efficiency of operation.
17
18 Density Classification
19 FIG. 3 illustrates the configuration of a
20 classif ication head ~or separating denser particles from the
21 less dense particles of a slze classified particle mixture.
22 This head is mounted directly to the gyratory separator machine
23 ¦ 10. In place of the classif ica ion screen 14 are a number of
24 concentric rings 61-65 each ha~ing at least one narrow vertical
opening so as to form a series of intercommunicating annular
26 channels. Here, the thread2d shaft 33 is affixed directly to
27 tbe floor plate 75. In this configuration (not drawn to
28 scale)l which is described in de~ail in the aorementioned U.S.
29 ¦ Patent No. 4,319,995, a cen~ral collection zone 66 at the
interior of the ring 61, contains a plurality of spaced-apart
- 12 -
lZ90724
l horizontal discs Ç~. These discs maintain fluidization of
2 l particles within the collection zone.
4 I Preactivation of particles by the channel 48 and their
S I outward dispersion by the element 32 occur as described above
6 ¦ in connection with FIGS. 1-2. Particles within the
¦ classification chamber beneath the lid 30' fall into the
8 I annular channels, whereby less dense particles in the central
9 ¦ collection zone are displaced by particles of greater density,
lO I ~he less dense particles flowing outwardly and ultimately over
ll I the frame 16, and into the waste spout 21. The particle 5
1~ ¦ concentrate, consisting o~ a high percentage of particles of
13 greater density, enters a lower collection chamber 72 through
14 extraction ports 74 in the floor plate 75 that supports the
S particle bed. The concentrate is periodically removed by
16 applying a vacuum to the pipe 76~ Alternatively, the
l7 ¦ concentrate may be permitted to fall into a domed lower frame
18 ¦ similar to the frame 36 of FIGS. 1-2 for continuous withdrawal
19 ¦ from an exit spout. The dome of such frame may also be
provided with a series of cs~epped circular ridges to disper~e
21 the concentrate particles toward th 5 periphery where they can
22 be wi hdrawn from a spout, such as the spout 24 in FIG. 1.
23
24 When apparatus constructed as shown in FIG. 3 was
opera~ed, it was found that the frequency and amplitude of
26 gyratory motion could be increased due to activation of the
27 particles in the channel 48. This resulted in a higher degree
28 ¦ of fluidization of the particle bed, attended by a faster rate
29 ¦ of particle flsw through the apparatus, and a higher rate of
O I recovery of dense particle~. 1
I ^ L3 - !
lZ907Z4
1 A further embodiment of the separator configuration is
2 shown in FIG. 4, in which the intermediate activation chamber
3 is shaped to increase the energy level of particles drawn rom
~, the hopper, and to introduce particles into the classification ',
S chamber at a location, and with a direction, aiding the
6 dispersion of particle~ over the particle bed against the
7 inward throw o the machine. (Where appropriate, the same
re~erence numerals have been assigned to like elements).
10 ¦ In FI~. 4, the activation cham~er takes the form of an
11 ¦ annular channel of triangular cross-section overlying the
1~ I uppermost disc 68a, combinded with an upper channel 48" similar
13 I to ch~nnel 48'. The channel 48" is rectangular in
14 ~ cross-section and is formed between the element 32' and the
cylindrical wall section 46'. The channel 48" activates the
16 particles in the manner described above in connection with FIG.
17 3.
18
19 The triangular channel configuration is defined by
three primary surface elements: the horizontal top disc 68a; a
21 ¦ vertical thrusting surface providad by the cylindrical element
22 32'; and an angled, laterally ex~ending segment 80 of the lid
23 30'. These elements also deine an entrance aperture 82 at the
24 top of the triangle where preactivated particles enter the
triangular channel 90 from the upper channel 48", or chamber
26 ~ 48n. The elements 68a and 80 converge from the thrusting
Z7 ¦ sur~ace of the element 32' toward an exit aperture 83 at the
28 opposi~e end of the triangular chamber. The ~oregoing three
29 elements and the entrance and exit apertures together thus form
a second particle activation chamber 90, or compression chambar
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1;~907~4
l I of tapering cross-section which further activates particles
2 ¦ entering the classification cham~er from the upper ac~ivation
3 I chamber 48". Thus, particles flowing into the compression
chamber 90 are driven outwardly and downwardly toward the exit
5 ¦ aperture 83 upon being contacted by the surfaces of el?ments
6 ¦ 32' a~d 80. This results in a further increase in the en~rgy
7 I of par~icles entering the working chamber 31'.
9 The surace of element 32' furthermore functions as a
dispersing surface to contact the activated particles and drive
ll them outwardly against the inward throw exerted on particles by
1~ the elements within the classification chamber. Thus in the
13 embodiment of FIG. 4, the dispersing surface for the particles
14 is integral with the activation chamber.
16 It should be remarked that the annular compression
17 chamber configuration of Fig. 4 is equally advantagaeous when
18 used with the gyratory screening apparatus of Fig. l.
19 Additionally, it is possible to implement a plurality of
annular rings in the position indicated by the phantom lines 91
21 ~ in Fig.4, in order to assist in the feeding of particles into
22 ¦ the en~rance aperture 82. Such rings form annular channels and ',
23 the rings are either ported or are spaced from the hopper floor
26 44a in order to permit particles to flow from the outer
channels to the inner channels.
26
27 The presence of an activation chamber has been found
28 to permit classifying ~o occur at higher gyratory speeds with
29 higher rates of throughput and higher recovery of classified
30 particles~ The following examples are illus~rative. I
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1 ¦EXAMPLE I
2 IThe classification embodiment of FIGS. 1 and 2
3 ~machine Xl) was operated and compared with a standard 18-inch
diameter Kason vibro screening machine (machine ~2), with each
5 , device equipped wi~h screens of identical mesh size. Three
6 ¦ different screen sizes were used; in which a given arnount of
7 ~ sand was fed into each machine until all the sand particles
8 were classified into fines and oversize. The fines and
9 I oversize were weighed and the time taken for classification was
10 recorded. The results were as follows: i
11 I
1' I Test 1: 49 lbs_of -25+30 mesh sand, 30 mesh screen
13 Nachine #1: 19 lbs of fines in 16 minutes
14 Machine #2: 13 lbs of fines in 15 minutes, 50 seconds
Test 2: 50 lbs of -60~170 mesh sand, 100 mesh
screen
16 - -
17 ¦ Machine #1: 14 lbs of fines in 21 minutes, 30 seconds
18 I Machine ~2: 13.5 lbs of flnes in 36 minutes
19 ¦ Test 3: $O5 lbs -170+300 mesh epoxy powder, 250
mesh screen~
21 Machine ~1: 4.~ lbs of fines in 7 minutes
Machine #2: Screen blinded, unable to classify
22 I i
23 ¦ The above qualitative tests indicate the improvements
in classification achieved with ~he present invention.
2~
Specifically, the invention provided either higher throughput,
26 ¦ greater efficiency, or both. Thus, in Test 1, the recovery
27 ~ improved by 46% whereas, in Test 2, the throughput rate ~or the
28 I same recovery increased by 67%. In Test 3, the invention
2~ I perrnitted 96% recovery o~ 250 mesh epoxy powder which, in the
30 I same test, the standard cor~mercial machine was unable to
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11l classify.
2 I '~
3 EXAMP~E I}
An apparatus was constructed as shown in FIG. 4 (but
5 I without the chamber 48") with the following dimensions: ~_
6 ¦ Element Dimens~on
7 surface 80, lengt~ 1.375 inches
8 aperture 82 .25 inchec
9 thrusting surface 32', 1.125 inches (distance
length from aperture 82 to disc 68a)
10 ¦ disc 68a, radius .875 inches (distance from
11 I element 32' to edge of 68a)
1~ ¦ Forty-one (41) pounds of 16+30 sand and 14.5 grams of -16f30
13 iron shot were mixed together. Nine(9) pounds of clean sand
1~ was distributed inside the annular channels between rings
61-64. The motor weights were set at 180 with the weight
16 ¦ distribution being 3 standard Kason small weights at the top
17 ¦ and 4 standard Kason heavy weights a~ the bottom. The motor
18 was started and operated at 1650 rpm, and the sand~shot mixture
~ 19 added to the hopper at the rate of 18 lbs. per minute. Flow
1 20 was cont~nuous through the apparatus unt~l all 50 pounds of
21 ¦~feed~material was depleted and no further flow of waste was
22 observed. The results of the test were as follows:
23 Loca~tion of mater~al Weigùt Sand Weight Iron Shot
24 concentrate withdrawn 8 lbs. 12.0 grams
from collection
chamber 72
26 Channels 2 l~s.1.3 grams
27 Waste 40 lbs.3 grams
28 Total ~Q~I~ }3~!-!a;~
~he foregoing results show a 91.7% ~13.3 grams)
recovery of the iron shot, with .9 grams shot b~ing unaccounted
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l ¦ for. Compared with the apparatus shown in FIGS. 1-3 of U.S.
2 I Patent No. 4,319,995, implementation of the activation chamber
3 ¦ increased the obtainable rate of flow through the apparatus by
4 ¦ a factor of almost 2, and increased the total recovery of iron
5 I shot from the mixture by about 15% in one pass.
6 ~ '
7 ExaMPLE III
8 An apparatus as shown FIG. 3 was constructed and
9 operated under the following conditions:
Element Dimensions
. - .
ll Element 32', diameter 3 inches
1' Ring 46', inside diameter 3.75 inches
13 Ring 46', height 2.25 inches
14 Channel 48, width .375 inches
15 Distance between ring
16 46 and_disc 68a ~750 inches
Exit aperature gap 26' 7125 inch 1,
17
18 Fifty-seven (57) pounds of -16+30 mesh sand was
19 admixed with 15 grams of -16+30 mesh iron shot. The channels
20 (between elements 61-64 and 16) were filled with an additional
21 nine (9) pounds of clean sand. The motor was brought to an
~' 22 operating speed of 1650 rpm~ same weight settings as Example ',
23 ~ II, and the sand/shot mixture was poured to ~he feed hopper 44
24 ¦ at the rate of about 18 lbs. per minute until exh~usted. At
25 ~ that time, with the motor still runnin~, eight pounds of
1~ 26 concentrate was withdrawn from the chamber 7~ in fifteen
27 seconds, leaving two pounds of material in the channels~
28 Durin~ the approximately 3~1/2 minute test, 66 pounds of waste
29 material were ejected. The results are tabulated below: i
301
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1~l L~_a~r ~c ~ee~i~l Weight Sand Weiqht Iron Shot
2 I Concentrate withdrawn8 lbs. 11.6
3 I ~rom chamber 72
Channels 2 lbs1 2.6 grams
S ¦ Waste 66 lbs.
6 Total 76 lbs. 15.0 grams ~
?¦ The recovery of iron shot from the mixture was about 95%.
Reciprocal Motion Classification
10 ¦ FIGS. 5-7 depict the implementation of the invention
11 in classification apparatus using reciprocal, primarily
1~ horizontal motion (as distinguished from gyratory motion) of a
13 particle bed-supporting sur~ace. Referring to FIG. 5, the
i~ apparatus comprises a horizontal rectangular frame 90 supported
at its four corners by hinge fittings 91 for suspension by rods
16 ¦ 92,93 from a cradle (not shown). The entire frame is arranged
17 I for a back and forth reciprocal motion over a limited distance,
18 ¦ e.g., .25-.50 inches. The rods 92 at one end of the frame are
19 ¦ slightly shorter than the rods 93 supporting the opposite end
20 ¦ of the frame~ The frame ~0 is reciprocally moved by a
21 ¦ motor-driven eccentric mechanism ~, illustrated schematically
22 in FIG. 5. As a result of the difference in length between the
23 rods 92,93 a slight lifting motion occurs at the lert end of
24 the frame as the frame moves to the right. The rectangular
25 ¦ frame and drive mechanism is a commercial screening apparatus
26 manufactured by R.I.D. (Switzerland). It should be ~nderstood
27 that the frame 90 can take other forms and can be supported and
28 driven by other means. For example, the entire frame may be
29 supported on roller bearings, slides, rocker arms e~c. It is
further noted that the apparatus shown in the drawings is
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1 I primarily a configuration used to demonstrate the effectiv~ness
2 of the invention when reciprocal linear motion is isolated from
3 ¦ the circularly eccentric component of gyratory motion.
4 l l
5 I As shown in FIGS. 5 and 6, the ~rame supports a screen i-
6 95 suspended generally horizontally over the bottom of the
7 frame, and at each end of the frame is a flate plate 96a, 96b,
8 which may be displaced vertically relative to one another to
9 change the angle of the screen. As shown, the plate 96a is at
10 ¦ a slightly higher vertical elevation than the plate 96b, so
11 ¦ that the screen slopes upwardly from right to left
1~ I . ~.
13 The apparatus includes a feed hopper 97 defined
14 between the back wall 99 of the frame, the frame sides and a
1~ transversely extendin~ vertical wall 98. The hopper, of
16 course, may be made higher or otherwise changed in dimensionO
17 The floor surface 100 of the ~eed hopper is formed with a slot
18 102 communicating with a linear com~ression chamber 103 of
19 triangular cross-section. This compression chamber, or
20 parti~le activation chamberl is bounded by the ver~i~al
21 thrusting wall 104, a horizontal surface element ~05, and a
22 sloping surface lOB extsnding between the entrance aperture 102
23 and an exit aperture 106. A sloping lid 110 supported above
24 the screen 95 and forming therewith a classi~ication chamber
111, extends from the aperture 106 at one end to an elongated
26 exit aperture 115 at the other end. Particles enter the
27 classification chamber at a point adjacen~ the vertical step
28 112, which func~ions as a dispersing sur~ace to propel
29 particles over the particle bed toward the exit aperture 115
and counter the direction of throw provided by the
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1 I bed-supporting screen 95.
3 ¦ In operation, particles to be classified are loaded
4 ~ into the ~eed hopper 97 from which they pass through the
5 ¦ entrance aperture 102 into the activation chamber 103. The
6 reciprocal motion of the frame, and of the elements carried
t therein, results in the contacting of the particles by the
surfaces of the activation chamber in such a way that the
9 particles are caused to be driven toward the aperture 106 and
lQ into the classification chamber 111 formed between the screen
11 95 and the downwardly sloping lid 110. These activated
1' particles are given further thrust, in opposition to the throw
13 of the machine, as they encounter the reciprocally moving
14 vertical dispersing surace 112. Once inside the
15 I classification chamber, the particles are classified according 'i
16 to size by the screen 95. The fines drop through the screen
17 and are collected in the space beneath the screen. Coarse
18 ¦ particles continue to travel away from the dispersing surface
1~ 112 toward the exit aperture 115 at the far end of the sloping
lid 110. Th~ frame includes a channel (no~ shown) for
21 extracting the oversized material.
22 I
23 ¦ The following example illustrates a typical screening
~4 I operation using reciprocal motion.
2S I
26¦ EX~MPLE IV
27 Th~ apparatus was arranged as shown in FIGS. 5-6, with the
28 dimension of the elements as follows:
2~
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1 I Element Dimension
2 ¦ Screen 17 L x 11 W in.
3 ¦ Feed hopper 97 4.5 L x 11 W x 3 H in.
4 I Vertical element 104, height 2.25 in.
5 ¦ Sloping surface element 108 2.75 in.
6 ¦ Entrance aperture 102, gap width 0.5 in.
~ ! Lid 110, length 13 in.
8 Exit aperture 106, gap width 0.5 in.
9 I Horizontal surface 1057 length 2 in.
10 I Thrusting surface 112, height 1 in.
11 Exit aperture 115 0O2 in.
The matPrial to be classified consisted of 37 lbs. of
13 -1/8~1/16 sand. The screen 95 was 1/8 inch square mesh and the
I motor/eccentric drive was operated at 1200 rpm in the direction
¦ shown by the arrow. The sand was poured into the hopper 97 to
16 l, achieve a rate of flow of 12 lbs. per minute. Flow of th~
18 material was uphill and against the throw of the apparatus. At
I the end of approximately 3 minutes, the apparatus was stopped
19 and ~he classified sand was weighed. Fines measured 27 lbs. of
sand (passed through the screen), 1 lb. of sand was recovered
21 I as coarse and 9 lbs. of unclassified sand remained in the unit.
22
23 It should be noted that the activation chamber
2~
opera~es in such a manner that ~he partîcles entering the
classification chamber have a level of activation which assists
2S ¦ in their dispersion against the throw of the machine. The
28 activa~ion chamber is characterized by a geometry such that its
2g movement activates the part:icle and causes them to flow into
~he entrance aperture and out of the exit aper~ure in a
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1 I preferred direction. In the machine shown in FIGS 5 and 6, for
2 ¦ instance, the reciprocal motion of the frame causes the
3 I thrusting surface 104 of the activation chamber to drive
41¦ particles between the convergent elements 105, 108 toward the
5 I exit aperture 106. Thus, as particles are contacted by the
6 ¦ thrusting surface 104, they are simul~aneously "squeezed~
7 ¦ between the surface elements 105, 108, and the small activation
8 I chamber lQ3 accordingly functisns as a compressor. In an
9 ¦ experiment in which the activa ion chamber was reversed
li~ft-to-right, to have its exit aperture facing the dispersing
11 surface 112 rather than the aperture 115, flow through the
1' apparatus was negligible.
13
;~ Turning to FIG. 7, there is shown a scheme for
classifying particles according to density using reciprocal
16 motion. The FIG. 7 apparatus comprises a feed hopper 27, a
17 ¦ triangular activation chamber 128 formed between surface
18 elements 129, 138 and the top plate 140a of a stack of
19 vertically spaced-apart horizontal plates 140. The activation
ZO chamber communicates with the hopper via the particle entrance
21 j aperture 141, and has an sxit aperture 143 for admitting
22 particles into the classification chamber. ~nderneath a
23 downwardly sloping lid 142, a series of mutually spaced
24 vertical baffle plates 144 having vertical slots (not shown) to
2S form a plurality of intercommunications, laterally-extending
26 ¦ channels. These channels allow particles of greater density
27 I (or mass) to enter in preference to particles of lesser
1 28 density. The space between the particle occupying the channels
! 29 and the sloping lid 142 constitut2s a classification chamber, I
the exit 146 of which is between the last vertical baf1e plate
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1 1 144 and the low r edge of the lid.
3 In operation, the frame gO is given a reciprocal
4 motion by the eccentric motor drive, and partic}es are added to
S I the hopper 127, from which they pass through the entrance
6 ¦ apPrture 141 into the astivation chamber 128. Their kinetic
; energy is raised by repetitive contact with the thrusting wall
8 129 and sloping element 138. Preactivated particles thereupon
. ~ enter the classification chamber via the aperture 143, where
: 10 they have a net motion in the direction of the classification
11 chamber exit 146. As particles ~raverse the distance between
12 the activation chamber 128 and the exit 146, they may enter the
13 channels defined between vertical plates 144. Particles
14 striking the sloping lid 142 are driven downwardly into the
channels and, in this case, particles of greater density tend
16 to be driven into the channels in preference to particles of
l7 lesser densi~y, the latter being displaced. The stack of
18 ¦ horizontal plates 140 serves to damp particle activity in the
19 ¦ collec ion zone immediately below the activation chamber. j -
2011 i
21 EXAMPLE V
22 ~ The apparatus of FIG~ 7 was constructed with the
23 following dimensions: ¦
24 ~ Element Dimension
~: 2S Aperture 141 gap width 0.5 inch
26 ~perture 143 gap width 0.5 inch `.
27 Length of sloping surface 138 3 inches s
28 Height of thrusting surface 129 2.5 inches
Z9 Height o~ vertical plates 144 2 inches
Length of horizontal plates 140 2.5 inches
~ ~ 24 -
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1 ¦ Length of lid 142 6.5 inches
2 ~ Area of frame occupied by channels
3 ~ (including plates 140) 72 square inches
4 I Height of aperture 146 0.25 incn
¦ Width of all elements 8.5 inches
S I ij
6 I The foregoing apparatus was operated under the
7 following test conditions: Seven (7) pounds of -1/8+1/16 mesh
8 sand was loaded into the channels prior to the test.
9 Twenty-six (26) pounds of -1/8+1~16 sand was admixed with 15
grams of -1/8~1/16 mesh iron shot. The eccentric motor drive
11 was operated at a speed of 1500 rpm, and the sand/shot mixture
1~ was poured into the hopper at the rate of 14.9 lbs. per
13 minute. At the conclusion of the pour, the followiny
14 measurements were made:
Location of Material ~5~ Weight Lead Shot
16 ~irst channel,
17 among plates 140 3.5 lbs. 4.7 grams
remaining channels 3.0 lbs. 3.9 grams
18
19 ¦ Waste Z6.5 lbs. 6.~ grams
20 I Total 33.0 lbs. 15.0 grams
21 j It is seen that the rate of recovery in this apparatus was
: .
22 approximately 60% from about 72 square inches of channels in
23 one pass. Although this rate of recovery is less than was
24 obtainad with gyratory apparatus, ~eparation was nevertheless
appreciable.
26
27 From the precading, it is noted that the process
28 effected by the invention offers significant improvements in
29 the ability of gyratory and reciprocal equip;.lent to accept
higher rates of flow during classifcation of particles.
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l Moreover, by implementing a classification chamber and by
2 preactivating particles, conventional screening apparatus can
3 be operated at higher throughput rates and with particles
4 I having a degree of fineness which could not previously be
S classified by ordinary methods.
7 Al~hough the invention has been described with
8 reference to the preferred embodiments, it should be understood
19 that certain modifications and variations will occur to those
skilled in the art without departing from the spirit and scope
ll of the invention.
1'
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14
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19
21
22
23
24
26
27
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