System for analyzing and sorting pieces of material

Abstract

The present invention relates to a system for analyzing and sorting scrap pieces of material, in particular aluminum scrap pieces, comprising: a feeding means (110) for conveying the material pieces (120); a sorting unit (160) designed to feed the material pieces (120) into one of two fractions (F1, F2); a laser device (140) designed to generate a plasma (3) on a surface (7A) of the material pieces (120) by means of a laser beam (5) propagating along a beam axis (5A); a spectrometer system (1) designed to perform a spectral analysis of the plasma light (3A) emitted from the laser-induced plasma (3) and to generate an output signal according to the result of the performed spectral analysis; and a control device (150) designed to receive the output signal and operate the sorting unit (160) on the basis of the output signal and sorting criteria, the spectrometer system (1) comprising a spectrometer (13) and a sorting unit (160) designed to generate a plasma (3) on a surface (7A) of the material pieces (120) by means of a laser beam (5) propagating along a beam axis (5A). and a detection unit (21) optically connected to the laser beam (5), the detection unit (21) having lenses (25A, 25B, 25C, 25D), each of which is assigned a detection cone (35), the detection cone (35) forming a plasma detection region (39) in an overlap region (37) with the laser beam (5), and the supply means (110) being arranged successively in front and behind the material piece (120) in the conveying direction (207). The feed assembly (201, 202, 203) has three individual feed assemblies (201, 202, 203) arranged in a vertical direction, each feed assembly (201, 202, 203) designed to convey the material pieces (120) along a feed surface (204, 205, 206) provided by the respective feed assembly (201, 202, 203), the feed surfaces (204, 205, 206) each being inclined relative to the horizontal to form a respective inclination angle (α1, α2, α3), the inclination angles (α1, α2, α3) being inclined relative to the horizontal to form a respective inclination angle (α1, α2, α3)The inclination angle (α1) of the supply surface (204) of the first supply assembly (201) in the conveying direction (207) is smaller than the inclination angle (α2) of the supply surface (205) of the second supply assembly (202) in the conveying direction (207), and the inclination angle (α2) of the supply surface (205) of the second supply assembly (202) in the conveying direction (207) is smaller than the inclination angle (α3) of the supply surface (206) of the third supply assembly (203) in the conveying direction (207).

Description

[Technical Field]

[0001] The present invention relates to a system for analyzing and sorting material pieces, in particular aluminum scrap pieces, comprising: a feeding means for conveying the material pieces; a sorting unit designed to feed the material pieces into one of two fractions; a laser device designed to generate a plasma on the surface of the material pieces by means of a laser beam propagating along a beam axis; a spectrometer system designed to perform a spectral analysis of the plasma light emitted by the laser-induced plasma and to generate an output signal according to the results of the performed spectral analysis; and a spectrometer system designed to receive the output signal and operate the sorting unit based on the output signal and on sorting criteria. , and a control device, wherein the spectrometer system comprises an optical spectrometer and a detection unit optically connected to the optical spectrometer, the detection unit having an objective lens, the objective lens having a detection cone assigned to it, the detection cone forming a plasma detection area in an overlapping region with the laser beam, and the supply means comprises three individual supply units arranged one behind the other in a conveying direction of the material pieces, each supply unit being configured to convey the material pieces along a supply surface provided by the respective supply unit, the supply surfaces being inclined at respective inclination angles with respect to the horizontal, the inclination angles being different. [Background technology]

[0002] A system for analyzing and sorting material pieces is known from US Pat. No. 5,699,499. The previously known system is based on laser-induced plasma spectroscopy, also known as LIBS (Laser-Induced Breakdown Spectroscopy), and allows sorting of material pieces, in particular aluminum scrap pieces. In this process, laser-induced plasma spectroscopy is used to determine the element-specific composition of a material piece (i.e., a sample) using a plasma. The plasma is generated by high-intensity focused laser radiation on the surface of the material piece. The light emitted by the plasma is detected and spectrally analyzed to deduce the elemental composition of the material piece.

[0003] Furthermore, a device for sorting waste, in particular waste glass, according to its color is known from US Pat. No. 5,629,999, using a vibrating bar screen, a separating device and an optoelectronic measuring and sorting device.

[0004] A method and an apparatus for sorting waste into different types of waste are known from reference 3. The apparatus comprises a first conveyor, a second conveyor, a third conveyor, unloading means, identification means, recording and control means and means for separating the waste.

[0005] According to a system known from Patent Document 4, an apparatus for sorting bulk materials, particularly pellets, includes a vibrating conveyor system, a feeding means for feeding the bulk material to the vibrating conveyor system, a first outlet and a second outlet, a detector, and a sorting device for influencing the trajectory of the bulk material so that bulk material identified as defective falls into the second outlet. Rotationally driven rollers are adjacent to the ends of the vibrating conveyor system, and bulk material conveyed beyond the ends of the vibrating conveyor system reaches the rollers, which convey the bulk material in a trajectory predetermined by the rotation of the rollers toward the first outlet. It is suggested that one or more vibrating conveyor systems can include multiple vibrating conveyors arranged one behind the other in the bulk material conveying direction. Two or more of the multiple vibrating conveyors can be arranged at different angles relative to the horizontal.

[0006] According to the system known from D1, the material pieces to be sorted are fed to a feeding means, which may for example be a vibrating plate providing a feeding surface along which the material pieces move.

[0007] The pieces of material to be analyzed and sorted are fed into the chute by a feeding means according to the patent application WO 2007 / 024990. Under the influence of gravity, the pieces of material slide down the chute and exit the chute via the lower edge of the chute. From here, the pieces of material to be analyzed and sorted continue to fall freely under gravity through the ambient atmosphere. The feeding means and the chute function to separate the pieces of material and move them in free fall through a spatially defined falling path.

[0008] Laser-induced plasma spectroscopy is performed on each piece of material exiting the chute during free fall. To this end, a laser device is provided that is configured to generate a plasma on the surface of the piece of material by a laser beam propagating along a beam axis. Further, a spectrometer system is provided that is designed to perform a spectral analysis of the plasma light emitted by the laser-induced plasma and generate an output signal in accordance with the results of the spectral analysis performed.

[0009] This output signal is then used in combination with a sorting criterion in a sorting unit to separate the pieces of material leaving the chute into one of two fractions. For example, an air nozzle controlled accordingly by a control device can be used as the sorting unit. In this way, certain pieces of material can be removed from the stream of pieces of material leaving the chute under the influence of air pressure. As a result, there is one fraction of sorted pieces of material and one fraction of unsorted pieces of material.

[0010] Typically, known systems are used to identify pieces of material of a particular composition and separate them from pieces of material of a different composition. Such separation occurs either because the pieces of material of an undesired composition are identified by the sorting unit and rejected, or because the composition of the pieces of material cannot be reliably determined and therefore rejected by the sorting unit. The rejected pieces of material consist, on the one hand, of undesired pieces of material whose composition is clearly identified, and, on the other hand, of pieces of material whose composition is not clearly identified.

[0011] Although the above-described system has been shown to be in daily practical use, there is room for improvement. In particular, it has been found that for effective sorting results, it is important that the material pieces to be sorted are fed to the laser device and / or spectrometer system in individualized form so that the laser device and / or spectrometer system can access them in an optimized manner as the process continues. Otherwise, the sorting results will be adversely affected, in particular resulting in the unfavorable rejection of material pieces that are not clearly identified. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] European Patent No. 3352919 [Patent Document 2] West German Utility Model Publication No. 9106292 [Patent Document 3] International Publication No. 90 / 11142 [Patent Document 4] European Patent Application Publication No. 2859963 Summary of the Invention [Problem to be solved by the invention]

[0013] Based on the prior art, the object of the present invention is therefore to further develop a system of the initially mentioned kind in terms of design in order to achieve a high sorting efficiency. [Means for solving the problem]

[0014] To achieve this goal, a system of the kind mentioned at the beginning is proposed, which: the inclination angle of the supply surface of the first supply unit in the conveying direction is smaller than the inclination angle of the supply surface of the second supply unit in the conveying direction; The inclination angle of the supply surface of the second supply unit in the transport direction is smaller than the inclination angle of the supply surface of the third supply unit in the transport direction.

[0015] According to Patent Document 1, a feeding means is used to transport the material pieces, which provides a feeding surface along which the material pieces are moved in the intended use. The feeding means can be designed, for example, as a vibrating plate. In particular, the vibrating plate serves to separate the material pieces fed onto the feeding means, so that the material pieces can then be fed to the laser device and / or spectrometer system at a distance from each other.

[0016] However, the singulation achieved by the feeding means known from US 2007 / 0129998 is limited, which means that only relatively low throughput rates are possible. In this case, the throughput rate cannot be simply increased by feeding more pieces of material to be sorted into the feeding means, as this would result in insufficient singulation and, as a result, a lower sorting quality and therefore a lower sorting efficiency. The design according to the present invention provides a remedy here.

[0017] The supply means comprises three or more supply units, each designed as an independent assembly. Three or more separate (i.e. individual) supply units are thus provided, which are arranged one behind the other in succession in the conveying direction of the material pieces, so that there is a first supply unit in the conveying direction, a second supply unit in the conveying direction and a third supply unit in the conveying direction. These supply units together form the supply means according to the invention.

[0018] Each of the feed units is designed to transport pieces of material along a feed surface provided by the respective feed unit, and thus each feed unit provides a feed surface, and in intended use, the pieces of material are transported in a conveying direction and passed from feed unit to feed unit.

[0019] The feed surfaces of the feed units are each inclined at a respective angle of inclination relative to the horizontal, so that the feed units or their feed surfaces are inclined at an angle relative to the horizontal such that the pieces of material are supported while being conveyed in the conveying direction by the influence of gravity.

[0020] The feed units each provide, for example, a vibrating plate to provide a respective feed surface. As a result of the vibrating motion of such a plate, the material pieces thereon are transported in the transport direction. The inclined alignment of the respective feed surfaces as provided in the present invention supports this transport, as the force of gravity acting on the material pieces is added to the vibrating motion.

[0021] In this case, it is also provided that the inclination angles of the feed surfaces are designed to be different, as a result of which the gravity acting on the material pieces has a different effect on the transport of the material pieces in the transport direction depending on the feed unit, the greater the inclination angle.

[0022] The different inclination angles also have the advantageous effect of accelerating the material pieces in the conveying direction to different degrees depending on the supply unit. This allows for much more efficient singulation of a much larger number of material pieces, even when a large number of material pieces are being singulated. This is because the different angles of the supply surfaces of the individual supply units ensure that the conveying speed of the material pieces increases with increasing conveying distance, which in turn increases the singulation efficiency with increasing conveying distance. As a result, the laser device and / or spectrometer system can be reliably supplied with singulated material pieces, even when the number of material pieces to be separated increases compared to the prior art. Therefore, the supply means of the present invention ensures an increased flow rate while simultaneously improving the sorting quality, thereby improving the overall sorting efficiency of the system of the present invention compared to the prior art.

[0023] According to the invention, the inclination angle of the supply surface of the first supply unit in the conveying direction of the material pieces is designed to be smaller than the inclination angle of the supply surface of the second supply unit in the conveying direction of the material pieces. Due to gravity, the material pieces are accelerated to a higher transport speed by the second supply unit. This results in individualization of the material pieces, particularly in the longitudinal direction of the supply unit, i.e., in the conveying direction of the material pieces.

[0024] The relatively low conveying speed achieved by the first supply unit serves to separate the supplied material pieces, particularly across the width of the supply unit, i.e., transverse to the conveying direction of the material pieces. This ensures homogenization of the supplied material pieces across the width, so that the sorting devices through which the material pieces pass in further processing can function equally. In particular, this advantageously prevents individual sorting units from being supplied with too many material pieces to achieve the desired sorting quality, while other sorting units provide unused processing capacity. Therefore, the first supply unit is used to distribute the material pieces across the entire available width of the supply means.

[0025] The relatively low speed of the material pieces in the conveying direction provided by the first supply unit for widthwise distribution of the material pieces causes some accumulation of the material pieces in the conveying direction. This accumulation is eliminated after the material pieces are transferred from the first supply unit to the second supply unit because the second supply unit is inclined at a greater angle than the first supply unit. This allows the material pieces supplied to the second supply unit to be separated in the longitudinal direction, i.e., in the conveying direction of the material pieces.

[0026] The invention also provides that the angle of inclination of the supply surface of the second supply unit in the conveying direction of the material pieces is smaller than the angle of inclination of the supply surface of the third supply unit in the conveying direction of the material pieces.

[0027] The steeper inclination of the third supply unit compared to the second supply unit results in further acceleration of the material pieces in the conveying direction. The material pieces already singulated in the conveying direction by the second supply are separated further in the conveying direction and thus singulated by the third supply unit. This second stage of longitudinal singulation allows a larger number of material pieces to be processed by the supply means compared to the prior art. In this process, widthwise singulation is performed by the first supply unit, and longitudinal singulation is performed by the two additional supply units, resulting in singulated material pieces being fed longitudinally across the entire width of the supply means on the output side of the laser device or spectrometer system. This enables spectroscopy according to the intended purpose and, in contrast to the prior art, allows spectroscopy at an increased flow rate.

[0028] According to another feature of the invention, the difference between the tilt angles is between 2° and 8°, preferably between 3° and 7°, most preferably 5°. Studies have shown that the individual inclination angles cannot be selected completely freely. On the one hand, the angle must be steep enough to allow the acceleration of the material pieces according to gravity, especially in the longitudinal direction, in order to separate the pieces. However, on the other hand, the angle must not be selected too steep, as this would cause the material to step over and / or cause an overtaking effect, which would contradict the desired separation. The above-mentioned angle range is optimal according to the applicant's studies, and a difference between the inclination angles of 5° is selected in particular.

[0029] According to a further feature of the invention, the inclination angle of the supply surface of the first supply unit in the conveying direction of the material pieces is between 7° and 13°, preferably between 8° and 12°, most preferably 10°. This angle selection ensures that the material pieces fed to the supply unit are sufficiently accelerated in the conveying direction, while at the same time still achieving the desired distribution of the material pieces in the width direction. A too steep inclination angle has the disadvantageous effect of preventing the desired distribution of the material pieces in the width direction.

[0030] According to a further feature of the invention, it is provided that the angle of inclination of the feed surface of the second feed unit in the conveying direction of the material pieces is between 12° and 18°, preferably between 13° and 17°, most preferably 15°.

[0031] After the material pieces are transferred from the first feed unit to the second feed unit, they are accelerated in the conveying direction in order to separate the material pieces in the longitudinal direction of the feed unit, i.e., the conveying direction. In the first step, it is important to perform preliminary separating of the material pieces while avoiding the overtaking effect. A 10° inclination angle has been shown to be particularly suitable for achieving this desired separating. A steeper angle does not result in greater separating, but rather in the accumulation of unwanted material, particularly due to overtaking pieces and / or the overtaking effect.

[0032] According to a further feature of the invention, the angle of inclination of the feeding surface of the third feeding unit in the conveying direction of the material pieces is between 17° and 23°, preferably between 18° and 22°, most preferably 20°.

[0033] The pieces of material previously separated by the second supply unit can now be separated even further by the third supply unit, whereby a further inclination relative to the third supply unit is also possible while avoiding material jumping and / or overtaking effects, since the pieces of material have already been pre-accelerated by the second supply unit. The third supply unit also serves to finally separate the pieces of material further as they leave the supply means in a defined manner and move towards the laser device and / or spectrometer system.

[0034] In contrast to the prior art, the three-stage design of the feeding means according to the invention allows, on the one hand, an increase in the amount of material pieces to be processed, and, on the other hand, ensures a uniform distribution in the width direction and singulation in the conveying direction, in which the individual stages are coordinated with one another with respect to their respective tilt angles in such a way that the material pieces to be singulated are further accelerated from stage to stage, i.e. from feeding unit to feeding unit, thereby reliably avoiding undesirable overtaking effects and / or overtaking material pieces.

[0035] According to a further feature of the invention, the tilt angle is designed to be adjustable. Adjustability of the tilt angle is particularly advantageous when material pieces of different sizes and weights are to be sorted, since it is particularly useful to be able to adjust the respective tilt angle in an optimized manner for the sorting task. In this way, the tilt angle of all feed units or only individual feed units can be set accordingly, in particular depending on the size and / or specific weight of the material pieces to be sorted.

[0036] According to a further feature of the invention, the first feeding unit in the conveying direction of the material pieces is a swinging conveyor with an unbalanced drive. The first feed unit in the conveying direction is used to separate the material pieces and distribute them widthwise. A swing conveyor with an unbalanced drive is sufficient for this purpose and is the preferred option due to its relatively low acquisition and maintenance costs.

[0037] According to a further feature of the present invention, the second and third feed units are preferably designed as oscillating conveyors with magnetic drives. In contrast to oscillating feeders with unbalanced drives, vibrating feeders with magnetic drives offer the advantage of continuous feeding, which means that the conveying speed in the conveying direction can be more precisely influenced. The magnetic drives also ensure that trailing motion of the material pieces is essentially eliminated. This allows for very precise control of the material conveyance, which means that the desired individualization of the material pieces can be targeted.

[0038] According to another feature of the invention, the detection unit comprises a further objective lens, the further objective lens having a further detection cone assigned to it, the further detection cone forming a further plasma detection area in a further overlap region with the laser beam, the objective lens being positioned and / or aligned with respect to each other such that the plasma detection area and the further plasma detection area are offset along the beam axis and together form an observation area of ​​the detection unit.

[0039] This design advantageously provides an enlarged detection area so that more material pieces can be reliably detected with respect to their composition, resulting in improved sorting results as false sorts are minimized. The result is a more efficient sorting process.

[0040] The enlarged detection area is achieved in contrast to the prior art by providing not only one objective lens but also multiple objective lenses, i.e. two or more objective lenses, however more than two objective lenses, e.g. three, four or more objective lenses, are preferred.

[0041] A plasma detection area is set for each objective lens. Thus, with four objective lenses, there are four plasma detection areas. According to the present invention, it is further provided that the objective lenses are arranged and / or aligned with each other so that the plasma detection areas are offset along the beam axis of the laser beam and together form an observation area of ​​the detection unit. In this case, the observation area represents the entire detection area made up of the individual plasma detection areas and is therefore significantly larger than in the prior art.

[0042] According to the prior art, the detection area is formed by only one plasma detection area of ​​the objective lens. Along the beam axis of the laser beam, such a plasma detection area typically extends over a distance of 8-10 mm. The configuration of the observation area of ​​the detection unit according to the present invention, consisting of individual plasma detection areas offset along the beam axis, results in an overall detection area extending over 20 mm, 30 mm, 40 mm, or more along the beam axis. Due to their geometrical design, this has the advantageous effect of reliably detecting undetectable material pieces, including in particular spherical or partially spherically shaped material pieces.

[0043] As a result, the system according to the present invention allows for improved sorting, as the proportion of rejected pieces of material that are rejected because their composition cannot be reliably identified is minimized.

[0044] The design of the supply means according to the present invention, on the one hand, and the provision of a detection unit with an additional objective lens, on the other hand, result in a synergistic effect of an overall increase in throughput. The supply means according to the present invention can process more material pieces than the prior art, but a detection unit adapted to this is also required. On the other hand, the detection unit with the additional objective lens is not fully utilized if the supply means is unable to provide a corresponding amount of material pieces individually. Therefore, the combination of the supply means designed according to the present invention, on the one hand, and the further developed detection unit, on the other hand, ensures an overall even increased flow rate.

[0045] According to a further feature of the present invention, it is provided that the plasma detection area is configured such that when plasma is present in the plasma detection area, a measurement component of the plasma light is detected by the associated objective lens. Thus, when laser-induced plasma is at least partially present in the plasma area, a measurement component of the emitted plasma light is detected by the associated objective lens. According to the present invention, when multiple objective lenses are present, this means that the detection unit can detect the plasma light in the form of measurement components of the individual objective lenses.

[0046] According to a further feature of the invention, the plasma detection areas are arranged so that they are contiguous or spaced apart from one another along the beam axis. Alternatively or additionally, each plasma detection area can extend along the beam axis over 1 / 10 to 1 / 4 of the observation area. Thus, it is possible to form the entire detection region by arranging the plasma detection areas accordingly, especially after a sorting task.

[0047] According to a further feature of the present invention, it is provided that the feeding means according to the present invention is configured to convey the pieces of material along the feeding surface to the top of the chute. According to this preferred embodiment, the pieces of material are fed into the feeding means. From there, they pass through the chute and are conveyed along the feeding surface of the feeding means to the top of the chute. When the pieces of material reach the chute, they descend the chute by gravity. The purpose of the chute is, inter alia, to align the pieces of material and transfer them into a defined drop path.

[0048] According to a further feature of the invention, it is provided that the sorting unit is associated with a lower edge of the chute opposite the upper part of the chute, the sorting unit being configured to direct pieces of material exiting the chute via the lower edge into one of two fractions.

[0049] According to this preferred embodiment, the pieces of material leave the chute by free fall and are subjected to analysis and sorting in free fall, for which purpose in particular a laser device and a spectrometer system are arranged heightwise below the lower end of the chute.

[0050] According to a further feature of the invention, it is provided that the detection unit carries a protective housing which surrounds the laser beam and the detection cone. A protective housing is provided that protects both the laser beam and the detection cone of the objective lens from the intrusion of unwanted dust or particles from outside, effectively minimizing dust-related variations in sorting efficiency and ensuring that the sorting efficiency remains at least the same over time.

[0051] The protective housing surrounds the laser beam and the detection cone. The laser beam and the detection cone are thus guided through a volumetric space provided by the protective housing. Thanks to the encapsulation provided by the protective housing, this volumetric space is largely free of foreign particles, particularly dust particles and / or similar contaminants, so that neither the laser beam nor the detection cone are impaired in their functionality. Furthermore, the protective housing advantageously ensures that dust or other foreign particles do not unintentionally accumulate, particularly on optical components, thereby minimizing the risk of lens defects caused by such particles being burned into the lens.

[0052] Thus, on the one hand, the protective housing ensures that the internal spatial volume provided by the protective housing and traversed by both the laser beam and the detection cone is kept largely free of dust or similar foreign particles, and on the other hand, it ensures that dust or other foreign particles do not accumulate on the optical components or clog the passage openings, thereby ensuring a sorting efficiency that is at least constant over time, even if it does not increase, in a constructionally simple and therefore cost-effective manner.

[0053] According to a further feature of the invention, the protective housing extends along the beam axis of the laser beam. The protective housing is arranged on the detection unit, and is therefore supported by the detection unit, and extends from the detection unit in the direction of the longitudinal axis of the laser beam, and thus along the beam axis. The laser beam, and thus also the detection area of ​​the objective lens, is surrounded by the protective housing, which provides reliable shielding against dust or other foreign particles for both the objective lens and the path of the laser beam.

[0054] According to a further feature of the invention, it is provided that the protective housing extends over a portion of the distance between the detection unit and the plasma detection area. The plasma detection area is outside the protective housing; otherwise, proper material detection would be impossible. In order to guide both the laser beam and the detection cone to the plasma detection area with as few dust or foreign particles as possible, the protective housing extends over at least a portion of the distance between the detection unit and the plasma detection area. However, the protective housing preferably extends to the plasma detection area so that the entire portion between the detection unit and the plasma detection area is covered by the protective housing as much as possible.

[0055] According to another feature of the present invention, the protective housing is a truncated conical pipe section. Therefore, the protective housing is designed as a pipe that tapers on the plasma detection side. This taper has two advantageous effects. First, the protective housing is large enough on the detection unit side to completely accommodate the optics provided by the detection unit on the one hand and the passage opening for the laser provided by the detection unit on the other. Therefore, the entire optics and the passage opening are covered by the protective housing and thus protected from undesirable external influences.

[0056] As a result of the tapering of the protective housing in the direction of the plasma detection area, an exit opening is provided that is as small as possible, but still large enough so that the laser beam and detection cone are formed in the plasma detection area in the desired manner, i.e., are not affected by the protective housing. In this case, the exit cross-section of the protective housing is designed to be as small as possible to minimize unwanted dust or foreign particles entering the protective housing through the exit opening. In this case, the exit opening preferably has a diameter of 9 mm to 13 mm, preferably 10 mm to 12 mm, and even more preferably 11 mm.

[0057] According to another feature of the invention, it is provided that the protective housing is connected to a compressed air source on the laser beam incident side. The compressed air supply fills the protective housing with air and allows the air to pass through the protective housing, where air is supplied to the protective housing on the laser beam inlet side such that the air passes through the protective housing in the direction of laser beam propagation and exits the protective housing via the outlet opening.

[0058] Flushing the protective housing with air has two main advantages. First, any dust or other foreign particles that may enter the protective housing through the outlet opening are blown away by the compressed air, keeping the protective housing completely free of unwanted dust or foreign particles. On the other hand, on the outlet side, an air column is formed around the laser beam. This also keeps the plasma detection area free of dust or other foreign particles, meaning that the laser beam can be used to access the material pieces to be sorted without any dust particles. This optimizes laser detection and further improves the sorting efficiency of the system according to the present invention.

[0059] According to a further feature of the invention, the protective housing is made of a material that provides an inner surface that significantly reduces reflections. Plastic is a particularly suitable material, since, unlike metal, it does not provide a glossy surface. Stray light penetrating the protective housing from the outside is absorbed to the greatest extent possible, optimizing the utilization of the lens, since the effects of stray light do not impair the operation of the lens.

[0060] According to a further feature of the present invention, it is proposed to roughen the inner surface of the protective housing. This roughening ensures that any stray light effects result in diffuse reflection, which helps maximize light absorption. Therefore, both the selection of materials and the design of the inner surface advantageously ensure that further increases in efficiency are achieved by avoiding any obstruction of the optical system by stray light. The protective housing of the present invention thus synergistically provides two benefits: on the one hand, the effects of dust or other foreign particles are minimized, and on the other hand, the optical system is shielded from stray light. As a result of the design of the present invention, not only can consistent sorting efficiency and quality be guaranteed over time, but also, in contrast to prior art, sorting efficiency and quality are improved. Therefore, in contrast to prior art, the system of the present invention allows for increased throughput.

[0061] According to a further feature of the invention, it is provided that the sorting unit has a compressed air nozzle with an outlet opening of more than 3 mm, the compressed air nozzle being positioned at a distance from the laser beam generated by the laser device in the direction of movement of the material pieces passing through the laser beam, and the distance between the laser beam and the center of the outlet opening of the compressed air nozzle being less than 10 mm.

[0062] The compressed air nozzle of the sorting device is used to implement the piece recognition carried out by the detection unit, whereby pressure is applied to the piece of material identified by the input unit, and the identified piece of material is ejected as a result of this pressure application. Compressed air nozzles used according to the prior art typically have an outlet opening diameter of 3 mm. Here, the present invention proposes to choose a significantly larger outlet diameter, in any case more than 3 mm.

[0063] Furthermore, the present invention provides that the distance between the compressed air nozzle and the laser beam is reduced to less than 10 cm, in contrast to the prior art, where the distance between the laser beam and the compressed air nozzle is typically 10 cm or more.

[0064] In combination with the enlarged outlet opening diameter on the one hand and the enlarged distance between the laser beam and the compressed air nozzle on the other hand, an increased throughput of the material pieces to be sorted is advantageously achieved in contrast to the prior art.

[0065] With a typical drop velocity of the material pieces to be sorted and a nozzle opening time of 30 ms, as provided by the prior art, the material pieces to be sorted need to be fed into the sorting unit at a distance of at least 9 cm for optimal sorting to occur. As soon as the distance between the individual material pieces decreases to less than 9 cm, the individual material pieces can no longer be cleanly impacted by the compressed air nozzle, resulting in a decrease in sorting quality.

[0066] The design of the present invention offers a solution. In contrast to the prior art, the present invention provides for a reduction in the distance between the laser beam on the one hand and the compressed air nozzle on the other hand, i.e., the distance between the laser beam and the center of the compressed air nozzle's outlet opening, selecting a distance of less than 10 cm. This reduction in distance ensures that the pieces of material falling freely toward the laser beam do not approach each other, allowing them to be singulated at a reduced distance. Since the reduction in distance minimizes the fall distance, the fall time is also reduced, and as a result, the distance maintenance associated with the preceding singulation is not significantly affected by the free fall in the direction of the laser device. As a result, the distance maintenance selected for the singulation of the pieces of material can be reduced, thereby enabling higher throughput.

[0067] As already mentioned, the distance between individual pieces of material resulting from singulation can be reduced, thereby shortening the switching time for the compressed air nozzle. This allows the outlet opening diameter to be enlarged, in contrast to the prior art, resulting in a larger effective range for the compressed air nozzle. However, unlike the prior art, this increased effective range does not result in the application of compressed air also ejecting adjacent pieces of material that are not intended to be ejected, since the reduced distance can reduce the switching time for the compressed air nozzle. However, enlarging the outlet opening diameter allows for more reliable detection and therefore ejection of ejected pieces of material. As a result, in combination with the two features of the present invention, a synergistic effect results in both improved ejection quality on the one hand and increased throughput on the other hand. As a result, sorting efficiency can be significantly increased, in contrast to the prior art.

[0068] According to the prior art, it has been assumed that the outlet diameter of the compressed air nozzle should be selected as small as possible, i.e., 3 mm or less. This is to ensure that only the ejected material pieces are exposed to the compressed air, and that, for example, material pieces adjacent to the ejected material pieces are not exposed to the compressed air. It was not recognized that the outlet diameter of the compressed air nozzle and the distance between the compressed air nozzle and the laser beam are related in such a way that increasing the outlet diameter of the compressed air nozzle allows the distance between the laser beam and the compressed air nozzle to be reduced. This is because reducing the distance between the compressed air nozzle and the laser beam minimizes the catch-up and / or overtaking effect on the free-falling material pieces, so that there is no risk of capturing material pieces adjacent to the ejected material pieces, despite the enlarged outlet diameter. However, the enlarged outlet diameter allows for more reliable capture of the ejected material pieces, which, combined with the reduced distance between the compressed air nozzle and the laser beam, results in increased throughput rates and improved sorting quality, in contrast to the prior art.

[0069] According to a further feature of the invention, the diameter of the outlet opening is between 5 mm and 8 mm, preferably between 6 mm and 7 mm, most preferably 6.5 mm. As the applicant's research has shown, the diameter of the outlet opening can be significantly larger than 3 mm. The size of the outlet opening diameter is optimized depending on, on the one hand, the distance between the compressed air nozzle and the laser beam, and, on the other hand, the size of the material being sorted. In this regard, an outlet opening diameter of 6 to 7 mm is particularly preferred.

[0070] According to a further feature of the invention, it is provided that the distance between the laser beam and the center of the outlet opening of the compressed air nozzle is between 8 cm and 3 cm, preferably between 6 cm and 3.5 cm, even more preferably between 5 cm and 4 cm, and most preferably 4.5 cm.

[0071] The reduced distance between the laser beam and the center of the compressed air nozzle's outlet opening, as opposed to the prior art, offers the advantages already mentioned. In this case, the applicant's research has shown that by selecting a correspondingly appropriate outlet opening diameter for the compressed air nozzle, this distance can be significantly reduced, as opposed to the prior art. The shorter the distance between the laser beam and the compressed air nozzle, the less likely it is that pieces of material falling freely toward the laser beam will be trapped or overtake each other. If the pieces of material are sufficiently separated, the distance between two consecutive pieces is such that when compressed air is applied to the compressed air nozzle to eject one piece of material, the adjacent piece of material to be ejected will not be trapped either. As a result, sorting quality is improved, as incorrect ejection of pieces of material despite clear identification is particularly prevented.

[0072] According to a further feature of the invention, it is provided that the sorting unit comprises a solenoid valve cooperating with the compressed air nozzle, the compressed air nozzle and the solenoid valve being arranged structurally separate from each other.

[0073] Structural separation of the compressed air nozzle and the solenoid valve allows for optimized use of the space available in the immediate vicinity of the laser device, so that the distance between the compressed air nozzle and the laser beam generated by the laser device in intended use is as small as possible. Spatial separation of the compressed air nozzle and the solenoid valve also has the advantage that the space available in the immediate vicinity of the laser device is not unnecessarily wasted by also accommodating the solenoid valve. Rather, this space remains free so that the compressed air nozzle can be optimally aligned with its distance from the laser device.

[0074] According to another feature of the invention, the compressed air nozzle is fluidly connected to the solenoid valve by a compressed air line. The otherwise usual direct fluid connection between the compressed air nozzle and the solenoid valve is replaced according to this proposal of the invention by the compressed air line, which can be designed, for example, as a hose. This allows for a structural separation of the compressed air nozzle and the solenoid valve without impairing the intended function of the compressed air nozzle.

[0075] According to a further feature of the invention, the switching time of the solenoid valve is less than 30 ms, preferably less than 20 ms, and more preferably less than 10 ms. In contrast to the prior art, this reduced changeover time, made possible by the design according to the invention, results in significantly higher throughput: double or even triple the amount of material pieces can thus be sorted as intended per unit of time.

[0076] Further features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0077] [Figure 1] 1 is a schematic diagram of a system according to the present invention. [Figure 2] 1 is a schematic diagram of a supply means according to the present invention; [Figure 3] FIG. 4 is a further schematic diagram of the operation of the system according to the present invention. [Figure 4] 2 is an enlarged schematic view of a spectrometer system according to the system of the present invention shown in FIG. 1; [Figure 5] FIG. 2 is a further schematic diagram of the functionality of the LIBS module of the system according to the invention. [Figure 6] 6 is a schematic side view of a cross section of the module according to FIG. 5; [Figure 7] 1 is a partially cutaway side view of a protective housing according to the present invention; [Figure 8] 1 is a schematic diagram of a compressed air nozzle designed and arranged in accordance with the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0078] FIG. 1 shows a schematic representation of a system 100 according to the present invention. The system 100 is configured to apply laser-induced plasma spectroscopy to the pieces of material 120 and to sort the pieces of material 120 depending on the results of the spectral analysis, in the example shown providing two fractions F1 and F2 to which the pieces of material 120 can be allocated. Collection points 170, for example in the form of bins, serve to receive the respective fractions F1 and F2.

[0079] As can be seen from the schematic diagram according to Figure 1, the system 100 comprises a feed means 110 followed by a chute 130. In intended use, pieces of material 120 are fed to the feed means 110. The feed means 110 functions to transport the pieces of material 120 along a feed surface 111 provided by the feed means, i.e., up to the top 131 of the chute 130, where the pieces of material 120 are transferred from the feed means 110 to the chute 130.

[0080] The supply means 110 is used in particular to separate the multiple pieces of material 120 arranged on the supply means 110, so that the multiple pieces of material 120 can be supplied to the chute 130 at a distance from each other.

[0081] The pieces of material 120 transferred to the chute 130 slide down the chute 130 under gravity to a lower edge 132 of the chute, which is designed to face the upper portion 131 of the chute 130. The task of the chute 130 is, inter alia, to align and transfer the pieces of material 120 within a defined falling path.

[0082] After leaving the chute 130, the material pieces 120 continue to move under the influence of gravity in free fall through the surrounding atmosphere. In doing so, they pass through the spectrometer system 1, which ensures an analysis of the material pieces 120, as will be explained in more detail below. According to the results of the performed spectral analysis, the spectrometer system 1 generates an output signal. This is supplied to the control device 150, which operates, i.e., drives, the sorting unit 160 depending on the output signal, on the one hand, and on the sorting criteria, on the other hand. The sorting unit 160 either deflects the material pieces 120 in free fall or does not deflect them. If no deflection occurs, the material pieces 120 reach the collection point 170 for fraction F2. Otherwise, if sorting by the sorting unit 160 occurs, the material pieces 120 reach the collection point 170 for fraction F1.

[0083] Spectrometer system 1, which is part of LIBS module 180, is used to analyze the composition of material piece 120. LIBS module 180 also includes laser device 140 and control device 150. Preferably, laser device 140, spectrometer system 1, and control device 150 are housed in a common housing, which is not shown in detail in FIG.

[0084] The laser device 140 itself consists of further individual components, such as a laser beam source 9, an optical fiber 9A, and focusing optics 11, as can be seen particularly in the example shown in FIG.

[0085] The supply means 110 is designed according to the invention in three stages, as can be seen from the diagram in FIG. In the example shown, the feeding means 110 comprises three separate feeding units 201, 202 and 203, which are arranged one behind the other in a conveying direction 207 of the pieces of material 120. Each feeding unit 201, 202 and 203 provides a feeding surface 204, 205 and 206, respectively, along which the pieces of material 120 move in intended use.

[0086] The feed surfaces 204, 205 and 206 are each inclined at respective inclination angles α1, α2 and α3 with respect to the horizontal, which are designed to be different in size according to the present invention.

[0087] Overall, the supply units 201, 202 and 203 form the supply means 110. The supply surface 111 provided by the supply means 110 is subdivided into supply surfaces 204, 205 and 206 of the supply units 201, 202 and 203.

[0088] In intended use, the supply means 110 is supplied with material pieces 120 by a conveyor 200 which may be designed, for example, as a belt conveyor. From the conveyor 200, the material pieces 121 reach a first supply unit 201 in the conveying direction 207. This supply unit 201 is designed, for example, as a vibrating conveyor with an unbalanced drive and is primarily used to distribute the supplied material pieces 120 widthwise, i.e. transversely to the conveying direction 207.

[0089] The feed surface 204 of the first feed unit 201 is inclined at an inclination angle α1 of, for example, 10°. As a result, the material pieces are conveyed in a conveying direction 207 by gravity. The material pieces then move from the first supply unit 201 to a second supply unit 202 arranged downstream of the first supply unit 201 in the conveying direction 207. The supply surface 205 provided by the second supply unit 202 is at an inclination angle α2 that is greater than the inclination angle α1, for example 15°. This steeper inclination angle α2 ensures that a higher conveying speed of the material pieces 120 in the conveying direction 207 is achieved by gravity. As a result, the material pieces 120 are singulated in the conveying direction 207.

[0090] From the second supply unit 202, the material pieces 120 finally reach a third supply unit 203, whose supply surface 206 is inclined at an inclination angle α3 to the horizontal. The inclination angle α3 is greater than the inclination angle α2 of the second supply surface 205, e.g., 20°. This steeper inclination angle α3 causes a further acceleration of the material pieces 120, which results in a higher velocity of the material pieces 120, and as a result, further singulation in the conveying direction 207.

[0091] Finally, the material pieces 120 are singulated in the conveying direction 207 after passing through the feed unit 203 into the chute 130 so that they can be sorted in the manner already described.

[0092] As can be seen in particular from Figure 3, the spectrometer system 1 comprises a detection unit 21, which serves several purposes. A detection cone 35 is assigned to each of these objective lenses, which in the area of ​​overlap with the laser beam 5 form in each case a plasma detection area 39. These plasma detection areas 39 are arranged offset from one another along the beam axis of the laser beam 5 and together form an observation region 41 of the detection unit 21. The observation region 41 is therefore made up of the individual plasma detection areas 39, thereby defining the detection area that is entirely covered by the detection unit.

[0093] Figure 3 shows a schematic overview of a spectrometer system 1 for spectral analysis of plasma light 3A emitted by a laser-induced plasma 3 (schematically shown as a black circle). The detectable plasma light 3A may be, for example, in the UV, visible, near-infrared, and / or infrared wavelength ranges; in particular, the detectable plasma light may be in the spectral range from about 190 nm to about 920 nm. In the case of LIBS, the plasma 3 is generated by a laser beam 5 on the surface 7A of a sample 7.

[0094] The spectrometer system 1 includes a laser beam source 9, e.g., for generating a pulsed laser beam 5. The laser beam source 9 is designed to provide the laser beam parameters required for plasma generation. The laser beam 5 is fed, for example, via an optical fiber 9A of a focusing optics 11 and focused onto the surface 7A of the sample 7 (piece of material 120 according to FIG. 1). The focusing optics 11 can be designed as a laser head component with a focusing function, such as an active laser component with a focusing function that specifically affects the spectrum, pulse duration, or pulse energy. The laser beam 5 propagates along a beam axis 5A between the focusing optics 11 and the sample 7. Exemplary focal diameters (1 / e2 beam diameter at the beam waist) and focal lengths (twice the Rayleigh length) are in the range of <50 μm to >250 μm or <5 mm to >1000 mm, respectively.

[0095] In particular, the laser parameters may be set / selected so that the range in which plasma generation can occur (also called the ignition range) extends along the beam axis 5A over a length in the range of, for example, about 5 mm to about 50 mm, for example over a length of 10 mm, 20 mm or 30 mm.

[0096] 3 shows schematically an elongated focal zone 11A along the beam axis 5A as it is formed in the area of ​​the surface 7A of the sample 7. A plasma 3 is formed by the interaction of the laser radiation with the material at the surface of the sample 7A. In LIBS, typical dimensions (average diameter) of the plasma 3 are, for example, in the range of 0.1 mm to 5 mm (depending on the sample material and the laser parameters).

[0097] The spectrometer system 1 also includes an optical spectrometer 13 for spectral analysis of the plasma light 3A. The optical spectrometer 13 is shown in FIG. 2 as an example of a grating spectrometer. Typically, the spectrometer 13 includes one or more dispersive elements 13A, such as a grating, prism, or grating prism, and a pixel-based detector 13B onto which the plasma light is incident in a spectrally expanded form. The spectral components of the plasma light 3A to be analyzed are assigned to pixels of the detector 13B. The detector 13B outputs intensity values ​​of the illuminated pixels to an evaluation unit 15, typically a computer with a processor and memory. The evaluation unit 15 outputs the measured spectral distribution 17 and compares it with, for example, a stored reference spectrum to assign the components contributing to the plasma light 3A, and thus to the sample 3 being tested, and outputs them as the results of the spectral test.

[0098] In the spectrometer 13, the (spectral dependent) beam entrance for the plasma light to be analyzed is defined by an entrance aperture 19, typically an entrance slit 19A. The spectrometer system 1 further comprises a detection unit 21 having an objective lens holder 23 and several objective lenses 25A, 25B, 25C supported by the objective lens holder 23. By way of example, three objective lenses are shown in the figure: two in the image plane and one behind it. The number of objective lenses used can be selected depending on the spatial and optical parameters as well as the material parameters of the sample being examined and can lie in the range of 2 to 20, e.g., 4, 5, 8, 9 or 15 objective lenses.

[0099] The spectrometer system 1, in particular the detection unit 21, further comprises an optical fiber system 27 optically connecting the objective lenses 25A, 25B, 25C to the spectrometer 13. The optical fiber system 27 provides several optical inputs 29, each optically assigned to one of the objective lenses 25A, 25B, 25C, and an optical output 31 (functional and common to the objective lenses) optically assigned to the entrance aperture 19.

[0100] Each of the objective lenses 25A, 25B, and 25C is configured to detect a measurement component 33 of the plasma light 3A and includes one or more focusing optical elements, such as a converging lens or a concave mirror. A detection cone 35 is assigned to each of the objective lenses 25A, 25B, and 25C. The beam axis 5A extends through the detection cone 35, and the detection cone 35 has a set minimum size in the region of the laser beam 5. Each of the detection cones 35 encompasses a plasma detection area 39 in the region of overlap with the laser beam 5, and this plasma detection area 39 is assigned to the corresponding objective lens 25A, 25B, and 25C. For example, the detection cone 35 has a length of the objective lens' entrance aperture relative to the laser beam in the range of 200 mm to 400 mm. 2, plasma 3 is generated in plasma detection area 39 of objective lens 25B such that associated measurement components 33 of plasma light 3A are detected by objective lens 25B and imaged onto associated optical inputs 29 of fiber optic system 27. Measurement components 33 captured by one or more objective lenses are directed by optical light guiding system 27 to a common optical output 31 and coupled through entrance aperture 19 to optical spectrometer 13 for spectral analysis.

[0101] FIG. 3 shows, as an example, three objective lenses 25A, 25B, and 25C, which are azimuthally dispersed around the beam axis 5A. Objective lenses 25A and 25B are located on either side of the beam axis 5A and are therefore directed toward the beam axis 5A from both sides. Objective lens 25C is directed toward the beam axis 5A from the rear. Another objective lens (not shown in FIG. 2) can be directed onto the beam axis 5A from the front, for example, or along the beam axis 5A onto the focal zone 11A using a beam splitter. For clarity, the detection cone 35 is shown in FIG. 2 as extending conically relative to the beam axis 5A, and the focal zone 11A, plasma 3, and plasma detection area 39 are shown enlarged relative to the detection cone 35 for clarity.

[0102] FIG. 4 shows a detailed view of the system 100 according to the invention, again according to FIG. 1. Here, it can be seen that pieces of material of different compositions are provided, namely plastic pieces 120B and aluminum pieces 120A. As already explained, the spectrometer system 1 according to the invention can be used to separate the pieces 120A from the pieces 120B. For this purpose, the sorting unit 160 ejects the plastic pieces 120B if they are detected. For this purpose, the sorting unit 160 has a pneumatic nozzle 400 by means of which the plastic pieces 120B can be ejected from the flow of pieces. As a result of such separation, the plastic pieces 120B and the aluminum pieces 120A accumulate separately at a collection point 170.

[0103] 4 shows the mounting plate 23A of the detection unit 21 of the LIBS system to clarify the placement and orientation of the objective lenses 25A, 25B, and 25C. To securely mount the objective lenses, the mounting plate 23A has objective lens holding holes for receiving the objective lenses 25A, 25B, and 25C. The objective lens holding holes are each positioned at a radial distance from the beam axis 5A and are designed to orient the objective lenses 25A, 25B, and 25C obliquely relative to the beam axis 5A.

[0104] 4, the plasma detection area 39 together form an observation region 41 of the detection unit 21. The observation region 41 extends along the beam axis 5A in the region of the focal zone 11A.

[0105] Additionally, in mounting plate 23A in FIG. 2, there is seen an optical passage opening 43 that is used to direct the laser beam through holder 23, through objective lenses 25A, 25B, 25C and onto sample 7.

[0106] Figure 5 shows a perspective view of an exemplary LIBS measurement head connected to a laser beam source via an optical fiber 9A. The LIBS measurement head's holder 23 includes a longitudinal support plate 23B, on which fixtures for the optical fiber 9A and focusing optics 11 (laser head with beam shaping) are provided at the input side. Furthermore, an optical spectrometer 13 is mounted on the longitudinal support plate 23B and is provided with a mounting plate 23A for four objective lenses 25A, 25B, 25C, and 25D (typically, n > 1 input optics). The objective lenses 25A, 25B, 25C, and 25D are designed to detect measurement components of the plasma light from plasma detection areas 39, which are offset from one another along the beam axis 5A, and to supply them to the spectrometer 13 for spectral analysis via an optical fiber system 27 (e.g., a fiber bundle with n > 1 inputs and one functional output—an "n-to-1 fiber bundle"). 3 shows an optical fiber 45 of the optical fiber system 27 optically connecting the objective lenses to a common spectrometer 13. The optical fiber system 27 can be used to combine measurement components at the spectrometer 13 (or optionally prior to coupling to the spectrometer 13) for measurement processing.

[0107] FIG. 6 shows a schematic side view of a part of the module according to FIG. 5, where the mounting plate 23A is provided with a protective housing 300 according to the invention. 6, the protective housing 300 is a frustoconical tube section that extends along the beam axis 5A of the laser beam 5, starting from the mounting plate 23A to the observation region 41, i.e., to the first plasma detection area 39 in the direction of propagation of the laser beam 5. The protective housing 300 substantially bridges the distance between the plasma detection area 39 and the mounting plate 23A in the longitudinal direction of the laser beam 5.

[0108] The protective housing 300 surrounds both the laser beam 5 and the detection cone 35 assigned to each of the objective lenses 25A to 25D. Thus, the laser beam 5 and the detection area 35 are surrounded by the protective housing 300.

[0109] The protective housing 300 essentially achieves two effects: First, the lenses 25A-25D, as well as the light passage opening 43 formed in the mounting plate 23A for the laser beam 5, are protected from the undesirable influence of dust and / or other foreign particles originating from the environment. This largely prevents undesirable influence of dust and / or other foreign particles on the lenses 25A-25D and the passage opening 43.

[0110] On the other hand, the volumetric space provided by the protective housing 300 and traversed by both the laser beam 5 and the detection cone 35 in intended use is also kept free of dust and / or other foreign particles, so that both the laser beam 5 and the detection cone 35 are not impaired in their intended function.

[0111] The protective housing 300 is connected to a compressed air unit, not specifically shown in the figures, by means of which compressed air can be supplied to the mounting plate side of the protective housing 900, which compressed air flows through the protective housing 300 in the direction of propagation of the laser beam 5. As a result of such air flow, any dust and / or other foreign particles are effectively prevented from entering the protective housing 300 via the outlet opening 303 of the plasma detection side of the protective housing 300.

[0112] Directing air at the protective housing 300 also has the advantage that an air cone or column 301 is formed on the exit side of the protective housing 300 surrounding the laser beam 5. This has the positive effect that the observation region 41, consisting of the plasma detection area 39, is also kept largely free of dust and / or other foreign particles.

[0113] 7 shows a detail of a protective housing 300 according to the invention in a partially cutaway side view. As can be seen in particular from this figure, the protective housing 300 is frusto-conical and provides on the output side an outlet opening 303, which is preferably circular in cross section and is traversed in its centre by the laser beam 5.

[0114] The protective housing 300 is preferably made of plastic with minimal or no reflective properties. Stray light entering the protective housing 200 through the exit opening 303 is absorbed to such an extent that the optical system covered by the protective housing 300 is not affected by the reflected stray light. In this case, it is also intended that the inner surface 303 of the protective housing 200 be roughened. This results in diffuse reflection of stray light that penetrates the protective housing and also helps to minimize undesirable obstructions of the lenses 25A-25D covered by the protective housing 300.

[0115] FIG. 8 shows only a schematic representation of the design and arrangement of a compressed air nozzle 400 according to the present invention. 8, the compressed air nozzle 400 is positioned at a distance from the laser beam 5 generated by the laser device 140 in the direction of movement 401 of the piece of material 120 passing through the laser beam 5. This distance A between the laser beam 5 and the center of the outlet opening 402 of the compressed air nozzle 400 is less than 10 cm. However, a distance A between 6 cm and 3.5 cm is preferred, and a distance between 5 cm and 4 cm is even more preferred.

[0116] According to the present invention, the opening diameter of the outlet opening 402 of the compressed air nozzle 400 is greater than 3 mm, preferably 6 mm to 7 mm, and most preferably 6.5 mm. The compressed air nozzle 400 is supplied with compressed air from a compressed air generator 405 .

[0117] The compressed air nozzle 400 is designed to be switchable, for which purpose a solenoid valve 403 is provided, which is fluidly connected on the one hand to a compressed air generator 505 via a line 406 and on the other hand to the compressed air nozzle 400 via a line 404.

[0118] The structural separation of the compressed air nozzle 400 and the solenoid valve 403 makes it possible to optimally use the installation space in the immediate vicinity of the laser device 140 in order to position the compressed air nozzle 400 as close as possible to the laser beam 5, i.e. to select the distance A as already explained. [Explanation of symbols]

[0119] 1. Spectrometer system 3. Plasma 3A Plasma Light 5 Laser beam 5A Beam axis 7. Sample 7A surface 9 Laser beam source 9A Optical Fiber 11 Focusing optical system 11 Focal Zone 13 Optical spectrometer 13A Dispersion Element 13B detector 15 evaluation units 17 Spectral Distribution 19 Entrance opening 19A Inlet gap 21 Detection unit 23 Objective lens holder 25A objective lens 25B objective lens 25C objective lens 25D objective lens 27 Optical Fiber Systems 29 Optical Input 31 Optical Output 33 Measurement Components 35 detection cone 39 Plasma detection area 41 Observation Area 100 systems 110 Supply means 111 Supply means 120 Material Piece 120A Aluminum part 120B Plastic part 130 shots 131 Upper 132 Lower edge 140 Laser Devices 150 Control Device 160 Sorting Unit 170 accumulation points 180 LIBS modules 200 Conveyor 201 Supply Unit 202 Supply Unit 203 Supply Unit 204 Supply side 205 Supply side 206 Supply side 207 Conveying direction 300 Protective Housing 301 Air column 302 Interior 303 Exit opening 400 Compressed Air Nozzle 401 Direction of movement 402 Exit opening 403 Solenoid valve 404 Line 405 Compressed Air Generator 406 Line α1 tilt angle α2 tilt angle α3 tilt angle

Claims

1. 1. A system for analyzing and sorting material pieces, in particular aluminum scrap pieces, comprising: a feeding means (110) for conveying said pieces of material (120); a sorting unit (160) configured to feed the pieces of material (120) into one of two fractions (F1, F2); a laser device (140) configured to generate a plasma (3) on a surface (7A) of the piece of material (120) using a laser beam (5) propagating along a beam axis (5A); a spectrometer system (1) configured to perform a spectral analysis of plasma light (3A) emitted by the laser-induced plasma (3) and to generate an output signal according to the results of the performed spectral analysis; a control device (150) configured to receive the output signal and operate the sorting unit (160) based on the output signal and sorting criteria; The spectrometer system (1) comprises an optical spectrometer (13) and a detection unit (21) optically connected to the optical spectrometer (13); the detection unit (21) has objective lenses (25A, 25B, 25C, 25D), each of which has a detection cone (35) assigned thereto, the detection cone (35) forming a plasma detection area (39) in an overlap region (37) with the laser beam (5); the feeding means (110) comprises three individual feeding units (201, 202, 203) arranged one behind the other in succession in the conveying direction (207) of the material pieces (120), each supply unit (201, 202, 203) is configured to convey the piece of material (120) along a supply surface (204, 205, 206) provided by the respective supply unit (201, 202, 203); The supply surfaces (204, 205, 206) are inclined with respect to the horizontal, and each of the inclination angles (α １ , α ２ , α ３ ) and The inclination angle (α １ , α ２ , α ３ ) are designed differently, The inclination angle (α １ ) is the inclination angle (α ) of the supply surface (205) of the second supply unit (202) in the conveying direction (207). ２ ) and is configured to be smaller than The inclination angle (α ２ ) is the inclination angle (α ) of the supply surface (206) of the third supply unit (203) in the conveying direction (207). ３ ) is configured to be smaller than the

2. The inclination angle (α １ , α ２ , α ３ 2. The system of claim 1, wherein the difference between the angles θ and θ is between 2° and 8°, preferably between 3° and 7°, and most preferably 5°.

3. The inclination angle (α １ 3. The system according to claim 1, wherein the angle θ is between 7° and 13°, preferably between 8° and 12°, most preferably 10°.

4. The inclination angle (α ２ 4. The system according to claim 1, wherein the angle θ is between 12° and 18°, preferably between 13° and 17°, most preferably 15°.

5. The inclination angle (α ３ 5. The system according to claim 1, wherein the angle θ is between 17° and 23°, preferably between 18° and 22°, most preferably 20°.

6. The inclination angle (α １ , α ２ , α ３ 6. The system according to claim 1, wherein the first and second electrodes are designed to be adjustable.

7. The system according to any one of the preceding claims, wherein the first feeding unit (201) in the conveying direction (207) is a vibrating conveyor with an unbalanced drive.

8. The system according to any one of claims 1 to 7, wherein the second supply unit (202) and the third supply unit (203) in the conveying direction are each oscillating conveyors with magnetic drives.

9. the detection unit (21) comprises further objective lenses (25A, 25B, 25C, 25D), each having a further detection cone (35) assigned to the further objective lenses (25A, 25B, 25C, 25D), the further detection cone (35) forming a further plasma detection area (39) in a further overlap region (37) with the laser beam (5); 9. The system of claim 1, wherein the further objective lenses (25A, 25B, 25C, 25D) are positioned and / or aligned with respect to each other such that the plasma detection area (39) and the further plasma detection area (39) are offset along the beam axis (5A) and together form an observation region (41) of the detection unit (21).

10. 2. The system of claim 1, wherein the plasma detection area (39) is configured such that when a plasma (3) is present in the plasma detection area (39), a measurement component (33) of the plasma light (3A) is detected by the associated objective lens (25A, 25B, 25C, 25D).

11. The system according to any one of claims 1 to 10, wherein the plasma detection areas (39) are arranged to be contiguous or spaced apart from one another along the beam axis (5A).

12. 3. The system of claim 1, wherein the objective lens holder (23) provides an optical passage opening (43) through which the beam axis (5A) extends.

13. 2. The system of claim 1, wherein the sorting unit (160) is assigned to a lower edge (132) of the chute (130), the lower edge (132) being opposite an upper portion (131) of the chute (130), and the sorting unit (160) is configured to feed the pieces of material (120) leaving the chute via the lower edge (132) of the chute (130) into one of two fractions (F1, F2).

14. 14. The system of claim 1, wherein the detection unit (21) carries a protective housing (300) surrounding the laser beam (5) and the detection cone (34), the protective housing (300) extending along the beam axis (5A).

15. 15. The system according to claim 1, wherein the sorting unit (160) comprises a compressed air nozzle (400) having an outlet opening diameter of more than 3 mm, preferably between 5 mm and 8 mm, the compressed air nozzle (400) being arranged at a distance from the laser beam (5) generated by the laser device (140) in the direction of movement (401) of the material pieces (120) passing through the laser beam (5), the distance between the laser beam (5) and the center of the outlet opening (402) of the compressed air nozzle (400) being more than 10 cm, preferably between 8 cm and 3 cm.

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