JPH08150448A - Method and device for preventing clogging of ladle nozzle - Google Patents

Abstract

PURPOSE: To prevent the clogging of a ladle nozzle with a simple device and method by fitting the device for floating-up and removing inclusions just in the front of the ladle nozzle. CONSTITUTION: An electromagnetic stirring device 1 is arranged between the sliding nozzle 6 and the ladle, and while giving the rotating movement to the molten metal with this device, inert gas 3 is blown from the wall surface of a porous plug or a slit structure gas blowing refractory 2. The inert gas 3 is formed as fine bubbles 4 is accumulated, coarsened and floated up with centrifugal force accompanied with the rotation. The molten metal near the wall surface of the gas blowing refractory 2 accompanied with the behavior of the bubbles becomes the rotation descending flow and the molten metal near the center part becomes the rotation ascending flow. A part of the suspended inclusions containing the fine inclusions in the molten metal is carried with the molten metal stream and ascended and further, caught into the bubbles 4 and floated up. In such way, the inclusions containing the fine inclusions in the molten metal is floated up and removal to prevent the clogging of the ladle nozzle. By this method, the cleaning of the molten metal can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for preventing a pot nozzle from being clogged due to adhesion of inclusions in a continuous casting method.

[0002]

2. Description of the Related Art In recent years, requirements for material properties of thin plate materials for automobiles and home appliances, and offshore structures, storage tanks, steel pipes for transporting oil and gas, high-strength wire rods and the like have become more severe. On the other hand, the development of the solidification process has been remarkable in recent years, and most of the products have been produced by the continuous casting method by this method, and the near net shape technology such as the strip casting method has been developed as a more rational production method. .

In these manufacturing processes, the molten metal is usually supplied from a pan to a tundish, which is then distributed to each mold and supplied to a solidification process. In these processes, there is a steel type in which continuous casting is difficult due to blockage of the pan nozzle. Occurrence of such nozzle blockage in the pan interferes with the residual hot water treatment in the pan and production cannot be planned, and interferes with production at the continuous casting plant. Have difficulty.

The cause of such nozzle clogging is, as shown in “Materials and Processes” 4 (1991), P. 219, due to the metal ingot caused by the cluster ring of alumina and before passing through the nozzle. It is considered necessary to clean the molten metal flowing out of the pot. As a method for cleaning the molten metal in the pot, Japanese Patent Publication No. 59-29083 proposes a method in which a rotating magnetic field is installed on the outer circumference of the container, the molten iron in the container is rotated, and inclusions are floated and separated. However, it is not economical to apply it to large-scale practical equipment of 10 tons or more because of the high equipment cost.

As a method for cleaning molten metal, Japanese Patent Publication No. 6-
According to Japanese Patent No. 47691, a rotary motion is given to a molten steel flowing in a flow pipe in a direction perpendicular to the flow to agglomerate and enlarge inclusions in the molten steel, and then a molten steel flow flowing out from the flow pipe is changed and decelerated in a container. There has been proposed a method of promoting floating of inclusions that have become bloated. In this case, the cleaning of the molten metal is promoted in a container such as a tundish after passing through a flow path such as a nozzle, and it is impossible to prevent the nozzle from being blocked.

[0006]

Therefore, in order to prevent clogging of the pan nozzle, it is an important issue to establish a simple method for separating inclusions in the molten metal before passing through the nozzle.

[0007]

The gist of the present invention is as follows. That is, (1) in the continuous casting method in which the molten metal is supplied from the pot to the solidification process, a device for floating and removing inclusions including fine inclusions is attached immediately before the pot nozzle to prevent the pot nozzle from being blocked. Continuous casting method.

(2) In the continuous casting method in which the molten metal is supplied from the ladle to the solidification step, an inert gas is blown into the molten metal from the wall surface while imparting rotary motion to the molten metal at the molten metal outflow portion of the pot.
The continuous casting method according to (1) above, characterized in that the bubbles and inclusions are accumulated in the central portion by centrifugal separation, and the inclusions are floated and removed by the rise of the bubbles to prevent nozzle clogging.

(3) Injecting an inert gas into the molten metal from the wall surface while giving rotational motion to the molten metal at the molten metal outflow portion of the pan,
A device that collects air bubbles and inclusions in the center by centrifugation and lifts and removes the inclusions by rising bubbles to prevent nozzle clogging.

[0010]

[Operation, Example] As a result of investigating the actual state of adhesion when such a nozzle blockage occurs, the inner surface of the pot nozzle is often clogged with metal, and inclusions form clusters in the metal. The present invention has been accomplished by observing that it is necessary to remove fine inclusions having a size of 10 μm or less suspended in a molten metal to prevent the nozzle clogging.

FIG. 1 is a schematic view of the present invention. As shown in FIG. 2, this apparatus is installed between a sliding nozzle 6 and a pan 9 and a magnetic plug 5 is used to rotate the molten metal while a porous plug or The inert gas 3 is blown from the furnace wall of the gas blowing refractory 2 having a slit structure. The inert gas 3 blown from the furnace wall of the refractory 2 becomes fine bubbles 4,
These fine bubbles accumulate in the center due to the centrifugal force associated with rotation.
It becomes coarse and rises. Due to the behavior of the bubbles, the molten metal in the vicinity of the furnace wall of the gas-blown refractory 2 has a rotating downward flow, and has a rotating upward flow in the vicinity of the center.

A part of suspended inclusions in the molten metal including fine inclusions floats on the molten metal flow, and is trapped by the bubbles 4 and floats together with the bubbles 4. In this way, the inclusion removing device 5
To float inclusions including fine inclusions from the molten metal.
By removing it, there is no nozzle clogging in the sliding nozzle 6 and the lower nozzle 7 of the pan, and the molten metal is passed through the long nozzle 8, the tundish 10 and the dipping nozzle 11,
It is stably supplied to the coagulation device 12. FIG. 3 shows the effect of preventing nozzle clogging of steel, which is likely to cause nozzle clogging. It can be seen that the number of nozzle clogging is eliminated by introducing this device.

[0013]

As described above, the simple equipment and method for preventing the nozzle clogging proposed in the present invention can prevent the clogging of the ladle nozzle, and enables the mass production of steel grades which are difficult to produce due to the conventional nozzle clogging. It was In addition, this method makes it possible to clean the molten metal even in steel types in which the nozzle is not clogged.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a pan nozzle blockage prevention device.

FIG. 2 is a view showing a method of mounting the pan nozzle blockage prevention device.

FIG. 3 is a view showing the effect of preventing the pan nozzle from being blocked by this method.

[Explanation of symbols]

1: Electromagnetic stirrer, 2: Gas-blown refractory (porous plug or slit structure), 3: Blown Ar gas,
4: Bubbles, 5: Inclusion remover, 6: Sliding nozzle, 7: Lower nozzle of pan, 8: Long nozzle, 9: Pan, 10: Tundish, 11: Immersion nozzle, 12: Coagulator.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location C21C 7/00 H 7/072 P (72) Inventor Kenichi Miyazawa 1 Kimitsu, Kimitsu-shi, Chiba Shin-Nihon Kimitsu Steel Works, Ltd.

Claims (3)

[Claims] 1. A continuous casting method for supplying molten metal from a ladle to a solidification step, wherein a device for floating and removing inclusions including fine inclusions is attached immediately before the pan nozzle to prevent the pan nozzle from being blocked. Method for preventing blockage of pot nozzle in continuous casting. 2. In a continuous casting method for supplying molten metal from a ladle to a solidification step, an inert gas is blown into the molten metal from a wall surface while imparting a rotational motion to the molten metal at a molten metal outflow portion of the ladle, and bubbles are generated by centrifugal separation. 2. The method for preventing clogging of a ladle nozzle in continuous casting according to claim 1, wherein the clogging of the ladle nozzle is prevented by accumulating the inclusions in the central portion and floating / removing the inclusions by rising bubbles to prevent the nozzle clogging. 3. An inert gas is blown into the molten metal from the wall surface while imparting a rotational motion to the molten metal at the molten metal outflow portion of the pot, and bubbles and inclusions are accumulated in the central portion by centrifugal separation, so that the bubbles rise. A device to prevent pan nozzle clogging by floating and removing inclusions to prevent nozzle clogging.