Measuring equipment for measuring moisture of mineral material

Abstract

A measurement device for measuring moisture of a mineral material, comprising a resonator, the relative permittivity of a solid material structure of the resonator being configured to be higher than the relative permittivity of a cavity having a mineral material; the resonator comprising a probe arrangement within the solid material structure, the probe arrangement being configured to cause an electromagnetic resonance of the resonator within the cavity in response to electrical energy fed to the resonator by the probe arrangement; the solid material structure of the resonator and the cavity are configured to cause a non-uniform distribution of a resonant magnetic field between the cavity and the solid material structure such that the magnetic field is cancelled in the cavity due to the relative permittivity of the solid material structure being higher than the cavity; the cavity is configured to contain mineral material for moisture measurement; the probe device is configured to output a frequency response of the resonator affected by the mineral material for determining a moisture content of the mineral material.

Description

Technical Field

[0001] The utility model relates to a measuring device and a measuring method for measuring the moisture content of mineral materials. Background Art

[0002] Moisture measurements in non-magnetic mineral materials are usually performed using radio frequency electromagnetic radiation. One disadvantage of this method is that the measurement of the moisture percentage of the material depends on the magnetic properties of the material. However, the relative magnetic permeability and magnetic losses of magnetite, for example, are high and vary. Therefore, when radio frequency electromagnetic radiation is transmitted through such a mineral sample, the moisture measurement is not reliable due to the random variations in magnetic permeability and magnetic losses. In addition, the moisture measurement is sensitive to the material density, which may also vary randomly. The literature Study of the Magnetite to maghemite transition using microwave permittivity and permeability (J. A. Cuenca et al., February 16, 2016) introduces microwave cavity interferometry measurements.

[0003] These problems have been recognized, but no useful solution exists for correctly measuring moisture. Attempts have been made to overcome this problem by using reflectance measurement instead. Reflectance measurement is inaccurate because it is sensitive to surface roughness, slope, ambient reflection, and material density, is affected by material permeability, and is not representative (it only measures surface moisture). Therefore, improvements would be welcome. Utility Model Content

[0004] The present invention seeks to provide improvements in measurement.

[0005] The utility model provides a measuring device for measuring the moisture content of a mineral material. The measuring device comprises a resonator, wherein a relative permittivity of a solid material structure of the resonator is configured to be higher than a relative permittivity of a cavity having the mineral material; the resonator comprises a probe device in the solid material structure, the probe device being configured to cause electromagnetic resonance of the resonator in the cavity in response to electric energy fed to the resonator through the probe device; the solid material structure of the resonator and the cavity are configured to cause an uneven distribution of a resonant magnetic field between the cavity and the solid material structure, so that the magnetic field is offset in the cavity because the relative permittivity of the solid material structure is higher than that of the cavity; the cavity is configured to contain a mineral material for moisture measurement; and the probe device is configured to output a frequency response of the resonator affected by the mineral material, so as to determine the moisture content of the mineral material.

[0006] Advantageously, the solid material structure of the resonator comprises zirconium oxide ZrO2.

[0007] Advantageously, the relative permittivity of the solid material structure is in the range of 20-100.

[0008] Advantageously, the measuring device comprises a data processing unit configured to determine a density-compensated moisture content of the mineral material based on a frequency response of the resonator as affected by the mineral material.

[0009] Advantageously, the data processing unit is configured to determine the density compensated moisture content of the mineral material based on at least two of the following frequency responses: a resonant frequency of the resonator, a Q value of the resonance and a signal level of the resonance.

[0010] Advantageously, the data processing unit comprises one or more processors; and one or more memories comprising computer program code; the one or more memories and the computer program code being configured to, together with the one or more processors, cause the data processing unit to determine the moisture content of the mineral material based at least on a frequency response of the resonator affected by the mineral material.

[0011] Advantageously, the measuring device comprises two sample feed systems, a first sample feed system being configured to feed mineral material at a first volume flow rate towards a second sample feed system, and the second sample feed system being configured to feed mineral material to and through the cavity of the resonator at a second volume flow rate, the second volume flow rate being greater than the first volume flow rate.

[0012] Advantageously, the measuring device is configured to measure mineral material comprising ferromagnetic and / or ferrimagnetic material.

[0013] Advantageously, the measuring device is configured to measure mineral material comprising magnetite and / or hematite.

[0014] Advantageously, the probe device comprises a first coupling probe and a second coupling probe, wherein an angle α between a radial line from the second coupling probe to the longitudinal axis of the resonator and a radial line from the first coupling probe to the longitudinal axis of the resonator is π / 2, and a length of a radial line from the second coupling probe to the longitudinal axis of the resonator is d.

[0015] Advantageously, the probe arrangement comprises a pair of feeding probes at positions (l, β), wherein l is the radial distance from the longitudinal axis of the resonator for the pair of feeding probes, the angle β between the pair of feeding probes is π, and the measuring device is configured to feed the pair of feeding probes with signals having the same phase to both of them so as to eliminate interfering resonances having frequencies different from the measured resonance frequency.

[0016] Advantageously, the solid material structure is a plate having a hole therethrough, the hole being located on the inner side of the periphery and the hole comprising a cavity; the measuring device comprising a conduit connected to the hole, the conduit being configured to allow mineral material to flow through the measuring device; the measuring device comprising a layer of conductive material located on the plate of the solid material structure and on the conduit. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Exemplary embodiments of the present invention are described below by way of example only and with reference to the accompanying drawings, in which

[0018] Figure 1 An example of a measuring device is shown;

[0019] Figure 2 An example of a solid material structure with a probe arrangement is shown;

[0020] Figure 3 An example of a feed system is shown;

[0021] Figure 4 An example of probe location is shown;

[0022] Figure 5 An example of a feed probe is shown;

[0023] Figure 6 An example of another resonator is shown;

[0024] Figure 7 An example of the frequency response of a resonator is shown;

[0025] Figure 8 An example of a data processing unit is shown;

[0026] Fig. 9 An example of tilt interference resonance is shown; and

[0027] Fig.10 An example of a flow chart of a measuring method is shown. DETAILED DESCRIPTION

[0028] The following embodiments are merely examples. Although the specification may refer to "one" embodiment in several places, this does not necessarily mean that each such reference refers to the same embodiment, or that the feature applies to only a single embodiment.

[0029] In this document, the articles "a" and "an" give the general meaning of entity, structure, component, composition, operation, function, connection, etc. It is also noted that singular terms may include plural terms.

[0030] Individual features of different embodiments may also be combined to provide other embodiments. Furthermore, the words "comprising" and "including" should be understood as not limiting the described embodiments to consist only of those features that have been mentioned, and such embodiments may also include features / structures that are not specifically mentioned. All combinations of embodiments are considered possible if the combination of embodiments does not result in structural or logical contradictions.

[0031] The term "about" indicates that the quantity or any value is not exact, and usually does not need to be exact. The reasons may be tolerance, resolution, measurement error, rounding, etc., or it may be that the characteristics of the solution herein only require the quantity or value to be approximately that large. A certain tolerance is always included in quantities and values ​​in real life.

[0032] It should be noted that although the drawings show various embodiments, they are simplified diagrams showing only some structural and / or functional entities. The connections shown in the drawings may refer to one or more similar or different connections. It is obvious to those skilled in the art that the described devices may also include other functions and structures in addition to the functions and structures described in the drawings and text. It should be understood that some of the details of the functions, structures and signaling for measurement and / or control are irrelevant to the actual utility model. Therefore, there is no need to discuss them in more detail here.

[0033] Magnetite materials such as magnetite concentrate and magnetite ore have proven difficult for prior art measurements based on conventional microwave transmission techniques. The reason for the difficulty is believed to be the magnetic properties or the varying magnetic permeability of the magnetite materials. Magnetic permeability is the degree to which a material is magnetized to a magnetic field.

[0034] It is also believed that microwave or RF transmission signals are greatly affected by the water within the ore or magnetite material and the magnetic permeability of the ore or magnetite material. This is a problem because changes in moisture cannot be distinguished from changes in magnetic permeability.

[0035] It is well known that in microwave transmission, the electric field and the magnetic field are in phase. This means that the electromagnetic properties of the material have the same effect on the traveling wave. In a resonator, the situation is different. In RF and microwave cavity resonators, the phase difference between the electric field and the magnetic field is π / 2. This means that where the electric field is maximum, the magnetic field is minimum. From this, it can be inferred that if the sample of the material being measured is located in a place inside the resonator where the electric field is strong and the magnetic field is weak, the moisture content of the sample can be measured with the electric field, so that the moisture result is completely independent of the magnetic properties of the sample material, or this dependence is limited and acceptable, which enables reliable moisture measurements.

[0036] The relative density of magnetite is about 5, which means that a certain volume of magnetite weighs about 5 times as much as the same volume of water (which has a relative density of 1). The moisture content of magnetite material, as an example of a mineral material, is typically about 0% to about 10% by weight in many processes, which means about 0% to about 35% by volume. The term mineral material refers to either a concentrate, which is the valuable part of the mineral material, or a mineral tailing, which is the worthless part of the mineral material. Mineral tailings may also be referred to as tailings or waste streams. Any magnetic material can be measured, since such materials are based on mineral materials.

[0037] In the prior art, microwave resonator measurements are usually used when the water content is below 30% by volume. This means that special resonator devices are required for measuring mineral materials. In order to perform the measurement, in the measurement volume the magnetic field should be canceled or minimized. At the same time, it is beneficial if the electric field strength in the measurement volume is reduced and the measured volume inside the resonator is relatively small compared to the total volume of the resonator structure. In this way, the measurement is suitable for high water contents and also for other mineral materials that are denser than magnetite.

[0038] It is well known that the electrical properties of magnetic materials can be measured by using a TM resonator with zero magnetic field in the middle. 010The method uses a circular waveguide resonator with a 2.4-kV mode to measure the magnetic field. The disadvantage of this method is that the volume where the magnetic field is zero is very small and cannot be used to measure the large volumes of material required for industrial measurements. Such measurements are presented in Study of the Magnetite to maghemite transition using microwave permittivity and permeability measurements (Jerome Alexander Cuenca, Keith Bugler, Stuart Taylor, David Morgan, Paul Williams, Johann Bauer and Adrian Porch, Journal of Physics: Condensed Matter, Volume 28, Issue 10, February 16, 2016).

[0039] The solution to this problem is to enlarge the volume of zero magnetic field by partially filling the resonator with a high permittivity material. This approach has two effects: first, the electric field strength is higher in the high permittivity part and lower in the center of the resonator where the measured material is located; second, the volume of zero magnetic field is increased. Here, zero value means that the value is zero or at least approximately zero. A value at least approximately zero means a value that corresponds to zero within the tolerance or resolution of the measurement, i.e. it does not significantly interfere with the measurement, but reliable results can be obtained from the measurement.

[0040] Figure 1 An example of a measuring device for measuring the moisture content of a mineral material is shown viewed from the side such that the longitudinal axis LA of the pipe 104 extends from left to right. Figure 2 An example of a measuring device is shown as seen in the direction of the longitudinal axis LA of the pipe 104. The measuring device comprises a resonator 100. The resonator 100 is located around the pipe 104. The cross section of the resonator 100 is bounded by and contains the area of ​​the solid material structure 114 located between the inner periphery 110 and the outer periphery 112. Alternatively, the resonator 100 may have two parts facing each other on opposite sides of the pipe 104 (as they are in FIG. Figure 1 See also Figure 6 ).

[0041] There is a distance between the inner periphery 110 and the outer periphery 112, which is filled with solid material. The cavity 106 of the measuring device is located within the inner periphery 110, and includes a volume where the interaction between the electromagnetic radiation and the mineral material sample occurs.

[0042] The relative permittivity of the solid material structure 114 of the resonator 100 between the inner periphery 110 and the outer periphery 112 is higher than the relative permittivity of the cavity 106 having the mineral material. Typically, the relative permittivity range of the mineral material is known in advance based on various mineral chemical analyses. Therefore, it is easy to select the solid material for the resonator 100. On the other hand, if an estimated value of the relative permittivity of the mineral material is not known, the relative permittivity of the solid material structure 114 can be selected to be as high as possible. A test run can then be performed. In one embodiment, the solid material of the solid material structure 114 may include zirconium oxide ZrO2. When measured using a frequency of about 2.5 GHz, the relative permittivity of zirconium oxide is about 30, while the relative permittivity of magnetite is about 5.2.

[0043] The resonator 100 includes a probe device 108 within the solid material structure 114, which is configured to induce electromagnetic resonance of the resonator 100 within the cavity 106 in response to electrical energy fed to the resonator 100 through the probe device 108. Figure 2 In the embodiment, for example, the probe can be a coaxial probe. Each probe 300, 302, 304, 310, 312 (see Figure 4 , 5 ) can be considered to include an electrical conductor, which is inserted into or on the solid material structure 114. The resonator 100 can generally be excited by a variety of methods, such as through a ring or a hole, which is known to those skilled in the art. Because the solid material partially fills the waveguide or resonant cavity of the resonator 100, the probe and external circuitry such as the data processing unit 120 are coupled together so that electrical energy can be fed to the resonator 100 and the frequency response of the resonator 100 can be measured.

[0044] The solid material structure 114 and cavity 106 of resonator 100 are configured to cause an uneven distribution of the resonant magnetic field of the electromagnetic field between cavity 106 and solid material structure 114. As a result, cavity 106 has a lower permittivity than the solid material structure 114 of resonator 100. The solid material structure 114 has a higher permittivity than cavity 106. The magnetic field is canceled in cavity 106. The magnetic field has a zero magnetic field in the middle of cavity 106, and the high permittivity of material 114 increases the effective size of the resonator and makes the zero magnetic field volume larger. Therefore, these differences in relative permittivity cause the magnetic field to be mainly located in the solid material structure 114 of resonator 100, and relatively less inclined to reside in cavity 106. Most of cavity 106 is typically air, while solid material structure 114 has mainly materials with high relative permittivity. The walls of cavity 106 are made of solid materials with low relative permittivity. For example, the relative permittivity of the walls of cavity 106 can range from 2 to 10. Permittivity is the ability of a material to allow a magnetic field to pass through it.

[0045] The electric field generally has a maximum value at the center of the resonator. However, by appropriately placing a higher permittivity material outside the center of the resonator, the electric field will partially shift in the direction of the higher permittivity, so the electric field is weakened in the volume at and near the center of the resonator. Based on this, the moisture percentage of various materials can be measured by placing them in a low electric field at the center of the resonator 100, including those materials that are normally difficult to measure.

[0046] Therefore, the measurement of the moisture content of the mineral material within the cavity 114 is mainly based on the electric field to avoid problems related to the magnetic properties of the mineral material.

[0047] During the moisture measurement, the cavity 106 contains the mineral material. The measurement of the mineral material can be a batch process or a continuous flow process. In a batch process, the cavity 106 can act as a measurement chamber, and the measurement step can include filling the measurement chamber completely or partially with the mineral material, performing the measurement, and emptying the measurement chamber. A new measurement can then be performed starting from the filling of the measurement chamber.

[0048] In a continuous flow measurement, the mineral material flows continuously through the chamber 106 and measurements are performed continuously or repeatedly. The repeated measurements may be performed periodically or aperiodically.

[0049] Figure 3 An example of an embodiment is shown, in which the measuring device comprises two sample feed systems 200, 202. The first sample feed system 200 feeds mineral material towards the second sample feed system 202 at a first volume flow rate, and the second sample feed system 202 feeds mineral material to and through the cavity 106 of the resonator 100 at a second volume flow rate. The volume flow rate defines the volume of mineral material passing through the cavity 106 per unit time. The second volume flow rate may be greater than the first volume flow rate. The difference in volume flow rate (i.e. flow rate) results in an increased amount of mineral material per unit time relative to the amount of mineral material of the first feed system 200.

[0050] The volumetric flow rate can also be kept constant if the volume of feed system 202 is greater than the volume of feed system 200. In this way, the moving parts of feed systems 200, 202 can be the same, but the internal volume of the stationary parts (i.e., the diameter or square root of the cross-sectional area of ​​conduit 104) can be different, such that the diameter or square root of the cross-sectional area is greater inside resonator 100 than outside resonator 100. However, both the volumetric flow rate and the diameter or square root of the cross-sectional area can be greater inside resonator 100 than outside resonator 100. Figure 3 It is shown that the cross-sectional area and volume flow rate of the conduit 104 are greater inside the resonator 100 than outside the resonator 100 .

[0051] When the cavity 106 is not filled with mineral material, the average relative permittivity of the cavity 106 remains lower than the average relative permittivity of the solid material structure 114. This feature enables the measurement of materials with high relative permittivity. That is, the permittivity of the mineral material alone may even be higher than the permittivity of the solid material structure 114, but the average value of the cavity 106 is still lower. This results in the magnetic field mainly residing in the solid material structure 114 and enabling the correct measurement of the moisture percentage of the mineral material. This also results in the electric field mainly residing in the cavity 106 to enable the correct measurement of the moisture percentage of the mineral material based on the electric field.

[0052] The first feed system 200 can be a screw feeder, an auger feeder, a conveyor belt, any combination thereof, etc. The second feed system 202 can be a screw feeder, an auger feeder, a conveyor belt, any combination thereof, etc. made of non-conductive material. In the case of a screw feeder, the first feed system 200 and the second feed system 202 can have a common shaft so that both rotate at the same speed. However, since the diameter of the second feed system 202 is larger than the diameter of the first feed system 200, the second feed system 202 has a larger volume flow rate than the first feed system 200. Another solution is that the first feed system 200 and the second feed system 202 have different rotation speeds.

[0053] The probe device 108 transmits or outputs information about the frequency response of the resonator 100. The frequency response may include a resonant frequency or a resonant frequency range. The resonant frequency range may include a full width at half maximum (FWHM) or a corresponding width (see Figure 7 ).

[0054] The frequency response can include the signal level at the resonant frequency or frequency range (see Figure 7 ). The level may refer to the amplitude or power of the signal. The level of the resonance caused by the mineral material may be measured relative to a measurement without the mineral material (i.e. without any sample). Alternatively or additionally, the reference may be a measurement of a known and / or predefined sample.

[0055] The frequency response may include the Q value of the resonance. The Q value refers to a quality factor that describes the degree of underdamping or damped oscillation in a resonator. The Q value itself is well known to those skilled in the art.

[0056] The determination of these parameters (resonance frequency, level, Q value) for the moisture content of the mineral material is affected by the moisture content of the mineral material in the cavity 106. A baseline can also be considered (see Figure 7). In one embodiment, by measuring two resonator parameters, a density compensation of the mineral material can be determined. That is, if the density of the mineral material changes, it will also affect the measurement, but the effect caused by the density change can be offset by the measurement of two parameters. Such a measurement result can be expressed by a pair of equations with two variables: density and moisture. Due to the pair of equations, both or one of the variables can be solved. If the density of the material being measured is at least approximately constant, then one parameter is sufficient and suitable for measuring the moisture content of the mineral material.

[0057] Density can also be compensated by measuring the weight of the mineral material being measured. The weight measurement can be continuous or sample by sample.

[0058] In one embodiment, the optimal operating frequency of the measurement device may be in the range of about 100 MHz to 1 GHz. At lower frequencies, interfering conductivity effects rise, while at higher frequencies, the resonator size may be impractically small.

[0059] In one embodiment, the relative permittivity of the solid material structure 114 may be in the range of 20 to 100. In this embodiment, the permittivity of the material under test is lower than the permittivity of the solid material structure 114 .

[0060] The measuring device may further comprise a data processing unit 120 which determines the moisture content of the mineral material based on the frequency response which may also comprise the signal level of the resonator 100 transmitted by the probe device 108. The data processing unit 120 may also feed electrical energy to the resonator 100 via the probe device 108. During the measurement of the mineral material, the cavity 106 contains the mineral material which affects the frequency response of the resonator 100.

[0061] exist Figure 8 In an embodiment of which an example is shown in , the data processing unit 120 may include one or more processors 700 and one or more memories 702, the memories 702 including computer program code. The one or more memories 702 and the computer program code are configured to, together with the one or more processors 700, cause the data processing unit to determine the moisture content of the mineral material based on at least the frequency response of the resonator 100 affected by the mineral material.

[0062] In one embodiment, the measuring device is configured to measure mineral materials comprising ferromagnetic and / or ferrimagnetic materials. Alternatively or additionally, measurements may also be performed when the material comprises paramagnetic and / or diamagnetic materials.

[0063] In one embodiment, the measuring device may measure mineral material comprising magnetite and / or hematite.

[0064] exist Figure 4In an embodiment of which an example is shown in FIG. 1 , the probe arrangement 108 may include a second coupling probe 302 located at a position d, α in a polar coordinate system, where d is a radial distance from the longitudinal axis LA of the resonant cavity 100, and the angle α between the first probe 300 and the second probe 302 is π / 2. The distance d of the probe 302 may be different from the distance of the probe 300.

[0065] exist Figure 5 In an embodiment of which an example is shown in FIG. 1 , the second feeding probe 310 can be fed in phase with the first feeding probe 312. In this way, the interfering resonance 402 can be eliminated because its electric field has an opposite electric field at the location of the feeding probes 310 and 312. Probe 304 is a receiving probe. The frequency of the resonance 402 is different from the measured resonance frequency 400 (see FIG. 1 ). Figure 7 ).

[0066] Figure 6 An example of a resonator having a column of solid material structure 114 having a material with a high relative permittivity on a pipe 104 through which mineral material flows is shown. In this example, the pipe 104 is not located in the middle of the hole of the column of solid material 114, but rather the columns of solid material 114 are located on opposite sides of the pipe 104. In this embodiment, also as in Figure 1 As in the embodiment shown, the electric and magnetic fields are strong within the solid material 114. From a practical point of view, the magnetic field within the pipe 104 is zero, thereby also enabling the measurement of magnetic materials. The electric field within the pipe 104 is weaker than within the solid material 114.

[0067] Figure 7 An example of a frequency response of a resonator 100 is shown. Curve 404 shows an example of a measurement of an empty resonator 100 (i.e. without mineral material). The probe arrangement 108 comprises probes located on opposite sides of the longitudinal axis LA of the resonator 100. The probes of the probe arrangement 108 may be, for example, monopoles, loops or holes, but are not limited thereto. In addition to the measurement resonance 404 of the resonator 100, an interfering resonance 402 can be clearly seen. The measurement resonance in this example is TM 010 The interfering resonance in this example is TM 210 In this example Figure 7 The third resonance on the right is TM 410 Curve 406 represents the measured values ​​for a mineral material. Here again the measured resonance 400 can be seen, but also the interfering resonance 402 is present.

[0068] exist Figure 5In an embodiment in which an example is shown, the probe device 108 may include a pair of feeding probes 310, 312 located at positions l, β in a polar coordinate system, where l is a radial distance separated from the longitudinal axis LA of the resonator 100, and an angle β between the pair of feeding probes 310, 312 is π. The measurement device is configured to feed the pair of feeding probes 310, 312 with signals having the same phase for them so as to eliminate interfering resonances 402 having a frequency different from the measured resonance frequency 400. The probe 304 is a receiving probe. Figure 7 Curve 408 in FIG. 4 shows an example of the frequency response of a wet material of this embodiment, and the interfering resonance 402 has almost disappeared and the Q value of the resonant frequency 400 can be measured.

[0069] It should also be noted that the influence of the interfering resonance 402 can alternatively or additionally be eliminated or reduced by the two sample feeding systems 200, 202. The difference in volume flow rate (i.e., flow velocity) results in a reduction in the amount of mineral material per unit time in the cavity 106 relative to the corresponding volume fed by the first feeding system 200. When the cavity 106 is not filled with mineral material, the average relative permittivity of the cavity 106 remains lower than the average relative permittivity of the solid material structure 114, even if the relative permittivity of the mineral material alone is higher than the relative permittivity of the solid material structure 114. This feature enables the measurement of materials with high relative permittivity and reduces the influence of the interfering resonance 402. Alternatively, the probe 304 can be a feeding probe, and the reception is performed by the probes 310 and 312.

[0070] exist Figures 1 to 5 In the embodiment shown, the solid material structure 114 can be a plate with a hole 105 passing through the plate. The hole 105 is located inside the periphery 112 and the hole 105 includes a cavity 106. The measurement device can then include a pipe 104 attached to the hole 105. The pipe 104 can extend through the hole 105. In this embodiment, the surface of the cavity 106 is the surface of the pipe 104. Alternatively, the pipe 104 can include two parts. One end of one part of the pipe 104 can be concentrically and possibly coaxially fixed to one side of the hole 105, and one end of the other part of the pipe 104 can be concentrically and possibly coaxially fixed to the other side of the hole 105. In this embodiment, the surface of the cavity 106 is the surface of the solid material structure 114.

[0071] The conduit 104 may allow the mineral material to flow through the measurement device and through the cavity 106 .

[0072] exist Figure 3 In an embodiment, one example of which is shown in , the measurement device may include a conductive material layer 124 on the solid material structure 114 and the pipe 104 for protecting the measurement from interfering electromagnetic radiation from the environment and / or preventing radiation leakage outward from the resonator 100.

[0073] Fig. 9 An example of a rotating electric field 800 that may occur in cavity 106 is shown. In this case, resonator 100 is fed by probe 312 and received by probe 302 at the location where the resonant minimum electric field 402 is located (the location of the resonant minimum electric field can be easily determined theoretically based on simulations and / or based on testing by those skilled in the art). Rotating electric field 800 may cause Figure 7 Such an interfering resonance 402 may be avoided or reduced by a pair of feeding probes 310, 312 being fed with a signal having the same phase for both of them.

[0074] This structure of the measuring device solves the measurement problems associated with magnetite and high-density non-magnetic materials. Explained in a simplified manner, the magnetic field is zero or close to zero in the wide volume inside the resonator. That is, the magnetic field strength in the cavity 106 is low. The electric field strength is zero or approximately zero outside the solid material structure 114. The effective measurement volume (i.e., the size of the cavity 106) is smaller than the total effective volume of the entire resonator structure, which includes the solid material structure 114 and the cavity 106. The physical diameter of the measuring device can be, for example, about 200 mm, and the effective diameter can be, for example, about 1 m. This size also allows representative measurements to be performed in industrial applications.

[0075] In one embodiment, at least a portion of the particles measured by the measuring device may be larger than about 0.1 mm and smaller than about 5 mm. In one embodiment, at least a portion of the particles measured by the measuring device may be larger than about 1 mm and smaller than about 5 mm. In one embodiment, at least a portion of the particles measured by the measuring device may be larger than about 2 mm and smaller than about 5 mm. In one embodiment, the flow rate of mineral material through the resonator 100 of the measuring device may be from about 10 kg to about 50 kg per minute.

[0076] Fig.10 9 is a flow chart of a measurement method. In step 900, electrical energy is fed to the resonator 100 of the measurement device through the probe device 108, the probe device 108 is located in the solid material structure 114 and causes electromagnetic resonance in the cavity 106 of the resonator 100 in response to the electrical energy, the cavity 106 of the measurement device is confined by the solid material structure 114, and the relative permittivity of the solid material structure 114 of the resonator 100 is higher than the relative permittivity of the mineral material being measured.

[0077] In step 902, the solid material structure 114 and the cavity 106 of the resonator 100 result in an uneven resonant magnetic field distribution between the cavity 106 and the solid material structure 114, and the magnetic field in the cavity 106 is offset, resulting in a distribution in which the magnetic field is mainly located in the solid material structure 114 of the resonator 100 and less in the cavity 106.

[0078] In step 904, the probe device 108 outputs a frequency response of the resonator 100 affected by the mineral material in the cavity 106 for determining the moisture content of the mineral material.

[0079] In optional step 906, the density-compensated moisture content of the mineral material is determined based on at least two of the following frequency responses: the resonant frequency of the resonator 100, the Q value of the resonance, and the resonant signal.

[0080] Fig.10 The method shown can be implemented as a logic circuit solution or a computer program. The computer program can be placed on a computer program distribution device for its distribution. The computer program distribution device can be read by a data processing device and it encodes computer program commands, performs measurements and optionally controls the process based on the measurement results.

[0081] The computer program may be distributed using a distribution medium that may be any medium readable by a controller. The medium may be a program storage medium, a memory, a software distribution package, or a compressed software package. In some cases, the distribution may be performed using at least one of: a near field communication signal, a short range signal, and a telecommunications signal.

[0082] It is obvious to a person skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. The present invention and its embodiments are not limited to the exemplary embodiments described above, but may vary within the scope of the claims.

Claims

1. A measuring device for measuring the moisture content of a mineral material, the measuring device comprising a resonator (100), characterized in that The relative permittivity of the solid material structure (114) of the resonator (100) is configured to be higher than the relative permittivity of the cavity (106) having the mineral material; The resonator (100) includes a probe device (108) within the solid material structure (114), the probe device being configured to cause electromagnetic resonance of the resonator (100) within the cavity (106) in response to electrical energy fed to the resonator (100) through the probe device (108); The solid material structure (114) of the resonator (100) and the cavity (106) are configured to cause an uneven distribution of the resonant magnetic field between the cavity (106) and the solid material structure (114), so that the magnetic field is cancelled in the cavity (106) due to the higher relative permittivity of the solid material structure (114) than the cavity (106); The chamber (106) is configured to contain a mineral material for moisture measurement; and The probe device (108) is configured to output a frequency response of the resonator (100) affected by the mineral material for use in determining a moisture content of the mineral material.

2. The measuring device according to claim 1, characterized in that The solid material structure (114) of the resonator (100) comprises zirconium oxide ZrO2.

3. The measuring device according to claim 1, characterized in that The relative permittivity of the solid material structure (114) is in the range of 20 to 100.

4. The measuring device according to claim 1, characterized in that The measuring device comprises a data processing unit (120) configured to determine a density-compensated moisture content of the mineral material based on a frequency response of the resonator (100) affected by the mineral material.

5. The measuring device according to claim 4, characterized in that The data processing unit (120) is configured to determine the density-compensated moisture content of the mineral material based on at least two of the following frequency responses: a resonant frequency of the resonator (100), a Q value of the resonance, and a signal level of the resonance.

6. The measuring device according to claim 4, characterized in that The data processing unit (120) comprises one or more processors (700); and one or more memories (702) comprising computer program code; The one or more memories (702) and the computer program code are configured to, together with the one or more processors (700), cause a data processing unit (120) to determine a moisture content of the mineral material based at least on a frequency response of the resonator (100) affected by the mineral material.

7. The measuring device according to claim 1, characterized in that The measuring device comprises two sample feed systems (200, 202), wherein a first sample feed system (200) is configured to feed mineral material at a first volume flow rate towards a second sample feed system (200, 202), and the second sample feed system (202) is configured to feed mineral material to and through a cavity (106) of the resonator (100) at a second volume flow rate, the second volume flow rate being greater than the first volume flow rate.

8. The measuring device according to claim 1, characterized in that The measuring apparatus is configured to measure mineral materials comprising ferromagnetic and / or ferrimagnetic material.

9. The measuring device according to claim 1 or 8, characterized in that The measuring device is configured to measure mineral material comprising magnetite and / or hematite.

10. The measuring device according to claim 1, characterized in that The probe device (108) comprises a first coupling probe (300) and a second coupling probe (302), wherein an angle α between a radial line from the second coupling probe (302) to the longitudinal axis (LA) of the resonator (100) and a radial line from the first coupling probe (300) to the longitudinal axis (LA) of the resonator (100) is π / 2, and a length of a radial line from the second coupling probe (302) to the longitudinal axis (LA) of the resonator (100) is d.

11. The measuring device according to claim 1, characterized in that The probe arrangement (108) comprises a pair of feeding probes (310, 312) at positions (l, β), wherein l is a radial distance from a longitudinal axis of a resonator (100) for the pair of feeding probes (310, 312), an angle β between the pair of feeding probes (310, 312) is π, and the measuring device is configured to feed the pair of feeding probes (310, 312) with signals having the same phase to both of them so as to eliminate interfering resonances (402) having a frequency different from the measured resonance frequency (400).

12. The measuring device according to claim 1, characterized in that The solid material structure (114) is a plate having a hole (105) therethrough, the hole (105) being located inside the periphery (112), and the hole (105) comprising a cavity (106); The measuring device comprises a conduit (104) connected to the aperture (105), the conduit (104) being configured to allow mineral material to flow through the measuring device; The measuring device comprises a layer (124) of electrically conductive material located on a plate of the solid material structure (114) and on the pipe (104).

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