Conventional rice mills are
introduced in this section. In the 1920s,
Taiwan
introduced mechanical rice mills but they did not become prevalent
till the power system was completed. Most of these early period
mechanical rice mills had wooden casings and belt conveyors that
transmitted motor power.
External appearances of rice mills varied as to location and
installation technician. However, the differences are negligible.
Although a rice mill looks as if it is one unit, in actual,
dehusking/dehulling and rice refining processes were separate
operations. Therefore, a rice mill has two Material unloading
opening and two Material discharge opening.
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Asphalt coating helps
block moisture |
Grains should not be in direct
contact with ground surface |
◆《Storehouse storage
before rice milling》
Generally speaking, farmers or operators preserve rice grains in dry
form. This is because rough rice/paddy is less likely to become
moldy. Once milled into brown rice or milled rice/polished rice,
protection from hull is no longer available, which results to
greater mold formation. Milling factory operators generally build
storehouses to store rough rice/paddy. In order to avoid rough
rice/paddy dampening, mold formation or germinating, anti-moisture
handling is first done inside storehouses such as coating asphalt on
walls to avoid moist from penetrating, and placing plywood on ground
surface before placing rough rice/paddy so as to avoid direct
contact with ground surface. [Ground surface has higher moist
content] In addition, well ventilated storehouses also reduce
humidity and heat which in turn ensure rough rice/paddy quality.
◆《First step of rice milling -dehusking/dehulling-remove
hull to obtain brown rice》
As mentioned earlier, milled rice is subject to mold formation,
thus, rice milling factories often estimate their delivery Qty to
determine the amount of rice milling. During early periods, milled
rice is mostly packed into large packages. Nowadays, people tend to
eat less than before so rice usually comes in small packages.
Rough rice/paddy undergoing milling is first sieved to remove
impurities such as sand, stones, cement, metal, and plastic using a
destoner/stone picker. Then, it undergoes dehusking and dehulling.
Rough rice/paddy is then dumped at Material feeder. Using an
elevator, it is taken upwards through a precleaner where small
pebbles and weeds are sieved. The hull sieved by a dehusker/dehuller
then passes through several distributors and wind machines to
separate brown rice and hull. Hull is blown by the wind machine to
the chaff room at the back of the mainframe room for stacking. Brown
rice then exits from the Material discharge opening. It is
subsequently placed in a sack or plastic bag to weigh. During the
grain ridging process, operators may observe the dehusking/dehulling
progress in the distributors. If there is too much impurities in the
brown rice, return to the distributor and wind machine through the
switch valve to engage in separation once, twice, or three times
until satisfaction is reached. If brown ice is desired, pack only
after dehusking/dehulling. There is usually scales at the lower end
of the Discharge opening for direct weighing.
◆《Second step of rice milling -rice refining-Bran layer and germinal
layer are removed to attain milled rice/polished rice》
After rice dehusking/dehulling, it becomes brown rice which is ready
to be cooked and served. However, though brown rice is more
nutritious, it is less tasty. Most people are still accustomed to
milled rice/polished rice. In order to change brown rice into milled
rice/polished rice; “rice refining” is necessary. As said earlier,
although the rice mill is one machine unit, dehusking/dehulling is
separated from rice refining. Therefore, after brown rice is
attained, it is refined by pouring brown rice into rice refining
material unloading opening. Then, it is carried upwards to the
bucket elevator for temporary storage. It subsequently enters a rice
refining machine where fine bran is picked from brown rice.
Meanwhile, milled rice/polished rice emerges. However, removed fine
bran is still mixed in it so it has to be sent to the rice bran
separator to remove most of the fine bran. Then, a fine bran wind
machine is used to blow off minutes particles.
Most certainly, like dehusking/dehulling, rice refining is not
completed in one single setting. Repeated refining is required to
obtain milled rice/polished rice. At times rice milling factories
add lime powder during the rice refining process to make rice appear
whiter. Therefore, some rice mills have “lime powder adders”
installed for easy lime powder adding.
Normally, rice refining has to be performed 6-7 times to completely
remove fine bran. If rice appears white, the valve opens for rice to
be released from the rice refining area exit. It is then ready for
packing. There are scales at the lower end of the material unloading
opening for direct rice weighing upon release.
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Rice refining adjustment barrel
and rice refining machine |
Fine bran remover |
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Lime powder adder〔Rice
mill at
Science and
Technology Museum〕 |
Scales are placed at the lower end
of the milled rice/polished rice
Material unloading opening for
operation purpose |
◆《Conventional rice milling factories struggling for survival》
Setting
up a rice milling factory requires capital funds, and lands.
Therefore, rice milling factories were mostly established by wealthy
people in the locality. Early rice milling factories not only
outsourced rice milling, they also purchased rough rice/paddy from
peasants and re-sold some of them to rice stores in the city after
processing. They would leave a small portion of it to sell by
themselves. One-line rice milling was developed as times changed.
The state-of-the-art computerized equipments were more competent
than conventional wooden rice mills. In addition, more and more
farming houses purchased family type rice mills to perform milling
themselves. This resulted to fewer outsourcing opportunities. Some
small rice milling factories even stopped rice milling machine
operation altogether and purchased packaged rice from large rice
factories instead. They either became vendors or in some cases, were
compelled to close down business. In a few years time, all these
conventional rice milling factories are likely to disappear
completely.
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