Fluidized grinding ball device

Abstract

The invention discloses a fluidized grinding ball device, and belongs to the technical field of ceramsite preparation. The fluidized ball grinding device is used for molding to-be-treated particles into balls and / or grinding the to-be-treated particles into spherical particles in a fluidized manner; the fluidization ball grinding device comprises a first screen, a second screen and a third screen, wherein the first screen is arranged at the lower part of the fluidization ball grinding device; the cover barrel comprises a circular-truncated-cone-shaped barrel and a cylindrical barrel which are spliced together, and the periphery of the end, with the smaller radius, of the circular-truncated-cone-shaped barrel is connected with the periphery of the first screen; the grinding rod assembly comprises a plurality of grinding rods with rough surfaces, and the multiple grinding rods are vertically and fixedly arranged on the first screen and located in the cover barrel; and the fluidizing device is used for introducing fluidizing air which enables the to-be-treated particles to continuously collide with the plurality of polishing rods. According to the fluidized ball grinding device, particles in different shapes can be ground into spherical particles according to different particle size requirements, and the particle size uniformity of the spherical particles obtained through grinding is high.

Description

[0001] This application is a divisional application based on a patent application with an application date of September 6, 2024, an application number of 202411245058.2, and an invention name of "Fluidized ball grinding device and ball grinding method using the same". Technical Field

[0002] The invention belongs to the technical field of ceramsite preparation, and in particular relates to a fluidized ball grinding device. Background Art

[0003] Spherical ceramsite is used in many industrial processes, such as zirconium oxide and silicon carbide balls as grinding media for ball milling, aluminum oxide, silicon oxide, titanium oxide, and zirconium oxide balls as catalyst carriers for industrial catalysis, etc. Many applications require spherical ceramsite to have high particle size uniformity: for example, the ball milling process requires the grinding medium to have uniform particle size, otherwise it is easy to cause the grinding product to have poor particle size uniformity; catalyst carriers with poor particle size uniformity affect the uniformity of catalyst loading and the uniformity of catalytic reactions, especially for the uniformity of catalytic reactions in moving beds and fluidized beds, which ultimately reduces the yield or selectivity of catalytic reactions.

[0004] The main method for preparing spherical ceramsite in industry is rolling molding, that is, first obtaining strip-shaped plastic particles by extrusion, and then rolling the plastic in a particle spheronizer to reshape the strip-shaped particles into spheres. This method has a large output, a simple method, and a wide range of applications. However, the rolling time of the particle spheronization method is short (usually no more than 5 minutes, rarely more than 10 minutes), and the single plastic particle has high humidity and good internal adhesion. It is not easy to drop powder due to grinding during the rolling process. Its quality remains basically unchanged during the rolling process, and multiple particles are easy to aggregate and bond.

[0005] Therefore, the length of the extruded plastic determines the particle size of the product pellets, and the uneven extrusion length will directly lead to the uneven particle size of the product. The relative deviation of the length distribution of the strip extrudate increases as the target particle size decreases, so this method is more suitable for producing particles larger than 5 mm, while the particle size uniformity is poor when the target particle size is smaller (such as less than 5 mm). Summary of the invention

[0006] In view of this, the object of the present invention is to provide a fluidized ball grinding device and a ball grinding method using the fluidized ball grinding device, wherein the fluidized ball grinding device and the ball grinding method using the fluidized ball grinding device can grind particles of different shapes into spherical particles according to different particle size requirements, and the particle size uniformity of the spherical particles obtained by grinding is high. The technical solution is as follows:

[0007] According to one aspect of the present invention, a fluidized ball grinding device is provided.

[0008] The fluidized ball grinding device is used to shape the particles to be processed into spheres and / or grind them into spherical particles in a fluidized manner; the fluidized ball grinding device comprises:

[0009] a first screen, the first screen being arranged to be located at a lower part of the fluidized ball grinding device;

[0010] A cover barrel, the cover barrel comprises a truncated cone barrel and a cylindrical barrel spliced ​​together, and the outer periphery of one end of the truncated cone barrel with a smaller radius is connected to the outer periphery of the first screen;

[0011] A grinding rod assembly, the grinding rod assembly comprising a plurality of grinding rods with rough surfaces, the plurality of grinding rods being vertically fixedly disposed on the first screen and located in the cover barrel; and,

[0012] The fluidizing device is used to introduce fluidizing air to make the particles to be processed collide with a plurality of grinding rods continuously.

[0013] In some embodiments, the combination of a fluidizing device and a grinding rod assembly is used to achieve shaping and grinding of the particles to be processed; the number of the multiple grinding rods is not less than 10, the multiple grinding rods are arranged in a hexagonal shape, the distance between the multiple grinding rods is 0.2 to 3 cm, and the multiple grinding rods are higher than the upper end plane of the truncated cone barrel, but do not exceed the upper end plane of the cylindrical barrel.

[0014] In some embodiments, the plurality of grinding rods are higher than the height of the truncated cone barrel but not more than 3 / 4 of the height of the cylindrical barrel; the fluidized ball grinding device also includes a second screen, which is arranged directly below the first screen, and the periphery of the second screen is movably connected to the periphery of the first screen; the second screen is used to prevent the particles to be processed from falling into the fluidized device.

[0015] According to another aspect of the present invention, a ball grinding method using the fluidized ball grinding device is provided. The ball grinding method comprises the following steps:

[0016] Pour the particles to be processed into the cover barrel of the fluidized ball grinding device;

[0017] Fluidized air of a first air volume is introduced until the sphericity of the particles reaches a preset target, and the fluidized air of the first air volume is used to make the particles to be processed continuously collide with the rough outer walls of multiple grinding rods, and the highest height of the particles to be processed blown up does not exceed the height of the multiple grinding rods.

[0018] In some embodiments, in the first stage, the particles to be processed are wet non-spherical plastic particles, and the fluidizing device causes the non-spherical plastic particles to gradually be shaped into a spherical shape during continuous collision with multiple grinding rods and the wall of the barrel under turbulent fluidization; in the second stage, as the particles to be processed dry from the surface to the inside, the surface of the particles to be processed gradually wears away, the mass of a single particle to be processed becomes smaller, and the height of the particle blown up in the fluidizing device gradually increases until ground particles are produced, wherein the water content of the particles to be processed is 25% to 70%.

[0019] In some embodiments, when the sphericity of the ground particles does not reach the expected target, water is sprayed into the cover barrel from the top of the fluidized ball grinding device to slow down the drying speed of the particles to be processed and extend the shaping time; by controlling a predetermined proportion of the particles to be processed to be blown up to a higher height, the rate of wear on the larger particles to be processed is faster, so that the larger particles to be processed are ground faster and the smaller particles to be processed are ground slower, and the size of the particles to be processed gradually converges with the fluidization process; during the grinding process, samples are taken at any time to detect the particle size, particle size distribution span and aspect ratio of the particles to be processed; during the fluidization process, the fluidization device dries the particles to be processed from the outside to the inside, so that the particles to be processed with dry surface will not stick together.

[0020] In some embodiments, the first air volume is calculated according to the following formula:

[0021] A 1 =5.29-a+8.73×D 50 +20.0×ρ;

[0022] Among them, A 1 is the first air volume, D 50 is the average particle size of the particles to be treated, ρ is the average bulk density of the particles to be treated, and a is a constant greater than 2;

[0023] The larger the aspect ratio of the particles to be processed is, the smaller the first air volume is set to; the larger the bed thickness of the particles to be processed is, the larger the first air volume is set to.

[0024] In some embodiments, the proportion of particles to be processed whose height exceeds the top of multiple grinding rods = sampling weight of bottom barrel sampler / (sampling weight of bottom barrel sampler + sampling weight of middle barrel sampler in the same time interval) × 100%, wherein the bottom barrel sampler takes samples from the bottom of the cover barrel, and the middle barrel sampler takes samples at a height higher than multiple grinding rods in the cover barrel.

[0025] In some embodiments, the ball grinding method further comprises the following steps:

[0026] The air volume of the fluidizing air is continuously adjusted to keep a preset percentage of the particles to be processed being blown up to a maximum height exceeding the height of a plurality of grinding rods;

[0027] When the particles to be processed meet the preset particle size target, stop the fluidizing air.

[0028] The preset percentage is 20% to 30%.

[0029] In some embodiments, the air volume of the fluidizing air is continuously adjusted by first increasing the air volume to the second air volume and then gradually decreasing the air volume to the third air volume.

[0030] The fluidized ball grinding device and the ball grinding method using the fluidized ball grinding device provided by the embodiments of the present invention have at least one or part of the following advantages:

[0031] (1) The fluidized ball grinding device provided in the embodiment of the present invention adopts a method combining a fluidization process and a grinding rod to achieve shaping (first stage) and grinding (second stage) of the particles to be processed. In the first stage, when the particles to be processed are freshly extruded non-spherical plastic particles (such as strips), due to the high water content (usually in the range of 25% to 70%), the non-spherical particles in the turbulent fluidized state are gradually shaped into a spherical shape during the continuous collision with the grinding rod, other particles and the wall of the cover barrel. In this stage, when the non-spherical plastic particles are relatively moist, the deformation is mainly shaping, and grinding occurs less. In the second stage, as the particles gradually dry from the surface to the inside, the adhesion between the dry outer wall and the particles decreases, and the particles are The particle surface is gradually worn, the edges and corners are further flattened, the mass of a single particle becomes smaller, and the height of the particle is gradually increased in the fluidized bed until it is ground into particles (particles with the required particle size); the ultrafine particle waste produced by particle wear is blown out of the grinding ball device from the top by the fluidized wind and collected by a cyclone or a bag; if only the shaping of non-spherical particles is required (to achieve a certain sphericity), only the first stage can be completed. If the sphericity is not enough, water can be continuously sprayed through the top atomizing nozzle to slow down the drying speed of the plastic body and extend the time of the sphericization (shaping) stage; if the particles are non-plastic bodies after drying, the grinding stage will be directly entered when fluidization begins; this method is applicable to particles of any shape to be processed and has a wide range of applications;

[0032] (2) The grinding method provided by the embodiment of the present invention controls a certain percentage of particles to be blown up higher, thereby causing a faster rate of wear on larger particles. As fluidization continues, larger particles are blown up to a lower height in the fluidized bed (the highest height should not exceed the upper end height of the grinding rod) due to their heavier mass, and thus they will continue to be polished by the grinding rod, resulting in more wear. The mass of the particles gradually decreases as they are polished. However, small particles are blown up to a higher height in the fluidized bed due to their smaller mass, and have more time to be blown above the top of the grinding device. Therefore, small particles are less worn by the grinding rod. On the other hand, large particles shuttle through the narrow gap between the grinding rods, and have more chances to collide with the grinding rods than small particles. Moreover, large particles have a greater weight, so more powder will fall off during grinding. Combining the above reasons, large particles are polished faster and small particles are polished slower, so that the particle size gradually converges during the fluidization process, thereby improving the uniformity of particle size, that is, reducing the span of particle size distribution.

[0033] (3) The ball grinding method provided in the embodiment of the present invention can accurately control the particle size to achieve the target particle size. The fluidized device can be used to take samples at any time during the grinding process (the sampling amount each time is usually in the range of 5 to 20 g). The samples are taken out and the particle size, particle size distribution span and aspect ratio are detected by an image particle size analyzer such as CamSizer. The total time does not exceed 20 minutes. By comparing the detection results with the target, it can be quickly confirmed whether the particles meet the standards. Since the method can achieve a gradual decrease in particle size as the fluidization time increases, sampling detection can be used to quickly detect parameters such as particle size and particle size distribution span. Based on this, the fluidization time can be controlled to fine-tune the particle size. When it reaches the target, the machine can be quickly stopped to achieve accurate control of the particle size and particle size distribution span. This fine-tuning cannot be achieved in the spheronization machine ball making method because the particle mass remains unchanged during the spheronization process.

[0034] (4) The ball grinding method provided by the embodiment of the present invention can avoid the aggregation and adhesion of multiple particles commonly seen in a spheronization machine; during the fluidization process, the extrusion force between the particles is significantly smaller than the extrusion force in the spheronization machine, and the particles are less likely to agglomerate; and the fluidization process will dry the particles from the outside to the inside, and the particles with dry surfaces will not adhere;

[0035] (5) The main parameters of the ball grinding method provided in the embodiment of the present invention can be quantitatively or semi-quantitatively determined by experimental methods. Combined with actual experiments, it has high operability. For example, the air volume affects the particle blowing height, the collision with the grinding rod, the frequency and intensity of friction, etc., which are crucial for obtaining the target particle size, particle size distribution and aspect ratio. Therefore, it needs to be quantitatively set and continuously adjusted during the processing process. The appropriate air volume setting is significantly positively correlated with the average particle size and particle density. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] These and / or other aspects and advantages of the present invention will become apparent and readily understood from the following description of preferred embodiments in conjunction with the accompanying drawings, in which:

[0037] Figure 1 A schematic structural diagram of a fluidized ball grinding device according to an embodiment of the present invention;

[0038] Figure 2 for Figure 1 A schematic structural diagram of a modified example of a fluidized ball grinding device is shown.

[0039] The reference numerals are described as follows:

[0040] 100-Fluidized ball grinding device;

[0041] 10-first screen; 20-cover barrel; 21-truncated cone barrel; 22-cylindrical barrel; 30-grinding rod assembly; 40-second screen; 50-bottom barrel sampler; 60-middle barrel sampler; 70-atomizing nozzle;

[0042] 200-particles to be processed;

[0043] 210 - initial particles to be processed; 220 - larger particles to be processed; 230 - smaller particles to be processed. DETAILED DESCRIPTION

[0044] The features of the present invention are further described below through specific embodiments. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall concept of the present invention and should not be construed as a limitation of the present invention.

[0045] In the present invention, the particle size distribution span is defined as (D 90 -D 10 ) / D 50 (×100%), D is the particle diameter, and the subscript number indicates the percentage of particles smaller than this diameter. The percentage is calculated by volume fraction, the same below; 50 It represents the particle size at which the volume of particles smaller than this particle size accounts for 50% in the particle distribution, and is often called the average particle size. 90 , D 10 and D 50 All of them can be measured using the image particle size analyzer CamS i zer.

[0046] like Figure 1As shown, one embodiment of the present invention provides a fluidized ball grinding device 100, which is used to shape the particles 210 to be processed into spherical shapes and / or grind them into spherical particles with a particle size that meets the target requirements in a fluidized manner. The fluidized ball grinding device 100 includes four main components, namely, a fluidizing device (not shown), a first screen 10, a cover barrel 20, and a grinding rod assembly 30.

[0047] The cover barrel 20 includes two parts, a truncated cone barrel 21 and a cylindrical barrel 22. Specifically, it is composed of the truncated cone barrel 21 and the cylindrical barrel 22 spliced ​​from bottom to top, and of course, it can also include other necessary parts. The outer periphery of the smaller radius end of the truncated cone barrel 21 is connected to the outer periphery of the first screen 10; the grinding rod assembly 30 includes a plurality of grinding rods with rough surfaces, and the plurality of grinding rods are vertically fixed on the first screen 10, and the plurality of grinding rods are higher than the upper plane of the truncated cone barrel 21, but not higher than the upper plane of the cylindrical barrel 22. The fluidization device is used to introduce fluidizing air that causes the particles 200 to be processed (including the initial particles 210 to be processed, the larger particles 220 to be processed, and the smaller particles 230 to be processed) to continuously collide with each grinding rod assembly 30.

[0048] Furthermore, the fluidized ball grinding device 100 may also include a collecting device (not shown) for collecting ultrafine particle waste generated by grinding and blown out from the top of the cylindrical barrel 22 by the fluidizing wind.

[0049] In one embodiment, the first screen 10 is used to prevent the particles 200 to be processed from falling into the bellows below the fluidized device during the grinding process. If the first screen 10 cannot meet the requirement of preventing the particles 200 to be processed from falling into the bellows below the fluidized device during the grinding process, the fluidized ball grinding device 100 can also be provided with a second screen 40 according to the particle size requirement of the particles 200 to be processed. The second screen 40 is provided directly below the first screen 10, and the periphery of the second screen 40 is movably connected to the periphery of the first screen 10. The second screen 40 is a replaceable part, which is used to adapt to the particle size of the target particles, that is, the mesh diameter of the second screen 40 is smaller than the mesh diameter of the first screen 10, that is, it is equivalent to the particle size of the target particles.

[0050] The main specifications of the fluidized ball grinding device 100 used in the embodiment of the present invention are as follows:

[0051] The inner diameter of the bottom of the truncated cone barrel 21 is 10 cm, the inner diameter of the top of the truncated cone barrel 21 is 20 cm, and the height is 18 cm;

[0052] The cylindrical barrel 22 has an inner diameter of 20 cm and a height of 40 cm.

[0053] The fluidized ball grinding device 100 is suitable for particles 200 to be processed within a weight range of 100 to 1500 grams. The first screen 10 is, for example, a 200-mesh stainless steel screen, and the periphery of the first screen 10 is a ring. The collecting device, i.e., the fine powder collecting device, is configured with a primary cyclone and a tail bag. The blown air is room temperature, the maximum blow volume of the fan is about, for example, 2 cubic meters / minute, and the air volume setting range is, for example, 0 to 100. Of course, those skilled in the art should understand that the values ​​of the above parameters can be actually set as needed.

[0054] The grinding rod assembly 30 includes, for example, alternatively, 19 grinding rods are used, and of course the number of grinding rods in the grinding rod assembly 30 can be set as needed. Further, a plurality of grinding rods can be arranged in a hexagon (e.g., a regular hexagon), alternatively, the spacing between two adjacent grinding rods is 0.8 cm, the diameter of each grinding rod is 1.2 cm, and the length is 35 cm. After the grinding rod assembly 30 is installed, the tops of the plurality of grinding rods are higher than the truncated cone barrel 21, but not more than half of the barrel body of the cylindrical barrel 22. The grinding rod closest to the edge of the first screen 10 is 0.4 cm away from the edge of the first screen 10. There are holes drilled in the annulus of the first screen 10, and the truncated cone barrel 21 can be fixedly connected to the first screen 10 with screws. As described above, those skilled in the art can set the specific values ​​of the above parameters as needed, and are not limited to the example values ​​exemplified by the present invention.

[0055] Another embodiment of the present invention provides a ball grinding method using the fluidized ball grinding device 100, comprising the following steps:

[0056] Step 1: Pour the particles 200 to be processed directly into the fluidized ball mill 100, such as the barrel 20, or add them into the fluidized ball mill 100 through a feeder such as an auger or pneumatic conveying.

[0057] Step 2: Introduce fluidizing air of a first air volume to make the particles 200 to be processed begin to fluidize (usually controlled in a turbulent fluidization state). The fluidizing air of the first air volume is used to make the particles 200 to be processed in a turbulent fluidization state and the highest height blown up does not exceed the height of multiple grinding rods. The particles 200 to be processed continuously collide with multiple grinding rods, other particles and the barrel wall of the cover barrel 20. All the particles 200 to be processed gradually transform into a spherical shape until the sphericity of the particles reaches a preset target, thereby obtaining spherical particles.

[0058] The particles 200 to be processed (especially the initial particles 210 to be processed) are usually freshly extruded non-spherical plastic particles. Due to the high water content (usually in the range of 25% to 70%), the non-spherical particles in the turbulent fluidized state are gradually shaped into a spherical shape during the continuous collision with the multiple grinding rod assemblies 30, other particles and the barrel wall of the cover barrel 20, but the volume does not decrease. Figure 2 As shown, in this stage, if the moisture content of the particles 200 to be processed is insufficient, the moisture content of the particles 200 to be processed can be maintained at a certain level by using the atomizing nozzles 70 disposed just above the plurality of grinding rod assemblies 30 .

[0059] In order to determine the air volume setting that can make >99% of the particles blown up to a height lower than the top of the multiple grinding rod assemblies 30, alternatively, the embodiment of the present invention uses the fluidized ball grinding device 100 of the above specifications to conduct an air volume experiment to obtain 104 sets of experimental data. After experimental verification, it is found that the air volume setting (A, range 0-100) that can make >99% of the particles blown up to a height lower than the top of the multiple grinding rod assemblies 30 is related to the average particle size (D 50 , in mm), average bulk density of particles (ρ, in g / cm 3 ) is:

[0060] A=5.29-a+8.73×D 50 +20.0×ρ;

[0061] Among them, A is the air volume, D 50 is the average particle size of the particles 200 to be processed, and ρ is the average bulk density of the particles 200 to be processed.

[0062] The t-test results show that for D 50 The ρ and t statistics are 8.7 and 4.8 respectively, so A and D 50 , ρ were significantly correlated; Adjusted R 2 =0.75, so the setting of A 75% can be determined by the above two parameters.

[0063] In practice, the particles 200 to be processed during the particle fluidization process are relatively dry and have a lower density, so a slightly lower wind speed needs to be set to avoid the particles being blown up too high.

[0064] In the embodiment of the present invention, based on experience, the setting of the first air volume is as follows:

[0065] A 1 =5.29-a+8.73×D 50 +20.0×ρ;

[0066] Among them, A 1 is the first air volume, D 50 is the average particle size of the particles 200 to be processed, ρ is the average packing density of the particles 200 to be processed, and a is a constant greater than 2, and is preferably 3 in this embodiment.

[0067] In addition, the first air volume is also affected by other factors: the larger the aspect ratio of the particles 200 to be processed (the lower the sphericity), the smaller the air volume should be set to, so as to avoid the particles with low sphericity being less polished due to excessively high blowing height; the greater the bed thickness of the particles 200 to be processed (total weight of the particles), the larger the first air volume should be set to, because the thick bed causes greater wind resistance.

[0068] In order to achieve a better particle size screening effect, the small particles are blown up higher than the top of the grinding rod. The air volume should be increased based on the A value obtained above. The more obvious the separation effect is required, the higher the first air volume should be. The influence of these factors on the first air volume setting can also be obtained through empirical formulas combined with actual experimental methods.

[0069] Step 3: After the particles 200 to be processed are shaped into spherical particles, the air volume is increased from the first air volume to the second air volume, and then gradually decreased to the third air volume, in order to keep a preset percentage of the particles 200 to be processed being blown up to a maximum height exceeding the height of the multiple grinding rod assemblies 30.

[0070] like Figure 1 As shown, the smaller particles 230 to be processed have more time to be blown above the top of the fluidized ball grinding device 100 and are less worn by the multiple grinding rod assemblies 30; the smaller particles 220 to be processed are at a lower height in the cover barrel 20 (cannot exceed the upper end height of the multiple grinding rod assemblies 30) and are polished more frequently. The ground ultrafine particle waste produced by particle wear is blown out of the fluidized ball grinding device 100 from the top by the fluidizing wind and collected by a collection device such as a cyclone and / or a bag. In the implementation of the present invention, alternatively, the second air volume, the third air volume and the adjustment speed are all obtained by continuously adjusting the air volume through sampling in combination with the above formula.

[0071] The proportion of particles with height exceeding the top of the plurality of grinding rod assemblies 30 = the sampling weight of the bottom barrel sampler 50 / (the sampling weight of the bottom barrel sampler 50 + the sampling weight of the middle barrel sampler 60 in the same time period) × 100%.

[0072] Step 4: After the particle size of all the particles 200 to be processed reaches the preset target, the fluidizing air is stopped to end the fluidized grinding process, and uniform spherical particles with a small particle size distribution span and a low aspect ratio are obtained.

[0073] The method for judging whether the particle size reaches the preset target in the present invention is: sampling during the grinding process, for example, 5 to 20 g each time, and then detecting the particle size, particle size distribution span and aspect ratio through an image particle size analyzer such as CamS i zer, and the total time does not exceed 5 minutes. By comparing the test results with the target, it can be quickly (within 5 minutes) determined whether the target is met. Alternatively, the bottom barrel sampler 50 and / or the middle barrel sampler 60 are cylindrical hollow tubes that can be pulled out / pushed and rotated, and slotted at the bottom. When sampling, rotate the cylindrical hollow tube 180 degrees so that the slot is upward, and the blown particles can fall into the slot and be collected; pull out the cylindrical hollow tube, rotate the cylindrical hollow tube 180 degrees so that the slot is downward, and the particles can fall out.

[0074] Similar to the above situation, other equipment parameters, such as the size of the grinding rods in the plurality of grinding rod assemblies 30 , the density of the plurality of grinding rods, the gap width, etc., can also be obtained by a similar method.

[0075] Embodiment 1:

[0076] The goal of this embodiment is to use the fluidized ball milling device 100 to obtain uniform spherical particles with an average particle size of 2.7 mm.

[0077] The raw material mass composition for extruding the plastomer is alumina: peanut shell powder pore former: starch: latex: water = 100: 30: 5: 0.5: 78. The water content is 40.3% as determined by a halogen moisture meter (the end point temperature is set at 105°C). After the mixture is fully mixed (mixing time 8 minutes), it is extruded by an extruder through a die with an inner diameter of 3.0 mm to obtain a cylindrical strip plastomer. Corn flour with a particle size of 35 to 60 mesh is used as a dispersant to prevent excessive aggregation and adhesion of the plastomer.

[0078] The cross-sectional diameter and length of 50 strip-shaped plastic bodies were randomly measured using a vernier caliper and d 90 ,d 50 ,d 10 , l 90 , l 50 , l 10 . Where d represents the cross-sectional diameter of the strip plastic body, and the subscript number represents the percentile (the percentage is calculated as a length fraction rather than a volume fraction); for example, d 50 It represents the diameter when the sum of the diameters of particles smaller than this diameter accounts for 50% of the sum of the diameters of all particles; l represents the length of the strip-shaped plastic body, and the subscript number represents the percentile; 50 It represents the length when the sum of the lengths of particles shorter than this length accounts for 50% of the sum of the lengths of all particles. 90 ,d 50 ,d 10 The diameter distribution span is calculated as:

[0079] (d 90 -d 10 ) / d 50 =(3.10-2.81) / 2.96=10%;

[0080] According to l 90 , l 50 , l 10 Calculate the length distribution span:

[0081] (l 90 -l 10 ) / l 50 =(3.42-2.33) / 2.86=38%.

[0082] The strip-shaped plastic body was measured by an image particle size analyzer CamS i zer. 90 , D 50 and D 10 , the particle size distribution span is (D 90 -D 10 ) / D 50 =(3.65-2.82) / 3.32=25%. Where D represents the diameter of the equivalent sphere calculated by the instrument, and the subscript number represents the percentile (the percentage is calculated by volume fraction). The image particle size analyzer also measured an average aspect ratio of 1.23. The aspect ratio is the ratio of the length / width of the circumscribed rectangle of the two-dimensional image of the particle taken by a high-speed camera, which can be used to characterize the degree of deviation of the particle from the true sphere. The closer the value is to 1, the closer the particle morphology is to a sphere.

[0083] In Example 1, under the initial conditions, D 50 3.32 mm, ρ is 0.82 g / cm 3 , according to A 1 =5.29-3+8.73×D 50 +20.0×ρ; we can get A 1 is 48.

[0084] 500 g of the extruded strip plastic body was poured into the bed. The fluidizing air device was turned on to introduce fluidizing air so that the strip plastic body was in a turbulent fluidization state, and the initial air volume was set to 48.

[0085] In the shaping stage (first stage), which is the first 15 minutes of the fluidization process in this embodiment, the strip-shaped plastic bodies all move within a position range lower than the height of multiple grinding rods (the highest position of the strip-shaped plastic bodies does not exceed the top of multiple grinding rods). Since the yellow corn flour is relatively small in size, most of it is carried away by the fluidizing wind in the first minute of the fluidization process. The small part of the corn flour adhering to the plastic particles is also separated from the plastic and carried away by the fluidizing wind during the remaining time as the plastic particles are dried, fluidized and polished. In this stage, it can be observed that the plastic particles are gradually dried, and the strip-shaped plastic body gradually changes into a spherical shape due to the collision. Samples were taken at the end of the plastic stage, and the moisture content of the particles was measured to be 5.3% by a halogen moisture meter, and the average particle size D was measured by an image particle size analyzer. 50 The particle size is 3.35 mm, the particle size distribution span is (3.70-2.92) / 3.35=23%, and the average aspect ratio is 1.11.

[0086] After shaping is completed, the air volume is increased to 58, and the grinding stage (second stage) begins. At this time, about 25% of the particles by weight are blown up to a height that exceeds the top of multiple grinding rods.

[0087] In the remaining 1 hour, the air volume is adjusted to maintain the highest blowing height of 25% of the weight ratio of particles exceeding the top of multiple grinding rods; the air volume is gradually reduced from 58 to 51. During this stage, the particles gradually wear out, and a large number of white smoke-like small particles can be observed in the bed. This is the ultra-fine particle waste produced by particle wear, which is carried out from the top by the fluidizing wind. At the end of 1 hour, the fluidizing wind is stopped, the fluidized grinding process is ended, and the residual powder is sieved out with a sieve. The obtained particles have a water content of 3.3%, an average particle size of 2.91mm, a particle size distribution span of (3.12-2.68) / 2.91=15%, and an average aspect ratio of 1.08. The particles are roasted at 650℃ for 3 hours to obtain the final product of ceramsite. Its average particle size is 2.72mm, the particle size distribution span is (2.90-2.52) / 2.72=14%, and the average aspect ratio is 1.08.

[0088] Embodiment 2:

[0089] The goal of this embodiment is to obtain uniform spherical particles with an average particle size of 6 mm using the fluidized ball milling device 100. The fluidized ball milling device 100 and the raw material composition and dispersant used for extruding the plastic body are the same as those in Example 1, and the plastic body is extruded by an extruder through a die with an inner diameter of 6.2 mm to obtain a strip-shaped plastic body.

[0090] The cross-sectional diameter and length of 50 strip-shaped plastic bodies were randomly measured using a vernier caliper to obtain the diameter distribution span:

[0091] (d 90 -d 10 ) / d 50=(6.49-6.05) / 6.26=7%;

[0092] Length distribution span:

[0093] (l 90 -l 10 ) / l 50 =(7.22-5.25) / 6.22=32%.

[0094] The strip plastic body was measured by the image particle size analyzer CamS i zer and the equivalent sphere particle size distribution span was (D 90 -D 10 ) / D 50 =(7.67-6.40) / 7.07=18%, and the average aspect ratio is 1.20.

[0095] In Example 2, under the initial conditions, D 50 7.07 mm, ρ 0.80 g / cm 3 , the first air volume A can be obtained 1 is 80.

[0096] 500 g of the extruded strip plastic body was poured into the bed. The fluidizing air device was turned on to introduce fluidizing air so that the strip plastic body was in a turbulent fluidization state, and the initial air volume was set to 80.

[0097] In the shaping stage (first stage), which is the first 20 minutes of the fluidization process in this embodiment, the strip-shaped plastic bodies all move within a position range lower than the height of multiple grinding rods (the highest position of the strip-shaped plastic body does not exceed the top of multiple grinding rods). Since the yellow corn flour is relatively small in size, most of it is taken away by the fluidizing wind in the first minute of the fluidization process. The small part of the corn flour adhering to the plastic body particles is also separated from the plastic body and taken away by the fluidizing wind during the remaining time as the plastic body particles are dried, fluidized and polished. In this stage, it can be observed that the plastic body particles are gradually dried, and the strip-shaped plastic body gradually changes to a spherical shape due to the collision. When sampling was performed at the end of the plastic stage, the moisture content of the particles was 10.5%, the particle size distribution span was (7.55-6.46) / 6.99=16%, and the average aspect ratio was 1.12.

[0098] After shaping is completed, the air volume is increased to 95 and the sanding stage (second stage) begins. At this time, about 25% of the particles by weight are blown up to a height that exceeds the top of multiple sanding rods.

[0099] In the remaining 1 hour and 20 minutes, the air volume is adjusted to keep the highest blowing height of the particles with a weight ratio of 25% above the top of multiple grinding rods; the air volume is gradually reduced from 95 to 87. During this stage, the particles gradually wear out, and a large number of white smoke-like small particles can be observed in the bed. This is the ultra-fine particle waste produced by particle wear, which is taken out from the top by the fluidizing wind. After 1 hour and 20 minutes, the fluidizing wind is stopped, the fluidized grinding process is ended, and the residual powder is screened out with a sieve. The obtained particles have a water content of 2.9%, an average particle size of 6.37mm, a particle size distribution span of (6.77-6.00) / 6.371=12%, and an average aspect ratio of 1.09. The particles are roasted at 650°C for 3 hours to obtain the final product of ceramsite. Its average particle size is 5.89mm, the particle size distribution span is (6.23-5.52) / 5.89=12%, and the average aspect ratio is 1.09.

[0100] Embodiment 3:

[0101] The goal of this embodiment is to use the fluidized ball milling device 100 to obtain uniform spherical particles with an average particle size of 0.8 mm.

[0102] The fluidized grinding equipment is the same as that in Example 1. The added particles are dried (water content 4.7%) uncalcined silicon oxide balls with an average particle size D 50 The particle size is 0.978 mm, the particle size distribution span is (1.063-0.881) / 0.978=19%, and the aspect ratio is 1.10.

[0103] 500 grams of small balls are poured into the barrel body of the cover barrel 20 of the fluidized ball grinding device 100. The fluidizing air is turned on and the air volume is set to 31, so that the particles 200 to be processed are in a turbulent fluidized state. During the 30-minute grinding time, the air volume is gradually reduced from 31 to 28 to keep the maximum blowing height of the particles 200 to be processed of about 25% by weight exceeding the top of multiple grinding rods. The fluidizing air is then stopped to end the fluidized grinding process. The particle size distribution span of the obtained particles is (0.924-0.802) / 0.862=14%, and the average aspect ratio is 1.09. The particles are roasted at 650°C for 3 hours to obtain the final product of ceramsite. Its average particle size is 0.820 mm, and the particle size distribution span is (0.872-0.757) / 0.820=14%.

[0104] Comparative Example 1:

[0105] The raw material mass composition for extruding the plastomer is the same as that in Example 1. After the mixture is fully mixed (mixing time 8 minutes), it is extruded by an extruder through a die with an inner diameter of 2.6 mm to obtain a cylindrical strip plastomer. Corn flour with a particle size of 35 to 60 mesh is used as a dispersant to prevent excessive aggregation and adhesion of the plastomer.

[0106] According to d 90 ,d 50 ,d 10 The diameter distribution span is calculated as:

[0107] (d 90 -d 10 ) / d 50 =(2.78-2.48) / 2.63=11%;

[0108] According to l 90 , l 50 , l 10 Calculate the length distribution span:

[0109] (l 90 -l 10 ) / l 50 =(3.27-2.21) / 2.74=39%.

[0110] The strip plastic body was measured by the image particle size analyzer CamS i zer and the equivalent sphere particle size distribution span was (D 90 -D 10 ) / D 50 =(3.40-2.66) / 3.04=24%, and the average aspect ratio is 1.21.

[0111] Add 500 grams of extruded granules to the spheronizer, and add about 20 grams of corn flour with a particle size of 35 to 60 mesh as a dispersant, and spheronize in the spheronizer for 3 minutes until the particles are spherical. The optimal running time of 3 minutes is determined based on experience. When it is observed that the particles have no edges and corners, high sphericity, and no significant aggregation, adhesion, or deformation (such as flattening), the machine can be stopped. The spheronizer can also be stopped every half minute, and the aspect ratio of the obtained particles can be measured with CamS i zer. The total running time corresponding to the minimum aspect ratio is obtained; the optimal running time obtained in this experiment is consistent with the 3-minute running time determined based on experience. The resulting particle size distribution span is (D 90 -D 10 ) / D 50 = (3.34-2.65) / 2.99 = 23%, and the average aspect ratio is 1.12. The obtained particles are dried at 120°C and calcined at 650°C to obtain the final ceramsite product, and its particle size distribution span is (D 90 -D 10 ) / D 50 =(3.13-2.47) / 2.78=24%, and the average aspect ratio is 1.11.

[0112] Comparative Example 2:

[0113] The raw material composition for extruding the plastomer is the same as that in Example 1. After the mixture is fully mixed (mixing time 8 minutes), it is extruded by an extruder through a die with an inner diameter of 2.6 mm to obtain a cylindrical strip plastomer. Corn flour with a particle size of 35 to 60 mesh is used as a dispersant.

[0114] According to d 90 ,d 50 ,d 10 The diameter distribution span is calculated as:

[0115] (d 90 -d 10 ) / d 50 =(5.78-5.31) / 5.58=8%;

[0116] According to l 90 , l 50 , l 10 Calculate the length distribution span:

[0117] (l 90 -l 10 ) / l50=(6.32-4.74) / 5.54=29%.

[0118] The strip plastic body was measured by the image particle size analyzer CamS i zer and the equivalent sphere particle size distribution span was (D 90 -D 10 ) / D 50 =(7.07-5.79) / 6.45=20%, and the average aspect ratio is 1.19.

[0119] Add 500 grams of extruded granules to the spheronizer, and add about 20 grams of corn flour with a particle size of 35 to 60 mesh as a dispersant, and spheronize in the spheronizer for 3 minutes until the granules are spherical. The particle size distribution span of the obtained granules is (D 90 -D 10 ) / D 50 = (7.01-5.85) / 6.49 = 18%, and the average aspect ratio is 1.13. The obtained particles are dried at 120°C and calcined at 650°C to obtain the final product of ceramsite, and the particle size distribution span is (D 90 -D 10 ) / D 50 =(6.61-5.50) / 6.07=18%, and the average aspect ratio is 1.12.

[0120] Comparative Example 3:

[0121] The added particles are dried (water content 4.2%) unbaked silicon oxide balls with an average particle size of D 50The particle size is 0.866 mm, the particle size distribution span is (0.938-0.767) / 0.866=20%, and the aspect ratio is 1.10.

[0122] Add 500 g of the granules to a spheronizer, and add about 20 g of corn flour with a particle size of 35 to 60 mesh as a dispersant, and spheronize in the spheronizer for 3 minutes. The resulting particle size distribution span is (D 90 -D 10 ) / D 50 = (0.943-0.785) / 0.855 = 18%, and the average aspect ratio is 1.09. The obtained particles are dried at 120°C and calcined at 650°C to obtain the final product of ceramsite. Its particle size distribution span is (D 90 -D 10 ) / D 50 =(0.889-0.738) / 0.810=19%, and the average aspect ratio is 1.09.

[0123] As can be seen from Example 1, when the particle size is small (less than 5 mm), the length uniformity of the extruded plastomer is very poor. As can be seen from Example 2, when the particle size becomes larger, the length uniformity of the extruded plastomer is improved. Comparing Example 1 and Example 2, it can be seen that the smaller the particle size of the plastomer, the worse the length uniformity of the extruded plastomer. Conventional ball grinding methods (spheronization machines) are difficult to improve the length uniformity of the plastomer (relative to Comparative Examples 1 and 2), especially for plastomers with relatively small particle sizes.

[0124] By comparing Example 1 with Comparative Example 1, and by comparing Example 2 with Comparative Example 2, it can be seen that the fluidized ball grinding device 100 provided in the embodiment of the present invention can adjust the particle size. During the ball grinding process, D 90 Than D 10 The decrease is greater, indicating that the ball grinding method of this embodiment can selectively grind large particles more, thereby reducing the particle size distribution span and improving the particle size uniformity. The comparison before and after stage 1 in Example 1 and Example 2 can prove that the shaping stage can effectively shape the particles into a spherical shape, achieving a spherical effect similar to that of a spheronization machine. From the comparison between Example 3 and Comparative Example 3, it can be seen that for dried but uncalcined particles, the fluidized ball grinding device 100 can still reduce the average particle size and the particle size distribution span, thereby achieving an improvement in the particle size and particle size uniformity.

[0125] The fluidized ball grinding device and the ball grinding method using the fluidized ball grinding device provided by the embodiments of the present invention have at least one or part of the following advantages:

[0126] (1) The fluidized ball grinding device provided in the embodiment of the present invention adopts a method combining a fluidization process and a grinding rod to achieve shaping (first stage) and grinding (second stage) of the particles to be processed. In the first stage, when the particles to be processed are freshly extruded non-spherical plastic particles (such as strips), due to the high water content (usually in the range of 25% to 70%), the non-spherical particles in the turbulent fluidized state are gradually shaped into a spherical shape during the continuous collision with the grinding rod, other particles and the wall of the cover barrel. In this stage, when the non-spherical plastic particles are relatively moist, the deformation is mainly shaping, and grinding occurs less. In the second stage, as the particles gradually dry from the surface to the inside, the adhesion between the dry outer wall and the particles decreases, and the particles are The particle surface is gradually worn, the edges and corners are further flattened, the mass of a single particle becomes smaller, and the height of the particle is gradually increased in the fluidized bed until it is ground into particles (particles with the required particle size); the ultrafine particle waste produced by particle wear is blown out of the grinding ball device from the top by the fluidized wind and collected by a cyclone or a bag; if only the shaping of non-spherical particles is required (to achieve a certain sphericity), only the first stage can be completed. If the sphericity is not enough, water can be continuously sprayed through the top atomizing nozzle to slow down the drying speed of the plastic body and extend the time of the sphericization (shaping) stage; if the particles are non-plastic bodies after drying, the grinding stage will be directly entered when fluidization begins; this method is applicable to particles of any shape to be processed and has a wide range of applications;

[0127] (2) The grinding method provided by the embodiment of the present invention controls a certain percentage of particles to be blown up higher, thereby causing a faster rate of wear on larger particles. As fluidization continues, larger particles are blown up to a lower height in the fluidized bed (the highest height should not exceed the upper end height of the grinding rod) due to their heavier mass, and thus they will continue to be polished by the grinding rod, resulting in more wear. The mass of the particles gradually decreases as they are polished. However, small particles are blown up to a higher height in the fluidized bed due to their smaller mass, and have more time to be blown above the top of the grinding device. Therefore, small particles are less worn by the grinding rod. On the other hand, large particles shuttle through the narrow gap between the grinding rods, and have more chances to collide with the grinding rods than small particles. Moreover, large particles have a greater weight, so more powder will fall off during grinding. Combining the above reasons, large particles are polished faster and small particles are polished slower, so that the particle size gradually converges during the fluidization process, thereby improving the uniformity of particle size, that is, reducing the span of particle size distribution.

[0128] (3) The ball grinding method provided in the embodiment of the present invention can accurately control the particle size to achieve the target particle size. The fluidized device can be used to take samples at any time during the grinding process (the sampling amount each time is usually in the range of 5 to 20 g). The samples are taken out and the particle size, particle size distribution span and aspect ratio are detected by an image particle size analyzer such as CamSizer. The total time does not exceed 20 minutes. By comparing the detection results with the target, it can be quickly confirmed whether the particles meet the standards. Since the method can achieve a gradual decrease in particle size as the fluidization time increases, sampling detection can be used to quickly detect parameters such as particle size and particle size distribution span. Based on this, the fluidization time can be controlled to fine-tune the particle size. When it reaches the target, the machine can be quickly stopped to achieve accurate control of the particle size and particle size distribution span. This fine-tuning cannot be achieved in the spheronization machine ball making method because the particle mass remains unchanged during the spheronization process.

[0129] (4) The ball grinding method provided by the embodiment of the present invention can avoid the aggregation and adhesion of multiple particles commonly seen in a spheronization machine; during the fluidization process, the extrusion force between the particles is significantly smaller than the extrusion force in the spheronization machine, and the particles are less likely to agglomerate; and the fluidization process will dry the particles from the outside to the inside, and the particles with dry surfaces will not adhere;

[0130] (5) The main parameters of the ball grinding method provided in the embodiment of the present invention can be quantitatively or semi-quantitatively determined by experimental methods. Combined with actual experiments, it has high operability. For example, the air volume affects the particle blowing height, the collision with the grinding rod, the frequency and intensity of friction, etc., which are crucial for obtaining the target particle size, particle size distribution and aspect ratio. Therefore, it needs to be quantitatively set and continuously adjusted during the processing process. The appropriate air volume setting is significantly positively correlated with the average particle size and particle density.

[0131] The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiment. Those skilled in the art will understand that these embodiments can be changed without departing from the principles and spirit of the overall concept of the present invention, and these changes should also be regarded as falling within the protection scope of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A fluidized ball grinding device, characterized in that: The fluidized ball grinding device is used to shape the particles to be processed into spheres and / or grind them into spherical particles in a fluidized manner, and the fluidized ball grinding device comprises: a first screen, the first screen being arranged to be located at a lower portion of the fluidized ball grinding device; A cover barrel, the cover barrel comprising a truncated cone barrel and a cylindrical barrel spliced ​​together, the outer periphery of one end of the truncated cone barrel having a smaller radius is connected to the outer periphery of the first screen; a grinding rod assembly, the grinding rod assembly comprising a plurality of grinding rods with rough surfaces, the plurality of grinding rods being vertically fixedly disposed on the first screen and located in the cover barrel; and A fluidizing device is used to introduce fluidizing air to make the particles to be processed collide with the multiple grinding rods continuously.

2. The fluidized ball grinding device according to claim 1, characterized in that: The combination of the fluidizing device and the grinding rod assembly is used to achieve shaping and grinding of the particles to be processed; The number of the plurality of grinding rods is not less than 10, the plurality of grinding rods are arranged in a hexagonal shape, and the distance between the plurality of grinding rods is 0.2 to 3 cm. The plurality of grinding rods are higher than the upper end plane of the truncated cone barrel, but do not exceed the upper end plane of the cylindrical barrel.

3. The fluidized ball grinding device according to claim 2, characterized in that: The plurality of grinding rods are higher than the height of the truncated cone barrel but not more than 3 / 4 of the height of the cylindrical barrel; The fluidized ball grinding device also includes a second screen, which is arranged directly below the first screen, and the periphery of the second screen is movably connected to the periphery of the first screen; the second screen is used to prevent the particles to be processed from falling into the fluidized device.

4. The fluidized ball grinding device according to claim 1, characterized in that: The volume of fluidizing air introduced into the fluidizing device is a first volume that allows the particles to be processed to reach a preset target sphericity, so that the highest height of the particles to be processed blown up does not exceed the height of multiple grinding rods.

5. The fluidized ball grinding device according to claim 4, characterized in that: The fluidized ball milling device allows the particles to be processed to undergo a first stage and a second stage. In the first stage, the particles to be processed are wet non-spherical plastic particles, and the fluidizing device causes the non-spherical plastic particles to gradually be shaped into a spherical shape during the continuous collision with the multiple grinding rods and the barrel wall under the turbulent fluidization state; In the second stage, as the particles to be processed dry from the surface to the inside, the surface of the particles to be processed gradually wears away, the mass of a single particle to be processed decreases, and the height of the particles blown in the fluidizing device gradually increases until ground particles are produced. The water content of the particles to be treated is 25% to 70%.

6. The fluidized ball grinding device according to claim 5, characterized in that: The fluidized ball grinding device also includes an atomizing nozzle arranged directly above the plurality of grinding rods, and the atomizing nozzle is used to spray water from the top of the fluidized ball grinding device into the cover barrel when the sphericity of the ground particles does not reach the expected target, so as to slow down the drying speed of the particles to be processed and prolong the shaping time; The fluidizing device dries the particles to be processed from the outside to the inside during the fluidizing process, so that the particles to be processed with dry surfaces will not be adhered.

7. The fluidized ball grinding device according to any one of claims 4 to 6, characterized in that: The first air volume is calculated according to the following formula: A1=5.29-a+8.73×D 50 +20.0×ρ; Among them, A1 is the first air volume, D 50 is the average particle size of the particles to be treated, ρ is the average bulk density of the particles to be treated, a is a constant greater than 2, The larger the aspect ratio of the particles to be processed is, the smaller the first air volume is set to be; The greater the bed thickness of the particles to be processed, the greater the first air volume is set to.

8. The fluidized ball grinding device according to claim 7, characterized in that: The proportion of particles to be processed whose height exceeds the top of multiple grinding rods = sampling weight of bottom barrel sampler / (sampling weight of bottom barrel sampler + sampling weight of middle barrel sampler in the same time interval) × 100%, wherein the bottom barrel sampler takes samples from the bottom of the cover barrel, and the middle barrel sampler takes samples at a height higher than multiple grinding rods in the cover barrel.

9. The fluidized ball grinding device according to claim 8, characterized in that: The fluidizing device continuously adjusts the air volume of the fluidizing air to keep a preset percentage of the particles to be processed being blown up to a maximum height exceeding the height of multiple grinding rods; and stops the fluidizing air after the particles to be processed meet the preset particle size target. The preset percentage is 20% to 30%.

10. The fluidized ball grinding device according to claim 9, characterized in that: In order to continuously adjust the air volume of the fluidizing air, the fluidizing device first increases the air volume to the second air volume, and then gradually decreases it to the third air volume; The fluidized ball grinding device may further include a collecting device for collecting ultrafine particle waste generated by grinding and blown out from the top of the cylindrical barrel by the fluidized wind.

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