3. OIL EXPELLERS
• Used to extract oil from oil seeds
• Done by
1. traditional animal drawn ghanies
2. mechanical expellers /screw press
3. solvent extraction units etc…
4. GHANI EXTRACTION
• Consist of a wooden mortar and a pestle
• Mortar fixed to the ground and pestle to the
animal
• Animal is rotated in the mortar
• Seed get crushed by the generated friction
/pressure
• Oil moves out through an opening at the bottom
• Cake is scooped out from the top in the mortar
5.
6. SCREW PRESS
• Consist of horizontal shaft , the screw
assembly is formed integrally with this shaft
• Screw rotates with in a cage or barrel
• Configuration of screw is such that the volume
displacement at the feed end is considerably
greater than at the discharge end
• Movable choke in the discharge end controls
the operating pressure
7. MINI OIL EXPELLER/SCREW
OIL PRESS WORKING
PRINCIPLE
1.When oil press is on work, material enters the extruding chamber from the
hopper and then moves forwards by the rotating pressing screw and is
pressed.
2.Under high temperature condition in the chamber, there is quite strong
friction among press screw, chamber and the oil materials.
3.On the other hand, root diameter of the pressing screw carries larger from
one end to the other.
4.Hence when rotating, the thread not only pushes particles moving forwards
but also turns them outwards as well.
5.Meanwhile, particles adjacent the screw will rotate along with screw’s
rotating, causing every particle inside the chamber to possess different speed.
6.Therefore, relative movement among particles creates neat which is
necessary during manufacturing because of helping protein change property,
damage colloid, increase plasticity, decrease oil’s elasticity, resulting in high
oil.
8. SOLVENT EXTRACTION
• separation of a substance from a mixture by preferentially dissolving that
substance in a suitable solvent.
• Solvent extraction is achieved through the grinding of seed.
• The ground seed or cake is then purged or washed with a petroleum
distillate (the most common chemical used is hexane) which releases the
oil in the seed.
• The solvent is then “flashed off” by heating the oil in a sealed chamber
• The oil/solvent blend is next heated to 212º F (100º C) to distill off the
solvent.
• This process theoretically leaves virtually no detectable levels of solvent
in the oil if the proper techniques have been applied. However,
microscopic portions (up to 25 parts per million) of hexane can remain in
the meal and the finished oil. Commercial oil companies claim hexane is
completely removed in the recovery phase of the extraction cycle.
However, this cannot be guaranteed as manufacturing practices and
quality control standards vary enormously from processor to processor.
