Method for co-producing pseudo-boehmite and amorphous alumina

Abstract

The invention relates to the technical field of aluminum oxide preparation, in particular to a method for co-producing pseudo-boehmite and amorphous aluminum oxide. The method comprises the following steps: carrying out neutralization reaction on carbon dioxide and a sodium aluminate solution to obtain neutralized slurry containing sodium carbonate and aluminum hydroxide colloidal particles; carrying out aging treatment on the neutralized slurry, so that the aluminum hydroxide colloidal particles form pseudo-boehmite crystals under the action of sodium carbonate, and obtaining aged slurry; filtering the aged slurry to obtain a solid-phase material and a liquid-phase material containing sodium carbonate; sequentially washing and drying the solid-phase material to obtain a pseudo-boehmite product; carrying out double hydrolysis reaction on the liquid-phase material to obtain hydrolyzed slurry containing amorphous alumina; and carrying out post-treatment on the hydrolyzed slurry to obtain the amorphous alumina.

Description

Technical Field

[0001] The present application relates to the technical field of alumina preparation, and in particular to a method for co-producing pseudo-boehmite and amorphous alumina. Background Art

[0002] Traditional alumina industrial production mainly adopts two process routes: carbonization and neutralization. In the carbonization process, sodium aluminate solution can be used to prepare pseudo-boehmite through carbonation reaction. In this process, a large amount of strong alkaline washing waste liquid (pH>11) will be produced, the main components of which are residual sodium carbonate and nano-scale pseudo-boehmite colloidal particles. These strong alkaline washing waste liquids have strong alkalinity and high colloidal stability. Difficulties in treatment. In comparison, the neutralization method synthesizes aluminum hydroxide precursors through the hydrolysis and precipitation reaction of aluminum salts (such as aluminum sulfate, aluminum chloride) and alkaline precipitants (such as ammonia water, urea). Although this process has the advantages of mild reaction conditions, easy-to-control operating parameters, and high product purity, and the product performance can be flexibly controlled by adjusting the reaction conditions, the neutralization method is subject to the high cost of alkaline reagents, and its industrial application is significantly restricted.

[0003] At present, the alkaline reagent of the neutralization method can be replaced by the strong alkaline washing waste liquid produced by the carbon separation method to produce pseudo-boehmite, and the strong alkaline washing waste liquid can be used as the alkali source for neutralizing the acid solution containing aluminum ions to reduce the cost of preparing alumina by the neutralization method. This coupling system of the carbon separation method and the neutralization method can not only achieve the synergistic co-production of pseudo-boehmite and alumina products, but also achieve dual environmental and economic benefits: on the one hand, this coupling system can effectively absorb the high-alkaline wastewater generated by the carbon separation method in the production of pseudo-boehmite, solving the environmental management problems faced by traditional processes; on the other hand, this coupling system can greatly reduce the dependence of the neutralization method on commercial alkaline reagents, significantly improving the economic efficiency of the co-production process.

[0004] However, in the process of using the strong alkaline washing waste liquid from the carbon fractionation method to replace the alkaline reagent of the neutralization method to produce pseudo-boehmite, the strong alkaline washing liquid contains a large amount of impurities, which can easily cause the purity of the aluminum oxide produced by the neutralization method to be low. At the same time, the aluminum oxide grains of the neutralization method will affect the crystallinity of the pseudo-boehmite produced by the carbon fractionation method. Summary of the Invention

[0005] The present application provides a method for co-producing pseudo-boehmite and amorphous alumina to solve the following technical problem: how to simultaneously improve the crystallinity of pseudo-boehmite co-produced by carbon separation and neutralization methods and the purity of alumina products.

[0006] In a first aspect, embodiments of the present application provide a method for co-producing pseudo-boehmite and amorphous alumina, the method comprising:

[0007] neutralizing carbon dioxide and sodium aluminate solution to obtain a neutralized slurry containing sodium carbonate and aluminum hydroxide colloid particles;

[0008] aging the neutralized slurry containing sodium carbonate and aluminum hydroxide colloid particles so that the aluminum hydroxide colloid particles form pseudo-boehmite crystals under the action of sodium carbonate, thereby obtaining an aged slurry;

[0009] filtering the aged slurry to obtain a solid phase material and a liquid phase material containing sodium carbonate;

[0010] washing and drying the solid phase material in sequence to obtain a pseudo-boehmite product;

[0011] performing a double hydrolysis reaction on the aluminum-containing solution and the liquid phase material containing sodium carbonate to obtain a hydrolysis slurry containing amorphous aluminum oxide;

[0012] The hydrolysis slurry containing amorphous aluminum oxide is post-treated to obtain amorphous aluminum oxide.

[0013] Optionally, the volume V1 of the aluminum-containing solution and the volume V2 of the liquid phase material satisfy: V1:V2=(15 to 30):1.

[0014] Optionally, the aluminum oxide content of the aluminum-containing solution is 50 g / L to 110 g / L; and / or

[0015] The aluminum-containing solution may be selected from at least one of the following: aluminum sulfate, aluminum nitrate, and aluminum chloride.

[0016] Optionally, the pH of the neutralized slurry is 9.5 to 12.5.

[0017] Optionally, the neutralization reaction temperature is 40°C to 60°C; and / or

[0018] The temperature of the aging treatment is 50° C. to 80° C., and the time of the aging treatment is 1 hour to 4 hours.

[0019] Optionally, the temperature of the double hydrolysis reaction is 25°C to 70°C.

[0020] Optionally, the target pH of the double hydrolysis reaction is 5.0 to 7.0.

[0021] Optionally, the post-processing of the hydrolysis slurry containing amorphous aluminum oxide to obtain amorphous aluminum oxide comprises the following steps:

[0022] performing solid-liquid separation on the hydrolyzed slurry containing amorphous alumina to obtain a hydrolyzed solid phase material;

[0023] The hydrolyzed solid phase material is washed and dried in sequence to obtain amorphous aluminum oxide.

[0024] Optionally, the aluminum oxide content of the sodium aluminate solution is 50 g / L to 110 g / L; the sodium oxide content of the sodium aluminate solution is 60 g / L to 100 g / L.

[0025] Optionally, the sodium oxide content of the amorphous alumina is ≤2.0%, and the impurity content of the amorphous alumina is ≤2.0%; and the crystallinity of the pseudo-boehmite product is 76.5% to 81.1%.

[0026] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0027] An embodiment of the present application provides a method for co-producing pseudo-boehmite and amorphous alumina. The method first uses carbon dioxide and sodium aluminate solution to carry out a neutralization reaction to generate a neutralized slurry containing aluminum hydroxide colloid and a large amount of sodium carbonate. Then, through an aging treatment, the formed aluminum hydroxide colloid can be directionally converted into pseudo-boehmite crystals. These pseudo-boehmite crystals can be used to obtain a solid phase material containing pseudo-boehmite crystals and a liquid phase material rich in sodium carbonate through solid-liquid separation; then, the liquid phase material containing sodium carbonate is used to replace the alkaline reagent used in the neutralization method, and through a double hydrolysis reaction between the aluminum-containing solution and the liquid phase material containing sodium carbonate, the aluminum ions in the aluminum-containing solution can be induced to precipitate toward the aluminum hydroxide to form amorphous alumina crystals. These amorphous alumina crystals can be formed into an amorphous alumina product through post-treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] 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.

[0029] 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.

[0030] Figure 1 A schematic flow chart of a method for co-producing pseudo-boehmite and amorphous alumina provided in an embodiment of the present application;

[0031] Figure 2 A detailed flow chart of a method for co-producing pseudo-boehmite and amorphous alumina provided in an embodiment of the present application. DETAILED DESCRIPTION

[0032] 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.

[0033] The range descriptions described in this application, 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" and "including" 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 simultaneously; 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 text, 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.

[0034] Figure 1 A schematic flow chart of a method for co-producing pseudo-boehmite and amorphous alumina provided in an embodiment of the present application is shown as an example;

[0035] like Figure 1 As shown, the embodiment of the present application provides a method for co-producing pseudo-boehmite and amorphous alumina, the method comprising:

[0036] S1. The carbon dioxide and sodium aluminate solution are neutralized to obtain a neutralized slurry containing sodium carbonate and aluminum hydroxide colloids;

[0037] S2. The neutralized slurry containing sodium carbonate and aluminum hydroxide colloid is aged so that the aluminum hydroxide colloid forms pseudo-boehmite crystals under the action of sodium carbonate to obtain an aged slurry;

[0038] S3. The aged slurry is filtered to obtain a solid material and a liquid material containing sodium carbonate;

[0039] S4. The solid phase material is sequentially washed and dried to obtain a pseudo-boehmite product;

[0040] S5. The aluminum-containing solution and the liquid phase material containing sodium carbonate are subjected to a double hydrolysis reaction to obtain a hydrolyzed slurry containing amorphous alumina;

[0041] S6. Post-treating the hydrolysis slurry containing amorphous aluminum oxide to obtain amorphous aluminum oxide.

[0042] It should be noted that the method for co-producing pseudo-boehmite and amorphous alumina provided in the examples of this application achieves the goal of simultaneously improving the crystallinity of pseudo-boehmite produced by carbonization and the purity of amorphous alumina produced by double hydrolysis through carbonization process design and material recycling. Its core mechanism lies in the following aspects:

[0043] 1. Optimize the crystallinity of carbon fractionation (pseudo-boehmite segment):

[0044] (1) Precise control of neutralization and aging: Using CO2 to neutralize sodium aluminate solution is more gentle than strong acid neutralization, and the initial aluminum hydroxide gel particles generated are more uniform and smaller, providing a good foundation for subsequent aging and crystallization.

[0045] (2) Key aging treatment: The neutralized slurry is aged at a specific temperature and time to dissolve and recrystallize the initially formed amorphous or low-crystallinity aluminum hydroxide particles. During this process, smaller, unstable particles dissolve, and aluminate ions re-deposit and grow on larger, more stable crystal nuclei, promoting the directional growth and development of pseudo-boehmite crystals, thereby improving their crystallinity and grain integrity.

[0046] (3) Effectively wash the solid phase material: The solid phase material (mainly containing pseudo-boehmite) obtained by filtration after aging is fully washed to significantly reduce the sodium ion (Na + ) and other impurities. Insufficient washing can cause sodium salts to be encapsulated or adsorbed on the surface or interior of the particles, reducing purity and disrupting the crystal structure during subsequent calcination, affecting the crystallinity and strength of the final alumina. Effective washing is key to obtaining highly crystalline, high-purity pseudo-boehmite.

[0047] 2. Use liquid phase materials (double hydrolysis stage) to improve purity and resource utilization:

[0048] (1) Properties of the liquid phase: The liquid phase (mother liquor) obtained after carbon separation filtration is mainly composed of sodium carbonate (Na2CO3) and a small amount of residual sodium aluminate NaAlO2. If this part of aluminum is not recycled, it will result in a waste of aluminum resources. More importantly, if this part of the mother liquor is directly recycled back to the carbon separation system, the carbonate and sodium ions in it will continue to accumulate, resulting in an increase in impurity concentration, which will seriously affect the crystallinity and purity of the subsequent carbon separation products.

[0049] (2) Double hydrolysis reaction to remove impurities and purify:

[0050] 1) Introducing an aluminum-containing solution: usually an acidic aluminum salt solution (such as aluminum sulfate, aluminum chloride, aluminum nitrate, etc.) or a sodium metaaluminate solution.

[0051] 2) Reaction mechanism: When the acidic aluminum salt solution (providing Al 3+ and H + ) is mixed with an alkaline liquid phase material rich in sodium carbonate and a small amount of sodium aluminate, a violent double hydrolysis reaction occurs:

[0052] Al 3+ +3H2O→Al(OH)3↓+3H + (aluminum salt hydrolysis);

[0053] CO3 2- +2H + →H2O+CO2↑(carbonate hydrolysis);

[0054] Residual Al(OH)4 - +H + →Al(OH)3↓+H2O;

[0055] (3) Impurity removal: During the double hydrolysis reaction, carbonate ions are completely consumed: sodium carbonate is reacted with H + It is neutralized, converted into CO2 gas and escaped, and completely removed from the system, thus avoiding the circulation and accumulation of carbonate ions in the system.

[0056] 1) Precipitation of residual aluminum: The residual sodium aluminate in the liquid phase is also converted into aluminum hydroxide precipitate (amorphous alumina precursor).

[0057] 2) Removal of sodium: After the reaction, sodium ions (Na + ) exists in the liquid phase of the hydrolysis slurry in the form of neutral salts (such as Na2SO4, NaCl, NaNO3). These sodium salts are generally highly soluble in water.

[0058] (4) Purification: Through subsequent post-treatment (filtration and washing) of the hydrolysis slurry, the precipitated amorphous aluminum hydroxide (i.e., amorphous alumina precursor) can be efficiently separated from the filtrate containing soluble sodium salts. Sufficient washing can maximize the removal of sodium salts adsorbed on the surface of amorphous particles, thereby significantly improving the purity of the final amorphous alumina product.

[0059] 3. Synergy: The key to synchronous improvement:

[0060] (1) Breaking the impurity cycle: This is the core synergy point. One of the biggest problems of the traditional carbon separation method is that the mother liquor circulation leads to the accumulation of carbonate and sodium ions, which deteriorates the product quality. This method introduces the carbon separation mother liquor (liquid phase material) into a double hydrolysis reaction, converting the accumulated and harmful carbonate into CO2 gas and exhausting it from the system, and converting the sodium into salts that are easily soluble in water, which are effectively removed when washing the amorphous alumina. This fundamentally cuts off the circulation and accumulation path of impurities in the carbon separation system.

[0061] (2) Purification of the carbonization raw material environment: Since the liquid phase material is drawn out and disposed of, it is no longer recycled back to the carbonization system in large quantities (or even if it is recycled in small quantities, the impurity concentration has been greatly reduced), making the sodium aluminate solution environment for the carbonization reaction purer. Reducing the impurity concentration creates favorable conditions for the neutralization reaction to produce more uniform initial particles and the aging process to achieve more perfect crystal growth, thereby simultaneously improving the crystallinity and purity of the pseudo-boehmite.

[0062] (3) Efficient utilization of resources: The residual aluminum in the liquid phase material is effectively recovered by the double hydrolysis reaction and converted into valuable amorphous alumina products, thereby improving the overall utilization rate of aluminum resources.

[0063] (4) Complementary product characteristics: The double hydrolysis reaction is carried out under acidic conditions and tends to produce amorphous aluminum hydroxide, which just meets the requirements of amorphous alumina products. The carbonization and aging processes are optimized under alkaline conditions, which is conducive to the formation of pseudo-boehmite crystals.

[0064] Therefore, the key to the method for co-producing pseudo-boehmite and amorphous alumina provided in the embodiments of the present application and simultaneously improving the quality of the two products lies in:

[0065] (1) Optimize the carbonization and aging processes (mild CO2 neutralization, precise aging, and sufficient washing) to directly improve the crystallinity and purity of pseudo-boehmite.

[0066] (2) The mother liquor (liquid phase material) rich in sodium carbonate and residual aluminum produced by the carbon fraction is introduced into a double hydrolysis reaction.

[0067] (3) The core role of the double hydrolysis reaction is:

[0068] 1) Convert the accumulated carbonate into CO2 and completely discharge it from the system.

[0069] 2) Recycling residual aluminum into products.

[0070] 3) Convert sodium into soluble salts.

[0071] (4) By efficiently separating and washing the double hydrolysis product (amorphous alumina), soluble impurities such as sodium salt are removed to improve its purity.

[0072] (5) Synergistic effect: The double hydrolysis treatment of the mother liquor cuts off the cyclic accumulation of impurities (especially carbonate) in the carbonization system, creating a purer reaction environment for the carbonization-aging process, thereby indirectly but significantly improving the crystallinity and purity of pseudo-boehmite, while also producing high-purity amorphous alumina.

[0073] In summary, the embodiments of the present application provide a method for the co-production of pseudo-boehmite and amorphous alumina. This method solves the problem of impurity accumulation in traditional single processes through material flow design and chemical reaction coupling, and achieves the co-production of two high-value-added alumina products and the simultaneous improvement of their quality.

[0074] In some optional embodiments, the volume V1 of the aluminum-containing solution and the volume V2 of the liquid phase material satisfy:

[0075] V1:V2=(15 to 30):1.

[0076] In these embodiments, a double hydrolysis reaction can be fully carried out between the aluminum-containing solution and the liquid material in a volume ratio of (15 to 30):1. Through the action of sodium carbonate in the liquid material, the aluminum ions in the aluminum-containing solution will form amorphous aluminum hydroxide, which is conducive to the subsequent formation of high-purity amorphous alumina products.

[0077] The volume V1 of the aluminum-containing solution can be 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30.

[0078] In some optional embodiments, the aluminum-containing solution has an aluminum oxide content of 50 g / L to 110 g / L; and / or

[0079] The aluminum-containing solution may be selected from at least one of the following: aluminum sulfate, aluminum nitrate, and aluminum chloride.

[0080] In these embodiments, an aluminum-containing solution having an aluminum oxide content of 50 g / L to 110 g / L can provide the aluminum-containing solution with sufficient aluminum ion components. These aluminum ion components undergo a double hydrolysis reaction with the alkaline liquid phase material to form uniformly dispersed and high-purity amorphous aluminum oxide. Furthermore, using an aluminum-containing solution comprising at least one of aluminum sulfate, aluminum nitrate, and aluminum chloride can cover most types of aluminum-containing solutions, allowing the aluminum-containing solution to fully undergo a double hydrolysis reaction with the alkaline liquid phase material to form uniformly dispersed and high-purity amorphous aluminum oxide.

[0081] The aluminum oxide content of the aluminum-containing solution may be 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L, or 110 g / L.

[0082] It should be noted that the aluminum-containing solution is not a specific aluminum oxide product. Its essence is various substances in the form of aluminum oxide (such as aluminum hydroxide).

[0083] In some optional embodiments, the pH of the neutralized slurry is 9.5 to 12.5.

[0084] In these embodiments, a neutralized slurry having a pH of 9.5 to 12.5 may indicate that the slurry contains sufficient sodium carbonate and other alkaline components to ensure that the amorphous aluminum hydroxide in the neutralized slurry forms a pseudo-boehmite product in the subsequent aging treatment stage.

[0085] The pH of the neutralized slurry may be 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, or 12.5.

[0086] In some optional embodiments, the temperature of the neutralization reaction is 40°C to 60°C; and / or

[0087] The temperature of the aging treatment is 50° C. to 80° C., and the time of the aging treatment is 1 hour to 4 hours.

[0088] In these embodiments, a neutralization reaction at a temperature of 40°C to 60°C allows the carbon dioxide gas to fully react with the sodium aluminate solution to form a neutralized slurry containing sodium carbonate and aluminum hydroxide colloidal particles. Furthermore, an aging treatment at a temperature of 50°C to 80°C for 1 to 4 hours allows the aluminum hydroxide colloidal particles in the neutralized slurry to form pseudo-boehmite crystals under the action of sodium carbonate, facilitating the subsequent formation of a high-purity pseudo-boehmite product.

[0089] The temperature of the neutralization reaction may be 40°C, 45°C, 50°C, 55°C or 60°C.

[0090] The temperature of the aging treatment may be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C.

[0091] The aging treatment time can be 1 hour, 1.5 hours, 2.0 hours, 2.5 hours, 3.0 hours, 3.5 hours or 4.0 hours.

[0092] In some optional embodiments, the temperature of the double hydrolysis reaction is 25°C to 70°C.

[0093] In these embodiments, the double hydrolysis reaction at a temperature of 25°C to 70°C can allow the aluminum-containing solution and the sodium carbonate contained in the liquid phase material to fully react to form a hydrolysis slurry containing a large amount of amorphous aluminum oxide, thereby obtaining a high-purity amorphous aluminum oxide product.

[0094] The temperature of the double hydrolysis reaction can be 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, or 70°C.

[0095] In some optional embodiments, the target pH of the double hydrolysis reaction is 5.0 to 7.0.

[0096] In these embodiments, the double hydrolysis reaction with a target pH of 5.0 to 7.0 can indicate that the reaction between the aluminum-containing solution and the sodium carbonate in the liquid phase material in the double hydrolysis reaction has been fully carried out, thereby obtaining a hydrolysis slurry containing a large amount of amorphous aluminum oxide.

[0097] Figure 2 The following is a schematic diagram showing a detailed process of a method for co-producing pseudo-boehmite and amorphous alumina provided in an embodiment of the present application.

[0098] In some optional embodiments, such as Figure 2 As shown, the post-treatment of the hydrolysis slurry containing amorphous aluminum oxide to obtain amorphous aluminum oxide comprises the following steps:

[0099] S601. The hydrolyzed slurry containing amorphous alumina is subjected to solid-liquid separation to obtain a hydrolyzed solid phase material;

[0100] S602. Wash and dry the hydrolyzed solid phase material in sequence to obtain amorphous aluminum oxide.

[0101] In these embodiments, the hydrolysis slurry containing amorphous alumina is first subjected to solid-liquid separation to separate the crude amorphous alumina in the hydrolysis slurry, and then the separated crude amorphous alumina is washed and dried to effectively remove impurities in the crude amorphous alumina, thereby obtaining a high-purity amorphous alumina product.

[0102] In some optional embodiments, the aluminum oxide content of the sodium aluminate solution is 50 g / L to 110 g / L; the sodium oxide content of the sodium aluminate solution is 60 g / L to 100 g / L.

[0103] In these embodiments, a sodium aluminate solution having an aluminum oxide content of 50 g / L to 110 g / L and a sodium oxide content of 60 g / L to 100 g / L can be formed into a neutralized slurry containing sodium carbonate and aluminum hydroxide colloidal particles under the action of carbon dioxide.

[0104] The alumina content of the sodium aluminate solution may be 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L or 110 g / L.

[0105] The sodium aluminate solution may have a sodium oxide content of 60 g / L, 65 g / L, 70 g / L, 75 g / L, 80 g / L, 85 g / L, 90 g / L, 95 g / L, or 100 g / L.

[0106] In some optional embodiments, the sodium oxide content of the amorphous alumina is ≤2.0%, the impurity content of the amorphous alumina is ≤2.0%, and the crystallinity of the pseudo-boehmite product is 76.5% to 81.1%.

[0107] In these embodiments, the amorphous alumina having a sodium oxide content of ≤2.0% and an impurity content of ≤2.0% indicates that the amorphous alumina obtained by the method has high purity. In addition, the pseudo-boehmite product having a crystallinity of 76.5% to 81.1% indicates that the pseudo-boehmite product obtained by the method has good crystallinity.

[0108] The pseudo-boehmite product may have a crystallinity of 76.5%, 77.0%, 77.5%, 78.0%, 78.5%, 79.0%, 79.5%, 80.0%, 80.5%, 81.0% or 80.1%.

[0109] 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.

[0110] Example 1

[0111] like Figure 2 As shown, a method for co-producing pseudo-boehmite and amorphous alumina comprises:

[0112] S1. The carbon dioxide and sodium aluminate solution are neutralized to obtain a neutralized slurry containing sodium carbonate and aluminum hydroxide colloids;

[0113] S2. The neutralized slurry containing sodium carbonate and aluminum hydroxide colloid is aged, so that the aluminum hydroxide colloid forms pseudo-boehmite crystals under the action of sodium carbonate to obtain an aged slurry;

[0114] S3. The aged slurry was filtered to obtain a solid material and a liquid material containing sodium carbonate;

[0115] S4. The solid phase material is sequentially washed and dried to obtain a pseudo-boehmite product;

[0116] S5. The aluminum-containing solution and the liquid phase material containing sodium carbonate are subjected to a double hydrolysis reaction to obtain a hydrolysis slurry containing amorphous alumina;

[0117] S601. The hydrolyzed slurry containing amorphous alumina is subjected to solid-liquid separation to obtain a hydrolyzed solid phase material;

[0118] S602. Wash and dry the hydrolyzed solid phase material in sequence to obtain amorphous aluminum oxide.

[0119] The volume V1 of the aluminum-containing solution and the volume V2 of the liquid phase material satisfy: V1:V2=15:1.

[0120] The aluminum oxide content of the aluminum-containing solution is 70 g / L.

[0121] The type of aluminum-containing solution is aluminum sulfate.

[0122] The pH of the neutralized slurry was 9.8.

[0123] The temperature of the neutralization reaction is 40°C;

[0124] The aging treatment temperature is 60°C and the aging treatment time is 2.5 h.

[0125] The temperature of the double hydrolysis reaction was 25°C.

[0126] The target pH for the double hydrolysis reaction was 6.0.

[0127] The aluminum oxide content of the sodium aluminate solution is 50 g / L; the sodium oxide content of the sodium aluminate solution is 60 g / L.

[0128] Example 2

[0129] Compared with Example 1, this embodiment has the following differences, and the rest are the same:

[0130] The volume V1 of the aluminum-containing solution and the volume V2 of the liquid phase material satisfy: V1:V2=30:1.

[0131] The aluminum oxide content of the aluminum-containing solution is 50 g / L.

[0132] The type of aluminum-containing solution is aluminum nitrate.

[0133] The pH of the neutralized slurry was 10.5.

[0134] The temperature of the neutralization reaction is 50°C;

[0135] The aging temperature is 70°C and the aging time is 2 h.

[0136] The temperature of the double hydrolysis reaction was 40°C.

[0137] The target pH for the double hydrolysis reaction was 5.5.

[0138] The aluminum oxide content of the sodium aluminate solution is 70 g / L; the sodium oxide content of the sodium aluminate solution is 75 g / L.

[0139] Example 3

[0140] Compared with Example 1, this embodiment has the following differences, and the rest are the same:

[0141] The volume V1 of the aluminum-containing solution and the volume V2 of the liquid phase material satisfy: V1:V2=20:1.

[0142] The aluminum oxide content of the aluminum-containing solution was 110 g / L.

[0143] The type of aluminum-containing solution is aluminum chloride.

[0144] The pH of the neutralized slurry was 11.5.

[0145] The temperature of the neutralization reaction is 60°C;

[0146] The aging temperature is 50°C and the aging time is 4 hours.

[0147] The temperature of the double hydrolysis reaction was 60°C.

[0148] The target pH for the double hydrolysis reaction was 6.5.

[0149] The aluminum oxide content of the sodium aluminate solution is 90 g / L; the sodium oxide content of the sodium aluminate solution is 85 g / L.

[0150] Example 4

[0151] Compared with Example 1, this embodiment has the following differences, and the rest are the same:

[0152] The volume V1 of the aluminum-containing solution and the volume V2 of the liquid phase material satisfy: V1:V2=25:1.

[0153] The aluminum oxide content of the aluminum-containing solution is 80 g / L.

[0154] The type of aluminum-containing solution is aluminum chloride.

[0155] The pH of the neutralized slurry was 9.5.

[0156] The temperature of the neutralization reaction is 45°C;

[0157] The aging treatment temperature is 80°C, and the aging treatment time is 1.5 h.

[0158] The temperature of the double hydrolysis reaction was 70°C.

[0159] The target pH for the double hydrolysis reaction was 7.0.

[0160] The aluminum oxide content of the sodium aluminate solution is 60 g / L; the sodium oxide content of the sodium aluminate solution is 65 g / L.

[0161] Example 5

[0162] Compared with Example 1, this embodiment has the following differences, and the rest are the same:

[0163] The volume V1 of the aluminum-containing solution and the volume V2 of the liquid phase material satisfy: V1:V2=30:1.

[0164] The aluminum oxide content of the aluminum-containing solution was 90 g / L.

[0165] The type of aluminum-containing solution is aluminum sulfate.

[0166] The pH of the neutralized slurry was 12.5.

[0167] The temperature of the neutralization reaction is 55°C;

[0168] The aging treatment temperature is 75°C and the aging treatment time is 2.5 h.

[0169] The temperature of the double hydrolysis reaction was 25°C.

[0170] The target pH for the double hydrolysis reaction was 5.0.

[0171] The aluminum oxide content of the sodium aluminate solution is 110 g / L; the sodium oxide content of the sodium aluminate solution is 95 g / L.

[0172] Comparative Example 1

[0173] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0174] Instead of using liquid materials as alkaline reagents, commercial sodium carbonate reagents are directly used.

[0175] Comparative Example 2

[0176] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0177] The volume V1 of the aluminum-containing solution and the volume V2 of the liquid phase material satisfy: V1:V2=10:1.

[0178] Comparative Example 3

[0179] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0180] The volume V1 of the aluminum-containing solution and the volume V2 of the liquid phase material satisfy: V1:V2=40:1.

[0181] Comparative Example 4

[0182] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0183] The temperature of the double hydrolysis reaction was 20°C.

[0184] Comparative Example 5

[0185] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0186] The temperature of the double hydrolysis reaction was 80°C.

[0187] Related experiments and effect data:

[0188] The purity or crystallinity of the products obtained in each embodiment and comparative example were statistically analyzed, and the results are shown in Table 1.

[0189] Table 1 Purity or crystallinity of products obtained in various examples and comparative examples

[0190]

[0191] As can be seen from Table 1, the embodiment of the present application provides a method for co-producing pseudo-boehmite and amorphous alumina. This method achieves the goal of simultaneously improving the crystallinity of pseudo-boehmite produced by carbon separation and the purity of amorphous alumina produced by double hydrolysis through carbon separation process design and material recycling. Ultimately, an amorphous alumina product with an impurity ion content of less than 2.0% and a sodium oxide content of less than 2.0% can be obtained. At the same time, a pseudo-boehmite product with a crystallinity between 76.5% and 81.1% can be obtained.

[0192] Compared with Example 1, Comparative Example 1 directly uses commercial sodium carbonate reagent, and the purity of the amorphous aluminum oxide product finally obtained is lower.

[0193] Compared with Example 1, Comparative Example 2 uses less aluminum-containing solution, which results in insufficient consumption of alkaline liquid materials and waste of resources. Comparative Example 3 uses more aluminum-containing solution, which results in a higher impurity ion content in the subsequent amorphous alumina product.

[0194] Compared with Example 1, Comparative Example 4 uses a lower temperature double hydrolysis reaction, which results in a lower yield of the final amorphous alumina and a higher content of sodium oxide, etc.; while Comparative Example 5 uses a higher temperature double hydrolysis reaction, which results in a higher sodium oxide content in the final amorphous alumina.

[0195] In summary, the embodiments of the present application provide a method for the co-production of pseudo-boehmite and amorphous alumina. This method solves the problem of impurity accumulation in traditional single processes through material flow design and chemical reaction coupling, and achieves the co-production of two high-value-added alumina products and the simultaneous improvement of their quality.

[0196] In addition, an embodiment of the present application provides a method for co-producing pseudo-boehmite and amorphous alumina. This method uses the alkaline material of the pseudo-boehmite obtained by the carbon separation method as the alkali source for the neutralization method to achieve the co-production of pseudo-boehmite and amorphous alumina. This method can break through the bottleneck of waste liquid resource utilization, reduce the production cost of the neutralization method, and form a multi-form co-production system of aluminum resources, which has both environmental and economic benefits and promotes the clean production upgrade of the alumina industry.

[0197] In addition, the embodiments of the present application provide a method for co-producing pseudo-boehmite and amorphous alumina. This method can produce 0.18 to 0.36 tons of amorphous alumina products for every ton of pseudo-boehmite produced, which can significantly improve the utilization rate of aluminum resources.

[0198] 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 co-producing pseudo-boehmite and amorphous alumina, the method comprising: neutralizing carbon dioxide and sodium aluminate solution to obtain a neutralized slurry containing sodium carbonate and aluminum hydroxide colloid particles; aging the neutralized slurry containing sodium carbonate and aluminum hydroxide colloid particles so that the aluminum hydroxide colloid particles form pseudo-boehmite crystals under the action of sodium carbonate, thereby obtaining an aged slurry; filtering the aged slurry to obtain a solid phase material and a liquid phase material containing sodium carbonate; washing and drying the solid phase material in sequence to obtain a pseudo-boehmite product; performing a double hydrolysis reaction on the aluminum-containing solution and the liquid phase material containing sodium carbonate to obtain a hydrolysis slurry containing amorphous aluminum oxide; The hydrolysis slurry containing amorphous aluminum oxide is post-treated to obtain amorphous aluminum oxide.

2. The method according to claim 1, characterized in that The volume V1 of the aluminum-containing solution and the volume V2 of the liquid phase material satisfy: V1:V2=(15 to 30):

1.

3. The method according to claim 1 or 2, characterized in that The aluminum-containing solution has an aluminum oxide content of 50 g / L to 110 g / L; and / or The aluminum-containing solution may be selected from at least one of the following: aluminum sulfate, aluminum nitrate, and aluminum chloride.

4. The method according to claim 1, wherein The pH of the neutralized slurry is 9.5 to 12.

5.

5. The method according to claim 1, wherein The neutralization reaction temperature is 40°C to 60°C; and / or The temperature of the aging treatment is 50° C. to 80° C., and the time of the aging treatment is 1 hour to 4 hours.

6. The method according to claim 1, characterized in that The temperature of the double hydrolysis reaction is 25°C to 70°C.

7. The method according to claim 1, characterized in that The target pH of the double hydrolysis reaction is 5.0 to 7.

0.

8. The method according to claim 1, characterized in that The post-processing of the hydrolysis slurry containing amorphous aluminum oxide to obtain amorphous aluminum oxide comprises the following steps: performing solid-liquid separation on the hydrolyzed slurry containing amorphous alumina to obtain a hydrolyzed solid phase material; The hydrolyzed solid phase material is washed and dried in sequence to obtain amorphous aluminum oxide.

9. The method according to claim 1, characterized in that The aluminum oxide content of the sodium aluminate solution is 50 g / L to 110 g / L; the sodium oxide content of the sodium aluminate solution is 60 g / L to 100 g / L.

10. The method according to claim 1, characterized in that The sodium oxide content of the amorphous aluminum oxide is less than or equal to 2.0%, and the impurity content of the amorphous aluminum oxide is less than or equal to 2.0%. The crystallinity of the pseudo-boehmite product is 76.5% to 81.1%.

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