Apparatus for separating the components of a mixture of fibres and granules by beating the mixture by means of an alternating electric field

Abstract

The present invention relates to a separating apparatus (100) intended to separate two families of components (2, 3) of a mixture (1) placed in a receptacle (5) provided with a screen (6), said apparatus comprising a first electrode (7), a second electrode (8), and a generator (10) which generates, between said first electrode and second electrode (7, 8), an alternating electric agitation field (11), capable of alternately projecting all or some of the components (2, 3) of the mixture (1) contained in the receptacle (5) towards or against the first electrode (7) and then towards or against the second electrode (8), in order to generate mechanical shocks on said components (2, 3) which help to break up the mixture (1) within the receptacle (5) and facilitate the passage of components (3) belonging to the second family through the screen (6), while said screen (6) ensures that components (2) belonging to the first family are retained in the receptacle (5).

Description

INSTALLATION FOR SEPARING THE COMPONENTS OF A MIXTURE OF FIBER AND GRANULES BY BEATING THE MIXTURE USING AN ACTING ELECTRIC FIELD

[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 pm and 1 mm for a length between 1 mm and 10 mm, and granules whose equivalent diameter is between 125 pm and 5 mm.

[0005] There are many processes designed to separate the components of a mixture.

[0006] Thus, it is known in particular, for example from document EP-2 937 200, to mechanically separate the components by dry means, by subjecting the mixture to sieving on a vibrating sieve.

[0007] It is also known, for example from document FR-2 943 561, to perform an electrostatic separation of granular components by imparting to the components, through the triboelectric effect, an electrostatic charge whose sign depends on the component family, and by subjecting the components thus charged to a continuous electric field generated between two electrodes, so that each granule is, according to the sign of its charge, selectively attracted by the electrode of opposite sign that corresponds to it.

[0008] While such known methods are generally satisfactory, they may nevertheless suffer from some limitations and drawbacks.

[0009] Such known processes may have limited effectiveness, particularly when dealing with mixtures of very heterogeneous composition which contain granules on the one hand and fibers on the other, because a number of fibers and granules tend to remain agglomerated with each other.

[0010] Furthermore, the energy efficiency of known separation plants is sometimes poor, as a relatively high amount of energy is required to process a given quantity of mixture. For example, when it is necessary to vibrate a sieve, a significant portion of the input energy is dissipated by the sieve's drive mechanism, and even the kinetic energy actually acquired by the sieve is not fully converted into a stirring and agitation action capable of individually agitating the different components of the mixture relative to one another. Ultimately, only a portion of the input energy effectively contributes to the dissociation of the component agglomerates.

[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, in particular for the treatment of mixtures composed of fibers and granules.

[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, in order to separate the components belonging to the first family from the components belonging to the second family, said installation being characterized in that it comprises an electric threshing chamber which includes: - a receptacle designed to receive the mixture and equipped with a sieve, - a first electrode, - a second electrode placed opposite the first electrode at a distance from the latter, - as well as a generator enabling the application of an alternating voltage between the first and second electrodes so as to generate between said first and second electrodes an alternating electric field, called an "electric agitation field", capable of alternately projecting all or part of the components of the mixture contained in the receptacle towards or against the first electrode and then towards or against the second electrode, in order to generate on said components mechanical shocks which contribute to dislodging the mixture within the receptacle and to facilitating the passage of components belonging to the second family through the sieve, while said sieve ensures retention in the receptacle of components belonging to the first family.

[0013] Advantageously, the invention makes it possible to replace mechanically induced hammering, typical of known installations using vibrating screens, with electrically induced hammering.

[0014] Such an installation therefore offers a significantly improved energy efficiency, because the electrical power supplied by the generator, instead of being converted and dissipated into mechanical energy driving the sieve, is directly transmitted to the components themselves, and thus directly and immediately converted into effective movement, and therefore into kinetic energy, of said components.

[0015] Advantageously, the alternating nature of the electric stirring field allows the mixture to be stirred in all directions, exerting on the components of the mixture, and more particularly on each individual component of the mixture, electrical forces which are oriented alternately in one direction and then in the opposite direction, at the rate of the frequency of the alternating electric stirring field.

[0016] Such agitation makes it possible to multiply the number, intensity and frequency of mechanical shocks which the components undergo when said components, under the effect of the alternating agitation movements induced by the electric agitation field, collide with each other or strike any obstacle present in their trajectory, such as one or the other of the first and second electrodes, a wall of the receptacle, or more particularly the sieve.

[0017] This increased number of impacts facilitates the breakdown of component agglomerates, particularly when dealing with agglomerates where fibers and granules are intertwined and / or adhere to one another. Thus, the increased number of impacts causes and promotes the dissociation of the mixture into separate components, thereby improving the efficiency of the sieving process.

[0018] Furthermore, such an installation allows a given quantity of mixture to be processed in a very short time, since the movement of the components is almost instantaneous, as soon as the electric stirring field is activated.

[0019] In this respect, the inventors observed that, unlike known electrostatic separation installations which require first imparting a sufficient electrostatic charge to the components, for example by means of a tribocharger, before being able to then extract the charged components by means of a fixed electric field, excitation by an alternating electric field according to the invention makes it possible to obtain an immediate agitation of the components, which react as soon as one or the other of the components considered is either polarized, that is to say that said component has an overall neutral charge but presents within it an imbalance in the local distribution of charges which gives it the properties of a dipole, or charged, that is to say that said component has a non-zero self-electric charge, positive or negative.Advantageously, the component's reaction to the alternating electric field occurs even if this polarization or charge of the component is slight.

[0020] The phenomenon of polarization and agitation also rapidly amplifies, generalizing to the entire mixture, under the effect of the alternating electric field of agitation, and lasts as long as the alternating electric field of agitation is maintained.

[0021] In other words, the alternating electric field of agitation is sufficient in itself to cause the almost instantaneous movement of the components, according to repeated and relatively disordered movements powerful enough to dissociate the components from each other, even from a mixture whose components are initially weakly polarized or even non-polarized and / or weakly charged or even uncharged.

[0022] Other objects, features and advantages of the invention will become apparent in more detail upon reading the following description, as well as with the aid of the accompanying drawings, provided for illustrative purposes only and not as a limitation, including:

[0023] Figure 1 illustrates, from an overview perspective, an example of an installation according to the invention, in which the receptacle receiving the mixture is formed by a cylindrical sieving drum whose side wall forms both the first electrode and the sieve.

[0024] Figure 2 is a perspective view of the installation of Figure 1, with material being removed along a vertical cutting plane transverse to the central axis of the sieving drum.

[0025] Figure 3 is a detailed front sectional view in the vertical cutting plane of Figure 2 of the electric hammer chamber of the installation of Figures 1 and 2.

[0026] Figure 4 is a longitudinal sectional view, in a vertical section plane containing the central axis of the screening drum, of the installation of Figures 1 to 3.

[0027] Figure 5 illustrates, according to a schematic front view, the principle of adjusting the azimuthal orientation of the second electrode as a function of the direction of rotation of the sieving drum.

[0028] Figure 6 illustrates, in perspective view, an example of a second electrode used by the installation of Figures 1 to 5.

[0029] The present invention relates to a separation installation 100, such as that illustrated in figures 1 to 5, which is intended to receive a mixture 1 containing at least a first family of components 2 and a second family of components 3, in order to separate the components 2 belonging to the first family from the components 3 belonging to the second family.

[0030] The components 2 of the first family are preferably solid components, and more preferably fibers 2, as shown schematically in figure 3.

[0031] The components 3 of the second family are preferably also solid components, and more preferably granules 3, as shown schematically in figure 3.

[0032] That being said, the invention remains potentially applicable to mixtures of very varied components 2, 3, and could for example be used for the separation of the components of a mixture which would contain two families of granules having distinct structures or shapes, and / or distinct dielectric constants, and / or distinct chemical compositions, and / or distinct densities.

[0033] Preferably, the components of the first family will be fibers 2. These fibers 2 will have a thin, elongated shape, preferably substantially cylindrical. For the sake of simplicity, the components 2 of the first family may therefore be referred to as fibers 2 in what follows.

[0034] 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.

[0035] 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.

[0036] Fibres 2 may be made of a natural or synthetic textile material, and more preferably of a polymer or a combination of polymers from among (non-exhaustive list): polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS).

[0037] Preferably, the components of the second family will be granules 3. For the sake of simplicity of description, the components 3 of the second family can therefore be considered as granules 3 in what follows.

[0038] 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 of said granules 3 present in mixture 1 (100% of the total number of granules present), will preferably have an equivalent diameter between 125 pm and 5 mm, and, preferably, a shape factor between 1 and 2.

[0039] 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.

[0040] 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.

[0041] The installation 100 will preferably be designed to be able to separate and recover (at least) fibers 2 having the aforementioned dimensions, and more particularly to be able to sort, by separating them, on the one hand fibers 2 of such dimensions and on the other hand granules 3 having the dimensions mentioned above, which are initially mixed together in the mixture 1.

[0042] 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%, and preferably more than 60%, while the proportion by weight of the granules 3, in relation to the total weight of the mixture 1, represents between 25% and 95%, and preferably less than 40%.

[0043] According to the invention, the installation 100 comprises an electric threshing chamber 4.

[0044] The said chamber 4 is intended to subject mixture 1 to a beating operation, that is to say to subject mixture 1 to successive shocks, here opposite a sieve 6, to separate the components 2 of the first family from the components 3 of the second family.

[0045] This threshing operation is advantageously carried out dry, that is, without the need to add any liquid additive to mixture 1, particularly a liquid solvent, or to immerse said mixture 1 in any solution. The operation can advantageously take place under a gaseous atmosphere, for example, under ambient air, or possibly under a gaseous atmosphere of controlled composition and / or humidity, such as a dry nitrogen atmosphere.

[0046] According to the invention, and as can be clearly seen in particular in Figures 2 and 3, the electric threshing chamber 4 comprises: - a receptacle 5 which is arranged to receive the mixture 1 and which is equipped with a sieve 6, - a first electrode 7, - a second electrode 8 placed opposite the first electrode 7 at a distance from said first electrode 7, - as well as a generator 10 for applying an alternating voltage between the first electrode 7 and the second electrode 8 so as to generate between said first and second electrodes 7, 8 an alternating electric field 11, called the "agitation electric field" 11, capable of alternately projecting all or part of the components 2, 3 of the mixture 1 contained in the receptacle 5 towards or against the first electrode 7 and then towards or against the second electrode 8, in order to generate mechanical shocks on said components 2, 3 which contribute to dislodging the mixture 1 within the receptacle 5 and to facilitating the passage of components 3 belonging to the second family through the sieve 6, while said sieve 6 ensures retention in the receptacle 5 of components 2 belonging to the first family.

[0047] Of course, the receptacle 5 is arranged so that at least part of the mixture 1 contained in the receptacle 5, and preferably all of the mixture 1 contained in said receptacle 5, is located between the first electrode 7 and the second electrode 8, in the air gap 9 which is defined between them by said first and second electrodes 7, 8.

[0048] Advantageously, the alternating electric field of agitation 11, when activated, excites the components 2, 3 present in the air gap 9 and exerts on said components 2, 3 electric forces which are directed in directions which reverse periodically, at the frequency of the alternating electric field, so that said electric forces point alternately towards the first electrode 7 then towards the second electrode 8 and so on, which has the effect of bouncing the components 2, 3 in the receptacle 5, imposing on said components multiple and repeated changes of direction, according to the alternations of the electric field of agitation 11, but also according to the rebounds of the components 2, 3, when said components 2, 3 thus set in motion collide with each other or reach any obstacle within the receptacle 5.

[0049] For ease of representation, the alternations of the electric field of agitation - and therefore the alternations of the forced displacement of components 2, 3 which result from it - are symbolized by a double arrow on figures 2, 3, 4 and 5.

[0050] These agitation movements imparted to components 2, 3, the speed of which depends in particular on the frequency and intensity of the alternating electric agitation field 11, that is to say on the frequency and amplitude of said alternating electric field created by the generator 10, cause multiple and repeated impacts on components 2, 3, and in particular on the agglomerates which mix, in the mixture initially introduced into the receptacle 5, several components 2, 3 belonging to the two families, which has the effect of dislocating said agglomerates, and therefore of facilitating the sieving, within the receptacle 5, of the components 2, 3 thus dissociated.

[0051] More specifically, the beating operation promotes the passage of components 3 of the second family, here granules 3, through sieve 6, because this beating operation shakes the mixture 1, and therefore in particular the components 3 of the second family, in contact with the sieve 6, after said components 3 of the second family have been dissociated from components 2 of the second family, here an entanglement of fibers 2, which initially prevented components 3 of the first family from passing through the M6 ​​mesh of the sieve 6.

[0052] We can thus collect in the sieve 6 a first product PI called "purified", from mixture 1 and enriched in components 2 of the first family, here enriched in fibers 2, that is to say whose content in components 2 of the first family, here the content in fibers 2, is greater than that of the initial mixture 1.

[0053] In principle, different arrangements of the receptacle 5, the sieve 6 and the first and second electrodes 7, 8 can be envisaged, provided that on the one hand the mixture 1 placed in the receptacle 5 is exposed in the gap 9 of the electrodes 7, 8 and therefore subjected to the electric stirring field 11, and that on the other hand the sieve 6 is positioned to receive the moving components 2, 3 carried by the electric stirring field 11 and separated by the beating action which results from the application of said electric stirring field 11.

[0054] Thus, for example, the receptacle 5 containing the mixture 1, and more preferably the sieve 6, will preferably form a wall which is closed on itself around, at least, the second electrode 8. In this way, the mixture 1 will advantageously be beaten inside a confined space, in the enclosure delimited by the receptacle 5 and containing the second electrode 8, without risk of the mixture dispersing outside the receptacle 5, in particular as long as said mixture 1 has not been dissociated by the beating action and subjected to the sieving operation.

[0055] In a particularly preferential way, the sieve 6 will form at least a portion, or even the whole, of the wall of the receptacle 5 surrounding the second electrode 8.

[0056] The second electrode 8 will of course be located at a distance from the wall of the receptacle 5, so as to preserve an available space between said wall of the receptacle 5 and said second electrode 8, to receive the mixture 1 and agitate it.

[0057] In theory, we can use a first electrode 7 and a second electrode 8 which are both distinct from the sieve 6.

[0058] According to one arrangement possibility, it will then be possible to place inside the receptacle 5, and more particularly inside the sieve 6, forming a cage, both the first electrode 7 and the second electrode 8. The components will then be able to alternately strike the first electrode 7 and then the second electrode 8, and fall back, or be projected by rebound, against the sieve 6 which surrounds the air gap 9, and more particularly which extends at least partly below said air gap 9 in order to be able to collect the components 2, 3 by gravity.

[0059] According to another possible arrangement, the first electrode 7 can be placed outside the receptacle 5, the second electrode 8 inside the receptacle 5, preferably vertically above the first electrode 7, so that the wall of the receptacle 5, and more particularly the sieve 6, will extend partly between the two electrodes 7, 8, in the air gap 9. According to such a configuration, the components 2, 3 subjected to the stirring electric field 11 will alternately strike the second electrode 8 and then the wall of the receptacle 5, and more particularly the sieve 6.

[0060] However, according to a particularly preferential arrangement variant, the sieve 6 itself forms the first electrode 7.

[0061] Thus, the first electrode 7 is preferably integrated into the structure of the sieve 6, and more preferably coincident with the structure of the sieve 6.

[0062] The air gap 9 then corresponds to the empty space which extends between the second electrode 8 and the sieve 6, and therefore more particularly between the second electrode 8 and the wall of the receptacle 5 which incorporates the sieve 6.

[0063] Such an arrangement is advantageously particularly simple and compact. It is also relatively insensitive to fouling, and advantageously allows for the highly efficient processing of a large volume of mixture 1.

[0064] Such an arrangement also allows the components 2, 3 of mixture 1 to precipitate and strike the sieve 6, thanks to the action of the stirring electric field 11, and to mix the electrically stirred mixture 1 in direct contact with the sieve 6, which promotes the sieving action that allows the components 3 of the second family, here the granules 3, to selectively escape from the receptacle 5, through the sieve 6, while The components 2 of the first family, here the fibers 2, are retained by the sieve 6 inside the receptacle 5.

[0065] Furthermore, the wall of the receptacle 5, and more particularly the sieve 6, preferably has a concave shape with respect to the second electrode 8, more preferably a curved concave shape, preferably a cylindrical shape whose base forms an arc of a circle or even a complete circle, so as to promote the redirection towards the second electrode 8 of the components 2, 3 subjected to agitation by the alternating electric field 11, in particular when said components 2, 3 rebound against the internal surface of the wall of the receptacle 5, oriented towards the second electrode 8.

[0066] Furthermore, such a hollow shape of the wall of the receptacle 5, and more particularly of the sieve 6, allows, when said wall, respectively said sieve 6, to extend below the second electrode 8, to retain, by simple effect of gravity, the mixture 1 in the gap 9, substantially vertically above the second electrode 8.

[0067] As a guideline, the length of the air gap 9, that is, the distance between the first electrode 7 and the second electrode 8 in the portion of the receptacle 5 receiving the mixture 1, here more specifically the vertical distance between the sieve 6 and the second electrode 8, is preferably between 30 mm and 200 mm, or between 30 mm and 150 mm, for example between 30 mm and 60 mm. Such a distance range allows both, on the one hand, for a sufficient volume of space for handling and movement to process a significant quantity of mixture 1 and, on the other hand, for the application of an electric stirring field 11 of sufficient intensity to drive the components 2, 3 of the desired threshing motion.

[0068] Furthermore, the electric hammering chamber 4 is preferably delimited by casing panels 12 which separate said chamber 4, and therefore in particular the receptacle 5 and the electrodes 7, 8, from the external environment of the installation 100, notably to contain the components 2, 3 of the treated mixture 1 within the installation 100, and thus prevent the dispersion of said components 2, 3 into the environment. The casing panels 12 may include side panels as well as a top cover (the latter having been removed in the figures for better visibility).

[0069] Preferably, the first electrode 7, and more particularly the sieve 6 forming said first electrode 7, is connected to the same ground as the generator 10, and more preferably connected to earth.

[0070] Such an arrangement is particularly simple and reliable, and allows a voltage to be applied to the second electrode 8, the sign of which changes from positive to negative (and vice versa) with each half-cycle, relative to the first electrode 7, which represents the reference potential, here a zero potential. It is thus easy to generate in the air gap 9, relative to the first electrode 7 and therefore more preferentially relative to the sieve 6, an electric field of agitation 11 whose sign alternates at the frequency of the voltage delivered by the generator 10.

[0071] Preferably, the first electrode 7, and more particularly the sieve 6 forming said first electrode 7, is covered with a layer of electrically insulating material.

[0072] The term "electrically insulating material" here refers to a material with a resistivity equal to or greater than 10 10 Qm at a temperature of 300 Kelvin.

[0073] The insulating layer may, for example, take the form of a coating, for example in PTFE or PET, preferably with a thickness between 10 pm and 100 pm, which will be deposited on the core of the electrode 7, itself made of metal, for example in copper alloy, aluminum alloy or stainless steel.

[0074] Advantageously, the insulating layer prevents the formation of electric arcs between the first electrode 7 and the second electrode 8, and more particularly between the sieve 6 and the second electrode 8, which makes it possible to apply a high intensity stirring electric field 11 without risk of damaging the installation 100 or the components 2, 3 of the mixture 1.

[0075] Next, and more specifically when the first electrode 7 is connected to ground, the insulating layer prevents charge exchange between said first electrode 7 and the components 2, 3 that come into contact with the surface of said first electrode 7 during the hammering action. This prevents depolarization or charge loss of components 2, 3 when they touch the first electrode 7, and more specifically the sieve 6. In this way, the effectiveness of the action of the stirring electric field 11 on the said components 2, 3 is preserved and optimized.

[0076] Similarly, the second electrode 8 may optionally be coated with a layer of electrically insulating material.

[0077] According to a particularly preferred configuration, the receptacle 5 is formed, as can be seen in figures 1 to 4, by a sieving drum 13 of cylindrical shape, preferably with a circular base section, said sieving drum 13 being delimited by a tubular side wall 13L which extends along and around a central axis XI 3.

[0078] As an indication, the internal diameter of the sieving drum 13 may preferably be between 200 mm and 1000 mm, for example between 200 mm and 400 mm.

[0079] Preferably, at least a portion of the side wall 13L of the sieving drum 13 forms the sieve 6.

[0080] The sieve 6 may be formed by a grid, or a set of grids, integrated into the side wall 13L, or, as illustrated in Figures 1, 2 and 4, by a series of holes 14 drilled through the radial thickness of the side wall 13L.

[0081] Preferably, the sieve 6 occupies, in azimuth around the central axis X13, a cumulative angular sector of at least 120 degrees, so as to extend over at least one third of the perimeter of the side wall 13L, preferably at least 240 degrees, or even 360 degrees so as to extend over the entire perimeter of the side wall 13L.

[0082] Furthermore, the first electrode 7 is preferably integrated into the side wall 13L of the sieving drum 13.

[0083] The second electrode 8 is then preferably housed inside the sieving drum 13, at a radial distance from the lateral wall 13L which surrounds said second electrode 8.

[0084] The side wall 13L thus delimits a closed enclosure around the central axis X13, and therefore around the second electrode 8, which notably allows the mixture 1 to be kept captive in said enclosure during the threshing action, as already indicated above.

[0085] By "axial", we mean a direction parallel to the direction of the axis under consideration, here the central axis XI 3.

[0086] By "radial", we mean a direction perpendicular to the axis considered, here the central axis XI 3.

[0087] As can be clearly seen in figures 2 and 6, the second electrode 8 can preferably be in the form of a cylindrical profile, obtained by scanning a basic section 8A along a straight segment, called "generator segment" X8, which is normal to said basic section 8A.

[0088] Preferably, the second electrode 8 is positioned within the sieving drum 13 parallel to Central Tax X13, that is, so that its generating segment X8 is parallel to Central Tax XI 3.

[0089] Preferably, the overall dimensions of the base section 8A of the second electrode 8 are such that said second electrode 8 is contained within a dummy gauge cylinder whose central Tax coincides with the generating segment X8 of the cylindrical profile of the second electrode and whose radius is between 25% and 75% of the internal radius of the sieving drum 13, for example between 30% and 45% of the internal radius of the sieving drum 13.

[0090] More preferably, the second electrode 8, when positioned within the installation 100, is contained within a dummy gauge cylinder which is centered on the central X13 and whose radius is between 30% and 75% of the internal radius of the screening drum 13, for example between 50% and 65% of the internal radius of the screening drum 13, so that said second electrode 8 is substantially centered on the base section of the screening drum 13, at a distance from any point on the side wall 13L of the screening drum 13.

[0091] The second electrode 8 and the side wall 13L of the sieving drum 13, and more particularly the second electrode 8 on the one hand and the portion of the side wall 13L which forms the sieve 6 and the first electrode 7 on the other hand, overlap axially, that is to say they occupy, along the central axis XI 3, a common axial range, and preferably an identical axial range, as can be seen in particular in Figure 4.

[0092] As an indication, the second electrode 8, and therefore the air gap 9 defined at the radial level (here at the vertical level) of said second electrode 8 and enabling the electric hammering action, can thus preferably extend over an axial range which represents at least 25%, preferably at least 50%, or even at least 65% of the total axial length of the screening drum 13.

[0093] Furthermore, according to a preferred feature, the installation 100 may include a drive system 15 arranged to drive the screening drum 13 in rotation RI 3 on itself, around its central axis XI 3.

[0094] This drive system 15 is powered by a motor 16, preferably an electric motor 16.

[0095] Advantageously, the rotation RI 3 of the screening drum 13 relative to the frame of the installation 100, and therefore relative to the second electrode 8 which is preferably fixed relative to the frame of the installation 100, allows several useful effects to be obtained.

[0096] The first effect is to ensure additional mechanical mixing of components 2, 3 in contact with the sieve 6, in addition to the beating movements induced by the electric agitation field 11, additional mechanical mixing which promotes the sieving action.

[0097] A second possible effect is a tribo-charging effect, which allows components 2, 3 to be given, by friction, depending on the nature of components 2, 3, an electrostatic charge which will reinforce the electrical forces exerted by the electric field of agitation 11 on the components 2, 3 concerned, and therefore the agitation effect of said components 2, 3.

[0098] A third possible effect is to promote the transport of the mixture along the central axis X13, to allow the evacuation of the first product PI retained by the sieve 6, and, more generally, to allow the treatment of a continuous flow of incoming mixture 1.

[0099] It should be noted that, for this purpose, the central axis X13 of the sieving drum 13 is preferably inclined with respect to the horizontal at a slope of non-zero angle and less than 30 degrees, so that the sieving drum 13 can progressively convey the mixture 1 along the central axis X13 in an upstream-downstream direction which corresponds to the direction of the downward slope.

[0100] The angle of inclination can preferably be adjusted by means of an inclination adjustment mechanism 17, of the type rocker plate 17.

[0101] Preferably, the sieve 6 is located in an upstream section 13 A of the sieving drum 13, while the sieving drum 13 has an outlet 20 in a downstream section 13B.

[0102] Outlet 20 will be used to discharge the components retained by the sieve 6 from the screening drum 13. This outlet 20 may, for example, as shown in Figures 1, 2, and 4, include windows cut through the radial thickness of the side wall 13L in the downstream section 13B. These windows will, of course, be strictly larger than the mesh size M6 of the sieve 6 preceding them along the central axis X13.

[0103] Furthermore, the installation 100 will preferably include a feeding device (not shown), of the type hopper or Archimedes screw, which allows the electric threshing chamber 4 to be supplied with mixture 1, and more particularly to pour said mixture 1 continuously, or in successive batches, into the receptacle 5, here in the upstream portion 13 A of the sieving drum 13.

[0104] Preferably, the installation 100 includes on the one hand a first collector 21 arranged opposite the outlet 20 of the screening drum 13 to collect a first product PI from the mixture and whose content of components 2 of the first family, here the content of fibers 2, is greater than that of the mixture 1, and on the other hand a second collector 22 arranged opposite the screen 6, here below said screen 6, in order to collect a second product P2 from the mixture and whose content of components 3 of the second family, here the content of granules 3, is greater than that of the mixture 1.

[0105] The first and second collectors 21, 22 will preferably be arranged under the receptacle 5, preferably here under the screening drum 13, respectively under the downstream section 13B and under the upstream section 13A of said screening drum 13, so as to be able to collect by gravity the components 2, 3 from the receptacle 5.

[0106] The first and second collectors 21, 22 may take the form of trays, arranged under the sieving drum 13.

[0107] The first and second collectors 21, 22 can each be associated with an extraction conveyor (not shown), such as a belt conveyor, which is arranged to evacuate the product Pl, P2 collected by the collector 21, 22 considered out of chamber 4, and more generally out of the installation 100. Such conveyors will advantageously allow continuous operation of the installation 100.

[0108] According to a preferred feature which may constitute an invention in its own right, the second electrode 8 has, opposite the first electrode 7, or more particularly opposite the sieve 6, a non-planar shape comprising at least a concave portion formed by a re-entrant notch 30, bordered by two protruding lobes 31.

[0109] More preferably, the second electrode 8 may have, as can be clearly seen in figures 2, 3 and 6, two concave portions formed by two adjacent notches 30 delimited by a succession of three lobes 31.

[0110] The inventors have indeed observed that a non-planar, substantially wavy shape of the second electrode, and more particularly a concave shape of the base section 8A alternating one or more hollows (the notches 30) with protruding elements (the lobes 31) promoted the multiplication of impacts and rebounds of components 2, 3 in multiple directions, and therefore promoted the dislocation of the agglomerates.

[0111] The inventors also found that, when processing a mixture of fibers 2 and granules 3, such a form of the second electrode 8 promoted an accumulation, in the hollows of the notches 30, of particularly pure fibers 2, under the action of the stirring electric field 11, which facilitated the evacuation of the granules 3 through the sieve and the formation in the receptacle 5 of a first product PI which was particularly well purified, very rich in fibers 2.

[0112] Preferably, the installation 100 will include one or more adjustment mechanisms allowing the (fixed) position of the second electrode 8 to be changed relative to the first electrode 7, and more particularly allowing the (fixed) position of the second electrode 8 to be changed relative to the central axis X13 of the screening drum 13.

[0113] The installation 100 may include in particular an adjustment mechanism in position 32 which will allow to modify, in translation in a plane normal to the central axis X13, the position of the second electrode 8 with respect to the origin which is formed by the central axis X13, that is to say the eccentricity, positive or zero, of the second electrode 8 with respect to the sieving drum 13, and more particularly which will allow to modify the height of the second electrode 8 with respect to the sieving drum 13, in particular with respect to the portion forming the lowest point of the radially internal face of the sieving drum 13 in the plane considered, and therefore with respect to the surface of the sieve 6 retaining the components.

[0114] Preferably, the installation includes an orientation adjustment mechanism 33 which allows the azimuthal orientation A8 of the second electrode 8 to be modified in roll around an axis parallel to the central axis X13 of the sieving drum 13, and more preferably around said central axis X13 of the sieving drum 13, in order to orient the notch(s) 30 of the second electrode 8 in an oblique direction with respect to the vertical, in the direction which corresponds to the direction of rotation RI 3 of the sieving drum 13, as can be seen in Figure 5.

[0115] Advantageously, the corrugated surface of the electrode 8, and more particularly the notch(s) 30, can thus point, with respect to a vertical reference plane PO containing the central axis X13, towards a side of said vertical reference plane PO which corresponds to the side where the mixture 1 contained in the receptacle 5 tends to accumulate under the effect of the rotation R13 of the sieving drum 13, which makes it possible to orient the electric agitation field 11 towards the area where, potentially, the greatest thickness of mixture 1 is encountered on the sieve 6. This makes it possible to optimize the efficiency of the electric threshing, and more generally the combination of the electric threshing and the rotary mechanical stirring.

[0116] Preferably, the second electrode 8 has a sagittal plane containing the generator segment X8, and with respect to which the lobes 31, and the notch(s) 30, have a symmetrical arrangement.

[0117] The orientation adjustment mechanism 33 will then preferably allow this sagittal plane to be tilted relative to the vertical reference plane PO containing the central axis XI 3 of the sieving drum 13, as can be seen in Figure 5, preferably using a pivot axis which coincides with said central axis XI 3 of the sieving drum 13.

[0118] Preferably, the frequency of the alternating voltage applied by the generator 10, and therefore the frequency of the electric stirring field 11, is chosen to be equal to or greater than 5 Hz, and preferably between 7 Hz and 200 Hz.

[0119] Advantageously, a relatively high frequency causes frequent changes in direction of the electrical forces exerted on components 2, 3, and therefore a very jerky and rapid acceleration and agitation of components 2, 3, which on the one hand increases the frequency of the mechanical shocks suffered by components 2, 3, and on the other hand increases the speed and therefore the kinetic energy of components 2, 3, and consequently the intensity of said shocks, which leads to very efficient dissociation of the agglomerates.

[0120] Preferably, the peak intensity of the alternations of the stirring electric field 11, considered at a point located on a virtual straight line segment corresponding to the shortest distance separating the first electrode 7 from the second electrode 8, here at a point in the air gap 9 in which the mixture 1 exposed to the beating action is located, is between 200 kV / m and 1000 kV / m.

[0121] This allows us to have an electric field of agitation 11 powerful enough to force the alternating, and therefore jerky, movement of the components 2, 3 present in the receptacle 5 and located in the air gap 9, in particular when the air gap 9 has a length within the range of values ​​indicated above.

[0122] The peak amplitude of the alternating voltage applied by the generator 10 between the electrodes 7, 8 will of course be adapted accordingly.

[0123] As an indication, generator 10 will preferably deliver an alternating voltage with a peak value between 10 kV and 60 kV.

[0124] The M6 ​​mesh of the sieve will of course be adapted to the shapes and dimensions of components 2, 3.

[0125] Preferably, the M6 ​​mesh size of the sieve (6) is between 1 mm and 10 mm, and more preferably between 2 mm and 5 mm

[0126] Typically, the holes 14 drilled in the side wall 13A of the sieving drum 13 will have a diameter equal to this M6 mesh.

[0127] Of course, the invention also relates as such to a separation process implementing a beating operation of a mixture 1 of components 2, 3 by an alternating electric field 11.

[0128] Such a process is preferably implemented using an installation 100 according to any of the characteristics described above.

[0129] Thus, the invention relates to a separation process enabling, from 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, the separation of components 2 belonging to the first family from components 3 belonging to the second family, said process comprising for this purpose a supply step (S1), during which the mixture 1 is brought into a receptacle 5 provided with a sieve 6, an electric stirring step (S2), during which the components 2, 3 of the mixture 1 contained in the receptacle 5 are agitated by means of an alternating electric field, called the "electric stirring field" 11, so as to subject said components 2, 3 to mechanical shocks in order to dissociate them from each other,and a sieving step (S3) in which the mixture 1 subjected to the electric beating step (S2) is passed over the sieve 6 in order to retain in the receptacle 5 a first product PI from the mixture 1, which first product PI has a content of components 2 of the first family greater than that of the mixture 1, while a second product P2 from the mixture 1 is discharged through the sieve 6, second product P2 having a content of components 3 of the second family greater than that of the mixture 1.

[0130] As mentioned above, this separation process, and more specifically the (S2) electric hammering step, is carried out by dry means, and aims more specifically to separate components 2, 3 which are in the solid state from each other.

[0131] Advantageously, using an alternating electric field 11 to excite the mixture 1 is particularly efficient and energy-saving, since it immediately triggers the movement of components 2, 3, without requiring prior tribo-loading.

[0132] Preferably, the stirring electric field 11 is produced by applying an alternating voltage between, on the one hand, the sieve 6, forming a first electrode 7, and on the other a second electrode 8 is placed inside the receptacle 5, at a distance from the sieve 6.

[0133] As mentioned above, this allows the process to be implemented using a particularly simple and compact structure, the receptacle 5 forming a kind of cage within which the components are tossed about by the alternating electric field of agitation 11 so as to repeatedly and relatively chaotically strike either the second electrode 8 or the sieve 6 which allows all or part of the components 3 of the second family to be extracted from the receptacle 5.

[0134] Preferably, the process is applied to a mixture comprising as a first component family fibers 2, preferably polyethylene terephthalate, and as a second component family granules 3, preferably rubber-based material.

[0135] Preferably, at least part of the fibers 2 have a length equal to or greater than a first predetermined reference value L2, while at least part of the granules 3 have an equivalent diameter that is equal to or less than a second predetermined reference value L3, strictly less than the first reference value L2.

[0136] A sieve 6 can then preferably be used, the mesh size of which M6 is between the first reference value L2 and the second reference value L3; and more particularly such that: L3 < M6 < L2

[0137] In this case, and in particular in relation to the dimensions of components 2, 3 described above, it will be possible to use a sieve 6 whose mesh M6 is between 1 mm and 10 mm, and more preferably between 2 mm and 5 mm.

[0138] According to a particularly preferred application possibility, the invention relates to a method for recycling a tire tire, said method comprising a grinding step, during which at least a portion of said tire tire, for example all or part of the tread of said tire, is reduced into a mixture 1 containing textile fibers 2 and granules 3 of rubber-based material, then a sorting step during which a separation process according to the invention is applied to said mixture 1, in accordance with what has been described above.

[0139] Of course, the invention is by no means limited to the examples of embodiment described above, the person skilled in the art being able in particular to isolate or freely combine one or the other of the aforementioned characteristics, or to substitute equivalents for them.

Claims

DEMANDS 1. 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), in order to separate the components (2) belonging to the first family from the components (3) belonging to the second family, said installation (100) being characterized in that it comprises an electric threshing chamber (4) which includes: - a receptacle (5) which is arranged to receive the mixture (1) and which is provided with a sieve (6), - a first electrode (7), - a second electrode (8) placed opposite the first electrode (7) at a distance from the latter, - and a generator (10) for applying an alternating voltage between the first electrode (7) and the second electrode (8) so as to generate between said first and second electrodes an alternating electric field (11), called the "agitation electric field" (11), capable of alternately projecting all or part of the components (2, 3) of the mixture (1) contained in the receptacle (5) towards or against the first electrode (7) and then towards or against the second electrode (8), in order to generate mechanical shocks on said components (2, 3) which contribute to dislodging the mixture (1) within the receptacle (5) and to facilitating the passage of components (3) belonging to the second family through the sieve (6), while said sieve (6) ensures retention in the receptacle (5) of components (2) belonging to the first family.

2. Installation according to claim 1 characterized in that the sieve (6) forms the first electrode (7).

3. Installation according to claim 1 or 2 characterized in that the first electrode (7) is connected to the same mass as the generator (10), and more preferably connected to earth.

4. Installation according to any one of the preceding claims characterized in that the first electrode (7) is covered with a layer of electrically insulating material.

5. Installation according to any one of the preceding claims characterized in that the receptacle (5) is formed by a sieving drum (13) of cylindrical shape, preferably of circular base section, said sieving drum (13) being delimited by a tubular side wall (13L) which extends along and around a central axis (X13), in that the installation (100) comprises a drive system (15) arranged to drive the sieving drum (13) in rotation (R13) about itself around its central axis (X13), in that at least a portion of the side wall (13L) of the sieving drum forms the sieve (6), in that the first electrode (7) is integrated into said side wall (13L), and in that the second electrode (8) is housed inside the sieving drum (13), at a radial distance from the side wall (13L) which surrounds said second electrode (8).

6. An installation according to claim 5, characterized in that the central axis (X13) of the sieving drum (13) is inclined with respect to the horizontal at a slope of non-zero angle less than 30 degrees, such that the sieving drum (13) can progressively convey the mixture (1) along the central axis (X13) in an upstream-downstream direction corresponding to the direction of the downward slope, in that the sieve (6) is located in an upstream section (13A) of the sieving drum, while the sieving drum (13) has an outlet (20) in a downstream section (13B), and in that the installation (100) comprises, on the one hand, a first collector (21) arranged opposite the outlet (20) of the sieving drum to collect a first product (PI) from the mixture and whose content of components (2) of the first family is greater than that of the mixture (1), and, on the other hand, a second collector (22) arranged opposite the sieve (6), below said sieve (6),in order to collect a second product (P2) from the mixture and whose content of components (3) of the second family is greater than that of the mixture (1).

7. Installation according to any one of the preceding claims characterized in that the second electrode (8) has, opposite the first electrode (7), a non-planar shape comprising at least one concave portion formed by a notch (30) bordered by two lobes (31), and more preferably two concave portions formed by two adjacent notches (30) delimited by a succession of three lobes (31).

8. An installation according to claim 7 and any one of claims 5 or 6, characterized in that it comprises an orientation adjustment mechanism (33) which allows the azimuthal orientation (A8) of the second electrode (8) to be modified in roll about an axis parallel to the central axis (X13) of the sieving drum (13), and more preferably around said central axis (X13) of the sieving drum, in order to orient the notch(s) (30) of the second electrode (8) in an oblique direction with respect to the vertical, in the direction which corresponds to the direction of rotation (RI 3) of the sieving drum (13).

9. Installation according to any one of the preceding claims characterized in that the frequency of the alternating voltage applied by the generator (10), and therefore the frequency of the electric stirring field (11), is chosen to be equal to or greater than 5 Hz, and preferably between 7 Hz and 200 Hz.

10. Installation according to any one of the preceding claims characterized in that the peak intensity of the alternations of the electric stirring field (11), considered at a point located on a virtual straight line segment corresponding to the shortest distance separating the first electrode (7) from the second electrode (8), is between 200 kV / m and 1000 kV / m.

11. Installation according to one of the preceding claims characterized in that the mesh (M6) of the sieve (6) is between 1 mm and 10 mm, and more preferably between 2 mm and 5 mm.

12. A separation process enabling the separation of components (2) belonging to the first family from components (3) belonging to the second family from 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 process comprising for this purpose a feeding step (S1), during which the mixture (1) is brought into a receptacle (5) provided with a sieve (6), an electric beating step (S2), during which the components (2, 3) of the mixture contained in the receptacle (5) are agitated by means of an alternating electric field (11), referred to as the "electric stirring field" (11), so as to subject said components (2, 3) to mechanical shocks in order to dissociate them from one another,and a sieving step (S3) in which the mixture (1) subjected to the electric beating step (S2) is passed over the sieve (6) in order to retain in the receptacle (5) a first product (PI) from the mixture (1), which first product (PI) has a content of components (2) of the first family higher than that of the mixture (1), while a second product (P2) from the mixture (1) is discharged through the sieve (6), second product (P2) having a content of components (3) of the second family higher than that of the mixture (1).

13. Separation method according to claim 12 characterized in that the electric stirring field (11) is produced by applying an alternating voltage between on the one hand the sieve (6), forming a first electrode (7), and on the other hand a second electrode (8) which is placed inside the receptacle (5), at a distance from the sieve (6).

14. Separation method according to claim 12 or 13 characterized in that it applies to a mixture comprising as a first family of components fibers (2), preferably of polyethylene terephthalate, and as a second family of components granules (3), preferably of rubber-based material, in that at least a part of the fibers (2) have a length equal to or greater than a first predetermined reference value (L2), in that at least a 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 a sieve (6) is used whose mesh size (M6) is between the first reference value (L2) and the second reference value (L3).

15. A process for recycling a pneumatic tire comprising a grinding step, during which at least a portion of said pneumatic tire is reduced into a mixture (1) containing textile fibers (2) and granules (3) of rubber-based material and then a sorting step during which said mixture (1) is subjected to a separation process according to any one of claims 12 to 14.

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