Method and system for obtaining food-grade plastic material from a mixed waste material stream.

Abstract

This disclosure relates to a method (100) for obtaining food-grade plastic material (10) from a mixed waste material stream (PS). The method (100) comprises using a near-infrared spectroscopy system (222) and / or a visible spectroscopy system to distinguish a first type of plastic material from other types of material in the material stream (PS) (110a), separating the first type of plastic material from other types of material into a first plastic material fraction (110b), using a camera-based object recognition system (226) to distinguish the first type of food-grade plastic material from other types of material in the first plastic material fraction (111a), and separating the first type of food-grade plastic material from other types of material in the first plastic material fraction (111b), thereby separating other types of material from the first plastic material fraction, thereby obtaining food-grade plastic material (10). This disclosure further relates to a system (1) for obtaining food-grade plastic material (10).

Description

Technical Field

[0001] The present invention generally relates to methods for obtaining food-grade plastic materials from mixed waste material streams. The present invention also generally relates to systems for obtaining food-grade plastic materials from mixed waste material streams.

Background Art

[0002] Food packaging, bottles, and containers are just one example of products that can be manufactured from plastic. Plastic materials are beneficial as materials due to many useful properties, such as being lightweight, water-resistant, and long-lasting. Due to this combination of properties, plastic materials are widely used and required in many industries. However, when plastic materials are released into the natural environment, they cause problems for plants and wildlife. Therefore, it is important that used plastics are collected and sent to disposal sites.

[0003] Normally, plastics that reach disposal sites are sent for incineration, landfill, or recycled through chemical or mechanical processes. These are currently the main techniques used to manage plastic waste. However, there are many problems associated with the management of plastic waste. One problem is that when plastic waste is incinerated, valuable materials are lost and cannot be used further. Another problem related to the incineration of plastics is that the incineration process generates many products harmful to the human body and the environment, such as carbon monoxide, carbon dioxide, chlorine, and other hydrocarbons. These gases contribute to the problem of global warming. The problems associated with landfilling plastic waste are that it occupies landfill space and is labor-intensive. Furthermore, landfilled plastics tend to release harmful substances over time. Additionally, when disposing of plastic waste, the conversion of waste to energy is not efficient.

[0004] Therefore, recycling is an excellent method for processing plastic waste. When recycling plastics, the purity levels of various types of plastics are crucial; otherwise, the quality of the final product will suffer. For example, if the recycled material is a mixture of different materials, such as different types of plastics, it is impossible to achieve high-quality recycled plastic. Therefore, it is extremely important that plastic waste is properly sorted based on, for example, type, application or market use, and origin. Various processes may be used to sort plastics into different fractions. However, existing processes are generally overly labor-intensive, and the facilities used are not flexible enough to accommodate various conditions. Furthermore, existing processes cannot achieve sufficient purity levels for each type or fraction of plastic. As a result, plastic materials sorted by existing methods generally cannot be used to form virgin plastics during recycling. In other words, recycled plastics are typically of lower quality or purity and cannot be used for the same purpose as before recycling. A more precise method is needed to sort these types of plastic products efficiently and effectively, with high throughput and efficiency, while maintaining high purity levels in the resulting fractions. [Overview of the project]

[0005] In view of the foregoing, the object of this disclosure is to provide an improved method for obtaining food-grade plastic material from a mixed waste material stream.

[0006] The purpose of this disclosure is also to provide an improved system for obtaining food-grade plastic materials from mixed waste material streams.

[0007] Furthermore, the objective is to provide solutions that address at least some of the above criteria, namely, solutions that enable the recovery of mixed waste material streams with greater precision or sorting into different fractions to produce desired plastic materials with higher purity levels.

[0008] A further objective is to provide a method for sorting several different food-grade plastic materials into separate fractions with greater efficiency.

[0009] To achieve at least one of the above objectives, and other objectives that may become apparent from the following description, the present disclosure provides a method having the steps defined in claim 1. Preferred variations of the method will become apparent from the dependent claims.

[0010] More specifically, according to a first embodiment, a method is provided for obtaining food-grade plastic material from a mixed waste material stream, the method comprising: discriminating a first type of plastic material from other types of material in a material stream using a near-infrared spectroscopic system and / or a visible spectroscopic system; diverting the first type of plastic material into a first plastic material fraction from other types of material in a material stream, thereby separating the first type of plastic material from the material stream; discriminating the first type of food-grade plastic material from other types of material in a first plastic material fraction using a camera-based object recognition system; and diverting the first type of food-grade plastic material into a first food-grade plastic material fraction from other types of material in the first plastic material fraction, thereby separating other types of material from the first plastic material fraction, thereby obtaining food-grade plastic material.

[0011] This method may be advantageous because a camera-based object recognition system is provided to distinguish whether an object in the first plastic material fraction is food-grade plastic material. Food-grade plastic material is worth sorting because it is safe for food contact applications. Therefore, food-grade plastic material can be recycled and reused in food-grade products. If the recycled material is of mixed types, it cannot be used in food-grade products such as food packaging. This allows recycled material to be used in food-grade products, reducing the need to manufacture packaging for food-grade products from new materials. Since packaging can be made from recycled material, the energy consumption of packaging can be reduced. Furthermore, since the method can sort food-grade plastic material from a mixed waste material stream, the amount of material ultimately incinerated may be reduced.

[0012] To achieve food-grade plastic materials with sufficiently high purity levels, the materials are subjected to a distinction and separation step using a near-infrared spectroscopic system and / or a visible spectroscopic system to limit or reduce the amount of material entering the camera-based object recognition system. The first step of distinction and separation may be advantageous because it sorts out potentially relevant plastic materials from a mixed waste material stream. This performs the first separation of objects.

[0013] When distinguishing a first type of plastic material from other types of materials using a near-infrared spectroscopic system and / or a visible spectroscopic system, the distinction may depend on the composition of the first type of plastic material. Alternatively, the type of material may be combined with color, such that the first type of plastic material may be a material of a specific composition having a specific color. Once the first type of plastic material is distinguished, it is separated into a first type of plastic material fraction based on the information from the distinction step. In other words, the separation step separates the already distinguished first type of plastic material. Separation means that the first type of plastic material is separated from other types of materials so that the first type of plastic material and the other materials are separated into different streams or fractions. The first type of plastic material may be removed from the mixed waste material stream. Other types of materials may be removed from the mixed waste material stream.

[0014] The initial sorting performed in the first sorting and separation step reduces the amount of material that reaches the second sorting and separation step, which in turn reduces the number of objects that are stacked and may improve the accuracy or quality of sorting performed by the camera-based object recognition system. This may result in higher purity of the sorted material. Higher purity of food-grade plastic material may result in higher quality of the final product.

[0015] Since plastic materials can be identified by their material composition and through the use of intelligent sorting, the method enables highly accurate sorting while maintaining high throughput. This increases the purity of the recycled material. This method may be performed, for example, before the sorted plastic material enters further mechanical or chemical recycling processes.

[0016] When distinguishing a first type of plastic material from other types of materials, a camera-based object recognition system may be used to perform the distinction, for example, by reading invisible barcodes or visible barcodes, recognizing markings with visible symbols, recognizing markings with invisible symbols, or recognizing a logotype or part thereof, or any other preferred method. Plastic objects may have an EAN barcode, and the camera-based object recognition system can recognize the barcode and thereby distinguish whether the plastic object is food grade or not. The camera-based object recognition system may also be able to recognize various visible symbols or logotypes that the camera-based object recognition system has been trained to recognize as food grade objects. For example, there may be certain objects that the camera-based object recognition system can recognize, such as bottles.

[0017] As those skilled in the art will understand, the method may be further adapted to incorporate the capture, reading, and processing of information regarding tracers or markings embedded in plastic materials. A well-known technique is tracer-based sorting (TBS), which enables or enhances the identification of polymer types (e.g., fluorescence) and / or decodeable markers (e.g., digital watermarks) using traceable plastic additives or markers. Such TBS markers may be used in combination with identification of polymer types based on tracer-specific fingerprints.

[0018] The input material, i.e., the mixed waste material stream, may originate from a bale of mixed waste material or a bale of plastic material. The material may originate from municipal solid waste, which may have already been sorted at a municipal solid waste facility so that the input material can be a bale of the desired plastic. Therefore, if the input material is a bale of the desired plastic and the sorting performed by the camera-based object recognition system separates food-grade from non-food-grade, the sorting performed by the near-infrared and / or visible-spectrum system may be a purification step.

[0019] The resulting food-grade plastic material may have a purity level of at least 80% to 85%, preferably at least 85% to 90%, more preferably at least 90% to 95%, and most preferably at least 95% to 99.7%.

[0020] The method may further comprise: using a near-infrared spectroscopic system and / or a visible spectroscopic system to separate a second type of plastic material from other types of materials in a material stream, from which a first type of plastic material has been separated; separating the second type of plastic material from other types of materials in the material stream into a second plastic material fraction, thereby separating the second type of plastic material from the material stream; using a camera-based object recognition system to separate a second type of food-grade plastic material from other types of materials in the second plastic material fraction; separating the second type of food-grade plastic material from other types of materials in the second plastic material fraction into a second food-grade plastic material fraction, thereby separating other types of materials from the second plastic material fraction, thereby obtaining a second type of food-grade plastic material.

[0021] Adding a second set of sorting and separation steps to sort a second type of food-grade plastic material can be advantageous because it allows for handling more types of material simultaneously, thereby further improving the efficiency of the method. Sorting a second type of food-grade plastic material may also improve the recycling level. The additional step can also reduce the labor intensity of the method because it reduces the need to move materials that are not of the first type of food-grade plastic material back through the method in different settings regarding the types of materials being sorted. Another advantage is that the settings regarding the types of materials being sorted and the settings regarding potential washing do not need to be changed as frequently.

[0022] If the first type of plastic material has already been separated from the mixed waste material stream, the second type of plastic material is separated from the other types of mixed waste material in the material stream. The second type of plastic material fraction is then subjected to sorting by a camera-based object recognition system to determine which objects are food grade. This sorts out the second type of food grade plastic material.

[0023] As those skilled in the art will understand, the method may be adapted to obtain any required or desired number of food-grade plastic materials. By sorting a wider variety of plastic materials, the method can be easily adapted to the sorting systems required in a particular region or country.

[0024] The method may further comprise: using a near-infrared spectroscopic system and / or a visible spectroscopic system to separate a further type of plastic material from other types of material in a material stream, from which a second type of plastic material has been separated; separating the further type of plastic material from other types of material in the material stream into a further plastic material fraction, thereby separating the further type of plastic material from other types of material in the material stream; using a near-infrared spectroscopic system and / or a visible spectroscopic system to separate the further type of plastic material from other types of material in the further plastic material fraction; and separating the further type of plastic material from other types of material in the material stream into a further purified plastic material fraction, thereby separating other types of material from the further plastic material fraction.

[0025] Even after all plastic materials that could potentially become food-grade plastic materials, or all desired materials that could potentially become food-grade plastic materials, have been separated from the mixed waste material stream, valuable objects may still remain in the mixed waste material stream. Therefore, to further improve the efficiency of the method, there may be a further separation and separation step to distinguish and separate any further valuable plastic materials, thereby providing a further plastic material fraction. To increase the purity of the further plastic material fraction, the further plastic material fraction may be subjected to a second separation and separation step so as to provide a purified further plastic material fraction.

[0026] The method involves reducing the size of material items in a first type of food-grade plastic material fraction, subjecting the first type of food-grade plastic material fraction to an alkaline washing process and / or a high-temperature washing process, using a near-infrared spectroscopic system and / or a visible spectroscopic system to distinguish the first type of food-grade plastic material in the washed first type of food-grade plastic material fraction from other types of material, separating the first type of food-grade plastic material in the washed first type of food-grade plastic material fraction from other types of material, thereby separating other types of material from the washed first type of food-grade plastic material fraction, thereby obtaining a purified food-grade plastic material, and the second type of food-grade plastic material is If present, the method may further include reducing the size of material items in the second type of food-grade plastic material fraction, subjecting the second type of food-grade plastic material fraction to an alkaline washing step and / or a high-temperature washing step, using a near-infrared spectroscopic system and / or a visible spectroscopic system to distinguish the second type of food-grade plastic material in the washed second type of food-grade plastic material fraction from other types of material, and separating the second type of food-grade plastic material in the washed second type of food-grade plastic material fraction from other types of material, thereby separating other types of material from the washed second type of food-grade plastic material fraction, thereby obtaining a purified second type of food-grade plastic material.

[0027] Subjecting various types of food-grade plastic materials to the step of reducing the size of the materials in the various types of food-grade plastic material fractions and to the step of subjecting the various types of food-grade plastic material fractions to a washing process can be advantageous as it may improve the purity level of the resulting types of food-grade plastic materials. The material items in the selected type of food-grade plastic material fraction may be of mixed types before the size reduction. In other words, the material items or objects in the selected type of food-grade plastic material fraction may include two or more types of materials in which one or more types of materials are bonded together before the size of the items is reduced. By reducing the size of the material items, different types of materials may be split from each other, and as a result, it becomes possible to sort more accurately and with a higher purity in the discrimination and separation steps. Further, the washing step may remove stickers, markings, etc. on the materials in that type of food-grade plastic material fraction, thereby also making it possible to remove them in subsequent discrimination and separation steps. Therefore, a higher purity can be achieved.

[0028] The method may further comprise drying the materials in the first type of food-grade plastic material fraction and, if present, the materials in the second type of food-grade plastic material fraction after subjecting the first type of food-grade plastic material fraction and, if present, the second type of food-grade plastic material fraction to a washing process.

[0029] Since the material items may adhere to each other when in a wet state, it may be advantageous to dry the materials before they enter the final discrimination and separation steps. Wet materials may tend to adhere to each other or to other objects, and as a result, it may become difficult to separate the correct material items. By drying the material items, the purity level of the resulting plastic materials can be further enhanced.

[0030] The method may further include subjecting a first type of food-grade plastic material fraction and, if present, a second type of food-grade plastic material fraction to a washing step, and then subjecting the first type of food-grade plastic material fraction and, if present, the second type of food-grade plastic material fraction to a flotation separation step, thereby separating materials having a density higher than water and materials having a density lower than water. The flotation separation step may be advantageous in that it can separate lighter materials from denser materials, thereby further improving the purity level of the food-grade plastic material. Subjecting material items to the flotation separation step also provides an alternative method for sorting different types of materials. Certain types of materials float or sink, thereby sorting the materials based on their density.

[0031] The first type of plastic material may be a first type of high-impact polystyrene material, such that the food-grade plastic material is a food-grade high-impact polystyrene material, and if a second type of plastic material is present, the second type of plastic material may be a second type of high-impact polystyrene material, such that the second type of food-grade material is a second food-grade high-impact polystyrene material, and if additional types of plastic materials are present, the additional types of plastic materials may be a mixed high-impact polystyrene material.

[0032] Food-grade high-impact polystyrene materials are particularly valuable economically when the materials can be sorted into highly pure fractions by type. Thus, a method suitable for sorting food-grade high-impact polystyrene materials can provide the possibility of reusing the materials, as described above for food-grade plastic materials.

[0033] The camera-based object recognition system uses a camera to acquire images of objects in a first plastic material fraction and, if present, a second plastic material fraction, and a processor to distinguish objects by comparing the acquired images with a database of food-grade objects to determine whether the objects are food-grade.

[0034] A camera-based object recognition system may be provided with a database of food-grade objects and may recognize whether an object is food-grade by comparing images acquired by the camera. For example, by providing a database with images from various angles of known food-grade objects that should be distinguished as food-grade, the camera-based object recognition system may be able to determine whether different types of objects are food-grade or not. The image does not necessarily have to be a full-size image of the object; it may be a small part that can be classified as food-grade. This small part may be, for example, a logo or specific product text.

[0035] A camera-based object recognition system may distinguish objects by using a camera to acquire images of objects in a first plastic material fraction and, if present, a second plastic material fraction, and by inputting the acquired images into a machine learning model trained to identify food-grade objects in input images, thereby determining whether the objects in the acquired images are food-grade.

[0036] Therefore, a machine learning model may take action based on patterns and relationships it finds in the acquired image, as is known in the art. The actual processes performed within the machine learning model are typically unknown, as is known in the art. However, in this regard, it is important that the machine learning model is trained to recognize patterns and, based on its training, make predictions or decisions to identify food-grade objects. Therefore, the model may typically be trained using a set of input data related to or representing food-grade objects and corresponding output data indicating whether or not the object is food-grade. Based on such data, the machine learning model may be trained to make decisions based on patterns, features, etc., it finds in the acquired image. In other words, the machine learning model may determine whether or not an object is food-grade.

[0037] The camera-based object recognition system may further include a tracer-based sorting (TBS) unit, which uses a camera to acquire images of objects having TBS markers in a first plastic material fraction and, if present, in a second plastic material fraction; a processor to detect TBS markers in the acquired images; and a processor to distinguish objects by comparing the detected TBS markers with a database of TBS markers to determine whether the object is food grade.

[0038] A camera-based object recognition system may be advantageous to include a TBS unit that provides the possibility of detecting TBS markers present on objects in first and second plastic material fractions. The TBS markers may be visible, invisible, and fluorescent markings that provide information about the object to the TBS unit. This provides a complementary method for determining whether or not an object is food grade.

[0039] As those skilled in the art will understand, the method may include decrypting information embedded in such a TBS marker.

[0040] The method may further comprise using a near-infrared spectroscopic system and / or a visible spectroscopic system to separate a first type of plastic material and, if present, a second type of plastic material, from other types of materials in the material stream from which the first type of plastic material has been separated, or from other types of materials in the material stream from which the second type of plastic material has been separated, if present; and separating the first type of plastic material and, if present, the second type of plastic material, from other types of materials in the material stream, into a recovered plastic material fraction that is rejoined with a mixed waste stream.

[0041] After all types of plastic materials have been separated, it may be advantageous to include a separation and sorting step for materials in the mixed waste material stream. This allows material items of each type of plastic material to be sorted and reintroduced at the start of the mixed waste material stream. Material items of each type of plastic material may not be separated or sorted when they should for various reasons. This may be due to the stacking of material items, which may prevent all materials from being separated, or it may be due to oversight in the sorting step. Therefore, the recycling level of this method is further improved by giving material items that were overlooked in the first step of separation and sorting an additional opportunity to be separated and sorted into the correct type of plastic material. This loop may continue until the material items are correctly sorted. Thus, both the effectiveness and yield of this method are improved.

[0042] By rejoining the recovered material fraction into the initial mixed waste material stream, all types of plastic materials can be transported on a single means of transport, such as a single conveyor belt, or any other type of transport used. This results in a less complex system compared to a system in which all types of plastic materials are directly separated into their respective plastic material fractions. This configuration facilitates system expansion in subsequent stages, so rejoining the recovered material fraction is still advantageous even when only a first type of plastic material is being separated. Furthermore, in the case of only a first type of plastic material, it is also possible to direct the recovered material fraction into the first plastic material fraction. The method may further comprise separating ferrous materials from the mixed waste stream using a magnetic device and / or separating non-ferrous materials from the mixed waste stream using an eddy current separator, before separating the first type of plastic material.

[0043] Given the value of many ferrous and / or nonferrous materials, it may be advantageous to separate them from a mixed waste material stream. By separating ferrous and nonferrous materials, the materials can be recycled, which may further increase the profitability of the method. Separating ferrous and / or nonferrous materials may also lead to a reduction in the amount of material downstream in the mixed waste material stream, which can further facilitate the separation step. In this specification, “nonferrous materials” means nonferrous metals.

[0044] The method may further comprise using a wind sieve and / or screen to separate objects in the mixed waste stream with a maximum cross-sectional extension greater than 320 mm into a shredder stream, before distinguishing the first type of plastic material.

[0045] Material items with larger cross-sectional lengths may be separated, which further enhances the separation process and prevents larger material items from covering other material items and thus making them indistinguishable. Furthermore, since many smaller materials such as gravel and sand can be separated from the mixed waste material stream by such sorting, the separation of objects can also separate objects with cross-sectional lengths smaller than a given length.

[0046] The system may further include crushing the material in the crusher stream to a maximum cross-sectional length of less than 320 mm and rejoining the material into the mixed waste material stream.

[0047] Reducing the maximum cross-sectional length of an object to less than 320 mm can be advantageous, as this may allow these objects to enter a mixed waste material stream while covering other objects.

[0048] According to a second embodiment, a system is provided for obtaining food-grade plastic material from a mixed waste material stream. The system comprises a first sorting and sorting station configured to receive a mixed waste stream, and comprising a near-infrared (NIR) spectroscopy system and / or a visible spectroscopy system configured to distinguish a first type of plastic material from other types of material in the material stream, and a discharge unit configured to separate the first type of plastic material from other types of material in the material stream into a first plastic material fraction, thereby separating the material of the first type of plastic material from the material stream, and a first sorting and sorting station configured to receive the first plastic material fraction A food grade classification and sorting station comprising: a first camera-based object recognition system configured to distinguish a first type of food grade plastic material from other types of plastic material in a first plastic material fraction; and a discharge unit configured to separate a first type of food grade plastic material from other types of plastic material in the first plastic material fraction into a first food grade plastic material fraction, thereby separating other types of material from the first plastic material fraction, thereby obtaining food grade plastic material from a material stream.

[0049] In general, the features of this embodiment offer similar advantages to those discussed above with respect to prior embodiments of the present invention. The features of the method may be provided to the system individually or in combination. Therefore, to avoid excessive repetition, the features and advantages described above will not be repeated.

[0050] Further applications of the present invention will become apparent from the detailed description given below. However, while the detailed description and specific examples illustrate preferred variations of the concept of the present invention, it should be understood that they are given merely as examples, as various changes and modifications within the scope of the concept of the present invention will become apparent to those skilled in the art from this detailed description.

[0051] The aspects of the concept of the present invention, including its specific features and advantages, will be readily apparent from the following detailed description and accompanying drawings. The figures are provided to illustrate the general structure of the concept of the present invention. Throughout, similar reference numerals refer to similar elements. [Brief explanation of the drawing]

[0052] [Figure 1] This is a flowchart of a system for obtaining food-grade plastic material from a mixed waste material stream. [Figure 2] This is a flowchart of a system for obtaining food-grade plastic material from a mixed waste material stream, which has additional stations within the system compared to the system in Figure 1. [Figure 3] This is a schematic perspective of the classification and sorting station. [Figure 4] This flowchart illustrates the various steps in a method for obtaining food-grade plastic material from a mixed waste material stream. [Figure 5] This flowchart shows various steps in a method for obtaining food-grade plastic material from a mixed waste material stream, which has additional steps within the method compared to the method in Figure 4. [Modes for carrying out the invention]

[0053] The concept of the present invention will be described more fully below with reference to the accompanying drawings showing currently preferred modifications of the concept of the present invention. However, the concept of the present invention may be implemented in many different forms and should not be construed as being limited to the modifications described herein, but rather these modifications are provided for the purpose of thoroughness and completeness and will fully convey the scope of the concept of the present invention to those skilled in the art.

[0054] Figure 1 shows a flowchart of System 1 for obtaining food-grade plastic material 10 from a mixed waste material stream PS. System 1 comprises a first sorting and separation device 20. In the first sorting and separation device 20, a first sorting is performed. A first sorting and separation station 22 within the first sorting and separation device 20 receives the mixed waste material stream PS. The input material, i.e., the mixed waste material stream PS, may originate from a bale of mixed waste material or a bale of plastic material. However, it should be noted that if the plastic material is high-impact polystyrene material, the origin of the material may be from municipal solid waste that has already been sorted at a municipal solid waste facility, such that a bale of mixed polystyrene material has already been sorted and can be used in System 1.

[0055] Referring here to Figure 3, the first sorting and separation station 22 comprises a near-infrared (NIR) spectroscopy system 222 and / or a visible spectroscopy system configured to distinguish a first type of plastic material from other types of materials in the material stream PS, and a discharge unit 224 configured to separate the first type of plastic material from other types of materials in the material stream PS into a first plastic material fraction 2. When distinguishing the first type of plastic material from other types of materials, the distinction may depend on the composition of the first type of plastic material. The type of material may also be combined with color, so that the first type of plastic material may be a material of a specific composition having a specific color. After the first type of plastic material has been distinguished, it is separated into a first type of plastic material fraction 2 based on the information from the distinction. In other words, the first sorting and separation station 22 separates the first type of plastic material that has already been distinguished. In other words, the first sorting and separation station 22 separates a first type of plastic material that has already been distinguished from other materials present in the mixed waste material stream PS. Separation means that the first type of plastic material is separated from other types of materials into a different stream or fraction. The first type of plastic material may be removed from the mixed waste material stream PS, or other types of materials may be removed from the mixed waste material stream PS. Other materials separated from the sorting and separation station are represented by dotted arrows in the figure. All sorting and separation stations within System 1 may be stations of the same type but with different types of systems. In other words, there may be multiple locations of the same type of station within the system. An example of such a station is further described in relation to Figure 3.

[0056] The first classification and sorting device 20 further comprises a first food grade classification and sorting station 25 which includes a camera-based object recognition system 226 and a discharge unit 224. The first food grade classification and sorting station 25 receives a first type of plastic material fraction from the first classification and sorting station 22 and sorts the first plastic material fraction into food grade or non-food grade. This yields a first food grade plastic material 10.

[0057] When distinguishing a first type of plastic material from other types of materials, the distinction may be performed using a first food grade classification and sorting station 25 that utilizes a camera-based object recognition system 226, for example, by scanning an invisible barcode, recognizing a visible symbol marking, or recognizing a logotype. The plastic object may have a barcode, and the camera-based object recognition system 226 can recognize the barcode and thereby determine whether the plastic object is food grade. The camera-based object recognition system 226 may also be able to recognize various visible symbols or logotypes that it has learned to indicate a food grade object. For example, there may be specific objects that the camera-based object recognition system 226 can recognize, such as bottles. How the camera-based object recognition system 226 functions will be further explained with reference to Figure 3.

[0058] Moving on to Figure 2, an example of System 1 for obtaining food-grade plastic material 10 from a mixed waste material stream PS is shown, along with further stations within System 1. The stations already described in relation to Figure 1 also form System 1 in Figure 2 and will not be described further in this section. It should be emphasized that the stations within System 1 in Figure 1 are sufficient to work synergistically when sorting the mixed waste material stream PS.

[0059] Figure 2 shows examples of station types that may further constitute part of System 1. A station may form System 1 on its own or in combination with other stations. For ease of understanding, the stations are shown together. The various stations described below may be used individually or in any combination, depending on the requirements of the facility in which System 1 operates.

[0060] System 1 in Figure 2 further comprises a pre-sorting device 60. The pre-sorting device 60 comprises a bale opener 61 configured to open bales from which the mixed waste material stream PS may be derived. The pre-sorting device 60 further comprises a magnetic device 62 configured to separate ferrous materials from the mixed waste material stream PS into a ferrous material fraction 63. Ferrous materials often have high value and can be recycled by separating them, which can further increase the profitability of the system. The pre-sorting device 60 comprises an eddy current separator 62b configured to separate non-ferrous materials from the mixed waste material stream PS into a non-ferrous material fraction 63b. Non-ferrous materials or non-ferrous metals often have high value and can be recycled by separating them, which can further increase the profitability of the system.

[0061] The pre-sorting device 60 further includes a screener 64 that separates material items with a maximum cross-sectional length smaller than a predetermined screen range into a waste fraction 65 and material items with a maximum cross-sectional length larger than a predetermined screen range into a pre-crusher 68. For example, the predetermined screen range may be 20 mm to 320 mm. The pre-crusher 68 of the pre-sorting device 60 crushes the material so that the maximum cross-sectional length is smaller than the upper limit of the predetermined screen range. The crushed material items are then reintroduced into the mixed waste material stream PS.

[0062] The pre-sorting device 60 further includes a wind sieve that separates film material from the mixed waste material stream PS into a film fraction 67.

[0063] In the first sorting and sorting apparatus 20, a second sorting is performed by a second sorting and sorting station 23, which receives a mixed waste material stream PS from the first sorting and sorting station 22, from which the first type of plastic material has been separated. The illustrated second sorting and sorting station 23 comprises a near-infrared (NIR) spectroscopy system 222 and / or a visible spectroscopy system configured to distinguish the second type of plastic material from other types of mixed waste material in the material stream PS, and a discharge unit 224 configured to separate the second type of plastic material into the second plastic material fraction 3 from other types of material in the material stream PS (see also Figure 3). In other words, the second sorting and sorting station 23 distinguishes and separates plastic materials that differ from the first plastic material in either composition and / or color. Once the second type of plastic material is distinguished, it is separated into the second type of plastic material fraction 3 based on the information from the distinction. The second sorting and separating station 23 handles the mixed waste material stream PS in the same manner as the first sorting and separating station 22, except that the first type of plastic material has already been separated and the material to be separated and separated is the second type of plastic material.

[0064] The first classification and sorting device 20 further comprises a second food grade classification and sorting station 26 which includes a camera-based object recognition system 226 and a discharge unit 224. The second food grade classification and sorting station 26 receives a second type of plastic material fraction from the second classification and sorting station 23 and sorts the second plastic material fraction into food grade or non-food grade. This yields a second food grade plastic material 11.

[0065] As those skilled in the art will understand, if System 1 needs to sort a third type of food-grade plastic material, a third sorting and grading station, as well as a third food-grade sorting and grading station, may be added to System 1.

[0066] In the first sorting and sorting device 20, further sorting is achieved by a further sorting and sorting station 27 that receives the mixed waste material stream PS from the second sorting and sorting station 23. The further sorting and sorting station 27 comprises a near-infrared (NIR) spectroscopy system 222 and / or a visible spectroscopy system configured to distinguish further types of plastic materials from other types of mixed waste materials in the material stream PS, and a discharge unit 224 configured to separate further types of plastic materials into a further plastic material fraction from other types of materials in the material stream PS (see also Figure 3).

[0067] Even after all plastic materials that could potentially be food-grade plastic materials have been separated from the mixed waste material stream, valuable objects may still remain in the mixed waste material stream. Therefore, to further improve the efficiency of the method, there may be further distinction and separation steps to distinguish and separate additional valuable plastic materials, thereby providing an additional plastic material fraction.

[0068] The sorting and separation device 20 further comprises a further purification sorting and separation station 28. Since the further purification sorting and separation station 28 is the same type of station as the first sorting and separation station 22, the second sorting and separation station 23, and the further sorting and separation station 27, how the station functions will not be repeated.

[0069] A further purification, sorting, and separation station 28 is configured to separate further types of plastic materials and further purify the further types of plastic material fraction. In other words, the further purification, sorting, and separation station 28 is configured to separate other materials from the further types of plastic material fraction. These steps further increase the purity level of the further types of plastic material fraction, thereby providing a refined further plastic material fraction 4.

[0070] The sorting and separating device 20 further comprises a recovery sorting and separating station 24 of the same type as the other sorting and separating stations. The recovery sorting and separating station 24 receives a mixed waste material stream PS from a further sorting and separating station 27 and is configured to distinguish and separate a first type of plastic material, a second type of plastic material, and further types of plastic material so that these types of plastic material are reintroduced into the mixed waste material stream PS entering the first sorting and separating station 22. Material items of each type of plastic material may not be distinguished or separated when they should have been, i.e., in the early stages of the process, for various reasons. This may be due to material items being stacked or stuck together, preventing all materials from being distinguished, or it may be due to oversight in the sorting step. Therefore, the recycling level of this method is further improved by giving material items overlooked in the first distinguishing and separating step an additional opportunity to be distinguished and separated into the correct type of plastic material. This loop may continue until the material items are correctly sorted.

[0071] Where different equipment and stations handling the first type of food-grade plastic material fraction 2 and the second type of plastic material fraction 3 are described below, only the equipment and stations handling the first type of plastic material fraction 2 will be described. The second type of plastic material fraction 3 also passes through substantially the same types of equipment and stations. Figure 2 shows such equipment only for the second type of plastic material fraction 3. More specifically, the second material item size reduction device 30a, the second washing device 40a, and the second purification, sorting, and separation device 50a are schematically shown in Figure 2.

[0072] System 1 further comprises a material item size reduction device 30, a washing device 40, and a purification, classification, and sorting device 50.

[0073] The first type of plastic material fraction 2 is received by the material item size reduction device 30. In the material item size reduction device 30, the size of the material items in the first type of food-grade plastic material fraction 2 is reduced. The material items are then crushed to smaller sizes by the crusher 32 in the material item size reduction device 30. The material items may be crushed to a size where the maximum cross-sectional length can be at most 18 mm.

[0074] The first washing station 42 of the washing apparatus 40 receives a first type of food-grade plastic material fraction 2 from the material item size reduction apparatus 30. By crushing the material items, the material items are more exposed and therefore may become accessible for the washing process. Washing of the first type of food-grade plastic material fraction 2 may be in an alkaline washing process and / or a high-temperature washing process. The temperature and alkalinity of the washing process depend on the composition of the first type of food-grade plastic material fraction 2 and / or the type of material that needs to be removed from the first type of plastic material by washing. The washing process may be used to remove stickers, labels, etc., from the material items in the first type of food-grade plastic material fraction 2.

[0075] The washing apparatus 40 further comprises a density separation station 44. The density separation station 44 receives the first type of food-grade plastic material fraction 2 purified from the first washing station 42 and separates the material denser than water from the material less dense than water. The flotation separation process may be advantageous because it can separate lighter materials from denser materials, thereby further improving the purity level of the food-grade plastic material 10. Subjecting material items to the flotation separation process also provides an alternative method for sorting different types of materials. Some types of materials will flot or sink, thereby sorting the materials based on their density.

[0076] Wet material items from the washing station may tend to stick to each other or to other objects, which can make it more difficult to separate the correct material items. Therefore, a first drying station 46 is added to the washing apparatus 40 of System 1. The first drying station 46 dries the first type of food-grade plastic material fraction 2. Drying may be carried out using air circulation and / or high temperature or other known drying methods. The dried material items of the first type of food-grade plastic material fraction are then subjected to two sorting steps. The first sorting step is carried out in the first air sieve machine 48 of the washing apparatus 40, where air is used to separate lighter materials from denser materials by using compressed air to blow away the lighter materials. The first air sieve machine 48 receives the first type of food-grade plastic material fraction 2 from the first drying station 46. The second sorting step is performed in the first screener 49 of the washing device 40, which sorts the material items based on their cross-sectional size. The first screener 49 receives the first type of food-grade plastic material fraction 2 from the first wind sieve machine 48.

[0077] Following the washing process, the washed material items of the first type of food-grade plastic material fraction 2 are separated again, and the first type of food-grade plastic material is separated from other types of material. Other types of material may be materials separated from the first type of food-grade plastic material during the sizing process or washing process. The refining sorting and separation apparatus 50 includes a first refining sorting and separation station 52 configured to receive the washed first type of food-grade plastic material fraction 2 from the first washing apparatus 40. The first refining sorting and separation station 52 in Figure 1 is of the same type as the first sorting and separation station 22. For the sake of efficiency, how it works will not be repeated and the sorting and separation stations will be further described in relation to Figure 3. The main difference between the first sorting and separation station 22 and the refining sorting and separation station 52 is that the refining sorting and separation station 52 separates other types of material from the washed first type of plastic material fraction 2, thereby obtaining the refined food-grade plastic material 10'.

[0078] While plastic materials are used throughout the explanation, it should be noted that these plastic materials may be specific types such as high-impact polystyrene, food-grade plastics, or food-grade high-impact polystyrene. The systems described above will function similarly with these types of plastics as well.

[0079] Moving to Figure 3, a schematic perspective view of the classification and sorting station 700 is shown. The first classification and sorting station 22, the second classification and sorting station 23, the further classification and sorting station 27, the first food grade classification and sorting station 25, the second food grade classification and sorting station 26, the recovery classification and sorting station 24, the further purification classification and sorting station 28, and the first refining classification and sorting station 52 may all be of the same type as the classification and sorting station 700 described herein. Each of the stations may have one or more of the features described below. However, for the sake of brevity, the station 700 will be described below as the classification and sorting station 700.

[0080] Material pieces or material items 710 are supplied to the classification and sorting station 700. The material pieces 700 are transported through the detection zone 720. However, the material pieces 700 may be provided through the detection zone 720 by any preferred means or manually without technical means. A light source device 730 and an NIR spectrometer 222 are provided. The spectrometer 222 is adapted to receive and analyze light 732 reflected and / or scattered by the material pieces 710 in the detection zone 720 from the light source device 730. Thus, the NIR spectrometer 222 typically obtains the spectrum of the material pieces 710 from the stream of material being transported through the detection zone 720. The NIR spectrometer 222 of the classification and sorting station 700 is configured to distinguish a first type of plastic material from other materials, such as plastic material, based on the obtained spectrum. In other words, the NIR system 222 is typically configured to distinguish a particular type of plastic material from other types of materials based on its spectrum.

[0081] The sorting and separation station may further include an optical spectroscopy system 760 configured to acquire spectra of plastic materials originating from a material stream PS being transported through a detection zone 720. The discharge unit 224 of the sorting and separation station 700 may further be configured to separate the aforementioned types of plastic materials originating from the mixed waste material stream PS based on the acquired spectra, thereby separating the first type of plastic material fraction based on its color.

[0082] The optical spectroscopy system 760 may determine different colors of the plastic material being transported through the detection zone 720 based on the acquired spectrum. The advantage of determining the color of the plastic material is that the plastic material can be sorted into different fractions.

[0083] The sorting and separation station 700 may further include a laser triangulation system 740 configured to determine height information of material 710 being transported through a detection zone 720. The discharge unit 224 of at least one sorting and separation station may further be configured to separate the plastic material based on the determined height information.

[0084] The laser triangulation system 740 is typically configured to project a laser beam 742 toward the detection zone 720. The illustrated laser triangulation system 740 includes a camera-based sensor device 744 configured to receive and analyze light 746 reflected and / or scattered by material pieces 710 within the detection zone 720. By using the laser triangulation system 740, the sorting and separation station 700 may be able to detect plastic materials that are difficult to detect with the NIR spectroscopy system 222. An example of such plastic material may be black plastic material. By detecting height differences on the conveyor belt used to transport the materials to be sorted, the sorting and separation station may combine its height information with information obtained from the NIR spectroscopy system 222 to determine whether black plastic material or difficult-to-detect plastic material is present on the conveyor belt. Thus, further plastic material may be recycled.

[0085] The classification and sorting station 700 may further include a camera-based object recognition system 226 having a camera 750 configured to acquire images of plastic material originating from a material stream being transported through a detection zone 720. The classification and sorting station 700 may further include a tracer-based sorting (TBS) unit 226a configured to acquire images of plastic material originating from a material stream being transported through a detection zone 720, such plastic material including TBS markers. The illustrated camera-based object recognition system 226 and / or TBS unit 226a further include at least one processor (not shown) capable of comparing the acquired images and / or images with TBS markers to a database of food-grade objects to determine whether an object is food-grade.

[0086] As an addition or alternative, the TBS unit 226a may input the acquired image having a TBS into a TBS decoding processor to obtain a decoded TBS, thereby distinguishing whether one or more objects in the acquired image are food grade.

[0087] As an addition or alternative, the camera-based object recognition system 226 may input the acquired image and optionally decoded TBS into a machine learning model trained to identify food-grade objects in the input image, thereby distinguishing whether one or more objects in the acquired image are food-grade. The machine learning model takes action based on patterns and relationships it finds in the acquired image, as is known in the art. The machine learning model may typically be trained to recognize patterns and, based on its training, make predictions and decisions to identify food-grade objects. The model may typically be trained using a set of input data about food-grade objects and corresponding output data indicating whether an object is food-grade or not. Based on such data, the machine learning model may typically be trained to make decisions based on patterns, features, or similar things it finds in the acquired image. In other words, the machine learning model may determine whether an object is food-grade or not.

[0088] The classification and sorting station 700 may be equipped with an artificial neural network in combination with the camera 750. Such an artificial neural network may be configured to detect various properties of the plastic material being transported through the detection zone 720 based on images acquired by the camera 750 and optionally decoded TBS. In this case, the discharge unit 224 of the classification and sorting station 700 may further be configured to separate the plastic material being transported through the detection zone 720 based on the detected properties of the plastic material. In other words, the properties of the plastic material may be determined by the artificial neural network from images acquired by the camera 750. The properties may be shape, color, surface features, or anything in the appearance of the plastic material that can be determined and classified by the artificial neural network. By using the TBS unit 226a, the camera 750 can further determine whether an object is food grade using information from invisible or fluorescent markings, or other non-visible TBS markings. The camera 750 may provide the possibility of further sorting the material into different fractions. With the help of artificial neural networks, it may be possible to sort plastic materials with the same material composition into different fractions depending on their quality and origin.

[0089] The camera-based object recognition system 226 may have one camera to acquire all images, or multiple cameras to cover different areas or to detect different information from objects.

[0090] Now moving to Figure 4, a method 100 for obtaining food-grade plastic material 10 from a mixed waste material stream PS is described. Method 100 begins by distinguishing a first type of plastic material from other types of material in the material stream PS using a near-infrared spectroscopic system 222 and / or a visible spectroscopic system 110a.

[0091] Method 100 proceeds to separate the first type of plastic material from the other types of material in the material stream PS into a first plastic material fraction 2 110b, thereby separating the first type of plastic material from the material stream PS.

[0092] The method proceeds to distinguishing a first type of food-grade plastic material from other types of materials in the first plastic material fraction using a camera-based object recognition system 226 111a.

[0093] The method proceeds to separating a first type of food-grade plastic material from other types of material in the first plastic material fraction into a first food-grade plastic material fraction 2 111b, thereby separating other types of material from the first plastic material fraction and thereby obtaining a food-grade plastic material 10.

[0094] It should be noted that the steps or actions in Method 100 described above may be performed in any preferred order and therefore do not have to be in the order given above. Furthermore, one or more of the steps or actions may be performed in parallel. Also, it should be noted that the steps or actions may be performed by different equipment, at different times and / or at different locations. In other words, for example, the method may be performed in a distributed manner at multiple locations where different steps or actions are performed at different times. However, it is advantageous for the method to be performed at a single location in the order described above.

[0095] Moving on to Figure 5, Method 100 from Figure 4 is shown along with a set of alternative steps. The alternative steps may be added to Method 100 from Figure 4 individually or in any combination, depending on the requirements. Steps already described in relation to Figure 4 will not be described again for the sake of efficiency.

[0096] The method further comprises, prior to the distinguishing step 110a, step 170a of separating ferrous material from the mixed waste stream using a magnetic device 62; step 170b of separating non-ferrous material from the mixed waste stream using an eddy current separator 62b; step 180 of separating objects from the mixed waste stream with a maximum cross-sectional length exceeding 320 mm into a crusher stream using a wind sieve 66 and / or screen 64; and step 190 of crushing the objects in the crusher stream so that their maximum cross-sectional length is less than 320 mm, and then rejoining the objects into the mixed waste material stream PS.

[0097] Following the sorting step 110b, a step 112a is provided in which a second type of plastic material is distinguished from other types of material in the sorted material stream PS using a near-infrared spectroscopy system 222 and / or a visible spectroscopy system.

[0098] Method 100 proceeds to separate the second type of plastic material from the other types of material in the material stream PS into the second plastic material fraction 3 112b.

[0099] Method 100 proceeds to distinguish a second type of food-grade plastic material from other types of materials in the second plastic material fraction using a camera-based object recognition system 226 113a.

[0100] Method 100 proceeds to separate the second type of food-grade plastic material from other types of material in the second plastic material fraction into the second food-grade plastic material fraction 3 113b, thereby separating other types of material from the second plastic material fraction and thereby obtaining the second type of food-grade plastic material 11.

[0101] Following the sorting step 112b, a step 114a is provided in which a near-infrared spectroscopy system 222 and / or a visible spectroscopy system is used to distinguish further types of plastic materials from other types of materials in the material stream PS, from which the second type of plastic material has been sorted.

[0102] Method 100 proceeds to separate further types of plastic materials from other types of materials in the material stream into a further plastic material fraction 114b, thereby separating further types of plastic materials from the material stream PS.

[0103] Method 100 proceeds to distinguish further types of plastic materials from other types of materials in the further plastic material fraction using a near-infrared spectroscopic system 222 and / or a visible spectroscopic system 115a.

[0104] Method 100 proceeds to separate further types of plastic material into a further plastic material fraction 4 refined from other types of material in the material stream 115b, thereby separating other types of material from the further plastic material fraction.

[0105] Method 100 proceeds to distinguish the first type of plastic material and, if present, the second type of plastic material, from other types of materials in the material stream PS, or, if present, the second type of plastic material, from other types of materials in the material stream PS, using a near-infrared spectroscopic system 222 and / or a visible spectroscopic system 116a.

[0106] Method 100 proceeds to separate the first type of plastic material and, if present, the second type of plastic material, from the other types of material in the material stream into a recovered plastic material fraction that is rejoined with the mixed waste stream PS 116b. By rejoining the recovered material fraction with the initial mixed waste material stream, all types of plastic material can be transported on a single transport means, such as a single conveyor belt.

[0107] The following describes the different steps for processing the first type of food-grade plastic material fraction 2 and the second type of food-grade plastic material fraction 3. For efficiency, the steps are described together. However, it should be understood that these are two different flows, and these steps may be performed in parallel with each other and at different stations.

[0108] Method 100 proceeds to distinguish the first type of food-grade plastic material from the other types of materials in the first type of food-grade plastic material fraction 2 and the second type of food-grade plastic material fraction 3 using a near-infrared spectroscopic system 222 and / or a visible spectroscopic system 111a, 113a.

[0109] Method 100 proceeds to separate other types of materials from the first type of food-grade plastic material in the first type of food-grade plastic material fraction 2 and the second type of food-grade plastic material fraction 3, 111b, 113b, thereby purifying the first type of food-grade plastic material fraction 2 and the second type of food-grade plastic material fraction 3.

[0110] Method 100 proceeds to subject the first type of food-grade plastic material fraction 2 and the second type of food-grade plastic material fraction 3 to a flotation separation step 150, 152, thereby separating the material with a density higher than water from the material with a density lower than water.

[0111] The method proceeds to drying the materials in the first type of food-grade plastic material fraction 2 and the second type of food-grade plastic material fraction 3, 160, 162.

[0112] Method 100 proceeds to distinguish the first type of food-grade plastic material 2 and the second type of food-grade plastic material 3 from other types of material in the washed first type of food-grade plastic material fraction 2 and the second type of food-grade plastic material fraction 3 using a near-infrared spectroscopic system 222 and / or a visible spectroscopic system 140a, 142a.

[0113] Method 100 proceeds to separate the first type of food-grade plastic material 2 and the second type of food-grade plastic material 3 from other types of material in the washed first type of food-grade plastic material fraction 2 and the second type of food-grade plastic material fraction 3 140b, 142b, thereby separating other types of material from the washed first type of food-grade plastic material fraction 2 and the washed second type of food-grade plastic material fraction 3, thereby obtaining the purified food-grade plastic material 10' and the second purified food-grade plastic material 11', respectively.

[0114] It should be noted that the steps or actions in Method 100 described above may be performed in any preferred order and therefore do not have to be in the order given above. Furthermore, one or more of the steps or actions may be performed in parallel. Also, it should be noted that the steps or actions may be performed by different equipment, at different times and / or at different locations. In other words, for example, the method may be performed in a distributed manner at multiple locations where different steps or actions are performed at different times. However, it is advantageous for the method to be performed at a single location in the order described above.

[0115] Furthermore, by examining the drawings, disclosures, and accompanying claims, various modifications of the disclosed modifications can be understood and implemented by those skilled in the art when practicing the claimed invention. In the claims, the word “equipped with” does not exclude other elements, and the indefinite article “a” or “an” does not exclude plurals. The mere fact that certain means are described in different dependent claims does not imply that combinations of these means cannot be used advantageously.

Claims

1. A method (100) for obtaining food-grade plastic material (10) from a mixed waste material stream (PS), Distinguishing a first type of plastic material from other types of materials in the material stream (PS) using a near-infrared spectroscopy system (222) and / or a visible spectroscopy system (110a), The first type of plastic material is separated into a first plastic material fraction from other types of material in the material stream (PS) (110b), thereby selecting the first type of plastic material from the material stream (PS), Using a camera-based object recognition system (226), distinguish a first type of food-grade plastic material from other types of materials in the first plastic material fraction (111a), The first type of food-grade plastic material is separated from other types of material in the first plastic material fraction into a first food-grade plastic material fraction (2) (111b), thereby separating other types of material from the first plastic material fraction, thereby obtaining the food-grade plastic material (10). A method (100) comprising:

2. Using a near-infrared spectroscopy system (222) and / or a visible spectroscopy system, distinguish the second type of plastic material from other types of material in the material stream (PS) from which the first type of plastic material has been separated (112a), The second type of plastic material is separated into a second plastic material fraction from other types of material in the material stream (PS) (112b), thereby selecting the second type of plastic material from the material stream (PS), Using a camera-based object recognition system to distinguish a second type of food-grade plastic material from other types of materials in the second plastic material fraction (113a), The second type of food-grade plastic material is separated from other types of material in the second plastic material fraction into a second food-grade plastic material fraction (3) (113b), thereby separating other types of material from the second plastic material fraction, thereby obtaining the second type of food-grade plastic material (11). The method according to claim 1 (100), further comprising the above.

3. Using a near-infrared spectroscopy system (222) and / or a visible spectroscopy system, further types of plastic materials are separated from other types of materials in the material stream (PS) from which the second type of plastic material has been separated (114a), The further types of plastic materials are separated into a further plastic material fraction from other types of materials in the material stream (114b), thereby selecting the further types of plastic materials from the material stream. Distinguishing the further types of plastic materials from other types of materials in the further plastic material fraction using a near-infrared spectroscopy system (222) and / or a visible spectroscopy system (115a), The further types of plastic materials are separated into a further plastic material fraction (4) refined from other types of materials in the material stream (115b), thereby separating other types of materials from the further plastic material fraction. The method according to claim 2 (100), further comprising the above.

4. Reducing the size of the material items in the first type of food-grade plastic material fraction (2) (120), The first type of food-grade plastic material fraction (2) is subjected to an alkaline washing process and / or a high-temperature washing process (130), Using a near-infrared spectroscopy system (222) and / or a visible spectroscopy system, distinguish the first type of food-grade plastic material in the washed first type of food-grade plastic material fraction from other types of material (140a), The first type of food-grade plastic material in the washed first type of food-grade plastic material fraction is separated from other types of material (140b), thereby separating other types of material from the washed first type of food-grade plastic material fraction, thereby obtaining a refined food-grade plastic material (10'). If the second type of food-grade plastic material exists, Reducing the size of material items in the second type of food-grade plastic material fraction (3) (122), The second type of food-grade plastic material fraction (3) is subjected to an alkaline washing process and / or a high-temperature washing process (132), Distinguishing the second type of food-grade plastic material from other types of material in the washed second type of food-grade plastic material fraction using a near-infrared spectroscopy system (222) and / or a visible spectroscopy system (142a), The washed fraction of the second type of food-grade plastic material is separated from the other types of material (142b), thereby separating the other types of material from the washed fraction of the second type of food-grade plastic material, thereby obtaining a purified second type of food-grade plastic material (11'). The method according to any one of claims 1 to 3, further comprising (100).

5. After subjecting the first type of food-grade plastic material fraction (2) and, if present, the second type of food-grade plastic material fraction (3) to the washing step (130), Dry the material in the first type of food-grade plastic material fraction and, if present, the material in the second type of food-grade plastic material fraction (150, 152) The method according to claim 4 (100), further comprising the above.

6. After subjecting the first type of food-grade plastic material fraction (2) and, if present, the second type of food-grade plastic material fraction (3) to the washing step (130), The method according to claim 4 or 5 (100), further comprising subjecting the first type of food-grade plastic material fraction (2) and, if present, the second type of food-grade plastic material fraction (3) to a flotation separation step (160, 162), thereby separating a material denser than water from a material less dense than water.

7. The first type of plastic material is a first type of high-impact polystyrene material, and as a result, the food-grade plastic material (10) is a food-grade high-impact polystyrene material. If the second type of plastic material is present, The second type of plastic material is the second type of high-impact polystyrene material, and as a result, the second type of food-grade material (11) is the second food-grade high-impact polystyrene material. If the aforementioned further types of plastic materials exist, The method according to any one of claims 1 to 6 (100), wherein the further type of plastic material is a mixed high-impact polystyrene material.

8. The camera-based object recognition system (226) The camera (750) acquires images of objects in the first plastic material fraction (2) and, if present, in the second plastic material fraction (3), and The processor compares the acquired image with a database of food-grade objects to determine whether the object is food-grade. The method according to any one of claims 1 to 7, distinguished by (100).

9. The camera-based object recognition system (226) The camera (750) acquires images of objects in the first plastic material fraction (2) and, if present, in the second plastic material fraction (3), and The acquired image is input into a machine learning model trained to identify food-grade objects in an input image, thereby determining whether the object in the acquired image is of food grade. The method according to any one of claims 1 to 7, distinguished by (100).

10. The camera-based object recognition system (226) further comprises a tracer-based sorting (TBS) unit (226a), and the tracer-based sorting (TBS) unit (226a) The camera (750) is used to acquire an image of an object having a TBS marker in the first plastic material fraction (2) and, if present, in the second plastic material fraction (3). The processor detects the TBS marker in the acquired image, and The processor compares the detected TBS marker with a database of TBS markers to determine whether the object is of food grade. The method according to claim 8 or 9 (100), distinguished by...

11. Using a near-infrared spectroscopy system (222) and / or a visible spectroscopy system, distinguish the first type of plastic material and, if present, the second type of plastic material from other types of materials in the material stream (PS) from which the first type of plastic material has been separated, or, if present, the second type of plastic material from other types of materials in the material stream (PS) from which the second type of plastic material has been separated (116a), (116b) Separating the first type of plastic material and, if present, the second type of plastic material from other types of material in the material stream into a recovered plastic material fraction that is recombined with the mixed waste stream (PS) The method according to any one of claims 1 to 10, further comprising (100).

12. Before distinguishing the first type of plastic material (110a), Separating iron material from the mixed waste stream using a magnetic device (170a), and / or, Separating non-ferrous materials from the mixed waste stream using an eddy current separator (170b) The method according to any one of claims 1 to 11, further comprising (100).

13. Before distinguishing the first type of plastic material (110a), The method according to any one of claims 1 to 12 (100), further comprising separating objects from the mixed waste stream having a maximum cross-sectional length exceeding 320 mm into a crusher stream (180) using a wind sieve (66) and / or a screen (64).

14. The method according to claim 13 (100), further comprising crushing the object in the crusher stream so that the maximum cross-sectional length is less than 320 mm (190), and rejoining the object to the mixed waste material stream (PS).

15. A system (1) for obtaining food-grade plastic material (10) from a mixed waste material stream (PS), A first sorting and sorting station (22) configured to receive the mixed waste stream (PS), comprising: a near-infrared (NIR) spectroscopy system (222) and / or a visible spectroscopy system configured to distinguish a first type of plastic material from other types of material in the material stream (PS); and a discharge unit configured to separate the first type of plastic material from other types of material in the material stream (PS) into a first plastic material fraction, thereby separating the first type of plastic material from the material stream (PS), A first food grade sorting and sorting station (25) configured to receive the first plastic material fraction, comprising: a first camera-based object recognition system (226) configured to distinguish a first type of food grade plastic material from other types of plastic material in the first plastic material fraction; and a discharge unit configured to separate the first type of food grade plastic material from other types of plastic material in the first plastic material fraction into a first food grade plastic material fraction (2), thereby separating other types of material from the first plastic material fraction, thereby obtaining the food grade plastic material (10) from the material stream (PS). A system (1) comprising:

Images