Priciples of Milling Diagram
Priciples of Milling Diagram
Priciples of Milling Diagram
Starch : (endosperm)
80% 20%
Quality of kernel from center to skin :
Ash(mineral):
endosperm: 0.3% - 0.4% bran : 2% - 4% germ 4.5% - 5 % aleurone 6% - 8%
Color:
Protein:
Gluten quality:
Wheat variety :
Endosperm contains of lipoprotein layer with starch granules
Mill flow chart ( diagram ) : a chart which shows the way of stock during the milling
process and the relations between stock & machines which is passed through
parts of a diagram :
Break rolls
Grading
Middling
2 – Reduction Scratch
Collecting
passage : A diagram contains different passages – a passage is a special path for a special
quality of stock which is passed through special machines for a special process – each passage
starts from the beginning of a roller mill to the end of a plansifter with all of the intermediate
machines and process
- Break: open up the wheat kernel and scraping the endosperm from the skin
- Reduction: reducing the size of endosperm produced in break system (in shape of
semolina) to reach to the flour size
- Purification: purify the semolina produced in break and send the clean semolina to
reduction system
quality of stock in each part of diagram
Fine flour
More extraction
Results Clean and white flour
Low ash
Control of starch damage
Purifier
Detacher
information should be shown in diagram :
Rules of diagram
B (1-5) break
f fine
c course
C(1-12) reduction
a clean semolina
b composite semolina
Br bran finisher
FD flour duster
DBr bran finishing sifter
Brg bran grinding – bran finishing roller
P purifier
Div grading
Large particle size must be equal or less than twice of small particles
particle size will be as shown : scalper > semolina > middling > dunst > flour
Point : dressing means taking out the flour from the stock
As it is shown above we miller must add any microns to the sieve size to have better and
narrow range as ash and sizing for semolina
Point : semolina which is sent to purifiers must be in a narrow and same range of ash content
and size to have a better purification
Hard wheat :
More hardness in wheat means more semolina production then miller should reach to a nearer
range of size and ash content than semi hard wheat and should add more microns to sieve size
Typical flow chart : as it is mentioned in wheat specification in chapter 1 and the kind of
grinding the different kind of wheat in chapter 4 now we know that flow chart as different kind of
wheat s are different to each other . some of the typical flow charts are as follow :
Point : semi hard wheat is used un Iran then all the diagram set up will be adjusted as used in Iran
Quality grades :
There are 4 different quality grades in a flow chart which is shown by different colors as
following diagram
Quality grades are very important and a miller should know them as well to avoiding some
mixing or turning back in quality grades and following the instruction of quality when
sending any stock from break to reduction or from reduction to other parts of diagram
Set up of B1 :
Function of B1 is shearing and opening up the wheat then a large range of quality and sizes
will be produced . each stock must be sent to its own passage as quality and size fore more
process as follow :
B2: scalpers which are big particles of wheat must go to the next stage of break system
P1: course semolina is always dark and composite then must be sent to the first purifier to be
Cleaned
P2: fine semolina must be sent to the next purifier as their difference of size for cleaning
P3: middling is almost clean but for more insurance and quality production for white flour it
will send to the 3rd purifier for cleaning
C3: dunst and fine middling are always clean and will be sent to their first stage of reduction in
the same quality grade of B1 base on their size
F: flour will be produced in each stage and miller must get rid of flour in every stage as soon
as possible
Set up of B2 :
As the quality flow chart shows ‘ B1 & B2 are in the same quality grade . B2 is nearly the
same of B1 and the quality of stocks are the same then miller can set up the same sieve in
the sifter and send the stock to the same target .
the difference between B1 and B2 is in the first row of sieve . because the stock ( scalpers )
which are coming from B1 are in smaller size then miller can choose a little smaller sieve
size to have more
efficiency in sifting and grading
Introducing the grading system (Div) :
Plansifters have any limited in sifting area or No. of sieves for grading the stock as shown
in B1 and B2 .
if miller set the sieves as shown in above diagram then limitation in capacity will be
occurred and if miller needs the proper capacity then lost of fraction and quality will be
happened
diverting a part of stock to a different sifter for grading is the solution for holding the
proper capacity and different fraction with each other
Div . passage is extension of break sifter and a part of break system by name of grading
Which is mentioned as follow :
As mentioned before B1 and B2 are the same passages in a same quality grade then they
can send their stock to a same extension or to different Div system according to the diagram
then :
According to the mill capacity Div. can be a complete or half compartment of a sifter
Set up of a Purifier :
Purifier is a kind of machine for cleaning and purifying the composite semolina with the
action of both sieve and aspiration and its function is based on quality
each sieve cover should have the proper size to separate semolina and bran as well as
possible
as a purifier separates the stock as quality ( size & density together) then miller must be
familiar to the density of different stock as it mentioned bellow
fluidfication and stratification will occur at the beginning of each purifier by air current.
Small and dense semolina which are clean and pure will touch the sieve cover and
become separated by sifting but large and composite semolina and other light particles
will stay over the sieve by air current.
Large and light particles will lead out from the machine as over tail and small particles
which are pure semolina will passed through sieves .
Germ :
How to extract:
- C4 passage must have smooth rollers for flaking the germ and increasing the size
- 1250 micron sieve cover can separate the flaked germ
Sifting area :
0.055 square m / 100 kg / 24 hr
Sifting area should be find by the information of plansifters according to the capacity of mill
Break release :
Exmple 1 : 120ton/24hr
11.6mm/100kg/25hr
11.6 100
X 120000 (120000*11.6)/100 = 13920 mm = 14000 mm
7 roller mill 1000*250
Break roller Break sifter Reduction roller Reduction sifter
B1one pair 1 section C1a one pair 1 section
B2one pair 1 section C1b one pair 1 section
B3one pair 1 section C2 one pair 1 section
B4one pair coarse 1 section C3 one pair 1 section
one pair coarse
B5 one pair 1 section C4 one pair 1 section
Div ½ section C5 one pair ½ section
C6 one pair ½ section
C7 one pair ½ section
0.055 100
X 120000 (0.5*120000)/100 = 66 sq m
Exmple 2 : 250ton/24hr
9.6/100kg/25hr
9.6 100
X 250000 (250000*9.6)/100 = 24000 mm
12 roller mill 1000*250
Break roller Break sifter Reduction roller Reduction sifter
B1two pair 2 section C1a two pair 1 section
B2two pair 2 section C1b one pair 1 section
B3two pair 2 section C2a two pair 1 section
B4one pair coarse 2 section C2b one pair 1 section
one pair coarse
B5 one pair 1 section C3 one pair 1 section
Brg one pair 1 section C4 one pair 1 section
Div1 1 section C5 one pair 1 section
Div2 1 section C6 one pair 1 section
C7 one pair 1 section
C8 one pair 1 section
C9 one pair 1 section
C10 one pair 1 section
0.055 100
X 250000 (0.5*250000)/100 = 137.5 sq m
Finish