Process for the preparation of a solid-sphere-shaped alumina granulated powder

Abstract

The application discloses a preparation method of solid spherical alumina granulation powder, wherein specific anion surface active dispersants are added first to disperse and mix alumina powder and sintering aids, specific cation surface active dispersants are added later to neutralize the surface charge of the anion surface active dispersants, alumina slurry is obtained, and finally, the solid spherical alumina granulation powder is obtained through spray granulation. Through the preparation method, the uniformity of the mixture of the alumina powder and the sintering aids can be ensured, and the alumina slurry can be granulated into solid spheres.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials technology, specifically to a method for preparing solid spherical alumina granulated powder. Background Technology

[0002] Alumina ceramics possess characteristics such as high strength, good corrosion resistance, and excellent insulation, and are widely used in new energy vehicles, LEDs, semiconductors, and other fields. Dry pressing is one of the main processes for manufacturing alumina ceramic parts, offering advantages such as high production efficiency, high automation, and low production costs.

[0003] Because alumina powder is a brittle raw material with low bulk density and poor flowability, it cannot be directly used in dry pressing processes. Therefore, before dry pressing, alumina powder needs to be prepared into a slurry, and then dried using a spray granulation method to form alumina granulated powder with good flowability. Alumina granulated powder generally has three morphologies: solid spheres, apple-shaped, and hollow spheres. Among these, solid spherical alumina granulated powder has the best flowability and the highest bulk density. However, it is difficult to manufacture completely solid spherical alumina granulated powder in actual production. Chinese invention patent CN104150883B discloses a method for preparing alumina granulated powder, proposing the use of a combination of centrifugation and pressure to manufacture solid granulated powder. However, this method suffers from problems such as complex manufacturing equipment structure, difficult production control, and a certain proportion of hollow spheres in the product. Therefore, finding a simple and controllable method for manufacturing completely solid spherical alumina granulated powder is an urgent problem that the entire industry needs to solve. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing solid spherical alumina granulated powder. By adjusting the dispersibility of the alumina slurry, the alumina granulated powder can be made into completely solid spherical powder. This method has simple requirements for manufacturing equipment and low control difficulty.

[0005] To achieve the above objectives, the solution of the present invention is:

[0006] A method for preparing solid spherical alumina granulated powder includes the following steps:

[0007] Step 1: According to the formula, first put 50wt% to 60wt% alumina powder, 3wt% to 6wt% sintering aid, 0.2wt% to 0.6wt% anionic surfactant dispersant and 35wt% to 45wt% deionized water into a ball mill for ball milling and dispersion to obtain alumina slurry A;

[0008] Step 2: According to the mixing ratio, add the binder and plasticizer to alumina slurry A, and then ball mill and mix to obtain alumina slurry B;

[0009] The amount of the binder added is 1.0% to 3.0% of the mass of alumina powder, and the amount of the plasticizer added is 0.5% to 3.0% of the mass of alumina powder.

[0010] Step 3: According to the ratio, add the cationic surfactant dispersant to the alumina slurry B, and ball mill and disperse it again to obtain alumina slurry C. The amount of cationic surfactant dispersant added is 0.05% to 0.15% of the mass of alumina powder.

[0011] Step 4: Finally, the alumina slurry C is spray-granulated. The spray-granulation conditions are: inlet air temperature: 250~280℃, outlet air temperature: 100~110℃, tower pressure: -10~50Pa, to obtain the solid spherical alumina granulated powder.

[0012] In step 1, the molecular structure of the anionic surfactant dispersant is shown in Formula I:

[0013]

[0014] In Formula I, R1 and R2 are H, COOH, and COO, respectively. - Na + COO - K + COO - NH + 4. COO - N + H(CH3)2CH2CH2OH, COO - N + One or more of H(CH2CH3)3, R3 is one of butyl, isobutyl, isooctyl and isobornyl ester, R4 is one of H and methyl; a = 0.1~0.4, b = 0.16~0.67, c = 0.23~0.44, n = 3~14, where the values ​​of a, b and c are the molar ratios of the corresponding monomers;

[0015] In step 3, the molecular structure of the cationic surfactant dispersant is shown in Figure II:

[0016]

[0017] In Formula II, R1, R2 and R5 are one of H and methyl, respectively; R3 is one of butyl, isobutyl, isooctyl and isobornyl; and R4 is one of H and methyl.

[0018] R6 is One of CH3COOCH2CH(OH)CH2-;

[0019] a = 0.1–0.4, b = 0.16–0.67, c = 0.23–0.44, n = 3–14, where a, b, and c are the molar ratios of the corresponding monomers.

[0020] In step 1, the alumina powder has a particle size of 2.0 to 3.0 μm, and the sintering aid includes 15 wt% to 45 wt% SiO2, 15 wt% to 23 wt% CaCO3, and 33 wt% to 70 wt% talc.

[0021] In step 1, the ball mill rotates at a speed of 20–35 rpm, and the ball milling time is 12–24 h.

[0022] In step 2, the adhesive is one of polyvinyl alcohol and water-based acrylic resin, and the plasticizer is one or both of polyethylene glycol and glycerin.

[0023] In step 2, the ball mill rotates at a speed of 20-35 rpm and the milling time is 2-6 hours; in step 3, the ball mill rotates at a speed of 20-35 rpm and the milling time is 1-5 hours.

[0024] In step 1, the preparation method of the anionic surfactant dispersant is as follows: First, add 5-30 parts of maleic anhydride or acrylic acid monomer, 23-64 parts of polyethylene glycol monoether acrylate, 20-60 parts of (meth)acrylate monomer, 0.5-5 parts of initiator, and 60-140 parts of solvent to a container in sequence, and stir evenly at room temperature to obtain a homogeneous mixed solution; then add 30-60 parts of the mixed solution to a four-necked flask, and continuously purge with nitrogen gas, raise the temperature to 75-95°C, and keep it at this temperature for 20-90 minutes. Then, add the remaining mixed solution dropwise over 0.5-4 hours, and keep it at this temperature for 1-3 hours. Then, add 30-100 parts of deionized water to cool the temperature to below 40°C, and add 5-40 parts of neutralizing reagent to carry out a neutralization reaction. After reacting for 0.5-1 hour, remove the solvent by vacuum distillation to obtain the anionic surfactant dispersant.

[0025] The (meth)acrylate monomer is one of butyl (meth)acrylate, isobutyl (meth)acrylate, isooctyl (meth)acrylate, and isobornyl (meth)acrylate; the initiator is one of azobisisobutyronitrile and ammonium persulfate; the solvent is one or more of ethyl acetate, isopropanol, water, toluene, propylene glycol methyl ether, and butyl acetate; and the neutralizing agent is one of sodium hydroxide, potassium hydroxide, N,N-dimethylethanolamine, triethylamine, ammonia, and ammonium hydroxide.

[0026] In step 3, the preparation method of the cationic surfactant dispersant is as follows: First, add 5-40 parts of cationic monomer, 23-64 parts of polyethylene glycol monoether acrylate, 20-60 parts of (meth)acrylate monomer, 0.5-5 parts of initiator, and 60-140 parts of solvent to a container, and stir evenly at room temperature to obtain a homogeneous mixed solution; then add 30-60 parts of the mixed solution to a four-necked flask, and continuously purge with nitrogen gas, raise the temperature to 75-95°C, and keep it at this temperature for 20-90 min; then add the remaining mixed solution dropwise over 0.5-4 h, and keep it at this temperature for 1-3 h; then cool the temperature to below 60°C, add 5-40 parts of chloride, and continue to keep it at this temperature for 0.5-2 h; then add 20-50 parts of deionized water and cool the temperature to below 40°C; finally, add 5-40 parts of fatty acid, react for 0.5-1 h, and then remove the solvent by vacuum distillation to obtain the cationic surfactant dispersant.

[0027] The cationic monomer is one of dimethylaminoethyl methacrylate, N,N-dimethylacrylamide, and acrylamide; the methacrylate monomer is one of butyl methacrylate, isobutyl methacrylate, isooctyl methacrylate, and isobornyl methacrylate; the initiator is one of azobisisobutyronitrile and ammonium persulfate; the solvent is one or more of ethyl acetate, isopropanol, water, toluene, propylene glycol methyl ether, and butyl acetate; the chloride is one of methyl chloroacetate, epichlorohydrin, and chloroacetic acid; and the fatty acid is one of acetic acid, lauric acid, and stearic acid.

[0028] By adopting the above technical solution, the present invention provides a method for preparing solid spherical alumina granulated powder. First, a specific anionic surfactant dispersant is added to disperse and mix alumina powder and sintering aid. Then, a specific cationic surfactant dispersant is added to neutralize the surface charge of the anionic surfactant dispersant, resulting in an alumina slurry. Finally, spray granulation is performed to obtain solid spherical alumina granulated powder. This preparation method ensures the uniformity of the mixture of alumina powder and sintering aid, and improves the yield stress and thixotropy of the alumina slurry, achieving a solid spherical shape after granulation. Overall, the present invention achieves complete solid sphericalization of alumina granulated powder by adjusting the dispersibility of the alumina slurry using two dispersants with opposite properties. It requires simple manufacturing equipment and has low control difficulty. Attached Figure Description

[0029] Figure 1 This is a SEM scan of the solid spherical alumina granulated powder prepared in Example 7;

[0030] Figure 2 The image shows a SEM scan of the ordinary spherical alumina granulated powder prepared in Comparative Example 1. Detailed Implementation

[0031] To further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

[0032] 1. Preparation of solid spherical alumina granules

[0033] (1) Preparation of anionic surfactant dispersants

[0034] Example 1

[0035] First, 25 parts of maleic anhydride, 35 parts of polyethylene glycol monoether acrylate, 30 parts of (meth)acrylate isobornyl ester, 2 parts of azobisisobutyronitrile, and 100 parts of propylene glycol methyl ether were added sequentially to a three-necked flask and stirred at room temperature to obtain a homogeneous mixed solution. Then, 30 parts of the mixed solution were added to a four-necked flask, and nitrogen gas was continuously introduced. The temperature was raised to 80°C within 30 minutes and held for 30 minutes. The remaining mixed solution was then added dropwise over 3 hours and held for 3 hours. Subsequently, 50 parts of deionized water were added to cool the temperature to below 40°C, and 30 parts of ammonium hydroxide were added for neutralization. After reacting for 30 minutes, the solvent was removed by vacuum distillation to obtain the anionic surfactant dispersant.

[0036] The molecular structure of this anionic surfactant dispersant is shown in Formula III:

[0037]

[0038] Where a = 0.22–0.30, b = 0.40–0.46, c = 0.35–0.41, and n = 7–9.

[0039] Example 2

[0040] First, 20 parts of acrylic acid, 40 parts of polyethylene glycol monoether acrylate, 30 parts of (meth)acrylate isobornyl ester, 1.5 parts of azobisisobutyronitrile, and 90 parts of ethyl acetate were added sequentially to a three-necked flask and stirred at room temperature to obtain a homogeneous mixed solution. Then, 30 parts of the mixed solution were added to a four-necked flask, and nitrogen gas was continuously introduced. The temperature was raised to 80°C within 30 minutes and held for 30 minutes. Subsequently, the remaining mixed solution was added dropwise over 2.5 hours and held at the temperature for 1 hour. Then, 30 parts of deionized water were added to dissolve the solution and the temperature was lowered to below 40°C. 20 parts of N,N-dimethylethanolamine were added for neutralization, and the solvent was removed by vacuum distillation to obtain the anionic surfactant dispersant.

[0041] The molecular structure of this anionic surfactant dispersant is shown in Formula IV:

[0042]

[0043] Where a = 0.20–0.28, b = 0.50–0.56, c = 0.35–0.41, and n = 8.

[0044] Example 3

[0045] First, 30 parts of acrylic acid, 20 parts of polyethylene glycol monoether acrylate, 40 parts of (meth)acrylate butyl acrylate, 2.5 parts of azobisisobutyronitrile, and 100 parts of ethyl acetate were added sequentially to a three-necked flask and stirred at room temperature to obtain a homogeneous mixed solution. Then, 30 parts of the mixed solution were added to a four-necked flask, and nitrogen gas was continuously introduced. The temperature was raised to 75°C within 30 minutes and held for 30 minutes. The remaining mixed solution was then added dropwise over 3 hours and held at the same temperature for 3 hours. Subsequently, 50 parts of deionized water were added to dissolve the solution and the temperature was lowered to below 40°C. 20 parts of N,N-dimethylethanolamine were added for neutralization, and the solvent was removed by vacuum distillation to obtain the anionic surfactant dispersant.

[0046] The molecular structure of this anionic surfactant dispersant is shown in Formula V:

[0047]

[0048] Where a = 0.35–0.40, b = 0.50–0.56, c = 0.35–0.41, and n = 8.

[0049] (2) Preparation of cationic surfactant dispersants

[0050] Example 4

[0051] First, add 30 parts of N,N-dimethylacrylamide, 50 parts of polyethylene glycol monoether acrylate, 20 parts of (meth)acrylate isobornyl ester, 2 parts of azobisisobutyronitrile, and 100 parts of propylene glycol methyl ether to a three-necked flask and stir until homogeneous at room temperature to obtain a uniform mixed solution. Then, add 30 parts of the mixed solution to a four-necked flask and continuously purge with nitrogen gas. Raise the temperature to 80°C within 30 minutes and hold for 30 minutes. Then, add the remaining mixed solution dropwise over 3 hours and hold for 3 hours to remove the solvent. Then, cool down to below 60°C and add 30 parts of epichlorohydrin. Continue to hold for 1 hour, then add 50 parts of deionized water and cool down to below 40°C. Then, add 30 parts of acetic acid and react for half an hour. Remove the solvent by vacuum distillation to obtain the cationic surfactant dispersant.

[0052] The molecular structure of this cationic surfactant dispersant is shown in Figure VI:

[0053]

[0054] Where a = 0.27–0.33, b = 0.47–0.53, c = 0.36–0.40, and n = 7–9.

[0055] Example 5

[0056] First, 30 parts of acrylamide, 40 parts of polyethylene glycol monoether acrylate, 30 parts of isobornyl methacrylate, 2 parts of azobisisobutyronitrile, and 100 parts of propylene glycol methyl ether were added to a three-necked flask and stirred at room temperature to obtain a homogeneous mixed solution. Then, 30 parts of the mixed solution were added to a four-necked flask, and nitrogen gas was continuously introduced. The temperature was raised to 90°C within 30 minutes, and the remaining mixed solution was added dropwise over 3 hours. The temperature was maintained for 2 hours, then lowered to below 60°C, and 32 parts of epichlorohydrin were added. The temperature was maintained for another 1 hour. Then, 40 parts of deionized water were added, and the temperature was lowered to below 40°C. Then, 32 parts of acetic acid were added, and the reaction was carried out for half an hour. The solvent was removed by vacuum distillation to obtain the cationic surfactant dispersant.

[0057] The molecular structure of this cationic surfactant dispersant is shown in VII:

[0058]

[0059]

[0060] Where a = 0.27–0.33, b = 0.47–0.53, c = 0.36–0.40, and n = 7–9.

[0061] (3) Preparation of solid spherical alumina granules

[0062] Example 6

[0063] A method for preparing solid spherical alumina granulated powder includes the following steps:

[0064] Step 1: According to the ratio, first put 60wt% alumina powder, 4.5wt% sintering aid, 0.5wt% anionic surfactant dispersant prepared in Example 1 and 35wt% deionized water into a horizontal ball mill for ball milling and dispersion. The ball mill speed is 30rpm and the ball milling is carried out for 18h to obtain alumina slurry A.

[0065] Step 2: According to the ratio, add polyvinyl alcohol and polyethylene glycol to alumina slurry A, and ball mill them together at a speed of 30 rpm for 6 hours to obtain alumina slurry B.

[0066] The amount of polyvinyl alcohol added is 1.0% of the mass of alumina powder, and the amount of polyethylene glycol added is 1.0% of the mass of alumina powder.

[0067] Step 3: According to the ratio, add the cationic surfactant dispersant prepared in Example 4 to alumina slurry B, and disperse it by ball milling again. The ball milling speed is 30 rpm and the ball milling time is 3 hours to obtain alumina slurry C. The amount of cationic surfactant dispersant added is 0.15% of the mass of alumina powder.

[0068] Step 4: Finally, a centrifugal spray granulation tower is used to spray granulate the alumina slurry C. The spray granulation conditions are: inlet air temperature: 250℃, outlet air temperature: 100℃, tower pressure: 30Pa, to obtain the solid spherical alumina granulated powder.

[0069] In step 1, the alumina powder has a particle size of 2.0–3.0 μm, and the sintering aids include 30 wt% SiO2, 20 wt% CaCO3, and 50 wt% talc.

[0070] Example 7

[0071] A method for preparing solid spherical alumina granulated powder includes the following steps:

[0072] Step 1: According to the ratio, first put 55wt% alumina powder, 4.4wt% sintering aid, 0.6wt% anionic surfactant dispersant prepared in Example 2 and 40wt% deionized water into a horizontal ball mill for ball milling and dispersion. The ball mill speed is 20rpm and the ball milling is carried out for 12h to obtain alumina slurry A.

[0073] Step 2: According to the ratio, add water-based acrylic resin and polyethylene glycol to alumina slurry A, and ball mill them together at a speed of 20 rpm for 4 hours to obtain alumina slurry B.

[0074] The amount of water-based acrylic resin added is 2.0% of the mass of alumina powder, and the amount of polyethylene glycol added is 2.0% of the mass of alumina powder.

[0075] Step 3: According to the ratio, add the cationic surfactant dispersant prepared in Example 5 to alumina slurry B, and disperse it by ball milling again. The ball milling speed is 20 rpm and the ball milling time is 1 hour to obtain alumina slurry C. The amount of cationic surfactant dispersant added is 0.10% of the mass of alumina powder.

[0076] Step 4: Finally, a centrifugal spray granulation tower is used to spray granulate the alumina slurry C. The spray granulation conditions are: inlet air temperature: 280℃, outlet air temperature: 110℃, tower pressure: 50Pa, to obtain the solid spherical alumina granulated powder.

[0077] In step 1, the alumina powder has a particle size of 2.0–3.0 μm, and the sintering aids include 32 wt% SiO2, 28 wt% CaCO3, and 40 wt% talc.

[0078] Example 8

[0079] A method for preparing solid spherical alumina granulated powder includes the following steps:

[0080] Step 1: According to the ratio, first put 50wt% alumina powder, 4.5wt% sintering aid, 0.5wt% anionic surfactant dispersant prepared in Example 3 and 45wt% deionized water into a horizontal ball mill for ball milling and dispersion. The ball mill speed is 35rpm and the ball milling is carried out for 24h to obtain alumina slurry A.

[0081] Step 2: According to the ratio, add water-based acrylic resin and polyethylene glycol to alumina slurry A, and ball mill them together at a speed of 35 rpm for 2 hours to obtain alumina slurry B.

[0082] The amount of water-based acrylic resin added is 3.0% of the mass of alumina powder, and the amount of polyethylene glycol added is 3.0% of the mass of alumina powder.

[0083] Step 3: According to the ratio, add the cationic surfactant dispersant prepared in Example 5 to alumina slurry B, and ball mill and disperse it again. The ball milling speed is 35 rpm and the ball milling time is 5 h to obtain alumina slurry C. The amount of cationic surfactant dispersant added is 0.10% of the mass of alumina powder.

[0084] Step 4: Finally, a centrifugal spray granulation tower is used to spray granulate the alumina slurry C. The spray granulation conditions are: inlet air temperature: 250℃, outlet air temperature: 100℃, tower pressure: 10Pa, to obtain the solid spherical alumina granulated powder.

[0085] In step 1, the alumina powder has a particle size of 2.0 to 3.0 μm, and the sintering aids include 30 wt% SiO2, 20 wt% CaCO3, and 50 wt% talc.

[0086] Comparative Example 1

[0087] A method for preparing alumina granulated powder includes the following steps:

[0088] Step 1: According to the ratio, first put 55wt% alumina powder, 4.4wt% sintering aid and 40.6wt% deionized water into a horizontal ball mill for ball milling and dispersion. The speed of the ball mill is 20rpm and the ball milling is carried out for 12h to obtain alumina slurry A.

[0089] Step 2: According to the ratio, add water-based acrylic resin and polyethylene glycol to alumina slurry A, and ball mill them together at a speed of 20 rpm for 4 hours to obtain alumina slurry B.

[0090] The amount of water-based acrylic resin added is 2.0% of the mass of alumina powder, and the amount of polyethylene glycol added is 2.0% of the mass of alumina powder.

[0091] Step 3: Finally, a centrifugal spray granulation tower is used to spray granulate the alumina slurry B. The spray granulation conditions are: inlet air temperature: 280℃, outlet air temperature: 100℃, tower pressure: 50Pa, to obtain the alumina granulated powder.

[0092] In step 1, the alumina powder has a particle size of 2.0–3.0 μm, and the sintering aids include 32 wt% SiO2, 28 wt% CaCO3, and 40 wt% talc.

[0093] Comparative Example 2

[0094] A method for preparing alumina granulated powder includes the following steps:

[0095] Step 1: According to the ratio, first put 55wt% alumina powder, 4.4wt% sintering aid, 0.6wt% anionic surfactant dispersant prepared in Example 2 and 40wt% deionized water into a horizontal ball mill for ball milling and dispersion. The ball mill speed is 20rpm and the ball milling is carried out for 12h to obtain alumina slurry A.

[0096] Step 2: According to the ratio, add water-based acrylic resin and polyethylene glycol to alumina slurry A, and ball mill them together at a speed of 20 rpm for 4 hours to obtain alumina slurry B.

[0097] The amount of water-based acrylic resin added is 2.0% of the mass of alumina powder, and the amount of polyethylene glycol added is 2.0% of the mass of alumina powder.

[0098] Step 3: Finally, a centrifugal spray granulation tower is used to spray granulate the alumina slurry B. The spray granulation conditions are: inlet air temperature: 280℃, outlet air temperature: 110℃, tower pressure: 50Pa, to obtain the solid spherical alumina granulated powder.

[0099] In step 1, the alumina powder has a particle size of 2.0–3.0 μm, and the sintering aids include 32 wt% SiO2, 28 wt% CaCO3, and 40 wt% talc.

[0100] In the above embodiments and comparative examples, all raw materials used were commercially available.

[0101] 2. Morphological testing

[0102] Morphology images of the alumina granulated powders prepared in Example 7 and Comparative Example 1 were obtained using a Hitachi TM-4000plus electron microscope (SEM) manufactured by Hitachi, Japan, under the following conditions: test voltage: 15 kV, magnification: 200x. Figure 1 and Figure 2 As shown, the alumina granulated powder prepared in Example 7 has more complete solid spheroidization, while the alumina granulated powder prepared in Comparative Example 1 has more hemispherical shapes.

[0103] 3. Performance Testing

[0104] (1) Test method

[0105] The yield stress of the alumina slurry obtained in step 3 was measured using an Anton Paar MCR102e rheometer. The measurement conditions were: rotor diameter: 50 mm, angle: 1°, temperature: 25°C, and shear rate: 0.01–1000 s⁻¹. -1 The Casson plot model was used to simulate the curve and obtain the slurry yield stress.

[0106] Thixotropic test method for slurry:

[0107] The yield stress of the alumina slurry obtained in step 3 was measured using an Anton Paar MCR102e rheometer. The measurement conditions were: rotor diameter: 25 mm, angle: 1°, temperature: 25°C, and shear rate: 0.01–1000 s⁻¹. -1 Using the formula: Thixotropy = 5s -1 Lower viscosity / 50s -1 The viscosity was reduced to obtain the thixotropic properties of the alumina slurry.

[0108] (2) Test Results

[0109] The test results are shown in Table 1. The results show that the alumina slurry with two dispersants with opposite properties has good yield stress and thixotropy.

[0110] Table 1 Performance test results of alumina slurry

[0111]

[0112]

[0113] The above embodiments and figures are not intended to limit the product form and style of the present invention. Any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of the present invention.

Claims

1. A method for preparing solid spherical alumina granulated powder, characterized in that: Includes the following steps: Step 1: According to the formula, first put 50wt% to 60wt% alumina powder, 3wt% to 6wt% sintering aid, 0.2wt% to 0.6wt% anionic surfactant dispersant and 35wt% to 45wt% deionized water into a ball mill for ball milling and dispersion to obtain alumina slurry A; Step 2: According to the mixing ratio, add the binder and plasticizer to alumina slurry A, and then ball mill and mix to obtain alumina slurry B; The amount of the binder added is 1.0% to 3.0% of the mass of alumina powder, and the amount of the plasticizer added is 0.5% to 3.0% of the mass of alumina powder. Step 3: According to the ratio, add the cationic surfactant dispersant to the alumina slurry B, and ball mill and disperse it again to obtain alumina slurry C. The amount of cationic surfactant dispersant added is 0.05% to 0.15% of the mass of alumina powder. Step 4: Finally, the alumina slurry C is spray-granulated. The spray-granulation conditions are: inlet air temperature: 250~280℃, outlet air temperature: 100~110℃, tower pressure: -10~50Pa, to obtain the solid spherical alumina granulated powder. In step 1, the molecular structure of the anionic surfactant dispersant is shown in Formula I: In Formula I, R1 and R2 are H, COOH, and COO, respectively. - Na + COO - K + COO - NH + 4. COO - N + H(CH3)2CH2CH2OH, COO - N + One or more of H(CH2CH3)3, R3 is one of butyl, isobutyl, isooctyl and isobornyl ester, R4 is one of H and methyl; a = 0.1~0.4, b = 0.16~0.67, c = 0.23~0.44, n = 3~14, where the values ​​of a, b and c are the molar ratios of the corresponding monomers; In step 3, the molecular structure of the cationic surfactant dispersant is shown in Figure II: In Formula II, R1, R2, and R5 are one of H and methyl, respectively; R3 is one of butyl, isobutyl, isooctyl, and isobornyl; R4 is one of H and methyl; R6 is... One of CH3COOCH2CH(OH)CH2-; a = 0.1–0.4, b = 0.16–0.67, c = 0.23–0.44, n = 3–14, where a, b, and c are the molar ratios of the corresponding monomers.

2. The method for preparing solid spherical alumina granulated powder according to claim 1, characterized in that: In step 1, the alumina powder has a particle size of 2.0 to 3.0 μm, and the sintering aid includes 15 wt% to 45 wt% SiO2, 15 wt% to 23 wt% CaCO3, and 33 wt% to 70 wt% talc.

3. The method for preparing solid spherical alumina granulated powder according to claim 1, characterized in that: In step 1, the ball mill rotates at a speed of 20–35 rpm, and the ball milling time is 12–24 h.

4. The method for preparing solid spherical alumina granulated powder according to claim 1, characterized in that: In step 2, the adhesive is one of polyvinyl alcohol and water-based acrylic resin, and the plasticizer is one or both of polyethylene glycol and glycerin.

5. The method for preparing solid spherical alumina granulated powder according to claim 1, characterized in that: In step 2, the ball mill rotates at a speed of 20-35 rpm and the milling time is 2-6 hours; in step 3, the ball mill rotates at a speed of 20-35 rpm and the milling time is 1-5 hours.

6. The method for preparing solid spherical alumina granulated powder according to claim 1, characterized in that: In step 1, the preparation method of the anionic surfactant dispersant is as follows: First, add 5-30 parts of maleic anhydride or acrylic acid monomer, 23-64 parts of polyethylene glycol monoether acrylate, 20-60 parts of (meth)acrylate monomer, 0.5-5 parts of initiator, and 60-140 parts of solvent to a container in sequence, and stir evenly at room temperature to obtain a homogeneous mixed solution; then add 30-60 parts of the mixed solution to a four-necked flask, and continuously purge with nitrogen gas, raise the temperature to 75-95°C, and keep it at this temperature for 20-90 min; then add the remaining mixed solution dropwise over 0.5-4 h, and keep it at this temperature for 1-3 h; then add 30-100 parts of deionized water to cool the temperature to below 40°C, and add 5-40 parts of neutralizing reagent to carry out a neutralization reaction; after reacting for 0.5-1 h, remove the solvent by vacuum distillation to obtain the anionic surfactant dispersant.

7. The method for preparing solid spherical alumina granulated powder according to claim 6, characterized in that: The (meth)acrylate monomer is one of butyl (meth)acrylate, isobutyl (meth)acrylate, isooctyl (meth)acrylate, and isobornyl (meth)acrylate; the initiator is one of azobisisobutyronitrile and ammonium persulfate; the solvent is one or more of ethyl acetate, isopropanol, water, toluene, propylene glycol methyl ether, and butyl acetate; and the neutralizing agent is one of sodium hydroxide, potassium hydroxide, N,N-dimethylethanolamine, triethylamine, ammonia, and ammonium hydroxide.

8. The method for preparing solid spherical alumina granulated powder according to claim 1, characterized in that: In step 3, the preparation method of the cationic surfactant dispersant is as follows: First, add 5-40 parts of cationic monomer, 23-64 parts of polyethylene glycol monoether acrylate, 20-60 parts of (meth)acrylate monomer, 0.5-5 parts of initiator, and 60-140 parts of solvent to a container, and stir evenly at room temperature to obtain a homogeneous mixed solution; then add 30-60 parts of the mixed solution to a four-necked flask, and continuously purge with nitrogen gas, raise the temperature to 75-95°C, and keep it at this temperature for 20-90 min; then add the remaining mixed solution dropwise over 0.5-4 h, and keep it at this temperature for 1-3 h; then cool the temperature to below 60°C, add 5-40 parts of chloride, and continue to keep it at this temperature for 0.5-2 h; then add 20-50 parts of deionized water and cool the temperature to below 40°C; finally, add 5-40 parts of fatty acid, react for 0.5-1 h, and then remove the solvent by vacuum distillation to obtain the cationic surfactant dispersant.

9. The method for preparing solid spherical alumina granulated powder according to claim 8, characterized in that: The cationic monomer is one of dimethylaminoethyl methacrylate, N,N-dimethylacrylamide, and acrylamide; the methacrylate monomer is one of butyl methacrylate, isobutyl methacrylate, isooctyl methacrylate, and isobornyl methacrylate; the initiator is one of azobisisobutyronitrile and ammonium persulfate; the solvent is one or more of ethyl acetate, isopropanol, water, toluene, propylene glycol methyl ether, and butyl acetate; the chloride is one of methyl chloroacetate, epichlorohydrin, and chloroacetic acid; and the fatty acid is one of acetic acid, lauric acid, and stearic acid.

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