DELINTING OF COTTONSEED
BY USMAN GHANI KHATRI
Delinting of Cottonseed
 In developed countries, cottonseed subjected
to various processes to get maximum utilities of
seeds. Whereas in Pakistan 90% of cottonseed
directly crushed (with linter on seed) to obtain
oil and meal. Where 7 to 8% oil is extracted by
oil expellers and rest of khalli or meal is used
as animal feed.
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Those ginners who have oil expellers can use more
economical process by installing delinting units.
The demand of delinted cotton is growing as raw
material for Viscose especially pulp, where in
Pakistan it being wasted as mixed during crushing
process with Khalli – till decade and half before India
was using this process of crushing, since then India
is applying Modern Technology to achieve maximum
benefit of cottonseed.
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 The meal from expellers may further process through
solvent process, where Hexane is used as solvent which
is recovered at the end of process of recycle by desolventisation.
 Some traces of solvent still remains in meal or khalli, that
can be removed by toasting processing of meal, there
are many big feed manufacture who are willing to buy
this material for further processing meal to remove any
trace of solvent or Toxin like Gossypol and afflotoxin.
Solvent process gives additional 7 to 8% of oil then
conventional expellers, this process is more economical,
viable and profitable.
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 Since one decade China and India are working
continuously on cottonseed processing to get
maximum benefit of cottonseed.
 Following diagram shows various stages of process:-
COTTONSEED PROCESSING
 The Cottonseed consists mainly of inner kernel,
usually called 'meats'. This meaty portion contains all
the oil as well as proteins. The meat is enclosed in a
tough fibered shell called Hull. Over the hull stick out
the cotton fibred which escape the ginning and left
on seed These cotton fibers are called 'Lint'.
About Cottonseed And Its Products:
 Cotton, or Kapas as it is called, obtained from the field
contains about 65 to 70% cottonseed. The seed is separated
from the cotton in ginneries. An average analysis of
cottonseed obtained from long staple variety of cotton is as
follows:
a) Oil content: 19%
b) Protein content: 19%
c) Lint content: 11 %
d) Hull content: 36%
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 When the seed is delinted, it yields lint as a by-
product. The delinted seed is usually de-hulled
yielding meats and hulls. The hull is another byproduct. When the meats are crushed in expellers
one gets crude cottonseed oil and oilcan. The
oilcan, when subjected to solvent extraction, yields
further crude cottonseed oil, and deoiled cotton
meal rich in proteins.
Use of Cotton Products:
 Cottonseed oil when refined is edible. The deoiled
cottonseed is rich in protein content and extensively
used as a cattle feed. In Europe, it is used specially
and can be fed to the cattle in place of hay. The lint
obtained from cottonseed is used as raw material in
papermaking, artificial silk manufacture, ammunition
making (nitro cellulose) and upholstery.
Plant, Process and Machinery:
 Cottonseed is first cleaned free from the foreign matter such as
stones, shale, sticks, iron, earth etc. The foreign matter in the
seed can be anywhere between 2 -5% depending upon the way
Kapas is handled at the fields. It is essential to remove the
foreign matter so as to protect the further processing machinery
from damage and excessive wear and tear. Seed cleaning is
carried out over reciprocating type sieves to separate sticks,
shales, belhes, earth etc. The seed is then pneumatically lifted to
separate the heavy matter such as stones, iron, etc. The cleaned
seeds are then fed into a battery of delinting machines in which
tight rolls of seed are pressed over high-speed circular saws.
The saws scrape off the lint form the seed and the lint is sucked
pneumatically into lint beating and cleaning devices.
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 The lint beating and cleaning is done to increase the
cellulose content of the lint and the product is
bagged. Delinting is generally done in two stages, in
the first stage a light cut is taken and in the 2nd
stage more severe cut is allowed. The fiber length of
the first lint is much longer than the second cut lint.
Long fiber is preferred for the use in paper and
artificial silk industry, The recovery of lint varies from
seed to seed depending on its original lint content,
But generally the recovery is about 1.9% to 2.2%
first cut and 3.8% to 4.5% second cut.
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 The delinted seed is then fed into hullers wherein the
outer hull of the seed is cracked by knife-edge mounted
on high-speed rotors. The mixture of hulls and meats so
produced is passed over reciprocating sieves to separate
the meats from hulls. The hulls are passed through a
series of separators and beaters to ensure that they are
free of entrained oil and protein bearing meats and then
bagged, The meats containing about 35% oil and 35%
protein are conveyed to the expelling section (Oil Mill) for
crushing. Some portion of hulls is allowed to go with
meats for adjusting the protein content of the final meal
to the desired level.
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 In the Oil Mill the meats are cooked in a tempering
apparatus and fed into a series of expellers
consisting of heavy screws working in strong cages,
The meats arc squeezed with pressure as high as 5
to 10 tonnes per Sq. Inch. At this pressure the oil is
squeezed out through the slits in the cage and the
meats, pressed into oil cakes, containing about 7%
to 8% oil, are discharged through the cage,
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 The Crude oil obtained from the expellers is filtered through plate and
frame type filter presses and then sent to refinery, In the refinery the oil
is first neutralized with caustic soda, which reacts with free fatty acid
content of the oil and forms soap, The soap is separated from the oil by
means of centrifuges or by settling and is called soap stock. The
treatment with caustic soda also removes the gums, dark coloring
matter and pigments from the crude oil. The oil is then washed with hot
water to free it from soap and caustic soda, The washed oil is dried in a
flash drier and is sold as washed cottonseed oil.
 To convert into cooking edible oil, the washed oil is first bleached with
activated earth and carbon and then deodorized under high vacuum
and temperature with open steam.
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 The oil cake received from the Oil Mill is conveyed to the
preparatory section of the solvent extraction plant. To get best
extraction results the oilcake is broken into 3 to 4 mm pieces with
minimum 'fines', in cake sizing and cracking machines, The cake so
prepared is fed into extractor where it is treated with low boiling
petroleum solvent called normal hexane. The hexane dissolves the
oil from the cake forming a solution and the oil content of cake is
reduced to below 0.7%, The solution of oil in hexane is distilled in
specially designed distillation equipment under vacuum, to
evaporate the solvent from the oil. The oil thus separated is sent to
the refinery and handled the same way as the expeller oil. The
deoiled cake from the extractor containing absorbed solvent is
heated to about 100 Degree Celsius in tubular jacketed driers with
steam to evaporate the solvent or in specially designed
desolventiser toaster.
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 The desolventised material is cooled, humidified in a
humidifier and bagged. The solvent vapors issuing
from the desolventiser as well as from the distillation
are condensed in series of condensers and
recovered. The solvent thus recovered is used for
further extraction.
 The process flow with the material balance is shown
in Appendix attached herewith. As seen from the flow
chart and above description of the process, the
machinery required for processing cottonseed can
be classified as follows:
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a) Cottonseed pre-processing plant consisting of seed
cleaning, delinting, and decorticating machinery to produce
cottonseed meats, lint and hulls.
b) Oil Mill for crushing cottonseed meats to produce
cottonseed oil and oilcake.
c) Solvent Extraction Plant to extract oil from cottonseed
oilcake to produce crude extracted cottonseed oil and deoiled
cottonseed meal.
d) Refining plant to refine both expeller and extracted crude
cottonseed oil and produce washed cottonseed oil and/or
edible cooking oil.
e) The auxiliary equipment to provide utilities to the project
such a steam, power, water etc.
THANKING YOU