Novel sodium aluminate seed crystal decomposition crystallization auxiliary agent and preparation method thereof

Abstract

The invention discloses a novel sodium aluminate seed crystal decomposition crystallization auxiliary agent and a preparation method thereof, and the novel sodium aluminate seed crystal decomposition crystallization auxiliary agent comprises the following components by mass: 0.1%-1% of sorbitan oleate sodium sulfonate, 0.1%-1% of secondary alkyl sodium sulfonate, and the balance of distilled water. The preparation method comprises the following specific preparation steps: weighing sorbitan oleate sodium sulfonate and secondary alkyl sodium sulfonate according to a ratio, and putting the weighed materials into a beaker; and adding distilled water into the beaker until the total weight is 100g, stirring for 5-10 minutes, and dissolving into uniform liquid. According to the invention, the independently designed and synthesized sorbitan oleate sodium sulfonate and the anionic surfactant secondary alkyl sodium sulfonate are compounded, and the two components have a synergistic enhancement effect, so that agglomeration among aluminum hydroxide particles is effectively promoted, and the decomposition rate of a sodium aluminate solution is improved. The composition is simple, the preparation technology is simple, industrial production is easy, and the good industrial application prospect is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of producing aluminum hydroxide by the Bayer process, and particularly relates to a novel sodium aluminate seed decomposition crystallization auxiliary agent and a preparation method thereof. Background Art

[0002] Aluminum hydroxide is a very important chemical metallurgical raw material, widely used in medicine, environmental protection, materials and other fields. So far, the Bayer process for producing aluminum hydroxide has been adopted by more than 90% of domestic and foreign aluminum hydroxide production due to its simple process and low production cost. Most of the Bayer processes in my country use diaspore-type bauxite as raw material, and are produced in a one-stage control technology with a sodium aluminate solution with a high total alkalinity, a high seed coefficient and a low decomposition temperature. However, as the decomposition conditions change, the quality of the finished aluminum hydroxide product fluctuates greatly. Secondly, the organic matter in the bauxite will affect the decomposition rate and particle size during the seed decomposition process, and will also reduce the quality of aluminum hydroxide. Therefore, in order to improve the quality of aluminum hydroxide prepared by the Bayer process, a large number of studies have been carried out at home and abroad to improve the seed decomposition process of the sodium aluminate solution.

[0003] The decomposition process of sodium aluminate solution seeds is accompanied by complex physical and chemical changes. Finding chemical additives to improve the decomposition process of sodium aluminate solution seeds is the simplest and most efficient method, and it has always been one of the hot research directions. At present, most domestic manufacturers use imported crystallization aids. Secondly, foreign bauxite is mainly gibbsite, while my country's bauxite is gibbsite. Some imported crystallization aids cannot achieve the expected effect in actual production. This situation restricts the development of my country's aluminum hydroxide production enterprises. Therefore, it is urgent to develop a crystallization aid suitable for the characteristics of its own raw materials. For example, CN111017969A is a crystallization aid for the decomposition of sodium aluminate seeds and a method for preparing aluminum hydroxide. The method mixes phenolic resin, polyethylene glycol fatty acid ester, and biodiesel in a certain proportion to obtain a crystallization aid and adds it during the decomposition process of the seeds to promote the agglomeration of fine aluminum hydroxide particles, reduce the formation of product fine particles, and increase the average particle size of aluminum hydroxide. However, it failed to simultaneously strengthen the decomposition of sodium aluminate solution seeds and improve the decomposition rate of sodium aluminate solution. For example, CN10957403A discloses a special crystallization aid for an aluminum oxide plant and a preparation method thereof. The method first adds oleic acid, polyethylene glycol dioleate, alkylphenol polyoxyethylene ether, sodium secondary alkyl sulfonate, and Span 60 into a reactor, heats the temperature to 45-50°C and stirs for 20-30 minutes, then adds dimethyl silicone oil into the reactor, stirs again for 50-60 minutes and cools to room temperature to obtain the special crystallization aid for an aluminum oxide plant. The crystallization aid has strong applicability, effectively improves the agglomeration of aluminum hydroxide particles, and has a certain defoaming effect. However, there are many types of components, and large-scale production will lead to increased costs. In order to solve the problems of the single effect of the above-mentioned crystallization aid, complex components, and high production costs. Summary of the invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide a new sodium aluminate seed decomposition crystallization aid and a preparation method thereof, which can promote the agglomeration of aluminum hydroxide particles and simultaneously improve the decomposition rate of sodium aluminate solution, and the components are simple and easy to industrialize.

[0005] The technical solution adopted by the present invention is: a new type of sodium aluminate seed decomposition crystallization aid and a preparation method thereof, and the mass fraction of the formula composition is: Sorbitan oleate sodium sulfonate 0.1%~1% Sodium secondary alkyl sulfonate 0.1%~1% Distilled water balance Wherein, the structural formula of sorbitan sodium oleate sulfonate is:

[0006] The synthesis method of the sodium sorbitan oleate sulfonate is as follows: sorbitan oleate, diethylamine, tert-butyl perbenzoate and isopropanol are added to a three-necked flask in sequence; sodium bisulfite is placed in a beaker and distilled water is added, and the mixture is stirred sufficiently to be completely dissolved and then transferred to the three-necked flask; the three-necked flask is placed in an oil bath, the reaction temperature is controlled at 20-60° C., the reaction time is 15-50 hours, and the rotation speed is 250-500 r / min; after the reaction is completed, the reaction solution cooled to room temperature is filtered, dichloromethane is added to the filtrate for multiple extractions, the water-isopropanol phase is collected, and the isopropanol is removed by a rotary evaporator, and ethanol is added, and the mixture is heated and stirred overnight, and the filtrate is filtered and collected while hot, and the filtrate is evaporated to dryness, and then ethanol is added for recrystallization, and the sodium sorbitan oleate sulfonate is obtained after drying; The molar ratio of sorbitan oleate to sodium bisulfite is 1:2-7; the molar ratio of diethylamine to sorbitan oleate is 1:40-80; the added amount of tert-butyl perbenzoate is 1%-10% of the mass of sorbitan oleate; the molar ratio of sorbitan oleate to isopropanol is 1:15-20; and the mass ratio of isopropanol to distilled water is 1:1.

[0007] The sodium secondary alkyl sulfonate is an anionic surfactant with a carbon number of 12 to 16 and a molecular formula of R SO3Na (R=C12 to C16).

[0008] The sodium aluminate seed crystal decomposition crystallization aid specifically comprises the following steps: (1) Weigh sorbitan sodium oleate sulfonate and sodium secondary alkyl sulfonate in proportion into a beaker. (2) Add distilled water to a beaker to a total weight of 100 g, stir for 5-10 minutes and dissolve into a uniform liquid to obtain a new type of sodium aluminate seed decomposition crystallization aid.

[0009] The novel sodium aluminate seed decomposition crystallization aid described in the present invention has the following action mechanism: 1. Mechanism of action of sodium secondary alkyl sulfonate Sodium secondary alkyl sulfonate is an anionic surfactant that can effectively change the charge distribution on the surface of aluminum hydroxide particles, compress the double electron layer, reduce the critical crystal nucleus diameter, and facilitate the aluminate ions to approach the surface of aluminum hydroxide crystals, increase their concentration at certain active points, accelerate the precipitation of aluminum hydroxide, and thus improve the decomposition efficiency of sodium aluminate solution. 2. Mechanism of action of sorbitan sodium oleate sulfonate Sodium sorbitan oleate sulfonate has strong emulsifying, dispersing and solubilizing properties. ① Particle adhesion and bridging effect: The ether bond oxygen atoms and hydroxyl groups in sodium sorbitan oleate sulfonate can form hydrogen bonds with the surface of aluminum hydroxide, and are easily adsorbed on aluminum hydroxide particles to form a hydrophobic surface, which reduces the hydration force between aluminum hydroxide particles and can effectively increase the adhesion of small aluminum hydroxide particles; secondly, the longer carbon molecular chains in its chain segments can achieve a bridging effect, effectively enhancing the agglomeration effect. ② Increase solubility and emulsifying ability: Compared with linear sorbitan oleate, the branched sulfonic acid group contained in the present invention increases the density of the hydrophobic part at the air / water interface, produces a spatial inhibition effect on micellization, reduces the degree of micellization of sodium sorbitan oleate sulfonate, enhances its wetting properties, increases its solubility in sodium aluminate solution, and has stronger emulsifying ability. 3. Synergy As a stabilizer and dispersant, sodium sorbitan oleate sulfonate enhances the overall stability of the additive, while promoting the entire additive to be well dispersed in the sodium aluminate solution, maximizing the contact between the additive and aluminum hydroxide particles, and further improving the decomposition efficiency.

[0010] The technical points and beneficial effects of the present invention are as follows: 1. The present invention forms a sodium aluminate seed decomposition crystallization aid with synergistic effect by compounding sodium sorbitan oleate sulfonate and sodium secondary alkyl sulfonate. This compound system can effectively promote the agglomeration of aluminum hydroxide particles and significantly improve the decomposition efficiency of sodium aluminate solution. 2. The independently designed sodium sorbitan oleate sulfonate of the present invention can increase the stability of the overall auxiliary agent and promote its uniform dispersion in the sodium aluminate solution, ensuring that the auxiliary agent is fully in contact with the aluminum hydroxide particles, and further improving the decomposition effect. 3. The components of the invention are simple, the comprehensive performance is better than that of commercially available products, the preparation process is simple, it is easy to industrialize production, and has good industrial application prospects. DETAILED DESCRIPTION

[0011] In order to better understand the invention, the content of the patent of the present invention is further explained in conjunction with specific embodiments below. However, the content of the patent of the present invention is not limited to the following implementation examples. Based on the examples of the present invention, other implementation examples obtained by technicians in this field without creative work all fall within the scope of protection of the patent of the present invention.

[0012] The specific implementation steps of the present invention are as follows: (1) Preparation of sodium sorbitan oleate sulfonate: sorbitan oleate, diethylamine, tert-butyl perbenzoate and isopropanol are added to a three-necked flask in sequence; sodium bisulfite is placed in a beaker and distilled water is added, stirred thoroughly to dissolve it completely and then transferred to the three-necked flask; the three-necked flask is then placed in an oil bath, the reaction temperature is controlled at 20-60°C, the reaction time is 15-50h, and the rotation speed is 250-500r / min; after the reaction is completed, the reaction solution is cooled to room temperature and filtered, dichloromethane is added to the filtrate for multiple extractions, the water-isopropanol phase is collected and the isopropanol is removed by a rotary evaporator, ethanol is added, the mixture is heated and stirred overnight, the filtrate is filtered while hot and the filtrate is collected, the filtrate is evaporated to dryness, ethanol is added for recrystallization, and the sorbitan oleate sulfonate is obtained after drying; The molar ratio of sorbitan oleate to sodium bisulfite is 1:2-7; the molar ratio of diethylamine to sorbitan oleate is 1:40-80; the added amount of tert-butyl peroxybenzoate is 1%-10% of the mass of sorbitan oleate; the molar ratio of sorbitan oleate to isopropanol is 1:15-20; and the mass ratio of isopropanol to distilled water is 1:1. (2) Preparation of sodium aluminate seed decomposition crystallization aid: 0.1% to 1% of sodium sorbitan oleate sulfonate and 0.1% to 1% of sodium secondary alkyl sulfonate are weighed into a beaker in proportion. Distilled water is added to the beaker to a total weight of 100 g, and the mixture is stirred for 5 to 10 minutes and dissolved into a uniform liquid to obtain a new type of sodium aluminate seed decomposition crystallization aid.

[0013] Example 1 (1) Preparation of sorbitan sodium oleate sulfonate: 18.731 g (0.180 mol) of sodium bisulfite was added to a 100 mL beaker, and then 60.000 g of distilled water was added, and stirred thoroughly to dissolve it completely. According to the ratio of sorbitan oleate: sodium bisulfite = 1:3 (molar ratio), diethylamine: sorbitan oleate = 1:60 (molar ratio), the amount of tert-butyl peroxybenzoate added was 5% of the mass of sorbitan oleate, sorbitan oleate: isopropanol = 1:16.6 (molar ratio), and the mass ratio of isopropanol to distilled water was 1:1, 25.716 g of sorbitan oleate, 0.073 g of diethylamine, 1.286 g of tert-butyl peroxybenzoate and 60.000 g of isopropanol were weighed in sequence and added to a three-necked flask in sequence. Subsequently, the sodium bisulfite solution was transferred to a three-necked flask; finally, the three-necked flask was placed in a 40°C oil bath, stirred at 400 r / min for 10 min to fully mix the reaction materials, and reacted at 40°C and 400 r / min for 25 h. After the reaction is completed, the reaction solution is cooled to room temperature and filtered, dichloromethane is added to the filtrate for multiple extractions, the water-isopropanol phase is collected and the isopropanol is removed by a rotary evaporator, and then ethanol is added, heated and stirred overnight, and the filtrate is filtered and collected while hot, and the filtrate is evaporated to dryness, and then ethanol is added for recrystallization, and dried to obtain anhydrous sorbitan sodium oleate sulfonate; (2) Preparation of sodium aluminate seed decomposition crystallization aid: Weigh 0.640 g of sodium sorbitan oleate sulfonate and sodium secondary alkyl sulfonate in a proportion into a beaker (the mass ratio of sodium sorbitan oleate sulfonate to sodium secondary alkyl sulfonate is 1:1); add distilled water to the beaker to a total weight of 100 g, stir for 5-10 minutes and dissolve into a uniform liquid to obtain a new type of sodium aluminate seed decomposition crystallization aid.

[0014] Example 2 (1) The preparation process of sorbitan sodium oleate sulfonate is consistent with step (1) of the example. (2) Preparation of sodium aluminate seed decomposition crystallization aid: Weigh 0.640 g of sodium sorbitan oleate sulfonate and sodium secondary alkyl sulfonate in a proportion into a beaker (the mass ratio of sodium sorbitan oleate sulfonate to sodium secondary alkyl sulfonate is 1:2); add distilled water to the beaker to a total weight of 100 g, stir for 5-10 minutes and dissolve into a uniform liquid to obtain a new type of sodium aluminate seed decomposition crystallization aid.

[0015] Example 3 (1) The preparation process of sorbitan sodium oleate sulfonate is consistent with step (1) of the example. (2) Preparation of sodium aluminate seed decomposition crystallization aid: Weigh 0.640 g of sodium sorbitan oleate sulfonate and sodium secondary alkyl sulfonate in a proportion into a beaker (the mass ratio of sodium sorbitan oleate sulfonate to sodium secondary alkyl sulfonate is 2:1); add distilled water to the beaker to a total weight of 100 g, stir for 5-10 minutes and dissolve into a uniform liquid to obtain a new type of sodium aluminate seed decomposition crystallization aid.

[0016] Comparative Example 1 The difference between this comparative example and Example 1 is that no secondary alkyl sodium sulfonate is used in the preparation of the sodium aluminate seed decomposition crystallization aid in step (2).

[0017] Comparative Example 2 The difference between this comparative example and Example 1 is that in step (2), when preparing the sodium aluminate seed crystal decomposition crystallization aid, no sodium sorbitan oleate sulfonate is used.

[0018] Comparative Example 3 Comparative Example 3 is to replace the sodium sorbitan oleate sulfonate in step (2) of Example 1 with sodium methyl oleate sulfonate. The preparation steps of Comparative Example 3 are as follows: 0.640 g of sodium methyl oleate sulfonate and sodium secondary alkyl sulfonate are weighed into a beaker in proportion (the mass ratio of sodium methyl oleate sulfonate to sodium secondary alkyl sulfonate is 1:1); distilled water is added to the beaker to a total weight of 100 g, and the mixture is stirred for 5-10 minutes and dissolved into a uniform liquid, thereby obtaining a new type of sodium aluminate seed decomposition crystallization aid.

[0019] Comparative Example 4 Comparative Example 4 is to replace the sodium sorbitan oleate sulfonate in step (2) of Example 1 with sorbitan oleate. The preparation steps of Comparative Example 4 are as follows: 0.640 g of sorbitan oleate and sodium secondary alkyl sulfonate are weighed into a beaker in proportion (the mass ratio of sorbitan oleate to sodium secondary alkyl sulfonate is 1:1); distilled water is added to the beaker to a total weight of 100 g, and the mixture is stirred for 5-10 minutes and dissolved into a uniform liquid, thereby obtaining a new sodium aluminate seed decomposition crystallization aid.

[0020] Comparative Example 5 Commercially available products: SNF crystallization aid

[0021] Comparative Example 6 Commercially available products: Nalco crystallization aid

[0022] Comparative Example 7 This group of comparative examples is a blank group, without adding any additives.

[0023] The products prepared in Examples 1-3 and Comparative Examples 1-7 were subjected to performance tests, and the test methods were as follows: Decomposition rate test: Simulating the industrial conditions of the two-stage agglomeration stage, the sodium aluminate solution caustic ratio was 1.35, the total alkalinity (Nk )=110g / L, decomposition temperature is 75℃, decomposition time is 8h, stirring speed is 100r / min, seed coefficient (K S )=0.25, the amount of additive added is 40ppm. After the reaction is completed, the reaction mixture is filtered, and the filter cake is dried at 120°C for 24h to obtain the product aluminum hydroxide; the reaction liquid is titrated and analyzed using the "Chemical Industry Standard of the People's Republic of China HGT4518-2013" to calculate the decomposition rate, and the decomposition rate calculation formula is as follows: Where: α k1 (Caustic ratio) --- the ratio of the caustic soda to alumina content in the sodium aluminate stock solution α k0 (Caustic ratio) --- the ratio of the caustic soda to alumina content in the sodium aluminate mother liquor Sodium aluminate stock solution---the original sodium aluminate solution used in the decomposition process of sodium aluminate solution Sodium aluminate mother liquor --- the residual solution after the by-product treatment during the decomposition of sodium aluminate solution. Particle size test: LS-609 laser particle size analyzer was used to test the particle size of the sample, with D 50 and particle size distribution <45μm as reference, under the same decomposition conditions, D 50 The larger the value is and the smaller the value of aluminum hydroxide particle size distribution <45μm is, the better the aluminum hydroxide agglomeration effect is.

[0024] The decomposition rate of sodium aluminate solution and the analysis results of aluminum hydroxide particle size are shown in Table 1

[0025] Table 1 Decomposition rate (%) <![CDATA[D 50 (μm)]]> <45μm(%) Example 1 43.95％ 58.65 24.71 Example 2 43.75％ 56.57 27.55 Example 3 43.47％ 55.38 29.34 Comparative Example 1 37.22％ 53.73 31.70 Comparative Example 2 40.02％ 52.12 34.93 Comparative Example 3 41.45％ 53.59 32.12 Comparative Example 4 40.89％ 52.42 34.31 Comparative Example 5 41.27％ 52.83 33.55 Comparative Example 6 41.12％ 52.19 35.00 Comparative Example 7 39.43％ 51.96 35.20

[0026] It can be seen from Table 1 that the crystallization aids obtained in Examples 1-3 can promote the agglomeration of aluminum hydroxide particles and effectively improve the decomposition rate of the sodium aluminate solution during the decomposition of the sodium aluminate solution seeds, among which the effect of Example 1 is the most significant, and has good industrial application prospects. (1) Compared with Comparative Examples 1 and 2, the crystallization aid prepared by compounding sorbitan oleate sodium sulfonate and secondary alkyl sodium sulfonate in Example 1 increases the decomposition rate of sodium aluminate solution from 37.22% and 40.02% to 43.95%, respectively, and the aluminum hydroxide D 50 The particle size increased from 53.73μm and 52.12μm to 58.65μm, and the number of particles <45μm in the particle size distribution also decreased to a certain extent. This shows that the synergistic effect of sodium sorbitan oleate sulfonate and sodium secondary alkyl sulfonate is good and significant, and the best performance can be achieved; if any component is missing, the performance of the product will be significantly reduced. (2) Compared with Comparative Example 3, the crystallization aid prepared in Example 1 increased the decomposition rate of the sodium aluminate solution from 41.45% to 43.95%, and the aluminum hydroxide D 50 The particle size increased from 53.59μm to 58.65μm, and the number of particles <45μm in the particle size distribution decreased by 7.41%. This shows that the compounding effect of sodium sorbitan oleate sulfonate and sodium secondary alkyl sulfonate is better than that of sodium methyl oleate sulfonate and sodium secondary alkyl sulfonate, and the sorbitan in the terminal alcohol plays an important role in improving the comprehensive performance of the crystallization aid. (3) Compared with Comparative Example 4, the crystallization aid prepared in Example 1 increased the decomposition rate of the sodium aluminate solution from 40.89% to 43.95%, and the aluminum hydroxide D 50 The particle size increased from 52.42 μm to 58.65 μm, and the number of particles <45 μm in the particle size distribution decreased by 9.60%. This indicates that after the introduction of the branched sulfonic acid group, sorbitan oleate sulfonate sodium can better reduce the surface tension of the sodium aluminate solution than sorbitan oleate, has stronger emulsification properties, and the comprehensive performance of the crystallization aid is significantly improved. (4) Compared with Comparative Examples 5 and 6, the crystallization aids prepared in Examples 1-3 have better comprehensive performance than the commercially available products SN F and Nalco crystallization aids. (5) Compared with comparative example 7, i.e., the blank example, the decomposition rate of the sodium aluminate solution after using the crystallization aid of Example 1 of the present invention increased by 4.52%, and the aluminum hydroxide D 50 The particle size increased by 6.69 μm, and the number of particles smaller than 45 μm in the particle size distribution decreased by 10.49%, indicating that the crystallization aid of the present invention is helpful to improve the agglomeration effect of aluminum hydroxide particles and the decomposition rate of sodium aluminate solution.

Claims

1. A novel sodium aluminate seed decomposition crystallization aid, characterized in that: The auxiliary agent formula composition and its mass fraction are: Sorbitan oleate sodium sulfonate 0.1%~1% Sodium secondary alkyl sulfonate 0.1%~1% Distilled water balance Wherein, the structural formula of the sorbitan sodium oleate sulfonate is:

2. A novel sodium aluminate seed decomposition crystallization aid according to claim 1, characterized in that: The synthesis method of the sodium sorbitan oleate sulfonate is as follows: sorbitan oleate, diethylamine, tert-butyl perbenzoate and isopropanol are added to a three-necked flask in sequence; sodium bisulfite is placed in a beaker and distilled water is added, and the mixture is stirred sufficiently to be completely dissolved and then transferred to the three-necked flask; the three-necked flask is placed in an oil bath, the reaction temperature is controlled at 20-60° C., the reaction time is 15-50 hours, and the rotation speed is 250-500 r / min; after the reaction is completed, the reaction solution cooled to room temperature is filtered, dichloromethane is added to the filtrate for multiple extractions, the water-isopropanol phase is collected, and the isopropanol is removed by a rotary evaporator, and ethanol is added, and the mixture is heated and stirred overnight, and the filtrate is filtered and collected while hot, and the filtrate is evaporated to dryness, and then ethanol is added for recrystallization, and the sodium sorbitan oleate sulfonate is obtained after drying; The molar ratio of the sorbitan oleate to sodium bisulfite is 1:2-7; the molar ratio of the diethylamine to the sorbitan oleate is 1:40-80; the added amount of the tert-butyl perbenzoate is 1%-10% of the mass of the sorbitan oleate; the molar ratio of the sorbitan oleate to isopropanol is 1:15-20; and the mass ratio of the isopropanol to distilled water is 1:

1.

3. A novel sodium aluminate seed decomposition crystallization aid according to claim 1, characterized in that: The sodium secondary alkyl sulfonate is an anionic surfactant with a carbon number of 12 to 16 and a molecular formula of RSO3Na (R=C12 to C16).

4. A novel sodium aluminate seed decomposition crystallization aid according to claim 1, characterized in that: The auxiliary agent specifically comprises the following preparation steps: (1) Weigh sodium sorbitan sulfonate and sodium secondary alkyl sulfonate in proportion into a beaker; (2) Add distilled water to a beaker to a total weight of 100 g, stir for 5-10 minutes and dissolve into a uniform liquid to obtain a new type of sodium aluminate seed decomposition crystallization aid.

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