Preparation method of beryllium powder for beryllium rolled plate ingot

Abstract

The invention discloses a preparation method of beryllium powder for a beryllium rolled plate ingot, and belongs to the technical field of beryllium metals.The preparation method comprises the steps that under the closed condition, a 5-30 A motor current is adopted, beryllium chippings are subjected to disc smashing, and flaky crude beryllium powder with the particle size being 15-30 microns is obtained; under a closed condition, adopting a set airflow impact parameter to impact and crush the sheet-shaped coarse beryllium powder for 20-35 minutes, then detecting the particle size of the beryllium powder, and carrying out time-sharing adjustment on the frequency of a grading wheel in the airflow impact parameter according to the detection result of the particle size of the beryllium powder until the particle size of the beryllium powder meets a preset range of the particle size of the sheet-shaped fine beryllium powder, so as to obtain the sheet-shaped fine beryllium powder. Flaky fine beryllium powder is obtained; and S3, the flaky fine beryllium powder is sequentially subjected to acid pickling, water washing, alcohol washing, vacuum drying and powder screening. The beryllium powder is flaky powder, is stable in particle size, good in consistency and high in production efficiency, and meets the rolling performance requirements of rolled plate ingots.

Description

Technical Field

[0001] The invention belongs to the technical field of beryllium metal, and in particular relates to a method for preparing beryllium powder for beryllium rolled plate ingots. Background Art

[0002] Beryllium metal has become an indispensable material in important fields such as nuclear industry, aerospace, etc. due to its unique properties such as low density, high melting point, high specific strength, large seed scattering area, etc. To obtain high-performance beryllium materials, we must start from two aspects: one is the preparation of high-quality beryllium powder, and the other is the use of advanced forming and consolidation processes.

[0003] The existing powder preparation methods mainly include mechanical method and physical and chemical method. The mechanical method is to mechanically crush the raw materials. The physical and chemical method is to obtain beryllium powder by changing the chemical composition or aggregation state of the raw materials through chemical or physical effects. Due to the brittleness of beryllium metal, the mechanical method can quickly prepare beryllium powder in batches. The existing beryllium powder preparation method is mainly mechanical method.

[0004] The mechanical methods mainly include disc mill crushing and powder making method and air flow impact crushing and powder making method. The beryllium powder prepared by disc mill crushing and powder making method has high requirements on powder morphology and particle size. Therefore, in the production process, the disc gap must be adjusted to a small size to prepare finer beryllium powder. However, if the disc gap is too small during production, if larger beryllium debris particles enter, it is very easy to cause the disc to stop production. Therefore, the production is difficult and the production efficiency is low. The beryllium powder prepared by air flow impact crushing and powder making method has a polygonal block morphology. The rolling performance of the rolled plate ingot prepared by beryllium powder of this morphology is poor. Cracks, slag, and peeling will appear when rolling to about 2mm, which cannot meet the existing rolling performance requirements for rolled plate ingots. Contents of invention

[0005] The object of the present invention is to provide a method for preparing beryllium powder for beryllium rolled plate ingots. The beryllium powder prepared by the method is flaky powder with stable particle size, good consistency and high production efficiency, and meets the rolling performance requirements of rolled plate ingots.

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

[0007] A method for preparing beryllium powder for beryllium rolled plate ingots, the preparation method comprising:

[0008] Step S1, under closed conditions, using a motor current of 5 to 30 A to perform disc crushing on beryllium debris to obtain flaky coarse beryllium powder with a particle size of 15 to 30 μm;

[0009] Step S2, under closed conditions, using set airflow impact parameters, the flaky coarse beryllium powder is airflow impact crushed for 20 to 35 minutes, then the particle size of the beryllium powder is detected, and then according to the beryllium powder particle size detection result, the frequency of the grading wheel in the airflow impact parameter is adjusted in time until the particle size of the beryllium powder meets the predetermined range of the particle size of the flaky fine beryllium powder, thereby obtaining the flaky fine beryllium powder;

[0010] In step S2, the specific process of the time-sharing adjustment is:

[0011] When the beryllium powder particle size detection result is greater than the upper limit value of the predetermined range, the frequency of the classifying wheel in the airflow impact parameter is increased by 1 to 2 Hz for each micron that the beryllium powder particle size detection result exceeds the upper limit value, and the airflow impact crushing is continued, and the beryllium powder particle size and the frequency of the classifying wheel are increased in real time until the beryllium powder particle size meets the predetermined range;

[0012] Step S3, sequentially acid-washing, water-washing, alcohol-washing, vacuum-drying and sieving the flaky fine beryllium powder.

[0013] Furthermore, in the step S1, the beryllium scraps are beryllium ingots, with a beryllium content greater than 99.5% and an iron content greater than 500 ppm;

[0014] The volume of the beryllium debris is 3-7 mm*1-5 mm*0.3-0.7 mm.

[0015] Further, in the step S1, the motor current is 10-20A;

[0016] The time for crushing the disc is 1 to 2 hours.

[0017] Further, in the step S2, the airflow impact parameters include air compressor air source pressure, impact gas pressure, classifier wheel frequency and induced draft fan frequency;

[0018] The air source pressure, impact gas pressure, classifying wheel frequency and induced draft fan frequency of the air compressor are 0.5-4MPa, 0.4-3.9MPa, 5-50Hz and 10-80Hz respectively.

[0019] Furthermore, in step S3, the specific process of pickling includes:

[0020] The flake fine beryllium powder is soaked in water at a ratio of 1 to 5 L of water per kg of flake fine beryllium powder, and stirred evenly to obtain a uniform powder liquid; then, nitric acid with a concentration of 65% to 68% is added to the uniform powder liquid at a volume mass ratio of 0.1 to 1.5 L / kg, and after stirring for 10 to 24 hours, the powder liquid is drained.

[0021] Furthermore, in step S3, during the water washing process, the volume mass ratio of water to the flaky fine beryllium powder after the powder liquid is drained is 45 to 55 L / kg.

[0022] Furthermore, in step S3, the number of times of water washing is 2 to 4 times.

[0023] Furthermore, in step S3, the specific process of the alcohol washing is as follows:

[0024] According to the volume-to-mass ratio of 3 to 7 L / kg, anhydrous ethanol with a concentration greater than 98% is added to the washed flaky fine beryllium powder, and then stirred and the powder liquid is drained.

[0025] Furthermore, in step S3, the process conditions of the vacuum drying are:

[0026] The vacuum degree is -50 to -100 kPa, the temperature is 50 to 90°C, and the time is 10 to 24 hours.

[0027] Furthermore, in step S3, a closed double-layer vibrating screen with a mesh size of 100 to 375 is used to screen the powder.

[0028] The predetermined range in the present invention is 6 to 11 μm.

[0029] In summary, the technical solution of the present invention has the following technical effects:

[0030] 1. The present invention uses disc crushing and air flow impact crushing, and uses time-sharing to adjust the frequency of the grading wheel during the air flow impact crushing process, so as to ensure that the beryllium powder is in the form of flaky powder with high consistency of particle size, controllable particle size, small fluctuation and uniformity, and at the same time has high production efficiency, and the daily production capacity can reach more than 20 kg, which is suitable for large-scale industrial production; the beryllium rolled plate ingot produced by the beryllium powder of the present invention has good rolling performance, and production verification shows that it can roll beryllium sheets of 0.5 to 1 mm, and the surface of the beryllium sheets has no cracks, no peeling, and no slag falling. During rolling, it shows good rolling performance, which meets the production needs of beryllium sheets.

[0031] 2. The beryllium powder of the present invention is produced in a closed environment in the equipment, which reduces the harm to the operators and the production environment, and at the same time avoids the loss of beryllium powder caused by being exhausted, thereby improving the utilization rate of raw materials. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described. 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.

[0033] Embodiment 1:

[0034] 1. Under closed conditions, use a disc crusher to grind powder, with the motor current controlled at 5A, and crush the beryllium debris disc with a size of 3mm*1mm*0.3mm, a beryllium content of 99.8%, and an iron content of 600ppm for 1 hour to obtain a flaky coarse beryllium powder with a particle size of 30μm;

[0035] 2. Under closed conditions, when the machine is turned on, the air source pressure of the air compressor is set to 0.5MPa, the impact gas pressure is set to 0.4MPa, the frequency of the classifying wheel is set to 38Hz, and the frequency of the induced draft fan is set to 80Hz. The flaky coarse beryllium powder is crushed by air flow impact. During the air flow impact crushing process, the produced beryllium powder is sampled every 20 minutes to detect its particle size. When the beryllium powder particle size test result is 17μm, which exceeds the upper limit of the preset range of 11μm by 6μm, the frequency of the classifying wheel is increased by 6Hz, and the air flow impact crushing is continued. The beryllium powder particle size and the frequency of the classifying wheel are detected in real time and adjusted upward until a beryllium powder particle size of 11μm is obtained.

[0036] 3. Soak the prepared flaky fine beryllium powder in 1L pure water per kg of beryllium powder and stir evenly. After stirring evenly, pour it into the pickling stirring tank, add 66% nitric acid at a ratio of 1.5L nitric acid per kg of beryllium powder, and stir the reaction time for pickling for 24 hours. Then, lay the suction filter bag in the pickling filter tank, pour the powder liquid after pickling and stirring into the filter bag, and turn on the suction pump to drain the powder liquid.

[0037] 4. After draining, add water at a ratio of 45L of water per kg of the dried powder, and stir evenly. Turn on the filter pump again to drain the powder, and add pure water for washing 4 times. After the last pure water washing, add 98.5% anhydrous ethanol to the washed flaky fine beryllium powder at a volume mass ratio of 7L / kg, then stir and drain the powder again.

[0038] 5. Pour the beryllium powder that has been dried after adding alcohol into a vacuum oven, turn on the vacuum pump to pump the vacuum degree of the oven to -50kpa, set the oven temperature to 50℃, and dry it for 10 hours.

[0039] 6. Use a closed double-layer vibrating screen to sieve the powder, with the upper screen having a 100-mesh size and the lower screen having a 150-mesh size, to sieve the dried beryllium powder.

[0040] The beryllium powder prepared in this embodiment is sintered into a plate ingot at a sintering temperature of 1200° C. and a holding time of 4 hours. After completion, the plate ingot is rolled into a 1 mm beryllium sheet with no cracks, peeling or slag on the surface. The rolling performance meets the production requirements of beryllium sheets.

[0041] Embodiment 2:

[0042] 1. Under closed conditions, use a disc mill to grind powder, with the motor current controlled at 30A, and grind the beryllium debris disc with a size of 7mm*5mm*0.7mm, a beryllium content of 99.8%, and an iron content of 550ppm for 2 hours to obtain a flaky coarse beryllium powder with a particle size of 15μm;

[0043] 2. Under closed conditions, when the machine is started, the air source pressure of the air compressor is set to 4MPa, the impact gas pressure is set to 3.9MPa, the frequency of the classifying wheel is set to 5Hz, and the frequency of the induced draft fan is set to 10Hz. The flaky coarse beryllium powder is crushed by air flow impact. During the air flow impact crushing process, the produced beryllium powder is sampled every 35 minutes to detect its particle size. When the beryllium powder particle size test result is 14μm, which exceeds the upper limit of the preset range of 11μm by 3μm, the frequency of the classifying wheel is increased by 6Hz, and the air flow impact crushing is continued. The beryllium powder particle size and the frequency of the classifying wheel are detected in real time and adjusted upward until a beryllium powder particle size of 6μm is obtained.

[0044] 3. Soak the prepared flaky fine beryllium powder in 5L pure water per kg of beryllium powder and stir evenly. After stirring evenly, pour it into the pickling stirring tank, add 68% nitric acid at a ratio of 0.1L nitric acid per kg of beryllium powder, and stir the reaction time for pickling for 10 hours. Then, place the suction filter bag in the pickling suction tank, pour the powder liquid after pickling and stirring into the filter bag, and turn on the suction pump to drain the powder liquid.

[0045] 4. After draining, add water at a ratio of 55L of water per kg of the dried powder, and stir evenly. Turn on the filter pump again to drain the powder, and add pure water for washing twice. After the last pure water washing, add 98.5% anhydrous ethanol to the washed flaky fine beryllium powder at a volume mass ratio of 3L / kg, then stir and drain the powder again.

[0046] 5. Pour the beryllium powder that has been dried after adding alcohol into a vacuum oven, turn on the vacuum pump to pump the vacuum degree of the oven to -100kpa, set the oven temperature to 90℃, and dry it for 24 hours.

[0047] 6. Use a closed double-layer vibrating screen to sieve the powder, with the upper screen of 300 mesh and the lower screen of 375 mesh to sieve the dried beryllium powder.

[0048] The beryllium powder prepared in this embodiment is sintered into a plate ingot at a sintering temperature of 1200° C. and a holding time of 4 hours. After completion, the plate ingot is rolled into a 0.5 mm beryllium sheet with no cracks, peeling or slag on the surface. The rolling performance meets the production requirements of beryllium sheets.

[0049] Embodiment 3:

[0050] 1. Under closed conditions, use a disc crusher to grind powder, the motor current is controlled at 20A, and the beryllium debris disc with a size of 5mm*3mm*0.5mm, a beryllium content of 99.8%, and an iron content of 550ppm is crushed for 1.5 hours to obtain flaky coarse beryllium powder with a particle size of 20μm.

[0051] 2. Under closed conditions, when the machine is started, the air source pressure of the air compressor is set to 2.5MPa, the impact gas pressure is set to 2.0MPa, the frequency of the classifying wheel is set to 35Hz, and the frequency of the induced draft fan is set to 50Hz. The flaky coarse beryllium powder is crushed by air flow impact. During the air flow impact crushing process, the produced beryllium powder is sampled every 30 minutes to detect its particle size. When the beryllium powder particle size test result is 15μm, which exceeds the upper limit of the preset range of 11μm by 4μm, the frequency of the classifying wheel is increased by 6Hz, and the air flow impact crushing is continued. The beryllium powder particle size and the frequency of the classifying wheel are detected in real time and adjusted upward until a beryllium powder particle size of 8μm is obtained.

[0052] 3. Soak the prepared flaky fine beryllium powder in 3L pure water per kg of beryllium powder and stir evenly. After stirring evenly, pour it into the pickling stirring tank, add 65% nitric acid at a ratio of 1L nitric acid per kg of beryllium powder, and stir the reaction time for pickling for 16 hours. Then, lay the suction filter bag in the pickling filter tank, pour the powder liquid after pickling and stirring into the filter bag, and turn on the suction pump to drain the powder liquid.

[0053] 4. After draining, add water at a ratio of 50L of water per kg of the dried powder, and stir evenly. Turn on the filter pump again to drain the powder, and add pure water for washing 3 times. After the last pure water washing, add 98.5% anhydrous ethanol to the washed flaky fine beryllium powder at a volume mass ratio of 5L / kg, then stir and drain the powder again.

[0054] 5. Pour the beryllium powder that has been dried after adding alcohol into a vacuum oven, turn on the vacuum pump to pump the vacuum degree of the oven to -80kPa, set the oven temperature to 70°C, and dry it for 16 hours.

[0055] 6. Use a closed double-layer vibrating screen to sieve the powder, with the upper screen having a mesh size of 250 and the lower screen having a mesh size of 320 to sieve the dried beryllium powder.

[0056] The beryllium powder prepared in this embodiment is sintered into a plate ingot at a sintering temperature of 1200° C. and a holding time of 4 hours. After completion, the plate ingot is rolled into a 0.7 mm beryllium sheet with no cracks, peeling or slag on the surface. The rolling performance meets the production requirements of beryllium sheets.

[0057] Please note that the technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. The above embodiments only express several implementation methods of the present application, and their descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several variations and improvements can be made, which all belong to the scope of protection of the present application. Therefore, the scope of protection of the patent in this application shall be based on the attached claims.

Claims

1. A method for preparing beryllium powder for beryllium rolled plate ingots, characterized in that: The preparation method comprises: Step S1, under closed conditions, using a motor current of 5 to 30 A to perform disc crushing on beryllium debris to obtain flaky coarse beryllium powder with a particle size of 15 to 30 μm; Step S2, under closed conditions, using set airflow impact parameters, the flaky coarse beryllium powder is airflow impact crushed for 20 to 35 minutes, then the particle size of the beryllium powder is detected, and then according to the beryllium powder particle size detection result, the frequency of the grading wheel in the airflow impact parameter is adjusted in time until the particle size of the beryllium powder meets the predetermined range of the particle size of the flaky fine beryllium powder, thereby obtaining the flaky fine beryllium powder; In step S2, the specific process of the time-sharing adjustment is: When the beryllium powder particle size detection result is greater than the upper limit value of the predetermined range, the frequency of the classifying wheel in the airflow impact parameter is increased by 1 to 2 Hz for each micron that the beryllium powder particle size detection result exceeds the upper limit value, and the airflow impact crushing is continued, and the beryllium powder particle size and the frequency of the classifying wheel are increased in real time until the beryllium powder particle size meets the predetermined range; Step S3, sequentially acid-washing, water-washing, alcohol-washing, vacuum-drying and sieving the flaky fine beryllium powder.

2. The preparation method according to claim 1, characterized in that: In the step S1, the beryllium scraps are beryllium ingots, with a beryllium content greater than 99.5% and an iron content greater than 500 ppm; The volume of the beryllium debris is 3-7 mm*1-5 mm*0.3-0.7 mm.

3. The preparation method according to claim 2, characterized in that: In the step S1, the motor current is 5 to 30A; The disk crushing time is 1 to 2 hours.

4. The preparation method according to any one of claims 1 to 3, characterized in that: In step S2, the airflow impact parameters include air compressor air source pressure, impact gas pressure, classifier wheel frequency and induced draft fan frequency; The air source pressure, impact gas pressure, classifying wheel frequency and induced draft fan frequency of the air compressor are 0.5-4MPa, 0.4-3.9MPa, 5-50Hz and 10-80Hz respectively.

5. The preparation method according to claim 4, characterized in that: In step S3, the specific process of pickling includes: The flake fine beryllium powder is soaked in water at a ratio of 1 to 5 L of water per kg of flake fine beryllium powder, and stirred evenly to obtain a uniform powder liquid; then, nitric acid with a concentration of 65% to 68% is added to the uniform powder liquid at a volume mass ratio of 0.1 to 1.5 L / kg, and after stirring for 10 to 24 hours, the powder liquid is drained.

6. The preparation method according to claim 5, characterized in that: In step S3, during the water washing process, the volume mass ratio of water to the flaky fine beryllium powder after the powder liquid is drained is 45-55 L / kg.

7. The preparation method according to claim 6, characterized in that: In step S3, the water washing is performed 2 to 4 times.

8. The preparation method according to claim 7, characterized in that: In step S3, the specific process of the alcohol washing is: According to the volume-to-mass ratio of 3 to 7 L / kg, anhydrous ethanol with a concentration greater than 98% is added to the washed flaky fine beryllium powder, and then stirred and the powder liquid is drained.

9. The preparation method according to claim 8, characterized in that: In step S3, the process conditions of the vacuum drying are: The vacuum degree is -50 to -100 kPa, the temperature is 50 to 90°C, and the time is 10 to 24 hours.

10. The preparation method according to claim 9, characterized in that: In the step S3, a closed double-layer vibrating screen with a mesh size of 100 to 375 is used to screen the powder.