WO2012161410A1

WO2012161410A1 - Method for manufacturing a graphite block

Info

Publication number: WO2012161410A1
Application number: PCT/KR2012/001426
Authority: WO
Inventors: 노재승; 강동수; 이광주; 김재홍; 김범준; 이재호; 서승국; 안재상; 이현용
Original assignee: 금오공과대학교 산학협력단
Priority date: 2011-05-26
Filing date: 2012-02-24
Publication date: 2012-11-29
Also published as: KR20120131705A; KR101249647B1

Abstract

The present invention relates to a method for manufacturing a graphite block, and more particularly, the present invention comprises the steps of: mixing a graphite powder functioning as a filler with a coal tar pitch functioning as a binder, pulverizing the thus-obtained mixed raw material, injecting the pulverized material into a mold and performing compression molding to form a molding object, impregnating the molding object into an impregnating material, and heating the impregnated molding object.

Description

Manufacturing method of graphite block

The present invention relates to a method for producing a graphite block, and more particularly, to a method for producing a graphite block using a graphite powder as a filler and a coal tar pitch as a binder is heat-treated at a low temperature.

In general, artificial graphite products include artificial graphite electrode rods, metallurgy, electrochemicals such as electric discharge machining electrodes, electric resistances such as resistance heating elements, mechanical bearings such as bearing and mechanical seals, chemical structures such as heat exchangers, carbon lead, etc. , Chemicals such as activated carbon and ACF, reactors such as moderators, reflectors, and shielding agents, and aerospaces such as nose cones, nozzles, and the like, and about 60% of artificial graphite products account for artificial graphite electrodes.

The manufacturing method of the artificial graphite products used for such various uses is not radically different from the manufacturing method of the general carbon material, but it is possible to manufacture a product having various characteristics according to the type of raw materials used, the setting of the manufacturing conditions.

The general manufacturing process of artificial graphite electrode is pulverization and classification of raw material {coke (needle coke)}, selection of the mixing ratio according to the required characteristics of the product and kneading with the binder, extrusion of the kneaded material, uniaxial, isotropic molding, firing of the molded product, impregnation And refired, graphitized, processed and inspected to form the final product.

As for the characteristics and precautions of each process, the selection of raw material coke is very important. In the manufacture of all carbon materials, it is essential to select raw materials in consideration of the properties required for the final product, and much attention must be paid to quality control as they are used under harsh conditions in artificial graphite electrodes and other products.

Coke as a raw material should be blended according to the particle size ratio of the raw material to express the properties of the product required prior to mixing with the binder, for this purpose is to perform the net chain and classification of the raw material coke.

In general, when pulverizing coke, the grinding conditions and pulverizer are selected to maximize the characteristics of acicular coke in consideration of the pulverization characteristics of carbonaceous raw materials having high abrasion, hygroscopicity, lubricity and impact strength, and low specific gravity and elastic modulus. It is desirable to. Coke formulated by the appropriate blending ratio is not binding force between the particles, so mixing with the binder to bind them is essential.

The mixing of coke and binder is mainly used for kneading, and it is important to mix the binder so that the binder can be uniformly dispersed and coated on the surface of coke particles through kneading. And conditions such as kneading temperature should be made. However, excessive kneading in the kneading process causes a problem of lowering the physical properties of the product or lowering the coking force by closing the voids in the coke particles, and therefore, much care must be taken in selecting the kneading conditions.

The kneaded material that has been kneaded is molded to meet the purpose by using a molding machine. As the method for forming artificial graphite products, extrusion molding is performed in the case of artificial graphite electrode rods, but compression molding or isotropic molding (CIP) is used for some special applications and small carbon molded bodies. After the mixing is completed in the kneader, the mixture is appropriately shaped according to the molding method and heated to an appropriate temperature during molding. At this time, the degassing to appropriately remove the generated gas component is performed. When degassing occurs in the degassing process, care must be taken because the generated gas remains in the molded body during the extrusion process, which may cause cracks in the molded body during the post-firing process.

After that, the molded body is subjected to the firing process, impregnation and refiring process, and the firing conditions should be managed in various ways according to the density, size, type, etc. of the molded body. In the general firing process, oil or gas is used as an energy source, and a method of processing a large amount of products at the same time is adopted. Therefore, appropriately select fillers and filling methods for preventing occurrence of temperature variation during firing and prevention of oxidation. shall.

In the primary fired body, a large amount of pores occur inside and outside due to the release of gas generated by a low molecular weight component and decomposition reaction in the molded body, and thus, a density decrease occurs. Therefore, in order to meet the required physical properties, the impregnation process is performed by the impregnating agent, and the selection of the impregnating agent and the impregnation conditions for improving the efficiency in the impregnation process is important. Products that have been impregnated with the impregnant are subjected to a refiring process, which requires a shorter firing time than the normal firing process. Such firing, impregnation, and refiring process is a process that consumes a lot of energy, and it is required to develop a short-time firing technology for reducing energy consumption.

The refired molded body is subjected to a graphitization process for electrical properties and tissue development. The graphitization process consumes a large amount of energy and uses electric power as an energy source. Therefore, the graphitization process is the most costly process for manufacturing artificial graphite products and at the same time, it is a process for determining the quality of the final product. Therefore, the improvement of energy efficiency in the graphitization process and the development of a new graphitization technology are not overlooked even in the aspect of securing the price competitiveness of the product, and thus, many efforts have been made by the manufacturers.

It is an object of the present invention to provide a method for producing a graphite block having excellent physical properties by using graphite powder as a filler and using a mixture of tar and toluene as an impregnating agent.

Another object of the present invention is to provide a method for producing a graphite block excellent in energy consumption efficiency can proceed to a low temperature during the heat treatment process.

As a specific means for achieving the above object, the present invention is a raw material mixing step of mixing the graphite powder and coal tar pitch, pulverization step of pulverizing the mixed raw material, injecting the pulverized raw material into a mold and compression molding to produce a molded body It provides a method for producing a graphite block, comprising a molded article manufacturing step, an impregnating step of impregnating the molded body with the impregnating agent and a heat treatment step of heating the molded body after the impregnation step.

According to a preferred feature of the invention, the raw material mixing step is to be made by mixing 75 to 85 parts by weight of graphite powder and 15 to 25 parts by weight of coal tar pitch at a temperature of 200 to 300 ℃.

According to a more preferred feature of the invention, the molded article manufacturing step is to be made by injecting the pulverized raw material into a mold and compressed to a pressure of 100 to 125Mpa.

According to a more preferred feature of the invention, the impregnation step is heated to a temperature of 500 to 600 ℃ for 1 to 2 hours, and after impregnating the heated molded body in the container containing the impregnating agent, the pressure in the container It is assumed that the process of lowering to 0.1 Torr is repeated a number of times.

According to a still further preferred feature of the present invention, the impregnating agent is to be composed of 45 to 55 parts by weight of coal tar and 45 to 55 parts by weight of toluene.

According to a further preferred feature of the invention, the heat treatment step is to be made by heating the molded body after the impregnation step for 1 to 2 hours at a temperature of 1500 to 1600 ℃.

The method for producing a graphite block according to the present invention has an excellent effect of providing a graphite block having excellent physical properties by using graphite powder as a filler and a tar and toluene mixture as an impregnating agent.

In addition, it is possible to heat treatment at a low temperature exhibits an excellent effect of providing a method for producing a graphite block excellent in energy consumption efficiency.

1 is a flowchart illustrating a method of manufacturing a graphite block according to the present invention.

Figure 2 is an external view showing a graphite block manufactured by the method for producing a graphite block according to the present invention.

In the following, preferred embodiments of the present invention and the physical properties of each component will be described in detail, which is intended to explain in detail enough to be able to easily carry out the invention by one of ordinary skill in the art, This does not mean that the technical spirit and scope of the present invention is limited.

In the method for producing a graphite block according to the present invention, as shown in Figure 1, the raw material mixing step of mixing the graphite powder and coal tar pitch (S101), the grinding step of grinding the mixed raw material (S103), the pulverized raw material mold Injection molding and compression molding to produce a molded body (S105), an impregnating step (S107) of impregnating the molded body into the impregnating agent and a heat treatment step (S109) of heating the molded body after the impregnation step (S107). .

The raw material mixing step (S101) is a step of mixing the graphite powder and coal tar pitch is made by mixing 75 to 85 parts by weight of graphite powder and 15 to 25 parts by weight of coal tar pitch at a temperature of 200 to 300 ℃, wherein the graphite powder It serves as a silver filler, and the coal tar pitch serves as a binder.

At this time, the graphite powder is preferably used for 1 hour with a sieve of 53 to 212㎛ (sieve).

The raw material mixed with the coal powder and coal tar pitch mixed as described above is kneaded in a kneader for 3 hours and then mixed at a temperature of 200 to 300 ° C. for 30 minutes, and mixed at a temperature of 200 to 300 ° C. for 30 minutes. Coal tar pitch is uniformly applied to the surface of the.

When using coke as a filler, as in the prior art, since the coke crystallinity is lower than that of graphite, the heat treatment temperature should be performed at a temperature of 2000 ° C. However, when using graphite powder having a higher crystallinity than coke as a filler, 1500 to 1600 Heat treatment is possible at a temperature of ℃, the energy consumption efficiency is increased in the manufacturing process of the graphite block.

The grinding step (S103) is a step of grinding the mixed raw materials, the graphite powder is agglomerated by the coal tar pitch as a binder component used in the raw material mixing step (S101), the step of grinding the aggregated raw materials using a grinder All.

The molded article manufacturing step (S105) is a step of manufacturing a molded body by injecting the crushed raw material into a mold and compression molding, injecting the crushed raw material into a mold and compression molding at a pressure of 100 to 125Mpa to produce a molded body in the form of a block Step.

The impregnation step (S107) is a step of impregnating the molded body into the impregnant, and heating the molded body at a temperature of 500 to 600 ° C. for 1 to 2 hours, and after impregnating the heated molded body into a container containing the impregnant. Using a pressure reducer, the process of reducing the pressure in the vessel to 0.1 Torr is repeated three times.

When heated at a temperature of 500 to 600 ℃ as described above for 1 to 2 hours, the moisture contained in the pores formed in the graphite powder is removed to improve the impregnation efficiency.

The impregnating agent is made by mixing 50 parts by weight of coal tar and 50 parts by weight of toluene, the existing impregnating agent was capable of impregnation in the state heated to a temperature of 150 to 200 ℃, the impregnation agent used in the present invention is also used at room temperature This is possible.

When impregnating the molded body in the coal tar at room temperature, the impregnating agent is not added to the pores formed inside the molded body due to the inherent high viscosity of the coal tar, so that the impregnation process is carried out at room temperature using a method of mixing toluene with coal tar to lower the viscosity of the coal tar. This made it possible.

The use of such an impregnant not only shows the effect of providing the graphite block having excellent physical properties, but also shows the effect of lowering the manufacturing process cost.

In addition, in order to lower the pressure in the container by using a pressure reducer to reduce the pressure in the container to 0.1 Torr as described above, the impregnating agent may be easily added to the pores formed in the molded body due to the low pressure in the container.

At this time, the container to be used may be any shape as long as the deformation is free according to the change of the internal vacuum degree, such as a plastic pack having excellent strength, and when the vacuum degree is lowered to 0.1 Torr as described above, the molded body is taken out of the container and again 500 to 600 ° C. This process is repeated three times in a manner of heating to a temperature of, but repeating three times improves the efficiency of the impregnating agent penetrating into the pores present in the molded body.

The heat treatment step (S109) is a step of heating the molded body through the impregnation step (S107), it is made by heating the molded body through the impregnation step (S107) for 1 to 2 hours at a temperature of 1500 to 1600 ℃, crystal Since graphite powder having high properties is used, heat treatment is possible even at a temperature of 1500 to 1600 ° C., thereby providing a graphite block manufacturing method having a very high energy consumption efficiency.

When the heat treatment step (S109) is passed, the graphite block has excellent physical properties and low manufacturing cost.

Hereinafter, a method for producing a graphite block according to the present invention and the physical properties of the graphite block produced by the production method will be described with reference to Examples.

160 g of graphite powder and 40 g of coal tar pitch, which were sieved for 1 hour with 100 μm, were added to the kneader and kneaded for 3 hours, and then the kneader was heated to a temperature of 200 ° C. and mixed for 30 minutes. After decomposing and crushing the raw materials into a compression molding machine, they were compression molded at a pressure of 125 Mpa, and the compacted molded body was heated at a temperature of 600 ° C. for 1 hour, followed by 500 g of coal tar and toluene (TOLUENE (Methylbenzene) of DAEJUNG CHEMICALS & METALS). } After impregnating the molded product in the plastic pack containing 1000g of impregnating agent mixed with 500g and sealing the plastic pack, the pressure inside the plastic pack is reduced to 0.1 Torr using a pressure reducer. Repeat the steps of heating, impregnating and depressurizing to a temperature of ℃ 3 times, and when the three times are completed, take out the molded body from the plastic pack at 1 o'clock to 1500 ℃. It was prepared for the graphite block by heating.

The density, porosity, and compressive strength of the graphite blocks prepared through the above examples are measured and shown in Table 1 below.

(However, density and porosity were measured using AG204 model of Mettler-toledo, and compressive strength was measured using Instron's universal testing machine 4400 Series.)

Table 1

As shown in Table 1 above, the method for producing a graphite block according to the present invention not only provides a graphite block having excellent physical properties, but also has a low manufacturing cost and an excellent heat consumption efficiency.

Claims

Raw material mixing step of mixing the graphite powder and coal tar pitch;

A grinding step of grinding the mixed raw materials;

A molded article manufacturing step of preparing a molded article by injecting the pulverized raw material into a mold and compression molding;

An impregnation step of impregnating the molded body with an impregnation agent; And

And a heat treatment step of heating the formed body which has undergone the impregnation step.
The method according to claim 1,

The raw material mixing step is a graphite block manufacturing method characterized in that the mixture is made by mixing 75 to 85 parts by weight and 15 to 25 parts by weight of coal tar pitch at a temperature of 200 to 300 ℃.
The method according to claim 1,

The molded article manufacturing step is a method of producing a graphite block, characterized in that by injecting the pulverized raw material into a mold and compressed to a pressure of 100 to 125Mpa.
The method according to claim 1,

In the impregnation step, the molded body is heated to a temperature of 500 to 600 ° C. for 1 to 2 hours, the heated molded product is impregnated in a container containing an impregnant, and then the pressure in the container is lowered to 0.1 Torr a plurality of times. Method for producing a graphite block, characterized in that it is made repeatedly.
The method according to claim 4,

The impregnating agent is 45 to 55 parts by weight of coal tar and 45 to 55 parts by weight of toluene manufacturing method of the graphite block.
The method according to claim 1,

The heat treatment step is a method for producing a graphite block, characterized in that by heating the molded body after the impregnation step for 1 to 2 hours at a temperature of 1500 to 1600 ℃.