JPS6018271A - Vessel for molten metal - Google Patents

Abstract

PURPOSE:To cool efficiently an electrode having permeability and to stir forcibly a molten steel by providing said electrode in the required position of a vessel so that a gas for cooling the electrode is supplied through the inside of the electrode to the inside of the molten metal. CONSTITUTION:A vessel for a molten metal is provided with an upper electrode 11 and a bottom electrode 8. Single-phase AC or DC current is passed between the electrode 11 and the electrode 8 to generate an arc 12, thereby heating and melting the molten metal 13 in the vessel. The electrode 8 is formed to have air permeability and a gas 11 for cooling the electrode passed through the electrode 8 to cool the same and is then introduced into the vessel so that the molten steel 13 is forcibly stirred.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vessel for molten metal for heating the molten metal therein by single-phase alternating current or direct current.

For example, a container typified by a movable ladle or tundish for receiving molten metal and performing C-kneading is generally lined with a refractory on the inside, as shown in Figure 1, which shows an example of 1 dollar a. It is composed of an outer plate C made of polished steel plate.

Furthermore, when pouring the molten steel d from the pour spout e into the tundish (not shown) and into the mold of a continuous casting machine, it takes a long time of up to two hours from the start of casting to the completion of casting. ' iJ3 Therefore, the temperature drop of the molten steel d during this period is unavoidable. For this reason, conventionally, as shown in Fig. 1, three water electrodes f with the neutral point of the melt 111d were inserted into the ladle from above, and the molten steel (1) was heated by the three-phase arc Q. However, since this method uses three-phase electrodes, the upper structure is not only complicated, but also three-phase electrodes.
Due to the mutual electromagnetic force, the phase electrode g is oily on the outside, so the amount of heat dissipated is large and the heat transfer efficiency to the molten lid is low.At the same time, the distance between the electrode f and the lining refractory is narrow. Combined with this, there was a problem in that the life of some of the refractories 1) was locally shortened, and this also became a constraint on increasing the heating capacity.

In order to deal with this problem, in recent years it has been considered to heat molten steel with an arc in single-phase alternating current or direct current. In this method, it is necessary to have an electrode of the other pole on the side of the container, such as a ladle. Therefore, it is necessary to install an electrode on the outer periphery or bottom of the container to connect the molten steel inside the container and the outer shell plate by penetrating the refractory. Methods such as arranging a large number of spiked materials or installing metal grids have been considered.

However, the spikes 4A are usually made of conductive metal C, which has a much lower melting point than molten steel and will completely melt away unless it is cooled. For this reason, we try to cool the spike material from one end, but it is not enough, and the spike material gradually melts and wears out, requiring short-term use or repair, which is very difficult to repair. I was right about the problem.

The present invention was made in view of the above circumstances, and it greatly extends the life of the electrode provided on the side of the container for molten metal when generating an arc using single-phase alternating current or direct current. The purpose of this project is to bring the heating technology using single-phase alternating current or direct current arc to a practical stage.

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

Fig. 2 shows an example of a ladle 1 according to the present invention.The outer surface of the ladle 1 is composed of a side plate 2 and a bottom plate 3 made of metal such as a steel plate, and a crane is mounted on the upper part of the side plate 2. A trunnion A4 is provided for transporting the vehicle.

The inner surfaces of the above-mentioned side plates 2 and bottom plate 3 are lined with refractories 5 and 6, and a bottom electrode 8 and a casting sprue 9 are provided in the bottom part 7 composed of the bottom plate 3 and the refractories 6.

The bottom electrode 8 has air permeability and is designed to allow cooling gas 10 to pass therethrough.

As described above, the ladle 1 is fixed at a heating position by a crane or the like, and electricity is passed between the upper electrode 11 and the bottom electrode 8 to generate an arc 12 and heat the molten steel 13. A contact (not shown) connected to a power source 15 is provided, and an external connection terminal 14 is provided on the bottom electrode 8 so as to be electrically connected to the contact in a stationary state. In addition, the structure is such that it is completely grounded in a stationary state to prevent electric shock.

Figure 2 shows the case where the power source is a DC power source, and shows a state in which the upper electrode 11 is connected to the negative electrode and the bottom mold 4 rainbow 8 is connected to the positive electrode.When melt #113 is stored, the bottom electrode 8
Cooling gas 10 is passed through the molten steel 13, and while maintaining the state in which the cold gas 10 is passed through, both electrodes 8 and 11 are energized to generate an arc 12 and heat the molten steel 13.

The cooling gas 10 passes inside the bottom electrode 8 and cools the electrode 8, so the cooling efficiency is extremely high, and melting loss is effectively prevented. Promote uniformity and uniformity of ingredients.

The bottom electrode 8 has various structures that affect its air permeability, such as a hollow structure, a structure with many pores, a porous structure, etc., and the material of the electrode may be metal or conductive fireproof. I can think of things. Further, a cable may be connected to the external connection terminal 14, and the connection may be made manually or automatically. Furthermore, the location where the bottom electrode is provided is not limited to the bottom of the container, but may also be on the side.

Furthermore, in addition to inert gases such as argon gas and nitrogen gas, the cooling gas may also be hydrocarbons, etc., depending on the case.
The stirring makes it possible to equalize the temperature and composition of the molten steel.

As described above, according to the present invention, (1) the electrode is directly cooled, so the cooling efficiency is high and the life of the electrode is long; (ii) the structure is simple; and (g) molten steel can be forcibly stirred by cooling gas. Therefore, the composition and temperature can be adjusted, and since the electrode is provided below the container, the arc is vertical, so there is less wear and tear on the furnace wall due to heat, and thermal efficiency is good.

[Brief explanation of drawings]

FIG. 1 is an explanatory view showing an example of a heating method used in a conventional ladle, and FIG. 2 is a sectional view showing an example of a ladle implementing the present invention. 1 represents one dollar, 8 represents the bottom electrode, 10 represents the cooling gas, 11 represents the upper electrode, 12 represents the arc, and 13 represents the molten steel.

Claims (1)

[Scope of Claims] 1) In a container in which molten metal is heated by generating an arc with a single-phase alternating current or direct current, an electrode for controlling air permeability is provided at a predetermined position of the container, and an electrode inside the electrode is provided. A container for molten metal, characterized in that it has a groove for feeding electrode cooling gas into the molten metal.