A method for producing barium hydroxide monohydrate

Abstract

This invention relates to the technical field of barium hydroxide preparation, specifically to a method for producing barium hydroxide monohydrate. The method includes: pulverizing barite raw material; mixing the pulverized barite with rice husk ash and soda ash; calcining at 1100-1200℃ and holding at that temperature for 90-120 minutes; then cooling the mixture in a kiln to below 80℃ to obtain porous crude barium oxide; dispersing the crude barium oxide in water; filtering and washing the residue with deionized water to obtain the filtrate; heating the filtrate to 80-85℃; slowly adding a mixed desulfurizing agent composed of zinc oxide, calcium oxide, and manganese tetroxide for desulfurization; filtering and washing to obtain a barium hydroxide solution; concentrating and crystallizing to obtain Ba(OH)₂·8H₂O crystals; and then drying and dehydrating under vacuum to obtain barium hydroxide monohydrate. The purpose of this invention is to provide a method for producing barium hydroxide monohydrate that achieves low-cost, simple, stable product quality, and environmentally friendly production.

Description

Technical Field

[0001] This invention relates to the technical field of barium hydroxide preparation, and specifically to a method for producing barium hydroxide monohydrate. Background Technology

[0002] Barium hydroxide monohydrate, as an important inorganic chemical raw material, plays an indispensable role in many industrial fields such as electronics, ceramics, glass, plastics, and rubber. With the continuous development of these industries, higher demands are being placed on the quality and yield of barium hydroxide monohydrate. Therefore, developing efficient, environmentally friendly, and low-cost production methods for barium hydroxide monohydrate is of significant practical importance.

[0003] Existing production methods involve lengthy processes, including multiple reaction steps and separation / purification procedures. This complexity not only increases operational difficulty but also increases the risk of malfunctions and inconsistent product quality. Furthermore, existing methods suffer from impurity introduction and incomplete reactions, resulting in inconsistent quality of the produced barium hydroxide monohydrate. In the barite-based process, the barite may contain other metallic impurities such as calcium, magnesium, and iron, which can enter the product during the reaction, affecting its purity and performance. These existing barium hydroxide monohydrate production methods present numerous problems regarding raw material costs, process complexity, product quality, and environmental pollution, severely hindering the sustainable development of the barium hydroxide monohydrate industry. Therefore, developing a low-cost, simple, stable, and environmentally friendly barium hydroxide monohydrate production method is of paramount urgency and necessity. Based on this, this invention proposes a method for producing barium hydroxide monohydrate. Summary of the Invention

[0004] The purpose of this invention is to provide a method for producing barium hydroxide monohydrate that achieves low-cost, simple, stable product quality, and environmentally friendly production.

[0005] This invention provides a method for producing barium hydroxide monohydrate, comprising the following steps:

[0006] (1) The raw material of barite is crushed, and the crushed barite is mixed evenly with rice husk ash and soda ash. It is calcined at 1100-1200℃ and kept at the temperature for 90-120 minutes. Then it is cooled to below 80℃ in the kiln and taken out of the furnace to obtain porous crude barium oxide.

[0007] (2) Crude barium oxide is dispersed in water, filtered, and the residue is washed with deionized water and combined to obtain filtrate. The filtrate is heated to 80-85℃, and a mixed desulfurizing agent consisting of zinc oxide, calcium oxide and manganese tetroxide is slowly added for desulfurization. After filtration and washing, barium hydroxide solution is obtained. After concentration and crystallization, Ba(OH)2·8H2O crystals are obtained. Then, the crystals are dried and dehydrated under vacuum to obtain barium hydroxide monohydrate.

[0008] Furthermore, the ratio of the pulverized barite, rice husk ash, and soda ash is 100:15-20:10-12.

[0009] Furthermore, the weight ratio of the mixed desulfurizing agent to crude barium oxide is 3-5%.

[0010] Furthermore, the weight ratio of zinc oxide, calcium oxide and manganese tetroxide in the mixed desulfurizing agent is 1:1:0.3-0.5.

[0011] Furthermore, the number of times the residue is cleaned is 2-3 times.

[0012] Furthermore, the stirring speed during desulfurization is 200-250 rpm, and the stirring time is 30-40 min.

[0013] Further, the concentration is carried out at 65-75°C and under a vacuum of -0.08±0.001MPa to a Ba(OH)2 concentration of 30-35wt%.

[0014] Furthermore, the crystallization is carried out by cooling to 25-30℃ and allowing it to stand for 6-8 hours to crystallize, thereby obtaining Ba(OH)2·8H2O crystals.

[0015] Furthermore, the drying and dehydration involves drying the crystals in a vacuum oven at 60-70℃ and -0.095±0.005MPa for 4-5 hours.

[0016] The beneficial effects of this invention are as follows:

[0017] This technical solution constructs a highly efficient decomposition system through the synergistic effect of barite, rice husk ash, and soda ash. Barite, as a barium source, provides skeletal support for subsequent reactions due to its natural mineral structure; rice husk ash, as an aluminosilicate regulator, forms microscopic gas chambers during calcination due to its porous structure, promoting heat and mass transfer efficiency; and soda ash, as an alkaline additive, significantly improves barium oxide conversion by lowering the activation energy of barite decomposition. The synergistic effect of these three components overcomes the limitations of the traditional single alkali fusion method, achieving low-temperature, high-efficiency decomposition: the introduction of rice husk ash not only lowers the calcination temperature window, but its mineral components also inhibit barium oxide particle agglomeration, forming a porous structure with a high specific surface area, creating favorable conditions for the subsequent water leaching process.

[0018] This invention employs a ZnO-CaO-Mn3O4 composite desulfurizing agent to construct a three-stage gradient desulfurization system. The first stage, ZnO, preferentially captures free sulfur in the solution through chemical adsorption. 2-The first stage generates thermodynamically stable ZnS precipitate; the second stage, CaO, increases the pH of the system (pH>12), promoting the conversion of sparingly soluble BaSO3 into more easily filterable CaSO3; the third stage, Mn3O4, acts as an oxidation catalyst, oxidizing residual low-valent sulfur (S2O3²⁻, etc.) to SO4. 2- Ultimately, MnS2 precipitate is formed. This gradient mechanism achieves the removal of sulfur impurities across the entire spectrum: ZnO ensures the main desulfurization efficiency, CaO regulates the reaction environment, and Mn3O4 completes deep purification, with the three achieving synergistic effects.

[0019] This invention achieves a precise phase transition from octadecahydrate to monohydrate using vacuum gradient dehydration technology. In the initial concentration stage, the evaporation rate is controlled to bring the solution to a supersaturation critical point, inducing uniform formation of octadecahydrate crystal nuclei. Subsequently, in the cooling crystallization stage, a temperature gradient is used to reduce the solute solubility, promoting slow crystal growth and the formation of a regular, plate-like structure. Finally, in the vacuum drying stage, precise control of the water vapor partial pressure causes the crystal water molecules to be removed in a specific sequence: first, surface-adsorbed water evaporates; then, interlayer water molecules are gradually released through hydrogen bond recombination; and finally, lattice water is directionally removed under vacuum, avoiding crystal collapse caused by disordered dehydration. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1

[0022] This embodiment provides a method for producing barium hydroxide monohydrate, the steps of which include:

[0023] After crushing the barite and passing it through a 100-mesh sieve, and passing the rice husk ash through a 100-mesh sieve, the barite powder, rice husk ash, and soda ash were mixed in a mixer in a weight ratio of 100:18:11 until uniform. The mixture was placed in a rotary kiln, calcined at 1150℃ and held at that temperature for 105 minutes, and then cooled to 80℃ with the kiln before being removed from the furnace to obtain porous crude barium oxide.

[0024] The total leaching rate of barium when obtaining porous crude barium oxide was 66.7%;

[0025] Crude barium oxide was dispersed in deionized water at 75℃ at a dosage ratio of 150 g / L, stirred at 300 rpm for 1 h, filtered while hot, with a filter cloth precision of 5 μm, and the residue was washed twice with deionized water at 60℃. The wash water was combined with the filtrate. The combined filtrate was heated to 82℃, and a mixed desulfurizing agent consisting of zinc oxide, calcium oxide and manganese tetroxide in a weight ratio of 1:1:0.4 was slowly added. The weight ratio of the mixed desulfurizing agent to crude barium oxide was 4%, and the mixture was stirred at 220 rpm for 35 min. The mixture was then filtered using a plate and frame filter press with a filter membrane pore size of 1 μm.

[0026] The filtrate was concentrated at 70℃ and -0.08MPa vacuum to a Ba(OH)2 concentration of 32wt%, cooled to 28℃, and allowed to crystallize for 7h. After centrifugation at 1100rpm for 12min, Ba(OH)2·8H2O crystals were obtained. The mother liquor was returned to the concentration step, and the crystals were dried in a vacuum oven at 65℃ and -0.095MPa for 2.5h to remove 7 molecules of water of crystallization, thus obtaining Ba(OH)2·H2O.

[0027] The total leaching rate of barium when obtaining Ba(OH)2·H2O was 78.5%; the purity of the final product was 99.4%.

[0028] Example 2

[0029] This embodiment provides a method for producing barium hydroxide monohydrate, the steps of which include:

[0030] After crushing the barite and passing it through a 100-mesh sieve, and passing the rice husk ash through a 100-mesh sieve, the barite powder, rice husk ash, and soda ash were mixed in a mixer in a weight ratio of 100:15:10 until uniform. The mixture was placed in a rotary kiln, calcined at 1100℃ and held at that temperature for 90 minutes, and then cooled to 80℃ with the kiln before being removed from the furnace to obtain porous crude barium oxide.

[0031] The total leaching rate of barium when obtaining porous crude barium oxide was 66.5%;

[0032] Crude barium oxide was dispersed in deionized water at 70℃ at a dosage ratio of 150 g / L, stirred at 300 rpm for 1 h, filtered while hot, with a filter cloth precision of 5 μm, and the residue was washed twice with deionized water at 60℃. The wash water was combined with the filtrate. The combined filtrate was heated to 80℃, and a mixed desulfurizing agent consisting of zinc oxide, calcium oxide and manganese tetroxide in a weight ratio of 1:1:0.3 was slowly added. The weight ratio of the mixed desulfurizing agent to crude barium oxide was 3%, and the mixture was stirred at 200 rpm for 30 min. The mixture was then filtered using a plate and frame filter press with a filter membrane pore size of 1 μm.

[0033] The filtrate was concentrated at 65℃ and -0.08MPa vacuum to a Ba(OH)2 concentration of 30wt%, cooled to 25℃, and allowed to stand for crystallization for 6h. After centrifugation at 1000rpm for 10min, Ba(OH)2·8H2O crystals were obtained. The mother liquor was returned to the concentration step, and the crystals were dried in a vacuum oven at 60℃ and -0.095MPa for 2h to remove 7 molecules of water of crystallization, thus obtaining Ba(OH)2·H2O.

[0034] The total leaching rate of barium when obtaining Ba(OH)2·H2O was 78.2%; the purity of the final product was 99.2%.

[0035] Example 3

[0036] This embodiment provides a method for producing barium hydroxide monohydrate, the steps of which include:

[0037] After crushing the barite and passing it through a 100-mesh sieve, and passing the rice husk ash through a 100-mesh sieve, the barite powder, rice husk ash, and soda ash were mixed in a mixer in a weight ratio of 100:20:12 until uniform. The mixture was placed in a rotary kiln, calcined at 1200℃ and held at that temperature for 120 minutes, and then cooled to 80℃ with the kiln before being removed from the furnace to obtain porous crude barium oxide.

[0038] The total leaching rate of barium when obtaining porous crude barium oxide was 66.2%.

[0039] Crude barium oxide was dispersed in deionized water at 80℃ at a dosage ratio of 150 g / L, stirred at 300 rpm for 1 h, filtered while hot, with a filter cloth precision of 5 μm, and the residue was washed twice with deionized water at 60℃. The wash water was combined with the filtrate. The combined filtrate was heated to 85℃, and a mixed desulfurizing agent consisting of zinc oxide, calcium oxide and manganese tetroxide in a weight ratio of 1:1:0.5 was slowly added. The weight ratio of the mixed desulfurizing agent to crude barium oxide was 4%, and the mixture was stirred at 250 rpm for 40 min. The mixture was then filtered using a plate and frame filter press with a filter membrane pore size of 1 μm.

[0040] The filtrate was concentrated at 75℃ and -0.08MPa vacuum to a Ba(OH)2 concentration of 35wt%, cooled to 30℃, and allowed to crystallize for 8 hours. After centrifugation at 1200rpm for 15 minutes, Ba(OH)2·8H2O crystals were obtained. The mother liquor was returned to the concentration step, and the crystals were dried in a vacuum oven at 70℃ and -0.095MPa for 3 hours to remove 7 molecules of water of crystallization, thus obtaining Ba(OH)2·H2O.

[0041] The total leaching rate of barium when Ba(OH)2·H2O was 77.9%; the purity of the final product was 99.3%.

[0042] Comparative Example 1

[0043] Based on Example 1, adjustments were made. Unlike Example 1, the calcination temperature in this comparative example was adjusted to 1300℃.

[0044] The total leaching rate of barium was 58.3% when obtaining porous crude barium oxide; the total leaching rate of barium was 68.9% when obtaining Ba(OH)2·H2O; and the purity of the final product was 98.1%.

[0045] Comparative Example 2

[0046] Based on Example 1, adjustments were made. Unlike Example 1, the calcination holding time in this comparative example was adjusted to 3.5 hours.

[0047] The total leaching rate of barium was 64.8% when obtaining porous crude barium oxide; the total leaching rate of barium was 76.5% when obtaining Ba(OH)2·H2O; and the purity of the final product was 98.7%.

[0048] Comparative Example 3

[0049] Based on Example 1, adjustments were made. Unlike Example 1, in this comparative example, a mixed desulfurizing agent consisting of zinc oxide, calcium oxide, and manganese tetroxide was slowly added to the filtrate at room temperature for desulfurization.

[0050] The total leaching rate of barium was 66.7% when obtaining porous crude barium oxide; the total leaching rate of barium was 72.1% when obtaining Ba(OH)2·H2O; and the purity of the final product was 97.5%.

[0051] Comparative Example 4

[0052] This comparative example is an adjustment based on Example 1. Unlike Example 1, no soda ash was added as a raw material in this comparative example.

[0053] The total leaching rate of barium was 41.2% when obtaining porous crude barium oxide; the total leaching rate of barium was 49.8% when obtaining Ba(OH)2·H2O; and the purity of the final product was 92.3%.

[0054] Comparative Example 5

[0055] This comparative example is an adjustment based on Example 1. Unlike Example 1, zinc oxide was not added as a raw material in this comparative example.

[0056] The total leaching rate of barium was 66.7% when obtaining porous crude barium oxide; the total leaching rate of barium was 75.3% when obtaining Ba(OH)2·H2O; and the purity of the final product was 98.0%.

[0057] Comparative Example 6

[0058] This comparative example is an adjustment based on Example 1. Unlike Example 1, calcium oxide was not added as a raw material in this comparative example.

[0059] The total leaching rate of barium was 66.7% when obtaining porous crude barium oxide; the total leaching rate of barium was 76.8% when obtaining Ba(OH)2·H2O; and the purity of the final product was 98.9%.

[0060] Comparative Example 7

[0061] This comparative example is an adjustment based on Example 1. Unlike Example 1, manganese tetroxide was not added as a raw material in this comparative example.

[0062] The total leaching rate of barium was 66.7% when obtaining porous crude barium oxide; the total leaching rate of barium was 77.1% when obtaining Ba(OH)2·H2O; and the purity of the final product was 98.8%.

[0063] Comparative Example 8

[0064] Based on Example 1, adjustments were made. Unlike Example 1, the conditions for removing 7 molecules of water of crystallization in this comparative example were adjusted to drying in a vacuum oven at 65°C and -0.08MPa for 2.5 hours.

[0065] The total leaching rate of barium was 66.7% when obtaining porous crude barium oxide; the total leaching rate of barium was 78.5% when obtaining Ba(OH)2·H2O; and the purity of the final product was 99.0%.

[0066] Comparative Example 9

[0067] Based on Example 1, adjustments were made. Unlike Example 1, in this comparative example, the filtrate was concentrated at 70°C and under a vacuum of -0.095 MPa to a Ba(OH)2 concentration of 32 wt%.

[0068] The total leaching rate of barium was 66.7% when obtaining porous crude barium oxide; the total leaching rate of barium was 78.5% when obtaining Ba(OH)2·H2O; and the purity of the final product was 99.1%.

[0069] The barium leaching rate and product purity of the aforementioned examples and comparative examples are shown in Table 1 below.

[0070] Table 1: Barium Leaching Rate and Product Purity

[0071]

[0072] Based on the foregoing, in Comparative Example 1, the excessively high calcination temperature led to a significant decrease in barium leaching rate and product purity. 1300℃ may cause barium oxide sintering or exacerbate side reactions, such as the formation of barium silicate, reducing reactivity and increasing energy consumption. In Comparative Example 2, extending the holding time did not improve the leaching rate; instead, it slightly reduced purity and efficiency. Excessive calcination may cause material agglomeration or impurities to melt and encapsulate barium oxide, hindering the subsequent water leaching process. In Comparative Example 3, the low-temperature desulfurization efficiency was significantly reduced. A high-temperature environment of 80-85℃ is necessary for the desulfurizing agent (ZnO / CaO / Mn3O4) to fully react with sulfides; at room temperature, impurities are not thoroughly removed, leading to a decrease in the purity of the final product. In Comparative Example 4, soda ash is a key aid in the decomposition of barite. Without soda ash, barite cannot be fully converted into barium oxide, resulting in a collapse in leaching rate and purity. In Comparative Example 5, the lack of zinc oxide significantly reduced the desulfurization effect. ZnO has the strongest adsorption capacity for sulfides such as BaS, forming ZnS. Its deficiency leads to increased residual sulfur impurities, affecting the final purity and leaching rate. In Comparative Example 6, the deficiency of calcium oxide had a relatively small impact on the results. CaO mainly assists in desulfurization to form CaS and adjusts pH, but ZnO and Mn3O4 can partially compensate for this function, so the decrease in purity and leaching rate is limited. In Comparative Example 7, the deficiency of manganese tetroxide slightly affected the desulfurization effect. Manganese tetroxide can deeply remove trace amounts of sulfur and heavy metal impurities. Its deficiency slightly reduced the product purity, but had little impact on the barium leaching rate. In Comparative Example 8, insufficient vacuum led to incomplete drying. At -0.08 MPa (originally -0.095 MPa), seven molecules of water could not be completely removed, and the residual water of crystallization reduced the product purity, but the barium leaching rate was not affected. In Comparative Example 9, over-concentration caused local crystallization. A higher vacuum (-0.095 MPa) accelerated concentration, but may cause Ba(OH)2 to precipitate prematurely, forming encapsulated impurities and slightly reducing the product purity.

[0073] Finally, it should be noted that the applicant declares that while the above embodiments illustrate the product and detailed preparation method of the present invention, the present invention is not limited to the above-described product and detailed preparation method, that is, it does not mean that the present invention must rely on the above-described product and detailed preparation method to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of excipients, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0074] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention. These simple modifications all fall within the protection scope of the present invention.

[0075] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0076] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for producing barium hydroxide monohydrate, characterized in that the steps include: include: (1) The raw material of barite is crushed, and the crushed barite is mixed evenly with rice husk ash and soda ash. It is calcined at 1100-1200℃ and kept at the temperature for 90-120 minutes. Then it is cooled to below 80℃ in the kiln and taken out of the furnace to obtain porous crude barium oxide. (2) Crude barium oxide is dispersed in water, filtered and the residue is washed with deionized water. The wash water is combined with the filtrate. The filtrate is heated to 80-85℃ and a mixed desulfurizing agent composed of zinc oxide, calcium oxide and manganese tetroxide is slowly added for desulfurization. After filtration and washing, barium hydroxide solution is obtained. After concentration and crystallization, Ba(OH)2·8H2O crystals are obtained. Then, the crystals are dried and dehydrated under a vacuum of -0.095MPa to obtain barium hydroxide monohydrate. The weight ratio of the crushed barite, rice husk ash, and soda ash is 100:(15-20):(10-12); the concentration is carried out at 65-75℃ and under vacuum of -0.08±0.001MPa to a Ba(OH)2 concentration of 30-35wt%; the crystallization is carried out by cooling to 25-30℃ and allowing it to stand for 6-8 hours to obtain Ba(OH)2·8H2O crystals.

2. The method for producing barium hydroxide monohydrate according to claim 1, characterized in that, The mixed desulfurizing agent is 3-5% of the weight of crude barium oxide.

3. The method for producing barium hydroxide monohydrate according to claim 1, characterized in that, The weight ratio of zinc oxide, calcium oxide and manganese tetroxide in the mixed desulfurizing agent is 1:1:(0.3-0.5).

4. The method for producing barium hydroxide monohydrate according to claim 1, characterized in that, The number of times the residue is cleaned is 2-3 times.

5. The method for producing barium hydroxide monohydrate according to claim 1, characterized in that, The stirring speed during desulfurization is 200-250 rpm, and the stirring time is 30-40 min.

6. The method for producing barium hydroxide monohydrate according to claim 1, characterized in that, The drying and dehydration process involves drying the crystals in a vacuum oven at 60-70°C for 2-3 hours.

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