Method for supergravity separation of nanomaterials and supergravity separator

Abstract

The application provides a method and a high gravity separation nanomaterial machine, and belongs to the technical field of nanomaterial preparation, and comprises the following steps: 1) starting the high gravity separation machine to reach a set rotating speed; 2) feeding liquid into the feeding port of the machine, and entering the separation zone from the outer spiral flow channel entrance; 3) most of the feeding liquid flows along the outer spiral flow channel in a tangential direction, the particles in the feeding liquid are deposited on the inclined surface of the flow channel and slide outward, a small part of the feeding liquid gradually passes through the slits between the outer spiral flow channel and the top plate to produce shearing mixing effect on the sliding particles, and high-concentration suspension is formed and enters the collecting tank; 4) the feeding liquid leaves the separation zone, enters the backflow zone along the inner spiral flow channel entrance, and is sprayed out from the discharging port; and 5) the high-concentration suspension is rapidly deposited in the collecting tank, and the clear liquid enters the backflow zone from the backflow channel. The application significantly improves the separation efficiency, and can simply, rapidly, efficiently, at low cost and with high quality separate various nanomaterials.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nanomaterial preparation, and particularly relates to a method for separating nanomaterials by supergravity and a supergravity separator. BACKGROUND

[0002] Graphene preparation methods are divided into exfoliation method (top-down) and chemical vapor deposition method (bottom-up). The method of physical exfoliation can generally obtain a graphene product with few defects. Due to the limitation of each exfoliation method, 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 form of graphene in gas or liquid phase, which belongs to a mixing process. The use of different settling rates between slurry, suspension and sol to separate them step by step belongs to a separation process. Mixing is a combination of two, separation is a division of two, although the two processes are contrary, but they complement each other, and can be perfectly coupled together to form a process cycle. The cycle can significantly improve the yield of graphene.

[0003] The supergravity technology is a new technology for strengthening multiphase flow transmission and reaction process. Due to its wide applicability and advantages such as small size, light weight, low energy consumption, easy operation, easy maintenance, safety, reliability, flexibility and better environmental adaptability which are not possessed by traditional equipment, the supergravity technology has broad commercial application prospects in the fields of environmental protection, materials, biology, chemical industry and the like. The basic principle of supergravity engineering technology is to utilize the unique flow behavior of multiphase flow system under supergravity field conditions to strengthen the relative velocity and mutual contact between phases, so as to realize high-efficiency momentum, mass and heat transfer processes. The way to form the supergravity field is to form a centrifugal force field by rotating the whole or part of the equipment by a motor.

[0004] A method and device for continuously separating two-dimensional nanomaterials by supergravity disclosed in Chinese patent "A method and device for continuously separating two-dimensional nanomaterials by supergravity" (publication number: CN108993784B) discloses a method for purifying graphene. According to the U-shaped tube principle, the method and device for continuously separating two-dimensional nanomaterials by supergravity are designed. The graphite slurry containing graphene is continuously injected into the center feed port of the supergravity separator. The liquid is thrown out along the U-shaped tube channel. The high-concentration graphite slurry is thrown to the bottom of the U-shaped tube and sprayed out from the outermost upper spray port. The low-concentration graphene solution flows against the supergravity field in the U-shaped tube and is sprayed out from the inner lower spray port. A large number of experimental results show that due to the long settling distance, small settling area and large settling resistance of the method, the separation of graphene is slow, the efficiency is low, and the separation is not complete. The most fundamental reason is that the process is a pure separation process without the assistance of the mixing process, so the efficiency is low. SUMMARY

[0005] The application aims to provide a method and a high gravity separation nanometer material separator, which greatly improve separation efficiency with the aid of mixing process, and can realize simple, fast, efficient, energy-saving, low-cost, large-batch and high-quality separation of various nanometer materials.

[0006] To achieve the above object, the application provides the following technical scheme.

[0007] In a first aspect, a method for high gravity separation of nanometer material is provided, which comprises the following steps.

[0008] 1) The rotation speed of the high gravity separator is controlled by a frequency modulator, the frequency of the frequency modulator is set, the high gravity separator is started, the high gravity separator is accelerated to reach the set rotation speed, and the high gravity field strength is proportional to the square of the rotation speed.

[0009] 2) The liquid is injected into the feeding port of the stator part in high-speed rotation, and enters the separation zone along multiple outer spiral flow channels.

[0010] 3) In the separation zone, there are two flow modes of tangential flow and radial flow for the liquid, the tangential flow is that most of the liquid flows along the outer spiral flow channel, in the tangential flow process, the suspended or sol particles in the liquid slowly settle on the inclined surface of the outer spiral flow channel, and the particles slide outward along the outer spiral flow channel; the radial flow is that a small part of the liquid quickly passes through the gap between the top plate and the inclined surface of the outer spiral flow channel, and the particles that slide to the gap are sheared and mixed into high-concentration liquid, the high-concentration liquid continues to settle along the top plate to the next gap, and then outward, until it is collected in the outermost collection tank.

[0011] 4) When the tangential flow reaches the outermost layer of the outer spiral flow channel, the liquid continues to enter the reflux zone in a tangential direction, the reflux zone comprises multiple inner spiral flow channels, the liquid rotates back to the rotor part discharge port along the inner spiral flow channel, is sprayed into the stator inner cavity of the high gravity separator from the rotor part discharge port, and then flows out from the first discharge port of the stator inner cavity.

[0012] 5) When the radial flow enters the collection tank, the high-concentration suspension quickly deposits to the outermost side of the collection tank, the clear liquid enters the reflux zone along the reflux channel, when the volume of the solid-phase particles collected in the collection tank reaches a certain value, the feeding is stopped, the machine is turned off, after the high gravity separator is completely stopped and all the liquid in the high gravity separator is discharged, the cover plate of the stator part and the top plate of the rotor part are opened, the collection tank is taken out, the wet filter cake is scraped down with a scraper, the collection tank is put back into the rotor part, the top plate of the rotor part and the cover plate of the stator part are buckled, and the next centrifugal separation operation process is prepared.

[0013] Further, the super gravity field generated by the super gravity separator in step 1) gradually increases from the center to the outermost side, and the maximum super gravity field strength is controlled in the range of 2000-4000g.

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

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

[0016] Further, the ratio of the tangential flow direction of the outermost side of the outer spiral flow channel to the downflow cross section to the flow cross section of the backflow hole in step 5) is 10-20.

[0017] Further, the maximum precipitation volume of the collection tank in step 5) is 60% of the volume of the collection tank, and after reaching this volume, the separation process should be stopped and the material should be unloaded.

[0018] The second aspect is a super gravity separator, characterized in that:

[0019] The motor, the stator part and the rotor part are arranged in the bottom of the super gravity separator, the top of the motor, and the inside of the stator part.

[0020] The rotor part includes a collection tank, a backflow hole, a rotor part discharge port, a top plate and a rotating disc base, the top plate and the rotating disc base are tightly coupled together to form a rotor inner cavity and a rotor outer cavity, the rotor inner cavity is divided into a separation zone and a backflow zone by a fixed disc, the front surface of the disc is engraved with an outer spiral flow channel, the back surface of the disc is engraved with an inner spiral flow channel, the collection tank is fixedly arranged in the rotor outer cavity, the collection tank is provided with a handle, the collection tank and the rotor inner cavity form a material liquid circuit through the backflow hole, and the rotor part discharge port is arranged at the inner edge of the inner spiral flow channel in the inner cavity.

[0021] The stator part is a closed cylinder, the stator part includes a feeding 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 feeding 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] The advantages of the present application are:

[0023] 1. The method for separating nano-particles by high gravity has the advantages of high gravity field strength, 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 the process of separating various nano-materials simply, quickly, efficiently, energy-savingly, low-costly, in large batches and with high quality is realized.

[0024] 2. The high gravity separator has the advantages of simple structure, easy processing, easy control, easy cleaning, easy scale-up, easy automation and continuous production, etc.

[0025] 3. In actual application, the method and device can be used for separating various nano-particles from a suspended state to a sol state by adjusting the rotating speed, the flow of the liquid, or replacing the disc size, and have the advantages of large operation flexibility and strong adjustability. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 Fig. 1 is a structural schematic diagram of the high gravity separator in the application;

[0027] Figure 2 Fig. 2 is a schematic diagram of the outer spiral line formed by the intersection of the outer spiral flow channel and the front surface of the disc in the application;

[0028] Figure 3 Fig. 3 is a schematic diagram of the inner spiral line formed by the intersection of the inner spiral flow channel and the back surface of the disc in the application;

[0029] Figure 4 Fig. 4 is a process flow diagram of coupling the high gravity separator and the high gravity stripping machine to prepare the intermediate suspension in the application;

[0030] Fig. 1: 1, motor,

[0031] 2, stator part, 2-1, feed inlet, 2-2, first discharge port, 2-3, second discharge port,

[0032] 3, rotor part, 3-1, separation zone, 3-2, backflow zone, 3-3, collection tank, 3-4, backflow channel, 3-5, rotor part discharge port, 3-6, top plate, 3-7, rotating disc base,

[0033] 4, high gravity separator,

[0034] 5, high gravity stripping machine,

[0035] 6, graphite slurry,

[0036] 7, intermediate suspension,

[0037] 8, colorless clear liquid. DETAILED DESCRIPTION

[0038] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application.

[0039] As shown in Figures 1-4 A method for supergravity separation of nanomaterials, the method comprising the following steps:

[0040] 1) The rotation speed of the supergravity separator 4 is controlled by a frequency modulator, the frequency of the frequency modulator is set, the supergravity separator 4 is started, the supergravity separator 4 is intermittent, the supergravity separator 4 is accelerated to reach the set rotation speed, and the supergravity field strength is proportional to the square of the rotation speed.

[0041] 2) The feed liquid is injected into the feed inlet 2-1 of the high-speed rotating stator part 2, and enters the separation zone 3-1 along a plurality of outer spiral flow channel entrances.

[0042] 3) In the separation zone 3-1, there are two flow modes of tangential flow and radial flow of the feed liquid, the tangential flow flows along the direction of the outer spiral flow channel. The outer spiral flow channel has the characteristics of large settling area, short settling distance, and the flow direction of the feed liquid is nearly vertical to the settling direction of the material, and the settling process is basically not affected by the flow of the feed liquid, so that the rapid settling process of the particles can be realized. In the tangential flow process, the suspended or sol particles in the feed liquid slowly settle to the inclined outer spiral flow channel surface under the action of the supergravity field, the angle between the outer spiral flow channel and the rotating shaft of the separator is called the sliding angle, and the particles slide outward along the outer spiral flow channel. Since the concentration of the settling particles in the tangential flow is gradually reduced, the tangential flow belongs to the separation process. In the radial flow process, there is a very narrow gap 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 gap, the flow rate of the feed liquid in the gap is very fast, which can mix the particles sliding to the gap into high-concentration feed liquid through shearing action, and then the feed liquid flows along the top plate to the next level gap, and then outward, until it is collected in the outermost collection groove 3-3. In the tangential flow process, the concentration of the settling particles gradually decreases, which belongs to the separation process. In the radial flow process, the concentration of the settling particles gradually increases, which belongs to the mixing process. The higher the concentration of the settling particles, the faster the settling rate.

[0043] 4) When the tangential flow reaches the outermost layer of the outer spiral flow channel, the concentration of the particles in the feed liquid is reduced to the minimum, and the feed liquid continues to enter the reflux area 3-2 in the tangential direction. The reflux area 3-2 comprises a plurality of inner spiral flow channels, and has the characteristics of short reflux distance, large flow cross section, and small reflux resistance. From the overhead perspective, the directions of the outer spiral flow and the inner spiral flow are consistent, and are opposite to the rotation direction of the supergravity separator 4. This not only increases the driving force of the feed liquid flowing outward, but also reduces the resistance of the feed liquid reflux. The feed liquid rotates and refluxes along the inner spiral flow channel to the rotor part discharge port 3-5, is injected into the inner cavity of the stator of the supergravity separator 4 from the rotor part discharge port 3-5, and then flows out from the first discharge port 2-2 of the inner cavity of the stator.

[0044] 5) When the radial flow enters the collection tank 3-3, the high-concentration suspension is quickly deposited to the outermost side of the collection tank 3-3, and the clear liquid enters the reflux area 3-2 along the reflux hole 3-4. The flow ratio between the tangential flow of the outermost side of the outer spiral flow channel and the radial flow is determined by the flow cross section of the reflux hole. When the volume of the collected solid particles in the collection tank 3-3 reaches a certain value, the feeding is stopped, the machine is shut down, and after the supergravity separator 4 is completely stopped and all the feed liquid in the supergravity separator 4 flows out, the cover plate of the stator part 2 and the top plate 3-6 of the rotor part 3 are opened, the collection tank 3-3 is lifted out, the wet filter cake is scraped down with a scraper, the collection 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, so as to prepare for the next centrifugal separation operation process.

[0045] The supergravity separation method provided by the present application is only suitable for separating suspended or sol particles, and is not suitable for separating pure solid particles.

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

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

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

[0049] As a preferred embodiment of the present application, the ratio of the downflow cross section of the outermost tangential flow channel in step 5) to the cross section of the backflow channel is 10-20.

[0050] As a preferred embodiment of the present application, the maximum sedimentation volume of the collection tank 3-3 in step 5) is 60% of the volume of the collection tank 3-3, and the separation process should be stopped and the material unloaded after reaching this volume.

[0051] The high gravity separation method of the present application can achieve perfect coupling between high-efficiency separation and high-efficiency mixing, with separation as the main function and mixing as the auxiliary function, and the separation efficiency is much higher than that of traditional nanometer particle separation methods.

[0052] Based on the above-mentioned method for separating nanometer materials by high gravity, the present application further provides a high gravity separator 4, which comprises a motor 1, a stator part 2 and a rotor part 3, wherein the motor 1 is arranged at the bottom of the high 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 comprises a collection tank 3-3, a backflow channel 3-4, a rotor part discharge port 3-5, a top plate 3-6 and a rotating disc base 3-7, the top plate 3-6 and the rotating disc 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 zone 3-1 and a backflow zone 3-2 by a fixed disc, the front surface of the disc is engraved with an outer spiral flow channel, the back surface of the disc is engraved with an inner spiral flow channel, the collection tank 3-3 is fixedly arranged inside the rotor outer cavity, the collection tank 3-3 is provided with a handle, and the collection tank 3-3 can be taken out from the outer cavity, the collection tank 3-3 and the rotor inner cavity constitute a material liquid loop through the backflow channel 3-4, the rotor part discharge port 3-5 is arranged at the inner edge of the inner 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, the stator part 2 comprises a feeding 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 feeding 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 material liquid thrown out from the rotor part discharge port 3-5 is blocked in the stator inner cavity by the circular baffle, and only a small amount of mist droplets can be thrown into the stator outer cavity. If the high gravity separator 4 leaks, the material liquid flowing out of the stator outer cavity will significantly increase. This efficient intermittent high gravity separator has the advantages of easy automatic operation control, easy scale-up, easy industrialization application and the like.

[0056] Example 1:

[0057] An intermediate precipitate was prepared using isopropanol aqueous solution as the exfoliating solvent and graphite as the raw material via a supergravity coupling technique.

[0058] The supergravity peeling machine 5 is characterized by peeling as the primary function and separation as a secondary function, and it can operate continuously in a cycle. For example... Figures 1-4 As shown, in this embodiment, a small-scale gravity stripper 5 and two identical small-scale gravity separators 4 constitute a pilot-scale circulation system. The two gravity separators 4 are operated alternately. The circulation flow rate of this system is 24 L / min, the total volume of the gravity separators 4 is 8 L, and the average residence time of the liquid in the gravity separators 4 is 20 s. There are 8 inner and 8 outer spiral channels. The slip angle of the outer spiral channel is 40 degrees, the settling distance of the intermediate suspension 7 in the outer spiral channel is 30 mm, the length of the inclined surface of the outer spiral channel is 60 mm, the width of the slit between the inclined surface of the outer spiral channel and the top plate 3-6 is 1.5 mm, and the ratio of the tangential flow section of the outermost tangential flow of the outer spiral channel to the flow section of the return channel 3-4 is 20. The volume of the collection tank 3-3 is 3 L. When the volume of the intermediate sediment in the collection tank 3-3 reaches 60%, it is 1.8 L, and approximately 540 g of intermediate sediment can be obtained. Throughout the entire operating cycle, the concentration of the intermediate suspension 7 entering the centrifugal separator 4 is approximately 150 mg / L. The colorless clear liquid 8 flows out of the centrifugal separator 4 and then returns to the centrifugal stripper 5 via pipeline. The liquid circulates in an "∞" shape between the centrifugal stripper 5 and the centrifugal separator 4. The circulating liquid undergoes three different stages: graphite slurry 6 → intermediate suspension 7 → colorless clear liquid 8, while maintaining a constant flow rate throughout this process. After 150 minutes, the volume of intermediate sediment in collection tank 3-3 reaches 60%, at which point the two centrifugal separators 4 are rotated. After the centrifugal separator 4 has completely stopped rotating and all the liquid material in the centrifugal separator 4 has flowed out, open the cover plate of the stator section 2 and the top plate 3-6 of the rotor section 3, lift out the collection tank 3-3, scrape off all the wet filter cake of the intermediate sediment with a scraper, and then put the collection tank 3-3 back into the centrifugal separator 4, close the top plate 3-6 of the rotor section 3 and the cover plate of the stator section 2, and wait for the next rotation operation.

[0059] The motor 1 rotation speed of the super gravity separator 4 is controlled by a frequency converter, the frequency converter is connected with a 380V AC power supply, the frequency converter is set to 65Hz, and a maximum super gravity field strength corresponding to the frequency converter is 2000g. Before the two super gravity separators 4 start to rotate alternately, the frequency converter is started, the super gravity separator 4 starts to idle and gradually reaches the set 65Hz frequency, and the frequency converter displays the current flow at this time. After the current is stable, the rotation is started. After the material liquid with a flow of 24L / min enters the idling super gravity separator 4, the load of the super gravity separator 4 rapidly increases, and the current also rapidly increases. When the material liquid stably flows out of the super gravity separator 4, the current also tends to be stable. The flow of the material liquid entering the super gravity separator 4 has an upper limit of operation. If the flow exceeds the upper limit of operation, the super gravity separator 4 will vibrate violently, resulting in unstable operation, and even a serious accident may be caused. Therefore, the flow of the circulating material liquid needs to be monitored in real time, so that the flow fluctuation range is obviously lower than the upper limit of operation.

[0060] The scraped intermediate product precipitation wet cake is mixed with the stripping solvent again, and is dispersed into a uniformly distributed suspension in a crusher, and the concentration is about 600mg / L. A new stripping method is used to strip the intermediate product suspension 7, and the stripping method is not within the scope of the present application. The intermediate product suspension needs to be separated once for each stripping. The separation operation is divided into two steps: in the first step, the intermediate product suspension 7 is separated from the graphene sol in the form of a precipitate (Example 2); and in the second step, the graphene sol is separated from the colorless clear liquid 8 in the form of a precipitate (Example 3).

[0061] Example 2

[0062] In this embodiment, two small-scale high gravity separators 4 are used to achieve the separation of the intermediate suspension 7 from the graphene sol. The two high gravity separators 4 used in this embodiment are basically the same as those used in embodiment 1, with the following differences: first, the width of the gap 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 cross-sectional area of the tangential flow channel at the outermost side of the outer spiral flow channel to the cross-sectional area of the backflow channel 3-4 is 15. The feed flow rate is controlled at 12 L / min, and the average residence time of the feed in the high gravity separator 4 is 40 s. The frequency of the frequency modulator for controlling the rotation speed of the motor 1 is set at 80 Hz, corresponding to a maximum high gravity field strength of 3000 g. When the volume of the intermediate deposited in the collection tank 3-3 reaches 1.8 L, about 450 g of the intermediate can be obtained. The concentration of the intermediate suspension 7 entering the high gravity separator 4 remains essentially unchanged, and after about 60 min, the volume of the deposit in the collection tank 3-3 reaches 1.8 L, and the two high gravity separators 4 are switched. The wet cake of the intermediate in the collection tank 3-3 is scraped off with a spatula, mixed with the stripping solvent again, dispersed in a breaker to form a suspension with a concentration of about 600 mg / L, and then subjected to stripping operation again. The feed liquid sprayed from the rotor part discharge port 3-5 is a light black graphene sol with a concentration of about 40 mg / L.

[0063] Example 3

[0064] In this embodiment, two small-scale high gravity separators 4 are used to achieve the separation of the intermediate suspension 7 from the graphene sol. The two high gravity separators 4 used in this embodiment are basically the same as those used in embodiment 1, with the following differences: first, the width of the gap 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 cross-sectional area of the tangential flow channel at the outermost side of the outer spiral flow channel to the cross-sectional area of the backflow channel 3-4 is 15. The feed flow rate is controlled at 12 L / min, and the average residence time of the feed in the high gravity separator 4 is 40 s. The frequency of the frequency modulator for controlling the rotation speed of the motor 1 is set at 80 Hz, corresponding to a maximum high gravity field strength of 3000 g. When the volume of the intermediate deposited in the collection tank 3-3 reaches 1.8 L, about 450 g of the intermediate can be obtained. The concentration of the intermediate suspension 7 entering the high gravity separator 4 remains essentially unchanged, and after about 60 min, the volume of the deposit in the collection tank 3-3 reaches 1.8 L, and the two high gravity separators 4 are switched. The wet cake of the intermediate in the collection tank 3-3 is scraped off with a spatula, mixed with the stripping solvent again, dispersed in a breaker to form a suspension with a concentration of about 600 mg / L, and then subjected to stripping operation again. The feed liquid sprayed from the rotor part discharge port 3-5 is a light black graphene sol with a concentration of about 40 mg / L.

[0065] The above merely describes the preferred embodiments of the present application and is not intended to limit the present application. Those skilled in the art can still adjust the technical solutions described in the foregoing embodiments or make equivalent replacement for some technical features. Therefore, the present application also intends to include these modifications and variations within the scope of the present application claims and equivalent technologies.

Claims

1. A method for separating nanomaterials under supergravity, characterized in that: The method includes the following steps: 1) The rotation speed of the supergravity separator (4) is controlled by the frequency modulator. After setting the frequency of the frequency modulator, start the supergravity separator (4). The supergravity separator (4) accelerates to the set rotation speed. The supergravity field strength is proportional to the square of the rotation speed. 2) The liquid feed is injected into the feed inlet (2-1) of the high-speed rotating stator section (2) and enters the separation zone (3-1) along multiple external spiral flow channels; 3) In the separation zone (3-1), the liquid has two flow modes: tangential flow and radial flow. In tangential flow, most of the liquid flows along the outer spiral channel. During the tangential flow, the suspended or colloidal particles in the liquid slowly settle to the inclined surface of the outer spiral channel and slide outward along the outer spiral channel. In radial flow, a small portion of the liquid passes quickly through the slit between the top plate (3-6) and the inclined surface of the outer spiral channel. At the same time, the particles that slide there are sheared and mixed into a high-concentration liquid. The high-concentration liquid continues to settle along the top plate (3-6) to the next level slit, and so on outward until it settles into the outermost collection tank (3-3). 4) When the tangential flow reaches the outermost layer of the outer spiral channel, the liquid continues to flow downward in the tangential direction into the reflux zone (3-2). The reflux zone (3-2) contains multiple inner spiral channels. The liquid rotates and flows back along the inner spiral channels to the rotor section outlet (3-5). It is then sprayed from the rotor section outlet (3-5) into the stator cavity of the supergravity separator (4) and flows out from the first outlet (2-2) of the stator cavity. 5) When the radial flow enters the collection tank (3-3), the high-concentration suspension quickly settles to the outermost side of the collection tank (3-3), and the clear liquid enters the reflux zone (3-2) along the reflux channel (3-4). When the volume of solid particles collected in the collection tank (3-3) reaches a certain value, the feeding is stopped and the machine is turned off. After the centrifugal separator (4) has completely stopped and all the liquid in the centrifugal separator (4) has flowed out, the cover plate of the stator part (2) and the top plate (3-6) of the rotor part (3) are opened, the collection tank (3-3) is lifted out, the wet filter cake is scraped off with a scraper, the collection tank (3-3) is put back into the rotor part (3), the top plate (3-6) of the rotor part (3) and the cover plate of the stator part (2) are closed, and the next round of centrifugal separation operation is prepared.

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

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

4. The method for separating nanomaterials under supergravity according to claim 1, characterized in that: In step 4), the flow cross section of the inner spiral channel is a rectangular plane with a constant height and a continuously narrowing width. The number of inner spiral channels and outer spiral channels is equal, and there are no fewer than 4 channels.

5. The method for separating nanomaterials under supergravity according to claim 1, characterized in that: In step 5), the ratio of the tangential flow section of the outermost outermost spiral channel to the flow section of the return channel is between 10 and 20.

6. The method for separating nanomaterials under supergravity according to claim 1, characterized in that: In step 5), the maximum sedimentation volume of the collection tank (3-3) is 60% of the volume of the collection tank (3-3). Once this volume is reached, the separation process should be stopped and the material unloaded.

7. A centrifugal separator, characterized in that: It includes a motor (1), a stator section (2) and a rotor section (3). The motor (1) is located at the bottom of the supergravity separator (4), the stator section (2) is located at the top of the motor (1), and the rotor section (3) is located inside the stator section (2). The rotor part (3) includes a collection tank (3-3), a reflux channel (3-4), a rotor part outlet (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 fastened together to form the rotor inner cavity and the rotor outer cavity. The rotor inner cavity is divided into a separation zone (3-1) and a reflux zone (3-2) by a fixed disc. The front of the disc is engraved with an outer spiral flow channel, and the back of the disc is engraved with an inner spiral flow channel. The collection tank (3-3) is fixedly installed inside the rotor outer cavity. The collection tank (3-3) is equipped with a handle. The collection tank (3-3) and the rotor inner cavity form a liquid circuit through the reflux channel (3-4). The rotor part outlet (3-5) is located on the inner edge of the spiral flow channel inside the inner cavity. The stator section (2) is a closed cylinder. The stator section (2) includes a feed inlet (2-1), a first discharge outlet (2-2), and a second discharge outlet (2-3). The stator section (2) is divided into an inner stator cavity and an outer stator cavity by a circular baffle. The feed inlet (2-1) is located at the center of the stator cover plate. The first discharge outlet (2-2) is located at the bottom of the inner stator cavity. The second discharge outlet (2-3) is located at the bottom of the outer stator cavity.

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