A detailed description of different types of cleaners used in grain processing and evaluation of their performance

1. PRESENTED BY:
ARSHPREET KAUR
B.TECH.
(AGRI. ENGG. AND TECH.)

2. CLEANING
1. Scalper
2. De awner
3. Fanning mill
4. Air screen cleaner
5. Specific Gravity separator
6. Indented cylinder separator
7. Cyclone Separator
8. Pneumatic separator
9. Inclined draper
10. Electrostatic separator
11. Magnetic separator

3. Scalper
 A scalper can be used to rough
clean seed when trash content is
high.
 The scalper basically consists of a
vibrating or rotating screen or
sieve.
 The screen perforations are large
enough to allow the rough seed
to pass through readily while
large inert material is scalped off
and removed from the seed lot.
 Some of the high moisture
particles may be removed
 Normally much higher output
than fine cleaning

4. De awner
 Before air screen cleaner
 Optional, it can be bypassed
 Seed flows much better in rest of
cleaning process
 Important when mechanical
planting machines are used
 May be important for breaking
dormancy in some species

5. Fanning Mill
 Screen cleaners that employ an air blast
to assist in cleaning is known as fanning
mill. Though
 these are used for cleaning but these are
not effective as regards to density and if
the materials have the
 same or nearly the same shape. Here in
addition to the aspirating fan used to
draw air through the
 material fed on 1st screen unit, another
fan is used to force the air through the
product after fine grading

6. AIR SCREEN CLEANER
 A common air screen cleaner for processing seed uses two air blasts and two screens.
 The first air system removes dust and light chaff before the seed reaches the first
screen.
 The first screen allows the good seed to drop onto the second screen. The large
foreign material rides over the first screen and is discarded.
 The second screen is a grading screen
 Uses three cleaning systems; aspiration, scalping screen and grading lower screen
 Classified into two types based on the movement of the screening surface
• Vibratory screen cleaner
• Rotary screen cleaner

7. Vibratory screen cleaner
 Screening unit is composed of double or multiple
screens.
 Screens are tightened together and suspended in such
a manner that these have horizontal oscillating and
slightly vertical motion.
 The slope of the screen is adjustable to control the
rate of forward travel of the grain
 To avoid clogging, the screens are fitted with brush
Two screen m/c fitted with aspirator to suck the
lighter materials
 Coarse impurities are screened off by upper screen
Fine impurities are screened off by lower screen
Grains are again cleaned by upward draft of air in the
ascending separator
 During this process, remaining lighter impurities and
shriveled grains are sucked away
 Lighter impurities are removed by Cyclone separator

8. Rotary air screen cleaner
 Has normally circular decks
 Motion is circular in horizontal plane
 Either single or double drum
 Consists of a rotary screen, aspirator and
hopper
 Sound grains pass through the screen
perforation into the center of the screen
drum. Oversized material is retained above
and pass out through an outlet.
 Sound grains come out at the center side of
the drum rotating at low speed and fall onto
the vibratory screen which remove the dirt
particles
 Light impurities are sucked away by the
aspirator
 Cleaned grains are discharged through the
discharge chute

10. Specific Gravity Separator

13. Cyclone Separator
 The cyclone separator is used extensively in
processing and other operations as a device
for collecting end product.
 It is also frequently used in connection with
pneumatic conveying of products
 and wastes from processing. These are used
for removal of particle about 10 μm or more
in diameter from the air stream.
 These are used for separating particle from
liquid droplets from gases.
 Cyclones are basically used for cleaning air
or for settling the dust particles etc.
 It is used in combination with some other
machines e.g. as you have seen with
hammer mill/aspirating column etc.

15. Pneumatic Separator
 The aspirating column is the equipment
which is used for this purpose.
 The material is fed from the duct provided at
the side.
 The lighter particles have less terminal
velocity whereas grains and other heavy
particles have more value of terminal
velocity.
 This difference in terminal velocity provides
the basis for the separation of materials.
 This is best suited for removing very small
sized and immature grains from healthy
grains.

19. Inclined Draper
 The separations by inclined belts draper takes place
due to difference in shape and surface texture of the
material.
 This technique of separation is used when all other
methods fail.
 The mixture to be separated is fed over the centre of
an inclined draper belt moving direction.
 The round and smooth grains roll or slide down the
draper at faster rate than the upward motion of the
belt and these are discharged in a hopper.
 The flat shape or rough surface particles are carried to
the top of the inclined draper and dropped off into
another hopper.
 The belts of different degrees of roughness may be
used as a draper for separate materials.
 Feed rate, speed of draper and angle of inclination
are other factors for effective separation of dissimilar
materials.

20. Electrostatic Separator
 Electrostatic beneficiation allows for separations based
on differences in surface chemistry (work function) or
dielectric properties.
 In some instances, these separations would not be
possible using size or density separations alone.
 Electrostatic separation systems operate on similar
principles. All electrostatic separation systems contain
a system to electrically charge the particles, an
externally generated electric field for the separation to
occur in, and a method of conveying particles into and
out the separation device.
 In all electrostatic units, high potentials are used to
give practical forces of attraction. Since
 electrostatic charges leak away rapidly in moist air, so
equipment & air must be dry.

21. Magnetic Separator
 Magnetic Separators are most commonly used to
separate iron or steel materials that have a low
magnetic attractivity.
 Since magnetic separators have a wide variety of
functions, several devices are available.
 A simple method is of keeping a magnet close to the
contaminated material as it passes along a conveyor.
 The iron and steel particles are collected on the face
of magnet and removed periodically.
 Another method is using a magnetic pulley in a belt
conveyor. The magnet will attract the iron or steel
particles and therefore deflected to one side
 Magnetic separator performs separations on the basis
of surface texture and stickiness properties of the
grains.
 Since the grains does not contain any free iron,
therefore are not attached by the magnet.