Mine wastewater treatment and dust falling method based on ultrasonic waves and micro-nano bubbles

Abstract

The invention discloses a mine wastewater treatment and dust fall method based on ultrasonic waves and micro-nano bubbles, and belongs to the technical field of mine wastewater treatment and dust fall. The invention discloses a mine wastewater treatment and dust falling method based on ultrasonic waves and micro-nano bubbles. The method comprises the steps of wastewater pretreatment, micro-nano bubble water preparation, wastewater deep treatment, high-pressure spraying dust falling and ultrasonic wave synergism. The problems that organic pollutants, heavy metals and acidic materials in existing mine wastewater are not efficiently purified, the fogdrop charging property in traditional spraying dust falling is insufficient, the capturing efficiency of small-particle-size dust is low, and the dust falling effect is poor are solved. Through oxidation and chemical precipitation of hydroxyl radicals, high-efficiency purification of wastewater is realized, the dosage of chemical reagents is reduced, and the environmental burden is reduced; ultrasonic waves are utilized to cooperate with micro-nano bubble breaking, the particle size and the charge property of fog drops are optimized, and the dust falling efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of mine wastewater treatment and dust reduction, and specifically to a mine wastewater treatment and dust reduction method based on ultrasonic waves and micro-nano bubbles. Background Art

[0002] The mine wastewater generated during mining has complex components, including a large amount of suspended matter (ore powder, sediment), acidic substances (such as sulfuric acid, nitric acid), organic pollutants (such as petroleum hydrocarbons, phenol compounds) and heavy metal ions (such as Pb 2+ 、Cd 2+ , Hg 2+ If these pollutants are discharged directly without effective treatment, they will seriously pollute groundwater and the surrounding ecological environment. Traditional technologies for sewage treatment usually rely on a large amount of chemical reagents, such as phosphates and sodium sulfide, which makes the cost high and easily causes secondary pollution.

[0003] At the same time, the dust generated by underground operations (especially PM2.5 and below) not only endangers the health of miners, but may also cause explosion accidents. The droplets generated by traditional atomizing nozzles are large in size (>50μm), have insufficient charge, and have low efficiency in capturing small-particle dust (<30%). They also rely on surfactants to reduce the surface tension of the liquid, making them less environmentally friendly. Summary of the invention

[0004] The purpose of the present invention is to provide a mine wastewater treatment and dust reduction method based on ultrasound and micro-nano bubbles, which can achieve efficient wastewater purification through the oxidation of hydroxyl radicals and chemical precipitation, reduce the amount of chemical reagents used, and reduce the environmental burden; use ultrasound to coordinate the rupture of micro-nano bubbles, optimize the droplet size and charge, improve the dust reduction efficiency, and solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for treating mine wastewater and reducing dust based on ultrasonic waves and micro-nano bubbles, comprising the following steps:

[0007] S1. The mine wastewater is passed through a primary purification device and a secondary purification device in sequence. The primary purification device uses a double-layer 800-mesh stainless steel ultrafilter to remove suspended solids ≥10μm, and the secondary purification device uses a backwash function to filter particles to ≤5μm;

[0008] S2. Input the pretreated wastewater and the gas in the gas cylinder into the micro-nano bubble generating device, and control the water inflow to 0.0168-0.0192m 3 / h, air intake volume is 0.00288-0.0033m 3 / h, generating micro-nano bubble water containing hydroxyl radicals;

[0009] S3, returning part of the micro-nano bubble water to the water storage tank, adding phosphate with a concentration of 1.0g / L and sodium sulfide with a concentration of 0.5g / L, oxidizing organic pollutants through hydroxyl radicals and precipitating heavy metal ions, the reaction includes:

[0010] Oxidation of organic pollutants:

[0011] CH3COOH+·OH→CH3COO - +H2O

[0012] C6H6+·OH→C6H5OH+H +

[0013] C6H5OH+·OH→C6H4(OH)2+H2O

[0014] C 10 H8+·OH→C 10 H7OH+H2O

[0015] Heavy metal ion precipitation:

[0016] Pb 2+ +2OH - →Pb(OH)2↓

[0017] 3Pb 2+ +2PO4 3- →Pb3(PO4)2↓

[0018] Pb 2+ +Na2S→PbS↓+2Na +

[0019] S4, delivering the micro-nano bubble water to the atomizing nozzle through a high-pressure water pump at a pressure of 0.5-3 MPa to generate droplets with a particle size of 10-50 μm;

[0020] S5. Generate ultrasonic waves with a frequency of 20kHz-10MHz through an ultrasonic signal generator, adjust the sound pressure to 0.5-10MPa through a power amplifier, and emit them through an acoustic wave generator to induce the rupture of micro-nano bubbles, release hydroxyl radicals to make the surface of the droplets negatively charged, and use the charge of the droplets to capture the positively charged mine dust;

[0021] S6. Based on Weber number We and critical Weber number We c The relationship between the two controls the secondary atomization process.

[0022] Preferably, the high-pressure water pump is configured to adjust the water supply pressure to control the primary atomization effect and the secondary atomization effect of the atomization nozzle;

[0023] Among them, the primary atomization effect depends on the relationship between the disturbance wavelength λ of the nozzle jet liquid column and the critical wavelength λc, and its expression is:

[0024]

[0025] Where: η is the liquid viscosity, unit is Pa·s; δ is the liquid surface tension, N / m; ρ2 is the liquid density, kg / m 3 ; β is Jeffrey coefficient, which is 0.3; ρ g is the fluid density of the airflow field, kg / m 3 ; V2' is the liquid velocity at the nozzle orifice outlet, m / s; v g is the fluid velocity in the air flow field, m / s;

[0026] According to the surface wave linear principle, λ>λ c When the liquid medium is broken into droplets under the action of gas shear, the critical wavelength λ c The smaller it is, the easier it is for atomization to occur and the smaller the droplet size.

[0027] Preferably, whether the secondary atomization effect occurs in multi-stage fragmentation depends on the Weber number We and the critical Weber number We c The relationship between We and We c The expressions are:

[0028]

[0029] Where: v f D is the droplet velocity after atomization, in m / s; i is the droplet diameter after atomization, m; v f is the droplet velocity after primary atomization, m / s.

[0030] Preferably, the We>We c It indicates that the droplets continue to break up during the secondary atomization process, and its expression is:

[0031]

[0032] Assuming that the droplet breaks into two droplets of the same size, the droplet diameter D i+1 =D i / 1.26, volume V i+1 =V i / 2, the velocity of the droplets after breaking v f+1 The expression is:

[0033]

[0034] Where: t i For droplet D iThe breaking time, in seconds.

[0035] Preferably, the formula for capturing dust by electrostatic action is:

[0036] η E =4CQ w / 3πμ g d s v0ε p

[0037] Where: η E is the dust capture efficiency of electrostatic action, unit is %; C is the Cunningham correction coefficient; μ g is the aerodynamic viscosity, Pa·S; d s is the dust particle size, m; Q w is the charge carried by the droplet per unit area, C; ε p is the dielectric constant of mineral dust, C / V·m -1 .

[0038] Preferably, the ultrasonic wave induces a violent contraction-expansion dynamic behavior of the bubbles, causing the micro-nano bubbles to burst after being affected by the ultrasonic wave, and the energy released is expressed as:

[0039]

[0040] Where: E is the energy released by bubble burst, unit is J; R max is the radius of the bubble before it bursts, m; c is the speed of sound, m / s;

[0041] The motion state of the droplets before and after breakup satisfies the law of conservation of momentum, and the motion equation is expressed as:

[0042] (m f +m b )v f =2m f+1 v f+1

[0043] Where: m f is the mass of droplets after atomization, in kg; m b is the mass of bubbles entrained in the droplets after atomization, kg; m f+1 is the mass of the droplets after breakup, kg;

[0044] The states before and after the breakup also satisfy the law of conservation of energy. The energy relationship between the droplets after the atomization is broken due to the rupture of bubbles during the movement is expressed as:

[0045]

[0046] Where: E otherIndicates energy other than kinetic energy, unit J;

[0047] The energy released by the collapse of micro-nano bubbles increases the speed of droplet breakage in the secondary atomization process, and after multiple breakages, We>We is still satisfied. c , in order to increase the number of multi-stage breakup times in the secondary atomization process and reduce the droplet size.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] 1. The present invention can construct an alkaline environment by utilizing micro-nano bubble water, which has the characteristics of strong oxidizing properties. The micro-nano bubble water is combined with chemical reagents to treat heavy metal ions and organic pollutants in the water body, thereby reducing the amount of chemical reagents that pollute the environment, having low cost, and greatly improving the wastewater purification level and increasing the utilization rate of underground wastewater.

[0050] 2. The present invention introduces spray dust reduction technology, changes the water supply pressure of the high-pressure water pump to control the flow rate, and then controls the atomization characteristics of the spray, indirectly controls the droplet size, enhances the dust capture effect of the droplets, and thus controls the dust removal; utilizes the strong wetting ability of micro-nano bubble water, uses micro-nano bubble water to spray dust, and enhances the spray dust reduction effect.

[0051] 3. The present invention utilizes the charge on the surface of the droplets to capture charged dust, promotes the bubble rupture in the micro-nano bubble water spray field through ultrasound, generates more hydroxyl radicals, increases the charge on the surface of the droplets, and strengthens the dust capture effect of electrostatic action; at the same time, the energy released by the rupture of the micro-nano bubbles can promote the atomization of the liquid medium, controls the ultrasonic characteristic parameters to induce the rupture of the micro-nano bubbles, optimizes the spray characteristics of the spray field, and strengthens the capture effect of the synergistic spray field on small-size dust particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic diagram of the working process of the present invention;

[0053] Figure 2 It is the overall device structure diagram of the present invention;

[0054] Figure 3 It is a connection schematic diagram of the ultrasonic generating device of the present invention;

[0055] Figure 4 It is a connection schematic diagram of the filtering device of the present invention.

[0056] In the figure: 1. gas cylinder; 2. water storage tank; 3. micro-nano bubble generating device; 4. storage tank; 5. high-pressure water pump; 6. atomizing nozzle; 7. power amplifier; 8. sound wave generator; 9. ultrasonic signal generator; 10. primary purification device; 11. secondary purification device; 12. stainless steel ultrafiltration mesh. DETAILED DESCRIPTION

[0057] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0058] In the existing technology, organic pollutants, heavy metals and acidic substances in mine wastewater have not been efficiently purified. The traditional spray dust reduction has insufficient charge on the droplets, low efficiency in capturing small-size dust, and poor dust reduction effect. To solve the above problems, please refer to Figure 1-4 , this embodiment provides the following technical solutions:

[0059] The mine wastewater is pre-stored in the water tank 2. The liquid in the water tank 2 comes from the underground water source. There is no need to build a water source transportation system at one end, which simplifies the overall device and reduces investment costs.

[0060] The mine wastewater is sequentially passed through a primary purification device 10 and a secondary purification device 11, wherein the primary purification device 10 uses a double-layer 800-mesh stainless steel ultrafiltration screen 12 to remove suspended solids and organic pollutants ≥ 10 μm, and the secondary purification device 11 filters particles below 5 μm through a backwashing function, and the liquid flowing into the micro-nano bubble generating device 3 is used to prepare micro-nano bubble water;

[0061] A pressure gauge is installed on the gas source pipeline of the micro-nano bubble generating device 3, and the gas cylinder 1 is replaceable. The type of gas in the gas cylinder 1 will affect the quality of the micro-nano bubble water produced, so that different types of micro-nano bubble water can be prepared. At the same time, the installed pressure gauge is used to monitor the gas delivery situation in real time to ensure the normal operation of the micro-nano bubble generating device;

[0062] The pretreated wastewater and the gas in the gas cylinder 1 are input into the micro-nano bubble generating device 3, and the water inflow is controlled to be 0.0168-0.0192m 3 / h, air intake volume is 0.00288-0.0033m 3 / h, generating micro-nano bubble water containing hydroxyl radicals;

[0063] A portion of the micro-nano bubble water is returned to the water storage tank 2, and phosphate with a concentration of 1.0 g / L and sodium sulfide with a concentration of 0.5 g / L are added to oxidize organic pollutants through hydroxyl free radicals and precipitate heavy metal ions. The strong oxidizing property of the micro-nano bubble water is used to oxidize organic pollutants. The reaction includes:

[0064] CH3COOH+·OH→CH3COO - +H2O

[0065] C6H6+·OH→C6H5OH+H +

[0066] C6H5OH+·OH→C6H4(OH)2+H2O

[0067] C 10 H8+·OH→C 10 H7OH+H2O

[0068] Pb 2+ +2OH - →Pb(OH)2↓

[0069] 3Pb 2+ +2PO4 3- →Pb3(PO4)2↓

[0070] Pb 2+ +Na2S→PbS↓+2Na +

[0071] H + + ·OH → H2O

[0072] The treated water source with sediment is treated and filtered again by the primary purification device 10, the secondary purification device 11 and the 800-mesh stainless steel ultrafiltration screen 12, and then flows into the micro-nano bubble generating device 3 to prepare micro-nano bubble water;

[0073] The prepared micro-nano bubble water is output to the storage box 4. After the storage box 4 is full, the high-pressure water pump 5 is started and the valve is adjusted to make the water supply pressure 0.5-3MPa and the water consumption flow rate 0.0105-0.021m 3 / h, transported to the atomizing nozzle 6 to generate droplets with a particle size of 10-50μm;

[0074] When the water supply pressure of the high-pressure water pump 5 is different, the droplet velocity and particle size in the atomization field processed by the atomization nozzle will be affected. The valve and flowmeter are used to control the on-off of the water source and the flow rate entering the high-pressure water pump 5, so as to adjust the atomization characteristics in real time, improve the spray field parameters, and optimize the capture of dust particles.

[0075] Specifically, the high-pressure water pump 5 is configured to adjust the water supply pressure to control the primary atomization effect and the secondary atomization effect of the atomization nozzle 6;

[0076] Among them, the primary atomization effect depends on the relationship between the disturbance wavelength λ of the nozzle jet liquid column and the critical wavelength λc, and its expression is:

[0077]

[0078] Where: η is the liquid viscosity, unit is Pa·s; δ is the liquid surface tension, N / m; ρ2 is the liquid density, kg / m 3 ; β is Jeffrey coefficient, which is 0.3; ρ g is the fluid density of the airflow field, kg / m 3 ; V2' is the liquid velocity at the nozzle orifice outlet, m / s; v g is the fluid velocity in the air flow field, m / s;

[0079] According to the surface wave linear principle, λ>λ c When the liquid medium is broken into droplets under the action of gas shear, the critical wavelength λ c The smaller it is, the easier it is for atomization to occur and the smaller the droplet size.

[0080] Whether the secondary atomization effect will produce multi-stage fragmentation depends on the Weber number (We) and the critical Weber number (We c ) relationship, We and We c The expressions are:

[0081]

[0082] Where: v f D is the droplet velocity after atomization, in m / s; i is the droplet diameter after atomization, m; v f is the droplet velocity after primary atomization, m / s.

[0083] When We>We c It indicates that the droplets continue to break up during the secondary atomization process, and its expression is:

[0084]

[0085] Assuming that the droplet breaks into two droplets of the same size, the droplet diameter D i+1 =D i / 1.26, volume V i+1 =V i / 2, the velocity of the droplets after breaking v f+1 The expression is:

[0086]

[0087] Where: t i For droplet D i The breaking time, in seconds.

[0088] The formula for capturing dust by electrostatic action is:

[0089] η E =4CQ w / 3πμ gd s v0ε p

[0090] Where: η E is the dust capture efficiency of electrostatic action, unit is %; C is the Cunningham correction coefficient; μ g is the aerodynamic viscosity, Pa·S; d s is the dust particle size, m; Q w is the charge carried by the droplet per unit area, C; ε p is the dielectric constant of mineral dust, C / V·m -1 .

[0091] After the device is running, observe the flow values ​​in the water supply pipeline of the micro-nano bubble generating device 3 and the water supply pipeline of the high-pressure water pump 5, adjust the valve to make the two readings consistent, ensure that the flow rate of micro-nano bubble water flowing out of the micro-nano bubble water storage tank 4 is consistent with the spraying consumption, and ensure that the micro-nano bubble water is uninterrupted;

[0092] The ultrasonic signal generator 9 is connected to a power source, and is connected to a power amplifier 7 and a sound wave generator 8 in sequence, and is installed above the high-pressure water pump 5. When droplets are sprayed out of the atomizing nozzle, ultrasonic waves are transmitted toward the direction of the spray field;

[0093] Ultrasonic waves with a frequency of 20kHz-10MHz are generated by an ultrasonic signal generator 9, and the sound pressure is adjusted to 0.5-10MPa by a power amplifier 7, with a pulse width between a few microseconds and a few milliseconds, and a pulse repetition frequency between 1Hz and 10kHz, and are emitted by an acoustic wave generator 8 to induce the rupture of micro-nano bubbles, release hydroxyl radicals to make the surface of the droplets negatively charged, and use the charge of the droplets to capture the positively charged mine dust;

[0094] At the same time, ultrasound can cause small-size dust particles to agglomerate. The new agglomerates formed will increase the wetting effect of droplets on dust in the dust fall field, making the agglomerates easier to settle.

[0095] Ultrasonic waves induce the bubbles to undergo a violent contraction-expansion dynamic behavior, causing the micro-nano bubbles to burst after being affected by ultrasonic waves. The energy released is expressed as:

[0096]

[0097] Where: E is the energy released by bubble burst, unit is J; R max is the radius of the bubble before it bursts, m; c is the speed of sound, m / s;

[0098] The motion state of the droplets before and after breakup satisfies the law of conservation of momentum, and the motion equation is expressed as:

[0099] (m f +m b )vf =2m f+1 v f+1

[0100] Where: m f is the mass of droplets after atomization, in kg; m b is the mass of bubbles entrained in the droplets after atomization, kg; m f+1 is the mass of the droplets after breakup, kg;

[0101] The states before and after the breakup also satisfy the law of conservation of energy. The energy relationship between the droplets after the atomization is broken due to the rupture of bubbles during the movement is expressed as:

[0102]

[0103] Where: E other Indicates energy other than kinetic energy, unit J;

[0104] The energy released by the collapse of micro-nano bubbles increases the speed of droplet breakage in the secondary atomization process, and after multiple breakages, We>We is still satisfied. c , in order to increase the number of multi-stage breakup times in the secondary atomization process and reduce the droplet size.

[0105] The energy released by the rupture of micro-nano bubbles can increase the speed of droplet movement, enhance the disturbance effect of wind flow field on the breakup and atomization of liquid medium, promote the atomization of continuous medium, optimize the characteristics of spray field, and thus improve the dust reduction effect.

[0106] Working principle: First, the mine wastewater is purified to remove suspended matter, acidic substances, organic pollutants and heavy metal ions; the purified water is mixed with gas to generate micro-nano bubble water rich in hydroxyl radicals. This water has strong oxidizing and alkaline environment construction capabilities, which helps to further treat harmful substances; the micro-nano bubble water is transported at high pressure and formed into fine droplets through an atomizing nozzle to increase the chance of contact with dust; ultrasonic waves induce bubble rupture, causing the micro-nano bubbles in the droplets to rupture, releasing more hydroxyl radicals and increasing the charge of the droplets, thereby enhancing the electrostatic dust capture effect, and the energy released during the rupture process can make the droplets finer and improve the dust reduction efficiency.

[0107] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0108] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that many changes, modifications, substitutions and alterations may be made to the embodiments without departing from the principles and spirit of the invention.

Claims

1. A mine wastewater treatment and dust reduction method based on ultrasound and micro-nano bubbles, characterized in that: The following steps are involved: S1, passing the mine wastewater through a primary purification device (10) and a secondary purification device (11) in sequence, wherein the primary purification device (10) uses a double-layer 800-mesh stainless steel ultrafilter (12) to remove suspended matter ≥10 μm, and the secondary purification device (11) filters the particulate matter to ≤5 μm through a backwashing function; S2. The pretreated wastewater and the gas in the gas cylinder (1) are input into the micro-nano bubble generating device (3), and the water inflow is controlled to be 0.0168-0.0192m 3 / h, air intake volume is 0.00288-0.0033m 3 / h, generating micro-nano bubble water containing hydroxyl radicals; S3, returning part of the micro-nano bubble water to the water storage tank (2), adding phosphate with a concentration of 1.0 g / L and sodium sulfide with a concentration of 0.5 g / L, oxidizing organic pollutants through hydroxyl free radicals and precipitating heavy metal ions, the reaction includes: Oxidation of organic pollutants: CH3COOH+·OH→CH3COO - +H2O C6H6+·OH→C6H5OH+H + C6H5OH+·OH→C6H4(OH)2+H2O C 10 H8+·OH→C 10 H7OH+H2O Heavy metal ion precipitation: Pb 2+ +2OH - →Pb(OH)2↓ 3Pb 2+ +2PO4 3- →Pb3(PO4)2↓ <h2 style=";text-align:left;direction:ltr">Pb<h2 style=";text-align:left;direction:ltr"> 2+ <h2 style=";text-align:left;direction:ltr"> +Na2S→PbS↓+2Na<h2 style=";text-align:left;direction:ltr"> + S4, delivering the micro-nano bubble water to the atomizing nozzle (6) at a pressure of 0.5-3 MPa through a high-pressure water pump (5) to generate droplets with a particle size of 10-50 μm; S5, generating ultrasonic waves with a frequency of 20kHz-10MHz through an ultrasonic signal generator (9), adjusting the sound pressure to 0.5-10MPa through a power amplifier (7), and emitting them through a sound wave generator (8), thereby inducing the rupture of micro-nano bubbles, releasing hydroxyl radicals to make the surface of the droplets negatively charged, and using the charge of the droplets to capture the positively charged mine dust; S6. Based on Weber number We and critical Weber number We c The relationship between the two controls the secondary atomization process.

2. The method for treating mine wastewater and reducing dust based on ultrasound and micro-nano bubbles according to claim 1, characterized in that: The high-pressure water pump (5) is configured to adjust the water supply pressure to control the primary atomization effect and the secondary atomization effect of the atomization nozzle (6); Among them, the primary atomization effect depends on the relationship between the disturbance wavelength λ of the nozzle jet liquid column and the critical wavelength λc, and its expression is: Where: η is the liquid viscosity, unit is Pa·s; δ is the liquid surface tension, N / m; ρ2 is the liquid density, kg / m 3 ; β is Jeffrey coefficient, which is 0.3; ρ g is the fluid density of the airflow field, kg / m 3 ; V2' is the liquid velocity at the nozzle orifice outlet, m / s; v g is the fluid velocity in the air flow field, m / s; According to the surface wave linear principle, λ>λ c When the liquid medium is broken into droplets under the action of gas shear, the critical wavelength λ c The smaller it is, the easier it is for atomization to occur and the smaller the droplet size.

3. The method for treating mine wastewater and reducing dust based on ultrasound and micro-nano bubbles according to claim 2, characterized in that: Whether the secondary atomization effect undergoes multi-stage fragmentation depends on the Weber number We and the critical Weber number We c The relationship between We and We c The expressions are: Where: v f D is the droplet velocity after atomization, in m / s; i is the droplet diameter after atomization, m; v f is the droplet velocity after primary atomization, m / s.

4. The method for treating mine wastewater and reducing dust based on ultrasound and micro-nano bubbles according to claim 3 is characterized in that: We>We c It indicates that the droplets continue to break up during the secondary atomization process, and its expression is: Assuming that the droplet breaks into two droplets of the same size, the droplet diameter D i+1 =D i / 1.26, volume V i+1 =V i / 2, the velocity of the droplets after breaking v f+1 The expression is: Where: t i For droplet D i The breaking time, in seconds.

5. The method for treating mine wastewater and reducing dust based on ultrasound and micro-nano bubbles according to claim 4, characterized in that: The formula for capturing dust by electrostatic action is: or E =4CQ w / 3am g d s v0e p Where: η E It is the dust capture efficiency of electrostatic action, unit is %; C is the Cunningham correction coefficient; μ g is the aerodynamic viscosity, Pa·S; d s is the dust particle size, m; Q w is the charge carried by the droplet per unit area, C; ε p is the dielectric constant of mineral dust, C / V·m -1 .

6. The method for treating mine wastewater and reducing dust based on ultrasound and micro-nano bubbles according to claim 5, characterized in that: The ultrasonic wave induces the violent contraction-expansion dynamic behavior of the bubbles, causing the micro-nano bubbles to burst after being affected by the ultrasonic wave. The energy released is expressed as: Where: E is the energy released by bubble burst, unit is J; R max is the radius of the bubble before it bursts, m; c is the speed of sound, m / s; The motion state of the droplets before and after breakup satisfies the law of conservation of momentum, and the motion equation is expressed as: (m f +m b )v f =2m f+1 v f+1 Where: m f is the mass of droplets after atomization, in kg; m b is the mass of bubbles entrained in the droplets after atomization, kg; m f+1 is the mass of the droplets after breakup, kg; The states before and after the breakup also satisfy the law of conservation of energy. The energy relationship between the droplets after the atomization is broken due to the rupture of bubbles during the movement is expressed as: Where: E other Indicates energy other than kinetic energy, unit J; The energy released by the collapse of micro-nano bubbles increases the speed of droplet breakage in the secondary atomization process, and after multiple breakages, We>We is still satisfied. c , in order to increase the number of multi-stage breakup times in the secondary atomization process and reduce the droplet size.

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