Industrial-grade barium carbonate and production method thereof

Abstract

The invention provides industrial-grade barium carbonate and a production method thereof, and relates to the technical field of barium carbonate production. The method comprises the following steps: S1, pretreating a barium sulfide crude product, performing hot filtration under the protection of inert gas, and then performing vacuum concentration and cooling to obtain a barium sulfide concentrated solution; s2, adjusting the barium sulfide concentrated solution to be alkaline, adding an antioxidant and a hydrolysis inhibitor into the barium sulfide concentrated solution under a stirring condition, and filtering through a PVDF membrane to obtain a barium sulfide solution; and S3, under the protection of inert gas, introducing carbon dioxide into the barium sulfide solution, and then carrying out desulfurization washing, vacuum filtration, drying and crushing to obtain barium carbonate. The purity of the industrial-grade barium carbonate is not lower than 99.9%, the content of chloride ions is not higher than 8 ppm, the content of sulfide is smaller than 50 ppm, the content of sulfate is smaller than 0.03%, the content of sulfite is smaller than 0.05%, and the content of iron ions is smaller than 5 ppm.

Description

Technical Field

[0001] The invention relates to the technical field of barium carbonate production, and in particular to industrial-grade barium carbonate and a production method thereof. Background Art

[0002] Barium carbonate (BaCO3) is an important inorganic chemical product, widely used in electronic ceramics, optical glass, magnetic materials, flame retardants or the production of other barium salts. The main methods for industrial production of barium carbonate include: double decomposition (reaction of barium chloride and carbonate), carbonization (reaction of barium sulfide and carbon dioxide), etc. Among them, the carbonization method has become the mainstream process for producing barium carbonate because of its easy availability of raw materials and low cost.

[0003] However, the traditional carbonization method still has some limitations in producing barium carbonate, especially in controlling product purity. This method mainly produces barium carbonate through the reaction of barium sulfide and carbon dioxide, but in actual operation it is difficult to avoid the introduction of impurities such as sulfate, iron ions, chloride ions, etc. These impurities seriously affect the purity and application performance of the product.

[0004] Therefore, there is an urgent need to develop a new method for producing industrial-grade barium carbonate to obtain barium carbonate products with higher purity to meet the demand of the high-end market for high-purity barium carbonate. Summary of the invention

[0005] In view of this, the present invention proposes a method for efficiently producing high-purity barium carbonate to reduce the content of impurities in the final product as much as possible.

[0006] In a first aspect, the present invention provides a method for producing industrial-grade barium carbonate, comprising the following steps: S1. After pre-treating the crude barium sulfide product, hot filtration is performed under the protection of inert gas, followed by concentration under reduced pressure and cooling to obtain a barium sulfide concentrate; S2, adjusting the barium sulfide concentrated solution of step S1 to alkalinity, adding an antioxidant and a hydrolysis inhibitor thereto under stirring, and filtering through a PVDF membrane to obtain a barium sulfide solution; S3. Under the protection of inert gas, carbon dioxide is introduced into the barium sulfide solution of step S2, followed by desulfurization and washing, vacuum filtration, drying and crushing to obtain barium carbonate.

[0007] In one or some possible embodiments, in step S1, the temperature of the hot filtration is 60-70° C. and the pressure is 0.05-1 MPa.

[0008] In one or some possible embodiments, in step S1, the pressure of the reduced pressure concentration is -0.08 to -0.1 MPa, and the concentration of the barium sulfide concentrate is 20 to 22%; The cooling method includes: cooling at a rate of 3 - 4 °C / min to 40 °C, and then cooling at a rate of 0.6 - 1.4 °C / min to 20 - 25 °C.

[0009] By adopting the above technical solution, it is possible to effectively avoid the local supersaturation phenomenon caused by rapid cooling, thereby preventing the precipitation of impurities. This method of dividing into stages and controlling the cooling rate is beneficial to maintaining the uniformity and stability of the solution, making the crystal structure of the generated barium carbonate more pure, reducing the mixing of impurities, and thus improving the purity and quality of the final product.

[0010] In one or some possible embodiments, in step S2, the pH value of the barium sulfide concentrated solution in step S1 is adjusted to 9.5 - 10.

[0011] By adopting the above technical solution, it helps to stabilize the barium sulfide solution and prevent it from undergoing a hydrolysis reaction to generate barium hydroxide or other by-products. This not only ensures the purity and efficiency of subsequent reactions but also avoids the decline in product quality caused by the generation of impurities. In addition, an appropriate alkaline environment is conducive to the antioxidant and hydrolysis inhibitor to exert their best performance and enhance the stability of the solution.

[0012] In one or some possible embodiments, in step S2, the antioxidant is selected from ascorbic acid and / or disodium EDTA, and the hydrolysis inhibitor is selected from thiourea and / or sodium citrate.

[0013] By adopting the above technical solution, the antioxidant can effectively scavenge oxygen free radicals in the solution, prevent the oxidation reaction of barium sulfide during the treatment process, and thus maintain its chemical stability. At the same time, the hydrolysis inhibitor can effectively inhibit the hydrolysis of barium sulfide and avoid the generation of unnecessary by-products such as barium hydroxide, ensuring the purity of the solution.

[0014] In one or some possible embodiments, in step S2, the mass ratio of the barium sulfide concentrated solution, the antioxidant, and the hydrolysis inhibitor is 1000: (0.5 - 1.0): (0.6 - 1.2).

[0015] In one or some possible embodiments, in step S2, the pore size of the PVDF membrane is 0.22 - 0.26 μm.

[0016] By adopting the above technical solution, filtering with a PVDF membrane has significant advantages compared to conventional filtering: its precise pore size of 0.22 - 0.26 μm can efficiently intercept sub-micron impurities such as colloidal silicate and BaSO4 microcrystals, making Fe 3+The removal rate of metal impurities such as... > 98%; and it has certain corrosion resistance, resistance to sulfide erosion, strong alkali resistance, and low-temperature thermal stability. It can not only meet the production temperature requirements but also provide good flux and filtration efficiency, ensuring the smoothness and economy of the production process and being suitable for large-scale industrial production needs. Actual operation data shows that the NTU value of the liquid after PVDF membrane filtration does not exceed 9, and the Fe 3+ residue < 10 ppm. The treatment capacity of a single membrane reaches 500 - 800 m 3 , and the flux can be restored by more than 95% through chemical cleaning. The service life is up to 3 months, and the comprehensive cost is lower than that of conventional filter materials that need to be frequently replaced. The use of this membrane can, on the one hand, ensure that there is no loss of the main components in the barium sulfide solution, and on the other hand, further improve the purity of the solution, reduce the impurity content in the final barium carbonate product, and improve the purity and quality of the product.

[0017] In one or some possible embodiments, in step S3, the way of introducing carbon dioxide is as follows: Introduce it at a rate of 0.3 - 0.5 L / min until the pH of the mixed solution reaches 8 - 8.5; then introduce it at a rate of 1.5 - 1.8 L / min until the pH of the mixed solution reaches 6.5 - 7.

[0018] By adopting the above technical solution, the introduction of carbon dioxide at a lower rate in the initial stage helps to gently start the reaction, avoiding local over-carbonation caused by rapid acidification and generating Ba(HCO3)2. BaCO3 crystal nuclei are generated at a low speed. As the pH value of the solution approaches the target range, increasing the introduction rate of carbon dioxide can accelerate the reaction process, ensure sufficient carbonation, and prompt the final pH value to stabilize within the ideal range, which is beneficial to obtaining high-purity barium carbonate products.

[0019] In one or some possible embodiments, in step S3, the desulfurizing agent is O3 with a volume fraction of 8 - 12%; the molar ratio of O3 to S 2- is 1.2 - 1.5:1.

[0020] By adopting the above technical solution, it ensures sufficient oxidation ability to completely remove sulfides, while avoiding resource waste and possible side reactions caused by excessive use of ozone. This not only improves the purity of the final barium carbonate product and reduces the impurity content but also reduces the production cost and enhances the environmental friendliness through optimized desulfurization conditions.

[0021] In one or some possible embodiments, in step S3, the washing method includes: First, wash with deionized water until the conductivity of the filtrate does not exceed 50 μS / cm, and then wash successively with 0.5% dilute ammonia water and ethanol with a concentration of 60 - 70%.

[0022] By adopting the above technical solutions, first, most of the water-soluble impurities and residual electrolytes can be effectively removed, ensuring the high purity of the barium carbonate product. Second, it helps to further remove the impurities adsorbed on the surface, improving the chemical stability and purity of the product. Finally, it can not only efficiently remove organic impurities and moisture, but also promote rapid drying and reduce the agglomeration phenomenon between particles.

[0023] In a second aspect, the present invention relates to industrial-grade barium carbonate prepared by the above method.

[0024] The industrial-grade barium carbonate and its production method provided by the present invention have the following beneficial effects compared with the prior art: (1) The purity of the industrial-grade barium carbonate of the present invention is not less than 99.9%, the chloride ion content does not exceed 8 ppm, the sulfide is less than 50 ppm, the sulfate content is less than 0.03%, the sulfite content is less than 0.05%, and the iron ion content is less than 5 ppm.

[0025] (2) The method for producing industrial-grade barium carbonate of the present invention is simple to operate and easy to control. It not only effectively reduces the impurity content, but also ensures the stability of production and the consistency of products, which is conducive to improving production efficiency and reducing production costs, and is suitable for large-scale production of industrial-grade barium carbonate. Detailed implementation mode

[0026] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work belong to the scope of protection of the present invention.

[0027] There are mainly three problems in the existing carbonization method for producing barium carbonate: First, the reduction of barite raw materials is insufficient, resulting in a low conversion rate of barium sulfide (usually only 85%-90%); second, during the carbonization process, the industrial barium sulfide solution often contains residual by-products, such as FeS, etc., which are extremely easy to co-precipitate or form inclusions with CO3 2- during the carbonization process, introducing impurities such as Fe into the final product; third, the product purity is limited by the purity of industrial carbon dioxide (usually 99.5%).

[0028] The method for preparing industrial-grade barium carbonate provided by the present invention can fundamentally improve the purity of the reactant barium sulfide. During the preparation process, first, through a series of fine control steps, including pretreatment, hot filtration and vacuum concentration under inert gas protection, precisely adjusting the pH value and adding antioxidants and hydrolysis inhibitors, and finally using a PVDF membrane for precision filtration and other process measures, impurities and insolubles in the barium sulfide solution can be effectively removed to ensure its high purity and high stability state. These measures not only significantly reduce the content of impurities such as thiosulfates, chloride ions, and metal ions in barium sulfide, but also greatly improve the overall purity of the barium sulfide solution. Secondly, through the precise control of the carbon dioxide feeding rate and the adoption of an efficient desulfurization washing technology, the resulting barium carbonate has extremely high purity and low impurity levels. The purity of the barium sulfide solution prepared by the method of the present invention can be as high as over 99.85%, and the purity of the finally obtained barium carbonate product is not less than 99.90%, and the contents of key impurities such as chloride ions, sulfides, sulfates, sulfites, and iron ions are maintained at a very low level.

[0029] The technical solution of the present invention will be further described in combination with specific embodiments.

[0030] In the present invention, the crude barium sulfide can be prepared by reacting barium salts with sulfides, can be prepared by the thermal reduction method of barite, can be extracted from barium-containing fertilizer waste, or can be directly obtained commercially.

[0031] In the present invention, the pretreatment of the crude barium sulfide includes pickling, washing with water, and crushing in sequence. The pickling step aims to remove oxide impurities on the surface of barium sulfide to ensure the purity of subsequent reactions; washing with water is used to adjust the barium sulfide product to neutral to eliminate the influence of acidic substances that may remain after pickling on subsequent processes; finally, crushing is carried out to increase the dissolution contact area of barium sulfide, thereby improving its dispersibility and reactivity in the solution. The specific materials and methods used in this process are not strictly limited, and suitable operating methods can be flexibly selected as long as the above purposes can be achieved. In the embodiments of the present invention, the inventor preferably pre-treats in the following way: first, wash the barium sulfide solid with 5% hydrochloric acid to remove surface oxides and dissolve basic impurities (such as Na2S, K2S), then rinse with deionized water until the wash water is neutral (pH value is 6 - 7), and finally crush and screen it to obtain barium sulfide powder with a particle size of 80 - 100 mesh.

[0032] In the present invention, the PVDF membrane needs to be pre-rinsed with 95% ethanol and aged under hydrothermal conditions at 60°C.

[0033] Example 1 This example provides a production method of industrial-grade barium carbonate, including the following steps: S1. After pre-treating the crude barium sulfide, under the protection of nitrogen (purity ≥ 99.99%), dissolve barium sulfide powder and thiourea accounting for 0.1% of the mass of barium sulfide powder in hot water at 60 °C. Filter while it is hot under a pressure of 0.06 MPa to remove insoluble impurities (such as silicate, unreacted barium sulfate). Then, under a pressure of -0.08 MPa, concentrate under reduced pressure. Cool to 40 °C at a rate of 3 °C / min, keep the temperature constant for 15 min, and then cool to 25 °C at a rate of 0.8 °C / min to obtain a barium sulfide concentrate with a concentration of 20%. S2. Adjust the barium sulfide concentrate obtained in step S1 to a pH value of 9.5 with a 10% sodium hydroxide solution. Under stirring conditions, dissolve disodium EDTA accounting for 0.05% of the barium sulfide concentrate (that is, add 0.5 kg per 1000 kg of concentrate, the same in the following examples and comparative examples, no further explanation), and thiourea accounting for 0.1% of the barium sulfide concentrate (that is, add 1.0 kg per 1000 kg, the same in the following examples and comparative examples, no further explanation) in hot water at 60 °C. After complete dissolution, add it to the barium sulfide concentrate, and filter through a 0.26 μm PVDF membrane to obtain a barium sulfide solution. Detect the barium sulfide solution prepared in step S2. The purity of the barium sulfide solution is not less than 99.82%, the water-insoluble matter does not exceed 1 ppm, the chloride ion content does not exceed 38 ppm, the thiosulfate content is about 0.07%, Fe 3+ / Ca 2+ and other metal ion contents < 10 ppm, NTU < 8.2.

[0034] S3. Under a nitrogen atmosphere, pass CO2 into the barium sulfide solution obtained in step S2 at a rate of 0.3 L / min until the pH of the mixed solution is 8, and then pass CO2 at a rate of 1.5 L / min until the pH of the mixed solution is 6.5. Subsequently, add ozone with a molar ratio of 1.4 times that of S 2- and a volume fraction of 8% for desulfurization. Then wash with deionized water until the conductivity of the filtrate does not exceed 50 μS / cm, and then wash successively with 0.5% dilute ammonia water and ethanol with a concentration of 70%. Filter under vacuum and dry and crush to obtain barium carbonate.

[0035] According to the relevant detection standards of industrial barium carbonate GB / T 1614-2021, detect the product. The results are as follows: the purity of barium carbonate is not less than 99.92%, the chloride ion content does not exceed 8 ppm, the sulfide content is about 13 ppm, the sulfate content is about 0.018%, the sulfite is about 0.0027%, and the iron ion is about 3 ppm.

[0036] Example 2 This example provides a production method of industrial-grade barium carbonate, including the following steps: S1. After pre-treating the crude barium sulfide, under the protection of nitrogen (purity ≥ 99.99%), dissolve barium sulfide powder and 0.1% (by mass of barium sulfide powder) of thiourea in hot water at 70 °C, filter while it is hot under a pressure of 1 MPa to remove insoluble impurities (such as silicates, unreacted barium sulfate), then under a pressure of -0.1 MPa, concentrate under reduced pressure, cool at a rate of 5 °C / min to 35 °C, keep the temperature constant for 15 min, and then cool at a rate of 1 °C / min to 20 °C to obtain a barium sulfide concentrate with a concentration of 22%. S2. Adjust the barium sulfide concentrate obtained in step S1 to a pH value of 10 with a 10% sodium hydroxide solution. Under stirring conditions, sequentially add a 0.1% ascorbic acid solution and a 0.6% thiourea solution to the barium sulfide concentrate, and after filtering through a 0.22 μm PVDF membrane, obtain a barium sulfide solution. Detect the barium sulfide solution prepared in step S2. The purity of the barium sulfide solution is not less than 99.85%, the water-insoluble matter does not exceed 1 ppm, the chloride ion content does not exceed 40 ppm, the thiosulfate content is about 0.07%, and the content of metal ions such as Fe 3+ / Ca 2+ is less than 10 ppm, and NTU < 8.5.

[0037] S3. Under a nitrogen atmosphere, pass CO2 into the barium sulfide solution in step S2 at a rate of 0.5 L / min until the pH of the mixed solution is 8.5, then pass CO2 at a rate of 1.8 L / min until the pH of the mixed solution is 7, and then add S 2- 1.5 times the molar ratio of ozone with a volume fraction of 12% for desulfurization, then wash with deionized water until the conductivity of the filtrate does not exceed 50 μS / cm, and then wash successively with 0.5% dilute ammonia water and ethanol with a concentration of 60%, filter under vacuum, dry and pulverize to obtain barium carbonate.

[0038] According to the relevant detection standards of industrial barium carbonate in GB / T 1614-2021, detect the product. The results are as follows: the purity of barium carbonate is not less than 99.92%, the chloride ion content does not exceed 8 ppm, the sulfide content is about 15 ppm, the sulfate content is about 0.020%, the sulfite is about 0.003%, and the iron ion is about 4 ppm.

[0039] Example 3 This example provides a method for producing industrial-grade barium carbonate, including the following steps: S1. After pre-treating the crude barium sulfide, under the protection of nitrogen (purity ≥ 99.99%), dissolve the barium sulfide powder and 0.1% by mass of thiourea based on the barium sulfide powder in hot water at 65 °C, filter while it is hot under a pressure of 1 MPa to remove insoluble impurities (such as silicate, unreacted barium sulfate), then under a pressure of -0.1 MPa, carry out vacuum concentration, cool at a rate of 5 °C / min to 35 °C, keep the temperature constant for 15 min, and then cool at a rate of 1 °C / min to 20 °C to obtain a barium sulfide concentrated solution with a concentration of 21%; S2. Adjust the barium sulfide concentrated solution in step S1 to a pH value of 10 with 10% sodium hydroxide solution. Under the condition of stirring, sequentially add 0.1% EDTA disodium solution and 0.6% thiourea solution to the barium sulfide concentrated solution, and filter through a 0.22 μm PVDF membrane to obtain a barium sulfide solution; Detect the barium sulfide solution prepared in step S2. The purity of the barium sulfide solution is not less than 99.83%, the water-insoluble matter does not exceed 1 ppm, the chloride ion content does not exceed 42 ppm, the thiosulfate content is about 0.075%, Fe 3+ / Ca 2+ and other metal ion contents < 11 ppm, NTU < 8.7.

[0040] S3. Under a nitrogen atmosphere, pass CO2 into the barium sulfide solution in step S2 at a rate of 0.5 L / min until the pH of the mixed solution is 8.5, then pass CO2 at a rate of 1.8 L / min until the pH of the mixed solution is 7, and then add S 2- 1.5 times the molar ratio of ozone with a volume fraction of 10% for desulfurization, then wash with deionized water until the conductivity of the filtrate does not exceed 50 μS / cm, and then wash successively with 0.5% dilute ammonia water and ethanol with a concentration of 60%, filter under vacuum, dry and crush to obtain barium carbonate.

[0041] According to the relevant detection standards of GB / T 1614-2021 industrial barium carbonate, detect the product. The results are as follows: the purity of barium carbonate is not less than 99.91%, the chloride ion content does not exceed 8 ppm, the sulfide content is about 14 ppm, the sulfate content is about 0.019%, the sulfite is about 0.0028%, and the iron ion is about 3.5 ppm.

[0042] Example 4 This example provides a production method of industrial-grade barium carbonate, including the following steps: S1. After pre-treating the crude barium sulfide, under the protection of nitrogen (purity ≥ 99.99%), dissolve barium sulfide powder and thiourea accounting for 0.1% of the mass of barium sulfide powder in hot water at 65 °C. Filter while it is hot under a pressure of 0.07 MPa to remove insoluble impurities (such as silicate, unreacted barium sulfate). Then, under a pressure of -0.1 MPa, concentrate under reduced pressure. Cool to 35 °C at a rate of 4 °C / min, keep the temperature constant for 15 min, and then cool to 20 °C at a rate of 0.7 °C / min to obtain a barium sulfide concentrate with a concentration of 21%. S2. Adjust the barium sulfide concentrate in step S1 to a pH value of 10 using a 10% sodium hydroxide solution. Under stirring conditions, sequentially add a 0.06% ascorbic acid solution and a 0.09% sodium citrate solution to the barium sulfide concentrate. After filtering through a 0.25 μm PVDF membrane, obtain a barium sulfide solution. Detect the barium sulfide solution prepared in step S2. The purity of the barium sulfide solution is not less than 99.83%, the water-insoluble matter does not exceed 1 ppm, the chloride ion content does not exceed 40 ppm, the thiosulfate content is about 0.07%, Fe 3+ / Ca 2+ The content of metal ions such as is < 10 ppm, and NTU < 8.5.

[0043] S3. Under a nitrogen atmosphere, introduce CO2 into the barium sulfide solution in step S2 at a rate of 0.4 L / min until the pH of the mixed solution is 8, and then introduce CO2 at a rate of 1.7 L / min until the pH of the mixed solution is 6.5. Subsequently, add ozone with a volume fraction of 10% and a molar ratio of 1.4 times for desulfurization. Then wash with deionized water until the conductivity of the filtrate does not exceed 50 μS / cm, and then wash successively with 0.5% dilute ammonia water and ethanol with a concentration of 60%. Filter under vacuum, dry and crush to obtain barium carbonate. 2- According to the relevant detection standards of GB / T 1614 - 2021 for industrial barium carbonate, detect the product. The results are as follows: the purity of barium carbonate is not less than 99.91%, the chloride ion content does not exceed 8 ppm, the sulfide content is about 14 ppm, the sulfate content is about 0.02%, the sulfite is about 0.003%, and the iron ion is about 4 ppm.

[0044] Example 5

[0045] This example provides a production method of industrial-grade barium carbonate, including the following steps: ​S1. After pre-treating the crude barium sulfide, dissolve the barium sulfide powder and 0.1% thiourea by mass of the barium sulfide powder in 65°C hot water under the protection of nitrogen (purity ≥ 99.99%), filter while hot at a pressure of 0.08MPa to remove insoluble impurities (such as silicates, unreacted barium sulfate), and then concentrate under reduced pressure at a pressure of -0.1MPa, cool to 35°C at a rate of 4°C / min, keep the temperature constant for 15min, and then cool to 20°C at a rate of 0.8°C / min to obtain a barium sulfide concentrate with a concentration of 22%; S2, adjusting the pH value of the barium sulfide concentrate in step S1 to 10 with a 10% sodium hydroxide solution, adding 0.05% disodium EDTA solution and 0.08% thiourea solution to the barium sulfide concentrate in sequence under stirring, and filtering through a 0.24 μm PVDF membrane to obtain a barium sulfide solution; The barium sulfide solution prepared in step S2 is tested, and the purity of the barium sulfide solution is not less than 99.85%, the water-insoluble matter is not more than 0.5ppm, the chloride ion content is not more than 30ppm, the thiosulfate content is about 0.060%, and the Fe 3+ / Ca 2+ Metal ion content is <8ppm, NTU <8.7.

[0046] S3, under nitrogen atmosphere, CO2 was introduced into the barium sulfide solution of step S2 at a rate of 0.45 L / min until the pH of the mixed solution was 8.5, and then CO2 was introduced at a rate of 1.65 L / min until the pH of the mixed solution was 6.5, and then S 2- Desulfurization is carried out with ozone of 10% by volume at a molar ratio of 1.45, followed by washing with deionized water until the conductivity of the filtrate does not exceed 50 μS / cm, and then washing with 0.5% dilute ammonia water and 60% ethanol in sequence, vacuum filtering, drying and crushing to obtain barium carbonate.

[0047] The product was tested according to the relevant testing standards of GB / T 1614-2021 Industrial Barium Carbonate. The results are: the purity of barium carbonate is not less than 99.95%, the chloride ion content does not exceed 5ppm, the sulfide content is about 10ppm, the sulfate content is about 0.015%, the sulfite content is about 0.002%, and the iron ion content is about 2ppm.

[0048] Example 6 This embodiment provides a method for producing industrial-grade barium carbonate, comprising the following steps: S1. After pre-treating the crude barium sulfide, under the protection of nitrogen (purity ≥ 99.99%), dissolve barium sulfide powder and 0.1% (by mass of barium sulfide powder) of thiourea in hot water at 60 °C, and filter while it is hot under a pressure of 0.06 MPa to remove insoluble impurities (such as silicates and unreacted barium sulfate). Then, under a pressure of -0.08 MPa, concentrate under reduced pressure, cool at a rate of 3 °C / min to 35 °C, keep the temperature constant for 15 min, and then cool at a rate of 0.85 °C / min to 20 °C to obtain a barium sulfide concentrate with a concentration of 18%. S2. Adjust the barium sulfide concentrate obtained in step S1 to a pH value of 10 with 10% sodium hydroxide solution. Under stirring conditions, sequentially add 0.07% ascorbic acid solution and 0.1% thiourea solution to the barium sulfide concentrate, and filter through a 0.23 μm PVDF membrane to obtain a barium sulfide solution. Detect the barium sulfide solution prepared in step S2. The purity of the barium sulfide solution is not less than 99.84%, the water-insoluble matter does not exceed 0.8 ppm, the chloride ion content does not exceed 35 ppm, the thiosulfate content is about 0.065%, Fe 3+ / Ca 2+ The content of metal ions such as <9 ppm, and NTU < 8.3.

[0049] S3. Under a nitrogen atmosphere, introduce CO2 into the barium sulfide solution obtained in step S2 at a rate of 0.35 L / min until the pH of the mixed solution is 8, and then introduce CO2 at a rate of 1.6 L / min until the pH of the mixed solution is 7. Subsequently, add S 2- 1.35 times the molar ratio of ozone with a volume fraction of 12% for desulfurization. Then, wash with deionized water until the conductivity of the filtrate does not exceed 50 μS / cm, and then wash successively with 0.5% dilute ammonia water and ethanol with a concentration of 60%. Filter under vacuum and dry and crush to obtain barium carbonate.

[0050] According to the relevant detection standards of industrial barium carbonate in GB / T 1614 - 2021, detect the product. The results are as follows: the purity of barium carbonate is not less than 99.93%, the chloride ion content does not exceed 7 ppm, the sulfide content is about 12 ppm, the sulfate content is about 0.017%, the sulfite is about 0.0025%, and the iron ion is about 3 ppm.

[0051] Comparative Example 1 The difference from Example 5 is that in step S2, no antioxidant was added, and the other steps remained unchanged.

[0052] Detect the barium sulfide solution prepared in step S2. The purity of the barium sulfide solution is not less than 99.78%, the water-insoluble matter does not exceed 2 ppm, the chloride ion content does not exceed 45 ppm, the thiosulfate content is about 0.1%, Fe3+ / Ca 2+ The content of metal ions such as <12 ppm.

[0053] According to the relevant detection standards of industrial barium carbonate in GB / T 1614-2021, the product was detected. The results are as follows: the purity of barium carbonate is not less than 99.88%, the chloride ion content does not exceed 12 ppm, the sulfide content is about 15 ppm, the sulfate content is about 0.022%, the sulfite is about 0.0035%, and the iron ion is about 5 ppm.

[0054] Comparative Example 2 The difference from Example 5 is that in step S2, no hydrolysis inhibitor was added, and the other steps remained unchanged.

[0055] The prepared barium sulfide solution in step S2 was detected. The purity of the barium sulfide solution is not less than 99.75%, the water-insoluble matter does not exceed 3 ppm, the chloride ion content does not exceed 50 ppm, the thiosulfate content is about 0.12%, Fe 3+ / Ca 2+ The content of metal ions such as <15 ppm.

[0056] According to the relevant detection standards of industrial barium carbonate in GB / T 1614-2021, the product was detected. The results are as follows: the purity of barium carbonate is not less than 99.85%, the chloride ion content does not exceed 15 ppm, the sulfide content is about 18 ppm, the sulfate content is about 0.025%, the sulfite is about 0.004%, and the iron ion is about 6 ppm.

[0057] Comparative Example 3 The difference from Example 5 is that in step S2, no antioxidant and hydrolysis inhibitor were added, and the other steps remained unchanged.

[0058] The prepared barium sulfide solution in step S2 was detected. The purity of the barium sulfide solution is not less than 99.70%, the water-insoluble matter does not exceed 4 ppm, the chloride ion content does not exceed 60 ppm, the thiosulfate content is about 0.15%, Fe 3+ / Ca 2+ The content of metal ions such as <20 ppm.

[0059] According to the relevant detection standards of industrial barium carbonate in GB / T 1614-2021, the product was detected. The results are as follows: the purity of barium carbonate is not less than 99.80%, the chloride ion content does not exceed 20 ppm, the sulfide content is about 20 ppm, the sulfate content is about 0.03%, the sulfite is about 0.005%, and the iron ion is about 8 ppm.

[0060] It can be seen from the combination of Example 5 and Comparative Examples 1 to 3: Taking thiosulfate in the barium sulfide solution as an example, the thiosulfate content in the barium sulfide solution of Example 5 is about 0.060%. In Comparative Example 1, no antioxidant was added, and the thiosulfate content in its barium sulfide solution increased to about 0.1%, an increase of 0.04% compared to Example 5, that is, an increase of about 67%. In Comparative Example 2, no hydrolysis inhibitor was added, and the thiosulfate content in its barium sulfide solution increased to about 0.12%, a 100% increase compared to the value of Example 5. In Comparative Example 3, neither antioxidant nor hydrolysis inhibitor was added, and the thiosulfate content in the barium sulfide solution rose to about 0.15%, an increase of about 0.09% compared to Example 5, that is, an increase of 150%. In addition, in the finally obtained barium carbonate product, the chloride ion content in Example 5 is also much lower than that in Comparative Examples 1 to 3. This is because the antioxidant blocks the coprecipitation and catalytic oxidation of metal ions and chloride ions, and at the same time the hydrolysis inhibitor reduces the generation of thiosulfate and avoids the formation of stable complexes with chloride ions, thereby achieving the effect of jointly reducing the chloride ion content.

[0061] This shows that the antioxidant and hydrolysis inhibitor selected in the present invention can effectively inhibit the generation of by-products and are of great significance in improving product purity and reducing impurity content.

[0062] Based on the above examples, taking Example 5 as an example, the inventor further analyzed the influence of the dosages of the antioxidant and hydrolysis inhibitor on the barium sulfide solution as follows, and the results are shown in Table 1.

[0063] Table 1 Analysis of Additive Dosages and Effects

[0064] It can be seen from Table 1 that in Comparative Example 4, due to the reduction in the dosages of the antioxidant and hydrolysis inhibitor, the oxidation reaction in the system was intensified and the hydrolysis reaction could not be effectively controlled, which led to a significant increase in the by-product thiosulfate. At the same time, the chloride ion content also increased significantly due to the decrease in the impurity removal efficiency. In Comparative Example 5, excessive amounts of antioxidant and hydrolysis inhibitor were used, but the contents of thiosulfate and chloride ions were similar to those in Example 5, indicating that excessive use of additives does not bring better effects, but instead leads to an increase in production costs, and even continued increase in dosage will cause unnecessary side reactions. Considering Comparative Examples 6 to 9 comprehensively, the antioxidant can improve the overall impurity control effect, while the dosage of the hydrolysis inhibitor is directly related to the amount of by-products generated. Single increase or decrease in the dosage of the antioxidant or hydrolysis inhibitor may lead to an increase in impurities and thus affect product quality.

[0065] Comparative Example 10 The difference from Example 5 is that in step S2, it is not filtered through the PVDF membrane, and the remaining steps remain unchanged.

[0066] The barium sulfide solution prepared in step S2 is detected. The purity of the barium sulfide solution is not less than 99.80%, the water-insoluble matter does not exceed 5 ppm, the chloride ion content does not exceed 55 ppm, the thiosulfate content is about 0.11%, and the content of metal ions such as Fe 3+ / Ca 2+ is less than 18 ppm.

[0067] According to the relevant detection standards of industrial barium carbonate in GB / T 1614-2021, the product is detected. The results are as follows: the purity of barium carbonate is not less than 99.85%, the chloride ion content does not exceed 18 ppm, the sulfide content is about 16 ppm, the sulfate content is about 0.023%, the sulfite is about 0.0038%, and the iron ion is about 7 ppm.

[0068] Comparative Example 11 The difference from Example 5 is that in step S3, CO2 is introduced at a rate of 1.0 L / min until the pH of the mixed solution is 6.5, and the other steps remain unchanged.

[0069] According to the relevant detection standards of industrial barium carbonate in GB / T 1614-2021, the product is detected. The results are as follows: the purity of barium carbonate is not less than 99.90%, the chloride ion content does not exceed 10 ppm, the sulfide content is about 14 ppm, the sulfate content is about 0.019%, the sulfite is about 0.0032%, and the iron ion is about 4 ppm.

[0070] Comparative Example 12 The difference from Example 5 is that in step S3, desulfurization treatment is not carried out.

[0071] According to the relevant detection standards of industrial barium carbonate in GB / T 1614-2021, the product is detected. The results are as follows: the purity of barium carbonate does not exceed 99.80%, the chloride ion content does not exceed 10 ppm, the sulfide content is not less than 50 ppm, the sulfate content is not less than 0.05%, the sulfite is not less than 0.01%, and the iron ion is not less than 6 ppm.

[0072] Combined with Example 5 and Comparative Example 12: Through ozone desulfurization (S 2- :O3 = 1:1.45), the residual sulfides (such as S 2- , S2O3 2- ) are effectively oxidized and converted into soluble SO4 2- and then removed by water washing, thereby significantly reducing the contents of sulfide, sulfate and sulfite in the final product. At the same time, the antioxidant disodium EDTA has better chelating ability for Fe 3+ , but if Fe 2+ not completely oxidized to Fe 3+ or wrapped by sulfide to form FeS colloid, then disodium EDTA may not be completely removed. However, the strong oxidizing property of ozone in step S3 can synergistically remove Fe 2+ , converting it to Fe 3+ , and forming a colloidal precipitate under the weak alkaline condition of pH 6.5 - 8.5, which is further separated and removed during the subsequent washing process, reducing the iron ion residue to 2 ppm. In addition, ozone desulfurization oxidizes sulfide to sulfate with higher water solubility, reducing the adsorption and wrapping effect of sulfide on chloride ions (Cl - ), making it easier to remove Cl in the subsequent water washing - , ultimately achieving an improvement in the purity of barium carbonate.

[0073] In summary, adopting the method for preparing industrial barium carbonate of the present invention, using barium sulfide with low impurities and high purity as the raw material, ensures the high quality and high purity of the final barium carbonate product.

[0074] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A production method of industrial barium carbonate, characterized in that, It includes the following steps: S1. After pre-treating the crude barium sulfide, under the protection of inert gas, perform hot filtration, then perform vacuum concentration, and cool to obtain a concentrated barium sulfide solution; S2. Adjust the pH of the concentrated barium sulfide solution in step S1 to be alkaline. Under stirring conditions, add an antioxidant and a hydrolysis inhibitor thereto, and after filtration through a PVDF membrane, obtain a barium sulfide solution; S3. Under the protection of inert gas, introduce carbon dioxide into the barium sulfide solution in step S2, then perform desulfurization washing, vacuum filtration, drying and pulverization to obtain barium carbonate.

2. The production method of industrial barium carbonate according to claim 1, characterized in that, In step S1, the temperature of the hot filtration is 60-70 °C, and the pressure is 0.05-1 MPa.

3. The production method of industrial barium carbonate according to claim 2, characterized in that, In step S1, the pressure of the vacuum concentration is -0.08 to -0.1 MPa, and the concentration of the concentrated barium sulfide solution is 20-22%.

4. The production method of industrial barium carbonate according to claim 1, characterized in that, In step S2, adjust the pH value of the concentrated barium sulfide solution in step S1 to 9.5-10.

5. The production method of industrial barium carbonate according to claim 4, characterized in that, In step S2, the antioxidant is selected from ascorbic acid and / or disodium EDTA, and the hydrolysis inhibitor is selected from thiourea and / or sodium citrate; The mass ratio of the concentrated barium sulfide solution, the antioxidant and the hydrolysis inhibitor is 1000:(0.5-1.0):(0.6-1.2).

6. The production method of industrial barium carbonate according to claim 4, characterized in that, In step S2, the pore size of the PVDF membrane is 0.22-0.26 μm.

7. The production method of industrial barium carbonate according to claim 1, characterized in that, In step S3, the way of introducing carbon dioxide is: introduce it at a rate of 0.3-0.5 L / min until the pH of the mixed solution is 8-8.5; then introduce it at a rate of 1.5-1.8 L / min until the pH of the mixed solution is 6.5-7.

8. The production method of industrial barium carbonate according to claim 7, characterized in that, In step S3, the desulfurizer is ozone with a volume fraction of 8-12%; the molar ratio of the ozone to S 2- is 1.2-1.5:

1.

9. An industrial-grade barium carbonate, characterized in that, Prepared by the production method according to any one of claims 1-8.

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