Disclosure of Invention
Aiming at the problems, the invention provides a preparation method of high-uniformity granularity controllable metal powder, wherein the metal powder is tungsten powder or molybdenum powder, and the method comprises the following steps:
1) Putting the metal powder raw material into a vacuum oven for vacuum drying;
2) Taking out the dried metal powder raw material from the vacuum oven, carrying out vertical fluidized bed type crushing and grading treatment, setting the range of each technological parameter, and setting the air sealing pressure gauge pressure to be 0.05-0.3MPa and the air quantity of secondary air distribution to be 400-1100m 3 And/h, the powder feeding rate of the feeder is 30-160kg/h, the speed value of the classifier is 140-1300r/min, and the metal powder with controllable granularity and high uniformity is obtained.
Further, in the step 1), the temperature of the vacuum drying is 100-200 ℃, the heat preservation time is 90-120min, and the vacuum degree is 10 -2 Pa。
Further, in step 2), the process parameters are: the pressure of the airtight pressure gauge is 0.1-0.25MPa, and the air quantity of secondary air distribution is 500-1000m 3 And/h, the powder feeding rate of the feeder is 40-150kg/h, and the speed value of the classifier is 150-1200r/min.
Further, in step 1), the temperature of the vacuum drying is 100 ℃, 150 ℃ or 200 ℃, and the heat preservation time is 90min, 105min or 120min.
Further, in step 2), the process parameters are: the pressure of the airtight pressure gauge is 0.1MPa, 0.15MPa, 0.2MPa or 0.25MPa, and the air quantity of the secondary air distribution is 500m 3 /h、600m 3 /h、800m 3 /h or 1000m 3 And/h, the powder feeding rate of the feeder is 40kg/h, 50kg/h, 100kg/h or 150kg/h, and the classifier speed value is 150r/min, 600r/min, 800r/min or 1200r/min.
Further, the step 2) specifically includes the following steps:
2-1) carrying out vertical fluidized bed type crushing and grading treatment, and setting various process parameters;
2-2) taking the dried metal powder raw material out of the vacuum oven, feeding the metal powder raw material into a feeding cylinder, covering a cover, and waiting for starting;
2-3) starting each power supply in the following order: (1) starting a classifier; (2) adjusting a classifier speed regulation table; (3) starting an induced draft fan; (4) starting a blower; (5) starting a feeder;
2-4) starting to work after all the components are started, determining whether the display of the classifying motor, the pressure gauge, the electric control cabinet indicator lamp and the rotating speed is normal or not in the process, and determining whether the powder of the transparent pipeline is conveyed completely or not; after the conveying is finished, the equipment operates for a period of time, the power supply is turned off, and the turn-off sequence of each power supply is opposite to the start sequence in the step 2-3);
2-5) after the equipment is stopped, the receiving hopper is knocked to enable all the powder in the receiving hopper to enter each receiving cylinder, then each receiving cylinder control valve is closed, the powder is taken out, and the whole preparation process is completed.
Further, in step 2-2), the time interval from the removal of the metal powder raw material to the feeding of the metal powder raw material into the feeding cylinder is within 30 minutes.
Further, in the step 2-4), the equipment runs for 5-10min after the conveying is completed.
The invention has the beneficial effects that:
the metal powder purchased in the market at present has wide particle size distribution range and agglomeration, the particle size distribution span of the metal powder is large, the requirement of new generation equipment on the uniformity of the particle size of the metal powder cannot be met, and the uniformity of the metal powder must be improved by treating the powder. The invention provides a preparation method of high-uniformity granularity-controllable metal powder. The metal powder obtained by the method has good uniformity and high production efficiency, and compared with the existing production efficiency, the production efficiency of the method can be improved by more than 7 times, and powder with multiple granularity sections can be obtained. The method adopts a vertical fluidized bed type crushing and grading treatment mode, each particle has the same motion state in the crushing and grading process, the granularity of the product is adjustable, and metal powder with a plurality of granularity sections can be obtained at one time.
In particular, the invention has the advantages that:
1. the fluidized bed crushing cavity is adopted, only compressed air flows through the nozzle, and metal powder collides mutually to realize crushing, so that the crushing abrasion is very small.
2. The vertical classifier is adopted, classification can be better controlled through the flow field, abrasion during classification is greatly eliminated, and purity of metal powder is guaranteed.
3. The induced draft fan and the secondary air blast are combined, and the secondary air can be introduced, so that the lifting force of the metal powder in the air flow is enhanced.
4. Special sealing measures are adopted, compressed air is not consumed, and large particle leakage is prevented.
5. The multiple classifiers are connected in series, so that the crushing efficiency is improved, and the multiple classifiers can be divided into different particle size sections according to requirements, so that the requirements of narrow particle size distribution are greatly met.
6. The powder feeding speed of the invention is 30-160kg/h, and the maximum amount of tungsten powder or molybdenum powder processed according to 8 hours of one working day is 1280kg. Compared with the prior art, the production efficiency and the production capacity of the method can be greatly improved, and the method has the advantages of more uniform distribution of the metal powder, controllable particle size distribution and the like.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The technical scheme of the invention comprises the following process principles: the invention relates to a method for preparing high-uniformity granularity-controllable tungsten powder or molybdenum powder by adopting a vertical fluidized bed type crushing and grading method. The method is that compressed air is accelerated into supersonic airflow and then injected into a crushing area to fluidize tungsten powder or molybdenum powder, and the accelerated particles collide with each other for crushing. Each particle has the same state of motion. The crushed tungsten powder or molybdenum powder is conveyed to a classification area by an ascending air flow, and the powder meeting the granularity requirement is separated by a classifier. The classifying areas are connected in series by multistage classifiers, and powder with multiple particle size sections can be obtained at a time.
Example 1
(1) Putting tungsten powder which is a commercial raw material into a vacuum oven for vacuumAir drying at 100deg.C for 120min with vacuum degree of 10 -2 Pa。
(2) Adopting vertical fluidized bed type crushing and grading treatment, firstly setting each technological parameter, adjusting the air quantity of an induced draft fan and adjusting an airtight pressure gauge to enable the inlet pressure to be 0.1MPa; adjusting the valve of the blower to control the air quantity of the secondary air distribution to be 600m 3 /h; adjusting the feeder to adjust the powder feeding rate to 50kg/h; the classifier speed regulation value was set to 1200r/min.
(3) Taking out the dried tungsten powder from the vacuum oven, feeding into a feeding cylinder (the time interval from taking out the tungsten powder to feeding into the feeding cylinder is not more than 30 minutes), covering a cover, and waiting for starting.
(4) The respective instruments were started up sequentially in the following order: (1) starting a classifier; (2) adjusting a classifier speed regulation table; (3) starting an induced draft fan; (4) starting a blower; (5) the feeder is started.
(5) And after all the components are started, the operation is started, whether the display of the classifying motor, the pressure gauge, the electric control cabinet indicator lamp and the rotating speed is normal or not is determined through observation, and whether the powder of the transparent pipeline is conveyed or not is determined through observation. And (3) operating for 5 minutes after conveying is finished, and turning off the power supply of each instrument, wherein the turn-off sequence of the power supply of each instrument is opposite to the start sequence of the step (4).
(6) After the equipment is stopped, the receiving hopper is beaten by a rubber hammer, so that all the powder in the receiving hopper enters each receiving cylinder, then each receiving cylinder control valve is closed, and the powder is taken out, so that the whole preparation process is completed.
Fig. 1 shows a scanning electron microscope image of the original tungsten powder used, and as can be seen from fig. 1, the original tungsten powder particles have obvious agglomeration phenomenon and uneven particle size distribution. Fig. 2 shows the particle size distribution curve of the original tungsten powder used, and as can be seen from fig. 2, the particle size distribution curve is not a regular normal distribution curve, the curve has irregular protrusions at the coarse particle size distribution, which means that the powder of the coarse particle size section is more than the powder of the fine particle size section, the particle size distribution is uneven, and in addition, the D10 particle size of the powder is 11.470 μm, the D90 is 52.422 μm, and the particle size range of D10-D90 reaches 40.952 μm from the test data.
Fig. 3 is a scanning electron microscope image of the tungsten powder obtained by the method, and it can be seen from fig. 3 that the tungsten powder particles obtained by the method of the invention are all dispersed, have no agglomeration among particles, have small particle size difference, and have uniform particle size distribution.
FIG. 4 shows the particle size distribution curve of the tungsten powder obtained by the above method, and as can be seen from FIG. 4, the particle size distribution curve of the tungsten powder obtained by the method of the present invention is a regular normal distribution curve, the D10 particle size of the powder is 2.635 μm, the D90 is 9.331. Mu.m, and the particle size range of D10-D90 is narrowed to 6.696. Mu.m. The test powder had an average particle size of 3.12. Mu.m.
Example 2
(1) Putting tungsten powder which is a commercial raw material into a vacuum oven for vacuum drying, wherein the drying temperature is 200 ℃, the heat preservation time is 90min, and the vacuum degree is 10 -2 Pa。
(2) Adopting vertical fluidized bed type crushing and grading treatment, firstly setting each technological parameter, adjusting the air quantity of an induced draft fan and adjusting an airtight pressure gauge to enable the inlet pressure to be 0.2MPa; adjusting the valve of the blower to control the air quantity of the secondary air distribution to be 1000m 3 /h; adjusting the feeder to adjust the powder feeding rate to 150kg/h; the classifier speed regulation value was set to 150r/min.
(3) Taking out the dried tungsten powder from the vacuum oven, feeding into a feeding cylinder (the time interval from taking out the tungsten powder to feeding into the feeding cylinder is not more than 30 minutes), covering a cover, and waiting for starting.
(4) The respective instruments were started up sequentially in the following order: (1) starting a classifier; (2) adjusting a classifier speed regulation table; (3) starting an induced draft fan; (4) starting a blower; (5) the feeder is started.
(5) And after all the components are started, the operation is started, whether the display of the classifying motor, the pressure gauge, the electric control cabinet indicator lamp and the rotating speed is normal or not is determined through observation, and whether the powder of the transparent pipeline is conveyed or not is determined through observation. And (3) operating for 5 minutes after conveying is finished, turning off the power supply of each instrument, wherein the turn-off sequence of the power supply of each instrument is opposite to the start sequence of the step (4).
(6) After the equipment is stopped, the receiving hopper is beaten by a rubber hammer, so that all the powder in the receiving hopper enters each receiving cylinder, then each receiving cylinder control valve is closed, the powder is taken out, and the preparation process is finished.
Fig. 5 is a scanning electron microscope image of the tungsten powder obtained by the method, and as can be seen from fig. 5, the tungsten powder particles obtained by the method are all distributed in a dispersed manner, no agglomeration among particles exists, the particle sizes are not greatly different, and the particle size distribution of the powder is uniform. As can be seen by comparing fig. 5 with fig. 2, the particle size of the powder particles obtained in example 2 is significantly larger than that of the particles obtained in example 1.
FIG. 6 is a graph showing the particle size distribution of the tungsten powder obtained in example 2. As can be seen from FIG. 6, the particle size distribution of the tungsten powder obtained by the method of the present invention is a regular normal distribution, the D10 particle size of the powder is 7.826. Mu.m, the D90 is 23.400. Mu.m, and the particle size range of D10-D90 is narrowed to 15.574. Mu.m. The test powder had an average particle size of 7.63. Mu.m.
Example 3
(1) Putting tungsten powder which is a commercial raw material into a vacuum oven for vacuum drying, wherein the drying temperature is 150 ℃, the heat preservation time is 105min, and the vacuum degree is 10 -2 Pa。
(2) Adopting vertical fluidized bed type crushing and grading treatment, firstly setting each technological parameter, adjusting the air quantity of an induced draft fan and adjusting an airtight pressure gauge to enable the inlet pressure to be 0.15MPa; adjusting the valve of the blower to control the air quantity of the secondary air distribution to be 800m 3 /h; adjusting the feeder to 100kg/h; the classifier speed regulation value was set to 600r/min.
(3) Taking out the dried tungsten powder from the vacuum oven, feeding into a feeding cylinder (the time interval from taking out the powder to feeding into the feeding cylinder is not more than 30 minutes), covering a cover, and waiting for starting.
(4) The respective instruments were started up sequentially in the following order: (1) starting a classifier; (2) adjusting a classifier speed regulation table; (3) starting an induced draft fan; (4) starting a blower; (5) the feeder is started.
(5) And after all the components are started, the operation is started, whether the display of the classifying motor, the pressure gauge, the electric control cabinet indicator lamp and the rotating speed is normal or not is determined through observation, and whether the powder of the transparent pipeline is conveyed or not is determined through observation. And (3) operating for 5 minutes after conveying is finished, turning off the power supply of each instrument, wherein the turn-off sequence of the power supply of each instrument is opposite to the start sequence of the step (4).
(6) After the equipment is stopped, the receiving hopper is beaten by a rubber hammer, so that all the powder in the receiving hopper enters each receiving cylinder, then each receiving cylinder control valve is closed, the powder is taken out, and the preparation process is finished.
Fig. 7 is a scanning electron microscope image of the tungsten powder obtained in example 3 of the present invention, and it is clear from fig. 7 that the tungsten powder particles obtained by the method of the present invention are all dispersed, there is no agglomeration among particles, the particle size is not much different, and the particle size distribution of the powder is uniform. The powder particles of fig. 7 (obtained in example 3) were larger than the particles of fig. 3 (obtained in example 1) but slightly smaller than the particles of fig. 5 (obtained in example 2) compared to fig. 3 and 5.
FIG. 8 is a graph showing the particle size distribution of the tungsten powder obtained in example 3. As is clear from FIG. 8, the particle size distribution of the tungsten powder obtained by the method of the present invention is a regular normal distribution, the D10 particle size of the powder is 5.923. Mu.m, the D90 is 15.824. Mu.m, and the particle size range of D10-D90 is narrowed to 9.901. Mu.m, and is controlled to be within 10. Mu.m. The test powder had an average particle size of 6.02. Mu.m.
Example 4
(1) Putting commercial molybdenum powder into a vacuum oven for vacuum drying at 100deg.C for 120min with vacuum degree of 10 -2 Pa。
(2) Adopting vertical fluidized bed type crushing and grading treatment, firstly setting each technological parameter, adjusting the air quantity of an induced draft fan and adjusting an airtight pressure gauge to enable the inlet pressure to be 0.25MPa; adjusting the valve of the blower to control the air quantity of the secondary air distribution to be 500m 3 /h; adjusting the feeder to 40kg/h; the classifier speed regulation value was set at 800r/min.
(3) Taking the dried molybdenum powder out of the vacuum oven, feeding the molybdenum powder into a feeding cylinder (the time interval from the molybdenum powder taking out to the feeding cylinder is not more than 30 minutes), covering a cover, and waiting for starting.
(4) The respective instruments were started up sequentially in the following order: (1) starting a classifier; (2) adjusting a classifier speed regulation table; (3) starting an induced draft fan; (4) starting a blower; (5) the feeder is started.
(5) And after all the components are started, the operation is started, whether the display of the classifying motor, the pressure gauge, the electric control cabinet indicator lamp and the rotating speed is normal or not is determined through observation, and whether the powder of the transparent pipeline is conveyed or not is determined through observation. And (3) operating for 5 minutes after conveying is finished, and turning off the power supply of each instrument, wherein the turn-off sequence of the power supply of each instrument is opposite to the start sequence of the step (4).
(6) After the equipment is stopped, the receiving hopper is beaten by a rubber hammer, so that all the powder in the receiving hopper enters each receiving cylinder, then each receiving cylinder control valve is closed, and the powder is taken out, so that the whole preparation process is completed.
Fig. 9 shows a scanning electron microscope image of the original molybdenum powder used, and as can be seen from fig. 9, the original molybdenum powder particles have obvious agglomeration phenomenon and uneven particle size distribution. Fig. 10 shows the particle size distribution curve of the original molybdenum powder used, and it can be seen from fig. 10 that the curve is relatively large in the fine particle size section, the particle size distribution is uneven, and further, from the test data, the powder has a D10 particle size of 8.326 μm, a D90 of 36.523 μm, and a particle size range of D10-D90 of 28.197 μm.
Fig. 11 is a scanning electron microscope image of the molybdenum powder obtained by the above method, and it can be seen from fig. 11 that the molybdenum powder particles obtained by the method of the present invention are all dispersed, have no agglomeration among particles, have small particle size differences, and have uniform particle size distribution.
FIG. 12 is a graph showing the particle size distribution of the molybdenum powder obtained by the above method, and as can be seen from FIG. 12, the molybdenum particle size distribution obtained by the method of the present invention is a regular normal distribution, the D10 particle size of the powder is 2.654 μm, the D90 is 9.952 μm, and the particle size range of D10-D90 is narrowed to 7.298. Mu.m. The test powder had an average particle size of 3.17. Mu.m.
The commercial metal powder raw material has wide particle size distribution and agglomeration, and the D10-D90 particle size distribution width is up to more than 40 mu m, and the preparation method can control the D10-D90 particle size distribution width of the metal powder within 16 mu m.
Although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.