WO2001064359A1

WO2001064359A1 - Separating device for solid particles

Info

Publication number: WO2001064359A1
Application number: PCT/NL2001/000118
Authority: WO
Inventors: Tako Pieter Rinze De Jong; Holger Ulrich Reinhold Kattentidt; Edwin Albert Schokker
Original assignee: Technische Universiteit Delft
Priority date: 2000-03-01
Filing date: 2001-02-12
Publication date: 2001-09-07
Also published as: NL1014535C2; AU2001237815A1

Abstract

The invention relates to a separating device for solid fragments, comprising a conveyor belt for supplying the fragments, at least one sensor for detecting the fragments, and an ejector for dislodging the fragments from the belt. The ejector is embodied as mechanical impulse-transmitting organ operating in dependence on the sensor.

Description

Separating device for solid particles

The invention relates to a separating device for solid fragments, comprising a conveyor belt for supplying the fragments, at least one sensor for detecting the fragments, and an ejector for dislodging the fragments from the belt.

Such a separating device is used in practice for the recovery or for recycling fragments of material. In the recycling technology mixtures of material have to be separated into pure fractions before reuse is possible. As no methods are known for efficiently separating certain kinds of mixtures, sorting is currently often still carried out manually.

There are systems that by means of sensors are capable of detecting fragments on a conveyor belt or a sloping surface, and of subsequently removing them from the fragment stream at the end of said conveyor belt with the aid of an air blast. An example of this is disclosed in US-A-5, 894 , 938. These systems have been developed as alternative for separating the fragments manually. A draw- back of this latter method is that it is labour-intensive and involves high costs. A drawback of the first method is that apart from the fragments to be removed, fragments in the vicinity are also blown away, which causes an impurity in the separation step. A second drawback of this method is that the stream of fragments can only be separated into two fractions.

Other systems are also known wherein fragments are scanned on a conveyor belt and depending on that result, after falling off the belt, during their free fall, are subjected to a separation process by means of an air distributor; see for example, US-A-5 , 305 , 893 and US-A- 5, 908, 117.

It is the object of the invention to provide a separating device by which after detection, the fragments can be selectively removed at a high throughput and in large numbers in various different streams.

To this end the separating device according to the invention is characterized in that the ejector is em- bodied as mechanical impulse-transmitting organ operating in dependence on the sensor. The number of sensor-ejector combinations may optionally be chosen to conform to the desired number of different fragments to be separated.

A very suitable embodiment of the separating de- vice that may be realized at low cost and very simply, is characterized in that the mechanic impulse-transmitting organ is a jolting rod located under the belt, and that a receiving organ is provided above the belt for catching the fragment that has been knocked off the belt by the jolting rod. Advisably, the bottom side of the receiving organ is positioned at a distance above the belt to allow fragments to pass unimpeded underneath.

Preferably an organ is provided for locally producing an underpressure under the belt to limit the vertical divergence of the belt after activation of the impulse-transmitting organ. By this means the fragments can be supplied via the belt at a greater density, i.e. at smaller mutual distances, without compromising the effectiveness of the device. The invention is also embodied in an ejector suitable for use in a separating device as described in the above, and which is embodied to comprise a blow nozzle formed by an outlet pipe for compressed air. Such an outlet pipe with blow nozzle is already in general use in the prior art and acts as air distributor.

In the frame of the invention said ejector is embodied such that a jolting body is provided on the blow nozzle of the outlet pipe, which jolting body comprises a sleeve- like organ that is provided with openings for the escape of air, and in which sleeve-like organ the outlet pipe is at least partially and movably accommodated. The invention will now be explained in more detail by means of a non-limiting exemplary embodiment and with reference to the drawings, which in Figure 1, show an ejector according to the in- vention; in Figure 2, show the working principle of the separating device according to the invention; and in Figures 3, and 4 show a side view and a top view, respectively, of the separating device according to the invention.

Figure 5 shows 25 different fragments that have been processed in the separating device according to the invention. Identical reference numbers used in the figures refer to similar parts.

With reference first to the Figures 3 and 4, a separating device 1 is shown comprising a conveyor belt 2, a sensor 3 (not shown in Figure 4) , and an ejector 4. The ejector 4 is shown in more detail in Figure 1. This ejector 4 is preferably pneumatic, having a valve 5 for compressed air to which an outlet pipe 6 is connected which is provided with a blow nozzle 7. On the outlet pipe 6 a jolting body 8 is provided, which comprises a sleeve- like organ 9 that is provided with openings 10 for the escape of air. The sleeve-like organ 9 surrounds the outlet pipe 6 in such a manner that, when due to activation of the valve 5 compressed air leaves the outlet pipe 6, this is able to escape by lifting the jolting body 8 such that the escape openings 10 successively come free from the outlet pipe 6, thereby cancelling the driving force of the compressed air and subsequently allowing the jolting body 8 to return to its starting position as shown in the figure . As shown both in Figure 3 and Figure 2, the ejector 4 is preferably designed as a mechanical impulse- transmitting organ, as explained just now with reference to Figure 1, which is located under the belt 2. Above the belt, a receptacle 11 is provided for catching and removing the fragment that has been knocked off the belt by the ejector 4. The working of the separating device 1 is illustrated in Figure 2, showing the various consecutive stages involved in the removal of a specific fragment 12 from the belt 2. The removal process begins with the situation shown in the left-hand section of Figure 2. The fragment 12 supplied by the conveyor belt 2, is detected by the sensor 3. The sensor 3 is coupled with the tappet 4, such that when the fragment has arrived more or less at the location of the tappet 4, the same is activated (see the middle section of Figure 2), delivering an upwards directed impulse to the fragment 12. This, together with the velocity of the fragment 12 in the direction of movement of the conveyor belt 2, results in the fragment 12 being knocked off the conveyor belt 2 and landing in the receptacle 11, thereby effectuating a separation from the remaining fragments on the conveyor belt . This latter situation is shown in the right-hand section of Figure 2. How the above-discussed separating device 1 may be supplemented by additional sensor-percussion-organ combinations in order to realize multiple separation of fragments, is obvious to the person skilled in the art.

To further elucidate the effect of the separating device 1 according to the invention, the same was experimentally loaded with an assortment of fragments numbered 1 to 25, as shown in Figure 5. The belt speed was 1 m/s. The results obtained by means of the separating device according to the invention are tabulated in the Table 1 below. The following remarks are relevant.

The experiment shows that an impulse on a particular fragment affects the neighbouring fragments. Therefore there has to be sufficient distance between the fragments, in the longitudinal direction of the belt this distance has to be greater for heavier fragments than for lighter fragments, whereas widthwise this is of little consequence. The minimum distance mentioned in the table from one fragment to neighbouring fragments, is the dis- tance at which an impulse on a fragment does not disturb the neighbouring fragments. By optimizing the type of belt in use, for example, by employing an organ that by means of locally applied underpressure suppresses the vertical movement of the belt, it may be possible to reduce the minimal distance between the fragments. An organ by means of which such a local under-pressure under the belt may be applied, is known to the person skilled in the art and is therefore not illustrated in the figure. Separability is good if after the impulse, the fragments attain sufficient height (minimally 10 cm) . A well-positioned jolt to the fragment provides the lifting fragment with sufficient impetus for landing in a receptacle above the conveyor belt. With heavier tappets than those used in the ex- periment it is possible to apply sufficient impulse also on the heavier fragments to enable them to separate from the stream. In order to improve the separation of larger, heavier fragments, it would also be possible to have a plurality of ejectors applying an impulse.

TABLE 1

Claims

1. A separating device for solid fragments, comprising a conveyor belt for supplying the fragments, at least one sensor for detecting the fragments, and an ejector for dislodging the fragments from the belt, characterized in that the ejector is embodied as mechanical impulse-transmitting organ operating in dependence on the sensor.

2. A separating device according to claim 1, characterized in that the mechanic impulse-transmitting organ is a jolting rod located under the belt, and that a receiving organ is provided above the belt for catching the fragment that has been knocked off the belt by the jolting rod.

3. A separating device according to claim 1 or 2 , characterized in that an organ is provided for locally producing an underpressure under the belt to limit the vertical divergence of the belt after activation of the impulse-transmitting organ.

4. A separating device according to claim 2, characterized in that the bottom side of the receiving organ is positioned at a distance above the belt to allow fragments to pass unimpeded underneath.

5. An ejector suitable for use in a separating device according to one of the preceding claims, compris- ing a blow nozzle formed by an outlet pipe for compressed air, characterized in that a jolting body is provided on the blow nozzle of the outlet pipe, which jolting body comprises a sleeve-like organ that is provided with openings for the escape of air, and in which sleeve-like organ the outlet pipe is at least partially and movably accommodated.