JPH08233468A - Heating and melting device - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: A fine material such as pig iron can be used, and a high quality molten metal containing a small amount of gas such as oxygen and nitrogen can be continuously and stably prepared at a predetermined temperature. The present invention is to provide a heating and melting device. SOLUTION: A hot water outlet 5 that can be opened and closed is provided in the hearth.
The upper opening of the hearth is used as the material-to-be-melted inlet, and the inside of the furnace is filled with a carbonaceous material 1 such as coke and a material-to-be-dissolved 2 such as an iron material. Electromagnetic coil 3 provided in the outer peripheral region of the melting furnace main body corresponding to the required heating region from the carbon material layer to the predetermined height of the material layer, and induction heating for supplying electric power such as high frequency power to electromagnetic coil 3. An energy applying unit and a unit for controlling this induction heating energy are provided, and the control unit controls the ratio of the amount of induction heating given to the carbon material 1 and the material to be melted 2, thereby controlling the tapping temperature to a predetermined temperature. Configure to get.

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 for metal materials and the like, and more particularly to a heating and melting apparatus suitable for continuous melting which is excellent in reducibility and can control the tapping temperature to a predetermined temperature.

[0002]

2. Description of the Related Art Cupola and crucible type induction furnaces are well known and widely used as cast iron melting devices.
The cupola is a continuous melting furnace that can continuously obtain a refined and high-quality molten metal, and the induction furnace is an intermittent melting furnace that can use fine materials and whose components can be easily adjusted. Each of them has advantages and disadvantages, and at present, a double dissolution apparatus using them together is widely used. Note that, for example, Japanese Patent Publication No. 52-48564 can be cited as one related to this type of technology.

[0003]

The cupola requires a large amount of air to be blown in order to burn the coke at a high temperature. Therefore, the gas flow velocity in the furnace is high, and for example, fine materials such as pig dalai are oxidized or melted. It is difficult to dissolve because it is discharged to the outside of the melting apparatus by the flow of gas before the melting. In addition, the heat source that heats and melts the material is the combustion of coke, so incomplete combustion is necessary to reach a high temperature, especially 1,50
In order to obtain the tapping temperature of 0 ° C or higher, the efficiency is lowered and it is difficult to control the temperature.

On the other hand, in the induction furnace, the scouring effect cannot be expected because melting is performed only by 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. 52-48564 mentioned in the prior art.
In the publication, an induction coil is installed on the upper part of the cupola to heat the material, but the heating of the coke layer is not taken into consideration. Therefore, a disadvantage for blowing a large amount of air, and a method for efficiently obtaining high temperature are Not improved.

That is, the above-mentioned conventional melting apparatus using both an induction furnace and a combustion furnace is a proposal for a continuous refining technique in which electromagnetic induction heating is used for low temperature heating and coke combustion heating is used 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 where the material to be melted is input, but it is so-called preheating that heats only the metal material that is the material to be melted that is flowing, and preheating with electric power is economically expensive. It is not practical. In addition, since the high temperature heating is a combustion method using coke, the efficiency is reduced due to the generation of CO due to incomplete combustion of coke, the size of the equipment is increased due to the generation of a large amount of exhaust gas, and pollution prevention measures are required. There is a problem that the material is scattered in a gas flow and becomes difficult to dissolve, and further, with combustion, oxidation of the metal by oxygen in the gas occurs, sufficient reduction does not proceed, and the oxide becomes slag.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art. 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. It is an object of the present invention to provide a heating and melting apparatus for realizing an improved electromagnetic induction heating method obtained by continuously and stably adjusting the temperature of a molten metal.

[0009]

In order to achieve the above object, a heating and melting apparatus of the present invention is provided with a tap hole that can be opened and closed in a hearth part, and a facing upper opening part of the hearth part is a material to be melted. It corresponds to a melting furnace main body that sequentially fills and stores a carbon material and a material to be melted inside the charging port, and a heating required area from the carbon material layer to the predetermined height of the material to be melted in the hearth. The carbon material is provided with an electromagnetic coil provided in the outer peripheral region of the melting furnace main body, induction heating energy applying means for supplying power to the electromagnetic coil, and means for controlling the induction heating energy. And by controlling the ratio of the amount of heat generated by the material to be melted,
It is characterized in that the tapping temperature can be controlled to a predetermined temperature.

More specifically, the ratio of the amount of heat generated by the carbon material to the amount of heat generated by the material to be melted by the electromagnetic induction heating by the induction heating energy applying means is controlled by the means for controlling the induction heating energy. , Controlling any one of output, current and voltage with a power source, changing the impedance of the electromagnetic induction coil by the input amount of the material to be melted, and controlling one of the other two, thereby It is characterized in that the tapping temperature is controlled to a predetermined temperature.

That is, one of output, current and voltage is controlled to be constant on the power supply side, and the impedance of the electromagnetic induction coil is changed by the amount of the carbon material and the material to be melted, and the remaining two are By controlling one of the constants, the ratio of the amount of carbon material and the amount of material to be melted in the furnace is kept constant,
The amount and ratio of the electric power absorbed by the carbon material and the material to be melted are controlled to be constant, and the temperature of the hot water discharged from the hot water outlet of the hearth can be controlled to a predetermined temperature. The output power is controlled to be constant, and either the current or the voltage is controlled based on the amount of the material to be melted, so that the tapping temperature is controlled to a predetermined temperature.

Further, in the apparatus of the present invention, heating means for preheating the material to be melted is provided in a predetermined region in the furnace up to the material to be melted introduction port outside the electromagnetic coil area of the melting furnace main body, and the charged material to be melted is introduced. It is also possible to preheat the material as it passes through the heating means and move it to the electromagnetic induction heating region.

The means for controlling the induction heating energy is
The induction heating energy applying means for supplying power to the electromagnetic coil is a means for supplying high-frequency energy, in which the amount of the material to be melted is controlled according to the impedance variation of the electromagnetic coil to control the tapping temperature. It is preferable that Therefore, the means for controlling the induction heating energy in this case is composed of high-frequency energy control means, and the impedance variation of the electromagnetic coil, which fluctuates depending on the feeding condition of the material to be melted, is configured to guarantee and stabilize its output by voltage fluctuation. It is to be.

A typical heating / melting apparatus of the present invention, which is practically preferable, has the above carbon material, for example, a specific resistance of 3,000.
~ 30,000μΩcm coke, high frequency energy to feed the above electromagnetic coil frequency 500 ~ 5,000Hz, output 100
Is about 10,000 kW, and the high-frequency energy control means is composed of control means for stabilizing and stabilizing the output of the impedance variation of the electromagnetic coil, which varies depending on the state of introduction of the material to be melted, by voltage variation. If, for example, iron material is used as the melting material, the tap water temperature is 1,400 to 1,600 at all times.
A continuous heating and melting apparatus capable of easily obtaining molten cast iron prepared at ℃ can be realized.

[0015]

[Function] Carbon materials have a higher electric resistance than metals,
For example, since coke having a specific resistance of about 5,000 μΩcm can be sufficiently heated by high frequency induction heating, by giving a part of the induction heating amount for melting the metal to the coke filled in the bottom of the furnace, air does not exist at all. This coke can be heated to the temperature required for metal melting as a heating medium in a non-atmosphere and thus without utilizing combustion.

Unlike the combustion method, this method can create a high-temperature atmosphere in which oxygen and nitrogen hardly exist, and the temperature can be easily 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 kept constant regardless of the melting rate. An atmosphere of temperature can be obtained.

That is, as described above, a carbon material such as coke is supplied with, for example, 20 to 50% of the amount of induction heating, and the remaining 50 to 50%.
By applying 80% to the material to be melted, the metal melted in this atmosphere can be brought into contact with the surface of the coke in a dropping manner for heating and refining, and even if a material that easily oxidizes, such as pig iron, is used, It can be melted at a constant temperature without generating slag.

Any carbon material can be used, but coke having a fixed resistance of 3,000 μΩcm or less is expensive and economically unfit, and since it is being graphitized, molten metal (for example, cast iron) is used. The carbon content in () is too large, and it is difficult to heat coke having a size of 10,000 μΩcm or more. Therefore, it is desirable to use one having a specific resistance of 3,000 to 10,000 μΩcm.

Further, since this furnace is a continuous melting apparatus, it is also an advantage that the material can be preheated continuously and efficiently. If the ratio of the induction heating amount to the carbon material part is 20% or less of the total heating amount including the heating amount by preheating, the heating amount after melting will decrease and the tapping temperature will be too low at 1,400 ° C or less. On the contrary, if it is 50% or more, the heating amount after melting increases and causes overheating to 1,600 ° C or more. Therefore, when it is desired to set the tapping temperature to 1,400 ° C to 1,600 ° C, the ratio of the amount of induction heating to the carbon material portion may be set to 20 to 50% as described above.

Further, power output 100 kW or less, frequency 5,000
The apparatus tends to be too small at Hz or higher, and tends to become too large at an output of 10,000 kW or higher and a frequency of 500 Hz or lower, which is generally not suitable for heating a metal material used for melting cast iron. Therefore, in the case of cast iron melting,
It is desirable that the power output is 100 to 10,000 kW and the frequency is 500 to 5,000 Hz.

At the start of the work, the hot water temperature tends to be low because the furnace body is not sufficiently heated, as in a general furnace. Charge the metal material, store the molten metal in the furnace,
The temperature can be raised by induction 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. In other words, when the material to be melted is put in the furnace, the impedance of the coil changes depending on the material and the state of the input, but this fluctuation is stably prevented by the voltage or current fluctuation of the control means, and the output etc. is kept constant. It is something to do. In an actual device, this control means is incorporated on the high frequency power supply side.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments according to the present invention will be described below with reference to FIGS.
This will be described below. FIG. 1 schematically shows the overall configuration of the heating and melting apparatus of the present invention, and FIG. 2 schematically shows the cross-sectional structure of the induction heating unit. In FIG. 2, 1 is the bottom of the furnace (also called the hearth in the text). Coke with a specific resistance of 5,000 μΩcm, 2 is 4 parts of return scrap, 3 parts of pig iron, 3 parts of electromagnetic steel plate press scraps, 3 parts of other materials to be melted such as iron silicide, and 3 is an electromagnetic coil, Reference numeral 4 is a refractory material having an inner diameter of 400 mm and a height of 700 mm, which forms a furnace body, 5 is a tap hole, 6 in FIG. 1 is a material supply device for supplying molten material to the furnace, and 7 is a capacity for continuously receiving molten metal. 150
kg pre-furnace, 8 material preheater by burner using general gas and liquid fuel, 9 frequency 3,000Hz, output 175k
W power source.

It should be noted that the use ratio of the fine material such as the pig iron slag of the material to be melted 2 and the electromagnetic steel sheet press scraps can be 0 to 70% with respect to the total melted material, but the induction heating and the atmosphere in the furnace are shut off. Therefore, it is preferable to use 20 to 60%.

When starting the melting operation, first, the thickness of the coke layer remaining in the furnace after the previous operation is adjusted to about 250 mm from the bottom of the furnace. If it is less than 250 mm, replenish with fresh coke. The thickness of this coke layer is necessary to change the heating rate and control the tapping temperature. The total weight of coke at this time is about 30 kg, and the number of coke is about 100.
The maximum weight of each piece was 2 kg. After the charging of the coke is completed, the power supply 9 supplies power to the electromagnetic coil 3.

Reference numeral 10 in FIG. 2 is a high frequency energy control means for compensating the impedance fluctuation of the electromagnetic coil caused by the fluctuation caused by the melting of the material 2 to be melted in the furnace with the voltage fluctuation. .

Coke with a large size in the upper part of the coke layer efficiently absorbs electric power to generate heat, but coke with a small size in the lower part does not easily generate heat. Therefore, the gas in the furnace is sucked from the tap hole 5 and the hot gas is discharged. It is effective to heat the lower part of the coke layer. At this time, the voltage was 1,120 V and the input was 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 dalaai as a metal material is charged and melted, and stored in the bottom of the furnace for further heating. By this operation, the inside of the furnace 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 above 1,500 ° C., the tap hole 5 is opened and the molten metal is introduced into the forehearth 7 and, at the same time, the material supply device 6 starts the introduction of the material 2 to be melted.

When the material is added, the upper part of the coke layer is closed with the material, and only the tap hole is connected to 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 is melted by receiving heat from the coke 1 at the bottom when the lumpy return scrap is induction-heated by the electromagnetic coil 3 and descends while the temperature rises and reaches the bottom layer. To do.

The melted material 2 in the form of droplets by being melted is further heated while the space between the coke 1 is sewn and dropped, and is further refined by the high temperature coke 1 and the reducing atmosphere in which oxygen is almost absent. After that, it is tapped from the tap opening 5.

Since the output from the power source 9 is constantly controlled by the high-frequency energy control means 10, when the melted material 2 in the furnace is decreased and the impedance of the coil 3 is increased and the voltage exceeds 1,000 V, the material is supplied. When the material is supplied into the furnace by the equipment, the molten material increases and the impedance of the coil decreases and the voltage drops below 1,000 V, the material supply equipment stops and the output and voltage during work are about 173 kW, respectively.
It is controlled to 1,000 V, and continuous dissolution is maintained in this state. The tapping temperature in this normal state was about 1,450 ° C.

Further, the time required to dissolve 1 ton of the material to be melted is 3.27 hours, the amount of electric power is 566 kWh at the input, the amount of coke supply is 11 kg, and the amount of slag generated cannot be measured, but it is extremely small. The damage to the refractory material was also very small. In the case of this embodiment, the burner (material preheating device 8) was not used, but if a burner is used, electric power can be saved and the tapping speed can be increased according to the heating amount. Moreover, the amount of electricity saved in a general crucible furnace is 20%.
In contrast to the following, since this furnace can continuously heat
Up to 30% was possible (with heavy oil burner).

Table 1 shows the relationship between the input when the coke layer is heated and the tapping temperature when the coke layer is melted in that state when the thickness of the coke layer laminated on the hearth is changed.

In any case, the no-load input is 32 kW,
The input during tapping was 173 kW. In this way, the tapping temperature can be controlled simply by changing the thickness of the coke layer, so that as the melting progresses and the level of the material in the furnace lowers, continuous melting at a constant temperature can be achieved simply by adding the material to be melted. Can be maintained.

[0036]

[Table 1]

Table 2 shows the analysis results of the chill depth and the gas content of the cast iron obtained by the general cupola melting and crucible type induction furnace melting, and the melting according to the present invention. At this time, the content of the material to be melted 2 was 30% as steel scrap, and the molten metal content was 3.3% carbon and 2.0% silicon. As is well known, the quality of cast iron is better as the chill depth is shallower and the gas content is smaller.
It will be clear from the above how the present invention is superior to other melting furnaces.

[0038]

[Table 2]

In the above description, the case where the cast iron is melted by using the coke has been described, but in the present invention, a refractory material having a dielectric property is used instead of the coke, other metals such as copper alloys and ores. (It is desirable to have conductivity)
It is possible to dissolve If you want to further reduce easily evaporating impurities such as zinc, provide a vent in the furnace,
It is also possible to blow an inert gas or a reducing gas to positively promote the evaporation of impurities.

As is apparent from the above examples, in the present invention, the temperature of the tapping water can be controlled, and since it is melted and heated in a strongly reducing atmosphere with little gas flow, even if a powdery material is used, conventional oxidation is performed. Almost no generation of slag based on this is observed, and a good quality metal with a low gas content of oxygen, nitrogen, etc. can be obtained.

As described above, the carbon material of the present invention acts as a heating element (heating medium) by induction heating and as a reducing agent in refining. Therefore, unlike the conventional heating and melting method by the combustion method, the carbon material itself is not exposed to the combustion gas, so that the consumption amount thereof is extremely small.

Further, since the combustion method is not used for heating the carbon material such as coke, induction heating is carried out in a state where the flow of air in the furnace is substantially cut off, and a reducing atmosphere in a preferable state is realized. As a result, since the amount of gas such as oxygen and nitrogen is small, it is possible to produce a high-quality dissolved product having a small gas content, no special exhaust gas treatment equipment is required, and preferable in terms of pollution prevention measures.

[0043]

As described above in detail, according to the present invention, the intended purpose can be achieved. That is, the heating and melting apparatus of the present invention can efficiently dissolve even fine materials such as pig iron, and the oxides can be reduced by the refining action of the heated carbon material and the strongly reducing atmosphere. Therefore, there is an effect that a high-quality metal having a small gas content can be continuously and industrially obtained with almost no generation of slag.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of the overall configuration according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view showing details of an induction heating unit of the furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Coke 2 ... Melting material 3 ... Electromagnetic coil 4 ... Refractory material 5 ... Exit gate 6 ... Material supply device 7 ... Front furnace 8 ... Material preheating device 8 '... Burner 9 ... Power supply 10 ... Control part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kokichi Nakamura 1-10-6 Takabedai, Tomitabayashi-shi, Osaka Prefecture (72) Inventor Haruki Sumimoto, Kamo-cho, Soraku-gun, Kyoto Pref.

Claims (7)

[Claims] 1. A hot water outlet that can be opened and closed is provided in the hearth.
A melting furnace main body that sequentially stores and stores a carbon material and a material to be melted therein while using the facing upper opening of the hearth as a material to be melted inlet, and a material to be melted from the carbon material layer of the hearth An electromagnetic coil provided in the outer peripheral region of the melting furnace main body corresponding to a required heating region up to a predetermined height of the layer, induction heating energy applying means for supplying power to the electromagnetic coil, and means for controlling the induction heating energy. A heating and melting apparatus comprising: a control means for controlling the ratio of the amount of heat generated by the carbon material and the material to be melted by induction heating to control the tapping temperature to a predetermined temperature. 2. When controlling the ratio of the amount of heat generated by the carbon material and the amount of heat generated by the material to be melted by the electromagnetic induction heating by the induction heating energy applying means, output by a power source,
A configuration in which any one of current and voltage is controlled, and one of the remaining two is controlled by the input amount of the material to be melted, thereby controlling the tapping temperature to a predetermined temperature. Item 2. A heating and melting apparatus according to Item 1. 3. In controlling the ratio of the amount of heat generated by the carbon material to the amount of heat generated by the material to be melted by electromagnetic induction heating by the induction heating energy applying means, the output is controlled to be constant by a power source, The heating and melting apparatus according to claim 1, wherein either one of the current and the voltage is controlled based on the amount of the melted material to be supplied, and thereby the tapping temperature is controlled to a predetermined temperature. 4. The heating means for preheating the material to be melted is provided in a predetermined area in the furnace, which is located outside the electromagnetic coil area of the melting furnace body and reaches the material to be melted inlet. 3. The heating and melting apparatus described in 3. 5. The means for controlling the induction heating energy comprises:
The heating and melting apparatus according to any one of claims 1 to 4, wherein the amount of the material to be melted is controlled according to the impedance variation of the electromagnetic coil to control the tapping temperature. 6. The heating and melting apparatus according to claim 1, wherein the induction heating energy applying means for supplying power to the electromagnetic coil comprises means for supplying high frequency energy. 7. A means for controlling the induction heating energy,
7. A high-frequency energy control means, which is configured to guarantee and stabilize the output of an electromagnetic coil impedance variation that varies depending on the input state of the material to be melted by voltage variation. The heating and melting apparatus described.