Screening machine

Abstract

The present invention relates to vibrating screening machines that comprise a flat screening grid (2) situated in a plane inclined at a non-zero angle with respect to the horizontal, a device for feeding material to be screened positioned at the top end of the grid, a vibration generator designed to transmit vibrations to the grid, wherein the specific configuration of the metal wires (5) making up the grid allows easy cleaning, in particular when the materials to be screened include fibrous materials. The present invention also relates to screening grids for vibrating screening machines, to installations for treating waste that comprise such machines, and to methods for treating waste that employ said machines.

Description

[0001] The present invention relates to screening machines, particularly for screening waste containing fibrous materials, and to methods employing such screens. More specifically, the present invention relates to machines for screening waste containing sticky and moist fibrous materials, such as organic matter mixed with unwanted materials, including metals, minerals, plastics, and glass, and to methods for treating said waste using such screens.

[0002] Waste treatment processes for energy recovery and / or material recovery are constantly evolving.

[0003] Among the waste treatment processes for energy and material recovery, we can mention in particular methanization processes, which aim to produce biogas, and composting processes applied after methanization or directly to fresh household waste containing organic matter. The raw material for these processes can be waste from selective collection, green waste, kitchen waste, or even waste from the agri-food industry, or even household waste from non-selective collection containing different categories of materials, such as putrescible waste (food waste, green waste), paper, cardboard, glass, plastic, ferrous or non-ferrous metals, fabrics, sanitary textiles, and possibly dispersed hazardous household waste (batteries, etc.).

[0004] For example, the methanization and / or composting of household waste to transform it into biogas and / or usable compost involves three to four main steps: Mechanical waste preparation aims to separate biodegradable organic matter from other fractions that cannot be used for biogas or compost. This step may include various grinding and / or screening processes, as well as passing the waste through a rotating pre-fermentation tube, generally horizontal, which serves as a means for such preparation. In particular, the treatment of unsorted household waste requires one or more screening and ballistic separation operations. These operations allow for sorting materials according to their particle size and density, and for separating biodegradable organic matter from other fractions that cannot be used for biogas or compost, whether these fractions are light (plastic films, hard plastics, etc.) or heavy (glass, pebbles, metals, etc.).Anaerobic digestion, which aims to produce renewable energy and is carried out in horizontal or vertical chambers, mechanically agitated or not; composting of the fresh fraction from the pretreatment of household waste, or aerobic maturation of the digestate, which generally involves a preliminary pressing operation of the digestate from anaerobic digestion, in order to reach a level of dry matter content and porosity allowing the digestate to self-compost, or which requires the addition of a structuring agent and its mixing with the digestate to obtain a compostable substrate; final refining, which aims to further remove the contaminants remaining after the two previous operations, and to prepare the compost to a particle size allowing its agronomic valorization.

[0005] Among the waste treatment processes for energy recovery, we can also mention the production of Solid Recovered Fuels (SRF), from dry waste with high calorific value (wood, chlorine-free plastics, paper, cardboard, and wood), which are sorted, shredded, and refined to obtain a particle size fraction suitable for the intended use. The raw materials for these processes can be residual household waste (RHW), ordinary industrial waste (OIW), and bulky waste from recycling centers of heterogeneous quality or too large to be processed in energy recovery units (incineration and co-incineration).

[0006] All these processes involve one or more sorting, and / or crushing, and / or screening operations. In particular, at various stages of waste treatment processes, it is desirable to implement fine screening using a fine sieve mesh.

[0007] In biogas production processes, fine screening using a fine mesh allows, during the mechanical preparation phase preceding the actual biogas production, for the optimization of organic matter collection. This organic matter, which can be used for biogas production and composting, concentrates in the fine fraction, particularly after passing through a rotating pre-fermentation tube. Typically, this fine screening should allow for the recovery of a waste fraction smaller than 5 millimeters, in which the organic matter suitable for biogas production and composting is concentrated.

[0008] Fine screening therefore makes it possible to select the materials to be treated according to their particle size and to separate degradable organic matter and mineral matter.

[0009] Similarly, fine or even very fine screening is useful for calibrating RDF (Refuse Derived Fuels) and SRF (Solid Recovered Fuels), which are produced by shredding the light, coarse fraction from household waste and / or dry, high-calorific-value waste, including plastics, wood, composite wood, automotive shredder rejects, and textiles, from which the goal is to remove the fines. Removing the fines is essential because they generally contain components with a low calorific value and / or higher moisture content, and because it prevents soot formation during fuel use.

[0010] However, in both of these processes, it is difficult to use fine-mesh screens without encountering clogging problems, particularly when collecting valuable organic fractions, which may contain wet, sticky, or fibrous materials, or when the screen mesh is very fine. Regardless of the configuration, this clogging is detrimental in terms of the quantity (organic matter) or quality (RDF, CSR) of the recovered valuable fractions.

[0011] For methanization treatments, existing devices use relatively large mesh sizes to avoid the loss of organic matter but do not offer the selectivity necessary for its purification, or also offer self-cleaning screens or screens incorporating periodic cleaning systems.

[0012] Patent EP 1 957 210 discloses a "flip-flop" screening machine, also known as a trampoline-effect screen or tension wave screening machine. This equipment features a screening surface inclined at approximately 20° to the horizontal, made of a flexible synthetic mesh with closed openings. This mesh is repeatedly stretched and released by motorized crossbars to which it is attached. These high-frequency movements generate an acceleration of several tens of "g" forces on the objects present on the screening mesh, dislodging them and thus clearing the blockage. However, it is necessary to periodically wash these meshes with high-pressure water, which leads to problems with immobilization and the management of cleaning water, as well as risks of weakening or even perforation of the mesh.

[0013] The lifespan of the flexible synthetic (especially polyurethane) screens used in these screens is limited: they are particularly susceptible to tearing due to the presence of abrasive materials in the screened waste.

[0014] Application EP2 364 782 discloses the use of trampoline-effect screens for screening wet organic matter, with mesh sizes of 10 millimeters. This application also mentions risks of chemical attack on these screens when relatively wet organic waste is screened.

[0015] Generally, the mesh of these screens can consist of slits, square, rectangular, or round openings. Their dimensions typically range from 8 to 12 millimeters for wet household waste. With these devices, it seems difficult to screen waste containing wet organic matter with a mesh size smaller than 10 mm without clogging the screens. In all cases, the mesh opening expands and contracts with the movement of the screen, which can lead to quality issues.

[0016] Documents DE 17 81 264, US 2011 / 220555 describe a sieve or grid, made of metal wires located in the same plane, and having bends or undulations.

[0017] US document 5,219,078 describes a separation machine comprising separation combs made of vibrating wires.

[0018] Alternatively, application WO2015 001514 discloses a screening machine according to the preamble of claim 1.

[0019] However, in practice, it has been observed on the type of screen described in application WO2015 001514 that cleaning the lower surface of the grid can be ineffective under certain conditions and that as a result these grids become clogged, particularly when used to screen waste containing fibrous organic matter, especially wet and sticky.

[0020] Therefore, there is a need for waste screening systems that use a fine sieve mesh and prevent clogging problems. In particular, there is a need for such systems that also have an extended lifespan, minimizing downtime and maintenance issues.

[0021] The present invention relates to a vibrating screening machine according to claim 1.

[0022] The present invention also relates to waste treatment installations comprising vibrating screening machines with screening grids, and to waste treatment processes implementing said machines.

[0023] The invention also relates to an automatic brushing system deployed on the upper face of the grid, which ensures the cleaning of its upper and lower faces.

[0024] The screens of the screening machines according to the invention, thanks to their specific configuration and the specific diameter of the metal wires that compose them, exhibit a flexibility that allows the brushes to pass through the screen to clean its underside, thus preventing the accumulation of material on this underside and avoiding clogging. The specific configuration of the metal wires constituting the screen of the machines according to the invention therefore allows for easy cleaning, particularly when the materials to be screened contain fibrous materials, especially wet or sticky fibrous materials.

[0025] Furthermore, these wire diameters are large enough to maintain a grid strength suitable for its use, and thin enough to allow an optimal passing area / overall grid area ratio.

[0026] Advantageously, the diameter of the wires of the screens of the screening machines according to the invention are between 1 and 1.7 millimeters, preferably between 1.1 and 1.6 millimeters, or between 1.2 and 1.6 millimeters, or between 1.3 and 1.6 millimeters, or between 1.4 and 1.5 millimeters.

[0027] For the purposes of the present invention, screening means an operation of separating a particulate material into two particle size fractions by passing it through a grid or sieve comprising openings or meshes of a determined size.

[0028] For the purposes of this invention, a longitudinal wire is defined as a wire that extends lengthwise in a straight line. The longitudinal wires of the grid according to the invention are not perfectly straight and may have patterns (arcs, crenellations, triangular patterns, etc.) distributed on either side of this straight line.

[0029] For the purposes of the present invention, longitudinal wires substantially in the same direction are understood to mean wires whose directions have a maximum angle between 0 and 5 degrees relative to each other.

[0030] For the purposes of the present invention, the minimum non-zero distance between a wire and its neighbors means, in particular, the fact that the wires constituting the grids according to the invention are not joined together, for example not welded or woven together, even if, taking into account deformations, wires near the grid may have some non-permanent points of contact between them.

[0031] In the screening machines according to the invention, the material to be screened flows over the screen from end (E1) to end (E2) of the screen, following a substantially straight direction.

[0032] Typically, in screening machines according to the invention, the screens are mounted on a rigid frame (1). The ends (E1) and (E2) of the screen are typically attached to tensioning systems (3) allowing it to be kept substantially flat.

[0033] Typically, the crossbars (6) of the grids are rubber strips. The grids according to the invention may also have a rubber strip on their outer edges, facilitating clamping onto the frame (1).

[0034] According to one embodiment, the grids of the vibrating screening machines according to the invention are located in an inclined plane at an angle α with respect to the horizontal of between 30° and 60°, preferably between 40 and 45°. Typically, this angle is 42°.

[0035] According to one embodiment, the vibration generator of the screening machines according to the invention comprises at least one electromagnetic hammer (4) positioned to strike at least one crossbar (6).

[0036] According to the invention, the vibrating screening machines according to the invention comprise a brushing means (9, 10) capable of exerting a back-and-forth movement on the screen (2).

[0037] According to the invention, said brushing means comprises at least one cylindrical brush (10) with an axis substantially parallel to the at least one transverse bar (6).

[0038] For the purposes of the present invention, substantially parallel means two lines which have an angle between them of between 0 and 5 degrees.

[0039] According to one embodiment, the diameter of said cylindrical brushes (10) is between 500 and 700 millimeters.

[0040] According to the invention, said cylindrical brushes (10) comprise bristles with a diameter between 0.4 and 1.0 millimeters.

[0041] Typically, said cylindrical brushes (10) are mounted on a movable frame (8, 9).

[0042] Advantageously, in the vibrating screening machines according to the invention, the grids (2) are made of metal wires (5) having a substantially sinusoidal profile in the plane of said grid (2).

[0043] For the purposes of this invention, a substantially sinusoidal profile is defined as a profile that closely resembles a sinusoid, that is, composed of arcs similar to those of a sinusoid, with the same amplitude and period, regularly distributed on either side of a straight line that coincides with the direction of the longitudinal wires. The sinusoidal nature of the profile is not affected by localized deformations that may exist on the wire.

[0044] In the vibrating screening machines according to the invention, the mesh L of the grid (2) is between 5 and 12 millimeters, preferably between 6 and 10 millimeters, preferably between 7 and 9 millimeters.

[0045] The mesh size L of the grid is defined as the maximum average distance between consecutive longitudinal wires of the grid, along a direction orthogonal to the direction of said longitudinal wires. For example, for a grid comprising wires with a sinusoidal profile, the mesh size L represents approximately twice the amplitude of the sinusoid.

[0046] Advantageously, in the vibrating screening machines according to the invention, the mesh L of the grid (2) is between 7 and 9 millimeters and the diameter of the wires of the grid (2) is between 1 and 1.7 millimeters.

[0047] In vibrating screening machines according to the invention, the mesh L of the grid (2) is between 1 and 4 millimeters, preferably between 1.5 and 3.5 millimeters, preferably between 2 and 3 millimeters.

[0048] Planar screening grids (2) for vibrating screening machines as described above are also described, grids comprising a series of metal wires (5) extending substantially in the same longitudinal direction, the metal wires (5) all being located in the plane of the grid, the distance between a metal wire (5) and its neighboring wires varying between a maximum and a minimum, the minimum distance being non-zero, characterized in that: the diameter of the metal wires (5) is between 1 and 1.7 millimeters, the mesh L of the grid (2) is between 7 and 9 millimeters, the grid includes at least one crossbar (6), arranged perpendicular to the direction of the longitudinal wires (5).

[0049] Typically, the grids described are made with stainless steel wires. Typically, the transverse strips (6) of the grids according to the invention are made of rubber.

[0050] According to one method of description, the metal wires (5) have a substantially sinusoidal profile in the plane of the grid.

[0051] The present invention also relates to waste treatment installations comprising at least one vibrating screening machine as described above.

[0052] The present invention also relates to waste treatment processes comprising at least one step of vibrating screening of materials from / derived from waste on a vibrating screening machine as described above, said step comprising vibrating the screen (2) by a vibration generator positioned to transmit said vibrations to the screen (2) via at least one crossbar (6).

[0053] According to one embodiment, in the processes according to the invention, all or part of the materials from at least one vibrating screening step are subjected to a treatment enabling their energy recovery and / or material recovery.

[0054] Materials from at least one vibrating screening stage include both materials that have passed through the screen (2) and the screening rejects that remain above the screen (2).

[0055] In a particular embodiment, in the processes according to the invention, the waste contains organic matter mixed with undesirable materials, including metals, minerals, plastics, glass, and said processes comprise: at least one vibrating screening step carried out on a machine according to one of claims 1 to 9, said machine comprising a screen (2) having a mesh L of between 6 and 10 millimeters, preferably between 7 and 9 millimeters, and, optionally, one or more grinding and / or screening steps allowing the particle size of the waste intended to feed the vibrating screening step to be reduced to a dimension of less than 30 millimeters, preferably less than 20 millimeters.

[0056] In this embodiment, waste containing organic matter may be unsorted waste, for example, unsorted household waste. Alternatively, this waste may originate from sorted household waste or other sources and contain a significant fraction of organic matter associated with undesirable elements. These undesirable elements include, for example, packaging contaminated with organic matter.

[0057] These wastes generally have a high moisture content, typically between 50 and 80%, and contain a large amount of sticky and / or fibrous material (kitchen waste, restaurant waste, unsold supermarket goods...).

[0058] In particular, in this embodiment of the processes according to the invention, the waste having passed through at least one vibrating screening stage can be subjected to methanation treatment in a digester.

[0059] In particular, in this embodiment of the processes according to the invention, at least one vibrating screening step may be preceded by a pre-fermentation treatment in a rotating tube with feeding at one end and extraction at the other end.

[0060] The present invention relates in particular to methods for treating waste, especially household waste, containing organic matter mixed with undesirable materials, including metals, minerals, plastics, and glass, in which: The waste is subjected to a first sorting by screening, the fraction of waste passing through the screen is subjected to a pre-fermentation treatment in a rotating tube with feeding at one end and extraction at the other end, the waste from the pre-fermentation treatment is subjected to one or more grinding and / or screening stages allowing its particle size to be reduced to a dimension of less than 30 millimeters, preferably less than 20 millimeters.said fraction of waste with dimensions less than 30 millimeters, preferably less than 20 millimeters, is subjected to at least one vibrating screening stage carried out on a machine as described above, said machine comprising a screen (2) with a mesh size L between 6 and 10 millimeters, preferably between 7 and 9 millimeters, at least part of the material having passed through the vibrating screening stage is subjected to energy recovery and / or material recovery treatment, preferably methanation treatment in a digester.

[0061] The present invention also relates to installations for implementing the processes described above, and comprising: at least one vibrating screening machine as described above, said machine comprising a screen (2) having a mesh size L between 6 and 10 millimeters, preferably between 7 and 9 millimeters, one or more grinding and / or screening devices enabling the reduction of the particle size of the waste intended to feed the vibrating screening machine to a dimension less than 30 millimeters, preferably less than 20 millimeters.

[0062] In particular, the installations according to the invention include at least one rotating pre-fermentation tube.

[0063] According to one variant, the processes according to the invention are waste treatment processes where the waste is dry waste with a high lower calorific value, and comprising: one or more fine grinding stages allowing the particle size of the waste to be reduced to a dimension less than 30 millimeters, preferably less than 20 millimeters, followed by at least one vibrating screening stage carried out on a machine as described above, said machine comprising a screen (2) having a mesh size L between 1 and 4 millimeters, preferably between 1.5 and 3.5 millimeters, preferably between 2 and 3 millimeters.

[0064] In this embodiment, dry waste with a high lower calorific value includes, in particular, plastics, wood, composite wood, automotive shredding rejects, and synthetic textiles.

[0065] Dry waste is defined as waste with a moisture content of less than 25%, or 20%, or 10%, typically between 25% and 5%. High lower heating value (LHV) is defined as a lower heating value typically between 12 and 18 MJ / kg.

[0066] Advantageously, in this embodiment, the processes according to the invention include, upstream of the fine grinding stage, one or more coarse grinding stages enabling the reduction of the particle size of the waste to a dimension less than 300 millimeters, preferably less than 200 millimeters.

[0067] Finally, the use of materials constituting the rejection of vibrating screening of processes as described above as solid recovered fuels is also described.

[0068] Solid recovered fuels typically refer to fuels known as "SRF" or "RDF" (refuse derived fuel).

[0069] Other features and advantages of the invention will become apparent in the following description of an embodiment with reference to the attached drawings, but which is not limiting in any way.

[0070] In these drawings: Fig. 1 is a diagram representing the operation of the process according to the invention, Fig. 2 is a schematic perspective view of a sieve used in the process according to the invention, Fig. 3 is a schematic top view of the sieve grid Fig. 2 , Fig. 4 is a larger-scale schematic view of a detail of Fig. 3 , Fig. 5 is a schematic perspective view of a sieve used in the process according to the invention, equipped with a roller brushing device, Fig. 6 is a side elevation view of the sieve of Fig. 5 , Fig. 7 is a view similar to Fig. 6 with a retractable support deployed, Fig. 8 And Fig. 9are views similar to Fig. 7 the retractable support moves to perform the cleaning, Fig. 10 is a view similar to Fig. 6 at the end of the cleaning process, Fig. 11 and Fig. 12 are views similar to Fig. 5 illustrating the position of the cart above one grid and another adjacent one, and Fig. 13 is a view similar to Figs. 11 and 12 with the trolley in the waiting position,

[0071] Fig. 1This allows us to place the invention in its context. We can see in the upper left the inlet line where the waste to be treated is introduced. After a first screen called primary, the fine fraction with a particle size of less than 450 mm passes through a rotating pre-fermentation tube then through a trommel where the finest fraction, with a particle size of less than 80 mm, is recovered and passes through a second trommel where the finest fraction, with a particle size of less than 20 mm, is recovered to be passed through a screen, i.e. the sieve according to the invention, which makes it possible to separate a first very fine fraction, with a particle size of less than 5 mm from a second fraction with a particle size between 5 and 20 mm.

[0072] Subsequently the first fraction passes through a mechanically agitated horizontal digester with at least partial recirculation via a mixing hopper.

[0073] It is during this digestion phase that biogas is extracted. The digestate is then composted for agricultural use.

[0074] The second fraction first passes through a ballistic separator to remove heavy waste before entering a digester in a similar manner to the first fraction. The digestate undergoes a maturation phase through draining or dehydration to stabilize it, transform it into fuel, or make it suitable for agricultural use.

[0075] Fig. 2 , we can see the screening device used in the process according to the invention.

[0076] The screening device comprises a frame 1 supporting an inclined grid 2. The grid 2 is situated in a plane inclined at an angle α to the horizontal.

[0077] Advantageously, grid 2 is mounted on a static grid support with an adjustable tilt from 30 to 60 degrees. In this embodiment, the tilt is 42° relative to the horizontal.

[0078] This steep incline allows the product being treated to flow down the slope without being forced through a mesh. Clogging is therefore much less frequent.

[0079] Grid 2 has an elongated shape, with a lower end (E2) and an upper end (E1) attached to tension systems 3 which allow a permanent voltage to be applied to grid 2 to keep it substantially flat.

[0080] Electromagnetic hammers 4, which transmit vibrations to the grid, are mounted on the sides of the grid, attached to the frame 1. These electromagnetic hammers can, for example, consist of electromagnets driving rotating cylinders fitted with protruding lugs or pins, arranged just below the grid, and extending transversely to the frame 1, at the level of the crossbars 6. The impact of the pins on the bar(s) 6 allows vibrations to be transmitted to the grid.

[0081] Grid 2 ( Fig. 4 ) is presented in the form of a series of longitudinal wires 5 exhibiting a substantially sinusoidal profile arranged in a rectangular shape.

[0082] The wires 5 are all on the same plane, with the distance between a wire 5 and its neighboring wires varying between a maximum and a minimum. However, even when the distance between a wire and its adjacent wire is minimal, there is no weld between the two wires. This particular arrangement was chosen after numerous tests. It minimizes clogging and facilitates cleaning of the grid. The maximum distance between the wires determines the mesh size L.

[0083] Crossbars 6 for stiffening are provided at regular intervals to maintain a constant spacing between the wires 5.

[0084] The four electromagnetic hammers are positioned opposite the stiffening bars. The frequencies used are generally between 10 and 60 Hz. When using multiple screening stages, it is possible to use different frequencies for each stage.

[0085] To ensure the process functions correctly, a cleaning step is planned.

[0086] Fig. 6 We can see a metal frame 7 placed above the grid 2. A trolley 8 is suspended under the frame 7 by means of rails so as to be able to slide transversely relative to the grid 2. The trolley 8 is made up of metal profiles assembled together to delimit in particular an upper surface 8a, on which rollers are fixed cooperating with the rails provided on the frame 7, and an inclined lower surface 8b, parallel to the surface of the grid 2, under which is mounted a retractable support 9 supporting cylindrical cleaning brushes 10. Means not shown are provided for driving the cylindrical brushes in rotation around their axis.

[0087] The retractable support 9 has two parallel faces 9a and 9b connected by connecting rods 9c. The first face 9a is mounted to slide under the carriage 8 while the second face 9b supports the cylindrical cleaning brushes 10.

[0088] Two grids (1.75 meters by 3.60 meters) are planned, placed side by side and fed by a V-shaped chute (not shown). This chute allows both grids to be fed simultaneously or just one of them.

[0089] In this way it becomes possible to temporarily reduce the flow of waste arriving at the screening station while directing the entire flow onto one of the two screens to allow the other screen to be cleaned in a continuous flow but without the presence of waste.

[0090] The trolley 8 can therefore be located above either of the grids or offset to the side, in a waiting position.

[0091] In operation, the trolley 8 is positioned in the waiting position as shown on Fig. 13 .

[0092] When a cleaning operation is deemed necessary, the trolley 8 is moved over one of the grids 2 which will be cleaned ( Figs. 11 and 12 ). The retractable support 9 is then in the folded position as illustrated Fig. 6 .

[0093] Once the trolley 8 has reached the position above the grid 2 to be cleaned, the retractable support 9 is unfolded ( Fig. 7 ) to bring the cylindrical brushes 10 into contact with the grid 2.

[0094] The retractable support 9 then moves downwards relative to the trolley 8, parallel to the grid 2, to carry out the cleaning ( Fig. 8 And 9 ).

[0095] Once the cleaning of grid 2 has been completed, the retractable support 9 is folded away ( Fig. 10 ) before the return of the carriage 8 to the waiting position ( Fig. 13 ).

[0096] Alternatively, a single screen is fitted to each screening machine, which has its own feed hopper and its own cleaning system comprising a carriage, one or more cylindrical brushes, and a system for moving the carriage over the screen. During cleaning cycles, the feed of material to the screen from the hopper is stopped, the carriage moves across the screen, and the cylindrical brush(s) in contact with the screen clean it. During screening, the carriage and the brushes are located at the bottom of the screen, in a raised position above the end (E2). Screening tests:

[0097] In a process for treating unsorted household waste as shown figure 1 , a screening machine as described above and shown in the figures 5 to 8, with integrated brushing system, was used, with different grids (2), to screen the fraction of material with a size between 0 and 20 millimeters, with a moisture content of about 50%, from the pre-fermentation rotary tube and the two trommels located downstream of this tube.

[0098] The grids that were used are as shown figure 2 These are flat grids with longitudinal wires of sinusoidal profile, not contiguous. The effective screening area was 3.45 m2 in all tests; the duration of the tests was 12 hours, including a 1.2 minute cleaning (feed stoppage) every 10 minutes.

[0099] In the various tests, the mesh size L and the diameter d of the wires were varied, and the quality and quantity of the fraction of material passing through the screen, intended for methanization and composting, were analyzed. (see Table 1).

[0100] The mass capture rate of the 0-5 mm fraction (of size less than millimeters), in the material passing the screen, is obtained by sieving this fraction in a sample of mass m of the feed material and weighing the mass obtained m' and carrying out the same operation for a mass m of material passing, to obtain a mass m" ; (m" / m')*100 is the capture rate (%).

[0101] Tests 1 and 2 show a low material throughput, indicating a screen clogging problem due to excessive wire rigidity and a small screen area. This is confirmed by the low capture rate of the 0-5 mm fraction.

[0102] The results are significantly improved in trials 7 and 8, where the wire diameter is reduced while maintaining a roughly the same mesh size. The output flow rate and the capture rate of the 0-5 mm fraction in the material passing through the screen are increased by approximately 50%. In terms of quality, the plastic content of the passing material remains zero, which is ideal. The glass content increases, but remains within acceptable limits for use in anaerobic digestion and composting.

[0103] In tests 3 and 4, increasing the mesh size led to very satisfactory flow rates and capture rates for the 0-5 mm fraction, but at the expense of quality in terms of glass content. The optimum compromise between quality and quantity was achieved in tests 5 and 6. Table 1 Grid: Mesh L, wire diameter Feed rate in 0-20 mm % Material throughput / feed rate % mass plastic in material passing % mass of glass in material passing Capture rate of the 0-5 mm fraction 1 L: 6 mm 3t / h 31% 0,1% 0,75% 43% d: 2.5 mm 2 L: 6 mm 4.8 t / h 23% 0,00% 0,70 % 37% d: 2.5 mm 3 L: 9 mm ? 57 % 0,15 % 2,10 % 89% d: 1.6mm 4.8 t / h 4 L: 9 mm 4.8 t / h 53 % 0,13% 1.98% 87% d: 1.6 mm 5 L: 8 mm 3.0t / h 57% 0,06% 1,20 % 94% d: 1.6 mm 6 L: 8 mm 4.8 t / h 48% 0,06% 1,50 % 82% d: 1.6 mm 7 L: 7 mm 3.1 t / h 47 % 0,05% 1,65% 69% d: 1.6 mm 8 L: 7 mm 4.3 t / h 41 % 66% d: 1.6 mm 0,03% 1,49%

Claims

1. A vibrating screening machine comprising: - a flat screening grid (2) comprising a series of metal wires (5) extending in substantially the same longitudinal direction, all the metal wires (5) being situated in the plane of the grid, the distance between a metal wire (5) and its adjoining wires varying between a maximum and a minimum, the minimum distance being non-zero, the grid (2) comprising at least one transverse bar (6), disposed perpendicularly to the direction of the longitudinal wires (5), said grid (2) being situated in a plane inclined at a non-zero angle α relative to the horizontal, and including a high end (E1) and a low end (E2), the mesh L of the grid (2) being included between 1 and 4 or between 5 and 12 millimeters; - a device for feeding material to be screened positioned at the high end (E1) of the grid, the direction of the longitudinal wires (5) of said grid being close to the direction of flow of the materials to be screened over the grid, - a vibration generator adapted to transmit vibrations to the grid (2) via the at least one transverse bar (6), - a brushing means (9, 10) adapted to execute a to-and-fro movement over the grid (2), the brushing means comprising at least one cylindrical brush (10) with its axis substantially parallel to the at least one transverse bar (6); characterized in that the diameter of the metal wires (5) of the grid (2) is between 0.5 and 2 millimeters, preferably between 1 and 1.7 millimeters inclusive and the at least one cylindrical brush (10) comprises bristles with a diameter between 0.4 and 1.0 millimeter.

2. The vibrating screening machine as claimed in claim 1, characterized in that the angle α is between 30° and 60° inclusive, preferably between 40 and 45° inclusive.

3. The vibrating screening machine as claimed in either one of claims 1 or 2, characterized in that the vibration generator comprises at least one electromagnetic hammer (4) positioned to strike at least one transverse bar (6).

4. The vibrating screening machine as claimed in claim 1 wherein the diameter of the at least one cylindrical brush (10) is between 500 and 700 millimeters inclusive and / or the cylindrical brush (10) is mounted on a mobile chassis (8, 9).

5. The vibrating screening machine as claimed in any one of claims 1 to 4, wherein the metal wires (5) have a substantially sinusoidal profile in the plane of the grid.

6. The vibrating screening machine as claimed in any one of claims 1 to 5, characterized in that, the mesh L of the grid (2) is included between 6 and 10 millimeters inclusive, preferably between 7 and 9 millimeters inclusive.

7. The vibrating screening machine as claimed in any one of claims 1 to 6, characterized in that the mesh L of the grid (2) is between 7 and 9 millimeters and in that the diameter of the wires of the grid (2) is between 1 and 1.7 millimeters.

8. The vibrating screening machine as claimed in any one of claims 1 to 5, characterized in that the mesh L of the grid (2) is between 1.5 and 3.5 millimeters, preferably between 2 and 3 millimeters.

9. A waste processing method comprising at least one step of vibrating screening of materials from / derived from waste on a machine as claimed in any one of claims 1 to 8, said step comprising the vibration of the grid (2) by a vibration generator positioned to transmit said vibrations to the grid (2) via the at least one transverse bar (6), some or all of the materials from the at least one vibrating screening step being possibly subjected to a treatment enabling their energy and / or material valorization.

10. The method as claimed in claim 9 wherein the waste contains organic materials mixed with undesirable materials, in particular metals, mineral materials, plastic materials, glass, and comprising: - at least one vibrating screening step carried out on a machine as claimed in any one of claims 1 to 9, said machine comprising a grid (2) the mesh L of which is between 6 and 10 millimeters inclusive, preferably between 7 and 9 millimeters inclusive, and - optionally, one or more grinding and / or screening steps enabling reduction of the particle size range of the waste intended to feed the vibrating screening step to a dimension less than 30 millimeters, preferably less than 20 millimeters.

11. The method as claimed in any one of claims 9 to 10, wherein the waste having passed through the at least one vibrating screening step is subjected to a methane production treatment in a digester.

12. The method as claimed in any one of claims 9 to 11 wherein the at least one vibrating screening step is preceded by a pre-fermentation treatment in a rotary tube with feeding at one end and extraction at the other end.

13. An installation for the execution of a method as claimed in any one of claims 9 to 12 comprising: - at least one vibrating screening machine as claimed in any one of claims 1 to 8, said machine comprising a grid (2) the mesh L of which is between 6 and 10 millimeters inclusive, preferably between 7 and 9 millimeters inclusive, - one or more grinding and / or screening devices enabling reduction of the particle size range of the waste intended to feed the vibrating screening machine to a dimension less than 30 millimeters, preferably less than 20 millimeters and possibly - at least one pre-fermentation rotary tube.

14. The method as claimed in claim 9, wherein the waste is dry waste with a high lower calorific value, and comprising: - one or more fine grinding steps enabling reduction of the particle size range of the waste to a dimension less than 30 millimeters, preferably less than 20 millimeters, followed by - at least one vibrating screening step carried out on a machine as claimed in any one of claims 1 to 8, said machine comprising a grid (2) the mesh L of which is between 1 and 4 millimeters, preferably between 1.5 and 3.5 millimeters, preferably between 2 and 3 millimeters; and possibly - upstream of the fine grinding step, one or more coarse grinding steps enabling reduction of the particle size range of the waste to a dimension less than 300 millimeters, preferably less than 200 millimeters.

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