Preparation method of high-white aluminum hydroxide

Abstract

The application relates to the technical field of aluminum material preparation, in particular to a preparation method of high-white aluminum hydroxide; the method comprises the following steps: mixing Bayer process aluminum hydroxide and a seed mother solution to obtain mixed slurry; performing a resolubilization reaction on the mixed slurry to obtain a sodium aluminate solution; diluting the sodium aluminate solution to a target alumina concentration and a target caustic ratio, then adding an inducer to obtain an induced sodium aluminate solution; performing an adsorption decolorization reaction on the induced sodium aluminate solution, then filtering to obtain sodium aluminate concentrate; diluting the sodium aluminate concentrate and adding aluminum hydroxide seed crystals to decompose, thereby obtaining a high-white aluminum hydroxide product; or, diluting the sodium aluminate concentrate and passing in carbon dioxide to decompose, thereby obtaining a high-white aluminum hydroxide product; the inducer comprises at least one of the following: aluminum hydroxide, magnesium hydroxide, zinc hydroxide, aluminum oxide, magnesium oxide and zinc oxide; the method can obtain a high-white aluminum hydroxide product under the condition of a simple process flow, and the product can replace sintered high-white aluminum hydroxide.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of aluminum material preparation, and in particular to a preparation method of high-white aluminum hydroxide. BACKGROUND

[0002] Currently, the production processes of aluminum hydroxide mainly include sintering and Bayer processes. However, in order to obtain aluminum hydroxide products with high whiteness, the sintering process is generally used to produce high-white aluminum hydroxide in the market. However, the sintering process consumes a large amount of fuel, has a complex production process, high cost and certain environmental pollution, which is contrary to the development planning requirements of low carbon, environmental protection and low energy consumption.

[0003] Therefore, at present, the Bayer process is tried to be used to produce high-white aluminum hydroxide products. However, the whiteness of aluminum hydroxide produced by the ordinary Bayer process is generally below 90%, and the aluminum hydroxide cannot be applied to the production of materials such as artificial stone, rubber and plastic products, and electric wires and cables which have high requirements on the whiteness of aluminum hydroxide. SUMMARY

[0004] The application provides a preparation method of high-white aluminum hydroxide, so as to solve the technical problem that the whiteness of aluminum hydroxide produced by the ordinary Bayer process is generally below 90% in the prior art.

[0005] In a first aspect, the application provides a preparation method of high-white aluminum hydroxide, and the method comprises the following steps:

[0006] Mixing Bayer process aluminum hydroxide and seed mother liquor to obtain a mixed slurry;

[0007] Subjecting the mixed slurry to a resolubilization reaction to obtain a sodium aluminate solution;

[0008] Diluting the sodium aluminate solution to a target alumina concentration and a target caustic ratio, and then adding an inducer to obtain an induced sodium aluminate solution;

[0009] Subjecting the induced sodium aluminate solution to an adsorption decolorization reaction, and then performing filtration to obtain a sodium aluminate concentrate;

[0010] Diluting the sodium aluminate concentrate and adding aluminum hydroxide seeds to decompose to obtain a high-white aluminum hydroxide product;

[0011] Or,

[0012] Diluting the sodium aluminate concentrate and passing carbon dioxide to decompose to obtain a high-white aluminum hydroxide product;

[0013] The inducer comprises at least one of the following:

[0014] Aluminum hydroxide, magnesium hydroxide, zinc hydroxide, aluminum oxide, magnesium oxide and zinc oxide.

[0015] Optionally, the mass ratio of the induced addition amount to the aluminum hydroxide in the sodium aluminate solution is 0.1% to 20%.

[0016] Optionally, the particle size of the induced agent is 0.5 μm to 50 μm.

[0017] Optionally, the temperature of the resolubilization reaction is 100°C to 150°C.

[0018] Optionally, the whiteness of the Bayer process aluminum hydroxide is 65% to 87%, and the particle size of the Bayer process aluminum hydroxide is 50 μm to 120 μm.

[0019] Optionally, the alumina concentration of the sodium aluminate solution is 150 g / L to 260 g / L, and the caustic ratio of the sodium aluminate solution is 1.30 to 1.80.

[0020] Optionally, the target alumina concentration is 8 g / L to 180 g / L.

[0021] The target caustic ratio is 1.30 to 1.80.

[0022] Optionally, the temperature of the adsorption decolorization reaction is 20°C to 70°C, and the time of the adsorption decolorization reaction is 0.5 h to 5 h.

[0023] Optionally, the mass ratio of the addition amount of the aluminum hydroxide seed to the aluminum hydroxide in the sodium aluminate liquor is 0.7% to 800%.

[0024] The median particle size of the aluminum hydroxide seed is 1.0 μm to 120 μm.

[0025] Optionally, the temperature of the decomposition is 50°C to 75°C, the time of the decomposition is 10 h to 100 h, and the median particle size of the target aluminum hydroxide of the decomposition is 0.9 μm to 100 μm.

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

[0027] The embodiment of the present application provides a preparation method of high-whiteness aluminum hydroxide, seed mother liquor is added into bayer method aluminum hydroxide to carry out resolubilization reaction, so that resolubilization sodium aluminate solution is obtained, an inducer is added into the resolubilization sodium aluminate solution, the inducer can make high-activity aluminum hydroxide decompose in the sodium aluminate solution, the aluminum hydroxide is used for adsorbing and decoloring treatment of organic matters in the sodium aluminate solution, and after filtration, the decolorized sodium aluminate solution is obtained, finally, the conventional decomposition is carried out by adding aluminum hydroxide seeds, and the high-whiteness aluminum hydroxide product can be obtained, compared with the traditional bayer method aluminum hydroxide, the high-whiteness aluminum hydroxide product is obtained, and the aluminum hydroxide formed in the resolubilization sodium aluminate solution of the bayer method aluminum hydroxide is used for adsorbing and decoloring treatment of organic matters, so that the high-whiteness aluminum hydroxide product can be obtained under the condition of simple process flow. BRIEF DESCRIPTION OF DRAWINGS

[0028] The drawings incorporated into the specification and constituting a part of the specification show embodiments consistent with the present application and, together with the specification, serve to explain the principles of the present application.

[0029] 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 below, and obviously, other drawings can also be obtained by those skilled in the art without creative labor under the premise of not paying creative labor.

[0030] Figure 1 A preparation method of high-whiteness aluminum hydroxide provided by the embodiment of the present application is shown in the flowchart.

[0031] Figure 2 Another preparation method of high-whiteness aluminum hydroxide provided by the embodiment of the present application is shown in the flowchart. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application, obviously, the described embodiments are a 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 belong to the protection scope of the present application.

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

[0034] For example, Figure 1 and Figure 2As shown, the embodiment of the present application provides a preparation method of high-white aluminum hydroxide, which comprises the following steps:

[0035] S1. mixing Bayer process aluminum hydroxide and seed mother solution to obtain mixed slurry;

[0036] S2. subjecting the mixed slurry to resolubilization reaction to obtain sodium aluminate solution;

[0037] S3. diluting the sodium aluminate solution to target alumina concentration and target caustic ratio, and then adding an inducing agent to obtain induced sodium aluminate solution;

[0038] S4. subjecting the induced sodium aluminate solution to adsorption decolorization reaction, and then performing filtration to obtain sodium aluminate concentrate;

[0039] S5. diluting the sodium aluminate concentrate and adding aluminum hydroxide seed to decompose to obtain high-white aluminum hydroxide product;

[0040] or,

[0041] S5. diluting the sodium aluminate concentrate and passing carbon dioxide to decompose to obtain high-white aluminum hydroxide product;

[0042] In the embodiment of the present application, the inducing agent comprises at least one of the following:

[0043] aluminum hydroxide, magnesium hydroxide, zinc hydroxide, aluminum oxide, magnesium oxide and zinc oxide.

[0044] It should be noted that the seed mother solution can be sodium hydroxide solution.

[0045] In some optional embodiments, the mass ratio of the added amount of the inducing agent to the aluminum hydroxide in the sodium aluminate solution is 0.1% to 20%.

[0046] In the embodiment of the present application, the specific mass ratio of the added amount of the inducing agent to the aluminum hydroxide in the sodium aluminate solution can be limited, so that the sodium aluminate solution is decomposed and high-activity aluminum hydroxide is formed by the addition of the inducing agent, which facilitates the subsequent adsorption decolorization process, so as to improve the whiteness of the final aluminum hydroxide product.

[0047] The induced addition amount and the mass ratio of aluminum hydroxide in the sodium aluminate solution can be 0.1%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, 10.0%, 10.5%, 11.0%, 11.5%, 12.0%, 12.5%, 13.0%, 13.5%, 14.0%, 14.5%, 15.0%, 15.5%, 16.0%, 16.5%, 17.0%, 17.5%, 18.0%, 18.5%, 19.0%, 19.5%, or 20.0%.

[0048] In some optional embodiments, the particle size of the inducer is 0.5 μm to 50 μm.

[0049] In the embodiments of the present application, the specific particle size of the inducer is limited, so that the inducer can be fully mixed with the sodium aluminate solution, and a sufficient amount of high-activity aluminum hydroxide product can be obtained.

[0050] The particle size of the inducer can be 0.5 μm, 1.0 μm, 2.0 μm, 5.0 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, or 50 μm.

[0051] In some optional embodiments, the temperature of the resolubilization reaction is 100°C to 150°C.

[0052] In the embodiments of the present application, the specific temperature of the resolubilization reaction is limited, so that the Bayer process aluminum hydroxide can be dissolved by the seed mother solution, on the one hand, a sodium aluminate solution with sufficient alumina concentration can be obtained, and on the other hand, sufficient sodium elements can be introduced, which facilitates the subsequent addition of the inducer to obtain a sufficient amount of high-activity aluminum hydroxide.

[0053] The temperature of the resolubilization reaction can be 100°C, 110°C, 120°C, 130°C, 140°C, or 150°C.

[0054] In some optional embodiments, the whiteness of the Bayer process aluminum hydroxide is 65% to 87%, and the particle size of the Bayer process aluminum hydroxide is 50 μm to 120 μm.

[0055] In the embodiments of the present application, the specific whiteness and specific particle size of the Bayer process aluminum hydroxide are limited, on the one hand, the Bayer process aluminum hydroxide can be dissolved by the seed mother solution, so that a sufficient amount of high-activity aluminum hydroxide product can be obtained, and on the other hand, a high-whiteness aluminum hydroxide product can be finally obtained on the basis of the whiteness.

[0056] The whiteness of the Bayer process aluminum hydroxide can be 65%, 67%, 69%, 71%, 73%, 75%, 77%, 79%, 81%, 83%, 85%, or 87%.

[0057] The particle size of the Bayer process aluminum hydroxide can be 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, or 120 μm.

[0058] In some alternative embodiments, the aluminate solution has an alumina concentration of 150 g / L to 260 g / L, and a caustic ratio of 1.30 to 1.80.

[0059] In the embodiments of the present application, the specific alumina concentration and the specific caustic ratio of the aluminate solution are defined, the specific properties of the aluminate solution can be determined, the aluminate solution can be reacted with the inducer, and thus a sufficient amount of high-activity aluminum hydroxide can be obtained, facilitating the subsequent adsorption and decolorization reaction.

[0060] The alumina concentration of the aluminate solution can be 150 g / L, 160 g / L, 170 g / L, 180 g / L, 190 g / L, 200 g / L, 210 g / L, 220 g / L, 230 g / L, 240 g / L, 250 g / L, or 260 g / L.

[0061] The caustic ratio of the aluminate solution can be 1.30, 1.40, 1.50, 1.60, 1.70, or 1.80.

[0062] In some alternative embodiments, the target alumina concentration is 8 g / L to 180 g / L.

[0063] The target caustic ratio is 1.30 to 1.80.

[0064] In the embodiments of the present application, the specific target alumina concentration and the specific target caustic ratio are defined, which facilitates the reaction of the aluminate solution with the inducer, and thus an aluminate solution containing a sufficient amount of alumina concentration can be obtained.

[0065] The target alumina concentration can be 8 g / L, 10 g / L, 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L, 150 g / L, 160 g / L, 170 g / L, or 180 g / L.

[0066] The target caustic ratio can be 1.30, 1.40, 1.50, 1.60, 1.70, or 1.80.

[0067] In some alternative embodiments, the adsorption decoloring reaction has a temperature of 20-70°C, and a time of 0.5-5 hours.

[0068] In the embodiments of the present application, the specific temperature and time of the adsorption decoloring reaction can make the highly active aluminum hydroxide fully adsorb the organic substances in the sodium aluminate solution, thereby improving the whiteness of the final aluminum hydroxide product.

[0069] The temperature of the adsorption decoloring reaction can be 20°C, 30°C, 40°C, 50°C, 60°C, or 70°C.

[0070] The time of the adsorption decoloring reaction can be 0.5h, 1.0h, 1.5h, 2.0h, 2.5h, 3.0h, 3.5h, 4.0h, 4.5h, or 5.0h.

[0071] In some alternative embodiments, the mass ratio of the amount of the aluminum hydroxide seed crystals added to the aluminum hydroxide in the sodium aluminate liquor is 0.7%-800%;

[0072] The medium particle size of the aluminum hydroxide seed crystals is 1.0-120μm.

[0073] In the embodiments of the present application, the specific mass ratio of the amount of the aluminum hydroxide seed crystals added to the aluminum hydroxide in the sodium aluminate liquor and the specific medium particle size of the aluminum hydroxide seed crystals can make the sodium aluminate liquor completely decompose under the action of the aluminum hydroxide seed crystals, thereby obtaining the aluminum hydroxide product with high whiteness.

[0074] The mass ratio of the amount of the aluminum hydroxide seed crystals added to the aluminum hydroxide in the sodium aluminate liquor can be 0.7%, 1.0%, 5.0%, 10.0%, 15.0%, 20.0%, 30.0%, 40.0%, 50.0%, 60.0%, 80.0%, 100.0%, 150.0%, 200.0%, 250.0%, 300.0%, 350.0%, 400.0%, 450.0%, 500.0%, 550.0%, 600.0%, 650.0%, 700.0%, 750.0%, or 800.0%.

[0075] 250.0%, 300.0%, 350.0%, 400.0%, 450.0%, 500.0%, 550.0%, 600.0%, 650.0%, 700.0%, 750.0%, or 800.0%.

[0076] In some alternative embodiments, the decomposition has a temperature of 50-75°C, a time of 10-100 hours, and a target aluminum hydroxide with a medium particle size of 0.9-100μm.

[0077] In the embodiments of the present application, the specific temperature and time of the decomposition can make the sodium aluminate liquor completely decompose under the action of the aluminum hydroxide seed crystals, thereby obtaining the aluminum hydroxide product with high whiteness.

[0078] The temperature of the decomposition can be 50°C, 55°C, 60°C, 65°C, 70°C, or 75°C.

[0079] The time of the decomposition can be 10h, 20h, 30h, 40h, 50h, 60h, 70h, 80h, 90h, or 100h.

[0080] The target median particle size of the aluminum hydroxide of the decomposition can be 0.9pm, 1.0pm, 5.0pm, 10.0pm, 20.0pm, 30.0pm, 40.0pm, 50.0pm, 60.0pm, 70.0pm, 80.0pm, 90.0pm, or 100.0pm.

[0081] The present application is further described in conjunction with the following specific examples. It should be understood that these examples are only intended to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods in the following examples, if not otherwise specified, are generally determined according to the industry standards. If there is no corresponding industry standard, the determination is made according to the general international standards, the conventional conditions, or according to the conditions suggested by the manufacturer.

[0082] Example 1

[0083] As shown in Figure 1 A method for preparing high-white aluminum hydroxide includes:

[0084] 1. mixing Bayer process aluminum hydroxide and seed mother solution sodium hydroxide to obtain a mixed slurry, and allowing the mixed slurry to undergo a reslurry reaction to obtain a Bayer process aluminum hydroxide reslurried sodium aluminate solution;

[0085] 2. adding aluminum hydroxide solid with a particle size of 0.5pm as an inducer to the Bayer process aluminum hydroxide reslurried sodium aluminate solution, the sodium aluminate solution having an alumina concentration of 80g / L and a caustic ratio of 1.30, the inducer being added in an amount of 0.1% of the mass of the aluminum hydroxide in the sodium aluminate solution, the sodium aluminate solution to which the inducer is added being subjected to an adsorption decolorization reaction at 20°C for a reaction time of 1.2h, the sodium aluminate solution having a decomposition rate of 4.5%, and the solution being filtered to obtain a sodium aluminate concentrate.

[0086] 3. adding aluminum hydroxide seed crystals with a particle size (d50) of 1.5pm to the decolorized sodium aluminate solution in an amount of 1.3% of the aluminum hydroxide content in the sodium aluminate solution, and subjecting the solution to liquid-solid separation after stirring at 60°C for 20h, the solid being washed and dried to obtain an aluminum hydroxide product. The aluminum hydroxide product has a particle size (d50) of 0.99pm and a whiteness of 97.1%.

[0087] Example 2

[0088] As shown in Figure 1As shown in the figure, a high-white aluminum hydroxide preparation method comprises:

[0089] 1. Mixing Bayer process aluminum hydroxide and seed mother liquor solution sodium hydroxide to obtain mixed slurry, and making the mixed slurry undergo resolubilization reaction to obtain Bayer process aluminum hydroxide resolubilized sodium aluminate solution;

[0090] 2. Alumina solid with a particle size of 5 μm is added as an inducer to the Bayer process aluminum hydroxide resolubilized sodium aluminate solution, the alumina concentration of the sodium aluminate solution is 100 g / L, the caustic ratio is 1.40, the inducer is added in an amount of 1.5% of the mass of aluminum hydroxide in the sodium aluminate solution, the sodium aluminate solution to which the inducer is added is subjected to adsorption decolorization reaction at 70°C, the reaction time is 5 h, the sodium aluminate solution decomposition rate is 6.8%, and after the solution is filtered, sodium aluminate concentrate is obtained.

[0091] 3. Hydroxide aluminum seed with a particle size (d50) of 50 μm is added to the decolorized sodium aluminate solution in an amount of 300% of the aluminum hydroxide content in the sodium aluminate solution, and after stirring at 64°C for 35 h, liquid-solid separation is performed, the solid is washed and dried to obtain aluminum hydroxide product. The particle size (d50) of the aluminum hydroxide product is 52.6 μm, and the whiteness is 94.2%.

[0092] Example 3

[0093] As shown in the figure, a high-white aluminum hydroxide preparation method comprises: Figure 1

[0094] 1. Mixing Bayer process aluminum hydroxide and seed mother liquor solution sodium hydroxide to obtain mixed slurry, and making the mixed slurry undergo resolubilization reaction to obtain Bayer process aluminum hydroxide resolubilized sodium aluminate solution;

[0095] 2. A mixture of magnesium hydroxide solid and zinc hydroxide solid (mass ratio 1:1) with a particle size of 10 μm is added as an inducer to the Bayer process aluminum hydroxide resolubilized sodium aluminate solution, the alumina concentration of the sodium aluminate solution is 120 g / L, the caustic ratio is 1.55, the inducer is added in an amount of 2.5% of the mass of aluminum hydroxide in the sodium aluminate solution, the sodium aluminate solution to which the inducer is added is subjected to adsorption decolorization reaction at 30°C, the reaction time is 2 h, the sodium aluminate solution decomposition rate is 8.2%, and after the solution is filtered, sodium aluminate concentrate is obtained.

[0096] 3. Hydroxide aluminum seed with a particle size (d50) of 32.5 μm is added to the decolorized sodium aluminate solution in an amount of 400% of the aluminum hydroxide content in the sodium aluminate solution, and after stirring at 60°C for 55 h, liquid-solid separation is performed, the solid is washed and dried to obtain aluminum hydroxide product. The particle size (d50) of the aluminum hydroxide product is 34.8 μm, and the whiteness is 94.8%.

[0097] Example 4​

[0098] As shown in Figure 1 A method for preparing high-whiteness aluminum hydroxide, comprising:

[0099] 1. mixing Bayer-process aluminum hydroxide and seed mother liquor sodium hydroxide to obtain a mixed slurry, and allowing the mixed slurry to undergo reslurry reaction to obtain a reslurried sodium aluminate solution of the Bayer-process aluminum hydroxide;

[0100] 2. adding magnesium oxide solid with a particle size of 25 μm as an inducer to the reslurried sodium aluminate solution of the Bayer-process aluminum hydroxide, the sodium aluminate solution having an alumina concentration of 160 g / L and a caustic ratio of 1.45, the inducer being added in an amount of 5.5% of the mass of the aluminum hydroxide in the sodium aluminate solution, and the sodium aluminate solution with the inducer being subjected to adsorption decolorization reaction at 40°C for 2.5 h, the sodium aluminate solution having a decomposition rate of 7.2%, and the solution being filtered to obtain sodium aluminate concentrate.

[0101] 3. adding aluminum hydroxide seed with a particle size (d50) of 2.7 μm to the decolored sodium aluminate solution in an amount of 1.2% of the aluminum hydroxide content in the sodium aluminate solution, and performing liquid-solid separation after stirring at 62°C for 30 h, and obtaining aluminum hydroxide product after washing and drying the solid. The aluminum hydroxide product has a particle size (d50) of 5.9 μm and a whiteness of 95.9%.

[0102] Example 5

[0103] As shown in Figure 1 A method for preparing high-whiteness aluminum hydroxide, comprising:

[0104] 1. mixing Bayer-process aluminum hydroxide and seed mother liquor sodium hydroxide to obtain a mixed slurry, and allowing the mixed slurry to undergo reslurry reaction to obtain a reslurried sodium aluminate solution of the Bayer-process aluminum hydroxide;

[0105] 2. adding zinc oxide solid with a particle size of 40 μm as an inducer to the reslurried sodium aluminate solution of the Bayer-process aluminum hydroxide, the sodium aluminate solution having an alumina concentration of 170 g / L and a caustic ratio of 1.52, the inducer being added in an amount of 5.5% of the mass of the aluminum hydroxide in the sodium aluminate solution, and the sodium aluminate solution with the inducer being subjected to adsorption decolorization reaction at 60°C for 3.5 h, the sodium aluminate solution having a decomposition rate of 5.5%, and the solution being filtered to obtain sodium aluminate concentrate.

[0106] 3. adding aluminum hydroxide seed with a particle size (d50) of 96.6 μm to the decolored sodium aluminate solution in an amount of 500% of the aluminum hydroxide content in the sodium aluminate solution, and performing liquid-solid separation after stirring at 55°C for 55 h, and obtaining aluminum hydroxide product after washing and drying the solid. The aluminum hydroxide product has a particle size (d50) of 98.2 μm and a whiteness of 92.5%.

[0107] Example 6

[0108] As Figure 2 shown, a method for preparing high-white aluminum hydroxide includes:

[0109] 1. mixing Bayer process aluminum hydroxide and seed mother liquor sodium hydroxide to obtain a mixed slurry, and allowing the mixed slurry to undergo a reslurry reaction to obtain a Bayer process aluminum hydroxide reslurried sodium aluminate solution;

[0110] 2. adding aluminum hydroxide and aluminum oxide solids (mass ratio 1:1) with a particle size of 50 μm as an inducer to the Bayer process aluminum hydroxide reslurried sodium aluminate solution, the aluminum oxide concentration of the sodium aluminate solution being 180 g / L, the caustic ratio being 1.8, the inducer being added in an amount of 20% of the mass of the aluminum hydroxide in the sodium aluminate solution, the sodium aluminate solution to which the inducer is added being subjected to an adsorption decolorization reaction at 70°C, the reaction time being 5 h, the sodium aluminate solution having a decomposition rate of 9.8%, and the sodium aluminate solution being filtered to obtain a sodium aluminate concentrate.

[0111] 3. passing carbon dioxide gas into the decolored sodium aluminate solution at a temperature of 85°C, and after 5 h of aeration and stirring, performing liquid-solid separation, and drying the solid to obtain aluminum hydroxide product. The aluminum hydroxide product has a particle size (d50) of 74.5 μm and a whiteness of 93.2%.

[0112] Comparative Example 1

[0113] A method for preparing high-white aluminum hydroxide includes:

[0114] adding aluminum hydroxide seed crystals with a particle size (d50) of 1.2 μm to a Bayer process aluminum hydroxide reslurried sodium aluminate solution having a caustic ratio of 1.52 and an Al2O3 concentration of 90 g / L, the amount of addition being 1.3% of the aluminum hydroxide content in the sodium aluminate solution, stirring at 60°C for 20 h, and then performing liquid-solid separation, and drying the solid to obtain aluminum hydroxide product; the aluminum hydroxide has a particle size (d50) of 0.96 μm and a whiteness of 89.5%.

[0115] Comparative Example 2

[0116] A method for preparing high-white aluminum hydroxide includes:

[0117] adding aluminum hydroxide seed crystals with a particle size (d50) of 32.5 μm to a Bayer process aluminum hydroxide reslurried sodium aluminate solution having a caustic ratio of 1.55 and an Al2O3 concentration of 120 g / L, the amount of addition being 200% of the aluminum hydroxide content in the sodium aluminate solution, stirring at 60°C for 55 h, and then performing liquid-solid separation, and drying the solid to obtain aluminum hydroxide product; the aluminum hydroxide has a particle size (d50) of 33.1 μm and a whiteness of 87.3%.

[0118] Comparative Example 3

[0119] A method for preparing high-whiteness aluminum hydroxide, comprising:

[0120] A sodium aluminate solution is prepared by redissolving Bayer-process aluminum hydroxide with a caustic ratio of 1.52 and an Al2O3 concentration of 170 g / L, and then aluminum hydroxide seed crystals with a particle size (d50) of 75 μm are added in an amount of 400% of the aluminum hydroxide content in the sodium aluminate solution. After stirring at 55°C for 55 h, liquid-solid separation is performed, and the solid is washed and dried to obtain an aluminum hydroxide product. The particle size (d50) of the aluminum hydroxide is 76.5 μm, and the whiteness is 85.6%.

[0121] Comparative Example 4

[0122] A method for preparing high-whiteness aluminum hydroxide, comprising:

[0123] A sodium aluminate solution is prepared by redissolving Bayer-process aluminum hydroxide with a caustic ratio of 1.45 and an Al2O3 concentration of 135 g / L at a temperature of 80°C, and then carbon dioxide gas is bubbled into the solution. After stirring for 5 h, liquid-solid separation is performed, and the solid is washed and dried to obtain an aluminum hydroxide product. The particle size (d50) of the aluminum hydroxide is 98.3 μm, and the whiteness is 84.8%.

[0124] Related experiments and effect data:

[0125] The particle size (d50) and whiteness of the ultrafine aluminum hydroxide obtained in Examples 1-6 and Comparative Examples 1-4 are detected, and the results are shown in Table 1.

[0126] Table 1 Particle size and whiteness data of ultrafine aluminum hydroxide obtained in each example and comparative example

[0127]

[0128] As can be seen from Table 1, the method for preparing high-whiteness aluminum hydroxide provided in the examples of the present application adds an inducer to a sodium aluminate solution prepared by redissolving Bayer-process aluminum hydroxide, and high-activity aluminum hydroxide is precipitated from the sodium aluminate solution to adsorb and decolorize organic matter in the solution. The decolorized sodium aluminate solution is used to produce high-whiteness aluminum hydroxide using a conventional aluminum hydroxide precipitation process. Since the method only adds an organic matter adsorption and decolorization process, the overall process is simple and easy to operate.

[0129] Meanwhile, the high-white aluminum hydroxide product prepared by the method has a particle size (d50) of 0.9-100 μm and a whiteness of ≥92%, and can replace sintered high-white aluminum hydroxide as a filler for materials such as artificial stone, rubber and plastic products, and electric wires and cables, to play a role in filling and flame retardation, and solve the defects that ordinary Bayer-process aluminum hydroxide cannot be applied to some industries due to low whiteness, and the current situation of high production cost and high pollutant emission of sintered high-white aluminum hydroxide.

[0130] Meanwhile, the high-white aluminum hydroxide product prepared by the method has a particle size (d50) of 0.9-100 μm and a whiteness of ≥92%, and can replace sintered high-white aluminum hydroxide as a filler for materials such as artificial stone, rubber and plastic products, and electric wires and cables, to play a role in filling and flame retardation, and solve the defects that ordinary Bayer-process aluminum hydroxide cannot be applied to some industries due to low whiteness, and the current situation of high production cost and high pollutant emission of sintered high-white aluminum hydroxide.

[0131] Various embodiments of the present application can exist in a range of forms; it should be understood that the description in a range of forms is merely for the convenience and brevity, and should not be understood as a hard limitation on the scope of the present application; therefore, it should be considered that the described range has been specifically disclosed all possible sub-ranges and single values within the range. For example, it should be considered that the range description from 1 to 6 has 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., and single numbers within the described range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. In addition, whenever a numerical range is indicated in the present application, it refers to any cited number (fraction or integer) within the indicated range.

[0132] In the present application, the orientation words such as "upper" and "lower" are specifically the directions of the drawing surface in the drawings, unless otherwise stated. In addition, in the description of the present application, the terms "include", "contain" and the like mean "include but are not limited to". In the present text, the relationship terms such as "first" and "second" are merely 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 the entities or operations. In the present text, "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 the cases of A alone, A and B together, and B alone. Wherein A, B can be singular or plural. In the present text, "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 these items, including any combination of single 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, c can be single or multiple.

[0133] 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 high-white aluminum hydroxide, characterized by, The method comprises: S1. mixing Bayer process aluminum hydroxide and seed mother liquor solution to obtain a mixed slurry; S2. subjecting the mixed slurry to a reslurry reaction to obtain a sodium aluminate solution; S3. diluting the sodium aluminate solution to a target alumina concentration and a target caustic ratio, and then adding an inducer to obtain an induced sodium aluminate solution; S4. subjecting the induced sodium aluminate solution to an adsorption decolorization reaction, and then filtering to obtain a sodium aluminate concentrate; S5. diluting the sodium aluminate concentrate and adding aluminum hydroxide seeds for decomposition to obtain a high-white aluminum hydroxide product; or, diluting the sodium aluminate concentrate and passing in carbon dioxide for decomposition to obtain a high-white aluminum hydroxide product; The inducer comprises at least one of: aluminum hydroxide, magnesium hydroxide, zinc hydroxide, aluminum oxide, magnesium oxide, and zinc oxide; The mass ratio of the amount of the inducer added to the mass of aluminum hydroxide in the sodium aluminate solution is 0.1% to 20%; The target alumina concentration is 8 g / L to 180 g / L, and the target caustic ratio is 1.30 to 1.80; The adsorption decolorization reaction temperature is 20°C to 70°C, and the adsorption decolorization reaction time is 0.5 h to 5 h; The Bayer process aluminum hydroxide has a whiteness of 65% to 87% and a particle size of 50 μm to 120 μm; The high-white aluminum hydroxide product has a particle size d50 of 0.9 μm to 100 μm and a whiteness of ≥92%; The inducer has a particle size of 0.5 μm to 50 μm; The reslurry reaction temperature is 100°C to 150°C; The sodium aluminate solution has an alumina concentration of 150 g / L to 260 g / L and a caustic ratio of 1.30 to 1.

80.

2. The production method according to claim 1, characterized by, The mass ratio of the amount of the aluminum hydroxide seeds added to the mass of aluminum hydroxide in the sodium aluminate concentrate is 0.7% to 800%; The aluminum hydroxide seeds have a median particle size of 1.0 μm to 120 μm.

3. The preparation method according to claim 1, characterized in that, The decomposition temperature is 50°C to 75°C, the decomposition time is 10 h to 100 h, and the target aluminum hydroxide for decomposition has a median particle size of 0.9 μm to 100 μm.

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