Equipment for measuring ore in mine benches.

Abstract

An apparatus for measuring ore in a mine ore bench or ore stockpile is disclosed, the apparatus comprising: a mobile platform defining a platform area, wherein the mobile platform is positionable on or above the mine ore bench or ore stockpile; and at least one magnetic resonance (MR) sensor included in the mobile platform. The MR sensor includes a main loop and a drive loop located above the main loop. A magnetic resonance sensor control system is provided and configured to control at least one of the following: the positioning of the at least one MR sensor relative to the platform area and / or the mine ore bench or ore stockpile; the positioning of elements included in the MR sensor relative to each other; the electromagnetic suppression characteristics of the at least one MR sensor; and / or the sensitivity of the at least one MR sensor varying with the distance of the sensor from the mine ore bench or ore stockpile.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Australian Provisional Patent Application No. 2019904928, filed on 24 December 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to an apparatus and method for measuring ore in a mine ore bench or orestockpile. Background Technology

[0004] During mining, ore can be extracted underground or in an open-pit mine. In most open-pit mines, ore is extracted from mine benches. Mine benches are roughly horizontal surfaces formed on the bottom of the mine to prepare for blasting the rock and subsequent extraction.

[0005] To extract ore, blasting hole drills are used to drill ore benches, creating predefined blasting hole patterns within them. To break up the solid rock within the ore benches, the benches are blasted by detonating explosives placed in the blasting holes. In hard rock mining, the depth of the benches to be blasted is typically 10 to 15 meters, and the area of ​​the benches can span hundreds of square meters. After blasting, excavating machinery (such as single-bucket excavators) is used to load the blasted rock into the next transport stage, which typically includes trucks or other types of loaders or transport vehicles.

[0006] There are also mines where ore can be extracted from relatively flat, un-blasted horizontal surfaces using different mining methods. For example, ore can be mined using continuous mining equipment that traverses relatively flat ore areas and cuts away relatively shallow ore layers using integrated cutting tools. This process is repeated to gradually strip the ore from the relatively thinner layers. For the purposes of this specification, a flat area subjected to, for example, continuous mining can also be considered as a type of mine bench.

[0007] Prior to blasting, there is an opportunity to measure the physical, chemical, or mineralogical properties of the ore in the bench, such as the elemental composition or grade (concentration) of the ore. Measurements can be taken for various purposes. For example, the measurement data can be used to verify information or to add information to a mine section model.

[0008] A mine section model is a spatial discrete representation of ore parameters (such as ore grade) in a portion of a ore deposit that is planned to be mined (such as a section of a bench). In a section model, ore parameters are assigned to individual voxels of the ore. The size of each voxel, or "mine section," varies depending on the type of mining and deposit, but a typical size for a large open-pit mine can be 10,000 tons of ore. A mine bench can consist of multiple mine sections.

[0009] Measurement data can also be used to optimize blasting methods, for example, based on the measured rock hardness or grade. Explosive loads can be adjusted throughout the blast hole pattern or even within a single blast hole based on the measurement data. This is done to preferentially fracture or crush rock in specific areas within a bench. This approach can be used to improve the recovery of high-grade materials in downstream processes or to achieve selective mining based on grade-grain size correlations.

[0010] In addition to mine benches, the physical, chemical, or mineralogical properties of ore stockpiles can be measured. A stockpile typically represents a very large, long-term accumulation of blasted ore, and may have a relatively flat area suitable for measurement. Ore stockpiles may consist of low-grade ore that is either uneconomical to extract or unsuitable for further processing. However, it is known that stockpiles may not have heterogeneous ore distributions, and relatively high-grade, economically viable mining areas may exist within stockpiles, for example, due to accidental or unavoidable placement there. The motivation for measuring stockpiles is to characterize the distribution of elemental or mineral grades so that selective recovery of high-grade areas can be made. Currently, stockpile analysis is generally less systematic than bench analysis, resulting in a lack of detailed grade distribution within the stockpile.

[0011] Currently known methods that can be used to measure ore properties include:

[0012] a. Drill cuttings from the blast hole drilling process can be sampled from the drill bit left on the bench after drilling is completed and identified to determine grade or mineralogical properties. Sampling can be performed manually before the explosives are loaded into the blast hole or automatically using a robot or semi-automatic sampler that traverses the drilling bench.

[0013] b. Sensors can be used below the blast hole to record the characteristics of the ore within the borehole wall. These include, for example, nuclear or X-ray logging tools.

[0014] c. Sensors can be deployed on the drill pipe to monitor ore properties, such as ore hardness, in real time during the drilling process.

[0015] d. Optical or other methods may be used to scan the surface of the mine steps to determine the mineralogical aspects of the ore.

[0016] Generally, measurements involving sensors are preferably performed using bulk sensing methods, which have penetrating sensing capabilities beyond the rock surface. Surface-based techniques can potentially provide a large amount of poor representation of ores due to the formation of dust layers, drilling mud stains, or surface moisture films.

[0017] The methods listed above have known limitations. For example, these limitations include poor sampling statistics or low spatial resolution due to the analysis of a limited number of drill cuttings cones or holes. These limitations may arise from the constraints of the sampling or measurement intensity practically achievable on a drilling bench.

[0018] While literature exists relating to manual sampling and sensing methods used for drilling mine benches, instances of sensing mine benches prior to drilling are very rare. Seismic analysis can be used to identify faults or other structures within benches. Ground-penetrating radar can be used to measure the spatial properties of layers or features separated by mining areas with different electromagnetic properties (such as coal seams in coal mining). Reflectance spectroscopy can be used to infer the presence of selected minerals on the bench surface. However, these methods are generally not suitable for inferring the detailed distribution of mineral or elemental grades within mine benches.

[0019] Any discussion of documents, laws, materials, devices, articles of manufacture, etc. included in this specification shall not be construed as an admission that any or all of these matters form part of the prior art or are common general knowledge in the field relating to this disclosure, simply because they exist prior to the priority date of each of the appended claims. Summary of the Invention

[0020] According to one aspect of this disclosure, an apparatus is provided for measuring ore in a mine bench or ore stockpile, the apparatus comprising:

[0021] A mobile platform, defined by a platform area, wherein the mobile platform can be positioned on or above a mine ore bench or ore stockpile.

[0022] At least one magnetic resonance (MR) sensor is included in the mobile platform, the MR sensor comprising:

[0023] The main loop can be located in a platform area situated above or on the ore benches or ore stockpiles of a mine.

[0024] A drive loop is located above and electrically isolated from the main loop and magnetically coupled to the main loop, wherein a radio frequency (RF) transmitter can be coupled to the feed terminal of the drive loop to drive the RF drive current in the drive loop, and an RF receiver can be coupled to the drive loop to monitor the RF response current in the drive loop.

[0025] The device further includes:

[0026] A magnetic resonance sensor control system configured to control at least one of the following:

[0027] The location of at least one MR sensor relative to the platform area and / or mine ore steps or ore stockpile;

[0028] The positioning of the components included in an MR sensor relative to each other;

[0029] Electromagnetic suppression characteristics of at least one MR sensor; and / or

[0030] The sensitivity of at least one MR sensor varies with the distance of the sensor from the mine ore bench or ore stockpile.

[0031] In some embodiments, the main loop may include a plurality of conductive segments and capacitors positioned between the conductive segments. The capacitors may be evenly spaced along the main loop, and the capacitance of each capacitor may be substantially equal. In some embodiments, the capacitance of at least one capacitor in the main loop is adjustable. In some embodiments, the sensor control system is configured to adjust the capacitance of at least one capacitor in the main loop.

[0032] In some embodiments, the device further includes an impedance monitor to monitor the reactive impedance at the feed terminal of the drive loop. The sensor control system can be configured to adjust the capacitor based on the monitored reactive impedance. In some embodiments, the sensor control system can be configured to adjust the capacitor such that the reactive impedance at the feed terminal of the drive loop is at a target reactive impedance.

[0033] In some embodiments, the conductive segments and capacitors of the main loop may extend along the loop path, and in the cross-section, in a plane perpendicular to the loop path, the conductive segments may have a non-circular cross-sectional shape. In some embodiments, the non-circular shape may be a shape with a convex boundary and an opposing concave boundary. The convex boundary may be located radially outward of the main loop, and the concave boundary may be located radially inward of the main loop. In some embodiments, the non-circular shape may be crescent-shaped, kidney-shaped, or a crescent shape formed by two intersecting ellipses.

[0034] In any of the embodiments disclosed herein, the sensor control system may be configured to control at least one of the following: (i) the position and / or orientation of at least one MR sensor relative to a mine ore bench or ore stockpile; and (ii) the position and / or orientation of a drive loop relative to a main loop. For example, the sensor control system may be configured to control the movement of the entire MR sensor, or at least the main loop and drive loop of the MR sensor, such that they are closer to or further away from the mine ore bench or ore stockpile. Alternatively or concurrently, the sensor control system may be configured to control the movement of the main loop and drive loop to bring them closer to or further away from each other. To achieve the changes in movement and orientation, the device may include one or more motion actuators, such as linear actuators controlled by a motor, pneumatic, hydraulic, or otherwise.

[0035] The device may include an impedance monitor to monitor the resistive impedance at the feed terminal of the drive loop, and the sensor control system may be configured to adjust the position and / or orientation as generally described above based on the monitored resistive impedance. In some embodiments, the sensor control system may be adapted to adjust the position and / or orientation such that the resistive impedance at the feed terminal of the drive loop is at a target resistive impedance.

[0036] In some embodiments, the sensor control system may be configured to adjust the position and / or orientation of the MR sensor relative to a mine ore step or ore stockpile such that the resistive impedance at the feed terminal of the drive loop is within a predetermined resistive impedance range. In some embodiments, the sensor control system may be configured to subsequently adjust the position and / or orientation of the drive loop relative to the main loop such that the resistive impedance at the feed terminal of the drive loop is at a target resistive impedance.

[0037] In some embodiments, the device may further include a displacement monitor to monitor displacement (e.g., changes in position and / or orientation) between at least one MR sensor and a mine ore bench or ore stockpile. The sensor control system may be configured to adjust the position and / or orientation of the MR sensor based on the monitored displacement. In some embodiments, the sensor control system may adjust the position and / or orientation of the MR sensor based on the monitored displacement to maintain a fixed interval between the mine ore bench or ore stockpile and the main loop.

[0038] In any of the embodiments disclosed herein, the device may include a reflector positioned above the main loop, the reflector being configured to reduce upward radiation and magnetic near-field from the mine ore steps or ore stockpile.

[0039] In any of the embodiments disclosed herein, the device may include a passive loop located above or flush with the main loop (in the plane of the main loop). The passive loop may be configured to suppress external electromagnetic interference in the main loop.

[0040] In some implementations, the reflector is located between the main loop and the passive loop.

[0041] In some implementations, the passive loop has a lumped capacitance impedance that can be adjusted by the sensor control system to optimize the suppression of external electromagnetic interference in the main loop.

[0042] In the embodiments disclosed herein, the device may further include a noise monitor to monitor the RF noise voltage at the feed terminal of the drive loop. In some embodiments, the sensor control system may be configured to adjust the lumped impedance of the passive loop capacitor based on the monitored RF noise voltage to minimize the RF noise voltage at the feed terminal of the drive loop.

[0043] In any of the embodiments disclosed herein, the device may further include a resistive loop magnetically coupled to the main loop and resistively terminated. The sensor control system may be configured to adjust the orientation of the resistive loop relative to the main loop. In some embodiments, the device may include an impedance monitor to monitor the resistive impedance at the feed terminal of the drive loop, and the sensor control system may be configured to adjust the orientation of the resistive loop relative to the main loop based on the monitored resistive impedance, such that the resistive impedance at the feed terminal of the drive loop is at a target resistive impedance.

[0044] In the embodiments disclosed herein, the device may further include an insert radially positioned within the main loop in the plane of the main loop. In some embodiments, the insert is an oblate spheroid.

[0045] In some embodiments, the mobile platform may include a chassis with wheels or sliders. In some embodiments, the mobile platform may be towed by a vehicle (including a continuous mining machine) and / or have a device for self-propulsion. For example, the mobile platform may be self-motorized. In some embodiments, the mobile platform may be an autonomous system programmed to mark predefined areas on the mine's ore benches.

[0046] In some embodiments, the sensor control system may be integrated into the mobile platform. Alternatively or additionally, the sensor control system or components thereof may be located in a separate structure that moves with the mobile platform. In some embodiments, the separate structure is tethered to establish a communication link between the sensor control system and the mobile platform. In some embodiments, the sensor control system may be fixed in a location in a separate structure at a convenient point on a mine ore bench and tethered to the mobile platform.

[0047] In some implementations, ore measurement may include the measurement of ore mineral content and / or ore grade.

[0048] In some embodiments, the device includes a platform control system. The platform control system can be configured to control the movement of the mobile platform on a mine ore bench or ore stockpile, enabling a portion of the mine ore bench or ore stockpile to move relatively through or be positioned within the platform area of ​​the mobile platform. In some embodiments, the platform control system can be configured to control the exchange of information between the device and one or more other components of the mine environment.

[0049] In another aspect of this disclosure, a method is provided for measuring ore in a mine ore bench or ore yard using equipment according to any of the embodiments disclosed herein.

[0050] As indicated, the sensor control system can be configured to control the sensitivity of at least one MR sensor as it varies with distance from the sensor to a mine ore bench or ore stockpile. The sensitivity of at least one MR sensor can be identified based on a “sensitivity distribution curve” for one or more RF pulse sequences applied to the MR sensor and for one or more associated analysis methods (masks), which represents the sensitivity of at least one MR sensor as it varies with distance from the sensor to the mine ore bench or ore stockpile.

[0051] Relatedly, in some embodiments, apparatus and methods are disclosed for determining one or more predetermined sensitivity distribution curves for an MR sensor based on one or more RF pulse sequences applied to it and one or more associated analytical methods (masks). Masks can be applied to the time-domain MR signal to preferentially target the responses at different depths of a mine ore bench or ore stockpile. For a specific mine ore bench or ore stockpile to be analyzed, weights can be applied to each measurement in the sensitivity distribution curves. For example, the sensor control system can use the weights from one or more sensitivity distribution curves to estimate the depth-dependent mineral concentration in the mine ore bench or ore stockpile.

[0052] For example, in one implementation, the sensor control system of the device can be configured as follows:

[0053] At least one RF pulse sequence is controlled to be applied to an MR sensor, and at least one correspondence analysis method is used to analyze the MR response signal from a mine ore bench or ore stockpile, wherein the at least one RF pulse sequence has a corresponding predetermined sensitivity distribution curve for its correspondence analysis method.

[0054] The analysis of the MR response signal is used to measure the weighted corresponding sensitivity distribution curve; and

[0055] Sensitivity distribution curves are used to weight the mineral concentrations that vary with depth in mine ore benches or ore stockpiles.

[0056] In some implementations, apparatus and methods are disclosed that utilize or include:

[0057] i. Determine a first predetermined sensitivity distribution curve for the MR sensor based on a first RF pulse sequence applied to the MR sensor and a first associated analysis method (mask);

[0058] ii. For one or more additional RF pulse sequences applied to the MR sensor and one or more associated analytical methods (masks), determine one or more additional predetermined sensitivity distribution profiles for the MR sensor;

[0059] iii. The first RF pulse sequence is provided to the MR sensor and the first associated analysis method is used to analyze the obtained first MR response signal from the mine ore step or ore stockpile to measure the first sensitivity distribution curve weighted by the first sensitivity distribution curve.

[0060] iv. Provide one or more additional RF pulse sequences to the MR sensor and use one or more additional associated analytical methods to analyze one or more additional MR response signals obtained from the mine ore step or ore stockpile to measure one or more additional sensitivity distribution curves weighted by one or more additional sensitivity distribution curves.

[0061] v. Weight the sensitivity distribution curves measured in steps (iii) and (iv) to create a preferred spatially weighted sensitivity distribution curve; and

[0062] vi. Use the preferred spatial sensitivity distribution curve obtained in step (v) to estimate the depth-dependent mineral concentration in the mine ore bench or ore stockpile.

[0063] For example, in one implementation, the sensor control system of the device can be configured as follows:

[0064] The application of a first RF pulse sequence to an MR sensor is controlled, and a corresponding first analysis method is used to analyze the first MR response signal from a mine ore bench or ore stockpile, wherein the first RF pulse sequence and the first corresponding analysis method have corresponding first predetermined sensitivity distribution curves.

[0065] One or more additional RF pulse sequences are applied to an MR sensor, and one or more corresponding additional analysis methods are used to analyze one or more additional MR response signals from a mine ore bench or ore stockpile, wherein the one or more additional RF pulse sequences and the one or more corresponding analysis methods each have corresponding additional predetermined sensitivity distribution curves.

[0066] The analysis of the first MR response signal and the other MR response signal is used to measure the corresponding first sensitivity distribution curve weight and the other sensitivity distribution curve weight.

[0067] The first sensitivity distribution curve is weighted and summed with the other sensitivity distribution curves to create a preferred spatial sensitivity distribution curve weighting; and

[0068] The preferred sensitivity distribution curve is used to weight the mineral concentrations that vary with depth in mine ore steps or ore stockpiles.

[0069] Generally, it should be recognized that a sensor control system may include multiple control or processing modules for controlling one or more components or functions of the device, and may also include one or more storage devices for storing data (such as predetermined sensitivity distribution curves, weighted sensitivity distribution curves, impedance values, etc.). The modules and storage devices may be implemented using one or more processing devices and one or more data storage units, and these modules and / or storage devices may be located in one location or distributed across multiple locations and interconnected by one or more communication links.

[0070] Additionally, modules may be implemented by computer programs or program code including program instructions. Computer program instructions may include source code, object code, machine code, or any other stored data operable to cause a processor to perform the described steps. Computer programs may be written in any form of programming language (including compiled or interpreted languages) and may be deployed in any form, including as standalone programs or as modules, components, subroutines, or other units suitable for a computing environment. Data storage devices may include non-transitory computer-readable storage media including instructions that cause a processor to perform the steps as described herein. Data storage devices may include suitable computer-readable media, such as volatile (e.g., RAM) and / or non-volatile (e.g., ROM, disk) memories.

[0071] Throughout this specification, the word “comprise” or its variations, such as “comprises” or “comprising”, shall be understood to mean that it includes the stated element, integer or step, or group of elements, integers or steps, but does not exclude any other element, integer or step, or group of elements, integers or steps. Brief description of the attached diagram

[0073] By way of example only, the implementation scheme will now be described with reference to the accompanying drawings, in which:

[0074] Figure 1 A component block diagram of an apparatus for measuring ore in a mine ore bench or ore yard according to an embodiment of the present disclosure is shown.

[0075] Figure 2 A schematic side view of an apparatus for measuring ore in a mine ore bench or ore yard according to an embodiment of the present disclosure is shown.

[0076] Figure 3a A cross-sectional view of a magnetic resonance sensor according to an embodiment of the present disclosure is shown;

[0077] Figure 3b It shows Figure 3a A plan view of the magnetic resonance sensor;

[0078] Figure 3c A cross-sectional view of a magnetic resonance sensor according to an embodiment of the present disclosure is shown;

[0079] Figure 4 A schematic diagram of a magnetic resonance sensor and a sensor control system according to an embodiment of the present disclosure is shown;

[0080] Figure 5c It shows a circular cross-section ( Figure 5a ) and non-circular cross sections ( Figure 5b Normalized coaxial field per unit current in the main loop of the main loop;

[0081] Figure 6 A schematic diagram of a magnetic resonance sensor and a sensor control system according to an embodiment of the present disclosure is shown;

[0082] Figure 7 The illustration shows the functionality of the loop forming the RF gradiometer according to an embodiment of the present disclosure;

[0083] Figure 8a The cross-section of the main loop without inserts in the plane of the main loop is shown, and Figure 8b The corresponding calculated normalized RF magnetic field profile is shown;

[0084] Figure 9a The cross-section of the main loop with the insert is shown in the plane of the main loop, and Figure 9b The corresponding calculated normalized RF magnetic field profile is shown;

[0085] Figure 10 It shows Figure 8a The main loop without inserts (blue traces) and Figure 9a The normalized coaxial field per unit current of the main loop (black trace) with the insert and the field generated by the eddy currents on the surface of the insert (red trace).

[0086] Figure 11An MR sensor is shown suspended above a half-space, wherein a sample including a thin disk can be positioned at different displacements (z) from the sensor in a plane parallel to the sensor surface.

[0087] Figure 12a -c shows three different sensitivity distribution curves obtained for three different pulse sequences and analysis methods; and

[0088] Figure 13a -b shows the mask used to extract signal power at different times in the FID waveforms corresponding to (a) early analysis and (b) late analysis. Detailed Implementation

[0089] One or more embodiments of this disclosure provide at least in part an apparatus suitable for measuring ore in mine benches or ore stockpiles using magnetic resonance (MR) technology. In some embodiments, the apparatus may utilize a through-hole (bulk ore measurement) MR method, which, in the case of mine benches, can be performed prior to blast hole drilling.

[0090] The advantages associated with pre-drilling penetration measurements may include:

[0091] a. Measurements do not need to be compatible with drilling bench conditions where the drill bit must be navigated in other ways.

[0092] b. High lateral (“xy”) measurement resolution is achievable. In this way, for example, based on the measurement results, precise scales can be used to guide single-bucket excavators and trucks for selective mining. Small areas of high-grade and low-grade ore depicted by the measurement data can be loaded onto trucks, allowing for higher precision truck guidance compared to existing methods that use data averaged over a much larger volume to allocate trucks for waste disposal or treatment.

[0093] c. Drilling operations can utilize available data prior to rig deployment, which can help optimize blasting characteristics.

[0094] d. The measurement process can be separated from existing mine bench activities. For example, benches can be used for measurements over extended periods.

[0095] e. Unlike point samples, which can be obtained using conventional drill cuttings sampling, most of the steps can be measured by equipment.

[0096] Magnetic resonance is radio frequency (RF) spectroscopy used in fields such as fundamental research on atomic and molecular bonding, as well as routine laboratory characterization for materials and medical imaging. Most applications involve routine nuclear magnetic resonance (NMR) laboratory use to measure hydrogen and carbon nuclei to analyze organic compounds. Earth-field NMR has also been used to infer the presence of water at depths using extremely large coils placed at very low frequencies on the ground, but not in mining environments.

[0097] Other less common categories of magnetic resonance include nuclear quadrupole resonance (NQR) and NMR in magnetically ordered materials. These less common categories are only applicable to the solid state but offer several important measurement advantages. First, in these cases, no external static magnetic field is required to define and measure the resonance. Second, the resonance frequencies are strongly dependent on chemical bonds and crystal structure, and are therefore typically highly specific to a particular crystalline phase.

[0098] For the purposes of this specification, “magnetic resonance” refers to these subclasses of NMR, NQR, or other related magnetic resonance spectroscopy that do not require the application of an externally applied static magnetic field.

[0099] In most types of MR, an RF magnetic field (typically the near-field region of an inductive coil or coil array) is applied to the material being analyzed. In practice, the near-field region can be defined as both the area inside the inductive sensor and the area around the sensor extending a distance equal to several diameters of the sensor.

[0100] A measurement sequence applicable to a pulsed MR method in a device according to this disclosure involves an excitation phase followed by a detection phase. In the excitation phase, a pulsed RF current is driven in a sensor to irradiate the material located in the near-field region with an RF field. The RF current is driven by a radio frequency transmitter coupled to the sensor. Irradiation results in the generation of dynamic nuclear magnetization of the target nuclei in the material, which generates an associated RF response field. The response field can retain a significant amplitude after the RF excitation current is cut off.

[0101] If an RF response field is generated in the near-field region of a sensor coil (the same or different induction coils used for excitation), a voltage can be generated at the sensor's output terminal. This sensor can then be used to detect the RF response field by detecting the signal (and noise) voltage at the sensor's output terminal using an RF receiver. This corresponds to the detection phase of a measurement sequence. Therefore, both the transmitter and receiver are coupled to the sensor, but typically at different times during the measurement process. An RF switch can be used to control the coupling of either the transmitter or receiver to the sensor. For detection based on Faraday's law, the terminal voltage is proportional to the rate of change of magnetic flux through the aperture defined by the sensor coil over time. The amplitude of the signal voltage generated in the sensor coil can be used to determine the mass of a specific material within the sensing volume. This can be determined by applying a simple linear coefficient between the measured signal and the mass within the sensing volume. The concentration and grade of the material can also be determined using the auxiliary knowledge of the mass load within the sensing volume.

[0102] For example, the mineral content M can be calculated using the following formula:

[0103]

[0104] Where a is the calibration factor and S is the magnetic resonance signal voltage.

[0105] Grade G can be calculated using the following formula:

[0106]

[0107] Where b is a fixed calibration factor, and M o It is an estimate of the mass of the ore in the sensing area. M can be... o It is assumed to be a fixed value, or a value determined by measuring the density of ore in the mine's ore bench or ore yard.

[0108] Known applications of MR technology typically involve measuring relatively small samples (e.g., less than 1 L in sample volume) and performing them in controlled environments, such as fully electromagnetically shielded sensors, or in similarly fully shielded magnetic resonance imaging (MRI) facilities. In this regard, electromagnetic (EM) shielding is required to avoid poor signal-to-noise ratios caused by external electromagnetic disturbances interfering with the detection of MR signals.

[0109] Figure 1 The illustration shows an apparatus 100 for measuring ore in a mine ore bench or ore stockpile 201 according to an embodiment of the present disclosure. The apparatus 100 includes a mobile platform 200, at least one magnetic resonance (MR) sensor 300 (included in the mobile platform 200), a MR sensor control system 400, and optionally a platform control system 500. Reference Figure 2The platform defines platform area 202. Platform 200 is, for example, a mechanical structure with a frame, which can accommodate the mechanical integration of at least one magnetic resonance sensor 300 and is movable above the mine ore bench or ore stockpile 201, such as... Figure 2 As shown in the diagram.

[0110] Sensor control system 400 is typically configured to control the features of a device to aid in the ability of a magnetic resonance sensor to operate in a mobile platform environment and / or to provide more reliable or accurate measurements using the magnetic resonance sensor 300. Sensor control system 400 can control, for example, at least one of the following: the positioning of at least one MR sensor 300 relative to a region of platform 200 and / or relative to a mine ore bench or ore stockpile; the positioning of elements included in the MR sensor 300 relative to each other; the electromagnetic suppression characteristics of at least one magnetic resonance sensor 300; and / or the sensitivity of at least one magnetic resonance sensor 300 as the sensor 300 varies with distance from the mine ore bench or ore stockpile.

[0111] The platform control system 500 can control at least one of the following: movement of the mobile platform 200 (e.g., stopping and starting movement, and / or direction of travel); and information exchange between the equipment 100 and one or more other components of the mine environment. In practice, the sensor control system 400 and the platform control system 500 can be integrated into the equipment's broader control system or remain as separate control system elements.

[0112] The mobile platform 200 has physical dimensions defining the volume or area of ​​the platform area 202. In some embodiments, the mobile platform 200 may be adapted to allow measurement of ore grade at different locations on ore mine steps or ore stockpiles 201.

[0113] In some embodiments, the mobile platform 200 includes a chassis with wheels or sliders. The mobile platform 200 may be towed by a vehicle or be self-propelled. For example, the mobile platform 200 may be self-motorized. In some embodiments, the mobile platform 200 may be an autonomous system programmed to mark predefined areas on a mine ore step. In some embodiments, a sensor control system 400 or components thereof may be integrated into the mobile platform. Alternatively or additionally, the sensor control system or components thereof may be located in a separate structure that moves with the mobile platform (e.g., a tractor). In some embodiments, the separate structure is tethered to establish a communication link between the sensor control system 400 and the mobile platform 200. In some embodiments, the sensor control system 400 may be fixed in a location in a separate structure at a convenient point on the mine ore step and tethered to the mobile platform.

[0114] To perform representative measurements of ore material, it may be necessary to measure potentially large volumes of ore (e.g., many cubic meters). Magnetic resonance (MR) frequencies associated with the selected / target mineral phase are typically below 100 MHz. At such frequencies, the electromagnetic induction skin depth of rock types (such as granite) is typically at least several meters. Therefore, the magnetic resonance technique according to this disclosure can provide bulk measurements of ore in mine ore benches or ore stockpiles.

[0115] For large-volume bulk measurements, ore steps or ore stockpiles in ore mines can be approximated as ore half-spaces.

[0116] To optimize the detection of ores that are located at a large distance from sensors, aspects of the device, including at least one MR sensor of device 100, can be potentially combined and optimized.

[0117] For example, device 100 can be configured to maximize the radio frequency (RF) field at a greater distance from MR sensor 300 using available RF power. Below a certain field strength threshold, the sensed response field decreases exponentially. The increased RF field strength at depth enables an increase in the sensed volume of a mine ore step or ore stockpile.

[0118] In addition, the MR sensor 300 can be configured to take into account changes in electrical impedance associated with proximity to ore and other machinery.

[0119] Additionally, the MR sensor 300 can be configured to reject potentially high levels of external electromagnetic interference. For measuring ore in mine ore steps or ore yards using a platform structure, completely shielding the mine ore steps or ore yards during measurement is impractical. At most, partial shielding can be applied. Measuring ore in mine ore steps or ore yards using a platform arrangement can be considered an "open system," where complete electromagnetic (EM) shielding technology / equipment may not be applicable, and therefore other devices to reject electromagnetic interference may be particularly advantageous.

[0120] Also advantageously, the MR sensor 300 is configured to return uniformly weighted measurements of mine ore or ore stockpiles in platform area 202. That is, in some embodiments, it is preferred that the MR sensor 300 is not overly sensitive to non-uniform mineral or elemental grade distributions. For example, this can be applied to situations where high-grade ore material very close to the sensor leads to an overestimation of the total grade, due to the fact that sensor sensitivity is stronger in the spatial region closer to the MR sensor 300.

[0121] As discussed in more detail in Example 4 below, different configurations of the pulse sequence applied to the MR sensor 300 can modify the spatial sensitivity characteristics of the MR sensor 300 in the measurement region 205 (or ore half-space). In embodiments of this disclosure, the pulse sequence and signal analysis method can be modified to preferentially suppress the sensitivity of the MR sensor 300 in areas very close to (e.g., adjacent to) the MR sensor 300, while leaving the sensitivity far from the MR sensor 300 relatively unaffected.

[0122] For one or more RF pulse sequences applied to the MR sensor 300 and one or more associated analytical methods (masks), one or more predetermined sensitivity distribution curves can be determined for the MR sensor 300. Masks can be applied to the time-domain MR signal to prioritize the response at different depths of a mine bench or ore stockpile for diagnostic purposes. For a specific mine ore or ore stockpile to be analyzed, weights can be applied to each measurement in the sensitivity distribution curves. Weights of one or more sensitivity distribution curves can be used to estimate the depth-dependent mineral concentration in the mine bench or ore stockpile.

[0123] In one embodiment, the sensor control system 400 of device 100 is configured as follows:

[0124] At least one RF pulse sequence is controlled to be applied to an MR sensor 300, and at least one correspondence analysis method is used to analyze the MR response signal from a mine ore step or ore stockpile, wherein the at least one RF pulse sequence and the at least one correspondence analysis method each have a corresponding predetermined sensitivity distribution curve.

[0125] The analysis of the MR response signal is used to measure the weighted corresponding sensitivity distribution curve; and

[0126] Sensitivity distribution curves are used to weight the mineral concentrations that vary with depth in mine ore benches or ore stockpiles.

[0127] In some embodiments, for example, according to the method described in more detail in embodiment 4, the equipment or associated method for measuring ore (including, for example, measuring mineral concentration or grade) may utilize or include:

[0128] i. For the first RF pulse sequence applied to the MR sensor 300 and the first associated analysis method (mask), determine a first predetermined sensitivity distribution curve for the MR sensor 300;

[0129] ii. For one or more additional RF pulse sequences applied to the MR sensor 300 and one or more associated analysis methods (masks), determine one or more additional predetermined sensitivity distribution curves for the MR sensor 300;

[0130] iii. The first RF pulse sequence is provided to the MR sensor 300 and the obtained MR response signal from the mine ore bench or ore stockpile is analyzed using a first associated analysis method to measure the first sensitivity distribution curve weighted.

[0131] iv. Provide one or more additional RF pulse sequences to the MR sensor 300 and use one or more additional associated analytical methods to analyze one or more resulting MR response signals from the mine ore step or ore stockpile to measure one or more additional sensitivity distribution curves weighted by one or more additional sensitivity distribution curves.

[0132] v. Weight the sensitivity distribution curves measured in steps (iii) and (iv) to create a preferred spatially weighted sensitivity distribution curve; and

[0133] vi. Use the preferred spatial sensitivity distribution curve obtained in step (v) to estimate the depth-dependent mineral concentration in the mine ore bench or ore stockpile.

[0134] For example, in one embodiment, the sensor control system 400 of device 100 is configured as follows:

[0135] The first RF pulse sequence is controlled to be applied to the MR sensor 300, and the first MR response signal from the mine ore bench or ore stockpile is analyzed using a corresponding first analysis method, wherein the first RF pulse sequence and the first corresponding analysis method have corresponding first predetermined sensitivity distribution curves.

[0136] One or more additional RF pulse sequences are controlled to be applied to the MR sensor 300, and one or more corresponding additional analysis methods are used to analyze one or more additional MR response signals from a mine ore step or ore stockpile, wherein the one or more additional RF pulse sequences and the one or more corresponding analysis methods each have corresponding additional predetermined sensitivity distribution curves.

[0137] The analysis of the first MR response signal and the other MR response signal is used to measure the corresponding first sensitivity distribution curve weight and the other sensitivity distribution curve weight.

[0138] The first sensitivity distribution curve is weighted and summed with the other sensitivity distribution curves to create a preferred spatial sensitivity distribution curve weighting; and

[0139] The preferred sensitivity distribution curve is used to weight the mineral concentrations that vary with depth in mine ore steps or ore stockpiles.

[0140] Now for reference Figure 3a and Figure 3b At least one MR sensor 300 according to embodiments of the present disclosure is described in more detail. For example... Figure 3a As shown, the magnetic resonance sensor 300 includes a main loop 301 and an auxiliary loop (drive loop 302). The main loop 301 can be positioned above or resting on top of a mine ore step or ore stockpile 201. The auxiliary loop 302 is coaxially positioned with the main loop 301 and positioned above the plane of the main loop 301. The drive loop 302 is electrically isolated from and magnetically coupled to the main loop 301, and resonates in series at an appropriate frequency. The main loop 301 resonates at a series resonant frequency that is substantially the same as (typically within 2%) the resonant frequency of the drive loop.

[0141] Drive loop 301 is fed by a radio frequency (RF) transmitter at drive loop feed terminal 3013. The RF drive current in drive loop 302 excites the RF drive current in main loop 301, thereby generating an RF magnetic field in measurement area 205 of device 100, which is suitable for altering the magnetization of a target nucleus in a mine deposit step or ore stockpile 201. Typically, measurement area 205 will be at least partially contained within platform area 202 of a moving platform. The precession of the magnetization of the target nucleus excites an RF response current in main loop 301, and the RF response current in main loop 301 induces a corresponding RF response current in drive loop 302, which is monitored by an RF receiver (not shown) coupled to drive loop 302.

[0142] At least one magnetic resonance sensor 300 has a main loop 301 adapted to have a series resonant frequency, and at least one magnetic resonance sensor adapted to have an associated operating frequency suitable for magnetic resonance measurement of the target nucleus. Those skilled in the art will understand that the resonant absorption and emission of energy by the entire target nucleus can have a frequency distribution. The peak magnetic resonance frequency is defined as the pattern of the frequency distribution. When the series resonant frequency is close to the peak magnetic resonance frequency, the operating frequency of at least one magnetic resonance sensor 300 can be suitable for magnetic resonance measurement of the target nucleus.

[0143] By enabling a larger RF signal current to be excited in the main loop 301, setting the operating frequency to be close to the peak resonant frequency of the target nucleus improves the sensitivity of the magnetic resonance sensor 300 to a small number of target nuclei. For example, the operating frequency can be set such that the frequency of the excited RF current is within two standard deviations from the peak magnetic resonance frequency of the target nucleus (of the magnetic resonance frequency distribution of the target nucleus).

[0144] Pay special attention to the main ring road 301 and refer to it. Figure 3a and Figure 3bThe main loop 301 is a planar loop (e.g., a single-turn coil) positioned above or resting on top of the mine ore bench or ore stockpile 201. The main loop 301 conducts RF current, making it primarily in phase above the main loop. The RF current generates an RF magnetic field suitable for altering the magnetization of the target nucleus; such as by resonantly exciting the target nucleus to change the orientation of the net magnetization of the entire target nucleus. Furthermore, the main loop 301 is adapted to have an RF signal current excited by the precession of the magnetization of the target nucleus in the analyzed ore material.

[0145] The main loop 301 is divided into discrete conductive segments 3011a-d separated by tuning capacitors 3012a-d. The capacitances of the tuning capacitors 3012a-d are approximately equal (e.g., within 10% of each other) and are chosen to resonate in series with the main loop 301. The segmentation into segments 3011a-d is to achieve a substantially uniform RF current in the main loop 301. Uniform RF current optimizes near-field uniformity in the illuminated half-space of a mine ore step or ore stockpile. This segmentation also minimizes the maximum voltage at points on the main loop 301 due to the non-uniform charge distribution in the near-field region (i.e., the near zone) of the electromagnetic field (EM) relative to the main loop 301. This reduces the RF loss mechanisms associated with the non-uniform loop charge distribution, thereby reducing the main loop resistance and allowing for an increase in the RF field amplitude in the near-field region.

[0146] In some implementations, at least one of the tuning capacitors 3011a-d is adjustable to allow modification of the series resonance of the main loop 301.

[0147] Advantageously, the inductance of the main loop 301 is minimized without compromising field generation in the measurement region 205. The quality factor of the loop is defined as the loop reactance divided by the loop resistance. For a fixed quality factor of the loop, the minimum inductance implies the corresponding minimum value of the loop resistance. Typically, the main loop 301 can be considered as extending along a loop path.

[0148] In some embodiments, the cross-section of the main loop 301 (in a plane perpendicular to the loop path) may be circular, thereby providing the main loop 301 with a substantially annular overall shape. However, it has been advantageously recognized in this disclosure that different shapes (non-circular) of the cross-section of the main loop may also be utilized, for example, to minimize the inductance of the main loop 301.

[0149] Compared to the circular cross-section of a toroidal coil, the shaping of the main loop cross-section can reduce inductance. Figure 5cA comparison of the field per unit current generated by main loops with different cross-sectional shapes is shown, with the constraint that the shapes have the same vertical dimension (by maintaining the same vertical dimension, differences in the field per unit current can be identified solely based on the shape variation, rather than due to modifications in the distance between the main loop and the ore). Figure 5c The document provides two traces, one of which originates from the circular cross-section / ring main loop (…). Figure 5a The normalized coaxial field obtained is used for the other trace, which is obtained using a non-circular main loop. Figure 5b The normalized coaxial field obtained is shown below. For each case, the field generated by the main loop is practically the same. However, there are significant differences in loop inductance for each case, as seen in Table 1 below. Although the non-circular cross-sectional shape has the same vertical dimensions and coaxial normalized field distribution as the conventional circular shape, the non-circular cross-sectional shape has 20% lower inductance. Therefore, the non-circular cross-sectional shape is advantageous for reducing sensor inductance and resistance.

[0150] Table 1 - Figure 5a and Figure 5b The loop inductance with the shown loop cross-sectional geometry

[0151]

[0152] like Figure 5b As seen, the non-circular shape is one with a convex boundary 3015a and an opposing concave boundary 3015b. The convex boundary 3015a is located radially outward of the main loop, and the concave boundary 3015b is located radially inward of the main loop. The non-circular shape can be considered as a kidney shape, a crescent shape, or a crescent shape formed by two intersecting ellipses. Other non-circular shapes are possible.

[0153] Turning to drive loop 302, which uses multiple capacitors 3022a-d in series resonantly at the operating frequency and is magnetically coupled to main loop 301. The mutual coupling between drive loop 302 and main loop 301 can be adjusted by changing the position of drive loop 302 relative to main loop 301. This variable position allows modification of the real portion of the input impedance at feed terminal 3013. This can be considered in light of the variable impedance imparted by the variable ore content in the mine ore steps or ore stockpile 201.

[0154] refer to Figure 4 The device may include at least one impedance monitor 307 and an RF receiver 308. The impedance monitor 307 monitors the reactive and / or resistive impedance at the feed terminal of the drive loop 302 and provides details of the monitored impedance to the sensor control system 400. The RF receiver 308 detects signal (and noise) voltages during the detection phase of the measurement sequence.

[0155] In some implementations, the sensor control system 400 is configured to adjust the capacitance of at least one capacitor in the main loop 301, for example, based on the monitored reactive impedance. This can be implemented such that the reactive impedance at the feed terminal of the drive loop 302 is adjusted to a target reactive impedance. The target feed terminal reactive impedance is typically close to zero ohms.

[0156] In some implementation schemes, such as Figure 4 As shown, the sensor control system 400 includes a displacement monitor 309 to monitor the position, orientation, and / or displacement between at least one MR sensor 300 and the mine ore step or ore stockpile 201. In these embodiments, the sensor control system 400 adjusts the position and / or orientation based on the monitored displacement. The sensor control system 400 can adjust the position and / or orientation based on the monitored displacement to maintain a fixed interval between the mine ore step or ore stockpile 201 and the main loop 301 of the MR sensor 300.

[0157] In some embodiments, the sensor control system 400 is configured to control the position and / or orientation of at least one MR sensor 300 relative to a mine ore step or ore stockpile 201. Alternatively or additionally, the sensor control system 400 may be configured to control the position and / or orientation of a drive loop 302 relative to a main loop 301. In some embodiments, the sensor control system adjusts the position and / or orientation based on monitored resistive impedance. In some embodiments, the sensor control system 400 adjusts the position and / or orientation of the MR sensor 300 relative to the mine ore step or ore stockpile 201 such that the resistive impedance at the feed terminal of the drive loop 302 is within a predetermined resistive impedance range. This resistive impedance range is typically within 30% of the target feed terminal resistive impedance. Subsequently, the sensor control system 400 may adjust the position and / or orientation of the drive loop relative to the main loop such that the resistive impedance at the feed terminal of the drive loop is at a target resistive impedance. The target resistive impedance is a fixed system impedance that is predetermined and selected to optimize RF power delivery from the transmitter to the sensor. The typical target resistive impedance is 50 ohms.

[0158] Maintaining a fixed and optimized impedance at the (high-power) drive loop feed terminal 3013 is advantageous. The position of the drive loop 302 can be set based on the measurement of the difference between the input impedance of the drive loop feed terminal and the target input impedance. The position of the drive loop 302 can be changed based on vertical or angular displacement.

[0159] Those skilled in the art will understand that at least one MR sensor 300 may include other conductive elements, impedance monitors, actuators, combination loops, inserts, reflectors, drive coils, and / or other reflectors / shrouds.

[0160] refer to Figure 3a In some embodiments, at least one magnetic resonance sensor 300 further includes a passive reflector 303, which is coaxial with the main loop 301 and positioned above the main loop 301 and the drive loop 302. In a preferred embodiment, the reflector 303 is configured (e.g., positioned) to reduce radiation and magnetic near-field in the direction opposite to that of the measurement area 205 (i.e., opposite to the ore half-space). In some embodiments, the reflector is configured to reduce radiation in the upward direction from the mine ore step or ore stockpile 201. In some embodiments, such as Figure 3a As illustrated, reflector 303 can be a substantially flat disk-shaped structure without an aperture. In alternative embodiments, such as Figure 3c As shown in the figure, the reflector 303' can be a dome-shaped structure without an aperture. In the case of the dome-shaped reflector 303' structure, the concave surface of the dome faces the main loop 301.

[0161] Still referencing Figure 3a In some embodiments, at least one magnetic resonance sensor 300 may include a passive loop 304 (single-turn coil) coaxially positioned with the main loop 301, and as shown in the figure. Figure 3a The passive loop 304 is positioned above or within the plane of the main loop 301. It is magnetically coupled to the main loop 301. The passive loop 304 has a specially selected lumped impedance of capacitors inserted in series to provide suppression of external electromagnetic interference (EMI) in the main loop 301. In some embodiments, for example, the lumped impedance of a specific capacitor is varied by a sensor control system 400 to optimize EMI suppression / minimize the RF noise voltage based on a measurement of the RF noise voltage at the drive loop feed terminal. At least one MR sensor 300 may include a noise monitor to monitor the RF noise voltage at the feed terminal of the drive loop 302. An RF receiver may act as the noise monitor.

[0162] In some implementations, reflector 303 is located between main loop 301 and passive loop 304. In this respect, reflector 303 can play a role in reducing the mutual coupling between main loop and passive loop 304, as discussed in more detail in Example 2 below.

[0163] In some implementation schemes and in Figure 3aAs illustrated in the implementation, at least one MR sensor 300 includes a resistor loop 305 magnetically coupled to a main loop 301 and terminated with a resistor. The orientation of the resistor loop 305 can be modified relative to the main loop 301 to impart a change in the resistive impedance of the drive loop feed network. The resistor loop 305 can be used to modify the total resistive loss in the magnetic resonance sensor 300 in order to control the RF current in the main loop 301.

[0164] In some embodiments, the sensor control system 400 is configured to adjust the orientation of the resistance loop 305 relative to the main loop 301. In these embodiments, the device 100 may include an impedance monitor to monitor the resistive impedance at the feed terminal of the drive loop 302, and the sensor control system 400 may be configured to adjust the orientation of the resistance loop 305 relative to the main loop 301 based on the monitored resistive impedance. In this way, the resistive impedance at the feed terminal of the drive loop 302 can be positioned at or maintained at a target resistive impedance.

[0165] Still referencing Figure 3a In some embodiments, at least one magnetic resonance sensor 300 includes a passive insert 306 positioned in the plane of the main loop 301 and within the minimum radius of the main loop 301. The passive insert 306 may be a disk or elliptical structure without an aperture. In some embodiments, the passive insert 306 is an oblate spheroid. The outer surface of the insert may be made of a highly conductive material (such as copper). The internal portion of the insert may be made of the same material as the outer surface or in a different manner.

[0166] According to this disclosure, the passive insert 306 can be used to suppress the RF field immediately adjacent to the main loop 301, but is configured to minimize its impact on the RF field at a greater distance from the main loop 301. Therefore, the passive insert 306 can be used to suppress eddy currents in the measurement region 205 (i.e., the ore half-space) immediately adjacent to the main loop 301, thereby reducing the effective resistance of the main loop. This configuration thereby increases the current in the main loop 301 and provides an overall increase in the RF field at locations away from the main loop 301.

[0167] Another advantage of the passive insert 306 is that it can flatten the MR sensitivity distribution curve in the measurement region 205 (i.e., the ore half-space) by reducing the local sensitivity at a location very close to the sensor.

[0168] refer to Figure 6The control system 400 may include actuators (600a-d) to modify the position and / or orientation of the magnetic resonance sensor 300 and its components (including the main loop 301, drive loop 302, passive loop 304, and resistor loop 305). For this purpose, the sensor control system may use measured information, including the complex impedance of the sensor drive loop feed terminal, the noise voltage at the sensor drive loop feed terminal (e.g., as measured by a radio frequency receiver), and the distance between the sensor front and the surface of a mine ore step or ore stockpile (e.g., by means of ultrasonic or laser distance measurement methods).

[0169] Example 1 - Passive Loop ("Gradient") Function

[0170] refer to Figure 7 When two loops (“Loop 1” and “Loop 2”) are immersed in a uniform interfering magnetic field, the structure of the scattered field can be used to provide a certain level of RF interference suppression in one of the loops. The analysis can begin by assuming that the external interfering field contributes electromotive forces ε1 and ε2 to Loop 1 and Loop 2, respectively. The electromotive forces will be proportional to the respective loop regions. In this analysis, for example, according to the aforementioned embodiment, Loop 1 can be identified as the “main loop” and Loop 2 can be identified as the “passive loop”. For example, a bowl-shaped or disc-shaped “passive reflector” according to the aforementioned embodiment, and which will be discussed further, can be inserted between Loop 1 and Loop 2, but is omitted from the analysis for now. It is further assumed that ε1 and ε2 are in phase. This generally means that the loops are separated by a distance much smaller than the free-space wavelength and coupled to the same field polarization. Therefore, the ratio α = ε2 / ε1 is a positive real number. It is also assumed that the loops are physically smaller than the free-space wavelength. Therefore, the principle of lumped circuit analysis can be used to analyze the electromotive force generated in each loop due to the external field and the scattered field from another loop.

[0171] When each loop is completely isolated from another loop (mutual inductance M = 0), each loop has the following properties: and The loop path is typically surrounded by a complex series of loop impedances. These impedances encapsulate internal loop resistances and inductances as well as external inductances. They also include any terminating impedances of the loop, loaded in the form of tuning elements, and, in the case of loop 1, the input impedance of the receiver present during the receiving phase of the measurement. When M ≠ 0, the total electromotive force ε in loop 1 can be represented. T for

[0172]

[0173] in We seek to make Minimize the parameter combination. Next, it should be noted that the amplitude of the molecule in (1) can be minimized by wisely choosing M and the loop 2 terminator:

[0174]

[0175] in The approximation for small and It is effective. This specific choice results in:

[0176]

[0177] It has been observed that by taking small measures , can obtain |ε T |The potential decrease is relatively large. It must be verified that D is also not small. D can be rewritten as follows:

[0178]

[0179] To make further progress, we note that in order to achieve efficient RF power coupling during the excitation phase of the measurement, loop 1 typically operates in a manner very close to resonance, where Z1 is essentially a purely real number (X1 = 0). Under this assumption, |D| is always > 1.

[0180] As an example, the following parameters can be chosen (independently): α = 2, r2 / r1 = 2, = 0.1. Then β ~ -0.5 and |D| = 5.1. With these parameters, a positive phasing of the scattered field is achieved, and the RFI reduction factor according to equation (3) is 0.019 or 34 dB.

[0181] Finally, we can examine the impedance Z "seen" by the test voltage applied in series with loop 1. T (where equation (2) also applies), which takes into account the reflection impedance of loop 2, since this is the relevant impedance related to the current drive in loop 1:

[0182]

[0183] in This is the impedance when loop 1 is completely isolated, but the receiver circuitry does not contribute to the loop load. In fact, Typically similar to Z1. It should be noted that, under the selected parameters, the resistance (Z...) TThe real part of the loop (β) contributes only a small amount due to the proximity of loop 2 (since |β| < 1). This ensures efficient power coupling from the external drive circuitry to loop 1. The reactance of loop 1 is also only slightly affected. Therefore, for magnetic resonance measurements, loop 1 can excite a significant RF magnetic field in a region defined by a field mode similar to that produced by a single, completely isolated loop. By applying the reciprocity principle, the same loop can thus receive signals generated in the same region. However, due to the phase and amplitude of the scattered field arrangement, RF interference (RFI) magnetic fields with equal phase and amplitude across the two loops are significantly suppressed. Numerical analysis of loop arrangements including free-space radiation effects yields similar RFI suppression properties.

[0184] Therefore, providing a passive loop (e.g., as described in the foregoing embodiments) can provide suppression of external electromagnetic interference in the main loop.

[0185] Example 2 - The function of passive reflectors

[0186] One function of the passive reflector is to reduce the RFI field of impact loop 1 (the main loop). This function is achieved in the absence of loop 2. Placing loop 1 in the reduced field region reduces ε1 and provides some RFI suppression.

[0187] Another function of the passive reflector is to reduce the mutual coupling between the main loop and the passive loop. The above analysis does not acknowledge any practical limitations in the selection of parameters for achieving RFI suppression. For example, in the above analysis, we can assume r2 = 10mΩ. From the selected parameter values, we get jX2 = -100jmΩ and jωM = 50jmΩ. If the mass factor of the isolation loop 2 is 500, the reactance of the untuned loop is 5jΩ. Therefore, the required mutual inductance is extremely small compared to the reactance of the untuned loop. Achieving such relatively small coupling between two loops of similar size would typically involve impractical large spatial spacing, which is incompatible with compactness requirements. A passive reflector is inserted between loop 1 and loop 2. This is not a resonant structure and does not significantly modify the phase of the scattered near-field. Instead, it partially shields the field generated by one loop by supporting eddy currents on the reflector surface. This optimizes the value of M between loop 1 and loop 2 and allows for the development of a compact spatial arrangement of the loops.

[0188] Another function of the passive reflector is to increase the ratio α = ε2 / ε1 (and thus reduce β). This reduction in β is advantageous from the perspective of further reducing the reflection impedance that appears in loop 1 due to the proximity of loop 2 (as shown in Equation 5). This provides a more efficient magnetic resonance signal coupled to loop 1.

[0189] Example 3 - Passive Insert Function

[0190] For example, the insert according to the passive insert 306 described with respect to the above embodiment can be used for a variety of purposes. For example, the insert reduces the RF field strength immediately adjacent to the main loop. This has the effect of reducing eddy currents in the ore very close to the loop, and therefore also reducing the reflection resistance in the main loop. This produces the advantage that a significantly increased current can be driven in the main loop at the same available power level. Figures 8 and 9 compare the use of the insert without ( Figure 8a and Figure 8b ) and with inserts ( Figure 9a and Figure 9b The electric field strength per unit current is calculated using contour maps of the main loop. Figure 9b In this context, the insert is a flattened sphere placed in the plane of the main loop (see...). Figure 9a (The main loop section shown). Figure 9b The profile very close to the loop indicates a significantly lower field strength. On the other hand, the field strength at distances from the loop is much less affected by the insert. Depending on the severity of eddy current losses, the increase in current resulting from the reduction in the main loop resistance leads to an overall sensitivity advantage at greater distances from the sensor.

[0191] The insert also reduces the sensitivity of the main loop at distances very close to the sensor, compared to distances further away, thus “flattening” the sensor response relative to depth. This is an advantage for providing greater sensing uniformity across the ore half-space. Figure 10 A comparison graph is shown between the normalized field (coaxial) caused by the main loop only (blue trace) and the loop plus insert (black trace). The red trace is the field generated by eddy currents on the insert surface, which are used to cancel the field very close to the main loop. The RF field very close to the main loop is preferentially reduced compared to the field far from the main loop. Because sensitivity depends on the normalized RF field, an improvement in sensing uniformity is achieved.

[0192] Example 4 - Obtaining Uniform Spatial Sensitivity

[0193] Most sensing technologies are limited when applied to unilateral measurement applications by the fact that the sensed field or flux attenuates away from the sensor, and the measurement response decreases rapidly away from the sensor location in a similar manner, typically by at least "1 / r". 2 The electromagnetic field from the loop typically decays monotonically away from the loop aperture, but this can cause the MR response distribution curve to peak at a certain distance from the sensor. This is because the MR resonant response is nonlinear in the applied excitation field. Various MR phenomena exist that can be used to profile (including saturation, internal destructive disturbances, and variable magnetization rotation, etc.).

[0194] Experiments have been conducted to demonstrate the method used for sensitivity profiling. Figure 11 An MR sensor is shown suspended above a half-space, where a sample, including a thin disk, can be positioned at different displacements from the sensor in a plane parallel to the sensor surface. The disk is used to simulate a thin mineralization layer in the half-space below the sensor. The spacing between the disk and the sensor is varied to characterize the sensor's response relative to mineral depth for different MR pulse sequences and signal analysis methods (masks). Different relationships between sensitivity and sample depth are obtained for each type of sequence and signal analysis method. These relationships are referred to herein as "sensitivity distribution curves." The above experiments represent a calibration process in which various sensitivity distribution curves are generated before their use in ore half-space measurements.

[0195] Figure 12a -c shows three different sensitivity distribution curves obtained for three different pulse sequences and analysis methods (masking). Distribution curve A ( Figure 12a This is due to the analysis of the MR signal power during the early stage of free induction decay (FID) generated by a specific pulse sequence (in this case, a single long pulse). Distribution curve B ( Figure 12b This was caused by analysis of the same type of FID at a later time.

[0196] Figure 13a and Figure 13b A masking method for generating sensitivity distribution curves is illustrated. A mask has been applied to a specific time domain of the signal to extract specific portions of the signal power occurring during those time periods. In this example, the mask is used in the period corresponding to the earlier analysis ( Figure 13a ) and late-stage analysis ( Figure 13b The signal power is extracted at different times from the FID waveform of the image. The distribution curve C (as shown) Figure 12c The result (shown) is due to the analysis of magnetic resonance responses originating from shorter pulse lengths. In actual ore measurements, many different sensitivity profiles can be developed because MR measurement parameters can be dynamically varied in real time to interleave specific sensitivity profiles during normal operation.

[0197] It should be noted that a relatively constant sensitivity with depth can be achieved by simply using the pulses and analysis parameters corresponding to distribution curve A. This indicates that, for this configuration, MR measurements are not “overwhelmed” by the slope of the approach surface; that is, the measurements are not strongly biased according to the slope of the upper region.

[0198] Figure 12aThe sensitivity distribution curves in -c also allow for the development of composite sensitivity distribution curves of desired shapes through linear combinations of available sensitivity distribution curves. In general, the sensitivity distribution curves form a "base set"; each sensitivity distribution curve can be summed in a weighted linear combination to reproduce a new sensitivity distribution curve designed to strongly overlap with the specified measurement area.

[0199] The weighting process is performed as follows. Each MR measurement configuration provides a single waveform for the entire half-space below the sensor. A signal mask is used to analyze the waveform for each configuration to extract one or more sensitivity distribution curves “weighted”. For example, for a long-pulse configuration, the early and late signal power are analyzed to provide two figures (S0 and S1 respectively). A and S B These two figures estimate the weighted average of each sensitivity distribution curve pattern in the half-space. In the example discussed here, the intensity S of the third sensitivity distribution curve is... C This also originates from the second MR measurement configuration (short pulse configuration). Each sensitivity distribution curve weight is normalized to a known calibrated weight corresponding to a uniform ore grade of a given value. Therefore, the sensitivity distribution curve intensity carries information related to the distribution curve and the quantitative grade value.

[0200] Once the weights of the sensitivity distribution curves are determined, they can be used to weight the corresponding sensitivity distribution curves to estimate the shape of the grade distribution curve in a specified region of the half-space. Multiple sensitivity distribution curves can be used to optimize the flat response with depth, or alternatively, a combination of sensitivity distribution curves with preferential weighting in a specific region can be set. The latter approach allows for depth-based slope mapping.

[0201] Those skilled in the art will understand that many variations and / or modifications can be made to the above embodiments without departing from the broad general scope of this disclosure. Therefore, embodiments of the invention are to be considered illustrative rather than restrictive in all respects.

Claims

1. An apparatus for measuring ore in a mine bench or ore stockpile, the apparatus comprising: A mobile platform defining a platform area, wherein the mobile platform can be positioned on or above a mine ore bench or stockpile. At least one magnetic resonance (MR) sensor is included in the mobile platform, the MR sensor comprising: The main loop can be located within the platform area situated above or on the mine's ore bench or ore stockpile. A drive loop is located above the main loop and is electrically isolated from and magnetically coupled to the main loop, wherein an RF transmitter can be coupled to a feed terminal of the drive loop to drive an RF drive current in the drive loop, and an RF receiver can be coupled to the drive loop to monitor an RF response current in the drive loop. The device further includes: A magnetic resonance sensor control system configured to control at least one of the following: The positioning of at least one MR sensor relative to the platform area and / or mine ore steps or ore stockpile; The positioning of the components included in the MR sensor relative to each other; The electromagnetic suppression characteristics of the at least one MR sensor; and / or The sensitivity of the at least one MR sensor as the distance of the sensor from the mine ore step or ore stockpile varies.

2. The device of claim 1, wherein the main loop comprises a plurality of conductive segments and a capacitor positioned between the conductive segments.

3. The device of claim 2, wherein the capacitors are evenly spaced along the main loop and the capacitance of each capacitor is substantially equal.

4. The device of claim 2 or 3, wherein the capacitance of at least one capacitor in the main loop is adjustable.

5. The device of claim 4, wherein the sensor control system is configured to adjust the capacitance of at least one of the capacitors in the main loop.

6. The device of claim 5, further comprising an impedance monitor to monitor the reactive impedance at the feed terminal of the drive loop, wherein the sensor control system adjusts the capacitor based on the monitored reactive impedance.

7. The device of claim 6, wherein the sensor control system is configured to adjust the capacitor such that the reactive impedance at the feed terminal of the drive loop is at a target reactive impedance.

8. The device of claim 2 or 3, wherein the conductive segment and capacitor of the main loop extend along the annular path, and in cross-section, in a plane perpendicular to the annular path, the conductive segment has a non-circular cross-sectional shape.

9. The device of claim 8, wherein the non-circular cross-sectional shape is a shape having a convex boundary and an opposing concave boundary.

10. The device of claim 9, wherein the convex boundary is located radially outward of the main loop and the concave boundary is located radially inward of the main loop.

11. The device of claim 8, wherein the non-circular cross-sectional shape is crescent-shaped, kidney-shaped, or a crescent-shaped form created by two intersecting ellipses.

12. The device as claimed in any one of claims 1-3, wherein the sensor control system is configured to adjust: The position and / or orientation of the at least one MR sensor relative to the mine ore bench or ore stockpile; and / or The position and / or orientation of the drive loop relative to the main loop.

13. The device of claim 12, further comprising an impedance monitor to monitor the resistive impedance at the feed terminal of the drive loop, wherein the sensor controls the system to adjust: Based on the monitored resistive impedance, the position and / or orientation of the at least one MR sensor relative to the mine ore step or ore stockpile; and / or The position and / or orientation of the drive loop relative to the main loop based on the monitored resistive impedance.

14. The device of claim 13, wherein the sensor control system adjusts the position and / or orientation such that the resistive impedance at the feed terminal of the drive loop is at a target resistive impedance.

15. The device of claim 14, wherein the sensor control system adjusts the position and / or orientation of the at least one MR sensor relative to the mine ore step or ore stockpile such that the resistive impedance at the feed terminal of the drive loop is within a predetermined resistive impedance range, and subsequently adjusts the position and / or orientation of the drive loop relative to the main loop such that the resistive impedance at the feed terminal of the drive loop is at the target resistive impedance.

16. The device of claim 12, further comprising a displacement monitor for monitoring displacement between the at least one MR sensor and the mine ore bench or ore stockpile.

17. The device of claim 16, wherein the sensor control system adjusts the position and / or orientation based on the monitored displacement.

18. The device of claim 17, wherein the sensor control system adjusts the position and / or orientation based on the monitored displacement to maintain a fixed interval between the mine ore step or ore stockpile and the main loop.

19. The device as claimed in any one of claims 1-3, comprising a reflector positioned above the main loop, the reflector being configured to reduce upward radiation and magnetic near-field from the mine ore steps or ore stockpile.

20. The device according to any one of claims 1-3, comprising a passive loop located above the main loop or in the plane of the main loop, the passive loop suppressing external electromagnetic interference in the main loop.

21. The device of claim 20, further comprising a reflector positioned above the main loop, the reflector being configured to reduce upward radiation and magnetic near-field from the mine ore step or ore stockpile, wherein the reflector is located between the main loop and the passive loop.

22. The device of claim 20, wherein the passive loop has a lumped capacitance impedance that can be adjusted by the sensor control system to optimize the suppression of external electromagnetic interference in the main loop.

23. The device according to any one of claims 1-3, further comprising a noise monitor to monitor the RF noise voltage at the feed terminal of the drive loop.

24. The device of claim 22, further comprising a noise monitor to monitor RF noise voltage at the feed terminal of the drive loop, wherein the sensor control system is configured to adjust the lumped impedance of the passive loop capacitors based on the monitored RF noise voltage to minimize the RF noise voltage at the feed terminal of the drive loop.

25. The device as claimed in any one of claims 1-3, comprising a resistor loop magnetically coupled to the main loop and terminated with a resistor.

26. The device of claim 25, wherein the sensor control system is configured to adjust the orientation of the resistor loop relative to the main loop.

27. The device of claim 26, further comprising an impedance monitor to monitor resistive impedance at the feed terminal of the drive loop, wherein the sensor control system is configured to adjust the orientation of the resistive loop relative to the main loop based on the monitored resistive impedance, such that the resistive impedance at the feed terminal of the drive loop is at a target resistive impedance.

28. The device according to any one of claims 1-3, comprising an insert radially positioned within the main loop in the plane of the main loop.

29. The device of claim 28, wherein the insert is an oblate spheroid.

30. The device according to any one of claims 1-3, wherein the mobile platform comprises a chassis having wheels or sliders.

31. The device as claimed in any one of claims 1-3, wherein the mobile platform is towed by a vehicle.

32. The device as claimed in any one of claims 1 to 3, wherein the mobile platform is self-motorized.

33. The device as claimed in any one of claims 1-3, wherein the mobile platform is an autonomous system programmed to mark predefined areas on a mine ore step.

34. The device as claimed in any one of claims 1-3, comprising a platform control system.

35. The apparatus of claim 34, wherein the platform control system is configured to control the movement of the mobile platform on the mine ore step or ore stockpile, such that a portion of the mine ore step or ore stockpile can be relatively moved through the platform area of ​​the mobile platform or can be positioned within the platform area of ​​the mobile platform.

36. The device of claim 35, wherein the platform control system is configured to control the information transfer between the device and one or more other components of the mining environment.

37. The apparatus of any one of claims 1-3, wherein, in order to control the sensitivity of the at least one MR sensor as a function of distance from the sensor to the mine ore bench or ore stockpile, the sensor control system is configured to: At least one RF pulse sequence is controlled to be applied to the MR sensor, and at least one corresponding analysis method is used to analyze the MR response signal from the mine ore bench or ore stockpile, wherein the at least one RF pulse sequence and its corresponding analysis method have a corresponding predetermined sensitivity distribution curve. The analysis of the MR response signal is used to measure the weighted corresponding sensitivity distribution curve; and The sensitivity distribution curves are used to weight and estimate the depth-dependent mineral concentration in the mine ore benches or ore stockpiles.

38. The apparatus of any one of claims 1 to 3, wherein, in order to control the sensitivity of the at least one MR sensor as a function of distance from the sensor to the mine ore bench or ore stockpile, the sensor control system is configured to: The application of a first RF pulse sequence to the MR sensor is controlled, and a corresponding first analysis method is used to analyze the first MR response signal from the mine ore bench or ore stockpile, wherein the first RF pulse sequence and the corresponding first analysis method have corresponding first predetermined sensitivity distribution curves. One or more additional RF pulse sequences are controlled to be applied to the MR sensor, and one or more corresponding additional analysis methods are used to analyze one or more additional MR response signals from the mine ore bench or ore stockpile, wherein each of the one or more additional RF pulse sequences and the one or more corresponding additional analysis methods has a corresponding additional predetermined sensitivity distribution curve. The analysis of the first MR response signal and the other MR response signal is used to measure the corresponding first sensitivity distribution curve weight and the other sensitivity distribution curve weight. The first sensitivity distribution curve is weighted and the other sensitivity distribution curves are weighted and summed to create a preferred spatial sensitivity distribution curve weighting; and The preferred spatial sensitivity distribution curve is used to weight the mineral concentration varying with depth in the mine ore bench or ore stockpile.

39. A method for measuring ore in a mine bench or ore yard using the equipment described in any of the preceding claims.

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