CN114264681A - Method and system for analyzing gold ore grade - Google Patents
Method and system for analyzing gold ore grade Download PDFInfo
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Abstract
The invention discloses a method and a system for analyzing gold ore grade. The method comprises the following steps: (1) activating the gold ore to be tested by using neutrons so as to ensure that the neutrons in the gold ore to be tested197Activation of Au to198Au；(2)198Generation of Au into beta‑Decay to form198Hg, test198The intensity of gamma rays emitted by Au decay so as to obtain the gold grade of the gold ore to be detected. The method uses the slow-release gamma as197The marker of the existence of Au can be accumulated and counted under a long time scale (minutes, hours and days) according to actual requirements, so that better measurement statistics can be obtained, and the measurement precision can be ensured. Therefore, the method is more reliable, has high measurement precision, is easier to realize industrial production, and can effectively solve the problems of slower processing speed and XRF (X-ray fluorescence) frequency division of the traditional pyrometallurgical methodThe precipitation being restricted to the surface of the ore and the photon-activation process being limited by197The homogeneous and heterogeneous energy state of Au has shorter half-life period, so that higher analysis precision cannot be obtained.
Description
Technical Field
The invention belongs to the technical field of nuclear, and particularly relates to a method and a system for analyzing gold ore grade.
Background
In the mining of gold ores, the trend of ore veins and the mining value need to be determined frequently according to the result of the grade analysis of the mined gold ores. Currently, the grade of gold ore is mainly analyzed by a fire gold testing method, an X-ray fluorescence analysis (XRF) method and a photon activation method. Wherein:
the fire-testing method mainly separates pure gold from the ore by a series of physical and chemical means, and calculates the gold grade by the mass before and after weighing treatment. The method comprises the following main operation steps: crushing, material mixing, melting, ash blowing, separating, secondary melting, separating and the like. The method is complex to operate, needs professional personnel to operate, has low automation degree, and cannot meet the passing rate requirement of mass measurement.
X-ray fluorescence (XRF) analysis uses X-rays to irradiate ores, so that atoms of the ores are excited, quantitative measurement of element content is realized by measuring the strength of characteristic X-rays released in the process of deactivation, but the analysis range is small, so that the element content on the surface layer of the ores can only be effectively analyzed, automatic detection can be realized, and credible analysis of the whole gold grade of the ores is difficult.
The photon activation method uses photons with higher energy and stronger penetrability to irradiate a sample, can realize the analysis of the deep layer of the ore, and the photon energy at the moment can excite197And (4) enabling the Au atomic nucleus to reach a homogeneous and heterogeneous energy state with a half-life period of 7s, and calculating the grade of the gold by measuring the intensity of characteristic rays released by the energy state in a deactivative mode. To achieve high analytical accuracy, it is desirable that the activation process produce more and better characteristic radiation, but limited by197The half-life of Au homogeneous and heterogeneous energy state is short, the characteristic ray intensity cannot be obviously enhanced by longer irradiation or measurement time (reaching 95 percent of the maximum intensity by 30s irradiation), and the analysis precision cannot be further improved.
Therefore, the method of analyzing the grade of gold ore still remains to be further modified.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. To this end, it is an object of the present invention to provide a method and system for analyzing gold ore grade to solve the problems of the slow processing speed of the conventional pyrometallurgical method, the limited XRF analysis to the surface of the ore and the photon activation method subject to the limitations197Homogeneity of AuThe half-life of the heterostate is short, so that higher analysis precision cannot be obtained.
In one aspect of the invention, a method of analyzing gold ore grade is provided. According to an embodiment of the invention, the method comprises:
(1) activating the gold ore to be tested by using neutrons so as to ensure that the neutrons in the gold ore to be tested197Activation of Au to198Au；
(2)198Generation of Au into beta-Decay to form198Hg, test198The intensity of gamma rays emitted by Au decay so as to obtain the gold grade of the gold ore to be detected.
The inventor finds that the neutron can be used for analyzing gold element, and the analysis mechanism is shown as the following formula:
197au captures neutrons (the neutrons are represented by n) and reacts with (n, gamma) to form198Au, which continues to generate beta after the prompt gamma is emitted-Decay and form198Hg, while emitting delayed gamma, whereas delayed gamma is caused by197The Au produced after absorbing neutrons can use delayed gamma as197And analyzing the content of the gold element by analyzing the intensity of the marker of the existence of Au, thereby realizing the analysis of the grade of the gold ore. Due to the fact that198The long half-life of Au (2.6 days) is limited relative to photon activation methods197The half-life of Au homoenergetic state is shorter (7s) so that higher analysis precision cannot be obtained, and the slow-release gamma is used as197The marker of the existence of Au can be accumulated and counted under a long time scale (minutes, hours and days) according to actual requirements, so that better measurement statistics can be obtained, and the measurement precision can be ensured. Therefore, the method for analyzing the grade of the gold ore in the embodiment of the invention is more reliable, has high measurement precision and is easier to realize industrial production.
According to embodiments of the present inventionTesting by high purity germanium spectrometer198The intensity of gamma rays emitted by the decay of Au, and the mass ratio of the gold to be detected is
Wherein M isAuIs composed of197Relative atomic mass of Au; n'0In the gold ore sample to be tested197The number of Au atoms; n is a radical ofAIs an Avogastron constant; m is the quality of the gold ore sample to be detected; and Grade is the mass ratio of gold in the gold ore sample to be detected.
According to the embodiment of the invention, the gold ore sample to be detected197N 'of Au atom number'0The formula is as follows:
and
wherein N' is Au characteristic gamma 411keV net count detected by a germanium detector in a high-purity germanium spectrometer; σ' is197Au neutron capture reaction cross section; lambda' is an activating nucleus198The Au decay constant; epsilon'p-sThe detection efficiency of the germanium detector in the high-purity germanium spectrometer on the peak source of the 411keV gamma ray is obtained; epsilon'bIs composed of198Au produces a branch ratio of 411keV gamma rays; n is a characteristic gamma net count generated after nuclide of a reference material detected by a germanium detector in a high-purity germanium spectrometer is activated; n is a radical of0Is the atomic number of the species of the reference material;
is the neutron fluence rate; sigma is a nuclide neutron capture reaction section of a reference material; λ is the decay constant of the reference material after nuclide activation; t is tirrIs the irradiation duration; t is tcoolThe time interval between the end of irradiation and the start of measurement; t is tmMeasuring time length for a high-purity germanium spectrometer; epsilonp-sThe peak source detection efficiency of characteristic gamma rays generated after a germanium detector in a high-purity germanium spectrometer activates nuclides of a reference material is obtained; epsilonbNuclide activity as reference materialThe branch ratio of the gamma rays generated after the conversion.
Based on the same inventive concept, in yet another aspect of the present invention, a system for analyzing grade of gold ore is provided. According to an embodiment of the invention, the system comprises:
the activation system comprises an electron accelerator, an electron conversion target, a neutron conversion body, an irradiation cavity and a neutron moderating body, wherein the electron accelerator is suitable for providing accelerated electrons and bombarding the electron conversion target by the accelerated electrons; the neutron conversion body defines a conversion cavity, the electron conversion target is arranged in the neutron conversion cavity and is suitable for generating X rays under the bombardment of the accelerated electrons, and the neutron conversion body is suitable for converting the X rays into neutrons; shine the chamber and establish one side of neutron conversion body and for enclosed construction, neutron moderation body is followed the circumference in irradiation chamber is arranged, neutron moderation body is suitable for realizing the gold ore sample business turn over that awaits measuring shine the chamber with right the neutron moderation, it is suitable for holding to shine the chamber the gold ore sample that awaits measuring and utilize moderation neutron right the gold ore sample that awaits measuring activates, makes in the gold ore sample that awaits measuring197Conversion of Au to198Au；
The high-purity germanium spectrometer comprises a germanium detector, an energy spectrometer, a refrigerating device and a computer, wherein the germanium detector is suitable for collecting gamma rays emitted by the gold ore sample to be detected, the energy spectrometer is suitable for converting gamma ray signals detected by the germanium detector into an energy spectrum, the computer is suitable for analyzing the energy spectrum to obtain the content of gold in the gold ore sample to be detected, and the refrigerating device is suitable for providing a low-temperature environment for germanium crystals in the germanium detector.
The system for analyzing the grade of the gold ore in the embodiment of the invention at least has the following beneficial effects: a. the electron accelerator is used for preparing the photon source, has good stability, can provide strong neutron beam current due to large flow intensity, has small size, is suitable for industrial production and is compared with the isotope source and the neutron source used in the existing laboratoryCompared with neutron sources such as a generator, a reactor, a spallation source and the like, the neutron source is more practical and reliable, has high neutron yield and small occupied area, can be used for industrial field, and realizes accurate and efficient analysis of gold ore grade. b. When the neutrons are adopted to activate the gold ore to be tested, the neutrons need a slower speed to effectively react with the gold, if the neutrons have a faster speed, the reaction capability with the gold is poorer, the reaction efficiency is low, and the test sensitivity is poorer. c. The gold ore to be tested is activated in an activation system in advance, and then the activated gold ore to be tested is tested by adopting a high-purity germanium spectrometer because197The half-life of the prompt gamma emitted after the Au captures the neutron is extremely short, so that the sample can be transferred in the process197Transient gamma emitted by Au activation is completely eliminated, so that the interference of the transient gamma to the slow-emitting gamma with a longer half-life period is avoided, and the accuracy and the reliability of the test structure are ensured. d. When the system is used for analyzing the grade of gold ore, the system is characterized in that198The long half-life of Au (2.6 days) is limited relative to photon activation methods197The half-life of Au homogeneous and heterogeneous energy state is shorter (7s) so that higher analysis precision cannot be obtained, and the slow-release gamma can be used as197The marker of the existence of Au can be accumulated and counted under a long time scale (minutes, hours and days) according to actual requirements, so that better measurement statistics can be obtained, and the measurement precision can be ensured. d. The system also has the advantages of simple structure, high measurement precision and easy realization of industrial production.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a flow chart of a method of analyzing gold ore grade according to one embodiment of the present invention.
FIG. 2 is a schematic diagram of a further embodiment of the present invention198Au decay scheme.
FIG. 3 is a flow chart of the activation of a gold ore to be tested according to one embodiment of the present invention.
FIG. 4 is a spectrum of optical neutrons produced by a 9MeV electron accelerator, in accordance with one embodiment of the present invention.
FIG. 5 is a graph of a neutron spectrum and its fluence rate inside an irradiation chamber according to one embodiment of the invention.
FIG. 6 is a graph of cadmium metal in accordance with one embodiment of the present invention113Neutron absorption cross-sectional view of Cd.
FIG. 7 is a block diagram of an embodiment of the present invention197Au(n，γ)198Reaction cross section of Au.
Fig. 8 is a block diagram of a system for analyzing gold ore grade according to one embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
In the description of the present invention, it is to be understood that the terms "thickness", "upper", "lower", "inner", "outer", "circumferential", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplification of description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
In one aspect of the invention, a method of analyzing gold ore grade is provided. According to an embodiment of the invention, as shown with reference to fig. 1, the method comprises: (1) activating the gold ore to be tested by using neutrons so as to ensure that the neutrons in the gold ore to be tested197Activation of Au to198Au；(2)198Generation of Au into beta-Decay to form198Hg, test198The intensity of gamma rays emitted by Hg so as to obtain the gold grade of the gold ore to be detected. The inventor finds that the neutron can be used for analyzing gold element, and the analysis mechanism is shown as the following formula:
197au captures neutrons (the neutrons are represented by n) and reacts with (n, gamma) to form198Au, which continues to generate beta after the prompt gamma is emitted-Decay and form198Hg, while emitting delayed gamma, whereas delayed gamma is caused by197The Au produced after absorbing neutrons can use delayed gamma as197And analyzing the content of the gold element by analyzing the intensity of the marker of the existence of Au, thereby realizing the analysis of the grade of the gold ore. Due to the fact that198The long half-life of Au (2.6 days) is limited relative to photon activation methods197The half-life of Au homoenergetic state is shorter (7s) so that higher analysis precision cannot be obtained, and the slow-release gamma is used as197The markers of the presence or absence of Au can be accumulated and counted under a long time scale (minutes, hours and days) according to actual needs to obtain better measurement statistics, so that the measurement accuracy can be ensured, wherein FIG. 2 shows198Decay rule of AuThe energy of the most dominant gamma-ray generated by its de-excitation is 411 keV. Therefore, the method for analyzing the grade of the gold ore in the embodiment of the invention is more reliable, has high measurement precision and is easier to realize industrial production. It should be noted that the (n, γ) reaction in the present invention refers to a nuclear system of excited state formed after the neutron is captured by the atomic nucleus, and the radiative decay of one or several γ photons in a very short time is returned to the ground state.
The method for analyzing grade of gold ore according to the above embodiment of the present invention will be described in detail with reference to fig. 1 to 7.
(1) Activating the gold ore to be detected by using neutrons, and carrying out the activation on the gold ore to be detected197Activation of Au to198Au
According to an embodiment of the present invention, referring to fig. 3, the activation of the gold ore to be tested may include the following steps:
(1-1) generating accelerated electrons using an electron accelerator
According to the embodiment of the invention, the electron accelerator can be utilized to provide stable high-current electrons, and further provide stable high-current neutrons. The inventor finds that the electron accelerator has very good stability, the flow intensity can be very large, very strong neutron beam current can be provided, the size of the electron accelerator is very small, the electron accelerator is used in industrial production level, compared with the existing neutron sources (not suitable for industrial use) such as laboratory-level isotope sources, neutron generators, reactors, spallation sources and the like, the electron accelerator provided by the invention is used for providing stable high-flow neutrons, the neutron source is more practical and reliable, the neutron yield is high, the occupied area is small, the electron accelerator can be used in industrial sites, and the accurate and efficient analysis of gold ore grade is realized.
According to the embodiment of the invention, the accelerated electron energy generated by the electron accelerator can be not higher than 10MeV, and the inventor finds that if the accelerated electron energy exceeds the range, air is strongly activated to generate radioactive hazards and affect the health of surrounding people, and the invention is more beneficial to safety protection by controlling the accelerated electron energy to be not more than 10 MeV.
(1-2) bombarding the electron conversion target with accelerated electrons to obtain X-rays
According to the embodiment of the present invention, the material of the electron conversion target is not particularly limited as long as it can generate high-energy X-rays under the accelerated electron bombardment, and those skilled in the art can flexibly select the material according to the actual requirement, for example, the electron conversion target may be a tungsten target.
(1-3) converting X-ray into neutron by neutron converter
According to an embodiment of the present invention, a neutron converter may be disposed around the electron conversion target, so that the X-rays are converted into neutrons here, and the original energy spectrum of the neutrons may be understood with reference to fig. 4, where fig. 4 is an energy spectrum of photoneutrons generated by a 9MeV electron accelerator. Preferably, the neutron conversion material may be beryllium or heavy water, and the inventors have found that the energy of X-rays is not so high that photonuclear reactions with low-threshold nuclides are required to generate neutrons, and that the electron accelerator chosen in the present invention is not so high that beryllium or heavy water is more favorable as the neutron converter to convert X-rays to neutrons. The specific arrangement of the neutron conversion body is not particularly limited, and a person skilled in the art can select the arrangement according to actual needs, for example, a conversion cavity can be defined in the neutron conversion body, and the conversion cavity can be filled with a neutron conversion material (such as water or beryllium) so that the electron conversion target is located in the neutron conversion material. For another example, when heavy water is selected as the neutron conversion material, the neutron conversion material can be packaged by an aluminum can, so that the heavy water in the aluminum can generates neutrons, wherein the aluminum can is almost transparent to the neutrons; when beryllium is selected as the neutron conversion material, beryllium packaging can be directly adopted, even if the neutron moderating body is of an integrated structure.
(1-4) converting neutrons into moderated neutrons by means of a neutron moderator
According to the embodiment of the invention, neutrons obtained by converting X-rays by using the neutron converter are fast neutrons, and need to be moderated. The inventor finds that neutrons can effectively react with gold only at a slow speed, if the neutrons have a fast speed, the reaction capacity of the neutrons with gold is poor, the reaction efficiency is low, the test sensitivity is poor, the moderation of the neutrons is more favorable for improving the reaction efficiency and effect of the neutrons and the gold, and the test sensitivity and the accuracy and reliability of the test result are improved. It should be noted that although the neutron conversion body can play a role in moderating, a better moderating effect is still from the neutron moderating body, preferably, the neutron moderating body can be arranged along the circumferential direction of the sample to be measured, and more preferably, an irradiation cavity can be formed in the middle of the neutron moderating body, so that the gold ore to be measured is placed in the irradiation cavity for activation, thereby achieving a better moderating effect, and ensuring that neutrons irradiated onto the gold ore to be measured through the neutron moderating body are all moderated neutrons.
According to embodiments of the present invention, a hydrogen-containing material may be selected as the neutron moderator. The inventor finds that hydrogen is a good neutron moderating material, the mass of the hydrogen is almost the same as that of neutrons, and when neutrons collide with protons, the energy of the neutrons is more easily consumed to be moderated, so that a remarkable neutron moderating effect is achieved. It is understood that the kind of the hydrogen-containing material in the present invention is not particularly limited, and those skilled in the art can flexibly select the material according to the actual needs, for example, a material with a high hydrogen content may be preferred as the neutron moderating body, such as water, polyethylene, polypropylene, or paraffin, so as to achieve a better moderating effect.
According to the embodiment of the invention, an irradiation cavity can be arranged in the middle of a neutron moderating body, and the gold ore to be detected is fed into the irradiation cavity through a conveyor belt, wherein the neutron moderating body can move, be opened and closed, the gold ore to be detected enters the irradiation cavity when the movable neutron moderating body is in an opened state, and then the movable neutron moderating body is closed again, so that a closed neutron field appears in the irradiation cavity, and a higher neutron fluence rate is obtained. It should be noted that, when the gold ore to be detected is subjected to sample injection, the electron accelerator is not operated. It should be noted that the position and size of the irradiation chamber have a significant influence on the intensity of neutrons, and the irradiation chamber may be preferably provided in a region where the intensity of the neutron fluence rate is the strongest, for example, the irradiation chamber may be provided on the side of the neutron converter corresponding to the direction in which the accelerated electrons strike the electron conversion target, and further, for example, the optimum neutron fluence rate and energy spectrum inside the irradiation chamber may be as shown in fig. 5.
According to the embodiment of the invention, the neutron moderating body and the neutron conversion body can be directly or indirectly contacted to realize the conversion and moderation of neutrons, for example, when heavy water is selected as a neutron conversion material, an aluminum can is adopted for packaging, the aluminum is almost transparent to neutrons, neutrons generated in the heavy water can penetrate through the aluminum can to enter the neutron moderating body to form moderated neutrons, and the moderated neutrons enter the irradiation cavity; in addition, the structure of the irradiation chamber is not particularly limited, and those skilled in the art can flexibly select the irradiation chamber according to actual conditions, for example, the irradiation chamber may have a hexahedral structure, and the peripheral wall of the hexahedral structure may be the neutron moderator material.
And (1-5) irradiating the gold ore to be detected with moderated neutrons for activation.
According to the embodiment of the invention, the irradiation time of irradiating the gold ore to be detected by using moderated neutrons can be not less than 1s, and the inventor finds that for gold, if the irradiation time is too short, the generated gold ore is subjected to irradiation treatment198The quantity of Au is small, the measured gamma rays are small, the measurement precision is reduced, the measurement accuracy is influenced, the irradiation time is prolonged, and the measurement accuracy is improved197The activation effect of Au is better, and the irradiation time is controlled to be not less than 1s in the invention, so that the gold ore sample to be detected can be obtained197Sufficient Au nuclides are generated through (n, gamma) reaction198The Au nucleus, in turn, can further ensure the measurement accuracy and the reliability of the measurement result, but it should be noted that if the irradiation time is too long, the measurement efficiency will be too low, and those skilled in the art can flexibly select within the above irradiation time range.
According to the embodiment of the invention, the gold ore to be detected can be irradiated by the moderated neutrons for activation in the presence of the reference material, wherein the reference material can preferably move together with the gold ore to be detected, namely, the reference material is conveyed into/out of the irradiation cavity together with the gold ore to be detected, and the activation and detection process of the whole gold ore to be detected is accompanied, the inventor finds that the stability of an accelerator, the size of the sample to be detected, the type of the material and the like can influence the irradiation during detectionA neutron field in the chamber, thereby enabling197The analytical sensitivity of Au also changed, and thus the analysis was carried out198In order to solve the problem that the content of gold element is analyzed by Au gamma ray, errors can occur, one or more reference materials can be placed in the irradiation cavity to detect the inconsistency of the neutron irradiation field, and systematic errors are eliminated, wherein the reference materials enter, irradiate and leave the irradiation cavity along with the gold ore sample to be detected, namely, the irradiation time of the reference sheet and the sample is completely the same. Further, in order to better eliminate the systematic error caused by the above interference factors, when selecting the reference material, it is preferable to make the half-life of the generated radionuclide when the element in the reference material is irradiated by neutron and the half-life of the generated radionuclide198The half-life of Au is not greatly different, and the energy of the generated gamma ray is also not greatly different, therefore, the material of the reference material can be preferably selected from at least one of Eu, In, Mn, Ir, Re, W, La, Sb, Dy, As, Ga, Yb and Br, wherein the characteristics of the reference material In the material range are shown In Table 1, and the reference material is selected to be more beneficial to reducing system errors. Furthermore, one or more reference materials and/or one or more reference materials made of materials can be arranged in the circumferential direction of the gold ore to be detected, so that systematic errors can be eliminated; more preferably, In order to better monitor the irradiation condition of the gold ore sample to be measured, a plurality of reference materials of various materials can be used, for example, Eu, In and the like can be placed at the upper, lower, left and right positions of the sample to be irradiated. The form of the reference material is not particularly limited, and may be selected by those skilled in the art according to actual needs, and may be, for example, a sheet or a ring.
TABLE 1 Properties of different reference materials
According to the embodiment of the invention, after the irradiation is finished, the activated gold ore to be detected can be cooled. The inventors have found that irradiated samples will contain a variety of radioactivity, among othersSome from the radioactivity of the gold element and the reference material and some from the radioactivity of the matrix element in the sample, the sample needs to be cooled for a period of time, so that the part with shorter half-life period in the sample decays, thereby reducing the background count from the sample during system measurement, realizing better cost ratio and obtaining better statistics on the premise of the maximum passing rate. The half-life of the product nuclide of the common associated elements of the gold ore after neutron irradiation is shown in table 2, wherein O, Al, Fe, Mg, Cu and S release gamma in the half-life of several seconds to several minutes, and contribute to the main background gamma. It should be noted that, for different gold ores to be measured, the cooling time may be flexibly selected according to actual conditions, for example, the composition and content of elements other than gold in each gold ore sample to be measured may be different, and the cooling time needs to be determined by combining general analysis and special analysis, so long as the interference count rate of the elements after cooling is reduced to a certain degree, specifically, the interference count rate of the elements after cooling may be reduced to a certain degree198The increase of the cost ratio is at least two orders of magnitude on the premise that the activity of Au is basically unchanged (only reduced by about 1%); for another example, according to a specific example of the present invention, in combination with the gold ore associated elements in table 2, the cooling time may be set to 60min, in which case the background of the contribution of the associated elements may be reduced by more than two orders of magnitude, which may be at the level of the associated elements198The accuracy and reliability of the test result can be further improved by improving the cost ratio by at least two orders of magnitude on the premise that the activity of Au is basically unchanged (only reduced by about 1%).
TABLE 2 information of abundance, thermal neutron activation cross section, etc. of common associated elements in gold mine
According to the embodiment of the invention, in order to improve the cost ratio (the relation between the signal and the background) when gold is analyzed, the gamma counting rates of other elements in the ore need to be reduced, so that thermal neutrons in the moderated neutrons can be removed in advance, and the obtained moderated neutrons are used for irradiating the gold ore to be detected. The inventors have found that all elements can react with thermal neutrons, if thermal neutrons are usedThe gold is difficult to obtain obvious advantages when being analyzed, because the content of the gold in the ore is only ppm and belongs to elements with very trace content, if thermal neutron irradiation is adopted, the intensity of gamma rays released by the gold is far less than that of other elements, the resonance of the gold is 4.9eV and is obviously different from that of other elements, and based on the fact that thermal neutrons in moderated neutrons can be removed by adopting neutrons near the specific energy, the intensity of other elements is not obvious, and the gold still keeps high sensitivity; further, by removing thermal neutrons, because the radioactive signal of the interference element is depressed, on the premise that the system throughput is limited, the signal-to-noise ratio is greatly improved, the analysis speed is accelerated, and the total radioactivity level of the gold ore sample to be detected in the measurement process is reduced, which is very important for online use. Further, gadolinium, cadmium, or other absorbers may be utilized to filter out thermal neutrons. Specifically, the thermal neutron absorber material may be provided as a thermal neutron filter, specifically, the thermal neutron filter may be provided on the inner wall of the irradiation cavity, the thermal neutron filter may suppress the thermal neutron fluence rate in the irradiation cavity, so as to avoid (n, γ) reaction between the thermal neutrons and the element in the gold ore to be measured, the thermal neutron filter may be formed by selecting metal gadolinium and/or metal cadmium, and the thermal neutron filter may be mainly characterized by being capable of strongly absorbing the thermal neutrons, but having a small absorption cross section for neutrons of about 4.9eV (where the absorption cross section is small) (where the absorption cross section is about 4.9 eV)113Neutron absorption cross section of Cd see fig. 6) to ensure197Au can be obtained higher through resonance reaction198Au yield, wherein FIG. 7 shows197Au(n，γ)198Reaction cross section of Au.
According to the embodiment of the invention, a metal gadolinium sheet and/or a metal cadmium sheet can be used as a thermal neutron filter, wherein the thickness of the sheet-shaped thermal neutron filter can be 0.8-1.2 mm, and preferably can be not less than 1mm, the inventor finds that the larger the thickness of the thermal neutron filter layer is, the better the absorption capacity for thermal neutrons is for the same type of neutron filter material, and through simulation calculation, when the cadmium sheet with the thickness of 1mm is used as the thermal neutron filter, the intensity of the thermal neutrons will be reduced by about 150 times, and the reduction of the intensity of resonance neutrons of 4.9eV is negligible. In this case, the signal of the species that produce interfering radioactivity due to thermal neutron absorption is reduced by more than 2 orders of magnitude (simulation calculation: 147 times), while the signal of gold element is reduced by only 60% (simulation result: 38.6%), and the cost ratio is thus improved by nearly 2 orders of magnitude (simulation calculation: 56 times). In practice, this cost ratio improves even more when the thickness of the cadmium sheet is changed to be thicker, or a gadolinium sheet with better thermal neutron absorption (0.8 mm thickness reduces the signal of interfering radioactive species by more than 2 orders of magnitude).
According to the embodiment of the invention, the thermal neutron filter is arranged, and the thermal neutron filtering material is adopted to remove the thermal neutrons in the moderated neutrons, so that the cooling problem after activation can be relatively simple, and the requirement on cooling is reduced. Further, on the premise of the maximum passing rate, besides gold, if gamma rays contributed by other elements are strong, the system is blocked, and gold is difficult to analyze.
(2)198Generation of Au into beta-Decay to form198Hg, test1198The intensity of gamma rays emitted by the decay of Au is used for obtaining the gold grade of the gold ore to be detected
According to the embodiment of the invention, when the activated gold ore sample to be detected is detected, the detection can be carried out under the condition that the reference material exists, and particularly, the reference material can be processed together with the gold ore sample to be detected, so that the system error can be further reduced.
According to the embodiment of the invention, a high-purity germanium spectrometer can be used for testing198The intensity of gamma rays emitted by Hg, specifically, the irradiated gold ore sample to be measured is transmitted to a high-purity germanium detector for measurement, and high-purity germanium crystals are used for collection198Gamma photons emitted by Au, an energy spectrometer converts signals measured by a high-purity germanium detector into an energy spectrum, and gold content information is obtained after computer analysis. Wherein, when the high-purity germanium spectrometer is used for measurement, the spectrometer system can be obtained simultaneouslyFrom the slow-onset gamma ray spectra produced by gold elements, reference plate elements and other elements, we require a characteristic gamma ray of gold of 411 keV. Taking the Br reference material as an example, the characteristic gamma ray of interest is 777keV, and the mass fraction of gold in the sample can be calculated using the following formula.
Wherein:
n is a Br characteristic gamma 777keV net count detected by the detector;
N0is a reference material81The number of Br atoms;
sigma is81A Br neutron capture reaction cross section;
lambda is an activating nucleus82A Br decay constant;
tirris the irradiation duration;
tcoolthe time interval between the end of irradiation and the start of measurement;
tmto measure the duration;
εp-sefficiency of peak source detection for a 777keV gamma ray pair;
εbis composed of82Br produced a branching ratio of 777keV gamma rays.
Wherein:
n' is Au characteristic gamma 411keV net count detected by the detector;
N′0is in a sample197The number of Au atoms;
σ' is97Au neutron capture reaction cross section;
lambda' is an activating nucleus198The Au decay constant;
ε′p-speak source detection efficiency for a detector pair 411keV gamma rays;
ε′bis composed of198Au produces a branching ratio of 411keV gamma rays.
Wherein:
MAu＝197relative atomic mass of Au;
NAavogalois constant;
mass m is gold ore sample;
grade-gold mass ratio in the sample.
When the reference material includes a plurality of materials, the neutron dose rate can be obtained
And further calculating to obtain the mass ratio of gold in the gold ore sample to be detected.
Based on the same inventive concept, in yet another aspect of the present invention, a system for analyzing grade of gold ore is provided. According to an embodiment of the invention, the system comprises:
an activation system 100 and a high purity germanium spectrometer 200. Wherein, the activation system 100 comprises an electron accelerator 110, an electron conversion target 120, a neutron conversion body 130, an irradiation cavity 140, a neutron moderating body 150, the electron accelerator 110 is adapted to provide accelerated electrons 111 and bombard the electron conversion target 120 with the accelerated electrons 111; the neutron conversion body 130 defines a conversion cavity within which the electron conversion target 120 is disposed and adapted to generate X-rays 121 under bombardment by accelerated electrons, the neutron conversion body 130 adapted to convert the X-rays 121 into neutrons 131; the irradiation cavity 140 is arranged at one side of the neutron conversion body 130 and is of a sealable structure, the neutron moderating body 150 is arranged along the circumferential direction of the irradiation cavity 140, and the neutron moderating body 150 is suitable for realizing the feeding of the gold ore sample A to be detectedDischarging the irradiation cavity 140 and moderating the neutrons 131, wherein the irradiation cavity 140 is suitable for accommodating the gold ore sample A to be detected and activating the gold ore sample A to be detected by using the moderated neutrons so as to enable the gold ore sample A to be detected to be in197Conversion of Au to198Au; the high-purity germanium spectrometer 200 comprises a germanium detector 210, an energy spectrometer 220, a refrigerating device 230 and a computer 240, wherein the germanium detector 210 is suitable for collecting (delayed) gamma rays 250 emitted by a gold ore sample a to be detected, the energy spectrometer 220 is suitable for converting gamma ray signals detected by the germanium detector 210 into an energy spectrum, the computer 240 is suitable for analyzing the energy spectrum to obtain the content of gold in the gold ore sample a to be detected, and the refrigerating device 230 is suitable for providing a low-temperature environment for germanium crystals in the germanium detector 210.
The system for analyzing the grade of the gold ore in the embodiment of the invention at least has the following beneficial effects: a. the electron accelerator is utilized to prepare the photon source, the electron accelerator has good stability, the flow intensity can also reach a large value, a strong neutron beam can be provided, the size of the electron accelerator is small, the electron accelerator is suitable for industrial production, and compared with an isotope source, a neutron generator, a reactor, a spallation source and the like used in the existing laboratory, the neutron source is more practical and reliable, the neutron yield is high, the occupied area is small, the electron accelerator can be used for industrial field application, and accurate and efficient analysis of gold ore grade is realized. b. When the neutrons are adopted to activate the gold ore to be tested, the neutrons need a slower speed to effectively react with the gold, if the neutrons have a faster speed, the reaction capability with the gold is poorer, the reaction efficiency is low, and the test sensitivity is poorer. c. The gold ore to be tested is activated in an activation system in advance, and then the activated gold ore to be tested is tested by adopting a high-purity germanium spectrometer because197The half-life of the prompt gamma emitted after the Au captures the neutron is extremely short, so that the sample can be transferred in the process197Transient gamma emitted by Au activation is completely eliminated, so that the interference of the transient gamma to the slow-emitting gamma with a longer half-life period is avoided, and the accuracy and the reliability of the test structure are ensured. d. By usingWhen the system is used for analyzing the grade of gold ore, the system is characterized in that198The long half-life of Au (2.6 days) is limited relative to photon activation methods197The half-life of Au homogeneous and heterogeneous energy state is shorter (7s) so that higher analysis precision cannot be obtained, and the slow-release gamma can be used as197The marker of the existence of Au can be accumulated and counted under a long time scale (minutes, hours and days) according to actual requirements, so that better measurement statistics can be obtained, and the measurement precision can be ensured. e. The system also has the advantages of simple structure, high measurement precision and easy realization of industrial production.
According to an embodiment of the present invention, the activation system 100 may further include a thermal neutron filter 160, the thermal neutron filter 160 is disposed on an inner surface of the irradiation cavity 140, and may specifically be designed in a layered structure, and by disposing the thermal neutron filter, thermal neutrons in the moderated neutrons may be removed in advance, and the obtained moderated neutrons may be used to irradiate the gold ore to be detected, so that not only may the gamma counting rate of other elements in the ore be reduced, and the signal-to-noise ratio when analyzing gold be improved, but also the cooling problem after activation may be relatively simple, and the requirement for cooling may be reduced. The thermal neutron filter 160 may be made of metal gadolinium and/or metal cadmium, such as a metal gadolinium sheet and/or a metal cadmium sheet, and the thickness of the layered thermal neutron filter may be 0.8-1.2 mm, and preferably may be not less than 1 mm. In this case, the signal of the species that produce interfering radioactivity due to thermal neutron absorption is reduced by more than 2 orders of magnitude (simulation calculation: 147 times), while the signal of gold element is reduced by only 60% (simulation result: 38.6%), and the cost ratio is thus improved by nearly 2 orders of magnitude (simulation calculation: 56 times). In practice, this cost ratio improves even more when the thickness of the cadmium sheet is changed to be thicker, or a gadolinium sheet with better thermal neutron absorption (0.8 mm thickness reduces the signal of interfering radioactive species by more than 2 orders of magnitude).
According to an embodiment of the present invention, the activation system 100 may further comprise a reference material 170, the reference material 170 is adapted to move together with the gold ore sample to be tested, i.e. to be fed into/out of the irradiation chamber together with the whole process of activation and detection of the gold ore to be tested, the inventors found that, when the detection is performed, the stability of the accelerator, the size and the kind of material of the sample to be tested, etc. all affect the neutron field in the irradiation chamber, so that the neutron field in the irradiation chamber is affected, thereby the detection is performed197The analytical sensitivity of Au also changed, and thus the analysis was carried out198In order to solve the problem that the content of the gold element is analyzed by the Au gamma ray, errors can occur, one or more reference materials can be placed in the irradiation cavity to detect the inconsistency of the neutron irradiation field, and systematic errors are eliminated, wherein the reference materials enter, irradiate and leave the irradiation cavity along with the gold ore sample to be detected, namely, the irradiation time of the reference materials and the irradiation time of the sample are completely the same. Further, in order to better eliminate the systematic error caused by the above interference factors, when selecting the reference material, it is preferable that the half-life period and the half-life period of the generated radionuclide when the element in the reference material is irradiated by the neutron198The half-life of Au cannot be greatly different, and the energy of the generated gamma rays cannot be greatly different, so that the material of the reference material can be preferably selected from at least one of Eu, In, Mn, Ir, Re, W, La, Sb, Dy, As, Ga, Yb and Br, and the reference material is selected to be more favorable for reducing system errors. Furthermore, one or more reference materials and/or one or more reference materials made of one or more materials can be arranged in the circumferential direction of the gold ore to be detected, so that systematic errors can be eliminated; more preferably, In order to better monitor the irradiation condition of the gold ore sample to be measured, multiple and multiple reference materials may be used, so that the reference materials are disposed In multiple directions of the gold ore sample to be measured, for example, Eu, In, etc. may be placed at the upper, lower, left, right, etc. positions of the sample to be irradiated. It should be noted that the existence form of the reference material is not particularly limited, and those skilled in the art can select the reference material according to actual needs, for example, the reference material may be a sheet or a ringShape, etc.
According to the embodiment of the invention, the errors can be further eliminated by combining the arrangement of the cooling and thermal neutron filters and the reference sheet at the same time, and the accuracy and the reliability of the test result are provided. More preferably, the neutron moderating body may be arranged in the circumferential direction of the irradiation chamber, the circumferential direction of the neutron conversion body, and the circumferential direction of the electron accelerator, whereby the moderating effect on neutrons can be further ensured. According to a specific example of the present invention, the gold ore sample a to be measured may be transported to the irradiation chamber by using the conveyor 300 and then transported to the high purity germania spectrometer 200, specifically, the gold ore sample a to be measured may be introduced into the irradiation chamber while the movable neutron moderating body 151 is in an open state, then the movable neutron moderating body 151 is closed again, so that a closed neutron field appears in the irradiation chamber, and when the irradiation time is completed, the movable neutron moderating body 152 is opened and the gold ore sample a to be measured is removed.
According to an embodiment of the invention, the neutron moderator material may be a hydrogen containing material. The inventor finds that hydrogen is a good neutron moderating material, the mass of the hydrogen is almost the same as that of neutrons, and when neutrons collide with protons, the energy of the neutrons is more easily consumed to be moderated, so that a remarkable neutron moderating effect is achieved. It is understood that the kind of the hydrogen-containing material in the present invention is not particularly limited, and those skilled in the art can flexibly select the material according to the actual needs, for example, a material with a high hydrogen content may be preferred as the neutron moderating body, such as water, polyethylene, polypropylene, or paraffin, so as to achieve a better moderating effect.
According to an embodiment of the present invention, the specific arrangement of the neutron converter is not particularly limited, and may be selected by a person skilled in the art according to actual needs, for example, the neutron converter may define a conversion cavity, and the conversion cavity may be filled with a neutron conversion material (such as water or beryllium), so that the electron conversion target is located in the neutron conversion material. For another example, when heavy water is selected as the neutron conversion material, the neutron conversion material can be packaged by an aluminum can, so that the heavy water in the aluminum can generates neutrons, wherein the aluminum can is almost transparent to the neutrons; when beryllium is selected as the neutron conversion material, beryllium packaging can be directly adopted, even if the neutron moderating body is of an integrated structure.
The system for analyzing grade of gold ore and the method for analyzing grade of gold ore according to the above embodiments of the present invention are proposed based on the same inventive concept, and the method for analyzing grade of gold ore according to the above embodiments of the present invention may be implemented. In addition, it should be noted that the features and effects described for the method for analyzing grade of gold ore are also applicable to the system for analyzing grade of gold ore, and are not described in detail herein.
In summary, the method and system for analyzing gold ore grade according to the above embodiments of the present invention may have the following beneficial effects:
1. the electron accelerator has very good stability, the flow intensity can also reach very big, can provide very strong neutron beam, and the size of electron accelerator is very little, be suitable for industrial production and use, compare with isotope source, neutron generator, reactor, spallation source etc. that current laboratory used, not only more practical, reliable, and neutron yield is high, area is little, can be used for the use of industrial field, realize accurate, the high-efficient analysis of gold ore grade.
2. The neutron can be moderated, the reaction efficiency of the neutron and gold is improved, and the test sensitivity and the accuracy and reliability of a test result are improved.
3. Can use the delayed gamma as197The gold content is analyzed by analyzing the quantity of the markers for the existence of Au, so as to realize the analysis of the grade of the gold ore, wherein, before the strength of the slow-emitting gamma ray is tested, the markers can be used in the sample transfer process197Transient gamma emitted by Au activation is completely eliminated, so that the interference of the transient gamma to the slow-emitting gamma with a longer half-life period is avoided, and the accuracy and the reliability of the test structure are ensured.
4. Based on the high cost ratio analysis of the optical neutron resonance activation, a thermal neutron filter can be arranged around the gold ore sample to filter out thermal neutrons, so that the counting rate of gamma rays generated by other elements is inhibited, and meanwhile, 4.9eV resonance neutrons of gold are retained, so that the counting rate of gamma rays generated by gold elements is not obviously influenced, and the cost ratio (2 quantum levels or higher) is obviously improved. In addition, as the radioactive signals of the interference elements are not manufactured any more, the effective counting rate of the signals is greatly improved on the premise of limited system throughput rate, and the analysis speed is accelerated; furthermore, the total radioactivity level during the sample measurement is thus reduced, which is important for online use. Furthermore, the interference of other elements can be further reduced by cooling.
5. The method has no systematic deviation and high accuracy, can be provided with a reference sheet, places the reference sheet and the gold ore sample in the same neutron field, irradiates the reference sheet and the gold ore sample simultaneously, measures gamma rays generated by the reference sheet and the gold ore sample, analyzes the content of gold elements by using a relative method, eliminates systematic errors caused by instability of an accelerator system and a detector system, and ensures the accuracy of system measurement.
6. More measurement counts and high measurement precision, and under the premise that the passing rate of a detection system is limited, a plurality of counts cannot be accumulated in a short time, so that good statistics is obtained. In the present invention, delayed gamma was used as a marker for the presence or absence of 197Au, i.e., measurement198The radioactivity of Au, which has a long half-life (2.6 days), is limited relative to photon activation methods197The method has the advantages that the half-life of Au in the homogeneous and heterogeneous energy state is short (7s), so that higher analysis accuracy cannot be obtained, the counting can be accumulated under a long time scale (minutes, hours and days) according to actual requirements, better measurement statistics can be obtained, and the measurement accuracy can be guaranteed.
7. Simple, high measurement precision and easy realization of industrial production.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (10)
1. A method of analyzing the grade of a gold ore, comprising:
(1) activating the gold ore to be tested by using neutrons so as to ensure that the neutrons in the gold ore to be tested197Activation of Au to198Au；
(2)198Generation of Au into beta-Decay to form198Hg, test198The intensity of gamma rays emitted by Au decay so as to obtain the gold grade of the gold ore to be detected.
2. The method of analyzing gold ore grade according to claim 1, wherein step (1) comprises:
(1-1) generating accelerated electrons using an electron accelerator;
(1-2) bombarding an electron conversion target with the accelerated electrons to obtain X rays;
(1-3) converting the X-ray into a neutron using a neutron converter;
(1-4) converting the neutrons into moderated neutrons using a neutron moderating body;
and (1-5) irradiating the gold ore to be detected with the moderated neutrons to perform the activation.
3. The method of analyzing gold ore grade according to claim 2, wherein in step (1-1), the accelerated electron energy is not higher than 10 MeV;
optionally, step (1-5) further comprises: removing thermal neutrons in the moderated neutrons, and irradiating the gold ore to be detected by using the obtained moderated neutrons;
optionally, step (1-5) satisfies at least one of the following three conditions: (i) the irradiation time is not less than 1 s; (ii) cooling the activated gold ore to be detected; (iii) and removing thermal neutrons in the moderating neutrons by utilizing metal gadolinium and/or metal cadmium.
4. A method of analysing gold ore grade according to any of claims 1 to 3, wherein the activation In step (1) and the testing In step (2) are carried out In the presence of a reference material of a material selected from at least one of Eu, In, Mn, Ir, Re, W, La, Sb, Dy, As, Ga, Yb and Br,
optionally, one or more reference materials and/or one or more reference sheets made of materials are arranged on the circumferential direction of the gold ore to be detected.
5. The method of analyzing gold ore grade of claim 4, wherein the testing is by high purity germanium spectrometer198The intensity of gamma rays emitted by the decay of Au, and the mass ratio of the gold to be detected is
Wherein M isAuIs composed of197Relative atomic mass of Au;
N′0in the gold ore sample to be tested197The number of Au atoms;
NAis an Avogastron constant;
m is the quality of the gold ore sample to be detected;
and Grade is the mass ratio of gold in the gold ore sample to be detected.
6. The method of analyzing gold ore grade of claim 5, wherein the gold ore sample to be tested is gold ore sample197N 'of Au atom number'0The formula is as follows:
wherein the content of the first and second substances,
n' is Au characteristic gamma 411keV net count detected by a germanium detector in a high-purity germanium spectrometer;
σ' is197Au neutron capture reaction cross section;
lambda' is an activating nucleus198The Au decay constant;
ε′p-sthe detection efficiency of the germanium detector in the high-purity germanium spectrometer on the peak source of the 411keV gamma ray is obtained;
ε′bis composed of198Au produces a branch ratio of 411keV gamma rays;
n is a characteristic gamma net count generated after nuclide of a reference material detected by a germanium detector in a high-purity germanium spectrometer is activated;
N0is the atomic number of the species of the reference material;
sigma is a nuclide neutron capture reaction section of a reference material;
λ is the decay constant of the reference material after nuclide activation;
tirris the irradiation duration;
tcoolthe time interval between the end of irradiation and the start of measurement;
tnmeasuring time length for a high-purity germanium spectrometer;
εp-sthe peak source detection efficiency of characteristic gamma rays generated after a germanium detector in a high-purity germanium spectrometer activates nuclides of a reference material is obtained;
εbis the branch ratio of the gamma rays generated after the nuclide activation of the reference material.
7. A system for analyzing the grade of a gold ore, comprising:
the activation system comprises an electron accelerator, an electron conversion target, a neutron conversion body, an irradiation cavity and a neutron moderating body, wherein the electron accelerator is suitable for providing accelerated electrons and bombarding the electron conversion target by the accelerated electrons; the neutron conversion body defines a conversion cavity, the electron conversion target is arranged in the neutron conversion cavity and is suitable for generating X rays under the bombardment of the accelerated electrons, and the neutron conversion body is suitable for converting the X rays into neutrons; shine the chamber and establish one side of neutron conversion body and for enclosed construction, neutron moderation body is followed the circumference in irradiation chamber is arranged, neutron moderation body is suitable for realizing the gold ore sample business turn over that awaits measuring shine the chamber with right the neutron moderation, it is suitable for holding to shine the chamber the gold ore sample that awaits measuring and utilize moderation neutron right the gold ore sample that awaits measuring activates, makes in the gold ore sample that awaits measuring197Conversion of Au to198Au；
The high-purity germanium spectrometer comprises a germanium detector, an energy spectrometer, a refrigerating device and a computer, wherein the germanium detector is suitable for collecting gamma rays emitted by the gold ore sample to be detected, the energy spectrometer is suitable for converting gamma ray signals detected by the germanium detector into an energy spectrum, the computer is suitable for analyzing the energy spectrum to obtain the content of gold in the gold ore sample to be detected, and the refrigerating device is suitable for providing a low-temperature environment for germanium crystals in the germanium detector.
8. The system of claim 7, wherein the activation system further comprises a thermal neutron filter disposed on an interior surface of the irradiation chamber;
optionally, the material of the thermal neutron filter is metal gadolinium and/or metal cadmium;
optionally, the neutron filter has a thickness of no less than 1 mm;
optionally, the activation system further comprises a reference material adapted for co-movement with the gold ore sample to be tested;
optionally, the reference material is arranged in one or more directions of the gold ore sample to be detected;
optionally, the material of the reference sheet is selected from at least one of Eu, In, Mn, Ir, Re, W, La, Sb, Dy, As, Ga, Yb and Br.
9. The system of claim 7 or 8, wherein the conversion cavity is filled with a neutron conversion material, the electron conversion target being located in the neutron conversion material;
optionally, the neutron moderator material is a hydrogen containing material.
10. A system according to claim 7 or 8, for carrying out the method of analysing gold ore grade according to any one of claims 1 to 6.
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