CN111302337B - Plasma contact type graphite purifying device - Google Patents
Plasma contact type graphite purifying device Download PDFInfo
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- CN111302337B CN111302337B CN202010261979.3A CN202010261979A CN111302337B CN 111302337 B CN111302337 B CN 111302337B CN 202010261979 A CN202010261979 A CN 202010261979A CN 111302337 B CN111302337 B CN 111302337B
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 137
- 239000010439 graphite Substances 0.000 title claims abstract description 135
- 229910002804 graphite Inorganic materials 0.000 title claims abstract description 135
- 239000000725 suspension Substances 0.000 claims abstract description 43
- 239000007788 liquid Substances 0.000 claims abstract description 42
- 238000000746 purification Methods 0.000 claims abstract description 29
- 239000012535 impurity Substances 0.000 claims abstract description 17
- 238000003860 storage Methods 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 8
- 238000007599 discharging Methods 0.000 claims abstract description 7
- 229910018072 Al 2 O 3 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
- 238000000034 method Methods 0.000 abstract description 19
- 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
- 230000007613 environmental effect Effects 0.000 abstract 1
- 210000002381 plasma Anatomy 0.000 description 81
- 208000028659 discharge Diseases 0.000 description 61
- 239000000463 material Substances 0.000 description 14
- 238000000926 separation method Methods 0.000 description 13
- 239000000126 substance Substances 0.000 description 11
- 230000004888 barrier function Effects 0.000 description 7
- 238000005516 engineering process Methods 0.000 description 7
- 239000000047 product Substances 0.000 description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 6
- 239000003989 dielectric material Substances 0.000 description 6
- 239000002243 precursor Substances 0.000 description 6
- 230000009286 beneficial effect Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 230000005684 electric field Effects 0.000 description 5
- 239000007795 chemical reaction product Substances 0.000 description 4
- 238000004090 dissolution Methods 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 239000007770 graphite material Substances 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 238000009413 insulation Methods 0.000 description 3
- 239000010410 layer Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 230000001105 regulatory effect Effects 0.000 description 3
- 239000011265 semifinished product Substances 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000005272 metallurgy Methods 0.000 description 2
- 238000009832 plasma treatment Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000006722 reduction reaction Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 241000282414 Homo sapiens Species 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000013543 active substance Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000010891 electric arc Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000013072 incoming material Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000000053 physical method Methods 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000012265 solid product Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 239000010918 textile wastewater Substances 0.000 description 1
- 229910021642 ultra pure water Inorganic materials 0.000 description 1
- 239000012498 ultrapure water Substances 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- 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
-
- 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Environmental & Geological Engineering (AREA)
- Inorganic Chemistry (AREA)
- Physical Or Chemical Processes And Apparatus (AREA)
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 discharging 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, a graphite oxide tank, a graphite storage tank and a reducing agent dissolving tank. The invention has simple structure, easy manufacture, energy saving, no waste liquid generation in the whole process, no sewage treatment and discharge, cost reduction, environmental protection, good quality of the high-purity graphite product prepared by the plasma method, effective reduction of production energy consumption and production cost reduction.
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 reserve are the first in the world. Graphite materials are used as industrial raw materials, and have important roles in special industries, especially in the high-tech field, such as photovoltaic solar energy, nuclear energy, automobile industry, aerospace technology and the like, but the industries use high-purity graphite with carbon content of more than 99.9 percent and even more than 99.99 percent. The purity of the general graphite product can not meet the requirements of the high-purity graphite industry, so the development and production of the high-purity graphite material become the current trend of the development of the carbon industry, and the development of the graphite material to the wider and deeper fields is one of the problems to be solved. The grade of graphite can only reach about 97% at most through a physical beneficiation method, the grade of graphite is very difficult to be further improved by adopting the physical beneficiation method, and high-carbon and high-purity graphite with the grade of more than 99% is industrially prepared mainly by adopting a high-temperature and chemical method.
The method for purifying graphite mainly comprises a chemical method and a physical method, wherein the application of chemical reagents in the chemical method generates a large amount of acid-base waste liquid and polluting chemical substances, so that the environment and human beings are greatly polluted and injured, and the equipment is greatly corroded. The high-temperature graphite purifying technology can only be applied in special industries due to high cost and other factors. Therefore, the main problems of graphite purification in the prior art are concentrated on equipment corrosion, environmental pollution caused by acid and alkali, high energy consumption and high cost, and the main reasons of the problems are brought by the method, so that other ways or methods need to be considered for solving the problems of the existing graphite purification.
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 organic matter degradation, pollutant treatment, slipping arc discharge treatment of textile wastewater and NH preparation by using gas 3 Such liquid substances, arc plasma metallurgy and the like are examples of chemical changes realized by plasmas and high-temperature atmospheres are generated, and discharge plasmas can generate active particles with high oxidability and high-temperature environments, so that the plasma environments generated by gas discharge can be utilized, active substances (organic substances, inorganic substances or surfactants) are designed to be cooperatively injected under the action of the active particles with high oxidability formed by the discharge, and O generated by the discharge can be generated 3 Active particles of OH collide with graphite molecules and impurity molecules (Si, fe, cu, al and other oxides), then graphite is oxidized, interlayer domains are increased, a graphite combination body is cleaved, impurities and graphite oxide can be separated by utilizing specific gravity difference of the graphite oxide and the impurities, and then the graphite oxide is reduced to obtain pure graphite. For this reason, a new device needs to be developed to apply the plasma technology to the technical field of graphite purification.
The plasma discharge mode is various, and high-temperature plasma is researched for graphite purification, but because the arc plasma has complex equipment and high cost in the graphite purification process, the method is not beneficial to industrial production.
The dielectric barrier discharge at atmospheric pressure has particular industrial application advantages. In an atmospheric pressure dielectric barrier discharge system, a micro-streamer discharge mode is the most dominant, common and easy to realize, and the discharge mode has been applied in the field of industrial ozone synthesis for more than one hundred years, but the plasma chemical reaction efficiency adopting the discharge mode is not high until now. Compared with micro-streamer discharge, glow discharge has higher efficient plasma chemical reaction performance, but is very difficult to realize large-space glow discharge under the atmospheric pressure, and the atmospheric pressure glow discharge can only be realized under the He environment at present, so that the application of a glow discharge mode in plasma chemical reaction is limited.
The use of dielectric barrier discharges, typically to create micro-streamer discharges, is an important issue as to how to increase their plasma energy. The invention mainly realizes that micro-current carrying glow discharge plasma is generated under the micro-current discharge condition, so that the generated plasma active particles have higher chemical activity, and simultaneously, due to the design of the device, a large amount of graphite materials can be continuously processed, thereby realizing the technical targets 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 and the shortcomings of the prior art and provides a plasma contact type graphite purifying device.
The invention solves the technical problems through the following technical scheme. The plasma contact type graphite purifying device comprises: 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 feed valve, a third feed valve and a first feed pump;
the discharging 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, a graphite oxide 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 feed pipe and a feed distributor.
The high-voltage power supply of the discharge system is directly connected with the high-voltage electrode of the plasma reactor, and the grounding device is used for grounding the inner cylinder of the plasma reactor, wherein the material in the inner cylinder is a 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 inner cylinder graphite suspension, the high-voltage electrode is made of stainless steel, crisscrossed grooves are processed on the surface, the width of each adjacent groove is 0.1-1mm, the depth is 0.1-2mm, and the dielectric plate is alpha-Al 2 O 3 A certain gap is arranged below the high-voltage electrode;
the distance between the plane of the inner cylinder opening and the dielectric plate is 1-7mm. 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 level.
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, the 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 that of the inner cylinder, and the inner cylinder is filled with graphite suspension liquid, so that the graphite suspension liquid can overflow from the upper end and enter the outer cylinder; the liquid surface of the graphite suspension in the inner cylinder is contacted with the discharge plasma, and new molecules in the liquid surface are contacted with the discharge plasma along with the flowing of the suspension into the outer cylinder;
the guide plate is designed inside the inner cylinder and is cylindrical, a feed pipe is arranged in the middle of the guide plate, and a feed distributor is arranged at the upper part of the feed pipe;
the buffer tank is connected with the outer cylinder through a third feed valve, and is connected to a feed pipe of the plasma reactor through a first feed valve and a first feed pump; the graphite suspension storage tank is connected to the feed pipe through a second feed valve and a second feed 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 needle-plate type dielectric barrier discharge plasma reactor is selected, the graphite plasma contact plasma reactor is a heterogeneous cylindrical reactor, the reactor adopts a rectangular thin flat plate structure, electrodes are asymmetric electrodes, the atmospheric pressure unbalanced plasma reactor works with current and voltage waveforms, positive and negative discharge half periods show asymmetric current characteristics, the positive discharge half periods show short current pulses, and the negative half periods almost have no short current pulses, so that two different discharge modes are generated in a discharge gap of the reactor, the local electric field in the discharge gap can be enhanced, and the efficiency of the atmospheric pressure unbalanced 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 graphite suspension liquid enters the feeding pipe through the feeding system, and newly-entered materials move upwards along the guide plate. When the inner cylinder is full of the suspension liquid, the material which is reentered pushes the original material in the feeding pipe, and the original material moves to the liquid level along the feeding pipe, and contacts with the discharge plasma at the liquid level;
then, an air inlet pipe of the plasma reactor is opened, a high-voltage power supply of a discharge system is started, and discharge plasma is generated between the dielectric plate and the liquid level;
when the liquid in the outer cylinder reaches a certain height, the liquid cannot exceed the liquid level of the inner cylinder, the third feeding valve is opened to enable the graphite suspension after discharge plasma treatment to enter the buffer tank, the graphite suspension in the buffer tank has two paths, one is that the material after the graphite suspension reacts with the plasma to reach the expected index, namely the reaction product graphite oxide, is injected into the first centrifugal separator, and the other is that the graphite suspension reacts with the plasma to not reach the expected index, namely the semi-finished product, is injected into the inner cylinder and continuously reacts 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 residue serving as impurities into an impurity tank, injecting the suspension into a second centrifugal separator for high-speed centrifugal separation, injecting the centrifugal solid subjected to solid-liquid separation into a graphite oxide tank, and injecting the centrifugal liquid into an inner barrel of the plasma reactor.
At this time, the reducing agent is injected into the graphite oxide tank for 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:
aiming at the problems existing in graphite purification, in particular to the problems existing in the arc plasma purification technology, the invention adopts the dielectric barrier discharge plasma technology to carry out graphite purification, solves the problems of long period and high cost existing in the high-temperature plasma purification, has simple structure, is easy to manufacture, saves energy sources, does not generate waste liquid in the whole process, does not need sewage treatment and discharge, reduces the cost, protects the environment, ensures that the high-purity graphite prepared by the plasma method has good product quality, effectively reduces the production energy consumption and reduces the production cost.
Drawings
FIG. 1 is a schematic diagram of a plasma contact type graphite purification device;
fig. 2 is a current-voltage waveform diagram of a plasma reactor.
The diagram is:
a plasma reactor, a 2-ground device, a 3-high-voltage power supply, a 4 buffer tank, a 5 first centrifugal separator, a 6 second centrifugal separator, a 7-graphite suspension tank, an 8-impurity tank, a 9-graphite oxide tank, a 10-graphite tank, a 11-reducing agent dissolution tank, a 12 first feed valve, a 13 second feed valve, a 14 third feed valve, a 15 fourth feed valve, a 16 fifth feed valve, a 17 sixth feed valve, a 18 seventh feed valve, a 19 eighth feed valve, a 20 ninth feed valve, a 21 tenth feed valve, a 22 first feed pump, a 23 second feed pump, a 24 third feed pump, a 25 fourth feed pump, a 26 eleventh feed valve, a 27 fifth feed pump, a 28-ground electrode;
1-1 inner cylinder, 1-2 outer cylinder, 1-3 air inlet pipe, 1-4 air outlet pipe, 1-5 high-voltage electrode, 1-6 dielectric plate, 1-7 guide plate, 1-8 feeding pipe and 1-9 feeding distributor.
Detailed Description
Embodiment 1:
as shown in fig. 1, the plasma contact type graphite purifying device comprises: an oxidation reaction system, a discharge system, a feeding system and a purification system.
The oxidation reaction system comprises a plasma reactor 1, a buffer tank 4, a first feed valve 12, a third feed valve 14 and a first feed pump 22;
the discharging 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 includes 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 dissolution 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 figure 1, the 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;
the high-voltage power supply 3 of the discharge system is directly connected with the high-voltage electrode 1-5 of the plasma reactor 1, and the grounding device 2 is used for grounding the inner cylinder 1-1 of the plasma reactor 1, and the 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 liquid in an inner cylinder 1-1, the high-voltage electrode 1-5 is made of stainless steel, crisscrossed grooves are machined on the surface, the width of each adjacent groove is 0.1mm, and the depth is 0.1mm; the dielectric plates 1-6 are alpha-Al 2 O 3 90% by mass, and is processed into a dielectric material with a loss factor tan delta less than or equal to 3 multiplied by 10, wherein the size of the dielectric material is 180mm long, 130mm wide and 0.64mm high, the grain size distribution is 1-5 mu m, the vertical depth is within 0.5 mu m -4 The loss factor is small, which is beneficial to reducing the energy loss in the discharging process; the insulation strength is more than or equal to 13 kV/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 5-10mm, the power frequency can be in the range of 5-30kHz, and the voltage can be continuously regulated in the range of 1-10kV under the high-voltage electrode 1-5. The distance between the plane of the inner cylinder opening and the dielectric plate is 1mm, the schematic structural diagram of the discharge electrode principle of the plasma reactor is shown in fig. 2 and 3, and the plasma reactor current-voltage waveform diagram shown in fig. 4 is generated by using the structural arrangement of the discharge electrode;
the power supply of the plasma reactor 1 depends on the discharge system.
The grounding device 2 is used for grounding the solution in the inner cylinder 1-1, thereby generating low-temperature plasma 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, both 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, and the inner cylinder 1-1 is filled with graphite suspension liquid which can overflow from the upper end and enter the outer cylinder 1-2; the liquid surface of the graphite suspension in the inner cylinder 1-1 is contacted with the discharge plasma, and new molecules in the liquid surface 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 feed valve 14, and the buffer tank 4 is connected to the feed pipe 1-8 of the plasma reactor 1 through a first feed valve 12 and a first feed pump 22; the graphite suspension tank 10 is connected to the feed pipes 1-8 via a second feed valve 13, a second feed pump 23.
The first centrifugal separator 5 is connected to the buffer tank 4 via an eleventh feed valve 26, and the second centrifugal separator 6 is connected to the first centrifugal separator 5 via a fifth feed valve 16, a fifth feed pump 27; the second centrifuge 6 is connected on the other side to the feed pipes 1-8 via a fourth feed valve 15, 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 feed valve 18, the graphite oxide tank 9 is connected with the lower end of the second centrifugal separator 6 through an eighth feed valve 19, the upper end of the graphite oxide tank 9 is connected with the reducing agent dissolution tank 11 through a sixth feed valve 17 and a third feed pump 24, the lower end of the reducing agent dissolution tank 11 enters the graphite oxide tank 9 through a ninth feed valve 20, and the lower end of the graphite oxide tank 9 is connected with the graphite storage tank 10 through a tenth feed valve 21.
The needle-plate type dielectric barrier discharge plasma reactor is selected, the graphite plasma contact plasma reactor is a heterogeneous cylindrical reactor, the reactor adopts a rectangular thin flat plate structure, electrodes are asymmetric electrodes, current and voltage waveforms are shown in figure 4 when the atmospheric pressure unbalanced plasma reactor works, positive and negative discharge half periods are characterized by asymmetric current characteristics, short current pulses are shown in the positive discharge half periods, short current pulses are hardly present in the negative discharge half periods, two different discharge modes are generated in a discharge gap of the reactor, the local electric field in the discharge gap can be enhanced, and the efficiency of the atmospheric pressure unbalanced plasma reactor is improved.
During operation of the device, the second feed valve 13, the second feed pump 23 are first opened to allow the graphite suspension to pass through the feed system into the feed pipe 1-8, and the incoming material moves up the baffle 1-7. When the inner cylinder 1-1 is full of graphite suspension, the re-entered material pushes the original material in the feeding pipe 1-8, and moves to the liquid level along the feeding pipe 1-8, and contacts with discharge plasma on the liquid level;
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 a dielectric plate 1-6 and the liquid level;
when the liquid in the outer cylinder 1-2 reaches a certain height, the liquid level of the inner cylinder 1-1 cannot be exceeded, the third feeding valve 14 is opened, so that the graphite suspension after discharge plasma treatment enters the buffer tank 4, the graphite suspension in the buffer tank 4 has two paths, one is the material after the graphite suspension reacts with the plasma to reach the expected index, namely the reaction product graphite oxide, and the other is the semi-finished product after the graphite suspension reacts with the plasma to reach the expected index, namely the semi-finished product, and the graphite suspension is injected into the inner cylinder 1-1 and reacts with the plasma continuously.
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, the impurities are injected into an impurity tank 8, suspension is injected into a second centrifugal separator 6 for high-speed centrifugal separation, centrifugal solids after solid-liquid separation are graphite oxide, the graphite oxide tank 9 and centrifugal liquid are injected into an 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.
Aiming at the problems existing in graphite purification, in particular to the problems existing in the arc plasma purification technology, the invention adopts the dielectric barrier discharge plasma technology to carry out graphite purification, solves the problems of long period and high cost existing in the high-temperature plasma purification, has simple structure, is easy to manufacture, saves energy sources, does not generate waste liquid in the whole process, does not need sewage treatment and discharge, reduces the cost, protects the environment, ensures that the high-purity graphite prepared by the plasma method has good product quality, effectively reduces the production energy consumption and reduces the production cost.
Embodiment 2:
according to embodiment 1, the other contents are not changed, and only the following parameter design is made. 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 a discharge system are arranged above the liquid level of graphite suspension liquid in the inner cylinder 1-1, the high-voltage electrode 1-5 is made of stainless steel, criss-cross grooves are machined on the surface, the width of each adjacent groove is 1mm, and the depth is 2mm; the dielectric plates 1-6 are alpha-Al 2 O 3 99% by mass, and is processed into a dielectric material with a loss factor tan delta less than or equal to 3 multiplied by 10, wherein the size of the dielectric material is 180mm long, 130mm wide and 0.64mm high, the grain size distribution is 1-5 mu m, the vertical depth is within 0.5 mu m -4 The loss factor is small, which is beneficial to reducing the energy loss in the discharging process; the insulation strength is more than or equal to 13 kV/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 5mm, the power frequency can be in the range of 5-30kHz, the voltage can be continuously regulated in the range of 1-10kV, and the distance between the plane of the inner cylinder opening and the dielectric plate is 7mm.
Embodiment 3:
according to the embodiment 1, other contents are unchanged, 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 a discharge system are arranged above the liquid level of the graphite suspension liquid in the inner cylinder 1-1, the high-voltage electrode 1-5 is made of stainless steel, criss-cross grooves are machined on the surface, the width of each adjacent groove is 0.5mm, and the depth is 1mm; the dielectric plates 1-6 are alpha-Al 2 O 3 Mass fraction99%, and is processed into a dielectric material with a loss factor tan delta less than or equal to 3 multiplied by 10, wherein the size of the dielectric material is 180mm long, 130mm wide and 0.64mm high, the grain size distribution is 1-5 mu m, the vertical depth is within 0.5 mu m -4 The loss factor is small, which is beneficial to reducing the energy loss in the discharging process; the insulation strength is more than or equal to 13 kV/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 frequency can be in the range of 5-30kHz, the voltage can be continuously regulated in the range of 1-10kV, and the distance between the plane of the inner cylinder opening and the dielectric plate is 1mm.
With this apparatus, graphite purification was performed as follows:
(1) Preparing a graphite suspension: putting graphite into a water-soluble tank, and preparing graphite suspension under stirring;
(2) Preparation of purified graphite precursor: introducing the graphite suspension 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 lower than 350r/min, and separating out centrifugal residues to obtain a suspension which is a first centrifugal suspension;
(4) And (3) solid-liquid separation of the purified graphite precursor: introducing the first centrifugal suspension obtained in the step (3) into a second centrifugal separator, and performing centrifugal separation at a rotating speed higher than 8000r/min, wherein a centrifugal solid product obtained after solid-liquid separation is a purified graphite precursor product;
(5) Preparing high-purity graphite: and (3) injecting the purified graphite precursor product obtained in the step (4) into a graphite tank, injecting a composition agent at a certain temperature, and reacting for a certain time to obtain the high-purity graphite.
The suspension is prepared by graphite with 79.4% carbon content, under the conditions that the purity of NaOH is 96%, the composition agent is the NaOH composition of three reducing agents, the chemical purity is high, ultra-pure water is used as a solvent, the discharge gas is oxygen, and the flow is 0.1L/min, the specific experimental data are shown in the following table:
the graphite with the carbon content of 79.4 percent can be purified to the carbon content of more than 99 percent by using the device.
Claims (10)
1. A plasma contact type graphite purifying 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 feed valve, a third feed valve and a first feed pump; the discharging 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, a graphite oxide 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 type graphite purifying apparatus according to 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 feed pipe and a feed distributor.
3. A plasma contact type graphite purifying apparatus according to claim 1, wherein: the buffer tank is connected with the outer cylinder through a third feed valve, and is connected to a feed pipe of the plasma reactor through a first feed valve and a first feed pump; the graphite suspension storage tank is connected to the feed pipe through a second feed valve and a second feed pump.
4. A plasma contact type graphite purifying apparatus according to 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, 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 type graphite purifying apparatus according to 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 type graphite purifying apparatus according to 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 that of the inner cylinder, and graphite suspension liquid is filled in the inner cylinder and can overflow from the upper end and enter the outer cylinder.
7. A plasma contact type graphite purifying apparatus according to claim 2, wherein: the high voltage electrode and the dielectric plate are above the liquid level of the inner cylinder graphite suspension, and the dielectric plate is below the high voltage electrode.
8. A plasma contact type graphite purifying apparatus according to claim 2, wherein: 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, and the depth of each adjacent groove is 0.1-2mm.
9. A plasma contact type graphite purifying apparatus according to claim 2, wherein: the dielectric plate being alpha-Al 2 O 3 The mass fraction is 90-99%, and the gap between the high-voltage electrode and the high-voltage electrode is formedThe distance between the plane of the inner cylinder opening and the dielectric plate is 1-7mm, wherein the edge of the dielectric plate extends out of the edge of the high-voltage electrode by 5-10 mm.
10. A plasma contact type graphite purifying apparatus according to claim 2, wherein: the guide plate is designed inside the inner cylinder and is cylindrical, a feeding pipe is arranged in the middle of the guide plate, and a feeding distributor is arranged on the upper part of the feeding pipe.
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