Note: Descriptions are shown in the official language in which they were submitted.
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ANIMAL FEED IN PELLET FORM,
PROCESS AND APPARATUS FOR PREPARING SAME
TECHNICAL FIELD
The present improvements relate to a feed in pellet form for animals,
particularly livestock,
and processes for preparing it. More specifically, the improvements relate to
animal feed
produced by agglomeration of ingredients in powder form.
BACKGROUND
It is well know that in order to produce and maintain healthy animals, such as
cattle, they must
be fed with balanced foods such as cereals, and certain additives or
supplements such as
minerals, vitamins, medicaments, and the like. Food supplements are typically
provided in the
form of powders, a form which is easily produced industrially. However,
animals are not very
attracted to powders, even if mixed in with other foods, and have been known
to refuse food
supplements provided in this form. Therefore, it has been known for decades to
provide
animal feed in the form of pellets which include some food materials and some
food
supplements mixed together. However, the existing methods and processes for
producing such
feeds, as well as the feeds themselves, experience several drawbacks.
Some existing processes make use of binders to join the feed materials
together. One
drawback of using binders is their additional costs, and the fact that not
every binder is good
for animals to ingest. Some processes make use of high temperatures to bind
the feed
materials together. A drawback of this is that high temperatures tend to
destroy at least some
of the quality nutrients like vitamins. In other known processes, the
nutrients are mixed with
other materials to provide adherence of the materials into pellets, and/or to
render the products
adapted to use with their machines. Typically, these processes result in
pellets which have a
low concentration of nutrients and therefore occupy a relatively high volume,
which renders
them somewhat cumbersome to handle. In other processes, pellets of a
predetermined size are
obtained by separating an agglomerated chunk into pellets by means of a die.
In these
processes, the size of the feed is preset by the die, and is therefore
adjustable only by using a
die having a different dimension. In still other processes, pellets are
submitted to compression
during production, which is believed to have drawbacks as well.
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In view of the above, it is seen that there remains a need in the art for
improved animal feeds,
and for processes of making animal feed as well. Among several other needs,
there is a need
for an improved animal feeds which provides the following characteristics:
include some
desired food supplements, are well accepted andlor digested by the animals,
are nutritive for
the animals, are available at relatively low cost and are relatively easy to
handle.
SUMMARY
It is an aim of the improvements to provide a feed for animals, particularly
livestock, that is
substantially free from dust, relatively cheap to produce, and which is well
accepted by the
animals.
It is another aim of the improvements to provide a manufacturing process that
lends itself to
produce animal feed including a choice of ingredients selectable by the
customer.
It is another aim of the invention to produce a high-yield feed which has a
relatively high
concentration of nutritive ingredients, and which therefore occupies less
volume and is easier
to handle, for the animal to receive the benefits of a full ration of
nutrients while eating a
lesser quantity.
It is another aim of the improvements to produce a feed which provides a high
level of
absorption of nutritive ingredients upon digestion by the animal. In one
aspect, the feed is not
compressed during processing and is therefore porous and easily digestible by
enzymes in the
stomach of the animal.
It is a another aim of the improvements to provide a process and apparatus
which can produce
animal feed of easily adjustable dimensions.
In accordance with an aspect of the invention, the improvements provide a
process for
pelletizing animal feed. The process comprises: providing a powder composition
into a drum,
the drum having a disc, a circumferential wall integral with the disc, and an
axis of rotation
normal to the disc and inclined relative to a vertical axis, the drum being
rotatable about said
inclined axis and defining an upper and lower zones through which the disc
passes during
rotation, the powder composition consisting of powders of a food-grade
hydraulic binder, a
food-grade phosphate salt, and at least one substantially insoluble feed
ingredient; whereby
when the disc is rotated some of the powder composition is carried towards the
upper zone,
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and some of the powder composition tumbles towards the lower zone by gravity;
and then
spraying water onto the powder composition as the drum is rotated so as to
cause the powder
composition to agglomerate into pellets of animal feed.
In accordance with another aspect of the invention, the improvements provide
an apparatus
for producing animal feed in pellet form by agglomeration from a powder
composition in the
presence of water; the apparatus comprising: a drum, the drum having a disc
and a wall
circumferential to the disc, the drum being rotatable around a rotation axis
thereof, the
rotation axis being normal to the disc and being inclined with respect to a
vertical axis,
defining an upper zone and a lower zone through which the disc passes during
rotation; at
least one spray nozzle adapted to spray water onto a portion of the disc
during rotation;
whereby the powder composition can be tumbled, moistened, and agglomerated
into pellets
within the rotating drum.
In accordance with another aspect of the invention, the improvements provide a
method of
preparing animal feed in pellet form, the method comprising: providing a
powder composition
including powder feed ingredients mixed together, the powder composition being
capable of
agglomerating into pellets in the presence of water; providing an appropriate
amount of water
to the powder composition while tumbling the powder composition, thereby
causing the
powder composition to agglomerate into pellets.
In accordance with another aspect of the invention, the improvements provide
an animal feed
pellet made from a powder composition, the powder composition consisting
substantially of
an agglomeration of insoluble particles of animal feed ingredients, a food-
grade phosphate
salt, and a food-grade hydraulic binder, each pellet having a moisture content
of between 5
and 20%, and being further characterized by a porous consistency thereby
providing an
increased surface exposure during digestion by an animal.
In some more specific embodiments, the food-grade hydraulic binder used is
magnesium
oxyde, and the food-grade phosphate salt is mono-dicalcium phosphate.
As used in the present specification and in the appended claims, the terms
Pellet Durability
Index (PDI) and coefficient of variability are defined as follows:
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Pellet Durability Index: it is a measure of the durability of pellets. The
degradation of the
pellet during handling is estimated with a durability tumbling tester. It is
the weight of the
pellets after shaking divided by the weight before shaking, which is then
multiplied by 100. A
Borregaard Pellet Durability Tester was used for our tests.
Coefficient of variability: the coefficient of variability (C.V.) is provided
as an estimate of the
precision of the data with respect to the mean. This coefficient is calculated
by dividing the
standard deviation by the mean which is then multiplied by 100.
DESCRIPTION OF THE FIGURES
Further features and advantages of the present invention will become apparent
from the
following detailed description, taken in combination with the appended
drawings, in which:
Fig. 1 is a schematic view of a setup of a process for producing animal feed
in pellet form in
accordance with one embodiment of the improvements;
Fig. 2 is a front elevation view of a drum of the setup of Fig. 1; and
Fig. 3 is a side elevation view of the drum of Fig. 2.
It will be noted that throughout the appended drawings, like features are
identified by like
reference numerals.
DETAILED DESCRIPTION
The starting powder composition can include various feed ingredients and
combinations
thereof, and the composition of the pellet product obtained from the process
can thus be
adapted to the choice of a customer. The size of the pellets can also be
selected, this will be
discussed below.
In an embodiment, the powder composition includes magnesium oxyde and mono-
dicalcium
phosphate. The magnesium oxyde and mono-dicalcium phosphate are made part of
the
powder composition, and the powder composition is submitted to moistening
during tumbling.
The moistening of the powder composition contributes to the snowball
agglomerating effect
of the free particles into pellets. The moistening also generates an
exothermic reaction. The
rate at which the water is provided influences the temperature increase due to
the exothermic
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reaction. By limiting this rate, the heat-sensitive ingredients of the powder
composition are
preserved.
We have found that the snowball effect takes place when both magnesium oxide
and mono-
dicalcium phosphate are present in the powder composition. We have also found
that it is
possible to agglomerate many various types of powder feed ingredients with the
magnesium
oxide and the mono-dicalcium phosphate when they are mixed therewith and
tumbled in the
presence of moisture. However, we have found that sodium bicarbonate powder,
for instance,
impeded the snowball effect. We believe this may also be the case for other
substantially
soluble powders. Further, we have also found that the snowball effect was
enhanced when the
powder composition consisted of substantially non-soluble powder ingredients
in the form of
a relatively fine powder composition, of a fineness similar to flour to the
touch, and that the
use of coarse powders was more difficult to agglomerate into pellets by this
process. A typical
size of powders to be used with the process ranges between 50 and 100 microns.
We also
believe the snowball effect is favored by properly mixing the different powder
ingredients into
a substantially homogeneous powder composition.
In accordance with one embodiment, pellets having improved characteristics are
prepared by
tumbling the water-moistened powder composition in a drum, in the following
manner : the
powder composition is provided in the drum, and a predetermined amount of
water
(preferably between 5 and 8% of the weight of the initial powder composition)
is sprayed in
an atomized state onto the powder composition at the upgoing face of the drum
at the
beginning of the rotation process and until the beginning of agglomeration of
the powder
composition. The exothermic reaction which follows agglomerates the other free
particles
available and results in increasing the size of the agglomerates, into pellets
of a desired size.
This is what we refer to as the snowball effect. If pellets of a greater size
is desired, the
operator can add some powder composition, add water, and further tumble with
the drum, and
the pellets will further increase in size by agglomerating the free particles
of the powder
composition in the snowball effect. The size of the pellets is thus easily
adjustable.
The ideal amount of water to be used depends on the specific ingredients
provided in the
powder composition, and which are in a large part selected as a function of
the ingredients
which are desired in the final pellet product. The specific powder composition
will thus be
dictated by the ingredients a customer will desire to have in his pellets. As
a general rule,
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however, it can be said that there needs to be a sufficient amount of water
used for the
agglomeration and the chemical reaction to take place. If not enough water is
used, there will
remain a quantity of free powder particles in the feed. The minimal amount of
water to be
used is typically of about 5% by weight of the powder composition, and only
rarely lower. At
the other extreme, if too much water is used, the pellets tend to be less
resistant, too moist,
and have a tendency to break down into chunks. If there is too much water, the
moisture
content can be lowered by evaporation following formation of the pellets, but
preferably, this
latter step is avoided by selecting the right percentage of water to start
with. Typically, the
percentage of water sprayed does not exceed 8%. However, higher percentages
may be
desired in certain applications. For example, a concentration of 11 % has been
found suitable
to agglomerate certain types of powder compositions. The optimal amount of
water to be
added to a particular powder composition is determined by experimentation with
a small
batch, and once a satisfying result is achieved, the process is used to
produce a larger batch.
Be it noted that the exothermic chemical reaction creates heat, and therefore
creates
evaporation of some of the water. Inversely, the humidity present in the
ambient air tends to
be somewhat absorbed by the pellets, and also affects the humidity
concentration of the final
pellets.
The exothermic chemical reaction which follows the application of water takes
a certain time
(typically of the order of 15 to 30 seconds), and the operator therefore stops
the spraying of
water before the desired diameter is reached, and the pellets will continue to
agglomerate
some free particles and continue to grow, without exceeding the desired
dimensions. In some
embodiments, it is desired to minimize the size of the water droplets into a
fine mist. We
believe the use of a finer mist enhances the snowball effect. Typically, the
use of larger
droplets tend to agglomerate the feed into irregular sizes of pellets, and the
larger pellets
created by a large water drop tend not to dissociate during the process.
As was discussed above, the process can accommodate a wide variety of
substances into the
final pellets, and the choice thereof is largely motivated by the requirements
of the customer.
Some general rules as to the ingredients to be included in the powder
composition can
nevertheless be drawn at this stage. As discussed, one type of binding
reaction was achieved
using magnesium oxyde and mono-dicalcium phosphate with water. Skilled
chemists will
understand that alternative materials also provide similar binding reactions
with water, and for
instance, ingredients used in the formation of concrete may provide similar
results. In the
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making of animal feed, one should make sure that the binding materials used,
and the reaction
products in the finished pellets, if any, are food-grade, non-toxic, and
preferably be nutritive
to the animals.
In this latter example, the magnesium oxide acts as a hydraulic binder. It is
believed that other
types of hydraulic binders can be used, as long as they are food-grade. In an
alternate
embodiment, one could use calcium oxide instead, which should provide similar
agglomeration results. In fact, it is believed that other alkaline earth
oxides could be used as
well.
The mono-dicalcium phosphate is a mixture of mono-calcium phosphate and
dicalcium
phosphate. It is used to provide phosphate to the animals, but is also
believed to play a role in
the agglomeration process. It is believed that other types of food-grade
phosphate salts, such
as mono-ammonium phosphate, would provide comparable results.
[0001] Further, some materials are more favorable to the agglomeration than
others. Some
mono phosphates, for instance, have been found more conducive to the snowball
effect, or
agglomeration. Other materials are not favorable, and are preferably avoided
or used in lesser
percentages, such as bentonite and sodium bicarbonate for example. Still other
materials are
unfavorable to agglomeration and will be readily avoided by those skilled in
the art. This is
the case of most oils and fatty substances. Fatty substances, for example,
tend to form their
own minor agglomerations with powder particles and act as a wall between
agglomerating
elements. The remaining ingredients which can be agglomerated using the
process is vast.
Turning now to Fig. 1, an typical setup for providing a substantially
continuous pellet
production process is depicted. Typically, a set of ingredients, requested by
a customer, are
milled into a fine powder in a mill 40. The powder ingredients obtained are
then mixed into a
substantially homogeneous powder composition which is brought into a tumbler
10. In the
tumbler 10, water 25 is regularly added and pellets 34 are produced (see Fig.
2). The pellets
34 fall out of the tumbler 10 are passed through a sieve 42 which eliminates
pellets which are
of undesired size. In this embodiment, the sieve 42 consists of a cylindrical
mesh having two
sections corresponding to two mesh sizes, and which rotates about an axis
which is slightly
off the horizontal. The pellets 34 exiting the sieve 42 can then optionally go
through a dryer
44, and flavors or scents can be added 46, before obtaining the final pellet
product 48.
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In one embodiment, depicted in Figs 2 and 3, the tumbler 10 includes a drum 11
having a
large inclined disc 12 and a circumferential wall 14 of a fixed height. The
drum 11 rotates
about a rotation axis 16 intersecting the plane of the disc 12 at its center.
The rotation axis 16
of the drum is inclined with respect to the vertical 18 by a predetermined
angle a. Typically,
the angle a will be about 75 degrees from the vertical, and can easily vary
between 55 and 75
degrees in different applications. The drum 11 rotates about its inclined axis
16, and therefore
can be said to have a high zone 20 and a low zone 22 during rotation.
Typically, the rotational
speed of the drum is between 20 and 120 RPM.
The powder composition 24 in the drum 11, prior to moistening, tends to
accumulate in the
low zone 22. The rotation of the drum 11 continuously brings the powder
composition 24
towards the high zone 20, but the powder composition 22 tends to fall, or
roll, back towards
the low zone 22 under its own weight due to the inclination of the disc. For
agglomeration,
water 25 is sprayed, typically in a fine mist by spray nozzles 26, 28, onto
the powder
composition 24 at the area where the latter is brought towards the high zone
20 by the drum
11, where it tends to agglomerate into pellets 30. The agglomerated pellets 30
roll back atop
the upcoming powder composition 24 (being carried by the disc 12) towards the
low zone 22.
Typically, if the drum rotates in a clockwise direction, and the uppermost
point on the high
zone 20 can be said to be at twelve O'clock, The spray nozzles 26, 28 will be
placed at eight
or nine O'clock.
The biggest pellets 30 tend to accumulate at the top, whereas the smaller
pellets 32 tend to fall
into the interstices between the larger pellets and accumulate underneath. The
tumbling
pellets 30, 32 maintain a rolling movement during agglomeration, and therefore
tend to be at
least somewhat spherical. In a preferred application, water 25 and powder
composition 24 are
regularly added within the drum 11, and the larger pellets 34 regularly fall
out the
circumferential wall 14 at the low zone 22 of the drum. This becomes a
somewhat steady
process and in certain types of feed, the machine can be left alone for an
hour or so. However,
it is often desirable that a skilled technician remain close to the machine
and regularly adjusts
certain parameters such as disc inclination, rotation speed, flow rate of
water through the
nozzles, and the like, to keep the pellet production in a substantially
optimized state. For a
predetermined type of powder composition 24, both the inclination a of the
disc rotation axis,
the rate at which water is provided to the composition, and the speed at which
the drum 11
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rotates affect the size of the pellets 34 created, and by adjusting these
parameters, the pellet
diameter can be controlled.
In many applications, the agglomerating nature of the moistened powder
composition 24
results in it sticking to the drum 11. To maintain the tumbler 10 in proper
operating
conditions, a scraper 36 is used. The scraper 36 is fixed to a non-rotating
component, and
abuts the rotating disc 12 to remove some adhered powder composition 24.
Typically, the
scraper 36 is placed around ten O'clock. A second scraper 38 placed, for
example, at two
O'clock can additionally be used to complete the work of the first scraper 36.
It is thus possible with a single machine to provide a wide range of pellet
sizes, as well as a
wide variety of pellet compositions. Since the mean size of the pellets can be
easily adaptable
for each batch of pellets produced, it becomes possible to adapt the size of
the pellets to new
automatic feed distribution systems which require pellets of specified
dimensions.
Other types of tumblers than the one described above can be used to provide
the
agglomeration process of the pellets. Among other possible alternatives, one
prototype we
created made use of a hollow cylinder having a closed end and an open end, the
hollow
cylinder being cantilevered at its closed end and rotatable about a horizontal
rotation axis (not
illustrated). However, problems related to the control of the pellet
uniformity, and time lost
stopping the cylinder to retrieve the pellets, has motivated us to discontinue
research and
development work on this latter prototype in favor of the model proposed,
which has been
found to provide satisfying results. In the case the proposed model is used,
it is desirable that
both the rotation speed of the drum and the inclination of the axis of
rotation thereof be
adjustable to accommodate the many possible types of feed compositions.
The fact that the size of the agglomerations increase in a proportional manner
to the surface of
contact, it is possible to substantially predict the evolution of the diameter
of the pellets during
the agglomeration process. By providing the water in the form of a mist with
appropriate
spray nozzles, it is possible to finely tune and control the amount of water
provided and the
rate at which it is provided, and thereby control the increase in internal
temperature stemming
from the exothermal reaction. By limiting the increase in internal
temperature, heat-sensitive
labile substances such as some vitamins are protected from destruction by
heat, and the
overall nutrient concentration of the pellets is enhanced.
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It will be noted that in the embodiments described above, pellets are produced
with no
compression other than that of their own weight. The process is thus somewhat
delicate, and
produces pellets which are relatively porous. We noticed that the absorption
of the nutrients
by the animals that had eaten pellets produced by the above-described process,
was higher
than for animals which had eaten pellets that were prepared by processes in
which the pellet
was compressed. We therefore believe that the porosity of the product obtained
by our process
enhances its digestibility by the enzymes in the stomach of the animal,
compared to
compressed pellets, and that the compressed outer surfaces of the compressed
pellets may
somehow limit or slow the digestion process.
Many known equipments for producing pellets require certain classes of food
materials which
are adapted to pass through these devices. Typically, manufacturers using such
equipments
need to adapt the composition of their feed to their equipments. In some
applications, the
desired food materials are diluted among other materials which facilitate the
passing of the
composition through the equipments. In some applications, the materials are
selected as a
function of the minimal volume which is to be produced. For these and other
reasons, these
methods and processes have notable constraints which have important cost-
related
consequences.
It will be noted that the improved process, we devised, does not necessitate
any dilution of the
desired food materials. The resulting pellets thus have relatively
concentrated amounts of
nutrients. Further, the animal does not need to ingest such a large amount for
it to receive the
benefits of the prescribed dosage of nutritive elements. The experiments made
on animals
have shown that a highly satisfying amount of nutrients was absorbed by them
when using the
improved feed.
Further, since the feed is relatively concentrated in nutrients, it occupies
minimal volume and
is relatively easy to manipulate during handling, shipping and storage. In
this modem day and
age, where large farms are abundant, where automated feeding systems are
commonly used,
and where competent workers are harder and harder to find, we believe this
ease of
manipulation of an animal feed without compromising its nutritive value to be
one great
advantage.
Hence, and as it will be seen in the following examples, the feed hereby
produced can include
many different types of feed ingredients which can be selected by a customer.
Some examples
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of feed ingredients are food materials and food supplements, and can be
provided in different
combinations thereof. Examples of food materials include cereals such as
wheat, corn, oat,
rye, canola, barley, mixtures thereof, and/or by-products thereof, as well as
salt, for example.
Examples of food supplements includes powder substances based on phosphorus,
calcium,
magnesium, sodium, chlorine, copper, iron, iodine, manganese, selenium or
zinc. Other
examples of food supplements include vitamins, medicaments, or mixtures
thereof, which are
substantially preserved throughout the process and are included in the
pellets. The exact
choice of feed ingredients can therefore be various and is left entirely to
one skilled in the art.
The moisture content of the feed is relevant to the agglomeration of the
powder composition
into pellets. The moisture content is preferably between 5 and 20% by weight
of the powder
composition used, but it may differ with the types of materials used in the
powder
composition and the characteristics desired of the final feed. The exact
choice thereof in view
of specific applications is left entirely to those skilled in the art.
EXAMPLES
The invention is illustrated but is not limited by the following examples.
EXAMPLE 1
One metric ton of a granular feed was prepared by a process as described
above. The
ingredients include the following:
Ingredient Qty (kg)
wheat: 15 kg
calcium carbonate: 55 kg
magnesium oxide: 75 kg
mono-dicalcium phosphate: 487 kg
calcium chloride 233 kg
vitamins, medicaments, dyes 45 kg
water enough to obtain moisture content
The granules obtained are substantially spherical, are of generally uniform
size between 3mm
and 6mm, they have a moisture content of 12.5%, they have a PDI of 98.9 and a
coefficient of
variability of 1.13 for phosphorous, 4.55 for calcium, 1.18 for magnesium and
2.20 for
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sodium on a dry basis. This feed was given to livestock and was well accepted
by all unlike
the counter part that is used in powder form.
EXAMPLE 2
A granular feed was prepared as in example 1 except that it contained the
following:
Ingredient Qty (kg)
wheat: 383 kg
mono-ammonium phosphate 173 kg
magnesium oxide 80 kg
mono-dicalcium phosphate 232 kg
vitamins, medicaments, dyes 42 kg
water enough to obtain moisture content
The granules obtained are substantially spherical, are of generally uniform
size between 3mm
and 6mm, they have a moisture content of 11.5%, they have a PDI of 99.9 and a
coefficient of
variability of 1.08 for phosphorous, 5.12 for calcium, 0.37 for magnesium and
2.93 for
sodium on a dry basis. This feed was given to livestock and was well accepted
by all unlike
the counter part that is used in powder form.
EXAMPLE 3
A granular feed was prepared based on the following powder ingredients :
Ingredient Qty (kg)
monoammonium phosphate 260.20
manganese oxide 60% 11.78
magnesium oxide 56% 135.20
dicalcium phosphate 21/17.5 454.08
zinc oxide 77.5% 9.19
fine salt 55.70
ferric sulphate 30% 12.30
dairy premix 61.55
EXAMPLE 4
A granular feed was prepared based on the following powder ingredients :
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Ingredient Qty (kg)
fine wheat 13.7% 75kg/hl 36.50
limestone -20/+100 302.30
manganese oxide 60% 11.75
magnesium oxide 56% 134.50
dicalcium phosphate 21/17.5 428.62
zinc oxide 77.5% 9.11
fine salt 54.40
dairy premix 22.82
EXAMPLE 5
A granular feed was prepared based on the following powder ingredients :
Ingredient Qty (kg)
limestone -20/+100 59.30
magnesium oxide 56% 81.60
dicalcium phosphate 21/17.5 536.10
fine salt 256.00
vitamin and mineral premix 47.00
dairy premix 20.00
Using the ingredients given in example 5, a feed in granular form was produced
with a
tumbler 10 of the type hereinabove described. The powder composition was fed
to the tumbler
10 at a rate of about 500Kg/hour. The mixed powders had a size varying
typically between 50
and 100 microns. The disc 12 was inclined by about 60 degrees, and rotated at
about 30RPM.
The moisture content of the granules ranged between 12 and 16% depending on
the ambient
humidity.
It is to be noted that the premixes used with the given examples are of the
type commonly
available in the art and typically contain vitamins, minerals and medicaments.
Although the invention has been described with respect to specific
embodiments, it is
understood that modifications are possible provided that they fall within the
scope of the
appended claims.
