JPH0293287A - Melting device and melting method - Google Patents

Abstract

PURPOSE:To reduce and melt minute grains of oxides such as iron sand to obtain the highly pure cast iron and facilitate the adjustment of the composition of carbon content by disposing an electromagnetic coil around the external surface of the furnace wall to subject a heater to electromagnetic induction heating. CONSTITUTION:The furnace body 1 is lined with ceramic refractory material, and the power having an intermediate frequency range is applied to an electromagnetic coil 2. Lumps 4 of black lead which is electrically conductive and refractory are induction-heated by the electromagnetic coil 2. The material 5 is melted by the radiation heat from the black lead lumps 4 and a small quantity of high-temperature gas which is generated by the reduction of the oxides, and is heated and reduced as it drops through the gaps between the black lead lumps 4 to be discharged from the outlet 3. Even if the material 5 is in the form of powder which can not normally be used or if it has been oxidized, it can be efficiently melted. When the grain size of the material 5 is suitable for the induction heating, the material itself generates heat due to the electromagnetic induction, resulting in the efficient melting. Since the preheating range of material is short, the time between the feeding of material and the discharge of molten metal also becomes short, and the adjustment of the contents can be facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a melting device, and more particularly to a melting device and a melting method equipped with a heating element made of a conductive refractory material suitable for melting high-purity materials.

[Conventional technology]

For example, cupola and crucible furnaces are well known and widely used as conventional cast iron melting devices. Cupola allows you to continuously obtain well-refined, high-quality molten metal.
It is a so-called continuous melting furnace, and the crucible furnace is a so-called intermittent melting furnace in which the melting temperature and components can be easily adjusted. Each method has its advantages and disadvantages, and a dual dissolution method using a combination of these methods is also widely used. Note that related devices of this type include, for example, Japanese Patent Publication No. 52-48564.

[Problem to be solved by the invention]

Cupolas require a large amount of air to be blown in to burn coke, a carbon material, at high temperatures, and have the following disadvantages:

(1) Requires extra heat to heat the air.

Furthermore, as the temperature increases, CO□ in the combustion generated gas is reduced again by coke and becomes CO, resulting in poor thermal efficiency.

(2) The gas flow rate in the furnace is high, and fine materials such as pig iron cannot be melted because they are discharged outside the melting device by the gas flow before being melted.

(3) Because heat is exchanged between the high-temperature, high-velocity combustion gas and the material, a large amount of material is present in the pre-heating zone, and it takes time from material input to melting, so the response speed is slow, and the content of C, Si, etc. It is very difficult to change or adjust the ingredients.

(4) Because coke is continuously melted by combustion, it is almost impossible to change the melting rate or temporarily stop melting in order to obtain a molten metal containing a constant temperature and components.

It is an intermittent melting method for main fishing, and there are problems such as the need for a starting block at the start. Furthermore, since the melting is performed simply by induction heating of the material, there is a problem that no scouring effect can be expected. Furthermore, it is inconvenient to feed molten metal to continuous casting equipment.

The purpose of the present invention is to provide a melting apparatus and a melting method that can use not only pig iron but also fine oxides such as iron sand, can adjust the temperature and contained components, and are suitable for obtaining high-purity molten metal. It is in.

[Means to solve the problem]

The above purpose is to provide a melting device that is composed of a heating element made of a conductive refractory material serving as a heat source and a furnace wall that houses the heating element, and in which a predetermined material passes between the heating elements after melting.
This is achieved by providing an electromagnetic coil outside the furnace wall and heating the heating element by electromagnetic induction.

[Effect]

For example, conductive refractory materials such as graphite and conductive ceramics have higher electrical resistance than metals, but can be used as heating elements because they can be sufficiently heated by medium-frequency induction heating. Therefore, by inductively heating the heating element in the melting zone with an electromagnetic coil, a heat source for the melting furnace can be obtained by means other than combustion.

Note that when the graphite heating element heated during melting comes into contact with the molten cast iron, the graphite of the heating element is easily absorbed by the cast iron.

This phenomenon is advantageous when producing cast iron with a high carbon content from cheap materials such as fine steel scraps with a low carbon content, but is disadvantageous when producing cast iron with a low carbon content. Therefore, in the latter case, by coating the surface of the graphite heating element with a ceramic material such as alumina, contact between graphite and cast iron can be interrupted and unnecessary increase in carbon content can be prevented. Furthermore, similar effects can be expected by using a ceramic such as a conductive sarlon, which is imparted with conductivity, as the heating element instead of the graphite heating element.

On the other hand, by using a graphite or carbon heating element made from charcoal, which has a low content of impurities harmful to cast iron, as has been effective in the manufacturing method of Japanese swords and Japanese iron since ancient times, High purity cast iron with few impurities can be obtained without consuming large amounts of charcoal, which is a disadvantage of the above production method.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

The figure is a longitudinal sectional view of the melting device. The melting device is furnace body 1,
It consists of an electromagnetic coil 2. The furnace body 1 is lined with a refractory material, and the electromagnetic coil 2 receives power in a medium frequency range. The graphite lump 4, which is a conductive refractory material, is the electromagnetic coil 2.
The material 5 is heated by induction, and is melted by radiant heat from the graphite lump 4 and a small amount of high-temperature gas generated by reduction of oxides, etc., and falls through the gap between the graphite lumps 4 and is further heated.

The hot water is reduced and discharged from the hot water outlet 3. In this way, even if the material is in powder form, which cannot normally be used, or if it is oxidized, it can be efficiently dissolved.

Moreover, if the size of the material 5 is sufficient for induction heating, it goes without saying that the material itself will generate heat due to electromagnetic induction and can be melted more efficiently.

In addition, since the pre-heating period for the material can be made very short, the time from when the material is added to when the hot water is discharged is short, and the contained components can be easily adjusted.

Further, in the following embodiments, a case where there is no ventilation hole has been described, but in the present invention, the ventilation hole is not limited to air, and it is also possible to blow inert gas or the like, for example.

Furthermore, the present invention is not limited to continuous melting, and of course can perform intermittent melting by temporarily closing the tap.

The table shows iron sand, F e 20 a (red iron),
The results of the analysis of the main components of molten metal obtained when using fine punching scraps of electrical steel sheets as raw materials are shown in percentages.

Table Results of principal component analysis after melting of various materials [Effects of the invention] According to the present invention, not only fine materials such as pig iron can be dissolved, but also fine oxides such as iron sand can be reduced and dissolved, resulting in high purity. In addition to being able to obtain cast iron, it is also possible to easily adjust the content of carbon and other components, especially by using a heating element with a ceramic surface.

[Brief explanation of the drawing]

The figure is a sectional view showing the configuration of an embodiment of the present invention. 1...furnace body, 2...electromagnetic coil, 3...royu mouth,
4... graphite ingot, 5... material,

Claims (1)

[Scope of Claims] 1. A melting device in which a metal material charged onto a graphite heating element made of a heated conductive refractory material serving as a heat source passes between the heating elements after being melted; A melting device characterized in that a heating element has a surface coated with a ceramic material such as alumina. 2. In a melting device in which a metal material placed on a heating element made of a heated conductive refractory material that serves as a heat source passes between the heating elements after being melted, the heating element is made of conductive ceramic. A dissolving device characterized by: 3. In a melting device in which a metal material placed on top of a heating element made of a heated conductive refractory material that serves as a heat source passes between the heating elements after being melted, the heating element is made of charcoal as a raw material. A melting device characterized by graphite or carbon. 4. Consisting of a heating element and a furnace wall that houses the heating element,
A melting device in which a predetermined material passes between the heating elements after melting, the melting device comprising an electromagnetic coil provided outside the furnace wall, and heating the heating element by electromagnetic induction with the coil. 5. A melting method for melting a metal or melting and reducing a metal compound using the melting apparatus according to claim 4.