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

Abstract

The invention provides a device and method for preparing refractory metal or low-valence oxide powder, and relates to the technical field of metallurgical processes. The device comprises a feeding transition area, a heating reaction area and a water-cooling passivation area which are sequentially arranged in a furnace tube, gates are arranged between the feeding transition area and the heating reaction area, between the heating reaction area and the water-cooling passivation area, at one end, far away from the heating reaction area, of the feeding transition area and at one end, far away from the heating reaction area, of the water-cooling passivation area; the feeding transition area, the heating reaction area and the water-cooling passivation area are respectively provided with an independent argon supply system; the heating reaction area is also provided with a vacuum system, a condensation collector and a heating furnace body; and the water cooling passivation area is provided with a water cooling device. According to the device, multiple batches of materials can be intermittently reduced, the defect that a pit furnace can only reduce one batch of materials at a time is overcome, large-scale production of refractory metal or low-valence oxide powder is achieved, the reduction efficiency is improved, and the requirement of industrial production can be met.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgical process, 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, high melting point, good electrical and thermal conductivity, and excellent corrosion resistance. Its unique physical and chemical properties make it widely used in many fields such as the electronics industry (especially tantalum capacitors), aerospace (such as supersonic aircraft and rocket engine components), chemical equipment, and medical fields (orthopedic implants and dental equipment). Tantalum capacitors, as a type of electrolytic capacitor, occupy an important position in the electronics industry with their high energy density, small size, long life, good stability and reliability. Tantalum powder is the key raw material for manufacturing 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 been industrialized. The sodium reduction of potassium fluorotantalate is the most widely used method for preparing tantalum powder in industry at home and abroad. This process uses liquid sodium as a reducing agent to reduce potassium fluorotantalate, and at the same time adds a large amount of halide salt as an additive to perform liquid stirring reduction, which can prepare tantalum powder with high specific volume. However, this method is a liquid-liquid reaction with a fast reaction speed and high heat release. Under the action of stirring, the materials in different areas are unevenly distributed, making it difficult to create the same reaction environment, and it is impossible to obtain powder with uniform particles and pores. It can only be used at a low enabling voltage and cannot meet the application requirements of high-performance tantalum capacitors.

[0004] The magnesium reduction tantalum oxide method can be divided into gaseous magnesium reduction, magnesium heat self-propagation method and liquid magnesium reduction method according to different reaction forms. US6558447B1 patent discloses a device and method for gaseous magnesium reduction, which uses different device structures to make magnesium vapor react with tantalum oxide, and the obtained tantalum powder has a large specific surface area. This method has a slow reaction speed, usually requires secondary reduction, and the magnesium vapor is difficult to control during the reaction process, and it is impossible to ensure that the magnesium vapor is in uniform contact with the material, and the requirements for the reaction device are high. The magnesium heat self-propagation method uses the heat of the reaction itself after ignition to continue the reduction, with a fast reaction speed and low energy consumption, but the reaction temperature is high, and the reaction process is not easy to control, resulting in extremely uneven distribution of tantalum powder reduction rate and particle size in time and space. CN114192791A patent uses liquid magnesium reduction method, adds a large amount of reducing agent and additives, and does not perform briquetting. After the raw materials are evenly mixed, they are directly placed in a crucible and heated to 800℃~1000℃ for reaction, and a high-reliability tantalum powder with good performance is obtained. 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. CN117840420A patent discloses a device and method for reducing liquid magnesium, which is sequentially carried out in a pit furnace: loading-heating-insulation-cooling-magnesium discharge-cooling-passivation-out of the furnace. 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 all the time. The error of manual operation has a great influence on the experimental product, and the stability of product performance is poor. Therefore, how to disclose a process that is simple in preparation method and can 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, it is difficult to achieve efficient and continuous production, and the product quality is poor.

[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 which are sequentially arranged in a furnace tube;

[0008] Gates are arranged 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, the heating reaction zone and the 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-cooling 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 device according to claim 1, comprising the following steps:

[0013] 1) Mixing the metal oxide to be reduced, the reducing agent and the additive into a heating container and placing the container into a feed transition zone, closing 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, and opening the inert gas supply system 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 the vacuum system and condensation collector are turned on to condense and collect the reducing agent that has not reacted completely;

[0015] 3) opening the gate between the heating reaction zone and the water-cooling passivation zone and moving the heating container into the water-cooling 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 Ta 2 O 5 , Nb 2 O 5 、TiO 2 、ZrO 2 or V 2 O 5 ;

[0018] The reducing agent includes Mg, Al, Ca, Y, Nd, La and CaH 2 One or more of the following;

[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 added amount of the reduced metal oxide, reducing agent and additive 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 of the present invention can be used to reduce multiple batches of materials intermittently, improving the weakness of the pit furnace that can only reduce batches one by one, realizing the large-scale production of refractory metals or low-valent oxide powders, improving the reduction efficiency, and meeting the needs of industrial production. Compared with the liquid magnesium reduction process using a pit furnace, this process uses a program setting, this intermittent reduction method, different heating containers react in different functional areas according to the same process conditions, saving manpower and reducing costs, while avoiding interference from human factors and ensuring the stability of product performance. On the basis of automatic continuity, this process can prepare products under different process conditions by changing process parameters at any time during the continuous reduction process, and the production process is more flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of an apparatus for preparing refractory metal or low-valent oxide powder;

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

[0028] Figure 3 This is a microscopic morphology of the metal 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, the heating reaction zone and the 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 also includes 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 arranged 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 device according to claim 1, comprising the following steps:

[0040] 1) Mixing the metal oxide to be reduced, the reducing agent and the additive into a heating container and placing the container into a feed transition zone, closing 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, and opening the inert gas supply system 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 the vacuum system and condensation collector are turned on to condense and collect the reducing agent that has not reacted completely;

[0042] 3) opening the gate between the heating reaction zone and the water-cooling passivation zone and moving the heating container into the water-cooling 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 Ta 2 O 5 , Nb 2 O 5 、TiO 2 、ZrO 2 or V 2 O 5 .

[0045] In the present invention, the reducing agent includes Mg, Al, Ca, Y, Nd, La and CaH 2 One or more of the .

[0046] In the present invention, the additive is one or more of metal halides, specifically MgCl 2 , KCl, NaCl, CaCl 2 NH 4 Cl、LaCl 3 and YCl 3 One or more of the .

[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 of excessive 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 in conjunction with the embodiments, but they should not be construed as limiting the protection scope 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 operation steps are as follows:

[0056] (1) First, follow Ta 2 O 5 , Mg and MgCl 2 The ingredients are prepared in a molar ratio of 1:10:6 and uniformly mixed to obtain a mixed material, and the materials are placed in a tantalum boat, and the amount of the mixed raw material added to each boat is half of the height of the boat.

[0057] Close the gate between the feed transition zone and the heating reaction zone, as well as the gate 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, and 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 to 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, and 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 950°C for metal thermal reduction reaction, stop heating after 2 hours of reaction, and start the vacuum system after the temperature naturally drops to 640°C, maintain the vacuum degree of the heating reaction zone below 10Pa, maintain 640°C for vacuum magnesium removal, and complete 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 heating reaction zone and the water-cooled passivation zone and move the tantalum boat into the water-cooled passivation zone for cooling. Rapidly cool to 35° C. in the water-cooled chamber of the water-cooled passivation zone to obtain a metal tantalum powder product.

[0060] The tantalum powder prepared in this example is Figure 2 As shown, the particle size is between 150 and 300 nm, has 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, follow Ta 2 O 5 The molar ratio of Ca and KCl is 1:12.5:5, and the ingredients are evenly mixed to obtain a mixed material, and the materials are placed in a tantalum boat, and the amount of the mixed raw material added to each boat is half of the height of the boat.

[0063] Close the gate between the feed transition zone and the heating reaction zone, as well as the gate 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, and 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 to 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, and 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 900°C for metal thermal reduction reaction, stop heating after 2 hours of reaction, and start the vacuum system after the temperature naturally drops to 700°C, maintain the vacuum degree of the heating reaction zone below 10Pa, maintain 700°C for vacuum calcium removal, and end the calcium removal 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 heating reaction zone and the water-cooled passivation zone and move the tantalum boat into the water-cooled passivation zone for cooling. Rapidly cool to 35° C. in the water-cooled chamber of the water-cooled passivation zone to obtain a metal tantalum 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, according to Nb 2 O 5 , Mg and MgCl 2 The ingredients are prepared and uniformly mixed in a molar ratio of 1:15:3 to obtain a mixed material, and the materials are placed in a niobium boat. The amount of the mixed raw material added to each boat is half of 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, preheat the heating reaction zone, and start the inert gas supply system to replace the gas in the heating reaction zone, and the inert gas is argon; when the temperature reaches 850°C, open the gate at the end of the feed transition zone away from the heating reaction zone to 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, and 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 850°C for metal thermal reduction reaction, stop heating after 8 hours of reaction, and start the vacuum system after the temperature naturally drops to 640°C, maintain the vacuum degree of the heating reaction zone below 10 Pa, maintain 640°C for vacuum magnesium removal, and end 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) Open the gate between the heating reaction zone and the water-cooled passivation zone and move the niobium boat into the water-cooled passivation zone for cooling. The niobium boat is rapidly cooled to 35° C. in the water-cooled chamber of the water-cooled passivation zone to obtain a metal niobium powder product.

[0072] This embodiment can obtain Figure 3 The nano-sized 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, follow Ta 2 O 5 The ingredients are prepared and uniformly mixed in a molar ratio of Mg to 1:20 to obtain a mixed material, and the materials are placed in a tantalum boat. The amount of the mixed raw material added to each boat is half of the height of the boat.

[0075] Close the gate between the feed transition zone and the heating reaction zone, as well as the gate 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, and 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 to 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, and 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 900°C for metal thermal reduction reaction, stop heating after 2 hours of reaction, and start the vacuum system after the temperature naturally drops to 640°C, maintain the vacuum degree of the heating reaction zone below 10Pa, maintain 640°C for vacuum magnesium removal, and complete 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 heating reaction zone and the water-cooled passivation zone and move the tantalum boat into the water-cooled passivation zone for cooling. Rapidly cool to 35° C. in the water-cooled chamber of the water-cooled passivation zone to obtain a metal tantalum powder product.

[0078] The tantalum powder prepared in this example is 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 principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A device for preparing refractory metal or low-valent oxide powder, characterized in that: It includes a feed transition zone, a heating reaction zone and a water-cooling passivation zone which are sequentially arranged in the furnace tube; Gates are arranged 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, the heating reaction zone and the 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-cooling passivation zone is provided with a water cooling device.

2. A method for preparing refractory metal or low-valent oxide powder using the device according to claim 1, characterized in that: The following steps are involved: 1) Mixing the metal oxide to be reduced, the reducing agent and the additive into a heating container and placing the container into a feed transition zone, closing 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, and opening the inert gas supply system to replace the gas in the feed transition zone; 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 the vacuum system and condensation collector are turned on to condense and collect the reducing agent that has not reacted completely; 3) opening the gate between the heating reaction zone and the water-cooling passivation zone and moving the heating container into the water-cooling passivation zone for cooling to obtain a refractory metal or low-valent oxide powder product; The feed transition zone, the heating reaction zone and the water-cooling passivation zone can operate simultaneously and continuously.

3. A method for preparing refractory metal or low-valent oxide powder according to claim 2, characterized in that: In step 1), the oxide to be reduced 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.

4. A method for preparing refractory metal or low-valent oxide powder according to claim 3, 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 added amount of the reduced metal oxide, reducing agent and additive is 0.5 to 0.75 times the height of the heating container.

5. A method for preparing refractory metal or low-valent oxide powder according to claim 4, 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.

6. A method for preparing refractory metal or low-valent oxide powder according to any one of claims 3 to 5, 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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