JPH0824068B2 - Metal melting and refining method and electrode cooling device used therefor - Google Patents

Description

The present invention relates to a method for melting and refining metal and an electrode cooling device provided therewith, and more specifically, in an arc electric furnace, they are sequentially connected through a nipple. When melting and refining the metal by passing a current through the graphite electrode, the cooling liquid such as cooling water is continuously sprayed on the outer peripheral surface of the upper graphite electrode held by the electrode holder to cool it. Injecting the cooling liquid at an inclination angle of 10 to 35 ° with respect to the horizontal level and spraying it upwards and spraying it on the outer peripheral surface of the graphite electrode to minimize the scattering of the cooling liquid when spraying the graphite. The electrode is cooled effectively, the oxidation consumption of the graphite electrode outer surface is suppressed, and the electrode unit consumption can be greatly reduced.Furthermore, spraying cooling water improves the life of the electric arc furnace lid and increases the high voltage and high voltage. Method of melting and refining metal by power factor operation And the electrode cooling device provided therewith.

Conventional technology Conventionally, in the electric arc melting and refining of steel and metal, along with the reduction of the electric energy cost, the oxidation consumption of the tip and outer peripheral surface of the graphite electrode is suppressed, thereby reducing the electrode unit consumption. It is desired to let them do. It has been proposed to cool the graphite electrode as a means for suppressing this oxidative consumption, and as one of the cooling methods, the upper electrode of the sequentially connected graphite electrodes has a structure of cooling the inside with cooling water, that is, It is configured as a water-cooled non-consumable electrode, and a graphite electrode is connected to the lower end of this non-consumable electrode via a nipple, and the lower non-consumable electrode is cooled by cooling the upper non-consumable electrode during refining operations such as melting. However, there has been proposed a method and an apparatus for refining by consuming only the graphite electrode. For example, U.S. Pat.
No., 4.417.344 and 4.451.926 specifications,
A structure in which a water-cooled non-consumable electrode is composed of an aluminum hollow cylinder, cooling water is introduced into the non-consumable electrode, and the cooling water cools the wall surface of the non-consumable electrode and the graphite electrode connected to the lower end. Are listed.

In addition, JP-A-60-501879 and JP-A-60-
In each specification of 501880, a water-cooled non-consumable electrode is composed of a tubular body made of graphite, and cooling water is introduced into the center hole of the non-consumable electrode, and the cooling water causes the wall surface of the non-consumable electrode to flow. And a structure for cooling a graphite electrode connected thereto.

When the graphite electrode connected to the lower part is cooled by cooling the non-consumable electrode at the upper end in this way, the oxidation consumption of the tip end portion and the outer peripheral portion of the graphite electrode is suppressed, and the electrode unit consumption can be reduced.

However, the graphite electrode connected to the lower part is consumed, and when this graphite electrode is removed, it is moved off-line from the electrode furnace to remove the used graphite electrode from the nipple, and when necessary, the nipple is also removed from the non-consumable electrode. When connecting a new graphite electrode, a nipple is attached to the non-consumable electrode, and a new graphite electrode is attached to this nipple. Therefore, when cooling the graphite electrode connected to the lower part by the water-cooled non-consumable electrode as described above,
The graphite electrodes must be transferred offline for replacement, where heavy-duty labor must be removed and connected, which complicates the work. When the graphite electrode is repeatedly removed and connected, the graphite electrode, the non-consumable electrode,
The threads of the nipple or the like may be deformed, crushed, or damaged, resulting in poor connection, increased electrical resistance, etc., resulting in operational problems.

From this point, as described above, in order to cool the graphite electrode connected to the lower part, without using a water-cooled non-consumable electrode, in Japanese Utility Model No. 59-23357, from the furnace lid of the arc electric furnace A cooling device is described in which cooling water is sprayed onto the surface of a graphite electrode protruding upward to cool the surface, and the cooling device is configured as shown in FIG. That is, in FIG. 2, reference numeral 1 denotes a furnace lid of an arc electric power furnace, a graphite electrode 2 is vertically inserted through the furnace lid 1, and a graphite electrode is connected to a lower portion of the graphite electrode 2 and a lower portion of the lower portion. Graphite is located in the arc electric furnace, and refining such as steelmaking is performed. Above the furnace lid 1, the upper end of the graphite electrode 2 is held by the electrode holder 3. An annular cooling pipe 4 that surrounds the outer circumference of the graphite electrode 2 is provided on the lower surface of the electrode holder 3, and a plurality of vertical pipes 5 are projected downward from the annular cooling pipe 4, and graphite is provided on the inner surface of each vertical pipe 5. A nozzle 6 is provided which is directed toward the electrode surface. Therefore, the annular cooling pipe 4
The cooling water supplied to the pipes descends along the vertical pipes 5, and the cooling water is sprayed from the inner nozzles 6 onto the outer peripheral surface of the graphite electrode to be cooled.

However, in the cooling device shown in FIG.
The cooling water is jetted from the horizontal level or a direction parallel to the horizontal level. Therefore, when the cooling water collides with the outer peripheral surface of the graphite electrode 2, a considerable amount of it is reflected and scattered, and the scattered cooling water is large.
The furnace lid 1 is severely contaminated and damaged, and cannot be put to practical use. Further, of the injected cooling water, only a small amount contributes to cooling, so that the amount of cooling water used becomes abnormally large, which is extremely uneconomical. Further, a large number of vertical pipes 5 project downward from the cooling pipe 4, and the projecting length thereof is extremely long. For this reason, this long vertical pipe 5 becomes an obstacle when the cooling device is removed during electrode replacement, and handling is extremely troublesome.

In addition to the above-mentioned drawbacks, the cooling device shown in FIG. 2 has a ring-shaped cooling pipe 4 surrounding the outer periphery of the graphite electrode 2. Therefore, the cooling pipe 4 shields electromagnetic force from A considerable part of the current flowing through the electrode 2 is cut off,
The operation will be seriously hindered. That is, in the operation of the arc electric furnace, usually, three graphite electrodes are used corresponding to the three-phase AC power source, and when cooling the graphite electrodes, each graphite electrode is provided with the cooling device shown in FIG. For this reason, since each cooling pipe 4 is ring-shaped, electromagnetic influence is exerted between the graphite electrodes 2 while the cooling pipes 4 shield the electromagnetic force so that the current of the graphite electrode 2 is interrupted and metal is removed. It is not preferable because electric power cannot be sufficiently heated by heating, and the power consumption rate is greatly increased.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention aims to solve these problems, specifically, by injecting a cooling liquid at an inclination angle of 10 to 35 ° C. upward with respect to a horizontal level, (EN) A method for melting and refining a metal in which jetted cooling water is looped and sprayed on the outer peripheral surface of a graphite electrode, and an electrode cooling device used for the method.

<Structure of the Invention> Means for Solving the Problem and Its Action That is, the method of the present invention is such that the cooling liquid is sprayed onto the outer peripheral surface of the graphite electrodes sequentially connected through the nipple to cool the metal. When melting and refining, the cooling liquid is sprayed at an inclination angle of 10 to 35 ° with respect to the horizontal level, and the sprayed cooling liquid is looped and sprayed on the outer peripheral surface of the graphite electrode. And

Further, in an apparatus suitable for carrying out this, between the furnace lid of the arc electric furnace and the electrode holder which holds the upper end of the graphite electrode, the graphite electrode is surrounded and the cooling liquid flows. In an electrode cooling device in which an annular cooling pipe is arranged and at the time of melting and refining a metal sprayed with a cooling liquid from the inner peripheral surface of the annular cooling pipe facing the outer peripheral surface of the graphite electrode, at least one place of the annular cooling pipe is provided. At least one which forms a notch by forming a notch, injects a cooling liquid on the inner peripheral surface of the annular cooling pipe, is inclined upward by 10 to 35 ° with respect to the horizontal level, and is directed in the central axis direction of the graphite electrode. Provide an injection hole.

The structure and operation of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view showing an example of an embodiment of the method of the present invention, and FIG. 2 is a perspective view of a cooling device according to a conventional example.

First, the present invention is, for example, as shown in Japanese Utility Model Publication No. 59-23357, the outer peripheral surface of the upper end portion of the graphite electrodes sequentially connected via a nipple, by cooling by directly spraying a cooling liquid, It is a method of melting and refining metals.

However, in the present invention, the cooling water is not sprayed at the horizontal level, but the cooling water is jetted and sprayed at an upward inclination angle of 10 to 35 ° with respect to the horizontal level. Therefore, the cooling liquid takes a loop and hits the outer peripheral surface of the graphite electrode,
Part of it does not scatter very much and descends along the outer peripheral surface, and the outer peripheral surface of the graphite electrode is cooled by this cooling liquid film, and the cooling is not locally limited at the outer peripheral surface and is cooled to a black state. The length of the portion kept at is increased, and the oxidation consumption of the connected graphite electrode can be greatly reduced.

Further, the cooling water may be water, or an antioxidant may be contained in the cooling liquid. Therefore, when the cooling liquid descends along the outer peripheral surface of the graphite electrode, the oxidation resistant agent contained therein adheres, and the oxidation resistant film formed by this adhesion effectively prevents the graphite electrode from being oxidized and consumed. it can.

In addition, the cooling liquid injection pressure 0.5 to 3 kg / cm ² , injection amount 0.8 to
Spray at 6.0 / min. Therefore, if sprayed in this range, the cooling liquid will not scatter at all during spraying, and the cooling liquid will evaporate instantly even if it descends along the outer peripheral surface of the graphite electrode and enters the furnace. Since it vaporizes, there will be no operational problems in the electric furnace.

Further, as described above, when carrying out the present invention, an annular cooling pipe is arranged between the furnace lid of the electric arc furnace and the electrode holder that holds the upper end of the graphite electrode. Spray nozzles are provided on the peripheral surface, and the cooling liquid is sprayed from the spray nozzles to the outer peripheral surface of the graphite electrode. At least one location of this annular cooling pipe is cut out to form a cutout portion. Therefore, even if it is affected by the electromagnetic current of the graphite electrode,
No current flows through the cooling tube due to the presence of the cutout portion, so that the current flowing through the graphite electrode is not interrupted. Further, at least one spray nozzle provided on the inner peripheral surface of the annular cooling tube is inclined at an inclination angle of 10 to 35 ° upward with respect to the horizontal level and directed toward the central axis of the graphite electrode. As described above, the injection hole for injecting the cooling liquid is provided in the annular cooling pipe. Therefore, the cooling liquid from the spray nozzle is jetted with an upward inclination, and the cooling liquid is looped and collides with the outer peripheral surface of the graphite electrode, and at that time, considerable injection energy may be lost. , And flows down along the outer peripheral surface without being scattered around to form a cooling liquid layer. Therefore, the outer peripheral surface of the graphite electrode held by the electrode holder can be uniformly cooled over the entire length, and the graphite unit can be greatly reduced.

First, in FIG. 1, reference numeral 10 indicates a graphite electrode,
The upper end of this graphite electrode 10 is gripped by an electrode holder, and the lower end is connected to a graphite electrode via a nipple,
The graphite electrode to be connected is put in an electric furnace through the furnace lid.

Further, when the graphite electrode 10 is arranged in the electric furnace, a circle with a predetermined radius is drawn centering on the center of the electric furnace,
Three graphite electrodes are arranged at intervals so as to be located on this circular circle. The three graphite electrodes are arranged here because a three-phase alternating current is used as a power source. However, in FIG. 1, one graphite electrode 10 is shown as a typical example, but in three graphite electrodes, each graphite electrode 10 has a graphite electrode in the lower part through the nipple as described above. Are connected to each other, and current is applied to each of these electrodes in an electric furnace to melt and refine metal such as steelmaking.

Therefore, at least one of these three graphite electrodes
An outer peripheral surface 10a of one graphite electrode 10, specifically, an outer peripheral surface 10a of the graphite electrode 10 is continuously sprayed with a cooling liquid 11 made of, for example, water between the electrode holder and the furnace lid. At this time, the cooling liquid 11 is not parallel to the horizontal level L-L but is inclined upward with respect to the horizontal level L-L at an inclination angle of 10 to 35 [deg.] To be sprayed and cooled.

That is, when the cooling liquid 11 is sprayed on the outer peripheral surface 10a of the graphite electrode 10 to cool, the cooling liquid 11 can be sprayed and cooled by any method, but the cooling liquid 11 is jetted substantially parallel to the horizontal level L-L to cool the graphite. When the outer peripheral surface 10a of the electrode 10 is sprayed, the collision energy at the time of spraying is increased, and a considerable portion of the cooling liquid 11 is scattered to the outside, and only the collision portion of the outer peripheral surface 10a of the graphite electrode 10 is locally cooled. Can not. Further, the scattered cooling water accelerates the wear of the electrode holder and the furnace lid. From this point, in the present invention, the cooling pipe 16 is arranged outside the graphite electrode 10, and the cooling liquid 11
Is tilted upward at an angle of inclination of 10 to 35 ° and sprayed.
The cooling pipe 16 is arranged between the electrode holder that holds the upper end of the graphite electrode 10 and the upper lid (not shown) of the electric arc furnace, and preferably the cooling pipe 16 is arranged immediately below the electrode holder.

The cooling pipe 16 is formed in an annular shape concentric with the graphite electrode 10 so as to be separated from the outer peripheral surface 10a of the graphite electrode 10 by a predetermined distance. Provide a notch. That is, as described above, for example, three graphite electrodes 10 are arranged concentrically around the center of the electric arc furnace, and when the graphite electrodes are connected to the respective graphite electrodes to operate, the graphite electrodes 10 and Each graphite light pole depends on the current flowing through the connected graphite electrode.
Each cooling pipe 16 surrounding 10 is electromagnetically affected either alone or with each other. Due to the electromagnetic influence of the cooling pipe 16, a part of the current flowing through the graphite electrode 10 and the graphite electrode connected to the graphite pipe 10 is cut off and the operation of the electric furnace is impaired. Therefore, in consideration of this electromagnetic influence, a cutout portion is provided in a part of the cooling pipe 16 so that the cooling pipe 16 is not affected by the electromagnetic influence. In simple terms, as described above, in the arc electric furnace, since three-phase alternating current is used as the power source, three graphite electrodes 10 are arranged concentrically corresponding to each alternating current. Therefore, these graphite electrodes 10 electromagnetically influence each other, and this influence is affected by the surrounding cooling tubes.
If the cooling pipe 16 is continuous in an annular shape by receiving the current 16, an electric current flows, and the electric current causes an electric current to flow through the graphite electrode 10 due to an electromagnetic effect, which hinders the operation. However, if a notch is provided in a part of the cooling pipe 16, a current will be induced in the cooling pipe 16 to flow even if it is electromagnetically affected by the graphite electrode 10 inside and the surrounding graphite electrode 10. There is no problem, and there is no problem in operation.

The cooling pipe 16 is made of a material that is not affected by electromagnetic effects, has excellent oxidation resistance, and has excellent moldability. For example, stainless steel, which is a non-magnetic material when it is made of a metal material due to moldability, is used. It is preferable to be composed of Even if it is made of a material other than a metal material, it can be made of a material that is not affected by electromagnetic effects, such as ceramics, and has oxidation resistance.

Further, in order to spray and spray the cooling liquid 11 from the inner peripheral surface of the cooling pipe 16, a plurality of, for example, 4 to 8 spray nozzles are provided on the inner peripheral surface of the cooling pipe 16 at intervals. . Each spray nozzle is directed in the radial direction toward the center of the graphite electrode 10, and the tip nozzle portion of each spray nozzle is diagonally upward,
Inclination angle θ = 10 to 35 °. When the cooling liquid is sprayed while inclining in this range, the cooling liquid 11 continuously supplied from the introduction duct is jetted obliquely upward from each spray nozzle of the cooling pipe 16 as shown in FIG. That is,
When the cooling liquid 11 is tilted upward and sprayed, the graphite electrode 10
When colliding with the outer peripheral surface 10a, the collision energy is relaxed, the cooling liquid 11 scarcely scatters, and moreover, since it is directed upward, a thin cooling liquid film along the outer peripheral surface 10a of the graphite electrode 10. 11a is formed. Therefore, while the film 11a descends along the outer peripheral surface 10a of the graphite electrode 10, the cooling liquid 11 is vaporized by the heat inside the graphite electrode 10, and the heat of vaporization causes the heat retained by the graphite electrode 10 to be And is cooled well over its entire length. When the upper graphite electrode 10 is cooled in this manner, the graphite electrode connected to the lower end of the upper graphite electrode 10 is cooled by the upper graphite electrode, and the oxidation consumption of the lower graphite electrode is suppressed.

In other words, since the graphite electrode has excellent conductivity, the upper part of the graphite electrode held by the electrode holder is cooled,
When it is cooled as far as possible to the lower end, the graphite electrode connected to the lower part is also cooled well, and the electrode unit consumption is greatly reduced.

Further, when cooled in this way, the cooling liquid 11 is formed as a film 11a on the outer peripheral surface 10a of the graphite electrode 10 held by the electrode holder, and a part thereof enters into the upper lid of the electric furnace. Sometimes the temperature inside the electric furnace is very high,
When the contained cooling water is not large, it evaporates and does not hinder the operation. However, when the upper lid is made of a refractory material such as magnesia, it is not preferable because it impregnates with water to lubricate it and deteriorate its brittleness. For this purpose, the injection pressure of the cooling liquid 11 is
It is preferable to adjust the injection amount of 0.5 to 3 kg / cm ² within the range of 0.8 to 6.0 / min.

Generally, when the cooling water reaches the molten metal which is being melted and refined in an electric furnace, the water contained therein comes into contact with the high temperature molten metal to cause hydrogen explosion, which is extremely dangerous. From this point,
Without spraying a cooling liquid such as cooling water on the outer peripheral surface 10a of the graphite electrode 10, the upper electrode held by the electrode holder is configured as a non-consumable electrode into which cooling water can be introduced, as described above. Specifically, a cooling passage is formed along the central axis and is cooled by this cooling passage.

Contrary to this, when the cooling liquid 11 is sprayed on the outer peripheral surface 10a of the graphite electrode 10 as in the present invention, the outer peripheral surface 10a of the graphite electrode 10 is cooled by the cooling liquid 11, and the cooling is performed over a wide range as much as possible, and further, the cooling liquid. It is necessary to keep the spray amount of 11 to a minimum so that even if the cooling liquid 11 enters the upper lid, it is quickly vaporized in the furnace so that the above-mentioned trouble does not occur.

More specifically, when the graphite electrodes are sequentially connected from the upper side without using the non-consumable electrode and only the upper graphite electrode is cooled, the connection of the electrodes does not change from normal operation. Therefore, it is most suitable for on-site operation.
Moreover, since the graphite of the upper and lower graphite electrodes is a very good heat conductive material, it is an extremely excellent cooling method. However, since the lower graphite electrode is cooled by the upper graphite electrode, the cooling effect of the lower graphite electrode depends on the cooling effect of the upper graphite electrode. In other words, the reduction rate of the graphite electrode basic unit is determined by how much the upper graphite electrode is cooled in the longitudinal direction. By the way, it is sometimes said that the upper part of the graphite electrode, for example, if only the upper end is in a black state without red heat, the lower part connected below it. It is said that the wear of the graphite electrode on the outer circumference and the tip is substantially suppressed.
For example, in the upper graphite electrode 10% of its length
It is said that when the degree remains black and the others are red-heated, the ratio of the electrode unit consumption is reduced to 12% or more in the lower graphite electrode due to the suppression of oxidation consumption.

In this respect, when the cooling liquid is sprayed directly on the outer peripheral surface of the upper graphite electrode to cool it, if the cooling liquid is sprayed with an upward inclination as in the above example, the graphite electrode is spread over a wide area in the longitudinal direction. Can be cooled. In other words, 10% or more of the upper graphite electrode, to which the cooling liquid is directly applied, can be maintained in a black state without red heat, so that the electrode unit can be greatly reduced.

Further, as described above, when the cooling liquid is sprayed on the outer peripheral surface of the graphite electrode to form the cooling liquid film on the outer peripheral surface, the cooling liquid 11 is inclined upward with respect to the horizontal level L-L (inclination angle θ = (10 to 35 °), and the cooling liquid 11 is looped and brought into contact with the outer peripheral surface 10a of the graphite electrode 10. When the cooling liquid 11 is sprayed in this way, the cooling liquid 11 can be sprayed onto the outer peripheral surface 10a of the graphite electrode without waste, and the upper lid 15 of the electric arc furnace is composed of a magnesia-based refractory material that becomes brittle due to water impregnation. However, almost without cooling liquid 11 covering the top lid 15,
There are no operational problems. Even if the upper lid 15 is durable against moisture and is made of an alumina refractory, spraying the cooling liquid 11 upward without waste will make the life of the upper lid 15 longer than that of spraying the cooling liquid 11 downward. It will be improved by 1.5 to 2.0 times or more.

Further, as shown in FIG. 1, a cooling nozzle 16 may be provided in the cooling pipe 16 for spraying the cooling liquid 11 while inclining it upward, but normally at least one injection hole 16a has an upward inclination angle. It can be provided with an inclination under the condition of θ = 10 to 35 °. The cooling pipe 16 is partially formed with a notch. Further, at the time of cooling, the cooling pipe 16 can be arranged directly below the electrode holder that holds the graphite electrode 10,
It can also be arranged on the surface of the upper lid 15.

Further, as described above, it is preferable that the distance between the outer peripheral surface 10a of the graphite electrode 10 and the tip nozzle of the spray nozzle or the injection hole 16a is about 5 to 20 cm when cooling using the cooling pipe 16. The cooling liquid 11 is at the horizontal level L
It is configured to inject at an inclination angle of 10 to 35 ° with respect to -L, and the cooling liquid 11 is sprayed at a pressure of 0.5 to 3 kg / cm ^2.
It is preferable to inject at 0.8 to 6.0 / min.

Under such preferable conditions, even if the dimensions, dimensions, and capacity of the arc electric furnace are changed to some extent, if the arc electric furnace is currently put into practical use, the cooling liquid 11 does not waste the outer circumference of the graphite electrode 10. The surface 10a can be cooled well, it does not scatter on the electrode holder or the upper lid so much, and the life can be greatly improved.

That is, in addition to the above reason, the reason why the inclination angle θ (see FIG. 1) of the spray nozzle is set in the range of 10 to 35 ° when the cooling liquid is sprayed with the spray tilted upward is tentatively. When the spray angle is 0 ° and the cooling liquid 11 is sprayed from the spray nozzle in parallel with the horizontal level L-L, the graphite electrode 10 can be cooled only locally unless the amount of the cooling liquid 11 is greatly increased. At most, only about 5% of the length can be kept black. Further, during spraying, a considerable portion of the cooling liquid 11 is scattered to the electrode holder side, and the electrode holder itself is easily damaged. From this point as well, the lower limit is preferably 10 °. Further, if the inclination angle θ is inclined at 35 ° or more, the cooling liquid 11 spreads and a part of it spreads on the upper lid of the electric furnace, which is not preferable because the upper lid itself is prematurely worn.

Further, although tap water or the like which is usually obtained can be used as the cooling liquid 11 as it is, the cooling liquid 11 can also be sprayed by mixing an anti-oxidizing agent such as calcium phosphate in the cooling liquid 11. If the antioxidant is mixed in this way, the antioxidant in the cooling liquid will be absorbed by the upper graphite electrode during spraying.
The outer peripheral surface of 10 is solidified and adhered to form an oxidation resistant film, so that oxidation consumption from the outer peripheral surface can be prevented more effectively. Thus, when the upper graphite electrode having the antioxidizing agent attached to the outer peripheral surface is used as the lower graphite electrode, the oxidation consumption from the outer peripheral surface is more effectively suppressed, and the electrode unit consumption is further improved. In order to achieve such an effect, it is necessary to add an antioxidant to 1 to 15
It is preferable to add about wt%.

Further, when the cooling liquid is sprayed with an upward inclination, it is preferable that the tip nozzle of the spray nozzle is configured so that the cooling liquid 11 hits the outer peripheral surface 10a of the graphite electrode 10 on average. As a preferable example of this, the tip nozzle is configured to be sprayed so that the cooling liquid 11 has a fan-shaped shape that spreads out. Furthermore, a filter is provided in a part of the spraying nozzle to remove dust in the cooling liquid 11. It is preferable that the foreign matter can be removed. Further, as shown in FIG. 1, even when the cooling liquid 11 is sprayed while inclining upward, as in the above case, each injection hole 16
It is preferable that a is configured or arranged such that the cooling liquid 11 hits the graphite electrode outer peripheral surface 10a on average.

Further, the cooling pipe 16 is configured symmetrically with the notch as the center, but the notch can be provided at any part.

Example 1 A cooling liquid 11 was looped downward to form a graphite electrode outer peripheral surface 10a.
When it was sprayed on and cooled, and the improvement effect was obtained as compared with the conventional example, it was as shown in Table 1.

In this case, Test Nos. 1 and 3 used an upper lid made of a magnesia-based refractory, while Test No. 2 used an upper lid made of an alumina-based refractory.

Also, in this operation, the unit charge was performed in about 2 hours as usual, and in this operation, the life of the upper lid of the alumina refractory was about 150 charges. 45 from charge to 600 charge
It spread like a 0 charge.

<Effects of the Invention> As described in detail above, the present invention provides a method for melting and refining a metal by directly spraying a cooling liquid to cool the outer peripheral surface of graphite electrodes sequentially connected through a nipple. This cooling liquid is jetted at an upward inclination angle of 10 to 35 ° with respect to the horizontal level, which is looped and sprayed onto the outer peripheral surface of the graphite electrode. Therefore, the cooling liquid hits the outer peripheral surface of the graphite electrode in a state where the jet energy is largely lost, and descends along the outer peripheral surface without being scattered to the surroundings. Is cooled over. The cooling fluid loops and contacts the graphite electrode,
The cooling liquid can form a cooling liquid film or the like without being scattered to the outside. Therefore, the electrode holder and the upper lid are not damaged or worn, and the life is improved even if the upper lid is a magnesia refractory material.

Also, while cooling by directly spraying the cooling liquid in this way,
Refining can greatly reduce the unit consumption of graphite electrodes in general metal refining as well as steelmaking.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of the method of the present invention, and FIG. 2 is a perspective view of a cooling device according to a conventional example. Reference numeral 1 ... furnace lid 2 ... graphite electrode 3 ... electrode holder 4 ... annular cooling pipe 5 ... vertical pipe 6 ... nozzle 7 ... graphite electrode 10a ... graphite electrode outer peripheral surface 11 ... cooling liquid 15 …… Furnace cover 16 …… Cooling pipe 16a …… Injection hole

Claims (2)

[Claims] 1. When melting and refining a metal by spraying and cooling a cooling liquid on the outer peripheral surface of graphite electrodes sequentially connected through a nipple, the cooling liquid is kept at a horizontal level of 10%.
A method for melting and refining a metal, characterized in that the sprayed liquid is sprayed at an upward inclination angle of ˜35 °, and the sprayed cooling liquid is looped and sprayed onto the outer peripheral surface of the graphite electrode. 2. An annular cooling pipe which surrounds the outer periphery of the graphite electrode and through which a cooling liquid flows is disposed between the furnace lid of the arc electric furnace and an electrode holder which holds the upper end of the graphite electrode. In an electrode cooling device used for melting and refining a metal sprayed with the cooling liquid from an inner peripheral surface of the annular cooling tube facing the outer peripheral surface of the graphite electrode, at least one location of the annular cooling tube is cut out to form a notch. At least one injection hole configured to inject the cooling liquid in the inner peripheral surface of the annular cooling pipe, inclining upward by 10 to 35 ° with respect to a horizontal level, and directing in the central axis direction of the graphite electrode. An electrode cooling device provided at the time of melting and refining a metal, characterized by being provided with.