Methods for recycling LED components from waste lamp mixtures

Abstract

Method for recycling LED components from a mixture of waste lamps, in which a) a mixture of old lamps is fed into an irradiation chamber, b) the waste lamp mixture is irradiated with a radiation source emitting in the wavelength range of 400 to 500 nm, whereby the LED lamps excited to fluorescence by the irradiation emit fluorescent radiation, c) the emitted fluorescence radiation is detected with a detector and the LED lamps are thus identified, d) the identified LED lamps are separated from the remaining mixture of old lamps, e) the separated LED lamps are subjected to mechanical crushing, f) the crushed LED lamps consisting of LED components and non-LED components are irradiated with a radiation source emitting in the wavelength range of 400 to 500 nm, wherein the LED components excited to fluorescence by the irradiation emit fluorescent radiation, g) the emitted fluorescence radiation is detected with a detector and thus the LED components are identified and h) the identified LED components are separated from the non-LED components.

Description

[0001] The present invention relates to a method for recycling LED components from waste lamp mixtures, in which the LED lamps are located in a waste lamp mixture by means of a detector and subsequently separated from the remaining waste lamp mixture. This is followed by mechanical shredding of the LED lamps with subsequent detection and separation of the LED components from the non-LED components. According to the invention, a device for carrying out this method is also provided. The device is used in particular for separating light-emitting diodes and / or fluorescent lamps from a waste lamp mixture.

[0002] The material recycling of used lamps has become increasingly important in recent years. Currently, in collection group 4, both LED lamps and gas discharge lamps (also known as energy-saving lamps) are collected together. Gas discharge lamps contain mercury, while LED lamps are mercury-free. For efficient recycling, gas discharge lamps and LED lamps require different processes. To date, no automated separation method exists, as the necessary identification system is lacking.

[0003] The ILLUMINATE project (Automated Sorting and Recycling of Waste Lamps) was carried out within the framework of the EU's 7th Framework Programme. This project included the development of a multi-sensor system for detecting and separating different types of lamps, enabling the identification of lamp weights, shapes, and colors (http: / / cordis.europa.eu / result / rcn / 202758_en.html). However, the multi-sensor system is complex and requires knowledge of the products found or expected in the waste.

[0004] No other solutions for lamp sorting with a focus on LED lamp identification currently exist. Furthermore, a recycling process for LEDs would require the separation of the LED chips (or LED packages), for which suitable sensors are also currently unavailable.

[0005] Based on this, the object of the present invention was to provide a method and a device that makes it possible to achieve an efficient separation of waste lamp mixtures in an easy-to-handle manner.

[0006] This problem is solved by the method with the features of claim 8 and the apparatus with the features of claim 8. The further dependent claims describe advantageous embodiments. Claim 15 describes a use according to the invention.

[0007] According to the invention, a method for recycling LED components from waste lamp mixtures is provided, in which a) a mixture of old lamps is fed into an irradiation chamber, b) the waste lamp mixture is irradiated with a radiation source emitting in the wavelength range of 400 to 500 nm, whereby the LED lamps excited to fluorescence by the irradiation emit fluorescent radiation, c) the emitted fluorescence radiation is detected with a detector and the LED lamps are thus identified, d) the identified LED lamps are separated from the remaining mixture of old lamps, e) the LED lamps are subjected to mechanical shredding into LED components and non-LED components, f) the LED components are irradiated with a radiation source emitting in the wavelength range of 400 to 500 nm, wherein the LED components excited to fluorescence by the irradiation emit fluorescent radiation, g) the emitted fluorescence radiation is detected with a detector and thus the LED components are identified and h) the identified LED lamps are separated from the non-LED components.

[0008] The aforementioned mixtures of used lamps typically contain gas discharge lamps and LED lamps when collected properly in accordance with the German Electrical and Electronic Equipment Act (ElektroG). Gas discharge lamps come in various forms. A distinction is made between special designs and standard tube-shaped lamps. Similarly, LED lamps also come in special designs and standard tube-shaped lamps. Improper collection practices can lead to the inclusion of incorrectly sorted items such as incandescent and halogen lamps alongside LED and gas discharge lamps.

[0009] The inventive method enables the detection and separation of LED lamps from the waste lamp mixture. This allows the waste lamp mixture, which typically arrives at recycling companies as a mixed container of gas discharge lamps and LED lamps, to be pre-separated, so that both lamp types can subsequently be subjected to their own adapted and optimized recycling processes. According to the invention, after mechanical comminution into LED components and other components free of LEDs (non-LED components), the LED lamps are detected and identified using fluorescence radiation and then separated from each other. In this way, a fraction of LED components, e.g., LED chips, can be separated from the waste lamp mixture.

[0010] The majority of LED lamps used in lighting are based on a blue LED combined with a phosphor layer. This phosphor layer can be excited with blue light, resulting in luminescence in the green, yellow, and / or red spectral range. This allows the phosphors, and thus the LED chips / lamps, to be identified. This effect can be used to detect and separate LED lamps from the mix of waste lamps. The same method is therefore also suitable for identifying individual LED components, for example, after the lamps have been shredded during the recycling process to separate them into their individual components.

[0011] In contrast, phosphors used in discharge lamps can, with few exceptions, only be excited by UV or higher-energy radiation.

[0012] The invention offers the following advantages: • Savings in time and personnel during the pre-sorting of old lamps, • Increased safety against incorrect disposal, especially of mercury-containing lamps in the mercury-free fraction, • First-ever possibility to automatically detect LED chips in mixtures with other fractions of shredded lamp or electronic waste.

[0013] The separation of the identified LED lamps from the remaining waste lamp mixture is preferably achieved using trapdoors, discharge flaps, separating diverters, blow-off nozzles, or combinations thereof. However, any separation device can be used. The separation of the identified LED components from the non-LEED components after shredding the LED lamps is preferably achieved using blow-off nozzles. However, any separation device can be used.

[0014] Preferably, the mechanical comminution in step e) is carried out by a shredder, a hammer mill, an impact mill, electrohydraulic comminution or combinations thereof.

[0015] A preferred radiation source is an LED lamp, an LED cluster, or a laser with a diffusing optic. Blue or white light sources can also be used in combination with a filter or filter combination transparent in the 400 nm to 500 nm range. In principle, any radiation source emitting light within a narrowly defined wavelength range between 400 nm and 500 nm can be used. Multiple radiation sources can be employed, and any combination of the aforementioned sources is possible. It is also preferred to use multiple radiation sources covering different wavelength ranges.

[0016] Preferably, photomultiplier tubes, photodiodes, CCD sensors, lux meters, or combinations thereof are used as detectors. If multiple detectors are used, it is also possible to arrange them at different positions in the irradiation chamber.

[0017] A preferred variant of the method involves separating the waste lamp mixture into small fractions using partitions for improved detection, with each fraction being transported individually through the measuring chamber. This allows for improved, i.e., more accurate, detection.

[0018] The irradiation chamber preferably has several radiation sources, in particular radiation sources on all sides of the irradiation chamber. Alternatively, it is preferred that the irradiation chamber has at least one reflective element for the homogeneous irradiation of the waste lamp mixture.

[0019] To avoid direct detection of the radiation emitted by the radiation source, the detector is preferably protected with an optical filter, in particular an edge filter.

[0020] According to the invention, a device for recycling LED components from a mixture of waste lamps is also provided, comprising an irradiation chamber with at least one radiation source emitting light in the wavelength range of 400 to 500 nm, at least one detector for measuring the illuminance of the light emitted by the radiation source, and at least one separation device.

[0021] The at least one radiation source is preferably selected from the group consisting of LED lamps, LED clusters, lasers with diffusing optics, blue or white light sources in combination with a filter or filter combination transparent in the 400 nm - 500 nm range, and combinations thereof. However, in principle, all radiation sources that emit light in a narrowly defined wavelength range between 400 nm and 500 nm can be used.

[0022] The irradiation chamber preferably has transparent walls, with both the radiation source and the detector located outside the chamber. Alternatively, the radiation source and detector may be located inside the chamber, but the detector must be protected from the excitation light by a filter. The irradiation chamber must be shielded from external radiation sources, for example, by enclosing the entire recycling apparatus or a section thereof.

[0023] The at least one separating device is preferably selected from the group consisting of a trapdoor, a discharge flap, a separating diverter, discharge nozzles, ejectors of other types or combinations thereof.

[0024] A preferred method for separating LEDs from other components after lamp shredding involves illuminating the components moving on a conveyor belt with blue light of a wavelength between 400 nm and 500 nm. The light emitted by the fluorescent phosphor layers of the LEDs is then spatially resolved (e.g., using a line scan camera). This signal is used as a trigger to activate a corresponding separation mechanism (e.g., blow-off nozzles).

[0025] The device according to the invention is used for identifying and separating light-emitting diodes and / or fluorescent lamps from a mixture of waste lamps or for separating light-emitting diodes from fluorescent lamps from a mixture of waste lamps.

[0026] The following figures and examples will be used to explain the method according to the invention in more detail, without limiting it to the specific embodiments shown here. Fig. Figure 1 shows different types of LED lamps and a CFL with YAG:Ce phosphor that were used in the examples. Fig. Figure 2a shows the fluorescence spectra of the in Fig. 1. High-intensity lamps shown (excited with blue light of wavelength 470 nm) Fig. Figure 2b shows the fluorescence spectra of the in Fig. 1. Low-intensity lamps shown (excited with blue light of wavelength 470 nm) Fig. Figure 3 shows, using a schematic representation, the measurement setup for determining the illuminance of the surface excited by blue light from an LED or a blue laser. Fig. Figure 4 shows in a diagram the illuminance (measured under excitation with a laser of the lamps under investigation) Fig. Figure 5 shows the illuminance in a diagram (measured under excitation with a blue LED with a wide beam angle). Fig. Figure 6 shows various types of LED lamps and CFLs used according to the invention. Fig. Figure 7 shows X-ray stimulated luminescence spectra of the LED lamps and CFLs from Fig. 6 Examples

[0027] In an experiment, the fluorescence of various LED lamps and one of the rare compact fluorescent lamps (CFLs) on the market was measured. This CFL contains a proportion of cerdoped yttrium aluminum garnet (YAG:Ce) to produce warm white light, which can also be excited with blue light. Excitation was achieved using blue light with a wavelength of 470 nm.

[0028] The lamps were positioned in the spectrometer in such a way that the phosphor layers were optimally illuminated by the excitation light, while simultaneously enabling the best possible detection of the excitation light. The lamps were left as they were when removed from the collection of old lamps. Therefore, the phosphor layers were partly visible and partly covered by diffusers, flat or round plastic or glass modules, and / or optical modules, thus making them more or less accessible to the excitation light. The LED lamps 200, 203, and the CFL (see...) Fig. 1 top right: Osram Dulux Superstar Micro Twist) show the typical YAG:Ce spectrum ( Fig. 2) All other LED lamps contain multiple phosphors or modified YAG:Ce phosphors, which can be seen in their different spectra.

[0029] Even though only a small number of CFLs with excitability in the blue spectral range are on the market, this fact necessitates a further distinction between LEDs and fluorescent lamps, as well as lamps that cannot glow when excited with blue light, such as incandescent and halogen lamps.

[0030] Since fluorescent lamps use more than 100 times the amount of phosphor, YAG:Ce fluorescent lamps stand out due to significantly higher emitted light intensities compared to LED lamps under the same excitation conditions. This is due to the spectrum in Fig. 2. The distinction can therefore be achieved by registering only lamps with a measured fluorescence intensity up to a threshold value dependent on the excitation intensity as LED lamps. Intensities above this threshold are to be classified as CFLs.

[0031] A simple experimental setup was used to test the differentiation between CFLs and LEDs based on the intensity differences of their fluorescence light. A closed box served as the sample chamber. The lamps placed inside were selectively illuminated with either a blue laser or a blue-emitting LED. The illuminance of the emitted light from the lamp was measured using a lux meter. To prevent the detection of the blue excitation light, the lux meter was covered with an edge filter. (see...) Fig. 3)

[0032] The laser measurements clearly show that all LED lamps can be excited with blue light and emit light in the process (see...). Fig. 4) This also applies to the two tested CFLs with a YAG:Ce component. Due to the targeted focusing on the phosphor of one of the LEDs in each lamp, the intensities of the emitted light are sometimes very high, while the intensity of the CFLs is rather medium to low. This is due to the even distribution of the phosphor in the CFLs on the inside of the glass tube. When the light is focused on the outside of the tube, only a small portion of the phosphor is excited.

[0033] Therefore, in a second experiment, a blue LED was used for wide-angle excitation, allowing for largely uniform excitation of the entire lamp. With this setup, the emitted luminous intensity of some LED lamps fell below the detection limit. This is due to the low intensity of the excitation lamp. However, it was clearly demonstrated that all LED lamps exhibited lower illuminance levels than the CFLs, which can be attributed to the significantly higher amounts of phosphor, its large-area distribution, and the uniform excitation across the entire lamp.

[0034] With optimal homogeneous light distribution throughout the entire sample chamber and significantly higher excitation intensities, the effect of different phosphor quantities on the different emitted light of CFLs and LEDs can be further enhanced. This is to be achieved through large-area primary illumination (e.g., by diode clusters) and full mirroring of the measurement chamber. This also makes the position of the lamp being measured irrelevant.

[0035] When implemented on a pilot plant or industrial scale, a series of individual chambers is used to achieve the required throughput.

[0036] Furthermore, it is possible to connect additional sensors. High-energy radiation, especially X-rays, also excites the phosphors contained in fluorescent and LED lamps, causing them to glow. Unlike blue light and UV radiation, X-rays penetrate glass and plastic and therefore always result in light emission. LED lamps emit light above 480 nm, while the phosphor mixtures in fluorescent lamps also generate blue light down to below 400 nm and a high proportion of red light above 600 nm. Emission upon X-ray excitation is possible for some lamps (see...). Fig. 6) in the spectra in Fig. Figure 7 shows that CFLs can be selected by selectively detecting the regions above 600 nm and below 470 nm during X-ray excitation. In summary, the sensor system works as follows:

[0037] In the first step, the fluorescence light is measured when excited with blue light between 400 nm and 500 nm. The measured intensity serves as an indicator to differentiate between CFL and LED lamps. The CFL either shows no light at all (if it does not contain YAG) or very high intensities compared to the LED lamps (if YAG is applied to the entire inside of the tube).

[0038] In an (optional) second step, the fluorescence light is measured when excited with X-rays. This can be performed as a safety measure after the first step, but is not necessary if the first step was properly calibrated. In this case, light below 470 nm and above 600 nm is detected. The measured intensities are significantly higher for CFLs than for LEDs, thus enabling differentiation.

[0039] Detecting LED chips from fractions of shredded lamps requires only distinguishing between luminescent and non-luminescent components. Excitation is achieved using light with a wavelength between 400 nm and 500 nm. LEDs with a phosphor coating are excited by this light and emit light with wavelengths above the excitation light. A detector and an edge filter placed between the sample and the detector, which absorbs light at the wavelength of the excitation light, identify the LED chips. These chips can then be separated from the other components using compressed air nozzles. The material mixture of the shredded lamps travels along a conveyor belt. At the end of the belt, the individual pieces fall in different directions, depending on whether or not they are struck by the air jet from the nozzles.

Claims

[1] Process for recycling LED components from a waste lamp mixture, in which a) a mixture of used lamps is fed into an irradiation chamber, b) the waste lamp mixture is irradiated with a radiation source emitting in the wavelength range of 400 to 500 nm, whereby the LED lamps excited to fluorescence by the irradiation emit fluorescent radiation, c) the emitted fluorescent radiation is detected with a detector and thus the LED lamps are identified, d) the identified LED lamps are separated from the remaining waste lamp mixture, e) the separated LED lamps are subjected to mechanical comminution, f) the crushed LED lamps consisting of LED components and non-LED components are irradiated with a radiation source emitting in the wavelength range of 400 to 500 nm, whereby the LED components excited to fluorescence by the irradiation emit fluorescent radiation, g) the emitted fluorescent radiation is detected with a detector and the LED components are thus identified and h) the identified LED components are separated from the non-LED components. [2] Method according to claim 1, characterized by that the separation in step d) is effected by trap doors or ejection flaps, separating gates, blow-out nozzles or combinations thereof and / or the separation in step h) is effected by blow-out nozzles. [3] Method according to one of the preceding claims, characterized by that the mechanical comminution in step e) is carried out by shredder, hammer mill, impact mill, electro-hydraulic comminution. [4] Method according to one of the preceding claims, characterized by that the radiation source is selected from the group consisting of LED lamps, LED clusters, lasers with scattering optics, blue or white light sources in combination with a filter transparent in the range 400 nm - 500 nm or filter combination and combinations thereof. [5] Method according to one of the preceding claims, characterized by that the detector is selected from the group consisting of photomultipliers, photodiodes, CCD sensors, lux meters or combinations thereof. [6] Method according to one of the preceding claims, characterized by that the waste lamp mixture is divided into small fractions via partition walls for improved detection and these fractions are each transported individually through the measuring chamber. [7] Method according to one of the preceding claims, characterized bythat the irradiation chamber has several radiation sources, in particular radiation sources on all sides of the irradiation chamber, and / or at least one reflective element for homogeneous irradiation of the waste lamp mixture. [8] Method according to one of the preceding claims, characterized by that in order to avoid direct detection of the radiation emitted by the radiation source, the detector is protected with an optical filter, in particular an edge filter. [9] Method according to one of the preceding claims, characterized by that the LED components are selected from the group consisting of LED chips, LED-equipped circuit boards, phosphor layers and mixtures thereof.

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