CA2559516C - Detection of diamonds - Google Patents
Detection of diamonds Download PDFInfo
- Publication number
- CA2559516C CA2559516C CA2559516A CA2559516A CA2559516C CA 2559516 C CA2559516 C CA 2559516C CA 2559516 A CA2559516 A CA 2559516A CA 2559516 A CA2559516 A CA 2559516A CA 2559516 C CA2559516 C CA 2559516C
- Authority
- CA
- Canada
- Prior art keywords
- diamond
- particles
- particle
- photons
- carbon
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 239000010432 diamond Substances 0.000 title claims abstract description 110
- 238000001514 detection method Methods 0.000 title description 15
- 239000002245 particle Substances 0.000 claims abstract description 174
- 229910003460 diamond Inorganic materials 0.000 claims abstract description 100
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 54
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 54
- 238000000034 method Methods 0.000 claims abstract description 33
- 238000006243 chemical reaction Methods 0.000 claims abstract description 30
- 230000005251 gamma ray Effects 0.000 claims abstract description 22
- 238000004458 analytical method Methods 0.000 claims description 10
- 230000001678 irradiating effect Effects 0.000 claims description 9
- 230000000717 retained effect Effects 0.000 claims 1
- 230000003993 interaction Effects 0.000 abstract description 4
- 239000000463 material Substances 0.000 description 9
- 230000005461 Bremsstrahlung Effects 0.000 description 8
- 230000005855 radiation Effects 0.000 description 8
- 238000003384 imaging method Methods 0.000 description 7
- 230000004907 flux Effects 0.000 description 6
- 239000011435 rock Substances 0.000 description 5
- 230000032258 transport Effects 0.000 description 5
- 238000012545 processing Methods 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000000149 penetrating effect Effects 0.000 description 3
- 230000004913 activation Effects 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical group [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000002238 attenuated effect Effects 0.000 description 2
- -1 diamond Chemical compound 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 241000276420 Lophius piscatorius Species 0.000 description 1
- 238000003491 array Methods 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000011143 downstream manufacturing Methods 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 239000012634 fragment Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/22—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material
- G01N23/221—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material by activation analysis
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
- B07C5/00—Sorting according to a characteristic or feature of the articles or material being sorted, e.g. by control effected by devices which detect or measure such characteristic or feature; Sorting by manually actuated devices, e.g. switches
- B07C5/34—Sorting according to other particular properties
- B07C5/346—Sorting according to other particular properties according to radioactive properties
Abstract
The invention concerns a method and apparatus for detecting the presence of diamond in a particle and for sorting particles according to whether or not they include diamonds. In the method, the particle is irradiated (36) with photons of selected energy at which the GDR (giant dipole resonance) is excited for the nuclear reaction of the photons with carbon, and the particle is identified as potentially a diamond or diamond-containing particle according to its interaction within the incident photons. In the preferred embodiments, the particle is identified (42) as potentially a diamond or diamond-containing particle according to whether the isotope 11C, with a characteristic half-life of approximately twenty minutes, is produced by the photon/carbon nuclear reaction, and according to whether detectable coincident and collinear gamma ray photons at a distinctive energy level are emitted by the particle.
Description
"DETECTION OF DIAMONDS"
BACKGROUND TO THE INVENTION
This invention relates to the detection of diamonds.
The invention is applicable to the detection of diamonds as individual, free particles, as embedded in host bodies typically of kimberlite or as particles included in a mass of other particles.
Referring to the application of the invention in the detection of diamonds in host bodies of kimberlite it is recognised that it would be highly desirable in diamond recovery operations to have the facility to detect, at an early stage, kimberlite particles which are host to diamond inclusions. It would then be possible to reject the barren kimberlite particles and continue with processing of only those particles which are indicated as containing diamond inclusions.
With barren particles rejected at an early stage, the downstream processing equipment could have a reduced capacity requirement.
It would in addition be advantageous to have the facility to detect not only the presence of a diamond inclusion but also the size and relative position of that inclusion in the host kimberlite body, since this information could be used to regulate subsequent crushing operations used to liberate the diamond inclusion to ensure that it is not physically damaged.
CONFIRMATION COPY
BACKGROUND TO THE INVENTION
This invention relates to the detection of diamonds.
The invention is applicable to the detection of diamonds as individual, free particles, as embedded in host bodies typically of kimberlite or as particles included in a mass of other particles.
Referring to the application of the invention in the detection of diamonds in host bodies of kimberlite it is recognised that it would be highly desirable in diamond recovery operations to have the facility to detect, at an early stage, kimberlite particles which are host to diamond inclusions. It would then be possible to reject the barren kimberlite particles and continue with processing of only those particles which are indicated as containing diamond inclusions.
With barren particles rejected at an early stage, the downstream processing equipment could have a reduced capacity requirement.
It would in addition be advantageous to have the facility to detect not only the presence of a diamond inclusion but also the size and relative position of that inclusion in the host kimberlite body, since this information could be used to regulate subsequent crushing operations used to liberate the diamond inclusion to ensure that it is not physically damaged.
CONFIRMATION COPY
In known proposals for detecting a diamond inclusion in a host kimberlite body, the body is irradiated with X-radiation or with neutrons. In the former case, the differential absorption of X-rays by diamond and kimberlite provides an indication of the presence of a diamond inclusion. However this technique suffers from the disadvantage that there is a small difference only between the X-ray attenuation coefficient for diamond and the host kimberlite, so the contrast which is obtained is limited. Furthermore there is a severe limitation on the size of the particles which can be analysed in this way because of the substantial X-ray attenuation which takes place in kimberlite. The known neutron irradiation technique relies on neutron resonance absorption, but also has limitations insofar as detectable contrast between the diamond and the surrounding kimberlite rock, and complexity of the method in practice, are concerned.
SUMMARY OF THE INVENTION
One aspect of the present invention provides a method of detecting the presence of diamond in a particle, wherein the particle is irradiated with photons of selected energy at which the GDR (giant dipole resonance) is excited for the nuclear reaction of the photons with carbon, and identifying the particle as potentially a diamond or diamond-containing particle according to its interaction within the incident photons. The particle may be irradiated with bremsstrahlung encompassing a range of energy levels including a characteristic GDR energy level, typically 22MeV for carbon.
In the preferred embodiment, the particle is identified as potentially a diamond or diamond-containing particle according to whether the isotope "C, with a characteristic half-life of approximately twenty minutes, is produced by the photon/carbon nuclear reaction and/or according to whether coincident and collinear gamma ray photons at a distinctive energy level are emitted by the particle.
SUMMARY OF THE INVENTION
One aspect of the present invention provides a method of detecting the presence of diamond in a particle, wherein the particle is irradiated with photons of selected energy at which the GDR (giant dipole resonance) is excited for the nuclear reaction of the photons with carbon, and identifying the particle as potentially a diamond or diamond-containing particle according to its interaction within the incident photons. The particle may be irradiated with bremsstrahlung encompassing a range of energy levels including a characteristic GDR energy level, typically 22MeV for carbon.
In the preferred embodiment, the particle is identified as potentially a diamond or diamond-containing particle according to whether the isotope "C, with a characteristic half-life of approximately twenty minutes, is produced by the photon/carbon nuclear reaction and/or according to whether coincident and collinear gamma ray photons at a distinctive energy level are emitted by the particle.
According to another aspect of the invention there is provided an on-line particle sorting method comprising the steps of irradiating particles with photons of gamma radiation at an energy level at which GDR (giant dipole resonance) is excited for the nuclear reaction of the photons with carbon, identifying particles as potentially diamond or diamond-containing particles according to whether the isotope "C, with a characteristic half-life of approximately twenty minutes, is produced by the photon/carbon nuclear reaction and whether coincident and collinear gamma ray photons at a distinctive energy level are emitted by the particles, and separating from other particles those particles which are identified as potentially diamond or diamond-containing particles.
Still further the invention provides an apparatus for detecting the presence of diamond in a particle, the apparatus comprising means for irradiating the particle with photons of gamma radiation at a selected energy at which the GDR (giant dipole resonance) is excited for the nuclear reaction of the photons with carbon, and means for identifying the particle as potentially a diamond or diamond-containing particle according to the interaction of the particle with the incident photons.
The invention also provides an on-line particle sorting apparatus comprising irradiation means for irradiating particles which are to be sorted with photons of gamma radiation at an energy level at which GDR (giant dipole resonance) is excited for the nuclear reaction of the photons with carbon and identification means for identifying particles as potentially diamond or diamond-containing particles according to whether the isotope "C, with a characteristic half-life of approximately twenty minutes, is produced by the photon/carbon nuclear reaction and whether coincident and collinear gamma ray photons at a distinctive energy level are emitted by the particles, and means for separating from other particles those particles which are identified as potentially diamond or diamond-containing particles.
Still further the invention provides an apparatus for detecting the presence of diamond in a particle, the apparatus comprising means for irradiating the particle with photons of gamma radiation at a selected energy at which the GDR (giant dipole resonance) is excited for the nuclear reaction of the photons with carbon, and means for identifying the particle as potentially a diamond or diamond-containing particle according to the interaction of the particle with the incident photons.
The invention also provides an on-line particle sorting apparatus comprising irradiation means for irradiating particles which are to be sorted with photons of gamma radiation at an energy level at which GDR (giant dipole resonance) is excited for the nuclear reaction of the photons with carbon and identification means for identifying particles as potentially diamond or diamond-containing particles according to whether the isotope "C, with a characteristic half-life of approximately twenty minutes, is produced by the photon/carbon nuclear reaction and whether coincident and collinear gamma ray photons at a distinctive energy level are emitted by the particles, and means for separating from other particles those particles which are identified as potentially diamond or diamond-containing particles.
In accordance with an aspect of the invention, there is provided a method of detecting the presence of diamond in a particle, wherein the particle is irradiated with photons in an energy band window encompassing a characteristic value of about 22MeV at which the GDR (giant dipole resonance) is excited for the nuclear reaction of the photons with carbon, and identifying the particle as potentially a diamond or diamond-containing particle according to whether the isotope "C, with a characteristic half-life of approximately twenty minutes, is produced by the photon/carbon nuclear reaction.
In accordance with another aspect of the invention, there is provided an on-line particle sorting method including the steps of irradiating particles with photons is an energy band window encompassing a characteristic value of about 22MeV at which GDR (giant dipole resonance) is excited for the nuclear reaction of the photons with carbon, identifying particles as potentially diamond or diamond-containing particles according to whether the isotope "C, with a characteristic half-life of approximately twenty minutes, is produced by the photon/carbon nuclear reaction and whether coincident and collinear gamma ray photons at a distinctive energy level are emitted by the particles, and separating from other particles those particles which are identified as potentially diamond or diamond-containing particles.
In accordance with another aspect of the invention, there is provided an apparatus for detecting the presence of diamond in a particle, the apparatus including means for irradiating the particle with photons in an energy band window encompassing a characteristic value of about 22MeV at which the GDR (giant dipole resonance) is excited for the nuclear reaction of the photons with carbon, and identification means for identifying the particle as potentially a diamond or diamond-containing particle according to whether the isotope 11C, with a characteristic half-life of approximately twenty minutes, is produced by the photon/carbon nuclear reaction.
4a In accordance with another aspect of the invention, there is provided an on-line particle sorting apparatus including irradiation means for irradiating particles in an energy band window encompassing a characteristic value of about 22MeV at which GDR (giant dipole resonance) is excited for the nuclear reaction of the photons with carbon, identification means for identifying particles as potentially diamond or diamond-containing particles according to whether the isotope 11C, with a characteristic half-life of approximately twenty minutes, is produced by the photon/carbon nuclear reaction and whether coincident and collinear gamma ray photons at a distinctive energy level are emitted by the particles, and means for separating from other particles those particles which are identified as potentially diamond or diamond-containing particles.
Other features of the invention will appear from the following description and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Aspects of the invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:
Figure 1 diagrammatically illustrates an on-line sorting method according to an aspect of the invention;
Figure 2 diagrammatically illustrates the detection of coincident and collinear gamma rays in a method according to an aspect of the invention; and Figure 3 diagrammatically illustrates components of an ore processing plant which can be used to implement a method according to an aspect of the invention.
4b SPECIFIC DESCRIPTION WITH REFERENCE TO THE DRAWINGS
In the first aspect of the invention as summarised above, bremsstrahlung is produced by means of a particle accelerator of sufficient energy to excite GDR in carbon nuclei which may be present in particles undergoing analysis.
It is noted that GDR is a fundamental mode of excitation of all nuclei, including carbon nuclei, characterised by its considerable intensity, width and median energy. The full, continuous bremsstrahlung can be used with an energy end point exceeding the upper end of the energy band window which encompasses the characteristic GDR value for carbon, i.e. about 22 MeV.
The bremsstrahlung may be monochromatised, typically by collimation of particular anglers of emission, to have an energy bandwidth sufficient to cover the characteristic GDR width at a selected median value.
Particles, typically kimberlite particles, which are undergoing analysis for the presence of diamond, are individually irradiated with the bremsstrahlung. In a case where a mass of diamondiferous kimberlite particles is to be analysed with a view to separating from barren particles those particles which are diamond-containing particles, the particles may for instance be transported in single file or in a monolayer through an irradiation station at which they are individually irradiated. This may, for instance, be on a conveyor such as a conveyor belt, or during free fall of the particles from a discharge point.
The bremsstrahlung is absorbed to a far greater extent by carbon, i.e.
diamond, in the particles at the characteristic photon energy than it is by host rock in which the diamonds are embedded. From a derived, differential absorption image it is then possible to detect the presence of diamond in the particle. Imaging may be achieved by simple linear geometry detection arrays or by more complex tomographic systems. In either event, standard image enhancement techniques can be used to improve the contrast between diamond and the associated rock in the image. The generally low concentration of carbon, homogenously distributed in the associated rock forms a faint outline background on which the higher density, higher concentration of carbon in diamond is superimposed.
In cases where the above analysis indicates the presence of diamond in a particle, that particle is separated from other, barren particles, typically with the use of conventional sorting equipment. For instance, where the particles are transported and analysed on a conveyor belt, and are then projected from an end of the belt to fall freely under gravity, selected particles may be deflected out of the falling stream by means of suitable air blast ejectors operating under the control of a computer which performs the analysis.
It will however be understood that any suitable form of sorting apparatus can be used to separate particles for which there is a positive identification of diamond presence from other, barren particles for which there is no such identification.
In the preferred, second aspect of the invention as summarised above, the particles undergoing analysis are again irradiated with gamma ray bremsstrahlung at a predetermined energy. The incident photons activate the carbon content of relevant particles through the nuclear reaction:
12C(y,n)-- 11C with Q = - 18.7215 MeV
11C-> R++(3- with Q = + 1.982 MeV
,c(11C) = 20 min The twenty minute half-life for the decay of 11C makes the reaction distinctive and represents a convenient period of time for the application of subsequent interrogative procedures, as described below.
When the positron comes to rest it promptly annihilates with an electron, as follows:
+R =Y+
The two gamma rays are coincident and collinear and each has a distinctive energy of 0.511 MeV, making them readily detectable. Their unique signature (back-to-back, time coincident and energy resolved) can be used to locate and image the source of the collinear pair of photons each of 0.511 MeV in energy, as described further below.
The sensitivity of the method just described can be enhanced by careful selection of the incident photon energy. With a Q value of -18.7215 MeV the threshold energy level for the reaction to occur is +18.7215 MeV. However, as stated above, the characteristic GDR value for carbon, i.e. diamond, is about 22 MeV. It is therefore considered that the incident photon energy should optimally extend to a value beyond 30 MeV. This can be provided either in the form of continuous bremsstrahlung with its end-point in this range or by an energy window of photons with a width sufficiently broad to embrace the full GDR spectrum and a suitable median energy. By carefully selecting the incident photon energy level in this way, it is possible to reduce the amount of radiation damage suffered by the particles undergoing analysis without, however, reducing the detectability of the response.
As in the method according to the first aspect of the invention, particles which are positively identified as having diamond inclusions are separated from the other, barren particles for which there is no positive identification. The distinctiveness of the "C half-life and two coincident and collinear gamma ray photons each with energy 0,511 MeV, together with the imaging of the source points of this radiation, makes the method suitable for distinguishing and separating not only diamonds which are fully or partially embedded inclusions in host particles, but also free diamonds as discrete particles whether in isolation or mixed with other particles, eg in a container, in a gravel concentrate or during conveyance on a conveyor belt or the like.
An important feature of the second method described above arises from the high penetrative power of the incident photons at the selected energy which is consistent with the generation of a GDR effect in diamond and also the high penetrative power of the emitted gamma ray photons.
This is important both from the point of view of how large each particle can sensibly be and how uniformly a particle can be irradiated with the photon flux. Referring to the incident photon flux, it can for instance be shown theoretically that for a typical kimberlite having a density of 2.8gcm-3 , only 50% of an initial 30 MeV photon flux is attenuated by passage through 13cm of the kimberlite sample and for sample thicknesses of 10cm and 44cm, the corresponding attenuation values for the same initial photon flux are 22% and 90% respectively. Thus, to take 10cm kimberlite particles as an example, adequate activation of any diamond inclusion can readily be achieved at the photon energy of 30 MeV. It is in any event possible to apply appropriate corrections to take account of the expected attenuation.
Thus it will be understood that it is possible with the method of the invention to analyse large particles and that the initial ore crushing steps can be tailored accordingly. It will also be understood that although the term "particle" is used throughout this specification, the invention is not limited to the analysis of mineral fragments which are small in size.
Referring to the penetrative power and hence detectability of the characteristic, emitted gamma ray photons, it can be shown theoretically that for a diamond at the centre of a spherical kimberlite particle of 10cm diameter, the 0.511 MeV gamma ray photons which are emitted by the diamond inclusion, and which reach the surface of the particle, are attenuated by 70%, leaving an adequate 30% of the original flux for detection. Nevertheless, given that the particles undergoing analysis will be irregular in shape and that any diamond inclusions will rarely be at the centre, it is believed that it may be advantageous to surround the particles with detectors, thereby to improve the likelihood of detection of the diamond.
In a practical apparatus, the particles may be irradiated with the incident photon flux at an upstream position on a conveyor belt, with gamma ray detection then taking place at a downstream position on the belt selected to take account of the characteristic 20 minute half-life. The detectors may be used in singles mode, coincidence mode or a combination thereof.
As a further feature of the method of the second aspect of the invention it is possible to determine not only whether a particle has a diamond inclusion, but also the location and size of the inclusion in the particle. From the absolute intensity of the gamma ray emission it is possible to determine the size of the diamond inclusion. For determination of the location of the diamond in the particle, it would be possible to implement image reconstruction algorithms.
It would for instance be possible to use two gamma ray detectors and to rotate the particle between them. Alternatively it would be possible to use a PET
camera system with a large array of stationary detectors or a smaller array of movable detectors in order to create a three-dimensional image with adequate spatial resolution for accurate determination of the location of the inclusion. Modern detectors with sufficient spatial resolution and sophisticated software are available and the principle has been experimentally verified. More is said below about a currently preferred detector arrangement.
It is recognised that photon interaction with kimberlite could create signal interference. 53Fe, 52Mn and "'Sr have half-lives comparable to 11C but are found in such low concentrations in Kimberlite as to have no significant effect on the detection of 11C. Interference from 44K would be a concern except that the photon energy is 0.4 MeV and suitable energy selection of the 0.511 MeV
photons would eliminate this interference.
The most common element in a kimberlite sample is oxygen, the half-life of which, as produced by the relevant nuclear reaction, is however only 2.03 minutes. Thus the problem which the interference could cause can be sufficiently mitigated by only performing the carbon detection steps after several 160 half-lives, for example after ten minutes or so, after the oxygen activation has ceased. The remaining positron decay will be dominated by the twenty minute half-life and accordingly distinctive of carbon.
The radioactivity of the irradiated kimberlite after it is discarded can be shown to be small. The majority of the elements that are activated have half-lives from a few seconds to a few hours. After one day the radiation levels would be significantly reduced. As for irradiated diamonds containing large inclusions, it has been shown experimentally that by far the dominant source of radiation is "C which decays away after a few hours.
From the above it will be understood that the identification of carbon using the method proposed by this aspect of the invention relies on the detection of two coincident and collinear photons emitted from the vicinity of carbon atoms as a result of the sequence of reactions described earlier.
Both diamond and non-diamond sources of carbon will lead to the same signature of coincident and collinear photons. The non-diamond forms of carbon in kimberlite are in finer particulates or are essentially homogeneously distributed, as compared to the diamond form of carbon in the size range of interest. The typical concentration of non-diamond carbon is about 0,2%. The intensity of the carbon signal alone is insufficient to recognise the potential occurrence of a diamond particle for host kimberlite volumes larger than about 500 times the volume of the diamond.
This problem can be addressed by the quasi-imaging of the source geometry of the carbon signals, identifying essentially the density of the carbon in the source region. Equivalently the carbon signal originating from a diamond is not seen against the whole kimberlite volume but rather against a smaller volume, namely a minimum volume element which can be identified by the quasi-imaging process. This technique can accordingly improve the discrimination between the diamond and non-diamond forms of carbon.
This is based on the fact that for most types of kimberlite under consideration, the diamond form of carbon represents the strongest localised source of carbon signals. The quasi-imaging technique exploits the fact that the two photons are coincident and collinear, so that a PET type algorithm may be used to reconstruct the source distribution of the double photon events which take place. A suitable PET type algorithm is one which makes use of a two dimensional array of detectors with the source material moving relative thereto, typically an array of PET type detectors arranged along the length of and surrounding the conveyor system.
This is illustrated in the accompanying diagrammatic drawings. As shown in Figure 1, the kimberlite or other source material 10 is moved at constant velocity by a transport system, such as the illustrated conveyor belt 12, through two imaging devices 14 and 16. The first device 14 images the rough physical dimensions of the material particles. This could for instance be achieved by an array of photodiodes to produce a two dimensional "shadow "
of the material which, along with the associated time component, can be reconstructed by suitable software algorithms to create a three dimensional representation of the transported particles.
The second device 16, which is a quasi-imaging device as referred to above, works in a manner analogous to that of a PET device. The coincident and collinear- photons are detected by an array of position sensitive photon detectors 18 (Figure 2) which measure the position of the detected photon, the time at which such measurement took place and the photon energy.
The information so obtained by the detectors 18 can then be analysed by appropriate software which correctly assigns the detected photons into coincident pairs at given times relative to the instantaneous position of the source material. In effect the software algorithm freezes the motion of the source material and employs a ray tracing technique, based on the collinear back-to-back emission to reconstruct a density map of carbon signals from the source material. The eventual image reconstruction is reliant on the position sensitive nature of the photon detectors 18 as well as the identified photon pairs and their collinear nature.
For accurate image reconstruction good time resolution of the detectors is essential for correct identification of coincident pairs of photons. It has been established that the random to real coincident ratio can be neglected if detectors with nanosecond time resolutions are used.
Combining the reconstructed image with the physical image of the source material particle obtained by the device 14 enables a decision to be made as to whether the particle in question contains a localised concentration of carbon, i.e. a localised concentration of carbon which is significantly higher than the average carbon concentration in kimberlite particles that are barren of diamond, and which are accordingly indicative of diamond 22, or not.
Thereafter, as explained previously, the particulate source material enters a sorting device 20 (Figure 1) which separates the identified particles from other particles.
Figure 3 diagrammatically illustrates the components of a processing plant which can be used to implement the method just described. The numeral 30 indicates a crusher set to reduce the particle size to 10cm or less. A chute directs the crushed particles onto an endless conveyor belt 34 which transports the particles through a 22MeV irradiator 36 which irradiates the particles with gamma radiation as described above. The particles are deposited by the belt into a hopper 38 which retains the particles for at least a twenty minute period before depositing them on an endless conveyor belt 40.
The latter belt transports the particles through a detection station at which an array 42 of detectors 44 surrounds the belt, as described above. Downstream of the detection station, particles identified as potentially containing diamond are tagged by a tagging device 46, whereafter the tagged particles are removed from the general stream of particles by a mechanical picking device 48. Barren particles 50 are deposited onto a further conveyor which transports them to waste while selected particles 52 are if necessary crushed at crushing stations 54 and subjected to conventional dense medium separation in dense medium separation units 56 followed, possibly, by conventional X-ray sorting in an X-ray sorter 58 to yield a diamond-rich product 60.
It is envisaged that in an underground diamond mine the process described above, at least up to the sorting stage, could be carried out underground.
The barren rocks could then be disposed of underground without the necessity to transport them to the surface. Only the selected particles are raised to surface for further processing.
It will be understood that the above description and the accompanying drawing are illustrative of certain embodiments of the invention and that many modifications are possible within the scope of the invention.
In accordance with another aspect of the invention, there is provided an on-line particle sorting method including the steps of irradiating particles with photons is an energy band window encompassing a characteristic value of about 22MeV at which GDR (giant dipole resonance) is excited for the nuclear reaction of the photons with carbon, identifying particles as potentially diamond or diamond-containing particles according to whether the isotope "C, with a characteristic half-life of approximately twenty minutes, is produced by the photon/carbon nuclear reaction and whether coincident and collinear gamma ray photons at a distinctive energy level are emitted by the particles, and separating from other particles those particles which are identified as potentially diamond or diamond-containing particles.
In accordance with another aspect of the invention, there is provided an apparatus for detecting the presence of diamond in a particle, the apparatus including means for irradiating the particle with photons in an energy band window encompassing a characteristic value of about 22MeV at which the GDR (giant dipole resonance) is excited for the nuclear reaction of the photons with carbon, and identification means for identifying the particle as potentially a diamond or diamond-containing particle according to whether the isotope 11C, with a characteristic half-life of approximately twenty minutes, is produced by the photon/carbon nuclear reaction.
4a In accordance with another aspect of the invention, there is provided an on-line particle sorting apparatus including irradiation means for irradiating particles in an energy band window encompassing a characteristic value of about 22MeV at which GDR (giant dipole resonance) is excited for the nuclear reaction of the photons with carbon, identification means for identifying particles as potentially diamond or diamond-containing particles according to whether the isotope 11C, with a characteristic half-life of approximately twenty minutes, is produced by the photon/carbon nuclear reaction and whether coincident and collinear gamma ray photons at a distinctive energy level are emitted by the particles, and means for separating from other particles those particles which are identified as potentially diamond or diamond-containing particles.
Other features of the invention will appear from the following description and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Aspects of the invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:
Figure 1 diagrammatically illustrates an on-line sorting method according to an aspect of the invention;
Figure 2 diagrammatically illustrates the detection of coincident and collinear gamma rays in a method according to an aspect of the invention; and Figure 3 diagrammatically illustrates components of an ore processing plant which can be used to implement a method according to an aspect of the invention.
4b SPECIFIC DESCRIPTION WITH REFERENCE TO THE DRAWINGS
In the first aspect of the invention as summarised above, bremsstrahlung is produced by means of a particle accelerator of sufficient energy to excite GDR in carbon nuclei which may be present in particles undergoing analysis.
It is noted that GDR is a fundamental mode of excitation of all nuclei, including carbon nuclei, characterised by its considerable intensity, width and median energy. The full, continuous bremsstrahlung can be used with an energy end point exceeding the upper end of the energy band window which encompasses the characteristic GDR value for carbon, i.e. about 22 MeV.
The bremsstrahlung may be monochromatised, typically by collimation of particular anglers of emission, to have an energy bandwidth sufficient to cover the characteristic GDR width at a selected median value.
Particles, typically kimberlite particles, which are undergoing analysis for the presence of diamond, are individually irradiated with the bremsstrahlung. In a case where a mass of diamondiferous kimberlite particles is to be analysed with a view to separating from barren particles those particles which are diamond-containing particles, the particles may for instance be transported in single file or in a monolayer through an irradiation station at which they are individually irradiated. This may, for instance, be on a conveyor such as a conveyor belt, or during free fall of the particles from a discharge point.
The bremsstrahlung is absorbed to a far greater extent by carbon, i.e.
diamond, in the particles at the characteristic photon energy than it is by host rock in which the diamonds are embedded. From a derived, differential absorption image it is then possible to detect the presence of diamond in the particle. Imaging may be achieved by simple linear geometry detection arrays or by more complex tomographic systems. In either event, standard image enhancement techniques can be used to improve the contrast between diamond and the associated rock in the image. The generally low concentration of carbon, homogenously distributed in the associated rock forms a faint outline background on which the higher density, higher concentration of carbon in diamond is superimposed.
In cases where the above analysis indicates the presence of diamond in a particle, that particle is separated from other, barren particles, typically with the use of conventional sorting equipment. For instance, where the particles are transported and analysed on a conveyor belt, and are then projected from an end of the belt to fall freely under gravity, selected particles may be deflected out of the falling stream by means of suitable air blast ejectors operating under the control of a computer which performs the analysis.
It will however be understood that any suitable form of sorting apparatus can be used to separate particles for which there is a positive identification of diamond presence from other, barren particles for which there is no such identification.
In the preferred, second aspect of the invention as summarised above, the particles undergoing analysis are again irradiated with gamma ray bremsstrahlung at a predetermined energy. The incident photons activate the carbon content of relevant particles through the nuclear reaction:
12C(y,n)-- 11C with Q = - 18.7215 MeV
11C-> R++(3- with Q = + 1.982 MeV
,c(11C) = 20 min The twenty minute half-life for the decay of 11C makes the reaction distinctive and represents a convenient period of time for the application of subsequent interrogative procedures, as described below.
When the positron comes to rest it promptly annihilates with an electron, as follows:
+R =Y+
The two gamma rays are coincident and collinear and each has a distinctive energy of 0.511 MeV, making them readily detectable. Their unique signature (back-to-back, time coincident and energy resolved) can be used to locate and image the source of the collinear pair of photons each of 0.511 MeV in energy, as described further below.
The sensitivity of the method just described can be enhanced by careful selection of the incident photon energy. With a Q value of -18.7215 MeV the threshold energy level for the reaction to occur is +18.7215 MeV. However, as stated above, the characteristic GDR value for carbon, i.e. diamond, is about 22 MeV. It is therefore considered that the incident photon energy should optimally extend to a value beyond 30 MeV. This can be provided either in the form of continuous bremsstrahlung with its end-point in this range or by an energy window of photons with a width sufficiently broad to embrace the full GDR spectrum and a suitable median energy. By carefully selecting the incident photon energy level in this way, it is possible to reduce the amount of radiation damage suffered by the particles undergoing analysis without, however, reducing the detectability of the response.
As in the method according to the first aspect of the invention, particles which are positively identified as having diamond inclusions are separated from the other, barren particles for which there is no positive identification. The distinctiveness of the "C half-life and two coincident and collinear gamma ray photons each with energy 0,511 MeV, together with the imaging of the source points of this radiation, makes the method suitable for distinguishing and separating not only diamonds which are fully or partially embedded inclusions in host particles, but also free diamonds as discrete particles whether in isolation or mixed with other particles, eg in a container, in a gravel concentrate or during conveyance on a conveyor belt or the like.
An important feature of the second method described above arises from the high penetrative power of the incident photons at the selected energy which is consistent with the generation of a GDR effect in diamond and also the high penetrative power of the emitted gamma ray photons.
This is important both from the point of view of how large each particle can sensibly be and how uniformly a particle can be irradiated with the photon flux. Referring to the incident photon flux, it can for instance be shown theoretically that for a typical kimberlite having a density of 2.8gcm-3 , only 50% of an initial 30 MeV photon flux is attenuated by passage through 13cm of the kimberlite sample and for sample thicknesses of 10cm and 44cm, the corresponding attenuation values for the same initial photon flux are 22% and 90% respectively. Thus, to take 10cm kimberlite particles as an example, adequate activation of any diamond inclusion can readily be achieved at the photon energy of 30 MeV. It is in any event possible to apply appropriate corrections to take account of the expected attenuation.
Thus it will be understood that it is possible with the method of the invention to analyse large particles and that the initial ore crushing steps can be tailored accordingly. It will also be understood that although the term "particle" is used throughout this specification, the invention is not limited to the analysis of mineral fragments which are small in size.
Referring to the penetrative power and hence detectability of the characteristic, emitted gamma ray photons, it can be shown theoretically that for a diamond at the centre of a spherical kimberlite particle of 10cm diameter, the 0.511 MeV gamma ray photons which are emitted by the diamond inclusion, and which reach the surface of the particle, are attenuated by 70%, leaving an adequate 30% of the original flux for detection. Nevertheless, given that the particles undergoing analysis will be irregular in shape and that any diamond inclusions will rarely be at the centre, it is believed that it may be advantageous to surround the particles with detectors, thereby to improve the likelihood of detection of the diamond.
In a practical apparatus, the particles may be irradiated with the incident photon flux at an upstream position on a conveyor belt, with gamma ray detection then taking place at a downstream position on the belt selected to take account of the characteristic 20 minute half-life. The detectors may be used in singles mode, coincidence mode or a combination thereof.
As a further feature of the method of the second aspect of the invention it is possible to determine not only whether a particle has a diamond inclusion, but also the location and size of the inclusion in the particle. From the absolute intensity of the gamma ray emission it is possible to determine the size of the diamond inclusion. For determination of the location of the diamond in the particle, it would be possible to implement image reconstruction algorithms.
It would for instance be possible to use two gamma ray detectors and to rotate the particle between them. Alternatively it would be possible to use a PET
camera system with a large array of stationary detectors or a smaller array of movable detectors in order to create a three-dimensional image with adequate spatial resolution for accurate determination of the location of the inclusion. Modern detectors with sufficient spatial resolution and sophisticated software are available and the principle has been experimentally verified. More is said below about a currently preferred detector arrangement.
It is recognised that photon interaction with kimberlite could create signal interference. 53Fe, 52Mn and "'Sr have half-lives comparable to 11C but are found in such low concentrations in Kimberlite as to have no significant effect on the detection of 11C. Interference from 44K would be a concern except that the photon energy is 0.4 MeV and suitable energy selection of the 0.511 MeV
photons would eliminate this interference.
The most common element in a kimberlite sample is oxygen, the half-life of which, as produced by the relevant nuclear reaction, is however only 2.03 minutes. Thus the problem which the interference could cause can be sufficiently mitigated by only performing the carbon detection steps after several 160 half-lives, for example after ten minutes or so, after the oxygen activation has ceased. The remaining positron decay will be dominated by the twenty minute half-life and accordingly distinctive of carbon.
The radioactivity of the irradiated kimberlite after it is discarded can be shown to be small. The majority of the elements that are activated have half-lives from a few seconds to a few hours. After one day the radiation levels would be significantly reduced. As for irradiated diamonds containing large inclusions, it has been shown experimentally that by far the dominant source of radiation is "C which decays away after a few hours.
From the above it will be understood that the identification of carbon using the method proposed by this aspect of the invention relies on the detection of two coincident and collinear photons emitted from the vicinity of carbon atoms as a result of the sequence of reactions described earlier.
Both diamond and non-diamond sources of carbon will lead to the same signature of coincident and collinear photons. The non-diamond forms of carbon in kimberlite are in finer particulates or are essentially homogeneously distributed, as compared to the diamond form of carbon in the size range of interest. The typical concentration of non-diamond carbon is about 0,2%. The intensity of the carbon signal alone is insufficient to recognise the potential occurrence of a diamond particle for host kimberlite volumes larger than about 500 times the volume of the diamond.
This problem can be addressed by the quasi-imaging of the source geometry of the carbon signals, identifying essentially the density of the carbon in the source region. Equivalently the carbon signal originating from a diamond is not seen against the whole kimberlite volume but rather against a smaller volume, namely a minimum volume element which can be identified by the quasi-imaging process. This technique can accordingly improve the discrimination between the diamond and non-diamond forms of carbon.
This is based on the fact that for most types of kimberlite under consideration, the diamond form of carbon represents the strongest localised source of carbon signals. The quasi-imaging technique exploits the fact that the two photons are coincident and collinear, so that a PET type algorithm may be used to reconstruct the source distribution of the double photon events which take place. A suitable PET type algorithm is one which makes use of a two dimensional array of detectors with the source material moving relative thereto, typically an array of PET type detectors arranged along the length of and surrounding the conveyor system.
This is illustrated in the accompanying diagrammatic drawings. As shown in Figure 1, the kimberlite or other source material 10 is moved at constant velocity by a transport system, such as the illustrated conveyor belt 12, through two imaging devices 14 and 16. The first device 14 images the rough physical dimensions of the material particles. This could for instance be achieved by an array of photodiodes to produce a two dimensional "shadow "
of the material which, along with the associated time component, can be reconstructed by suitable software algorithms to create a three dimensional representation of the transported particles.
The second device 16, which is a quasi-imaging device as referred to above, works in a manner analogous to that of a PET device. The coincident and collinear- photons are detected by an array of position sensitive photon detectors 18 (Figure 2) which measure the position of the detected photon, the time at which such measurement took place and the photon energy.
The information so obtained by the detectors 18 can then be analysed by appropriate software which correctly assigns the detected photons into coincident pairs at given times relative to the instantaneous position of the source material. In effect the software algorithm freezes the motion of the source material and employs a ray tracing technique, based on the collinear back-to-back emission to reconstruct a density map of carbon signals from the source material. The eventual image reconstruction is reliant on the position sensitive nature of the photon detectors 18 as well as the identified photon pairs and their collinear nature.
For accurate image reconstruction good time resolution of the detectors is essential for correct identification of coincident pairs of photons. It has been established that the random to real coincident ratio can be neglected if detectors with nanosecond time resolutions are used.
Combining the reconstructed image with the physical image of the source material particle obtained by the device 14 enables a decision to be made as to whether the particle in question contains a localised concentration of carbon, i.e. a localised concentration of carbon which is significantly higher than the average carbon concentration in kimberlite particles that are barren of diamond, and which are accordingly indicative of diamond 22, or not.
Thereafter, as explained previously, the particulate source material enters a sorting device 20 (Figure 1) which separates the identified particles from other particles.
Figure 3 diagrammatically illustrates the components of a processing plant which can be used to implement the method just described. The numeral 30 indicates a crusher set to reduce the particle size to 10cm or less. A chute directs the crushed particles onto an endless conveyor belt 34 which transports the particles through a 22MeV irradiator 36 which irradiates the particles with gamma radiation as described above. The particles are deposited by the belt into a hopper 38 which retains the particles for at least a twenty minute period before depositing them on an endless conveyor belt 40.
The latter belt transports the particles through a detection station at which an array 42 of detectors 44 surrounds the belt, as described above. Downstream of the detection station, particles identified as potentially containing diamond are tagged by a tagging device 46, whereafter the tagged particles are removed from the general stream of particles by a mechanical picking device 48. Barren particles 50 are deposited onto a further conveyor which transports them to waste while selected particles 52 are if necessary crushed at crushing stations 54 and subjected to conventional dense medium separation in dense medium separation units 56 followed, possibly, by conventional X-ray sorting in an X-ray sorter 58 to yield a diamond-rich product 60.
It is envisaged that in an underground diamond mine the process described above, at least up to the sorting stage, could be carried out underground.
The barren rocks could then be disposed of underground without the necessity to transport them to the surface. Only the selected particles are raised to surface for further processing.
It will be understood that the above description and the accompanying drawing are illustrative of certain embodiments of the invention and that many modifications are possible within the scope of the invention.
Claims (14)
1. A method of detecting the presence of diamond in a particle, wherein the particle is irradiated with photons in an energy band window encompassing a characteristic value of about 22MeV at which the GDR (giant dipole resonance) is excited for the nuclear reaction of the photons with carbon, and identifying the particle as potentially a diamond or diamond-containing particle according to whether the isotope "C, with a characteristic half-life of approximately twenty minutes, is produced by the photon/carbon nuclear reaction.
2. A method according to claim 1 wherein the particle is identified as potentially a diamond or diamond containing particle according to whether or not coincident and collinear gamma ray photons at a distinctive energy level are emitted by the particle.
3. A method according to claim 2 wherein the distinctive energy level is 0.511 MeV.
4. A method according to either one of claims 2 or 3 including the step of analysing detected coincident and collinear gamma ray photons to provide an indication of the relative position of a concentrated carbon inclusion, potentially a diamond, in a particle which is host to such inclusion.
5. An on-line particle sorting method including the steps of irradiating particles with photons in an energy band window encompassing a characteristic value of about 22MeV at which GDR (giant dipole resonance) is excited for the nuclear reaction of the photons with carbon, identifying particles as potentially diamond or diamond-containing particles according to whether the isotope 11C, with a characteristic half-life of approximately twenty minutes, is produced by the photon/carbon nuclear reaction and whether coincident and collinear gamma ray photons at a distinctive energy level are emitted by the particles, and separating from other particles those particles which are identified as potentially diamond or diamond-containing particles.
6. An on-line particle sorting method according to claim 5 wherein, after irradiation, the particles are retained for at least twenty minutes before further analysis steps are carried out on the particles.
7. An on-line particle sorting method according to claim 5 or claim 6 including the step of identifying the particle as potentially a diamond or diamond-containing particle according to whether coincident and collinear gamma ray photons at an energy level of 0.511 MeV are emitted by the particle.
8. An apparatus for detecting the presence of diamond in a particle, the apparatus including means for irradiating the particle with photons in an energy band window encompassing a characteristic value of about 22MeV at which the GDR
(giant dipole resonance) is excited for the nuclear reaction of the photons with carbon, and identification means for identifying the particle as potentially a diamond or diamond-containing particle according to whether the isotope 11C, with a characteristic half-life of approximately twenty minutes, is produced by the photon/carbon nuclear reaction.
(giant dipole resonance) is excited for the nuclear reaction of the photons with carbon, and identification means for identifying the particle as potentially a diamond or diamond-containing particle according to whether the isotope 11C, with a characteristic half-life of approximately twenty minutes, is produced by the photon/carbon nuclear reaction.
9. An apparatus according to claim 8 including means for determining whether coincident and collinear gamma ray photons at a distinctive energy level are emitted by the particles.
10. An apparatus according to claim 9 including means for determining whether coincident and collinear gamma ray photons at an energy level of 0.511 MeV
are emitted by the particle.
are emitted by the particle.
11. An apparatus according to claim 10 including means for analysing detected coincident and collinear gamma ray photons to provide an indication of the relative position of a concentrated carbon inclusion, potentially a diamond, in a particle which is host to such inclusion.
12. An on-line particle sorting apparatus including irradiation means for irradiating particles in an energy band window encompassing a characteristic value of about 22MeV at which GDR (giant dipole resonance) is excited for the nuclear reaction of the photons with carbon, identification means for identifying particles as potentially diamond or diamond-containing particles according to whether the isotope "C, with a characteristic half-life of approximately twenty minutes, is produced by the photon/carbon nuclear reaction and whether coincident and collinear gamma ray photons at a distinctive energy level are emitted by the particles, and means for separating from other particles those particles which are identified as potentially diamond or diamond-containing particles.
13. An on-line particle sorting apparatus according to claim 12 including temporary storage means for retaining the particles for a period of at least twenty minutes after irradiation and before operation of the identification means.
14. An on-line particle sorting apparatus according to claim 12 wherein the apparatus includes a storage means in the form of a hopper for holding the particles after irradiation and for releasing the particles to the identification means after it has held them for at least twenty minutes.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA2004/2010 | 2004-03-12 | ||
| ZA200402010 | 2004-03-12 | ||
| PCT/IB2005/000643 WO2005088283A1 (en) | 2004-03-12 | 2005-03-14 | Detection of diamonds |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2559516A1 CA2559516A1 (en) | 2005-09-22 |
| CA2559516C true CA2559516C (en) | 2012-07-10 |
Family
ID=34962210
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2559516A Active CA2559516C (en) | 2004-03-12 | 2005-03-14 | Detection of diamonds |
Country Status (7)
| Country | Link |
|---|---|
| CN (1) | CN1942759B (en) |
| AP (1) | AP1986A (en) |
| AU (1) | AU2005220403B2 (en) |
| CA (1) | CA2559516C (en) |
| RU (1) | RU2334974C2 (en) |
| WO (1) | WO2005088283A1 (en) |
| ZA (1) | ZA200608025B (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AP2011005890A0 (en) * | 2009-02-23 | 2011-10-31 | Tech Resources Pty Ltd | Detecting a mineral within a material. |
| GB2481283B (en) | 2010-06-03 | 2013-07-17 | Element Six Ltd | A method of increasing the toughness and/or wear resistance of diamond tool pieces and diamond tool pieces fabricated by said method |
| US20130186992A1 (en) * | 2010-08-04 | 2013-07-25 | Technological Resources Pty. Limited | Sorting mined material |
| RU2470714C1 (en) * | 2011-07-21 | 2012-12-27 | Общество с ограниченной ответственностью "Лаборатория рентгенодиагностических систем" | Method of separating diamonds |
| GB2504052B (en) * | 2012-03-16 | 2017-05-10 | De Beers Uk Ltd | Sorting aggregate material |
| RU2517148C1 (en) * | 2012-12-28 | 2014-05-27 | Евгений Матвеевич Лукьянченко | Method of useful material particles separation and device to this end |
| RU2521723C1 (en) * | 2013-03-01 | 2014-07-10 | Общество с ограниченной ответственностью "Нейтронные технологии" | Method and apparatus for detecting diamonds in kimberlite |
| RU2612734C2 (en) * | 2015-08-18 | 2017-03-13 | Общество с ограниченной ответственностью "Диамант" | Installation for dry enrichment of kimberlite ore by method of labelled neutrons |
| CN105499156B (en) * | 2015-12-02 | 2019-03-01 | 虞雅仙 | A kind of water drilling inspection method |
| RU2670677C9 (en) * | 2017-02-07 | 2019-09-13 | Акционерная компания "АЛРОСА" (публичное акционерное общество) "АК "АЛРОСА" (ПАО)) | Device for diamond separation |
| CN111433635B (en) * | 2017-10-19 | 2023-09-15 | 约翰内斯堡大学 | gamma ray tomography |
| WO2020121214A1 (en) * | 2018-12-11 | 2020-06-18 | University Of Johannesburg | Detector arrangement, detection system and method of processing data from a detector arrangement for high throughput data handling |
| WO2020152618A1 (en) * | 2019-01-23 | 2020-07-30 | University Of Johannesburg | Detector arrangement, detection system and method of positioning a detector arrangement to reduce imaging artefacts |
| NL2026338B1 (en) * | 2020-08-25 | 2022-04-29 | Univ Johannesburg | Material analysis method and system |
| CN112024451B (en) * | 2020-08-28 | 2021-08-31 | 北京科技大学 | Ore sorting decision-making method based on analysis of operation characteristic curve of subject |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0059033A1 (en) * | 1981-02-24 | 1982-09-01 | Sphere Investments Limited | Ore sorting |
| US4428902A (en) * | 1981-05-13 | 1984-01-31 | Murray Kenneth M | Coal analysis system |
| US4756866A (en) * | 1985-10-09 | 1988-07-12 | Alvarez Luis W | Nitrogen detection |
| GB2219081B (en) * | 1988-05-06 | 1992-12-02 | Gersan Ets | Identifying specific objects or zones |
| GB2219394B (en) * | 1988-05-06 | 1992-09-16 | Gersan Ets | Sensing a narrow frequency band of radiation and examining objects or zones |
| US5334652A (en) * | 1991-06-18 | 1994-08-02 | Exxon Chemical Patents, Inc. | Polyester-based coating compositions having high pigment-to-binder ratios |
| CA2138503C (en) * | 1993-12-22 | 2004-10-12 | Ulf Anders Staffan Tapper | Method and apparatus for the classification of particulate matter |
| CA2139537C (en) * | 1994-01-07 | 2007-04-24 | Ulf Anders Staffan Tapper | Method and apparatus for the classification of matter |
| CN1363836A (en) * | 2001-08-18 | 2002-08-14 | 李晓蔚 | Method for judging natural product |
-
2005
- 2005-03-14 CN CN2005800116079A patent/CN1942759B/en not_active Expired - Fee Related
- 2005-03-14 ZA ZA200608025A patent/ZA200608025B/en unknown
- 2005-03-14 RU RU2006135960/28A patent/RU2334974C2/en active
- 2005-03-14 WO PCT/IB2005/000643 patent/WO2005088283A1/en active Application Filing
- 2005-03-14 AU AU2005220403A patent/AU2005220403B2/en active Active
- 2005-03-14 CA CA2559516A patent/CA2559516C/en active Active
-
2006
- 2006-09-29 AP AP2006003753A patent/AP1986A/en active
Also Published As
| Publication number | Publication date |
|---|---|
| CN1942759A (en) | 2007-04-04 |
| AP2006003753A0 (en) | 2006-10-31 |
| RU2334974C2 (en) | 2008-09-27 |
| WO2005088283A1 (en) | 2005-09-22 |
| CA2559516A1 (en) | 2005-09-22 |
| AU2005220403B2 (en) | 2010-12-09 |
| AU2005220403A1 (en) | 2005-09-22 |
| CN1942759B (en) | 2011-01-12 |
| RU2006135960A (en) | 2008-04-20 |
| ZA200608025B (en) | 2008-06-25 |
| AP1986A (en) | 2009-04-01 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA2559516C (en) | Detection of diamonds | |
| KR100261529B1 (en) | Apparatus and method for detecting contraband using fast neutron activation | |
| US7483509B2 (en) | Detecting special nuclear materials in suspect containers using high-energy gamma rays emitted by fission products | |
| CA2139537C (en) | Method and apparatus for the classification of matter | |
| CN1779451B (en) | Back scattering safety inspector for liquid by radioactive resource | |
| CN105074440A (en) | Primary and secondary scanning in muon tomography inspection | |
| AU6359090A (en) | Multi-sensor explosive detection system | |
| JP6896062B2 (en) | Inspection equipment and inspection method | |
| RU2521723C1 (en) | Method and apparatus for detecting diamonds in kimberlite | |
| JPS6168577A (en) | Method of continuously selecting radioactive substance from non-radioactive substance | |
| US8642969B2 (en) | Sealed tube neutron generator equipped with alpha particle detectors and associated particle measurement system which uses the generator | |
| EP1269166A2 (en) | Detection of fissile material | |
| CA2138503C (en) | Method and apparatus for the classification of particulate matter | |
| EP0064810A1 (en) | Sorting particulate material | |
| Jakubek et al. | Imaging with secondary radiation in hadron therapy beams with the 3D sensitive voxel detector | |
| Parry | Neutron activation analysis | |
| US20090232277A1 (en) | System and method for inspection of items of interest in objects | |
| RU2003082C1 (en) | Method of identification of gold-bearing rocks | |
| RU2813286C2 (en) | Detection device, detection system and method for positioning detection device for reducing image artifacts | |
| WO2020152618A1 (en) | Detector arrangement, detection system and method of positioning a detector arrangement to reduce imaging artefacts | |
| Sebele | Detection of diamonds using the tagged neutron method | |
| US20230294136A1 (en) | Method and system for sorting of diamonds | |
| Tumer et al. | Three-dimensional container and cargo inspection system | |
| Furlan et al. | Muons scanner to detect radioactive source hidden in scrap metal containers: Mu-steel EU project | |
| Garola | Muon tomography effectiveness in detecting orphan sources in scrap metal |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request |