CN114887776B - A micro-particle classification device and method combining air flotation and inclined plate - Google Patents

Abstract

The invention discloses a micro-particle grading device and method combining air flotation and inclined plates, belonging to the technical field of powder micro-particle grading equipment. The micro-particle grading device comprises a material pretreatment system, a blocking column area, an air flotation grading system and a product collecting mechanism which are sequentially connected and obliquely connected. The material pretreatment system comprises a material uniform distributor, the blocking column area comprises a plurality of connected blocking member units, a plurality of blocking columns arranged in a staggered order are arranged on the upper side of the inner cavity of the blocking member unit, the lower side of the blocking member unit is a coarse particle channel, the lower side of the air flotation grading chamber of the air flotation grading system is connected to a bubble generator, and the product collecting mechanism is used for grading and collecting particulate materials. The invention realizes high-efficiency and multi-particle-grade grading of ultrafine powders on an inclined channel by combining the blocking column with air flotation, and at the same time, the continuous grading operation can significantly improve the production efficiency of ultrafine powders.

Description

A micro-particle classification device and method combining air flotation and inclined plate

Technical Field

The invention relates to a micro-particle classification device and method combining air flotation with an inclined plate, belonging to the technical field of powder micro-particle classification equipment.

Background technique

Microparticles are widely used in food, medicine, chemical industry, mineral processing, wastewater treatment and environmental protection. With the progress and development of industry, powder particles are required to have smaller particle size and narrower distribution range. Powder grading technology is needed to obtain high-quality powder particles.

The mechanism of flotation classification is to stir and aerate so that the micro-particle materials are fully fixed on the bubbles. The coarse particles cannot float due to their large volume. The fine particles float under the action of combining with the bubbles, thus achieving the purpose of micro-particle classification. In actual flotation production, coarse particles will combine with more micro-bubbles, resulting in a sharp decrease in the number of micro-bubbles, reducing the probability of combining fine particles with micro-bubbles, thereby reducing the accuracy and efficiency of flotation classification. Inclined plate sedimentation classification uses the shallow layer principle to sediment and classify micro-particles on an inclined plate, which can increase the sedimentation area of the classification equipment and shorten the sedimentation time of coarse particles.

Patent CN109759243B discloses a column sorting device and method for mineralization-flotation separation. Although the centrifugal force field in the mineralization chamber increases the turbulence intensity of the slurry, improves the probability of collision between particles and bubbles, and combines bubbles with coal particles, thereby strengthening the collection of fine coal particles as a whole; however, the flotation column in which the flotation classification process occurs is in a vertical direction, and there are problems such as long sedimentation time for coarse coal particles, small sedimentation area, and low probability of combination of fine particles and microbubbles, which leads to the phenomenon that coarse coal particles enter the concentrate product along with fine coal particles.

Patent CN113058751A discloses a flotation system for rare mineral separation. Although the design of the flotation mechanism not only breaks up the bubbles generated by the airflow in the flotation liquid, but also contacts the airflow at the discharge port, fully increasing the contact between the bubbles and the minerals, thereby improving the mineral flotation efficiency; however, no dispersant is added to the mineral mixture in the raw material space, resulting in insufficient overall dispersion of the mixture to be floated, and reducing the probability of combining mineral particles with bubbles, resulting in low flotation accuracy and efficiency.

The flotation classification equipment has problems such as long classification process, low classification accuracy and efficiency due to the vertical placement of the classification chamber, the lack of pretreatment of the materials to be classified, and the wide distribution range of the size of the generated microbubbles. The effective combination of flotation classification and inclined plate sedimentation classification, and the preliminary coarse and fine particle classification before the flotation classification, can give full play to the advantages of flotation and inclined plate sedimentation classification, effectively solve the problem of low probability of combination of microbubbles and fine particles, and achieve the purpose of high-precision and high-efficiency classification of powders.

Summary of the invention

In order to solve the above problems, the present invention combines the air flotation classification technology with the inclined plate classification technology to provide a micro-particle classification device combining air flotation and inclined plate, which further improves the classification accuracy and classification efficiency. The entire classification process is carried out in an inclined space, which reduces the classification time and increases the sedimentation area. The pretreatment of the material to be classified by the dispersant, the preliminary classification of the barrier column area and the design of the two-stage air distributor all improve the efficiency and accuracy of the air flotation classification.

The object of the present invention is to provide a micro-particle classification device combining air flotation and inclined plates, the device comprising a material pretreatment system, a blocking column area, an air flotation classification system and a product collection mechanism, the material pretreatment system, the blocking column area, the air flotation classification system and the product collection mechanism are sequentially connected and sealed by a bolt and nut group. The material pretreatment system, the blocking column area, the air flotation classification system and the product collection mechanism are arranged as a whole in an inclined manner.

Specifically, the material pretreatment system includes a material dispersion tank, a feed peristaltic pump, a material distributor and a magnetic stirrer. The magnetic stirrer is used to stir the material to be classified in the material dispersion tank. The material dispersion tank is connected to the material distributor via a conduit, and the feed peristaltic pump is arranged on the conduit, and the feed peristaltic pump is used to introduce the material inside the material dispersion tank into the material distributor.

Furthermore, the material distributor is in the shape of a conical terrace, the end of the material distributor with a smaller cross-sectional area is connected to the conduit, and the end of the material distributor with a larger cross-sectional area is connected to the feed port of the blocking column area.

Furthermore, a porous evenly distributed plate and an evenly distributed plate step for installing the evenly distributed plate are provided in the inner cavity of the material evenly distributed device.

Preferably, the distribution plate in the inner cavity of the material distributor is a convex curved surface with a rounded edge, which is used to stabilize the flow field distribution and is conducive to the classification of coarse and fine particles.

The uniform distribution plate is provided with notches around it, and a slot for accommodating the edge of the uniform distribution plate is provided on the step of the uniform distribution plate. The step of the uniform distribution plate corresponds to the position of the notch of the uniform distribution plate, and the notch of the uniform distribution plate is larger than the step of the uniform distribution plate. After the notch of the uniform distribution plate is inserted into the step of the uniform distribution plate and rotated at a certain angle, the edge of the uniform distribution plate is inserted into the slot of the step of the uniform distribution plate to realize the fixed installation of the uniform distribution plate.

Furthermore, the blocking column region includes a plurality of connected blocking element units. The cross section of the blocking element unit is square, a plurality of blocking columns arranged in a staggered order are arranged on the upper side of the inner cavity of the blocking element unit, and the lower side of the blocking element unit is the coarse particle channel.

Preferably, the center distance between the blocking columns in each row of the blocking element unit remains constant, and there is a certain offset between the blocking columns in each row.

Furthermore, the blocking column area is arranged obliquely, and the upper end of the blocking column area is connected to the air flotation classification system. The lower side of the air flotation classification chamber of the air flotation classification system is connected to the bubble generator.

Specifically, the air flotation classification system includes a solenoid valve, a blower, a water peristaltic pump, a bubble generator, a primary air distributor, a secondary air distributor and an air flotation classification chamber. The bubble generator is connected to the water peristaltic pump and the blower respectively, and the solenoid valve for controlling the air flow is also arranged between the blower and the bubble generator; one end of the bubble generator is also connected to the primary air distributor, and a voltmeter is arranged on the primary air distributor. The primary air distributor is connected to several secondary air distributors through corresponding bubble ducts respectively, and the secondary air distributor is connected to the lower space of the air flotation classification chamber through several fine holes, and exchanges substances with the air flotation classification chamber through the fine holes.

Furthermore, the product collecting mechanism is a Y-shaped channel. The crude product outlet is located below the front end of the Y-shaped channel, and the crude product outlet is controlled by a first ball valve.

Furthermore, the Y-shaped channel includes a Y-shaped upper channel and a Y-shaped lower channel, and the Y-shaped upper channel and the Y-shaped lower channel are distributed up and down at a certain angle in the direction perpendicular to the fluid flow. A first filter membrane is arranged at the inlet of the Y-shaped upper channel, and the first filter membrane is detachably fixed to the Y-shaped upper channel by a first clamp. The outlet of the Y-shaped upper channel is a fine product outlet, and the fine product outlet is controlled by a third ball valve.

Furthermore, a second filter membrane is provided at the inlet of the Y-shaped lower channel, and the second filter membrane is detachably fixed to the Y-shaped lower channel by a second clamp. The outlet of the Y-shaped lower channel is a finer product outlet, and the finer product outlet is controlled by a second ball valve.

Furthermore, the pore size of the first filter membrane is smaller than the pore size of the second filter membrane, and the first filter membrane and the second filter membrane are replaceable according to actual needs.

In one embodiment of the present invention, the inclination angle of the grading device is determined according to the material to be graded, and the inclination angle range may be 0-30°, so as to ensure that the graded material is smoothly collected from the product collecting mechanism.

In one embodiment of the present invention, the uniformly distributed plate material is PMMA.

In one embodiment of the present invention, the four steps of the uniform distribution plate are evenly distributed around the inner wall of the material uniform distributor, and the protruding distance of the steps of the uniform distribution plate is 2-5 mm.

In one embodiment of the present invention, the cross-sectional area of the blocking column region is slightly larger than the end of the material distributor having a larger cross-sectional area.

In one embodiment of the present invention, the cross section of the flotation classification chamber is rectangular, and the side length of the cross section of the blocking column region is slightly larger than the shorter width of the cross section of the flotation classification chamber, which is conducive to fixing a plurality of the blocking element units in the blocking column region.

In one embodiment of the present invention, the blocking element units are connected by protrusions and indentations at both ends, which is convenient for splicing. The blocking column area on the upper side of the blocking element unit can be set to 2/3-4/5 of the entire cross-sectional area, and the remaining area is the coarse particle channel.

In one embodiment of the present invention, the length of the blocking column area can be determined according to the number of the blocking column units. The number of the blocking column units can be 3-5. Too many blocking column units will cause both coarse and fine particles to be discharged from the coarse particle channel, and too few blocking column units will result in poor coarse and fine particle classification effect.

In one embodiment of the present invention, the direction in which the blower intakes air into the bubble generator is perpendicular to the flow direction of the fluid in the bubble generator, so that the fluid can cut the gas into uniform bubbles.

In one embodiment of the present invention, one end of the bubble generator connected to the primary air distributor is set as a contraction structure. When the bubble generator fluid and gas pass through the contraction structure, the flow rate increases, the pressure decreases rapidly, and the air dissolved in the water can be quickly released.

In one embodiment of the present invention, the primary air distributor is a rectangular parallelepiped with a hollow structure, and the primary air distributor is connected to the bubble generator and the plurality of bubble ducts respectively by hot melt adhesive. The secondary air distributor is composed of a plurality of uniform distribution units, and the uniform distribution units share a wall length. Each uniform distribution unit is a hollow cone, and the top of the cone of the uniform distribution unit is connected to the bubble duct by hot melt adhesive, and the bottom of the cone shares a wall surface with the flotation classification chamber. The bottom of the cone of the uniform distribution unit is evenly distributed with a plurality of fine holes, and the fine holes connect the secondary air distributor and the lower space of the flotation classification chamber.

The working principle of this micro-particle classification device is as follows:

First, the device is prepared. According to the structural characteristics of the material pretreatment system, the barrier column area, the flotation classification system and the product collection mechanism, the first filter membrane and the second filter membrane of a certain specification are installed. Then the four parts are placed at a certain angle in sequence, connected and integrated, and water leakage test and air leakage test are carried out. After the device preparation process is completed, the classification work is carried out.

At the beginning, close the feed peristaltic pump, blower and crude product outlet, mix the material to be classified with the dispersant in the material dispersion tank, stir it fully with a magnetic stirrer, and use a running water peristaltic pump to inject tap water into the classification device.

When the grading device is filled with water, the feed peristaltic pump and the blower are turned on. The material to be graded enters the material distributor under the drive of the feed peristaltic pump. Under the action of the porous distribution plate, the fluid flow of the material to be graded is uniform and stable, and the material particles are fully dispersed. The dispersed material to be graded enters the blocking column area. Due to the existence of the blocking column, the coarse material particles slide down and fall into the coarse particle channel after several collisions; the fine material particles can move around the blocking column and then pass through the blocking column area for preliminary classification of coarse and fine particles.

The gas direction inside the bubble generator is perpendicular to the fluid direction, and bubbles of uniform size are formed in the bubble generator. When passing through the contraction structure of the pipeline, the flow rate increases. According to the Bernoulli principle, the pressure at the contraction point decreases rapidly, and the air dissolved in the water is rapidly released in the form of fine bubbles. Under the action of the two-stage air distributor, a large number of fine bubbles enter the flotation classification chamber of the flotation classification system. Because the surface of the material to be classified is wrapped with the dispersant, these bubbles can not only network and combine the fine materials coming in from the coarse particle channel for further classification, but also combine with the fine particles coming out from the top of the blocking column area, so that the fine particles of the material to be classified are always kept above the classification device to avoid their sedimentation.

When the material to be classified enters the product collection mechanism, some coarse particles can directly enter the coarse product outlet. Under the action of the first filter membrane and the second filter membrane, another part of the coarse particles cannot pass through the filter membrane and settle into the coarse product outlet. The material particles smaller than the pore size of the filter membrane enter the Y-shaped channel for further classification. After the entire classification is completed, three classification particle sizes can be obtained. The coarse product outlet is used to collect coarse particles, the finer product outlet is used to collect finer particles, and the fine product outlet can collect fine particles.

Furthermore, the present invention also provides a micro-particle classification method based on a micro-particle classification device combining air flotation and an inclined plate, the method comprising the following steps:

Preparation steps: assemble the material pretreatment system, the barrier column area, the air flotation classification system and the product collection mechanism in sequence through the bolts and nuts, install the first filter membrane and the second filter membrane of a certain specification, and perform air leakage test and water leakage test.

Step 1: first close the feed peristaltic pump, the blower and the crude product outlet, use the magnetic stirrer to fully stir the material to be classified in the material dispersion tank, and use the running water peristaltic pump to inject tap water into the classification device;

Step 2: Turn on the feed peristaltic pump and the blower, and the material to be classified enters the material distributor through the drive of the feed peristaltic pump. The dispersed material to be classified undergoes preliminary classification in the barrier column area, and is further classified in the air flotation classification system using a large number of fine bubbles for the material in the coarse particle channel;

Step three: Under the action of the first filter membrane and the second filter membrane, large particle materials enter the coarse product outlet, and small particle materials enter the Y-shaped channel through the pore size of the first filter membrane or the second filter membrane, and fine particles are obtained from the fine product outlet, finer particles are obtained from the finer product outlet, and coarse particles are obtained from the coarse product outlet.

According to the method of the present invention, a dispersant is added to the material to be classified in the material dispersion tank, and the dispersant can be one or a combination of hydrophobic nanomaterials, polyethylene glycol and sodium polyacrylate.

According to the method of the present invention, the solenoid valve corresponding to the blower outlet can be opened or closed according to the indication of the pressure gauge in the primary air distributor to avoid excessive pressure due to aperture blockage.

The beneficial effects of the present invention are:

1) The entire micro-particle classification device of the present invention is placed obliquely, which solves the problems of low efficiency of vertical classification equipment and difficulty in unloading classified materials of horizontal classification equipment. Compared with vertical classification equipment, it achieves the effect of shortening the sedimentation distance of particles, shortening the sedimentation time, and greatly increasing the sedimentation area and processing volume. At the same time, by changing the size of the fluid flow rate, the solid particles are more likely to collide with the inner wall of the inclined channel under the action of their own gravity, rising fluid and other forces, and then agglomerate and slide, thereby promoting high-precision classification of coarse and fine particles;

2) The present invention fully mixes the material to be classified with the dispersant by a magnetic stirrer before feeding, thus solving the problem of agglomeration of the material to be classified due to intermolecular forces. The close combination of the dispersant and the surface of the material particles to be classified increases the hydrophobicity and aerophilicity of the material particles, improves the dispersibility of the material to be classified in the liquid medium, and ensures efficient and high-precision flotation classification of microparticles;

3) The present invention solves the problem of high turbulence intensity of the flow field caused by material feeding by setting a uniform distribution plate in the material pretreatment system, which helps to form a uniform and stable flow field state and uniformly dispersed material particles in the classification system, and promotes effective classification of powder particles in the barrier column area;

4) The present invention sets a blocking column area after the material to be classified enters the classification device and before entering the flotation classification system. The blocking columns arranged in a staggered order allow the coarse particles to slide down and settle to the coarse particle channel on the lower side after several collisions, while the fine particles can move around the columns, smoothly pass through the blocking column area and enter the flotation classification system from the upper side of the classification. The preliminary micro-particle classification solves the problem of large particle size and wide particle size range in the flotation classification process, which is conducive to the effective classification of flotation;

5) The present invention solves the problem that the dirt between the barrier columns affects the classification effect after the grading device has been running for a long time by designing the barrier column area as a splicing structure composed of several detachable barrier units, and regularly dismantling, replacing and tilting the barrier units, thereby ensuring the stability of the classification effect and extending the service life of the grading device. At the same time, according to the requirements of the graded products, the number of barrier units can be increased, thereby increasing the length of the barrier column area, thereby promoting the effective flotation classification of microparticles;

6) The present invention designs a two-stage air distributor and a contraction structure in the flotation classification system, which can effectively control the full and uniform distribution of gas, thereby generating a large number of fine bubbles, solving the problem that the coarse bubbles combine with the solid particles in the flotation classification process to form unstable and loose scum, causing the solid particles to turn and sink after the bubbles are lost, and can ensure the accuracy and efficiency of the micro-particle flotation classification results;

7) The present invention provides filter membranes of different specifications in the Y-shaped upper and lower channels of the product collection mechanism, which helps to accurately block the coarse particles outside the fine product outlet. The blocked coarse particles sink into the coarse product outlet and are discharged and collected, and are discharged from the two Y-shaped outlets at the same time, forming graded products of two particle sizes, which greatly simplifies the grading equipment that can obtain multiple particle sizes at one time;

8) The grading device of the present invention improves the dispersibility of microparticles through a material pretreatment system, preliminarily grades coarse particles in the barrier column area, further finely grades fine particles in the flotation grading system, and obtains three particles of different sizes from the product collecting mechanism, thereby solving the problems of long time consumption, low grading efficiency and unstable grading results in the existing grading process, achieving a large processing volume and continuity in the microparticle grading process, and meeting the requirements for high-precision and high-efficiency grading of powder particles.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

FIG1 is a general schematic diagram of a micro-particle classification device combining air flotation and inclined plates according to the present invention;

FIG2( a ) is a schematic cross-sectional view of a material distributor in the device of the present invention;

FIG2( b ) is a partial enlarged schematic diagram of a material distributor in the device of the present invention;

FIG3( a ) is a three-dimensional schematic diagram of a blocking member unit in the device of the present invention;

FIG3( b ) is a half-section schematic diagram of a blocking member unit in the device of the present invention;

FIG4 is an enlarged schematic diagram of a secondary air distributor in the device of the present invention;

FIG5 is a schematic diagram of the particle size distribution of raw materials in an embodiment of the present invention;

FIG6 is a schematic diagram of a microparticle classification device of Comparative Example 2 of the present invention.

Among them, 1. Material pretreatment system, 101. Material dispersion tank, 102. Feed peristaltic pump, 103. Material distributor, 1031. Distributor plate, 104. Distributor plate step, 105. Magnetic stirrer, 2. Blocking column area, 201. Blocking unit, 202. Coarse particle channel, 203. Blocking column, 204. Bolt, 205. Nut, 3. Air flotation classification system, 301. Secondary air distributor, 302. Pressure gauge, 303. Primary air distributor, 304. Bubble generator device, 305. water peristaltic pump, 306. solenoid valve, 307. blower, 308. bubble duct, 309. flotation classification chamber, 4. product collection mechanism, 401. first ball valve, 402. coarse product outlet, 403. Y-type lower channel, 404. fine product outlet, 405. second ball valve, 406. third ball valve, 407. fine product outlet, 408. Y-type upper channel, 409. first filter membrane, 410. second filter membrane, 411. first clamp, 412. second clamp.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

Embodiment 1:

This embodiment provides a micro-particle classification device combining air flotation and inclined plates, as shown in Figure 1, the device includes a material pretreatment system 1, a blocking column area 2, an air flotation classification system 3 and a product collection mechanism 4. The material pretreatment system 1, the blocking column area 2, the air flotation classification system 3 and the product collection mechanism 4 are sequentially connected and sealed by a bolt-nut group formed by bolts 204 and nuts 205.

Further, specifically, the material pretreatment system includes a material dispersion tank 101, a feed peristaltic pump 102, a material distributor 103 and a magnetic stirrer 105. The magnetic stirrer 105 is used to stir the material to be classified in the material dispersion tank 101. The material dispersion tank 101 is connected to the material distributor 103 through a conduit, and the feed peristaltic pump 102 is arranged on the conduit, and the feed peristaltic pump 102 is used to introduce the material inside the material dispersion tank 101 into the material distributor 103.

Furthermore, the material distributor 103 is in the shape of a conical terrace, the end of the material distributor 103 with a small cross-sectional area is connected to the conduit, and the end of the material distributor 103 with a large cross-sectional area is connected to the feed port of the blocking column area 2. The inner cavity of the material distributor 103 is provided with a porous distribution plate 1031 and a distribution plate step 104 for installing the distribution plate 1031.

2(a) and 2(b), the distribution plate 1031 in the inner cavity of the material distributor 103 in this embodiment is a convex curved surface with a rounded edge, which is used to stabilize the flow field distribution and facilitate the classification of coarse and fine particles. The material of the distribution plate 1031 is PMMA.

The uniform distribution plate 1031 is provided with notches around it, and a slot for accommodating the edge of the uniform distribution plate 1031 is provided on the uniform distribution plate step 401. The uniform distribution plate step 401 corresponds to the position of the notch of the uniform distribution plate 1031, and the notch of the uniform distribution plate 1031 is larger than the uniform distribution plate step 401. After the notch of the uniform distribution plate 1031 is inserted into the uniform distribution plate step 401 and rotated at a certain angle, the edge of the uniform distribution plate 1031 is inserted into the slot of the uniform distribution plate step 401, thereby realizing the fixed installation of the uniform distribution plate 1031.

Furthermore, the blocking column area 2 includes four connected blocking element units 201. The blocking element unit 201 has a square cross section, and a plurality of blocking columns 203 arranged in a staggered order are arranged on the upper side of the inner cavity of the blocking element unit 201, and a coarse particle channel 202 is provided on the lower side of the blocking element unit 201.

Furthermore, the upper end of the blocking column area 2 is connected to the air flotation classification system 3, and the air flotation classification system 3 includes a solenoid valve 306, a blower 307, a water peristaltic pump 305, a bubble generator 304, a primary air distributor 303, a secondary air distributor 301 and an air flotation classification chamber 309. The bubble generator 304 is respectively connected to the water peristaltic pump 305 and the blower 307, and a solenoid valve 306 for controlling the air flow is also arranged between the blower 307 and the bubble generator 304; one end of the bubble generator 304 is also connected to the primary air distributor 303, and a voltmeter 302 is arranged on the primary air distributor. One primary air distributor 303 is connected to several secondary air distributors 301 through corresponding bubble ducts 308, and the secondary air distributor 301 is connected to the lower space of the air flotation classification chamber 309 through several fine holes, and exchanges substances with the air flotation classification chamber 309 through the fine holes.

Furthermore, the product collecting mechanism 4 is a Y-shaped channel. The crude product outlet 402 is located below the front end of the Y-shaped channel, and the crude product outlet 402 is controlled by a first ball valve 401 .

Furthermore, the Y-shaped channel includes a Y-shaped upper channel 408 and a Y-shaped lower channel 403, and the Y-shaped upper channel 408 and the Y-shaped lower channel 403 are arranged up and down at a certain angle in the direction perpendicular to the fluid flow. A first filter membrane 409 is arranged at the inlet of the Y-shaped upper channel 408, and the first filter membrane 409 is detachably fixed to the Y-shaped upper channel 408 by a first clamp 411. The outlet of the Y-shaped upper channel 408 is a fine product outlet 407, and the fine product outlet 407 is controlled by a third ball valve 406.

Furthermore, a second filter membrane 410 is provided at the inlet of the Y-shaped lower channel 403 , and the second filter membrane 410 is detachably fixed to the Y-shaped lower channel 403 by a second clamp 412 . The outlet of the Y-shaped lower channel 403 is a finer product outlet 404 , and the finer product outlet 404 is controlled by a second ball valve 405 .

Furthermore, the four distribution plate steps 104 are distributed around the inner wall of the material distributor 103, and the protruding distance of the distribution plate steps 104 is 2 to 5 mm.

Furthermore, the cross section of the blocking column region 2 is square, and the cross-sectional area is slightly larger than the end of the material distributor 103 with a larger cross-sectional area.

Furthermore, the cross section of the air flotation classification chamber 309 is rectangular, and the side length of the cross section of the blocking column region 2 is slightly larger than the shorter width of the cross section of the air flotation classification chamber 309 , which is conducive to fixing a plurality of the blocking element units 201 in the blocking column region 2 .

Furthermore, the blocking element units 201 are connected by protrusions and indentations at both ends for easy assembly. The blocking column 203 area on the upper side of the blocking element unit 201 can be set to 2/3-4/5 of the entire cross-sectional area, and the remaining area is the coarse particle channel 202.

3( a ) and 3 ( b ), the center distance of the blocking columns 203 in each row of the blocking member unit 201 remains constant, and there is a certain offset between the blocking columns 203 in each row to keep the blocking columns 203 arranged in a staggered manner.

In one embodiment of the present invention, the length of the blocking column area 2 can be determined according to the number of the blocking column units 201. The number of the blocking column units 201 can be 3-5. Too many blocking column units 201 will cause both coarse and fine particles to be discharged from the coarse particle channel 202, and too few blocking column units 201 will result in poor coarse and fine particle classification effect.

Working principle of blocking column area 2: When fully dispersed materials to be classified enter blocking column area 2, since each layer of blocking columns 203 of blocking column unit 201 has a certain offset, in the process of materials passing through blocking column area 2, both coarse and fine particles will collide with blocking columns 203. Coarse particles settle after several collisions and slide into coarse particle channel 202, while fine particles are easy to change the direction of movement after collision and present a trajectory of running around the column, thereby classifying coarse and fine particles. Fine particles remain at the top after entering flotation classification chamber 309, while coarse particles enter the bottom of flotation classification chamber 309 from the coarse particle channel 202 at the bottom, which is convenient for further classification of the flotation classification system.

Furthermore, the direction in which the blower 307 inlet air into the bubble generator 304 is perpendicular to the flow direction of the fluid in the bubble generator 304, so that the fluid can cut the gas into uniform bubbles.

Furthermore, one end of the bubble generator 304 connected to the primary air distributor 303 is set as a contraction structure. When the fluid and gas pass through the contraction structure, the flow rate increases, the pressure decreases rapidly, and the air dissolved in the water can be quickly released.

Referring to Fig. 4, the primary air distributor 303 is a rectangular parallelepiped with a hollow structure, and the primary air distributor 303 is connected to the bubble generator 304 and the plurality of bubble ducts 308 respectively by hot melt adhesive. The secondary air distributor 301 is composed of a plurality of uniform distribution units, and the uniform distribution units share a wall length. Each uniform distribution unit is a hollow cone, and the top of the cone of the uniform distribution unit is connected to the bubble duct 308 by hot melt adhesive, and the bottom of the cone shares a wall surface with the air flotation classification chamber 309. The cone bottom of the uniform distribution unit is evenly distributed with a plurality of fine holes, and the fine holes connect the secondary air distributor 301 and the lower space of the air flotation classification chamber 309.

Working principle of the flotation classification system 3: The gas direction of the blower 307 is perpendicular to the fluid direction of the water peristaltic pump 305, and bubbles of uniform size are formed in the bubble generator 304. When passing through the pipe contraction structure, the flow rate increases. According to the Bernoulli principle, the pressure at the contraction point decreases rapidly, and the air dissolved in the water is rapidly released in the form of fine bubbles. Under the action of the two-stage air distributor, a large number of fine bubbles enter the flotation classification chamber 309 of the flotation classification system 3. Because the surface of the material to be classified is wrapped with the dispersant, these bubbles have two effects. One is that they can network and combine with the fine materials mixed in the coarse particle channel 202, so that they are suspended above the flotation classification chamber 309 for further classification; the other is that they can combine with the fine particles coming out from the blocking column area 2, so that the fine particles of the material to be classified are always kept above the classification device to avoid their sedimentation, thereby realizing the fine classification of microparticles by flotation.

Furthermore, the first filter membrane 409 and the second filter membrane 410 are replaceable according to actual needs.

The working principle of the microparticle classification device in this embodiment is as follows:

First, the device is prepared. According to the structural characteristics of the material pretreatment system 1, the barrier column area 2, the flotation classification system 3 and the product collection mechanism 4, the first filter membrane and the second filter membrane of a certain specification are installed. Then the four parts are placed at a certain angle in sequence, connected and integrated, and water leakage test and air leakage test are carried out. After the device preparation process is completed, the classification work is carried out.

At the beginning, the feed peristaltic pump 102, the blower 307 and the crude product outlet 402 are closed first, the material to be classified is mixed with the dispersant in the material dispersion tank 101, and the magnetic stirrer 105 is used to fully stir, and tap water is injected into the classification device using the flowing water peristaltic pump 305.

When the grading device is filled with water, the feed peristaltic pump 102 and the blower 307 are turned on. The material to be graded enters the material distributor 103 under the drive of the feed peristaltic pump 102. Under the action of the porous uniform distribution plate 1031, the fluid flow of the material to be graded is uniform and stable, and the material particles are fully dispersed. The dispersed material to be graded enters the blocking column area 2. Due to the existence of the blocking column 203, the coarse material particles slide down and fall into the coarse particle channel 202 after several collisions; the fine material particles can move around the blocking column 203 and then pass through the blocking column area 2 to perform preliminary classification of coarse and fine particles.

The gas direction inside the bubble generator 304 is perpendicular to the fluid direction, and bubbles of uniform size are formed in the bubble generator 304. When passing through the pipe contraction structure, the flow rate increases. According to the Bernoulli principle, the pressure at the contraction point decreases rapidly, and the air dissolved in the water is rapidly released in the form of fine bubbles. Under the action of the two-stage air distributor, a large number of fine bubbles enter the flotation classification chamber 309 of the flotation classification system 3. Because the surface of the material to be classified is wrapped with the dispersant, these bubbles can not only network and combine the fine materials coming in from the coarse particle channel 202 for further classification, but also combine with the fine particles coming out from the top of the blocking column area 2, so as to keep the fine particles of the material to be classified above the classification device to avoid their sedimentation.

When the material to be classified enters the product collection mechanism 4, some coarse particles can directly enter the coarse product outlet 402. Under the action of the first filter membrane 409 and the second filter membrane 410, another part of the coarse particles cannot pass through the filter membrane and settle into the coarse product outlet 402. Material particles smaller than the pore size of the filter membrane enter the Y-shaped channel for further classification. After the entire classification is completed, three classification particle sizes can be obtained. The coarse product outlet 402 is used to collect coarse particles, the finer product outlet 404 is used to collect finer particles, and the fine product outlet 407 can collect fine particles.

The micro-particle classification device in this embodiment was used for the test. When the median particle size of the raw material powder particles is 5.94 μm, its particle size distribution is shown in FIG5 . The selected parameters are as follows: the pore size of the first filter membrane 409 is 5 μm, the pore size of the second filter membrane 410 is 8 μm, the air volume of the blower 307 is 6-30 m ³ /h, the flow rate of the feed peristaltic pump 102 is 12 r/min-24 r/min, and the measured flow rate is 34.7 ml/min-69.3 ml/min, the flow rate of the water peristaltic pump 305 is 10 r/min-30 r/min, and the measured flow rate is 27.2 ml/min-91.5 ml/min, and the blower 307 adopts a Roots blower.

After a test, the present invention collects solid particles from the product collection system and detects that the median particle sizes of three classified products are 1.21 μm, 3.96 μm and 15.62 μm, respectively, thereby realizing multi-grade classification of powder particles combining air flotation and inclined plates, greatly improving the classification efficiency and classification accuracy.

In order to verify the classification efficiency and classification accuracy of the classification device in this embodiment, a comparative example test was also carried out.

Comparative Example 1:

When no dispersant is added to the material dispersion tank (i.e., only the material to be classified is present), the remaining device design and classification method steps are consistent with the embodiment, and the particle size of the classified product is shown in Table 1. It can be seen that a large number of fine particles are insufficiently dispersed, agglomerated and settled to the bottom of the flotation classification chamber 309, and enter the coarse product outlet 402 along with the coarse particles, resulting in a smaller median particle size of the powder particles in the coarse product, a larger particle size distribution range, and a poorer classification effect.

Table 1 Particle sizes of three classified products of Comparative Example 1

Comparative Example 2:

When there is no blocking unit in the blocking column area (i.e., a separate inclined channel area), the remaining device design and classification method steps are consistent with the embodiment, as shown in Figure 6, and the particle sizes of the classified products are shown in Table 2. It can be seen that the materials to be classified are uniformly present in the flotation classification chamber. Under the action of fine bubbles, there are many coarse particles above the classification chamber, resulting in the median particle sizes of the products collected in the upper and lower Y-shaped channels being very close, and it is impossible to achieve the requirement of obtaining three particle sizes of classified products at one time.

Table 2 Particle sizes of three classified products of Comparative Example 2

Comparative Example 3

When there is no filter membrane in the product collection system, the remaining device design and classification method steps are consistent with the embodiment. As the feed flow rate increases, the higher the overlap of the three particle size distribution ranges collected, the worse the classification effect.

Embodiment 2:

This embodiment provides a micro-particle classification method, which is applied to the micro-particle classification device combining air flotation and inclined plates described in Embodiment 1, and includes:

Preparation step: assemble the material pretreatment system 1, the blocking column area 2, the air flotation classification system 3 and the product collection mechanism 4 in sequence by means of the bolts 204 and nuts 205, install the first filter membrane 409 and the second filter membrane 410 of a certain specification, and perform air leakage test and water leakage test;

Step 1: At the beginning of the experiment, the feed peristaltic pump 102, the blower 307 and the crude product outlet 402 are first turned off, the magnetic stirrer 105 is used to fully stir the material to be classified in the material dispersion tank 101, and the water peristaltic pump 305 is used to inject tap water into the classification device;

Step 2: When the grading device is filled, the feed peristaltic pump 102 and the blower 307 are turned on, and the material to be graded is driven by the feed peristaltic pump 102 to enter the material distributor 103, and the dispersed material to be graded is initially graded in the barrier column area 2, and is further graded in the air flotation grading system 3 using a large number of fine bubbles for the material in the coarse particle channel 202;

Step three: Under the action of the first filter membrane 409 and the second filter membrane 410, large particles enter the coarse product outlet 402, and small particles enter the Y-shaped channel through the aperture of the first filter membrane 409 or the second filter membrane 410, and fine particles are obtained from the fine product outlet 407, finer particles are obtained from the finer product outlet 404, and coarse particles are obtained from the coarse product outlet 402.

According to the method of this embodiment, a dispersant is added to the material to be classified in the material dispersion tank 101, and the dispersant can be one or a combination of hydrophobic nanomaterials, polyethylene glycol and sodium polyacrylate.

According to the method of this embodiment, the solenoid valve 306 corresponding to the air outlet of the blower 307 can be opened or closed according to the indication of the pressure gauge 302 in the primary air distributor 303 to avoid excessive pressure due to aperture blockage.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A micro-particle classification device combining air flotation and inclined plates, characterized in that the device comprises a material pretreatment system (1), a blocking column area (2), an air flotation classification system (3) and a product collection mechanism (4), wherein the material pretreatment system (1), the blocking column area (2), the air flotation classification system (3) and the product collection mechanism (4) are sequentially connected and connected in an upwardly inclined manner; The material pretreatment system (1) comprises a material uniform distributor (103), wherein a porous uniform distribution plate (1031) is arranged inside the material uniform distributor (103); The blocking column area (2) comprises a plurality of connected blocking element units (201), a plurality of blocking columns (203) arranged in a staggered order are arranged on the upper side of the inner cavity of the blocking element unit (201), and a coarse particle channel (202) is provided on the lower side of the blocking element unit (201); The lower side of the air flotation classification chamber (309) of the air flotation classification system (3) is in communication with the bubble generator (304); The product collecting mechanism (4) is provided with a coarse product outlet (402), a fine product outlet (407) and a relatively fine product outlet (404); the fine product outlet (407) is located above the relatively fine product outlet (404); the coarse product outlet (402) is located below the relatively fine product outlet (404); and filter membranes are respectively provided at the front ends of the relatively fine product outlet (404) and the fine product outlet (407). 2. The micro-particle classification device combining air flotation and inclined plate according to claim 1, characterized in that the material pretreatment system comprises a material dispersion tank (101), a feed peristaltic pump (102), a material distributor (103) and a magnetic stirrer (105); The material dispersion tank (101) is connected to the material distributor (103) via a conduit, and the feed peristaltic pump (102) is arranged on the conduit; The material distributor (103) is in the shape of a conical step; the end of the material distributor (103) with a smaller cross-sectional area is connected to the conduit, and the end of the material distributor (103) with a larger cross-sectional area is connected to the feed port of the blocking column region (2); the inner cavity of the material distributor (103) is provided with a distribution plate step (104) for installing a distribution plate (1031). 3. The micro-particle classification device combining air flotation and inclined plate according to claim 2, characterized in that the air flotation classification system (3) comprises a solenoid valve (306), a blower (307), a water peristaltic pump (305), a bubble generator (304), a primary air distributor (303), a secondary air distributor (301) and an air flotation classification chamber (309); The bubble generator (304) is respectively connected to a water peristaltic pump (305) and a blower (307), and a solenoid valve (306) for controlling the air flow rate is also arranged between the blower (307) and the bubble generator (304); one end of the bubble generator (304) is also connected to the primary air distributor (303), and a pressure gauge (302) is arranged on the primary air distributor (303). The primary air distributor (303) is connected to the secondary air distributor (301) through a bubble duct (308), and the secondary air distributor (301) is connected to the lower space of the flotation classification chamber (309) through a plurality of fine holes. 4. The micro-particle classification device combining air flotation and inclined plate according to claim 3, characterized in that the product collecting mechanism (4) is a Y-shaped channel, the coarse product outlet (402) is located below the front end of the Y-shaped channel, the Y-shaped channel comprises a Y-shaped upper channel (408) and a Y-shaped lower channel (403), and the Y-shaped upper channel (408) and the Y-shaped lower channel (403) are distributed up and down at a certain angle in the direction perpendicular to the fluid flow; A first filter membrane (409) is disposed at the inlet of the Y-shaped upper channel (408), and the outlet of the Y-shaped upper channel (408) is the fine product outlet (407); a second filter membrane (410) is disposed at the inlet of the Y-shaped lower channel (403), and the outlet of the Y-shaped lower channel (403) is the relatively fine product outlet (404); The pore size of the first filter membrane (409) is smaller than the pore size of the second filter membrane (410). 5. The micro-particle classification device combining air flotation and inclined plate according to claim 2 is characterized in that the uniform distribution plate (1031) in the inner cavity of the material uniform distributor (103) is a convex curved surface with a rounded edge, and notches are provided around the uniform distribution plate (1031), and the uniform distribution plate step (104) corresponds to the position and size of the notch of the uniform distribution plate (1031). 6. The micro-particle classification device combining air flotation and inclined plate according to claim 3, characterized in that the center distance of the blocking columns (203) in each row of the blocking element unit (201) remains constant, and there is a certain offset between the blocking columns (203) in each row. 7. The micro-particle classification device combining air flotation and inclined plates according to claim 4, characterized in that the direction in which the blower (307) feeds air into the bubble generator (304) is perpendicular to the flow direction of the fluid in the bubble generator (304); One end of the bubble generator (304) connected to the primary air distributor (303) is configured as a contraction structure; One end of the primary air distributor (303) is connected to the pressure gauge (302). 8. A micro-particle classification method combining air flotation and inclined plates, the method being applied to the micro-particle classification device according to claim 4 or 7, characterized in that the method comprises: Step 1: At the beginning of the experiment, the feed peristaltic pump (102), the blower (307) and the crude product outlet (402) are first turned off, the magnetic stirrer (105) is used to fully stir the material to be classified in the material dispersion tank (101), and the water peristaltic pump (305) is used to inject tap water into the classification device; Step 2: When the classification device is waiting to be filled, the feed peristaltic pump (102) and the blower (307) are turned on, and the material to be classified is driven by the feed peristaltic pump (102) to enter the material distributor (103), and the dispersed material to be classified is preliminarily classified in the barrier column area (2), and is further classified in the air flotation classification system (3) using a large number of fine bubbles for the material in the coarse particle channel; Step 3: Under the action of the first filter membrane (409) and the second filter membrane (410), large particle materials enter the coarse product outlet (402), and small particle materials enter the Y-shaped channel through the aperture of the first filter membrane (409) or the second filter membrane (410), and fine particles are obtained from the fine product outlet (407), finer particles are obtained from the finer product outlet (404), and coarse particles are obtained from the coarse product outlet (402). 9. The micro-particle classification method according to claim 8, characterized in that the material to be classified in the material dispersion tank (101) comprises a dispersant, and the dispersant is one or a combination of hydrophobic nanomaterials, polyethylene glycol and sodium polyacrylate. 10. The micro-particle classification method according to claim 9, characterized in that the solenoid valve (306) corresponding to the blower (307) is used to open or close according to the indication of the pressure gauge (302) in the primary air distributor (303).