AU600579B2 - Method and apparatus for evaluating the rare metal content of a natural geological formation - Google Patents
Method and apparatus for evaluating the rare metal content of a natural geological formation Download PDFInfo
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- AU600579B2 AU600579B2 AU16239/88A AU1623988A AU600579B2 AU 600579 B2 AU600579 B2 AU 600579B2 AU 16239/88 A AU16239/88 A AU 16239/88A AU 1623988 A AU1623988 A AU 1623988A AU 600579 B2 AU600579 B2 AU 600579B2
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- 229910052751 metal Inorganic materials 0.000 title claims description 56
- 239000002184 metal Substances 0.000 title claims description 56
- 230000015572 biosynthetic process Effects 0.000 title claims description 32
- 238000000034 method Methods 0.000 title claims description 19
- 230000005855 radiation Effects 0.000 claims description 24
- 238000001228 spectrum Methods 0.000 claims description 21
- 230000004913 activation Effects 0.000 claims description 14
- 230000003595 spectral effect Effects 0.000 claims description 13
- 238000005259 measurement Methods 0.000 claims description 9
- 239000010931 gold Substances 0.000 claims description 8
- 238000004458 analytical method Methods 0.000 claims description 7
- 238000001514 detection method Methods 0.000 claims description 7
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 6
- 229910052737 gold Inorganic materials 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 5
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 4
- 239000004065 semiconductor Substances 0.000 claims description 4
- 229910052709 silver Inorganic materials 0.000 claims description 4
- 239000004332 silver Substances 0.000 claims description 4
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 3
- 229910052732 germanium Inorganic materials 0.000 claims description 3
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 claims description 3
- 150000002343 gold Chemical class 0.000 claims description 3
- 239000011572 manganese Substances 0.000 claims description 3
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 2
- 229910052785 arsenic Inorganic materials 0.000 claims description 2
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 claims description 2
- 229910052797 bismuth Inorganic materials 0.000 claims description 2
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 claims description 2
- 239000011133 lead Substances 0.000 claims description 2
- 229910052748 manganese Inorganic materials 0.000 claims description 2
- 229910052763 palladium Inorganic materials 0.000 claims description 2
- 239000000523 sample Substances 0.000 claims description 2
- XSOKHXFFCGXDJZ-UHFFFAOYSA-N telluride(2-) Chemical compound [Te-2] XSOKHXFFCGXDJZ-UHFFFAOYSA-N 0.000 claims description 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 2
- 229910052721 tungsten Inorganic materials 0.000 claims description 2
- 239000010937 tungsten Substances 0.000 claims description 2
- 229910052725 zinc Inorganic materials 0.000 claims description 2
- 239000011701 zinc Substances 0.000 claims description 2
- 235000009917 Crataegus X brevipes Nutrition 0.000 claims 1
- 235000013204 Crataegus X haemacarpa Nutrition 0.000 claims 1
- 235000009685 Crataegus X maligna Nutrition 0.000 claims 1
- 235000009444 Crataegus X rubrocarnea Nutrition 0.000 claims 1
- 235000009486 Crataegus bullatus Nutrition 0.000 claims 1
- 235000017181 Crataegus chrysocarpa Nutrition 0.000 claims 1
- 235000009682 Crataegus limnophila Nutrition 0.000 claims 1
- 235000004423 Crataegus monogyna Nutrition 0.000 claims 1
- 240000000171 Crataegus monogyna Species 0.000 claims 1
- 235000002313 Crataegus paludosa Nutrition 0.000 claims 1
- 235000009840 Crataegus x incaedua Nutrition 0.000 claims 1
- 210000002837 heart atrium Anatomy 0.000 claims 1
- 239000004576 sand Substances 0.000 claims 1
- 238000005755 formation reaction Methods 0.000 description 26
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 5
- 238000010521 absorption reaction Methods 0.000 description 4
- 238000012550 audit Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 235000014698 Brassica juncea var multisecta Nutrition 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- YZCKVEUIGOORGS-OUBTZVSYSA-N Deuterium Chemical compound [2H] YZCKVEUIGOORGS-OUBTZVSYSA-N 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 241001247907 Mondia Species 0.000 description 1
- 241000251184 Rajiformes Species 0.000 description 1
- YZCKVEUIGOORGS-NJFSPNSNSA-N Tritium Chemical compound [3H] YZCKVEUIGOORGS-NJFSPNSNSA-N 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 229910052805 deuterium Inorganic materials 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000012188 paraffin wax Substances 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 230000002285 radioactive effect Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 238000004611 spectroscopical analysis Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910052722 tritium Inorganic materials 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V5/00—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V5/00—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity
- G01V5/04—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity specially adapted for well-logging
- G01V5/08—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity specially adapted for well-logging using primary nuclear radiation sources or X-rays
- G01V5/10—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity specially adapted for well-logging using primary nuclear radiation sources or X-rays using neutron sources
- G01V5/101—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity specially adapted for well-logging using primary nuclear radiation sources or X-rays using neutron sources and detecting the secondary Y-rays produced in the surrounding layers of the bore hole
Landscapes
- Physics & Mathematics (AREA)
- High Energy & Nuclear Physics (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- General Physics & Mathematics (AREA)
- Geophysics (AREA)
- Analysing Materials By The Use Of Radiation (AREA)
- Geophysics And Detection Of Objects (AREA)
Description
Pc]:
AU
1 I -1.6239/88 ORGANISATION MONDIA 61 PR.ORTE It LC~tf' DEMANDE INTERNATIONALE PUBLIEE EN VERTU DU TRAITE DE COOPERA~TION EN MATIERE DE BREVETS (P(.TI- (51) Classification internationale des brevets 4 Numikro de publication internationale: WVO 88/ j 343 G01V 5/00, 5/10 A2 (43) Date de publication internationale: octobre 1988 (20.10,88) (21) Num~ro de Ia demande internationale: PCT/FR88/00l84 (74) Mandataires: FORT, Jacques etc.: Cabinet Plasseraud, (22) Date de dip6t international: 14 avril 1988 (14.04.88) 8,redAsedm -50 ai F) (81) Etats dJsignks: AU, BR, FI, KR.
(31) Nunro, de Ia demande prioritaire: 87/05781 (32) Date de priorit6: 14 avril 1987 (14.04.87) Publii& Sans rapport de recherche intern ationale, sera republie (33) Pays de priori t6: FR d~s r~ception de ce rapport.
(71) Diposant: COM?'AGNIE GENERALE DES MA- TIERES NUCLEATRES [FR/FR], 2, rue Paul-Dautier, F-78141 Velizy-'l'illacoublay A. 0- J, P- 8 D EC 1988 (72) Inventeurs: DE BOURAYNE, Armand 2 bis, rue de la Grande-Fonltaine, F-78430 Louveciennes DE- LAIRE, Louis 61, rue Gros-Jacques, F-28350 Saint- Lubin-des-JonchereuL (FR).
AUSTRALIAN
4 NOV!98 Th, *dsnl-ument contains the PTN FI.
Jc-v~ u :U 1 sMatde un1der A NTOFC is con L't, for (54) Title: METHO0D AND APARATUS. FOR EVALUATING THE RARE METAL CONTENT OF A NATURAL GEOLOGICAL FORMATION (54) Titre; PROCEDE ET APPAREIIL D'E\ AL.UATION DE, LA TENEUR EN UN METAL P ARE D'UNE FORMA- TION GEOLOGIQUE NATURELLE (57) Abstract Method and apparatus for evaluating the rare metal content or a natural geological formation, wherein neutrons are emitted into the geological formation, the y radiation providing from elements r,ctivated by the neutrons is coII-.cted on a detector producing output pulses representative of the energy of the received y radiation, an energy histogram of the y radiation is formed by multi-c~hannel analysis, activation peaks characteristic of high intensity of at least one rich spectrum reference element associated with the nature of the searched rare metal or of the ram,~ metal itself as long as it has a rich spectrum are searched for, the count output of the pulses in re1ltion to the energy is deduced from the identification of the peaks of said reference element and from the '2 I intensity thereof, one or a plurality of lines of said rare metal are located and the contribution of said rare metal to the counting rate at said location is searched for, (57) Abrig6 ProcWd d'Evaluation de la teneur en metal rare d'unc forination g~ciogique naturelle, et appareil mettant en ceuvre ce proc~d6, dans lequel on 6met des neutrons dans la formation g~ologique, on recueille le rayonnement y provenant des 616ments activ~s par leg neutrons sur un d~tecteur fournissant des impulsions de sortie repr~sentatives de 1'6nergle du rayonnement y requ, on Constitue un histogramme eti 6nergie du rayonnement y par anialyse multi-canaux, on recherche dans E'histogramme les pics d'activation caract~ristiques de forte intensit6 d'au momns un-6l6ment de r6f~rence A spectre riche associ6 dans la nature au m~tal rare recherch6 ou du m~tal rare Iuimaine dans la mekure o t ii r un spectre riche, on d~duit de Ilidentification des pics dudit 6lament de r~farence et de leur intensit6 le rendement de comptage des impulsions en fonction de 1'6nergie, on rep~re 1'emplacement d~une ou plusleurs raies dudit m~tal rare et on recherche audit, emplacement la contribut!,on dludit m~tal rare au taux de comptage.
V ORAMSAIONMONDALEDE LA PROPRIETE INTELI-ECTUELLE FCT BureSTINMODauE international DEMANDE INTERNATIONALE PUBLIE3- EN VERTU DU TRAiTE DE COOPERATION EN MATIERE DE BREVETS (PCT) (51) Classification internationale des brevets 4 (11) Numno de publication internationale: WO 88/ 08143 G01V 5/00, 5/10 A3 (43) Date de publication Internationale: octobre 1988 (20.10.88) (21) Numnro de la deinande internationale: PCT/FR88/00 184 (74) Mandataires: FORT, Jacques etc.; Cabinet Plasseraud, 84, rue d'Amsterdam, F-75009 Paris (FR).
(22) Date de d~p6t international: 14 avril 1988 (14.04.88) (31) Numi~ro de la demnande prioritaire: 87/05281(8)Easfig6:AUBRFlK.
(32) Date de priorit6: 14 avril 1987 (14.04,87) Pub~ie A vec rapport de recherche internationale (33) Pays de priorit6: FR A vant 1'expiration du d~lai pr~vu pour la modification des revendcations, sera republie si de tel/es mod(/icatlons sont reques.
(71) D~posant: COMPAGNIE GENERALE DES MA- TIERES NUCLEAIRES [FR/FR]; 2, rue PauI-Dau- (88) Date de publication du rapport .ie recherche Internationale: tier, F-78 141 Velizy-Villacoublay 1_1 d~cembra 1988 (15,12,88) (72) Inventeurs: DE LOURAYNE, Armand 2 bis, rue de la Grande- Fontaine, F-78430 Louveciennes DE- LAIRE, Louis 61, rue Gros.Jacques, F.Z8350 Saint- Lubin-des-Joncherets (FR).
(54)Title: METHOD AND APPARATUS FOR EVALUATING THE RARE METAL CONTENT OF A NATURAL GEOLOGICAL FORMATION (54)Titre: PROCEDE ET APPAREIL D'EVALUATION DE LA TENEUR EN UN METAL RARE D'UNE FORMA- TION GEO LOGIQUE NATURELLE (57) 04b act Method and apparatus for evaluating the rare metal content of a natural geological formation, wherein neutrons are emitted into the geological formation, the y radiation providing from elements activated by the neutrons is collected on a detector producing output pulses representative of the energy of the received y radiation, an energy histogram of the y radiation is formed by multi-chx',nnel analysis. mctivation peaks characteristic of high intensity of at least one rich spectrum reference cem~ent associatfnd with the nature of the searched rare metal or of the rare metal itself as long as at has a rich spectrum are searched for, the count output of the pulses In relation to the energy is deduced from the identification of the peaks of said refercnce element and from the c- Intensity thereof, one, or a plurality of lines of said rare raetal are Iocatc'd and the contribution of said rare -metal to the counting rate at sai' ocatio!,i Is searched for, (57) Abri~gC Proc~d6 d'6valuation de la teneur en metal rare d'une formation g~ologique naturelle, et appareil. mettant en ceuvre ce proc~d6, dans lequel on 6met des neutrons dans La formation g~ologique, on recueille to rayonnement y pro venant des 616ments activ~s par les neutrons sur un dt~tectear fournissant des Impulsions de sortie representatives de l'6nergie da rayonnement y requ, on constitue un histogramme en 6nergie du rayonnement yi par analyse multi-canaux, on recherche dans l'histogramme les pics d'activation caract~ristiqaes de forte intensit6 d'aa moins an 616ment de r~f~rence dt spectre riche associ6 dans la nature aa m~taI rare recherch6 oa du m~tal rare luim~me dans la mesure o6t it a urt spectre riche, onl d~duit de, l'identirication des pics dudit 6l6ment do r~f~rence et de lear intensit6. le rendement de comptago des Impulsions en fonction de 1'6nergie, on rep~re l'emplacement d'une ou plusieurs rates dudit in6tal rare et on recherche audit emuplaccment la contribution dadit metal rate au taux de comptage.
A method and apparatus f or evaluating the rare metal content of a natural geological formation.
The present invention relates to a method for evaluating the rare metal content of a natural geological formation about a borehole and an apparatus for implementing such a method.
It finds a particularly important although not exclusive application in -the field of evaluating the gold content (Au 197) of ground during mining prospection. But i-c is also applicable to the search for other rare or prescious metals, such as silver or platinum.
Precious metal prospection is at the present time consuming and wearisome for it is essentially based on chemical analysis or washing of core samples takecn on the site from the geological layers assumed to be ritch in the desired material.
The invention aims at providing a method and apparatus answering better than those known heretofore the requirements of practice, particularly in that they mak~e it possible to determine the rare metal content of a natural geological formation in real time and reliably without requiring considerable handling, To this end, the invention proposes a method of evalu~ating the rare metal content of a natural geological formation about a borehole, which is characterized in that: Neutrons are emitted from inside the hole towards the geological formation for activat'klng the elements present in the formation, the Y radiation coming from the elements acti.vated in the formation are collected by a detector delivering output pulses representative of the energy of the Yf radiation received, an energy histogram is formed of the Y AL.LL'V radiation -by multichannel. anal~ysis, in the histogram the activation peaks are 2 sought for which are characteristic of high intensity of at least one rich spectrum reference element associated in nature with the desired rare metal, or the rare metal itself to the extent that it has a rich spec-um, from the identification of the peaks of said reference element or of the rare metal itself and 'f their intensity is derived the counting rate of the pulses as a function of the energy, and having located the position of one or more spectral rays characteristic of said rare metal in the histogram obtained, at said position the contribution of said rare metal is sought in the counting rate, the detector having been previously calibrated from detection of the activation radiation coming from a material having a known content of said desired rare metal, bombarded under experimental conditions close to the on site measurement conditions.
I" an advantageous process in accordance with the invention, the energy histogram of the T radiation coming from the activated element is formed by making a multichannel analysis of the T radiation collected with a channel width less than or equal to 3 KeV.
Recourse is also advantageously had to the following arrangements: the desired rare metal being gold and the characteristic spectral ray of activated gold being 412 KeV, the reference element is chosen from telluride, silver, zinc, palladium, lead, bismuth, tungsten, manganese and arsenic, the intensity of the neutron emission flow is modulated duxing the measurements while taking into account the desired rare metal and the previously determined physical conditions of the geological formation such as the hygrometry (or else relative humidity rate) or density, and the irradiation doses, the S delay before detection and the detection time are selected so as to obtaoin optimum measurements.
J 3 The invention also proposes an apparatus for detecting and evaluating the rare metal content of a natural geological formation for implementing the above method, characterized in that it comprises, in a movable unit in a probe hole, a neutron generator, actuatable by remote control, a Y radiation detector delivering output pulses representative of the energy of the Y radiations coming from the activated elements in the formation, a high energy resolution multi channel analyser connected to the detector and adapted for delivering a histogram of the detected energy spectrum, and computing means adapted for searching in the histogram for several characteristic activation peaks having a predetermined distribution (corresponding to at least one rich spectrum reference element associated in nature with the desired rare metal or corresponding to the rare metal itself to the extent that it has a rich spectrum), deriving from the identification of said peaks and from their intensity the counting rate of the pulses as a function of the energy qnd, from at least one characteristic spectral ray of said rare metal in the histogram obtained, calculating the contribution of said rare metal to the counting rate and restoring corresponding information.
In advantageous embodiments, recourse is further had to one and/or other of the following arrangements: The Y radiation detector is a semiconductor, advantageously germanium, detector, the multichannel analyser has a number of channels such that the elementary length of each channel, throughout the spectrum, is adapted to the resolution of the detector so as to obtain a very large number of points, the neutron emitter is fed by a very high S~ g^iL^ _I I -g i 4 voltage source (VHY) integrated in a case containing the emitter.
The invention will be better understood from reading the following description of a particular embodiment given by way of non limitative example. The description refers to the accomapnying drawings in which: Fig. 1 is a diagram showing in block form the different elements of an apparatus for implementing the method of the invention, Fig. 2 is an example of a histogram of the type obtained with the method of the invention, and Fig, 3 shows schematically an apparatus in accordance with the invention in a borehole.
The apparatus used in the present invention is first of all described with reference to Figb. 1 and 3 which show it schematically.
It comprises a module 1 in a case 2 shown with a chain dotted line in the Figs.
Module 1 is inserted then held in position by appropriate means, for example a winch 3, a cable 4 and centering means (not shown) for preventing pendular movements in a hole 5 in the natural geological formation 6 which it is desired to study. Hole 5 is for example a borehole drilled in the prospected ground.
The apparatus further comprises an analysis, computation and control device 7 situated on the surface.
The module contains a fi t or hig -speed neutron generator 8 having a source, for example with deuterium or tritium adapted for emitting towards the geological formation an intense flow 9 of high-speed neutrons for example of the order of 10 n/s with energies from 12 to 14 MeV. The high-speed neutrons emitted are thermalized in ground 6 and activate a part of the elements present in a volume of several tens of cubic centimeters about the hole and in the bombarded zone. The neutrons may 41, advantageously be slowed down so as to shift their Sspectrum towards the thermal range by inserting a i 1 L I i -L I I 1U paraffin or graphite screen 10 between the source and said zone. The high-speed neutron generator is fed by means 11 adapted for delivering the very high vc'tage required for its operation (higher than 100 Kv). So as to minimize the length of the connecting cables, these means may be advantageously incorporated in case 2 of the generator.
The activated elements, which form unstable radioactive isotopes, then disintegrate progressively to return to the stable state while emitting more particularly Y rays (reference 12 in Fig. 1).
These Y rays coming from ground 6 are collected by a detector 13 which forms part of module 1 and is situated close to generator 8. This detector 13 delivers output pulses representative of the energy of the Y radiation received and in a range going from a few KeV to a few Mev.
A semiconductor detector is advantageously, used for example lithium dop-d germanium or silicon.
Excellent resolution in x and Y spectrometry in a range of energy from a few 10 of KeV to about 10 MeV is obtained with this type of detector which has the further advantage of taking up little space (a few tens of cubic cm in volume). The detector is provided with a cryostat (not shown) for cooling the semiconductor.
The surface device 7 incl'udes a high energy resolution multichannel analyser 14 connected to detector 13 by a conductor forming part for example of cable 4.
The output pulses of the detector are transmitted to the high energy resolution multichannel analyser 14. It is desirable for the analyser to have a channel width less than 3 KeV, which makes a large number of channels possible. It delivers an energy histogram of the Y radiation received of the type shown in Fig. 2.
<L The analyser 14 is connected to comparison and computing means D J I p //VIM r/ -6 The values obtained are studied by these means giving finally the desired metal conOtent or a value representative of this value in accordance with the method of the invention, which will be described in detail further on.
Device 7 finally comprises restoration or display means 16 providing a result in real time and on the site and means 17, advantageously programmable, for supplying with power, monitoring and controlling the apparatus of the invention. These means include more particularly a remote control of the neutron generator which, among other things, makes it possible to modulate the intensity of the neutron flow during the measurements. Thus, the irradiation and detection times may be optimized with respect to each other as a function of the desired metal (taking into account the periods of its activation products in particular. and of the physical conditions (hygrometry, density, etc of the geological formation ,The measurements made are thus made quantitatively more significant.
Means 15, 16 and 7 are formed in a way known per se, By way of non limitative example, one possible example is given of the operating mode of an apparatus lowered into a probehole for evaluating the gold content of a geological formation at several depths. For determining the numerical values, the half period of AU 198 must be taken into account, which is 2.8 days. The apparatus is lowered to a first depth 5nd emits for a first prede~termined time; it is then lowered to a second depth and emits for a second predetermined time and so on. Once the ground has been activated at different points for known times, the apparatus is then raised in steps, operating this time solely as a detector. It is placed at the points of neutron emission during lowering, for previously optimized times and after lapses of time for decay of the activated layers chosen so as to obtain 7 significant results with measurements extending over reasonably short periods in time so as to be compatible with on site operations.
Another operating mode consists in lowering the apparatus in a continuous movement while increasing the intensity of the neutron flow progressively during lowering.
Raising may on the other hand take place in steps solely for detection purposes.
Identification of the desired rare metal is more precisely described hereafter.
From the histogram and in real time, the activation peaks are sought of one or more rich spectrum reference elements associated in nature with the desired rare metal or of the rare metal itself to the extent where its activation product has a rich spectrum.
The reference elements or the rare metal itself if possible, and advantageously, will have to comply with the following three criteria: presence of several peaks of the activated element in a fairly wide energy range, intensity of these peaks and isolation of these peaks in the spectrum, which makes it possible to differenciate them relatively easily from the background noise due more particularly to Compton photons, presence of these peaks close to peaks of the element which it is desired to identify if necessary.
Identification of the peaks or of the reference elements or of the activated rare metal itself makes it possible to calibrate the axis of the histogram on which are plotted the energies of the activation peaks of the whole of the radiation received by the detector (axis of the Xs in Fig. 2).
Then the position of one or more of 'the characteristic spectral rays of the desired rare metal is recorded. By way of example, the characteristic spectral ray of the activ.ated isotope AU 198 of natural gold Au 8- 197 is situated at about 412 KeV. Since the spectrum of activated gold is poor, the following reference elements (and their activation peaks) may be advantageously used: Mn 56 (846, Key, 1810 Key, 2110 Key), Ag 110 m (657 Key), Ag 108 m (434 Kev), As 75 (558 Key), As 76 (666 Key),..
Once the spectral ray of the rare imetal has been identified, the number of pulses generated by the unstable isotope during its decay must be evaluated quantitatively so as to derive therefrom the rare metal content of the geological formation. This is achieved by previous calibration of the axis of the Ys of the histogram,. giving For example shocks per second, by calibrating the detector.
For a known amount of high-speed neutrons emitted into the ground, the amount of photons received in return, for a given spectral ray, will depend on three parameters: the absorption due to the medium, the efficiency of the detector which varies with the energy of the photons, the "rancie pf vision" of the detector in the borehole which makes it possible to take into account the factors depending on the geometry existing between the detector and the material.
Determination of these three paramete-s, which it was first of all necessary to identify clearly, is required for putting into practice the apparatu~s and method of the invention. Now, the absorption of activation photons due to the medium is a parameter which has always seemed impossible to determine simply during on site measurements.
In a novel and inventive way, the inventor had the idea of simply deriving this rpinfrom the pure spectrum of the reference element with which the decayed spectrum of the same element obtained on the histogram is compared, Thus, the invention has greatly facilitated the on site determination of absorption until now difficult
L
-9 to evaluate. Since the respective values of each spectral ray should be proportional to those of the pure spectrum, the absorption due to the medium can be deduced therefrom for the different energies concerned, in particular for those of that one or of those spectral rays of the desired rare element or those surrounding or close to a characteristic spectral ray thereof and then by extrapolating that of this latter, The effeciency of the detector is further known which is determined during previous calibration of the apparatus. It varies as a function of the energies received and has been introduced initially, for example, into the computer.
Under these conditions, calibration of the apparatus is reduced to the determination of a single parameter or coefficient which amounts to the "range of vision" of the detector in the borehole.
This single coefficient is obtained by measuring, under experimental conditions as real as possible, a material whose content of the desired rare metal is known.
As is evident, and as it follows already from what has gone before, the present invention is in no wise limited to those of its modes of application and embodiments which have been more especially considered; it may in particular be used for determining the content of any other type of rare metal than gold, silver or platinum and which is met with in nature.
S,
I .j i r
Claims (5)
- 3. The method according to claim 1, character- ized in that the searched rare metal being gold and the characteristic spectral ray of activated gold being 412 KeY, the reference element is chosen from telluride, silver, zinc, palladium, lead, bismuth, tungsten, manganese and arsenic.
- 4. The method according to claim 1, character- ized in that the intensity of the neutron emission flow is mnoOulated durnij the measurements while tak-ng into j! account the searched rare metal characteristics and the previously determined physical conditions of the geological formation, ano the irradiation doses, tne delay before detection and the detection time are selected so as to obtain cptimum measurements. An apparatus for detecting and evaluating the rare metal content of a natural geologcal formation (6) comprising in a unit movable within a probe hol, a neutron *enerator a If radiation (12) detector (13) delivering output pulses representative of the energy of the r radiations coming from the a:ctivatedAelements in the formation. and further a high energy resolution multi channel analyser (14) connected to the detector (13) and adapted for delivering a histogram of the detected energy spectrum, characterized in that the generator is a high e, -t "euir Qs ger.eratar remcn t roll. ad in that the apparatus comprises in addition computing means 16 17) adapted for searching in the histogram for several characteristic activation peaks having a pre- determined distribution corresponding to at least cne rich spectrum' reference element associated in nature with the searched rare n;etal, deducting from the iden- tification of said peaks and from their intensity the counting rate Of the pulses as a function of the energy Sand, from at least one characteristAic spectral ray o'f y said rare metal in the histogram obtained, calculating ig X f s) 12 the contribution of said rare metal to the counting rate and restituting corresponding information, calibration of said apparatus consisting in the determination of a parameter of the detector obtained by measuring under experimental conditions a material whose content of the desired rare metal is known.
- 6. The apparatus according I claim 5, characterized in that the y radiation detector (13) is a semiconductor, for example a germanium detector,
- 7. The apparatus as claimed in any one of claims 5 and 6, characterized in that the multichannel analyser (14) has a number of channels such that the elementary length of each channel, throughout the spectrum, is adapted to the high S, resolution of the detector.
- 8. The apparatus as claimed in any one of the cl3ims 6 and 7, characterized in that the emitter of neutrons is fed by a very high voltage source (11) integrated in a case containing the emitter. DATED this 31st day of May, 1990. COMPAGNIE GENERALE DES MATIERES NUCLEAIRES WATERMARK PATENT TRADEMARK ATTORNEYS, "The Atrium", 290 Burwood Road Hawthorn, Victora, 3122 AUSTRALIA LCG/KJS:BB (JJC4/3) I i i I i I" 13 ABSTRACT OF THE DISCLOSURE A method is provided for evaluating the rare metal content of a natural geological formation and an apparatus for implementing this method, in which neutrons are emitted into the geological formation, the Y radiation coming from the elements activated by the neutrons are collected by a detector delivering output pulses representative of the energy of the r radiation received, an energy histogram of the Y radiation is formed by multichannel analysis, the activation peaks are Ljught in the histogram which are characteristic of high intensity of at least one rich spectrum reference element associated in nature with the desired rare metal or of the rare metal itself to the extent that it has a rich spectrum, and from the identification of the peaks of said reference element and from their intensity is deduced the counting rate of the pulses as a function of the energy, the position of one or more spectral rays of said rare metal is located and at said position the contribution of said rare metaJ, in the counting rate is sought. I,, *r
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8705281A FR2614111B1 (en) | 1987-04-14 | 1987-04-14 | METHOD AND APPARATUS FOR EVALUATING THE RARE METAL CONTENT OF A NATURAL GEOLOGICAL FORMATION |
| FR8705281 | 1987-04-14 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU1623988A AU1623988A (en) | 1988-11-04 |
| AU600579B2 true AU600579B2 (en) | 1990-08-16 |
Family
ID=9350102
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU16239/88A Ceased AU600579B2 (en) | 1987-04-14 | 1988-04-14 | Method and apparatus for evaluating the rare metal content of a natural geological formation |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0296894A3 (en) |
| AU (1) | AU600579B2 (en) |
| BR (1) | BR8806897A (en) |
| FR (1) | FR2614111B1 (en) |
| WO (1) | WO1988008143A2 (en) |
| ZA (1) | ZA882636B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10114130B2 (en) | 2016-11-29 | 2018-10-30 | Battelle Energy Alliance, Llc | Detectors for use with particle generators and related assemblies, systems and methods |
| CN107490591A (en) * | 2017-04-19 | 2017-12-19 | 安徽华脉科技发展有限公司 | A kind of heavy metal in soil content detection device |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1396642A (en) * | 1973-03-29 | 1975-06-04 | Texaco Development Corp | Borehole gamma ray spectroscopy |
| US4507553A (en) * | 1982-09-01 | 1985-03-26 | Dresser Industries, Inc. | Method and apparatus for identifying vanadium in earth formations |
| GB2173298A (en) * | 1985-04-02 | 1986-10-08 | Commissariat Energie Atomique | Spectrometric gamma diagraphy system for the determination of the geological parameters of a rock |
-
1987
- 1987-04-14 FR FR8705281A patent/FR2614111B1/en not_active Expired
-
1988
- 1988-04-14 AU AU16239/88A patent/AU600579B2/en not_active Ceased
- 1988-04-14 ZA ZA882636A patent/ZA882636B/en unknown
- 1988-04-14 WO PCT/FR1988/000184 patent/WO1988008143A2/en unknown
- 1988-04-14 EP EP88400905A patent/EP0296894A3/en not_active Withdrawn
- 1988-04-14 BR BR888806897A patent/BR8806897A/en unknown
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1396642A (en) * | 1973-03-29 | 1975-06-04 | Texaco Development Corp | Borehole gamma ray spectroscopy |
| US4507553A (en) * | 1982-09-01 | 1985-03-26 | Dresser Industries, Inc. | Method and apparatus for identifying vanadium in earth formations |
| GB2173298A (en) * | 1985-04-02 | 1986-10-08 | Commissariat Energie Atomique | Spectrometric gamma diagraphy system for the determination of the geological parameters of a rock |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2614111B1 (en) | 1989-07-13 |
| ZA882636B (en) | 1989-07-26 |
| BR8806897A (en) | 1989-10-17 |
| EP0296894A3 (en) | 1989-01-11 |
| FR2614111A1 (en) | 1988-10-21 |
| AU1623988A (en) | 1988-11-04 |
| WO1988008143A2 (en) | 1988-10-20 |
| WO1988008143A3 (en) | 1988-12-15 |
| EP0296894A2 (en) | 1988-12-28 |
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