CN114014307A - Preparation method of few-layer cryptocrystalline graphene - Google Patents
Preparation method of few-layer cryptocrystalline graphene Download PDFInfo
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Abstract
The invention provides a low-cost batch preparation method of few-layer cryptocrystalline graphene, and the few-layer cryptocrystalline graphene with high carbon content is obtained through a brand-new liquid phase stripping process.
Description
Technical Field
The invention relates to a flotation method of a preparation method of few-layer aphanitic graphene, and belongs to the field of graphene preparation.
Background
Graphene (Graphene) is sp2The hybridized and connected carbon atoms are tightly packed into the thinnest and hardest nano material with a single-layer two-dimensional honeycomb lattice structure, the nano material is almost completely transparent and only absorbs 2.3 percent of light, the acting force among the carbon atoms in the graphene is very strong, even if the surrounding carbon atoms are crushed and collided at normal temperature, the interference on electrons in the graphene is very small, the electron mobility exceeds 15000cm 2/V.s at normal temperature, the movement speed of the electrons reaches 1/300 of the light speed, the carbon is higher than that of a nanotube or a silicon crystal, and the resistivity is only about 106 omega.cm and lower than that of copper and silver. Therefore, the graphene has excellent optical, electrical and mechanical properties, has important application prospects in the aspects of materials science, micro-nano processing, energy, biomedicine, drug delivery and the like, and is considered to be a revolutionary material in the future. The common production methods of graphene are mechanical stripping method, oxidation intercalation re-reduction method and SiC epitaxial growth method, and the production methods of thin films are chemical vapor deposition method, liquid phase stripping method, mechanical stripping method, liquid phase mechanical stripping method and the like, wherein the chemical vapor deposition method can obtain high-quality graphene, but has low yield, high requirement on a substrate and high transfer storage capacityIn the extreme difficulties; the oxidation intercalation re-reduction method can realize the mass production of graphene, but the structure of the graphene is damaged in the oxidation process, so that a high-quality graphene product is difficult to obtain, a large amount of concentrated sulfuric acid is required for the oxidation intercalation, and the waste acid is huge and difficult to treat; the liquid phase exfoliation method dissociates the graphite sheet layer in a suitable solvent by using ultrasonic energy, however, the liquid phase exfoliation method for preparing graphene has the problem that the residual solvent is difficult to remove, and the solvent exfoliation yield is generally low. In contrast, the liquid-phase mechanical physical exfoliation method is a reliable and easy-to-implement method that can produce high-quality graphene at low cost. The intercalation agent is a commonly used stripping aid in a liquid-phase mechanical physical stripping method, however, most of inorganic intercalation agents in the prior art are soluble salts or surfactants, the inorganic intercalation agents mainly play a role in adjusting the surface tension of aqueous solution, and the intercalation agents are easy to remain in graphene after the preparation process of the graphene is completed and affect the quality of the graphene.
Patent publication No. CN113443620A provides a method for obtaining few-layer graphene nano dispersion liquid by adding expanded graphite and ethylene glycol into inorganic intercalation liquid to carry out stirring pre-dispersion, high-speed shearing and high-pressure stripping; the selected inorganic intercalation agent is one or more of nano gas-phase silicon dioxide, superfine barium sulfate, nano calcium carbonate, nano titanium dioxide, nano iron oxide, nano zirconium oxide, nano zinc oxide, spherical aluminum oxide, carbon black and carbon nano tubes. However, the intercalator is difficult to separate when being adsorbed in aphanitic graphite, so that the final graphene quality is greatly influenced, and the use of the organic dispersant influences the electric conduction and heat conduction performance of the graphene, so that the application of the intercalator in a conductive material or the application of the graphene in a lead storage battery is influenced.
Disclosure of Invention
The first purpose of the invention is to provide a preparation method of few-layer graphene. The method can prepare the few-layer aphanitic graphene with high carbon content at low cost.
A preparation method of few-layer cryptocrystalline graphene comprises the following steps:
s1, adding water into 100-mesh and 200-mesh aphanitic graphite powder with fixed carbon content of 40-80% to prepare ore pulp with concentration of 30 wt%, adding an intercalator, and performing first-stage ore grinding to obtain slurry I;
s2, diluting the slurry I to 10 wt%, adding a foaming agent, a collecting agent, an inhibitor and an anionic surfactant, and performing first open-circuit flotation to obtain slurry II;
s3, concentrating the slurry II to 25 wt%, adding an intercalant, and performing second-stage ore grinding; then diluting the slurry II to 23 wt%, adding an intercalation agent, and then carrying out third-stage ore grinding to obtain slurry III;
s4, diluting the slurry III to 8 wt%, adding a foaming agent, a collecting agent, an inhibitor and an anionic surfactant, and performing second open-circuit flotation to obtain slurry IV;
s5, concentrating the slurry IV to 21 wt%, adding an intercalant, and grinding in the fourth stage; then diluting the slurry IV to 19 wt%, adding an intercalating agent, and performing fifth-stage ore grinding to obtain slurry V;
s6, diluting the slurry V to 8 wt%, adding a foaming agent, a collecting agent, an inhibitor and an anionic surfactant, and performing third open-circuit flotation to obtain slurry VI;
s7, concentrating the slurry IV to 17 wt%, adding an intercalation agent and a grinding aid, and performing sixth stage ore grinding; then diluting the slurry II to 15 wt%, adding an intercalation agent, and carrying out seventh stage ore grinding to obtain a slurry VII;
s8, diluting the slurry VII to 6 wt%, adding a foaming agent, a collecting agent, an inhibitor and an anionic surfactant, performing fourth open circuit flotation, diluting the slurry III to 6 wt%, adding the collecting agent and the anionic surfactant, and performing fifth open circuit flotation to obtain slurry VIII;
s9, performing pressure filtration on the slurry VIII and drying to obtain flotation concentrate, and purifying the flotation concentrate by adopting an acid-base method to obtain few-layer graphene with the carbon content higher than 99.5%;
the intercalating agent comprises sodium hydroxide or potassium hydroxide.
S1, adding water into 100-mesh aphanitic graphite powder with the fixed carbon content of 40-80% and the material diameter of 200 meshes, mixing the mixture to obtain ore pulp with the concentration of 30 wt%, adding 8kg of an intercalation agent into the ore pulp by each ton of aphanitic graphite powder, grinding the ore pulp in a wet grinding machine at the ore pulp feeding speed of 28L/min and the linear speed of 10 m/S, and grinding the ore pulp in a first stage to obtain slurry I;
and S2, diluting the slurry I to 10 wt%, adding 1.5kg of foaming agent, 0.8kg of collecting agent, 5kg of inhibitor and anionic surfactant into each ton of cryptocrystalline graphite powder, and performing first open-circuit flotation to obtain slurry II.
S3, concentrating the slurry II to 25 wt% of ore pulp, adding 5kg of intercalation agent into the ore pulp by taking cryptocrystalline graphite powder per ton, grinding in a wet mill at the ore pulp feeding speed of 28L/min and the linear speed of 10 m/S, and grinding in a third section to obtain slurry III;
and S4, diluting the slurry III to 8 wt%, adding 1kg of foaming agent, 0.5kg of collecting agent, 5kg of inhibitor and 2kg of anionic surfactant into each ton of cryptocrystalline graphite powder, and performing second open-circuit flotation to obtain slurry IV.
S5 is that after concentrating the slurry IV to 21 wt% ore pulp, adding 3kg of intercalation agent into the ore pulp by taking cryptocrystalline graphite powder per ton, grinding in a wet mill, wherein the feeding speed of the ore pulp of the mill is 28L/min, the linear speed is 10 m/S, and grinding in the fourth stage is carried out; and then diluting the slurry IV to 19 wt%, adding 1kg of intercalation agent into each ton of cryptocrystalline graphite powder, and grinding the slurry V in the fifth section to obtain the slurry V.
And S6 is slurry V, after the slurry V is diluted to 8 wt%, adding 1kg of foaming agent, 0.5kg of collecting agent, 5kg of inhibitor and 2kg of anionic surfactant into each ton of cryptocrystalline graphite powder, and then carrying out third open flotation to obtain slurry VI.
S7 is that after slurry VI is concentrated to 17 wt% ore pulp, 5kg of intercalation agent and 20kg of grinding aid are added into the ore pulp by each ton of cryptocrystalline graphite powder for grinding in a wet grinding machine, the feeding speed of the ore pulp of the grinding machine is 28 liters/minute, the linear speed is 10 meters/second, and the sixth stage of grinding is carried out; and then diluting the slurry VI to 15 wt%, adding 2kg of intercalation agent into each ton of cryptocrystalline graphite powder, and grinding the ore at the seventh stage to obtain the slurry VII.
And S8, diluting the slurry VII to 6 wt%, adding 1kg of foaming agent, 0.5kg of collecting agent, 5kg of inhibitor and 2kg of anionic surfactant into each ton of aphanitic graphite powder, and performing open-circuit flotation to obtain the slurry VIII.
The ore grinding adopts a grinding machine comprising a wet grinding machine;
the wet mill comprises a vertical stirring mill, a sand mill or a curved mill;
the grinding aid comprises a ceramic grinding aid;
the ceramic grinding aid can be sieved by a 30-mesh sieve;
the Mohs hardness of the ceramic grinding aid is more than or equal to 6.5;
the ceramic grinding aid comprises alumina, zirconia, silicon carbide or silicon nitride;
the filter pressure of the filter pressing is 0.6MPAa, and the squeezing pressure is 1.2 MPAa;
the drying temperature is 320-350 ℃.
The acid-base method comprises the steps of adding sodium hydroxide with the mass being 3 times of that of impurities in flotation concentrate into the flotation concentrate, roasting at 750 ℃, and rinsing under acidic conditions.
The application of the few-layer graphene is applied to being used as an electrode negative electrode material or a wave-absorbing material.
Compared with the prior art, the invention has the following beneficial effects:
the method can prepare the few-layer graphene, wherein the thickness of a few-layer graphene sheet is 1.2-1.8 nm, the size of the graphene sheet is 0.5-5 mu m, and the number of the graphene sheets is 3-5. The few-layer cryptocrystalline graphene powder produced by the method is low in production cost and can be prepared massively, and the prepared few-layer cryptocrystalline graphene has good low-temperature discharge performance and can be used for positive and negative electrodes of batteries and conductive and heat-conducting materials.
Drawings
Fig. 1 shows a TEM photograph of the few-layer cryptocrystalline graphene prepared in example 1. As can be seen from the figure, the overall morphology of the graphene is in a transparent gauze shape. Although the thickness of the graphene cannot be accurately characterized, the graphene sheet layer is extremely thin as judged by the transparent gauze shape at the edge of the graphene and the width of the edge tilting.
Fig. 2 shows AFM photographs and analysis results of few-layered cryptocrystalline graphene prepared in example 1. AFM is one of the most effective methods for measuring the thickness of nanomaterials. The graphene shown in fig. 2 is a graphene sheet with a thickness of 1.5 nm. Due to thermodynamic fluctuations and the influence of oxygen-containing functional groups on graphene, the thickness of single-layer graphene is generally about 0.7nm, which indicates that the number of layers of graphene prepared in example 1 is 2-3.
Fig. 3 shows a raman spectrum of the few-layer cryptocrystalline graphene prepared in example 1. Raman spectrum analysis is the simplest and most effective method for testing graphene, and the reflected electronic structure and the interaction between electrons can quickly and qualitatively judge the quality and the number of layers of the graphene.
According to empirical formulas:
N＝I2D/IG
wherein I2D，IGIntensity of 2D peak and G peak, respectively, when N is>1, the graphene is a single layer; when N is approximately equal to 1, the graphene is a double layer; when N is present<1, the graphene is multilayered. N of the three varieties of graphene powder of the item is less than 1 through Raman analysis, which indicates that the prepared graphene is multilayer.
Fig. 4 shows a BET-BJH curve of the few-layer cryptocrystalline graphene prepared in example 1. From; it can be seen that the langmuir surface area of the graphene sheet of the few-layer cryptocrystalline graphene prepared in example 1 was 50.3m2/g。
Detailed Description
Example 1
S1, grinding 1 ton of aphanitic graphite raw ore with 40-80% fixed carbon into 100-200-mesh powder by using a Raymond mill, mixing the powder in a stirring barrel until the concentration of ore pulp is 30%, adding 8kg of sodium hydroxide into the ore pulp, uniformly stirring the mixture and the ore pulp, and feeding the mixture into a vertical stirring mill to carry out first-stage grinding to obtain slurry I; the mill feed rate was 28 liters pulp/min and the line speed was 10 m/s.
S2, diluting the slurry I to 10 wt% with water, adding 1.5kg of octanol, 0.8kg of kerosene, 5kg of water glass and 2kg of sodium hexametaphosphate to perform first full open flotation, and ensuring that the retention time of ore pulp in a flotation tank is not less than 40 minutes during flotation to obtain slurry II.
S3, performing filter pressing on the slurry II through a plate-and-frame filter press, adjusting the water content of a filter cake to be about 60%, adjusting the filter cake of the plate-and-frame filter press and part of the slurry II to be 25%, then placing the filter cake in a vertical stirring mill to perform second-stage grinding, taking 1000L vertical stirring mill as an example, the feeding speed of the mill is 28L ore pulp/min, the linear speed of the mill is 10 m/S, adding 5kg of sodium hydroxide during second-stage grinding to be uniformly stirred during pulp adjusting, diluting the ore pulp after second-stage grinding to be 23% in pulp concentration, simultaneously supplementing 2kg of sodium hydroxide, uniformly stirring the ore pulp and feeding the ore pulp into the vertical stirring mill to perform third-stage grinding, taking 1000L vertical stirring mill as an example, the linear speed of the mill is 10 m/S, and the feeding speed is 28L/S, and obtaining the slurry III.
S4, diluting the slurry III to 8 wt%, adding 1kg of sec-octanol, 0.5kg of kerosene, 5kg of water glass and 2kg of sodium hexametaphosphate, uniformly stirring, and performing second open-circuit flotation to obtain slurry IV. And during flotation, the retention time of the ore pulp in the flotation tank is not less than 40 minutes.
S5, sending a part of the slurry IV (the concentration of the slurry is about 12%) to a plate-and-frame filter press for filter pressing, adjusting the water content of a filter cake to be about 60%, mixing the filter cake of the plate-and-frame filter press with the part of the slurry IV, adjusting the mixture to the concentration of the slurry to be 21%, and then placing the mixture in a vertical stirring mill for grinding the fourth section. The feeding speed of the mill is 28 liters per minute, the linear speed of the mill is 10 meters per second, and 3kg of sodium hydroxide is added during four-stage ore grinding. Diluting the slurry IV to 19 wt%, supplementing 1kg of sodium hydroxide, uniformly stirring, and performing fifth-stage ore grinding to obtain slurry V. The feeding speed and the linear speed of the mill for grinding the fifth section of ore are consistent with those of the fourth section of ore grinding.
S6, diluting the concentration of the slurry V to 8%, adding 1kg of secondary octanol, 0.5kg of trapping agent, 5kg of water glass and 2kg of sodium hexametaphosphate into the diluted slurry, uniformly stirring, and performing third-stage full open-circuit flotation to obtain a slurry VI. And during flotation, the retention time of the ore pulp in the flotation ore is not less than 40 minutes.
S7, performing filter pressing on the part of the slurry VI by using a plate-and-frame filter press, mixing a filter cake and the slurry VI to the concentration of 17% of ore pulp, simultaneously adding 5kg of sodium hydroxide and 20kg of aluminum oxide, uniformly stirring the mixture and the ore pulp, and performing sixth-stage ore grinding, wherein the parameters of the sixth-stage ore grinding are the same as those of the fifth-stage ore grinding; and diluting the slurry VI after the sixth stage of ore grinding with a small amount of water to reach the concentration of 15% of the ore pulp, simultaneously supplementing 2kg of sodium hydroxide, and performing seventh stage of ore grinding after uniformly stirring to obtain a slurry VII. The seventh stage of grinding is the same as the fifth stage of grinding.
S8, adding water into the slurry VII to adjust the concentration of the slurry to 6%, adding 1kg of octanol, 0.5kg of kerosene, 5kg of water glass and 2kg of sodium hexametaphosphate, uniformly stirring, and then performing fourth-stage flotation, wherein the retention time of the slurry in a flotation tank is not less than 40 minutes in the fourth-stage flotation, the retention time of the slurry VII (with the solid content of about 12%) in the flotation tank is adjusted to 6%, the kerosene 0.2kg and the sodium hexametaphosphate are added while the slurry is adjusted, uniformly stirring, then entering a fifth-stage open-circuit flotation, and the retention time of the slurry in the flotation tank is not less than 40 minutes in the fifth-stage open-circuit flotation.
S9, sending the concentrate subjected to five-stage flotation into a membrane filter press for filter pressing, wherein the filter pressure is 0.6MPaa, the press pressure is 1.2MPa, the filter cake after being pressed is sent into a strong dryer for drying, the fuel of the strong dryer is natural gas, the material is dried by a hot blast stove after being directly burned by a burner, the inlet temperature of the dryer is 320-350 ℃, the outlet temperature is 120 ℃, the water content of the dried graphene powder is less than or equal to 1%, the thickness of the dried graphene powder is 1.2-1.8 nm, the size of a lamella is 0.5-5 mu m, the fixed carbon content is more than or equal to 92%, and the volatile matter is less than or equal to 2.5%. If the graphene powder needs to be purified to the fixed carbon content of more than or equal to 99.5%, further purifying by an alkaline-acid method.
The cryptocrystalline graphene powder produced from raw ore by the process has the fixed carbon content of only 92 percent, the volatile matter content of about 2.5 percent and other impurities of 5.5 percent (mainly quartz and silicate minerals), can only be used in the rubber industry, the electric conduction and heat conduction coating and the modified asphalt industry, and needs to be further purified if being used in the fields of battery anode and cathode materials and other high-end materials, wherein the simplest method is an alkaline-acid method which comprises the following steps:
(1) adding caustic soda flakes according to the impurity content of 3 times, namely adding 165kg of caustic soda flakes (NaOH) into each ton of caustic soda flakes, uniformly mixing by using a vortex ring mill, then sending the mixture into a large-scale gas-fuel furnace for roasting (introducing nitrogen gas), wherein the roasting kiln is divided into four regions, namely a preheating region, a heating region, a roasting region and a cooling region, the temperature in the roasting region is 750 ℃, the passing time of an object in the roasting region is kept for 20 minutes, the roasted material is cooled to below 100 ℃ by cooling screws, then sending the roasted material into a stirring barrel for leaching, the temperature during leaching is 60 ℃, the leaching time is one hour after reaching 60 ℃, the concentration of ore pulp during leaching is 8-10%, the ore pulp after leaching is sent to a diaphragm filter press for first-pressing, the pressure of the ore pulp after first-pressing is 0.6MPa, the pressure of the ore pulp after pressing is 1.2kg, the filter cake after pressing is sent to the stirring barrel for first-stage rinsing, heating by using steam for first-stage rinsing, keeping the temperature and stirring for 20 minutes, and then entering a second stage, the two-stage filter pressing is a diaphragm filter press, the filtering pressure is 0.6MPa, the squeezing pressure is 1.2MPa, the filter cake after squeezing enters a stirring barrel for two-stage rinsing, steam is needed to be heated to 60 ℃ during rinsing, stirring is carried out for 10 minutes, then three-stage filter pressing is carried out, the filter cake after three-stage filter pressing is 0.6MPa, the squeezing pressure is 1.2MPa, the filter cake after filter pressing is sent to the next stage process, the filter cake after filter pressing is sent to a comprehensive treatment system, the filter cake after two-stage filter pressing is sent for leaching, and the filter cake after three-stage filter pressing is sent to one-stage rinsing for use. The main purpose of the process is to leach and rinse the low modulus sodium silicate formed by NaOH, quartz and silicate in the roasting process.
(2) Adding 100kg of 30% hydrochloric acid into filter cakes obtained after two-stage rinsing and filter pressing according to the dry weight of each ton of graphene powder, leaching, removing alkali metals formed during roasting of the graphene powder and NaOH, heating to 60 ℃ by using steam during leaching, keeping the temperature of 60 ℃ for leaching for one hour, wherein the concentration of leached ore pulp is 8-10%, sending the leached ore pulp to a membrane filter press for first-stage filter pressing, wherein the filtering pressure of the first-stage filter pressing is 0.6MPa, the pressing pressure is 1.2MPa, sending the filter cakes obtained after the first-stage filter pressing to a stirring barrel for first-stage rinsing, the concentration of the ore pulp is 8% during rinsing, using water as rinsing liquid, heating to 60 ℃ by using steam during rinsing, stirring for 20 minutes, sending the filter cakes to the membrane filter press for second-stage filter pressing, wherein the filtering pressure and the pressing force of the second-stage filter pressing are the same as those of the first stage, heating to 60 ℃ by using steam during the second-stage rinsing, keeping the temperature, stirring and rinsing for 20 minutes, and the concentration of the ore pulp is 8%, and (4) conveying the rinsed ore pulp to a diaphragm filter press for filter pressing, and performing the next working procedure on filter cakes after filter pressing. The first stage filter pressing water is sent to a comprehensive treatment system, the second stage filter pressing water is returned to leach and size mixing, and the third stage filter pressing water is sent to the first stage for rinsing.
(3) Sending the three-section filter-pressing filter cake to a powerful dryer for drying, wherein the drying fuel is natural gas, directly burning the natural gas by using a burner, heating and drying the materials by using a hot blast stove, wherein the inlet temperature of the dryer is 320-350 ℃, the outlet temperature of the dryer is 120 ℃, after the alkaline-acid method is adopted, the fixed carbon content of the dried graphene powder is more than or equal to 99.5 percent, most of the dried graphene powder enters a cyclone collector, a small amount (about 20 percent) of the dried graphene powder enters a bag dust collector, the graphene powder entering the bag dust collector basically has no re-agglomeration phenomenon and enters a packaging system for packaging, most of the graphene powder in the cyclone collector has relatively high water content and soft agglomeration phenomenon, secondary depolymerization is needed, a depolymerizer selects a vortex ring mill, meanwhile, hot air at 140-150 ℃ is fed into a feeding port through a natural gas hot blast stove, the water content of the depolymerized graphene powder is less than or equal to 0.5%, agglomeration is avoided, and the depolymerized graphene powder is fed into a packaging machine for packaging.
In summary, the above description is only a preferred embodiment of the present invention, but not intended to limit the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A preparation method of few-layer aphanitic graphene is characterized by comprising the following steps:
s1, adding water into 100-mesh and 200-mesh aphanitic graphite powder with fixed carbon content of 40-80% to prepare ore pulp with concentration of 30 wt%, adding an intercalator, and performing first-stage ore grinding to obtain slurry I;
s2, diluting the slurry I to 10 wt%, adding a foaming agent, a collecting agent, an inhibitor and an anionic surfactant, and performing first open-circuit flotation to obtain slurry II;
s3, concentrating the slurry II to 25 wt%, adding an intercalant, and performing second-stage ore grinding; then diluting the slurry II to 23 wt%, adding an intercalation agent, and then carrying out third-stage ore grinding to obtain slurry III;
s4, diluting the slurry III to 8 wt%, adding a foaming agent, a collecting agent, an inhibitor and an anionic surfactant, and performing second open-circuit flotation to obtain slurry IV;
s5, concentrating the slurry IV to 21 wt%, adding an intercalant, and grinding in the fourth stage; then diluting the slurry IV to 19 wt%, adding an intercalating agent, and performing fifth-stage ore grinding to obtain slurry V;
s6, diluting the slurry V to 8 wt%, adding a foaming agent, a collecting agent, an inhibitor and an anionic surfactant, and performing third open-circuit flotation to obtain slurry VI;
s7, concentrating the slurry IV to 17 wt%, adding an intercalation agent and a grinding aid, and performing sixth stage ore grinding; then diluting the slurry II to 15 wt%, adding an intercalation agent, and carrying out seventh stage ore grinding to obtain a slurry VII;
s8, diluting the slurry VII to 6 wt%, adding a foaming agent, a collecting agent, an inhibitor and an anionic surfactant, performing fourth open circuit flotation, diluting the slurry III to 6 wt%, adding the collecting agent and the anionic surfactant, and performing fifth open circuit flotation to obtain slurry VIII;
s9, performing pressure filtration on the slurry VIII and drying to obtain flotation concentrate, and purifying the flotation concentrate by adopting an acid-base method to obtain few-layer graphene with the carbon content higher than 99.5%;
the intercalating agent comprises sodium hydroxide or potassium hydroxide.
2. The method for preparing the few-layer graphene according to claim 1, wherein:
s1, adding water into 100-mesh aphanitic graphite powder with the fixed carbon content of 40-80% and the material diameter of 200 meshes, mixing the mixture to obtain ore pulp with the concentration of 30 wt%, adding 8kg of an intercalation agent into the ore pulp by each ton of aphanitic graphite powder, grinding the ore pulp in a wet grinding machine at the ore pulp feeding speed of 28L/min and the linear speed of 10 m/S, and grinding the ore pulp in a first stage to obtain slurry I;
and S2, diluting the slurry I to 10 wt%, adding 1.5kg of foaming agent, 0.8kg of collecting agent, 5kg of inhibitor and anionic surfactant into each ton of cryptocrystalline graphite powder, and performing first open-circuit flotation to obtain slurry II.
3. The method for preparing the few-layer graphene according to claim 1, wherein:
s3, concentrating the slurry II to 25 wt% of ore pulp, adding 5kg of intercalation agent into the ore pulp by taking cryptocrystalline graphite powder per ton, grinding in a wet mill at the ore pulp feeding speed of 28L/min and the linear speed of 10 m/S, and grinding in a third section to obtain slurry III;
and S4, diluting the slurry III to 8 wt%, adding 1kg of foaming agent, 0.5kg of collecting agent, 5kg of inhibitor and 2kg of anionic surfactant into each ton of cryptocrystalline graphite powder, and performing second open-circuit flotation to obtain slurry IV.
4. The method for preparing the few-layer graphene according to claim 1, wherein:
s5 is that after concentrating the slurry IV to 21 wt% ore pulp, adding 3kg of intercalation agent into the ore pulp by taking cryptocrystalline graphite powder per ton, grinding in a wet mill, wherein the feeding speed of the ore pulp of the mill is 28L/min, the linear speed is 10 m/S, and grinding in the fourth stage is carried out; and then diluting the slurry IV to 19 wt%, adding 1kg of intercalation agent into each ton of cryptocrystalline graphite powder, and grinding the slurry V in the fifth section to obtain the slurry V.
5. The method for preparing the few-layer graphene according to claim 1, wherein:
and S6 is slurry V, after the slurry V is diluted to 8 wt%, adding 1kg of foaming agent, 0.5kg of collecting agent, 5kg of inhibitor and 2kg of anionic surfactant into each ton of cryptocrystalline graphite powder, and then carrying out third open flotation to obtain slurry VI.
6. The method for preparing the few-layer graphene according to claim 1, wherein:
s7 is that after slurry VI is concentrated to 17 wt% ore pulp, 5kg of intercalation agent and 20kg of grinding aid are added into the ore pulp by each ton of cryptocrystalline graphite powder for grinding in a wet grinding machine, the feeding speed of the ore pulp of the grinding machine is 28 liters/minute, the linear speed is 10 meters/second, and the sixth stage of grinding is carried out; and then diluting the slurry VI to 15 wt%, adding 2kg of intercalation agent into each ton of cryptocrystalline graphite powder, and grinding the ore at the seventh stage to obtain the slurry VII.
7. The method for preparing the few-layer graphene according to claim 1, wherein:
and S8, diluting the slurry VII to 6 wt%, adding 1kg of foaming agent, 0.5kg of collecting agent, 5kg of inhibitor and 2kg of anionic surfactant into each ton of aphanitic graphite powder, and performing fifth open-circuit flotation to obtain the slurry VIII.
8. The method for preparing the few-layer graphene according to claim 1, wherein:
the ore grinding adopts a grinding machine comprising a wet grinding machine;
the wet mill comprises a vertical stirring mill, a sand mill or a curved mill;
the grinding aid comprises a ceramic grinding aid;
the ceramic grinding aid can be sieved by a 30-mesh sieve;
the Mohs hardness of the ceramic grinding aid is more than or equal to 6.5;
the ceramic grinding aid comprises alumina, zirconia, silicon carbide or silicon nitride;
the filter pressure of the filter pressing is 0.6MPAa, and the squeezing pressure is 1.2 MPAa;
the drying temperature is 320-350 ℃.
9. The method for preparing the few-layer graphene according to claim 1, wherein:
the acid-base method comprises the steps of adding sodium hydroxide with the mass being 3 times of that of impurities in flotation concentrate into the flotation concentrate, roasting at 750 ℃, and rinsing under acidic conditions.
10. The use of the few-layer graphene of claim 1, wherein:
the material is applied to the anode and cathode materials of lithium batteries, conductive materials, heat conductive materials and wave absorbing materials.
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