KR20240020287A - Electrode material for electrode for saf using isotropic coke and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a method of manufacturing an electrode material for an electrode using isotropic coke and to an electrode material manufactured thereby. When analyzing elements, C: 95.00-99.00%, H: 0.01-0.05%, N: 0.5-1.2 in weight percent. %, S: 0.15~0.50%, Ash (ash): 0.2~0.5%, VM (volatile matter): 1~5%, Fixed Carbon (carbon yield): 95~98% in weight % when analyzing industrial coal. When analyzing satisfactory aggregates and elements, C: 90-95% by weight, H: 2-6%, N: 1-4%, S: 0.2-1.0%, and Ash (ash) by weight when analyzing industrial coal. : 0.10~0.40%, VM (volatile content): 50~59.8%, Fixed Carbon (carbon yield) 40~49.8%, softening point: mixing pitch that satisfies the conditions of 75~125℃; and kneading steps.

Description

Electrode material used for SAF electrode using isotropic coke and manufacturing method thereof {ELECTRODE MATERIAL FOR ELECTRODE FOR SAF USING ISOTROPIC COKE AND MANUFACTURING METHOD THEREOF}

The present invention relates to a method of manufacturing an electrode material for an electrode using isotropic coke and to an electrode material manufactured thereby. More specifically, the present invention relates to an isotropic electrode material having higher mechanical properties, carbon content, etc. compared to an electrode material using existing calcined anthracite coal as an aggregate. When electrode materials using coke as an aggregate and electrode materials are used as electrodes, SAF (Submerged Arc) has characteristics such as high mechanical strength, low electrical resistivity, high carbon yield, and low ash content after self-firing. This relates to electrode materials suitable for self-firing electrodes for furnaces.

Electrodes for electric furnaces, such as artificial graphite and carbon electrodes, and various heating elements, such as welding rods and resistance heating elements, are used to convert electrical energy into heat energy, and electrodes are mainly used by arc heat generated between electrodes or between electrodes and objects to be treated. It is used to heat and melt the object to be treated. Artificial graphite electrodes are mainly used in arc furnaces for electric steelmaking, but are also widely used in electric arc furnaces for manufacturing various products such as non-ferrous metals, ferroalloys, and carbon disulfide.

Among them, the SAF (Submerged Arc Furnaces) electric furnace, which is widely used in the production of ferroalloys, produces a large amount of thermal-plasma heat by applying electricity to a graphite electrode to melt raw materials. Meanwhile, unlike electrodes for steelmaking, SAF electrodes are melted by inserting electrode materials, filled with their own weight, and fired during use to serve as electrodes. Because of this, self-firing and continuous operation are possible, so it can be viewed as a self-baking continuous electrode type. The Soderberg type is a completely self-baking type made of iron plate, etc., and the case is a firing electrode. There is a diamagnetic firing method that is made by combining segments and filling the center with electrode material to continue sequentially.

The present invention was developed to improve existing electrode materials. Calcined anthracite, which is widely used as an aggregate in existing electrode materials, is carbon with a high ash content containing SiO ₂ , Al ₂ O ₃ , CaO, MgO, etc. It's a material. If the ash content is high, the fixed carbon yield naturally decreases, which affects the physical properties of the electrode material and the electrode molded body after firing. Therefore, the present invention provides a method of manufacturing a high-carbon electrode material with a low ash content and high carbonation yield by replacing calcined anthracite, which is a conventional aggregate, with isostatic coke, a high-strength, high-carbon material.

In order to achieve the above object, the method for manufacturing an electrode material according to an embodiment of the present invention is, upon elemental analysis, C: 95.00-99.00%, H: 0.01-0.05%, N: 0.5-1.2%, S: 0.15~0.50%, when analyzing industrial coal, aggregate that satisfies the following conditions in weight percentage: Ash (ash): 0.2~0.5%, VM (volatile matter): 1~5%, Fixed Carbon (carbon yield): 95~98% When analyzing elements, C: 90-95% by weight, H: 2-6%, N: 1-4%, S: 0.2-1.0%, and when analyzing industrial coal, Ash (ash) by weight: 0.10 A step of mixing pitch that satisfies the following conditions: ~0.40%, VM (volatile matter): 50~59.8%, Fixed Carbon (carbon yield) 40~49.8%, softening point: 75~125℃; and kneading steps.

In addition, in the method of manufacturing an electrode material according to an embodiment of the present invention, the particle size distribution of the aggregate is expressed in weight%, exceeding 11.2 mm: 5 to 10%, 11.2 mm to 1 mm: 35 to 70%, and less than 1 mm: 20 It could be ~40%.

In addition, in the method of manufacturing an electrode material according to an embodiment of the present invention, the pitch mixed in the mixing step may be 20 to 30% by weight.

Additionally, in the method of manufacturing an electrode material according to an embodiment of the present invention, the kneading step may be a step of reforming the electrode material by kneading at a temperature of 200 to 400° C. for 3 to 6 hours.

Additionally, the electrode material according to an embodiment of the present invention may have a plasticity of 10 to 20% or more.

Additionally, the molded body of the electrode material according to an embodiment of the present invention may have a density of 1.25 to 1.30 g/cm ³ .

Additionally, the molded body of the electrode material according to an embodiment of the present invention may have an electrical resistivity of 70 to 100 μΩm.

Additionally, the molded body of the electrode material according to an embodiment of the present invention may have a compressive strength of 5.0 MPa or more.

Additionally, the molded body of the electrode material according to an embodiment of the present invention may have a bending strength of 3.0 MPa or more.

According to the electrode material for SAF self-firing electrode using isotropic coke and its manufacturing method according to the present invention, the Ash (ash) content is reduced by 85-90% and the VM (volatile matter) content is reduced by 30% compared to the electrode material using existing calcined anthracite as aggregate. Reduced by ~40%, Fixed Carbon (carbon yield) increased by 5~10%, Electrical resistivity reduced by 10~20%, Compressive strength increased by 0~10%, Bending strength increased by 10~40%. Although it is high carbon, it is similar to existing products. Compared to other methods, high-quality electrode materials with improved physical properties can be provided.

Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention may be modified into various other forms, and the technical idea of the present invention is not limited to the embodiments described below. Additionally, the embodiments of the present invention are provided to more completely explain the present invention to those with average knowledge in the relevant technical field.

The terms used in this application are only used to describe specific examples. Therefore, for example, a singular expression includes a plural expression, unless the context clearly requires it to be singular. In addition, terms such as “comprise” or “comprise” used in the present application are used to clearly indicate the presence of features, steps, functions, components, or combinations thereof described in the specification, and are not used to indicate other features. It should be noted that it is not used to preliminarily rule out the existence of any elements, steps, functions, components, or combinations thereof.

Meanwhile, unless otherwise defined, all terms used in this specification should be viewed as having the same meaning as generally understood by those skilled in the art to which the present invention pertains. Therefore, unless clearly defined in this specification, specific terms should not be interpreted in an overly idealistic or formal sense. For example, in this specification, singular expressions include plural expressions unless the context clearly dictates otherwise.

In addition, in this specification, "about", "substantially", etc. are used in the meaning of or close to that value when manufacturing and material tolerances inherent in the stated meaning are presented, and are used accurately to aid understanding of the present invention. It is used to prevent unscrupulous infringers from unfairly exploiting disclosures where absolute figures are mentioned. The embodiments described in this specification and the configuration shown in the drawings are preferred examples of the disclosed invention, and at the time of filing this application, there may be various modifications that can replace the embodiments and drawings in this specification.

Additionally, the terms used herein are used to describe embodiments and are not intended to limit and/or limit the disclosed invention. Additionally, each step may be performed differently from the specified order unless the specific order is clearly stated in the context.

Hereinafter, the electrode material for SAF electrode and its manufacturing method using isotropic coke according to an embodiment of the present invention will be described in detail.

The method for manufacturing an electrode material according to an embodiment of the present invention, upon elemental analysis, C: 95.00-99.00%, H: 0.01-0.05%, N: 0.5-1.2%, S: 0.15-0.50%, industrial When analyzing coal, when analyzing aggregates and elements that satisfy the conditions of Ash (ash): 0.2~0.5%, VM (volatile matter): 1~5%, and Fixed Carbon (carbon yield): 95~98% by weight, the weight C: 90~95% in %, H: 2~6%, N: 1~4%, S: 0.2~1.0%, when analyzing industrial coal, Ash (ash) in % by weight: 0.10~0.40%, VM( A step of mixing pitch that satisfies the following conditions: Volatile content: 50~59.8%, Fixed Carbon (carbon yield) 40~49.8%, softening point: 75~125℃; and

It includes a kneading step.

The manufacturing method of the electrode material of the present invention uses isostatic coke as an aggregate instead of calcined anthracite, which is used as an existing aggregate. Isostatic coke has higher strength, high carbonation yield, and low ash content compared to calcined anthracite. On the other hand, existing calcined anthracite aggregates have a low carbonation yield because ash remains after firing due to the CaO and MgO content of about 2 to 5%.

In addition, in the method of manufacturing an electrode material according to an embodiment of the present invention, the particle size distribution of the aggregate is expressed in weight%, exceeding 11.2 mm: 5 to 10%, 11.2 mm to 1 mm: 35 to 70%, and less than 1 mm: 20 It could be ~40%. The particle size distribution of the aggregate is an important factor that determines the strength of the molded body in the future, and the fine particles of 1 mm or less are a factor that can maintain the bond with the pitch and fluidity.

In addition, in the method of manufacturing an electrode material according to an embodiment of the present invention, the pitch mixed in the mixing step may be 20 to 30% by weight. Additionally, in the method of manufacturing an electrode material according to an embodiment of the present invention, the kneading step may be a step of reforming the electrode material by kneading at a temperature of 200 to 400° C. for 3 to 6 hours. After kneading, it is placed in a mold, molded to a certain size, and then solidified.

As described above, after mixing aggregate and pitch, a briquette molded body is manufactured by mixing evenly through a kneading process and reforming the mixture of aggregate and pitch. In a self-firing type electric furnace, electrode material is put into the furnace and is filled and fired due to heat and its own load, thereby serving as an electrode. At this time, plasticity, one of the factors to be considered in the filling and firing process, is a very important factor. If plasticity is good, it softens well, but due to high fluidity, it may not be fired properly during electrode formation and may spill out. If plasticity is bad, it cannot be filled sufficiently and pores remain, causing a decrease in the physical properties of the electrode molded body after firing. Therefore, in order to make a briquette molded body with optimal plasticity, appropriate modification of the kneaded product is necessary, and the plasticity is measured through the change in diameter before and after heat treatment by raising the temperature to 200~400℃. At this time, the plasticity value must be 10 to 20% to meet optimal conditions when manufacturing electrode molded bodies. Kneading temperature and time conditions are important factors affecting plasticity, and if the temperature is lower than the temperature described in the manufacturing method of the present invention or the kneading time is short, the pitch is not modified and plasticity becomes too high, and the shape is not formed and molding is not possible. . In addition, if the temperature is high or the kneading time is too long, pores created by solidifying too quickly have a negative effect on physical properties such as reduced density, increased electrical resistivity, and reduced strength.

In addition, the kneading temperature and time form an appropriate softening point of the mixture (electrode material) of pitch and aggregate with a low softening point of 75 to 125°C, so that if the softening point is too low when going through the melt phase during the manufacture of electrodes, the electrode material may be damaged. It is necessary to prevent the problem of loss of the electrode by flowing down, and if the softening point is too high, the filling is not sufficient and pores are formed, which adversely affects the physical properties of the electrode after firing.

Therefore, the electrode material according to an embodiment of the present invention manufactured by the above-described method may have a plasticity of 10 to 20%.

Additionally, the molded body manufactured by firing the electrode material may have a density of 1.25 to 1.30 g/cm ³ . That is, when the density of the molded body according to the present invention satisfies 1.25 to 1.30 g/cm ^{3 ,} the filling is good and pores that may adversely affect the electrical and mechanical properties can be reduced.

Additionally, the molded body manufactured by firing the electrode material may have an electrical resistivity of 70 to 100 μΩm. That is, the molded body according to the present invention has an electrical resistivity that satisfies the above range, so it can exhibit electrical characteristics suitable for use as an electrode.

In addition, the molded body manufactured by firing the electrode material may have a compressive strength of 5.0 MPa or more and a bending strength of 3.0 MPa or more. That is, the molded body according to the present invention satisfies the above range of strength and can withstand various stresses such as gravity from top to bottom and the load of the electrode itself when used as an electrode.

Hereinafter, the present invention will be described in more detail through examples. However, the description of these examples is only for illustrating the implementation of the present invention, and the present invention is not limited by the description of these examples. This is because the scope of rights of the present invention is determined by matters stated in the patent claims and matters reasonably inferred therefrom.

[Example]

Particle size distribution of aggregate (isotropic coke) in weight%, over 11.2mm: 5~10%, 11.2mm~1mm: 35~70%, and less than 1mm: 20~40%, pitch in weight% The raw materials mixed using pitch of 20~30% and softening point of 75~125℃ were kneaded at 200~400℃ for 3~6 hours, and the elemental analysis and industrial coal analysis of the isotropic coke used are shown in Table 1 below. indicated.

division Elemental analysis (weight%) Industrial coal analysis (% by weight) C H N S ASH VM F.C.
(Fixed Carbon) Invention material 1 Isostatic coke 1 98.28 0.02 0.77 0.33 0.44 2.38 97.13 Invention material 2 Isostatic coke 2 98.58 0.00 0.55 0.37 0.41 2.30 97.24 Comparative Good 1 Coke by-product 1 95.94 0.03 0.66 0.36 0.38 1.95 97.62 Comparative Good 2 Coke by-product 2 91.43 1.91 1.16 0.38 4.23 6.74 88.7 Comparative Goods 3 calcined anthracite 96.39 0.23 0.44 0.32 4.26 4.08 91.41

Table 1 shows the results of elemental analysis of isostatic coke and industrial coal analysis used as aggregate for electrode materials. It can be confirmed that isotropic coke suitable as an aggregate of the present invention satisfies all the scope of the present invention and has a high carbonization yield. The particle size distribution of this isostatic coke was mixed in weight percent, greater than 11.2 mm: 5 to 10%, 11.2 mm to 1 mm: 35 to 70%, and less than 1 mm: 20 to 40%, and used as aggregate.

division Ash
% VM
% Fixed Carbon
% Yeonhwa branch
℃ Invention Binder 1 pitch 1 0.26 56.76 41.70 90 invention binder 2 pitch 2 0.21 56.92 42.18 90 Comparison Binder 1 pitch 3 0.04 56.06 43.90 120 Comparison Binder 2 pitch 4 0.56 45.97 53.53 120

Table 2 above shows the results of industrial coal analysis of the pitch used as the pitch of the electrode material. It can be seen that the pitch suitable as the aggregate of the present invention satisfies the scope of the present invention, while the pitch of the comparative example does not satisfy the range of Ash and/or the range of VM. At this time, since the softening point affects the fluidity and plasticity of the mixed product during kneading, pitch as a binder was mixed with aggregate in a ratio of 7:3 to 8:2 and then kneaded to produce electrode materials.

division aggregate bookbinder Kneading temperature Kneading time Electrode material (before firing) Ash
% VM
% Fixed Carbon
% plasticity
% Invention Example 1 Isostatic coke 1 pitch 1 O O 0.21 12.40 87.40 19.59 Invention Example 2 Isostatic coke 2 pitch 2 O O 0.14 13.32 86.28 18.56 Comparative Example 1 Isostatic coke 1 pitch 1 Х O 0.31 11.70 87.98 125.47 Comparative Example 2 Isostatic coke 1 pitch 2 Х O 0.08 6.69 92.72 130.14 Comparative Example 3 Isostatic coke 2 pitch 2 Х O 0.44 7.44 91.91 118.22 Comparative Example 4 Isostatic coke 1 pitch 1 O Х 3.37 11.09 85.54 67.71 Comparative Example 5 Isostatic coke 1 pitch 2 O Х 3.92 10.38 88.13 58.63 Comparative Example 6 Isostatic coke 2 pitch 2 O Х 3.78 10.66 85.08 62.19

Table 3 above shows the physical properties of the electrode material (before firing) according to kneading conditions. If the kneading temperature and kneading time conditions of the present invention are satisfied, it is indicated as O, and if it is not satisfied, it is indicated as ×. If the kneading temperature is too low, the plasticity is measured to be too high, and if the kneading time is too short, the plasticity is also measured to be high. Therefore, inventive examples 1 and 2, in which the kneading temperature and training time both satisfy the range of the present invention, have a softening point and plasticity It was confirmed that Comparative Examples 1 to 6, which all satisfied the scope of the present invention but did not satisfy the kneading temperature or kneading time, had plasticity exceeding 20%. When producing the electrode material, the same overhead stirrer and heating mantle were used for kneading. After each kneading process, the electrode material was placed in a cylindrical mold with a diameter of 40 mm to produce a plasticity specimen. When measuring the plasticity, the plasticity test was performed four times. The measurements were made and the average values are shown in Table 4 below.

division aggregate bookbinder Kneading temperature Kneading time Molded body of electrode material Apparent density
(g/cm3 ⁾ electrical resistivity
(μΩm) compressive strength
(MPa) bending strength
(MPa) Invention Example 1 Isostatic coke 1 pitch 1 O O 1.255 90.65 6.89 3.62 Invention Example 2 Isostatic coke 2 pitch 2 O O 1.250 99.00 5.54 3.59 Comparative Example 1 Isostatic coke 1 pitch 1 Х Х 1.310 287.83 1.20 2.43 Comparative Example 7 Calcined anthracite coal pitch 1 O O 1.210 109.31 6.86 2.74 Comparative Example 8 Calcined anthracite coal pitch 1 Х Х 1.330 240.23 1.40 0.69

After the electrode material mixing process, an oval-shaped briquette with a diameter of 4cm was produced using a briquette molding machine, and then placed in a 120Φ stainless steel cylindrical mold and fired. The firing conditions were 1,000°C per minute (temperature rise 2°C/min, maintained for 1 hour, N ₂ atmosphere). The physical properties after firing were measured in accordance with the standards of KS L 3409 (Testing Method for Physical Properties of Graphite Materials), and the average value was measured by measuring samples 5 times for each condition and is shown in Table 4. That is, isotropic according to the present invention. The molded body manufactured by mixing coke and pitch and firing the electrode material prepared under the kneading conditions according to the present invention had a density of 1.25 to 1.30 g/cm ³ , an electrical resistivity of 70 to 100 μΩm, and a compressive strength of 5.0. It was confirmed that it was more than MPa, the bending strength was more than 3.0 MPa, and the plasticity was 10-20%. On the other hand, when the aggregate was calcined anthracite or the kneading conditions were not suitable, it was confirmed that the physical properties of the electrode material molded body did not satisfy the scope of the present invention.

In the foregoing, exemplary embodiments of the present invention have been described, but the present invention is not limited thereto, and a person skilled in the art will recognize the present invention within the scope and spirit of the following claims. You will understand that various changes and modifications are possible.

Claims (9)

When analyzing elements, C: 95.00-99.00% by weight, H: 0.01-0.05%, N: 0.5-1.2%, S: 0.15-0.50%, and when analyzing industrial coal, Ash (ash) by weight: 0.2 When analyzing aggregates and elements that meet the conditions of ~0.5%, VM (volatile matter): 1~5%, Fixed Carbon (carbon yield): 95~98%, C: 90~95%, H: 2~ in weight% 6%, N: 1~4%, S: 0.2~1.0%, Ash (ash) in weight% when analyzing industrial coal: 0.10~0.40%, VM (volatile matter): 50~59.8%, Fixed Carbon (carbon yield) Mixing a pitch that satisfies the conditions of 40~49.8%, softening point: 75~125℃; and
kneading step;
A method of manufacturing an electrode material comprising: In claim 1,
The particle size distribution of the aggregate is in weight%, greater than 11.2 mm: 5 to 10%, 11.2 mm to 1 mm: 35 to 70%, and less than 1 mm: 20 to 40%. In claim 1,
A method for producing an electrode material, characterized in that the pitch mixed in the mixing step is 20 to 30% by weight. In claim 1,
A method of manufacturing an electrode material, characterized in that the kneading step is a step of reforming by kneading at a temperature of 200 to 400 ° C. for 3 to 6 hours. The electrode material manufactured by the manufacturing method of claim 1 is characterized in that the plasticity is 10 to 20%. A molded body of an electrode material, characterized in that the density is 1.25 to 1.30 g/cm ³ by firing the electrode material of claim 5. A molded body of an electrode material, characterized in that the electrical resistivity is 70 to 100 μΩm by firing the electrode material of claim 5. A molded body of an electrode material obtained by firing the electrode material of claim 5 and having a compressive strength of 5.0 MPa or more. A molded body of an electrode material obtained by firing the electrode material of claim 5 and having a bending strength of 3.0 MPa or more.