Cryogenic Grinding : Seminar Report and PPT
The term "Cryogenics"
originates from Greek word which means creation or production by means of cold.
As prices for energy and raw materials rise and concern for the environment makes
safe waste disposal difficult and Costly, resource recovery becomes a vital matter
for today's business. Cryogenic grinding technology can efficiently grind most
tough materials and can also facilitate Cryogenic recycling of tough composite
materials and multi component scrap. The heart of this technology is the CRYO-GRIND
SYSTEM. It employs a cryogenic process to embrittle and grind materials to achieve
consistent particle size for a wide range of products. The cryogenic process also
has a unique capability for recycling difficult to separate composite materials.
Cryogenic grinding is a method of powdering herbs at sub-zero temperatures ranging
from 0 to minus 70°F. The herbs are frozen with liquid nitrogen as they are
being ground. This process does not damage or alter the chemical composition of
the plant in any way. Normal grinding processes which do not use a cooling system
can reach up to 200°F. These high temperatures can reduce volatile components
and heat-sensitive constituents in herbs. The cryogenic grinding process starts
with air-dried herbs, rather than freeze-dried herbs.
Solid materials are ground or pulverized by way of hammer mills, attrition mills,
granulators or other equipment. A smaller particle size is usually needed to enhance
the further processing of the solid, as in mixing with other materials. A finer
particle also helps in melting of rubber and plastics for molding. However, many
materials are either very soft or very tough at room temperatures. By cooling
to cryogenic temperatures with liquid nitrogen, these may be embrittled and easily
fractured into small particles.
controlled study using four herbs was conducted at Frontier Herbs in the Fall
of 1996, comparing cryogenic grinding methods with normal grinding methods. The
herbs tested included feverfew, goldenseal, valerian and echinacea. In all cases
the cryogenically ground herb contained greater amounts of the constituents tested.
Feverfew herb showed the greatest difference, with the cryogenically ground herb
containing 21.8% higher levels of parthenolide, the primary active constituent.
Valerian root showed an 18.7% increase in valerenic acid when cryogenically ground.
Goldenseal root showed a 16.4% increase in berberine and 10.7% increase in hydrastine.
Lastly, Echinacea purpurea root showed a 12.1% increase in total phenolic content
in the cryogenically ground root. Test results were obtained by HPLC (high performance
liquid chromatography) methods.
grinding was shown to significantly affect active constituent levels in herbs.
Test results showed an average increase of 15.6% in constituents tested in four
medicinal herbs when they were ground cryogenically. The range was 10.7% to 21.8%,
indicating that some herbs are affected more than others by the temperatures at
which they're ground.
Since almost all materials embrittle
when exposed to cold temperatures, cryogenic size reduction utilizes the cold
energy available from liquid nitrogen to cool, embrittle and inert materials prior
to and or during the grinding process. All materials which due to their specific
properties at ambient temperatures are elastic, have low melting points, contain
volatile or oily substances, have low combustion temperatures and are sensitive
to oxygen, are ideal candidates for cryogenic size reduction.
Physical properties of liquid nitrogen is produced by the separation of air into
its components in an air separation plant and is distributed in vacuum insulated
transport vessels to the end user where it is stored in a vacuum insulated storage
vessel till it is used. At atmospheric pressure liquid nitrogen is at a temperature
of -320 deg F and possesses a latent energy content of 94 BTU/LB resulting in
a total cooling energy content of 179.6 BTU/LB. Nitrogen is anon-flammable, non
toxic and inert gas which makes up 78.09% of the air we breathe.
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