Electromagnetic control process for mine slurry mixing

Abstract

The present application belongs to the technical field of mine slurry processing, and relates to an electromagnetic regulation and control process for mixing mine slurry, comprising: introducing mine slurry into a mixing space and mixing in wear-resistant ferrite powder, controlling a magnetic field generation unit to generate a rotating magnetic field to drive the wear-resistant ferrite powder and the slurry matrix to rotate; collecting an induced current characteristic signal of the magnetic field generation unit and analyzing the time rate of change of the third harmonic amplitude, when the rate of change is in a steady state limit, switching the rotating magnetic field to a reverse pulse magnetic field, and destroying the synchronous rotation state of the mine slurry through the shear stress generated by the reverse torque, the present application breaks the rigid bottleneck of high viscosity medium by using the physical difference between the rapid response of electromagnetic poles and the lag of fluid motion, enhances the relative slip between the slurry layers, and ensures high uniformity of material mixing while reducing the thermal dissipation of electromagnetic energy.

Description

Technical Field

[0001] This invention belongs to the field of mining slurry treatment technology, and more specifically, this invention relates to an electromagnetic control process for mixing mining slurries. Background Technology

[0002] Currently, in mineral processing and tailings cemented backfilling processes, the mixing uniformity of high-concentration non-Newtonian slurries directly affects the physical and mechanical properties of downstream products. Slurry mixing generally adopts a mechanical shaft system to drive the blade rotation, using physical shear force to propel the slurry flow. When the slurry mass concentration increases, the slurry exhibits strong abrasiveness and high yield stress characteristics. Traditional contact mixing faces maintenance pressure due to frequent blade replacement. At the same time, the unique rheological properties of non-Newtonian fluids cause kinetic energy input to concentrate near the blades, forming a settling dead zone at the edge of the mixing chamber.

[0003] To address mechanical wear, the industry has attempted to directly drive fluids using alternating electromagnetic fields. However, existing electromagnetic control logic treats the slurry as a passive physical load. Under continuous unidirectional electromagnetic thrust, high-concentration slurries are prone to generating synchronously rotating rigid flow states, causing the relative angular velocity difference between fluid micro-elements to disappear. At this point, the energy input to the system is mainly converted into heat loss to overcome cavity wall friction, and the rheological network does not undergo substantial shearing and fragmentation. Not only are there limitations in the physical driving form at the hardware level, but existing magnetic field control methods also have shortcomings. For example, Chinese invention patent application CN121827848A discloses a method for directional grouting of water-rich fractured surrounding rock based on an external magnetic field. The viscosity of the medium is reduced by switching between a low-frequency rotating magnetic field and a high-frequency alternating magnetic field, allowing it to penetrate into micro-fractures. The establishment of the control mechanism implicitly depends on extremely stringent objective conditions: the existence of a complex network of solid geological fractures as a static physical constraint, and the obstruction of auxiliary fluid dispersion by the solid walls of narrow channels. The logic of simply relying on frequency conversion to reduce viscosity is shifted to the non-Newtonian slurry mixing condition in an open volumetric tank. The external solid boundary provides a strong shear resistance environment. Under the continuous drive of the magnetic field, the internal micro-elements of the high-concentration medium are extremely lacking in the objective physical conditions of relative slip, and the fundamental physical constraint boundary is mismatched. This causes the open flow field to eventually fall into the synchronous rotation rigid body dead zone, unable to spontaneously tear the yield stress network inside the fluid.

[0004] Therefore, the technical problem to be solved by this invention is how to use the rapid response of electromagnetic fields to strip fluid micro-elements in real time based on the evolution law of slurry rheological properties, thereby reducing equipment wear and eliminating the mixing dead zone of high viscosity media. Summary of the Invention

[0005] This invention provides an electromagnetic control process for mixing mining slurries, comprising the following steps: Step 101: Introduce a mining slurry with a mass concentration of 65% to 72% into the mixing space, and mix in wear-resistant ferrite powder accounting for 0.8% to 1.2% of the total mass of the mining slurry; Step 102: Control the magnetic field generating unit to generate a rotating magnetic field in the mixing space, so that the wear-resistant ferrite powder moves inside the mining slurry and drives the slurry matrix to rotate. Step 103: Collect the characteristic signal of the induced current of the magnetic field generating unit, analyze the amplitude of the third harmonic in the characteristic signal of the induced current through high-order filtering, and calculate the rate of change of the amplitude of the third harmonic with time to obtain the rate of change of the harmonic component characterizing the integrity of the yield stress network inside the mine slurry. Step 104: When the rate of change of the harmonic components drops to within the preset steady-state limit, the control magnetic field generating unit switches the rotating magnetic field to a reverse pulse magnetic field. The reverse pulse magnetic field generates a reverse torque on the mining slurry with rotational momentum, and generates shear stress inside the mining slurry to eliminate the synchronous rotation state of the mining slurry. Step 105: After the rate of change of harmonic components rises back to the preset flow threshold, the magnetic field output of the magnetic field generating unit is stopped, so that the mine slurry generates turbulent diffusion under the action of momentum.

[0006] Preferably, the wear-resistant ferrite powder is barium ferrite powder, the average particle size of the wear-resistant ferrite powder is 10μm to 50μm, and the surface of the wear-resistant ferrite powder is provided with an alumina wear-resistant layer with a thickness of 100nm to 300nm; wherein, the alumina wear-resistant layer is used to reduce the collision loss between the wear-resistant ferrite powder and mineral particles in the mining slurry under the alternating drive of the rotating magnetic field and the reverse pulse magnetic field.

[0007] Preferably, in step 102, the frequency of the rotating magnetic field increases linearly with the apparent viscosity of the ore slurry, and the magnetic induction intensity of the rotating magnetic field is distributed in a gradient from the center to the edge of the mixing space.

[0008] Preferably, step 103 is further refined as follows: the fundamental component in the induced current characteristic signal is filtered out by a high-order bandpass filter to obtain harmonic characteristic data characterizing the nonlinear response of the mine slurry.

[0009] Preferably, in step 104, the pulse width of the reverse pulse magnetic field is 50ms to 200ms, and the peak value of the magnetic induction intensity of the reverse pulse magnetic field is not less than 1.5 times the peak value of the magnetic induction intensity of the rotating magnetic field.

[0010] Preferably, between step 104 and step 105, the following step is also included: adjusting the phase difference of the magnetic field generating unit to generate an axially reciprocating electromagnetic thrust in the mixing space to suppress the gravitational settling of the mine slurry.

[0011] Preferably, at different height positions in the mixing space, the magnetic field generating unit generates a bottom magnetic field and an upper magnetic field with a frequency difference to generate longitudinal shear force inside the mining slurry.

[0012] Preferably, in step 105, the preset flow threshold is calibrated based on the minimum point of the rate of change of harmonic components.

[0013] Preferably, after step 105, the following steps are also included: monitoring the mixing intensity characteristics at the bottom of the mixing space, and restarting step 102 when the mixing intensity characteristics are lower than a preset intensity and the duration exceeds a preset duration.

[0014] The embodiments of the present invention have at least the following beneficial effects: Firstly, in the electromagnetic control of mining slurry mixing, by instantaneously reversing the polarity of the magnetic field and the spatiotemporal misalignment between the mechanical inertia of the mining slurry, this process constructs a high-intensity surface velocity gradient between barium ferrite powder and the slurry matrix. This physical mechanism utilizes the extreme speed of electromagnetic field response and the hysteresis of high-concentration non-Newtonian fluid motion to transform the reverse impact of the magnetically driven carrier into shear force that tears the yield stress network inside the slurry, eliminating the rigid body rotation phenomenon generated by high-viscosity media under continuous unidirectional drive, and causing the fluid micro-elements in the mixing space to switch from a synchronous rotation state to a violent interlayer relative slip state.

[0015] Secondly, the harmonic characteristics of the induced current in the excitation coil array are used as a physical probe of the slurry rheological state. The system monitors the amplitude and rate of change of the third harmonic to visualize the structural integrity and flow consistency of the slurry in the mixing chamber in real time. When the harmonic characteristics show that the slurry has entered a shear-free rotational steady state, a reverse pulse output is triggered. When the fluid network is determined to be in a state of global collapse and the apparent viscosity is reduced to the minimum point, the energy input is actively cut off. This mechanism not only precisely locks the external work at the critical stage of overcoming the fluid yield strength, but also guides the slurry to use residual kinetic energy to perform passive turbulent diffusion. While maintaining global mixing uniformity, it avoids ineffective electromagnetic heating loss under high viscosity conditions.

[0016] Third, by setting bottom coils and top coils with frequency difference in the mixing space along the axis, this process constructs a longitudinal shear slip surface inside the slurry. The output frequency of the bottom coil is set to be greater than that of the top coil, generating an angular velocity gradient from bottom to top. This difference in rotational speed in the spatial dimension forcibly cuts off the bottom particle agglomeration network caused by gravity settling, realizing the dynamic balance of slurry gradation in the vertical direction in the mixing space, effectively solving the common problems of bottom accumulation and layered distribution in deep cavity industrial mixing tanks. Attached Figure Description

[0017] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings, in which several embodiments of the invention are illustrated by way of example and not limitation, wherein: Figure 1 This invention relates to a flowchart of the electromagnetic control process for mixing mining slurries. Figure 2 This is a functional interaction diagram of the magnetic field generating unit and the sensing monitoring logic involved in the present invention. Detailed Implementation

[0018] The principles and spirit of the present invention will now be described with reference to several exemplary embodiments in conjunction with the accompanying drawings. It should be understood that these embodiments are provided merely to enable those skilled in the art to better understand and implement the present invention, and are not intended to limit the scope of the present invention in any way. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0019] Example 1: This example relates to an electromagnetic control process for mixing mining slurries, including the following steps: Step 101: Introduce a mining slurry with a mass concentration of 65% to 72% into the mixing space, and mix in wear-resistant ferrite powder accounting for 0.8% to 1.2% of the total mass of the mining slurry; Step 102: Control the magnetic field generating unit to generate a rotating magnetic field in the mixing space, so that the wear-resistant ferrite powder moves inside the mining slurry and drives the slurry matrix to rotate. Step 103: Collect the characteristic signal of the induced current of the magnetic field generating unit, analyze the amplitude of the third harmonic in the characteristic signal of the induced current through high-order filtering, and calculate the rate of change of the amplitude of the third harmonic with time to obtain the rate of change of the harmonic component characterizing the integrity of the yield stress network inside the mine slurry. Step 104: When the rate of change of the harmonic components drops to within the preset steady-state limit, the control magnetic field generating unit switches the rotating magnetic field to a reverse pulse magnetic field. The reverse pulse magnetic field generates a reverse torque on the mining slurry with rotational momentum, and generates shear stress inside the mining slurry to eliminate the synchronous rotation state of the mining slurry. Step 105: After the rate of change of harmonic components rises back to the preset flow threshold, the magnetic field output of the magnetic field generating unit is stopped, so that the mine slurry generates turbulent diffusion under the action of momentum.

[0020] The wear-resistant ferrite powder described in this embodiment is barium ferrite powder. The average particle size of the wear-resistant ferrite powder is 10μm to 50μm, and the surface of the wear-resistant ferrite powder is provided with an alumina wear-resistant layer with a thickness of 100nm to 300nm. The alumina wear-resistant layer is used to reduce the collision loss between the wear-resistant ferrite powder and mineral particles in the mining slurry under the alternating drive of the rotating magnetic field and the reverse pulse magnetic field.

[0021] In step 102 of this embodiment, the frequency of the rotating magnetic field increases linearly with the apparent viscosity of the mining slurry, and the magnetic induction intensity of the rotating magnetic field is distributed in a gradient from the center to the edge of the mixing space.

[0022] Step 103 in this embodiment is further refined as follows: the fundamental component in the induced current characteristic signal is filtered out by a high-order bandpass filter to obtain harmonic characteristic data characterizing the nonlinear response of the mine slurry.

[0023] In step 104 of this embodiment, the pulse width of the reverse pulse magnetic field is 50ms to 200ms, and the peak value of the magnetic induction intensity of the reverse pulse magnetic field is not less than 1.5 times the peak value of the magnetic induction intensity of the rotating magnetic field.

[0024] Between steps 104 and 105 in this embodiment, the following step is also included: adjusting the phase difference of the magnetic field generating unit to generate an axially reciprocating electromagnetic thrust in the mixing space to suppress the gravity settling of the mine slurry.

[0025] In this embodiment, at different height positions in the mixing space, the magnetic field generating unit generates a bottom magnetic field and an upper magnetic field with a frequency difference to generate longitudinal shear force inside the mining slurry.

[0026] In step 105 of this embodiment, the preset flow threshold is calibrated based on the minimum point of the harmonic component change rate.

[0027] After step 105 in this embodiment, the following steps are also included: monitoring the mixing intensity characteristics at the bottom of the mixing space, and restarting step 102 when the mixing intensity characteristics are lower than the preset intensity and the duration exceeds the preset duration.

[0028] Example 2: In this example, in an iron ore beneficiation plant with an annual output of 5 million tons, the volume is 50m³. 3 A 70% (w / w) mineral slurry was introduced into a deep-cavity mixing tank. This slurry exhibited strong abrasiveness and high yield stress. Simultaneously, 1.0% (w / w) of wear-resistant ferrite powder, with an average particle size of 30 mm, was mixed into the slurry. The magnetic field generating unit produces a rotating magnetic field within the mixing space, causing the wear-resistant ferrite powder to move within the mineral slurry and drive the slurry matrix to rotate. The power drive module of the magnetic field generating unit outputs excitation current according to the initially set frequency. As the mixing time increases, the mineral slurry enters a synchronous rotation state, resulting in a decrease in the relative velocity difference between fluid micro-elements. The induced current characteristic signal of the magnetic field generating unit is acquired through a high-order filter circuit, and the amplitude of the third harmonic in the induced current characteristic signal is analyzed. And calculate the amplitude of the third harmonic. rate of change over time The rate of change of harmonic components, which characterizes the integrity of the yield stress network inside the mine slurry, was obtained.

[0029] When the rate of change of harmonic components When the voltage drops to the preset steady-state limit range of 0 to 0.05, it is determined that the mine slurry forms a rigid fluid column that rotates synchronously as a whole. In order to achieve an extremely fast response of electromagnetic field polarity on a whole scale and suppress transient high voltage generated by inductive load, the magnetic field generating unit is driven by an IGBT-based full-bridge inverter circuit, and an overvoltage suppression module consisting of an RC absorption circuit and a varistor is connected in parallel at the power output terminal. The 10ms switching time refers to the time window from when the excitation controller issues a phase reversal command to when the drive current passes through the zero point and completes the 180-degree phase reconstruction. In actual execution, the inverter circuit uses soft-switching control technology to adjust the current near the zero point. By switching the power transistor on and off, and thus preventing the induced electromotive force from damaging the insulation layer, the rising edge of the reverse pulse magnetic field generates a reverse electromagnetic torque sufficient to disrupt the inertia of the slurry in a very short time. Within 10ms, the magnetic field generating unit switches the rotating magnetic field to a reverse pulse magnetic field, which generates a reverse torque on the mining slurry with rotational momentum. The hysteresis effect caused by the reverse torque and the fluid's inertia produces transient shear stress between the slurry layers, disrupting the continuity of the rigid fluid column and eliminating the synchronous rotation state within the slurry. From the physical essence of the synergistic interaction between fluid dynamics and microdynamics... Because the volume of the mineral slurry in the mixing tank reaches 50m³ and has a high moment of inertia, and the barium ferrite powder with an alumina wear-resistant layer on its surface, as a discrete magnetic micro-element, accounts for only 1.0% of the mass, the electromagnetic polarity reversal on the 10ms timescale cannot directly and instantaneously decelerate the macroscopic large-volume fluid. Instead, it first acts on the billions of ferrite powder micro-elements distributed in the matrix grid micro-region. In the actual time flow sequence of control, eliminating the reverse current oscillation and entering a stable output state within 2ms means that the other set of inverter power transistors in the diagonal direction receives a high-level drive after the dead time ends and begins reverse conduction. Starting from the absolute moment as time zero, the reverse impact current, under the combined clamping action of the high-frequency RC absorption circuit and the varistor, can completely limit the amplitude of the high-frequency parasitic oscillation to within 1% of the fundamental amplitude after 2 milliseconds of damping attenuation. This allows the control system to obtain a stable, high-frequency glitch-free rising edge of the reverse pulse waveform in the early stage of reverse growth. The total time window of 10 milliseconds refers to the complete hardware physical process that includes the excitation controller issuing the interrupt commutation command, waiting for the previous set of power transistors to be completely turned off, the 50-microsecond hardware dead zone transition, and the subsequent reverse excitation current growing to the target maximum amplitude intensity without oscillation.In other words, the control system can eliminate the transient electromagnetic oscillations introduced by commutation within the first 2 milliseconds after the power transistor triggers the switch, and then allow the current to grow smoothly along the slope of the ideal pulse rising edge without oscillation to the design peak value within the following 8 milliseconds. This perfectly constructs the maximum amplitude output of the reverse pulse magnetic field at the end of the 10-millisecond time window. The two have a progressive relationship of inclusion and being included at the timing boundary, thus ensuring the self-consistency and stability of the state flow of the large inductive load. Under the instantaneous reversal drive of the reverse pulse magnetic field, these powder micro-elements burst out in situ with a reverse micro-electromagnetic impact torque within 10ms, which, due to the mechanical motion lag, still maintains the high-speed rotation of the macro-slurry in the original direction. Between the matrices, a cross-scale local relative velocity slip surface is forcibly torn open. The shear impulse generated by the relative velocity gradient in this micro-region instantly exceeds the yield limit of the gel structure inside the slurry. This causes spontaneous and efficient outward radiation through the local chain collapse of the micro-stress grid, ultimately rapidly disintegrating the continuous structure of the entire rigid rotating fluid column at the macroscopic level. The key physical chain for achieving cross-scale momentum transfer within an extremely short timescale lies in the fact that when the applied rotating magnetic field completes polarity reversal within 10 milliseconds, the direction of the magnetic field vector in space undergoes a 180-degree abrupt change. At this point, each barium ferrite powder micro-element uniformly suspended within the slurry grid micro-region acts as an independent magnetic dipole, and its own... The direction of the magnetization intensity is completely opposite to the direction of the external magnetic field after the instantaneous reversal, thus spontaneously inducing an extremely high reverse magnetic torque at the microscopic particle level. Since the average particle size of a single barium ferrite powder is only 10 to 50 micrometers, its mechanical inertia of microscopic rotation is extremely small. Under the action of the reverse magnetic torque, its microscopic relaxation time to overcome the local resistance of the surrounding medium and complete the in-situ spin polarization reversal is less than 1 millisecond, which is far lower than the macroscopic commutation time window of 10 milliseconds. Therefore, within 10 milliseconds of the zero-crossing reverse growth of the excitation current, billions of barium ferrite micro-elements have converted their stored electromagnetic energy into microscopic local momentum pointing in the opposite direction through spin polarization actions that precede those of the macroscopic fluid, and expressed as micro-elemental surface The alumina wear-resistant layer on the surface forms a hard shear interface, forcibly causing relative motion between it and the tightly wrapped mineral slurry fluid micro-elements. Within 10 milliseconds, this microscopic shear force, through momentum exchange and physical collisions between multiphase fluid particles, radiates outwards in a network-like form as microscopic shear waves from the particle surface. The local shear stress rapidly exceeds the yield limit formed by the mesh structure of the high-concentration mineral slurry, triggering microscopic cracks in the gel network and a chain reaction-like collapse. Thus, without relying on the macroscopic solid-phase boundary constraints of the tank, and through the transient spatiotemporal misalignment between the microscopic discrete magnetic drive carrier and the macroscopic high-hysteresis fluid matrix, electromagnetic reversal energy is precisely converted into macroscopic interlayer slip work for directional tearing of the high-yield-stress network.

[0030] To address the issue of sedimentation and accumulation at the bottom of the mixing tank, the magnetic field generating unit independently adjusts the coil array along the height of the mixing tank, setting the output frequency of the bottom excitation coil. Greater than the output frequency of the central excitation coil The momentum transfer intensity generated at the bottom is higher than that at the top, creating an angular velocity gradient in the vertical direction. This generates an upward flow that propels the bottom sediments towards the mixing center. When the rate of change of harmonic components is monitored... When the flow threshold rises to above 0.15, it is determined that the yield network inside the mine slurry has collapsed globally, and the flow field has returned to a turbulent diffusion mixing state.

[0031] Example 3: In this example, on a mining slurry mixing test platform with a processing capacity of 500 kg, the experimental group used iron concentrate slurry with a mass concentration of 70% as the material to be mixed, and added wear-resistant ferrite powder with a mass ratio of 1.0%. This powder was screened through a 325-mesh standard sieve to ensure particle size distribution. The magnetic field generating unit consisted of 6 symmetrically distributed excitation coils, and its power drive module provided three-phase AC power with a frequency of 50 Hz. The frequency of experimental data acquisition was... The sampling frequency is determined based on the fundamental frequency of the excitation current and the harmonic order to be analyzed. To balance the sampling resolution of the characteristic signal with the computational load of the background control unit, the sampling frequency is... The test environment was set to 1000Hz, and broadband electromagnetic noise with a signal-to-noise ratio of 20dB was actively superimposed to simulate the electromagnetic interference generated by the operation of large power equipment in the mine.

[0032] During operation, the sensor collected the induced current characteristic signal of the magnetic field generating unit and extracted its raw waveform data. The raw signal contained non-stationary components caused by slurry movement. The system used a high-order bandpass filter to cut off the frequency band around 150Hz and analyzed the amplitude of the third harmonic in the induced current characteristic signal. When the mine slurry is in a turbulent mixing state, the measured Fluctuating between 1.25A and 1.38A, the rate of change of harmonic components... The value is greater than 0.20. As the mixing time increases to 120 s, the slurry enters a synchronous rotation state, and the shear stress inside the fluid decreases. At this time, the measured value is... The value rose to 2.15A, and The value decreased and stabilized at around 0.03. The magnetic field generating unit detected... Once within the steady-state limit range of 0 to 0.05, the excitation current phase is flipped 180 degrees within 10 ms, resulting in a step change in the induced current characteristic signal. This reflects the transition from rigid body rotation to shear state within the flow field. In the aforementioned discrete calculation of the rate of change, to match the high-speed fixed-point calculation of the controller and highlight the high-frequency small fluctuations under turbulent conditions, the system performs a preset scale-normalized gain amplification on the amplitude difference. Therefore, when the sampling point interval... When the time step reference in the discrete difference operator is 1ms, the dimensionless rate of change of its calculated output is... During the turbulent and violent fluctuation phase, the gain can be effectively amplified to above 0.20, while in the steady-state phase of synchronous rotation, it smoothly converges to around 0.03, achieving precise alignment between data processing and the physical requirements of macroscopic flow state identification. The pure text logic steps of the scale normalization gain amplification processing are as follows: The microcontroller first subtracts the third harmonic amplitude extracted at the current nth sampling moment from the third harmonic amplitude at the previous (n-1)th sampling moment to obtain the absolute difference of amplitude within the current sampling step, and temporarily stores it in the first register; subsequently, the system retrieves a normalized reference denominator factor pre-calibrated based on the amplitude of the no-load standard excitation current from the read-only memory. This reference denominator factor is numerically equal to 10 times the average amplitude of the background noise output by the high-order bandpass filter under the no-load operating state of the system. The controller controls the arithmetic logic unit to divide the absolute difference of amplitude in the first register by the normalized reference denominator factor, thereby eliminating the dimensional influence caused by the sensor's physical gain drift and obtaining a basic dimensionless relative rate of change. Finally, in order to cooperate with the integer arithmetic rules of the fixed-point processor and artificially amplify the high-frequency discrete jumps of the signal in the turbulent micro-region, the system retrieves a preset fixed amplification gain coefficient, which is set to an integer of 100. The multiplier directly multiplies the aforementioned dimensionless relative rate of change by this integer 100, and the final output product is stored in the judgment queue as the final dimensionless rate of change data. Through these two steps of pure text derivation logic, the originally tiny amplitude fluctuations can be transformed into dimensionless discrete scalars suitable for high-speed comparison by the microprocessor, realizing a high-sensitivity closed loop for feature recognition.

[0033] To determine the synergistic effect and parameter boundaries of this process, three control groups were set up. Control group 1 used a unidirectional continuous magnetic field drive without switching to a reverse pulse magnetic field. The measured coefficient of variation for mixing uniformity was 18.5%, and the energy utilization rate decreased by 22% due to wall heat loss caused by synchronous fluid rotation. Control group 2 adjusted the addition ratio of wear-resistant ferrite powder to 0.5%. Due to insufficient number of driven micro-elements in the slurry, the measured induced current intensity of the magnetic field generating unit decreased by 45%, leading to... The extraction signal-to-noise ratio was lower than the judgment threshold and could not trigger the reverse pulse magnetic field. Control group 3 increased the mass concentration of the mine slurry to 75%. The results showed that the yield stress exhibited by the slurry exceeded the maximum magnetic torque provided by the rotating magnetic field, and the slurry matrix could not initiate rotation within 600s. This indicates that a mass concentration of 65% to 72% is the working window for this process. The experimental group using the method of this invention measured the final sample's component variation coefficient to be 4.2%, and compared to control group 1, the mixing uniformity was improved by 77.3%. Under the closed-loop control of the indicators, 85% of the output energy of the magnetic field generating unit is converted into shear work to tear the local structure of the slurry network, avoiding the formation of rotation dead zones in the slurry. Experimental data proves that this process uses the evolution law of the third harmonic characteristic signal to identify the abrupt change point of the fluid motion state, and breaks the rigid body bottleneck of non-Newtonian fluid through the impact effect of the pulsed magnetic field on the fluid inertia, so as to achieve homogeneous mixing of high-concentration mining slurry.

[0034] Example 4: This example has a processing capacity of 200m³ / hour. 3 Within the deep-well cemented backfilling station, a 72% mass concentration of tailings slurry is introduced into the mixing space. This tailings slurry contains particles with an average diameter of 45 mm. To improve the coupling efficiency of non-contact drive, 1.2% by mass of wear-resistant ferrite powder is added to the silicate particles. This powder is obtained by selective magnetite mining, and its saturation magnetization intensity is measured to be between 50 emu / g and 55 emu / g by a vibrating sample magnetometer. The reference power supply frequency of the industrial control power grid is set to 50 Hz. According to the principle of electromagnetic induction Fourier harmonic decomposition, the center frequency of the third-order nonlinear hysteresis distortion signal corresponds to 150 Hz. The system determines the filter passband parameters accordingly.

[0035] The power drive module outputs excitation current according to a preset self-test sequence. The magnetic field generating unit collects the characteristic signal of the induced current in the mixed space through the induction coil. The back-end processor performs a discrete Fourier transform on the induced current sequence and extracts the amplitude of the third harmonic using a Butterworth digital bandpass filter with an order of 6 and a cutoff frequency set between 145Hz and 155Hz. Calculate the amplitude of the third harmonic. At a fixed sampling interval The change within the harmonic components is calculated using the following formula to obtain the rate of change of the harmonic components. : ;in, The rate of change of harmonic components, For the first The third harmonic amplitude at each sampling time. For the first The third harmonic amplitude at each sampling time. The sampling interval is 1ms. To accurately identify minimum points from induced current signals with random noise, the system performs a fifth-order median filter on the original harmonic data before calculating the rate of change, and utilizes a length of... A sliding window is used to monitor the slope of the rate of change sequence in real time; when the sliding window is within... continuous When a cycle is in a monotonically decreasing state and closely follows a monotonically increasing trend, the system records this inflection point as a minimum point, serving as a zero-time reference for calibrating subsequent flow thresholds. This effectively filters out transient numerical artifacts caused by grid fluctuations or local flow field disturbances. During the execution of the hardware control program, the length of the sliding window... Numerically, the number of discrete sampling points is precisely set to 50, corresponding to a real physical time span of 50 milliseconds. This time span perfectly covers a complete low-frequency electromagnetic interference cycle caused by the switching action of a high-power frequency converter in a mine. The number of continuous cycles, *m*, used to determine the monotonicity of the flow transition is precisely set to an integer of 5, corresponding to 5 consecutive discrete calculation cycles output by the sliding window. The specific software logic identification action is as follows: the microcontroller constructs a 50-bit first-in-first-out circular queue in memory, sequentially pushing the calculated rate of change values ​​output every millisecond into the queue, and calculating... The average slope of the 50 data points in the current window; when the processor detects that the average slope of the output of the circular queue remains negative for 5 consecutive calculation cycles, and the average slope of the subsequent 5 adjacent calculation cycles immediately flips and remains positive, the algorithm determines that there is a monotonic minimum mutation point of the rheological physical state at the boundary between the two consecutive 5 cycles, and then locks the time scale at this position as the zero-time reference for recalculating the flow threshold. By limiting the specific window and cycle parameters, a filtering and identification closed loop that takes into account both noise resistance and response speed is established at the bottom layer of the fixed-point software.

[0036] For the calibration of steady-state limits, the process involves pre-measuring the rheological curve of the entire tailings slurry at a yield stress of 120 Pa, determining that the upper limit of the rate of change of harmonic components when the flow field enters a synchronous rotational steady state is 0.05. When monitoring... When the steady-state limit range of 0 to 0.05 is reached and the duration reaches 300 ms, the power bridge of the magnetic field generating unit is reverse-conducted, switching the rotating magnetic field to a reverse pulse magnetic field within 10 ms. This transient reverse torque impact disrupts the rigid fluid structure of the entire tailings slurry. The magnetic field generating unit has three sets of excitation coils arranged vertically along the height of the mixing tank. The current phase difference between the bottom and middle excitation coils is set to 120 degrees. An upward electromagnetic thrust component is generated using the vector synthesis of spatial phases. The output frequency of the bottom excitation coil is set to 75 Hz, making the angular velocity of the bottom wear-resistant ferrite powder 1.5 times that of the upper powder. The resulting angular velocity gradient cuts off the bottom deposition layer and induces displacement exchange of slurry components in the vertical direction. Monitoring... After exceeding 0.15, the entire tailings slurry returned to a turbulent mixing state, and the solid content deviation at different height sampling points within the mixing space was measured to be less than 0.5%.

[0037] Example 5: In this example, in a new mixed operating environment deployed in a mineral processing line, the magnetic field control unit runs a baseline calibration process for the current batch of iron concentrate slurry. The magnetic field generating unit drives the slurry with a mass concentration of 70% to rotate at an excitation frequency of 50Hz. Electromagnetic induction sensors distributed on the outer wall of the mixing tank acquire the characteristic signal of the induced current at a frequency of 1000Hz. The processor uses discrete Fourier transform to analyze the amplitude of the third harmonic. And according to the sampling period Calculate the rate of change of harmonic components For the standard operating condition with a yield stress of 120 Pa, the amplitude change characteristics corresponding to the flow field entering the synchronous rotation state were measured to establish... A value of 0.045 is used as the logic threshold for triggering the reverse pulse magnetic field.

[0038] When fluctuations in material concentration cause a deviation in the fundamental amplitude of the induced current exceeding a preset 10%, the system reads the compensation parameters stored in the memory to correct the logic threshold. These compensation parameters are determined based on the correlation function between concentration and electromagnetic induction efficiency measured offline. Based on the physical law that the effective permeability of a multiphase flow system decreases non-linearly with the concentration of non-magnetic minerals, the system processor uses a calculation formula to obtain the compensation parameters. The calculation formula is: ;in, The online sampling mass concentration percentage value is dimensionless. The standard mass concentration is set to 70%. The calibrated dielectric decay constant is limited to a range of 0.15 to 0.25. After calculating the compensation parameters, the processor multiplies them by the initial logic threshold and outputs an updated pulse trigger reference. This correction step enables the magnetic field generating unit to identify abrupt changes in the flow field network state. The reverse pulse magnetic field applies a reverse torque within 10ms and tears the rigid structure inside the slurry. The online sampler at the bottom of the mixing tank measures that the component deviation at different heights within the mixing space remains below 0.5%. To completely eliminate the risk of numerical calculation failure caused by dimensional mismatch between percentage signs and discrete integers at the underlying digital operation level, the arithmetic logic unit of the controller runs a forced dimensional inversion interface before the operation is executed: the processor first de-symbolizes and purifies the online sampled mass concentration percentage value after smoothing and filtering. The system processes the data by directly extracting the preceding two Arabic numerals as a digital value and storing it in the second working register. Simultaneously, the constant calibration reference mass concentration retrieved from read-only memory also strictly uses an equivalent pure digital format, directly reading its two-digit integer value 70 without a percentage sign and storing it in the third working register. Subsequently, the subtractor directly subtracts the two-digit value 70 from the two-digit value in the third working register, thus calculating the pure digital difference at the same scalar dimension and order of magnitude. This pure digital difference is then multiplied by the dielectric decay constant, which is also dimensionless and in decimal form, and input as a pure digital exponent into the exponential function lookup table. This dimensionless conversion step ensures the consistency of the interface between the physical concentration of the multiphase flow system and the digital control quantity. The dielectric decay constant... The initial value, ranging from 0.15 to 0.25, is selected based on the average magnetic susceptibility and conductivity characteristics of the solid materials in the slurry to be mixed. When the slurry to be mixed is the non-magnetic tailings slurry in this embodiment, the electromagnetic induction efficiency decreases relatively gradually with fluctuations in material concentration due to the lack of strong magnetic components to absorb and shield electromagnetic waves. Therefore, the system calibration selects the lower limit of this constant, i.e., precisely sets it. The value is 0.15. However, when the production line switches to processing batches of strongly magnetic iron concentrate slurry, the high relative permeability of the iron concentrate particles creates local electromagnetic shielding and eddy current losses within the multiphase fluid. This causes the fundamental amplitude of the induced current to decrease exponentially with increasing slurry concentration. To provide sufficient compensation, the system calibration selects the upper limit of this constant, i.e., precisely sets it. The value is 0.25; if it is a mixed ordinary weakly magnetic metal ore slurry, then... By taking its arithmetic mean of 0.20, the compensation parameter can accurately reflect the fluctuation of the equivalent permeability of the multiphase flow through a one-to-one mapping between the initial value of the constant and the magnetic nature of the material.

[0039] Example 6: In this example, in an engineering site deployment environment for processing iron concentrate slurry, the system operates a standardized calibration procedure used to determine the steady-state limit range. The magnetic field generating unit outputs a 50Hz reference rotating magnetic field under no-load conditions and records the noise floor distribution of the induced current characteristic signal. A density of 2.8 g / cm³ is introduced into the mixing space. 3 Furthermore, a standard mining slurry sample with a mass concentration of 70% was simultaneously supplemented with 1.0% wear-resistant ferrite powder. The physical process of the slurry transitioning from a static to a synchronously rotating state was observed by step-by-step adjustment of the excitation current amplitude. The processor used a sixth-order Butterworth digital bandpass filter to analyze the amplitude of the third harmonic in the induced current characteristic signal. The rate of change of harmonic components was calculated using the first-order forward difference method. ,in, The amplitude of the third harmonic. The rate of change of harmonic components was recorded, and the characteristic value of the rate of change at the moment the slurry entered the rigid body rotation state was recorded. For the working condition of yield stress of 120 Pa, a system was established using repeatable test data from three sets of samples. The mapping relationship with slurry viscosity establishes an upper limit of 0.05 for the steady-state limit range.

[0040] When the system faces the electromagnetic induction efficiency drift caused by different batches of ore composition, the controller calculates the variance distribution of the fundamental amplitude of the induced current at 500 sampling points within the pre-inspection period on the time axis, extracts the characteristic components representing the intensity of environmental noise in the variance distribution, and corrects the upper limit of the steady-state limit. The correction coefficient is obtained by retrieving from the pre-stored offline calibration database. This procedure enables the magnetic field generating unit to identify the closed state of the yield stress network inside the flow field before the phase reversal of the excitation current. The reverse torque generated by the reverse pulse magnetic field within 10ms acts on the slurry micro-element and breaks the momentum balance between layers. The excitation coil array in the height direction of the mixing space uses a 120-degree phase difference to synthesize an upward axial thrust to counteract the component segregation caused by gravity settling. The component variation coefficient at different depths in the global range remains below 4.5%.

[0041] When handling online mixing conditions with continuous fluctuations in the concentration of mine slurry, the system operates on an adaptive reconstruction procedure of the reference characteristic matrix. The magnetic field control unit uses a pre-stored density and permeability mapping table in memory to determine the induced current attenuation coefficient at different concentrations. In the initial stage of material passing through the mixing space, the system uses a high-frequency sensor to detect the phase shift of the fundamental wave of the induced current and retrieves a logic criterion correction operator that matches the phase shift to perform real-time compensation for the steady-state limit. When the calculation result touches the upper limit of the corrected steady-state limit, the inverter circuit of the variable frequency power drive unit performs shutdown and reverse switching. The rising edge of the reverse pulse magnetic field induces an electromotive force that is 1.5 times higher than the rotating magnetic field within 2ms, causing the wear-resistant ferrite powder to generate high-frequency oscillation shear inside the slurry, thereby achieving real-time stability of the coefficient of variation of the mixing uniformity throughout the entire process.

[0042] The above description is only a few preferred embodiments of the present invention and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the embodiments of the present invention is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the above-mentioned inventive concept. For example, technical solutions formed by replacing the above-mentioned features with (but not limited to) technical features with similar functions disclosed in the embodiments of the present invention.

Claims

1. An electromagnetic control process for mixing mining slurries, characterized in that, Includes the following steps: Step 101: Introduce a mining slurry with a mass concentration of 65% to 72% into the mixing space, and mix in wear-resistant ferrite powder accounting for 0.8% to 1.2% of the total mass of the mining slurry; Step 102: Control the magnetic field generating unit to generate a rotating magnetic field in the mixing space, so that the wear-resistant ferrite powder moves inside the mining slurry and drives the slurry matrix to rotate. Step 103: Collect the characteristic signal of the induced current of the magnetic field generating unit, analyze the amplitude of the third harmonic in the characteristic signal of the induced current through high-order filtering, and calculate the rate of change of the amplitude of the third harmonic with time to obtain the rate of change of the harmonic component characterizing the integrity of the yield stress network inside the mine slurry. Step 104: When the rate of change of the harmonic components drops to within the preset steady-state limit, the control magnetic field generating unit switches the rotating magnetic field to a reverse pulse magnetic field. The reverse pulse magnetic field generates a reverse torque on the mining slurry with rotational momentum, and generates shear stress inside the mining slurry to eliminate the synchronous rotation state of the mining slurry. Step 105: After the rate of change of harmonic components rises back to the preset flow threshold, the magnetic field output of the magnetic field generating unit is stopped, so that the mine slurry generates turbulent diffusion under the action of momentum.

2. The electromagnetic control process for mixing mining slurry according to claim 1, characterized in that, The wear-resistant ferrite powder is barium ferrite powder with an average particle size of 10μm to 50μm. The wear-resistant ferrite powder surface is provided with an alumina wear-resistant layer with a thickness of 100nm to 300nm. The alumina wear-resistant layer is used to reduce the collision loss between the wear-resistant ferrite powder and mineral particles in the mining slurry under the alternating drive of rotating magnetic field and reverse pulsed magnetic field.

3. The electromagnetic control process for mixing mining slurry according to claim 1, characterized in that, In step 102, the frequency of the rotating magnetic field increases linearly with the apparent viscosity of the ore slurry, and the magnetic induction intensity of the rotating magnetic field is distributed in a gradient from the center to the edge of the mixing space.

4. The electromagnetic control process for mixing mining slurry according to claim 1, characterized in that, Step 103 is further refined as follows: the fundamental component in the induced current characteristic signal is filtered out by a high-order bandpass filter to obtain harmonic characteristic data that characterizes the nonlinear response of the mine slurry.

5. The electromagnetic control process for mixing mining slurry according to claim 1, characterized in that, In step 104, the pulse width of the reverse pulsed magnetic field is 50ms to 200ms, and the peak value of the magnetic induction intensity of the reverse pulsed magnetic field is not less than 1.5 times the peak value of the magnetic induction intensity of the rotating magnetic field.

6. The electromagnetic control process for mixing mining slurry according to claim 1, characterized in that, Between steps 104 and 105, the following steps are also included: adjusting the phase difference of the magnetic field generating unit to generate an axially reciprocating electromagnetic thrust in the mixing space to suppress the gravitational settling of the mine slurry.

7. The electromagnetic control process for mixing mining slurry according to claim 1, characterized in that, At different heights in the mixing space, the magnetic field generating unit produces a bottom magnetic field and an upper magnetic field with a frequency difference to generate longitudinal shear force inside the mine slurry.

8. The electromagnetic control process for mixing mining slurry according to claim 1, characterized in that, In step 105, the preset flow threshold is calibrated based on the minimum point of the rate of change of harmonic components.

9. The electromagnetic control process for mixing mining slurry according to claim 1, characterized in that, After step 105, the following steps are also included: monitoring the mixing intensity characteristics at the bottom of the mixing space, and restarting step 102 when the mixing intensity characteristics are lower than the preset intensity and the duration exceeds the preset duration.

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