Apparatus and method for separating materials of various type

A method for separating materials of various type having different softening temperature values, includes pouring a mixture of flakes and fragments of materials on a movable receiving and conveying device in a uniformly distributed manner and advancing it along a first portion of path; actuating an electromagnetic inductor to heat an outer metal surface by electromagnetic induction, which surface is included in the movable receiving and conveying device to achieve a first lower softening temperature corresponding to a first material of the mixture; subjecting the mixture to a separating action during which a first fraction, remains stuck to the outer metal surface, whereas a remaining second fraction of materials having higher softening temperatures than the first softening temperature freely slips by gravity towards a lower receiving zone.

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus and a method allowing to separate materials of various type based on the different respective softening temperatures.

The apparatus and the method are particularly useful in the field of treating and recycling of plastics materials obtained from post-consumption objects, such as polyethylene terephtalate PET and other materials, from which substances and/or further contaminant materials are to be removed.

BACKGROUND OF THE ART

For recycling plastics materials, particularly PET, it is known to grind objects such as post-consumption bottles or containers, such as to obtain a mixture of materials in the form of flakes or fragments. This mixture, in addition to the prevailing amount of PET material, also inevitably contains a certain amount of contaminating substances or materials which affect the recycled product obtained. The presence of these contaminating materials beyond a certain tolerated limit results in the recovery plastics material having an industrially unsatisfactory pureness degree.

The contaminating substances very often include polymeric materials such as poly vinyl chloride (PVC), acrylic materials, polystyrene and so-called “low-melting” materials, i.e. having relatively lower melting temperatures and softening temperatures than PET, where the softening temperature is intended as the temperature at which the material achieves a certain state of fluidity, thereby acquiring a soft or pasty consistency.

It is thus necessary to separate these “low-melting” materials from the PET. To the purpose, separating systems are presently used comprising a conveyor belt which receives said mixture of flakes and fragments and is heated, by means of hot air flows dispensed by suitable internally-arranged nozzles. The flakes of low-melting material, particularly of PVC, in contact with the hot belt progressively acquire a soft or pasty consistency, which causes them to become sticky. Through this adhesive effect, only the PVC particles, and not the PET flakes, are caused to adhere to the belt. Thereby, the aim is to allow the PET flakes to drop from the belt to a suitable collection area after they have reached the end of the conveyor belt, whereas the PVC fragments are still maintained adherent to the belt for a further portion of path. A suitable scraper is provided to remove the PVC fragments from the belt.

Drum separation systems are also known, which are heated from the inside by means of hot liquids or hot air, at such temperatures as to cause the softening of the low-melting materials to be removed. Similarly to the above-described belt systems, suitable scrapers remove the fragments of low-melting material attached to the drums, whereas the PET flakes are allowed to drop freely in a separate zone.

The prior art systems described above entail limits both from the operational and versatility point of view and from structural and constructive point of view.

Particularly, both in the case of the conveyor belt and in the case of the drum system, the hot air heating should be necessarily provided from the inside in order to prevent the lighter mixture particles from being swept away from the supporting and advancement surfaces on which they are laid, and this implies that quite complex internal circuits should be provided for the hot air. Furthermore, the use of hot air to heat the surfaces of the belt or drums entails a considerable energy consumption. Generally, the hot air heating system has a number of difficulties both in terms of construction and in terms of management and operation. Furthermore, in the currently known systems, the scraping action often leads to unsatisfactory results. In fact, often the low-melting materials reach the scrapers in a still soft and pasty state because they are still hot, and instead of being detached by the scrapers they tend to remain at least partially attached to and spread on the surface of the belt or roll thereby negatively affecting the proper operation of the equipment and the quality, in general, and efficacy of the material recovery process.

Accordingly, there is a need to research a technical solution which allows overcoming the inherent limitations of the conventional separation systems described above.

OBJECTS OF THE INVENTION

An object of the present invention is to provide a method and an apparatus which provide a general improvement in the separation of recyclable materials, compared to the known systems.

Another object is to structurally simplifying the systems for separating the recyclable materials, thereby making them cost-effective in terms of construction and operation, and ensuring a high level of separation and purity of the plastics material being recovered while achieving a higher energy efficiency than the prior art systems currently used.

BRIEF DESCRIPTION OF THE INVENTION

These and further objects and advantages of the invention can be achieved by means of a method according to claim1, and an apparatus according to claim12.

According to a first aspect of the invention, a method is provided for separating materials of various type having different softening temperature values, comprising the steps of:pouring a mixture of flakes and fragments of said materials onto movable receiving and conveying means in an uniformly distributed manner, andadvancing said mixture along a first portion of path;actuating electromagnetic inductor means in order to heat an outer metal surface by means of electromagnetic induction, which surface is included in said movable receiving and conveying means, such as to reach a first lower softening temperature corresponding to a first material included in said mixture,subjecting said mixture to a separating action during which a first fraction of said mixture composed of said first material, adheres to said outer metal surface due to the soft or pasty consistency thereof, which is acquired upon contact with said outer metal surface heated at said first softening temperature, said first fraction of mixture remaining stuck to said outer metal surface along a second portion of path whereas the remaining part of said mixture, which defines a second fraction composed of materials having softening temperatures higher than said first softening temperature slips away from said outer metal surface by gravity along a third portion of path and falls freely to a receiving zone located below,removing by scraping away said first fraction of mixture from said outer metal surface and receiving said removed first fraction in a collection zone which is separated from said receiving zone and dedicated to said first material,CHARACTERISED IN THAT before said scraping the following is provided:directing a jet of refrigerating-cleaning-substance comprising air and carbon dioxide (CO2) at a low temperature to said first fraction of mixture advancing along said second portion of path, such as to cool and solidify said first fraction of mixture in order to promote the detachment of the latter from said outer metal surface.

Particularly, in an embodiment of the method a step of cryogenic sandblasting is provided, in which the used refrigerating-cleaning-substance X comprises air and carbon dioxide (CO2) particles in the solid state (dry ice). According to another embodiment of the method, the used refrigerating-cleaning-substance X comprises air and carbon dioxide snow.

In a second aspect of the invention, an apparatus is provided for separating materials of various type having different softening temperature values, comprising:receiving and conveying means configured to support and advance a mixture of flakes and fragments of said materials along a first portion of path, and comprising a metal outer surface suitable to receive said mixture;supplying-distributing means configured to pour and uniformly distribute said mixture onto said receiving and conveying means,heating electromagnetic inductor means to heat said metal outer surface by means of electromagnetic induction, such as to reach a first lower softening temperature corresponding to a first material included in said mixture;control means to actuate and adjust said electromagnetic inductor means at a softening temperature of a first material included in said mixture, such as to maintain the adhesion of said first material to said metal outer surface (6;106) along a second portion of path due to the effect of the soft or pasty consistency acquired by means of the heating action,scraping means to remove a first fraction of mixture composed of said first material from said metal outer surface in order to direct it to a dedicated collection zone;said receiving and conveying means being configured to cause, during the advancement, the fall by gravity, along a third portion of path, of a remaining part of mixture defining a second fraction composed of one or more materials having softening temperatures higher than said first softening temperature,CHARACTERISED IN THAT IT COMPRISESdispensing and treatment means being configured to direct a jet of refrigerating-cleaning-substance comprising air and carbon dioxide at low temperature to said first fraction of mixture advancing along said second portion of path, in order to cool and solidify said first fraction of mixture such as to promote the detachment of the latter from said outer metal surface.

By means of the method and apparatus according to the invention, a general improvement in the separation of recyclable materials is obtained, and a considerable reduction in the energy consumption related to the process as well as a high level of separation and purity of the plastic material being recovered are achieved. Reducing the energy consumption also results in advantages in terms of impact on the environment.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the annexed Figures, an apparatus1,100,200,300,400is shown to separate materials of various type having different softening temperature values. In other words, the apparatus1,100,200,300,400allows to separate and recover materials of various type based on the different respective softening temperatures.

The apparatus is thus a thermal apparatus-separator. The apparatus is particularly useful in the field of recovering and recycling materials, such as the materials coming from post-consumption plastic containers or bottles, such as polyethylene terephthalate PET and other materials, from which substances and/or further undesired contaminating materials are to be removed. Accordingly, the apparatus results to be a refiner apparatus capable of removing from a certain crushed material in granules or in flakes, the undesired substances or products which have a softening or melting temperature lower than the material to be purified.

The softening temperature is the temperature at which a number of substances achieve a certain fluidity status before reaching the step of complete melting. In other words, a plastic material at a respective softening temperature starts acquiring a soft or pasty consistency which makes the latter sticky. This soft and pasty consistency is exploited by the apparatus and method of the present invention in order to obtain a temporary adhesion of the material to a certain surface.

In the description below, reference will be made to “low-melting” materials to designate materials having a melting temperature, and thus softening temperature lower than the main material to be depurated. For example, materials such as PVC (softening temperature of 50÷70° C.) or polystyrene PS (softening temperature of 80÷90° C.)) can be considered low-melting materials as compared with the PET material to be depurated (which has a melting temperature of about 260° C.).

In the field of treatment and recycling of materials, particularly polyethylene terephthalate (PET), the objects recovered from municipal waste and comprising bottles, or container in PET are subjected to steps of washing and removal of labels, caps and other undesired bodies such as bags or others, and are then brought to a crushing or grinding step in order to be reduced in flakes. These flakes of PET often result still accompanied by particles or fragments of other materials, such as polyvinylchloride PVC, polystyrene PS, other possible polymeric materials, which must be removed in order to ensure the desired purity. At this stage, the apparatus and method according to the present invention successfully intervene, such as described below.

With reference toFIGS. 1 to 7, the apparatus1comprises receiving and conveying means. Particularly, the receiving and conveying means comprise support and advancing plane means2, configured to support and advancing a blend or mixture M of flakes, or granules, fragments of different materials along a first portion of path P1, and supplying-distributing means3configured to pour and uniformly distribute the mixture M on said support and advancing plane means2. In the embodiment described and illustrated herein, the support and advancing plane means comprise a conveyor belt2, actuated by a drive motor20. The conveyor belt2has a support surface of a material suitable to resist also very high temperatures without deteriorating, such as to be able to treat any recyclable plastic material. The supplying-distributing means comprise a vibrating supply unit3provided with a hopper element, a metering star valve12, and an inclined distribution plane25. The inclined distribution plane has a slope ranging between 5 and 10 degrees but can also have different values based on the characteristics of the materials being worked. The vibrating supply unit3is actuated and vibrated by an electric motor or electromagnet or other equivalent actuating device. The vibrating supply unit3is provided with a distribution element13having an undulated profile which functions to uniformly distribute the mixture M thereby defining a thin layer of mixture M on the conveyor belt2.

The apparatus comprises pre-heating means4which are arranged to pre-heat the mixture M along said first portion of path P1, such as to prepare one or more types of materials included in the mixture M to a softening thermal action which is subsequently completed. The pre-heating means4are configured to irradiate thermal energy on the mixture M advancing along the first portion of path P1. The pre-heating means4are positioned outside the conveyor belt2, at a certain distance from the movable support surface suitable to receive the mixture M.

The thermal energy irradiated from the pre-heating means4must be such as not to cause the adhesion of the low-melting materials to the conveyor belt2, but must only prepare these low-melting materials and then promote a quicker softening of the latter which is completed in a suitable section of the apparatus1situated downstream of the conveyor belt2relative to the advancing direction of the mixture M, such as described below. In the case where the PET material is required to be treated and depurated, the pre-heating means4can pre-heat the mixture M at a temperature indicatively ranging between 120° C. and 160° C. The radiant power of the pre-heating means4, and thus the pre-heating temperature, can be certainly adjusted and controlled based on specific process requirements and based on the characteristic of the materials being treated, as well as the contaminating materials being present, and then can be either lower or greater than the values stated above.

Advantageously, this configuration which provides the pre-heating means4arranged externally above at a certain distance from the support surface of the conveyor belt2achieves the technical effect of directing the heating action mainly and directly to the mixture M. The particles/fragments of mixture thereby receive the heating action in a direct manner, unlike in the prior art systems wherein it is the belt that is first heated and then it releases the heat to the mixture that is externally placed thereon. This difference is due to the fact that in the prior art systems the aim is to cause the low-melting particles to adhere directly to the conveyor belt. In this embodiment of apparatus according to the present invention, on the other hand, the adhesion of the low-melting materials should not occur on the conveyor belt2(where only a preparation for the adhesion is carried out) but on thermal separating means5placed downstream, which will be detailed herein below.

Due to the fact that the pre-heating of the mixture M is carried out externally and from above, any particles having a very low melting or softening temperature are prevented from undesirably adhering to the conveyor belt2.

Particularly, the pre-heating means comprise infrared lamps4that are positioned above the conveyor belt2and distributed along the first portion of path P1, which are capable of irradiating thermal energy directly on the mixture M.

The distribution element13with undulated profile of the vibrating supply unit3, which is particularly configured to uniformly distribute the mixture M onto the conveyor belt2according to a thin layer of mixture M causes all the mixture flakes, particles and fragments to be in direct contact with the conveyor belt2and not overlap one another. This has the effect of causing each and every particle or fragment to be exposed to the heat source and invested by the action of the infrared lamps4, thereby being heated but not adhered to the conveyor belt2. A control unit10is provided through which the infrared lamps4can be controlled to adjust the proper amount of energy to be irradiated according to the recyclable materials being worked.

The apparatus1comprises rotating thermal separating means5, which are provided with a metal outer surface6suitable to receive the mixture M coming by gravity from the support and advancing plane means2, (in this case, from the conveyor belt2) and electromagnetic inductor heating means7configured to heat this metal outer surface6by means of electromagnetic induction.

The thermal separating means particularly comprise a cylindrical unit5that can be a roll or a drum, rotated by a respective drive motor21.

The roll or drum is externally delimited by a cylindrical layer or cylindrical metal sheet, on which said outer metal surface6is provided. The metal which the outer cylindrical layer or outer cylindrical sheet, and hence said outer metal surface6, consist of is steel or another metal suitable to be heated by electromagnetic induction. The cylindrical unit5is rotatable about a respective horizontal axis. The electromagnetic inductor means comprise an electric inductor element7situated at the outer metal surface6. The electric inductor element7is particularly configured as a reel or electrode element extending according to a coil line, thereby defining one or more turns. The electric inductor element7can be nevertheless configured according to different shapes in order to fit the geometry of the cylindrical separation unit5and/or entire apparatus1.

In the electric inductor element7an electric current is made to flow, which is alternated or in any case variable in time, which produces a time-variable magnetic field. The variation of the magnetic field flow generates an induced electromotive force in the metal layer or metal sheet of the separation roll5which, in turn, generates induced electric currents, i.e. parasite currents that dissipate energy in the form of heat thereby causing the immediate heating of the metal surface6. The energy efficiency is very high, above 90%, and the energy saving is considerable. The induction heating on the surface6is quick and homogeneous, can be adjusted very precisely and be strictly localized on the zone of interest. The electric inductor element7is electrically powered by a generator with a settable power and frequency depending on several parameters, such as the geometry of the electric inductor element7, the geometry and speed of the cylindrical separation unit5, further possible parameters and also depending on the characteristics of the plastic material being worked which is desired to be brought to the softened condition. The provision of any measures for thermally insulating determined zones of the apparatus1, particularly of the cylindrical unit5, also positively affects the calibration of the electric inductor element7, particularly reducing the absorbed power in order to obtain the desired heating temperature. In an embodiment, a thermal insulating material, which allows containing the thermal dispersions towards the inside, can be provided in the cylindrical unit5, beneath the outer metal surface6, thereby increasing the thermal efficacy of the system and further reducing the energy consumption.

The electromagnetic inductor means7are operatively connected to, and controlled by, the control unit10, which is provided with a temperature controller, which allows adjusting the heating temperature of the metal outer surface6of the roll or separation drum5based on the specific material intended to be softened and adhered to the latter.

With reference to the first embodiment of apparatus1, the control unit10actuates and adjusts the electromagnetic inductor means7to a softening temperature TR1of a first specific material M1included in the mixture M, such as to maintain this first material M1adhering to the metal outer surface6along a second portion of path P2, during the rotation of the cylindrical separation unit5. A first fraction F1of mixture, composed of this first material M1, is thus removed from the main stream of the mixture M.

The cylindrical separation unit5is configured to cause, due to the rotation thereof, the fall by gravity, along a third portion of path P3, of a remaining part of mixture M which, unlike the first material M1, does not reach the softening state and thus does not stick to the metal outer surface6. This remaining part of mixture thus defines a second fraction F2composed of one or more materials having higher softening temperatures than the first softening temperature TR1. The flakes/particles of the second fraction F2, during the rotation of the roll or drum5, advance to a curved downward trajectory having a slope gradually increasing to a point where the static friction force is no longer capable of holding the flakes which thus slip downwards from the metal surface6by gravity.

The apparatus1further comprises scraping means8to remove the first fraction F1, composed of first material M1adhering to the outer metal surface6, in order to send it to a dedicated collection zone R1. A cold water circuit can be provided for cooling the scraping means8.

The scraping means8comprise a scraper for removal which can be a doctor-blade or spatula element or other element suitable to remove the particles/fragments of material that are stuck to the metal surface6. The scraper8is located in an zone angularly spaced from the zone where the remaining part of mixture, such as the second fraction F2, detaches from the metal surface6.

The apparatus1further comprises dispensing and treatment means11, particularly a cooling unit11configured to cool the first fraction F1, through a jet of a cleaning-refrigerating substance X, in order to facilitate the scraping detachment operation carried out by the scraper element8. Particularly, the cleaning-refrigerating substance X comprises air and carbon dioxide (CO2) at low temperature (about −78÷−80° C.), and is directed to the first fraction F1of mixture M to cool, solidify and crystallize the latter, such as to promote the detachment of the latter from the outer metal surface6. The effective temperature decrease to which the material to be treated is subjected causes a quick hardening of the particles of the fraction F1thereby making them more easily detachable from the surface they are stuck to.

The dispensing and treatment means11comprise one or more dispensing nozzles which act to subject the fraction F1to treatment through the refrigerating-cleaning-substance X of air and carbon dioxide (CO2). Particularly the fraction F1is subjected to a cryogenic sandblasting treatment (also designated as “cryo-sandblasting”) in which pressurized air is used which contains dry ice particles, i.e. carbon dioxide (CO2) in the solid state.

The particles of solid carbon dioxide, pushed by a high-speed compressed air jet, hit the flakes, granules, fragments of material M1thereby causing them to detach or considerably facilitate and make the next scraping step effective. A removal of the material is thereby obtained both due to a mechanical action of the dry ice particles and a synergy between cooling thermal shock and subsequent scraping action.

Advantageously, the carbon dioxide particles after the impact go back to the gaseous state and are dissolved in the air, without leaving any residual element, and thereby without altering the physical-chemical characteristics of the material being treated. Furthermore, due to the use of the air with dry ice, the surfaces of the receiving and conveying means on which the mixture M is adhered are maintained perfectly clean.

According to another embodiment, the refrigerating-cleaning-substance X comprises air and carbon dioxide in the state of carbon dioxide snow. Also in this case, the refrigerating-cleaning-substance X considerably facilitates the detachment of material from the respective surface to which it is adhered, does not leave any residues, and therefore does not alter the physical-chemical characteristics of the material being treated.

The refrigerating-cleaning-substance X can be stored in a suitable storage unit30included in the apparatus1.

The dispensing and treatment means either comprise one or more nozzles11arranged in a stationary position, or one or more nozzles11mounted to a movable support, particularly translating from a zone to another in order to cover an area on which the fraction F1of mixture is deposited, which is to be treated with said refrigerating-cleaning-substance X. The nozzle11is positioned upstream of the scraper8relative to the direction of rotation of the cylindrical separation unit5, such as to cool, by solidification, the particles of material M1that are about to interact with the scraper element8. The electric inductor element7, on the other hand, is positioned downstream of the scraper element8but upstream of the zone where the mixture M falling from the conveyor belt2comes from above. This position of the electric inductor element7has the technical effect of heating, immediately downstream of the scraper element8, the subsequent portions of outer metal surface6which have been affected to a certain extent by the cooling action carried out by the cooling nozzle11and that, as soon as they have passed the scraper element8, should be brought back again to the proper temperature before receiving again another amount of mixture M coming from the conveyor belt2.

According to another embodiment, a cooling unit11can be provided comprising an impeller blower or a blower with air compressor and a respective nozzle to expel a pressurized cold air knife, the nozzle being positioned at the respective scraper element8, which is cooled by means of a water circuit.

Due to the electromagnetic inductor element7, the heating of said outer metal surface6portions is much more quick and effective, than the prior art systems. As the apparatus1is provided with such quick and effective heating means, the zone upstream of the scraper element8can be effectively and intensely cooled such that the scraping of the first material M1can be optimized: after the scraper element8has been passed the cooled metal surface6zone is quickly brought back to the temperature suitable to cause the softening of the subsequent dose of material M1received. Due to the above-described configuration comprising the electromagnetic inductor element7and the cooling unit11, and due to the particular position and mutual arrangement of the electromagnetic inductor element7and the cooling nozzle, the cylindrical separation unit5can be easily and quickly subjected to continuous local cooling and heating cycles.

To the control unit10are operatively connected the drive motor20of the conveyor belt2, the vibrating supply unit3, the pre-heating means4, the drive motor21of the cylindrical separation unit5, and the electromagnetic inductor element7. The cooling unit11can also be operatively connected to, and controlled by, the control unit10. The control unit10intervenes to adjust, in a mutually related manner, based on the materials of the mixture M that is to be separated, the advance speed of the conveyor belt2, the pre-heating temperature, the rotation speed and the temperature of the cylindrical separation unit5, the vibratory movement of the vibrating supply unit3and the flow rate/pressure of the cleaning-refrigerating substance X that the cooling unit11directs to the cylindrical separation unit5.

An operating mode of the apparatus1, according to which a first material M1(e.g., PVC), or a subset of low-melting materials having the same softening temperature, is separated from the remaining part of mixture, is described below.

Assuming that a mixture is mainly composed of PET flakes but also contains a certain amount of another material, such as PVC (designated with M1) the operation will be as follows.

The mixture M is continuously poured from the vibrating supply unit3and is uniformly distributed on the top surface of the conveyor belt2, such as to form a thin layer of flakes/fragments/particles. A suitable vibratory frequency of the vibrating supply unit3, a proper inclination of the inclined distribution plane25and the particular conformation of the undulated profile of the vibrating supply unit3result in the mixture flakes, particles and fragments being all distributed in direct contact with the conveyor belt2, without overlapping one another, such as to be well exposed to the infrared lamps4to be pre-heated while they advance along the first portion of path P1. Additionally, by distributing the flakes and particles well scattered on the surface of the conveyor belt2, the flakes and particles are advantageously prevented from overlapping one another on the outer metal surface6upon falling onto the cylindrical separation unit5, each of the flakes and particles thus coming in contact with the metal surface. Thereby, it is ensured that all the contaminating particles to be removed will stick to the cylindrical separation unit5to be then scraped away therefrom.

Once the mixture M has reached the end of the conveyor belt2, it falls by gravity onto the below-located cylindrical separation unit5, whose outer metal surface6is, due to the electric inductor element7, at a first PVC-typical softening temperature TR1. The PVC particles, which were previously pre-heated on the conveyor belt2, adhere to the hot outer metal surface6upon contact therewith, remain stuck thereto due to the softening condition they have acquired and are carried, during rotation, to a second portion of path P2. A first fraction F1of mixture M is thus separated whereas the remaining part of said mixture, which defines a second fraction F2composed of materials having higher softening temperatures than the first softening temperature TR1, in this case composed of PET material, slips away by gravity from the surface of the cylindrical separation unit5following a third portion of path P3and falling freely into a receiving zone Z located below, while the nozzle of the cooling unit11progressively cools the first fraction F1before it reaches the scraper element8from which it is scraped and dropped into a PVC-dedicated collection zone R1. The PET being recovered is thus depurated and free of PVC traces.

FIGS. 8 to 14show a second embodiment of the apparatus according to the invention, designated with numeral100. The apparatus100comprises a number of parts similar to the first embodiment described above. These parts have been designated with the same numerals as used in the first embodiment increased by 100.

In this embodiment, the thermal separating means comprise a plurality of cylindrical units105, which define as many separation stages. In the exemplary embodiment shown herein, three cascade-separation thermal cylindrical units105, defining three respective separation stages for the materials of the mixture M, which are sequentially designated as first separation stage S1, second separation stage S2, and third separation stage S3. The apparatus100can be configured with a different desired number of separation thermal cylindrical units105, and separation stages accordingly, based on particular usage requirements.

The apparatus100shown inFIGS. 8 to 14comprises a first cylindrical unit105A, which is located downstream of the conveyor belt102and is provided with a first metal surface106A, a second cylindrical unit105B having a second metal surface106B and located beneath the first cylindrical unit105A in a suitably offset position such that it can intercept those materials that fall from the first metal surface106A. The apparatus100further comprises a third cylindrical unit105C having a third metal surface106C, which is located beneath the second cylindrical unit105B in a suitably offset position relative to the latter such that it can intercept the materials that slip downwards from the second metal surface106B. The three cylindrical separation units105A,105B,105C are driven by respective motors121A,121B,121C.

The three cylindrical separation units105A,105B,105C are sequentially arranged one beneath the other, and are configured to operate at progressively increasing temperatures in order to obtain separation and collection of a plurality of materials M1, M2, M3, M4of various type having respective progressively increasing softening temperatures. Similar to the first embodiment described above, each of the three cylindrical units105A,105B,105C comprises a roll or drum, which rotates about a respective horizontal axis and a respective scraper element108A,108B,108C. The electromagnetic inductor means included in the apparatus100, comprise for each of the three cylindrical separation units105A,105B and105C, a respective electric inductor element107A,107B,107C. Each electric inductor element107A,107B,107C is positioned downstream of the respective scraper element108A,108B,108C, relative to the direction of rotation of the respective cylindrical unit105A,105B,105C.

The cooling means111included in the apparatus100comprise, for each cylindrical unit105A,105B,105C, one or more respective nozzles111A,111B,111C at the respective scraper element108A,108B,108C in order to direct one or more jets of cleaning-refrigerating substance X comprising pressurized air and carbon dioxide CO2 either in the solid state or in the state of carbon dioxide snow.

The apparatus100includes a control unit110to which the drive motor120of the conveyor belt102, the vibrating supply unit103, the pre-heating means104, the drive motors121A,121B,121C of the cylindrical separation units105A,105B,105C, and the electromagnetic inductor elements107A,107B,107C are operatively connected. The cooling units111A,111B,111C can also be operatively connected to, and controlled by, the control unit110. The control unit110acts to adjust, in a mutually correlated manner, based on the materials of the mixture M to be separated, the advance speed of the conveyor belt102, the pre-heating temperature, the rotation speeds and the temperatures of the cylindrical separation units105A,105B,105C, the vibratory movement of the vibrating supply unit3, and the flow rates of cooling fluid that the cooling units111A,111B,111C direct to the respective cylindrical separation units105A,105B,105C.

An operating mode of the apparatus will be described below, which allows separating four different materials included in the mixture M: a first material M1, a second material M2, a third material M3and a fourth material M4having respective progressively increasing softening temperatures. Also in this case, for clarity, the fourth material M4can comprise PET, and the other materials can comprise “low-melting” products such as PVC, polystyrene, acrylic materials or others to be separated from PET.

In the first steps, the operation is similar to that of the first embodiment of a single separation stage-apparatus. The first cylindrical unit105A is heated to a first lower temperature to remove first the most “low-melting” material. The second cylindrical unit105B is heated to a second temperature higher than said first temperature associated with the first cylindrical unit105A. The third cylindrical unit105C is heated to a third temperature higher than said second temperature associated with the second cylindrical unit105B.

The second fraction F2that does not adhere to the first cylindrical unit105A and falls along a third portion of path P3, in this case, may also contain in addition to PET contaminating materials that were not removed during the first separation stage S1because having a higher softening temperature than the first softening temperature TR1. The second fraction F2falls onto the second cylindrical separation unit105B, to undergo the second separation stage S2, in a similar manner as performed by the first stage S1, and is directed to a second collection zone R2following a fourth portion of path P4. During the second separation stage S2, a third fraction F3is then removed from the mixture, which fraction is composed of a second material M2that is scraped away and collected into the suitable collection zone R2following the fourth portion of path P4. The remaining part of mixture, i.e. a fourth fraction F4composed of materials having softening temperatures higher than the second softening temperature TR2slips downwards by gravity from the second metal surface106B of the second unit105B thus falling freely to a subsequent receiving zone Z′ located below, where it is intercepted by the outer metal surface106C of the third cylindrical separation unit105C, and follows a fifth portion of path P5. From this fourth fraction F4of mixture a fifth fraction F5is removed, which is composed of a third material M3, which adheres to the third metal surface106C and is subsequently scraped and collected in the third collection zone R3. The last remaining fraction of mixture, composed of material M4falls freely from the third metal surface106C to be thereby recovered in high purity conditions.

The apparatus200embodiment shown inFIG. 15differs from the above-described embodiments in that the receiving and conveying means only comprise a conveyor belt202, having a metal support surface206. An electromagnetic inductor207is provided, which is located upstream of the receiving zone of the mixture M to heat by means of electromagnetic induction the metal outer surface206at the first softening temperature TR1in order to adhere the first fraction F1thereto which contains the first material M1. A dispensing and treatment unit211is further provided, with relevant storage tank230, for the cleaning-refrigerating substance X.

The operation of the apparatus200is similar to that described in the above embodiments, and the conveyor belt202acts in a similar manner as the cylindrical unit5either with roll or drum of the first embodiment of apparatus described above.

The embodiment of apparatus300shown inFIG. 16differentiates from the embodiments described above in that the receiving and conveying means comprise only one thermal separation unit305either with roll or drum, which is provided with a metal support surface306. An electromagnetic inductor307is also provided, which is placed upstream of the receiving zone of the mixture M in order to heat by electromagnetic induction the metal outer surface306to the first softening temperature TR1, such that the first fraction F1containing the first material M1adheres thereto. A dispensing and treatment unit311is also provided, with a relative storage tank330, for the cleaning-refrigerating substance X.

The operation of the apparatus300is similar to that described in the above embodiments.

FIG. 17shows a further embodiment of apparatus400which operates in a similar manner as the above embodiments but differs in that the receiving and conveying means are not provided with conveyor belt and comprise three cylindrical thermal separation units405A,405B,405C, which define as many separation stages (S1, S2, S3) being arranged in cascade one over the other and configured to operate at progressively increasing temperatures in order to obtain a separation and collection of a plurality of various types of materials (M1, M2, M3, M4) having respective progressively increasing softening temperatures. Each cylindrical unit405A,405B,405C, is rotatable about a respective horizontal axis, is provided with a respective metal outer surface406A,406B,4056C and a scraper element408A,408B,408C, as well as with a respective electric inductor element407A,407B,407C positioned downstream of a respective scraper element408A,408B,408C relative to the direction of rotation of the respective cylindrical unit405A,405B,405C.

To each cylindrical unit405A,405B,405C, one or more nozzles411A,411B,411C are associated for dispensing the cleaning-refrigerating substance X, similarly to what has been described above.

From what has been described and shown in the annexed drawings, it is understood that the method and apparatus described above allow obtaining very high efficacy in the separation of the various materials in the recycling process, very high levels of purity in the plastic material recovered. and allows a considerably reduced energy consumption, due to the particular configuration of the cylindrical thermal units coupled to the electromagnetic inductor heating means. The apparatus described herein results in a thermal apparatus with an operating principle based on the use of different melting temperature values, or more precisely softening of the materials.

Several tests have been conducted, for example with a power of the electromagnetic inductor means set to a value of about 15 Kw, and with temperatures lower than 200° C. to heat a 1 meter-diameter cylindrical separation drum, which have proved the efficacy of material separation, with purity levels of the PET material near to 100%, and the considerable energy saving associated therewith. By means of a suitable optimization of the geometries of the various parts of the apparatus, particularly the cylindrical thermal separation units and inductor elements, and by the adoption of suitable thermal insulation measures, a very high process performance can be obtained, thereby allowing the use of even lower powers necessary for operation.

From what has been described and illustrated above, it is understood that the apparatus1,100is also configured as a refining apparatus for PET or other materials. Similarly, the method can be also defined as a method for refining a material, such as recyclable PET.

The induction heating that is obtained by means of electromagnetic inductor means7,107has the advantage of preventing gas and heat dispersion, preventing the generation of flames and this also results in a general improvement in the workplace conditions for the operators, in addition to a limited environmental impact.

It should be understood that what has been said and shown with reference to the annexed drawings has been provided by way of illustration only of the general characteristics of the separation method and apparatus according to the present invention; accordingly, other modifications or embodiments can be made both to the method and the apparatus, either as a whole or parts thereof, without however departing from the claims below. Particularly, the geometrical conformation, dimensions, position, materials composing one or more parts of the apparatus can be suitably selected and/or optimized based on specific usage requirements.