阅读说明：本技术 提高石墨电极初始焙烧坯密度的工艺制备方法 (Process preparation method for improving density of initial roasting blank of graphite electrode ) 是由 刁松 涂菁 于 2021-10-14 设计创作，主要内容包括：本发明公开了一种提高石墨电极初始焙烧坯密度的工艺制备方法,包括以下步骤：选取原料,所述原料按重量份数计包括焦砂5-80份、焦粉15-50份、石墨0.05-20份、铁红0.1-5份、酚醛树脂0.2-20份。通过更改骨料颗粒级配,降低临界粒度,且通过临界粒度和黏结剂的选择,提高了成型坯体密,实现通过提高产品初始焙烧坯的体密,生成同等级产品可减少再次浸渍与再次焙烧的次数,以此来降低了生产成本,且提高产品的生产效率和质量,提高了产品的市场竞争力,同时通过提高物料投入产出比,降低生产成本和产品生产周期,提高了产品的生产效率；通过将采用的黏结剂由煤沥清替换为酚醛树脂,可大幅减少了过去生产工艺中的有害气体、粉尘等。(The invention discloses a process preparation method for improving density of an initial roasting blank of a graphite electrode, which comprises the following steps: selecting raw materials, wherein the raw materials comprise, by weight, 5-80 parts of tar sand, 15-50 parts of coke powder, 0.05-20 parts of graphite, 0.1-5 parts of iron oxide red and 0.2-20 parts of phenolic resin. The grading of aggregate particles is changed, the critical particle size is reduced, and the critical particle size and the selection of the adhesive are adopted, so that the density of a formed blank body is improved, the density of the initial baked blank of the product is improved, the times of secondary impregnation and secondary baking can be reduced for the same-grade product generated, the production cost is reduced, the production efficiency and the quality of the product are improved, the market competitiveness of the product is improved, and meanwhile, the production cost and the production period of the product are reduced by improving the input-output ratio of materials, and the production efficiency of the product is improved; by replacing the adopted adhesive with the phenolic resin from coal tar pitch, harmful gas, dust and the like in the past production process can be greatly reduced.)

1. A process preparation method for improving density of an initial roasting blank of a graphite electrode is characterized by comprising the following steps: the method comprises the following steps:

s1, selecting raw materials, wherein the raw materials comprise, by weight, 5-80 parts of tar sand, 15-50 parts of coke powder, 0.05-20 parts of graphite, 0.1-5 parts of iron oxide red and 0.2-20 parts of phenolic resin;

s2, uniformly mixing the raw materials in the step S1 by using a high-speed mixing mill to obtain a mixed and ground material;

s3, pouring the mixed and ground material obtained in the step S2 into a press, carrying out green body forming, and then obtaining a formed body;

s4, sintering the molded blank in the step S3 for 72-480 hours in the environment of 700-2600 ℃, and obtaining the initial sintered blank of the graphite electrode.

2. The method for preparing the process for improving the density of the initial roasting blank of the graphite electrode according to claim 1, which is characterized by comprising the following steps of: the grain size of the coke sand is 0.1-5mm, and the grain size of the coke powder is 0.05-0.088 mm.

3. The method for preparing the process for improving the density of the initial roasting blank of the graphite electrode according to claim 1, which is characterized by comprising the following steps of: the raw materials also comprise 1-3 parts of additional additives by weight.

4. The method for preparing the graphite electrode initial roasting blank with the improved density according to the claim 3, is characterized in that: the step S2 includes: and mixing and grinding the coke sand, the coke powder, the graphite, the iron oxide red and the phenolic resin uniformly, and then adding the additive.

5. The method for preparing the process for improving the density of the initial roasting blank of the graphite electrode according to claim 1, which is characterized by comprising the following steps of: and the material mixing time in the step S2 is more than 30 minutes.

6. The method for preparing the process for improving the density of the initial roasting blank of the graphite electrode according to claim 1, which is characterized by comprising the following steps of: the instant temperature of the mixed and ground material in the step S3 is 10-80 ℃.

7. The method for preparing the process for improving the density of the initial roasting blank of the graphite electrode according to claim 1, which is characterized by comprising the following steps of: the press in the step S3 is a cold isostatic press of 6000 tons or more or a 3000 ton vacuum hydraulic press.

Technical Field

The invention relates to the technical field of preparation of graphite electrodes, in particular to a process preparation method for improving the density of an initial roasting blank of a graphite electrode.

Background

In recent years, the global ecological environment is deteriorated, and the sustainable development of the human society is seriously threatened. The reduction of energy consumption, the reduction of pollutant emission, the promotion of technical transformation and industrial upgrading become the consensus of the international society. The production of the graphite electrode is in the central part of the consensus, the graphite electrode is widely applied to industries such as metallurgy, chemical industry, mineral products and the like, statistics is carried out in 2020, and the yield of the graphite electrode in China in 2020 is 102 ten thousand tons, which is increased by 13.5% on a same scale. The traditional graphite electrode production is mature, and the high-temperature resistant graphite conductive material is prepared by using petroleum coke and pitch coke as aggregates and coal tar pitch as an adhesive through raw material calcination, crushing and grinding, blending, kneading, molding, roasting, impregnation, graphitization and machining.

In the traditional graphite electrode production process, although the porosity of a pressed green electrode is low, after roasting, because a binder is decomposed into gas to escape in the roasting process, and the other part of the gas is coked into asphalt coke, the porosity of a roasted semi-finished electrode is greatly increased, namely the bulk density is greatly reduced, the volume of the generated asphalt coke is far smaller than the volume originally occupied by coal tar pitch, although the binder is slightly shrunk in the roasting process, a plurality of irregular tiny pores with different sizes are still formed in the electrode, the total porosity of the graphitized electrode generally reaches 25% -32%, because the existence of the pores has negative influence on the physicochemical properties of inevitable carbon products, the porosity of graphitized products is increased, the bulk density is reduced, the resistivity is increased, the mechanical strength is reduced, the oxidation speed at a certain temperature is accelerated, and gas and liquid are easy to permeate, the corrosion resistance is also deteriorated.

In order to reduce porosity and improve bulk density in the traditional graphite electrode production process, besides trying to increase the bulk density of materials, another main method (process) is to carry out multiple times of impregnation and roasting processes (high-end electrodes are generally three-impregnation four-roasting processes), and the production has the problem of long production period (one production period is as long as 150-160 days); in the traditional graphite electrode production process, asphalt heating and high-temperature material mixing processes are adopted, so that combustible and harmful gases are inevitably generated to escape; the high-temperature mixing also increases the dust emission, and the harm of harmful gas and dust to human bodies cannot be thoroughly eliminated; pollution to the environment; the material input-output ratio is also reduced, the labor intensity of workers is high, the energy consumption is high, and the production efficiency is low.

Disclosure of Invention

The invention aims to provide a process preparation method for improving the density of an initial roasting blank of a graphite electrode, which reduces the porosity of the initial roasting blank to be below 20% by redefining the process, can reduce the times of secondary impregnation and roasting on the premise of using raw materials with the same quality, greatly improves the density of a graphite electrode forming blank, reduces the production cost of the product and improves the production efficiency of the product; meanwhile, the resistivity can be reduced, the oxidation resistance is improved, and the service life of the product is prolonged, so that the problems in the background technology are solved.

In order to achieve the purpose, the invention provides the following technical scheme: a process preparation method for improving the density of an initial roasting blank of a graphite electrode comprises the following steps:

s1, selecting raw materials, wherein the raw materials comprise, by weight, 5-80 parts of tar sand, 15-50 parts of coke powder, 0.05-10 parts of graphite, 0.1-5 parts of iron oxide red and 0.2-20 parts of phenolic resin;

s2, uniformly mixing the raw materials in the step S1 by using a high-speed mixing mill to obtain a mixed and ground material;

s3, pouring the mixed and ground material obtained in the step S2 into a press, carrying out green body forming, and then obtaining a formed body;

s4, sintering the molded blank in the step S3 for 72-480 hours in the environment of 700-2600 ℃, and obtaining the initial sintered blank of the graphite electrode.

Optionally, the grain size of the coke sand is 0.1-5mm, and the grain size of the coke powder is 0.05-0.088 mm.

Optionally, the raw materials further comprise 1-3 parts of additional additives in parts by weight.

Optionally, the step S2 includes: and mixing and grinding the coke sand, the coke powder, the graphite, the iron oxide red and the phenolic resin uniformly, and then adding the additive.

Optionally, the mixing time in the step S2 is greater than 30 minutes.

Optionally, the instant temperature of the mixed milling material in the step S3 is 10 to 80 ℃.

Optionally, the press in step S3 is a 6000 ton or more cold isostatic press or a 3000 ton vacuum hydraulic press.

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

1. according to the invention, the grading of aggregate particles is changed, the critical particle size is reduced, and the critical particle size and the binder are selected, so that the density of a formed blank body is improved, the density of the initial baked blank of the product is improved, the times of secondary impregnation and secondary baking can be reduced for the same-grade product, the production cost is reduced, the production efficiency and quality of the product are improved, the market competitiveness of the product is improved, and meanwhile, the production cost and the production period of the product are reduced and the production efficiency of the product is improved by improving the input-output ratio of materials.

2. According to the invention, the adopted adhesive is replaced by phenolic resin from coal tar pitch, so that harmful gas, dust and the like in the past production process can be greatly reduced, the harm of the dust to human bodies and the environment can be reduced, the production environment of staff is improved, the problem that the coal tar pitch is often accompanied by the escape of combustible gas in the heating process is eliminated, and the potential safety hazard of flammability and explosiveness is eliminated; compared with coal pitch, the phenolic resin has high carbon content and good carbonization effect, and leaves small pores after carbonization, so that the density of a formed green body can be improved.

Drawings

FIG. 1 is a schematic flow chart of the process for increasing the density of the initial sintered compact of the graphite electrode according to the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, in this embodiment, the method for increasing the density of the initial baked blank of the graphite electrode may include the following steps:

step S1: selecting raw materials, wherein the raw materials comprise, by weight, 5-80 parts of tar sand, 15-50 parts of coke powder, 0.05-20 parts of graphite, 0.1-5 parts of iron oxide red and 0.2-20 parts of phenolic resin.

Specifically, the raw materials comprise aggregates and a binder, wherein the aggregates comprise coke sand, coke powder, graphite and iron oxide red; the binder comprises a phenolic resin.

Optionally, in this embodiment, the particle size of the coke sand is 0.1-5mm, and the particle size of the coke powder is 0.05-0.088 mm.

Optionally, in this embodiment, the raw material further comprises 1-3 parts of an external additive.

Step S2: and (4) uniformly mixing the raw materials in the step S1 by using a high-speed mixing mill to obtain a mixed mill material.

Specifically, crushing and calcining the aggregate, and then uniformly mixing and grinding the aggregate and the adhesive to obtain pug; and then uniformly mixing and grinding the pug and the additive to obtain a mixed and ground material. The coke sand, coke powder, graphite, iron oxide red and phenolic resin are mixed and ground evenly, and then the additive is added. Wherein the mixing time is more than 30 minutes.

Optionally, in this embodiment, the pug and the additive are mixed and milled uniformly to obtain a mixed and milled material with an instant temperature of 10-80 ℃.

Step S3: and (5) pouring the mixed grinding material in the step S2 into a press, and carrying out green body forming to obtain a formed blank.

Specifically, in the present embodiment, the press is a 6000 ton or more cold isostatic press or a 3000 ton vacuum hydraulic press.

Step S4: and (4) firing the molded blank in the step S3 at the temperature of 700-2600 ℃ for 72-480 hours to obtain an initial graphite electrode fired blank.

Specifically, the molded body is fired to obtain an initial fired body of the graphite electrode.

Step S5: and (5) circularly immersing and roasting the initial roasting blank of the graphite electrode in the step (S4) for multiple times, graphitizing, and finally machining to obtain a finished product.

Specifically, in this embodiment, the medium is immersed for 40 minutes to 12 hours at a time.

Specifically, the specific size of the finished product can be set according to the customer requirements, for example, in the embodiment, the size of the graphite electrode initial baking blank is 600mm 2100 mm.

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

1. according to the invention, the grading of aggregate particles is changed, the critical particle size is reduced, and the critical particle size and the binder are selected, so that the density of a formed blank body is improved, the density of the initial baked blank of the product is improved, the times of secondary impregnation and secondary baking can be reduced for the same-grade product, the production cost is reduced, the production efficiency and quality of the product are improved, the market competitiveness of the product is improved, and meanwhile, the production cost and the production period of the product are reduced and the production efficiency of the product is improved by improving the input-output ratio of materials.

2. According to the invention, the adopted adhesive is replaced by phenolic resin from coal tar pitch, so that harmful gas, dust and the like in the past production process can be greatly reduced, the harm of the dust to human bodies and the environment can be reduced, the production environment of staff is improved, the problem that the coal tar pitch is often accompanied by the escape of combustible gas in the heating process is eliminated, and the potential safety hazard of flammability and explosiveness is eliminated; compared with coal pitch, the phenolic resin has high carbon content and good carbonization effect, and leaves small pores after carbonization, so that the density of a formed green body can be improved.

The technical solutions of the present invention are further described in detail with reference to the following specific examples, which should be understood as merely illustrative and not limitative.

Example one

S1, selecting aggregates, namely selecting 5-80 parts of asphalt needle-shaped calcined coke sand with the thickness of 0.1-5mm, 15-50 parts of asphalt needle-shaped calcined coke powder with the thickness of 0.05-0.088mm, 0.05-20 parts of graphite and 0.1-5 parts of iron oxide red; 0.2-20 parts of phenolic resin and 1-3 parts of additive are additionally selected.

And S2, uniformly mixing the raw materials in the step S1 to obtain the mixed and ground material with the instant temperature of 10-80 ℃.

And S3, pouring the mixed and ground material obtained in the step S2 into a press, carrying out green body forming, obtaining a formed blank, and standing the green body for 12-48 hours.

And S4, sintering the molded blank in the step S3 at the temperature of 700-2600 ℃ for 72-480 hours to obtain the initial sintered blank of the graphite electrode.

Example one produced 600mm by 2100mm two dip three bake process graphite electrodes with the indices shown in table 1 below:

TABLE 1

Example two

S1, selecting aggregates, namely selecting 5-80 parts of asphalt needle-shaped calcined coke sand with the thickness of 0.1-5mm, 15-50 parts of petroleum calcined coke powder with the thickness of 0.05-0.088mm, 0.05-20 parts of graphite and 0.1-5 parts of iron oxide red; 0.2-20 parts of phenolic resin and 1-3 parts of additive are additionally selected.

And S2, uniformly mixing the raw materials in the step S1 to obtain the mixed and ground material with the instant temperature of 10-80 ℃.

And S3, pouring the mixed and ground material obtained in the step S2 into a press, carrying out green body forming, obtaining a formed blank, and standing the green body for 12-48 hours.

S4, sintering the molded blank obtained in the step S3 at the temperature of 700-2600 ℃ for 72-480 hours to obtain an initial sintered blank of the graphite electrode;

the indices for the 600mm by 2100mm two-dip three-bake process graphite electrode produced in example two are shown in table 2 below:

TABLE 2

EXAMPLE III

S1, selecting aggregates, namely selecting 5-80 parts of petroleum calcined coke sand with the thickness of 0.1-5mm, 15-50 parts of asphalt needle-shaped calcined coke powder with the thickness of 0.05-0.088mm, 0.05-20 parts of graphite and 0.1-5 parts of iron oxide red; 0.2-20 parts of phenolic resin is additionally selected.

And S2, uniformly mixing the raw materials in the step S1 to obtain the mixed and ground material with the instant temperature of 10-80 ℃.

And S3, pouring the mixed and ground material obtained in the step S2 into a press, carrying out green body forming, obtaining a formed blank, and standing the green body for 12-48 hours.

And S4, sintering the molded blank in the step S3 at the temperature of 700-2600 ℃ for 72-480 hours to obtain the initial sintered blank of the graphite electrode.

The 600mm by 2100mm two-dip three-bake process graphite electrode produced in example three was indexed as follows:

TABLE 3

Example four

S1, selecting aggregates, selecting 5-80 parts of petroleum calcined coke sand with the thickness of 0.1-5mm, 15-50 parts of petroleum calcined coke powder with the thickness of 0.05-0.088mm, 0.05-20 parts of graphite and 0.1-5 parts of iron oxide red; 0.2-20 parts of phenolic resin is additionally selected.

And S2, uniformly mixing the raw materials in the step S1 to obtain the mixed and ground material with the instant temperature of 10-80 ℃.

And S3, pouring the mixed and ground material obtained in the step S2 into a press, carrying out green body forming, obtaining a formed blank, and standing the green body for 12-48 hours.

And S4, sintering the molded blank in the step S3 at the temperature of 700-2600 ℃ for 72-480 hours to obtain the initial sintered blank of the graphite electrode.

The indices for the 600mm by 2100mm two-dip three-bake process graphite electrode produced in example four are shown in table 4 below:

TABLE 4

EXAMPLE five

S1, selecting aggregate, namely selecting 0.1-5mm petroleum calcined coke sand and 5-80 parts of 0.1-5mm asphalt needle-shaped calcined coke sand, selecting 0.05-0.088mm asphalt needle-shaped calcined coke powder and 15-50 parts of 0.05-0.088mm petroleum calcined coke powder, selecting 0.05-20 parts of graphite and selecting 0.1-5 parts of iron oxide red; 0.2-20 parts of phenolic resin and 1-3 parts of additive are additionally selected.

And S2, uniformly mixing the raw materials in the step S1 to obtain the mixed and ground material with the instant temperature of 10-80 ℃.

And S3, pouring the mixed and ground material obtained in the step S2 into a press, carrying out green body forming, obtaining a formed blank, and standing the green body for 12-48 hours.

S4, sintering the molded blank obtained in the step S3 at the temperature of 700-2600 ℃ for 72-480 hours to obtain an initial sintered blank of the graphite electrode;

the indices for the 600mm by 2100mm two-dip three-bake process graphite electrode produced in example five are shown in table 5 below:

TABLE 5

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.