Sorting out waste glass cullet having a higher iron oxide content
Patent Information
- Application Number
- EP2023195961
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-09-07
- Publication Date
- 2025-03-12
Smart Images
Figure IMGAF001_ABST
Abstract
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a method for sorting out waste glass cullet with a higher iron oxide content from a single-layer material stream of waste glass cullet, wherein the material stream contains waste glass cullet with a higher and with a lower iron oxide content, as well as to a corresponding sorting system and a corresponding computer program product.
[0002] The waste glass cullet may include, in particular, shards of container glass, flat glass, window glass, bottles, facade glass and vehicle windows.
[0003] Single-layer means that the individual pieces of waste glass are not stacked on top of each other, but rather next to each other, meaning they do not overlap over a large area. Ideally, the individual pieces of waste glass should be spaced apart so that they can be easily identified as individual objects by optical devices.
[0004] The material stream may consist exclusively of waste glass shards, but it is also conceivable that the material stream contains other objects in addition to waste glass shards, such as objects made of plastic, ceramics, stones, etc. These could also be removed based on other criteria, such as very low transparency.
[0005] The present invention is primarily intended to detect waste glass cullet with a higher content of iron oxide in the form of Fe 2 O 3. STATE OF THE ART
[0006] Certain properties of waste glass cullet can be detected using visible light and optical sensors and used for sorting purposes. If waste glass cullet has a high Fe2O3 content, it appears greenish. Separating waste glass cullet with a high to medium iron oxide content from waste glass cullet with a low iron oxide content is desirable because waste glass cullet with a low iron oxide content can be processed into higher-quality glass in a processing plant. However, with a low iron oxide content, the iron oxide content is difficult to detect due to the faint color. PRESENTATION OF THE INVENTION
[0007] It is therefore an object of the present invention to provide a method and a corresponding sorting system where waste glass cullet in a single-layer material stream can be classified according to its iron oxide content with as little effort as possible and can be separated at least into a fraction with a higher and a fraction with a lower iron oxide content.
[0008] This object is achieved by a method according to claim 1 in such a way that that the material flow is irradiated with visible light and the visible transmission light passing through the waste glass cullet is detected, that the material flow is irradiated with infrared light in a frequency range of at least 1100-1200 nm and the infrared transmission light passing through the waste glass cullet is detected, that a waste glass cullet is classified as having a higher iron oxide content if the ratio of the intensity of the infrared transmission light to the intensity of the visible transmission light exceeds or falls below a predetermined threshold, and that waste glass cullet classified in this way is separated from other waste glass cullet.
[0009] Investigations by the inventors have surprisingly shown that waste glass cullet exhibits a spectral attenuation in the near infrared range from 1100 to 1200 nm, depending on its iron oxide content. The attenuation is greater the higher the iron oxide content. However, the attenuation is also measurable in waste glass cullet with a low iron oxide content. Different wall thicknesses and possible and unavoidable contamination of the waste glass cullet do impair the transmission measurement in the infrared range, but this impairment can be compensated for by additional transmission measurement in the visible range, preferably in the range from 400 to 650 nm. A complex determination of the wall thicknesses of the waste glass cullet, e.g.According to the inventors' research, laser measurement can be avoided if the intensities of the two spectral ranges, visible and infrared, are compared. This ratio can be used as a measure of transparency with respect to eixene oxide.
[0010] The visible transmitted light passing through the waste glass cullet is also used to determine the shape and spatial position of the waste glass cullet so that it can then be separated from other waste glass cullet according to its iron oxide content by deflection units of a sorting device.
[0011] One embodiment of the invention provides that when detecting the visible transmission light passing through the waste glass shards, an intensity of a red, a green and a blue spectral range is determined, and either the highest value or the mean value of the three intensities is used as the intensity of the visible transmission light.
[0012] This allows a conventional color camera to be used to detect visible light, eliminating the need for special cameras. Additionally, the intensity of the red, green, and blue channels of the color camera can be easily read, with the highest of the three values or the average of the three values then being used as the intensity of the visible transmitted light to calculate the ratio of the intensity of the infrared transmitted light to the intensity of the visible transmitted light.
[0013] To use the simplest possible visible light sources, the visible light used to illuminate the material flow can be white light, and the visible transmitted light passing through the waste glass shards can be detected by a color camera. Thus, in this design variant, white light light sources are used, but a color camera is required to detect the visible transmitted light.
[0014] To use a monochrome camera for visible light, the visible light irradiating the material flow can be alternately red, green, and blue, and the visible transmitted light passing through the waste glass shards can be detected in a monochrome camera, preferably in the same monochrome camera. This requires one or more light sources that cyclically emit red, green, and blue light, so that an image of the same area of the material flow can be captured in the red, green, and blue frequency ranges, as quickly as possible.From these images taken with the help of the monochrome camera, the intensity of the transmitted light in the red, green and blue frequency range can then be determined for the individual pieces of waste glass, so that the highest or the average value of the three intensities in the ratio of the intensity of the infrared transmitted light to the intensity of the visible transmitted light is used as the intensity of the visible transmitted light.
[0015] For example, the red spectral range can encompass wavelengths from 570 to 650 nm. The intensity maximum for the red spectral range is typically in the range of 600 to 630 nm.
[0016] The green spectral range, for example, can encompass wavelengths from 470 to 570 nm. The intensity maximum for the green spectral range is typically in the range of 525 to 530 nm.
[0017] For example, the blue spectral range can encompass wavelengths from 400 to 470 nm. The intensity maximum for the blue spectral range is typically in the range of 430 to 450 nm.
[0018] One embodiment of the invention provides that the intensity of the infrared transmission light is determined as the mean value of the intensity in the frequency range of 1100-1200 nm.
[0019] In this case, the intensities are simply averaged over the entire meaningful frequency range of the infrared light and this average value is used as the intensity of the infrared transmission light in the ratio of the intensity of the infrared transmission light to the intensity of the visible transmission light.
[0020] The use of intensity in the entire frequency range of 1100-1200 nm is preferred.
[0021] An alternative embodiment of the invention provides that the intensity of the infrared transmitted light is the intensity in a sub-range of the frequency range of 1100-1200 nm. The sub-range can have a bandwidth of 10-20 nm, 20-30 nm, 30-40 nm, 40-50 nm, 50-60 nm, 60-70 nm, 70-80 nm, 80-90 nm, or 90 to less than 100 nm. The sub-range can be located at the lower end of the frequency range of 1100-1200 nm, at the upper end of the frequency range of 1100-1200 nm, or in between.
[0022] Here, only the mean intensity of a narrower frequency range within the relevant frequency range of infrared light is used, and this mean is used as the intensity of the infrared transmitted light in the ratio of the intensity of the infrared transmitted light to the intensity of the visible transmitted light. This has the advantage that higher sampling rates (clock rates) can be achieved with spectrally resolving infrared cameras.
[0023] As an alternative to infrared cameras with spectral resolution technology, infrared cameras with NIR-sensitive sensors can also be used. Filters can be used to limit the spectral range.
[0024] In order to be able to simultaneously sort out several classes of waste glass cullet containing different amounts of iron oxide, it may be provided that a further subdivision of waste glass cullet classified as having a higher iron oxide content is carried out based on the ratio of the intensity of the infrared transmission light to the intensity of the visible transmission light.
[0025] In particular, for this purpose, it can be provided that at least one further threshold value is specified for the further subdivision, which the ratio of the intensity of the infrared transmission light to the intensity of the visible transmission light exceeds or falls below.
[0026] Of course, in an analogous manner, even in the case of waste glass cullet that is generally classified as having a low iron oxide content, a further subdivision according to the iron oxide content can be made, for example by specifying a threshold value that determines the separation of waste glass cullet with a low and waste glass cullet with a very low iron oxide content.
[0027] In order to achieve a high throughput during sorting, it can be provided that the visible transmission light passing through the waste glass cullet and / or the infrared transmission light passing through the waste glass cullet is detected in the form of an image of several waste glass cullet.
[0028] In this way, multiple pieces of waste glass can be detected simultaneously in a single-layer material stream of waste glass cullet. Typically, the material stream has a defined width, and one image covers this width. Thus, multiple pieces of waste glass are usually captured simultaneously by one image.
[0029] In this embodiment of the invention, at least one image in the visible range and one image in the infrared range are created for the same pieces of waste glass (i.e., from the same region of the single-layer material stream). The at least one image in the visible range also defines the individual pieces of waste glass and their position.
[0030] Typically, the visible and infrared images are captured simultaneously, allowing for direct comparison. However, a slight delay between the first and second images is also possible and could be accounted for or compensated for during image processing.
[0031] The image in the visible range and the image in the infrared range are linked together - usually with image processing software - since they were created by different detectors, and processed, the waste glass shards are classified and sorted out at the correct time and place according to the sorting criteria.
[0032] In the method according to the invention, in one of several possible embodiments, it can be provided that the predetermined threshold value for the ratio of the intensity of the infrared transmission light, normalized to 1, to the intensity of the visible transmission light, normalized to 1, which threshold value determines the classification for a higher or lower iron oxide content, is greater than or equal to 0.9, preferably greater than or equal to 0.92, and a piece of waste glass is classified as having a higher iron oxide content if the ratio of the intensity of the infrared transmission light, normalized to 1, to the intensity of the visible transmission light, normalized to 1, is below the predetermined threshold value. The measured intensities of the transmission light are normalized to the value 1, i.e., they lie in the range from zero to 1.Since the measured intensities of the infrared transmitted light are usually smaller than the measured intensities of the visible transmitted light, the ratio of the intensity of the infrared transmitted light normalized to 1 to the intensity of the visible transmitted light normalized to 1 will usually be less than 1.
[0033] It is of course also conceivable that the threshold is less than 0.9.
[0034] A further subdivision of the waste glass cullet with a higher iron oxide content would be possible in the specific embodiment mentioned, for example, if a further threshold value was set below the specified threshold value of 0.9 and greater, preferably below 0.92 and greater, e.g., in the range from 0.7 to 0.8. Waste glass cullet with a ratio of the intensity of the infrared transmission light normalized to 1 to the intensity of the visible transmission light normalized to 1 of more than 0.9 and greater, preferably more than 0.92 and greater, is classified in this example as having a low iron oxide content.Glass cullet with a ratio of the infrared transmitted light intensity normalized to 1 to the visible transmitted light intensity normalized to 1 of 0.9 or less and greater, preferably 0.92 or less and greater (i.e., equal to or less than the specified threshold), but equal to or greater than 0.7 to 0.8 (i.e., equal to or greater than the further threshold) is classified as having a high iron oxide content. Glass cullet with a ratio of the infrared transmitted light intensity normalized to 1 to the visible transmitted light intensity normalized to 1 of less than 0.7 to 0.8 (i.e., less than the further threshold) is classified as having a very high iron oxide content.
[0035] Whether the waste glass cullet with a higher iron oxide content is separated from the waste glass cullet with a lower iron oxide content, or vice versa, is irrelevant during separation. The separation of one or more fractions can be achieved, for example, using compressed air through blow-out nozzles.
[0036] The sorting system for carrying out the method according to the invention is characterized in that it comprises at least: a first light source for visible light, with which a single-layer material stream of waste glass cullet can be illuminated, a first detector for visible light, with which the visible transmission light passing through the waste glass cullet, in particular in the form of an image of several pieces of waste glass cullet, can be detected, a second light source that can emit infrared light in a frequency range of at least 1100-1200 nm, a second detector for infrared light, with which the infrared transmission light passing through the waste glass cullet, in particular in the form of an image of several pieces of waste glass cullet, can be detected, a device for producing a single-layer material stream from waste glass cullet, with which the material stream can be guided past the two light sources, and a device for sorting,which then classifies a piece of waste glass as having a higher iron oxide content and separates it from other pieces of waste glass in the material stream if the ratio of the intensity of the infrared transmitted light to the intensity of the visible transmitted light exceeds or falls below a predetermined threshold.
[0037] The first and / or second light sources can each be composed of several individual light sources, in particular in order to be able to cover the entire width of the material flow of waste glass cullet. Likewise, the first and / or second detectors can each be composed of several individual detectors, in particular in order to be able to cover the entire width of the material flow of waste glass cullet.
[0038] The device for producing a single-layer material flow can, for example, comprise a conveyor belt or a conveyor trough which ends before the detection area and from which the waste glass shards either fall freely through the detection area or reach a translucent plate, e.g. a glass pane, which is inclined when the sorting system is in operation and on which they slide through the detection area.
[0039] The sorting system comprises an evaluation and control unit and one or more units for deflecting waste glass cullet, e.g., blow-out nozzles. The evaluation and control unit determines the shape and spatial position of the individual pieces of waste glass cullet and, based on the detector data, classifies them as those with a higher or lower iron oxide content. Based on the evaluation, the evaluation and control unit controls the unit(s) for deflecting waste glass cullet in such a way that at least one fraction of waste glass cullet with a higher and one fraction with a lower iron oxide content is created.
[0040] In one embodiment of the sorting system, the first light source for visible light is configured to emit visible white light, and the first detector is a color camera. The first light source is thus very simply designed. This embodiment of the sorting system allows the process variant to be implemented in which the visible light used to illuminate the material flow is white light, and the visible transmitted light passing through the waste glass cullet is detected by a color camera.
[0041] In an alternative embodiment of the sorting system, the first visible light source is configured to alternately emit red, green, and blue light, and the first detector is a monochrome camera. In this case, the first light source is more complex, but the camera is simpler. This embodiment of the sorting system allows the process variant to be implemented, according to which the visible light used to illuminate the material flow is alternately red, green, and blue light, and the visible transmitted light passing through the waste glass shards is detected in a monochrome camera, preferably in the same monochrome camera.
[0042] In both cases, the sorting device can be designed such that, when detecting the visible transmitted light passing through the waste glass cullet, an intensity of a red, a green and a blue spectral range is determined, and the highest or the average value of the three intensities is used as the intensity of the visible transmitted light.
[0043] The sorting device can be designed such that the intensity of the infrared transmitted light is determined as the mean value of the intensity in the frequency range of 1100-1200 nm or such that the intensity of the infrared transmitted light is the intensity in a sub-range of the frequency range of 1100-1200 nm.
[0044] The sorting device can further be configured such that, based on the ratio of the intensity of the infrared transmitted light to the intensity of the visible transmitted light, a further subdivision of waste glass cullet classified as having a higher iron oxide content is carried out. In particular, the sorting device can be configured such that at least one further threshold value is specified for the further subdivision, which the ratio of the intensity of the infrared transmitted light to the intensity of the visible transmitted light exceeds or falls below.
[0045] The sorting device can further be designed so that the visible transmitted light and / or the infrared transmitted light passing through the waste glass shards is detected in the form of an image of several pieces of waste glass shards. These two-dimensional images of waste glass shards are generated by the evaluation and control unit, for example, from image lines that run perpendicular to the direction of movement of the waste glass shards. Each of the two detectors, the first detector for visible light and the second detector for infrared light, captures image lines that run perpendicular to the direction of movement of the waste glass shards. These image lines are recorded at a high clock rate, usually between 0.3 and 20 kHz, and combined by image processing software in the evaluation and control unit into a two-dimensional image, in the form of a single image or a continuous film, of the material flow.Synchronization of the image lines of the two detectors is, of course, advisable in order to be able to combine and process the image data with the correct location and time. The movement speed of the waste glass cullet is typically between 1 and 3 m / s. Image lines are continuously recorded by the detectors at a clock rate between 0.3 and 20 kHz and blocked or saved as an image section. The evaluation and control unit combines the image lines from the detectors into images and performs the inventive evaluation, i.e., the classification of waste glass cullet into those with higher and lower iron oxide contents.
[0046] Since the method according to the invention is carried out on an industrial scale, e.g. with computer support, in particular using image processing programs to define the location, shape and position of the individual pieces of waste glass, the present invention also comprises a computer program product which comprises a program and can be loaded directly into a memory of a central processing unit of a sorting plant, which sorting plant at least a first light source for visible light, with which a single-layer material stream of waste glass cullet can be illuminated, a first detector for visible light, with which the visible transmission light passing through the waste glass cullet, in particular in the form of an image of several pieces of waste glass cullet, can be detected, a second light source that can emit infrared light in a frequency range of at least 1100-1200 nm, a second detector for infrared light, with which the infrared transmission light passing through the waste glass cullet, in particular in the form of an image of several pieces of waste glass cullet, can be detected, a device for producing a single-layer material stream from waste glass cullet, with which the material stream can be guided past the two light sources, and a device for sorting,which then classifies a piece of waste glass as having a higher iron oxide content and separates it from other pieces of waste glass in the material flow if the ratio of the intensity of the infrared transmitted light to the intensity of the visible transmitted light exceeds or falls below a predetermined threshold, includes, with program means to carry out all steps of the method according to the invention when the program is executed by the central processing unit.
[0047] The program may, for example, be stored on a data carrier, on a storage medium or on another computer-readable medium or be made available as a signal via a data connection.
[0048] In particular, the program will that the material flow is irradiated with visible light (whereby the irradiation can also be continuous and / or not controlled by the program) and the visible transmitted light passing through the waste glass cullet is detected, that the material flow is irradiated with infrared light in a frequency range of at least 1100-1200 nm (whereby the irradiation can also be continuous and / or not controlled by the program) and the infrared transmitted light passing through the waste glass cullet is detected, that a waste glass cullet is classified as having a higher iron oxide content if the ratio of the intensity of the infrared transmitted light to the intensity of the visible transmitted light exceeds or falls below a predetermined threshold, and that waste glass cullet classified in this way is separated from other waste glass cullet.
[0049] Furthermore, the program could also carry out the method steps of claims 2-10. SHORT DESCRIPTION OF THE CHARACTERS
[0050] The invention will now be explained in more detail with reference to schematic figures illustrating exemplary embodiments of a sorting system according to the invention. The backlight method is used for visible light and infrared light, respectively, meaning that the light source and detector are arranged on opposite sides of the material flow. Fig. 1 shows a sorting system according to the invention, Fig. 2 shows spectra of the transmitted light of different waste glass shards with different iron oxide contents, Fig. 3 shows a diagram of the ratio of the intensity of infrared transmission light to the intensity of visible transmission light according to the spectra of the waste glass cullet from Fig. 2 . WAYS OF IMPLEMENTING THE INVENTION
[0051] In Fig. 1A first light source 1 for visible light and a second light source 2, which can emit infrared light in a frequency range of at least 1100-1200 nm, are arranged such that they can irradiate waste glass cullet 3 through an obliquely arranged glass pane 7. The visible transmission light of the first light source 1 that has passed through the waste glass cullet 3 is detected in a first detector 4 for visible light. The infrared transmission light of the second light source 2 that has passed through the waste glass cullet 3 is detected in a second detector 5 for infrared light. The waste glass cullet 3 is placed on a conveyor belt or conveyor trough 6 and conveyed by this onto the obliquely arranged glass pane 7, where it slides downwards under the force of gravity.After the lower end of the glass pane 7, at least one blow-out nozzle 9 is arranged, which blows off the waste glass cullet 3 falling from the glass pane 7 on the basis of the control signals (see arrows) of the evaluation and control unit 8, so that it falls to the left of a partition 10 downwards into a first container 11 for the first fraction, e.g. for waste glass cullet 3 with a higher iron oxide content, or which does not blow off the waste glass cullet 3 falling from the glass pane 7 on the basis of the control signals (see arrows) of the evaluation and control unit 8, so that it falls undisturbed to the right of a partition 10 downwards into a second container 12 for the second fraction, e.g. for waste glass cullet 3 with a lower iron oxide content.
[0052] Of course, it would also be possible for the blow-out nozzles 9 to be arranged (exclusively or also) on the opposite side of the material flow and, if necessary, to blow on waste glass cullet 3 so that it falls downwards to the right of the partition wall 10 into the second container 12, while other waste glass cullet 3 is not blown on and falls into the first container 11.
[0053] The manner in which the waste glass cullet 3 with different iron oxide contents is mechanically separated from one another is not essential to the invention.
[0054] The first light source 1 emits white light in the range of at least 400 to 650 nm. The first light source 1 can be formed by one or—in particular, to cover the entire width of the material flow of waste glass cullet 3—several LED lights.
[0055] The second light source 2 emits light in the infrared range, covering at least the wavelength range from 1100 to 1200 nm. Light sources that cover a broad infrared spectrum, e.g., the range from 600 to 1300 nm, can be used, for example, using one or more infrared halogen lamps—particularly to cover the entire width of the material flow of waste glass cullet 3. However, light sources tailored to the required range, e.g., covering the range from 1100 to 1300 nm, can also be used, for example, using infrared LED lamps.
[0056] The glass pane 7 serves as a chute for the waste glass cullet 3 to be examined. When the sorting system according to the invention is assembled, it has an inclination of approximately 60°. The waste glass cullet 3 slides downwards on it and is illuminated by the two light sources 1, 2. It is essential that the material for the glass pane 7 serving as the chute is transparent to light at least in the range of 400-1200 nm.
[0057] The spatial distance between the visible transmission light to be detected and the infrared transmission light to be detected should be as small as possible so that both detectors 4, 5, the one for visible light and the one for infrared light, can produce the most consistent image possible of the waste glass cullet 3.
[0058] The first detector 4, for detecting visible transmitted light, is sensitive in a wavelength range of 400–650 nm; if necessary, the sensitivity can be narrowed to this wavelength range using filters. The first detector 4 is typically designed as a color camera. It can, for example, be configured as an RGB camera. The measurement results from the color camera can be divided into the red, green, and blue color ranges by internal filtering. Thus, the colors red, green, and blue are each transmitted or stored in a separate channel.
[0059] To detect the position and shape of the individual pieces of waste glass 3, the first detector 4 must be able to provide at least data for an image of the pieces of waste glass 3 in shades of gray. From this, the position and shape of the individual pieces of waste glass 3 can then be determined, which are necessary to remove them from the material stream using downstream units for deflecting the pieces of waste glass, in this case, blow-out nozzles 9.
[0060] The first detector 4 could also be designed as a monochrome camera if the first light source 1 emits alternating red, green, and blue light instead of white light. The intensity of the transmitted light in the red, green, and blue frequency ranges can then be determined successively, each time by taking a monochrome image.
[0061] The second detector 5 is usually an infrared camera and is sensitive at least in the range of 1100-1200 nm.
[0062] The data detected by the two detectors 4, 5 are fed to the evaluation and control unit 8, which evaluates the two images and assigns the individual pieces of waste glass 3 to the different fractions and controls the blow-out nozzles 9, which transport the pieces of waste glass 3 into the corresponding containers 11, 12.
[0063] The exposure time for both the first detector 4 for visible light and the second detector 5 for infrared light is, for example, in the range of 2 microseconds to 10,000 microseconds. This allows for a high frame rate and high-resolution imaging.
[0064] The obliquely aligned glass pane 7 could also be shortened. In this case, the area where the light from the two light sources 1, 2 hits the waste glass shards 3 could be aligned in the direction of movement of the waste glass shards 3 (from top to bottom in Fig. 1) after the glass pane 7, i.e., below the lower edge of the glass pane 7. This would have the advantage that no translucent material would be required for the chute, and that contamination of the chute would not affect the measurement result. The disadvantage of the shortened chute is that the waste glass cullet 3 is guided for a shorter distance, which can have a negative impact on the discharge efficiency, especially with small waste glass cullet 3.
[0065] In Fig. 1 The connection of the detectors 4, 5 to the evaluation and control unit 8 is shown, usually a processing unit (e.g., a computer), which can, for example, form the central processing unit of a sorting system and which executes the program according to the invention. This evaluation and control unit 8 combines the image lines of the detectors 4, 5 into images and performs the evaluation according to the invention.
[0066] Depending on this evaluation, the deflection units are controlled, such as in this case one or more blow-out nozzles 9. These are arranged below the glass pane 7 (or below a chute made of non-transparent material) and below the area where the waste glass cullet 3 is irradiated.
[0067] It would also be conceivable to separate the waste glass cullet 3 into three fractions, whereby the waste glass cullet 3 with a higher iron oxide content would be further subdivided, e.g. into a fraction with a medium iron oxide content and a fraction with a high iron oxide content.
[0068] In Fig. 2The intensity of the transmitted light is shown for various types of waste glass cullet 3, normalized in the wavelength range of approximately 380–1680 nm, here in the range of 0–100%. The intensities were determined in experimental measurements. Thirteen different types of waste glass with a low iron oxide content were measured (see dashed spectra LI-101 to LI-113), thirteen different types of waste glass with a medium iron oxide content (see solid spectra MI-201 to MI-213), and one type of waste glass with a high iron oxide content (see dotted spectrum HI-301).
[0069] It can be seen that for most cullet 3 of the waste glass types with a low iron oxide content, the intensity in the visible wavelength range is generally somewhat higher than in the infrared range around 1100-1200 nm. However, the difference is not very significant, only a few percentage points. For cullet 3 of the waste glass types with a medium iron oxide content, the difference between the intensity in the visible wavelength range and in the infrared range around 1100-1200 nm is already larger. However, the difference between the intensity in the visible wavelength range and in the infrared range around 1100-1200 nm is greatest for the waste glass type with a high iron oxide content. Here, the maximum intensity in the green spectral range around 530 nm is approximately 88% (or 0.88 when normalized to 1), while in the infrared range around 1100-1200 nm it is approximately 67% (or 0.67 when normalized to 1).
[0070] In Fig. 3is for the individual spectra from Fig. 2 The ratio of the intensity of infrared transmitted light in the range around 1100-1200 nm to the maximum intensity occurring in either the red, green, or blue spectral range is expressed as a percentage. This ratio serves as a measure of transparency based on the iron oxide content and is used as a characteristic for classifying the iron oxide content.
[0071] On the left, the ratios for the waste glass types with low iron oxide content are plotted, in the middle the ratios for the waste glass types with medium iron oxide content are plotted, and on the far right the ratio for the waste glass type with high iron oxide content is plotted. The iron oxide content increases from left to right in groups (LI, MI, HI). The individual ratios are connected by the solid line and tend to decrease from left to right. If one now sets a threshold value of, for example, 93% (or 0.93 when normalized to 1), see dashed horizontal line, knowing the iron oxide content and the intensities measured in the test measurements, the ratios on the left side of the Fig. 3 largely above this threshold, while the conditions on the right side of the Fig. 3 largely lie below this threshold.
[0072] According to this example, in the industrial application of the method according to the invention to any waste glass cullet, those waste glass cullet where the ratio is above 93% (or above 0.93 when normalized to 1) are classified as waste glass cullet with a lower iron oxide content and those waste glass cullet where the ratio is below 93% (or below 0.93 when normalized to 1) are classified as waste glass cullet with a higher iron oxide content.
[0073] Since the iron oxide content and the corresponding intensities were determined during the experimental measurements, a further threshold could also be defined for industrial applications, e.g., at 80% (or 0.8 when normalized to 1). Glass cullet with a ratio of the infrared transmitted light intensity to the visible transmitted light intensity of more than 93% (or 0.93) is classified in this example as having a low iron oxide content. Glass cullet with a ratio of the infrared transmitted light intensity to the visible transmitted light intensity of less than 93% (or 0.93) but more than 80% (or 0.8) is classified as having a medium iron oxide content. Glass cullet with a ratio of infrared transmission light intensity to visible transmission light intensity of less than 80% (or less than 0.8) is classified as having a high iron oxide content. List of reference symbols:
[0074] 1First light source for visible light 2Second light source (for infrared light) 3Waste glass shard 4First detector for visible light 5Second detector for infrared light 6Conveyor trough 7Glass pane (chute) 8Evaluation and control unit (sorting device) 9Blow-out nozzle (sorting device) 10Partition wall (sorting device) 11First container for the first fraction (sorting device) 12Second container for the second fraction (sorting device)
Claims
1. A method for sorting out waste glass cullet with a higher iron oxide content from a single-layer material stream of waste glass cullet (3), wherein the material stream contains waste glass cullet with a higher and a lower iron oxide content, characterized by - that the material flow is irradiated with visible light and the visible transmission light passing through the waste glass shards (3) is detected, - that the material flow is irradiated with infrared light in a frequency range of at least 1100-1200 nm and the infrared transmission light passing through the waste glass shards (3) is detected, - that a waste glass cullet (3) is classified as having a higher iron oxide content if the ratio of the intensity of the infrared transmitted light to the intensity of the visible transmitted light exceeds or falls below a predetermined threshold, and - thatbroken glass classified in this way must be separated from other broken glass.
2. Method according to claim 1, characterized in that when detecting the visible transmission light passing through the waste glass cullet (3), an intensity of a red, a green and a blue spectral range is determined, and either the highest value or the mean value of the three intensities is used as the intensity of the visible transmission light.
3. Method according to one of claims 1 to 2, characterized in that the intensity of the infrared transmitted light is determined as the average value of the intensity in the frequency range of 1100-1200 nm.
4. Method according to one of claims 1 to 2, characterized in that the intensity of the infrared transmitted light is the intensity in a sub-range of the frequency range of 1100-1200 nm.
5. Method according to one of claims 1 to 4, characterized in thatbased on the ratio of the intensity of the infrared transmitted light to the intensity of the visible transmitted light, a further subdivision of waste glass cullet classified as having a higher iron oxide content is carried out.
6. Method according to claim 5, characterized in that for the further subdivision, at least one further threshold value is specified, which the ratio of the intensity of the infrared transmission light to the intensity of the visible transmission light exceeds or falls below.
7. Method according to one of claims 1 to 6, characterized in that the visible light for irradiating the material flow is white light and the visible transmission light passing through the waste glass shards (3) is detected in a color camera.
8. Method according to one of claims 1 to 6, characterized in thatthe visible light for irradiating the material flow is alternately red, green and blue light and the visible transmission light passing through the waste glass shards (3) is detected in a monochrome camera, preferably in the same monochrome camera.
9. Method according to one of claims 1 to 8, characterized in that the visible transmission light passing through the waste glass shards (3) and / or the infrared transmission light passing through the waste glass shards (3) is detected in the form of an image of several waste glass shards (3).
10. Method according to one of claims 1 to 9, characterized in thatthe predetermined threshold value for the ratio of the intensity of the infrared transmission light normalized to 1 to the intensity of the visible transmission light normalized to 1 is greater than or equal to 0.9, preferably greater than or equal to 0.92, and a waste glass cullet (3) is classified as having a higher iron oxide content if the ratio of the intensity of the infrared transmission light normalized to 1 to the intensity of the visible transmission light normalized to 1 is below the predetermined threshold value.
11. Sorting system for carrying out a method according to one of claims 1 to 10, characterized in thatThis comprises at least: - a first light source (1) for visible light, with which a single-layer material stream of waste glass cullet (3) can be illuminated, - a first detector (4) for visible light, with which the visible transmission light passing through the waste glass cullet (3), in particular in the form of an image of several waste glass cullet (3), can be detected, - a second light source (2) that can emit infrared light in a frequency range of at least 1100-1200 nm, - a second detector (5) for infrared light, with which the infrared transmission light passing through the waste glass cullet (3), in particular in the form of an image of several waste glass cullet (3), can be detected, - a device (6, 7) for producing a single-layer material stream from waste glass cullet (3), with which the material stream can be guided past the two light sources (1, 2), and - a device (8-12) for sorting,which then classifies a waste glass cullet (3) as having a higher iron oxide content and separates it from other waste glass cullet in the material stream if the ratio of the intensity of the infrared transmission light to the intensity of the visible transmission light exceeds or falls below a predetermined threshold value.
12. Sorting system according to claim 11, characterized in that the first light source (3) for visible light is designed to emit white light and the first detector (4) is a color camera.
13. Sorting system according to claim 11, characterized in that the first light source (1) for visible light is designed to alternately emit red, green and blue light and the first detector (4) is a monochrome camera.
14. A computer program product comprising a program and being directly loadable into a memory of a central processing unit of a sorting system, said sorting system comprising at least - a first light source (1) for visible light, with which a single-layer material stream of waste glass cullet (3) can be illuminated, - a first detector (4) for visible light, with which the visible transmission light passing through the waste glass cullet (3), in particular in the form of an image of several waste glass cullet (3), can be detected, - a second light source (2) that can emit infrared light in a frequency range of at least 1100-1200 nm, - a second detector (5) for infrared light, with which the infrared transmission light passing through the waste glass cullet (3), in particular in the form of an image of several waste glass cullet (3), can be detected, - a device (6, 7) for producing a single-layer material stream from waste glass cullet (3),with which the material flow can be guided past the two light sources (1, 2), and - a device (8-12) for sorting, which then classifies a piece of waste glass (3) as having a higher iron oxide content and separates it from other pieces of waste glass in the material flow if the ratio of the intensity of the infrared transmission light to the intensity of the visible transmission light exceeds or falls below a predetermined threshold value, with program means for carrying out all steps of the method according to one of claims 1 to 10 when the program is executed by the central processing unit.
Citation Information
Patent Citations
Method and device for sorting
EP0426893A1