JPS6325277B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resistance electric furnace, and particularly to the structure around its electrodes.

Traditionally, crushed slag stone, which is made by slowly cooling slag by-product from blast furnaces in steel plants, is remelted, and the composition and temperature are adjusted to create molten slag with a predetermined composition and temperature. It is being used to make fibers and produce rock wool. Recently, from the perspective of energy saving, molten slag from blast furnaces has been used directly, and its composition has been adjusted.
Techniques have also been developed to adjust the temperature to produce molten slag for fiberization. In these rock wool manufacturing processes, a resistance electric furnace is used to prepare molten slag for fiberization.

A resistance type electric furnace usually has two or three electrodes immersed in the material to be melted, and by passing electricity between each electrode and between the electrodes and the furnace wall or bottom, the material is melted by the resistance heat. An example of this is shown in FIG. 1. In the figure, a resistance type electric furnace includes an electrode 1, an electrode lifting device 2 that moves the electrode up and down, a furnace wall 3 that stores a material to be melted 5, and a furnace bottom 4.
and a power source (not shown) connected to the electrode 1, the furnace wall 3, and the furnace bottom 4. When melting and raising the temperature of the material 5 to be melted in this resistance electric furnace, the electrode 1
A part of the electrode is immersed in the material to be melted 5 using the electrode lifting device 2 and energized. Then, a current flows into the material to be melted 5 from the part of the electrode 1 that is immersed in the material to be melted.
The object to be melted 5 is melted and heated by the resistance heat.

However, in the conventional resistance electric furnace having the above structure, a temperature difference tends to occur between the upper and lower parts of the object to be melted 5, and as a result, the temperature of the object to be melted 5 cannot be made uniform, and the quality is affected. There was a problem with negative effects.

The present invention has been made in view of the problems of the prior art, and its purpose is to provide a resistance electric furnace capable of raising the temperature of a material to be melted to a uniform temperature.

In order to achieve the above object, the present inventor investigated the causes of temperature non-uniformity within a conventional resistance electric furnace, and as a result, discovered the following matter. That is, in the furnace, the upper part of the object to be melted 5 is generally at a higher temperature than the lower part due to convection, and the current resistance of the object to be melted at a high temperature is smaller than that of the object at a low temperature. In the structure in which current flows from the entire part immersed in the object 5 to be melted, a large amount of current flows to the upper part of the object 5, that is, the high temperature part, and the temperature tends to increase further. There was a considerable temperature difference between the top and bottom.

The present invention, which was made based on such knowledge, provides a resistance electric furnace having a plurality of electrodes partially immersed in the material to be melted, in which the electrodes are movable up and down by a lifting device, and each electrode has a The method is characterized in that a movable sleeve made of an insulating material or a substance having a higher electrical resistivity than the object to be melted is provided, and the movable sleeve is configured to partially interrupt contact between the electrode and the object to be melted. It is a resistance electric furnace.

The present invention will be explained below based on an embodiment shown in FIG. A movable sleeve 6 is provided around the outer periphery of the electrode 1 in a resistance electric furnace that has an electrode 1, an electrode lifting device 2 that moves the electrode up and down, a furnace wall 3 that stores a material to be melted 5, a furnace bottom 4, and the like. This movable sleeve 6 partially interrupts the contact between the electrode 1 and the object 5 to be melted, and in that part, the movable sleeve 6 partially blocks the contact between the electrode 1 and the object 5 to be melted.
It is provided to cut off or suppress the current flowing to the insulating material or the material to be melted. Preferred materials for the movable sleeve 6 include silicon carbide, silicon nitride, silicon nitride bonded silicon carbide, and the like.

The movable sleeve 6 is movable relative to the electrode 1 and is supported by a sleeve lifting device 7 provided separately from the electrode lifting device 2, so that the electrode 1 and the movable sleeve 6 can be moved up and down individually. . The sleeve elevating device 7 of this embodiment includes an arm 8 that supports the sleeve 6, an elevating block 9 that holds the arm 8, and a guide column 1 that vertically guides the elevating block 9.
0, it has a wire 11 for suspending the lifting block 9, a drum 12 for winding the wire 11, a drive motor 13 for the drum 12, and the like, and the sleeve 6 can be raised and lowered by the operation of the drive motor 13. The sleeve elevating device 7 is not limited to the illustrated structure, and other mechanisms capable of elevating the sleeve 6, such as a mechanism using a feed screw or a hydraulic cylinder, may be used.

Next, a temperature adjustment operation using the above-mentioned resistance type electric furnace will be explained. A part of the electrode 1 is immersed in the object 5 to be melted and electricity is applied to melt and/or raise the temperature of the object 5 to be melted. At this time, for example, the furnace bottom 4 of the material to be melted 5
If the temperature in the vicinity is low, the electrode 1 is further lowered using the electrode lifting device 2, and the movable sleeve 6 is lowered using the sleeve lifting device 7 to be immersed in the material to be melted 5. 1 and the object to be melted 5 is blocked by a movable sleeve 6. Thus, the resistance to current flow increases in the portion cut off by the movable sleeve 6, making it difficult for current to flow, and therefore, a large amount of current flows between the electrode 1 and the hearth bottom 4, increasing the temperature near the hearth bottom. If the temperature at the bottom of the furnace becomes too high, the movable sleeve 6 is raised to increase the contact area between the electrode 1 and the material to be melted 5, and current flows between the electrode 1 and the furnace wall 3 as well. The temperature may be made uniform by raising the electrode 1 or increasing the resistance between the electrode 1 and the furnace bottom 4. In this way, by adjusting the position of the electrode 1 and the position of the movable sleeve 6 with respect to the electrode 1, it is possible to adjust the distribution of the current flowing from the electrode 1 into the material to be melted, thereby controlling the temperature distribution in the furnace.

In the above embodiment, the movable sleeve 6 is configured to be raised and lowered independently of the electrode 1 by the sleeve lifting device 7, but the sleeve lifting device is omitted and the movable sleeve 6 is manually operated. Electrode 1
A structure may be adopted in which the electrode 1 is fixed to the electrode 1 after the position is adjusted relative to the electrode 1. The shape of the movable sleeve 6 is not limited to a simple cylindrical shape with a uniform thickness as shown in the figure;
As shown in the figure, a structure may be adopted in which a cut 6A whose width changes in the axial direction is provided so that the area covering the electrode 1 changes in the axial direction. Furthermore, instead of notches, a number of holes may be provided so that the opening area thereof varies in the axial direction, or the thickness of the sleeve 6 may vary in the axial direction. In this way,
It is preferable that the electric resistance of the movable sleeve changes in the axial direction, and the current distribution from the electrode 1 to the object to be melted 5 can be adjusted gently.

The resistance type electric furnace of the present invention can be used to re-melt crushed slag stone and adjust the composition and temperature to produce rock wool, or directly receive molten slag from a blast furnace and adjust the composition and temperature to produce rock wool. In addition to this, it can also be used to manufacture rock wool by melting natural rocks such as basalt and andesite, and to manufacture artificial stones other than rock wool. It can also be used for melting.

As explained above, according to the resistance electric furnace according to the present invention, a movable sleeve made of an insulator or a material having a higher electrical resistivity than the object to be melted is provided around the electrode, and the movable sleeve connects the electrode and the object to be melted. Since it is constructed so that contact with objects can be partially interrupted, the electric resistance of the section interrupted by the movable sleeve can be increased and the current flowing through this section can be suppressed, and as a result, the electrical resistance flowing through this section can be suppressed. The temperature inside the furnace can be made uniform by adjusting the current distribution within the melt.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view of a conventional resistance electric furnace, Fig. 2 is a schematic sectional view of a resistance electric furnace according to an embodiment of the present invention, and Fig. 3 is a side view showing the main parts of a modified example of the movable sleeve. It is a diagram. DESCRIPTION OF SYMBOLS 1... Electrode, 2... Electrode lifting device, 3... Furnace wall, 4... Furnace bottom, 5... Material to be melted, 6... Movable sleeve, 7... Sleeve lifting device.

Claims (1)

[Claims] 1. In a resistance electric furnace having a plurality of electrodes that are partially immersed in the material to be melted, the electrodes are movable up and down by a lifting device, and each electrode has an insulating material or an insulator on the outer periphery of the material than the material to be melted. 1. A resistance electric furnace comprising a movable sleeve made of a material with high electrical resistivity, and configured so that contact between an electrode and a material to be melted can be partially interrupted by the movable sleeve.