Note: Descriptions are shown in the official language in which they were submitted.
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CONFIRMATION
TITLE: GRANULAR MATERIAL GRINDER AND METHOD OF USE
BACKGROUND OF THE INVENTION
The grinding of particulate matter has involved a number of different
approaches all
of which present varying problems. Grinders in the prior art typically use
blades or
impellers to mechanically break down granular material into smaller pieces.
However, this
mechanical breakage is limited to the interaction of the blades or impellers
upon the
granular material. Accordingly, it is an objective of the present invention to
create an
environment which is influenced by impellers but does not require direct
contact by the
impellers upon the particulate matter to greatly reduce size.
Also in the prior art, grinders have been developed which grind material in a
water
or liquid environment in order to achieve a reduced particle size. However,
water or liquid
processing creates problems such as the leaching of soluble solids from the
granular
material and also creates the high energy problem of removing the water or
liquid once the
granular material is ground into powder. Accordingly, a further objective of
the present
invention is the provision of a granular material grinder that reduces
particle size without
the use of a water or liquid as a carrier.
U.S. Patent Number 2,752,097 to Lecher discloses a grinder for producing ultra
fine
particles which creates vortexes around rotating paddle wheels which causes
particles to
strike the outside wall. However, Lecher is a low volume system that creates
high heat that
must be cooled with a large air volume. In addition, the Lecher environment is
subject to
stresses that may damage the equipment. Accordingly, a further objective of
the present
invention is to produce a granular material grinder that does not emphasize
particle
collision with the inside of the chamber or impellers and has a lower
operating temperature.
The market place is demanding materials that are microground and yet their
chemical composition is not changed. For example, even slight changes in
chemical
compositions of pharmaceutical products or dietary supplements may inactivate
the
chemical composition or physical characteristic. Accordingly, a still further
objective of
the present invention is to control the operating parameter such that the
temperature, carrier
gas, and mechanical interaction do not damage these critical commercial
products.
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Another objective of the present invention is the provision of a method and
process
for grinding granular material that is economical and safe.
These and other objectives will become apparent from the following
description.
BRIEF SUMMARY OF THE INVENTION
The foregoing objectives may be achieved by an apparatus for grinding granular
material having a hammer mill that reduces incoming granular material into
particulate
material that is temperature controlled, a microgrinder receiving the
particulate material
from the hammer mill that has an impeller rotatably mounted that accelerates
the
particulate matter to strike against itself to create microground product, and
a product
collector which collects the microground powder so that it may be packaged.
The foregoing objectives may also be achieved by a process for grinding
granular
material that involves a first grinding step which reduces the size of grain
into particulate
pieces for mechanical breakage, a second grinding which reduces the size of
particulate
pieces through particulate piece to particulate piece collisions to form
microground
product, and a separating step to remove the microground product from the
particulate
pieces.
The foregoing objectives may also be achieved through a method of grinding
particulate matter comprising suspending particulate matter in a flow of
carrier gas and
propelling particulate matter using the impeller to strike against a
particulate matter going
toward the impeller to fracture the particulate matter.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a plan layout of the granular material grinder.
Figure 2 is an enlarged view of the hammer mill as seen in Figure 1.
Figure 3 is an enlarged view of the microgrinder and product collector as seen
in
Figure 1.
Figures 4A-C are an enlarged view of particulate matter colliding to form
microground product.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The granular material grinder of this invention is referred to in Figure 1
generally
by the reference numeral 10. The granular material grinder 10 is used to grind
whole grain,
such as corn, soybeans, wheat, etc., or other products such as gravel or coal.
The granular
material grinder 10 grinds these granular products into a microground powder.
As seen in Figure 1, the granular material grinder 10 of the present invention
is
completely sealed to the atmosphere. In this completely sealed configuration,
the granular
material grinder 10 operates with a 100% recovery of the granular material 12
placed into
the granular material grinder 10. The grinder 10 could also be operated open
to the
atmosphere, however, in this configuration product is lost and a carrier gas
such as nitrogen
cannot be used.
As seen in Figures 1, 2, and 3 particulate matter 12 is placed in hopper 14
which is
then sealed. Valve 16 is then opened allowing product to drop from the hopper
14 into a
feed hopper 18. The valve 16 illustrated is a manually operated gate valve;
however, the
valve may be operated electronically, pneumatically or hydraulically and may
be a butterfly
gate or of another configuration.
The feed hopper 18 empties into an auger 20 which is powered by motor 22. The
auger 20 pushes granular material 12 into the hammer mil130. The hammer mi1130
has a
hammer mill housing 32 having a chamber 34 therein. The hammer mill housing 32
has a
granular material inlet 36 and a carrier gas inlet 38. The hammer mill housing
32 also has
outlet 40A and 40B.
A screen 42 is placed within the carrier gas inlet 38 to increase the velocity
of
carrier gas passing through the hammer mill 30. Inside the hammer mill housing
32 are
rotating hammers 44 attached to shaft 46 and driven by motor 47. The screen 42
also acts
to keep the granular material 12 in contact with the hammers 44.
The auger 20 pushes granular matter 12 into the hammer mill housing 32. The
drive motor 47 rotates hammers 44 to impact upon the granular matter 12 and
reduces the
size of the granular matter 12 through impact to produce particulate matter
48.
A mechanical separator 50 is provided to accelerate carrier gas 64 that is
without
any particulate matter. The mechanical separator 50 may be a blower or a
cyclone
separator. The mechanical separator 50 is adapted to receive a mixture of
carrier gas and
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particulate matter that is being recycled through the system. The mechanical
separator 50
receives this mixture through inlet 52 and separates the carrier gas 64 from
the particulate
matter 48. The mechanical separator 50 then moves the carrier gas through
outlet 54
towards the carrier gas inlet 38 of the hammer mill 30. In addition, the
mechanical
separator 50 feeds the separated particulate matter 48 through the particulate
matter outlet
56. An auger 58 is provided in fluid communication with particulate matter
outlet 56 such
that motor 60 turning the auger 58 places the particulate matter 48 from the
particulate
matter outlet 56 into the hammer mill 30 through recycled particulate matter
inlet 62.
The carrier gas 64 generally has no significant particulate matter within it;
however,
the presence of particulate matter within the carrier gas 64 is not
troublesome unless it is
larger than the holes present in the screen 42. The carrier gas 64 enters the
hammer mill 30
through the holes in the screen forcing product inward against the normal
centrifugal force
of the hammer mill 30 and out through outlet40A and through screen.42 and
through
outlet 40B.
The velocity of the carrier gas 64 can be regulated by the number and size of
the
holes in screen 42 and the volume of carrier gas vacuumed through outlet 40A.
The
vacuum at outlet 40A is regulated by the revolutions per minute (RPM) of the
fan motor
78. The greater the flow of carrier gas 64 the greater the velocity of the
carrier gas 64
through the screen 42 in hammer mill 30. If the volume of carrier gas 64
remains constant,
the larger the holes and/or the increase in number of holes in screen 42 will
result in a
lower velocity of carrier gas 64 through the hammer mill 30.
The more volume of carrier gas 64 through the hammer mill 30 the more cooling
effect and the lower the operating temperature of the grinding process.
Fan 70 has an inlet 72 joined in fluid communication to outlets 40A and 40B by
pipe having an inlet 72 and outlet 74 with fan blades 76 therebetween. The fan
70 is
powered by fan motor 78. The fan 70 picks up particulate matter 48 that has
gotten
through the screen 42 and is dropping through the opening 40B. The combination
of the
two products from outlets 40A and 40B are then transferred by the fan 70 to a
connecting
pipe to a microgrinder 80. As shown in Figure 1, only one microgrinder 80 is
shown;
however, in practice, several microgrinders 80 and particle collectors 120 may
be used for
each hammer mill 30 to increase the output of the system 10.
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The microgrinder 80 has a column 82 with a cavity 84 with a microgrinder inlet
86
with a positioning pipe 88 mounted within the microgrinder inlet 86. The
microgrinder
inlet 86 is in fluid communication with the fan outlet 74.
The microgrinder 80 has a top section 92, a medial section 94, and a bottom
section
96. The column 82 tapers downward from narrow to wide in the top section 92, a
taper
downward from narrow to wide in the medial section that is greater than the
top sections
taper, and a taper downward from wide to narrow in the bottom section 96.
Alternatively,
the top section 92 may be straight or tapered, larger at the top and small at
the bottom.
Alternatively, an optional straight section 95 between the medial section 94
and bottom
section 96 may be used if more impellers are added to increase the
displacement area of the
impact zone.
Particulate matter 48 exits the positioning pipe 88 to strike at least one
impeller 98
rotatably mounted in the column adjacent the microgrinder inlet 86. The
impeller 98 has
opposite sides, one of the sides having a plurality of impeller blades 100
thereon for
accelerating particulate matter 48 and producing vortex andlor other formation
in carrier
gas 64. As shown in Figure 1, three impellers 98 are located under the
positioning pipe 88.
Two impellers 98 indicated by 102 are facing upward. One impeller 98
identified with
numeral 104 has its impeller blade 100 facing downward. All three impellers 98
are
attached to shaft 106 and driven by motor 108. These impellers 98 produce
vortexes; high
and low pressure zones, and/or turbulence in which particulate matter 48 is
exposed. The
impellers 98 may be varied from upward or downward facing blades depending on
the
product being ground and the shape/size of vortex desired. In some instances,
the impellers
may have both upward and downward impeller blades.
As shown in Figures 4A-C, the particulate matter 48 is impacted against one
another due to the different effects of vortexes, high and low pressure zones,
and/or
turbulence on various sized particulate matter 48.
The hammer mill 30 is the first grinding step. The hammer mill 30 produces a
variety of sizes of particulate matter 48. The efficiency of the grinding
process in the
microgrinder 80 is improved by having varied size particles to impact with
each other.
The desired result within the microgrinder 80 is to produce vortexes, high and
low
pressure zones, and/or turbulence at an intensity so that the larger particles
pass through
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with little effect while the smaller particles will have their direction
altered. The smaller
particles are spun in a circular motion within the relatively small vortexes
created within
housing 82 causing them to cross paths with the larger particles and impact
them.
These random collisions between particulate matter 48 cause the particulate
matter
48 to fracture and reduce in size to microground product or powder 114. The
random
collisions are regulated by the speed and shape of the impellers 98 which are
controlled by
the RPM of motor 108. Adjustments may also be made by adjusting valves 112
which
regulate recycled or regrind product particulate matter 48 and carrier gas 64.
Adjustments
to the valve 148 regulate the upward flow of carrier gas 64 and microground
powder 114
into collection chamber 120.
Microground product or finely ground powder 114 moves upward partially because
of static electricity, partially by upward movement of carrier gas 64
regulating by valve 148
and partially by the decreasing radius shape of housing82._
Heavier particles work there way downward due to the shape of housing or
column
82, because of gravity, because of the low velocity of the fluidized bed not
being able to
hold larger particles in suspension, and partially due to centrifugal force.
The centrifugal
force assists in the separation because larger particles are forced to the
conical inner outer
surface of the microgrinder 80 whereas the microground product 114 moves
upward
through the center core of the microgrinder 80.
Therefore, the three factors which affect the final grind are the impellers 98
shape,
design, upward or downward position, and speed; the housing shape, design, and
position
relative gravity; and the flow of carrier gas 64 in the housing 82. The
impeller design 98 is
primarily responsible for the creation of the vortexes in the housing 82.
Smaller vortexes
hold smaller, lighter particles for a longer amount of time in an impact zone
with larger
particles providing the opportunity for finer, smaller particles sizes to be
created.
The housing 82 can be matched to the impellers 98 to give some variance in the
vortex size because the vortexes are formed in the space between impellers
outer edges and
the inner wall of the housing 82. By altering cones and rings upon the housing
82 the
impact zone can be altered to obtain the desired effect in grinding
efficiency. In addition,
by increasing the flow of carrier gas 64 in the housing 82 the volume of
microground
powder 114 processed will increase. Particulate matter 48 may then be
increased requiring
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more particulate matter 48 to be transported back to the hammer mill 30
through the
recycled particulate matter 48 pipe. The carrier gas 64 flow in the housing 82
can be
increased or decreased conversely by increasing or decreasing the cross
sectional area or
tapers changing the column 82 at any given point.
The granular material grinder 10 has a product collector 120 positioned above
the
microgrinder 80. The product collector has a shell 122 with a collection
chamber 124
formed therein. The shell 122 having a collector inlet 126 and a collector
outlet 127. The
collector inlet 126 is in fluid communication with the microgrinder outlet 90.
The product
collector 120 has an inner surface 128. Wipers 130 attached to shaft 132 and
driven by
motor 134 clean microground product from the inner surface 128 of the product
collector
120. The wipers 130 drop the microground powder 114 from the inner surface 128
to the
product collector outlet 127 to the product hopper 140.
The product hopper 140 is in fluid communication with the collector outlet
127.
The product hopper 140 has an inlet 142, a recycled outlet 144, and a valve
148 attached
controlling the amount of carrier gas 641eaving the outlet 144. Attached to
the bottom of
the product hopper 140 is an auger 150.
The product hopper 140 is filled thorough the normal operation of the wiper
system.
Opening valve 154 and rotating auger 150 by auger motor 152 fills a product
bag (not
shown). Valve 154 is then shut to replace a product bag. The valve 154 is
closed between
filling product bags to maintain the seal throughout the entire granular
material grinding
system.
Carrier gas 64 is recycled from the product hopper 140 back through the
process
where it joins with a mixture of particulate matter 48 and carrier gas exiting
the recycled
outlets 110 of the microgrinder 80. These combined recycled streams are in
fluid
communication with the recycled mixture inlet 52 of the mechanical separator
50. As
mentioned previously, the mechanical separator 50 creates a stream of carrier
gas 64 and a
particulate matter stream that exits out the particulate matter outlet 56.
When operated in a.closed loop, 90-100% of the entering granular material is
recovered as microground product and preferably 98-100% of the entering
granular
material is recovered as microground product. When operated continuously 100%
of
entering granular material is converted to microground product.
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The carrier gas 64 is recycled continually throughout the entire process. The
carrier
gas may be atmospheric air or an inert gas such as nitrogen. When using an
inert gas the
gas is entered into the process using a cylinder 160 of nitrogen gas connected
to the piping
of the granular material grinder 10. As shown, this nitrogen is attached at a
point of the
carrier gas outlet of the mechanical separator 50. However, the inert carrier
gas may be
placed into the system at other numerous places of the system. Alternatively,
the carrier
gas may be a reactionary gas chosen to change the chemical and/or physical
properties of
the microground product 114.
In addition, a refrigeration system 162 may be used to control the temperature
of the
carrier gas. Alternatively, a refrigerated cooling jacket may be around any
portion of the
system 10 or all of the system 10 to control temperature. The process is
operated in a
closed loop to maintain the system, particulate matter, microground powder and
carrier gas
between 50-100 F and preferably between 50-70 F. These temperatures are
preferred
because of the reduced risk of degrading viable components of whole grain
entering into
the process. If the microground powder is a pharmaceutical, vitamin, or other
neutraceutical there may be different preferred temperatures to protect the
integrity of the
microground powder. The refrigeration system is located at the carrier gas
outlet of the
mechanical separator 50 to minimize damage to the refrigeration system that
may be
encountered because of particulate matter entering the refrigeration system.
As shown, the granular material grinder 10 is manually controlled by adjusting
the
valves and RPM of the motors. Alternatively, a programmable control system may
be
employed to control the granular material grinder 10.
The invention has been shown and described above with the preferred
embodiments, and it is understood that many modifications, substitutions, and
additions
may be made which are within the intended spirit and scope of the invention.
In the
foregoing, it can be seen that the present accomplishes at least all of its
stated objectives.
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