JP2987908B2 - Arc electric furnace - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for operating a DC electric furnace or an AC electric furnace, and in particular, suppresses generation of nitrogen oxides (NOx) and prevents oxidation of molten metal. And a method of operating an electric furnace for reducing oxidation loss of valuable metals.

(Prior Art) Conventionally, an arc electric furnace used for refining steel is known as a furnace that generates an arc when a current flows between electrodes and melts the steel by using high heat of the arc.

An ale-type arc furnace, which is well known as an arc electric furnace, generates an arc by passing an electric current with a slight distance between an electrode and an insert to generate high heat, and uses this heat for melting and refining.

(Problems to be Solved by the Invention) However, the conventional arc electric furnace has a problem that NOx, which is a kind of air pollutant gas, is liable to be generated, which leads to a recent problem of global environmental pollution. The generation of such NOx is due to the somewhat high oxygen concentration in the electric arc furnace.

In the tapping section of the conventional electric furnace, air easily enters the furnace through the tapping hole, so that the oxygen concentration in the furnace easily increases, the amount of nitrogen oxides (NOx) generated is large, and air pollution is reduced. Was causing it to wake up. Molten metal is more oxidized,
There was a problem that there was much oxidation loss of valuable metals.

The present invention has been made in order to solve such a problem, and by closing a tapping hole of an electric furnace, the tapping port is closed, airtightness in the furnace is secured, and oxygen in the furnace is secured. Reduce the concentration
An object of the present invention is to provide an arc type electric furnace in which the generation amount of NOx is suppressed.

(Means for Solving the Problems) For this purpose, as shown in FIG. 1, the arc type electric furnace of the present invention includes a furnace body, a furnace lid for closing a furnace body upper opening, and a furnace lid penetrating therethrough. An electrode inserted into the furnace, a working port formed in the front wall of the furnace body, a tapping port formed in the rear wall of the furnace body, and connected to the tapping port to guide the tapping flow to the outside. And a lid that can open and close the tap hole is provided, and the lid has a cushioning material that moves with the lid and can be in close contact with the tip of the tapping tub. It is characterized by.

(Operation) According to the arc type electric furnace of the present invention, since the lid that can close the tap hole is provided, external air is prevented from entering the furnace through the tap hole, and the airtightness in the furnace is prevented. And the generation of nitrogen oxides (NOx) is suppressed, and the oxidation of valuable metals is also suppressed. Since the cover is provided with the cushioning material, sealing can be achieved even if slag, metal, or the like adheres to the tip of the tapping tub.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the arc electric furnace 1 has three electrodes 3, 4, 5 inserted through a circular furnace lid 2. This is because three-phase alternating current is used. The furnace shell 6 on the front side of the furnace has a slag port (work port) 7, which is opened and closed by a door 8. A tapping port 10 is provided on the back side of the furnace, and a tapping tub 11 for guiding a tapping flow to a ladle is attached to a furnace body 12. The furnace body 12 can be tilted up and down to a certain angle in a fully equipped state. In particular, it is designed to allow a large tilt angle to the furnace back side during tapping operation. The furnace lid 2 includes electrodes 3, 4,
5 can be turned around a point outside the furnace shell 6 in a state where it is mounted. The furnace shell 6 and the furnace lid 2 are lined with refractory.

As shown in FIGS. 2 to 4, on the upper part of the tapping tub 11,
An upper cover 14 is attached so as to close a groove forming a runner of the tapping tub 11.

The upper cover 14 can open and close the tapping tub 11 by rotating the opening / closing shaft 41. The opening / closing shaft 41 is connected to a motor 45 via a sprocket 42, a chain 43, and a sprocket 44 fixed thereto. The upper cover 14 is turned around the opening / closing shaft 41 by the forward or reverse rotation of the motor 45.

The end lid 22 that can open and close the tip 11a of the tapping tub can be opened and closed by a link mechanism using a motor 34 as a drive source.
The shaft 18 is rotated by a chain 19 that links the sprocket 16 and the sprocket 17 attached to the shaft 34 a of the motor 34, and an end cover 22 is attached to the ends of the first link 20 and the second link 21 attached to the other ends of the shaft 18. Is installed. End lid 22
Is rotatable about the opening / closing shaft 18 in the direction of arrow a or b shown in FIGS. 3 and 4.

Cushion material 24 attached to end side inner wall surface 22a
Is provided to improve the adhesion of the tapping tub tip 11a. Since the slag, the ingot, and the like are easily attached to the tip 11a of the tapping tub, the cushion material 24 can be used for hermetic sealing.

The end lid 22 can be moved in the left-right direction in FIG. 2 by the first air cylinder 25 and the second air cylinder 26, so that the cushion material 24 can be brought into close contact with the tip 11a of the tapping tub. ing.

During operation of the electric furnace, as shown in FIGS.
14 and end lid 22 are in the closed position. Therefore, the inside of the furnace is kept airtight, and air hardly enters from the outside, so that the oxygen concentration in the furnace is reduced and the generation amount of NOx is suppressed.

During tapping, the first air cylinder 25 and the second air cylinder
The rod 26 is extended, the end cover 22 is separated from the tip 11a of the tapping tub, and then the end cover 22 is flipped in the direction of arrow a shown in FIG. increase.
The upper cover 14 may open or close the tapping tub 11 by rotating the opening / closing shaft 41.

When replacing the tapping tub, the rods of the air cylinders 25 and 26 are extended to the left in FIG. 2 with the end lid 22 joined with the cushion material 24, and then the end lid 22 is rotated by the reverse rotation of the motor 34. It is lowered in the direction of arrow b in FIG. Thereby, the tapping tub 11 can be replaced.

According to the present embodiment, the first air cylinder 25, the second air cylinder 25,
Since the end cover 22 is pressed against the tapping end 11a by the pressing force of the air cylinder 26 with the cushion member 24 interposed therebetween, the tapping port 10 can be closed, and the airtightness in the furnace can be maintained. Therefore, the oxygen concentration in the furnace can be reduced, and the generation of nitrogen oxides can be suppressed.

(Effect of the Invention) As described above, according to the arc type electric furnace of the present invention, since the lid device capable of closing the tap hole is attached, outside air can enter the furnace from the tap hole. Thus, there is an effect that the oxygen concentration in the furnace can be reduced and the generation of the nitrogen oxide concentration can be suppressed.

[Brief description of the drawings]

1 is a schematic sectional view showing an arc type electric furnace according to an embodiment of the present invention, FIG. 2 is a schematic plan view showing a tapping part of the arc type electric furnace, and FIG. 3 is a direction of an arrow III shown in FIG. FIG. 4 is a view taken in the direction of arrow IV shown in FIG. 1 ... arc type electric furnace, 2 ... furnace lid, 3, 4, 5 ... electrode, 7 ... working port, 10 ... tapping port, 11 ... tapping tub, 12 ... furnace body, 14 ... Upper lid (lid), 22 ... End lid (lid), 24 ... cushioning material (lid).

Claims (1)

(57) [Claims] A furnace body; a furnace cover for closing an upper end opening of the furnace body;
An electrode inserted through the furnace lid into the furnace, a working port formed in the front wall of the furnace body, a tapping port formed in the rear wall of the furnace body, and a tapping port connected to the tapping port; A tapping tub for guiding the steel stream to the outside is provided, and a lid that can open and close the tapping port is provided, and the lid has a cushioning material that can be in close contact with the tip of the tapping tub, The arc-type electric furnace, wherein the cushion material is movable back and forth with respect to the tapping hole together with the lid.