KR20250038388A - Composition for self baking electrode, briquet, manufacturing method for electrode part and electrode part - Google Patents

Abstract

An embodiment of the present invention provides a composition for a self-igniting electrode that can be used in an electric furnace, comprising a carbonaceous material containing carbon and coal tar pitch, wherein the coal tar pitch has an a-axis crystallite length (L _a ) of 40 nm to 80 nm, as measured by X-ray diffraction analysis of graphite formed when carbonized, and a ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) (L _a /L _c ) of 2 to 3.
Therefore, according to the embodiments of the present invention, briquettes having low electrical resistivity and high electrical conductivity can be manufactured even if the coal tar pitch content is small. Accordingly, the amount of coal tar pitch used and the cost due to the coal tar pitch liquefaction process can be reduced.

Description

Composition for self baking electrode, briquette, manufacturing method for electrode part and electrode part

The present invention relates to a composition for a self-igniting electrode, a briquette, a method for manufacturing an electrode part, and an electrode part, and more particularly, to a composition for a self-igniting electrode, a briquette, a method for manufacturing an electrode part, and an electrode part capable of manufacturing a self-igniting electrode having low electrical resistivity.

An electric furnace is a device that melts iron raw materials such as reduced iron or scrap by applying electricity to the electrode section and utilizing the heat and arc generated from the electrode section. In addition, there is an electric furnace that uses a self-firing electrode as the electrode section. A self-firing electrode is an electrode that is prepared by inserting briquettes into a cylindrical case installed to be inserted into the electric furnace and melting and sintering the briquettes using the heat inside the electric furnace and the electricity applied to the case. The briquettes are manufactured by molding a composition mixed with anthracite coal and a binder, and coal tar pitch is used as the binder.

The self-igniting electrode generates heat and arc by the applied electric power. Therefore, the self-igniting electrode must have low electrical resistance so that it can generate the desired heat and arc even with a small electric power. In addition, in order to secure the electrical characteristics of the self-igniting electrode, the electrical resistance of the briquette must be low.

To this end, a large amount of coal tar pitch is included when mixing anthracite coal and coal tar pitch. That is, a large amount of coal tar pitch is mixed in order to improve the bonding strength between anthracite coal particles and increase the density of the briquette. However, there is a problem that the cost increases due to the increased use of coal tar pitch.

In addition, before mixing anthracite coal and coal tar pitch, the coal tar pitch is liquefied. However, as the amount of coal tar pitch used increases, the amount of coal tar pitch to be liquefied increases, which causes a problem in that the time and cost consumed for liquefaction increase.

Japanese Publication Patent JP 2007-537565

The present invention provides a composition for a self-igniting electrode, a briquette, a method for manufacturing an electrode part, and an electrode part capable of manufacturing a self-igniting electrode having low electrical resistivity.

The present invention provides a composition for a self-igniting electrode, a briquette, a method for manufacturing an electrode part, and an electrode part capable of lowering electrical resistivity and improving electrical conductivity while reducing the content of coal tar pitch.

The present invention provides a composition for a self-igniting electrode, a briquette, a method for manufacturing an electrode portion, and an electrode portion capable of reducing manufacturing costs.

An embodiment of the present invention provides a composition for a self-igniting electrode that can be used in an electric furnace, comprising a carbonaceous material containing carbon and coal tar pitch, wherein the coal tar pitch has an a-axis crystallite length (L _a ) of 40 nm to 80 nm as measured by X-ray diffraction analysis of graphite formed when carbonized, and a ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) (L _a /L _c ) can be 2 to 3.

The content of the coal tar pitch may be 20 to 40 parts by weight for 100 parts by weight of the carbonaceous material.

The above-mentioned coal tar pitch may have a carbonization rate of 35% to 50% when carbonized.

The ash content among 100 wt% of the above carbonaceous material may be 0 wt% or more and 5 wt% or less.

The content of volatile matter among 100 wt% of the above carbonaceous material may be 0 wt% or more and 3 wt% or less.

The above carbonaceous material may include at least one of anthracite coal and coke.

The above coke may include at least one of needle coke and pitch coke.

At least one of the above bed coke and pitch coke may be at least one of coal-based coke and petroleum-based coke.

Briquettes are manufactured by molding the composition for the above-mentioned self-igniting electrode.

The briquette may have an electrical resistivity of more than 0 μΩm and less than or equal to 120 μΩm, and the briquette may have a spreadability, which is a ratio of an increase in the diameter (D ₂ ) of the briquette after heating to the diameter (D ₁ ) of the briquette before heating, of 10% to 35%.

A method for manufacturing an electrode part according to an embodiment of the present invention may include: a process for preparing a carbonaceous material; a process for preparing coal tar pitch, wherein the a-axis crystallite length (L _a ) measured by X-ray diffraction analysis of graphite formed when carbonized is 40 nm to 80 nm and the ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) (L _a /L _c ) can be 2 to 3; a process for manufacturing a briquette including the prepared carbonaceous material and coal tar pitch; a process for introducing the briquette into the interior of a case of the electrode part installed to be inserted into a main body of an electric furnace; and a process for applying electric power to the case to melt and sinter the briquette, thereby forming a self-extinguishing electrode capable of protruding out of the case.

The above-mentioned prepared coal tar pitch is solid, and before manufacturing the briquette, a process of heating the prepared carbonaceous material and a process of heating the prepared solid coal tar pitch to a temperature higher than its softening point to liquefy it, and the process of manufacturing the briquette may include a process of mixing the heated carbonaceous material and the liquefied coal tar pitch; and a process of forming a mixture in which the carbonaceous material and the coal tar pitch are mixed.

When heating the prepared carbonaceous material, the carbonaceous material can be heated so that the temperature of the carbonaceous material becomes higher than the softening point of the coal tar pitch.

In heating the carbonaceous material so that the temperature thereof is higher than the softening point of the coal tar pitch, the carbonaceous material may be heated so that the temperature thereof is 10°C to 30°C higher than the softening point of the coal tar pitch.

In preparing the above carbonaceous material, a carbonaceous material can be prepared in which the ash content is 0 wt% or more and 5 wt% or less among 100 wt% of the carbonaceous material, and the volatile matter content is 0 wt% or more and 3 wt% or less.

In mixing the above carbonaceous material and the liquefied coal tar pitch, the carbonaceous material and the liquefied coal tar pitch can be mixed while heating them at a temperature higher than the softening point of the coal tar pitch.

An embodiment of the present invention may include a case having an internal space formed to extend in one direction as an electrode part, a portion of which is installed to be inserted into a main body of an electric furnace; and a self-firing electrode formed by firing the briquette described in claim 9, a portion of which is positioned inside the case and the remainder of which is formed to protrude outside the lower side of the case.

According to embodiments of the present invention, briquettes having low electrical resistivity and high electrical conductivity can be manufactured even with a small content of coal tar pitch. Accordingly, the amount of coal tar pitch used and the cost due to the liquefaction process of coal tar pitch can be reduced.

In addition, the electrical resistivity of the self-igniting electrode manufactured using briquettes can be reduced and the electrical conductivity can be improved. Therefore, in manufacturing molten metal by melting raw materials with heat and arc generated by applying electric power to the self-igniting electrode, the efficiency of heat and arc generated in the self-igniting electrode by the applied electric power can be increased.

FIG. 1 is a schematic drawing of an electric furnace having an electrode section according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view illustrating a state in which an electrode part according to an embodiment of the present invention is installed to be inserted into the main body of an electric furnace.
FIG. 3 is a flowchart illustrating a method for manufacturing briquettes according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the attached drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and these embodiments are provided only to ensure that the disclosure of the present invention is complete, and to fully inform a person having ordinary skill in the art of the scope of the invention. In order to explain the embodiments of the present invention, the drawings may be exaggerated, and the same reference numerals in the drawings represent the same components.

FIG. 1 is a schematic drawing of an electric furnace having an electrode section according to an embodiment of the present invention.

An electric smelting furnace apparatus is a device that melts raw material (M) introduced into it to produce a molten material, that is, molten metal (L). Referring to FIG. 1, the electric furnace may include a main body (100) having an internal space capable of processing raw material (M), an electrode part (200) at least partially installed to be positioned inside the main body (100) so as to generate heat for melting the raw material (M), and a power supply part (300) connected to the electrode part (200) so as to be able to apply power. In addition, the electric furnace may include a raw material supply part (400) connected to the main body (100) so as to be able to introduce raw material (M).

The raw material (M) introduced into the internal space of the main body (100) may include a first raw material (M1) and a second raw material (M2). The first raw material (M1) may include, for example, reduced iron, and as a more specific example, the first raw material (M1) may include direct reduced iron (DRI). The second raw material (M2) may include a reducing agent, and as a more specific example, the second raw material (M2) may include coke. Inside the main body (100), the first raw material (M1) and the second raw material (M2) are melted by the heat generated from the electrode part (200), and the first raw material (M1) is reduced by the second raw material (M2), thereby producing a molten metal (L).

The direct reduced iron may be at least one of low-grade direct reduced iron manufactured using ore having an iron (Fe) content of less than 65 wt% before reduction and high-grade direct reduced iron manufactured using ore having an iron (Fe) content of 65 wt% or more before reduction. In addition, the first raw material (M1) direct reduced iron (DRI) may be direct reduced iron reduced using hydrogen, that is, 'hydrogen direct reduced iron'. Accordingly, an electric furnace for melting and reducing the first raw material (M1) hydrogen direct reduced iron to manufacture molten metal may be named an 'electric furnace for melting hydrogen-reduced direct reduced iron'.

In the above, it was explained that the first raw material (M1) fed into the electric furnace includes hydrogen-directly reduced iron. However, the first raw material (M1) may include direct reduced iron manufactured by reduction using various methods in addition to direct reduced iron reduced using hydrogen.

In addition, the first raw material (M1) is not limited to direct reduced iron, and may include scrap having a higher iron (Fe) content than the direct reduced iron. The scrap may be iron scrap having an iron (Fe) content exceeding 70 wt%, more preferably iron scrap having an iron (Fe) content of 85 wt% to 99 wt%.

The main body (100) may include a body (110) having an internal space and a cover (120) covering an opening provided on the upper side of the body (110).

The furnace body (110) may be a barrel-shaped body with an inner space and an open upper side. The furnace body (110) may include an outer wall body (110a) made of iron or metal and an inner wall body (110b) constructed of a refractory material to surround the inner wall of the outer wall body (110a).

The furnace body (110) may be provided with a first discharge port (111) for discharging molten metal (L) and a second discharge port (112) for discharging slag (S) floating on top of the molten metal (L). Each of the first and second discharge ports (112) may be provided on a side wall of the furnace body (110) or on a lower floor of the furnace body (110). Taking Fig. 1 as an example, the first discharge port (111) may be provided on one side wall of the furnace body (110), and the second discharge port (112) may be provided on the other side wall of the furnace body (110). Of course, the first and second discharge ports (111, 112) are not limited to the above-described positions and may be provided at various positions that can discharge the molten metal (L) and the slag (S) to the outside.

Outside the furnace body (110), containers (10a, 10b) capable of accommodating molten metal (L) and slag (S), respectively, may be arranged. That is, a first container (10a) may be arranged below a first discharge port (111) on the outside of the furnace body (110), and a second container (10b) may be arranged below a second discharge port (112). Here, the first container (10a) that accommodates the molten metal (L) discharged from the first discharge port (111) may be, for example, a ladle, and the second container (10b) that accommodates the slag (S) discharged from the second discharge port (112) may be a slag pot.

The cover (120) is installed on the upper part of the body (110) so as to close the upper opening of the body (110). At this time, the cover (120) may be made of a refractory material. In addition, the cover (120) may be provided with a hole through which a part of the electrode part (200) may pass and a hole through which a part of the raw material supply part (400) may pass. In addition, the cover (120) may further be provided with an inlet through which the raw material (M) may be introduced.

The raw material supply unit (400) is a means for supplying raw material (M) to the main body (100) of the electric furnace. This raw material supply unit (400) may include, for example, a first hopper (410) in which a first raw material (M1) is stored, a second hopper (420) in which a second raw material (M2) is stored, and a feeder (430) connected to the first and second hoppers (410, 420) so that the first and second raw materials (M1, M2) can be fed into the interior of the main body (100).

The feeder (430) may include, for example, a first transfer pipe (431) connected to the first hopper (410), a second transfer pipe (432) connected to the second hopper (420), and a third transfer pipe (433) installed through the cover (120) so that one end is connected to the first and second transfer pipes (431, 432) and the other end is positioned in the internal space of the main body (100). In addition, a valve may be installed in at least one of the first transfer pipe (431), the second transfer pipe (432), and the third transfer pipe (433).

In the above, it has been described that the raw material supply unit (400) includes first and second hoppers (410, 420). However, it is not limited thereto, and a hopper in which raw materials other than the first and second raw materials (M1, M2) are stored may be additionally provided.

In addition, the raw material (M) is not limited to being fed using the raw material supply unit (400) as described above, and may also be fed into the interior of the main body (100) through the feeding port provided in the cover (120).

FIG. 2 is a cross-sectional view illustrating a state in which an electrode part according to an embodiment of the present invention is installed to be inserted into the main body of an electric furnace.

The electrode part (200) generates heat and an arc by the applied power and supplies heat to the interior of the main body part (100). Here, the power may mean voltage or current, and the heat generated in the electrode part (200) may include resistive heat due to the applied power. In addition, the heat and arc supplied to the interior of the main body part (100) by the electrode part (200) melt or dissolve the raw material (M), and thus a molten material, i.e., molten metal, is produced.

The electrode unit (200) may be provided in multiple pieces, and for example, as shown in Fig. 1, three electrode units (200a, 200b, 200c) may be provided. In addition, the multiple electrode units (200a, 200b, 200c) may be connected to one power supply unit (300).

In the above, it has been described that a plurality of electrode parts (200a, 200b, 200c) are connected to a single power supply part (300). However, the present invention is not limited thereto, and a plurality of power supply parts (300) may be provided so that they can be connected one-to-one with a plurality of electrode parts (200a, 200b, 200c). In addition, the number of electrode parts is not limited to the above-described example, and may be provided as one or as three or more.

Hereinafter, the configuration of the electrode part (200) will be described. At this time, a plurality of electrode parts (200a, 200b, 200c) are provided with the same configuration and shape. Here, one electrode part will be described as an example, and for the convenience of explanation, the drawing symbol of the electrode part will be referred to as '200'.

Referring to FIG. 2, the electrode unit (200) may include a case (210) having an internal space, a self-igniting electrode (220) formed so that a portion thereof is inserted into the case (210) and the remainder thereof protrudes outside the case (210) so as to generate heat by electric power, and a power supply member (230) mounted on the case (210) so as to supply electric power to the case (210). In addition, the electrode unit (200) may include a lifter (not shown) connected to the case (210) so as to lower or raise the case (210).

The electrode part (200) is installed so that a part is located inside the main body part (100) and the rest is located outside the main body part (100), as illustrated in FIG. 1. That is, the electrode part (200) can be installed so that a part penetrates the cover (120) in the vertical direction and is located inside the furnace body (110). Accordingly, a part of the electrode part (200) is located on the lower side of the cover (120) and accommodated inside the furnace body (110), and another part protrudes above the cover (120) and is located outside the furnace body (110). In addition, the height of the electrode part (200) is adjusted so that the lower part thereof is immersed in the slag (S) floating on top of the molten metal or buried in the raw material (M) piled on top of the slag (S).

The case (210) may be a tubular shape having an internal space. That is, the case (210) may have an internal space extending in the vertical direction and may be a tube shape with the upper and lower sides open. The shape of the case (210) is not particularly limited, but may be, for example, a cylindrical shape whose cross-section is circular. In addition, the case (210) may be made of metal.

As described above, the electrode part (200) is installed so that a part is located inside the body (110) and the rest is located outside the body (110). To this end, the case (210) is installed so that a part is located inside the body (110) and the rest is located outside the body (110) by penetrating the cover (120) in the vertical direction.

The power supply member (230) is a means for transmitting power transmitted from the power supply unit (300) to the case (210). The power supply member (230) may be installed in the case (210) so as to be located outside the main body (100), that is, on the upper side of the cover (120), as shown in FIG. 2. The material of the power supply member (230) is not particularly limited as long as it is a conductor capable of transmitting power, but may be prepared using, for example, a material including copper (Cu).

In addition, a power supply line (310) may be connected between the power supply unit (300) and the power supply member (230). Accordingly, power output from the power supply unit (300) may be transmitted to the power supply member (230) via the power supply line (310). In addition, power transmitted to the power supply member (230) may be transmitted to the case (210) and then to the self-storing electrode (220).

The self-sparking electrode (220) is connected to the case (210) so that a portion thereof can protrude outside the lower side of the case (210), as shown in FIG. 2. That is, the self-sparking electrode (220) is connected so that a portion thereof is located inside the case (210) and the remainder thereof protrudes outside the case (210). This self-sparking electrode (220) is made of a material including carbon (C), and generates resistive heat when power is applied. In addition, an arc may be generated around the self-sparking electrode (220) at this time.

The self-firing electrode (220) is an electrode formed by introducing a material containing carbon into the interior of the case (210) and self-firing or self-baking the material by heat generated in the case (210). Here, the material introduced into the interior of the case (210) may be a briquette (B). In addition, when the briquette (B) is sintered, it may be graphitized, and thus the self-firing electrode (220) may be an electrode including graphite or a graphite electrode.

In addition, the self-igniting electrode (220) may be formed in the shape of a rod as illustrated in FIG. 2, and its lower part may protrude toward the lower side of the case (210). At this time, the self-igniting electrode (220) is not connected to the case (210) in a state in which it is manufactured in the shape of a rod, but is prepared by introducing a briquette (B) into the interior of the case (210) as described above and firing the introduced briquette (B).

The shape of the self-emitting electrode (220) is not limited to the rod shape described above, and may be changed in various ways depending on the shape of the case (210).

When the electric power transmitted to the case (210) is transmitted to the self-extinguishing electrode (220) during the operation of the electric furnace, heat is generated in the self-extinguishing electrode (220) and an arc is generated around the self-extinguishing electrode (220). Accordingly, the first and second raw materials (M1, M2) inside the main body (100) are melted, and a molten metal (L) is produced. As the heat and arc are generated in the self-extinguishing electrode (220), the lower part of the self-extinguishing electrode (220) protruding toward the lower side of the case (210) is consumed, and thus at least one of the length and diameter of the self-extinguishing electrode (220) is reduced. In addition, the self-extinguishing electrode (220) may be oxidized and consumed by air introduced into the main body (100) and by oxidizable metal generated inside the main body (100). In this way, the self-consumable electrode (220) is a consumable electrode in which at least one of the length and diameter is reduced by an arc, heat, and oxidation reaction.

Therefore, to enable the self-igniting electrode (220) to be formed continuously or continuously while operating the electric furnace, briquettes (B) for forming the self-igniting electrode (220) are introduced into the case (210). The introduced briquettes (B) undergo softening, melting, and sintering reactions inside the case (210) to become solid self-igniting electrodes (220).

Since the self-igniting electrode (220) generates heat and arc by the applied power, the self-igniting electrode (220) needs to have low electrical resistivity and high electrical conductivity. That is, the self-igniting electrode (220) needs to have low electrical resistivity and high electrical conductivity so that the power applied to the self-igniting electrode (220) to generate heat and arc of a desired size can be reduced. That is, the power consumption that needs to be applied to the self-igniting electrode (220) to melt the raw material (M) inside the main body (100) can be reduced.

In addition, the electrical resistivity and electrical conductivity of the self-sparking electrode (220) need to be uniform. More specifically, if the electrical resistivity or electrical conductivity of the self-sparking electrode (220) is not uniform and differs depending on the location, the heat and arc generated from the self-sparking electrode (220) differ depending on the location. In this case, the raw material accommodated inside the main body (100) may not be heated uniformly. That is, some of the raw materials (M) accommodated inside the main body (100) may melt, but others may not melt. Therefore, the electrical resistivity and electrical conductivity of the self-sparking electrode (220) need to be uniform.

A briquette (B) according to an embodiment is manufactured by molding a composition including a material containing carbon (C) (hereinafter, “carbonaceous material”) and coal tar pitch.

The carbonaceous material may include at least one of anthracite coal and coke. And the coke may be at least one of needle coke and pitch coke. In addition, the coke may be at least one of coal-based coke obtained from coal and petroleum-based coke obtained from petroleum. That is, at least one of the needle coke and the pitch coke used as the carbonaceous material may be at least one of the coal-based coke and the petroleum-based coke.

In addition, a carbonaceous material having an ash content of 5 wt% or less (0 wt% or more) among 100 wt% of the carbonaceous material is used. In addition, it is preferable that the carbonaceous material have a volatile matter content of 3 wt% or less (0 wt% or more) among 100 wt% of the carbonaceous material. To this end, when the carbonaceous material is prepared, it is heated to 800°C or higher to vaporize the volatile matter contained in the carbonaceous material so that the volatile matter becomes 3 wt% or less.

The coal tar pitch used in the manufacture of the briquette (B) or included in the briquette (B) is a coal tar pitch having an a-axis crystallite length (L _a ) of 40 nm to 80 nm, as measured by X-ray diffraction analysis of graphite formed when carbonized, and a ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) (L _a /L _c ) of 2 to 3. Here, each of the a-axis crystallite length (L _a ) and the c-axis crystallite length (L _c ) is with respect to graphite.

Of course, the ratio of the a-axis crystallite length (L _a ) of graphite to the c-axis crystallite length (L _c ) of graphite (L _a /L _c ) can be variously changed in the range of 2 to 3, and the a-axis crystallite length (L _a ) of graphite can be variously changed in the range of 40 nm to 80 nm. That is, the ratio of the a-axis crystallite length (L _a ) of graphite to the c-axis crystallite length (L _c ) of graphite (L _a /L _c ) can be 2.3 to 2.7 (2.3 or more and 2.7 or less), 2 or more and less than 2.3, or more than 2.7 and 3 or less. In addition, the a-axis crystallite length (L _a ) of graphite can be 50 nm to 70 nm (50 nm or more and 70 nm or less), 40 nm or more and less than 50 nm, or more than 70 nm and 80 nm or less.

In addition, the coal tar pitch used in the manufacture of briquettes (B) is a coal tar pitch which, when carbonized, can have a carbonization rate (or carbonization yield) of 35% to 50%. At this time, the carbonization rate of the coal tar pitch can be variously changed within the range of 35% to 50%. That is, the carbonization rate of the coal tar pitch can be 40% to 45% (40% or more and 45% or less), 35% or more and less than 40%, or more than 45% and 50% or less.

And, the coal tar pitch used in the manufacture of briquettes (B) is a coal tar pitch whose interplanar spacing d(002) measured by X-ray diffraction analysis after carbonization can be 0.3354 nm to 0.3364 nm.

In addition, the coal tar pitch used in the production of briquettes (B) has a softening point of 80°C to 120°C. The softening point of the coal tar pitch can be varied within a range of 80°C to 120°C. That is, the softening point of the coal tar pitch can be 90°C to 110°C (90°C or more and 110°C or less), 80°C or more and less than 90°C, or more than 110°C and 120°C or less.

The coal tar pitch used in the manufacture of the briquette (B) is not a carbonized coal tar pitch. That is, when the briquette (B) is charged into the case (210) of the electrode part (200) and the briquette (B) is heated by the heat generated by applying electricity to the case (210), the coal tar pitch contained in the briquette (B) is carbonized.

In the embodiment, when manufacturing a briquette (B), uncarbonized coal tar pitch is used. And, when manufacturing a briquette (B) using uncarbonized coal tar pitch, the briquette (B) is manufactured using coal tar pitch that can satisfy the above-described conditions when carbonized. More specifically, when coal tar pitch is heated to a predetermined temperature or higher, it is carbonized, thereby generating graphite. And, when X-ray diffraction analysis is performed on the graphite, the a-axis crystallite length (L _a ) and the c-axis crystallite length (L _c ) of the graphite can be measured. In the embodiment, it is conditional that the a-axis crystallite length (L _a ) of the graphite is 40 nm to 80 nm, and the ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) (L _a /L _c ) is 2 to 3. That is, among various types of coal tar pitches, a coal tar pitch is used to manufacture briquettes ( _B ) in _which the a-axis crystallite length (L _a ) of graphite formed when carbonized is 40 nm to 80 nm and the ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) can be 2 to 3.

In addition, it may be more effective to use coal tar pitch whose carbonization rate (or carbonization yield) can be 35% to 50% when carbonized. And, it may be more effective to use coal tar pitch whose interplanar spacing d(002) measured by X-ray diffraction analysis after carbonization can be 0.3354 nm to 0.3364 nm.

Coal tar pitch acts as a binder (bonding material or joining material). The composition or briquette (B) for a self-igniting electrode contains a carbonaceous material and the coal tar pitch as described above. At this time, it is effective that the coal tar pitch is contained in an amount of 20 to 40 parts by weight with respect to 100 parts by weight of the carbonaceous material. The content of the coal tar pitch can be variously changed in the range of 20 to 40 parts by weight with respect to 100 parts by weight of the carbonaceous material. That is, the content of the coal tar pitch can be 25 to 35 parts by weight (25 to 35 parts by weight) with respect to 100 parts by weight of the carbonaceous material, or 20 to 25 parts by weight, or more than 35 to 40 parts by weight.

The briquette (B) is manufactured by molding or assembling a composition for a self-igniting electrode, which is a mixture containing a carbonaceous material and coal tar pitch. The manufactured briquette (B) has low electrical resistivity and appropriate spreadability. For example, the electrical resistivity of the briquette (B) may be 120 μΩm or less, and the spreadability may be 10% to 35%. At this time, it may be more effective when the electrical resistivity of the briquette (B) is 100 μΩm or less, and it may be more effective when the spreadability is 15% to 25%. The meaning of spreadability will be specifically explained later.

When the briquette (B) is introduced into the case (210) and heated, a solid electrode (220) is manufactured through a softening, melting, and firing process. That is, when power is supplied to the case (210) through the power supply unit (300) and the power supply member (230), the power is transmitted to the briquette (B) introduced into the case (210). Accordingly, resistive heat is generated in the briquette (B), and the briquette (B) is softened. Then, the softened briquette (B) is melted or melted by the resistive heat generated by the continuously supplied power, and is then manufactured into a solid electrode (220) through a firing reaction, and the electrode manufactured in this way is called a self-firing electrode.

The area inside the main body (100) of the case (210) may melt and disappear over time due to its high temperature. That is, the lower part of the case (210) inserted into the main body (100) adjacent to the bottom of the main body (100) melts and disappears. Accordingly, the case (210) is lowered over time while the electric furnace is in operation.

In addition, as described above, the self-igniting electrode (220) protruding from the lower side of the case (210) is consumed. Accordingly, as the case (210) is lowered over time, a briquette (B) is introduced into the interior of the case (210). Accordingly, the self-igniting electrode (220) can be continuously formed while the electric furnace is operating, and the formed self-igniting electrode can protrude from the lower side of the case (210).

Hereinafter, the process in which the briquettes (B) fed into the case (210) become the self-igniting electrode (220) will be described in more detail. Since the briquettes (B) are continuously fed into the interior of the case (210), the interior space of the case (210) can be divided into a briquette zone (Z _br ), a softening zone (Z _s ), a melting zone (Z _m ), and a baking zone (Z _ba ) from the upper side where the briquettes (B) are fed to the lower side. That is, the upper space of the self-sintering electrode (220) inside the case (210) can be divided into a briquette region (Z _br ) where the injected briquette (B) is maintained in a solid state, a softening region (Z _s ) where the briquette (B) is softened by heat, a melting region (Z _m ) where the softened briquette is melted, and a firing region (Z _ba ) where the molten briquette is fired. In other words, the internal space of the case (210) can be described as including a briquette region (Z _br ), a softening region (Z _s ), a melting region (Z _m ), and a firing region (Z _ba ). At this time, since the self-sintering electrode (220) is provided when the briquette (B) is softened, melted, and fired, it can be described that the self-sintering electrode (220) is connected to the lower part of the firing region (Z _ba ).

And, during the process in which the briquette (B) is softened, melted and fired inside the case (210), the coal tar pitch and carbonaceous material contained in the briquette (B) may be carbonized, and graphite may be generated by the carbonization.

FIG. 3 is a flowchart illustrating a method for manufacturing briquettes according to an embodiment of the present invention.

Hereinafter, a method for manufacturing briquettes for manufacturing a self-igniting electrode will be described with reference to FIG. 3.

Referring to FIG. 3, a method for manufacturing a briquette includes a process (S100) of manufacturing a composition for a self-firing electrode including a carbonaceous material and coal tar pitch, and a process (S200) of manufacturing a briquette (B) using the composition for a self-firing electrode.

The process for manufacturing a composition for a self-igniting electrode includes a process of preparing a carbonaceous material (S110), a process of preparing a liquid coal tar pitch (S120), and a process of mixing the prepared carbonaceous material and the liquid coal tar pitch (S130). Each process is described in more detail below.

The process for preparing a carbonaceous material (S110) may include a process for pulverizing a carbonaceous material (S111), a process for classifying and selecting the pulverized carbonaceous material according to particle size (S112), and a process for heating the selected carbonaceous material (S113).

The carbonaceous material may include at least one of anthracite coal and coke. In this case, the coke may be at least one of needle coke and pitch coke. And at least one of the needle coke and pitch coke may be at least one of coal-based coke and petroleum-based coke.

In addition, it may be effective for the carbonaceous material to have an ash content of 5 wt% or less (0 wt% or more) contained in the carbonaceous material. That is, when a material including at least one of anthracite coal and coke is used as the carbonaceous material, it is effective for the ash content to be 5 wt% or less, and it may be more effective for it to be 3 wt% or less.

When the carbonaceous material is prepared, it is effective to first remove the volatile matter contained in the carbonaceous material. That is, it is effective to heat the carbonaceous material to a temperature of 800°C or higher so that the content of the volatile matter contained in the carbonaceous material becomes 3 wt% or less.

Carbonaceous materials, such as anthracite and coke, are solid and may be in the form of large lumps. Accordingly, the carbonaceous materials are pulverized (S111). Then, the pulverized carbonaceous materials are classified according to particle size, and it is effective to select and use those with a particle size of 1 mm to 20 mm (1 mm or more and 20 mm or less) (S112). At this time, it is more effective to select and use those with a particle size of 5 mm to 15 mm (5 mm or more and 15 mm or less).

Of course, the carbonaceous material may be pulverized to have a particle size of 1 mm to 20 mm or 5 mm to 15 mm during pulverization. In this case, the process of classifying and selecting the carbonaceous material according to particle size may be omitted.

Meanwhile, when the particle size of the carbonaceous material exceeds 20 mm, the density of the self-igniting electrode (220) manufactured using the carbonaceous material may be low. And when the density of the self-igniting electrode (220) is low, the electrical conductivity of the self-igniting electrode (220) may be reduced. On the other hand, when the particle size of the carbonaceous material is less than 1 mm, the specific surface area of the entire carbonaceous material may increase. An increase in the specific surface area of the carbonaceous material means an increase in the surface area of the carbonaceous material to be bonded or combined. Accordingly, when the specific surface area of the carbonaceous material increases, a large amount of coal tar pitch used as a binder may be required. Therefore, it may be effective to adjust the particle size of the carbonaceous material to be mixed with coal tar pitch to 1 mm to 20 mm.

When carbonaceous materials having particle sizes of 1 mm to 20 mm are prepared, the carbonaceous materials can be mixed at room temperature. That is, since the carbonaceous materials vary in the range of 1 mm to 20 mm, it is effective to mix them at room temperature to uniformly mix particles having different particle sizes.

Next, the carbonaceous material is heated (S113). That is, the carbonaceous material is first heated before mixing with the liquid coal tar pitch, and the carbonaceous material is heated to a temperature higher than the softening point temperature of the coal tar pitch. At this time, it is effective to heat the carbonaceous material to a temperature 10°C to 30°C higher than the softening point temperature of the coal tar pitch, and it is more effective to heat it to a temperature 15°C to 20°C higher than the softening point temperature of the coal tar pitch.

The reason for heating the carbonaceous material before mixing with coal tar pitch is to suppress or prevent the temperature of the coal tar pitch from decreasing when mixed with the coal tar pitch in a subsequent process. More specifically, the coal tar pitch in a solid state is heated to a temperature higher than its softening point to make it a liquid, and then the liquid coal tar pitch is mixed with the carbonaceous material. However, if the temperature of the carbonaceous material is low, the temperature of the coal tar pitch may decrease and solidify when mixed with the liquid coal tar pitch. That is, the liquid coal tar pitch may be solidified by the carbonaceous material to become a solid or its viscosity may be reduced. In this case, the carbonaceous material and the coal tar pitch may not be easily mixed. That is, the coal tar pitch may not be uniformly dispersed, the coal tar pitch may not be well attached to the particle surface of the carbonaceous material, or the coal tar pitch may not be well penetrated into the particles of the carbonaceous material. As a result, the bonding force between the particles of the carbonaceous material becomes insufficient, which becomes a factor in reducing the strength of the briquette. And if the strength of the briquette (B) is low, the briquette (B) can easily break during transportation or transport.

Therefore, the size of the briquette (B) may become small and may not be fed into the case and may be discarded. If the crushed briquette is fed into the case as is, the viscosity of the molten material formed by melting the briquette may be too low, so that some of the molten material may not be solidified. Accordingly, a liquid phase may coexist in the self-igniting electrode (220), and as a result, the electrical resistivity of the self-igniting electrode (220) may increase.

Accordingly, it is effective to heat the carbonaceous material before mixing with coal tar pitch. At this time, it is effective to heat the carbonaceous material at a temperature higher than the softening point temperature of coal tar pitch, and heating it at a temperature 10℃ to 30℃ higher may be more effective.

Meanwhile, when heating the carbonaceous material, if it is heated at a temperature lower than the softening point temperature of the coal tar pitch, or if it is heated at a temperature lower than 10℃ higher than the softening point temperature of the coal tar pitch, as described above, the coal tar pitch may solidify when mixed with the liquid coal tar pitch. On the other hand, when heating the carbonaceous material, if it is heated at a temperature higher than 30℃ higher than the softening point temperature of the coal tar pitch, the bonding strength of the coal tar pitch may be reduced. That is, coal tar pitch contains a volatile component that can provide bonding strength, but if the carbonaceous material is heated at too high a temperature, a large amount of the volatile component contained in the coal tar pitch may be vaporized and removed when the carbonaceous material and coal tar pitch are mixed. As a result, the bonding strength of the coal tar pitch may be reduced, and as a result, the bonding strength between the particles of the carbonaceous material may be insufficient, and the strength of the briquette (B) may be reduced.

Therefore, when heating a carbonaceous material, it may be more effective to heat it at a temperature 10°C to 30°C higher than the softening point temperature of coal tar pitch.

During the process of preparing the carbonaceous material in this manner (S110), liquid coal tar pitch to be mixed with the carbonaceous material is prepared (S120). The process of preparing the liquid coal tar pitch (S120) may include a process of crushing coal tar pitch (S121), a process of classifying and selecting the crushed coal tar pitch according to particle size (S122), and a process of heating and liquefying the selected coal tar pitch (S123).

Among several types or multiple types of coal tar pitch, coal tar pitch having the following characteristics is used. When coal tar pitch is heated and carbonized, coal tar pitch having a graphite a-axis crystallite length (L _a ) of 40 nm to 80 nm and a ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) (L _a /L _c ) of 2 to 3 is used. At this time, in using coal tar pitch having a graphite a-axis crystallite length (L _a ) of 40 nm to 80 nm, coal tar pitch having a graphite a-axis crystallite length (L _a ) of 50 nm to 70 nm (50 nm or more and 70 nm or less), 40 nm or more and less than 50 nm, or more than 70 nm and 80 nm or less can be used. In addition, when using a coal tar pitch having a ratio (L _a /L _c ) of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) of graphite of 2 to 3, a coal tar pitch having a ratio (L _a /L _c ) of 2.3 to 2.7 (2.3 or more and 2.7 or less), 2 or more and less than 2.3, or more than 2.7 and 3 or less can be used.

In the embodiment, coal tar pitch is used, in which the graphite formed when carbonized at 800°C to 1100°C has an a-axis crystallite length (L _a ) of 40 nm to 80 nm and a ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) (L _a /L _c ) of 2 to 3. More specifically, coal tar pitch is used, in which the graphite formed when carbonized at 950°C to 1050°C, more specifically at 1000°C, has an a-axis crystallite length (L _a ) of 40 nm to 80 nm and a ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) (L _a /L _c ) of 2 to 3.

Here, the a-axis crystallite length (L _a ) and the c-axis crystallite length (L _c ) of the graphite can be measured by X-ray diffraction analysis. That is, when coal tar pitch is heated and carbonized, graphite is generated, and X-ray diffraction analysis is performed on the graphite to measure the a-axis crystallite length (L _a ) and the c-axis crystallite length (L _a ). Then, when the a-axis crystallite length and the c-axis crystallite length of the graphite are measured, the ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) of the graphite (L _a /L _c ) can be calculated. The a-axis crystallite length (L _a ) of graphite can mean the length of the crystal in the transverse direction. Also, the c-axis crystallite length (L _c ) of graphite can mean the length of the crystallite in the vertical direction, or in other words, it can mean the thickness of the L _a plane stacked in the vertical direction.

In addition, it _{may be more effective to use a coal tar pitch having a carbonization rate of 35% to 50% while satisfying the conditions of the a-axis crystallite length (L a ) of} graphite as described above and the ratio (L _a /L _c ) of the a-axis crystallite length (L a ) to the c-axis crystallite length (L c ) of graphite. More specifically, it may be more effective to use a coal tar pitch having a carbonization rate of 35% to 50% when heated at 800° C. to 1100° C. More specifically, it may be more effective to use a coal tar pitch having a carbonization rate of 35% to 50% when heated at 950° C. to 1050° C., and even more specifically, at 1000° C. At this time, coal tar pitch having a carbonization rate of 40% to 45% (40% or more and 45% or less), 35% or more and less than 40%, or more than 45% and 50% or less can be used.

In addition, it may be more effective to use coal tar pitch having a softening point of 80℃ to 120℃. At this time, when using coal tar pitch having a softening point of 80℃ to 120℃, coal tar pitch having a softening point of 90℃ to 110℃ (90℃ or more and 110℃ or less), 80℃ or more and less than 90℃, or more than 110℃ and 120℃ or less can be selected.

And, it is effective to use coal tar pitch having an interplanar spacing d(002) of 0.3354 nm to 0.3364 nm when carbonized coal tar pitch. More specifically, it is effective to use coal tar pitch having an interplanar spacing d(002) of 0.3354 nm to 0.3364 nm when carbonized by heating at 800°C to 1100°C and then performing X-ray diffraction analysis on the carbonized coal tar pitch. More specifically, it is effective to use coal tar pitch having an interplanar spacing d(002) of 0.3354 nm to 0.3364 nm when carbonized by heating at 950°C to 1050°C, more specifically at 1000°C and then performing X-ray diffraction analysis.

The coal tar pitch used in manufacturing the briquette (B) according to the embodiment has a crystallite length of 40 nm to 80 nm in the a-axis direction of graphite as measured by the method described above, and a ratio (L _a /L _c ) of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) of graphite is 2 to 3. Accordingly, the briquette (B) including the coal tar pitch and carbonaceous material as described above can have low electrical resistivity and appropriate spreadability. Accordingly, a self-igniting electrode (220) having low electrical resistivity and high electrical conductivity can be manufactured.

A ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) of graphite (L _a /L _c ) of less than 2 may mean that the c-axis crystallite length (L _c ) of graphite is large and the a-axis crystallite length (L _a ) is small. When the ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) of graphite (L _a /L _c ) is less than 2 or the a-axis crystallite length (L _a ) of graphite is less than 40 nm, the electrical resistivity of briquettes (B) may increase and the electrical conductivity may decrease. To explain more specifically, when the ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) of graphite (L _a /L _c ) is less than 2 or the a-axis crystallite length (L _a ) of graphite is less than 40 nm, the length of the path through which electrons can move may be short due to the small a-axis crystallite length (L _a ). In addition, when the a-axis crystallite length (L _a ) of graphite is short, there are many grain boundaries or the grain boundaries are arranged closely together, and in such cases, when electrons move, the movement is often impeded by the grain boundaries. Accordingly, the electrical resistivity of the briquette (B) and the self-igniting electrode (220) manufactured using the briquette (B) increases and the electrical conductivity decreases.

In contrast, when the ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) of graphite (L _a /L _c ) exceeds 3, the electrical conductivity may also be reduced. More specifically, when the ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) of graphite (L _a /L _c ) exceeds 3, it means that the c-axis crystallite length (L _c ) of graphite or the length stacked in the c-axis direction is short, and the a-axis crystallite length (L _a ) of graphite is large. At this time, when the ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) of graphite (L _a /L _c ) exceeds 3 or the length of the a-axis crystallite of graphite (L _a ) exceeds 80 nm, the electrical conductivity of the surface of the briquette (B) is high (skin effect), but the electrical conductivity inside the briquette (B) is low. In such a case, the electrical conductivity of the inside and outside of the briquette may be different, which may cause defects in the briquette and the self-igniting electrode manufactured using the briquette. In addition, as a result, the electrical conductivity of the briquette (B) and the self-igniting electrode (220) may be reduced, which may cause a problem.

When a briquette (B) containing coal tar pitch is loaded into a case (210) of an electrode part (200) and electricity is applied to the case (210), the briquette (B) is heated and softened, melted, and sintered to manufacture a self-sintering electrode (220). While the briquette (B) is heated in this manner, the coal tar pitch contained in the briquette (B) is thermally decomposed. Then, carbon-rich amorphous carbon is generated by the thermal decomposition of the coal tar pitch, and this reaction is called a carbonization reaction, and graphite can be generated by the carbonization reaction.

And, the carbonization rate (%) is determined according to the content of carbon (C) remaining after the carbonization reaction. In other words, the carbonization rate is defined as the ratio of the amount of carbon contained in the coal tar pitch after the carbonization reaction to the content of carbon contained in the coal tar pitch before the carbonization reaction. At this time, the higher the carbon content contained in the coal tar pitch after the carbonization reaction, the higher the carbonization rate is defined.

It is effective to use a coal tar pitch used in manufacturing briquettes (B) that has a carbonization rate of 35% to 50% when carbonized. That is, when selecting a coal tar pitch, it is effective to select and use a coal tar pitch that can have a carbonization rate of 35% to 50% after carbonization at a temperature of 800°C or higher, specifically at a temperature of 800°C to 1100°C. More specifically, it is effective to select and use a coal tar pitch that can have a carbonization rate of 35% to 50% after carbonization at a temperature of 950°C to 1050°C, more specifically at a temperature of 1000°C. Accordingly, a briquette (B) having high strength and uniform density can be manufactured.

When the softening point of the coal tar pitch is less than 80℃, the liquid coal tar pitch may not penetrate well into the particles of the carbonaceous material. In this case, the bonding force between the particles of the carbonaceous material may be poor, which may reduce the strength of the briquette. On the other hand, when the softening point of the coal tar pitch exceeds 120℃, the thermal energy or electrical energy consumed to liquefy the solid coal tar pitch may be a major problem. In addition, when the softening point of the coal tar pitch exceeds 120℃, the viscosity of the liquefied coal tar pitch may be high and the fluidity may be low. When the fluidity of the coal tar pitch is low, the carbonaceous material and the coal tar pitch are not uniformly mixed, which may be a factor in reducing the strength of the briquette.

In selecting a coal tar pitch, depending on the type of coal tar pitch, carbonization is performed at a temperature of 800°C to 1100°C, and then X-ray diffraction analysis is performed to measure the c-axis crystallite length (L _c ) and the a-axis crystallite length (L _a ) of graphite, and the ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) is calculated. Then, the coal tar pitch to be used can be selected using the measurement and calculation results.

The selected coal tar pitch is in a solid state and may be in the form of large lumps. When the coal tar pitch to be used is selected, the selected coal tar pitch is pulverized (S121). Then, the pulverized coal tar pitch is classified according to particle size, and it is effective to select and use those having a particle size of 10 mm or less (exceeding 0 mm), and it is more effective to select and use those having a particle size of 5 mm or less (exceeding 0 mm) (S122). That is, it is effective to use coal tar pitch having a particle size of 10 mm or less, and it is more effective to use coal tar pitch having a particle size of 5 mm or less.

Of course, the coal tar pitch may be pulverized to have a particle size of 10 mm or less or 5 mm or less during pulverization. In this case, the process of classifying and selecting carbonaceous materials according to particle size may be omitted.

Meanwhile, if the particle size of the coal tar pitch exceeds 10 mm, the thermal energy or electrical energy consumed to liquefy the coal tar pitch may be large when the subsequent liquefaction process is performed. In addition, the smaller the particle size of the coal tar pitch, the easier it is to liquefy it. Accordingly, in the embodiment, it may be effective to use coal tar pitch having a particle size of 10 mm or less.

Next, the coal tar pitch is heated to liquefy (S123). That is, the coal tar pitch is heated to a temperature higher than the softening point temperature to liquefy it. At this time, it is effective to heat to a temperature 10℃ to 30℃ higher than the softening point temperature of the coal tar pitch.

Meanwhile, when heating coal tar pitch, if heated at a temperature lower than the softening point temperature, the coal tar pitch may not be liquefied or non-liquefied coal tar pitch may remain. In addition, if heated at a temperature higher than the softening point temperature, but lower than 10℃ higher than the softening point temperature, non-liquefied coal tar pitch may remain. Here, the remaining non-liquefied coal tar pitch may mean that solid coal tar pitch that has not become liquid remains when the heat treatment is completed. Conversely, when heating coal tar pitch at a high temperature exceeding 30℃ compared to the softening point temperature, the coal tar pitch may deteriorate. That is, a large amount of volatile matter contained in the coal tar pitch may be vaporized, which may reduce the bonding strength of the coal tar pitch.

Therefore, in heating coal tar pitch to a temperature higher than the softening point temperature, it is effective to heat to a temperature 10℃ to 30℃ higher than the softening point temperature.

When the carbonaceous material and the liquid coal tar pitch are prepared (S110, S120), they are mixed (S130). Here, the carbonaceous material is in a solid particle state and the coal tar pitch is in a liquid state, so the liquid coal tar pitch can be mixed so that it coats the surface of the carbonaceous material particle or penetrates into the interior of the particle. Accordingly, the process of mixing the carbonaceous material and the liquid coal tar pitch can be described in another way as a kneading process.

When mixing a carbonaceous material and liquid coal tar pitch, it is effective to mix so that the coal tar pitch is contained in an amount of 20 to 40 parts by weight per 100 parts by weight of the carbonaceous material. That is, by mixing so that the coal tar pitch is contained in an amount of 20 to 40 parts by weight per 100 parts by weight of the carbonaceous material, it is effective to manufacture briquettes having appropriate spreadability and low resistivity. At this time, the content of the coal tar pitch can be variously changed within the range of 20 to 40 parts by weight per 100 parts by weight of the carbonaceous material. That is, the content of the coal tar pitch can be 25 to 35 parts by weight (25 to 35 parts by weight) per 100 parts by weight of the carbonaceous material, or 20 to 25 parts by weight, or more than 35 to 40 parts by weight.

In other words, the fact that coal tar pitch is contained in an amount of 20 to 40 parts by weight with respect to 100 parts by weight of the carbonaceous material may mean that coal tar pitch is contained in an amount of 20 to 40 parts by weight with respect to 100% by weight of the carbonaceous material. In this case, the content of coal tar pitch may be 25 to 35% by weight (25 to 35% by weight) with respect to 100% by weight of the carbonaceous material, or 20 to 25% by weight, or more than 35% by weight and less than 40% by weight.

To give a more specific example of what extrapolation means, when mixing 100 kg of carbonaceous material and coal tar pitch, 25 kg to 40 kg of coal tar pitch, which is 25% to 40% of 100 kg, is mixed. In this case, the weight of the mixture of carbonaceous material and coal tar pitch is 125 kg to 140 kg.

In this way, by containing 20 to 40 parts by weight of coal tar pitch per 100 parts by weight of carbonaceous material, it is possible to manufacture briquettes having appropriate spreadability and low resistivity.

Meanwhile, when the content of coal tar pitch with respect to 100 parts by weight of the carbonaceous material is out of the range of 20 parts by weight to 40 parts by weight (20 parts by weight or more and 40 parts by weight or less), the spreadability of the briquette may be low or high, and the electrical resistivity may increase. For a more specific example, the spreadability of the briquette (B) may be low as less than 10% or high as more than 35%, or the electrical resistivity may be high as more than 120 μΩm. In addition, when the spreadability of the briquette (B) is low as less than 10%, when power is applied to the case (210) to melt the briquette (B), there may occur a problem that it is difficult to melt the briquette (B) and a large amount of power must be applied. On the other hand, when the spreadability of the briquette (B) is high as more than 35%, the viscosity of the melt formed by melting the briquette (B) may be too low, so that some of the melt may not be solidified. Accordingly, a liquid phase may coexist in the self-igniting electrode (220), which may increase the electrical resistivity of the self-igniting electrode (220). In addition, when the electrical resistivity of the briquette (B) exceeds 120 μΩm, a problem may occur in which the electrical resistivity of the self-igniting electrode (220) manufactured by the briquette (B) is high and the electrical conductivity is low.

Therefore, when mixing carbonaceous material and coal tar pitch, it is effective to mix so that the coal tar pitch is contained in an amount of 20 to 40 parts by weight per 100 parts by weight of the carbonaceous material.

When mixing carbonaceous material and coal tar pitch, it is effective to mix at a temperature higher than the softening point temperature of the coal tar pitch. More specifically, the carbonaceous material and coal tar pitch are mixed while maintaining the temperature inside a container containing the carbonaceous material and coal tar pitch at a temperature higher than the softening point temperature of the coal tar pitch. At this time, it is more effective to mix at a temperature 10°C to 30°C higher than the softening point temperature of the coal tar pitch. Accordingly, it is possible to facilitate bonding or coupling between particles of the carbonaceous material, and to suppress or prevent vaporization of volatile components contained in the coal tar pitch.

Meanwhile, when mixing carbonaceous material and coal tar pitch, if the temperature is lower than the softening point of the coal tar pitch or is mixed at a high temperature of less than 10℃ compared to the softening point, the bonding or coupling between the particles of the carbonaceous material may not be good. In this case, the density or strength of the briquette manufactured by molding the mixture (composition for self-extinguishing electrode) in which the carbonaceous material and coal tar pitch are mixed may be low. In addition, when mixing the carbonaceous material and coal tar pitch, if the temperature is higher than 30℃ compared to the softening point of the coal tar pitch, a large amount of volatile matter contained in the coal tar pitch may be vaporized and removed. In this case, the bonding strength of the coal tar pitch may be reduced. Accordingly, the strength of the briquette manufactured by molding the mixture in which the carbonaceous material and coal tar pitch are mixed may be low.

When the mixing (kneading) of the carbonaceous material and the liquid coal tar pitch is completed, the production of the composition for producing briquettes is completed. Hereinafter, the mixture of the carbonaceous material and the coal tar pitch is referred to as a 'composition for self-igniting electrode'.

Next, the composition for the self-igniting electrode is molded to manufacture a briquette (B) having a predetermined size (S200). At this time, the shape of the briquette (B) is not particularly limited and can be manufactured in various shapes such as a shell shape, a cylinder type, and a saddle-shaped shape.

The briquette (B) manufactured by the method according to the embodiment has an appropriate spreadability and a low electrical resistivity. For example, the briquette (B) may have a spreadability of 10% to 35% and an electrical resistivity of 120 μΩm or less (more than 0 μΩm).

The spreadability of the briquette (B) is the result measured or calculated by the following method. The briquette (B) is pressurized to produce a disk-shaped specimen with a diameter of 50 mm and a thickness of 50 mm. Then, the specimen is heated to 450°C at a heating rate of 10°C/min, and maintained at 450°C for 15 minutes. Then, the specimen is cooled to room temperature, and the diameter of the specimen cooled to room temperature is measured. At this time, the spreadability is calculated using the difference between the diameter of the specimen before heating (D ₁ ) and the diameter of the specimen after heating at 450°C for 15 minutes and then cooled to room temperature (D ₂ ). More specifically, it can be calculated using the method of Equation 1 below. That is, the spreadability is calculated using the diameter of the specimen that has increased after heating compared to the diameter of the specimen before heating. Another word for this spreadability may be the plasticity index.

[Formula 1]

The spreadability of the briquette (B) measured in this manner may be 10% to 35%, more preferably 15% to 25%. By adjusting the spreadability of the briquette (B) to 10% to 35%, the briquette (B) can be easily melted at an appropriate speed when charged into the case (210) and melted, and the viscosity of the melted material in which the briquette (B) is melted can be appropriately adjusted. That is, the viscosity of the melt can be an appropriate viscosity without being too low or too high. Accordingly, the electrical resistivity of the self-sintering electrode (220) formed by melting and firing the briquette (B) can be lowered and the electrical conductivity can be improved.

Meanwhile, when the spreadability of the briquette (B) is less than 10%, the briquette (B) may not melt well when the briquette is loaded into the case and heated. As a result, the briquette may have insufficient plasticity, which may lower the density of the self-sintering electrode (220) or lower the electrical conductivity. In addition, there is a problem of high power consumption to melt the briquette (B). On the other hand, when the spreadability of the briquette (B) exceeds 35%, the viscosity of the melt formed by melting the briquette (B) may be too low, so that some of the melt may not solidify. Accordingly, a liquid phase may coexist in the self-sintering electrode (220), which may increase the electrical resistivity of the self-sintering electrode (220). In addition, when the electrical resistivity of the briquette (B) exceeds 120 μΩm, there is a problem of high electrical resistivity and low electrical conductivity of the self-sintering electrode (220) manufactured by the briquette (B).

And, the briquette (B) according to the embodiment may have an electric resistivity of 120 μΩm or less, more preferably 100 μΩm or less. Accordingly, when loading the briquette (B) into the case (210) and applying power to melt and sinter the briquette (B), the power consumed can be reduced. In addition, the electric resistivity of the self-sintering electrode (220) manufactured by melting and sintering the briquette (B) can be lowered and the electric conductivity can be increased. Accordingly, even if a small amount of power is applied to the self-sintering electrode (220), the target thermal energy or arc can be generated.

Meanwhile, if the electrical resistivity of the briquette (B) exceeds 120 μΩm, the resistivity of the self-igniting electrode (220) manufactured using the briquette (B) may be high and the electrical conductivity may be low. In this case, there is a problem that a large amount of power is consumed when applying power to the self-igniting electrode (220) to generate the target heat energy or arc.

Table 1 shows the quality characteristics of briquettes manufactured by the methods according to Examples 1 to 5 and Comparative Examples 1 to 5.

Embodiments 1 to 5 and Comparative Examples 1 to 5 are briquettes manufactured by molding a composition for a self-igniting electrode including a carbonaceous material and coal tar pitch. At this time, Embodiments 1 to 5 and Comparative Examples 1 to 5 have the same content of coal tar pitch of 25 parts by weight per 100 parts by weight of the carbonaceous material. In addition, Embodiments 1 to 5 and Comparative Examples 1 to 5 differ in at least one of the type of coal tar pitch, the type of the carbonaceous material, and the content of ash contained in the carbonaceous material.

Here, the first, third, and fourth embodiments used the same coal tar pitch. That is, the coal tar pitch used in the first, third, and fourth embodiments used a coal tar pitch in which, when carbonized at 1000°C, the a-axis crystallite length (L _a ) of graphite formed was 45 nm, the c-axis crystallite length (L _c ) was 22 nm, and the ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) (L _a /L _c ) was 2.05. In addition, the coal tar pitch used in the first, third, and fourth embodiments had a carbonization ratio of 38% and a softening point of 84°C when carbonized at 1000°C. At this time, the first embodiment, the third embodiment, and the fourth embodiment differ in at least one of the type of carbonaceous material and the content of ash contained in the carbonaceous material.

The second embodiment, the fifth embodiment, and the fourth comparative example used the same coal tar pitch, and were different from the coal tar pitches used in the first embodiment, the third embodiment, and the fourth embodiment. That is, the coal tar pitches used in the second embodiment, the fifth embodiment, and the fourth comparative example had an a-axis crystallite length (L _a ) of 48 nm, a c-axis crystallite length (L _c ) of 17 nm, and a ratio of the a-axis crystallite length (L a ) to the c-axis crystallite length (L _c ) (L _a /L _c ) of 2.82 when carbonized _at 1000°C. In addition, the coal tar pitches used in the second embodiment, the fifth embodiment, and the fourth comparative example had a carbonization rate of 46% when carbonized at 1000°C, and a softening point of 92°C. At this time, the second embodiment, the fifth embodiment and the fourth comparative example are different in at least one of the type of carbonaceous material and the content of ash contained in the carbonaceous material.

In addition, Comparative Examples 1 to 3 and Comparative Example 5 differ from each other in at least one of the type of coal tar pitch, the type of carbonaceous material, and the content of ash contained in the carbonaceous material.

The fourth and fifth embodiments and the fourth comparative example each use a mixture of two types of carbonaceous materials. That is, the fourth embodiment uses a mixture of anthracite coal and pitch coke as the carbonaceous material, and the weight % ratio of the anthracite coal and pitch coke in the mixture is 'anthracite coal content: pitch coke content = 1: 1'. The fifth embodiment uses a mixture of anthracite coal and needle coke as the carbonaceous material, and the weight % ratio of the anthracite coal and needle coke in the mixture is 'anthracite coal content: needle coke content = 1: 1'. The fourth comparative example uses a mixture of needle coke and pitch coke as the carbonaceous material, and the weight % ratio of the needle coke and pitch coke in the mixture is 'needle coke content: pitch coke content = 1: 1'.

Briquettes were manufactured using the compositions for self-igniting electrodes according to the conditions of the first to fifth embodiments and the first to fifth comparative examples as described above, and the spreadability was calculated and the electrical resistivity was measured for each briquette. Then, the quality of the briquettes was evaluated using the results of the spreadability and electrical resistivity of the briquettes. At this time, when the spreadability of the briquettes was 10% to 35% and the electrical resistivity was 120 μΩm or less, the quality of the briquettes was evaluated as 'excellent'.

coal tar pitch Carbonaceous materials Briquette Content
(weight) L _a (nm) L _c (nm) L _a /L _c Carbonization rate (%) Softening point (℃) type Ash content (weight%) Spreadability (%) Electrical resistivity (μΩm) evaluation 1st
Example 25 45 22 2.05 38 84 hard coal 3 17 98 excellence 2nd
Example 25 48 17 2.82 46 92 hard coal 3 24 94 excellence 3rd
Example 25 45 22 2.05 38 84 Peach Coke 2 19 118 excellence 1st
Comparative example 25 38 16 2.38 37 77 hard coal 3 36 133 - 2nd
Comparative example 25 57 32 1.78 46 118 Peach Coke 2 15 128 - 3rd
Comparative example 25 84 37 2.27 52 125 Peach Coke 7 4 88 - 4th
Example 25 45 22 2.05 38 84 Anthracite coal + pitch coke (1:1) 3 22 74 excellence 5th
Example 25 48 17 2.82 46 92 Anthracite coal + bed coke (1:1) 2 15 69 excellence 4th
Comparative example 25 48 17 2.82 46 92 Bed coke + pitch coke (1:1) 6 39 134 - 5th
Comparative example 25 76 24 3.17 48 120 hard coal 3 8 129 -

Referring to Table 1, the first to fifth embodiments have a spreadability of 10% to 35% and a low electrical resistivity of 120 μΩm or less. That is, the first to fifth embodiments have excellent briquette quality.

However, Comparative Examples 1 to 5 have worse spreadability than Embodiments 1 to 5, or higher electrical resistivity than Embodiments 1 to 5. That is, Comparative Examples 1, 4, and 5 have spreadability exceeding the range of 10% to 35%, and electrical resistivity exceeding 120 μΩm. Accordingly, Embodiments 1 to 5 have better spreadability and electrical resistivity than Comparative Examples 1, 4, and 5. In addition, Comparative Example 2 has an electrical resistivity exceeding 120 μΩm, and Comparative Example 3 has a spreadability of less than 10%. Accordingly, Embodiments 1 to 5 have better electrical resistivity than Comparative Example 2, and better spreadability than Comparative Example 3.

This is because, in the cases of the first to fifth embodiments, coal tar pitch was _used in which the a-axis crystallite length (L _a ) of the graphite formed upon carbonization was 40 nm to 80 nm and the ratio of the a-axis crystallite length (L _a ) to the c _- axis crystallite length (L _c ) was 2 to 3, and the content of ash contained in the carbonaceous material was 5 wt% or less, but this was not the case in the cases of the first to fifth comparative examples. That is, in the first comparative example, coal tar pitch in which the a-axis crystallite length (L _a ) of the graphite formed upon carbonization was less than 40 nm was used, and in the second comparative example _{, coal tar pitch in which the ratio of the a-axis crystallite length (L a )} to the c-axis crystallite length (L _c ) of the graphite formed upon carbonization was _less than 2 was used. In addition, the third comparative example used a coal tar pitch in which the a-axis crystallite length (L _a ) of graphite formed when carbonized exceeds 80 nm. In the fourth comparative example, the a-axis crystallite length (L _a ) of graphite formed when carbonized is 40 nm to 80 nm, and the ratio of the a-axis crystallite length ( _{L a} ) to the c-axis crystallite length (L _c ) (L _a /L _c ) is 2 to 3. However, in the fourth comparative example, the content of ash contained in the carbonaceous material exceeds 5 wt%. In addition, the fifth comparative example used a coal tar pitch in which the ratio of the a-axis crystallite length (L _{a )} to _the c-axis crystallite length (L _c ) of graphite formed when carbonized exceeds 3.

From these experimental results, it can be seen that when coal tar pitch is used in which the a-axis crystallite length (L _a ) of graphite formed when carbonized is 40 nm to 80 nm and the ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) (L _a /L _c ) can be 2 to 3, briquettes having excellent spreadability and electrical conductivity can be manufactured. More specifically, it can be seen that when coal tar pitch is used in which the a-axis crystallite length (L _a ) of graphite formed when carbonized is 40 nm to 80 nm and the ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) (L _a /L _c ) can be 2 to 3, briquettes having a spreadability of 10% to 35% and a low electrical resistivity of 120 μΩm or less can be manufactured.

Next, experimental examples using the same carbonaceous material among Examples 1 to 5 and Comparative Examples 1 to 5 will be described by comparison. When Examples 1 and 2 and Comparative Example 1 and Comparative Example 5 are compared, they use anthracite coal as the carbonaceous material in the same way, and the content of ash contained in the carbonaceous material is the same at 3 wt%. However, Examples 1 and 2 and Comparative Example 1 and Comparative Example 5 use different types of coal tar pitch. When Embodiment 1, Embodiment 2, Comparative Example 1 and Comparative Example 5 are compared, Comparative Example 1 has a spreadability of greater than 35% and a high electrical resistivity exceeding 120 μΩm, while Comparative Example 5 has a small spreadability of less than 10% and a high electrical resistivity exceeding 120 μΩm. On the other hand, the first and second embodiments have a spreadability of 10% to 35% and a low electrical resistivity of 100 μΩm or less. That is, the spreadability and electrical resistivity of the first and second embodiments are superior to those of the first and fifth comparative examples.

This is because, in the case of the first and second embodiments, a coal tar pitch was used in which the a-axis crystallite length (L _a ) of the graphite formed upon carbonization was 40 nm to 80 nm and the ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) (L _a /L _c ) was 2 to 3, but this was not the case in the first and fifth comparative examples. That is, the first comparative example used a coal tar pitch in which the a-axis crystallite length (L _a ) of the graphite formed upon carbonization was less than 40 nm, and the fifth comparative example used a coal tar pitch in which the ratio of the a-axis crystallite length (L _{a )} to the c- _axis crystallite length (L _c ) of the graphite formed upon carbonization was more than 3.

As another example, the third embodiment and the second comparative example used pitch coke as the same carbonaceous material, and the content of ash contained in the carbonaceous material was the same at 2 wt%. However, the third embodiment and the second comparative example used different types of coal tar pitch. The third embodiment and the second comparative example both had spreadability of 10% to 35%. However, the second comparative example had an electrical resistivity exceeding 120 μΩm, while the third embodiment had a low electrical resistivity of 120 μΩm or less. That is, the electrical resistivity of the third embodiment is superior to that of the second comparative example.

This is because, in the case of the third embodiment, a coal tar pitch was used in which the a-axis crystallite length (L _a ) of the graphite formed upon carbonization was 40 nm to 80 nm, and the ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) (L _a /L _c ) was 2 to 3, but this was not the case in the second comparative example. That is, the second comparative example used a coal tar pitch in which the ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) of the graphite formed upon carbonization (L _a /L _c ) was less than 2.

From the results of comparing the first and second embodiments, the first comparative example, and the fifth comparative example, and the results of comparing the third embodiment and the second comparative example, it can be seen that at least one of the spreadability and the electrical conductivity is different depending on the coal tar pitch regardless of the type of the carbonaceous material. That is, when using a coal tar pitch in which the a-axis crystallite length (L _a ) of graphite formed when carbonized is 40 nm to 80 nm and the ratio of the a-axis crystallite length ( _{L a} ) to the c-axis crystallite length (L c ) (L _a /L _c ) can be 2 to 3, it can be seen that briquettes having excellent spreadability and electrical conductivity can be manufactured. That is, it can be seen that briquettes having a spreadability of 10% to 35% and a low electrical resistivity of 120 μΩm or less can be manufactured.

Table 2 shows the quality characteristics of briquettes manufactured by the methods according to the first embodiment, the sixth to eighth embodiments, and the sixth and seventh comparative examples.

Embodiment 1, Embodiments 6 to 8, and Comparative Examples 6 and 7 are briquettes manufactured by molding a composition for a self-igniting electrode including a carbonaceous material and coal tar pitch. Here, Embodiment 1 is the same as Embodiment 1 described in Table 1. And, Embodiment 1, Embodiments 6 to 8, and Comparative Examples 6 and 7 used the same carbonaceous material and the same coal tar pitch. That is, Embodiment 1, Embodiments 6 to 8, and Comparative Examples 6 and 7 used anthracite as the carbonaceous material, and the content of ash contained in the carbonaceous material was the same at 3 wt%. In addition, the first embodiment, the sixth to eighth embodiments, and the sixth and seventh comparative examples used coal tar pitch having an a-axis crystallite length (L _a ) of 45 nm, a c-axis crystallite length (L _c ) of 22 nm, a ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) of 2.05, and a carbonization rate of 38% when carbonized at 1000 _{° C} . In addition, coal tar pitch having a softening point of 84°C was used.

However, the contents of coal tar pitch in the first embodiment, the sixth to eighth embodiments, and the sixth and seventh comparative examples are different from each other. That is, in terms of the content of coal tar pitch with respect to 100 parts by weight of the carbonaceous material, the first embodiment, the sixth to eighth embodiments have 20 parts by weight to 40 parts by weight, the sixth comparative example has 15 parts by weight, and the seventh comparative example has 45 parts by weight.

Briquettes were manufactured using the compositions for self-igniting electrodes according to the conditions of the first embodiment, the sixth to eighth embodiments, and the sixth and seventh comparative examples as described above, and the spreadability was calculated and the electrical resistivity was measured for each briquette. Then, the quality of the briquettes was evaluated using the results of the spreadability and electrical resistivity of the briquettes. At this time, when the spreadability of the briquette was 10% to 35% and the electrical resistivity was 120 μΩm or less, the quality of the briquettes was evaluated as 'excellent'.

coal tar pitch Carbonaceous materials Briquette Content
(weight) L _a (nm) L _c (nm) L _a /L _c Carbonization rate (%) Softening point (℃) type Ash content (weight%) Spreadability (%) Electrical resistivity (μΩm) evaluation 1st
Example 25 45 22 2.05 38 84 hard coal 3 17 98 excellence 6th
Comparative example 15 45 22 2.05 38 84 hard coal 3 37 125 - 6th
Example 20 45 22 2.05 38 84 hard coal 3 33 117 excellence 7th
Example 30 45 22 2.05 38 84 hard coal 3 24 98 excellence 8th
Example 40 45 22 2.05 38 84 hard coal 3 19 87 excellence 7th
Comparative example 45 45 22 2.05 38 84 hard coal 3 7 77 -

Referring to Table 2, Embodiments 1 and 6 to 8 have a spreadability of 10% to 35% and an electrical resistivity of 120 μΩm or less. However, Comparative Example 6 has a spreadability of over 35% and an electrical resistivity of over 120 μΩm, and Comparative Example 7 has a spreadability of less than 10%. That is, Embodiments 1 and 6 to 8 have a better spreadability and electrical resistivity than Comparative Example 6, and a better spreadability than Comparative Example 7.

This is because, in the case of the first embodiment and the sixth to eighth embodiments, the content of coal tar pitch with respect to 100 parts by weight of the carbonaceous material is 20 parts by weight to 40 parts by weight, but this is not the case with the sixth and seventh comparative examples. That is, in the content of coal tar pitch with respect to 100 parts by weight of the carbonaceous material, the sixth comparative example is less than 20 parts by weight, and the seventh comparative example is more than 40 parts by weight.

From these experimental results, it can be seen that when mixing carbonaceous material and coal tar pitch, it is more effective to mix so that the content of coal tar pitch is 20 to 40 parts by weight per 100 parts by weight of carbonaceous material.

According to embodiments of the present invention, coal tar pitch is used as a binder. At this time, coal tar pitch is used which, when carbonized, has an a-axis crystallite length (L _a ) of 40 nm to 80 nm as determined by X-ray diffraction analysis of graphite, and a ratio (L _a /L _c ) of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) of 2 to 3. Accordingly, even if a briquette (B) is manufactured with a composition containing a small amount of coal tar pitch, the electrical resistivity of the briquette (B) can be lowered and appropriate spreadability can be secured. Accordingly, the electrical resistivity of a self-firing electrode (220) manufactured by melting and firing the briquette (B) can be reduced, and the electrical conductivity can be improved. In addition, in manufacturing molten metal by melting raw materials with heat and arc generated by applying power to the self-igniting electrode (220), the efficiency of heat and arc generated from the self-igniting electrode (220) by the applied power can be increased.

In addition, the amount of coal tar pitch used for manufacturing briquettes (B) or self-igniting electrodes (220) and the resulting cost can be reduced. In addition, as the amount of coal tar pitch to be liquefied is reduced, the cost and time required for liquefaction can be reduced.

100: Body 200: Electrode
210: Case 220: Self-charging electrode
B: Briquette

Claims (17)

A composition for a self-igniting electrode that can be used in an electric furnace,
Containing carbonaceous material containing carbon and coal tar pitch,
The above-mentioned coal tar pitch is a composition for a self-igniting electrode, wherein the a-axis crystallite length (L _a ) measured by X-ray diffraction analysis of graphite formed when carbonized is 40 nm to 80 nm, and the ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) (L _a /L _c ) is 2 to 3. In claim 1,
A composition for a self-igniting electrode, wherein the content of the coal tar pitch is 20 to 40 parts by weight per 100 parts by weight of the carbonaceous material. In claim 1,
The above-mentioned coal tar pitch is a composition for a self-igniting electrode having a carbonization rate of 35% to 50% when carbonized. In claim 1,
A composition for a self-igniting electrode, wherein the ash content among 100 wt% of the above carbonaceous material is 0 wt% or more and 5 wt% or less. In claim 4,
A composition for a self-igniting electrode, wherein the content of volatile matter among 100 wt% of the above carbonaceous material is 0 wt% or more and 3 wt% or less. In claim 4,
A composition for a self-igniting electrode, wherein the carbonaceous material comprises at least one of anthracite coal and coke. In claim 6,
A composition for a self-firing electrode, wherein the coke comprises at least one of needle coke and pitch coke. In claim 7,
A composition for a self-firing electrode, wherein at least one of the above-mentioned needle coke and pitch coke is at least one of coal-based coke and petroleum-based coke. A briquette manufactured by molding a composition for a self-igniting electrode according to any one of claims 1 to 8. In claim 9,
The above briquette has an electrical resistivity of more than 0μΩm and less than or equal to 120μΩm,
The above briquette is a briquette having a spreadability, which is a ratio of the increase in the diameter (D ₂ ) of the briquette after heating to the diameter (D ₁ ) of the briquette before heating, of 10% to 35%. Process of preparing carbonaceous materials;
A process for preparing coal tar pitch, wherein the a-axis crystallite length (L _a ) measured by X-ray diffraction analysis of graphite formed when carbonized is 40 nm to 80 nm, and the ratio of the a-axis crystallite length (L _a ) to the c-axis crystallite length (L _c ) (L _a /L _c ) can be 2 to 3;
A process for manufacturing briquettes comprising the above-mentioned prepared carbonaceous material and coal tar pitch;
The process of inserting the briquette into the interior of the case of the electrode part installed to be inserted into the main body of the electric furnace; and
A method for manufacturing an electrode part, comprising: a process of applying power to the case to melt and sinter the briquette to form a self-igniting electrode that can protrude outside the case. In claim 11,
The above-mentioned prepared coal tar pitch is high-grade,
Before manufacturing the above briquette, a process of heating the prepared carbonaceous material and a process of liquefying the prepared solid coal tar pitch by heating it to a temperature higher than the softening point,
The process of manufacturing the above briquettes is as follows:
A process of mixing the above heated carbonaceous material and liquefied coal tar pitch;
A method for manufacturing an electrode part, comprising: a process of molding a mixture of the above carbonaceous material and coal tar pitch. In claim 12,
A method for manufacturing an electrode part, wherein the prepared carbonaceous material is heated so that the temperature of the carbonaceous material becomes higher than the softening point of the coal tar pitch. In claim 13,
In heating the above carbonaceous material so that the temperature is higher than the softening point of the coal tar pitch,
A method for manufacturing an electrode part, wherein the temperature of the carbonaceous material is heated to a temperature 10°C to 30°C higher than the softening point of the coal tar pitch. In claim 11,
A method for manufacturing an electrode part, wherein the carbonaceous material is prepared by preparing the carbonaceous material, wherein the ash content is 0 wt% or more and 5 wt% or less among 100 wt% of the carbonaceous material, and the volatile matter content is 0 wt% or more and 3 wt% or less. In claim 12,
In mixing the above carbonaceous material and liquefied coal tar pitch,
A method for manufacturing an electrode part by mixing the carbonaceous material and liquefied coal tar pitch while heating them at a temperature higher than the softening point of the coal tar pitch. As an electrode part that is installed so that a part is inserted into the main body of the electric furnace,
A case having an internal space formed to extend in one direction; and
An electrode part including a self-firing electrode formed by firing the briquette described in claim 9, with a part positioned inside the case and the remainder protruding outside the lower side of the case.

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