Plant and method for recycling photovoltaic panels and apparatus for separating glass and silicon fragments

Abstract

The present invention relates to an apparatus 40 for separating glass fragments 30 and silicon fragments 24, comprising a vibrating sieve 42, first collecting means 44 and second collecting means 46. The sieve comprises a plurality of bars 48, each of which defines its own axis r, having a cross section defining at least two edges 50 arranged on opposite sides with respect to the axis r. The bars have axes r parallel to each other and inclined by an angle a comprised between 10° and 45° with respect to the horizontal plane; the distance dmin between two adjacent bars is defined by the respective edges, and is comprised between 0.2 mm and 2 mm. The invention further relates to a plant 20 comprising such an apparatus and a method for separating silicon and glass fragments by means of sieving.

Description

[0001] PLANT AND METHOD FOR RECYCLING PHOTOVOLTAIC PANELS AND APPARATUS FOR SEPARATING GLASS AND SILICON FRAGMENTS

[0002] TECHNICAL FIELD

[0003] The present invention relates to the field of plants and methods for recycling photovoltaic panels. In particular, the invention relates to a plant and a method for recycling photovoltaic panels and to an apparatus for separating glass and silicon fragments, used in such a plant and such a method.

[0004] STATE OF THE ART

[0005] Photovoltaic panels represent a strategic resource in what is called the energy transition, i.e. in the transition from the use of non-renewable energy sources, mainly consisting of fossil hydrocarbons, to the exploitation of renewable energy sources.

[0006] The massive installation that has been promoted since the 1990s will soon result in the need to dispose of a large amount of exhausted photovoltaic panels. The service life of photovoltaic panels is in fact estimated at around 25-30 years, after which the panel must be replaced because it is no longer productive. Early replacements may be desirable due to the availability of newly developed photovoltaic panels with higher efficiency, while a proportion of panels must be replaced early due to failures or damages. It is estimated that around 1 billion photovoltaic panels are currently installed in Europe, for a total mass of 25 million tonnes of material to be recycled.

[0007] The correct disposal of the panels is therefore an integral part of the challenge of the energy transition. However, such disposal is not simple and presents considerable technical difficulties.

[0008] The most common photovoltaic panels are obtained by hot-rolling a plurality of different layers. The following is a description of a generic construction process for a common photovoltaic panel. Firstly the cover layer is prepared, made of top-quality, high-transmittance tempered glass, which will represent the upper surface of the panel, the one which is exposed to solar radiation during use. An EVA (Ethylene Vinyl Acetate) film is spread on the front glass, on which the silicon photovoltaic cells are placed, complete with the relative conductive metal tracks. The conductive tracks take the form of strips and are typically made of copper, but can also be made of aluminium or silver. A further EVA film is then spread over the photovoltaic cells and finally the support layer (or backsheet) is placed, usually made of a polymer with low thermal expansion such as, for example, Polyvinylfluoride (PVF) or Polyethylene Terephthalate (PET) or, in the case of the more recent double-sided modules, glass. The resulting sandwich is pressed under heat (approx. 150°C) so that the EVA films become fluid and completely seal all the components of the panel. Then an electrical junction box is connected and the panel is enclosed in a structural frame, typically made of aluminium, which has the function of sealing, protecting and stiffening the panel.

[0009] When disposing of the exhausted panel, the separation of the different materials is a problem in economic and environmental terms. Heat and / or chemical and / or mechanical processes are available which allow separating the different layers of the panel, e.g. by degrading the EVA.

[0010] Among such methods, the heat processes (whether based on polymer combustion or pyrolysis) allow the recovery of the photovoltaic cells in the form most similar to the original one with the advantage of a possible better value appreciation of the silicon and silver.

[0011] Patent EP3993067B1 describes a method for recycling photovoltaic panels of the type described above. After removing the frame, the method involves treating the sandwich comprising a glass, a first insulating junction sheet, the photovoltaic cells, a second insulating junction sheet and a back sheet. In accordance with such a method, the sandwich is arranged so that the glass sheet faces downwards and the backsheet is arranged upwards, preferably mechanically divided into parts. The sandwich is then introduced into a furnace where it undergoes a heat treatment which breaks it down into a complex of materials comprising glass fragments, photovoltaic cell fragments and metal strips. More in particular, the heat treatment is carried out by generating a directional flow of heat which laps and heats the backplate of the panel. The directional flow of heat is such that it causes the complete combustion of the insulating EVA junction boards.

[0012] The fragments resulting from the breaking of the photovoltaic cells consist predominantly of silicon but also comprise silicon nitride and / or metal contacts in silver and / or aluminium. For simplicity of description, such fragments will be indicated hereafter simply as silicon fragments, implying the presence of small amounts of silicon nitride, silver, and / or aluminium therein.

[0013] The method of patent EP3993067B1 allows to obtain great advantages with respect to other methods which have been proposed. In fact, by limiting the combustion of the backsheet, it minimises the energy expenditure and harmful emissions associated with combustion.

[0014] At the end of the heat treatment, whether combustion or pyrolysis, there is still the need to separate the glass fragments from the silicon fragments and metal contacts.

[0015] Patent EP389296B1 proposes a solution in which, after separating the metal contacts by means of an initial comb sieve, the glass and silicon fragments are slid along an inclined plane on which slots are arranged, sized to allow the passage of silicon fragments but not glass fragments. Thereby, the silicon fragments fall through the slots and are collected in a container below, while the glass fragments slide along the inclined plane to be collected in a separate container.

[0016] The solution of EP389296B1 describes a very effective separation method between glass and silicon, but the proposed apparatus is not without disadvantages. The slots arranged along the inclined plane must necessarily be very thin to prevent the passage of glass fragments and allow silicon fragments to pass through. For this reason, with prolonged use of the apparatus, it often occurs that glass fragments of particularly fine grain size do not pass through, but get trapped in the slots. When this happens, more glass and silicon fragments gradually accumulate, by successive aggregation, until the slot is completely blocked, requiring the plant to be shut down and cleaned.

[0017] Furthermore, the geometry of the apparatus described in EP389296B1 has two possible operating conditions. In a first case, the glass fragments flow over the conveyor elements defining the slots; however, this is only possible if they have sufficient speed or due to high vibrations imposed on the apparatus. In fact, the conveyor elements need to be thick enough to guarantee the correct opening of the respective slit, which prevents the glass fragments from easily passing through them. In this case, the silicon fragments could then also roll, avoiding the slot of the apparatus. In a second case, the glass fragments are diverted by the conveyor elements. However, this implies that all the glass must slide along the slots defined by the conveyor elements, risking interfering with other fragments coming from above. This second operating regime requires an apparatus with a very large surface area, faced with low productivity.

[0018] The need is therefore felt for an apparatus, a plant and a method for recycling photovoltaic panels which guarantees improved efficiency with respect to the known solutions.

[0019] AIMS AND SUMMARY OF THE INVENTION

[0020] An aim of the present invention is to overcome the drawbacks of the prior art.

[0021] In particular, a task of the present invention is to provide an apparatus, a plant and a method for recycling photovoltaic panels with improved efficiency with respect to the known solutions.

[0022] Furthermore, a task of the present invention is to provide an apparatus, a plant and a method for recycling photovoltaic panels which allow the reliable and efficient separation of glass from the silicon of the photovoltaic panel.

[0023] Further, a task of the present invention is to provide an apparatus, a plant and a method for recycling photovoltaic panels which is simple and inexpensive to manufacture and operate.

[0024] Finally, a task of the present invention is to provide an apparatus, a plant and a method for recycling photovoltaic panels which, in addition to the described advantages, allows the functionality of the known solutions to be maintained.

[0025] These and other aims and tasks of the present invention are achieved by an apparatus according to claim 1, by a plant according to claim 6, and by a method according to claim 9.

[0026] In accordance with a first aspect, the invention relates to an apparatus for separating glass fragments and silicon fragments. The apparatus comprises a vibrating sieve, first collecting means and second collecting means, wherein the sieve comprises a plurality of bars, each one defining its own axis r, the cross section of which defines at least two edges arranged on opposite sides with respect to the axis r.

[0027] The bars are arranged so that the respective axes r are parallel to each other and are inclined by an angle a comprised between 10° and 45° with respect to a horizontal plane. Furthermore, the distance dmin between two adjacent bars is defined by the respective edges and is comprised between 0.2 mm and 2 mm.

[0028] Thanks to the described structure, the apparatus of the invention enables the efficient separation of the silicon fragments from the glass fragments.

[0029] Preferably, the sieve can assume a working configuration and a maintenance configuration; in the maintenance configuration, the distance dmax between two adjacent bars is greater than dmin.

[0030] The possibility of bringing the sieve into the maintenance configuration allows to prevent or solve problems arising from the clogging of the slots of the sieve itself.

[0031] Preferably, the bars have a polygonal cross section.

[0032] Preferably, the bars have a square cross section.

[0033] The square cross section allows each bar to assume as many as four different, fully equivalent operating positions. This feature allows to distribute the wear and tear caused by the rubbing of the glass fragments, and thus to extend the service life of the bars.

[0034] Preferably, the bars are tubular.

[0035] The tubular structure of the bars allows to limit the mass and maintain high mechanical characteristics, especially in terms of flexural and torsional stiffness.

[0036] Preferably, the cross section of the bars has a side I comprised between 40 mm and 60 mm.

[0037] The tests carried out by the Applicant have shown how such characteristic bar dimensions are particularly effective in ensuring the separation of the photovoltaic cell fragments while limiting the surface area of the sieve.

[0038] Preferably, one or more bars are configured to rotate about an axis parallel to its own axis r to facilitate the removal of glass fragments and silicon fragments trapped between the bars.

[0039] This configuration resulted to be particularly simple in construction and effective in operation for the removal of any glass or silicon fragments trapped between the bars.

[0040] In some embodiments, the apparatus of the invention comprises at least one blade sliding between two adjacent bars.

[0041] This solution in turn allows any glass or silicon fragments trapped between the bars to be effectively removed.

[0042] In some embodiments, the apparatus of the invention further comprises a second vibrating sieve, placed upstream of the first sieve and similar thereto. In the second sieve, the distance dmin between two adjacent bars and defined by the respective edges is comprised between 1 mm and 2.5 mm.

[0043] The presence of the second sieve, upstream of the first sieve, allows the apparatus of the invention to also remove any metal strips present between the glass and silicon fragments. In such a case, in fact, the glass fragments are immediately removed from the second sieve, while the metal strips and silicon fragments reach the first sieve, where they are in turn separated.

[0044] In accordance with a second aspect, the invention relates to a plant for recycling photovoltaic panels configured to treat a sandwich comprising silicon photovoltaic cells and metal strips embedded in an EVA layer, and enclosed between a front glass and a back support panel, which can be made of glass or polymer material. The plant comprises: a furnace configured to completely consume the EVA by means of combustion or pyrolysis; an apparatus for separating the metal strips from the flow of glass and silicon fragments; and an apparatus for separating glass fragments and silicon fragments in accordance with the above.

[0045] The plant for recycling photovoltaic panels thus configured allows to best exploit the features of the apparatus for separating glass fragments and silicon fragments and is therefore particularly efficient.

[0046] Preferably, the plant further comprises a screen for removing fine particulate, preferably placed upstream of the sieve.

[0047] The arrangement of the screen, particularly upstream of the sieve, allows to remove fine particulate, which is the major cause of clogging of the sieve slots. This thereby prevents many problems and results in more efficient operation with fewer interruptions.

[0048] In accordance with a third aspect, the invention relates to a method for separating glass and silicon fragments during the recycling of photovoltaic panels. The method comprises the steps of: arranging an apparatus for separating glass fragments and silicon fragments, in accordance with the above; arranging a flow of glass fragments and silicon fragments mixed together; and separating the silicon fragments from the glass fragments by means of sieving.

[0049] The method of the invention is particularly simple and effective, especially thanks to the use of sieving. Furthermore, such a method allows to best exploit the features of the apparatus of the invention.

[0050] Further features and advantages of the present invention will be more evident from the description of the accompanying drawings.

[0051] BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The invention is described hereinbelow with reference to certain examples provided by way of non-limiting example and illustrated in the accompanying drawings. These drawings illustrate different aspects and embodiments of the present invention and reference numerals illustrating structures, components, materials and / or similar elements in different drawings are indicated by similar reference numerals, where appropriate. Moreover, for clarity of illustration, certain references may not be repeated in all drawings.

[0053] Figure 1 is a schematic side view of a plant for recycling photovoltaic panels comprising a sieve for separating glass fragments from silicon fragments, in accordance with the invention;

[0054] Figure l.a is an enlarged schematic view of the detail indicated with A in Figure 1;

[0055] Figure 2 is a perspective front view of a sieve in accordance with the invention;

[0056] Figures 3 to 6 are various perspective views of a sieve in accordance with the invention;

[0057] Figure 7 shows a detail of the back end of a sieve in accordance with the invention;

[0058] Figure 8 shows a detail of the front end of a sieve in accordance with the invention;

[0059] Figure 9 schematically shows a section made along the line IX-IX of Figure 8;

[0060] Figure 10 shows the section of Figure 9, where the sieve is in a maintenance configuration;

[0061] Figure 11 schematically shows an axonometric view of a sieve in accordance with the invention, in a working configuration; Figures 12 to 14 schematically show axonometric views of some sieves, all similar to that of Figure 11, each in its maintenance configuration;

[0062] Figures 15 to 18 schematically show some possible variations of the section of a sieve in accordance with the invention;

[0063] Figure 19 is a schematic side view of a plant similar to that in Figure 1, in accordance with the invention;

[0064] Figure 20 schematically shows a partial axonometric view from above of an apparatus in accordance with the invention; and

[0065] Figure 21 schematically shows a partial axonometric view from below of an apparatus in accordance with the invention.

[0066] DETAILED DESCRIPTION OF THE INVENTION

[0067] While the invention is susceptible to various modifications and alternative constructions, certain preferred embodiments are shown in the drawings and are described hereinbelow in detail. It must in any case be understood that there is no intention to limit the invention to the specific embodiment illustrated, but, on the contrary, the invention intends covering all the modifications, alternative and equivalent constructions that fall within the scope of the invention as defined in the claims.

[0068] The use of "for example", "etc.", "or" indicates non-exclusive alternatives without limitation, unless otherwise indicated. The use of "comprises" and "includes" means "comprises or includes, but not limited to", unless otherwise indicated.

[0069] The plant and sieve of the invention are intended to operate in the presence of the acceleration of gravity g. In the following discussion, it is assumed that the terms "vertical" and "horizontal" are uniquely defined according to g. It is also assumed that the terms "high", "upper" and the like are also defined according to g with respect to the terms "low", "lower" and the like.

[0070] The plant and the sieve of the invention define a material flow, in particular, a sandwich derived from a photovoltaic panel enters the plant at one end and glass and silicon fragments exit at the opposite end. With respect to the direction of such a material flow, terms such as "before", "upstream" and the like are understood to be unambiguously defined with respect to terms such as "after", "downstream" and the like.

[0071] With reference to Figure 1, a plant for recycling photovoltaic panels 20 is schematically illustrated. The plant 20 is configured to treat the sandwich 22 derived from the photovoltaic panel from which the aluminium frame and junction box have been removed. As is known, the sandwich 22 comprises a layer of photovoltaic cells of silicon 24 and metal strips 26 embedded in a layer of EVA 28, the whole enclosed between a front glass 30 and a back support panel 32, usually made of glass or PET and / or PVF (see in particular Figure l.a). The plant 20 comprises a furnace 34 in which the sandwich 22 is subjected to heat treatments which eliminate the EVA 28 for example by combustion or pyrolysis. The plant 20 can further comprise a fragmentation station 36 configured to fragment the front glass 30 and / or the photovoltaic cells 24 and / or the back support panel 32 of the sandwich 22. This fragmentation station 36 can be placed either upstream or downstream of the furnace 34, or further, two fragmentation stations 36 can be arranged, one upstream and one downstream of the furnace 34.

[0072] As the person skilled in the art can well understand, it is important during such treatments that the metal strips 26 remain substantially intact. Downstream of the furnace 34 and the possible fragmentation station 36, the plant 20 comprises an apparatus 38 for separating the metal strips 26 from the flow of glass 30 and silicon 24 fragments. Finally, downstream of the apparatus 38 for separating metal strips 26, the plant 20 comprises an apparatus 40 for separating glass fragments 30 and silicon fragments 24, which constitutes the first aspect of the present invention.

[0073] The apparatus 40 for separating glass fragments 30 and silicon fragments 24 in accordance with the invention comprises a vibrating sieve 42, first collecting means 44 and second collecting means 46. In the apparatus 40 of the invention:

[0074] - the sieve 42 comprises a plurality of bars 48, each defining its own axis r; and

[0075] - the bars 48 have a cross section defining at least two edges 50 arranged on opposite sides of the axis r;

[0076] - the bars 48 are arranged so that the respective axes r are parallel to each other;

[0077] - the bars 48 are arranged so that the respective axes r are inclined by an angle a comprised between 10° and 45° with respect to a horizontal plane; and

[0078] - the distance dmin between two adjacent bars 48 is defined by the respective edges 50 and is comprised between 0.2 mm and 2 mm.

[0079] As mentioned above, the plant 20 of the invention as a whole defines a material flow. In relation to the direction of such a material flow, for the apparatus 40 of the invention, the inlet end is understood to be unambiguously defined, meaning the portion of the apparatus 40 which receives the intermixed glass 30 and silicon 24 fragments arriving from the first machinery of the plant 20 itself. The apparatus 40 of the invention itself, with a single inlet, advantageously has two separate outlets, wherein a first outlet is intended for silicon fragments 24 and a second outlet is intended for glass fragments 30. Specifically, the inlet is placed higher than the two outlets, to facilitate the flow of glass 30 and silicon 24 fragments along the sieve 42 under the effect of gravity.

[0080] As already mentioned, in the present discussion the fragments derived from the photovoltaic cells are simply called silicon fragments 24, although they also comprise small amounts of silicon nitride, silver and / or aluminium.

[0081] As mentioned, the sieve 42 is configured to be vibrated during operation, again with the purpose of facilitating the movement of the glass 30 and silicon 24 fragments. For this purpose, in a manner known per se, the sieve 42 can, for example, be mounted on elastic suspension (not shown) and can comprise a motor (not shown) configured to rotate an eccentric mass at the desired frequency, e.g. at the resonance frequency of the mass of the sieve 42 suspended on its own elastic suspension. Thereby, by exploiting resonance, the energy absorbed by the motor can be minimised.

[0082] Notwithstanding the vibration imposed on the sieve 42, practical tests conducted by the Applicant have shown that it is highly preferable to adopt one or more solutions intended to facilitate the removal of glass 30 and / or silicon 24 fragments which can become trapped between two adjacent bars 48 during operation of the apparatus 40. Since obstruction of the slots 52 between the bars 48 compromises the effective separation of glass 30 and / or silicon 24 fragments, it is very important that they are kept clean.

[0083] For example, by modifying the intensity and frequency of the vibration over time, it is generally possible to remove the glass 30 and / or silicon 24 fragments which remain trapped in the slots 52 defined by each pair of adjacent bars 48.

[0084] In accordance with certain embodiments, the sieve 42 can assume a working configuration and a maintenance configuration. In the working configuration, the sieve assumes the characteristics described above, while in the maintenance configuration the distance dmax between two adjacent bars 48 is greater than dmin- Alternatively or additionally, the sieve 42 can comprise at least one blade 66 sliding between two bars 48 adjacent to each other. Preferably, the sieve 42 comprises a blade 66 sliding between each pair of bars 48. Both of these solutions, which will be described in more detail below, allow the removal of glass 30 and / or silicon 24 fragments which can be trapped between two adjacent bars 48.

[0085] By way of example, the sieve 42 can have a length (measured parallel to the axes r) comprised between 50 cm and 300 cm, preferably comprised between 100 cm and 200 cm. Furthermore, the sieve 42 can have a width comprised between 50 cm and 300 cm (measured transverse to the axes r), preferably around 150 cm. The axes r are inclined by an angle a comprised between 10° and 45°, preferably comprised between 20° and 30°, with respect to a horizontal plane (see Figures 1, 11 and 19).

[0086] In the present discussion, continuous reference is made to the axis r of each of the bars 48. The identification of an axis r is intuitive for the person skilled in the art, and a strict definition from a geometric point of view is not necessary. However, for the sake of completeness, it can be considered that in each bar 48, the axis r is the one passing through the centre of gravity of the cross section. The direction of the axis r is evidently the one of the main extension of the bar 48. As is known, the silicon 24 and glass 30 fragments which must be treated by the apparatus 40 of the invention are derived from photovoltaic panels and the related mechanical and heat treatments which are carried out upstream during the recycling operations. The silicon fragments 24 which reach the apparatus 40 of the invention are significantly smaller in thickness with respect to the glass fragments 30 with which they are mixed. In particular, the silicon fragments 24 have a thickness comprised between 150 jim and 300 pm, typically around 200 m. In contrast, the glass fragments 30 have a thickness comprised between about 3 mm and about 5 mm. For this reason, the minimum distance dmin between two adjacent bars 48 (see for example Figure 9) is comprised between 0.2 mm and 2 mm, preferably between 0.5 mm and 1.5 mm. In other words, when the sieve 42 is in working configuration, each pair of bars 48 adjacent to each other defines a narrow slot 52 parallel to the axis r and having width dmin.

[0087] Preferably, the bars 48, when edge 50 is juxtaposed against edge 50 in the working configuration, form a lead-in channel 54 which ends below in the slot 52 and has an opening angle [3 comprised between 40° and 120°. In other words, the side faces 56 of two adjacent bars 48 define a lead-in channel 54 which carries out a function similar to that of a linear funnel, conveying the fragments towards the slot 52 below.

[0088] As mentioned above, each bar 48 defines at least two edges 50, arranged on opposite sides with respect to the axis r. In particular, the two edges 50 extend linearly, parallel to each other and parallel to the axis r. Preferably, the cross section of each bar 48 defines at least two vertices 50' at the two edges 50. Preferably, the bars 48 of a single sieve 42 all have the same cross section. Preferably, each bar 48 has a constant cross section along its axis r.

[0089] Advantageously, the bars 48 are made of metal, preferably steel. Preferably, the edges 50 defined by each bar 48 are as sharp as possible and not rounded. For this purpose, it is preferable that the bars 48 are obtained from extruded profiles and not from folded sheets. Alternatively, or in addition, to sharpen the edges 50, the bars 48 can be subjected to special machining, such as flattening the side faces 56 defining the edges 50.

[0090] To improve the strength of the material of the bars 48 to the abrasive action of the glass fragments 30 flowing thereon, it is preferable that the outer surface of the bars 48, in particular near the edges 50, undergoes a surface hardening treatment. For example, if the bars 48 are made of steel, the outer surface can be advantageously treated by nitriding or carbo-cementation.

[0091] As mentioned above, in accordance with certain embodiments, the sieve 42 may assume a maintenance configuration, in which the bars 48 are moved away from each other, so that the distance dmax between two adjacent bars 48 becomes greater than dmin- Preferably dmaxis greater than twice dmin, even more preferably dmmis greater than five times dmin- Some possible technical solutions, which differ from each other, are described below, enabling the sieve 42 to pass from the working configuration to the maintenance configuration and vice versa.

[0092] In accordance with some embodiments, one or more of the bars 48 are configured to rotate around an axis parallel to its own axis r.

[0093] In accordance with some embodiments, the cross section of the bars 48 is a polygon, preferably a regular polygon.

[0094] By way of example, consider Figures 9 and 10 which schematically represent the cross section of a sieve 42 in the working configuration (Figure 9) and in the maintenance configuration (Figure 10), respectively. In this particular case, the cross section of the bars 48 is a square and thus defines four vertices 50', so that each bar 48 has four side faces 56 and four edges 50. This and other similar configurations imply some important advantages which are described below. By way of example, the side I of the square can be comprised between 3 cm and 10 cm, preferably between 4 cm and 6 cm. Based on what is mentioned above, in the working configuration, the minimum distance dmin between two adjacent bars 48 can be 1 mm, for example. In this particular case, to bring the sieve 42 into the maintenance configuration of Figure 10, each bar 48 is rotated by 45° around its own axis r. Thereby, if a side I of the bars 48 is considered, for example of 5 cm, the maximum distance dmax between two bars 48 comes to more than 2 cm.

[0095] It should be noted that, in order to be brought back from the maintenance configuration of Figure 10 to the working configuration of Figure 9, the square bars 48 can be rotated by 45° in the opposite direction to that of the previous rotation (thus bringing the bars 48 back to the exact same initial position) or the bars 48 can be rotated by 45° in the same direction as the previous rotation (thus bringing the bars 48 to a position which is rotated 90° from the initial position). It should be noted in this regard that each square bar 48 can indifferently assume as many as four positions around its axis r, in each of which it guarantees the operation of the sieve 42. In other words, if at each change of configuration all the bars 48 are rotated by 45° always in the same direction (e.g. always clockwise, in Figures 9 and 10), then each bar 48 successively uses all of its side faces 56 and all of its edges 50, thus distributing the wear due to the abrasive action of the glass fragments 30 flowing thereon.

[0096] In the example of Figures 9 and 10, the rotation axis of each bar 48 coincides with the axis r and both pass through the centre of gravity of the cross section. In other embodiments, the rotation axis of each bar 48 may not coincide with the axis r, thus determining a rototranslation motion of the cross section in the passage between the working configuration and the maintenance configuration.

[0097] Figures 9 and 10 show generic bars 48 with square section. Such bars 48, edge 50 juxtaposed against edge 50 in the working configuration, form a lead-in channel 54 which ends below in the slot 52 and has an opening angle [3 of 90°.

[0098] Figure 11 shows a solution in which the sieve 42 comprises a plurality of blades 66, each of which slides along the slot 52 comprised between two adjacent bars 48. In accordance with such an embodiment, in the sieve 42, the bars 48 are preferably fixed, i.e. they can assume the only configuration depicted in Figure 11. Of course, the fact that the bars 48 are fixed does not prevent them from vibrating. By numbering the positions of the bars 48 from 1 to n, the sieve 42 comprises n-1 blades 66. In Figure 12, the blades 66 are depicted in an intermediate point of their path as they slide parallel to the axes r with speed v. Preferably, the blades 66 can be brought to a rest position where they do not interfere with the operation of the sieve 42. The blades 66 comprise a front edge, intended to come into contact with the glass and silicon fragments which may be trapped between the bars. Preferably such a front edge is inclined with respect to the direction of the translation speed v of the blades 66 themselves.

[0099] Figures 12 to 14 show other possible technical solutions which allow to bring the sieve 42 from the working configuration to the maintenance configuration and vice versa. Each of such solutions has features which can make the use thereof advantageous under certain particular conditions. Of course, in the light of the present discussion, the person skilled in the art can identify other solutions, different from those shown, which can meet other specific needs. In Figures 11 to 14, the bars 48 of the sieve 42 are depicted for the sake of simplicity with a quadrangular cross section. Such a depiction must be understood by way of example and does not preclude that in such embodiments of the sieve 42, bars 48 can be used with different cross sections, some of which are described below by way of example.

[0100] Figure 12 shows a solution in which the bars 48 are configured to rotate, one every two, around an axis d perpendicular to the axes r. In other words, by numbering the positions of the bars 48 from 1 to n, by way of example the bars 48 occupying the odd- numbered positions are mounted in a fixed manner with respect to the structure of the sieve 42, while the bars 48 occupying the even-numbered positions are mounted so as to rotate about an axis d perpendicular to the axes r. In the embodiment of Figure 12, the axis d is placed near the upper end of the bars 48, but in other embodiments it can assume different positions, obtaining the same results. In the embodiment of Figure 12, the even- numbered bars 48 rotate integrally, but in other embodiments they can rotate independently of each other, obtaining the same results.

[0101] Figure 13 shows a solution in which the bars 48 are configured to translate, one every two, along a direction transverse to the axes r and having a vertical component. In other words, by numbering the positions of the bars 48 from 1 to n, by way of example the bars 48 occupying the odd-numbered positions are mounted in a fixed manner with respect to the structure of the sieve 42, while the bars 48 occupying the even-numbered positions are mounted so as to translate upwards. In the embodiment of Figure 13, the bars 48 translate upwards vertically, but in other embodiments they can translate upwards in different directions, obtaining the same results. In the embodiment of Figure 13, the even-numbered bars 48 translate integrally, but in other embodiments they can translate independently of each other, obtaining the same results.

[0102] Figure 14 shows a solution in which the bars 48 are configured to rotate, one every two, around an axis d parallel to and offset with respect to the axes r. In other words, by numbering the positions of the bars 48 from 1 to n, by way of example, the bars 48 occupying the odd-numbered positions are mounted in a fixed manner with respect to the structure of the sieve 42 while the bars 48 occupying the even-numbered positions are mounted so as to rotate about an axis d parallel to the axes r and placed near a side end of the sieve 42. In the embodiment of Figure 12, the even-numbered bars 48 rotate integrally, but in other embodiments they can rotate independently of each other, obtaining the same results.

[0103] Finally, in accordance with other possible embodiments (not shown), it is also possible to make the sieve pass from the working configuration to the maintenance configuration by rotating one bar 48 every two around its axis. In other words, by numbering the positions of the bars 48 from 1 to n, by way of example the bars 48 occupying the odd-numbered positions can be mounted in a fixed manner with respect to the structure of the sieve 42, while the bars 48 occupying the even-numbered positions can be mounted so as to rotate about their own axis r.

[0104] In addition to or as an alternative to the solutions described above, the removal of the glass 30 and / or silicon 24 fragments possibly sandwiched between two bars 48 can be facilitated by a special drive cycle, during which the vibration frequency of the sieve 42 is varied.

[0105] Figures 15 to 18 show some possible shapes that can be used for the cross sections of the bars 48. Once the shape of the cross section has been defined (e.g. square, as in Figure 15), the bars 48 can be either solid or tubular, depending on the specific needs. Each of the forms has features which can make the use thereof advantageous under certain particular conditions. Of course, in the light of the present discussion, the person skilled in the art can identify other cross sections, different from those shown, which can meet other specific needs.

[0106] As the person skilled in the art can well understand, each of the possible cross sections for the bars 48, for example those depicted in Figures 15 to 18, can belong to a sieve 42 configured in accordance with any one of the solutions described above, for example those described above with reference to Figure 11 comprising the blades 66, or with reference to Figures 12 to 14 configured to pass from the working configuration to the maintenance configuration and vice versa. Figure 15 shows tubular bars 48 with a square cross section. For such bars 48, everything which has been said above in relation to the square-section bars 48 in Figures 9 and 10 continues to apply. Furthermore, as the person skilled in the art can well understand, the tubular bars 48, i.e. internally hollow, simultaneously allow great stiffness (both flexural and torsional) while limiting mass and therefore weight and inertia.

[0107] Figure 16 shows bars 48 having a right-angled L cross section, i.e. in which the two wings of the L form an angle of 90°. The wings of the L define the side faces 56 of the bar 48 which, as in the square-section bars 48, form the lead-in channel 54 in which the glass 30 and silicon 24 fragments flow. The lead-in channel 54 ends below in the slot 52 and has an opening angle [3 of 90°. Furthermore, such L-shaped bars 48 allow to further limit mass and thus weight and inertia with respect to the tubular bars 48, e.g. those of Figure 15. Considering this, with respect to the tubular bars 48, the L-shaped bars lose stiffness, both flexural and torsional.

[0108] Even in the case where the bars 48 are each configured to rotate about its own axis parallel to or coincident with the axis r (analogous to what is described above for Figures 9 and 10), the bars of Figure 16 can each operate in one position only with respect to the rotation about the axis r. In other words, in the passage from the working configuration to the maintenance configuration and vice versa, the L-shaped bars 48 must be rotated by the same angle (45°) first in one direction (e.g. clockwise) and then in the opposite direction (e.g. counterclockwise). Thereby, the L-shaped bars 48 always expose the same side faces 56 and the same edges 50 to abrasion, wearing faster.

[0109] Figure 17 shows tubular bars 48 with an equilateral triangle cross section. Such bars 48, form a lead-in channel 54 which ends below in the slot 52 and has an opening angle [3 of 60°.

[0110] If the bars 48 are each configured to rotate around its own axis parallel to or coincident with the axis r (analogous to what is described above for Figures 9 and 10), the equilateral triangular bars 48 in Figure 17 can be rotated by 30°, e.g. clockwise. Conversely, in order to be returned from the maintenance configuration (not shown) to the working configuration of Figure 17, the equilateral triangular bars 48 can be rotated by 30° counterclockwise or they can be rotated by a further 90°, again clockwise. It should be noted in this regard that each bar 48 can indifferently assume three positions around its axis r, in each of which it ensures the operation of the sieve 42. In other words, similarly to what has been described above for the bars 48 with a square cross section, if at each change of configuration all the bars 48 are always rotated in the same direction (e.g. always clockwise), then each bar 48 successively uses all of its side faces 56 and all of its edges 50, thus distributing the wear due to the abrasive action of the glass fragments 30 flowing thereon. Furthermore, as mentioned above, the tubular bars 48 allow to obtain great stiffness (both flexural and torsional) while limiting mass and thus weight and inertia.

[0111] Figure 18 shows bars 48 having an obtuse L-shaped section, i.e. in which the two wings form an angle greater than 90°, in the example 100°. The side faces 56 of such bars 48 form a lead-in channel 54 which ends below in the slot 52 and has an opening angle [3 of 100°. These obtuse L-shaped bars 48 also make it possible to limit mass and thus weight and inertia with respect to the tubular bars 48, while however losing both flexural and torsional stiffness.

[0112] Moreover, like the bars 48 of Figure 16, they can each operate in a single position and wear out quickly.

[0113] In the embodiments of Figures 3 to 5, the sieve 42 is configured so that all the bars 48 rotate simultaneously, each around its own axis (typically around the axis r). As can be noted, this result is obtained by arranging a toothed wheel 58 at the end of each bar 48, which is fixed with respect to the bar 48 itself. The toothed wheel 58 of each bar 48 is configured to engage the toothed wheels 58 of the adjacent bars 48, so that the plurality of toothed wheels 58 together form what is called a "gear train". Thanks to this solution, it is possible to rotate all the bars 48 simultaneously by the same angle, each with respect to its own axis r. In other embodiments, the same result can be obtained in other manners, easily identifiable by the person skilled in the art. For example, instead of engaging the toothed wheels 58 to each other, it is possible to engage them to a common rack (not shown) whose translation determines the simultaneous and uniform rotation of all the bars 48.

[0114] Advantageously, as can be seen for example in Figures 2 to 6, inclined walls 60 are arranged around the sieve 42. Such inclined walls 60 are configured to convey any glass 30 or silicon 24 fragments which may accidentally fall sideways relative to the bars 48.

[0115] In accordance with some embodiments, the apparatus 40 further comprises a screen 62 placed upstream of the sieve 42 (see Figures 1 and 19). Such a screen 62 allows to remove fine particulate 64 from the mass of glass 30 and silicon 24 fragments, which, although of little commercial value, could cause problems for the operation of the apparatus 40 itself and contaminate the silicon 24 with unburned dust. Preferably, the screen 62 comprises an inclined plane on which is arranged a plurality of holes having a characteristic size equal to or greater than dmin- For example, the holes in the screen 62 can be round with a diameter comprised between 0.5 mm and 3 mm.

[0116] In accordance with some embodiments, the screen 62 and / or the sieve 42 comprise upper and / or lower closures configured to limit the dispersion of dust into the environment.

[0117] Preferably, first collecting means 44 are arranged below the sieve 42, configured to collect the silicon fragments 24 which fall along the slots 52 between one bar 48 and another. The first collecting means 44 can comprise a simple container placed directly below the sieve 42 (as diagrammed in Figures 1 and 19) or, alternatively, they can comprise a collector placed below the sieve 42 and configured to guide the silicon fragments 24 into a special container. The collector can for example take the form of a chute, a hopper, a conveyor belt or similar. Figures 2 to 6 show a chute collector below the sieve 42.

[0118] Preferably at the lower end of the sieve 42 (i.e. at the end opposite the inlet end), second collecting means 46 are arranged, configured to collect the glass fragments 30 which slide along the lead-in channels 54 between one bar 48 and the other. The second collecting means 46 can comprise a simple container placed directly downstream of the sieve 42 (as diagrammed in Figures 1 and 19) or, alternatively, they can comprise a collector or a conveyor belt (not shown) configured to guide the glass fragments 30 into a container away from the sieve 42.

[0119] In accordance with some embodiments, the apparatus 40 further comprises a second vibrating sieve 42.a, placed upstream of the first sieve 42. Thereby, the apparatus 40 is also configured for the separation of metal strips 26. The metal strips 26 are collected in third collecting means 68. The second sieve 42.a preferably incorporates all the technical features described above for the first sieve 42, with the sole exception of the distance dmin between two adjacent bars. In the second sieve 42.a, such a distance dmin is comprised between 1 mm and 2.5 mm. With the exception of the distance dmin between the bars 48, for a detailed description of the features of the second sieve 42. a, reference can be made to the description of the first sieve 42.

[0120] In accordance with some embodiments, for example those in Figures 19, 20 and 21, the second sieve 42.a is superimposed on the first sieve 42. As the person skilled in the art can well understand, this configuration allows to first separate the glass fragments 30, which have a thickness comprised between about 3 mm and about 5 mm, and which are conveyed by the second sieve 42.a into the special second collecting means 46. Conversely, thanks to the distance dmin separating the bars 48, the second sieve 42.a lets both the metal strips 26 and the silicon fragments 24 fall, which are then separated by the first sieve 42.

[0121] The operation of the apparatus 40 is briefly described below, although it is certainly clear to the person skilled in the art in the light of the present discussion.

[0122] The portion of the plant 20 upstream of the apparatus 40 is configured to treat the sandwich 22 derived from the photovoltaic panel deprived of its frame and junction box. In particular, the upstream plant 20 is configured to degrade and / or remove the PVF support panel 32, completely consume the EVA films 28 and possibly remove the metal strips 26 forming the electrical contacts. Ultimately, therefore, the apparatus 40 of the invention receives from the upstream plant 20 a mass of glass 30 and silicon 24 fragments, mixed together, which in some cases can also comprise metal strips 26. Such a mass is discharged at the inlet end of the sieve 42, near the upper end of the bars 48. Thanks to the acceleration of gravity g, the angle a of inclination of the bars 48 and the vibration of the sieve 42, the glass 30 and silicon 24 fragments begin to flow along the lead-in channels 54 defined by the side faces 56 of the bars 48. The silicon fragments 24 are thin enough (they have a thickness comprised between 150 pm and 300 pm, typically around 200 pm) to fall in the slot 52 defined by the edges 50 of two adjacent bars 48. The width of such a slot 52 is preferably comprised between 0.2 mm and 3 mm, even more preferably between 0.5 mm and 1.5 mm. The silicon fragments 24 thus fall in the first collecting means 44. In contrast, the glass fragments 30 are too thick to fall in the slots 52; in fact, they have a thickness comprised between about 3 mm and about 5 mm. The glass fragments 30 therefore slide along the entire length of the lead-in channels 54 defined by the side faces 56 of the bars 48, until they reach the lower end of the bars 48 and thus fall into the second collecting means 46.

[0123] As the person skilled in the art can well understand, the dimensions given above for the glass fragments 30 are of statistical value but, of course, it cannot be excluded that, mixed in with the others, there are smaller glass fragments 30 with respect to the dimensions considered. The possible presence of the screen 62 upstream of the apparatus 40 can greatly help eliminate fine glass fragments which could pass through the slots and contaminate the silicon fraction.

[0124] Furthermore, the glass fragments 30 can also have very irregular shapes and can have rough edges which wedge into the slot 52, trapping the fragment between two bars 48 along the lead-in channel 54. Even the silicon fragments 24, for example by assuming an anomalous orientation, can become trapped between the two bars 48, without being able to either slide along the lead-in channel 54 or fall in the slot 52. Of course, the presence of a single fragment, whether glass 30 or silicon 24, trapped along a lead-in channel 54, in turn determines the accumulation of other fragments, thus leading in short to a malfunctioning of the sieve 42. Correct vibration management helps to counteract the phenomenon, but the possibility of the slots 52 becoming clogged cannot be completely eliminated and becomes more and more likely as the operating time of apparatus 40 increases.

[0125] For this reason, it is preferable, at predefined intervals or when necessary, to temporarily suspend the operation of the apparatus 40, and move the sieve 42 from the working configuration to the maintenance configuration. By increasing the distance between the adjacent bars 48 (from dmin to dmax), any fragments trapped between two bars 48 are freed, falling below the sieve 42. Naturally, it is preferable that the first collecting means 44 are moved or reconfigured during these operations, so that the fragments which fall during the maintenance operations (which are a mixture of glass 30 and silicon 24) do not fall together with the fragments of only silicon 24 collected by the first collecting means 44 during the normal operation of apparatus 40. For example, if the first collecting means 44 comprise a chute collector, such as that of Figures 2 to 6, the collector itself can be rotated so that the fragments fall in a different direction from that along which the silicon fragments 24 fall during the normal operation of the apparatus 40. Again, if for example the first collecting means 44 comprise a conveyor belt, this can be set in motion in the opposite direction with respect to that of the normal operation of the apparatus 40.

[0126] In accordance with a second aspect, the invention relates to a plant 20 for recycling photovoltaic panels. The plant 20 of the invention (see Figures 1 and 19) is configured to treat a sandwich 22 comprising photovoltaic cells of silicon 24 and metal strips 26 embedded in a layer of EVA 28 enclosed between a front glass 30 and a back support panel 32 which can be made of glass or polymer material (typically PET and / or PVF).

[0127] The plant 20 comprises: a furnace 34 configured to completely consume the EVA 28 by means of combustion or pyrolysis; an apparatus 38 for separating the metal strips 26 from the flow of glass 30 and silicon 24 fragments; and an apparatus 40 for separating the glass fragments 30 and silicon fragments 24 in accordance with the above.

[0128] Preferably, the furnace 34 is of the type described in patent EP3993067B1.

[0129] In accordance with some embodiments (see Figure 1), the apparatus 38 for separating metal strips 26 is in accordance with what is described in the Italian patent application IT20240002932 entitled "IMPIANTO E METODO PER IL RICICLAGGIO DI PANNELLI FOTOVOLTAICI E APPARATO PER LA SEPARAZIONE DI BANDELLE METALLICHE" (i.e. "PLANT AND METHOD FOR RECYCLING PHOTOVOLTAIC PANELS AND APPARATUS FOR SEPARATING METAL STRIPS"), filed by the same Applicant on 12 February 2024.

[0130] In accordance with other embodiments (see Figure 19), the apparatus 38 for separating metal strips 26 is integrated in the apparatus 40, which comprises a second vibrating sieve 42. a, as described above.

[0131] Preferably, the plant 20 comprises third collecting means 68 for collecting the metal strips 26. In embodiments similar to that of Figure 19, the third collecting means 68 can also collect other fragments having grain size comprised between the dimensions of the slots 52 of the two superimposed sieves 42, 42.a.

[0132] The plant 20 can further comprise a fragmentation station 36 configured to fragment the front glass 30 and / or the back support panel 32 of the sandwich 22 and / or the silicon fragments 24. The fragmentation station 36 can be placed either upstream or downstream of the furnace 34. In accordance with some embodiments, the plant 20 comprises two fragmentation stations 36, one placed upstream of the furnace 34 and one placed downstream of the furnace 34.

[0133] The plant 20 can further comprise a screen 62 for removing fine particulate 64, consisting for example of fine glass fragments 30. The screen 62 for removing the fine glass fraction is preferably placed upstream of the apparatus 40. Preferably, the screen 62 comprises upper and lower closures configured to limit the dispersion of dust into the environment.

[0134] In accordance with a third aspect, the invention relates to a method for separating glass fragments 30 and silicon fragments 24 during the recycling of photovoltaic panels. The method of the invention comprises the steps of: arranging an apparatus 40 in accordance with the above; arranging a flow of glass fragments 30 and silicon fragments 24 mixed together; and separating the silicon fragments 24 from the glass fragments 30 by means of sieving.

[0135] As the person skilled in the art can well understand from the above description, the invention overcomes the drawbacks highlighted above in relation to the prior art.

[0136] In particular, the invention provides an apparatus 40, a plant 20 and a method for recycling photovoltaic panels with improved efficiency with respect to the known solutions.

[0137] Furthermore, the invention provides an apparatus 40, a plant 20 and a method for recycling photovoltaic panels, which allow the reliable and efficient separation of glass 30 from the silicon 24 of the photovoltaic panel.

[0138] Furthermore, the invention provides an apparatus 40, a plant 20 and a method for recycling photovoltaic panels, the construction and operation of which are simple and inexpensive.

[0139] Finally, the invention provides an apparatus 40, a plant 20 and a method for recycling photovoltaic panels which, in addition to the described advantages, allow the functionality of the known solutions to be maintained.

[0140] In conclusion, all the details can be replaced with other technically equivalent elements; the features described in connection with a specific embodiment can also be used in other embodiments; the materials used, as well as the contingent shapes and dimensions, can be any according to the specific implementation requirements without thereby falling outside the scope of protection of the following claims.

Claims

CLAIMS1. Apparatus (40) for separating glass fragments (30) and silicon fragments (24), comprising a vibrating sieve (42), first collecting means (44) and second collecting means (46), wherein:- the sieve (42) comprises a plurality of bars (48), each of which defines its own axis r;- the bars (48) have a cross section defining at least two edges (50) arranged on opposite sides with respect to the axis r;- the bars (48) are arranged so that the respective axes r are parallel to each other;- the bars (48) are arranged so that the respective axes r are inclined by an angle a comprised between 10° and 45° with respect to a horizontal plane; and- the distance dmin between two adjacent bars (48) is defined by the respective edges (50) and is comprised between 0.2 mm and 2 mm.

2. Apparatus (40) according to claim 1, wherein the sieve (42) can assume a working configuration and a maintenance configuration, and wherein, in the maintenance configuration, the distance dmax between two adjacent bars (48) is greater than dmin.

3. Apparatus (40) according to claim 1 or 2, wherein the bars (48) have a square cross section.

4. Apparatus (40) according to one or more of the preceding claims, wherein the bars (48) are tubular.

5. Apparatus (40) according to one or more of the preceding claims, wherein the cross section of the bars (48) has a side I comprised between 40 mm and 60 mm.

6. Apparatus (40) according to one or more of the preceding claims, wherein one or more bars (48) are configured to rotate about an axis parallel to its own axis r to facilitate the removal of glass fragments (30) and silicon fragments (24) trapped between the bars (48).

7. Apparatus (40) according to one or more of the preceding claims, further comprising at least one blade (66) sliding between two adjacent bars (48) to facilitate the removal of glass fragments (30) and silicon fragments (24) trapped between the bars (48).

8. Apparatus (40) according to one or more of the preceding claims, further comprising a second vibrating sieve (42.a), placed upstream of the first sieve (42), wherein:- the second sieve (42. a) comprises a plurality of bars (48) each of which defines its own axis r;- the bars (48) have a cross section defining at least two edges (50) arranged onopposite sides with respect to the axis r;- the bars (48) are arranged so that the respective axes r are parallel to each other;- the bars (48) are arranged so that the respective axes r are inclined by an angle a comprised between 10° and 45° with respect to a horizontal plane; and the distance dmin between two adjacent bars (48) is defined by the respective edges (50) and is comprised between 1 mm and 2.5 mm.

9. Plant (20) for recycling photovoltaic panels configured for treating a sandwich (22) comprising photovoltaic cells of silicon (24) and metal strips (26) embedded in an EVA layer (28) and enclosed between a front glass (30) and a back support panel (32) made of glass or polymer material, wherein the plant (20) comprises: a furnace (34) configured to completely consume the EVA (28) by means of combustion or pyrolysis;- an apparatus (38) for separating the metal strips (26) from the flow of glass (30) and silicon (24) fragments; and an apparatus (40) for separating the glass fragments (30) and silicon fragments (24) according to one or more of claims 1 to 7.

10. Plant (20) for recycling photovoltaic panels configured for treating a sandwich (22) comprising photovoltaic cells of silicon (24) and metal strips (26) embedded in an EVA layer (28) and enclosed between a front glass (30) and a back support panel (32) made of glass or polymer material, wherein the plant (20) comprises: a furnace (34) configured to completely consume the EVA (28) by means of combustion or pyrolysis;- an apparatus (40) for separating the metal strips (26), glass fragments (30) and silicon fragments (24) according to claim 8.

11. Plant (40) according to claim 9 or 10, comprising a fragmentation station (36) configured to fragment the front glass (30) and / or the back support panel (32) of the sandwich (22).

12. Plant (40) according to one or more of claims 9 to 11, further comprising a screen (62) for removing fine particulate (64), preferably placed upstream of the sieve (42).

13. Method for separating glass fragments (30) and silicon fragments (24) during the recycling of photovoltaic panels, comprising the steps of: arranging an apparatus (40) according to one or more of claims 1 to 8; arranging a flow of glass fragments (30) and silicon fragments (24) mixed together; andseparating the silicon fragments (24) from the glass fragments (30) by means of sieving.

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