Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Containers For Granular Or Pulverulent Material
The invention relates generally to the filling of
containers with granular or powdered materials, in
particular with finely-divided solids with a high air
content, as well as to features of the container itself.
This application is divided from and comprises the
disclosure of Canadian Patent Application 2,452,775, filed
July 9, 2002. Consequently the expression "the invention"
and the like, as used herein, is not restricted to subject
matter specifically claimed in this divided application,
but may encompass subject matter also described but not
claimed.
The handling of pourable finely-divided solids having
a high air content and low pour density such as, for
example, finely-divided silica, poses various problems.
Producers as well as final consumers are faced with the
fact that these materials raise dust even in the slightest
air convection. The formation of dust must be avoided to
protect the personnel dealing with the product from
possible damage to their health by breathing in the dust.
In addition, the low pour-density increases transportation
costs, because the ratio of container weight to filling
weight is high and a correspondingly large amount of
packaging material is required.
Owing to its three-dimensional spatial branch
structure, finely-divided silica is a product having a very
Iow compacted bulk density of about 40 to 50 g/l. Owing to
its fine structure, finely-divided silica is capable of
binding a very large amount of gas, for example air, so the
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product is put into a quasi-fluid state of about 20 to 30
g/l.
Spontaneous escape of this removable air content takes
place only very slowly and incompletely. The dust problem
is also increased in this fluid state because the mobility
of the finely-divided silica is extremely high.
Pourable finely-divided solids with a high air content
and very low pour-density are therefore introduced into
air-permeable bags predominantly by means of an externally
applied vacuum. The duration of filling increases as the
air content increases.
The bags typically consist of three to four plies of
paper, and one ply of the paper may additionally be
laminated with polyethylene as a barrier against
penetrating moisture. To achieve the desired air
permeability during the filling process, all plies are
microperforated. This has the effect that the product is
compressed as it is introduced into the bag and its filling
density increases relative to the natural pour density.
It also is possible to carry out preliminary
deaeration using special press rollers, but this can always
give rise to structural damage which may adversely affect
the properties of the solids in use.
The higher proportion of the product in the container
weight reduces transportation costs, but this saving is
offset by additional expenditure for procuring the special
container and the necessary filling devices.
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A method and a receptacle for repeated filling with
and emptying of pourable product having a low pouring
density is known from EP 773,159. The woven fabric
receptacle described therein, the so-called big bag or also
super bag, consists of flexible air-permeable woven fabric,
preferably a single or multiple ply of plastic woven fabric
with at least one inlet. This woven fabric receptacle also
is filled using vacuum filling systems. A vacuum is applied
to the woven fabric receptacle, and the product is
aspirated through the open inlet into the woven fabric
receptacle until a predetermined filling weight is
achieved. The issuing gas is distributed over the entire
surface of the woven fabric receptacle. During the filling
process, the product is reversibly compacted, as when being
poured into bags, without its structure being destroyed in
the process.
DE-A-198 39 106 describes flexible large containers
for finely-divided solids having a high air content for
repeated filling using vacuum filling systems, which
consist of at least two superimposed plies, an inner ply
consisting of uncoated air-permeable woven fabric and an
outer ply being dustproof and being coated with a moisture
barrier and these plies being mutually connected by a
special seam in such a way that the container may only be
aerated through it.
With this design of containers, in particular the
increase in moisture in the filling product during storage
in the large container could be reduced.
As the air no longer is able to escape over the entire
surface of the woven fabric receptacle, however, a drawback
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is that the period of time required to reach a
predetermined pouring density is considerably extended, and
the filling capacity therefore reduced. To compensate for
this, DE-A-198 39 106 describes a particular process for
filling this large container, with which the filling
material is subjected to preliminary deaeration prior to
filling, and a further deaeration via the seams of the
fabric is carried out during filling. The preliminary
deaeration and therefore partial compaction of the filling
product are also effected by the application of vacuum.
A drawback of the process described in DE-A-198 39 106
is the extremely high expenditure on apparatus, as vacuum
systems are required for both preliminary compaction and
filling of the large container. Despite this expenditure,
the filling capacity is still too low, so the process
described in DE-A-198 39 106 is uneconomical overall.
The invention provides apparatus for filling a
container with granular, powdered or finely-divided solids
having a high air content; with which a high filling
capacity with adequate compression of the solids to be
poured may be achieved with low expenditure on apparatus
and therefore low capital outlay. The apparatus can
comprise a feed nozzle for introduction of the solids into
a feed orifice of the container under positive pressure,
the feed nozzle comprising a flexible sealing skin which
provides dust-free pressure filling of the container, and
the container being surrounded by a two-part or multi-part
cage which is gas-permeable.
The invention also relates to a method for filling
containers, in particular with finely-divided solids having
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a high air content, by arranging an air-permeable container
in an apparatus according to the invention, air-tight
connection of the container to the feed nozzle, filling of
the container under pressure, and removal of the filled
container.
Finely-divided solids having a high air content may be
poured with adequate compression of the solids in high
capacities using the apparatus and method according to the
invention, without high expenditure on apparatus. In
particular, finely-divided granular powdered solids having
a high air content may be pyrogenic oxides, precipitated
oxides, carbon blacks and modifications thereof.
In particular, with pneumatic conveyance of the
filling product, the resultant pressure is sufficient to
achieve appropriate filling of the container. According to
a preferred embodiment of the invention, the apparatus has
a special feed nozzle which is equipped with a flexible
sealing skin and therefore allows dust-free pressure
filling. The feed nozzle may be deformable and may
therefore allow the filling of containers of various sizes.
The cage, which is an important component of the
apparatus according to the invention has to withstand, in
particular, the pressure required. At the same time, the
cage gives the container adequate support during the
filling process, to ensure that the container withstands
the pressure applied and keeps its shape during the filling
process.
Containers of a wide variety of shapes and of various
materials may be filled in the apparatus according to the
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invention. The materials may be: air-permeable plastic
woven fabric, preferably polypropylene woven fabric,
plastic woven fabric, textile woven fabric, cardboard,
paper, paper plastic woven material, plastic non-woven
fabric, textile non-woven fabric or composites of the
aforementioned materials. The filling pressure is generally
0 to 8 bar, preferably 0 to 2 bar, and particularly
preferably 0.2 to 1.2 bar.
The containers employed in the apparatus and method
according to the invention may be of any conventional
shapes and materials. For example, the containers may have
a base area selected from a group consisting of polygon,
circle, semicircle, ellipse, trapezium, triangle, rhombus,
square and rectangle or a star-shaped base area. The
containers may also have the shape of a hood, of assembled
pockets or the shape of a tied-up bag. To ensure safe
handling even during pressure filling, however, it is
advantageous if, during the filling process, the cage
contacts the container to be filled, as uniformly and
snugly as possible. It is therefore expedient if the cage
substantially corresponds to the shape of the container.
Additional fittings in the cage allow adaptation to the
respective container to be filled.
Owing to the excess pressure prevailing in the
interior of the container, the air is carried off over the
surface of the container. As the excess pressure is able to
escape, compression of the filling product is also
achieved. To enable the excess pressure to escape as
rapidly as possible from the container, in particular in
the case of a snugly fitting cage, it is expedient if the
cage itself is also gas-permeable. The cage may have walls
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with openings or with adequate porosity. This may be
achieved, for example, by openings in the cage walls. It is
particularly advantageous if the cage walls are produced
from a material selected from perforated plate, mesh or
netting, woven fabric or sintered material or a mesh
material, because this allows high gas permeability with
adequate stability to ensure that the container does not
explode even under high filling pressures. The cage may be
in several parts, preferably two parts. The cage may have a
bottom and may be designed without a bottom. Preferably,
the cage has no bottom.
According to a preferred embodiment of the apparatus
according to the invention, the cage may be in two or more
parts and the apparatus comprises additional devices with
which the two parts of the cage may be separated from one
another and may be driven apart manually or automatically,
preferably electro-pneumatically, to release the filled
container. In particular in the case of cage shapes with a
polygonal base area, it is expedient if the cage can be
separated along a diagonal as~this prevents damage to the
container.
According to a particularly preferred embodiment of
the present invention; the cage has no bottom, in other
words the cage is open at the bottom. This embodiment
allows particularly simple management of the filling
process. After the two-part cage has been closed and the
two parts have been connected to one another, the actual
filling process can-begin. For example, the container can
then be positioned directly on a plate or a pallet, the
feed nozzle can then be introduced into the feed orifice of
the container and can be connected in an airtight manner to
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the container. On completion of the filling process, the
two cage wedges can then be separated from one another and
driven apart to release the filled container. As the filled
container is then standing on a plate or pallet, it can
easily be removed by a transportation device.
In another aspect the invention also contemplates a
flexible container for finely-divided solids for repeated
filling and draining, characterized in that it consists of
at least two plies, one above the other, wherein one ply
consists of an air-permeable supporting material that is
preferably non-coated and the other ply consists of a
filter material.
According to one embodiment, the air-permeable,
supporting material can be~arranged on the outside and
filter material on the inside. However, other combinations
of the plies, from the inside toward the outside, are
possible, wherein the combination of supporting and
filtering element of the container is present. The
material used for each ply can be commercially available
material.
The container can be designed for optional amounts of
finely-divided filler materials. The container preferably
can be used for amounts up to 1,200 kg. In contrast,
containers according to prior art could only accommodate
filling amounts of 90 to 100 kg.
The container permits a dust-free filling through
compacting on the inside of the container, in particular
using the apparatus according to the invention, wherein
clearly higher bulk weights can be achieved.
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The finely-divided material can be drained from the
container through a preceding fluidization and simultaneous
conveying. For this, known drainage devices can be used.
Another embodiment is a corrugated-cardboard container
(carton) for finely-divided solids, which can be ventilated.
One side of the container consists of a highly air-permeable
paper, and the inside undulations) as well as the other sides
and intermediate plies consist of non air-permeable standard
corrugated cardboard with microperforation.
Optional combinations of the outer plies, the inner plies
and the intermediate plies are possible, wherein the container
(corrugated cardboard container) has a supporting as well as
filtering design.
This results in the following advantages as compared to
the known technology:
The highly air-permeable inner ply acts as a filter for the
product and permits the air to escape;
The outer ply and the intermediate ply (plies) and the
undulations) absorb the forces, but permit the air to escape.
As a result of this configuration, air is moved quickly through
the walls and the product can be highly compacted inside the
container with considerably higher filling weights than is
possible with known systems (up to 1,200 kg as compared to the
known 90-100 kg, depending on the product type).
The invention will now be described in further detail with
reference to the accompanying drawings, in which:
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Figure 1 is a side view of a preferred embodiment of the
present invention;
Figure 2 is a plan view of the embodiment according to Figure 1
with opened cage;
Figure 3 shows schematically a representation of a container
according to the invention;
Figure 4 shows the drain of Figure 3 in schematic detail;
Figure 5 shows a schematic representation of a corrugated
cardboard container according to the invention.
As shown in the Figures, a preferred embodiment of the
invention comprises a framework 1 with two rails 2 at the top,
along which the two halves 3a and 3b of the cage 3 which may be
moved by conventional drive devices.
In the embodiment shown in Figures 1 and 2, the cage has a
square base area and is divided along the diagonal into the two
halves 3a and 3b. This ensures that two halves easily can be
separated from the filled container, even when the container
has been pressed against the cage owing to a high filling
pressure.
The cage also has two half shells 4a and 4b which surround
the feed nozzle (not shown) when closed.
As shown in Figure 2, the cage 3 is open at the bottom and
the container is positioned on a pallet or plate during the
filling process. It also is advantageous, as shown in the
drawings, if the filling nozzle is arranged symmetrically with
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respect to the frame 1, so a cage half 3a may be removed
further from the pallet or plate 5 to allow easy access, for
example, for a transportation device for removing the filled
container.
A container according to the invention is shown
schematically in Figure. 3.
On the one hand, a container 6 according to Figure 3
consists of two plies, namely a supporting, air-permeable outer
material 7 (PP woven ribbon material with a weight of 75 to 300
g/m3) .
The material is not coated so that air can pass through.
This outer layer is supporting as well as carrying for product
amounts up to 1,200 kg.
On the other hand, a second ply, the inner ply 8
(inliner), consists of a filter material (e. g. HDPE nonwoven
TyvekT"' by DuPont, which holds back the finely-divided product,
but permits the air escaping from the product to pass through.
The drain 9 is shown schematically in Figure 4A. The drain
has a conical design and is thus particularly suitable for a
special draining apparatus according to EP 761,566. Sticky
tapes 10 and 11 are provided, and Figures 4B and 4C are a side
view and a view from above, respectively, of the tape 11 which
is equipped with a D-ring.
Another container according to the invention is shown
schematically in Figure 5, with highly permeable paper 12 on
the product side, microperforate undulation 13, and non-porous
paper 14.
