Aluminum hydroxide dry gel and method for preparing the same

Abstract

The application relates to an aluminum hydroxide dry glue and a preparation method thereof, and belongs to the technical field of fine aluminum oxide; the method comprises the following steps: neutralizing an acid source and an alkali source to obtain reaction slurry, the pH value of the neutralization reaction process is 3-5, and the pH value of the neutralization reaction endpoint is 5-6.5; the reaction slurry is aged to obtain aluminum hydroxide dry glue; the generation and growth of aluminum hydroxide or pseudo-boehmite seeds are prevented through the mode of controlling the pH values of the neutralization reaction process and the endpoint, so that the final product is aluminum hydroxide dry glue, a new path for preparing aluminum hydroxide dry glue through a neutralization method is provided, the method has the advantages of simple process, high controllability, excellent product performance and the like, the obtained aluminum hydroxide dry glue has the characteristics of high acid solubility and low density, can be completely dissolved in aluminum sulfate or lactic acid, and the bulk density is less than or equal to 0.4 g / ml.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fine alumina, in particular to an aluminum hydroxide dry gel and a preparation method thereof. BACKGROUND

[0002] The aluminum hydroxide dry gel is a white and relatively transparent amorphous alumina hydrate colloid, which is a group of hydrated alumina products with uncertain composition and no crystalline state, and its structural formula is Al2O3·xH2O (x = 3.5-6). There is no obvious characteristic peak under x-ray irradiation. Due to its unique properties, it is widely used in medical treatment, papermaking, chemical industry, ceramics, electronic products, water treatment, concrete and other industries, especially in water treatment, and excellent adsorption performance is more and more favored. At the same time, like human "cells", it can differentiate into different products under different conditions, and amorphous aluminum hydroxide is often used as a precursor for preparing active alumina.

[0003] In the existing production process, the aluminum hydroxide dry gel is usually prepared by alcohol aluminum method and carbon separation method. The alcohol aluminum method mainly uses alcohol and metal aluminum to generate alkyl aluminum or alcohol aluminum, and then controls certain temperature, pH value and pressure and other conditions to hydrolyze the slurry after alcohol aluminum, and the product is obtained by filtering, washing, aging and drying. The product has high purity, but it is difficult to purify alcohol aluminum, and the catalyst used pollutes the environment. In addition, the process equipment requires high, resulting in high overall production cost. The carbonation method mainly uses sodium aluminate solution carbonation method. The production principle of the aluminum hydroxide dry gel is that the sodium aluminate solution is neutralized into gel by introducing CO2 under specific conditions, and then the pH is adjusted to continue the secondary reaction with acidic substances to obtain the gel. The gel is aged, washed and filtered to obtain the aluminum hydroxide dry gel. This method has incomparable advantages because it is grafted in the production process of large alumina plants, but it involves gas, liquid and solid three-phase reaction, and the degree of fine operation is high. If not careful, it will lead to low product yield and high sodium content of the product, which is not conducive to subsequent reprocessing. SUMMARY

[0004] The present application provides an aluminum hydroxide dry gel and a preparation method thereof, to provide a new preparation path of the aluminum hydroxide dry gel.

[0005] In a first aspect, the present application provides a preparation method of an aluminum hydroxide dry gel, which comprises:

[0006] The acid source and the base source are subjected to a neutralization reaction to obtain a reaction slurry, and the pH value of the neutralization reaction process is 3-5, and the pH value at the end of the neutralization reaction is 5-6.5;

[0007] The reaction slurry is aged to obtain the aluminum hydroxide dry gel.

[0008] As an optional implementation, the pH value of the neutralization reaction process is 4-5, and the pH value at the end of the neutralization reaction is 6-6.5.

[0009] As an optional implementation, the neutralization reaction is carried out at a temperature of 10-60°C.

[0010] As an optional implementation method,

[0011] The acid source includes an aluminum salt solution; and / or

[0012] The acid source includes at least one of aluminum sulfate solution, aluminum nitrate solution, and aluminum chloride solution.

[0013] As an optional implementation, the aluminum sulfate solution has an aluminum oxide concentration of 10-108 g / L; the aluminum nitrate solution has an aluminum oxide concentration of 10-200 g / L; and the aluminum chloride solution has an aluminum oxide concentration of 10-200 g / L.

[0014] As an optional implementation, the alkali source includes at least one of sodium aluminate solution and carbon mother liquor, wherein the carbon mother liquor is the carbon mother liquor from the alumina production process.

[0015] As an optional implementation, the caustic ratio α of the sodium aluminate solution... k The concentration of alumina in the sodium aluminate solution is 10-200 g / L, and the concentration of sodium carbonate in the carbon mother liquor is 40-180 g / L.

[0016] As an optional implementation, the neutralization reaction of the acid source and the alkali source to obtain the reaction slurry specifically includes:

[0017] An alkali source is introduced into an acid source to carry out a neutralization reaction, resulting in a reaction slurry; the flow rate of the alkali source is 0.001-5.0 m³ / h. 3 / h.

[0018] As an optional implementation, the neutralization reaction can be a continuous reaction or an intermittent reaction.

[0019] Secondly, this application provides an aluminum hydroxide dry adhesive, which is prepared using the method for preparing aluminum hydroxide dry adhesive described in the first aspect.

[0020] The technical solutions provided in this application have the following advantages compared with the prior art:

[0021] The method provided in this application prevents the formation and growth of aluminum hydroxide or boehmite seed crystals by controlling the pH value at the end of the neutralization reaction process, so that the final product is aluminum hydroxide dry glue. This provides a new route for preparing aluminum hydroxide dry glue by neutralization. This method has the advantages of simple process, high controllability and excellent product performance. The obtained aluminum hydroxide dry glue has high acid solubility and low density characteristics, and can be completely dissolved in aluminum sulfate or lactic acid. Its bulk density is ≤0.4g / ml. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A flowchart illustrating the method provided in the embodiments of this application;

[0025] Figure 2 A process diagram of the method provided in the embodiments of this application. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] 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.

[0028] like Figure 1 As shown in the embodiments of this application, a method for preparing aluminum hydroxide dry adhesive is provided, the method comprising:

[0029] S1. neutralizing the acid source and the base source to obtain a reaction slurry, wherein the pH value of the neutralization process is 3-5, and the pH value of the neutralization end point is 5-6.5; it should be noted that before the acid source and the base source are mixed to perform the neutralization reaction, a bottom liquid is set in the neutralization reaction environment, in other words, the operation of the neutralization reaction of the acid source and the base source is to introduce the acid source and the base source into the bottom liquid, and the two are mixed in the bottom liquid to perform the neutralization reaction; generally, the bottom liquid is acidic.

[0030] Preferably, the pH value of the neutralization process is 4-5, and the pH value of the neutralization end point is 6-6.5.

[0031] In some embodiments, the reaction temperature of the neutralization reaction is 10-60℃.

[0032] The reaction temperature is controlled to be between 10-60℃ in order to obtain a product that is quickly dissolved in lactic acid and has good solubility; if the reaction temperature is lower than 10℃, the obtained product has serious agglomeration of colloidal particles, is difficult to wash and filter, and has poor acid solubility in the final product; if the reaction temperature is higher than 60℃, the obtained product is easy to produce impurities, the quality of the final product is poor, and the acid solubility is affected.

[0033] In some embodiments, the acid source can be an aluminum source solution, and the aluminum salt solution can be selected from at least one of an aluminum sulfate solution, an aluminum nitrate solution, and an aluminum chloride solution. The base source includes at least one of a sodium meta-aluminate solution and a carbon separation mother liquor, and the carbon separation mother liquor is a carbon separation mother liquor in an alumina production process. Further, the mass concentration of alumina in the aluminum sulfate solution is 10-108g / L; the mass concentration of alumina in the aluminum chloride solution is 10-200g / L. The caustic ratio α of the sodium meta-aluminate solution is 1.25-1.7, and the mass concentration of alumina in the sodium meta-aluminate solution is 10-200g / L; the mass concentration of sodium carbonate in the carbon separation mother liquor is 40-180g / L. k

[0034] In some embodiments, the acid source and the base source are neutralized to obtain a reaction slurry, and the method specifically includes:

[0035] The base source is introduced into the acid source to perform a neutralization reaction to obtain a reaction slurry; the flow rate of the introduction of the base source is 0.001-5.0m 3 / h.

[0036] In some embodiments, the neutralization reaction is a continuous reaction or an intermittent reaction. If it is an intermittent reaction, aging is performed in the reaction kettle of the neutralization reaction; if it is a continuous reaction, the slurry in the reaction kettle of the neutralization reaction is continuously discharged when the volume reaches a certain value, and the obtained reaction slurry enters the aging process;

[0037] ​Specifically, in this embodiment, first, the bottom water is added into the neutralization reactor, heated to 10-60℃, and then at least one of aluminum salt solution such as aluminum sulfate, aluminum nitrate solution or aluminum chloride solution is added under stirring, the pH value of the bottom liquid is controlled to reach 3-5, then the sodium metaaluminate solution or carbonization mother liquor is added, the temperature of the reaction system is controlled at 10-60℃, the flow rate per hour is controlled at 0.001-5.0 m 3 / h, the whole neutralization reaction process can be intermittent reaction or continuous reaction, the end point pH is controlled at 5-6.5, and the reaction final temperature is controlled at 10-60℃.

[0038] S2. The reaction slurry is aged to obtain aluminum hydroxide dry gel.

[0039] In some embodiments, the aging temperature is 10-60℃, and the aging time is 10-200 min.

[0040] In some embodiments, after aging, the method further comprises filtering, washing and drying, the washing temperature is 10-80℃, and the washing end point is that the filter cake pH value is 6.5-7.5. The drying temperature is 80-120℃.

[0041] Specifically, in this embodiment, the reaction slurry is aged, the aging temperature is maintained at 10-60℃ for 10-200 min, then filtered, and the filter cake is washed with soft water at 10-80℃ until the washing water pH value is 6.5-7.5 to obtain amorphous aluminum hydroxide wet filter cake, which is dried at 80-120℃ and then crushed to obtain aluminum hydroxide dry gel.

[0042] By controlling the pH value of the neutralization reaction process and end point, the generation and growth of aluminum hydroxide or pseudoboehmite seed are prevented, so that the final product is aluminum hydroxide dry gel, a new path for preparing aluminum hydroxide dry gel by neutralization method is provided, and the method has the advantages of simple process, high controllability, excellent product performance, etc. The obtained aluminum hydroxide dry gel has high acid solubility and low density characteristics, and can be completely dissolved in aluminum sulfate or lactic acid, and the bulk density is ≤0.4 g / ml.

[0043] Based on the overall inventive concept, the embodiments of the present application also provide an aluminum hydroxide dry gel prepared by the preparation method of the aluminum hydroxide dry gel.

[0044] The aluminum hydroxide dry gel is prepared based on the above method, and the specific steps of the method can be referred to the above embodiments. Since the aluminum hydroxide dry gel adopts part or all of the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here.

[0045] The application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the application and not used to limit the scope of the application. The experimental methods in the following examples, if no specific conditions are noted, are generally determined according to national standards. If there is no corresponding national standard, the general international standards, conventional conditions, or the conditions suggested by the manufacturer are used.

[0046] Example 1

[0047] A preparation method of aluminum hydroxide dry gel, the method comprising:

[0048] In the neutralization reactor, 100 ml of bottom water at 10°C is added, 20 ml of aluminum sulfate solution (alumina content 40 g / L) is added under stirring, the pH value of the bottom solution is 4, and sodium metaaluminate solution (alumina content 40 g / L) is added in a flow, the temperature of the reaction system is controlled at 10°C, the solution flow is controlled at 40 ml / min, the whole neutralization reaction process is intermittent reaction, the reaction time is 70 min, the end point pH is controlled at 5.5, the reaction final temperature is controlled at 20°C, the obtained neutralization slurry is sent to the aging process; after keeping the aging temperature at 50°C for 100 min, filtration is performed, the filter cake is washed with soft water at 60°C until the pH value of the filter cake is 7, the amorphous aluminum hydroxide wet filter cake is obtained, which is then dried, crushed and packaged to obtain the product.

[0049] Example 2

[0050] A preparation method of aluminum hydroxide dry gel, the method comprising:

[0051] In the neutralization reactor, 300 ml of bottom water at 40°C is added, 15 ml of aluminum sulfate solution (alumina content 70 g / L) is added under stirring, the pH value of the bottom solution is 4, and carbonation mother liquor (sodium carbonate content 50 g / L) is added in a flow, the temperature of the reaction system is controlled at 40°C, the solution flow is controlled at 20 ml / min, the whole neutralization reaction process is intermittent reaction, the reaction time is 100 min, the end point pH is controlled at 6, the final temperature of the reaction system is controlled at 40°C, the obtained neutralization slurry is sent to the aging process; after keeping the aging temperature at 40°C for 50 min, filtration is performed, the filter cake is washed with soft water at 30°C until the pH value of the filter cake is 7, the amorphous aluminum hydroxide wet filter cake is obtained, which is then dried, crushed and packaged to obtain the product.

[0052] Example 3

[0053] A preparation method of aluminum hydroxide dry gel, the method comprising:

[0054] In the neutralization reactor, 300 ml of 60℃ bottom water was added, 10 ml of aluminum chloride solution (alumina content 100 g / L) was added under stirring, the bottom liquid pH value was 4, and the carbonization mother liquor (sodium carbonate content 70 g / L) was added in parallel flow, the reaction system temperature was always controlled at 60℃, the solution flow rate was controlled at 10 ml / min, the whole neutralization reaction process was continuous reaction, the end point pH was controlled at 6.5, the reaction system final temperature was controlled at 60℃, when the neutralization slurry reached a certain volume, the discharge began, the neutralization slurry extracted from the bottom of the system entered the aging process; after keeping the aging temperature at 60℃ for 30 minutes, filtration was carried out, the filter cake was washed with 40℃ soft water until the filter cake pH value was 7, the amorphous aluminum hydroxide wet filter cake was obtained, then drying, crushing and packaging were carried out, and the product was obtained.

[0055] Comparative Example 1

[0056] A preparation method of aluminum hydroxide dry gel, the method comprising:

[0057] In the neutralization reactor, 300 ml of 60℃ bottom water was added, 10 ml of aluminum chloride solution (alumina content 100 g / L) was added under stirring, the bottom liquid pH value was 4, and the carbonization mother liquor (sodium carbonate content 70 g / L) was added in parallel flow, the reaction system temperature was always controlled at 80℃, the solution flow rate was controlled at 10 ml / min, the whole neutralization reaction process was continuous reaction, the end point pH was controlled at 6.5, the reaction system final temperature was controlled at 80℃, when the neutralization slurry reached a certain volume, the discharge began, the neutralization slurry extracted from the bottom of the system entered the aging process; after keeping the aging temperature at 60℃ for 30 minutes, filtration was carried out, the filter cake was washed with 40℃ soft water until the filter cake pH value was 7, the amorphous aluminum hydroxide wet filter cake was obtained, then drying, crushing and packaging were carried out, and the product was obtained.

[0058] Comparative Example 2

[0059] A preparation method of aluminum hydroxide dry gel, the method comprising:

[0060] In the neutralization reactor, 300 ml of 60℃ bottom water was added, 10 ml of aluminum chloride solution (alumina content 100 g / L) was added under stirring, the bottom liquid pH value was 4, and the carbonization mother liquor (sodium carbonate content 70 g / L) was added in parallel flow, the reaction system temperature was always controlled at 5℃, the solution flow rate was controlled at 10 ml / min, the whole neutralization reaction process was continuous reaction, the end point pH was controlled at 6.5, the reaction system final temperature was controlled at 5℃, when the neutralization slurry reached a certain volume, the discharge began, the neutralization slurry extracted from the bottom of the system entered the aging process; after keeping the aging temperature at 60℃ for 30 minutes, filtration was carried out, the filter cake was washed with 40℃ soft water until the filter cake pH value was 7, the amorphous aluminum hydroxide wet filter cake was obtained, then drying, crushing and packaging were carried out, and the product was obtained.

[0061] Comparative Example 3

[0062] A preparation method of aluminum hydroxide dry gel, the method comprising:

[0063] In the neutralization reactor, 300 ml of 60°C bottom water was added, 10 ml of aluminum chloride solution (alumina content 100 g / L) was added under stirring, the bottom liquid pH value was 4, and the carbonization mother liquor (sodium carbonate content 70 g / L) was added in parallel flow, the reaction system temperature was always controlled at 60°C, the solution flow rate was controlled at 10 ml / min, the whole neutralization reaction process was continuous reaction, the end point pH was controlled at 7.5, the reaction system final temperature was controlled at 60°C, when the neutralization slurry reached a certain volume, the discharge began, the neutralization slurry extracted from the bottom of the system entered the aging process; after keeping the aging temperature at 60°C for 30 minutes, filtration was carried out, the filter cake was washed with 40°C soft water until the filter cake pH value was 7, the amorphous aluminum hydroxide wet filter cake was obtained, which was then dried, crushed and packaged to obtain the product.

[0064] Comparative Example 4

[0065] A preparation method of aluminum hydroxide dry gel, the method comprising:

[0066] In the neutralization reactor, 300 ml of 60°C bottom water was added, 10 ml of aluminum chloride solution (alumina content 100 g / L) was added under stirring, the bottom liquid pH value was 4, and the carbonization mother liquor (sodium carbonate content 70 g / L) was added in parallel flow, the reaction system temperature was always controlled at 60°C, the solution flow rate was controlled at 10 ml / min, the whole neutralization reaction process was continuous reaction, the end point pH was controlled at 4.5, the reaction system final temperature was controlled at 60°C, when the neutralization slurry reached a certain volume, the discharge began, the neutralization slurry extracted from the bottom of the system entered the aging process; after keeping the aging temperature at 60°C for 30 minutes, filtration was carried out, the filter cake was washed with 40°C soft water until the filter cake pH value was 7, the amorphous aluminum hydroxide wet filter cake was obtained, which was then dried, crushed and packaged to obtain the product.

[0067] The aluminum hydroxide dry gel provided by Examples 1-3 and Comparative Examples 1-4 was tested, and the results are shown in the following table:

[0068]

[0069] From the above table, it can be seen that the aluminum hydroxide dry gel prepared by the method provided in the application has high acid solubility and low density characteristics, and can be completely dissolved in aluminum sulfate or lactic acid, and the bulk density is ≤0.4 g / ml.

[0070] Various embodiments of the application can exist in a variety of forms; it should be understood that the description of the embodiments as being in a specific form is merely for convenience and brevity and should not be construed to limit the scope of the application; therefore, the description of a specific form should be considered to have specifically disclosed all possible sub-combinations of the described form and individual numerical values within the described range. For example, a 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 individual numbers within the described range, such as 1, 2, 3, 4, 5, and 6, regardless of the form of the range. Additionally, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integral) within the indicated range.

[0071] 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 "comprise", "include" and the like mean "including but not limited to".

[0072] 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 "comprise", "include" and the like mean "including but not limited to".

[0073] The above description is merely that of specific embodiments of the present application to enable a person skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application should not be limited to the embodiments shown herein, but should be consistent with the widest scope of the principles and novel features sought to be applied for herein.

Claims

1. A method for preparing aluminum hydroxide dry adhesive, characterized in that, The method includes: Add initial water to the neutralization reactor and heat to 10-60℃. Add an acid source, control the pH of the initial solution to 3-5, and then add an alkali source to carry out the neutralization reaction. The pH of the neutralization reaction is 4-5, the temperature is 10-60℃, and the flow rate is 0.001-5.0 m³ / h. 3 / h, the final pH is controlled at 5-6.5, and the final reaction temperature is controlled at 10-60℃; The reaction slurry is aged at 10-60℃ for 10-200 minutes and then filtered. The filter cake is washed with soft water at 10℃-80℃ until the pH of the wash water is 6.5-7.5 to obtain an amorphous aluminum hydroxide wet filter cake. After drying at 80-120℃, it is pulverized to obtain aluminum hydroxide dry gel. The acid source includes at least one of aluminum sulfate solution, aluminum nitrate solution and aluminum chloride solution; The alkaline source includes at least one of sodium aluminate solution and carbon mother liquor, wherein the carbon mother liquor is the carbon mother liquor in the alumina production process. The caustic ratio α of the sodium aluminate solution k The concentration of alumina in the sodium aluminate solution is 10-200 g / L; the concentration of sodium carbonate in the carbon mother liquor is 40-180 g / L.

2. The method for preparing aluminum hydroxide dry adhesive according to claim 1, characterized in that, The aluminum sulfate solution has an aluminum oxide concentration of 10-108 g / L; and / or The aluminum nitrate solution contains aluminum oxide with a mass concentration of 10-200 g / L; and / or The mass concentration of aluminum oxide in the aluminum chloride solution is 10-200 g / L.

3. The method for preparing aluminum hydroxide dry adhesive according to claim 1, characterized in that, The neutralization reaction can be a continuous reaction or an intermittent reaction.

4. An aluminum hydroxide dry adhesive, characterized in that, The aluminum hydroxide dry adhesive is prepared by the method for preparing aluminum hydroxide dry adhesive according to any one of claims 1 to 3.

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