Device and method for fractionating and / or cleaning a material flow

Abstract

The invention relates to a device and a method for classifying and / or cleaning a material in a housing or a vertical arrangement, wherein: a starting material (AM) is fed to a housing (10) via an upper inlet (11) and passes, in the falling direction (G), successively through a plurality of regions (B1, B2, B3) for fractionation and / or cleaning; in a first region (B1), undesired matter is removed as a first fraction (F0) from the starting material (AM) and the remaining starting material (AM) passes through at least two screens (3, 5) of the regions (B2, B3), said regions being arranged in the falling direction (G); each screen (3, 5) removes at least one fraction (F1, F2, F3, F4) from the starting material; the material on the screens (3, 5) is transported in the same transport direction (6); and the pass-through fraction between the first and the second screens (3, 5) or between the second and the third regions (B2, B3) moves at least partially counter to the transport direction (6). In addition to a general device and a general method, in particular a preferred embodiment is to make possible an optimal fractionation or pre-cleaning of pre-comminuted waste wood in the course of the utilization of waste wood (1644).

Description

[0001] DEVICE AND METHOD FOR FRACTIONATION

[0002] AND / OR CLEANING A MATERIAL STREAM

[0003] The invention relates to a device for fractionating and / or purifying a material stream according to claim 1. The invention relates to corresponding methods according to claims 15 or 16.

[0004] The invention further relates to a device and a method for fractionating material streams, in particular pre-crushed mixed materials which may contain impurities.

[0005] Such devices are used industrially to classify solids into different fractions according to defined criteria, such as density, inertia, and size. Typically, in addition to similar materials, mixtures are also classified, for example, in recycling, to obtain pure fractions. The implementation of classification processes and the corresponding devices are demanding and maintenance-intensive systems in 24 / 7 operation or in large-scale industrial applications.

[0006] Such systems are available in a wide variety of designs and are generally familiar in the recycling industry. For example, plastics and metals are separated from returned broken bottles in the recycling cycle, the fragments are sorted by glass type and color, if necessary, and then remelted.

[0007] In the production of material boards based on lignocellulose-containing materials, foreign substances such as silicates, sand, dust are often found, but especially in waste wood recycling, metals, plastics and other foreign substances must be separated out before the cleaned material can be reused in large-scale industrial plants for the production of material boards, plastic boards or mixed boards. This typically involves a riser sifter for material to be recycled, in which an air stream is passed through a substantially vertical shaft against the force of gravity. Heavier material is not carried upward by the air stream and falls downwards, whereas lighter material is discharged in the upper area of ​​the shaft. The material to be sifted is usually fed in from the side of the air stream.In addition to the basic physical principle, a zigzag air classifier is typically used in the technological field of air classification for lignocellulosic materials, resulting in improved separation efficiency. This air classifier features zigzag channels that guide the air flow, allowing for repeated redirection of the air flow and the materials to be classified.

[0008] In a special purification process, WO 2023 046 989 A2 and WO 2023 046 990 A2 describe ways in which material streams can be divided and optimized for recycling. Two material streams consisting of solid wood and already compressed wood are created from a shredded material stream of waste wood.

[0009] The object of the present invention is to provide a device and a method which enable optimal classification and / or cleaning of mixed materials in the smallest possible space, in particular with regard to the possibility of recycling waste wood.

[0010] In an extension of the task, it should be possible to implement a contaminant removal system that can significantly reduce the volume or quantity of material to be cleaned in air classifiers, thus also reducing the necessary air circulation, which entails expensive construction and operation costs. The utilization of material streams should also be advantageously facilitated by classifying or fractionating a starting material in such a way that further utilization can be optimally tailored to the fractionated material streams, particularly with regard to downstream comminution devices to achieve specified grain sizes.

[0011] The solution to the problem for the device consists in the combination of features according to claim 1.

[0012] The solution is achieved by constructing a device for fractionating and / or cleaning a material stream in a housing or a vertical arrangement,

[0013] - wherein, after an upper inlet for the starting material, several areas for separating different fractions from the starting material are arranged successively in the direction of fall;

[0014] - wherein in a first region in or after the inlet a contaminant separator is arranged for separating a first fraction, preferably ferrous metal;

[0015] - wherein a first sieve for separating a second fraction of oversize particles is arranged in the second region;

[0016] - wherein a second sieve is arranged below the first sieve in a third region for separating at least a third fraction from the sieve passage of the first sieve;

[0017] - whereby the two superimposed sieves have a similar transport direction for the material on the sieves and

[0018] - wherein a transfer device is arranged between the two sieves and / or the second and third areas for at least partially transporting the sieve passage from the first sieve against the transport direction of the first sieve or sieves. The device and the corresponding method advantageously make it possible to clean a mixed fraction that has been pre-crushed before it enters a secondary shredder during recycling. Secondary shredding has the disadvantage that materials with an existing target grain size are further shredded. This ties up shredding capacity and reduces the quality of the mixed fraction for further recycling. In addition, the mixed fraction usually contains fine and very fine particles, as well as impurities from other materials, which further increase wear during secondary shredding.

[0019] The present method and device are therefore preferably used when a mixed fraction has been pre-crushed and needs to be crushed again to a suitable grain size for further use in industrial processes.

[0020] In a variant optimized for the solution, preferably for waste wood, the preparation of the starting material for the device and the process is carried out as follows:

[0021] - iron metal is separated using a magnetic drum,

[0022] - oversizes are separated using a disc screen,

[0023] - using a roller screen, three fractions are produced from the sieve passage of the disc screen, whereby

[0024] - the fine material is sent for its own recycling or discharged, as it usually contains tiny foreign matter or mineral dust,

[0025] - the material with the desired target grain size is fed into the planned recycling cycle and

[0026] - the enriched material with a grain size between fines and the target grain size is subjected to further cleaning or screening, for example a stone separator, because it is enriched with foreign or interfering substances.

[0027] Advantageously, the enriched material can be more easily purified and freed from foreign or impurities. The finally purified fraction is then usually added to the material of the desired target grain size.

[0028] In some recycling cycles, it may be necessary to re-grind or mechanically and thermally digest the target particle size. It is advantageous to remove any fines, dust, mineral components, or similar contaminants from the mixed fraction prior to this grinding or digestion, which significantly increases the service life of downstream machines.

[0029] The term target grain size refers to the result of the process and the device and a material that is suitable for further use, for example in the production of material panels or other utilization, and particularly preferably is sufficiently (pre-)cleaned.

[0030] During the separation process in the third section, e.g., the roller screen, four or more fractions can be formed. For example, a further fraction may already correspond to a specified grain size, which no longer requires grinding and / or is directly usable. This can be fed via a bypass for direct recycling, i.e., a material stream of the crushed target grain size from the first screen.

[0031] In addition to the recycling application, the solution also succeeds in requiring minimal space by forming a functional unit (magnetic drum, disc screen, Z-roller screen, and preferably a stone separator), which significantly reduces the investment costs for the building / land. Furthermore, by utilizing gravity (material falls directly from the first screen to the second screen), conveyor technology is generally not required between the screens, which can significantly reduce the investment costs for machinery.

[0032] Ultimately, it is now possible to adapt the previously required shredding capacity. Wear and tear is significantly reduced, and only material that needs to be shredded for recycling is shredded. Regular maintenance requirements and thus downtime are also significantly reduced.

[0033] The invention understands and defines the terms used essentially but not exclusively or conclusively as follows:

[0034] A material stream typically consists of loose or free-flowing material and exhibits the characteristics of a mixed fraction. The mixed fractions can essentially be divided into fractions, oversize particles separated, dedusted, and / or sorted. Oversize particles (screen residue according to DIN 66160) are generally particles that do not pass through the screen mesh size and can be separated as a separate fraction. In addition to gravity, optional additional force introductions and the specified mesh size are crucial for the screening effect. In addition to static screening surfaces, roller or roll screens can also be used. These are characterized by a large number of parallel arranged rollers / rollers. The mesh size results from the constant or variable openings between the rollers or their structures, such as discs, elevations, knobs, or the like.Known roller-shaped classifying devices also use flattened pyramids on their surfaces. To loosen the material to be screened, usually during accumulation conveying, spiky or angular elements can be mounted on the circumference of the rollers, for example, polygonal plates or star-shaped elements instead of round discs. The mesh size results from the interaction with the structures or elevations of the adjacent rollers. Especially during accumulation conveying, a classifying stratification of the demixed material flow can occur on the roller bed, for example, heavy at the bottom, light at the top, which can specifically discharge an enriched fraction adjacent to the rollers (contaminants with similar good material) through a predetermined larger gap. Such an enriched fraction can advantageously be cleaned in a targeted manner using adapted methods and thus with better selectivity in order to separate the good material.

[0035] The direction of fall essentially corresponds to the force of gravity, but can also contain vectorial horizontal components, for example in the case of a throw or an inclined sieve arrangement or through baffles.

[0036] Inlets and outlets are not necessarily limited to the housing; even within the housing, compartments such as screens can be separated from each other. Thus, this term essentially describes the separate supply and discharge of one material from another.

[0037] The device or method can contain or use control and / or regulation devices that properly control or regulate the device or method. Preferably, the device or method can be operated by means of AI (artificial intelligence) or as part of a machine-learned behavior. Possible input variables, but not limited to, are the quantity or properties of the starting material, as well as the quantity or properties of the various fractions. In particular, it can be possible to operate the individual sieves and / or the guide flaps to adjust the fractions using suitable sensors (weight, photographic grain size distribution, throughput per time, etc.). Advantageously, such a machine learning system is only made possible by corresponding algorithms and will only be able to deliver corresponding results after a training phase.It is common practice to create parameters or other comparative values ​​that can be used for control or regulation.

[0038] Machine learning is particularly preferred for the enriched fraction of the second sieve.

[0039] In an advantageous manner, this control or regulation can also have an effect on the upstream or downstream areas, for example on the subsequent cleaning, screening, transport or shredding devices, right up to the control or regulation of the subsequent recycling.

[0040] Furthermore, it should be noted that the implementation of the method does not necessarily have to be carried out using the device described and, in particular, does not necessarily have to be carried out using a transfer device between the two screens.

[0041] The following features may, individually or in combination, form further advantageous measures in connection with the device or method:

[0042] It is possible to assign a screening device to at least one fraction outlet for separating a further fraction and / or for cleaning the fraction. These screening or cleaning devices can preferably be magnetic drums, magnetic cascades for ferrous metals, eddy current separators for non-ferrous metals, heavy material separators (stones, glass, metals) or light material separators (foils, lint, fibers, textiles). These cleaning devices can also be used in the first area of ​​the process or device. Alternatively or cumulatively, a vibrating screen, a disc screen, a roller or roll screen, an air classifier and / or a throw classifier can be arranged as the first screen and / or second screen. In addition to these screens, screens that can distinguish measurable physical properties of the starting material or the previous screening pass are also suitable.

[0043] Preferably, a magnetic drum for metal separation, a non-ferrous metal separator, an eddy current separator, an air classifier, a sensor-based separation device and / or a heavy material separator can be arranged as a contaminant separator for separating the first fraction.

[0044] The transfer device can be a conveyor belt, a linear conveyor, a pneumatic conveyor, or guide plates inclined to the direction of the screen passage. Advantageously, the installation of a transfer device can significantly minimize the required installation space, because the required screens are not spread out over a large area but are arranged in tiers. The optionally unidirectional transport direction of the screens is particularly advantageous, allowing for a favorable design of the outlet openings and simple further processing or forwarding of the individual fractions.

[0045] Advantageously, the first screen and the second screen can be arranged essentially directly below one another. Depending on the design, a horizontal overlap of more than 50%, most preferably more than 75%, is also conceivable. This overlap enables an optimal arrangement of the outlets or may be technically advantageous due to the design-related configuration of different screens.

[0046] Preferably, at least the second screen is designed to discharge different fractions along the transport direction, which are preferably assigned to different outlets. Furthermore, the outlets do not have to discharge across the entire width, but can also bundle the fractions and discharge them laterally to optimize the installation space.

[0047] In one embodiment, at least one movable control flap, preferably perpendicular to the transport direction, can be arranged below the sieves. This control flap is suitable for adjusting the ratios of the different fractions to each other or for adjusting the properties of the fractions. The control flaps can also be arranged in a vibrating manner, if necessary, to prevent material from accumulating in inclined positions.

[0048] In a further preferred embodiment, a disc screen, a roller screen, or a star screen is arranged as the first screen in the second area, and a roller screen is arranged as the second screen in the third area. In this configuration, the first screen is particularly well suited for sorting large volumes of oversized material in the material flow and, if necessary or intended, simultaneously performing a classifying pre-screening along the transport direction. The oversized material is generally fed again to the pre-shredding stage or a crusher so that it can be converted to the specified grain size for later processing.

[0049] A disc screen preferably consists of parallel rollers on which discs are arranged at axially spaced intervals. The discs can be round or shaped, but square, serrated, or star-shaped discs are also conceivable. These are generally suitable for loosening the incoming material or transporting it in the direction of transport. Preferably, the discs of adjacent rollers mesh with each other.

[0050] Disc screens can be called star screens, disc screens with hexagonal discs, flip-flow screens, or finger screens, among others. A roller screen can also consist of rollers arranged parallel to one another, with raised surfaces. These raised surfaces preferably mesh with the adjacent rollers or are spaced at a predetermined distance. Particularly preferably, the raised surfaces consist of flattened pyramids.

[0051] Preferably, the disc screen and / or the roller screen can form a sifting effect from fine to coarse along the transport direction. This can be achieved in a simple manner, for example, by adjusting the spacing of the discs in a disc screen or by adjusting the spacing of the rollers in a roller screen.

[0052] In a specific embodiment, rollers with essentially equal spacing and / or elevations can be arranged in one or more regions of the roller screen for screening a fraction. Preferably, a larger spacing is provided between two of these regions to discharge a layer of the material resting on the rollers. This layer can be a layer enriched in foreign matter or impurities. Typically, this layer forms adjacent to the rollers and comprises similarly large and / or heavy particles enriched with further impurities. The spacing between the regions is operatively connected to a dedicated outlet for discharging a dedicated fraction.

[0053] Preferably, at least one outlet for discharging a fraction is operatively connected to a classifier or a heavy-material separator for producing a further-cleaned fraction. This can be implemented directly in the housing or, preferably, in the adjacent close vicinity. Advantageously, it may be possible to combine the further-cleaned fraction with a fraction that is adjacent in terms of grain size. Alternatively or cumulatively, at least one outlet for discharging a fraction, preferably with an outlet for oversize grain of a screen, can be operatively connected to a comminution device for further utilization. This comminution device is generally used in process engineering to reduce the classified and, if applicable, cleaned material to a predetermined grain size for later utilization.This is done, for example, to reduce wood chip sizes when recycling waste wood to chip or fiber sizes for use in the production of material boards (MDF, OSB, chipboard, ...) or in plastics production when recycling recycled plastic.

[0054] The solution to the problem for a method consists in the combination of features according to claim 15.

[0055] In this method, for classifying and / or cleaning a material in a housing or a vertical arrangement, a starting material is fed into the housing via an upper inlet. The material is successively passed through several regions for fractionation and / or cleaning in the direction of fall, wherein impurities are separated from the starting material as a first fraction in a first region and wherein the remaining starting material is fractionated by at least two sieves in the further regions arranged in the direction of fall, wherein each sieve separates at least one fraction from the starting material, wherein the material is transported on the sieves in the same transport direction and wherein the sieve passage between the first and second sieves or the second and third region moves at least partially counter to the transport direction.

[0056] The solution to the extended problem consists in the combination of features of the method according to claim 16.

[0057] In this process, the starting material, pre-shredded waste wood or a comparable mixture with wood components, is cleaned of ferrous metals in the first area, screened in the second area with a disc screen, preferably classifying along the transport direction, and the oversize grain is discharged as a fraction via a separate outlet, wherein in a third area below the second area in the same transport direction, the screen passage of the first screen reaches a roller screen of the third area in the direction of fall and is separated there into at least three fractions and fed to at least three separate outlets, wherein in the transport direction, the first fraction of the third area has a finer screen passage than the other fractions of the third area,the second fraction of the third area contains wood chips enriched with impurities and / or foreign substances and the third fraction of the third area contains wood chips that can already be further recycled.

[0058] Preferably, in one of the above processes, at least the second fraction containing the impurities and foreign matter can be passed through a screening device and / or a cyclone to remove the impurities and / or foreign matter. It can then be provided that this cleaned fraction is fed to the material flow of the third fraction for further utilization, preferably further comminution. Advantageously, an optimal fraction with a maximum chip size for further utilization or comminution was created here. The smaller wood chips were separated into a separate fraction with similarly sized impurities and were advantageously freed from dust or other smaller mineral foreign bodies. The cleaning of the second fraction of the third area is reliable and easy to carry out and can, for example, be easily removed if a heavy-duty and / or light-duty screen is used, in which stones, sand orLint, fibers, or films can be removed. This second fraction can then either be utilized directly, depending on its grain size, or fed to comminution together with the oversize grain from the second screen or the corresponding adjacent third fraction. Such comminution can also be thermal-mechanical digestion, for example in a digester and / or a refiner. The method preferably provides for the oversize grain from the first screen to be fed to (post-)comminution, wherein preferably the comminuted oversize grain is fed to the method and / or the device again, or the comminuted oversize grain is fed to the third fraction of the third region.

[0059] Particularly preferred starting material is shredded or broken recycled wood with a grain size of up to 300 mm for a first edge length, up to 400 mm for a second edge length, and up to 500 mm for a third edge length. Such starting material is usually available when waste wood is pre-broken in a drum chipper or a similar device. For example, these pre-broken sizes can be 400 x 500 x 50 mm.

[0060] Proposed process features usually require technical equipment for implementation and are accordingly also suitable for the device; vice versa, this also applies to the process-technical implementation of device features.

[0061] Further advantageous measures and embodiments of the subject matter of the invention emerge from the subordinate claims and the following description with the schematic drawing.

[0062] The drawing shows a schematic side view of the device 1 with a housing 10 having areas B1, B2 and B3 arranged therein in the direction of fall G. In a first area B1, the starting material AM passing through the inlet is guided past a contaminant separator 2. This ensures that, for example, ferrous metal EM reaches an outlet 12 as a separate fraction, while the remaining material in the housing falls into the second area B2. In the second area B2, a first screen 3 is arranged, which transports the remaining material in the transport direction 6 and screens it in the process. With optional classifying screening, preferably first finer and then stronger material is discharged as a screen passage in the direction of the third area B3. The oversize grain from screen 3 reaches its own outlet 16 as fraction F4.The oversize material can either be subjected to coarse crushing and optional cleaning and then returns to the device 1 via inlet 11.

[0063] Before the screening passage of the first screen 3 reaches the second screen 5 in the third area B3, the screening passage is shifted against the transport direction 6 of the screens. This ensures a compact design and simultaneously optimizes the screening process on the second screen 5. For shifting against the transport direction 6 of the screens, a transfer device 4 can be provided, which actively or passively moves the material against the transport direction 6. For example, guide plates, which may be assisted by vibration, are considered passive. Conveying devices not shown, such as conveyor belts or linear transfer devices or throwing rollers that accelerate the material, are considered active.However, it is particularly preferred if the sieve passage is shifted in sections as shown in the figure, in particular in the case of a classified sieve passage along the transport direction 6, in order to avoid an accumulation of the sieve passage at the beginning of the second sieve 5.

[0064] In the exemplary embodiment according to the drawing, the screening passage is preferably divided into three fractions by the second screen 5 in the third area. At the beginning of the screen 5, in the transport direction 6, a first fine fraction F1 is separated. This is followed by a second fraction F2, preferably enriched with impurities. A third fraction F3 can be formed, as shown in the drawing, as oversize particles from the second screen 5 or (not shown) as a third screening passage. The number of fractions is not limited; in particular, screen types other than perforated screens are capable of forming a multitude of different fractions, for example, actively driven roller or cylinder screens.

[0065] Fractions F1, F2, and F3 are fed to or guided through separate outlets 13, 14, and 15, respectively. The outlets do not necessarily have to discharge the fraction from the housing 10, but should be understood as conveying or guiding these fractions to the screen 5 as independent material streams that cannot be mixed with other fractions.

[0066] Below the second screen 5 or between the individual outlets 13, 14, 15, control valves 9 can be arranged, which can adjust the screen passage in the boundary areas between the individual fractions F1, F2, F3. These can be adjusted manually or via adjusting means and corresponding control or regulating devices (not shown). The drives, adjusting means, control or regulating devices not shown will be independently recognizable and implemented by a person skilled in the art, provided they are necessary for the operation of the device and for carrying out the process.

[0067] It may be provided that the first or finer fraction F1 of the second sieve 5 is subjected to thermal recycling, since dust, fine dust or mineral fractions cannot generally be recycled or fed into a recycling system.

[0068] Preferably, the second fraction, comprising coarser materials and generally also other foreign or impure substances, is fed from the outlet 14 to a further cleaning or screening device 7, in which the foreign and impure substances can be separated. This separation is preferably carried out within the housing or at least directly adjacent thereto. If an air classifier is used as the screening device 7, a cyclone 8 can be connected downstream. The cleaned fraction F2' can finally be fed to its own recycling device 17 or, as shown, preferably to the next larger fraction F3, in order to feed them together to the planned recycling, preferably in a recycling system.An exemplary utilization 17 in the case of waste wood recycling would be that pre-crushed starting material AM is fractionated and / or cleaned by the process or device, and in accordance with the requirements for the production of material boards, such as chipboard or fiberboard, is crushed in the utilization 17 to a predetermined grain size, glued in a subsequent gluing device, and pressed in a pressing device under pressure and temperature.

[0069] In an advantageous manner, the simple pre-cleaning or its fractionation enables a correspondingly effective utilization of the utilization 17 or the possibly necessary comminution 1644.

[0070] Reference symbol list 1644:

[0071] 1 device

[0072] 2 contaminant separators

[0073] 3 Sieve (first)

[0074] 4 Transfer facility

[0075] 5 Sieve (second)

[0076] 6 Transport direction

[0077] 7 viewing device

[0078] 8 Cyclone

[0079] 9 control flaps

[0080] 10 housings

[0081] 11 Entrance

[0082] 12 Outlet (EM)

[0083] 13 Outlet (F1)

[0084] 14 Outlet (F2)

[0085] 15 Outlet (F3)

[0086] 16 Outlet (F4)

[0087] 17 Recycling

[0088] B1 area

[0089] B2 area

[0090] B3 area

[0091] G Fall direction

[0092] AM starting material

[0093] EM ferrous metal

[0094] F0 Fraction

[0095] F1 faction

[0096] F2 faction

[0097] F2' fraction (purified)

[0098] F3 faction

[0099] F4 fraction (oversize)

Claims

Patent claims 1. Device for fractionating and / or purifying a material stream in a housing or vertical arrangement; 1.1 wherein, after an upper inlet (11) for the starting material (AM), several areas (B1, B2, B3) for separating different fractions (FO, F1, F2, F3, F4) from the starting material (AM) are arranged successively in the falling direction (G); 1.2 wherein in a first region (B1) in or after the inlet (11) a contaminant separator (2) for separating a first fraction (FO), preferably ferrous metal (EM), is arranged; 1.3 wherein a first sieve (3) for separating a second fraction (F4) of oversize particles is arranged in the second region (B2); 1.4 wherein a second sieve (5) is arranged below the first sieve (3) in a third region (B3) for separating at least a third fraction (F1, F2, F3) from the sieve passage of the first sieve (3); 1.5 wherein the two superimposed screens (3, 5) have a similar transport direction (6) for the material (M) on the screens (3, 5) and 1.6 wherein a transfer device (4) for at least partially transporting the sieve passage from the first sieve (3) counter to the transport direction (6) of the sieves (3, 5) is arranged between the two sieves (3, 5) and / or the second and third region (B2, B3).

2. Device according to claim 1, characterized in that at least one outlet (13, 14, 15, 16) of the fractions (F1, F2, F3, F4) a screening device (7) for separating a further fraction and / or for cleaning the fraction (F1, F2, F3, F4) is assigned.

3. Device according to at least one of the preceding claims, characterized in that a vibrating screen, a disc screen, a roller or roll screen, an air sifter and / or a throwing sifter is arranged as the first screen (3) and / or as the second screen (5).

4. Device according to at least one of the preceding claims, characterized in that a magnetic drum for metal separation, a non-ferrous metal separator, an eddy current separator, an air classifier, a sensor-based separation device and / or a heavy material separator is arranged as a contaminant separator (2) for separating the first fraction (FO).

5. Device according to at least one of the preceding claims, characterized in that a conveyor belt, a linear conveyor, a pneumatic conveyor, or guide plates inclined to the direction of fall (G) of the sieve passage are arranged as the transfer device (4).

6. Device according to at least one of claims 2 to 5, characterized in that the first sieve (3) and the second sieve (5) are arranged substantially directly below one another and preferably have a horizontal overlap of more than 50%, most preferably more than 75%.

7. Device according to at least one of the preceding claims, characterized in that at least the second sieve (5) is suitable for delivering different fractions (F1, F2, F3) along the transport direction (6), which are preferably directed to different outlets (13, 14, 15).

8. Device at least according to the preceding claim, characterized in that below the sieves (3, 5) at least one movable control flap (9) is arranged, preferably perpendicular to the transport direction (6), which is suitable for adjusting the ratios of the different fractions (F1, F2, F3) to one another or for adjusting the properties of the fractions (F1, F2, F3).

9. Device according to at least one of the preceding claims, characterized in that in the second region (B2) a disc screen, a roller screen or a star screen is arranged as the first screen (3) and in the third region (B3) a roller screen is arranged as the second screen (5).

10. Device according to claim 9, characterized in that a disc screen consists of rollers arranged parallel to one another, on which axially spaced discs are arranged and preferably the discs of the adjacent rollers mesh with one another and / or that a roller screen consists of rollers arranged parallel to one another, in which elevations are arranged on the surfaces and preferably these elevations mesh with the adjacent rollers or have a predetermined distance.

11. Device according to claim 9 or 10, characterized in that in the disc screen and / or the roller screen along the transport direction (6) a sifting effect from fine to coarse is arranged.

12. Device according to at least one of the preceding claims 9 to 11, characterized in that in one or more areas of the roller screen for screening a fraction, rollers with are arranged at substantially equal distances and / or elevations, and that preferably between two of these regions a larger distance is arranged for discharging a layer of the material lying on the rollers, wherein the layer adjacent to the rollers is enriched with large and / or heavy particles as well as other impurities and the distance between the regions is operatively connected to a separate outlet for discharging a separate fraction.

13. Device according to at least one of the preceding claims, characterized in that at least one outlet for discharging a fraction is operatively connected to a classifier or a heavy material separator for producing a subsequently cleaned fraction and is preferably combined with the fraction adjacent in terms of grain size.

14. Device according to at least one of the preceding claims, characterized in that at least one outlet for discharging a fraction, preferably with an outlet for an oversize grain of a sieve, is operatively connected to a comminution device for further utilization.

15. A method for classifying and / or cleaning a material flow in a housing or a vertical arrangement, wherein a starting material (AM) is fed to a housing (10) via an upper inlet (11) and successively passes through several regions (B1, B2, B3) for fractionation and / or cleaning in the direction of fall (G), wherein in a first region (B1) impurities are separated from the starting material (AM) as a first fraction (F0) and the remaining starting material (AM) passes through at least two sieves (3, 5) of the regions (B2, B3) arranged in the direction of fall (G), wherein each sieve (3, 5) separates at least one fraction (F1, F2, F3, F4) from the starting material, wherein the material is transported on the sieves (3, 5) in the same transport direction (6) and wherein the sieve passage between the first and the second sieve (3, 5) or the second and the third region (B2, B3) moves at least partially counter to the transport direction (6).

16. A method for processing pre-shredded waste wood, preferably according to the preceding method claim or in a device according to claim 1, characterized in that as starting material (AM) a pre-shredded waste wood or a comparable mixture with wood components is cleaned of ferrous metals (EM) in the first area (B1), in the second area (B2) it is screened with a disc screen, preferably classifying along the transport direction (6), and the oversize grain is discharged as fraction (F4) via a separate outlet (16) and in a third area (B3) below the second area (B2) in the same transport direction (6) the screening passes in the direction of fall onto a roller screen of the third area (B3) and is separated there into at least three fractions (F1, F2, F3) and fed to at least three separate outlets (13, 14, 15),wherein in the transport direction (6) the first fraction (F1) of the third region (B3) has a finer sieve passage than the other fractions (F2, F3) of the third region (B3), the second fraction (F2) of the third region (B3) comprises wood chips enriched with impurities and / or foreign substances, and the third fraction (F3) of the third region (B3) comprises pure usable wood chips.

17. Method according to one of claims 15 or 16, characterized in that at least the second fraction (F2) with the interfering and foreign substances for cleaning from the interfering and / or foreign substances, is passed through a screening device (7) and / or a cyclone (8) and preferably the cleaned fraction (F2') is fed to the material flow of the third fraction (F3) for further utilization, preferably further comminution.

18. Method according to one of claims 15 to 17, characterized in that the oversize grain of the first sieve (3) is fed to a comminution, wherein preferably the crushed oversize grain is fed again to the method and / or the device or the crushed oversize grain is fed to the third fraction (F3) of the third region (B3).

19. The method according to claim 16, characterized in that shredded or broken recycled wood with a grain size of up to 300 mm of a first edge length, up to 400 mm of a second edge length and up to 500 mm of the third edge length is used as the starting material (AM).

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