Submicron high-purity tungsten powder and method for preparing the same

Abstract

The application provides submicron high-purity tungsten powder and a preparation method thereof, and relates to the field of tungsten powder preparation. Ammonium paratungstate and ammonia water are mixed to obtain a mixture, the mixture is subjected to ammonia dissolution treatment and filtration to obtain a first ammonium tungstate solution; the first ammonium tungstate solution is subjected to first ion exchange by using a strong acid cation exchange resin to obtain a first ion-exchanged solution; the first ion-exchanged solution is subjected to second ion exchange by using a chelating resin to obtain a high-purity ammonium tungstate solution; the high-purity ammonium tungstate solution is subjected to vacuum spraying and freeze-drying to obtain a submicron tungsten precursor; and the submicron tungsten precursor is subjected to hydrogen reduction reaction to obtain submicron high-purity tungsten powder. The method can effectively remove insoluble particles and metal cation impurities in the solution, and obtain a high-purity tungsten precursor solution; and raw materials are easy to obtain, and the operation is simple.

Description

Technical Field

[0001] This application relates to the field of tungsten powder preparation, and in particular to a submicron-sized high-purity tungsten powder and its preparation method. Background Technology

[0002] Tungsten (W), a rare metal with excellent properties such as high melting point (3422℃), high hardness, good electrical conductivity and low vapor pressure, is widely used in many fields such as electronic information, metallurgical engineering, nuclear energy engineering, and aerospace.

[0003] Nuclear fusion devices require plasma-facing components to withstand harsh operating conditions such as high-temperature plasma, strong neutron irradiation, and high thermal loads. Tungsten, due to its high melting point, low sputtering rate, good thermal conductivity, and non-reaction with hydrogen, is considered the first candidate material for plasma applications. High-purity tungsten powder with low impurity content can effectively avoid plasma contamination. Tungsten or tungsten alloy materials prepared from submicron-sized tungsten powder have fine grains, high density, and good high-temperature stability, which can reduce radiation damage, improve radiation resistance, and extend service life. As the performance requirements for plasma-facing materials in nuclear fusion devices continue to increase, there is a need for tungsten powder with even higher purity and finer particle size to prepare high-performance tungsten and tungsten alloy materials.

[0004] To meet the requirements of high purity, high density, and radiation resistance of plasma-facing materials in nuclear fusion devices, it is urgent to improve the purity of tungsten powder and reduce its particle size. Summary of the Invention

[0005] The purpose of this application is to provide a submicron-sized high-purity tungsten powder and its preparation method to solve the above-mentioned problems.

[0006] To achieve the above objectives, the first aspect of this application provides a method for preparing submicron-sized high-purity tungsten powder, comprising:

[0007] Ammonium paratungstate and ammonia water are mixed to obtain a mixture, and the mixture is subjected to ammonia dissolution treatment and filtered to obtain a first ammonium paratungstate solution;

[0008] The first ammonium tungstate solution was subjected to a first ion exchange using a strong acid cation exchange resin to obtain a solution after the first ion exchange.

[0009] The solution after the first ion exchange was subjected to a second ion exchange using a chelating resin to obtain a high-purity ammonium tungstate solution.

[0010] The high-purity ammonium tungstate solution was subjected to vacuum spraying and freeze-drying to obtain a submicron-sized tungsten precursor.

[0011] The submicron-sized tungsten precursor was subjected to a hydrogen reduction reaction to obtain submicron-sized high-purity tungsten powder.

[0012] Optionally, the method for preparing submicron-sized high-purity tungsten powder satisfies at least one of the following conditions:

[0013] A. The purity of the ammonium paratungstate is ≥99.95%;

[0014] B. The mass concentration of the ammonia solution is 5%-25%;

[0015] C. The solid-liquid ratio of the ammonium paratungstate and the ammonia solution is 1g:5mL-10mL;

[0016] D. The temperature of the ammonia solvent treatment is 60℃-90℃, and the pressure is 5MPa-10MPa;

[0017] E. The filtration includes a first filtration and a second filtration performed sequentially;

[0018] The filter paper of the first filter has a pore size of 3μm-5μm;

[0019] The filter paper of the second filter has a pore size of 0.2μm-0.5μm.

[0020] Optionally, the method for preparing submicron-sized high-purity tungsten powder satisfies at least one of the following conditions:

[0021] A. The temperature for ion exchange is 20℃-60℃;

[0022] B. After the ion exchange is performed, the pH value of the high-purity ammonium tungstate solution is adjusted with ammonia.

[0023] C. The strongly acidic cation exchange resin includes a strongly acidic 001×7 cation exchange resin;

[0024] D. The chelating resin includes chelating Lewatit TP207 resin.

[0025] Optionally, the pH value is 7-9.

[0026] Optionally, the method for preparing submicron-sized high-purity tungsten powder satisfies at least one of the following conditions:

[0027] A. The concentration of the high-purity ammonium tungstate solution is 5 g / L-20 g / L;

[0028] B. The temperature of the high-purity ammonium tungstate solution is 20℃-30℃;

[0029] C. Na in the high-purity ammonium tungstate solution + Ion concentration is 0.1-10 ppm, K + The ion concentration is 0.1-10 ppm, Ca 2+ The ion concentration is 0.1-10 ppm, Mg2+ The ion concentration is 0.1-5 ppm, Fe 3+ and Fe 2+ The ion concentration is 0.1-10 ppm, Cu 2 + The ion concentration is 0.1-3 ppm, Ni 2+ The ion concentration is 0.1-5 ppm, Al 3+ The ion concentration is 0.1-5 ppm.

[0030] Optionally, the method for preparing submicron-sized high-purity tungsten powder satisfies at least one of the following conditions:

[0031] A. The feed flow rate of the vacuum spray is 5 mL / min-25 mL / min;

[0032] B. The nozzle orifice diameter of the vacuum spray is 0.5mm-1.5mm;

[0033] C. The freezing temperature for the freeze-drying process is -40℃ to -80℃, and the drying temperature is 40℃ to 50℃.

[0034] D. During the freeze-drying process, the vacuum degree is maintained at ≤100Pa, and the vacuum degree is maintained at ≤5Pa after the drying is completed.

[0035] Optionally, the hydrogen reduction reaction includes a first hydrogen reduction reaction and a second hydrogen reduction reaction carried out sequentially;

[0036] The temperature of the first hydrogen reduction reaction is 600℃-650℃, the boat pushing speed is 15min / boat-30min / boat, the boat loading amount is 100g / boat-300g / boat, and the hydrogen flow rate is 2.0m³. 3 / h-3.0m 3 / h;

[0037] The second hydrogen reduction reaction was carried out at a temperature of 850℃-950℃, with a boat pushing speed of 15min / boat-30min / boat, a boat loading capacity of 100g / boat-300g / boat, and a hydrogen flow rate of 2.5m³ / min. 3 / h-4.5m 3 / h.

[0038] Optionally, the method for preparing submicron-sized high-purity tungsten powder satisfies at least one of the following conditions:

[0039] A. After the freeze-drying process, the sample is then sieved.

[0040] B. After the hydrogen reduction reaction is carried out, a passivation treatment is also performed;

[0041] The passivation treatment includes: introducing N2 and / or Ar into the material after hydrogen reduction reaction.

[0042] The second aspect of this application provides a submicron-sized high-purity tungsten powder, which is prepared by the method described above.

[0043] Optionally, the submicron-sized high-purity tungsten powder satisfies at least one of the following conditions:

[0044] A. The purity of the submicron-grade high-purity tungsten powder is ≥99.995%;

[0045] B. The particle size of the submicron-sized high-purity tungsten powder is 0.1-1 μm.

[0046] Compared with the prior art, the beneficial effects of this application include:

[0047] The method for preparing submicron-sized high-purity tungsten powder provided in this application employs a series process of two specific ion exchange resins. Through staged selective adsorption, complementary pH adaptability, and kinetic synergy, it achieves efficient removal of various metal cation impurities in ammonium tungstate solution, obtaining a high-purity tungsten precursor solution. Furthermore, the raw materials are readily available, the operation is simple, and the equipment requirements are not high, reducing the difficulty of preparing submicron-sized tungsten powder and improving the practicality of the method.

[0048] The submicron-grade high-purity tungsten powder provided in this application has high purity and fine particle size, which meets the requirements of tungsten powder for plasma-oriented materials in nuclear fusion devices. Attached Figure Description

[0049] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0050] Figure 1 Here is a SEM image of the tungsten precursor powder prepared in Example 1;

[0051] Figure 2 The image shows a SEM image of the submicron-sized high-purity tungsten powder prepared in Example 1. Detailed Implementation

[0052] As used in this article:

[0053] "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0054] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0055] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0056] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0057] "Parts by mass" refers to the basic unit of measurement that expresses the mass ratio of multiple components. One part can represent any unit mass, such as 1g or 2.689g. If we say that component A has "a" parts by mass and component B has "b" parts by mass, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it can mean that the mass of component A is aK and the mass of component B is bK (K is any number representing a multiplier). It is important to understand that, unlike the number of parts by mass, the sum of the mass parts of all components is not limited to 100 parts.

[0058] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0059] The first aspect of this application provides a method for preparing submicron-sized high-purity tungsten powder, comprising:

[0060] Ammonium paratungstate and ammonia water are mixed to obtain a mixture, and the mixture is subjected to ammonia dissolution treatment and filtered to obtain a first ammonium paratungstate solution;

[0061] The first ammonium tungstate solution was subjected to a first ion exchange using a strong acid cation exchange resin to obtain a solution after the first ion exchange.

[0062] The solution after the first ion exchange was subjected to a second ion exchange using a chelating resin to obtain a high-purity ammonium tungstate solution.

[0063] The high-purity ammonium tungstate solution was subjected to vacuum spraying and freeze-drying to obtain a submicron-sized tungsten precursor.

[0064] It should be noted that the submicron-sized tungsten precursor was prepared by vacuum spraying and freeze drying. The high-purity ammonium tungstate solution rapidly condensed into fine ice crystals in a low-temperature environment under the high-speed rotation of the atomizing disk, and the water in the frozen material directly sublimated under vacuum conditions, finally obtaining dried submicron tungsten precursor particles. The prepared tungsten precursor particles have regular morphology, few hard agglomerates, and small and uniform particle size, which provides the necessary conditions for the preparation of ultrafine tungsten powder.

[0065] The submicron-sized tungsten precursor was subjected to a hydrogen reduction reaction to obtain submicron-sized high-purity tungsten powder.

[0066] It is important to note that precise control of the reduction temperature and holding time, along with increasing the hydrogen flow rate, is crucial to prevent excessive growth of the tungsten powder and to obtain tungsten powder with high purity and fine particle size.

[0067] In some embodiments, the method for preparing submicron-sized high-purity tungsten powder satisfies at least one of the following conditions:

[0068] A. The purity of the ammonium paratungstate is ≥99.95%;

[0069] Optionally, the purity of ammonium paratungstate can be any value of 99.95%, 99.99%, 99.999%, 99.9999%, or ≥99.95%.

[0070] B. The mass concentration of the ammonia solution is 5%-25%;

[0071] Optionally, the mass concentration of ammonia water can be any value between 5%, 10%, 15%, 20%, 25%, or 5%-25%.

[0072] It should be noted that ammonium paratungstate has a relatively complex structure and low solubility in water or ammonia solution at room temperature. Its solubility is greatly affected by ammonia concentration, temperature, and pressure. Increasing the ammonia concentration can increase the alkalinity (pH) of the solution, promoting the complexation reaction of ammonium paratungstate (such as the formation of [WO4]). 2- or [H] x Wy O z ] n- (such as soluble complexes), but excessively high ammonia concentrations can lead to increased ammonia volatilization and a deterioration of the operating environment. On the other hand, excessive alkalinity may cause APT to decompose into metatungstate or other unstable products. Therefore, an ammonia concentration in the range of 5%-25% can promote the complexation reaction of ammonium tungstate without easily causing APT decomposition.

[0073] C. The solid-liquid ratio of the ammonium paratungstate and the ammonia solution is 1g:5mL-10mL;

[0074] Optionally, the solid-liquid ratio of ammonium paratungstate and ammonia water can be any value between 1g:5mL, 1g:6mL, 1g:7mL, 1g:8mL, 1g:9mL, 1g:10mL or 1g:5mL-10mL;

[0075] D. The temperature of the ammonia solvent treatment is 60℃-90℃, and the pressure is 5MPa-10MPa;

[0076] Optionally, the temperature for ammonia leaching can be any value between 60℃, 70℃, 80℃, 90℃ or 60℃-90℃, and the pressure can be any value between 5MPa, 6MPa, 7MPa, 8MPa, 9MPa, 10MPa or 5MPa-10MPa.

[0077] It should be noted that increasing the temperature can improve the dissolution kinetics rate and promote solid-liquid mass transfer. If the temperature is too high, it needs to be controlled in conjunction with pressure. A high-pressure environment can suppress ammonia volatilization and indirectly increase the effective concentration of ammonia. At the same time, it can promote the shift of the dissolution equilibrium phase in the direction of dissolution. However, excessively high temperatures may cause APT to gradually decompose into tungsten oxide or ammonium metatungstate, increasing the risk of thermal decomposition of APT.

[0078] E. The filtration includes a first filtration and a second filtration performed sequentially;

[0079] The filter paper of the first filter has a pore size of 3μm-5μm;

[0080] Optionally, the pore size of the filter paper for the first filter can be any value between 3μm, 4μm, 5μm, or 3μm-5μm;

[0081] The filter paper of the second filter has a pore size of 0.2μm-0.5μm.

[0082] Optionally, the pore size of the filter paper for the second filter can be any value between 0.2μm, 0.3μm, 0.4μm, 0.5μm, or 0.2μm-0.5μm.

[0083] It is important to note that after ammonium paratungstate (APT) is completely dissolved, a two-stage filtration process is performed to remove impurities of different particle sizes, ensuring high solution purity and process stability. The first filtration primarily uses micron-sized filter paper to remove large suspended particles or incompletely dissolved coarse particles (such as raw material residues or impurities introduced by mechanical stirring). Submicron-sized filter paper cannot be used directly, as this can easily cause large particles to rapidly clog the filter membrane pores, reducing filtration efficiency and increasing costs. Therefore, the pore size of the first-stage filter paper is selected to be 3μm-5μm to remove insoluble visible precipitates. During APT dissolution, pH or temperature fluctuations can easily form colloidal tungstates. These colloidal particles may trigger heterogeneous nucleation in subsequent reactions, affecting solution stability. Therefore, submicron-sized filter paper is needed to trap these submicron-sized particles (such as colloidal particles or nanoscale precipitates) to ensure high solution purity. Thus, the second filtration primarily uses secondary filter paper with a pore size of 0.2μm-0.5μm to remove ultrafine impurity particles. In summary, the two-stage filtration system employs a "coarse-to-fine" grading strategy, balancing efficiency and precision to ensure the purity of the ammonium paratungstate solution meets the requirements of high-end applications. The primary filtration stage is an economical and efficient pretreatment, while the secondary filtration stage is the key step in achieving ultra-clean processes.

[0084] In some embodiments, the method for preparing submicron-sized high-purity tungsten powder satisfies at least one of the following conditions:

[0085] A. The temperature for ion exchange is 20℃-60℃;

[0086] Optionally, the ion exchange temperature can be any value between 20℃, 30℃, 40℃, 50℃, 60℃, or 20℃-60℃.

[0087] B. After the ion exchange is performed, the pH value of the high-purity ammonium tungstate solution is adjusted with ammonia.

[0088] In some embodiments, the pH value is 7-9;

[0089] Optionally, the pH value can be 7, 7.5, 8, 8.5, 9, or any value between 7 and 9;

[0090] It is important to note that after ion exchange, ammonia should be added to maintain the pH of the high-purity ammonium tungstate solution between 7 and 9. This helps prevent precipitation (APT is easily hydrolyzed under weakly acidic to neutral conditions to form insoluble metatungstate acid (H₂W)). 12 O4 2- Alternatively, tungstic acid (H2WO4) can be added; ammonia can be used to neutralize the H+ in the high-purity ammonium tungstate solution. + (Maintaining an alkaline environment to inhibit hydrolysis) and stabilizing ammonium tungstate complexes (within the pH range of 7-9, tungstate ions ([WO4])) 2- ) and NH4+ Forming stable soluble complexes (such as (NH4)). 10 H2W 12 O 42 To prevent spontaneous condensation and precipitation, when the pH is 7-9, impurity precipitation can be suppressed, ensuring that the product is pure ammonium molybdate.

[0091] Furthermore, the effect of pH value on subsequent spray freeze-drying is as follows: when the pH value is 7-9, the high-purity ammonium tungstate solution has moderate viscosity and low surface tension, which is conducive to the formation of uniform microdroplets through atomization; at the same time, the alkaline environment can inhibit hydrolysis reaction, avoid precipitation before drying, and ensure solution homogeneity; therefore, when the pH value is 7-9, the surface charge (Zeta potential) of the high-purity ammonium tungstate solution on the atomized droplets is more negative, reducing agglomeration and forming spherical particles.

[0092] It should also be noted that during the freeze-drying process, pH affects the hydrogen bond network of water. Alkaline solutions may form more ordered ice crystals, resulting in more uniform pores in the dried powder. If the pH deviates, it can lead to local precipitation, turbulent ice crystal structure, and powder clumping. At the same time, trace amounts of NH3 may escape during the sublimation stage, potentially forming a loose and porous structure and increasing the specific surface area of ​​the powder.

[0093] C. The strongly acidic cation exchange resin includes a strongly acidic 001×7 cation exchange resin;

[0094] D. The chelating resin includes chelating Lewatit TP207 resin.

[0095] It is important to note that strongly acidic 001×7 cation exchange resins preferentially adsorb high-valence cations, such as Fe, under acidic conditions. 3+ Al 3+ Ca 2+ Mg 2+ By initially removing most of the high-valence cations, the occupancy of these ions on the adsorption sites of the chelating resin is reduced, avoiding competitive adsorption, thus enabling the chelating resin to more efficiently adsorb residual low-concentration transition metals, such as Cu. 2+ Ni 2+ etc.; Strong acid 001×7 cation exchange resin for the removal of Ca 2+ Mg 2+ This reduces the risk of subsequent tungstate precipitation (such as CaWO4) and prevents impurities from being trapped in the precipitate, which could lead to resin failure. Furthermore, the chelating Lewatit TP207 resin reacts with Cu under neutral to weakly alkaline conditions. 2+ Ni 2+The transition metals form stable chelates, which have the best performance at pH 4-6. This complements the acidic environment of the strongly acidic 001×7 cation exchange resin at pH 2-4, avoiding the pH limitation of a single resin. At the same time, after adjusting the pH to neutral, the chelating groups of the TP207 resin are fully dissociated, which improves the adsorption kinetics of transition metals.

[0096] The high exchange rate and mechanical strength of 001×7 resin enable rapid processing of high-concentration impurities and shorten the overall process time; the uniform particle size distribution of Lewatit TP207 resin reduces flow line resistance, increases linear flow velocity, avoids blockage and accelerates mass transfer, and high-speed impurity removal can be achieved through a two-stage resin series process.

[0097] In some embodiments, the method for preparing submicron-sized high-purity tungsten powder satisfies at least one of the following conditions:

[0098] A. The concentration of the high-purity ammonium tungstate solution is 5 g / L-20 g / L;

[0099] Optionally, the concentration of the high-purity ammonium tungstate solution can be 5 g / L, 10 g / L, 15 g / L, 20 g / L or any value between 5 g / L and 20 g / L;

[0100] It is important to note that when the concentration of the high-purity ammonium tungstate solution is between 5 g / L and 20 g / L, this range is considered a low-concentration solution with moderate viscosity, facilitating atomization into uniform droplets. This avoids the problem of excessive viscosity and atomization difficulties associated with high concentrations. Furthermore, low-concentration solutions result in uniform moisture distribution in the freezing chamber, controllable ice crystal size, and a uniform pore structure in the dried powder. If the concentration is too low (<5 g / L), the yield decreases significantly, the powder becomes too fine, easily scattering and being lost, reducing the throughput per unit volume and increasing energy consumption. If the concentration is too high (>20 g / L), the atomized droplets are uneven, the internal ice crystals are large during freezing, and the particles clump together after drying, reducing the specific surface area.

[0101] B. The temperature of the high-purity ammonium tungstate solution is 20℃-30℃;

[0102] Optionally, the temperature of the high-purity ammonium tungstate solution can be any value between 20℃, 25℃, 30℃, or 20℃-30℃.

[0103] It is important to note that when the temperature of the high-purity ammonium tungstate solution is between 20℃ and 30℃, the ammonia volatilization rate is relatively low within this temperature range. This avoids excessive NH3 escape due to high temperature, which could disrupt the ammonium salt balance in the solution. If the temperature is too low, the solution viscosity increases, the atomized droplet size becomes larger, and the powder particle size distribution becomes wider after freeze-drying. If the temperature is too high, NH3 volatilization intensifies, the solution pH decreases (potentially <7), and APT hydrolysis and precipitation occurs.

[0104] C. Na in the high-purity ammonium tungstate solution+ Ion concentration is 0.1-10 ppm, K + The ion concentration is 0.1-10 ppm, Ca 2+ The ion concentration is 0.1-10 ppm, Mg 2+ The ion concentration is 0.1-5 ppm, Fe 3+ and Fe 2+ The ion concentration is 0.1-10 ppm, Cu 2 + The ion concentration is 0.1-3 ppm, Ni 2+ The ion concentration is 0.1-5 ppm, Al 3+ The ion concentration is 0.1-5 ppm.

[0105] Optionally, the Na in the high-purity ammonium tungstate solution + The ion concentration can be 0.1 ppm, 0.5 ppm, 1 ppm, 5 ppm, 10 ppm, or any value between 0.1 and 10 ppm, K + The ion concentration can be 0.1 ppm, 0.5 ppm, 1 ppm, 5 ppm, 10 ppm, or any value between 0.1 and 10 ppm, Ca 2+ The ion concentration can be 0.1 ppm, 0.5 ppm, 1 ppm, 5 ppm, 10 ppm, or any value between 0.1 and 10 ppm, Mg 2+ The ion concentration can be 0.1 ppm, 0.5 ppm, 1 ppm, 5 ppm, or any value between 0.1 and 5 ppm, Fe 3+ and Fe 2+ The ion concentration can be 0.1 ppm, 0.5 ppm, 1 ppm, 5 ppm, 10 ppm, or any value between 0.1 and 10 ppm, Cu 2+ The ion concentration can be 0.1 ppm, 0.5 ppm, 1 ppm, 3 ppm, or any value between 0.1 and 3 ppm. Ni 2+ The ion concentration can be 0.1 ppm, 0.5 ppm, 1 ppm, 5 ppm, or any value between 0.1 and 5 ppm. Al 3+ The ion concentration can be 0.1 ppm, 0.5 ppm, 1 ppm, 5 ppm or any value between 0.1 and 5 ppm.

[0106] It is important to note that excessively high impurity concentrations will significantly impact subsequent processes and the performance of the final product; during pyrolysis or reduction roasting, residual Na... + K +Alkali metal ions react with tungsten oxide at high temperatures to form low-melting-point compounds (such as Na₂WO₄ and K₂WO₄), leading to sintering agglomeration or material inhomogeneity; in the reduction reaction, Fe... 3+ and Fe 2+ Cu 2+ Heavy metal ions may catalyze side reactions, generating elemental metals (such as Fe and Cu), which can then mix into tungsten powder, affecting its mechanical strength. Impurities can also impact the final product: in tungsten alloy materials for nuclear fusion plasma applications, trace amounts of Na... + K + It easily melts at high temperatures, causing a liquid film to form on the tungsten surface, reducing the material's resistance to heat load; Fe 3+ and Fe 2+ Cu 2+ Impurities such as Ca can disrupt the crystal lattice integrity of tungsten, reducing its thermal conductivity. 2+ Mg 2+ Impurities such as CaO and MgO are easily oxidized at high temperatures to form CaO and MgO, which react with the tungsten matrix to form brittle tungstates (such as CaWO4), reducing the material's ductility. In addition, Ca and Mg are enriched at grain boundaries, weakening the grain boundary bonding force and leading to intergranular fracture, especially exacerbating the formation of grain boundary voids under irradiation.

[0107] It should also be noted that by controlling the impurity content within the above-mentioned range, and by optimizing subsequent processes such as vacuum spraying, freeze drying, and hydrogen reduction reaction, this application can effectively avoid the negative impact of impurities.

[0108] In some embodiments, the method for preparing submicron-sized high-purity tungsten powder satisfies at least one of the following conditions:

[0109] A. The feed flow rate of the vacuum spray is 5 mL / min-25 mL / min;

[0110] Optionally, the feed flow rate of the vacuum spray can be any value between 5 mL / min, 10 mL / min, 15 mL / min, 20 mL / min, 25 mL / min, or 5 mL / min-25 mL / min;

[0111] B. The nozzle orifice diameter of the vacuum spray is 0.5mm-1.5mm;

[0112] Optionally, the nozzle orifice diameter of the vacuum spray can be any value between 0.5mm, 1mm, 1.5mm, or 0.5mm-1.5mm;

[0113] It is important to note that the feed flow rate of vacuum spraying should be within the range of 5 mL / min to 25 mL / min, matching the atomization capability of the vacuum spray nozzle orifice diameter (0.5 mm to 1.5 mm) to ensure a concentrated droplet size distribution. If the flow rate is too low (<5 mL / min), the atomized droplets will be too small, the spraying time will be prolonged, and the efficiency will be low. If the flow rate is too high (>25 mL / min), the droplets will merge to form large particles (>100 μm). During freezing, the outer layer will freeze first, the internal moisture migration will be hindered, and residual moisture (>5%) will remain in the center of the particles after drying.

[0114] C. The freezing temperature for the freeze-drying process is -40℃ to -80℃, and the drying temperature is 40℃ to 50℃.

[0115] Optionally, the freezing temperature for freeze drying can be any value between -40℃, -50℃, -60℃, -70℃, -80℃ or -40℃--80℃, and the drying temperature can be any value between 40℃, 45℃, 50℃ or 40℃--50℃.

[0116] It is important to note that freezing temperatures below -40°C ensure a water vapor partial pressure of <1 Pa, accelerating ice crystal sublimation (sublimation rate >1 kg / h·m). 2 If the temperature is too high (> -40℃), the partial pressure of water vapor will increase (>10Pa), the sublimation rate will decrease, the drying time will be prolonged, and the escape of NH3 will cause the ammonia content of the powder to exceed the standard; if the temperature is too low (< -80℃), the refrigeration energy consumption will increase dramatically, the condenser will frost too quickly (requiring frequent defrosting), and continuous production will be interrupted.

[0117] It should also be noted that a drying temperature within the range of 40℃-50℃ can provide sufficient heat to accelerate the sublimation of ice crystals while avoiding localized overheating and decomposition of the material. At the same time, gentle heating can maintain the frozen skeleton structure and prevent pore collapse. If the temperature is too low (<40℃), the sublimation rate will be insufficient, the drying time will be prolonged, and there will be more residual moisture in the powder. If the temperature is too high (>50℃), the material surface will be overheated, causing the high-purity ammonium tungstate solution to partially decompose and generate WO3, resulting in a decrease in specific surface area.

[0118] D. During the freeze-drying process, the vacuum degree is maintained at ≤100Pa, and the vacuum degree is maintained at ≤5Pa after the drying is completed.

[0119] Optionally, the vacuum degree during the drying process can be any value of 0.1Pa, 1Pa, 10Pa, 100Pa or ≤100Pa, and the vacuum degree after drying can be any value of 0.1Pa, 1Pa, 2Pa, 3Pa, 4Pa, 5Pa or ≤5Pa.

[0120] In some embodiments, the hydrogen reduction reaction includes a first hydrogen reduction reaction and a second hydrogen reduction reaction performed sequentially.

[0121] In some embodiments, the purity of hydrogen in the hydrogen reduction reaction is ≥99.999%, which can prevent contamination by impurities. High-purity hydrogen avoids impurities such as O2 and H2O from reacting with tungsten at high temperatures to form oxides or introducing other elements (such as C and N).

[0122] The temperature of the first hydrogen reduction reaction is 600℃-650℃, the boat pushing speed is 15min / boat-30min / boat, the boat loading amount is 100g / boat-300g / boat, and the hydrogen flow rate is 2.0m³. 3 / h-3.0m 3 / h;

[0123] Optionally, the temperature of the first hydrogen reduction reaction can be any value between 600℃, 610℃, 620℃, 630℃, 640℃, 650℃, or 600℃-650℃; the boat pushing speed can be any value between 15min / boat, 20min / boat, 25min / boat, 30min / boat, or 15min / boat-30min / boat; the boat loading amount can be any value between 100g / boat, 200g / boat, 300g / boat, or 100g / boat-300g / boat; and the hydrogen flow rate can be 2.0m³. 3 / h, 2.5m 3 / h, 3.0m 3 / h or 2.0m 3 / h-3.0m 3 Any value between / h;

[0124] It is important to note that submicron-sized tungsten precursors (such as NH4) 10 H2W 12 O 42 At temperatures above 600℃, it decomposes into WO3 and gradually reduces back to WO4. 2.9 Or WO2; if the temperature is too low (<600℃), the decomposition or reduction is incomplete, and the product contains undecomposed ammonium salts or intermediate phases (such as H2WO4); if the temperature is too high (>650℃), some tungsten particles sinter, making it difficult to refine them during subsequent secondary reduction.

[0125] In addition, when the boat pushing speed is 15min / boat-30min / boat, it can ensure that the material stays in the high-temperature zone for a sufficient time to complete thermal decomposition and preliminary reduction. If the speed is too fast (<15min / boat), the material is not fully reduced, the proportion of residual WO3 increases, and the generation efficiency decreases. If the speed is too slow (>30min / boat), energy consumption increases, and the particles are slightly sintered.

[0126] Furthermore, when the loading amount is 100g / boat-300g / boat, the appropriate loading amount ensures that hydrogen permeates to the center of the boat, avoiding over-reduction of the outer layer while the inner layer remains unreacted; the single processing volume is moderate to ensure production efficiency and quality; if the loading amount is too high (>300g / boat), the reduction in the central area will be insufficient; if the loading amount is too low (<100g / boat), the production capacity will be low and the heat utilization rate will be insufficient.

[0127] It should also be noted that when the hydrogen flow rate is 2.0 m³ / s... 3 / h-3.0m 3 At a flow rate of 100 m³ / h, the reduction reaction rate (WO₃ + 3H₂ → W + 3H₂O) can be maintained, and the generated water vapor can be discharged to prevent the reverse reaction; if the H₂ flow rate is less than 2.0 m³ / h, the reduction reaction rate can be maintained. 3 / h, localized water vapor accumulation leads to the re-oxidation of WO2 (e.g., WO2 + H2O → H2WO4); if the H2 flow rate is too high (>3.0m³ / h), 3 / h, gas turbulence disturbs the powder, increasing particle dispersion loss;

[0128] The second hydrogen reduction reaction was carried out at a temperature of 850℃-950℃, with a boat pushing speed of 15min / boat-30min / boat, a boat loading capacity of 100g / boat-300g / boat, and a hydrogen flow rate of 2.5m³ / min. 3 / h-4.5m 3 / h.

[0129] Optionally, the temperature of the second hydrogen reduction reaction can be any value between 800℃, 850℃, 900℃, 950℃, or 850℃-950℃; the boat pushing speed can be any value between 15min / boat, 20min / boat, 25min / boat, 30min / boat, or 15min / boat-30min / boat; the boat loading amount can be any value between 100g / boat, 200g / boat, 300g / boat, or 100g / boat-300g / boat; and the hydrogen flow rate can be 2.0m³. 3 / h, 2.5m 3 / h, 3.0m 3 / h or 2.0m 3 / h-3.0m 3 Any value between / h.

[0130] It should be noted that when the temperature of the second hydrogen reduction reaction is 850℃-950℃, WO2 can be completely reduced to metallic tungsten (WO2+2H2→W+2H2O). If the temperature is too low (<850℃), the reduction will be incomplete, leaving WO2 residues. If the temperature is too high (>950℃), it can easily lead to grain coarsening.

[0131] In addition, when the boat pushing speed of the second hydrogen reduction reaction is 15 min / boat to 30 min / boat, it can be matched with the boat pushing speed of the first reduction to ensure that the second reduction reaction is sufficient and to avoid excessive sintering of particles at high temperature. If the speed is too fast (<15 min / boat), the reduction time is insufficient and the tungsten powder conversion rate is low. If the speed is too slow (>30 min / boat), the grains grow significantly.

[0132] Furthermore, when the loading amount of the second hydrogen reduction reaction is 100g / boat-300g / boat, the loading amount is consistent with that of the first reduction to ensure similar heat transfer and gas diffusion conditions and avoid batch differences; if the loading amount is too large (>300g / boat), the reduction in the central region will be insufficient; if the loading amount is too small (<100g / boat), the production capacity will be low and the heat utilization rate will be insufficient.

[0133] It should also be noted that when the hydrogen flow rate for the second hydrogen reduction reaction is 2.5 m³ / s... 3 / h-4.5m 3 At a flow rate of / h, a higher flow rate is needed to address the strongly exothermic reaction of the second reduction, rapidly removing water vapor and maintaining a low oxygen partial pressure; if the H2 flow rate is less than <2.5m³ / h... 3 / h, water vapor retention leads to partial oxidation of tungsten powder (WO3 formation on the surface); if the H2 flow rate is too high (>4.5m³ / h), 3 / h, airflow impact causes powder dust to be stirred up, reducing the yield.

[0134] In some embodiments, the method for preparing submicron-sized high-purity tungsten powder satisfies at least one of the following conditions:

[0135] A. After the freeze-drying process, the sample is then sieved.

[0136] B. After the hydrogen reduction reaction is carried out, a passivation treatment is also performed;

[0137] The passivation treatment includes: introducing N2 and / or Ar into the material after hydrogen reduction reaction.

[0138] It should be noted that passivation treatment can reduce the activity of submicron-sized high-purity tungsten powder, prevent tungsten powder oxidation, reduce surface energy, inhibit the agglomeration between powder particles, maintain its stability, and protect the tungsten powder from secondary oxidation. After passivation treatment, it can be vacuum-sealed.

[0139] The second aspect of this application provides a submicron-sized high-purity tungsten powder, which is prepared by the method described above.

[0140] In some embodiments, the submicron-sized high-purity tungsten powder satisfies at least one of the following conditions:

[0141] A. The purity of the submicron-grade high-purity tungsten powder is ≥99.995%;

[0142] Optionally, the purity of the submicron-grade high-purity tungsten powder can be any value of 99.995%, 99.999%, 99.9999%, 99.99999%, or ≥99.995%.

[0143] B. The particle size of the submicron-sized high-purity tungsten powder is 0.1-1 μm.

[0144] Optionally, the particle size of the submicron-sized high-purity tungsten powder can be any value of 1μm, 0.9μm, 0.5μm, 0.1μm, or 0.1-1μm.

[0145] Preferably, the particle size of the submicron-sized high-purity tungsten powder is 0.1-1 μm.

[0146] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0147] Example 1

[0148] This embodiment provides a method for preparing submicron-sized high-purity tungsten powder, the specific steps of which are as follows:

[0149] S1: Ammonium tungstate solution is prepared using an ammonia filtration process. The ammonia filtration process is as follows: the purity of ammonium paratungstate is ≥99.95%, and the content of impurity elements in the product is: Na: 12.4ppm, K: 12.8ppm, Ca: 11.6ppm, Mg: 6.3ppm, Fe: 12.8ppm, Cu: 5.2ppm, Ni: 8.7ppm, Al: 6.1ppm. The ammonia concentration is 25wt%, the mixing ratio of ammonium paratungstate and ammonia is 1g:10mL, the ammonia filtration temperature is 80℃, and the ammonia filtration pressure is 5MPa. After the ammonium paratungstate is completely dissolved, it undergoes two-stage filtration. The pore size of the primary filter paper is 3μm to remove insoluble visible precipitates, and the pore size of the secondary filter paper is 0.3μm to remove ultrafine impurity particles. The ammonium paratungstate is then sealed and stored after ammonia filtration.

[0150] S2: High-purity ammonium tungstate solution was prepared using an ion exchange process. The ion exchange process was as follows: First stage treatment: 001×7 strong acidic cation exchange resin was used; Second stage treatment: chelating Lewatit TP207 resin was used. After two stages of treatment, a high-purity ammonium tungstate solution was obtained, and the ion exchange temperature was maintained at 25℃. After ion exchange, ammonia water was added to the high-purity ammonium tungstate solution to maintain the pH of the high-purity ammonium tungstate solution at 7.9-8.1.

[0151] S3: Submicron-sized tungsten precursors were prepared using a vacuum spray freeze-drying process. The vacuum spray freeze-drying process was as follows: the raw material was a high-purity ammonium tungstate solution with a pH of 8 obtained in step S3, wherein the concentration of the ammonium tungstate solution was 5 g / L, the solution temperature was 20℃, the feed flow rate was set to 5 mL / min using a peristaltic pump, the condenser temperature was -50℃, the ice crystal sublimation heating temperature was 50℃, the vacuum degree of the vacuum environment during the sublimation process was ≤100 Pa, and the vacuum degree after sublimation drying was ≤5 Pa. The tungsten precursor powder after vacuum spray freeze-drying was passed through an 80-mesh nylon sieve. The SEM images of the tungsten precursor powder were as follows: Figure 1 As shown;

[0152] S4: Submicron-sized tungsten powder was prepared using a two-stage hydrogen reduction process. The two-stage hydrogen reduction process was as follows: the tungsten precursor powder was subjected to two-stage hydrogen reduction, maintaining a hydrogen purity of ≥99.999%. The first hydrogen reduction temperature was 620℃, the boat pushing speed was 30 min / boat, the boat loading amount was 200 g / boat, and the hydrogen flow rate was 2.5 m³ / min. 3 Tungsten oxide powder, mainly WO2, was obtained by passing it through an 80-mesh sieve at a rate of 1 h / h. The sieved material was then subjected to a secondary hydrogen reduction at 920℃, a boat pushing speed of 30 min / boat, a boat loading of 200 g / boat, and a hydrogen flow rate of 4.5 m³ / h. 3 / h, submicron-sized high-purity tungsten powder was obtained and passed through an 80-mesh sieve. The SEM image of this submicron-sized high-purity tungsten powder is shown below. Figure 2 As shown;

[0153] S5: Submicron-sized tungsten powder is preserved by passivation treatment and vacuum packaging. The passivation treatment process is as follows: submicron-sized high-purity tungsten powder is passed through N2 containing 99.999% purity to reduce its activity and protect the tungsten powder from secondary oxidation. After passivation treatment, it is vacuum packaged.

[0154] Example 2

[0155] The difference from Example 1 is as follows: The ion exchange process is as follows: First-stage treatment: a strong acid 001×7 cation exchange resin is selected; Second-stage treatment: a chelating Lewatit TP207 resin is selected, and after ion exchange, ammonia water is added to the high-purity ammonium tungstate solution to maintain the pH of the high-purity ammonium tungstate solution at 7.0-7.3.

[0156] Example 3

[0157] The difference from Example 1 is as follows: the two-stage hydrogen reduction process involves two-stage hydrogen reduction of the tungsten precursor powder, with a reduction temperature of 650°C, a boat pushing speed of 30 min / boat, a boat loading amount of 200 g / boat, and a hydrogen flow rate of 2.5 m³ / min. 3Tungsten oxide powder, mainly WO2, was obtained by passing it through an 80-mesh sieve at a rate of 1 h / h. The sieved material was then subjected to a secondary reduction at 950℃, a boat-pushing speed of 30 min / boat, a boat load of 200 g / boat, and a hydrogen flow rate of 4.5 m³ / h. 3 / h.

[0158] Comparative Example 1

[0159] The difference from Example 1 is that no primary ion exchange treatment is performed.

[0160] Comparative Example 2

[0161] The difference from Example 1 is that no secondary ion exchange treatment is performed.

[0162] Comparative Example 3

[0163] The difference from Example 1 is that the order of the primary ion exchange resin and the secondary ion exchange resin is changed.

[0164] Comparative Example 4

[0165] The difference from Example 1 is that after ion exchange, ammonia water is not used to adjust the pH value, and the pH value of the high-purity ammonium tungstate solution subjected to vacuum spraying is 2.5-5.5.

[0166] Comparative Example 5

[0167] The difference from Example 1 is that step S3 is not performed in a vacuum, but in an atmospheric pressure environment.

[0168] Comparative Example 6

[0169] The difference from Example 1 is that the first hydrogen reduction reaction is not carried out; instead, a second hydrogen reduction is used directly for preparation.

[0170] The impurity content in the high-purity ammonium tungstate solutions prepared in the above embodiments and comparative examples is shown in Table 1.

[0171] Table 1. Impurity content (ppm) in high-purity ammonium tungstate solution

[0172]

[0173] The purity and particle size of the submicron-sized high-purity tungsten powder prepared in the above embodiments and comparative examples are shown in Table 2.

[0174] Purity testing was conducted according to GB / T 3458-2006 "Tungsten Powder," using ICP-MS (Inductively Coupled Plasma Mass Spectrometry) to determine the content of impurity elements in the tungsten powder. Particle size testing was conducted according to GB / T 19077-2016 "Particle Size Distribution - Laser Diffraction Method Using Laser Particle Size Analyzer."

[0175] Table 2 Purity and Particle Size of Submicron-Grade High-Purity Tungsten Powder

[0176]

[0177] analyze:

[0178] As demonstrated by the above experiments and Example 1, the use of two-stage filtration, combined with 001×7 strong acid cation exchange resin and chelating Lewatit TP207 resin, can effectively remove insoluble particles and metal cation impurities from the solution, yielding a high-purity tungsten precursor solution. The tungsten precursor solution can then be processed by vacuum spray freeze-drying and a two-stage hydrogen reduction process to prepare 4N5 grade high-purity submicron tungsten powder.

[0179] As shown in Example 2, if a weakly acidic D113 cation exchange resin is used instead of a strongly acidic 001×7 cation exchange resin, the Ca in the ammonium tungstate solution will decrease. 2+ Mg 2+ Its removal effect is better than that of strong acid 001×7 cation exchange resin, but for other substances such as Na+, it is not as effective. + K + Fe 2+ and Fe 3+ Cu 2+ Ni 2+ Al 3+ The removal effect was weak. The purity of the tungsten powder obtained in the final product was reduced, and the particle size was increased.

[0180] As shown in Example 3, increasing the primary and secondary reduction temperatures can reduce the content of highly volatile alkali metal impurities such as K, Na, Ca, and Mg, while having a smaller impact on impurity elements such as Fe, Cu, Ni, and Al. The final tungsten powder obtained has higher purity, but the particle size is larger.

[0181] Comparative Examples 1 and 2 show that without primary or secondary ion exchange, the content of all impurity elements in the prepared tungsten powder increases significantly, the purity decreases, and the particle size increases. This indicates that the simple cation exchange process has limited adsorption capacity for metallic impurities, and two or more stages are needed to achieve better impurity removal.

[0182] As shown in Comparative Example 3, changing the order of the primary and secondary ion exchange resins reduces the amount of Na in the ammonium tungstate solution. + K + Al 3+ With increased content, Ca 2+ Mg 2+ The content is similar, Fe 2+ and Fe 3+ Cu 2+ Ni 2+The content decreased. The purity of the tungsten powder obtained in the final preparation was slightly reduced, and the particle size of the tungsten powder was slightly increased.

[0183] As shown in Comparative Example 4, after ion exchange, if ammonia is not used to adjust the pH, the content of all impurity elements in the ammonium tungstate solution increases significantly. This is mainly because after ion exchange with a strong acid or chelating resin, the solution pH is usually acidic. Under acidic conditions, ammonium tungstate gradually hydrolyzes to generate metatungstate and release NH4. + Further lowering the pH can increase acidity, potentially damaging the complex structure, leading to precipitation and decreased stability. In acidic environments, the adsorption capacity of strongly acidic cation exchange resins and chelating exchange resins for metal cations decreases, resulting in lower purity and larger particle size of the final tungsten powder.

[0184] As shown in Comparative Example 5, spray freeze-drying under normal pressure significantly increases the content of all impurity elements in the ammonium tungstate solution. Under normal pressure, NH3 in the solution is more volatile, leading to a decrease in pH. Ammonium tungstate partially hydrolyzes into metatungstate or tungstate, initiating precipitation. Under normal pressure, water evaporation is slow, and residual Na... + K + As water migrates to the surface of the droplets, it forms soluble salts (such as K₂WO₄ and Na₂WO₄), which cannot be effectively removed, ultimately increasing the residual amount; Ca 2+ Mg 2+ With WO4 2- The formation of slightly soluble salts during drying results in co-precipitation, but ice crystal growth is slow under normal pressure, leading to uneven precipitation distribution and some crystals being encapsulated within the particles. Increased acidity (decreased pH) promotes Al... 3+ Fe 3+ Hydrolysis produces colloids (Al(OH), Fe(OH)3), which adsorb onto the surface of ammonium tungstate particles and are difficult to remove through subsequent reduction. The freezing rate at atmospheric pressure is low (compared to vacuum), leading to increased ice crystal size and reduced porosity of the precursor particles after drying. This hinders mass transfer during reduction, resulting in grain coarsening. Consequently, the purity and particle size of the final tungsten powder are reduced.

[0185] As shown in Comparative Example 6, skipping the first hydrogen reduction reaction and directly using the second hydrogen reduction causes low-boiling-point impurities (such as K, Na, Ca, and Mg) to lose their opportunity to volatilize at low temperatures, resulting in increased residues. Direct second reduction exposes the precursor directly to high temperatures, leading to instantaneous decomposition and reduction, rapid particle sintering, and increased grain size, resulting in decreased purity and increased particle size of the final tungsten powder.

[0186] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0187] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the foregoing claims, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for preparing submicron-sized high-purity tungsten powder, characterized in that, include: Ammonium paratungstate and ammonia water are mixed to obtain a mixture, and the mixture is subjected to ammonia dissolution treatment and filtered to obtain a first ammonium paratungstate solution; The first ammonium tungstate solution was subjected to a first ion exchange using a strong acid cation exchange resin to obtain a solution after the first ion exchange. The solution after the first ion exchange was subjected to a second ion exchange using a chelating resin to obtain a high-purity ammonium tungstate solution. The high-purity ammonium tungstate solution was subjected to vacuum spraying and freeze-drying to obtain a submicron-sized tungsten precursor. The submicron-sized tungsten precursor was subjected to a hydrogen reduction reaction to obtain submicron-sized high-purity tungsten powder. The strongly acidic cation exchange resin includes a strongly acidic 001×7 cation exchange resin. The chelating resin includes chelating Lewatit TP207 resin; The hydrogen reduction reaction includes a first hydrogen reduction reaction and a second hydrogen reduction reaction performed sequentially. The temperature of the first hydrogen reduction reaction is 600℃-650℃, the boat pushing speed is 15min / boat-30min / boat, the boat loading amount is 100g / boat-300g / boat, and the hydrogen flow rate is 2.0m³. 3 / h-3.0m 3 / h; The second hydrogen reduction reaction was carried out at a temperature of 850℃-950℃, with a boat pushing speed of 15min / boat-30min / boat, a boat loading capacity of 100g / boat-300g / boat, and a hydrogen flow rate of 2.5m³ / min. 3 / h-4.5m 3 / h.

2. The method for preparing submicron-sized high-purity tungsten powder according to claim 1, characterized in that, At least one of the following conditions must be met: A. The purity of the ammonium paratungstate is ≥99.95%; B. The mass concentration of the ammonia solution is 5%-25%; C. The solid-liquid ratio of the ammonium paratungstate and the ammonia solution is 1g:5mL-10mL; D. The temperature of the ammonia solvent treatment is 60℃-90℃, and the pressure is 5MPa-10MPa; E. The filtration includes a first filtration and a second filtration performed sequentially; The filter paper of the first filter has a pore size of 3μm-5μm; The filter paper of the second filter has a pore size of 0.2μm-0.5μm.

3. The method for preparing submicron-sized high-purity tungsten powder according to claim 1, characterized in that, At least one of the following conditions must be met: A. The temperatures of the first ion exchange and the second ion exchange are each independently between 20℃ and 60℃; B. After the second ion exchange, the pH value of the high-purity ammonium tungstate solution is adjusted with ammonia.

4. The method for preparing submicron-sized high-purity tungsten powder according to claim 3, characterized in that, The pH value is 7-9.

5. The method for preparing submicron-sized high-purity tungsten powder according to claim 1, characterized in that, At least one of the following conditions must be met: A. The concentration of the high-purity ammonium tungstate solution is 5 g / L-20 g / L; B. The temperature of the high-purity ammonium tungstate solution is 20℃-30℃; C. Na in the high-purity ammonium tungstate solution + Ion concentration is 0.1-10 ppm, K + The ion concentration is 0.1-10 ppm, Ca 2+ The ion concentration is 0.1-10 ppm, Mg 2+ The ion concentration is 0.1-5 ppm, Fe 3+ and Fe 2+ The ion concentration is 0.1-10 ppm, Cu 2+ The ion concentration is 0.1-3 ppm, Ni 2+ The ion concentration is 0.1-5 ppm, Al 3+ The ion concentration is 0.1-5 ppm.

6. The method for preparing submicron-sized high-purity tungsten powder according to claim 1, characterized in that, At least one of the following conditions must be met: A. The feed flow rate of the vacuum spray is 5 mL / min-25 mL / min; B. The nozzle orifice diameter of the vacuum spray is 0.5 mm-1.5 mm; C. The freezing temperature for the freeze-drying process is -40℃ to -80℃, and the drying temperature is 40℃ to 50℃. D. During the freeze-drying process, the vacuum degree is maintained at ≤100Pa, and the vacuum degree is maintained at ≤5Pa after the drying is completed.

7. The method for preparing submicron-sized high-purity tungsten powder according to any one of claims 1-6, characterized in that, At least one of the following conditions must be met: A. After the freeze-drying process, the sample is then sieved. B. After the hydrogen reduction reaction is carried out, a passivation treatment is also performed; The passivation treatment includes: introducing N2 and / or Ar into the material after hydrogen reduction reaction.

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