JPS6013014A - Ladle refining device - Google Patents

Abstract

PURPOSE:To perform refining of a metal and the vacuum evacuation in a ladle with one stage by closing airtightly a ladle with a furnace cover into which an electrode bar is inserted, passing DC current between the bottom electrode provided to the bottom of the ladle and the electrode bar and heating the molten metal by the DC arc. CONSTITUTION:A ladle 1 in which a molten metal 5 is received is carried to a prescribed position and is installed there. A furnace cover 3 through which an electrode bar 17 is inserted airtightly is suspended to a ring seat 12 and the bottom electrode 15 provided to the ladle 1 is connected to a DC power source 16. A gas blow port 4 is connected to a stirring gas source. Electricity is then conducted to the bar 17 and the electrode 15 to generate an arc 24 and the inside of the ladle is evacuated. An inert gas is fed as a stirring gas through the port 4 into the ladle. Then the molten steel 5 is heated by the arc 24 and is stirred by the stirring gas, by which the molten steel is refined. Since a space 22 is maintained under a negative pressure, harmful gas is removed. An additive is charged if necessary to the molten steel from a flux charger 19.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ladle refining device for molten metal that receives molten metal from a melting furnace and performs reduction refining in the presence of basic slag.

The molten metal melted in the melting furnace is poured into a ladle, transported to a casting machine, and cast.

In recent years, so-called ladle steel refining, which involves heating and refining during the process from receiving the metal in a ladle to casting, has become popular, and high-quality steel can now be produced efficiently and at low cost.

Conventional ladle refining devices include those shown in FIGS. 1 and 2, but they have various problems as described below.

First of all, in the case shown in Fig. 1, after the received steel plate 1 is installed in a predetermined position, the upper part of the steel plate 1 is covered with a furnace lid 3 into which a three-phase electrode 2 is inserted, and the three-phase electrode 3 is A three-phase alternating current is energized to generate an arc, and an inert gas is blown in from a gas inlet 4 provided at the bottom of the ladle 1 to stir the molten steel 5.

However, since such a method uses three-phase electrodes, it also requires a function to raise and lower the electrodes, making the electrode support structure complicated.

Further, the generated arc is also bent outward due to the mutual N magnetic force, so that the amount of heat dissipated is large and the amount of heat transferred to the molten steel 5 is low, and the inner wall of the ladle 1 is locally damaged.

Furthermore, hydrogen gas, oxygen, nitrogen dissolved in the molten steel 5,
Removing harmful gases such as carbon dioxide is important in improving the quality of steel, but when an arc is generated by three-phase alternating current, the surrounding structures are heated by induction heating phenomenon, so three-phase It is difficult to seal between the electrode 2 and the furnace lid 3, and it is difficult to evacuate the inside of the ladle 1. Therefore, in the example shown in FIG. 1, the molten steel is not evacuated.

Next, the one shown in Figure 2 is designed to allow vacuum evacuation.

The fact that the molten steel 5 is heated by a three-phase alternating current arc is similar to that shown in FIG.

In this example, the ladle 1 is stored in a sealed container 6, and
The inside is evacuated to create negative pressure.

In the figure, 7 is an exhaust port, 8 is an additive inlet, and 9 is an inert gas feed port.

In such a system, heating and evacuation must be performed alternately, which complicates the process, lowers productivity, and requires an evacuation device in addition to the heating device, making the device expensive.

The purpose of the present invention is to solve the above-mentioned problems of the conventional device.The present invention has a configuration in which molten metal can be heated by a direct current arc, and the molten metal can be sealed during the heating process. This can be done in one step.

The present invention will be described in detail below with reference to the drawings.

FIG. 3 shows a first embodiment of the present invention, in which numeral 1 indicates a steel plate and 3 a furnace lid.

The outer periphery of the ladle 1 is made of metal side plates 9 and bottom plate 1 made of steel plates, etc.
0, and a trunnion A 11 is provided at the upper position of the side plate 9 so that it can be transported by a crane etc.
A ring seat 12 is fixed to the outer periphery of the upper edge.

The inner surfaces of the side plate 9 and the bottom plate 10 described above are lined with a refractory 13, and the bottom formed by the bottom plate 10 and the refractory 13 is provided with a molten steel outlet 14, a gas inlet 4, and a bottom electrode 15. The structure is such that the gas inlet 4 can be connected to a stirring gas source (not shown), and the bottom electrode 15 and a DC power source 16 can be connected.

The furnace lid 3 is supported by a lifting device (not shown) so that it can be raised and lowered.

An electrode rod 11 is inserted through the center of the furnace lid 3.
A sealing device 18 is provided between the electrode rod 17 and the electrode rod 17 to make the electrode rod penetration part a sealed structure. Further, the furnace lid 3 is provided with a flux charging device 19 and an exhaust pipe 20 connected to an exhaust system such as a steam ejector (not shown).

In addition, 21 in the figure is a sealing device, and when the furnace lid 3 is covered with the ladle 1, the space 22 surrounded by the steel frame 1 and the furnace lid 3 becomes airtight. Further, 23 is a slag.

In the apparatus having the above-mentioned configuration, a steel draw 1 which has received molten steel 5 from a melting furnace is transported to a predetermined position by a crane (not shown) and installed.

The furnace lid 3 is placed on the ring seat 12, and the bottom electrode 15 is connected to a DC power source 16, and the gas inlet 4 is connected to a stirring gas source. Next, the electrode rod 17 and the bottom Nti
Is is energized to generate an arc 24 and the exhaust pipe 20
Then, an inert gas such as argon or nitrogen gas is supplied as a stirring gas from the gas blowing port 4.

Thus, the molten steel 5 is heated by the arc 24 and stirred by the stirring gas to perform refining. Furthermore, since the space 22 is under negative pressure, evacuation is actively performed to remove harmful gases.

Further, additives necessary for refining are charged from a flux charging device 19.

In the above-mentioned refining process, heating is performed by a DC arc using a single electrode, and there is no induction heating effect on the surrounding structures, so the space between the electrode rod 17 and the furnace lid 3 can be sufficiently sealed, and the electrode wear out. Since the arc length is small and the arc length can be controlled by controlling the voltage of the thyristor, the electrode rod 11 can be fixed or semi-fixed (fixed in the operating state), and the structure of the sealing device can be simplified.

FIG. 2 shows a second embodiment, in which a stationary sealed container 25 is provided to create a negative pressure around the molten steel 5.
The ladle 1 that has received hot water is carried into a stationary sealed container 25, sealed with a furnace/lid 3 in the same manner as in the previous embodiment, and the container 25 is evacuated.

Components in the figure that are the same as those in FIG. 3 are given the same reference numerals.

As described above, according to the present invention, (1) Only one electrode is required, and the electrode supporting device is easy to use. (n) The inner wall of the ladle is not damaged by arc, so the life is long. ) Since the electrode penetration part is easily sealed, it is possible to create a sealed space around the molten steel. (GV) Refining and vacuum evacuation can be performed in the same process, which simplifies the process. (V) Productivity It has various excellent effects such as: lyD equipment is compact, requires less installation space, and equipment costs are low; 6'5) Processing can be performed under vacuum or inert gas, so there is no oxidation of molten metal. demonstrate.

[Brief explanation of drawings]

Fig. 1 and Fig. 2 are explanatory diagrams of the conventional tn\R&I equipment;
FIG. 3 is a schematic diagram of the first embodiment of the present invention, and FIG. 4 is a schematic diagram of the second embodiment of the invention. 3 is a furnace lid, 15 is a bottom electrode, 16 is a DC power source, 17 is an electrode rod, 18 is a sealing device, and 20 is an exhaust pipe. Patent application person Ishikawajima Harima Heavy Industries Co., Ltd. Patent applicant agent

Claims (1)

[Claims] 1) The upper part of the ladle can be closed off with a furnace lid into which an electrode rod is inserted airtightly, so that air can be taken in from the space sealed by the furnace lid, and a bottom electrode is provided at the bottom of the ladle. 1. A steel refining apparatus, characterized in that it is configured to pass a direct current between a bottom electrode and the electrode rod to heat molten metal by means of a direct current arc.