Assignment of Seed Processing on Gravity Separator and Color Sorter

Topics: Seed, Density, Ultraviolet Pages: 12 (4249 words) Published: November 7, 2012

Submitted to Dr. Yadvika

Submitted by Aman Dhillon 2009AE05BIV

Color Sorter
Separation Principle
Electronic color sorters separate seed by differences in color. Each seed is viewed and electronically compared with a pre-selected color background, and accepted or rejected. The color sorter can also separate off-color mud balls, other seed kinds and discolored or other-variety crop seed whose color is different from that of the good seed.

The first commercial color sorter was manufactured in 1931 by ESM (Electric Sorting Machine) in Lowell, Michigan, to sort Michigan Pea Beans (now called Navy beans). Since that time, sorters have been adapted to sort/separate many different products, including seed, fresh and cooked food products, snack items, minerals, plastics, etc. Basically, any dry particulate solid that requires visual inspection and can be accelerated to a common speed and singulated (i.e., placed in a row so they can be viewed one by one), is a good candidate for color sorting. Many large crop seed such as peas and beans differ in color between varieties, and can be separated efficiently by the color sorter. Traditionally, small seed have not been sorted due to low capacity, but today's multiple-channel machines with advanced electronics make small-seed sorting amiable option. Color variation may also occur due to immaturity or disease, which makes it possible to remove affected seed. Some diseased bean seed carry pathogens, which fluoresce under ultraviolet light; with a UV light source in the color sorter, diseased seed can be removed. Rice processing plants also use color sorters as a final cleaner for polished rice, to remove red rice, stones and other off-color particles. Many food processing plants also use color sorters.

Place in Conditioning
Color sorters are used in various locations in a seed conditioning facility, but are generally placed after the standard mechanical cleaning/sizing processes, and are used as a final inspection before bagging. Each application is different and technology continues to evolve, so there may be applications where the sorter can replace standard equipment, but for the most part, they complement standard cleaning machines. In corn and soybean conditioning, the sorter is usually placed before the gravity, as this provides the largest seed savings and highest-quality final seed lot. There are occasions where the sorter can be installed to sort the middling culls from the gravity, which increases yield of good seed and eliminates the need to re-run the middlings.

Regardless of its position in the cleaning sequence, the sorter enables the plant to run other equipment more efficiently, increase final seed quality, and generally increase out-turn of good crop seed. Sometimes, the polisher is installed just before the color sorter, to polish the seed and remove dust and other minor surface discolorations which could interfere with the color separation.

Operating Process
The color sorter accentuates the color (tone or shade) difference between acceptable seed and unwanted seed/particles, and then automatically removes unwanted seed from a continuously-flowing stream of the un-separated seed lot. The electronic color sorter views each seed individually, on one or two sides, by using various sensing devices. Each seed is compared with a pre-set selected background or color range, and is discharged from the machine according to its color. If it is of the desired color, the seed is discharged out the good seed spout. If its color or shade or spots on the seed falls within the reject range, a blast of compressed air deflects the seed and sends it into the reject discharge spout. By utilizing a spectrophotometer, a specific light wavelength or wavelengths can be selected, which will create the largest differential between good and unwanted seed. After this wavelength is determined, an optical...
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