EP0628351A1 - Method and device for separating a bulk material - Google Patents

Abstract

During the separation of bulk material into at least two fractions with the use of a vibratory table (1) onto which the bulk material is put, very light and/or laminar particles with comparatively high-grade purity can be separated owing to the fact that the fraction which can be brought by vibration to the surface of the bulk material is drawn off upwards in the area of the discharge edge (10) of the vibratory table (1) by means of a suction nozzle (19) from the surface of the bulk-material mat accommodated on the vibratory table (1) and/or crossing the discharge edge (10), and that the remainder is discharged via the discharge edge (10). <IMAGE>

Description

According to a first concept of the invention, the invention relates to a method for separating a bulk material into at least two fractions according to the preamble of claim 1 and, according to a further concept of the invention, relates to a device for carrying out this method according to the preamble of claim 7.

The known arrangements for separating a bulk material flow into two fractions (eg DE-U 89 09 665 ) work with fluidizing the light material over an obliquely arranged vibrating screen, over the upper discharge edge of which the heavy parts are thrown off and over the lower edge of which the fluidized light material flows off. Flat areas behave in these so-called counterflow sifters Particles, such as film residues, shells, etc., as well as non-flat particles of the same weight. Deposition of flat particles is therefore not possible without major losses of other material. The same applies when it comes to separating only light particles.

Proceeding from this, it is therefore the object of the present invention to be able to use simple and inexpensive means to separate flat and / or comparatively light particles with a comparatively high type purity.

This object is achieved procedurally by the characterizing part of claim 1 and device-wise by the characterizing part of claim 7.

The vibrating movement of the vibrating table results in a layering of the bulk material, whereby the particle weight decreases from bottom to top. Flat particles are also concentrated in the upper area of the bulk material mat. Depending on the position and / or suction effect of the proboscis, a more or less thick surface layer can be removed. With a suction effect that extends far beyond the discharge edge, an additional counterflow sifter effect can advantageously also be achieved. The measures according to the invention therefore allow a high degree of variation with regard to the composition of the fraction which can be sucked off by means of the suction nozzle and thus a simple possibility of adapting to the desired circumstances of the individual case.

The bulk material mat accommodated on the vibrating table can expediently be ventilated from below, the air throughput being so low that nothing is suspended. For this purpose, the vibrating table is expediently designed as a vibrating screen which is arranged in a housing which is connected below the vibrating screen to an air supply duct and above the vibrating screen to an exhaust air channel. The ventilation of the bulk material mat supports the segregation caused by the vibrating movements of the vibrating table, in particular with regard to flat particles, such as film residues, trays, etc. The flat particles therefore reach the top relatively quickly. Because there is no swirling, i.e. nothing is suspended, however, it is ensured that the flat position of the flat particles, which is brought about as a result of the vibratory movements of the vibrating table, is maintained, so that the air flowing through from below is offered a comparatively large contact surface, which results in a large amount of buoyancy, so that this flat surface Particles are concentrated in the same way as particularly light particles in the upper layers of the bulk material mat.

The air throughput through the vibrating screen forming the vibrating table can expediently be in the range between 0.2 to 0.75 of the air throughput of a comparable counterflow classifier. This ensures that the undesired formation of a fluidized bed does not occur, so that nothing flows away, but can be sucked off by means of the suction nozzle.

A further measure, which is preferred in many cases, can be that the bulk material placed on the vibrating table is previously subjected to a heavy part reading. The previous heavy part reading not only results in an additional heavy part fraction, but also advantageously enables particularly high efficiency in the subsequent separation of the particularly light and / or flat particles. In some cases, it may be expedient to provide suction in the area of the outlet of the heavy part fraction, by means of which film residues etc. carried along by the heavy parts can be removed.

For this purpose, the feeding device assigned to the vibrating table can simply be designed as a light goods outlet of an upstream counterflow classifier, which has a vibrating sieve which can be driven in opposite directions to the vibrating table and through which air flows from bottom to top, which is arranged so as to rise from the light goods outlet to its opposite discharge edge and can be loaded with bulk material. These measures result in a two-stage device that is characterized by a very high degree of compactness.

The suction nozzle can advantageously have a telescopically extendable and adjustable inlet connection. Likewise, the suction nozzle can expediently have an entrance area which is adjustable in the transport direction of the vibrating table exhibit. This allows the suction depth and / or the suction position to be individually adjusted in a simple manner.

To further refine the suction effect of the proboscis, an adjustable false air inlet can be assigned to it.

Another expedient measure can consist in the fact that the vibrating table is arranged so as to rise to its discharge edge. This allows the dwell time of the bulk material on the vibrating table and thus the segregation that can be achieved with it to be regulated.

Further advantageous refinements and expedient further developments of the superordinate measures are specified in the remaining subclaims and can be found in the example description below.

• Figur 1
  einen Längsschnitt durch eine einstufige erfindungsgemäße Anordnung in schematischer Darstellung und
• Figur 2
  einen Längsschnitt durch eine zweistufige erfindungsgemäße Anordnung in schematischer Darstellung.

Two preferred exemplary embodiments of the invention are explained in more detail below with reference to the drawing.
Show here:

• Figure 1
  a longitudinal section through a single-stage arrangement according to the invention in a schematic representation and
• Figure 2
  a longitudinal section through a two-stage arrangement according to the invention in a schematic representation.

The single-stage separating device on which FIG. 1 is based can be used, for example, for separating film residues from compost or from trays from regrind or from dusts from granules etc. For this purpose, a vibration table 1 connected to a vibration drive is provided. The oscillating drive consists of an eccentric shaft 3 which can be driven by means of a motor 2 and which is connected via a push rod 4 to a box 5 which is made up by the oscillating table 1 and which is arranged resiliently, as indicated by a spring 6. The vibrating box 5 forms the middle part of a housing, the lower part 7 and the upper part 8 are connected via bellows 9 to the oscillating box 5 arranged therebetween.

The table edge of the vibrating table 1 shown on the right in the example shown forms a discharge edge 10, via which the material conveyed by the oscillating movement is thrown off. For this purpose, sufficient free space is provided above the discharge edge 10, which opens into a chute 11 which functions as a good outlet and is attached to the vibrating box 5. The bulk material to be treated is thrown onto the vibrating table 1 in the area of the table edge removed from the discharge edge 10. The loading device provided for this purpose consists in the example shown of a chute 12 attached to the vibrating box 5, into which a stationary feed funnel 13 opens, which here is acted upon by a conveyor belt 14 with the bulk material to be treated. The bulk material is distributed over the entire width of the vibrating table 1 by means of the vibrating chute 12.

The bulk material applied to the vibrating table 1 practically forms a bulk material mat covering the vibrating table 1, within which separation takes place as a result of the vibration movements of the vibrating table 1. The heavier particles are concentrated in the lower layers, the lighter and flat particles in the upper layers. The flat particles are due to the vibration movements of the vibrating table 1 in a practically table-parallel flat position. The dwell time of the bulk material on the vibrating table 1 can be regulated by its inclination. For this purpose, the vibrating table 1 is expediently arranged in such a way that its inclination with respect to the discharge edge 10 can be adjusted, as indicated in FIG. 1 by a double arrow. For this purpose, the vibrating table 1 is expediently pivoted about an axis near the discharge edge.

In order to promote the separation of the bulk material caused by the vibration of the vibrating table 1, the bulk material mat received on the vibrating table 1 is ventilated from below, so that there is an air flow directed from the bottom upwards. For this purpose, the vibrating table 1 is designed as an air-permeable sieve table. This consists, in a manner known per se, of a lower perforated plate 15 which acts as a flow mask and which is spanned by a fabric 16. The air is introduced into the lower housing part 7 via a supply air duct 17 or alternatively generated by a fan arranged in the lower housing part 7 and from the upper part of the housing via an exhaust air duct 18, to which a fine dust separator can be assigned 8 derived. The air throughput is metered in such a way that the bulk material accommodated on the vibrating table 1 is not fluidized, that is to say that nothing is suspended. The lighter and flat particles are therefore not whirled up, but simply pushed upwards, so that concentration takes place in the upper layers of the bulk material mat. Since there is no fluidization, the flat particles remain in the flat position caused by the vibration of the vibrating table 1, which results in a large contact surface for the air. The flat particles are therefore pressed up particularly well and concentrated on the surface of the bulk material mat received on the vibrating table 1. Fine-grained material can fall through the sieve. This can expediently be collected and discharged via a slide provided in the lower housing part 7.

The particles concentrated as a result of the vibratory movements of the vibrating table 1 and, if appropriate, the air throughput on the surface and / or the upper region of the bulk material mat received on the vibrating table 1 are sucked up as the first fraction. The rest is thrown off as a second fraction over the discharge edge 10. For sucking off the first fraction, a suction trunk 19 is provided which extends over the entire width of the vibrating table 1, which is received on the vibrating box 5 and connected to a suction line 20 which can be acted upon by suction. The induced draft is generated by a fan 21. To vary the suction draft, the suction line 20 is provided with an adjustable false air flap 22, via which more or less false air can be tightened. The blower 21 can therefore work with constant power. A separator 23 designed here as a cyclone for separating air and solids is arranged in the suction line 21. The separator 23 is provided with a solids outlet designed as a lock wheel 24, via which the particles sucked off from the top of the bulk material mat can be discharged.

The inlet nozzle 25 of the suction nozzle 19 is adjustable and adjustable in height relative to the vibrating table 1 or the top of the bulk material mat accommodated thereon. For this purpose, the suction nozzle 19 is provided with an inlet nozzle 26 which contains the inlet nozzle 25 and is telescopically retractable and extendable, and is arranged so that it can be locked and locked. A manually operable spindle drive can be provided, for example, for setting the inlet connector 26. A motorized actuation, for example by means of a cylinder-piston unit, would also be conceivable.

Likewise, the position of the inlet nozzle 25 with respect to the discharge edge 10 in the conveying direction of the vibrating table 1 can be adjustable. For this purpose, the end region of the suction nozzle 19 can be arranged to be easily displaceable or pivotable, as is indicated by broken lines. After adjustment, the fixation is carried out, for example, by means of a clamping device. The suction nozzle 19 with its inlet nozzle 25 is always in a front region in the transport direction of the vibrating table 1, which contains the discharge edge 10 or is adjacent to it: In some cases, for example when extracting shells, it may be expedient if the suction nozzle 19 with its inlet nozzle 25 is located in the quarter of the vibrating table 1 near the discharge edge. In the example shown, the suction nozzle 19 is arranged such that its central axis is distant from the discharge edge 10 by the width of the inlet nozzle 25. In other cases, for example when vacuuming film residues, it can be advantageous if the suction nozzle 19 extends at least partially beyond the discharge edge 10 with its inlet nozzle 25, for example is set so that the axis of the inlet nozzle 25 is aligned with the discharge edge 10. As a result, a certain counterflow classifier effect can be achieved with the material which has already passed the discharge edge 10 by means of the air sucked in via the chute connected to the discharge edge, and thus improve the readout even further.

By adjusting the distance of the inlet nozzle 25 from the top of the bulk material mat, by adjusting the suction by appropriate metering of the false air drawn in and by appropriately positioning the inlet nozzle 25, the suction effect of the suction nozzle 19 and, accordingly, the desired suction depth can be precisely adjusted. This makes it possible to precisely adjust the composition of the first fraction sucked off by means of the suction nozzle 19. Readjustment can be carried out on the basis of a visual observation of the material discharged via the lock wheel 24. However, it would also be conceivable for this readjustment by automatic Monitoring of the discharged material.

In the two-stage arrangement on which FIG. 2 is based, a separation device of the type described above is preceded by a device for reading heavy parts which forms the first stage. This makes it possible to read from the bulk material to be treated, for example compost, heavy parts such as stones, broken glass, etc., whereby the separation process assigned to the second stage can be optimized. The basic construction of the separating device forming the second stage corresponds to the device described above. We therefore do not repeat the detailed description. In the following, the special features of the arrangement according to FIG. 2 are primarily dealt with, the same reference numerals as above being used for the same parts with respect to the separating device forming the second stage.

The device for the heavy part reading forming the first stage is designed as a counterflow classifier known per se. This consists of a vibrating screen 29 arranged in a vibrating box 28 connected to a vibrating drive, which is formed by a flow mask formed by a perforated plate and a fabric spanning it. Arranged above the vibrating screen 28 is a material inlet 29, which here is formed by a slide received on the vibrating box 27 and a feed pipe opening into the latter, into which the material to be treated is thrown, as indicated by a conveyor belt is. The vibrating screen 28 is loaded with bulk material over its entire width by the material feed 29.

The box 27 of the first stage receiving the vibrating screen 28 and the box 5 of the second stage receiving the vibrating table 1 are arranged one behind the other in the longitudinal direction and can be driven by means of associated tie rods 4, 4a via a common eccentric shaft 3. For this purpose, this is provided with eccentrics so offset in the circumferential direction that the boxes 5 and 27 oscillate horizontally in opposite directions, which facilitates mass balance. The eccentricities of the eccentrics and, accordingly, the amplitudes of the vibrations of the boxes 5 and 27 caused thereby are adapted to the respective separation task. The oscillating box 27 is connected via a bellows 9 to an associated lower housing part 30, to which a supply air duct 31 is connected or in which a blower is installed. On the exhaust air side, an upper housing part 32 extending over both boxes 5, 27 is provided, which has bellows 9 connected to the respective assigned box inlet connection and is connected to a common exhaust air duct 18a, to which a dust separator can be assigned. Of course, it would also be conceivable to provide separate upper housing parts and exhaust air ducts. The common drive device is located in the area between the lower housing parts 7 and 30, which are indented chamber-shaped for this purpose. The oscillating springs 6, 6a assigned to the boxes 5, 27 are accordingly located in the region of the box sides facing away from one another.

The edge of the vibrating screen 28 facing away from the vibrating table 1 functions as its discharge edge 33, from which the vibrating screen 28 is arranged with a slope. The angle of inclination can be adjustable, as indicated by a double arrow. An adjustable flap 34 is arranged above the discharge edge 33, by means of which the false air drawn in via the good outlet 35 assigned to the discharge edge 33 can be adjusted.

The air supplied by means of the supply air duct 31 is metered in such a way that, in contrast to the vibrating table 1, the bulk material received on the vibrating screen 28 is fluidized. The entire bulk material is whirled up with the exception of the heavy parts remaining on the vibrating screen 28. The heavy parts are conveyed to the discharge edge 33 by vibratory transport and thrown into the good outlet 35, which accordingly acts as a heavy part outlet. The whirled up light material swims in the direction of the gradient of the vibrating screen 28 over its lower edge and reaches the vibrating table 1 here via a guide device 36 bridging the distance between the adjacent edges of the vibrating screen 28 and the vibrating table 1. The light material fraction floating off the vibrating screen 28 forms here accordingly the input material for the second stage, in which the particularly light and / or similarly behaving, flat particles are sucked upwards through the suction nozzle 19 assigned to the discharge edge 10. In some cases, it may be expedient to also preferably set the discharge edge 33 of the vibrating screen 28 diametrically opposite the discharge edge 10 Assign suction probes for suction of light particles entrained by the heavy goods. In cases of this type, the flap 34 can be omitted. The material sucked off in the region of the discharge edge 33 can either be fed to the separator 23 or preferably to the vibrating table 1 for further separation.

In the example shown, the guide device 36 is simply designed as a slide attached to a window arranged above the floating edge 37 of the vibrating screen 28, which passes through a window of the adjacent wall of the box 5 and ends above the area of the vibrating table 1 that is remote from the throw-off edge. In cases of this type, there is of course a pressure equalization between the spaces above the vibrating screen 28 and vibrating table 1. To prevent such pressure equalization, a lock wheel could be provided as a guide device in connection with separate upper housing parts.

The vibrating screen 28 and the vibrating table 1 are of the same size in the example shown. However, the air throughput through the vibrating table 1 is significantly lower than the air throughput through the vibrating screen 28. The air throughput through the vibrating table 1 is 0.2 to 0.75 of the air throughput through the vibrating screen 28, depending on the composition of the material to be treated, in contrast to this fluidization of the light goods takes place at the downstream stage. In the second stage, the particularly light and / or concentrated at the top of the bulk material mass lying on the vibrating table 1 flat particles are sucked up by means of the suction nozzle 19 and separated in the separator 23 arranged upstream of the blower 21.

Claims (14)

Method for separating a bulk material into at least two fractions using at least one vibrating table (1) to which the bulk material is applied and which has at least one discharge edge (10) over which an assigned fraction is thrown off, characterized in that the vibrations on the surface of the bulk material fraction that can be brought in the region of a discharge edge (10) of the vibrating table (1) is sucked upwards and the rest is thrown off over the discharge edge (10). A method according to claim 1, characterized in that the fraction which can be brought to the surface of the bulk material by vibration is essentially sucked off at least partially before the discharge edge (10) of the vibrating screen is reached. Method according to one of the preceding claims, characterized in that the suction takes place at least partially in the manner of a countercurrent sifting of the material which has already passed over the discharge edge (10). Method according to one of the preceding claims, characterized in that the bulk material mat received on the vibrating table (1) is ventilated from below, the air flow is so low that nothing goes into suspension. Method according to one of the preceding claims, characterized in that the bulk material applied to the vibrating table (1) is previously subjected to a heavy part reading, which is preferably carried out by fluidization by means of air passed through from below and vibratory conveying of the heavy goods. A method according to claim 5, characterized in that suction is also carried out in the region of the heavy material discharge edge (33). Device for carrying out the method according to at least one of the preceding claims, with at least one oscillating table (1) connected to an oscillating drive (2, 3), which has at least one discharge edge (10) and which has at least one loading device (12) removed from the discharge edge (10) or 36), characterized in that in the area of at least one discharge edge (10) at least one suction nozzle (19) arranged above the oscillating table (1) and provided with suction is provided. Apparatus according to claim 7, characterized in that the suction nozzle (19), which can be lowered onto the oscillating table (1) and is adjustable relative to the latter, preferably has an telescopic, extendable and adjustable inlet connection (26). Apparatus according to claims 7 to 8, characterized in that an adjustable false air inlet (22) is assigned to the suction nozzle (19). Device according to one of the preceding claims 7 to 9, characterized in that the suction nozzle (19) can be adjusted with respect to the associated discharge edge (10) in the feed direction of the vibrating table (1), preferably has a pivotable entrance area. Device according to one of the preceding claims 7 to 10, characterized in that the suction nozzle (19) is connected to a separator (23) which is connected to an evacuation fan (21). Device according to one of the preceding claims 7 to 11, characterized in that the vibrating table (1) is designed as an air-permeable vibrating screen which is arranged in the middle part of a housing, the lower part (7) of which is connected to a supply air source (17) and the upper part (8 or . 32) is connected to an exhaust air duct (18 or 18a) and that the air throughput through the vibrating screen forming the vibrating table (1) is preferably in the range between 0.2 to 0.75 of the air throughput of a counterflow classifier of comparable size. Device according to one of the preceding claims 7 to 12, characterized in that the loading device assigned to the vibrating table (1), the inclination of which can preferably be adjusted with respect to its discharge edge (10), as a light goods outlet of a preceding one Counterflow sifter is formed which has an air-permeable vibrating sieve (28) which can be driven in the opposite direction to the vibrating table (1) and which rises from its floating edge (37) to its opposite discharge edge (33) and can be loaded with bulk material, the vibrating sieve (28) and the oscillating table (1) is preferably arranged one behind the other in the longitudinal direction and is connected to one another by means of a guide device (36) bridging the distance, preferably designed as a slide. Apparatus according to claim 13, characterized in that at least one preferably adjustable suction nozzle (19) is associated with the discharge edge (10) of the oscillating table (1) and the discharge edge (33) of the upstream counterflow classifier.

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