CN113816743A

CN113816743A - High-strength graphite electrode joint preparation device and process

Info

Publication number: CN113816743A
Application number: CN202110867960.8A
Authority: CN
Inventors: 康进才; 杜爱芳; 吴沣; 路培中; 王志强; 张奇; 胡春玉; 魏帅飞; 宋洋; 苏双军; 张谦; 陈文来; 郑建华; 余全豪
Original assignee: Kaifeng Pingmei New Carbon Material Technology Co ltd
Current assignee: Kaifeng Pingmei New Carbon Material Technology Co ltd
Priority date: 2021-07-30
Filing date: 2021-07-30
Publication date: 2021-12-21

Abstract

The invention relates to a preparation process of a high-strength graphite electrode joint, which comprises the following steps: s1, preheating: preheating needle-shaped coke aggregate in a No. I pot, and simultaneously adding coal-based needle-shaped coke powder and an additive in a No. II pot for preheating and dry mixing; s2, primary kneading: feeding the needle-shaped coke aggregate preheated by the S1 into a No. III pot, adding a binder into the No. III pot, kneading and stirring to ensure that the primary paste is uniform; s3, secondary kneading: feeding the preheated coal-based needle coke powder material of S1 into a No. III pot for kneading, and adding the binder again for kneading to obtain a graphite electrode joint secondary paste material; s4, extruding and forming the secondary paste into a graphite electrode joint green body, carrying out impregnation roasting, and carrying out graphitization and high temperature treatment to obtain a final graphite product; according to the graphite electrode joint preparation device and the process, the domestic needle coke is used for producing the graphite electrode joint, the production cost is reduced, and the breaking strength of the graphite electrode joint is improved by 10-30%.

Description

High-strength graphite electrode joint preparation device and process

Technical Field

The invention belongs to the technical field of oral medical instruments, and particularly relates to a device and a process for preparing a high-strength graphite electrode joint.

Background

The graphite electrode joint is an important part for connecting two electrodes to ensure the continuous use of the electrodes in the use process of the graphite electrode. During steel making, several electrodes are connected in series to form an electrode column, the joints are not only subjected to the self weight and the thermal stress of the electrodes, but also are damaged by collapse collision and strong vibration, the graphite electrodes are often broken, and the graphite electrode joints are required to have higher mechanical strength performance. The quality of the graphite electrode joint mainly depends on three aspects of raw material performance, production equipment and process technology, wherein the raw material performance is a basic condition. At present, due to the difference in use of high-quality raw materials, the structural performance indexes of the domestic graphite electrode joint products are difficult to compare favorably with those of foreign countries, and domestic imported needle coke is limited by quality and quantity, the grade of the used imported needle coke is not high, the performance is not good, and the performance of only a few domestic needle coke is far lower than that of the imported needle coke, so that the quality of a final finished product is influenced. In the prior art, the kneading process is to uniformly mix the coke particle aggregate with a certain particle size and the powder material through preheating, dry mixing and wet mixing stages, and the condition that the large and medium particle size materials, the small particle size materials and the powder material of the coke particles are separately preheated and kneaded is not existed, so that the large and medium particles in the aggregate are easily crushed after long-time continuous stirring, and the quality of the final product is influenced; secondly, the binder asphalt is used for kneading the large and medium-sized particles to enable the binder asphalt to adhere a layer on the surfaces of the particles and the surfaces of pores, so that the defects of the particles can be compensated to a certain extent, the strength of the particles is enhanced, and the strength of the final product can be improved.

In the process of preparing the graphite electrode joint at present, preheating, dry mixing and wet mixing are needed to be carried out on materials in the kneading process, wherein, kneading systems of different models are provided with corresponding equipment in each stage, one part of the kneading systems are provided with a dry mixer in the preheating and dry mixing stages, the dry mixer has the function of heating and uniformly mixing coke particle aggregates and powder materials which are formed by certain particle sizes in the mixer, and the wet mixer is provided in the wet mixing stage for continuous mixing (also called kneading) after a liquid adhesive is added; the other part of the kneading system is provided with a heater in the preheating stage, only coke particle aggregate and powder are preheated, and the dry mixing stage and the wet mixing stage are provided with a kneading machine which is combined into a whole, so that the coke particle aggregate and the powder which are formed by certain particle sizes are uniformly mixed in the kneading machine, and the uniform mixing is continued after the liquid adhesive is added. In the process of dry mixing by using a kneader, large and medium particles in the aggregate are easily broken due to long-time continuous stirring, and the quality of the final product is affected. The existing market does not have a kneading system for preheating and dry mixing large and medium particle size materials, small particle size materials and powder materials of coke particles by using a heater and a dry mixer respectively, and the stirring knife designed in the wet mixing process can solve the defects that paste materials are easy to agglomerate and form balls in the existing continuous kneading process.

Disclosure of Invention

The invention aims to solve the problems in the background art, provides a device and a process for preparing a high-strength graphite electrode joint, overcomes the defects in the prior art, can use domestic needle coke to produce the graphite electrode joint, reduces the production cost, effectively optimizes various physical and chemical indexes of the prepared graphite electrode joint, and improves the breaking strength of the ink electrode joint by 10-30 percent.

The purpose of the invention is realized as follows:

the preparation process of the high-strength graphite electrode joint comprises the following steps:

s1, preheating: preheating needle-shaped coke aggregate in a No. I pot for 15-25min at 130-140 ℃, and simultaneously adding coal-based needle-shaped coke powder and an additive in a No. II pot for preheating and dry mixing for 30-40min at 140-150 ℃;

s2, primary kneading: feeding the needle-shaped coke aggregate preheated by the S1 into a No. III pot, adding a binder into the No. III pot, kneading and stirring for 15-20 min to make the primary paste material uniform;

s3, secondary kneading: feeding the preheated coal-based needle coke powder material of S1 into a No. III pot for kneading, and adding the binder again for kneading to obtain a graphite electrode joint secondary paste material;

and S4, extruding and forming the secondary paste obtained in the step S3 into a graphite electrode joint green body, impregnating and roasting, and graphitizing at high temperature to obtain the final graphite product.

Preferably, in S2, the binder is liquid coal pitch, the temperature for adding the binder into the No. III pot is 160-180 ℃, and the liquid coal pitch is medium-temperature modified coal pitch or modified pitch.

Preferably, in S2, the kneading temperature in the No. III pot is 150-160 ℃.

Preferably, the amount of the binder added in the first kneading in S2 is 10-30%, the amount of the binder added in the second kneading in S3 is the total residual binder, and the total amount of the binders added in S2 and S3 is 22.5-25% of the total amount of the paste.

Preferably, in S4, the number of immersion firing is 1 to 4.

Preferably, in S3, the time for the second kneading is 30-35min, and the kneading temperature is 150-160 ℃.

The utility model provides a preparation facilities for high strength graphite electrode connects preparation technology, includes I pot, II pots and III pots, the discharge gate of I pot and the discharge gate of II pots all are connected to the feed inlet of III pots through the discharging pipe respectively, be equipped with the plate electrode that is used for the heating on the inside wall of I pot, be equipped with in II pot and stir the sword, be equipped with two stirring sword of mutually supporting in III pot.

Preferably, the periphery wall of No. I pot, No. II pot and No. III pot all wraps the cladding and has the heat preservation insulating layer, the inside wall of No. II pot and No. III pot is equipped with the heat conduction oil reservoir.

Preferably, the stirring knife is provided with blades at even intervals.

Preferably, in S4, or 1-4 times of roasting, and the joint blank after the graphitization high-temperature treatment is subjected to the impregnation roasting treatment again to obtain the final finished product.

Preferably, in the 1-4 times of roasting, the primary roasting is carried out in a roasting furnace, and the curve range of the primary roasting is 400-600 h, wherein the roasting temperature in the car bottom type furnace is 750-900 ℃.

Preferably, the second firing, the third firing and the fourth firing, and the second firing to complete the graphitization treatment of the joint blank are performed in a ring furnace or a car bottom type furnace, and the graphitization is performed at a high temperature after the fourth firing is completed.

Preferably, the thermal shock resistance value R of the prepared graphite electrode meets the following requirements:

r = lambada S/(alphaE), wherein lambada is the thermal expansion coefficient of the graphite electrode, S is the tensile strength of the graphite electrode, alpha is the thermal expansion elastic modulus coefficient of the graphite electrode, E is the elastic modulus of the graphite electrode, and the thermal shock resistance value is the result of the comprehensive action of four indexes.

Preferably, the amount p of the binder coal pitch satisfies:

p = m/(m + k), wherein p is the binder dosage (%), m represents the needle coke adsorption capacity (ml/g), k is an experimental constant, the dosage of the coal pitch binder directly influences various physical and chemical properties of the product, and the dosage of the coal pitch binder is kept in a proper range, and too much or too little of the binder causes poor physical and chemical properties of the product. The amount of binder is closely related to the adsorption capacity of the solid raw material particles to the binder and the particle size composition in the product formula.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the high-strength graphite electrode joint preparation device and the process, the home-made needle coke is used for producing the graphite electrode joint, the production cost is reduced, various physical and chemical indexes of the prepared graphite electrode joint are effectively optimized, and the breaking strength of the graphite electrode joint is improved by 10-30%.

2. According to the device and the process for preparing the high-strength graphite electrode joint, the graphite electrode joint is produced by using the coal-based needle coke, so that the production cost is reduced, and the breaking strength of the graphite electrode joint is improved by 10-30%.

Drawings

FIG. 1 is a schematic view of the high-strength graphite electrode joint manufacturing apparatus and process of the present invention.

FIG. 2 is a schematic view of a stirring blade of the high-strength graphite electrode joint preparation device and process of the present invention.

FIG. 3 is a schematic view of a primary firing curve.

FIG. 4 is a schematic representation of the re-firing curve of the present invention.

FIG. 5 is a schematic diagram showing the power transmission curve performed in the graphitization high-temperature treatment after four times of calcination according to the present invention.

Fig. 6 is a schematic view of a power feeding curve performed in the graphitization high temperature treatment of firing the joint blank less than four times according to the present invention.

FIG. 7 is a comparison diagram of various physical and chemical indexes of graphite electrodes with different amounts of pitch added in one kneading process.

FIG. 8 is a graph comparing the effect of different first pitch loadings on particle porosity in graphite electrode joints in a single kneading of the present invention.

In the figure: 1. no. I pan; 2. a pot II; 3. a No. III pan; 4. an electrode plate; 5. a heat insulation layer; 6. a discharge pipe; 7. a stirring blade; 71. a blade; 8. a heat conducting oil layer.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments, and all other embodiments obtained by those skilled in the art without any creative work based on the embodiments of the present invention belong to the protection scope of the present invention.

Example 1

s1, preheating: preheating needle-shaped coke aggregate in a No. I pot 1 at 130-140 ℃ for 15-25min, and simultaneously adding coal-based needle-shaped coke powder and an additive in a No. II pot 2 to carry out dry-mixing for 30-40min at 140-150 ℃.

S2, primary kneading: feeding the needle-shaped coke aggregate preheated in the step S1 into a No. III pot 3, adding a binder into the No. III pot 3, and kneading and stirring at 150-160 ℃ for 15-20 min to make the primary paste material uniform;

the binder is liquid coal tar pitch, the temperature for adding the binder into the No. III boiler 3 is 160-180 ℃, the liquid coal tar pitch is medium-temperature modified coal tar pitch or modified pitch, and the added binder is 10-30%.

S3, secondary kneading: feeding the preheated coal-based needle coke powder material S1 into a No. 3 pot for kneading, and adding the binder again for kneading to obtain a graphite electrode joint secondary paste material;

the secondary kneading time is 30-35min, the kneading temperature is 150-160 ℃, and the added binder is all the residual binder.

And S4, extruding and forming the secondary paste obtained in the step S3 into a graphite electrode joint green body, carrying out not less than four times of dipping and roasting, carrying out graphitization high-temperature treatment to obtain a final graphite product, or carrying out not less than four times of roasting, and carrying out dipping and roasting treatment on the joint green body subjected to graphitization high-temperature treatment again to obtain a final finished product.

The total amount of the binder added in S2 and S3 is 22.5-25% of the total amount of the paste.

A process for improving the strength of graphite electrode joint includes such steps as mixing needle coke as basic material, liquid coal asphalt as adhesive and iron powder as additive, kneading, shaping, calcining and graphitizing. Wherein the raw material needle coke is oil-based needle coke or coal-based needle coke and is divided into graphite electrode joint raw material needle coke aggregate and graphite electrode joint raw material needle coke powder, and the binder liquid coal pitch is medium-temperature modified coal pitch or modified pitch; in the kneading process, the preparation method of the paste comprises the steps of respectively preheating needle-shaped coke aggregate and needle-shaped coke powder, wherein the needle-shaped coke powder and the additive are dry-mixed, firstly, mixing and kneading a part of binder liquid coal pitch and the graphite electrode joint coal-based needle-shaped coke aggregate for the first time, adding the coal-based needle-shaped coke powder, the additive and the rest binder coal pitch after uniformly mixing for the second mixing and kneading, and obtaining the graphite electrode joint paste after uniformly mixing and kneading.

Example 2

Combine fig. 1 and fig. 2, a preparation facilities for high strength graphite electrode connects preparation technology, including No. 1 pot, No. 2 pot and No. 3 pot of No. II, the discharge gate of No. 1 pot and the discharge gate of No. 2 pot all are connected to the feed inlet of No. 3 pot through discharging pipe 6 respectively, be equipped with the plate electrode 4 that is used for the heating on the inside wall of No. 1 pot, be equipped with stirring sword 7 in No. 2 pot, be equipped with two stirring sword 7 of mutually supporting in No. 3 pot.

No. I pot 1, No. II pot 2 and No. III pot 3's periphery wall all cladding has heat preservation insulating layer 5, No. II pot 2 and No. III pot 3's inside wall is equipped with heat conduction oil layer 8, be equipped with the even blade 71 in interval on the stirring sword 7.

Firstly, heating needle-shaped coke aggregate to 130-140 ℃ in a heater (No. I pot), and preheating for 15-25min (simultaneously, preheating and dry mixing coal-based needle-shaped coke powder and an additive in a mixing pot II, wherein the preheating temperature is 140-150 ℃, and the preheating time is 30-40 min); putting the preheated needle-shaped coke aggregate into a No. III kneading pot, adding liquid coal tar pitch with the temperature of 160-180 ℃, kneading and stirring for 15-20 min to ensure that the paste is uniform, wherein the adding amount of the liquid coal tar pitch is 10-30% of the total amount of the binder coal tar pitch, and the kneading temperature is 150-160 ℃; and then putting the preheated coal-based needle coke powder into a kneading pot, kneading, and then supplementing and adding the residual binder coal pitch for kneading to obtain the final paste of the graphite electrode connector, wherein the secondary kneading duration is 30-35min, the kneading temperature is 150-160 ℃, and the binder coal pitch content accounts for 22.5-25% of the total amount of the paste in the whole kneading process.

The final paste obtained by kneading is extruded and formed into a graphite electrode joint green body, and is subjected to dipping roasting for a plurality of times, and then the final graphite product is obtained after graphitization and high temperature treatment; or roasting for several times, and carrying out impregnation roasting treatment on the connector blank subjected to the graphitization high-temperature treatment again to obtain a final finished product.

Example 3

On the basis of the embodiment 1 and the embodiment 2, the manufacturing process of the high-strength graphite electrode joint comprises the steps of carrying out primary roasting in a roasting furnace, and carrying out primary roasting curve within the range of 400-600 h, wherein the roasting temperature in a vehicle bottom type furnace is 750-.

The second, third and fourth bakings, as well as the re-bake to complete the graphitized treated joint blank, are performed in a ring furnace or a car bottom furnace, wherein the baking curve for the bake in the car bottom furnace is shown in fig. 4.

The graphitization high-temperature treatment after the completion of the four times of firing is performed, and the power transmission curve is shown in fig. 5.

The graphitization high temperature treatment of the fired joint blank was performed less than four times and the power transmission curve was performed as shown in fig. 6.

With reference to fig. 7 and 8, the addition amount of the liquid coal tar pitch is 10% to 30% of the total amount of the binder coal tar pitch in the primary kneading process, various physicochemical indexes are optimized to a certain extent, and the optimization conditions of the various physicochemical indexes basically show a trend of increasing first and then decreasing with the increase of the addition amount of the liquid coal tar pitch. Firstly, the coal-based needle-shaped coke aggregate of the graphite electrode joint is kneaded for one time, which is beneficial for the liquid coal pitch of the binder to enter the pores of the granular material.

The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the invention, and any modifications, equivalents and substitutions made within the scope of the present invention should be included.

Claims

1. The preparation process of the high-strength graphite electrode joint is characterized by comprising the following steps of: the method comprises the following steps:

s1, preheating: preheating needle-shaped coke aggregate in a No. I pot (1) at 130-160 ℃ for 15-25min, and simultaneously adding coal-based needle-shaped coke powder and an additive in a No. II pot (2) to carry out dry mixing for 30-40min at 140-160 ℃;

s2, primary kneading: feeding the needle-shaped coke aggregate preheated by S1 into a No. III pot (3), adding a binder into the No. III pot (3), kneading and stirring for 15-20 min, and homogenizing the primary paste;

s3, secondary kneading: feeding the preheated coal-based needle coke powder material S1 into a No. III pot (3) for kneading, and adding the binder again for kneading to obtain a graphite electrode joint secondary paste material;

and S4, extruding and forming the secondary paste obtained in the step S3 into a graphite electrode joint green body, and carrying out dipping and roasting treatment to obtain a final graphite product.

2. The process for preparing a high-strength graphite electrode joint according to claim 1, wherein: in S2, the binder is liquid coal tar pitch, the temperature for adding the binder into the No. III pot (3) is 160-190 ℃, and the liquid coal tar pitch is medium-temperature modified coal tar pitch or modified pitch.

3. The process for preparing a high-strength graphite electrode joint according to claim 1, wherein: in S2, the kneading temperature in the No. III pot (3) is 150-180 ℃.

4. The process for preparing a high-strength graphite electrode joint according to claim 1, wherein: the mass ratio of the binder added in the first kneading in S2 is 10-30%, the binder added in the second kneading in S3 is all the rest binder, and the total amount of the binder added in S2 and S3 is 22.5-25% of the total amount of the paste.

5. The process for preparing a high-strength graphite electrode joint according to claim 1, wherein: and in S4, the times of dipping and roasting are 1-4 times, and the graphite electrode joint green body is subjected to dipping and roasting and then graphitized and high-temperature treatment to obtain the graphite product.

6. The process for preparing a high-strength graphite electrode joint according to claim 5, wherein: and (4) carrying out the impregnation roasting treatment on the graphite electrode joint green body subjected to the high-temperature treatment for no more than 2 times again to obtain a final graphite product.

7. The process for preparing a high-strength graphite electrode joint according to claim 1, wherein: in S3, the time for the second kneading is 30-35min, and the kneading temperature is 150-180 ℃.

8. A manufacturing apparatus for use in the manufacturing process of the high-strength graphite electrode tab according to any one of claims 1 to 7, characterized in that: including I pot (1), No. II pot (2) and No. III pot (3), the discharge gate of I pot (1) and the discharge gate of No. II pot (2) all are connected to the feed inlet of No. III pot (3) through discharging pipe (6) respectively, be equipped with plate electrode (4) that are used for the heating on the inside wall of I pot (1), be equipped with in No. II pot (2) and stir sword (7), be equipped with two stirring sword (7) of mutually supporting in No. III pot (3).

9. The manufacturing apparatus of the manufacturing process of the high-strength graphite electrode tab according to claim 7, wherein: no. I pot (1), No. II pot (2) and No. III pot (3) all the cladding of periphery wall has heat preservation insulating layer (5), the inside wall of No. II pot (2) and No. III pot (3) is equipped with heat conduction oil reservoir (8).

10. The manufacturing apparatus of the manufacturing process of the high-strength graphite electrode tab according to claim 7, wherein: stir and be equipped with even blade (71) in interval on sword (7), stir sword (7) including (mixing) shaft (72) and locate (mixing) shaft (72) bottom be arc structure be no less than two knee (73), blade (71) dislocation row locate on knee (73), no less than two knee (73) be discoid and arrange.