Plant and process for the production of glued plant particles

Abstract

Plant for the production of glued plant particles, in particular from annual plants, for the production of boards, e.g. fiberboard or chipboard, with at least one comminution device (2) for comminuting plant starting material into scatterable plant particles and with a gluing device (15) for gluing the plant particles, characterized by that between the comminution device (2) and the gluing device (15) at least one first screening device (3) for separating silicate particles from the plant particles is arranged, wherein the screening device (3, 14) is designed as an air sifter in which the supplied plant particles are exposed to an air stream, wherein silicate particles are removed with the air stream via an air outlet (6) to which an exhaust fan is connected, and the plant particles are collected and removed by gravity by at least one particle receptacle (8) arranged below the air outlet, wherein the air classifier has a material inlet (4) for supplying the plant particles, an air inlet (6) arranged below the material inlet (4), the air outlet (7) and the particle receptacle (8) arranged below the air outlet (7).

Description

The invention relates to a plant and a method for producing sized plant particles, in particular from annual plants (e.g. straw), for the production of boards, e.g. fibre boards or particle boards, having at least one comminution device for comminution of plant starting material to give spreadable plant particles and having a sizing device for sizing the plant particles.The vegetable starting material is lignocellulosic starting material, e.g. wood. However, it is particularly preferred to use lignocellulosic starting material from so-called annual plants, i.e. plants which require only one vegetation period from germination of the seed via the formation of the entire plant, flower formation, fertilization until the new seed has matured. Examples of such fast-growing plants are cereal plants (or the straw produced therefrom), for example rice or rice straw, but also bamboo, and bagasse, reed or pile tube. Spreadable particles from such plants or vegetable starting material are used in practice for the production of boards, for example particle boards or fibre boards, by sizing the spreadable plant particles with a binder or glue and subsequently pressing them in a press to form boards. In this case, annual plants (in particular straw resulting therefrom) are used as an advantageous alternative to conventional wood. Thus, for example, there is a need in classical agricultural cultivation, for example rice cultivation, to use the remaining straw after harvesting and not, as has been customary hitherto, to leave it on the fields or to combust it, but to use it for the production of fibreboards or particleboards. The possibility of producing material boards based on straw, for example ripping straw, is described, for example, in DE 10 2009 057 916 B4 and DE 10 2015 120 653 A1.In the course of the production of boards from vegetable starting material (wood or annual plants), suitable scattering particles (chips or fibers) are first produced and sized using comminution devices. Subsequently, particles of wood as well as particles of annual plants (e.g. straw) can be processed identically or in a very similar manner by scattering the (sized) particles onto a spreading belt conveyor, for example, with one or more scattering devices, forming a spreading material mat, and feeding them to a press, wherein the spreading material mat is pressed into a plate in the press using pressure and heat. The press may be a cycle press (e.g. a single-day or multiple-day press) or a continuous press.Overall, the use of annual plants, e.g. straw remaining therefrom, is a promising alternative to the use of wood for the production of fibreboards or particleboards. A problem in connection with the processing of particles from annual plants, for example rice straw, is the fact that annual plants incorporate high amounts of silicate during the growth, which is introduced into the production process and can interfere with the production process, since such mineral silicates can lead to high wear in various plant components due to their properties. For this reason, it has already been proposed, for example, in DE 10 2009 057 916 B4 to design components of a mixer for the sizing of fibers in a wear-resistant manner, since the silicates greatly stress the surfaces of the components.Furthermore, US 2003 / 0066168 A discloses a spreading device or forming station for the production of fiber boards, in which the already sized particles are spread from a bunker onto a forming belt, so that a mat is subsequently available for pressing. In this case, a air separator can be integrated into the forming station.Furthermore, DE 198 35 419 A1 discloses a device and a method for wind classification of lignocellulosic and / or cellulosic chips, fibers, mineral or similar parts mixed with at least one binder. The device comprises a metering unit, a scattering chamber, an air flow generating or supply unit and a diffuser with an inlet opening for the generated or supplied air flows into the scattering chamber.The object of the invention is to provide a plant and a method with which sized plant particles, in particular from annual plants, can be produced economically for the production of boards (e.g. fibre boards or particle boards). In particular, the problems arising from silicates should be reduced or minimized.To achieve this object, the invention teaches, in a generic plant for producing sized plant particles for the production of plates, that at least one first separating device, in particular a classifying device for separating (or separating) silicate particles from the plant particles or the plant particle stream, is arranged between the comminution device and the sizing device.The invention is based on the finding that boards, for example fiberboards or particle boards, can be produced not only economically with high quality from wood, but in particular also from annual plants which incorporate or absorb a high proportion of mineral silicates during growth. The invention has recognized that these silicates incorporated during growth can be separated or separated from the plant particles during the production of the glued plant particles which form the base material for the production of the plates, so that in particular wear problems in the plant components during the production of plates can be avoided and complex measures for improving the wear protection in the plants can be dispensed with. In addition, the quality of the sheets is considerably improved by reducing the silicate content. Silicates or silicate particles therefore mean, in the context of the invention, in particular the silicates / silicate particles incorporated into the plants or their fibers or cells during growth, which are released by comminution of the plants and / or by disruption of the fibers. Silicate particles preferably mean those having a diameter of less than 50 μm, preferably up to 20 μm.According to the invention, the classifying device for separating the silicate particles from the vegetable particle stream is designed as a wind separator. In this air separator, the supplied plant particles are exposed to an air stream (e.g. transverse stream), wherein silicate particles are discharged with the air stream via an air outlet and the plant particles (and possibly foreign bodies) are taken up by gravity by a particle receptacle arranged below the air outlet and discharged as product for further processing. The invention is based on the surprising finding that the silicates incorporated in vegetable material, e.g. straw or the like, can be effectively separated from the plant particles intended for further processing with the aid of a air separator. This is related inter alia to the fact that the silicates are present in the vegetable material, for example in straw particles or the like, in a relatively uniform size and shape, namely in a ball-like shape in the interior of the plant cells with a small diameter of generally less than 50 μm, for example about 5 μm to 20 μm, while the plant fiber particles intended for plate production are significantly larger. In the air separator, the silicate particles are reliably entrained by the air stream introduced into the classifier because of their small and substantially uniform size, so that they can be discharged with the air stream via an air outlet, while the remaining particles, i.e. in particular the plant particles intended for further processing, fall downward and can be taken up or discharged in a suitable particle receptacle. This separation is achieved with surprisingly high efficiency. This is also associated with the fact that the silicate particles, due to their very small (and uniform) dimension, form an aerosol together with the air stream, so that the silicate particles are reliably transported as solid suspended particles in the air stream (or another gas stream). The air (or other gas) thus forms a carrier gas for the silicate particles.The classifying device, which is designed as a wind separator, has an (upper) material inlet for the supply of the plant particles and an air inlet arranged below the material inlet. In addition, an air outlet is provided, via which the supplied air (or another gas) with the silicate particles is discharged. Below the air outlet, the particle receptacle for the plant particles intended for further processing is provided. The plant particles introduced from above via a material inlet into a classifier housing are consequently preferably acted upon with the air stream in a transverse flow. In principle, however, it is alternatively also possible to supply the classifying air from below and to operate it, for example, in an upward flow.Passive supply of supply air takes place by connecting an exhaust fan to the air outlet. In this case, it is possible to suck air, for example ambient air, into the classifier housing in a simple manner via the air inlet, wherein the air inlet can preferably be provided in a suitable manner with protective measures, for example a protective grille and / or a rain protector. Alternatively, it is also possible to circulate the air and consequently to return the air extracted (after appropriate separation of the silicates from the air / silicate mixture) to the region of the air inlet.In addition to the particle receptacle for the plant particles, the air separator in a preferred development has a coarse material receptacle which is likewise arranged below the air outlet and which is arranged upstream of the particle receptacle in the flow direction. Large and heavy foreign bodies, e.g. stones, which pass with the plant particles into the classifying device can be separated in this way and discharged via the coarse material receptacle, so that in this embodiment a separation into three fractions (coarse material / stones, plant particles, silicate particles) takes place.Of particular importance within the scope of the invention is the fact that during the processing of the vegetable starting material (e.g. the straw), the material is comminuted so that the chambers within the vegetable material in which the silicate particles are incorporated are broken up and release the silicate so that it can be separated in the described manner. In a particularly preferred development, the silicate separation takes place in two stages. This means that between the first classifying device (for a first silicate separation) and the gluing device a second comminution device is arranged, in which the plant particles are comminuted further, and that between this second comminution device and the gluing device a second classifying device (for a second silicate separation) is arranged.As a rule, it is expedient to process the starting material, for example straw, first in a coarse comminution device, for example in a straw shredder. This is then followed, for example, by the first comminution device already described, which can be designed, for example, as a mill, preferably as a hammer mill or the like. Already in this first comminution process or in these first comminution processes, a multiplicity of chambers in which silicates are contained are broken open, so that already after this first comminution, which can be carried out using a plurality of different comminution devices, a first silicate separation in the described manner is advantageous. In a preferred development, it is then particularly expedient to further break down the plant particles already roughly separated from silicate particles in a second comminution process. This is advantageous in particular when plant fibers for fiber boards, for example MDF boards, are to be produced. In this case, the second comminution device can be designed as a fiberizing device or fiberizing plant for producing plant particles which are designed as plant fibers. Such a fiberizing system has, in particular, a refiner in which the chip-like particles are broken down into fibers in a manner known in principle. In the course of this fiberizing, the wood cells or plant cells in which the silicate particles are incorporated are broken up further or completely, so that in this second stage silicates are (again) released, which are subsequently separated in the second classifying device. Of interest in this case is the fact that the first classifying device and the second classifying device can be adapted to the respective circumstances and in particular to the particle properties with regard to dimensioning and flow properties, so that particularly efficient silicate separation is possible in two stages. This two-stage procedure is particularly advantageous in the production of plant fibers for the production of fiber boards, for example MDF boards. The two-stage separation of silicate particles can, however, also be expedient in the production of straw chips or the like for particle board production if no fiberization takes place in a refiner or the like. Multistage comminution is also expedient in the production of chips, so that the second comminution device can then be designed, for example, as a suitable mill, so that the second comminution can take place in a grinding process.Also in the production of fibers, the second comminution device can be designed not as a refiner but alternatively mechanically, for example as a mill.The preferably provided second viewing device can basically be designed in the same manner as the described first viewing device. If necessary, it can be expedient to provide a separation into three fractions (including the separation of foreign bodies) in the first classifying device and merely a separation into two fractions in the second classifying device, so that there, for example, an additional coarse material receptacle as a "stone trap" can be dispensed with.As described, the first and / or second viewing device is preferably equipped with a particle receptacle, for example for plant particles. Optionally, a plurality of particle receptacles arranged one behind the other (in the flow direction) or a particle receptacle having a plurality of receptacle zones arranged one behind the other can also be provided. This configuration has the advantage that optionally a division (of the plant particles) into a plurality of (useful) fractions is possible. In an advantageous development, it can be provided that the location and / or length (along the flow direction) of one or more particle receptacles or receptacle zones (variable) is / are adjustable, namely during assembly and / or during startup and / or during operation. This can be realized, for example, by means of adjustable guide plates in the region of the particle receptacles.The vision device, which functions as a wind vision device in the described manner, has a housing which can be designed, for example, in a very simple configuration as a box-shaped housing. Such a box-shaped housing can have the shape of a rectangular block or the like, for example, wherein preferably at least the material inlet and the air inlet extend over (substantially) the entire width of the housing. The material inlet can be integrated, for example, into the (upper) ceiling of the box-shaped housing, namely in the front region of the ceiling with respect to the flow direction, so that the material falls into the box-shaped housing from above. The air inlet can be integrated in a very simple embodiment into the front wall of the housing, namely for example in the upper region of the front wall. The air outlet can be integrated, for example, into the rear wall opposite the front wall or can be arranged in the region of the rear wall, specifically likewise, for example, in the upper region of this rear wall. This means that the air stream with the silicate particles flows through the housing substantially in the upper region, while the plant particles and optionally the stones or similar coarse material fall downward out of the air stream. The particle receptacle and / or the coarse material receptacle is / are consequently arranged in the vicinity of the bottom of the box-shaped housing, such that the plant particles and / or the coarse material are received in the lower region of the box-shaped housing. From there, it can be discharged downwardly or also laterally from the housing. In the material inlet, which can be formed by a fall shaft, for example, or can be connected to such a shaft, rollers, for example, opening rollers, can be integrated, in order to open up the material to be introduced, for example. Otherwise, the material can be divided in this way at the inlet, so that a plurality of "curtains" are produced from the particles. In addition, it is possible to provide feed devices, feed screws in the region of the material inlet. A discharge device can be integrated into the particle receptacle, which is arranged e.g. in the lower region of the housing, or a discharge device can be connected to this particle receptacle, which can have e.g. one or more discharge worms. Alternatively, other discharge devices, e.g. conveyor belts or the like, are also possible, but discharge worms have the advantage that they are substantially (gas-)tight, so that further cell wheel locks or the like can be dispensed with. In order to produce a gas-tight chamber bottom of the separator, a cellular wheel sluice can additionally be provided.A viewing device is distinguished by a particularly simple construction and a particularly economical transport, the (box-shaped) housing of which is produced from one or more ISO freight containers. Thus, the housing can be produced, for example, from a plurality of standard containers, for example two or three standard containers arranged one above the other, wherein these are preferably 40 ft. standard containers, which can also be designed, for example, as high-cube containers. The width and the length of the classifier housing are defined in this case by the width and length of the standard containers. The invention is based on the surprising knowledge that, despite such a simple construction, silicate particles can be separated economically from the particle stream with high efficiency. The housing can be transported in the form of cargo containers, as it were, modular to the place of use and can be completed there. The housing or the containers can then (subsequently) be equipped with conventional maintenance platforms or the like, which are set up and / or fastened on the outside of the containers, for example.The plant particles freed of silicate particles in the manner described are provided with a binder for further processing in the sizing device and are consequently sized. Such a gluing device can be designed in a fundamentally known manner. Preferably, a gluing device is used which is designed as a drum mixer and which is described, for example, in DE 10 2009 057 916 B4. This is a continuously operating mixing device which has a mixing chamber and one or more mixing tools fastened to a rotating mixer shaft, wherein the mixing tools mix the particles, for example fibers, with the binder and convey them through the mixing chamber in a conveying direction. Such a mixing device can preferably be operated with particularly high centrifugal acceleration. This means that the rotational speed of the mixer shaft and the diameter of the mixing chamber are matched to one another with the proviso that the (nominal) centrifugal acceleration of the fibers in the region of the mixing chamber jacket is from 10,000 to 30,000 m / s 2. In detail, with regard to the design and operating mode, reference is made to DE 10 2009 057 916 B4.The described plant relates to the production of the sized plant particles, e.g. sized fibres or chips, which are particularly intended for the production of fibreboards or particleboards. The production of the sized plant particles is thus protected (without the subsequent pressing process). However, the invention also relates to a plant for producing boards, for example particle boards or fibre boards, from such sized plant particles. Such a plant for producing sheets consequently comprises, on the one hand, the plant for producing the glued plant particles already described and, in addition, at least one spreading device, which is arranged downstream of the gluing device and is used to produce a mat of spreading material from the glued plant particles, and a press, which is arranged downstream of the spreading device and in which the mat of spreading material is pressed to form a sheet under the application of pressure and / or heat. According to the invention, therefore, not only is the plant for producing the sized plant particles protected, but also the overall plant for producing the plates, which additionally comprises in particular one or more scattering devices and at least one press. The press can be a cycle press, for example a single-day press or multi-day press. The press is preferably a continuously operating press, which can be designed, for example, as a double belt press in the embodiment, wherein such a double belt press has an upper press plate and a lower press plate and, in the upper press part and in the lower press part, continuously circulating press belts, for example steel belts, are supported on the press plates with the interposition of rolling element assemblies, for example rolling rods, wherein the upper press plate and / or the lower press plate is / are acted upon by press cylinders.The invention furthermore relates not only to the described plants but also to a method for producing sheets from plant particles, e.g. from plant fibers or plant chips, having a plant of the described type, wherein plant particles are produced by comminution from plant starting material, in particular from annual plants (e.g. straw), and these are subsequently sized, wherein a scattering material mat is produced from the sized plant particles and this is pressed in a press to form a sheet. This method is characterized in that, after crushing the starting material, silicate particles are separated from the plant particles or the particle stream before the sizing. The method is particularly preferably configured in two stages, so that silicate particles are separated from the particle stream on the one hand after a first comminution and on the other hand after a second comminution, e.g. fiberizing.The described plant and the described method can be used in principle for the processing of plant particles from wood and consequently for the processing of wood fibers or wood chips. Particularly preferably, the processing of plant particles from annual plants, e.g. from straw or the like, which remains after a threshing process of a plant, e.g. as a rice straw, is carried out. According to the invention, a particularly effective use of this straw can be effected in the course of the production of fibre boards or particle boards, namely on account of the described precipitation of the silicate components and the avoidance of the problems observed hitherto in the processing of such materials.The invention is explained in more detail below with reference to the drawings which merely represent exemplary embodiments. They show FIG. 1 shows a greatly simplified schematic illustration of an installation (or a method) for producing sheets from glued plant particles, FIG. 2 shows a view of a viewing device of the system according to FIG. 1 in a side view, FIG. 3 shows the viewing device according to FIG. 2 in a front view. FIG. 4 is a plan view of the object according to FIG. 2, FIG. 5 is a section A through the article according to FIG. 3 with indicated flow conditions.FIG. 1 shows a plant with which sized plant particles, for example sized fibers from annual plants, for example from straw and particularly preferably rice straw, are produced and these are pressed to form sheets.The straw provided as starting material M is comminuted after pre-comminution in, for example, a straw chopper 1 in a first comminution device 2 which is designed as a hammer mill 2 in the exemplary embodiment. The material produced in this first comminution device 2 is fed to a first classifying device 3 which forms a first classifying stage for separating silicate particles from the straw particles. This first viewing device 3 is shown on an enlarged scale in FIGS. 2 to 5, which will be discussed in more detail below.In such a classifying device 3, which is designed as a wind classifier, the straw particles are introduced into the classifier housing 5 via an upper material inlet 4 and are subjected to an air stream (supply air Z) in the classifier housing. For this purpose, the separator 3 has a front, upper air inlet 6 and a rear, upper air outlet 7. Below the air outlet 7, a particle receptacle 8 for the straw particles P freed of silicate S is provided. Arranged upstream of the particle receptacle 8 in the flow direction is a coarse material receptacle 9 for receiving foreign bodies, e.g. stones or similar coarse material G. In this classifying device, the silicate particles S are entrained by the air stream and discharged via the air outlet 7 due to their very small and uniform size, while the plant particles, e.g. straw particles P, intended for further processing pass into the region of the particle receptacle 8 due to gravity and are discharged therefrom. In principle, it is possible to feed the straw particles freed of silicate in this way to a gluing device and then press the glued particles into a plate in a press after forming a scattering material mat. In the exemplary embodiment shown, however, the straw particles freed of silicate in the first classifying stage are fed in a further step-possibly after intermediate storage in a bunker 13-to a second comminution device 10. This second comminution device is designed in the embodiment as a defibrating device in which straw fibers are produced from the straw particles for the production of fiber boards. This fiberizing device 10 can have, in a fundamentally known manner, a digester 11 which is merely indicated and in which the particles are softened, for example with steam overpressure. This is followed in a generally known manner by a refiner 12 in which the softened particles are milled to fibers. The fibers ground in this way do not pass, for example via a blowline (not shown) after appropriate drying in the embodiment shown, directly into the region of a glue application device, but before the glue application, silicate particles are again separated from the straw particles or the straw fibers now produced in a second classifying device 14.In this case, it is always possible to divide the particle stream into a plurality of parallel partial streams and consequently to operate with a plurality of parallel viewing devices. In the figures, only one viewing device is shown by way of example. The second viewing device 14, which is merely indicated in FIG. 1, is again designed as a wind separator. It is basically constructed in the same way and functions in the same way as the first classifying device 3 already described, wherein the coarse material receptacle or stone trap can be omitted if necessary in the region of the second classifying device. In any case, in this second stage of vision, silicate particles S are again discharged via an air outlet 7 and disposed of or used for other processes. The straw fibers P freed of silicate S are again discharged via the particle receptacle 8 and, if appropriate after intermediate storage in a bunker 20, are fed to a gluer 15. Here too, a plurality of gluing devices can be provided for parallel operation; in the drawing, a gluing device 15 is shown merely by way of example. This gluing device 15 is designed in the exemplary embodiment as a gluing mixer, the construction and functioning of which corresponds to the mixing device described in DE 10 2009 057 916 B4. This sizing mixer is used, for example, to size the straw fibers with an isocyanate or another size.The sized straw fibers produced in this way and freed from silicate are now available for the production of fiber boards. For this purpose, they are fed to a spreading device 22, for example via a fiber separator 21, in which lumps of glue or the like are separated. With this spreading device 22, the sized straw fibers are spread onto a spreading belt conveyor 23, for example, to form a spreading material mat, and from there, optionally after a further pretreatment, for example in a pre-press 24, they pass into a hot press 25, in which the spreading material mat of sized straw fibers is pressed to form a fiber plate. The press 25 can be, for example, a continuously operating press 25 in the embodiment as a twin-belt press.The classifying device 3 or 14 is of particular importance according to the invention for separating silicate particles from the particle stream of straw particles or straw fibers. This viewing device is shown in FIGS. 2 and 5.The viewing device 3 or 14 is designed as a wind separator. In the exemplary embodiment, this has a box-shaped housing 5 with the material inlet 4, the air inlet 6, the air outlet 7 and the particle receptacle 8 and the coarse material receptacle 9. Connected to the material inlet 4 is an upper fall shaft 16, in which opening rollers 17 are arranged. Furthermore, feed worms 18 are indicated, via which the respective material is fed to the material inlet 4. The material inlet 4 extends substantially over the entire width of the classifier housing 5, wherein in the illustrated exemplary embodiment the material inlet 4 is integrated into the upper ceiling of the classifier housing, so that the material falls into the classifier housing from above. The air inlet 6 is integrated into the front wall of the classifier housing in the upper region. This air inlet 6 can also extend over the entire width of the classifier housing 5. The air outlet 7 is arranged in the region of the rear rear wall of the classifier housing, wherein the latter likewise extends over the entire width of the classifier housing and then merges into at least one outlet line 27 with a reduced diameter, wherein the disruptive silicate particles S are discharged with the air stream via this line or lines 27. In the region of the lower particle receptacle 8, discharge worms 29 are provided in the exemplary embodiment, with which the straw particles P freed of silicate are discharged and fed to discharge lines.In FIG. 5, the flow conditions in the classifier are shown. It can be seen that the silicate particles S, because of their small dimension, are discharged in the manner of an aerosol with the air flow via the upper air outlet 7, while the straw particles P fall down due to gravity and fall into the region of the particle receptacle 8. Coarse material G, for example stones, immediately after entering the housing 5 fall into the region of the coarse material receptacle 9, which is also referred to as a "stone trap".In the exemplary embodiment, the flow within the separator is realized by means of suction, i.e. suction fans are respectively connected to the air outlet, so that the supply air Z is supplied passively via the air inlet 6. In the exemplary embodiment shown, fresh air is supplied in the first classifying stage, while in the second classifying stage the classifying air is guided in the circuit (not shown), so that the moisture can be kept constant in this stage of the process after fiberizing.It can be seen in FIGS. 2 to 4 that the classifier housing in the embodiment shown is manufactured in a very simple manner from a plurality of ISO freight containers, namely from three standard containers 28 arranged one above the other and each having a length of 40 ft. Such a construction has the great advantage that simple transport of the individual components can take place.The air inlet 6 can be realized very easily, for example, by opened container doors. A grid or the like can be integrated into the inlet in order to prevent the penetration of foreign bodies. Moreover, a rain protector 26 may be disposed above the inlet 6.

Claims

Plant for producing sized plant particles, in particular from annual plants, for producing boards, e.g. fibre boards or particle boards, having at least one comminution device (2) for comminution of plant starting material to give spreadable plant particles and having a sizing device (15) for sizing the plant particles, characterized in that at least one first classifying device (3) for separating silicate particles from the plant particles is arranged between the comminution device (2) and the sizing device (15), wherein the classifying device (3, 14) is designed as a wind classifier in which the supplied plant particles are acted upon by an air stream, wherein silicate particles are acted upon by the air stream via an air outlet (6) to which an extraction fan is connected, and the plant particles are taken up and discharged by at least one particle receptacle (8) arranged below the air outlet due to gravity, wherein the air separator has a material inlet (4) for supplying the plant particles, an air inlet (6) arranged below the material inlet (4), the air outlet (7) and the particle receptacle (8) arranged below the air outlet (7).Plant according to claim 1, characterised in that between the first screening device (3) and the sizing device (15) a second comminution device (10) is arranged, in which the plant particles are comminuted further, and in that between the second comminution device (10) and the sizing device (15) a second screening device (14) is arranged for separating silicate particles from the plant particles.Plant according to claim 1 or 2, characterised in that the air separator has, in addition to the particle receptacle (8), a coarse material receptacle (9) for foreign bodies arranged upstream thereof in the flow direction.Plant according to one of claims 2 or 3, characterised in that the second comminution device (10) is designed as a defibering device with a refiner (12) for producing plant particles designed as plant fibres.Plant according to one of claims 1 to 4, characterised in that the viewing device (3, 14) has a box-shaped housing (5), wherein the material inlet (4) and / or the air inlet (6) and / or the air outlet (7) extends or extend over the entire width of the housing (5).Plant according to one of claims 1 to 5, characterised in that opening rollers (17) are arranged in the material inlet or in a drop shaft (16) connected thereto and / or that a discharge device (29) is integrated into the particle receptacle (8) or connected thereto, which has, for example, one or more discharge worms (29).Installation according to one of Claims 1 to 6, characterized in that the classifier housing (5) is formed by a plurality of standard freight containers (28) arranged one above the other.Plant according to one of Claims 1 to 7, characterized in that the glue application device (15) has a drum mixer or is designed as a drum mixer.Plant for producing sheets from plant particles, in particular for producing fibre sheets or particle boards, having a plant for producing sized plant particles according to one of Claims 1 to 8 and having a spreading device (22), arranged downstream of the sizing device (15), for producing a granular material mat from the sized plant particles and having a press (25), arranged downstream of the spreading device (22), in which the granular material mat is pressed to form a sheet.Method for producing sheets of plant particles with a plant according to Claim 9, wherein plant particles are produced from plant starting material, in particular from annual plants, by comminution and these are subsequently sized, wherein a scattering material mat is produced from the sized plant particles and this is pressed in a press to form a sheet, characterized in that, after comminution of the starting material, silicate particles are separated from the plant particles before the sizing.Method according to claim 10, characterised in that silicate particles are separated from the particle stream in two stages, on the one hand after a first comminution and on the other hand after a second comminution, e.g. fiberisation.

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