Fluidized screening device and method for precise classification of particles

Abstract

The application discloses a fluidized screening device and method for accurate classification of particles. The liquid container is used in cooperation with the drum screen, and suitable hydrodynamic environment is provided for the liquid-phase conductive medium in the liquid container through rotation of the drum screen, so that the agglomerated particles in the slurry to be classified are first fluidized, preliminary dispersion and separation between the particles are realized, and then the accurate interception function of the screen mesh of the drum screen is utilized for particle screening, so that the problems of poor classification accuracy, low precision and low efficiency caused by entrainment or agglomeration existing in the existing particle classification equipment are solved, accurate classification of micron-level particles can be realized, and then the powder with narrow particle size and unimodal distribution is obtained. Since the particles are subjected to pre-dispersion treatment, and the slurry outside and inside the drum screen washes the screen mesh, the accumulation and blockage of the particles on the surface of the screen mesh are effectively avoided, the wear of the screen mesh by the agglomerated large particles is also avoided, and the service life of the drum screen is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of particle grading, in particular to a fluidized screening device and method for precise particle grading. BACKGROUND

[0002] Particle grading technology is widely used in the mineral processing industry and the narrow particle size powder industry such as electrolytic aluminum. The particle size and its distribution of alumina are very important for electrolytic aluminum, and are the primary control index of sand-like alumina. The sand-like alumina has coarse and uniform particle size, good strength, large specific surface area, good dissolution performance and flow performance, and high current efficiency. Therefore, in order to obtain large particle sand-like alumina, the raw material aluminum hydroxide particles need to be precisely graded, and the large particles of aluminum hydroxide after grading are used to produce sand-like alumina, and the small particles can be used as seeds to continue to participate in the reaction crystallization.

[0003] Generally speaking, large particles above the centimeter level can be graded by screening or sedimentation method, but for micron-level particles, on the one hand, due to the mesoscale effect, small particles are inevitably entrained in the flow of large particles during the flow process, resulting in unsatisfactory grading effect. Although the fluid mechanics grading method has high efficiency, it has defects such as poor accuracy and low precision, on the other hand, the intense collision and friction between particles during grading causes static electricity on the surface of fine particles, and in addition to the molecular attraction between small particles, serious agglomeration phenomenon occurs between large and small particles, resulting in that small particles cannot be effectively separated. Although the screening grading method has good accuracy and high separation precision for obtaining target small particles, the grading accuracy and precision are greatly reduced if the target product is a large particle. In addition, due to the common problems such as screen clogging, the grading efficiency is seriously low, which cannot meet the needs of large-scale production. Therefore, the full dispersion of micron-level particles is a prerequisite for precise grading by screening method.

[0004] However, the particle grading equipment commonly used in industry at present, such as hydrocyclone, spiral classifier and vibrating screen, generally lacks the dispersion effect of particles during the grading process, and in addition to the fishhook effect caused by the mesoscale effect of particles, the precision of the fluid mechanics grading method(including hydrocyclone and spiral classifier) is generally less than 70%, and although the screening method(such as vibrating screen) can achieve high grading precision, the small particles are entrained and agglomerated due to friction and electrostatic, which leads to low grading efficiency. In addition, there are problems such as serious wear of screen surface, accumulation of material on screen surface, and easy clogging of screen holes during the grading process using screen, which further reduces the grading efficiency and grading precision, and it is difficult to meet the increasing demand for precise particle grading(grading precision≥90%) and large processing capacity. Therefore, it is necessary to propose a new screening technology for particle grading. SUMMARY

[0005] The present application aims to provide a fluidized screening device and method for accurate classification of particles to solve the problems of poor classification accuracy, low classification precision and low classification efficiency caused by entrainment and tribocharging agglomeration of small particles in the prior art.

[0006] To achieve the above-mentioned purpose, the present application provides the following solutions:

[0007] The present application provides a fluidized screening device for accurate classification of particles, comprising:

[0008] A liquid container is internally used for containing a liquid-phase conductive medium capable of eliminating electrostatic interaction between particles in the slurry to be classified; a fine particle discharge port is further arranged at the bottom of the liquid container;

[0009] A drum screen is rotatably installed above the liquid container through a connecting structure, and the bottom of the drum screen is embedded in the liquid container to be immersed in the liquid-phase conductive medium of the liquid container; the drum screen comprises a drum framework and a screen mesh arranged on the outer periphery of the drum framework, a feed inlet and a residue discharge port are arranged on the drum screen, and the screen mesh allows the liquid phase and fine particles meeting the classification precision in the slurry to be classified to pass through and enter the liquid container;

[0010] A rotary driving mechanism is used to drive the drum screen to rotate, agitate the liquid-phase conductive medium, and disperse the particles that have agglomerated in the slurry to be classified by using the hydrodynamic environment provided by the liquid-phase conductive medium in the drum screen.

[0011] Optionally, the bottom of the liquid container is provided with a conical discharge hopper, and the bottom end of the conical discharge hopper is provided with the fine particle discharge port;

[0012] Alternatively, the bottom of the liquid container is sequentially provided with a plurality of conical discharge hoppers along the flow direction of the material in the drum screen, and the bottom end of any one of the conical discharge hoppers is provided with the fine particle discharge port.

[0013] Optionally, the bottom of the liquid container is sequentially provided with two conical discharge hoppers along the flow direction of the material in the drum screen, and the bottom end of any one of the conical discharge hoppers is provided with the fine particle discharge port.

[0014] Optionally, the drum screen further comprises a cylinder shaft coaxially connected with the drum framework, the connecting structure comprises a bearing seat and a bearing, the bearing seat is arranged on the liquid container, and the cylinder shaft is rotatably connected with the bearing seat through the bearing.

[0015] Optionally, the drum screen further comprises a drum shaft coaxially connected with the drum framework, and the connecting structure comprises a frame, a bearing seat and a bearing, the frame is arranged on both sides of the liquid container, the bearing seat is arranged on the frame, and the drum shaft is rotationally connected with the bearing seat through the bearing.

[0016] Optionally, the feed inlet and the residue discharge outlet are respectively arranged at the axial two ends of the drum screen, and the inner wall of the drum framework is further provided with a spiral vane extending from the feed inlet to the residue discharge outlet, so as to convey the particles intercepted in the screen to the residue discharge outlet.

[0017] Optionally, the drum screen is horizontally or obliquely arranged, and when obliquely arranged, the drum screen is obliquely arranged upward from the feed inlet to the residue discharge outlet, and the inclination angle is not greater than 15°.

[0018] Optionally, the drum screen comprises a first cylindrical segment, a frustoconical segment and a second cylindrical segment arranged in sequence from the feed inlet to the residue discharge outlet, wherein the diameter of the first cylindrical segment is greater than the diameter of the second cylindrical segment, and the large end of the frustoconical segment is connected with the first cylindrical segment, and the small end is connected with the second cylindrical segment.

[0019] Optionally, the spiral vane is provided with intermittent holes, and the pitch of the spiral vane is 1 / 10-1 / 5 of the diameter of the first cylindrical segment.

[0020] Optionally, the top cover is further arranged above the liquid container to encapsulate the drum screen between the liquid container and the top cover.

[0021] The application further provides a fluidized screening method for accurate classification of particles, which is implemented by using the fluidized screening device for accurate classification of particles.

[0022] The liquid-phase conductive medium is injected into the liquid container, and the liquid-phase conductive medium is immersed in the bottom of the drum screen;

[0023] The slurry to be classified is injected into the rotating drum screen, so that the particles in the slurry to be classified are dispersed by the liquid-phase conductive medium and the fluid mechanics generated by the agitation of the liquid-phase conductive medium by the drum screen, and the pre-dispersion treatment of the particles in the slurry to be classified is completed.

[0024] The liquid phase in the slurry to be classified and the fine particles meeting the classification accuracy after the pre-dispersion treatment pass through the screen into the liquid container and are settled in the liquid container, and the coarse particles not meeting the classification accuracy after the pre-dispersion treatment are intercepted in the drum screen by the screen, and the classification of the particles is completed.

[0025] Optionally, the maximum immersion depth of the drum screen in the liquid-phase conductive medium is 1 / 10-2 / 3 of the diameter of the drum screen, and the liquid level in the drum screen is higher than the liquid level of the liquid-phase conductive medium in the liquid container.

[0026] The present application has the following technical effects relative to the prior art:

[0027] The fluidized screening device for precise classification of particles provided by the present application has a novel and reasonable structure, and uses a liquid container in combination with a drum screen. The rotation of the drum screen provides a suitable hydrodynamic environment for the liquid-phase conductive medium in the liquid container, so that the agglomerated particles in the slurry to be classified are first fluidized to achieve preliminary dispersion and separation of the particles, and then the precise screening function of the screen mesh of the drum screen is utilized to screen the particles, thereby solving the problems of poor classification accuracy, low precision and low efficiency caused by entrainment or agglomeration in the existing particle classification equipment, and achieving precise classification of micron-level particles, and further obtaining a powder with narrow particle size and unimodal distribution.

[0028] Meanwhile, since the particles have been pre-dispersed, and the slurry inside and outside the drum screen washes the screen mesh, the particles are effectively prevented from accumulating and clogging on the surface of the screen mesh, and the wear of the screen mesh by large agglomerated particles is also avoided, which is conducive to prolonging the service life of the drum screen.

[0029] The screening method for particle classification provided by the present application is implemented by using the above-mentioned screening device for particle classification, which not only achieves precise classification of solid particles, but also solves the problems of poor classification effect, low classification precision and low classification efficiency caused by entrainment or electrostatic action in the existing particle classification equipment, and can achieve precise classification of micron-level particles. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0031] Figure 1 The structural schematic diagram of the screening device for particle classification disclosed in the embodiments of the present application;

[0032] Figure 2 The structural schematic diagram of the screening device for particle classification disclosed in the embodiments of the present application when equipped with a top cover;

[0033] Figure 3 The overall structure and installation schematic diagram of the drum screen disclosed in the embodiments of the present application;

[0034] Figure 4 Structure diagram of a drum skeleton and a spiral guide vane in a drum screen disclosed in an embodiment of the present application;

[0035] Figure 5 Structure diagram of a liquid container disclosed in an embodiment of the present application;

[0036] Figure 6 Top view of a liquid container disclosed in an embodiment of the present application.

[0037] In the drawings, reference numerals are:

[0038] 100, fluidized screening device for accurate classification of particles;

[0039] 1, liquid container; 11, fine particle discharge port; 12, baffle;

[0040] 2, drum screen; 21, drum skeleton; 211, circular ring frame; 212, long strip frame; 22, screen mesh; 23, feed port; 24, filter residue discharge port; 25, drum shaft; 26, spiral guide vane; 27, first cylindrical section; 28, frustum section; 29, second cylindrical section;

[0041] 3, rotary drive mechanism; 31, motor; 32, transmission wheel; 33, belt;

[0042] 4, connecting structure; 41, frame; 42, bearing seat; 43, bearing;

[0043] 5, top cover. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0045] One of the objectives of the present application is to provide a fluidized screening device for accurate classification of particles to solve the problems of poor classification accuracy, low classification precision and low classification efficiency caused by entrainment and triboelectric agglomeration of small particles in the prior art.

[0046] Another objective of the present application is to provide a fluidized screening method for accurate classification of particles based on the above fluidized screening device for accurate classification of particles to solve the problems of poor classification accuracy, low classification precision and low classification efficiency caused by entrainment and triboelectric agglomeration of small particles in the prior art.

[0047] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] Example 1

[0049] like Figure 1 As shown, this embodiment provides a fluidized bed screening device 100 for precise particle classification, including a liquid container 1, a drum screen 2, and a rotary drive mechanism 3. The liquid container 1 contains a liquid-phase conductive medium that can eliminate electrostatic interactions between particles in the slurry to be classified. A fine particle outlet 11 is also provided at the bottom of the liquid container 1. The drum screen 2 is rotatably mounted above the liquid container 1 via a connecting structure 4, with its bottom embedded within the liquid container 1, so that during actual screening, the particles are separated by the liquid container 1. The liquid conductive medium is immersed in the drum screen 2, which includes a drum frame 21 and a screen 22 set on the outer periphery of the drum frame 21. The drum screen 2 is provided with a feed inlet 23 and a filter residue outlet 24. The screen 22 allows the liquid phase and fine particles that meet the classification accuracy in the slurry to be classified to pass through and enter the liquid container 1. After the fine particles are screened out and enter the liquid container 1, they settle and can be discharged through the fine particle outlet 11 after the screening is completed. Coarse particles that do not meet the classification accuracy are intercepted by the screen 22 in the drum screen 2 and can be discharged through the filter residue outlet 24. The aforementioned rotary drive mechanism 3 is mainly used to drive the drum screen 2 to rotate. Since the bottom of the drum screen 2 is partially immersed in the liquid conductive medium in the liquid container 1, and the slurry to be classified in the drum screen 2 is accumulated at the bottom of the drum screen 2 due to gravity, when the drum screen 2 is driven to rotate, it will agitate the liquid conductive medium in the liquid container 1, causing the liquid conductive medium to turbulently flow, thereby forming a preliminary hydrodynamic classification. At this time, the hydrodynamics (fluidity) of the liquid conductive medium can be used to disperse the agglomerated particles in the slurry to be classified. The agglomerated particles here include agglomerated particles formed by large (coarse) particles carrying small (fine) particles, as well as agglomerated particles formed due to static electricity generated by friction.

[0050] The fluidized screening device 100 for precise classification of particles, by setting the liquid container 1 to cooperate with the drum screen 2, and the bottom of the drum screen 2 is immersed in the liquid phase conducting medium in the liquid container 1 to a certain depth, on the one hand, the liquid phase conducting medium in the drum screen 2 can eliminate the molecular attraction between the particles in the slurry to be classified and the static electricity generated by the mutual friction of small particles during the classification process, avoiding the aggregation of particles caused by static electricity, which is beneficial to promote the effective separation of small particles and large particles; on the other hand, the continuous rotation of the drum screen 2 brings continuous disturbance to the liquid phase conducting medium in the liquid container 1, so that the liquid phase conducting medium in a certain height of the upper part of the liquid container 1 forms and maintains a strong turbulent environment, and the fluid mechanics environment of the liquid phase conducting medium in the screen 22 can realize the full dispersion of fine particles, thereby effectively inhibiting particle inclusion and greatly reducing the concentration of particles that need to be separated on the screen surface, which is beneficial to improve the classification efficiency of particles. In addition, the slurry to be classified in the drum screen 2 is always in the liquid phase conducting medium, which avoids the hardening of the slurry to be classified due to water loss; moreover, the rotation of the drum screen 2 can make the solid particles blocked in the screen hole fall into the slurry to be classified under the action of fluid mechanics and its own gravity, effectively preventing the screen from being blocked; furthermore, the bottom of the drum screen 2 is immersed in the liquid phase conducting medium to a certain depth, and the liquid level of the slurry in the drum screen is higher than that of the liquid phase conducting medium in the liquid container 1, which is beneficial to the entry of the liquid in the slurry into the liquid container 1, and a certain depth of immersion effectively avoids the reduction of classification accuracy caused by the return of the classified particles to the drum screen 2.

[0051] Therefore, the fluidized screening device 100 for precise classification of particles is suitable for micron-level particle classification screening, and the accurate selection of particle size depends on the pore diameter of the selected drum screen 2 screen. By setting the liquid container 1 to cooperate with the drum screen 2, the liquid phase conducting medium in the liquid container 1 can provide a fluid mechanics environment for the pre-dispersion treatment of the agglomerated particles in the slurry to be classified, so that the particles are fully dispersed and fluidized, and then the precise screening function of the drum screen 2 is used for particle screening. By combining the hydraulic classification of fluid mechanics with the accurate screening function of the drum screen, not only the precise classification of solid particles is realized, but also the problem of unsatisfactory classification effect caused by inclusion, static electricity and screen blockage in the existing particle classification equipment is solved.

[0052] In this embodiment, the bottom of the liquid container 1 is provided with a conical discharge hopper, and a fine particle discharge port 11 is formed at the bottom end of the conical discharge hopper. The conical discharge hopper facilitates rapid emptying of the material in the liquid container 1. In addition to this single conical discharge hopper and single fine particle discharge port 11 structure, the embodiment can also use a scheme of providing multiple conical discharge hoppers at the bottom of the liquid container 1, i.e., multiple conical discharge hoppers are provided at the bottom of the liquid container 1 in sequence along the flow direction of the material in the drum screen 2, and each conical discharge hopper has a fine particle discharge port 11 formed at its bottom end. The feed port 23 and the residue discharge port 24 on the drum screen 2 are respectively located at the two axial ends of the drum screen 2. During the flow of the slurry to be classified in the drum screen 2 from the feed port 23 to the residue discharge port 24, the fine particles that meet the classification accuracy in the slurry become less and less, and the closer to the residue discharge port 24, the clearer the liquid filtered by the drum screen 2. Conversely, the closer to the feed port 23, the more fine particles contained in the liquid filtered by the drum screen 2, and the thicker the liquid. The above-mentioned multiple conical discharge hoppers are arranged in sequence from the feed port 23 to the residue discharge port 24, and can collect slurry of different concentrations, which is conducive to the subsequent reclassification and treatment of the slurry.

[0053] As shown in Figure 1 , Figure 2 , Figure 5 and Figure 6 , the bottom of the liquid container 1 is preferably provided with two conical discharge hoppers in sequence along the flow direction of the material in the drum screen. The bottom end of each conical discharge hopper has a fine particle discharge port 11. The two conical discharge hoppers are arranged in close proximity to each other and correspond to the front half (the section close to the feed port 23) and the rear half (the section close to the residue discharge port 24) of the drum screen 2, respectively, and can collect slurry of different concentrations filtered by the drum screen 2.

[0054] Further, in this embodiment, multiple baffles 12 are provided in sequence and spaced apart along the flow direction of the material in the drum screen 2 inside the liquid container 1, as shown in Figure 5 and Figure 6 , three baffles 12 are provided in the liquid container 1. The baffles 12 do not affect the normal rotation and filtering function of the drum screen 2, on the contrary, the slurry filtered by the drum screen 2 will enter the conical discharge hopper under the guidance of the baffles 12. At the same time, the baffles 12 provided in the liquid container 1 can maintain the concentration difference of the fine particles in the liquid container 1, so that the material in the rear half of the drum screen 2 is washed by the relatively clear liquid, and the fine particle entrainment is reduced.

[0055] In the embodiment, the drum screen 2 is preferably in the form of a rotary body, and the drum frame 21 is also in the form of a rotary body. In order to facilitate installation, the drum screen 2 is further provided with a drum shaft 25 coaxially connected with the drum frame 21. The drum shaft 25 can be connected at the axial ends of the drum frame 21 or can penetrate the axial direction of the drum frame 21 and extend out of the axial ends of the drum frame 21 to form connecting portions. In order to ensure the structural strength of the entire drum screen 2, the drum shaft 25 is preferably in the form of a whole shaft, which penetrates the axial direction of the drum frame 21 and is connected with the drum frame 21. The two ends of the drum shaft 25 extend out of the axial ends of the drum frame 21 to form connecting portions.

[0056] Further, the drum screen 2 can be directly installed on the liquid container 1 through the drum shaft 25 and the connecting structure 4. Here, the connecting structure 4 only includes a bearing seat 42 and a bearing 43. The bearing seat 42 is arranged on the liquid container 1, and the drum shaft 25 is rotatably connected with the bearing seat 42 through the bearing 43. In addition to the above installation form, the drum screen 2 can also be installed on other auxiliary structures other than the liquid container 1 through the drum shaft 25. At this time, in addition to the bearing seat 42 and the bearing 43, the connecting structure 4 further includes two groups of racks 41. As shown in Figure 1 The two groups of racks 41 are respectively located on the two sides of the liquid container 1. The bearing seat 42 is arranged on the rack 41, and the two ends of the drum shaft 25 are respectively rotatably connected with the bearing seats 42 on the two racks 41 through the bearings 43. The above two installation forms of the drum screen 2 can suspend the drum screen 2 above the liquid container 1 to meet the relative positional relationship between the drum screen 2 and the liquid container 1. However, compared with the former, the latter can easily move the drum screen 2 according to the needs, is more portable after disassembly and assembly, is more conducive to the independent maintenance of the drum screen 2 and the liquid container 1, and is more convenient and flexible to use. Therefore, the connecting structure 4 including the rack 41 is preferably used to install the drum screen 2.

[0057] In the embodiment, the rotating drive mechanism 3 can adopt a transmission belt type drive mechanism, a transmission chain type drive mechanism, or a gear drive mechanism. The gear drive mechanism includes a motor, a driving gear, and a driven gear. The driving gear is sleeved on the output end of the motor, and the driven gear is sleeved on the drum shaft 25. The driving gear and the driven gear are engaged with each other. By driving the motor, the driven gear and the drum shaft 25 can be driven to rotate by the driving gear. The transmission belt type drive mechanism specifically includes a motor 31, a transmission wheel 32, and a belt 33, as shown in Figure 1As shown, the transmission wheel 32 is arranged on the cylinder shaft 25, the output shaft of the motor 31 is connected with the transmission wheel 32 through the closed loop belt 33, and the motor 31 is started to drive the output shaft to drive the transmission wheel 32 and the cylinder shaft 25 to rotate through the belt 33. The transmission chain drive mechanism is only different from the transmission belt drive mechanism in that the belt 33 is replaced by a chain. As a preferred solution, the above-mentioned transmission belt drive mechanism is adopted. The rotation speed of the above-mentioned transmission belt drive mechanism for driving the drum screen 2 to rotate is not more than 200 r / min.

[0058] In the embodiment, in order to prolong the particle screening path and improve the particle screening accuracy, the feed inlet 23 and the residue discharge outlet 24 are preferably arranged at the axial ends of the drum screen 2. As a further preferred solution, the feed inlet 23 and the residue discharge outlet 24 are both circular inlets coaxial with the drum screen 2, and annular gaps are formed between the feed inlet 23 and the residue discharge outlet 24 and the cylinder shaft 25, which can allow the to-be-classified slurry to enter the drum screen 2 or allow the coarse particle residue intercepted by the screen mesh 22 to be discharged from the drum screen 2. Meanwhile, the inner wall of the drum framework 21 is also provided with a spiral guide vane 26 extending from the feed inlet 23 to the residue discharge outlet 24, which can push the to-be-classified slurry from the feed inlet 23 to the residue discharge outlet 24, so that the to-be-classified slurry is conveyed and filtered at the same time. In the process of pushing the to-be-classified slurry to the residue discharge outlet 24, the pre-dispersion of particles and the filtration of fine particles are completed, and finally the coarse particle residue in the to-be-classified slurry basically reaches the residue discharge outlet 24. It should be noted that the coarse particle residue intercepted by the screen mesh 22 is relative to the size of the particles passing through the screen mesh 22, which is only the particles screened out by the drum screen 2, and is not the final waste in the particle classification work. The coarse particle residue discharged from the drum screen 2 can also be used as raw material for another related process.

[0059] In the embodiment, the drum screen 2 is arranged horizontally or obliquely, and when arranged obliquely, the drum screen 2 is inclined upward from the feed inlet 23 to the residue discharge outlet 24, and the inclination angle a is not greater than 15°, i.e. 0° < a ≤ 15°. The inclination angle of the drum screen 2 can be realized by replacing the racks 41 with different heights, or by setting the racks 41 as height-adjustable structures, such as electric telescopic rods, hydraulic telescopic rods, electric sliding tables, etc., by adjusting the heights of the racks 41 on both sides to different heights and adjusting the corresponding angles of the bearing seats, to realize the adjustment of the inclination angle of the drum screen 2.

[0060] In the embodiment, in order to facilitate the collection and discharge of the coarse particle residue at the residue discharge outlet 24, the drum screen 2 is preferably arranged in a tapered manner as a whole, i.e. the diameter of the drum screen 2 gradually decreases from the feed inlet 23 to the residue discharge outlet 24, such as being arranged in a frustum shape as a whole or in a segmented manner. When arranged in a segmented manner, as shown in FIG. 4, the drum screen 2 is divided into a plurality of segments, and the diameters of the segments gradually decrease from the feed inlet 23 to the residue discharge outlet 24. Figures 3-4As shown, the drum screen 2 comprises a first cylindrical section 27, a frustum section 28 and a second cylindrical section 29 arranged in sequence from the feed inlet 23 to the residue outlet 24. The diameter of the first cylindrical section 27 is greater than that of the second cylindrical section 29. The large end of the frustum section 28 is connected with the first cylindrical section 27, and the small end is connected with the second cylindrical section 29. The frustum section 28 is arranged to realize the diameter reduction of the drum screen 2 in the axial direction. As a preferred solution, the axial length of the first cylindrical section 27 can be 1 m, and the diameter can be 0.5 m. The axial length of the frustum section 28 can be 0.5 m, and the diameter of the second cylindrical section 29 can be 0.2 m, and the axial length can be 0.2 m. In the drum screen 2, the first cylindrical section 27 of the drum screen 2 is mainly immersed in the liquid-phase conductive medium in the liquid container 1. Generally, the maximum depth of the first cylindrical section 27 immersed in the liquid-phase conductive medium is preferably 1 / 10-2 / 3 of the diameter of the first cylindrical section 27. Taking the diameter of the first cylindrical section 27 as 0.5 m as an example, the depth of the first cylindrical section 27 immersed in the liquid-phase conductive medium can be 1 / 10 of the diameter, i.e. 5 cm.

[0061] In this embodiment, the spiral guide vane 26 is attached to the inner wall of the drum skeleton of the drum screen 2. Under the condition that the spiral pitch is unchanged, the spiral guide vane 26 is arranged according to the trend of the large-diameter cylindrical section, the frustum section and the small-diameter cylindrical section to realize the diameter reduction.

[0062] In this embodiment, the overall profile of the drum skeleton 21 is consistent with the profile of the drum screen 2. As shown in Figure 3 and Figure 4 As shown, the drum skeleton 21 is composed of a plurality of circular ring frames 211 arranged in the axial direction. The diameter of the circular ring frame 211 located in the first cylindrical section 27 is greater than that of the circular ring frame 211 located in the second cylindrical section 29, and no circular ring frame 211 is arranged at the position corresponding to the frustum section 28. The circular ring frames 211 located in the first cylindrical section 27 are connected and fixed by the long strip frame 212 corresponding to the axial length of the first cylindrical section 27. The circular ring frames 211 located in the second cylindrical section 29 are connected and fixed by the long strip frame 212 corresponding to the axial length of the second cylindrical section 29. The two parts of the skeleton are directly connected by the screen mesh 22 to form the frustum section 28. The screen mesh 22 of the frustum section 28 is mainly supported and shaped by the spiral guide vane 26. The long strip frame 212 is preferably an oblong plate, such as an oblong steel strip. Each circular ring frame 211 is also enclosed by an oblong plate, such as a steel strip. The drum skeleton 21 and the drum shaft 25 can be connected to form an integral whole by the ribs arranged in the radial direction of the drum skeleton 21.

[0063] In the embodiment, the first cylindrical section 27 is the main section of the drum screen 2, and the pitch of the spiral vanes 26 is preferably 1 / 10-1 / 5 of the diameter of the first cylindrical section 27. Taking the diameter of the first cylindrical section 27 as 0.5 m as an example, the pitch of the spiral vanes 26 can be 1 / 10 of the diameter, i.e. 5 cm. In the actual test process, the slurry height in the drum screen 2 must be lower than the height of the spiral vanes 26, i.e. the slurry does not fill the drum screen 2, and the spiral vanes 26 need to be exposed above the slurry level (i.e. the liquid level cannot submerge the spiral vanes), which can improve the separation precision, and the height of the spiral vanes 26 is preferably higher than the maximum immersion depth 4 cm of the drum screen 2 in the liquid container 1, i.e. the height of the spiral vanes 26 is 9 cm.

[0064] In the embodiment, the spiral vanes 26 are intermittently perforated, and the perforations on the frustoconical section spiral vanes prolong the residence time of the mother liquor (slurry in the drum screen 2), which can effectively prevent the entrainment of small particles in the mother liquor and obtain dry solid large particles. As a preferred solution, the spiral vanes 26 are perforated at intervals of 0.2 m, and the perforations can be square or circular, etc., and the perforations are intermittently perforated along the spiral direction of the spiral vanes 26. Taking the square perforations as an example, the size of the square perforations can be 2 cm x 3 cm.

[0065] In the embodiment, the screen 22 is preferably a 180-mesh stainless steel screen.

[0066] In the embodiment, in order to avoid the to-be-classified slurry splashing everywhere during the screening process, a top cover 5 is further arranged above the liquid container 1 to package the drum screen 2 between the liquid container 1 and the top cover 5, and the top cover 5 also protects the drum screen 2. The top cover 5 and the liquid container 1 are preferably detachably connected, the liquid container 1 can be a cuboid container, and the fine particle discharge port 11 thereof is arranged close to the bottom of the cuboid container; the top cover 5 is preferably a semi-cylindrical shape that matches the outer contour of the first cylindrical section 27 of the drum screen 2. The top cover 5 is provided with a feed inlet avoiding hole and a filter residue discharge port avoiding hole at two ends thereof, so as to ensure that when the top cover 5 covers the drum screen 2, the drum screen 2 can normally feed and discharge.

[0067] The fluidized screening device 100 for precise classification of particles in use first injects the liquid-phase conductive medium into the liquid container 1 and makes it submerge the bottom of the drum screen 2 by a certain height; then the slurry to be classified is fed into the drum screen 2 rotating at a certain speed, the conductivity of the liquid-phase conductive medium in the drum screen 2 is used to eliminate the electrostatic effect between the particles in the slurry to be classified, at the same time, the continuous rotation of the drum screen 2 is used to stir the liquid-phase conductive medium, so that the liquid-phase conductive medium generates strong turbulent flow state, the liquid-phase conductive medium is used to fully disperse and fluidize the slurry to be classified by fluid mechanics, so as to avoid the agglomeration of particles due to entrainment or electrostatic friction, and complete the pre-dispersion treatment of the particles in the slurry to be classified; then, the liquid phase in the slurry to be classified and the fine particles meeting the classification accuracy after the pre-dispersion treatment pass through the screen mesh 22 into the liquid container 1 and settle in the liquid container 1; the coarse particles not meeting the classification accuracy after the pre-dispersion treatment are intercepted by the screen mesh 22 in the drum screen 2 and are sent to the filter residue discharge port 24 under the propulsion of the spiral guide vane 26, so as to complete the classification of particles. For the sedimentation classification of micron-level particles, two requirements must be met: one is to make the particles fully dispersed, and the other is to have a strong enough supergravity field to accelerate the sedimentation of particles and increase the sedimentation speed difference between particles, and the present scheme meets the above two requirements by arranging the drum screen 2 and the liquid container 1 upside down and cooperating with each other, which is suitable for the sedimentation classification of micron-level particles.

[0068] The working process, working principle and working effect of the fluidized screening device 100 for precise classification of particles in the present embodiment will be described in detail below with specific examples.

[0069] Example 1

[0070] The liquid-phase conductive medium is sodium hydroxide lye, and the slurry to be classified is aluminum hydroxide slurry; the drum screen 2 is horizontally arranged; the screen mesh 22 is a 180-mesh stainless steel screen mesh; the first cylindrical section 27 has a diameter of 0.5 m and an axial length of 1 m, the frustum section 28 has an axial length of 0.5 m, and the second cylindrical section 29 has a diameter of 0.2 m; the maximum immersion depth of the bottom of the drum screen 2 in the liquid container 1 is 1 / 10 of the diameter of the first cylindrical section 27, i.e. 5 cm; the pitch of the spiral guide vane 26 is 1 / 10 of the diameter of the first cylindrical section 27, i.e. 5 cm; the height of the spiral guide vane 26 is 4 cm higher than the maximum immersion depth of the drum screen 2 in the liquid container 1, i.e. the height of the spiral guide vane 26 is 9 cm, which can ensure that the liquid surface does not submerge the spiral guide vane 26, so as to improve the separation accuracy.

[0071] The feed concentration of the aluminum hydroxide slurry shown in Table 1 is injected from the feed port 23 into the drum screen 2 at a feed rate of 180 L / h, and the drum screen 2 rotates at a uniform speed of 6 r / min. Since the drum screen 2 is immersed in the sodium hydroxide lye in the liquid container 1, it can bring continuous disturbance to the sodium hydroxide lye in the upper part of the liquid container 1, making it a turbulent environment. The aluminum hydroxide slurry is first fully fluidized in the lye at the bottom of the drum screen 2, allowing the particles to be preliminarily separated, and at the same time eliminating the electrostatic effect between the particles and avoiding the phenomenon of particle agglomeration, hardening and clogging. The fine particles passing through the screen 22 of the drum screen 2 can gradually settle and collect at the bottom of the liquid container 1 due to less disturbance in the lower part of the liquid container 1, and finally be discharged through the fine particle discharge port 11. The fluidized screening device 100 for precise classification of particles is continuously operated for 20 min, and the classification effect is shown in Table 1.

[0072] Example 2

[0073] The structure of the fluidized screening device 100 for precise classification of particles used in this example is the same as that of Example 1, and the experimental conditions and methods are also the same. The difference is that the drum screen 2 is inclined, and the inclination angle is 10°; the maximum immersion depth of the bottom of the drum screen 2 in the liquid container 1 is 1 / 5 of the diameter of the first cylindrical section 27, i.e. 10 cm; the pitch of the spiral guide vane 26 is 3 / 20 of the diameter of the first cylindrical section 27, i.e. 7.5 cm; the height of the spiral guide vane 26 is 3 cm higher than the maximum immersion depth of the drum screen 2 in the liquid container 1, i.e. the height of the spiral guide vane 26 is 13 cm.

[0074] The classification effect of this example is shown in Table 1.

[0075] Example 3

[0076] The structure of the fluidized screening device 100 for precise classification of particles used in this example is the same as that of Example 1, and the experimental conditions and methods are also the same. The difference is that the drum screen 2 is inclined, and the inclination angle is 15°; the maximum immersion depth of the bottom of the drum screen 2 in the liquid container 1 is 2 / 3 of the diameter of the first cylindrical section 27, i.e. 33.3 cm; the pitch of the spiral guide vane 26 is 1 / 5 of the diameter of the first cylindrical section 27, i.e. 10 cm; the height of the spiral guide vane 26 is 3 cm higher than the maximum immersion depth of the drum screen 2 in the liquid container 1, i.e. the height of the spiral guide vane 26 is 36.3 cm. This structure can ensure that the liquid surface does not submerge the spiral guide vane 26, thereby improving the separation precision.

[0077] The classification effect of this example is shown in Table 1.

[0078] Table 1 - Comparison of particle classification effects of Examples 1-3.

[0079]

[0080] From the above Table 1, in Examples 1-3, the target coarse particle content of +75 μm in the sample of the filter residue discharge port 24 is all above 93%, which is greatly improved compared with the sample of the feed slurry, and after classification by the equipment proposed in the present scheme, no small particles of -45 μm are detected in the filter residue discharge port 24, indicating that the fluidized screening device 100 for precise classification of particles proposed in the present scheme has excellent classification effect on aluminum hydroxide slurry. The classification effect of Example 2 is the best, which is due to the fact that the inclination, immersion depth, pitch and spiral height of Example 2 are all relatively appropriate, so that the whole device is in a relatively good operating condition.

[0081] Example 4

[0082] This example has the same structure of the fluidized screening device 100 for precise classification of particles as that used in Example 2, except that the screen 22 is a 150-mesh stainless steel screen, and the slurry treated is phosphate ore slurry, and the liquid-phase conductive medium is tap water.

[0083] The phosphate ore slurry with the feed concentration shown in Table 2 is injected from the feed port 23 into the drum screen 2 at a feed rate of 1200 L / h, and the drum screen 2 rotates at a uniform speed of 150 r / min. Since the drum screen 2 is immersed in the tap water in the liquid container 1, it can bring continuous disturbance to the tap water in the upper part of the liquid container 1, so that it is in a turbulent environment. The phosphate ore slurry is first fully fluidized in the alkali solution at the bottom of the drum screen 2, so that the particles are preliminarily separated, and at the same time, the electrostatic effect between the particles is eliminated, avoiding the phenomena of particle agglomeration, hardening and clogging. The fine particles passing through the screen 22 of the drum screen 2 gradually settle and collect at the bottom of the liquid container 1 due to less disturbance in the lower part of the liquid container 1, and are finally discharged through the fine particle discharge port 11. After the fluidized screening device 100 for precise classification of particles is continuously operated for 120 min, a sample is taken at the filter residue discharge port 24, and the classification effect is shown in Table 2.

[0084] Table 2 - Classification effect of particles in Example 4.

[0085]

[0086] It can be known from the above that the liquid container 1 is used in cooperation with the drum screen 2, the fluid mechanics environment provided by the liquid-phase conductive medium in the liquid container 1 can make the agglomerated particles in the slurry to be classified be pre-dispersed, the preliminary dispersion and separation between the particles are realized, then the precise interception function of the drum screen 2 is used for particle classification, the precise classification of the solid particles is realized, the problems of poor classification effect, low classification precision and low classification efficiency caused by entrainment or electrostatic effect existing in the existing particle classification equipment are solved, and the precise classification of the micron-level particles is suitable. Meanwhile, since the particles are pre-dispersed, and the fluid impact of the liquid-phase conductive medium on the screen is combined, the accumulation and clogging of the particles on the screen surface are effectively avoided, the wear of the agglomerated large particles on the screen surface is also avoided, and the service life of the drum screen 2 is prolonged.

[0087] Example two

[0088] The present embodiment provides a screening method for particle classification, which is implemented by using the fluidized screening device 100 for particle precise classification disclosed in the example one, and mainly includes the following steps.

[0089] The liquid-phase conductive medium is injected into the liquid container 1, and the liquid-phase conductive medium is immersed in the drum screen 2 to a certain height;

[0090] The slurry to be classified is injected into the drum screen 2 rotating at a certain speed, and the liquid level of the slurry to be classified is generally higher than the liquid level of the liquid-phase conductive medium immersed in the drum screen 2 (that is, the liquid level of the slurry to be classified injected into the drum screen 2 is higher than the liquid level of the liquid-phase conductive medium in the liquid container 1). The drum screen 2 is rotated to stir the liquid-phase conductive medium, so as to disperse the agglomerated particles in the slurry to be classified by using the liquid-phase conductive medium and the fluid mechanics generated by the stirring of the liquid-phase conductive medium by the drum screen 2, and complete the pre-dispersion treatment of the particles in the slurry to be classified;

[0091] The liquid phase in the slurry to be classified and the fine particles meeting the classification precision after the pre-dispersion treatment pass through the screen 22 into the liquid container 1 and are settled in the liquid container 1. The coarse particles not meeting the classification precision after the pre-dispersion treatment are intercepted by the screen 22 in the drum screen 2, and the particle classification is completed. Since the spiral guide vane 26 is further arranged, the coarse particle residues intercepted by the screen 22 in the drum screen 2 are pushed by the spiral guide vane 26, are sent to the filter residue discharge port 24 and are discharged.

[0092] The screening method for particle classification of the present scheme uses the liquid container 1 in cooperation with the drum screen 2, and submerges the bottom of the drum screen 2 in the liquid phase conductive medium in the liquid container 1 to a certain depth. On the one hand, the liquid phase conductive medium in the drum screen 2 can eliminate the molecular attraction between particles in the slurry to be classified and the electrostatic effect generated by the mutual friction of small particles during the classification process, thereby avoiding the agglomeration of particles caused by electrostatic effect and facilitating the effective separation of small particles and large particles. On the other hand, the continuous rotation of the drum screen 2 brings continuous disturbance to the liquid phase conductive medium in the liquid container 1, so that the liquid phase conductive medium in a certain height of the upper part of the liquid container 1 forms and maintains a strong turbulent environment. By using the fluid mechanics environment of the liquid phase conductive medium in the screen 22, the fine particles can be fully dispersed and fluidized, thereby effectively inhibiting particle inclusion and greatly reducing the concentration of particles to be separated on the screen surface, which is conducive to improving the classification efficiency of particles. In addition, the slurry to be classified in the drum screen 2 is always in the liquid phase conductive medium, which avoids the hardening of the slurry to be classified due to water loss. Furthermore, the rotation of the drum screen 2 can make the solid particles blocked in the screen mesh fall back into the slurry to be classified under the action of fluid mechanics and its own gravity, effectively preventing the screen from being blocked. Moreover, the submersion of the bottom of the drum screen 2 in the liquid phase conductive medium to a certain depth and the high liquid level of the slurry in the drum screen 2 relative to the liquid level of the liquid phase conductive medium in the liquid container 1 are conducive to the entry of the liquid in the slurry into the liquid container 1, effectively avoiding the reduction of classification accuracy caused by entrainment of mother liquor (i.e. slurry).

[0093] Therefore, the screening method for particle classification described above is suitable for micron-level particle classification and screening. By using the liquid container 1 in cooperation with the drum screen 2, the agglomerated particles in the slurry to be classified are first pre-dispersed by the fluid mechanics environment provided by the liquid phase conductive medium in the liquid container 1, so that the particles are fully dispersed and fluidized, and then the particles are screened by the precise interception function of the drum screen 2. By combining the hydraulic classification of fluid mechanics with the accurate interception function of the screen mesh of the drum screen, not only the precise classification of solid particles is realized, but also the problem of poor classification effect caused by particle agglomeration and lack of dispersion in the existing particle classification equipment is solved, and the screen mesh is effectively prevented from being blocked.

[0094] It should be noted that for those skilled in the art, it is obvious that the present application is not limited to the details of the above exemplary embodiments, and the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application, and any reference signs in the claims should not be considered as limiting the claims involved.

[0095] The principles and implementation manners of the present application are described by using specific examples in the present application, and the above examples are only used for helping to understand the method of the present application and its core idea; meanwhile, for the general technical personnel in the art, according to the idea of the present application, the specific implementation manners and application ranges will be changed. In conclusion, the content of the present specification should not be understood as the limitation of the present application.

Claims

1. A fluidized screening device for precise classification of particles, characterized in that, The application relates to a liquid container, a drum screen and a method for pre-dispersing particles in slurry. The liquid container is internally used for containing liquid-phase conductive medium capable of eliminating electrostatic interaction between particles in slurry to be classified; a fine-particle discharge port is arranged at the bottom of the liquid container; The drum screen is rotatably arranged above the liquid container through a connecting structure, and the bottom of the drum screen is embedded in the liquid container to be immersed in the liquid-phase conductive medium in the liquid container; the drum screen comprises a drum framework and a screen mesh arranged at the outer periphery of the drum framework; a feeding port and a residue discharge port are arranged on the drum screen; the screen mesh allows liquid phase in the slurry to be classified and fine particles meeting classification precision to pass through and enter the liquid container; A rotary driving mechanism is used for driving the drum screen to rotate, agitating the liquid-phase conductive medium, and dispersing particles in the slurry to be classified in a fluid mechanics environment provided by the liquid-phase conductive medium in the drum screen.

2. Fluidized screening device for precise classification of particles according to claim 1, characterized in that The bottom of the liquid container is provided with a conical discharge hopper, and the bottom end of the conical discharge hopper is provided with the fine-particle discharge port; Alternatively, the bottom of the liquid container is sequentially provided with a plurality of conical discharge hoppers along the flow direction of materials in the drum screen, and the bottom end of any one of the conical discharge hoppers is provided with the fine-particle discharge port.

3. Fluidized screening device for precise classification of particles according to claim 1, characterized in that The drum screen further comprises a drum shaft coaxially connected with the drum framework; the connecting structure comprises a rack, a bearing seat and a bearing; the rack is arranged on both sides of the liquid container; the bearing seat is arranged on the rack; and the drum shaft is rotatably connected with the bearing seat through the bearing.

4. Fluidized screening device for precise classification of particles according to any one of claims 1 to 3, characterized in that The feeding port and the residue discharge port are respectively arranged at the axial two ends of the drum screen; and the inner wall of the drum framework is further provided with a spiral guide vane extending from the feeding port to the residue discharge port, so as to convey particles intercepted in the screen mesh to the residue discharge port.

5. Fluidized screening device for precise classification of particles according to claim 4, characterized in that The drum screen is horizontally or obliquely arranged, and when the drum screen is obliquely arranged, the drum screen is upwardly inclined from the feeding port to the residue discharge port, and the inclination angle is not greater than 15 degrees.

6. Fluidized screening device for precise classification of particles according to claim 4, characterized in that The drum screen comprises a first cylindrical segment, a frustum segment and a second cylindrical segment arranged in sequence from the feeding port to the residue discharge port; the diameter of the first cylindrical segment is greater than that of the second cylindrical segment; and the large end of the frustum segment is connected with the first cylindrical segment, and the small end is connected with the second cylindrical segment.

7. Fluidized screening device for precise classification of particles according to claim 6, characterized in that The spiral guide vane is provided with intermittent holes, and the pitch of the spiral guide vane is 1 / 10-1 / 5 of the diameter of the first cylindrical segment.

8. Fluidized screening device for precise classification of particles according to claim 4, characterized in that A top cover is further arranged above the liquid container to encapsulate the drum screen between the liquid container and the top cover.

9. A fluidized screening method for precise classification of particles, which is implemented using the fluidized screening device for precise classification of particles according to any one of claims 1 to 8, characterized in that, The method comprises the following steps: injecting liquid-phase conductive medium into the liquid container, so that the liquid-phase conductive medium immerses the bottom of the drum screen; injecting slurry to be classified into the rotating drum screen, so as to disperse particles in the slurry to be classified by using the liquid-phase conductive medium and fluid mechanics generated by agitating the liquid-phase conductive medium by the drum screen, and complete pre-dispersing treatment of particles in the slurry to be classified; The liquid phase in the slurry to be classified and the fine particles meeting the classification accuracy after the pre-dispersion treatment pass through the screen into the liquid container and settle in the liquid container; the coarse particles not meeting the classification accuracy after the pre-dispersion treatment are intercepted by the screen in the drum screen, thereby completing the classification of the particles.

10. Fluidized screening method for precise classification of particles according to claim 9, characterized in that: The maximum immersion depth of the drum screen in the liquid phase conductive medium is 1 / 10-2 / 3 of the diameter of the drum screen, and the liquid level in the drum screen is higher than the liquid level of the liquid phase conductive medium in the liquid container.

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