Preparation method of high-purity nano aluminum oxide and high-purity nano aluminum oxide

Abstract

The invention provides a preparation method of high-purity nanometer aluminum oxide and the high-purity nanometer aluminum oxide, and belongs to the field of aluminum oxide powder materials. Comprising the following steps: sequentially carrying out first roasting and first crushing on high-purity aluminum hydroxide to obtain gamma-Al2O3; sequentially carrying out second roasting and second crushing on the gamma-Al2O3, so as to obtain alpha-Al2O3; the preparation method comprises the following steps: preparing alpha-Al2O3 into first slurry, adding a dispersing agent into the first slurry, and carrying out wet grinding on the first slurry containing the dispersing agent to obtain second slurry; sequentially filtering and washing the second slurry to obtain a filter cake; pulping the filter cake to obtain third slurry; and carrying out spray drying on the third slurry to obtain the high-purity nano aluminum oxide powder. According to the method, the aluminum hydroxide precursor is ensured to be converted into gamma-Al2O3 and gamma-Al2O3 is ensured to be converted into alpha-Al2O3 through multi-section roasting, and meanwhile, the aim of controlling the particle size distribution of the product is achieved through crushing after roasting.

Description

Technical Field

[0001] The present application relates to the technical field of alumina powder materials, and in particular to a preparation method of high-purity nano alumina and high-purity nano alumina. Background Art

[0002] High-purity nano-alumina powder is not only of high purity, but also has a particle size of nanometers, a narrow particle size distribution, and good dispersibility. The small size effect, surface interface effect, quantum size effect, and macroscopic quantum tunneling effect of nano-powders make them have broad application prospects in the fields of catalysis, light filtering, light absorption, medicine, magnetic media, and new materials. High-purity nano-alumina has excellent optical, electrical, and mechanical properties and is widely used in the field of modern high-tech new materials.

[0003] There are many kinds of precursors for high-purity nano-alumina, and the physical properties of nano-alumina produced by different precursors are not the same, and each has its own advantages and disadvantages. However, the existing high-purity alumina powder has the problem of uneven particle size distribution during the preparation process, which seriously affects the application of high-purity alumina powder. Summary of the invention

[0004] The present application provides a preparation method of high-purity nano-alumina and high-purity nano-alumina to solve the technical problem of uneven particle size distribution in the preparation process of existing high-purity alumina powder.

[0005] In a first aspect, the present application provides a method for preparing high-purity nano-alumina, the method comprising:

[0006] The high-purity aluminum hydroxide is subjected to a first roasting and a first pulverization in sequence to obtain γ-Al2O3;

[0007] The γ-Al2O3 is subjected to a second calcination and a second pulverization in sequence to obtain α-Al2O3;

[0008] The α-Al2O3 is configured into a first slurry, and a dispersant is added to the first slurry, and then the first slurry containing the dispersant is wet-grinded to obtain a second slurry;

[0009] filtering and washing the second slurry in sequence to obtain a filter cake;

[0010] Slurrying the filter cake to obtain a third slurry; and

[0011] The third slurry is spray-dried to obtain high-purity nano-alumina powder.

[0012] Optionally, the temperature of the first calcination is 600° C.-1000° C., and the insulation time of the first calcination is 60 min-180 min.

[0013] Optionally, the first crushing is air flow crushing, and the second crushing is a combination of pre-crushing and air flow crushing or pre-crushing, and the pre-crushing is crushing using a double-roll device.

[0014] Optionally, the crushing pressure of the air flow milling is 0.4MPa-0.7MPa, and the feed rate of the air flow milling is 1kg / min-3kg / min.

[0015] Optionally, the temperature of the second calcination is 1100° C.-1400° C., and the insulation time of the second calcination is 60 min-180 min.

[0016] Optionally, the added amount of the dispersant is 0.1%-1% of the mass of the first slurry.

[0017] Optionally, the solid content of the first slurry and the third slurry is 10%-30%.

[0018] Optionally, the spray drying temperature is 220°C-250°C.

[0019] In a second aspect, the present application provides a high-purity nano-alumina prepared by the method described in any one of the embodiments of the first aspect, wherein the high-purity nano-alumina is used in the field of ceramic substrates and polishing.

[0020] Optionally, the high-purity nano-alumina satisfies at least one of the following properties: purity ≥ 99.9% and grain size of 30nm-500nm.

[0021] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0022] The present application provides a method for preparing high-purity nano-alumina, comprising: performing a first roasting and a first crushing on high-purity aluminum hydroxide in sequence to obtain γ-Al2O3; performing a second roasting and a second crushing on γ-Al2O3 in sequence to obtain α-Al2O3; configuring α-Al2O3 into a first slurry, adding a dispersant to the first slurry, and then wet-grinding the first slurry containing the dispersant to obtain a second slurry; filtering and washing the second slurry in sequence to obtain a filter cake; beating the filter cake to obtain a third slurry; and spray-drying the third slurry to obtain a high-purity nano-alumina powder. Through multi-stage roasting, it is ensured that the aluminum hydroxide precursor is converted into γ-Al2O3 and γ-Al2O3 is converted into α-Al2O3. At the same time, through the crushing after roasting, the purpose of controlling the particle size distribution of the product is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] 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.

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0025] Figure 1 A schematic flow chart of a method for preparing high-purity nano-alumina provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0027] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0028] In addition, in the description of the specification of the present application, the terms "including", "comprising", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second", etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" means one or more, and "plurality" means two or more. "At least one", "the following at least one item (items)" or similar expressions refer to any combination of these items, including any combination of single items (items) or plural items (items). For example, "at least one of a, b, or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e. a and b), ac, bc or abc, where a, b, c can be single or plural, respectively.

[0029] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0030] Figure 1 A schematic flow chart of a method for preparing high-purity nano-alumina provided in an embodiment of the present application.

[0031] See also Figure 1 The present application provides a method for preparing high-purity nano-alumina, the method comprising:

[0032] S1, performing a first roasting and a first crushing in sequence on high-purity aluminum hydroxide to obtain γ-Al2O3;

[0033] In some embodiments, the purity of the high-purity aluminum hydroxide is ≥99.9%.

[0034] In some embodiments, the temperature of the first calcination is 600° C.-1000° C., and the holding time of the first calcination is 60 min-180 min.

[0035] In the above embodiment, the temperature and time of the first calcination are controlled to ensure that the high-purity aluminum hydroxide is completely converted into γ-Al2O3. If the calcination temperature is lower than 600°C or the holding time is lower than 60min, the aluminum hydroxide conversion will be incomplete and there will be some amorphous aluminum hydroxide; if the calcination temperature is higher than 1000°C or the calcination time is higher than 180min, part of the γ-Al2O3 will be converted into α-Al2O3, which is not conducive to controlling the product particle size distribution and affecting the final performance. Exemplarily, the temperature of the first calcination can be 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, etc., and the holding time of the first calcination can be 60min, 70min, 90min, 100min, 120min, 140min, 160min, 180min, etc.

[0036] S2, sequentially performing a second calcination and a second pulverization on the γ-Al2O3 to obtain α-Al2O3;

[0037] In some embodiments, the first pulverization is air flow pulverization, and the second pulverization is a combination of pre-crushing and air flow pulverization or pre-crushing, and the pre-crushing is performed using a double-roll device.

[0038] In the above embodiment, the process and process parameters of the first pulverization and the second pulverization can be controlled according to the product particle size requirements of the high-purity nano-alumina powder.

[0039] In some embodiments, the crushing pressure of the air flow milling is 0.4 MPa-0.7 MPa, and the feed rate of the air flow milling is 1 kg / min-3 kg / min.

[0040] In the above embodiment, the crushing pressure and feed rate of the airflow crushing are controlled to ensure the crushing efficiency of the material. If the crushing pressure is lower than 0.4MPa, the crushing efficiency will be reduced, resulting in some agglomerates being unable to be completely opened. If the crushing pressure is higher than 0.7MPa, the material will be unable to press the crushing airflow, resulting in backblowing and material loss. Exemplarily, the crushing pressure of the airflow crushing can be 0.4MPa, 0.45MPa, 0.5MPa, 0.55MPa, 0.6MPa, 0.65MPa, 0.7MPa, etc., and the feed rate of the airflow crushing can be 1kg / min, 1.2kg / min, 1.5kg / min, 1.8kg / min, 2kg / min, 2.5kg / min, 3kg / min, etc.

[0041] In some embodiments, the temperature of the second calcination is 1100° C.-1400° C., and the holding time of the second calcination is 60 min-180 min.

[0042] In the above embodiment, the temperature and time of the second calcination are controlled to ensure the conversion rate of γ-Al2O3 to α-Al2O3. If the calcination temperature is lower than 1100°C or the holding time is lower than 60min, the conversion rate is too low, affecting the performance of subsequent products; if the calcination temperature is higher than 1400°C or the holding time is higher than 180min, the conversion efficiency is too high, resulting in excessively large original crystals of α-Al2O3 and easy adhesion between original crystals, which is not conducive to subsequent wet grinding and uneven particle size distribution. Exemplarily, the temperature of the second calcination can be 1100°C, 1150°C, 1200°C, 1250°C, 1300°C, 1350°C, 1400°C, etc., and the holding time of the second calcination can be 60min, 70min, 90min, 100min, 120min, 140min, 160min, 180min, etc.

[0043] S3, preparing α-Al2O3 into a first slurry, adding a dispersant to the first slurry, and then wet-grinding the first slurry containing the dispersant to obtain a second slurry;

[0044] In some embodiments, the dispersant is an organic polymer dispersant, and the organic polymer dispersant includes BYK series dispersants.

[0045] BYK series dispersants include: BYK-AT203, BYK-AT204, BYK-9076, BYK-180, BYK-170, BYK-101, BYK-102, BYK-110.

[0046] In some embodiments, configuring α-Al 2 O 3 into the first slurry specifically comprises: mixing α-Al 2 O 3 with water to configure the first slurry.

[0047] In some embodiments, the solid content of the first slurry is 10%-30%.

[0048] In the above embodiment, the solid content of the first slurry is controlled to improve the grinding efficiency of wet grinding. If the solid content is less than 10%, the wet grinding efficiency is affected, the loss of grinding beads is increased, and the product is polluted; if the solid content is higher than 30%, the material is too thick, the fluidity is too poor, and the grinding uniformity is affected. Exemplarily, the solid content of the first slurry can be 10%, 12%, 15%, 20%, 22%, 25%, 28%, 30%, etc.

[0049] In some embodiments, the amount of the dispersant added is 0.1%-1% of the mass of the first slurry.

[0050] In the above embodiment, controlling the amount of dispersant added helps to improve grinding efficiency, reduce the risk of grinding blockage, reduce water consumption and increase the solid content of the slurry. If the amount of dispersant added is higher than 1%, the dispersion effect is no longer significantly increased and the material is polluted. If the amount of dispersant added is lower than 0.1%, the dispersion effect is poor and the fluidity of the solution is poor. Exemplarily, the amount of dispersant added can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.8%, 1%, etc. of the mass of the first slurry.

[0051] S4, filtering and washing the second slurry in sequence to obtain a filter cake;

[0052] S5, beating the filter cake to obtain a third slurry; and

[0053] It should be noted that beating is a purification process that utilizes the fact that substances have poor solubility in solvents, but impurities have good solubility in solvents. By beating, the purity of alumina can be further improved.

[0054] In some embodiments, the solid content of the third slurry is 10%-30%.

[0055] In the above embodiment, the solid content of the third slurry is controlled to improve the efficiency of spray drying. For example, the solid content of the third slurry can be 10%, 12%, 15%, 20%, 22%, 25%, 28%, 30%, etc.

[0056] S6. Spray-drying the third slurry to obtain high-purity nano-alumina powder.

[0057] In some embodiments, the spray drying temperature is 220°C-250°C.

[0058] In the above embodiment, the spray drying temperature is controlled to improve the efficiency of the spray drying. If the spray drying temperature is higher than 250°C, the equipment will be damaged and the service life of the equipment will be affected; if the spray drying temperature is lower than 220°C, the drying efficiency will be too low. Exemplarily, the spray drying temperature can be 220°C, 225°C, 230°C, 235°C, 240°C, 245°C, 250°C, etc.

[0059] Based on a general inventive concept, the present application provides a high-purity nano-alumina prepared by the method described in any one of the embodiments of the first aspect, wherein the high-purity nano-alumina is used in the field of ceramic substrates and polishing.

[0060] In some embodiments, the high-purity nano-alumina satisfies at least one of the following properties: purity ≥ 99.9% and grain size of 30nm-500nm.

[0061] The present application rationally designs the roasting, crushing and drying process for preparing high-purity nano-alumina. Through multi-stage roasting, it is ensured that the aluminum hydroxide precursor is converted into γ-Al2O3 and γ-Al2O3 is converted into α-Al2O3. At the same time, through the crushing process after roasting, the purpose of controlling the particle size distribution of the product is achieved.

[0062] The high-purity nano-alumina is realized based on the preparation method of the high-purity nano-alumina mentioned above. The specific steps of the preparation method of the high-purity nano-alumina can refer to the above embodiment. Since the high-purity nano-alumina adopts part or all of the technical solutions of the above embodiment, it has at least all the beneficial effects brought by the technical solutions of the above embodiment, which will not be repeated here one by one.

[0063] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to industry standards. If there is no corresponding industry standard, then the conditions recommended by the manufacturer are followed.

[0064] This embodiment provides a method for preparing high-purity nano-alumina, the method comprising:

[0065] S1. Performing first roasting and airflow crushing on high-purity aluminum hydroxide in sequence to obtain γ-Al2O3; wherein the first roasting temperature is 600°C-1000°C, the first roasting holding time is 60min-180min, the crushing pressure of airflow crushing is 0.4MPa-0.7MPa, and the feeding rate is 1kg / min-3kg / min;

[0066] S2, sequentially performing a second roasting on the γ-Al2O3 and crushing it using a roller device to obtain α-Al2O3; wherein the second roasting temperature is 1100° C.-1400° C., and the second roasting holding time is 60 min-180 min;

[0067] S3, preparing α-Al2O3 into a first slurry, adding a dispersant to the first slurry, and then wet-grinding the first slurry containing the dispersant to obtain a second slurry; wherein the dispersant is BYK-AT204, the amount of the dispersant added is 0.1%-1% of the mass of the first slurry, and the solid content of the first slurry is 10%-30%;

[0068] S4, filtering and washing the second slurry in sequence to obtain a filter cake; wherein the amount of water used for washing is 3 times that of the slurry, and the temperature of the washing water is 80°C;

[0069] S5, beating the filter cake to obtain a third slurry; wherein the solid content of the third slurry is 10%-30%;

[0070] S6. Spray-drying the third slurry to obtain high-purity nano-alumina powder; wherein the spray-drying temperature is 220° C.-250° C., and the process parameters of the preparation method of high-purity nano-alumina are shown in Table 1.

[0071] Table 1 Process parameters of the preparation method of high-purity nano-alumina

[0072]

[0073]

[0074] The high-purity nano-alumina powder obtained in the embodiment and the comparative example was tested for impurity content, purity and particle size distribution. The results are shown in Table 2.

[0075] Table 2 Physical and chemical indicators of high-purity nano-alumina powder obtained in the examples and comparative examples

[0076]

[0077]

[0078] In addition, one or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0079] In the embodiment of the present invention, the method for preparing high-purity alumina powder provides a product with high purity, uniform and controllable grain size distribution, and good product grain dispersibility. The purity of the obtained high-purity nano alumina is above 99.9%, and the grain size is controllable from 30nm to 500nm.

[0080] In the embodiments of the present invention, the provided process and product can better control the grain size and have greater advantages in the fields of ceramic substrates and polishing.

[0081] In the embodiments of the present invention, the obtained high-purity nano-alumina has obvious advantages over the common alumina calcination method in that the calcination temperature is low and the product has good microscopic morphology.

[0082] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for preparing high-purity nano-alumina, characterized in that: The method comprises: The high-purity aluminum hydroxide is subjected to a first roasting and a first pulverization in sequence to obtain γ-Al2O3; The γ-Al2O3 is subjected to a second calcination and a second pulverization in sequence to obtain α-Al2O3; The α-Al2O3 is configured into a first slurry, and a dispersant is added to the first slurry, and then the first slurry containing the dispersant is wet-grinded to obtain a second slurry; filtering and washing the second slurry in sequence to obtain a filter cake; Slurrying the filter cake to obtain a third slurry; and The third slurry is spray-dried to obtain high-purity nano-alumina powder.

2. The method according to claim 1, characterized in that: The temperature of the first calcination is 600° C.-1000° C., and the insulation time of the first calcination is 60 min-180 min.

3. The method according to claim 1, characterized in that The first pulverization is air flow pulverization, and the second pulverization is a combination of pre-crushing and air flow pulverization or pre-crushing, wherein the pre-crushing is performed using a double-roll device.

4. The method according to claim 3, characterized in that The crushing pressure of the air flow milling is 0.4MPa-0.7MPa, and the feeding speed of the air flow milling is 1kg / min-3kg / min.

5. The method according to claim 1, characterized in that The temperature of the second calcination is 1100° C.-1400° C., and the insulation time of the second calcination is 60 min-180 min.

6. The method according to claim 1, characterized in that The added amount of the dispersant is 0.1%-1% of the mass of the first slurry.

7. The method according to claim 1, characterized in that The solid contents of the first slurry and the third slurry are both 10%-30%.

8. The method according to claim 1, characterized in that The spray drying temperature is 220°C-250°C.

9. A high-purity nano-alumina prepared by the method according to any one of claims 1 to 8, characterized in that: The high-purity nano-alumina is used in the fields of ceramic substrates and polishing.

10. The high-purity nano-alumina according to claim 9, characterized in that: The high-purity nano-alumina meets at least one of the following properties: purity ≥ 99.9% and a grain size of 30nm-500nm.

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