JP2002121611A - Melting method and melting equipment for cold iron source - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To use an arc melting equipment having a preheating chamber directly connected to a melting chamber, and to maintain a state in which a cold iron source is continuously present in the preheating chamber and the melting chamber while maintaining a state of cold iron in the melting chamber. When the source is melted and hot water is supplied, the supply of the cold iron source from the preheating chamber to the melting chamber is stably performed. SOLUTION: The melting equipment 1 according to the present invention includes a melting chamber 2.
The shaft-type preheating chamber 3, which is directly connected to the upper part of the melting chamber and preheats the cold iron source 16 with the exhaust gas generated in the melting chamber, the electrodes 6 and 7 for arc generation, and the cold iron source melts with the preheating chamber. A cold iron source supply means 15 for supplying a cold iron source to the preheating chamber so as to be continuously present in the chamber; and a movable inside and outside of the preheating chamber, and at least one pusher is on standby when another pusher is present in the preheating chamber. A plurality of pushers 12 operated so as to be present at a position, and a tap 13 for discharging a molten metal 17, a cold iron source is melted by an arc 19, and a predetermined amount of molten metal is accumulated in a melting chamber. The hot water is discharged in a state where a cold iron source is present in the melting chamber and the preheating chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a melting method and a melting apparatus for efficiently dissolving a cold iron source such as iron scrap and direct reduced iron.

[0002]

2. Description of the Related Art In an arc melting apparatus for steelmaking, a cold iron source such as iron scrap or directly reduced iron is heated and melted by arc heat generated from an arc generating electrode, and refined to produce molten steel. A method of preheating a cold iron source using high-temperature exhaust gas generated from the melting chamber of an arc melting facility during melting to reduce power consumption by melting the preheated cold iron source Many have been proposed.

For example, Japanese Patent Publication No. 6-46145 (hereinafter referred to as "prior art 1") has a shaft-type preheating chamber directly connected to a melting chamber, and a cooling chamber for one heat is provided between the melting chamber and the preheating chamber. An equipment is disclosed in which an iron source is charged for each melting, and the cold iron source is melted while being preheated by exhaust gas. In the prior art 1, since the preheating chamber is directly connected to the melting chamber, equipment for holding and transporting the cold iron source is not required. Therefore, the temperature of the exhaust gas is raised without concern about equipment trouble due to heat of these equipment, Since the preheating temperature of the cold iron source can be raised, the power saving effect is excellent, but every time the amount of molten steel for one heat is melted, all the cold iron sources in the preheating chamber are melted and hot water is supplied, so the next heat It is not possible to preheat the cold iron source that is first melted, and it is not sufficient in terms of effective use of exhaust gas.

To solve this problem, Japanese Patent Application Laid-Open No. H11-25 / 1999
No. 7859 (hereinafter referred to as “prior art 2”) has been proposed by the present inventors. The melting method according to Prior Art 2 uses an arc melting facility including a melting chamber, a shaft-type preheating chamber directly connected to an upper part thereof, and a pusher provided at a lower part of the preheating chamber, and a cold iron source is provided with the preheating chamber. While supplying the cold iron source to the preheating chamber so as to keep the state continuously present with the melting chamber, the pusher enters and exits the preheating chamber to supply the cold iron source in the preheating chamber to the melting chamber, This is a melting method in which a cold iron source is melted by an arc, and when a predetermined amount of molten steel is accumulated in a melting chamber, the molten steel is discharged while the cold iron source is continuously present in a preheating chamber and a melting chamber. According to this melting method, a cold iron source is always present in the preheating chamber and the melting chamber, and in the second and subsequent heats, all the cold iron sources to be melted are preheated by the exhaust gas generated in the melting chamber, and the electric power consumption is reduced. Significant reductions are achieved.

[0005]

However, prior art 2 also has the following problems. That is, in Prior Art 2,
A pusher is provided to enter and exit the preheating chamber filled with the cold iron source, and by operating this pusher, the cold iron source in the preheating chamber is supplied to the melting chamber. If a space is created by the operation of the pusher in the cold iron source packed bed of the preheating room, the cold iron source cannot be pushed even if the pusher is operated thereafter, and the cold iron source must be supplied stably. Can not.

When the cold iron source in the preheating chamber in front of the pusher is not stretched even when pushed by the pusher due to the filling degree of the packed bed and the shape of the cold iron source, the cold iron source is surrounded. A strong force is applied to the facilities such as the preheating chamber side walls, which causes damage to these facilities. On the other hand, if the strength of the equipment is sufficiently strong, the equipment will not be damaged, but the cold iron source pushed by the pusher will be more densely filled than before the push, and the cold iron source This will have a negative effect on stable supply.

As described above, when the cold iron source filled in the preheating chamber is supplied to the melting chamber by being pushed by the pusher that moves in and out of the preheating chamber, there are optimal equipment specifications of the pusher and a method of operating the pusher. Although it does not mean that it is only necessary to press on the dark cloud, Prior Art 2 does not disclose anything about this point.

[0008] The present invention has been made in view of the above circumstances,
The purpose is to use an arc melting equipment having a shaft-type preheating chamber directly connected to the upper part of the melting chamber, and to cool the cold iron source so as to maintain a continuous state in the preheating chamber and the melting chamber. While supplying the iron source to the preheating chamber, the pusher enters and exits the preheating chamber to supply the cold iron source in the preheating chamber to the melting chamber while melting the cold iron source in the melting chamber to supply hot water. An object of the present invention is to provide a method and a facility for dissolving a cold iron source capable of stably supplying a source to a dissolution chamber.

[0009]

According to a first aspect of the present invention, there is provided a method for melting a cold iron source, comprising: a melting chamber; a shaft-type preheating chamber which is directly connected to the melting chamber and into which exhaust gas generated in the melting chamber is introduced; A method for melting a cold iron source in an arc melting facility equipped with a plurality of pushers moving in and out of a room, wherein the cold iron source is kept in a state where the cold iron source is continuously present in the preheating chamber and the melting chamber. A source is continuously or intermittently supplied to the preheating chamber, and at least one of the plurality of pushers is provided with a plurality of pushers so as to be at the standby position when another pusher is present in the preheating chamber. While operating, supplying the cold iron source in the preheating chamber to the melting chamber, the cold iron source in the melting chamber is melted by an arc, and when a predetermined amount of molten metal is accumulated in the melting chamber, the cold iron source melts with the preheating chamber. Discharges molten metal in a state that exists continuously with the chamber It is characterized in that.

According to a second aspect of the present invention, in the method for melting a cold iron source according to the first aspect, when a predetermined amount of molten metal has accumulated in the melting chamber, a plurality of pushers are stopped and the molten metal is heated by an arc. Then, the molten metal is discharged while the cold iron source is continuously present in the preheating chamber and the melting chamber.

According to a third aspect of the present invention, in the method for melting a cold iron source according to the second aspect, after the plurality of pushers are stopped, the melting chamber is tilted to reduce the contact area between the molten metal and the cold iron source in the melting chamber. Then, the molten metal is heated by an arc in a state where the melting chamber is tilted and the temperature is raised, and thereafter, the molten metal is discharged while the cold iron source is continuously present in the preheating chamber and the melting chamber. Things.

According to a fourth aspect of the present invention, there is provided a method for melting a cold iron source according to any one of the first to third aspects, wherein a pressure applied to the plurality of pushers when the cold iron source is pressed is set in advance. It is characterized in that it is made to retreat when it reaches the set value.

According to a fifth aspect of the present invention, there is provided a cold iron melting apparatus for melting a cold iron source, which is directly connected to an upper portion of the melting chamber, and preheats the cold iron source with exhaust gas generated in the melting chamber. A shaft-type preheating chamber, an electrode for arc generation for melting the cold iron source in the melting chamber, and a continuous cold iron source so that the cold iron source is continuously present in the preheating chamber and the melting chamber A cold iron source supply means for supplying the preheating chamber to the preheating chamber, either intermittently or intermittently, and at least one pusher is operated so as to be at the standby position when another pusher is present in the preheating chamber. Equipped with a plurality of pushers and a tap for discharging the molten metal, the cold iron source in the melting chamber is melted by an arc, and when a predetermined amount of the molten metal is accumulated in the melting chamber, it is cooled into the melting chamber and the preheating chamber. The feature is that the molten metal is poured in the presence of an iron source. Is shall.

According to a sixth aspect of the present invention, in the melting apparatus for a cold iron source according to the fifth aspect, the plurality of pushers can set an upper limit value of a pressure received when the cold iron source is pressed. When it reaches the value, it retreats.

In the present invention, a plurality of pushers are installed in a shaft type preheating chamber directly connected to the upper part of the melting chamber,
Of the plurality of pushers, at least one pusher operates the plurality of pushers such that the other pushers are in the standby position when the other pushers are present in the preheating chamber. Therefore, even if a space is created due to the pusher entering a certain part of the preheating chamber, there is no space in the front preheating chamber of the pusher that was present at the standby position at that time, so that the space exists at the standby position. The cold iron source can be pushed into the melting chamber by the pusher entering the preheating chamber, and the supply of the cold iron source to the melting chamber can be stabilized. In this case, even if a space is created in a certain part in the preheating chamber due to the entry of the pusher, the state of filling of the cold iron source is changed by allowing another pusher such as the pusher existing at the standby position to enter the preheating chamber. Therefore, the space in the preheating chamber is immediately canceled. As a result, the supply amount of the cold iron source into the molten metal is stabilized, and the melting time and the molten metal temperature are made uniform. Here, the standby position of the pusher is a position where the pusher is retracted to the maximum from the preheating chamber.

Here, the pusher can enter and exit the preheating chamber. When the pusher exits the preheating chamber, only the tip of the pusher is heated by the exhaust gas, and most of the pusher is not heated. The load is low, so that the preheating temperature of the cold iron source can be raised.

Further, the cold iron source in the melting chamber is melted while the supply of the cold iron source to the preheating chamber is continued so as to keep the state of the cold iron source continuously in the preheating chamber and the melting chamber, and Since the molten metal is discharged in a state where the cold iron source is continuously present in the preheating chamber and the melting chamber, all the cold iron sources to be used for the next heating are preheated and can be melted with extremely high preheating efficiency.

On the other hand, if the unmelted cold iron source is buried and coexists in the molten metal generated in the melting chamber, the applied thermal energy is used for latent heat for melting the cold iron source, and the molten metal temperature Is difficult to rise. However, in the second invention, the operation of the pusher is stopped when a predetermined amount of molten metal has accumulated, and the supply of the cold iron source to the molten metal in the melting chamber is suppressed to heat the molten metal. By stopping the pusher, the supply amount of the cold iron source into the molten metal is reduced, and the contact area between the molten metal and the cold iron source is relatively reduced. The amount consumed is reduced and the melt temperature can be raised. Therefore, it is possible to prevent a trouble due to a decrease in the temperature of the molten metal such as a blockage of a tap hole during tapping. At this time, by tilting the melting chamber together with the stoppage of the operation of the pusher, the contact area between the molten metal and the cold iron source in the melting chamber is further reduced, and the temperature of the molten metal can be increased more quickly.

When the pusher enters the preheating chamber,
An upper limit value of the pressure received from the cold iron source to be filled is set, and when this upper limit value is reached, it retreats from the preheating chamber and does not push the cold iron source more than necessary. Excessive pressure does not act on the equipment such as the surrounding preheating chamber side wall, and damage to these equipment due to operation of the pusher can be prevented beforehand.

In the present invention, the predetermined amount of molten metal is defined as
For example, when the amount of molten metal for one heat or the amount of molten metal remaining in the melting chamber after tapping is the sum of the amount of molten metal for one heat and the amount of residual molten metal in the melting chamber, the amount is appropriately determined according to the operating conditions. It is the amount of molten metal.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic longitudinal sectional view of an arc melting facility showing an example of an embodiment of the present invention, and FIG. 2 is a schematic plan view of the arc melting facility shown in FIG.

1 and 2, a shaft-type preheating chamber 3 and a side wall 4 of a water-cooling structure are disposed above a melting chamber 2 having a refractory inside and a bottom electrode 6 at the bottom. The upper opening of the side wall 4 has a water-cooled lid 5 which can be freely opened and closed.
Covered with. An upper electrode 7 made of graphite is provided that penetrates through the lid 5 and can move up and down into the melting chamber 2. The bottom electrode 6 and the upper electrode 7, which are electrodes for arc generation, are connected to a DC power supply (not shown), and the bottom electrode 6 and the upper electrode 7 are connected to each other.
And an arc 19 is generated. The melting chamber 2 is tilted in the direction toward the tap 13 by a tilting device (not shown).

Above the preheating chamber 3, a supply bucket 15 of a bottom open type suspended from a traveling carriage 24 is provided as a cold iron source supply means.
Opening / closing lid 20 provided on the upper part of the preheating chamber 3 and the opening / closing lid 20
By opening and closing a, a cold iron source 16 such as iron scrap or direct reduced iron is charged into the preheating chamber 3. When the cold iron source 16 is charged, the opening / closing lid 20 and the opening / closing lid 20a are alternately opened / closed, that is, one of the opening / closing lids 20 and 20a is closed, thereby generating the gas in the melting chamber 2. Exhaust gas leakage can be prevented. Further, a duct 21 provided at the upper end of the preheating chamber 3 is connected to a dust collector (not shown), and high-temperature exhaust gas generated in the melting chamber 2 is sucked through the preheating chamber 3 and the duct 21 in this order. The cold iron source 16 in 3 is preheated.

A hydraulic cylinder 11 is provided below the preheating chamber 3.
Pushers 12 connected to the system (three in FIG. 2)
Each pusher 12 is provided side by side in the horizontal direction.
Is moved into and out of the preheating chamber 3 by being driven by the respective hydraulic cylinders 11 connected thereto, and the cold iron source 16 filled in the preheating chamber 3 is moved to a space in the melting chamber 2 where the cold iron source 16 is not filled. Press and supply. The hydraulic cylinder 11
The maximum pressure when the pusher 12 enters the preheating chamber 3 can be set. When a load equal to or higher than the set maximum pressure is applied when the pusher 12 enters, the pusher 1
2 is stopped and retreated outside the preheating chamber 3. This maximum pressure value can be changed as appropriate, and it is possible to cope with a case where the lot or type of the cold iron source 16 changes. In addition, pusher 12
Can be constantly monitored by a video camera or the like.

If the pusher 12 frequently enters and exits the preheating chamber 3, a large amount of cold iron source 16 is supplied to the melting chamber 2,
Further, when the pusher 12 is stopped, the cold iron source 16 is supplied by freely falling according to the amount melted in the melting chamber 2, but the cold iron source 16 is supplied to the molten metal 17 in the melting chamber 2. The amount is not stable, and a shelving state occurs in the preheating chamber 3 so that the supply stops.

An oxygen blowing lance 8 and a carbon material blowing lance 9 are provided which penetrate the lid 5 and can move up and down in the melting chamber 2, and oxygen is blown from the oxygen blowing lance 8.
Then, a carbon material such as coke, char, coal, charcoal, graphite or the like is blown into the melting chamber 2 from the carbon material blowing lance 9 using air, nitrogen gas or the like as a carrier gas.

Further, the protrusion 2a provided on a portion of the melting chamber 2 which is different from the side to which the preheating chamber 3 is directly connected is pressed against the bottom thereof by the door 22 at the outlet side to fill the inside with sand. Or on the tap hole 13 filled with mud agent and its side wall,
There is provided a slag port 14 in which the exit side is pressed by a door 23 and filled with filling sand or a mud agent. A burner 10 is attached to the lid 5 at a position corresponding to a position vertically above the tap hole 13. The burner 10 burns fossil fuels such as heavy oil, kerosene, pulverized coal, propane gas, and natural gas in the melting chamber 2 with air or oxygen or oxygen-enriched air. Thus, the DC arc melting equipment 1 is configured.

When melting the cold iron source 16 in the DC arc melting apparatus 1 configured as described above, first, the melting chamber 2 is placed in a horizontal state, and the cold iron source 16 is supplied from the supply bucket 15 into the preheating chamber 3. Supply. The cold iron source 16 supplied into the preheating chamber 3 is also charged into the melting chamber 2 and eventually fills the inside of the preheating chamber 3. In addition, in order to uniformly load the cold iron source 16 into the melting chamber 2, the cold iron source 16 can be loaded into the melting chamber 2 on the opposite side of the preheating chamber 3 by opening the lid 5. Next, the upper electrode 7 is moved up and down while supplying a direct current between the bottom electrode 6 and the top electrode 7, and an arc 19 is generated between the top electrode 7 and the bottom electrode 6 and the inserted cold iron source 16. . Then, the cold iron source 16 is melted by the generated arc heat, and the molten metal 17 is generated. With the generation of the molten metal 17, a flux such as quicklime or fluorite is charged into the melting chamber 2 to form a molten slag 18 on the molten metal 17, thereby preventing oxidation of the molten metal 17 and keeping the temperature of the molten metal 17 warm. . Molten slag 1
If the amount of 8 is too large, it can be discharged from the slag port 14 even during melting.

Since the amount of the cold iron source 16 in the melting chamber 2 decreases with the generation of the molten metal 17, the operation of the pusher 12 is started from the time when the molten metal 17 is generated in the melting chamber 2. The pusher 12 may be operated so as to reciprocate in the preheating chamber 3 in several minutes at intervals of several minutes, for example, once every three minutes, in the preheating chamber 3 one by one. As described above, when a plurality of pushers 12 are operated at the same time, a space in which the cold iron source 16 does not exist is formed in front of the pushers 12, and it is difficult to avoid this. Drive individually. However, if at least one pusher 12 is at the standby position, two or more pushers 12 may be operated simultaneously. Pusher 1
The cold iron source 16 charged into the preheating chamber 3 by the operation of 2 is forcibly pushed and supplied to the molten metal 17 side.

Further, since the amount of the cold iron source 16 in the preheating chamber 3 decreases with the generation of the molten metal 17, in order to compensate for this decrease,
The cold iron source 16 is supplied from the supply bucket 15 to the preheating chamber 3. The supply of the cold iron source 16 into the preheating chamber 3 is performed by the cold iron source 1.
6 is carried out continuously or intermittently so as to keep a state where it is present continuously in the preheating chamber 3 and the melting chamber 2. At that time, in order to increase the preheating efficiency, it is preferable that the amount of the cold iron source 16 continuously present in the preheating chamber 3 and the melting chamber 2 is always 50% or more of the cold iron source 16 for one heat. .

It is preferable that oxygen and a carbon material be blown into the molten metal 17 or the molten slag 18 from the oxygen blowing lance 8 and the carbon material blowing lance 9 from the time the molten metal 17 is formed. This amount of oxygen blown is 25 tons of the molten metal 17 staying in the melting chamber 2 from the start of melting to tapping.
It is preferably at least Nm ³ (hereinafter referred to as “Nm ³ / t”). The carbon material blown and dissolved in the molten metal 17 or the carbon material suspended in the molten slag 18 and the blown oxygen react with each other to generate combustion heat and act as an auxiliary heat source, thereby saving power consumption. At the same time, the reaction product CO gas forms the molten slag 18 to form an arc 19.
Is wrapped in the molten slag 18, so that the efficiency of heating the arc 19 increases. In addition, the cold iron source 16 in the preheating chamber 3 is efficiently preheated by a high-temperature CO gas generated in large quantities by blowing oxygen and carbon material, and CO ₂ gas generated by burning this CO gas. . The amount of carbon material to be blown is determined according to the amount of oxygen to be blown. That is, a carbon material is added in an amount equivalent to the chemical equivalent of the oxygen to be blown. If the carbon material is less than the oxygen to be blown, the molten metal 17 is excessively oxidized, which is not preferable.

In this way, the cold iron source 16 is melted, and when a predetermined amount of the molten metal 17 has accumulated in the melting chamber 2, refining such as decarburization is performed if necessary, and then the melting chamber 2 is tilted. Then, the molten metal 17 is discharged from the molten metal outlet 13 into a molten metal holding container (not shown). It is preferable that the molten metal 17 be heated by the burner 10 during the pouring of the molten metal in order to prevent the temperature of the molten metal from lowering. After tapping, the molten metal 17 is heated and refined in a ladle refining furnace or the like as necessary, and then cast by a continuous casting machine or the like. Molten 17
After the molten slag 18 is discharged, if necessary, the melting chamber 2 is returned to a horizontal position, or the melting chamber 2 is tilted such that the tap hole 13 side in the direction opposite to that at the time of tapping is upward, After filling the filling port or the slag port 14 with the filling sand or the mud agent, the melting chamber 2 is placed in a horizontal state and the melting is resumed. The next heat can start melting with the preheated cold iron source 16.

In this case, since a large amount of unmelted cold iron source 16 is buried and coexist in the molten metal 17, the temperature of the molten metal is about 1550 ° C., and it is difficult to obtain a large degree of superheating of the molten metal. . Therefore, when a predetermined amount of the molten metal 17 has accumulated in the melting chamber 2 in order to obtain a large degree of superheating of the molten metal,
The operation of the pusher 12 is stopped and all the pushers 12
Is desirably placed outside the preheating chamber 3, and the molten metal 17 is heated by the arc 19 to increase the temperature. By stopping the pusher 12, the amount of the cold iron source 16 supplied into the molten metal 17 is reduced, and at the same time, the amount of the cold iron source 16 supplied to the molten metal 17 is reduced, so that the cold iron source 16 is buried in the molten metal 17. By promoting the dissolution of the unmelted cold iron source 16, the amount of the cold iron source 16 buried and coexisting in the molten metal 17 decreases, and the contact area between the molten metal 17 and the cold iron source 16 decreases. As a result, the amount of heat consumed in the latent heat for melting the cold iron source 16 in the arc heat to be input is relatively reduced, and the amount of heat used to increase the temperature of the molten metal is increased to increase the temperature of the molten metal. As a result, it is possible to obtain a large degree of superheat of the molten metal, and as a result, it is possible to prevent troubles caused by a decrease in the temperature of the molten metal, such as blockage of the tap hole 13 during tapping. In addition, the pusher 12
At the time of heating the molten metal 17 after the stop, the use of the burner 10 is preferable because the amount of heat to be supplied increases and the rate of rise of the molten metal temperature increases.

After the pusher 12 is stopped, the tap 13 is turned off.
It is preferable that the melting chamber 2 is tilted so that the side thereof faces downward to positively reduce the amount of the cold iron source 16 buried in the molten metal 17. By heating the melting chamber 2 in a tilted state, the molten metal 1
The contact area between the iron 7 and the cold iron source 16 is further reduced, and the speed of increasing the temperature of the molten metal is increased, so that a large degree of superheat of the molten metal can be obtained. After heating and raising the temperature of the molten metal 17, refining such as decarburization is performed as necessary, and the molten metal is discharged from the tap 13 as described above. At the time of tapping, several to several tens of tons of molten metal 17 are required.
May be left in the melting chamber 2 to restart the melting of the next heat. By doing so, the initial dissolution is promoted, and the dissolution efficiency is further improved.

By dissolving the cold iron source 16 in this manner, the preheating temperature of the cold iron source 16 can be increased, and a part of the cold iron source 16 used in the first heat of the operation is used. Since the cold iron sources 16 that are not preheated but are melted by the subsequent heat are all preheated, the operation can be performed in an extremely high preheating efficiency state, and the power consumption can be greatly reduced. In addition, since the cold iron source 16 can be stably supplied to the melting chamber 2 by the operation of the plurality of pushers 12, stable operation can be performed without prolonging the melting time or excessively increasing the temperature of the molten metal. Can be. Furthermore, since the side wall and the like of the preheating chamber 3 are not subjected to excessive pressure by the pusher 12, the operation can be stably performed without damaging the equipment. Further, after melting, the molten metal 17 is heated and
By raising the temperature, the temperature of the molten metal at the time of tapping is ensured, and operation troubles due to a decrease in the temperature of the molten metal can be prevented.

In the above description, the case of the DC arc melting equipment 1 has been described. However, the present invention can be applied to the AC arc melting equipment without any trouble, and the preheating chamber 3 and the tap 13 in the melting chamber 2 can be applied. Is not limited to a position 180 ° opposite to the center of the melting chamber 2,
The position may be 0 degrees, and it goes without saying that differences in the arrangement of the pusher 12 and the structure of the bottom electrode 6 and the like do not hinder the present invention.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the DC arc melting equipment shown in FIG. 1 will be described below. In the arc melting equipment, the melting chamber has an outer diameter of 7.2 m and a height of 4 m, the preheating chamber has a maximum width of 3 m, a length of 5 m, and a height of 7 m, and the capacity of the melting chamber is 1 in terms of molten steel.
80 tons.

First, 150 tons of iron scrap were charged into the melting chamber and the preheating chamber, and were melted using a graphite upper electrode having a diameter of 30 inches with a power supply capacity of 750 V and 130 kA at the maximum. With the formation of molten steel, three pushers were set to 10
The chamber was alternately moved into and out of the preheating chamber at intervals of 3 minutes so as to reciprocate in seconds. In this case, the upper pressure limit of the hydraulic cylinder that activates the pusher is 100 kg for all hydraulic cylinders.
/ Cm ² , and when the pusher entered, when the pressure of the hydraulic cylinder exceeded 100 kg / cm ² , the entry of the pusher was stopped, and the pusher was retracted to the standby position. Also, with the production of molten steel, quicklime and fluorite are added to form a molten slag, and then oxygen is injected from an oxygen blowing lance to form a molten slag.
Coke was blown into the molten slag at 80 kg / min from a carbon material blowing lance at 00 Nm ³ / hr. By blowing oxygen and coke, the molten slag was formed and the tip of the upper electrode was buried in the molten slag. The voltage at this time was set to 550V.

When the iron scrap in the preheating chamber descends as it melts, the iron scrap is supplied to the preheating chamber by the supply bucket, and the melting is continued while maintaining the height of the iron scrap in the preheating chamber at a constant level. When 180 tons of molten steel had been produced, about 60 tons were left in the melting chamber, and 120 tons of molten steel for one heat was poured into the ladle. During tapping, the molten steel was heated by a heavy oil burner. The carbon concentration of the molten steel at the time of tapping was 0.1% by mass, and the temperature of the molten steel was 1550 ° C.
After the tapping, the tapping hole and the tapping port were filled with sand and the melting was resumed. When the molten steel amount reached 180 tons, tapping of 120 tons was repeated. The molten steel after tapping was refined in a ladle refining furnace, heated to 1620 ° C., and then cast by a continuous casting machine. The average power consumption of the ladle refining furnace was 60 kWh per ton of molten steel (hereinafter referred to as “kWh / t”).

As a result, the supply of the cold iron source into the melting chamber was stable, the stagnation of the melting did not occur, the time from hot water to hot water was 40 minutes on average, and the amount of oxygen blown was 33 Nm.
³ / t, coke injection rate is 26k per ton of molten steel
g, it was possible to dissolve at a power consumption of 210 kWh / t. The total amount of electric power used by the arc melting equipment and the ladle refining furnace was 270 kWh / t. In addition, there was no damage caused by the heat of the pusher, and stable operation was possible.

For comparison, in the arc melting apparatus shown in FIG. 1, without setting the upper limit of the pressure at the time of entry of the pusher, only one of the three pushers was operated at the center, and the other was operated. Operation (comparative example) in which the operating conditions were the same as in the example, and 120 tons of iron scrap were charged into the melting chamber and the preheating chamber for each heat, and the entire amount of the charged iron scrap was melted. The operation of raising the temperature and tapping 120 tons of molten steel (conventional example) was also performed. In the conventional example, the pusher was not operated, the amount of oxygen blown and the amount of coke blown were the same as in the above-described embodiment, and the power consumption of the ladle refining furnace in the conventional example was 30 kWh / t.

In the comparative example, a space was created in the cold iron source packed bed in front of the pusher, and the cold iron source could not be pushed even when the pusher was operated, and the phenomenon of melting stagnation occurred about twice in one heat. . In addition, the cold iron source in front of the pusher has a strong tension force, so that the cold iron source does not collapse even when pushed with the pusher. A phenomenon that lasted for more than one minute occurred about once in six heats. In the conventional example,
Despite the presence of space in the melting chamber in front of the iron scrap to be filled into the preheating chamber, iron scrap did not fall from the preheating chamber to the melting chamber, and the phenomenon of melting stagnation occurred once every six heats. .

FIG. 3 shows a comparison between the time from tapping to tapping and the frequency in the example and the comparative example. As shown in FIG. 3, in the example of the present invention, the time from hot water to hot water was stable with little variation between heats, and was 40 minutes on average. On the other hand, in the comparative example, there was variation between the heats in the time from hot water to hot water, and in the heat in which the dissolution was stagnant, the time from hot water to hot water required 50 minutes, and the average value was 43 minutes.

In the comparative example, the electric power consumption in the arc melting equipment is 220 kWh / t, and the total electric power consumption in the arc melting equipment and the ladle refining furnace is 280 kWh / t. The unit power consumption of the equipment was 300 kWh / t, and the total amount of electric power used in the arc melting equipment and the ladle refining furnace was 330 kWh / t.
As described above, in the present invention, the total used amount is 6 compared to the conventional example.
It was possible to reduce the unit power consumption of about 0 kWh / t.

[0045]

According to the present invention, the preheating temperature by the exhaust gas generated from the melting chamber can be increased, and most of the melting cold iron source can be preheated, so that the preheating efficiency is extremely high. The power consumption can be greatly reduced, the cold iron source can be stably supplied to the melting chamber by multiple pushers, and the load on the equipment due to the operation of the pushers is reduced. Therefore, the melting time is prolonged and the temperature of the molten metal is excessively increased, and
It can be stably dissolved without causing equipment damage, and an industrially beneficial effect is brought about.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of an arc melting facility showing an example of an embodiment of the present invention.

FIG. 2 is a schematic plan view of the arc melting equipment shown in FIG.

FIG. 3 is a diagram showing a comparison between the time from tapping to tapping and the frequency in the example according to the present invention and a comparative example.

[Explanation of symbols]

 Reference Signs List 1 DC arc melting equipment 2 Melting chamber 3 Preheating chamber 6 Bottom electrode 7 Upper electrode 11 Hydraulic cylinder 12 Pusher 13 Tap 15 Supply bucket 16 Cold iron source 17 Melt 18 Melting slag 19 Arc

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideaki Mizukami 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Noboru Suyama 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Sun Inside the Kokan Co., Ltd. (72) Inventor Yasuhiro Sato 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. F-term (reference) 4K014 CB01 CB02 CB07 CC00 CD13 CD14 4K045 AA04 BA02 DA01 RB02 RC02 4K055 AA03 DA03 4K063 AA04 AA12 BA02 CA01 CA06 GA02 GA09

Claims (6)

[Claims] 1. An arc melting apparatus including a melting chamber, a shaft-type preheating chamber directly connected to the melting chamber, into which exhaust gas generated in the melting chamber is introduced, and a plurality of pushers that enter and exit the preheating chamber. A method for melting a cold iron source, wherein the cold iron source is continuously or intermittently supplied to the preheating chamber so as to maintain a state where the cold iron source is continuously present in the preheating chamber and the melting chamber. At least one of the pushers operates a plurality of pushers so as to be at the standby position when another pusher is present in the preheating chamber and supplies a cold iron source in the preheating chamber to the melting chamber, It is characterized by melting the cold iron source in the melting chamber with an arc, and discharging the molten metal in a state where the cold iron source is continuously present in the preheating chamber and the melting chamber when a predetermined amount of molten metal has accumulated in the melting chamber. Dissolution method of cold iron source. 2. The method for melting a cold iron source according to claim 1, wherein when a predetermined amount of molten metal has accumulated in the melting chamber, a plurality of pushers are stopped and the molten metal is heated by an arc to raise the temperature. And then discharging the molten metal in a state where the cold iron source is continuously present in the preheating chamber and the melting chamber. 3. The method of melting a cold iron source according to claim 2, wherein after the plurality of pushers are stopped, the melting chamber is tilted to reduce the contact area between the molten metal and the cold iron source in the melting chamber. The molten metal is heated by an arc while the chamber is tilted, and the temperature is raised.
Thereafter, the molten iron is discharged while the cold iron source is continuously present in the preheating chamber and the melting chamber. 4. The apparatus according to claim 1, wherein the plurality of pushers are retracted when the pressure received when the cold iron source is pressed reaches a preset value. The method for dissolving a cold iron source according to any one of the first to third aspects. 5. A melting chamber for melting a cold iron source, a shaft-type preheating chamber directly connected to an upper part of the melting chamber and preheating the cold iron source with exhaust gas generated in the melting chamber, and a cooling chamber in the melting chamber. An electrode for arc generation for melting the iron source, and a cold supply for supplying the cold iron source to the preheating chamber continuously or intermittently so as to keep the cold iron source continuously present in the preheating chamber and the melting chamber. An iron source supply means, a plurality of pushers operated to be in a standby position when another pusher is present in the preheating chamber, and a plurality of pushers operating at a standby position when another pusher is present in the preheating chamber; The molten iron source in the melting chamber is melted by an arc, and when a predetermined amount of molten metal has accumulated in the melting chamber, the molten metal is discharged in a state where the cold iron source is present in the melting chamber and the preheating chamber. A melting facility for a cold iron source. 6. The plurality of pushers can set an upper limit value of a pressure received when a cold iron source is pressed, and retreat when reaching the upper limit value.
A melting facility for a cold iron source as described in the above.