JPH11320080A - Thermally insulated ladle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermally insulated ladle which is decreased in heat dissipation quantity from molten metal and for which a backup lining is expected as a permanent lining. SOLUTION: The lining of the ladle for molten metal comprising a metallic cylindrical casing 1 and the lining applied on its inner side has a graphite crucible constituting the innermost layer in direct contact with the molten metal and the backup lining of this graphite crucible 9. A thermally insulating material layer 8 is interposed into the boundary between the graphite crucible 9 and the backup lining.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating ladle used for receiving various types of molten metal in a foundry.

[0002]

2. Description of the Related Art Ladles generally used in cast iron factories are of a type in which a refractory material is lined in a steel plate casing, and the lining is made of a refractory brick, castable, ramming material, etc. on the inner side in contact with the molten metal. High-temperature corrosion-resistant refractory material and heat insulating material on the outside.

In the ladle having such a lining configuration, the molten metal received from the melting furnace or the forehearth has a temperature drop of about 100 ° C. in about 10 minutes to be supplied to the production line. For this reason, it is necessary to tap water at a temperature 100 ° C. higher than the casting temperature required in the production line, and a melting furnace such as a cupola requires a more severe operation, and has many problems. Therefore, the idea of strengthening the insulation of the ladle lining and coping with the drop of the molten metal temperature has come up.

[0004] However, in the lining configuration which has been conventionally employed, when the heat insulation is strengthened, there arises a problem that the interface temperature between the refractory material and the heat insulating material rises and the average use temperature of the refractory material rises. The risk of molten iron was increased, and the molten iron was inserted into the joints of the bricks and cracks in the lining, increasing the risk of leaking iron.

[0005] In addition, general refractory materials have a large amount of base metal attached due to the problem of wettability of the hot metal, and peeling damage of the refractory materials generated upon removal is not negligible.

While such damage is minor, repair can be performed temporarily by patching or the like. However, as the damage progresses, the entire lining needs to be replaced. The frequency of full replacement is quite intense.

In consideration of such damage and easy repair, the innermost layer of the lining in contact with the molten metal is made of high alumina,
The idea of using a white crucible made of silica or the like has emerged. The white crucible is a homogeneous and high-quality crucible that is integrally molded or cast at high pressure and then dried or fired, and is set by filling a dry material such as sand in a gap on the back side.

The advantages of this method are that the use of a white crucible prolongs the service life, and that if crucible occurs, only the crucible needs to be replaced. Certainly, this type of system showed signs of improvement compared to the conventional method, but cracks occurred frequently as the frequency of use of white crucibles overlapped, and the filled dry material and heat insulating material were replaced when replacing the ladle. It was still not enough to fulfill the role of permanent lining, such as requiring extraordinary construction each time.

[0009]

Originally, the purpose of enhancing the heat insulation of the ladle is to prevent the temperature of the molten metal from lowering from the viewpoint of energy saving. The strength is reduced, the wear is severe, and the life is remarkably reduced.

It is an object of the present invention to provide a heat insulating ladle which can solve the problem of the shortening of the lining life caused by the strengthening of the heat insulation.

[0011]

According to the present invention, there is provided a ladle for molten metal comprising a metal tubular casing and a lining installed inside the metallic casing, wherein the lining constitutes an innermost layer directly in contact with the molten metal. And a backup lining of the graphite crucible, wherein a heat insulating material layer is interposed at an interface between the graphite crucible and the backup lining.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a longitudinal section of the most commonly used ladle conventionally used. In the figure, 1 indicates a cylindrical casing made of a steel sheet, 2 indicates a heat insulating brick layer, and 3 indicates a high-temperature corrosion-resistant refractory brick layer made of a refractory brick, castable, ramming material or the like.

FIG. 2 shows a longitudinal section of the improved ladle of FIG. In the figure, 1 is a cylindrical casing made of a steel plate, 2 is a heat insulating brick layer, 4 is a backup lining by filling with dry ramming material or the like, and 6 is a white crucible.

FIG. 3 shows a longitudinal section of an insulated ladle according to the invention.

In the figure, reference numeral 1 denotes a cylindrical casing made of a steel plate;
Is the insulating brick layer, 7 is the backup lining, 9
Denotes a graphite crucible, and 8 denotes a heat insulating material layer interposed at the interface between the graphite crucible 9 and the backup lining 7.

In the present invention, the backup lining 7 is made of a castable refractory, a plastic refractory, a refractory brick or the like.

The graphite crucible 9 is not particularly limited as long as it is made of graphite, but a graphite crucible obtained by integrally molding under high pressure and then firing at high temperature is particularly preferable because it is homogeneous and of high quality.

The heat insulating material layer 8 is made of a heat insulating material such as a ceramic fiber felt, a board and other dry materials and mortar.

Hereinafter, a specific method of use will be described with reference to FIGS.

In the conventional ladle shown in FIG.
First, a heat-insulating refractory material 2, for example, a heat-insulating brick or a fire-resistant heat-insulating brick, and then a fire-resistant brick 3 are constructed. When castable or ramming materials are used instead of refractory bricks, they must be demolded and heated and dewatered after using a formwork.

Prior to receiving the hot water, it is preheated to 500 to 800 ° C., then received from a cupola or the like and transported to a production line.
In the molten metal, much heat is taken by the lining due to heat conduction.
A temperature drop of about 100 ° C. occurs in 0 minutes.

Increasing the thickness of the heat-insulating layer in order to enhance the heat insulation means reducing the capacity of the ladle, and further causing damage to the lining due to an increase in the interface temperature.

In the improved ladle shown in FIG.
A heat insulating refractory material layer 2 is formed inside the inside, a white crucible 6 is set therein, and a gap between the white crucible 6 and the refractory material layer 2 is filled with a dry material such as sand. Is fixed.

Although this improved type was improved by the use of the white crucible 6, cracks were frequently generated in the crucible 6 due to repetition of heat history, and the dry material filled layer 4 served as a barrier against infiltration of hot metal. Therefore, the ladle lining of the heat-insulating refractory layer 2 or the like cannot always be expected as permanent lining.

In the heat insulating ladle of the present invention shown in FIG. 3, after the heat insulating refractory material 2 is installed inside the casing 1, first,
The graphite crucible 9 whose outer surface is covered with the heat insulating material layer 8 is set correctly at a position in the ladle, and for example, a castable refractory is constructed as a backup lining 7 in a gap between the heat insulating material 2 and the heat insulating material 2. When the backup lining 7 is cured, the crucible 9 covered with the heat insulating material layer 8 is taken out, and the lining 7 is heated to remove moisture, and then the crucible 9 is set again.

The heat insulating ladle of the present invention is more insulated than the conventional product by the heat insulating refractory material 2 and the heat insulating material layer 8, and the amount of heat radiated from the molten metal is reduced, thereby preventing the temperature of the molten metal from lowering. .

On the other hand, on the other hand, the interface temperature of each layer rises, which is not a good condition for refractories. However, the graphite crucible 9 has a very high hot strength, as can be seen from the results of a graphite refractory casting factory. Since the hot metal erosion and cracking are less likely to occur, the life is extended and the hot metal is not inserted into the backup lining 7, so that the lining 7 is hardly damaged and can be used repeatedly. It can fully serve as a lining.

Hereinafter, the present invention will be described in more detail based on comparative tests and the like.

An object of the present invention is to prevent the temperature of a molten metal from lowering during transportation due to the use of a high heat insulation ladle.

Ladles that have been used in the past are usually 500-
After being preheated to 800 ° C, it is received from a melting furnace or forehearth and transported to a production line through a molten metal treatment plant.
At 0 minutes, a drop in the melt temperature of about 100 ° C. occurs. This temperature drop is caused by heat dissipation from the surface of the molten metal and loss of the furnace wall of the ladle lining. The former is improved by installing a lid on the ladle, and the latter is generally improved by strengthening the insulation of the lining.

The effect of using the ladle according to the present invention in which a graphite crucible is used as the innermost layer of the lining in contact with the molten metal in accordance with the heat insulation enhancement of the lining is as follows.

[0033] 1. 1. Prevention of drop in molten metal temperature 2. Prevent adhesion of slabs, etc. 3. Extension of life. 4. Ease of construction Reducing the number of repair days The temperature distribution in the conventional lining and the insulation lining according to the present invention are calculated assuming that the temperature distribution in the lining is in a steady state in order to simplify the comparison, as shown in FIG. become.

From the above calculations, the lining configuration of the present invention saves about 60% of the heat dissipated compared to the conventional lining configuration.

For reference, when a conventional ladle and the ladle according to the present invention were used and the temperature was reduced, the following results were obtained. The capacity of the ladle used was for 500 kg, and the lining configuration is as shown in FIG.

In the experiment, the ladle was first heated from above by a burner, heated at a rate of 10 ° C./min until the temperature in the ladle reached 800 ° C., and then held at 800 ° C. for 30 minutes. After removal, hot metal at 1500 ° C
The hot metal temperature was measured after standing for 10 minutes on a kg hot water.

Measurement Results Ladle Top Covered with a steel plate lid: 45 ° C. Ladle top open: 68 ° C. For reference, the conventional ladle was operated under the same conditions as in the above experiment. Was 103 ° C. From these experiments, the use effect of the ladle of the present invention became clear.

Next, in the lining of the conventional ladle, slag and metal are adhered near the upper part of the lining to reduce the diameter or reduce the capacity, so that it is necessary to remove them. However, since the slag reacts with the lining and adheres firmly, the lining is seriously damaged during removal. On the other hand, in the ladle lining of the present invention, a graphite crucible is used as the innermost layer in contact with the molten metal, so that adhesion of slag and the like can be prevented.

As is well known, graphite-based refractories have a very high strength at high temperatures and are hardly wetted by the molten metal. Therefore, the molten metal does not penetrate into the refractory, and spalling resistance is higher than that of any other refractory. It has many remarkable characteristics such as being superior in sex. Therefore, the graphite crucible excels in corrosion resistance to hot metal and has a longer life than any conventional high-temperature refractory.

Since the durability of the graphite crucible is extremely high, the hot metal does not enter the back of the crucible, and the backup lining can be used as a permanent lining for many years. As a result of various studies, it is expected that permanent lining will need to be replaced once or twice a year, and the life of the ladle can be dramatically extended as compared with the conventional ladle lining.

A further effect of the ladle lining of the present invention is ease of construction. Since the graphite crucible in contact with the molten metal is set as an integral product inside the backup lining via ceramic fibers, the crucible can be taken out regardless of the backup lining. That is,
In this ladle, repair can be performed by a simple operation of simply replacing the crucible.

FIG. 5 shows the repair procedure of the conventional ladle and the ladle lining of the present invention. As is clear from FIG. 5, the conventional ladle requires six steps of work, and the repair requires three to four days, whereas the ladle of the present invention requires only three days to complete the work. .

[0043]

According to the present invention, it is possible to prevent the temperature of a molten metal from dropping,
It is possible to provide a high-quality, high-performance insulated ladle capable of preventing adhesion of slag and the like, extending the life, facilitating construction, and shortening the number of repair days.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing a conventional ladle.

FIG. 2 is a longitudinal sectional view schematically showing the improved ladle of FIG.

FIG. 3 is a longitudinal sectional view schematically showing a heat insulating ladle according to the present invention.

FIG. 4 is a diagram showing a comparison between the temperature distribution and the amount of heat dissipated in the lining of the conventional configuration and the adiabatic lining of the present invention.

FIG. 5 is a view showing a repair procedure of the conventional ladle and the ladle lining of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 casing 2 heat insulating brick layer 3 fire brick layer 4 dry material filling layer 6 white crucible 7 backup lining 8 heat insulating material layer 9 graphite crucible

Claims (1)

[Claims] 1. A ladle for molten metal comprising a metal cylindrical casing and a lining installed inside the metal casing,
The lining includes a graphite crucible that constitutes the innermost layer directly in contact with the molten metal, and a backup lining of the graphite crucible, and at an interface between the graphite crucible and the backup lining,
An insulating ladle having a heat insulating material layer interposed therebetween.