GB2107861A - Particulate sorting apparatus - Google Patents

Particulate sorting apparatus Download PDF

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Publication number
GB2107861A
GB2107861A GB08230273A GB8230273A GB2107861A GB 2107861 A GB2107861 A GB 2107861A GB 08230273 A GB08230273 A GB 08230273A GB 8230273 A GB8230273 A GB 8230273A GB 2107861 A GB2107861 A GB 2107861A
Authority
GB
United Kingdom
Prior art keywords
mass
selective region
particles
stream
detector
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.)
Granted
Application number
GB08230273A
Other versions
GB2107861B (en
Inventor
Henry Joseph Coppens
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
De Beers Industrial Diamond Division Pty Ltd
Original Assignee
De Beers Industrial Diamond Division Pty Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by De Beers Industrial Diamond Division Pty Ltd filed Critical De Beers Industrial Diamond Division Pty Ltd
Publication of GB2107861A publication Critical patent/GB2107861A/en
Application granted granted Critical
Publication of GB2107861B publication Critical patent/GB2107861B/en
Expired legal-status Critical Current

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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
    • G01N23/223—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 irradiating the sample with X-rays or gamma-rays and by measuring X-ray fluorescence
    • 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
    • B07C5/342—Sorting according to other particular properties according to optical properties, e.g. colour
    • B07C5/3425—Sorting according to other particular properties according to optical properties, e.g. colour of granular material, e.g. ore particles, grain
    • B07C5/3427—Sorting according to other particular properties according to optical properties, e.g. colour of granular material, e.g. ore particles, grain by changing or intensifying the optical properties prior to scanning, e.g. by inducing fluorescence under UV or x-radiation, subjecting the material to a chemical reaction
    • 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
    • B07C5/36—Sorting apparatus characterised by the means used for distribution
    • B07C5/363—Sorting apparatus characterised by the means used for distribution by means of air
    • B07C5/365—Sorting apparatus characterised by the means used for distribution by means of air using a single separation means
    • B07C5/366—Sorting apparatus characterised by the means used for distribution by means of air using a single separation means during free fall of the articles
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2223/00—Investigating materials by wave or particle radiation
    • G01N2223/07—Investigating materials by wave or particle radiation secondary emission
    • G01N2223/076—X-ray fluorescence

Abstract

The invention provides apparatus for sorting particulate masses such as particulate diamondiferous ores. The apparatus has a source of X-ray radiation which exposes a selective region and through which a stream of the mass is arranged to pass. A photo detector device monitors luminescence produced by particles in the mass as a result of the radiation and controls a jet of air which separates selected particles having a predetermined luminescence characteristic from the other particles in the mass. The apparatus is characterized by a lens system 34 which concentrates the field of view D of the photodetector 30 on to and within the selective region. <IMAGE>

Description

SPECIFICATION Particulate sorting apparatus Background of the invention The invention relates to.apparatus for sorting particulate masses.
The invention relates more particularly to sorting apparatus which detects ore particles by using X-ray radiation and detecting luminescence caused by the radiation. Ore particles which luminesce when subjected to X-ray radiation include diamonds. Normally, in sorting apparatus of this kind, gravel containing diamonds is passed through a station where the gravel is exposed to X-ray radiation and a photo-detector is provided for monitoring luminescence and controlling the selection or rejection of diamonds by initiating a series of air jets.
Summary of the invention According to the invention there is provided apparatus for sorting particulate masses including a source of X-ray radiation arranged to expose a selective region, means to deliver a stream of the mass through the selective region, a photodetector device for monitoring luminescence produced by particles in the mass as a- result of the radiation and for controlling in response thereto a selecting device to separate selected particles having a predetermined luminescence characteristic from the other particles in the mass and optical focussing means arranged to concentrate the field of view of the photodetector on to and within the selective region.
The luminescence characteristic to which the photo-detector responds will generally be luminescence above a predetermined threshold value.
Preferably, the focussing means is arranged to concentrate the field of view on to a small part of the selective region. The small part can be conveniently chosen at the centre of the selective region where the luminescence tends to be greatest. However, as maximum luminescence can be somewhat time delayed with respect to exposure to radiation of some ore particles, the small part can be selected within the area but downstream of the centre of the selective area.
The focussing means is preferably a lens system having focal points on each of opposite sides thereof, the one focal point being in the path of the stream of particulate mass and the other being at the detecting surface of the photo detector.
The feed means may be any known in the art, for example a movable conveyor belt adapted to deliver a stream of the mass through the selective region. The stream of the mass may also be presented in monolayer form by being discharged from the edge of an inclined chute.
The selective device is typically a nozzle capable of issuing a stream of a fluid, generally air, to divert the selected particles from the stream of the mass.
Brief description of the drawing An apparatus according to the invention will now be described by way of example with reference to the accompanying drawing in which: Figure 1 shows part of the apparatus schematically; Figure 2 shows a sectional view of a photomultiplier detector device according to the prior art; and Figure 3 shows a sectional view of a photomultiplier detector device for use in the apparatus according to the invention.
Description of a preferred embodiment Referring to Figure 1 of the drawing, part of a generally conventional X-ray radiation or sorting apparatus is shown comprising a conveyor belt 10 supported by a drum 12. Gravel containing ore particles are conveyed by the belt 10 and travel in free trajectory towards collection bins 14 and 1 6.
An X-ray radiation source 1 8 is positioned to expose a selected area through which the ore particles travel and a photo-multiplier detector 20 is positioned to monitor luminescence occurring within the selected area. If the magnitude of luminescence detected is greater than a predetermined amount, the detector 20 produces a selection control signal for causing a jet of air to be directed out of a nozzle 22 to divert the ore particle into the bin 14. The air jet is arranged to be generated after a suitable time period, following detection of luminescence according to the speed of the particles, by control circuits (not shown). Such arrangements per se are known in the art.
In Figure 2 a prior art photo-multiplier detector has a detecting surface 30 and a collimator 32 through which light can pass. The detector surface 30 responds to any luminescence whose electronic output signal is represented graphically by line C in the area between A to B, which area represents the extent of the selected area exposed to radiation. The selection control signal is generated immediately the value of C exceeds the predetermined value. An ore particle can be detected at any point between A and B. The position of the particle is thus not precisely determined relative to nozzle 22 resulting in a real risk of inefficient separation.
In Figure 3, the collimator 32 is provided with a lens system 34 arranged to reduce the field of view of the photo detector 20 to a very small area D. In fact, the ore particles pass the collimator at the effective focal point of the detector 20. Thus, using the detector of Figure 3 the selection signal is generated only if the luminescence in the region of D is above the predetermined value. This means in effect that the position along the flight trajectory where the ore particle is detected represents a finite or precise relative position.
Because of this, the time period mentioned earlier by which the air jet is delayed can be arranged more precisely and effectively determined to divert only ore particles detected. Further, as the effective angle subtended (a) by the detector surface 30 is greater in Figure 3, more energy is available at the surface for detection than in Figure 2.
Some diamonds do not luminesce immediately they are exposed to X-ray radiation so it is not feasible to reduce the selected area A to B to overcome this problem. If the area A to B is made greater then diamonds which respond quickly to radiation are detected by the detector of Figure 2 soon after they enter the area A to B. If the air jet remains active for a sufficient time period to accommodate ore particles selected anywhere in the area A to B, then other than ore particles will tend to be diverted into the bin 14.
With the detector of Figure 3, ore particles at D will have been exposed for a sufficient period of time to luminesce above the predetermined amount whether they are the sort of diamonds which react immediately or after a time delay on receipt of radiation. In other words the lens system narrows or concentrates the field of view of the photo-detector and amplifies the signal it receives.
Further, as explained above by selecting only a small area for detection the sequenced operation of the air jets can be much more accurate because the position of detection is precisely known, that is at D, thus shorter duration of air jet can be used which enhances the overall sorting efficiency of the apparatus.
In the illustrated embodiment the particles are carried along on a conveyor belt. The conveyor belt can, of course; be replaced by other feed means such as a chute.

Claims (8)

Claims
1. Apparatus for sorting particulate masses include a source of X-radiation arranged to expose a selective region, means to deliver a stream of the mass through the selective region, a photo-detector device for monitoring luminescence produced by particles in the mass as a result of the radiation and for controlling in response thereto a selecting device to separate selected particles having a predetermined luminescence characteristic from the other particles in the mass and optical focussing means arranged to concentrate the field of view of the photo detector on to and within the selective region.
2. Apparatus according to claim 1 wherein the focussing means is arranged to concentrate the field of view on to a small part of the selective region.
3. Apparatus according to claim 2 wherein the small part is at the centre of the selective region.
4. Apparatus according to claim 2 wherein the small part is downstream of the centre of the selective region.
5. Apparatus according to any one of the preceding claims wherein the focussing means is a lens system having focal points on each of opposite sides thereof, the one focal point being in the path of the stream of particulate mass and the other being at the detecting surface of the photo-detector.
6. Apparatus according to any one of the preceding claims wherein the feed means comprising a movable conveyor belt is adapted to deliver a stream of the mass through the selective region.
7. Apparatus according to any one of the preceding claims wherein the selecting device is a nozzle capable of issuing a jet of fluid to divert the selected particles from the stream of the mass.
8. Apparatus according to claim 1 and substantially as herein described with reference to Figures 1 and 3 of the accompanying drawings.
GB08230273A 1981-10-23 1982-10-22 Particulate sorting apparatus Expired GB2107861B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
ZA817366 1981-10-23

Publications (2)

Publication Number Publication Date
GB2107861A true GB2107861A (en) 1983-05-05
GB2107861B GB2107861B (en) 1985-08-14

Family

ID=25575714

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08230273A Expired GB2107861B (en) 1981-10-23 1982-10-22 Particulate sorting apparatus

Country Status (2)

Country Link
AU (1) AU557022B2 (en)
GB (1) GB2107861B (en)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2527947A1 (en) * 1982-06-02 1983-12-09 Anglo Amer Corp South Africa METHOD AND APPARATUS FOR SORTING OBJECTS
US4693377A (en) * 1983-05-24 1987-09-15 The British Petroleum Company P.L.C. Diamond separation using raman scattering
GB2215041A (en) * 1988-01-29 1989-09-13 Argyle Diamond Sales Sorting and/or confirming the identity of gems
WO1993024833A1 (en) * 1992-06-03 1993-12-09 Gersan Establishment Detecting diamonds in a rock sample
GB2282882A (en) * 1992-06-03 1995-04-19 Gersan Ets Detecting diamonds in a rock sample
WO1996031770A1 (en) * 1995-04-07 1996-10-10 Technological Resources Pty. Limited A method and an apparatus for analysing a material
AU719072B2 (en) * 1995-04-07 2000-05-04 Technological Resources Pty Limited A method and an apparatus for analysing a material
AU747298B2 (en) * 1997-08-13 2002-05-16 De Beers Consolidated Mines Limited On-line diamond detection
GB2382135A (en) * 2001-11-20 2003-05-21 Spectral Fusion Technologies L X-ray apparatus for grading meat samples according to a predetermined meat to fat ratio
CN103913477A (en) * 2014-04-16 2014-07-09 国家黄金钻石制品质量监督检验中心 Method for identifying producing area of Mount Tai jade

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5206699A (en) 1988-05-06 1993-04-27 Gersan Establishment Sensing a narrow frequency band of radiation and gemstones

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2527947A1 (en) * 1982-06-02 1983-12-09 Anglo Amer Corp South Africa METHOD AND APPARATUS FOR SORTING OBJECTS
US4693377A (en) * 1983-05-24 1987-09-15 The British Petroleum Company P.L.C. Diamond separation using raman scattering
GB2215041A (en) * 1988-01-29 1989-09-13 Argyle Diamond Sales Sorting and/or confirming the identity of gems
AU666560B2 (en) * 1992-06-03 1996-02-15 De Beers Centenary AG Detecting diamonds in a rock sample
GB2282882A (en) * 1992-06-03 1995-04-19 Gersan Ets Detecting diamonds in a rock sample
GB2282882B (en) * 1992-06-03 1995-11-15 Gersan Ets Detecting diamonds in a rock sample
WO1993024833A1 (en) * 1992-06-03 1993-12-09 Gersan Establishment Detecting diamonds in a rock sample
US5603414A (en) * 1992-06-03 1997-02-18 Gersan Establishment Detecting diamonds in a rock sample
WO1996031770A1 (en) * 1995-04-07 1996-10-10 Technological Resources Pty. Limited A method and an apparatus for analysing a material
AU719072B2 (en) * 1995-04-07 2000-05-04 Technological Resources Pty Limited A method and an apparatus for analysing a material
US6122343A (en) * 1995-04-07 2000-09-19 Technological Resources Pty Limited Method and an apparatus for analyzing a material
AU747298B2 (en) * 1997-08-13 2002-05-16 De Beers Consolidated Mines Limited On-line diamond detection
GB2382135A (en) * 2001-11-20 2003-05-21 Spectral Fusion Technologies L X-ray apparatus for grading meat samples according to a predetermined meat to fat ratio
CN103913477A (en) * 2014-04-16 2014-07-09 国家黄金钻石制品质量监督检验中心 Method for identifying producing area of Mount Tai jade

Also Published As

Publication number Publication date
GB2107861B (en) 1985-08-14
AU557022B2 (en) 1986-12-04
AU8962282A (en) 1983-04-28

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19941022