Installation intended to separate, in an electric field, the components of a mixture of fibres and granules using a tribocharger provided with a grating for the selective confinement of said components

Abstract

The invention relates to an installation intended to separate the components of a mixture containing fibres (2) and granules (3), the installation comprising a tribocharger (4) for conferring an electrostatic charge upon the components (2, 3), at least one pair of electrodes (5, 6) for generating a separating electric field that conveys the charged components, according to their polarity, to collectors (10, 11), the installation being characterized in that the tribocharger (4) has a confinement grating (14) designed to keep the components in the tribocharger (4) until the components (2, 3) have attained sufficient charge, and then allow the components, once charged, to pass into the gap (7) from where the components (2, 3) reach their collector (10, 11) under the action of the separating electric field.

Description

[0001] The present invention relates to the general field of separation installations and processes intended to separate the different components of a mixture containing at least a first family of components and a second family of components.

[0002] The present invention finds particular application in the treatment of industrial waste which is in the form of a mixture containing at least two families of components, and in particular in the treatment of a mixture containing on the one hand fibers and on the other hand granules, with a view to recycling the materials constituting these components.

[0003] The invention finds particular application in the treatment of mixtures which are obtained from the grinding of pneumatic tires and which contain textile fibers, in particular polyethylene terephthalate, and granules of rubber-based material.

[0004] The present invention is particularly applicable to the processing of mixtures whose components are millimeter and sub-millimeter in size, that is to say in particular to the processing of mixtures which contain fibers whose diameter is between 10 µm and 1 mm for a length between 1 mm and 10 mm, and granules whose equivalent diameter is between 125 µm and 5 mm.

[0005] Many processes are known for separating the components of a mixture.

[0006] A process is known in particular from document FR-2 943 561 in which a mixture of different granules, belonging to two different material families, is poured onto a fluidized bed located in the lower part of an air gap delimited by two electrodes of opposite polarities. These electrodes are in the form of substantially vertical conveyor belts and generate an electric field in the air gap. When the fluidized bed agitates and suspends the granules composing the mixture in the air gap, it imparts to these granules, by triboelectric effect, an electrostatic charge whose sign depends on the family to which each granule belongs.Once a granule is electrically charged, said granule is attracted and captured by the electrode whose polarity is opposite to that of said granule, and thus adheres to the corresponding conveyor belt, which conveyor belt then transports said granule out of the air gap, to an appropriate collector.

[0007] While such an installation can be largely satisfactory in practice, it may nevertheless present some limitations and disadvantages.

[0008] Indeed, the inventors observed that while such a known installation could be very effective for processing relatively homogeneous granule mixtures, its efficiency dropped significantly when the mixture was composed of components heterogeneous in shape, and particularly when the mixture contained both granules and fibers. In the fluidized bed, the lighter fibers, which exhibit relatively high aerodynamic drag, tend to float above the granules, so the number of impacts between the fibers and the granules may not be sufficient to impart to the fibers a level of electrostatic charge sufficient for effective separation by the electric field.

[0009] Furthermore, the conveyor belts that form the electrodes can be relatively expensive to manufacture. Such a conveyor belt arrangement is also relatively vulnerable to fouling, since charged components, or even dust, can sometimes get trapped between a conveyor belt and the rollers that drive it, and where applicable, apply the necessary bias voltage to the belt. Such an incident can cause damage to the conveyor belt through deformation, which is potentially detrimental to the control of the electric field. Moreover, such damage is likely to increase the wear rate of the affected conveyor belt and thus reduce its lifespan.

[0010] Document US6927354B1 discloses a triboelectric charger featuring an inclined drum from which particles escape by gravity and not by the influence of an electrostatic field.

[0011] The objects assigned to the invention therefore aim to remedy the aforementioned drawbacks and to propose a new separation installation which has increased efficiency and reliability, in particular for the processing of mixtures composed of fibers and granules, while having a robust, simple and compact structure.

[0012] The objects assigned to the invention are achieved by means of a separation installation intended to receive a mixture containing at least a first family of components, preferably fibers, and a second family of components, preferably granules, said installation comprising a tribo-electric loading device, called a "tribocharger", which is arranged to receive the mixture and impart to the components of said mixture, by tribo-electric action, electrostatic charges which are of opposite polarities depending on whether the components belong to the first family or the second family, said installation further comprising at least a first electrode and a second electrode which are separated from each other by an air gap and connected to a generator which makes it possible to apply a potential difference between the first electrode and the second electrode in order to generate in the air gap an electric field, called a "separating electric field",which is intended to direct the charged components, according to their polarity, either towards a first collector intended to collect components of the first family, or respectively towards a second collector distinct from the first collector and intended to collect components of the second family, said installation being characterized in that the tribocharger receives the mixture inside an enclosure which is delimited by a containment wall which separates said enclosure from the first and second electrodes and from the first and second collectors, said containment wall being arranged in such a way that the mixture which is contained in the enclosure is subjected to the tribo-electric charging action and, simultaneously, exposed to the separating electric field, and said containment wall being provided with a grid which is arranged so as to retain components of the mixture inside the enclosure until said components have reached,Under the action of the tribocharger, an electrostatic charge sufficient for the said components to escape from the enclosure, passing through the containment wall via the grid, under the action of the separating electric field, and thus reach the collector corresponding to them, according to their polarity.

[0013] Advantageously, interposing a containment wall according to the invention between the enclosure and the collectors makes it possible to create a buffer zone, formed by the enclosure, in which the mixture is maintained for just the necessary and sufficient time to give the components, prior to the release of said components into the air gap, a level of electrostatic charge of said components which is sufficient to ensure that the components can be transported to the collectors and captured by said collectors, under the effect of the separating electric field.

[0014] The grid, like a sieve, fulfills a selection function by retaining uncharged or insufficiently charged components inside the enclosure, thus preventing these components from being prematurely released into the air gap, and in particular from falling into the air gap under the simple effect of gravity, while this same grid will be able to let these same components pass through once they are charged.

[0015] As long as the grid retains the components inside the enclosure, the tribocharger can reinforce the electrostatic charge of said components by continuing the tribo-electric action on them for the necessary duration, while the permanent immersion of the enclosure in the separating electric field allows said separating electric field to exert immediately and permanently an attractive force on the components, as soon as said components acquire an electrostatic charge.

[0016] Thus, more specifically, the permanent immersion of the enclosure, and therefore of the components being loaded contained within said enclosure, in the separating electric field advantageously allows said separating electric field to automatically extract the components, by facilitating or even forcing the passage of said components through the grid, as soon as the components have reached a sufficiently high electrostatic charge with regard to their size and shape.

[0017] In this respect, the invention is particularly well suited to the treatment of heterogeneous mixtures containing fibers and granules, and in particular mixtures containing highly variable proportions of fibers relative to granules.

[0018] The inventors have indeed observed that many fibers, due to their length, typically a length greater than the mesh of the sieve formed by the grid, can only leave the enclosure when they are sufficiently charged so that, pressed against the grid under the action of the separating electric field, the said fibers deform, in particular bend, and thus manage to pass through the grid.

[0019] Similarly, the inventors observed that uncharged granules generally clump together by adhering to fibers that impede them, preventing them from passing through the grid, even when an individual granule is smaller than the mesh size of the grid. Conversely, when the granules acquire a sufficient electrostatic charge, the electric field is able to detach them from the fibers and allow them to pass through the grid.

[0020] Thus, advantageously, the invention presents increased efficiency, since it allows for an almost systematic effective separation of the components, then an effective recovery of said components by the collectors according to the family to which said components belong, and this almost without generating residues or losses in the form of components that would remain trapped in the enclosure or respectively that, released into the gap, would escape capture by the collectors and fall to the bottom of the installation.

[0021] Other objects, features and advantages of the invention will become apparent in more detail from the following description, as well as from the accompanying drawings, which are provided for illustrative purposes only and are not intended to be limiting, including: There figure 1 The illustration shows, in perspective, an example of an installation according to the invention, comprising two pairs of rotating cylindrical electrodes with horizontal axes, forming two capture stages, and whose tribocharger is formed by a cylindrical confinement drum whose tubular side wall forms the grid that ensures the selective retention of the mixture components according to their electrostatic charge level. figure 2 is a front cross-sectional view of the installation of the figure 1 , in a vertical plane, substantially perpendicular to the axis of rotation of the containment drum and to the axes of rotation of the cylindrical electrodes. The figure 3 illustrates, according to a partial cross-sectional perspective view, the detail of the arrangement of the collectors of the first stage of electrodes of the installation of figures 1 And 2 , including scrapers for detaching components captured by the cylindrical electrodes. figure 4 illustrates, according to a schematic graph, the intensity of the separating electric field as a function of altitude, directly above the axis of rotation of the tribocharger of the installation. figures 1 à 3 , in the sagittal plane of the installation, and reveals two intensity peaks that correspond to the narrowing of the air gap between each of the two pairs of electrodes. The figure 5 illustrates, according to the same cutting plane as the figure 2 , a variant of the installation which includes a non-return baffle between the first pair of electrodes and the second pair of electrodes, in order to prevent the upward movement of components that are resuspended in the air gap by a fluidized bed located in the lower part of the installation. figure 6 illustrated, according to a front cross-sectional view in the same vertical cutting plane as that of the figure 2 , a variant of the installation layout of the figure 1 This is called a "staggered arrangement," in which the containment drum is positioned at an intermediate height between the two pairs of electrodes. figure 7 illustrates, according to the same schematic diagram as that of the figure 4 , the intensity of the electric field separator as a function of altitude, directly above the rotation axis of the tribocharger of the installation figure 6 , in the sagittal plane of said installation.

[0022] The present invention relates to a separation installation 100 intended to receive a mixture 1 containing at least a first family of components 2, preferably fibers 2, and a second family of components 3, preferably granules 3.

[0023] Preferably, the components of the first family will be fibers 2, which will have a thin and elongated shape, preferably substantially cylindrical. For the sake of simplicity, the components of the first family may therefore be referred to as fibers 2 in what follows.

[0024] At least some, preferably the majority of said fibers 2 present in mixture 1 (i.e., more than 50% of the total number of fibers present), and more preferably all (100% of the total number of fibers present) of said fibers 2 present in mixture 1 shall have a length between 1 mm and 10 mm, while the largest of their transverse dimensions, i.e., the largest of the dimensions considered perpendicular to their length, i.e., typically the diameter in the case of a cylindrical fiber, shall be between 10 µm and 1 mm. The installation 100 shall preferably be designed to be able to separate and recover (at least) fibers of such dimensions.

[0025] More preferably, the fibers 2 will have a dimension, called length, which is significantly greater than the other two dimensions, called transverse dimensions, and more particularly will have a length at least 5 times, preferably at least 10 times, at least 20 times, or even at least 50 times or even 100 times greater than the largest of these two transverse dimensions, that is to say, typically, in the case of a cylindrical fiber 2, a length at least 5 times, preferably at least 10 times, at least 20 times, or even at least 50 times or even 100 times greater than the diameter of the fiber 2 concerned.

[0026] Fibres 2 may be made from a natural or synthetic textile material, and more preferably from a polymer or a combination of polymers from (non-exhaustive list): polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS).

[0027] Preferably, the components of the second family will be granules 3. For the sake of simplicity of description, the components of the second family can therefore be considered as granules 3 in what follows.

[0028] At least part of the granules 3 present in mixture 1, preferably the majority of the granules 3 present in mixture 1 (more than 50% of the total number of granules present), and more preferably all (100% of the total number of granules present) of said granules 3 present in mixture 1 shall preferably have an equivalent diameter between 125 µm and 5 mm, and a shape factor between 1 and 2.

[0029] By "equivalent diameter" we mean the diameter that a fictitious sphere would have if it occupied the same volume as the volume occupied by the granule 3 under consideration.

[0030] The term "shape factor" refers to the ratio between, on the one hand, the maximum Feret diameter (i.e., the maximum observable distance for the given granule 3 between two parallel lines tangent to opposite sides of that granule 3), and, on the other hand, the minimum Feret diameter (i.e., the minimum observable distance for the given granule 3 between two parallel lines tangent to opposite sides of that granule 3). This shape factor provides a good indication of the slenderness of the granules. For reference, a shape factor of 1 corresponds to a sphere, and a shape factor equal to the square root of 2 corresponds to a cube.

[0031] The installation 100 will preferably be designed to be able to separate and recover (at least) granules 3 having the aforementioned dimensions, and more particularly to be able to sort, by separating them, on the one hand granules 3 of such dimensions and on the other hand fibers 2 having the dimensions mentioned above, which are initially mixed together in the mixture 1.

[0032] Preferably, the installation 100 will allow in particular the processing of mixtures 1 in which the proportion by weight of the fibers 2, in relation to the total weight of the mixture 1, represents between 5% and 75%, while the proportion by weight of the granules 3, in relation to the total weight of the mixture 1, represents between 25% and 95%.

[0033] The installation 100 includes a tribo-electric loading device 4, called a "tribo-loader" 4, which is arranged to receive the mixture 1 and to impart to the components 2, 3 of said mixture 1, by tribo-electric action, electrostatic charges which are of opposite polarities depending on whether the components 2, 3 belong to the first family (here the fibers 2) or to the second family (here the granules 3).

[0034] The tribocharger 4 ensures a mixing of components 2, 3, so that said components rub against each other and / or against a wall of the tribocharger 4, which creates transfers of electrons on their surface and thus gives said components 2, 3 electrostatic charges.

[0035] The installation 100 further includes at least a first electrode 5 and a second electrode 6 which are separated from each other by an air gap 7 and connected to a generator 8 which makes it possible to apply a potential difference between the first electrode 5 and the second electrode 6 in order to generate in the air gap 7 an electric field, called the "separating electric field".

[0036] This separating electric field is intended to direct the charged components 2, 3, according to their polarity, either towards a first collector 10 which is intended to collect components 2 of the first family, here fibers 2, or respectively towards a second collector 11 which is distinct from the first collector 10 and which is intended to collect components 3 of the second family, here granules 3.

[0037] The first electrode 5 is arranged to attract towards it, by the effect of Coulomb forces, the charged components of a family, here by convention the charged components of the first family, that is to say the charged fibers 2.

[0038] Said first electrode 5 could be distinct from the first collector 10 and placed in retreat from the first collector 10, relative to the area where the charged fibers 2 are released into the air gap 7, so that the fibers 2 which move towards the first electrode 5 under the effect of the separating electric field are intercepted and captured by the first collector 10 before reaching said first electrode 5.

[0039] However, preferably, the first electrode 5 is an integral part of the first collector 10, and is arranged to receive and capture the fibers 2 on its surface, as is the case on the embodiment variants of the figures 1 , 2 , 3 And 5 .

[0040] Similarly, the second electrode 6 is arranged to attract towards it, by the effect of Coulomb forces, the charged components of the other family, here by convention the charged components of the second family, that is to say the charged granules 3.

[0041] Said second electrode 6 could be separate from the second collector 11 and placed behind the second collector 11, relative to the area where the charged granules 3 are released into the air gap 7, so that the granules 3 which move towards the second electrode 6 under the effect of the separating electric field are intercepted and captured by the second collector 11 before reaching said second electrode 6.

[0042] However, preferably, the second electrode 6 is an integral part of the second collector 11, and is arranged to receive and capture the granules 2 on its surface, as is the case in the embodiment variants of figures 1 , 2 ,3 And 5 .

[0043] Preferably, as is clearly visible on the figure 2 , the tribocharger 4 is located directly above the air gap 7 and such that at least a part of said air gap 7 extends below the tribocharger 4, which advantageously allows the charged components 2, 3 from the tribocharger 4 to be discharged into the upper part of the air gap 7, and thus to be able to take advantage of a certain vertical amplitude of travel, or "free flight", during which said components 2, 3 are subjected, simultaneously to gravity, to the Coulomb forces due to the combination of their electrostatic charge and the separating electric field, so that said separating electric field is able to deflect said components 2, 3 and convey them to the collectors 10, 11 where said components are captured.

[0044] Accordingly, the first and second electrodes 5, 6 are preferably located on different sides of a vertical reference plane P0, which preferably forms a sagittal plane of the air gap 7 and more generally of the installation 100 and which preferably passes through the middle of the tribocharger 4, and said electrodes 5, 6 are preferably located at an altitude lower than that of the tribocharger 4. The same is preferably true for the corresponding collectors 10, 11, which laterally delimit the air gap 7, and which are located at an altitude lower than that of the tribocharger 4 and each on a different side of the reference plane P0.

[0045] According to the invention, the tribocharger 4 receives the mixture 1 inside a chamber 12 which is delimited by a containment wall 13 which separates said chamber 12 from the first and second electrodes 5, 6 and from the first and second collectors 10, 11.

[0046] Thus, the components 2, 3 introduced into the tribocharger 4 are initially captive within the enclosure 12 of the tribocharger 4, so that said components 2, 3 cannot directly reach the collectors 10, 11, or even the electrodes 5, 6, without first passing through the containment wall 13 which forms an obstacle between the inside of the enclosure 12 and said collectors 10, 11. In other words, the path which leads a component 2, 3 placed in the enclosure 12 to the collector 10, 11 dedicated to said component 2, 3 necessarily passes through, and through, the containment wall 13.

[0047] The containment wall 13 is arranged in such a way that the mixture 1 which is contained in the enclosure 12 is subjected to the tribo-electric loading action and, simultaneously, exposed to the separating electric field.

[0048] In other words, the enclosure 12, and therefore the components 2, 3 which said enclosure 12 holds captive, are immersed in the separating electric field, while the tribocharger 4 stirs said components 2, 3 inside the enclosure 12, in order to electrically charge said components 2, 3 by friction.

[0049] In addition, the containment wall 13 is provided with a grid 14 which is arranged so as to retain components 2, 3 of the mixture 1 inside the enclosure 12 until said components 2, 3 have reached, under the action of the tribocharger 4, an electrostatic charge which is sufficient for said components 2, 3 to escape from the enclosure 12, by passing through the containment wall 13 through the grid 14, under the action of the separating electric field, and can thus reach the collector 10, 11 which corresponds to them, according to their polarity.

[0050] The containment wall 13, and more particularly the grid 14, advantageously form a physical barrier which prevents the components 2, 3 of the mixture which are not yet charged, or which are insufficiently charged to be sure of reaching the collectors 10, 11, from escaping from the enclosure 12, which allows the tribocharger 4 to begin the action of charging said components 2, 3 and to continue the action of charging said components 2, 3 for as long as necessary, that is to say until said components 2, 3 are sufficiently charged to be released into the air gap 7, and carried by the separating electric field towards the collectors 10, 11.

[0051] The containment wall 13 thus defines, in a way, the boundary between two sub-chambers within the installation 100, namely, on the one hand, a first buffer sub-chamber, which is formed by the enclosure 12 closed by the containment wall 13 and its grid 14, and within which components 2 and 3 are introduced and can be held while said components 2 and 3 acquire a sufficient electrostatic charge, and on the other hand, a second sub-chamber, in which the collectors 10 and 11 are located, and which communicates with the enclosure 12 through the grid 14, here only through the grid 14, so that the collectors 10 and 11 are not accessible to components 2 and 3 as long as said components 2 and 3 are confined within the enclosure 12, but become accessible to said components as soon as said components 2 and 3 have passed through the grid 14 to to find themselves in the second sub-chamber, in "free flight" in the air gap 7,and therefore free to reach collectors 10, 11 under the action of the separating electric field.

[0052] The second sub-chamber can, in practice, correspond to the main enclosure of the installation 100, delimited by a casing which covers the frame of said installation.

[0053] Advantageously, the segregation operated by the grid 14 between sufficiently charged components 2, 3 and insufficiently charged components 2, 3 makes it possible to guarantee the quality and purity of the filtered products, i.e. the fibers 2 on the one hand and the granules 3 on the other hand which are collected separately by the collectors 10, 11, since only the components 2, 3 sufficiently charged to reach the collectors 10, 11, and to allow a differentiation of their family of belonging according to the sign of their charge, are actually extracted from the enclosure 12, and more particularly pulled from the enclosure 12 through the grid 14, then collected by the collectors 10, 11, while the insufficiently charged components 2, 3 cannot leave the triboloading zone.

[0054] The grid 14 may have any shape allowing the containment wall 13 to be perforated by defining a network of several through openings which will form as many passages for the components 2, 3, by connecting the interior of the enclosure 12 with the part of the air gap 7 located outside said enclosure 12, and whose dimensions will define a mesh adapted to the segregation function operated by the grid 14 against the components 2, 3.

[0055] This mesh, chosen to block uncharged components but to allow sufficiently charged components to pass through, will be defined according to the expected combination of the charge of components 2, 3 (and therefore the Coulomb force exerted on them by the separating electric field), the shape and dimensions of said components, and the mechanical properties of stiffness and elasticity of their constituent material.

[0056] The grid 14 will thus form a kind of sieve, which occupies all or part of the containment wall 13, and may be referred to as a "sieve" in what follows.

[0057] Preferably, and in particular having regard to the dimensions and preferential nature of the fibers 2 and granules 3 mentioned above, the grid 14 forms a sieve whose mesh M14 is between 1 mm and 10 mm, and more preferably between 2 mm and 5 mm.

[0058] It should be noted that, in absolute terms, it is not excluded that the mixture 1 may contain a certain quantity of components 2, 3 whose size would either be too large so as to prevent the components concerned, even carrying a high electrostatic charge and therefore subjected to a high Coulomb force, from passing through the mesh M14 of the grid 14, or on the contrary too small for the grid 14 to be able to effectively retain said components 2, 3, even uncharged, inside the enclosure 12, against gravity.

[0059] However, in the mixture 1 chosen to be treated by the installation 100, there is always at least one group of components 2, 3 which have sizes which, with regard to the electrostatic and mechanical properties of the material constituting said components 2, 3, are suitable so that these components, uncharged, and where appropriate agglomerated together, are retained by the grid 14 inside the enclosure 12, while these same components 2, 3, once intentionally charged by the action of the tribocharger 4, to a suitable charge level, will be able to pass through this same grid 14 under the action of the separating electric field.

[0060] In particular, at least some, preferably the majority or even all of the fibers 2 will preferably have a length greater than the M14 mesh, a diameter strictly less than the M14 mesh, and will be formed in a material sufficiently flexible to be able, once electrically charged, to bend under the action of the Coulomb force exerted by the separating electric field, typically bend in a U-shape, and thus pass through the M14 mesh of the grid 14.

[0061] Similarly, the granules 3 will preferably have an equivalent diameter substantially equal to the M14 mesh, or slightly less than the M14 mesh, for example between 80% and 100% of the M14 mesh, so as to be retained by the grid 14 when agglomerated with fibers 2, and to be able to pass through the meshes of the grid 14, either spontaneously or with a certain elastic restriction, when they are loaded and subjected to the attractive force of the separating electric field.

[0062] Of course, in the presence of a mixture 1 of given composition, the size of the M14 mesh of the grid 14 can be adapted to obtain the best possible yield of the installation 100, and in particular to optimize the selective retention capacity of the grid 14, that is to say optimize the compromise between the capacity of the grid 14 to retain the insufficiently charged components 2, 3, and its capacity to allow the sufficiently charged components 2, 3 to pass through.

[0063] Preferably, a mixture 1 will be prepared in which the components of the same family have relatively homogeneous properties from one component of the family to another, in that at least 50% by number of components 2 of the first family, and / or at least 50% by number of components 3 of the second family, or even at least 80% by number of components 2 of the first family and / or at least 80% by number of components 3 of the second family, will have properties, and in particular sizes, enabling them to meet the selectivity criterion, that is to say, to be sensitive to the segregation operated by the grid 14, which is blocking for said components 2, 3 (that is to say retains said components) when these are uncharged or insufficiently charged, and which becomes passing (that is to say lets said components pass) when these same components have acquired a sufficient charge.

[0064] The homogeneity of the components of the same family can for example be obtained by appropriately choosing the conditions for obtaining mixture 1, in particular when the mixture is obtained by grinding, and / or by possibly subjecting mixture 1 to a first sieving, possibly quite coarse, in order to calibrate said mixture 1 before introducing mixture 1 into the triboloader 4.

[0065] We can consider different types of triboloaders 4 to equip the installation 100.

[0066] However, preferably the triboloader 4 will be arranged so that it is the enclosure 12 which is set in motion, relative to the frame of the installation 100, preferably in rotational motion, so as to cause a mixing of the mixture 1 which causes friction of the components 2, 3 between them and with the containment wall 13 of the enclosure 12.

[0067] Preferably, as seen on the figures 1 , 2 ,3 And 5 The triboloader 4 comprises a cylindrical containment drum 15, preferably with a circular base, which is delimited by a tubular side wall 16 extending along and around a central axis X15 forming an angle of less than 30 degrees with the horizontal. This tubular side wall 16 forms the containment wall 13, and at least a portion of this tubular side wall 16 forms the grid 14.

[0068] Advantageously, the implementation of a 4-cylinder triboloader gives the installation a simple, compact, and robust structure.

[0069] Furthermore, by placing the mixture 1 in a tribocharger 4, and more particularly in a containment drum 15, which is horizontal and has a cylindrical shape, preferably a shape of revolution, one can advantageously use the rotation R15 of the drum 15 on itself, around its central axis X15, to carry out the mixing of the components 2, 3, and thus create or increase the electrostatic charge of said components 2, 3.

[0070] This rotation R15 is preferably ensured by a motor 17, such as an electric motor 17, controlled by a control unit 18.

[0071] The rotation R15 of the containment drum 15 about itself, around its central axis X15, is preferably continuous and monotonic, that is to say, carried out uninterrupted and always in the same direction. This advantageously results in efficient agitation of the mixture 1, without jerking or risk of compaction of the mixture 1, and moreover without jolts or vibrations of the triboloader 4, or excessive noise, which improves the service life, reliability, and ease of use of the installation 100.

[0072] The rotation speed R15 is moderate, so as on the one hand to allow a natural mixing of the mixture 1, by self-collapse and permanent turning of the mixture on itself, under the joint action of the rotation R15 (which allows the lateral wall 16 to carry and raise a part of the mixture along said lateral wall, in the direction of the rotation R15, seen in a section normal to the axis of rotation X15) and of gravity (which makes this part of the mixture raised by the rotation fall back onto the rest of the mixture), and on the other hand to avoid a centrifugal effect of the mixture 1 which would tend to compact said mixture 1 or even to prematurely eject, due to the centrifugal force, uncharged components 2, 3.

[0073] Thus, the rotational speed R15 will preferably be chosen, depending on the internal diameter of the containment drum 15, so that the centrifugal acceleration to which said rotation R15 subjects the mixture 1 remains less than 125 m / s², that is, less than 12.75 times the acceleration due to gravity. In practice, for a granule 3 with a mass of approximately 0.15 grams, such an acceleration will generate on said granule 3 a centrifugal force of approximately 0.018 Newtons.

[0074] As an indication, for an internal diameter of containment drum 15 preferably between 100 mm and 1000 mm, and more particularly between 120 mm and 500 mm, the rotation speed R15 will preferably be between 10 rpm and 150 rpm, more preferably between 30 rpm and 90 rpm.

[0075] The side wall 16 of the containment drum 15 may include a rigid openwork frame 20, which serves as a support for wire mesh panels 21, here curved panels which follow substantially or exactly the curvature of the side wall 16 of the containment drum 15, which wire mesh panels 21 fit the windows of the frame 20 so as to form as many portions of the grid 14.

[0076] The supply of enclosure 12 of the triboloader 4 can be carried out by any suitable feeding system, for example by means of a screw conveyor, of the Archimedes screw type, which takes the mixture 1 from a nearby silo to transfer it into enclosure 12, or by means of a hopper which pours the mixture 1 into said enclosure 12 of the triboloader 4.

[0077] Furthermore, it should be noted that, possibly, the radially internal face of the lateral wall 16 of the containment drum 15 may be provided with protrusions, such as blades, which contribute to breaking up and stirring the mixture 1 during the rotation R15, in order to accentuate the friction phenomena and thus improve the efficiency of the triboloading.

[0078] Although it is possible in theory to orient the central axis X15 of the containment drum 15 exactly horizontally, the central axis X15 will preferably form a non-zero angle with the horizontal.

[0079] This makes it possible to consider continuous operation of installation 100, i.e. a continuous supply of mixture 1 to tribocharger 4, and this with very low energy consumption.

[0080] Indeed, the central axis X15, and therefore the containment drum 15, is thus given an inclination which places the inlet of the containment drum, corresponding here to the base of the cylinder located at one of the two axial ends of said containment drum 15, considered along the central axis X15, at an altitude greater than the altitude of the outlet of the containment drum 15, which corresponds to the base of the cylinder forming the other axial end, opposite, of said containment drum 15.

[0081] Under the combined effect of the rotation R15 and gravity, this inclination of the containment drum 15, and more precisely of the lateral wall 16 of said containment drum 15, makes it possible to ensure a progressive and continuous transport of the mixture 1 from the inlet to the outlet of the containment drum, along the central axis X15.

[0082] It should be noted that, when the enclosure 12 is formed by a containment drum 15, care will be taken not to fill said containment drum 15 over its entire height, i.e. over the entire extent of its cross-section, in order to preserve in the upper part of the cylinder a sufficient vacuum to allow the mixture 1 to be effectively stirred during the rotation R15 of the containment drum 15. As an indication, the filling rate will be such that the mixture 1 occupies in the lower part of the cylinder a height less than or equal to 40% of the internal diameter of the containment drum 15, for example a height between 25% and 30% of said internal diameter.

[0083] Preferably, the first electrode 5 is formed by a cylindrical electrode 5, preferably with a circular base, mounted in rotation R5 around a first horizontal central axis X5 and whose surface forms a portion of the first collector 10, being able to collect the components 2 of the first family and to evacuate said components 2 out of the air gap 7 by its rotational movement R5.

[0084] Preferably, and in particular when the first electrode 5 is formed by a rotating cylindrical electrode as indicated above, the second electrode 6 is formed by a second cylindrical electrode 6, preferably with a circular base, which is mounted in rotation R6 around a second horizontal central axis X6, offset radially with respect to the first central axis X5, preferably parallel to the first central axis X5, and more preferably located at the same altitude as that of the first central axis X5.

[0085] The surface of the second cylindrical electrode 6 then advantageously forms a portion of the second collector 11 by being able to collect the components 3 of the second family and to evacuate said components 3 out of the air gap 7 by its rotational movement R6.

[0086] The central axes X5, X6 are substantially horizontal, that is to say they form an angle of less than 10 degrees with the horizontal, preferably less than 5 degrees, and more preferably will be exactly horizontal.

[0087] By "parallels," we indicate here that the central axes X5 and X6 extend along the same vector direction; that is, the first central axis X5 and the second central axis X6 are each normal to the same reference plane, here more preferably to the same vertical reference plane, as is the case with the projection plane of the figure 2 .

[0088] The first and second electrodes 5, 6 are preferably counter-rotating. More preferably, the directions of rotation R5, R6 are such that the tangential velocity of the surface of electrode 5, 6, considered at the narrowest point of the air gap 7 (here, the point on the surface of said electrode that is closest to the sagittal reference plane P0), rises vertically towards the tribocharger 4 located above the air gap 7, in the opposite direction to the natural fall of components 2, 3 under the effect of gravity. This notably ensures the safe transfer of components 2, 3 out of the air gap 7, preventing components 2, 3 captured by electrodes 5, 6 from accidentally detaching and falling towards the bottom of the installation 100.

[0089] Preferably, the first and second electrodes 5, 6 overlap axially at least partially, and more preferably overlap axially in total, in that said electrodes 5, 6 each occupy the same axial range considered, in the common direction of their central axes X5, X6.

[0090] When projected onto a horizontal plane, the tribocharger 4, and more specifically the containment drum 15, extends axially at least partially, preferably entirely, within the axial range common to the first electrode 5 and the second electrode 6. The central axis X15 of the containment drum 15 is preferably contained within a vertical plane, here the sagittal reference plane P0, which is parallel to the central axes X5, X6 of electrodes 5, 6 (and therefore, here, perpendicular to the vertical projection plane of the figure 2 ).

[0091] The first and second electrodes 5, 6 will preferably be driven in rotation R5, R6 by motors 22, 23, preferably electric motors 22, 23, controlled by the control unit 18.

[0092] Preferably, the first electrode 5 and the second electrode 6 form, at the minimum distance separating them, a first constriction 24 of the air gap 7, this first constriction 24 being located at a first altitude H24. The installation 100 includes a third electrode 30 and a fourth electrode 31, also subjected to a potential difference, which form, at the minimum distance separating them, a second constriction 32 of the air gap 7 located at a second altitude H32 lower than the first altitude H24. Thus, the separating electric field successively exhibits, vertically, a first peak of intensity 50 in the first constriction 24, at the first altitude H24, then an intensity which, between the first altitude H24 and the second altitude H32, first decreases and then increases again to form a trough of intensity 51 and then to reach a second peak of intensity 52 in the second tightening 32,at the second altitude H32, as illustrated on the , figure 4 or on the figure 7 .

[0093] The width of the first constriction 24 corresponds here to the difference between on the one hand the center distance which separates the central axes X5, X6 of the first and second electrodes 5, 6 and on the other hand the sum of the radius of the first electrode 5 and the radius of the second electrode 6.

[0094] Similarly, the width of the second constriction 32 corresponds here to the difference between on the one hand the center distance which separates the central axes X30, X31 of the third and fourth electrodes 30, 31 and on the other hand the sum of the radius of the third electrode 30 and the radius of the fourth electrode 31.

[0095] Advantageously, the installation 100 thus presents, according to a preferred feature which may constitute an invention in its own right, a structure comprising (at least) two capture stages 35, 36, namely a first capture stage 35, upper, corresponding to the first pair of electrodes formed by the first and second electrodes 5, 6 which define a part of the separating electric field whose intensity peaks at the first tightening 24, then a second capture stage 36, lower, corresponding to the second pair of electrodes formed by the third and fourth electrodes 30, 31 which define another part of the separating electric field whose intensity peaks at the second tightening 32.

[0096] According to a preferred arrangement variant that corresponds to figures 2, 3 , 4 et 5 , enclosure 12 of tribocharger 4 is located at an altitude, called "drop altitude" H12, which is higher than the first altitude H24 of the first narrowing 24.

[0097] Thus, a component 2, 3 that exits the enclosure 12 through the containment wall 13 and falls under the effect of gravity can, if necessary, successively pass through the first capture stage 35 and then the second capture stage 36, and therefore, in particular, the first intensity peak 50, by passing through the first constriction 24, then the second intensity peak 52, by passing through the second constriction 32. Therefore, if said component 2, 3 is too heavy and / or insufficiently charged, relative to its weight or relative to the initial distance separating said component from its corresponding collector 10, 11, to be captured by the upper first capture stage 35, then it is possible that said component 2, 3 may be captured, as a backup, by the lower second capture stage 36. In this way, a high recovery rate of components 2, 3 will be ensured.

[0098] According to another preferred arrangement variant, called "staggered arrangement", and which corresponds to figures 6 et 7 , the enclosure 12 of the triboloader 4 is located at an altitude, called "drop altitude" H12, which is intermediate, that is to say which is this time lower than the first altitude H24 of the first constriction 24 and higher than the second altitude H32 of the second constriction 32. In other words, the enclosure 12 of the triboloader 4, and more particularly the grid 14, is here, at least in part, or even in total, contained vertically between the first constriction 24 and the second constriction 32, so that the enclosure 12, and more particularly the grid 14, extends at least in part, and preferably in total, below the first constriction 24 and above the second constriction 32.

[0099] The inventors have indeed found that it was possible to obtain, using such a configuration in which the triboloader 4 is placed vertically in an intermediate position between the first and second constrictions 24, 32, an extraction of fibers 2 with a high degree of purity, higher than that observed in the previous configuration in which the triboloader 4 is placed above both the first constriction 24 and the second constriction 32. During the tests carried out by the inventors, this improvement in purity was observed at each of the two capture stages 35, 36.

[0100] More specifically, according to such a variant of staggered arrangement, and when using a containment drum 15 as described above, the central axis X15 of the containment drum 15 will be located at an intermediate altitude, strictly between the first altitude H24 of the first tightening 24 and the second altitude H32 of the second tightening 32.

[0101] More particularly, when using cylindrical electrodes 5, 6, 30, 31, whose respective altitudes are defined by their respective central axes X5, X6, X30, X31, then the central axis X15 of the containment drum 15 may be located at an altitude which is on the one hand lower than the altitude of the central axis X5 of the first electrode 5, and more preferably lower than both the altitude of the central axis X5 of the first electrode 5 and the altitude of the central axis X6 of the second electrode 6, and on the other hand higher than the altitude of the central axis X30 of the third electrode 30, and more preferably higher than both the altitude of the central axis X30 of the third electrode 30 and the altitude of the central axis X31 of the fourth electrode 31.

[0102] Such a staggered arrangement of the containment drum 15 with respect to a network of separate electrodes 5, 6, 30, 31 comprising a first, a second, a third and a fourth electrode 5, 6, 30, 31, so that the central axis X15 of the containment drum 15 is inscribed inside, and preferably is located at the center, of the prism whose central axes X5, X6, X30, X31 of said electrodes 5, 6, 30, 31 define the edges, can of course constitute an invention in its own right.

[0103] Preferably, regardless of the vertical positioning of the tribocharger 4, the third electrode 30 will be located on the same side of the sagittal reference plane P0 as the first electrode 5, here on the left of the figures 1 And 2 , and will exhibit the same polarity as the first electrode 5.

[0104] The third electrode 30 will preferably be associated with a third collector 33, separate from the first and second collectors 10 and 11, and is intended to collect the components 2 of the first family. More preferably, the third electrode 30 will be part of said third collector 33, arranged so as to be able to capture the components 2 on its surface.

[0105] Similarly, the fourth electrode 31 will preferably be located on the same side of the sagittal reference plane P0 as the second electrode 6, here on the right of the figures 1 And 2 , and will exhibit the same polarity as the second electrode 6.

[0106] The fourth electrode 31 will preferably be associated with a fourth collector 34, separate from the first, second, and third collectors 10, 11, 33, and intended to collect the components 3 of the second family. More preferably, the fourth electrode 31 will be part of said fourth collector 34, arranged so as to be able to capture the components 3 on its surface.

[0107] Preferably, the third and fourth electrodes 30, 31 are, just like the first and second electrodes 5, 6, each formed by a cylindrical electrode 30, 31, preferably with a circular base, mounted in rotation R30, R31 around its horizontal central axis X30, X31.

[0108] The characteristics described with reference to the first pair of electrodes 5, 6, particularly regarding the orientation of the axes and the directions of rotation R30, R31, can of course be applied mutatis mutandis to the second pair of electrodes 30, 31.

[0109] According to a particularly preferential feature, regardless of the arrangement of the electrodes 5, 6, 30, 31 and regardless of the intensity diagram of the separating electric field which is generated by said electrodes 5, 6, 30, 31, and in particular when the first, second, third and fourth electrodes 5, 6, 30, 31 are each formed by a rotating cylinder as indicated above, each of the first, second, third and fourth electrodes 5, 6, 30, 31 is associated with, or more preferably belongs to, a separate collector 10, 11, 33, 34, so that each of said first, second, third and fourth electrodes 5, 6, 30, 31 can evacuate out of the air gap 7, independently of the other electrodes 5, 6, 30, 31, the components 2, 3 captured on its surface.

[0110] Installation 100 thus presents a simple and inexpensive structure, which ensures separate evacuation, by capture stage 35, 36 and by polarity, of the different components 2, 3. This allows for easy and reliable sorting, with a high flow rate.

[0111] The collectors 10, 11, 33, 34 may be provided with scrapers 38, located outside the air gap 7, which rub against the corresponding electrode 5, 6, 30, 31 to detach the components 2, 3 captured by said electrode, which components 2, 3 may then be either temporarily stored in a container provided for this purpose, or evacuated by means of a suitable conveyor.

[0112] By "outside the air gap 7", we can here conventionally designate the region of space which is located on the opposite side to the center of the air gap 7, and therefore oriented towards the outside of the installation 100, with respect to a vertical reference plane which is parallel to the sagittal reference plane P0 and which contains the central axis X5, X6, X30, X31 of the electrode considered 5, 6, 30, 31.

[0113] According to a particularly simple implementation possibility, the potential difference applied between the third electrode 30 and the fourth electrode 31 can be identical to the potential difference applied between the first and second electrodes 5, 6. For this purpose, the first and third electrodes 5, 30 can both be connected to the same terminal of the generator 8, while the second and fourth electrodes 6, 31 are both connected to the same other terminal of the generator 8.

[0114] Alternatively, however, different potential differences could be applied to each pair of electrodes, if necessary by means of two separate generators or a single generator providing several independent outputs.

[0115] As a guideline, an installation with the following dimensional characteristics could be implemented: upper electrodes, i.e. the first and second electrodes 5, 6, each having a diameter, preferably equal, between 250 mm and 400 mm; lower electrodes, i.e. the third and fourth electrodes 30, 31, each having a diameter, preferably equal, between 250 mm and 500 mm; a containment drum 15 having an internal diameter between 200 mm and 300 mm; a smaller distance between the upper electrodes 5, 6, i.e. a first constriction 24, equal to the internal diameter of the containment drum 15 plus 200 mm; a smaller distance between the lower electrodes 30, 31, i.e. a second constriction 32, equal to 300 mm; and each electrode of the same pair (upper pair, respectively lower pair) being at the same altitude as the other electrode of the same pair.

[0116] Preferably, the installation 100 may include position adjustment devices 40, 41 allowing the position of one and / or the other of the central axes X15 of the containment drum and / or X5, X6, X30, X31 of one or the other of the electrodes 5, 6, 30, 31 to be changed.

[0117] In particular, as can be seen on the figure 1 , a system of vertical rails 40 can be provided allowing modification, preferably independently of each other, of the altitude of the containment drum 15, respectively one and / or the other of the altitudes of the electrodes 5, 6, 30, 31.

[0118] Similarly, horizontal rails 41 can be provided, preferably perpendicular to the central axes X15, X5, X6, X30, X31, to modify the horizontal position of the electrodes 5, 6, 30, 31, preferably independently of each other, so as to be able in particular to adjust and modify as needed the center distances of each pair of electrodes 5, 6, respectively 30, 31, and / or the distance of one and / or the other of the electrodes from the vertical plumb of the tribocharger (here therefore the distance from the reference plane P0).

[0119] Preferably, the surface, preferably cylindrical, of the electrodes 5, 6, 30, 31 is covered with a layer made of an electrically insulating material to prevent an exchange of charges of the electrode 5, 6, 30, 31 with the components 2, 3 which adhere to its surface.

[0120] By "electrically insulating material" we mean here a material which has a resistivity equal to or greater than 10< Ω.m at a temperature of 300 Kelvin.

[0121] This insulating layer could, for example, take the form of a coating, for example in PTFE or PET, preferably with a thickness between 10 µm and 100 µm, which will be deposited on the core of the electrode, itself made of metal, for example in copper alloy, aluminum alloy or stainless steel.

[0122] Preferably, the electrodes 5, 6, 30, 31 which define the separating electric field occupy, as a whole, an altitude range H7 called the "air gap altitude range" H7 which extends from the altitude of the lowest point of all said electrodes, here the bottom line of the third or fourth electrode 30, 31, to the highest point of all said electrodes, here the crest line of the first or second electrode 5, 6, and the tribocharger 4, called the "first tribocharger" 4, is located in a high part of the installation 100 so that at least a part, preferably at least half, and more preferably the whole, of the air gap altitude range H7 extends below the altitude H12 of the lowest point of the enclosure 12 receiving the mixture 1, that is, below the H12 drop altitude mentioned above.

[0123] Thus, the enclosure 12, and more particularly the grid 14, is located in the upper part of the air gap 7, so that the components 2, 3 which exit the enclosure 12, at the drop altitude H12, benefit from a significant drop height, which leaves space and time for the electrodes 5, 6, 30, 31 to deflect the trajectory of said components towards the collectors 10, 11, 33, 34.

[0124] In all cases, of course, the tribocharger 4, and more particularly the enclosure 12 and its grid 14, remain placed in the area of ​​influence of the separating electric field, so that the components 2, 3 are caught by said separating electric field and pulled out of the enclosure 12, through the grid 14, immediately charged.

[0125] According to a particularly preferred feature which may constitute an invention in its own right, especially regardless of the nature of the first triboloader 4, the installation 100 may then also include, in a lower part, directly below the first triboloader 4 and at an altitude H45 strictly lower than the altitude of said first triboloader 4, here therefore strictly lower than the release altitude H12, a fluidized bed 45, schematically represented by dotted lines on the figure 2 , which forms a second tribocharger 45 capable of electrically recharging and returning in suspension in the air gap 7 the components 2, 3 of the mixture 1 which would have fallen from the first tribocharger 4 and would have crossed vertically through the air gap 7 without being captured by the collectors 10, 11, 33, 34.

[0126] Advantageously, this further improves the efficiency of installation 100, by reducing the losses that would correspond to a residue formed by components that fell from the enclosure but were not captured and therefore not sorted after passing through installation 100.

[0127] According to a preferred feature which may constitute an invention in its own right, the installation 100 comprises, at an intermediate altitude located between the upper first capture stage 35, formed by the first electrode 5 and the second electrode 6 and the lower second capture stage 36, formed by the third electrode 30 and the fourth electrode 31, a non-return baffle 46 which is arranged to allow the passage to the second capture stage 36 of the components 2, 3 not captured by the first capture stage 35, while preventing the components 2, 3 resuspended in the second capture stage 36 by the fluidized bed 45 from rising beyond said non-return baffle 46, and in particular from rising back to the first capture stage 35.

[0128] The said anti-return baffle 46 preferably comprises firstly, as can be seen on the figure 5 , a hopper 47 with converging walls which is suitable for collecting the components 2, 3 falling from the first capture stage 35 and for directing said components 2, 3, through a lower opening 48, towards the second capture stage 36, then a diverging deflector 49, which is placed under the hopper 47 in line with the lower opening 48 so as to allow the components 2, 3 from the hopper 47 to fall into the second capture stage 36, while preventing the components 2, 3 resuspended in the second capture stage 36 by the fluidized bed 45 from rising through the lower opening 48 towards the first capture stage 35, and therefore from rising beyond said non-return baffle 46, and in particular from rising up to the first capture stage 35.

[0129] Advantageously, in the second capture stage 36, in the air gap delimited by the third and fourth electrodes 30, 31, the components 2, 3 which were not captured during their first fall and which are put back into suspension, by the fluidized bed 45, in the lower part of the air gap 7, are thus confined in the second capture stage 36, in the air gap delimited by the third and fourth electrodes 30, 31. This improves the efficiency of the installation, by preventing the fluidized bed 45 from dispersing the components 2, 3 out of the air gap 7.

[0130] The width covered horizontally by the deflector 49 preferably represents at least 50%, at least 75%, at least 85%, or even at least 95% of the horizontal distance separating the third electrode 30 from the fourth electrode 31. Thus, the deflector 49 forms a kind of cap which covers the majority, or even all, of the lower area of ​​the air gap 7 which is between the third and fourth electrodes 30, 31, and constitutes an obstacle which prevents the components 2, 3 present in this lower area of ​​the air gap 7 from leaving said lower area of ​​the air gap.

[0131] The deflector 49 is preferably arranged so as to fully overlap and cover, in projection in a horizontal plane, the lower opening 48 of the hopper 47, and even to extend beyond the lower opening 48, so that the components 2, 3 present in the lower area of ​​the air gap, under the deflector 49, cannot rise vertically through said lower opening 48.

[0132] Advantageously, the non-return baffle 46 also prevents the gas flow, here upward, emitted by the fluidized bed 45 from disturbing the operation of the first capture stage 35, in the upper part of the air gap 7.

[0133] The walls of the hopper 47, respectively the walls of the deflector 49, may be formed by inclined plates which extend lengthwise parallel to the axes X5, X6, X30, X31 of the electrodes 30, 31.

[0134] These walls, and more generally the anti-return baffle 46, may be animated by vibrations, to prevent components 2, 3 from adhering to said walls.

[0135] Preferably, the generator 8 and the electrodes 5, 6, and where applicable 30, 31, are arranged so that the intensity of the separating electric field, at the level of the inner face of the grid 14 which retains the components, here in particular in the immediate vicinity of the drop altitude H12 or even at the drop altitude H12, is equal to or greater than 100 kV / m, preferably between 100 kV / m and 600 kV / m, and more preferably between 200 kV / m and 400 kV / m.

[0136] Such intensity will advantageously be high enough to force the extraction of components 2, 3 charged through the grid 14.

[0137] Furthermore, choosing a moderate intensity, for example equal to or less than 400 kV / m, will advantageously allow the separating electric field to be created by means of generators 8 with a maximum voltage of less than 100 kV, and which are therefore relatively inexpensive and not very restrictive to implement, especially in view of the safety standards applicable to such generators 8 with regard to isolation distances.

[0138] It should be noted that the required intensity can in particular be obtained by creating a potential difference of 50 kV, here in direct voltage, for example between a first and a second electrode 5, 6 which are spaced at a center distance of 80 cm, which each have a diameter of 30 cm, and which are associated with a confinement drum 15 having, at the level of the grid 14, an internal diameter of 30 cm, whose central axis X15 is located horizontally in the middle of the center distance separating the central axis X5 of the first electrode 5 from the central axis X6 of the second electrode, and vertically at an altitude between 0 cm and 40 cm above the common altitude of the two central axes X5, X6 of the said first and second electrodes.

[0139] At the first narrowing 24, at the first altitude H24, the intensity of the separating electric field may be between 100 kV / m and 400 kV / m.

[0140] At the second narrowing 32, at the second altitude H32, the intensity of the separating electric field may be between 200 kV / m and 600 kV / m.

[0141] The electric field strength values ​​given above for the first altitude H24 and the second altitude H32 may correspond, in particular, to a situation in which, as illustrated on the figures 3 And 5 , the shortest distance separating the first electrode 5 from the second electrode 6 is greater than the shortest distance separating the third electrode 30 from the fourth electrode 31.

[0142] That being said, the distances separating electrodes 5, 6, respectively 30, 31 of the same pair can of course be adjusted, as well as the potential difference applied between these electrodes, depending on the desired intensity of the separating electric field.

[0143] Thus, in particular, and as illustrated here on the figure 6 , the first electrode 5 and the second electrode 6 may be closer to each other than are the third and fourth electrodes 30, 31 to each other, that is to say that the shortest distance separating the first electrode 5 from the second electrode 6 may be chosen smaller than the shortest distance separating the third electrode 30 from the fourth electrode 31, instead of being chosen larger.

[0144] If necessary, the intensity of the separating electric field may then be higher in the first constriction 24 than in the second constriction 32, as illustrated in the figure 7 . For example, the intensity of the separating electric field may this time be between 200 kV / m and 600 kV / m at the first altitude H24 of the upper constriction 24, while it will be between 100 kV / m and 400 kV / m at the second altitude H32 of the lower constriction 32.

[0145] Of course, the invention relates as such to a separation process allowing, from a mixture 1 which contains at least a first family of components 2, preferably fibers 2, and a second family of components 3, preferably granules 3, to separate the components 2 belonging to the first family from the components 3 belonging to the second family.

[0146] Such a process can preferably be implemented using an installation 100 as described above.

[0147] It should be noted that the process according to the invention is preferably and advantageously a dry separation process, which does not require the use of solvent or the treatment of components 2, 3 with any liquid solution.

[0148] The separation process according to the invention comprises a step (S1) of creating a separating electric field, during which a potential difference is applied between at least a first electrode 5 and a second electrode 6 defining an air gap 7 between them so as to generate in said air gap 7 an electric field called the "separating electric field", a step (S2) of electrostatic charging of the mixture 1, during which components 2, 3 of the mixture are imparted, by tribo-electric action, electrostatic charges which are of opposite polarities depending on whether the components 2, 3 belong to the first family or the second family, then a sorting step (S3) during which the separating electric field is used to direct the charged components 2 of the first family towards a first collector 10 which captures said components 2 of the first family,and to direct the charged components 3 of the second family towards a second collector 11 which is separate from the first collector 10 and which captures said components 3 of the second family.

[0149] According to the invention, the electrostatic charging step (S2) comprises a selective retention phase (S201), during which the mixture 1 is placed inside a chamber 12 which is separated from the first and second electrodes 5, 6 and the first and second collectors 10, 11 by a containment wall 13, and said mixture 1 present in the chamber is subjected to triboelectric action, in the presence of the separating electric field, and, depending on whether the level of electrostatic charge reached by certain components 2, 3 corresponds or not to a charge level deemed sufficient, said components 2, 3 are allowed to leave the chamber 12 so that said components 2, 3 can reach the collectors 10, 11 under the action of the separating electric field, or on the contrary, said components 2, 3 are temporarily prevented from leaving the chamber, by retaining them by means of the containment wall 13, and by continuing the tribo-electric action on said components 2, 3,until these same components 2, 3 have acquired an electrostatic charge of a charge level deemed sufficient to be released from enclosure 12, towards collectors 10, 11.

[0150] Thus, the sorting step (S3) is preceded by a selective retention step (S201) which allows the components 2, 3, initially uncharged or slightly charged, to be maintained here by means of the grid 14, in the buffer zone formed by the enclosure 12, until these same components have acquired a charge which is sufficient to trigger their extraction out of the enclosure 12, through the grid 14, and their release into the air gap 7, from where the said charged components 2, 3 then travel to the collectors 10, 11.The grid 14, and more particularly the dimensioning of the mesh M14 of the sieve formed by said grid 14, advantageously allows to ensure automatically, for each component 2, 3 considered individually, that the release of said component in the air gap 7 occurs only, and as soon as, the conditions, in particular the threshold of electrostatic charge adapted to the component considered, are met for the separating electric field to carry said component to the collector 10, 11 which corresponds to it.

[0151] Preferably, during the separation process according to the invention, a separating electric field is created which extends at least partly below the enclosure 12, and which has at least two intensity peaks 50, 52 vertically staged and separated by an intensity trough 51, so as to form a first upper capture stage 35, with which at least part of the components 2, 3 from the enclosure 12 are captured, then a second lower capture stage 36 with which at least part of the components 2, 3 from the enclosure 12 and not captured by the first upper capture stage 35 are captured.

[0152] Each stage 35, 36 preferably corresponds to a different pair of electrodes 5, 6, respectively 30, 31.

[0153] Advantageously, such a tiered structure considerably limits the fall of components 2, 3 into the bottom of the installation, and promotes efficient evacuation of each family of components, with a good flow rate, because said evacuation is distributed over two tiers 35, 36, and thus two tiers 35, 36 of capture are allocated to the capture and evacuation of the same family of components, and therefore several collectors working simultaneously.

[0154] Of course, one could, for example, either, in accordance with what was described above concerning the first arrangement variant of the installation 100, ensure that the at least two intensity peaks 50, 52, and therefore the two capture stages 35, 36, are both located below the enclosure 12, that is to say, at an altitude lower than the release altitude H12, or, in accordance with what was described concerning the second variant, known as the "staggered" arrangement, ensure that the first intensity peak 50, and therefore the first capture stage 35, is instead located above the enclosure 12, at the very least above the release altitude H12 corresponding to the lowest point of the enclosure 12 (and therefore of the grid 14) through which components 2, 3 of mixture 1 can escape, while the second intensity peak 52, and therefore the second capture stage 36, is located below enclosure 12, at an altitude lower than the drop altitude H12.

[0155] Preferably, the separation process is applied to a mixture 1 which comprises as a first component family fibers 2, preferably based on polyethylene terephthalate, and as a second component family granules 3, preferably based on rubber.

[0156] At least some of the fibers 2, preferably the majority of the fibers 2 (i.e. more than 50% of the number of fibers present), or even all of the fibers 2, have a length equal to or greater than a first predetermined reference value L2, while at least some of the granules 3, preferably the majority of the granules (i.e. more than 50% of the number of granules present), or even all of the granules 3, have an equivalent diameter which is equal to or less than a second predetermined reference value L3, strictly less than the first reference value L2.

[0157] Advantageously, to carry out the selective retention phase (S201), a grid 14 integrated into the containment wall 13 can then be used, forming a sieve whose mesh size M14 is between the first reference value L2 and the second reference value L3, i.e.: L3 < M14 < L2

[0158] According to a particularly preferred application possibility, the invention relates to a method for recycling a pneumatic tire comprising a grinding step, during which at least a portion of said pneumatic tire, for example the tread of said tire, is reduced into a mixture containing textile fibers 2 and granules 3 of rubber-based material and then a separation step during which said mixture is subjected to a separation process according to any one of the characteristics described above.

[0159] Of course, the invention is by no means limited to the examples of embodiment described above, and is defined by the attached claims.

Claims

1. Separation installation (100) intended to receive a mixture (1) containing at least one first family of components (2), preferably fibres (2), and one second family of components (3), preferably granules (3), said installation (100) comprising a triboelectric charging device (4), called "tribocharger" (4), which is arranged to receive the mixture (1) and, through the triboelectric effect, to confer electrostatic charges upon the components (2, 3) of said mixture, which electrostatic charges have opposite polarities depending on whether the components (2, 3) belong to the first family or to the second family, said installation (100) further comprising at least one first electrode (5) and one second electrode (6), which are separated from each other by a gap (7) and are connected to a generator (8) that allows a potential difference to be applied between the first electrode (5) and the second electrode (6) in order to generate an electric field, called "separating electric field", in the gap that is intended to direct the charged components (2, 3), according to their polarity, either towards a first collector (10) intended to collect components (2) of the first family, or, respectively, towards a second collector (11) distinct from the first collector (10) and intended to collect components (3) of the second family, said tribocharger (4) being configured to receive the mixture (1) inside an enclosure (12) that is delimited by a containment wall (13) that separates said enclosure (12) from the first and second electrodes (5, 6) and first and second collectors (10, 11), said containment wall (13) being arranged such that the mixture (1) that is contained in the enclosure (12) experiences the triboelectric charging effect and is simultaneously exposed to the separating electric field, and said containment wall (13) being provided with a grating (14) that is arranged so as to retain components (2, 3) of the mixture inside the enclosure (12) until said components (2, 3) have reached, under the effect of the tribocharger (4), an electrostatic charge that is sufficient for said components (2, 3) to escape from the enclosure (12), by crossing the containment wall (13) through the grating (14), under the effect of the separating electric field, and to thus reach the collector (10, 11) that corresponds to them, as a function of their polarity.

2. Installation according to Claim 1, characterized in that the tribocharger (4) comprises a cylindrical containment drum (15) that is delimited by a tubular side wall (16) that extends along and around a central axis (X15) forming an angle of less than 30 degrees with the horizontal, preferably a non-zero angle, which tubular side wall (16) forms the containment wall (13) and at least one portion of which forms the grating (14).

3. Installation according to Claim 1 or Claim 2, characterized in that the first electrode (5) is formed by a cylindrical electrode rotatably mounted (R5) about a first horizontal central axis (X5) and the surface of which forms a portion of the first collector (10) while being capable of collecting the components (2) of the first family and of discharging said components (2) out of the gap (7) by its rotational movement (R5), and in that the second electrode (6) is formed by a second cylindrical electrode (6) rotatably mounted (R6) about a second horizontal central axis (X6), radially offset relative to the first central axis (X5), preferably parallel to the first central axis (X5), and more preferably located at the same altitude as that of the first central axis (X5), with the surface of said second cylindrical electrode (6) forming a portion of the second collector (11) while being capable of collecting the components (3) of the second family and of discharging said components (3) out of the gap (7) by its rotational movement (R6).

4. Installation according to any of the preceding claims, characterized in that the first electrode (5) and the second electrode (6) together form, at the minimum distance between them, a first constriction (24) of the gap (7) located at a first altitude (H24), in that the installation (100) comprises a third electrode (30) and a fourth electrode (31), also experiencing a potential difference, and which together form, at the minimum distance between them, a second constriction (32) of the gap (7) that is located at a second altitude (H32) lower than the first altitude (H24), such that the separating electric field successively has, along the vertical, a first intensity peak (50) in the first constriction (24), at the first altitude (H24), then an intensity which, between the first altitude (H24) and the second altitude (H32), firstly decreases and then re-increases in order to form an intensity trough (51) and then to reach a second intensity peak (52) in the second constriction (32), at the second altitude (H32), and in that the enclosure (12) of the tribocharger (4) is located at an altitude, called "drop altitude" (H12), that is greater than the first altitude (H24) of the first constriction (24).

5. Installation according to any of Claims 1 to 3, characterized in that the first electrode (5) and the second electrode (6) together form, at the minimum distance between them, a first constriction (24) of the gap (7) located at a first altitude (H24), in that the installation (100) comprises a third electrode (30) and a fourth electrode (31), also experiencing a potential difference, and which together form, at the minimum distance between them, a second constriction (32) of the gap (7) that is located at a second altitude (H32) lower than the first altitude (H24), such that the separating electric field successively has, along the vertical, a first intensity peak (50) in the first constriction (24), at the first altitude (H24), then an intensity which, between the first altitude (H24) and the second altitude (H32), firstly decreases and then re-increases in order to form an intensity trough (51) and then to reach a second intensity peak (52) in the second constriction (32), at the second altitude (H32), and in that the enclosure (12) of the tribocharger (4) is located at an intermediate altitude, called "drop altitude" (H12), that is lower than the first altitude (H24) of the first constriction (24) and higher than the second altitude (H32) of the second constriction (32).

6. Installation according to Claim 3 and any of Claims 4 or 5, characterized in that the third and fourth electrodes (30, 31) are each also formed by a cylindrical electrode (30, 31) rotatably mounted (R30, R31) about its horizontal central axis (X30, X31), and in that each of the first, second, third and fourth electrodes (5, 6, 30, 31) belongs to a distinct collector (10, 11, 33, 34), such that each of said first, second, third and fourth electrodes (5, 6, 30, 31) can discharge the components (2, 3) captured on its surface out of the gap (7), independently of the other electrodes (5, 6, 30, 31).

7. Installation according to any of the preceding claims, characterized in that the surface, preferably cylindrical, of the electrodes (5, 6, 30, 31) is covered with a layer made of an electrically insulating material in order to prevent an exchange of charges from the electrode (5, 6, 30, 31) with the components (2, 3) that adhere to its surface.

8. Installation according to any of the preceding claims, characterized in that the electrodes (5, 6, 30, 31) that define the separating electric field as a whole occupy an altitude range (H7), called "altitude range of the gap" (H7), that extends from the altitude of the lowest point of all of said electrodes to the highest point of all of said electrodes, in that the tribocharger (4), called "first tribocharger" (4), is located in an upper part of the installation (100), such that at least part, preferably at least half, and more preferably all, of the altitude range (H7) of the gap extends below the altitude (H12) of the lowest point of the enclosure (12) receiving the mixture (1), and in that the installation (100) comprises, in a lower part, in line with the first tribocharger (4) and at an altitude (H45) that is strictly lower than the altitude of said first tribocharger (4), a fluidized bed (45) that forms a second tribocharger (45) capable of electrically recharging and of resuspending the components (2, 3) of the mixture (1) in the gap (7), which components would have fallen from the first tribocharger (4) and would have vertically passed through the gap (7) without being captured by the collectors (10, 11, 33, 34).

9. Installation according to Claim 8 and any of Claims 4 to 6, characterized in that it comprises, at an intermediate altitude located between a first upper capturing stage (35), formed by the first electrode (5) and the second electrode (6), and a lower second capturing stage (36), formed by the third electrode (30) and the fourth electrode (31), a non-return baffle (46) that is arranged to allow the components (2, 3) not captured by the first capturing stage (35) to pass towards the second capturing stage (36), while preventing the components (2, 3) resuspended in the second capturing stage (36) by the fluidized bed (45) from rising beyond said non-return baffle (46), with said non-return baffle (46) to this end preferably initially comprising a hopper (47) with converging walls that is able to collect the components (2, 3) falling from the first capturing stage (35) and to direct said components (2, 3), through a lower opening (48), towards the second capturing stage (36), then comprising a divergent deflector (49), which is placed under the hopper (47) in line with the lower opening (48) so as to allow the components (2, 3) originating from the hopper (47) to fall in the second capturing stage (36), while preventing the components (2, 3) resuspended in the second capturing stage (36) by the fluidized bed (45) from rising through the lower opening (48) towards the first capturing stage (35).

10. Installation according to any of the preceding claims, characterized in that the generator (8) and the electrodes (5, 6, 30, 31) are arranged such that the intensity of the separating electric field, on the inner face of the grating (14) that retains the components (2, 3), is equal to or greater than 100 kV / m, preferably ranging between 100 kV / m and 600 kV / m, and more preferably ranging between 200 kV / m and 400 kV / m.

11. Installation according to any of the preceding claims, characterized in that the grating (14) forms a screen, the mesh (M14) of which ranges between 1 mm and 10 mm, and more preferably between 2 mm and 5 mm.

12. Separation method allowing, from a mixture (1) that contains at least a first family of components (2), preferably fibres (2), and a second family of components (3), preferably granules (3), the components (2) belonging to the first family to be separated from the components (3) belonging to the second family, said method to this end comprising a step (S1) of creating a separating electric field, during which step a potential difference is applied between at least one first electrode (5) and one second electrode (6) together defining a gap (7) so as to generate an electric field, called "separating electric field", in said gap, a step (S2) of electrostatically charging the mixture (1), during which step electrostatic charges are conferred upon the components (2, 3) of the mixture by the triboelectric effect, which electrostatic charges have opposite polarities depending on whether the components belong to the first family or the second family, then a sorting step (S3), during which the separating electric field is used to direct the charged components (2) of the first family towards a first collector (10) that captures said components (2) of the first family, and to direct the charged components (3) of the second family towards a second collector (11) that is distinct from the first collector (10) and that captures said components (3) of the second family, said method being characterized in that the electrostatic charging step comprises a selective retention phase (S201), during which the mixture (1) is placed inside an enclosure (12) that is separated from the first and second electrodes (5, 6) and from the first and second collectors (10, 11) by a containment wall (13), and said mixture (1) present in the enclosure (12) is subjected to the triboelectric effect, in the presence of the separating electric field, and, depending on whether or not the level of electrostatic charge reached by some components (2, 3) corresponds to a charge level that is considered to be sufficient, said components (2, 3) are allowed to exit the enclosure (12) so that said components can reach the collectors (10, 11) under the effect of the separating electric field, or, on the contrary, said components (2, 3) are temporarily prevented from exiting the enclosure (12), by retaining them by means of the containment wall (13), and by continuing the triboelectric effect on said components (2, 3), until said components (2, 3) have acquired an electrostatic charge with a charge level that is considered to be sufficient to be able to be released from the enclosure (12) towards the collectors (10, 11).

13. Separation method according to Claim 12, characterized in that a separating electric field is created that at least partially extends below the enclosure (12), and that has at least two intensity peaks (50, 52) vertically stepped and separated by an intensity trough (51), so as to form a first upper capturing stage (35), with which at least some of the components (2, 3) originating from the enclosure (12) are captured, then a second lower capturing stage (36) with which at least some of the components (2, 3) originating from the enclosure (12) and not captured by the first upper capturing stage (35) are captured.

14. Separation method according to Claim 12 or Claim 13, characterized in that it is applied to a mixture comprising fibres (2) as a first family of components, preferably polyethylene terephthalate-based fibres, and comprising granules (3) as a second family of components, preferably rubber-based granules, in that the length of at least some of the fibres (2) is equal to or greater than a first predetermined reference value (L2), in that the equivalent diameter of at least some of the granules (3) is equal to or less than a second predetermined reference value (L3), strictly lower than the first reference value (L2), and in that, in order to carry out the selective retention phase (S201), a grating (14) is used that is integrated in the containment wall (13) and that forms a screen, the mesh (M14) of which ranges between the first reference value (L2) and the second reference value (L3).

15. Method for recycling a pneumatic tyre comprising a grinding step, during which at least a portion of said pneumatic tyre is reduced into a mixture containing textile fibres (2) and granules (3) made of a rubber-based material and then a separation step, during which a separation method according to any one of Claims 12 to 14 is applied to said mixture.

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