Note: Descriptions are shown in the official language in which they were submitted.
2 ~ 8 ~
COATING DE~ICE
Thi~ invention concerns a device ~or smoothing
out a fluid coatlng applied on particulate material.
Especially preferred ls a device for soothing out a
~luid coating, for example a pesticide, on seeds.
It i~ increasingly attractive to seed suppliers
to apply to agricultural seeds, coatings of various
materialq, particularly pesticidal materials, which are
able to protect the seeds against attack by, ~or
example, fungi ~nd insects, while the seed is dormant in
the ~oil.
The appllcation o~ coating material~ to large
quantities o~ ~eeds ?re3ent substantial problems. It is
important that the seed should be uniformly coated, and
in order to ensure that this iq achieved, it i9
conventional to apply pesticidal formulations in liquid
2~ form, containing substantial quantities of an inert
liquid ~/ehicle (normally water). The inerr liquid
vehicle must be -emoved, generally in a separate drying
stepl before the treated seed can be bagged and sold.
This procedure normally results in the nee~ for a
37,211-F -1-
- 2 0 ~
separate drying ~tep, which increase~ the expense of the
overall process. It is. therefore. desirable to be able
to apply to the seed the pesticidal substance in a
formulation containing very little inert vehicle, so
that no separate drying step of the pesticide on the
coated product is required, while maintaining
substantially even pesticidal distribution.
Surprisingly, such a coating device has now
been devised. In accordance with thi~ invention, a
device is provided for applying a fluid coating material
to a particulate material. said device ha~ing a
generally upright circular body, which has an in~ide
wall surface defining a flowpath for passage of the
particulate material therethrough, which comprises, a
device for making uniform a fluid coating material to a
particulate material, said device comprising a generally
upright circular body shell, having an inside wall
~urface defining a flowpath for passage of the
particulate material downwardly therethrough, with a)
means for feeding the particulate material to interior
of the the upper part of the body shell promptly after
fluid coating material has been applied thereto, b) a
rotatable sha~t extending upwardly and axially towards
the means for feeding and within and generally along the
length of the body shell, c) an array of agitator
elements spaced along and affixed to the shaft for
rotation therewith, ~he agitator elements each having a
proximal end attached to the shaft and a distal end
directed generally radially towards the said inside wall
surface, and d) means for rotating the shaft within the
body snell at a controllable predetermined constant
rate, wherein successive agitator elements within said
array, are so shaped as to provide decreasing agitation
37,211-F -2-
2 ~ 5
--3--
to the parriculate material~ as ~he material passes
downwardly through the body shell.
In particular, the device is preferred for
applying a pesticidal material to agricultural seeds,
-J although the device is not limited to such application.
The fluid material is preferably a liquid, for example,
an aqueous or non-aqueous pesticidal composition which
may be of conventional form. The device according to
the invention may also be utilized to apply fluid
compositions in powder form.
However, as is readily apparent, the device of
the present invention is not limited to the use of
applying pesticides onto seeds, but may advantageously
be employed to apply selec~ed fluid coating onto
selected particulate ~aterial.
The de~ice comprises a generally upright
circular body shell, having an nside wall surface
2~ defining a flowpath for passage of the particulate
material ~herethrough. Mean~ are provided for feeding
the particulate material to the lnterior of the upper
part of the body, to cause the particulate material to
pass downwardly through the body cavity under gravity.
A rotatable shaft extends generally axially within the
body, and has a plurality of agitator elements spaced
along and affixed to it, for rotation with it. The
agitator elements each have a proximal end attached to
the shaft, and a distal end directed generally radially
towards the inside wall surface of the body. Means are
provided for supporting and rotating the shaft within
the body at a controllable preselected constant rate. A
spray head is provided for applying ~he fluid coating
material (typically, a pesticide) to the particulate
37,211-F -3-
_4_ 2~ 8~
material ~ or e.Yample seeds), ?rior to contact of the
particulate material with the said agitator. The spray
head may ce provided within t:~e upper part of the body,
or externaily of the ~ody sucn that the particulate
material .may be treated prior ~o its entry into the
body.
In one aspect of the invention the agitator
element~ are so shaped as to provide a decreasing amount
of agitation to the ~articulate material as it passe~
downwardly through the body. For example. the agitator
elements n the upper ?art of the body may be generally
in the form of plates of blades. angled so as to direct
the falll-.g particulate material momentarily generally
upwardly -gainst the gravitational flow, wnerea~ the
agitator elements in the lower part o~ the body may be
rodq or bar~ or the like. It is desired to produce
decreasing agitation as the particular material passeq
downwardly through the body to ensure even distribution
over the particulate material. Ihis result is
accomplished when the fluid coating material i~ applied
to particulate material, either immediately before the
coated material enters the body, or within the body
itself, such that it is distributed to cover all of the
~5 available surfaces of the par~iculate material as soon
as po~sible. For this reason, a relatively large degree
of agitat on or shear is initially applied. this amount
being pre~erably to provide as high a level of shear as
is consis~ent with not damaging the material which is
being treated. The ~ower part of the body functionq
mainly ~s a drying chamber. A sufficient -mount of
drying taKes place (?articularly in the case of
agricult~-al seeds) so that ~he material emerging from
the coat ng device can be packed and shipped. Left
37,211-F -4-
201 11 85
undistur~ed, the fluid coating material distributed in
the upper part of the body can tend to cause the
material to agglomerate. so that it is not free flowing.
In order to pre~rent ?ossible agglomera~ion agitation is
provided in the lower part of the body, but this
agitation is of a much lower degree than is provided in
the upper part of the body.
In a second aspect of the invertion, which is
preferably employed in conjunction with the first
aspect, but which may be employed separately, the
agitator element~ are tapered towards thelr radially
extending distal ends in such a manner as to tend to
equalize the shear applied to the particulate material
over the length of the agitator elements. It has been
found that shaping the agitator elements in this way to
equalize the shear applied to the particulate material
along the length of the agitator elements gives rise to
a particularly advantageous distribution o~ the fluid
coating material over the surface of the particulate
material.
In a third aspect of the invention, which may
be employed with one or the other of the ir~t aspects
described above, but which also may be employed alone, a
plurality of baffles are mounted on the inside wall of
the bod-J. ~he Daffles are so positioned 'hat all of the
particulate material pa~sing though the device must
necessarily encounter at least one of the baffles, there
3 being no direct downward straight-line path through the
body by which the baffleq may be avoided. The baffles
preferably extend around substantiallJ the entire
circumference of the said inside wall. The baffles haYe
a deflecting surface so angled aq to face inwardly, so
37,211-r -5-
2 ~ 8 ~
--6--
as to deflect downwaraly flowing particulate material in
a direction generally towards the shaft.
When baffles re employed which do not extend
around the entire circumference of the inside wall,
their leading edges are preferably inclined so as to
disrupt plug rotation of the particulate material, for
example, they may be nclined at an angle of from 30 to
80 to the vertical, ?referably 40 to 70, most
preferably 60, and so angled as to face upwardly, and
thu~ deflect particulate material generally upwardly.
In thi~ aspect of the invention, the baffleq are
somewhat interdigitated with the agitator elements, and
the clearance between the distal ends of the agitator
elements and the ins de wall including the baffles is
Yuch that when the shaft ls rotated at a constant rate,
the shear imparted to the particulate material i3 from
5 to 50 sec-1. Shear is defined to be the difference in
velocity between two layers, divi.ded by the distance
between the layers. r or the present purposes, the
velocity of the layer of particular material adjacent
the agitator element, may be considered to be the same
as that of the agitator element, and the layer of
material adjacent the inside wall surface of the body
may be considered to oe stationary, and the applied
~hear may, therefore, be calculated in terms of the
relative velocity of ~he agitator element tips and the
inside wall~ The rate o~ shear is from 5 to 50 sec~1,
preferably from 10 to 30 sec-1, more preferably
20 sec-1, although this will depend to some e~tent on
the nature of the particul~te material (such as seeds)
being treated. Fragile ?articulate material, for
example pea seeds, will reauire a low shear rate, for
example, 5 sec~ hereas cereal seeds such as wheat or
37,211-F -6-
-7- 2~ 8~
other cereal crop3 will be more suitably treated with a
higher shear rate, for example. 20 sec~1.
The agitators elements may be of any desired
shape, for example they may be circular or 3quare in
cros~ sect on, but as indicated above in a pre~erred
embodiment, are ~haped so as to direct the falling
particulate material generally upwardly, again3t the
gravitational flow. For example, they may be triangular
in cro~ section, or may take the form of an angled
plate, pre~erably having a leading surface which ~orms
an angle o~ from 20 to 75 from the vertical, preferably
60.
It is preferred that the baffles employed in
accordance with the third aspect of the invention ex~end
around the entire periphery of inside wall surface of
the body, because this configuration results in the best
mixing, and allows the shortest possible body length.
It is, however, possible to provide short gaps in the
baffles, provided that such gaps are not aligned with
each other in adjacent baffles so as to provide a direct
flow path for the particulate material9 without
deflection towards the shaft. The deflecting surface of
the baffles is preferably at an angle of from 30 to 80
from the vertical, preferably from 40 to 70, more
preferably 60~.
The device in accordance with the invention
will generally also include measuring means for ensuring
that the appropriate dosage of the fluid material is
applied. Such measuring means may include means for
measuring the flow rate of the incoming particulate
material (e.g., seed) and fluid coating material (e.g.,
pesticide), and may preferably also include means for
37,211-F _7_
2 0 ~
weighing t eated particulate material, and means for
indicating the level of material in the body, for
example, a proximity sensor. The device may also
include means for indicating the dosage rate applied, in
dependence upon the said measuring a~d sensing means.
The invention includes -~ithin its scope a
method for the application of a fluid coating material
(e~g., pesticidal material) to particulate material
te.g., seeds), employing a device as described above.
0 Also included are particulate material thus treated.
A preferred embodiment of the invention will
now be described with reference to the accompanying
drawings.
Figure lA is a schematic elevation, partially
in section and partially in full, of a first embodiment
of a device in accordance with the invention.
Figure lB is a schematic elevation, partially
in section and partially in full, of an alternate first
embodiment o a device in accordarlce with the invention,
Figure 2A is an in section view of the device
of Figure lA, taken along the line 2-2.
Figure 2B is an in section view of the device
of Figure lB, taken along the line ~ ~,
Figure 3 is a schematic elevation, partially in
section and partially in full, of a second embodiment of
a device employing the invention.
Referring to Figure lA, a coating device for
applying a fluid coating material (e.g., pesticide~ to
particulate material (e.g., seeds) is shown, which
37,211-F -8-
2011 ~18~
devlce co~prlses a generally upright circular body shelL
1~ having an inside wall surface 2, defining a flow path
for passage of ~he particulate material. Means not
shown are provided for feeding the particulate material
to the upper part of the body through the feed opening
3, in direction of arrows 4.
Before entering body 1, fluid coating material
is applied to the particulate material, using a spray
head (not shown) of the conventional "rolling cone"
0 type. The particulate material throughput through
opening 3 is such as to maintain the body 1
substantially full of particulate material through the
coating process. Thus 9 the particulate material is
allowed to pass the spray head at a convenient rate so
that the fluid coating is selectively metered onto it.
Centrally located within body 1 is a rotatable
shaft 5, extending generally axially within body 1, and
journalled for rotation in a bearing (not shown) in the
direction of arrow 6. Agitator elements 7 and 8
provided in the upper and lower part of body 1,
respectively, are affixed to the shaft 5 for rotation
t~erewith, and have their proximal ends attached to
shaft 5, and their distal ends directed generally
radially towards surface 2. An electric motor (not
shown) is provided for rotating shaft 5 in the direction
of arrow 6, at a controllable constant rate.
Agitator elements 7 are in the form of angled
blades, and are so shaped as to have a maximum cord line
or width a, shown in Figure 2A, and to taper from the
said maximum chord a both towards shaft 5, and (by
37,211~F -9-
2 0 ~
, o--
virtue of tapered edges 9) towards their distally-
directed tips.
The tapering edges 9 of agitators 7 tend to
equalize the shear applied to the particulate material,
over the length of the agitators (i.e. over the radius
of body l).
The agitator elements 7 are angled so as to
direct the alling particulate material generally
upwardly, against their gravitational flow through the
body, and serve to distribute the fluid coating material
evenly over the surface of the descending particulate
ma~erial.
In the lower part of body l, paddle-like
agitator elements 7 are replaced by smaller agitators 8,
in the form of rods tha~ are More or less circular in
section. The function of rods 8 is not primarily to
further distribute the fluid coating material over the
particulate ~aterial, but instead to agitate the
particulate ~aterial continuously, so the agglomerations
or clumping of the particulate material does not occur.
It has been found that an excess of agi~atio~ to the
particulate material once the drying process has begun
is likely to result in the fluid coating materials being
mechanically removed from the particulate material,
leading to the formation of dust. The agitator elements
8 are thus shaped to provide a gentle agitation, to
minimize such removal.
After traversing downwardly through passage
through body l, the treated particulate ma~erial emerges
passes over a skirt lO at the bottom of shaft 5, and to
37,211-F -10-
2~17 ~
1 1
a discharge hopper indicated generallJ at 11, but not
shown.
Referring now to Figures lB and 2B~ a coating
device generally similar in form to that of the device
of Figures lA and 2A, respec~ively is shown, which
device has stationary baffles 61 which are similar to
the agitator elements 7 of ~igures lA and 2A~ except
that the baffles 61 are fixed to the wall of the body
shell, not to the shaft. The leading edge 60 (Figure
2B) is the edge which first contacts the particulate
material if the shaft is rotated in the direction of
arrow 6, and the agita~or elements 62 form an angle to
the horizon~al.
Referring to Figure 3 or the drawings, a
coating device, generally similar in form to that of the
device of Figures lA and 2A, is shown, which device has
a body 31, with an inside r~all surface 32 defining a
flowpath for particulate material 28.
Means 29, for example a conveyor belt, are
provided for feeding the particulate material ta the
upper part of the body through the feed opening 33, in
direction of arrows 4. The particulate material is ~ed
into the hopper head 46, in either a batch or continuous
process.
The fluid coating is fed to the spray head 38,
and contacts the particulate material within the hopper
head (i.e., prior to the particulate material entering
the body).
Particulate material enters body 31 via opening
33O A shaft 35 is journalled in bearing 36 for rotation
about a vertical axis, driven by an electric motor 42.
37,211-F -ll-
-l2- 2 ~
A spray head 45 or the rolling cone t-rpe applies fluid
coating ma~erial 30 to particulate ma~erial falling
througn the hopper 46, in which the spray head 45 is
~ounted or suspended.
A plurality of agitator elements 37 of
generally eriangular cross-section extend from shaft 35
towards the wall 32. A plurality of baffles 48 are
mounted on wall 32, and each extends around the entire
circumference of the inside wall. Baf fles 48 have a
0 deflecting surface 49 which is angled so as to deflect
the particulate material generally inwardly toward the
shaft 35. ~he baffles 48 are interdigitated with
agitators 37, and have a clearance such as to provide
shear of from ~ to 50 seC~l when the device is in use.
As an example, in a device in which the diameter of body
31 is 0.3 meters, and the gap between the tips of
agitators 37 and surface 49 is 50 mm, a shear rate of
20 sec~l will be achieved at a rotational speed of
64 rpml Generally, it is preferred that the clearance
between the agitators and the inside wall surfaces is
from 25 to 50 mm and the speed of rotation is such that
the distal ends of the agitators have a velocity of from
1 to 2 ~/s.
Treated particulate material leaves the body 31
via a discharge hopper 41, and is caused to discharge
through a gate valve 50a or 50b into a sock 51, which
rests on a weighing device 52. A pair of capascitative
3 proximity sensors 53 and 54 detect upper and lower
permissible limits of particulate material in body 31~
and meter~g pumps (not shown) are provided for metering
the flow of particulate material and fluid material to
hopper 46 and spray head 45. Means (not shown) are also
provided or producing a visual display of the said flow
37,211-F -12-
2 ~ 5
-13-
rate, weight of material removed, a~d levels to enable
the dosage applied to the particulate material to be
accurately moni~ored and controlled.
r~hen the particulate material is seeds, the
seeds may then be planted in soil or ?otting medium,
e.g., in a greenhouse or in the field and under ambient
normal growth conditions the seeds develop into plants
which flower and develop seeds.
As used herein the term "plant" include~ seed
capable of being germinated into a whole fertile plant;
plant cells; plant protoplasts; plant cell or tisque
cultures from which a plant can be regenerated; plant
calli; plant clumps: and plant cells that are intact in
a plant or parts of a plant, 3uch as flowers, kernels,
ear~, cob~, lea~e~, husks, 3talks, and similar parts or
tissues.
37,211-F -13-
