rice milling

Describes the traditional and modern methods of milling of paddy /rice

1. Rice Milling
Traditional rice milling Modern rice milling

2. Traditional rice milling Traditional rice milling
machinerymachinery
Hand pounding equipmentsHand pounding equipments
Single huller and battery of hullersSingle huller and battery of hullers
Sheller cum hullerSheller cum huller
Sheller millsSheller mills

3. SINGLE HULLER

4. Milling refers to size
reduction & separation
operations used for
processing of food grains
into edible form by removing
and separating the inedible
and undesirable portions

5. Cleaning/ SeparationCleaning/ Separation
Husking Husking
Sorting Sorting
Hydrothermal treatment (Paddy)Hydrothermal treatment (Paddy)
Whitening Whitening
Polishing Polishing
GrindingGrinding
Sifting Sifting
MODERN RICE MILLS

6. Cleaning
 Width and thickness of the grain
 Length of the grain
 Aerodynamic properties
 Specific gravity/ Coeff. Of friction
(destoners)
 Colour
 Ferromagnetic properties
 Electrical properties

7. CLEANINGCLEANING
Open Double-sieve Open Double-sieve
Pre-cleanerPre-cleaner
Price is lowPrice is low
Can be manufactured Can be manufactured
locallylocally
Bottom sieves-clogged Bottom sieves-clogged
Lower separation Lower separation
efficiencyefficiency
Single Scalper Drum Single Scalper Drum
cleanercleaner
Easy to operate Easy to operate
&maintain&maintain
Sieve cleaning device Sieve cleaning device
prevents cloggingprevents clogging

9. Stoner with aspiratorStoner with aspirator
Remove dust and stone from paddy Remove dust and stone from paddy
effectivelyeffectively
Paddy CleanerPaddy Cleaner
Closed type double action aspirator Closed type double action aspirator
precleaner (West German)precleaner (West German)

10. STONER WITH ASPIRATOR

12. HUSKINGHUSKING
Purpose: Remove husk from paddy Purpose: Remove husk from paddy
without damage to the bran layer and without damage to the bran layer and
rice kernel.rice kernel.
Husking machine names: Huskers, Husking machine names: Huskers,
dehuskers, shellers and hullers dehuskers, shellers and hullers

14. Husking
 Compression and shear
(Rubber roll sheller)
 Abrasion and friction (emery)
 Impact and friction (Centrifugal
type paddy sheller)

20. Impact type paddy huskerImpact type paddy husker

Price is reasonably lowPrice is reasonably low
Operating cost is low due Operating cost is low due
to small power to small power
requirement (1HP/500kg requirement (1HP/500kg
paddy/hr).paddy/hr).
Machine is compact and Machine is compact and
portableportable
Breakage %age Breakage %age
increases with the increases with the
increase of husking ratio increase of husking ratio
Rubber roll huskerRubber roll husker
Highest %age of sound Highest %age of sound
and whole husked rice is and whole husked rice is
produced as the risk of produced as the risk of
breaking the kernel is breaking the kernel is
small and the chance of small and the chance of
forming scratches on the forming scratches on the
kernel is also nil.kernel is also nil.
Operating costs are high Operating costs are high
due to wear of rubber due to wear of rubber
rolls. rolls.

25. GRINDING

26. SeparationSeparation
Husked rice is separated from the Husked rice is separated from the
mixture of paddy and husked rice by the mixture of paddy and husked rice by the
paddy separator.paddy separator.

28. Paddy separator Paddy separator
(Japan)(Japan)
Consists of number of identical inclined Consists of number of identical inclined
trays with dimples over the surfacetrays with dimples over the surface
Separating condition of the mixture on Separating condition of the mixture on
the dimpled tray is always visible & can the dimpled tray is always visible & can
be adjusted accordinglybe adjusted accordingly
Operation is simple, power requirement Operation is simple, power requirement
is also smallis also small
Disadv: It is difficult to manufacture the Disadv: It is difficult to manufacture the
dimpled trays locally.dimpled trays locally.

31. Whitening Whitening
Refers to the operation of removal of Refers to the operation of removal of
germ, pericarp, tegmen and aleurone germ, pericarp, tegmen and aleurone
layers from husked rice kernels.layers from husked rice kernels.
Also called: Polishing or Pearling or Also called: Polishing or Pearling or
ScouringScouring

32. 3 major whitening 3 major whitening
machines: machines:
Vertical abrasive whitening cone.Vertical abrasive whitening cone.
Horizontal abrasive whitening roll.Horizontal abrasive whitening roll.
Horizontal metallic friction type roll.Horizontal metallic friction type roll.

33. Vertical abrasive whitening cone or Vertical abrasive whitening cone or
Pearling conePearling cone
AdvantagesAdvantages
It can deal with any It can deal with any
variety of rice. Its variety of rice. Its
performance is performance is
excellent with excellent with
parboiled riceparboiled rice
Degree of whitening Degree of whitening
is adjustableis adjustable
Life of the machine is Life of the machine is
very longvery long
Operational cost lowOperational cost low
DisadvantagesDisadvantages
Machine is big and Machine is big and
heavyheavy
Requires skilled Requires skilled
operators & attention.operators & attention.
Power requirement is Power requirement is
highhigh
Pressure distribution Pressure distribution
along the vertical line along the vertical line
is not uniformis not uniform

35. Horizontal abrasive type Horizontal abrasive type
whitening machinewhitening machine
Machine consists of an abrasive roll fitted Machine consists of an abrasive roll fitted
with steel screw & cap cover clamped on a with steel screw & cap cover clamped on a
horizontal hollow shaft rotating @ horizontal hollow shaft rotating @
1000rpm in a slotted cylinder. 1000rpm in a slotted cylinder.
AdvantagesAdvantages
Total & head yields are high.Total & head yields are high.
Bran removal is easier & uniform due to jet Bran removal is easier & uniform due to jet
air systemair system
DisadvantageDisadvantage: needs careful attention.: needs careful attention.

39. Friction type whitening Friction type whitening
machinemachine
Purpose: to remove remaining bran easily Purpose: to remove remaining bran easily
& uniformly from partially whitened rice & uniformly from partially whitened rice
produced by the horizontal abrasive produced by the horizontal abrasive
whiteners.whiteners.
Production of uniformly whitened rice with Production of uniformly whitened rice with
shining appearance is the main feature of shining appearance is the main feature of
this machine.this machine.
Broken %age may be increased if the Broken %age may be increased if the
machine is not operated properly.machine is not operated properly.

43. Thank
you