Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS FO ~R S~3PA~ATIMG HEAVY SOLIDS
AND LIGHT SOL:CDS FROM A MIXTURE: THEREOF
Description
sackground of the Invent on
This invention relates to the separation of mixtures
of solids according to the density of the solid components,
_par~icularly where the proportion o~ hea~y solids to the total
amount of solids is relatively small. I~ particularly re-
lates to apparatus for separating heavy solids and light
10 solids from mixtures thereof, which apparatus includes an air
jig with a driven vibrating or ~jigged~ carrier and a means
for separating the heavy fraction from the air jig which is
contaminated with some light material, into a clean heavy
fr~ction and a light fraction according to density.
1~ Prior Art
: Such devices are known as shown, for example, in
German patent No. 623320 of Novem~er 28, 1935. In that patent,
the means for separating the heavy fraction comprises a
current of air blowing transverse to the material to be
20separated as it free falls through the air current- The
lighter particles are carried the greatest distance by the
air current, while the relzitively heavier particles fail out
closer to the air current. One disadvantage of this apparatus
is that while it is intende.d ~o separate according to den~ity,
25it can do so successfully only if the heavy and the light
- material have substantially the same particle size and shape.
In many, perhap~ most, cases, the~e prerequisi~es do not exist
since each ~omponen~ of the mixture has a more or less wide
particle size variat{ on an~ differe~nt par~icle shapes . ~ccord-
30ingly, a cIeax ~eparation of heavy solids material from light
solids material is not possible under th~se conditions. In
order to obtain a ~lear separation, addi~ional devices axe -
required! thus increasi~g the cost.
; Still another d~vice is ~hown in German published
35patent application P 27 0l 345.2-24. The apparatus disclosed
in this application compri~es an air ~ig having i roll-off
separator in the ~orm of an incl~ned conveyor belt. The dis-
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advantage with this device is that the shape of the particle
becomes the essential separation criterion rather than density
and, as such, there are a limited numher of applications for
the device. This device, for example, wo:rks best with solid
5 particle mixtures where the heavy materia:L has a round form .
and the relatively lighter material a flat form, such as the
chips used for manufacture of chip boards which may be mixed
with sand and rocks. There i.s also difficulty with th:is
apparatus in that despite careful lateral covering of the
conveyor belt and even the provision of a cleaning device on
the top surface of the botto~l run therevf, some of the material
being worked upon works its way betwsen the belt and the ~ :
bottom guide or the bottom roller (usually the driving roller)
thus jamming the belt.
~ 15 Summary of the Invention
In general terms, the present invention provides, in an
apparatus for separating a mixture of heavy particulate material
and light particular material into separate fractions of heavy
and light material comprising first and second separating means,
~0 said first separating means heing an elongated air jig, means
for vibra~ing the air jig, and means for discharging the clean
light raction of material from one end of said air jig, the
improvement comprising: lateral discharge means for discharginq
the heavy fraction (which heavy fraction still contains some
light material) from the air jig laterally thereo; said second
separating means being positioned laterally of said air jig to
receive the heavy fraction containing some light material dis-
charged from the air jig by said lateral discharge means; said
second separating means being a pneumatic table having a top
plate onto which said heavy fraction is discharged, said
pneumatic table being capable of separating said heavy fraction :
into clean heavy particles and lighter particles due to the
~ different densities; said pneumatic table being mounted to said
air jig for a vibratory conveying action for conveying the
heavy particles of said heavy fraction received from the air
jig toward one end of said pneumatic table to provide a clean
heavy particulate fraction; means for providing an air stream
in a direction generally opposite to the direction of movement
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o~ the clean heav~ particl2s on said ~neumatic table which air
stream conveys the lighter particles of said heavY Eraction in
said opposite direction; and means for recycling the lighter
particles of said heavy fraction from said pne~natic table
back to said air jig~
The present device is, therefore, ~irected to over-
coming these technical difficulties by providing a separating
apparatus for separating heavy particulate material from
light particulate material in a mixture thereof where the
heavy material is ini~ially a relatively small portion of the
mixtureO The appara~us comprises an air jig with a driven
vibrating or jigged material carrier a~d a means for separating
the heavy fraction from the air jig a~cording to density in
such a way that the device is trouble free, costs are reduced
and there is achieved an improvad separation of the heavy from
the light material. Furthermore, this separation is achieved
'r independently of the shapes of the particles.
To solve this problem, the present invention provides
a pneumatic table to which the hea~y fraction from the air jig
,is directed f~r further ~separation according to density. By
the cooperation of the air jig and the pneuma~ic table, the
.~ charactexistic~ of the two units complement each other so well
that even a very small portion of heavy material may be suit-
ably separated and high throughputs achieved with the air jig.
.The air jig itself provides a clean light ~raction and the heavy
fraction is charged to the pneumatic table, which then provides
for a very clean separation of the heavy ma~erial from the
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1 remaining light material. The light material from the pneu~
matic table is then again charged to the air jig.
The throuyhput capacity of th~s pneumatic table
itself is low since its operating principle is such as to
5 operate upon a s~ngle layer of grains or particIes. However,
it can be so adjusted as to be adap~ed optimally to the heavy
-material fraction from the air jig which fraction is small in
amount so that large total throughputs 1with a very clean
separation of heavy material from light material can be
10 obtained. Still further, relatively small heavy particles
that are included in the charge to the pneumatic table ~rom
the air jig and which are mixed with light material will,
because of their small particle size, be pushed ~ogether into
a high concentration on the pneumatic table into a loose heap
15 which then behaves as if the particles were somewhat larger
so that this loose heap or compact mass when recycled to the
air ~ig is discharged toge~her with the larger particle heavy
material. This effect can be utilized advantageously if, as
described above, the light material discharged Prom the pneu-
20 matic table which still contai~ some heavy material is chargedagain onto the air jig, thus leading to a concentration of
heavy particles in the heavy fraction of the air jig, and
enhancing the described ~gglomeration effect.
Advantageously from the standpoint of cost and space
25 requirements, the pneumatic table may be connected to the
vibrating carrier of the air jig so that a separate drive and
foundation are not required. It has been found that there is
a sufficiently wide range of vibrating parameters with which
the air ~ig and the pneumatic table can operate quite wéll
: ~ 30 simultaneously.
Brief Description of the Drawin~s
The construction and operation of the device will be
apparent to those skilled in the art from the following de-
scription and the accompanying drawing~, in which:
FIG. 1 shows a slde elevation of ~he appara~us;
FIG. 2 shows a plan Yiew of the apparatus;
FIG. 3 shows an enlarged view of the pneumatic table
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1 in Plevation in accordance with FIG, l;
~ IG. 4 shows an end eleva ion of the pneumatic table
generally in the scale of FIG. 3 taken looking from left to
,right in FIG. l; and
5' . FI~. 5 shows a further enlarged cross-sectisn
` through the top plate of the pneumatic table in the area of
~the circle A of FIG. 3.
etailed Description of ~he Preferred Embodiment
The mixture of solid particles to be separated,
10 which comprises a light particulate material with which a
relatively smaller portion of heavy particulate material is
mixed, is ed to the air jig l at charging station 2 from
whence it is fed by the vibration of the carrier 4 onto the
screen bottom 3 of the carrier 4. ~igged material carrier 4
15 is a vibrating conveyor supported by rods 5 pivoted at one end
to the base 6 and at their other end pivoted to the sides of
air boxes lO which, in turn, are secured to the carrier 4
below the screen 3. The ends of the rods 5 may be mounted
by shock absorbing rubber bushings (not detailed) to suitable
20 stub shafts S'. Also secured to the base 6 is a driving motor
7 connected by belt 7' to an eccentric 8' which has pivoted
thereto 2nd eccentric of i~s axis a connecting rod 8 which is
pivoted at its other end to a depending structural element
: . lO' depending,from and secuxed to one of the air boxes lO.
. ''Air for separation of particulate material in accord-
ance with known principles of air jigs (hereinafter called
jigging air~ is,~upplied intermittently through lines ll con-
nected by two connec~ers 9 to the aix boxes lO. When the
motor 7 i~ operated and the air is ~upplied intermi~ently as
30 mentioned above, the material carrier 4 move~ in 'a slight arc
back and forth, as indicated by the arrow 26, which motion
. together with the jigging air results in a sinking of the heavy
: ~aterial.wi~h ~he light material arranged in a top layer over
the he~vy material which, in turn 9 re~ts u~on screen bottom 3.
35 This top layer oiE ligh~ material i~ m~ved by the vibrating of
the carxier 4 ~oward and over the w~ir 12 and then onto the.
B ~. di~charge chute 13. ',,
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1 The heavy fraction of the particulate material is
directed by a guide bar 14, which is of lesser h~ight than the
weir 12. The guide bar 14 is o~ screen bottom 3 and directs
..or deflects ~he heavy fraction to a di~charge opening 15 in
the side wall 16 of the material carrier 4. This is accom-
plished by the obligue position of the guide bar 14. The heavy
~fraction which con~ains some light mater:ial thus passes
through the opening 15, down the chute 17 and onto the top
plate 20 of the pneumatic table 18.
This pneuma~ic table 18 is secured laterally on the
jigged material carrier 4 and comprises a square box 19 with
the plate 20 secured to the top thereof. Conduit 21 connects
to the box 19 to provide a supply of working air. A chute 22
discharges clean heavy material and a discharge pipe 24 is
15provided for the discharge of material falling through the top
plate 20. The longitudinal axis 25 of the pneumatic table
extends parallel to the general direction o~ movement, indi- :
cated by the arrow 126 in FIG. 2, of the jigged material ~
carrier 4. The pneumatic table 18 is secured in a generally
U-shaped mount 27 and may be adjus~ed about its longitudinal
axis 25, in order to influence the distribution of the material
over the width of the top plate 20. The mounting of the
. pneumatic table 18 to the U-shaped mount 27 may be accomplished
: in any of a number of conventional ways, it being only neces-
~: 25SarY that the mounting provide for adjustability of the pneu-
matic table, as indicated by the arrows 28, about the axis 25.
One such mounting arranyement i5 shown as comprising threaded
studs 25' secured to the opposite walls of the box 19 and
passing through one of th~ flanges o.f Ithe angle irons which
30make up the U-shaped frame 27~ Nuts 26^ may then ~e threaded
- upon the ~hreaded studs 25' and tightened ~o secure the
pneumatic table 18 in its desired position'about the axis 25.
For a~ditional securement, second nuts~ like nuts 26', may be
threaded upon the studs 25' as lock nuts. As mentioned, other
3sarrang~ments for eecuring thè table 18 in an adjustable manner
abou~ the axis 25 a~e contemplatedO rrhe solid line and dashed
line positions t shown in FIG. 4, indicate but two of the pos-
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1 sible adjusted positions for the table 180
A laterally extending stub shaft 29 is secured tothe U-shaped frame 27, by welding or the like, and is arranged
with its axis 30 perpendicular to the longitudinal axis 25.
5 The stub shaft 29 i9 received within a bushing 31 rigidly
. connected, by welding or the like, to the carrier 4. The
stub shaft 29 is secured within th~ bu~hing 31 by any suitable
means, such as the set screw 31' which i~ threadedly engaged
in a threaded opening in the bushing 31 and bears agains~
10 the stub shaft 29. A knurled head on ~he se~ screw 31'.per-
mits hand-tightening of.the set screw 31', although.the same
may be tightened by wrench or some other tool, if desired.
Other means of securing the stub shaft 29 within the bushing
31 after adjustment about the axis 30 are con~emplated, and
15 any number of conventional securements, will be apparen~ to
those skilled in the art. In FIGo 3 ~ the solid line and
dashed line positions are but two of the possible positions
for adjustment of the pneumatic table 18 about the axis 30.
The top plate 20 comprises a commercialiy availab}e
20ribbPd trapezoidal screen which has in its cross section the
form shown in FIG. 5. Air supplied through the conduit 21 .
may be adjusted by the throttle valve 34 and after passing
thro-~gh the box 19 it issues through the top plate 20 in the
direction indicated by the arrows 35.in FIG. 5. That is to
say, it is direc~ed upwardly and toward the rear of the
apparatus (~oward the xight in he figures). The special
~hape and arrangement of the openi~gs in the top plate 20, as
shown in FIG. 5, insures that the air travels. in the direction
i~dicated by the arrow 35 which is generally in the opposite
30direction to the dir~ction in which the heavy material frac-
tion i8 being conveyed by the . effects of the vibra ing c~ r
4. The openings in ~he top plate 20 are caused by up-struck
ribs 33. The fractions of heavy and light material separa~ed
on thepneumatic table 18 are conveyed in opposite directions.
35The heavy material is discharged through chute 2~ and removed
for further use, which removal may be effecte~ by any suitable
means, such as a conveyor no~ ~hownO
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1 Small heavy material portions which may have dropped
through the opening~ in the top plate 20 are discharged
pneumatically with a part of the working air through the dis-
charge pipe 24. The cross-sectionAl area of the discharge
5 pipe 24 is so selected or adjusted that the disch~rged par-
ticles have only a ve~y low veloci~y ancl thus may be trapped
~in a simple open container or, if desir~d, fed to the rest of
the heavy material issuing from the chute 22.
The light mater:ial separated by the pneumatic table
10 18, which may still contain small portions of heavy material,
and, in particular, small sized heavy particles, is moved by
the air issuing through t~le plate 20 and in part by the vibra-
tion of the table 18 toward the chute 23 which discharges this
raction onto the inclined conveyor belt 36, which then moves
15 it upwardly and charges it to the air jig, again over the
chute 37.
It will be seen that by use of the appara~us described
above, xelatively high throughputs may be achieved for the air
jig or vibrating carrier 1 with the clean light (and larger
20 quant~tyl fraction being clischarged over the chute 13. The
smaller quantity o~ heavy fraction which may have some light
~: material mixed therewith is then separated on the pneumatic
table resulting in a clean heavy fraction being discharged from
the chute 22. The lîght material, which may ~tilL have some
. 25 heavy material mixed therewith, is then recy~ledO
It will also be seen that by securing the pneumatic
table 18 to the carrier 4 that certain advantages are achieved
in that a separate drive ~s not required nor is a special or
separate feeding devi~e neces8ary for feeding the material to
30 the pneumatic table. Also, the adjustment~ pro~ided for the
pneumatic table permit adjustment o~ the same in order to
achieve the op~imum ~eparation for a variety of diffQrent
particulate material mixtures.
While the openlngs produced by the ribs 33 in the
.; 35 plate 2û guide. the air in the dir~ctlon of the arrows 35 in
; the preferred arrangement, it is po~sible to utilize the plate
20 and ~he pneuma~ic ~able 18 with the air issuing vertically
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1 upwardly perpendicular to the plate 2Q. Also, it is possible
to vary the size of the openings in the top plate 20, since
there are a variety of sizes available commercially in these
ribbed trapezoidal screens. Alternatively, for certain appli-
~ cations, it may be desired to have several hole widths in
: . the same plate.;.
By proper adjustment vf the working air through the
throttle 34 a sifting effect may be achieved which is very
effective for separating according ~o density. As indicated
10 aboYe,.this is generally adjusted so that part of the heavy
particles are carried.along with the light materlal for re
cycling, thus resulting in a very clean heavy fraction. The
heavy material returned with the light material to the air jig
enhances the previously mentioned agglomeration effect of the
15small heavy particles on t:he pneumatic table.
Tf desired or necessary, a suction hood may be posi-
tioned above the pneumatic table for dust removal.
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