GB2101304A - Gold ore sorting - Google Patents
Gold ore sorting Download PDFInfo
- Publication number
- GB2101304A GB2101304A GB08215251A GB8215251A GB2101304A GB 2101304 A GB2101304 A GB 2101304A GB 08215251 A GB08215251 A GB 08215251A GB 8215251 A GB8215251 A GB 8215251A GB 2101304 A GB2101304 A GB 2101304A
- Authority
- GB
- United Kingdom
- Prior art keywords
- ore
- lumps
- cylinders
- neutrons
- lump
- 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
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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
- G01N23/221—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
- G01N23/222—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 using neutron activation analysis [NAA]
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- 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
-
- 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
- G01N23/02—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 transmitting the radiation through the material
- G01N23/06—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 transmitting the radiation through the material and measuring the absorption
- G01N23/12—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 transmitting the radiation through the material and measuring the absorption the material being a flowing fluid or a flowing granular solid
-
- 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
- G01N2223/074—Investigating materials by wave or particle radiation secondary emission activation analysis
- G01N2223/0745—Investigating materials by wave or particle radiation secondary emission activation analysis neutron-gamma activation analysis
-
- 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
- G01N2223/60—Specific applications or type of materials
- G01N2223/635—Specific applications or type of materials fluids, granulates
Landscapes
- Physics & Mathematics (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)
- Analysing Materials By The Use Of Radiation (AREA)
Abstract
Apparatus for sorting lumps of gold-bearing ore according to their gold content, includes means for irradiating the lumps of ore with neutrons, comprising e.g. voltage accelerator 2, drift tube 3 and titanium deuteride target 4 means for measuring the intensity of gamma -rays having an energy of 297 keV arising from the nuclear reaction <197>Au(nn' gamma )<197>Au; and means responsive to the measured gamma -ray intensity from a given lump of ore to sort that lump of ore from other lumps of ore; wherein the means for irradiating the lumps comprises a high voltage accelerator neutron tube adapted to produce at least 10<10> neutrons per second with an energy of less than 4.5 MeV, and means including e.g. cylinders 5, 6, 7 and vibrator 8 for presenting the lumps of ore to the neutrons in a geometrical configuration, such as to enable the lumps of ore to be irradiated uniformly. <IMAGE>
Description
SPECIFICATION
Improvements in or relating to gold ore sorting
The present invention relates to the measurement of the gold content of gold-bearing ores, and the sorting of individual lumps of goldbearing ore according to their gold content.
A practicable gold sorting plant needs to be able to process several tons or ore an hour. Hence it must utilise a very rapid analytical technique. A suitable analytical technique is neutron activation analysis, using the reaction 197 Au (n,n'y) 197m Au to activate the gold present in each lump of ore, and then measuring the intensity of the resultant y-rays having an energy of 297 keV and â half-life of 7.8 seconds. It is necessary to ensure that there is a high yield of 197m Au nuclei and that the lumps of ore are activated uniformly, that is to say, every lump of ore of the same gold grate (total gold content/mass) has the same specific activity (total mass of 197m Au nuclei/mass).
According to the present invention there is provided an apparatus for sorting lumps of goldbearing ore according to their gold content, including means for irradiating the lumps of ore with neutrons, means for measuring the intensity of y-rays having an energy of 297 KeV arising from the nuclear reaction 197 Au (nn,n'y) 197m Au, and means responsive to the measured y-ray intensity from a given lump of ore to sort that lump of ore from other lumps of ore, wherein the means for irradiating the lumps of ore with neutrons comprises a high voltage accelerator neutron tube adapted to produce at least 10'0 neutrons per second with an energy less than 4.5
MeV, and means for presenting the lumps of ore to the neutrons in a geometrical configuration such as to enable the lumps of ore to be irradiated uniformly with neutrons.
The invention will now be described, by way of example, with reference to the accompanying drawings, in which
Figure 1 is a diagrammatic representation of part of an ore sorting apparatus incorporating the invention,
Figure 2 is a diagrammatic representation of another part of the sorting apparatus embodying the invention,
Figure 3 is a diagrammatid representation of part of a second embodiment of the invention, corresponding to that shown in Figure 1, and
Figure 4 is a diagrammatic representation of part of a third embodiment of the invention corresponding to that shown in Figure 1.
Referring to Figure 1, a beam of deutrons 1 from a high voltage accelerator 2 passes along a drift tube 3 and impinges on a target 4 made of titanium deuteride (TiD2). Positioned symmetrically about the deuteron drift tube 2 and target 4 are three vertical cylinders, 5, 6 and 7, respectively, which are arranged to be rotated about their longitudinal axes by means of electric motors, which are not illustrated. The cylinder 5, has its axis of rotation on the line of flight of the deuteron beam 1. The cylinder 5 has a diameter which is approximately 1.5 times that of the cylinders 6 and 7. Prior to their arrival at the cylinders 5, 6 and 7, lumps of ore are sorted into two sizes, the larger ones being directed into the cylinder 5 and the smaller ones into the cylinders 6 and 7.
Fifty per cent of the throughput of the plant passes through the cylinder 5 and twenty five per cent passes through each of the cylinders 6 and 7.
The rates of feed and withdrawal from the cylinders 5,6 and 7 are arranged to be such that the linear speed of the lumps of rock through the cylinders 5, 6 and 7 is so matched to the rate of rotation of the cylinders 5, 6 and 7, that each lump of ore traverses the high intensity region of the neutron field the same integral number of times.
For example, if the length of the target 4 is 11 cm (parallel to the axes of the cylinders 5, 6 and 7) a linear velocity of the lumps of ore through the cylinders 5, 6 and 7 of 5.5 cm/s results in two complete passages of the lumps of ore through the neutron field.
A convenient way of controlling the outlet of the lumps of ore from the cylinders 5, 6 and 7, which is a vital factor in maintaining a uniform level of activation of the gold in the lumps of ore, is to use a vibrator 8 at the outlet end of each of the cylinders 5, 6 and 7.
Upon leaving the cylinders 5, 6 and 7, the irradiated lumps of ore are carried on three conveyor belts 9 to a detector/sorter station one channel of which is illustrated in Figure 2. In fact, to facilitate the rapid measurement of the activity of the irradiated lumps of ore, which is necessary because of the short half-life of 197m Au, twelve such channels are used, four being served by each conveyor belt 9. Each measurement channel consists of a rotating wheel 21 the periphery of which is divided into fifty compartments 22. Each compartment 22 has associated with it a scintillation radiation detector 23. The radiation detectors 23 are separated by lead screens 24 so that a lump of ore in one compartment 22 cannot affect the measurement of the activity of another lump of ore in another compartment 22. Lead shields also are interposed between each of the wheels 21.The lumps of ore are held close to the detectors 23 by means of a pressure belt 22' which serves also as a conveyor belt conveying lumps of ore after they have been analysed to an accept/reject gate 25. The accept/reject gate 25 feeds two further conveyor belts 26 and 27, respectively.
Each detector 23 has associated with it an electronic measuring unit 28, the output signals from which are fed to a slip ring 29 at the centre of the wheel 21, whence they are taken to an electro-magnetic actuator, not shown, for a simple gate flap 25' in the accept/reject gate 25.
Figure 3 shows another form of irradiator in which the deuteron drift tube 3 is mounted vertically and the target 4 is mounted horizontally.
The cylinders 5, 6 and 7 are replaced by two identical horizontally opposed feed channels 31 only one of which will be described. The lumps of ore are fed into the feed channels 31 from separate supplies so that the smaller rocks lie at the bottom in the region of the highest intensity of the neutron field. As a result, although the neutron field is not uniform, near uniformity of activation of 197m Au nuclei is obtained. After activation, the lumps of ore are released in batches by means of a control gate 32 into a holding chamber 33 whence they are released by a second control gate 34.
The rate of movement of the lumps of ore through the region of maximum neutron field is arranged to be such that the rate of production of 197m Au nuclei is maximised. The use of two opposed feed channels doubles the throughput available with one feed channel.
After release from the holding chamber 33 the lumps of ore pass to a detector station such as that already described.
The holding chamber 33 regularises the flow of irradiated lumps of ore. The loss of 197m Au nuclei which occurs during the regularising process is compensated for by arranging for the dimensions of the holding chamber 33 to be such that an appropriate amount of further activation takes place in the weak neutron field to which it is subjected.
A third arrangement for irradiating the lumps of ore is shown in Figure 4. In this arrangement, the deuteron drift tube 3 and target 4 are positioned as for the arrangement described with reference to Figure 3, but the horizontal feed channels 31 are replaced by four vertical feed channels 41. As before, the lumps of ore are sorted into two sizes. The smaller lumps of ore are passed through the inner feed channels 41 so that they are subjected to a more intense neutron field than the larger lumps of ore. The field gradient is allowed for by causing the lumps of ore in the inner channels 41 to pass through them at a higher velocity than those passing through the outer channels 41. The feed rates are controlled by four vibrators 42, one fast and one slow per side.
This arrangement enables the two sizes of lumps of ore to be kept separate during the detection stage, if desired.
Claims (14)
1. Apparatus for sorting lumps of gold-bearing ore according to their gold content, including means for irradiating the lumps of ore with neutrons, means for measuring the intensity of yrays having an energy of 297 KeV arising from the nuclear reaction 197 Au (nn, n' y) 197m Au, and means responsive to the measured y-ray intensity from a given lump of ore to sort that lump of ore from other lumps of ore, wherein the means for irradiating the lumps of ore with neutrons comprises a high voltage accelerator neutron tube adapted to produce at least 10'0 neutrons per second with an energy less than 4.5 MeV, and means for presenting the lumps of ore to the neutrons in a geometrical configuration such as to enable the lumps of ore to be irradiated uniformly with neutrons.
2. Apparatus according to Claim 1, wherein the neutrons are produced from a target which is bombarded by a beam of deuterons, wherein the means for presenting the lumps ore to be irradiated evenly comprises three parallel cylinders disposed at the vertices of an isosceles triangle with one cylinder having a diameter approximately 1.5 times that of the other two, the cylinders being so positioned that the large cylinder has its longitudinal axis on the line of flight of the beam of deuterons and perpendicular thereto and the smaller cylinders are disposed symmetrically about the line of flight of the deuterons so as to enclose the neutron producing target, means for sorting the lumps of ore into two sizes and directing the larger size of lumps of ore to the large cylinder and half the smaller lumps of ore to each of the smaller cylinders, and means for rotating the cylinders at speeds such that each lump of ore passes through the high intensity region of the neutron field the same number of times during its passage through the cylinders.
3. Apparatus according to Claim 2, wherein the direction of flight of the deuteron beam is horizontal, the cylinders are vertical, and the lumps of ore pass through the cylinders under the influence of gravity.
4. Apparatus according to Claim 3, wherein the speed of passage of the lumps of ore through the cylinders is controlled by vibrating screens at the outlets of the cylinders.
5. Apparatus according to Claim 1, wherein the neutron tube has an elongated target and there is included at least one horizontally positioned feed channel arranged to terminate in the neighbourhood of the elongated target which is positioned so that it lies approximately in the same plane as the bottom of the feed channel with its longitudinal axis at right angles to that of the feed channel, means for supplying lumps of ore to the feed channel in such a manner that the lumps of ore in the feed channel are graded in size with the smallest lumps of ore at the bottom of the feed channel and the largest lumps are at the top, and means for releasing of lumps of ore from the end of the feed channel after they have been irradiated by neutrons.
6. Apparatus according to Claim 5, wherein there is included a holding chamber arranged to receive lumps of ore from the feed control means for releasing the irradiated lumps of ore in batches to the means for measuring the intensity of y-rays having an energy of 297 KeV arising from the nuclear reaction 197 Au(nn,nty) 197m Au.
7. Apparatus according to Claim 6, wherein the holding chamber is so positioned that the lumps of ore within it are subjected to further irradiation by neutrons prior to their release.
8. Apparatus according to Claim 6 or Claim 7, wherein there is provided two horizontally opposed feed channels.
9. Apparatus according to Claim 1, wherein the neutron tube has an elongated target mounted with its longitudinal axis substantially horizontal, and there is provided at least one pair of vertical feed channels having a rectangular cross-section with the major axis parallel to the longitudinal axis of the target, means for grading the lumps of ore into two sizes and supplying the smaller lumps of ore to the feed channel which is closer to the target of the neutron tube, and means for causing the larger size of lumps of ore to pass through the neutron field at a slower rate than that of the smaller lumps of ore so as to compensate for the reduced neutron intensity in the feed channel through which the larger lumps of ore pass.
1 0. Apparatus according to any preceding claim, wherein the means for measuring the intensity of y-rays having an energy of 297 KeV includes a plurality of receptacles, each adapted to receive a single lump of ore and bring it into juxtaposition with a y-ray detector which is responsive to the said y-ray.
11. Apparatus according to Claim 10, wherein the receptacles are disposed around the periphery of at least one rotatable member.
12. Apparatus according to Claim 11, wherein each receptacle has an associated y-ray detector.
13. Apparatus according to Claim 11 or Claim 12, wherein the rotatable member is a wheel or drum.
14. Apparatus according to Claim 11, Claim 12, or Claim 13, wherein there is included means for releasing each lump of ore from its receptacle at an outlet station at which there is situated a selector which is arranged to operate in response to a signal received from the y-ray detector relating to each lump of ore as it is released so as to accept or reject that lump of ore for processing.
1 5. Apparatus substantially as hereinbefore described with reference to the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08215251A GB2101304B (en) | 1981-06-10 | 1982-05-25 | Gold ore sorting |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8117854 | 1981-06-10 | ||
| GB08215251A GB2101304B (en) | 1981-06-10 | 1982-05-25 | Gold ore sorting |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2101304A true GB2101304A (en) | 1983-01-12 |
| GB2101304B GB2101304B (en) | 1985-06-12 |
Family
ID=26279756
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08215251A Expired GB2101304B (en) | 1981-06-10 | 1982-05-25 | Gold ore sorting |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2101304B (en) |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1984004393A1 (en) * | 1983-04-22 | 1984-11-08 | Atomic Energy Authority Uk | Ore irradiator |
| WO1984004707A1 (en) * | 1983-05-20 | 1984-12-06 | Atomic Energy Authority Uk | Ore sorting apparatus |
| FR2555750A1 (en) * | 1983-11-30 | 1985-05-31 | Gen Mining Union Corp | METHOD AND DEVICE FOR ACTIVATION OF A SELECTED SUBSTANCE IN A MATERIAL IN THE FORM OF PARTICLES |
| EP0171256A2 (en) * | 1984-08-10 | 1986-02-12 | Gamma-Metrics | Self-contained, on-line, real-time bulk material analyzer |
| GB2193312A (en) * | 1986-07-29 | 1988-02-03 | Atomic Energy Authority Uk | Flint-in-chalk sorting |
| FR2618225A1 (en) * | 1987-07-15 | 1989-01-20 | France Etat Ponts Chaussees | METHOD AND INSTALLATION FOR NEUTRONIC BOMBING ANALYSIS OF A FLOW OF BULK MATERIALS |
| US5162095A (en) * | 1987-07-15 | 1992-11-10 | L'etat Francais | Method and installation for the analysis by neutron activation of a flow of material in bulk |
| FR2869107A1 (en) * | 2004-04-14 | 2005-10-21 | Sarp Ind Sa | Use of neutron activation technique to determine physical-chemical composition of mixed waste materials |
| RU2507509C1 (en) * | 2012-07-12 | 2014-02-20 | Федеральное государственное бюджетное учреждение науки Институт геологии рудных месторождений, петрографии, минералогии и геохимии Российской академии наук (ИГЕМ РАН) | Method for determining gold content of mine rocks |
| CN114226278A (en) * | 2021-11-26 | 2022-03-25 | 安徽理工大学 | Small-size wide particle size grade coal gangue sorting unit |
-
1982
- 1982-05-25 GB GB08215251A patent/GB2101304B/en not_active Expired
Cited By (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1984004393A1 (en) * | 1983-04-22 | 1984-11-08 | Atomic Energy Authority Uk | Ore irradiator |
| US4898709A (en) * | 1983-04-22 | 1990-02-06 | United Kingdom Atomic Energy Authority | Ore irradiator |
| US4702379A (en) * | 1983-05-20 | 1987-10-27 | United Kingdom Atomic Energy Authority | Ore sorting apparatus |
| WO1984004707A1 (en) * | 1983-05-20 | 1984-12-06 | Atomic Energy Authority Uk | Ore sorting apparatus |
| FR2555750A1 (en) * | 1983-11-30 | 1985-05-31 | Gen Mining Union Corp | METHOD AND DEVICE FOR ACTIVATION OF A SELECTED SUBSTANCE IN A MATERIAL IN THE FORM OF PARTICLES |
| DE3443527A1 (en) * | 1983-11-30 | 1985-06-05 | General Mining Union Corp. Ltd., Johannesburg, Transvaal | METHOD AND DEVICE FOR ACTIVATING MATERIAL |
| US4696782A (en) * | 1983-11-30 | 1987-09-29 | United Kingdom Atomic Energy Authority | Ore irradiator |
| EP0171256A2 (en) * | 1984-08-10 | 1986-02-12 | Gamma-Metrics | Self-contained, on-line, real-time bulk material analyzer |
| EP0171256A3 (en) * | 1984-08-10 | 1986-11-26 | Gamma-Metrics | Self-contained, on-line, real-time bulk material analyzer |
| GB2193312A (en) * | 1986-07-29 | 1988-02-03 | Atomic Energy Authority Uk | Flint-in-chalk sorting |
| FR2618225A1 (en) * | 1987-07-15 | 1989-01-20 | France Etat Ponts Chaussees | METHOD AND INSTALLATION FOR NEUTRONIC BOMBING ANALYSIS OF A FLOW OF BULK MATERIALS |
| WO1989000685A1 (en) * | 1987-07-15 | 1989-01-26 | ETAT FRANÇAIS, représenté par le MINISTERE DE L'EQ | Process and installation for analysing a flow of bulk materials by neutron bombardment |
| GR880100468A (en) * | 1987-07-15 | 1989-04-12 | Lafarge Ciments Sa | Method and installation of analysis by means of neutrons of a material flow |
| AU606450B2 (en) * | 1987-07-15 | 1991-02-07 | Ciments Lafarge | Process and installation for analysing a flow of bulk materials by neutron bombardment |
| US5162095A (en) * | 1987-07-15 | 1992-11-10 | L'etat Francais | Method and installation for the analysis by neutron activation of a flow of material in bulk |
| FR2869107A1 (en) * | 2004-04-14 | 2005-10-21 | Sarp Ind Sa | Use of neutron activation technique to determine physical-chemical composition of mixed waste materials |
| RU2507509C1 (en) * | 2012-07-12 | 2014-02-20 | Федеральное государственное бюджетное учреждение науки Институт геологии рудных месторождений, петрографии, минералогии и геохимии Российской академии наук (ИГЕМ РАН) | Method for determining gold content of mine rocks |
| CN114226278A (en) * | 2021-11-26 | 2022-03-25 | 安徽理工大学 | Small-size wide particle size grade coal gangue sorting unit |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2101304B (en) | 1985-06-12 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |