GB2239519A - Method and apparatus for type IIB diamond sorting - Google Patents

Method and apparatus for type IIB diamond sorting Download PDF

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Publication number
GB2239519A
GB2239519A GB9026571A GB9026571A GB2239519A GB 2239519 A GB2239519 A GB 2239519A GB 9026571 A GB9026571 A GB 9026571A GB 9026571 A GB9026571 A GB 9026571A GB 2239519 A GB2239519 A GB 2239519A
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GB
United Kingdom
Prior art keywords
diamonds
type iib
ice
sorting
heated
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
GB9026571A
Other versions
GB2239519B (en
GB9026571D0 (en
Inventor
Edwin Harm Roos
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 GB9026571D0 publication Critical patent/GB9026571D0/en
Publication of GB2239519A publication Critical patent/GB2239519A/en
Application granted granted Critical
Publication of GB2239519B publication Critical patent/GB2239519B/en
Anticipated expiration legal-status Critical
Expired - Fee Related 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
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/389—Precious stones; Pearls
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
    • B07B13/00—Grading or sorting solid materials by dry methods, not otherwise provided for; Sorting articles otherwise than by indirectly controlled devices
    • B07B13/003—Separation of articles by differences in their geometrical form or by difference in their physical properties, e.g. elasticity, compressibility, hardness
    • 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

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Food Science & Technology (AREA)
  • Medicinal Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Sorting Of Articles (AREA)

Abstract

Diamonds which are to be sorted are subjected to a varying magnetic field or to electromagnetic radiation chosen to generate eddy currents in type IIB diamonds. The diamonds can then be sorted into a type IIB fraction and an "other diamond" fraction on the basis of the level to which they are heated up by the eddy currents. Sorting may be achieved by employing infra-red detectors and fluid blast ejectors, or by dropping the diamonds onto the surface of a body of ice which captures the hot type IIB diamonds.

Description

METHOD AND APPARATUS FOR IIB DIAMOND SORTING THIS invention relates to a sorting method and apparatus and, more particularly, a method of sorting type IIB diamonds from other diamond types.
It is known that type IIB diamonds are semi-conductors while all other diamond types have a very low electrical conductivity. The present invention proposes to make use of this characteristic of type IIB diamonds to sort them from other diamond types.
- According to the invention, there is provided a method of distinguishing type IIB diamonds from other diamonds, the method comprising the steps of subjecting diamonds to a varying magnetic field or to electromagnetic radiation chosen to induce eddy currents in the type IIB diamonds and identifying type IIB diamonds as those diamonds which are heated up to a level greater than a predetermined level.
Further according to the invention, there is provided a method of sorting type IIB diamonds from other types of diamonds, the method comprising the steps of subjecting the diamonds to a varying magnetic field or to electromagnetic radiation chosen to induce eddy currents in type IIB diamonds, and sorting type IIB diamonds from other diamonds on the basis of the level to which they are heated up.
Still further according to the invention, there is provided apparatus for distinguishing type IIB diamonds from other diamonds, the apparatus comprising means for subjecting the diamonds to a varying magnetic field or to electromagnetic radiation chosen to induce eddy currents in the type IIB diamonds, and means for identifying the type IIB diamonds as those diamonds which are heated up to a level greater than a predetermined level.
Apparatus may also be provided for sorting the type IIB diamonds so identified from the other diamonds.
The methods and apparatuses summarised above rely for their operation on the fact that type IIB diamonds are semiconductors while other diamond types have a relatively low electrical conductivity, and upon the fact that it is possible to induce eddy currents in an electrically conductive body by subjecting the body to a varying magnetic field or to electromagnetic radiation.
According to the present invention, diamonds which are to be sorted into type IIB diamonds on the one hand and other diamond types on the other hand, are subjected to an alternating magnetic field or to electromagnetic radiation.
In the latter case, the preferred radiation is high frequency radiation in the microwave or radio wave part of the electromagnetic spectrum.
The alternating magnetic field or radiation induces in the semi-conducting type IIB diamonds eddy currents which in turn heat up the type IIB diamonds by virtue of the electrical resistance of the diamonds. .Diamond types other than type IIB are not heated up to the same degree because of their far lower electrical conductivity. Thus the type IIB diamonds can be distinguished from the other diamond types by the level to which they are heated up.
The invention envisages that, having distinguished the type IIB diamonds from the other diamonds, it is possible to sort them automatically from the other diamonds by some or other sorting apparatus which is responsive to the detection of heat level in the various diamonds.
For instance, the sorting apparatus which is used could employ infra-red detectors which would produce an appropriate signal when the detected heat from a diamond is greater than a predetermined value. The diamonds could, for instance, be conveyed on conveyor belt and subjected to the relevant field or radiation while on the belt. The infra-red detectors could be aimed at the particles after they have passed through the field or radiation to detect the heated diamonds.
Thereafter the type IIB diamonds could be separated from the other diamonds, in response to signals from the detector, by microprocessor controlled fluid blast ejectors or the like.
Separation techniques of this kind are well known in the art.
As another alternative, the diamonds could, after passing through the relevant field, be dropped onto the surface of a body of ice. The various parameters, such as ice temperature and resistence time, would be chosen for the hot type IIB diamond to melt into the ice and thereafter be embedded in the ice when the ice refreezes. The cooler diamonds would have insufficient heat content to melt the ice and would therefore rest loosely on the ice surface. Physical separation could then be achieved merely by sweeping the surface of the ice to remove the loose diamonds, leaving only the type IIB diamonds embedded in the surface of the ice.

Claims (12)

1.
A method of distinguishing type IIB diamonds from other diamonds, the method comprising the steps of subjecting the diamonds to a varying magnetic field or to electromagnetic radiation, the field or radiation being chosen to generate eddy currents in type IIB diamonds, and identifying type IIB diamonds as those diamonds which are heated up to a level greater than a predetermined level.
2.
A method according to claim 1 wherein the diamonds are subjected to high frequency electromagnetic radiation in the microwave or radio wave part of the electromagnetic spectrum.
3.
A method of sorting type IIB diamonds from other diamonds, the apparatus comprising means for subjecting the diamonds to a varying magnetic field or to electromagnetic radiation, the field or radiation being chosen to generate eddy currents in type IIB diamonds, and sorting the diamonds on the basis of the level to which they are heated up.
4.
A method according to claim 3 wherein the level to which the diamonds are heated up is determined with the use of infrared detectors.
5.
A method according to claim 3 wherein the diamonds are sorted by placing them on a body of ice so that hotter diamonds lose heat to the ice, melt the ice and are subsequently captured by the ice when the ice refreezes while cooler diamonds are not able to melt the ice and therefore remain uncaptured by the ice.
6.
Apparatus for distinguishing. type IIB diamonds from other diamonds, the apparatus comprising means for subjecting the diamonds to a varying magnetic field or to electromagnetic radiation, the field or radiation being chosen to generate eddy currents in type IIB diamonds, and means for identifying the type IIB diamonds as those diamonds which are heated up to level greater than a predetermined level.
7.
Apparatus according to claim 6 wherein the identifying means comprises an infra red detector.
8.
Apparatus for sorting type IIB diamonds from other diamonds, the apparatus comprising means for subjecting the diamonds to a varying magnetic field or to electromagnetic radiation, the field or radiation being chosen to generate eddy currents in type IIB diamonds, and means for sorting type IIB diamonds from other diamonds on the basis of the level to which they are heated up.
9.
Apparatus according to claim 8 wherein the sorting means comprises an infra-red detector and separating means, responsive to the detector, for separating hotter diamonds from cooler diamonds.
10.
Apparatus according to claim 8 wherein the sorting means comprises a body of ice, means for placing the diamonds on the body of ice, and means for removing from the ice diamonds which have not melted the ice and been captured by the ice upon refreezing of the ice.
11.
A method of sorting type IIB diamonds substantially as -- hereinbefore described.
12.
Apparatus for sorting type IIB diamonds constructed and arranged to operate substantially as hereinbefore described.
GB9026571A 1989-12-06 1990-12-06 Method and apparatus for IIB diamond sorting Expired - Fee Related GB2239519B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
ZA899316 1989-12-06

Publications (3)

Publication Number Publication Date
GB9026571D0 GB9026571D0 (en) 1991-01-23
GB2239519A true GB2239519A (en) 1991-07-03
GB2239519B GB2239519B (en) 1993-11-17

Family

ID=25579929

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9026571A Expired - Fee Related GB2239519B (en) 1989-12-06 1990-12-06 Method and apparatus for IIB diamond sorting

Country Status (3)

Country Link
AU (1) AU631700B2 (en)
BR (1) BR9006198A (en)
GB (1) GB2239519B (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2278440A (en) * 1993-05-26 1994-11-30 De Beers Ind Diamond Particle classification based on thermal properties
CN103645122A (en) * 2013-11-05 2014-03-19 中国科学院电工研究所 On-line ferromagnetic-particle detection system
WO2019180718A1 (en) * 2018-03-23 2019-09-26 Ariel Scientific Innovations Ltd. Method and device for grading diamonds

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2076146A (en) * 1980-01-25 1981-11-25 Gunsons Sortex Mineral & Autom Method and Apparatus for Sorting
GB2184043A (en) * 1985-12-11 1987-06-17 De Beers Ind Diamond Separation of particles having different heat capacities and coefficients of thermal conductivity

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU7097887A (en) * 1986-04-03 1987-10-08 De Beers Industrial Diamond Division (Proprietary) Limited Sorting ore particles
GB2198242B (en) * 1986-11-28 1990-10-17 De Beers Ind Diamond Method and apparatus for sorting particulate ore by microwave attenuation

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2076146A (en) * 1980-01-25 1981-11-25 Gunsons Sortex Mineral & Autom Method and Apparatus for Sorting
GB2184043A (en) * 1985-12-11 1987-06-17 De Beers Ind Diamond Separation of particles having different heat capacities and coefficients of thermal conductivity

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2278440A (en) * 1993-05-26 1994-11-30 De Beers Ind Diamond Particle classification based on thermal properties
GB2278440B (en) * 1993-05-26 1996-08-21 De Beers Ind Diamond Classification based on thermal properties
CN103645122A (en) * 2013-11-05 2014-03-19 中国科学院电工研究所 On-line ferromagnetic-particle detection system
CN103645122B (en) * 2013-11-05 2016-01-20 中国科学院电工研究所 Online ferromagnetic microparticles detection system
WO2019180718A1 (en) * 2018-03-23 2019-09-26 Ariel Scientific Innovations Ltd. Method and device for grading diamonds
US11835473B2 (en) 2018-03-23 2023-12-05 Ariel Scientific Innovations Ltd. Method and device for grading diamonds using radiofrequency (RF) spectroscopy

Also Published As

Publication number Publication date
GB2239519B (en) 1993-11-17
AU6780690A (en) 1991-06-13
AU631700B2 (en) 1992-12-03
BR9006198A (en) 1991-09-24
GB9026571D0 (en) 1991-01-23

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 19961206