Ultrahigh-power graphite electrode and manufacturing method thereof
阅读说明：本技术 一种超高功率石墨电极及其制造方法 (Ultrahigh-power graphite electrode and manufacturing method thereof ) 是由 马塾君 于 2019-09-29 设计创作，主要内容包括：本发明公开了一种超高功率石墨电极及其制造方法,制备所述超高功率石墨电极的原料包括石墨烯、针状焦、粘结剂、焙烧碎和石墨碎,原料经过煅烧及配料、混捏、压型、一次焙烧、浸渍、二次焙烧、石墨化、机械加工至成品。本发明的超高功率石墨电极生产时加入了石墨烯粉体改性,石墨烯粉体分散在石墨电极生坯中,进行石墨化工序时,石墨烯粉体既可以作为晶核使周边的碳原子在其上继续进行晶体生长,形成尺寸更大的石墨层状晶体,或生成多晶,又可以诱导周边碳原子从非晶质向晶质进行转化,生成新的石墨层状晶体,从而大幅度提高产品的石墨化程度,降低产品的电阻率,同时提高了产品的抗折强度。(The invention discloses an ultrahigh power graphite electrode and a manufacturing method thereof, wherein raw materials for preparing the ultrahigh power graphite electrode comprise graphene, needle coke, a binder, baking scraps and graphite scraps, and the raw materials are calcined, mixed, kneaded, pressed, primarily baked, impregnated, secondarily baked, graphitized and mechanically processed to obtain a finished product. The ultrahigh-power graphite electrode is modified by adding the graphene powder during production, the graphene powder is dispersed in a graphite electrode green body, and when a graphitization process is carried out, the graphene powder can be used as a crystal nucleus to enable peripheral carbon atoms to continue to carry out crystal growth on the graphene powder to form graphite lamellar crystals with larger sizes or generate polycrystal, and can also induce the peripheral carbon atoms to convert from amorphous to crystalline to generate new graphite lamellar crystals, so that the graphitization degree of the product is greatly improved, the resistivity of the product is reduced, and the breaking strength of the product is improved.)
1. The ultrahigh-power graphite electrode is characterized in that the preparation raw materials comprise the following components in percentage by weight: 0.3-0.7% of graphene, 65-73% of needle coke, 21-28% of binder, 2-5% of roasted fragments and 3-7.5% of graphite fragments.
2. The ultra-high power graphite electrode of claim 1, wherein the needle coke has a particle size composition of: 12-18% of 16-22mm, 10-15% of 6-16mm, 10-14% of 2-6mm, 22-33% of 0.075-0.5mm and 27-42% of less than 0.075 mm.
3. The ultra-high power graphite electrode according to claim 1, wherein the particle size of the calcined crushed particles is 1-2 mm; the particle size of the graphite fragments is 1-2 mm; the particle size of the graphene is less than 1 mm.
4. The ultra-high power graphite electrode as claimed in claim 1, wherein the binder is medium temperature pitch, the coking value of the medium temperature pitch is greater than or equal to 56%, the softening point is 94-99 ℃, the melting temperature is 108-.
5. The method for manufacturing an ultra-high power graphite electrode as claimed in any one of claims 1 to 4, comprising the steps of:
(1) raw material treatment: calcining, crushing, grinding and screening the raw material needle coke to obtain granular materials and powder materials of the needle coke of each grade; weighing the graphene, the crushed graphite, the roasted crushed graphite, the binder and the granular materials and powder materials of the needle coke of each grade;
(2) kneading: mixing the graphene with the granular materials and the powder materials of the needle coke of each grade, adding crushed graphite and roasted crushed graphite, and mixing to form a mixed material; uniformly stirring the mixed material and the binder in a kneading pot, and kneading into a plastic paste;
(3) profiling: feeding the plastic paste into a vertical tamping horizontal press, loading and prepressing the plastic paste for 2-5min, extruding the paste from an extrusion nozzle at the speed of 25-26 mm/sec under the pressure of 32-35MN, and shearing an electrode when the required length is reached to obtain a green body with the preset size;
(4) roasting: roasting the green body under the protection of the filler to obtain a roasted body;
(5) impregnation and secondary roasting: after the surface of the roasting blank is cleaned, preheating to the temperature of 260-380 ℃, putting the roasting blank into an impregnation device, vacuumizing to 8-9KPa, then injecting impregnation asphalt with the temperature of 180-200 ℃, pressurizing the system to 1.2-1.5MPa, returning the asphalt and cooling the system; carrying out secondary roasting on the impregnated blank in the roasting furnace (4) so as to remove volatile components from the impregnated asphalt and coke the impregnated asphalt;
(6) graphitization: placing the roasting blank after secondary roasting in an internal heat series furnace, and heating the soaked roasting blank to 2300-plus-3000 ℃ according to a preset power curve in the presence of a protective medium to obtain a graphitized blank;
(7) and (3) machining: and (3) processing the graphitized blank into the required electrode body and/or electrode joint by numerical control processing.
6. The method according to claim 5, wherein the raw material is treated by calcining with the combustion heat of the volatile components in the raw material and the added fuel, and naturally raising the temperature, the maximum temperature of the calcining is controlled to 1250-; indirectly cooling the calcined product to below 100 ℃ by water jacket cooling circulating water to discharge coke; the density of the needle coke is controlled to be 2.12g/cm3The above.
7. The method of claim 5, wherein the calcined needle coke is sieved to a particle size of 0.5 to 22mm and a powder size of 0.075 to 0.5mm and less than 0.075 mm.
8. The method according to claim 5, wherein in the step (2), the temperature in the kneading pot is controlled to be 140 ℃ and 160 ℃ when the mixture and the binder are kneaded, and the kneading time is 35-45 min.
9. The method of claim 5, wherein in step (3), a green article of 625mm x 2550mm is obtained, and the green density of the acceptable article is not less than 1.70g/cm3。
10. The manufacturing method according to claim 5, wherein in the step (4), the filler is metallurgical coke and has the following composition: ash content is less than or equal to 15%, fixed carbon is more than or equal to 83%, and water content is less than or equal to 0.5%.
Technical Field
The invention relates to the technical field of electrode manufacturing, in particular to an ultrahigh-power graphite electrode and a method for manufacturing the ultrahigh-power graphite electrode.
Background
The graphite electrode is a conductor for heating and melting furnace burden by releasing electric energy in an electric arc mode in an electric arc furnace, and can be divided into a common power graphite electrode, a high-power graphite electrode and an ultrahigh-power graphite electrode according to the quality index.
With the development of large-scale and ultrahigh power electric furnace steelmaking, the diameter of the graphite electrode is also increased in size. Patent application 2017103305274 discloses a large-size high-power graphite electrode, which uses petroleum coke and needle coke as main raw materials, and uses medium-temperature modified asphalt with high coking value as a binder, so as to reduce the procedures of impregnation and secondary roasting, and obtain the large-size high-power graphite electrode.
Graphene is one of the materials with the highest known strength at present, has good toughness, has very good heat conduction performance, has the heat conduction coefficient of 5300W/mK of pure defect-free single-layer graphene, is a carbon material with the highest heat conduction coefficient at present, and is higher than that of a single-wall carbon nanotube and a multi-wall carbon nanotube; and the thermal conductivity coefficient of the graphene used as a carrier can also reach 600W/mK. The modification of the graphite electrode or the graphite electrode joint by utilizing the graphene is one of means for improving the performance of the graphite electrode, and the patent application 2018110227058 discloses a graphite electrode joint containing the graphene, wherein a powdery graphene raw material is added in the graphite electrode joint, so that the bending resistance of the electrode joint can be improved, and the oxidation resistance of the electrode joint in a high-temperature state is enhanced. However, the amount of graphene added for modification is very large, which increases the production cost.
Disclosure of Invention
In view of the defects in the prior art, one of the purposes of the present invention is to provide a graphene-modified ultrahigh-power graphite electrode, which can effectively reduce the resistivity and the thermal expansion coefficient of the ultrahigh-power graphite electrode by adding graphene into the raw material of the graphite electrode.
Still another object of the present invention is to provide a method for preparing the ultra-high power graphite electrode.
In order to achieve the purpose, the invention adopts the following scheme:
an ultrahigh-power graphite electrode is prepared from the following raw materials in percentage by weight: 0.3-0.7% of graphene, 65-73% of needle coke, 21-28% of binder, 2-5% of roasted fragments and 3-7.5% of graphite fragments.
Preferably, the particle size composition of the needle coke is: 12-18% of 16-22mm, 10-15% of 6-16mm, 10-14% of 2-6mm, 22-33% of 0.075-0.5mm and 27-42% of less than 0.075 mm.
Preferably, the particle size of the roasted flakes is 1-2 mm.
Preferably, the particle size of the graphite particles is 1-2 mm.
Preferably, the graphene has a particle size of less than 1 mm.
Preferably, the binder is medium temperature asphalt. The coking value of the adopted medium-temperature pitch is more than or equal to 56 percent, the softening point is 94-99 ℃, the melting temperature is 108-114 ℃, the content of toluene insoluble substances is 28-32 percent, and the content of quinoline insoluble substances is 8-12 percent.
The manufacturing method of the ultrahigh-power graphite electrode comprises the following steps:
(1) raw material treatment: calcining, crushing, grinding and screening the raw material needle coke to obtain granular materials and powder materials of the needle coke of each grade; weighing the graphene, the crushed graphite, the roasted crushed graphite, the binder and the granular materials and powder materials of the needle coke of each grade;
(2) kneading: mixing the graphene with the granular materials and the powder materials of the needle coke of each grade, adding crushed graphite and roasted crushed graphite, and mixing to form a mixed material; uniformly stirring the mixed material and the binder in a kneading pot, and kneading into a plastic paste;
(3) profiling: feeding the plastic paste into a vertical tamping horizontal press, loading and prepressing the plastic paste for 2-5min, extruding the paste from an extrusion nozzle at the speed of 25-26 mm/sec under the pressure of 32-35MN, and shearing an electrode when the required length is reached to obtain a green body with the preset size;
(4) roasting: roasting the green body under the protection of the filler to obtain a roasted body;
(5) impregnation and secondary roasting: after the surface of the roasting blank is cleaned, preheating to the temperature of 260-380 ℃, putting the roasting blank into an impregnation device, vacuumizing to 8-9KPa, then injecting impregnation asphalt with the temperature of 180-200 ℃, pressurizing the system to 1.2-1.5MPa, returning the asphalt and cooling the system; carrying out secondary roasting on the impregnated blank in the roasting furnace (4) so as to remove volatile components from the impregnated asphalt and coke the impregnated asphalt;
(6) graphitization: placing the roasting blank after secondary roasting in an internal heat series furnace, and heating the soaked roasting blank to 2300-plus-3000 ℃ according to a preset power curve in the presence of a protective medium to obtain a graphitized blank;
(7) and (3) machining: and (3) processing the graphitized blank into the required electrode body and/or electrode joint by numerical control processing.
Preferably, the filler in the step (4) is metallurgical coke, and the metallurgical coke comprises the following components: ash content is less than or equal to 15%, fixed carbon is more than or equal to 83%, and water content is less than or equal to 0.5%.
Preferably, the needle coke is calcined by using the combustion heat of the volatile components in the raw material and adding part of fuel, and the temperature is naturally raised, the highest temperature of the calcination is controlled to 1250-.
Preferably, after calcination, the coke is discharged by indirectly cooling the calcined coke to below 100 ℃ through water jacket cooling circulating water.
Preferably, the density of the needle coke is controlled to 2.12g/cm3The above.
Preferably, the raw needle coke is oil-based needle coke.
Preferably, the calcined needle coke is sieved into granules with the particle size of 0.5-22mm and powder with the particle size of 0.075-0.5mm and the particle size of less than 0.075 mm.
Preferably, in the step (2), when the mixed material and the binder are kneaded, the kneading temperature in the kneading pot is controlled to be 140-.
Furthermore, the particle size of the graphene powder is less than 1mm, and when the graphene powder is mixed with needle coke, the graphene powder is firstly mixed with needle coke powder with the particle size of 0.075-0.5mm, and then needle coke particles and needle coke powder with other particle sizes are added.
Preferably, in the step (3), a 625mm x 2550mm green body is obtained, and the density of the qualified product is not less than 1.70g/cm3。
The graphitized blank is machined into the required size, shape and precision by cutting, and the electrode body and the joint which meet the use requirements are manufactured. The body processing comprises boring and rough and flat end faces, turning outer circles and finish and thread milling. The conical joint machining comprises the following steps: cutting, flattening the end face, turning the conical surface, milling threads, drilling holes, installing bolts and grooving.
The invention has the beneficial effects that:
the graphene powder is added for modification during production of the graphite electrode, the graphene powder is dispersed in a graphite electrode green body, and during a graphitization process, the graphene powder can be used as a crystal nucleus to enable peripheral carbon atoms to continue to perform crystal growth on the graphene powder to form graphite layered crystals with larger sizes or generate polycrystal, and can also induce the peripheral carbon atoms to convert from amorphous to crystalline to generate new graphite layered crystals, so that the graphitization degree of the product is greatly improved, and the resistivity of the product is reduced. The increase of the graphitization degree can effectively reduce the coefficient of thermal expansion value of the product and simultaneously improve the rupture strength. The power consumption and the electrode consumption in the electric furnace steel making process can be obviously reduced, and the electric furnace steel making production cost is effectively reduced.
Detailed Description
Hereinafter, embodiments of the present invention will be described in detail. The following examples are only for illustrating the technical solutions of the present invention more clearly, and therefore are only examples, and the protection scope of the present invention is not limited thereby.
It is to be noted that, unless otherwise specified, technical or scientific terms used herein shall have the ordinary meaning as understood by those skilled in the art to which the invention pertains.
The preparation method of the ultrahigh-power graphite electrode comprises the following steps:
raw material treatment: calcining the raw material needle coke at high temperature, namely calcining by utilizing the combustion heat of volatile components in the raw material and adding part of fuel, and naturally heating, wherein the highest temperature is 1250-; indirectly cooling to below 100 deg.C by water jacket cooling circulating water after calcination, discharging water and volatile components, and controlling the true density of needle coke to be not less than 2.12g/cm3. And (3) carrying out medium crushing, grinding and screening treatment on the calcined needle coke to obtain a particle size material of 0.5-22mm and powder materials with particle sizes of 0.5-0.075mm and below 0.075 mm.
Calculating and weighing granular materials, powder materials and binders with various granularities, wherein the preparation raw materials comprise the following components in percentage by weight: 0.3-0.7% of graphene, 65-73% of needle coke, 21-28% of binder, 2-5% of roasted fragments and 3-7.5% of graphite fragments; wherein the particle size composition of the needle coke is as follows: 12-18% of 16-22mm, 10-15% of 6-16mm, 10-14% of 2-6mm, 22-33% of 0.075-0.5mm and 27-42% of less than 0.075 mm.
Kneading: mixing the graphene with the granular materials and the powder materials of the needle coke of each grade, adding crushed graphite and roasted crushed graphite, and mixing to form a mixed material; and (3) uniformly stirring the mixed material and the binder in a kneading pot, and kneading into the plastic paste. During mixing, the graphene powder is firstly mixed with needle coke with the granularity of 0.5-0.075mm, and then is mixed with needle coke particles and needle coke powder with other particle sizes. When kneading, the temperature in the kneading pot is controlled at 140-160 ℃, and the kneading time is 35-45 min. The binder is medium temperature asphalt, the coking value of the medium temperature asphalt is not less than 56 percent, the softening point is 94-99 ℃, the melting temperature is 108-114 ℃, the content of toluene insoluble substances is 28-32 percent, and the content of quinoline insoluble substances is 8-12 percent.
Profiling: and (3) feeding the plastic paste into a vertical tamping horizontal press, and loading, prepressing and extruding the plastic paste to obtain a green body with the required size.
Roasting: and roasting the green body under the protection of the filler to obtain a roasted body. And roasting the green body to carbonize the coal pitch in the green body, wherein a specific temperature rise curve during roasting is shown in table 1, the temperature is preserved at the highest temperature of 1100 ℃ for 24-25h, then the temperature is naturally reduced, and the roasted body is obtained after cooling for 70-78 h. The filling material is metallurgical coke and comprises the following components: ash content is less than or equal to 15%, fixed carbon is more than or equal to 83%, and water content is less than or equal to 0.5%.
TABLE 1 roasting temperature rise Curve
Phases
Temperature zone (. degree. C.)
Rate of temperature rise (. degree. C./h)
Duration (h)
1
100-450
4-6
70
2
450-650
1-1.2
181
3
650-820
4-5
38
4
820-1100
10
28
Impregnation and secondary roasting: after the surface of the roasting blank is cleaned, preheating to the temperature of 260-380 ℃, putting the roasting blank into an impregnation device, vacuumizing to 8-9KPa, then injecting impregnation asphalt with the temperature of 180-200 ℃, pressurizing the system to 1.2-1.5MPa, returning the asphalt and cooling the system; and (3) carrying out secondary roasting on the impregnated blank in the roasting furnace so as to remove volatile components from the impregnated asphalt and coke the impregnated asphalt.
Graphitization: and (3) placing the roasting blank after secondary roasting in an internal heat series furnace, heating the soaked roasting blank to 2300-3000 ℃ according to a preset power curve in the presence of a protective medium to obtain a graphitized blank, wherein the power transmission curve of the graphitizing treatment is shown in Table 2.
TABLE 2 Power delivery curves
Phases
Time of power transmission (h)
Power (KW)
Cumulative power transmission (KWH)
1
13
3250-6500
63375
2
17
6500-9400
198992
3
3
9400-11800
230792
4
32
11800-16000
675592
And (3) machining: and (3) processing the graphitized blank into the required electrode body and/or electrode joint by numerical control processing.
The graphite electrode meeting the requirements is prepared according to the preparation method.
- 上一篇：一种医用注射器针头装配设备
- 下一篇：多相粉体的新型二次造粒工艺