RU2808530C1 - Method and system for sorting diamonds - Google Patents

Abstract

FIELD: sorting diamonds.

SUBSTANCE: essence of the invention lies in the fact that a sample of material, including diamonds, is transported through a transport system containing a conveyor belt; emitting x-rays via an x-ray source onto a sample of the material; measuring the intensity of the emitted X-ray radiation from the material sample by means of an X-ray luminescence (XRL) detector placed around the conveyor belt; measuring the intensity of X-ray transmission through the sample material by means of an X-ray transmission (XRT) detector located under the conveyor belt; and receiving, through the processor, measurements of emitted radiation intensity and transmitted radiation intensity from the XRL detector and the XRT detector, respectively; processed by a processor to measure the intensity of the emitted radiation and the intensity of the transmitted radiation to determine the equivalent absorption coefficient; and identifying the material sample or portion of the material sample as diamond based on a comparison of the equivalent absorption coefficient with the previously stored absorption coefficient of the reference sample.

EFFECT: increasing the reliability of detection of diamond particles.

10 cl, 6 dwg

Description

Field of technology to which the invention relates

[0001] This invention relates to diamond sorting and, in particular, relates to X-ray sensor-based methods and systems for identifying and sorting partially/fully released diamonds in kimberlite.

State of the art

[0002] Sorting of diamonds (and other gemstones) is necessary to separate synthetic materials from natural ones. Currently known X-ray systems and methods for sorting diamonds are machines based on X-ray transmission scanning (XRT) Tomra, De Beers technology (XRT and X-ray luminescence - XRL) and Bourevestnik (XRL and XRT). All such systems currently in existence are based on a carbon signature using atomic density as a detection method.

[0003] Currently, the two sorting technologies mentioned (XRT and XRL) are used in a mutually exclusive manner for the following reasons. First, XRL measurements are affected by self-absorption in the case of large diamonds, such as larger than 10 mm, and the self-absorption phenomenon is aggravated at high X-ray energies. XRL measurements are typically used for diamonds smaller than 10mm, typically between 1.25mm and 8mm. Second, XRT measurements have low contrast for particles in the 1.25 mm to 8 mm size range, making it difficult to detect particles in this class. In general, XRT has a negative impact on the recovery of diamonds in the sub-8mm size range.

[0004] In addition, for sorting large materials ranging in size from 1.25 mm to 100 mm, existing methods usually require two machines, i.e. one XRT machine and one XRL machine, which can significantly increase sorting costs.

[0005] Accordingly, there is a need for a system that solves the self-absorption and contrast problems discussed above, as well as a low-cost sorting solution.

Disclosure of the Invention

[0006] This invention relates to sorting a mass of particles into desirable and undesirable fractions. In one application of the invention, it can be used to sort a mass of ore particles into desirable and undesirable fractions. One particular application of the invention is to sort into diamonds or diamond-containing material and non-diamond or non-diamond containing material.

[0007] The present invention aims to provide a solution to all of the above problems by providing an integrated system for sorting/identifying diamonds.

[0008] According to one embodiment of the present invention, a system for sorting diamonds is provided. The system comprises a transport system comprising a conveyor belt for transporting a sample of material including diamonds. In addition, the system includes an x-ray source configured to emit x-rays onto the material sample. In addition, the system includes an X-ray luminescence (XRL) detector located around the conveyor belt, configured to measure the intensity of emitted X-ray radiation from the material sample. In addition, the system includes an X-ray transmission (XRT) detector located under the conveyor belt, configured to measure the intensity of X-ray transmission through the sample material. The system also contains a processor that is configured to: receive measurements of the intensity of emitted radiation and the intensity of transmitted radiation from the XRL detector and the XRT detector, respectively; processing the intensity of emitted radiation and the intensity of transmitted radiation to determine the equivalent absorption coefficient; and identifying a sample of material or a portion of a sample of material as diamond based on a comparison of the equivalent absorption coefficient and the previously stored absorption coefficient of the reference sample.

[0009] The processor may be configured to process the emitted radiation intensity and transmitted radiation intensity measurements by inverting each of the emitted radiation intensity and transmitted radiation intensity measurements.

[0010] The x-ray source may be configured to emit x-rays at a predetermined detection zone on the conveyor belt. The x-ray source may be configured to emit x-rays into a predetermined detection zone at a single energy level.

[0011] The system may further comprise an x-ray generator, wherein the x-ray generator is configured to apply a sequence of step-up voltage signals to the x-ray source. The x-ray source may be configured to emit x-rays into a predetermined detection zone at a plurality of energy levels corresponding to a sequence of step-up voltage signals. The plurality of energy levels may correspond to a sequence of energy levels ranging from 1 keV to 150 keV.

[0012] To identify a material sample as diamond, the processor may be configured to determine that the result of a comparison between the equivalent absorption coefficient and the pre-stored absorption coefficient of the reference sample is within a predetermined range.

[0013] The system may further comprise a pneumatic ejector, wherein the pneumatic ejector is configured to eject at an (x,y) coordinate of the conveyor belt in response to identification of the material sample as diamond.

[0014] The invention extends to a method for sorting diamonds, the method comprising the steps of:

transporting, through a transport system containing a conveyor belt, a sample of material including diamonds;

emitting x-rays via an x-ray source onto a sample of the material;

measured by an X-ray luminescence (XRL) detector placed around the conveyor belt, intensity

X-ray emission from a sample of material;

measuring, by means of an X-ray transmission (XRT) detector located under the conveyor belt, the intensity of X-ray transmission through the sample material; And

receiving, through a processor, measurements of emitted radiation intensity and transmitted radiation intensity from the XRL detector and the XRT detector, respectively;

processed by a processor to measure the intensity of the emitted radiation and the intensity of the transmitted radiation to determine the equivalent absorption coefficient; And

identifying a sample of material or a portion of a sample of material as diamond based on a comparison of the equivalent absorption coefficient with a previously stored absorption coefficient of the reference sample.

Brief description of drawings

[0015] Certain embodiments of the present invention are illustrated by way of example and are not limited to the diagrams or measurements in the accompanying drawings, in which like symbols may indicate like elements, and in which:

[0016] In FIG. 1 depicts a system 100 for identifying and sorting partially/fully released diamonds in kimberlite in accordance with various embodiments of the present invention.

[0017] In FIG. 2 illustrates a segmented conveyor belt in accordance with some embodiments of the present invention.

[0018] In FIG. 3 depicts a projection of x-ray radiation onto detection elements in accordance with some embodiments of the present invention.

[0019] In FIG. 4 depicts a timing diagram for projecting x-ray radiation onto detection elements in accordance with some embodiments of the present invention.

[0020] FIG. 5 illustrates a method for identifying and sorting partially/fully released diamonds in kimberlite in accordance with various embodiments of the present invention.

[0021] FIG. 6 illustrates an exemplary computer program product that is configured to provide diamond sorting/identification in accordance with various embodiments of the present invention.

Carrying out the invention

[0022] The present invention will now be described with reference to the accompanying drawings, which represent exemplary embodiments.

[0023] Several exemplary aspects of the present invention will now be described with reference to the drawings. The word “exemplary” is used herein to mean “serving as an example, example, or illustration.” Any aspect described herein as “exemplary” should not necessarily be construed as preferable or superior to other aspects.

[0024] In accordance with various embodiments of the present invention, material (eg, kimberlite rock) that is expected to contain diamonds and gangue is introduced into the diamond sorting apparatus through a mixing/feed chute. The purpose of the mixing/feed chute is to ensure that no two particles are on top of each other. The particles fall freely into the mixing/feed chute and reach a speed equal to the speed of the system's conveyor belt. This is done in order to prevent particles from jumping up and reaching the detection zones while there is still relative motion between them and the conveyor. A conveyor belt transports particles to the detection area.

[0025] The detection zone consists of an X-ray luminescence (XRL) detector with a plurality of sensors covering the entire cross-section of the conveyor belt, and an X-ray transmission (XRT) detector with a plurality of sensors covering the entire cross-section of the belt. The XRL detector is placed at a suitable angle above the conveyor belt or placed at right angles to the free-fall path of the material. The transmission detector is located directly under the conveyor belt.

[0026] The X-ray source is placed vertically above the XRT detector, while the XRL detector is positioned at a suitable angle from the normal between the XRT detector and the X-ray sources. Each of the two detectors captures the radiation intensity from the sample. If geometry does not allow due to the physical dimensions of the device body, two X-ray sources can be used in such a way that each detector is associated with its own source. The measured intensities from the two detectors are inverted to obtain the equivalent absorption coefficient by using an algorithm in the processing block. Next, the inversion results in the processing block are summed up to obtain the final calculated absorption coefficient.

[0027] Before starting work, a series of measurements are performed using real diamonds to obtain the measured absorption coefficient during the calibration process. During calibration, X-rays with energies ranging from 1 keV to 150 keV are emitted onto the samples. The result is equivalent intensity measurements in the luminescence and transmission modes. The values are stored in processor memory for use as a reference for comparison. These values are called the reference sample absorption coefficient. The absorption coefficients for the two reference samples are combined through nonlinear addition, and the result is used as a baseline to determine what is diamond and what is not.

[0028] During operation, samples are supplied to the detection zone and the absorption coefficient from the two sensors is calculated. The combined measured absorbance is compared with the stored calibrated data to determine the level of similarity. If the correlation is 65%-100% for any given particle, then that particle can be classified as a diamond and is moved to a collection chamber or product collection chute where it will later be sorted by human sorters. If the similarity level is less than 65%, then the material in the detection zone can be considered gangue (or non-diamond) and is allowed to enter the reject stream or product reject chute.

[0029] Since the quality and characteristics of diamonds can vary due to the amount of impurities present, a calibration process is performed for a specific diamond tube to optimize production. The minimum similarity constraint is optimized based on the level of return acceptable to the owner. The system has two sorting operating modes, including monochromatic and polychromatic sorting. Using values measured by irradiating samples with X-ray energies ranging from 1 keV to 150 keV, it is possible to determine the optimal energy point that allows the sorter to operate at one energy level (monochromatic). This mode is available to the user if there is an advantage in working with high throughput without compromising sorting quality. The sorter can also operate in polychromatic mode, in which all displayed values from 6 keV to 150 keV for a reference sample are compared with measured values for a sample in the same range.

[0030] In FIG. 1 depicts a system 100 for identifying and sorting partially/fully released diamonds in kimberlite in accordance with various embodiments of the present invention. System 100 includes housing/shell 102, feed chute 104, conveyor belt 108, motor and drive pulley 110, tail pulley 112, variable speed drive 114, device 134, controller 116, signal processor 118, x-ray generator 120, x-ray source 122 radiation, detectors 124 and 126, product collection chute 128, product rejection chute 130 and pneumatic ejector 132.

[0031] The system 100 is enclosed in a housing/shell 102. The housing/shell 102 may be made of a material that provides physical protection to the equipment of the system 100 from the external environment and attenuates x-ray radiation, thereby limiting any radiation exposure to the user/operator during operation system 100. The housing/enclosure 102 may be designed in accordance with the rules/regulations of the country in which the system 100 is to be operated. In accordance with an exemplary embodiment of the present invention, the housing/enclosure 102 is a metal enclosure that can limit human exposure to the system 100 during normal operation.

[0032] For additional safety and protection regarding any human exposure to radiation, all doors, panels, or access points (not shown) of the system 100 may be monitored by one or more sensors (not shown), and x-rays may not be generated by the x-ray generator 120 until until the sensors detect complete closure of the housing/shell 102. One or more sensors may be communicatively coupled to a controller 116, which in turn controls the operation of the x-ray generator 120. In addition, during operation of the system 100, the system 100 may be configured to illuminate a strobe light (not shown) that provides an indication that x-rays are being generated and that the system 100 is in an operating state.

[0033] System 100 may be coupled to a feed system (not shown) containing a feed chute 104 for feeding material 106a/106b (e.g., kimberlite) including diamonds to identify and/or sort partially/fully released diamonds from the feed. material 106a/106b. In an exemplary embodiment of the present invention, the feed system may be, for example, but not limited to, a vibrating bowl feeder or a mesh feeder to provide a continuous supply of material 106a/106b to the conveyor belt 108. One skilled in the art will appreciate that the feed chute 104 may be configured to mix material 106a/106b along the conveyor belt 108 to prevent particles of material 106a/106b from stacking on top of each other. In addition, the feed chute 104 is configured to prevent relative motion between the particles of material 106a/106b and the feed belt as the particles approach the detection zone 136 of the conveyor belt 108.

[0034] The system 100 may further comprise a conveyor system that includes a conveyor belt 108, a motor and drive pulley 110, a tail pulley 112, and a variable speed drive 114. The conveying system is configured to operate at a reference speed that is received as a signal at the variable speed drive 114 from the controller 116. In addition, the system 100 includes a device 134 (e.g., a tachometer) for measuring the current speed of the conveyor belt 108. The device 134 transmits the measured the speed of the conveyor belt 108 back to the controller 116, and the controller 116 in turn controls that the conveyor belt 108 is driven at the speed desired for proper operations. Continuous measurement/monitoring of the speed of the conveyor belt 108 by the device 134 also ensures that there is no slippage of the conveyor belt 108. If slippage of the conveyor belt 108 is detected, the operation of the system 100 is immediately stopped by the controller 116.

[0035] According to various embodiments of the present invention, the conveyor belt 108 can be substantially segmented at a specific position y by dividing x _i into equal lengths to identify the position of each sample of material supplied to the conveyor belt 108. The detection zone 136 has pixelated or individual zones detection sufficient to cover the entire belt portion in the transverse direction since the conveyor belt 108 moves in the y direction. This segmentation may be imaginary in relation to the conveyor belt 108. In an exemplary embodiment of the present invention, the segmentation may be provided on a line scan camera placed under or above or at 90°. The actual size of the detection zone 136 in length depends on the smallest particle size that is intended to be detected. This is clearly shown in Fig. 2. A sample of material will be presented to the detection zone 136 when the sample reaches the (x _i , y) coordinate. As may be appreciated by one skilled in the art, while in FIG. 2 shows a pattern present at one particular length division x _i , the pattern may overlap any number of x _i in accordance with other embodiments of the present invention.

[0036] The system 100 may further include an x-ray generator 120 including a high voltage transformer (not shown). In an exemplary embodiment of the present invention, the high voltage transformer may be configured to receive a 220V AC input on the low voltage side of the transformer and output a step-up voltage, preferably, but not limited to, on the order of 1 keV to 150 keV. The stepwise output voltage is supplied to the x-ray source 122. The gain level through the high voltage transformer is achieved through a tap changer. Control of the tap changer is provided by a signal received from the controller 116. The signal is a fast pulse signal whose function is to switch the state of the tap changer from low to high.

[0037] Voxel ν(x,y)=I(E,x,y)=<100>, where <100> is a data set containing 100 observation points as the voltage increases from 6 keV to 150 keV. It takes time t _Ei to complete the observation point I(E _i ,x,y), while the time to change states from E _i to E _i+1 is 2t _s , at time t _s -t _Ei processor 118 performs the calculation μ (E _i ,ν(x,y)) and saves it. While the number of observation points is determined to be 100, one skilled in the art will appreciate that the number of observation points can be any given number and the system 100 can be configured accordingly.

[0038] More specifically, the sample can be substantially segmented by pixels of the line scan camera, as explained above. At point x,y a rectangular section of the sample can be taken, which is called a voxel.

ν(x,y)≡I(E,x,y)=<100>.

[0039] For each rectangular section, a number of samples can be irradiated with X-rays in the range from 1 keV to 150 keV. The interval 1 keV - 150 keV will be divided into 100 small subsections. In an exemplary embodiment of the present invention, the voltage will be increased in steps from 1.5 keV to 150 keV. This X-ray radiation is emitted at this one point voxel ν(x,y) or simply coordinate (x,y). Thus, for every single point voxel there are 100 data points. Accordingly, in this case, for the set I _i ={I ₁ , I ₂ …I ₁₀₀ }, each detector 124 and 126 will make measurements at its output I ₀ ={I _o1 , I _o2 …I _o100 }.

[0040] It should be noted that μ∝I ₀ /I ₁ , therefore there will be 100 μ values for each of (x, y). The purpose of this irradiation and data collection is to perform a determination of the equivalent absorption coefficient X of the extended X-ray absorption fine structure (EXAFS) in polychromatic mode. As described above, polychromatic mode is defined by the system operating at different energy levels created by increasing the voltage from 1 keV to 150 keV.

[0041] The main purpose of this action is to solve the following equation:

where k are voltage/energy levels from 1 keV to 150 keV.

The object of the present invention is to obtain 100 samples of χ(k) by exposing the sample to 100 x-ray voltages and/or energies ranging from 1 keV to 150 keV and measuring the corresponding output intensities for the corresponding voltage levels and making a comparison to obtain one hundred χ values of the equivalent EXAFS absorption coefficient.

[0042] Based on the collected/determined 100 χ values, the following steps are performed:

- comparison of the graph χ from an unknown sample and χ _m , where χ _m is a set of 100 values stored in memory, measured for a known sample (in this case, diamond). System 100 is calibrated on real diamonds. χ _m can be obtained by irradiating diamonds with X-ray energies in the range from 1 keV to 150 keV;

- the Fourier transform χ can also be performed, and its result will consist of two points or graphs;

- the amplitude information is proportional to ƒ _j (k) and the phase information 2kr _j +δ _j (k) and 2kr _j +δ _j (k) are unique to the sample of atoms j (diamonds in the present invention);

- comparison with trends of ƒ _m (k) and 2kr _m +δ _m (k) atomic models is also necessary, which will also be obtained through a calibration process on real diamonds.

[0043] The system 100 further includes an x-ray source/tube 122 configured to pulse via accelerating voltages in the range of 1 keV to 150 keV. In turn, the X-ray source 122 is configured to generate/emit X-rays in the appropriate range from 1 keV to 150 keV. The X-ray source/tube 122 may be cooled by heat generated by the collision of photoelectrons with the anode.

[0044] The system 100 further includes at least two detectors, i.e. detector 124 and detector 126. Detector 124 may be an XRT sensor that is configured to capture x-rays transmitted through the sample. According to one embodiment of the present invention, detector 124 may include a charge coupled device. According to another embodiment of the present invention, detector 124 may include a scintillation array of cells that are excited to produce a current upon interaction with x-ray radiation. The XRT sensor may have a number of terminals that map to each of the coordinates (x _i ,y) on the moving conveyor belt 108. The XRT intensity for a particle at (x _i ,y) for energy level E _j may be I _T (E _j , x _i ,y). This signal can be collected at the i output of detector 124 and transmitted to controller 116 via the i-th bus channel (not shown) between detector 124 and controller 116.

[0045] Detector 126 may be an XRL sensor that is configured to capture X-ray luminescence from sample 106b in detection zone 136. According to various embodiments of the present invention, detector 126 or XRL sensor may include either a scintillation cell array or charge coupled devices. The cell array may be configured to output current upon interaction with x-ray luminescence radiation received from sample 106b in detection zone 136. The sensor outputs may be mapped to coordinates (x _i ,y) on the moving conveyor belt 108. The XRT intensity for a particle at (x _i ,y) for energy level E _j may be I _L (E _j ,x _i ,y). This signal may be collected at the i output of detector 126, and it is transmitted to controller 116 via the i-th bus channel (not shown) between detector 126 and controller 116.

[0046] System 100 further includes a signal processor 118 that is configured to perform x-ray projection compensation normal to the plane of detector elements 124 and/or 126, as shown in FIG. 3.

[0047] The 90° radiation intensity directed at the sample is I ₀ .. If, for example, there are 2N+1 detection zones within zone 136, counting from the first pixel either to the left or to the right, the middle pixel will be at pixel N +1, and the transmitted radiation intensity associated with this point will be equal to I _N+1T :→I ₀ ,, (the measured intensity at N+1 is due to I ₀ ). Thus, the flux of X-ray radiation penetrating the material has an incident radiation intensity I ₀ .. However, for x-ray radiation at an angle θ to I ₀ , let the unit normal vector parallel to the flux I ₀ be equal to k ₀ , in addition, if defined, that I _θ is an X-ray beam parallel to the unit vector k _θ , the X-ray flux perpendicular to the pixel will be equal to:

[0048] Thus, for a pixel θ from the sample normal, the corresponding incident radiation flux intensity is equal to I ₀ cosθ. This is explained in more detail below.

[0049] It should be noted that for both luminescence and transmittance, the absorption coefficient χ is measured relative to I ₀ , where the angle to the normal of the detection pixel is collinear with the angle of the incident photoelectron flux from the x-ray source 122. All other pixels register the incident photoelectron flux at an angle.

[0050] The flux φ of any field F passing through a unit surface dS is defined as:

φ=F⋅dS=|F||dS|cos(θ)

[0051] Similarly, here F=I ₀ is the incident photoelectron flux, and dS=dS(x,y) is the pixel at position (x,y),

For the case when I ₀ and dS are collinear, θ=0,

Then φ=|I ₀ ||dS|cos(0)=I ₀

But if θ≠0,

φ=|I ₀ ||dS|cos(0)=I _o cos(θ)

For luminescence

To compensate, instead of using I ₀ as in the above equation, for pixels forming an angle with the source, I ₀ is replaced by I _o cos(θ).

[0052] The same applies to the transmission signal,

As noted above, one of the objects of the present invention is to obtain μ(E) by solving equations (3) and (4) and sharing the results.

[0053] It should be noted that

μ(E)=μ _o (1+χ(E))

According to an embodiment of the present invention, χ(E) (which is the EXAFS equation) is subsequently determined. Thus, essentially, the EXAFS data is derived from luminescence and transmittance measurements, which in turn are obtained from detectors 124 and 126.

[0054] According to an embodiment of the present invention, if the luminescence results from the EXAFS data are determined to be χ _L (E) and the transmittance results from the EXAFS data are determined to be χ _T (E), then the equivalent absorption coefficient (final EXAFS data) will be:

χ(E)=χ _L (E)+χ _T (E).

[0055] According to an exemplary embodiment of the present invention, the x-ray radiation incident and collinear to the normal of the central pixel/scintillator/channel is χ _N , and all other x-ray radiation deflects at an angle {φ} to the normal to the scintillator plane. Signal processor 118 performs compensation to ensure that all x-rays are brought to baseline.

[0056] The array represents the intensity of x-rays emitted by pulses from E=6 keV - 80 keV.

Signal processor 118 performs two complementary tests. In some embodiments of the present invention, a single test is sufficient to perform the desired sorting program to identify diamonds from material sample 106a/106b. The first test is a comparison with {I ₀ (E=60 keV)}. The second test involves comparing the array { _Iφi (E)} with an array for a reference sample stored in advance in the signal processor 118, such as a reference sample array for (diamond).

[0057] In the first test, which is a monochromatic test, the test criteria are defined:

{I _φi (E)}={I _φƒ (E)/I ₀ (E)}+{1п{I ₀ (E)/I _φТ (E)}}

[0058] In the second test, the polychromatic test, the criteria are:

(EXAFSα|EXAFSm),

where (x|y) is the cross-correlation coefficient of data x and y. Where the subscript α refers to the actual measured data and the subscript m represents the calibrated data for the target sample in the set {E}.

[0059] Signal processor 118 may be calibrated using carbon (diamond) EXAFS reference data for both luminescence and transmittance. In this embodiment, the received EXAFS data may be the arithmetic sum of luminescence data and transmittance data received from detectors 124 and 126.

[0060] The intensity measurements I _φTi (E) and I _φƒi (E) are inverted, respectively, into EXAFS data of the sample/particle. The numerical sum of the resulting EXAFS data is correlated with the resulting EXAFS reference data.

[0061] A predetermined criterion/threshold value for the similarity between the resulting EXAFS data and the EXAFS reference data may be stored in the signal processor 118. According to one embodiment of the present invention, plots of the EXAFS summary data and the EXAFS reference data can be plotted, and a similarity index based on the comparison of the two data is obtained. A threshold value for the similarity index may be set and stored in the controller 116 and/or signal processor 118. The test result can be compared with a given criterion/threshold value. If the criterion/threshold for the test(s) is reached, the diamonds are sorted/identified. For example, if the similarity index exceeds a predetermined threshold value of 65%, the material sample 106a/106b may be identified as diamond.

[0062] In another exemplary embodiment of the present invention, the test may be performed by using the Kolmogorov-Smirnov test to quantify the distance between two empirical EXAFS data sets. If the distance is very small, then the similarity is good. The same way,

Similarity=1-D _KS

[0063] D _KS (Kolmogorov-Smirnov distance) is measured between two EXAFS data. In addition, the material sample 106a/106b can be identified as diamond if _DKS is obtained around zero, and thus the similarity is around 1. As will be appreciated by one skilled in the art, _DKS is user configurable.

[0064] A signal corresponding to the result may be sent from the signal processor 118/controller 116 to the pneumatic ejector 132. Specifically, when the result corresponds to the detection of diamond in the material sample at the (x, y) coordinate of the conveyor belt 108, the pneumatic ejector 132 ejects at the specified coordinate, thereby turning the diamonds into projectiles in the product collection tray 128. Thus, based on the positive result and the corresponding signal, the diamonds are thrown into the product collection chute 128. Likewise, based on the negative result and the corresponding signal, the system is configured to not eject from the pneumatic ejector 132, and the material sample 106a/106b is automatically ejected into the product rejection chute 130. One skilled in the art will appreciate that the pneumatic ejector 132 may be configured to eject in the event of a negative result, i.e. when the material sample 106a/106b is not detected to be diamond, to allow the material sample 106a/106b to be collected into the product rejection chute 130.

[0065] The system 100 further includes a controller 116 that is configured to transmit and receive signals between various elements of the system 100. Based on the signals transmitted and received by the controller 116, the system 100 performs various necessary functions as described herein.

[0066] The various signals to and from the controller 116 can be classified primarily into input and output signals. In addition, the input signals may include signals from the detector 124 via an N-channel bus (not shown) via an analog input board (not shown) as raw current data; signals from detector 126 via an N-channel bus (not shown) via an analog board (not shown) as raw current data; signals from processor 118 signals for instructions for general control of system 100; signal from device 134; signals from X-ray generator 120; and signals from VSD 114. Likewise, output signals may include a signal to x-ray generator 120; signals to pneumatically actuated ejector/selector 132; speed reference signal on VSD. In some embodiments of the present invention, the set point and control of the conveyor belt 108 may be programmed into the VSD 114. In other embodiments of the present invention, the overall control loop is controlled by the controller 116.

[0067] Depending on the desired configuration, the controller 116/signal processor 118 may be of any type, including, but not limited to, a microprocessor (μP), a microcontroller (μC), a digital signal processor (DSP), or any combination thereof. The controller 116/signal processor 118 may include one or more caching layers, such as a first level cache and a second level cache, a processor core, and registers. An example processor core may include an arithmetic logic unit (ALU), a floating point unit (FPU), a digital signal processing core (DSP core), or any combination thereof. An example memory controller may also be used with controller 116/signal processor 118, or in some implementations, the memory controller may be internal to controller 116/signal processor 118.

[0068] Depending on the desired configuration, system memory may be included in the controller 116/signal processor 118. System memory can be of any type, including, but not limited to, volatile memory (such as RAM), nonvolatile memory (such as ROM, flash memory, etc.), or any combination thereof. System memory may include an operating system, one or more applications, and program data. The system memory may further include a document interaction estimation algorithm that is configured to perform the functions described herein, including the functions described with respect to the system 100 of FIG. 1.

[0069] System memory may be implemented by removable storage devices and non-removable storage devices, which are examples of computer storage media. Computer storage media includes, but is not limited to, random access memory, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVDs) or other optical media, magnetic cassettes, magnetic tape, magnetic disk drive or other magnetic storage devices, or any other medium that can be used to store the desired information and that can be accessed by the controller 116/signal processor 118. Any such computer storage medium may be part of the controller 116/signal processor 118.

[0070] System 100 further includes a pneumatic ejector 132. The pneumatic ejector 132 or ejection system may include air solenoid valve assembly means. Geometrically, one solenoid valve can close N channels, or in some embodiments, especially for large particle systems, one or two solenoid valves are dedicated to a specific position (x _i ,y). The solenoid valves assigned to (x _i ,y) are actuated by the output signal of the i controller via the bus between the controller 116 and the pneumatic ejector 132.

[0071] The system 100 further includes a product collection chute 128 and a product rejection chute 130. These two chutes 128 and 130, respectively, are configured to transport sorted diamonds and remaining material from the material sample 106a/106b. The chute 128 may lead to a human manual sorting station (not shown) where further processing of the sorted/identified diamonds occurs. Likewise, chute 130 may be configured to transport material to another conveyor belt system in which the remaining material/material sample 106a/106b may be processed.

[0072] In operation, the system 100 receives an input material sample 106a/106b from a supply system (not shown). The material sample 106a/106b enters the conveyor belt 108 through the feed chute 104. The material sample 106a/106b is then transported to the detection zone 136. The speed of the conveyor belt is controlled by a motor 110 driven by a variable frequency drive 114 that receives a speed signal from a controller 116. In addition, the current belt speed is continuously measured/monitored by a device 134 (e.g., a tachometer) and transmitted to the controller 116 via a corresponding signal. The system 100 may be further configured to stop its operation if the device 134 does not output a signal corresponding to the current speed. The controller 116 controls the increase in accelerating voltage by amplifying a transformer included in the x-ray generator 120, which in turn supplies the x-ray source 122 with a high voltage to generate x-rays from 6 keV to about 80 keV. The generated x-ray radiation is passed through the material sample 106a/106b in the detection zone 136.

[0073] In addition, data or luminescence measurements corresponding to the luminescence produced by the material sample 106a/106b in the detection zone in response to the transmission of x-rays is captured by the detector 126. Also, detector 124 captures data or transmittance measurements that correspond to the x-rays transmitted through a sample of material 106a/106b in the detection zone 136. The signal processor 118 is configured to store threshold criteria for what is diamond and what is not. More specifically, the signal processor may be configured to store two different types of data criteria, such as monochromatic data and polychromatic data. Signal processor 118 projects the x-ray radiation normal to the detector plane, compensating for signals from either detector, and calculates the result of adding the direct luminescence contrast coefficient and the inverse logarithm of the transmittance data in monochromatic space. The actual data is then compared with the previously stored data/criteria. The X-ray is increased from 1 keV to 80 keV in a cycle that ensures that the sample data is captured, analyzed, and determined to contain diamond in the material sample 106a/106b such that there are no material gaps in the sample between clock periods. Data values at 60 keV are selected from the entire array to ensure monochromatic testing. Input calibrated data is stored in processor 116 that includes EXAFS trends of a reference element (eg, carbon) at various energy values. A correlation of the actual trend between the sample and the reference element is performed to establish the level of similarity and thereby identify the diamonds. A statistical evaluation is performed and a determination is made based on the level of similarity.

[0074] According to various embodiments of the present invention, this approach takes advantage of variations in measured radiation intensity for both luminescence I _L and transmittance I _T and defines a new parameter, which is a surrogate absorption coefficient of the material, by performing a non-linear addition of the following relationships (discussed below), which is independent of thickness and energy. In addition, the approach described above is applicable to both monochromatic and polychromatic sorting discussed in this document. In polychromatic sorting, EXAFS measurements are obtained from I _o versus I _L and I _o versus I _T . The present invention includes providing a polychromatic x-ray source 122 in which one data point can be used for monochromatic sorting and the entire set can be used for polychromatic sorting.

[0075] Based on the problem of self-absorption control, for a large material sample 106a/106b, luminescence data at 150 keV can be taken into account, otherwise other size ranges of material samples will be irradiated with any energy from 1 keV to 150 keV.

[0076] MONOCHROMATIC SORTING - luminescence coefficient and transmittance are used to define a new parameter μ. This follows from the following:

which is the equation for the luminescence intensity at detector 126. The above equation must be solved for μ _χ (E), but μ _tot (E) is also a function of μ _χ (E), which makes this equation a transcendental equation that is difficult to solve directly except using the Newton-Rapson approach. Typically, to solve the above equation, simplifying assumptions are taken into account, which are based on two aspects.

Thickness t - composition of sample 106a/106b material, i.e. whether the sample is pure, has a balanced concentration, or is diluted.

“Pure” means μ _tot /(E)=μχ(E),

"balanced" means μ _tot (E)=μχ(E)+μ _other (E), where μ _other (E) means impurities.

Thickness Assumptions—In various embodiments of the present invention, X-ray energy is used at 60 keV, which is the optimal value at which material samples 106a/106b have a pronounced absorption coefficient.

Thin samples

those. t values from which the product is obtained

when this is the case, exponent

can be assessed as

Which allows us to rewrite equation (5) in the form:

Let's simplify to

Or

By inverting equation (6) to obtain μ _χ (E), the luminescence coefficient in the range of thin samples can be determined as:

Can then be measured while 4π/∈ΔΩ represent detector properties that themselves can be optimized to best measure μχ(E).

Consequence of the above condition:

e ^-x =1-x for x<0.4

To recover particulate diamonds, 70% diamond and 30% waste, this gives:

μ _tot (E ₆₀ )=μχ(E ₆₀ )+μ _other (E ₆₀ )=0.4933

x=0.4933t<0.4,

t<0.8190 cm=8.2 mm

The other extreme value is obtained from the approximation

e ^-x ≈0

This occurs when x>1.616 (this gives t>32 mm, for μ _tot (E=60 kV)=0.4933

This means that equation (5) can be estimated as

But the component is a function of energy E and causes a decrease, which causes a phenomenon called self-absorption.

The best x-ray energy value that gives the best intensity measurement under a thick sample is E=150 keV. This is identified as an important characteristic for reducing self-absorption when measuring luminescence intensity.

Geometric configuration of the XRL detector.

Here it is necessary that the member in was such that

According to various embodiments of the present invention, θ, that is, the incident X-ray radiation must be perpendicular to the sample, and φ, the exit angle, must be very small, π/12. This provides self-absorption correction for XRL measurements.

According to various embodiments of the present invention, this output provides the following:

t<8 mm and t>32 mm, unaccounted interval 10-32 mm. XRL works well for samples smaller than 10 mm while XRT does not, and XRT also works well for samples larger than 10 mm.

[0077] SORT BY XRT

Equation for sorting by XRT

Sorting based on intensity gradient for the entire range from 1.25 mm to 100 mm. Thin samples

I _T ≈I _o

Implying that in this area the disadvantage of XRT is poor contrast due to which creates a case of poor discrimination. Thus, in XRT, for good measurements without the influence of contrast, it is desirable that:

I _T ≤0.5I _o

A thin sample is also defined as less than 10 mm. This condition requires that the minimum possible thickness for XRT measurements be 10 mm.

Discovery Kits

[0078] GRADIENT SORTING METHOD

According to some embodiments of the present invention, certain derivatives of the XRT and XRL equations are satisfied:

which is greater than zero, but decreases depending on t,

By defining the new parameter Dμ _x (E) as

it can be determined that:

If is constant for all t, then

Dμ _x (E)=I _o μ _x (E)Ks

or

Dμ _x (E)=Ioμ _x (E)Ks

Thus, the combined derivative Dμ _x (E} is unique for each material sample 106a/106/b since μ _X (E) and Ks are unique for each material, thus, a sorting method is developed herein that simultaneously uses luminescence measurement and transmittance, and which covers the entire sorting range (1.25 mm to 100 mm), which overcomes the limitations of self-absorption and poor contrast.

[0079] FIG. 5 illustrates a method 200 for identifying and sorting partially/fully released diamonds in kimberlite in accordance with various embodiments of the present invention. The method may be performed by controller 116/signal processor 118.

[0080] At step 202, an input signal may be received to initiate operation of the system 100. The input signal may be input to a controller 116 and/or a signal processor 118 that is configured to directly interact with a user through a computing device. Examples of a computing device may include, but are not limited to, a server, a computer, a laptop computer, a tablet computer, etc.

[0081] At step 204, a speed reference signal may be generated and transmitted. The speed reference signal may be generated based on a given configuration of the system 100. The generated speed reference signal may be transmitted to a variable speed drive 114 to drive the conveyor belt 108 via the motor and drive pulley 110 and tail pulley 112. In an alternative embodiment, the speed reference signal speed can only be generated in response to detection that all doors, panels, or access points (not shown) of the system 100 are completely closed. As described above, closure may be detected by one or more sensors, and a corresponding signal may be received by controller 116/signal processor 118.

[0082] At step 206, a signal corresponding to the current speed of the conveyor belt 108 may be received. A signal corresponding to the current speed may be received from an input device 134 (eg, a tachometer). The received signal corresponding to the current speed may be compared with the reference speed signal transmitted at step 204, and if the difference between the two signals exceeds a predetermined threshold, a signal may be sent to the variable frequency drive 114 to stop operation. In addition, a signal to stop operation may also be transmitted if a signal corresponding to the current speed is not received.

[0083] At step 208, a signal may be transmitted to initiate and increase the accelerating voltage. The magnification signal may be transmitted to an x-ray generator 120, which in turn powers an x-ray source 122 to generate x-rays.

[0084] At step 210, input data signals or measurements corresponding to the detected luminescence and x-ray transmission may be received. In accordance with various embodiments of the present invention, luminescence and x-ray transmission data may be received from detectors 124 and 126 based on the x-ray transmission of the material sample 106a/106b.

[0085] At step 212, processing of the input data signals is performed. The processing is performed by projecting the x-ray radiation onto the normal to the detector plane, compensating the signals from any of the detectors 124 and 126, and by calculating the result of adding the direct luminescence contrast coefficient and the inverse logarithm of the transmittance data in monochromatic space.

[0086] At step 214, a determination is made whether the processed signals correspond to diamonds, thereby identifying/sorting the diamonds in the material sample 106a/106b. Steps 212 and 214 may collectively include all of the steps discussed above with respect to FIG. 1 for signal processing. Based on the processing at step 212, the actual data is compared with the previously stored data/criteria. The X-ray is increased from 1 keV to 80 keV in a cycle that ensures that the sample data is captured, analyzed, and determined to contain diamond in the material sample 106a/106b such that there are no material gaps in the sample between clock periods. Data values at 60 keV are selected from the entire array to ensure monochromatic testing. Input calibrated data is stored in processor 116 that includes EXAFS trends of a reference element (eg, carbon) at various energy values. A correlation of the actual trend between the sample and the reference element is performed to establish the level of similarity and thereby identify the diamonds. A statistical evaluation is performed and a determination is made based on the level of similarity.

[0087] At step 216, one or more signals may be transmitted to a pneumatic ejector in accordance with various embodiments of the present invention to sort material into a product collection chute 128 and a product rejection chute 130.

[0088] FIG. 6 illustrates an exemplary computer program product that is configured to provide diamond sorting/identification, in accordance with at least some of the embodiments described herein. The computer program product 600 may correspond to a program product stored in the form of processor-executable instructions in the controller 116/signal processor 118.

[0089] Computer program product 600 may include signal media 604. Signal carrier 604 may include one or more instructions 602 that, when executed by, for example, a processor or controller, may provide the functionality described above for sorting/identifying diamonds from material sample 106a/106b.

[0090] In some implementations, signal media 604 may include computer-readable media 608, such as, but not limited to, a hard disk, compact disc (CD), digital video disc (DVD), digital tape, memory, etc. In some implementations, signal media 604 may include recordable media 610, such as, but not limited to, memory, read/write (R/W) CD, DVD R/W, etc. In some implementations, signal medium 604 may include communications media 606, such as, but not limited to, digital and/or analog communications media (e.g., fiber optic cable, waveguide, wireline, wireless link, etc.) . Thus, for example, software product 600 may be transmitted to controller 116/signal processor 118 via a radio frequency (RF) signal medium 604, wherein the signal medium 604 is transmitted via a wireless communication medium 606 (eg, a wireless communication medium compliant with the IEEE 802.11 standard).

[0091] It should also be noted that the operational steps described in any of the exemplary aspects herein are described to provide examples and discussion. The described operations may be performed in a variety of different sequences than those illustrated. In addition, operations described in one operational step may in fact be performed in many different steps. Additionally, one or more of the operational steps described in the exemplary aspects may be combined. It should be understood that the operational steps illustrated in the flowcharts are subject to many different variations as will be apparent to one skilled in the art. Those skilled in the art will also appreciate that information and signals may be represented using any of a variety of different technologies and techniques. For example, the data, instructions, commands, information, signals, bits, symbols and chips that may be mentioned throughout the above description may be voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination of them.

[0092] The above description of the invention is provided to enable any person skilled in the art to make or use the invention. Various variations of the invention will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments. Thus, the invention is not intended to be limited to the examples and designs described herein, but is intended to have the broadest scope consistent with the principles and novel features disclosed herein.

Claims (25)

1. A diamond sorting system, the system comprising: a transport system comprising a conveyor belt for transporting a sample of material including diamonds; an x-ray source configured to emit x-rays onto the material sample; an X-ray luminescence (XRL) detector located around the conveyor belt, configured to measure the intensity of emitted X-ray radiation from a sample of material; an X-ray transmission (XRT) detector located under the conveyor belt, configured to measure the intensity of transmitted X-ray radiation through the sample material; And a processor configured to: receiving measurements of emitted radiation intensity and transmitted radiation intensity from the XRL detector and the XRT detector, respectively; processing measurements of emitted radiation intensity and transmitted radiation intensity to determine the equivalent absorption coefficient; And identifying a sample of material or part of a sample of material as diamond based on comparison of the equivalent absorption coefficient with the previously stored absorption coefficient of the reference sample. 2. The system of claim 1, wherein the processor is configured to process the radiation intensity and transmission intensity measurements by inverting each of the radiation intensity and transmission intensity measurements. 3. The system of claim 1, wherein the x-ray source is configured to emit x-rays in a predetermined detection zone on the conveyor belt. 4. The system of claim 3, wherein the x-ray source is configured to emit x-rays in a given detection zone with one energy level. 5. The system of claim 3, further comprising an X-ray generator, wherein the X-ray generator is configured to supply a sequence of stepwise voltage signals to the X-ray source. 6. The system of claim 5, wherein the x-ray source is configured to emit x-rays into a predetermined detection zone at a plurality of energy levels corresponding to a sequence of step-up voltage signals. 7. The system of claim 6, wherein the plurality of energy levels correspond to a sequence of energy levels ranging from 1 keV to 150 keV. 8. The system of claim 1, wherein, in order to identify a sample of material as diamond, the processor may be configured to determine that the result of a comparison between the equivalent absorption coefficient and the pre-stored absorption coefficient of the reference sample is within a predetermined range. 9. The system of claim 1, further comprising a pneumatic ejector, wherein the pneumatic ejector is configured to eject at an (x,y) coordinate of the conveyor belt in response to identification of the material sample as diamond. 10. A method for sorting diamonds, the method comprising the steps of: transporting, through a transport system containing a conveyor belt, a sample of material including diamonds; emitting x-rays via an x-ray source onto a sample of the material; measuring, by means of an X-ray luminescence (XRL) detector placed around the conveyor belt, the intensity of the emitted X-ray radiation from the material sample; measuring, by means of an X-ray transmission (XRT) detector located under the conveyor belt, the intensity of X-ray transmission through the sample material; And receiving, through a processor, measurements of emitted radiation intensity and transmitted radiation intensity from the XRL detector and the XRT detector, respectively; processed by a processor to measure the intensity of the emitted radiation and the intensity of the transmitted radiation to determine the equivalent absorption coefficient; And identifying a sample of material or a portion of a sample of material as diamond based on a comparison of the equivalent absorption coefficient with a previously stored absorption coefficient of the reference sample.