Method for preparing flaky gamma-aluminum oxide based on sintering process refined liquid
Through the steps of co-precipitation reaction, decomposition reaction, autoclave treatment and acetic acid replacement, the problem of high impurity content in the semen of the sintering method was solved, the preparation of high-purity flaky γ-alumina was achieved, and the production cost was reduced.
Patent Information
- Application Number
- CN202510887679.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-30
- Publication Date
- 2025-09-19
AI Technical Summary
It is difficult to effectively reduce the iron, sodium and calcium impurity contents in alumina products prepared from sintering semen with existing technologies, resulting in low product purity and high production costs.
A multi-stage collaborative process including co-precipitation reaction, decomposition reaction, autoclave treatment, roasting and acetic acid replacement is adopted. Through the combined use of aluminum hydroxide seeds, adsorbent, ammonium bicarbonate and hydrogen peroxide, silicates, iron oxides, calcium compounds and organic impurities in the sintering semen are removed to form flaky γ-alumina.
The preparation of high-purity flaky gamma-alumina with an iron content of less than 2.0 ppm, a sodium content of 10 ppm and less, and a calcium content of 3 ppm and less is achieved, thereby reducing production costs and improving product purity.
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Figure CN120664575A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of alumina preparation, and in particular to a method for preparing flaky γ-alumina based on sintering process. Background Art
[0002] High-purity γ-alumina can be widely used in fields such as catalyst supports and electronic materials due to its high specific surface area and pore volume. Currently, the preparation of γ-alumina relies on the traditional Bayer process, which requires aluminum hydroxide to be redissolved in alkaline solution, and then the mass concentration of aluminum hydroxide is adjusted to obtain a reaction raw material liquid. Seeds are then added to the reaction raw material liquid to pre-decompose the aluminum hydroxide to remove impurities and obtain an alumina product. However, the traditional Bayer process has cumbersome steps and high energy consumption, and the alumina product prepared often contains high levels of iron (>5ppm), sodium (>100ppm) and calcium (>10ppm), and the whiteness of the alumina product obtained is limited (generally 90 to 93). Although the sintering process semen (sodium aluminate solution) has a high content of impurities such as silicates, calcium and iron, it is rarely used in the production of high-purity alumina. However, if the sintering process semen is directly used, the production cost of alumina can be effectively reduced.
[0003] The premise of using sintered semen is to remove impurities from it. The current impurity removal mainly relies on activated carbon adsorption, hydrogen peroxide or ion exchange. These methods are difficult to achieve the impurity removal goals of iron content <2ppm, sodium content <10ppm, and calcium content <3ppm. Summary of the Invention
[0004] The present application provides a method for preparing flaky γ-alumina based on sodium aluminate semen by sintering method, in order to solve the following technical problem: how to reduce the impurity content of alumina products prepared by sintering semen.
[0005] In a first aspect, an embodiment of the present application provides a method for preparing flaky γ-alumina based on a sintering process semen, wherein the sintering process semen contains silicate, iron oxide, calcium compound, sodium oxide and organic matter, and the method comprises:
[0006] performing a co-precipitation reaction on sintered semen, aluminum hydroxide seeds and an adsorbent to remove silicates, iron oxides, calcium compounds and some organic matter from the sintered semen to obtain a mixed semen;
[0007] Decomposing the carbon dioxide and the mixed semen under a preset rotation speed to obtain an aluminum hydroxide product having a preset median particle size;
[0008] mixing the aluminum hydroxide product having a preset median particle size and a hydrophilic solvent to obtain an aluminum hydroxide slurry;
[0009] autoclave the aluminum hydroxide slurry and ammonium bicarbonate to allow the ammonium bicarbonate to neutralize sodium in the aluminum hydroxide crystal lattice in the aluminum hydroxide slurry, thereby obtaining an aluminum oxide raw material;
[0010] mixing hydrogen peroxide with the alumina raw material to oxidize the remaining organic matter in the alumina raw material to obtain alumina monohydrate;
[0011] calcining the alumina monohydrate to form sodium-containing impurities from the remaining sodium oxide in the alumina monohydrate, thereby obtaining a crude flaky γ-alumina product containing sodium impurities;
[0012] The crude flaky γ-alumina product is subjected to a substitution treatment using acetic acid to remove sodium-containing impurities in the crude flaky γ-alumina product, thereby obtaining flaky γ-alumina.
[0013] Optionally, the mass m1 of the aluminum hydroxide seed and the mass m2 of the sintering semen satisfy: m1:m2=(1.0 to 2.5):100; and / or
[0014] The mass m3 of the adsorbent and the mass m2 of the sintering semen satisfy: m3:m2=(0.1 to 0.5):100.
[0015] Optionally, the mass m4 of the ammonium bicarbonate and the mass m5 of the aluminum hydroxide slurry satisfy: m4:m5=(0.5 to 1.0):100; and / or
[0016] The mass m6 of the hydrogen peroxide and the mass m7 of the aluminum oxide raw material satisfy: m6:m7=(0.01 to 0.05):100.
[0017] Optionally, the coprecipitation reaction temperature is 50° C. to 76° C., and the coprecipitation reaction time is 60 min to 90 min; and / or
[0018] The initial temperature of the decomposition reaction is 25° C. to 60° C., and the time of the decomposition reaction is 2.0 h to 3.5 h; and / or
[0019] The pressure cooking temperature is 190° C. to 210° C., and the pressure cooking time is 2.0 h to 3.0 h.
[0020] Optionally, the calcination temperature is 590° C. to 610° C., and the calcination time is 1.5 h to 3.0 h; and / or
[0021] The replacement treatment time is 30 min to 60 min.
[0022] Optionally, the amount n1 of the acetic acid and the amount n2 of the sodium-containing impurities in the crude flaky γ-alumina product satisfy the following relationship: n1:n2=(1.25 to 1.35):1.
[0023] Optionally, the inlet flow rate of the carbon dioxide is 200 L / h to 800 L / h.
[0024] Optionally, the preset median particle size is 7 μm to 78 μm; and / or
[0025] The preset rotation speed is 150 r / min to 330 r / min.
[0026] Optionally, the solid content of the aluminum hydroxide slurry is 15% to 25%.
[0027] Optionally, the adsorbent includes activated carbon and / or diatomaceous earth.
[0028] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:
[0029] The present invention provides a method for preparing flaky gamma-alumina based on sintered semen. The method first involves co-precipitating impurities such as silicates, iron oxides, and calcium compounds in the sintered semen under the action of aluminum hydroxide seeds to form a precipitate. This precipitate may also carry along some organic matter, thereby separating these impurities from the sintered semen. Furthermore, an adsorbent is added to further adsorb the organic impurities in the sintered semen, thereby reducing the organic content of the sintered semen. Furthermore, the dispersing effect of carbon dioxide prevents aluminum hydroxide from agglomerating and carrying along impurities, thereby reducing the amount of impurities adsorbed by the aluminum hydroxide product. Furthermore, during the autoclaving process, ammonium bicarbonate reacts with the sodium in the aluminum hydroxide lattice in the aluminum hydroxide slurry to form soluble sodium bicarbonate, thereby removing the sodium. Furthermore, the oxidation effect of hydrogen peroxide decomposes the residual organic matter in the alumina monohydrate, thereby preventing the formation of residual impurities in the subsequent roasting stage. In addition, the ion exchange reaction of acetic acid based on sodium hydrogen can convert the sodium impurities in the crude flaky γ-alumina into soluble sodium acetate, thereby reducing the sodium impurity content of the crude flaky γ-alumina. In addition, the flaky γ-alumina can also provide more surface active sites, further enhancing the removal effect of sodium impurities.
[0030] Description of the drawings
[0031] 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.
[0032] 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.
[0033] Figure 1 A schematic flow chart of a method for preparing flaky γ-alumina by sintering semen provided in an embodiment of the present application. DETAILED DESCRIPTION
[0034] 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.
[0035] 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.
[0036] It should be noted that the process of preparing γ-alumina based on the sintering method involves roasting, and the morphology of the γ-alumina products prepared by roasting is mostly spherical or irregular crystal form, which makes it more difficult to control the particle size of γ-alumina.
[0037] This application addresses the difficult problem of particle size control of γ-alumina, combines it with the impurity removal requirements of sintering semen, and through a multi-stage collaborative process, can obtain flaky γ-alumina with an iron content below 2.0ppm, a sodium content of 10ppm and below, and a calcium content of 3pp and below.
[0038] Figure 1 The following is a schematic flow chart of a method for preparing flaky γ-alumina based on sintering semen provided in an embodiment of the present application;
[0039] like Figure 1 As shown, the embodiment of the present application provides a method for preparing flaky γ-alumina based on sintering semen, wherein the sintering semen contains silicate, iron oxide, calcium compound, sodium oxide and organic matter, and the method comprises:
[0040] S1. The sintered semen, aluminum hydroxide seeds and adsorbent were co-precipitated to remove silicates, iron oxides, calcium compounds and some organic matter from the sintered semen to obtain a mixed semen;
[0041] S2. The carbon dioxide and the semen mixture are decomposed under a preset speed to obtain an aluminum hydroxide product having a preset median particle size;
[0042] S3. The aluminum hydroxide product having a preset median particle size is mixed with a hydrophilic solvent to obtain an aluminum hydroxide slurry;
[0043] S4. The aluminum hydroxide slurry and ammonium bicarbonate are autoclaved to neutralize the sodium in the aluminum hydroxide lattice of the aluminum hydroxide slurry with the ammonium bicarbonate to obtain an alumina raw material;
[0044] S5. The hydrogen peroxide and the alumina raw material are mixed to oxidize the remaining organic matter in the alumina raw material to obtain alumina monohydrate;
[0045] S6. The alumina monohydrate is calcined to form sodium-containing impurities in the remaining sodium oxide of the alumina monohydrate to obtain a crude flaky γ-alumina product containing sodium impurities;
[0046] S7. Using acetic acid to perform a substitution treatment on the crude flaky γ-alumina product, so as to remove sodium-containing impurities in the crude flaky γ-alumina product and obtain flaky γ-alumina.
[0047] It should be noted that both the coprecipitation and decomposition reactions are carried out using stirring. Stirring ensures thorough mixing of the sintered semen, aluminum hydroxide seeds, and adsorbent, thereby improving the coprecipitation efficiency. Similarly, stirring facilitates the complete reaction of carbon dioxide with the mixed semen during the decomposition reaction, further enhancing the decomposition efficiency.
[0048] It should be noted that after the decomposition reaction is completed, the decomposition reaction product can be washed with high-purity deionized water (purity>99%) to remove soluble impurities.
[0049] It should be noted that after the autoclave is completed, the autoclave product can be cooled and filtered in sequence, and then the obtained filter cake can be washed with high-purity deionized water (purity>99%).
[0050] It should be noted that after the replacement treatment is completed, the replacement product can be subjected to solid-liquid separation to obtain a replacement solid phase, which is then washed with high-purity deionized water (purity > 99%) to obtain a pure flaky γ-alumina product.
[0051] It should be noted that the present invention provides a method for preparing flaky γ-alumina from sintered semen. This method achieves the preparation of low-impurity flaky γ-alumina through multi-stage synergistic action. The specific principle is as follows:
[0052] 1. Strengthening of impurity separation mechanism:
[0053] (1) Co-precipitation-adsorption synergistic impurity removal:
[0054] Aluminum hydroxide seeds induce sintering of semen to form co-precipitates of impurities such as silicates and iron oxides. At the same time, the activated carbon / diatomaceous earth adsorbent captures organic matter through physical adsorption and chemical bonding. This dual effect can effectively reduce the impurity content of mixed semen.
[0055] (2) CO2 dispersion and anti-agglomeration technology:
[0056] During the decomposition stage, micro-turbulence is generated at the gas-liquid interface through the continuous introduction of CO2 to prevent the aggregation of aluminum hydroxide particles and reduce the risk of impurities being agglomerated and wrapped.
[0057] 2. Lattice purification deep treatment:
[0058] (1) Pressure cooking and sodium removal reaction:
[0059] Ammonium bicarbonate can react with the sodium in the aluminum hydroxide lattice in the aluminum hydroxide slurry during the pressure cooking stage: NH4HCO3+Na + (lattice) → NaHCO3 + NH4 + , soluble NaHCO3 is generated, and these soluble salts can be removed by subsequent washing.
[0060] (2) Oxidation and removal of organic matter:
[0061] Hydrogen peroxide oxidizes the residual organic matter into CO2 and H2O, preventing the carbon impurities from being reduced to Fe3C and other difficult-to-remove impurities under high temperature conditions during roasting.
[0062] 3. Surface modification and final purification:
[0063] (1) Acetate ion exchange:
[0064] Acetic acid reacts with surface sodium to form CH3COOH+Na + →CH3COONa+H + The sodium acetate can be dissolved in the solution and separated from the flaky γ-alumina to reduce the sodium content of the alumina product.
[0065] (2) Advantages of lamellar structure
[0066] The crystal surface of flaky γ-alumina can display more Al-OH active sites, thereby improving the adsorption capacity of impurities and the efficiency of ion exchange.
[0067] Therefore, the embodiments of the present application provide a method for refining flaky gamma-alumina using a sintering process. This method effectively reduces the content of impurities such as silicates, iron oxides, calcium compounds, sodium oxide, and organic matter in the sintered concentrate through steps such as coprecipitation, fine filtration to remove impurities, carbon decomposition, ammonium bicarbonate autoclave, calcination, and acetic acid substitution.
[0068] In some optional embodiments, the mass m1 of the aluminum hydroxide seed and the mass m2 of the sintering semen satisfy: m1:m2=(1.0 to 2.5):100; and / or
[0069] The mass m3 of the adsorbent and the mass m2 of the sintering semen satisfy: m3:m2=(0.1 to 0.5):100.
[0070] In these embodiments, aluminum hydroxide seeds are mixed with sintered semen at a mass ratio of (1.0 to 2.5):100 to ensure sufficient aluminum hydroxide seeds in the sintered semen. These seeds can promote the co-precipitation of impurities such as silicates and iron oxides, thereby effectively reducing the impurity content in the sintered semen. In addition, adsorbent sufficiency can be achieved by adding adsorbents to the sintered semen at a mass ratio of 0.1 to 0.5:100. These adsorbents can effectively capture organic matter through physical adsorption and chemical bonding mechanisms, further reducing the impurity level of the sintered semen.
[0071] The mass m1 of the aluminum hydroxide seed can be 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 2.0 or 2.5.
[0072] The mass m3 of the adsorbent can be 0.1, 0.2, 0.3, 0.4 or 0.5.
[0073] In some optional embodiments, the mass m4 of the ammonium bicarbonate and the mass m5 of the aluminum hydroxide slurry satisfy: m4:m5=(0.5 to 1.0):100; and / or
[0074] The mass m6 of the hydrogen peroxide and the mass m7 of the aluminum oxide raw material satisfy: m6:m7=(0.01 to 0.05):100.
[0075] In these embodiments, in this study, a mixed system of ammonium bicarbonate and aluminum hydroxide slurry with a mass ratio of (0.5 to 1.0): 100 is used to ensure an adequate supply of ammonium bicarbonate in the aluminum hydroxide slurry. During the pressure cooking process, ammonium bicarbonate reacts fully with the sodium ions in the aluminum hydroxide crystal lattice to generate a large amount of soluble sodium bicarbonate salts. These salts are easily separated from the aluminum hydroxide crystals, thereby obtaining a high-purity alumina raw material. In addition, by adding hydrogen peroxide with a mass ratio of 0.01 to 0.05: 100 to the alumina raw material, an adequate supply of hydrogen peroxide is ensured, enabling it to undergo an effective redox reaction with the organic matter remaining in the raw material. This reaction promotes the oxidation of organic matter to form soluble impurities, which are then separated from the alumina raw material, significantly reducing the impurity content in the raw material.
[0076] The mass m4 of the ammonium bicarbonate can be 0.5, 0.6, 0.7, 0.8, 0.9 or 1.0.
[0077] The mass m6 of the hydrogen peroxide can be 0.01, 0.02, 0.03, 0.04 or 0.05.
[0078] It should be noted that the sodium impurity content of the ammonium bicarbonate is 7pm to 10ppm.
[0079] In some optional embodiments, the coprecipitation reaction temperature is 50° C. to 76° C., and the coprecipitation reaction time is 60 min to 90 min; and / or
[0080] The initial temperature of the decomposition reaction is 25° C. to 60° C., and the time of the decomposition reaction is 2.0 h to 3.5 h; and / or
[0081] The pressure cooking temperature is 190° C. to 210° C., and the pressure cooking time is 2.0 h to 3.0 h.
[0082] In these embodiments, the coprecipitation reaction, conducted at a temperature range of 50°C to 76°C and for a time interval of 60 to 90 minutes, can promote the coprecipitation of impurities such as silicates and iron oxides in the sintered semen induced by the aluminum hydroxide seed. Simultaneously, the activated carbon / diatomaceous earth adsorbent effectively captures organic matter through physical adsorption and chemical bonding, thereby effectively removing impurities from the sintered semen through a dual action. Furthermore, setting the initial temperature between 25°C and 60°C and continuing the decomposition reaction for 2.0 to 3.5 hours ensures that carbon dioxide induces the decomposition reaction of the mixed semen at an appropriate temperature and promotes uniform distribution of the reaction materials, thereby obtaining an aluminum hydroxide product with a predetermined median particle size and avoiding impurity entrapment due to product agglomeration. Furthermore, controlling the temperature between 190°C and 210°C and the autoclave time for 2.0 to 3.0 hours allows ammonium bicarbonate to fully react with the sodium hydroxide lattice in the aluminum hydroxide slurry to form soluble NaHCO3. These soluble salts can then be removed through a washing step, thereby increasing the purity of the alumina raw material.
[0083] The temperature of the coprecipitation reaction can be 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C or 76°C.
[0084] The coprecipitation reaction time can be 60 min, 65 min, 70 min, 75 min, 80 min, 85 min or 90 min.
[0085] The initial temperature of the decomposition reaction may be 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or 60°C.
[0086] The decomposition reaction time may be 2.0 h, 2.1 h, 2.2 h, 2.3 h, 2.4 h, 2.5 h, 3.0 h or 3.5 h.
[0087] The autoclave temperature may be 190°C, 195°C, 200°C, 205°C or 210°C.
[0088] The autoclave time may be 2.0 h, 2.1 h, 2.2 h, 2.3 h, 2.4 h, 2.5 h, 2.6 h, 2.7 h, 2.8 h, 2.9 h or 3.0 h.
[0089] It should be noted that the initial temperature of the decomposition reaction is brought about by carbon dioxide. Controlling the initial temperature of the decomposition reaction can promote the decomposition of the mixed semen to form aluminum hydroxide products with a preset median particle size.
[0090] In some optional embodiments, the calcination temperature is 590° C. to 610° C., and the calcination time is 1.5 h to 3.0 h; and / or
[0091] The replacement treatment time is 30 min to 60 min.
[0092] In these embodiments, under calcination conditions ranging from 590°C to 610°C and for 1.5 to 3.0 hours, alumina monohydrate undergoes a phase transformation to form flaky gamma-alumina. During this process, the sodium oxide impurities in the alumina monohydrate are converted into sodium-containing impurities, facilitating subsequent acetic acid replacement treatment. Furthermore, a replacement treatment time of 30 to 60 minutes is sufficient to ensure that the acetic acid fully replaces the sodium impurities in the crude gamma-alumina flakes, thereby improving the purity of the final gamma-alumina flakes.
[0093] The calcination temperature may be 590°C, 595°C, 600°C, 605°C or 610°C.
[0094] The calcination time may be 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h, 2.0 h, 2.5 h or 3.0 h.
[0095] The replacement treatment time can be 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min.
[0096] In some optional embodiments, the amount n1 of the acetic acid and the amount n2 of the sodium-containing impurities in the crude flaky γ-alumina satisfy the following relationship: n1:n2=(1.25 to 1.35):1.
[0097] In these embodiments, during the reaction of acetic acid and crude flaky gamma-alumina, maintaining the molar ratio of the two within the range of (1.25 to 1.35):1 ensures that the acetic acid fully reacts with the sodium impurity in the crude flaky gamma-alumina to produce soluble sodium acetate. This reaction product is easily separated from the flaky gamma-alumina, thereby obtaining a high-purity flaky gamma-alumina product.
[0098] The value of the amount of substance n1 of acetic acid can be 1.25, 1.26, 1.27, 1.28, 1.29, 1.30, 1.31, 1.32, 1.33, 1.34 or 1.35.
[0099] In some optional embodiments, the inlet flow rate of carbon dioxide is 200 L / h to 800 L / h.
[0100] In these embodiments, the introduction of carbon dioxide at a flow rate of 200 L / h to 800 L / h can induce a microturbulent effect, effectively preventing the aggregation of aluminum hydroxide particles, thereby reducing the risk of impurities being agglomerated and entrapped. Furthermore, carbon dioxide within this flow rate range can promote the carbon decomposition reaction of sodium aluminate in the mixed semen, thereby accelerating the decomposition of sodium aluminate to form aluminum hydroxide products.
[0101] The carbon dioxide introduction rate can be 200 L / h, 300 L / h, 400 L / h, 500 L / h, 600 L / h, 700 L / h or 800 L / h.
[0102] In some optional embodiments, the preset median particle size is 7 μm to 78 μm; and / or
[0103] The preset rotation speed is 150 r / min to 330 r / min.
[0104] In these embodiments, the preset median particle size range is set between 7 μm and 78 μm, ensuring a uniform particle size distribution of the aluminum hydroxide product. This facilitates the subsequent autoclaving stage, allowing ammonium bicarbonate to fully react with the sodium ions in the aluminum hydroxide lattice within the aluminum hydroxide slurry to produce soluble NaHCO₃. Furthermore, the preset rotational speed is between 150 r / min and 330 r / min, facilitating thorough mixing of the carbon dioxide with the semen mixture. Under the action of carbon dioxide, the sodium aluminate in the semen mixture is decomposed, forming a uniform aluminum hydroxide product. This effectively prevents aluminum hydroxide aggregation, reduces the possibility of impurities being trapped, and thereby reduces the impurity content of the aluminum hydroxide product.
[0105] The preset median particle size may be 7 μm, 8 μm, 9 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm or 78 μm.
[0106] The preset speed may be 150 r / min, 160 r / min, 170 r / min, 180 r / min, 190 r / min, 200 r / min, 250 r / min, 300 r / min, 310 r / min, 320 r / min or 330 r / min.
[0107] In some optional embodiments, the solid content of the aluminum hydroxide slurry is 15% to 25%.
[0108] In these embodiments, when the solid content of the aluminum hydroxide slurry is between 15% and 25%, uniform dispersion of the aluminum hydroxide crystals can be achieved, thereby promoting the reaction of ammonium bicarbonate with sodium in the aluminum hydroxide crystal lattice, thereby improving the purity of the alumina raw material.
[0109] In some optional embodiments, the adsorbent includes activated carbon and / or diatomaceous earth.
[0110] In these embodiments, activated carbon and / or diatomaceous earth are used as adsorbents. Due to the rich adsorption sites of these two materials, they can effectively adsorb impurities such as silicates and iron oxides formed during the co-precipitation reaction, forming a co-precipitated product. Furthermore, organic matter can be captured through physical adsorption and chemical bonding mechanisms, thereby improving the purity of the semen mixture.
[0111] 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.
[0112] Example 1
[0113] The composition of the sintering method semen includes: total alkali (NT): 100g / L, alumina (AO): 100g / L, and caustic ratio (AK): 1.48.
[0114] like Figure 1 As shown, a method for preparing flaky gamma-alumina based on sintering process semen, the sintering process semen contains silicate, iron oxide, calcium compound, sodium oxide and organic matter, including:
[0115] S1. The sintered semen, aluminum hydroxide seeds and adsorbent were co-precipitated to remove silicates, iron oxides, calcium compounds and some organic matter from the sintered semen to obtain a mixed semen;
[0116] S2. The carbon dioxide and the mixed semen are decomposed under a preset speed to obtain an aluminum hydroxide product having a preset median particle size;
[0117] S3. The aluminum hydroxide product having a preset median particle size and a hydrophilic solvent are mixed to obtain an aluminum hydroxide slurry;
[0118] S4. The aluminum hydroxide slurry and ammonium bicarbonate are pressure-cooked to neutralize the sodium in the aluminum hydroxide lattice of the aluminum hydroxide slurry with ammonium bicarbonate to obtain an alumina raw material;
[0119] S5. The hydrogen peroxide and the alumina raw material are mixed to oxidize the remaining organic matter in the alumina raw material to obtain alumina monohydrate;
[0120] S6. The alumina monohydrate is calcined to form sodium-containing impurities in the remaining sodium oxide of the alumina monohydrate to obtain a crude flaky γ-alumina product containing sodium impurities;
[0121] S7. Use deionized water to prepare the crude γ-alumina flaky product into a crude γ-alumina flaky product slurry with a solid content of 20%, and use acetic acid to replace the crude γ-alumina flaky product slurry to remove sodium impurities in the crude γ-alumina flaky product to obtain γ-alumina flaky product.
[0122] The mass m1 of the aluminum hydroxide seed and the mass m2 of the sintering semen satisfy: m1:m2=1.0:100;
[0123] The mass m3 of the adsorbent and the mass m2 of the sintering semen satisfy: m3:m2=0.2:100.
[0124] The mass m4 of ammonium bicarbonate and the mass m5 of aluminum hydroxide slurry satisfy: m4:m5=1.0:100; the mass m6 of hydrogen peroxide and the mass m7 of aluminum oxide raw material satisfy: m6:m7=0.01:100.
[0125] The coprecipitation reaction temperature was 72°C and the coprecipitation reaction time was 90 min;
[0126] The initial temperature of the decomposition reaction was 25°C, and the decomposition reaction time was 3.0 h;
[0127] The pressure cooking temperature is 200°C and the pressure cooking time is 2.5 hours.
[0128] The calcination temperature is 600°C and the calcination time is 1.5h;
[0129] The replacement treatment time is 30 min to 60 min.
[0130] The amount n1 of acetic acid and the amount n2 of sodium-containing impurities in the crude flaky γ-alumina satisfy the following relationship: n1:n2=1.30:1.
[0131] The flow rate of carbon dioxide is 200 L / h.
[0132] The preset median particle size is 7 μm;
[0133] The preset speed is 250r / min.
[0134] The solid content of the aluminum hydroxide slurry was 15%.
[0135] The adsorbent is activated carbon.
[0136] Example 2
[0137] Compared with Example 1, this embodiment has the following differences, and the rest are the same:
[0138] The mass m1 of the aluminum hydroxide seed and the mass m2 of the sintering semen satisfy: m1:m2=1.2:100;
[0139] The mass m3 of the adsorbent and the mass m2 of the sintering semen satisfy: m3:m2=0.2:100.
[0140] The mass m4 of ammonium bicarbonate and the mass m5 of aluminum hydroxide slurry satisfy: m4:m5=0.8:100; the mass m6 of hydrogen peroxide and the mass m7 of aluminum oxide raw material satisfy: m6:m7=0.01:100.
[0141] The coprecipitation reaction temperature was 72°C and the coprecipitation reaction time was 90 min;
[0142] The initial temperature of the decomposition reaction was 30°C, and the decomposition reaction time was 2.8 h;
[0143] The pressure cooking temperature is 200°C and the pressure cooking time is 2.5 hours.
[0144] The calcination temperature is 600°C and the calcination time is 1.6h;
[0145] The replacement treatment time is 35 minutes.
[0146] The amount n1 of acetic acid and the amount n2 of sodium-containing impurities in the crude flaky γ-alumina satisfy the following relationship: n1:n2=1.3:1.
[0147] The flow rate of carbon dioxide is 300 L / h.
[0148] The preset median particle size is 35 μm;
[0149] The preset speed is 250r / min.
[0150] The solid content of the aluminum hydroxide slurry was 18%.
[0151] The flaky γ-alumina crude product was prepared into a slurry of the flaky γ-alumina crude product with a solid content of 23% using deionized water.
[0152] Example 3
[0153] Compared with Example 1, this embodiment has the following differences, and the rest are the same:
[0154] The mass m1 of the aluminum hydroxide seed and the mass m2 of the sintering semen satisfy the following ratio: m1:m2=1.5:100;
[0155] The mass m3 of the adsorbent and the mass m2 of the sintering semen satisfy: m3:m2=0.2:100.
[0156] The mass m4 of ammonium bicarbonate and the mass m5 of aluminum hydroxide slurry satisfy: m4:m5=0.7:100; the mass m6 of hydrogen peroxide and the mass m7 of aluminum oxide raw material satisfy: m6:m7=0.02:100.
[0157] The coprecipitation reaction temperature was 72°C and the coprecipitation reaction time was 90 min;
[0158] The initial temperature of the decomposition reaction was 40°C, and the decomposition reaction time was 2.5 h;
[0159] The pressure cooking temperature is 200°C and the pressure cooking time is 2.5 hours.
[0160] The calcination temperature is 600°C and the calcination time is 1.8h;
[0161] The replacement treatment time is 40 minutes.
[0162] The amount n1 of acetic acid and the amount n2 of sodium-containing impurities in the crude flaky γ-alumina satisfy the following relationship: n1:n2=1.3:1.
[0163] The flow rate of carbon dioxide is 400 L / h.
[0164] The preset median particle size is 48 μm;
[0165] The preset speed is 220r / min.
[0166] The solid content of the aluminum hydroxide slurry is 20%.
[0167] The flaky γ-alumina crude product was prepared into a slurry of the flaky γ-alumina crude product with a solid content of 25% using deionized water.
[0168] Example 4
[0169] Compared with Example 1, this embodiment has the following differences, and the rest are the same:
[0170] The mass m1 of the aluminum hydroxide seed and the mass m2 of the sintering semen satisfy: m1:m2=1.8:100;
[0171] The mass m3 of the adsorbent and the mass m2 of the sintering semen satisfy: m3:m2=0.2:100.
[0172] The mass m4 of ammonium bicarbonate and the mass m5 of aluminum hydroxide slurry satisfy: m4:m5=0.6:100; the mass m6 of hydrogen peroxide and the mass m7 of aluminum oxide raw material satisfy: m6:m7=0.02:100.
[0173] The coprecipitation reaction temperature was 72°C and the coprecipitation reaction time was 90 min;
[0174] The initial temperature of the decomposition reaction was 50°C, and the decomposition reaction time was 2.3 h;
[0175] The pressure cooking temperature is 200°C and the pressure cooking time is 2.5 hours.
[0176] The calcination temperature is 600°C and the calcination time is 1.9h;
[0177] The replacement treatment time is 45 minutes.
[0178] The amount n1 of acetic acid and the amount n2 of sodium-containing impurities in the crude flaky γ-alumina satisfy the following relationship: n1:n2=1.3:1.
[0179] The flow rate of carbon dioxide is 500 L / h.
[0180] The preset median particle size is 60 μm;
[0181] The preset speed is 200r / min.
[0182] The solid content of the aluminum hydroxide slurry was 22%.
[0183] The flaky γ-alumina crude product was prepared into a slurry of the flaky γ-alumina crude product with a solid content of 27% using deionized water.
[0184] Example 5
[0185] Compared with Example 1, this embodiment has the following differences, and the rest are the same:
[0186] The mass m1 of the aluminum hydroxide seed and the mass m2 of the sintering semen satisfy: m1:m2=2.0:100;
[0187] The mass m3 of the adsorbent and the mass m2 of the sintering semen satisfy: m3:m2=0.2:100.
[0188] The mass m4 of ammonium bicarbonate and the mass m5 of aluminum hydroxide slurry satisfy: m4:m5=0.5:100; the mass m6 of hydrogen peroxide and the mass m7 of aluminum oxide raw material satisfy: m6:m7=0.03:100.
[0189] The coprecipitation reaction temperature was 72°C and the coprecipitation reaction time was 90 min;
[0190] The initial temperature of the decomposition reaction was 60°C, and the decomposition reaction time was 2.0 h;
[0191] The pressure cooking temperature is 200°C and the pressure cooking time is 2.5 hours.
[0192] The calcination temperature is 600°C and the calcination time is 2.0h;
[0193] The replacement treatment time is 50 min.
[0194] The amount n1 of acetic acid and the amount n2 of sodium-containing impurities in the crude flaky γ-alumina satisfy the following relationship: n1:n2=1.30:1.
[0195] The flow rate of carbon dioxide is 600 L / h.
[0196] The preset median particle size is 78 μm;
[0197] The preset speed is 170r / min.
[0198] The solid content of the aluminum hydroxide slurry is 25%.
[0199] The flaky γ-alumina crude product was prepared into a flaky γ-alumina crude product slurry with a solid content of 30% using deionized water.
[0200] Related experiments and effect data:
[0201] The aluminum oxide products obtained in each embodiment and comparative example were collected respectively, and their impurity contents were counted based on inductively coupled plasma mass spectrometry, and their morphological characteristics were counted under a scanning electron microscope. The specific results are shown in Table 1.
[0202] Table 1 Impurity content and morphology characteristics of alumina products of various embodiments and comparative examples
[0203]
[0204]
[0205] As can be seen from Table 1, the embodiment of the present application provides a method for preparing flaky γ-alumina based on sintering semen. This method uses multi-stage coordinated treatment such as aluminum hydroxide seed co-precipitation, carbon dioxide decomposition reaction, ammonium bicarbonate pressure cooking and acetic acid replacement treatment to obtain flaky γ-alumina with an iron content of less than 2.0 ppm, a sodium content of 10 ppm and less, and a calcium content of 3 pp and less, so as to effectively reduce the impurity content of the flaky γ-alumina.
[0206] Compared with Example 1, in Comparative Example 1, no ammonium bicarbonate was added for pressure cooking, and only the sodium in the lattice of a portion of the aluminum hydroxide crystals was precipitated by pressure, but the sodium impurities therein could not be effectively removed, resulting in the sodium impurity content of the final flaky γ-alumina being above 10 ppm.
[0207] Compared with Example 1, Comparative Example 2 uses more ammonium bicarbonate for autoclaving, which introduces more sodium impurities, so that the sodium impurity content of the final flaky γ-alumina is above 10 ppm.
[0208] Compared with Example 1, Comparative Example 3 uses a lower initial temperature for the decomposition reaction (the temperature of carbon dioxide is lower), while Comparative Example 4 uses a higher initial temperature for the decomposition reaction (the temperature of carbon dioxide is higher), which makes it difficult to control the median particle size of the final aluminum hydroxide within the preset median particle size range of 7 μm to 78 μm, thereby affecting the morphology of the final alumina product.
[0209] Compared with Example 1, in Comparative Example 5, ammonium bicarbonate was added but autoclaving was not performed, which made it difficult for sodium bicarbonate to react with sodium impurities in the lattice of aluminum hydroxide crystals to neutralize, making it difficult to effectively reduce the impurity content of the flaky γ-alumina.
[0210] Compared with Example 1, in Comparative Example 6, acetic acid was not used for replacement treatment, and it was difficult to replace the sodium impurities in the flaky γ-alumina, resulting in the sodium content of the final flaky γ-alumina being above 10 ppm.
[0211] In summary, the embodiment of the present application provides a method for preparing flaky γ-alumina based on sintering semen. This method uses multi-stage coordinated treatment such as aluminum hydroxide seed co-precipitation, carbon dioxide decomposition reaction, ammonium bicarbonate autoclave and acetic acid replacement treatment to ultimately obtain a flaky γ-alumina product with low sodium, low iron and low calcium.
[0212] In addition, the embodiment of the present application provides a method for preparing flaky γ-alumina based on sintering slurry. The sintering slurry used in this method does not require a re-dissolution and preparation step, which not only saves the preparation cost and energy consumption of high-purity alumina raw materials, but also can obtain a γ-alumina product with a unique flaky shape.
[0213] In addition, the present invention provides a method for preparing flaky γ-alumina based on sintering method, wherein the flaky γ-alumina prepared by the method has a thickness of 110 m 2 / g or more specific surface area, 0.30cm 3 / g and above pore volume and whiteness above 96.0. In addition, compared with traditional spherical alumina products, the flaky γ-alumina has excellent catalytic performance. At the same time, the median particle size of the flaky γ-alumina can be adjusted within the range of 7μm to 78μm to meet the diverse needs of different fields. These characteristics make the flaky γ-alumina suitable for use as a raw material in high-end fields such as high-purity catalyst carriers, electronic materials, and ruby ceramics.
[0214] In addition, the embodiment of the present application provides a method for preparing flaky γ-alumina based on sintering method. The flaky γ-alumina prepared by this method can not only meet the diverse needs of different usage scenarios, but also has high economy and market competitiveness.
[0215] 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 preparing flaky gamma-alumina based on sintered semen, wherein the sintered semen contains silicate, iron oxide, calcium compound, sodium oxide and organic matter, the method comprising: performing a co-precipitation reaction on sintered semen, aluminum hydroxide seeds and an adsorbent to remove silicates, iron oxides, calcium compounds and some organic matter from the sintered semen to obtain a mixed semen; Decomposing the carbon dioxide and the mixed semen under a preset rotation speed to obtain an aluminum hydroxide product having a preset median particle size; mixing the aluminum hydroxide product having a preset median particle size and a hydrophilic solvent to obtain an aluminum hydroxide slurry; autoclave the aluminum hydroxide slurry and ammonium bicarbonate to allow the ammonium bicarbonate to neutralize sodium in the aluminum hydroxide crystal lattice in the aluminum hydroxide slurry, thereby obtaining an aluminum oxide raw material; mixing hydrogen peroxide with the alumina raw material to oxidize the remaining organic matter in the alumina raw material to obtain alumina monohydrate; calcining the alumina monohydrate to form sodium-containing impurities from the remaining sodium oxide in the alumina monohydrate, thereby obtaining a crude flaky γ-alumina product containing sodium impurities; The crude flaky γ-alumina product is subjected to a substitution treatment using acetic acid to remove sodium-containing impurities in the crude flaky γ-alumina product, thereby obtaining flaky γ-alumina.
2. The method according to claim 1, characterized in that The mass m1 of the aluminum hydroxide seed and the mass m2 of the sintering solution satisfy the following conditions: m1:m2=(1.0 to 2.5):100; and / or The mass m3 of the adsorbent and the mass m2 of the sintering semen satisfy: m3:m2=(0.1 to 0.5):
100.
3. The method according to claim 1, characterized in that The mass m4 of the ammonium bicarbonate and the mass m5 of the aluminum hydroxide slurry satisfy: m4:m5=(0.5 to 1.0):100; and / or The mass m6 of the hydrogen peroxide and the mass m7 of the aluminum oxide raw material satisfy: m6:m7=(0.01 to 0.05):
100.
4. The method according to claim 1, wherein The coprecipitation reaction temperature is 50° C. to 76° C., and the coprecipitation reaction time is 60 min to 90 min; and / or The initial temperature of the decomposition reaction is 25° C. to 60° C., and the time of the decomposition reaction is 2.0 h to 3.5 h; and / or The pressure cooking temperature is 190° C. to 210° C., and the pressure cooking time is 2.0 h to 3.0 h.
5. The method according to claim 1, wherein The calcination temperature is 590° C. to 610° C., and the calcination time is 1.5 h to 3.0 h; and / or The replacement treatment time is 30 min to 60 min.
6. The method according to claim 1, characterized in that The amount n1 of the acetic acid and the amount n2 of the sodium-containing impurities in the crude flaky γ-alumina satisfy the following relationship: n1:n2=(1.25 to 1.35):
1.
7. The method according to claim 1, characterized in that The carbon dioxide is introduced at a flow rate of 200 L / h to 800 L / h.
8. The method according to claim 1, characterized in that The preset median particle size is 7 μm to 78 μm; and / or The preset rotation speed is 150 r / min to 330 r / min.
9. The method according to claim 1, characterized in that The solid content of the aluminum hydroxide slurry is 15% to 25%.
10. The method according to claim 1, characterized in that The adsorbent includes activated carbon and / or diatomaceous earth.