Method for preparing rhenium dioxide by reducing perrhenate radical based on sodium formate

Abstract

The invention discloses a method for preparing rhenium dioxide based on sodium formate reduction of perrhenate radicals, and belongs to the technical field of metal material powder metallurgy preparation. The method comprises the following steps: adding perrhenate radicals into an aqueous solution containing sodium formate, taking ionizing radiation such as a < 60 > Co source and an electron accelerator as an energy source, and carrying out irradiation under the ionizing radiation to reduce precipitation to prepare rhenium dioxide. At present, perrhenate radicals can only be reduced to rhenium trioxide through a photoelectrocatalysis method, but the perrhenate radicals can be reduced to rhenium dioxide in a lower valence state through a radiation method; compared with a radiation method using alcohol as a sacrificial agent, the method has the advantages that rhenium dioxide precipitates instead of rhenium dioxide colloids can be directly generated by using sodium formate as the sacrificial agent, so that product separation is facilitated, and the yield is higher. More importantly, the usable radiation source is a commercial electron accelerator with an extensible scale, and the industrial prospect is achieved.

Description

Technical Field

[0001] This invention belongs to the field of powder metallurgy preparation technology of metallic materials, specifically relating to a method for preparing rhenium dioxide based on sodium formate reduction of perrhenate. Background Technology

[0002] Rhenium is a high-melting-point strategic metal. Due to its high heat resistance, high corrosion resistance, and high hardness, rhenium is widely needed in core components of high-temperature turbine engines and fusion reactors. Rhenium is found in molybdenum and copper ores and is produced as a byproduct of the metallurgical processing of these ores, in the form of perrhenate ions (ReO4). − Rhenium is dissolved in an aqueous solution in the form of ammonium perperurate and then separated and purified in subsequent processes. In conventional processes, rhenium needs to be precipitated as ammonium perperurate in the crystallization step, but the cations (such as potassium ions) of the precipitate salt used in this process can contaminate the final obtained metallic rhenium.

[0003] Over the past few decades, ionizing radiation technology has developed rapidly and is compatible with renewable energy and nuclear energy: gamma sources are a well-established product of neutron bombardment in nuclear reactors. 60 Co, and because electron beam accelerators are controllable and have high dose rates, they have broad prospects for industrialization. Summary of the Invention

[0004] In view of the current situation, this invention provides a method for preparing rhenium dioxide based on the reduction of perrhenate ions with sodium formate. Specifically, ionizing radiation is used to reduce and precipitate perrhenate ions to rhenium dioxide in aqueous solution with high yield, which can realize solid-liquid separation of rhenium and potassium. This method can effectively solve the problems of large recrystallization loss of ammonium perrhenate and difficulty in removing potassium ions in existing preparation methods. At the same time, this method has the advantages of simple operation, mild conditions, high rhenium reduction rate, high purity, and scalability.

[0005] To address the problems in the existing technology, the technical solution adopted by this invention is as follows: A method for preparing rhenium dioxide based on the reduction of perrhenate ions with sodium formate includes the following steps: S1. Add sodium formate and ammonium perrhenate to water to form an aqueous solution; S2. Argon gas is passed through the aqueous solution of S1 to remove oxygen, and then the solution is sealed and irradiated under ionizing radiation to form a black rhenium dioxide precipitate.

[0006] Preferably, the concentration of the sodium formate aqueous solution in S1 is 0.01-0.5 mol / L.

[0007] More preferably, the concentration of the sodium formate aqueous solution is 0.025-0.1 mol / L.

[0008] Preferably, S1 also includes adjusting the pH to 12.

[0009] Preferably, the reaction temperature of ionizing radiation in S2 is 25°C and the pressure is 0.1 MPa.

[0010] Preferably, the energy source of the ionizing radiation in S2 is... 60 Co source or electron beam accelerator.

[0011] A further preferred option is, 60 The absorption dose rate of the Co source is 10-800 Gy / min.

[0012] More preferably, the beam current range of the electron beam accelerator is 0.5-3 mA.

[0013] Beneficial effects:

[0014] Compared with the prior art, the method for preparing rhenium dioxide based on the reduction of perrhenate ions with sodium formate of the present invention has the following advantages: 1. The process conditions are mild, resulting in high product purity.

[0015] This invention can reduce perrhenate ions and precipitate them as rhenium dioxide using water as the reaction medium at room temperature and pressure, achieving effective solid-liquid separation of rhenium and potassium ions, avoiding the problem of cation contamination in traditional crystallization processes, and thus significantly improving product purity.

[0016] 2. The energy sources are mature and have industrialization potential.

[0017] The ionizing radiation energy source used in this invention is widely used in industry. 60 Co sources or electron beam accelerators have advantages such as controllability, continuity, and high dose rate. They can quickly complete the reduction reaction without high temperature and high pressure, significantly improving the reduction precipitation efficiency and facilitating large-scale production.

[0018] 3. The system has strong reducing properties, and the product can be directly precipitated.

[0019] This invention utilizes sodium formate to remove oxidizing hydroxyl radicals generated in radioactive water. • The perrhenate group (OH) forms a strong reducing system dominated by hydrated electrons and carbon dioxide radical anions, enabling complete reduction of perrhenate to rhenium dioxide solid precipitate. Compared to radiation systems using alcohols as sacrificial agents, this method avoids the formation of colloidal products, yields higher output, and simplifies separation. Detailed Implementation

[0020] The technical solution of the present invention will be further described in detail below with reference to the tables in the embodiments of the present invention, but the present invention is not limited to the following embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0021] Example 1

[0022] Sodium formate and ammonium perrhenate were added to water to prepare a mixed aqueous solution containing 50 mmol / L sodium formate and 2000 ppm perrhenate. Argon gas was passed into the mixed aqueous solution for 10 min to remove oxygen and obtain sample 1; Carbon dioxide was passed into the mixed aqueous solution for 10 min until saturation was achieved to obtain sample 2; Sample 3 was prepared by passing nitrous oxide into a mixed aqueous solution for 10 minutes until saturation.

[0023] After sealing the above three samples, place them in a suitable location. 60 Irradiation was performed for 75 hours using a Co source at an absorbed dose rate of 40 Gy / min. The concentration of residual rhenium in the water was then detected by ICP-OES (with a detection sensitivity line of 221.462 nm). The results are shown in Table 1.

[0024] Table 1. Effects of different processing gases on rhenium dioxide preparation

[0025] The results in the table show that when carbon dioxide is introduced, hydrated electrons are converted into carbon dioxide radical anions. When nitrous oxide is introduced, hydrated electrons are first converted into hydroxyl radicals, which are then converted into carbon dioxide radical anions by sodium formate. Therefore, both systems rely solely on carbon dioxide radical anions as the reducing species. However, when argon is introduced, both hydrated electrons and carbon dioxide radical anions are present. Since the reducing power of hydrated electrons is higher than that of carbon dioxide radical anions, the system with argon has a stronger reducing power than the previous two systems, which rely solely on carbon dioxide radical anions. In other words, rhenium exhibits the highest reduction rate when argon is introduced.

[0026] Example 2 Ammonium perrhenate was added to aqueous solutions containing sodium formate at different concentrations (10 mmol / L, 25 mmol / L, 50 mmol / L, 75 mmol / L, 100 mmol / L, 250 mmol / L, 500 mmol / L) to obtain samples 1-5 containing 2000 ppm perrhenate and sodium formate at different concentrations.

[0027] After purging with argon gas to remove oxygen and sealing, all five samples were placed in...60 Irradiation was performed for 15 hours under a Co source at an absorbed dose rate of 50 Gy / min. The concentration of residual rhenium in the water was then detected by ICP-OES after irradiation, and the results are shown in Table 2.

[0028] Table 2 Effect of different concentrations of sodium formate on the preparation of rhenium dioxide

[0029] The test results showed that the reduction rate of rhenium increased with increasing sodium formate concentration. However, when the sodium formate concentration exceeded 100 mmol / L, the increase in rhenium reduction rate remained essentially unchanged. This is because sodium formate plays a role in scavenging hydroxyl radicals and converting them into carbon dioxide radical anions. A sodium formate concentration of 100 mmol / L is sufficient to scaveng and convert most hydroxyl radicals, and further increasing the sodium formate concentration has little effect on the scavenging and conversion ability.

[0030] Example 3 In aqueous solutions containing 50 mmol / L sodium formate and 2000 ppm perrhenate, the pH values ​​were adjusted to 1, 3, 5, 7, 10, 11, 12, and 14 respectively using concentrated HCl (36% by mass) and NaOH. After purging with argon gas to remove oxygen and sealing, the solutions with different pH values ​​were placed in... 60 Irradiation was performed for 75 hours under a Co source at an absorbed dose rate of 40 Gy / min. The concentration of residual rhenium in the water was then detected by ICP-OES after irradiation. The results are shown in Table 3.

[0031] Table 3 Effect of different pH solutions on rhenium dioxide preparation

[0032] As can be seen from the table, the reduction rate of rhenium increases with the increase of pH value. Therefore, when preparing the solution, the pH can be adjusted to alkaline with sodium hydroxide solution, not exceeding 12.

[0033] Based on Examples 1-3, the optimal parameter combination for the process of this invention is as follows: In an aqueous solution containing 100 mmol / L sodium formate and 2000 ppm perrhenate, the pH of the solution is adjusted to 12 using NaOH. After deoxygenation by argon gas and sealing, subsequent irradiation under ionizing radiation is performed.

[0034] Example 4 An aqueous solution containing 100 mmol / L sodium formate and 350 ppm rhenium was prepared, deoxygenated by argon gas, sealed, and then irradiated for 5 min under a 2 MeV electron beam accelerator with a beam current intensity of 2 mA. The concentrations of rhenium and potassium ions in the water were detected by ICP-OES before and after irradiation.

[0035] Table 4. Concentrations of potassium and rhenium after electron beam accelerator treatment

[0036] The test results showed that the concentration of potassium ions remained basically unchanged in the aqueous solution before and after irradiation, while 98% of rhenium had precipitated from the solution, thus achieving rhenium-potassium separation.

[0037] Comparative Example Prepare a mixed aqueous solution containing 50 mmol / L methanol and 2000 ppm perrhenate by adding methanol and ammonium perrhenate to water; after deoxygenation by argon gas and sealing, place the solution in a container... 60 Irradiation with a Co source for 75 hours at an absorbed dose rate of 40 Gy / min resulted in the formation of a black rhenium dioxide colloid, which could not be separated from the solution. Only after adding sodium sulfate to a final concentration of 1 mol / L did the rhenium dioxide colloid gradually precipitate. At this point, the concentration of residual rhenium in the water was measured by ICP-OES, revealing a rhenium concentration of 98 ppm in the irradiated aqueous solution, representing a rhenium reduction rate of 72%.

[0038] The present invention and its embodiments have been described above illustratively, and this description is not restrictive. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A method for preparing rhenium dioxide based on the reduction of perrhenate with sodium formate, characterized in that, The method comprises the following steps: S1, adding sodium formate and ammonium perrhenate into water to form an aqueous solution; S2, sealing the aqueous solution of S1 after removing oxygen by argon and irradiating under ionizing radiation to form a black rhenium dioxide precipitate.

2. The method for preparing rhenium dioxide based on sodium formate reducing perrhenate according to claim 1, characterized in that, The concentration of the aqueous solution of sodium formate is 0.01-0.5 mol / L.

3. The method of claim 2, wherein the method is characterized by, The concentration of the aqueous solution of sodium formate is 0.025-0.1 mol / L.

4. The method for preparing rhenium dioxide by reducing perrhenate based on sodium formate according to claim 1, characterized in that, S1 further comprises adjusting pH to 12.

5. The method of claim 1, wherein the method is characterized by, The reaction temperature of ionizing radiation in S2 is 25℃, and the pressure is 0.1 MPa.

6. The method of claim 1, wherein the method is characterized by, The energy source of ionizing radiation in S2 is 60 Co source or electron beam accelerator.

7. The method of claim 6, wherein the method is characterized by, 60 The absorbed dose rate for the Co source is 10 - 800 Gy / min.

8. The method of claim 6, wherein the method is characterized by, The beam current range of the electron beam accelerator is 0.5-3 mA.

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