AU704679B2 - Rock sorting - Google Patents
Rock sorting Download PDFInfo
- Publication number
- AU704679B2 AU704679B2 AU45878/96A AU4587896A AU704679B2 AU 704679 B2 AU704679 B2 AU 704679B2 AU 45878/96 A AU45878/96 A AU 45878/96A AU 4587896 A AU4587896 A AU 4587896A AU 704679 B2 AU704679 B2 AU 704679B2
- Authority
- AU
- Australia
- Prior art keywords
- rocks
- kimberlite
- radiation
- rock
- significant absorption
- 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.)
- Ceased
Links
- 239000011435 rock Substances 0.000 title claims description 82
- 238000010521 absorption reaction Methods 0.000 claims description 27
- 238000001228 spectrum Methods 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 15
- 230000005855 radiation Effects 0.000 claims description 11
- 239000010878 waste rock Substances 0.000 claims description 11
- 238000001514 detection method Methods 0.000 claims description 8
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 6
- 239000011707 mineral Substances 0.000 claims description 6
- 230000000717 retained effect Effects 0.000 claims description 4
- 230000003595 spectral effect Effects 0.000 claims description 4
- WYTGDNHDOZPMIW-RCBQFDQVSA-N alstonine Natural products C1=CC2=C3C=CC=CC3=NC2=C2N1C[C@H]1[C@H](C)OC=C(C(=O)OC)[C@H]1C2 WYTGDNHDOZPMIW-RCBQFDQVSA-N 0.000 claims description 2
- 229910003460 diamond Inorganic materials 0.000 claims description 2
- 239000010432 diamond Substances 0.000 claims description 2
- 238000000926 separation method Methods 0.000 claims description 2
- 229910021647 smectite Inorganic materials 0.000 claims description 2
- 235000013405 beer Nutrition 0.000 claims 1
- 230000009102 absorption Effects 0.000 description 20
- 239000011777 magnesium Substances 0.000 description 7
- 239000002699 waste material Substances 0.000 description 4
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000003801 milling Methods 0.000 description 2
- 229910018512 Al—OH Inorganic materials 0.000 description 1
- 208000035126 Facies Diseases 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 238000002835 absorbance Methods 0.000 description 1
- 229940000425 combination drug Drugs 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- GUJOJGAPFQRJSV-UHFFFAOYSA-N dialuminum;dioxosilane;oxygen(2-);hydrate Chemical compound O.[O-2].[O-2].[O-2].[Al+3].[Al+3].O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O GUJOJGAPFQRJSV-UHFFFAOYSA-N 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 229910052901 montmorillonite Inorganic materials 0.000 description 1
- 229910000273 nontronite Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3563—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing solids; Preparation of samples therefor
Landscapes
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Description
AUSTRALIA
Patents Act COMPLETE SPECIFICATION
(ORIGINAL)
Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art: Name of Applicant: De Beers Industrial Diamond Division (Proprietary) Limited Actual Inventor(s): Suha Rawhani Address for Service: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Invention Title: ROCK SORTING Our Ref 443647 POF Code: 1503/78726 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): 2 BACKGROUND TO THE INVENTION THIS invention relates to the sorting of rocks to separate waste rock from potentially valuable rock or rock possibly containing valuable minerals.
Rocks contairtng valuable minerals generally need to be treated extensively in order to extract a suitably high percentage of the available mineral from the rock. However, during the mining operation and thereafter, waste rock is frequently mined and mixed with the high value rock. It is desirable that S the waste rock is separated from the high value rock as early as possible, prior to treatment, so that the treatment process is not applied to waste rock with the consequent wastage of energy and resources.
There are various known kinds of sorting equipment in which the rocks to be sorted are moved through a detection system which assesses the degree to which the particular rocks in the stream exhibit a specific characteristic.
Individual rocks in the stream are either selected or rejected, depending on the results of the analysis performed by the detector. The apparatus for selecting or rejecting the rocks can take one of various forms including air blast nozzles or separating gates, and the apparatus which will be used will generally depend on the size of the rocks to be separated.
~slslar -e- Kimberlite, wihis niinel to recover diamronds contained within the rock, is generally difficult to autorratically separate from waste rock. It has been foutid that in manyv kinber lite processing plants such -waste rock can constitute a :ar-e proportion of milling and processing plant fee-d. Detectors of prior art sorting apparatus have been used to identify the waste rock to enable that rock ton be rejected during the selection! rejection stage of the sorting operation. Thc problem widi dtus pior ar-t process is that, for each possible type of waste roo:k. a different or differently configured detection systemn is rcquirci.
SUMMARY OF THE INVENTION According to the present invention there is provided a method of sorting kimberlite rocks from other rocks, the method including the steps of: moving rocks which are to be sorted through a scanning zone; scanning the rocks to measure values of spectral reflectance over their surfaces at a plurality of different wavelengths in the short-wave infrared region of the electromagnetic spectrum; identifying as kimberlite rocks those rocks which display significant absorption of radiation, indicative of the presence in the rocks of MgOH bonds, in the wavelength range 1800nm to 2450nm; and separating the rocks to retain those rocks identified as kimberlite rocks.
The present invention also provides an apparatus for sorting kimberlite rocks from other rocks, the apparatus including: conveyance means for conveying rocks which are to be sorted through a scanning zone; scanning and detection means for scanning the rocks individually as they pass through the scanning zone and for detecting values of spectral 20 reflectance over their surfaces at a plurality of wavelengths in the short-wave infrared region of the electromagnetic spectrum; analysis means for analysing the detected values and for identifying as kimberlite rocks those rocks which display significant absorption of radiation, indicative of the presence of MgOH bonds in the rocks, in the wavelength range 25 1800nm to 2450nm; and separation means for separating the rocks into retained and Sdiscarded fractions with the rocks that are separated into the retained fraction being those identified as kimberlite rocks.
Accordingly, there is provided a rock detection or discrimination system which measures reflectance in the short-wave infrared region of the electromagnetic spectrum, and which is adapted to detect significant absorption associated with Mg-OH bonds in the rock under analysis.
1% 1, f k\k. 4 5 This significant absorption generally occurs in the range of 1850 to 2450 nm, and, more specifically at about 2305 to 2325 nm, typically 2316 nm, and again at about 2380 to 2400 nm, typically 2390 nm.
Any convenient detection or discrimination system can be employed but a preferable system includes the following features: A source of short-wave infrared radiation which radiates the mixed rock pieces, and a detector or discriminator which can identify those pieces which have a higher absorbance of the radiation than others.
Features of the invention are described in detail in the following passages of the specification which refer to the accompanying graphs. The graphs depict .results of tests conducted with test apparatus on kimberlite materials obtained from different deposits.
DETAILED DESCRIPTION Kimberlite is suitable for detection in accordance with the method of the invention, since kimberlite rocks generally include minerals such as serpentine or smectite which have an Mg-OH bond which is detectable in the short-wave infrared region of the electro-magnetic spectrum.
Figure 1 graph shows the results of tests conducted on various samples from a kimberlite deposit referred to as deposit A. Samples 479 and 480 are samples of volcaniclastic kimberlite and it should be noted that each of these sample show a significant absorption of radiation at approximately 2316 nm, showing the presence of magnesium. Samples 495 and 496 are samples of waste basalt which, in practice, should be discarded prior to milling and processing of the kimberlite. The basalt spectra are different in a number of ways: a) the absorption feature are very broad and much shallower, This is not obvious in Figure 1 as the basalt spectra have both been vertically exaggerated; b) sample 496 has a small Mg absorption and also has a slightly stronger Fe absorption at approximately 2285 nm; and c) neither of the basalt samples have sharp asymmetrical absorption at around 1400 nm.
It should be noted that the large absorption at approximately 1900 nm is due to the presence of water.
*o In Figure 2, spectra of rocks obtained from deposit A have been plotted.
The samples are an inter-bedded epiclastic grit (samples 497) the spectra of which have been plotted alongside a spectrum for a kimberlite autolith (sample 499). The kimberlite autolith shows a significant absorption at 2316 nm and 2395 nm. The samples 497 slo-w combinat-ion of Mg and Fe features as would be expected. The difference between the "grit" and "shale" samples show a decrease in the strength of the Mg absorption and a corresponding increase in the strength of the F; absorption.
Figure 3 depicts spectra of four different kimberlite samples obtained from deposit B all of which have the characteristic Mg absorptions and asymmetric feature at 1400 nm.
-p c 7 In Figure 4 sample 596 obtained from deposit B displays the characteristic absorptions at 2316 nm and 2390 nm whereas the sample 1107 (waste) plotted with a large vertical exaggeration and shows a rather featureless spectrum with a different overall shape to the kimberlite sam le. The two samples are, accordingly, easily distinguishable.
Figures 5 and 6 depict samples obtained from deposit C. Crater facies samples numbered 770 and 779 in Figure 5 and 904 in Figure 6 all show I' strong Mg features. Sample 755, which has been labelled as a questionable volcaniclastic material shows predominantly Fe features and only a small primary Mg absorption. This indicates that the sample contains vary little kimberlite maerial. The shale breccia sample (751) spectrum has a dominant Al-OH absorption at 2312 nm and a secondary absorption at 2350 nrn and 2345 nm indicating the presence ofmuscovite. The khaki mudstone (sample 756) has only a weak, broad Al absorption around 2210 nm while sample 908, the dark green mudstone, has strong absorption at 2285 nm and 2392 nm indicating the presence of nontronite, and Fe-rich montmorillonite.
From the aforegoing it will be appreciated that the kimberlite samples are generally spectrally distinguishable from the country or waste rock contaminants. Clearly only a limited number of spectra are shown and more detailed analysis of the spectra will need to be made with a greater number of samples in order to accurately and reliably distinguish between kimberlite and waste rocks.
It will, however, be appreciated that the scanning system disclosed effectively "recognises" and distinguishes kimberlite rocks from other rock types, hence ensuring that the system is somewhat more universal than other 8 waste rock sorting systems, which generally work on the principle of identifying the waste rock and discarding that rock, As has previously been mentioned 1 the sorting system can be of any suitable construction and the means for selecting or rejecting rock particles from the stream being analysed need not be described herein in any greater detail.
o 0* 0 0 a *1 0 0 00 00 0 .0 00 0 0 0 **00 0 0000 00 0 0 000 0
Claims (11)
1. A method of sorting kimberlite rocks from other rocks, the method including the steps of: moving rocks which are to be sorted through a scanning zone; scanning the rocks to measure values of spectral reflectance over their surfaces at a plurality of different wavelengths in the short-wave infrared region of the electromagnetic spectrum; identifying as kimberlite rocks those rocks which display significant absorption of radiation, indicative of the presence in the rocks of MgOH bonds, in the wavelength range 1800nm to 2450nm; and separating the rocks to retain those rocks identified as kimberlite rocks.
2. A method according to claim 1 wherein the wavelength range is 2305nm to 2325nm. S.
3. A method according to claim 2 wherein rocks are identified as kimberlite rocks if they display significant absorption of radiation at a wavelength of 2316nm.
4. A method according to claim 1 wherein the wavelength range is 2380nm to 2400nm.
5. A method according to claim 4 wherein rocks are identified as kimberlite 25 rocks if they display significant absorption of radiation at a wavelength of 2390nm.
6. An apparatus for sorting kimberlite rocks from other rocks, the apparatus including: conveyance means for conveying rocks which are to be sorted through a scanning zone; scanning and detection means for scanning the rocks individually as they pass through the scanning zone and for detecting values of spectral C W1-1-Z EWiW'^ flr-£ C NC- reflectance over their surfaces at a plurality of wavelengths in the short-wave infrared region of the electromagnetic spectrum; analysis means for analysing the detected values and for identifying as kimberlite rocks those rocks which display significant absorption of radiation, indicative of the presence of MgOH bonds in the rocks, in the wavelength range 1800nm to 2450nm; and separation means for separating the rocks into retained and discarded fractions with the rocks that are separated into the retained fraction being those identified as kimberlite rocks.
7. An apparatus according to claim 6 wherein the range is 2305nm to 2325nm.
8. An apparatus according to claim 7 wherein the analysis means is arranged to identify those rocks which display significant absorption of radiation at a wavelength of 2316nm as kimberlite rocks.
9. An apparatus according to claim 6 wherein the range is 2380nm to 2400nm.
10. An apparatus according to claim 9 wherein the analysis means is arranged to identify those rocks which display significant absorption of radiation at a wavelength of 2390nm as kimberlite rocks. 0 25
11. A method of sorting kimberlite rocks from other rocks, substantially as herein described with reference to the accompanying drawings. DATED: 4 March 1999 PHILLIPS ORMONDE FITZPATRICK Attorneys for: DE BEERS INDUSTRIAL DIAMOND DIVISION (PTY) LTD C f'f 1RSZ", E. e XC -II ABSTRACT To separate waste rock from potentially valuable rock or rock possibly containing valuable minerals, the rocks are passed through a rock detection or discrimination system which measures reflectance in the short-wave infrared region of the electromagnetic spectrum. The system is adapted to detect significant absorption associated with Mg-OH bonds in the rocks under analysis. The method is particularly suited to rocks which includes minerals such as serpentine or smectite having an Mg-OH bond which is detectable in the short-wave infrared region of the electromagnetic spectrum. The invention further extends to an apparatus which is adapted to carry out the method of the invention, 9 9 o 9* *o I
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA951833 | 1995-03-06 | ||
| ZA95/1833 | 1995-03-06 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU4587896A AU4587896A (en) | 1996-09-19 |
| AU704679B2 true AU704679B2 (en) | 1999-04-29 |
Family
ID=25584895
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU45878/96A Ceased AU704679B2 (en) | 1995-03-06 | 1996-03-05 | Rock sorting |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU704679B2 (en) |
| BR (1) | BR9600929A (en) |
| GB (1) | GB2298711B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20120306257A1 (en) | 2010-02-05 | 2012-12-06 | Katherine Silversides | Determination of rock types by spectral scanning |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4236640A (en) * | 1978-12-21 | 1980-12-02 | The Superior Oil Company | Separation of nahcolite from oil shale by infrared sorting |
| AU6048480A (en) * | 1979-07-24 | 1981-01-29 | Csr Limited | Infraed sorting |
| EP0064842A1 (en) * | 1981-05-12 | 1982-11-17 | Sphere Investments Limited | Material sorting |
-
1996
- 1996-03-05 AU AU45878/96A patent/AU704679B2/en not_active Ceased
- 1996-03-05 GB GB9604664A patent/GB2298711B/en not_active Expired - Fee Related
- 1996-03-06 BR BR9600929A patent/BR9600929A/en not_active Application Discontinuation
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4236640A (en) * | 1978-12-21 | 1980-12-02 | The Superior Oil Company | Separation of nahcolite from oil shale by infrared sorting |
| AU6048480A (en) * | 1979-07-24 | 1981-01-29 | Csr Limited | Infraed sorting |
| EP0064842A1 (en) * | 1981-05-12 | 1982-11-17 | Sphere Investments Limited | Material sorting |
Also Published As
| Publication number | Publication date |
|---|---|
| AU4587896A (en) | 1996-09-19 |
| GB2298711B (en) | 1999-06-30 |
| GB9604664D0 (en) | 1996-05-01 |
| GB2298711A (en) | 1996-09-11 |
| BR9600929A (en) | 1997-12-30 |
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