JP2000180069A - Method for preventing bricks from falling out of molten metal holding container - Google Patents

Abstract

(57) [Summary] (Problem corrected) [Problem] In a container in which the outer shell of a molten metal holding container such as a converter for holding a molten metal is made of iron shell, a state in which the remaining thickness of the first inner work brick is reduced. But how to prevent the work brick from falling off. SOLUTION: In a molten metal holding container 1 in which an outer shell is an iron shell 2 and at least one layer of a work brick 12 is constructed inside, a work brick is controlled by controlling the outer surface temperature of the iron shell to 400 ° C. or less. Ensure mutual abutment and prevent work bricks from falling off. At this time, it is preferable to cool the outer surface of the steel shell with air.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing bricks from falling off in a molten metal holding container in which the outer shell of a converter or the like is constructed of iron shell.

[0002]

2. Description of the Related Art Generally, a brick structure of a molten metal holding container such as a converter is a structure in which bricks of substantially the same shape are stacked along an outer shell and the held bricks are held down by a presser foot provided at the top. . For this reason, permanent bricks have a thin brick thickness and are relatively firmly fixed by holding hardware.
Work bricks are mainly held by the biasing force due to the taper between the work bricks, so the holding power is weak, and at the end of use, it falls off despite the usable remaining thickness, and the use of a molten metal holding container Reduce the number of times. For this reason, many techniques for preventing the work brick from falling off have been disclosed.

For example, Japanese Patent Application Laid-Open No. Hei 5-279719 discloses that an iron plate member is buried on the side of a work brick at a furnace port drawing portion.
A converter having a brick structure in which work bricks are connected to each other by welding the iron plate members is disclosed.
No. 152 discloses a converter having a drawn portion having a structure in which a rib is welded to the inner surface of an outer shell and a work brick is held and supported by a tension metal attached to the rib.

[0004]

However, a brick structure in which the work bricks are connected to each other by welding the above-mentioned iron plate members to a pool portion where the molten metal contacts or a portion where the molten metal contacts at the time of tapping or charging. Or, if it is constructed by a brick structure locked and supported by a tension metal, the molten metal of the iron plate member and the tension metal is melted by the molten metal, and there is a concern about serious trouble such as iron shell melting due to the insertion of the molten metal. . Furthermore, in a brick structure locked and supported by a tension metal, it is necessary to fill the gap between the work brick and the outer shell with an irregular-shaped refractory, and in this case, a dense construction body such as a brick is required. It is difficult to obtain, and there is a problem in long-term stability and construction time.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a molten metal holding container having an outer shell made of iron shell, even when the remaining thickness of the work brick is reduced. An object of the present invention is to provide a brick falling prevention method capable of preventing a work brick from falling off.

[0006]

According to the present invention, there is provided a method for preventing bricks from dropping from a molten metal holding container, wherein the outer shell is made of an iron shell, and at least one layer of work bricks is installed inside the outer shell. The invention is characterized in that the outer surface temperature of the steel shell is controlled to 400 ° C. or lower to secure the abutting force between the work bricks and prevent the work bricks from falling off. At this time, it is preferable to cool the outer surface of the steel shell with air.

The present inventors have found that in a molten metal holding container having an outer shell made of iron shell, the work brick has a remaining thickness of 100 to 1 mm.
The mechanism by which the work bricks fall off at the stage when the work bricks become thin about 50 mm was examined and examined by comparing the outer surface temperature of the side wall of the converter with the state of the bricks in the furnace.

FIG. 1 is a graph showing the results of measuring the outer surface temperature of the shell of the converter straight body from the start of use of one furnace to the end of use after work brick construction. As shown in FIG. 1, as the number of days of use elapses, that is, with the wear of the work brick, the outer surface temperature of the steel shell gradually increases, and the work brick falls off 88 days after the start of use. The permanent brick was exposed.
When the permanent brick is exposed, 3
The outer surface temperature of the iron skin was about 50 to 400 ° C and was 500 ° C
At this time, and at this time, a phenomenon in which the falling range of the work brick was expanded in the furnace was confirmed. In FIG. 1, the reason why the fluctuation width of the outer surface temperature of the shell becomes large after about 35 days has elapsed is that the furnace is operated while repairing the inside of the furnace with an irregular refractory due to wear of the work brick. Immediately after the repair of the fixed refractory, the outer surface temperature of the shell temporarily decreases, but the outer surface temperature of the shell increases again with the wear of the repair material. In addition, one furnace cost described in the present invention is a period from the start of use after the replacement with a new work brick to the end of the furnace life.

[0009] From these results, the mechanism by which the thinned work brick falls off was considered as follows. When the remaining thickness of the work brick decreases, the temperature of the steel shell rises and the steel shell expands.
It expands, and the binding force of the brick by the iron skin decreases. As a result, the abutting force between the work bricks is weakened, the work bricks are easily dropped, the joints between the work bricks are opened, the molten metal is inserted into the joints, and the work bricks are raised and dropped. When some of the work bricks fall off, the abutment between the work bricks becomes extremely weak,
Since the temperature of the steel shell rises remarkably, the work brick around the fall-off point easily falls off, and the fall-off portion expands at a stretch.

As described above, it has been found that the main cause of falling of the work brick when the remaining thickness of the work brick is reduced is an increase in the temperature of the steel shell of the molten metal holding container.

Therefore, the present inventors used a converter shown in an embodiment described later and cooled the converter straight body portion of the trunnion ring portion with air to keep the outer skin temperature of the straight shell body constant. A test run controlled to a value below the value was carried out (detailed description will be given later). Then, in each test operation, the residual thickness of the work brick when the work brick was dropped was investigated. FIG.
As shown in FIG. 3, in the test operation in which the outer surface temperature of the steel shell was controlled to 400 ° C. or less, the work brick remaining thickness at the time of falling off was 50 mm or less, as shown in FIG. On the other hand, in the test operation in which the outer surface temperature of the iron skin exceeded 400 ° C., the remaining thickness of the work brick at the time of falling off was 100 mm or more. That is, in the operation where the outer skin temperature was controlled to 400 ° C. or less, the work brick did not fall off until the outer surface temperature became 400 mm or less. Despite its thickness, it had fallen off.

On the basis of this result, the present inventors have set the outer surface temperature of the iron shell to 400 ° C. or less in a molten metal holding container in which the outer shell is an iron shell and at least one layer of work brick is constructed inside the shell. It was confirmed that, by controlling to, the binding force of the steel shell was maintained, and it was possible to prevent the work brick from falling off. At this time, by cooling the outer surface temperature of the shell using air as a cooling medium, the outer surface temperature of the shell can be easily and inexpensively controlled.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 2 is a schematic front view of a converter according to an embodiment of the present invention.

In FIG. 1, a converter 1 has an outer shell
The inside of the steel shell 2 is constructed of two layers of refractories in the order of the permanent brick 11 and the work brick 12, and a plurality of stoppers 6 provided on the outer periphery of the steel shell 2 are provided on the straight body of the converter 1. Ring 3 sandwiched between a plurality of stoppers 7
Is installed. In this trunnion ring 3, two trunnion shafts 4 are installed outward on a straight line passing through the center point of the trunnion ring 3, and the two trunnion shafts 4 are supported by bearings 5, respectively. The furnace 1 is rotatable around a trunnion shaft 4.

A gap 10 between the iron shell 2 and the trunnion ring 3
Is provided with a pipe 8 circling the steel shell 2 along the inner periphery of the trunnion ring 3, and the pipe 8 is connected to a flow path 9 penetrating the trunnion shaft 4 in the axial direction thereof, Further, the pipe 8 is provided with a plurality of pores (not shown) toward the steel shell 2, and the air supplied into the flow path 9 is blown to the steel shell 2 through the pipe 8, Leather 2
It has a structure to cool. A plurality of thermocouples (not shown) are provided in a portion of the steel shell 2 cooled by air in a circumferential direction of the steel shell 2 to measure an outer surface temperature of the steel shell 2.

Then, during the operation of the converter 1, the outer surface temperature of the shell 2 is measured, and the outer surface temperature of the shell 2 is controlled to 400 ° C. or less. Specifically, the steel shell 2 is cooled while controlling the amount of air or the air pressure supplied to the flow path 9 so that the outer surface temperature of the steel shell 2 does not exceed 400 ° C. Set the outer surface temperature of steel
The amount of air and the air pressure for keeping the temperature below 00 ° C. are determined by the material and thickness of the permanent brick 11 and the work brick 12 applied to the converter 2, the part of the converter 1, the furnace volume of the converter 1, and the converter 1. It is preferable that the air amount and the air pressure be changed beforehand for the investigation, since it changes depending on the operating conditions of the air conditioner.

By controlling the outer surface temperature of the steel shell 2 in this manner, the restraining force of the steel shell 2 on the work bricks 12 is maintained. The work brick 12 can be prevented from falling off even when the work brick 12 is thin.

In the above description, the case where one pipe 8 is installed in the straight body is described. However, the present invention is not limited to this. For example, the pipe 8 may be provided in each part of the furnace bottom, the straight body, and the throttle. The pipes 8 may be installed individually, or a plurality of pipes 8 may be installed at each part. Further, the means for supplying cooling air is not limited to the pipe 8, and individual nozzles may be provided at each part. Further, the cooling medium is not limited to air, and a pipe may be closely mounted on the outer surface of the steel shell 2 and the steel shell 2 may be cooled by passing cooling water through the pipe. In short, it is necessary to cool the outer surface temperature of the steel shell at a portion where the work brick 12 is to be prevented from falling off and control it to 400 ° C. or less. Further, the application of the present invention is not limited to the converter 1. The converter type smelting reduction furnace, which is a molten metal holding vessel having an outer shell of iron shell, a vacuum tank of an RH vacuum degassing apparatus, a mixed iron wheel, and It is also applicable to pots and the like.

[0019]

EXAMPLE Using the converter shown in FIG. 2, a test operation was carried out in which the relationship between the outer surface temperature of the steel shell of the steel shell body and the state of falling off work bricks was controlled while controlling the outer surface temperature of the steel shell to a certain value or less. The furnace volume of the converter used was 250 tons, and the permanent brick was MgO-Cr2O.
3 Use a brick to a thickness of 150 mm.
The thickness was 900 mm using gO-C brick. A pipe for supplying cooling air had an inner diameter of 20 mm. A hole having a diameter of 2 mm was formed in the pipe, and air was flown at a pressure of 6 kg / cm 2 to blow the steel shell to cool it.

Then, the temperature of the outer surface of the skin of the straight body is set to 350
Below 360 ° C, below 360 ° C, below 380 ° C, below 380 ° C,
395 ° C or less, 400 ° C or less, 420 ° C or less, 430 ° C
440 ° C or less, 450 ° C or less, 460 ° C or less,
Thirteen levels of test runs controlled at 70 ° C or lower and 480 ° C or lower were performed. The meaning of controlling the outer surface temperature of the iron shell to 350 ° C. or less means that the maximum value of the outer surface temperature of the iron shell is 350 ° C. during the period from the start of use after the refractory construction to the falling of the work brick. is there.

In each test operation, the inside of the furnace is inspected at the time of tapping to check whether or not the work bricks in the straight body have fallen off. When the work bricks fall off, the work bricks at the time when the work bricks fall off are checked. The remaining thickness was measured by collecting the dropped work brick or the work brick around the dropped part. FIG. 3 shows the results of the investigation in each test operation. The horizontal axis in FIG. 3 shows the maximum value of the outer surface temperature of the steel in each test operation.

As shown in FIG.
In the test operation controlled at 0 ° C. or less, the remaining thickness of the work brick at the time of falling was 50 mm or less, and it was possible to prevent the falling of the work brick until the remaining thickness was almost equal to the working limit of the work brick. . On the other hand, in the test operation in which the outer surface temperature of the iron skin exceeded 400 ° C., the remaining thickness of the work brick at the time of falling off was 100 mm or more, and the work brick could not be used to near the use limit.

In a test operation in which the outer surface temperature of the steel skin is controlled to 400 ° C. or less, the life of the furnace body can be improved by about 20% as compared with a test operation in which the temperature exceeds 400 ° C. The amount of irregularly shaped refractory for repair used in the furnace cost was significantly reduced.

[0024]

According to the present invention, the binding force on the work brick by the steel shell is maintained, and even when the work brick becomes thin, the work brick can be prevented from falling off.
As a result, it becomes possible to extend the life of the molten metal holding container, and to greatly reduce the amount of irregularly shaped refractory used for repair due to the exposure of the permanent brick, thereby significantly increasing the cost of refractory. Reduction has been achieved, and the industrial effect is outstanding.

[Brief description of the drawings]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a view showing a measurement result of an outer surface temperature of a shell of a converter straight body portion of one furnace cost.

FIG. 2 is a schematic front view of a converter as an example of an embodiment of the present invention.

FIG. 3 is a diagram showing the results of an investigation of the relationship between the outer surface temperature of a steel shell and the remaining thickness of a work brick when dropped in the example.

[Explanation of symbols]

 Reference Signs List 1 converter 2 steel shell 3 trunnion ring 4 trunnion shaft 5 bearing 6 stopper 7 stopper 8 pipe 9 flow path 10 gap 11 permanent brick 12 work brick

Continued on the front page (72) Inventor Akihiko Inoue 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Manabu Tano 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Stock F term in the company (reference) 4K002 AA01 BB03 BC10 4K051 AA02 AB03 HA16 HA18

Claims (2)

[Claims] In a molten metal holding container in which an outer shell is made of an iron shell and at least one layer of a work brick is constructed inside the shell, the outer surface temperature of the iron shell is controlled to 400 ° C. or less, and the work bricks are mutually separated. A method for preventing bricks from falling out of a molten metal holding container, characterized by securing abutment force and preventing work bricks from falling off. 2. The method according to claim 1, wherein the outer surface of the steel shell is cooled by air.