A molecular sieve adsorbent for extracting hafnium and a preparation method and application thereof

Abstract

The application provides a molecular sieve adsorbent for extracting hafnium and a preparation method and application thereof, and the preparation method comprises the following steps: (1) performing activation treatment on a raw material containing kaolin to obtain an activation product; and (2) mixing the activation product, a first alkali and a solvent, and performing a crystallization reaction to obtain the molecular sieve adsorbent. The activation process and the crystallization process are adopted to prepare a high-purity molecular sieve adsorbent with excellent adsorption performance. The method is simple in process, low in cost, green and environmentally friendly, and can realize efficient extraction of hafnium elements in a hafnium-containing solution, and a hafnium element recovery rate of more than 90% can be obtained, thereby effectively solving the problem that a chemical extractant is required for extracting hafnium elements in an aqueous solution.

Description

Technical Field

[0001] This invention belongs to the field of adsorption separation, specifically relating to a molecular sieve adsorbent for extracting hafnium, its preparation method, and its application. Background Technology

[0002] Zirconium exists primarily in the Earth's crust as zircon and zircon, while hafnium does not exist as a standalone mineral but is often found in association with zircon. The hafnium content in the most common zircon is typically 2-3 wt%. Due to its high melting point and resistance to high-temperature corrosion, hafnium is considered one of the most widely used metals in refractory materials. Zirconium has a small thermal neutron absorption cross section, only (0.18±0.02)×b (1b=10^2 ... -28 m 2 Hafnium (atoms) is often used as cladding and structural material for nuclear reactors; in contrast, hafnium has a large thermal neutron absorption cross section (115 × 10⁻⁶). -28 m 2 Zirconium (atom) is an important material for controlling thermonuclear reactions. As a material used to control nuclear reactions, its hafnium content must be less than 0.01%.

[0003] However, hafnium and zirconium have very similar chemical properties, making it difficult to extract hafnium separately. To address this, JV Kerrigan in France invented a tributyl phosphate (TBP)-HNO3 extraction system for separating zirconium and hafnium. However, in the TBP process, the zirconium partition ratio is higher than that of hafnium; to achieve hafnium separation and purification, over 98% of the zirconium is extracted into the organic phase, resulting in high extraction mass transfer. In the HSCN-MIBK system, the hafnium partition ratio is higher than that of zirconium, significantly reducing the amount of extractant used compared to the TBP process. However, this process suffers from problems such as the high water solubility of MIBK and the high toxicity of HSCN, greatly limiting its widespread adoption. Although subsequent researchers have improved the MIBK extraction system using solvents or extractants such as DIBK and P507, the problems with this process have not yet been effectively solved.

[0004] Currently, existing patents and industrial processes all employ traditional wet methods for separating zircon and hafnium, such as solvent extraction, which involves enriching the element during zircon smelting. This process suffers from drawbacks including a long hafnium extraction flow, complex extraction procedures, large quantities of required chemical reagents, high energy consumption, significant environmental pollution, poor separation efficiency, and low recovery rates. Furthermore, most existing literature and patent reports on zircon-hafnium separation focus on the separation coefficient of zircon-hafnium extraction, as well as considerations of new processes, costs, and environmental benefits. There are relatively few reports on the technical treatment of hafnium in the zircon-hafnium leaching residue and the hafnium-containing waste liquid lost during extraction.

[0005] Therefore, developing a low-energy, environmentally friendly, and efficient hafnium extraction technology is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a molecular sieve adsorbent for hafnium extraction, its preparation method, and its applications. This invention employs activation and crystallization processes to prepare a high-purity molecular sieve adsorbent with excellent adsorption performance. This method is not only simple, low-cost, and environmentally friendly, but also enables highly efficient extraction of hafnium from hafnium-containing solutions, achieving a recovery rate of over 90%. This effectively solves the problem of requiring chemical extractants for hafnium extraction from aqueous solutions.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a molecular sieve adsorbent, the method comprising the following steps:

[0009] (1) The raw material containing kaolin is activated to obtain the activated product;

[0010] (2) The activated product, the first base and the solvent are mixed and crystallized to obtain the molecular sieve adsorbent.

[0011] This invention employs activation and crystallization processes to prepare a high-purity molecular sieve adsorbent with excellent adsorption performance. This method is not only simple, low-cost, and environmentally friendly, but also enables efficient extraction of hafnium from hafnium-containing solutions, achieving a recovery rate of over 90% for hafnium. This effectively solves the problem of the current requirement for chemical extractants to extract hafnium from aqueous solutions.

[0012] The present invention does not specifically limit the raw materials containing kaolin. For example, they may be kaolin, rare earth slag, coal gangue or fly ash, etc.

[0013] As a preferred technical solution of the present invention, before the kaolin-containing raw material in step (1) is activated, the kaolin-containing raw material is crushed.

[0014] Preferably, after the crushing process, the raw material containing kaolin has a mesh size of 100-400 mesh, such as 100 mesh, 120 mesh, 140 mesh, 160 mesh, 180 mesh, 200 mesh, 220 mesh, 240 mesh, 260 mesh, 280 mesh, 300 mesh, 320 mesh, 340 mesh, 380 mesh, or 400 mesh.

[0015] Preferably, the activation treatment in step (1) includes thermal activation and / or alkali fusion.

[0016] Preferably, the specific steps of the thermal activation include: calcining the raw material containing kaolin.

[0017] In this invention, the raw materials containing kaolin are treated by thermal activation, which can effectively destroy the stable mineral phases in the raw materials and improve their reactivity.

[0018] The present invention does not specifically limit the container used for calcination, as long as it can withstand high temperatures.

[0019] Preferably, the specific steps of the alkali fusion include: mixing the raw material containing kaolin and the second alkali, and then performing a sintering treatment.

[0020] In this invention, the raw materials containing kaolin are treated by alkali fusion, which can effectively improve the solubility of the material and thus improve the conversion rate.

[0021] This invention does not specifically limit the container used for alkali melting, as long as it is alkali-resistant.

[0022] As a preferred technical solution of the present invention, the calcination temperature is 600-1700℃, for example, it can be 600℃, 800℃, 1000℃, 1200℃, 1400℃, 1600℃ or 1700℃, etc., preferably 900-1500℃.

[0023] In this invention, if the calcination temperature is too low, the effective components in the raw materials cannot be activated; if the calcination temperature is too high, caking is likely to occur, which will reduce the activity and cause energy waste.

[0024] Preferably, the calcination time is 0.5-24h, for example, it can be 0.5h, 1h, 3h, 5h, 7h, 10h, 15h, 20h or 24h, and more preferably 2-6h.

[0025] As a preferred embodiment of the present invention, the second alkali comprises any one or a combination of at least two of sodium hydroxide, potassium hydroxide, organic amine, or ammonia water.

[0026] Preferably, the mass ratio of the kaolin-containing raw material to the second alkali is 1:(0.1-5), for example, it can be 1:0.1, 1:0.2, 1:0.5, 1:1, 1:2, 1:3, 1:4 or 1:5, etc., preferably 1:(0.5-2).

[0027] In this invention, if the mass ratio of the raw material containing kaolin to the second alkali is too low, that is, if the amount of alkali used is too high, soluble aluminosilicates will be formed, which will prevent the synthesis of molecular sieves and result in a waste of alkali; if the mass ratio of the raw material containing kaolin to the second alkali is too high, that is, if the amount of alkali used is too low, the raw material cannot be fully activated and the reaction activity will be insufficient.

[0028] Preferably, the mixing time of the kaolin-containing raw material and the second alkali is 2-600 min, for example, it can be 2 min, 5 min, 10 min, 30 min, 50 min, 70 min, 90 min, 120 min, 150 min, 200 min, 300 min, 400 min, 500 min or 600 min, etc., preferably 60-120 min.

[0029] As a preferred technical solution of the present invention, the sintering temperature is 350-1200℃, for example, it can be 350℃, 400℃, 500℃, 600℃, 700℃, 800℃, 900℃, 1000℃, 1100℃ or 1200℃, etc., preferably 500-800℃.

[0030] Preferably, the sintering time is 0.5-24h, for example, it can be 0.5h, 1h, 3h, 5h, 7h, 10h, 15h, 20h or 24h, and is more preferably 1-6h.

[0031] As a preferred technical solution of the present invention, in step (2), the first alkali is an inorganic alkali, which includes any one or a combination of at least two of sodium hydroxide, potassium hydroxide or ammonia water.

[0032] Preferably, the solvent in step (2) is water.

[0033] Preferably, the mass ratio of the activation product, the first base, and the solvent in step (2) is 1:(0.1-10):(1-30), wherein the first base is selected in the range of "0.1-10", for example, 0.1, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, and the solvent is selected in the range of "1-30", for example, 1, 5, 10, 15, 20, 25, or 30.

[0034] In this invention, if the mass ratio of the activated product to the first alkali is too small, i.e., the amount of alkali used is too large, impurities with no adsorption capacity are easily generated; if the mass ratio of the activated product to the first alkali is too large, i.e., the amount of alkali used is too small, the molecular sieve structure product cannot be successfully converted.

[0035] Preferably, the mixing process in step (2) is accompanied by stirring.

[0036] Preferably, the mixing time in step (2) is 0.5-24h, for example, it can be 0.5h, 1h, 3h, 5h, 7h, 10h, 15h, 20h or 24h, and preferably 2-12h.

[0037] As a preferred technical solution of the present invention, the temperature of the crystallization reaction in step (2) is 50-260℃, for example, it can be 50℃, 70℃, 90℃, 100℃, 120℃, 140℃, 160℃, 180℃, 200℃, 220℃, 240℃ or 260℃, etc., preferably 60-180℃.

[0038] In this invention, if the temperature of the crystallization reaction is too low, it cannot be successfully converted into molecular sieve products; if the temperature of the crystallization reaction is too high, too many impurities will be generated, which will put high demands on the equipment and cause energy waste.

[0039] Preferably, the crystallization reaction time in step (2) is 2-72h, for example, it can be 1h, 5h, 10h, 15h, 20h, 25h, 30h, 35h, 40h, 45h, 50h, 55h, 60h, 65h, 70h or 72h, and preferably 12-36h.

[0040] Preferably, the temperature of the crystallization reaction in step (2) is a multi-stage temperature, which includes a primary temperature and a secondary temperature.

[0041] Preferably, the first-stage temperature is 50-100℃, for example, it can be 50℃, 60℃, 70℃, 80℃, 90℃ or 100℃, etc., and the time is 1-8h, for example, it can be 1h, 2h, 3h, 4h, 5h, 6h, 7h or 8h, etc.

[0042] Preferably, the secondary temperature is 100-240℃, for example, it can be 100℃, 120℃, 140℃, 160℃, 180℃, 200℃, 220℃ or 240℃, etc., and the time is 1-68h, for example, it can be 1h, 5h, 10h, 15h, 20h, 25h, 30h, 35h, 40h, 45h, 50h, 55h, 60h, 65h or 68h, etc.

[0043] Preferably, the heating rate from the first-level temperature to the second-level temperature is 1-10℃ / min, for example, it can be 1℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min or 10℃ / min, etc.

[0044] Preferably, after the crystallization reaction in step (2) is completed, the obtained product is post-processed, and the post-processing steps include washing and drying.

[0045] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0046] (I) Crush the raw material containing kaolin to 100-400 mesh, and then calcine it at 600-1700℃;

[0047] The calcination time is 0.5-24 hours.

[0048] (II) The calcined kaolin-containing raw material and the second alkali are mixed and ground for 2-600 min, and then sintered at 350-1200℃ to obtain the activated product;

[0049] The mass ratio of the raw material containing kaolin to the second alkali is 1:(0.1-5), and the sintering time is 0.5-24h.

[0050] (III) The activated product and the first alkali are mixed and stirred in water for 0.5-24h, and then subjected to hydrothermal crystallization reaction at 50-260℃. After the crystallization reaction is completed, the mixture is naturally cooled to room temperature to obtain the crystallized product.

[0051] The mass ratio of the activation product, alkali and water is 1:(0.1-10):(1-30), and the crystallization reaction time is 2-72h.

[0052] (IV) The crystallized product is washed 1-10 times and then dried at 30-300℃ for 1-48h to obtain the molecular sieve adsorbent.

[0053] In a second aspect, the present invention provides a molecular sieve adsorbent, which is prepared by the preparation method described in the first aspect.

[0054] Thirdly, the present invention provides an application of the molecular sieve adsorbent as described in the second aspect, wherein the molecular sieve adsorbent is used to extract hafnium from a hafnium-containing solution.

[0055] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] (1) The present invention uses an activation process and a crystallization process to prepare a high-purity molecular sieve adsorbent with excellent adsorption performance. This method is not only simple, low-cost and environmentally friendly, but also can achieve efficient extraction of hafnium from hafnium-containing solutions, with a recovery rate of over 90% for hafnium, effectively solving the problem that chemical extractants are required for extracting hafnium from aqueous solutions.

[0058] (2) The molecular sieve adsorbent provided by the present invention not only has excellent adsorption efficiency, but also can save the production cost of recovering hafnium. Attached Figure Description

[0059] Figure 1 The process flow diagrams for preparing molecular sieve adsorbents in Examples 1-3 of this invention are shown.

[0060] Figure 2 The XRD diffraction pattern is shown for the molecular sieve adsorbent prepared in Example 1 of this invention. Detailed Implementation

[0061] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0062] Example 1

[0063] This embodiment provides a method for preparing a molecular sieve adsorbent, the preparation method comprising the following steps:

[0064] (1) The coal gangue raw material is crushed to 200 mesh and then calcined at 1200℃ to complete the thermal activation;

[0065] The calcination time is 3 hours.

[0066] (2) The calcined coal gangue raw material and sodium hydroxide were mixed and ground for 5 minutes. Then the ground mixture was placed in a nickel crucible and sintered in a muffle furnace at 550°C to complete the alkali melting and obtain the activated product.

[0067] The mass ratio of coal gangue raw material to sodium hydroxide is 1:1.2, and the sintering time is 3 hours.

[0068] (3) The activated product, sodium hydroxide and potassium hydroxide were mixed and stirred in water for 3 hours. Then the uniformly stirred mixture was placed in a stainless steel high-pressure reactor lined with polytetrafluoroethylene and kept at 70°C for 3 hours. Then it was heated to 100°C and kept at 16 hours. The heating rate was 5°C / min. After the crystallization reaction was completed, it was naturally cooled to room temperature to obtain the crystallized product.

[0069] The mass ratio of the activated product, sodium hydroxide, potassium hydroxide, and water is 1:0.49:0.5:8.44.

[0070] (4) The crystallized product was centrifuged and washed 4 times, and then dried at 90°C for 12 hours to obtain the molecular sieve adsorbent.

[0071] Figure 2 The XRD diffraction pattern of the molecular sieve adsorbent prepared in this embodiment is shown. As can be seen from the figure, this pattern is in perfect agreement with the LSX card JSPDF:89-0070.

[0072] Example 2

[0073] This embodiment provides a method for preparing a molecular sieve adsorbent, the preparation method comprising the following steps:

[0074] (1) Crush the kaolin raw material to 150 mesh, then mix and grind it with potassium hydroxide for 2 minutes. Then place the ground mixture in a nickel crucible and sinter it in a muffle furnace at 500°C to complete the alkali fusion and obtain the activated product.

[0075] The mass ratio of kaolin raw material to potassium hydroxide is 1:0.5, and the sintering time is 6 hours.

[0076] (3) The activated product and sodium hydroxide were mixed and stirred in water for 12 hours. Then the uniformly stirred mixture was placed in a stainless steel high-pressure reactor lined with polytetrafluoroethylene and kept at 50°C for 8 hours. Then it was heated to 170°C and kept at 30 hours. The heating rate was 3°C / min. After the crystallization reaction was completed, it was naturally cooled to room temperature to obtain the crystallized product.

[0077] The mass ratio of the activated product, sodium hydroxide, and water is 1:5:15.

[0078] (4) The crystallized product was centrifuged and washed 6 times, and then dried at 150°C for 24 hours to obtain the molecular sieve adsorbent.

[0079] Example 3

[0080] This embodiment provides a method for preparing a molecular sieve adsorbent, the preparation method comprising the following steps:

[0081] (1) The rare earth slag raw material is crushed to 250 mesh and then calcined at 1500℃ to complete the thermal activation;

[0082] The calcination time is 2 hours.

[0083] (2) The calcined rare earth slag raw material and potassium hydroxide were mixed and stirred in water for 18 hours. Then the uniformly stirred mixture was placed in a stainless steel high-pressure reactor lined with polytetrafluoroethylene and kept at 100°C for 1 hour. Then it was heated to 240°C and kept at 240°C for 5 hours. The heating rate was 8°C / min. After the crystallization reaction was completed, it was naturally cooled to room temperature to obtain the crystallized product.

[0084] The mass ratio of the activated product, potassium hydroxide, and water is 1:3:20.

[0085] (4) The crystallized product was centrifuged and washed 5 times, and then dried at 200°C for 6 hours to obtain the molecular sieve adsorbent.

[0086] Figure 1The process flow diagrams for preparing molecular sieve adsorbents in Examples 1-3 are shown. As can be seen from the diagrams, Method 1 is the process flow diagram for preparing molecular sieve adsorbents in Example 1, Method 2 is the process flow diagram for preparing molecular sieve adsorbents in Example 2, and Method 3 is the process flow diagram for preparing molecular sieve adsorbents in Example 3.

[0087] Example 4

[0088] This embodiment provides a method for preparing a molecular sieve adsorbent, the preparation method comprising the following steps:

[0089] (1) Crush the fly ash raw material to 100 mesh, and then calcine it at 600℃ to complete the thermal activation;

[0090] The calcination time is 24 hours.

[0091] (2) The calcined fly ash raw material and potassium hydroxide were mixed and ground for 60 min. Then the ground mixture was placed in a nickel crucible and sintered in a muffle furnace at 800 °C to complete the alkali fusion and obtain the activated product.

[0092] The mass ratio of fly ash raw material to potassium hydroxide is 1:2, and the sintering time is 1 hour.

[0093] (3) The activated product and ammonia water are mixed and stirred in water for 1 hour. Then the uniformly stirred mixture is placed in a stainless steel high-pressure reactor lined with polytetrafluoroethylene and kept at 50°C for 72 hours. After the crystallization reaction is completed, it is naturally cooled to room temperature to obtain the crystallized product.

[0094] The mass ratio of the activated product, ammonia, and water is 1:10:1.

[0095] (4) The crystallized product is centrifuged and washed 10 times, and then dried at 30°C for 48 hours to obtain the molecular sieve adsorbent.

[0096] Example 5

[0097] This embodiment provides a method for preparing a molecular sieve adsorbent, the preparation method comprising the following steps:

[0098] (1) The coal gangue raw material is crushed to 400 mesh and then calcined at 1700℃ to complete the thermal activation;

[0099] The calcination time is 0.5 hours.

[0100] (2) The calcined coal gangue raw material and sodium hydroxide were mixed and ground for 120 min. Then the ground mixture was placed in a nickel crucible and sintered in a muffle furnace at 350 °C to complete the alkali melting and obtain the activated product.

[0101] The mass ratio of coal gangue raw material to sodium hydroxide is 1:5, and the sintering time is 24 hours.

[0102] (3) The activated product and potassium hydroxide were mixed and stirred in water for 24 hours. Then the uniformly stirred mixture was placed in a stainless steel high-pressure reactor lined with polytetrafluoroethylene and kept at 260°C for 2 hours. After the crystallization reaction was completed, it was naturally cooled to room temperature to obtain the crystallized product.

[0103] The mass ratio of the activated product, potassium hydroxide, and water is 1:0.1:30.

[0104] (4) The crystallized product is centrifuged and washed 4 times, and then dried at 300°C for 1 hour to obtain the molecular sieve adsorbent.

[0105] Example 6

[0106] The difference between this embodiment and embodiment 1 is that the calcination temperature in step (1) is 500°C.

[0107] The remaining preparation methods and parameters are consistent with those in Example 1.

[0108] Example 7

[0109] The difference between this embodiment and Embodiment 1 is that the calcination temperature in step (1) is 1800℃.

[0110] The remaining preparation methods and parameters are consistent with those in Example 1.

[0111] Example 8

[0112] The difference between this embodiment and Embodiment 1 is that the mass ratio of coal gangue raw material to sodium hydroxide is 1:0.05.

[0113] The remaining preparation methods and parameters are consistent with those in Example 1.

[0114] Example 9

[0115] The difference between this embodiment and Embodiment 1 is that the mass ratio of coal gangue raw material to sodium hydroxide is 1:6.

[0116] The remaining preparation methods and parameters are consistent with those in Example 1.

[0117] Example 10

[0118] The difference between this embodiment and Example 5 is that the mass ratio of the activated product to potassium hydroxide is 1:0.05.

[0119] The remaining preparation methods and parameters are consistent with those in Example 5.

[0120] Example 11

[0121] The difference between this embodiment and Example 5 is that the mass ratio of the activated product to potassium hydroxide is 1:15.

[0122] The remaining preparation methods and parameters are consistent with those in Example 5.

[0123] Example 12

[0124] The difference between this embodiment and Embodiment 5 is that the crystallization reaction temperature is 40°C.

[0125] The remaining preparation methods and parameters are consistent with those in Example 5.

[0126] Example 13

[0127] The difference between this embodiment and Embodiment 5 is that the crystallization reaction temperature is 280°C.

[0128] The remaining preparation methods and parameters are consistent with those in Example 5.

[0129] Comparative Example 1

[0130] The difference between this comparative example and Example 1 is that the coal gangue raw material is not activated, that is, steps (1) and (2) are not performed.

[0131] The remaining preparation methods and parameters are consistent with those in Example 1.

[0132] Performance testing

[0133] 1 g of each of the molecular sieve adsorbents prepared in Examples 1-13 and Comparative Example 1 was added to 20 mL of hafnium tetrachloride solution (where the hafnium concentration was 500 mg / L). The oscillation rate was set to 220 rpm, the reaction temperature was set to 40 °C, and the reaction time was 3 h. The extraction rate of hafnium element could be obtained by ICP-OES detection.

[0134] The test results are shown in Table 1.

[0135] Table 1

[0136]

[0137]

[0138] analyze:

[0139] As shown in the table above, this invention uses activation and crystallization processes to prepare a high-purity molecular sieve adsorbent with excellent adsorption performance. This method is not only simple, low-cost, and environmentally friendly, but also enables efficient extraction of hafnium from hafnium-containing solutions, achieving a recovery rate of over 90% for hafnium. This effectively solves the problem of the need for chemical extractants to extract hafnium from aqueous solutions.

[0140] A comparison of the data results from Examples 1 and 6-7 shows that if the calcination temperature is too low, the effective components in the raw materials cannot be activated, resulting in incomplete molecular sieve conversion; if the calcination temperature is too high, caking will occur, resulting in a reverse reduction in activity.

[0141] A comparison of the data results from Examples 1 and 8-9 shows that if the mass ratio of coal gangue raw material to sodium hydroxide is too small, soluble sodium aluminosilicate will be formed, which will prevent the synthesis of molecular sieves and prevent them from adsorbing hafnium. If the mass ratio of coal gangue raw material to sodium hydroxide is too large, the raw material will not be fully activated, resulting in a low conversion rate of molecular sieves.

[0142] A comparison of the data results from Examples 5 and 10-11 shows that if the mass ratio of the activation product to potassium hydroxide is too small, soluble potassium aluminosilicate will be formed, which will prevent the synthesis of molecular sieves and prevent them from adsorbing hafnium. If the mass ratio of the activation product to potassium hydroxide is too large, the raw materials will not be fully activated, resulting in a low conversion rate of molecular sieves.

[0143] A comparison of the data results from Examples 5 and 12-13 shows that if the temperature of the crystallization reaction is too low, it cannot be successfully converted into a molecular sieve; if the temperature of the crystallization reaction is too high, it is difficult to find a suitable reactor.

[0144] A comparison of the data results from Example 1 and Comparative Example 1 shows that if the raw materials containing kaolin are not activated beforehand, the raw materials will not have reactivity, thus making it impossible to synthesize molecular sieves.

[0145] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. An application of a molecular sieve adsorbent, characterized in that, The molecular sieve adsorbent is used to extract hafnium from hafnium-containing solutions; The method for preparing the molecular sieve adsorbent for hafnium extraction includes the following steps: (1) The raw material containing kaolin is activated to obtain the activated product; (2) The activated product, the first base and the solvent are mixed and crystallized to obtain the molecular sieve adsorbent; The activation treatment in step (1) includes thermal activation and alkali fusion; The specific steps of the thermal activation include: calcining the raw material containing kaolin. The specific steps of the alkali fusion include: mixing the thermally activated kaolin raw material with the second alkali and performing sintering treatment; The calcination temperature is 1200-1700℃; The mass ratio of the kaolin-containing raw material to the second alkali is 1:(0.5-2); In step (2), the mass ratio of the activated product, the first base, and the solvent is 1:(0.1-10):(1-30). The temperature of the crystallization reaction in step (2) is 50-260℃.

2. The application according to claim 1, characterized in that, Before the activation treatment of the raw material containing kaolin in step (1), the raw material containing kaolin is first crushed.

3. The application according to claim 2, characterized in that, After the crushing process, the raw material containing kaolin has a mesh size of 100-400 mesh.

4. The application according to claim 1, characterized in that, The calcination time is 0.5-24 hours.

5. The application according to claim 4, characterized in that, The calcination time is 2-6 hours.

6. The application according to claim 1, characterized in that, The second alkali includes any one or a combination of at least two of sodium hydroxide, potassium hydroxide, organic amines, or ammonia.

7. The application according to claim 1, characterized in that, The mixing time of the raw material containing kaolin and the second alkali is 2-600 min.

8. The application according to claim 7, characterized in that, The mixing time for the kaolin-containing raw material and the second alkali is 60-120 minutes.

9. The application according to claim 1, characterized in that, The sintering temperature is 350-1200℃.

10. The application according to claim 9, characterized in that, The sintering temperature is 500-800℃.

11. The application according to claim 1, characterized in that, The sintering time is 0.5-24 hours.

12. The application according to claim 11, characterized in that, The sintering time is 1-6 hours.

13. The application according to claim 1, characterized in that, Step (2) The first base is an inorganic base, which includes any one or a combination of at least two of sodium hydroxide, potassium hydroxide or ammonia water.

14. The application according to claim 1, characterized in that, The solvent used in step (2) is water.

15. The application according to claim 1, characterized in that, The mixing process described in step (2) involves stirring.

16. The application according to claim 1, characterized in that, The mixing time in step (2) is 0.5-24 hours.

17. The application according to claim 16, characterized in that, The mixing time in step (2) is 2-12 hours.

18. The application according to claim 1, characterized in that, The temperature of the crystallization reaction in step (2) is 60-180℃.

19. The application according to claim 1, characterized in that, The crystallization reaction in step (2) takes 2-72 hours.

20. The application according to claim 19, characterized in that, The crystallization reaction in step (2) takes 12-36 hours.

21. The application according to claim 1, characterized in that, The temperature of the crystallization reaction in step (2) is a multi-stage temperature, which includes a first-stage temperature and a second-stage temperature.

22. The application according to claim 21, characterized in that, The first-stage temperature is 50-100℃, and the time is 1-8 hours.

23. The application according to claim 21, characterized in that, The secondary temperature is 100-240℃, and the time is 1-68h.

24. The application according to claim 1, characterized in that, After the crystallization reaction in step (2) is completed, the obtained product is post-processed, and the post-processing steps include washing and drying.

25. The application according to claim 1, characterized in that, The method for preparing the molecular sieve adsorbent for hafnium extraction includes the following steps: (I) Crush the raw material containing kaolin to 100-400 mesh, and then calcine it at 1200-1700℃; The calcination time is 0.5-24 hours. (II) The calcined raw material containing kaolin and the second alkali are mixed and ground for 2-600 min, and then sintered at 350-1200℃ to obtain the activated product; The mass ratio of the raw material containing kaolin to the second alkali is 1:(0.5-2), and the sintering time is 0.5-24h. (III) The activated product and the first alkali are mixed and stirred in water for 0.5-24h, and then subjected to hydrothermal crystallization reaction at 50-260℃. After the crystallization reaction is completed, the mixture is naturally cooled to room temperature to obtain the crystallized product. The mass ratio of the activation product, alkali and water is 1:(0.1-10):(1-30), and the crystallization reaction time is 2-72h. (IV) The crystallized product is washed 1-10 times and then dried at 30-300℃ for 1-48h to obtain the molecular sieve adsorbent.

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