Device and method for preparing refractory metal and low-valence oxide through metal thermal reduction

Abstract

The invention belongs to the technical field of metal smelting, and provides a device and method for preparing refractory metal and low-valence oxide through metal thermal reduction. Comprising furnace tubes, a reaction container, a heating device and a driving device, the reaction container is arranged in the furnace tube; the heating device is arranged on the outer surface of the furnace tube; and the driving device is used for driving the reaction container to move in the furnace tube. By means of the device, automatic continuous production of the refractory metal and the low-valence oxide can be achieved, the reduction efficiency is improved, the cost is reduced, interference of human factors can be avoided, the consistency of the refractory metal and the low-valence oxide product is guaranteed, large-scale production of the refractory metal and the low-valence oxide can be achieved, and the requirement for industrial production is met.

Description

Technical Field

[0001] The present invention relates to the technical field of metal smelting, and in particular to a device and method for preparing refractory metals and low-valent oxides by metal thermal reduction. Background Art

[0002] In recent years, with the vigorous development of the new generation of information technology industry (such as integrated circuits, information communications, etc.), new energy vehicles, intelligent manufacturing, and aerospace, the demand for high energy density tantalum capacitors has become increasingly urgent. However, this demand is no longer limited to the pursuit of higher specific capacitance, but pays more attention to the improvement of the energy density of tantalum capacitors. To achieve the high energy density of tantalum capacitors, the key lies in having high specific capacitance and high breakdown voltage. The key to preparing tantalum capacitors with high specific capacitance and high breakdown voltage lies in the physical and chemical properties of the raw material tantalum powder. The physical and chemical properties of tantalum powder are closely related to its preparation process, and the preparation process will directly affect the performance of the final product.

[0003] There are many methods for preparing tantalum powder. Currently, only the sodium reduction potassium fluorotantalate method and the magnesium reduction tantalum oxide method have achieved industrialization. Among them, the sodium reduction potassium fluorotantalate process is a liquid-liquid reaction system. After adding potassium fluorotantalate and sodium, the raw materials are distributed inconsistently in different regions during the stirring process. The low-concentration area leads to the production of fine particles. The high-concentration area releases a large amount of heat, and the local heat is concentrated. The tantalum powder is more likely to grow, and it is impossible to obtain a powder with uniform particles and pores. The magnesium reduction tantalum oxide process can be divided into gaseous magnesium reduction, magnesium thermal self-propagation method and liquid magnesium reduction according to different reaction forms. The gaseous magnesium reduction process is a gas-solid reaction system. Magnesium vapor reacts with tantalum oxide particles through diffusion. The reaction speed is slow, the energy consumption is high, and it is difficult to control the good contact between magnesium vapor and raw materials. US6849104B2 and US6558447B1 patents disclose a gaseous magnesium reduction device and method. This method uses magnesium vapor generated by high temperature to reduce tantalum oxide to obtain tantalum powder with a high specific surface area, but the magnesium vapor is difficult to control during the reaction process, the equipment is complex, and the requirements for the device are high. The self-propagating magnesium thermal process has a high reaction temperature, a fast reaction speed, and poor controllability. The liquid magnesium reduction method performs a liquid-solid reaction at a relatively low temperature, has a moderate reaction speed, and is highly controllable, but the equipment operation is cumbersome, the human factor has a greater impact, the reproducibility and consistency of the tantalum powder results are poor, and the production efficiency is low and the cost is high. For example, in the Chinese invention patent CN117840420A, a device and method for liquid magnesium reduction are disclosed. The entire reduction process is long and the operation is cumbersome. It can only be processed one furnace at a time, requiring more manpower, and cannot be produced continuously, and product consistency is difficult to ensure.

[0004] In summary, there is an urgent need to provide a tantalum powder preparation device and method with a simple reduction process, capable of continuous production, capable of ensuring product consistency, and having high production efficiency and low cost. Summary of the invention

[0005] In view of this, the present invention provides an apparatus and method for preparing refractory metals and low-valent oxides by metal thermal reduction, so as to solve the problems that the existing preparation process of refractory metals and low-valent oxides is complicated, continuous production cannot be achieved, product consistency cannot be guaranteed, production efficiency is low, and cost is high.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The present invention provides a device for preparing refractory metals and low-valent oxides by metal thermal reduction, comprising a furnace tube, a reaction vessel, a heating device and a driving device; the reaction vessel is arranged inside the furnace tube; the heating device is arranged on the outer surface of the furnace tube; the driving device is used to drive the reaction vessel to move inside the furnace tube.

[0008] Preferably, the furnace tube is a closed furnace tube, comprising a furnace tube body, a first furnace door, a second furnace door, a first air hole and a second air hole; the first furnace door and the second furnace door are respectively installed at both ends of the furnace tube body, the reaction container enters the interior of the furnace tube body through the first furnace door, and the reaction container leaves the interior of the furnace tube body through the second furnace door; the first air hole and the second air hole are respectively opened on the side surface of the furnace tube body.

[0009] Preferably, a plurality of reaction containers are provided, and the plurality of reaction containers are slidably connected to the interior of the furnace tube body in sequence.

[0010] Preferably, the heating device is a cylindrical heating body, and the cylindrical heating body is arranged around the outer surface of the furnace tube body; the inner diameter of the cylindrical heating body is larger than the outer diameter of the furnace tube body.

[0011] Preferably, the device for preparing refractory metals and low-valent oxides by metal thermal reduction also includes an inert gas generating device, which is connected to the first pore and the second pore and is used to introduce inert gas into the interior of the furnace tube body.

[0012] The present invention also provides a method for preparing refractory metals and low-valent oxides by using the above device, comprising the following steps:

[0013] Refractory metal oxides, reducing agents and additives are mixed to obtain a mixture, which is added to a reaction vessel. After the heating device heats the furnace tube and the inert gas generating device introduces inert gas into the furnace tube, the driving device pushes the reaction vessel from the furnace tube inlet to the outlet for a reduction reaction to obtain refractory metals or low-valent oxides.

[0014] Preferably, the refractory metal oxide is tantalum oxide or niobium oxide; and the low-valent oxide is niobium monoxide or niobium dioxide having an oxygen content of 14.8-15.2%.

[0015] Preferably, when the refractory metal oxide is tantalum oxide, the molar ratio of the tantalum oxide, the reducing agent and the additive is 1:7.5-15:1-12; when the refractory metal oxide is niobium oxide, the molar ratio of the niobium oxide, the reducing agent and the additive is 1:10-20:1-12.

[0016] Preferably, the reduction reaction temperature is 600-1000° C., the time is 2-12 hours, and the inert atmosphere is argon atmosphere or helium atmosphere.

[0017] Preferably, the reducing agent includes one or more of Mg, Ca, Al, MgH2, CaH2 and rare earth; the additive includes one or more of KCl, MgCl2, CaCl2 and NaCl.

[0018] Preferably, the height of adding the mixed material is 50-75% of the height of the reaction container.

[0019] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0020] The device for preparing refractory metals and low-valent oxides by metal thermal reduction of the present invention is simple, can realize automatic and continuous production of preparing refractory metals and low-valent oxides, and improve reduction efficiency. At the same time, the device can change the type and proportion of added materials, heating temperature and reaction vessel rate in real time through program settings, so that the process of preparing refractory metals and low-valent oxides by metal thermal reduction is more flexible, and can also avoid interference from human factors, ensure the stability of refractory metals and low-valent oxides, and further ensure the consistency of products.

[0021] The existing device for preparing refractory metals and low-valent oxides is a pit furnace, which has only one port for feeding and discharging, and has no way to carry out continuous production. Refractory metals and low-valent oxides can only be prepared by reduction in each furnace, and the device requires manual operation, which will have a great impact on the performance of products from different furnaces. The device described in the present invention can achieve continuous production, and the process of preparing refractory metals and low-valent oxides using the device described in the present invention can not only improve the reduction efficiency and realize the continuous reduction process, but also save manpower, reduce costs, and ensure the consistency of refractory metals and low-valent oxide products, and is more suitable for large-scale preparation of refractory metals and low-valent oxides to meet the needs of industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0023] Figure 1 A schematic diagram of a device for preparing refractory metals and low-valent oxides by metal thermal reduction according to the present invention;

[0024] Figure 2 This is a morphology diagram of the refractory metal tantalum powder prepared in Example 1; wherein: 1. furnace tube body; 2. reaction vessel; 3. cylindrical heating body; 4. driving device; 11. first furnace door; 12. second furnace door; 13. first pore; 14. second pore. DETAILED DESCRIPTION

[0025] The present invention provides a device for preparing refractory metals and low-valent oxides by metal thermal reduction, comprising a furnace tube, a reaction vessel 2, a heating device and a driving device 4; the reaction vessel 2 is arranged inside the furnace tube; the heating device is arranged on the outer surface of the furnace tube; the driving device 4 is used to drive the reaction vessel 2 to move inside the furnace tube.

[0026] In the present invention, the furnace tube is a closed furnace tube, including a furnace tube body 1, a first furnace door 11, a second furnace door 12, a first air hole 13 and a second air hole 14; the first furnace door 11 and the second furnace door 12 are respectively installed at both ends of the furnace tube body 1, the reaction container 2 enters the interior of the furnace tube body 1 through the first furnace door 11, and the reaction container 2 leaves the interior of the furnace tube body 1 through the second furnace door 12; the first air hole 13 and the second air hole 14 are respectively opened on the side surface of the furnace tube body 1.

[0027] like Figure 1 As shown, in the present invention, the first air hole 13 is opened on the side surface of the furnace tube body 1 close to the first furnace door 11; the second air hole 14 is opened on the side surface of the furnace tube body 1 close to the second furnace door 12.

[0028] In the present invention, a plurality of reaction containers 2 are provided, and the plurality of reaction containers 2 are slidably connected to the inside of the furnace tube body 1 in sequence, and the height and width of the reaction containers 2 are smaller than the inner diameter of the furnace tube body 1 .

[0029] In the present invention, the heating device is a cylindrical heating body 3, which is arranged around the outer surface of the furnace tube body 1; the inner diameter of the cylindrical heating body 3 is larger than the outer diameter of the furnace tube body 1, and the length of the cylindrical heating body 3 is preferably smaller than the length of the furnace tube body 1.

[0030] In the present invention, the device for preparing refractory metals and low-valent oxides by metal thermal reduction also includes an inert gas generating device, which is connected to the first air hole 13 and the second air hole 14 and is used to introduce inert gas into the interior of the furnace tube body 1.

[0031] The present invention also provides a method for preparing refractory metals and low-valent oxides by using the above device, comprising the following steps:

[0032] Refractory metal oxides, reducing agents and additives are mixed to obtain a mixture, which is added to a reaction vessel 2. After the heating device heats the furnace tube and the inert gas generating device introduces inert gas into the furnace tube, the driving device 4 pushes the reaction vessel 2 from the furnace tube inlet to the outlet for a reduction reaction to obtain refractory metals or low-valent oxides.

[0033] In the present invention, the refractory metal oxide is tantalum oxide or niobium oxide; the low-valent oxide is niobium monoxide or niobium dioxide with an oxygen content of 14.8-15.2%.

[0034] In the present invention, the oxygen content of the niobium monoxide or niobium dioxide is preferably 14.9-15.1%, more preferably 15.0%.

[0035] In the present invention, when the refractory metal oxide is tantalum oxide, the molar ratio of the tantalum oxide, the reducing agent and the additive is 1:7.5-15:1-12, preferably 1:8-13.5:2-10, and more preferably 1:9-10:3-5; when the refractory metal oxide is niobium oxide, the molar ratio of the niobium oxide, the reducing agent and the additive is 1:10-20:1-12, preferably 1:12-18:2-10, and more preferably 1:13-15:5-6.

[0036] In the present invention, the temperature of the reduction reaction is 600-1000°C, preferably 700-950°C, further preferably 750-900°C, and more preferably 800°C; the time of the reduction reaction is 2-12h, preferably 3-10h, further preferably 5-8h, and more preferably 6h; the inert atmosphere of the reduction reaction is argon atmosphere or helium atmosphere, preferably argon atmosphere.

[0037] In the present invention, the inert atmosphere of the reduction reaction may also be replaced by a hydrogen atmosphere.

[0038] In the present invention, the reducing agent includes one or more of Mg, Ca, Al, MgH2, CaH2 and rare earth, preferably Mg or MgH2; the additive includes one or more of KCl, MgCl2, CaCl2 and NaCl.

[0039] In the present invention, the height of adding the mixed material is 50-75% of the height of the reaction container, preferably 55-70%, more preferably 60%, so as to avoid splashing of the mixed material due to excessive addition during the reaction process.

[0040] 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.

[0041] Example 1 Preparation of Refractory Metal Tantalum Powder

[0042] Firstly, tantalum oxide Ta2O5, Mg reducing agent and KCl additive are mixed in a molar ratio of 1:7.5:3 to obtain a mixture, and then the mixture is put into a reaction container, the amount of the mixture added to each reaction container is 50% of the height of the reaction container, and after the heating device heats the furnace tube to 800°C and the inert gas generating device introduces argon gas into the furnace tube so that the interior of the furnace tube is filled with argon gas atmosphere, the driving device pushes the reaction container once every 30 minutes to move the reaction container from the first furnace door to the second furnace door for reduction reaction, the reduction reaction time is 6 hours, and refractory metal tantalum powder is obtained.

[0043] This embodiment uses Figure 1 The device shown performs metal thermal reduction to prepare refractory metal tantalum powder. The entire reduction process is carried out automatically and continuously, which improves production efficiency and avoids interference from human factors, ensuring the stability of the tantalum powder performance in each reaction container.

[0044] The tantalum powder obtained in this example was subjected to a morphology characterization experiment, and the results are as follows: Figure 2 As shown, from Figure 2 It can be seen that the particle size of the tantalum powder particles is between 150 and 300 nm, the particles are relatively uniform, and there are fewer small particles attached to the surface. In addition, the oxygen content in the tantalum powder obtained in this embodiment is between 7000 and 8500 ppm, and the difference in oxygen content is small, which shows that the tantalum powder prepared by the device of the present invention has stable performance.

[0045] Example 2 Preparation of refractory metal niobium powder

[0046] Firstly, niobium oxide Nb2O5, Mg reducing agent and KCl additive are mixed in a molar ratio of 1:15:5 to obtain a mixture, and then the mixture is put into a reaction container, the amount of the mixture added to each reaction container is 50% of the height of the reaction container, and after the heating device heats the furnace tube to 1000°C and the inert gas generating device introduces argon gas into the furnace tube so that the interior of the furnace tube is filled with argon gas atmosphere, the driving device pushes the reaction container once every 120 minutes to move the reaction container from the first furnace door to the second furnace door for reduction reaction, the reduction reaction time is 8 hours, and refractory metal niobium powder is obtained.

[0047] This embodiment uses Figure 1 The device shown performs metal thermal reduction to prepare refractory metal niobium powder, and the niobium powder obtained in different reaction vessels is pickled to obtain pure niobium powder. The morphology and impurity content of the obtained pure niobium powder are then characterized. It is found that the niobium powder obtained in different reaction vessels has similar morphology, close particle size distribution, and the difference in oxygen content in the impurity content is less than 5%, that is, the product prepared by the device described in the present invention has stable performance.

[0048] Example 3 Preparation of Refractory Metal Tantalum Powder

[0049] Tantalum oxide Ta2O5, Mg reducing agent and KCl additive are mixed in a molar ratio of 1:15:6 to obtain a mixture, and then the mixture is put into a reaction container. The amount of the mixture added to each reaction container is 50% of the height of the reaction container. After the heating device heats the furnace tube to 950°C and the inert gas generating device introduces argon gas into the furnace tube so that the interior of the furnace tube is filled with argon gas atmosphere, the driving device pushes the reaction container once every 60 minutes to move the reaction container from the first furnace door to the second furnace door for reduction reaction. The reduction reaction time is 2 hours to obtain refractory metal tantalum powder.

[0050] This embodiment uses Figure 1 The device shown performs metal thermal reduction to prepare refractory metal tantalum powder. The entire reduction process is carried out automatically and continuously, realizing large-scale continuous production of tantalum powder. At the same time, the tantalum powder particles obtained in different reaction vessels are uniform, forming a good sintering structure. The oxygen content in the tantalum powder is between 4000 and 5500 ppm, and the magnesium content is less than 30 ppm, which can meet the production requirements for preparing high-voltage tantalum capacitors.

[0051] 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 metals and low-valent oxides by metal thermal reduction, characterized in that: It includes a furnace tube, a reaction vessel, a heating device and a driving device; The reaction container is arranged inside the furnace tube; The heating device is arranged on the outer surface of the furnace tube; The driving device is used for driving the reaction container to move in the furnace tube.

2. The device for preparing refractory metals and low-valent oxides by metal thermal reduction according to claim 1, characterized in that: The furnace tube is a closed furnace tube, comprising a furnace tube body, a first furnace door, a second furnace door, a first air hole and a second air hole; The first furnace door and the second furnace door are respectively installed at two ends of the furnace tube body, the reaction container enters the interior of the furnace tube body through the first furnace door, and the reaction container leaves the interior of the furnace tube body through the second furnace door; The first air hole and the second air hole are respectively opened on the side surface of the furnace tube body.

3. The device for preparing refractory metals and low-valent oxides by metal thermal reduction according to claim 2, characterized in that: A plurality of reaction containers are provided, and the plurality of reaction containers are slidably connected to the interior of the furnace tube body in sequence.

4. The device for preparing refractory metals and low-valent oxides by metal thermal reduction according to any one of claims 1 to 3, characterized in that: The heating device is a cylindrical heating body, and the cylindrical heating body is arranged around the outer surface of the furnace tube body; The inner diameter of the cylindrical heating body is greater than the outer diameter of the furnace tube body.

5. The device for preparing refractory metals and low-valent oxides by metal thermal reduction according to claim 4, characterized in that: The furnace tube body further comprises an inert gas generating device, which is connected to the first gas hole and the second gas hole and is used for introducing inert gas into the interior of the furnace tube body.

6. A method for preparing refractory metals and low-valent oxides using the device according to any one of claims 1 to 5, characterized in that: The steps include: Refractory metal oxides, reducing agents and additives are mixed to obtain a mixture, which is added to a reaction vessel. After the heating device heats the furnace tube and the inert gas generating device introduces inert gas into the furnace tube, the driving device pushes the reaction vessel from the furnace tube inlet to the outlet for a reduction reaction to obtain refractory metals or low-valent oxides.

7. A method for preparing refractory metals and low-valent oxides according to claim 6, characterized in that: The refractory metal oxide is tantalum oxide or niobium oxide; The low-valent oxide is niobium monoxide or niobium dioxide with an oxygen content of 14.8-15.2%.

8. A method for preparing refractory metals and low-valent oxides according to claim 7, characterized in that: When the refractory metal oxide is tantalum oxide, the molar ratio of the tantalum oxide, the reducing agent and the additive is 1:7.5-15:1-12; When the refractory metal oxide is niobium oxide, the molar ratio of the niobium oxide, the reducing agent and the additive is 1:10-20:1-12; The temperature of the reduction reaction is 600-1000° C., the time is 2-12 hours, and the inert atmosphere is an argon atmosphere or a helium atmosphere.

9. A method for preparing refractory metals and low-valent oxides according to claim 8, characterized in that: The reducing agent includes one or more of Mg, Ca, Al, MgH2, CaH2 and rare earth; The additive includes one or more of KCl, MgCl2, CaCl2, and NaCl.

10. The method for preparing refractory metals and subvalent oxides according to any one of claims 6 to 9, characterized in that: The adding height of the mixed material is 50-75% of the height of the reaction container.

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