Method and plant for separating an infill for artificial grass surfaces

Abstract

Method for separating an infill for artificial grass surfaces, the method comprising separating (830) artificial grass filaments from the infill, wherein separating said filaments comprises: - charging electrostatically capture elements (20); - investing said capture elements (20) with a flow of said infill to make said artificial grass filaments (3) to adhere at least partially to said capture elements (20); - removing said artificial grass filaments (3) from said capture elements (20).

Description

[0001] DESCRIPTION

[0002] Title: METHOD AND PLANT FOR SEPARATING AN INFILL FOR ARTIFICIAL GRASS SURFACES

[0003] Technical field of the invention

[0004] The present invention concerns a method and a plant for separating an infill for artificial glass surfaces.

[0005] State of the art

[0006] Artificial grass surfaces are known, for example for sports use (e.g. football fields, baseball fields, etc.), comprising an artificial turf mat comprising a support layer from which artificial filaments protrude which simulate natural grass. Typically, a layer of granular material, called infill, is spread between the artificial filaments. The infill improves the aesthetic quality of the artificial grass surface, making it more similar to natural grass (as it facilitates the upright maintenance of the artificial filaments), and / or improves its performance properties for sports use (for example in terms of mechanical response of the surface).

[0007] With wear, the artificial turf mat deteriorates and must be removed.

[0008] In this case, it is advantageous separating the infill present in the turf into its different constituent materials, in order to allow a recycling of the raw materials of which the infill is made.

[0009] Patent IT202000004087A1 describes a method and plant for the recycling of synthetic turf infill.

[0010] Summary of the invention

[0011] By infill it is generally meant, and where not otherwise specified, a mixture of different components in the constituent material / s deriving from an infill for artificial grass surfaces. The term infill may refer to such a mixture at any stage of the separation method of the present invention. Therefore, the same term "infill", depending on the context or phase of the method considered, can refer to mixtures that differ in terms of the presence and / or percentage content of the different components. For example, the term "infill" can comprise one or more infill fractions or one or more infill subtractions.

[0012] Typically, the infill comprises (in non-negligi ble content) at least two of, or all three, of the following components: a first granular material, a second granular material having specific density different from (e.g. lower than) the specific density of the first granular material, and artificial grass filaments.

[0013] The first granular material is for example made up of grains of sand or another material similar to sand in terms of particle size and specific density, e.g. another inert material or a totally vegetal material (e.g. dried fruit shells or fruit stones, e.g. olive stones).

[0014] The second granular material is for example made up of granules comprising a matrix of polymeric material and a filling filler, such as granules in an elastomeric blend coming from shredded tyres, granules in a polymeric material selected from the group: polyvinyl chloride (PVC), polyurethane (PU), polyester (PE), polypropylene (PP) filled with calcium carbonate and / or talc and / or cellulose and / or vegetal material, or granules in totally vegetal material (e.g. particles of cork, coconut, dried fruit shells, stones of fruit, etc), or their mixtures.

[0015] The artificial grass filaments are filaments which, following wear of the artificial grass surface, detach from the support layer and mix with the other components of the infill.

[0016] The expression "separating an infill", unless otherwise specified, means separating from the rest of the infill, at least partially, at least one component constituting the infill, with a higher degree of purity than that possessed by the component in the infill before separation. In other words, a selective separation of this component is expected. For example, the separated component can have a degree of purity greater than or equal to 70% by weight and / or volume, or greater than or equal to 90%.

[0017] The terms "upstream”, "downstream” and similar refer to the direction of flow of the infill during the separation.

[0018] The Applicant has faced the problem of separating an infill for artificial grass surfaces in an efficient manner, i.e. with a high degree of purity of at least one separated component, and / or with a reduced size of the separation plant, and / or with high separation capacity in terms of infill treated per unit of time.

[0019] According to the Applicant, the aforementioned problem is solved by a method and a plant in accordance with the attached claims and / or having one or more of the following features.

[0020] According to one aspect, the invention concerns a method for separating an infill for artificial grass surfaces.

[0021] Preferably the infill comprises filaments of artificial grass.

[0022] Preferably the method comprises separating said artificial grass filaments from the infill.

[0023] Preferably separating said filaments comprises electrostatically charging capture elements.

[0024] Preferably, separating said filaments of artificial grass comprises investing said capture elements with a flow of said infill to make said artificial grass filaments to adhere at least partially from said capture elements.

[0025] Preferably separating said filaments comprises removing said artificial grass filaments from said capture elements. According to one aspect, the invention concerns a plant for separating an infill for artificial grass surfaces.

[0026] Preferably the plant comprises one or more capture devices, each capture device comprising a main body defining a cavity and comprising an inlet and an outlet.

[0027] Preferably the plant comprises an infill movement system for generating a flow of said infill from said inlet to said outlet through said cavity.

[0028] Preferably each capture device comprises capture elements distributed inside said cavity.

[0029] Preferably each capture device comprises an electrical system for electrostatically charging said capture elements.

[0030] Preferably each catching device comprises a removal system for removing artificial grass filaments from said capture elements.

[0031] The Applicant has discovered that the capture elements distributed inside the cavity, when electrostatically charged (where the electric charges are typically distributed on the surface of the capture elements), favor the adhesion of the artificial grass filaments to the capture elements by electrostatic attraction thanks to the thread-like shape and polymeric material of the artificial grass filaments. Conversely, the rest of the infill (typically granules with a specific density greater than the filaments), due to its shape and / or material, does not remain adhered to the capture elements and continues its run. Therefore, the subsequent removal of the artificial grass filaments from the capture elements allows the recovery of the filaments, with a reduced or essentially zero content of the rest of the infill.

[0032] In this way, the separation of the artificial grass filament component from the rest of the infill is obtained with a high degree of purity.

[0033] The present invention, in one or more of its aspects, may comprise the following preferred features. Preferably one or more of the operations of the present method is performed in continuous.

[0034] Preferably said capture elements are made of electrically insulating material. In this way, the adhesion of the artificial grass filaments to the capture elements is promoted.

[0035] Preferably separating said artificial grass filaments comprises electrostatically discharging said capture elements (more preferably in a cyclic manner), wherein removing said artificial grass filaments from said capture elements takes place (preferably only) while said capture elements are electrically discharged.

[0036] Preferably, said electrical system is structured to electrostatically discharge said capture elements (cyclically).

[0037] Preferably the capture device comprises a control system. Preferably the control system is programmed for performing one or more of the operations of the method of the present invention.

[0038] Preferably the control system is programmed for commanding said electrical system to electrostatically charge and discharge said capture elements and for commanding said removal system to remove said artificial grass filaments from said capture elements (more preferably only) while said capture elements are electrically discharged.

[0039] In this way the removal of the grass filaments from the capture elements, which are no longer, or are weakly, attracted to the capture elements is facilitated.

[0040] Preferably, said removal of said filaments of artificial grass from said capture elements takes place by suction of said filaments.

[0041] Preferably said removal system comprises a suction system for sucking air from said cavity and the control system is programmed for commanding said suction system for sucking air from said cavity. In this way the artificial grass filaments are removed easily and / or efficiently.

[0042] Preferably separating said filaments of artificial grass comprises, following said suction of said filaments of artificial grass, electrostatically charging said capture elements again. In this way, the artificial grass filaments are separated from a further quantity of infill.

[0043] Preferably said main body has a main development direction which goes from the inlet to the outlet of the cavity. Preferably, said direction of development is inclined and descending from the inlet to the outlet (so that the infill chutes along the main body by gravity). Preferably said flow of the infill is parallel to said main development direction.

[0044] Preferably said capture elements are homogeneously distributed inside said cavity. In this way, the interaction between the infill and the capture elements is promoted.

[0045] Preferably said capture elements have a respective development direction (e.g. main) orthogonal to the main development direction of the main body, more preferably said respective development directions are all parallel to each other. Exemplarily said capture elements have a cylindrical shape, more preferably full, with axis along said main development direction.

[0046] Preferably each capture device comprises flow deflectors distributed (e.g. homogeneously) in the cavity. Preferably said flow deflectors have a plate-like shape, e.g. planar, more preferably with a development direction parallel to said respective development direction of said capture elements.

[0047] Preferably, said flow deflectors are shaped to create a tortuous path around the main development direction of the main body. In this way, turbulences are realized in the flow inside the cavity which allow the overall surface affected by the infill flow to be expanded and to promote the adhesion of the artificial grass filaments to said contact elements. Preferably said suction system is structured for sucking air from one side of said main body, more preferably along a direction parallel to said respective main development direction of the capture elements. Preferably the method comprises granulometrically screening (i.e. based on size) the infill to subdivide the infill into a plurality of infill fractions having different particle size, more preferably having respective particle size ranges contiguous to each other and non-overlapping.

[0048] Preferably the plant comprises a granulometrical screening device, for example a nutation sieve.

[0049] Preferably said granulometrically screening said infill is performed by a granulometrical screening device.

[0050] Preferably said granulometrical screening device comprises a plurality of filters each having a different particle size (i.e. the size of the respective openings), a feeding inlet, a waste outlet and a plurality of discharge outlets. Preferably said filters of said plurality of filters are arranged in an ordered sequence with decreasing particle size, more preferably vertically stacked.

[0051] Preferably said feeding inlet is located upstream (and more preferably above) a first filter of said plurality of filters. Preferably said waste outlet is located upstream of a first filter of said plurality of filters. Preferably each discharge outlet is located downstream of a respective filter of said plurality of filters.

[0052] Preferably a first filter of said plurality of filters has a particle size between 1500 m and 3500 pm.

[0053] Preferably a second filter of said plurality of filters has a particle size between 1000 pm and 2000 pm.

[0054] Preferably a third filter of said plurality of filters has a particle size between 600 pm and 1400 pm.

[0055] Preferably a fourth filter of said plurality of filters has a particle size between 500 pm and 800 pm.

[0056] Preferably a fifth filter of said plurality of filters has a particle size between 300 pm and 600 pm.

[0057] Preferably said plurality of infill fractions comprises a first and a second infill fraction, more preferably a third infill fraction, even more preferably a fourth infill fraction, even more preferably a fifth infill fraction, said infill fractions being arranged in decreasing particle size order. Preferably it is expected to discharge each infill fraction from the respective discharge outlet located downstream of the respective filter (for example the third infill fraction comes out from the third discharge outlet downstream of the third filter).

[0058] Preferably one infill fraction, more preferably the first infill fraction, substantially consists of said second granular material and possibly of said artificial grass filaments.

[0059] Preferably one or more other infill fractions, more preferably at least two other infill fractions, even more preferably the second, third and / or fourth infill fractions, each comprise said first and second granular material and possibly the artificial grass filaments.

[0060] Preferably a further infill fraction, more preferably the fifth (last) infill fraction, substantially consists of said first granular material and possibly in said artificial grass filaments.

[0061] In this way the infill is separated into its constituent components considering the granulometric differences of the components and with reduced overall dimensions of plant.

[0062] Preferably said separating of said artificial grass filaments is performed (separately) on one or more of said infill fractions, more preferably on at least two or three of said infill fractions, even more preferably on each infill fraction, following said granulometrically screening.

[0063] Preferably said one or more capture devices are arranged downstream of said granulometrical screening device.

[0064] Preferably the plant comprises a plurality of said capture devices, said plurality of capture devices comprising a first and a second capture device, more preferably a third capture device, even more preferably a fourth capture device, even more preferably a fifth capture device. Preferably each capture device (e.g. the respective inlet) is arranged directly downstream of a respective discharge outlet of said plurality of discharge outlets of the granulometrical screening device.

[0065] In this way the respective infill fraction is cleaned at least in part of the artificial grass filaments. The Applicant has discovered that the separation of the artificial grass filaments downstream of the granulometrical screening is particularly effective.

[0066] Preferably the method comprises densimetrically separating (i.e. based on the specific density of the constituents of the infill) the infill, more preferably one or more infill fractions, even more preferably at least two or three infill fractions, even more preferably called second, third and fourth infill fraction, into a respective first infill sub-fraction and a respective second infill sub-fraction having different density (e.g. lower) than said respective first infill sub-fraction.

[0067] Preferably the plant comprises one or more densimetric separation devices. Exemplarily, each densimetric separation device is an air flow volumetric separator comprising a vibrating densimetric table.

[0068] Preferably said densimetrically separating is performed by one or more densimetric separation devices.

[0069] Preferably densimetrically separating is preferably performed after said separating of said artificial grass filaments and / or after said granulometrically screening.

[0070] Preferably each densimetric separation device comprises a first and a second opening outlet, wherein each densimetric separation device is configured for conveying a first sub-fraction of infill towards said first opening outlet and towards said second opening outlet a second infill sub-fraction having different density (e.g. lower) than said first infill subtraction.

[0071] Preferably each first infill sub-fraction substantially consists of said first granular material.

[0072] Preferably each second infill sub-fraction substantially consists of said second granular material and said artificial grass filaments.

[0073] In this way, the infill is further separated into its constituent components by considering the densimetric differences of the constituents and the filament separation method is more effective.

[0074] Preferably the plant comprises a plurality of said densimetric separation devices, said plurality of densimetric separation devices comprising a first densimetric separation device arranged directly downstream of said second capture device, a second densimetric separation device arranged directly downstream of said third capture device, and more preferably a third densimetric separation device arranged directly downstream of said fourth capture device.

[0075] Preferably each densimetric separation device is arranged directly downstream of a respective outlet of a respective capture device.

[0076] The Applicant has discovered that densimetrically separating at least two, more preferably at least three, infill fractions, each having a reduced particle size range (in particular in the lower part of the grain size scale), a high densimetric separation efficiency is obtained.

[0077] Preferably the method comprises a further separation operation of said artificial grass filaments from the infill, more preferably from one or more of said infill fractions (e.g. said first infill fraction) and / or from one or more of said second infill sub-fractions, even more preferably from each second infill sub-fraction.

[0078] Preferably said further operation of separation separates said artificial grass filaments from said second granular material.

[0079] Preferably said further separation operation comprises investing said infill in a free fall with a flow of air (more preferably constant).

[0080] Preferably the plant comprises one or more air flow separation devices, each device being for example a "leap” stream separator.

[0081] Preferably, said further separation operation of said artificial grass filaments is performed by one or more air flow separation devices.

[0082] Preferably each air flow separation device comprises a hopper, a separation chamber, a fan for generating said air flow in said separation chamber, a first outlet proximal to said fan (for collecting the second granular material) and a second outlet distal to said fan (for collecting the lighter artificial grass filaments).

[0083] Preferably the plant comprises a plurality of said air flow separation devices.

[0084] Preferably one of said air flow separation devices is arranged directly downstream of one of said capture devices. Preferably one or more other devices of said air flow separation devices are arranged directly downstream of a respective densimetric separation device.

[0085] Preferably said plurality of airflow separation devices comprising a first airflow separation device disposed directly downstream of said first capture device, a second airflow separation device disposed directly downstream of said first densimetric separation device, more preferably a third air flow separation device disposed directly downstream of said second densimetric separation device, and even more preferably a fourth air flow separation device disposed directly downstream of said third densimetric separation device.

[0086] In this way it is possible to obtain (in particular in combination with the aforementioned previous operation of separating the filaments of artificial grass through electrostatic adhesion) an almost total separation of the filaments from the rest of the infill, to the advantage of the purity of the second granular material finally separated.

[0087] The Applicant has discovered that the combination of the densimetric separation and the subsequent further filament separation operation synergistically realizes an efficient filament separation. The Applicant considers, without wanting to restrict itself to any theory, that the filaments, being light, in the densimetric separation naturally tend to follow the second granular material. Therefore, the second infill sub-fractions contain substantially all the filaments and consequently it is not necessary to perform the further operation of separating the filaments from the first infill subtractions), or even from the fifth fraction. The subsequent further separation of the filaments through air flow exploits the difference in shape between the filaments and the second granular material. This combination therefore constitutes an aspect of the present invention in its own right, regardless of whether or not the aforementioned densimetric separation operation is performed using the electrostatically charged elements.

[0088] The Applicant has also discovered that the combination of the separation of the filaments through the electrostatically charged capture elements, the subsequent densimetric separation and the subsequent further filament separation operation synergistically achieves an efficient separation of the filaments. The Applicant considers, without wanting to restrict itself to any theory, that contact with the capture elements can electrostatically charge the second granular material (typically dielectric) and / or the filaments that are not captured, thus favoring their adhesion during the densimetric separation. Therefore, the second infill sub-fractions contain substantially all filaments that are not captured in the (first) filament separation operation (and consequently it is not necessary to perform the further filament separation operation from the first filament separation operation(s) below - fraction(s) of infill, and not even from the fifth fraction).

[0089] Preferably the movement system of the infill comprises a plurality of mechanical movement devices distributed along a path to generate a flow of infill along said path, more preferably substantially continuous. Preferably said mechanical movement devices are active (i.e. motorized) and / or passive (i.e. non-motorized). Preferably said active mechanical movement devices are chosen from the group: elevators, e.g. bukett elevators, screw conveyors and belt conveyors. Preferably said passive mechanical handling devices are chutes (e.g. said main body of the capture device).

[0090] Preferably the method comprises drying the infill prior to said separating said artificial grass filaments from the infill and / or said granulometrically screening and / or said densimetrically separating and / or said further operation of separating said artificial grass filaments.

[0091] Preferably the plant comprises a dryer arranged upstream of said one or more capture devices, and / or of said granulometrical screening device, and / or of said one or more densimetric separation devices and / or of said one or more air flow separation devices.

[0092] Preferably the dryer is a rotary dryer.

[0093] In this way the infill is more easily treatable, e.g. as its components result mutually freer.

[0094] Preferably the method comprises, during said drying the infill, sucking powders and / or artificial grass filaments from said infill.

[0095] Preferably the plant comprises a suction and filtering device structured for sucking air from said dryer and for filtering said sucked air to separate powder and / or artificial grass filaments.

[0096] In this way the infill is cleaned of powders and / or filaments, for the purposes of a greater subsequent separation efficiency.

[0097] Preferably the method comprises mixing said infill prior to said drying.

[0098] Preferably the plant comprises a buffer tank upstream of said dryer. Preferably said buffer tank comprises an element for mixing said infill.

[0099] In this way the infill is made uniform over time, for example by mixing infills from different fields, in order to keep the properties of the infill to be separated constant over time.

[0100] Preferably the method comprises removing said infill from an artificial turf mat prior to said mixing the infill and / or said drying the infill and / or said separating said artificial grass filaments from the infill and / or said granulometrically screening and / or of said densimetrically separating and / or of said further separation operation of said artificial grass filaments.

[0101] Preferably the plant comprises a device for removing the infill from an artificial turf mat, upstream of said buffer tank and / or of said dryer, and / or of said one or more capture devices, and / or of said device of granulometrically screening, and / or of said one or more densimetric separation devices and / or of said one or more air flow separation devices.

[0102] In this way, the infill is removed from artificial grass carpets and subsequently separated into its constituent components.

[0103] Brief description of the figures figure 1 schematically shows a plan view of a plant according to the present invention; figures 2 and 3 show two respective portions of figure 1 ; figure 4 schematically shows a perspective view, partial and partially exploded, of the capture device according to the present invention; figure 5 schematically shows a side view of a granulmetrical screening device; figure 6 schematically shows a side view of a densimetric separation device; figure 7 schematically shows a side view of an air flow separation device, with some parts in transparency; figure 8 shows an exemplary flow diagram of the separation method of the present invention.

[0104] Detailed description of some embodiments of the invention

[0105] The features and advantages of the present invention will be further clarified by the following detailed description of some embodiments, presented by way of example and not as a limitation of the present invention, with reference to the attached figures.

[0106] In figure 1 , with the number 99 it is indicated a plant for separating an infill for artificial grass surfaces according to the present invention. More specifically, the plant 99 is configured for separating the infill into the different components of which it is composed with a desired degree of purity.

[0107] Exemplarily the infill comprises a first granular material consisting of sand granules, having for example a particle size of between approximately 100 m and 1400 pm.

[0108] Exemplarily the infill includes a second granular material 2 made up of SBR rubber granules, possibly recycled (for shredding used tyres). Exemplarily the second granular material 2 has a particle size between 800 pm and 2500 pm. Exemplarily the infill can also comprise powder, i.e. granular material with particle size lower than the one of sand, for example less than 50 pm, and / or small stones or other foreign objects, generally having dimensions greater than 3000 pm.

[0109] Exemplarily the infill also comprises artificial grass filaments 3, for example made of polypropylene (PP) and / or polyethylene (PE). Exemplarily the artificial filament has a mass per unit length of approximately 2000 dtex.

[0110] It is observed that the plant of the present invention could also be used for the separation of other mixtures of granular material in which there is an overlap of particle size ranges of granules of different materials, such as for example the recovery and recycling of riding sands, the drying and selection of silica sand for construction, processing of inert materials such as kaolin and feldspathic material for the production of ceramic tiles, selection and separation of spherical quartz and mill for the production of pharmaceutical glass.

[0111] Exemplarily the plant 99 comprises a removal device 150 for removing the infill from an artificial turf mat. The removal device 150 is not further described and illustrated, as for example it is of the type described in the aforementioned patent IT202000004087A1.

[0112] Alternatively, the plant 99 could not comprise the removal device 150 and be configured for processing the infill already removed from the respective artificial turf mat. However, its presence is preferable in order to perform all the separation operations within the same plant.

[0113] The plant 99 comprises a movement system 75 of the infill for generating a substantially continuous flow of the infill along a path. Exemplarily the movement system of the infill comprises a plurality of handling devices distributed along the path, comprising for example a plurality of bucket elevators 70 and screw conveyors (or augers) 72, and a plurality of chutes 73, inclined at least 35° with respect to the horizontal (the chutes operating in combination with the elevators). Downstream of the removal device 150, exemplarily the plant 99 comprises a buffer tank 200. Exemplarily the buffer tank 200 comprises an element (not shown) for mixing the infill.

[0114] Downstream of the buffer tank 200, the plant 99 exemplarily comprises a dryer 300. Exemplarily the dryer 300 is a rotary dryer comprising a drying chamber, a rotary system (e.g. rotating cylinder equipped with blades on the inner surface) and an introduction of hot gas. The rotary system transposes the infill into an upper portion of the drying chamber, where the hot gas generated by the inlet system hits the infill.

[0115] Alternatively, the dryer can be a fluid bed type dryer.

[0116] Preferably the dryer 300 comprises a first outlet crossed by the dried infill and a second outlet in communication (e.g., by a suction duct 74) with a suction and filtering device 310 structured to suck air from the dryer 300 and to filter the air sucked for separate powders and / or artificial grass filaments. Exemplarily the suction and filtering device 310 is a bag house filter, e.g. of the piston type, comprising a suction fan and a fabric filtering unit positioned between the second outlet of the dryer 300 and the suction fan and comprising one or more filter media shaped so as to retain artificial grass filaments and powder 301 which are conveyed by a screw 72 and collected in a container (not shown) by an elevator 70.

[0117] Exemplary the plant 99 comprises a granuometrical screening device 400 arranged downstream of the dryer 300. Exemplary the granulometrical screening device 400 is a nutation sieve.

[0118] Exemplarily, the granulometrical screening device 400 (fig. 5) comprises a feeding inlet 11 (connected by chute 73 and elevator 70 to the first outlet of the dryer 300), a plurality of filters 6-10 each having a different particle size, a waste outlet 12 and a plurality of waste outlets 13-17. The granulometrical screening device 400 exemplary comprises a boxshaped casing, wherein the feeding inlet 11 is made in a top portion of the box-shaped casing.

[0119] Exemplarily the filters are vertically stacked in an ordered sequence with decreasing particle size from top to bottom, where the first filter 6 (exemplarily having openings with a particle size of approximately 2500 pm) is arranged in the top position, and is followed, from top to bottom , from a second filter 7 (exemplarily having openings with a particle size of approximately 1400 pm), a third filter 8 (exemplarily having openings with a particle size of approximately 800 pm), a fourth filter 9 (exemplarily having openings with a particle size of approximately 600 pm) and a fifth filter 10 (exemplarily having openings with a particle size of approximately 400 pm). The waste outlet 12 is made in a lateral portion of the box-shaped casing and is placed at a vertical height just higher than the vertical height of the first filter 6. The granulometrical screening device 400 comprises, from top to bottom, a first outlet discharge outlet 13, a second discharge outlet 14, a third discharge outlet 15, a fourth discharge outlet 16 and a fifth discharge outlet 17, respectively placed at a vertical height just lower than the vertical height of the first 6, second 7, third 8, fourth 9 and fifth filter 10 (each discharge outlet, except for the fifth, being placed between two respective consecutive filters).

[0120] In one alternative embodiment (not shown), the granulometrical screening device comprises a closed body inside which there are tubular filters or a plurality of linear filters inclined with respect to a horizontal plane (and also with respect to a vertical plane).

[0121] Preferably the plant 99 comprises a first 505, a second 510, a third 515, a fourth 520 and a fifth 525 capture device. Exemplarily (fig. 4), each capture device comprises a main body 21 defining a cavity 22 and comprising an inlet 23 and an outlet 24.

[0122] Exemplarily the main body 21 has a main development direction 100 that goes from the inlet 23 to the outlet 24 of the cavity 22. Exemplarily the flow of the infill is generally parallel to the main development direction 100. Exemplarily the development direction has inclination greater than 35° with respect to a horizontal reference plane. In particular, the inlet 23 of the main body 21 is located at a vertically higher level than the outlet 24 of the main body 21. In this way, the main body also acts as a chute for the flow of infill.

[0123] Exemplarily each capture device comprises capture elements 20 made of electrically insulating material and homogeneously distributed inside the cavity 22. Exemplarily the capture elements 20 have a respective main development direction perpendicular to the main development direction 100 of the main body 21 , where the respective directions of development are all parallel to each other. Exemplarily the capture elements 20 have a solid cylindrical shape, with an axis along the main development direction 100. For example, each capture element 20 comprises a cylindrical core made of ceramic material coated with a thermoplastic polymeric material (e.g. Teflon).

[0124] Exemplarily each capture device comprises flow deflectors 30 distributed (e.g. homogeneously) in the cavity 22. Exemplarily, the flow deflectors 30 have a planar plate-like shape with a direction of development parallel to the respective direction of development of the capture elements 20. Exemplarily, the flow deflectors flow 30 are shaped and oriented in order to realize a path for the infill flow with a tortuous pattern around the main development direction 100 of the main body 21.

[0125] Exemplarily, each capture device comprises an electrical system (possibly shared among all the capture devices, or a respective electrical system dedicated to each capture device), not shown as it is for example of a known type, for electrostatically charging and discharging the recording elements capture 20.

[0126] Exemplarily, each capture device comprises a removal system (not shown, shared or dedicated to each capture device) for removing the artificial grass filaments from the capture elements 20. Exemplarily, the removal system comprises a suction system (not shown) to suck air from the cavity 22, for example through a plurality of openings 40 obtained on one side of the main body 21 , along a direction parallel to the respective main development direction of the capture elements 20, and a respective outlet (not shown) structured for transporting the aspirated artificial grass filaments outside of each capture device.

[0127] Exemplarily, each capture device comprises (shared or dedicated to each capture device) a control system (not shown) programmed for controlling the electrical system for electrostatically charging and discharging the capture elements 20 and controlling the removal system to suck air from the cavity 22.

[0128] The respective inlet 23 of the first capture device 505 is directly in flow communication with the first discharge outlet 13. The respective inlet 23 of the second capture device 510 is directly in flow communication with the second discharge outlet 14. The respective inlet 23 of the third capture device 515 is directly in flow communication with the third discharge outlet 15. The respective inlet 23 of the fourth capture device 520 is directly in flow communication with the fourth discharge outlet 16. The respective inlet 23 of the fifth capture device 525 is directly in flow communication with the fifth discharge outlet 17, and the respective outlet 24 of the fifth capture device 525 is directly in flow communication with a screw 72 for the first granular material (visible in fig. 2). Exemplarily, the plant 99 comprises a first 605, a second 610 and a third 615 densimetric separation device.

[0129] Exemplarily, each densimetric separation device (fig. 6) comprises a vibrating densimetric table 1 , having a respective inlet 19 and a first 31 and a second outlet 32. Exemplarily, the vibrating densimetric table 1 is inclined (by a value between 9° and 13°) with respect to a horizontal plane and is equipped with through openings (with a diameter between 200 m and 400 pm), from which a flow of gas (with a direction going from bottom to top) placed under pressure by a pumping unit, and a vibrating unit, to set the table 1 into vibration. In general, the second outlet 32 is placed at a higher level than at the first exit 31.

[0130] Exemplarily, the respective first outlet 31 of the first 605, second 610 and third 615 densimetric separation device is in direct flow communication with the screw 72 for the first granular material (fig. 2).

[0131] Exemplarily, the respective output 24 of the second 510, third 515 and fourth capture device 520 is in direct flow communication with the respective input 19 of the first 605, second 610 and third 615 densimetric separation device, respectively.

[0132] Exemplary, the plant 99 comprises a first 705, second 710, third 715 and fourth 720 air flow separation device, for example a "leap" stream separation device.

[0133] Exemplary, each air flow separation device comprises (fig. 7) a hopper 711 , a separation chamber 713, a respective fan 712 for generating the air flow in the separation chamber, a first outlet 701 proximal to the fan 712 and a second outlet 702 distal from the fan.

[0134] Exemplarily, the first air flow separation device 705 is arranged directly downstream of the first capture device 505, the second air flow separation device 710 is arranged directly downstream of the first densimetric separation device 605, the third airflow separation device 715 is disposed directly downstream of the second densimetric separation device 610 and the fourth airflow separation device 720 is disposed directly downstream of the third densimetric separation device 615.

[0135] Exemplarily, the plant 99 comprises a screw 72 for the second granular material in direct flow communication with the respective first outlet 701 of the first 705, second 710, third 715 and fourth 720 air flow separation device.

[0136] Exemplarily, the plant 99 comprises a screw 72 for the filaments 3 in direct flow communication with the respective second outlet 702 of the first 705, second 710, third 715 and fourth 720 air flow separation device.

[0137] Exemplarily, each screw has a respective outlet for the ejection of the respective material into a respective container (not shown), by a respective elevator 70.

[0138] In use, the plant 99 allows to perform a method for separating the artificial grass filaments from the infill according to the present invention, described below with reference to fig. 8.

[0139] Exemplarily, the method initially comprises, using the removal device 150, removing the infill 190 from the artificial tuft mat. For example, the infill 190 is then transported, by the chute 73 and the bucket elevator 70, to the buffer tank 200, wherein it is provided mixing 800 the infill.

[0140] Exemplarily, the method comprises, after having uniformed the infill in the buffer tank 200 and transported the infill to the dryer 300 by the chute 73 and the bucket elevator 70, drying the infill 810 in the dryer 300. For example, the drying takes place at a temperature between 90°C and 150°C.

[0141] During the drying of the infill, the method exemplarily comprises sucking powders and / or filaments of artificial grass from the infill by the suction and filtering device 310 which sucks air from the dryer 300 through the second outlet of the dryer 300 and expels the artificial grass filaments and / or powder 301, subsequently transported, by the screw 72, into a container to be discarded.

[0142] Exemplarily, it is expected to transport the dried infill 191, through the second outlet of the dryer 300, up to the granulometrical screening device 400 by the chute 73 and the bucket elevator 70.

[0143] Exemplarily, the method comprises, by means of the granulometrical screening device 400, granulometrically screening 820 the dried infill 191 for dividing the infill into a plurality of infill fractions with different particle sizes having respective particle size ranges which are contiguous and not overlapping.

[0144] Exemplary, the infill is divided into a discharge fraction and five infill fractions.

[0145] Crossed the supply inlet 11, the infill hits in exemplary sequence a first 6, a second 7, a third 8, a fourth 9 and a fifth filter 10. The infill fraction that does not pass through the through openings of the first filter 6, comes out from the discharge outlet 12. This infill fraction corresponds to the discharge fraction 401 mainly comprising small stones or other foreign objects. The infill fraction that does not pass through the through openings of the second 7, third 8, fourth 9 and fifth filter 10, comes out respectively from the first 13, second 14, third 15 and fourth exhaust outlet 16. These infill fractions correspond respectively to the first, second, third and fourth infill fraction. The infill that has passed through the fifth filter 10 comes out from the fifth discharge outlet 17 and corresponds to the fifth infill fraction.

[0146] Exemplarily, the first infill fraction essentially consists of the second granular material 2 and possibly the artificial grass filaments 3 (i.e. the content of the first granular material is negligible).

[0147] Exemplarily, the second, third and / or fourth infill fractions each comprise the first and second 2 granular material and possibly the artificial grass filaments 3.

[0148] Exemplarily, the fifth infill fraction essentially consists of the first granular material and possibly the artificial grass filaments 3 (i.e. the content of the second granular material is negligible).

[0149] Exemplarily, it is expected to send each fraction of infill from the granulometrical screening device 400 directly to the respective capture device.

[0150] Preferably the method comprises separating 830 the filaments of artificial grass 3 from the infill, using each capture device, in particular from each of the five infill fractions.

[0151] Exemplarily separation 830 of the artificial grass filaments comprises electrostatically charging the capture elements 20 and investing the capture elements 20 with a flow of each infill fraction, to make the artificial grass filaments 3 adhere at least partially to the capture elements 20.

[0152] Exemplarily separating the filaments of artificial grass 830 comprises, cyclically (e.g. every 10 s of flow with charged elements), electrostatically discharging the capture elements 20, for example for a fraction of a second and simultaneously removing the artificial grass filaments 3 from the elements of capture 20, exemplarily by suction of air from cavity 22.

[0153] Subsequently, the capture elements 20 are loaded again for a subsequent cycle.

[0154] Exemplarily, the aforementioned operations are controlled by the control system suitably configured by an operator, the control system controlling the electrical system and the removal system.

[0155] Exemplarily, the first, second, third, fourth and fifth infill fraction come out from the first 505, second 510, third 515, fourth 520 and fifth 525 capture device through the respective outlet 24.

[0156] Exemplarily, the method comprises densimetrically separating 840, using each densimetric separation device, the second, third and fourth fractions of the infill into respective infill sub-fractions having different specific densities.

[0157] Exemplarily, each densimetric separation device conveys towards the first outlet 31 a respective first infill sub-fraction 601 having a density greater than a predetermined threshold value and towards the second outlet 32 a respective second infill sub-fraction 650, having a density lower than the first sub-fraction.

[0158] Exemplarily, the first infill sub-fraction 601 essentially consists of the first granular material. Exemplarily, the first subtraction is conveyed into a container through the screw 72 of the first granular material and a respective elevator 70. Exemplarily, the second infill sub-fraction 650 substantially consists of the second granular material 2 and the artificial grass filaments 3. Exemplarily, each second infill sub-fraction 650 is transported to the respective air flow separation device by the elevator 70 and the chute 73.

[0159] Exemplarily, the method comprises a further separation operation 850 of the artificial grass filaments from the infill, in particular from each second infill sub-fraction 650. Exemplarily, the first infill fraction 651 coming out of the previous filament separation operation is not subjected to densimetric separation, but is directly subjected to the further separation operation 850.

[0160] Exemplarily, the further separation operation 850 separates the residual artificial grass filaments 3 from the second granular material 2.

[0161] Exemplarily, the further separation operation 850 comprises hitting the free-falling infill with a flow of air (e.g. constant), so that, thanks to the difference in shape and / or specific density, the second granular material 2 is collected in the first outlet 701 proximal to the fan 712 and subsequently transported, by the respective screw 72 and an elevator 70, to a container, and the artificial grass filaments 3 are collected in the second outlet 702 distal to the fan 712 and subsequently transported, by the further screw 72 and an elevator 70, to a container.

Claims

CLAIMS1. Method for separating an infill for artificial grass surfaces, the method comprising separating (830) artificial grass filaments from the infill, wherein separating said filaments comprises:- charging electrostatically capture elements (20);- investing said capture elements (20) with a flow of said infill to make said artificial grass filaments (3) to adhere at least partially to said capture elements (20);- removing said artificial grass filaments (3) from said capture elements (20).

2. Method according to claim 1, wherein said capture elements (20) are made of electrically insulating material, wherein separating (830) said filaments (3) comprises electrostatically discharging said capture elements (20), and wherein said removing said artificial grass filaments (3) from said capture elements (20) takes place through suction of said filaments (3) while said capture elements (20) are electrically discharged.

3. Method according to any one of the previous claims, wherein the infill comprises a first granular material and a second granular material (2) having specific density lower than the specific density of the first granular material, wherein the method further comprises granulometrically screening (820) the infill to subdivide the infill into a plurality of infill fractions having respective particle size ranges contiguous to each other and not overlapping, wherein said plurality of infill fractions comprises at least four infill fractions ordered in decreasing particle size order, wherein one of said infill fractions substantially consists of said second granular material (2) and of said artificial grass filaments (3), wherein at least two other infill fractions of said infill fractions each comprise said first and second (2) granular material and the artificial grass filaments (3) and wherein at least one further infill fraction of said infill fractions consists substantially of said first granular material and said artificial grass filaments (3), and wherein said separating (830) said artificial grass filaments (3) is performed on one or more of said infill fractions.

4. Method according to claim 3, further comprising, subsequent to said separating (830) said artificial grass filaments (3):- densimetrically separating (840) one or more infill fractions into a respective first infill sub-fraction (601) and a respective second infill sub-fraction (650) having a density lower than said respective first infill sub-fraction (601), wherein each first infill sub-fraction (601) substantially consists of said first granular material and each second infill sub-fraction (650) substantially consists of said second granular material (2) and said artificial grass filaments (3).

5. Method according to claim 4, further comprising:- a further separation operation (850) of said artificial grass filaments (3) from one or more of said infill fractions and / or from one or more of said second infill sub-fractions (650), wherein said further operation of separation (850) separates said artificial grass filaments (3) from said second granular material (2), wherein said further separation operation (850) comprises investing said infill in free fall with a flow of air.

6. Method according to any one of the previous claims, further comprising, prior to said separating (830) said artificial grass filaments from the infill and said granulometrically screening (820):- mixing (800) said infill and, subsequently,- drying (810) said infill, wherein the method comprises, during said drying (810) the infill, sucking powders and / or artificial grass filaments fromsaid infill.

7. Plant (99) for separating an infill for artificial grass surfaces, the plant (99) comprising:- one or more capture devices, each capture device comprising a main body (21) defining a cavity (22) and comprising an inlet (23) and an outlet (24), and,- a movement system (75) of the infill for generating a flow of said infill from said inlet (23) to said outlet (24) through said cavity (22); wherein each capture device comprises:- capture elements (20) distributed inside said cavity (22);- an electrical system for electrostatically charging said capture elements (22);- a removal system for removing artificial grass filaments (3) from said capture elements (20).

8. Plant (99) according to claim 7, wherein said capture elements (20) are made of electrically insulating material, wherein said main body (21) has a main development direction (100) which goes from the inlet (23) to the outlet (24) of the cavity (22), wherein said main development direction (100) is inclined and descending from the inlet (23) to the outlet (24), wherein said flow of the infill is parallel to said main development direction (100), wherein said capture elements (20) are homogeneously distributed inside said cavity (22), wherein said capture elements (20) have a respective development direction perpendicular to the main development direction (100) of the main body (21), wherein said respective development directions are all parallel to each other, wherein said capture elements (20) have solid cylindrical shape with axis along said main development direction (20), wherein said capture device comprises flow deflectors (30) distributed in the cavity, and having plate-like shape, with a development direction parallel to said respective development direction of said capture elements (20), and wherein said flow deflectors (30) are shaped to create a tortuous path around the main development direction (100) of the main body (21).

9. Plant (99) according to claim 8, wherein each capture device comprises a control system programmed for commanding said electrical system to electrostatically charge and discharge said capture elements (20) and for commanding said removal system to remove said artificial grass filaments (3) from said capture elements (20) while said capture elements (20) are electrically discharged, wherein said removal system comprises a suction system for sucking air from said cavity (22) and wherein the control system is programmed for commanding said suction system for sucking air from said cavity (22) along a direction parallel to said respective main development direction (100) of the capture elements (20).

10. Plant (99) according to any one of claims from 7 to 9, further comprising:- a granulometrical screening device (400) comprising a plurality of filters (6-10) each having a different particle size, a feeding inlet (11), a waste outlet (12) and a plurality of discharge outlets (13-17), wherein said filters of said plurality of filters are arranged in an ordered sequence with decreasing particle size and vertically stacked, wherein said feeding inlet (11) is located above a first filter (6) of said plurality of filters , wherein said waste outlet (12) is located upstream of a first filter (6) of said plurality of filters, wherein each discharge outlet is located downstream of a respective filter of said plurality of filters, wherein a first filter (6) of said plurality of filters has particle size between 1500 pm and 3500 pm, wherein a second filter (7) of said plurality of filters has particle size between 1000 pm and 2000 pm, wherein athird filter (8) of said plurality of filters has particle size between 600 m and 1400 pm, wherein a fourth filter (9) of said plurality of filters has particle size between 500 pm and 800 pm, wherein a fifth filter (10) of said plurality of filters has particle size between 300 pm and 600 pm, wherein the implant (99) comprises a plurality of said capture devices, wherein each capture device is arranged directly downstream of a respective discharge outlet of said plurality of discharge outlets of the granulometrical screening device (400);- a plurality of densimetric separation devices, each comprising a first (31) and a second (32) opening outlet, wherein each densimetric separation device is configured for conveying towards said first (31) opening outlet a first infill subtraction (601) and towards said second (32) opening outlet a second infill sub-fraction (650) having a density lower than said first infill sub-fraction (601), wherein each densimetric separation device is arranged directly downstream of a respective capture device;- a plurality of air flow separation devices, each separation device comprising a hopper (711), a separation chamber (713), a fan (712) for generating said air flow in said separation chamber (713 ), a first outlet (701) proximal to said fan (712) and a second outlet (702) distal to said fan (712), wherein one (705) of said air flow separation devices is disposed directly downstream of one (505) of said capture devices, and wherein one or more other devices of said air flow separation devices are arranged directly downstream of a respective densimetric separation device;- a dryer (300) arranged upstream of said capture devices, and / or of said granulometrical screening device (400), and / or of said densimetric separation devices and / or of said air flow separation device;- a suction and filtering device (310) structured for sucking air from said dryer (300) and for filtering said sucked air to separate powder and / or artificial grass filaments (301);- a buffer tank (200) upstream of said dryer (300) comprising an element for mixing (800) said infill; wherein the movement system (75) of the infill comprises a plurality of mechanical movement devices distributed along a path to generate a substantially continuous flow of infill along said path, wherein said mechanical movement devices are selected from the group: elevators (70), screw conveyors (72), belt conveyors and chutes (73).

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