A method for preparing barium hydroxide based on barium carbonate

Abstract

The present application relates to the technical field of barium hydroxide preparation, and proposes a method for preparing barium hydroxide based on barium carbonate, comprising the following steps: S1, adding a dispersing agent and a phase transfer promoter into water, stirring uniformly, then adding barium carbonate, and then ultrasonic dispersion under the condition of 65-70 DEG C to obtain a slurry; S2, adding organic amine into the slurry of step S1, adjusting the pH value to 10.8-11.5, then adding a complexing agent to remove impurities, adding alkali to adjust the pH value to 11.8-12.4, heating to 75-85 DEG C, and then putting in barium hydroxide seed to induce nucleation and precipitate barium hydroxide; S3, heat filtering the reaction product of step S2, and then washing and drying the filter cake to obtain barium hydroxide. Through the synergistic process of dispersing agent, phase transfer promoter and segmented pH control, the present application realizes the effect of efficiently preparing barium hydroxide from barium carbonate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of barium hydroxide preparation, and particularly relates to a method for preparing barium hydroxide based on barium carbonate. BACKGROUND

[0002] Barium hydroxide is an important chemical raw material, which is widely used in the fields of electronics, chemical industry, water treatment and special glass. The existing preparation routes of barium hydroxide mainly include: a 'carbonization-oxidation-hydrolysis' method taking barium sulfide as an intermediate, a 'thermal decomposition-hydrolysis' method taking barium carbonate as a raw material, and an electrolysis method. Among them, the barium carbonate conversion route has industrial attraction due to easy availability of raw materials and low cost, but there are problems such as low conversion efficiency, large energy consumption, and difficulty in controlling the introduction and migration of impurity ions (such as Sr, Ca, Fe, Si, etc.). The traditional process often relies on high-temperature calcination and high-alkalinity conditions to achieve barium carbonate activation or dissolution, resulting in incomplete crystal phase transformation, serious particle agglomeration, and limited reaction interface. In order to obtain high-purity barium hydroxide, multiple solid-liquid separation and recrystallization are required, which has a long process, complex material circulation, and is restricted by overall yield and economy.

[0003] For the demand of high-purity electronic grade or special grade barium hydroxide, ppb-ppm level control of impurity ions becomes a key bottleneck. The existing technology mostly uses chemical precipitation, ion exchange or membrane separation means, but there are difficulties in membrane material resistance in strong alkali environment, ion exchange resin regeneration efficiency and multi-stage precipitation selectivity. In addition, the surface inertness and low solubility of barium carbonate limit the conversion kinetics under mild conditions, which must be compensated by increasing temperature, prolonging reaction time or increasing mechanical energy introduction, further increasing energy consumption and amplifying equipment load and scaling risk. Therefore, how to realize high selectivity, high conversion rate and controllable purification of barium carbonate to barium hydroxide under relatively mild conditions is a difficult problem that needs to be solved at present. SUMMARY

[0004] Therefore, the present application provides a method for preparing barium hydroxide based on barium carbonate, which realizes efficient and selective conversion of barium carbonate to high-purity barium hydroxide under mild conditions.

[0005] The technical scheme of the present application is realized as follows: the present application provides a method for preparing barium hydroxide based on barium carbonate, which comprises the following steps:

[0006] S1, adding a dispersant and a phase transfer promoter into water, stirring uniformly, then adding barium carbonate, and then ultrasonic dispersion under the condition of 65-70 DEG C to obtain a slurry;

[0007] S2, adding an organic amine to the slurry of step S1 to adjust the pH value to 10.8-11.5, then adding a complexing agent to remove impurities, adding alkali to adjust the pH value to 11.8-12.4, and increasing the temperature to 75-85 DEG C, and then adding barium hydroxide seed crystals to induce nucleation and precipitation of barium hydroxide;

[0008] S3, performing heat filtration on the reaction product of step S2, and obtaining barium hydroxide after washing and drying the filter cake.

[0009] The present application activates the surface of barium carbonate particles by the synergistic effect of a phase transfer promoter and ultrasound, enhances the dissolution kinetics of the particles in weak alkaline conditions, constructs a pH buffer environment (10.8-11.5) by using an organic amine, promotes the partial dissolution of barium carbonate and the release of barium ions, removes calcium, strontium and other impurities by using a selective complexing agent, then increases the pH of the system to 11.8-12.4 to form a supersaturated barium hydroxide solution, and introduces seed crystals to induce directional nucleation and growth, thereby precipitating high-purity barium hydroxide crystals, and realizing efficient, low-energy and high-selectivity conversion from barium carbonate to barium hydroxide.

[0010] On the basis of the above technical solution, preferably, in step S1, the amounts of barium carbonate, dispersant and phase transfer promoter are 25%-35%, 0.03%-0.10% and 0.05%-0.30% of the total mass of the slurry, respectively.

[0011] On the basis of the above technical solution, preferably, the phase transfer promoter is a combination of tetradecyl sulfobetaine and 1-butyl-3-methyl imidazole acetate.

[0012] Tetradecyl sulfobetaine is an amphoteric surfactant with excellent interfacial adsorption capacity and micellar solubilization properties. The long-chain alkyl group in its molecular structure can insert into the hydrophobic microzone on the surface of barium carbonate particles, while the sulfobetaine and betaine polar heads extend into the aqueous phase, significantly reducing the solid-liquid interfacial tension, improving the wettability and dispersion stability of the slurry. Under the action of ultrasound, tetradecyl sulfobetaine can promote water molecules to penetrate into the defects of the barium carbonate crystal lattice, accelerate the surface dissociation, and increase the initial dissolution rate of Ba 2+ At the same time, its good biodegradability and low foaming property are beneficial to subsequent solid-liquid separation and mother liquor circulation, avoiding equipment scaling and operational interference.

[0013] 1-butyl-3-methylimidazolium acetate as a functional ionic liquid, not only has strong polarity to enhance the solubility of inorganic salt, but also can have weak electrostatic interaction with carbonate anion on the positive charge center of imidazole ring, which can weaken the lattice stability of BaCO3 and further promote the surface dissociation. When used in combination with tetradecyl sulfobetaine, the two form a "surfactant-ionic liquid" synergistic system: the former dominates the macro-interface activation and dispersion stability, and the latter is responsible for the micro-lattice disturbance and ion migration promotion. The synergistic effect of multiple inventions significantly improves the reaction activity of barium carbonate under mild conditions, making the dissolution process more efficient and uniform, providing a high-quality barium source for subsequent seed-induced crystallization. Both of them have good thermal stability and recyclability, supporting the construction of closed-loop process.

[0014] On the basis of the above technical scheme, preferably, the mass ratio of tetradecyl sulfobetaine and 1-butyl-3-methylimidazolium acetate is 0.8-2:1.

[0015] On the basis of the above technical scheme, preferably, the dispersant is sodium polyacrylate (3-5 kDa) or sodium polyaspartate (3-10 kDa).

[0016] Both sodium polyacrylate and sodium polyaspartate are anionic high molecular weight dispersants, which have excellent electrostatic repulsion and steric hindrance double stabilization mechanism, can effectively prevent particle secondary agglomeration and stabilize high solid content slurry. Sodium polyaspartate also has good biodegradability and environmental friendliness, while sodium polyacrylate has low cost and high stability, both of which can withstand temperatures above 80℃, suitable for medium-high temperature wet reaction system, ensuring that the slurry remains uniformly dispersed during the entire reaction process, improving mass transfer efficiency.

[0017] The dispersant and the phase transfer promoter form a "multi-scale interface regulation network": the dispersant dominates the macro-particle stability, preventing sedimentation and aggregation; the phase transfer promoter focuses on micro-interface activation, enhancing solid-liquid mass transfer. The two complement each other, avoiding the "over flocculation" or "interface shielding" problems that may be caused by a single additive. Especially under ultrasonic conditions, this composite system can achieve efficient dissociation and continuous wetting of barium carbonate particles, significantly improving the dissolution kinetics and providing a uniform and stable barium ion source for the subsequent directional crystallization of barium hydroxide.

[0018] On the basis of the above technical scheme, preferably, the organic amine is one or both of diisopropylamine and 2-amino-2-methyl-1-propanol.

[0019] On the basis of the above technical scheme, preferably, the seed is Ba(OH)2·8H2O, and the amount is 0.05%-0.20% of the mass of barium carbonate.

[0020] On the basis of the above technical scheme, preferably, the complexing agent is one or more compounds of nitrilotriacetic acid, iminodiacetic acid and trimethylethylenediamine triacetic acid.

[0021] On the basis of the above technical scheme, preferably, the amount of the complexing agent is 0.05%-0.50% of the mass of barium carbonate.

[0022] On the basis of the above technical scheme, preferably, the reaction of step S2 and the hot filtration of step S3 are carried out under nitrogen protection to prevent CO2 intrusion from causing carbonate regeneration.

[0023] The method for preparing barium hydroxide based on barium carbonate has the following beneficial effects relative to the prior art:

[0024] (1) The present application realizes the mass transfer and nucleation optimization of Ba(OH)2 from BaCO3 through the synergistic process of "dispersant + phase transfer promoter + staged pH control (first dissolution / complexation, then supersaturation and seed addition)". Compared with the existing technologies such as the traditional lime method, the present application significantly avoids the problems of high energy consumption, low conversion rate and large amount of CaCO3 waste discharge caused by the use of a large amount of lime milk, and realizes "zero solid waste" clean production. The method is carried out under mild conditions (65-85℃, normal pressure), without the need for high-temperature calcination or high-pressure reaction equipment, which greatly reduces the energy consumption and equipment corrosion risk. At the same time, through the organic amine buffer system and the crystal seed induced crystallization mechanism, the reaction path is precisely controlled, the recarbonation and impurity co-precipitation are effectively inhibited, and high-purity barium hydroxide products (purity ≥ 99.2%) are obtained, which is especially suitable for high-end fields such as electronics and optics that have strict requirements on impurity content.

[0025] (2) The present application optimizes the timing of seed addition: first promote the dissolution of barium carbonate at pH=10.8-11.5 and remove impurities with a complexing agent, then add Ba(OH)2·8H2O seed at pH=11.8-12.4 in the supersaturation region after heating, so that the seed avoids dissolution and plays a stable heterogeneous nucleation role. This strategy reduces the uncertainty of nucleation and the risk of overshoot, making the crystal morphology controllable and the batch repeatability higher, while reducing the regeneration of carbonates and the inclusion of impurities, so that the product purity and content are more easily to meet high standards; combined with inert gas and appropriate filtration / drying conditions, CO2 interference and organic residues can be further reduced, achieving higher yield and quality consistency.

[0026] (3) The operation process of the method of the present application is simple, easy to realize continuous and automatic control, and has good industrial amplification potential. The present application is not only suitable for high-purity barium carbonate raw materials, but also can be extended to the treatment of mineral resources containing barium carbonate, providing a technical path for the efficient utilization of low-grade barium ore, and has significant economic value and sustainable development significance. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0028] The barium carbonate used in the present application is self-made light barium carbonate (light No. 1), and the purity of the barium carbonate is ≥99.2%. Tetradecyl sulfobetaine (CAS: 14933-09-6) is purchased from Macklin, and 1-butyl-3-methyl imidazole acetate (CAS number 284049-75-8) is purchased from Shanghai Huayuan Biotechnology Co., Ltd.

[0029] Example 1

[0030] The method for preparing barium hydroxide based on barium carbonate comprises the following steps:

[0031] S1. Taking the preparation of 10 kg slurry as an example, the dispersant sodium polyacrylate and the phase transfer promoter (tetradecyl sulfobetaine and 1-butyl-3-methyl imidazole acetate with a mass ratio of 1:1) were added into deionized water in a sealed reaction kettle (alkali corrosion resistant material) (to prevent water evaporation and CO2 invasion), and stirred at 400 rpm until dissolved, then barium carbonate was added, then the system was heated to 68℃, and the ultrasonic (frequency 40 kHz, power 500 W) was started, while maintaining stirring (600 rpm), and the slurry was obtained by ultrasonic dispersion for 40 min;

[0032] Among them, the amount of barium carbonate, dispersant and phase transfer promoter is 30%, 0.06% and 0.15% of the total mass of the slurry (10 kg) respectively, and the rest is deionized water.

[0033] S2, under the protection of nitrogen (flow rate 0.5 L / min, continuous input), slowly add organic amine diisopropylamine to the slurry of step S1, monitor with a pH meter, adjust the pH value to 11 (rate 0.10 pH / min), and incubate and stir for 1 h to promote the dissolution of barium carbonate; then add 0.3% of the complexing agent nitrilotriacetic acid of the mass of barium carbonate, continue to stir for 30 min to make the impurity ions be complexed; then adjust the pH value to 12.0 by adding NaOH dropwise (rate 0.05 pH / min), and at the same time, heat to 80°C; under this supersaturation condition, add 0.13% of the mass of barium carbonate of barium hydroxide seed crystals (Ba(OH)2·8H2O, particle size 5-10 μm), continue to stir at 600 rpm for 1.5 h, and induce the directional nucleation and crystal growth of barium hydroxide. Nitrogen protection can effectively isolate CO2 in the air, prevent Ba(OH)2 from reacting with CO2 to generate BaCO3 re-precipitation, and ensure the purity of the product.

[0034] S3, after the reaction is completed, filter (80°C, 1-5 μm polypropylene / polyester filter cloth or metal sintered filter core) under the protection of nitrogen (80°C, 1-5 μm polypropylene / polyester filter cloth or metal sintered filter core) while hot to separate the precipitated barium hydroxide crystals. The filter cake is washed 3 times with deionized water preheated to 70°C (the amount of water used each time is 1.5 times the volume of the filter cake) to remove the surface-adsorbed organic additives and soluble salts. The washed filter cake is dried in a 80°C vacuum drying oven for 6 h to obtain white flaky or granular barium hydroxide octahydrate product.

[0035] Example 2

[0036] This example is based on the method for preparing barium hydroxide from barium carbonate, which comprises the following steps:

[0037] S1, for example, to prepare 10 kg of slurry, add dispersant polyaspartic acid sodium and phase transfer promoter (mass ratio of tetradecyl sulfobetaine and 1-butyl-3-methyl imidazole acetate 0.8:1) into deionized water in a sealed reaction kettle (alkali corrosion resistant material) (to prevent water evaporation and CO2 invasion), stir at 400 rpm until dissolved, then add barium carbonate, then heat the system to 65°C, turn on the ultrasonic (frequency 40 kHz, power 500 W), while maintaining stirring (600 rpm), ultrasonic dispersion for 40 min to obtain a slurry;

[0038] Among them, the amount of barium carbonate, dispersant, and phase transfer promoter is 25%, 0.03%, and 0.05% of the total mass of the slurry (10 kg) respectively, and the rest is deionized water.

[0039] S2, under the protection of nitrogen (flow rate 0.5 L / min, continuous input), slowly add organic amine (2-amino-2-methyl-1-propanol) to the slurry of step S1, monitor with pH meter, adjust pH to 10.8 (rate 0.10 pH / min), incubate and stir for 1 h to promote the dissolution of barium carbonate; then add 0.05% of the complexing agent (iminodiacetic acid) of the mass of barium carbonate, continue to stir for 30 min to make the impurity ions be complexed; then adjust the pH to 11.8 by adding NaOH (rate 0.05 pH / min), while heating to 75°C, under this supersaturation condition, add 0.05% of the mass of barium carbonate of barium hydroxide seed crystal (Ba(OH)2·8H2O, particle size 5-10 μm), continue to stir at 600 rpm for 1.5 h to induce the directional nucleation and crystal growth of barium hydroxide. Nitrogen protection can effectively isolate CO2 in the air, prevent Ba(OH)2 from reacting with CO2 to generate BaCO3 re-precipitation, and ensure the purity of the product.

[0040] S3, after the reaction is completed, filter (75°C, 1-5 μm polypropylene / polyester filter cloth or metal sintered filter core) under the protection of nitrogen, separate the precipitated barium hydroxide crystals. The filter cake is washed 3 times with deionized water preheated to 70°C (the amount of water used is 1.5 times the volume of the filter cake each time) to remove the surface adsorbed organic additives and soluble salts. The washed filter cake is dried in a vacuum drying oven at 80°C for 6 h to obtain white flaky or granular barium hydroxide octahydrate product.

[0041] Example 3

[0042] This example is based on the method for preparing barium hydroxide from barium carbonate, which comprises the following steps:

[0043] S1, for example, prepare 10 g of slurry, add dispersant (sodium polyacrylate and sodium polyaspartate with a mass ratio of 1:1) and phase transfer promoter (tetradecyl sulfobetaine and 1-butyl-3-methyl imidazole acetate with a mass ratio of 2:1) to deionized water in a sealed reaction kettle (alkali corrosion resistant material) (to prevent water evaporation and CO2 invasion), stir at 400 rpm until dissolved, then add barium carbonate, then heat the system to 70°C, turn on the ultrasonic (frequency 40 kHz, power 500 W), while maintaining stirring (600 rpm), ultrasonic dispersion for 40 min to obtain a slurry;

[0044] wherein the amounts of barium carbonate, dispersant and phase transfer promoter are 35%, 0.10% and 0.30% of the total mass of the slurry (10 kg) respectively, and the balance is deionized water.

[0045] S2, under the protection of nitrogen (flow rate 0.5 L / min, continuous input), slowly add organic amine (diisopropylamine and 2-amino-2-methyl-1-propanol, mass ratio 1:1) to the slurry of step S1, monitor with a pH meter, adjust the pH value to 11.5 (rate 0.10 pH / min), and incubate and stir for 1 h to promote the dissolution of barium carbonate; then add 0.50% of the complexing agent trimethylethylenediamine triacetic acid of the mass of barium carbonate and continue to stir for 30 min to complex the impurity ions; then adjust the pH value to 12.4 by adding NaOH dropwise (rate 0.05 pH / min), and at the same time, raise the temperature to 85°C; under this supersaturation condition, add 0.20% of the mass of barium hydroxide seed crystals (Ba(OH)2·8H2O, particle size 5-10 μm) of barium carbonate, and continue to stir at 600 rpm for 1.5 h to induce the directional nucleation and crystal growth of barium hydroxide. Nitrogen protection can effectively isolate CO2 in the air, prevent Ba(OH)2 from reacting with CO2 to form BaCO3 and re-precipitate, and ensure the purity of the product.

[0046] S3, after the reaction is completed, filter (85°C, 1-5 µm polypropylene / polyester filter cloth or metal sintered filter core) while hot under the protection of nitrogen, and separate the precipitated barium hydroxide crystals. Wash the filter cake with deionized water preheated to 70°C for 3 times (each time the amount of water is 1.5 times the volume of the filter cake), to remove the surface-adsorbed organic additives and soluble salts. Dry the washed filter cake in a vacuum drying oven at 80°C for 6 h to obtain white flaky or granular barium hydroxide octahydrate product.

[0047] Example 4

[0048] This example is based on a method for preparing barium hydroxide from barium carbonate, which includes the following steps:

[0049] S1, for example, to prepare 10 kg of slurry, add dispersant sodium polyacrylate and phase transfer promoter (mass ratio of tetradecyl sulfobetaine and 1-butyl-3-methyl imidazole acetate 1.5:1) to deionized water in a sealed reaction kettle (alkali corrosion resistant material) (to prevent water evaporation and CO2 invasion), stir at 400 rpm until dissolved, then add barium carbonate, then heat the system to 67°C, turn on the ultrasonic (frequency 40 kHz, power 500 W), while maintaining stirring (600 rpm), ultrasonic dispersion for 40 min to obtain a slurry;

[0050] wherein the amounts of barium carbonate, dispersant, and phase transfer promoter are 28%, 0.08%, and 0.20% of the total mass of the slurry (10 kg) respectively, and the balance is deionized water.

[0051] S2, under the protection of nitrogen (flow rate 0.5 L / min, continuously), slowly add organic amine diisopropylamine to the slurry of step S1, monitor with a pH meter, adjust the pH value to 11.3 (rate 0.10 pH / min), and incubate and stir for 1 h to promote the dissolution of barium carbonate; then add 0.10% of the complexing agent nitrilotriacetic acid of the mass of barium carbonate and continue to stir for 30 min to complex the impurity ions; then adjust the pH value to 12.2 by adding NaOH (rate 0.05 pH / min), and at the same time, increase the temperature to 83℃, under this supersaturation condition, add 0.1% of the mass of barium carbonate of barium hydroxide seed crystals (Ba(OH)2·8H2O, particle size 5-10 μm), continue to stir at 600 rpm for 1.5 h, and induce the directional nucleation and crystal growth of barium hydroxide. The protection of nitrogen can effectively isolate CO2 in the air, prevent Ba(OH)2 from reacting with CO2 to generate BaCO3 re-precipitation, and ensure the purity of the product.

[0052] S3, after the reaction is completed, filter (83℃, 1-5µm polypropylene / polyester filter cloth or metal sintered filter core) under the protection of nitrogen (83℃, 1-5µm polypropylene / polyester filter cloth or metal sintered filter core) while hot to separate the precipitated barium hydroxide crystals. Wash the filter cake with deionized water preheated to 70℃ for 3 times (each time the amount of water is 1.5 times the volume of the filter cake), to remove the surface adsorbed organic additives and soluble salts. Dry the washed filter cake in a vacuum drying oven at 80℃ for 6 h to obtain white flaky or granular barium hydroxide octahydrate product.

[0053] Comparative Example 1

[0054] Comparative Example 1 and Example 1 differ in that the phase transfer facilitator in step S1 lacks tetradecyl sulfobetaine, and deionized water is used instead. The rest is the same as Example 1.

[0055] Comparative Example 2

[0056] Comparative Example 2 and Example 1 differ in that the phase transfer facilitator in step S1 lacks 1-butyl-3-methylimidazole acetate, and deionized water is used instead. The rest is the same as Example 1.

[0057] Comparative Example 3

[0058] Comparative Example 3 and Example 1 differ in that in step S1, the mass ratio of the phase transfer facilitators tetradecyl sulfobetaine and 1-butyl-3-methylimidazole acetate is 0.3:1. The rest is the same as Example 1.

[0059] Comparative Example 4

[0060] Comparative Example 4 and Example 1 differ in that step S1 lacks a dispersant, and deionized water is used instead. The rest is the same as Example 1.

[0061] Comparative Example 5

[0062] The difference between Comparative Example 5 and Example 1 is that in step S1, the amount of phase transfer accelerator exceeds the limit, specifically: the amount of phase transfer accelerator is 1% of the total mass of the slurry.

[0063] Comparative Example 6

[0064] The difference between Comparative Example 6 and Example 1 is that in step S2, the pH is adjusted to 12.0, specifically as follows:

[0065] S2, under nitrogen protection (flow rate 0.5 L / min, continuous), slowly add the organic amine diisopropylamine to the slurry from step S1, monitor with a pH meter, adjust the pH to 12.0 (rate 0.10 pH / min), and keep the mixture warm and stirred for 1 h; then add 0.3% by weight of barium carbonate complexing agent nitrilic acid triacetic acid, and continue stirring for 30 min; simultaneously raise the temperature to 80℃, add 0.13% by weight of barium carbonate barium hydroxide seed crystals (Ba(OH)2·8H2O, particle size 5-10 μm), and continue stirring at 600 rpm for 1.5 h to induce directional nucleation and crystal growth of barium hydroxide octahydrate.

[0066] The rest of the content is the same as in Example 1.

[0067] Comparative Example 7

[0068] The difference between Comparative Example 7 and Example 1 is that nitrogen gas is not introduced into the reactor, and steps S1-S3 are not performed under nitrogen protection. All other aspects are the same as in Example 1.

[0069] The barium hydroxide prepared in the examples and comparative examples was tested, and the contents of Sr, Fe, and chloride Cl impurities were tested in accordance with the HGT 2566-2014 standard for industrial barium hydroxide.

[0070] Table 1 Yield and purity of barium hydroxide octahydrate

[0071]

[0072] As shown in Table 1, Comparative Examples 1 and 2 lacked a phase transfer promoter, resulting in insufficient dissolution of barium carbonate, poor impurity removal, and reduced yield. Comparative Example 3 suffered from an imbalanced compound ratio, leading to a weakened synergistic effect. Comparative Example 4 lacked a dispersant, resulting in severe agglomeration, significant filtration losses, and numerous impurity inclusions. Comparative Example 5 had an excessive phase transfer agent, increasing organic residues and interfering with crystallization. Comparative Example 6 achieved a one-step pH adjustment to 12.0, resulting in explosive nucleation, small crystals, and severe impurity inclusions. Comparative Example 7 lacked nitrogen protection, allowing CO2 intrusion to generate BaCO3 particles, exacerbating impurity content and reducing purity.

[0073] D50 and D90 / D10 were determined using a laser particle size analyzer (wet dispersion), and the results are shown in Table 2.

[0074] Table 2 D50 and D90 / D10 of barium hydroxide octahydrate

[0075]

[0076] Example 1 adopts seed induction + dispersant + staged pH, and the growth of barium hydroxide octahydrate crystals is sufficient and the distribution is narrow. Comparative Example 1 and 2 have single phase transfer agent, and the mass transfer efficiency is low, which leads to local supersaturation and many fine crystals. Comparative Example 3 has unbalanced ratio of phase transfer agent, and the synergistic effect is weakened, which leads to uneven crystal growth rate. Comparative Example 4 has no dispersant, which leads to serious agglomeration and increased nucleation points, and inhibits the growth of crystals. Comparative Example 5 has excessive phase transfer agent, and the crystal nucleus is wrapped by an organic film, which hinders the growth, and the distribution is wide. Comparative Example 6 has one-step pH adjustment to 12.0, which leads to burst nucleation and formation of a large number of fine crystals, and the distribution is extremely wide. Comparative Example 7 has no nitrogen protection, which causes CO2 to invade and generate BaCO3 particles, and the heterogeneous nucleation interferes with the growth of the main crystals.

[0077] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for producing barium hydroxide based on barium carbonate, characterized by, The method comprises the following steps: S1, adding dispersant and phase transfer promoter into water, stirring uniformly, then adding barium carbonate, and then ultrasonic dispersion at 65-70℃ to obtain slurry; The phase transfer promoter is a combination of tetradecyl sulfobetaine and 1-butyl-3-methyl imidazole acetate, and the mass ratio of tetradecyl sulfobetaine to 1-butyl-3-methyl imidazole acetate is 0.8-2:1; The dispersant is sodium polyacrylate or sodium polyaspartate; The use amount of barium carbonate, dispersant and phase transfer promoter is 25%-35%, 0.03%-0.10% and 0.05%-0.30% of the total mass of the slurry, respectively; S2, adding organic amine into the slurry of step S1 to adjust the pH value to 10.8-11.5, then adding complexing agent to remove impurities, adjusting the pH value to 11.8-12.4 by adding alkali, increasing the temperature to 75-85℃, and then adding barium hydroxide seed to induce nucleation and precipitate barium hydroxide; S3, performing heat filtration on the reaction product of step S2, and obtaining barium hydroxide after washing and drying the filter cake; The reaction of step S2 and the heat filtration of step S3 are performed under nitrogen protection.

2. A process for the preparation of barium hydroxide based on barium carbonate as claimed in claim 1 wherein: The organic amine is one or both of diisopropylamine and 2-amino-2-methyl-1-propanol.

3. A process for the preparation of barium hydroxide based on barium carbonate as claimed in claim 1 wherein: The seed is Ba(OH)2·8H2O, and the use amount is 0.05%-0.20% of the mass of barium carbonate.

4. A process for the preparation of barium hydroxide from barium carbonate as claimed in claim 1 wherein: The complexing agent is one or several compounds selected from the group consisting of nitrilotriacetic acid, iminodiacetic acid and trimethylethylene diamine triacetic acid.

5. A process for the preparation of barium hydroxide from barium carbonate as claimed in claim 1 wherein: The use amount of the complexing agent is 0.05%-0.50% of the mass of barium carbonate.

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