JP2012073080A - Aluminum alloy discrimination method and sorting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy discrimination method for each alloy system, and to provide an aluminum alloy sorting apparatus using the method.SOLUTION: The discrimination method comprises: plotting on a measurement plane the transmission X-ray intensity measurement results of a plurality of samples for calibration (a first aluminum alloy) to be collected and samples for comparison (a second aluminum alloy) to be removed for every unit area of X-rays with different energy; defining a discrimination belt sandwiching distribution of the measurement results of the samples for calibration with an upper side curve and a lower side curve; dividing the measurement plane into a medium density area, a higher density area, and a lower density area by the discrimination belt; deciding a first threshold value on the measurement results of the samples for calibration in the higher density area or the lower density area, compared with the distribution of the measurement results of the sample for comparison; deciding a second threshold value from the measurement results of the samples for calibration in the medium density area; and determining to be a collection object when a proportion including a transmission X-ray intensity measurement value for every unit area on a sorted sample in the higher density area or the lower density area is smaller than the first threshold value, and proportion including the measurement value in the medium density area is larger than the second threshold value.

Description

  The present invention relates to a method for discriminating an aluminum alloy by alloy system and an equipment for sorting, and in particular, not only selectively collects an aluminum alloy derived from a cast material and an aluminum alloy derived from a wrought material, but further adds the wrought aluminum alloy. The present invention relates to an aluminum alloy discrimination method and sorting equipment for sorting and collecting by system.

Aluminum is an extremely recyclable material, and the melting energy of secondary bullion by recycling is only 3 to 5% of the melting energy of new bullion. For this reason, by operating the recycling system efficiently, aluminum can be widely used as a material with low energy consumption and an environment-friendly material and a low manufacturing cost.
Even at present, aluminum or aluminum alloys are generally recycled from the viewpoints of resource saving and cost reduction. For this reason, conventionally, a technique has been developed in which aluminum and an aluminum alloy are sorted and recovered from other metals quickly and in large quantities.

  For example, Patent Document 1 discloses a relatively general metal sorting and collecting apparatus. The disclosed metal sorter crushes the waste stored in the stockyard after pretreatment, separates the foamed molding material, sends the remaining heavy waste to the metal sorter, and separates copper pieces or aluminum pieces. It is a system to separate. In the metal sorting apparatus, ferrous metals are separated by a magnetic sorter, and non-ferrous metals are sorted by an eddy current sorter. Further, for the non-ferrous metal, a copper piece and an aluminum piece are further sorted by a color sorter and a specific gravity detection sorter, respectively. Moreover, what was separated as a non-metal by an eddy current sorter separates a metal piece with a wind sorter, and collects a copper piece and an aluminum piece through a vibration type sorter.

According to the disclosed metal sorting and collecting apparatus, aluminum can be sorted and collected with high purity from waste almost automatically.
Patent Document 1 describes an example using an X-ray type sorter that uses the fact that X-ray transmission differs depending on the type of metal, instead of a color sorter. The disclosed X-ray sorter is provided with a shape sensor in front of the X-ray detection sensor, measures the thickness of the fragments, calculates the transmitted X-ray intensity per unit thickness, The material of the crushed piece is estimated by collating with the acquired data.

However, aluminum alloy has different additive element contents depending on the alloy type, but it could not be collected separately for each alloy type, so the recovered aluminum etc. was mixed and melted regardless of the alloy type, and the component composition It has been recycled as low-grade secondary alloys and cast alloys.
Cast materials reclaimed from aluminum recovered in this way have been mainly used for internal combustion engines of automobiles. Since the production volume of automobiles is large and the demand for aluminum alloy castings is large, the recovered aluminum and aluminum alloys have been sufficiently digested.

However, in recent years, automobile engines are gradually becoming petroleum-free fuel, and internal combustion engines are being replaced by electric motors, etc., and aluminum recycling may not be realized in the near future due to a decline in demand for casting materials.
In this way, when considering the future, recovered aluminum needs to cultivate customers other than automobiles. In order to expand demand, it is difficult to simply recycle as a casting material that relies on automobile demand, and it is necessary to be able to supply a recovered aluminum alloy derived from the wrought material as the wrought material.

  Aluminum alloys have alloy types that are determined by the composition of the metal added to the aluminum, and appropriate applications are determined for each alloy type, so if metals that become impurities for high-grade aluminum alloys are mixed, the quality will be reduced and recycled. It cannot be used for the intended aluminum alloy application. Conventionally, aluminum and aluminum alloys that have been selected and collected from waste materials are mixed together and recycled regardless of the alloy type. Therefore, casting materials that can be produced by adding elements that are lacking as components to the mixed aluminum alloy. I had no choice but to reuse it.

  For example, an aluminum alloy having an alloy number 6063 is a high-grade alloy with few additive components, and has excellent extension performance and is used as a spread material for sashes. Alloy No. 6063 is contained in a large amount in building waste as a detached window frame. However, even if a large amount of sash is recovered as waste, it is currently suitable to separate and collect the types of aluminum and aluminum alloys. Because there is no means, and because it is mixed with the castings that are recovered at the same time, there was no other way but to melt together and make a low-grade secondary alloy metal or cast material.

  Therefore, if aluminum and aluminum alloys in waste can be collected separately by alloy system, most of the recovered aluminum alloys will not be recycled as low-cost castings with limited future demand. Depending on the system, it can be reused as a material that can be expected to have a large amount of demand, such as a sash material.

  In addition, in the conventional recycling, in order to produce secondary alloy ingots from aluminum scrap, it is necessary to go through a melting process for component analysis and component adjustment, which consumes relatively large energy. When reusing waste as a sash material, if the foreign matter is sorted and removed from the sash waste and only the aluminum alloy for the sash can be made, the melting energy and the regeneration process of the secondary alloy ingot manufacturing process can be reduced. Significant savings.

For this reason, it is required to collect aluminum and aluminum alloys separately for each alloy system, for example, a sash wrought material and other wrought materials or cast materials. For this purpose, a method for distinguishing and determining aluminum and aluminum alloys by alloy system is required.
Conventionally, however, there is no appropriate method for making a distinction according to the alloy system, and various aluminum and aluminum alloys in general waste collected from the city without any distinction are treated and collected according to the type of alloy. I could not.

Patent Document 2 discloses a recycling method and a recycling method in which an aluminum wrought material and an aluminum cast material of a used automobile are separated and collected to regenerate the collected aluminum wrought material as an automobile aluminum wrought material again. A plant is disclosed.
In the disclosed method, since the part where the wrought material is used in the used car is clearly known, when disassembling in the first separation step, the aluminum casting part or the aluminum alloy is mixed when mixed. Impurities such as iron and silicon are removed, and the remaining part is separated as a processing target.

  In the second separation step, the portion separated in the first separation step is crushed, and the crushed pieces mainly composed of aluminum are separated by a known technique such as magnetic separation. Since only the portion where the usage rate of the aluminum wrought material is already large in the first separation step, high-quality aluminum material can be regenerated from the crushed pieces separated in the second separation step. Therefore, in the subsequent material production process, the crushed pieces separated in the second separation process can be dissolved to produce an automotive aluminum wrought material.

  The recovery system of the aluminum wrought material disclosed in Patent Document 2 is a method in which an operator who is familiar with members used in automobiles manually separates the wrought material and is generally accumulated in a stock yard. It cannot be used for the purpose of automatically selecting the aluminum wrought material from the state in which the aluminum wrought material and the aluminum casting are mixed as in the case of waste.

Further, Patent Document 3 discloses an automatic identification device capable of automatically identifying a crushed metal piece and a cast material from an aluminum alloy crushed metal piece and selecting based on the result. ing.
The disclosed method uses a discriminant analysis method, which is a kind of multivariate analysis method, to identify the one derived from the wrought material and the one derived from the cast material based on the form of the crushed pieces, the weight, The volume, area, vertical dimension, horizontal dimension, maximum height, center of gravity height, etc. are measured, variables used for discriminant analysis are calculated, and these variables are determined in light of a large amount of case data registered in advance. The case data is a result of accumulating the measurement results of the wrought and cast materials actually obtained in the past.

  Although the disclosed method has great results when applied to a process in which wastes of the same form are repeatedly generated, such as aluminum shards discarded at a shredder processing facility of an end-of-life vehicle, Because it is not a method based on typical characteristics, a sufficient discrimination rate should be achieved when the form of the aluminum alloy wrought material contained in waste, such as general waste or industrial waste that does not specify the source, cannot be specified. Is considered difficult.

Japanese Patent Laid-Open No. 7-256231 JP 2003-277837 A JP 2009-262009 A

Conventionally, methods for separating and recovering aluminum and aluminum alloys from other metals have been put to practical use, but no highly accurate and efficient means for selecting and recovering by aluminum alloy type has been known.
For example, the separation method disclosed in Patent Document 2 relies on a first separation step by a skilled worker and is difficult to automate. In addition, the determination method disclosed in Patent Document 3 needs to execute complicated image processing and an advanced determination algorithm for handling an outline image taken from each direction, and collates with the shape data of the fragmented pieces collected as a sample. Therefore, accurate determination cannot be performed for a fragment having a shape different from that of the sample.
As described above, since an appropriate method for determining by classifying the aluminum alloy cannot be obtained, it has not been possible to provide a facility for sorting and collecting the aluminum alloy by type.

  Accordingly, the problem to be solved by the present invention is to provide an aluminum alloy discriminating method for selecting a high-grade aluminum alloy type from other aluminum alloy types with a small amount of heavy metal additives that can be used as a wrought material. It is to provide an aluminum alloy sorting facility that sorts and collects aluminum alloy types that can be used as stretched materials.

In order to solve the above problems, the aluminum alloy discrimination method according to the present invention is:
(1) preparing a plurality of calibration samples made of a first aluminum alloy to be collected and having different thicknesses and a comparison sample made of a second aluminum alloy to be excluded;
(2) irradiating two X-rays having different energies to the calibration sample and the comparison sample to measure the intensity of the transmitted X-rays for each unit area;
(3) a step of arranging measurement results for each unit area on a measurement plane defined by two-dimensional coordinates each having transmission amounts relating to two X-rays having different energies as axes;
(4) A discriminant band is defined in the measurement plane so that an area having a large distribution concentration of points indicating the measurement results regarding the calibration sample is sandwiched between the upper curve and the lower curve, and the measurement plane is in the discriminant band. Dividing into a density region, a high density region outside the upper curve, and a low density region outside the lower curve;
(5) First, the calibration sample and the comparison sample are selected based on the ratio of the measurement result regarding the calibration sample included in the high density region or the low density region, in contrast to the distribution of the measurement result regarding the comparison sample. Determining a second threshold value for determining a calibration sample from a ratio of measurement results regarding the calibration sample included in the medium density region;
(6) irradiating the sample to be selected with two X-rays and measuring the intensity of transmitted X-rays per unit area;
(7) classifying the two X-ray intensity measurements per unit area into a high density region, a medium density region, and a low density region;
(8) When the ratio included in the high-density region or the low-density region is smaller than the predetermined first threshold value and the ratio included in the medium-density region is larger than the predetermined second threshold value, the sample to be sorted is a product to be collected. Determining that there is,
It is characterized by including.

  The X-ray intensities transmitted by irradiating two X-rays having different energies are measured for each unit area over the entire surface of each of a plurality of samples having different thicknesses, and the two types of X-ray transmission intensities are plotted on the horizontal and vertical axes Plot on a measurement plane consisting of coordinate planes. X-rays having different energies can be realized by using the same X-ray and transmitting the shielding plate and not transmitting the shielding plate. Taking the intensity of X-rays weakened through the shielding plate on the vertical axis and the intensity of strong X-rays not passing through the shielding plate on the horizontal axis, from the upper right of the coordinate plane toward the origin as the sample thickness increases. A graph distributed on an arcuate curve is obtained. In this graph, depending on the sample, an element having a lower X-ray transmittance is drawn on the upper left side on the coordinate plane, and an element having a higher X-ray transmittance is drawn on the lower right side.

Therefore, by using this measurement method, when drawing a discrimination graph for a standard material, it is possible to use the fact that measurement points of materials with different elemental structures appear at positions outside the discrimination graph. Even if fluctuates, the metal can be correctly identified based on the content ratio of the element.
Here, the unit area is the minimum area that one measurement value outputs when dividing and measuring the area of the sample, and is an area that is an integral multiple of the range detected by one element of the X-ray sensor.

The belt conveyor, one X-ray source provided on the belt conveyor, and two X-ray detection linear sensors corresponding to the X-ray source below the belt conveyor are orthogonal to the moving direction of the belt conveyor. Provides a method for measuring the transmission intensity of two X-rays with different intensities for each unit area over the entire surface of the sample by using an X-ray detector provided in parallel in the direction to be measured can do.
By placing a shielding plate on one surface of the two X-ray detection linear sensors and attenuating the X-ray intensity, different X-ray intensities can be measured between the two sensors. The shielding plate has a function of appropriately attenuating the X-ray intensity when X-rays are transmitted, and various materials such as a metal plate can be used, and a thin copper plate may be used. By adding the X-ray transmission characteristics of the shielding plate to one X-ray irradiation optical path, substantially the same effect as when an energy difference is given between two X-rays transmitted through the object to be measured can be brought about.

In this measurement method, the X-ray irradiates the sample conveyed by the belt conveyor and the X-ray transmitted through the sample is measured by two X-ray detection linear sensors, and the unit measurement area corresponding to the same position in the sample is used. Two measured values of X-ray transmission intensity can be made to correspond. In order to make the two measurement positions correspond to each other, the distance difference may be corrected by using the time during which the belt conveyor travels the distance between the two X-ray detection linear sensors.
A determination curve in the measurement plane that can be effectively used for determining different metals can be obtained by calibrating using a calibration sample. Further, the threshold value used for the determination is determined based on the measurement result obtained for the comparison sample formed of the distribution of the measurement value related to the calibration sample and the material to be excluded.

A plurality of calibration samples having different thicknesses formed from materials to be collected are prepared. For such a sample, the X-ray intensity transmitted by irradiating two X-rays with different energies is measured, and the measurement result is plotted on a two-dimensional coordinate having two transmission amounts of two X-rays as two axes. It is distributed along the arcuate curve according to the change of the height.
However, due to fluctuations in irradiated X-rays and fluctuations in the X-ray transmission path, the measured values of X-ray intensity show some variation even at measurement points having the same thickness. Therefore, a plot group having a certain width is formed on the graph. Therefore, in order to include many measurement points, it is necessary to determine the determination region so as to form a band having a width.

  In a simple case in which different metals are discriminated from each other, it is possible to determine that the metal material to be selected is included when the measurement points on the entire surface of the sample to be discriminated are included in the 100% determination band. However, when the target is an alloy whose measurement points are close to each other, the metal to be excluded tends to be mixed if the width of the judgment band is made too large. It is more reliable to determine the difference between the two materials stochastically. That is, assuming that the determination area sandwiched between the upper curve and the lower curve is called a medium density area, even if there are measurement points that are outside the medium density area, when many measurement points are included in the medium density area, It can be determined probabilistically that the material is the material of the calibration sample.

Conventionally, this X-ray transmission type discrimination method has been used for sorting between different kinds of mixed metals such as aluminum and copper. However, it is difficult to apply to different systems of aluminum alloys because the density difference is small. there were.
According to the aluminum alloy discrimination method of the present invention, the X-ray absorption rate differs slightly depending on the type of aluminum alloy, that is, any aluminum alloy whose X-ray transmission intensity is reduced contains a larger amount of metals heavier than aluminum such as copper and zinc. In addition, paying attention to the fact that the measurement results for each unit area in the above X-ray transmission type discrimination method are distributed with variation, the measurement results are subjected to statistical processing to detect slight differences. Thus, the aluminum alloy derived from the cast material and the aluminum alloy derived from the wrought material can be discriminated according to the alloy system.

However, the difference in transmitted X-ray intensity between aluminum alloys is not large enough and the thickness of the waste varies over a large range. It is difficult to detect and sort.
The aluminum alloy discriminating method of the present invention uses a discriminating region and a threshold value obtained by using a calibration sample to detect a statistical difference in the distribution of measured values and determine the type of aluminum alloy. is there.

  In the aluminum alloy discriminating method of the present invention, it is verified that the ratio of the measurement results classified into the medium density region is larger than the second threshold value (for example, 46%) obtained statistically, and the aluminum alloy (first (1 aluminum alloy) is determined, and further, it is excluded by verifying that the ratio of the measurement results classified into the high density region is smaller than the statistically determined first threshold (for example, 24%). Differentiating from another type of aluminum alloy containing a large amount of heavy metals (second aluminum alloy), the passed material is judged as the aluminum alloy to be selected.

  Since the difference in X-ray transmittance is small between aluminum alloys, it is necessary to use a more precise method. Therefore, a comparison sample made of the second aluminum alloy to be excluded is prepared, the same measurement as the calibration sample is performed on the comparison sample, and the comparison is made with the measurement result and the measurement result regarding the calibration sample. The sorting performance between the first aluminum alloy and the second aluminum alloy is improved by adjusting the position of the band and the first threshold value and the second threshold value.

To be precise, the aluminum alloy (first aluminum alloy) that can be currently selected by the method of the present invention does not contain much heavy metal components in aluminum, for example, alloy number 1000 series aluminum, alloy number 3000 series, and 5000 series. And 6000 series heavy metal-free aluminum alloys, mainly to the wrought material-derived waste.
Since these aluminum alloys classified by system contain only a few heavy metals, they can be recycled as appropriate aluminum alloys by fusing and adjusting the composition after recovery.

The aluminum alloy (second aluminum alloy) to be excluded is an alloy number 2000 series containing several percent of copper and a 7000 series alloy containing several percent of zinc.
In the second aluminum alloy, copper or zinc absorbs more X-rays than aluminum, so if the thickness is the same, the measurement result relating to the transmitted X-ray intensity is positioned on the upper left side in the two-dimensional coordinate plane.
In addition, what was made into the 2nd aluminum alloy here can be selected with sufficient precision by exclusion, if a viewpoint is changed.

The determination curve in the measurement plane used for determining aluminum alloys can be obtained by calibrating using a calibration sample. Further, the threshold value used for the determination is determined based on the measurement result obtained for the comparison sample formed of the distribution of the measurement value related to the calibration sample and the material to be excluded (second aluminum alloy).
When the results of measuring the transmitted X-ray intensities of two X-rays having different energies for a plurality of calibration samples having different thicknesses are plotted on the measurement plane, they are distributed in a strip shape having a width along an arcuate curve. Therefore, the determination curve needs to be an arcuate determination band having a band width.

Since the second aluminum alloy to be excluded is a high-density metal having a lower X-ray transmittance than the first aluminum alloy, the plot position of the measured value is on the higher-density side than the first aluminum alloy in the two-dimensional coordinate plane. It is biased to a certain upper left side.
Therefore, the first threshold value is a value that does not exceed the first threshold value even when the measurement result related to the first aluminum alloy is included in the high-density region due to statistical fluctuations. It is preferable that the value does not fall below the first threshold even if the measurement results included in the high-density region decrease due to statistical fluctuation.
The second threshold value is preferably selected such that the measurement result regarding the first aluminum alloy does not fall below the second threshold value even if the ratio included in the medium density region decreases due to statistical fluctuations.

If the discrimination band and threshold value are determined in comparison with the second aluminum alloy, even if the distribution in the measurement result between the first aluminum alloy and the second aluminum alloy is close, the small difference between them is detected. And can be collected with sufficient accuracy.
In order to further increase the determination accuracy of the first aluminum alloy, it is desirable to repeat the trial and error a sufficient number of times.
As described above, the aluminum alloy discriminating method of the present invention detects the statistical difference in the distribution of measured values by using the discriminating region and the threshold value obtained by using the calibration sample, so Can be determined.

In order to solve the above problems, the aluminum alloy sorting equipment according to the present invention includes an X-ray transmissive metal sorter for sorting aluminum alloys and an X-ray transmissive metal sorter by sorting aluminum alloys from other wastes. Pre-treatment equipment for supplying aluminum alloy to the machine is provided.
The X-ray transmission type metal sorter is a belt conveyor that conveys a sample to be sorted of aluminum and aluminum alloy, an X-ray source provided above the belt conveyor, and an X-ray transmitted through the belt conveyor. Two X-ray sensors for measuring the intensity, one of the two X-ray sensors passing through a metal plate placed on the sensor and reducing the X-ray intensity for detection; Using the output of the X-ray sensor, based on the transport distance of the belt conveyor, the intensity of transmitted X-rays per unit area at the same position of the sample is calculated, and the two X-ray intensities per unit area are calculated as the first aluminum alloy. Are classified into a high-density region, a medium-density region, and a low-density region that can be selected from the second aluminum alloy that has been calibrated in advance using a calibration sample, and a ratio included in the high-density region is predetermined. Less than the first threshold of When the ratio included in the temperature region is greater than a predetermined second threshold value, it is determined as the first aluminum alloy, and when the measured sample reaches the end position of the belt conveyor, the first aluminum alloy is determined as the first aluminum alloy according to the determination result. X-ray transmission type metal sorter having a determination device for generating a command for distributing another aluminum alloy to the second storage tank in the storage tank, and a distribution device for distributing the sample to the collection side and the exclusion side according to the command of the determination device Is provided.

  The pretreatment equipment in the aluminum alloy sorting equipment according to the present invention includes a sieve device that sorts and supplies waste of a predetermined size or more, a metal sorter that eliminates non-metallic items from waste of a predetermined size or more, and metal sorting It is desirable to include an aluminum sorter that sorts and supplies aluminum and aluminum alloys from the metal waste supplied from the machine.

  Also, an X-ray transmission type metal sorter is suitable as the aluminum sorter, and the transmission X-rays per unit area at the same position of the sample based on the transport distance of the belt conveyor using the output of two X-ray sensors. The aluminum region which calculated the intensity of the aluminum and made it possible to sort the aluminum and aluminum alloy from other metals obtained by calibrating two X-ray intensities per unit area in advance using a calibration sample for aluminum and aluminum alloy It is preferable that the metal is determined to be a metal other than aluminum and aluminum alloy when it deviates from the range.

  The aluminum alloy discriminating method of the present invention and the aluminum alloy sorting equipment using the same supply aluminum scrap obtained by sorting aluminum and aluminum alloy from waste, and derived from wrought aluminum alloy and cast material By sorting and recovering aluminum alloys according to alloy system, energy and work processes in aluminum recovery can be significantly reduced.

It is a perspective view explaining notionally the composition of the metal sorter which performs the aluminum alloy discriminating method concerning one embodiment of the present invention. It is drawing explaining the principle which measures an X-ray transmissive state in the aluminum alloy discrimination method of this embodiment. It is drawing explaining the method of calculating | requiring the measurement result in the aluminum alloy discrimination method of this embodiment. It is drawing which shows the example which plotted the measured value of the sample for a calibration in the aluminum alloy discrimination method which concerns on this embodiment. It is drawing which shows the principle which sorts copper and aluminum with the aluminum alloy discrimination method. It is a chemical composition table | surface of an aluminum alloy. It is the graph which plotted the measurement result tried about the aluminum alloy of exclusion object. It is drawing explaining the principle which determines the area | region and threshold value which are used for determination in the aluminum alloy discrimination method based on this embodiment. It is drawing which shows the state which classified the measured value of the sample for calibration in the aluminum alloy discriminating method concerning this embodiment. It is a flowchart explaining the procedure of the aluminum alloy discrimination method which concerns on this embodiment. It is a table | surface which shows the example of a determination result of the aluminum alloy in the aluminum alloy discrimination method which concerns on this embodiment. It is a flowchart showing the process sequence of the aluminum alloy sorting equipment which concerns on one Embodiment of this invention.

  Hereinafter, an aluminum alloy discrimination method and an aluminum alloy sorting facility according to the present invention will be described in detail with reference to the drawings based on examples.

FIG. 1 is a perspective view conceptually illustrating the configuration of an X-ray transmissive metal sorter used in one embodiment of the present invention.
The aluminum alloy discriminating method according to the present embodiment can be implemented by using an X-ray transmission type metal sorter as shown in FIG. The X-ray transmission type metal sorter according to the present embodiment is provided with a belt conveyor 1 that conveys a sample 21, an X-ray source 3 provided above the belt conveyor 1, and a belt conveyor 1 that is provided below the belt conveyor 1 and transmits the sample 21. The X-ray sensor 5 includes a pair of X-ray sensors 5 that measure the intensity of the X-rays, and a determination circuit 7 that determines the sample by calculating using the measurement signal.

  The double X-ray sensor 5 includes a first X-ray detection linear sensor 9 and a second X-ray detection linear sensor 11 arranged in parallel. The first X-ray detection linear sensor 9 has a metal plate (shielding plate) on the X-ray incident surface. ) The X-ray transmitted through the sample 21 with 13 is weakened and the intensity is measured. The two X-ray detection linear sensors 9 and 11 are sensors of the same type, and have a structure in which X-ray detection elements are arranged on a line, and the measurement result of each element is scanned and sequentially output. Each element has a measurement position determined for each element, and outputs a measurement signal corresponding to the intensity of the X-ray transmitted through the unit area portion of the sample 21.

Since the sample 21 is moved by the belt conveyor 1, the X-ray detection linear sensors 9 and 11 measure the transmitted X-ray intensity over the entire area of the sample 21.
In order to make the measurement positions of the first X-ray detection linear sensor 9 and the second X-ray detection linear sensor 11 easily correspond to each other, the X-ray detection linear sensors 9 and 11 are arranged so as to be orthogonal to the transfer direction of the belt conveyor 1. It is preferable to do.

  The X-rays 15 emitted from the X-ray source 3 irradiate a wide area on the belt conveyor 1 where the sample 21 is mounted, but the X-rays detected by the X-ray detection linear sensors 9 and 11 are arranged on the line. However, since it is limited to the X-rays incident on the detection element array, the irradiated X-rays can be regarded as the slit lights 17 and 19. Further, since the X-rays incident on the first X-ray detection linear sensor 9 are transformed by the X-ray absorption characteristics of the metal plate 13, the X-ray slit lights 17 and 19 are formed by X-rays having substantially different characteristics. It can be regarded as a thing.

2 and 3 are diagrams for explaining a method of detecting an X-ray transmission state at a certain point on the sample 21 in the X-ray transmission type metal sorter used in the present embodiment.
The X-ray transmission type metal sorter determines the type of metal using the fact that the X-ray transmittance decreases as the metal element number increases.
Since the amount of X-ray transmission is affected by the thickness of the sample, the influence of the thickness is corrected using two transmission X-ray intensity measurement results obtained by irradiating X-rays having different characteristics. In X-ray measurement, fluctuations in X-ray radiation and fluctuations in X-ray measurement cannot be ignored, so a large number of measurements are performed on one sample, and the results are processed statistically to ensure reliability. Yes.

  As shown in FIGS. 2 and 3, the second X-ray detection linear sensor 11 measured the X-ray transmission state at a position 23 of the sample 21 moving by the belt conveyor 1 by the first X-ray detection linear sensor 9. The measurement is performed after a predetermined time Δ has elapsed from the time point. The time Δ is a time obtained by dividing the interval D between the sensor rows by the speed v of the belt conveyor 1. Therefore, two X-ray transmission intensity measurement values measured for two X-rays having different intensities at the same measurement positions 23 and 25 of the sample 21 can be easily matched.

In this way, the measurement values of the X-ray transmission intensity for each unit area obtained by irradiating two different X-rays on the plurality of samples 21 having different thicknesses are plotted on a predetermined measurement plane over the entire area of each sample. To do.
The measurement plane is a two-dimensional coordinate plane with the measurement output of the first X-ray detection linear sensor 9 as the vertical axis and the measurement output of the second X-ray detection linear sensor 11 as the horizontal axis. The vertical axis of the measurement plane corresponds to the case where the X-ray detection sensor is covered with the metal plate 13 and substantially weak X-rays are irradiated. The scale of the measurement plane is aligned with the output range of each sensor on both the horizontal axis and the vertical axis. Therefore, the scale is not directly consistent with physical units.

FIG. 4 shows five calibration samples having thicknesses of 1 mm, 3 mm, 7 mm, 12 mm, and 25 mm for aluminum alloy 6063, which is frequently used as a sash material, and these samples were irradiated with X-rays to obtain the first X The results measured with the line detection linear sensor and the second X-ray detection linear sensor are plotted on the measurement plane for the entire sample surface.
In the graph of FIG. 4 and the like, with respect to the measurement value by the first X-ray detection linear sensor and the measurement value by the second X-ray detection linear sensor, the state where no X-rays are transmitted is zero and the sample is not placed on the belt. The measured value is normalized so that it comes to the full scale position.
Since the measurement results vary due to fluctuations in the irradiated X-rays and fluctuations in the X-ray transmission path, the plots of the measurement results are distributed in blocks, but the origin and upper right end points from the thicker to the thinner of the sample. It can be seen that it is distributed along an arcuate curve connecting the two.

Accordingly, it can be seen that the measured value of the sample made of the aluminum alloy having the alloy number 6063 is expressed along the arcuate curve shown in FIG. 4 with the thickness.
In consideration of the variation of the measured value, by setting a determination region sandwiched between the upper curve and the lower curve in the arcuate curve, most of the measured value of the aluminum alloy of alloy number 6063 is included in the determination region. can do.
In addition, the measurement results of the material with a larger atomic weight and smaller X-ray transmittance than the sample aluminum alloy are plotted on the upper left side of this bow curve, and for the material with a smaller atomic weight and larger X-ray transmittance, plotted on the lower right side of the bow curve. Is done.

Therefore, for example, if the metal has a different X-ray transmittance from that of an aluminum alloy such as copper, the two metals can be easily distinguished by the above method.
FIG. 5 is a diagram in which the results of measurements made on samples made of various aluminum alloys and the results of measurements made on copper samples in the same procedure are plotted together on the same measurement plane.
As shown in the figure, it is necessary to slightly increase the width of the judgment area in order to include all aluminum alloys, but the copper measurement results are larger than the aluminum alloy measurement results on the upper left side of the measurement plane. Therefore, the ratio included in the determination region for the aluminum alloy is small.

  In this way, it is possible to easily distinguish between an aluminum alloy and copper on the condition that the measurement result is included in the determination region to some extent. Therefore, conventionally, this X-ray transmission type discrimination method has been used for sorting between different kinds of mixed metals, but it is difficult to apply to different systems of aluminum alloys because the difference in X-ray transmittance is small. Met.

  However, as a result of the inventors' research, aluminum alloys can also be distinguished between types corresponding to applications by utilizing the presence of added heavy metals and using the precise judgment procedure developed recently. found.

FIG. 6 is a chemical composition table of the aluminum alloy. The table shows the chemical components determined for each type of alloy with respect to alloys representing aluminum and aluminum alloys.
According to the table of FIG. 6, alloy number 3003 used for heat exchanger materials, alloy number 6063 used for building sashes, alloy number 5083 used for welded structure materials, etc. as well as aluminum of alloy number 1050 It can be seen that the aluminum alloy does not contain a large amount of heavy metal having an atomic weight larger than that of aluminum.

  Since these aluminum and aluminum alloys do not contain much metal other than aluminum, even if they are mixed together after recovery, various kinds of aluminum alloys are produced by mixing the appropriate metals as the alloy base material and adjusting the components. can do. In particular, since alloy number 6063 is discarded in large quantities as a sash, by collecting it together, it can be reused as a sash extension material by a simple process.

  On the other hand, in the table of FIG. 6, the alloy number 2024 known by the name of duralumin contains 3.8 to 4.9% copper, and the alloy number 7N01 that is a welded structure material contains 4.0 to 5 zinc. 0.0% is included.

    Therefore, if a group of aluminum and aluminum alloy that does not contain much heavy metal is called a first aluminum alloy as a collection target, and a group of aluminum alloys containing heavy metal is called a second aluminum alloy as a target of exclusion, the first aluminum alloy is distinguished. The aluminum alloy and the second aluminum alloy have different heavy metal contents, so the X-ray transmittance is different. When the previous aluminum alloy discrimination method is applied, the measurement result plot is expected to be slightly biased on the measurement plane. The

FIG. 7 shows a result of plotting the result of measurement according to the procedure described above on the same measurement plane for alloy number 2024 as a representative of the second aluminum alloy. In the drawing, a determination region suitable for the alloy number 6063 shown in FIG. 4 is entered.
According to FIG. 7, it can be seen that the plot group of the measurement result of alloy number 2024 is slightly shifted to the upper left side, that is, the high density side from that of alloy number 6063.
However, in particular, a sample with a thin alloy number 2024 or the like has a central portion of a plot of measurement results almost included in the determination region of alloy number 6063, and it seems that it is difficult to determine the difference between the two.

Thus, as a result of intensive studies, the inventors have made it possible to make the determination by limiting the target aluminum alloy and appropriately adjusting the determination region and the determination level.
FIG. 8 is a diagram conceptually illustrating the principle of determining a determination region and a threshold value for determination in the aluminum alloy determination method of the present embodiment.

When one sample is measured by this discrimination method, the measurement result over the entire surface of the sample fluctuates due to fluctuations in X-ray irradiation or X-ray measurement, and therefore shows a distribution with a high probability at the center and a low probability at the periphery. In FIG. 8, this distribution is represented by a normal distribution as a representative. When another sample having the same material is measured, the measurement results vary and show a distribution in which the median is shifted from the previous distribution, as indicated by a plurality of solid lines in the figure. Since the first aluminum alloy includes a plurality of aluminum alloys having different compositions, the fluctuation of the distribution is further increased.
On the other hand, since the second aluminum alloy contains heavy metal, the X-ray transmittance is smaller than that of the first aluminum alloy, and as shown by the wavy line in the figure, the distribution of measurement results is biased toward the high density side.

Therefore, along the arcuate curve in which the measurement results are distributed, a judgment area sandwiched between the upper curve and the lower curve is defined, and the measurement result plot is included in the high density area on the higher density side than the upper curve. The ratio and the medium density ratio included in the medium density area that is the determination area are obtained, and the type of the alloy is determined based on these ratios.
That is, even if the measurement of the first aluminum alloy fluctuates toward the high density side, a high density ratio that can be distinguished from the second aluminum alloy is found and set as the first threshold value. Furthermore, even if the measurement result of the first aluminum alloy fluctuates on the low density side, a medium density ratio that can be determined not to be a metal or plastic lighter than aluminum is found and set as the second threshold value.

When the first aluminum alloy is selected from the waste pieces, the ratio included in the high-density region is calculated from the results of measurement on the entire surface of the waste pieces.
When the ratio of the measurement results included in the high density region is smaller than the first threshold value, the waste piece is likely to be the first aluminum alloy instead of the second aluminum alloy. Furthermore, if the ratio of the measurement results included in the medium density region is larger than the second threshold value, the possibility of a substance having a lower density than that of the first aluminum alloy can be excluded.

In the aluminum alloy discriminating method of the present embodiment, the determination is made using two criteria for the measurement result, so that the first aluminum alloy can be discriminated with high accuracy.
Note that the upper curve and the lower curve that define the determination region, the first threshold value, and the second threshold value are important indexes that determine the determination result, but the threshold value changes depending on how the curve is defined. The optimum value varies depending on the discrimination target group and the discrimination device. Therefore, it is necessary to obtain these indicators by trial and error for the configuration actually used.

FIG. 9 shows a result of measuring five calibration samples having different thicknesses from 1 mm to 25 mm, which were created with an alloy number 6063 using the aluminum alloy discrimination method according to the present embodiment, and a high density region over the entire surface of the sample. (Black dots), medium density areas (intermediate color points), and low density areas (gray dots) are classified and displayed. The medium density area which is the determination area is determined by trial and error.
In the sample having a thickness of 1 mm, the number of measurement points included in the low density region indicated in gray and the high density region indicated in black is relatively large. However, as the thickness increases, the area included in the medium density region indicated by the intermediate color increases. There is a slight difference in the proportion of each density region depending on the thickness.

Since all the samples to be measured are made of the first aluminum alloy to be selected, it is necessary to make a determination under conditions including all these data. For this purpose, the position of the determination region is appropriately determined. However, since it is difficult to perform accurate determination by itself, an index relating to the distribution of the measurement result is taken in.
In the present embodiment, the ratio of the first aluminum alloy measurement result included in the determination region is 46% or more in all cases. However, when looking at the measurement results of Alloy No. 2024 and Alloy No. 7N01, which are the second aluminum alloys to be excluded, in most cases, it is 46% or less, but there are cases where it exceeds 46%.

On the other hand, in the second aluminum alloy, the ratio of the measurement results included in the high density region was large, and it was confirmed that even if the distribution of the measurement results fluctuated, the value did not decrease to 24%.
Accordingly, the second threshold value that determines the lower limit for the ratio included in the medium density region is set to 46%, and the first threshold value that sets the upper limit for the ratio of the measurement points included in the high density region is set to 24%. It has been found that the first aluminum alloy and the second aluminum alloy can be distinguished by satisfying two criteria.

FIG. 10 is a flowchart for explaining the procedure of the aluminum alloy discriminating method of the present embodiment using the above method.
In the aluminum alloy discriminating method of the present embodiment, a determination criterion is determined before determining waste. The determination criterion is determined by the determination region, the first threshold value, and the second threshold value. Thereafter, the determination target sample is measured and determined according to the determination criterion.

  In order to determine the criterion, first, a first aluminum alloy calibration sample and a second aluminum alloy comparison sample having different thicknesses are prepared (S11). The prepared calibration sample and comparison sample are sequentially applied to an X-ray transmission type metal sorter and irradiated with two X-rays having different energies to measure the transmission X-ray intensity for each unit area (S12). The measurement results for each unit area are arranged on the measurement plane (S13). The measurement plane is a two-dimensional coordinate plane having two transmitted X-ray intensities as two axes. In addition, what is necessary is just to perform in the computer the process of arrange | positioning a measurement result on a measurement plane.

  In the measurement plane on which the measurement results are plotted, a discrimination zone can be defined by connecting regions having a large distribution density of the measurement results for the calibration sample (S14). Next, draw the upper and lower curves across the discriminant band, and measure the measurement plane with the middle density region sandwiched between the upper and lower curves, the high density region outside the upper curve, and the outside of the lower curve. Divide into low density regions (S15).

A first threshold value for selecting the calibration sample and the comparison sample is determined based on the ratio of the measurement result of the calibration sample included in the high-density area, as compared with the distribution of the comparison sample measurement result (S16). Next, a second threshold value for determining the first aluminum alloy is determined from the ratio of the measurement results of the calibration sample included in the medium density region (S17).
In this way, a criterion for sorting the sample to be sorted by the X-ray transmission type metal sorter is defined.

After determination criteria corresponding to the measurement conditions are determined, determination is performed by measuring the target sample.
The sample to be sorted is mounted on a belt conveyor of an X-ray transmission type metal sorter, and irradiated with two substantially different X-ray slit lights while moving, and the transmitted X-ray intensity for each unit area is measured and output. (S21). Two X-ray intensity measurement values for each unit area are classified into a high density region, a medium density region, and a low density region (S22). When the ratio of the measurement results included in the high density region is smaller than the first threshold value determined earlier and the ratio included in the medium density region is greater than the second threshold value determined previously (S23), the sample to be sorted is to be collected. It is determined that the product is a product (S24). If any of these conditions is not satisfied, the sample to be sorted is determined to be excluded (S25).
After the determination of the sample to be selected, if the sample to be selected remains, the process returns to the beginning of the determination step and the determination is repeated. When all the samples to be selected have been determined, the operation is finished (S26).

FIG. 11 is a table showing the ratio of measurement results included in each region when the aluminum alloy discrimination method of the present embodiment is applied to various samples. Each sample varies in thickness from 1 mm to 25 mm or 30 mm. The numerical values shown in the table indicate the ratio when the measurement results are distributed to the high density region (H), the medium density region (M), and the low density region (L).
In the bottom column, for each alloy type, “◯” is entered when all samples are judged to be the first aluminum alloy, and “X” is entered when judged to be the second aluminum alloy.
Alloy numbers 1000, 3003, 5083, and 6063 included in the first aluminum alloy satisfy all the conditions and are determined to be the first aluminum alloy, and alloy numbers 2024 and 7N01 included in the second aluminum alloy all satisfy the conditions and the second It is determined to be an aluminum alloy. As described above, according to the determination method of the present embodiment, all the samples to be tried can be correctly sorted into the first aluminum alloy and the second aluminum alloy.

FIG. 12 is a flowchart for explaining the flow of the processing procedure in the aluminum alloy sorting equipment according to one embodiment of the present invention.
Conventionally, there has been an aluminum alloy sorting facility that sorts aluminum and aluminum alloys and other metals quickly and in large quantities, but no technology has been found to sort aluminum alloys quickly and in large quantities by alloy system.
The aluminum alloy sorting equipment of the present embodiment incorporates an X-ray transmission type metal sorter using the above-described aluminum alloy determination method, and is obtained by sorting from mixed metal obtained from waste collected from the city. The aluminum alloy crushed pieces are further sorted, so-called aluminum alloy wrought material is sorted and collected.

  The X-ray transmission type metal sorter used in the aluminum alloy sorting facility of the present embodiment includes a belt conveyor for conveying a sample to be sorted of aluminum and aluminum alloy, an X-ray source device provided above the belt conveyor, a belt A series of two X-ray detection linear sensors arranged in parallel to measure the intensity of transmitted X-rays provided under the conveyor, and one X-ray detection linear sensor is placed over the sensor. Unit at the same position of the sample based on the transport distance of the belt conveyor using the X-ray sensor that transmits through the metal plate and detects the X-ray intensity weakened and the output of the double X-ray sensor The intensity of transmitted X-rays for each area is calculated, and it is possible to select two X-ray intensities for each unit area from the second aluminum alloy obtained by calibrating in advance using a calibration sample for the first aluminum alloy. High density When the ratio included in the high density area is smaller than the predetermined first threshold and the ratio included in the medium density area is larger than the predetermined second threshold, When the measured sample reaches the end position of the belt conveyor, a command to distribute the first aluminum alloy to the first storage tank and the other aluminum alloy to the second storage tank is generated according to the determination result. And a distribution device that distributes the sample to the selection target side and the non-target side by driving an air nozzle in accordance with an instruction from the determination device.

The aluminum alloy sorting equipment of this embodiment is equipped with an eddy current metal sorter and two X-ray transmission type metal sorters, and performs a three-stage sort on a 10 mm square or more crushed piece sorted by a sieve. And recover the aluminum alloy wrought material.
Referring to FIG. 12, a mix sample obtained from commercial scrap containing iron, copper, rubber, plastics, etc. in addition to aluminum, is crushed into pieces with a size of 10 mm square or more by sieving. Sort out. Fine crushed pieces of 10 mm square or less are difficult to separate with a sorter and are removed.

The mixed sample that has been prepared into pieces of 10 mm square or more is subjected to an eddy current metal sorter as the first stage of sorting to remove non-metals such as rubber, wood scrap and resin, and mixed metal consisting of only various metals. Sort out.
The selected mixed metal is subjected to an X-ray transmission type metal sorter that is set for aluminum sorting as the second stage of sorting to remove aluminum other than metals and large foreign matters, Separates aluminum scrap composed of aluminum and aluminum alloy fragments.

Aluminum scrap that contains only aluminum is used as an X-ray transmission type metal sorter that is conditionally set so that it can be sorted by alloy system according to the aluminum alloy discrimination method of the present invention described above as the third stage of sorting. By applying, the aluminum alloy of alloy number 6063 is separated and recovered.
The aluminum alloy sorting equipment of this embodiment can recover the aluminum alloy of alloy number 6063 with high quality that can be sufficiently used as the main raw material of the wrought material. The regenerated aluminum alloy having the alloy number 6063 can be reused as a wrought material, for example, as a window frame sash.

In addition, 1000 series, 3000 series, 5000 series, and 6000 series aluminum alloys may be mixed in the aluminum alloy obtained by the final third stage selection, but these components are all components other than aluminum. Since the metal content is small and contributes to the yield improvement in the regeneration process of Alloy No. 6063, there is no particular problem even if they are mixed.
The aluminum alloy finally removed is 2000 series or 7000 series aluminum alloy or aluminum die cast. These aluminum alloys can be recycled as casting materials.
It should be noted that the aluminum alloy determination method of the present invention and the aluminum alloy sorting equipment using the same are not limited to the reproduction of alloy number 6063, but may be determined for 1000 series, 3000 series, 5000 series aluminum alloys. it can. From the opposite viewpoint, it is also possible to accurately discriminate 2000 series and 7000 series aluminum alloys.

  The aluminum alloy determination method according to the present invention and the aluminum alloy sorting equipment using the same can selectively recover the wrought material from the aluminum alloy waste, so that the recovered aluminum can be recycled as the wrought material. It is possible to increase the number of reuse destinations and to significantly reduce the melting energy and the work process in the regeneration process of the wrought material.

DESCRIPTION OF SYMBOLS 1 Belt conveyor 3 X-ray source 5 X-ray sensor 7 Determination circuit 9 1st X-ray detection linear sensor 11 2nd X-ray detection linear sensor 13 Metal plate 15 X-rays 17 and 19 X-ray slit light 21 Samples 23 and 25 Measurement position

Claims (5)

Preparing a plurality of calibration samples made of a first aluminum alloy to be collected and having different thicknesses and a comparison sample made of a second aluminum alloy to be removed;
Irradiating two X-rays having different energies to each of the calibration sample and the comparison sample to measure the intensity of transmitted X-rays per unit area;
Arranging a measurement result for each unit area on a measurement plane defined by two-dimensional coordinates having two transmission axes of the two X-rays;
A discriminant band is defined on the measurement plane so that a region having a large distribution density of points indicating the measurement results relating to the calibration sample is sandwiched between the upper curve and the lower curve, and the measurement plane is defined in the discriminant band. Dividing into a medium density region, a high density region outside the upper curve, and a low density region outside the lower curve;
In contrast to the distribution of the measurement results regarding the comparison sample, the calibration sample and the comparison sample are selected based on the ratio of the measurement results regarding the calibration sample included in the high density region or the low density region. Determining a first threshold value, and determining a second threshold value for determining that the sample is a calibration sample from a ratio of measurement results relating to the calibration sample included in the medium density region;
Irradiating the sample to be selected with the two X-rays to measure the intensity of transmitted X-rays per unit area;
Classifying the two measured X-ray intensity values per unit area into the high density region, the medium density region, and the low density region;
When the ratio included in the high-density area or the low-density area is smaller than a predetermined first threshold value and the ratio included in the medium-density area is larger than a predetermined second threshold value, the sample to be sorted is a product to be collected. A step of determining
Aluminum alloy identification method.   In the procedure of irradiating two X-rays having different intensities, the object to be measured is irradiated by one X-ray source, and the X-rays transmitted through the object to be measured are measured by two X-ray detection linear sensors. The X-ray detection linear sensor is covered with a shielding plate that absorbs a part of the X-rays, so that the same effect as when X-rays having different intensities are irradiated is obtained. Item 2. The aluminum alloy discrimination method according to Item 1. A belt conveyor for conveying a sample to be sorted of aluminum and aluminum alloy;
An X-ray source device provided above the belt conveyor;
Two X-ray detection linear sensors arranged in parallel with two X-ray detection linear sensors provided under the belt conveyor to measure the intensity of transmitted X-rays, and one X-ray detection linear sensor is a sensor An X-ray sensor that transmits through a shielding plate that is covered with light and weakens the X-ray intensity to detect the X-ray sensor;
Using the outputs of the two X-ray sensors, the intensity of transmitted X-rays per unit area at the same position of the sample is calculated based on the transport distance of the belt conveyor, and the two X-ray intensities per unit area are calculated. The high-density region is classified into a high-density region, a medium-density region, and a low-density region that can be selected from the second aluminum alloy that has been calibrated in advance using a calibration sample of the first aluminum alloy. Alternatively, when the ratio included in the low density region is smaller than a predetermined first threshold value and the ratio included in the medium density region is larger than a predetermined second threshold value, it is determined as the first aluminum alloy and measured. A determination device for generating a command to distribute the first aluminum alloy to the first storage tank and the other aluminum alloy to the second storage tank according to the determination result when the end position of the belt conveyor is reached;
An X-ray transmission type metal sorter having a distribution device for distributing the sample to the selection target side and the non-target side in accordance with a command of the determination device;
Pretreatment equipment for sorting and recovering aluminum and aluminum alloy waste from other waste and supplying it to the belt conveyor of the X-ray transmission type metal sorter;
Aluminum alloy sorting equipment equipped with. The pretreatment equipment is
A metal sorter that supplies metal waste by removing non-metallic items from waste of a predetermined size or more supplied by sieving;
The aluminum alloy sorting equipment according to claim 3, further comprising an aluminum sorter that sorts and supplies aluminum and an aluminum alloy from the metal waste supplied from the metal sorter.   The said aluminum sorter calculates the intensity | strength of the transmission X-ray for every unit area in the same position of a sample based on the conveyance distance of a belt conveyor using the output of a double X-ray sensor, When the X-ray intensity is placed on the measurement plane and placed in a higher density area than the discriminant curve obtained by calibrating in advance using a calibration sample for aluminum and aluminum alloy, it is judged as a metal other than aluminum and aluminum alloy. The aluminum alloy sorting equipment according to claim 4, which is still another X-ray transmission type metal sorter to be eliminated.