AU617807B2 - Diamond detection - Google Patents

Description

617807 COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952-1962 COMPLETE SPECIFICATION (Original) FOR OFFICE USE Class Int. Class Application Number: Lodged: Complete Specification Lodged; Accepted: Published: Priority: Related Art: Name of Applicant: DE BEERS INDUSTRIAL DIAMOND DIVISION (PROPRIETARY)

LIMITED

Address of Applicant: 45 MAIN STREET, JOHANNESBURG, TRANSVAAL, SOUTH AFRICA Actual Inventor(s): 1) LEE NORDIN 2) PETER JAMES SERGEANT Address for Service: DAVIES COLLISON, 1 LITTLE COLLINS STREET, MELBOURNE, VICTORIA, 9000, AUSTRALIA Complete Specification for the invention entitled; "DIAMOND DETECTION" The following statement is a full description of this invention, including the best method of performing it known tv me/us: Signature of declarant(s) (.o attestation required) Note: Initial 'all alterations.

I 1

U--IU-<

r C~ r It I -ay 2 BACKGROUND TO THE INVENTION THIS invention relates to diamond detection.

9000 9 0 0 0"1 o 0 000 9 9 0 0 0 00 0 o 00) 0 00 0) 09 00 0 OUU 0 00 0 0 '0 o Oo In the recovery of diamond from kimberlite it would obviously be advantageous to have m-ans for analysing the kimberlite particles before further processing takes place, to determine whether or not they are likely to contain diamonds. Then particles for which the analyses indicate the possible presence of one or more diamonds are the only particles which need to be processed further. In this way, it would be possible to reduce the overall operating costs of the recovery plant and the capacity of the further processing equipment, Once the kimberlite particles which are suspected of containing diamonds have been sepa::ated from other particles which are barren, and have been subjected to further processing to liberate the diamonds, it becomes necessary to separate diamond particles from particles of the host rock.

This is most commonly done at this stage using automatic X-ray sorting machines.

I F iL i -3- SUMMARY OF THE INVENTION The invention provides a diamond detection method which comprises subjecting particles of a particulate material to electromagnetic or particle beam energy from an external source, the energy to which the particles are subjected being chosen to cause particles of the particulate mass to emit acoustic signals, detecting the emitted acoustic signals, and analysing the emitted acoustic signals to determine which of the particles are diamond or diamondiferous particles.

The stimulating energy may be produced from any one of a number of different energy sources, such as an electromagnetic energy source producing laser radiation, o o° radio frequency radiation or X-radiation, or a source of SS. particle beam energy producing a, p or y radiation.

SPECIFIC DESCRIPTION The invention will now be described in more detail by way of example.

o i In a first example of the invention, kimberlite particles are subjected to stimulating energy from an external source such as one of those mentioned above. The characteristics of the stimulating energy are chosen to cause the kimberlite particles to emit acoustic energy which is detected using appropriate transducers. The detected acoustic energy is analysed to determine which of the particles is a likely host for one or more diamond particles. This may involve filtering out the acoustic signals to permit passage only of those signals indicative of the presence of diamond.

i 4, Particles which are suspected, on the basis of the determination described above, of being diamondiferous are then selected for further processing to liberate any diamond inclusions.

In a second example of the invention, it is assumed that diamondiferous kimberlite particles have previously been separated from barren kimberlite particles and have been processed further to liberate the diamonds. It is now necessary to sort the diamond particles from gangue particles. Once again, the individual particles are onao subjected to energy from an external energy source, 00 typically one of those referred to above and the stimulated acoustic emissions of the particles are detected and analysed to determine which of the particles are diamond 0,0 o particles and which are gangue particles. Acoustic filters 0o e0 may again be used.

In each example, the invention contemplates an automatic 0 sorting operation in which the particles are subjected, oV0 0 while flowing in a stream, to the stimulating energy, the stimulated acoustic emissions are detected and analysed, a o" determination is made by an electronic processor as to which of the particles is a diamondiferous kimberlite particle or a diamond, as the case may be, and the desired particles are automatically ejected from the stream, possibly using fluid blast ejectors such as are known in the art of particle sorting.

It is believed that laser light may be used to good advantage to provide the stimulating energy in both examples discussed above.

Claims (4)

1. 2. o,:I A diamond detection method according to claim 1 wherein the particles of the particulate material are subjected to laser .o radiation, X-radiation or radio frequency radiation from an 0 external source.
2. 3. S A diamond detection method according to claim 1 wherein the S0000 particles of the particulate material are subjected to a, f or y radiation from an external source. 0 0 0 00 S
3. 4. A diamond detection method according to any one of the preceding claims wherein the emitted acoustic signals are filtered to permit passage only of signals indicative of the presence of diamond. A diamond detection method according to any one of the preceding claims when used to detect particles of I -II -6- diamondiferous kimberlite.
4. 6. A diamond detection method according to any one of the preceding claims when used to detect diamond particles. 7 ,i A diamond detection method according to claim 5 when used in a particle sorting process in which diamondiferous kimberlite particles are sorted from other particles. A diamond detection method ccording to claim 6 when used in a particle sorting process in which diamond particles are sorted from other particles. &r II 4 Dated this 20th day of September, 1991 DAVIES COLLISON Patent Attorneys for DE BEERS INDUSTRIAL DIAMOND DIVISION (PROPRIETARY) LIMITED Tk ~v