JPH08260064A - Continuous heating and melting method - Google Patents

Abstract

PURPOSE: To enable use of powdery iron scrap and to produce molten pig iron excellent in the quality in good electric power efficiency by piling lumpy cokes as heating medium at the bottom part and using a cylindrical type melting furnace having a high-frequency boil for controllable induction heating at the outer side. CONSTITUTION: A molten iron tapping hole 5 is arranged at the bottom part 13 of the refractory-made cylindrical type melting furnace 12, and the coil 3 for high-frequency induction heating connected with a high-frequency power source 9 and a power control unit 110 is arranged at the outer periphery of the furnace. The lumpy cokes 1 as the heating medium are piled at the furnace bottom part and the electricity is conducted to the coil 3 for heating to induction-heat the cokes 1. The iron sources 2 mixed with fine size of turning iron waste, etc., are charged on the heated cokes 1, heated, melted and sufficiently reduced by flowing down while passing through between the cokes 1 to make the good quality pig iron having extremely little oxide content. In this case, the temp. of molten iron discharged from the iron tapping hole 5 is adjusted to a prescribed temp. by controlling the high-frequency power supplied into the coil 3 to the constant with the power control unit 110.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Cupola and crucible induction furnaces are well known and widely used as cast iron melting devices. The cupola is a continuous melting furnace in which a refined high-quality metal melt (hereinafter abbreviated as melt) is continuously obtained, and the induction furnace is an intermittent melting furnace in which fine materials can be easily adjusted. Each of these has advantages and disadvantages, and at present, a double dissolution method using both of them is widely used.

As a technique related to this type of technique, there is, for example, Japanese Patent Publication No. 52-48564.

[0004]

The cupola requires a large amount of air to be blown into the furnace in order to burn the coke at a high temperature. Therefore, the gas flow velocity in the furnace is high, and a fine material such as pig iron It is difficult to dissolve because it is discharged out of the melting apparatus by the gas flow before it is oxidized or melted. Further, since the heat source for heating and melting the material is due to the combustion of coke, incomplete combustion accompanies the high temperature, and in particular, the efficiency is lowered and it is difficult to control the temperature in order to obtain the tapping temperature of 1,500 ° C or higher.

On the other hand, in the induction furnace, the refining effect cannot be expected because the melting is performed only by the induction heating of the material. Further, there is a problem that it is basically an intermittent melting method and it is inconvenient to supply the molten metal to a continuous casting apparatus.

Further, Japanese Patent Publication No. 52-4 mentioned in the prior art.
In Japanese Patent No. 8564, an induction coil is installed above the cupola to heat the material, but heating of the coke layer is not considered at all, and therefore a disadvantage for blowing a large amount of air and high temperature can be obtained efficiently. There is no improvement in the measures to be taken.

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

That is, in this type of conventional technique,
Induction heating is used in the low temperature heating of the upper part of the furnace where the molten material is charged, but it is used as a so-called preheating means for inductively heating only the flowing metallic material that is the material to be melted. Preheating is economically expensive and impractical. Further, since the high temperature part located in the lower part of the furnace is a combustion system using coke, the efficiency is reduced due to the generation of CO due to the incomplete combustion of the coke, the device is enlarged due to the generation of a large amount of exhaust gas, and pollution prevention measures are taken. Need of,
The point that the fine material to be melted is scattered by the gas flow and it becomes difficult to melt,
Further, there is a problem that the metal is oxidized by oxygen in the gas with the combustion, the reduction does not proceed sufficiently, and the oxide becomes slag.

Therefore, an object of the present invention is to solve the above-mentioned conventional problems, and the object is to use a fine material such as pig iron and to provide a high quality product containing a small amount of gas such as oxygen and nitrogen. An object of the present invention is to provide an improved melting method by electromagnetic induction heating, which is obtained by continuously and stably adjusting the temperature of a molten metal.

[0010]

In the continuous heating and melting method of the present invention for achieving the above object, a bottom part of a furnace is provided with a tap hole at the bottom of the furnace and an inlet for the material to be melted at the top. At least one of the carbon material and conductive refractory material is laminated on top as a heating medium, and electric power is supplied to the electromagnetic coil provided on the outer periphery of the furnace wall to electromagnetically heat the laminated heating medium. Is a continuous heating and melting method of the melted material in which the melted material is continuously charged into the heated heating medium to melt the melted material, and the melt is discharged from the tap hole. In the electromagnetic induction heating, the power supplied to the electromagnetic coil is controlled to a constant value required for melting by the power control device on the power source side, and the ratio of the amount of heat generated by the heating medium and the material to be melted is adjusted. Constant in advance In addition, any one of the parameters consisting of current and voltage that fluctuates based on the melting of the material to be melted is controlled to maintain a predetermined reference value, and based on this reference value, It is characterized in that the amount of the melted material to be charged into the furnace is adjusted so that the temperature of the molten metal flowing out from the tap hole is adjusted to a predetermined temperature.

Preferably, the voltage corresponding to the electric power is received, and when the voltage is higher than the reference voltage, the material to be melted is charged into the furnace, and when the voltage is lower, the charging is stopped automatically. The amount of the molten metal is controlled so that the temperature of the molten metal flowing out from the tap hole is adjusted to a predetermined temperature.

More specifically, at least one of the carbon material and the electrically conductive refractory material is provided on the bottom of the furnace, which has a tap hole at the bottom of the furnace and an inlet for the material to be melted at the top. By laminating as a heating medium and 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 heated on this heating medium. A method for continuously heating and melting a material to be melted by continuously charging and melting the material to be melted, and continuously flowing out the melt from a tap hole. In the electromagnetic induction heating, the material is supplied to an electromagnetic coil. The power is controlled to be constant by the power control device on the power source side, and the ratio of the amount of heat generated by the heating medium and the material to be melted is set to a fixed value in advance, and changes as the material to be melted is melted. Electromagnetic The impedance variation of the electromagnetic coil is compensated by changing either the voltage or the current applied to the electromagnetic coil, the voltage corresponding to the electric power is received, and if this voltage is larger than the reference voltage, the furnace It is characterized in that the material to be melted is charged into the inside, and when the amount is small, the amount to be charged is controlled so as to stop the charging, and thereby the temperature of the molten metal flowing out from the tap hole is adjusted to a predetermined temperature.

When the above-mentioned voltage is monitored and a plurality of kinds of materials to be melted are weighed by a predetermined amount from the material-to-be-melted material inlet and charged into the furnace, the weighing data of each of the plurality of materials to be melted is measured. Upon receipt of the data, the calculation device integrates each weighing data, and it is judged whether the blending ratio of the integrated amounts is within a predetermined range, and the integrated value of any material to be melted is within the predetermined range. When the temperature exceeds the limit, the operation of taking out the material to be melted is controlled so as to stop the operation of taking out the material to be melted.

More preferably, the layered heating medium is preheated before the material to be melted is put on the layered material (heating medium). For this purpose, for example, heating by layering the material to be melted is performed. Before charging onto the medium, the lower part of the laminated heating medium is heated by sucking the gas inside the furnace from the tap, and when the upper part of the heating medium reaches the melting temperature of the material to be melted, the tap is opened. By closing and pouring an amount of metal material that does not exceed the weight of the heating medium to melt, 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. Normally used high frequency energy has a frequency of 5
0 to 5,000 Hz and output is 100 to 10,0
It is 00 kW.

A preferable distribution of the calorific value by the typical electromagnetic induction heating is that the calorific value of the heating medium laminated on the bottom of the furnace is 20.
.About.50%, and the amount of heat generated by the material to be melted is 80% to 50%. As a result, 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 the heating medium is
Coke is preferable, for example, 3,000 to 10,
A material having a specific resistance of 000 μΩcm is used.
Further, as the material to be melted, for example, a scrap usually called scrap iron, a press scrap, and a fine metal material such as pig dalai are used. Although a fine material such as pig iron can be used alone, it is usually used as a mixture of scrap and press waste, for example, 20 to 60%.

[0018]

The carbonaceous material or conductive refractory which is the heat generating medium has a higher electric resistance than metal, but for example, coke having a specific resistance of about 5,000 μΩcm can be sufficiently heated by high frequency induction heating. Therefore, by giving a part of the induction heating amount for melting the material to be melted, for example, the metal, to the coke charged in the bottom of the furnace, the coke can be treated in an atmosphere where there is no air, and therefore without utilizing combustion. The heating medium can be heated to a temperature required for melting the metal.

Unlike the combustion method, this method can create a high temperature atmosphere in which oxygen and nitrogen hardly exist, and the temperature can be controlled by changing the ratio of the amount of heat given to the coke.

Specifically, by keeping the ratio of the amount of coke and the amount of metal in the induction heating region in the furnace constant, the ratio of the electric power absorbed by the coke and the metal is kept constant and is related to the melting rate. Instead, it is possible to obtain an atmosphere of a constant temperature. 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 contacted in this atmosphere to perform heating and refining. Even if a material such as Dalai that is easily oxidized 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 expensive and not economically suitable, and is also melted due to the progress of graphitization (for example, cast iron). The carbon content in) is too much, and the coke having an excess of 10,000 μΩcm is difficult to heat, so the specific resistance is 3,000 to 10,
It is preferable to use the one of 000 μΩcm.

The present invention is also characterized in that the continuous melting apparatus is used so that the material can be preheated continuously and efficiently. In the electromagnetic induction heating of the present invention, when the ratio of the induction heating amount to the carbon material portion as the heating medium is less than 20% with respect to the total heating amount including the heating amount by preheating, the heating amount after melting The temperature of the molten metal is 1,
If it is less than 400 ° C, which is too low, and if it exceeds 50%, the amount of heat after melting increases and exceeds 1,600 ° C, causing overheating. For this reason, the tap water temperature should be 1,400-1,60.
When it is desired to set the temperature to 0 ° C., it is a practically suitable 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, the power output 100 of high frequency energy
If the power is less than kW and the frequency exceeds 5,000 Hz, the device becomes too small, and the output exceeds 10,000 kW and the frequency is 50.
Below 0 Hz, the device tends to be too large. Therefore, in the case of melting cast iron, the power output is 100 to 1
It is desirable that the operation is performed at a frequency of 50,000 kW and a frequency of 500 to 5,000 Hz.

At the beginning of the work, the temperature of the hot water tends to be low because the furnace is not sufficiently heated. In this case, the hot water outlet is temporarily closed and a metallic material such as pig iron is put in advance. The temperature can be raised by accumulating molten metal in the furnace and inductively heating this metal.

In the induction heating, connecting the high frequency energy control means between the high frequency energy applying means (power source) and the induction heating electromagnetic coil is effective in stabilizing the output fluctuation. That is, when the material to be melted is put into the furnace, the impedance of the coil varies depending on the material and the state of introduction, but this variation is stably compensated by the voltage or current variation of this control means to make the output constant. To do.

[0026]

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

(1) Structure of Melting Device The furnace 12 is composed of a substantially cylindrical refractory material 4 having an openable / closable tap hole 5 in the furnace bottom 13 and a melted material inlet 11 in the upper part. Has been done. Refractory 4 has an inner diameter of 40
The height is 0 mm and the height is 700 mm. Dissolved material inlet 11
Above the above, an annular preheating means 8 having a burner 14 using a general gas or liquid fuel is provided.

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

A control means 10 for controlling high frequency energy is interposed between the power source 9 and the material supply means 6. The control means 10 controls the melted material 2 charged into the furnace.
Is a high-frequency energy control means for compensating for the impedance variation of the electromagnetic coil 3 caused by the melting of the.

The frequency of the high frequency energy from the power source 9 is 3,000 Hz, and the output is 175 kW. The molten metal flowing out from the tap hole 5 has a capacity of 150 kg for the front furnace 7
Received by.

The carbon material 1 is laminated as a heating medium on the furnace bottom portion 13 inside the furnace 12, and the material to be melted 2 is supplied onto the carbon material 1 by the material supply means 6. The carbon material 1 is, for example, coke, and the specific resistance of this coke is 5,000 μΩcm. Material to be melted 2
Is a mixture containing, for example, 4 parts of return scrap, 3 parts of pig iron, 3 parts of electromagnetic steel plate press scraps, and a small amount of additives such as iron silicide. It should be noted that the use ratio of the small material such as the pig iron of the material to be melted 2 and the electromagnetic steel plate press scrap is the total material 2 to be melted.
In contrast, 0 to 100% can be used, but induction heating,
Use of 20 to 60% is preferable for shutting off the atmosphere in the furnace.

(2) Example of continuous heating and melting method When starting the melting operation by the above-mentioned continuous heating and melting apparatus, first, after the last operation, the thickness of the coke layer remaining in the furnace 12 is measured. About 250 from the bottom 13
Adjust to mm. If it is less than 250 mm, replenish with fresh coke. The total weight of coke at this time is about 30k.
The maximum weight of g, the number of about 100, and one was 2 kg. After the charging of the coke is completed, the power supply 9 supplies power to the electromagnetic coil 3.

The control means 10 serves to compensate the impedance variation of the electromagnetic coil 3 by the voltage variation as described above. Large coke in the upper part of the coke layer efficiently absorbs electric power to generate heat, but small coke in the lower part does not easily generate heat. Therefore, the gas in the furnace is sucked from the tap 5 and the coke is heated by this high temperature gas. It is effective to heat the lower part of the layer.

At this time, the voltage is 1,120 V and the input is 82
It was 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 dalaai as a metal material is charged and melted, and this is stored in the furnace bottom part 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 rises to 1,500 ° C. or higher, the tap hole 5 is opened and the molten metal is introduced into the pre-furnace 7, and at the same time, the material supply means 6 starts the introduction of the material 2 to be melted.
When the melted material 2 is charged, the upper part of the coke layer is closed by the melted material, and only the tap hole 5 communicates with the outside. Since the tap hole 5 is also closed by the molten metal when tapping is started, the flow of air into the furnace is substantially cut off.

The melted material 2 charged into the melted material 2 is inductively heated by the electromagnetic coil 3 and is lowered in temperature while rising, and when it reaches the lowermost layer, it is also supplied with heat from the lower coke layer 1. To melt. The melted material 2 in the form of liquid droplets is further heated while the space between the cokes is sewn and dropped, and is refined by the high temperature coke and the reducing atmosphere in which oxygen hardly exists. Hot water is discharged from 5.

Since the output is constantly adjusted by the power source 9, when the melted material 2 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 melted material 2 in the furnace is increased, the impedance of the electromagnetic coil 3 is reduced accordingly, and when the voltage is lower than the reference voltage of 1,000 V, the material supply means 6 supplies the melted material 2. It automatically stops and the output and voltage during work are controlled to about 173 kW and 1,000 V, respectively, and continuous melting is maintained.

In this steady state, the tap water temperature is about 1,4
It was 50 ° C. Also, the time required to dissolve 1 ton of material to be melted is 3.27 hours, and the electric energy is 566 kW at input.
h, the amount of coke replenished was 11 kg, and the amount of slag generated could not be measured, but was extremely small, and the damage to the refractory material 4 was also very small. In the case of this embodiment, the burner 14
Although the preheating means 8 provided with was not used, if this is used, electric power can be saved and the tapping speed can be increased depending on the heating amount. Moreover, while the amount of electric power saved in a general crucible furnace is 20% or less, when the auxiliary means 8 is used (the heavy oil burner is used) in the present invention, the amount of electric power saved can be up to 30%.

Table 1 is a table showing the relationship between the thickness of the coke layer 1 laminated on the bottom of the furnace and the input power when 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 1,000 V and the input power was 173 kW.
Coke layer 1 when it is actually melted by supplying
2 is a table showing the relationship between the thickness of molten iron and the temperature of tapping water.

[0043]

[Table 2]

As shown in Table 2, the tapping temperature can be controlled to a predetermined temperature simply by changing the thickness of the coke layer 1. Therefore, as melting progresses and the level of the material 2 to be melted in the furnace decreases, Continuous melting for obtaining a molten metal having a constant temperature can be maintained only by adding the material 2 to be melted.

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

Table 3 shows the analysis results of the chill depth and the gas content of the cast iron obtained by the general cupola melting and melting in a crucible induction furnace and the continuous heating melting method according to the present invention. At this time, the composition of the melted material 2 is steel scrap 3
It was measured under substantially the same conditions such that the content of the molten metal containing 0% was 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 the content of gas is smaller.
From this Table 3, it will be clear how the method of the present invention is superior to other dissolution methods.

[0047]

[Table 3]

In the above description, the case where coke is used to melt cast iron has been described, but in the present invention, a refractory material having conductivity (eg, conductive ceramics) is used instead of coke.
It is possible to dissolve other metals such as copper alloys and ores (preferably having conductivity) by using.

If it is desired to further reduce easily evaporated impurities such as zinc, it is possible to provide a vent in the furnace and blow an inert gas or a reducing gas to positively promote the evaporation of the impurities. .

As is clear from the above examples, according to the present invention, the material to be melted is melted and heated in a reducing atmosphere with a small gas flow, so that even if a powdery material is used, conventional oxidation is performed. Almost no generation of slag based on the above is observed, and a good quality molten metal with a small gas content of oxygen, nitrogen, etc. can be obtained.

As described above, referring to FIGS. 3 and 4, the structure and operation of the material supplying means 6 (hereinafter, simply referred to as supplying means 6) for the material to be melted 2 and the high-frequency energy applying means 9 Also, the relationship with the control means 10 will be described in detail. FIG. 3 is a block diagram of a control system for explaining the operation of the supply means 6 for charging the melted material 2 into the furnace, and FIG. 4 is a perspective view showing the configuration 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, and measures the required amount of the material to be melted 2 to be charged, and from this charging device 103, the material to be melted 2 is fed. Is charged into the furnace 12. That is, the feeding means 6 illustrated here is the material hopper 201.
For example, each of the three types of the material to be melted 2 taken out from the hopper 201 by the extracting means 200 including a lifting magnet (200L, 200M, 200N) for picking up the three types of material to be melted 2 is measured. The electronically controlled balance 202 (202A, 202B, 202C) using a strain gauge for

As shown in FIG. 3, the control means 10 comprises 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
It has an arithmetic unit 107 for blending three kinds of materials to be melted in a predetermined ratio based on the weighing data from (202A, 202B, 202C).

The voltage comparison device 105 has control lines (114, 115) for controlling the material take-out means (200L, 200M, 200N), respectively, and compares the voltage sent from the line 104 with the reference voltage. When is high, a signal is output to the control line 115, and when it is low, a signal is output to the control line 114.

The computing device 107 includes the balances 202 (202
(A, 202B, 202C) via line 112 and each fetching means 2 via line 113.
00 (200L, 200M, 200N) is controlled.

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

Further, the high frequency energy applying means 9 includes
The voltage supplied to the electromagnetic coil 3 of the furnace 12 via the lead wire 108 is converted into a corresponding low DC voltage, and the converted DC voltage is converted into the voltage comparison device 105 of the control means 10.
The voltage conversion device 111 for sending to

The operation of the block diagram of FIG. 3 will be specifically described as follows. When the melting progresses and the material 2 to be melted in the furnace 12 decreases, the impedance of the electromagnetic coil 3 increases. The electric power control device 110 controls the electric power supplied to the electromagnetic coil 3 of the furnace 12 so as to be constant, so that when the impedance of the electromagnetic coil 3 increases, the electromagnetic coil 3 is increased.
The voltage applied to it rises. This voltage is converted into a corresponding low DC voltage by the voltage conversion device 111 and supplied to the voltage comparison device 105.

A reference voltage is applied to the voltage comparator 105 from the reference voltage generator 106. Thus, when the voltage from the voltage conversion device 111 becomes higher than the reference voltage, a signal is output from the line 115 to each extraction means 200 (2).
00L, 200M, 200N), each take-out means 200 is activated, and the work 2 for taking out the material 2 to be melted is performed.

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

In this way, the respective melted materials 2 taken out under a certain constant condition are respectively controlled by the electronically controlled scale 202.
Accurately measured by (202A, 202B, 202C), 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 via 2 is within a certain range with respect to the desired value, the signal from the voltage comparison device 105 is transmitted via the line 115. As long as it is out, each take-out means 200 (200
L, 200M, 200N) continue to operate. However, if 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 taking out the material 2 to be melted through the line 113 so as to stop the operation for taking out the material 2 to be melted until the mixing ratio is within a certain range with respect to the desired value. Each material 2 to be melted is supplied to the furnace 12 by the charging device 103 as soon as the weighing is completed.

When the amount of the melted material 2 in the furnace 12 increases,
The impedance of the electromagnetic coil 3 decreases, and the electromagnetic coil 3
When the voltage applied to the voltage comparator 111 decreases, the voltage sent from the voltage converter 111 to the voltage comparator 105 via the line 104 decreases. When this voltage becomes lower than the reference voltage,
The voltage comparison device 105 sends a signal to each take-out means 200 (200L, 200M, 200N) via the line 114 to stop the operation of each take-out means.

Since the apparatus of the present invention is operated in this manner, the supply means 6 does not have to weigh each of the materials to be melted by the weighing device each time, like the material to be melted supply of the cupola. It is possible to quickly and accurately supply each melted material 2 to the furnace 12 simply by accurately weighing the melted material 2 taken out by each take-out means 200.

Weighing device 202 (202A, 202B, 2
02C) is, for example, an upper balance equipped with a load cell, which can include means for converting the 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.
It also acts as a reducing agent in refining. Therefore,
Unlike the conventional heating and melting method by the combustion method, the carbon material or the electrically conductive refractory itself is not exposed to the combustion gas, so that the consumption amount is extremely small. Further, without using a combustion gas for heating the carbon material or the conductive refractory material, since the carbon material or the conductive refractory material is heated by electromagnetic induction in a state where the flow of air in the furnace is substantially cut off, A reducing atmosphere in a preferable state is realized. As a result, it is possible to manufacture a high-quality molten metal having a low gas content of oxygen, nitrogen, etc., and no special exhaust gas treatment equipment is required, which is preferable in terms of pollution prevention measures.

[0067]

As described above in detail, according to the present invention, the intended purpose can be achieved. That is, it is possible to efficiently dissolve even fine materials such as pig iron, and oxides can also be reduced by refining work of a heated carbon material and a reducing atmosphere, and almost no slag is generated. Continuous, high quality metal with low gas content,
Moreover, there is an effect that it can be industrially obtained.

[Brief description of drawings]

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

FIG. 2 is a vertical cross-sectional view of the essential parts showing the details of the furnace.

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

FIG. 4 is a perspective view showing the structure of the supply means.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Carbon material, 2 ... Melting material, 3 ... Electromagnetic coil, 4 ... Refractory material, 5 ... Gate, 6 ... Supply means, 7 ... Front furnace, 8 ... Preheating means, 9 ... High frequency energy applying means, 10 ... Control means, 11 ... Melted material charging port, 12 ... Furnace, 13 ... Furnace bottom part, 14 ... Burner, 103 ... Conveyor, 104, 108, 112, 113 ... Line, 105 ... Voltage comparison device, 106 ... Reference voltage generation device , 107 ... Arithmetic device, 110 ... Power control device, 111 ... Voltage conversion device, 114, 115 ... Control line, 200 ... Material extracting means, 201 ... Hopper, 202 ... Electronically controlled balance.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location F27D 7/06 F27D 7/06 C

Claims (10)

[Claims] 1. A carbon material and at least one material of a conductive refractory material are laminated as a heating medium on the bottom of a furnace having a tap hole at the bottom of the furnace and an inlet for the material to be melted at the top. Then, by supplying electric power to the 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 put on the heated heating medium. A method of continuously heating and melting a material to be melted by heating and melting the material to be melted, and causing the melt to flow out from a tap hole. In the electromagnetic induction heating, power supplied to an electromagnetic coil is controlled by a power supply side. While controlling the constant value required for melting by the device, the ratio of the amount of heat generated by the heating medium and the material to be melted is set in advance to a constant value, and the current and the current that fluctuate based on the melting of the material to be melted From voltage One of the parameters is controlled so that it can maintain a predetermined reference value, and based on this reference value, the amount of the melted material to be charged into the furnace is adjusted, and the A continuous heating and melting method constituted so that the temperature of the molten metal flowing out is adjusted to a predetermined temperature. 2. A voltage corresponding to the electric power is received, and when the voltage is larger than a reference voltage, the material to be melted is charged into the furnace, and when the voltage is smaller than the reference voltage, the material is automatically charged so as to stop the charging. The continuous heating and melting method according to claim 1, wherein the amount is controlled so that the temperature of the molten metal flowing out from the tap hole is adjusted to a predetermined temperature. 3. A carbon material or at least one material of a conductive refractory material is laminated as a heating medium on the bottom of a furnace having a tap hole provided at the bottom of the furnace and an inlet for the material to be melted provided at the top. Then, by supplying electric power to the 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 put on the heated heating medium. A method for continuously heating and melting a material to be melted by heating and melting the material to be melted, and continuously flowing out the molten metal from a tap hole. In the electromagnetic induction heating, power supplied to an electromagnetic coil is supplied to a power source side. Of the electromagnetic coil that varies with the melting of the melted material, which is controlled by the electric power control device of FIG. The fluctuation is compensated by changing either the voltage or the current applied to the electromagnetic coil, and the voltage corresponding to the electric power is received. If this voltage is larger than the reference voltage, it is stored in the furnace. A continuous heating and melting method in which a melting material is charged, and when it is small, the charging amount is controlled so as to stop the charging, and thereby the temperature of the molten metal flowing out from the tap hole is adjusted to a predetermined temperature. 4. The weighing data of each of the plurality of types of melted materials when the plurality of types of melted materials are weighed by predetermined amounts from the melted material charging ports and charged into the furnace by monitoring the voltage. Upon receipt of the data, the calculation device integrates each weighing data, and it is judged whether the blending ratio of the integrated amounts is within a predetermined range, and the integrated value of any material to be melted is within the predetermined range. 4. The continuous heating and melting apparatus according to claim 3, wherein the operation of taking out the material to be melted is controlled so that the operation of taking out the material to be melted is stopped when the temperature exceeds the value. 5. The continuous heating and melting method according to claim 1, wherein the layered material is preheated before the material to be melted is put on the layered material. 6. Prior to charging the material to be melted onto the layered material, the lower part of the layered material is heated by sucking gas inside the furnace from the tap hole to heat the layered material. When the upper portion reaches the melting temperature of the material to be melted, the tap hole is closed, and a quantity of metal material that does not exceed the weight of the stacked materials is charged and melted, and after a predetermined time from the charging of the metal material. The continuous heating and melting method according to any one of claims 1 to 4, wherein the molten metal is put on the laminated material while the tap hole is opened. 7. The continuous heating and melting method according to claim 1, wherein the electromagnetic induction heating is performed by applying high-frequency energy to an electromagnetic coil mounted on the outer wall of the furnace. 8. The heating medium laminated on the bottom of the furnace is 3,000.
While having a specific resistance of 0 to 10,000 μΩcm,
7. The continuous heat melting method according to claim 1, wherein the material to be melted is made of a metal material. 9. The material to be melted is an iron material, the heat generation amount of a heating medium by electromagnetic induction heating is 20 to 50%, and the heat generation amount of the iron material is adjusted to 80 to 50% of the balance, and the heat is generated from the tap hole. The continuous heating and melting method according to any one of claims 1 to 6, which is configured to obtain molten cast iron at 1,400 to 1,600 ° C. 10. The frequency of the high frequency energy is 500.
~ 5,000 Hz, output is 100-10,000
The continuous heating and melting method according to claim 7, which is kW.