JP3263928B2 - Continuous heating melting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat melting method capable of continuously melting a material to be melted such as a metal or ore to continuously obtain a molten metal at a desired temperature.

[0002]

2. Description of the Related Art As an apparatus for melting cast iron, cupolas and crucible-type induction furnaces are well known and widely used. Cupola is a continuous melting furnace in which high-quality refined molten metal (hereinafter, abbreviated as molten metal) is continuously obtained, and an induction furnace is an intermittent melting furnace in which fine materials can be used and components can be easily adjusted. These have advantages and disadvantages, respectively. At present, the double dissolution method using both of them has been widely used.

[0003] Japanese Patent Publication No. 52-48564 discloses a technique related to this kind of technology.

[0004]

Cupola requires a large amount of air to be blown into the furnace in order to burn coke at a high temperature. Therefore, the gas flow rate in the furnace is large. For example, fine materials such as pig iron Before being oxidized or melted, it is difficult to dissolve because it is discharged out of the melting device by the gas flow. Further, since the heat source for heating and melting the material is caused by the combustion of coke, a high temperature is accompanied by incomplete combustion. In particular, in order to obtain a tapping temperature of 1,500 ° C. or higher, the efficiency is lowered and the temperature control is difficult.

[0005] On the other hand, the induction furnace melts only by mere induction heating of the material, so that no refining effect can be expected. In addition, there is a problem that it is basically an intermittent melting method and it is inconvenient to supply molten metal to a continuous casting apparatus.

Further, Japanese Patent Publication No. Sho 52-4 mentioned in the prior art
In Japanese Patent No. 8564, an induction coil is installed above a cupola to heat a material. However, heating of a coke layer is not considered at all, and thus disadvantageousness for blowing a large amount of air and high temperature can be efficiently obtained. The measures for this have not been improved.

That is, the above-mentioned conventional melting method using both an induction furnace and a combustion furnace is a proposal for a continuous melting technique in which electromagnetic induction heating is used for heating a low-temperature part and combustion heating using coke is used for heating a high-temperature part. However, it has not reached the practical level.

That is, in this kind of prior art,
Induction heating is used in the low-temperature part heating of the upper part of the furnace where the molten material is charged, but it is used as so-called pre-heating means for induction heating only the metallic material that is the flowing material to be melted, and it uses electric power. Preheating is economically expensive and impractical. In addition, the heating of the high-temperature section located in the lower part of the furnace is a combustion method using coke, so the efficiency is reduced due to CO generation due to incomplete combustion of coke, the equipment is enlarged due to the generation of a large amount of exhaust gas, and measures to prevent pollution are taken. Need,
The point that the material to be melted is scattered by the gas flow and becomes difficult to dissolve,
Further, there is a problem that the metal is oxidized by oxygen in the gas with the combustion, sufficient reduction does not proceed, and the oxide becomes slag.

Accordingly, an object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to use a fine material such as pig iron and to provide a high-quality material having a small content of gas such as oxygen and nitrogen. It is an object of the present invention to provide an improved method for dissolving a molten metal by electromagnetic induction heating, wherein the temperature is continuously and stably adjusted.

In order to achieve the above object, a continuous heating and melting method according to the present invention provides a carbon material and a conductive material on a bottom of a furnace provided with a tap hole at the bottom of the furnace and an inlet for material to be melted at the top. By laminating at least one material of a refractory having a property as a heating medium and supplying power to an electromagnetic coil provided on the outer periphery of the furnace wall, the laminated heating medium is heated by electromagnetic induction heating and heated. A method for continuously heating and melting a material to be melted by continuously charging the material to be melted onto the heating medium, and melting the material to be melted, and flowing out the molten metal from a tap hole. In (1) the melting of the electromagnetic coil wound around the outer periphery of the furnace wall at a predetermined height
In the furnace, a heating medium lower than the height of the electromagnetic coil
Laminate from the lower part of the furnace and heat it in advance by electromagnetic induction heating
A step that, (2) the power supplied to the electromagnetic coil is set to a constant value
In the state of being heated, the induction heating amount of 20
About 50%, and the remaining 80-50% to the material to be melted.
Put the material to be melted into the furnace so that
Laminate the desired temperature based on the lamination thickness of the heating medium
So that the voltage generated in the electromagnetic coil is
Or setting the impedance as a reference value in advance
If, (3) the melting material of the object to be dissolved material dissolved furnace is reduced
Voltage or impedance generated in the electromagnetic coil
The variation of the sensing is compared with the preset reference value and detected.
Output and fluctuation of the detected voltage or impedance
Re-introducing the material to be melted into the furnace so as to compensate for the
And a floor .

Preferably, a voltage corresponding to the electric power is received, and when the voltage is higher than a reference voltage, the material to be melted is charged into the furnace when the voltage is higher, and when the voltage is lower, the charging is stopped. To control the temperature of the molten metal flowing out of the tap hole to a predetermined temperature.

More specifically, a tap hole is provided at the bottom of the furnace, and at least one of a carbon material and a conductive refractory is placed on the bottom of the furnace where a material to be melted is provided at the top. By laminating as a heating medium and supplying power to an electromagnetic coil provided on the outer periphery of the furnace wall, the laminated heating medium is heated by electromagnetic induction heating, and the material to be melted is heated on the heated heating medium. A method of continuously heating and melting a material to be melted by continuously charging and melting the material to be melted and continuously flowing out the molten metal from a tap hole. In the electromagnetic induction heating, the method is to supply the material to an electromagnetic coil. The power is controlled to be constant by the power control device on the power supply side, and the ratio of the amount of heat generated by the heating medium and the material to be melted is set to a constant value in advance, and the ratio fluctuates as the material to be melted melts. Electromagnetic Compensating for the change in impedance of the coil by changing either the voltage or the current applied to the electromagnetic coil, receiving a voltage corresponding to the power, and comparing the voltage with a reference voltage if the voltage is higher than the reference voltage. It is characterized in that the material to be melted is charged into the inside, and when it is small, the charging amount is controlled so as to stop the charging, whereby the temperature of the molten metal flowing out of the tap hole is adjusted to a predetermined temperature.

When monitoring the voltage and weighing a plurality of types of materials to be melted in predetermined amounts from the material inlet, and putting them into the furnace, the respective weighing data of the plurality of types of material to be melted are measured. Is received, the weighing data is integrated by the arithmetic unit, and it is determined whether or not the blending ratio of the integrated amounts is within a predetermined range. Is to control the operation of taking out the material to be melted so as to stop the work of taking out the material to be melted when the value exceeds.

[0014] More preferably, before the material to be melted is put on the laminated material (heating medium), the laminated heating medium is preheated. Before charging on the medium, the lower part of the laminated heating medium is heated by sucking the gas inside the furnace from the tap hole, and when the upper part of the heating medium reaches the melting temperature of the material to be melted, the tap port is turned on. By closing and closing the metal material in an amount not exceeding the weight of the heating medium and dissolving it, opening the tap hole a predetermined time after the introduction of the metal material, and pouring the material to be melted onto the heating medium. is there.

The electromagnetic induction heating is performed by applying high-frequency energy to an electromagnetic coil mounted on the outer wall of the furnace. Commonly used high frequency energy has a frequency of 5
100 to 5,000 Hz and output of 100 to 10,000
00 kW.

A preferable calorific value distribution by the typical electromagnetic induction heating is that the calorific value of the heating medium laminated on the furnace bottom is 20 mm.
５０50%, and the calorific value of the material to be melted put thereon is the remaining 80 ％ 50%. With this, it is 1,
It is possible to continuously obtain molten cast iron at 400 to 1,600 ° C.

The material laminated on the bottom of the furnace as a heating medium is as follows:
Preferably, it is coke, for example, 3,000 to 10,
One having a specific resistance of 000 μΩcm is used.
Further, as the material to be melted, for example, fine metal materials such as scrap, press waste, and pig iron which are usually called scrap iron are used. Fine materials such as pig iron can be used alone, but usually a mixture of scrap and press waste, for example, 20 to 60% is used.

[0018]

The carbon material used as a heating medium or a conductive refractory has a higher electrical resistance than a metal. For example, coke having a specific resistance of about 5,000 μΩcm can be sufficiently heated by high-frequency induction heating. By applying a part of the induction heating amount for melting the material to be melted, for example, the metal to the coke filled in the furnace bottom, the coke can be removed in an atmosphere where no air is present, and thus without using combustion. As a heating medium, it can be heated to a temperature necessary for melting the metal.

In this method, unlike the combustion method, a high-temperature atmosphere in which oxygen and nitrogen hardly exist can be created, and the temperature can be controlled by changing the ratio of the amount of heating applied to the coke.

Specifically, by maintaining a constant ratio between the amount of coke and the amount of metal in the induction heating zone in the furnace, the ratio of the power absorbed by the coke and the metal is kept constant to affect the melting rate. And a constant temperature atmosphere can be obtained. For example, by giving 20 to 50% of the induction heating amount to the coke and giving the remaining 80 to 50% to the metal, the molten metal can be dropped and brought into contact with the atmosphere to perform heating and refining. Even if a material that is easily oxidized such as Dalai is used, it can be melted at a constant temperature with almost no slag.

Although any carbon material can be used, coke having a fixed resistance of less than 3,000 μΩcm is not only economically expensive and unsuitable, but also because of the progress of graphitization, a molten metal (for example, cast iron) )) Is too much, and coke exceeding 10,000 μΩcm is difficult to heat, so that the specific resistance is 3,000-10,000.
It is preferable to use one of 000 μΩcm.

Further, the present invention is characterized in that preheating of the material can be continuously and efficiently performed because a continuous melting apparatus is used. In the electromagnetic induction heating of the present invention, if the ratio of the amount of induction heating to the carbon material portion serving as a heating medium is less than 20% of the total heating amount including the amount of heating by preheating, the heating amount after melting is reduced. The temperature of the molten metal to be discharged is 1,
If it is less than 400 ° C., it will be too low, and if it exceeds 50%, the amount of heating after melting will increase and exceed 1,600 ° C., causing overheating. Therefore, the tapping temperature is set to 1,400 to 1,60
When it is desired to set the temperature at 0 ° C., it is a practically preferable operating condition that the ratio of the amount of induction heating to the carbon material portion is in the range of 20 to 50% as described above.

Further, a power output 100 of high frequency energy
Below kW, over 5,000 Hz, the device becomes too small, and output over 10,000 kW, frequency 50
If it is less than 0 Hz, the device tends to be too large. Therefore, in the case of casting iron melting, the power output 100 to 1
It is desirable to perform the operation in a range of 0000 kW and a frequency of 500 to 5,000 Hz.

At the beginning of the operation, the tapping temperature tends to be low because the furnace is not sufficiently heated. In this case, the tapping hole is temporarily closed, and a metal material such as pig iron is charged in advance. The temperature can be raised by accumulating the molten metal in the furnace and induction heating the metal.

In the induction heating, connecting the high-frequency energy control means between the high-frequency energy applying means (power supply) and the induction heating electromagnetic coil is effective in stabilizing the output fluctuation. In other words, when the material to be melted is charged into the furnace, the impedance of the coil fluctuates depending on the material and the charging state. This variation is stably compensated for by the voltage or current fluctuation of the control means, and the output and the like are kept constant. Is what you do.

[0026]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows an entire configuration of a melting apparatus used for carrying out the continuous heating and melting method of the present invention, and FIG. 2 schematically shows a cross-sectional structure of an induction heating section. First, the overall configuration of the apparatus used will be described, and then an example of an actual continuous heating and melting method will be described.

(1) Configuration of Melting Apparatus The furnace 12 is composed of a substantially cylindrical refractory material 4 having an openable / closable tap hole 5 at a furnace bottom 13 and an inlet 11 to be melted provided at an upper portion thereof. Have been. The inner diameter of the refractory material 4 is 40
0 mm and height is 700 mm. Melted material inlet 11
Above is provided an annular preheating means 8 having a burner 14 using a general gas or liquid fuel.

A supply means 6 for supplying the material 2 to be melted into the material inlet 11 through the preheating means 8 is provided above the preheating means 8. The supply means 6 will be described later in detail with reference to FIGS.
On the outer periphery of the refractory material 4 of the furnace 12, the electromagnetic coil 3 is provided.
In the form of being wound around the axis of. Electric power is supplied to the electromagnetic coil 3 from a high-frequency energy applying means, that is, a power supply 9 via a power control device 110.

Control means 10 for controlling high-frequency energy is interposed between the power supply 9 and the material supply means 6. The control means 10 controls the material 2 to be melted
Is a high-frequency energy control means for compensating for the impedance fluctuation of the electromagnetic coil 3 caused by the melting of the coil by the voltage fluctuation.

The frequency of the high-frequency energy from the power supply 9 is 3,000 Hz, and the output is 175 kW. The molten metal flowing out of the tap hole 5 is supplied to a forehearth 7 having a capacity of 150 kg.
Received by

A carbon material 1 is laminated as a heating medium on a furnace bottom 13 inside the furnace 12, and a material to be melted 2 is supplied onto the carbon material 1 by a material supply means 6. The carbon material 1 is, for example, coke, and the specific resistance of the coke is 5,000 μΩcm. Material to be melted 2
Is a mixture containing a small amount of additives such as, for example, 4 parts of return scrap, 3 parts of pig iron, 3 parts of electrical steel sheet press waste, and iron silicide. The proportion of fine materials such as pig iron and pressed scraps of electrical steel sheet of the material 2
On the other hand, 0 to 100% can be used, but induction heating,
The use of 20 to 60% is preferable for shutting off the atmosphere in the furnace.

(2) One Example of Continuous Heating and Melting Method When starting the melting operation by the continuous heating and melting apparatus as described above, first, the thickness of the coke layer remaining in the furnace 12 after the previous operation is determined. About 250 from the furnace bottom 13
Adjust to mm. If it is less than 250 mm, supply new coke. The coke at this time has a total weight of about 30k
g, the number was about 100 pieces, and the maximum weight of one piece was 2 kg. After the completion of the coke charging, power is supplied from the power supply 9 to the electromagnetic coil 3.

The control means 10 has a function of compensating the impedance variation of the electromagnetic coil 3 by the voltage variation as described above. The large coke in the upper part of the coke layer efficiently absorbs power and generates heat, but the small coke in the lower part hardly generates heat, so the gas in the furnace is sucked from the tap hole 5, and the coke is Heating the lower part of the layer is effective.

The voltage at this time is 1,120 V, and the input is 82
kW. When the temperature of the upper part of the coke layer reaches about 1,600 ° C., the tap hole 5 is closed, 20 kg of pig iron as a metal material is charged and melted, and this is stored in the furnace bottom 13 and heated for a predetermined time. By this operation, the inside of the furnace 12 is rapidly heated, and a high-temperature molten metal is obtained from the start of the operation. At this time, the voltage was 1,130 V, and the input was 136 kW.

When the temperature of the molten pig iron reaches 1,500 ° C. or higher, the tap hole 5 is opened and the molten metal is introduced into the forehearth 7, and at the same time, the supply of the material 2 to be melted by the material supply means 6 is started.
When the material to be melted 2 is charged, the upper part of the coke layer is closed by the material to be melted, and only the tap hole 5 communicates with the outside. Since the tap hole 5 is also closed by the molten metal when the tapping is started, the flow of air into the furnace is substantially shut off.

The material 2 to be melted, particularly the massive return scrap is induced by the electromagnetic coil 3 and is lowered while the temperature rises. When it reaches the lowermost layer, it is also supplied with heat from the lower coke layer 1. Melts. The molten material 2 in the form of liquid droplets is further heated while being sewn and dropped between the cokes, and after being refined by a high-temperature coke and a reducing atmosphere in which oxygen is scarcely present, a pouring outlet. Hot water is supplied from 5.

Since the output is adjusted to be constant by the power supply 9, if the material 2 to be melted in the furnace 12 decreases and the impedance of the electromagnetic coil 3 increases, and the voltage exceeds 1,000 V (reference voltage), Controlled by the control means 10,
The material to be melted 2 is supplied into the furnace by the material supply means 6.

On the other hand, when the amount of the material 2 to be melted in the furnace increases, the impedance of the electromagnetic coil 3 decreases accordingly, and when the voltage falls below the reference voltage of 1,000 V, the material supply means 6 supplies the material 2 to be melted. It stops automatically, the output and voltage during operation are controlled to about 173 kW and 1,000 V, respectively, and continuous melting is maintained.

The tapping temperature in this steady state is about 1,4
It was 50 ° C. The time required to melt one ton of the material to be melted is 3.27 hours, and the electric energy is 566 kW by input.
h, the amount of coke replenishment was 11 kg, and the amount of slag generated could not be measured, but was extremely small, and damage to the refractory material 4 was very small. In this embodiment, the burner 14
Although the preheating means 8 provided with is not used, when it is used, power can be saved according to the amount of heating, and the tapping speed can be increased. Moreover, while the amount of power saving in a general crucible furnace is 20% or less, when the preliminary means 8 is used (using a heavy oil burner) in the present invention, the amount of power saving can be up to 30%.

Table 1 is a table showing the relationship between the thickness of the coke layer 1 and the input power when the thickness of the coke layer 1 laminated on the furnace bottom is changed and the coke layer 1 is heated at a reference voltage of 1,000 V. (The material to be melted is not supplied).

[0041]

[Table 1]

Table 2 shows that the material to be melted 2 was controlled so that the reference voltage was kept at 1,000 V and the input power was kept at 173 kW.
Layer when coke is supplied to the furnace and actually melted
It is a table which shows the relationship between the thickness of hot water and the tapping temperature.

[0043]

[Table 2]

As can be seen from Table 2, since the tapping temperature can be controlled to a predetermined temperature only by changing the thickness of the coke layer 1, as the melting progresses and the level of the material 2 to be melted in the furnace decreases, The continuous melting for obtaining the molten metal at a constant temperature can be maintained only by charging the material 2 to be melted.

In the actual operation, on the contrary, as described later, the thickness of the coke layer 1 is set to be constant, and the reference voltage is set so that a desired tapping temperature is obtained. A certain amount of the material 2 is automatically introduced from the material supply means 6 into the furnace so as to compensate only when the amount of the material 2 in the furnace is reduced and the voltage rises above a set value. As a result, continuous melting is maintained such that a molten metal at a constant temperature is always obtained from the tap hole 5.

Table 3 shows the results of analyzing the chill depth and the gas content of cast iron obtained by general cupola melting, crucible-type induction furnace melting, and the continuous heating melting method according to the present invention. At this time, the composition of the material to be melted 2 was steel scrap 3.
0%, and the components of the molten metal were measured under substantially the same conditions so as to contain 3.3% of carbon and 2.0% of silicon. As is well known, the quality of cast iron is better as the chill depth is shallower, and as the content of gas is smaller,
It will be clear from Table 3 how the method of the present invention is superior to other dissolution methods.

[0047]

[Table 3]

In the above description, the case where the cast iron is melted by using coke has been described. However, the present invention is not limited to coke, but instead of coke, a conductive refractory (for example, conductive ceramics) is used.
It is possible to dissolve other metals such as copper alloys and ores (preferably those having conductivity).

When it is desired to further reduce the evaporable impurities such as zinc and the like, it is also possible to provide a vent in the furnace and blow an inert gas or a reducing gas to actively promote the evaporation of the impurities. .

As is apparent from these examples, according to the present invention, the material to be dissolved is dissolved and heated in a reducing atmosphere in which the gas flow is small. The generation of slag based on slag is hardly recognized, and a high-quality molten metal having a low content of gas such as oxygen and nitrogen can be obtained.

As described above, referring to FIGS. 3 and 4, the structure and operation of the material supply means 6 (hereinafter simply referred to as supply means 6) for the material to be melted 2 and the high frequency energy applying means 9 will be described. The relationship with the control means 10 will be described in detail. FIG. 3 is a control system block diagram for explaining the operation of the supply means 6 for charging the material 2 to be melted into the furnace, and FIG. 4 is a perspective view showing the structure of the supply means 6.

As shown in FIG. 4, the supply means 6 includes a charging device 103 composed of a belt conveyor or a vibration conveyor. The feeding device 6 measures a required amount of the material 2 to be charged and measures the required amount of the material 2 to be charged. Into the furnace 12. That is, the supply means 6 exemplified here is the material hopper 201
The take-out means 200, which includes lifting magnets (200L, 200M, 200N) for picking up, for example, three kinds of the material 2 to be melted, and the three kinds of material 2 taken out of the hopper 201 by these take-out means are measured. Electronic balance 202 (202A, 202B, 202C) using a strain gauge for performing the measurement.

As shown in FIG. 3, the control means 10 includes a voltage comparison device 105 for judging the level of the voltage sent from the high-frequency energy applying means 9 and a reference voltage generation device for generating a reference voltage used for this judgment. 106 and each scale 202
And an arithmetic unit 107 for mixing the three types of materials to be melted in a predetermined ratio based on the weighing data from (202A, 202B, 202C).

The voltage comparator 105 has control lines (114, 115) for controlling the material take-out means (200L, 200M, 200N), respectively, and the voltage sent from the line 104 is higher than the reference voltage. If the value is high, a signal is output to the control line 115, and if the value is low, a signal is output to the control line 114.

The arithmetic unit 107 is connected to each scale 202 (202
A, 202B, 202C) via line 112 and each retrieval means 2 via line 113.
00 (200L, 200M, 200N).

The impedance of the electromagnetic coil 3 of the furnace 12 increases as the material 2 in the furnace 12 decreases,
Has the characteristic that the impedance decreases as the value increases. High-frequency power is supplied to the electromagnetic coil 3 from the high-frequency energy applying means 9 via the conductor 108. The high-frequency energy applying means 9 is provided with a power control device 110 for controlling the supplied power to be constant.

The high-frequency energy applying means 9 includes:
The voltage supplied to the electromagnetic coil 3 of the furnace 12 via the conductor 108 is converted into a corresponding low DC voltage, and the converted DC voltage is converted into a voltage comparison device 105 of the control means 10.
Is provided.

The operation of the block diagram shown in FIG. 3 will be specifically described as follows. As the melting proceeds and the material 2 to be melted in the furnace 12 decreases, the impedance of the electromagnetic coil 3 increases. Since the power control device 110 controls the power supplied to the electromagnetic coil 3 of the furnace 12 to be constant, when the impedance of the electromagnetic coil 3 increases, the electromagnetic coil 3
Is increased. This voltage is converted into a corresponding low DC voltage by the voltage converter 111 and supplied to the voltage comparator 105.

The voltage comparator 105 is supplied with a reference voltage from a reference voltage generator 106. Thus, when the voltage from the voltage converter 111 is higher than the reference voltage, a signal is output from the line 115 to each of the extracting means 200 (2).
00L, 200M, 200N), the respective take-out means 200 operate, and the work of taking out the material to be melted 2 is performed.

The take-out means 200 may be constituted by a moving device which applies vibration to the hopper of the material 2 to be melted and transfers the material 2 to the scales 202A to 202C instead of the lifting magnet. In this extraction, it is not always necessary to accurately extract a fixed amount. In the former case, it is only necessary to set a current value, and in the latter case, it is only necessary to set a vibration time for applying vibration to the hopper 201.

Thus, each material 2 to be melted taken out under certain conditions is individually controlled by the electronically controlled balance 202.
(202A, 202B, 202C), and each weighing data is sent to the arithmetic unit 107.

The arithmetic unit 107 stores a desired value of the mixing ratio of each melting material 2 to be charged into the furnace 12. Line 11
As long as the ratio of the integrated amount of the measurement data of each melting material 2 sent through the line 2 is within a certain range with respect to the desired value, the signal from the voltage comparator 105 via the line 115 As long as it comes out, each take-out means 200 (200
L, 200M, 200N) continue to operate. However, when the integrated amount of any of the three types of materials to be melted exceeds a certain range with respect to the desired value of the mixing ratio, the arithmetic unit 107
A signal is sent to the means 200 for removing the material to be melted 2 via the line 113 so as to stop the operation of removing the material to be melted 2 until the mixing ratio falls within a certain range with respect to the desired value. Each material to be melted 2 is supplied to the furnace 12 by the charging device 103 as soon as the weighing is completed.

When the amount of the material 2 to be melted in the furnace 12 increases,
The impedance of the electromagnetic coil 3 decreases,
Decreases, the voltage sent from the voltage converter 111 to the voltage comparator 105 via the line 104 decreases. When this voltage falls below the reference voltage,
The voltage comparison device 105 sends a signal to each of the extracting means 200 (200L, 200M, 200N) via the line 114 to stop the operation of each of the extracting means.

Since the apparatus of the present invention is operated as described above, the apparatus according to the present invention does not require weighing of each material to be melted by a weighing device at a time by a constant amount as in a cupola material feeding apparatus. It is possible to quickly and accurately supply each of the melted materials 2 to the furnace 12 simply by accurately weighing the melted material 2 taken out by each of the takeout means 200.

The weighing device 202 (202A, 202B, 2
02C) is, for example, an upper plate weigher equipped with a load cell, which includes means for converting weighing data into an electric signal and sending it out.

As described above, in the melting method of the present invention, the carbon material 1 is used as a heating element (heating medium) by electromagnetic induction heating.
Also acts as a reducing agent in refining. Therefore,
Unlike the heating and melting method using the conventional combustion method, the carbon material or the conductive refractory itself is not exposed to the combustion gas, so that the consumption amount is extremely small. In addition, since the combustion gas is not used for heating the carbon material or the conductive refractory, the electromagnetic induction heating is performed on the carbon material or the conductive refractory in a state where the flow of air in the furnace is substantially cut off. A favorable reducing atmosphere is achieved. As a result, it is possible to produce a high-quality molten metal having a small content of gas such as oxygen and nitrogen, and no special exhaust gas treatment equipment is required.

[0067]

As described in detail above, the intended object has been achieved by the present invention. In other words, it is possible to efficiently dissolve even fine materials such as pig iron, and to reduce oxides by refining the heated carbon material and reducing atmosphere. High quality metal with low gas content
Moreover, there is an effect that it can be obtained industrially.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main part of an entire configuration of a melting apparatus used for carrying out a melting method of the present invention.

FIG. 2 is a vertical sectional view of a main part showing details of the furnace.

FIG. 3 is a control system block diagram for explaining an operation of a supply unit of the material to be melted.

FIG. 4 is a perspective view showing a configuration of a supply unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Carbon material, 2 ... Material to be melted, 3 ... Electromagnetic coil, 4 ... Refractory material, 5 ... Tap hole, 6 ... Supply means, 7 ... Forehearth, 8 ... Preheating means, 9 ... High frequency energy applying means, 10 ... Control means, 11: melting material inlet, 12: furnace, 13: furnace bottom, 14: burner, 103: conveyor, 104, 108, 112, 113 ... line, 105: voltage comparison device, 106: reference voltage generation device Reference numeral 107: arithmetic unit 110: power control unit 111: voltage converter 114, 115: control line 200: material take-out means 201: hopper 202: electronic control balance

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI F27D 7/06 F27D 7/06 C

Claims (6)

(57) [Claims] 1. A furnace in which at least one of a carbon material and a conductive refractory is laminated as a heating medium on the bottom of a furnace having a tap hole provided at the bottom of the furnace and a material charging port at the top. Then, by supplying electric power to an electromagnetic coil provided on the outer periphery of the furnace wall, the laminated heating medium is heated by electromagnetic induction heating, and the material to be melted is continuously charged onto the heated heating medium. A method for continuously melting the material to be melted by heating and melting the material to be melted and flowing out the molten metal from a tap hole. In the electromagnetic induction heating, (1)
Inside the melting furnace where an electromagnetic coil is wound around the outer circumference of the furnace wall at a predetermined height
Then, a heating medium lower than the height of the electromagnetic coil is
Step of laminating from the part and heating it by electromagnetic induction heating in advance
If, (2) the power supplied to the electromagnetic coil is set to a constant value
In the state of being heated, the induction heating amount of 20
About 50%, and the remaining 80-50% to the material to be melted.
Put the material to be melted into the furnace so that
Laminate the desired temperature based on the lamination thickness of the heating medium
So that the voltage generated in the electromagnetic coil is
Or setting the impedance as a reference value in advance
If, (3) the melting material of the object to be dissolved material dissolved furnace is reduced
Voltage or impedance generated in the electromagnetic coil
The variation of the sensing is compared with the preset reference value and detected.
Output and fluctuation of the detected voltage or impedance
Re-introducing the material to be melted into the furnace so as to compensate for the
And a continuous heating and melting method comprising: 2. The method according to claim 1, wherein the power corresponding to the impedance variation is
When a plurality of types of materials to be melted are weighed to a predetermined amount and charged into the furnace, the respective weighing data of the plurality of types of materials to be melted are received, and an arithmetic unit receives the voltage. While integrating each weighing data, it is determined whether or not the blending ratio of those integrated amounts is within a predetermined range, and when the integrated value of any material to be melted exceeds this predetermined range, the 3. The continuous heating and melting method according to claim 2 , wherein the operation of taking out the material to be melted is controlled so as to stop the work of taking out the material to be melted. The method according to claim 3, wherein the dissolved material as a stage before turning on the heating medium the laminated, heating the bottom of the heating medium the layered by sucking the gas inside the furnace from the tap hole, the laminated When the upper portion of the heating medium reached the melting temperature of the material to be melted, the tapping hole was closed, and the lamination was performed.
A metal material in an amount not exceeding the weight of the heating medium is charged and melted, and after a predetermined time from the charging of the metal material, the tap hole is opened and the material to be melted is stacked on the heating medium . continuously heating and melting method according to claim 1 or 2 comprising possess the step of introducing into. 4. The heating medium laminated on the bottom of the furnace is 3,000
Having a specific resistance of 0 to 10,000 μΩcm,
The method according to any one of claims 1 to 3, wherein the material to be melted is made of a metal material. 5. The material to be melted is an iron material, the calorific value of the heating medium by electromagnetic induction heating is 20 to 50%, and the calorific value of the iron material is adjusted to the remaining 80 to 50%, and the molten material is adjusted from the tap hole. The continuous heating and melting method according to any one of claims 1 to 4, which is configured to obtain molten cast iron at 1,400 to 1,600 ° C. 6. The power supplied to said electromagnetic coil has a frequency of 500 to 5,000 Hz and an output of 100 to 1 Hz.
Continuous heating dissolution method of claim 1 wherein the 0,000KW.