Equipment for measuring ore in mining transport vehicles

Abstract

An apparatus for measuring ore in a mining transport vehicle is disclosed, the apparatus comprising: a gate defining a gate area in which a transport vehicle carrying ore can be located or moved through the gate area; and at least one magnetic resonance (MR) sensor included in the gate. The MR sensor comprises a main circuit and a drive circuit located above the main circuit. A magnetic resonance sensor control system is provided and configured to control at least one of: positioning of the at least one MR sensor relative to the gate area and / or ore charge; positioning of elements included in the MR sensor relative to each other; electromagnetic suppression characteristics of the at least one MR sensor; and / or sensitivity of the at least one MR sensor as a function of the distance of the sensor from the ore charge.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Australian Provisional Patent Application No. 2019904927 filed on December 24, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to an apparatus and method for measuring ore on mining trucks and other mobile vehicles used to transport ore. Background Art

[0004] In mining, ore can be extracted underground or in open pits. In order to physically extract the ore for processing, various parts of the ore body are first blasted. The blasted ore, which usually has a larger maximum size of ore particles (usually up to 1m), is loaded into transport vehicles using shovels or other loaders. Transport vehicles are used to transport the ore to a variety of possible destinations for further processing. Destinations can include, for example, waste dumps, low-grade ore storage piles, high-grade ore storage piles, leach pads, primary crushers, or transfer stations. Transport vehicles can include, for example, trucks, underground load-haul-dump (LHD) vehicles, or other types of vehicles used to transfer discrete, large quantities of ore.

[0005] The chosen destination for the transport vehicle depends on the characteristics of the ore. One important characteristic is the elemental or mineral grade (concentration) of the ore. For example, ore with very low grades of the target economic mineral may be sent to a waste dump. Alternatively, the grade of other elements or minerals may determine the destination. For example, arsenic is a detrimental element. Ore determined to be high in arsenic mineralogy may be diverted to waste or another destination that allows for specialized processing.

[0006] Currently, in almost all mining operations, the destination of a transport vehicle is predetermined before loading the ore. The destination may be determined by analyzing pre-existing data associated with the ore characteristics (e.g., data contained in a block model). A block model is a spatially discrete representation of ore parameters (such as grade) in a portion of a deposit where mining is planned. In a block model, ore parameters are assigned to individual voxels of the ore. The size of each voxel or block varies depending on the type of mining and deposit, but a typical size for a large open pit mine may be 10,000 tons of ore. Block models are generally developed on a statistical basis by analyzing limited ore sample data. Sampling may be provided by mine planning drilling and assaying, or mine-scale sampling and assaying. The above-described ore recovery and block modeling methods are well known in the mining industry.

[0007] However, the data associated with each block in a block model is typically only available for the entire block size. Depending on the level of grade heterogeneity within the block, different sub-batches within the block may have ore parameters that differ significantly from the average block value. Grade estimates associated with batches smaller than the block size will have a lower confidence level, so that grade estimates for relatively small batches of ore carried by transport vehicles may have high uncertainty. Therefore, in general, ore grade variations in small batches (characterized by transport vehicle loading) may lead to incorrect allocation of ore destinations. For example, a particular batch of ore in a transport vehicle may correspond to a waste grade, but is sent to a processing destination intended for higher grade ore based on the block data. This misallocation has a negative impact on mining economics.

[0008] By using sensors to measure the grade of an element or mineral in a haul vehicle before determining the vehicle's destination, there is an opportunity to improve the mining process. By measuring the grade of the actual batch in the haul vehicle, the correct destination can be assigned based on the measurement, leading to an overall reduction in misassignments of haul vehicles and improved mine economics. Therefore, it would be beneficial if the grade of ore minerals on a truck could be measured.

[0009] Examples of transport vehicle sensing include applications in uranium and iron ore mining. For example, Srinivas et al. 1 describes the use of radiation sensing configured in a portal to detect uranium daughter isotopes to quantify uranium grade on a truck. Another known example provided by Temnikov et al. 2 The use of radiation sensing on mining machinery including trucks is similarly described. In other known examples, such as Krukka et al., 3 The detection of phosphorus grade in iron ore using a laser induced fluorescence (LIF) method is described, wherein an underground load haul dump (LHD) vehicle is located beneath a LIF sensing station with the goal of directing ore destination based on measurements of phosphorus grade in the iron ore.

[0010] The examples given above can be considered as "gate type" implementations. Other transport vehicle sensing implementations (besides gates) are also possible. For example, sensors can be mounted on the body of a transport vehicle, close to the vehicle ore batching, to measure the ore load of the transport vehicle.

[0011] In order to reliably determine the haul vehicle ore grade, the measurements must sample a sufficient portion of the haul vehicle load to provide a representative grade estimate. As the ore becomes more heterogeneous, a larger portion of the haul vehicle load must be measured to provide a reliable estimate.

[0012] Any discussion of documents, acts, materials, devices, articles of manufacture or the like included in this specification is not to be taken as an admission that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present disclosure as they existed before the priority date of each of the appended claims. Summary of the invention

[0013] According to one aspect of the present disclosure, there is provided an apparatus for measuring ore in a mining transport vehicle, the apparatus comprising:

[0014] a gate defining a gate area in which a transport vehicle carrying ore can be located or can move through the gate area,

[0015] at least one magnetic resonance (MR) sensor included in the gate, the MR sensor comprising:

[0016] a main circuit, which may be located in the gate area above or on the charge of ore carried by the transport vehicle,

[0017] a drive loop located above the main loop and electrically isolated from and magnetically coupled to the main loop, wherein a radio frequency (RF) transmitter is coupleable to a feed terminal of the drive loop to drive an RF drive current in the drive loop, and an RF receiver is coupleable to the drive loop to monitor an RF response current in the drive loop;

[0018] The device also includes:

[0019] A magnetic resonance sensor control system configured to control at least one of:

[0020] positioning of the at least one MR sensor relative to the gate area and / or ore batch;

[0021] the positioning of elements included in the MR sensor relative to each other;

[0022] electromagnetic suppression properties of the at least one MR sensor; and / or

[0023] The at least one MR sensor has a sensitivity that varies with the distance of the sensor from the ore charge.

[0024] In some embodiments, the main loop may include a plurality of conductive segments and capacitors located between the conductive segments. The capacitors may be evenly spaced along the main loop, and the capacitance of each capacitor may be substantially the same. In some embodiments, the capacitance of at least one of the capacitors of the main loop is adjustable. In some embodiments, the sensor control system is configured to adjust the capacitance of at least one of the capacitors of the main loop.

[0025] In some embodiments, the device further comprises an impedance monitor for monitoring a reactive impedance at the feed terminal of the drive loop. The sensor control system may be configured to adjust the capacitance based on the monitored reactive impedance. In some embodiments, the sensor control system may be configured to adjust the capacitance so that the reactive impedance at the feed terminal of the drive loop is at a target reactive impedance.

[0026] In some embodiments, the conductive segments and capacitors of the main loop may extend along an annular path, and in a cross section in a plane perpendicular to the annular path, the conductive segments may have a non-circular cross-sectional shape. In some embodiments, the non-circular shape may be a shape having a convex boundary and an opposite concave boundary. The convex boundary may be radially outside the main loop, and the concave boundary may be radially inside the main loop. In some embodiments, the non-circular shape may be a crescent shape, a kidney shape, or a crescent shape formed by two intersecting ellipses.

[0027] In any of the embodiments disclosed herein, the sensor control system may be configured to adjust at least one of: (i) the position and / or orientation of the at least one MR sensor relative to the ore charge; and (ii) the position and / or orientation of the drive circuit relative to the main circuit. For example, the sensor control system may be configured to control the movement of the entire MR sensor or at least the main circuit and drive circuit of the MR sensor so that it is closer to or farther away from the ore charge. Additionally or alternatively, the sensor control system may be configured to control the movement of the main circuit and the drive circuit so that they are closer to each other or farther apart. To achieve movement and orientation changes, the device may include one or more motion actuators, such as linear actuators controlled by motors, pneumatic devices, hydraulic devices, or otherwise.

[0028] The device may include an impedance monitor for monitoring the resistive impedance at the feed terminals of the drive loop, and the sensor control system may be configured to adjust the position and / or orientation based on the monitored resistive impedance as described above. In some embodiments, the sensor control system may be adapted to adjust the position and / or orientation so that the resistive impedance at the feed terminals of the drive loop is at a target resistive impedance.

[0029] In some embodiments, the sensor control system may be configured to adjust the position and / or orientation of the MR sensor relative to the ore charge so that the resistive impedance at the feed terminals of the drive circuit 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 circuit relative to the main circuit so that the resistive impedance at the feed terminals of the drive circuit is at a target resistive impedance.

[0030] In some embodiments, the apparatus may further include a displacement monitor for monitoring displacement (e.g., change in position and / or orientation) between the at least one MR sensor and the ore charge. 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 spacing between the ore charge and the main circuit.

[0031] In any of the embodiments disclosed herein, the apparatus may include a reflector located above the primary loop, the reflector being configured to reduce radiation and magnetic near fields from the ore charge in an upward direction.

[0032] In any of the embodiments disclosed herein, the device may include a passive loop located above the main loop 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.

[0033] In some embodiments, the reflector is located between the primary loop and the passive loop.

[0034] In some embodiments, the passive loop has a capacitive lumped impedance that is adjustable by the sensor control system to optimize suppression of external electromagnetic interference in the primary loop.

[0035] In embodiments disclosed herein, the device may further include a noise monitor for monitoring an RF noise voltage at the feed terminal of the drive loop. In some embodiments, the sensor control system may be configured to adjust the capacitive lumped impedance of the passive loop based on the monitored RF noise voltage to minimize the RF noise voltage at the feed terminal of the drive loop.

[0036] In any of the embodiments disclosed herein, the device may further include a resistive loop magnetically coupled to the main loop and terminated with a resistor. 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 for monitoring 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 so that the resistive impedance at the feed terminal of the drive loop is at the target resistive impedance.

[0037] In embodiments disclosed herein, the apparatus may further comprise an insert radially inside the primary loop in the plane of the primary loop. In some embodiments, the insert is an oblate spheroid.

[0038] In some embodiments, the transport vehicle is a truck, a load-haul-dump (LHD) vehicle, a dump truck, a van, or a cart.

[0039] In some embodiments, ore measurements may include measuring ore mineral quality and / or ore grade.

[0040] In some embodiments, the apparatus includes a gate control system. The gate control system may be configured to control movement of the transport vehicle through the gate area of ​​the gate. In some embodiments, the gate control system may be configured to control the transmission of information between the apparatus and one or more other components of a mining environment.

[0041] In another aspect of the present disclosure, there is provided a method of measuring ore in a mining haulage vehicle using an apparatus according to any embodiment disclosed herein.

[0042] As indicated, the sensor control system may be configured to control the sensitivity of the at least one MR sensor in dependence upon the distance of the sensor from the ore charge. The sensitivity of the at least one MR sensor may be identified in accordance with a "sensitivity profile", which is the sensitivity of the at least one MR sensor as a function of the distance of the sensor from the ore charge for one or more RF pulse sequences applied to the MR sensor and for one or more associated analytical methods (masking).

[0043] Relatedly, in some embodiments, various apparatus and methods are disclosed in which one or more predetermined sensitivity distributions of an MR sensor are determined for one or more RF pulse sequences applied to the MR sensor and for one or more associated analysis methods (masking). Masks may be applied to the time domain MR signals to prioritize responses for diagnosing different depths in an ore charge. For a particular ore charge to be analyzed, a weighting of each sensitivity distribution may be measured. For example, a sensor control system may use the one or more sensitivity distribution weightings to estimate mineral concentrations in an ore charge as a function of depth.

[0044] For example, in one embodiment, the sensor control system of the device may be configured to:

[0045] controlling application of at least one RF pulse sequence to the MR sensor and analyzing MR response signals from the ore charge using at least one corresponding analysis method, wherein the at least one RF pulse sequence and its corresponding analysis method have corresponding predetermined sensitivity profiles,

[0046] using analysis of the MR response signals to measure corresponding sensitivity distribution weights; and

[0047] The sensitivity distribution weights are used to estimate the concentration of minerals in the ore batch as a function of depth.

[0048] In some embodiments, disclosed are apparatus and methods utilizing or including:

[0049] i. determining a first predetermined sensitivity distribution of the MR sensor for a first RF pulse sequence and a first associated analysis method (masking) applied to the MR sensor;

[0050] ii. determining one or more further predetermined sensitivity distributions of the MR sensor for one or more further RF pulse sequences and one or more associated analysis methods (masking) applied to the MR sensor;

[0051] iii. providing said first RF pulse sequence to said MR sensor and analysing a resulting first MR response signal from a charge of ore using a first associated analysis method to measure a first sensitivity distribution weighting of a first sensitivity distribution;

[0052] iv. providing the one or more further RF pulse sequences to the MR sensor and analysing one or more resulting further MR response signals from the ore charge using the one or more further associated analysis methods to measure one or more further sensitivity distribution weightings of the one or more further sensitivity distributions;

[0053] v. adding the sensitivity distribution weights measured in step (iii) and step (iv) to produce a preferred spatial sensitivity distribution weight; and

[0054] vi. using the preferred spatial sensitivity distribution weights obtained in step (v) to estimate the concentration of minerals in the ore batch as a function of depth.

[0055] For example, in one embodiment, the sensor control system of the device may be configured to:

[0056] controlling application of a first RF pulse sequence to the MR sensor and analyzing a first MR response signal from the ore charge using a corresponding first analysis method, wherein the first RF pulse sequence and the corresponding first analysis method have a corresponding first predetermined sensitivity profile,

[0057] controlling application of one or more further RF pulse sequences to the MR sensor and analysing one or more further MR response signals from the ore charge using one or more corresponding further analysis methods, wherein the one or more further RF pulse sequences and the one or more corresponding further analysis methods each have a corresponding further predetermined sensitivity profile,

[0058] using said analysis of said first and further MR response signals to measure corresponding first and further sensitivity distribution weightings;

[0059] summing the first sensitivity distribution weighting with the further sensitivity distribution weighting to produce a preferred spatial sensitivity distribution weighting; and

[0060] The preferred sensitivity distribution weighting is used to estimate the mineral concentration in the ore batch as a function of depth.

[0061] In general, it will be appreciated that the sensor control system may include a plurality of 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 distributions, sensitivity distribution weights, impedance values ​​or others). The modules and storage devices may be implemented using one or more processing devices and one or more data storage units, which may be in one location or distributed in multiple locations and interconnected by one or more communication links.

[0062] In addition, the module may be implemented by a computer program or program code including program instructions. Computer program instructions may include source code, object code, machine code or any other stored data that can be operated to cause the processor to perform the steps described. The computer program can be written in any form of programming language (including compiled or interpreted languages) and can be deployed in any form, including as a stand-alone program or as a module, component, subroutine or other unit suitable for use in a computing environment. The data storage device may include a non-transitory computer-readable memory medium, which includes instructions that cause the processor to perform the steps described herein. The data storage device may include a suitable computer-readable medium, such as volatile (e.g., RAM) and / or non-volatile (e.g., ROM, disk) memory or other.

[0063] Throughout this specification, the word "comprise" or variations such as "comprising" or "including" will be understood to imply the inclusion of stated elements, integers or steps, or groups of elements, integers or steps but not the exclusion of any other elements, integers or steps, or groups of elements, integers or steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0065] Figure 1 shows a component block diagram of an apparatus for measuring ore in a mining transport vehicle according to an embodiment of the present disclosure;

[0066] Figure 2 shows a side schematic view of an apparatus for measuring ore in a mining transport vehicle according to an embodiment of the present disclosure;

[0067] Figure 3a shows a cross-sectional view of a magnetic resonance sensor according to an embodiment of the present disclosure;

[0068] Figure 3b Shows Figure 3a A plan view of a magnetic resonance sensor;

[0069] Figure 3c shows a cross-sectional view of a magnetic resonance sensor according to an embodiment of the present disclosure;

[0070] Figure 4 A schematic diagram showing a magnetic resonance sensor and a sensor control system according to an embodiment of the present disclosure is shown;

[0071] Figure 5c A circular cross section ( Figure 5a ) and non-circular cross-sections ( Figure 5b )’s normalized on-axis field per unit current of the main loop;

[0072] Figure 6 A schematic diagram showing a magnetic resonance sensor and a sensor control system according to an embodiment of the present disclosure is shown;

[0073] Figure 7 illustrates the functionality of a loop forming an RF gradiometer according to an embodiment of the present disclosure;

[0074] Figure 8a shows a cross section of the main loop with no inserts in the main loop plane, and Figure 8b The corresponding calculated normalized RF magnetic field profile is shown;

[0075] Figure 9a showing a cross section of the main loop with an inset in the plane of the main loop; and Figure 9b The corresponding calculated normalized RF magnetic field profile is shown;

[0076] Fig.10 Shows Figure 8a The main loop without inserts (blue trace) and Figure 9a Normalized on-axis field per unit current of the main loop with insert (black trace), and the field generated by eddy currents on the surface of the insert (red trace)

[0077] Fig.11 shows an MR sensor suspended above a half-space, where a sample comprising a thin disk can be located at different displacements (z) from the sensor in a plane parallel to the sensor face;

[0078] Figures 12a to 12c shows three different sensitivity distributions obtained for three different pulse sequences and analysis methods; and

[0079] Figure 13a to Figure 13b Shown are masks used to extract signal power at different times in the FID waveform corresponding to (a) early analysis and (b) late analysis. DETAILED DESCRIPTION

[0080] One or more embodiments of the present disclosure may provide, at least in part, an apparatus suitable for measuring ore while it is carried in the form of an ore charge in a mining transport vehicle and using magnetic resonance (MR) techniques.

[0081] Magnetic resonance is a type of radio frequency (RF) spectroscopy used in areas such as fundamental studies of atomic and molecular bonding and routine laboratory characterization of materials and medical imaging. Most applications involve the use of conventional nuclear magnetic resonance (NMR) in the laboratory to measure hydrogen and carbon nuclei for the analysis of organic compounds. Other less common classes of magnetic resonance include nuclear quadrupole resonance (NQR) and NMR in magnetically ordered materials. These less common classes are applicable only to the solid state but offer several important measurement advantages. First, in these cases, no external static magnetic field needs to be applied to define and measure the resonances. Second, the resonance frequency is strongly dependent on chemical bonding and crystal structure and is therefore often highly specific to a particular crystalline phase. For 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 external static magnetic field.

[0082] In most types of MR, an RF magnetic field (usually the near field region of an inductive coil or coil set) is applied to the material to be analyzed. In practice, the near field region can be defined as a region that includes both the interior of the inductive sensor and the region around the sensor extending to a distance equal to several diameters of the sensor.

[0083] The measurement sequence in the pulsed MR method that can be applied in the device according to the present disclosure involves an excitation phase followed by a detection phase. In the excitation phase, a pulsed RF current is driven in the sensor to irradiate the material located in the near-field region with the RF field. The RF current is driven by a radio frequency transmitter coupled to the sensor. The irradiation causes the generation of dynamic nuclear magnetization of the target nuclei in the material, thereby generating an associated RF response field. After the RF excitation current is switched off, the response field may remain large in amplitude.

[0084] If the RF response field is generated in the near field region of the sensor coil (the same induction coil used for excitation, or a different coil), a voltage may be generated at the output terminals of the sensor, which can then be used to detect the RF response field using an RF receiver to detect the signal (and noise) voltage at the sensor output terminals. This corresponds to the detection phase of the measurement sequence. Therefore, both the transmitter and receiver are coupled to the sensor, but usually at different times during the measurement process. The coupling of the transmitter or receiver to the sensor can be controlled using an RF switch. For detection based on Faraday's law, the terminal voltage is proportional to the time rate of change of the magnetic flux passing through the aperture defined by the sensor coil. The magnitude 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. With auxiliary knowledge of the mass loading within the sensing volume, the concentration and grade of the material can also be determined.

[0085] For example, the mineral mass M can be calculated according to the following formula:

[0086] M=a×S

[0087] where a is the calibration factor and S is the magnetic resonance signal voltage.

[0088] Grade G can be calculated according to the following formula:

[0089]

[0090] where b is a fixed calibration factor and M o is an estimate of the mass of ore in the sensing area. o It may be assumed to be a fixed value, or a value determined by measuring the distribution of ore on board the transport vehicle.

[0091] Known applications using MR techniques generally involve measuring relatively small samples (e.g., sample volumes less than 1 L), and are performed in a controlled environment, such as a fully electromagnetically shielded sensor, or in a magnetic resonance imaging (MRI) apparatus that is also fully shielded. In this regard, electromagnetic (EM) shielding is required to avoid poor signal-to-noise ratios due to external electromagnetic disturbances that interfere with the detection of MR signals.

[0092] Figure 1 An apparatus 100 for measuring ore in a mining transport vehicle 201 according to an embodiment of the present disclosure is shown. The apparatus 100 comprises a gate 200, at least one magnetic resonance (MR) sensor 300 included in the gate 200, a magnetic resonance sensor control system 400 and an optional gate control system 500. Figure 2 The gate defines a gate area 202. The gate 200 is a mechanical structure, for example having a frame, which can accommodate the mechanical integration of at least one magnetic resonance sensor 300 and the passage of the transport vehicle 201 through or at least partially near the gate when the transport vehicle 201 carries ore material (ore batching), such as Figure 2 as shown in .

[0093] The sensor control system 400 is generally configured to control features of the device to facilitate the ability of the magnetic resonance sensor to operate in a gate environment and / or to make more reliable or more accurate measurements using the magnetic resonance sensor 300. The sensor control system 400 may control, for example, at least one of: the positioning of the at least one MR sensor 300 relative to the zone of the gate 200 and / or relative to the ore charge; the positioning of elements included in the MR sensor 300 relative to each other; the electromagnetic rejection characteristics of the at least one magnetic resonance sensor 300; and / or the sensitivity of the at least one magnetic resonance sensor 300 as a function of the distance of the sensor 300 from the ore charge.

[0094] The gate control system 500 may control, for example, at least one of: movement of the transport vehicle 201 through the gate area 202 of the gate 200 (e.g., stopping and starting the movement); and the transmission of information between the equipment 100 and one or more other components of the mining environment. In practice, the sensor control system 400 and the gate control system 500 may be integrated into a wider control system of the equipment, or remain as separate control system elements.

[0095] The gate 200 has physical dimensions that define the volume or area of ​​the gate area 202. Preferably, the gate area 202 is large enough to accommodate a typical transport vehicle 201 when carrying ore batches. In some embodiments, the gate 200 may be adapted to allow or cause the transport vehicle 201 to be transported from an entrance 203 of the gate area 202 to an exit 204 of the gate area, thereby defining a transport vehicle transport path, i.e., the entrance 203 to the exit 204.

[0096] In some embodiments, a transport vehicle 201 carrying ore material may be continuously moved along a vehicle transport path through the gate area 202. Alternatively or additionally, the transport vehicle 201 may be parked at a designated location within the gate area 202. Thus, during the measurement of ore material carried on the transport vehicle 201, the transport vehicle 201 may be stationary and / or mobile. The apparatus 100 may include a conveyor or other traction system for moving the transport vehicle 201, wherein the movement of the transport vehicle 201 by the conveyor is controlled by the gate control system 500. Alternatively, the transport vehicle may be self-propelled through the gate area or moved by other means.

[0097] Typically, the apparatus 100, including the gate 200 and / or gate area 202, may be adapted for measuring ore carried by a variety of different transport vehicles, including those capable of self-propelled transport vehicles such as trucks, trains or load-haul-dump (LHD) vehicles, or dump trucks, vans or carts or the like, which may be located within the gate area 202 for ore measurement and moved by the apparatus 100 or other means.

[0098] For example, a transport vehicle may carry a load ranging from a few tons to 350 tons. In order to make a representative measurement of the ore material, it may be necessary to measure a potentially large ore volume (e.g., many cubic meters). The 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 the present disclosure can provide bulk measurements of ore carried by a transport vehicle.

[0099] For large volume, batch, measurements, the ore batch can be approximated as the ore half-space.

[0100] To optimize detection of ore at great distances from the sensor or otherwise, aspects of the apparatus comprising at least one MR sensor of apparatus 100 may be optimized, possibly in combination.

[0101] For example, the apparatus 100 may be configured so that the available RF power can be used to maximize the radio frequency (RF) field at large distances from the MR sensor 300. Below a certain field strength threshold, the inductive response field drops off exponentially. Increasing the RF field strength at depth can increase the sensing volume of the ore batch.

[0102] Additionally, the MR sensor 300 may be configured to account for electrical impedance changes associated with ore and other mechanical proximity.

[0103] In addition, the MR sensor 300 may be configured to reject potentially high levels of external electromagnetic interference. For measuring ore batches carried by haulage vehicles using a gate structure, it may be impractical to completely shield the haulage vehicle during measurement, for example, due to the need for gate entry and exit points. At best, only partial shielding may be applied. Using a gate arrangement to measure ore carried by haulage vehicles may be considered an "open system" in which complete electromagnetic (EM) shielding techniques / equipment may not be applicable, and therefore other means of suppressing electromagnetic interference may be particularly advantageous.

[0104] It may also be advantageous for the MR sensor 300 to be configured to return uniformly weighted measurements of the charge of ore carried by the transport vehicle in the gate area 202. That is, in some embodiments, it may be preferred that the MR sensor 300 is not overly sensitive to non-uniform mineral or elemental grade distributions. For example, this may be applicable in situations where high-grade ore material very close to the sensor results in an overestimation of the overall grade because the sensor sensitivity is greater in the spatial region close to the MR sensor 300.

[0105] As discussed in more detail below in Example 4, different configurations of the pulse sequence applied to the MR sensor 300 may change the characteristics of the spatial sensitivity of the MR sensor 300 in the measurement region 205 (ore half-space). In embodiments of the present disclosure, the pulse sequence and signal analysis methods may be modified to preferentially suppress the sensitivity of the MR sensor 300 at regions very close to (e.g., adjacent to) the MR sensor 300, while the sensitivity is relatively unaffected at regions farther from the MR sensor 300.

[0106] One or more predetermined sensitivity profiles of the MR sensor 300 may be determined for one or more RF pulse sequences applied to the MR sensor 300 and for one or more associated analysis methods (masks). Masks may be applied to the time domain MR signals to optimize responses for diagnosing different depths in the ore charge. For a particular ore charge to be analyzed, a weight for each sensitivity profile may be measured. One or more sensitivity profile weights may be used to estimate mineral concentrations in the ore charge as a function of depth.

[0107] In one embodiment, the sensor control system 400 of the device 100 is configured to:

[0108] controlling application of at least one RF pulse sequence to the MR sensor 300 and analyzing MR response signals from the ore charge using at least one corresponding analysis method, wherein the at least one RF pulse sequence and the at least one corresponding analysis method each have a corresponding predetermined sensitivity profile,

[0109] using analysis of the MR response signal to measure a corresponding sensitivity distribution weight; and

[0110] The concentration of minerals in the ore batch is estimated as a function of depth using sensitivity distribution weighting.

[0111] In some embodiments, for example, according to the methods described in more detail in Example 4, an apparatus or associated method for measuring an ore (including, for example, measuring a mineral concentration or grade) may utilize or include the following:

[0112] i. determining a first predetermined sensitivity distribution of the MR sensor 300 for a first RF pulse sequence and a first associated analysis method (masking) applied to the MR sensor 300;

[0113] ii. determining one or more additional predetermined sensitivity distributions of the MR sensor 300 for one or more additional RF pulse sequences and one or more associated analysis methods (masking) applied to the MR sensor 300;

[0114] iii. providing a first RF pulse sequence to the MR sensor 300 and analysing the resulting MR response signal from the ore charge using a first associated analysis method to measure a first sensitivity distribution weighting of a first sensitivity distribution;

[0115] iv. providing the one or more further RF pulse sequences to the MR sensor 300 and analysing one or more resulting MR response signals from the ore charge using the one or more further associated analysis methods to measure one or more further sensitivity distribution weightings of the one or more further sensitivity distributions;

[0116] v. adding the sensitivity distribution weights measured in step (iii) and step (iv) to produce a preferred spatial sensitivity distribution weight; and

[0117] vi. using the preferred spatial sensitivity distribution weights obtained in step (v) to estimate the concentration of minerals in the ore batch as a function of depth.

[0118] For example, in one embodiment, the sensor control system 400 of the device 100 is configured to:

[0119] controlling application of a first RF pulse sequence to the MR sensor 300 and analyzing a first MR response signal from the ore charge using a corresponding first analysis method, wherein the first RF pulse sequence and the first corresponding analysis method have corresponding first predetermined sensitivity profiles,

[0120] controlling application of one or more further RF pulse sequences to the MR sensor 300 and analyzing one or more further MR response signals from the ore charge using one or more further corresponding analysis methods, wherein the one or more further RF pulse sequences and the one or more further corresponding analysis methods each have a corresponding further predetermined sensitivity profile,

[0121] using analysis of the first MR response signal and the further MR response signal to measure corresponding first and further sensitivity distribution weightings;

[0122] summing the first sensitivity distribution weight and the further sensitivity distribution weight to produce a preferred spatial sensitivity distribution weight; and

[0123] The preferred sensitivity distribution weightings are used to estimate the mineral concentration in the ore charge as a function of depth.

[0124] Reference now Figure 3a and Figure 3b At least one MR sensor 300 according to one embodiment of the present disclosure is described in more detail. Figure 3a As shown, the magnetic resonance sensor 300 includes a main circuit 301 located above the ore charge or on the top of the ore charge placed on the transport vehicle 201 and an auxiliary circuit (drive circuit 302) coaxially positioned with the main circuit 301 and located above the plane of the main circuit. The drive circuit 302 is electrically isolated from the main circuit 301 and magnetically coupled to the main circuit 301, and resonates in series at an appropriate frequency. The main circuit 301 resonates at a series resonance frequency that is substantially the same as the resonance frequency of the drive circuit (usually within a 2% error).

[0125] The drive loop 301 is fed by a radio frequency (RF) transmitter located at the drive loop feed terminal 3013. The RF drive current in the drive loop 302 excites the RF drive current in the main loop 301, generating an RF magnetic field in the measurement zone 205 of the apparatus 100, the RF magnetic field being suitable for changing the magnetization of the target nuclei in the ore carried by the transport vehicle 201. Typically, the measurement zone will at least partially intersect the vehicle transport path of the transport vehicle 201. The RF response current is excited in the main loop 301 by the magnetization precession of the target nuclei, and the RF response current in the main loop 301 causes a corresponding RF response current in the drive loop 302, which is monitored by a radio frequency receiver (not shown) coupled to the drive loop 302.

[0126] The main loop 301 of at least one magnetic resonance sensor 300 is adjusted to have a series resonant frequency, and at least one magnetic resonance sensor is adjusted to have an associated operating frequency suitable for magnetic resonance measurement of the target nucleus. Those skilled in the art will appreciate that the resonant absorption and emission of energy by the target nucleus as a whole may have a frequency distribution. The peak magnetic resonance frequency is defined as the mode of the frequency distribution. When the series resonant frequency is close to the peak magnetic resonance frequency, the operating frequency of the at least one magnetic resonance sensor 300 may be suitable for magnetic resonance measurement of the target nucleus.

[0127] The operating frequency is set close to the peak resonance frequency of the target nuclei, thereby increasing the sensitivity of the magnetic resonance sensor 300 to a small number of target nuclei by exciting a larger RF signal current in the main loop 301. For example, the operating frequency may be set so that the frequency of the excited RF current differs from the peak magnetic resonance frequency of the target nuclei by no more than two standard deviations (of the magnetic resonance frequency distribution of the target nuclei).

[0128] Turning attention in particular to the main loop 301, and referring to Figure 3a and Figure 3b , the main loop 301 is a planar loop (e.g., a single turn coil) located above or on top of the ore charge transporting the mining vehicle 201. The main loop 301 conducts RF current so that it is primarily in phase throughout the main loop. The RF current produces an RF magnetic field suitable for changing the magnetization of the target nuclei; such as by resonantly exciting the target nuclei to change the orientation of the net magnetization of the target nuclei as a whole. In addition, the main loop 301 is adjusted to have an RF signal current excited by the precession of the magnetization of the target nuclei in the ore material being analyzed.

[0129] The main loop 301 is divided into a discrete plurality of conductive sections 3011a-d separated by tuning capacitors 3012a-d. The capacitances of the tuning capacitors 3012a-d are substantially equal (e.g., differing by no more than 10% from each other) and are selected to cause the main loop 301 to be in series resonance. The division into sections 3011a-d is to achieve a substantially uniform RF current in the main loop 301. The uniform RF current optimizes near-field uniformity in the irradiated half-space of the ore charge. The division also minimizes the maximum voltage at points on the main loop 301 relative to the ore or other elements in the near-field region (i.e., near zone) of the electromagnetic field (EM) of the main loop 301 due to the non-uniform distribution of charge. This reduces RF loss mechanisms associated with non-uniform loop charge distribution, reduces the main loop resistance and allows for an increase in the RF field magnitude in the near-field region.

[0130] In some embodiments, at least one of the tuning capacitors 3011a - d is adjustable to allow modification of the series resonance of the main loop 301 .

[0131] Advantageously, the inductance of the main loop 301 is minimized without compromising the field generation in the measurement region 205. The quality factor of a loop is defined as the loop reactance divided by the loop resistance. With a fixed quality factor of the loop, a minimum inductance means a corresponding minimum loop resistance. In general, the main loop 301 can be considered to extend along a circular path.

[0132] In some embodiments, the shape of the cross-section of the main loop 301 (in a plane perpendicular to the loop path) can be circular, thereby providing a generally annular overall shape for the main loop 301. However, in the present disclosure, it has been advantageously recognized that different shapes (non-circular) of cross-sections of the main loop can also be utilized, for example, in order to minimize the inductance of the main loop 301.

[0133] The shaping of the main loop cross section reduces the inductance compared to a circular cross section of a ring. Figure 5c A comparison of the fields per unit current produced by primary loops having different cross-sectional shapes is shown, subject to 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 based solely on shape changes, and not due to modifications in the distance between the primary loop and the ore). Figure 5c In this paper, two trajectories are provided, one of which is from ( Figure 5a The normalized on-axis field is obtained by using the circular cross section / annular main loop, while the other trajectory is obtained by using ( Figure 5bFigure 1 shows the normalized on-axis field obtained for a non-circular shaped main loop. The field generated by the main loop is nearly identical for each case. However, there is a significant difference in the loop inductance for each case, as can be seen in Table 1 below. Despite having the same vertical dimensions and on-axis 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 beneficial for reducing sensor inductance and resistance.

[0134] Table 1- Figure 5a and Figure 5b The loop inductance of the loop cross-section geometry shown in

[0135] cross section Inductance(μH) Round 1.26 Non-circular 1.05

[0136] like Figure 5b As seen in FIG. 3 , a non-circular shape is a shape having a convex boundary 3015a and an opposite concave boundary 3015b. The convex boundary 3015a is at the radially outer side of the main loop, and the concave boundary 3015b is at the radially inner side of the main loop. A non-circular shape can be considered to be a kidney shape, a crescent shape, or a crescent shape formed by two intersecting ellipses. Other non-circular shapes are also possible.

[0137] Turning now to the drive circuit 302, the drive circuit 302 uses a plurality of capacitors 3022a-d to be serially resonant at the operating frequency and magnetically coupled to the main circuit 301. The mutual coupling of the drive circuit 302 and the main circuit 301 can be adjusted by changing the position of the drive circuit 302 relative to the main circuit 301. The variable position allows the real part of the input electrical impedance at the feed terminal 3013 to be modified. This can account for the variable electrical impedance imparted by the variable ore batch presentation on the transport vehicle 201.

[0138] refer to Figure 4 , the apparatus may include at least one impedance monitor 307 and an RF receiver 308. The impedance monitor 307 may monitor the reactive and / or resistive impedance at the feed terminals of the drive loop 302 and provide details of the monitored impedance to the sensor control system 400. The RF receiver 308 may detect the signal (and noise) voltage during the detection phase of the measurement sequence.

[0139] In some embodiments, the sensor control system 400 is configured to adjust the capacitance of at least one capacitor of the main loop 301, for example based on the monitored reactive impedance. This can be performed so 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 var-ohm.

[0140] In some embodiments, such as Figure 4As shown, the sensor control system 400 includes a displacement monitor 309 for monitoring the position, orientation and / or displacement between at least one MR sensor 300 and the ore charge. 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 spacing between the ore charge and the main loop 301 of the MR sensor 300.

[0141] 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 the ore charge. Alternatively or additionally, the sensor control system 400 may be configured to control the position and / or orientation of the drive circuit 302 relative to the main circuit 301. In some embodiments, the sensor control system adjusts the position and / or orientation based on the monitored resistance impedance. In some embodiments, the sensor control system 400 adjusts the position and / or orientation of at least one MR sensor 300 relative to the ore charge so that the resistance impedance at the feed terminal of the drive circuit 302 is within a predetermined resistance impedance range. The resistance impedance range may generally differ from the target feed terminal resistance impedance by less than 30%. Subsequently, the sensor control system 400 may adjust the position and / or orientation of the drive circuit relative to the main circuit so that the resistance impedance at the feed terminal of the drive circuit is at a target resistance impedance. The target resistance impedance is a fixed system impedance that is predetermined and selected for optimization of RF power transmission from the transmitter to the sensor. A typical target resistance impedance is 50 ohms.

[0142] It is advantageous to maintain a fixed and optimized electrical impedance at the (high power) drive loop feed terminal 3013. The position of the drive loop 302 may be set based on a measurement of the difference between the drive loop feed terminal input impedance and a target input impedance. The position of the drive loop 302 may vary based on a vertical or angular displacement.

[0143] Those skilled in the art will appreciate that the at least one MR sensor 300 may include other conductive elements, impedance monitors, actuators, combination circuits, inserts, reflectors, drive coils, and / or other reflectors / shields.

[0144] refer to Figure 3aIn some embodiments, at least one magnetic resonance sensor 300 further comprises a passive reflector 303, which may be coaxial with the main loop 301 and located 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 fields entering in a direction opposite to the measurement region 205 (i.e., opposite to the ore half-space). In some embodiments, the reflector is configured to reduce radiation and magnetic near fields in an upward direction from the ore charge. In some embodiments, as Figure 3a As shown, the reflector 303 can be a substantially flat, disk-shaped structure without an aperture. In an alternative embodiment, as shown in FIG. Figure 3c As shown, the reflector 303 ′ may be a dome-shaped structure without an aperture. In the case of a dome-shaped reflector 303 ′ structure, the concave surface of the dome faces the main loop 301 .

[0145] Still reference Figure 3a In some embodiments, at least one magnetic resonance sensor 300 may include a coaxially positioned sensor with the main loop 301 and as Figure 3a A passive loop 304 (single turn coil) is shown above the main loop 301 or in the plane of the main loop 301. The passive loop 304 is magnetically coupled to the main loop 301. The passive loop 304 has a specific selected capacitive lumped impedance inserted in series to provide suppression of external electromagnetic interference in the main loop 301. In some embodiments, the specific capacitive lumped impedance is changed, for example by the sensor control system 400 based on the measurement of the RF noise voltage at the feed terminal of the drive loop, so as to optimize the suppression of external electromagnetic interference / minimize the RF noise voltage. At least one MR sensor 300 may include a noise monitor for monitoring the RF noise voltage at the feed terminal of the drive loop 302. The RF receiver can be used as a noise monitor.

[0146] In some embodiments, the reflector 303 is located between the main loop 301 and the passive loop 304. In this regard, the reflector 303 can be used to reduce mutual coupling between the main loop and the passive loop 304, as discussed in more detail in Example 2 below.

[0147] In some embodiments, and as Figure 3a As shown in the embodiment of FIG. 1 , at least one MR sensor 300 includes a resistive loop 305 magnetically coupled to a main loop 301 and resistively terminated. The orientation of the resistive loop 305 can be modified relative to the main loop 301 to provide a change in the resistive impedance of the drive loop feed network. The resistive loop 305 can be used to modify the overall resistive losses in the magnetic resonance sensor 300 in order to control the RF current in the main loop 301.

[0148] In some embodiments, the sensor control system 400 is configured to adjust the orientation of the resistive loop 305 relative to the main loop 301. In these embodiments, the device 100 may include an impedance monitor for monitoring the resistive impedance at the feed terminals of the drive loop 302, and the sensor control system 400 may be configured to adjust the orientation of the resistive loop 305 relative to the main loop 301 based on the monitored resistive impedance. In this way, the resistive impedance at the feed terminals of the drive loop 302 can be placed or maintained at a target resistive impedance.

[0149] Still reference Figure 3a In some embodiments, at least one magnetic resonance sensor 300 includes a passive insert 306 located in the plane of the main loop 301 and inside the minimum radius of the main loop 301. The passive insert 306 can be a disk or elliptical structure without an orifice. In some embodiments, the passive insert 306 is an oblate spheroid. The outer surface of the insert can be composed of a material with high conductivity, such as copper. The inner portion of the insert can be composed of the same material as the outer surface or other materials.

[0150] According to the present disclosure, a passive insert 306 may be used to suppress RF fields in the immediate vicinity of the main loop 301, but configured to minimally affect RF fields at significant distances from the main loop 301. Thus, the passive insert 306 may be used to suppress eddy currents in the measurement zone 205 (i.e., the ore half-space) in the immediate vicinity of the main loop 301, so as to reduce the effective resistance of the main loop. Such a configuration may thereby increase the current in the main loop 301 and cause an overall increase in the RF field at locations distant from the main loop 301.

[0151] Another beneficial effect of the passive insert 306 may also be to flatten the MR sensitivity distribution in the measurement region 205 (ie the rock half-space) by reducing the local sensitivity in locations very close to the sensor.

[0152] refer to Figure 6 , the control system 400 may include actuators (600a-d) to modify the position and / or orientation of the magnetic resonance sensor 300 and elements within the magnetic resonance sensor 300 (including the main loop 301, the drive loop 302, the passive loop 304 and the resistive loop 305). The sensor control system may use measurement information for this purpose, including the complex impedance of the sensor drive loop feed terminals, the noise voltage at the sensor drive loop feed terminals (e.g. measured by a radio frequency receiver) and the distance between the front of the sensor and the ore carried in the transport vehicle (e.g. by means of ultrasonic or laser distance measurement methods).

[0153] Example 1 - Passive Loop ("Gradiometer") Functionality

[0154] 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 degree of RF interference suppression in one of the loops. The analysis can be started by assuming that the external interfering field contributes electromotive force ε1 and ε2 to loop 1 and loop 2, respectively. The electromotive force will be proportional to the corresponding loop area. In this analysis, loop 1 can be identified as the "main loop" and loop 2 is identified as the "passive loop", for example, according to the aforementioned embodiment. For example, according to the aforementioned embodiment and will be further discussed, a bowl-shaped or disc-shaped "passive reflector" can be inserted between loop 1 and loop 2, but is now omitted from the analysis. It is also assumed that ε1 and ε2 are in phase. This usually means that the distance between the loops is much smaller than the free space wavelength and is coupled to the same field polarization. Therefore, the ratio α=ε2 / ε1 is a positive real number. It is also assumed that the loop is physically smaller than the free space wavelength. It can be seen that the principle of lumped circuit analysis can be used to analyze the electromotive force caused by the external field and the scattered field from the other loop in each loop.

[0155] Each loop, when completely isolated from the other (mutual inductance M = 0), has the usual complex loop impedances in series around the loop paths of Z1 = r1 + jX1 and Z2 = r2 + jX2. These impedances encapsulate the internal loop resistance and inductance as well as the external inductance. They also include any terminal impedances that load the loop, in the form of tuning elements, and in the case of loop 1, the input impedance of the receiver that appears during the receive phase of the measurement. When M ≠ 0, the total emf ε in loop 1 can be expressed as T yes

[0156]

[0157] where β = ωM / X2, γ = r2 / X2. We seek to minimize |ε T To continue, note that the size of the numerator in (1) can be minimized by judicious choice of M and loop 2 termination:

[0158]

[0159] where the approximation for X2 holds for small |γ| and αωM>2r2. This particular choice of X2 yields:

[0160]

[0161] It is observed that by taking small |γ|, |ε T | has the potential to be greatly reduced. It must be verified that D is not small either. D can be rewritten as follows:

[0162]

[0163] To make further progress, we note that loop 1 will usually be operated very close to resonance, where Z1 is essentially purely real (X1 = 0) to allow efficient RF power coupling during the excitation phase of the measurement. Under this assumption, |D|>1 always holds.

[0164] As an example, the following parameters may be chosen (independently): α = 2, r2 / r1 = 2, |γ| = 0.1. Then β ~ -0.5 and |D| = 5.1. For these parameters, correct phasing of the scattered field is achieved and the RFI reduction factor according to equation (3) is 0.019 or 34 dB.

[0165] Finally, we can examine the impedance Z “seen” by the test voltage applied in series with loop 1 T (where equation (2) also applies), this takes into account the reflected impedance of loop 2, as this is the relevant impedance associated with the current drive in loop 1:

[0166]

[0167] where Z′1=r′1+jX′1 is the impedance of loop 1 when it is completely isolated, but the receiver circuit does not contribute to the loading of the loop. In practice, Z′1 is usually similar to Z1. Note that, depending on the parameters chosen, the impedance (Z T The real part of ( ) has only a small contribution. This condition ensures effective power coupling from the external drive circuit to loop 1. The loop 1 reactance is also only weakly affected. Therefore, in an area defined by a field pattern similar to the field pattern generated by a single completely isolated loop, loop 1 can excite a significant RF magnetic field for magnetic resonance measurement. By applying the reciprocity principle, the same loop is therefore able to receive signals generated in the same area. However, due to the arranged phasing and magnitude of the scattered fields, the RF interference (RFI) magnetic field with the same phase and magnitude passing through the two loops is significantly suppressed. Numerical analysis of the loop arrangement including free space radiation effects yields similar RFI suppression properties.

[0168] Thus, the provision of a passive loop, for example as described in the previous embodiments, may provide suppression of external electromagnetic interference in the main loop.

[0169] Example 2 - The role of a passive reflector

[0170] One role of the passive reflector is to reduce the RFI field impact on loop 1 (the main loop). This function is achieved in the absence of loop 2. Loop 1 is placed in an area of ​​reduced field, thereby reducing ε1 and providing a degree of RFI suppression.

[0171] Another role of the passive reflector is to reduce the mutual coupling between the main loop and the passive loop. The above analysis does not acknowledge that there may be practical limitations in achieving the parameters selected for RFI suppression. For example, in the above analysis, we can assume r2 = 10mΩ. From the selected parameter values, jX2 = -100jmΩ and jωM = 50jmΩ. If the quality factor of the isolated loop 2 is, for example, 500, the reactance of the untuned loop is 5jΩ. Therefore, the required mutual reactance is small compared to the reactance of the untuned loop. In order to achieve such a relatively small coupling between two similarly sized loops, an impractically large spatial separation is usually involved, which is incompatible with the requirements of compactness. The passive reflector is inserted between loop 1 and loop 2. It is not a resonant structure and cannot significantly change the phase of the scattered near field. Instead, it is used to partially shield the field generated by one loop from affecting the other loop by supporting eddy currents on the reflector surface. This optimizes the value of M between loop 1 and loop 2 and allows the development of a compact spatial arrangement of the loops.

[0172] Another effect of the passive reflector is to increase the ratio α=ε2 / ε1 (thereby reducing β). The reduction of β is beneficial from the point of view of further reducing the reflection impedance that appears in loop 1 due to the proximity of loop 2 (as shown in equation 5). This achieves more effective magnetic resonance signal coupling with loop 1.

[0173] Example 3 - Passive Insert Functionality

[0174] Inserts, such as the passive insert 306 described in relation to the above embodiments, can be used for a variety of purposes. For example, the insert will reduce the RF field strength near the main loop. This has the effect of reducing eddy currents in the ore very close to the loop, and therefore also reducing the reflected resistance in the main loop. This has the advantage that significantly increased current can be driven in the main loop at the same available power level. Figures 8 and 9 show in contour plot form the RF field strength near the main loop without the insert ( Figure 8a and Figure 8b ) and with insert ( Figure 9a and Figure 9b ) is compared with the calculated field strength per unit current of the main circuit. Figure 9b The insert is an oblate spheroid placed in the plane of the main loop (see Figure 9a Main circuit cross section shown in ). Figure 9b The contours very close to the loop in the graph show a significant reduction in field strength. On the other hand, the field strength at a large distance from the loop is only slightly affected by the insert. Depending on the severity of the eddy current losses, the increase in current due to the reduction in the main loop resistance can lead to an overall sensitivity advantage at greater distances from the sensor.

[0175] The insert also reduces the sensitivity of the primary loop very close to the sensor compared to further away from the sensor, thereby "flattening" the sensor response with respect to depth. This has the benefit of providing more uniform sensing within the rock half-space. Fig.10 A comparison plot between the normalized field (on axis) due to the main loop only (blue trace) and the loop plus insert (black trace) is shown. The red trace is the field generated by eddy currents on the insert surface, which acts to cancel the field very close to the main field. The RF field very close to the main loop is preferentially reduced compared to the field far from the main loop. Because the sensitivity depends on the normalized RF field, an improvement in sensing uniformity is achieved.

[0176] Example 4 - Obtaining Uniform Spatial Sensitivity

[0177] Most sensing technologies, when applied to single-sided measurement applications, are limited by the fact that the sensing field or flux decays with distance from the sensor, and where the measurement response similarly decreases rapidly with distance from the sensor location, typically at a rate of at least "1 / r". 2 ” approach. Although the electromagnetic field from the loop also typically decays monotonically away from the loop aperture, the MR response curve can be made to peak at some distance away from the sensor. This is because the MR resonance response is nonlinear in the applied excitation field. There are a variety of MR phenomena that can be used for analysis, including saturation, internal destructive interference, and variable magnetization rotation.

[0178] Experiments have been conducted to demonstrate the sensitivity analysis approach. Fig.11 An MR sensor suspended above a half-space is shown, wherein a sample comprising a thin disk may be located at different displacements from the sensor in a plane parallel to the sensor face. The disk is used to simulate a thin mineralized layer in the half-space below the sensor. For different MR pulse sequences and signal analysis methods (masking), the spacing of the disk from the sensor is different to characterize the sensor response with respect to the mineral depth. For each type of sequence and signal analysis method, a different relationship between sensitivity and sample depth can be obtained. These relationships are referred to herein as "sensitivity profiles". The above experiments represent a calibration procedure in which various sensitivity profiles are generated before being used for ore half-space measurements.

[0179] Figures 12a to 12c Three different sensitivity distributions obtained for three different pulse sequences and analysis methods (masking) are shown. Distribution A ( Fig.12a ) is generated by analyzing the MR signal power early during the free induction decay (FID) produced by a specific pulse sequence (in this case a single long pulse). Distribution B( Figure 12b ) is generated by the analysis of the same type of FID at a later time period.

[0180] Fig.13a and Fig.13b A masking method for generating a sensitivity distribution is shown. Masking has been applied to specific time domains of the signal to extract specific portions of the signal power occurring during those time periods. In this example, masking is used to extract the specific portions of the signal power in the FID waveform corresponding to the earlier analysis ( Fig.13a ) and post-analysis ( Fig.13b ) at different times. Distribution C( Fig.12c ) is generated by analysis of the magnetic resonance response resulting from a shorter pulse length. Many different sensitivity profiles can be formed in actual ore measurements, because the MR measurement parameters can be dynamically changed in real time to alternately generate a specific sensitivity profile during normal operation.

[0181] Note that a relatively constant sensitivity with depth is obtained by simply using pulse and analysis parameters corresponding to profile A. This indicates that for this configuration the MR measurement is not “flooded” by grades close to the surface, i.e. the measurement is not significantly biased based on the upper zone grade.

[0182] Figures 12a to 12c The sensitivity distributions in also allow for the formation of a composite sensitivity distribution of a desired shape by linear combinations of the available sensitivity distributions. In general, the sensitivity distributions form a "basis set"; each sensitivity distribution can be summed in a weighted linear combination to reproduce a new sensitivity distribution designed to significantly overlap a specified measurement zone.

[0183] The weighting process is performed as follows. Each MR measurement configuration provides a single waveform for the entire half-space below the sensor. The waveform for each configuration is analyzed using signal masking to extract one or more sensitivity distribution "weights". For example, for the long pulse configuration, the early and late signal powers are analyzed to provide two values ​​(S and A and S B ), which estimate the weight of each sensitivity distribution mode in the half space. In the example discussed here, the third sensitivity distribution intensity S C Also derived from the second MR measurement configuration (short pulse configuration). Each sensitivity distribution weight is normalized to a known calibration weight corresponding to a uniform ore grade of a determined value. Thus, the sensitivity distribution intensities carry information about the distribution and the quantitative grade value.

[0184] Once the sensitivity distribution weights are determined, they can be used to weight the corresponding sensitivity distributions to estimate the shape of the grade distribution for a given zone in the half-space. Multiple sensitivity distributions can be used to optimize a flat response with respect to depth, or alternatively, a combination of sensitivity distributions can be set that are weighted preferentially in specific zones. The latter approach allows grade to be analyzed with depth.

[0185] Those skilled in the art will appreciate that numerous variations and / or modifications may be made to the above-described embodiments without departing from the broad general scope of the present disclosure. Therefore, the embodiments of the present invention are to be considered in all aspects as illustrative and not restrictive.

Claims

1. A device for measuring ore in a mining transport vehicle, the device comprising: a gate defining a gate area in which a transport vehicle carrying ore can be located or can move through the gate area, at least one magnetic resonance (MR) sensor included in the gate, the MR sensor comprising: a main circuit, the main circuit being positionable in the gate area above the charge of ore carried by the transport vehicle, a drive loop located above the main loop and electrically isolated from and magnetically coupled to the main loop, wherein a radio frequency (RF) transmitter can be coupled to a feed terminal of the drive loop to drive a radio frequency drive current in the drive loop, and a radio frequency receiver can be coupled to the drive loop to monitor a radio frequency response current in the drive loop; The device also includes: A magnetic resonance sensor control system configured to control at least one of: the positioning of the at least one magnetic resonance sensor relative to the gate area and / or ore batch; the positioning of elements included in the at least one magnetic resonance sensor relative to each other; electromagnetic suppression properties of the at least one magnetic resonance sensor; and / or The sensitivity of the at least one magnetic resonance sensor varies with the distance of the at least one magnetic resonance sensor from the ore batch.

2. The apparatus of claim 1, wherein the primary loop comprises a plurality of conductive segments and capacitors located between the conductive segments.

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

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

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

6. The apparatus of claim 5, comprising an impedance monitor for monitoring a reactive impedance at the feed terminals of the drive loop, and wherein the magnetic resonance sensor control system adjusts the capacitance based on the monitored reactive impedance.

7. The apparatus of claim 6, wherein the magnetic resonance sensor control system is configured to adjust the capacitance so that the reactive impedance at the feed terminal of the drive loop is at a target reactive impedance.

8. The apparatus of claim 2 or 3, wherein the conductive segments and capacitors of the primary loop extend along an annular path, and in a cross section in a plane perpendicular to the annular path, the conductive segments have a non-circular cross-sectional shape.

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

10. The apparatus of claim 9, wherein the convex boundary is radially outside the primary loop and the concave boundary is radially inside the primary loop.

11. The apparatus of claim 8, wherein the non-circular cross-sectional shape is a crescent shape or a kidney shape.

12. The device of claim 11, wherein the crescent shape is formed by two intersecting ovals.

13. The apparatus of any of the preceding claims 1-3, wherein the magnetic resonance sensor control system is configured to adjust: the position and / or orientation of the at least one magnetic resonance sensor relative to the ore charge; and / or The position and / or orientation of the drive circuit relative to the main circuit.

14. The apparatus of claim 13, comprising an impedance monitor for monitoring the resistive impedance at the feed terminals of the drive loop, and wherein the magnetic resonance sensor control system makes the following adjustments: adjusting the position and / or orientation of the at least one magnetic resonance sensor relative to the ore charge based on the monitored electrical impedance; and / or The position and / or orientation of the drive loop relative to the main loop is adjusted based on the monitored resistive impedance.

15. The apparatus of claim 14, wherein the magnetic resonance sensor control system adjusts the position and / or orientation so that the resistive impedance at the feed terminals of the drive loop is at a target resistive impedance.

16. An apparatus as claimed in claim 15, wherein the magnetic resonance sensor control system adjusts the position and / or orientation of the at least one magnetic resonance sensor relative to the ore batch so that the resistance impedance at the feed terminal of the drive circuit is within a predetermined resistance impedance range, and then adjusts the position and / or orientation of the drive circuit relative to the main circuit so that the resistance impedance at the feed terminal of the drive circuit is at the target resistance impedance.

17. The apparatus of claim 12, comprising a displacement monitor for monitoring displacement between the at least one magnetic resonance sensor and the charge of ore.

18. The apparatus of claim 17, wherein the magnetic resonance sensor control system adjusts the position and / or orientation based on the monitored displacement.

19. Apparatus as claimed in claim 18 wherein the magnetic resonance sensor control system adjusts the position and / or orientation based on the monitored displacement to maintain a fixed spacing between the charge of ore and the main circuit.

20. Apparatus as claimed in any one of claims 1 to 3, comprising a reflector located above the primary loop, the reflector being arranged to reduce radiation and magnetic near fields from the ore charge in an upward direction.

21. The device of any of the preceding 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.

22. The apparatus of claim 20, comprising a passive loop located above or in the plane of the primary loop, wherein the reflector is located between the primary loop and the passive loop.

23. The apparatus of claim 21, wherein the passive loop has a capacitive lumped impedance that is adjustable by the magnetic resonance sensor control system to optimize rejection of external electromagnetic interference in the primary loop.

24. The apparatus of any preceding claim 1-3, comprising a noise monitor for monitoring radio frequency noise voltage at the feed terminals of the drive loop.

25. The apparatus of claim 24, comprising a passive loop located above or in the plane of the main loop, wherein the magnetic resonance sensor control system is configured to adjust a capacitive lumped impedance of the passive loop based on the monitored RF noise voltage to minimize the RF noise voltage at the feed terminal of the drive loop.

26. The device of any of the preceding claims 1-3, comprising a resistive loop magnetically coupled to the primary loop and resistively terminated.

27. The apparatus of claim 26, wherein the magnetic resonance sensor control system is configured to adjust the orientation of the resistive loop relative to the main loop.

28. The apparatus of claim 27, comprising an impedance monitor for monitoring a resistive impedance at the feed terminals of the drive loop, and wherein the magnetic resonance sensor control system is configured to adjust the orientation of the resistive loop relative to the main loop based on the monitored resistive impedance so that the resistive impedance at the feed terminals of the drive loop is at a target resistive impedance.

29. The device of any of the preceding claims 1 to 3, comprising an insert located radially inside the primary circuit in the plane of the primary circuit.

30. The apparatus of claim 29, wherein the insert is an oblate spheroid.

31. Apparatus as claimed in any one of the preceding claims 1 to 3, wherein the transport vehicle is a truck, a load-haul-dump (LHD) vehicle, a dump truck, a van or a trolley.

32. The apparatus of any preceding claim 1-3, comprising a gate control system.

33. The apparatus of claim 32, wherein the gate control system is configured to control movement of the transport vehicle through the gate zone of the gate.

34. The apparatus of claim 33, wherein the gate control system is configured to control the transfer of information between the apparatus and one or more other components of a mining environment.

35. Apparatus as claimed in any one of claims 1 to 3, wherein in order to control the sensitivity of the at least one magnetic resonance sensor in dependence on the distance of the at least one magnetic resonance sensor from the ore charge, the magnetic resonance sensor control system is configured to: controlling the application of at least one radio frequency pulse sequence to the at least one magnetic resonance sensor and analyzing a magnetic resonance response signal from the ore charge using at least one corresponding analysis method, wherein the at least one radio frequency pulse sequence and its corresponding analysis method have corresponding predetermined sensitivity distributions, using analysis of the magnetic resonance response signal to measure a corresponding sensitivity distribution weight; and The sensitivity distribution weights are used to estimate the concentration of minerals in the ore batch as a function of depth.

36. Apparatus as claimed in any one of claims 1 to 3, wherein in order to control the sensitivity of the at least one magnetic resonance sensor in dependence on the distance of the at least one magnetic resonance sensor from the ore charge, the magnetic resonance sensor control system is arranged to: controlling application of a first radio frequency pulse sequence to the magnetic resonance sensor and analyzing a first magnetic resonance response signal from the ore charge using a corresponding first analysis method, wherein the first radio frequency pulse sequence and the corresponding first analysis method have corresponding first predetermined sensitivity distributions, controlling the application of one or more further radio frequency pulse sequences to the magnetic resonance sensor and analysing one or more further magnetic resonance response signals from the ore charge using one or more corresponding further analysis methods, wherein the one or more further radio frequency pulse sequences and the one or more corresponding further analysis methods each have a corresponding further predetermined sensitivity profile, using said analysis of said first and further magnetic resonance response signals to measure corresponding first and further sensitivity distribution weightings; summing the first sensitivity distribution weight with the further sensitivity distribution weight to produce a spatial sensitivity distribution weight; and The sensitivity distribution weights are used to estimate the concentration of minerals in the ore batch as a function of depth.

37. A method of measuring ore in a mining haulage vehicle using the apparatus of any preceding claim.

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