study of construction and working of grain separators

1. SEPARATORS
1. Disk separator
2. Indented cylinder separator
3. Spiral separator
4. Specific gravity separator
5. Inclined draper belt
6. Velvet roll separator
7. Magnetic separator
Prof.H.S.Chaudhari
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2. DISK SEPARATOR
 Separation - difference in length.
 pockets or indentations on its surfaces.
 smaller size materials - caught in the pockets
 larger - rejected.
 used for removing the dissimilar material like wheat, rye,
mustard, barley from oats.
 It consists of a number of disks in series fitted on shaft inside
of close housing which revolves on horizontal axis.
 pockets are slightly undercut on each disk, as the disks
revolve through a mixture of grains, the pockets pick up short
grain and drop them into a through at the side of the
machine.
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Prof. H. S. Chaudhari

3. Disk Separator
Disc
Disc in series
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Prof. H. S. Chaudhari

4.  A number of distinct separations of varying length can be made
by installing combination of disk having pockets of different
sizes.
 for only one separation - combination of disks of a same size of
pockets is used.
 The mixture first passes through the disk with small pockets
and then disks with pockets progressively larger from inlet to
discharge.
 three basic shapes disk pockets
 The ‘R’ pocket derives its name from ‘rice’ and was designed to
remove broken rice grains from whole grain.
 The ‘V’ pocket derives its name from ‘Vetch’ and was design to
pick up and remove round shape grains
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Prof. H. S. Chaudhari

5. INDENTED CYLINDER SEPARATOR
 Separation on the basis of relative lengths like disk separators.
 It consists of a horizontal rotating cylinder which has indents on
the inside surface.
 The indents are closely spaced and hemispherical in shape.
 short grains are picked up by the combined effect of fitting into
the indents and centrifugal force.
 dropped into an adjustable trough inside the cylinder.
 A screw conveyor is provided in the bottom of the trough which
conveys the material.
 cylinder is kept at slight inclination to facilitate gravity flow of
long grains in the cylinder. 5
Prof. H. S. Chaudhari

6. Lifting and
dropping of
shorter seeds
into trough
Rejected
long seeds
Adjustable
trough
Conveying
augers
Intended Cylinder Separator
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Prof. H. S. Chaudhari

7. SPIRAL SEPARATOR
 separates as per there roundness.
 The main component of the separator is a stationary, open screw conveyor
standing on one end.
 The mixture is fed at the top of the unit.
 The round materials of the mixture pick up speed as they slide or roll down the
inclined surface, until their centrifugal force becomes sufficient enough to throw
them in the outer helix.
 While, the non-round materials are caught in the inner helix and are discharged
through a separate spout.
 rate of feeding is adjustable component.
 The feeding should be such that each grains/particle rolls independently for
effective separation.
 device is less versatile as compared to other mechanical cleaners, but it is simple,
inexpensive and quite useful for seed cleaning purposes.
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Prof. H. S. Chaudhari

8. Spiral Separator
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Prof. H. S. Chaudhari

9. SPECIFIC GRAVITY SEPARATOR
 separation according to different in density or specific
gravity of the materials.
 This separator works on two principles,
(1) the characteristics of grains to flow down over an
inclined surface,
(2) the floatation of the particle due to upward movement of
air.
 The main part of the device is a triangular-shaped
perforated deck.
 The deck is properly baffled underneath to ensure uniform
distribution of air over it.
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Prof. H. S. Chaudhari

10.  The pressure or terminal velocity of the air raising through the
deck is controllable very closely within a wide range.
 The mixture of grains is fed into feed box.
 The air is blown up through the porous deck surface and bed of
the grain by a fan at such a rate that the material is partially
lifted from contact with the deck surface.
 The lightest materials are lifted to the top of the stratified mass.
 The heavier particles are not lifted by the air. The stratified mass
moves along the direction of conveyance due to oscillating
motion of the deck and is discharged at the right edge of the
deck.
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Prof. H. S. Chaudhari

11. Specific Gravity Separator
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Prof. H. S. Chaudhari

12. INCLINED DRAPER
 The separation due to difference in shape and surface texture.
 The mixture to be separated is fed over the center of an inclined
draper moving in upward direction.
 The round and smooth grains roll or slide down with the draper
at faster rate than the upwards motion of the belt and these are
discharge in a hopper .
 The flat shape or rough surfaced particles are carried to the top
of inclined draper and dropped off into another hopper .
 The belts of different degrees of roughness may be used as
draper for separate materials. 12
Prof. H. S. Chaudhari

13. Seed hopper
Round or
Smooth
Seeds
Rough
Seeds
Canvas or
Rubber Draper
Inclined Draper
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Prof. H. S. Chaudhari

14. VELVET ROLL SEPARATOR
 The velvet roll separator or roll mill separates grains on
the basis of difference in the shape and surface texture.
 It is a finishing machine and should be used only after
cleaning and separation of grain from the chaff trash.
 It is effective in separation grain with rough seed coat or
sharp angles from smooth surface grain
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Prof. H. S. Chaudhari

15. Metallic
duct Velvet
Roll
Rough
Seeds
Rough and
Some smooth
Seeds
More
smooth and
Some
Rough
Seeds
Smooth
Seeds
Velvet Roll Separator
Section A-A 15
Prof. H. S. Chaudhari

16. MAGNETIC SEPARATOR
 The magnetic separator performs separation on the basis of surface
texture and Stickiness properties of the grains.
 Since the grains do to contain any free iron, Therefore, are not
attracted by the magnet.
 A selective pretreatment of mixing Finely ground iron powder to
feed mass is given.
 The grain mixture is fed to a screw conveyor or other mixing device
that tumbles and mixes the grain with a proportioned amount of
water.
 Due to moisture, iron powder adheres to rough, cracked, broken and
sticky seed coat.
 Moisture does not remain on smooth grains so no iron powder
adheres to smooth surfaced grains. separation by magnetic
separators.
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Prof. H. S. Chaudhari

17. Feed hopper
Water
spray
Iron powder mixing
Magnetic drum
Magnetic separator
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Prof. H. S. Chaudhari

18.  The grain mixture is fed onto the top of a horizontal
revolving magnetic drum,
 The smooth grains that are relatively free of powder
fall along the drum simply by gravity.
 The materials with iron powder are attracted by the
magnetic drum and stick to it and are removed by
rotary brush or break in the magnetic field.
 Most magnetic separators have two or three removing
magnetic drums operating In a series. 18
Prof. H. S. Chaudhari

19.  The grain mixture is passed over these magnetic drums
increased the efficiency of operation.
 The extent of difference in seed coats, amount of water mixed,
amount of iron powder and thoroughness of powder-water
mixing operation affect the degree of successful separation by
magnetic separators.
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Prof. H. S. Chaudhari

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Prof.H.S.Chaudhari