JPS59232210A - Method and device for refining molten steel - Google Patents

Abstract

PURPOSE:To perform refining without variance in component, temp., etc. in short time by stirring the molten steel in a vessel by suction and discharge and heating the molten steel. CONSTITUTION:A molten steel 2 is received into a ladle 1, etc. on a carriage 5 and is set in a refining position. A molten steel suction pipe 6 is descended by a lifting device 11 for the suction pipe and a pressure evacuating pump is started. A pressure evacuating valve 13 is opened to suck up the molten steel 2 in the ladle 1. The valve 13 is then closed and a pressure restoring valve 14 is opened to discharge the sucked-up steel 2 into the ladle 1 from diagonally above. The molten steel 2 in the ladle 1 is stirred by repeating such suction and discharge. On the other hand, an electrode 15 of a heater is descended into the molten steel during stirring of the steel 2 thereby heating the steel 2. The refining is executed in short time by the above-mentioned method and the temp. control thereof is made easy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a refining method and apparatus for performing processes such as desulfurization, deoxidation, composition adjustment, temperature adjustment, etc. in the ladle of molten steel received from a converter, arc furnace, etc. It is related to.

Conventionally, as a method for refining molten steel received in a ladle, as shown in Fig. 1, a porous plug (b) is placed at the bottom of the ladle (α).
There is a method in which an inert gas is blown into the porous plug (b) and the buoyancy of the gas bubbles f,) is used to stir the molten steel (d), thereby refining the steel.

However, this method has the following drawbacks.

(2) Since the buoyancy of gas bubbles (c) is used to stir the molten steel, the stirring power of the molten steel is weak.

■ If the diameter of the ladle (α) is large, uniform stirring cannot be achieved unless inert gas is blown into the ladle (α) from two or more porous plaques (b).

■ The blown gas expands and rises to form molten steel (d)
Since it is ejected from the top surface, the top surface of the molten steel is wavy, making it difficult to maintain a stable arc during arc heating.

■ As shown in Figure 2, the air bubbles (c) push the slag (1) around the wall, and the arc (f) is not wrapped in the slag (1) and is exposed, resulting in poor heat efficiency and Easy to cause wall damage.

(2) The bubbles (c) reach their maximum size when they reach the surface, and the maximum stirring force occurs at the surface. Therefore, molten steel (d)
There is a tendency for the slag (1) to be drawn in and reoxidized.

In refining molten steel, the most important points are to increase the stirring power of the molten steel and to easily control the temperature, but neither of these can be achieved with the conventional methods described above.

The present invention aims to perform refining and temperature control in a short time, and uses a suction-type stirring device to suck up and discharge molten steel in a ladle, and stirs it using an arc electrode. This invention relates to a method and apparatus for heating molten steel and refining molten steel.

Embodiments of the present invention will be described below with reference to the drawings.

Fig. 3 shows an embodiment of the present invention, in which a stirring device (3) (!:,
A heating device (4) that heats molten steel (2) is provided. (5
) is a ladle truck.

The stirring device (3) includes a molten steel suction pipe (6) having the same diameter from one end to the other end, and an end (6) of the molten steel suction pipe (6).
The support arm (elevating cylinder T8 connected to the force) is integrally attached to the support arm (upper end), the guide rod (9) fixed to the support arm (7), and the guide rod (9) is guided. It consists of a guide roller OQ, and the molten steel suction pipe (6) is raised and lowered obliquely via the support arm (7) by the expansion and contraction movement of the cylinder (8), and this raising and lowering is carried out by the guide rod (9) and the kite roller. α0)
A suction pipe lifting device (b) that allows for smooth operation.
and a discharge pump (not shown) for discharging the pressure inside the suction pipe (6), which is connected between the upper end of the suction pipe (6);
The recovery pipe (6), the exhaust pressure cutoff exhaust pressure valve σ frame provided in the middle of the exhaust and recovery pressure pipe @, and the recovery valve σ frame provided between the middle of the exhaust and recovery pressure pipe (6) and a waste supply source (not shown). The molten steel (2) is composed of a pressure valve α → self, and after sucking up the molten steel (2) with the molten steel suction pipe (6), the molten steel (2) is stirred by discharging it into the ladle (1). .

Further, the heating device (4) includes a plurality of electrodes (112 and
A support arm (g) that supports the electrode α0, an electrode lifting device θ that lifts and lowers the electrode a via the support arm GIG, a secondary conductor α8) for electricity supply, a power supply device (not shown), The molten steel (
2) Make it hot. Various configurations can be considered for the electrode lifting device Q, but as shown in the figure, a guide sheave (E) is attached to the lower ends of two guide rods fixed to a support frame (7), and one end is fixed. The wire rope (gl) is wound around the drum of the winch (a), and one drive of the winch (a) moves the guide rod α.
The electrode α may be moved up and down by being guided by a guide roller (A) and moved up and down.

When refining is carried out using the apparatus of the present invention having the above configuration,
Do it as follows.

Ladle (1) on ladle truck (5)? Received molten steel (
2) is set at the refining position by the ladle truck (5), the molten steel suction pipe (6) is lowered by the suction pipe lifting device 0υ, and the lower end of the suction pipe (61) is immersed in the molten steel (2). Next, the exhaust pressure pump (not shown) is started and the exhaust pressure valve α is opened.As a result, the molten steel (2) in the ladle (1) is discharged.
is sucked up by the difference between the atmospheric pressure and the pressure inside the suction pipe (6), resulting in the state shown in FIG.

Next, the exhaust pressure valve 1:13 is closed, and the pressure recovery valve α→ is opened to restore pressure in the suction pipe (6). This allows the suction pipe (6)
The molten steel that had been sucked up into the ladle (1) is discharged obliquely into the ladle (1).

The molten steel in the ladle (11) is sequentially repeated to suck up the molten steel into the molten steel suction pipe (6) and discharge the molten steel from the molten steel suction pipe (6) into the ladle (11). 2) can be stirred by rotating it in the direction of the arrow.

On the other hand, the electrode σ0 constituting the heating device (4) is lowered during stirring of the molten steel (2) to heat the molten steel (2).

The molten steel (2) is stirred and heated to refine the molten steel (2).

In the above refining method, the case where the pressure inside the molten steel suction pipe (6) is reduced and the molten steel (2) is sucked up into the molten steel suction pipe (6) has been explained. The pressure valve σ4 is connected to a pressure pump (not shown), and when the suction pipe (6) is lowered and immersed in the molten steel (2), the suction pipe (6) is ) into the ladle () by opening the pressure valve σ4 and pressurizing the inside of the suction pipe (6).
1) Either push it inward or use the pressure recovery valve α→
The molten steel (2) in the suction pipe (6) is returned to the ladle (1) by opening the suction pipe (6) to bring the pressure inside the suction pipe (6) to atmospheric pressure. (2) may be stirred. When this method is adopted, the degree of stirring of molten steel is as follows: The molten steel (2) discharged into the ladle (1) and subjected to stirring
) is determined by the initial immersion depth of the suction pipe (6) and the applied pressure.

Next, FIG. 4 shows another embodiment of the present invention.
In place of the molten steel suction pipe (6) in the device shown in the figure, the molten steel (2
) Molten steel suction pipe with a larger diameter upper part that will not be immersed in water (c)
The other configuration is the same as that shown in FIG. 6.

In this example, after the tip of the molten steel suction pipe (c) is immersed in the molten steel (2), the exhaust pressure valve α is opened, and the pressure inside the suction pipe (c) is reduced using the exhaust pressure pump. Ladle (molten steel in 11 (2)
) is sucked up by the pressure difference, then the suction pipe (C) is further lowered while the pressure inside the suction pipe (C) is reduced. As a result, the molten steel (2) corresponding to the descending height is sucked up into the larger diameter portion of the suction pipe. Next, the molten steel suction pipe (c)
The molten steel (2) in the suction pipe is discharged by raising it to the initial immersion position.

According to this embodiment, the molten steel (2) is sucked up into the larger diameter portion of the suction pipe (c), so the amount of suction increases.
It has the advantage that a large stirring effect can be obtained, and it also has the advantage that the suction pipe (C) can be drained by raising and lowering the suction pipe (C) and opening and closing the exhaust pressure valve α■ and the pressure recovery valve O→ explained in Fig. 6. By combining pressure and return pressure, the suction and discharge speeds of the molten steel (2) become faster, and the stirring effect becomes even greater.

Figures 5 and 6 show still another example, in which the ladle (11) is shaped differently so that the upper side of the ladle (11) protrudes outward in the same configuration as in Figure 6. The molten steel suction pipe (6) can be raised and lowered along the same line.The same reference numerals as in Fig. 3 indicate the same parts.

According to this embodiment, the molten steel suction pipe (6) can be placed away from the electrode QO, thereby preventing heat damage from the electrode Qυ, and when refining a small volume, the diameter of the ladle is small. Although there are cases where the suction pipe (6) and the electrode αυ cannot be arranged properly, this problem can be easily solved by making the upper part of the ladle (1) irregularly shaped as described above.

As described above, according to the present invention, the following excellent effects can be achieved.

(1) Uniform stirring allows refining without variations in ingredients, temperature, etc.

(11) Since the stirring power is large, the refining time can be shortened.

(iii) Arc heating can be easily controlled because there is little undulation on the top surface of the molten steel.

GV) Since there is no slag entrainment and the slag remains uniformly covered, it is possible to shield the arc plasma, prevent damage to the refractory, improve thermal efficiency, and prevent reoxidation.

(■) There is a slight degassing effect in the suction pipe due to reduced pressure.

[Brief explanation of the drawing]

Figures 1 and 2 are schematic diagrams showing the conventional refining method;
4 is a schematic diagram showing another example of the refining apparatus of the present invention. FIG. 5 is a schematic diagram showing still another example of the present invention. The figure is a plan view of the ladle in FIG. 5. (11 (+1... ladle, (2)... molten steel, (3)...
... Stirring device, (4) ... Heating device, (6) ... Molten steel suction pipe, 0υ ... Suction pipe lifting device, (6) ... Discharge, recovery pipe, q3 ... Exhaust pressure valve, a→...recovery valve, (a)...electrode, a'i'r...electrode lifting device.

Claims (1)

[Claims] 1) After immersing the tip of a molten steel suction pipe in molten steel to be refined and sucking up the molten steel, the molten steel is produced by discharging the molten steel from inside the suction pipe into the molten steel. A method for refining molten steel characterized by stirring the molten steel and heating the molten steel being stirred at the same time. 2) A molten steel suction pipe for sucking up molten steel in a molten steel refining container, a moving device for moving the molten steel suction pipe so that its tip is immersed in the molten steel, and an inside of the molten steel suction pipe. A stirring device comprising a valve for discharging or pressurizing the molten steel and piping connected to the molten steel suction pipe,
A molten steel refining device characterized in that it is equipped with a heating device that can be moved up and down to heat the molten steel stirred by the stirring device.