Method for directly preparing tabular corundum powder

Abstract

The invention relates to the technical field of aluminum oxide preparation, in particular to a method for directly preparing tabular corundum powder. The method comprises the following steps: carrying out first ball milling on aluminum hydroxide to obtain aluminum hydroxide particles; performing first freeze drying on the aluminum hydroxide particles to obtain pretreated aluminum hydroxide particles; dehydrating and modifying the pretreated aluminum hydroxide particles to obtain modified aluminum hydroxide particles; under the condition of preset interval duration, the modified aluminum hydroxide particles are subjected to multiple times of ball milling and grouping, and n groups of ball-milled aluminum hydroxide particles are obtained; the group number n of the ball-milled aluminum hydroxide particles meets the formula of n = T / t + 1; n > = 4 and n is an integer; carrying out secondary freeze drying on the ball-milled aluminum hydroxide particles, and sequentially hydrolyzing and filtering to obtain a filter cake; and sequentially drying and calcining the filter cake to obtain a tabular corundum powder product. According to the method, a series of fine control steps such as ball milling grouping and whole-process freeze drying are combined, and the high stacking density and the high uniformity of the tabular corundum powder can be synchronously improved.

Description

Technical Field

[0001] The present application relates to the technical field of alumina preparation, and in particular to a method for directly preparing plate-shaped corundum powder. Background Art

[0002] Corundum, also known as sintered alumina, is the most stable of the eight isomers of alumina. It has strong stability at both high and low temperatures, and corundum also has excellent mechanical properties, high temperature properties and insulation properties. In the manufacture of alumina products, corundum can reduce the shrinkage of alumina products, and is beneficial for controlling the size of alumina products and preventing the cracking of alumina products. Based on these characteristics, corundum is widely used in electronic ceramics, structural ceramics, advanced refractory materials, abrasives, grinding tools, grinding media, and lining materials for mechanical equipment. The general calcination temperature of corundum is between 1400℃ and 1600℃. When the true density of corundum reaches 3.96g / cm 3 The above situation indicates that the transformation of the γ phase to the α phase of aluminum oxide in corundum is nearly complete.

[0003] Currently, corundum raw materials, whether produced by fusion or sintering, are mostly in the form of blocks or spherical crystals, requiring processing to meet the requirements of abrasives and refractory materials. However, the processing and granulation of corundum is complex and is generally performed using a dry method. The process involves coarse crushing, intermediate crushing, and pulverization of the corundum blocks to obtain the pulverized material. The pulverized material then undergoes segmented screening, fine screening, inspection, and packaging to obtain the final corundum product.

[0004] Due to its high hardness, the crushing process requires high energy consumption and long processing time, resulting in low production efficiency and a large dust content. Furthermore, the resulting corundum powder from multiple crushing processes has a low bulk density and poor uniformity, which results in low yield and purity of the final corundum product. Summary of the Invention

[0005] The present application provides a method for directly preparing plate-shaped corundum powder to solve the following technical problem: how to simultaneously improve the bulk density and uniformity of corundum powder.

[0006] In a first aspect, an embodiment of the present application provides a method for directly preparing plate-shaped corundum powder, the method comprising:

[0007] The aluminum hydroxide is subjected to a first ball milling to obtain aluminum hydroxide particles having a predetermined particle size;

[0008] performing a first freeze-drying on the aluminum hydroxide particles having a predetermined particle size to obtain pretreated aluminum hydroxide particles;

[0009] Dehydrating and modifying the pretreated aluminum hydroxide particles to obtain modified aluminum hydroxide particles;

[0010] The modified aluminum hydroxide particles are ball-milled multiple times under a preset time interval to obtain n groups of ball-milled aluminum hydroxide particles; wherein the number n of groups of ball-milled aluminum hydroxide particles satisfies:

[0011] n=T / t+1, where T is the duration of the multiple ball milling groupings, h; t is the preset interval length, h; n≥4;

[0012] performing a second freeze-drying on the ball-milled aluminum hydroxide particles to obtain n groups of frozen aluminum hydroxide particles;

[0013] hydrolyzing n groups of the frozen aluminum hydroxide particles in sequence according to the ball milling time of the frozen aluminum hydroxide particles to obtain hydrolyzed materials;

[0014] Filtering the hydrolyzed material to obtain a filter cake;

[0015] The filter cake is dried and calcined in sequence to obtain a plate-shaped corundum powder product.

[0016] Optionally, the modified aluminum hydroxide particles are subjected to ball milling for multiple times under a preset time interval to obtain multiple groups of ball-milled aluminum hydroxide particles, comprising the steps of:

[0017] Under the conditions of a first preset feeding amount and a preset interval time, the modified aluminum hydroxide particles are subjected to a second ball milling to obtain a first group of ball-milled aluminum hydroxide particles;

[0018] Under the conditions of a second preset feeding amount and the preset interval time, a portion of the first group of ball-milled materials is subjected to a third ball milling to obtain a second group of ball-milled aluminum hydroxide particles;

[0019] Under the conditions of the third preset feeding amount and the preset interval time, a portion of the second group of ball-milled materials is subjected to a fourth ball milling to obtain a third group of ball-milled aluminum hydroxide particles;

[0020] …

[0021] Under the conditions of the nth preset feeding amount and the preset interval time, a portion of the n-1th group of ball-milled materials is subjected to the n+1th ball milling to obtain the nth group of ball-milled aluminum hydroxide particles;

[0022] The first group of ball-milled aluminum hydroxide particles, the second group of ball-milled aluminum hydroxide particles, the third group of ball-milled aluminum hydroxide particles, ... and the nth group of ball-milled aluminum hydroxide particles are collected to obtain multiple groups of ball-milled aluminum hydroxide particles.

[0023] Optionally, the first preset feeding amount is 10% to 30% of the total mass of the ball-milled aluminum hydroxide particles; and / or

[0024] The second preset feeding amount is 10% to 30% of the total mass of the ball-milled aluminum hydroxide particles; and / or

[0025] The third preset feeding amount is 10% to 30% of the total mass of the ball-milled aluminum hydroxide particles; and / or

[0026] …

[0027] The nth preset feeding amount is 10% to 30% of the total mass of the ball-milled aluminum hydroxide particles.

[0028] Optionally, the preset interval is 2 hours to 4 hours; and / or

[0029] The duration of the ball milling grouping is 12 hours to 24 hours.

[0030] Optionally, the frozen aluminum hydroxide particles include a first group of frozen aluminum hydroxide particles, a second group of frozen aluminum hydroxide particles, a third group of frozen aluminum hydroxide particles, ... and the nth group of frozen aluminum hydroxide particles;

[0031] The method comprises the following steps: hydrolyzing n groups of the frozen aluminum hydroxide particles in sequence according to the ball milling time of the frozen aluminum hydroxide particles to obtain a hydrolyzed material.

[0032] performing a first hydrolysis on the first group of frozen aluminum hydroxide particles to obtain a first group of hydrolyzed materials;

[0033] adding the second group of frozen aluminum hydroxide particles to the first group of hydrolysis materials for a second hydrolysis to obtain a second group of hydrolysis materials;

[0034] adding the third group of frozen aluminum hydroxide particles to the second group of hydrolysis materials to perform the second hydrolysis to obtain a third group of hydrolysis materials;

[0035] …

[0036] The nth group of frozen aluminum hydroxide particles is added to the n-1th group of hydrolysis material to perform the second hydrolysis to obtain a hydrolysis material.

[0037] Optionally, the duration of the first hydrolysis is twice the duration of the second hydrolysis.

[0038] Optionally, the preset particle size is 5 μm to 20 μm.

[0039] Optionally, the first ball milling time is 2h to 24h; and / or

[0040] The first freeze-drying time is 2.0h to 2.5h; and / or

[0041] The second freeze-drying time is 2.0h to 2.5h; and / or

[0042] The temperature of the dehydration modification is 950° C. to 1100° C., and the time of the dehydration modification is 0.1s to 2.0s.

[0043] Optionally, the filter cake is dried and calcined in sequence to obtain a plate-like corundum powder product, comprising the steps of:

[0044] drying the filter cake to obtain raw meal;

[0045] calcining the raw material powder to obtain an alumina calcined material;

[0046] The alumina calcined material is subjected to a second calcination to obtain plate-like alumina powder.

[0047] Optionally, the drying temperature is 90° C. to 120° C.; and / or

[0048] The temperature of the first calcination is 980° C. to 1020° C., and the time of the first calcination is 2 h to 3 h; and / or

[0049] The temperature of the second calcination is 1900° C. to 1940° C., and the time of the first calcination is 2 hours to 3 hours.

[0050] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0051] The present application embodiment provides a method for directly preparing plate-like corundum powder, which firstly makes aluminum hydroxide reach a preset particle size by the first ball milling, facilitates the subsequent multiple ball milling grouping, and then optimizes the distribution uniformity of aluminum hydroxide particles by the first freeze drying, and optimizes the precursor structure of aluminum hydroxide by dehydration modification, which can facilitate the subsequent ball milling grouping. In the ball milling grouping stage, within the total duration T of the ball milling grouping, a batch of materials is taken out at a fixed interval of time t, and aluminum hydroxide particles with different ball milling times can be obtained. The particle size distribution of these aluminum hydroxide particles is relatively concentrated, and the uniform growth of crystal grains can be controlled in the subsequent hydrolysis and calcination process; in addition, these aluminum hydroxide particles are arranged according to the time of ball milling grouping, and the ball milling aluminum hydroxide particles taken out earlier are coarser, while the ball milling aluminum hydroxide particles taken out later are finer. In the process of hydrolysis arranged in sequence according to the time of taking out, the finer ball milling aluminum hydroxide particles can be filled into the gaps of the coarser ball milling aluminum hydroxide particles, and the bulk density between the ball milling aluminum hydroxide particles is improved by grading of different particle sizes. In addition, during the hydrolysis stage, ball-milled aluminum hydroxide particles of different coarseness and fineness are hydrolyzed in the order of the time of grinding grouping, which can accurately control the degree of hydrolysis of each group of ball-milled aluminum hydroxide particles to form a more uniform hydrolysis material. These high-packing density and high-uniformity hydrolysis materials can promote the transformation of γ-Al2O3 into flaky α-Al2O3 after subsequent drying and calcination. At the same time, the formed α-Al2O3 can form a dense plate-like corundum powder product through staggering and overlapping. Therefore, this method simultaneously improves the packing density and distribution uniformity of the plate-like corundum powder through the mechanism strategies of "grading to improve packing density-suppressing agglomeration to ensure uniformity and grading-precursor uniformity to ensure final uniformity-plate-like morphology to synergistically improve density". BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0053] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0054] Figure 1 A schematic diagram of the main flow chart of a method for directly preparing plate-shaped corundum powder provided in an embodiment of the present application;

[0055] Figure 2 A schematic diagram of a detailed process of a method for directly preparing plate-shaped corundum powder provided in an embodiment of the present application;

[0056] Figure 3 for Figure 2 Continuation of

[0057] Figure 4 A schematic diagram of the actual process of a method for directly preparing plate-shaped corundum powder provided in an embodiment of the present application. DETAILED DESCRIPTION

[0058] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0059] The range descriptions described in this application, such as numerical ranges, ratio ranges, etc., include all possible sub-ranges and single numerical values ​​within the range. For example, the range description of "1 to 6" or "1~6" covers all sub-ranges from 1 to 6 (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6). Unless otherwise specified, the terms "including" and "including" used in this article mean "including but not limited to"; relational terms such as "first" and "second" are only used to distinguish different entities or operations, and do not imply an actual sequence or association relationship; "and / or" means that multiple situations can exist alone or simultaneously; expressions such as "at least one", "multiple", and "at least one" refer to any combination of corresponding objects, including a combination of single or multiple objects. The proportional relationships involved in the text, such as mass ratios, molar ratios, etc., should be understood as the corresponding relationship between the first and second terms of the proportional formula in the order of description. The raw materials, reagents, instruments and equipment used in this article can be purchased on the market or prepared by existing methods.

[0060] It should be noted that there are two main methods for the production process of corundum at this stage: (1) Method 1: industrial alumina, converter and additive are mixed to form a mixture; these mixtures are then mixed with binder and water to obtain production raw materials; these production raw materials are successively subjected to ball forming, kiln loading, firing, crushing, iron removal, quality inspection and analysis confirmation to obtain finished sintered alumina; (2) Method 2: industrial alumina, converter and additive are mixed to obtain a mixture; then the mixture is successively subjected to mixing and fine grinding, kiln loading, kiln loading, firing, kiln discharge, quality inspection and analysis confirmation to obtain finished sintered alumina. However, both methods will add additives such as converters and additives. The role of these additives can reduce the transformation temperature of the crystal form, accelerate the transformation speed of the alumina phase change, and even reduce the impurities in the raw materials. For example, adding mineralizers to the raw materials can reduce the phase transition temperature of gibbsite from 1270°C to 1337°C to 1015°C to 1065°C, and at the same time reduce the phase transition temperature of diaspore from 1245°C to 1310°C to 1213°C to 1285°C. In addition, the conversion rate of α-phase alumina in corundum can be increased to more than 98%, and the true density of corundum can be increased to 3.95g / cm 3 In addition, the addition of mineralizers can lower the firing temperature of certain alumina products while maintaining the sintering activity of α-phase alumina. For example, the firing temperature of alumina can be reduced to below 1450°C. However, the addition of mineralizers can reduce the performance of corundum, resulting in the formation of mostly massive or spherical crystals.

[0061] However, corundum in the form of massive or spherical crystals must be processed to meet the requirements for use as abrasives and refractory materials. This process typically involves multiple crushing steps, which consumes high energy and takes a long time. This results in low corundum powder production efficiency and a large dust content. Furthermore, the resulting corundum powder has a low bulk density and poor uniformity, resulting in low yield and purity of the final corundum product.

[0062] Figure 1 The following is a schematic flow chart of a method for directly preparing plate-shaped corundum powder provided in an embodiment of the present application;

[0063] Figure 4 The actual process diagram of a method for directly preparing plate-shaped corundum powder provided in an embodiment of the present application is exemplarily shown.

[0064] like Figure 1 and Figure 4 As shown, the embodiment of the present application provides a method for directly preparing plate-shaped corundum powder, the method comprising:

[0065] S1. The aluminum hydroxide is first ball-milled to obtain aluminum hydroxide particles having a predetermined particle size;

[0066] S2. The aluminum hydroxide particles having a predetermined particle size are subjected to a first freeze-drying to obtain pretreated aluminum hydroxide particles;

[0067] S3. The pretreated aluminum hydroxide particles are dehydrated and modified to obtain modified aluminum hydroxide particles;

[0068] S4. The modified aluminum hydroxide particles are ball-milled multiple times under a preset interval to obtain n groups of ball-milled aluminum hydroxide particles; wherein the number n of groups of ball-milled aluminum hydroxide particles satisfies:

[0069] n=T / t+1, where T is the duration of the multiple ball milling groupings, h; t is the preset interval length, h; n≥4;

[0070] S5. The ball-milled aluminum hydroxide particles are subjected to a second freeze-drying to obtain n groups of frozen aluminum hydroxide particles;

[0071] S6. According to the size of the ball milling time of the frozen aluminum hydroxide particles, the n groups of frozen aluminum hydroxide particles are sequentially hydrolyzed to obtain a hydrolyzed material;

[0072] S7. The hydrolyzed material is filtered to obtain a filter cake;

[0073] S8. drying and calcining the filter cake in sequence to obtain a plate-like corundum powder product.

[0074] It should be noted that the ball milling grouping is to grind and group the modified aluminum hydroxide particles in batches at preset intervals.

[0075] It should be noted that the formula n=T / t+1 means that the value of n is an integer of the overall value (T / t+1), for example, n=13 / 2+1=7.5=7, n=12 / 2+1=7=7.

[0076] It should be noted that the temperature of the first freeze-drying process may be between -50°C and 0°C; and the temperature of the second freeze-drying process may be between -40°C and 0°C.

[0077] It should be noted that the present invention provides a method for directly preparing tabular corundum powder. This method, through a series of carefully controlled steps, simultaneously improves the bulk density and uniformity of the final tabular corundum powder. The core mechanism is as follows:

[0078] 1. Accurately control the initial particle size (first ball milling):

[0079] Purpose: To ensure that the starting material (aluminum hydroxide) has a predetermined particle size.

[0080] (1) Effect on uniformity: It provides a uniform and consistent base material for all subsequent processing steps, reducing the inconsistency of subsequent processing effects caused by large differences in initial particle size.

[0081] (2) Effect on bulk density: A suitable initial particle size is the basis for obtaining an ideal gradation. An initial particle size that is too large or too small is not conducive to forming a good bulk density in subsequent graded ball milling.

[0082] 2. Prevent initial agglomeration (first freeze drying):

[0083] Purpose: To remove moisture from ball-milled aluminum hydroxide particles and avoid hard agglomeration caused by conventional drying (such as hot air drying).

[0084] (1) Effect on uniformity: Freeze drying can maintain the state of individual particles obtained after ball milling to the greatest extent, preventing them from sticking together due to capillary forces during the drying process to form hard agglomerates that are difficult to disperse, thereby ensuring the dispersibility and initial uniformity of the pretreated aluminum hydroxide particles.

[0085] (2) Effect on bulk density: Individual dispersed particles are easier to achieve dense arrangement in subsequent processing and final stacking than hard agglomerates. Hard agglomerates have many internal pores that are difficult to fill, which will significantly reduce the bulk density.

[0086] 3. Optimize the precursor structure (dehydration modification):

[0087] Purpose: To convert aluminum hydroxide Al(OH)3 into aluminum oxide precursor.

[0088] (1) Effect on uniformity: By controlling the dehydration conditions (temperature, atmosphere, time, etc.), alumina precursor particles with relatively uniform structure, phase and activity are obtained. This structural uniformity is crucial for uniform reaction and grain growth during the subsequent hydrolysis and calcination processes.

[0089] (2) Effect on bulk density: The modified aluminum hydroxide particles after dehydration modification usually have a more stable structure and a morphology that is more conducive to subsequent processing (such as flaky aluminum oxide), which lays the foundation for the final formation of plate-like corundum and dense stacking.

[0090] 4. Gradual ball milling (multiple ball milling groups):

[0091] Purpose: Within a total duration T, a batch of material is taken out at fixed intervals of time t to obtain a total of n groups (n = T / t + 1, n ≥ 4) of particles that have undergone different cumulative ball milling times.

[0092] (1) Effect on uniformity:

[0093] This avoids over-grinding and excessively wide particle size distribution of the modified aluminum hydroxide particles caused by a single, long-term ball milling process. Over-grinding will produce a large number of extremely fine particles (submicron or nanometer level). These particles have high surface energy and are very easy to agglomerate. Various reaction behaviors during the hydrolysis and calcination processes are difficult to control (such as abnormal growth), which will destroy the overall uniformity of the corundum powder product.

[0094] After a specific and limited ball milling time, the particle size distribution inside each group of ball-milled aluminum hydroxide particles is relatively concentrated.

[0095] (2) Effect on bulk density:

[0096] Different groups of ball-milled aluminum hydroxide particles have different average particle sizes and particle size distributions. The particles of the group taken out earlier (shorter ball-milling time) are coarser; the particles of the group taken out later (longer ball-milling time) are finer.

[0097] Based on the good gradation formed by the ball-milled aluminum hydroxide particles of different particle sizes and particle size distributions, the hydrolyzed materials are hydrolyzed in sequence according to the ball-milling time, and then the filter cakes obtained by filtering these hydrolyzed materials are a mixture of all the hydrolyzed materials. These mixtures can be naturally mixed in the subsequent calcination process and stacked to form a dense plate-like corundum powder product.

[0098] (3) Grading principle: Finer particles can fill the gaps between coarser particles, thereby significantly reducing the total pore volume in the particle stacking system.

[0099] n≥4 ensures that there are enough "particle size grades" to achieve a more optimized filling effect, making the ball-milled aluminum hydroxide particles more densely packed and greatly improving the packing density.

[0100] 5. Maintaining the grading effect (second freeze drying):

[0101] Purpose: To remove moisture from each group of particles after ball milling.

[0102] (1) Effect on uniformity: Freeze drying can prevent the hard agglomeration of each group of ball-milled aluminum hydroxide particles (especially the fine particle group) during the drying process, thereby maintaining the dispersion of the ball-milled aluminum hydroxide particles in each group and the specific particle size distribution state obtained after ball milling.

[0103] (2) Effect on bulk density: Maintaining the dispersion state and original particle size of each group of ball-milled aluminum hydroxide particles is the prerequisite for achieving the graded filling effect. If drying causes severe agglomeration, the fine particles cannot effectively fill the gaps between the coarse particles, resulting in the loss of the graded advantage between the particles.

[0104] 6. Sequential hydrolysis:

[0105] Purpose: To hydrolyze frozen aluminum hydroxide in order according to particle size (ball milling time represents particle size).

[0106] (1) Effect on uniformity: Frozen aluminum hydroxide particles of different particle sizes may have different specific surface areas and reactivity. Hydrolysis in order of particle size (maybe from coarse to fine or vice versa, depending on the specific process design) helps to more accurately control the degree of hydrolysis of each group of frozen aluminum hydroxide particles, so that each group of frozen aluminum hydroxide particles undergoes a more uniform hydrolysis treatment and obtains a hydrolysis product (hydrated aluminum oxide) with more uniform chemical properties. This lays the foundation for the final calcination to obtain uniform corundum grains.

[0107] (2) Effect on bulk density: ensuring that the hydrolysis process does not destroy or change the particle size distribution characteristics of different groups of frozen aluminum hydroxide particles, thereby retaining the particle size differences used for the final grading.

[0108] 7. Molding and densification (filtration, drying, calcination):

[0109] (1) Filtration: Separate the solid and liquid of the hydrolyzed material to obtain a filter cake (hydrated alumina precursor). The stacking structure of the filter cake initially reflects the grading effect.

[0110] (2) Drying: Gently remove residual moisture to prevent rapid drying that may cause cracking or agglomeration.

[0111] (3) Calcination: Under high temperature conditions, the hydrated alumina precursor dehydrates, undergoes a phase change (γ-Al2O3→α-Al2O3) and is sintered into a shape.

[0112] (3) Effect on uniformity: Chemical and structural uniformity of the precursor (due to dehydration modification and sequential hydrolysis) is the key to obtaining corundum powder with uniform grain size and morphology (plate-like). A uniform precursor reacts more consistently under the same calcination conditions.

[0113] (4) Effect on packing density: The good gradation and tight packing of the precursor particles are maintained and strengthened during the calcination process.

[0114] (5) Plate-like morphology: Under specific calcination conditions, corundum grains develop into plate-like shapes. Compared to equiaxed particles (e.g., spherical particles), plate-like corundum powders can achieve denser packing through the interlacing and overlapping of plates, further increasing the packing density. Sintering during the calcination process also results in closer contact between particles.

[0115] In summary, the embodiments of the present application provide a method for directly preparing tabular corundum powder, which simultaneously improves the bulk density and distribution uniformity of the tabular corundum powder through the following mechanisms:

[0116] (1) Grading to improve packing density: Through the process of "multiple ball milling and grouping", multiple groups of ball-milled aluminum hydroxide particles with different average particle sizes and distributions are creatively produced. After these different groups of ball-milled aluminum hydroxide are finally mixed, the coarser particles form the skeleton, while the finer particles fill the gaps, achieving dense packing. And n ≥ 4 ensures the fineness of the gradation.

[0117] (2) Suppressing agglomeration to ensure uniformity and gradation: Two freeze-drying steps are performed throughout the process to prevent the formation of hard agglomerates to the greatest extent possible. This not only ensures the uniformity of individual particles, but more importantly, maintains the particle size differences produced by graded ball milling, enabling effective gradation and filling.

[0118] (3) Precursor uniformity ensures final uniformity: the “dehydration modification” step optimizes the precursor structure, and the “sequential hydrolysis” step ensures the uniformity of the reaction of particles of different particle sizes. This provides the basis for calcining to obtain corundum powder with uniform grain size and plate-like morphology.

[0119] (4) Plate-like morphology synergistically improves density: The final calcination process forms plate-like grains while obtaining α-Al2O3. This specific morphology further optimizes the particle stacking method, and through the stacking and interlacing of plates, it can improve the packing density more than spherical particles.

[0120] Therefore, the embodiment of the present application provides a method for directly preparing plate-like corundum powder. This method cleverly achieves the simultaneous improvement of high bulk density and high uniformity of plate-like corundum powder through the two core strategies of "graded ball milling to produce gradation" and "full freeze-drying to inhibit agglomeration", supplemented by the control of precursor uniformity and regulation of the final product morphology.

[0121] Figure 2 A detailed flow chart of a method for directly preparing plate-shaped corundum powder provided in an embodiment of the present application is shown as an example;

[0122] In some optional embodiments, such as Figure 2 As shown, the modified aluminum hydroxide particles are ball-milled and grouped multiple times under a preset interval to obtain multiple groups of ball-milled aluminum hydroxide particles, including the steps of:

[0123] S401. Under the conditions of a first preset feeding amount and a preset interval length, the modified aluminum hydroxide particles are subjected to a second ball milling to obtain a first group of ball-milled aluminum hydroxide particles;

[0124] S402. Under the conditions of the second preset feeding amount and the preset interval length, a portion of the first group of ball-milled materials is subjected to a third ball milling to obtain a second group of ball-milled aluminum hydroxide particles;

[0125] S403. Under the conditions of the third preset feeding amount and the preset interval length, a portion of the second group of ball-milled materials is subjected to a fourth ball milling to obtain a third group of ball-milled aluminum hydroxide particles;

[0126] …

[0127] S404. Under the conditions of the nth preset feeding amount and the preset interval length, part of the n-1th group of ball milling materials is subjected to the n+1th ball milling to obtain the nth group of ball-milled aluminum hydroxide particles;

[0128] S405. Collect the first group of ball-milled aluminum hydroxide particles, the second group of ball-milled aluminum hydroxide particles, the third group of ball-milled aluminum hydroxide particles, ... and the nth group of ball-milled aluminum hydroxide particles to obtain multiple groups of ball-milled aluminum hydroxide particles.

[0129] In these embodiments, by setting specific feed amounts and intervals for grinding and grouping the modified aluminum hydroxide particles, modified aluminum hydroxide particles from different grinding time periods can be collected, thereby producing ball-milled aluminum hydroxide particles with different average particle sizes and particle size distributions. These ball-milled aluminum hydroxide particles of different particle sizes will exhibit a grading effect during subsequent processing, and through specific post-processing steps, a plate-shaped corundum powder product with a higher bulk density can be produced.

[0130] In some optional embodiments, the first preset feeding amount is 10% to 30% of the total mass of the ball-milled aluminum hydroxide particles; and / or

[0131] The second preset feeding amount is 10% to 30% of the total mass of the ball-milled aluminum hydroxide particles; and / or

[0132] The third preset feeding amount is 10% to 30% of the total mass of the ball-milled aluminum hydroxide particles; and / or

[0133] …

[0134] The nth preset feeding amount is 10% to 30% of the total mass of the ball-milled aluminum hydroxide particles.

[0135] In these embodiments, the first preset feeding amount, the second preset feeding amount, the third preset feeding amount... and the nth preset feeding amount, which are 10% to 30% of the mass of the modified aluminum hydroxide particles, can make the ball-milled aluminum hydroxide particles in different groups evenly distributed, so as to improve the stacking effect between the ball-milled aluminum hydroxide particles of different particle sizes, and after subsequent processing, a plate-shaped corundum powder product with a higher stacking density can be obtained.

[0136] The first preset feeding amount can be 10%, 15%, 20%, 25% or 30% of the total mass of the ball-milled aluminum hydroxide particles.

[0137] The second preset feeding amount can be 10%, 15%, 20%, 25% or 30% of the total mass of the ball-milled aluminum hydroxide particles.

[0138] The third preset feeding amount can be 10%, 15%, 20%, 25% or 30% of the total mass of the ball-milled aluminum hydroxide particles.

[0139] The nth preset feeding amount can be 10%, 15%, 20%, 25% or 30% of the total mass of the ball-milled aluminum hydroxide particles.

[0140] In some optional implementations, the preset interval duration is 2 hours to 4 hours; and / or

[0141] The duration of the ball milling grouping is 12 hours to 24 hours.

[0142] In these embodiments, by setting a preset interval length of 2 to 4 hours and a grinding group duration of 12 to 24 hours, the number of grinding groups can be precisely controlled to no more than 13, thereby achieving a refined distribution of ball-milled aluminum hydroxide particles. This process enhances the distribution differences between different ball-milled aluminum hydroxide particles and promotes the gradation phenomenon between particles. After subsequent processing, a plate-shaped corundum powder product with a high bulk density can be obtained.

[0143] The preset interval duration may be 2 hours, 2.5 hours, 3.0 hours, 3.5 hours or 4.0 hours.

[0144] The duration of the ball milling grouping can be 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours or 24 hours.

[0145] In some optional embodiments, the frozen aluminum hydroxide particles include a first group of frozen aluminum hydroxide particles, a second group of frozen aluminum hydroxide particles, a third group of frozen aluminum hydroxide particles, ... and the nth group of frozen aluminum hydroxide particles;

[0146] The method comprises the following steps: hydrolyzing n groups of the frozen aluminum hydroxide particles in sequence according to the ball milling time of the frozen aluminum hydroxide particles to obtain a hydrolyzed material.

[0147] S601. performing a first hydrolysis on the first group of frozen aluminum hydroxide particles to obtain a first group of hydrolyzed materials;

[0148] S602. adding the second group of frozen aluminum hydroxide particles to the first group of hydrolyzed materials for a second hydrolysis to obtain a second group of hydrolyzed materials;

[0149] S603. Adding the third group of frozen aluminum hydroxide particles to the second group of hydrolyzed materials to perform the second hydrolysis to obtain a third group of hydrolyzed materials;

[0150] …

[0151] S604. Add the nth group of frozen aluminum hydroxide particles to the n-1th group of hydrolysis material to perform the second hydrolysis to obtain a hydrolysis material.

[0152] In these embodiments, a subsequent group of frozen aluminum hydroxide particles is sequentially added to the previous group of hydrolyzed materials to perform a second-stage hydrolysis process, thereby obtaining multiple groups of hydrolyzed materials. This method, through sequential hydrolysis steps, allows for more precise control of the degree of hydrolysis of each group of frozen aluminum hydroxide particles, ensuring that each group of particles undergoes a homogeneous hydrolysis process, thereby producing a hydrolyzed product with consistent chemical properties. This facilitates the formation of a uniform, tabular corundum powder product during the subsequent calcination process.

[0153] In some optional embodiments, the duration of the first hydrolysis is twice the duration of the second hydrolysis.

[0154] In these embodiments, by setting the duration of the primary hydrolysis to twice the duration of the secondary hydrolysis, sufficient primary hydrolysis products can be formed during the primary hydrolysis process, thereby facilitating the subsequent sequential hydrolysis of the frozen aluminum hydroxide particles, thereby generating hydrolysis products with more uniform chemical properties. This is beneficial for forming a uniform plate-like α-Al2O3 powder product during the subsequent calcination process.

[0155] In some optional embodiments, the preset particle size is 5 μm to 20 μm.

[0156] In these embodiments, the aluminum hydroxide particles are set to have a particle size range of 5 μm to 20 μm, which can ensure that their specific surface area is small enough to facilitate the subsequent grinding grouping and sequential hydrolysis process, and finally calcine a uniform plate-shaped corundum powder product with a high bulk density.

[0157] The predetermined particle size may be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 15 μm or 20 μm.

[0158] In some optional embodiments, the first ball milling time is 2 hours to 24 hours; and / or

[0159] The first freeze-drying time is 2.0h to 2.5h; and / or

[0160] The second freeze-drying time is 2.0h to 2.5h; and / or

[0161] The temperature of the dehydration modification is 950° C. to 1100° C., and the time of the dehydration modification is 0.1s to 2.0s.

[0162] In these embodiments, the first ball milling time is controlled within the range of 2 to 24 hours to ensure that the aluminum hydroxide particles are fully ground to a preset particle size. The first freeze-drying time is maintained at 2.0 to 2.5 hours, which helps to remove moisture from the aluminum hydroxide particles after ball milling and prevent particles from agglomerating during the pretreatment process, thereby affecting the uniformity of the ball milling grouping. The second freeze-drying also lasts for 2.0 to 2.5 hours to effectively remove moisture from the ball-milled aluminum hydroxide particles, forming evenly distributed frozen aluminum hydroxide particles, and creating favorable conditions for subsequent calcination to prepare a high-packing density plate-shaped corundum powder product. In addition, by performing a dehydration modification treatment for 0.1 to 2.0 seconds within a temperature range of 950°C to 1100°C, moisture in the pretreated aluminum hydroxide particles can be effectively removed, particle agglomeration can be prevented, and the uniformity of the ball milling grouping can be ensured; at the same time, this process can also promote the conversion of aluminum hydroxide particles to alumina precursors.

[0163] The first ball milling time can be 2 h, 4 h, 6 h, 8 h, 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h or 24 h.

[0164] The first freeze-drying time can be 2.0 h, 2.1 h, 2.2 h, 2.3 h, 2.4 h or 2.5 h.

[0165] The second freeze-drying time can be 2.0 h, 2.1 h, 2.2 h, 2.3 h, 2.4 h or 2.5 h.

[0166] The temperature of the dehydration modification may be 950°C, 960°C, 970°C, 980°C, 990°C, 1000°C, 1010°C, 1020°C, 1030°C, 1040°C, 1050°C, 1060°C, 1070°C, 1080°C, 1090°C or 1000°C.

[0167] The dehydration modification time can be 0.1s, 0.2s, 0.3s, 0.4s, 0.5s, 1.0s, 1.5s or 2.0s.

[0168] In some optional embodiments, the filter cake is dried and calcined in sequence to obtain a plate-like corundum powder product, comprising the steps of:

[0169] S801. The filter cake is dried to obtain raw meal;

[0170] S802. The raw material powder is first calcined to obtain an alumina calcined material;

[0171] S803. Calcine the alumina calcined material for the second time to obtain plate-like alumina powder.

[0172] In these embodiments, the filter cake is dried to effectively remove residual moisture therein, thereby avoiding cracks or agglomeration caused by an excessively fast drying rate, thereby obtaining raw material powder; subsequently, through a primary calcination process, the hydrated alumina precursor is dehydrated, and its initial phase change and sintering are promoted to form, thereby obtaining an alumina calcined material; finally, through a secondary calcination, the alumina calcined material is fully phase-changed, prompting the corundum grains to develop into a plate-like structure. At the same time, the plate-like corundum grains are interlaced and overlapped to form a more compact plate-like corundum powder product.

[0173] In some optional embodiments, the drying temperature is 90° C. to 120° C.; and / or

[0174] The temperature of the first calcination is 980° C. to 1020° C., and the time of the first calcination is 2 h to 3 h; and / or

[0175] The temperature of the second calcination is 1900° C. to 1940° C., and the time of the first calcination is 2 hours to 3 hours.

[0176] In these embodiments, the drying process carried out in the temperature range of 90°C to 120°C can remove the residual moisture in the filter cake in a relatively gentle manner, effectively avoiding the cracking or agglomeration of the filter cake caused by an excessively fast drying rate, thereby obtaining a raw material powder with good dispersibility. Furthermore, the temperature range of 980°C to 1020°C and the holding time of 2h to 3h are used in the first calcination stage to promote the dehydration reaction of the hydrated alumina precursor and induce its initial phase change and sintering. In addition, the high temperature of 1900°C to 1940°C and the holding time of 2h to 3h in the second calcination stage can fully complete the phase change of the alumina calcined material, promote the development of the corundum grains into a plate-like structure, and form a more compact plate corundum powder product through the mutual interlacing and overlapping of the plate-like corundum particles.

[0177] The drying temperature may be 90°C, 95°C, 100°C, 105°C, 110°C, 115°C or 120°C.

[0178] The temperature of the first calcination may be 980°C, 985°C, 990°C, 995°C, 100°C, 105°C, 110°C, 115°C or 120°C.

[0179] The time of the first calcination may be 2.0 h, 2.1 h, 2.2 h, 2.3 h, 2.4 h, 2.5 h, 2.6 h, 2.7 h, 2.8 h, 2.9 h or 3.0 h.

[0180] The temperature of the second calcination may be 1900°C, 1905°C, 1910°C, 1915°C, 1920°C, 1925°C, 1930°C, 1935°C, or 1940°C.

[0181] The time of the second calcination may be 2.0 h, 2.1 h, 2.2 h, 2.3 h, 2.4 h, 2.5 h, 2.6 h, 2.7 h, 2.8 h, 2.9 h or 3.0 h.

[0182] The present application is further described below with reference to specific examples. Experimental methods in the following examples where specific conditions are not specified are generally measured in accordance with national / industry standards. If there are no corresponding national / industry standards, the methods are carried out in accordance with commonly used international standards, conventional conditions, or conditions recommended by the manufacturer.

[0183] Example 1

[0184] like Figure 1 As shown, a method for directly preparing plate-shaped corundum powder comprises:

[0185] S1. The aluminum hydroxide is first ball-milled to obtain aluminum hydroxide particles having a predetermined particle size;

[0186] S2. The aluminum hydroxide particles having a preset particle size are first freeze-dried to obtain pretreated aluminum hydroxide particles;

[0187] S3. The pretreated aluminum hydroxide particles are dehydrated and modified to obtain modified aluminum hydroxide particles;

[0188] S401. Under the conditions of a first preset feed amount and a preset interval length, the modified aluminum hydroxide particles are subjected to a second ball milling 0h to obtain a first group of ball-milled aluminum hydroxide particles AH-0;

[0189] S402. Under the conditions of a second preset feed amount and a preset interval length, a portion of the first group of ball-milled materials is subjected to a third ball milling for 3 hours to obtain a second group of ball-milled aluminum hydroxide particles AH-3;

[0190] S403. Under the conditions of the third preset feeding amount and the preset interval length, part of the second group of ball-milled materials was subjected to a fourth ball milling for 3 hours to obtain a third group of ball-milled aluminum hydroxide particles AH-6;

[0191] …

[0192] S404. Under the conditions of the fourth preset feeding amount and the preset interval length, part of the fourth group of ball-milled materials was subjected to the sixth ball milling for 3 hours to obtain the fifth group of ball-milled aluminum hydroxide particles AH-12;

[0193] S405. Collect the first group of ball-milled aluminum hydroxide particles, the second group of ball-milled aluminum hydroxide particles, the third group of ball-milled aluminum hydroxide particles ... and the fifth group of ball-milled aluminum hydroxide particles to obtain multiple groups of ball-milled aluminum hydroxide particles;

[0194] S5. The multiple groups of ball-milled aluminum hydroxide particles were subjected to a second freeze-drying to obtain five groups of frozen aluminum hydroxide particles;

[0195] S601. The first group of frozen aluminum hydroxide particles is subjected to a first hydrolysis to obtain a first group of hydrolyzed materials, designated as 0# slurry;

[0196] S602. A second group of frozen aluminum hydroxide particles is added to the first group of hydrolyzed materials in a preset amount for a second hydrolysis to obtain a second group of hydrolyzed materials, designated as slurry #3;

[0197] S603. The third group of frozen aluminum hydroxide particles is added to the second group of hydrolyzed material for a second hydrolysis to obtain a third group of hydrolyzed material, recorded as slurry #6;

[0198] …

[0199] S604. The fifth group of frozen aluminum hydroxide particles is added to the fourth group of hydrolyzed materials in a preset amount for a second hydrolysis to obtain a hydrolyzed material, which is designated as slurry 12#;

[0200] S7. The hydrolyzed material is filtered to obtain a filter cake;

[0201] S801. The filter cake is dried to obtain raw meal;

[0202] S802. The raw material powder is first calcined to obtain an alumina calcined material;

[0203] S803. Carry out a second calcination of the alumina calcined material to obtain plate-like alumina powder.

[0204] The preset interval length is 3h;

[0205] The duration of ball milling was 12 h.

[0206] The first preset feeding amount is 10% of the total mass of the ball-milled aluminum hydroxide particles;

[0207] The second preset feeding amount is 20% of the total mass of the ball-milled aluminum hydroxide particles;

[0208] The third preset feeding amount is 30% of the total mass of the ball-milled aluminum hydroxide particles;

[0209] The fourth preset feeding amount is 20% of the total mass of the ball-milled aluminum hydroxide particles;

[0210] The fifth preset feeding amount is 20% of the total mass of the ball-milled aluminum hydroxide particles.

[0211] The duration of the first hydrolysis was 1.0 h

[0212] The duration of the second hydrolysis was 0.5 h.

[0213] The preset particle size is 5μm to 20μm;

[0214] The first ball milling time is 2h to 24h;

[0215] The first freeze-drying time was 2.0 h;

[0216] The second freeze-drying time was 2.0 h;

[0217] The temperature of the dehydration modification is 950° C. to 1100° C., and the time of the dehydration modification is 0.1s to 2.0s.

[0218] The drying temperature is 120℃;

[0219] The temperature of the first calcination is 1000°C, and the time of the first calcination is 2h;

[0220] The temperature of the second calcination was 1900° C., and the time of the first calcination was 2 h.

[0221] Example 2

[0222] Compared with Example 1, this embodiment has the following differences, and the rest are the same:

[0223] The first preset feeding amount is 10% of the total mass of the ball-milled aluminum hydroxide particles;

[0224] The second preset feeding amount is 20% of the total mass of the ball-milled aluminum hydroxide particles;

[0225] The third preset feeding amount is 20% of the total mass of the ball-milled aluminum hydroxide particles;

[0226] The fourth preset feeding amount is 20% of the total mass of the ball-milled aluminum hydroxide particles;

[0227] The fifth preset feeding amount is 20% of the total mass of the ball-milled aluminum hydroxide particles.

[0228] The sixth group was set to feed 10% of the total mass of the ball-milled aluminum hydroxide particles.

[0229] The preset interval length is 4 hours;

[0230] The duration of ball milling was 20 h.

[0231] Comparative Example 1

[0232] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0233] The modified aluminum hydroxide particles were directly subjected to the second ball milling for 0 h without grinding and grouping.

[0234] Comparative Example 2

[0235] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0236] The modified aluminum hydroxide particles were directly ball-milled for 3 h without grinding and grouping.

[0237] Comparative Example 3

[0238] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0239] The modified aluminum hydroxide particles were directly ball-milled for 6 h without grinding and grouping.

[0240] Comparative Example 4

[0241] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0242] The modified aluminum hydroxide particles were directly ball-milled for 9 h without grinding and grouping.

[0243] Comparative Example 5

[0244] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0245] The modified aluminum hydroxide particles were directly ball-milled for 12 h without grinding and grouping.

[0246] Related experiments and effect data:

[0247] The chemical properties, physical properties and characterization structures of the plate-like corundum powder products of each embodiment and comparative example were collected respectively, and the results are shown in Table 1.

[0248] Table 1 Performance of plate-shaped corundum powder products of various embodiments and comparative examples

[0249]

[0250] As shown in Table 1, the method for directly preparing plate-shaped corundum powder provided in the embodiment of the present application adopts the two core strategies of "gradation by graded ball milling" and "full freeze drying to inhibit agglomeration", supplemented by the control of precursor homogeneity and the regulation of the morphology of the final product, so that the volume density of the final plate-shaped corundum powder product can reach 3.80 g / cm 3 The final average grain size is above 380 μm, which shows that the plate-shaped corundum powder product has a high bulk density and uniformity.

[0251] In addition, compared with Example 1, Comparative Examples 1 to Comparative Examples 5 all use a single particle size. Although the longer the grinding time, the bulk density and average grain size are similar to those of the embodiment, the volume density is difficult to reach 3.80 g / cm 3 The above, at the same time, the uniformity is poor.

[0252] In summary, the embodiments of the present application provide a method for directly preparing tabular corundum powder. This method combines the two operating steps of ball milling grouping and full freeze-drying, supplemented by the control of precursor uniformity and the regulation of the final product morphology, which can simultaneously improve the high packing density and high uniformity of the tabular corundum powder.

[0253] In addition, the embodiment of the present application provides a method for directly preparing plate-shaped corundum powder. This method can also press the filter cake through molds with different pore sizes to form filter cake particles of different particle sizes, or prepare filter cake particles of different particle sizes through a rolling drum, and finally obtain plate-shaped corundum powder products of different particle sizes.

[0254] In addition, the embodiments of the present application provide a method for directly preparing plate-shaped corundum powder. The plate-shaped corundum powder product prepared by this method has good bulk density and uniformity, and can be directly applied to many fields such as electronic ceramics, structural ceramics, advanced refractory materials, abrasives, grinding tools, grinding media, mechanical equipment, etc. with different particle size requirements.

[0255] The foregoing is merely a detailed description of the present invention, intended to enable those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but rather is intended to conform to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for directly preparing plate-shaped corundum powder, the method comprising: The aluminum hydroxide is subjected to a first ball milling to obtain aluminum hydroxide particles having a predetermined particle size; performing a first freeze-drying on the aluminum hydroxide particles having a predetermined particle size to obtain pretreated aluminum hydroxide particles; Dehydrating and modifying the pretreated aluminum hydroxide particles to obtain modified aluminum hydroxide particles; The modified aluminum hydroxide particles are ball-milled multiple times under a preset time interval to obtain n groups of ball-milled aluminum hydroxide particles; wherein the number n of groups of ball-milled aluminum hydroxide particles satisfies: n=T / t+1, where T is the duration of the multiple ball milling groupings, h; t is the preset interval length, h; n≥4 and n is an integer; performing a second freeze-drying on the ball-milled aluminum hydroxide particles to obtain n groups of frozen aluminum hydroxide particles; hydrolyzing n groups of the frozen aluminum hydroxide particles in sequence according to the ball milling time of the frozen aluminum hydroxide particles to obtain hydrolyzed materials; Filtering the hydrolyzed material to obtain a filter cake; The filter cake is dried and calcined in sequence to obtain a plate-shaped corundum powder product.

2. The method according to claim 1, characterized in that The modified aluminum hydroxide particles are subjected to ball milling for multiple times under a preset time interval to obtain multiple groups of ball milled aluminum hydroxide particles, comprising the steps of: Under the conditions of a first preset feeding amount and a preset interval time, the modified aluminum hydroxide particles are subjected to a second ball milling to obtain a first group of ball-milled aluminum hydroxide particles; Under the conditions of a second preset feeding amount and the preset interval time, a portion of the first group of ball-milled materials is subjected to a third ball milling to obtain a second group of ball-milled aluminum hydroxide particles; Under the conditions of the third preset feeding amount and the preset interval time, a portion of the second group of ball-milled materials is subjected to a fourth ball milling to obtain a third group of ball-milled aluminum hydroxide particles; …… Under the conditions of the nth preset feeding amount and the preset interval time, a portion of the n-1th group of ball-milled materials is subjected to the n+1th ball milling to obtain the nth group of ball-milled aluminum hydroxide particles; The first group of ball-milled aluminum hydroxide particles, the second group of ball-milled aluminum hydroxide particles, the third group of ball-milled aluminum hydroxide particles, ... and the nth group of ball-milled aluminum hydroxide particles are collected to obtain multiple groups of ball-milled aluminum hydroxide particles.

3. The method according to claim 2, characterized in that The first preset feeding amount is 10% to 30% of the total mass of the ball-milled aluminum hydroxide particles; and / or The second preset feeding amount is 10% to 30% of the total mass of the ball-milled aluminum hydroxide particles; and / or The third preset feeding amount is 10% to 30% of the total mass of the ball-milled aluminum hydroxide particles; and / or …… The nth preset feeding amount is 10% to 30% of the total mass of the ball-milled aluminum hydroxide particles.

4. The method according to claim 1 or 2, characterized in that The preset interval duration is 2 hours to 4 hours; and / or The duration of the ball milling grouping is 12 hours to 24 hours.

5. The method according to claim 1, wherein The frozen aluminum hydroxide particles include a first group of frozen aluminum hydroxide particles, a second group of frozen aluminum hydroxide particles, a third group of frozen aluminum hydroxide particles, ... and the nth group of frozen aluminum hydroxide particles; The method comprises the following steps: hydrolyzing n groups of the frozen aluminum hydroxide particles in sequence according to the ball milling time of the frozen aluminum hydroxide particles to obtain a hydrolyzed material. performing a first hydrolysis on the first group of frozen aluminum hydroxide particles to obtain a first group of hydrolyzed materials; adding the second group of frozen aluminum hydroxide particles to the first group of hydrolysis materials for a second hydrolysis to obtain a second group of hydrolysis materials; adding the third group of frozen aluminum hydroxide particles to the second group of hydrolysis materials to perform the second hydrolysis to obtain a third group of hydrolysis materials; …… The nth group of frozen aluminum hydroxide particles is added to the n-1th group of hydrolysis material to perform the second hydrolysis to obtain a hydrolysis material.

6. The method according to claim 5, characterized in that The duration of the first hydrolysis is twice the duration of the second hydrolysis.

7. The method according to claim 1, characterized in that The preset particle size is 5 μm to 20 μm.

8. The method according to claim 1, characterized in that The first ball milling time is 2 hours to 24 hours; and / or The first freeze-drying time is 2.0h to 2.5h; and / or The second freeze-drying time is 2.0h to 2.5h; and / or The temperature of the dehydration modification is 950° C. to 1100° C., and the time of the dehydration modification is 0.1s to 2.0s.

9. The method according to claim 1, characterized in that The filter cake is dried and calcined in sequence to obtain a plate-shaped corundum powder product, comprising the steps of: drying the filter cake to obtain raw meal; calcining the raw material powder to obtain an alumina calcined material; The alumina calcined material is subjected to a second calcination to obtain plate-like alumina powder.

10. The method according to claim 9, characterized in that The drying temperature is 90°C to 120°C; and / or The temperature of the first calcination is 980° C. to 1020° C., and the time of the first calcination is 2 h to 3 h; and / or The temperature of the second calcination is 1900° C. to 1940° C., and the time of the first calcination is 2 hours to 3 hours.

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