Apparatus and method for preparing metal powder by constant concentration gas-solid reduction
By designing an open gas box and gas inlet pipe inside the furnace tube, the problems of uneven reaction rate and impurity retention caused by hydrogen concentration gradient were solved, achieving efficient and uniform reduction of metal powder and high-purity preparation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHENGZHOU UNIV
- Filing Date
- 2026-04-29
- Publication Date
- 2026-06-12
AI Technical Summary
The traditional one-way hydrogen supply method results in a decrease in hydrogen concentration along the furnace tube direction, which leads to a decrease in reaction rate, uneven powder particle size, and difficulty in removing impurities, thus affecting the reduction efficiency and purity of metal powder.
The design employs an open gas box and inlet pipe inside a closed furnace tube. Hydrogen gas is evenly distributed and flows in a direction through the open gas box, while the generated byproducts and impurities are quickly discharged through the exhaust pipe, ensuring the uniformity and purity of the reaction atmosphere.
This method achieves uniform distribution of hydrogen within the furnace tube, improves reaction rate and product purity, ensures uniform particle size and efficient impurity removal, and enhances the quality and yield of metal powder.
Smart Images
Figure CN122191971A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of metal smelting technology, and in particular to an apparatus and method for preparing metal powder by constant concentration gas-solid reduction. Background Technology
[0002] The reduction of refractory metal oxides with hydrogen to prepare metal powders (such as Mo, W, Co, Cu, Fe, La, etc.) is a common process in the metallurgical field. Currently, both domestically and internationally, a boat-shaped crucible is commonly used to hold the material in a horizontal reduction furnace. The material undergoes a gas-solid reduction reaction with hydrogen by pushing the boat. In this traditional process, hydrogen is generally introduced from the furnace tail and flows along the furnace tubes towards the furnace head, contacting and reacting with the material moving in the opposite direction. The generated water vapor and impurities are carried away from the furnace head by excess hydrogen. However, this unidirectional gas distribution and flow method has the following significant problems: (1) The hydrogen concentration decreases along the process and the reaction rate gradually decreases: As hydrogen flows from the tail of the furnace to the head of the furnace, it continuously participates in the reaction and generates water vapor, so its effective concentration gradually decreases, while the partial pressure of water vapor continuously increases, which weakens the reducing power of the reaction atmosphere in which the subsequent materials are located, and the reaction efficiency decreases accordingly.
[0003] (2) Water vapor participates in the reaction again, resulting in uneven particle size of powder: As the partial pressure of water vapor gradually increases along the furnace tube, the reduced metal particles may undergo repeated oxidation-reduction processes, causing abnormal growth of metal grains, which ultimately results in a wider range of powder particle size distribution and poor particle size uniformity.
[0004] (3) Impurities are difficult to remove effectively, affecting the purity of powder: During the reaction, volatile impurities such as potassium and sodium precipitated move with the airflow to the low-temperature feed end and condense and deposit in this area, and then adhere to the surface of the material again, resulting in impurities that cannot be completely removed, reducing the purity of metal powder.
[0005] In summary, the traditional one-way hydrogen supply method results in a significant gradient between the hydrogen concentration and the gas phase composition inside the furnace tube, which in turn causes problems such as uneven reaction rate, uncontrolled powder particle size distribution, and impurity retention, severely restricting the reduction efficiency of metal powder and product quality.
[0006] Therefore, there is an urgent need to provide an apparatus and method for preparing metal powder by gas-solid reduction that can maintain a uniform and stable reducing atmosphere, effectively separate and remove reaction byproducts, thereby improving reaction efficiency and powder quality. Summary of the Invention
[0007] In view of this, the present invention provides an apparatus and method for preparing metal powder by constant concentration gas-solid reduction, in order to solve the problems in the prior art that the hydrogen concentration and water vapor partial pressure are gradients along the furnace tube direction, resulting in uneven reaction efficiency, wide product particle size distribution and difficulty in effectively removing impurities.
[0008] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides an apparatus for preparing metal powder by constant concentration gas-solid reduction, comprising a boat pushing mechanism, a furnace body, a water cooling jacket, and a boat unloading mechanism connected in sequence. The furnace body includes furnace tubes, an open gas box, a material boat, an air inlet pipe, and a heating device; The boat-pushing mechanism is connected to the furnace body through one end of the furnace tube and is used to push the material boat into the interior of the furnace tube; the water-cooling jacket is connected to the furnace body through the other end of the furnace tube. The furnace tube is a closed furnace tube, including the furnace tube body, the first furnace door, the second furnace door, and the exhaust port; The first furnace door and the second furnace door are respectively installed at both ends of the furnace tube body. The material boat enters the interior of the furnace tube body through the first furnace door and leaves the furnace tube body through the second furnace door. The exhaust port is located on the side surface of the furnace tube body near the first furnace door; The open gas box is provided in several parts, and the open gas box is evenly arranged on the upper surface inside the furnace tube body, with the opening of the open gas box facing downward. The material boats are provided in a plurality of manner, and the plurality of material boats are slidably connected in sequence to the lower surface inside the furnace tube body, with the openings of the material boats facing upwards; The gas inlet pipe passes through the first furnace door and the second furnace door and is installed inside the several open gas boxes for introducing hydrogen into the several open gas boxes; The heating device is disposed on the outer surface of the furnace tube body.
[0009] Preferably, the width of the open gas box is equal to the width of the material boat, and the distance between both ends of the open gas box in the width direction and the inner wall of the furnace tube body in the width direction is 20~30 mm; the depth of the open gas box is ≥60 mm; the distance between the open gas box and the material boat in the depth direction is 30~40 mm; and the length of the open gas box and the material boat are independent and are 200~400 mm.
[0010] Preferably, the surface of the air inlet pipe is provided with a plurality of air outlet holes, and each air outlet hole is located inside the open gas box for introducing hydrogen gas into the interior of the open gas box.
[0011] Preferably, the heating device includes a plurality of heating elements, which are uniformly arranged on the outer surface of the furnace tube body.
[0012] Preferably, it also includes an exhaust pipe, which is connected to the furnace tube body through the exhaust port.
[0013] Preferably, the interior of the furnace tube body is sequentially provided with a preheating temperature zone, a low temperature zone, a transition temperature zone, and a high temperature zone from the first furnace door to the second furnace door; the length of the preheating temperature zone is 1~1.6 m, the length of the low temperature zone is 1~1.6 m, the length of the transition temperature zone is 1~1.6 m, and the length of the high temperature zone is 3.6~6 m; the length of the water cooling jacket is 1~2 m.
[0014] The present invention also provides a method for preparing metal powder using the above-described apparatus with constant concentration gas-solid reduction, comprising the following steps: Metal oxides are loaded into a material boat. After the heating device heats the furnace tube and hydrogen is introduced into the open gas box through the gas inlet pipe, the boat pushing mechanism pushes the material boat from the first furnace door of the furnace tube to the preheating temperature zone, low temperature zone, transition temperature zone and high temperature zone of the furnace tube in sequence, and performs preheating, first-stage reduction reaction, heating and second-stage reduction reaction accordingly. Then the material boat is pushed from the second furnace door of the furnace tube to the water cooling jacket for cooling. Finally, the material is discharged by the boat discharge mechanism to obtain metal powder. At the same time, hydrogen carrying water vapor and impurity elements is discharged from the furnace tube through the exhaust pipe.
[0015] Preferably, the metal oxide is molybdenum trioxide, tungsten trioxide, iron oxide, copper oxide, or ammonium perrhenate.
[0016] Preferably, the thickness of the metal oxide filling is 60-100% of the depth of the boat.
[0017] Preferably, the hydrogen inlet pressure is 0.1~0.2 MPa; the temperature of the preheating zone is 400~650℃; the temperature of the low temperature zone is 450~650℃; the temperature of the transition zone is 700~800℃; the temperature of the high temperature zone is 900~1000℃; the temperature of the water cooling jacket is ≤60℃; and the moving speed of the material boat is 0.9~1.2 m / h.
[0018] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention employs a unique gas distribution design, specifically by placing several open gas boxes within the furnace tube and extending inlet pipes through these boxes. Hydrogen gas is introduced into each open gas box through outlet holes on the inlet pipe. Utilizing the low density of hydrogen, it is concentrated within the open gas boxes. Gas diffusion ensures uniform pressure at every point near the material (metal oxide) within each open gas box, achieving uniform gas distribution. This also ensures even distribution of hydrogen throughout the furnace tube, maintaining consistent gas concentration and partial pressure in contact with the material. This eliminates the uneven reaction rate caused by gas concentration gradients in traditional processes, allowing the reaction to proceed synchronously and uniformly at all points, laying the foundation for precise control of the reaction process and product morphology. 2. The device described in this invention can guide the directional flow of hydrogen, enabling excess hydrogen to promptly carry away byproducts (such as water vapor) and impurities generated during the reaction from the material surface and rapidly discharge them through the exhaust pipe. This mechanism effectively avoids the accumulation of byproducts in the reaction zone, prevents byproducts from returning to the material to participate in the reaction, and maintains a low partial pressure of byproducts on the material surface, thereby significantly increasing the rate at which byproducts escape, continuously driving the reaction forward, and significantly improving both the overall reaction rate and product purity. 3. The uniform gas distribution design and efficient by-product removal mechanism of the device described in this invention jointly suppress abnormal grain growth caused by differences in local reaction conditions, which is beneficial for obtaining metal powders with uniform particle size and controllable morphology. At the same time, the device also effectively improves the utilization efficiency of hydrogen and the overall efficiency of the reaction process, which not only improves the purity and yield of the metal powder, but also ensures the consistency of product quality. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0020] Figure 1 This is a front cross-sectional view of the apparatus for preparing metal powder by constant concentration gas-solid reduction according to the present invention; Figure 2 This is a side cross-sectional view of the furnace tube in the apparatus for preparing metal powder by constant concentration gas-solid reduction according to the present invention. Figure 3 This is a front cross-sectional view of the furnace tube in the apparatus for preparing metal powder by constant concentration gas-solid reduction according to the present invention. Figure 4 This is a top sectional view of the furnace tube in the apparatus for preparing metal powder by constant concentration gas-solid reduction according to the present invention. Figure 5The image shows the morphology of qualified molybdenum powder. Figure 6 The image shows the morphology of the molybdenum powder prepared in Example 1. Figure 7 The graph shows the oxygen content detection results of the molybdenum powder prepared in Example 1. The components include: 1. Boat pushing mechanism; 2. Furnace body; 3. Water cooling jacket; 4. Boat unloading mechanism; 5. Furnace tube; 6. Furnace tube body; 7. First furnace door; 8. Second furnace door; 9. Exhaust vent; 10. Open gas box; 11. Material boat; 12. Air inlet pipe; 13. Air outlet; 14. Heating device; 15. Heating element; 16. Exhaust pipe. Detailed Implementation
[0021] This invention provides an apparatus for preparing metal powder by constant concentration gas-solid reduction, the front cross-sectional view of which is shown below. Figure 1 As shown, the side sectional view of furnace tube 5 is as follows: Figure 2 As shown, the front sectional view of furnace tube 5 is as follows: Figure 3 As shown, the top sectional view of furnace tube 5 is as follows: Figure 4 As shown, through Figures 1-4 It can be seen that the device includes a boat-pushing mechanism 1, a furnace body 2, a water-cooling jacket 3, and a boat-discharging mechanism 4, which are connected in sequence. The furnace body 2 includes a furnace tube 5, an open gas box 10, a material boat 11, an air inlet pipe 12, and a heating device 14; The boat-pushing mechanism 1 is connected to the furnace body 2 through one end of the furnace tube 5, and is used to push the material boat 11 into the interior of the furnace tube 5; the water-cooling jacket 3 is connected to the furnace body 2 through the other end of the furnace tube 5; The furnace tube 5 is a closed furnace tube, including the furnace tube body 6, the first furnace door 7, the second furnace door 8, and the exhaust port 9; The first furnace door 7 and the second furnace door 8 are respectively installed at both ends of the furnace tube body 6. The material boat 11 enters the interior of the furnace tube body 6 through the first furnace door 7 and exits the interior of the furnace tube body 6 through the second furnace door 8. The exhaust port 9 is located on the side surface of the furnace tube body 6 near the first furnace door 7; A plurality of open gas boxes 10 are provided, and the plurality of open gas boxes 10 are evenly arranged on the upper surface inside the furnace tube body 6, and the opening of the open gas box 10 faces downward; the opening facing downward means that the opening of the open gas box 10 is facing the ground. Several material boats 11 are provided, and several material boats 11 are slidably connected to the lower surface inside the furnace tube body 6 in sequence, and the opening of the material boat 11 faces upward; the opening facing upward means that the opening of the material boat 11 is facing away from the ground. The air inlet pipe 12 passes through the first furnace door 7 and the second furnace door 8 and is installed inside the several open gas boxes 10 for introducing hydrogen into the several open gas boxes 10. The heating device 14 is disposed on the outer surface of the furnace tube body 6.
[0022] In this invention, the width of the open gas box 10 is equal to the width of the material boat 11, and the distance between the two ends of the open gas box 10 in the width direction and the inner wall of the furnace tube body 6 in the width direction is preferably 20~30 mm, more preferably 22~28 mm, and more preferably 25 mm; the space of this distance serves as the exhaust channel for hydrogen to flow from the open gas box 10 to the exhaust port 9.
[0023] In this invention, the depth of the open gas box 10 is ≥60 mm, preferably 61~80 mm, more preferably 65~75 mm, and even more preferably 70 mm; the open gas box 10 at this depth can include the inlet pipe 12 and allow for the diffusion distance of hydrogen; the distance between the open gas box 10 and the material boat 11 in the depth direction is 30~40 mm, preferably 32~38 mm, more preferably 33~36 mm, and even more preferably 35 mm; this distance can ensure that the material boat 11 does not interfere with the open gas box 10 when it moves, and can also leave a channel for the hydrogen and water vapor to be discharged; the length of the open gas box 10 and the material boat 11 independently is 200~400 mm, preferably 220~380 mm, more preferably 250~350 mm, and even more preferably 300 mm.
[0024] In this invention, the length of the open air box 10 is greater than or equal to the length of the material boat 11.
[0025] In this invention, the surface of the inlet pipe 12 is provided with a plurality of outlet holes 13, and each outlet hole 13 is located inside the open gas box 10, preferably in the middle position inside the open gas box 10. After hydrogen enters the open gas box 10 through the outlet hole 13, due to the characteristic that the density of hydrogen is much lower than that of water vapor, the hydrogen will concentrate upward in the open gas box 10 and be gathered in the open gas box 10. At the same time, due to gas diffusion, the pressure at every point of the material in the material boat 11 near the open gas box 10 is the same, which plays a role in uniform gas distribution and makes the hydrogen concentration at each position in the furnace tube 5 the same, thereby improving the reaction rate.
[0026] In this invention, the principle of the directional flow of hydrogen is as follows: the pressure P0 in the inlet pipe 12 > the pressure P1 in the open gas box 10 > the pressure P2 in the exhaust channel. Since the pressure P0 in the inlet pipe 12 is much greater than the pressure P1 in the open gas box 10, hydrogen can quickly enter the open gas box 10, causing the pressure in the open gas box 10 to tend to increase. Meanwhile, the exhaust channel is connected to the outside of the furnace tube 5, and the pressure tends to be atmospheric pressure (0 MPa). At the same time, since gas always flows from a place with high pressure to a place with low pressure, the direction of hydrogen flow in the furnace tube 5 is a directional flow from the inlet pipe 12 to the open gas box 10 and then to the exhaust channel to the exhaust pipe 16. Moreover, since there is no pressure difference between each open gas box 10 due to the same gas volume, the hydrogen between the open gas boxes 10 will not flow to each other. The hydrogen will only flow along the exhaust channels on both sides to the exhaust pipe 16 for discharge. The flowing hydrogen gas continuously carries away water vapor and impurities from the material surface, preventing them from contacting the material and participating in the reaction. This ensures that the water vapor partial pressure on the material surface remains at a low level and guarantees the high uniformity of the particle size and low oxygen content of the generated metal powder.
[0027] In this invention, the heating device 14 includes a plurality of heating elements 15, which are uniformly arranged on the outer surface of the furnace tube body 6.
[0028] In this invention, an exhaust pipe 16 is also included, which is connected to the furnace tube body 6 through the exhaust hole 9.
[0029] In this invention, the interior of the furnace tube body 6 is sequentially provided with a preheating temperature zone, a low temperature zone, a transition temperature zone, and a high temperature zone from the first furnace door 7 to the second furnace door 8; the length of the preheating temperature zone is 1~1.6 m, preferably 1.1~1.5 m, more preferably 1.2~1.4 m, and more preferably 1.3 m; the length of the low temperature zone is 1~1.6 m, preferably 1.1~1.5 m, more preferably 1.2~1.4 m, and more preferably 1.3 m; the length of the transition temperature zone is 1~1.6 m, preferably 1.1~1.5 m, more preferably 1.2~1.4 m, and more preferably 1.3 m; the length of the high temperature zone is 3.6~6 m, preferably 3.8~5.8 m, more preferably 4~5.5 m, and more preferably 4.5~5 m; the length of the water-cooling jacket is 1~2 m, preferably 1.1~1.8 m, more preferably 1.2~1.6 m, and more preferably 1.5 m.
[0030] The present invention also provides a method for preparing metal powder using the above-described apparatus with constant concentration gas-solid reduction, comprising the following steps: Metal oxides are loaded into the material boat 11. After the heating device 14 heats the furnace tube 5 and hydrogen is introduced into the open gas box 10 through the gas inlet pipe 12, the boat pushing mechanism 1 pushes the material boat 11 from the first furnace door 7 of the furnace tube 5 to the preheating temperature zone, low temperature zone, transition temperature zone and high temperature zone of the furnace tube 5 in sequence, and performs preheating, first-stage reduction reaction, heating and second-stage reduction reaction accordingly. Then the material boat 11 is pushed from the second furnace door 8 of the furnace tube 5 to the water cooling jacket 3 for cooling. Finally, the material is discharged by the boat discharge mechanism 4 to obtain metal powder. At the same time, hydrogen carrying water vapor and impurity elements is discharged from the furnace tube 5 through the exhaust pipe 16.
[0031] In this invention, the metal oxide is preferably molybdenum trioxide, tungsten trioxide, iron oxide, copper oxide, or ammonium perrhenate.
[0032] In this invention, the thickness of the metal oxide filling is 60-100% of the depth of the boat 11, preferably 65-95%, more preferably 70-90%, and even more preferably 80-85%.
[0033] In this invention, the hydrogen inlet pressure is 0.1~0.2 MPa, preferably 0.12~0.18 MPa, more preferably 0.13~0.17 MPa, and even more preferably 0.15 MPa; the temperature of the preheating zone is 400~650℃, preferably 420~600℃, more preferably 450~550℃, and even more preferably 500℃; the preheating zone is used to preheat the material; the temperature of the low-temperature zone is 450~650℃, preferably 470~600℃, more preferably 500~580℃, and even more preferably 550℃; the low-temperature zone is used for a single-stage reduction reaction of the metal oxide; the temperature of the transition zone is 700~800℃, preferably 720~780℃, more preferably 730~760℃, and even more preferably 750℃; the transition zone is used to reduce the temperature between the low-temperature zone and the high-temperature zone. The temperature gradient between the two zones also serves to heat the material; the temperature of the high-temperature zone is 900~1000℃, preferably 910~980℃, more preferably 920~960℃, and even more preferably 950℃; the high-temperature zone is used for the second-stage reduction reaction of the first-stage reduction product; the temperature of the water-cooled jacket 3 is ≤60℃, preferably 10~55℃, more preferably 15~40℃, and even more preferably 20~30℃; the water-cooled jacket 3 is used to cool the material, so that the temperature of the material boat 11 and the material drops below 60℃ when they are pushed out of the device, to avoid oxidation of the metal powder and facilitate personnel operation; the moving speed of the material boat 11 is 0.9~1.2 m / h, preferably 0.95~1.15 m / h, and even more preferably 1.0~1.1 m / h.
[0034] The technical solutions provided by the present invention will be 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.
[0035] Example 1
[0036] Molybdenum trioxide is filled into a boat (300 mm long, 280 mm wide, and 30 mm deep), and the thickness of the material layer is precisely controlled to be 100% of the boat depth. Then, the furnace tube (9000 mm long, 320 mm wide, and 120 mm deep) is heated to a temperature of 600°C in the preheating zone, 600°C in the low-temperature zone, 800°C in the transition zone, and 1000°C in the high-temperature zone. Hydrogen gas is introduced at a pressure of 0.2 MPa through outlet holes on the surface of the inlet pipe into 24 open gas boxes (300 mm long, 280 mm wide, and 60 mm deep). The hydrogen gas first accumulates above the open gas boxes and then flows downwards via gas diffusion. A boat-pushing mechanism then propels the boat at a constant speed of 0.9 m / h within the furnace tube, sequentially passing through the preheating zone, low-temperature zone, transition zone, and high-temperature zone (the preheating zone is 1.2 m long). The lengths of the low-temperature zone, the transition temperature zone, and the high-temperature zone are 1.2 m, 1.2 m, and 3.6 m respectively. At this point, hydrogen gas flows over the material boat, diffuses downwards, and comes into contact with molybdenum trioxide. This process involves preheating, a first-stage reduction reaction (molybdenum trioxide is reduced to molybdenum dioxide, which does not agglomerate and has good permeability), heating, and a second-stage reduction reaction (molybdenum dioxide reacts with hydrogen to produce molybdenum powder). Then, the boat-pushing mechanism continues to push the material boat at a constant speed of 0.9 m / h through the second furnace door into a 20°C water-cooled jacket (1.5 m long) for cooling. Finally, the material is discharged by the boat-discharging mechanism to obtain molybdenum powder. At the same time, excess hydrogen gas in the furnace tube carries water vapor and volatile impurities through the exhaust channels formed by the material boat and the open gas box on both sides of the furnace tube, and flows to the exhaust pipe to be discharged from the furnace tube.
[0037] This embodiment uses, as follows: Figures 1-4 The apparatus shown was used for constant-concentration gas-solid reduction to prepare metallic molybdenum powder. Morphological characterization experiments were performed on the molybdenum powder obtained in this embodiment and on qualified molybdenum powder (batch number 2226017074, standard Q / MBN.03.074-2021) produced using a conventional apparatus. The results are as follows. Figures 5-6 As shown, where, Figure 5 The image shows the morphology of qualified molybdenum powder produced by conventional equipment. Figure 6 The image shows the morphology of the molybdenum powder prepared in Example 1. Figures 5-6 As can be seen, the molybdenum powder produced using the device of the present invention has fewer abnormally large particles, and the morphology and particle size distribution of the molybdenum powder are significantly improved.
[0038] Furthermore, the oxygen content of the molybdenum powder prepared in Example 1 was determined by Steel Research Institute NAK Co., Ltd. using infrared absorption method, and the detection results are as follows: Figure 7 As shown, from Figure 7 As can be seen from the data, the average oxygen content of the molybdenum powder prepared in Example 1 is less than 300 ppm.
[0039] Example 2
[0040] Tungsten trioxide is loaded into a boat (300 mm long, 280 mm wide, and 25 mm deep), and the thickness of the material layer is precisely controlled to be 100% of the boat's depth. The furnace tube (9000 mm long, 320 mm wide, and 120 mm deep) is then heated to 650°C in the preheating zone, 650°C in the low-temperature zone, 750°C in the transition zone, and 900°C in the high-temperature zone. Hydrogen gas is introduced at a pressure of 0.2 MPa through outlets on the surface of the inlet pipe into 24 open gas boxes (300 mm long, 280 mm wide, and 60 mm deep). The hydrogen gas first accumulates above the open gas boxes and then diffuses downwards. A boat-pushing mechanism then propels the boat at a constant speed of 1.2 m / h within the furnace tube, sequentially passing through the preheating zone, low-temperature zone, transition zone, and high-temperature zone (the preheating zone is 1.2 m long). The lengths of the low-temperature zone, the transition temperature zone, and the high-temperature zone are 1.2 m, 1.2 m, and 3.6 m respectively. At this point, hydrogen gas flows over the top of the material boat, diffuses downwards, and comes into contact with tungsten trioxide. This process involves preheating, a first-stage reduction reaction (tungsten trioxide is reduced to tungsten dioxide, which does not agglomerate and has good permeability), heating, and a second-stage reduction reaction (tungsten dioxide reacts with hydrogen to produce tungsten powder). Then, the boat-pushing mechanism continues to push the material boat at a constant speed of 1.2 m / h through the second furnace door into a 20°C water-cooled jacket (1.5 m long) for cooling. Finally, the material is discharged by the boat-discharging mechanism to obtain tungsten powder. At the same time, excess hydrogen gas in the furnace tube carries water vapor and volatile impurities through the exhaust channels formed by the material boat and the open gas box on both sides of the furnace tube, and flows to the exhaust pipe to be discharged from the furnace tube.
[0041] This embodiment uses, as follows: Figures 1-4 The apparatus shown was used to prepare metallic tungsten powder using a constant-concentration gas-solid reduction method. Tungsten powder of acceptable quality was obtained.
[0042] Example 3
[0043] Ammonium perrhenate is loaded into a boat (300 mm long, 280 mm wide, and 20 mm deep), and the material layer thickness is precisely controlled to be 60% of the boat depth. The furnace tube (9000 mm long, 320 mm wide, and 120 mm deep) is then heated to 450°C in the preheating zone, 450°C in the low-temperature zone, 700°C in the transition zone, and 900°C in the high-temperature zone. Hydrogen gas is then introduced into 24 open gas boxes (300 mm long, 280 mm wide, and 60 mm deep) through outlets on the surface of the inlet pipe at a pressure of 0.2 MPa. The hydrogen gas first accumulates above the open gas boxes and then flows downwards via diffusion. A boat-pushing mechanism then propels the boat at a constant speed of 0.9 m / h within the furnace tube, sequentially passing through the preheating zone, low-temperature zone, transition zone, and high-temperature zone (the preheating zone is 1.2 m long). The lengths of the low-temperature zone, the transition temperature zone, and the high-temperature zone are 1.6 m, 1.2 m, and 3.6 m respectively. At this point, hydrogen gas flows over the top of the material boat, diffuses downwards, and comes into contact with ammonium perrhenate. This process involves preheating, a first-stage reduction reaction (ammonium perrhenate is reduced to rhenium dioxide), heating, and a second-stage reduction reaction (rhenium dioxide reacts with hydrogen to produce rhenium powder). Then, the boat-pushing mechanism continues to push the material boat at a constant speed of 0.9 m / h through the second furnace door into a 20°C water-cooled jacket (1.5 m long) for cooling. Finally, the material is discharged by the boat-discharging mechanism to obtain rhenium powder. At the same time, excess hydrogen gas in the furnace tube carries water vapor and volatile impurities through the exhaust channels formed by the material boat and the open gas box on both sides of the furnace tube, and flows to the exhaust pipe to be discharged from the furnace tube.
[0044] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. An apparatus for preparing metal powder by constant concentration gas-solid reduction, characterized in that, It includes a boat-pushing mechanism, a furnace body, a water-cooling jacket, and a boat-discharging mechanism that are connected in sequence. The furnace body includes furnace tubes, an open gas box, a material boat, an air inlet pipe, and a heating device; The boat-pushing mechanism is connected to the furnace body through one end of the furnace tube and is used to push the material boat into the interior of the furnace tube; the water-cooling jacket is connected to the furnace body through the other end of the furnace tube. The furnace tube is a closed furnace tube, including the furnace tube body, the first furnace door, the second furnace door, and the exhaust port; The first furnace door and the second furnace door are respectively installed at both ends of the furnace tube body. The material boat enters the interior of the furnace tube body through the first furnace door and leaves the furnace tube body through the second furnace door. The exhaust port is located on the side surface of the furnace tube body near the first furnace door; The open gas box is provided in several parts, and the open gas box is evenly arranged on the upper surface inside the furnace tube body, with the opening of the open gas box facing downward. The material boats are provided in a plurality of manner, and the plurality of material boats are slidably connected in sequence to the lower surface inside the furnace tube body, with the openings of the material boats facing upwards; The gas inlet pipe passes through the first furnace door and the second furnace door and is installed inside the several open gas boxes for introducing hydrogen into the several open gas boxes; The heating device is disposed on the outer surface of the furnace tube body.
2. The apparatus for preparing metal powder by constant concentration gas-solid reduction according to claim 1, characterized in that, The width of the open gas box is equal to the width of the material boat, and the distance between both ends of the open gas box in the width direction and the inner wall of the furnace tube body in the width direction is 20~30 mm. The depth of the open air box is ≥60 mm; The distance between the open air box and the material boat in the depth direction is 30~40 mm; The length of the open air box and the material boat are independent of each other, ranging from 200 to 400 mm.
3. The apparatus for preparing metal powder by constant concentration gas-solid reduction according to claim 2, characterized in that, The surface of the air inlet pipe is provided with several air outlet holes, and each air outlet hole is located inside the open gas box for introducing hydrogen gas into the interior of the open gas box.
4. The apparatus for preparing metal powder by constant concentration gas-solid reduction according to any one of claims 1 to 3, characterized in that, The heating device includes a plurality of heating elements, which are uniformly arranged on the outer surface of the furnace tube body.
5. The apparatus for preparing metal powder by constant concentration gas-solid reduction according to claim 4, characterized in that, It also includes an exhaust pipe, which is connected to the furnace tube body through the exhaust port.
6. The apparatus for preparing metal powder by constant concentration gas-solid reduction according to claim 5, characterized in that, The interior of the furnace tube body is sequentially arranged with a preheating temperature zone, a low temperature zone, a transition temperature zone, and a high temperature zone from the first furnace door to the second furnace door; the length of the preheating temperature zone is 1~1.6 m, the length of the low temperature zone is 1~1.6 m, the length of the transition temperature zone is 1~1.6 m, and the length of the high temperature zone is 3.6~6 m. The length of the water-cooling jacket is 1~2 m.
7. A method for preparing metal powder using the apparatus according to any one of claims 1 to 6 with constant concentration gas-solid reduction, characterized in that, Includes the following steps: Metal oxides are loaded into a material boat. After the heating device heats the furnace tube and hydrogen is introduced into the open gas box through the gas inlet pipe, the boat pushing mechanism pushes the material boat from the first furnace door of the furnace tube to the preheating temperature zone, low temperature zone, transition temperature zone and high temperature zone of the furnace tube in sequence, and performs preheating, first-stage reduction reaction, heating and second-stage reduction reaction accordingly. Then the material boat is pushed from the second furnace door of the furnace tube to the water cooling jacket for cooling. Finally, the material is discharged by the boat discharge mechanism to obtain metal powder. At the same time, hydrogen carrying water vapor and impurity elements is discharged from the furnace tube through the exhaust pipe.
8. The method for preparing metal powder by constant concentration gas-solid reduction according to claim 7, characterized in that, The metal oxide is molybdenum trioxide, tungsten trioxide, iron oxide, copper oxide, or ammonium perrhenate.
9. The method for preparing metal powder by constant concentration gas-solid reduction according to claim 8, characterized in that, The thickness of the metal oxide filling is 60-100% of the depth of the boat.
10. The method for preparing metal powder by constant concentration gas-solid reduction according to claim 9, characterized in that, The hydrogen gas is introduced at a pressure of 0.1~0.2 MPa; The temperature of the preheating zone is 400~650℃; The temperature of the low-temperature zone is 450~650℃; The temperature of the transition temperature zone is 700~800℃; The temperature in the high-temperature zone is 900~1000℃; The temperature of the water-cooled jacket is ≤60℃; The moving speed of the material boat is 0.9~1.2 m / h.