A method and device for measuring magnetic anomaly in iron ore

Abstract

The invention discloses a method and equipment for measuring iron ore magnetic anomaly. The method comprises: selecting a potential iron ore magnetic anomaly area in a volcanic rock area or a surrounding rock Q value greater than 1 and an iron ore Q value less than 1; establishing an abnormal daily variation station and a background daily variation station inside and outside the potential iron ore magnetic anomaly area, respectively, measuring and recording first magnetic daily variation data of the abnormal daily variation station and second magnetic daily variation data of the background daily variation station, and simultaneously calculating the noise probability contained in the first magnetic daily variation data and the second magnetic daily variation data; selecting a magnetic field continuous variation period in which the noise probability is lower than a preset threshold, extracting the starting point and the end point of the magnetic field continuous variation period, and calculating the magnetic anomaly intensity variation, the normalized magnetic anomaly intensity variation F value, and the Q value of the magnetic anomaly source; and when the normalized magnetic anomaly intensity variation F value is greater than 0.5 and the Q value of the magnetic anomaly source in the potential iron ore magnetic anomaly area is less than 1, judging that the potential iron ore magnetic anomaly is caused by magnetite.

Description

Technical Field

[0001] The present invention belongs to the field of magnetic prospecting, and in particular relates to a method and device for measuring magnetic anomalies in iron ore. Background Art

[0002] Most iron ores in my country are highly magnetic, and iron ore bodies generally produce strong magnetic anomalies. Magnetic methods have played a significant role in iron ore prospecting, exploration, and research. Nearly 90% of magnetite discoveries are based on magnetic anomalies. Currently, aeromagnetic surveys alone have revealed over 90,000 magnetic anomalies, but only a little over 10,000 have been verified, representing only about 15% of the discovered anomalies. While many iron ore bodies exhibit magnetic anomalies, they are not necessarily the cause. Surface mineral deposits have largely been discovered, and prospecting efforts need to advance into hidden areas, even at depth. However, currently, apart from drilling, there is no direct method to determine whether a magnetic anomaly has the potential to reveal iron ore.

[0003] Currently, magnetic exploration is a commonly used method for studying the geological properties of magnetic bodies based on the physical properties of rocks and ores and the characteristics of magnetic anomalies. It can be used to delineate metamorphic rocks, volcanic rocks, intrusive rocks, altered rocks, faults, volcanic structures, magnetite, and magnetite-bearing polymetallic ores. This work is primarily based on the characteristics of magnetic anomalies, their geological environment and mineralization conditions, information on discovered strata, rocks, ore bodies, and magnetic characteristics, combined with other geophysical and geochemical anomalies. This research method is entirely a logical reasoning from the known to the unknown, with a large amount of uncertainty and potential discrepancies with the actual situation. The correctness of the inferred results can currently only be verified through drilling. However, drilling is very expensive, making it difficult to invest a large amount of drilling work to determine whether magnetic anomalies have the potential to explore iron ore.

[0004] In view of this, overcoming the cost and technical defects of the above-mentioned prior art is an urgent problem to be solved in this technical field. Summary of the Invention

[0005] In response to the above-mentioned defects or improvement needs of the prior art, the present invention provides a method and equipment for measuring magnetic anomalies in iron ore, the purpose of which is to quickly determine whether the potential magnetic anomaly in iron ore is caused by an iron ore body, thereby solving the technical problem that can only be measured by actual drilling survey.

[0006] To achieve the above object, according to one aspect of the present invention, a method for measuring magnetic anomaly in iron ore is provided, the method comprising:

[0007] Select potential iron ore magnetic anomaly areas in volcanic rock areas or ore clusters where the Q value of surrounding rocks is greater than 1 and the Q value of iron ore is less than 1;

[0008] Establishing an abnormal daily variation station and a background daily variation station within and outside the potential iron ore magnetic anomaly area, respectively, measuring and recording first daily magnetic variation data of the abnormal daily variation station and second daily magnetic variation data of the background daily variation station, and calculating the noise probability contained in the first daily magnetic variation data and the second daily magnetic variation data;

[0009] Selecting a period of continuous magnetic field change during which the noise probability is lower than a preset threshold, extracting the starting point and end point of the period of continuous magnetic field change, and calculating the magnetic anomaly intensity change ΔA, the normalized magnetic anomaly intensity change F value, and the Q value of the magnetic anomaly source;

[0010] When the normalized magnetic anomaly intensity change F value is greater than 0.5 and the Q value of the magnetic anomaly source in the potential iron ore magnetic anomaly zone is less than 1, it is determined that the potential iron ore magnetic anomaly is caused by magnetite.

[0011] As a further improvement and supplement to the above solution, the present invention also includes the following additional technical features.

[0012] Preferably, the abnormal daily variation station is located in the area from the maximum to the maximum / 2 or from the minimum to the minimum / 2 of the potential iron ore magnetic anomaly, and the distance between the background daily variation station and the potential iron ore magnetic anomaly is less than or equal to 30 km.

[0013] Preferably, the method for calculating the noise probability contained in the first diurnal magnetic variation data and the second diurnal magnetic variation data includes:

[0014] Noise probability P(P t ∈Pz t 、Py t ),and:

[0015] in,

[0016] Where: D t It is the distance from the magnetic field data at a certain time t of the background daily variation station or the abnormal daily variation station to the straight line containing the magnetic field data at time t-1 and time t+1. H is the geomagnetic field T or one of the three magnetic components N, E, and V of the geomagnetic field.

[0017] Preferably, the method of selecting the magnetic field continuous change period in which the noise probability is lower than a preset threshold comprises:

[0018] The period of continuous magnetic field change is when the first magnetic daily variation data of the abnormal daily variation station and the second magnetic daily variation data of the background daily variation station increase or decrease synchronously, and the noise probability is less than 5%.

[0019] Preferably, the method for extracting the starting point and the end point during the continuous change of the magnetic field includes:

[0020] During the period of continuous change of the magnetic field, the static magnetic day lasts for more than 2 hours and the daily change of the magnetic field at the background daily change station is greater than 30nT, and the daily change of the magnetic field on magnetic storms or strong magnetic disturbance days is greater than 50nT.

[0021] Preferably, the method of calculating the magnetic anomaly intensity variation ΔA based on the first and second daily magnetic variation data with the starting and ending points respectively determined by recording comprises:

[0022] ΔA=ΔT t2 -ΔT t1

[0023] Where ΔT ti =Ty ti -Tz ti ,i∈(1,2)

[0024] Where: ΔT t1 Indicates the magnetic anomaly value at the starting point, ΔT t2 Indicates the magnetic anomaly value at the end point, Ty t2 Indicates the end point magnetic field value of the abnormal daily variation station; Ty t1 Indicates the starting point magnetic field value of the abnormal daily variation station; Tz t2 Indicates the end point magnetic field value of the background daily variation station; Tz t1 Indicates the starting point magnetic field value of the background daily variation station.

[0025] Preferably, the method of extracting the starting point and the end point of the continuous change of the magnetic field and calculating the change in magnetic anomaly intensity ΔA further includes:

[0026] ΔA=(Mi t2 -Mi t1 )×S;

[0027] in:

[0028] Among them, Mi t is the induced magnetization intensity at time t, S is the spatial information, is the unit vector of the magnetic moment at the magnetic dipole Q point, is the unit vector of the Earth's magnetic field, is the unit vector of the distance from the magnetic dipole Q point to the abnormal daily variation station or the background daily variation station, r is the distance from the magnetic dipole Q point to the abnormal daily variation station or the background daily variation station, v is the volume of the magnetic anomaly source, and μ0 is the vacuum magnetic permeability.

[0029] Preferably, the method of calculating the normalized magnetic anomaly intensity change F value based on the first and second daily magnetic variation data with the starting and ending points determined respectively includes:

[0030]

[0031] When Mi << Mr, Ft ≈ 0;

[0032] When Mi >> Mr,

[0033] If Mi ≈ Mr, then

[0034] where κ is the magnetic susceptibility, μ0 is the magnetic permeability of vacuum, and Mr is the remanent magnetization.

[0035] Preferably, the method for calculating the Q value of the magnetic anomaly source by using the first magnetic diurnal variation data and the second magnetic diurnal variation data that respectively determine the starting point and the ending point according to the records includes:

[0036]

[0037] According to another aspect of the present invention, there is provided a device for determining ore-induced magnetic anomalies of iron ore, characterized in that the device includes:

[0038] One or more processors;

[0039] A storage device for storing one or more programs, which when executed by the one or more processors, cause the one or more processors to implement the method for determining ore-induced magnetic anomalies of iron ore as described in the first aspect.

[0040] Generally speaking, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:

[0041] The method for determining ore-induced magnetic anomalies of iron ore provided by the present invention can quickly determine whether the potential ore-induced magnetic anomalies in areas where the Q value of the surrounding rock is greater than 1 and the Q value of the iron ore is less than 1 are caused by iron ore bodies, greatly reducing the prospecting risk, reducing the investment cost, so as to improve the current iron ore exploration efficiency, and having great potential economic value. Brief Description of the Drawings

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments of the present invention. Obviously, the following described drawings are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings without creative efforts.

[0043] Figure 1 It is a schematic flow chart of a method for determining ore-induced magnetic anomalies of iron ore provided in Embodiment 1;

[0044] Figure 2 It is a plan view of aeromagnetic ΔT isolines and a distribution map of potential ore-induced magnetic anomalies of iron ore and diurnal variation stations provided in Embodiment 1;

[0045] Figure 3 is the consistency test result of the magnetometer in the first embodiment;

[0046] Figure 4 This is the test result of the example background daily change station in the first embodiment of this invention;

[0047] Figure 5 This is the time-magnetic field diagram of the Mengbaizhuang abnormal daily variation station and the background daily variation station in the first embodiment;

[0048] Figure 6 This is the time-magnetic field diagram of the Wangwangzhuang abnormal daily variation station and the background daily variation station in the first embodiment;

[0049] Figure 7 This is the time-magnetic field diagram of the Beijinzhao abnormal daily variation station and the background daily variation station in the first embodiment;

[0050] Figure 8 This is the time-magnetic field diagram of the Houzhuang abnormal daily variation station and the background daily variation station in the first embodiment;

[0051] Figure 9 This is a schematic diagram of an apparatus for measuring magnetic anomalies in iron ore provided in the second embodiment. DETAILED DESCRIPTION

[0052] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0053] Example 1

[0054] This embodiment provides a method for measuring magnetic anomaly in iron ore, the method comprising: Figure 1 Steps shown:

[0055] S101: Select potential iron ore magnetic anomaly areas in volcanic rock areas or ore clusters where the Q value of the surrounding rock is greater than 1 and the Q value of the iron ore is less than 1.

[0056] The Q value in volcanic rock areas is generally greater than 1. The relationship between the Q value of the surrounding rock of the iron ore body and the Q value of the iron ore is basically consistent within the same ore cluster, but varies from one ore cluster to another. In some ore clusters, the Q value of the surrounding rock is greater than the Q value of the iron ore, while in others, the Q value of the surrounding rock is less than the Q value of the iron ore. Therefore, in volcanic rock areas or ore clusters where the Q value of the surrounding rock is greater than 1 and the Q value of the iron ore is less than 1, the F value (which theoretically has a similar variation pattern to the Q value) and the Q value can be used to determine whether the potential iron ore-induced magnetic anomaly is caused by iron ore, that is, magnetite.

[0057] S102: Establish an abnormal daily variation station and a background daily variation station in and outside the potential iron ore magnetic anomaly area, measure and record the first magnetic daily variation data of the abnormal daily variation station and the second magnetic daily variation data of the background daily variation station, and calculate the noise probability contained in the first magnetic daily variation data and the second magnetic daily variation data.

[0058] The potential iron ore magnetic anomaly is located in the iron ore mineralization zone, which has the geological, structural and other factors required for the formation of iron ore, and there is iron ore production nearby. The magnetic anomaly intensity and gradient are relatively large.

[0059] like Figure 2 As shown, the locations of potential iron ore magnetic anomalies, as well as pre-selected anomaly and background daily variation stations, are marked on the aeromagnetic map. Field surveys are conducted to determine the locations of anomaly and background daily variation stations. Anomaly and background daily variation stations should be located within the area between the maximum and maximum / 2 or minimum and minimum / 2 of the potential iron ore magnetic anomaly, with minimal surface human interference and relatively open terrain (no pits). Background daily variation stations should be less than 30 km from the potential iron ore magnetic anomaly, with a calm magnetic field, a small gradient (magnetic field gradient <1nT / 2m), minimal human interference (more than 15m from buildings, and away from transportation lines, power lines, etc.), and flat and open terrain.

[0060] This embodiment uses two GSM-19 magnetometers and two GSM-19T magnetometers. The GSM-19 magnetometer has a sensitivity of 0.015nT, a resolution of 0.01nT, and an absolute accuracy of ±0.1nT; the GSM-19 magnetometer has a sensitivity of 0.05nT, a resolution of 0.01nT, and an absolute accuracy of ±0.2nT. They are all magnetometers that can continuously measure and automatically save data. Figure 3 As shown, the magnetometers and other equipment used are tested to ensure that they are in the correct state, and different equipment should ensure that the measurement data is synchronized. The adoption rate of magnetic field measurement in this embodiment is 1 / 2 minutes. Figure 2 and Figure 4 As shown in the figure, a field investigation was conducted on the pre-selected abnormal daily variation stations and background daily variation stations, and the locations of the abnormal daily variation stations and background daily variation stations were finally determined.

[0061] When measuring and recording the magnetic field data at different times of the diurnal variation station, the measurement time is selected from 09:00 to 17:00; the recorded data includes: measurement point coordinates, time, and magnetic field value. At the same time, after measuring and recording the magnetic field data at different times of the diurnal variation station, the probability P of noise in the magnetic diurnal variation data at each moment can be obtained through data processing. t .

[0062] In the first embodiment, a method for estimating the probability P of noise contained in measurement data is proposed.

[0063] Noise probability P(P t ∈Pz t 、Py t ),and:

[0064] in,

[0065] D t It is the distance from the magnetic field data at a certain time t of the background daily variation station or the abnormal daily variation station to the straight line containing the magnetic field data at time t-1 and time t+1. H is the geomagnetic field T or one of the three magnetic components N, E, and V of the geomagnetic field.

[0066] If P t ≈0, indicating that there is basically no noise in the measurement data at time t; P t The larger it is, the greater the probability that the measured data at time t contains noise.

[0067] The method for selecting the magnetic field continuous change period in which the noise probability is lower than a preset threshold comprises:

[0068] The period of continuous magnetic field change is when the first magnetic daily variation data of the abnormal daily variation station and the second magnetic daily variation data of the background daily variation station increase or decrease synchronously, and the noise probability is less than 5%.

[0069] S103: Selecting a period of continuous magnetic field change in which the noise probability is lower than a preset threshold, extracting the starting point and end point of the period of continuous magnetic field change, and calculating the magnetic anomaly intensity change ΔA, the normalized magnetic anomaly intensity change F value, and the Q value of the magnetic anomaly source.

[0070] Since the geomagnetic field is not constant but changes with time, the intensity of magnetic anomalies caused by rocks or ores mainly includes two parts, namely the anomaly caused by the residual magnetization intensity Mr and the anomaly caused by the induced magnetization intensity Mi. The former is retained after the rock or ore was magnetized by the geomagnetic field at the time of its formation, and the latter is produced by the rock or ore being magnetized by the current geomagnetic field. Therefore, the intensity of magnetic anomalies caused by rocks or ores will also change with the continuous changes in the geomagnetic field intensity.

[0071] First, anomaly daily variation stations and background daily variation stations were established inside and outside the potential iron ore magnetic anomaly area, and the first magnetic daily variation magnetic field value Ty of the anomaly daily variation station at each time during a period of time was measured. t and the second magnetic field value Tz of the background daily variation station t , calculate the magnetic field difference ΔT at the two diurnal variation measurement stations at the same time t , that is, to obtain the magnetic anomaly intensity value at each moment, the calculation formula is:

[0072] ΔT t =Ty t -Tzt

[0073] Since the geomagnetic field changes very slowly during the solar quiet day, even the magnetic field changes during the magnetic storm are very small compared to the geomagnetic field strength (generally greater than 50000nT), so the change value of the magnetic anomaly intensity in a short period of time is very small and difficult to separate from various noises. t Indicates the first magnetic field value of the abnormal daily variation station, Tz t Indicates the second magnetic field value of the background daily variation station, Ty t2 Indicates the end point magnetic field value of the abnormal daily variation station; Ty t1 Indicates the starting point magnetic field value of the abnormal daily variation station; Tz t2 Indicates the end point magnetic field value of the background daily variation station; Tz t1 The starting magnetic field value of the background daily variation station can be used to obtain the change in magnetic anomaly intensity ΔA. The calculation formula is: ΔA=ΔT t2 -ΔT t1 ;

[0074] Where ΔT ti =Ty ti -Tz ti ,i∈(1,2);

[0075] Where: ΔT t1 Indicates the magnetic anomaly value at the starting point, ΔT t2 Indicates the magnetic anomaly value at the end point, Ty t2 Indicates the end point magnetic field value of the abnormal daily variation station; Ty t1 Indicates the starting point magnetic field value of the abnormal daily variation station; Tz t2 Indicates the end point magnetic field value of the background daily variation station; Tz t1 Indicates the starting point magnetic field value of the background daily variation station.

[0076] The calculated change in magnetic anomaly intensity ΔA is related to the induced magnetization intensity, scale, and shape of the magnetic anomaly source. The specific relationship is:

[0077] The magnetic anomaly expression generated by the underground magnetic dipole Q point at time t at a distance r from the measurement point is:

[0078]

[0079] Assume that the source of magnetic anomaly is uniform magnetization, that is, M Qt Regardless of the position Q, the magnetization intensity at time t is constant at M t , and order

[0080]

[0081] but

[0082] ΔTt =M t ·S

[0083] Therefore, the relationship between the change in magnetic anomaly intensity and the induced magnetization intensity, scale and shape of the magnetic anomaly source is:

[0084] ΔA=M t2 ×SM t1 × S=(Mi t2 -Mi t1 )×S

[0085] Among them, M t is the total magnetization intensity at time t, Mi t is the induced magnetization intensity at time t, is the unit vector of the magnetic moment at the magnetic dipole Q point, is the unit vector of the Earth's magnetic field, is the unit vector of the distance from the magnetic dipole Q point to the abnormal daily variation station or the background daily variation station, r is the distance from the magnetic dipole Q point to the abnormal daily variation station or the background daily variation station, and v is the volume of the magnetic anomaly source.

[0086] The magnetic dipole Q point is a magnetic dipole located at point Q. t is the total magnetization intensity at time t, Mi t is the induced magnetization intensity at time t. The magnetization intensity is a property of the magnetic anomaly source. In the formula, it represents the physical characteristics of the magnetic anomaly source and is the detection target. In this embodiment, the magnetization intensity does not need to be known in detail and is only a transition variable.

[0087] The magnetic field strength at time t is measured by magnetometers installed at the anomalous daily variation station and the background daily variation station. Magnetic field strength requires field measurement and is a numerical measure of magnetic field strength.

[0088] Since the change in magnetic anomaly intensity ΔA is generally very small, if the measurement data of the diurnal variation measurement station contains noise, it is difficult to obtain the true change in magnetic anomaly intensity ΔA.

[0089] A preferred implementation scheme for selecting a time period during which the magnetic field continuously increases or decreases is provided in conjunction with an embodiment of the present invention. Specifically, the method for extracting the starting point and the end point during the period during which the magnetic field continuously changes includes:

[0090] During the period when the magnetic field continues to increase or decrease, the static magnetic day lasts for more than 2 hours and the magnetic daily variation at the background daily variation station is greater than 30nT, and the magnetic daily variation on magnetic storm or strong magnetic disturbance days is greater than 50nT; the probability of noise in the first and second magnetic field values at the starting and end points is less than 5%; the calculated change in magnetic anomaly intensity ΔA is greater than the instrument sensitivity.

[0091] Although the change in magnetic anomaly intensity ΔA can characterize the induced magnetization intensity Mi of the magnetic anomaly source to a certain extent, it also contains spatial information S such as the scale, shape, and measurement position of the magnetic anomaly source, so it cannot be quantitatively evaluated. Therefore, it is necessary to calculate the normalized magnetic anomaly intensity change value F using the change in magnetic anomaly intensity ΔA.

[0092] The methods for calculating the normalized magnetic anomaly intensity change F value include:

[0093]

[0094] The calculated F t is only related to the magnetization intensity of the magnetic anomaly source, and the specific relationship is:

[0095]

[0096] When Mi << Mr, F t ≈0;

[0097] When Mi >> Mr,

[0098] If Mi ≈ Mr, then

[0099] where κ is the magnetic susceptibility, μ0 is the magnetic permeability of vacuum, and Mr is the remanent magnetization.

[0100] For example, when Mi = Mr / 9, Ft ≈ 0.10; when Mi = Mr / 99, Ft ≈ 0.01; when Mi = Mr / 999, Ft ≈ 0.001;...

[0101] For example, when Mi = 9Mr, Ft ≈ 0.90; when Mi = 99Mr, Ft ≈ 0.99; when Mi = 999Mr, Ft ≈ 0.999;...

[0102] The Q value, called the Koenigsberger ratio, is the ratio of the remanent magnetization Mr to the induced magnetization Mi, and it can be used to judge the nature of the magnetic anomaly source. For example, the Q value of magnetite ores in China is generally less than 1, while the Q value of strongly magnetic magmatic rocks is generally greater than 1, and thus it can be used to judge whether the magnetic anomaly is caused by iron ore. Currently, generally, a large number of rock or ore specimens are collected, and Mr and Mi are measured indoors, and then the Q value of the rock or ore is obtained. However, the Q value obtained by this method only has statistical significance and can be used to guide research work, but cannot be directly used for geological and mineral exploration.

[0103] In the first embodiment, the method for calculating the Q value of the magnetic anomaly source by respectively determining the first magnetic diurnal variation data and the second magnetic diurnal variation data at the starting point and the ending point according to the records includes:

[0104] From the definition of the Q value:

[0105]

[0106] Mr is the residual magnetization, Mi t is the induced magnetization intensity at time t, and after derivation, we can get:

[0107]

[0108] S104: When the normalized magnetic anomaly intensity change F value is greater than 0.5 and the Q value of the magnetic anomaly source in the potential iron ore magnetic anomaly zone is less than 1, it is determined that the potential iron ore magnetic anomaly is caused by magnetite.

[0109] A large number of studies have shown that my country's magnetite is generally dominated by induced magnetization intensity Mi, and the Q value of magnetite ore is generally between 0.1 and 0.8, and in some cases the Q value is greater than 1.

[0110] In a volcanic rock area or a mineral concentration area where the Q value of the surrounding rock is greater than 1 and the Q value of the iron ore is less than 1, when the normalized magnetic anomaly intensity change F value of the potential iron ore magnetic anomaly area is greater than 0.5 and the Q value of the magnetic anomaly source is less than 1, it is judged that the potential iron ore magnetic anomaly is caused by magnetite.

[0111] like Figure 5 As shown in the figure, the magnetic anomaly caused by the potential iron ore deposit in Mengbaizhuang was discovered by aeromagnetic survey in 1959. The anomaly intensity is as high as 4000nT, with a sharp peak and large gradient, which is the general characteristic of magnetic anomalies caused by magnetite. The buried depth of the magnetic body is 370m by the tangent method and 350m by the different height methods. The magnetic susceptibility of the andesite in the area can reach 20000×4π×10 -5 SI, but it fluctuates unpredictably; the magnetic susceptibility of gabbro is only 2000×4π×10 -5 SI, sandstone, etc. are non-magnetic. In the northeast of the abnormal axis, the Metallurgical Bureau has drilled two holes with a depth of more than 200m. Both holes are pyroxene andesite. The residual magnetization intensity of the core in the hole is 40000×10 -3 A / m, 200000×10 -3 A / m, the Q value of volcanic rocks and basic-ultrabasic rocks is generally > 1. At that time, it was inferred that the anomaly source was andesite, but since no drilling verification was carried out in the anomaly area, people have always been skeptical about whether there is magnetite in the magnetic anomaly source. Figure 2 As shown, an abnormal daily variation station was set up on the east side of the magnetic anomaly maximum. The reason for not setting it at the magnetic anomaly maximum was that the terrain conditions did not meet the requirements. The magnetic anomaly ΔT value at the abnormal daily variation station was 979nT (the difference in magnetic field between the abnormal daily variation station and the background daily variation station). Figure 5As shown, magnetic field values at different times were measured at the anomaly and background daily variation stations in the potential iron ore magnetic anomaly zone of Mengbaizhuang. Calculations show that the probability of noise in the magnetic field values at 12:34:02 for the anomaly and background daily variation stations is 0.01905 and 0.00222, respectively, which can be used as the starting point, t1, of the period of sustained magnetic field variation. The probability of noise in the magnetic field values at 16:14:02 for the background daily variation station is 0.11983 and 0.11317, respectively. The duration of the sustained magnetic field variation is 3 hours and 40 minutes. The magnetic field variation ΔTz at the background daily variation station is 34.48 nT, which is greater than 30 nT, and the change in magnetic anomaly intensity ΔA is 0.25 nT, which is greater than the magnetometer sensitivity. Therefore, 16:14:02 can be used as the end point, t2, of the period of sustained magnetic field variation. Using the magnetic field values at t1 and t2 for the anomaly and background daily variation stations, the F values at both times are calculated to be 0.49, and the Q values are 1.56 and 1.55, respectively. Therefore, the residual magnetization of the anomaly is greater than the induced magnetization, and the possibility that the source of the magnetic anomaly is magnetite is very small.

[0112] like Figure 6 As shown in the figure, the magnetic anomaly caused by the potential iron ore in Wangwangzhuang was discovered by aeromagnetic survey in 1979. The anomaly intensity generally reaches 1500nT at a flight altitude of 45m, and is accompanied by a -500nT anomaly in the north. It has the characteristics of superimposed anomalies, with sharp peaks and large gradients, and has the general characteristics of magnetic anomalies caused by magnetite. The physical property measurement results of the Jinling area are as follows: magnetic susceptibility κ(×4π×10 -5 SI) magnetite 175000 (25000~450000), diorite 500 (0~7000), residual magnetization Mr (×10 -3 A / m) Magnetite 3630 ~ 7300, diorite 0 ~ 2940, diorite Q value is generally > 1, magnetite Q value is generally < 1. At that time, it was inferred that the source of the anomaly was magnetite. Later, drilling discovered a skarn-type iron ore body with a burial depth of about 400m. Figure 2 As shown in the figure, an abnormal daily variation station was set up in the gradient zone west of the magnetic anomaly center. Due to the presence of residential buildings in the area of the magnetic anomaly maximum, an abnormal daily variation station could not be set up there. The magnetic anomaly ΔT value at the abnormal daily variation station is 825nT (the difference in magnetic field between the abnormal daily variation station and the background daily variation station). Figure 6As shown, the magnetic field values of the abnormal daily variation station and the background daily variation station at different times were measured. By calculation, the probabilities of noise existing in the magnetic field values of the abnormal daily variation station and the background daily variation station at 11:58:02 were 0.12126 and 0.30068, respectively, which can be used as the starting point t1 of the continuous change period of the magnetic field; the probabilities of noise existing in the magnetic field values at 16:04:02 were 0.05685 and 0.03300, respectively, and the continuous change time was 4 hours and 6 minutes. The magnetic field change value ΔTz of the background daily variation station was 35.62nT, which was greater than 30nT, and the change in magnetic anomaly intensity ΔA was 0.49nT, which was greater than the sensitivity of the magnetometer. Therefore, 16:04:02 can be used as the end point t2 of the continuous change period of the magnetic field. Using the magnetic field values at the anomaly and background daily variation stations at times t1 and t2, we calculated the F values at these times to be 0.88211 and 0.88218, respectively, and the Q values to be 0.13365 and 0.13356, respectively. Therefore, the residual magnetization of this anomaly is much smaller than the induced magnetization, suggesting a high likelihood that the source of the magnetic anomaly is magnetite, consistent with the exploration results.

[0113] like Figure 7 As shown in the figure, the magnetic anomaly caused by the potential iron ore in Beijinzhao was discovered by aeromagnetic survey in 1979. The intensity of the anomaly is about 2000nT at an altitude of 45m. It has the characteristics of superimposed anomalies, sharp peaks, and large gradients, which are the general characteristics of magnetic anomalies caused by magnetite. The physical property measurement results of Jinling area are as follows: magnetic susceptibility κ(×4π×10 -5 SI) magnetite 175000 (25000~450000), diorite 500 (0~7000), residual magnetization Mr (×10 -3 A / m) magnetite 3630 ~ 7300, diorite 0 ~ 2940, diorite Q value is generally > 1, magnetite Q value is generally < 1. At that time, it was inferred that the source of the anomaly was magnetite. Later, drilling discovered a skarn-type iron ore body with a burial depth of about 100m. Figure 2 As shown in the figure, an abnormal daily variation station was set up in the southwest of the magnetic anomaly center. However, due to the presence of residential buildings in the area of the magnetic anomaly maximum, an abnormal daily variation station could not be set up there. The magnetic anomaly ΔT value at the abnormal daily variation station is 483nT. Figure 7As shown, the magnetic field values of the abnormal daily variation station and the background daily variation station at different times were measured. By calculation, the probabilities of noise existing in the magnetic field values of the abnormal daily variation station and the background daily variation station at 11:52:02 were 0.08970 and 0.12016, respectively, which can be used as the starting point t1 of the continuous change period of the magnetic field; the probabilities of noise existing in the magnetic field values at 16:16:02 were 0.14021 and 0.69757, respectively, and the continuous change time was 4 hours and 24 minutes. The magnetic field change value ΔTz of the background daily variation station was 49.52nT, which was greater than 30nT, and the change in magnetic anomaly intensity ΔA was 0.23nT, which was greater than the sensitivity of the magnetometer. Therefore, 16:16:02 can be used as the end point t2 of the continuous change period of the magnetic field. Using the magnetic field values at the anomaly and background daily variation stations at times t1 and t2, we calculated the F values at these times to be 0.50868 and 0.50891, respectively, and the Q values to be 0.96589 and 0.96498, respectively. Therefore, the residual magnetization of this anomaly is slightly smaller than the induced magnetization, suggesting that magnetite is the likely source of the magnetic anomaly, consistent with the exploration results.

[0114] like Figure 8 As shown in the figure, the magnetic anomaly caused by the potential iron ore in Houzhuang was discovered by aeromagnetic survey in 1979. The anomaly intensity was 1800nT at a flight altitude of 45m. It has superimposed anomaly characteristics, sharp peaks, and large gradients, which are the general characteristics of magnetic anomalies caused by magnetite. The physical property measurement results of Jinling area show that the magnetic susceptibility κ(×4π×10 -5 SI) magnetite 175000 (25000~450000), diorite 500 (0~7000), residual magnetization Mr (×10 -3 A / m) Magnetite 3630 ~ 7300, diorite 0 ~ 2940, diorite Q value is generally > 1, magnetite Q value is generally < 1. At that time, it was inferred that the anomaly source was magnetite. Later, drilling discovered skarn-type iron ore bodies with a burial depth of 124 ~ 444m. Figure 2 As shown in the figure, an abnormal daily variation station was set up in the negative value area on the northwest side of the magnetic anomaly. Since the positive magnetic anomaly area is in the factory area, an abnormal daily variation station could not be set up there. The magnetic anomaly ΔT value at the abnormal daily variation station is -183nT. Figure 8As shown, the magnetic field values of the abnormal daily variation station and the background daily variation station at different times were measured. By calculation, the probabilities of noise in the magnetic field values of the abnormal daily variation station and the background daily variation station at 12:54:02 were 0.00000 and 0.00761, respectively, which can be used as the starting point t1 of the continuous change period of the magnetic field; the probabilities of noise in the magnetic field values at 15:50:02 were 0.97125 and 2.19512, respectively, and the continuous change time was 2 hours and 56 minutes. The magnetic field change value ΔTz of the background daily variation station was 33.01nT, which was greater than 30nT, and the change in magnetic anomaly intensity ΔA was 0.11nT, which was greater than the sensitivity of the magnetometer. Therefore, 15:50:02 can be used as the end point t2 of the continuous change period of the magnetic field. Using the magnetic field values at the anomaly and background daily variation stations at times t1 and t2, we calculated the F values at these times to be 0.95597 and 0.95599, respectively, and the Q values to be 0.04606 and 0.04603, respectively. Therefore, the residual magnetization of this anomaly is much smaller than the induced magnetization, and the source of the magnetic anomaly is likely magnetite, which is consistent with the exploration results.

[0115] Example 2:

[0116] A device for measuring magnetic anomalies in iron ore, such as Figure 9 As shown, the equipment includes:

[0117] one or more processors;

[0118] A storage device for storing one or more programs, when the one or more programs are executed by the one or more processors, enables the one or more processors to implement the method for measuring magnetic anomalies of iron ore as described in any one of the first embodiments.

[0119] Figure 9 This is a schematic diagram of the equipment structure for measuring magnetic anomalies in iron ore provided in Example 2. Figure 9 A block diagram of an exemplary apparatus for measuring magnetic anomalies in iron ore suitable for implementing an embodiment of the present invention is shown. Figure 9 The device for measuring magnetic anomalies in iron ore shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present invention.

[0120] like Figure 9 As shown, the device for measuring magnetic anomalies in iron ore is presented as a general device. Components of the device for measuring magnetic anomalies in iron ore may include, but are not limited to, one or more processors or processing units, memory, and a bus connecting different system components (including the memory and processing units).

[0121] The term "bus" refers to one or more of several types of bus structures, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, a processor, or a local bus using any of a variety of bus architectures. Examples of these architectures include, but are not limited to, the Industry Standard Architecture (ISA) bus, the Micro Channel Architecture (MAC) bus, the Enhanced ISA bus, the Video Electronics Standards Association (VESA) local bus, and the Peripheral Component Interconnect (PCI) bus.

[0122] The device for measuring magnetic anomalies in iron ore typically includes a variety of computer system readable media. These media can be any available media that can be accessed by the device for correcting the intelligent logging interpretation model, including volatile and non-volatile media, removable and non-removable media.

[0123] The memory may include computer system readable media in the form of volatile memory, such as random access memory (RAM) 30 and / or cache memory. The apparatus for measuring magnetic anomalies in iron ore may further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, the storage system may be used to read and write non-removable, non-volatile magnetic media ( Figure 9 Not shown, often called a "hard drive"). Although Figure 9 Not shown, a disk drive for reading and writing to a removable non-volatile disk (e.g., a "floppy disk"), and an optical drive for reading and writing to a removable non-volatile optical disk (e.g., a CD-ROM, DVD-ROM, or other optical medium) may be provided. In these cases, each drive may be connected to the bus via one or more data medium interfaces. The memory may include at least one program product having a set (e.g., at least one) of program modules configured to perform the functions of various embodiments of the present invention.

[0124] A program / utility having a set (at least one) of program modules, which may be stored, for example, in a memory, includes, but is not limited to, an operating system, one or more application programs, other program modules, and program data, each of which, or some combination thereof, may include an implementation of a network environment. The program modules generally implement the functions and / or methods of the embodiments described herein.

[0125] The device for measuring the magnetic anomaly of iron ore may also communicate with one or more external devices (such as keyboards, pointing devices, displays, etc.), and may also communicate with one or more devices that enable a user to interact with the device for measuring the magnetic anomaly of iron ore, and / or communicate with any device that enables the device for measuring the magnetic anomaly of iron ore to communicate with one or more other devices (such as a network card, a modem, etc.). Such communication may be performed through an input / output (I / O) interface. In addition, the device for correcting the intelligent logging interpretation model may also communicate with one or more networks (such as a local area network (LAN), a wide area network (WAN), and / or a public network, such as the Internet) through a network adapter. Figure 9 As shown, the network adapter communicates with other modules of the iron ore magnetic anomaly measurement device via a bus. It should be understood that, although not shown in the figure, other hardware and / or software modules may be used in conjunction with the iron ore magnetic anomaly measurement device, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems.

[0126] The processing unit executes various functional applications and data processing by running programs stored in the memory, such as implementing the method for determining the magnetic anomaly of iron ore provided in any embodiment of the present invention. That is, a potential iron ore magnetic anomaly area is selected in a volcanic rock area or a surrounding rock Q value greater than 1 and an iron ore Q value less than 1; an abnormal daily variation station and a background daily variation station are established inside and outside the potential iron ore magnetic anomaly area, respectively, and the first magnetic daily variation data of the abnormal daily variation station and the second magnetic daily variation data of the background daily variation station are measured and recorded, and the noise probability contained in the first magnetic daily variation data and the second magnetic daily variation data is calculated; a period of continuous magnetic field variation in which the noise probability is lower than a preset threshold is selected, the starting point and end point of the period of continuous magnetic field variation are extracted, and the magnetic anomaly intensity change, the normalized magnetic anomaly intensity change F value, and the Q value of the magnetic anomaly source are calculated; when the normalized magnetic anomaly intensity change F value is greater than 0.5 and the Q value of the magnetic anomaly source in the potential iron ore magnetic anomaly area is less than 1, it is determined that the potential iron ore magnetic anomaly is caused by magnetite.

[0127] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for measuring magnetic anomaly in iron ore, characterized in that: The method includes: Selecting a potential iron ore-induced magnetic anomaly area in a volcanic rock area or in a mineral concentration area where the Q value of the surrounding rock is greater than 1 and the Q value of the iron ore is less than 1; Respectively establishing an anomaly diurnal variation station and a background diurnal variation station inside and outside the potential iron ore-induced magnetic anomaly area, measuring and recording the first magnetic diurnal variation data of the anomaly diurnal variation station and the second magnetic diurnal variation data of the background diurnal variation station, and simultaneously calculating the noise probability included in the first magnetic diurnal variation data and the second magnetic diurnal variation data; Selecting a magnetic field continuously changing period with the noise probability lower than a preset threshold, extracting the starting point and the ending point during the magnetic field continuous change period, and calculating the magnetic anomaly intensity change amount ΔA, the normalized magnetic anomaly intensity change F value, and the Q value of the magnetic anomaly source; When the normalized magnetic anomaly intensity change F value is greater than 0.5 and the Q value of the magnetic anomaly source in the potential iron ore-induced magnetic anomaly area is less than 1, determining that the potential iron ore-induced magnetic anomaly is caused by magnetite.

2. The method for measuring magnetic anomaly of iron ore according to claim 1, characterized in that: The anomaly diurnal variation station is located in the area from the maximum value of the potential iron ore-induced magnetic anomaly to the maximum value / 2 or from the minimum value to the minimum value / 2, and the distance between the background diurnal variation station and the potential iron ore-induced magnetic anomaly is less than or equal to 30 km.

3. The method for measuring magnetic anomaly of iron ore according to claim 1, characterized in that: The method for calculating the noise probability included in the first magnetic diurnal variation data and the second magnetic diurnal variation data includes: Noise probability P t ,and: in, Where: D t It is the distance from the magnetic field data at a certain time t of the background daily variation station or the abnormal daily variation station to the straight line containing the magnetic field data at time t-1 and time t+1. H is the geomagnetic field T or one of the three magnetic components N, E, and V of the geomagnetic field.

4. The method for measuring magnetic anomaly of iron ore according to claim 1, characterized in that: The method for selecting the magnetic field continuously changing period with the noise probability lower than a preset threshold includes: The magnetic field continuously changing period is when the first magnetic diurnal variation data of the anomaly diurnal variation station and the second magnetic diurnal variation data of the background diurnal variation station increase or decrease synchronously, and the noise probability is lower than 5%.

5. The method for measuring magnetic anomaly of iron ore according to claim 1, characterized in that: The method for extracting the starting point and the ending point during the magnetic field continuous change period includes: During the magnetic field continuous change period, the static magnetic day maintenance time is greater than 2 hours and the magnetic field diurnal variation amount of the background diurnal variation station is greater than 30 nT, and the magnetic field diurnal variation amount during a magnetic storm or a strong magnetic disturbance day is greater than 50 nT.

6. The method for measuring magnetic anomaly of iron ore according to claim 1, characterized in that: The method for calculating the magnetic anomaly intensity change amount ΔA according to the first magnetic diurnal variation data and the second magnetic diurnal variation data for respectively determining the starting point and the ending point according to the records includes: ΔA=ΔT t2 -ΔT t1 Where, ΔT ti =Ty ti -Tz ti ,i∈(1,2) Where: ΔT t1 Indicates the magnetic anomaly value at the starting point, ΔT t2 Indicates the magnetic anomaly value at the end point, Ty t2 Indicates the end point magnetic field value of the abnormal daily variation station; Ty t1 Indicates the starting point magnetic field value of the abnormal daily variation station; Tz t2 Indicates the end point magnetic field value of the background daily variation station; Tz t1 Indicates the starting point magnetic field value of the background daily variation station.

7. The method for measuring magnetic anomaly of iron ore according to claim 6, characterized in that: The method for extracting the starting point and the ending point during the magnetic field continuous change period and calculating the magnetic anomaly intensity change amount ΔA further includes: ΔA=(Mi t2 -Mi t1 )×S; in: Among them, Mi t1 is the induced magnetization intensity at time t1, Mi t2 is the induced magnetization intensity at time t2, S is the spatial information, is the unit vector of the magnetic moment at the magnetic dipole Q point, is the unit vector of the Earth's magnetic field, is the unit vector of the distance from the magnetic dipole Q point to the abnormal daily variation station or the background daily variation station, r is the distance from the magnetic dipole Q point to the abnormal daily variation station or the background daily variation station, v is the volume of the magnetic anomaly source, and μ0 is the vacuum magnetic permeability.

8. The method for measuring magnetic anomaly of iron ore according to claim 7, characterized in that: The first and second daily magnetic variation data of the starting and ending points are determined according to the records, and the normalized magnetic anomaly intensity change F is calculated. t The value methods include: When Mi << Mr, Ft ≈ 0; When Mi>>Mr, If Mi≈Mr, then Where κ is the magnetic susceptibility, μ0 is the vacuum permeability, and Mr is the remanent magnetization.

9. The method for measuring magnetic anomaly of iron ore according to claim 8, characterized in that: The method for calculating the Q value of the magnetic anomaly source according to the first magnetic diurnal variation data and the second magnetic diurnal variation data for respectively determining the starting point and the ending point according to the records includes:

10. An apparatus for measuring magnetic anomaly in iron ore, characterized in that the apparatus Includes: One or more processors; A storage device for storing one or more programs, which when executed by the one or more processors, cause the one or more processors to implement the method for determining iron ore-induced magnetic anomalies as described in any one of claims 1-9.

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