EP0828570B1

EP0828570B1 - A device for separating material

Info

Publication number: EP0828570B1
Application number: EP96917767A
Authority: EP
Inventors: Rolf Linder
Original assignee: Spiral Tech I Borlange AB
Current assignee: Spiral Tech I Borlange AB
Priority date: 1995-06-02
Filing date: 1996-05-31
Publication date: 2001-08-16
Anticipated expiration: 2016-05-31
Also published as: NO314620B1; NO975478D0; SE9502014D0; SE515353C2; EP0828570A1; NO975478L; ATE204213T1; SE9502014L; DK0828570T3; DE69614530T2; DE69614530D1; WO1996038237A1

Abstract

A device for separating material comprises a container (2) provided with a plurality of holes (1) and adapted to receive the material to be separated and a member (3) for feeding the material in the container (2). The device is characterized in that the feeding member (3) is arranged to pass over the holes (1) with parts thereof during the feeding and by that to bring a first fraction of the material to pass out through the holes (1) and a second fraction to be continuously fed in the container (2). The device may be used for screening of materials consisting of several fractions in general and in particular of material comprising plastic in the form of plastic bags and compostable material.

Description

FIELD OF THE INVENTION AND PRIOR ART

This invention relates to a device for separating material according to the preamble of appended claim 1.

In order to exemplify but not in any way restrict the invention the particular case of separating compostable material from plastic material in connection with handling waste material, such as household garbage placed in plastic bags, will be described hereinafter. However, it has already in the introduction to be pointed out that the device according to the invention is very well suited to be used also for separating other types of material. The device according to the invention is particularly suited for separating material in which one of the fractions to be separated from each other is tough, continuous and/or sticky and by that has a tendency to obstruct the prior art devices used until now for this purpose.

Such devices of conventional type have preferably until now been drum sieves having considerable dimensions. These are not seldom both clumsy and heavy, so that considerable efforts are required to move and install these to and at the location where they are going to be used, and they are also expensive.

FR-A-2 539 337 describes a device for separating material comprising a container provided with a plurality of holes and for receiving the material to be separated and a member with the shape of a screw for feeding the material in the container. The feeding member is adapted to pass over the holes in the perforated part of the container through parts thereof during the feeding and thereby to cause a first fraction of the material to pass out through the holes and a second fraction to be continuously fed in the container. This device is intended to separate foreign particles from grapes in connection with grape harvest by feeding the mixture of the grapes and the foreign particles by a screw over the holes in a container 1 for making the foreign particles pass through the holes. It is mentioned that a material being removed in this way is not damaged, but the separation is obviously only obtained by the gravitation, the presence of the holes and the cross section thereof being smaller than that of the grapes, by which the foreign material may fall through the holes. Even if the device according to FR-A-2 539 337 is well suited for separation of exactly foreign particles from grapes in connection with grape harvest, grape problems would arise would it be used for separation of material in which any of the fractions to be separated from each other is tough and/or has a sticky consistency. Such a separation would in the practice not be possible through that device, but the material in question would have the tendency to pass the holes, and plugging or obstructing of the holes through which one of the fractions to be separated from each other is intended to pass would easily arise. A consequence thereof would be a requirement of frequent cleaning of the device, which is very disadvantageous, since such cleaning is time consuming, requires considerable labour and is not seldom apprehended as unpleasant for the person forced to do this, since such materials have often an unpleasant composition and emit odours being hard to stand.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a device which find a remedy to the inconveniences mentioned above of the device according to FR-A-2 539 337and enables also an efficient separation of materials with a tough and/or sticky consistency from each other while minimizing the frequency of interruptions of the operation necessary as a consequence of need of cleaning.

This object is according to the invention obtained by providing such a device, in which the feeding device is arranged to pass closely over the holes through parts thereof and thereby in co-operation with the edges of the holes give rise to shearing of the material between the hole edges and the feeding member, and by providing the feeding member designed as a screw with a central longitudinal cavity.

The features of the characterizing part of claim 1 co-operates in a very advantageous way for obtaining the object of the invention. By the fact that the feeding screw is adapted to pass closely over the holes and thereby in co-operation with the edges of the holes give rise to shearing of the material between the hole edges and the screw a disintegration of the material is also obtained in connection with the separation, but such a shearing action primarily counteracts plugging or cogging of the holes. The separation performance of the device is further improved by connecting this shearing action with the feature that the feeding screw is provided with a central longitudinal cavity, through which a very good stirring effect and redistribution of the material to be separated is obtained, which is favourable for the very separation as well as the subsequent treatment of any of the fractions, for example a compostable material.

According to a further embodiment of the device according to the invention the feeding device comprises means adapted to carry material therewith, and then preferably said second fraction, in the rotational movement about the rotation axis of the feeding member and means for carrying material therewith, comprises projections projecting in the feeding direction from the screw-like feeding member.

The projections have the advantage that they by that further contribute to the separation of the material in the respective fractions thereof, which is particularly clear in the case when plastic in the form of plastic bags, oils or the like is separated from compostable material, in which case the plastic is primarily carried along by the projection.

According to a further preferred embodiment of the device according to the invention this comprises an arrangement arranged below the container for transporting said first fraction away, said arrangement comprising a transporting member adapted to also procure a stirring of the first fraction besides transporting this fraction in a certain direction, said transporting member being designed as a screw with a central continuous cavity.

A positive effect in the cases of material handling in which the subsequent treatment of the first fraction is favoured by such a stirring is in this way created. In the case of compostable material the stirring results in an additional supply of oxygen to this material, which promotes a further treatment in a biogas tank. For the rest, thanks to the central continuous cavity the same stirring advantages as already described for the feeding member are obtained.

Further advantages and preferred embodiments of the invention will appear from the following description and the rest of the patent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the appended drawings, below follows a description of an embodiment of the invention cited as an example.

In the drawings:

Fig. 1: is a perspective view of the device according to the invention,
Fig. 2: is a side-elevation view of the device according to the invention,
Fig. 3: is a cross-section view of the device according to the invention, and
Fig. 4: is a partially sectioned view of a portion of the device according to the invention laterally seen.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

A preferred embodiment of the device according to the invention is shown in Fig. 1. This comprises a container 2 provided with a plurality of holes 1 and which is intended to receive material to be separated in the device. The container 2 is also intended to accommodate a member 3 arranged for feeding the material in the container, which appears from the Figures 3 and 4.

The feeding member 3 is arranged to pass over the holes 1 by parts thereof during the feeding and to by that bring a first fraction of the material to pass out through the holes 1 and a second fraction to be fed further in the container 2. The feeding device 3 is arranged to pass closely over the holes 1 through parts thereof and by that through the corporation with the hole edges give rise to shearing of material between the hole edges and the feeding member 3. In the preferred embodiment the feeding member 3 has the shape of a screw, which is driven by a driving device 4, which is arranged at one end of the container and in principle may be of any suitable type, for instance an electric motor. As it appears especially from Fig. 3 the feeding member 3 is provided with a central longitudinal cavity 5. This is of a great importance for achieving stirring of the material in the container 2.

The feeding member 3 further comprises means 6 adapted to carry the material therewith, and 5 preferably the second fraction, in the rotational movement about the rotation axis of the feeding member 3. It appears from Fig. 3 and 4 that the means 6 for carrying material therewith comprises projections projecting in the feeding direction from the screw-like feeding member 3. The projections are preferably elongated and extend in a direction substantially in parallel with the feeding direction, but deviations from such a parallelism are also conceivable within the scope of the invention. The means 6 for carrying material therewith are then preferably designed as pins. It is preferred that at least one such means 6 for carrying material therewith is arranged on each screw turn, which is the case in the preferred embodiment and which has turned out to be very efficient in practise. The length of the means 6 for carrying material therewith may be varied within comparatively broad limits but is in the preferred embodiment, in which especially separation of plastic material in the form of plastics bags from compostable material is intended, in the region of 1-30 cm, preferably 5-15 cm. In a specific embodiment of the invention a length of about 10 cm of the members has led to excellent results. They are of great importance for the material separation, since they preferably pull one of two fractions to be separated along, usually the more gluey and continuous thereof, and by that contributes to an improved separation.

The device comprises further an arrangement 7 located below the container 2 for transporting the first fraction away. It has an opening upwardly for receiving the material falling from the container 2 through the holes 1. The arrangement 7 comprises for the transportation of the fraction so received a transporting member 8 arranged to also cause stirring of the first fraction besides transporting it in a certain direction. In the preferred embodiment the transporting member 8 is designed as a screw having a central continuous cavity 9. Similar to the cavity 5 of the feeding member 3 the cavity 9 of the transporting member 8 contributes to an improved stirring of the material transported therein, which in some cases is of an essential importance for a further treatment of this material as mentioned above.

For optimising the function of the device there are an amount of variables possible to adjust according to the type of material to be separated, the amount of such material, the size of or the size distribution of particular pieces of the material supplied to the device, the type of the subsequent treatment of the fractions separated, the outer conditions (such as for example the temperature), etc. Example of such variables are the length and diameter as well as the inclination of the container 2 and of the feeding member 3. Since especially an increased feeding speed is desired it is favourable that the feeding member and the container are inclined in the longitudinal direction thereof, through which material is brought to pass faster through the device.

Also the size of the holes 1 as well as the design, location and number thereof may preferably be varied according to the particular case. It is then particularly advantageous that the container 2 is formed by a frame 11 and at least a member 12 releasably connected thereto and provided with holes. This makes it possible to replace the member or members provided with holes by members having a different size and/or design of the holes.

With respect to the design of the holes, it has turned out, in particular in the case when plastic material in the form of plastic bags are separated from compostable material, that it is advantageous that the holes have a substantially elongated shape with longitudinal direction thereof in an angle, preferable a substantially right angle, with the longitudinal direction of the feeding member 3. Such an elongated shape of the holes 1 is indicated, even if it is a little bit unclear in Fig. 4. Elongated shape comprises here that the holes extend further in one direction than in another.

The pitch of the feeding member 3, when this has the shape of a screw, and the width of the screw threads are also variables which a man skilled in the art may in a suitable way adjust for the particular case without departing from the idea of the invention thereby. The same is valid for the design of the projections 6 as well as for the speed selected for the passage of the feeding member 3 with parts thereof over the holes 1. When the feeding member 3 has the design of a screw it is appropriate that such a speed variation takes place by adjusting a number of revolutions by which the screw is rotated.

The device is intended to be used in the following way:

Material, which for example in an earlier stage has been excerted to any form of crushing, disintegration or the like so as to give it a shape more suited for separation or so as to a certain extent separate an envelope from the content thereof, as is the case for plastic bags containing compostable material, is fed downwardly to an inlet 10 connected to the container 2 and having a hopper-like design, said inlet being located at one end of the container 2. The material supplied to the container 2 is fed therein by making the feeding member 3, which has the shape of a screw, to rotate by means of the driving device 4. The feeding member 3 co-operates with the hole edges of the hole 1 by passing closely thereover and by that shear material present there. Since one fraction, as in the case of plastic material and compostable material of plastic, is more continuous and/or tougher than the first fraction intended to be separated therefrom, this fraction will not be cut off and fall downwardly through the holes to any larger extent, but it will rather be carried further by the feeding member 3 and also penetrate in between the outer circumference thereof and the container 2 and by that function lubricating between the feeding member 3 and the container 2. Thus, the first fraction falls downwardly through the holes 1, while the second fraction is fed in the feeding direction of the feeding member 3.

The first fraction falls downwardly into an arrangement 7 for transporting it away, wherein the transporting member 8 feeds the first fraction to one end of the arrangement 7 where this fraction is collected, on for example a conveyor belt or in any form of container, and is transported further for additional treatment.

The second fraction fed in the container 2 is also finally fed out of the container, which as the arrangement 7 is open at one end thereof, and is transported further away therefrom in a similar way as the first fraction.

When the device is intended for separating plastic material, preferably in the form of plastic bags, from compostable material, the entire device has preferably a length in the order of 10 m. It is therefore comparatively easy to place on a platform of a lorry and transport to stations where it is intended to in this way separate the content of household garbage and the like.

The device has with respect to the application just described, plastic and compostable material, turned out to be very well suited, and only very small proportions of the plastic material have after the separation been possible to find among the compostable material. An additional considerable advantage of the device with respect to drum sieves and the like according to the prior art, is a very largely reduced need of cleaning required by this device.

Finally, it is to be noted that the device according to the invention not in any way is restricted to the preferred embodiment described above, but many possibilities to modifications thereof will be apparent to a man skilled in the art without departing from the idea of the invention.

Claims

A device for separating material comprising a container (2) provided with a plurality of holes (1) and for receiving the material to be separated and a member (3) for feeding the material in the container (2), said feeding member (3) being adapted to pass over the holes (1) through parts thereof during the feeding and to by that cause a first fraction of the material to pass out through the holes (1) and a second fraction to be continuously fed in the container (2), said feeding member (3) having the shape of a screw, characterized in that the feeding device is arranged to pass closely over the holes (1) through parts thereof and by that in cooperation with the edges of the holes give rise to shearing of the material between the hole edges and the feeding member (3), and that the feeding member (3) designed as a screw is provided with a central longitudinal cavity (5).
A device according to claim 1, characterized in that the feeding device comprises means (6) adapted to carry material therewith, and then preferably said second fraction, in the rotational movement about the rotation axis of the feeding member (3).
A device according to claim 2, characterized in that the means (6) for carrying material therewith comprises projections projecting in the feeding direction from the screw-like feeding member (3).
A device according to any of the preceding claims, characterized in that container (2) is formed by a frame (11) and at least a member (12) provided with holes releasably connected thereto.
A device according to any of the preceding claims, characterized in that the feeding member (3) and the container (2) are inclined in the longitudinal direction thereof.
A device according to any of the preceding claims, characterized in that it comprises an arrangement (3 ) arranged below the container (2) for transporting said first fraction away, said arrangement comprising a transporting member (8) adapted to also procure a stirring of the first fraction besides transporting this fraction in a certain direction.
A device according to claim 6, characterized in that the transporting member (8) is designed as a screw having a central continuous cavity (9).
A device according to any of the preceding claims, characterized in that the holes (1) have an elongated shape and are oriented with the longitudinal direction thereof making an angle, preferably a substantial right angle, with the longitudinal direction of the feeding member (3).
A device according to any of the preceding claims, characterized in that it is intended for separating a material into fractions having different toughness.
A device according to any of the preceding claims, characterized in that the first fraction is mainly constituted by compostable material and a second fraction is mainly constituted by plastic material.