Hydrodynamic ultrasonic synergistic cavitation micro-nano bubble foaming pipe and ultra-micro flotation column

Abstract

The application discloses a kind of micro-nano bubble foaming pipe and ultra-micro flotation column of hydraulic ultrasonic synergic cavitation, the micro-nano bubble foaming pipe includes pipe body, conical nozzle is installed in pipe body, gap is formed between nozzle outer wall and pipe body inner wall to form negative pressure suction area, a plurality of high-pressure gas inlets are provided on pipe body and communicated with negative pressure suction area, and a plurality of groups of cavitation devices are arranged along the axial direction below nozzle in pipe body;The ultra-micro flotation column includes flotation column body, flow stabilizing plate and the above-mentioned micro-nano bubble foaming pipe, the application utilizes the synergistic effect of hydraulic cavitation and ultrasonic cavitation, increases the area and pressure of negative pressure area, reduces the bubble size, strengthens turbulent disturbance, improves the probability of effective collision of particle bubble, and improves the efficiency of recovering valuable minerals in fine particles.

Description

Technical Field

[0001] This invention relates to the field of mineral flotation technology, and in particular to a micro / nano bubble generating tube and an ultra-micro flotation column with hydraulic and ultrasonic synergistic cavitation. Background Technology

[0002] Flotation is the most important method for mineral separation. Flotation mainly utilizes the difference in the repulsive force of mineral surfaces to water to separate useful minerals from gangue minerals. In a conventional flotation system, a slurry that has been reacted with reagents is fed into a flotation cell. The impeller agitates the slurry, and the gas is broken into small bubbles by shear force. Mineral particles of different sizes in the slurry continuously collide with and adhere to bubbles of different sizes, forming a temporarily stable solid-liquid-gas three-phase periphery. Then, the bubble-particle complex rises into the froth layer and is scraped out by the scraper, thus achieving flotation.

[0003] In traditional flotation systems, using large impellers to agitate the slurry in the flotation cell has many drawbacks. On the one hand, the impeller rotation speed is low, which cannot provide sufficient collision opportunities for fine particles and bubbles. On the other hand, the impeller generates a large amount of turbulence when agitating the slurry, which seriously interferes with the flotation process of fine particle-bubble aggregates and significantly increases the desorption probability of fine particles. Moreover, the diameter of bubbles generated by traditional flotation systems is usually between 80 micrometers and 200 micrometers, and the probability of collision with fine mineral particles in the slurry is extremely low, making the flotation of fine mineral particles in the slurry extremely difficult.

[0004] The most significant characteristics of fine particles are reduced particle mass and increased specific surface area. Reduced mass results in lower kinetic energy in the slurry, making it difficult for them to escape streamlines. Consequently, fine particles tend to glide along streamlines and past bubble surfaces, significantly reducing the probability of particle-bubble collisions. Increased specific surface area leads to heterogeneous aggregation of different particles to reduce their surface area, resulting in the entrainment of numerous gangue minerals and slime, thus lowering concentrate grade.

[0005] The difficulty in flotation of fine-grained minerals lies in the fact that, due to their small particle size and mass, fine-grained minerals have relatively low kinetic energy during the flotation stage. This makes it difficult for them to overcome the flow-line motion dominated by viscous forces, resulting in most fine-grained minerals simply passing over the bubble surface along the flow-line trajectory, reducing the probability of collision between fine-grained minerals and bubbles. Furthermore, the increased specific surface area leads to heterogeneous aggregation between different particles in order to reduce their specific surface area, resulting in a large amount of gangue minerals and slime entrainment, which reduces the concentrate grade. Therefore, while maintaining the original number of medium-sized bubble clusters, increasing the number of micro- and nano-bubble clusters is an effective way to increase the recovery of fine-grained minerals.

[0006] Traditional technologies mainly utilize the hydraulic cavitation effect to generate bubbles. 1) Venturi tube: At a certain flow rate, the cross-sectional area is reduced to increase the flow rate, creating a negative pressure in the high-flow-rate region (the higher the flow rate, the lower the pressure). Through self-absorption, gas from the environment is drawn into the slurry. In this process, the negative pressure region is limited, and the amount of gas drawn in is proportional to the liquid flow rate. The amount of gas adsorbed is limited, so the initial pressure in the bubble nucleation process is low, resulting in a limited number of microbubbles. However, it can meet the flotation requirements for some fine particles (particle size of 15-35 micrometers). 2) High-pressure air gun: High-pressure gas is generated by an air compressor. Relying on the self-generated high pressure, it strongly impacts the slurry flow, generating a high-intensity shearing action, dividing the gas clusters into small gas clusters. During the impact on the slurry, turbulence creates a negative pressure region. After the small gas clusters accumulate in the negative pressure region, they nucleate and generate bubbles. The negative pressure region generated in this process is limited, so the initial pressure in the nucleation process of most bubbles does not meet the requirements for forming microbubbles.

[0007] For example, the invention patent with publication number CN113941452A, entitled "A Flotation Method and Flotation System for Fine-Grained Ilmenite," describes the use of an ultrasonic cavitation device to generate micro-nano bubbles. Although ultrasonic cavitation can provide a sufficient low-pressure zone, due to the lack of external air masses, relying solely on the air masses dissolved in the slurry within the low-pressure zone, only a small number of micro-nano bubbles can be generated. At the same time, because the ultrasonic waves attenuate rapidly during propagation in the slurry, the low-pressure zone formed is mainly located around the transducer. Even if the collector solution obtained through ultrasonic cavitation is subsequently introduced into the Venturi tube through a pipeline to supplement the micro-bubbles, the two cannot achieve a synergistic effect, resulting in a limited number of micro-bubbles supplemented by the Venturi tube, which is insufficient to meet the requirements for efficient flotation of fine-grained minerals. Summary of the Invention

[0008] The first objective of this invention is to provide a micro / nano bubble generating tube with hydraulic-ultrasonic synergistic cavitation, which utilizes the synergistic effect of hydraulic cavitation and ultrasonic cavitation to increase the number of micro / nano bubbles while ensuring a certain number of medium-sized bubbles. The second objective is to provide an ultrafine flotation column that uses the aforementioned micro / nano bubble generating tube with hydraulic-ultrasonic synergistic cavitation, thereby improving the efficiency of recovering valuable minerals from fine particles by utilizing the synergy of medium-sized bubbles and micro / nano bubbles.

[0009] To achieve the first objective mentioned above, the present invention provides a micro / nano bubble foaming tube with hydraulic and ultrasonic synergistic cavitation, comprising a tube body, a conical nozzle installed inside the tube body, a gap between the outer wall of the nozzle and the inner wall of the tube body forming a negative pressure air intake zone, multiple high-pressure air inlets connected to the negative pressure air intake zone on the tube body, and multiple cavitation devices arranged axially below the nozzle on the tube body.

[0010] In this embodiment, each cavitation device includes multiple ultrasonic transducers, which are evenly arranged around the central axis of the tube body, and the working ends of the ultrasonic transducers are located inside the tube body.

[0011] In this embodiment, the working end of the ultrasonic transducer faces the outlet of the tube body, and the angle between the central axis of the working end of the ultrasonic transducer and the tangent of the circumference at the intersection of the central axis and the inner wall of the tube body is α2, and the angle with the horizontal plane is β2. The included angles α2 and β2 are 40 degrees to 50 degrees, preferably 45 degrees, and β2 is also 40 degrees to 50 degrees, preferably 45 degrees. Preferably, four ultrasonic transducers are provided, in which case the included angle between the central axes of the working ends of adjacent ultrasonic transducers is 90 degrees.

[0012] In this embodiment, two sets of cavitation devices are provided. The ultrasonic transducer frequency of the first set of cavitation devices is 75-85kHz, and the ultrasonic transducer frequency of the second set of cavitation devices is 35-45kHz.

[0013] In this embodiment, multiple high-pressure air inlets are evenly arranged around the central axis of the pipe body; the angle between the central axis of the high-pressure air inlet and the tangent of the circumference at the intersection of the central axis of the pipe body and the inner wall of the pipe body is α1, and the angle with the horizontal plane is β1. The included angle α1 is 40 degrees to 50 degrees, preferably 45 degrees, and β1 is 40 degrees to 50 degrees, preferably 45 degrees.

[0014] It is preferable to set four high-pressure air inlets, in which case the included angle between the central axes of adjacent high-pressure air inlets is 90 degrees.

[0015] In this embodiment, the nozzle includes a variable diameter inlet section, a straight pipe section, and a variable diameter outlet section in sequence from the inlet to the outlet. The variable diameter inlet section, the straight pipe section, and the variable diameter outlet section are arranged coaxially and connected end to end. The inlet end of the variable diameter inlet section is sealed to the inner wall of the pipe body. Both the variable diameter inlet section and the variable diameter outlet section are inverted cone-shaped with the inner diameter of the inlet end being larger than the inner diameter of the outlet end. The inner diameter of the inlet end of the variable diameter outlet section and the inner diameter of the straight pipe section are matched with the inner diameter of the outlet end of the variable diameter inlet section.

[0016] In this embodiment, the high-pressure air inlet is located in the area of ​​the straight pipe section of the nozzle in the negative pressure air intake zone.

[0017] To achieve the second objective mentioned above, this invention provides an ultrafine flotation column, comprising a flotation column body, a flow stabilizer plate, and the aforementioned hydraulically ultrasonically synergistically cavitated micro / nano bubble generating tube. The interior of the flotation column body is divided from top to bottom into a froth separation zone, a slurry circulation zone, and a low-flow discharge zone. A concentrate overflow collection trough is provided at the top of the flotation column body. The flow stabilizer plate is installed between the froth separation zone and the slurry circulation zone, serving as a separator between them. A feed inlet is provided at the upper part of the flotation column body, communicating with the froth separation zone. A tailflow discharge pipe is provided at the bottom of the flotation column body, communicating with the low-flow discharge zone. The invention also includes a slurry circulation device. The flotation column body has a circulation outlet and a circulation inlet. The circulation inlet communicates with the low-flow discharge zone, and the circulation outlet is higher than the circulation inlet. The slurry circulation device includes a circulation pump. The inlet of the circulation pump is connected to the circulation inlet via a pipeline, and the outlet of the circulation pump is connected to the inlet of the hydraulically ultrasonically synergistically cavitated micro / nano bubble generating tube via a pipeline. The outlet of the tube is connected to the circulation outlet via a pipeline.

[0018] Furthermore, a magnetic pipe valve is installed on the tailpipe, and holes with a diameter of 1.5 mm are evenly distributed on the flow stabilizer plate.

[0019] Due to the above structure, the present invention has the following advantages:

[0020] 1. The hydro-ultrasonic synergistic cavitation micro-nano bubble foaming tube combines the hydro-cavitation field generated by the high-pressure gas pipe and the conical nozzle with the ultrasonic cavitation field generated by the ultrasonic transducer, increasing the number of low-pressure zones and the absolute value of pressure. Under the action of strong shear and micro-jet, the high-pressure gas mass is more evenly dispersed and gathers in the negative pressure zone of the synergistic field, generating more micro-nano bubbles in a short time, effectively improving the micro-nano bubble yield per unit time.

[0021] 2. In the micro-nano bubble foaming tube of hydro-ultrasound synergistic cavitation, the high-pressure gas tube is evenly distributed, which makes the high-pressure gas cluster evenly distributed. Combined with the specific angle arrangement of the working end of the ultrasonic transducer, it promotes the slurry to rotate and move forward. This not only makes the slurry more dispersed, increases the flow rate and increases the circulation volume per unit time, but also causes the mineral particles to be thrown towards the foaming tube wall by centrifugal force, passing through the bubble area, which further increases the chance of particle-bubble collision.

[0022] 3. The angled arrangement of the two sets of ultrasonic transducers not only enables slurry swirling, but the second set of transducers can also make full use of the uniformly distributed gas clusters in the slurry after the action of the first set of transducers, providing a low-pressure zone and supplementing micro- and nano-bubbles, transforming ordinary gas clusters into medium or fine-sized bubbles, thereby ensuring a certain number of medium or fine-sized bubbles in the bubble cluster, thus achieving comprehensive recovery of valuable minerals in fine particles; this configuration can take into account the flotation of fine minerals of different particle sizes, increasing the number of micro-bubble clusters while maintaining the number of medium-sized bubble clusters, effectively improving the comprehensive recovery of fine-sized minerals.

[0023] Specifically, the high-pressure air pipe and the vortex foaming tube of the ultrasonic transducer are arranged at a 45-degree angle to the horizontal plane and at a 45-degree angle to the vertical bisector, causing the slurry to rotate and advance. On the one hand, the rotation of the slurry can disperse it more effectively and increase its flow rate, thereby increasing the amount of slurry circulated per unit time. On the other hand, due to centrifugal force during the vortex, the heavier mineral particles are thrown against the foaming tube wall. This process requires passing through a region of relatively lighter bubbles, providing additional opportunities for particle-bubble collisions. The first set of cavitation devices operates at a frequency of 75–85 kHz, and the higher frequency transducer creates a larger negative pressure zone per unit time.

[0024] The second cavitation device operates at a frequency of 35–45 kHz. The low-frequency transducer provides another opportunity for the remaining high-pressure gas masses that have not yet formed bubbles to nucleate, thus fully utilizing the gas supplied by the high-pressure gas pipe. Simultaneously, the effective working areas of the second and first cavitation devices are spaced apart along the axial direction to avoid mutual interference and reduced efficiency, while maximizing the cavitation area.

[0025] 4. By utilizing the principle of bubble nucleation, the gas pressure and radius expansion rate in the early stage of bubble nucleation are precisely controlled by increasing the number and pressure of negative pressure zones, making it easier for gas clusters to form microbubbles and optimizing the flotation conditions for fine-grained minerals.

[0026] 5. The slurry circulation device of the ultrafine flotation column includes the aforementioned hydraulic-ultrasonic synergistic cavitation micro-nano bubble generating tube. The hydraulic cavitation and ultrasonic cavitation of the micro-nano bubble generating tube produce a synergistic effect of 1+1>2, so that the slurry sprayed from the outlet of the slurry circulation device has a certain number of medium or fine particles and a large number of micro-nano bubbles, thereby significantly increasing the effective collision probability of fine mineral particles and facilitating the recovery of difficult-to-float fine mineral particles.

[0027] In summary, this device utilizes the synergistic effect of hydraulic cavitation and ultrasonic cavitation to increase the area and pressure of the negative pressure zone, reduce bubble size, enhance turbulent disturbance, and increase the probability of effective collision of particle bubbles, thereby improving the efficiency of recovering valuable minerals from fine particles. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the ultrafine flotation column of the present invention.

[0029] Figure 2 This is a schematic diagram of the structure of the micro / nano bubble foaming tube for hydraulic-ultrasonic synergistic cavitation of the present invention.

[0030] Figure 3 for Figure 2 Top view.

[0031] Figure 4 for Figure 2 A bottom view.

[0032] Figure 5 This is a schematic diagram of the tube body of the present invention.

[0033] Figure 6 for Figure 5 Cross-sectional view at point AA.

[0034] Figure 7 for Figure 5 Cross-sectional view at BB.

[0035] In the attached diagram: 1. Mixing tank; 2. Feed pump; 3. Feed inlet; 4. Flotation column body; 5. Concentrate overflow collection tank; 6. Concentrate discharge outlet; 701. Low-flow discharge zone; 702. Slurry circulation zone; 703. Foam separation zone; 8. Flow stabilizer; 9. Circulation pump; 10. Air compressor; 11. High-pressure air pipe; 12. Micro-nano bubble foaming tube for hydraulic-ultrasonic synergistic cavitation; 1201. High-pressure air inlet; 1202. Nozzle; 1203. Variable diameter inlet section; 1204. Straight pipe section; 1205. Variable diameter outlet section; 1206. Pipe body; 1207. Negative pressure suction zone; 13. Ultrasonic transducer; 1301. Working end; 14. Magnetic pipeline valve; 15. Tail discharge pipe. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0037] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0038] like Figures 2 to 7As shown, a micro / nano bubble foaming tube with hydraulic-ultrasonic synergistic cavitation includes a tube body 1206. A conical nozzle 1202 is installed inside the tube body 1206. A gap is formed between the outer wall of the nozzle 1202 and the inner wall of the tube body 1206, creating a negative pressure intake zone 1207. Four high-pressure air inlets 1201 connected to the negative pressure intake zone 1207 are provided on the tube body 1206. The high-pressure air inlets 1201 are connected to an air compressor 10 via a high-pressure air pipe 11. Multiple sets of cavitation devices are arranged axially below the nozzles 1202 on the tube body 1206. In this embodiment, two sets of cavitation devices are provided. Each set of cavitation devices includes four ultrasonic transducers 13. The multiple ultrasonic transducers 13 are evenly arranged around the central axis of the tube body 1206. The working ends of the ultrasonic transducers 13 are located inside the tube body 1206, with the working ends 1301 facing the outlet of the tube body 1206. Figure 4 and Figure 7 As shown, in this embodiment, the angle α2 between the tangent of the circumference at the intersection of the central axis of the working end 1301 of the ultrasonic transducer 13 and the inner wall of the tube 1206 is 45 degrees, and the angle β2 with the horizontal plane is 45 degrees. At this time, the angle between the central axes of adjacent working ends of ultrasonic transducers is 90 degrees. The micro-jet generated by the ultrasonic transducer passes through the edge area of ​​the slurry flow at a certain angle to form a vortex. The slurry can be transported downward in the vortex. Under the action of centrifugation, the heavier mineral particles are thrown to the tube wall, while the lighter bubbles pass through the slurry to reach the central area, so that the particles and the slurry move relative to each other, providing more collision opportunities.

[0039] Furthermore, the ultrasonic transducer 13 of the first cavitation device is set to a frequency of 75-85kHz, and the ultrasonic transducer 13 of the second cavitation device is set to a frequency of 35-45kHz. The high-frequency transducer forms a larger negative pressure zone per unit time, while the low-frequency transducer can provide another opportunity for the remaining high-pressure gas masses that have not yet formed bubbles to nucleate, thereby making full use of the gas supplied by the high-pressure gas pipe. At the same time, the effective action areas of the second cavitation device and the first cavitation device are separated along the axial direction to avoid mutual interference between the two transducers and reduce efficiency, while maximizing the cavitation area.

[0040] like Figure 7As shown, nozzle 1202, from inlet to outlet, includes a variable diameter inlet section 1203, a straight pipe section 1204, and a variable diameter outlet section 1205. These sections are coaxially arranged and connected end-to-end. The inlet end of the variable diameter inlet section 1203 is sealed to the inner wall of the pipe body 1206. The variable diameter inlet section 1203 is an inverted cone shape with an inlet inner diameter larger than the outlet inner diameter. Similarly, the variable diameter outlet section 1205 is also an inverted cone shape with an inlet inner diameter larger than the outlet inner diameter. The inlet inner diameter of the variable diameter outlet section 1205 matches the outlet inner diameter of the variable diameter inlet section 1203, and the inner diameter of the straight pipe section 1204 also matches the outlet inner diameter of the variable diameter inlet section 1203. The slurry passes sequentially through the variable diameter inlet section 1203, the straight pipe section 1204, and the outlet section 1205 of nozzle 1202. 4 and the variable diameter outlet section 1205 form a continuous action of compression-acceleration-recompression-ejection, further increasing the ejection speed of the slurry. The ejected slurry violently mixes and collides with the swirling air entering through the externally arranged high-pressure air inlet 1201. The gas is drawn into the slurry in the negative pressure suction zone, shearing to form bubbles of different sizes. The swirling air flow field further increases the intake volume, and at the same time, the contact area with the slurry along the spiral is larger, making the shearing and collision more intense. In addition, two sets of cavitation devices are axially arranged below the nozzle 1202 outlet to cavitate the gas-slurry. Thus, by utilizing the synergistic effect of hydraulic cavitation and ultrasonic cavitation, the area and pressure of the negative pressure zone are increased, the bubble size is reduced, the turbulence disturbance is enhanced, and the probability of effective collision of particle bubbles is increased, thereby improving the efficiency of recovering valuable minerals from fine particles.

[0041] like Figure 5 , 6 As shown in Figure 7, in this embodiment, four high-pressure air inlets 1201 are evenly arranged around the central axis of the pipe body 1206. The high-pressure air inlets 1201 are located in the area where the straight pipe section 1204 of the nozzle 1202 in the negative pressure suction zone is located. The angle between the central axis of the high-pressure air inlet 1201 and the tangent of the circumference at the intersection of the central axis and the inner wall of the pipe body 1206 is 45 degrees, and the angle with the horizontal plane is 45 degrees. At this time, the angle between the central axes of adjacent high-pressure air inlets 1201 is 90 degrees.

[0042] like Figure 1As shown, the present invention also includes an ultrafine flotation column, comprising a flotation column body 4, a flow stabilizer 8, and the aforementioned hydraulic-ultrasonic synergistic cavitation micro / nano bubble generating tube 12. The top of the flotation column body 4 is provided with a concentrate overflow collection trough 5. The interior of the flotation column body 4 is divided from top to bottom into a froth separation zone 703, a slurry circulation zone 702, and a low-flow discharge zone 701. The flow stabilizer 8 is installed between the froth separation zone 703 and the slurry circulation zone 702, serving as a separator between them. The flow stabilizer 8 has evenly distributed holes with a diameter of 1.5 mm. The upper part of the flotation column body 4 is provided with a feed inlet 3, and the bottom of the flotation column body 4 is provided with a tailflow discharge pipe 15. The tailflow discharge pipe 15 and the low-flow discharge zone 701 are connected. 01 is connected, and a magnetic pipe valve 14 is installed on the tail discharge pipe 15, which is connected to the central control system; it also includes a slurry circulation device, and the flotation column body 4 is provided with a circulation outlet and a circulation inlet. The circulation inlet is connected to the top of the low flow discharge zone 701, the horizontal height of the circulation outlet is higher than the horizontal height of the circulation inlet, and the circulation outlet is connected to the middle of the slurry circulation zone 702. The slurry circulation device includes a circulation pump 9, the inlet of the circulation pump 9 is connected to the circulation inlet through a pipeline, the outlet of the circulation pump 9 is connected to the inlet of the hydraulic ultrasonic synergistic cavitation micro-nano bubble foaming tube 12 through a pipeline, and the outlet of the hydraulic ultrasonic synergistic cavitation micro-nano bubble foaming tube 1206 is connected to the circulation outlet through a pipeline.

[0043] During operation, the slurry is mixed with flotation reagents in the mixing tank 1 and then enters the foam separation zone 703 through the feed pump 2 at the feed port 3;

[0044] The flow stabilizer plate 8 blocks most of the turbulent disturbances generated in the slurry circulation zone 702, thereby ensuring the relative stability of the foam separation zone 703 and reducing the desorption probability of fine particles. At the same time, the 1.5 mm holes on the flow stabilizer plate 8 can ensure that the micro-nano bubbles and fine particle composites in the slurry circulation zone 702 can rise from the slurry circulation zone to the foam separation zone 703.

[0045] The inlet of the slurry circulation pipeline is located in the middle of the low-flow discharge zone 701. The slurry enters the pipeline and is pumped to a certain height by the circulation pump 9, then vertically downwards into the hydraulically ultrasonically synergistically cavitation micro-nano bubble foaming tube 12. The slurry sequentially enters the pipe body 1206, the variable diameter inlet section 1203, the straight pipe section 1204, and the variable diameter outlet section 1205 before being ejected. It violently mixes and collides with the swirling air entering through the four high-pressure air inlets 1201 arranged in the negative pressure air intake zone 1207. The gas is in negative pressure... In the intake zone 1207, the gas is drawn into the slurry, where it is sheared to form bubbles of varying sizes. The swirling airflow increases the intake volume, and the gas contacts the slurry along a spiral path, increasing the contact area. Furthermore, the angles α1 and β1 set at the high-pressure intake port 1201 give the gas entering the pipe 1206 directionality, resulting in more intense shearing collisions between the gas and the slurry. Combined with the two sets of cavitation devices below the nozzle 1202, the mixed gas and slurry are cavitated. The ultrasonic transducer 13 rapidly vibrates back and forth along the central axis, creating alternating positive and negative pressure zones. As the slurry passes through these zones, the gas entrained within it gradually forms microjets. These microjets create intense turbulence in the slurry, increasing the collision opportunities between mineral particles and bubbles. Simultaneously, the alternating positive and negative pressure causes the gas to adhere to cavitation nuclei in the slurry (including pre-existing microbubbles, impurities, and fine-grained minerals), forming a vast number of micro- and nanobubbles. Some of these micro- and nanobubbles grow too rapidly during nucleation, resulting in large bubble radii and low internal pressure, which reduces their stability and eventually leads to their collapse. Other micro- and nanobubbles with smaller radii and higher internal pressure remain relatively stable in the slurry. These smaller bubbles provide more opportunities for collisions between bubbles and particles. Since micro- and nanobubbles are more conducive to the adhesion of fine particles, they improve the diameter distribution of the bubble cluster, thus facilitating the flotation and recovery of fine particles.

[0046] Two sets of cavitation devices are distributed in the middle and bottom of the micro-nano bubble foaming tube 12 of the hydraulic ultrasonic synergistic cavitation, forming a 90-degree angle. The angles α2 and β2 set with each ultrasonic transducer 13 in each set of cavitation devices form a swirling arrangement. The micro-jet generated by the ultrasonic transducer passes through the edge area of ​​the slurry flow at a certain angle to form a swirling flow. While the slurry is transported downward in the swirling flow, under the action of centrifugation, the heavier mineral particles are thrown to the tube wall, while the lighter bubbles pass through the slurry to reach the central area. The relative motion between the particles and the slurry further increases the probability of collision.

[0047] Finally, the slurry entering the micro-nano bubble foaming tube 12 of the hydraulic ultrasonic synergistic cavitation is returned to the flotation column body 4 through the slurry circulation outlet, further completing the collision, adhesion and flotation process of fine particles and micro-nano bubbles; minerals that have not completed mineralization and flotation in the slurry circulation zone 702 enter the low flow discharge zone 701 under the action of gravity. The low flow discharge zone 701 is equipped with a horizontally placed tail discharge pipe 15, and the tail discharge pipe 15 is equipped with a magnetic pipeline valve 14. The opening degree of the magnetic pipeline valve 14 can be controlled by the control center, thereby controlling the liquid level height of the slurry in the flotation column.

[0048] Example 1:

[0049] The test mineral was a molybdenite ore. After grinding and classification, a slurry with 85% of particles at -200 mesh was used as the feed material for the experiment. The slurry concentration was 35%, and its molybdenum grade was 0.12%. Under natural pH conditions, kerosene as a collector and No. 2 frother were added to the slurry for stirring and conditioning. The slurry in the stirred tank was then pumped into the aforementioned ultrafine flotation column for multiple flotation operations. The product in the concentrate overflow collection tank was the concentrate, while the tailings were discharged through the tailings discharge pipe as tailings. The corresponding reagent regime was 50 g / t kerosene as collector, 30 g / t No. 2 frother, and the flotation temperature was 18 degrees Celsius. As shown in Table 1, the flotation test yielded a molybdenum grade of 49.50% in the molybdenum concentrate, a recovery rate of 92.93%, a molybdenum grade of 0.0085% in the tailings, a yield of 99.77%, and a molybdenum loss of 7.07% in the tailings.

[0050] Table 1. Flotation test results of a certain molybdenite ore

[0051]

[0052] Example 2:

[0053] The test mineral was a chalcopyrite. After grinding and classification, a slurry with 80% of particles at -200 mesh was used as the feed material for the experiment. The slurry concentration was 30%, and its copper grade was 0.38%. Lime was added to the slurry to adjust the pH to 8.5. Kerosene and No. 2 frother were added to the slurry for stirring and preparation. The slurry in the stirred tank was then pumped into an ultrafine flotation column for multiple flotation operations. The product in the concentrate overflow collection tank was the concentrate, while the tailings were discharged through the tailings discharge pipe as tailings. The corresponding reagent regime was 50 g / t butyl black collector, 100 g / t butyl xanthate, and 60 g / t frother No. 2. The flotation temperature was 23 degrees Celsius. As shown in Table 2, the flotation test yielded a copper concentrate with a copper grade of 23%, a recovery rate of 90.93%, and a copper grade of 0.035% in the tailings, with a yield of 98.5% and a copper loss of 9.07% in the tailings.

[0054] Table 2. Flotation test results of a certain chalcopyrite.

[0055]

[0056] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural transformations made under the concept of the present invention using the description and drawings of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A micro / nano bubble foaming tube with hydraulic-ultrasonic synergistic cavitation, characterized in that: The device includes a tube body, inside which a conical nozzle is installed. A gap is provided between the outer wall of the nozzle and the inner wall of the tube body to form a negative pressure intake zone. The tube body has multiple high-pressure air inlets connected to the negative pressure intake zone. Below the nozzle, the tube body has multiple sets of cavitation devices arranged axially. Each set of cavitation devices includes multiple ultrasonic transducers, which are evenly distributed around the central axis of the tube body. The working ends of the ultrasonic transducers are located inside the tube body. The working ends of the ultrasonic transducers face the outlet of the tube body, and the angle between the tangent of the circumference at the intersection of the central axis of the working end of the ultrasonic transducer and the inner wall of the tube body is α2, and the angle with the horizontal plane is β2. The included angles α2 and β2 are 40 degrees to 50 degrees.

2. The micro / nano bubble foaming tube with hydraulic-ultrasonic synergistic cavitation as described in claim 1, characterized in that: Two cavitation devices are provided. The ultrasonic transducer of the first cavitation device has a frequency of 75-85 kHz, and the ultrasonic transducer of the second cavitation device has a frequency of 35-45 kHz.

3. The micro / nano bubble foaming tube with hydraulic-ultrasonic synergistic cavitation according to claim 1, characterized in that: Multiple high-pressure air inlets are evenly distributed around the central axis of the pipe body; the angle between the central axis of the high-pressure air inlet and the tangent of the circle at the intersection of the central axis of the pipe body and the inner wall of the pipe body is α1, and the angle with the horizontal plane is β1.

4. The micro / nano bubble foaming tube with hydraulic-ultrasonic synergistic cavitation according to claim 3, characterized in that: The included angle α1 is 40 degrees to 50 degrees, and β1 is 40 degrees to 50 degrees.

5. The micro / nano bubble foaming tube with hydraulic-ultrasonic synergistic cavitation according to any one of claims 1 to 4, characterized in that: The nozzle consists of a variable diameter inlet section, a straight pipe section, and a variable diameter outlet section, arranged coaxially and connected end to end. The inlet end of the variable diameter inlet section is sealed to the inner wall of the pipe body. Both the variable diameter inlet section and the variable diameter outlet section are inverted cones with an inlet end inner diameter larger than the outlet end inner diameter. The inlet end inner diameter of the variable diameter outlet section and the inner diameter of the straight pipe section are matched with the outlet end inner diameter of the variable diameter inlet section.

6. The micro / nano bubble foaming tube with hydraulic-ultrasonic synergistic cavitation according to claim 5, characterized in that: The high-pressure air inlet is located in the area where the nozzle straight pipe section is located in the negative pressure air intake zone.

7. An ultrafine flotation column, characterized in that: The flotation column body includes a flow stabilizer plate and a micro / nano bubble generating tube for hydraulic-ultrasonic synergistic cavitation as described in any one of claims 1 to 6. The interior of the flotation column body is divided into a froth separation zone, a slurry circulation zone, and a low-flow discharge zone from top to bottom. A concentrate overflow collection trough is provided at the top of the flotation column body. The flow stabilizer plate is installed between the froth separation zone and the slurry circulation zone to separate them. A feed port is provided at the top of the flotation column body and is connected to the froth separation zone. A tailflow discharge pipe is provided at the bottom of the flotation column body and is connected to the low-flow discharge zone. The flotation column body also includes a slurry circulation device. A circulation outlet and a circulation inlet are provided on the flotation column body. The circulation inlet is connected to the low-flow discharge zone. The height of the circulation outlet is higher than that of the circulation inlet. The slurry circulation device includes a circulation pump. The inlet of the circulation pump is connected to the circulation inlet through a pipeline. The outlet of the circulation pump is connected to the inlet of the micro / nano bubble generating tube body for hydraulic-ultrasonic synergistic cavitation through a pipeline. The outlet of the tube body is connected to the circulation outlet through a pipeline.

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