Device and method for preparing refractory metal or low-valent oxide powder

Abstract

The present invention provides an apparatus and method for preparing refractory metal or low-valent oxide powders, relating to the field of metallurgical process technology. The apparatus comprises a feed transition zone, a heating reaction zone, and a water-cooled passivation zone, which are sequentially arranged within a furnace tube; gates are provided between the feed transition zone and the heating reaction zone, between the heating reaction zone and the water-cooled passivation zone, and at one end of the feed transition zone away from the heating reaction zone and at one end of the water-cooled passivation zone away from the heating reaction zone; the feed transition zone, the heating reaction zone, and the water-cooled passivation zone are each provided with an independent argon gas supply system; the heating reaction zone is also provided with a vacuum system, a condensate collector, and a heating furnace body; and the water-cooled passivation zone is provided with a water cooling device. The apparatus can intermittently reduce multiple batches of material, improving the shortcoming of a pit furnace that can only reduce one batch of material at a time, enabling large-scale production of refractory metal or low-valent oxide powders, improving reduction efficiency, and meeting the needs of industrial production.

Description

Technical Field

[0001] The present invention relates to the field of metallurgical process technology, and in particular to a device and method for preparing refractory metal or low-valent oxide powder. Background Art

[0002] Tantalum is a rare metal with high density, a high melting point, good electrical and thermal conductivity, and excellent corrosion resistance. Its unique physical and chemical properties have led to its widespread use in a variety of fields, including the electronics industry (particularly tantalum capacitors), aerospace (such as supersonic aircraft and rocket engine components), chemical equipment, and the medical field (orthopedic implants and dental instruments). Tantalum capacitors, a type of electrolytic capacitor, occupy an important position in the electronics industry due to their high energy density, small size, long life, and good stability and reliability. Tantalum powder is a key raw material for the manufacture of tantalum capacitor anode materials. The performance of tantalum powder determines the performance of tantalum capacitors, and the physical and chemical properties of tantalum powder are closely related to its preparation process.

[0003] There are many methods for preparing tantalum powder, but currently only the sodium reduction of potassium fluorotantalate and magnesium reduction of tantalum oxide have achieved industrialization. The sodium reduction of potassium fluorotantalate is the most widely used tantalum powder preparation method in industry, both domestically and internationally. This process uses liquid sodium as a reducing agent to reduce potassium fluorotantalate, while adding a large amount of halide salt as an additive. This process involves liquid stirring and reduction, resulting in a high-specific-volume tantalum powder. However, this method involves a liquid-liquid reaction, resulting in a fast reaction rate and high heat release. The stirring process also results in uneven distribution of materials in different areas, making it difficult to create a uniform reaction environment. This makes it impossible to obtain a powder with uniform particles and pores, and it can only be used at low energizing voltages, failing to meet the application requirements of high-performance tantalum capacitors.

[0004] The magnesium reduction of tantalum oxide can be categorized by different reaction types, including gaseous magnesium reduction, self-propagating magnesium heat, and liquid magnesium reduction. US Patent No. 6558447B1 discloses an apparatus and method for gaseous magnesium reduction, employing a different device structure to react magnesium vapor with tantalum oxide, resulting in a tantalum powder with a large specific surface area. This method has a slow reaction rate and typically requires a secondary reduction. Furthermore, the magnesium vapor is difficult to control during the reaction, making it difficult to ensure uniform contact between the magnesium vapor and the material, placing high demands on the reaction apparatus. The self-propagating magnesium heat method utilizes the heat of the post-ignition reaction itself to maintain the reduction process, resulting in a fast reaction rate and low energy consumption. However, the reaction temperature is high, making the reaction difficult to control, and resulting in extremely uneven temporal and spatial distribution of the tantalum powder reduction rate and particle size. Patent No. 114192791A utilizes a liquid magnesium reduction method, adding a large amount of reducing agent and additives without briquetting. After the raw materials are evenly mixed, they are directly placed in a crucible and heated to 800°C to react, producing a highly reliable tantalum powder with excellent performance. This method reduces the heat released by the reaction system and the reaction rate, and has certain advantages in reaction control and powder performance regulation. Patent CN117840420A discloses a device and method for reducing liquid magnesium, which is sequentially carried out in a pit furnace: loading - heating - heat preservation - cooling - magnesium discharge - cooling - passivation - furnace discharge. The entire reduction process is long, and manual operation is required at different process nodes. The operation is cumbersome, and the experimental process needs to be supervised by someone at all times. The error of manual operation has a significant impact on the experimental product, and the stability of the product performance is poor. Therefore, how to disclose a process with a simple preparation method and the ability to continuously produce tantalum metal powder or other refractory metals and low-valent oxide powders is a problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a device and method for preparing refractory metal or low-valent oxide powder, so as to solve the problems that the existing preparation process of refractory metal powder is complicated, difficult to achieve efficient and continuous production, and has poor product quality.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a device for preparing refractory metal or low-valent oxide powder, comprising a feed transition zone, a heating reaction zone and a water-cooling passivation zone sequentially arranged in a furnace tube;

[0008] Gates are provided between the feed transition zone and the heating reaction zone, between the heating reaction zone and the water-cooling passivation zone, at one end of the feed transition zone away from the heating reaction zone, and at one end of the water-cooling passivation zone away from the heating reaction zone;

[0009] The feed transition zone, heating reaction zone and water-cooling passivation zone are all provided with independent inert gas supply systems;

[0010] The heating reaction zone is also provided with a vacuum system, a condensation collector and a heating furnace body;

[0011] The water-cooled passivation zone is provided with a water cooling device.

[0012] The present invention also provides a method for preparing refractory metal or low-valent oxide powder using the apparatus according to claim 1, comprising the following steps:

[0013] 1) The metal oxide to be reduced, the reducing agent, and the additive are mixed and placed in a heating container and then placed in a feed transition zone. The gate at the end of the feed transition zone away from the heated reaction zone and the gate between the feed transition zone and the heated reaction zone are closed, and the inert gas supply system is turned on to replace the gas in the feed transition zone.

[0014] 2) opening the gate between the feed transition zone and the heating reaction zone, moving the heating container into the heating reaction zone, closing the gate between the feed transition zone and the heating reaction zone and the gate between the heating reaction zone and the water-cooled passivation zone, and performing a metal thermal reduction reaction. After the reaction is completed, the temperature is lowered and a vacuum system and a condensation collector are opened to condense and collect the incompletely reacted reducing agent;

[0015] 3) opening the gate between the heating reaction zone and the water-cooled passivation zone and moving the heating container into the water-cooled passivation zone for cooling to obtain a refractory metal or low-valent oxide powder product;

[0016] The feed transition zone, the heating reaction zone and the water-cooling passivation zone can operate simultaneously and continuously.

[0017] Preferably, the oxide to be reduced in step 1) is Ta2O5, Nb2O5, TiO2, ZrO2 or V2O5;

[0018] The reducing agent includes one or more of Mg, Al, Ca, Y, Nd, La and CaH2;

[0019] The additive is one or more metal halides.

[0020] Preferably, in step 1), the molar ratio of the metal oxide to be reduced, the reducing agent and the additive is 1:7.5-20:0-12;

[0021] The amount of the reduced metal oxide, reducing agent and additive added is 0.5 to 0.75 times the height of the heating container.

[0022] Preferably, the temperature of the metal thermal reduction reaction in step 2) is 600-1000° C., and the time of the metal thermal reduction reaction is 1-12 hours.

[0023] Preferably, it is characterized in that the temperature of the condensation collection in step 2) is 600-750° C., and the time of the condensation collection is 3-12 hours.

[0024] The present invention has at least the following beneficial effects:

[0025] The device described in the present invention enables intermittent reduction of multiple batches of materials, overcoming the weakness of pit-type furnaces, which can only reduce materials in batches. This enables large-scale production of refractory metal or low-valent oxide powders, improves reduction efficiency, and meets the needs of industrial production. Compared with the liquid magnesium reduction process using pit-type furnaces, this process uses a program-programmed, intermittent reduction method, in which different heating containers react under the same process conditions in different functional areas, saving manpower and reducing costs. It also avoids interference from human factors and ensures the stability of product performance. Based on the automatic and continuous process, this process can prepare products under different process conditions at any time by changing process parameters during the continuous reduction process, making the production process more flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of an apparatus for preparing refractory metal or subvalent oxide powder;

[0027] Figure 2 This is a microscopic morphology of the tantalum metal powder prepared in Example 1;

[0028] Figure 3 This is a microscopic morphology of the metallic niobium powder prepared in Example 3;

[0029] Figure 4 This is a microscopic morphology of the metal tantalum powder prepared in Example 4. DETAILED DESCRIPTION

[0030] The present invention provides a device for preparing refractory metal or low-valent oxide powder, such as Figure 1 As shown, it comprises a feed transition zone (2), a heating reaction zone (3) and a water-cooling passivation zone (4) which are sequentially arranged in the furnace tube;

[0031] Gates (6) are provided between the feed transition zone and the heating reaction zone, between the heating reaction zone and the water-cooling passivation zone, at one end of the feed transition zone away from the heating reaction zone, and at one end of the water-cooling passivation zone away from the heating reaction zone;

[0032] The feed transition zone, heating reaction zone and water-cooling passivation zone are all provided with independent inert gas supply systems;

[0033] The feed transition zone is provided with a vacuum system (2-1);

[0034] The heating reaction zone is provided with a vacuum system, a condensation collector (3-1) and a heating furnace body;

[0035] The water-cooled passivation zone is provided with a vacuum system (4-1), a water cooling device (4-2), an air inlet (4-3) and an air outlet (4-4);

[0036] The device for preparing refractory metal or low-valent oxide powder further comprises a material preparation area (1) and a material discharge area (5).

[0037] The inert gas is one or more of argon, helium and neon.

[0038] The water cooling device is a water cooling cavity provided on the outer wall of the water-cooled passivation zone.

[0039] The present invention also provides a method for preparing refractory metal or low-valent oxide powder using the apparatus according to claim 1, comprising the following steps:

[0040] 1) The metal oxide to be reduced, the reducing agent, and the additive are mixed and placed in a heating container and then placed in a feed transition zone. The gate at the end of the feed transition zone away from the heated reaction zone and the gate between the feed transition zone and the heated reaction zone are closed, and the inert gas supply system is turned on to replace the gas in the feed transition zone.

[0041] 2) opening the gate between the feed transition zone and the heating reaction zone, moving the heating container into the heating reaction zone, closing the gate between the feed transition zone and the heating reaction zone and the gate between the heating reaction zone and the water-cooled passivation zone, and performing a metal thermal reduction reaction. After the reaction is completed, the temperature is lowered and a vacuum system and a condensation collector are opened to condense and collect the incompletely reacted reducing agent;

[0042] 3) opening the gate between the heating reaction zone and the water-cooled passivation zone and moving the heating container into the water-cooled passivation zone for cooling to obtain a refractory metal or low-valent oxide powder product;

[0043] The feed transition zone, the heating reaction zone and the water-cooling passivation zone can operate simultaneously and continuously.

[0044] In the present invention, the oxide to be reduced in step 1) is Ta2O5, Nb2O5, TiO2, ZrO2 or V2O5.

[0045] In the present invention, the reducing agent includes one or more of Mg, Al, Ca, Y, Nd, La and CaH2.

[0046] In the present invention, the additive is one or more metal halides, specifically one or more of MgCl2, KCl, NaCl, CaCl2, NH4Cl, LaCl3 and YCl3.

[0047] In the present invention, the material of the heating container is nickel-based alloy, tantalum or niobium.

[0048] In the present invention, the molar ratio of the metal oxide to be reduced, the reducing agent and the additive in step 1) is 1:7.5-20:0-12, preferably 1:9-18:2-10, more preferably 1:10-16:4-8, and more preferably 1:12-15:5-6.

[0049] In the present invention, the amount of the reduced metal oxide, reducing agent and additive added is 0.5 to 0.75 times the height of the heating container, preferably 0.55 to 0.7 times, and more preferably 0.6 to 0.65 times, to avoid splashing due to excessive addition of mixed materials during the reaction process.

[0050] In the present invention, the temperature of the metal thermal reduction reaction in step 2) is 600-1000°C, preferably 650-900°C, more preferably 700-850°C, and more preferably 750-800°C; the time of the metal thermal reduction reaction is 1-12h, preferably 3-10h, and more preferably 5-8h.

[0051] In the present invention, the temperature of the condensation collection in step 2) is 600-750°C, preferably 630-720°C, and more preferably 650-700°C; the time of the condensation collection is 3-12h, preferably 5-10h, and more preferably 7-9h.

[0052] In the present invention, the purpose of condensation collection is to utilize a vacuum environment and a condensation collector to separate the reducing agent that does not participate in the reaction in the product, thereby improving the purity of the product.

[0053] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0054] Example 1

[0055] by Figure 1 The device shown in the figure is used to prepare tantalum powder. The specific steps are as follows:

[0056] (1) First, Ta2O5, Mg and MgCl2 are prepared in a molar ratio of 1:10:6 and uniformly mixed to obtain a mixture, which is then placed in a tantalum boat. The amount of the mixture added to each boat is half the height of the boat.

[0057] Close the gates between the feed transition zone and the heating reaction zone, as well as the gates between the heating reaction zone and the water-cooled passivation zone, preheat the heating reaction zone in advance, and start the inert gas supply system to replace the gas in the heating reaction zone, where the inert gas is argon; after the temperature reaches 950°C, open the gate at the end of the feed transition zone away from the heating reaction zone and push the tantalum boat into the feed transition zone, close the gate at the end of the feed transition zone away from the heating reaction zone, and start the inert gas supply system to replace the gas in the feed transition zone, where the inert gas is argon.

[0058] (2) Open the gate between the feed transition zone and the heating reaction zone, move the tantalum boat loaded with the reaction raw materials into the heating reaction zone, and then close the gate between the feed transition zone and the heating reaction zone. Maintain the temperature at 950°C for metal thermal reduction reaction. After 2 hours of reaction, stop heating. After the temperature naturally drops to 640°C, start the vacuum system, maintain the vacuum degree of the heating reaction zone below 10Pa, maintain 640°C for vacuum magnesium removal, and complete the magnesium removal after 8 hours. During the reaction, open the inert gas supply system of the water-cooled passivation zone and replace the air in the water-cooled passivation zone with argon.

[0059] (3) Open the gate between the heated reaction zone and the water-cooled passivation zone and move the tantalum boat into the water-cooled passivation zone for cooling. The boat is rapidly cooled to 35° C. in the water-cooled chamber of the water-cooled passivation zone to obtain a tantalum metal powder product.

[0060] The tantalum powder prepared in this embodiment is as follows Figure 2 As shown, the particle size is between 150 and 300 nm, with a good pore structure, an oxygen content of less than 6000 ppm, and an impurity magnesium content of less than 15 ppm, which can meet the needs of tantalum powder for capacitors.

[0061] Example 2

[0062] (1) First, Ta2O5, Ca and KCl are prepared in a molar ratio of 1:12.5:5 and uniformly mixed to obtain a mixture, which is then placed in a tantalum boat. The amount of the mixture added to each boat is half the height of the boat.

[0063] Close the gates between the feed transition zone and the heating reaction zone, as well as the gates between the heating reaction zone and the water-cooled passivation zone, preheat the heating reaction zone in advance, and start the inert gas supply system to replace the gas in the heating reaction zone, where the inert gas is argon; after the temperature reaches 900°C, open the gate at the end of the feed transition zone away from the heating reaction zone and push the tantalum boat into the feed transition zone, close the gate at the end of the feed transition zone away from the heating reaction zone, and start the inert gas supply system to replace the gas in the feed transition zone, where the inert gas is argon.

[0064] (2) Open the gate between the feed transition zone and the heating reaction zone, move the tantalum boat loaded with the reaction raw materials into the heating reaction zone, and then close the gate between the feed transition zone and the heating reaction zone. Maintain the metal thermal reduction reaction at 900°C. After 2 hours of reaction, stop heating. After the temperature naturally drops to 700°C, start the vacuum system, maintain the vacuum degree of the heating reaction zone below 10Pa, maintain 700°C for vacuum decalcification, and complete the decalcification after 6 hours. During the reaction, open the inert gas supply system of the water-cooled passivation zone and replace the air in the water-cooled passivation zone with argon.

[0065] (3) Open the gate between the heated reaction zone and the water-cooled passivation zone and move the tantalum boat into the water-cooled passivation zone for cooling. The boat is rapidly cooled to 35° C. in the water-cooled chamber of the water-cooled passivation zone to obtain a tantalum metal powder product.

[0066] The tantalum powder particles prepared in this embodiment are well sintered to each other to form a good pore structure. The particle size of the tantalum powder is between 200 and 300 nm, and the purity is 99.98%. The impurity calcium content is less than 20 ppm, which can meet the needs of tantalum powder for high energy density capacitors.

[0067] Example 3

[0068] (1) First, Nb2O5, Mg, and MgCl2 are prepared in a molar ratio of 1:15:3 and uniformly mixed to obtain a mixture, which is then placed in a niobium boat. The amount of the mixture added to each boat is half the height of the boat.

[0069] Close the gates between the feed transition zone and the heating reaction zone, as well as the gates between the heating reaction zone and the water-cooled passivation zone, pre-prime the heating reaction zone, and start the inert gas supply system to replace the gas in the heating reaction zone. The inert gas is argon. After the temperature reaches 850°C, open the gate at the end of the feed transition zone away from the heating reaction zone and push the niobium boat into the feed transition zone. Close the gate at the end of the feed transition zone away from the heating reaction zone and start the inert gas supply system to replace the gas in the feed transition zone. The inert gas is argon.

[0070] (2) Open the gate between the feed transition zone and the heating reaction zone, move the niobium boat loaded with the reaction raw materials into the heating reaction zone, and then close the gate between the feed transition zone and the heating reaction zone. Maintain the temperature at 850°C for metallothermic reduction. After 8 hours of reaction, stop heating. After the temperature naturally drops to 640°C, start the vacuum system, maintain the vacuum degree of the heating reaction zone below 10 Pa, maintain 640°C for vacuum magnesium removal, and complete the magnesium removal after 12 hours. During the reaction, open the inert gas supply system of the water-cooled passivation zone and replace the air in the water-cooled passivation zone with argon.

[0071] (3) The gate between the heating reaction zone and the water-cooled passivation zone is opened and the niobium boat is moved into the water-cooled passivation zone for cooling. The niobium boat is rapidly cooled to 35° C. under the action of the water-cooled chamber of the water-cooled passivation zone to obtain a metallic niobium powder product.

[0072] This embodiment can obtain Figure 3 The nano-scale niobium powder shown has a particle size between 200 and 400 nm, and the niobium powder particles are well sintered to form a uniform pore structure.

[0073] Example 4

[0074] (1) First, Ta2O5 and Mg are prepared in a molar ratio of 1:20 and uniformly mixed to obtain a mixture, which is then placed in a tantalum boat. The amount of the mixture added to each boat is half the height of the boat.

[0075] Close the gates between the feed transition zone and the heating reaction zone, as well as the gates between the heating reaction zone and the water-cooled passivation zone, preheat the heating reaction zone in advance, and start the inert gas supply system to replace the gas in the heating reaction zone, where the inert gas is argon; after the temperature reaches 900°C, open the gate at the end of the feed transition zone away from the heating reaction zone and push the tantalum boat into the feed transition zone, close the gate at the end of the feed transition zone away from the heating reaction zone, and start the inert gas supply system to replace the gas in the feed transition zone, where the inert gas is argon.

[0076] (2) Open the gate between the feed transition zone and the heating reaction zone, move the tantalum boat loaded with the reaction raw materials into the heating reaction zone, and then close the gate between the feed transition zone and the heating reaction zone. Maintain the metal thermal reduction reaction at 900°C. After 2 hours of reaction, stop heating. After the temperature naturally drops to 640°C, start the vacuum system, maintain the vacuum degree of the heating reaction zone below 10Pa, maintain 640°C for vacuum magnesium removal, and complete the magnesium removal after 12 hours. During the reaction, open the inert gas supply system of the water-cooled passivation zone and replace the air in the water-cooled passivation zone with argon.

[0077] (3) Open the gate between the heated reaction zone and the water-cooled passivation zone and move the tantalum boat into the water-cooled passivation zone for cooling. The boat is rapidly cooled to 35° C. in the water-cooled chamber of the water-cooled passivation zone to obtain a tantalum metal powder product.

[0078] The tantalum powder prepared in this embodiment is as follows Figure 4 As shown, the particles are uniform, thick sintering necks are formed between the particles, the sintering strength is high, the particle size is between 150 and 200 nm, and the oxygen content of the tantalum powder is less than 4000 ppm, which can meet the needs of tantalum powder for capacitors.

[0079] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing refractory metal or subvalent oxide powder using an apparatus for preparing refractory metal or subvalent oxide powder, characterized in that: The following steps are involved: 1) The metal oxide to be reduced, the reducing agent and the additive are mixed and placed in a heating container and then placed in a feed transition zone. The gate at the end of the feed transition zone away from the heating reaction zone and the gate between the feed transition zone and the heating reaction zone are closed, and the inert gas supply system is turned on to replace the gas in the feed transition zone. 2) Open the gate between the feed transition zone and the heating reaction zone, move the heating container into the heating reaction zone, close the gate between the feed transition zone and the heating reaction zone, and the gate between the heating reaction zone and the water-cooled passivation zone, and conduct a metal thermal reduction reaction. After the reaction is completed, cool down and start the vacuum system and condensation collector to condense and collect the unreacted reducing agent; 3) Open the gate between the heating reaction zone and the water-cooled passivation zone and move the heating container into the water-cooled passivation zone for cooling to obtain a refractory metal or low-valent oxide powder product; The feed transition zone, heating reaction zone and water-cooling passivation zone can operate simultaneously and continuously; The device for preparing refractory metal or low-valent oxide powder comprises a feed transition zone, a heating reaction zone and a water-cooling passivation zone sequentially arranged in a furnace tube; Gates are provided between the feed transition zone and the heating reaction zone, between the heating reaction zone and the water-cooling passivation zone, at one end of the feed transition zone away from the heating reaction zone, and at one end of the water-cooling passivation zone away from the heating reaction zone; The feed transition zone, heating reaction zone and water-cooling passivation zone are all provided with independent inert gas supply systems; The heating reaction zone is also provided with a vacuum system, a condensation collector and a heating furnace body; The water-cooled passivation zone is provided with a water cooling device.

2. The method for preparing refractory metal or subvalent oxide powder according to claim 1, characterized in that: The oxide to be reduced in step 1) is Ta2O5, Nb2O5, TiO2, ZrO2 or V2O5; The reducing agent includes one or more of Mg, Al, Ca, Y, Nd, La and CaH2; The additive is one or more metal halides.

3. The method for preparing refractory metal or subvalent oxide powder according to claim 2, characterized in that: In step 1), the molar ratio of the metal oxide to be reduced, the reducing agent, and the additive is 1:7.5-20:0-12; The amount of the reduced metal oxide, reducing agent and additive added is 0.5 to 0.75 times the height of the heating container.

4. The method for preparing refractory metal or subvalent oxide powder according to claim 3, characterized in that: The temperature of the metal thermal reduction reaction in step 2) is 600-1000° C., and the time of the metal thermal reduction reaction is 1-12 hours.

5. The method for preparing refractory metal or subvalent oxide powder according to any one of claims 2 to 4, characterized in that: The temperature of the condensation collection in step 2) is 600-750° C., and the time of the condensation collection is 3-12 hours.

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