Method for removing carbonate in sodium aluminate solution
By adding barium hydroxide to the sodium aluminate solution to generate barium carbonate precipitation and separation, the problem of carbonate accumulation is solved, the high purity of the sodium aluminate solution and the stability of aluminum hydroxide production are achieved, the cost is reduced and the resource utilization rate is improved.
Patent Information
- Application Number
- CN202510807344.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-17
- Publication Date
- 2025-09-16
AI Technical Summary
In the existing technology, the accumulation of carbonate ions in the sodium aluminate solution will lead to a decrease in the decomposition rate of sodium aluminate and an increase in the sodium oxide content of the product, affecting the production quality and evaporation efficiency of aluminum hydroxide. Traditional removal methods will introduce impurities that affect product purity and recovery rate.
Barium hydroxide solution is reacted with sodium aluminate solution to generate barium carbonate precipitate, and carbonate ions are removed by solid-liquid separation. The mass ratio of barium hydroxide to carbonate ions and the reaction conditions are controlled to ensure that the reaction is complete and no impurities are introduced.
It effectively removes carbonate ions, improves the purity and quality of sodium aluminate solution, ensures the stability of aluminum hydroxide production and produces high-purity products, reduces carbonate removal costs and achieves efficient recycling of resources.
Smart Images
Figure CN120646888A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of sodium aluminate solution purification, and in particular to a method for removing carbonate ions from a sodium aluminate solution. Background Art
[0002] When aluminum hydroxide is used as a raw material to prepare sodium aluminate solution by redissolving it with alkali or seed-based recycled mother liquor, carbon dioxide in the air reacts with caustic soda to form sodium carbonate. As the solution is recycled, carbonate ions accumulate and their concentration continues to rise. During the decomposition process, this reduces the decomposition rate of sodium aluminate, increases the sodium oxide content of the product, and refines the aluminum hydroxide. Furthermore, during the evaporation of the recycled mother liquor, crystals precipitate and form scaling, affecting evaporation efficiency. Therefore, this poses a significant threat to the production of redissolved aluminum hydroxide and must be strictly controlled.
[0003] At present, the commonly known method for removing carbonate ions is generally lime milk causticization, that is, adding lime milk (Ca(OH)2) to the sodium aluminate solution to make carbonate ions react with calcium ions to form CaCO3 precipitation for removal. The advantages of this method are simple operation and low cost, but due to the introduction of Ca 2+ The residual calcium content in aluminum hydroxide increases, affecting the product quality. At the same time, aluminate ions react with calcium ions to form calcium aluminate, which reduces the aluminum recovery rate and produces a large amount of calcium aluminate slag. Summary of the Invention
[0004] The present application provides a method for removing carbonate ions from a sodium aluminate solution to solve the following technical problem: how to reduce the carbonate ion content in the sodium aluminate solution.
[0005] In a first aspect, the present invention provides a method for removing carbonate from a sodium aluminate solution, comprising the following steps:
[0006] Obtaining a barium hydroxide solution with a set mass concentration;
[0007] adding the barium hydroxide solution to the sodium aluminate solution so that the barium hydroxide reacts with the carbonate in the sodium aluminate solution to produce a precipitation reaction, thereby obtaining a mixed solution including a precipitate;
[0008] performing solid-liquid separation on the mixed solution to obtain a refined sodium aluminate solution and a barium carbonate precipitate;
[0009] The set mass concentration is 20% to 50%;
[0010] The mass ratio of the barium hydroxide to the carbonate in the sodium aluminate is 2.5:1 to 3.5:1.
[0011] Optionally, obtaining the barium hydroxide solution having a set mass concentration specifically includes:
[0012] Barium hydroxide is mixed with a solvent having a set temperature to obtain a barium hydroxide solution having a set mass concentration.
[0013] Optionally, the set mass concentration is 30% to 50%.
[0014] Optionally, the set temperature is 80°C to 100°C.
[0015] Optionally, the mass ratio of the barium hydroxide to the carbonate in the sodium aluminate is 2.86:1 to 3.2:1.
[0016] Optionally, the reaction temperature of the precipitation reaction is 70° C. to 95° C.; and the reaction time is 0.5 h to 2 h.
[0017] Optionally, the sodium aluminate solution satisfies at least one of the following conditions: the alkali concentration in the sodium aluminate solution is 20 g / L to 230 g / L, and the alumina concentration is 10 g / L to 240 g / L.
[0018] Optionally, after the mixed solution is subjected to solid-liquid separation to obtain a refined sodium aluminate solution and a barium carbonate precipitate, the following steps may be further performed:
[0019] calcining and decarbonizing the barium carbonate precipitate to obtain barium oxide solid;
[0020] The barium oxide solid is mixed with a solvent to obtain a barium hydroxide solution with a set concentration.
[0021] Optionally, the temperature of the roasting and decarburization is 1400°C to 1500°C.
[0022] Optionally, the solvent is water.
[0023] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:
[0024] The embodiment of the present application provides a method for removing carbonate from a sodium aluminate solution, in which barium hydroxide is a key reagent for removing carbonate, and barium carbonate precipitate is generated by reacting with carbonate to achieve the removal of carbonate. The mass concentration (20% to 50%) is set to ensure that the barium hydroxide solution has sufficient reactivity and concentration, and can effectively react with the carbonate in the sodium aluminate solution to convert the dissolved carbonate into an insoluble barium carbonate precipitate, thereby achieving the removal of carbonate. The mass ratio of barium hydroxide to carbonate (2.5:1 to 3.5:1) and the reaction temperature are controlled to ensure the efficiency of the reaction and avoid the introduction of impurities or incomplete reaction due to excessive or insufficient barium hydroxide. Finally, the barium carbonate precipitate is separated from the solution by solid-liquid separation (such as centrifugation or filtration separation), thereby obtaining a refined sodium aluminate solution after the removal of carbonate. This step ensures that the carbonate is effectively removed while retaining the useful components of the sodium aluminate solution, thereby improving the purity and quality of the solution. This method can not only efficiently remove carbonate, but also ensure the quality of the sodium aluminate solution and the compatibility with subsequent processes. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.
[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.
[0027] Figure 1 Schematic diagram of a process for removing carbonate from a sodium aluminate solution according to some embodiments of the present application;
[0028] Figure 2 The figure is a flow chart of a method for removing carbonate from a sodium aluminate solution according to some embodiments of the present application. DETAILED DESCRIPTION
[0029] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.
[0030] The range descriptions described in this article, such as numerical ranges, ratio ranges, etc., include all possible sub-ranges and single numerical values within the range. For example, the range description of "1 to 6" or "1~6" covers all sub-ranges from 1 to 6 (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6). Unless otherwise specified, the terms "including", "comprising", etc. used in this article mean "including but not limited to"; relational terms such as "first" and "second" are only used to distinguish different entities or operations, and do not imply an actual sequence or association relationship; "and / or" means that multiple situations can exist alone or at the same time; expressions such as "at least one", "multiple", and "at least one" refer to any combination of corresponding objects, including a combination of single or multiple objects. The proportional relationships involved in the article, such as mass ratios, molar ratios, etc., should be understood as the corresponding relationship between the first and second terms of the proportional formula in the order of description. The raw materials, reagents, instruments and equipment used in this article can be purchased on the market or prepared by existing methods.
[0031] Figure 1 Schematic diagram of a process for removing carbonate from a sodium aluminate solution according to some embodiments of the present application;
[0032] like Figure 1 As shown, the embodiment of the present application provides a method for removing carbonate ions in a sodium aluminate solution, comprising:
[0033] S1. Obtaining a barium hydroxide solution having a set mass concentration, wherein the set mass concentration is 20% to 50%;
[0034] In step S1, a barium hydroxide solution having a set mass concentration is obtained and used as a carbonate removal agent to provide a reaction raw material for a subsequent precipitation reaction. The mass concentration of the barium hydroxide solution can be 20%, 25%, 30%, 35%, 40%, 45% or 50%.
[0035] S2. adding the barium hydroxide solution to the sodium aluminate solution to cause a precipitation reaction between the barium hydroxide and the carbonate in the sodium aluminate solution to obtain a mixed solution including a precipitate; wherein the mass ratio of the barium hydroxide to the carbonate in the sodium aluminate is 2.5:1 to 3.5:1;
[0036] In step S2, after the barium hydroxide solution is mixed with the sodium aluminate solution, the barium ions therein react with the carbonate ions in the sodium aluminate solution to form a barium carbonate precipitate, thereby removing the carbonate ions in the sodium aluminate solution. The principle of this method is simple and easy to implement, and the hydroxide ions dissolve in the sodium aluminate solution and can further form sodium hydroxide with the sodium ions, becoming a beneficial substance in the production of aluminum hydroxide. The mass ratio of the barium hydroxide to the carbonate ions in the sodium aluminate can be 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3.0:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1 or 3.5:1.
[0037] S3. Performing solid-liquid separation on the mixed solution to obtain a refined sodium aluminate solution and a barium carbonate precipitate.
[0038] In step S3, the sodium aluminate refined solution and the barium carbonate precipitate in the mixed solution are completely separated by solid-liquid separation, thereby effectively reducing the carbonate concentration in the sodium aluminate solution to obtain a sodium aluminate solution with a low carbonate concentration.
[0039] In the above embodiment, the method utilizes the carbonation principle to produce a sodium aluminate solution with a low carbonate concentration, effectively eliminating the impact of carbonate on the production of aluminum hydroxide by the redissolution process, thereby ensuring the stability of the aluminum hydroxide production process and the high purity of the product. Experimental results show that this method can produce a product with a purity greater than 99.5% when preparing aluminum hydroxide micropowder, without aluminum loss or waste residue generation, significantly improving resource recycling efficiency.
[0040] As an optional embodiment, the step of obtaining a barium hydroxide solution having a set mass concentration specifically includes:
[0041] Barium hydroxide is mixed with a solvent having a set temperature to obtain a barium hydroxide solution having a set mass concentration.
[0042] In the above embodiment, since barium hydroxide is usually in a solid state, it needs to be first dissolved in a solvent to prepare a solution in order to perform the subsequent chemical precipitation reaction.
[0043] As an optional implementation manner, the set mass concentration is 30% to 50%.
[0044] In the above embodiment, the set mass concentration is controlled to be within the range of 30% to 50% because, when preparing the barium hydroxide solution, the higher the water temperature, the higher the solubility of barium hydroxide; when the water temperature is 80°C to 100°C, the solubility of barium hydroxide in water is within the range of 30% to 50%. Exemplarily, the set mass concentration may be 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 45%, 46%, 48% or 50%.
[0045] As an optional implementation manner, the set temperature is 80°C to 100°C.
[0046] In the above embodiment, the set temperature is controlled to be 80°C to 100°C in order to control the temperature of the solution, thereby ensuring that the barium hydroxide has a high solubility and dissolution rate in the solvent. Exemplarily, the set temperature can be 80°C, 82°C, 84°C, 85°C, 86°C, 88°C, 90°C, 92°C, 94°C, 95°C, 96°C, 98°C or 100°C.
[0047] As an optional embodiment, the mass ratio of the barium hydroxide to the carbonate in the sodium aluminate is 2.86:1 to 3.2:1.
[0048] In the above embodiment, the mass ratio of barium hydroxide to carbonate in the sodium aluminate solution is controlled to be between 2.86:1 and 3.2:1 because a mass ratio within this range can ensure that the barium hydroxide and carbonate react fully and rapidly. For example, the mass ratio of barium hydroxide to carbonate in the sodium aluminate solution can be 2.86:1, 2.9:1, 3.0:1, 3.1:1, or 3.2:1.
[0049] As an optional embodiment, the reaction temperature of the precipitation reaction is 70° C. to 95° C.; and the reaction time is 0.5 h to 2 h.
[0050] In the above embodiment, the reason why the temperature of the precipitation reaction is 70°C to 95°C is that the precipitation reaction rate is high within this temperature range. At the same time, since the temperatures of the sodium aluminate solution and the barium hydroxide solution are usually also within this range in actual production, no additional heating or cooling measures are required, thereby effectively saving energy. The time of the precipitation reaction is controlled to ensure that the carbonate ions can fully react with the barium hydroxide and improve the removal rate of the carbonate ions. Exemplarily, the reaction temperature of the precipitation reaction can be 50°C, 60°C, 70°C, 80°C, 90°C or 95°C, and the time of the precipitation reaction can be 0.5h, 0.8h, 1h, 1.2h, 1.5h, 1.8h or 2h, etc.
[0051] As an optional embodiment, the sodium aluminate solution satisfies at least one of the following conditions: the alkali concentration in the sodium aluminate solution is 20 g / L to 230 g / L, and the alumina concentration is 10 g / L to 240 g / L.
[0052] In the above embodiment, the reason for controlling the sodium aluminate solution to satisfy the alkali concentration of 20 g / L to 230 g / L and the alumina concentration of 10 g / L to 240 g / L is that, in the production of alumina, the concentration of alkali and the concentration of alumina in the sodium aluminate solution are basically within this range, so the method in the present application can be directly applied to the sodium aluminate solution produced in the production process of alumina.
[0053] As an optional embodiment, after the mixed solution is subjected to solid-liquid separation to obtain a refined sodium aluminate solution and a barium carbonate precipitate, the method further comprises:
[0054] S4, calcining and decarburizing the barium carbonate precipitate to obtain barium oxide solid;
[0055] S5. Mixing the barium oxide solid with a solvent to obtain a barium hydroxide solution with a set concentration.
[0056] In the above embodiment, the barium carbonate precipitate obtained by precipitation is calcined and decarbonized in step S4, which can decompose the barium carbonate into barium oxide and carbon dioxide, wherein the carbon dioxide is directly discharged, leaving only the barium oxide solid for use.
[0057] In step S5, after the barium oxide solid and the solvent are mixed, they can directly react to obtain barium hydroxide, and then the concentration is adjusted to obtain a barium hydroxide solution with a set concentration, and then circulated to step S1, thereby realizing the recycling of the remover.
[0058] In the above embodiment, the separated barium carbonate is decarbonized by high-temperature roasting to produce barium oxide. The residual heat from the high-temperature roasting is then used to directly dissolve the barium oxide, achieving high-temperature, high-concentration dissolution of the barium oxide without the need for external heat sources. The barium oxide is then hydrated to produce barium hydroxide, which is then recycled as a removal agent. This method reduces the cost of carbonate removal while conserving resources and energy. Sodium carbonate reacts with barium hydroxide to produce sodium hydroxide, which becomes a beneficial substance in aluminum hydroxide production and continues to be utilized, further reducing the cost of carbonate removal.
[0059] As an optional embodiment, the temperature of the roasting and decarburization is 1400°C to 1500°C.
[0060] In the above embodiment, the roasting decarburization temperature is controlled to be 1400°C to 1500°C because the decomposition of barium carbonate is achieved within this temperature range. Exemplarily, the roasting decarburization temperature can be 1400°C, 1410°C, 1420°C, 1430°C, 1440°C, 1450°C, 1460°C, 1470°C, 1480°C, 1490°C, or 1500°C.
[0061] As an optional embodiment, the solvent is water or a water analogue.
[0062] In the above embodiment, water or a water analogue is used as the solvent, which is low in cost and is less likely to introduce impurities into the sodium aluminate solution.
[0063] The present application is further described below with reference to specific examples. Experimental methods in the following examples where specific conditions are not specified are generally measured in accordance with national / industry standards. If there are no corresponding national / industry standards, the methods are carried out in accordance with commonly used international standards, conventional conditions, or conditions recommended by the manufacturer.
[0064] Examples 1 to 5 provide methods for removing carbonate from sodium aluminate solution with different parameters, as detailed below:
[0065] Example 1
[0066] This embodiment provides a method for removing carbonate ions from a sodium aluminate solution, comprising the following steps:
[0067] The N of the sodium aluminate solution in this embodiment k The value range is 190g / L(N k represents the concentration of caustic soda in sodium aluminate solution in terms of Na2O, in g / L), the alumina concentration is 240 g / L, and the CO3 before carbonate removal 2- The concentration is 30g / L;
[0068] S1, dissolving barium hydroxide in 80° C. water to obtain a barium hydroxide solution having a mass concentration of 30%;
[0069] S2, adding the barium hydroxide solution to the sodium aluminate solution redissolved in aluminum hydroxide to carry out a precipitation reaction to obtain a mixed solution including a precipitate;
[0070] Among them, the amount of barium hydroxide added is related to the carbonate (CO3 2- ) mass ratio is 2.9:1, the reaction temperature is 95 ° C, and the reaction time is 1h;
[0071] S3. After solid-liquid separation of the mixed solution, a refined sodium aluminate solution and barium carbonate precipitate are obtained.
[0072] After testing, the CO3 in the refined sodium aluminate solution 2- The concentration is 2.0g / L.
[0073] Example 2
[0074] This embodiment provides a method for removing carbonate ions from a sodium aluminate solution, comprising the following steps:
[0075] The N of the sodium aluminate solution in this embodiment kThe range of the value is 140g / L, the concentration of alumina is 165g / L, and the CO3 before removing carbonate 2- The concentration is 20g / L;
[0076] S1, dissolving barium hydroxide in water at 100° C. to obtain a barium hydroxide solution having a mass concentration of 50%;
[0077] S2, adding the barium hydroxide solution to the sodium aluminate solution redissolved in aluminum hydroxide to carry out a precipitation reaction to obtain a mixed solution including a precipitate;
[0078] Among them, the amount of barium hydroxide added is related to the carbonate (CO3 2- ) mass ratio is 3.0:1, the reaction temperature is 70 ° C, and the reaction time is 1.5h;
[0079] S3. After solid-liquid separation of the mixed solution, a refined sodium aluminate solution and barium carbonate precipitate are obtained.
[0080] After testing, the CO3 in the refined sodium aluminate solution 2- The concentration is 1.2g / L.
[0081] Example 3
[0082] This embodiment provides a method for removing carbonate ions from a sodium aluminate solution, comprising the following steps:
[0083] The N of the sodium aluminate solution in this embodiment k The value range is 150g / L, the alumina concentration is 75g / L, and the CO3 before removing carbonate 2- The concentration is 15g / L;
[0084] S1, dissolving barium hydroxide in 90° C. water to obtain a barium hydroxide solution having a mass concentration of 40%;
[0085] S2, adding the barium hydroxide solution to the sodium aluminate solution redissolved in aluminum hydroxide to perform a precipitation reaction to obtain a mixed solution including a precipitate;
[0086] Among them, the amount of barium hydroxide added is related to the carbonate (CO3 2- ) mass ratio is 2.86:1, the reaction temperature is 60 ° C, and the reaction time is 2h;
[0087] S3. After solid-liquid separation of the mixed solution, a refined sodium aluminate solution and barium carbonate precipitate are obtained.
[0088] After testing, the CO3 in the refined sodium aluminate solution 2- The concentration is 1.3g / L.
[0089] Example 4
[0090] This embodiment provides a method for removing carbonate ions from a sodium aluminate solution, comprising the following steps:
[0091] The N of the sodium aluminate solution in this embodiment k The range of the value is 100g / L, the concentration of alumina is 30g / L, and the CO3 before removing carbonate 2- The concentration is 5g / L;
[0092] S1, dissolving barium hydroxide in 90° C. water to obtain a barium hydroxide solution having a mass concentration of 45%;
[0093] S2, adding the barium hydroxide solution to the sodium aluminate solution redissolved in aluminum hydroxide to carry out a precipitation reaction to obtain a mixed solution including a precipitate;
[0094] Among them, the amount of barium hydroxide added is related to the carbonate (CO3 2- ) mass ratio is 2.9:1, the reaction temperature is 70 ° C, and the reaction time is 1.0h;
[0095] S3. After solid-liquid separation of the mixed solution, a refined sodium aluminate solution and barium carbonate precipitate are obtained.
[0096] After testing, the CO3 in the refined sodium aluminate solution 2- The concentration is 0.4g / L.
[0097] S4, calcining the obtained barium carbonate precipitate at 1450° C. to decarbonize and obtain barium oxide solid;
[0098] S5. Mixing the barium oxide solid with water to obtain a barium hydroxide solution that can be reused.
[0099] Example 5
[0100] This embodiment provides a method for removing carbonate ions from a sodium aluminate solution, comprising the following steps:
[0101] The N of the sodium aluminate solution in this embodiment k The range of the value is 30g / L, the concentration of alumina is 7g / L, and the CO3 before removing carbonate 2- The concentration is 3g / L;
[0102] S1, dissolving barium hydroxide in water at 100° C. to obtain a barium hydroxide solution having a mass concentration of 50%;
[0103] S2, adding the barium hydroxide solution to the sodium aluminate solution redissolved in aluminum hydroxide to carry out a precipitation reaction to obtain a mixed solution including a precipitate;
[0104] Among them, the amount of barium hydroxide added is related to the carbonate (CO3 2- ) mass ratio is 2.9:1, the reaction temperature is 85 ° C, and the reaction time is 1.5 h;
[0105] S3. After solid-liquid separation of the mixed solution, a refined sodium aluminate solution and barium carbonate precipitate are obtained.
[0106] After testing, the CO3 in the refined sodium aluminate solution 2- The concentration is 0.2g / L.
[0107] Comparative Example
[0108] This embodiment provides a method for removing carbonate ions from a sodium aluminate solution. The steps of this method are basically the same as those in Example 3, except that the barium hydroxide solution is replaced with calcium hydroxide slurry. The other steps remain unchanged. The specific contents are as follows:
[0109] The N of the sodium aluminate solution in this embodiment k The value range is 150g / L, where N k —Calculated as Na2O, the concentration of caustic soda in sodium aluminate solution, unit: g / L, the alumina concentration is 75g / L, CO3 before removing carbonate 2- The concentration of is 15g / L, and the concentration of calcium ions is 15ppm;
[0110] S1, adding a hydrated calcium hydroxide slurry having an effective calcium solid content of 180 g / L to a sodium aluminate solution redissolved in aluminum hydroxide to perform a precipitation reaction to obtain a mixed solution including a precipitate;
[0111] Among them, the amount of effective calcium hydroxide added is the amount of calcium hydroxide added to the carbonate (CO3 2- ) to complete 1.1 times the theoretical amount of the reaction, the reaction temperature is 90 ° C, and the reaction time is 2 h;
[0112] S2. After solid-liquid separation of the mixed solution, a refined sodium aluminate solution and calcium carbonate and calcium aluminate precipitates are obtained.
[0113] After testing, the CO3 in the refined sodium aluminate solution 2- The concentration is 3.5g / L, the aluminum oxide concentration is 51.5g / L, and the calcium ion concentration is 120ppm.
[0114] Compared with the refined sodium aluminate solution in Example 3, it can be seen that in the process of using calcium hydroxide as a remover to remove carbonate from the sodium aluminate solution in the comparative example, a small amount of calcium ions will be introduced, resulting in a large amount of calcium aluminate slag, an aluminum loss rate of 31.3%, and the carbonate removal rate is also significantly lower than the carbonate removal rate in Example 3.
[0115] In summary, the method for removing carbonate ions from sodium aluminate solution provided in the embodiment of the present application is to add barium hydroxide to the sodium aluminate solution, so that the carbonate ions and the barium hydroxide form insoluble barium carbonate solids, which are then removed after liquid-solid separation to obtain a refined sodium aluminate solution; after testing, in the alumina production process, through specific measures, CO3 in the solution is reduced. 2- The content can be effectively reduced to 0.2g / L to 2.0g / L, achieving a removal rate of over 90% while ensuring that no new impurities are introduced. Furthermore, the barium carbonate solid obtained after solid-liquid separation can be recycled after high-temperature roasting.
[0116] As can be seen from the above, this process is simple and easy to operate. The separated barium carbonate is decarbonized by high-temperature roasting to produce barium oxide. The waste heat from the high-temperature roasting is used to directly dissolve the barium oxide, achieving high-temperature, high-concentration dissolution of the barium oxide without external heat source heating. The barium oxide is hydrated to produce barium hydroxide, which is recycled as a removal agent. This method not only reduces the cost of carbonate removal but also saves resources and energy. Sodium carbonate reacts with barium hydroxide to produce sodium hydroxide, which becomes a beneficial substance in aluminum hydroxide production and continues to be utilized, further reducing the cost of carbonate removal.
[0117] This method can obtain a sodium aluminate solution with a low carbonate concentration, eliminates the influence of carbonate on the production of aluminum hydroxide by the redissolution method, and makes the production of aluminum hydroxide and the product quality more stable and the purity higher; compared with the existing carbonate removal process, there is no aluminum loss, no waste residue generation, and a high resource recycling rate.
[0118] The foregoing is merely a detailed description of the present invention, intended to enable those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but rather is intended to conform to the broadest scope consistent with the principles and novel features claimed herein.
Claims
1. A method for removing carbonate ions from a sodium aluminate solution, characterized in that: The method comprises the following steps: Obtaining a barium hydroxide solution with a set mass concentration; adding the barium hydroxide solution to the sodium aluminate solution so that the barium hydroxide reacts with the carbonate in the sodium aluminate solution to produce a precipitation reaction, thereby obtaining a mixed solution including a precipitate; performing solid-liquid separation on the mixed solution to obtain a refined sodium aluminate solution and a barium carbonate precipitate; The set mass concentration is 20% to 50%; The mass ratio of the barium hydroxide to the carbonate in the sodium aluminate solution is 2.5:1 to 3.5:
1.
2. The method according to claim 1, characterized in that The method of obtaining a barium hydroxide solution having a set mass concentration specifically comprises: Barium hydroxide is mixed with a solvent having a set temperature to obtain a barium hydroxide solution having a set mass concentration.
3. The method according to claim 2, characterized in that The set temperature is 80°C to 100°C.
4. The method according to claim 1 or 2, characterized in that The set mass concentration is 30% to 50%.
5. The method according to claim 1, characterized in that The mass ratio of the barium hydroxide to the carbonate in the sodium aluminate solution is 2.86:1 to 3.2:
1.
6. The method according to claim 1, characterized in that The reaction temperature of the precipitation reaction is 70° C. to 95° C.; the reaction time of the precipitation reaction is 0.5 h to 2 h.
7. The method according to claim 1, characterized in that The alkali concentration in the sodium aluminate solution is 20 g / L to 230 g / L, and the aluminum oxide concentration is 10 g / L to 240 g / L.
8. The method according to claim 1, characterized in that The mixed solution is subjected to solid-liquid separation to obtain a refined sodium aluminate solution and a barium carbonate precipitate, and the method further comprises: calcining and decarbonizing the barium carbonate precipitate to obtain barium oxide solid; The barium oxide solid is mixed with a solvent to obtain a barium hydroxide solution with a set concentration.
9. The method according to claim 7, characterized in that The temperature of the roasting and decarburization is 1400°C to 1500°C.
10. The method according to claim 2 or 7, characterized in that The solvent is water.