A system and method for preparing graded ultrafine particles using high elastic material

Abstract

The present invention relates to a system and method for preparing graded ultrafine particles using a highly elastic material, comprising the following steps: pre-expanding coarse particles of the highly elastic material using high-pressure gas to obtain expanded material coarse particles; surface-modifying the expanded material coarse particles to obtain modified coarse particles; suspending the modified coarse particles in a liquid and shear-crushing them to obtain ultrafine mixed particles; and grading the ultrafine mixed particles to obtain graded ultrafine particles. The present invention utilizes high-pressure gas permeation expansion to produce ultrafine particles, achieving a uniform particle size distribution after crushing. This method eliminates the need for ultra-low temperature cooling, such as with liquid nitrogen, and effectively reduces energy consumption. The surface of the highly elastic material is modified to enable suspension in a liquid, facilitating efficient, constant-temperature, and continuous high-shear crushing at temperatures below the material's failure point.

Description

Technical Field

[0001] The invention relates to the field of high-elasticity material crushing, and in particular to a system and method for preparing graded ultrafine particles using high-elasticity materials. Background Art

[0002] Highly elastic materials are usually crushed mechanically. The main crushing methods are as follows: room temperature crushing method, low temperature freezing crushing method, organic solvent immersion expansion crushing method, etc.

[0003] (1) Room temperature pulverization method: High elastic materials are pulverized mechanically at room temperature. The product has low particle size, large particle size distribution, high labor intensity, high processing cost, and is an open production process. Dust is difficult to control and pollution is serious.

[0004] (2) Low-temperature pulverization: Low-temperature pulverization is to use liquid nitrogen freezing or other methods to cool the highly elastic material to below the glass transition temperature, and then mechanically pulverize it. This method has high energy consumption, a large particle size distribution of the product, and low production capacity.

[0005] (3) Organic solvent immersion and crushing method: This method uses solvent to swell the high-elastic material ground into a certain particle size, and then crushes it to make rubber powder. This method has high energy consumption, solvent volatilization and secondary pollution, and the production process has flammable and explosive safety hazards, and low production capacity. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above technical deficiencies and provide a system and method for preparing graded ultrafine particles using high elastic materials, so as to solve the technical problems in the prior art of low particle size, large particle size distribution and high energy consumption after crushing high elastic materials.

[0007] In order to achieve the above technical objectives, the technical solution provided by the present invention is:

[0008] In a first aspect, the present invention provides a method for preparing graded ultrafine particles using a highly elastic material, comprising the following steps: pre-expanding coarse particles of the highly elastic material using a high-pressure gas to obtain coarse particles of the expanded material; surface-modifying the coarse particles of the expanded material to obtain modified coarse particles; suspending the modified coarse particles in a liquid for shear crushing to obtain ultrafine mixed particles; and grading the ultrafine mixed particles to obtain graded ultrafine particles.

[0009] In a second aspect, the present invention provides a system for preparing graded ultrafine particles using a high-elastic material, comprising a pre-expansion unit, a surface property modification unit, a shearing and crushing unit, and a particle size grading unit arranged in sequence, wherein: the pre-expansion unit comprises a sealed tank, on which a high-pressure gas inlet and outlet are provided, for allowing the high-pressure gas to penetrate into the coarse particles of the high-elastic material, and after the penetration equilibrium, the pressure is released to obtain the coarse particles of the expanded material; the surface property modification unit is used to perform surface modification on the coarse particles of the expanded material to obtain modified coarse particles with a hydrophilic surface; the shearing and crushing unit comprises a shearing and crushing tank body, in which a liquid is contained, and the liquid is used to suspend the modified coarse particles to be crushed; a shearing and crushing device is provided at the bottom of the shearing and crushing tank body, and the shearing and crushing device is used to shear and crush the modified coarse particles to obtain ultrafine mixed particles; the particle size grading unit is used to grade the ultrafine mixed particles to obtain graded ultrafine particles.

[0010] Compared with the prior art, the present invention has the following beneficial effects:

[0011] (1) The high-pressure gas infiltration expansion method of the high-elastic material is used to pre-expand the high-elastic material in the pre-expansion unit. The same crushing method can be used to obtain high-elastic material particles with higher mesh size. After the crushing, the high-pressure gas in the particles is discharged and the particles are reduced. The preparation of ultrafine particles is achieved through the dual action, and the particle size distribution after crushing is uniform. No ultra-low temperature cooling such as liquid nitrogen is required, which effectively reduces energy consumption.

[0012] (2) The present invention modifies the surface of the coarse particles of the expansion material so that they can be suspended in the liquid with a hydrophilic surface, thereby facilitating efficient constant temperature continuous high shear crushing of the highly elastic material in the shear crushing unit at a temperature lower than the material's failure temperature;

[0013] (3) The present invention crushes the high elastic material in liquid, avoiding the adverse effects of excessive temperature on the material and the phenomenon of high elastic material melting and sticking to the blade; at the same time, no organic solvent soaking is required, effectively avoiding secondary pollution.

[0014] Furthermore, the present invention adopts fluid speed control, which can bring ultrafine particles within the qualified particle size range out of the shear crushing unit for classification, thereby realizing continuous production; the fluid discharged from the particle size classification unit is filtered, and the resulting clear liquid and particles with a particle size larger than the qualified range are returned to the shear crushing unit to form a cycle, which can effectively reduce the crushing load, maintain the total liquid flow rate basically unchanged, and effectively reduce energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural diagram of the system of the present invention;

[0016] Figure 2 It is a structural schematic diagram of the pre-expansion unit in the system of the present invention;

[0017] Figure 3Schematic diagram of the structure of the surface property modification unit in the system of the present invention;

[0018] Figure 4 Schematic diagram of the structure of the shear crushing unit in the system of the present invention;

[0019] Figure 5 It is a schematic structural diagram of the particle size classification unit in the system of the present invention;

[0020] Figure 6 It is a schematic flow diagram of the method of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0022] The present invention provides a system and method for preparing graded ultrafine particles using a high elastic material, in particular, capable of producing high elastic material ultrafine particles with controllable graded particle sizes at low cost.

[0023] See also Figure 1 The system of the present invention comprises a pre-expansion unit 1, a surface property modification unit 2, a shearing and crushing unit 3 and a particle size classification unit 4, which are arranged in sequence, wherein:

[0024] See also Figure 2 The pre-expansion unit 1 is used to allow high-pressure gas to penetrate into the coarse particles of high-elastic material, causing their volume to expand, and to release the pressure after the penetration equilibrium to obtain the coarse particles of expanded material; it includes a sealed tank body 101, which is provided with a high-pressure gas inlet 102, a pressure relief port, and a material inlet and outlet.

[0025] See also Figure 3 The surface property modification unit 2 is used to modify the hydrophobic properties of the surface of the coarse particles of the expanded material so that the coarse particles of the expanded material form a surface hydrophilic material; the surface property modification unit 2 includes a modification tank body 201, on which a modification reagent inlet 202, an expansion material coarse particle inlet 203 and a modified coarse particle outlet 204 are provided, and an agitator 205 is provided in the modification tank body 201.

[0026] See also Figure 4 The shearing and crushing unit 3 is used to shear and crush the modified coarse particles, and preferably adopts a high-efficiency constant temperature continuous high shearing and crushing unit; the shearing and crushing unit 3 includes a shearing and crushing tank body 301, and a shearing and crushing device is arranged at the bottom of the shearing and crushing tank body 301; a liquid inlet 302 is arranged on the bottom or lower side wall of the shearing and crushing tank body 301, and a liquid outlet 303 is arranged on the top or upper side wall of the shearing and crushing tank body 301, so that the liquid forms a fluid that enters from the bottom and exits from the top.

[0027] Among them, those skilled in the art can easily select a shearing and crushing device according to the situation, such as a device with a single-head or multi-head blade, etc., as long as it can achieve rotary shearing and crushing, and no specific limitation is made here.

[0028] In the present invention, the "upper part" refers to the part between the center position and the top of the device.

[0029] See also Figure 5 The particle size classification unit 4 is used to classify the high elastic material after shear crushing; it is preferred to adopt an energy-saving and consumption-reducing stepped particle size ultrafine particle classification unit; it includes a multi-stage separation tank, and a product outlet is opened on the top or upper side wall of each stage particle size separation tank to communicate with the next stage separation tank, and the connecting port is located on the side wall of the next stage separation tank; a product outlet is opened on the bottom or lower side wall of each stage particle size separation tank, and each stage separation tank of the particle size classification unit 4 has a liquid with a decreasing upward flow rate gradient; the liquid of the particle size classification unit 4 is filtered and returned to the shear crushing unit 3 to form a circulation loop.

[0030] Taking the three-stage separation tank as an example, it includes a primary separation tank 41, an intermediate separation tank 42 and a final separation tank 43, wherein an outlet 411 is provided on the top or upper side wall of the primary separation tank 41, an inlet 412 is provided on the side wall, and an outlet 413 is provided on the bottom or lower side wall, wherein the inlet 412 is located between the outlets 411 and 413, preferably located on the lower side wall of the primary separation tank 41; similarly, three inlets and outlets (421-423, and 431-433) are respectively provided on the intermediate separation tank 42 and the final separation tank 43, wherein the products separated by the outlets 411 and 421 go to the next stage separation tank, the outlet 413 obtains the product with a particle size of D1 or directly returns to the shear crushing unit, the outlet 423 obtains the product with a particle size of D2, the outlet 433 obtains the product with a particle size of D3, and the outlet 431 obtains the product with a particle size of D4, that is, as the final separation unit, the upper product outlet of the final separation tank 43 also directly collects the product particles; and the particle sizes D1 to D4 decrease successively.

[0031] The liquid flow rate in the shearing and crushing tank 301 is v1, the liquid flow rate in the primary separation tank 41 is v2, the liquid flow rate in the intermediate separation tank 42 is v3, and the liquid flow rate in the final separation tank 43 is v4, v1>v2>v3>v4.

[0032] The number of intermediate separation tanks 42 can be multiple, such as two, three, four or even more, according to the particle size range to be separated.

[0033] The liquid outlet 303 is connected to the inlet 412 on the primary separation tank 41. The liquid discharged from the outlets 413, 423, 433 and 431 is filtered to separate the ultrafine particles, and the clear liquid returns to the liquid inlet 302 to form a circulation loop, so that the total liquid flow rate remains basically unchanged and can be recycled; the liquid enters the shearing and crushing tank body 301 through the liquid inlet 302 and is discharged from the liquid outlet 303, so that the liquid flows upward as a whole in the shearing and crushing tank body 301. By controlling the liquid flow rate, the crushed small-particle high-elastic material is brought out and enters the particle size classification unit 4 for classification; the liquid flow rate is also controlled in the particle size classification unit 4 to achieve ultrafine mixed particle classification, and the particle size of the ultrafine particles discharged from the upper part is smaller than the particle size of the ultrafine particles in the lower part. The ultrafine particles in the lower part can be collected (qualified products) or directly returned to the shearing and crushing unit (unqualified large particle products) according to actual conditions.

[0034] In some specific embodiments, the liquid in the particle size classification unit 4 is filtered, and the resulting clear liquid returns to the shearing and crushing unit 3 to form a circulation loop; depending on the test situation, a cooling unit can also be set on the clear liquid pipeline returning to the shearing and crushing unit to maintain the temperature of the shearing and crushing unit at around room temperature.

[0035] See also Figure 6 The method of the present invention mainly comprises the following steps:

[0036] S1) the coarse particles of the high elastic material enter the high elastic material high pressure gas pre-expansion unit: the high elastic material coarse particles are pre-expanded with high pressure gas to obtain expanded material coarse particles;

[0037] A container with a pressure resistance of 5 to 10 MPa is designed, in which coarse particles of a high-elastic material are placed for high-pressure gas infiltration. After the high-pressure gas infiltrates into the coarse particles of the high-elastic material and reaches equilibrium, the pressure is usually increased and maintained for 20 to 40 minutes. When the pressure is then reduced to ambient atmospheric pressure, the volume of the high-elastic material expands by 3 to 5 times, thereby obtaining expanded coarse particles of the material.

[0038] S2) the coarse particles of the expanded material enter a surface property modification unit: the surface of the coarse particles of the expanded material is modified to obtain modified coarse particles;

[0039] Specifically, the surface hydrophobicity of the coarse particles of the expansion material is changed to hydrophilicity by using modifiers such as surfactants, defoaming agents and dispersants to obtain modified coarse particles;

[0040] S3) The modified coarse particles enter a high-efficiency constant-temperature continuous high-shear crushing unit: the modified coarse particles are suspended in a liquid and shear-crushed to obtain ultrafine mixed particles;

[0041] Specifically, the modified coarse particles are suspended in a high heat capacity heat-carrying fluid to achieve efficient constant temperature continuous high shear crushing of the modified coarse particles to obtain ultrafine mixed particles;

[0042] S4) the ultrafine mixed particles enter a particle size classification unit: the ultrafine mixed particles are classified to obtain graded ultrafine particles;

[0043] Specifically, the ultrafine mixed particles obtained by crushing the high elastic material by the shear crushing unit are classified according to the process requirements through the stepped particle size classification units with different upward flow rates to obtain stepped ultrafine particles of high elastic material in a specific particle size range.

[0044] Preferably, in step S3) and step S4), the fluid rising speed is adjusted according to the particle size of the final classified product until the particle size meets the requirements of each classification.

[0045] Preferably, the surfactant is one or more of silane coupling agent KH-550, AES (sodium fatty alcohol polyoxyethylene ether sulfate), and LAS (linear alkylbenzene sulfonate), with the dosage being 1‰ to 15‰, more preferably 5‰ to 15‰. The defoamer is a silicone defoamer, and the dispersant is NNO (sodium methylene dinaphthalene sulfonate) or polycarboxylic acid, both with the dosage being 1‰ to 5‰.

[0046] Preferably, the highly elastic material includes one or more of rubber and plastic, such as nitrile rubber, styrene-butadiene rubber, PU or PVC.

[0047] Preferably, the high heat capacity heat-carrying fluid includes water, salt solution or colloidal solution; wherein the salt or colloid is used to adjust the fluid density and the carrying capacity, so as to better control the sedimentation rate of the highly elastic material particles; water is used as the main solvent, which has a low boiling point (highest heat capacity) to ensure that the relevant properties of the elastic material are not damaged.

[0048] More preferably, the salt in the salt solution is one or more of sodium chloride, potassium chloride, and ammonium sulfate; and the colloid is one or more of xanthan gum, CMC, and polyacrylamide. The specific concentrations can be adjusted according to the desired product particle size during actual production.

[0049] Preferably, the high-pressure gas includes nitrogen and carbon dioxide, or a mixture of the two in any proportion.

[0050] The main mechanism of action and advantages of the present invention are:

[0051] (1) The high-pressure gas infiltration expansion method of the high-elastic material is used to pre-expand the high-elastic material in the pre-expansion unit, so that the volume of the high-elastic material expands 3-5 times before entering the crushing unit. The same crushing method can be used to obtain high-elastic material particles with a higher mesh size. After the expanded material is sheared and crushed, the balanced gas in it will be released, further reducing the particle size of the final product. The dual effect obtains ultrafine particles with a minimum particle size of about 6.5μm, effectively reducing energy consumption;

[0052] (2) Changing the hydrophobic properties of the surface of the high elastic material in the surface property modification unit so that it can be suspended in a high heat capacity heat-carrying fluid with a hydrophilic surface, thereby facilitating efficient constant temperature continuous high shear crushing of the high elastic material in the shear crushing unit at a temperature lower than the material's failure temperature;

[0053] (3) Certain high elastic materials have a fixed density. When the particle diameter is small, the Stokes formula is used to approximate the settling velocity of solid particles in liquid:

[0054]

[0055] in:

[0056] Vt: particle settling velocity;

[0057] ρs: particle density;

[0058] ρ: liquid density;

[0059] μ: liquid viscosity;

[0060] g: acceleration due to gravity;

[0061] d: particle equivalent diameter.

[0062] The sedimentation velocity Vt of particles of a certain diameter in a liquid can be calculated. Therefore, in a system such as a shear crushing unit, the velocity Vu of the upward flow of the liquid is controlled to be slightly greater than or equal to the sedimentation velocity Vt of particles of a certain specific diameter di in the liquid. Then, the sedimentation velocity Vti of all particle groups ∑ρi with diameters less than or equal to this specific diameter di in the liquid is less than the velocity of the upward flow of the liquid. As a result, the ∑ρi particle group is carried out by the liquid flowing upward at a velocity Vu in the shear crushing unit and enters a stepped distribution of particle size classification units with a decreasing upward flow velocity gradient. The particle size classification units use the same principle to classify particles. In this cycle, a series of highly elastic materials with graded particle sizes are obtained, realizing the low-energy preparation of graded ultrafine particles. Particles with a diameter greater than the specific diameter di have a net downward velocity because their sedimentation velocity is greater than the upward flow velocity Vu of the liquid, and they gather at the bottom of the system. They are further recovered according to the particle size, or enter the shear crushing unit for efficient, constant-temperature, continuous high-shear crushing, and repeat the cycle. This method can greatly reduce the workload of the constant temperature continuous high shear crushing unit; therefore, a stepped distribution of particle size classification units with different upward flow rates is used to classify the ultrafine mixed particles of high elastic materials that have been crushed by the shear crushing unit into stepped ultrafine particles of high elastic materials in a specific particle size range according to process requirements.

[0063] The present invention is further described in detail below through specific examples and comparative examples.

[0064] Example 1

[0065] Rubber is difficult to crush. Traditionally, only liquid nitrogen cooling can achieve the goal of crushing to a smaller particle size. However, liquid nitrogen heats up quickly, resulting in high costs and energy consumption, making it unsuitable for large-scale production. Conventional mechanical crushing is completely ineffective and may even cause the temperature to rise, leading to rubber melting. The following steps are used to process large rubber particles:

[0066] (1) placing rubber coarse particles with a particle size of 40-60 mesh in a high-pressure gas pre-expansion unit, introducing high-pressure nitrogen, controlling the pressure between 5 and 10 MPa, and reducing the pressure to atmospheric pressure after 30 minutes, and the volume of the rubber coarse particles expands by 4 times to obtain expanded rubber coarse particles;

[0067] (2) adding 10‰ of the mass of the expanded rubber coarse particles of surfactant KH-550, 2‰ of a silicone defoamer, and 2‰ of a dispersant NNO to the expanded rubber coarse particles, and mixing them uniformly to obtain modified rubber coarse particles;

[0068] (3) The modified rubber coarse particles are fed into a shear crushing unit at a shear speed of 10,000 to 15,000 r / min to obtain ultrafine mixed particles with a particle size of 800 to 2,000 mesh; the ultrafine mixed particles are classified to obtain graded ultrafine particles, and the particle size limits of the graded products can be set to 800 mesh, 1,000 mesh, 1,500 mesh, and 2,000 mesh (6.5 μm).

[0069] Example 2

[0070] The large particles of PU were treated using the same steps and conditions as in Example 1.

[0071] The results were the same as those in Example 1, and ultrafine mixed particles with a particle size of 800 to 2000 meshes were finally obtained.

[0072] Example 3 (Investigating the influence of different surfactant dosages)

[0073] Example 3 is basically the same as Example 1, except that the amount of surfactant is adjusted to 0, 1‰, 5‰, 15‰ and 20‰ respectively, and the other steps and conditions are the same as Example 1.

[0074] The results showed that: when no surfactant was used (the dosage was 0), the surface of the rubber coarse particles was not modified, resulting in them being non-hydrophilic. Due to the hydrophobic effect (with bubbles), they floated on the liquid surface and could not be suspended in the liquid, which was not conducive to shear crushing to obtain ultrafine particles; when the surfactant dosage was 1‰, the rubber coarse particles were not completely uniformly dispersed. When it was 5‰ to 15‰, the rubber coarse particles changed from incomplete suspension to uniform suspension. After exceeding 15‰, the suspension state of the rubber coarse particles did not change significantly. Considering the cost, the preferred surfactant dosage of the present invention is 5‰ to 15‰.

[0075] Example 4 (Investigating the influence of expansion ratio)

[0076] Example 4 is the same as Example 1, except that the pressure and time of the high-pressure gas are controlled so that the volume of the rubber coarse particles expands by 0 times (normal pressure gas), 2 times, 3 times and 5 times, respectively. The other steps and conditions are the same as Example 1.

[0077] The results showed that: when the volume does not expand or expands too little, such as 2 times, it cannot effectively promote the final shear crushing into ultrafine particles, and the particle size of the product obtained under the same processing conditions is larger than that of Example 1; after extending the crushing time, the particle size distribution of the obtained product is also mainly concentrated in the range of larger particles (indicating that simply extending the crushing time cannot achieve the purpose of obtaining ultrafine particles); when the pressure is too high, the requirements for the container are high, the energy consumption is high, and the maximum expansion multiple of the rubber coarse particles is basically five times. Continuing to increase the pressure or extending the pressure maintenance time is not conducive to saving energy consumption. Therefore, the present invention preferably expands the volume of the high elastic material by 3 to 5 times.

[0078] Comparative Example 1

[0079] The order of step (1) and step (2) is reversed, that is, modification is performed first and then pre-expansion is performed. The other steps and conditions are the same as those in Example 1.

[0080] The results showed that the highly elastic material was first modified and then pre-expanded. The pre-expansion increased the specific surface area of ​​the rubber coarse particles, and there were unmodified areas on the surface, resulting in uneven suspension in the liquid.

[0081] Similarly, the defoaming agent and dispersant used in the present invention both help the highly elastic material to be evenly suspended in the liquid, which is beneficial for shearing, crushing and particle classification.

[0082] The present invention crushes the high elastic material in a constant temperature liquid, avoids the adverse effect of excessive temperature on the material, and prevents the high elastic material from melting and sticking to the blade; at the same time, the liquid flow rate is controlled, and the qualified ultrafine particles can be taken out of the shear crushing unit for classification, thereby realizing continuous production.

[0083] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for preparing graded ultrafine particles using a highly elastic material, characterized in that: The following steps are involved: High-pressure gas is used to pre-expand coarse particles of a highly elastic material to obtain coarse particles of expanded material; The coarse particles of the expansion material are surface-modified by using a surfactant, a defoaming agent and a dispersant to change the hydrophobic properties of the surface of the coarse particles of the expansion material to hydrophilic properties, thereby obtaining modified coarse particles; The modified coarse particles are suspended in a liquid and sheared and crushed to obtain ultrafine mixed particles; the liquid includes water, a salt solution or a colloidal solution, and the salt solution or the colloidal solution uses water as a main solvent; The ultrafine mixed particles are classified to obtain graded ultrafine particles.

2. The method for preparing graded ultrafine particles using a highly elastic material according to claim 1, wherein: The surface modification is to add 1‰ to 10‰ of the mass of the coarse particles of the expansion material to the coarse particles of the expansion material, 1‰ to 5‰ of the defoaming agent and 1‰ to 5‰ of the dispersant and mix them evenly.

3. The method for preparing graded ultrafine particles using a highly elastic material according to claim 2, wherein: The surfactant is one or more of KH-550, AES and LAS; the defoaming agent is a silicon-based defoaming agent; and the dispersant is NNO or polycarboxylic acid.

4. The method for preparing graded ultrafine particles using a highly elastic material according to claim 1, wherein: The high elastic material includes one or more of rubber and plastic; the pressure of the high pressure gas is 5 to 10 MPa, and the pre-expansion volume expansion multiple is 3 to 5 times.

5. The method for preparing graded ultrafine particles using a highly elastic material according to claim 1, wherein: The particle size of the coarse particles of the high elastic material is between 40 and 60 meshes; the particle size of the ultrafine mixed particles is between 800 and 2000 meshes.

6. The method for preparing graded ultrafine particles using a highly elastic material according to claim 1, wherein: The ultrafine mixed particles are classified by sieving or placed in a liquid for classification.

7. The method for preparing graded ultrafine particles using a highly elastic material according to claim 6, characterized in that: The liquid used in shear crushing and the liquid used in classification are both upward-flowing fluids. The upward flow velocity of the fluid is Vu, and the sedimentation velocity of the ultrafine mixed particles in the liquid is Vt. The ultrafine mixed particles with Vt < Vu enter the next level of classification with the fluid; the ultrafine mixed particles with Vt ≥ Vu are recovered or returned to the shear crushing step.

8. A system for preparing graded ultrafine particles using highly elastic materials, characterized in that: It includes a pre-expansion unit, a surface property modification unit, a shearing and crushing unit and a particle size classification unit, which are arranged in sequence, wherein: The pre-expansion unit includes a sealed tank with a high-pressure gas inlet and outlet provided on the sealed tank for allowing the high-pressure gas to penetrate into the coarse particles of the high-elasticity material, and after the penetration equilibrium is reached and the pressure is released, the coarse particles of the expanded material are obtained; The surface property modification unit is used to perform surface modification on the coarse particles of the expansion material to obtain modified coarse particles with a hydrophilic surface; The shearing and crushing unit includes a shearing and crushing tank body, which is filled with liquid for suspending the modified coarse particles to be crushed; a shearing and crushing device is provided at the bottom of the shearing and crushing tank body, which is used to shear and crush the modified coarse particles to obtain ultrafine mixed particles; the liquid includes water, salt solution or colloidal solution, and the salt solution or colloidal solution uses water as the main solvent; The particle size classification unit is used to classify the ultrafine mixed particles to obtain graded ultrafine particles.

9. The system for preparing graded ultrafine particles using a highly elastic material according to claim 8, characterized in that: The particle size classification unit includes a primary separation tank, a secondary separation tank, and a final separation tank, all of which are filled with liquid; the liquids are all fluids that enter from the bottom and exit from the top; and the flow rate of the fluid in the shear crushing tank, the primary separation tank, the secondary separation tank, and the final separation tank decreases gradually; the fluid discharged from the particle size classification unit is filtered, and the resulting clear liquid is cooled and returned to the shear crushing unit to form a cycle.

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