Production method of alumina for 5G ceramics, alumina for 5G ceramics

Abstract

The present application relates to a method for producing alumina specifically for 5G ceramics, which comprises the following steps: providing aluminum hydroxide having a sodium oxide content not higher than 0.3%, grinding and screening the aluminum hydroxide to obtain aluminum hydroxide particles having a predetermined particle size; mixing the aluminum hydroxide particles with a mineralizer to obtain a mixture, and calcining the mixture to obtain the 5G alumina specifically for ceramics, wherein the calcination comprises the following steps: heating the mixture to 140-160°C at a first heating rate and keeping it warm for 50-70 minutes; heating the mixture to 390-410°C at a second heating rate and keeping it warm for 50-70 minutes; heating the mixture to 790-810°C at a third heating rate and keeping it warm for 50-70 minutes; heating the mixture to 1120-1140°C at a heating rate of 20-30°C / h and keeping it warm for 7.5-8.5 hours. The present application can obtain 5G ceramic-specific alumina with low impurity element content, low original grain size and high specific surface area.

Description

Technical Field

[0001] The present invention relates to the field of aluminum industry, and in particular to alumina. Background Art

[0002] 5G communication technology access components must meet three fundamental performance requirements: full-spectrum access, high-frequency transmission (even millimeter-wave transmission), and ultra-high-bandwidth transmission. The materials used to manufacture them must possess characteristics such as large-scale integration, high frequency, and high spectral efficiency. Ceramic materials not only meet these requirements but also offer no signal shielding, high hardness, a strong visual effect, and excellent heat dissipation similar to that of metal. This makes 5G ceramics a promising emerging industry.

[0003] Calcined alpha alumina products, as raw materials for industrial ceramics, are widely used in wear-resistant ceramics, ceramic glazes, refractories, polishing, electronic ceramics, glass substrates, and other industries. As the variety of industrial ceramics expands, the market is placing higher demands on the quality of calcined alpha alumina. 5G ceramics impose stricter requirements on the impurity content, grain size, and specific surface area of ​​alpha alumina raw materials. Currently available calcined alpha alumina products are unable to meet the requirements of 5G ceramics. Alumina specifically for 5G ceramics has long been subject to import restrictions, and production technology has remained elusive. Summary of the Invention

[0004] The embodiments of the present application provide a method for producing alumina specifically for 5G ceramics to solve the technical problem that existing calcined α-alumina varieties cannot meet the requirements of 5G ceramics.

[0005] In a first aspect, an embodiment of the present application provides a method for producing alumina for 5G ceramics, the method comprising the following steps:

[0006] providing aluminum hydroxide having a sodium oxide content of no more than 0.3%, grinding and sieving the aluminum hydroxide to obtain aluminum hydroxide particles having a predetermined particle size;

[0007] The aluminum hydroxide particles are mixed with a mineralizer to obtain a mixture, and the mixture is calcined to obtain the 5G ceramic special alumina.

[0008] Wherein, the calcination comprises the following steps:

[0009] Heating the mixture to 140-160° C. at a first heating rate and keeping the temperature for 50-70 minutes;

[0010] heating the mixture to 390-410° C. at a second heating rate and keeping the temperature for 50-70 minutes;

[0011] heating the mixture to 790-810° C. at a third heating rate and keeping the temperature for 50-70 minutes;

[0012] The mixed material is heated to 1120-1140° C. at a heating rate of 20-30° C. / h and kept warm for 7.5-8.5 hours.

[0013] In some embodiments of the present application, the first heating rate is 40-50° C. / h.

[0014] In some embodiments of the present application, the second heating rate is 50-60° C. / h.

[0015] In some embodiments of the present application, the third heating rate is 40-50° C. / h.

[0016] In some embodiments of the present application, the predetermined particle size is 3-5 μm.

[0017] In some embodiments of the present application, the calcination is performed in a static kiln.

[0018] In some embodiments of the present application, the calcination is performed in a shuttle kiln.

[0019] In some embodiments of the present application, in the uniform mixing of the aluminum hydroxide particles and the mineralizer, the mass of the mineralizer accounts for 0.8%-1.2% of the mass of the aluminum hydroxide.

[0020] In a second aspect, an embodiment of the present application provides a 5G ceramic-specific alumina, which is prepared by the preparation method of the 5G ceramic-specific alumina described in any embodiment of the first aspect.

[0021] In some embodiments of the present application, the 5G ceramic-specific alumina is composed of the following components, calculated by mass ratio:

[0022] Sodium oxide 0.1%-0.3%

[0023] Silicon dioxide 0.03%-0.1%

[0024] Iron oxide 0.008%-0.02%

[0025] The balance is alumina.

[0026] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0027] The production method of 5G ceramic-specific alumina provided in the embodiment of the present application selects aluminum hydroxide with a low sodium oxide content as a raw material, so that the sodium content of the obtained 5G ceramic-specific alumina is very low; aluminum hydroxide particles with a predetermined particle size are used as raw materials, and the temperature change during the calcination process is controlled at the same time, so that 5G ceramic-specific alumina with a low impurity element content, a low original grain size and a high specific surface area can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] 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.

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces 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.

[0030] Figure 1 A schematic flow chart of a method for producing alumina for 5G ceramics provided in an embodiment of the present application. DETAILED DESCRIPTION

[0031] 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.

[0032] Unless otherwise specified, the terms used herein should be understood as having the same meaning as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. In the event of any conflict, the present specification shall take precedence.

[0033] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0034] Existing calcined α-alumina varieties have technical problems that cannot meet the needs of 5G ceramics.

[0035] The technical solutions provided in the embodiments of this application are intended to solve the above technical problems, and the overall idea is as follows:

[0036] In a first aspect, an embodiment of the present application provides a method for producing alumina for 5G ceramics, the method comprising the following steps:

[0037] S1: providing aluminum hydroxide having a sodium oxide content of not more than 0.3%, grinding and sieving the aluminum hydroxide to obtain aluminum hydroxide particles having a predetermined particle size;

[0038] S2: mixing the aluminum hydroxide particles with a mineralizer to obtain a mixture, and calcining the mixture to obtain the 5G ceramic-specific alumina.

[0039] Wherein, the calcination comprises the following steps:

[0040] Heating the mixture to 140-160° C. at a first heating rate and keeping the temperature for 50-70 minutes;

[0041] heating the mixture to 390-410° C. at a second heating rate and keeping the temperature for 50-70 minutes;

[0042] heating the mixture to 790-810° C. at a third heating rate and keeping the temperature for 50-70 minutes;

[0043] The mixed material is heated to 1120-1140° C. at a heating rate of 20-30° C. / h and kept warm for 7.5-8.5 hours.

[0044] The present application first grinds and sieves aluminum hydroxide before calcination to obtain aluminum hydroxide particles with a predetermined particle size. The aluminum hydroxide particles are used as calcination raw materials, which makes it easier to control the particle size of the obtained 5G ceramic-specific alumina.

[0045] The present application controls the temperature change during the calcination process, thereby achieving the technical effect of reducing the particle size and particle size variance of 5G ceramic-specific alumina.

[0046] The mineralizer described in this application is used to reduce the calcination temperature, remove some sodium oxide, and control the uniform growth of the original crystal size. The mineralizer can be, for example, boric acid or magnesium oxide.

[0047] The beneficial effect of heating the mixture to 1120-1140° C. at a heating rate of 20-30° C. / h is that the slow formation of α-alumina particles is controlled at a lower heating rate, which is beneficial to reducing the original grain size of the 5G ceramic special alumina.

[0048] This application selects aluminum hydroxide with low sodium oxide content as raw material, so that the sodium content of the obtained 5G ceramic-specific alumina is very low; using aluminum hydroxide particles with a predetermined particle size as raw material, and controlling the temperature change during the calcination process, it is finally possible to obtain 5G ceramic-specific alumina with low impurity element content, low original grain size and high specific surface area.

[0049] In some embodiments of the present application, the first heating rate is 40-50° C. / h.

[0050] The first heating rate is controlled within the above range, which neither causes uneven formation of aluminum oxide particles due to excessively rapid heating, nor affects production efficiency due to excessively slow heating.

[0051] In some embodiments of the present application, the second heating rate is 50-60° C. / h.

[0052] The second heating rate is controlled within the above range, which neither causes uneven formation of aluminum oxide particles due to excessively rapid heating, nor affects production efficiency due to excessively slow heating.

[0053] In some embodiments of the present application, the third heating rate is 40-50° C. / h.

[0054] The third heating rate is controlled within the above range, which neither causes uneven formation of aluminum oxide particles due to excessively rapid heating, nor affects production efficiency due to excessively slow heating.

[0055] In some embodiments of the present application, the predetermined particle size is 3-5 μm.

[0056] The beneficial effect of selecting the predetermined particle size within the above range is that the use requirements can be met without the need for secondary crushing after calcination, while ensuring that the particles of the primary crushing are relatively uniform to reduce the impact of calcination.

[0057] In some embodiments of the present application, the calcination is performed in a static kiln.

[0058] The beneficial effect of calcining in a static kiln is that the original grain size grows more uniformly, and the material rushing phenomenon caused by material flow is reduced to reduce the product quality.

[0059] In some embodiments of the present application, the calcination is performed in a shuttle kiln.

[0060] The beneficial effects of calcining in a shuttle kiln are that the temperature field is more uniform, the calcining temperature insulation effect is good, the phase change is more complete, and the original grain size is better uniform.

[0061] In some embodiments of the present application, in the uniform mixing of the aluminum hydroxide particles and the mineralizer, the mass of the mineralizer accounts for 0.8%-1.2% of the mass of the aluminum hydroxide.

[0062] The beneficial effect of selecting the amount of the mineralizer within the above range is that it can effectively adjust the size of the alumina grains in the 5G ceramic-specific alumina obtained by subsequent calcination without affecting the morphology of the alumina main phase.

[0063] In a second aspect, an embodiment of the present application provides a 5G ceramic-specific alumina, which is prepared by the preparation method of the 5G ceramic-specific alumina described in any embodiment of the first aspect.

[0064] In some embodiments of the present application, the 5G ceramic-specific alumina is composed of the following components, calculated by mass ratio:

[0065] Sodium oxide 0.1%-0.3%

[0066] Silicon dioxide 0.03%-0.1%

[0067] Iron oxide 0.008%-0.02%

[0068] The balance is alumina.

[0069] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are generally measured in accordance with national standards. If there are no corresponding national standards, then the methods are carried out in accordance with general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0070] Example

[0071] This embodiment provides a method for producing alumina specifically for 5G ceramics, the method comprising the following steps:

[0072] Sa: providing aluminum hydroxide having a sodium oxide content of 0.24%, grinding and sieving the aluminum hydroxide to obtain aluminum hydroxide particles having a particle size of 3-5 μm;

[0073] Sb: The aluminum hydroxide particles are mixed with a mineralizer to obtain a mixture, and the mixture is calcined in a shuttle kiln to obtain the 5G ceramic special alumina.

[0074] Wherein, the calcination comprises the following steps:

[0075] Sb1: heating the mixture to 150°C at a heating rate of 50°C / h and keeping the temperature for 60 minutes;

[0076] Sb2: Heat the mixture to 400°C at a heating rate of 50°C / h and keep it at that temperature for 60 minutes;

[0077] Sb3: Heat the mixture to 800°C at a heating rate of 50°C / h and keep it at that temperature for 60 minutes;

[0078] Sb4: The mixture was heated to 1130°C at a heating rate of 25°C / h and kept at this temperature for 8 hours.

[0079] In the uniform mixing of the aluminum hydroxide particles and the mineralizer, the mass of the mineralizer accounts for 1% of the mass of the aluminum hydroxide.

[0080] After testing, the 5G ceramic special alumina obtained by the above method consists of the following components:

[0081] Sodium oxide 0.3%

[0082] Silicon dioxide 0.07%

[0083] Iron oxide 0.011%

[0084] The balance is alumina.

[0085] Comparative Example 1

[0086] The difference between this comparative example and Example 1 is only that:

[0087] In step Sa, grinding and screening are not performed.

[0088] In step Sb, calcination is directly started with unground and unscreened aluminum hydroxide as raw material.

[0089] After testing, the aluminum oxide obtained by the above method consists of the following components:

[0090] Sodium oxide 0.33%

[0091] Silicon dioxide 0.07%

[0092] Iron oxide 0.01%

[0093] The balance is alumina.

[0094] Comparative Example 2

[0095] The difference between this comparative example and Example 1 is only that:

[0096] Steps Sb1 to Sb3 are not subjected to heat preservation.

[0097] After testing, the aluminum oxide obtained by the above method consists of the following components:

[0098] Sodium oxide 0.3%

[0099] Silicon dioxide 0.07%

[0100] Iron oxide 0.009%

[0101] The balance is alumina.

[0102] Related experiments and effect data:

[0103] The original grain size and specific surface area of ​​the aluminum oxide obtained in Example, Comparative Example 1 and Comparative Example 2 were tested. The test results are shown in Table 1.

[0104] Original grain size (unit: μm) Specific surface area (unit: m2 / g) Example 1.0 15.5 Comparative Example 1 1.5 8.6 Comparative Example 2 Incomplete phase conversion 56.4

[0105] As can be seen from Table 1, in terms of the requirements for 5G ceramic-specific alumina, the original grain size and specific surface area data of Comparative Examples 1 and 2 are inferior to those of the Examples. This shows that the Examples, by adopting the technical means of pre-grinding and screening the aluminum hydroxide and staged heating, can better control the above-mentioned indicators of the obtained alumina.

[0106] 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 hard 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 numbers within the range. For example, the description of a range 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 applies 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.

[0107] In this application, unless otherwise indicated, directional terms such as "upper" and "lower" refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of this application specification, the terms "include", "comprise", etc. mean "including but not limited to". Moreover, the terms "include", "comprises", or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article, or device. In the absence of further restrictions, the elements defined by the phrase "include..." do not exclude the presence of other identical elements in the process, method, article, or device comprising the elements. In this document, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another, and do not necessarily require or imply any actual relationship or order between these entities or operations. In this document, "and / or" describes the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, or B exists alone. For the association relationship of more than three associated objects described with "and / or", it means that any one of these three associated objects can exist alone, or any at least two of them exist at the same time. For example, for A, and / or B, and / or C, it can be represented that any one of A, B, and C exists alone, or any two of them exist at the same time, or three of them exist at the same time. In this article, "at least one" refers to one or more, and "multiple" refers to two or more. "At least one", "the following at least one (individual)" or similar expressions refer to any combination of these items, including any combination of single item (individual) or plural items (individual). For example, "at least one (individual) of a, b, or c", or "at least one (individual) of a, b, and c", can all represent: a, b, c, ab (i.e., a and b), ac, bc or abc, where a, b, c can be single or multiple, respectively.

[0108] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. 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 application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for producing alumina for 5G ceramics, characterized in that: The production method of the 5G ceramic special aluminum oxide comprises the following steps: providing aluminum hydroxide having a sodium oxide content of no more than 0.3%, grinding and sieving the aluminum hydroxide to obtain aluminum hydroxide particles having a particle size of 3-5 μm; The aluminum hydroxide particles are mixed with a mineralizer to obtain a mixture, and the mixture is calcined to obtain the 5G ceramic special alumina. Wherein, the calcination comprises the following steps: Heating the mixture to 140-160°C at a heating rate of 40-50°C / h and keeping the temperature for 50-70 minutes; Heating the mixture to 390-410°C at a heating rate of 50-60°C / h and keeping the temperature for 50-70 minutes; Heating the mixture to 790-810°C at a heating rate of 40-50°C / h and keeping the temperature for 50-70 minutes; Heating the mixture to 1120-1140°C at a heating rate of 20-30°C / h and keeping the temperature for 7.5-8.5h; Calculated by mass ratio of the 5G ceramic special alumina, the 5G ceramic special alumina consists of the following components: Sodium oxide 0.1%-0.3% Silicon dioxide 0.03%-0.1% Iron oxide 0.008%-0.02% The balance is aluminum oxide; The aluminum hydroxide particles are uniformly mixed with a mineralizer, wherein the mass of the mineralizer accounts for 0.8%-1.2% of the mass of the aluminum hydroxide, and the mineralizer is selected from one of boric acid and magnesium oxide.

2. The method for producing 5G ceramic special alumina according to claim 1, characterized in that: The calcination is carried out in a static kiln.

3. The method for producing 5G ceramic special alumina according to claim 1, characterized in that: The calcination is carried out in a shuttle kiln.

4. A 5G ceramic special alumina, characterized in that: The 5G ceramic-specific alumina is prepared by the preparation method of the 5G ceramic-specific alumina according to any one of claims 1 to 3.

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