Method for producing large-particle spherical packing abrasive and large-particle spherical packing abrasive

Abstract

The present application relates to the technical field of accumulation abrasive, and particularly relates to a preparation method of large-particle spherical accumulation abrasive and the large-particle spherical accumulation abrasive, which comprises the following steps: mixing abrasive powder, a binder, a dispersing agent and a solvent to prepare slurry, and preparing small-particle spherical abrasive matrix by using a spray granulation process; putting the small-particle spherical abrasive matrix into a roller agglomeration device, and spraying coating slurry containing abrasive powder into the roller agglomeration device, so that the small-particle spherical abrasive matrix is gradually coated and grown in a layer-by-layer manner to form large-particle spherical accumulation particles in a rolling agglomeration process; synchronously performing infrared dynamic drying on the large-particle spherical accumulation particles in the rolling agglomeration process, so that the coating layer is gradually solidified and a stable accumulation structure is formed; and performing post-treatment and screening on the particles after the roller agglomeration and the infrared dynamic drying, so as to obtain large-particle spherical accumulation abrasive with a target particle size range. The present application is beneficial to improving the structural integrity and the interlayer bonding stability of the particles.

Description

Technical Field

[0001] This invention relates to the field of abrasive packing technology, and in particular to a method for preparing large-particle spherical abrasive packing and the large-particle spherical abrasive packing. Background Technology

[0002] Abrasives are widely used in precision grinding, polishing, and surface finishing. Their particle morphology, size distribution, and structural strength directly affect processing efficiency, surface quality, and operational stability. Currently, most abrasive particles are irregularly shaped, resulting in poor flowability, insufficient dispersion, and inconsistent processing. In contrast, spherical abrasives exhibit better flowability and uniform filling properties, thus showing promising application prospects in precision machining.

[0003] Existing methods for preparing spherical abrasives often employ a one-step spray drying process to directly form spherical particles. While this method can produce spherical particles, it typically struggles to achieve layer-by-layer growth and structural densification. The resulting particles are mostly homogeneous with limited interlayer bonding, and there is still room for improvement in particle size control precision and sphericity stability. Furthermore, traditional hot air drying methods are prone to problems such as excessively rapid surface drying and excessive internal moisture retention during particle drying, which negatively impacts particle strength and final performance. Therefore, there is an urgent need for a packing abrasive that can achieve layer-by-layer coating growth, improve structural density, enhance sphericity and particle size uniformity, and improve particle strength and flowability. Summary of the Invention

[0004] To address the aforementioned issues, this invention first obtains a small-diameter spherical abrasive matrix through spray granulation, and then, during the drum agglomeration process, progressively coats the matrix with a slurry containing abrasive powder, layer by layer, in conjunction with simultaneous infrared dynamic drying. This process ensures that the particles do not form a homogeneous structure through a single-step spherical formation, but rather form a stacked shell structure with the spherical matrix as the core and the outer layers growing progressively. This method is beneficial for improving the integrity of the particle structure and the stability of interlayer bonding, thus providing a method for preparing large-particle spherical stacked abrasives.

[0005] The technical solution adopted in this invention is: a method for preparing large-particle spherical abrasive, comprising the following steps:

[0006] S1. Abrasive powder, binder, dispersant and solvent are mixed to form a slurry, and small-diameter spherical abrasive matrix is ​​prepared by spray granulation process; S2. The small-diameter spherical abrasive matrix is ​​put into the roller agglomeration device, and a coating slurry containing abrasive powder is sprayed into the roller agglomeration device, so that the small-diameter spherical abrasive matrix grows layer by layer during the rolling agglomeration process to form large spherical aggregated particles. S3. During the rolling agglomeration process, the large spherical stacked particles are simultaneously subjected to infrared dynamic drying, so that the coating layer gradually solidifies and forms a stable stacked structure. S4. The particles after drum agglomeration and infrared dynamic drying are post-processed and sieved to obtain large-particle spherical abrasive within the target particle size range.

[0007] A further improvement to the above scheme is that, in step S1, the solid content of the slurry is 20%-50%, and the spray granulation process adopts a two-fluid atomization method with an atomization pressure of 0.3-0.8 MPa and an atomization angle of 60-120°.

[0008] A further improvement to the above scheme is that a temperature gradient is set along the material flow direction in the drying tower of spray granulation, with the inlet temperature being 180-220℃, the middle temperature being 120-160℃, and the outlet temperature being 80-100℃, resulting in a particle size of 50-200μm for the small-diameter spherical abrasive matrix.

[0009] A further improvement to the above scheme is that, in step S1, the small-diameter spherical abrasive matrix is ​​subjected to surface activation treatment during the spray granulation process to increase the surface energy of the matrix and improve the interfacial bonding between the subsequent coating slurry and the matrix; the surface activation treatment is plasma activation treatment, and the surface energy of the small-diameter spherical abrasive matrix after activation is 40-60 mN / m.

[0010] A further improvement to the above scheme is that, in step S2, the drum rotation speed of the drum agglomeration device is 10-30 rpm, the drum inclination angle is 5-15°, the filling rate is 20%-40%, the spraying volume of the coating slurry is 0.5-2.0 L / h, and the particle size of the sprayed droplets is 10-50 μm; the drum agglomeration device is equipped with a spiral guide plate and a grading baffle to guide the particles to tumble, collide, and grow in the drum in a graded manner.

[0011] A further improvement to the above scheme is that, in step S3, the infrared dynamic drying adopts a combination of mid-infrared and far-infrared radiation, with the mid-infrared wavelength range being 2.5-5μm, the far-infrared wavelength range being 5-15μm, the infrared power density being 0.5-2.0kW / m², and the single radiation time being 30-120s.

[0012] A further improvement to the above scheme is that the roller agglomeration device is equipped with an infrared reflector to improve the utilization rate of infrared radiation.

[0013] A further improvement to the above scheme is that, in step S4, the post-processing is a low-temperature curing process, with a curing temperature of 80-120℃ and a curing time of 1-3h, and the target particle size range obtained after sieving is 200-800μm.

[0014] A further improvement to the above scheme is that the abrasive powder is one or more of diamond, silicon carbide, alumina, cerium oxide, and zirconium oxide.

[0015] A further improvement to the above scheme is to set up an online monitoring unit during the preparation process to detect at least one parameter among particle size, temperature and humidity, and to adjust at least one of the spray granulation parameters, coating slurry injection parameters and infrared drying parameters based on the detection results.

[0016] A large-particle spherical abrasive is prepared by a method comprising a spherical matrix and a shell layer covering the outer periphery of the spherical matrix. The shell layer is formed by layer-by-layer coating growth and solidification of a coating slurry containing abrasive powder, so that the large-particle spherical abrasive has a spherical stacked structure.

[0017] A further improvement to the above scheme is that the particle size of the spherical matrix is ​​50-200μm, and the particle size of the large-particle spherical abrasive is 200-800μm.

[0018] A further improvement to the above scheme is that the stacked shell is a multi-layered covering structure formed around the spherical substrate, and the multi-layered covering structure includes 3-8 layers stacked sequentially.

[0019] A further improvement to the above scheme is that the large-particle spherical abrasive has a gradient distribution with increasing binder content from the inside out.

[0020] A further improvement to the above scheme is that the sphericity of the large-particle spherical abrasive is not less than 0.95, and the particle size distribution satisfies D90 / D10≤1.5.

[0021] The beneficial effects of this invention are: Compared with existing abrasive preparation methods, this invention first obtains a small-diameter spherical abrasive matrix through spray granulation, and then coats the outer periphery of the matrix with a slurry containing abrasive powder layer by layer during the roller agglomeration process. Combined with synchronous infrared dynamic drying, the particles do not form a homogeneous structure through one-step spherical formation, but rather form a stacked shell structure with the spherical matrix as the core and the outer layers growing gradually. This is beneficial to improving the integrity of the particle structure and the stability of the interlayer bonding.

[0022] This invention achieves a continuous state of tumbling, collision, and uniform heating of particles during the agglomeration process through the coordinated control of spray granulation, roller agglomeration, and simultaneous drying. This reduces local adhesion and morphological instability, thereby obtaining large-particle spherical abrasive with high sphericity and concentrated particle size distribution.

[0023] This invention implements synchronous infrared dynamic drying during the drum agglomeration process, which allows the coated slurry to remove moisture and solidify in a timely manner after each layer is coated. This reduces the problem of surface hardening and excessive internal moisture in traditional hot air drying, thereby improving the interlayer bonding quality and increasing the overall strength and stability of the particles.

[0024] This invention implements the preparation of spray granulation matrix, roller agglomeration coating and infrared dynamic drying in stages, and can adjust parameters such as atomization pressure, roller speed, spray volume and infrared power density respectively. Therefore, it is easier to optimize the process for different abrasive systems and target particle size ranges and expand the scope of application of the process.

[0025] This invention couples drum agglomeration with infrared dynamic drying, achieving moisture removal and structural solidification while particles grow, reducing the need for separate static drying or repeated drying steps, thereby improving production efficiency and reducing overall energy consumption.

[0026] This invention is applicable not only to diamond abrasives, but also to various abrasive systems such as silicon carbide, alumina, cerium oxide, and zirconium oxide, and has good versatility and industrial promotion value.

[0027] In a preferred embodiment, by setting up online monitoring and parameter feedback adjustment, parameters such as particle size, temperature and humidity can be dynamically monitored and corrected, thereby improving batch-to-batch preparation stability and product consistency. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the spray granulation device of the present invention; Figure 2 This is a schematic diagram of the drying tower of the present invention; Figure 3 This is a schematic diagram of the structure of the drum agglomeration device of the present invention; Figure 4 This is a schematic diagram of the process structure for preparing the large-particle spherical abrasive of the present invention; Figure 5 This is a schematic flowchart of the preparation method of the large-particle spherical abrasive of the present invention.

[0029] Explanation of reference numerals in the attached figures: 1. Spray granulation device, 2. Drying tower, 3. Roller agglomeration device, 31. Spiral guide plate, 32. Grading baffle. Detailed Implementation

[0030] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0031] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0033] like Figures 1-5 As shown, the present invention provides a method for preparing large-particle spherical abrasive, which adopts a "three-stage synergistic process" and includes: spray granulation to prepare a small-diameter spherical abrasive matrix; roller agglomeration to achieve layer-by-layer coating growth; infrared dynamic drying and post-treatment sieving.

[0034] The first stage is mainly used to form a spherical matrix with a smaller particle size and more regular morphology; the second stage is mainly used to coat the spherical matrix with a slurry containing abrasive powder layer by layer, so that the particle size gradually increases; the third stage is mainly used to simultaneously remove moisture and solidify the structure during the agglomeration process, and then obtain large-particle spherical abrasives with a target particle size range after low-temperature solidification and sieving.

[0035] The abrasive powder of this invention can be one or more of diamond, silicon carbide, alumina, cerium oxide, and zirconium oxide, and the specific selection can be made according to the application. The binder can be polyvinyl alcohol, polyacrylate, cellulose derivatives, or other organic binders that can provide sphericity and coating adhesion. The dispersant can be polycarboxylate dispersants, lignin sulfonate dispersants, or other dispersants suitable for inhibiting particle agglomeration. The solvent is preferably water, but other liquid media can be selected according to the material system.

[0036] First, abrasive powder, binder, dispersant, and solvent are mixed to prepare a slurry for spray granulation. The solid content of the slurry is preferably 20%-50%. When the solid content is too low, the abrasive content per unit volume of slurry is low, which is not conducive to forming a spherical matrix with good strength; when the solid content is too high, the viscosity of the slurry increases, which is not conducive to atomization and stable spraying.

[0037] The prepared slurry enters the spray granulation device 1. Spray granulation preferably employs a two-fluid atomization method, where fine droplets are formed through the synergistic effect of airflow and slurry. The atomization pressure is preferably 0.3-0.8 MPa, and the atomization angle is preferably 60-120°. By adjusting the atomization pressure and atomization angle, the initial droplet size and distribution can be controlled, thereby affecting the final spherical matrix particle size.

[0038] During the spray granulation process, a temperature gradient is set along the material flow direction in the drying tower 2, preferably: 180-220℃ in the inlet zone, 120-160℃ in the middle zone, and 80-100℃ in the outlet zone. Through segmented temperature control, the droplets can be rapidly shaped in the initial stage, stably dehydrated in the middle stage, and slowly dried in the later stage, avoiding problems such as cracking, collapse, or excessive residual moisture inside due to uneven drying rate.

[0039] The preferred particle size of the small-diameter spherical abrasive matrix obtained after spray granulation is 50-200 μm. This particle size range facilitates the subsequent gradual deposition and growth of the outer layer as core particles during drum agglomeration.

[0040] In a preferred embodiment, the spherical matrix can also undergo surface activation treatment during spray granulation, for example, using plasma activation treatment. After activation, the surface energy of the spherical matrix can be increased to 40-60 mN / m, thereby helping to enhance the wettability and adhesion of the subsequent coating slurry to the matrix surface and improve the interlayer bonding quality.

[0041] The aforementioned small-diameter spherical abrasive matrix is ​​placed into the roller agglomeration device 3, and simultaneously a coating slurry containing abrasive powder is sprayed into the roller agglomeration device 3. The coating slurry may contain abrasive powder, binder, dispersant, and solvent. Its composition may be the same as that of the spray granulation slurry, or it may be adjusted according to the requirements of the outer coating, for example, by increasing the binder content to enhance the layering stability of the outer coating.

[0042] When the drum agglomeration device 3 is working, the spherical matrix continuously tumbles, collides, and moves inside the drum, and the sprayed coating slurry adheres to the surface of the spherical matrix in the form of droplets. As the particles continue to tumble, the droplets spread on the surface and adsorb the abrasive particles, causing a coating layer to gradually form on the outer periphery of the particles. As spraying and tumbling continue, the coating layer repeatedly grows, thus forming a large-particle spherical accumulation structure that gradually thickens from the core to the outer layer.

[0043] The preferred process parameters for roller agglomeration are as follows: roller speed 10-30 rpm, roller inclination angle 5-15°, filling rate 20%-40%, coating slurry spraying volume 0.5-2.0 L / h, and droplet size 10-50 μm.

[0044] Among them: the drum rotation speed affects the tumbling frequency and collision state of the particles; the drum tilt angle affects the axial movement speed of the particles in the drum; the filling rate affects the contact probability between particles and the uniformity of coating; the spray volume and droplet size affect the growth rate of the coating layer and the uniformity of the layer surface.

[0045] To further optimize the agglomeration and coating effects, the present invention preferably includes a spiral guide plate 31 and a grading baffle 32 inside the drum. The spiral guide plate 31 guides the particles to move along the drum axis and enhances the regularity of particle tumbling; the grading baffle 32 can create different residence and tumbling conditions for particles of different sizes, which helps to reduce the size dispersion of particles during the agglomeration process and improve the uniformity of coating.

[0046] After this stage of treatment, the particles gradually grow from the original spherical matrix into large spherical particles with obvious core-shell stacking characteristics. Preferably, the formed coating layer can be a 3-8 layer stacked structure, and exhibit a gradient distribution of binder content increasing from the inside to the outside to improve the transition connection between different layers.

[0047] During the drum agglomeration process, this invention does not wait until the particles have completed agglomeration before drying, but instead performs infrared dynamic drying simultaneously during the agglomeration process. This method allows the newly formed coating layer to lose some moisture and solidify in a shorter time, preventing the particles from severely sticking together, collapsing, or becoming morphologically unstable due to excessive surface moisture.

[0048] The infrared dynamic drying process preferably employs a combination of mid-infrared and far-infrared radiation. The preferred mid-infrared wavelength range is 2.5-5 μm, and the preferred far-infrared wavelength range is 5-15 μm. Mid-infrared radiation facilitates faster heating of moisture and organic components in the coating layer, while far-infrared radiation promotes more uniform heat transfer. This combination achieves a balance between drying speed and drying uniformity.

[0049] The preferred process parameters for infrared dynamic drying are: infrared power density of 0.5-2.0 kW / m², and single irradiation time of 30-120 s. By adjusting the infrared power density and irradiation time, synchronous matching can be achieved according to particle size, coating thickness, and slurry moisture content.

[0050] In a preferred embodiment, an infrared reflector is provided in the infrared radiation zone to improve the utilization rate of infrared energy, reduce heat loss, and allow the particles to receive more uniform radiation during tumbling inside the drum.

[0051] Compared with traditional hot air drying methods, this invention implements infrared dynamic drying simultaneously during the drum agglomeration stage, which can reduce the problems of premature surface hardening and excessive internal residual moisture, thereby facilitating the production of spherical abrasive particles with denser interlayer bonding and higher overall strength.

[0052] After drum agglomeration and infrared dynamic drying, the resulting particles enter the post-processing stage. Low-temperature curing is preferred for post-processing to further stabilize the particle structure and improve interlayer bonding strength. The preferred low-temperature curing temperature is 80-120℃, and the preferred curing time is 1-3 hours.

[0053] After low-temperature curing, large-particle spherical abrasive particles within the target particle size range are screened using vibratory sieving or other grading methods. The desired target particle size range is preferably 200-800 μm. This particle size range not only meets the particle size requirements for precision grinding and polishing applications but also demonstrates the improvement in particle size compared to ordinary micro-fine spherical abrasives.

[0054] In a preferred embodiment, the resulting large-particle spherical abrasive has the following characteristics: It uses a small-diameter spherical abrasive matrix as the core; the outer periphery has a layered coating layer formed by progressive growth; the number of coating layers is preferably 3-8; the overall sphericity of the particles is high; and the particle size distribution is relatively concentrated.

[0055] Under further optimization, the sphericity of the obtained product can be no less than 0.95, and the particle size distribution satisfies D90 / D10≤1.5.

[0056] To improve process stability, the present invention can also set up an online monitoring unit during the preparation process to detect at least one parameter among particle size, temperature and humidity.

[0057] For example, during the spray granulation stage, the atomization state and outlet particle size can be detected to adjust the atomization pressure, slurry supply, or drying tower 2 temperature; during the drum agglomeration stage, the particle agglomeration state, material temperature, and humidity inside the drum can be detected to adjust the drum speed, spray volume, and infrared power density; and during the post-treatment stage, the particle moisture content and particle size distribution can be detected to optimize the low-temperature curing time and sieving range.

[0058] Through the above-mentioned online monitoring and feedback adjustment, the parameters of each process stage can be matched with the actual particle growth state, thereby improving the repeatability of the preparation process and the consistency of the product.

[0059] Example 1: Preparation of large diamond particle spherical abrasive Raw material preparation: Diamond micro powder with a particle size of 5μm was used as the abrasive powder. Polyvinyl alcohol 1788 binder 3%, dispersant 0.5%, and the remainder deionized water were added by mass percentage to prepare a slurry with a solid content of 35%.

[0060] Spray granulation: Spray granulation was performed using a two-fluid atomization method with an atomization pressure of 0.5 MPa. The temperature gradient of drying tower 2 was set as follows: 200℃ in the inlet zone, 140℃ in the middle zone, and 90℃ in the outlet zone, to obtain a small-diameter spherical abrasive matrix with a particle size of approximately 150 μm.

[0061] The resulting matrix is ​​subjected to surface activation treatment during spray granulation to improve its surface activity.

[0062] Roller aggregation: The spherical substrate was placed into the roller agglomeration device 3, with the roller speed set to 20 rpm, the roller inclination angle set to 10°, and the filling rate set to 30%. A coating slurry containing diamond powder was sprayed into the roller at a spray rate of 1.0 L / h, so that the spherical substrate would grow layer by layer during the tumbling process.

[0063] Spherical abrasives were prepared using an existing one-step spray drying process. Specifically, diamond micro powder, binder, dispersant and deionized water were mixed to form a slurry, and then spherical particles were obtained directly by spray drying. No roller agglomeration coating or infrared dynamic drying treatment was performed. The remaining raw material system was basically the same as in Example 1.

[0064] The product obtained in Example 1 and the product obtained in Comparative Example 1 were tested, and the results are shown in Table 1.

[0065] Table 1. Performance Comparison of Products in Example 1 and Comparative Example 1 of the Present Invention

[0066] As can be seen from Table 1, the large-particle spherical abrasive obtained by using the spray granulation matrix, roller agglomeration layer-by-layer coating and infrared dynamic drying synergistic process of the present invention is superior to the product obtained by the traditional one-step spray drying method in terms of sphericity, particle size uniformity, compressive strength, flowability and grinding ratio. This indicates that the present invention is conducive to forming spherical abrasive with more stable structure, higher strength and better processing performance.

[0067] Infrared dynamic drying: Infrared dynamic drying is carried out simultaneously during the drum agglomeration process, using a combination of mid-infrared and far-infrared radiation. The infrared power density is set to 1.2kW / m², the single radiation time is set to 60s, and an infrared reflector is set in the radiation area.

[0068] Post-processing and screening: The agglomerated and dried particles were subjected to low-temperature solidification treatment at 100℃ for 2 hours, and then obtained as large diamond spherical abrasive particles with a particle size of 400-600μm by vibration sieving.

[0069] The resulting product has good sphericity retention and interlayer bonding quality, and is suitable for precision grinding and polishing.

[0070] Example 2: Preparation of silicon carbide large-particle spherical packed abrasive The abrasive powder was replaced with silicon carbide micro powder, and the remaining process steps were basically the same as in Example 1. Based on the surface characteristics and slurry rheological properties of silicon carbide material, the parameters of spray granulation and roller agglomeration were adaptively adjusted, and large-particle silicon carbide abrasive with a spherical packing structure within the target particle size range could be obtained in the end.

[0071] The large-particle spherical abrasive prepared by this invention can be used for precision grinding and polishing of materials such as semiconductor wafers, optical components, precision molds, metals, ceramics and glass, and can also be further used in the preparation of high-performance grinding wheels, grinding pastes and other abrasive products.

[0072] Because this abrasive has high sphericity, good fluidity, and stable structural strength, it is more conducive to obtaining stable surface quality and high processing efficiency during transportation, dispersion, and processing.

[0073] To illustrate the effect of simultaneous infrared dynamic drying during the drum agglomeration process, a comparative experiment was conducted with and without infrared dynamic drying under the same raw material system and drum agglomeration parameters as in Example 1. The results are shown in Table 2.

[0074] Table 2. Effects of Infrared Dynamic Drying on Product Performance

[0075] As shown in Table 2, when infrared dynamic drying is used simultaneously during the drum agglomeration process, the particles exhibit higher sphericity, greater compressive strength, lower porosity, and better flowability. This is because infrared dynamic drying can promptly remove moisture from the coating layer during the layer-by-layer growth of the particles, mitigating the problem of uneven drying between the surface and inner layers, thus facilitating the formation of a denser interlayer bond structure.

[0076] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A method for preparing large-particle spherical abrasive, characterized in that, Includes the following steps: S1. Abrasive powder, binder, dispersant and solvent are mixed to form a slurry, and small-diameter spherical abrasive matrix is ​​prepared by spray granulation process; S2. The small-diameter spherical abrasive matrix is ​​put into the roller agglomeration device, and a coating slurry containing abrasive powder is sprayed into the roller agglomeration device, so that the small-diameter spherical abrasive matrix grows layer by layer during the rolling agglomeration process to form large spherical aggregated particles. S3. During the rolling agglomeration process, the large spherical stacked particles are simultaneously subjected to infrared dynamic drying, so that the coating layer gradually solidifies and forms a stable stacked structure. S4. The particles after drum agglomeration and infrared dynamic drying are post-processed and sieved to obtain large-particle spherical abrasive within the target particle size range.

2. The method for preparing large-particle spherical abrasive according to claim 1, characterized in that, In step S1, the solid content of the slurry is 20%-50%, and the spray granulation process adopts a two-fluid atomization method with an atomization pressure of 0.3-0.8MPa and an atomization angle of 60-120°. The drying tower for spray granulation is equipped with a temperature gradient along the material flow direction. The inlet temperature is 180-220℃, the middle temperature is 120-160℃, and the outlet temperature is 80-100℃. The resulting small-diameter spherical abrasive matrix has a particle size of 50-200μm.

3. The method for preparing large-particle spherical abrasive according to claim 1, characterized in that, In step S1, the small-diameter spherical abrasive matrix is ​​subjected to surface activation treatment during the spray granulation process to improve the surface energy of the matrix and improve the interfacial bonding between the subsequent coating slurry and the matrix. The surface activation treatment is plasma activation treatment, and the surface energy of the small-particle-size spherical abrasive matrix after activation is 40-60 mN / m.

4. The method for preparing large-particle spherical abrasive according to claim 1, characterized in that, In step S2, the drum rotation speed of the drum agglomeration device is 10-30 rpm, the drum inclination angle is 5-15°, the filling rate is 20%-40%, the spraying volume of the coating slurry is 0.5-2.0 L / h, and the droplet size is 10-50 μm. The drum agglomeration device is equipped with a spiral guide plate and a grading baffle to guide the particles to tumble, collide, and grow in the drum.

5. The method for preparing large-particle spherical abrasive according to claim 1, characterized in that, In step S3, the infrared dynamic drying uses a combination of mid-infrared and far-infrared radiation, with the mid-infrared wavelength range being 2.5-5μm, the far-infrared wavelength range being 5-15μm, the infrared power density being 0.5-2.0kW / m², and the single radiation time being 30-120s; the drum agglomeration device is equipped with an infrared reflector to improve the utilization rate of infrared radiation. In step S4, the post-processing is a low-temperature curing process, with a curing temperature of 80-120℃ and a curing time of 1-3h. The target particle size range obtained after sieving is 200-800μm. The abrasive powder is one or more of diamond, silicon carbide, alumina, cerium oxide, and zirconium oxide.

6. The method for preparing large-particle spherical abrasive according to claim 1, characterized in that, An online monitoring unit is set up during the preparation process to detect at least one of the parameters of particle size, temperature and humidity, and to adjust at least one of the parameters of spray granulation, coating slurry injection and infrared drying based on the detection results.

7. A large-particle spherical abrasive, characterized in that, The large-particle spherical abrasive is prepared by any one of claims 1 to 6. The large-particle spherical abrasive includes a spherical matrix and a stacked shell layer covering the outer periphery of the spherical matrix. The stacked shell layer is formed by layer-by-layer coating growth and solidification of a coating slurry containing abrasive powder, so that the large-particle spherical abrasive has a spherical stacked structure.

8. The large-particle spherical abrasive according to claim 7, characterized in that, The particle size of the spherical matrix is ​​50-200 μm, and the particle size of the large-particle spherical abrasive is 200-800 μm.

9. The large-particle spherical abrasive according to claim 7, characterized in that, The stacked shell is a multi-layered covering structure formed around the spherical matrix, and the multi-layered covering structure includes 3-8 layers stacked sequentially.

10. The large-particle spherical abrasive according to claim 7, characterized in that, The large-particle spherical abrasive has a gradient distribution with increasing binder content from the inside out; The sphericity of the large-particle spherical abrasive is not less than 0.95, and the particle size distribution satisfies D90 / D10≤1.5.

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