Fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder

Abstract

The invention belongs to the technical field of powder metallurgy, and particularly relates to a fluidized bed auxiliary micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder, which comprises the following steps: pouring raw material molybdenum powder into a fluidized bed auxiliary micro-oxidation device for micro-oxidation; the molybdenum powder subjected to micro-oxidation treatment is added into an ammonia water solution to be fully stirred, and precipitates are filtered out after reaction; and the precipitate is cleaned and then dried in a protective atmosphere, and the spherical molybdenum powder is obtained. The method is efficient in overall process and low in cost, and the spherical molybdenum powder obtained through the method is high in sphericity, good in fluidity and high in purity. The method can be used for producing the spherical molybdenum powder with various particle sizes, the sphericity and fluidity of the molybdenum powder are greatly improved through targeted regulation and control of technological parameters, and the method has wide application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of powder metallurgy, in particular to a fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder. Background Art

[0002] Metallic molybdenum is a strategically important refractory rare metal with high temperature strength and hardness, high melting point, good electrical and thermal conductivity, small expansion coefficient, excellent thermal shock resistance and thermal fatigue resistance. Spherical molybdenum powder has high fluidity and high bulk density, and is widely used in 3D printing, thermal spraying, surfacing, contact material preparation, powder metallurgy and other fields. The preparation methods of spherical molybdenum powder include rotating electrode method, spray granulation method, plasma spheroidization method and the like. Among them, the plasma spheroidization method and the rotating electrode method for preparing spherical powder have complex equipment and high energy consumption, while the spherical molybdenum powder prepared by the spray granulation method has the disadvantages of high oxygen content, large powder particle size and wide particle size distribution range. With the development of technology, spherical molybdenum powder needs to better meet the requirements of high sphericity, high purity, high fluidity, high tap density, high dispersibility, low energy consumption and low cost. Therefore, it is imperative to seek the most optimized spherical molybdenum powder preparation equipment and method. Summary of the invention

[0003] In order to solve the problems existing in the prior art, the main purpose of the present invention is to propose a fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder.

[0004] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0005] A fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder comprises the following steps:

[0006] S1, pouring raw molybdenum powder into a fluidized bed assisted micro-oxidation device for micro-oxidation;

[0007] S2, adding the molybdenum powder that has been subjected to micro-oxidation treatment into an ammonia solution and stirring for 1 to 60 minutes, and filtering out the precipitate after the reaction;

[0008] S3, washing the precipitate, and then drying it under a protective atmosphere to obtain spherical molybdenum powder.

[0009] As a preferred embodiment of the fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder described in the present invention, wherein: in the step S1, the raw material molybdenum powder is molybdenum powder with irregular morphology.

[0010] As a preferred embodiment of the fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder described in the present invention, wherein: in the step S1, the fluidized bed assisted micro-oxidation device includes a shell, an inlet arranged at the top of the shell, and the inlet is connected to a drying zone, a gas fluidized bed is arranged in the middle of the drying zone, a heater is arranged on the outside of the gas fluidized bed, and an air outlet and an air inlet are respectively arranged at the top and bottom of the drying zone, and the lower end of the shell is a discharge port.

[0011] As a preferred embodiment of the fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder described in the present invention, wherein: in the step S1, the raw molybdenum powder is poured into the fluidized bed assisted micro-oxidation device through the feed inlet, falls into the gas fluidized bed after preliminary drying in the drying zone, and compressed gas is blown into the gas fluidized bed from the air inlet, so that the raw molybdenum powder is suspended on the gas fluidized bed, and at the same time, the heater micro-oxidizes the raw molybdenum powder, and the gas in the process is discharged through the air outlet. After the micro-oxidation is completed, the air flow at the air inlet is closed, and the discharge port is opened to complete the collection of the molybdenum powder treated with micro-oxidation.

[0012] As a preferred embodiment of the fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder described in the present invention, wherein: in the step S1, the micro-oxidation temperature is 200-700°C, and the micro-oxidation time is 1-120 minutes.

[0013] As a preferred embodiment of the fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder described in the present invention, wherein: in the step S2, the concentration of the ammonia solution is 1 to 28 wt%.

[0014] As a preferred embodiment of the fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder described in the present invention, wherein: in the step S2, the solution temperature during the stirring process is 20-100°C.

[0015] As a preferred embodiment of the fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder described in the present invention, wherein: in the step S3, the precipitate is washed with deionized water or alcohol.

[0016] As a preferred embodiment of the fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder described in the present invention, wherein: in the step S3, the drying temperature is 20-100°C.

[0017] As a preferred embodiment of the fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder described in the present invention, wherein: in the step S3, the protective atmosphere is one of argon, hydrogen and nitrogen.

[0018] To solve the above technical problem, according to another aspect of the present invention, the present invention provides the following technical solution:

[0019] A spherical molybdenum powder prepared by the fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder.

[0020] The beneficial effects of the present invention are as follows:

[0021] The present invention proposes a fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder, wherein the raw molybdenum powder is poured into a fluidized bed assisted micro-oxidation device for micro-oxidation; the molybdenum powder treated with micro-oxidation is added to an ammonia solution and stirred sufficiently, and the precipitate is filtered out after the reaction; the precipitate is washed and then dried under a protective atmosphere to obtain spherical molybdenum powder. The overall process of the method of the present invention is efficient and low in cost, and the spherical molybdenum powder obtained by the method of the present invention has high sphericity, good fluidity and high purity. The present invention can be used to produce spherical molybdenum powders of various particle sizes. Through targeted regulation of process parameters, the sphericity and fluidity of the molybdenum powder are greatly improved, and it has broad application prospects. 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 some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0023] Figure 1 It is a schematic structural diagram of the fluidized bed assisted micro-oxidation device of the present invention.

[0024] Figure 2 This is a scanning electron microscope photograph of the spherical molybdenum powder prepared in Example 1 of the present invention.

[0025] Figure 3 This is a scanning electron microscope photograph of the molybdenum powder prepared in Comparative Example 1 of the present invention.

[0026] In the figure, 1-feeding port, 2-drying zone, 3-heater, 4-discharge port, 5-gas outlet, 6-gas fluidized bed, 7-gas inlet.

[0027] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0028] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The main purpose of the present invention is to propose a fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder. Irregular molybdenum powder is placed in a fluidized bed assisted micro-oxidation device for surface oxidation treatment. The purpose is to preferentially oxidize the surface edges and corners of the irregular molybdenum powder. After the molybdenum powder enters the micro-oxidation zone, it is micro-oxidized on a gas fluidized bed micro-oxidation device. The gas fluidized bed micro-oxidation device ensures the overall uniformity of powder micro-oxidation, improves the dispersibility of the powder, and solves the continuity of the micro-oxidation process. The molybdenum powder after micro-oxidation is immersed in an ammonia solution for ammonia stripping treatment. The overall process is efficient and low-cost. The present invention adopts a fluidized bed assisted micro-oxidation-ammonia stripping method to prepare spherical molybdenum powder. Micro-oxidation not only ensures the overall uniformity of powder micro-oxidation, but also allows each edge and corner of the irregular molybdenum powder to be uniformly oxidized. Moreover, the oxidation time is short, which improves the dispersibility of the powder, solves the problem of easy agglomeration of the powder during the micro-oxidation process, and enhances the sphericity and fluidity of the spherical molybdenum powder finally obtained. At the same time, the efficiency of the micro-oxidation process is ensured. The whole process is efficient and simple, which is conducive to mass production and processing.

[0030] like Figure 1 As shown, the fluidized bed assisted micro-oxidation device includes a shell, an inlet 1 arranged at the top of the shell, the inlet 1 is connected to the drying zone 2, a gas fluidized bed 6 is arranged in the middle of the drying zone 2, a heater 3 is arranged outside the gas fluidized bed 6, and the drying zone 2 has an outlet 5 and an inlet 7 at the top and bottom, respectively, and the lower end of the shell is a discharge port 4. The raw molybdenum powder is poured into the fluidized bed assisted micro-oxidation device through the inlet 1, falls into the gas fluidized bed 6 after preliminary drying in the drying zone 2, and the compressed gas is blown into the gas fluidized bed 6 from the inlet 7, so that the raw molybdenum powder is suspended on the gas fluidized bed 6, and at the same time, the heater 3 performs micro-oxidation on the raw molybdenum powder, and the gas in the process is discharged through the outlet 5. After the micro-oxidation is completed, the airflow of the inlet 7 is closed, and the discharge port 4 is opened to complete the collection of the molybdenum powder treated with micro-oxidation.

[0031] The technical solution of the present invention is further described below in conjunction with specific embodiments, in which the above-mentioned fluidized bed assisted micro-oxidation device is adopted.

[0032] Example 1

[0033] A method for preparing spherical molybdenum powder comprises the following steps: screening the initial raw material molybdenum powder, pouring the raw material molybdenum powder with irregular morphology and an average particle size of 5 μm after screening into a fluidized bed assisted micro-oxidation device, controlling the micro-oxidation temperature to 300°C and the micro-oxidation time to 20 minutes. The molybdenum powder that has been subjected to micro-oxidation treatment is added to an ammonia solution with a concentration of 26 wt%, and stirred for 10 minutes at 20°C. After the reaction, the precipitate is filtered out. The precipitate after ammonia stripping is washed with deionized water, and the washed powder is dried at 80°C under argon protection to finally obtain spherical molybdenum powder, and a scanning electron microscope photograph thereof is shown as follows: Figure 2 As shown, it can be seen that the spherical molybdenum powder obtained by the present invention has high sphericity, good fluidity and high purity.

[0034] Example 2

[0035] A method for preparing spherical molybdenum powder comprises the following steps: screening the initial raw material molybdenum powder, pouring the raw material molybdenum powder with an irregular morphology and an average particle size of 5 μm after screening into a fluidized bed assisted micro-oxidation device, controlling the micro-oxidation temperature to be 400° C., and the micro-oxidation time to be 20 minutes. The molybdenum powder treated with micro-oxidation is added into an ammonia solution with a concentration of 26wt%, fully stirred at a temperature of 20° C. for 10 minutes, and filtering out the precipitate after the reaction. The precipitate after ammonia stripping is washed with deionized water, and the washed powder is dried at 80° C. under argon protection to finally obtain spherical molybdenum powder.

[0036] Example 3

[0037] A method for preparing spherical molybdenum powder comprises the following steps: screening the initial raw material molybdenum powder, pouring the raw material molybdenum powder with an irregular morphology and an average particle size of 10 μm after screening into a fluidized bed assisted micro-oxidation device, controlling the micro-oxidation temperature to be 400° C., and the micro-oxidation time to be 20 minutes. The molybdenum powder treated with micro-oxidation is added into an ammonia solution with a concentration of 26wt%, fully stirred at a temperature of 50° C. for 10 minutes, and filtering out the precipitate after the reaction. The precipitate after ammonia stripping is washed with deionized water, and the washed powder is dried at 80° C. under argon protection to finally obtain spherical molybdenum powder.

[0038] Example 4

[0039] A method for preparing spherical molybdenum powder comprises the following steps: screening the initial raw material molybdenum powder, pouring the raw material molybdenum powder with an irregular morphology and an average particle size of 10 μm after screening into a fluidized bed assisted micro-oxidation device, controlling the micro-oxidation temperature to be 400° C., and the micro-oxidation time to be 10 minutes. The molybdenum powder treated with micro-oxidation is added into an ammonia solution with a concentration of 26 wt%, and fully stirred at a temperature of 50° C. for 10 minutes, and filtering out the precipitate after the reaction. The precipitate after ammonia stripping is washed with deionized water, and the washed powder is dried at 80° C. under argon protection, and finally the spherical molybdenum powder is obtained.

[0040] Example 5

[0041] A method for preparing spherical molybdenum powder comprises the following steps: screening the initial raw material molybdenum powder, pouring the raw material molybdenum powder with an irregular morphology and an average particle size of 15 μm after screening into a fluidized bed assisted micro-oxidation device, controlling the micro-oxidation temperature to be 300° C., and the micro-oxidation time to be 30 minutes. The molybdenum powder treated with micro-oxidation is added into an ammonia solution with a concentration of 15wt%, fully stirred at a temperature of 50° C. for 20 minutes, and filtering out the precipitate after the reaction. The precipitate after ammonia stripping is washed with deionized water, and the washed powder is dried at 80° C. under argon protection to finally obtain spherical molybdenum powder.

[0042] Comparative Example 1

[0043] A method for preparing molybdenum powder comprises screening the initial raw material molybdenum powder, adding the raw material molybdenum powder with an average particle size of 5 μm after screening and irregular morphology to an ammonia solution with a concentration of 26 wt%, stirring the mixture for 10 minutes at a temperature of 20°C, filtering out the precipitate after the reaction, washing the precipitate after ammonia stripping with deionized water, drying the washed powder at 80°C under argon protection, and finally obtaining a molybdenum powder such as Figure 3 As shown, the molybdenum powder has obvious edges and corners, and has no obvious change compared with the raw material molybdenum powder.

[0044] The raw material molybdenum powder of the present invention is poured into a fluidized bed assisted micro-oxidation device for micro-oxidation; the molybdenum powder treated with micro-oxidation is added to an ammonia solution and stirred sufficiently, and the precipitate is filtered out after the reaction; the precipitate is washed and then dried under a protective atmosphere to obtain spherical molybdenum powder. The overall process of the method of the present invention is efficient and low in cost. The spherical molybdenum powder obtained by the method of the present invention has high sphericity, good fluidity and high purity. The present invention can be used to produce spherical molybdenum powders of various particle sizes. Through targeted regulation of process parameters, the sphericity and fluidity of the molybdenum powder are greatly improved, and it has broad application prospects.

[0045] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder, characterized in that: The steps include: S1, pouring raw molybdenum powder into a fluidized bed assisted micro-oxidation device for micro-oxidation; S2, adding the molybdenum powder that has been subjected to micro-oxidation treatment into an ammonia solution and stirring for 1 to 60 minutes, and filtering out the precipitate after the reaction; S3, washing the precipitate, and then drying it under a protective atmosphere to obtain spherical molybdenum powder.

2. The fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder according to claim 1, characterized in that: In the step S1, the raw material molybdenum powder is molybdenum powder with irregular morphology.

3. The fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder according to claim 1, characterized in that: In step S1, the fluidized bed assisted micro-oxidation device comprises a shell, an inlet (1) arranged at the top of the shell, the inlet (1) is connected to a drying zone (2), a gas fluidized bed (6) is arranged in the middle of the drying zone (2), a heater (3) is arranged outside the gas fluidized bed (6), an air outlet (5) and an air inlet (7) are respectively arranged at the top and bottom of the drying zone (2), and the lowermost end of the shell is a discharge port (4).

4. The fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder according to claim 3, characterized in that: In the step S1, the raw molybdenum powder is poured into the fluidized bed assisted micro-oxidation device through the feed port (1), and falls into the gas fluidized bed (6) after preliminary drying in the drying zone (2). Compressed gas is blown into the gas fluidized bed (6) through the air inlet (7), so that the raw molybdenum powder is suspended on the gas fluidized bed (6). At the same time, the heater (3) micro-oxidizes the raw molybdenum powder, and the gas in the process is discharged through the air outlet (5). After the micro-oxidation is completed, the air flow of the air inlet (7) is closed, and the discharge port (4) is opened to complete the collection of the molybdenum powder that has been treated with micro-oxidation.

5. The fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder according to claim 1, characterized in that: In the step S1, the micro-oxidation temperature is 200-700° C., and the micro-oxidation time is 1-120 min.

6. The fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder according to claim 1, characterized in that: In step S2, the concentration of the aqueous ammonia solution is 1-28 wt %, and the solution temperature is 20-100° C. during stirring.

7. The fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder according to claim 1, characterized in that: In step S3, the precipitate is washed with deionized water or alcohol.

8. The fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder according to claim 1, characterized in that: In step S3, the drying temperature is 20-100°C.

9. The fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder according to claim 1, characterized in that: In step S3, the protective atmosphere is one of argon, hydrogen and nitrogen.

10. Spherical molybdenum powder prepared by the fluidized bed assisted micro-oxidation-ammonia stripping method for preparing spherical molybdenum powder according to any one of claims 1 to 9.

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