WO1989004722A1 - Process and device for separating heavy admixtures from grain - Google Patents

Abstract

The invention concerns a process and device for separating heavy admixtures from a product stream (20), in particular stones (28) from grain, in which the product stream (20) is fed onto a layering table (3; 3b; 3d) and layered and conveyed in essentially layered form over the inclined, vibrating layering table surface which is traversed by an air current. The heavy admixtures in direct contact with the layering table (3; 3b; 3c) are conveyed upward over the table, separated and conducted away at the upper end of the table. The product stream (20) is fed by means of a feed channel which opens into the region of the upper end of the table and feeds the corn in a stream of maximum surface width into the separating zone for the corn layers (25, 26) located in said region.

Description

 Method and device for reading out heavy admixtures from grain

The invention relates to a method for reading out heavy admixtures, in particular stones made of grain material, in which the material is fed onto a shift table and is guided in a stratified manner over the inclined, air-flowed and vibrating shift table surface in such a way that the heavy admixtures lying directly on the shift table are upstream of the table promoted and removed separately at the higher table end.

In the past, attempts have been made in many different ways to divide a grain mixture into heavy and light grain fractions. A central problem is the selection of stones from the grain. Stones, broken glass, metal parts and other admixtures that differ significantly in size from the size of a medium grain are separated using sieves. As is known, the same types of grain as wheat, barley, rye, oats, spelled, but also other seed s, such as coffee, cocoa beans, field beans, seeds, flower seeds, etc. the outer dimensions of the grains in a relatively narrow range of grain sizes. What is larger than a certain perforation or smaller than a second finer perforation can be easily separated as a different good by simple sieving. The difficulty lies in reading out the foreign components, which are roughly the same size as the good grain, and carrying them away separately.

In the past, a water bath was often used; in which all foreign matter, heavier than the grain, sank to the bottom of the water bath. The gravity effect and the buoyancy of the water were used. The main advantage of this method was the simultaneous washing effect of the grain. Because of the wash water also produced as a result and partly because of the associated microbial problems, this solution has been replaced almost completely by the so-called dry cleaning for several years.

During dry cleaning, vibrations and a strong air flow over a table surface basically generate similar buoyancy forces to those used in the wash water. In practice, the generic method of reading for stones already proposed by the applicant has become the most popular in the past two decades, at least where high demands have been placed on the degree of reading (see DE-PS 1 913 707). First, a pre-layering is created along a pre-layer channel. The heavy additions sink to the area near the table. Then, at the same time, the light layer lying at a distance above the table slides over the table surface in the direction of the end which is at its lowest due to the inclination, or to the corresponding outlet for the lighter fraction. The heavy admixtures lying on the table surface are caused by the swinging and conveying movement of the table surface in the direction of the higher end of the table, the stones being completely separated in an end separation zone and discharged via the corresponding outlet. The main disadvantage of this well-known solution is the specially required triangular shape, which only allows a limited increase in the throughput.

As a result, various other solutions have been tried, but without resounding practical success. In the majority of cases it was not possible to achieve the readout quality of the first-mentioned solution. Various attempts have been made to operate with two work tables lying one above the other, the upper table mostly having a sieving and layering function, as shown for example in DE-OS 25 33 274. With this solution, it is only possible with additional measures such as special internals, etc. to achieve an essentially perfect, i.e. H. to reach almost 100% stone selection.

From GB-PS 1 536 905 a grain separator is known in which an air flow is generated with the aid of a fan arranged under an inclined and perforated chute. The housing, which houses the entire separator and fan, is rigidly arranged and only the receiving table can be moved.

The classic air recirculation system is disclosed here, but in practice there were always problems with the pressures in the respective sections of the housing. In particular, the problem of so-called false air could not be eliminated.

Finally, the air guidance was problematic in the known grain mixture separation methods, in particular heavy goods selection methods, which applies in particular to the mutually undisturbed, optimal material and air guidance, including the supply of good and air, with the consequence of a Limiting the improvement in throughput, especially with good selection.

The invention is based on the object of providing a new method for reading out heavy admixtures, in particular a new stone selection method and a device for carrying out this method or a new dry gravity reading system which allows a higher throughput.

This object is achieved in a generic method in that the material is fed as a wide-area stream in the region of the separation zone of the material layers located at the higher end of the table.

The first practical experiment with the new ^{idea of the} invention was surprising in two ways. Firstly, the readout rate was immediately unexpectedly high, and secondly, the inventor chose an infeed point which, according to all previous conviction, must have been wrong among experts. However, she did achieve the desired success. So far, not least based on the idea of pre-separation (see DE-PS 1 913 707), the method was presented in two spatially and temporally separate steps. The first step was stratification, the layer near the table should contain all heavy admixtures, and only as a subsequent step should the layering provided in a channel be fed undisturbed onto the table surface and the stones to the outlet for the stones. It was only in the area of the highest reading table end that the stones were effectively separated and routed separately. The heavy admixtures should usually only make up a very small percentage of the grain, so that the final separation zone had the smallest dimensions (the tip of a triangle), because only a small proportion of the entire product quantity was carried up to that point. Were now the final separation zone or the table inclination set incorrectly, where too much grain could get there or if the local air flow was chosen unfavorably, then either the stone selection was bad or the stones were several times more good grains. The final separation zone was then also a point that always had to be specially monitored. The thought of pouring a large amount of fresh grain in the stone separation zone onto the table would have been completely absurd. Any disturbance at this point showed an immediate deterioration in the way the reading tables work.

Because the inventor has completely detached himself from all previous conceptions and the supposedly derived unchangeable natural laws,

be it that a pre-separation is necessary at all, and this takes time and effort to separate the heavy admixtures or by placing the product over a larger area of the table, in the opinion that each stone then has the greatest possible chance for the secretion,

he was only able to free himself and realize the new idea unencumbered, which consists in particular in that

the material is fed in as wide as possible and the material is fed directly into the area of the separation zone at the top of the table.

The shift table should work as a good shift table in that it is designed in such a way that the heavy admixtures below are conveyed upwards. In this way, with a product task at the higher table end, the most heavy admixtures remain in the Area of the separation zone. Should they be dragged down a bit, they will migrate back up to the final separation zone with even greater certainty than all previously known solutions. Now it is only a question of the clean design of the final separation zone, the correct setting of the air volume and table inclination to achieve an optimal way of working. The invention enables particularly good conditions for easy practical optimization in that, by creating a wide stream of material, the final separation takes place at the maximum possible width, that is to say without an unnecessary layer thickness.

The new invention now allows a whole number of further, particularly advantageous configurations. For example, a uniform layer flow (difficult upstream, slightly downward) with reversal of flow direction in the region of the higher end of the shift table is preferably generated on the stratification table, and the product flow is fed directly into the region of the reversal of flow direction.

The reversal of the direction of flow for the light parts is generated in a manner known per se, a table piece which is continued further upwards also having air flowing through it, so that the light parts stand out from the table surface. At the same time, the product layer, with the exception of the stones, is prevented from moving further up the table by an air flow directed towards the separation zone and downstream of the table, which acts almost like a blower or air blast device (see FIG. 2).

In a further, particularly preferred embodiment, the material is first fed to a first, uppermost vibrating table and at least a first part of the heavy material fraction flowing upstream of the table and consisting of a mixture of heavier grain material and stones is guided at the upper end of the first table in such a way that the heavy goods fraction from there to the upper area

End region of a table surface through which the same air flows is fed to a second, lower layer table located underneath.

This measure allows approximately half the throughput from the upper table surface, which now contains almost 100% of all heavy admixtures, to be discharged onto the lower table as a heavy layer. The actual separation of the heaviest additions to be separated takes place here on the lower table. In this way, the throughput can be doubled in a single device with the same amount of air, and without the slightest loss of separation quality.

In a further preferred embodiment of the method according to the invention, the material is moved upwards on the upper layer table with a lower conveying component than on the lower layer table, and a second part of the heavy material fraction is fed from the upper layer table to the lower end region and / or the middle of the lower layer table.

This has the advantage that the stone selection takes place in two temporally and spatially separate stages.

The product stream is particularly preferably fed in via a guide plate arranged at a distance above the table surface. As a result, the product stream can advantageously be conducted across the entire table width of the shift table.

It is also proposed to feed the product stream in the direction of the flow direction of the light grain layer (or against the flow direction of the heavy grain layer).

In a particularly preferred embodiment of the In order to separate the heaviest admixtures (stones) from the shaped material, the method according to the invention is blown onto the separation zone in the direction of a reversal of the direction of flow of the heavy grain material migrating up the table.

This has the advantage that a promotion of the light parts or grains together with the heaviest additions on the table is prevented.

In a further particularly advantageous embodiment of the method, the blow-back flow is conducted between the guide plate and the layer table. In this way, it is in particular possible to guide the air flow in a simple manner, through which the heavy and light particles of the goods can be separated.

In a further preferred embodiment of the method, the at least one shift table, together with a covering assigned to it for recirculation mode, is set in common vibrations with separate guides for supply and exhaust air.

This has the advantage that the entire system has a self-cleaning effect. Adhering dust particles are shaken off continuously by the shaking movement. This eliminates the need for time-consuming cleaning. This ensures that the flow paths are not changed in their cross-sections by adhering particles, so that constant flow conditions can always be guaranteed.

Since the individual elements are arranged within the cladding and the cladding can vibrate with it, the good is continuously shaken when the good is fed onto the good table.

The fact that table as well as good distribution elements shaken at the same time, the veil-like, widespread spread of the material on the shift table, which is essential for the separation process, is obtained. This joint formation of the elements within the cladding essential for the separation process also has the advantage that the sealing problems disadvantageous in the prior art can be avoided.

In a further, particularly preferred embodiment, the cladding, together with the layer table, forms a box which is supported for swinging and the box, including the layer table, is set in common vibrations.

Another very advantageous design idea is that the material feed takes place as a wide-area stream in the area of the separation zone of the material layers located at the higher table end, the air is removed from the center of the top panel and is supplied in a wide area in the area of the lower table end. This has the advantage that the air supply acts on the entire table width from below right from the start. It is also possible to achieve an air flow within the box that works almost without undesired eddy formation.

Due to the compact, elegant design and the transmission of the required vibrations to all components, it is suddenly possible in a simple manner to separate the individual functions from one another and to fasten the paneling in a sealing manner.

In a further preferred embodiment of the method, the circulating air in the region above the central air discharge and the lower air supply is cleaned of dust components. This allows the flowing air to be cleaned advantageously at a time when undesired eddy formation occurs Laxative elements for cleaning are not yet able to interfere with the air flow acting on the table.

In a further preferred embodiment, the material on the upper layer table is guided over a trough-shaped recess (stone and material swamp), the heavy material fraction that enters the recess is passed over bottom openings of the recess and then over an opposite direction to the upper layer table - An inclined slide is directed to the middle floor of the lower layer table, whereas the light material fraction overflowing in the flow direction of the trough-shaped depression of the upper layer table is fed to an outlet for light material. In this way, the heavy layer can advantageously permanently sink completely into the stone sump and be discharged directly downwards. This results in a very high degree of selection for the heaviest admixtures and, in addition, a clean separation can be carried out with only minimal additional effort.

In a particularly preferred embodiment, a shifting suction hood and a stationary platform arranged above it are assigned to the shift table, the material being fed in via an inlet in the stationary platform, passed via flexible sleeves into a distribution box of a dining channel that moves with the suction hood, and cascading from the distribution box a guide plate is poured, so that multiple falling currents are generated across the entire width of the shift table.

The invention further relates to a device for separating and reading out heavy admixtures from a product stream, in particular stones from grain material, with a feed channel for feeding the product stream onto an air-flowed, vibratable, inclined shift table with an oscillating conveyor component in the direction of the higher table end. The object mentioned above in the context of the method is achieved in a generic device in that the feed channel opens into the region of the higher table end.

The first test results with the new device were particularly surprisingly good, since with the same readout rate and the same air consumption the material throughput could in some cases be increased by more than 50%, without the construction of the new device requiring major structural expenditure.

In a preferred embodiment of the device according to the invention, the feed channel opens out over the entire width of the shift table. This has the advantage that a wide and generous loading of the material to be separated is possible.

In a very particularly preferred embodiment, the mouth of the feed channel has a guide plate arranged at a distance above the shift table. This guide plate has the advantage of distributing the material to be loaded evenly over the shift table and at the same time serving on its underside as a guide for air currents.

In another preferred embodiment, the feed channel has a distribution box and a guide plate, which form a cascade for the feed product flow to generate a uniform falling flow over the entire width of the shift table.

In a particularly preferred embodiment, the guide plate has an overflow edge and bottom openings in the region of its end pointing in the direction of flow, in such a way that the majority of the material flows as a wide-area flow of material onto the shift table and the heavy ones Additives can be drained through the bottom openings. With this overflow edge, a particularly wide area of the product flow is achieved, because after the full width of the trough in front of this overflow edge has been filled, a uniform flow then flows, which is fed by the trough, down onto the layer table below.

In a preferred embodiment, an end separation zone for reading the stones is arranged between the guide plate and the table surface of the layer table.

A further breakthrough with regard to higher throughputs could only be achieved by arranging two jointly vibrating shift tables directly one above the other and through which the same air flows.

The lower layer table preferably has a larger conveying component in the upward direction than the upper layer table, the surface of which is rougher than that of the upper layer table. As a result, the upper layer table advantageously serves as a pre-layer table. It is also advantageous if the upper layer table has at least one discharge opening serving as a feed channel for the lower layer table at its higher end. In this way, a small fraction of heavy goods can be directed directly to the higher end of the lower table.

The feed channel for the lower shift table particularly preferably extends over the entire width of the upper shift table, in order in turn to produce a uniform distribution of material on the lower shift table.

The two shift tables are advantageously arranged to one another in such a way that the upper shift table feeds well onto the upper table end of the lower shift table. In this way it is possible that almost the entire proportion of the material to be separated is fed in at the location of the lower table where the unexpectedly good separation is possible.

The at least one shift table is particularly preferably part of a box which vibrates together with it and is designed for recirculation mode.

This has the advantage that not only the shift table, but also the associated table. Box is shaken. A self-cleaning effect can thus be achieved in that adhering dust particles can be shaken off while the system is operating.

At the same time, it is possible to design the entire system inside the box without the usual sealing problems, because the system according to the invention is tight on the outside, so that the air inside can be controlled in a targeted manner.

If the system inside the box were not sealed against the outside air, you would get secondary air that would disturb the entire air duct system. It is also advantageously possible to introduce air over the entire lower table surface in the lower region of the product table. Overall, therefore, is an optimal Produktzu¬ management with the possibility of wide-scale Auffäche- ^"rung with simultaneous optimum air supply without product supply and air supply may interfere mutually achievable.

In a further advantageous embodiment of the device, the material feed is part of the box. This has the advantage that the material feed resonates with the box and, as a result of this oscillating movement, the material is loosened before it hits the shaking table and forms a so-called veil. That veil is the guarantee for a wide distribution on the table. In addition, with simultaneous cleaning due to the shaking movement, the feeder can also be cleaned.

In a further preferred embodiment, the following are provided within the box: an air suction space and a circulating air supply duct separate therefrom, which opens in the region of the lower end of the at least one shift table. This makes it possible to design the air suction space and also the circulating air supply duct so generously in terms of size that no large constrictions trigger undesired eddies or other unpleasant flow effects. The entire air flow can be guided through the tables without interference within the box and, in particular in the width of the lower surface ^'of the bottom table, can pass through this evenly over its full width.

In a further preferred embodiment of the device according to the invention are arranged on the top of the box: on one end a good inlet, approximately in the middle an air suction nozzle and on the opposite end side an air return line for the recirculation duct. This makes it possible to extract the circulating air conveyed through the respective shift table in the middle under good flow conditions, without a disturbance of the flow properties being expected from the material fed in. With the lateral feed of goods, it is still possible to feed the goods to be fed into the middle of the shift table to be fed. At the same time, this preferred embodiment makes it possible to conveniently suck the air out over the middle. This leaves enough space for the air circulation duct, because the so-called outlets for the goods can be made relatively narrow without interfering with the routing of the goods. As a result, the air supply from the bottom can be wide from the start in the lower area of the shift table, that is, it can feed the entire width of the table from below. take place.

In a further particularly preferred embodiment, the box is mounted so as to be capable of swinging in a frame which has a stationary head piece in its upper region, the head piece being connected to the box via the air extraction nozzle with a circulating air separator and via flexible sleeves. Due to this compact and elegant design, sealing problems can • only. on the three nozzles on the box surface, which are connected to the stationary part of the non-oscillating frame, the head, via flexible sleeves. The seals can be designed to be particularly reliable since flexible sleeves that have been tried and tested for a long time can be used for this purpose. The operational safety through the seals ultimately leads to a trouble-free flow within the box.

In a preferred embodiment, the circulating air separator is connected to a suction fan and to a dust discharge line. In this way, the disruptive part of fine shells and dust can be removed from the air flow. It is also advantageous to connect the air recirculation duct to an aspiration connection for fine dust filters. A dust accumulation in the entire device can thereby advantageously be avoided and operational safety and hygiene increased. Due to the recirculation mode, only a small proportion of the total air volume has to be passed through the fine dust filter.

In a further preferred embodiment, the upper table surface in its lower region has a trough-shaped depression (stone or manor swamp) with through openings in the trough bottom for additional separation of the product stream into a heavy and a light fraction. - In addition, with the invention, a high degree of stone reading can be carried out, specifically reading out any foreign heavy parts still present in the sieved grain. In addition, little air is advantageously used and that

- The method and the device are simple and, in particular, not very sensitive to fluctuations in throughput.

Some exemplary embodiments of the invention are explained in more detail below. This shows 0

Fig. 1 ^' the simplest form of a small table reader for stones, Fig. 2, the product feed on the shift table, Fig. 3 the same approach as Fig. 1, but with 5 two table surfaces, especially for a large one

4, a solution according to FIG. 1, but with a

5, a solution according to FIG. 3, but with a 0 air duct,

zeigt die - Vorrichtung wie bei den Fig. 3, 7 und 8 mit durch den Kasten geführtem Umluftka- 0 nal.6 shows FIG. 5 with a circulating air separator, FIG. 7 is a solution similar to FIG. 3 with additional formation of two gravity fractions in addition to the stone selection, FIG. 5 is an embodiment variant of FIG. 7, shows a stone sump on the layer table surface,

shows the - device as in FIGS. 3, 7 and 8 with the air duct led through the box.

In the following, reference is now made to FIGS. 1 and 2. 1 shows a basic type for a new stone reader 1, the fresh grain being passed through 5 an inlet 2 to a shift table 3 and being discharged from there as cleaned grain via an outlet 4. A closed hood 5 is arranged above the shift table 3 and has a suction opening 6 having. The hood 5 forms, together with the shift table 3, an oscillation device 7, which can be set in motion by a vibration exciter 8 with an oscillation component in the direction of the upper end of the shift table 3. The upper end of the layer table 3 is formed by a guide plate 19 as an end separation zone. The entire vibrating unit 7 is supported by spring elements 9 on a frame 10 which is fixed on a floor 11. Also fixedly connected to the frame 10 is a non-vibrating head piece 12, in which the inlet 2 and an air suction line 13 are attached. In addition, an air quantity adjusting flap 14 is arranged in the air suction line 13 for setting the air aspirated by the whole stone reader 1. The connection of the vibrating parts, or the vibrating unit 7 and the head piece 12, takes place via flexible sleeves 15, which are arranged after the inlet 2.

When viewed in plan, the layer table 3 preferably has an at least approximately rectangular shape. On the side of the higher end of the shift table, the shift table 3 can be pulled out for service work. The product transfer point extends across the full table width. The width is designated in FIG. 2 with "B", the layer thickness with "D". The formation of a wide-area flow of goods 20, also known as good veils, for the purpose of feeding in goods takes place in two stages. As part of the swinging hood 5, the fresh grain is guided in a distribution box 17. The oscillation promotes the uniform, broad distribution of the grain material in the distribution box 17, which, in order to intensify this effect, is widened downwards and is cascaded. The same purpose is served by a stowage flap 18 also provided in the distribution box 17, so that the grain material is passed as a wide-area product stream directly onto the guide plate 19 extending over the entire table width and then as a uniform, wide product stream 20 onto the layer table 3. The wide spread device of the product stream 20 is further supported by the fact that the guide plate 19 has an overflow edge 16 at its free end, and is therefore of a trough-shaped design. For the pre-separation of heavy and light goods, the trough-shaped guide plate 19 can also have bottom openings for the passage of the heavier admixtures.

The wide, uniform product flow spread on the shift table 3 is particularly illustrated in FIG. 2. In the same figure, the stratification is deliberately overemphasized. The sheet table 3, a situation as Produktauf¬ rough mesh 21 and is constructed in a ^'per se known manner in the so-called sandwich construction, wherein the mesh 21 forms the top, supported by a honeycomb shape disposed Blechstrei¬ fen 34 which downwardly by a fine perforated plate 22 are held. In the individual fields 23 between the metal strips 34, cleaning bodies 24 are arranged which keep both the mesh 21 and the perforated plate 22 clean. It is also important here that the perforated plate 22 has an air resistance which is much greater than the air resistance of the mesh grille 21, e.g. B. in the order of 1: 10. With this measure, the air distribution can be kept approximately constant over the entire surface of the layer table 3 regardless of the layer thickness on the mesh screen 21.

The material stratification itself essentially consists of three different layers, a lower, heavy layer 25 containing the heavy admixtures being conveyed upward by the mechanical throwing motion. A light layer 26 freed from the heavy admixtures is kept in suspension not only in the relaxed state but also at a distance above the mesh 21 by the targeted air flow. Since the layer table 3 is slightly inclined and the upper light layer 26 does not directly face the table Received delivery pulse, but is kept in vibration, this swims towards the lower side of the table. In addition, the inclination of the shift table 3 can be adjusted by an adjusting device 35. A third stratification 27 consists of the actual heavy admixtures, mostly only individual particles, individual foreign bodies, stones 28, etc. Good, heavy grains 29 and light parts, e.g. B. half grains, shell parts 30 are shown in the approximately corresponding shape. The heavy goods with the stones 28 immediately sink onto the vibrating table surface 7 and move up the table due to the "vibration and the rough table surface formed as a mesh 21.

For the function described, it is now important that the air flow is guided correctly. The whole ^{'Schichttisch¬} surface is flowed through from bottom to top by a suction air flow whose flow direction is indicated by arrows 31st This air flow 31 brings the grain to a highly fluidized state. Since only the heaviest parts, ie the stones 28 are to be separated onto the higher end of the table and are to be conveyed from there into a stone lock 45, a corresponding blowback stream 33 is formed which prevents light parts or grains with the heaviest additions be promoted upwards. The blow-back stream is preferably formed under the guide plate 19. If the guide plate 19 is firmly connected to the hood wall, the air guided into the slot between the guide plate and the shift table can only escape in the direction 33.

With the exception of the stones 28 located therein, the material is prevented from moving further upwards by the air flow in front of the final separation zone. The stones 28 can continue their movement towards the higher end of the table. The same blow-back flow 33 causes a flow front or flow direction reversal 32 which is clearly established in practice. At the location of the flow direction reversal 32, the grain 29 freed from the stones 28 is lifted off the table surface by the strong air flow 31, 33 and now flows freely together with all light goods with the upper lifted light layer 26 down the table. The lightest fraction ^'is immediately gen ausgetra¬ at the outlet 4; a medium grain fraction can possibly make a circular traveling movement up-table-down several times, which is particularly true for boundary grains.

In FIGS. 1 and 2, the product stream 20 is fed directly into the zone of the flow direction reversal 32. The reversal of the flow direction 32 is generated from the three forces of mechanical conveying action upward, swimming down the upper layer 26 downward from the table, and blowback flow 33.

The main structural difference between FIG. 3 and FIG. 1 is that in FIG. 3 two shift tables, an upper shift table 3a and a lower shift table 3b are used. Basically, both shift tables 3a and 3b have the same structure, e.g. B. as in FIG. 2. In principle, the blow-back flow 33 is absent from the upper shift table 3a, so that not only the heaviest admixtures, but the entire heavy shift 25 are moved up the table and can fall onto the guide plate 19 through a discharge channel 40 via a steering plate 41. Starting from the guide plate 19, the mode of operation of the shift table 3b is identical to that of the shift table 3 of FIG. 1 and 2 respectively.

To prevent the freshly entering product stream 20 from the distribution box 17 from being mixed directly with the heavy layer 25, a guide plate 42 is arranged at the uppermost point between the distribution box 17 and the shift table 3a. The flowing product stream is discharged via a product lock 43 directly into an outlet channel 44 of the lower layer table 3b. The two streams of material from the two shift tables 3a and 3b freed from the heaviest admixtures are then brought together again in the outlet 4. All the heaviest admixtures, such as stones 28, etc., are first separated from the upper layer table 3a together with the heavy layer 25. The actual separation and the separate removal of the stones 28 via the stone lock 45 then take place on the lower layer table 3b. The stone selection takes place here in two temporally and spatially separated stages. This is because concentrate is first formed with all heavy goods, e.g. B. 30% to 60% of the entire material throughput on the upper layer table 3a and only from the reduced material throughput the stones and other heaviest admixtures are read out and carried away separately.

FIG. 4 is identical to FIG. 1 in terms of product management, and FIG. 5 corresponds to FIG. 3. The solution concept of FIGS. 4 and 5 additionally contains a box 50 which is closed all round, which can be closed by the, respectively the shift table (s) is divided into an upper suction chamber 51 and a lower suction chamber 52. At the lower end of the or the layer table (s) there is a recirculation channel 53, which is connected to an air return line 55 via a flexible hose 54 and an air return pipe 55 '. An air flow restrictor 56 is arranged in the air return line 55. 4 and 5, the box 50 itself is supported on the fixed frame 10 by means of spring elements 9. On the top of the box 50 there is an inlet spigot 2 'connected to the material inlet 2 at one end, approximately in the middle an air outlet 13' connected to the air suction line 13 and an air return socket connected to the air return line 55 on the opposite end side 55 'arranged. The previously mentioned nozzles 2 ', 13',

55's are connected via flexible sleeves 15, 54 on the one hand to the non-oscillating head piece 12 and on the other hand to the box 50 in order to be able to participate in its movement in this way. In the double machine in FIG. 5, two outlets 4 are arranged as tubular product channels 57 on both sides (perpendicular to the image plane), so that the remaining space between the two product channels 57 remains for the circulating air channel 53. The box. 50 is framed in Figures 4 and 5 for better identification with a dashed line.

In addition to FIGS. 4 and 5, FIG. 6 additionally shows a circulating air separator 60 with a suction fan 61 and a motor drive 62. The air extraction nozzle 13 leads directly into the circulating air separator 60, the essential or disruptive part of fine shells and dust being removed from the air flow via a dust discharge line 64.

In most cases in which recirculated air is used, air cleaning is advantageous because it can effectively avoid dust accumulation in the entire device and increase operational safety and hygiene. The recirculation mode has the great advantage that only a minimal amount of air, e.g. B. 10% of the circulating air volume must be passed through fine dust filters. For this purpose, an aspiration connection 65 is provided. The circulating air separator 60 can be attached directly to the ceiling 66 with a fan.

FIG. 7 has a fundamental difference compared to FIG. 3 in that only a small part of the material throughput from the upper shift table 3c at the highest point through a row of larger holes 71 over the entire table width in FIG. 7 , is given down to the overhead zone of the flow direction reversal of the lower layer table 3d. The Most of the heavy goods are passed in the area of the lower table end via a chute 72 approximately to the middle of the lower layer table 3d, again over the entire table width. Many series of measurements have shown that, with this solution, the large part of the stones is nevertheless released through the holes 71 directly onto the lower layer table 3d. In the solutions according to FIGS. 7 and 8, it is important that the upper layer table has only a less rough surface than the lower layer table 3d, as shown in FIG. 9, by the upper layer table 3c made of perforated sheet metal and the like lower layer table 3d is formed from mesh.

A particularly interesting, independent idea is now shown in FIGS. 8 and 9. This is the use of a stone sump 80 in the area of the upper layer table 3c. The method of operation is as follows: The stone sump 80 consists of a trough-like depression 81 which extends over the entire width of the layer table 3c. Similar to FIG. 2, two different layers are formed in FIGS. 8 and 9, namely the heavy layer 25 and the light layer 26 freed from the heavy additives.

Because the surface of the upper layer table 13 has only a slight roughness, there is no actual upward flow; at least the whole heavy layer 25 cannot be moved up. Rather, the lower heavy layer 25 flows down the table with a considerable delay, as is indicated by the single arrow 82. In contrast, the light layer 26 flows down the table at high speed (double arrow 83). The heavy layer now sinks, once it has reached the area of the recess 81, into the stone sump 80. The stone sump 80 now has a number of through openings 84 on its bottom, through which part of the material, together with the stones, continuously reaches the bottom lying slide 72 or the lower shift table 3d is carried out. With the correct coordination of the number of effective diaphragm openings 84 in relation to the mass flow of the heavy layer, the light and heavy layers can be separated such that the heavy layer 25 continuously sinks completely into the stone sump 80 and is discharged directly downwards. This has two major advantages:

1. This results in a very high degree of selection for the heaviest admixtures (stones, etc.)

2. In addition to separating the heaviest admixtures into a clean heavy fraction (good

Grains) and the rest into a light-good fraction (shells, grainy and broken grains).

It is thus possible to carry out the separation into the different basic fractions (stones, etc., heavy, light) in a single device and with very high quality.

Finally, FIG. 10 shows a device which functions according to the same principles as the devices according to FIGS. 3, 7 and 8. For this reason, there is no need to repeat the description of the same components at this point. The device according to FIG. 10 differs from the aforementioned devices only in that a recirculating air duct 53 "is arranged separately in the box 50 and the influence it has on the flow properties of the air in the box 50 can be avoided.

Claims

Claims 1. Method for reading out heavy admixtures, in particular stones (28) from grain material, in which the material is fed onto a shift table (3; 3b; 3d) and is guided in a layered manner over the inclined, air-flowing and vibrating shift table surface, that the heavy admixtures lying directly on the layered table (3; 3b; 3d) are conveyed upstream of the table and discharged separately at the higher end of the table, characterized in that the material flows as broadly as possible into the area of the higher end of the table Separation zone of the good layers (25, 26) is fed. 2. The method according to claim 1, characterized in that on the layer table (3; 3b; 3d) a uniform layer flow (25, 26) (heavy (25) table-open upwards, slightly (26) down the table) with flow direction reversal (32) in the region of the higher end of the stratification table (3; 3b; 3d) and that the product stream (20) is fed directly into the region of the flow direction reversal (32) - will. 3. The method according to at least one of the preceding claims, characterized in that the ut is first fed to a first, upper layer table (3a; 3c) and that at least a first part of the upstream table, from a mixture of heavier grain (29) and stones (28) consisting of heavy goods fraction (25) is guided at the upper end of the first table (3a; 3c) in such a way that the heavy goods fraction (25) spreads widely from there to the upper end region of a table surface through which the same air flows and a second surface below , lower layer table (3b; 3d) is fed. - 4. The method according to claim 3, characterized in that the material on the upper shift table (3a; 3c) is moved upwards with a lower conveying component than on the lower shift table (3b; 3d) and a second part of the heavy goods fraction (25) from the upper Shift table (3a; 3c) is fed to the area of the lower end and / or the center of the lower shift table (3b; 3d). 5. The method according to at least one of the preceding claims, characterized in that the Produkt¬ stream (20) via a spaced above the table surface guide plate (19) is fed. 6. The method according to at least one of the preceding claims, characterized in that the product flow in the direction of the flow direction of the light grain layer (26) (or against the flow direction of the heavy grain layer (25)) is fed. 7. The method according to at least one of the preceding claims, characterized in that for separating the heaviest admixtures (stones (28)) from Grain (29), an air stream (blow-back stream 33) is blown onto the separation zone (32) in the direction of a reversal of the direction of flow of the heavy grain (29) traveling up the table. 8. The method according to claim 7, characterized in that 'the blow-back stream (33) between the guide plate (19) and the layer table (3; 3b; 3d) is performed. 9. The method according to at least one of the preceding claims, characterized in that the at least one shift table (3; 3a; 3b; 3c; 3d) together with an associated panel for recirculation mode with separate guides for supply and exhaust air in common vibrations becomes. 10. The method according to claim 9, characterized in that the cladding together with the shift table (3; 3a; 3b; 3c; 3d) forms a vibratably supported box (50) and the box (50), including the shift table (3rd ; 3a; 3b; 3c; 3d) is set in common vibrations. 11. The method according to claim 9 or 10, characterized gekenn¬ characterized in that the good feed as the widest possible flow in the region of the separation zone (32) located at the higher end of the table Gutschichten (25, 26) takes place, the air is removed from the center of the cladding at the top and supplied over a wide area in the area of the lower end of the shift table becomes. 12. The method according to at least one of claims 9 to 11, characterized in that the circulating air in the area above the central air discharge (13) and the lower air supply (23) is cleaned of dust components. 13. The method according to at least one of the preceding claims with two arranged directly one above the other Shift tables (3c, 3d) characterized in that the goods are guided on the upper shift table (3c) over a trough-shaped depression (stone and manure sump (80)), the heavy goods fraction (25) entering the depression via floor openings (84 ) the Deepening and then via a slide (72) inclined in the opposite direction to the upper layer table (3c) onto the central region of the lower layer table (3d), which in the direction of flow of the trough-shaped recess (80) of the upper layer table (3c) overflowing light material fraction (26), however, is fed to an outlet (44) for light material. 14. The method according to at least one of the preceding claims, characterized in that the shifting table is associated with an oscillating suction hood and a stationary platform (12) arranged above, the material being fed via an inlet (2) into the stationary platform (12) , passed through flexible sleeves (15) into a distribution box (17) of a feed channel that resonates with the suction hood and is poured from the distribution box (17) in a cascade-like manner over a guide plate (19), as a result of which drop current is generated in a multitude of ways across the entire width of the shift table becomes. 15. Device for separating and reading out heavy admixtures from a product stream (20), in particular stones (28) made of grain material (29) with a feed channel for feeding the product stream (20) onto an inclined layer table through which air can flow and can be set into vibrations ( 3; 3b; 3c) with an oscillating conveyor component in the direction of the higher table end,. characterized in that the feed channel in the area of the higher The table ends. 16. The apparatus according to claim 15, characterized gekennzeich¬ net that the feed channel over the entire width of the shift table (3; 3b; 3c;) opens. 17. The apparatus of claim 15 or 16, characterized in that the mouth of the feed channel has a guide plate (19) arranged at a distance above the layer table (3; 3b; 3d). 18. The device according to at least one of claims 15 to 17, characterized in that the feed channel has a distribution box (17) and the guide plate (19) which form a cascade for the food product stream to generate a uniform falling stream over the entire width of the shift table. 19. The apparatus of claim 17 or 18, characterized in that the guide plate (19) in the region of its end pointing in the direction of flow has an overflow edge (16) and bottom openings, such that the majority of the goods as a wide-area flow of goods (20) the shift table (3; 3b; 3c) flows and the heavy admixtures (28, 29) are discharged through the bottom openings. 20. The device according to at least one of claims 17 to 19, characterized in that an end separation zone for the reading of the stones is arranged between the guide plate (19) and the table surface of the stratified table (3b). 21. The device according to at least one of claims 15 to 20, characterized in that two jointly vibrating shift tables (3a; 3b; 3c; 3d) - arranged directly one above the other and through which the same air flows. 22. The apparatus according to claim 21, characterized gekennzeich¬ net that the lower layer table (3b; 3d) has a larger conveying component in the upward direction than the upper layer table (3a; 3c) and for this purpose its surface rougher than that of the upper layer table (3a; 3c ) is. 23. The apparatus according to claim 22, characterized in that the upper layer table (3a; 3c) has at its higher end at least one discharge opening (40; 71) serving as a dining channel for the lower layer table (3b; 3d). 24. The device according to claim 23, characterized gekennzeich¬ net that the feed channel for the lower layer table (3b; 3d) extends over the entire width of the upper layer table (3a; 3c). 25. The device according to at least one of claims 21 to 24, characterized in that the two layer tables (3a; 3b; 3c; 3d) are arranged in relation to one another such that the upper layer table (3a; 3c) good on the upper end of the table Feeds shift table (3b; 3d). 26. The device according to at least one of claims 15 to 25, characterized in that the at least one layer table (3; 3a; 3b; 3c; 3d) It is part of a box (50) which vibrates together with it and is designed for recirculation mode. 27. The apparatus according to claim 26, characterized gekennzeich¬ net that a material supply. (2) is part of the box (50). 28. The apparatus of claim 26 or 27, characterized in that within the box (50) are provided: an air suction space (51) and a separate air supply duct (53), which is in the region of the lower end of the at least one shift table (3, 3b; 3d) opens. 29. The device according to at least one of claims 26 to 28, characterized in that on the top of the box (50) are arranged: on one end a good inlet (2), approximately in the middle an Luftab¬ suction nozzle (13) and on the opposite end side, an air return line (55) for the recirculation duct (53). 30. The device according to claim 29, characterized gekennzeichn¬ et that the box (50) is oscillatably mounted in a frame (10) which has a stationary head piece (12) in its upper region, the head piece (12) via the air suction nozzle (13) with a circulating air separator (16) and via flexible sleeves (54) with the box (50). 31. The device according to claim 30, characterized gekennzeich¬ net that the circulating air separator (60) with a suction fan (61) and with a dust discharge line (64) is connected. 32. Device according to at least one of claims 26 to 31, characterized in that the air duct (53) with an Aspirationsansσhluß (65) for fine dust filter is connected. 33. Device according to at least one of claims 15 to 32, characterized in that the upper table surface (3a) in its lower region a trough-shaped depression (stone or manor swamp 80) with through openings (84) in the trough bottom for additional separation of the product stream into a heavy (25) and a light fraction (26).