Pretreatment method for analysis and detection of sodium aluminate solution

Abstract

The invention relates to a pretreatment method for analysis and detection of a sodium aluminate solution, and the method comprises the following steps: a decomposition inhibitor containing a strong polar group is uniformly mixed with the sodium aluminate solution, the decomposition inhibitor can be rapidly and uniformly distributed around an Al-O group in the sodium aluminate solution, the Al-O group is combined with the strong polar group, and the decomposition inhibitor can be rapidly and uniformly distributed around the Al-O group in the sodium aluminate solution; aluminum hydroxide precipitates in the sodium aluminate solution are prevented from being generated, so that pretreatment of analysis and detection of the sodium aluminate solution is completed. According to the method, the performance of the sodium aluminate solution can still be kept unchanged within at least 15 days, and the sodium aluminate solution is not influenced by long-distance transportation, so that the integrity of a sample before analysis and detection is ensured, and the accuracy of analysis and detection and the laboratory comparison effect are improved.

Description

Technical Field

[0001] The present application relates to the technical field of analysis and detection and alumina production, and in particular to a pretreatment method for analysis and detection of sodium aluminate solution. Background Art

[0002] Sodium aluminate is an intermediate product of the Bayer process for producing alumina. It has a wide range of commercial uses in industries such as papermaking, water treatment flocculants, catalyst preparation, cement accelerators, and titanium dioxide coating. The composition analysis of sodium aluminate solution is conducive to the control of related production processes and the stabilization and improvement of product quality. However, sodium aluminate solutions have poor stability, especially solutions with low caustic ratios (the caustic ratio is the molar ratio of sodium oxide to aluminum oxide in sodium aluminate solutions). For example, a sodium aluminate solution with a caustic ratio of 1.3 will produce precipitation in tens of minutes to 1-2 hours, which is not conducive to sampling and analysis, and also affects the accuracy of the test.

[0003] Therefore, there is an urgent need for a pretreatment method for the analysis and detection of sodium aluminate solution. Summary of the invention

[0004] The present application provides a pretreatment method for analyzing and detecting a sodium aluminate solution to solve the following technical problem: how to improve the chemical composition stability of the sodium aluminate solution.

[0005] In a first aspect, the present application provides a pretreatment method for analyzing and detecting a sodium aluminate solution, the method comprising:

[0006] A decomposition inhibitor containing a strong polar group is uniformly mixed with a sodium aluminate solution. The decomposition inhibitor can be quickly and uniformly distributed around the Al-O group in the sodium aluminate solution. The Al-O group combines with the strong polar group to prevent the precipitation of aluminum hydroxide in the sodium aluminate solution, thereby improving the stability of the sodium aluminate solution.

[0007] Optionally, the molecular structure of the decomposition inhibitor does not contain the elements to be detected in the sodium aluminate solution, and the elements to be detected include potassium, sodium, calcium, magnesium, silicon, aluminum, iron, and copper.

[0008] Optionally, the molecular weight of the decomposition inhibitor is less than 1000.

[0009] Optionally, the decomposition inhibitor includes at least one of the following: dimethyl sulfoxide, hexadecyltrimethylammonium bromide, ethyl methacrylate, and polyethylene glycol.

[0010] Optionally, the decomposition inhibitor containing a strong polar group is uniformly mixed with the sodium aluminate solution, and the decomposition inhibitor can be quickly and uniformly distributed around the Al-O group in the sodium aluminate solution, and the Al-O group combines with the strong polar group to prevent the precipitation of aluminum hydroxide in the sodium aluminate solution, so as to improve the stability of the sodium aluminate solution, and the method also includes:

[0011] The decomposition inhibitor is diluted to obtain a decomposition inhibitor dilution solution.

[0012] Optionally, the dilution medium includes at least one of the following: water, ethanol, acetic acid, oxalic acid, ether, and acetone.

[0013] Optionally, the weight ratio of the decomposition inhibitor to the dilution medium is (5-40):(60-95).

[0014] Optionally, the volume ratio of the decomposition inhibitor dilution solution to the sodium aluminate solution is 1:(10-100).

[0015] Optionally, the volume ratio of the decomposition inhibitor dilution solution to the sodium aluminate solution is 1:(20-50).

[0016] Optionally, the caustic ratio of the sodium aluminate solution is 1-3.

[0017] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0018] The pretreatment method for analyzing and detecting the sodium aluminate solution provided in the embodiment of the present application includes: uniformly mixing a decomposition inhibitor containing a strong polar group with the sodium aluminate solution, wherein the decomposition inhibitor can be quickly and evenly distributed around the Al-O group in the sodium aluminate solution, and the Al-O group combines with the strong polar group to prevent the precipitation of aluminum hydroxide in the sodium aluminate solution, so as to improve the stability of the sodium aluminate solution. The decomposition inhibitor has good solubility and dispersibility, and can be quickly and evenly distributed around the Al-O group in the sodium aluminate solution; the strong polar group in the decomposition inhibitor can effectively improve the polarity of the decomposition inhibitor, and the strong polar group combines with the Al-O group in the sodium aluminate solution in the form of a chemical bond to prevent it from decomposing into highly active Al(OH)4 - ; or directly with Al(OH)4 - Combination, thus preventing Al(OH)4 -It decomposes with water to form aluminum hydroxide precipitation, thereby achieving the purpose of inhibiting decomposition and improving the chemical composition stability of the sodium aluminate solution. This method can ensure that the performance of the sodium aluminate solution remains unchanged for at least 15 days and will not be affected by long-distance transportation, thereby ensuring the integrity of the sample before analysis and testing, and improving the accuracy of analysis and testing and the effect of laboratory comparison. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0020] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0021] Figure 1 A schematic flow chart of a pretreatment method for analyzing and detecting a sodium aluminate solution provided in an embodiment of the present application. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0023] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0024] In the present application, the terms "include", "comprising", etc. mean "including but not limited to". "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or plural, respectively.

[0025] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0026] In a first aspect, the present application provides a pre-treatment method for analyzing and detecting a sodium aluminate solution. Figure 1 A schematic diagram of a pretreatment method for analyzing and detecting a sodium aluminate solution provided in an embodiment of the present application; see Figure 1 , the method comprising:

[0027] S1. Evenly mix a decomposition inhibitor containing a strong polar group with a sodium aluminate solution, wherein the decomposition inhibitor can be quickly and evenly distributed around the Al-O group in the sodium aluminate solution, and the Al-O group combines with the strong polar group to prevent the precipitation of aluminum hydroxide in the sodium aluminate solution, thereby improving the stability of the sodium aluminate solution.

[0028] In the embodiment of the present application, the decomposition inhibitor has good solubility and dispersibility, and can be quickly and evenly distributed around the Al-O group in the sodium aluminate solution; the strong polar group in the decomposition inhibitor can effectively improve the polarity of the decomposition inhibitor, and the strong polar group is combined with the Al-O group in the sodium aluminate solution in the form of a chemical bond to prevent it from decomposing into highly active Al(OH)4 - ; or directly with Al(OH)4 - Combination, thus preventing Al(OH)4 - It decomposes with water to form aluminum hydroxide precipitate, thereby achieving the purpose of inhibiting decomposition and improving the chemical composition stability of the sodium aluminate solution.

[0029] In some embodiments, the molecular structure of the decomposition inhibitor does not contain the elements to be detected in the sodium aluminate solution, and the elements to be detected include potassium, sodium, calcium, magnesium, silicon, aluminum, iron, and copper.

[0030] In the embodiment of the present application, the molecular structure of the decomposition inhibitor does not contain the elements to be measured in the sodium aluminate solution, and the elements to be measured include potassium, sodium, calcium, magnesium, silicon, aluminum, iron, and copper, thereby improving the accuracy of subsequent sodium aluminate solution detection.

[0031] In some embodiments, the decomposition inhibitor has a molecular weight of less than 1,000.

[0032] In the embodiment of the present application, the decomposition inhibitor is a small molecule organic substance, and a suitable molecular weight of the decomposition inhibitor can improve the solubility of the decomposition inhibitor. For example, the molecular weight of the decomposition inhibitor can be 900, 800, 700, etc.

[0033] In some embodiments, the decomposition inhibitor includes at least one of the following: dimethyl sulfoxide, hexadecyltrimethylammonium bromide, ethyl methacrylate, polyethylene glycol.

[0034] In the present embodiment, dimethyl sulfoxide (C2H6OS), hexadecyl trimethyl ammonium bromide (C 19 H 42 BrN), ethyl methacrylate (C7H 12 O2), polyethylene glycol (HO(CH2CH2O) n One or more of H are used as decomposition inhibitors. The substructures of these decomposition inhibitors do not contain the elements to be tested in the sodium aluminate solution, nor do they form macromolecular complexes or chelates with the elements in the sodium aluminate solution in the form of chemical bonds, which improves the accuracy of subsequent sodium aluminate solution detection and the chemical composition stability of the sodium aluminate solution. Further, dimethyl sulfoxide can be selected as a decomposition inhibitor, which is a colorless, odorless, transparent liquid at room temperature, soluble in most organic substances such as water, ethanol, acetone, and has a strong polarity.

[0035] In some embodiments, the decomposition inhibitor containing a strong polar group is uniformly mixed with the sodium aluminate solution, and the decomposition inhibitor can be quickly and uniformly distributed around the Al-O group in the sodium aluminate solution, and the Al-O group combines with the strong polar group to prevent the precipitation of aluminum hydroxide in the sodium aluminate solution, so as to improve the stability of the sodium aluminate solution, and the method also includes:

[0036] The decomposition inhibitor is diluted to obtain a decomposition inhibitor dilution solution.

[0037] In some embodiments, the diluting medium comprises at least one of the following: water, ethanol, acetic acid, oxalic acid, ether, acetone.

[0038] In some embodiments, the weight ratio of the decomposition inhibitor to the dilution medium is (5-40):(60-95).

[0039] In the embodiment of the present application, in order to improve the solubility and dispersibility of the decomposition inhibitor, the decomposition inhibitor is diluted. The diluting medium may be, but is not limited to, one of water, ethanol, acetic acid, oxalic acid, ether, acetone, etc. or a mixture thereof. At the same time, the use of a solvent or diluent can also measure the amount of decomposition inhibitor added. The weight ratio of the decomposition inhibitor to the diluting medium is limited to (5-40): (60-95) in order to facilitate the use of conventional sampling volumes (such as 1 mL or 5 mL, etc.) and samplers (such as pipettes or pipettes) to pipette the decomposition inhibitor dilution at the production site, which is easy to achieve the standardization and uniformity of the operation, while increasing the solubility and dispersibility of the decomposition inhibitor. Exemplarily, the weight ratio of the above-mentioned decomposition inhibitor to the diluting medium can be 5:95, 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:60, etc., and further, the weight ratio of the above-mentioned decomposition inhibitor to the diluting medium can be (10-30): (70-90).

[0040] In some embodiments, the volume ratio of the decomposition inhibitor dilution solution to the sodium aluminate solution is 1:(10-100).

[0041] In some embodiments, the volume ratio of the decomposition inhibitor dilution solution to the sodium aluminate solution is 1:(20-50).

[0042] In the embodiment of the present application, the volume ratio of the decomposition inhibitor dilution to the sodium aluminate solution is limited to 1:(10-100), which can ensure the effect of the decomposition inhibitor in stabilizing the sodium aluminate solution, thereby facilitating subsequent analysis and detection. Exemplarily, the volume ratio of the above-mentioned decomposition inhibitor dilution to the sodium aluminate solution can be 1:10, 1:10, 1:10, 1:10, 1:10, 1:10, 1:10, 1:10, 1:10, etc. Further, the volume ratio of the above-mentioned decomposition inhibitor dilution to the sodium aluminate solution can be 1:(20-50).

[0043] In some embodiments, the caustic ratio of the sodium aluminate solution is 1-3.

[0044] In the embodiments of the present application, the caustic ratio of the sodium aluminate solution may be 1, 1.5, 2, etc.

[0045] In summary, the pretreatment method for analysis and detection of sodium aluminate solution provided in the present application can ensure that the performance of the sodium aluminate solution does not change for at least 15 days, even under transportation conditions such as severe shaking; at the same time, the pretreatment method is simple to operate, easy to implement, and is conducive to improving the accuracy of detection.

[0046] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0047] Example 1

[0048] 800 g of water and 200 g of oxalic acid were mixed, and 150 g of dimethyl sulfoxide (DMSO) and 50 g of polyethylene glycol (PEG-400) were added thereto in sequence, and the mixture was mixed to obtain a diluted decomposition inhibitor A. Dimethyl sulfoxide was purchased from Hubei Xingfa Chemical Group Co., Ltd., and the chemical substance registration number (CAS NO.) was 67-68-5. Polyethylene glycol was purchased from Jiangsu Hai'an Petrochemical Plant, and the product number was PEG-400.

[0049] In the alumina dissolution production process, two 50 mL portions of sodium aluminate solution with a caustic ratio of 2.2 were taken and numbered Al-1 and Al-2. 1 mL of decomposition inhibitor A was added to the Al-2 solution using a pipette (the amount of decomposition inhibitor added was 0.2% calculated based on the mass of the sodium aluminate solution). After mixing, the main components of the Al-1 and Al-2 solutions were analyzed within 1 hour. After 15 days, the same component analysis was performed on the above two solutions again. The samples were numbered Al-1-15d and Al-2-15d. For the results, please refer to the component analysis of the sodium aluminate solution in Example 1 shown in Table 1.

[0050] Table 1 Composition analysis of sodium aluminate solution in Example 1, g / l

[0051] <![CDATA[Al2O3]]> <![CDATA[Na2O]]> <![CDATA[Ga2O3]]> <![CDATA[K2O]]> <![CDATA[SiO2]]> Organic Carbon <![CDATA[V2O5]]> Al-1 233.14 257.07 0.54 84.59 1.07 9.33 0.36 Al-2 234.35 256.88 0.53 84.29 1.12 9.28 0.36 Al-1-15d 13.57 176.21 0.27 68.41 0.48 8.79 0.28 Al-2-15d 232.45 255.18 0.54 84.68 1.14 9.25 0.37

[0052] After 15 days, Al-1-15d had obvious white or slightly yellow precipitate, while Al-2-15d had no significant change. From the component analysis results, it can be seen that the analysis results of the use of decomposition inhibitor A are not much different from those before use, indicating that the addition of decomposition inhibitors will not cause significant changes in the component analysis results; at the same time, the analysis results of the use of decomposition inhibitor A after 15 days did not change significantly, indicating that it effectively prevented the decomposition of the sodium aluminate solution, thereby improving the accuracy of the analysis and detection. The addition of decomposition inhibitor A can keep the sodium aluminate solution stable within 5 months without the formation of precipitation.

[0053] Example 2

[0054] 20 mL of acetic acid, 10 mL of acetone and 70 mL of water were mixed, 10 g of hexadecyltrimethylammonium bromide was added, and the mixture was mixed to obtain a diluted decomposition inhibitor B. Hexadecyltrimethylammonium bromide was purchased from Anhui Banghao Chemical Co., Ltd., CAS No.: 57-09-0.

[0055] Weigh 552g of chemically pure NaOH and fully dissolve it in 1020g of deionized water. Pour the sodium hydroxide solution into a high-pressure reactor and add 828g of metallurgical grade Al(OH)3. Set the temperature of the high-pressure reactor to 115℃ and keep it warm for 2h. After the reaction is completed, stop stirring and wait until the temperature drops to 70-80℃ to obtain a sodium aluminate solution Al-3 with a caustic ratio of 1.3. The solution is a colorless or slightly yellow transparent liquid with strong activity, and precipitation will occur in more than ten minutes.

[0056] Take 300 mL of solution Al-3, add 15 mL of decomposition inhibitor B (calculated according to the mass of sodium aluminate solution, the amount of decomposition inhibitor added is 0.3%), shake well and leave for 2 days, then shake on an oscillator for 2 hours, and repeat the above operation twice.

[0057] After 15 days, the sample solution was slightly yellowish, clear and transparent, without decomposition and precipitation or floccules, and no emulsification was observed. After sampling and analysis, the Na2O concentration in the solution was 281.02 g / L, and the Al2O3 concentration was 351.48 g / L, which was basically consistent with the theoretical value. Please refer to the component analysis of the solution of Example 2 shown in Table 2. The decomposition inhibitor can well prevent the sodium aluminate solution from decomposing and forming precipitation, thereby destroying the composition of the solution. The addition of decomposition inhibitor B can keep the sodium aluminate solution stable within 1 month without the formation of precipitation.

[0058] Table 2 Composition analysis of solution of Example 2

[0059] <![CDATA[Na2O,g / L]]> <![CDATA[Al2O3,g / L]]> Theoretical calculation value 277.25 350.62 Analyze the results 281.02 351.48

[0060] Example 3

[0061] 15 mL of ethanol, 15 mL of ether and 70 mL of water were mixed, 10 g of ethyl methacrylate was added, and the mixture was mixed to obtain a diluted decomposition inhibitor C. Ethyl methacrylate was purchased from Changzhou Guxu Chemical Co., Ltd., CAS No.: 97-63-2.

[0062] Weigh 800g of chemically pure NaOH and fully dissolve it in 2500g of deionized water. Pour the sodium hydroxide solution into a high-pressure reactor and add 550g of metallurgical grade Al(OH)3. Set the temperature of the high-pressure reactor to 115℃ and keep it warm for 2h. After the reaction is completed, stop stirring and wait until the temperature drops to 70-80℃ and the solution volume is maintained at 2300mL to obtain a sodium aluminate solution Al-4 with a caustic ratio of 2.84.

[0063] Take 300 mL of solution Al-4, add 15 mL of decomposition inhibitor C (calculated according to the mass of sodium aluminate solution, the amount of decomposition inhibitor added is 0.3%), shake well and leave for 2 days, then shake on an oscillator for 2 hours, and repeat the above operation twice.

[0064] After 28 days, the sample solution was slightly yellowish, clear and transparent, without decomposition and precipitation or floccules, and no emulsification was observed. After sampling and analysis, the Na2O concentration in the solution was 264.02 g / L, and the Al2O3 concentration was 163.48 g / L, which was basically consistent with the theoretical value. Please refer to the component analysis of the solution of Example 3 shown in Table 3. The decomposition inhibitor can well prevent the sodium aluminate solution from decomposing and forming precipitation, thereby destroying the composition of the solution. The addition of decomposition inhibitor C can keep the sodium aluminate solution stable within 3 months without the formation of precipitation.

[0065] Table 3 Composition analysis of solution of Example 3

[0066] <![CDATA[Na2O,g / L]]> <![CDATA[Al2O3,g / L]]> Theoretical calculation value 269.57 156.52 Analyze the results 264.02 163.48

[0067] Comparative Example 1

[0068] Two 300mL portions of the sodium aluminate solution Al-3 in Example 2 were measured, and 10mL of triethanolamine was added to one portion. It was observed that the Al-3 solution began to become turbid in about 2 days, and precipitation occurred after 1 day. No reagent was added to the other Al-3 solution, and it was observed that the Al-3 solution began to become turbid in about 2 hours, and flocculent precipitation was obviously observed after more than ten minutes, indicating that the solution was unstable. Compared with Example 2, it can be clearly seen that Example 2 can better solve the stability problem of the sodium aluminate solution, which is conducive to improving the accuracy of analysis and detection.

[0069] Comparative Example 2

[0070] Two 300mL portions of the sodium aluminate solution Al-4 in Example 3 were measured, and 10mL of sodium tartrate was added to one portion. It was observed that the Al-3 solution began to become turbid in about 4 days, and precipitation was produced after 2 days; the other Al-4 solution was not added with any reagent, and it was observed that the Al-3 solution began to become turbid in about 12 hours, and a white or slightly yellow precipitate was obviously observed to be produced at the bottom of the solution after 1 day. Compared with Example 3, it can be clearly seen that Example 3 can better solve the stability problem of the sodium aluminate solution, which is conducive to improving the accuracy of analysis and detection.

[0071] In summary, the pretreatment method for analysis and detection of the sodium aluminate solution provided in the present application can ensure that the performance of the sodium aluminate solution can remain unchanged for at least 15 days and will not be affected by long-distance transportation, thereby ensuring the integrity of the sample before analysis and detection, and improving the accuracy of analysis and detection and the effect of laboratory comparison.

[0072] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A pretreatment method for analyzing and detecting sodium aluminate solution, characterized in that: The method comprises: A decomposition inhibitor containing a strong polar group is uniformly mixed with a sodium aluminate solution. The decomposition inhibitor can be quickly and uniformly distributed around the Al-O group in the sodium aluminate solution. The Al-O group combines with the strong polar group to prevent the precipitation of aluminum hydroxide in the sodium aluminate solution, thereby completing the pretreatment of the sodium aluminate solution for analysis and detection.

2. The method according to claim 1, characterized in that The molecular structure of the decomposition inhibitor does not contain the elements to be detected in the sodium aluminate solution, and the elements to be detected include potassium, sodium, calcium, magnesium, silicon, aluminum, iron, and copper.

3. The method according to claim 1, characterized in that The molecular weight of the decomposition inhibitor is less than 1,000.

4. The method according to claim 1 or 3, characterized in that: The decomposition inhibitor comprises at least one of the following: dimethyl sulfoxide, hexadecyltrimethylammonium bromide, ethyl methacrylate, and polyethylene glycol.

5. The method according to claim 1, characterized in that The decomposition inhibitor containing a strong polar group is uniformly mixed with the sodium aluminate solution, and the decomposition inhibitor can be quickly and uniformly distributed around the Al-O group in the sodium aluminate solution. The Al-O group combines with the strong polar group to prevent the precipitation of aluminum hydroxide in the sodium aluminate solution, so as to improve the stability of the sodium aluminate solution. The method also includes: The decomposition inhibitor is diluted to obtain a decomposition inhibitor dilution solution.

6. The method according to claim 5, characterized in that The diluting medium includes at least one of the following: water, ethanol, acetic acid, oxalic acid, ether, and acetone.

7. The method according to claim 5 or 6, characterized in that: The weight ratio of the decomposition inhibitor to the dilution medium is (5-40):(60-95).

8. The method according to claim 5, characterized in that The volume ratio of the decomposition inhibitor dilution solution to the sodium aluminate solution is 1:(10-100).

9. The method according to claim 8, characterized in that The volume ratio of the decomposition inhibitor dilution solution to the sodium aluminate solution is 1:(20-50).

10. The method according to claim 1, characterized in that The caustic ratio of the sodium aluminate solution is 1-3.

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