JPH04173915A - Refining method with gas blowing nozzle of molten metal vessel - Google Patents

Abstract

PURPOSE:To easily and safely execute gas blowing for a long time by setting gas blowing nozzles and also blind nozzles whose number is integer times that of the gas blowing nozzles and if necessary, fitting the new gas blowing nozzle after drawing out the blind nozzle. CONSTITUTION:At the furnace bottom part 2 in a molten metal vessel 1 of electric furnace, etc., refractory bricks 3 are laid in concentric circular state and at the intermediate part thereof, slender gas blowing nozzles 4 are arranged to fit to tuyere bricks 5. By blowing the inert gas into the vessel 1 from this gas blowing nozzles 4 through a gas introducing pipe 6, refining is executed to the molten metal. At a little outside of the gas blowing nozzle 4 in the bottom part 2 in the above furnace, the blind nozzles 7 whose number is integer times that of the gas blowing nozzles 4 are set through the tuyere bricks 8. When the gas blowing nozzle 4 reaches the limit of service life, the gas blowing is stopped. Successively, the blind nozzle 7 near this is drawn out through a pipe 9 for drawing out and the fresh gas blowing nozzle is fitted to this. By this method, the gas blowing is executed for a long time and the refining efficiency is improved and the service life of the vessel 1 can be drastically improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a refining method using a gas injection nozzle in a molten metal container such as an electric furnace.

Conventional technology In recent years, a refining gas injection nozzle is placed at the bottom of a top-bottom blowing converter, electric furnace, etc. in the steelmaking process, and oxygen, CO1CO□, hydrocarbons, inert gas, etc. are blown from the gas injection nozzle. The molten metal is forcibly stirred by
It has a refining effect.

However, when refining gas is injected as described above, as the usage time passes, the gas injection nozzle and the refractories around it become severely worn out due to forced stirring of molten steel and slag. The life of the nozzle determines the life of the entire molten metal container. In order to extend the life of the molten metal container, a method of stopping the operation of the smelting furnace at this stage and replacing the gas injection nozzle and surrounding tuyere bricks was proposed, for example, as in Utility Model Application No. 186293/1983. has been done.

Problems to be Solved by the Invention However, the task of replacing the gas injection nozzle requires 8 to 48 hours due to hot work in the furnace, and is not a desirable task in terms of safety and health.

Additionally, if only the gas injection nozzle is replaced at the same location, the new gas injection nozzle will protrude due to damage to the surrounding refractories and be easily damaged by thermal spalling. The life of the nozzle was significantly reduced, making it impossible to blow gas for a long time.

Means for Solving the Problems The present invention has been made in view of the above-mentioned points, and in order to solve the above-mentioned problems, a gas blowing nozzle is arranged at the bottom of a molten metal container such as an electric furnace. , blind nozzles that do not inject gas are placed at the bottom of the furnace in a number that is more than an integral multiple of the number of gas injection nozzles, and when the gas injection nozzles reach the end of their service life, the gas injection of the gas injection nozzles is stopped and the blind nozzles are removed. To provide a method for refining a molten metal container using a gas blowing nozzle, which is characterized in that a new gas blowing nozzle is installed in a molten metal container and a refining gas is blown thereinto.

According to the present invention, by arranging the gas blowing nozzle and the blind nozzle that does not blow gas at the bottom of the furnace of the molten metal container, the gas blowing nozzle reaches the end of its life. At this time, the blind nozzle that does not inject gas can be removed from the bottom of the furnace and a new gas injecting nozzle can be installed to continue injecting gas.

Therefore, gas injection can be performed for a long time, improving the refining effect of molten metal, and the life of the molten metal container can be significantly extended.

Example Hereinafter, the present invention will be explained based on examples.

FIG. 1 and subsequent figures show an embodiment of the present invention. The furnace bottom 2 of the molten metal container 1 of the electric furnace is constructed with refractory bricks 3 concentrically as shown in Figs. Three nozzles 4 are attached to tuyere bricks 5 and arranged axially symmetrically at intervals of 120 degrees. Then, a necessary gas supply device (not shown) is connected to the gas introduction pipe 6 protruding from the lower end side of the gas blowing nozzle 4, and N2
, A, etc. can be injected.

At the slightly outer side of the furnace bottom 2 where the gas blowing nozzle 4 is attached, there is a 6
Blind nozzles 7 are arranged axially symmetrically through tuyere bricks 8. The blind nozzle 7 has the same shape as the gas blowing nozzle 4, and is a durable blind plug that does not blow gas. Further, the tuyere brick 8 of the blind nozzle 7 has the same shape as the tuyere brick 5 of the gas blowing nozzle 4, so that they are compatible and can be used in common. Although gas is not blown into the blind nozzle 7, a removal pipe 9 is attached to it in the same way as the gas introduction pipe 6 so that it can be pulled out downward.

As shown in FIG. 3, a cylindrical body 11 for attaching and removing the nozzle is attached to the outer shell 10 on the outer periphery of the furnace bottom 2, and flanges 12 and 13 are superimposed on the ends of this cylindrical body 11. It is joined like this. Then, by removing this flange 13, the blind nozzle 7 is pulled out by pulling the pipe 9 for removing the blind nozzle 7 with a pulling device (not shown) such as a hydraulic jack, and then the blind nozzle 7 is pulled out using an insertion device (not shown). This makes it possible to insert a new gas blowing nozzle.

Then, gas is blown into the molten metal container 1 from the gas blowing nozzles 4, and when each melts and wears out as shown in Fig. 4 and reaches the end of its life, the gas blowing from these gas blowing nozzles 4 is stopped. . Then, remove the blind nozzle 7 on either the left or right side near these gas injection nozzles 4 as described above, insert a new gas injection nozzle, and continue gas injection. It is something.

If the replaced gas injection nozzle becomes damaged again as shown in Fig. 4, the remaining blind nozzle 7 is removed and a new gas injection nozzle is inserted to perform gas injection. .

In addition, since the blind nozzle and the gas blowing nozzle can be replaced outside the furnace, the hot work can be significantly reduced and the gas blowing nozzle can be replaced in a short time.

FIG. 5 illustrates the relationship between the number of cuts and the remaining amount of hearth bricks in the above case.

As can be seen from the figure, in the conventional method of gas injection, 4
However, with the present invention, by installing a new gas injection nozzle twice every approximately 330 times, the gas injection can be extended to a total of 960 times. , gas can be injected for about 2.4 times longer than conventional methods, and the life of the furnace can be greatly improved.

As can be seen from FIG. 5, it is possible to install the gas blowing nozzles one more time, and it can be determined that the number of blind nozzles is preferably double or triple the number of the original gas blowing nozzles. However, even if it is replaced only once, a considerable effect is produced.

In the example, three gas injection nozzles were arranged, but an appropriate number can be arranged depending on the operating conditions of the molten metal container and the furnace repair period. Although it is best to keep the electric furnace in the
The present invention can be similarly applied to other molten metal containers.

Effects of the Invention As described above, in the present invention, when the gas blowing nozzle is eroded and reaches the end of its service life, gas blowing is continued by removing the blind nozzle and replacing it with a new gas blowing nozzle. This allows gas injection to be carried out over a long period of time, thereby improving the refining effect of the molten metal.

Furthermore, since gas can be blown in from a new gas injection nozzle at the position of the blind nozzle for refining, the life of the molten metal container can be significantly extended, and the cost of refractory materials can be reduced.

[Brief explanation of drawings]

1 and 2 are a partially omitted plan sectional view and side sectional view of a molten metal container according to an embodiment of the present invention, FIG. 3 is a side sectional view of the mounting portion of the blind nozzle, and The figure is a cross-sectional view for explaining the melted state of the gas injection nozzle portion same as above, and FIG. DESCRIPTION OF SYMBOLS 1... Molten metal container, 2... Furnace bottom, 4... Gas blowing nozzle, 7... Blind nozzle. Applicant: Kawasaki Rozai Co., Ltd. Figure 1 Figure 3 Figure 4 Figure 5 Number of furnaces (times)

Claims (1)

[Claims] (1) A gas blowing nozzle is placed at the bottom of the molten metal container such as an electric furnace, and blind nozzles that do not blow gas are placed at the bottom of the furnace in numbers equal to or more than an integral multiple of the gas blowing nozzles. Gas blowing into a molten metal container characterized by stopping gas blowing from the gas blowing nozzle when the nozzle reaches the end of its life, removing the blind nozzle, installing a new gas blowing nozzle, and blowing refining gas into the vessel. Refining method using a nozzle.