According to the impurities size, there are large ,small ,long and short
impurities; according to the weight, there are light and heavy impurities.
Even if it is light, there are still light weight, density (specific gravity) and
light weight. There are differences in color, which is called heterochromatic
particles, and is also a kind of classification of seed impurities.
The nature of the impurities is different, and the method of cleaning is
different. Different cleaning methods necessarily require different principles
of machinery, which determines the diversity of seed processing machinery.
Buying machinery, to be practical, first figure out what the main impurity