| Why
Grain
is cleaned for
- human or animal feeding,
- improved storage,
-
seed use,
- further processing.
It is an operation related to quality and safety.
How
Cleaning
machines use differences in density, size
and shape to remove impurities from good grain.
Air
separates light impurities and the perforations of screens let small impurities
pass through or retain larger, oversize material.
It is thus possible to remove
- inert materials (dust, stones, earth, straw, leaves, vegetable
impurities),
- weed seeds (wild oats, cleavers, sorrel, grass
seed, etc..),
- seeds of other crops,
- damaged
or poor grains, shrunken or very light seeds (unsuitable for germination or food
requirements) When
Different settings and
different machines are used for grain cleaning depending on the requirement:
Intake:
Precleaning allows safe storage of a more homogeneous
crop. Throughput is generally at a maximum and may also be variable.
Preparation
for further processing: A fine cleaning, grading
or processing improves quality and value or raise to seed standards. Throughput
should be even and may be reduced for improved quality.
Outloading:
Cleaning must be fast enough and at an even throughput. i.e.
Impurities
cause uneven drying or aeration and prevent safe storage.
One always tries
to "separate the tares from the wheat" before sowing.
Small or broken
kernels must be removed from seed, but broken grains are preferable to stones
in lentils for example.
Sunflower seed in malting barley spoils the foam on
beer. |
| |
