Method for reducing refractory metal oxide by using metal vapor
Through the reaction to the reduction of the granular and metal vapor of the difficulty melting metal oxides, the reaction temperature is difficult to control, the product shape and the high oxygen content in the existing powder preparation process are solved, and the efficient and uniform powder preparation is achieved. Essence
Patent Information
- Application Number
- CN202411831405.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-12
- Publication Date
- 2025-01-24
AI Technical Summary
In the existing niobium powder preparation technology, the aluminum-thermal self-propagation method and the magnesium-thermal reduction method have problems such as high reaction temperature, uneven product morphology, and high oxygen content, which lead to adverse phenomena.
By gallery the difficult melting metal oxides, a small spherical powder with uniform pores is formed, and metal vapor reaction reactions are performed in an inert atmosphere. Metal vapor is fully exposed to oxide to avoid pollution and high temperature oxidation.
Efficient reduction of refractory metal oxides with low oxygen content is achieved, and the obtained niobium powder particles are relatively uniform in size, with less fine powder attached to the surface, avoiding the "sandwich" phenomenon, and improving the quality and application value of the powder.
Smart Images
Figure HDA0005185644430000011 
Figure HDA0005185644430000021 
Figure HDA0005185644430000031
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of metal smelting, and in particular relates to a method for reducing refractory metal oxides with metal vapor. Background Art
[0002] Niobium metal is a highly refractory metal with a melting point of up to 2468°C. It has strong corrosion resistance and is a good superconductor. It has important applications in aerospace, automotive, and defense industries. Among the existing niobium powder preparation processes, only the aluminum heat self-propagating method and the magnesium heat reduction method have achieved industrial application.
[0003] In the thermite self-propagating method, Nb2O5, Al, a heating agent and a slag-forming agent are mixed and ignited uniformly to react to obtain niobium aluminum alloy and slag. The obtained alloy is horizontally smelted, and aluminum and other impurities are removed by electron beam melting and other methods to obtain niobium ingots, which are then hydrogenated and crushed to obtain niobium powder. In order to further obtain low-oxygen niobium powder, magnesium reduction is often performed on it. This process route and equipment are relatively mature. However, the reaction temperature of the thermite self-propagating method is high and difficult to control. While electron beam melting removes aluminum in the product niobium, metallic niobium is melted into niobium ingots, which are then hydrogenated and crushed into powders with uneven shapes, irregular block sizes, a large amount of fine powder attached to the surface, and a wide range of particle size distribution. The high oxygen content in niobium can easily lead to undesirable phenomena such as "sandwich" in the niobium ingots, and the core of the niobium ingot is difficult to crush into powder.
[0004] The magnesium thermal reduction process was first developed by the German company Stark to prepare tantalum powder. The process involves the reaction of gaseous magnesium evaporated at 800°C with tantalum oxide. The reduced product is washed with dilute acid and deoxidized to form a tantalum powder with a specific surface area of 5 to 13 m2. 2 / g of tantalum powder, which has the advantages of high specific volume, adjustable particle morphology and pore size distribution. However, the magnesium thermal reduction method must be carried out at a relatively high temperature. The evaporation of magnesium is severely restricted by temperature, and rapid evaporation and reaction of magnesium cannot be achieved at low temperatures; the evaporated magnesium stays in the material layer for a short time and cannot fully react with the oxide, resulting in a large consumption of magnesium and no recovery; during the reaction, fine particles of metallic magnesium condense on the inner surface of the reactor, making it difficult to remove the fine metallic magnesium particles. Summary of the invention
[0005] In view of this, some embodiments disclose a method for reducing refractory metal oxides with metal vapor, comprising:
[0006] Granulating the refractory metal oxide to form refractory metal oxide powder, wherein the powder particles are small spheres with uniform pores inside;
[0007] The refractory metal oxide powder is evenly spread in the first reaction vessel with a thickness of 2 to 50 mm, wherein a plurality of through holes are evenly opened at the bottom of the first reaction vessel;
[0008] Evenly laying the reducing metal in the second reaction vessel, wherein the amount of the reducing metal added is 1 to 5 times the theoretical molar amount of the reduced refractory metal oxide;
[0009] The first reaction vessel is placed on the second reaction vessel and then placed into a reaction furnace, wherein an inert gas inlet is provided at one end of the reaction furnace and a condensation collector is provided at the other end of the reaction furnace;
[0010] Inert gas is introduced into the reaction furnace, and the reaction furnace is heated to 650-1200° C. in an inert atmosphere, and kept warm for 1-8 hours, so that the reduced metal in the second reaction dish evaporates into metal vapor, enters the first reaction dish through the through hole at the bottom of the first reaction dish, and then enters the interior of the refractory metal oxide powder through the pores of the refractory metal oxide powder, undergoes a reduction reaction with the refractory metal oxide, and obtains a refractory metal oxide with a low oxygen content;
[0011] The obtained low-oxygen-content refractory metal oxide is ground, purified by acid washing, dried, and then evenly laid in a first reaction vessel;
[0012] Evenly laying the reducing metal in the second reaction vessel, wherein the amount of the reducing metal added is 1 to 5 times the theoretical molar amount of the reduced low-oxygen refractory metal oxide;
[0013] The first reaction dish is placed on the second reaction dish, and then put into a reaction furnace, heated to 650-1200° C. in an inert atmosphere, and kept warm for 0.5-6 hours, the reduced metal in the second reaction dish evaporates into metal vapor, enters the first reaction dish through the through hole at the bottom of the first reaction dish, and then enters the interior of the low-oxygen-content refractory metal oxide through the pores of the low-oxygen-content refractory metal oxide, undergoes a reduction reaction with the low-oxygen-content refractory metal oxide, and obtains a refractory metal crude product;
[0014] The crude refractory metal product is ground, purified by acid washing, and dried to obtain refractory metal powder.
[0015] In the method for reducing refractory metal oxides with metal vapor disclosed in some embodiments, the particle size of the refractory metal oxide powder is 10 to 80 μm.
[0016] In the method for reducing refractory metal oxides with metal vapor disclosed in some embodiments, the diameter of the through hole opened at the bottom of the first reaction vessel is 0.05-1.5 mm.
[0017] Some embodiments disclose a method for reducing a refractory metal oxide with metal vapor, wherein the refractory metal oxide is Ta2O5, Nb2O5, TiO2 or V2O5.
[0018] In the method for reducing refractory metal oxides with metal vapor disclosed in some embodiments, the reducing metal is a combination of one or more of magnesium, calcium, and aluminum.
[0019] In some embodiments, the method for reducing refractory metal oxides with metal vapor is disclosed, wherein the reducing metal is in the form of powder, chips or particles.
[0020] In some embodiments of the method for reducing refractory metal oxides with metal vapor, the inert gas is argon.
[0021] In the method for reducing refractory metal oxides with metal vapor disclosed in some embodiments, the material of the first reaction vessel is nickel-based alloy, ceramic, heat-resistant steel or the same metal as the refractory metal oxide.
[0022] In the method for reducing refractory metal oxides with metal vapor disclosed in some embodiments, the second reaction vessel is made of nickel-based alloy, ceramic, heat-resistant steel or the same metal as the refractory metal oxide.
[0023] In the method for reducing refractory metal oxides with metal vapor disclosed in some embodiments, the acid solution used in the acid washing and purification process is a combination of one or more of HCl, HNO3, and H2SO4.
[0024] The method for reducing refractory metal oxides with metal vapor disclosed in the embodiment of the present invention comprises: a first reaction vessel having a plurality of through holes at the bottom thereof, and metal vapor formed by reducing metal in the second reaction vessel enters the first reaction vessel through the plurality of through holes at the bottom thereof, and is in full contact with the refractory metal oxide; during the reduction process, the first reaction vessel and the second reaction vessel are respectively provided with refractory metal oxide and reducing metal, so that the refractory metal oxide is prevented from being contaminated by the reducing metal; the refractory metal oxide is granulated before the reaction to form particles with a large number of pores, so that the contact area between the refractory metal oxide and the metal vapor is increased, and the residence time of the metal vapor in the material layer is prolonged, so that the reaction can be fully carried out to improve the reduction efficiency; argon gas is introduced during the reduction process to avoid high-temperature oxidation of the product, and at the same time, the excess metal vapor is blown to a condensation collector for collection by argon gas, so that the waste of raw materials is avoided and resources are saved. The method for reducing refractory metal oxides with metal vapor disclosed in the embodiment of the present invention comprises: a simple reduction process and a generally applicable device. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 Example 1 SEM image of Ta2O5 after granulation;
[0026] Figure 2 XRD pattern of tantalum powder of Example 1;
[0027] Figure 3 SEM image of tantalum powder of Example 1;
[0028] Figure 4 Example 2 Schematic diagram of the reaction device;
[0029] Figure 5 Comparative Example 1 SEM image of tantalum powder;
[0030] Figure 6 XRD pattern of niobium powder of comparative example 2;
[0031] Figure 7 SEM image of niobium powder of Comparative Example 2;
[0032] Figure 8 SEM image of niobium monoxide of Comparative Example 3.
[0033] Reference numerals
[0034] 1 First reaction vessel 2 Second reaction vessel
[0035] 3 Reactor 100 Refractory Metal Oxides
[0036] 200 Reduced Metal DETAILED DESCRIPTION
[0037] The word "embodiment" used here as an "exemplary" does not necessarily mean that any embodiment described is superior to or better than other embodiments. Unless otherwise specified, the performance index tests in the embodiments of this application are performed using conventional test methods in the art. It should be understood that the terms described in this application are only used to describe specific implementation methods and are not used to limit the content disclosed in this application.
[0038] Unless otherwise specified, the technical and scientific terms used in this document have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs; other experimental methods and technical means not specifically specified in this application refer to experimental methods and technical means commonly used by ordinary technicians in this field.
[0039] The terms "substantially" and "approximately" used herein are used to describe small fluctuations. For example, they can refer to less than or equal to ±5%, such as less than or equal to ±2%, such as less than or equal to ±1%, such as less than or equal to ±0.5%, such as less than or equal to ±0.2%, such as less than or equal to ±0.1%, such as less than or equal to ±0.05%. The numerical data represented or presented in the range format herein are used only for convenience and brevity, and should therefore be flexibly interpreted as including not only the values clearly listed as the limits of the range, but also all independent values or sub-ranges contained in the range. For example, the numerical range of "1-5%" should be interpreted as including not only the clearly listed values of 1% to 5%, but also the independent values and sub-ranges within the range shown. Therefore, independent values such as 2%, 3.5% and 4% and sub-ranges such as 1%-3%, 2%-4% and 3%-5% are included in this numerical range. This principle also applies to the range of only one numerical value. In addition, such an interpretation applies regardless of the width of the range or the characteristics described.
[0040] In this document, including in the claims, transitional words such as "comprises," "includes," "with," "having," "containing," "involving," "accommodating," etc. are understood to be open-ended, i.e., meaning "including but not limited to." Only the transitional words "consisting of" and "composed of" are closed transitional words.
[0041] In order to better illustrate the content of the present application, numerous specific details are provided in the specific examples below. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In the embodiments, some methods, means, instruments, equipment, etc. well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present application.
[0042] Under the premise of no conflict, the technical features disclosed in the embodiments of the present application can be arbitrarily combined, and the obtained technical solutions belong to the contents disclosed in the embodiments of the present application. It should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like mentioned in the present application indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the technical features and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention, unless it conflicts with the context. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance, unless it conflicts with the context.
[0043] The refractory metal oxide is granulated to form a refractory metal oxide powder. The powder particles are small spherical bodies with uniform pores inside, and the particle size is 10 - 80 μm. The refractory metal oxide powder with uniform pores can increase the contact area between the refractory metal oxide and the reducing metal during the subsequent reaction process, enabling the reaction to proceed fully. Generally, the refractory metal oxide is Ta2O5, Nb2O5, TiO2 or V2O5.
[0044] The refractory metal oxide powder is evenly laid in the first reaction dish, and the laying thickness is 2 - 50 mm, preferably 10 - 30 mm. Among them, the bottom of the first reaction dish is evenly provided with a plurality of through holes, and the aperture of the through holes is 0.05 - 1.5 mm. The first reaction dish is connected to the internal cavity of the second reaction dish through the plurality of through holes at its bottom. The aperture size of the through holes can ensure that the metal vapor in the second reaction dish can pass through smoothly and enter the first reaction dish, and can also prevent the reduction reaction products from falling into the second reaction dish.
[0045] The reducing metal is evenly laid in the second reaction dish. Among them, the addition amount of the reducing metal is 1 - 5 times the theoretical molar amount for reducing the refractory metal oxide, so that the refractory metal oxide can be fully reduced by the reducing metal.
[0046] The first reaction dish is placed on the second reaction dish and then sent into the reaction furnace. Among them, one end of the reaction furnace is provided with an inert gas inlet, and the other end of the reaction furnace is provided with a condensation collector. The condensation collector is used to collect the excess metal vapor during the reduction reaction. When the excess metal vapor passes through the first reaction dish, it will be blown by the inert gas into the condensation collector for collection, which can avoid the metal vapor condensing and adhering to the furnace wall of the reaction furnace and being difficult to clean, and can also save the usage amount of the reducing metal.
[0047] An inert gas is introduced into the reaction furnace. Under an inert atmosphere, the reaction furnace is heated to 650 - 1200 °C and kept warm for 1 - 8 h. The reducing metal in the second reaction dish evaporates into metal vapor, enters the first reaction dish through the through holes at the bottom of the first reaction dish, and then enters the interior of the refractory metal oxide powder through the pores of the refractory metal oxide powder, and reacts with the refractory metal oxide to obtain a refractory metal oxide MO with low oxygen content x , M can be Ta, Nb, Ti, V, 0.05 < x < 0.2; Usually during the reaction process, the products generated by the reaction of the metal vapor with the refractory metal oxide, such as the refractory metal obtained by reduction, the low-valent refractory metal oxide, the metal oxide obtained by oxidation, etc. will cover the surface of the unreacted refractory metal oxide, forming a protective film to hinder the further contact reaction of the metal vapor with the internal refractory metal oxide. Therefore, the refractory metal oxide product with low oxygen content obtained from this reduction reaction needs to be pickled.
[0048] The obtained low-oxygen refractory metal oxide product is ground, acid-washed, purified, and dried, and then evenly laid in the first reaction vessel; usually, during the acid-washing and purification process, impurities such as the oxidized metal oxide can be removed; and then the low-oxygen refractory metal oxide product with impurities removed is once again placed in the first reaction vessel for secondary reduction;
[0049] Evenly laying the reducing metal in the second reaction vessel, wherein the amount of the reducing metal added is 1 to 5 times the theoretical molar amount of the refractory metal oxide with low oxygen content, so that the refractory metal oxide can be fully reduced by the reducing metal;
[0050] The first reaction dish is placed on the second reaction dish, and then put into a reaction furnace, heated to 650-1200° C. in an inert atmosphere, and kept warm for 0.5-6 hours, the reduced metal in the second reaction dish evaporates into metal vapor, enters the first reaction dish through the through hole at the bottom of the first reaction dish, and then enters the interior of the low-oxygen-content refractory metal oxide through the pores of the low-oxygen-content refractory metal oxide, undergoes a reduction reaction with the low-oxygen-content refractory metal oxide, and obtains a refractory metal crude product;
[0051] The crude refractory metal product is ground, purified by acid washing, and dried to obtain refractory metal powder.
[0052] Generally, when the first reaction vessel is placed on the second reaction vessel, the connection between the first reaction vessel and the second reaction vessel needs to be sealed to prevent metal vapor from leaking out from the connection between the two, causing a waste of raw materials and affecting the progress of the reaction.
[0053] In some embodiments, the reducing metal is a combination of one or more of magnesium, calcium, and aluminum, preferably metallic magnesium.
[0054] In some embodiments, the reduced metal is in the form of powder, chips, or granules.
[0055] In some embodiments, the flow rate of the inert gas is 50 to 250 mL / min.
[0056] In some embodiments, the inert gas is argon.
[0057] In some embodiments, the first reaction vessel and the second reaction vessel are made of nickel-based alloy, ceramic, heat-resistant steel or the same metal as the refractory metal oxide. The first reaction vessel and the second reaction vessel are preferably made of the same metal as the refractory metal oxide, for example, tantalum is used for tantalum oxide and niobium is used for niobium oxide; tantalum and niobium are high temperature resistant metals with extremely high corrosion resistance and thermal stability.
[0058] In some embodiments, the acid solution used in the acid washing purification process is a combination of one or more of HCl, HNO3, and H2SO4. Generally, the amount of the acid solution added is more than 1 times the theoretical amount of acid washing purification, and the acid solution is used to wash away the reduced metal oxides attached to the reduction product, such as MgO, CaO, Al2O3, etc.
[0059] The technical details are further illustrated below in conjunction with embodiments.
[0060] Example 1
[0061] Figure 1 is a SEM image of the granulated Ta2O5 disclosed in Example 1; Figure 2 is the XRD pattern of the tantalum powder disclosed in Example 1; Figure 3 This is the SEM image of the tantalum powder disclosed in Example 1.
[0062] Example 1 discloses a method for reducing Ta2O5 by metal vapor, comprising:
[0063] The Ta2O5 is granulated to form Ta2O5 powder, such as Figure 1 As shown, the powder particles are small spheres with uniform pores inside;
[0064] Evenly spread 3g Ta2O5 powder in the first reaction vessel;
[0065] Evenly spread 6 g of magnesium powder in the second reaction vessel;
[0066] The first reaction vessel is placed on the second reaction vessel and then placed into the reaction furnace;
[0067] Argon gas at a flow rate of 200 mL / min was introduced into the reaction furnace, and the reaction furnace was heated to 900° C. under argon gas and kept warm for 3 hours to obtain tantalum oxide with low oxygen content;
[0068] The obtained low-oxygen-content tantalum oxide is ground, acid-washed, purified, and dried, and then evenly laid in a first reaction vessel;
[0069] Evenly spread magnesium powder in the second reaction vessel, wherein the amount of magnesium powder added is 4 times the theoretical molar amount of tantalum oxide with low oxygen content reduced;
[0070] The first reaction vessel was placed on the second reaction vessel, and then placed in a reaction furnace, heated to 900° C. under an argon gas flow rate of 200 mL / min, and kept warm for 1.5 h to obtain crude tantalum;
[0071] The crude tantalum is ground, purified by acid washing, and dried to obtain tantalum powder; Figure 2 As shown, it can be seen that the product is pure tantalum powder, such as Figure 3As shown, the particle size of tantalum powder is relatively uniform.
[0072] Example 2
[0073] Figure 4 This is a schematic diagram of the reaction apparatus disclosed in Example 2.
[0074] like Figure 4 As shown in (a), the reaction device includes a reaction vessel group, which consists of a first reaction vessel 1 and a second reaction vessel 2, wherein the first reaction vessel 1 is arranged on the second reaction vessel 2, and the two are sealed and connected, and a plurality of through holes (not shown in the figure) are opened at the bottom of the first reaction vessel 1;
[0075] When the refractory metal oxide is subjected to a reduction reaction, the reducing metal 200 is placed in the second reaction vessel 2, the refractory metal oxide 100 is placed in the first reaction vessel 1, and then the first reaction vessel 1 is placed on the second reaction vessel 2. Figure 4 (b); then it is sent into the reaction furnace 3 to carry out the reduction reaction of the refractory metal oxide and the reducing metal, such as Figure 4 (c) as shown; generally, a plurality of reaction vessel groups consisting of a first reaction vessel 1 and a second reaction vessel 2 can be arranged in the reaction furnace 3.
[0076] Comparative Example 1
[0077] Figure 5 This is the SEM image of the tantalum powder disclosed in Comparative Example 1.
[0078] Comparative Example 1 discloses a method for reducing Ta2O5 by metal vapor, comprising:
[0079] Evenly spread 3g Ta2O5 in the first reaction vessel;
[0080] Evenly spread 6 g of magnesium powder in the second reaction vessel;
[0081] The first reaction vessel is placed on the second reaction vessel and then placed into the reaction furnace;
[0082] Argon gas at a flow rate of 200 mL / min was introduced into the reaction furnace, and the reaction furnace was heated to 900° C. under argon gas and kept warm for 3 hours to obtain tantalum oxide with low oxygen content;
[0083] The obtained low-oxygen-content tantalum oxide is ground, acid-washed, purified, and dried, and then evenly laid in a first reaction vessel;
[0084] Evenly spread magnesium powder in the second reaction vessel, wherein the amount of magnesium powder added is 4 times the theoretical molar amount of tantalum oxide with low oxygen content reduced;
[0085] The first reaction vessel was placed on the second reaction vessel, and then placed in a reaction furnace, heated to 900° C. under an argon gas flow rate of 200 mL / min, and kept warm for 1.5 h to obtain crude tantalum;
[0086] The crude tantalum is ground, purified by acid washing, and dried to obtain tantalum powder, such as Figure 5 It can be seen that a large number of small particles are attached to the surface of the obtained tantalum powder.
[0087] Comparative Example 2
[0088] Figure 6 is the XRD pattern of the niobium powder disclosed in Comparative Example 2; Figure 7 This is the SEM image of the niobium powder disclosed in Comparative Example 2.
[0089] Comparative Example 2 discloses a method for reducing Nb2O5 by metal vapor, comprising:
[0090] Evenly spread 5 g of Nb2O5 in the first reaction vessel;
[0091] Evenly spread 9.14 g of magnesium powder in the second reaction vessel;
[0092] The first reaction vessel is placed on the second reaction vessel and then placed into the reaction furnace;
[0093] The reaction furnace was introduced with argon gas at a flow rate of 200 mL / min, and the reaction furnace was heated to 1000° C. under argon gas and kept at this temperature for 5 hours to obtain niobium oxide with low oxygen content;
[0094] The obtained low-oxygen-content niobium oxide is ground, purified by acid washing, and dried, and then evenly laid in a first reaction vessel;
[0095] Evenly spread magnesium powder in the second reaction vessel, wherein the amount of magnesium powder added is 4 times the theoretical molar amount of reducing low-oxygen niobium oxide;
[0096] The first reaction vessel is placed on the second reaction vessel, and then placed into a reaction furnace, and heated to 1000° C. under an argon gas flow rate of 200 mL / min, and kept warm for 1.5 hours to obtain crude niobium;
[0097] The crude niobium is ground, purified by acid washing, and dried to obtain niobium powder. Figure 6 As shown, it can be seen that the product is pure niobium powder, such as Figure 7 As shown, the particle size of niobium powder is relatively large, the sintering phenomenon is more obvious, and small particles of fine powder are attached to the surface.
[0098] Comparative Example 3
[0099] Figure 8 This is the SEM image of niobium monoxide disclosed in Comparative Example 3.
[0100] Comparative Example 3 discloses a method for reducing Nb2O5 by metal vapor, comprising:
[0101] Evenly spread 5g Nb2O5 in the first reaction vessel;
[0102] Evenly spread 6 g of magnesium powder in the second reaction vessel;
[0103] The first reaction vessel is placed on the second reaction vessel and then placed into the reaction furnace;
[0104] The reaction furnace was introduced with argon gas at a flow rate of 200 mL / min, and the reaction furnace was heated to 900°C under argon gas and kept warm for 2 hours to obtain the product, which was then ground, acid-washed, purified, and dried to obtain niobium monoxide powder. Figure 8 As shown, the particle size of niobium monoxide is small, and fine powder of smaller particles is attached to the surface.
[0105] In summary, by comparing Example 1 and Comparative Examples 1 to 3, it can be seen that by granulating the refractory metal oxide before the reaction, a refractory metal powder with a relatively uniform particle size can be obtained after the reaction.
[0106] The method for reducing refractory metal oxides with metal vapor disclosed in the embodiment of the present invention comprises: a first reaction vessel having a plurality of through holes at the bottom thereof, and metal vapor formed by reducing metal in the second reaction vessel enters the first reaction vessel through the plurality of through holes at the bottom thereof, and is in full contact with the refractory metal oxide; during the reduction process, the first reaction vessel and the second reaction vessel are respectively provided with refractory metal oxide and reducing metal, so that the refractory metal oxide is prevented from being contaminated by the reducing metal; the refractory metal oxide is granulated before the reaction to form particles with a large number of pores, so that the contact area between the refractory metal oxide and the metal vapor is increased, and the residence time of the metal vapor in the material layer is prolonged, so that the reaction can be fully carried out to improve the reduction efficiency; argon gas is introduced during the reduction process to avoid high-temperature oxidation of the product, and at the same time, the excess metal vapor is blown to a condensation collector for collection by argon gas, so that the waste of raw materials is avoided and resources are saved. The method for reducing refractory metal oxides with metal vapor disclosed in the embodiment of the present invention comprises: a simple reduction process and a generally applicable device.
[0107] The technical solutions disclosed in the present invention and the technical details disclosed in the embodiments are merely illustrative of the inventive concept of the present invention and do not constitute a limitation on the technical solutions of the present invention. Any conventional changes, substitutions or combinations of the technical details disclosed in the embodiments of the present invention have the same inventive concept as the present invention and are within the protection scope of the claims of the present invention.
Claims
1. A method for reducing refractory metal oxides by metal vapor, characterized in that: include: Granulating the refractory metal oxide to form refractory metal oxide powder, wherein the powder particles are small spheres with uniform pores inside; The refractory metal oxide powder is evenly spread in the first reaction vessel with a thickness of 2 to 50 mm, wherein a plurality of through holes are evenly opened at the bottom of the first reaction vessel; Evenly laying the reducing metal in the second reaction vessel, wherein the amount of the reducing metal added is 1 to 5 times the theoretical molar amount of the reduced refractory metal oxide; The first reaction vessel is placed on the second reaction vessel and then placed into a reaction furnace, wherein an inert gas inlet is provided at one end of the reaction furnace and a condensation collector is provided at the other end of the reaction furnace; Inert gas is introduced into the reaction furnace, and the reaction furnace is heated to 650-1200° C. in an inert atmosphere, and kept warm for 1-8 hours, so that the reduced metal in the second reaction dish evaporates into metal vapor, enters the first reaction dish through the through hole at the bottom of the first reaction dish, and then enters the interior of the refractory metal oxide powder through the pores of the refractory metal oxide powder, undergoes a reduction reaction with the refractory metal oxide, and obtains a refractory metal oxide with a low oxygen content; The obtained low-oxygen-content refractory metal oxide is ground, purified by acid washing, dried, and then evenly laid in a first reaction vessel; Evenly laying the reducing metal in the second reaction vessel, wherein the amount of the reducing metal added is 1 to 5 times the theoretical molar amount of the reduced low-oxygen refractory metal oxide; The first reaction dish is placed on the second reaction dish, and then put into a reaction furnace, heated to 650-1200° C. in an inert atmosphere, and kept warm for 0.5-6 hours, the reduced metal in the second reaction dish evaporates into metal vapor, enters the first reaction dish through the through hole at the bottom of the first reaction dish, and then enters the interior of the low-oxygen-content refractory metal oxide through the pores of the low-oxygen-content refractory metal oxide, undergoes a reduction reaction with the low-oxygen-content refractory metal oxide, and obtains a refractory metal crude product; The crude refractory metal product is ground, purified by acid washing, and dried to obtain refractory metal powder.
2. The method for reducing refractory metal oxides by metal vapor according to claim 1, characterized in that: The particle size of the refractory metal oxide powder is 10 to 80 μm.
3. The method for reducing refractory metal oxides by metal vapor according to claim 1, characterized in that: The through hole formed at the bottom of the first reaction vessel has a diameter of 0.05 to 1.5 mm.
4. The method for reducing refractory metal oxides by metal vapor according to claim 1, characterized in that: The refractory metal oxide is Ta2O5, Nb2O5, TiO2 or V2O5.
5. The method for reducing refractory metal oxides by metal vapor according to claim 1, characterized in that: The reducing metal is a combination of one or more of magnesium, calcium and aluminum.
6. The method for reducing refractory metal oxides by metal vapor according to claim 1, characterized in that: The reducing metal is in the form of powder, chips or particles.
7. The method for reducing refractory metal oxides by metal vapor according to claim 1, characterized in that: The inert gas is argon.
8. The method for reducing refractory metal oxides by metal vapor according to claim 1, characterized in that: The first reaction vessel is made of nickel-based alloy, ceramic, heat-resistant steel or the same metal as the refractory metal oxide.
9. The method for reducing refractory metal oxides by metal vapor according to claim 1, characterized in that: The second reaction vessel is made of nickel-based alloy, ceramic, heat-resistant steel or the same metal as the refractory metal oxide.
10. The method for reducing refractory metal oxides by metal vapor according to claim 1, characterized in that: During the acid washing and purification process, the acid solution used is a combination of one or more of HCl, HNO3, and H2SO4.