Preparation method of high-purity barium carbonate

Abstract

The invention belongs to the technical field of inorganic materials, and particularly relates to a preparation method of high-purity barium carbonate. High-purity barium carbonate is prepared from a barium chloride solution and an ammonium bicarbonate solution through a coprecipitation method, a crystal form control agent is added into the barium chloride solution in advance, and a surfactant is added into the ammonium bicarbonate solution, so that an auxiliary agent is adsorbed to a potential crystal nucleus site in advance, the liquid phase interfacial tension is reduced, and the uniformity of a barium carbonate precipitation reaction is ensured; hyperbranched polycarboxylic acid and tartaric acid are compounded to form a crystal form control agent, polyacrylic acid and citric acid are compounded to form a composite dispersing system, the crystal form control agent, a surfactant and a composite dispersing agent are added, and the pH value in the reaction process is controlled, so that the prepared barium carbonate has higher purity and sphericity and narrower particle size distribution.

Description

Technical Field

[0001] This invention belongs to the field of inorganic materials technology, specifically relating to a method for preparing high-purity barium carbonate. Background Technology

[0002] High-purity barium carbonate, as a key inorganic fine chemical material, occupies an irreplaceable position in high-end manufacturing fields such as electronics, optical glass, and new energy due to its excellent chemical stability and physical properties. Its core applications include liquid crystal substrate glass, electronic ceramics, solid-state battery electrolyte precursors, and high-refractive-index optical materials. It can significantly improve the light transmittance, energy storage performance, and structural stability of downstream products, making it an important basic raw material supporting the upgrading of strategic emerging industries.

[0003] Nano-barium carbonate possesses superior properties compared to ordinary barium carbonate. With the rise of nanotechnology, nanomaterials, based on their unique structure, exhibit surface effects, quantum size effects, and small size effects. Compared to large-scale materials, nano-barium carbonate boasts advantages such as high magnetic permeability, low loss, and high saturation magnetization. Currently, the main industrial method for producing barium carbonate is the liquid-phase method, which involves reacting soluble barium salts with carbonates. This method offers advantages such as readily available raw materials, simple processes, and low production costs. However, in actual production, this method also reveals its shortcomings: the particle size of barium carbonate crystals cannot be effectively controlled, resulting in unstable quality and high levels of impurities, particularly high levels of chlorine, sodium, potassium, calcium, iron, and sulfur, which cannot meet the specific needs of the microelectronics industry. Furthermore, the particle size of nano-barium carbonate cannot be effectively controlled during the preparation process; additionally, the specific surface area of ​​the obtained nano-barium carbonate product cannot meet the requirements of today's increasingly miniaturized electronic devices.

[0004] Chinese patent application CN110002485A discloses a method for preparing high-purity barium carbonate, specifically: (1) barite is crushed into powder, then washed with alkali, acid and water, and finally dried to obtain barite powder; (2) barite powder is added to a reactor, nitrogen is introduced to replace the air in the reactor, nitrogen is continued to be introduced, the temperature is raised to 1000-2000℃, then a mixture of sulfur vapor and nitrogen is introduced into the reactor, and after reacting for a period of time, it is cooled to room temperature to obtain crude barium sulfide; (3) crude barium sulfide is dissolved in deionized water, and then filtered to obtain barium sulfide clear liquid; (4) under the conditions of 0-100℃ temperature and 0-1000r / min stirring speed, CO2 gas is introduced into the barium sulfide clear liquid or sodium carbonate solution is slowly added to carry out precipitation reaction to obtain high-purity barium carbonate. Although the barium carbonate produced by this method has a high purity (>99.5%), the barium sulfide particles sinter and agglomerate under high temperature conditions, forming blocky or large-sized aggregates. Even after dissolution and filtration processes, incompletely dispersed agglomeration nuclei may remain. During the precipitation reaction, these nuclei become crystal nucleation sites, promoting the formation of large-particle impurities. Furthermore, the process does not include dispersants, crystal nucleus inhibitors, or crystal form regulators, resulting in barium carbonate particles with a large size range, irregular morphology, and a lack of spherical control ability. Summary of the Invention

[0005] In order to solve the technical problems of uneven particle size distribution, low purity, and poor sphericity in the prior art, the purpose of this invention is to provide a method for preparing high-purity barium carbonate.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A method for preparing high-purity barium carbonate includes the following steps: S1: Dissolve high-purity barium chloride in deionized water to prepare a solution with a concentration of 0.5-1.0 mol / L, add a crystal form control agent, filter, and obtain a barium chloride solution; S2: Dissolve ammonium bicarbonate in deionized water to prepare a solution with a concentration of 0.5-1.0 mol / L, add a surfactant, filter, and obtain an ammonium bicarbonate solution; S3: Dissolve the composite dispersant in deionized water to prepare an aqueous solution with a mass percentage of 1%-5%, thus obtaining a composite dispersant solution; S4: Add deionized water to the reactor, then add the composite dispersant solution obtained in step S3. While stirring, add ammonia water to adjust the pH of the reaction system to 9.8-10.2. Raise the temperature to 25-35℃, and simultaneously add the barium chloride solution obtained in step S1 and the ammonium bicarbonate solution obtained in step S2. React for 1-2 hours, maintaining the pH of the reaction system at 9.8-10.2 during the reaction. Aging, filtration, washing, drying, cooling, and pulverizing are performed to obtain high-purity barium carbonate. The crystal form control agent is composed of hyperbranched polycarboxylic acid and tartaric acid in a mass ratio of (8-11):(3-5).

[0007] In the above scheme, adding a crystal form control agent to the barium chloride solution and a surfactant to the ammonium bicarbonate solution in advance can allow the auxiliary agent to be adsorbed onto potential crystal nucleation sites in advance, reduce the interfacial tension of the liquid phase, and ensure the uniformity of the barium carbonate precipitation reaction. Adding a composite dispersant solution to the reaction vessel before the reaction can avoid crystal agglomeration caused by excessively high local concentrations due to the direct addition of the reaction solution to the reaction vessel, ensuring uniform crystal dispersion. Using a stable pH value can inhibit the anisotropic growth of barium carbonate crystals and reduce the solubility of impurity ions, avoiding their co-precipitation. Using a crystal form control agent composed of hyperbranched polycarboxylic acid and tartaric acid can effectively inhibit the directional growth of crystals, guide the development of spherical crystals, assist in the adsorption of crystal nuclei, and optimize the smoothness of the crystal surface.

[0008] Furthermore, the preparation method of the hyperbranched polycarboxylic acid is as follows: maleic anhydride and propylene glycol are added to a reaction vessel at a molar ratio of 1:1, and the mixture is heated to 60-70℃ and reacted for 2-3 hours under nitrogen protection to obtain an active monomer. Maleic anhydride and benzoyl peroxide are then added, and the mixture is stirred for 15-20 minutes before adding ethylene glycol ethyl ether. The mixture is then heated to 80-85℃ and stirred for 6-8 hours. The mixture is then distilled under reduced pressure to obtain the hyperbranched polycarboxylic acid.

[0009] In the above scheme, maleic anhydride and propylene glycol are first esterified to obtain active monomers, which are then copolymerized to ensure the formation of hyperbranched polycarboxylic acid. The branched molecular structure can adsorb at multiple points on different crystal faces of barium carbonate crystals, precisely inhibiting the directional growth of highly active crystal faces and strongly guiding the crystals towards a low surface energy spherical structure, thus improving the particle size distribution and sphericity of barium carbonate. Furthermore, the steric hindrance of the branches formed by the hyperbranched polycarboxylic acid effectively prevents grain agglomeration, resulting in a synergistic effect with the composite dispersant.

[0010] Furthermore, in the preparation method of hyperbranched polycarboxylic acid, the mass of maleic anhydride added is 2-3 times the mass of the active monomer, the mass of benzoyl peroxide is 3%-5% of the mass of the active monomer, and the mass of ethylene glycol ethyl ether is 5-8 times the mass of the active monomer.

[0011] Furthermore, the crystal form control agent is composed of hyperbranched polycarboxylic acid and tartaric acid in a mass ratio of 9:4.

[0012] Furthermore, the amount of crystal form control agent added in step S1 is 4%-7% of the mass of the barium chloride solution.

[0013] Furthermore, in step S2, the amount of surfactant added is 0.2%-0.4% of the mass of the ammonium bicarbonate solution, and the surfactant is a nonionic surfactant.

[0014] In the above scheme, during the reaction process, the nonionic surfactant contains both lipophilic and hydrophilic groups in its molecules, which can selectively adsorb onto the highly active crystal faces of barium carbonate crystals. By reducing the surface energy of these crystal faces, it inhibits the directional growth of crystals along a fixed direction, avoiding the formation of irregular morphologies such as rods, plates, and blocks, and guiding the crystals to develop uniformly into a spherical structure with low surface energy. In addition, the nonionic surfactant can also form a flexible steric hindrance layer on the crystal surface, blocking the interaction between particles, effectively inhibiting crystal nucleus aggregation and abnormal growth, while reducing the solid-liquid interfacial tension, improving the fluidity of the reaction system, and synergistically working with the composite dispersant to further narrow the particle size distribution.

[0015] Furthermore, the surfactant is one of polysorbate, fatty acid sorbitan, and alkyl polyglycoside.

[0016] Furthermore, the composite dispersant mentioned in step S3 is composed of polyacrylic acid and citric acid in a mass ratio of (1-5):1.

[0017] In the above scheme, polyacrylic acid is used as an organic dispersant. It can form a dense steric hindrance layer on the surface of barium carbonate crystal nuclei through long molecular chains, which can block the van der Waals forces between particles and inhibit the agglomeration of small crystals. In addition, polyacrylic acid can also regulate the uniformity of crystal nucleus growth rate, inhibit the directional growth of crystals, and guide barium carbonate to develop into a spherical structure. Citric acid has both weak dispersing and chelating effects. Its carboxylic acid can be adsorbed onto the crystal surface to further optimize the dispersion interfacial tension and improve the dispersion performance of polyacrylic acid. Citric acid can also form soluble complexes with impurity ions such as calcium and magnesium in the system. After filtration and washing, the content of metal impurities in barium carbonate is reduced and the purity of barium carbonate is improved.

[0018] Furthermore, the amount of the composite dispersant solution used in step S4 is 0.4%-1% of the theoretical mass of barium carbonate.

[0019] Furthermore, the flow rates of the barium chloride solution and the ammonium bicarbonate solution in step S4 are set according to a molar ratio of barium chloride to ammonium bicarbonate of 1:(1.1-1.4).

[0020] In the above scheme, the morphology of barium carbonate is controlled by controlling the molar ratio of barium chloride and ammonium bicarbonate added to the reactor, so as to avoid the explosive homogeneous nucleation caused by barium ions and carbonate particles reaching high supersaturation in a short period of time, resulting in crystal agglomeration and affecting the purity and morphology of barium carbonate.

[0021] Compared with existing technologies, the method for preparing high-purity barium carbonate provided by this invention has the following technical advantages: (1) The present invention obtains barium carbonate with high purity, sphericity and narrow particle size distribution by adding crystal form control agent, surfactant and composite dispersant and controlling the pH value during the reaction process; (2) The present invention uses hyperbranched polycarboxylic acid and tartaric acid to form a crystal form control agent, which improves the dispersibility of barium carbonate crystals and the sphericity of barium carbonate crystals by multi-point adsorption of barium carbonate crystals and steric hindrance. (3) The present invention uses nonionic surfactants to reduce the surface energy of highly active crystal faces and guide the crystal to develop uniformly into a spherical structure with low surface energy. (4) The present invention uses polyacrylic acid and citric acid to form a composite dispersion system, which can improve the sphericity of barium carbonate crystals and also improve the purity of barium carbonate crystals. Attached Figure Description

[0022] Figure 1 This is a SEM image of the high-purity barium carbonate prepared in Example 4. Detailed Implementation

[0023] The following description, in conjunction with specific embodiments, provides further details, but the present invention is not limited to these embodiments. Those skilled in the art can make various modifications based on the fundamental principles of the present invention, but all modifications that do not depart from the fundamental principles of the present invention are within its scope.

[0024] Preparation Example 1 The preparation method of hyperbranched polycarboxylic acid is as follows: maleic anhydride and propylene glycol are added to a reaction vessel at a molar ratio of 1:1. Under nitrogen protection, the temperature is raised to 60℃ and reacted for 3 hours to obtain an active monomer. Maleic anhydride (twice the mass of the active monomer) and benzoyl peroxide (3% of the mass of the active monomer) are then added. After stirring for 15 minutes, ethylene glycol ethyl ether (five times the mass of the active monomer) is added and stirred until a homogeneous solution is formed. The temperature is raised to 80℃ and stirred for 6 hours. Ethyl glycol ethyl ether is removed by vacuum distillation at a vacuum degree of -0.08 MPa and a temperature of 70℃ to obtain hyperbranched polycarboxylic acid.

[0025] Preparation Example 2 The preparation method of hyperbranched polycarboxylic acid is as follows: maleic anhydride and propylene glycol are added to a reaction vessel at a molar ratio of 1:1. Under nitrogen protection, the temperature is raised to 70℃ and reacted for 2 hours to obtain an active monomer. Then, maleic anhydride (3 times the mass of the active monomer) and benzoyl peroxide (5% of the mass of the active monomer) are added. After stirring for 20 minutes, ethylene glycol ethyl ether (8 times the mass of the active monomer) is added and stirred until a homogeneous solution is formed. The temperature is raised to 85℃ and stirred for 8 hours. The ethylene glycol ethyl ether is removed by vacuum distillation at a vacuum degree of -0.09 MPa and a temperature of 80℃ to obtain hyperbranched polycarboxylic acid.

[0026] Preparation Example 3 The preparation method of hyperbranched polycarboxylic acid is as follows: maleic anhydride and propylene glycol are added to a reaction vessel at a molar ratio of 1:1. Under nitrogen protection, the temperature is raised to 68℃ and reacted for 2.5h to obtain an active monomer. Then, maleic anhydride (2.6 times the mass of the active monomer) and benzoyl peroxide (4% of the mass of the active monomer) are added. After stirring for 18min, ethylene glycol ethyl ether (7 times the mass of the active monomer) is added and stirred until a homogeneous solution is formed. The temperature is raised to 83℃ and stirred for 7h. The ethylene glycol ethyl ether is removed by vacuum distillation at a vacuum degree of -0.08MPa and a temperature of 75℃ to obtain hyperbranched polycarboxylic acid.

[0027] Preparation Example 4 The preparation method of hyperbranched polycarboxylic acid is as follows: maleic anhydride and propylene glycol are added to a reaction vessel at a molar ratio of 1:1. Under nitrogen protection, the temperature is raised to 68℃ and reacted for 2.8 h to obtain an active monomer. Then, maleic anhydride (2.7 times the mass of the active monomer) and benzoyl peroxide (4.2% of the mass of the active monomer) are added. After stirring for 18 min, ethylene glycol ethyl ether (7 times the mass of the active monomer) is added and stirred until a homogeneous solution is formed. The temperature is raised to 83℃ and stirred for 7.2 h. The ethylene glycol ethyl ether is removed by vacuum distillation at a vacuum degree of -0.09 MPa and a temperature of 75℃ to obtain hyperbranched polycarboxylic acid.

[0028] Example 1 A method for preparing high-purity barium carbonate includes the following steps: S1: High-purity barium chloride was dissolved in deionized water to prepare a 0.5 mol / L solution. A crystal form control agent was added, and the solution was filtered to obtain a barium chloride solution. The crystal form control agent was composed of hyperbranched polycarboxylic acid and tartaric acid in a mass ratio of 8:3. The hyperbranched polycarboxylic acid was prepared in Preparation Example 1. The amount of crystal form control agent added was 4% of the mass of the barium chloride solution. S2: Dissolve ammonium bicarbonate in deionized water to prepare a solution with a concentration of 0.5 mol / L, add a surfactant, filter, and obtain an ammonium bicarbonate solution; the amount of surfactant added is 0.2% of the mass of the ammonium bicarbonate solution, and the surfactant is polysorbate; S3: Dissolve the composite dispersant in deionized water to prepare a 1% (w / w) aqueous solution to obtain the composite dispersant solution; the composite dispersant is composed of polyacrylic acid and citric acid in a 1:1 (w / w) ratio. S4: Add deionized water to the reactor, then add the composite dispersant solution obtained in step S3. While stirring, add ammonia water to adjust the pH of the reaction system to 9.8. Raise the temperature to 25℃, and simultaneously add the barium chloride solution obtained in step S1 and the ammonium bicarbonate solution obtained in step S2. React for 1 hour, maintaining the pH of the reaction system at 9.8 during the reaction. Aging, filtering, washing the filter cake 5 times with 80℃ hot water, washing it 3 times with room temperature deionized water, drying at 300℃ for 15 hours, cooling, and pulverizing to obtain high-purity barium carbonate. The amount of composite dispersant solution used is 0.4% of the theoretical barium carbonate mass. The flow rates of barium chloride solution and ammonium bicarbonate solution are set according to a molar ratio of barium chloride to ammonium bicarbonate of 1:1.1.

[0029] Example 2 A method for preparing high-purity barium carbonate includes the following steps: S1: High-purity barium chloride was dissolved in deionized water to prepare a solution with a concentration of 1.0 mol / L. A crystal form control agent was added, and the solution was filtered to obtain a barium chloride solution. The crystal form control agent was composed of hyperbranched polycarboxylic acid and tartaric acid in a mass ratio of 11:5. The hyperbranched polycarboxylic acid was prepared by Preparation Example 2. The amount of crystal form control agent added was 7% of the mass of the barium chloride solution. S2: Dissolve ammonium bicarbonate in deionized water to prepare a solution with a concentration of 1.0 mol / L, add a surfactant, filter, and obtain an ammonium bicarbonate solution; the amount of surfactant added is 0.4% of the mass of the ammonium bicarbonate solution, and the surfactant is sorbitan fatty acid; S3: Dissolve the composite dispersant in deionized water to prepare a 5% (w / w) aqueous solution to obtain a composite dispersant solution; the composite dispersant is composed of polyacrylic acid and citric acid in a (w / w) ratio of 5:1. S4: Add deionized water to the reactor, then add the composite dispersant solution obtained in step S3. While stirring, add ammonia water to adjust the pH of the reaction system to 10.2. Raise the temperature to 35℃, and simultaneously add the barium chloride solution obtained in step S1 and the ammonium bicarbonate solution obtained in step S2. React for 2 hours, maintaining the pH of the reaction system at 10.2 during the reaction. Aging, filtration, washing the filter cake three times with 90℃ hot water, washing it five times with room temperature deionized water, drying at 500℃ for 10 hours, cooling, and pulverizing to obtain high-purity barium carbonate. The amount of composite dispersant solution used is 1% of the theoretical mass of barium carbonate. The flow rates of barium chloride solution and ammonium bicarbonate solution are set according to a molar ratio of barium chloride to ammonium bicarbonate of 1:1.4.

[0030] Example 3 A method for preparing high-purity barium carbonate includes the following steps: S1: High-purity barium chloride was dissolved in deionized water to prepare a solution with a concentration of 0.7 mol / L. A crystal form control agent was added, and the solution was filtered to obtain a barium chloride solution. The crystal form control agent was composed of hyperbranched polycarboxylic acid and tartaric acid in a mass ratio of 10:3. The hyperbranched polycarboxylic acid was prepared by Preparation Example 3. The amount of crystal form control agent added was 6% of the mass of the barium chloride solution. S2: Dissolve ammonium bicarbonate in deionized water to prepare a solution with a concentration of 0.8 mol / L, add a surfactant, filter, and obtain an ammonium bicarbonate solution; the amount of surfactant added is 0.3% of the mass of the ammonium bicarbonate solution, and the surfactant is APG0810; S3: Dissolve the composite dispersant in deionized water to prepare a 3% (w / w) aqueous solution to obtain the composite dispersant solution; the composite dispersant is composed of polyacrylic acid and citric acid in a (w / w) ratio of 2:1. S4: Add deionized water to the reactor, then add the composite dispersant solution obtained in step S3. While stirring, add ammonia water to adjust the pH of the reaction system to 10.0. Raise the temperature to 28℃, and simultaneously add the barium chloride solution obtained in step S1 and the ammonium bicarbonate solution obtained in step S2. React for 1.5 hours, maintaining the pH of the reaction system at 10.0 during the reaction. Aging, filtering, washing the filter cake four times with hot water at 85℃, then washing it four times with deionized water at room temperature, drying at 400℃ for 13 hours, cooling, and pulverizing to obtain high-purity barium carbonate. The amount of composite dispersant solution used is 0.6% of the theoretical mass of barium carbonate. The flow rates of the barium chloride solution and the ammonium bicarbonate solution are set according to a molar ratio of barium chloride to ammonium bicarbonate of 1:1.3.

[0031] Example 4 A method for preparing high-purity barium carbonate includes the following steps: S1: High-purity barium chloride was dissolved in deionized water to prepare a solution with a concentration of 0.8 mol / L. A crystal form control agent was added, and the solution was filtered to obtain a barium chloride solution. The crystal form control agent was composed of hyperbranched polycarboxylic acid and tartaric acid in a mass ratio of 9:4. The hyperbranched polycarboxylic acid was prepared by Preparation Example 4. The amount of crystal form control agent added was 6% of the mass of the barium chloride solution. S2: Dissolve ammonium bicarbonate in deionized water to prepare a solution with a concentration of 0.8 mol / L, add a surfactant, filter, and obtain an ammonium bicarbonate solution; the amount of surfactant added is 0.3% of the mass of the ammonium bicarbonate solution, and the surfactant is APG0814; S3: Dissolve the composite dispersant in deionized water to prepare an aqueous solution with a mass percentage of 1%-5%, thus obtaining a composite dispersant solution; the composite dispersant is composed of polyacrylic acid and citric acid in a mass ratio of 4:1; S4: Add deionized water to the reactor, then add the composite dispersant solution obtained in step S3. While stirring, add ammonia to adjust the pH of the reaction system to 10.1. Raise the temperature to 29℃, and simultaneously add the barium chloride solution obtained in step S1 and the ammonium bicarbonate solution obtained in step S2. React for 1.6 hours, maintaining the pH of the reaction system at 10.1 during the reaction. Aging, filtering, washing the filter cake four times with hot water at 88℃, then washing it four times with deionized water at room temperature, drying at 450℃ for 13 hours, cooling, and pulverizing to obtain high-purity barium carbonate. The amount of composite dispersant solution used is 0.8% of the theoretical mass of barium carbonate. The flow rates of the barium chloride solution and the ammonium bicarbonate solution are set according to a molar ratio of barium chloride to ammonium bicarbonate of 1:1.3.

[0032] Comparative Example 1 The preparation method of barium carbonate in this comparative example is similar to that in Example 4. The difference between this comparative example and Example 4 is that the crystal form control agent in step S1 of this comparative example is tartaric acid.

[0033] Comparative Example 2 The preparation method of barium carbonate in this comparative example is similar to that in Example 4. The difference between this comparative example and Example 4 is as follows: The preparation method of the hyperbranched polycarboxylic acid in step S1 of this comparative example is as follows: maleic anhydride and propylene glycol are added to the reactor at a molar ratio of 1:1. Under nitrogen protection, the temperature is raised to 68°C and reacted for 2.8 h to obtain the active monomer. Ethyl glycol ethyl ether (2.7 times the mass of the active monomer) and benzoyl peroxide (4.2% of the mass of the active monomer) are added. After stirring for 18 min, ethylene glycol ethyl ether (7 times the mass of the active monomer) is added and stirred until a homogeneous solution is formed. The temperature is raised to 83°C and stirred for 7.2 h. Ethyl glycol ethyl ether is removed by vacuum distillation at a vacuum degree of -0.09 MPa and a temperature of 75°C to obtain the hyperbranched polycarboxylic acid.

[0034] Comparative Example 3 The preparation method of barium carbonate in this comparative example is similar to that in Example 4. The difference between this comparative example and Example 4 is that the surfactant mentioned in step S2 of this comparative example is sodium dodecylbenzenesulfonate.

[0035] Comparative Example 4 The preparation method of barium carbonate in this comparative example is similar to that in Example 4. The difference between this comparative example and Example 4 is that the composite dispersant in step S3 is polyacrylic acid.

[0036] Comparative Example 5 The preparation method of barium carbonate in this comparative example is similar to that in Example 4. The difference between this comparative example and Example 4 is that the composite dispersant in step S3 is citric acid.

[0037] Test case Sphericity testing: The sphericity of barium carbonate prepared in Examples 1-4 and Comparative Examples 1-5 was tested using scanning electron microscopy; the scanning electron microscopy image of barium carbonate prepared in Example 4 is shown below. Figure 1 As shown.

[0038] D50 particle size test: The D50 particle size of barium carbonate prepared in Examples 1-4 and Comparative Examples 1-5 was tested according to GB / T 19077-2024.

[0039] Purity test: The purity of barium carbonate prepared in Examples 1-4 and Comparative Examples 1-5 was tested according to GB / T 1614-2021.

[0040] Specific surface area test: The specific surface area of ​​barium carbonate prepared in Examples 1-4 and Comparative Examples 1-5 was tested according to GB / T 19587-2017.

[0041] The test results are shown in Table 1.

[0042] Table 1 Performance Test Results

[0043] As shown in Table 1, the sphericity of barium carbonate prepared by this invention is 0.88-0.92, the D50 particle size is 0.42-0.46 μm, and the purity is 99.6%-99.9%. This indicates that the barium carbonate prepared by the method provided by this invention has a regular morphology, uniform particle size, and high purity, which is suitable for the assembly and electrical performance requirements of precision components, and the purity can cover most industrial-grade mid-to-high-end applications.

[0044] Depend on Figure 1 It can be seen that the high-purity barium carbonate particles obtained in Example 4 of the present invention are spherical.

[0045] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing high-purity barium carbonate, characterized in that, Includes the following steps: S1: Dissolve high-purity barium chloride in deionized water to prepare a solution with a concentration of 0.5-1.0 mol / L, add a crystal form control agent, filter, and obtain a barium chloride solution; S2: Dissolve ammonium bicarbonate in deionized water to prepare a solution with a concentration of 0.5-1.0 mol / L, add a surfactant, filter, and obtain an ammonium bicarbonate solution; S3: Dissolve the composite dispersant in deionized water to prepare an aqueous solution with a mass percentage of 1%-5%, thus obtaining a composite dispersant solution; S4: Add deionized water to the reactor, then add the composite dispersant solution obtained in step S3. While stirring, add ammonia water to adjust the pH of the reaction system to 9.8-10.

2. Raise the temperature to 25-35℃, and simultaneously add the barium chloride solution obtained in step S1 and the ammonium bicarbonate solution obtained in step S2. React for 1-2 hours, maintaining the pH of the reaction system at 9.8-10.2 during the reaction. Aging, filtration, washing, drying, and pulverization are performed to obtain high-purity barium carbonate. The crystal form control agent is composed of hyperbranched polycarboxylic acid and tartaric acid in a mass ratio of (8-11):(3-5).

2. The method for preparing high-purity barium carbonate according to claim 1, characterized in that, The preparation method of the hyperbranched polycarboxylic acid is as follows: maleic anhydride and propylene glycol are added to a reaction vessel at a molar ratio of 1:

1. Under nitrogen protection, the temperature is raised to 60-70℃ and reacted for 2-3 hours to obtain an active monomer. Maleic anhydride and benzoyl peroxide are then added, and the mixture is stirred for 15-20 minutes. Ethylene glycol ethyl ether is then added, and the temperature is raised to 80-85℃ and stirred for 6-8 hours. The mixture is then distilled under reduced pressure to obtain the hyperbranched polycarboxylic acid.

3. The method for preparing high-purity barium carbonate according to claim 2, characterized in that, In the preparation method of hyperbranched polycarboxylic acid, the mass of maleic anhydride added is 2-3 times the mass of the active monomer, the mass of benzoyl peroxide is 3%-5% of the mass of the active monomer, and the mass of ethylene glycol ethyl ether is 5-8 times the mass of the active monomer.

4. The method for preparing high-purity barium carbonate according to claim 1, characterized in that, The crystal form control agent is composed of hyperbranched polycarboxylic acid and tartaric acid in a mass ratio of 9:

4.

5. The method for preparing high-purity barium carbonate according to claim 1, characterized in that, The amount of crystal form control agent added in step S1 is 4%-7% of the mass of the barium chloride solution.

6. The method for preparing high-purity barium carbonate according to claim 1, characterized in that, The amount of surfactant added in step S2 is 0.2%-0.4% of the mass of the ammonium bicarbonate solution, and the surfactant is a nonionic surfactant.

7. The method for preparing high-purity barium carbonate according to claim 6, characterized in that, The surfactant is one of polysorbate, fatty acid sorbitan, and alkyl polyglycoside.

8. The method for preparing high-purity barium carbonate according to claim 1, characterized in that, The composite dispersant mentioned in step S3 is composed of polyacrylic acid and citric acid in a mass ratio of (1-5):

1.

9. The method for preparing high-purity barium carbonate according to claim 1, characterized in that, The amount of the composite dispersant solution used in step S4 is 0.4%-1% of the theoretical mass of barium carbonate.

10. The method for preparing high-purity barium carbonate according to claim 1, characterized in that, The flow rates of the barium chloride solution and the ammonium bicarbonate solution in step S4 are set according to a molar ratio of barium chloride to ammonium bicarbonate of 1:(1.1-1.4).

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