KR102775247B1 - Electrode material for electrode for saf using isotropic coke and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a method for manufacturing an electrode material using isotropic coke and to an electrode material manufactured thereby, wherein the aggregate satisfies the conditions of C: 95.00 to 99.00% in weight %, H: 0.01 to 0.05%, N: 0.5 to 1.2%, S: 0.15 to 0.50% in weight % in element analysis, and Ash (ash content): 0.2 to 0.5% in weight %, VM (volatile matter): 1 to 5%, Fixed Carbon (carbonization yield): 95 to 98% in industrial coal analysis, and wherein the aggregate satisfies the conditions of C: 90 to 95% in weight %, H: 2 to 6%, N: 1 to 4%, S: 0.2 to 1.0% in weight % in element analysis, and Ash (ash content): 0.10 to 0.40% in weight %, VM (volatile matter): 50 to 59.8%, Fixed Carbon (carbonization yield) in industrial coal analysis. A step of mixing pitch satisfying the conditions of 40 to 49.8% and softening point: 75 to 125℃; and a step of kneading.

Description

{ELECTRODE MATERIAL FOR ELECTRODE FOR SAF USING ISOTROPIC COKE AND MANUFACTURING METHOD THEREOF}

The present invention relates to a method for manufacturing an electrode material using isostatic coke and to an electrode material manufactured thereby, and more specifically, to an electrode material using isostatic coke as an aggregate which has higher mechanical properties and carbon content than electrode materials using existing calcined anthracite coal as an aggregate, and an electrode material suitable for a self-firing electrode for a SAF (Submerged Arc Furnace) which, when used as an electrode using the electrode material, has characteristics such as high mechanical strength, low electrical resistivity, high carbonization yield, and low ash content after self-firing.

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 the electrodes are mainly used to heat and melt the workpiece by the arc heat generated between the electrodes or between the electrode and the workpiece. Artificial graphite electrodes are mainly used in electric arc furnaces for steelmaking, but are also widely used in electric furnaces for manufacturing various products, such as non-ferrous metals, ferroalloys, and carbon disulfide.

Among them, Submerged Arc Furnaces (SAF) electric furnaces, which are widely used in alloy ferromagnetic manufacturing, produce raw materials by applying electricity to a graphite electrode to generate a large amount of thermal plasma heat. Meanwhile, unlike electrode rods for steelmaking, SAF electrodes are produced by inserting electrode material, melting the electrode material, filling it due to its own load, and baking it during use to play the role of an electrode rod. Because of this, self-baking and continuous operation are possible, it can be viewed as a self-baking continuous electrode type. There is a Soderberg type that is completely self-baking with a case made of sheet iron, and a semi-self-baking type that combines a case with segments of a baking electrode and fills the center with electrode material and connects them sequentially.

The present invention has been devised to improve existing electrode materials, and calcined anthracite, which is widely used as an aggregate in existing electrode materials, is a carbon material with a high ash content, including SiO ₂ , Al ₂ O ₃ , CaO, MgO, etc. When the ash content is high, the carbonization yield (fixed carbon) naturally decreases, which affects the properties of the electrode material or the properties of the electrode molded body after sintering. Therefore, the present invention provides a method for manufacturing a high-carbon electrode material with a low ash content and a high carbonization yield by replacing the existing aggregate, calcined anthracite, with isotropic coke, which is a high-strength, high-carbon material.

In order to achieve the above object, a method for manufacturing an electrode material according to one embodiment of the present invention comprises an aggregate satisfying the conditions of C: 95.00 to 99.00% in weight %, H: 0.01 to 0.05%, N: 0.5 to 1.2%, S: 0.15 to 0.50% in weight % in elemental analysis, and Ash (ash content): 0.2 to 0.5% in weight %, VM (volatile matter): 1 to 5%, Fixed Carbon (carbonization yield): 95 to 98% in weight % in industrial coal analysis, and C: 90 to 95% in weight %, H: 2 to 6%, N: 1 to 4%, S: 0.2 to 1.0% in weight % in industrial coal analysis, Ash (ash content): 0.10 to 0.40% in weight %, VM (volatile matter): 50 to 59.8%, Fixed Carbon (carbonization yield) A step of mixing pitch satisfying the conditions of 40 to 49.8%, softening point: 75 to 125℃; and a step of kneading.

In addition, in the method for manufacturing an electrode material according to one embodiment of the present invention, the particle size distribution of the aggregate may be, in wt%, over 11.2 mm: 5 to 10%, 11.2 mm to 1 mm: 35 to 70%, and less than 1 mm: 20 to 40%.

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

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

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

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

In addition, the molded body of the electrode material according to one 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 isostatic coke according to the present invention and the manufacturing method thereof, compared to the electrode material using existing calcined anthracite coal as aggregate, the ash content is reduced by 85 to 90%, the VM (volatile matter) content is reduced by 30 to 40%, the fixed carbon (carbonization yield) is increased by 5 to 10%, the electrical resistivity is reduced by 10 to 20%, the compressive strength is increased by 0 to 10%, and the bending strength is increased by 10 to 40%, so that a high-quality electrode material having high carbon content and improved physical properties compared to existing products can be provided.

Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention may be modified in various other forms, and the technical idea of the present invention is not limited to the embodiments described below. In addition, the embodiments of the present invention are provided in order to more completely explain the present invention to a person having average knowledge in the relevant technical field.

The terminology used in this application is 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, it should be noted that the terms "comprise" or "have" used in this application are used to clearly indicate the presence of a feature, step, function, component, or combination thereof described in the specification, and are not used to preliminarily exclude the presence of other features, steps, functions, components, or combinations thereof.

Meanwhile, unless otherwise defined, all terms used in this specification should be considered to have the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention belongs. Accordingly, unless explicitly defined in this specification, specific terms should not be interpreted in an overly idealistic or formal sense. For example, singular expressions in this specification include plural expressions unless the context clearly indicates an exception.

In addition, the terms "about", "substantially", etc. in this specification are used in the sense that they are at or close to the numerical values when manufacturing and material tolerances inherent in the meanings mentioned are presented, and are used to prevent unscrupulous infringers from unfairly using the disclosure contents in which exact or absolute numerical values are mentioned to help understanding of the present invention. The embodiments described in this specification and the configurations illustrated in the drawings are preferred examples of the disclosed invention, and there may be various modified examples that can replace the embodiments and drawings of this specification at the time of filing of the present application.

In addition, the terminology used in this specification is used for the purpose of describing embodiments, and is not intended to limit and/or restrict the disclosed invention. In addition, each step may be performed in a different order than stated, unless the context clearly indicates a specific order.

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

According to one embodiment of the present invention, a method for manufacturing an electrode material comprises aggregates that satisfy the conditions of C: 95.00 to 99.00% in weight %, H: 0.01 to 0.05%, N: 0.5 to 1.2%, S: 0.15 to 0.50% in weight %, and Ash (ash content): 0.2 to 0.5%, VM (volatile matter): 1 to 5%, and Fixed Carbon (carbonization yield): 95 to 98% in weight % upon elemental analysis, and C: 90 to 95% in weight %, H: 2 to 6%, N: 1 to 4%, S: 0.2 to 1.0% in weight %, and Ash (ash content): 0.10 to 0.40%, VM (volatile matter): 50 to 59.8%, and Fixed Carbon (carbonization yield): 40 to 49.8% in weight % upon elemental analysis. Softening point: a step of mixing pitch that satisfies the condition of 75 to 125℃; and

Includes a mixing step;

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

In addition, in the method for manufacturing an electrode material according to one embodiment of the present invention, the particle size distribution of the aggregate may be, in wt%, over 11.2 mm: 5 to 10%, 11.2 mm to 1 mm: 35 to 70%, and less than 1 mm: 20 to 40%. The particle size distribution of the aggregate is an important factor that determines the strength of a later molded body, and fine particles of 1 mm or less are a factor that can secure bonding with the pitch and fluidity.

In addition, in the method for manufacturing an electrode material according to one embodiment of the present invention, the pitch mixed in the mixing step may be 20 to 30% by weight. In addition, in the method for manufacturing an electrode material according to one embodiment of the present invention, the mixing step may be a step of modifying by mixing at a temperature of 200 to 400° C. for 3 to 6 hours. After mixing, the material is put into a mold, shaped into a certain size, and then hardened to manufacture.

As described above, after mixing the aggregate and pitch, the briquette molded body is manufactured by evenly mixing and reforming the mixture of the aggregate and pitch through the kneading process. In the electric furnace of the self-firing method, the electrode material is put in, and it is filled and fired by the heat and its own load, and it acts as an electrode rod. At this time, plasticity, which is one of the factors to be considered in the process of filling and firing, is a very important factor. If the plasticity is good, it softens well, but due to high fluidity, it may not be properly fired during electrode formation and may spill down, and if the plasticity is bad, it may not be filled sufficiently and pores may remain, causing a deterioration in the properties of the electrode molded body after firing. Therefore, in order to manufacture a briquette molded body with optimal plasticity, appropriate reforming of the mixture 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 satisfy 10~20% to satisfy the optimal conditions for manufacturing the electrode molded body. The mixing temperature and time conditions are important factors affecting plasticity. If the temperature is lower than or the mixing time is shorter than the temperature described in the manufacturing method of the present invention, the pitch is not reformed, so the plasticity becomes too high, and the shape cannot be formed and molding is not possible. In addition, if the temperature is high or the mixing time is too long, the rapid solidification causes pores to be created, which adversely affects the physical properties such as a decrease in density, an increase in electrical resistance, and a decrease in strength.

In addition, the temperature and time of mixing should be such that the mixture (electrode material) with low pitch and aggregate having a softening point of 75 to 125°C is formed to form an appropriate softening point, thereby preventing the electrode from flowing out and being lost when passing through the molten phase during the manufacture of the electrode if the softening point is too low, and preventing the problem of pores being formed due to insufficient filling if the softening point is too high, which adversely affects the properties of the electrode after firing.

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

In addition, 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 the pores that may adversely affect the electrical and mechanical properties may be reduced.

In addition, 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 may exhibit electrical characteristics suitable for use as an electrode by satisfying the electrical resistivity within the above range.

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 can withstand various stresses such as gravity from top to bottom and the load of the electrode itself when used as an electrode by satisfying the strength within the above range.

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 the rights of the present invention is determined by the matters described in the patent claims and matters reasonably inferred therefrom.

[Example]

In weight%, the particle size distribution of aggregate (isostatic coke) is, in weight%, over 11.2 mm: 5 to 10%, 11.2 mm to 1 mm: 35 to 70%, and less than 1 mm: 20 to 40%, the pitch is 20 to 30% in weight%, and the raw material mixed using pitch having a softening point of 75 to 125°C was kneaded at a temperature of 200 to 400°C for 3 to 6 hours, and the elemental analysis and industrial coal analysis of the isostatic coke used are shown in Table 1 below.

division Elemental Analysis (Wt%) Industrial coal analysis (weight%) C H N S ASH VM FC
(Fixed Carbon) Inventor 1 Isotropic coke 1 98.28 0.02 0.77 0.33 0.44 2.38 97.13 Inventor 2 Isostatic coke 2 98.58 0.00 0.55 0.37 0.41 2.30 97.24 Comparative material 1 coke byproduct1 95.94 0.03 0.66 0.36 0.38 1.95 97.62 Comparative material 2 Coke byproduct 2 91.43 1.91 1.16 0.38 4.23 6.74 88.7 Comparative material 3 Calcined anthracite coal 96.39 0.23 0.44 0.32 4.26 4.08 91.41

Table 1 shows the results of element analysis and industrial coal analysis of isotropic coke used as aggregate of electrode material. It can be confirmed that isotropic coke suitable as aggregate of the present invention satisfies all the scope of the present invention and satisfies high carbonization yield. The particle size distribution of such isotropic coke was mixed as follows in weight %: over 11.2 mm: 5-10%, 11.2 mm~1 mm: 35-70%, and less than 1 mm: 20-40%, and used as aggregate.

division Ash
% VM
% Fixed Carbon
% Softening point
℃ Invention Binder 1 Peach 1 0.26 56.76 41.70 90 Invention Binder 2 Peach 2 0.21 56.92 42.18 90 Comparison Binder 1 Peach 3 0.04 56.06 43.90 120 Comparison Binder 2 Peach 4 0.56 45.97 53.53 120

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

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

The above Table 3 shows the properties of electrode materials (before sintering) according to the mixing conditions. When the mixing temperature and mixing time conditions of the present invention are satisfied, they are marked as O, and when they are not satisfied, they are marked as ×. When the mixing temperature is too low, the plasticity is measured too high, and when the mixing time is too short, the plasticity is also measured high. Accordingly, inventive examples 1 and 2 in which both the mixing temperature and the training time satisfy the range of the present invention, both the softening point and the plasticity satisfy the range of the present invention, but it was confirmed that in comparative examples 1 to 6 that do not satisfy the mixing temperature or the mixing time, the plasticity exceeded 20%. When producing the electrode material, the mixing was performed using the same overhead stirrer and heating mantle, and after each mixing process, the electrode material was put into a cylindrical mold with a diameter of 40 mm to produce a plasticity specimen. When measuring the plasticity, the measurement was performed four times and the average value was used, which is shown in Table 4 below.

division aggregate bookbinder Mixing temperature Mixing time Molded body of electrode material apparent density
(g/cm ³⁾ Electrical resistivity
(μΩm) Compressive strength
(MPa) Bending strength
(MPa) Invention Example 1 Isotropic coke 1 Peach 1 O O 1.255 90.65 6.89 3.62 Invention example 2 Isostatic coke 2 Peach 2 O O 1.250 99.00 5.54 3.59 Comparative Example 1 Isotropic coke 1 Peach 1 X X 1.310 287.83 1.20 2.43 Comparative Example 7 Haso smokeless coal Peach 1 O O 1.210 109.31 6.86 2.74 Comparative Example 8 Haso smokeless coal Peach 1 X X 1.330 240.23 1.40 0.69

The sintering of the electrode material was done by using a briquette molding machine after the mixing process of the electrode material to make oval briquettes with a diameter of 4 cm, and then putting them in a 120Φ stainless steel cylindrical mold and sintering them. The sintering conditions were 1,000℃ per minute (heating 2℃/min, holding for 1 hour, N ₂ atmosphere). The physical properties after firing were measured according to the standard of KS L 3409 (Test method for physical properties of graphite materials), and the average value was used by measuring five samples for each condition, and is shown in Table 4 above. That is, it was confirmed that the molded body manufactured by mixing the isotropic coke and pitch according to the present invention and firing the electrode material manufactured under the mixing 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, a compressive strength of 5.0 MPa or more, a bending strength of 3.0 MPa or more, and a plasticity of 10 to 20%. On the other hand, it was confirmed that the physical properties of the electrode material molded body did not satisfy the range of the present invention when the aggregate was calcined anthracite coal or when the mixing conditions were not suitable.

Although exemplary embodiments of the present invention have been described above, the present invention is not limited thereto, and those skilled in the art will understand that various changes and modifications are possible within the scope of the claims set forth below.

Claims (9)

In the case of elemental analysis, the aggregate satisfies the conditions of C: 98.25~99.00% in weight%, H: 0.01~0.05%, N: 0.5~1.2%, S: 0.15~0.50%, in the case of industrial coal analysis, Ash (ash content): 0.2~0.5% in weight%, VM (volatile matter): 1.5~4.8%, Fixed Carbon (carbonization yield): 95~98%, and in the case of elemental analysis, C: 90~95% in weight%, H: 2~6%, N: 1~4%, S: 0.2~1.0%, in the case of industrial coal analysis, Ash (ash content): 0.10~0.40%, VM (volatile matter): 50~59.8%, Fixed Carbon (carbonization yield): 40~49.8%, softening point: A step of mixing pitch that satisfies the conditions of 75~125℃; and
The mixing stage;
A method for manufacturing an electrode material, characterized by including a. In claim 1,
A method for manufacturing an electrode material, characterized in that the particle size distribution of the aggregate is, in weight %, over 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 manufacturing an electrode material, characterized in that the pitch mixed in the mixing step is 20 to 30% by weight. In claim 1,
A method for manufacturing an electrode material, characterized in that the above mixing step is a step of reforming by mixing at a temperature of 200 to 400°C for 3 to 6 hours. An electrode material manufactured by the manufacturing method of claim 1, characterized in that the electrode material has a plasticity of 10 to 20%. A molded body of an electrode material, characterized in that the electrode material of claim 5 is sintered and has a density of 1.25 to 1.30 g/cm ³ . A molded body of an electrode material, characterized in that the electrode material of claim 5 is sintered and has an electrical resistivity of 70 to 100 μΩm. A molded body of an electrode material, characterized in that the electrode material of claim 5 is sintered and has a compressive strength of 5.0 MPa or more. A molded body of an electrode material, characterized in that the electrode material of claim 5 is sintered and has a bending strength of 3.0 MPa or more.