RICE MILLING

process of converting paddy into rice

milling

cleaning

hulling

paddy separation

bran removal

polishing

grading

weighing

bagging

basic milling processes

removing foreign materials e.g. rice straws, stones, seeds, etc. from the paddy

cleaning

removal of husk from paddy with minimum damage to the grain

dehusking or hulling

separating dehusked paddy from remaining grains

most dehuskers remove 90% of the husk

paddy separation

removing the bran layer from the grainto produce polished rice

bran removal

separating broken grains from ubroken

grading

• 70%

• carbs

• some proteins

• vit B

rice kernel

• 20%

• inedible part

• industrial uses

hull

• 8 to 9%

• fiber rich

• vit

• minerals

• antioxidants

rice bran

1-2%

phytochemicals

proteins

vit

rice germ

small capacity single machine

large capacity multiple machine

2 general types of mill

village level for custom milling

steel huller, single pass rubber roll rice mill

capacity: 45-270 kg/hr

small-capacity single machine

commercial milling

2-4 tons/hr

consists several stages of milling

equipment are used to move byproduct into various machines

large-capacity multiple machine

steel hullers

rubber roll paddy huskers

under-runner disc sheller

dehusking equipment

works via friction between grains and steel parts to scrape off husk and bran

higher power req, lower paddy recovery

800-900 rpm for small mills

600-800 rpm for larger mills

steel hullers

consists of two rubber rolls rotating at diff direction, one is slower

one roll moves 25% slower

high milling recovery

rolls wear out (100-200 tons per pair)

rubber roll paddy huskers

uses two horizontal iron disc with abrasive coating, bottom disc rotates while top is fixed

centeifugal force moves outward, and friction dehusks it

under-runner disc sheller

bran removal and finishing