Method and equipment for determining ore-induced magnetism anomaly of iron ore

Abstract

The invention discloses a method and equipment for determining iron ore magnetism-induced anomaly. The method comprises the following steps: selecting a potential iron ore magnetism-induced anomaly region in a volcanic rock region or an ore concentration region with 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 in and out of the potential iron ore induced magnetism anomaly area respectively, first magnetic daily variation data of the abnormal daily variation station and second magnetic daily variation data of the background daily variation station are measured and recorded, and noise probabilities contained in the first magnetic daily variation data and the second magnetic daily variation data are calculated at the same time; selecting a magnetic field continuous change period of which the noise probability is lower than a preset threshold value, extracting a starting point and an ending point of the magnetic field continuous change period, and calculating to obtain a magnetic anomaly intensity variable quantity, a normalized magnetic anomaly intensity change F value and a Q value of a magnetic anomaly source; when the normalized magnetic anomaly intensity change F value is larger than 0.5 and the Q value of the magnetic anomaly source of the potential iron ore induced magnetic anomaly area is smaller than 1, it is judged that potential iron ore induced magnetic anomaly is caused by magnetite.

Description

Technical Field

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

[0002] Most of my country's iron ores have the characteristics of strong magnetism. Iron ore bodies generally cause strong magnetic anomalies. Magnetic methods have played a significant role in the prospecting, exploration and research of iron ore. Almost 90% of magnetites are discovered based on magnetic anomalies. At present, more than 90,000 magnetic anomalies have been discovered by aeromagnetic survey alone, and only more than 10,000 have been verified, accounting for only about 15% of the discovered anomalies. Although many iron ore bodies show magnetic anomalies, magnetic anomalies are not necessarily caused by iron ore bodies. Surface mines have basically been discovered now, and prospecting work needs to advance to hidden areas or even deep areas. However, except for drilling, there is no technical method that can directly crack whether magnetic anomalies have the potential to find iron ore.

[0003] At present, magnetic detection is a commonly used method to study 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, magnetites, polymetallic ores containing magnetites, etc. This work is mainly determined after comprehensive analysis based on the characteristics of magnetic anomalies and their geological environment and mineralization conditions, the information and magnetic characteristics of the discovered strata, rocks, ore bodies, etc., combined with other geophysical and geochemical anomalies. This research method is completely a logical reasoning from the known to the unknown, with a lot of uncertainty and may be different from the actual situation. The correctness of the inference results can only be verified by drilling. However, the cost of drilling is very high, and it is difficult to invest a lot of drilling work to solve the problem of whether magnetic anomalies have the potential to find 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 view of the above defects or improvement needs of the prior art, the present invention provides a method and equipment for measuring the magnetic anomaly of iron ore, the purpose of which is to quickly determine whether the potential magnetic anomaly of iron ore is caused by an iron ore body, thereby solving the technical problem that currently only drilling actual survey can be carried out.

[0006] To achieve the above object, according to one aspect of the present invention, a method for measuring magnetic anomaly of 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 in 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 calculating the noise probability contained in the first magnetic daily variation data and the second magnetic daily 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 the 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 value to the maximum value / 2 or from the minimum value to the minimum value / 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 magnetic diurnal variation data and the second magnetic diurnal variation data comprises:

[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 where the magnetic field data at time t-1 and time t+1 are located. 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 comprises:

[0020] During the period of continuous magnetic field change, 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 30 n T, the daily variation of the magnetic field on a storm or strong magnetic disturbance day is greater than 50 n T.

[0021] Preferably, the method of calculating the magnetic anomaly intensity variation ΔA based on the first magnetic daily variation data and the second magnetic daily variation data of the starting point and the end point 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 during the continuous change of the magnetic field and calculating the change amount ΔA of the magnetic anomaly intensity also 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 magnetic moment unit vector of 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 point Q to the abnormal daily variation station or the background daily variation station, r is the distance from the magnetic dipole point Q 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 according to the first magnetic daily variation data and the second magnetic daily variation data of the starting point and the end point respectively determined by recording comprises:

[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 measuring iron ore-induced magnetic anomalies, 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 measuring iron ore-induced magnetic anomalies as described in the first aspect.

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

[0041] The method for measuring iron ore-induced magnetic anomalies provided by the present invention can quickly determine whether the potential iron 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 drawings required to be used in the embodiments of the present invention will be briefly introduced below. 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 according to these drawings without creative efforts.

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

[0044] Figure 2The aeromagnetic ΔT contour line plane map and the potential iron ore induced magnetic anomaly and daily variation station distribution map provided in the first embodiment;

[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 the present invention;

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

[0051] Fig. 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 purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain 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 can be combined with each other as long as they do not conflict with each other.

[0053] Embodiment 1

[0054] This embodiment provides a method for measuring magnetic anomaly of 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 the same in the same ore cluster area, but different in different ore cluster areas. In some ore cluster areas, the Q value of the surrounding rock is greater than the Q value of the iron ore, while in some ore cluster areas, 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 (theoretically, it has a similar change law to the Q value) and the Q value can be used to determine whether the potential iron ore magnetic anomaly is caused by iron ore magnetic anomaly, that is, magnetite.

[0057] S102: Establish an abnormal daily variation station and a background daily variation station respectively inside 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-induced magnetic anomaly is located in the iron ore mineralization zone, which has the geological, structural and other elements required for the formation of iron ore, and there are iron ore mineral production nearby, and the magnetic anomaly intensity and gradient are relatively large.

[0059] like Figure 2 As shown, the potential iron ore magnetic anomaly position, as well as the pre-selected abnormal daily variation station position and the background daily variation station position are marked on the aeromagnetic map. The abnormal daily variation station position and the background daily variation station position are determined by field survey. The abnormal daily variation station should be located in the area from the maximum value to the maximum value / 2 or from the minimum value to the minimum value / 2 of the potential iron ore magnetic anomaly, with little human interference on the surface and relatively open terrain (non-pits); the background daily variation station should be less than 30km away from the potential iron ore magnetic anomaly, with a calm magnetic field, small gradient (magnetic field gradient <1nT / 2m), little human interference (the distance from buildings should be greater than 15m, away from traffic lines, transmission 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 devices used are tested to ensure that they are in the correct state, and different devices 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, 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 of the daily variation station at different times, 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 of the daily variation station at different times, the probability P of noise in the magnetic daily 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 being included in the 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 where the magnetic field data at time t-1 and time t+1 are located. 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 measured 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: Select a period of continuous magnetic field change in which the noise probability is lower than a preset threshold, extract the starting point and the end point of the period of continuous magnetic field change, and calculate 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 anomalies caused by the residual magnetization intensity Mr and the anomalies caused by the induced magnetization intensity Mi. The former is retained after the rock or ore is magnetized by the geomagnetic field at that time when it was generated, 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, an abnormal daily variation station and a background daily variation station were established inside and outside the potential iron ore magnetic anomaly area, and the first magnetic daily variation magnetic field value Ty of the abnormal daily variation station at each time during a period of time was measured. t The second magnetic daily variation magnetic field value Tz of the background daily variation station t , calculate the magnetic field difference ΔT of the two diurnal variation measuring 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 -Tz t

[0073] Since the geomagnetic field changes very slowly during the solar quiet day, but even the magnetic field changes during the magnetic storm are very small compared to the geomagnetic field strength (generally greater than 50000nT), 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] ,but

[0082] ΔT t =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 magnetic moment unit vector of 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 point Q to the abnormal daily variation station or the background daily variation station, r is the distance from the magnetic dipole point Q 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 the Q point. 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, which characterizes the physical characteristics of the magnetic anomaly source in the formula and belongs to the detection object. In this embodiment, the magnetization intensity does not need to know the specific value, but is only a transition variable.

[0087] The magnetic field strength at time t is observed by the magnetometers installed at the abnormal daily variation station and the background daily variation station. The magnetic field strength needs to be measured and is a numerical value that measures the magnitude of the 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] Selecting a time period during which the magnetic field continues to increase or decrease, in combination with the embodiment of the present invention, there is also a preferred implementation scheme. Specifically, the method for extracting the starting point and the end point during the period during which the magnetic field continues to change includes:

[0090] During the period when the magnetic field continuously increases or decreases, the static magnetic day lasts for more than 2 hours and the magnetic daily variation of the background daily variation station is greater than 30 nT, and the magnetic daily variation of the magnetic storm or strong magnetic disturbance day is greater than 50 nT; the probability of noise in the first magnetic field value and the second magnetic field value at the starting point and the ending point 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. Therefore, quantitative evaluation cannot be carried out. For this reason, 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 vacuum permeability, and Mr is the remanent magnetization intensity.

[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 Koenigsberg ratio, is the ratio of the residual magnetization Mr to the induced magnetization Mi. It can be used to determine the nature of the source of the magnetic anomaly. For example, the Q value of magnetite in my country is generally less than 1, while the Q value of strongly magnetic igneous rocks is generally greater than 1. This can be used to determine whether the magnetic anomaly is caused by iron ore. At present, the Q value of the rock or ore is generally obtained by collecting a large number of rock or ore samples and measuring their Mr and Mi indoors. However, the Q value obtained by this method is only statistically significant and can be used to guide research work, but cannot be directly used in geological and mineral exploration.

[0103] In the first embodiment, the method for calculating the Q value of the magnetic anomaly source according to the first magnetic daily variation data and the second magnetic daily variation data of the starting point and the end point respectively determined by recording includes:

[0104] Defined by the Q value:

[0105]

[0106] Mr is the residual magnetization, Mi t is the induced magnetization intensity at time t. 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 the induced magnetization intensity Mi is generally dominant in my country's magnetite, 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 cluster 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 in Mengbaizhuang was discovered by aeromagnetic survey in 1959. The anomaly intensity is as high as 4000nT, with a sharp peak and a large gradient, which has the general characteristics of magnetic anomalies caused by magnetite. The buried depth of the magnetic body: 370m by tangent method and 350m by different height methods. The magnetic susceptibility of andesite in the area can reach 20000×4π×10 -5 SI, but it varies from time to time; the magnetic susceptibility of gabbro is only 2000×4π×10 -5SI, 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 drilling verification had not been 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 why it was not set 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 magnetic field difference between the abnormal daily variation station and the background daily variation station). Figure 5 As shown in the figure, the magnetic field values ​​of the abnormal daily variation station and the background daily variation station at different times in the magnetic anomaly area of ​​the potential iron ore in Mengbaizhuang were measured. By calculation, the probability of noise in the magnetic field values ​​of the abnormal daily variation station and the background daily variation station at 12:34:02 was 0.01905 and 0.00222, respectively, which can be used as the starting point t1 of the continuous change of the magnetic field; the probability of noise in the magnetic field values ​​at 16:14:02 was 0.11983 and 0.11317, respectively, and the continuous change time was 3 hours and 40 minutes. The magnetic field change value ΔTz of the background daily variation station was 34.48nT, which was greater than 30nT, and the change in magnetic anomaly intensity ΔA was 0.25nT, which was greater than the sensitivity of the magnetometer. Therefore, 16:14:02 can be used as the end point t2 of the continuous change of the magnetic field. Using the magnetic field values ​​of the abnormal daily variation station and the background daily variation station at t1 and t2, the F values ​​at these two moments were calculated to be 0.49, and the Q values ​​were 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 of Wangwangzhuang potential iron ore was discovered by aeromagnetic survey in 1979. The anomaly intensity is generally 1500nT at a flight altitude of 45m, and is accompanied by a -500nT anomaly in the north. It has the characteristics of superimposed anomalies, sharp peaks, and large gradients, and has the general characteristics of magnetic anomalies caused by magnetite. The physical property measurement results of Jinling area, magnetic susceptibility κ (×4π×10 -5 SI) magnetite 175000 (25000~450000), diorite 500 (0~7000), residual magnetization intensity 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 abnormal source was magnetite, and later drilling discovered skarn-type iron ore bodies, with a burial depth of about 400m. Figure 2As shown in the figure, an abnormal daily variation station was set up in the gradient zone to the 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 here. The magnetic anomaly ΔT value at the abnormal daily variation station is 825nT (the magnetic field difference between the abnormal daily variation station and the background daily variation station). Figure 6 As shown, the magnetic field values ​​of the abnormal daily variation station and the background daily variation station at different times were measured. Through 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 ​​of the abnormal daily variation station and the background daily variation station at t1 and t2, the F values ​​at these two moments are calculated to be 0.88211 and 0.88218, and the Q values ​​are 0.13365 and 0.13356, respectively. Therefore, the residual magnetization intensity of the anomaly is much smaller than the induced magnetization intensity, and the possibility that the source of the magnetic anomaly is magnetite is very high, which is 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 a flight altitude of 45m. It has the characteristics of superimposed anomalies, sharp peaks, and large gradients, and has the general characteristics of magnetic anomalies caused by magnetite. The physical property measurement results of Jinling area, magnetic susceptibility κ (×4π×10 -5 SI) magnetite 175000 (25000~450000), diorite 500 (0~7000), residual magnetization intensity 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 on the southwest side 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 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. Through 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 ​​of the abnormal daily variation station and the background daily variation station at t1 and t2, the F values ​​at these two moments are calculated to be 0.50868 and 0.50891, and the Q values ​​are 0.96589 and 0.96498, respectively. Therefore, the residual magnetization intensity of the anomaly is slightly smaller than the induced magnetization intensity, and the possibility that the source of the magnetic anomaly is magnetite is high, which is 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 the characteristics of superimposed anomalies, sharp peaks, and large gradients, and has the general characteristics of magnetic anomalies caused by magnetite. The physical property measurement results in Jinling area, magnetic susceptibility κ (×4π×10 -5 SI) magnetite 175000 (25000~450000), diorite 500 (0~7000), residual magnetization intensity 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 abnormal source was magnetite, and 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 value area of ​​the magnetic anomaly 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. Through calculation, the probabilities of noise existing 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 existing 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 ​​of the abnormal daily variation station and the background daily variation station at t1 and t2, the F values ​​at these two moments are calculated to be 0.95597 and 0.95599, and the Q values ​​are 0.04606 and 0.04603, respectively. Therefore, the residual magnetization intensity of the anomaly is much smaller than the induced magnetization intensity, and the possibility that the source of the magnetic anomaly is magnetite is very high, which is consistent with the exploration results.

[0115] Embodiment 2:

[0116] A device for measuring magnetic anomalies in iron ore, such as Fig. 9 As shown, the device 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, the one or more processors implement the method for measuring magnetic anomalies of iron ore as described in any one of the first embodiments.

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

[0120] like Fig. 9 As shown, the device for measuring magnetic anomaly of iron ore is presented in the form of a general device. The components of the device for measuring magnetic anomaly of 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 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. For example, 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 anomaly of 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 determining magnetic anomalies of 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 ( Fig. 9 not shown, usually called a "hard drive"). Although Fig. 9 Not shown, a disk drive for reading and writing to a removable non-volatile disk (e.g., a "floppy disk"), and an optical disk 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 that are configured to perform the functions of the embodiments of the present invention.

[0124] A program / utility having a set (at least one) of program modules may be stored, for example, in a memory, such program modules including but not limited to an operating system, one or more application programs, other program modules, and program data, each of which or some combination may include an implementation of a network environment. The program modules generally perform 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. Furthermore, 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. Fig. 9 As shown, the network adapter communicates with other modules of the device for measuring magnetic anomalies of iron ore through the bus. It should be understood that, although not shown in the figure, other hardware and / or software modules can be used in conjunction with the device for measuring magnetic anomalies of iron ore, including but not limited to: microcode, device driver, redundant processing unit, external disk drive array, RAID system, tape drive, and data backup storage system, etc.

[0126] The processing unit executes various functional applications and data processing by running the program stored in the memory, such as realizing the method for determining the magnetic anomaly of iron ore provided by any embodiment of the present invention. That is: select a potential magnetic anomaly area of ​​iron ore in a volcanic rock area or a surrounding rock Q value greater than 1 and an iron ore Q value less than 1; establish an abnormal daily change station and a background daily change station in and outside the potential magnetic anomaly area of ​​iron ore, respectively, measure and record the first magnetic daily change data of the abnormal daily change station and the second magnetic daily change data of the background daily change station, and calculate the noise probability contained in the first magnetic daily change data and the second magnetic daily change data; select a magnetic field continuous change period with a noise probability lower than a preset threshold, extract the starting point and end point during the continuous change of the magnetic field, and calculate the change in magnetic anomaly intensity, 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 magnetic anomaly area is less than 1, it is judged that the magnetic anomaly of the potential iron ore 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 protection scope of the present invention.

Claims

1. A method for measuring magnetic anomaly of 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 mineralization 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 to half of the maximum value or from the minimum value to half of the minimum value of the potential iron ore-induced magnetic anomaly, 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(P t ∈Pz t , Py 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 where the magnetic field data at time t-1 and time t+1 are located. 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, the magnetic field diurnal variation change amount of the background diurnal variation station is greater than 30 nT, and the magnetic field diurnal variation change 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 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 t is the induced magnetization intensity at time t, S is the spatial information, is the magnetic moment unit vector of 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 point Q to the abnormal daily variation station or the background daily variation station, r is the distance from the magnetic dipole point Q 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 method for calculating the normalized magnetic anomaly intensity change F value according to the first magnetic diurnal variation data and the second magnetic diurnal variation data respectively determining the starting point and the ending point according to the records includes: 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 1, 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 respectively determining the starting point and the ending point according to the records includes:

10. A device for measuring magnetic anomaly of iron ore, characterized in that the device 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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