Process for the preparation of a coarse particulate aluminum hydroxide

Abstract

The application relates to the technical field of aluminum hydroxide, in particular to a preparation method of coarse-grained aluminum hydroxide; the preparation method comprises the following steps: continuously decomposing sodium aluminate solution through carbonation to obtain coarse-grained aluminum hydroxide slurry; drying the coarse-grained aluminum hydroxide slurry, and then performing multi-stage continuous screening and multi-stage air separation to obtain high-quality coarse-grained aluminum hydroxide products; the continuous decomposition through carbonation comprises continuously decomposing in a gradient-decreasing manner of aluminum oxide concentration; the particle size of the coarse-grained aluminum hydroxide products meets the requirements of D10>=145 mu m, D50>=220 mu m and D90>=300 mu m; the existing sodium aluminate decomposition stage is introduced with continuous carbonation decomposition, the continuous decomposition process is controlled in a gradient-decreasing manner of aluminum oxide concentration, and then the particle size of the dried aluminum hydroxide is accurately graded through multi-stage continuous screening and multi-stage air separation, so that the high-quality coarse-grained aluminum hydroxide products with concentrated particle size distribution are obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aluminum hydroxide, in particular to a preparation method of coarse-grained aluminum hydroxide. BACKGROUND

[0002] Aluminum hydroxide is widely used as inorganic environmental protection type flame retardant filler due to its high whiteness, moderate refractive index, easy processing, good flame retardation, smoke suppression and other performances. Meanwhile, its composite also has unique translucent appearance, bright appearance, exquisite and delicate appearance and other advantages, and is widely used in artificial stone plate, jade handicraft and other industries. High-end aluminum hydroxide is also applied to the production of SMC, BMC and other new materials and to the automobile and high-speed rail industries.

[0003] In recent years, with the continuous progress and innovation of science and technology, high-quality coarse-grained aluminum hydroxide products are currently used as flame retardant fillers and for producing automobile airbag chips, which provides a broad market space for high-quality coarse-grained aluminum hydroxide. However, since the field involves the personal safety of drivers and passengers, the required aluminum hydroxide product must be 100% high quality to ensure the high reliability of the airbag chip. The high quality of aluminum hydroxide is reflected in its particle size distribution, so it is necessary to obtain aluminum hydroxide products with concentrated particle size distribution. However, the current preparation method generally obtains high-quality high-white aluminum hydroxide products with uniform particle size distribution. SUMMARY

[0004] The present application provides a preparation method of coarse-grained aluminum hydroxide to solve the problem that it is difficult to prepare high-quality high-white aluminum hydroxide products with concentrated particle size distribution in the prior art.

[0005] In a first aspect, the present application provides a preparation method of coarse-grained aluminum hydroxide, which comprises:

[0006] carbonating and continuously decomposing the sodium aluminate solution to obtain a coarse-grained aluminum hydroxide slurry;

[0007] drying the coarse-grained aluminum hydroxide slurry, and then performing multi-stage continuous screening and multi-stage air separation to obtain a high-quality coarse-grained aluminum hydroxide product;

[0008] The carbonating and continuous decomposition comprises continuously decomposing in a gradient descending manner of aluminum oxide concentration.

[0009] The particle size of the coarse-grained aluminum hydroxide product satisfies D10≥145 μm, D50≥220 μm and D90≥300 μm.

[0010] Optionally, the initial aluminum oxide concentration of the carbonating and continuous decomposition is 110 g / L-130 g / L, and the final aluminum oxide concentration of the carbonating and continuous decomposition is 10 g / L-12 g / L.

[0011] Optionally, the carbonation continuous decomposition comprises a first decomposition stage, a second decomposition stage, a third decomposition stage, a fourth decomposition stage and a fifth decomposition stage.

[0012] The aluminum oxide concentration of the first decomposition stage is 70g / L-80g / L, the aluminum oxide concentration of the second decomposition stage is 50g / L-60g / L, the aluminum oxide concentration of the third decomposition stage is 30g / L-40g / L, the aluminum oxide concentration of the fourth decomposition stage is 20g / L-30g / L, and the aluminum oxide concentration of the fifth decomposition stage is 10g / L-12g / L.

[0013] Optionally, the mesh size of the screen used in the multi-stage continuous screening is 30-70 mesh.

[0014] Optionally, the rotational speed of the screen used in the multi-stage continuous screening is 500r / min-900r / min.

[0015] Optionally, the multi-stage continuous screening comprises a first screening, a second screening, a third screening, a fourth screening and a fifth screening; the mesh size of the screens used in the first screening, the second screening, the third screening, the fourth screening and the fifth screening is distributed in an increasing order.

[0016] Optionally, the rotational speed of the screen used in the first screening is 800r / min-900r / min, the rotational speed of the screen used in the second screening is 650r / min-750r / min, the rotational speed of the screen used in the third screening is 600r / min-700r / min, the rotational speed of the screen used in the fourth screening is 550r / min-650r / min, and the rotational speed of the screen used in the fifth screening is 500r / min-600r / min.

[0017] Optionally, the damper opening of the multi-stage air separation is 20%-70%.

[0018] Optionally, the multi-stage air separation comprises a first air separation, a second air separation, a third air separation, a fourth air separation and a fifth air separation.

[0019] The damper opening of the first air separation is 60%-70%, the damper opening of the second air separation is 40%-45%, the damper opening of the third air separation is 35%-40%, the damper opening of the fourth air separation is 30%-35%, and the damper opening of the fifth air separation is 20%-30%.

[0020] Optionally, the particle size of aluminum hydroxide in the coarse-grained aluminum hydroxide slurry is 120μm-240μm, and the weight concentration of aluminum hydroxide in the coarse-grained aluminum hydroxide slurry is 45%-70%.

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

[0022] The preparation method of the coarse-grained aluminum hydroxide provided by the embodiments of the present application can make the particle size of the coarse-grained aluminum hydroxide slurry uniformly distributed within a certain alumina concentration range through multiple carbonation and decomposition processes, and then the particle size of the aluminum hydroxide can be further accurately graded through drying, multi-stage continuous screening and multi-stage air separation, so that a high-quality coarse-grained aluminum hydroxide product with concentrated particle size distribution can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present application and, together with the specification, serve to explain the principles of the application.

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows, and obviously, other drawings can also be obtained by those skilled in the art without creative labor.

[0025] Figure 1 The flowchart of the preparation method of the coarse-grained aluminum hydroxide provided by the embodiments of the present application is shown in the figure.

[0026] Figure 2 The industrial preparation flowchart of the preparation method of the coarse-grained aluminum hydroxide provided by the embodiments of the present application is shown in the figure.

[0027] Figure 3 The SEM diagram of the coarse-grained aluminum hydroxide product obtained by the preparation method provided by the comparative example 1 of the present application is shown in the figure.

[0028] Figure 4 The SEM diagram of the coarse-grained aluminum hydroxide product obtained by the preparation method provided by the embodiments of the present application is shown in the figure. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0030] Unless otherwise specifically indicated, all raw materials, reagents, instruments and equipment used in the present application can be purchased on the market or prepared by existing methods.

[0031] As shown in Figure 1 The present application provides a preparation method of coarse-grained aluminum hydroxide, which comprises the following steps:

[0032] S1. Carbonating and continuously decomposing a sodium aluminate solution to obtain a coarse-grained aluminum hydroxide slurry;

[0033] S2. Drying the coarse-grained aluminum hydroxide slurry, and then performing multi-stage continuous screening and multi-stage air separation to obtain a high-quality coarse-grained aluminum hydroxide product;

[0034] The carbonating and continuous decomposition comprises continuously decomposing in a manner that the aluminum oxide concentration decreases in a gradient manner.

[0035] The particle size of the coarse-grained aluminum hydroxide product satisfies D10≥145 μm, D50≥220 μm and D90≥300 μm.

[0036] In the present application, by limiting the specific particle size of the coarse-grained aluminum hydroxide product, it can be indicated that the product obtained by the preparation method is concentrated in the range of D10≥145 μm, D50≥220 μm and D90≥300 μm.

[0037] It should be noted that the multi-stage continuous screening can use a stainless steel screen.

[0038] The multi-stage air separation can use a DN150 stainless steel negative pressure air pipe valve to control the opening degree of the air door.

[0039] In some optional embodiments, the initial aluminum oxide concentration of the carbonating and continuous decomposition is 110 g / L-130 g / L, and the final aluminum oxide concentration of the carbonating and continuous decomposition is 10 g / L-12 g / L.

[0040] In the present application, by limiting the specific initial aluminum oxide concentration and the specific final aluminum oxide concentration of the carbonating and continuous decomposition, the particle size distribution of the coarse-grained aluminum hydroxide slurry can be clearly obtained, so that the high-quality coarse-grained aluminum hydroxide product with a particle size d50≥220 μm can be obtained subsequently.

[0041] The initial aluminum oxide concentration of the carbonating and continuous decomposition can be 110 g / L, 115 g / L, 120 g / L, 125 g / L or 130 g / L.

[0042] The final aluminum oxide concentration of the carbonation continuous decomposition can be 10.0 g / L, 10.5 g / L, 11.0 g / L, 11.5 g / L, or 12.0 g / L.

[0043] In some alternative embodiments, the carbonation continuous decomposition includes a first decomposition stage, a second decomposition stage, a third decomposition stage, a fourth decomposition stage, and a fifth decomposition stage.

[0044] The aluminum oxide concentration of the first decomposition stage is 70 g / L to 80 g / L, the aluminum oxide concentration of the second decomposition stage is 50 g / L to 60 g / L, the aluminum oxide concentration of the third decomposition stage is 30 g / L to 40 g / L, the aluminum oxide concentration of the fourth decomposition stage is 20 g / L to 30 g / L, and the aluminum oxide concentration of the fifth decomposition stage is 10 g / L to 12 g / L.

[0045] In the embodiments of the present application, by refining the number of specific stages of carbonation continuous decomposition, the carbonation decomposition through five stages can be determined, and the coarse particle aluminum hydroxide slurry with uniform aluminum oxide concentration can be obtained.

[0046] The aluminum oxide concentration of the first decomposition stage can be 70 g / L, 71 g / L, 72 g / L, 73 g / L, 74 g / L, 75 g / L, 76 g / L, 77 g / L, 78 g / L, 79 g / L, or 80 g / L.

[0047] The aluminum oxide concentration of the second decomposition stage can be 50 g / L, 51 g / L, 52 g / L, 53 g / L, 54 g / L, 55 g / L, 56 g / L, 57 g / L, 58 g / L, 59 g / L, or 60 g / L.

[0048] The aluminum oxide concentration of the third decomposition stage can be 30 g / L, 31 g / L, 32 g / L, 33 g / L, 34 g / L, 35 g / L, 36 g / L, 37 g / L, 38 g / L, 39 g / L, or 40 g / L.

[0049] The aluminum oxide concentration of the fourth decomposition stage can be 20 g / L, 21 g / L, 22 g / L, 23 g / L, 24 g / L, 25 g / L, 26 g / L, 27 g / L, 28 g / L, 29 g / L, or 30 g / L.

[0050] The aluminum oxide concentration of the fifth decomposition stage can be 10 g / L, 10.5 g / L, 11.0 g / L, 11.5 g / L, or 12.0 g / L.

[0051] In some optional embodiments, the screen used in the multi-stage continuous screening has a mesh size of 30-70 mesh.

[0052] In some optional embodiments, the screen used in the multi-stage continuous screening has a rotational speed of 500-900 r / min.

[0053] In the embodiments, the specific mesh size and specific rotational speed of the screen used in the multi-stage continuous screening can further separate aluminum hydroxide of different particle sizes by multi-stage screening, thereby facilitating subsequent precise grading to obtain high-quality coarse-grained aluminum hydroxide products.

[0054] The screen used in the multi-stage continuous screening can have a mesh size of 30 mesh, 35 mesh, 40 mesh, 45 mesh, 50 mesh, 55 mesh, 60 mesh, 65 mesh, or 70 mesh.

[0055] The screen used in the multi-stage continuous screening can have a rotational speed of 500 r / min, 550 r / min, 600 r / min, 650 r / min, 700 r / min, 750 r / min, 800 r / min, 850 r / min, or 900 r / min.

[0056] In some optional embodiments, the multi-stage continuous screening includes first screening, second screening, third screening, fourth screening, and fifth screening; the mesh size of the screens used in the first screening, second screening, third screening, fourth screening, and fifth screening is distributed in an increasing order.

[0057] In some optional embodiments, the screen used in the first screening has a rotational speed of 800-900 r / min, the screen used in the second screening has a rotational speed of 650-750 r / min, the screen used in the third screening has a rotational speed of 600-700 r / min, the screen used in the fourth screening has a rotational speed of 550-650 r / min, and the screen used in the fifth screening has a rotational speed of 500-600 r / min.

[0058] In the embodiment of the present application, by refining the specific stage quantity of multi-stage continuous screening, the particle size of aluminum hydroxide can be further accurately graded through staged screening, and coarse particle size aluminum hydroxide products meeting the expected particle size can be conveniently obtained through subsequent air separation.

[0059] The rotational speed of the screen used for the first screening can be 800 r / min, 810 r / min, 820 r / min, 830 r / min, 840 r / min, 850 r / min, 860 r / min, 870 r / min, 880 r / min, 890 r / min, or 900 r / min.

[0060] The rotational speed of the screen used for the second screening can be 650 r / min, 660 r / min, 670 r / min, 680 r / min, 690 r / min, 700 r / min, 710 r / min, 720 r / min, 730 r / min, 740 r / min, or 750 r / min.

[0061] The rotational speed of the screen used for the third screening can be 600 r / min, 610 r / min, 620 r / min, 630 r / min, 640 r / min, 650 r / min, 660 r / min, 670 r / min, 680 r / min, 690 r / min, or 700 r / min.

[0062] The rotational speed of the screen used for the fourth screening can be 550 r / min, 560 r / min, 570 r / min, 580 r / min, 590 r / min, 600 r / min, 610 r / min, 620 r / min, 630 r / min, 640 r / min, or 650 r / min.

[0063] The rotational speed of the screen used for the fourth screening can be 500 r / min, 510 r / min, 520 r / min, 530 r / min, 540 r / min, 550 r / min, 560 r / min, 570 r / min, 580 r / min, 590 r / min, or 600 r / min.

[0064] In some optional embodiments, the air door opening degree used in the multi-stage wind selection is 20% to 70%.

[0065] In the embodiments of the present application, by refining the specific air door opening degree in multi-stage wind selection, the particle size of aluminum hydroxide can be further accurately graded by wind selection, so as to obtain high-quality coarse-grained aluminum hydroxide products.

[0066] The air door opening degree used in the multi-stage wind selection can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70%.

[0067] In some optional embodiments, the multi-stage wind selection includes first wind selection, second wind selection, third wind selection, fourth wind selection, and fifth wind selection.

[0068] The air door opening degree used in the first wind selection is 60% to 70%, the air door opening degree used in the second wind selection is 40% to 45%, the air door opening degree used in the third wind selection is 35% to 40%, the air door opening degree used in the fourth wind selection is 30% to 35%, and the air door opening degree used in the fifth wind selection is 20% to 30%.

[0069] In the embodiments of the present application, by refining the number of specific stages of multi-stage continuous wind selection, the particle size of the screened aluminum hydroxide can be further accurately graded by stage-by-stage wind selection, so as to obtain high-quality coarse-grained aluminum hydroxide products.

[0070] The air door opening degree used in the first wind selection can be 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, or 70%.

[0071] The air door opening degree used in the second wind selection can be 40%, 41%, 42%, 43%, 44%, or 45%.

[0072] The air door opening degree used in the third wind selection can be 35%, 36%, 37%, 38%, 39%, or 40%.

[0073] The air door opening degree used in the fourth wind selection can be 30%, 31%, 32%, 33%, 34%, or 35%.

[0074] The air door opening degree of the fifth winnowing can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%.

[0075] In some alternative embodiments, the particle size of the aluminum hydroxide in the coarse-grained aluminum hydroxide slurry is 120-240 μm, and the weight concentration of the aluminum hydroxide in the coarse-grained aluminum hydroxide slurry is 45%-70%.

[0076] In the embodiments of the present application, by refining the specific particle size and specific weight concentration of the aluminum hydroxide in the coarse-grained aluminum hydroxide product, the content and particle size characteristics of the aluminum hydroxide in the coarse-grained aluminum hydroxide slurry obtained after continuous decomposition by carbonation can be determined, which facilitates subsequent accurate classification of the aluminum hydroxide by drying, multi-stage screening, and multi-stage winnowing, thereby obtaining a high-quality coarse-grained aluminum hydroxide product.

[0077] The particle size of the aluminum hydroxide in the coarse-grained aluminum hydroxide slurry can be 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, 210 μm, 220 μm, 230 μm, or 240 μm.

[0078] The weight concentration of the aluminum hydroxide in the coarse-grained aluminum hydroxide slurry can be 45%, 50%, 55%, 60%, 65%, or 70%.

[0079] The present application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. The experimental methods in the following examples, if not specified, are generally determined according to national standards. If there is no corresponding national standard, the general international standard, conventional conditions, or the conditions recommended by the manufacturer are used.

[0080] Example 1

[0081] As shown in Figure 1 A method for preparing coarse-grained aluminum hydroxide, comprising:

[0082] S1. continuously decomposing a sodium aluminate solution by carbonation to obtain a coarse-grained aluminum hydroxide slurry;

[0083] S2. performing multi-stage continuous screening and multi-stage winnowing on the coarse-grained aluminum hydroxide slurry to obtain a high-quality coarse-grained aluminum hydroxide product;

[0084] The carbonation continuous decomposition includes continuous decomposition in a manner of gradiently decreasing the aluminum oxide concentration.

[0085] As shown in Figure 2 The carbonation continuous decomposition includes a first decomposition stage, a second decomposition stage, a third decomposition stage, a fourth decomposition stage and a fifth decomposition stage.

[0086] The aluminum oxide concentration of the first decomposition stage is 75 g / L, the aluminum oxide concentration of the second decomposition stage is 55 g / L, the aluminum oxide concentration of the third decomposition stage is 35 g / L, the aluminum oxide concentration of the fourth decomposition stage is 25 g / L, and the aluminum oxide concentration of the fifth decomposition stage is 11 g / L.

[0087] The multi-stage continuous screening includes a first screening, a second screening, a third screening, a fourth screening and a fifth screening; the aperture of the screen used in the first screening, the aperture of the screen used in the second screening, the aperture of the screen used in the third screening, the aperture of the screen used in the fourth screening and the aperture of the screen used in the fifth screening are

[0088] The rotating speed of the screen used in the first screening is 850 r / min, the rotating speed of the screen used in the second screening is 700 r / min, the rotating speed of the screen used in the third screening is 650 r / min, the rotating speed of the screen used in the fourth screening is 600 r / min, and the rotating speed of the screen used in the fifth screening is 550 r / min.

[0089] The multi-stage air separation includes a first air separation, a second air separation, a third air separation, a fourth air separation and a fifth air separation.

[0090] The opening degree of the air door used in the first air separation is 65%, the opening degree of the air door used in the second air separation is 42%, the opening degree of the air door used in the third air separation is 37%, the opening degree of the air door used in the fourth air separation is 33%, and the opening degree of the air door used in the fifth air separation is 25%.

[0091] The particle size of the aluminum hydroxide in the coarse-grained aluminum hydroxide slurry is 120 μm to 240 μm, and the weight concentration of the aluminum hydroxide in the coarse-grained aluminum hydroxide slurry is 45% to 70%.

[0092] Example 2

[0093] Comparing Example 2 with Example 1, the difference between Example 2 and Example 1 is that:

[0094] The aluminum oxide concentration of the first decomposition stage is 70 g / L, the aluminum oxide concentration of the second decomposition stage is 50 g / L, the aluminum oxide concentration of the third decomposition stage is 30 g / L, the aluminum oxide concentration of the fourth decomposition stage is 20 g / L, and the aluminum oxide concentration of the fifth decomposition stage is 10 g / L.

[0095] The rotating speed of the screen used in the first screening is 800 r / min, the rotating speed of the screen used in the second screening is 650 r / min, the rotating speed of the screen used in the third screening is 600 r / min, the rotating speed of the screen used in the fourth screening is 550 r / min, and the rotating speed of the screen used in the fifth screening is 500 r / min.

[0096] The opening degree of the air door used in the first winnowing is 60%, the opening degree of the air door used in the second winnowing is 40%, the opening degree of the air door used in the third winnowing is 35%, the opening degree of the air door used in the fourth winnowing is 30%, and the opening degree of the air door used in the fifth winnowing is 20%.

[0097] Example 3

[0098] Comparing Example 3 with Example 1, the difference between Example 3 and Example 1 is that:

[0099] The aluminum oxide concentration of the first decomposition stage is 80 g / L, the aluminum oxide concentration of the second decomposition stage is 60 g / L, the aluminum oxide concentration of the third decomposition stage is 40 g / L, the aluminum oxide concentration of the fourth decomposition stage is 30 g / L, and the aluminum oxide concentration of the fifth decomposition stage is 12 g / L.

[0100] The rotating speed of the screen used in the first screening is 900 r / min, the rotating speed of the screen used in the second screening is 750 r / min, the rotating speed of the screen used in the third screening is 700 r / min, the rotating speed of the screen used in the fourth screening is 650 r / min, and the rotating speed of the screen used in the fifth screening is 600 r / min.

[0101] The opening degree of the air door used in the first winnowing is 70%, the opening degree of the air door used in the second winnowing is 45%, the opening degree of the air door used in the third winnowing is 40%, the opening degree of the air door used in the fourth winnowing is 35%, and the opening degree of the air door used in the fifth winnowing is 30%.

[0102] Comparative Example 1

[0103] Comparing Comparative Example 1 with Example 1, the difference between Comparative Example 1 and Example 1 is that:

[0104] Instead of using carbonation continuous decomposition, multi-stage screening and multi-stage winnowing, one-time carbonation decomposition, screening and winnowing are directly used.

[0105] Related experiments and effect data:

[0106] The aluminum hydroxide products obtained from Example 1 and Comparative Example 1 are observed by scanning electron microscope, and the results are as follows: Figure 3 and Figure 4As shown, the crystal form of the aluminum hydroxide product obtained by the comparative example 1 not using the method of the present application is not perfect, the crystal size is not uniform and the shape is irregular, while the crystal of the aluminum hydroxide product obtained by the example 1 using the method of the present application is more perfect, the size is uniform and the shape is more regular, and the large particle aluminum hydroxide raw material with concentrated distribution can be prepared.

[0107] The method of example 1 is used to treat different batches of sodium aluminate solution for multiple times, and the coarse particle aluminum hydroxide products obtained finally are detected, and the results are shown in table 1.

[0108] Table 1: Indexes of coarse particle aluminum hydroxide products after treatment of sodium aluminate solution of each batch

[0109]

[0110]

[0111] As shown in table 1, by using the method for preparing coarse particle aluminum hydroxide provided in the example of the present application, the particle size of the obtained aluminum hydroxide product is coarse and the distribution is concentrated, and by using the sorting process provided by the method, the high-quality coarse particle aluminum hydroxide products with different particle sizes required can be obtained to meet the particle size range requirements of different customers.

[0112] In summary, by using the method for preparing coarse particle aluminum hydroxide provided in the example of the present application, the continuous carbonation and decomposition are introduced in the existing sodium aluminate decomposition stage on the basis of not changing the existing production process, and the aluminum oxide concentration is controlled to decrease in a gradient manner in the process of continuous carbonation and decomposition, and then the particle size of the aluminum hydroxide in the coarse particle aluminum hydroxide slurry can be further accurately graded by using the multi-stage continuous screening and multi-stage air classification, so that the high-quality coarse particle aluminum hydroxide product with particle size d50≥220μm can be obtained.

[0113] The one or more technical solutions in the example of the present application have at least the following technical effects or advantages:

[0114] (1) The method for preparing coarse particle aluminum hydroxide provided in the example of the present application uses the method of continuous carbonation and decomposition, controls the decomposition process of the aluminum oxide concentration of each decomposition tank, and can obtain a large amount of coarse particle aluminum hydroxide slurry, and then realizes accurate grading by using the multi-stage screening and multi-stage air classification, and then performs drying to obtain the high-quality coarse particle aluminum hydroxide product.

[0115] (2) The method for preparing coarse particle aluminum hydroxide provided in the example of the present application accurately grades the dried aluminum hydroxide raw material by using the multi-stage screening and multi-stage air classification process, and obtains the high-quality coarse particle aluminum hydroxide with concentrated particle size of D10≥145μm, D50≥220μm and D90≥300μm.

[0116] (3) The preparation method of the coarse-grained aluminum hydroxide provided in the embodiment of the present application is grafted to the existing production process, and a new decomposition system process does not need to be newly added, and only the decomposition gradient needs to be effectively adjusted and controlled, so that a large amount of investment can be saved.

[0117] (4) The preparation method of the coarse-grained aluminum hydroxide provided in the embodiment of the present application only needs to appropriately transform and optimize the existing screening process and negative pressure air separation system after the drying of the aluminum hydroxide raw material, so that the accurate particle size grading and sorting of the aluminum hydroxide raw material can be realized, and the process is simple and easy to operate.

[0118] Various embodiments of the present application can exist in the form of a range; it should be understood that the description in the form of a range is only for the convenience and brevity, and should not be understood as a hard limit on the scope of the present application; therefore, it should be considered that the described range has disclosed all possible sub-ranges and single values in the range. For example, it should be considered that the range description from 1 to 6 has 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., and single numbers in the range, such as 1, 2, 3, 4, 5 and 6, regardless of the range. In addition, whenever a numerical range is indicated in this document, it refers to any cited number (fraction or integer) in the indicated range.

[0119] In the present application, the orientation words such as "upper" and "lower" are specific to the drawing direction in the drawings. In addition, in the description of the specification, the terms "include", "contain" and the like mean "include but are not limited to".

[0120] In this document, relational terms such as "first" and "second", and the like, are used solely to distinguish one entity or action from another entity or action, without necessarily requiring or implying any such actual relationship or order between such entities or actions. In this document, "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent: A exists alone, A and B exist together, and B exists alone. Where A and B can be singular or plural. In this document, "one or more" means one or more, and "multiple" means two or more. "At least one", "at least one of the following" or the like means any combination of the items, including single item or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can mean a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0121] The foregoing detailed description of the application has been presented for purposes of illustration and description. Various modifications and changes can be made to these embodiments without departing from the spirit and scope of the application. It is intended that the scope of the application should not be limited by the particular representative embodiments described above.

Claims

1. A method for producing coarse-grained aluminum hydroxide, characterized by, The preparation method comprises: carbonating and continuously decomposing a sodium aluminate solution to obtain a coarse-grained aluminum hydroxide slurry; drying the coarse-grained aluminum hydroxide slurry, and then performing multi-stage continuous screening and multi-stage air separation to obtain a high-quality coarse-grained aluminum hydroxide product; The carbonating and continuously decomposing comprises continuously decomposing in a manner that the aluminum oxide concentration gradually decreases. The particle size of the coarse-grained aluminum hydroxide product satisfies D10≥145 μm, D50≥220 μm and D90≥300 μm. The initial aluminum oxide concentration of the carbonating and continuously decomposing is 110 g / L-130 g / L, and the final aluminum oxide concentration of the carbonating and continuously decomposing is 10 g / L-12 g / L. The carbonating and continuously decomposing comprises a first decomposition stage, a second decomposition stage, a third decomposition stage, a fourth decomposition stage and a fifth decomposition stage. The aluminum oxide concentrations of the first decomposition stage, the second decomposition stage, the third decomposition stage, the fourth decomposition stage and the fifth decomposition stage are 70 g / L-80 g / L, 50 g / L-60 g / L, 30 g / L-40 g / L, 20 g / L-30 g / L and 10 g / L-12 g / L, respectively. The multi-stage continuous screening comprises a first screening, a second screening, a third screening, a fourth screening and a fifth screening, and the rotational speeds of the screens used in the first screening, the second screening, the third screening, the fourth screening and the fifth screening are 800 r / min-900 r / min, 650 r / min-750 r / min, 600 r / min-700 r / min, 550 r / min-650 r / min and 500 r / min-600 r / min, respectively. The multi-stage air separation comprises a first air separation, a second air separation, a third air separation, a fourth air separation and a fifth air separation. The opening degrees of the air doors used in the first air separation, the second air separation, the third air separation, the fourth air separation and the fifth air separation are 60%-70%, 40%-45%, 35%-40%, 30%-35% and 20%-30%, respectively.

2. The production method according to claim 1, characterized by, The mesh size of the screen used in the multi-stage continuous screening is 30-70.

3. The preparation method according to claim 2, characterized in that, The multi-stage continuous screening comprises a first screening, a second screening, a third screening, a fourth screening and a fifth screening, and the mesh sizes of the screens used in the first screening, the second screening, the third screening, the fourth screening and the fifth screening are distributed in an increasing order.

4. The method of claim 1, wherein, The particle size of the aluminum hydroxide in the coarse-grained aluminum hydroxide slurry is 120 μm-240 μm, and the weight concentration of the aluminum hydroxide in the coarse-grained aluminum hydroxide slurry is 45%-70%.

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