CN109437170B - Equipment and method for preparing graphene and graphene prepared by equipment and method - Google Patents

Abstract

The invention is suitable for the technical field of graphene, and comprises a first air inlet unit, wherein the first air inlet unit is connected with a first airflow accelerator, the first airflow accelerator is connected with a first airflow mill, the first airflow mill is also respectively connected with a first feeding machine, a first milling bin and a first classifier, the first classifier is connected with a graphene nanosheet collecting bin, the graphene nanosheet collecting bin is connected with a transition bin through a conveyor, the transition bin is connected with a high-pressure respirator through a second feeding machine, and the high-pressure respirator is also connected with a second air inlet unit, a transition collector, a second airflow accelerator and an exhaust device; the production process of the invention has two production processes, wherein the first production line is used for producing graphite into graphene nanosheets, the second production line is used for processing the graphene nanosheets into single-layer, few-layer and multi-layer graphene, the two production lines complement each other, the adaptability of the raw material graphite is strong, various types of graphite can be selected, and the production cost is reduced.

Description

Equipment and method for preparing graphene and graphene prepared by equipment and method

Technical Field

The invention relates to the technical field of graphene, in particular to equipment and a method for preparing graphene and the prepared graphene.

Background

Graphene is a two-dimensional honeycomb structure formed by arranging planar single-layer carbon atoms, and is an ultrathin material with the thickness of only one carbon atom. Graphene is naturally present in nature, and it is difficult to exfoliate a single-layer structure. The graphene is graphite laminated one on top of another, with a layer spacing of 0.335 nm, and graphite having a thickness of 1mm contains approximately 300 million layers of graphene. The graphene has abundant physical characteristics, and the specific surface area reaches 2600m 2/g; the mechanical property is excellent, the breaking strength can reach 42N/m, the tensile strength and the elastic modulus are respectively 130GPa and 1.0TPa, and the elastic extension can reach 20%; the heat conductivity is good, and the heat conductivity is as high as 5300W/(m.K) at room temperature; the transparency is high, and the light absorption rate is only 2.3%. Meanwhile, the graphene also has excellent electrochemical performance, and the electron mobility of the graphene exceeds 15000cm2/(V & s) at normal temperature and is higher than that of a carbon nano tube. The excellent optical, electrical, mechanical and thermal properties of graphene promote researchers to carry out intensive research on the graphene, and as the preparation method of the graphene is continuously developed, the graphene is certainly and widely applied to various fields in the near future.

Currently, the preparation methods of graphene mainly include a chemical reduction graphene oxide method, a chemical vapor deposition method, a crystal epitaxial growth method, a mechanical exfoliation method, and the like. The chemical reduction graphene oxide method is an important method for realizing the most possible industrial preparation of graphene, wherein the chemical reduction graphene oxide method is to fully strip graphite oxide in water and then carry out chemical reduction or thermal reduction on the graphite oxide to obtain graphene. However, the electron conjugated structure of the graphene sheet layer is destroyed through a strong oxidation-reduction process, and the physicochemical properties of the graphene sheet layer are reduced. And in the oxidation process of the graphite, high-temperature treatment is required, or toxic chemical substances such as hydrazine hydrate, sodium borohydride and the like are used, so that the energy consumption is high, the efficiency is low, the cost is high, and the environment is polluted.

The patent application No. CN201610255327.2 discloses a method for rapidly preparing high-quality graphene, graphite powder and a solid intercalation agent which can be completely decomposed into gas after being heated are mixed, ball-milled and properly heated to realize intercalation, then microwave radiation treatment of 100-1200W is carried out for 0.05-10 min, the intercalation agent is completely decomposed into gas at high temperature, gas molecules permeate into a graphite sheet layer and overcome van der Waals force among the graphite sheet layers, and graphite is effectively stripped. The invention has the advantages of relatively simple preparation process, relatively low manufacturing cost, easy large-scale use and the like. However, due to intercalation high-temperature stripping, graphene cannot be completely stripped, only multilayer graphene or graphene nanosheets can be produced, and single-layer or few-layer graphene is difficult to produce in large batch.

Patent application No. CN201610057892.8 discloses "impact flow 3 mach graphite alkene production line", it includes feed mechanism, accelerating mechanism, impact mechanism and injection mechanism, feed mechanism is for carrying the graphite powder to accelerating mechanism's device, accelerating mechanism is for accelerating the graphite powder to the device more than 1.2 mach, accelerating mechanism is connected with impact mechanism, be provided with the base plate at injection mechanism's exit end, injection mechanism is for spouting out and striking the device on the base plate with the graphite powder after the striking. The equipment has simple structure, convenient production process, environmental protection and no pollution. But the graphene directly impacts on the substrate, so that the substrate is easy to wear, and qualified graphene cannot be produced due to one-time impact, and the practical use value is not high.

Patent application No. CN201310757079.8 discloses a method for preparing graphene nano sheets, a graphene nano sheet, graphene nano sheet slurry and a conductive layer comprising the graphene nano sheet, which adopts intercalation, microwave or heat treatment technology to prepare expanded graphite, and then generates nano sheets by gas phase high-speed collision. In the intercalation process, chemical raw materials are used, which not only pollutes graphite, but also discharges industrial sewage and is not environment-friendly. The finished product is graphene nano sheet slurry which comprises a conductive coating and is a wet material. The thickness of the graphene nanosheet is 5 nm-100 nm, the graphene nanosheet is not graphene in a real sense, and the graphene nanosheet only belongs to the graphene nanosheet.

The patent application number CN201711038875.0 discloses a physical stripping production method of graphene and the produced graphene, which comprises the steps of taking high-purity flaky graphite as a raw material for producing the graphene, taking steel balls and zinc-magnesium alloy powder as ball-milling stripping media, putting the flaky graphite and the ball-milling stripping media into a ball mill, carrying out ball-milling stripping under the protection of nitrogen, and separating graphene sheets stripped by the ball mill through air flow classification under the protection of inert gas after stripping is finished. Its disadvantages are that a ball mill is used, the rotation speed of the ball mill is 50-55 rpm, the linear speed is below 8 m/s, the stripping time is 200-300 h, the stripping efficiency is low, and the yield is low. Meanwhile, the thickness of the graphene is not controllable, and the product quality is low.

Patent application No. CN201610510419.0 discloses a method for preparing a graphene material by dry airflow stripping and a graphene material, wherein the graphene material is obtained by microscopic cutting, grinding and friction stripping of graphite under the action of graphite powder through composite inorganic powder with different shapes, different hardness or/and different particle sizes and shear force difference in high-speed airflow under the action of complete airflow. The energy is transferred by the aid of the composite inorganic powder in high-speed airflow, the defect that the ball milling is difficult to grind and thin is overcome, and the obtained graphene material is uniform in distribution, high in compactness and free of agglomeration and can be directly added and used in battery materials, rubber, plastics, coatings, lubricating oil and the like. Particularly, the composite inorganic powder is finally retained in the graphene material without being removed, and the number of graphene sheets is between 100 and 200. The biggest defect of the patent is that only graphene nanosheets can be produced, and meanwhile, the composite inorganic powder is finally retained in the graphene material, so that the graphene is low in quality.

Patent application No. CN201610936658.2 discloses a 'complete equipment for stripping graphene in dry conical grinding', and discloses complete equipment for stripping graphene in dry conical grinding, which comprises a shearing and dispersing function pre-reaction device, a conical grinding high-pressure resistant stripping device, an airflow classification system and a recovery system. Heating to 400-600 ℃ by a microwave preheating device, controlling the microwave preheating time within 10 s-50 min, so that the graphite raw material forms micro-expanded graphite, then transferring the micro-expanded graphite and the intercalation solution metered by a intercalation solution feed inlet to a stirring device together for pre-intercalation reaction to ensure that the graphite and the intercalation solution are fully mixed, improving the intercalation reaction efficiency, and finally transferring the obtained intermediate product to a conical grinding high-pressure resistant stripping device through a guide pipe after being separated by a centrifugal separation device and treated by a drying device. This patent has used the intercalation liquid, need to adorn and drying device with microwave preheating, and the production process has sewage, and is not environmental protection, and the energy consumption is high simultaneously.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides equipment and a method for preparing graphene and the prepared graphene, and the technical scheme is as follows:

the utility model provides an equipment of preparation graphite alkene, includes first air intake unit, first air intake unit connects first air current accelerator, first air current accelerator is connected first jet mill, first jet mill still is connected with first feeding machine, first mill grain storehouse, first grader respectively, first grader is connected with graphite alkene nanometer piece collecting bin, graphite alkene nanometer piece collecting bin passes through the conveyer and connects transition bin, the transition bin passes through second feeding machine and connects high pressure respirator, high pressure respirator still is connected with second air intake unit, transition collector, second air current accelerator, exhaust apparatus, second air intake unit still connects the one end of second air current accelerator, the other end of second air current accelerator is connected the second jet mill, the second jet mill still is connected with second grader, second mill grain storehouse, the second grader still is connected with transition collector, transition collector, Storehouse is collected to graphite alkene.

Further, first feeding machine still is connected with former feed bin, first environment dust excluding hood is installed at former feed bin top, environment dust remover is connected to first environment dust excluding hood, environment dust remover still is connected with the second environment dust excluding hood.

Further, the graphene nanosheet collecting bin is also connected with one end of a first dust remover, and the other end of the first dust remover is connected with a first fan; the bin is collected to graphite alkene still is connected with packagine machine, packagine machine dust remover respectively, install the packagine machine dust excluding hood on the packagine machine, the packagine machine dust excluding hood still connects the one end of packagine machine dust remover, the second fan is connected to the other end of packagine machine dust remover.

Further, the first air inlet unit comprises a first air storage tank, a first dryer, a first air compressor and a first air source, one end of the first air storage tank is connected with the first airflow accelerator, the other end of the first air storage tank is connected with one end of the first dryer, the other end of the first dryer is connected with one end of the first air compressor, the other end of the first air compressor is connected with the first air source, and the first air source is any one of air, argon, nitrogen and carbon dioxide.

Further, the high-pressure respirator is respectively connected with a second air storage tank and the jet mill through air pipes; the trachea includes first trachea and second trachea, first tracheal one end is connected high pressure respirator, and the other end is connected second trachea middle part position, the tracheal left end of second is connected second air current accelerator, right-hand member are connected the second gas holder, the second pneumatic valve is installed in the tracheal middle part position left side of second, and first pneumatic valve is installed on middle part position right side.

Further, still include first butterfly valve, second butterfly valve, first butterfly valve one end is passed through the pipe connection high pressure respirator, the other end passes through the pipe connection the second feeding machine, second butterfly valve one end is passed through the pipe connection the second grader, the other end passes through the pipe connection the transition collecting bin.

Further, the second air inlet unit comprises a second air storage tank, a second dryer, a second air compressor and a second air source, one end of the second air storage tank is respectively connected with the high-pressure respirator and the airflow accelerator, the other end of the second air storage tank is connected with one end of the second dryer, the other end of the second dryer is connected with one end of the second air compressor, the other end of the second air compressor is connected with the second air source, and the second air source is any one of air, argon, nitrogen and carbon dioxide.

Based on the same conception, the invention also provides a method for preparing graphene, which adopts the graphene preparation equipment to prepare graphene and comprises the following steps:

and S1, mixing graphite with a first gas source and first abrasive particles in a first jet mill to form mixed gas flow, wherein the graphite is selected from one or more of crystalline flake graphite, expandable graphite, expanded graphite, oxidized graphite, modified graphite, intercalated graphite, graphite nanosheets, aphanitic graphite, dense crystalline graphite and artificial graphite.

S2: introducing the mixed gas flow in the S1 into a first classifier, wherein the rotating speed of the first classifier is 2000-10000 r/min, and separating graphite from first abrasive particles in the first classifier to obtain a graphene nanosheet, wherein the thickness of the graphene nanosheet is 200-500 nm;

s3, introducing the graphene nanosheets in the S2 into a high-pressure respirator, simultaneously accessing a second gas source into the high-pressure respirator, and mixing the graphene nanosheets and the second gas source in the high-pressure respirator to form a first mixed gas flow;

s4, enabling the first mixed gas to enter a second jet mill after being accelerated by a second jet accelerator, and enabling the first mixed gas to rub with second abrasive particles in the second jet mill to form a first graphene jet mixture;

s5: the first graphene airflow mixture body in the S4 is connected into a second classifier, the rotating speed of the second classifier is 1000-5000 r/min, abrasive particles and graphene are separated, and primary graphene is obtained;

s6, enabling the primarily-prepared graphene to enter a high-pressure respirator through a transition collector, mixing the primarily-prepared graphene with a second air source again to form a second mixed air flow, enabling the second mixed air flow to enter a second jet mill after the second mixed air flow is accelerated through a second air flow accelerator, enabling the second mixed air flow to rub with second abrasive particles in the second jet mill to form a second graphene air flow mixture, enabling the second graphene air flow mixture to be connected into a second classifier, enabling the rotation speed of the second classifier to be 1000-5000 r/min, and enabling the abrasive particles and the graphene to be separated to obtain secondary-prepared graphene;

s7: repeating the step S6 for N times to obtain a primary graphene finished product, wherein N is 1-200, and the single cycle working time is 1-30 min;

and S8, putting the finished graphene product into a graphene collecting bin, and packaging by a packaging machine to obtain the finished graphene product.

Based on the same conception, the invention also provides the graphene obtained by the equipment and the method, and the finished graphene product comprises single-layer graphene, few-layer graphene and multi-layer graphene, wherein the thickness of the single-layer graphene is less than 0.6nm, the thickness of the few-layer graphene is less than 5nm, and the thickness of the multi-layer graphene is less than 100 nm.

The invention has the following advantages:

1. the production process is dry by adopting a physical method, does not adopt liquids such as intercalation liquid, sulfuric acid and the like, does not discharge sewage, is provided with a plurality of dust removing devices, extracts dust under the negative pressure in a production workshop, reduces the dust discharge, and is green and environment-friendly;

2. the production process comprises two production processes, wherein the first production line is used for producing graphite into graphene nanosheets, the second production line is used for processing the graphene nanosheets into single-layer, few-layer and multi-layer graphene, the two production lines complement each other, the adaptability of the raw material graphite is strong, various types of graphite can be selected, and the production cost is reduced;

3. the production process is dry, no liquid material is added, no chemical reaction is caused, heating and drying are not required, and the production process is energy-saving;

4. the product production is fully mechanized, no chemical is added, no modification is carried out, the chemical characteristics are not changed, the graphene can keep a complete grid structure, and the product quality is high;

5. the shear resistance between the graphene layers is about 40KPa, the shear force selected by the first abrasive particles and the second abrasive particles is 400 KPa-1.0 TPa which is far higher than the shear resistance between the graphene layers by 40KPa, the loss of the abrasive particles can be reduced, the abrasive particles can be recycled, and the production cost is low;

6. the second jet mill, the second classifier, the third air valve, the transition collector, the second butterfly valve, the high-pressure respirator, the second air valve and the second jet accelerator form a closed loop cycle. Setting the circulation to be N times in the second process, wherein before the N times of circulation, the graphene enters the transition collector channel through the third air valve and continues to circulate; and when the number of times reaches N, the graphene enters the graphene collecting bin channel through the fourth air valve. Through controlling the cycle number N, the thickness of the graphene is controlled, the thickness of the graphene can be randomly selected between 0.3-30 nanometers, and high-quality graphene with uniform quality is produced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a schematic structural diagram of an apparatus for preparing graphene according to the present invention;

FIG. 2 is a schematic flow structure diagram of a production process for preparing graphene nanoplatelets according to the present invention;

FIG. 3 is a schematic flow structure diagram of the production process for preparing graphene finished products according to the present invention;

labeled as:

1. a first air inlet unit 101, a first air source 102, a first air compressor 103, a first dryer 104, a first air storage tank 2, a first airflow accelerator 3, a first airflow mill 4, a first milling grain bin 5, a first classifier 6, a first feeder 7, a raw material bin 8, an environmental dust collector 91, a second environmental dust hood 92, a first environmental dust hood 10, a graphene nano-sheet collecting bin 11, a first dust collector 12, a first fan 13, a transition bin 14, a second feeder 15, a transition collector 16, an exhaust device 17, a high-pressure respirator 18, a second airflow accelerator 19, a second airflow mill 20, a second classifier 21, a second milling grain bin 22, a packer 23, a packer dust hood 24, a graphene collecting bin 25, a packer dust collector 26, a second fan 27, a second air inlet unit, 271. a second air source 272, a second air compressor 273, a second dryer 274, a second air storage tank 28, a conveyor 29, a first butterfly valve 30, a first air valve 31, a second air valve 32, a third air valve 33, a fourth air valve 34 and a second butterfly valve.

Detailed Description

In order to make those skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Referring to fig. 1, an apparatus for preparing graphene includes a first air inlet unit 1, the first air inlet unit 1 is connected to a first airflow accelerator 2, the first airflow accelerator 2 is connected to a first airflow mill 3, the first airflow mill 3 is further connected to a first feeder 6, a first milling bin 4, and a first classifier 5, respectively, the rotation speed of the first classifier 5 is 2000-10000 r/min, the faster the rotation speed of the first classifier 5 is, the smaller the particle size of a graphene nanosheet is, the thinner the thickness of the nanosheet is, but a critical value of 10000r/min is also existed, and the grid structure of the nanosheet is destroyed when the critical value is exceeded, so that the quality of the produced nanosheet is poor, and the produced graphene nanosheet enters a graphene nanosheet collecting bin 10 through the first classifier 5 under the driving of negative pressure airflow. First abrasive particles are placed in the first abrasive particle bin 4, the particle size range of the first abrasive particles is 10 um-1 mm, 400 KPa-1.0 TPa is selected as shearing force, the material of the first abrasive particles can be one or more of graphite, diamond, metal particles, ceramic particles, alloy particles and nonmetal particles, meanwhile, the second abrasive particles can be recycled, in order to achieve better effect, the particle size of the first abrasive particles is preferably 20 um-100 um, and the shearing force of the abrasive particles is preferably 10 MPa-500 MPa. The first classifier 5 is connected with a graphene nanosheet collecting bin 10, the graphene nanosheet collecting bin 10 is connected with a transition bin 13 through a conveyor 28, the transition bin 13 is connected with a high-pressure respirator 17 through a second feeding machine 14, the high-pressure respirator 17 is further connected with a second air inlet unit 27, a transition collector 15, a second airflow accelerator 18 and an exhaust device 16, the second air inlet unit 27 is further connected with one end of the second airflow accelerator 18, the other end of the second airflow accelerator 18 is connected with a second airflow mill 19, the second airflow mill 19 is further connected with a second classifier 20 and a second grinding bin 21, the second classifier 20 is further connected with the transition collector 15 and a graphene collecting bin 24, and the graphene nanosheets in the airflow can be collected through one of a cyclone collector, a cloth bag or an electrostatic collector and then enter the graphene collecting bin 24.

The first feeder 6 can be one or more of a screw conveyor 28, a belt conveyor 28, a vibrating feeder, an impeller feeder and an airflow feeder, the first feeder 6 is also connected with a raw material bin 7, the top of the raw material bin 7 is provided with a first environmental dust hood 92, the first environmental dust hood 92 is connected with an environmental dust remover 8, and the environmental dust remover 8 is also connected with a second environmental dust hood 91; the graphene nanosheet collecting bin 10 is further connected with one end of a first dust remover 11, and the other end of the first dust remover 11 is connected with a first fan 12; the graphene collecting bin 24 is further respectively connected with a packaging machine 22 and a packaging machine dust remover 25, a packaging machine dust hood 23 is mounted on the packaging machine 22, the packaging machine dust hood 23 is further connected with one end of the packaging machine dust remover 25, and the other end of the dust remover is connected with a second fan 26. Collecting dust through a dust hood of the raw material bin 7 when graphite is put in, collecting dust through a dust hood 23 of a packaging machine when the graphite is packaged, wherein the packaging machine 22 can be an open type packaging machine 22 or a valve port type packaging machine 22; the workshop has 2 ~ 15 second environment dust excluding hood 91. The environmental dust remover 8 and the packaging machine dust remover 25 are used, and no dust is leaked in the production process. Particularly, the environmental dust collector 8 is used, negative pressure is generated in a production workshop, and all workshop leaked dust is collected by the environmental dust collector 8. Because no dust leaks out, the utilization rate of the raw materials is extremely high.

The first dust remover 11 can be any one of a bag-type dust remover, an electrostatic dust remover, an electric-bag combined type dust remover or a spray dust remover, removes dust from the tail gas of the graphene nanosheet collecting bin 10, meets the national environmental protection requirement, and the first fan 12 can provide negative pressure and air volume for the first classifier 5, the graphene nanosheet collecting bin 10 and the first dust remover 11; the environment dust collector 8 generates negative pressure to carry out environment dust collection on a workshop where the production line is located, and the production process is ensured to be free of dust.

First air inlet unit 1 includes first gas holder 104, first desiccator 103, first air compressor machine 102, first air supply 101, and first air flow accelerator 2 is connected to the one end of first gas holder 104, and the one end of first desiccator 103 is connected to the other end, and the one end of first air compressor machine 102 is connected to the other end of first desiccator 103, and first air supply 101 is connected to the other end of first air compressor machine 102, and first air supply 101 is one of air, argon gas, nitrogen gas, carbon dioxide. The air source pressure of the first air compressor 102 reaches 0.3-0.8 MPa, moisture in the air source is removed through the first dryer 103, the relative humidity is lower than 30%, and the first air storage tank 104 provides the air source with relatively stable pressure for the first accelerator.

Second abrasive particles are placed in the second abrasive particle bin 21, the particle size range of the second abrasive particles is 10-1 mm, 1.0 MPa-1.0 TPa is selected as shearing force, the material of the second abrasive particles is one or more of graphite, diamond, metal particles, ceramic particles, alloy particles and nonmetal particles, and the second abrasive particles are recycled in the second jet mill 19; in order to achieve better use effect, the grain diameter of the second abrasive grain is preferably 20-100 um, and the shearing force of the second abrasive grain is preferably 10-500 MPa; the rotating speed of the second classifier 20 is 1000-5000 r/min, and the second abrasive particles and the graphene nanosheets are separated through the machine. The rotation generates centrifugal force, the second abrasive particles are thick and large in centrifugal force, under the action of the centrifugal force of the second classifier 20 and the self gravity, the second abrasive particles are thrown to the four walls and settled, the second abrasive particles return to the second jet mill 19 to be continuously recycled, the graphene is separated from the second abrasive particles, and the graphene is driven by negative pressure airflow to pass through the second classifier 20 device and enter the next procedure.

The high-pressure respirator 17 is respectively connected with a second air storage tank 274 and an airflow mill through air pipes; the trachea includes first trachea and second trachea, and high pressure respirator 17 is connected to first tracheal one end, and the other end is connected at second trachea middle part position, and second air current accelerator 18 is connected to the tracheal left end of second, and second gas holder 274 is connected to the right-hand member, and second pneumatic valve 31 is installed in the tracheal middle part position left side of second, and first pneumatic valve 30 is installed on middle part position right side, and first pneumatic valve 30 is the air supply switch of high pressure respirator 17. When the high pressure ventilator 17 is to be fed or exhausted, it shuts off the gas supply; when the high pressure ventilator 17 is to discharge, it opens the air valve to allow high pressure air flow into the ventilator.

The high pressure ventilator 17 works intermittently and has both high pressure container and breathing functions. Before feeding, the internal pressure is exhausted through an exhaust device 16, and the graphene raw material enters. And during feeding, the first butterfly valve 29, the second butterfly valve 34 and the exhaust device 16 are closed, the first air valve 30 and the second air valve 31 are opened, and the graphene nanosheets are fed out under the pushing of a compressed air source. The graphene nanosheets and the airflow form a second mixed airflow in high-pressure respiration, when the high-pressure respirator 17 is used for feeding, the exhaust equipment needs to be opened, and when the high-pressure respirator is used for discharging, the exhaust equipment needs to be closed; the filter arranged on the exhaust device 16 also comprises a first butterfly valve 29 and a second butterfly valve 34, one end of the first butterfly valve 29 is connected with the high-pressure respirator 17 through a pipeline, the other end of the first butterfly valve is connected with the second feeding machine 14 through a pipeline, the second feeding machine 14 can select any one of a screw conveyor 28, a bucket conveyor 28, a pneumatic conveyor 28 and a blade feeder, one end of the second butterfly valve 34 is connected with the high-pressure respirator 17 through a pipeline, and the other end of the second butterfly valve is connected with the transition collection bin through a pipeline; the first butterfly valve 29 is a switch interface between the second feeding machine 14 and the high-pressure breathing machine 17, when the graphene nano sheets enter the high-pressure breathing machine 17, the first butterfly valve 29 is opened, and is closed at other times, and the second butterfly valve 34 is a discharge switch of the high-pressure breathing machine 17. The high-pressure breathing discharge is opened during discharging and closed at other times.

The second air inlet unit 27 comprises a second air storage tank 274, a second dryer 273, a second air compressor 272 and a second air source 271, one end of the second air storage tank 274 is connected with the high-pressure respirator 17, the other end of the second air storage tank 274 is connected with one end of the second dryer 273, the other end of the second dryer 273 is connected with one end of the second air compressor 272, the other end of the second air compressor 272 is connected with the second air source 271, and the second air source 271 is one of air, argon, nitrogen and carbon dioxide; the second air compressor 272 is pressurized by an air compressor or a Roots blower, so that the air source pressure reaches 10-900 KPa atmospheric pressure, and the air compressor is preferably selected and used, and the pressure is 0.3-0.8 MPa.

It should be noted that the first jet mill 3 and the second jet mill 19 have the following differences:

1. the gas flow is different, the first gas flow mill 3 uses a single gas flow, namely a first gas source 101, and the first gas source 101 is selected from any one of air, argon, nitrogen and carbon dioxide; the second jet mill 19 is a mixed gas flow of the second gas source 271 and the first mixed gas flow, the graphene nanosheets and the second gas source 271 enter the high-pressure respirator to be mixed to form the first mixed gas flow, and then the first mixed gas flow and the second gas source 271 enter the second jet mill 19 at the same time; because of the difference of the air flows, the graphite in the first jet mill 3 moves by the power of the first air source 101, the graphene nanosheet in the second jet mill 19 is mixed with the second air source, the graphene nanosheet has a main power, and is mixed with the second air source 271 again on the basis, so that the friction speed can be increased, and meanwhile, the graphene nanosheet has the main power, so that the graphene nanosheet moves at the middle position of the second jet mill 19, the collision with the inner wall of the second jet mill 19 is reduced, and the integrity of the grid structure is ensured as much as possible.

2. The airflow velocity is different, the airflow velocity of the first airflow mill 3 is 300-800 m/s, the airflow velocity is supersonic speed high speed airflow, the first abrasive particles and graphite impact at high speed, the impact force enables the graphite particles to be rapidly converted into paper-shaped graphene nanosheets, the airflow velocity of the second airflow mill 19 is 50-400 m/s, the friction impact force is adopted, van der Waals force between graphene layers is overcome, the integrity of a grid structure is guaranteed to the greatest extent, and high quality graphene is produced.

3. The raw materials are different, the raw material of the first jet mill 3 is graphite, the thickness of the graphite is more than 1000 nanometers, and the graphite belongs to granular brittle materials. The graphene nanosheet as the raw material of the second jet mill 19 is a paper-shaped nanomaterial with the thickness of less than 500 nanometers, is not impact-resistant and is easy to tear.

4. The used airflow accelerators are different, the first airflow accelerator 2 used by the first airflow mill 3 uses a Laval nozzle, the airflow speed is constant and inconvenient in work, the second airflow accelerator 18 used by the second airflow mill 19 uses an adjusting valve, the speed can be dynamically adjusted in work, and the integrity of the graphene grid structure is ensured by adjusting the airflow speed.

A PLC control system can be introduced according to the requirement, and automation of the production process is realized.

The invention also provides a method for preparing graphene by adopting the equipment for preparing graphene, which comprises the following steps:

s1, introducing a first air source 101 into a first air compressor 102, pressurizing through the first air compressor 102 to enable the air source pressure to be 0.3-0.8 MPa, then entering a first dryer 103, removing moisture in the first air source 101 through the first dryer 103 to ensure that the relative humidity is lower than 30%, and further entering a first air storage tank 104, wherein the first air storage tank 104 can provide an air source with relatively stable pressure for a first airflow accelerator 2, graphite, the first air source 101 and first abrasive particles are mixed in a first airflow mill 3 to form mixed air flow, and the mixed air flow speed after being accelerated by the first airflow accelerator 2 reaches 300-800 m/S; the graphite is selected from one or more of crystalline flake graphite, expandable graphite, expanded graphite, graphite oxide, modified graphite, intercalated graphite, graphite nanosheets, aphanitic graphite, dense crystalline graphite and artificial graphite.

S2: introducing the mixed gas flow into a first classifier 5, wherein the first classifier 5 is rotated at a speed of 2000-10000 r/min, graphite and first abrasive particles are separated in the first classifier 5, so that graphene nanosheets are obtained, the thickness of the graphene nanosheets is 200-500 nm, the graphene nanosheets are collected in a graphene nanosheet collecting bin 10, and the graphene nanosheets are conveyed to a transition bin 13 through a conveyor 28.

Referring to fig. 2, in the two steps S1 and S2, the graphene nanoplatelets are produced, the thickness of the graphite is greater than 1000nm, high-speed airflow with high sound velocity is generated at the increased velocity of the first airflow accelerator 2, the high-speed airflow velocity is 300-800 m/S, the first abrasive particles in the first abrasive particle bin 4 collide with the graphite at high velocity, the graphite is rapidly converted into the graphene nanoplatelets, and the thickness of the produced graphene nanoplatelets is 200-500 nm. Because the continuous feeding is generated, the continuous discharging can be realized, and the yield is high.

S3, enabling the graphene nanosheets in the transition bin 13 to enter a high-pressure respirator 17 through a second feeder 14, meanwhile, connecting a second air source 271 into the high-pressure respirator 17, leading the second air source 271 into a second air compressor 272, boosting the pressure through the second air compressor 272 to enable the air source pressure to be 0.3-0.8 MPa, then, enabling the graphene nanosheets to enter a second dryer 273, removing moisture in the second air source 271 through the second dryer 273, ensuring that the relative humidity is lower than 30%, and further enabling the graphene nanosheets to enter a second air storage tank 274, enabling the first air storage tank 104 to provide an air source with relatively stable pressure for the high-pressure respirator 17, and mixing the graphene nanosheets and the second air source 271 in the high-pressure respirator 17 to form first mixed air flow;

s4, opening a second air valve 31, enabling the first mixed air to flow through a second airflow accelerator 18 to accelerate, then entering a second airflow mill 19, and rubbing with second abrasive particles in the second airflow mill 19 to form a first graphene airflow mixture;

s5: the first graphene airflow mixture in the S4 is connected into a second classifier 20, the rotating speed of the second classifier 20 is 1000-5000 r/min, second abrasive particles and graphene are separated through the machine, centrifugal force is generated by rotation, the abrasive particles are thick and large in centrifugal force, under the action of the centrifugal force and the self gravity of the second classifier 20, the abrasive particles are thrown to the four walls and settled, the abrasive particles return to a second airflow mill 19 to be continuously recycled, and the graphene and the abrasive particles are separated; the graphene passes through a grader device under the drive of negative pressure airflow and enters the next procedure, and the grader is used for separating second abrasive particles from the graphene to obtain primary graphene;

s6, enabling the primarily-prepared graphene to enter a high-pressure respirator 17 through a transition collector 15, mixing the primarily-prepared graphene with a second air source 271 again to form a second mixed air flow, enabling the second mixed air flow to enter a second air flow mill 19 after being accelerated by a second air flow accelerator 18, enabling the second mixed air flow to rub with second abrasive particles in the second air flow mill 19 mutually to form a second graphene air flow mixture, enabling the second graphene air flow mixture to be connected into a second classifier 20, enabling the rotating speed of the second classifier 20 to be 1000-5000 r/min, enabling the abrasive particles and the graphene to be separated, and obtaining secondary-prepared graphene.

S7: repeating the step S6 for N times to obtain a graphene finished product, wherein N is 1-200, and the single cycle working time is 1-30 min; the larger the N, the thinner the thickness of the graphene, and the easier the graphene is to be torn. The selected graphite types are different, the value of single-layer graphene N is 50-200, the value of few-layer graphene N is 5-100, the value of multi-layer graphene N is 1-30, graphene passes through the second classifier 20 device under the drive of negative pressure airflow, and before N times, the third air valve 32 is opened and enters the channel of the transition collector 15;

and S8, the finished graphene product is connected into the graphene collecting bin 24 and packaged by the packaging machine 22 to obtain the finished graphene product.

Referring to fig. 3, S3-S8 illustrate that the produced graphene nanoplatelets are used to prepare graphene finished products, and although there are many types of existing graphene nanoplatelets, they are expensive, meanwhile, the adaptability is poor, the quality of the produced graphene finished product is not ideal, in order to overcome the problem, the inventor carries out pre-treatment on the existing graphite (the thickness is more than 1000nm), the pre-treatment refers to the process flow in figure 2, the pre-material (namely the graphene nano-sheet) suitable for producing the graphene finished product is produced, meanwhile, the pretreatment can be applied to various graphites (the thickness is more than 100nm), such as one or more of crystalline flake graphite, expandable graphite, expanded graphite, oxidized graphite, modified graphite, intercalated graphite, graphite nanosheets, aphanitic graphite, dense crystalline graphite and artificial graphite, wherein the particle size of the graphite ranges from 1um to 10mm, and preferably ranges from 100um to 3 mm. The raw material cost is reduced, and simultaneously, the produced graphene finished product has good quality.

The invention also provides the graphene prepared by the equipment and the method, and single-layer graphene and few-layer graphene can be obtained due to different numerical values of N, wherein the thickness of the single-layer graphene is less than 0.6nm, the thickness of the few-layer graphene is less than 5nm, and the thickness of the multiple-layer graphene is less than 100 nm; in particular, the single-layer graphene in the present invention refers to a two-dimensional carbon material composed of a layer of carbon atoms periodically and closely packed in a benzene ring structure; the few-layer graphene refers to a two-dimensional carbon material formed by stacking 2-10 layers of carbon atoms which are periodically and closely stacked in a benzene ring structure (namely a hexagonal honeycomb structure) in different stacking modes; the multilayer graphene also refers to a two-dimensional carbon material formed by stacking carbon atoms with thickness of more than 10 layers and less than 100nm, wherein the carbon atoms are periodically and closely stacked in a benzene ring structure in different stacking modes.

Example 1

Flake graphite with the particle size of 200um and the pressure of a first air source of 0.6MPa is selected, and the airflow speed is 360m/S after the speed is increased by a first airflow speed increasing machine. The first abrasive particles are made of diamond micro powder with the particle size of 22-36 um; the first jet mill is a flat jet mill, the rotating speed of the first classifier is 4000r/min, and crystalline flake graphene nanosheets are generated, and the thickness of the crystalline flake graphene nanosheets is 400-500 nanometers.

And selecting the flake graphene nanosheets, adjusting the pressure of a second air source to be 0.6MPa, accelerating by a second airflow speed accelerator, wherein the airflow speed is 250m/S, the second abrasive particles are 22-36 um in particle size and are made of diamond micropowder, the rotating speed of a second classifier is 2000r/min, the cycle number N is 2, and the single cycle time of N is 9 minutes, so that multilayer graphene is obtained, wherein the thickness of the multilayer graphene is 20-25 nm.

Example 2

Flake graphite with the particle size of 200um and the pressure of a first air source of 0.6MPa is selected, and the airflow speed is 360m/S after the speed is increased by a first airflow speed increasing machine. The first abrasive particles are made of diamond micro powder with the particle size of 22-36 um; the first jet mill is a flat jet mill, the rotating speed of the first classifier is 5000r/min, and crystalline flake graphene nanosheets are generated, and the thickness of the crystalline flake graphene nanosheets is 300-400 nanometers.

And selecting the flake graphene nanosheets, adjusting the pressure of a second air source to be 0.6MPa, accelerating by a second airflow accelerating machine, wherein the airflow flow rate is 200m/S, the second abrasive particles are 22-36 um in particle size and are made of diamond micropowder, the rotating speed of a second classifier is 2000r/min, the cycle number N is 15, and the single cycle time of N is 6 minutes, so that few-layer graphene is obtained, and the thickness of the few-layer graphene is 3-5 nm.

Example 3

Flake graphite with the particle size of 200um and the pressure of a first air source of 0.6MPa is selected, and the airflow speed is 360m/S after the speed is increased by a first airflow speed increasing machine. The first abrasive particles are made of diamond micro powder with the particle size of 22-36 um; the first jet mill is a flat jet mill, the rotating speed of the first classifier is 7000r/min, and crystalline flake graphene nanosheets are generated, and the thickness of the crystalline flake graphene nanosheets is 250-300 nanometers.

And selecting the flake graphene nanosheets, adjusting the pressure of a second air source to be 0.6MPa, accelerating by a second airflow speed accelerator, wherein the airflow speed is 150m/S, the second abrasive particles are 22-36 um in particle size and are made of diamond micropowder, the rotating speed of a second classifier is 2000r/min, the cycle number N is 100, and the single cycle time of N is 6 minutes, so that the single-layer graphene is obtained, and the thickness of the single-layer graphene is 0.3-0.8 nm.

Example 4

Expanded graphite with the particle size of 2mm and the first gas source pressure of 0.6MPa is selected, and the airflow speed is increased by a first airflow speed increasing machine to 360 m/S. The first abrasive particles are made of diamond micro powder with the particle size of 22-36 um; the first jet mill is a flat jet mill, the rotating speed of the first classifier is 5000r/min, and the expanded graphene nanosheet is generated, and the thickness of the expanded graphene nanosheet is 250-400 nanometers.

And selecting the expanded graphene nanosheet, adjusting the pressure of a second air source to be 0.6MPa, accelerating by a second airflow speed accelerator, wherein the airflow speed is 250m/S, the particle size of the second abrasive particle is 22-36 um, the material is diamond micropowder, the rotating speed of a second classifier is 2000r/min, the cycle number N is 2, and the single cycle time of N is 9 minutes, so that the multilayer graphene is obtained, and the thickness of the multilayer graphene is 15-20 nm.

Example 5

Expanded graphite with the particle size of 2mm and the first air source pressure of 0.5-0.7 MPa is selected, and the airflow speed is increased by a first airflow speed increasing machine to 360 m/S. The first abrasive particles are made of diamond micro powder with the particle size of 22-36 um; the first jet mill is a flat jet mill, the rotating speed of the first classifier is 6000r/min, and the expanded graphene nanosheet is generated, and the thickness of the expanded graphene nanosheet is 250-300 nanometers.

And selecting the expanded graphene nanosheet, adjusting the pressure of a second air source to be 0.6MPa, accelerating by a second airflow speed accelerator, wherein the airflow speed is 200m/S, the particle size of the second abrasive particle is 22-36 um, the material is diamond micropowder, the rotating speed of a second classifier is 2000r/min, the cycle number N is 20, and the single cycle time of N is 120 minutes, so that few-layer graphene is obtained, and the thickness of the few-layer graphene is 1.5-3 nm.

Example 6

Expanded graphite with the particle size of 2mm and the first gas source pressure of 0.6MPa is selected, and the airflow speed is increased by a first airflow speed increasing machine to 360 m/S. The first abrasive particles are made of diamond micro powder with the particle size of 22-36 um; the first jet mill is a flat jet mill, the rotating speed of the first classifier is 7000r/min, and the expanded graphene nanosheet is generated, and the thickness of the expanded graphene nanosheet is 200-250 nanometers.

And selecting the expanded graphene nanosheet, adjusting the pressure of a second air source to be 0.6MPa, accelerating by a second airflow speed accelerator, wherein the airflow speed is 150m/S, the particle size of the second abrasive particle is 22-36 um, the material is diamond micropowder, the rotating speed of a second classifier is 2000r/min, the cycle number N is 100, and the single cycle time of N is 6 minutes, so that the single-layer graphene is obtained, and the thickness of the single-layer graphene is 0.3-0.8 nm.

The invention has been described above with reference to the accompanying drawings, it is obvious that the invention is not limited to the specific implementation in the above-described manner, and it is within the scope of the invention to apply the inventive concept and solution to other applications without substantial modification.

Claims (3)

1. The utility model provides an equipment of preparation graphite alkene, its characterized in that, includes first air intake unit, first air intake unit connects first air current accelerator, first air current accelerator is connected first jet mill, first jet mill still is connected with first feeding machine, first mill grain storehouse, first grader respectively, first grader is connected with graphite alkene nanometer piece collecting bin, graphite alkene nanometer piece collecting bin passes through the conveyer and connects the transition storehouse, the transition storehouse passes through second feeding machine and connects high pressure respirator, high pressure respirator still is connected with second air intake unit, transition collector, second air current accelerator, exhaust apparatus, the second air intake unit still connects the one end of second air current accelerator, the other end of second air current accelerator is connected the second jet mill, the second jet mill still is connected with second grader, The second classifier is also connected with a transition collector and a graphene collecting bin;

the first feeding machine is also connected with a raw material bin, a first environment dust hood is installed at the top of the raw material bin, the first environment dust hood is connected with an environment dust remover, and the environment dust remover is also connected with a second environment dust hood;

the graphene nanosheet collecting bin is also connected with one end of a first dust remover, and the other end of the first dust remover is connected with a first fan; the graphene collecting bin is further respectively connected with a packaging machine and a packaging machine dust remover, a packaging machine dust hood is mounted on the packaging machine, the packaging machine dust hood is further connected with one end of the packaging machine dust remover, and the other end of the packaging machine dust remover is connected with a second fan;

the first air inlet unit comprises a first air storage tank, a first dryer, a first air compressor and a first air source, one end of the first air storage tank is connected with the first airflow accelerator, the other end of the first air storage tank is connected with one end of the first dryer, the other end of the first dryer is connected with one end of the first air compressor, the other end of the first air compressor is connected with the first air source, and the first air source is any one of air, argon, nitrogen and carbon dioxide;

the second air inlet unit comprises a second air storage tank, a second dryer, a second air compressor and a second air source;

the high-pressure respirator is respectively connected with a second gas storage tank and the second jet mill through gas pipes; the air pipe comprises a first air pipe and a second air pipe, one end of the first air pipe is connected with the high-pressure respirator, the other end of the first air pipe is connected with the middle position of the second air pipe, the left end of the second air pipe is connected with the second airflow accelerator, the right end of the second air pipe is connected with the second air storage tank, a second air valve is installed on the left side of the middle position of the second air pipe, and a first air valve is installed on the right side of the middle position of the second air pipe;

still include first butterfly valve, second butterfly valve, first butterfly valve one end is passed through the pipe connection high pressure breathing machine, the other end passes through the pipe connection the second feeding machine, second butterfly valve one end is passed through the pipe connection the second grader, the other end passes through the pipe connection the transition collector.

2. The apparatus according to claim 1, wherein one end of the second gas tank is respectively connected to the high-pressure ventilator and the second gas flow accelerator, the other end of the second gas tank is connected to one end of the second dryer, the other end of the second dryer is connected to one end of the second air compressor, the other end of the second air compressor is connected to the second gas source, and the second gas source is any one of air, argon, nitrogen and carbon dioxide.

3. A method for preparing graphene, which is characterized in that the method for preparing graphene according to any one of claims 1-2 is adopted, and comprises the following steps:

s1, mixing graphite with a first gas source and first abrasive particles in a first jet mill to form mixed gas flow, wherein the graphite is selected from one or more of crystalline flake graphite, expandable graphite, expanded graphite, oxidized graphite, modified graphite, intercalated graphite, graphite nanosheets, aphanitic graphite, dense crystalline graphite and artificial graphite;

s2: introducing the mixed gas flow in the S1 into a first classifier, wherein the rotating speed of the first classifier is 2000-10000 r/min, and separating graphite from first abrasive particles in the first classifier to obtain a graphene nanosheet, wherein the thickness of the graphene nanosheet is 200-500 nm;

s3, introducing the graphene nanosheets in the S2 into a high-pressure respirator, simultaneously accessing a second gas source into the high-pressure respirator, and mixing the graphene nanosheets and the second gas source in the high-pressure respirator to form a first mixed gas flow;

s4, enabling the first mixed gas to enter a second jet mill after being accelerated by a second jet accelerator, and enabling the first mixed gas to rub with second abrasive particles in the second jet mill to form a first graphene jet mixture;

s5: the first graphene airflow mixture in the S4 is connected into a second classifier, the rotating speed of the second classifier is 1000-5000 r/min, abrasive particles and graphene are separated, and primary graphene is obtained;

s6, enabling the primarily-prepared graphene to enter a high-pressure respirator through a transition collector, mixing the primarily-prepared graphene with a second air source again to form a second mixed air flow, enabling the second mixed air flow to enter a second jet mill after the second mixed air flow is accelerated through a second air flow accelerator, enabling the second mixed air flow to rub with second abrasive particles in the second jet mill to form a second graphene air flow mixture, enabling the second graphene air flow mixture to be connected into a second classifier, enabling the rotation speed of the second classifier to be 1000-5000 r/min, and enabling the abrasive particles and the graphene to be separated to obtain secondary-prepared graphene;

s7: repeating the step S6 for N times to obtain a primary graphene finished product, wherein N is 1-200, and the single cycle working time is 1-30 min;

and S8, putting the finished graphene product into a graphene collecting bin, and packaging by a packaging machine to obtain the finished graphene product.

Images