FR3129092A1 - INSTALLATION INTENDED TO SEPARATE IN AN ELECTRICAL FIELD THE COMPONENTS OF A MIXTURE OF FIBERS AND PELLETS USING A TRIBOCHARGER PROVIDED WITH A GRID FOR SELECTIVE CONTAINMENT OF SAID COMPONENTS - Google Patents

Abstract

The invention relates to an installation for separating the components of a mixture containing fibers 2) and granules (3), said installation comprising a tribocharger (4) for giving the components (2, 3) an electrostatic charge, at least a pair of electrodes (5, 6) for generating a separating electric field which conveys the charged components, according to their polarity, to collectors (10, 11), said installation being characterized in that the tribocharger (4) has a confinement grid (14) arranged to retain the components in the tribocharger (4) until said components (2, 3) have reached a sufficient charge, then to allow said components to pass, once charged, into the air gap (7) from which said components (2, 3) reach their collector (10, 11), under the action of the separating electric field. Figure 1

Description

INSTALLATION INTENDED TO SEPARATE IN AN ELECTRIC FIELD THE COMPONENTS OF A MIXTURE OF FIBERS AND PELLETS USING A TRIBOCHARGER PROVIDED WITH A GRID FOR SELECTIVE CONTAINMENT OF SAID COMPONENTS

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

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 part of the granules, with a view to recycling the constituent materials of these components.

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

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

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

In particular, document FR-2 943 561 discloses a process during which a mixture composed of different granules, belonging to two families of different materials, is poured onto a fluidized bed which is located in the lower part of an air gap. bounded by two electrodes of opposite polarity. Said 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 that make up the mixture in the air gap, it gives said granules, by tribo-electric effect, an electrostatic charge whose sign depends on the family to which each granule considered 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 conveys said granule out of the air gap, to a suitable manifold.

If such an installation can give considerable satisfaction in practice, it can however have some limitations and drawbacks.

Indeed, the inventors have found that if such a known installation could be very effective for treating mixtures of relatively homogeneous granules, its effectiveness dropped significantly when the mixture was composed of components heterogeneous in their form, and in particular when the mixture contained on the one hand granules and on the other hand fibers. Indeed, in the fluidized bed, the fibers, lighter and having a relatively high aerodynamic drag, tend to float above the granules, so that the impact number of said fibers with the granules may not be sufficient to giving said fibers a level of electrostatic charge which is sufficient to obtain effective separation by the electric field.

Second, the treadmills forming the electrodes can be relatively expensive to manufacture. Such a conveyor belt arrangement is moreover relatively vulnerable to fouling, since charged components, or even dust, can sometimes insinuate themselves between a conveyor belt and the rollers which drive said conveyor belt, and where appropriate which allow the application to said treadmill of the necessary bias voltage. Such an incident can cause an alteration of said treadmill by deformation, deformation which is potentially detrimental to the control of the electric field. In addition, such an alteration is likely to increase the rate of wear of the treadmill concerned and therefore reduce its lifespan.

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 treatment of mixtures composed of fibers and granules, while having a structure robust, simple and compact.

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 fibres, and a second family of components, preferably granules, said installation comprising a triboelectric charging device, called a "tribocharger", which is arranged to receive the mixture and to give the components of said mixture, by triboelectric action, electrostatic charges which are of opposite polarities depending on whether the components belong to the first family or to 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 "separating electric field", which is intended to direct the charged components, according to their polarity, either towards a first collector intended to collect components from the first family, or respectively to 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 wall of confinement which separates said enclosure from the first and second electrodes and from the first and second collectors, said confinement wall being arranged in such a way that the mixture which is contained in the enclosure is subjected to the action of tribo-electric charging and, simultaneously , exposed to the separating electric field, and said confinement 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 which is sufficient for the said components to escape from the enclosure, crossing the confinement wall through the grid, under the action of the separating electric field, and can thus reach the collector which gives them matches, depending on their polarity.

Advantageously, the fact of interposing between the enclosure and the collectors a confinement wall according to the invention makes it possible to create a buffer zone, formed by the enclosure, in which the mixture is maintained for the duration just necessary and sufficient to confer to 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.

The grid, like a sieve, in fact performs a selection function, by retaining the uncharged or insufficiently charged components inside the enclosure, and thus preventing said components from being released prematurely. in the air gap, and in particular to fall into the air gap under the simple effect of gravity, while this same grid will be capable of allowing these same components to pass once they have been loaded.

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 time, while the permanent immersion of the enclosure in the separating electric field allows said separating electric field to immediately and permanently exert an attractive force on the components, as soon as said components acquire an electrostatic charge.

Thus, more particularly, the permanent immersion of the enclosure, and therefore of the components being loaded contained in 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 their shape.

As such, the invention is in particular perfectly suited to the treatment of heterogeneous mixtures containing fibers and granules, and in particular mixtures containing very variable proportions of fibers relative to the granules.

The inventors have in fact observed that a number of fibres, 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, said fibers are deformed, in particular bend, and thus manage to pass through the grid.

Similarly, the inventors have found that the granules, when they are not charged, generally form agglomerates by adhering to fibers which hinder said granules and thus prevent said granules from crossing the grid, even when the granule considered individually nevertheless has a size smaller than the mesh of the sieve formed by the grid. On the other hand, when the granules reach a sufficient electrostatic charge, the electric field will be able to detach them from the fibers and help said granules to cross the confinement wall, passing through the grid.

Thus, advantageously, the invention has increased efficiency, since it makes it possible to obtain in an almost systematic way an effective separation of the components, then an effective recovery of the said components by the collectors according to the family to which the said components belong, and this almost without generating residues or losses in the form of components which would remain prisoners of the enclosure or respectively which, released in the air gap, would escape collection by the collectors and would fall to the bottom of the installation.

Other objects, characteristics and advantages of the invention will appear in more detail on reading the description which follows, as well as with the aid of the appended drawings, provided for purely illustrative and non-limiting purposes, among which:

There illustrates, in a perspective view, an example of an installation according to the invention, which comprises two pairs of rotating cylindrical electrodes with horizontal axes, forming two capture stages, and whose tribocharger is formed by a cylindrical confinement drum whose the tubular side wall forms the grid which ensures the selective retention of the components of the mixture according to their level of electrostatic charge.

There is a front sectional view of the installation of the , in a vertical plane, substantially normal to the axis of rotation of the confinement drum and to the axes of rotation of the cylindrical electrodes.

There illustrates, according to a partial perspective sectional view, the detail of the arrangement of the collectors of the first stage of electrodes of the installation of FIGS. 1 and 2, with in particular the scrapers making it possible to detach the components captured by the cylindrical electrodes.

There illustrates, according to a schematic graph, the intensity of the separating electric field as a function of altitude, vertically plumb with the axis of rotation of the tribocharger of the installation of FIGS. 1 to 3, in the sagittal plane of the installation, and causes two intensity peaks to appear which correspond to the tightening of the air gap between each of the two pairs of electrodes.

There illustrated, according to the same cutting plan as the , a variant embodiment of the installation which comprises a non-return baffle between the first pair of electrodes and the second pair of electrodes, in order to prevent the rise of the components which are resuspended in the air gap by a fluidized bed located in the lower part of the installation.

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.

Preferably, the components of the first family will be fibers 2, which will have a thin and elongated shape, preferably substantially cylindrical. For simple convenience of description, the components of the first family can therefore be likened to fibers 2 in what follows.

At least a part, preferably the majority of said fibers 2 present in the mixture 1 (that is to say 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 which are present in the mixture 1 will have a length of between 1 mm and 10 mm, while the largest of their transverse dimensions, that is to say the largest of the dimensions considered perpendicular to their length , that is to say typically the diameter in the case of a fiber of cylindrical shape, will be between 10 μm and 1 mm. The installation 100 will preferably be designed to be able to separate and recover (at least) fibers of such dimensions.

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 larger of these two transverse dimensions, that is to say, typically, in the case of a fiber 2 of cylindrical shape, a length at least 5 times, preferably at least 10 times, at least 20 times, even at least 50 times or even 100 times greater than the diameter of the fiber 2 concerned.

The fibers 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).

Preferably, the components of the second family will be granules 3. For simple convenience of description, the components of the second family can therefore be likened to granules 3 in what follows.

At least some 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 will preferably have an equivalent diameter of between 125 μm and 5 mm, and a form factor of between 1 and 2.

By “equivalent diameter”, is meant the diameter that a fictitious sphere would have which would occupy the same volume as the volume occupied by the granule 3 considered.

By "shape factor", we designate the ratio between on the one hand the maximum Féret diameter, that is to say the maximum distance, observable for the granule 3 considered, between two straight lines which are parallel to each other and tangent respectively on opposite sides of said granule 3 considered, and on the other hand the minimum Féret diameter, that is to say the minimum distance, observable for the granule 3 considered, between two straight lines which are mutually parallel and tangent respectively to opposite sides of said considered granule. This form factor makes it possible to give a good indication of the slenderness of the granules 3. For information, it is recalled that a form factor equal to 1 corresponds to a sphere, and that a form factor equal to the root square of 2 is a cube.

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 part of the fibers 2 having the dimensions mentioned above, which are initially mixed with each other in the mixture 1.

Preferably, the installation 100 will make it possible in particular to treat mixtures 1 whose proportion by weight of the fibers 2, relative to the total weight of the mixture 1, represents between 5% and 75%, while the proportion by weight of the granules 3, relative to the total weight of mixture 1, represents between 25% and 95%.

The installation 100 comprises a triboelectric charging device 4, called a "tribocharger" 4, which is arranged to receive the mixture 1 and give the components 2, 3 of said mixture 1, by triboelectric 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).

The tribocharger 4 ensures a mixing of the components 2, 3, so that the 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 confers on the said components 2 , 3 electrostatic charges.

The installation 100 further comprises 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 gap 7 an electric field, called “separating electric field”.

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 therefore fibers 2, or respectively towards a second collector 11 which is separate from the first collector 10 and which is intended to collect components 3 of the second family, here therefore granules 3.

The first electrode 5 is arranged to attract towards it, by the effect of the 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 .

Said first electrode 5 could be separate from the first collector 10 and set back from the first collector 10, with respect to the zone where the charged fibers 2 are released in the air gap 7, so that the fibers 2 which are directed 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.

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 at its surface, as is the case in the variant embodiments of FIGS. 1, 2, 3 and 5.

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

Said second electrode 6 could be separate from the second collector 11 and set back from the second collector 11, with respect to the zone where the charged granules 3 are released in 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.

However, preferably, the second electrode 6 forms an integral part of the second collector 11, and is arranged to receive and capture the granules 2 at its surface, as is the case in the variant embodiments of FIGS. 1, 2, 3 and 5.

Preferably, as clearly visible on the , the tribocharger 4 is located directly above the air gap 7 and so that at least 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 dumped in 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 undergo, simultaneously with gravity, the forces of Coulomb due to the combination of their electrostatic charge and the separating electric field, so that said separating electric field is capable of deflecting said components 2, 3 and conveying them to the collectors 10, 11 where said components are captured.

As such, the first and second electrodes 5, 6 are preferably each located on a different side 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.

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

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

The confinement wall 13 is arranged in such a way that the mixture 1 which is contained in the enclosure 12 is subjected to the action of tribo-electric charging and, simultaneously, exposed to the separating electric field.

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

In addition, the confinement 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 reaches, under the action of the tribocharger 4, an electrostatic charge which is sufficient for said components 2, 3 to escape from the enclosure 12, crossing the confinement wall 13 through the grid 14, under the action of the separator electric field, and can thus reach the collector 10, 11 which corresponds to them, depending on their polarity.

The confinement wall 13, and more particularly the grid 14, advantageously forms 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 , to escape from the enclosure 12, which allows the tribocharger 4 to start the charging action of said components 2, 3 of said components 2, 3 and to continue the charging action of said components 2, 3 as long as necessary, that is to say until said components 2, 3 are sufficiently charged to be released in the air gap 7, and driven by the separating electric field to the collectors 10, 11.

The confinement wall 13 thus defines in a way the border 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 wall confinement 13 and its grid 14, and within which the components 2, 3 are introduced and can be retained for the time for said components 2, 3 to acquire a sufficient electrostatic charge, and on the other hand a second sub-chamber , in which the collectors 10, 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, 11 are not accessible to the components 2, 3 as long as said components 2, 3 are confined in enclosure 12, but become accessible to said components as soon as said components 2, 3 have passed through grid 14 to find themselves in the second sub-chamber, in "free flight" in the air gap 7, and therefore free to reach the collectors 10, 11 under the action of the separating electric field.

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

Advantageously, the segregation effected by the grid 14 between sufficiently charged components 2, 3 and insufficiently charged components 2, 3 makes it possible to guarantee the quality and the purity of the filtered products, that is to say 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 of the sign of their charge, are actually extracted from the enclosure 12, and more particularly torn from the enclosure 12 through the grid 14, then collected by the collectors 10, 11, while the insufficiently charged components 2, 3 cannot not leave the triboloading area.

The grid 14 may have any shape allowing the confinement wall 13 to be opened by defining a network of several through openings which will form as many passages for the components 2, 3, by putting the interior of the enclosure 12 in communication 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.

This mesh, chosen to block the uncharged components but to allow the sufficiently charged components to pass, will be defined as a function in particular of the expected combination of the charge of the components 2, 3 (and therefore of 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.

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

Preferably, and in particular with regard to the dimensions and the preferred nature of the fibers 2 and the 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 5mm.

It will 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 be either too large so that it would prevent the components concerned, even carriers of a high electrostatic charge and therefore subjected to a high Coulomb force, to pass through the mesh M14 of the grid 14, or on the contrary too small for the grid 14 to be able to effectively retain the said components 2, 3, even uncharged, at inside the enclosure 12, against gravity.

However, there always exists, in the mixture 1 chosen to be treated by the installation 100, 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 adapted so that these components, unloaded, and if necessary agglomerated together, are retained by the grid 14 inside the enclosure 12, while these same components 2, 3, once intentionally loaded by the action of the tribocharger 4, at a suitable charge level, will be able to cross this same grid 14 under the action of the separating electric field.

In particular, at least a part, 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 sufficiently flexible material to be able, electrically charged, bend under the action of the Coulomb force exerted by the separating electric field, typically bend in a U, and thus cross the mesh M14 of the grid 14.

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

Of course, in the presence of a mixture 1 of given composition, it is possible to adapt the size of the mesh M14 of the grid 14 to obtain the best possible yield from 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 let the sufficiently charged components 2, 3 pass.

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 the components 2 of the first family , and/or at least 50% by number of the components 3 of the second family, or even at least 80% by number of the components 2 of the first family and/or at least 80% by number of the components 3 of the second family, will present properties, and in particular sizes, allowing them to meet the selectivity criterion, that is to say to be sensitive to the segregation operated by the gate 14, which is blocking for the said components 2, 3 (that is to say retains said components) when these are uncharged or insufficiently charged, and which becomes conductive (that is to say lets said components pass) when these same components have acquired a sufficient charge.

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

We can consider different types of tribochargers 4 to equip the installation 100.

However, preferably, the tribocharger 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 mixing of the mixture. 1 which causes the friction of the components 2, 3 with each other and with the containment wall 13 of the enclosure 12.

Preferably, as can be seen in FIGS. 1, 2, 3 and 5, the tribocharger 4 comprises a cylindrical containment drum 15, preferably of circular base, which is delimited by a tubular side wall 16 which extends along the long and around a central axis X15 forming an angle of less than 30 degrees with the horizontal. Said tubular side wall 16 forms the containment wall 13, and at least a portion of said tubular side wall 16 forms the grid 14.

Advantageously, the implementation of a cylindrical tribocharger 4 gives the installation a simple, compact and robust structure.

Furthermore, by placing the mixture 1 in a tribocharger 4, and more particularly in a containment drum 15, which is lying down and which has a cylindrical shape, preferably a shape of revolution, it is possible advantageously to use the rotation R15 of the drum 15 on itself, around its central axis X15, to achieve the mixing of the components 2, 3, and therefore create or increase the electrostatic charge of said components 2, 3.

This rotation R15 is preferably provided by a motor 17, such as an electric motor 17, driven by a control unit 18.

The rotation R15 of the containment drum 15 on itself, around its central axis X15, is preferably continuous and monotonous, that is to say performed uninterruptedly and always in one and the same direction. Effective agitation of the mixture 1 is thus advantageously obtained, without jolts and without risk of settling of the mixture 1, and this moreover without jerks or vibrations of the tribocharger 4, or excessive noise, which improves the service life, the reliability and ease of use of the installation 100.

The speed of rotation R15 is moderate, so as on the one hand to allow a natural mixing of the mixture 1, by self-collapse and permanent reversal of the mixture on itself, under the joint action of the rotation R15 (which allows the side wall 16 to drive and raise part of the mixture along said side wall, in the direction of rotation R15, seen in a section normal to the axis of rotation X15) and of gravity (which makes fall on the rest of the mixture this part of the mixture raised by the rotation), and on the other hand to avoid a centrifugation effect of the mixture 1 which would tend to compact the said mixture 1 or even to eject prematurely, due to the centrifugal force, of the components 2, 3 not loaded.

Thus, the speed of rotation 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 ms ^-2 , that is i.e. less than 12.75 times the acceleration due to gravity. In practice, for a granule 3 with a mass of the order of 0.15 grams, such an acceleration will generate on said granule 3 a centrifugal force of approximately 0.018 Newtons.

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 speed of rotation R10 will preferably be between 10 rpm and 150 rpm / min, more preferably between 30 rpm and 90 rpm.

The side wall 16 of the containment drum 15 may comprise a rigid perforated frame 20, which serves as a support for mesh panels 21, here curved panels which substantially or even exactly follow the curvature of the side wall 16 of the containment drum 15, which mesh panels 21 marry the windows of the frame 20 so as to form as many portions of the mesh 14.

The supply of the enclosure 12 of the tribocharger 4 can be carried out by any suitable supply system, for example by means of an endless screw, of the Archimedes screw type, which takes the mixture 1 from a neighboring silo to transfer it into the enclosure 12, or even by means of a hopper which pours the mixture 1 into the said enclosure 12 of the triboloader 4.

Furthermore, it will be noted that, optionally, the radially inner face of the side wall 16 of the containment drum 15 may be provided with protuberances, such as blades, which contribute to breaking up and stirring the mixture 1 during the rotation R15, in order to accentuate the phenomena of friction and thus improve the efficiency of the triboloading.

Although it is absolutely possible 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.

This in fact makes it possible to envisage continuous operation of the installation 100, that is to say a continuous supply of the tribocharger 4 with mixture 1, and this with very low energy consumption.

Indeed, the central axis X15, and therefore the containment drum 15, is thus given an inclination which places the entry 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 higher than the altitude of the outlet of the containment drum 15, which in turn corresponds to the base of the cylinder forming the other axial end, opposite , of said containment drum 15 .

Under the combined effect of rotation R15 and gravity, this inclination of the containment drum 15, and more precisely of the side wall 16 of said containment drum 15, makes it possible to ensure progressive and continuous transport of the mixture 1 from the entry to the exit of the containment drum, along the central axis X15.

It will 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, that is to say over the entire extent of its transverse section. , in order to preserve a sufficient vacuum in the upper part of the cylinder 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 of between 25% and 30% of said internal diameter.

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

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 of 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.

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 the said components 3 from the air gap 7 by its rotational movement R6.

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

By "parallel", it is indicated here that the central axes X5, X6 extend in the same vector direction, that is to say that the first central axis X5 and the second central axis X6 are each normal to the same plane reference, here more preferably to the same vertical reference plane, as is the case of the projection plane of the .

The first and second electrodes 5, 6 are counter-rotating preferences. More preferably, the direction of the rotations R5, R6 are such that the tangential speed of the surface of the electrode 5, 6, considered at the narrowest point of the gap 7 (here the point of the surface of said electrodes which is closest to the sagittal reference plane P0), rises vertically in the direction of the tribocharger 4 located above the air gap 7, in the opposite direction to that of the natural fall of the components 2, 3 under the effect of gravity . This makes it possible in particular to secure the transfer of the components 2, 3 out of the air gap 7, by preventing the components 2, 3 captured by the electrodes 5, 6 from accidentally becoming detached and falling towards the bottom of the installation 100.

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

In projection in a horizontal plane, the tribocharger 4, and more particularly the confinement drum 15, extends axially at least partly, preferably entirely, in the axial range which is common to the first electrode 5 and to the second electrode 6. The central axis X15 of the confinement drum 15 is preferably contained in a vertical plane, here the sagittal reference plane P0, which is parallel to the central axes X5, X6 of the electrodes 5, 6 (and therefore which is here perpendicular to the vertical projection plane of the ).

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.

Preferably, the first electrode 5 and the second electrode 6 form between them, at the minimum distance which separates them, a first constriction 24 of the gap 7, first constriction 24 which is located at a first altitude H24, and the installation 100 comprises a third electrode 30 and a fourth electrode 31, also subject to a potential difference, and which form between them, at the minimum distance which separates them, a second constriction 32 of the air gap 7 which is located at a second altitude H32 lower than the first altitude H24, so that the separating electric field successively presents, along the vertical, 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 re-increases to form an intensity trough 51 then to reach a second intensity peak 52 in the second constriction 32, at the second altitude H32, as shown on the .

The width of the first tightening 24 here corresponds 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 of the radius of the second electrode 6.

Similarly, the width of the second narrowing 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.

Particularly preferentially, the enclosure 12 of the tribocharger 4 is located at an altitude, called "release altitude" H12, which is higher than the first altitude H24 of the first tightening 24.

Advantageously, the installation 100 thus has, 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.

In this way, a component 2, 3 which leaves the enclosure 12 through the confinement wall 13 and which falls under the effect of gravity can, if necessary, pass successively through the first capture stage 35 then the second stage. capture 36, and therefore in particular the first intensity peak 50, passing through the first constriction 24, then the second intensity peak 52, passing through the second constriction 32, so that, if said component 2, 3 is too heavy and/or insufficiently charged, relative to its weight or relative to the distance which initially separates said component from the collector 10, 11 which corresponds to it, to be captured by the first upper capture stage 35, then it is possible that said component 2, 3 is captured, in catch-up, by the second lower capture stage 36 . This will ensure a high recovery rate of components 2, 3.

Preferably, 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 in FIGS. 1 and 2, and will have the same polarity as the first electrode 5.

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

Likewise, 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 in FIGS. 1 and 2, and will have the same polarity as the second electrode 6.

The fourth electrode 31 will preferably be associated with a fourth collector 34, distinct 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 form part of said fourth collector 34, being arranged so as to be able to capture the components 3 on its surface.

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

The characteristics described with reference to the first pair of electrodes 5, 6, in particular on 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 .

According to a particularly preferred characteristic, whatever the arrangement of the electrodes 5, 6, 30, 31 and whatever 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 others electrodes 5, 6, 30, 31, components 2, 3 captured on its surface.

The installation 100 thus has a simple and inexpensive structure, which ensures separate evacuation, by capture stage 35, 36 and by polarity, of the various components 2, 3. It is thus possible to obtain ease and good reliability of sorting, and with high throughput.

The collectors 10, 11, 33, 34 may be provided with scrapers 38, located outside the 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 can then either be stored temporarily in a container provided for this purpose, or evacuated by means of a suitable conveyor.

By "outside the air gap 7", we can designate here by convention the region of space which is located on the side opposite the center of the air gap 7, and therefore oriented towards the outside of the installation 100, by relative 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.

According to a particularly simple possibility of implementation, the potential difference applied between the third electrode 30 and the fourth electrode 31 may be identical to the potential difference applied between the first and the second electrode 5, 6. To this end, may in particular connect the first and the third electrode 5, 30 both to the same terminal of the generator 8, while the second and the fourth electrode 6, 31 are both connected to the same other terminal of the generator 8.

As a variant, however, different potential differences could be applied to each pair of electrodes.

As an indication, we can implement an installation with the following dimensional characteristics:
- upper electrodes, that is to say the first and second electrodes 5, 6, each having a diameter, preferably equal, of between 250 mm and 400 mm;
- lower electrodes, that is to say the third and fourth electrodes 30, 31, each having a diameter, preferably equal, of between 250 mm and 500 mm;
- A containment drum 15 having an internal diameter of between 200 mm and 300 mm;
- A smaller distance between the upper electrodes 5, 6, that is to say a first constriction 24, equal to the internal diameter of the containment drum 15 increased by 200 mm;
- a smaller distance between the lower electrodes 30, 31, that is to say a second tightening 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.

Preferably, the installation 100 may comprise position adjustment members 40, 41 making it possible to modify 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.

In particular, as seen in the , it is possible to provide a system of vertical rails 40 making it possible to modify, preferably independently of each other, the altitude of the confinement drum 15, respectively one and/or the other of the altitudes of the electrodes 5, 6, 30 , 31.

Similarly, horizontal rails 41 may 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 with respect to vertical plumb of the tribocharger (here therefore the distance from the reference plane P0).

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.

By “electrically insulating material”, is meant here a material which has a resistivity equal to or greater than 10 ¹⁰ Ω.m at a temperature of 300 Kelvin.

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

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 from the lowest point of all said electrodes, here the low 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 "first tribocharger" 4, is located in an upper part of the installation 100 so that at least a part, preferably at least half, and more preferably all, of the altitude range of the air gap H7 extends below the altitude H12 of the lowest point of the enclosure 12 receiving the mixture 1, that is to say below the release altitude H12 mentioned above.

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 come out of the enclosure 12, at the release altitude H12, benefit of a significant height of fall, which leaves space and time for the electrodes 5, 6, 30, 31 to deviate the trajectory of said components towards the collectors 10, 11, 33, 34.

In all cases, of course, the tribocharger 4, and more particularly the enclosure 12 and its grid 14, however remain placed in the zone of influence of the separating electric field, so that the components 2, 3 are caught by said electric field separator and torn out of the enclosure 12, through the grid 14, immediately charged.

According to a particularly preferential characteristic which may constitute an invention in its own right, in particular whatever the nature of the first tribocharger 4, the installation 100 can then also comprise, in a lower part, directly above the first tribocharger 4 and at an altitude H45 strictly lower than the altitude of said first tribocharger 4, here therefore strictly lower than the release altitude H12, a fluidized bed 45, shown schematically in dotted lines on the , 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 the air gap 7 vertically without being captured by the collectors 10, 11, 33, 34.

Advantageously, the efficiency of the installation 100 is thus further improved, by reducing the losses which would correspond to a residue which would be formed by the components that have fallen from the enclosure but not captured and therefore not sorted after their passage through the installation. 100.

According to one preferential feature which may constitute an invention in its own right, the installation 100 comprises, at an intermediate altitude located between the first upper capture stage 35, formed by the first electrode 5 and the second electrode 6 and the second capture stage 36 , lower, 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 as far as the first capture stage 35.

Said non-return baffle 46 preferably comprises first of all, as can be seen on the , a hopper 47 with convergent walls which is able to collect the components 2, 3 falling from the first capture stage 35 and to direct 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 plumb with the lower opening 48 so as to allow the fall into the second capture stage 36 of the components 2, 3 coming from the hopper 47, while preventing the components 2, 3 resuspended in the second capture stage 36 by the fluidized bed 45 to rise through the lower opening 48 in the direction of the first capture stage 35, and therefore to rise beyond said non-return baffle 46 , and in particular to go up to the first capture stage 35.

Advantageously, there is thus confined in the second capture stage 36, in the air gap delimited by the third and the fourth electrodes 30, 31, the components 2, 3 which were not captured during their first drop and which are resuspended, by the fluidized bed 45, in the lower part of the air gap 7. 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 .

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 distance which horizontally separates the third electrode 30 from the fourth electrode 31. Thus, the deflector 49 forms a sort of hat which covers the majority, or even all, of the lower zone 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 zone of the air gap 7 to leave said lower zone of the air gap.

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

Advantageously, the non-return baffle 46 also makes it possible to prevent the gas flow, here ascending, 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.

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

These walls, and more generally the non-return baffle 46, may be vibrated to prevent the components 2, 3 from adhering to said walls.

Preferably, the generator 8 and the electrodes 5, 6, and where appropriate 30, 31, are arranged so that the intensity of the separating electric field, at the level of the internal face of the grid 14 which retains the components, here in particular in the immediate vicinity of the release altitude H12 or even at the release 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.

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

Furthermore, the choice of a moderate intensity, for example equal to or less than 400 kV/m, will advantageously make it possible to create the separating electric field by means of generators 8 having a maximum voltage of less than 100 kV, and which are therefore relatively little expensive and not very restrictive to implement, in particular in view of the safety standards applicable to such generators 8 in terms of isolation distances.

It will 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 apart by a center distance of 80 cm, which each have a diameter of 30 cm, and which are associated with a containment 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 of between 0 cm and 40 cm above the altitude common to the two central axes X5, X6 of said first and second electrodes.

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

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

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

Such a method can preferably be implemented by means of an installation 100 as described above.

It will be noted that the method according to the invention preferentially and advantageously constitutes a method of separation by the dry route, which requires neither the use of solvent nor the treatment of the components 2, 3 by any liquid solution.

The separation method 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 between them an air gap 7 so as to generate in said gap 7 an electric field called "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- electrical, electrostatic charges which are of opposite polarities depending on whether the components 2, 3 belong to the first family or to the second family, then a sorting step (S3) during which the separating electric field is used to direct the components 2 charged components of the first family to a first collector 10 which captures said components 2 of the first family, and to direct the charged components 3 of the second family to a second collector 11 which is separate from the first collector 10 and which captures said components 3 of the second family.

According to the invention, the step (S2) of electrostatic charging comprises a phase (S201) of selective retention, during which the mixture 1 is placed inside an enclosure 12 which is separated from the first and second electrodes 5, 6 and first and second collectors 10, 11 by a confinement wall 13, and said mixture 1 present in the enclosure is subjected to tribo-electric action, in the presence of the separating electric field, and, according to whether or not the electrostatic charge level reached by certain components 2, 3 corresponds to a charge level deemed sufficient, said components 2, 3 are authorized to leave enclosure 12 so that said components 2, 3 can reach 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 enclosure, by retaining them by means of the confinement 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 level of charge deemed sufficient to be able to be released from the enclosure 12, intended for the collectors 10, 11.

Thus, the sorting step (S3) is preceded by a step (S201) of selective retention which makes it possible to maintain, here by means of the grid 14, the components 2, 3, initially uncharged or lightly charged, in the zone buffer formed by the enclosure 12, until these same components have acquired a charge which is sufficient to trigger their extraction from the enclosure 12, through the grid 14, and their release into the air gap 7, d 'where 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 the said grid 14, advantageously makes it possible to automatically ensure, 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 are met for the separating electric field to convey said component to the collector 10, 11 which corresponds to it.

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, under said enclosure 12, at least two peaks of intensity 50, 52 staged vertically and separated by an intensity hollow 51, so as to form a first upper capture stage 35, with which at least part of the components 2, 3 coming from the enclosure 12 are captured, then a second lower capture stage 36 with which at least some of the components 2, 3 coming from the enclosure 12 and not captured by the first upper capture stage 35 are captured.

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

Advantageously, such a stepped structure considerably limits the fall of components 2, 3 in the bottom of the installation, and promotes efficient evacuation of each family of components, with a good flow, because said evacuation is distributed over two floors 35, 36 , and thus affects the capture and evacuation of the same family of components two stages 35, 36 of capture and therefore several collectors working simultaneously.

Preferably, the separation process applies to a mixture 1 which comprises as first family of components fibers 2, preferably based on polyethylene terephthalate, and as second family of components granules 3, preferably based on rubber. At least part of the fibers 2, preferably the majority of the fibers 2 (that is to say 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 a part of the granules 3, preferably the majority of the granules (that is to say more than 50% of the number of granules present), or even all of the granules 3, present an equivalent diameter which is equal to or less than a second predetermined reference value L3, strictly less than the first reference value L2.

Advantageously, it is then possible to use, to carry out the phase (S201) of selective retention, a grid 14 which is integrated into the confinement wall 13 and which forms a sieve whose mesh M14 is between the first reference value L2 and the second reference value L3, i.e.: L3 < M14 < L2

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

Of course, the invention is in no way limited to the exemplary embodiments described in the foregoing, the person skilled in the art being in particular able to isolate or freely combine one or the other of the aforementioned characteristics. , or to substitute equivalents for them.

Claims (14)

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 ), said installation (100) comprising a tribo-electric charging device (4), called a "tribocharger" (4), which is arranged to receive the mixture (1) and give the components (2, 3) of said mixture, by triboelectric action, electrostatic charges which are of opposite polarity depending on whether the components (2, 3) belong to the first family or to the second family, said installation (100) further comprising 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 an electric field, called "separating electric field", which 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 to a second collector (11) separate from the first collector (10) and intended to collect components (3) of the second family, said installation (100) being characterized in that the tribocharger (4) receives the mixture (1) inside an enclosure (12) which is delimited by a confinement wall (13) which separates said enclosure (12) from the first and second electrodes (5, 6) and first and second collectors (10, 11), said confinement wall (13) being arranged in such a way that the mixture (1) which is contained in the enclosure (12) is subjected to the action of tribo- electric and, simultaneously, exposed to the separating electric field, and said confinement wall (13) being provided with a grid (14) which 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 action of the tribocharger (4), an electrostatic charge which is sufficient for said components (2, 3) to escape from the enclosure (12), crossing the confinement 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, depending on their polarity. Installation according to Claim 1, characterized in that the triboloader (4) comprises a cylindrical containment drum (15) which is delimited by a tubular side wall (16) which extends along and around a central axis (X15) forming with the horizontal an angle of less than 30 degrees, preferably non-zero, tubular side wall (16) which forms the confinement wall (13) and of which at least a portion forms the grid (14). Installation according to Claim 1 or 2, characterized in that the first electrode (5) is formed by a cylindrical electrode mounted in rotation (R5) around a first horizontal central axis (X5) and the surface of which forms a portion of the first collector (10) by being able to collect the components (2) of the first family and to evacuate the 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) 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), second cylindrical electrode (6) whose surface forms a portion of the second collector (11) 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). Installation according to one of the preceding claims, characterized in that the first electrode (5) and the second electrode (6) form between them, at the minimum distance which separates them, a first constriction (24) of the air gap (7) located at a first altitude (H24), in that the installation (100) comprises a third electrode (30) and a fourth electrode (31), also subject to a potential difference, and which form between them at least distance which separates them, a second constriction (32) of the gap (7) which is located at a second altitude (H32) lower than the first altitude (H24), so that the separating electric field successively presents, according to the vertical , a first intensity peak (50) in the first tightening (24), at the first altitude (H24), then an intensity which, between the first altitude (H24) and the second altitude (H32) first decreases then then re-increases to form an intensity trough (51) 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 the "release altitude" (H12), which is higher than the first altitude (H24) of the first tightening (24). Installation according to Claims 3 and 4, characterized in that the third and fourth electrodes (30, 31) are also each formed by a cylindrical electrode (30, 31) mounted in rotation (R30, R31) about its central axis (X30, X31) horizontal, and in that each of the first, second, third and fourth electrodes (5, 6, 30, 31) 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 gap (7), independently of the other electrodes (5, 6, 30, 31), the components (2, 3) captured on its surface . Installation according to one 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 to prevent an exchange of charges from the electrode (5, 6, 30, 31) with the components (2, 3) adhering to its surface. Installation according to one of the preceding claims, characterized in that the electrodes (5, 6, 30, 31) which define the separating electric field occupy, as a whole, an altitude range (H7) called the "altitude range of the air gap" (H7) which extends from the altitude of the lowest point of all said electrodes to the highest point of all said electrodes, in that the tribocharger (4), called "first tribocharger" (4), is located in an upper part of the installation (100) so that at least part, preferably at least half, and more preferably all, of the altitude range of the air gap ( H7) 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 , plumb with the first tribocharger (4) and at an altitude (H45) strictly lower than the altitude of said first tribocharger (4), a fluidized bed (45) which forms a second tribocharger (45) capable of electrically recharging and to return in suspension in the gap (7) the components (2, 3) of the mixture (1) which would have fallen from the first tribocharger (4) and would have crossed the gap (7) vertically without being captured by the collectors (10 , 11, 33, 34). Installation according to Claim 7 and one of Claims 4 or 5, characterized in that it comprises, at an intermediate altitude situated between a first upper capture stage (35), formed by the first electrode (5) and the second electrode (6) and a second capture stage (36), lower, formed by the third electrode (30) and the fourth electrode (31), a non-return baffle (46) which is arranged to allow passage to the second capture stage (36) components (2, 3) not captured by the first capture stage (35), while preventing components (2, 3) being resuspended in the second capture stage (36) by the bed (45) to rise beyond said non-return baffle (46), said non-return baffle (46) preferably comprising for this purpose first of all a hopper (47) with converging walls which is capable of collecting the components (2, 3) dropping from the first capture stage (35) and directing said components (2, 3), through a lower opening (48), towards the second capture stage (36), then a deflector ( 49) diverges, which is placed under the hopper (47) plumb with the lower opening (48) so as to allow the fall into the second capture stage (36) of the components (2, 3) coming from the hopper (47), 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 stage capture (35). Installation according to one of the preceding claims, characterized in that the generator (8) and the electrodes (5, 6, 30, 31) are arranged so that the intensity of the separating electric field, at the level of the internal face of the grid (14) which retains the components (2, 3), 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. Installation according to one of the preceding claims, characterized in that 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. 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, said method comprising for this purpose 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 between them an air gap (7) so as to generate in said air gap an electric field called "separating electric field", a step ( S2) of electrostatic charging of the mixture (1), during which components (2, 3) of the mixture are given, by tribo-electric action, electrostatic charges which are of opposite polarities depending on whether the components belong to the first family or to 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 the said components (2 ) of the first family, and for directing the charged components (3) of the second family to a second collector (11) which is separate from the first collector (10) and which captures said components (3) of the second family, said method being characterized in that the electrostatic charging step comprises a phase (S201) of selective retention, during which the mixture (1) is placed inside an enclosure (12) which is separated from the first and second electrodes (5, 6) and first and second collectors (10, 11) by a confinement wall (13), and said mixture (1) present in the enclosure (12) is subjected to the tribo- electric, 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 level of charge deemed sufficient, said components (2, 3) are authorized to leave the enclosure (12) so that the said components can reach the collectors (10, 11) under the action of the separating electric field, or on the contrary the said components (2, 3) are temporarily prevented from leaving the enclosure (12) , retaining them by means of the confinement wall (13), and continuing the tribo-electric action on the said components (2, 3), until these same components (2, 3) have acquired a charge electrostatic with a level of charge deemed sufficient to be able to be released from the enclosure (12), intended for the collectors (10, 11). Separation process according to Claim 11, characterized in that a separating electric field is created which extends at least in part below the enclosure (12), and which has, under the said enclosure, at least two peaks of intensity (50, 52) staged vertically and separated by an intensity trough (51), so as to form a first upper capture stage (35), with which at least some of the components (2, 3) are captured coming from the enclosure (12), then a second lower capture stage (36) with which at least some of the components (2, 3) coming from the enclosure (10) and not captured by the first upper stage are captured capture (35). Separation process according to Claim 11 or 12, characterized in that it applies to a mixture comprising, as the first family of components, fibers (2), preferably based on polyethylene terephthalate, and, as the second family of components, granules ( 3), preferably rubber-based, in that at least part of the fibers (2) have a length equal to or greater than a first predetermined reference value (L2), in that at least part 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), and in that one uses, to carry out the phase (S201 ) for selective retention, a grid (14) which is integrated into the confinement wall (13) and which forms a sieve whose mesh (M14) is between the first reference value (L2) and the second reference value ( L3). Process for recycling a pneumatic tire comprising a grinding step, during which at least a portion of said pneumatic tire is reduced to a mixture containing textile fibers (2) and granules (3) of rubber-based material then a separation step during which a separation process according to any one of claims 11 to 13 is applied to said mixture.