A multi-stage physical separation and recycling process for sand washing wastewater

Abstract

The present application relates to sand washing wastewater solid-liquid separation processing technical field, disclose a kind of sand washing wastewater multistage physical separation and reuse process, comprising: control sand washing wastewater flows through main pipeline, utilize ultrasonic transducer and temperature sensor to collect ultrasonic attenuation ratio and temperature and generate dynamic concentration determination threshold;Comparison ultrasonic attenuation ratio and dynamic concentration determination threshold, when phase transition, adjust shunt valve opening to open shunt pressure relief pipeline, construct hydraulic parallel topology;According to the type of phase transition dynamic adjustment frequency of variable frequency mixer and backwater shunt valve opening, maintain the laminar state of sedimentation tank, the present application is mapped by ultrasonic attenuation characteristics Dynamic solid-phase grading to identify phase mutation, avoid mud overload and reuse pipe network pollution;Through valve opening complementary linear regulation to construct hydraulic parallel topology to relieve dynamic pressure impact, maintain sedimentation laminar stability and eliminate mud running phenomenon, improve system steady-state operation ability.

Description

Technical Field

[0001] This invention belongs to the field of solid-liquid separation and treatment technology of sand washing wastewater, and particularly relates to a multi-stage physical separation and reuse process for sand washing wastewater. Background Technology

[0002] Currently, in sand and gravel aggregate processing production lines, the multi-stage recycling process for large-volume slurry generated from washing manufactured sand typically employs a physical series architecture consisting of a coarse sand separator, a fine sand recovery machine, a gravity sedimentation tank, and a sludge filter press. Through the cascaded cooperation of gravity settling flow and mechanical screening field, solid waste is extracted from the aqueous phase, thereby achieving the process goals of purifying sand washing wastewater and classifying and recycling solid materials. When high and low frequency sound wave energy is transmitted in heterogeneous suspension, it generates specific scattering and absorption dissipation. Fine-diameter clay particles mainly scatter and dissipate high-frequency sound waves, while coarser-diameter micro-sand particles induce characteristic absorption in the large-wavelength sound wave flow field. By calculating the ratio of ultrasonic sound energy attenuation coefficients in the characteristic frequency band online, a deterministic physical image model of the solid particle gradation state inside the suspended slurry can be established.

[0003] In actual mining operations, the continuous movement of the stratum face leads to high-frequency and non-stationary distortions in the ratio of clay to fine sand components in the wastewater feed. Because the fixed-series process architecture implicitly relies on the assumption of constant solid phase gradation of the influent, a sudden increase in highly plastic fine mud results in insufficient residence time, causing the fine mud to overflow into the clear water network and severely wear down downstream nozzles. Conversely, a sudden increase in coarse-grained fine sand leads to rapid solidification, easily forming a dense mud layer at the bottom of the tank, disrupting the shear balance of the rake frame. Traditional processes often attempt to smooth out phase fluctuations by increasing the dosage of polymeric flocculants at a single point or blindly expanding the sedimentation tank volume. Hardware improvements such as adjusting the physical series configuration are constrained by rigid physical boundaries and cannot fundamentally address the two-phase separation imbalance caused by gradation mismatch. Besides hardware limitations, the control system also has shortcomings. For example, Chinese invention patent application CN112374653A discloses a sand... The hydraulic classification and fine sand recovery method for treating wastewater from stone production employs a PLC to adjust valve opening and closing or switch multiple tank groups based on the concentration difference fed back by the sediment concentration monitoring instrument in each separation tank. This scheme relies on the premise that the sediment forms a steady-state stratification inside the sedimentation tank, and cannot cope with high-frequency non-stationary phase distortion conditions. The control logic relies on the concentration difference feedback from downstream nodes, resulting in a delayed response. The intermittent valve action during path switching is prone to generating hydraulic instantaneous pressure and vibration pulses in the pipeline boundary layer. When the fluctuating fluid momentum is transmitted to the sedimentation zone, it tears the boundary layer of the ultrafine sludge blanket below the inclined plate, exacerbating the large-area sludge runoff. However, high concentrations of chemical residues can easily cause sludge to adhere to the wall and clog the solid-liquid filter components. When multiple channels are adjusted in a large-volume pipeline network, the rigid intermittent action of process switching will generate severe hydraulic instantaneous pressure and vibration pulses in the pipeline boundary layer. When the fluctuating fluid momentum is transmitted to the sedimentation zone, it will damage the boundary layer of the ultrafine sludge blanket below the inclined plate, causing large-area sludge runoff.

[0004] Therefore, the technical problem to be solved by this invention is how to construct a dynamic hydraulic topology adaptive adjustment mechanism for physical separation paths through fluid phase state acoustic non-sensory perception, and eliminate the disturbance of the multi-stage graded settling flow state by the impact dynamic pressure of the pipeline network during the phase change period. Summary of the Invention

[0005] This invention aims to solve the problem of erosion disturbance of multi-stage graded settling flow state by the impact dynamic pressure of the pipeline network during the phase change period by constructing a dynamic hydraulic topology adaptive adjustment mechanism for physical separation path through the acoustic non-sensory perception of fluid phase state.

[0006] In this technical solution, a multi-stage physical separation and reuse process for sand washing wastewater includes the following steps: Step S1: The sand washing wastewater is controlled to flow through the main inlet pipe at a velocity of 1.5 m / s to 1.8 m / s using a fluid supply pump. The ultrasonic attenuation ratio of the sand washing wastewater is collected by an ultrasonic transducer assembly installed inside the main inlet pipe. At the same time, the fluid temperature of the sand washing wastewater is collected by a temperature sensor. The fluid temperature is used to retrieve a preset temperature compensation coefficient to correct the basic concentration judgment threshold and generate a dynamic concentration judgment threshold. Step S2: The control unit compares the ultrasonic attenuation ratio with the dynamic concentration judgment threshold. When the ultrasonic attenuation ratio exceeds the dynamic concentration judgment threshold and a phase state change occurs, the control unit sends a timing control command to the pipeline valve assembly set at the diversion node of the main inlet pipeline. The vortex diversion valve and the sedimentation diversion valve are controlled to make inverse proportional complementary linear adjustment of the opening within 10s to 15s. The diversion and pressure relief pipeline connected in parallel with the main inlet pipeline is opened to construct a hydraulic parallel topology and reduce the transient dynamic pressure fluctuation rate inside the main inlet pipeline. In step S3, the control unit dynamically adjusts the rotation frequency of the variable frequency mixer at the bottom of the inclined plate sedimentation tank and the opening of the return water diversion valve of the clean water reuse pipeline according to the type of phase state transition. When the phase state transitions to clay-dominant, the rotation frequency of the variable frequency mixer is switched to the first rotation frequency range of 45 rpm to 60 rpm to generate mechanical shear force. Simultaneously, the return water diversion valve is adjusted to guide 20% of the overflow water of the inclined plate sedimentation tank to the front-end regulating tank, and the fluid Reynolds number in the inclined plate separation zone inside the inclined plate sedimentation tank is controlled to be in a laminar flow state of 100 to 300.

[0007] Preferably, in step S2, when the diversion and pressure relief pipeline is opened and a hydraulic parallel topology is constructed, the opening degree variation curves of the vortex diversion valve and the sedimentation diversion valve are mirror-symmetrical, and the fluid pressure variation rate inside the diversion and pressure relief pipeline is controlled within a preset safe range.

[0008] Preferably, step S1 includes the following sub-steps: Step S11, using an ultrasonic transducer assembly installed inside the main water inlet pipeline to alternately emit 5MHz high-frequency pulsed ultrasonic waves and 1MHz low-frequency pulsed ultrasonic waves to the fluid, and receiving the attenuated energy signal after penetrating the fluid to calculate the ultrasonic attenuation ratio; Step S12, using a temperature sensor installed on the coaxial side of the ultrasonic transducer assembly to continuously collect the fluid temperature inside the main water inlet pipeline.

[0009] Preferably, in step S3, the control of the first rotation frequency range includes the following sub-steps: Step S31, when the control unit determines that the phase state transition is a clay-dominant phase transition and the ultrasonic attenuation ratio is greater than or equal to the preset second preset threshold of 2.8 for three consecutive times, the control unit outputs a speed change command; Step S32, the variable frequency mixer responds to the speed change command and adjusts the rotation frequency to the first rotation frequency range of 45 rpm to 60 rpm.

[0010] Preferably, before step S1, the sand washing wastewater is sequentially introduced into the coarse sand collection unit and the fine sand recovery unit for coarse and fine mud sedimentation and separation. The separated slurry is introduced into the front-end equalization tank for mixing and then pumped into the main inlet pipeline using a fluid supply pump.

[0011] Preferably, in step S3, a settling inclined plate is arranged inside the inclined plate separation zone, the flow velocity of the fluid in the flow channel formed by the settling inclined plate is 0.02m / s to 0.05m / s, and after the variable frequency mixer has finished operating in the first rotational frequency range, the rotational frequency is reduced to 10rpm to 15rpm.

[0012] Preferably, in step S3, when adjusting the opening of the return water diversion valve, the valve opening of the return water diversion valve inside the clean water reuse pipeline is controlled to be 20% to 40%, and the overflow water from the inclined plate sedimentation tank is introduced into the front-end regulating tank through the return water diversion valve.

[0013] Preferably, after step S3, the sedimented sludge at the bottom of the inclined plate sedimentation tank is pumped to a filter press for dewatering treatment, the solid phase sludge cake is separated, and the resulting filter press filtrate is returned to the front-end equalization tank.

[0014] Preferably, when the phase transition is a phase transition to micro-sand-dominant phase transition and the ultrasonic attenuation ratio is less than or equal to 1.2, the control unit controls the vortex diversion valve to be fully open to 100% and controls the sedimentation diversion valve to be fully closed to 0%, so as to open the diversion and pressure relief pipeline and maintain the mud flow layer interface at the bottom of the inclined plate sedimentation tank within the preset height range.

[0015] Compared with existing technologies, the multi-stage physical separation and reuse process for sand washing wastewater of the present invention has the following advantages: 1. In the multi-stage physical separation and reuse process of sand washing wastewater, a dual-frequency ultrasonic transducer assembly is installed on the main pipeline of sand washing wastewater to emit high and low frequency ultrasonic waves. Utilizing the energy scattering and dissipation characteristics of particles of different sizes at specific frequencies, the ratio of high and low frequency energy attenuation coefficients is calculated online by the control unit to directly reflect the dynamic ratio of micro-sand to clay in the fluid. The ratio serves as the sole decision data source for diversion path scheduling, freeing the control strategy from the limitations of manual intermittent sampling and detection lag. The system responds autonomously based on transient changes in phase gradation, preventing a large influx of coarse particles into the sedimentation zone that could cause overload tripping of the sludge scraping mechanism, and also preventing a sudden increase in clay components that could pollute the production water reuse pipeline, effectively maintaining the long-term steady-state operation of the overall separation process.

[0016] 2. When the system determines that the fluid phase is dominated by micro-sand, the control unit closes the valve leading to the flocculation reaction zone and fully opens the control valve of the high centrifugal force field cyclone separation loop. This guides the wastewater to gather in the multi-stage micro-cyclone group to cut off the intervention of the polymer flocculant, allowing the sand particles to remain in a state without polymer encapsulation and settle rapidly by relying on strong centrifugal force. As the solid phase porosity increases, a smooth hydraulic sand discharge channel is formed inside the material layer, the solid-liquid two-phase separation resistance decreases, and the slag moisture content decreases accordingly. This eliminates the risk of coarse sand abrading the filter cloth of the subsequent filter press and causing embolism in the conveying pipeline, effectively reducing the mechanical structure failure rate of the entire solid-liquid separation system.

[0017] 3. When the system determines that the fluid phase is clay-dominant, the fluid is switched to a multi-stage inclined plate laminar flow sedimentation tank. The control unit sends progressively decreasing fluid shear commands to the stirring drive mechanism. Due to the removal of turbulent interference from coarse sand on the shear field, the fluid is stably maintained in a low Reynolds number laminar flow state in the inclined plate separation zone. With the action of the progressively decreasing shear energy field, fine clay particles rely on Coulomb forces to generate high-frequency collisions and agglomerate, thus accelerating the sedimentation of flocs. On this basis, the control unit adjusts the opening of the return water diversion valve of the clean water reuse pipeline to divert part of the overflow water from the laminar flow sedimentation tank to the front-end regulating tank to dilute the high-concentration influent water, which is used to level the material impact and maintain the constant and qualified physical indicators of the outlet reused water. Attached Figure Description

[0018] Figure 1 This is a flowchart of the node control process for the multi-stage physical separation and reuse of sand washing wastewater according to the present invention. Figure 2 This is a phase transition logic diagram of the multi-stage physical separation and reuse process for sand washing wastewater according to the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0020] A multi-stage physical separation and reuse process for sand washing wastewater includes the following steps: Step S1: The sand washing wastewater is controlled to flow through the main inlet pipe at a velocity of 1.5 m / s to 1.8 m / s using a fluid supply pump. The ultrasonic attenuation ratio of the sand washing wastewater is collected by an ultrasonic transducer assembly installed inside the main inlet pipe. At the same time, the fluid temperature of the sand washing wastewater is collected by a temperature sensor. The fluid temperature is used to retrieve a preset temperature compensation coefficient to correct the basic concentration judgment threshold and generate a dynamic concentration judgment threshold. Step S2: The control unit compares the ultrasonic attenuation ratio with the dynamic concentration judgment threshold. When the ultrasonic attenuation ratio exceeds the dynamic concentration judgment threshold and a phase state change occurs, the control unit sends a timing control command to the pipeline valve assembly set at the diversion node of the main inlet pipeline. The vortex diversion valve and the sedimentation diversion valve are controlled to make inverse proportional complementary linear adjustment of the opening within 10s to 15s. The diversion and pressure relief pipeline connected in parallel with the main inlet pipeline is opened to construct a hydraulic parallel topology and reduce the transient dynamic pressure fluctuation rate inside the main inlet pipeline. In step S3, the control unit dynamically adjusts the rotation frequency of the variable frequency mixer at the bottom of the inclined plate sedimentation tank and the opening of the return water diversion valve of the clean water reuse pipeline according to the type of phase state transition. When the phase state transitions to clay-dominant, the rotation frequency of the variable frequency mixer is switched to the first rotation frequency range of 45 rpm to 60 rpm to generate mechanical shear force. Simultaneously, the return water diversion valve is adjusted to guide 20% of the overflow water of the inclined plate sedimentation tank to the front-end regulating tank, and the fluid Reynolds number in the inclined plate separation zone inside the inclined plate sedimentation tank is controlled to be in a laminar flow state of 100 to 300.

[0021] Preferably, in step S2, when the diversion and pressure relief pipeline is opened and a hydraulic parallel topology is constructed, the opening degree variation curves of the vortex diversion valve and the sedimentation diversion valve are mirror-symmetrical, and the fluid pressure variation rate inside the diversion and pressure relief pipeline is controlled within a preset safe range.

[0022] Preferably, step S1 includes the following sub-steps: Step S11, using an ultrasonic transducer assembly installed inside the main water inlet pipeline to alternately emit 5MHz high-frequency pulsed ultrasonic waves and 1MHz low-frequency pulsed ultrasonic waves to the fluid, and receiving the attenuated energy signal after penetrating the fluid to calculate the ultrasonic attenuation ratio; Step S12, using a temperature sensor installed on the coaxial side of the ultrasonic transducer assembly to continuously collect the fluid temperature inside the main water inlet pipeline.

[0023] Preferably, in step S3, the control of the first rotation frequency range includes the following sub-steps: Step S31, when the control unit determines that the phase state transition is a clay-dominant phase transition and the ultrasonic attenuation ratio is greater than or equal to the preset second preset threshold of 2.8 for three consecutive times, the control unit outputs a speed change command; Step S32, the variable frequency mixer responds to the speed change command and adjusts the rotation frequency to the first rotation frequency range of 45 rpm to 60 rpm.

[0024] Preferably, before step S1, the sand washing wastewater is sequentially introduced into the coarse sand collection unit and the fine sand recovery unit for coarse and fine mud sedimentation and separation. The separated slurry is introduced into the front-end equalization tank for mixing and then pumped into the main inlet pipeline using a fluid supply pump.

[0025] Preferably, in step S3, a settling inclined plate is arranged inside the inclined plate separation zone, the flow velocity of the fluid in the flow channel formed by the settling inclined plate is 0.02m / s to 0.05m / s, and after the variable frequency mixer has finished operating in the first rotational frequency range, the rotational frequency is reduced to 10rpm to 15rpm.

[0026] Preferably, in step S3, when adjusting the opening of the return water diversion valve, the valve opening of the return water diversion valve inside the clean water reuse pipeline is controlled to be 20% to 40%, and the overflow water from the inclined plate sedimentation tank is introduced into the front-end regulating tank through the return water diversion valve.

[0027] Preferably, after step S3, the sedimented sludge at the bottom of the inclined plate sedimentation tank is pumped to a filter press for dewatering treatment, the solid phase sludge cake is separated, and the resulting filter press filtrate is returned to the front-end equalization tank.

[0028] Preferably, when the phase transition is a phase transition to micro-sand-dominant phase transition and the ultrasonic attenuation ratio is less than or equal to 1.2, the control unit controls the vortex diversion valve to be fully open to 100% and controls the sedimentation diversion valve to be fully closed to 0%, so as to open the diversion and pressure relief pipeline and maintain the mud flow layer interface at the bottom of the inclined plate sedimentation tank within the preset height range.

[0029] Example 1: In a continuously operating sand washing wastewater solid-liquid separation and resource comprehensive utilization site, the solid particle gradation inside the main inlet pipeline undergoes non-stationary distortion due to random movement of the sand-making mining face. When the high-plasticity clay component suddenly increases, the gravity sedimentation process with a fixed residence time window cannot effectively settle ultrafine sludge, causing fine sludge to overflow into the clean water reuse network, wearing down downstream nozzles. When the coarse-particle micro-sand component suddenly increases, the solid phase rapidly accumulates at the bottom of the sedimentation tank, forming a dense sludge layer, causing the sludge scraping mechanism to overload and trip, resulting in hydrodynamic blockage of the sludge conveying pipeline. This sedimentation imbalance and pipeline boundary layer erosion caused by transient changes in solid phase gradation bring about control challenges during the steady-state operation of the solid-liquid separation system. The method claimed in this invention controls the flow of sand washing wastewater through the inlet main pipeline. A fluid supply pump drives the sand washing wastewater through the inlet main pipeline at a flow rate of 1.5 m / s to 1.8 m / s to prevent the solid particles from stratifying and settling due to gravity. An ultrasonic transducer assembly installed inside the inlet main pipeline alternately emits 5 MHz high-frequency pulsed ultrasonic waves and 1 MHz low-frequency pulsed ultrasonic waves, and receives the attenuated energy signal after penetrating the fluid to calculate the ultrasonic attenuation ratio. Simultaneously, a temperature sensor continuously collects the fluid temperature inside the inlet main pipeline, and uses the fluid temperature to adjust a preset temperature compensation coefficient to correct the basic concentration judgment threshold to obtain the dynamic concentration judgment threshold. The ultrasonic attenuation ratio is calculated according to the formula... The calculation shows that, The ultrasonic attenuation ratio, The energy attenuation coefficient of the fluid to a 5MHz high-frequency ultrasound wave. The energy attenuation coefficient of the fluid to 1MHz low-frequency ultrasound is defined as follows: Specifically, the baseline concentration threshold is a dimensionless constant pre-measured at a standard water temperature of 20℃ and stored in the control unit's memory, with an initial value of 2.0. The temperature compensation coefficient is retrieved through a temperature-viscosity acoustic correction matrix preset in the control unit. This matrix divides the fluid temperature into multiple stepped ranges. When the fluid temperature is between 5℃ and 15℃, the retrieved temperature compensation coefficient is 0.90 to 0.95; when the fluid temperature is between 15℃ and 25℃, the temperature compensation coefficient is 0.96 to 1.04. When the fluid temperature is between 25℃ and 35℃, the temperature compensation coefficient is between 1.05 and 1.12. The control unit multiplies the basic concentration judgment threshold by the currently retrieved temperature compensation coefficient to generate a dynamic concentration judgment threshold in real time. This eliminates interference from the acoustic impedance and temperature drift of the ultrasonic propagation medium caused by changes in fluid temperature. The control unit receives the ultrasonic attenuation ratio and compares it with the dynamic concentration judgment threshold. When the ultrasonic attenuation ratio exceeds the dynamic concentration judgment threshold and a phase change occurs, the control unit sends a timing control command to the pipeline valve assembly located at the diversion node of the main inlet pipeline to control the swirling diversion valve and... The sedimentation diversion valve adjusts its opening inversely proportionally and linearly within 10 to 15 seconds, opening the diversion and pressure relief pipeline connected in parallel with the main inlet pipeline to form a hydraulic parallel topology. At this time, the opening change curves of the vortex diversion valve and the sedimentation diversion valve are mirror-symmetrical. The fluid pressure change rate inside the diversion and pressure relief pipeline is within the preset range, reducing the transient dynamic pressure change rate inside the main inlet pipeline. This eliminates the momentum mutation and hydraulic transient pressure swing caused by the sudden opening and closing of the discrete valves, maintaining the stability of the mud boundary layer at the bottom of the inclined plate sedimentation tank. During this process, the timing control command is generated by the control unit by retrieving the built-in two-dimensional time delay matrix. The delay matrix uses the rate of change of ultrasonic attenuation ratio and the pipeline pressure step value as two-dimensional input indicators. It stores a set of discrete step delay time constants, including a response delay of 0.5s to 1.2s for the swirl diverter valve and an opening delay of 0.3s to 0.8s for the sediment diverter valve. The control unit outputs timing commands containing time difference values ​​based on the matrix, so that the valve core drive motors of the swirl diverter valve and the sediment diverter valve generate microsecond-level staggered time differences, thereby accurately compensating for the asynchronous action caused by the mechanical inertia of the physical valves and the dead zone of the valve core volume, and ensuring that the opening changes of the two valves are mirror-symmetric in the time domain.

[0030] The control unit dynamically adjusts the rotation frequency of the variable frequency agitator at the bottom of the inclined plate sedimentation tank and the opening of the return water diversion valve in the clean water reuse pipeline based on the phase state transition. When the ultrasonic attenuation ratio is collected for three consecutive times greater than or equal to the preset second preset threshold of 2.8, and the phase state transition is determined to be a transition to a clay-dominant phase state, the control unit outputs a speed change command. The variable frequency agitator responds to the speed change command by adjusting its rotation frequency to a first rotation frequency range of 45 rpm to 60 rpm to generate mechanical shear force. The strong mechanical shear force field directly and physically peels off the hydration coating on the surface of fine particles, exposing their active crystal faces. Simultaneously, the return water diversion valve is adjusted to guide 20% of the overflow water from the inclined plate sedimentation tank to the front-end regulating tank, controlling the Reynolds number of the fluid in the inclined plate separation zone inside the inclined plate sedimentation tank. The flow rate is in a laminar state between 100 and 300. The inclined plate separation zone is equipped with settling inclined plates. The flow velocity of the fluid in the flow channel formed by the settling inclined plates is 0.02 m / s to 0.05 m / s. After the variable frequency mixer operates in the first rotational frequency range, the rotational frequency is reduced to 10 rpm to 15 rpm. When the ultrasonic attenuation ratio is less than or equal to 1.2, and the phase state transformation is determined to be a phase transformation to micro-sand-dominated phase, the control unit controls the cyclone diversion valve to be fully opened to 100% and controls the sedimentation diversion valve to be fully closed to 0% to open the diversion and pressure relief pipeline, guide the wastewater to gather in the multi-stage micro-cyclone group to cut off the intervention of polymer flocculant, so that the sand particles are kept in a state without polymer encapsulation and settle rapidly by strong centrifugal force, so that the mud flow layer interface at the bottom of the inclined plate sedimentation tank is maintained within the preset height range.

[0031] In adaptive phase separation control, sand washing wastewater is sequentially introduced into a coarse sand collection unit and a fine sand recovery unit before entering the main inlet pipeline for coarse and fine sand sedimentation and separation. The separated slurry is then introduced into a front-end equalization tank for mixing and pumped into the main inlet pipeline using a fluid supply pump. After solid-liquid separation in an inclined plate sedimentation tank, the sedimented sludge at the bottom of the inclined plate sedimentation tank is pumped to a filter press for dewatering to separate the solid phase sludge cake. The resulting filter press filtrate is returned to the front-end equalization tank. (The last sentence appears to be incomplete and possibly refers to a different process.) The adaptive fluid routing reprogramming based on ultrasonic attenuation ratio and the hydraulic parallel depressurization during the transition period extend the lower limit particle size of the manufactured sand recovery to 0.045mm, improve the overall fine sand recovery rate by 12%, and reduce the suspended solids concentration at the overflow outlet of the clean water reuse main pipeline to less than 50mg / L. The turbidity fluctuation variance of the reused clean water is reduced by 88%, and the slag moisture content is reduced to less than 18%. This avoids the risk of physical failure of downstream filter presses due to coarse sand abrasion of the filter cloth and pipeline blockage, and maintains the steady-state operation of the comprehensive utilization of sand washing wastewater resources.

[0032] Example 2: This experiment utilizes a hydrodynamic simulation test bench with a fully closed-loop circulation pipeline to test the adaptive steady-state response of a multi-stage physical separation and reuse process for sand washing wastewater. The test bench includes a 100mm inner diameter acrylic pipe system, an energy consumption calculation component, and a fluid supply pump with an adjustable flow rate range covering 1.0m / s to 2.0m / s. An ultrasonic transducer assembly is installed in the solid phase signal sensing section, with a fixed sampling frequency of 50Hz and an energy attenuation measurement resolution of 0.01dB. A platinum resistance temperature sensor with a measurement accuracy of 0.05℃ is embedded inside the pipe wall to capture fluctuations in the ambient temperature field. This test bench is designed to facilitate the construction of a multi-stage physical separation process in industrial applications. To address the solid phase distortion interference encountered at the mining site, high-frequency and non-periodic pressure pulses were introduced at the test fluid supply source. The amplitude fluctuation range of the pressure pulses was set to 0.05 MPa. High-plasticity bentonite particles with a median particle size of 0.005 mm were uniformly added to the circulating slurry as a clay component simulation source, and quartz microsand with a median particle size of 0.15 mm was added as a microsand component simulation source to create a non-ideal test wastewater with high-frequency, large-range slippage in solid phase gradation. Regarding the determination of the key parameter, the ultrasonic sampling pulse width, the main technical factors affecting the value include the maximum flow velocity of the characteristic slurry and the dynamic bubble scattering attenuation rate. The pulse width setting requires balancing the fluid phase. The high-resolution time-domain analysis and energy penetration depth under high scattering conditions, when the mass concentration of ultrafine clay particles in the fluid increases, causing time-domain broadening of the fundamental waveform at the transducer receiver, in order to ensure that the envelope signal acquired by the ultrasonic transducer assembly does not overlap in phase, the ultrasonic sampling pulse width converges to the lower limit of 20μs. For this specific typical working condition, the sampling pulse amplitude of this experimental group is locked at 12V. The physical setting of the above high-frequency sampling parameters directly supports the analysis of characteristic parameters. This verification experiment sets up three independent comparison sample groups. The sample group of this invention applies ultrasonic attenuation ratio adaptive shunt control and frequency conversion multi-stage stirring operation based on phase morphology. The partially missing control group one is in shunt... At the node, the complementary opening degree adjustment linear logic was removed, and a single-valve switching mode of either open or closed was adopted. In the partially missing control group 2, the variable frequency multi-stage stirring mechanism was removed in the gravity sedimentation section, and a fixed constant speed stirring of 25 rpm was maintained. In the out-of-range control group, the control flow rate and stirring rotation frequency were set outside the protection range to test the boundary effect. When the solid phase composition in the test fluid undergoes a non-stationary gradient transition from micro-sand-dominated to clay-dominated, the ultrasonic transducer assembly installed inside the main inlet pipeline continuously acquired the high and low dual-frequency energy attenuation coefficients. As the bentonite mass percentage in the slurry was adjusted to 15.3%, 55.4%, and 85.2% respectively, the key intermediate data characteristic parameter, ultrasonic attenuation ratio, was obtained. The corresponding measurements were 1.16, 2.03, and 3.14. These non-integer measurements reflect the surface scattering dissipation of highly ductile fine particles under 5 MHz ultrasound and the Rayleigh scattering ratio shift under 1 MHz ultrasound, indicating that... The numerical monotonicity of the parameter is positively correlated with the surface area of ​​the fine solid particles. The real-time output of this characteristic parameter becomes the causal trigger source for the control unit to issue the shunting logic change command. In the dynamic control cycle, the control unit also collects the transient conductivity change rate of the slurry through the conductivity sensor of the characteristic section to evaluate the negative charge encapsulation state of the surface organic matter on the surface of the fine clay particles. The specific mechanism is that the organic matter adsorbed on the particle surface will bind some of the free counterions in the fluid and change the micro-region structure of the double layer. When subjected to the overall shear flow field disturbance, the desorption and shear diffusion rate of free ions will directly cause discrete changes in the transient conductivity of the overall slurry bulk phase. That is, the magnitude of the transient conductivity change rate is positively correlated with the migration resistance of free ions in the surface double layer. The surface encapsulation and stagnation state of the clay particles can be quantitatively captured by the inverse image of the overall conductivity change rate, thereby triggering the corresponding high-frequency destabilization operation.

[0033] To determine the basis for the key numerical range defined in this invention, this experiment tested the nonlinear effect pressure oscillation at the flow velocity boundary driven by the fluid supply pump and the rotational frequency boundary of the variable frequency mixer. The test data showed that when the flow velocity was set to 1.4 m / s, which was below the protection lower limit and thus exceeded the range control point, the fluid shear torque could not overcome the gravitational precipitation resistance of the micro-sand particles, resulting in the deposition of a dense micro-sand layer with a height of 35.4 mm at the bottom of the main pipeline. This increased the pipeline fluid resistance coefficient by 42.1% and the energy consumption for slurry transportation. The flow rate was increased, but when the flow rate was set to 1.9 m / s, which was above the protection limit and exceeded the control range, the shear stress inside the pipe wall reached 15.4 Pa, causing overload and erosive wear of the throttling components such as the valve core. Furthermore, the peak dynamic pressure transient of the entire test pipeline climbed to 0.28 MPa. In contrast, when the flow rate was controlled at the three protection endpoints and the median point of 1.5 m / s, 1.65 m / s, and 1.8 m / s, the solid particles remained in a long-term suspended, non-settling state in the flow channel, and the frictional stress on the pipe wall was significantly reduced. Within the preset range of 4.2 Pa to 6.8 Pa, in the process of transitioning to a clay-dominant phase, when the rotation frequency of the variable frequency mixer is set to 35 rpm, which is below the lower limit of protection, the shear energy field strength is insufficient to peel off the hydration film layer on the surface of fine clay. Due to the lack of exposed active crystal faces on the particle surface, the fine clay particles cause the overall mud interface settling rate to drop to 0.12 mm / s. However, when the rotation frequency is set to 70 rpm, which is above the upper limit of protection, due to the excessive mechanical kinetic energy applied, the local shear rate generated around the mixing blades exceeds the critical fracture toughness of the polymer flocs, and the formed dense flocs undergo nonlinear secondary fragmentation, resulting in an increase in the mass concentration of suspended solids in the gravity sedimentation tank overflow to 145.2 mg / L. In the rotation frequency range of 45 rpm, 52 rpm, and 60 rpm set in the sample group of this invention, the hydration coating was removed, and the median particle size of the flocs expanded to 0.38 mm. This determines the process parameter boundary for which this invention is claimed.

[0034] After 100 hours of continuous phase disturbance pressure testing, the final precipitate properties and reuse index data of each sample group showed that, due to the application of ultrasonic phase identification and complementary linear pressure relief and diversion in the pipeline, the average suspended solids concentration at the overflow outlet of the sample group of this invention was 22.4 mg / L during the test period of fluid phase change. The suspended solids concentration at the overflow outlet of the clean water in the clean water reuse main pipeline was less than 50 mg / L, the turbidity fluctuation variance of the reused clean water was reduced to 4.3, and the final moisture content of the filter press solid cake remained at 16.4% to 17.8%. In contrast, the partial missing control group, due to the lack of inverse proportional opening mirror control, generated an amplitude of 0 in the pipeline at the moment of forced opening and closing of a single valve. A 45MPa water hammer transient shock wave transmitted its momentum to the bottom of the inclined plate sedimentation tank, disturbing the existing settling layer and causing fine sludge to be swept up. This resulted in a change in the suspended solids concentration of the overflow water to 245.6 mg / L, causing sludge pollution in the clear water network. In contrast, the partially missing control group 2, lacking a stepped mechanical shear energy field to remove the hydration film, could not break down the charge shielding barrier between fine clay particles. This led to a large area of ​​mud-running phase flow inside the gravity laminar settling channel, with the final overflow water turbidity variance reaching 48.6. The above comparative data show that the adaptive diversion valve regulation topology and the multi-stage stirring shear process, by providing gradation input and a stable hydraulic laminar flow boundary, generate solid-liquid physical separation and comprehensive resource recycling efficiency.

[0035] Example 3: This example combines Figures 1 to 2 This document describes a multi-stage physical separation and reuse process for sand washing wastewater, such as... Figure 1 As shown, the first stage is water inlet control, which includes the fluid pump controlling the sand washing wastewater to pass through the main pipeline, and then entering the sensing module. This module deploys ultrasonic transducer components and temperature sensors. The data flows from here to the next node to execute threshold generation and temperature coefficient correction to determine the dynamic judgment threshold. After that, the instruction proceeds to the logic control stage. The control unit compares the over-limit and issues instructions. The above instructions trigger the node to the left to perform hydraulic topology adjustment. A hydraulic parallel topology is constructed through the diversion valve. This flow direction transitions downward to the phase state adjustment node. The overflow is guided by the clay phase control mixer. Finally, the structure converges to the laminar flow control terminal node to maintain the Reynolds number in the separation zone as laminar.

[0036] like Figure 2As shown, the initial trigger node is the inlet main pipeline for sand washing wastewater. Under the condition that the ultrasonic attenuation ratio exceeds the dynamic concentration judgment threshold, the system enters the core execution module, which opens the diversion and pressure relief pipeline to construct a hydraulic parallel topology. Two state evolution branches are drawn downwards in parallel from this core module. The left branch triggers a flow direction change to the clay-dominated phase state when the ultrasonic attenuation ratio is greater than or equal to 2.8 three times consecutively. After completing the first rotation frequency range, it flows to the variable frequency mixer to reduce to a low rotation frequency. Under the specific condition that the characteristic parameter change crosses the threshold and triggers a phase state change, this downward path backtracks to the core module for opening the diversion and pressure relief pipeline to construct the hydraulic parallel topology. The right branch triggers a flow direction change to the micro-sand-dominated phase state when the ultrasonic attenuation ratio is less than or equal to 1.2. Similarly, under the specific condition that the characteristic parameter change crosses the threshold and triggers a phase state change, this right downward path backtracks to the core module for opening the diversion and pressure relief pipeline to construct the hydraulic parallel topology.

[0037] Example 4: When sand washing wastewater flows through the main inlet pipeline equipped with a solid phase detection section, and the solid particle gradation inside the main inlet pipeline undergoes a non-stationary abrupt change due to the movement of the sand making and mining face, the sudden increase in fine mud component leads to the failure state of ultrafine solid particles being carried away by the overflow mud in the gravity sedimentation tank with a fixed residence time window, or the sudden increase in coarse particle micro-sand component leads to the rapid accumulation of solid phase at the bottom of the sedimentation tank and increases the resistance torque of the sludge scraping mechanism. This imbalance of two-phase sedimentation equilibrium and the shearing failure of the pipe wall boundary layer caused by the transient slippage of the solid phase distribution index result in the risk of local embolism in the fluid dynamics transport of the multi-stage physical separation system.

[0038] A fluid supply pump drives the sand washing wastewater through the inlet main pipeline at a flow rate of 1.5 m / s to 1.8 m / s. An ultrasonic transducer assembly installed inside the inlet main pipeline alternately emits 5 MHz high-frequency pulsed ultrasonic waves and 1 MHz low-frequency pulsed ultrasonic waves, and receives the attenuated energy signals after penetrating the fluid. The control unit acquires the attenuated energy signals via a data bus to calculate the ultrasonic attenuation ratio. Simultaneously, a temperature sensor continuously collects the fluid temperature inside the inlet main pipeline. Using the fluid temperature, a preset temperature compensation coefficient is used to correct the baseline concentration threshold, thereby calculating the dynamic concentration threshold. The ultrasonic attenuation ratio is calculated based on a mathematical expression. It is confirmed that, among them, The ultrasonic attenuation ratio, The energy attenuation coefficient of a 5MHz high-frequency pulsed ultrasound. The energy attenuation coefficient of a 1MHz low-frequency pulsed ultrasound is used. When the ultrasound attenuation ratio exceeds the dynamic concentration threshold and a phase change occurs, the control unit sends a timing control command to the pipeline valve assembly located at the diversion node of the main inlet water pipeline. A hardware timer is activated to generate a 100ms control window. Within each control window, the feedback opening values ​​of the vortex diversion valve and the sedimentation diversion valve are read. The vortex diversion valve and the sedimentation diversion valve are controlled to perform inverse proportional complementary linear adjustment of their openings within 10s to 15s with a fixed step size of 0.83%. The diversion and pressure relief pipeline connected in parallel with the main inlet water pipeline is opened to form a hydraulic parallel topology, making the opening change curves of the vortex diversion valve and the sedimentation diversion valve mirror symmetrical. This limits the fluid pressure fluctuation rate inside the diversion and pressure relief pipeline to within a preset safe range, and reduces the transient dynamic pressure fluctuation rate inside the main inlet water pipeline. To reduce the instantaneous momentum change during pipeline switching and maintain the stability of the mud blanket boundary layer at the bottom of the inclined plate sedimentation tank, the microprocessor has built-in boundary saturation cutoff and time step adaptive matching logic in the linear adjustment software control algorithm. When the total action duration is set to the median point of 12s, a total of 120 control cycles are executed within a 100ms control window. A single step change of 0.83% exactly achieves 120 × 0.83% full-stroke valve switching. When the operating condition requires the total action duration to slide between 10s and 15s, the control unit dynamically fine-tunes the refresh interval of the single step action through the opening closed-loop feedback, or automatically triggers hardware register saturation cutoff when the opening reaches 100% and 0% physical limits in advance, terminating the pulse output within the subsequent control window. This ensures the linear complementary conservation of the total cross-sectional flow area and eliminates the cumulative error of the mathematical model boundary.

[0039] The control unit dynamically adjusts the rotation frequency of the variable frequency agitator at the bottom of the inclined plate sedimentation tank and the opening of the return water diversion valve in the clean water reuse pipeline according to the type of phase state transition. When the collected ultrasonic attenuation ratio is greater than or equal to the second preset threshold of 2.8 for three consecutive times, and it is determined that the phase state has changed to a clay-dominant phase state, the control unit sends a speed adjustment pulse to the variable frequency drive of the variable frequency agitator, adjusting the rotation frequency of the variable frequency agitator to the first rotation frequency range of 45 rpm to 60 rpm to generate hydromechanical shear force. The hydromechanical shear force breaks the hydration coating on the surface of fine particles and exposes the active crystal surface of the solid phase. Simultaneously, the return water diversion valve is adjusted to guide 20% of the overflow water from the inclined plate sedimentation tank to the front-end regulating tank. When the sludge interface meter installed at the bottom of the sedimentation tank measures that the solid-water settling interface change rate exceeds the low-speed settling threshold of 0.15 mm / s and is stable at 0.35 mm / s for three consecutive sampling points, the control unit controls the return water diversion valve. At the same time, the control unit linearly adjusts the rotation frequency of the variable frequency mixer to a second rotation frequency range of 10 rpm to 15 rpm within 2 minutes to establish a low shear flow field. The Reynolds number of the fluid in the inclined plate separation zone inside the inclined plate sedimentation tank is controlled to be in a laminar flow state of 100 to 300. The inclined plate separation zone is equipped with settling inclined plates. The flow velocity of the fluid in the flow channel formed by the settling inclined plates is 0.02 m / s to 0.05 m / s. The fine clay phase with exposed active crystal faces collides and agglomerates into dense solid flocs in the low shear flow field. Without changing the physical pipeline, the lower limit particle size of the manufactured sand recovery is adjusted to 0.045 mm, the overall fine sand recovery rate changes by 12%, the suspended solids concentration of the clear water overflow outlet of the inclined plate sedimentation tank is kept below 50 mg / L, the slag moisture content is kept below 18%, the mud and sand plugging and wear fault of the filter cloth of the downstream filter press is eliminated, and the sand washing wastewater resource comprehensive utilization pipeline network is maintained.

[0040] Example 5: When the inlet main pipeline experiences wall wear and boundary distortion due to the initial on-site deployment of a multi-stage physical separation process or continuous fluid scouring, the initial received energy amplitude of the ultrasonic transducer assembly installed inside the inlet main pipeline drifts in the absence of slurry flow. In the pre-baseline calibration module, before the sand washing wastewater is introduced into the inlet main pipeline, the control unit fills the pipeline with clean water with a conductivity below 10 μS / cm. The ultrasonic transducer assembly is then controlled to alternately emit 5MHz high-frequency pulsed ultrasonic waves and 1MHz low-frequency pulsed ultrasonic waves. The acquisition end continuously acquires 50 cycles of ultrasonic signals and calculates the arithmetic mean. The high-frequency clean water attenuation coefficient measured at this time is determined as the initial high-frequency reference factor. The measured low-frequency water attenuation coefficient was determined as the initial low-frequency reference factor. According to the formula The static reference attenuation ratio is calculated and stored in the controller's electrically erasable read-only memory. This is the static reference attenuation ratio. As the initial high-frequency benchmark factor, This serves as the initial low-frequency reference factor, correcting for zero-point deviations caused by errors in the physical assembly clearances of the piping.

[0041] During solid-liquid separation operations, which involve ambient temperature cyclic slippage and wear from long-term operation of the variable frequency mixer, the piezoelectric chip lattice structure of the ultrasonic transducer assembly experiences spontaneous signal drift due to mechanical fatigue. The control unit invokes a sliding time-window baseline correction module in the characteristic parameter analysis stream, setting the sliding time window to 24 hours. During non-slurry-flow periods when the solid-liquid separation equipment is intermittently shut down and the pipeline is filled with clean water, the current real-time ultrasonic attenuation ratio is automatically collected. When the attenuation ratio of the empty pipe filled with clean water is compared with the static reference attenuation ratio after five consecutive collections... When the deviation slope monotonically increases and exceeds the calibration drift threshold of 3.5%, the microprocessor calculates the ratio of the current measured value to the static reference value to determine the scaling drift compensation operator. The control unit, during the dynamic identification cycle of the introduced sand washing wastewater, collects the real-time characteristic parameter ultrasonic attenuation ratio. Multiply by the scaling drift compensation operator to implement in-situ polarity offset correction, where The real-time characteristic parameter, ultrasonic attenuation ratio, is used to suppress phase identification deviations caused by sensor aging and attenuation, maintaining the suspended solids concentration at the overflow outlet of the inclined plate sedimentation tank below 50 mg / L. In this mechanism, the 3.5% calibration drift threshold is determined by combining the inherent electroacoustic conversion efficiency of the ultrasonic sensor with the limit tolerance of random noise fluctuations in the hardware system. When the deviation slope of the empty pipe detected by the system is within 3.5%, it is mainly caused by high-frequency, high-transient mechanical vibration in the environment and weak residual fluctuations in temperature control, and does not constitute a trend-based measurement distortion. At this time, it is not necessary to activate polarity offset to prevent frequent fine-tuning and overmodulation of the controller. Once the monotonically increasing deviation exceeds the engineering safety boundary of 3.5%, it indicates that the piezoelectric chip has produced a substantial physical drift due to long-term fatigue or system thermal stress accumulation. In-situ correction is performed through the scaling drift compensation operator to ensure the zero-point accuracy of phase determination.

[0042] Example 6: When the system faces continuous operation conditions where fine mud and scale buildup on the surface of the ultrasonic transducer assembly causes monotonic distortion of the signal characteristic acoustic impedance, the fluid supply pump controls the sand washing wastewater to continuously flow through the main inlet pipe at a velocity of 1.5 m / s to 1.8 m / s. Some fine particles in the sand washing wastewater gradually deposit on the piezoelectric chip surface of the ultrasonic transducer assembly, forming a slurry film with a thickness of 12 μm to 25 μm. This causes a non-stationary step slip in the acoustic impedance at the interface between the transmitter and receiver, resulting in a decrease in the energy attenuation coefficient of the ultrasonic transducer assembly output. and In addition to changes in fluid concentration, additional energy dissipation occurs, affecting the characteristic parameter of ultrasonic attenuation ratio. A tracking deviation deviates from the actual solid particle gradation. To correct this deviation, the control unit operates an online fouling differential compensation module. The microprocessor inside the control unit uses a 1-second characteristic sampling window to collect the energy attenuation coefficient of the sand washing wastewater under normal conditions without diversion or switching, and calculates the high-frequency energy attenuation coefficient. The discrete rate of variation on the first-order time-domain difference axis is determined when the discrete rate of variation is lower than a preset static abrupt change threshold for 10 consecutive sampling periods, and the ultrasonic attenuation ratio... When the sliding arithmetic mean exhibits a continuous monotonically upward trend, the microprocessor establishes the characteristic judgment state of slurry film accumulation on the sensor surface. The microprocessor extracts the dynamic concentration judgment threshold corresponding to the current fluid temperature as the reverse boundary solution benchmark, according to the formula... Calculate the online fouling correction factor, where, This is the online fouling correction factor. This represents the currently measured real-time ultrasonic attenuation ratio. Given the current fluid temperature and known flow rate, the standard graded ultrasonic attenuation ratio reference value is preset in the controller's read-only memory matrix. The control unit outputs a command to divide the energy attenuation coefficient in subsequent acquisition cycles by the online fouling correction factor. By eliminating the nonlinear attenuation increment caused by the plasma membrane, the acoustic transmission energy level of the ultrasonic transducer assembly is restored in situ, maintaining the characteristic parameter ultrasonic attenuation ratio. Physical accuracy of fluid phase transition identification.

[0043] When the control unit clears the nonlinear decay increment and the slurry input inside the front-end equalization tank tends to stabilize, the control unit will calculate the online fouling correction coefficient. As calibration parameters, the dynamic gain distribution loop is used to update the control word of the output stage power buffer register, eliminating over-modulation or under-modulation of valve opening caused by sensor signal attenuation. Within a 10-15 second time window, the swirling and settling valves in the control pipeline valve assembly perform inverse proportional mirror linear adjustment of the opening with a fixed offset step size of 0.83%, maintaining a constant transient total flow cross-sectional area at the splitting node. This prevents the hydraulic momentum transients caused by discrete valve actions from being transmitted into the tank, and keeps the Reynolds number of the fluid in the inclined plate separation zone within the inclined plate sedimentation tank stable at 100 during the solid phase gradation slip period. Within a laminar flow range of 300, the flow velocity of the controlled fluid in the flow channel formed by the settling inclined plate is kept stable within the range of 0.02m / s to 0.05m / s. This avoids high-amplitude water hammer dynamic pressure impact caused by the malfunction of the dual valves due to slurry film recognition drift, prevents nonlinear shearing and hoisting of the fine sludge blanket at the bottom of the sedimentation tank due to flow field instability, keeps the suspended solids concentration at the final clear water overflow outlet of the clear water reuse pipeline constant below 50mg / L, controls the moisture content of the sludge discharged from the filter press to be below 18%, and maintains the long-term steady-state closed-loop operation of the multi-stage physical separation and comprehensive resource reuse system for sand washing wastewater under extreme sludge fluctuation conditions.

[0044] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit of this application and the scope of protection of this invention, and all of these forms are within the protection scope of this application.

Claims

1. A multi-stage physical separation and reuse process for sand washing wastewater, characterized in that, Includes the following steps: Step S1: The sand washing wastewater is controlled to flow through the main inlet pipe at a velocity of 1.5 m / s to 1.8 m / s using a fluid supply pump. The ultrasonic attenuation ratio of the sand washing wastewater is collected by an ultrasonic transducer assembly installed inside the main inlet pipe. At the same time, the fluid temperature of the sand washing wastewater is collected by a temperature sensor. The fluid temperature is used to retrieve a preset temperature compensation coefficient to correct the basic concentration judgment threshold and generate a dynamic concentration judgment threshold. Step S2: The control unit compares the ultrasonic attenuation ratio with the dynamic concentration judgment threshold. When the ultrasonic attenuation ratio exceeds the dynamic concentration judgment threshold and a phase state change occurs, the control unit sends a timing control command to the pipeline valve assembly set at the diversion node of the main inlet pipeline. The vortex diversion valve and the sedimentation diversion valve are controlled to make inverse proportional complementary linear adjustment of the opening within 10s to 15s. The diversion and pressure relief pipeline connected in parallel with the main inlet pipeline is opened to construct a hydraulic parallel topology and reduce the transient dynamic pressure fluctuation rate inside the main inlet pipeline. In step S3, the control unit dynamically adjusts the rotation frequency of the variable frequency mixer at the bottom of the inclined plate sedimentation tank and the opening of the return water diversion valve of the clean water reuse pipeline according to the type of phase state transition. When the phase state transitions to clay-dominant, the rotation frequency of the variable frequency mixer is switched to the first rotation frequency range of 45 rpm to 60 rpm to generate mechanical shear force. Simultaneously, the return water diversion valve is adjusted to guide 20% of the overflow water of the inclined plate sedimentation tank to the front-end regulating tank, and the fluid Reynolds number in the inclined plate separation zone inside the inclined plate sedimentation tank is controlled to be in a laminar flow state of 100 to 300.

2. The multi-stage physical separation and reuse process for sand washing wastewater according to claim 1, characterized in that, In step S2, when the diversion and pressure relief pipeline is opened and a hydraulic parallel topology is constructed, the opening degree variation curves of the vortex diversion valve and the sedimentation diversion valve are mirror-symmetric, and the fluid pressure variation rate inside the diversion and pressure relief pipeline is controlled within a preset safe range.

3. The multi-stage physical separation and reuse process for sand washing wastewater according to claim 1, characterized in that, Step S1 includes the following sub-steps: Step S11, using an ultrasonic transducer assembly installed inside the main water inlet pipeline to alternately emit 5MHz high-frequency pulsed ultrasonic waves and 1MHz low-frequency pulsed ultrasonic waves to the fluid, and receiving the attenuated energy signal after penetrating the fluid to calculate the ultrasonic attenuation ratio; Step S12, using a temperature sensor installed on the coaxial side of the ultrasonic transducer assembly to continuously collect the fluid temperature inside the main water inlet pipeline.

4. The multi-stage physical separation and reuse process for sand washing wastewater according to claim 1, characterized in that, In step S3, the control of the first rotation frequency range includes the following sub-steps: Step S31, when the control unit determines that the phase state transition is to a clay-dominant phase state transition, and the ultrasonic attenuation ratio is collected three times consecutively greater than or equal to the preset second preset threshold of 2.8, the control unit outputs a speed change command; Step S32, the variable frequency mixer responds to the speed change command and adjusts the rotation frequency to the first rotation frequency range of 45 rpm to 60 rpm.

5. The multi-stage physical separation and reuse process for sand washing wastewater according to claim 1, characterized in that, Before step S1, the sand washing wastewater is sequentially introduced into the coarse sand collection unit and the fine sand recovery unit for coarse and fine mud sedimentation and separation. The separated slurry is introduced into the front-end equalization tank for mixing and then pumped into the main inlet pipeline using a fluid supply pump.

6. The multi-stage physical separation and reuse process for sand washing wastewater according to claim 1, characterized in that, In step S3, a settling plate is configured inside the inclined plate separation zone. The flow velocity of the fluid in the flow channel formed by the settling plate is 0.02m / s to 0.05m / s. After the variable frequency mixer has completed the first rotation frequency range, the rotation frequency is reduced to 10rpm to 15rpm.

7. The multi-stage physical separation and reuse process for sand washing wastewater according to claim 1, characterized in that, In step S3, when adjusting the opening of the return water diversion valve, the valve opening of the return water diversion valve inside the clean water reuse pipeline is controlled to be 20% to 40%, and the overflow water from the inclined plate sedimentation tank is introduced into the front-end regulating tank through the return water diversion valve.

8. The multi-stage physical separation and reuse process for sand washing wastewater according to claim 1, characterized in that, After step S3, the sedimented sludge at the bottom of the inclined plate sedimentation tank is pumped to a filter press for dewatering, separating the solid sludge cake, and the resulting filter press filtrate is returned to the front-end equalization tank.

9. The multi-stage physical separation and reuse process for sand washing wastewater according to claim 1, characterized in that, When the phase transition is to a micro-sand-dominant phase transition and the ultrasonic attenuation ratio is less than or equal to 1.2, the control unit controls the vortex diversion valve to fully open to 100% and controls the sedimentation diversion valve to fully close to 0%, so as to open the diversion and pressure relief pipeline and keep the mud flow layer interface at the bottom of the inclined plate sedimentation tank within the preset height range.

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