A method for sorting ultrafine diamond powder

Abstract

The present invention discloses a method for sorting ultrafine diamond micropowder, and relates to the field of diamond micropowder classification technology, including step one, preparing a dispersion liquid, adding a dispersant to heated water and stirring until dissolved; step two, adding a wetting agent to the dispersion liquid and stirring until dissolved; step three, adding ultrafine diamond micropowder to the step two mixed solution; step four, centrifugal sorting, correspondingly adjusting the centrifugal speed and time within different particle size ranges, repeating the centrifugation multiple times, and realizing the sorting of the ultrafine diamond micropowder in each particle size segment; step five, dehydration and drying, after all the ultrafine diamond micropowders located in different particle size segments are sorted, they are respectively subjected to one-time centrifugal dehydration, and dried, and the ultrafine diamond micropowder finished products of different particle size segments are obtained after removing all the water. The present invention has simple process and convenient operation, greatly saves manpower, material resources and energy consumption, significantly improves production efficiency and reduces production cost.

Description

Technical Field

[0001] The invention belongs to the technical field of diamond micropowder classification, and particularly relates to a method for sorting ultrafine diamond micropowder. Background Art

[0002] Diamond micropowder refers to diamond particles with a particle size of finer than 54 microns. It is a new type of superhard abrasive formed by special processing of synthetic diamond single crystals. It is an ideal raw material for grinding and polishing high-hardness materials such as cemented carbide, ceramics, gemstones, and optical glass. Diamond tools and components made from diamond particles are widely used in industries such as automobiles, machinery, electronics, aerospace, aviation, optical instruments, glass, ceramics, and petroleum. With the continuous development of technological products, its application areas are constantly expanding, and processing efficiency and precision have been improved by dozens or even hundreds of times. Materials that were difficult or even impossible to process in the past can now be processed at high speed, with high precision, and on a large scale.

[0003] However, the growing demand for diamond micropowders has led to ever-finer particle sizes, particularly for ultrafine diamond micropowders. Diamond particles with a particle size between 0.1 and 5 μm are typically used in the final stages of precision machining, with their use in precision polishing increasing by 20% annually. However, the limitations of diamond particle synthesis conditions lead to high production costs and high prices. Furthermore, before being used as an abrasive, the diamond particles must undergo crushing, shaping, purification, sorting, and drying, further increasing both production and operating costs.

[0004] Currently, the diamond sorting process includes dry sorting and wet sorting. Wet sorting is further divided into sedimentation sorting and centrifugal sorting according to the size of diamond particles. Centrifugal sorting is more suitable for sorting ultrafine diamond particles. However, the current ultrafine diamond powder centrifugal sorting technology still has a series of problems, resulting in low production efficiency.

[0005] The specific gravity of the diamond ultrafine powder slurry in the patent "A method for producing nano-scale diamond ultrafine powder (CN114853006A)" is only between 1-1.1, the powder addition ratio is low, and after centrifugation, only 1 / 2-3 / 4 of the upper suspension in the centrifuge cup is poured out, making it difficult to control the amount of liquid poured out of the suspension. The less the amount poured out, the more sorting times are required, and each centrifugation time is as long as 15-60 minutes, which greatly affects production efficiency. The mass of diamond micropowder in the patent "Diamond Micropowder Refining Classification Method (CN114870983A)" only accounts for 3-4% of the total mass of the diamond micropowder suspension, and the total mass of the centrifugal sorting is 10-20%. The number of times is no less than 3 times, and the overall production efficiency is low; the patent "A classification method for diamond micropowder (CN107262267B)" requires centrifugal dehydration 7-10 times, and the centrifugal separation slurry described in the patent "A preparation method of nano-scale diamond micropowder with narrow particle size distribution (CN106829954B)" and the patent "A preparation method of polycrystalline diamond abrasive with narrow distribution submicron size (CN102250582B)" has a mass ratio of diamond micropowder to water of (3-15):100 and (0.5-20):100, respectively. The ratio is relatively low, and the centrifugation time is as long as 5-120 minutes, resulting in low production efficiency.

[0006] How to achieve rapid and efficient sorting of ultrafine diamond powder, reduce production costs and usage costs, and improve production efficiency is an urgent problem to be solved. At the same time, this has very important practical significance for the rapid and healthy development of various application fields. Summary of the Invention

[0007] In view of the problems of low production efficiency, long production cycle and high production cost in the existing ultrafine diamond micropowder centrifugal sorting technology, which are mainly manifested in: (1) low slurry specific gravity and too small micropowder batch processing volume; (2) difficult to control the pouring volume after centrifugation, and difficult to operate in batch production; (3) small pouring volume and multiple sorting required for each particle size; (4) many dehydration times after centrifugation; (5) long centrifugation time, the present invention provides a sorting method for ultrafine diamond micropowder.

[0008] The solution adopted by the present invention to solve the technical problem is: a method for sorting ultrafine diamond powder, comprising the following steps:

[0009] Step 1, preparing a dispersion: adding water to a container and heating it, then adding a dispersant to the heated water and stirring until dissolved; the dispersant is composed of one or more of sodium polyacrylate, EDTMPS, FMES, HEDP, AA / AMPS, FMEE, AA-AMPS-HPA, AA-HPA-AMPS, PESA, sodium lignin, calcium lignin, sodium pyrophosphate, and ammonium citrate;

[0010] Step 2: Adding a wetting agent to the dispersion: Add a wetting agent to the dispersion obtained in step 1 and stir evenly until dissolved; the wetting agent is composed of one or more of methanol, ethanol, propylene glycol, acetone, propionaldehyde, Tween 20, ethyl formate, methyl acetate, ethyl acetate, ether, GSK-588, and butylene oxide;

[0011] Step 3: Add ultrafine diamond powder to the mixed solution of step 2: Continue to heat the mixed solution and add ultrafine diamond powder to the solution. Then continue to heat and stir the mixed solution for 25-30 minutes, and maintain the solution temperature in the range of 60-65°C.

[0012] Step 4: Centrifugal separation: The ultrafine diamond powder mixed solution obtained in step 3 is centrifuged. By detecting the particle size range of the ultrafine diamond powder, the centrifugal speed and time are adjusted accordingly. The suspension after centrifugation is poured out, and the powder precipitated at the bottom of the cup is re-formulated into a solution according to the above steps, and the centrifugal separation is continued. The centrifugation is repeated multiple times to achieve the separation of ultrafine diamond powder in each particle size range.

[0013] Step 5, dehydration and drying: After all the ultrafine diamond powders in different particle size segments in the above step 4 are sorted, they are centrifugally dehydrated and dried to remove all moisture to obtain finished ultrafine diamond powders in different particle size segments.

[0014] As a preferred technical solution of the present invention, the container in step 1 has the functions of stirring, heating and keeping warm at the same time.

[0015] As a preferred technical solution of the present invention, the water content in step 1 is 1-2 times the mass of the ultrafine diamond powder, and the amount of dispersant added is 0.05-0.5% of the mass of the ultrafine diamond powder.

[0016] As a preferred technical solution of the present invention, the amount of the wetting agent added in step 2 is 5-50% of the mass of the ultrafine diamond powder.

[0017] As a preferred technical solution of the present invention, in step three, the mixed solution containing the dispersant and the wetting agent is continued to be heated to 70° C., and ultrafine diamond powder is added to the solution.

[0018] As a preferred technical solution of the present invention, after the ultrafine diamond powder is added in step three, the specific gravity of the mixed solution reaches 1.3-1.5.

[0019] As a preferred technical solution of the present invention, the centrifugal speed and centrifugal time for centrifugal separation of the ultrafine diamond powder mixed solution in different particle size ranges in step 4 are set as follows:

[0020] A. The median value is within the range of 0.1±0.01μm, the rotation speed is 3000~3500rpm, and the time is 600~800s;

[0021] B. The median value is within the range of 0.2 ± 0.05 μm, the rotation speed is 2500~3000 rpm, and the time is 500~700 s;

[0022] C, median value 0.5 ± 0.05 μm, speed 1700-2100 rpm, time 400-600 s;

[0023] D, median value 0.75 ± 0.1 μm, speed 1500–1800 rpm, time 350–500 s;

[0024] E, median value 1.25 ± 0.15 μm, speed 1300–1600 rpm, time 250–400 s;

[0025] F, median value 1.75 ± 0.15 μm, speed 900–1200 rpm, time 200–300 s;

[0026] G, median value 2.25 ± 0.2 μm, rotation speed 700~900 rpm, time 150~250 s;

[0027] H, median value 2.75 ± 0.2 μm, speed 400–600 rpm, time 100–200 s;

[0028] I, median value 3.25 ± 0.25 μm, rotation speed 200~400 rpm, time 60~120 s.

[0029] As a preferred technical solution of the present invention, the centrifugal separation of each particle size segment in step 4 is repeated 2-3 times.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) As the particle size of diamond micropowder becomes finer, its surface area becomes larger and larger, so that the diamond micropowder becomes more and more likely to agglomerate. Especially when the particle size of the micropowder is below 3 μm, the dispersing ability of general dispersants (such as sodium silicate) can no longer meet the dispersion requirements. The dispersant prepared by the present invention can disperse ultrafine micropowders and has a higher dispersing ability, further improving the dispersion effect.

[0032] (2) The wetting agent prepared by the present invention can effectively reduce the surface tension of water, improve the wettability between diamond micropowders, and thus improve the surface activity of diamond micropowders. In addition, the density of the wetting agent prepared by the present invention is smaller than that of water, which is used to reduce the density of the aqueous solution, increase the sinking speed of the diamond micropowder, and thus improve the sorting efficiency of the diamond micropowder;

[0033] (3) The present invention adopts a dispersant and wetting agent with higher dispersibility and increases the solution temperature, so that the ultrafine diamond powder obtains a better dispersion effect and the solution viscosity is reduced, thereby increasing the amount of powder separated by each centrifugal separation, reducing the number of separations, shortening the separation time, and improving the separation efficiency;

[0034] (4) The increase in the specific gravity of the solution greatly increases the batch processing capacity of ultrafine diamond powder. Moreover, after centrifugation, the suspension in the centrifugal cup can be poured out in one go, which is easy to operate and greatly improves production efficiency. After centrifugal separation, only one centrifugal dehydration is required, which greatly reduces the number of dehydration cycles. The present invention has a simple process and is easy to operate, which greatly saves manpower, material resources and energy consumption, significantly improves production efficiency, reduces production costs, and is conducive to industrialized mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the finished particle size distribution diagram of 0.11μm ultrafine diamond powder;

[0036] Figure 2 This is the finished particle size distribution diagram of 0.23μm ultrafine diamond powder;

[0037] Figure 3 This is the finished particle size distribution diagram of 0.49μm ultrafine diamond powder;

[0038] Figure 4 This is the finished particle size distribution diagram of 0.77μm ultrafine diamond powder;

[0039] Figure 5 This is the finished particle size distribution diagram of 1.23μm ultrafine diamond powder;

[0040] Figure 6 This is the finished particle size distribution diagram of 1.74μm ultrafine diamond powder;

[0041] Figure 7 This is the finished particle size distribution diagram of 2.26μm ultrafine diamond powder;

[0042] Figure 8 This is the finished particle size distribution diagram of 2.75μm ultrafine diamond powder;

[0043] Figure 9 This is the particle size distribution diagram of the finished product of 3.23μm ultrafine diamond powder;

[0044] Figure 10 This is the particle size distribution diagram of the finished product of 3.77μm ultrafine diamond powder;

[0045] Figure 11 1 is an overall flow chart of the method of the present invention. Implementation Method

[0046] The present invention will be further described below with reference to the accompanying drawings and examples.

[0047] See also Figure 1-11 In view of the problems of low production efficiency, long production cycle and high production cost in the current ultrafine diamond powder sorting process, the present invention provides a method for sorting ultrafine diamond powder.

[0048] Example 1: This example provides a method for sorting ultrafine diamond powder, comprising the following steps:

[0049] Step 1: Prepare dispersion:

[0050] Water is added to a container equipped with stirring, heating, and heat-insulating functions and heated. The water content is twice the mass of the ultrafine diamond powder. A dispersant is added to the heated water and slowly stirred until it is completely dissolved in the water. The amount of dispersant added is 0.38% of the mass of the ultrafine diamond powder. As the particle size of the diamond powder becomes finer, its surface area becomes larger. Therefore, as the surface area increases, the diamond powder is more likely to agglomerate. Especially when the particle size is below 3 μm, the dispersing ability of conventional dispersants (such as sodium silicate) no longer meets the dispersion requirements. Therefore, this embodiment uses a dispersant formulated from sodium polyacrylate, EDTMPS, FMES, AA-AMPS-HPA, AA-HPA-AMPS, PESA, sodium lignin, calcium lignin, and sodium pyrophosphate to provide it with higher dispersing ability and achieve a better dispersion effect.

[0051] Step 2: Add a wetting agent to the dispersion obtained in step 1:

[0052] After the dispersant in step 1 is completely dissolved to obtain a dispersion, a wetting agent is added to the dispersion and slowly stirred until it is completely dissolved and dispersed in water. The amount of wetting agent added is 50% of the mass of the ultrafine diamond powder. Since the surface activity decreases with the increase of the surface energy of the diamond powder, the diamond powder becomes more difficult to disperse. Therefore, in order to increase the surface activity and make the diamond powder easier to disperse, this embodiment uses a wetting agent prepared from methanol, ethanol, propylene glycol, ethyl formate, methyl acetate, ethyl acetate, ether, and GSK-588 to reduce the surface tension of water, improve the wettability between water and diamond powder, and thus improve the surface activity of the diamond powder.

[0053] Step 3: Add ultrafine diamond powder to the mixed solution of step 2:

[0054] The mixed solution obtained in step 2 is heated to 70°C. After that, the stirring speed of the solution is increased while ensuring that the liquid does not splash. Ultrafine diamond powder is slowly added to the solution. After the diamond is added, heating and stirring are continued for 25 minutes to ensure that the ultrafine diamond powder is completely and evenly wetted and dispersed in the water. The solution temperature is maintained within the range of 60-65°C. After the ultrafine diamond powder is added in this step, the specific gravity of the mixed solution reaches 1.3;

[0055] Step 4: Centrifugal separation:

[0056] After the ultrafine diamond powder mixed solution obtained in step 3 is stirred, the stirred liquid is immediately divided into centrifugal cups, and the particle size is detected to determine the particle size range of the ultrafine diamond powder. The centrifugal speed and centrifugal time of the ultrafine diamond powder in different particle size segments are adjusted in a targeted manner during centrifugal separation, thereby achieving the separation of ultrafine diamond powder in each particle size segment. In this embodiment, ultrafine diamond powder of a certain particle size value is selected in each particle size range for centrifugal separation, specifically including:

[0057] (1) Centrifugal separation of ultrafine diamond powder mixed solution with a median value of 0.11 μm was performed. The centrifugal speed was set at 3000~3500 rpm and the time was 600~800 s. After centrifugation, all the suspension in the cup was poured out. The powder precipitated at the bottom of the cup was taken out and re-formulated into liquid according to the above steps 1-3. The centrifugal speed and time were adjusted again. After centrifugation, all the flowing liquid in the cup was still poured out. The powder precipitated at the bottom of the cup can be taken out and re-formulated into liquid according to the above steps and sorted again. Repeating this process twice can completely separate the ultrafine diamond powder. The finished particle size distribution of 0.11 μm ultrafine diamond powder is as follows: Figure 1 As shown;

[0058] (2) Centrifugal separation of the mixed solution of ultrafine diamond powder with a median value of 0.23 μm was performed. The centrifugal speed was set at 2500~3000 rpm and the time was 500~700 s. After centrifugation, all the suspension in the cup was poured out, the powder precipitated at the bottom of the cup was taken out and re-formulated into liquid according to the above steps 1-3. The centrifugal speed and time were adjusted again. After centrifugation, all the flowing liquid in the cup was still poured out. The powder precipitated at the bottom of the cup can be taken out and re-formulated into liquid according to the above steps and sorted again. Repeating this process twice can completely separate the ultrafine diamond powder. The finished particle size distribution of the 0.23 μm ultrafine diamond powder is as follows: Figure 2 As shown;

[0059] (3) Centrifugal separation of the ultrafine diamond powder mixed solution with a median value of 0.49 μm was performed. The centrifugal speed was set at 1700~2100 rpm and the time was 400~600 s. After centrifugation, all the suspension in the cup was poured out, the powder precipitated at the bottom of the cup was taken out and re-formulated into liquid according to the above steps 1-3. The centrifugal speed and time were adjusted again. After centrifugation, all the flowing liquid in the cup was still poured out. The powder precipitated at the bottom of the cup can be taken out and re-formulated into liquid according to the above steps and sorted again. Repeating this process twice can completely separate the ultrafine diamond powder. The finished particle size distribution of the 0.49 μm ultrafine diamond powder is as follows: Figure 3 As shown;

[0060] (4) Centrifugal separation of the mixed solution of ultrafine diamond powder with a median value of 0.77 μm was performed. The centrifugal speed was set at 1500~1800 rpm and the time was 350~500 s. After centrifugation, all the suspension in the cup was poured out, the powder precipitated at the bottom of the cup was taken out and re-formulated into liquid according to the above steps 1-3. The centrifugal speed and time were adjusted again. After centrifugation, all the flowing liquid in the cup was still poured out. The powder precipitated at the bottom of the cup can be taken out and re-formulated into liquid according to the above steps and sorted again. Repeat 3 times to completely sort out the ultrafine diamond powder. The finished particle size distribution of the 0.77 μm ultrafine diamond powder is as follows: Figure 4 As shown;

[0061] (5) Centrifugal separation of the mixed solution of ultrafine diamond powder with a median value of 1.23 μm was performed. The centrifugal speed was set at 1300~1600 rpm and the time was 250~400 s. After centrifugation, all the suspension in the cup was poured out, the powder precipitated at the bottom of the cup was taken out and re-formulated into liquid according to the above steps 1-3. The centrifugal speed and time were adjusted again. After centrifugation, all the flowing liquid in the cup was still poured out. The powder precipitated at the bottom of the cup can be taken out and re-formulated into liquid according to the above steps and sorted again. Repeat 3 times to completely sort out the ultrafine diamond powder. The finished particle size distribution of the 1.23 μm ultrafine diamond powder is as follows: Figure 5 As shown;

[0062] (6) Centrifugal separation of the mixed solution of ultrafine diamond micropowder with a median value of 1.74 μm was performed. The centrifugal speed was set at 900~1200 rpm and the time was 200~300 s. After centrifugation, all the suspension in the cup was poured out, the micropowder precipitated at the bottom of the cup was taken out and re-formulated into liquid according to the above steps 1-3. The centrifugal speed and time were adjusted again. After centrifugation, all the flowing liquid in the cup was still poured out. The micropowder precipitated at the bottom of the cup can be taken out and re-formulated into liquid according to the above steps and sorted again. Repeat 3 times to completely sort out the ultrafine diamond micropowder. The finished particle size distribution of the 1.74 μm ultrafine diamond micropowder is as follows: Figure 6 As shown;

[0063] (7) The mixed solution of ultrafine diamond powder with a median value of 2.26 μm was centrifuged and sorted. The centrifugal speed was set at 700~900 rpm and the time was 150~250 s. After centrifugation, all the suspension in the cup was poured out, the powder precipitated at the bottom of the cup was taken out and re-formed into liquid according to the above steps 1-3. The centrifugal speed and time were adjusted again. After centrifugation, all the flowing liquid in the cup was still poured out. The powder precipitated at the bottom of the cup can be taken out and re-formed into liquid according to the above steps and sorted again. Repeat 3 times to completely sort out the ultrafine diamond powder. The finished particle size distribution of the 2.26 μm ultrafine diamond powder is as follows: Figure 7 As shown;

[0064] (8) Centrifugal separation of the mixed solution of ultrafine diamond powder with a median of 2.75 μm was performed. The centrifugal speed was set at 400~600 rpm and the time was 100~200 s. After centrifugation, all the suspension in the cup was poured out, the powder precipitated at the bottom of the cup was taken out and re-formed into liquid according to the above steps 1-3. The centrifugal speed and time were adjusted again. After centrifugation, all the flowing liquid in the cup was still poured out. The powder precipitated at the bottom of the cup can be taken out and re-formed into liquid according to the above steps and sorted again. Repeat 3 times to completely sort out the ultrafine diamond powder. The finished particle size distribution of the 2.75 μm ultrafine diamond powder is as follows: Figure 8 As shown;

[0065] (9) Centrifugal separation is performed on the mixed solution of ultrafine diamond powder with a median of 3.23 μm. The centrifugal speed is set at 200~400 rpm and the time is 60~120 s. After centrifugation, all the suspension in the cup is poured out, the powder precipitated at the bottom of the cup is taken out and re-formulated into liquid according to the above steps 1-3. The centrifugal speed and time are adjusted again. After centrifugation, all the flowing liquid in the cup is still poured out. The powder precipitated at the bottom of the cup can be taken out and re-formulated into liquid according to the above steps and sorted again. Repeat 3 times to completely sort out the ultrafine diamond powder. The finished particle size distribution of the 3.23 μm ultrafine diamond powder is as follows: Figure 9 As shown;

[0066] (10) The mixed solution of ultrafine diamond micropowder with a median of 3.77 μm was centrifuged and sorted. The centrifugal speed was set at 200~400 rpm and the time was 60~120 s. After centrifugation, all the suspension in the cup was poured out. The micropowder precipitated at the bottom of the cup was taken out and re-formed into liquid according to the above steps 1-3. The centrifugal speed and time were adjusted again. After centrifugation, all the flowing liquid in the cup was poured out. The micropowder precipitated at the bottom of the cup can be taken out and re-formed into liquid according to the above steps and sorted again. Repeat 3 times to completely sort out the ultrafine diamond micropowder. The finished particle size distribution of 3.77 μm ultrafine diamond micropowder is as follows: Figure 10 As shown;

[0067] Step 5: Dehydration and drying

[0068] After the above steps have completed the sorting of all the ultrafine diamond micropowders in different particle size segments, the liquid poured out after centrifugation is poured into a centrifugal cup for one-time centrifugal dehydration. Finally, the ultrafine diamond micropowder after centrifugal dehydration is taken out from the centrifugal cup and placed in an oven for drying. After removing all the water, the finished ultrafine diamond micropowders in different particle size segments can be obtained. The present invention adopts a dispersant and a wetting agent with high dispersibility and increases the solution temperature, so that the ultrafine diamond micropowder obtains a better dispersion effect and the solution viscosity is reduced, thereby increasing the amount of micropowder sorted out by each centrifugation, reducing the number of sorting times, shortening the sorting time, and improving the sorting efficiency. The present invention has a simple process and is easy to operate, greatly saving manpower, material resources and energy consumption, significantly improving production efficiency, reducing production costs, and being conducive to industrialized mass production. Example

[0069] This embodiment provides a method for sorting ultrafine diamond powder, comprising the following steps:

[0070] Step 1: Prepare dispersion:

[0071] Add water to a container with stirring, heating, and heat preservation functions and heat it, wherein the water content is 1.3 times the mass of the ultrafine diamond powder. Add a dispersant to the heating water and slowly stir until it is completely dissolved in the water. The amount of dispersant added is 0.5% of the mass of the ultrafine diamond powder. The dispersant used in this embodiment is composed of AA / AMPS, FMEE, AA-AMPS-HPA, AA-HPA-AMPS, PESA, sodium lignin, calcium lignin, sodium pyrophosphate, and ammonium citrate, so that it has a high dispersibility to obtain a better dispersion effect.

[0072] Step 2: Add a wetting agent to the dispersion obtained in step 1:

[0073] After the dispersant in step 1 is completely dissolved to obtain a dispersion, a wetting agent is added to the dispersion and slowly stirred until it is completely dissolved and dispersed in water. The amount of wetting agent added is 35% of the mass of the ultrafine diamond powder. The wetting agent used in this embodiment is prepared from methanol, ethanol, propylene glycol, acetone, propionaldehyde, Tween 20, GSK-588, and butylene oxide to reduce the surface tension of water, improve the wettability between water and diamond powder, and thus improve the surface activity of the diamond powder;

[0074] Step 3: Add ultrafine diamond powder to the mixed solution of step 2:

[0075] The mixed solution obtained in step 2 is heated to 70°C. After that, the stirring speed of the solution is increased while ensuring that the liquid does not splash. Ultrafine diamond powder is slowly added to the solution. After the diamond is added, heating and stirring are continued for 30 minutes to ensure that the ultrafine diamond powder is completely and evenly wetted and dispersed in the water. The solution temperature is maintained within the range of 60-65°C. After the ultrafine diamond powder is added in this step, the specific gravity of the mixed solution reaches 1.4;

[0076] Step 4: Centrifugal separation

[0077] After the ultrafine diamond powder mixed solution obtained in step 3 is stirred, the stirred liquid is immediately divided into centrifugal cups, and the particle size range of the ultrafine diamond powder is determined by performing a particle size test on the liquid. Then, the centrifugal speed and centrifugal time for centrifugal separation of ultrafine diamond powders in different particle size ranges are adjusted accordingly. Ultrafine diamond powders of the same particle size segment can be completely separated out by at most three times, thereby achieving separation of ultrafine diamond powders in various particle size segments.

[0078] Step 5: Dehydration and drying

[0079] After the ultrafine diamond micropowders in different particle size segments are completely sorted in the above steps, the liquid poured out after centrifugation is poured into the centrifugal cup for one-time centrifugal dehydration. Finally, the ultrafine diamond micropowder after centrifugal dehydration is taken out from the centrifugal cup and placed in an oven for drying. After all the water is removed, the finished ultrafine diamond micropowders in different particle size segments can be obtained. Example

[0080] This embodiment provides a method for sorting ultrafine diamond powder, comprising the following steps:

[0081] Step 1: Prepare dispersion:

[0082] Add water to a container with stirring, heating and heat preservation functions and heat it, wherein the water content is 1 times the mass of the ultrafine diamond powder, add a dispersant to the heating water and slowly stir until it is completely dissolved in the water, wherein the amount of dispersant added is 0.2% of the mass of the ultrafine diamond powder, and the dispersant used in this embodiment is composed of sodium polyacrylate, EDTMPS, FMES, sodium lignin, calcium lignin, sodium pyrophosphate, and ammonium citrate, so that it has a high dispersing ability to obtain a better dispersion effect;

[0083] Step 2: Add a wetting agent to the dispersion obtained in step 1:

[0084] After the dispersant in step 1 is completely dissolved to obtain a dispersion, a wetting agent is added to the dispersion and slowly stirred until it is completely dissolved and dispersed in water. The amount of wetting agent added is 5% of the mass of the ultrafine diamond powder. The wetting agent used in this embodiment is prepared from ethanol, propylene glycol, acetone, propionaldehyde, Tween 20, ethyl formate, GSK-588, and butylene oxide to reduce the surface tension of water, improve the wettability between water and diamond powder, and thus improve the surface activity of the diamond powder;

[0085] Step 3: Add ultrafine diamond powder to the mixed solution of step 2:

[0086] The mixed solution obtained in step 2 is heated to 70°C. After that, the stirring speed of the solution is increased while ensuring that the liquid does not splash. Ultrafine diamond powder is slowly added to the solution. After the diamond is added, heating and stirring are continued for 25 minutes to ensure that the ultrafine diamond powder is completely and evenly wetted and dispersed in the water. The solution temperature is maintained within the range of 60-65°C. After the ultrafine diamond powder is added in this step, the specific gravity of the mixed solution reaches 1.5;

[0087] Step 4: Centrifugal separation

[0088] After the ultrafine diamond powder mixed solution obtained in step 3 is stirred, the stirred liquid is immediately divided into centrifugal cups, and the particle size range of the ultrafine diamond powder is determined by performing a particle size test on the liquid. Then, the centrifugal speed and centrifugal time for centrifugal separation of ultrafine diamond powders in different particle size ranges are adjusted accordingly. Ultrafine diamond powders of the same particle size segment can be completely separated out by at most three times, thereby achieving separation of ultrafine diamond powders in various particle size segments.

[0089] Step 5: Dehydration and drying

[0090] After the ultrafine diamond micropowders in different particle size segments are completely sorted in the above steps, the liquid poured out after centrifugation is poured into the centrifugal cup for one-time centrifugal dehydration. Finally, the ultrafine diamond micropowder after centrifugal dehydration is taken out from the centrifugal cup and placed in an oven for drying. After all the water is removed, the finished ultrafine diamond micropowders in different particle size segments can be obtained. Example

[0091] This embodiment provides a method for sorting ultrafine diamond powder, comprising the following steps:

[0092] Step 1: Prepare dispersion:

[0093] Add water to a container with stirring, heating, and heat preservation functions and heat it, wherein the water content is 1.5 times the mass of the ultrafine diamond powder. Add a dispersant to the heated water and slowly stir until it is completely dissolved in the water. The amount of dispersant added is 0.05% of the mass of the ultrafine diamond powder. The dispersant used in this embodiment is composed of sodium polyacrylate, EDTMPS, FMES, HEDP, AA / AMPS, FMEE, AA-AMPS-HPA, AA-HPA-AMPS, PESA, sodium lignin, calcium lignin, sodium pyrophosphate, and ammonium citrate, so that it has a high dispersibility to obtain a better dispersion effect.

[0094] Step 2: Add a wetting agent to the dispersion obtained in step 1:

[0095] After the dispersant in step 1 is completely dissolved to obtain a dispersion, a wetting agent is added to the dispersion and slowly stirred until it is completely dissolved and dispersed in water. The amount of wetting agent added is 15% of the mass of the ultrafine diamond powder. The wetting agent used in this embodiment is prepared from methanol, ethanol, propylene glycol, acetone, propionaldehyde, Tween 20, ethyl formate, methyl acetate, ethyl acetate, ether, GSK-588, and butylene oxide to reduce the surface tension of water, improve the wettability between water and diamond powder, and thus improve the surface activity of the diamond powder;

[0096] Step 3: Add ultrafine diamond powder to the mixed solution of step 2:

[0097] The mixed solution obtained in step 2 is heated to 70°C. After that, the stirring speed of the solution is increased while ensuring that the liquid does not splash. Ultrafine diamond powder is slowly added to the solution. After the diamond is added, heating and stirring are continued for 30 minutes to ensure that the ultrafine diamond powder is completely and evenly wetted and dispersed in the water. The solution temperature is maintained within the range of 60-65°C. After the ultrafine diamond powder is added in this step, the specific gravity of the mixed solution reaches 1.4;

[0098] Step 4: Centrifugal separation

[0099] After the ultrafine diamond powder mixed solution obtained in step 3 is stirred, the stirred liquid is immediately divided into centrifugal cups, and the particle size range of the ultrafine diamond powder is determined by performing a particle size test on the liquid. Then, the centrifugal speed and centrifugal time for centrifugal separation of ultrafine diamond powders in different particle size ranges are adjusted accordingly. Ultrafine diamond powders of the same particle size segment can be completely separated out by at most three times, thereby achieving separation of ultrafine diamond powders in various particle size segments.

[0100] Step 5: Dehydration and drying

[0101] After the ultrafine diamond micropowders in different particle size segments are completely sorted in the above steps, the liquid poured out after centrifugation is poured into the centrifugal cup for one-time centrifugal dehydration. Finally, the ultrafine diamond micropowder after centrifugal dehydration is taken out from the centrifugal cup and placed in an oven for drying. After all the water is removed, the finished ultrafine diamond micropowders in different particle size segments can be obtained.

[0102] The above description is only a preferred embodiment of the present invention and does not limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for sorting ultrafine diamond powder, characterized by: The following steps are involved: Step 1: Prepare a dispersion: Add water to a container and heat it, add a dispersant to the heated water and stir until dissolved; the dispersant is prepared from sodium polyacrylate, EDTMPS, FMES, AA-AMPS-HPA, AA-HPA-AMPS, PESA, sodium lignin, calcium lignin, sodium pyrophosphate, and ammonium citrate; the water content is 1-2 times the mass of the ultrafine diamond powder, and the amount of dispersant added is 0.05-0.5% of the mass of the ultrafine diamond powder; Step 2: Adding a wetting agent to the dispersion: Add a wetting agent to the dispersion obtained in step 1 and stir evenly until dissolved to obtain a mixed solution; the wetting agent is composed of one or more of methanol, ethanol, propylene glycol, acetone, propionaldehyde, Tween 20, ethyl formate, methyl acetate, ethyl acetate, ether, GSK-588, and butylene oxide; the amount of the wetting agent added is 5-50% of the mass of the ultrafine diamond powder; Step 3: Adding ultrafine diamond powder to the mixed solution of step 2: Continue heating the mixed solution to 70°C, and add ultrafine diamond powder to the mixed solution until the specific gravity of the mixed solution reaches 1.3-1.5 after adding the ultrafine diamond powder. Then continue heating and stirring the mixed solution for 25-30 minutes, and maintain the solution temperature in the range of 60-65°C; Step 4: Centrifugal separation: The ultrafine diamond powder mixed solution obtained in step 3 is centrifuged. By detecting the particle size range of the ultrafine diamond powder, the centrifugal speed and time are adjusted accordingly. The suspension after centrifugation is poured out, and the powder precipitated at the bottom of the cup is re-formed into a solution according to steps 1 to 3 above, and centrifugal separation is continued. The centrifugation is repeated multiple times to achieve the separation of ultrafine diamond powder in each particle size range. Step 5, dehydration and drying: After all the ultrafine diamond powders in different particle size segments in the above step 4 are sorted, they are centrifugally dehydrated and dried to remove all moisture to obtain finished ultrafine diamond powders in different particle size segments.

2. The method for separating ultrafine diamond powder according to claim 1, wherein: The container in step 1 has the functions of stirring, heating and keeping warm at the same time.

3. The method for separating ultrafine diamond powder according to claim 1, wherein: In the fourth step, the centrifugal speed and centrifugal time for centrifugal separation of the ultrafine diamond powder mixed solution in different particle size ranges are set as follows: A. The median value is within the range of 0.1±0.01μm, the rotation speed is 3000~3500rpm, and the time is 600~800s; B. The median value is within the range of 0.2 ± 0.05 μm, the rotation speed is 2500~3000 rpm, and the time is 500~700 s; C, median value 0.5 ± 0.05 μm, speed 1700-2100 rpm, time 400-600 s; D, median value 0.75 ± 0.1 μm, speed 1500–1800 rpm, time 350–500 s; E, median value 1.25 ± 0.15 μm, speed 1300–1600 rpm, time 250–400 s; F, median value 1.75 ± 0.15 μm, speed 900–1200 rpm, time 200–300 s; G, median value 2.25 ± 0.2 μm, rotation speed 700~900 rpm, time 150~250 s; H, median value 2.75 ± 0.2 μm, speed 400–600 rpm, time 100–200 s; I, median value 3.25 ± 0.25 μm, rotation speed 200~400 rpm, time 60~120 s.

4. The method for separating ultrafine diamond powder according to claim 1, wherein: The centrifugal separation of each particle size segment in step 4 is repeated 2-3 times.

Images