London, United Kingdom
September 26, 2003
Enormous progress has been made in
the field of color sorters over the past few years. It has been
made possible by the further development of the electronics and
the continuous improvement of the optical detection systems. In
rice mills, color sorters have been applied for some time now to
remove dark or discolored rice kernels from white rice, and this
with very high efficiency.
“Processed by SORTEX” stands on many a rice bag. In traditional
rice-growing countries, this is the highest quality certificate
for high-grade rice. Now this technology is also being applied
to wheat, rye, and oats in combination with traditional cleaning
equipment. The Z-Series color sorters from SORTEX detect ergot,
dark contaminants, germ discolorations, dark pebbles, and
discolored and unripe kernels.
Quality starts with cleaning
Modern cleaning flow charts are increasingly using
new-generation color sorters. The reason: the potential presence
of health-impairing impurities such as ergot in rye. In durum
wheat cleaning, color sorters remove especially the discolored
kernels. Semolina made from this sorted wheat has a brighter
color and fewer specks. This improves the appearance of pasta
made from it. In sorting hulled oats, the dark kernels are
separated from the bright ones. The bright kernels are processed
into oat flakes for human consumption, and the dark ones into,
say, horse feed.
Detection of minute discolorations
The Z-Series color sorters are capable of processing up to 14
metric tons of durum wheat an hour, depending on the machine
size. SORTEX color sorters are equipped with high-performance
cameras to detect minute dots or color deviations of 0.3
millimeters and smaller. The high-speed ejection nozzles at the
machine outlet open as many as 300 times a second. Product
tracking and automatic calibration produce a consistently high
sorting accuracy and material throughput.
Successful application in the field
Development of color sorters started over 50 years ago. Since
then, more than 20,000 machines have been shipped. SORTEX color
sorters are in service around the world in numerous grain mills.
Their separating efficiency has been continuously improved and
has reached a very high standard today, thanks to the
application of new electronics and state-of-the-art cameras.
Buhler is a global Technology Group and a system partner for
the supply of plant, equipment, and process know-how in the
fields of Food Processing, Chemical Engineering, and Die
Casting, with some 6,200 employees worldwide. |
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This is how a color sorter
works: The grain is fed from an
inlet hopper through a vibrating
channel and a chute to the
sorting system. The force of
gravity and the speed of fall of
the kernels lines up the
individual kernels before they
pass through the testing zone.
Two high-resolution cameras per
chute, coupled with the data
processing hardware, test the
material from two sides as it
passes by, identifying defective
kernels. These are removed by
ejection nozzles at the end of
the chute. Each second, over
100,000 kernels are checked. |
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