EP3047258A1

EP3047258A1 - Device for automatically identifying fluorescence of tracers with a view to automatically sorting and/or controlling the quality of marked products or materials, which may or may not be coloured

Info

Publication number: EP3047258A1
Application number: EP14786224.7A
Authority: EP
Inventors: Elisabeth Maris; Daniel Froelich; Claude Paul LAMBERT; Jean-Michel Hachin
Original assignee: Tracing Technologies; ARTS
Current assignee: Tracing Technologies; ARTS
Priority date: 2013-09-16
Filing date: 2014-09-16
Publication date: 2016-07-27
Also published as: WO2015036719A1; FR3010789A3; FR3010790B1; FR3010790A1

Abstract

The invention relates to a device (1) for identifying and/or authenticating a material (2) or an object, in particular for sorting dark or black plastic materials containing chemical tracers at concentrations of less than 50 ppm, comprising: - a source (3) of UV or IR excitation radiation (4); - a detector (6) for detecting fluorescence emitted by the material (2) subjected to said radiation; - processing means (8) for detecting and identifying the tracers. The invention also relates to a method for using such a device.

Description

DEVICE FOR AUTOMATICALLY IDENTIFYING FLUORESCENCE OF PLOTTERS FOR THE AUTOMATIC SORTING AND / OR QUALITY CONTROL OF COLORED OR NON-COLORED PRODUCTS OR MATERIALS

The present invention relates to a device and a method for high speed identification of objects, particles or materials, automatically, without contact. It relates in particular to such a device or such a method coupled to a device or a sorting method (positive sorting or negative ejection) or likely to create an alert (control-quality).

The present invention is particularly applicable to the sorting and recycling of materials from used objects.

The concept of tracing system of virgin polymers for sorting developed from the years 1993. The first patent filed [British Petroleum Company, 1993] describes a method of identifying polymers by fluorescence detection of certain tracers based of rare earths in the near infrared (NIR) spectral range between 700 and 900 nm for tracer concentrations of 0.00 lppm to lppm. The source used is a laser diode that emits in the NIR at 670nm. The disadvantage of this method is the difficulty of detecting a signal in NIR when the matrix is dark. The carbon black used as a dye absorbs all radiation in the NIR [Eisenreich, 1992].

A patent filed in 1994 [Bayer, 1994] describes two tracer systems having different fluorescence emission wavelengths and for each system of tracers having different fluorescence durations. The identification principle allows coding with four tracers. This method is currently used in the field of biochemistry, the experimental system includes a flash lamp and a programmable camera to postpone the triggering of the image taking a few nano seconds after excitation by the source. This system therefore makes it possible to identify molecules that have the same fluorescence emission wavelength but not the same duration. This method seems difficult to set up at the level of rapid and automated sorting because in the case of industrial systems the samples to be sorted are lit continuously and it is impossible to differentiate tracers.

In 1998 another study funded [Simmons et al., 98] [Ahmad, 2000] by a European program resulted in a first pilot for a sorting application of plastic bottles in the packaging sector. The system allowed, from a coding based on combinations of three tracers at concentrations between 0.5 and 20 ppm, to identify bottle packs made of HDPE. Patents on the identification system have been filed [Lambert, 2004]. The pilot bench did not identify dark colored polymers and no testing was done on other types of polymer matrices.

In 2005 a patent [ERIEZ, 2005] was filed on the magnetic sorting of polymers containing magnetic tracers. In 2007, a tracer study validated the automated rapid sorting of black ground polypropylene [Froelich, 2007]. In the same study, a state of the art was carried out on the various tracing technologies [Froelich, 2007]. Two technologies have been validated for the sorting of black polypropylene: the detection of magnetic tracers and the detection in X rays fluorescence of tracers based on rare earths. In 2008, a thesis was funded by the ADEME (Agency for the Development and Control of Energy) to perform laboratory tests for X-ray fluorescence detection [Bezati et al, 2010]. The results of these Work shows that detection by magnetic tracers is industrially viable but does not allow coding with multiple tracers. X-ray fluorescence detection can detect rare earth oxide tracers at concentrations of 1000 ppm in black or painted color polymers. The absorption of X-ray fluorescence by the molecules of the ambient air does not make it possible to reduce the tracer concentrations to less than 100 ppm and the detection times are still long compared to the industrial fast sorting constraints. The choice of tracers is limited to rare earths.

These different patents and studies have all validated the technique of tracing polymers but these technologies are not suitable for dark colored materials, they are also not adapted to industrial constraints, including fast sorting in 10 ms.

A patent was published under the number FR 2 934 510 [Lambert, 2010] on the concept of tracing polymers for recycling and counterfeiting.

Recycling materials from end-of-life products is essential to preserve our non-renewable resources and reduce our impacts on climate change, human health impacts and ecosystems. Several obstacles to the recycling of materials exist, technical brakes and brakes related to the social acceptability of recycled materials.

There are still several technical barriers to recycling materials from end-of-life products. These products are collected and treated at the end of their life, this leads after grinding to sorting complex mixtures [Reuter, 2005] which at the beginning at the level of a product could be eco-designed. Another obstacle is related to the two types of industrial sorting technologies most representative of the recycling sector that do not allow to sort materials by physicochemical sorting such as densimetric sorting when densities overlap and NIR fast spectrometric sorting when the polymers are dark in color.

In 2009, 24.3 million tonnes of plastic waste were generated in Europe and only 22.5% on average were recycled across all sectors (PlasticsEurope, 2010).

The barriers to social acceptability lie in the traceability of toxic substances potentially contained in recycled materials and waste that is found in the seas because they are not recycled. A proposal is therefore to add a new property specific to the material (signature, marking) that can be detected in order to identify the material with an automated rapid industrial sorting machine. Tracer / polymer systems were developed from laboratory tests, detection tests were performed to detect the signals of these systems.

The invention therefore more particularly aims to solve to allow a high-speed identification of objects or materials, including dark matter, particularly for sorting for the recycling of plastics.

This involves developing a detection device allowing identification of light and dark colored polymeric materials containing low concentrations of tracers. These concentrations are preferably less than 1000 ppm and should be detected in black materials. The concentrations are preferably from 0.1 ppm to 1000 ppm. Low concentrations do not alter the properties of the plotted materials, are less expensive and difficult to counterfeit.

Preferably, such a device must meet the following requirements: - fast response, so automatic;

- be able to be coupled or integrated with an automatic sorting device or warning device, in the QC of quality controls;

- without contact and at a distance, for example at 30cm;

- little or no moving part;

- little sensitivity to the environment, for example dust; or transport medium, for example a carpet;

programmable, in particular according to the matrices, the tracers, the positive or negative choice, the new formulations, nature of the feeds, and adjustable according to the purity or the desired grade, in particular the setting of a confidence interval;

- lifetime of several thousand hours, hence the important choice of the source of excitation;

- even sensitive to very weak signals: detection of tracers even at very low concentrations;

signal processing enabling the identification of tracers in matrices that are not only colored but also black;

- ability to identify not only packaging type objects but also having small areas such as chips, particles or powders.

According to a first object of the invention, a device for the identification and / or authentication of a substance or an object, in particular with a view to sorting materials or articles containing one or more chemical tracers in low amount, ie concentrations below 50 ppm, includes:

a source for emitting ultraviolet or infrared excitation radiation towards the material;

a detector for a fluorescence signal emitted by the material subjected to the radiation; - Processing means for an electrical signal representing the fluorescence signal for detecting and identifying the tracer or tracers, then issue a response.

Such a device may further comprise:

- A conveyor to move the material vis-à-vis the source and the detector; and,

means for sorting the material according to the response.

The source may be a laser, whose beam is sent back to the conveyor by means of a parabolic angled mirror so that the laser beam scans a section of the conveyor. It can be designed to emit in the ultraviolet domain, for Stokes tracers, or infrared for Trace Stokes tracers. Advantageously, this source is designed to emit successive flashes.

The sorting means comprise ejection means, preferably by blowing.

The detector can be provided to detect in the visible or ultraviolet or infrared. It may advantageously comprise a collimation system with short focal length, preferably 30mm neighbor and a diameter of 25mm. The collimation system can be connected to a spectrometer by means of an optical fiber.

Advantageously, a device according to the invention comprises several detection means, and preferably several sources, along a path of the material in this device.

According to a second object of the invention, a method for the identification and / or authentication of a material or an object, particularly with a view to sorting materials or objects containing one or more chemical tracers in small quantities, ie concentrations of less than 50 ppm, uses a device according to the invention.

Such a method preferably uses tracers having excitation wavelengths between 280 and 400 nm or 870 to 1100 nanometers, preferably between 970 and 1100 nm. Advantageously, each tracer is chosen so that the lifetime of its fluorescence is greater than that of the matrix of the material or of the object.

The concentration of each tracer can be chosen to have a signal on noise allowing detection with a confidence interval of preferably 95%.

The speed of movement of the material or the object in front of the detector is advantageously between 1m / s and 5m / s, preferably close to 3m / s.

In such a method, the method of calculating the fluorescence indices is preferably used to determine the presence of the tracer (s).

Such a method is advantageously used when the material is highly absorbent, dark, strongly colored or black.

The invention also relates to a process for sorting and recycling plastics using a method according to the second subject of the invention, in which the materials are reduced into pieces whose size is between 5 mm and 200 mm, preferably in particles whose size is between 30 and 60 mm. The invention also relates to an authentication method using a method according to the second subject of the invention.

Several embodiments of the invention will be described below, by way of non-limiting examples, with reference to the appended drawings in which:

- Figure 1 schematically illustrates a configuration of a device according to the invention, adapted to the rapid detection of tracers;

- Figure 2 schematically illustrates another configuration of a device according to the invention adapted to the rapid detection of tracers on a conveyor;

FIG. 3 is a graph illustrating results of a test for determining the fluorescence signal intensity as a function of the angle of the laser relative to the normal to the conveyor;

FIG. 4 is a graph illustrating results of a test for determining the fluorescence signal intensity as a function of the collimator angle with respect to the normal to the conveyor;

FIG. 5 is a graph illustrating results of a test for determining the fluorescence intensity of crushed plastics as a function of their size;

FIG. 6 is a graph illustrating peaks of intensity at specific frequencies of tracers;

FIG. 7 is a graph illustrating the determination of the decision threshold and the limit of detection by a predictive approach;

FIG. 8 is a graph illustrating the spectra of tracers and a conveyor belt; and,

FIG. 9 is a graph illustrating the tracer indices and the detection thresholds.

FIG. 1 illustrates a device 1 making it possible to identify material 2 at high speed, which may take the form of objects or particles, for example thanks to the detection of a tracer signature. In the example illustrated, tracers were mixed with the material 2.

The detection device 1 comprises:

a source 3 for emitting ultraviolet (UV) or infrared (IR) excitation radiation 4 towards material 2;

a detector for a fluorescence signal 7 emitted by the material 2 subjected to radiation;

processing means 8 for an electrical signal 9 representing the fluorescence signal 7 making it possible to detect and identify the tracer (s), then to issue a response 10.

In the example illustrated, the device 1 further comprises:

- A conveyor 11 for moving the material 2 vis-à-vis the source 3 and the detector 6; and,

means 12 for sorting the material 2 as a function of the response 10.

In the illustrated example, the sorting means comprise an ejection system, for example by blow guns.

In the illustrated example, the material has the form of crushed plastic particles. The speed V of the particles traveling on the conveyor is between 1 and 5 m / s and preferably 3m / s.

Tracer excitation is for example in the field of ultraviolet (stokes tracers) or infrared (anti-stokes tracer) and the detection of the polymer-tracer system is for example in the visible, in UV or infrared. This configuration is very favorable for light or dark colored plastics. The acquisition time is between 1 and 10 ms minimum. The excitation wavelengths of the tracers will be included for PUV between 280 and 400 nm but may be extended to other wavelengths. For IR excitation, the lengths may range from 870 to 1100 nanometers, preferably from 970 to 1100 nm. The fluorescence lifetime of the tracers must be compatible with the speed of the particles of traced materials that run on the conveyor.

The device 1 allows a high-speed automated sorting reading of particles composed of a material added with fluorescent tracers. The detected signal 7 for identifying the traced materials is a fluorescence intensity at specific wavelengths of the tracers.

The choice of the tracers and their concentration are dependent on the detection system, the fluorescence of the polymers constituting the material 2 and the fluorescence lifetime of the tracers, the size of the particles of material and their speed on the conveyor.

The approach adopted for the choice of tracers and their concentration is:

1. to analyze the fluorescence of the materials to be traced;

2. determine an excitation and emission window where the fluorescence of the materials is low;

3. choose a tracer adapted to the existing reading material and materials on the market;

4. calculate the tracer concentration to have a signal on noise allowing a high speed detection with a confidence interval of preferably 95%; and,

5. Choose a detection window favorable to the detection of tracers incorporated into the materials.

Polymeric materials have a greater or lesser degree of fluorescence depending on the excitation and emission wavelengths. To detect a tracer in low concentration, it is interesting to have a high signal-to-noise ratio, the noise being due to the materials must be low as well as that of the reading system, so that the noise signal of the tracer is detectable with a confidence interval compatible with industrial sorting. This range is preferably greater than 95%.

The configuration of the reading system adapts to an industrial conveyor for the automated sorting of plastic waste either on a conveyor or in free fall and the size of the particles of crushed material. The particle size of the particles may be between 5 mm and 200 mm but preferably between 30 and 60 mm for a particle speed preferably equal to or close to 3 m / s.

The sources 3, poly chromatic or monochromatic, can be:

- for UV: lasers, laser diodes, LEDs, gas tubes such as, for example, xenon lamp or mercury lamp, operating in pulsed or continuous mode, with or without a reflector, condenser, provided with or without filters for example interferential to select good excitation wavelengths of the tracers and provided with or without optical fiber to transport the radiation; and,

- For IR: lasers, laser diodes, LEDs, lamps such as filament lamps, operating in pulsed or continuous mode, with or without a reflector, condenser, with or without filters, for example interferential to select good excitation wavelengths of the tracers and provided with or without optical fiber to carry the radiation.

The detector 6 of the fluorescence signals 7 comprises:

A collector for fluorescence photons emitted by the tracers;

The collection of photons is, for example, using an objective facing the conveyor belt. This goal collects and concentrates the light 7 emitted by one or more particles at the detector input. Optical fibers can be used to collect and transport the fluorescence signals emitted by a particle to the detector (single fiber), or even the fluorescence signals emitted by several particles to the detector or detectors (multi-stranded fiber).

- A spectrometer, which makes it possible to determine the wavelengths of the fluorescence signals of the tracers. It may consist of a rapid spectrometer from the trade or optimally designed from different elements such as:

• an entrance slot, a calibrated hole or a row of small diameter fibers;

A dispersive system for the wavelengths of the Diffraction grating, prism or Perot-Fabry type of device, selected interference filters for the fluorescence wavelengths of the tracers;

• optical collimation and concentration of beams;

• Sensors of high sensitivity such as photodiode arrays (avalanche or not), CCD, EMCD or CMOS sensors, linear or two-dimensional, cooled or not, integrating or not selective filters (Bayer matrix, IR filter, L filter RGB,), microlens arrays, ... Linear CCDs are faster and can detect at integration times of 1ms. The data transfer times are generally 2μ8.

A detector may also comprise photomultiplier tubes, avalanche photodiodes or any device capable of detecting and / or amplifying light signals of low intensities, equipped with Perot-Fabry type devices, selected interference filters for wavelengths. fluorescence tracers. FIG. 2 also illustrates, by way of example, a hardware configuration adapted to the rapid detection of tracers on a conveyor 11.

In this example, the beam 4 of a laser 3 is returned to the conveyor 11 by means of a bent mirror 14 of parabolic shape and the laser signal scans a section of the conveyor.

The fluorescence detection is in the visible but can be extended in the field of UV and Infrared. The detector 6 comprises a collimation system 15 with short focal length, for example 30 mm, and a diameter of 25 mm, for example. The collimation system 15 is at a height H15 of 20 cm with respect to the conveyor 11. This optical part 1 is connected to a spectrometer 16 thanks to an optical fiber 17.

Advantageously, such a system is repeated along the conveyor, for example every 10 cm. This repetition makes it possible to optimize the detection of numerous plastic particles that run on a conveyor, which may have a length of 50 or 100 cm, for example.

Tests were carried out with a UV laser, Kimmon Model IK Series HeCd, an interference filter passing a specific excitation wavelength to the signature of the tracers. An optical ocean type spectrometer of type QE65000 or HR2000 + was used. The signal was detected using signal processing software.

As illustrated in FIGS. 3 and 4, the configuration of the device 1 is optimal, that is to say that the signal losses are less than 10%, if the incident beam 4 of the laser 3 or the collimation system makes an angle with the normal to the lower carpet at 30 °. The crushed plastics generally have different thicknesses, for example between 1 mm and 4 mm thick, a variation of 3 mm. As illustrated in FIG. 5, the short focal length of the collimation system 15 makes it possible to detect a variation in 3mm with a signal loss of less than 10%.

Other tests were made to determine the fluorescence intensity of crushed plastics as a function of time. Depending on the surface of the crushed plastics and the conveyor running time particles containing tracers can be detected. As illustrated in FIG. 6, each wavelength corresponding to a tracer is illustrated by a peak 21. The wavelength corresponding to a fluorescence specific to each tracer, represented by a peak 21, serves as a signature for the plastic. This wavelength is indicated in a software equipping the processing means 8 as well as the wavelength interval to be taken into account in calculating the area of each peak 21. A black is made to subtract the noises parasites due to any light pollution, a blank is made to subtract the noise due to the polymer matrix.

The conveyor belt should preferably be made of a material that does not have wavelength fluorescence for the detection of tracers and preferably plastics containing as much carbon black as possible or halogenated substances that absorb the fluorescence of the plastic carpet so as not to emit parasitic fluorescence. Residual fluorescence from the carpet can then be recorded and subtracted from the tracer signal.

Polymers, a component of the plastics material 2, are organic materials and have a high fluorescence which can hinder the detection of low tracer concentrations. A favorable zone must therefore be determined. The excitation zone favorable to the detection of tracers is preferably less than 350 nm. Beyond the polymers have a high fluorescence in the visible and infrared. The detection zone favorable to fluorescence detection is preferably in the visible range between 400 nm and 750 nm. In fact, the fluorescence of the polymers is high.

An indicator is calculated. If its value reaches a threshold defined by preliminary tests for a confidence interval greater than 95%, then the signal is positive and the tracer is detected and the material identified. The threshold is determined by detecting the signal of materials without tracer and that of materials with tracer. The indicator may be the ratio of the peak area to an area corresponding to a non-tracer area. The advantage of the ratio method is to ignore the intensity of a signal that varies with the color of the material. Calculating a ratio is equivalent to normalizing all spectra.

Tests were carried out with 40mmx40mm particles with and without tracer. The tracer has a peak between the wavelengths of 624 and 629nm, an indicator is calculated by making the ratio between the peak area and the area of a fluorescence zone of the stable and weak matrix. The threshold is 0.1 and corresponds to the brait. Only the plastics signals containing the tracer are detected with an indicator greater than 0.1 (see Figure 6). The value of the indicator may depend on the size and the manner in which the particle appears in front of the detector for a speed of 3m / s.

Preferably, the source 3 emits the radiation 4 in the form of successive flashes. When the tracer or tracers are suitably chosen so that their fluorescence has a longer life than that of the matrix of material 2 in which they are included, between two flashes, a measurement of a persistent fluorescence is carried out. This fluorescence then corresponds more to that of the tracer or, as the matrix or, of shorter duration, decreases. Advantageously, when the device 1 is used to sort particles of matter, the flashes are emitted at a rate large enough that several measurements can be made on the same particle of matter 2; the risk of error related to the identification of each material is all the more negligible as the number of measurements made on the same particle is large.

The detection method will now be described in more detail with reference to FIGS. 7 to 9.

In the case of industrial sorting, the polymers have different hues. As the intensity of the fluorescence peaks varies according to the carbon black content, the intensities are variable. In this case, the shape of the peak is a characteristic allowing its detection. It is therefore necessary to use a form recognition method (it is then necessary to build a library) or to use the index calculation method.

The fluorescence index calculation method, which is an intensity ratio (Perrette et al., 2004, Poulenard et al., 2008) makes it possible to calculate a relative value of the intensity with respect to the fluorescence intensity of the polymers which is stable. This method amounts to normalizing the spectra and calculating a decision threshold.

The decision threshold is the critical value yc (see Figure 7) for which the probability of obtaining a measurement value greater than this value is equal to the risk. Risk a is the probability of having a false positive and the risk β of having a false negative (PJVIER et al., 2004). If the distribution of the population of measures follows a normal distribution (normal law table) for a risk of 2 = 0.05, ie a confidence interval of 0.95, the numerical factor is: z = 1.96.

To identify a polymer from the tracer (s) fluorescence signal, an index is calculated as well as a threshold from which the tracer signal is identified. The index may be a ratio of peak intensity, peak integral, value of first or second derivatives, sum of ratios of several indexes characterizing different bandwidths of the spectrum. For example, the index Indl is the ratio between the value of the integral of the intensity peaks of the tracers and the value of the integral of a zone of the spectrum where there is no fluorescence of the tracers. We then have:

For three tracers named Tl, T3 and T10, the wavelength ranges for Ind] are given in the table below.

The calculation of an index corresponding to the ratio of the intensities has not been retained because it is less reliable for the tracer T1 since we obtain numerator values that are sometimes negative (because of the fluorescence of the carpet) and with relative standard deviations. taller. The advantage of this index is to discriminate tracers with nearby peaks.

The values of the index of the plotted polymer and the index of the same polymer not plotted are calculated from the measurements. The IndTl index is the average of the measured values for the samples containing a tracer minus twice the standard deviation on the measurements (risk β = 0.25, z = l, 96). The index Indl is the average of the values of the blank (polymer not plotted) plus twice the standard deviation (risk a = 0.25). IndTl must be greater than Indl for particle concentration and particle velocity to be validated. Figure 8 illustrates the intensities recorded at different wavelengths.

The carpet, black in color, has a fluorescence emission in the zone [430; 650] nanometers. Its peak of fluorescence is slightly lower than that of tracer T1 in static for the concentration of 300 ppm. The tracers T3 and T10 are perfectly discriminated at the respective concentrations of 30 and 100 ppm. Without the fluorescence of the carpet, the tracer T1 could be perfectly discriminated.

As illustrated in FIG. 9, the indexes of the tracers T1, T3 and T10, in dynamics, are v = 3m / s, and the detection thresholds.

The tracers T3 and T10 are perfectly discriminated except Tl whose index value is almost equal to that of the polymer without tracer (see table below). At v = 1m / s, T1 is perfectly discriminated, the index of the tracer is much higher than that of the polymer (T0 in the graph of FIG. 9).

The table below shows the indexes at speed V = 3 m / s.

IndTj Indj IndT ₃ Ind ₃ IndT ₁₀ Ind ₁₀ mean 9.96 8.06 3.14 0.38 1.61 0.47 standard deviation 0.56 0.24 0.22 0.01 0.07 0.02 deviation relative type 6% 3% 7% 4% 5% 4%

Critical risk index 8.90 8.53 2.73 0.41 1.47 0.51 = β = 0.25

Of course, the invention is not limited to the examples which have just been described.

Thus, the detection of the polymer-tracer systems, constituents of this material, can also be done in free fall; in this case, the collimation system is located below the conveyor and before the blow guns. In addition, a device according to the invention is not limited to sorting materials for recycling. It can also be used to authenticate an object. By way of example, such an object may be a bottle of wine equipped with an identifier, for example a capsule or a label. This identifier advantageously comprises one or more tracers making it possible to recognize the identifier and, consequently, to authenticate the bottle and the wine that it can contain.

The invention is also perfectly adapted to the control of the quality of raw materials before being put into production. For example, plastic pellets may be tracer added by their supplier; the invention makes it possible to control that the granules thus supplied are, each, those which must be used for the manufacture of a plastic object.

Claims

claims

1. Device (1) for the identification and / or authentication of a material (2) or an object, in particular for sorting materials or objects containing one or more chemical tracers in small quantities , ie concentrations of less than 50 ppm, characterized in that it comprises:

a source (3) for emitting ultraviolet (UV) or infrared (I) excitation radiation (4) towards the material (2);

a detector (6) for a fluorescence signal (7) emitted by the material

(2) subject to said radiation;

- Processing means (8) for an electrical signal (9) representing said fluorescence signal (7) for detecting and identifying the tracer (s), then emitting a response (10).

2. Device (1) according to claim 1, characterized in that it further comprises:

- A conveyor (11) for moving the material (2) vis-à-vis the source

(3) and the detector (6); and,

means (12) for sorting the material (2) according to the response (10).

3. Device (1) according to claim 2, characterized in that the source (3) is a laser, the beam (4) is returned to the conveyor (11) through a bent mirror (14) parabolic form of so that the beam of said laser scans a section of the conveyor.

4. Device (1) according to one of claims 2 and 3, characterized in that the sorting means comprise ejection means, preferably by blowing.

5. Device (1) according to one of claims 1 to 4, characterized in that the source emits in the field of ultraviolet, for tracers of Stokes type, or infrared for tracers type Anti-Stokes Tracer.

6. Device (1) according to one of claims 1 to 5, characterized in that the source is provided to emit successive flashes.

7. Device (1) according to one of claims 1 to 6, characterized in that the detector is provided to detect in the visible or ultraviolet or infrared.

8. Device (1) according to one of claims 1 to 7, characterized in that the detector (6) comprises a collimation system (15) short focal length, preferably 30mm neighbor and a diameter of 25mm.

9. Device (1) according to claim 8, characterized in that the collimation system is connected to a spectrometer (16) by means of an optical fiber (17).

10. Device (1) according to one of claims 1 to 6, characterized in that it comprises a plurality of detection means, and preferably several sources, along a path of the material in said device.

11. A method for identifying and / or authenticating a material (2) or an object, in particular for sorting materials or objects containing one or more chemical tracers in a small quantity, or concentrations below 50 ppm, characterized in that it uses a device according to one of claims 1 to 10.

12. The method of claim 11, characterized in that the tracer or tracers have excitation wavelengths between 280 and 400 nm or 870 to 1100 nanometers, preferably between 970 and 1100 nm.

13. The method of claim 11 or 12, characterized in that each tracer is chosen so that the lifetime of its fluorescence is greater than that of the matrix of the material or object.

14. Method according to one of claims 11 to 13, characterized in that the concentration of each tracer is chosen to have a signal on noise for detection with a confidence interval of preferably 95%.

15. Method according to one of claims 11 to 14, characterized in that the speed of movement of the material or the object in front of the detector is between 1m / s and 5m / s, preferably close to 3m / s. s.

16. Method according to one of claims 11 to 15, characterized in that the method of calculating the fluorescence index to determine the presence of the tracer or tracers.

17. Method according to one of claims 1 1 to 16, characterized in that it is used for a highly absorbent material, dark, strongly colored or black.

18. Process for sorting and recycling plastics according to one of claims 11 to 17, characterized in that said materials are reduced into pieces whose size is between 5 mm and 200 mm, preferably in particles whose size is between 30 and 60 mm.

19. Authentication method, characterized in that it comprises a method according to one of claims 1 to 17.