CN111302337A - Plasma contact type graphite purification device - Google Patents
Plasma contact type graphite purification device Download PDFInfo
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- CN111302337A CN111302337A CN202010261979.3A CN202010261979A CN111302337A CN 111302337 A CN111302337 A CN 111302337A CN 202010261979 A CN202010261979 A CN 202010261979A CN 111302337 A CN111302337 A CN 111302337A
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 144
- 229910002804 graphite Inorganic materials 0.000 title claims abstract description 140
- 239000010439 graphite Substances 0.000 title claims abstract description 140
- 238000000746 purification Methods 0.000 title claims abstract description 43
- 239000007788 liquid Substances 0.000 claims abstract description 59
- 239000000725 suspension Substances 0.000 claims abstract description 43
- 238000003860 storage Methods 0.000 claims abstract description 18
- 239000012535 impurity Substances 0.000 claims abstract description 15
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 14
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 10
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 5
- 229910052593 corundum Inorganic materials 0.000 claims description 5
- 229910001220 stainless steel Inorganic materials 0.000 claims description 5
- 239000010935 stainless steel Substances 0.000 claims description 5
- 229910001845 yogo sapphire Inorganic materials 0.000 claims description 5
- 238000000034 method Methods 0.000 abstract description 21
- 238000004519 manufacturing process Methods 0.000 abstract description 11
- 230000008569 process Effects 0.000 abstract description 7
- 238000005265 energy consumption Methods 0.000 abstract description 4
- 239000002699 waste material Substances 0.000 abstract description 4
- 239000010865 sewage Substances 0.000 abstract description 3
- 208000028659 discharge Diseases 0.000 description 61
- 239000000463 material Substances 0.000 description 13
- 238000000926 separation method Methods 0.000 description 13
- 239000003989 dielectric material Substances 0.000 description 9
- 238000005516 engineering process Methods 0.000 description 8
- 230000004888 barrier function Effects 0.000 description 7
- 229910052799 carbon Inorganic materials 0.000 description 7
- 239000000047 product Substances 0.000 description 7
- 239000000126 substance Substances 0.000 description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
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- 239000011149 active material Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
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- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/20—Graphite
- C01B32/21—After-treatment
- C01B32/215—Purification; Recovery or purification of graphite formed in iron making, e.g. kish graphite
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract
The invention relates to a plasma contact type graphite purification device, which is used in the technical field of graphite purification. Comprises an oxidation reaction system, a discharge system, a feeding system and a purification system. The oxidation reaction system comprises a plasma reactor and a buffer tank; the discharge system comprises a high-voltage power supply and a grounding device; the feeding system comprises a graphite suspension storage tank, a second feeding valve and a second feeding pump; the purification system comprises a first centrifugal separator, a second centrifugal separator, an impurity tank, an oxidized graphite tank, a graphite storage tank and a reducing agent dissolving tank. The invention has simple structure, easy manufacture and energy saving, does not generate waste liquid in the whole process, does not need sewage treatment and discharge, reduces the cost, protects the environment, and ensures that the high-purity graphite product prepared by the plasma method has good quality, effectively reduces the production energy consumption and reduces the production cost.
Description
Technical Field
The invention belongs to the technical field of graphite purification, and particularly relates to a plasma contact type graphite purification device.
Background
Graphite is an important strategic resource in China, and the resource yield and the storage capacity of the graphite are the first in the world. The graphite material is used as an industrial raw material and has a great significance in special industries, particularly in the high-tech field, such as photovoltaic solar energy, nuclear energy atomic energy, automobile industry, aerospace technology and the like, but the graphite material used in the industries has to be high-purity graphite with carbon content of more than 99.9 percent and even more than 99.99 percent. The purity of a general graphite product cannot meet the requirement of the high-purity graphite industry, so the development and production of a high-purity graphite material become the development trend of the carbon industry at present, and the development of the graphite material to a wider and deeper field is one of the problems to be solved urgently. The graphite can only reach about 97% grade at most by a physical beneficiation method, the graphite grade is difficult to further improve by the physical beneficiation method, and high-carbon and high-purity graphite with the purity of more than 99% is industrially prepared mainly by a high-temperature and chemical method.
The method for purifying the graphite mainly comprises a chemical method and a physical method, wherein a large amount of acid-base waste liquid and polluting chemical substances are generated by applying chemical reagents in the chemical method, so that the method causes great pollution and damage to the environment and human beings and causes great corrosion to equipment. The high-temperature graphite purification technology can only be applied to special industries due to factors such as high cost and the like. Therefore, the main problems of graphite purification in the prior art are mainly corrosion of acid and alkali to equipment and environmental pollution, high energy consumption and high cost, and the main reasons for the problems are caused by the method, so that other approaches or methods need to be considered for solving the existing graphite purification problems.
The gas discharge plasma can realize chemical change and generate high-temperature atmosphere, and is applied to metallurgy, welding and cutting. The discharge plasma can realize the degradation of organic matters, the treatment of pollutants, the sliding arc discharge treatment of textile wastewater and the preparation of NH by gas3Plasma material, arc plasma metallurgy, etc. are examples of plasma to realize chemical change and generate high temperature atmosphere, and discharge plasma can generate active particles with high oxidation and high temperature environment, so that active material (organic matter, inorganic matter or surfactant) is designed to be injected under the action of active particles with high oxidation formed by discharge to generate O3OH active particles with graphite molecules, impurity molecules: (Oxides such as Si, Fe, C u, Al, etc.) are collided, and then graphite is oxidized, interlayer domains are increased, graphite bonds are cleaved, impurities can be separated from graphite oxide by utilizing the difference in specific gravity between the graphite oxide and the impurities, and the graphite oxide is reduced to obtain pure graphite. For this reason, it is necessary to develop a new apparatus for applying the plasma technology to the field of graphite purification technology.
The plasma discharge modes are various, and people research the application of high-temperature plasma in graphite purification, but the electric arc plasma is complex in equipment and high in cost in the graphite purification process, so that the industrial production is not facilitated.
The dielectric barrier discharge has special industrial application advantages under the atmospheric pressure. In an atmospheric pressure dielectric barrier discharge system, a micro-flow discharge mode is the most main, the most common and the most easily realized discharge mode, the discharge mode has been applied in the field of industrial ozone synthesis for more than a hundred years, but the plasma chemical reaction efficiency adopting the discharge mode is not high until now. Compared with micro-flow injection discharge, glow discharge has more efficient plasma chemical reaction performance, but large-space glow discharge is very difficult to realize under atmospheric pressure, and atmospheric pressure glow discharge can only be realized under the He gas environment at present, so that the application of a glow discharge mode in plasma chemical reaction is limited.
The use of dielectric barrier discharge, which generally generates micro-streaming discharge, is an important issue to improve the plasma energy. The invention mainly realizes that micro-flow injection carried glow discharge plasma is generated under the micro-flow injection discharge condition, so that the generated plasma active particles have higher chemical activity, and simultaneously, a large amount of graphite materials can be continuously processed due to the design of the device, thereby realizing the technical aims of easy manufacture and operation of equipment, good purification effect and low cost in the technical field of graphite purification.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a plasma contact type graphite purification device.
The technical problem is solved by the following technical scheme. The plasma contact type graphite purification device comprises: oxidation reaction system, discharge system, charge-in system, purification system.
The oxidation reaction system comprises a plasma reactor, a buffer tank, a first feeding valve, a third feeding valve and a first feeding pump;
the discharge system comprises a high-voltage power supply and a grounding device;
the feeding system comprises a graphite suspension storage tank, a second feeding valve and a second feeding pump;
the purification system comprises a first centrifugal separator, a second centrifugal separator, an impurity tank, an oxidized graphite tank, a graphite storage tank, a reducing agent dissolving tank, a fourth feed valve, a fifth feed valve, a sixth feed valve, a seventh feed valve, an eighth feed valve, a ninth feed valve, a tenth feed valve, an eleventh feed valve, a third feed pump, a fourth feed pump and a fifth feed pump.
The plasma reactor comprises an inner cylinder, an outer cylinder, an air inlet pipe, an air outlet pipe, a high-voltage electrode, a dielectric plate, a guide plate, a feeding pipe and a feeding distributor.
The high voltage power supply of the discharge system is directly connected with the high voltage electrode of the plasma reactor, the grounding device is used for grounding the inner cylinder of the plasma reactor, and the material in the inner cylinder is conductive material.
The power supply of the plasma reactor depends on a discharge system, a high-voltage electrode and a dielectric plate in the plasma reactor are arranged above the liquid level of the graphite suspension liquid in the inner cylinder, the high-voltage electrode is made of stainless steel, criss-cross grooves are machined on the surface of the high-voltage electrode, the width of each adjacent groove is 0.1-1mm, the depth of each adjacent groove is 0.1-2mm, and the dielectric plate is α -Al2O3A certain gap is arranged below the high-voltage electrode;
the distance between the plane of the inner cylinder opening and the dielectric plate is 1-7 mm. The grounding device is used for grounding the solution in the inner cylinder, so that low-temperature plasma is generated between the dielectric plate and the liquid surface.
The inner cylinder and the outer cylinder are sleeved together, the inner cylinder is a metal conductive torch, the outer cylinder is not conductive, and after the inner cylinder is grounded, materials in the inner cylinder and the inner cylinder are grounded. The diameter of the outer cylinder is larger than that of the inner cylinder, the outer cylinder is higher than the inner cylinder, the inner cylinder is filled with graphite suspension liquid, and the graphite suspension liquid can overflow from the upper end and enter the outer cylinder; the liquid level of the graphite suspension in the inner cylinder is contacted with the discharge plasma, and molecules in the new liquid level are contacted with the discharge plasma along with the flowing of the suspension into the outer cylinder;
the guide plate is designed in the inner cylinder and is cylindrical, a feeding pipe is arranged in the middle of the guide plate, and a feeding distributor is arranged at the upper part of the feeding pipe;
the buffer tank is connected with the outer barrel through a third feeding valve and is connected to a feeding pipe of the plasma reactor through a first feeding valve and a first feeding pump; the graphite suspension storage tank is connected to the feeding pipe through a second feeding valve and a second feeding pump.
The first centrifugal separator is connected with the buffer tank through an eleventh feed valve, and the second centrifugal separator is connected with the first centrifugal separator through a fifth feed valve and a fifth feed pump; the other side of the second centrifugal separator is connected to the feeding pipe through a fourth feeding valve and a fourth feeding pump.
The impurity tank is connected with the lower end of the first centrifugal separator through a seventh feed valve, the graphite oxide tank is connected with the lower end of the second centrifugal separator through an eighth feed valve, the upper end of the graphite oxide tank is connected with the reducing agent dissolving tank through a sixth feed valve and a third feed pump, the lower end of the reducing agent dissolving tank enters the graphite oxide tank through a ninth feed valve, and the lower end of the graphite oxide tank is connected with the graphite storage tank through a tenth feed valve.
The method selects a needle-plate type dielectric barrier discharge plasma reactor, the graphite plasma contact type plasma reactor is a heterogeneous cylindrical reactor, the reactor adopts a rectangular thin plate structure, the electrodes are asymmetric electrodes, when the atmospheric pressure non-equilibrium plasma reactor works, the current and voltage waveforms are adopted, the positive half period and the negative half period of discharge show asymmetric current characteristics, the positive half period of discharge shows short current pulses, and the negative half period almost does not have short current pulses, so that two different discharge modes are generated in the discharge gap of the reactor, the local electric field in the discharge gap can be strengthened, and the efficiency of the atmospheric pressure non-equilibrium plasma reactor is improved.
In the operation process of the device, the second feeding valve and the second feeding pump are firstly opened, so that the graphite suspension liquid enters the feeding pipe through the feeding system, and the newly-entering material moves upwards along the guide plate. When the inner cylinder is filled with the suspension liquid, the incoming material pushes the original material in the feeding pipe to move to the liquid level along the feeding pipe, and the material is contacted with the discharge plasma on the liquid level;
then opening an air inlet pipe of the plasma reactor, starting a high-voltage power supply of a discharge system, and generating discharge plasma between the dielectric plate and the liquid level;
when the liquid in the outer cylinder reaches a certain height and cannot exceed the liquid level of the inner cylinder, the third feeding valve is opened, so that the graphite suspension liquid treated by the discharge plasma enters the buffer tank, the graphite suspension liquid in the buffer tank has two paths, wherein one path is that the graphite suspension liquid reacts with the plasma to reach the expected index, namely, the reaction product graphite oxide, and the other path is that the graphite suspension liquid reacts with the plasma to not reach the expected index, namely, the semi-finished product, and the graphite suspension liquid is injected into the inner cylinder to continue to react with the plasma.
And (3) carrying out low-speed centrifugal separation on the reaction product graphite oxide entering the first centrifugal separator in the first centrifugal separator, injecting the centrifugal residues serving as impurities into an impurity tank, injecting the turbid liquid into the second centrifugal separator for high-speed centrifugal separation, injecting the centrifugal solids serving as graphite oxide after solid-liquid separation into the graphite oxide tank, and injecting the centrifugal liquid into the inner cylinder of the plasma reactor.
At this time, the reducing agent is injected into the graphite oxide tank to carry out reduction reaction, and the reacted material is injected into the graphite storage tank.
Compared with the prior art, the invention has the beneficial effects that:
the invention aims at the problems in graphite purification, in particular to the problems in the electric arc plasma purification technology, adopts the dielectric barrier discharge plasma technology to purify graphite, solves the problems of long period and high cost in the high-temperature plasma purification, has simple structure, easy manufacture and energy saving, does not generate waste liquid in the whole process, does not need sewage treatment and discharge, reduces the cost, protects the environment, and ensures that the high-purity graphite product prepared by the plasma method has good quality, effectively reduces the production energy consumption and reduces the production cost.
Drawings
FIG. 1 is a schematic view of a plasma contact graphite purification apparatus;
FIG. 2 is a schematic diagram of the electrode structure of the plasma reactor (1);
FIG. 3 is a schematic diagram of the electrode structure of the plasma reactor (2);
fig. 4 is a graph of plasma reactor current voltage waveforms.
The figure is as follows:
1 plasma reactor, 2 grounding device, 3 high voltage power supply, 4 buffer tank, 5 first centrifuge, 6 second centrifuge, 7 graphite suspension storage tank, 8 trash tank, 9 oxidized graphite tank, 10 graphite storage tank, 11 reducing agent dissolving tank, 12 first feed valve, 13 second feed valve, 14 third feed valve, 15 fourth feed valve, 16 fifth feed valve, 17 sixth feed valve, 18 seventh feed valve, 19 eighth feed valve, 20 ninth feed valve, 21 tenth feed valve, 22 first feed pump, 23 second feed pump, 24 third feed pump, 25 fourth feed pump, 26 eleventh feed valve, 27 fifth feed pump, 28 grounding electrode;
1-1 inner cylinder, 1-2 outer cylinders, 1-3 air inlet pipes, 1-4 air outlet pipes, 1-5 high-voltage electrodes, 1-6 dielectric plates, 1-7 guide plates, 1-8 feed pipes and 1-9 feed distributors.
Detailed Description
Embodiment mode 1:
as shown in fig. 1, the plasma contact graphite purification device comprises: oxidation reaction system, discharge system, charge-in system, purification system.
The oxidation reaction system comprises a plasma reactor 1, a buffer tank 4, a first feeding valve 12, a third feeding valve 14 and a first feeding pump 22;
the discharge system comprises a high-voltage power supply 3 and a grounding device 2;
the feeding system comprises a graphite suspension storage tank, a second feeding valve and a second feeding pump;
the purification system comprises a first centrifugal separator 5, a second centrifugal separator 6, an impurity tank 8, a graphite oxide tank 9, a graphite storage tank 10, a reducing agent dissolving tank 11, a fourth feed valve 15, a fifth feed valve 16, a sixth feed valve 17, a seventh feed valve 18, an eighth feed valve 19, a ninth feed valve 20, a tenth feed valve 21, an eleventh feed valve 26, a third feed pump 24, a fourth feed pump 25, and a fifth feed pump 27.
As shown in attached figure 1, a plasma reactor 1 comprises an inner cylinder 1-1, an outer cylinder 1-2, an air inlet pipe 1-3, an air outlet pipe 1-4, a high-voltage electrode 1-5, a dielectric plate 1-6, a guide plate 1-7, a feed pipe 1-8 and a feed distributor 1-9;
a high-voltage power supply 3 of the discharge system is directly connected with high-voltage electrodes 1-5 of a plasma reactor 1, a grounding device 2 is used for grounding an inner cylinder 1-1 of the plasma reactor 1, and materials in the inner cylinder 1-1 are conductive materials.
The electrode structure in the plasma reactor 1 adopts a structure A shown in figure 2, a high-voltage electrode 1-5 and a dielectric plate 1-6 are arranged above the liquid level of graphite suspension in an inner cylinder 1-1, the high-voltage electrode 1-5 is made of stainless steel, criss-cross grooves are processed on the surface, the width of the adjacent grooves is 0.1mm, the depth of the adjacent grooves is 0.1mm, and the dielectric plate 1-6 is α -Al2O390 percent by mass, the dielectric material is processed into the dielectric material with the size of 180mm in length, 130mm in width and 0.64mm in height, the grain size is distributed in 1-5 mu m, the vertical depth is within 0.5 mu m, and the loss factor tan delta of the dielectric material is less than or equal to 3 multiplied by 10-4The loss factor is small, and the energy loss in the discharging process is reduced; the insulation strength is more than or equal to 13kV/mm, and the dielectric layer can be prevented from being broken down under a strong electric field. The edge of the dielectric plate extends 5-10mm beyond the edge of the high-voltage electrode and is below the high-voltage electrode 1-5 at the power frequencyCan be in the range of 5-30kHz, and the voltage can be continuously adjusted in the range of 1-10 kV. The distance between the plane of the inner cylinder opening and the dielectric plate is 1mm, the schematic structural diagrams of the discharge electrode of the plasma reactor are shown in fig. 2 and fig. 3, and the current-voltage waveform diagram of the plasma reactor shown in fig. 4 is generated by using the structural arrangement of the discharge electrode of the plasma reactor;
the plasma reactor 1 is powered by means of a discharge system.
The grounding device 2 is used for grounding the solution in the inner cylinder 1-1, so that low-temperature plasma is generated between the dielectric plate 1-6 and the liquid surface.
The inner cylinder 1-1 and the outer cylinder 1-2 are sleeved together, the inner cylinder 1-1 is a metal conductive torch, the outer cylinder 1-2 is not conductive, and after the inner cylinder 1-1 is grounded, the materials in the inner cylinder 1-1 and the inner cylinder 1-1 are grounded. The diameter of the outer cylinder 1-2 is larger than that of the inner cylinder 1-1, the outer cylinder 1-2 is higher than that of the inner cylinder 1-1, the inner cylinder 1-1 is filled with graphite suspension liquid, and the graphite suspension liquid can overflow from the upper end and enter the outer cylinder 1-2; the liquid level of the graphite suspension in the inner cylinder 1-1 is contacted with the discharge plasma, and molecules in the new liquid level are contacted with the discharge plasma along with the flowing of the suspension into the outer cylinder 1-2;
the guide plate 1-7 is designed in the inner cylinder 1-1 and is cylindrical, a feed pipe 1-8 is arranged in the middle of the guide plate 1-7, and a feed distributor 1-9 is arranged at the upper part of the feed pipe 1-8;
the buffer tank 4 is connected with the outer cylinder 1-2 through a third feeding valve 14, and the buffer tank 4 is connected to the feeding pipes 1-8 of the plasma reactor 1 through a first feeding valve 12 and a first feeding pump 22; the graphite suspension tank 10 is connected to the feed pipes 1-8 via a second feed valve 13 and a second feed pump 23.
The first centrifugal separator 5 is connected with the buffer tank 4 through an eleventh feed valve 26, and the second centrifugal separator 6 is connected with the first centrifugal separator 5 through a fifth feed valve 16 and a fifth feed pump 27; the second centrifuge 6 is connected on the other side to the feed lines 1-8 via a fourth feed valve 15 and a fourth feed pump 25.
The first centrifugal separator 5 is a low-speed centrifugal separation device, and the second centrifugal separator 6 is a high-speed centrifugal separation device.
The impurity tank 8 is connected with the lower end of the first centrifugal separator 5 through a seventh feeding valve 18, the graphite oxide tank 9 is connected with the lower end of the second centrifugal separator 6 through an eighth feeding valve 19, the upper end of the graphite oxide tank 9 is connected with the reducing agent dissolving tank 11 through a sixth feeding valve 17 and a third feeding pump 24, the lower end of the reducing agent dissolving tank 11 enters the graphite oxide tank 9 through a ninth feeding valve 20, and the lower end of the graphite oxide tank 9 is connected with the graphite storage tank 10 through a tenth feeding valve 21.
The method selects a needle-plate type dielectric barrier discharge plasma reactor, the graphite plasma contact type plasma reactor is a heterogeneous cylindrical reactor, the reactor adopts a rectangular thin plate structure, the electrodes are asymmetric electrodes, the current and voltage waveforms of the atmospheric pressure non-equilibrium plasma reactor are shown in figure 4 when in work, the positive half period and the negative half period of discharge show asymmetric current characteristics, the positive half period of discharge shows short current pulses, and the negative half period almost does not have short current pulses, so that two different discharge modes are generated in the discharge gap of the reactor, the local electric field in the discharge gap can be strengthened, and the efficiency of the atmospheric pressure non-equilibrium plasma reactor is improved.
During the operation of the device, the second feeding valve 13 and the second feeding pump 23 are firstly opened, so that the graphite suspension liquid enters the feeding pipes 1-8 through the feeding system, and the newly-incoming material moves upwards along the guide plates 1-7. When the inner cylinder 1-1 is filled with the graphite suspension liquid, the incoming material pushes the original material in the feeding pipe 1-8 to move to the liquid surface along the feeding pipe 1-8, and the original material is contacted with the discharge plasma on the liquid surface;
then opening an air inlet pipe 1-3 of the plasma reactor 1, starting a high-voltage power supply 3 of a discharge system, and generating discharge plasma between the dielectric plate 1-6 and the liquid level;
when the liquid in the outer cylinder 1-2 reaches a certain height and cannot exceed the liquid level of the inner cylinder 1-1, the third feeding valve 14 is opened, so that the graphite suspension liquid treated by the discharge plasma enters the buffer tank 4, the graphite suspension liquid in the buffer tank 4 has two paths, one path is that the graphite suspension liquid reacts with the plasma to reach a material with an expected index, namely reaction product graphite oxide, and the reaction product graphite oxide is injected into the first centrifugal separator 5, and the other path is that the graphite suspension liquid does not react with the plasma to reach the expected index, namely a semi-finished product, and the semi-finished product is injected into the inner cylinder 1-1 and continuously reacts with the plasma.
The reaction product graphite oxide entering the first centrifugal separator 5 is subjected to low-speed centrifugal separation in the first centrifugal separator 5, centrifugal residues are impurities and are injected into an impurity tank 8, turbid liquid is injected into the second centrifugal separator 6 for high-speed centrifugal separation, centrifugal solids after solid-liquid separation are graphite oxide and are injected into a graphite oxide tank 9, and centrifugal liquid is injected into the inner cylinder 1-1 of the plasma reactor 1.
At this time, a reducing agent is injected into the graphite oxide tank 9 to perform a reduction reaction, and the reacted material is injected into the graphite storage tank 10.
The invention aims at the problems in graphite purification, in particular to the problems in the electric arc plasma purification technology, adopts the dielectric barrier discharge plasma technology to purify graphite, solves the problems of long period and high cost in the high-temperature plasma purification, has simple structure, easy manufacture and energy saving, does not generate waste liquid in the whole process, does not need sewage treatment and discharge, reduces the cost, protects the environment, and ensures that the high-purity graphite product prepared by the plasma method has good quality, effectively reduces the production energy consumption and reduces the production cost.
Embodiment mode 2:
according to the embodiment 1, the high-voltage electrode 1-5 and the dielectric plate 1-6 of the plasma reactor 1 are optimally designed, specifically, the high-voltage electrode 1-5 and the dielectric plate 1-6 in the discharge system are arranged above the liquid level of the graphite suspension in the inner cylinder 1-1, the high-voltage electrode 1-5 is made of stainless steel, the surface is processed with criss-cross grooves, the width of the adjacent grooves is 1mm, the depth is 2mm, and the dielectric plate 1-6 is α -Al2O399 percent by mass, the dielectric material is processed into the dielectric material with the size of 180mm in length, 130mm in width and 0.64mm in height, the grain size is distributed in 1-5 mu m, the vertical depth is within 0.5 mu m, and the loss factor tan delta of the dielectric material is less than or equal to 3 multiplied by 10-4The loss factor is small, and the energy loss in the discharging process is reduced; the insulating strength is more than or equal to 13kV/mm, and the dielectric layer can be preventedIs broken down in a strong electric field. The edge of the dielectric plate extends 5mm out of the edge of the high-voltage electrode, the power supply frequency can be in the range of 5-30kHz and the voltage can be continuously adjusted in the range of 1-10kV below the high-voltage electrode 1-5, and the distance between the plane of the cylinder opening of the inner cylinder and the dielectric plate is 7 mm.
Embodiment mode 3:
according to the embodiment 1, the specific parameters of the high voltage electrode 1-5 and the dielectric plate 1-6 of the plasma reactor 1 are designed, specifically, the high voltage electrode 1-5 and the dielectric plate 1-6 in the discharge system are above the graphite suspension liquid level of the inner cylinder 1-1, the high voltage electrode 1-5 is made of stainless steel, the surface is processed with criss-cross grooves, the width of the adjacent grooves is 0.5mm, the depth is 1mm, and the dielectric plate 1-6 is α -Al2O399 percent by mass, the dielectric material is processed into the dielectric material with the size of 180mm in length, 130mm in width and 0.64mm in height, the grain size is distributed in 1-5 mu m, the vertical depth is within 0.5 mu m, and the loss factor tan delta of the dielectric material is less than or equal to 3 multiplied by 10-4The loss factor is small, and the energy loss in the discharging process is reduced; the insulation strength is more than or equal to 13kV/mm, and the dielectric layer can be prevented from being broken down under a strong electric field. The edge of the dielectric plate extends out of the edge of the high-voltage electrode by 7mm, the power supply frequency can be within the range of 5-30kHz and the voltage can be continuously adjusted within the range of 1-10kV below the high-voltage electrode by 1-5, and the distance between the plane of the cylinder opening of the inner cylinder and the dielectric plate is 1 mm.
By using the device, graphite purification is carried out according to the following steps:
(1) preparing a graphite suspension liquid: putting graphite into a water-soluble tank, and preparing a graphite suspension liquid under stirring;
(2) preparing a purified graphite precursor: introducing the graphite suspension liquid obtained in the step (1) into a plasma reactor, and reacting for a certain time at a certain temperature in the presence of concentrated sulfuric acid to obtain a purified graphite precursor product;
(3) centrifugal separation of graphite impurities: injecting the purified graphite precursor product obtained in the step (2) into a first centrifugal separator, performing centrifugal separation at a rotating speed of less than 350r/min, and separating centrifugal residues to obtain a suspension liquid as a first centrifugal suspension liquid;
(4) solid-liquid separation of the purified graphite precursor: introducing the first centrifugal suspension obtained in the step (3) into a second centrifugal separator, performing centrifugal separation at a rotating speed higher than 8000r/min, and obtaining a centrifugal solid product after solid-liquid separation, wherein the centrifugal solid product is a purified graphite precursor product;
(5) preparing high-purity graphite: and (4) injecting the purified graphite precursor product obtained in the step (4) into a graphite tank, injecting a combined agent at a certain temperature, and reacting for a certain time to obtain the high-purity graphite.
Graphite with 79.4% of carbon content is used for preparing suspension, and under the conditions that the purity of NaOH is 96%, the combination agent is three NaOH compositions of reducing agents, all are chemically pure, ultra-pure water is used as a solvent, discharge gas is oxygen, and the flow is 0.1L/min, the specific experimental data are as follows:
the device can purify the graphite with the carbon content of 79.4 percent to the carbon content of more than 99 percent.
Claims (10)
1. A plasma contact graphite purification device is characterized in that: an oxidation reaction system, a discharge system, a feeding system and a purification system; the oxidation reaction system comprises a plasma reactor, a buffer tank, a first feeding valve, a third feeding valve and a first feeding pump; the discharge system comprises a high-voltage power supply and a grounding device; the feeding system comprises a graphite suspension storage tank, a second feeding valve and a second feeding pump; the purification system comprises a first centrifugal separator, a second centrifugal separator, an impurity tank, an oxidized graphite tank, a graphite storage tank, a reducing agent dissolving tank, a fourth feed valve, a fifth feed valve, a sixth feed valve, a seventh feed valve, an eighth feed valve, a ninth feed valve, a tenth feed valve, an eleventh feed valve, a third feed pump, a fourth feed pump and a fifth feed pump.
2. A plasma contact graphite purification apparatus as claimed in claim 1, wherein: the plasma reactor comprises an inner cylinder, an outer cylinder, an air inlet pipe, an air outlet pipe, a high-voltage electrode, a dielectric plate, a guide plate, a feeding pipe and a feeding distributor.
3. A plasma contact graphite purification apparatus as claimed in claim 1, wherein: the buffer tank is connected with the outer barrel through a third feeding valve and is connected to a feeding pipe of the plasma reactor through a first feeding valve and a first feeding pump; the graphite suspension storage tank is connected to the feeding pipe through a second feeding valve and a second feeding pump.
4. A plasma contact graphite purification apparatus as claimed in claim 1, wherein: the first centrifugal separator is a low-rotation-speed separator and is connected with the buffer tank through an eleventh feed valve, and the second centrifugal separator is a high-rotation-speed separator and is connected with the first centrifugal separator through a fifth feed valve and a fifth feed pump; the other side of the second centrifugal separator is connected to the feeding pipe through a fourth feeding valve and a fourth feeding pump.
5. A plasma contact graphite purification apparatus as claimed in claim 1, wherein: the impurity tank is connected with the lower end of the first centrifugal separator through a seventh feed valve, the graphite oxide tank is connected with the lower end of the second centrifugal separator through an eighth feed valve, the upper end of the graphite oxide tank is connected with the reducing agent dissolving tank through a sixth feed valve and a third feed pump, the lower end of the reducing agent dissolving tank enters the graphite oxide tank through a ninth feed valve, and the lower end of the graphite oxide tank is connected with the graphite storage tank through a tenth feed valve.
6. A plasma contact graphite purification apparatus as claimed in claim 2, wherein: the inner cylinder and the outer cylinder are sleeved together, the diameter of the outer cylinder is larger than that of the inner cylinder, the outer cylinder is higher than the inner cylinder, the inner cylinder is filled with graphite suspension liquid, and the graphite suspension liquid can overflow from the upper end and enter the outer cylinder.
7. A plasma contact graphite purification apparatus as claimed in claim 2, wherein: the high-voltage electrode and the dielectric plate are arranged above the liquid level of the graphite suspension liquid in the inner cylinder, and the dielectric plate is arranged below the high-voltage electrode.
8. A plasma contact graphite purification apparatus as claimed in claim 2, wherein: the high-voltage electrode is made of stainless steel, criss-cross grooves are machined on the surface, the width of each adjacent groove is 0.1-1mm, and the depth of each adjacent groove is 0.1-2 mm.
9. The plasma contact graphite purification device of claim 2, wherein the dielectric plate is α -Al2O3The mass fraction is 90-99%, the gap between the dielectric plate and the high-voltage electrode is 0-1mm, the edge of the dielectric plate extends out of the edge of the high-voltage electrode by 5-10mm, and the distance between the plane of the inner cylinder opening and the dielectric plate is 1-7 mm.
10. A plasma contact graphite purification apparatus as claimed in claim 2, wherein: the guide plate is designed in the inner cylinder and is cylindrical, a feeding pipe is arranged in the middle of the guide plate, and the upper part of the feeding pipe is provided with a feeding distributor.
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