Method for separating nano material by supergravity and supergravity separator

Abstract

The invention provides a method for separating nano materials through supergravity and a supergravity separator, and belongs to the technical field of nano material preparation, and the method comprises the following steps: 1) starting the supergravity separator to reach a set rotating speed; (2) feeding a feed liquid into a feed port of the separator, and feeding the feed liquid into a separation area from an inlet of an outer spiral flow channel; (3) most of the feed liquid tangentially flows along the outer spiral flow channel, particles in the feed liquid settle to the surface of the inclined flow channel and slide outwards, a small part of the feed liquid penetrates through a slit between the outer spiral flow channel and the top plate step by step to generate a shearing and mixing effect on the sliding particles, and high-concentration suspension liquid is formed and enters a collecting tank; (4) the feed liquid leaves the separation area, enters a backflow area along an inlet of the inner spiral flow channel and is sprayed out from a discharge port; and (5) quickly depositing the high-concentration suspension liquid into a collecting tank, and enabling the clear liquid to enter a backflow area from a backflow hole channel. According to the invention, the separation efficiency is obviously improved, and various nano materials can be simply, quickly and efficiently separated in a low-cost and high-quality manner.

Description

Technical Field

[0001] The invention relates to the technical field of nano material preparation, and in particular to a method for ultra-gravity separation of nano materials and an ultra-gravity separator. Background Art

[0002] Graphene preparation methods are divided into exfoliation (top-down) and chemical vapor deposition (bottom-up). Graphene products with fewer defects can generally be obtained through physical exfoliation. Since each exfoliation method has certain limitations, in order to improve the exfoliation efficiency, the exfoliation process can be divided into two stages: the first stage is from graphite slurry to intermediate suspension, and the second stage is from intermediate suspension to graphene sol. Different exfoliation methods are used in each stage. Exfoliation is to mix and disperse graphite in the gas phase or liquid phase in the form of graphene, which is a mixing process. Using the different sedimentation rates between slurry, suspension and sol, the three are separated step by step, which is a separation process. Mixing is combining two into one, and separation is dividing one into two. Although the two processes are contradictory, they complement each other and can be perfectly coupled together to form a process cycle. The cycle can significantly increase the yield of graphene.

[0003] Supergravity technology is a new technology for strengthening multiphase flow transfer and reaction processes. Due to its wide applicability and advantages that traditional equipment does not have, such as small size, light weight, low energy consumption, easy operation, easy maintenance, safety, reliability, flexibility and better adaptability to the environment, supergravity technology has broad commercial application prospects in industrial fields such as environmental protection, materials, biology, and chemical industry. The basic principle of supergravity engineering technology is to utilize the unique flow behavior of multiphase flow systems under supergravity field conditions to strengthen the relative speed and mutual contact between phases, thereby achieving efficient momentum, mass and heat transfer processes. The way to form a supergravity field is to use a motor to rotate the entire device or components to form a centrifugal field.

[0004] The Chinese patent "A method and device for continuous supergravity separation of two-dimensional nanomaterials" (Announcement No.: CN108993784 B) discloses a method for purifying graphene. The method and device for continuous supergravity separation of two-dimensional nanomaterials designed according to the U-tube principle continuously injects graphite slurry containing graphene into the central feed port of the supergravity separator, and the feed liquid is thrown outward along the U-tube channel. The high-concentration graphite slurry is thrown to the bottom of the U-tube and sprayed from the outermost upper nozzle. The low-concentration graphene solution flows in the U-tube against the direction of the supergravity field and sprays from the lower nozzle on the inside. A large number of experimental results show that due to the long sedimentation distance, small sedimentation area and large sedimentation resistance of this method, the graphene separation is slow, the efficiency is low, and the separation is not thorough. The most fundamental reason is that this process is a pure separation process without the assistance of a mixing process, so the efficiency is low. Summary of the invention

[0005] The purpose of the present invention is to provide a method for ultra-gravity separation of nanomaterials and an ultra-gravity separator, which greatly improves the separation efficiency with the assistance of a mixing process, and can achieve simple, rapid, efficient, energy-saving, low-cost, large-scale, and high-quality separation of various nanomaterials.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] In a first aspect, a method for separating nanomaterials by ultra-gravity is provided, characterized in that the method comprises the following steps:

[0008] 1) The speed of the ultra-gravity separator is controlled by a frequency regulator. Set the frequency of the frequency regulator and start the ultra-gravity separator. The ultra-gravity separator accelerates and rotates to the set speed. The intensity of the ultra-gravity field is proportional to the square of the speed.

[0009] 2) The feed liquid is injected into the feed port of the high-speed rotating stator part and enters the separation zone along the entrances of multiple external spiral flow channels.

[0010] 3) In the separation zone, there are two flow modes of the feed liquid: tangential flow and radial flow. In the tangential flow, most of the feed liquid flows along the outer spiral flow channel. During the tangential flow, the suspended or sol particles in the feed liquid slowly settle to the inclined surface of the outer spiral flow channel, and the particles slide outward along the outer spiral flow channel; in the radial flow, a small part of the feed liquid quickly passes through the slit between the top plate and the inclined surface of the outer spiral flow channel, and at the same time, the particles sliding there are sheared and mixed into a high-concentration feed liquid. The high-concentration feed liquid continues to settle along the top plate to the next level of slits, and then outward in turn until it settles to the outermost collection tank.

[0011] 4) When the tangential flow reaches the outermost layer of the outer spiral flow channel, the feed liquid continues to enter the reflux zone downward along the tangential direction. The reflux zone contains multiple inner spiral flow channels. The feed liquid rotates along the inner spiral flow channels and refluxes to the rotor part discharge port, and is sprayed into the stator cavity of the ultra-gravity separator from the rotor part discharge port, and then flows out from the first discharge port of the stator cavity.

[0012] 5) When the radial flow enters the collecting tank, the high-concentration suspension quickly settles to the outermost side of the collecting tank, and the clear liquid enters the reflux zone along the reflux channel. When the volume of solid particles collected in the collecting tank reaches a certain value, stop feeding and shut down the machine. After the ultra-gravity separator stops completely and all the liquid in the ultra-gravity separator flows out, open the cover of the stator part and the top plate of the rotor part, take out the collecting tank, scrape off all the wet filter cakes with a scraper, put the collecting tank back into the rotor part, buckle the top plate of the rotor part and the cover of the stator part, and prepare to start the next round of centrifugal separation operation.

[0013] Furthermore, in the step 1), the supergravity field generated by the supergravity separator gradually increases from the center to the outermost side, and the maximum supergravity field intensity in the supergravity separator is controlled at 2000-4000g.

[0014] Furthermore, in the step 3), the slip angle of the outer spiral flow channel is 40-55°, the sedimentation distance of the suspended or sol-state particles in the outer spiral flow channel is 15-30 mm, the width of the inclined surface of the outer spiral flow channel is not less than 60 mm, and the width of the slit between the inclined surface of the outer spiral flow channel and the top plate is 0.5-1.5 mm.

[0015] Furthermore, in the step 4), the flow cross-section of the inner spiral flow channel is a rectangular plane with a constant height and a continuously narrowing width, and the number of the inner spiral flow channels and the number of the outer spiral flow channels are equal, and are not less than 4.

[0016] Furthermore, in the step 5), the ratio of the downward flow cross section of the outermost tangential flow of the outer spiral flow channel to the flow cross section of the reflow channel is 10-20.

[0017] Furthermore, in step 5), the maximum sedimentation volume of the collecting tank is 60% of the volume of the collecting tank. When this volume is reached, the separation process should be stopped and the material should be discharged.

[0018] In a second aspect, a super gravity separator is characterized by:

[0019] The ultra-gravity separator comprises a motor, a stator part and a rotor part. The motor is arranged at the bottom of the ultra-gravity separator, the stator part is arranged at the top of the motor, and the rotor part is arranged inside the stator part.

[0020] The rotor part includes a collecting trough, a reflux channel, a rotor part discharge port, a top plate and a turntable base. The top plate and the turntable base are tightly fastened together to form a rotor inner cavity and a rotor outer cavity. The rotor inner cavity is divided into a separation area and a reflux area by a fixed disc. The front side of the disc is engraved with an outer spiral flow channel, and the back side of the disc is engraved with an inner spiral flow channel. A collecting trough is fixedly arranged inside the rotor outer cavity. The collecting trough is equipped with a handle. The collecting trough and the rotor inner cavity form a liquid circuit through the reflux channel. The rotor part discharge port is arranged at the inner edge of the spiral flow channel in the inner cavity.

[0021] The stator part is a closed cylinder, comprising a feed port, a first discharge port and a second discharge port. The stator part is divided into a stator inner cavity and a stator outer cavity by a circular baffle. The feed port is arranged at the top center of the stator part, the first discharge port is arranged at the bottom of the stator inner cavity, and the second discharge port is arranged at the bottom of the stator outer cavity.

[0022] Advantages of the present invention:

[0023] 1. The method for separating nanoparticles by ultra-gravity of the present invention has the advantages of high ultra-gravity field intensity, large sedimentation area, short sedimentation distance, small sedimentation resistance, etc. By coupling the separation and mixing processes together, the separation efficiency is significantly improved, and a simple, fast, efficient, energy-saving, low-cost, large-scale, high-quality process of separating various nanomaterials is achieved.

[0024] 2. The ultra-gravity separator described in the present invention has many advantages such as simple structure, easy processing, easy operation, easy cleaning, easy scale-up, and easy automated continuous production.

[0025] 3. In practical applications, the method and device of the present invention can be used to separate various nanoparticles from suspended state to sol state by adjusting the rotation speed, liquid flow rate, or changing the disc size, and has the advantages of large operational flexibility and strong adjustability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the super gravity separator in the present invention;

[0027] Figure 2 A schematic diagram of an outer spiral line formed by the intersection of the outer spiral flow channel and the front face of the disk in the present invention;

[0028] Figure 3 It is a schematic diagram of the inner spiral line formed by the intersection of the inner spiral flow channel and the reverse side of the disk in the present invention;

[0029] Figure 4 A simplified process flow diagram of the present invention for preparing an intermediate suspension by coupling a supergravity stripping machine with a supergravity separator;

[0030] In the figure: 1. Motor,

[0031] 2. Stator part, 2-1, feed port, 2-2, first discharge port, 2-3, second discharge port,

[0032] 3. Rotor part, 3-1. Separation zone, 3-2. Reflux zone, 3-3. Collection tank, 3-4. Reflux channel, 3-5. Discharge port of rotor part, 3-6. Top plate, 3-7. Turntable base,

[0033] 4. Ultra-gravity separator,

[0034] 5. Super gravity stripping machine,

[0035] 6. Graphite slurry,

[0036] 7. Intermediate suspension,

[0037] 8. Colorless clear liquid. DETAILED DESCRIPTION

[0038] 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 will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention.

[0039] like Figure 1-Figure 4 As shown, a method for separating nanomaterials by ultra-gravity, the method comprising the following steps:

[0040] 1) The rotation speed of the ultra-gravity separator 4 is controlled by a frequency modulator. The frequency of the frequency modulator is set and the ultra-gravity separator 4 is started. The ultra-gravity separator 4 is intermittent. The ultra-gravity separator 4 accelerates and rotates to reach the set rotation speed. The intensity of the ultra-gravity field is proportional to the square of the rotation speed.

[0041] 2) The feed liquid is injected into the feed port 2-1 of the high-speed rotating stator part 2 and enters the separation zone 3-1 along the entrances of multiple external spiral flow channels.

[0042] 3) In the separation zone 3-1, the feed liquid has two flow modes: tangential flow and radial flow. The tangential flow flows along the direction of the outer spiral flow channel. The characteristics of the outer spiral flow channel are large sedimentation area, short sedimentation distance, and the flow direction of the feed liquid is almost perpendicular to the sedimentation direction of the material. The sedimentation process is basically unaffected by the flow of the feed liquid, and a rapid sedimentation process of the particles can be achieved. During the tangential flow process, the suspended or sol particles in the feed liquid slowly settle to the inclined surface of the outer spiral flow channel under the action of the supergravity field. The inclination angle between the outer spiral flow channel and the separator shaft is called the slip angle. The particles slide outward along the outer spiral flow channel. Since the concentration of the settled particles in the tangential flow is gradually reduced, the tangential flow belongs to the separation process. During the radial flow process, there is a very narrow slit between the inclined surface of the outer spiral flow channel and the top plate 3-6. Due to the high pressure difference on both sides of the slit, the liquid flow rate in the slit is very fast, and the particles that slide here can be mixed into a high-concentration liquid through shearing and pass through the slit, and then settle along the top plate to the next level of slits, and then outward in turn until they settle in the outermost collection tank 3-3. During the tangential flow process, the concentration of the settled particles will gradually decrease, which is a separation process. During the radial flow process, the concentration of the settled particles will increase step by step, which is a mixing process. The higher the concentration of the settled particles, the faster the sedimentation rate.

[0043] 4) When the tangential flow reaches the outermost layer of the outer spiral flow channel, the concentration of particles in the feed liquid drops to the minimum, and the feed liquid continues to move downward along the tangent direction into the reflux zone 3-2. The reflux zone 3-2 contains multiple inner spiral flow channels, which are characterized by a short reflux distance, a large flow cross-section, and a small reflux resistance. From a top-down perspective, the direction of the outer spiral flow is consistent with that of the inner spiral flow, and both are opposite to the rotation direction of the ultra-gravity separator 4. This not only increases the driving force for the feed liquid to flow outward, but also reduces the resistance to the reflux of the feed liquid. The feed liquid rotates and flows back along the inner spiral flow channel to the rotor partial discharge port 3-5, and is sprayed into the stator inner cavity of the ultra-gravity separator 4 from the rotor partial discharge port 3-5, and then flows out from the first discharge port 2-2 of the stator inner cavity.

[0044] 5) After the radial flow enters the collecting tank 3-3, the high-concentration suspension quickly settles to the outermost side of the collecting tank 3-3, and the clear liquid enters the recirculation zone 3-2 along the recirculation channel 3-4. The flow ratio between the tangential flow and the radial flow at the outermost side of the outer spiral flow channel is determined by the flow cross-section size of the recirculation channel. When the volume of solid particles collected in the collecting tank 3-3 reaches a certain value, stop feeding, shut down the machine, wait until the ultra-gravity separator 4 stops completely and all the liquid in the ultra-gravity separator 4 flows out, open the cover plate of the stator part 2 and the top plate 3-6 of the rotor part 3, take out the collecting tank 3-3, scrape off all the wet filter cakes with a scraper, put the collecting tank 3-3 back into the rotor part 3, buckle the top plate 3-6 of the rotor part 3 and the cover plate of the stator part 2, and prepare to start the next round of centrifugal separation operation.

[0045] The ultra-gravity separation method proposed in the present invention is only applicable to the separation of suspended or sol particles, and is not applicable to the separation of pure solid particles.

[0046] As a preferred embodiment of the present invention, the supergravity field generated by the supergravity separator 4 in step 1) gradually increases from the center to the outermost side, and the maximum supergravity field strength in the supergravity separator 4 is controlled at 2000-4000g.

[0047] As a preferred embodiment of the present invention, in the step 3), the slip angle of the outer spiral flow channel is 40-55°, the sedimentation distance of the suspended or sol-state particles in the outer spiral flow channel is 15-30 mm, the width of the inclined surface of the outer spiral flow channel is not less than 60 mm, and the width of the slit between the inclined surface of the outer spiral flow channel and the top plate is 0.5-1.5 mm.

[0048] As a preferred embodiment of the present invention, the flow cross-section of the inner spiral flow channel in step 4) is a rectangular plane with a constant height and a continuously narrowing width, and the number of the inner spiral flow channels and the outer spiral flow channels are equal, and are not less than 4.

[0049] As a preferred embodiment of the present invention, in the step 5), the ratio of the downward flow cross section of the outermost tangential flow of the outer spiral flow channel to the flow cross section of the reflow channel is 10-20.

[0050] As a preferred embodiment of the present invention, the maximum sedimentation volume of the collecting tank 3-3 in step 5) is 60% of the volume of the collecting tank 3-3. When this volume is reached, the separation process should be stopped and unloaded.

[0051] The ultra-gravity separation method proposed in the present invention can achieve perfect coupling between efficient separation and efficient mixing, with separation as the main method and mixing as the auxiliary method, and its separation efficiency is much higher than that of traditional nanoparticle separation methods.

[0052] Based on the above-mentioned method of ultra-gravity separation of nanomaterials, the present invention also proposes an ultra-gravity separator 4, including a motor 1, a stator part 2 and a rotor part 3, wherein the motor 1 is arranged at the bottom of the ultra-gravity separator 4, the stator part 2 is arranged at the top of the motor 1, and the rotor part 3 is arranged inside the stator part 2.

[0053] The rotor part 3 includes a collecting trough 3-3, a reflux channel 3-4, a rotor part discharge port 3-5, a top plate 3-6 and a turntable base 3-7. The top plate 3-6 and the turntable base 3-7 are tightly fastened together to form a rotor inner cavity and a rotor outer cavity. The rotor inner cavity is divided into a separation area 3-1 and a reflux area 3-2 by a fixed disc. The front side of the disc is engraved with an outer spiral flow channel, and the back side of the disc is engraved with an inner spiral flow channel. A collecting trough 3-3 is fixedly arranged inside the rotor outer cavity. The collecting trough 3-3 is equipped with a handle, and the collecting trough 3-3 can be taken out of the outer cavity. The collecting trough 3-3 and the rotor inner cavity form a liquid circuit through the reflux channel 3-4. The rotor part discharge port 3-5 is arranged at the inner edge of the spiral flow channel in the inner cavity, and the rotor part discharge port 3-5 is arranged near the rotating shaft.

[0054] The stator part 2 is a closed cylinder, comprising a feed port 2-1, a first discharge port 2-2 and a second discharge port 2-3. The stator part 2 is divided into a stator inner cavity and a stator outer cavity by a circular baffle. The feed port 2-1 is arranged at the center position of the cover plate of the stator part 2, the first discharge port 2-2 is arranged at the bottom of the stator inner cavity, and the second discharge port 2-3 is arranged at the bottom of the stator outer cavity.

[0055] The liquid thrown out from the rotor part outlet 3-5 is blocked in the stator inner cavity by the circular baffle, and only a very small amount of droplets will be thrown into the stator outer cavity. If the super gravity separator 4 leaks, the liquid flowing out of the stator outer cavity will increase significantly. This efficient intermittent super gravity separator has the advantages of easy automatic operation and control, easy scale-up, and easy industrial application.

[0056] Embodiment 1:

[0057] An isopropanol aqueous solution was used as a stripping solvent and graphite was used as a raw material, and an intermediate precipitate was prepared by ultra-gravity coupling technology.

[0058] The characteristics of the super gravity stripping machine 5 are stripping as the main function and separation as the auxiliary function, and it can be operated in a continuous cycle. Figure 1-Figure 4 As shown, in this embodiment, a small supergravity stripping machine 5 and two identical small supergravity separators 4 form a small test circulation system, and the two supergravity separators 4 are operated in rotation. The circulation flow rate of the circulation system is 24L / min, the total volume of the supergravity separator 4 is 8L, and the average residence time of the feed liquid in the supergravity separator 4 is 20s. The number of inner and outer spiral flow channels is 8. The slip angle of the outer spiral flow channel is 40 degrees, the sedimentation distance of the intermediate suspension 7 in the outer spiral flow channel is 30 mm, the length of the inclined surface of the outer spiral flow channel is 60 mm, the width of the slit between the inclined surface of the outer spiral flow channel and the top plate 3-6 is 1.5 mm, and the ratio of the downward flow section of the outermost tangential flow of the outer spiral flow channel to the flow section of the reflux channel 3-4 is 20. The volume of the collecting tank 3-3 is 3L, and when the volume of the intermediate sediment in the collecting tank 3-3 reaches 60%, it is 1.8L, and about 540g of intermediate precipitation can be obtained. During the entire operation cycle, the concentration of the intermediate suspension 7 entering the super gravity separator 4 is about 150 mg / L. After the colorless clear liquid 8 flows out of the super gravity separator 4, it flows back to the super gravity stripping machine 5 through the pipeline. The feed liquid circulates in an "∞" shape between the super gravity stripping machine 5 and the super gravity separator 4. The circulating feed liquid undergoes three different stages of changes: graphite slurry 6 → intermediate suspension 7 → colorless clear liquid 8. During this process, the flow rate of the feed liquid remains unchanged. After 150 minutes, the volume of the intermediate precipitate in the collecting tank 3-3 reaches 60%, and the two super gravity separators 4 are rotated. After the replaced ultra-gravity separator 4 has completely stopped and all the liquid in the ultra-gravity separator 4 has flowed out, open the cover plate of the stator part 2 and the top plate 3-6 of the rotor part 3, take out the collecting tank 3-3, scrape off all the intermediate precipitated wet filter cake with a scraper, then put the collecting tank 3-3 back into the ultra-gravity separator 4, buckle the top plate 3-6 of the rotor part 3 and the cover plate of the stator part 2, and wait for the next rotation operation.

[0059] The speed of the motor 1 of the supergravity separator 4 is controlled by a frequency regulator, which is connected to an external 380V AC power supply. The frequency regulator is set to 65Hz, and the corresponding maximum supergravity field strength is 2000g. Before the two supergravity separators 4 start to rotate, the frequency regulator is turned on first. After the supergravity separator 4 starts to idle and gradually reaches the set frequency of 65Hz, the frequency regulator displays the current flow at this time. After the current stabilizes, the rotation begins. After the feed liquid with a flow rate of 24L / min enters the idling supergravity separator 4, the load of the supergravity separator 4 increases rapidly, and the current also increases rapidly. When the feed liquid flows out of the outlet of the supergravity separator 4 stably, the current also stabilizes. There is an operating upper limit for the flow rate of the feed liquid entering the supergravity separator 4. If the flow rate exceeds this upper limit, the supergravity separator 4 will vibrate violently, resulting in unstable operation and may even cause serious accidents. Therefore, the flow rate of the circulating feed liquid needs to be monitored in real time to ensure that the flow fluctuation range is significantly lower than the operating upper limit.

[0060] The scraped wet filter cake of the intermediate precipitate is mixed with the stripping solvent again and dispersed into a uniformly distributed suspension in a crusher with a concentration of about 600 mg / L. A new stripping method is used to cyclically strip the intermediate suspension 7, which is not within the scope of the present invention. Each time the intermediate suspension is stripped, a separation operation is required, and the separation operation is divided into two steps: the first step is to separate the intermediate suspension 7 from the graphene sol in the form of a precipitate (Example 2); the second step is to separate the graphene sol from the colorless clear liquid 8 in the form of a precipitate (Example 3).

[0061] Example 2

[0062] In this embodiment, two small-sized ultra-gravity separators 4 are used to perform the separation operation between the intermediate suspension 7 and the graphene sol in rotation. The structures of the two ultra-gravity separators 4 used in this embodiment and in Example 1 are basically the same, except that: first, the width of the slit between the inclined surface of the outer spiral flow channel and the top plate 3-6 is 1.0 mm; second, the ratio of the downward flow cross-section of the outermost tangential flow of the outer spiral flow channel to the flow cross-section of the reflux channel 3-4 is 15. The feed flow rate is controlled at 12L / min, and the average residence time of the feed liquid in the ultra-gravity separator 4 is 40s. The frequency of the frequency modulator that controls the speed of the motor 1 is set at 80Hz, and the corresponding maximum ultra-gravity field strength is 3000g. When the intermediate deposition volume in the collecting tank 3-3 reaches 1.8L, about 450g of the intermediate can be obtained. The concentration of the intermediate suspension 7 entering the ultra-gravity separator 4 remains basically unchanged. After about 60 minutes, the volume of the sediment in the collecting tank 3-3 reaches 1.8L, and the two ultra-gravity separators 4 are rotated. The intermediate wet filter cake in the collecting tank 3-3 is scraped off with a scraper, mixed with the stripping solvent again, and dispersed into a uniformly distributed suspension with a concentration of about 600mg / L in a crusher, and the stripping operation is performed again. The feed liquid sprayed from the rotor part discharge port 3-5 is a light black graphene sol with a concentration of about 40mg / L.

[0063] Example 3

[0064] In the present embodiment, two small-sized supergravity separators 4 different from those in Example 1 are operated in parallel to realize the separation process between graphene sol and colorless clear liquid. The internal structures of the two supergravity separators 4 are exactly the same. When separating graphene sol, the frequency of the frequency modulator controlling the rotation speed of the motor 1 is set at 92Hz, and the corresponding maximum supergravity field strength reaches 4000g. The total volume of each supergravity separator 4 is 7.5L, the number of inner and outer spiral flow channels is 4, the slip angle of the outer spiral flow channel is 55 degrees, the sedimentation distance of the graphene sol in the outer spiral flow channel is 15 mm, the inclined surface length of the outer spiral flow channel is 80 mm, the width of the slit between the inclined surface of the outer spiral flow channel and the top plate 3-6 is 0.5 mm, and the ratio of the downward flow cross section of the outermost tangential flow of the outer spiral flow channel to the flow cross section of the return channel 3-4 is 10. The volume of the collecting tank 3-3 is still 3L. When the sedimentation volume of the graphene sol in the collecting tank 3-3 reaches 1.8L, about 200g of graphene sol can be obtained. During operation, the feed flow rate of each ultra-gravity separator 4 is controlled at 7.5L / min, the average residence time of the feed liquid in the ultra-gravity separator 4 is about 60s, the graphene sol feed concentration is about 40mg / L, and the sediment volume in the collecting tank 3-3 reaches 1.8L after about 11h, and the machine is stopped for discharge.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can still adjust the technical solutions described in the above embodiments or replace some of the technical features by equivalents. Therefore, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A method for separating nanomaterials by ultra-gravity, characterized in that: The method comprises the following steps: 1) The rotation speed of the ultra-gravity separator (4) is controlled by a frequency modulator. The frequency of the frequency modulator is set, and the ultra-gravity separator (4) is started. The ultra-gravity separator (4) is accelerated to rotate to reach the set rotation speed. The intensity of the ultra-gravity field is proportional to the square of the rotation speed. 2) The feed liquid is injected into the feed port (2-1) of the high-speed rotating stator part (2) and enters the separation zone (3-1) along the entrances of multiple external spiral flow channels; 3) In the separation zone (3-1), the feed liquid has two flow modes: tangential flow and radial flow. In the tangential flow, most of the feed liquid flows along the outer spiral flow channel. During the tangential flow, the suspended or sol particles in the feed liquid slowly settle to the inclined surface of the outer spiral flow channel, and the particles slide outward along the outer spiral flow channel. In the radial flow, a small part of the feed liquid quickly passes through the slit between the top plate (3-6) and the inclined surface of the outer spiral flow channel, and at the same time, the particles sliding there are sheared and mixed into a high-concentration feed liquid. The high-concentration feed liquid continues to settle along the top plate (3-6) to the next level of slits, and then outwards, until it settles to the outermost collection tank (3-3); 4) When the tangential flow reaches the outermost layer of the outer spiral flow channel, the liquid continues to flow downward along the tangential direction into the reflux zone (3-2), which contains a plurality of inner spiral flow channels. The liquid rotates along the inner spiral flow channels and refluxes to the rotor part discharge port (3-5), is ejected from the rotor part discharge port (3-5) into the stator inner cavity of the ultra-gravity separator (4), and then flows out from the first discharge port (2-2) of the stator inner cavity; 5) After the radial flow enters the collecting tank (3-3), the high-concentration suspension is quickly deposited on the outermost side of the collecting tank (3-3), and the clear liquid enters the reflux zone (3-2) along the reflux channel (3-4). When the volume of the solid phase particles collected in the collecting tank (3-3) reaches a certain value, the feeding is stopped and the machine is shut down. After the ultra-gravity separator (4) is completely stopped and the feed liquid in the ultra-gravity separator (4) has all flowed out, the cover plate of the stator part (2) and the top plate (3-6) of the rotor part (3) are opened, the collecting tank (3-3) is taken out, and the wet filter cake is completely scraped off with a scraper. The collecting tank (3-3) is put back into the rotor part (3), and the top plate (3-6) of the rotor part (3) and the cover plate of the stator part (2) are buckled to prepare for the next round of centrifugal separation operation.

2. The method for separating nanomaterials by ultra-gravity according to claim 1, characterized in that: In the step 1), the supergravity field generated by the supergravity separator (4) gradually increases from the center to the outermost side, and the maximum supergravity field strength in the supergravity separator (4) is controlled to be between 2000 and 4000 g.

3. The method for separating nanomaterials by ultra-gravity according to claim 1, characterized in that: In the step 3), the slip angle of the outer spiral flow channel is 40-55°, the sedimentation distance of suspended or sol particles in the outer spiral flow channel is 15-30 mm, the width of the inclined surface of the outer spiral flow channel is not less than 60 mm, and the width of the slit between the inclined surface of the outer spiral flow channel and the top plate is 0.5-1.5 mm.

4. The method for separating nanomaterials by ultra-gravity according to claim 1, characterized in that: In the step 4), the flow cross section of the inner spiral flow channel is a rectangular plane with a constant height and a continuously narrowing width. The number of the inner spiral flow channels and the number of the outer spiral flow channels are equal, and both are not less than 4.

5. The method for separating nanomaterials by ultra-gravity according to claim 1, characterized in that: In the step 5), the ratio of the downward flow cross section of the outermost tangential flow of the outer spiral flow channel to the flow cross section of the reflow channel is 10-20.

6. The method for separating nanomaterials by ultra-gravity according to claim 1, characterized in that: The maximum sedimentation volume of the collecting tank (3-3) in step 5) is 60% of the volume of the collecting tank (3-3). When this volume is reached, the separation process should be stopped and the material should be discharged.

7. A super gravity separator, characterized in that: The invention comprises a motor (1), a stator part (2) and a rotor part (3), wherein the motor (1) is arranged at the bottom of an ultra-gravity separator (4), the stator part (2) is arranged at the top of the motor (1), and the rotor part (3) is arranged inside the stator part (2); The rotor part (3) comprises a collecting trough (3-3), a reflux channel (3-4), a rotor part discharge port (3-5), a top plate (3-6) and a turntable base (3-7); the top plate (3-6) and the turntable base (3-7) are tightly coupled together to form a rotor inner cavity and a rotor outer cavity; the rotor inner cavity is divided into a separation area (3-1) and a reflux area (3-2) by a fixed disc; the front side of the disc is engraved with an outer spiral flow channel; the back side of the disc is engraved with an inner spiral flow channel; a collecting trough (3-3) is fixedly arranged inside the rotor outer cavity; the collecting trough (3-3) is provided with a handle; the collecting trough (3-3) and the rotor inner cavity form a liquid circuit through the reflux channel (3-4); the rotor part discharge port (3-5) is arranged at the inner edge of the spiral flow channel in the inner cavity; The stator part (2) is a closed cylinder, and comprises a feed port (2-1), a first discharge port (2-2) and a second discharge port (2-3). The stator part (2) is divided into a stator inner cavity and a stator outer cavity by a circular baffle. The feed port (2-1) is arranged at the center of the stator cover plate, the first discharge port (2-2) is arranged at the bottom of the stator inner cavity, and the second discharge port (2-3) is arranged at the bottom of the stator outer cavity.

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