JPH11320079A - Crucible furnace type ladle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crucible furnace type ladle capable of transporting molten metal received therein to a production line with substantially no lowering of the temp. of the molten metal. SOLUTION: This crucible furnace type ladle has a ladle body installed with a graphite crucible in a cylindrical vessel internally lined with refractory material in a metallic casing 2, a cap back lined with the refractory material within a metallic flask 13 of a size to cover approximately the entire area of the front surface of the ladle body and burners 8 for combustion mounted at the ladle body and the cap. At the time of use, the graphite crucible installed in the ladle may be heated from both inner and outer surface sides by these burners for combustion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crucible furnace ladle for transferring molten metal discharged from a melting furnace, a forehearth or the like to a production line in a foundry.

[0002]

2. Description of the Related Art In a foundry, a molten metal discharged from a melting furnace and a forehearth into a ladle is transferred to a molten metal processing plant, where molten metal processing such as slag removal, desulfurization, and degassing is performed. To be served.

The ladle used here is of a system in which a refractory material is lined in a cylindrical steel container. When a ladle of this type is used, the temperature of the molten metal is large, for example, about 100 ° C., during a required time of about 10 minutes from receiving the molten metal in the melting furnace and the forehearth to the production line.

[0004] The main causes of this temperature drop are the heat loss from the surface of the molten metal and the heat loss relating to the lining. The former is said to be 50 to 70% of the total heat loss, and the latter is said to be 30 to 50%. Here, the heat loss from the surface of the molten metal is the heat dissipated by radiation and convection, and the heat loss relating to the lining is the heat storage of the lining and the heat dissipated from the ladle surface.

In order to reduce such heat loss, it is effective to use a lid on the upper surface of the ladle for the former, and to take measures to enhance heat insulation for the latter.

[0006] However, the use of ladle lids is currently rarely used. The main reasons are as follows.

[0007] 1. It takes time to attach and detach the cover.

[0008] 2. A conventional simple type in which castable or ceramic fibers are applied to the inner surface of a steel sheet metal frame is not practical because of large distortion of hardware.

3. Strongly manufactured metal frame covers are heavy and extremely poor in workability.

[0010] On the other hand, the heat insulation reinforcement of the lining has been carried out from the early stage of the energy saving movement, but is considered to be at the limit at present. Therefore, as long as the current ladle method is employed, a large temperature drop, for example, about 100 ° C., during the transfer of the molten metal from the hot water to the production line cannot be avoided.

Assuming that the temperature of the molten metal required for the operation of the casting line is 1400 ° C., the temperature of the molten metal from the melting furnace or the forehearth must be 1500 ° C. in consideration of the above temperature drop. The temperature of the molten metal at 1400 ° C in the high
Elevating the tapping temperature to 0 ° C requires a very large amount of energy, and the lining of the melting furnace is subjected to very severe operating conditions to maintain this temperature, so that the quality of the higher-grade lining is higher. Required. That is, 1
Excessive operating costs are required to obtain a 500 ° C. melt.

[0012]

In the ladle currently used in the cast iron industry, the temperature drop during the transfer of the molten metal is large, and the temperature of the molten metal required by the production line is, for example, one more.
It is necessary to secure a tapping temperature as high as about 00 ° C.
Therefore, it is a major problem in the industry to solve the problem of how to prevent the temperature of the molten metal during transportation from lowering and to reduce the temperature of the molten metal from the melting furnace or the forehearth.

An object of the present invention is to provide a crucible furnace-type ladle which can solve the above-mentioned problem of lowering the molten metal temperature by the conventional ladle and can easily perform the operation and reliably prevent the temperature drop. .

[0014]

A crucible furnace type ladle according to the present invention has a sufficiently large graphite crucible installed and fixed inside a ladle substantially similar to a conventional ladle, and is attached to and detached from the upper surface of the ladle. Or a lid that can be opened and closed is installed.

A combustion burner is mounted on each of the side surface of the ladle and the upper surface of the lid, so that the graphite crucible can be heated from both inside and outside. When the temperature of the graphite crucible reaches a predetermined temperature, the cover is opened to receive hot water, then the cover is closed, and then the burner is removed, transported to a predetermined position, and supplied to the production line.

According to the crucible furnace type ladle of the present invention, it is possible to transport the received molten metal without lowering the temperature and to provide the molten metal to a production line.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a crucible furnace type ladle according to 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 for transporting molten metal.

The ladle 1 comprises a cylindrical casing 2 made of a steel plate and a lining 3 lined on the inside thereof. A molten metal 4 is stored inside the ladle, and the ladle is provided with a suspension device 5.

FIG. 2 shows a cross section of a crucible furnace type ladle according to the present invention.

The crucible furnace type ladle according to the present invention comprises a ladle 1, a lid 1
2 and the main parts of the combustion burners 8 and 15. The ladle 1 comprises a cylindrical casing 2 made of a steel plate and a lining 3 lined with a heat insulating material and a refractory material inside thereof. A graphite crucible 6 is installed and fixed on a base 7 inside. The lid 12 has a refractory material 14 lined on the inner surface of a metal frame 13 assembled from a steel plate or the like. Ladle 1 side and lid 12
Burners 8 and 15 for combustion are detachably mounted on the upper surface, respectively. Valves 9 and 16 for combustion air and valves 10 and 17 for fuel gas are incorporated in the burners 8 and 15 in the piping.

The crucible furnace type ladle is provided with a suspending device 5, which can be lifted by a hoist or a crane for transfer.

Hereinafter, a specific usage of the crucible furnace type ladle according to the present invention will be described. In a foundry, a ladle is used to transport hot metal from a cupola or forehearth to a production line.

The ladle 1 shown in FIG. 1 has the most general structure. Prior to receiving hot metal from a cupola, a forehearth, or the like, a lining 3 in the ladle is provided by a combustion burner from above the ladle. Is heated, and when the temperature reaches 500 to 800 ° C., the hot water is received and transported to a production line.

In the ladle, the lid is not generally used and the surface of the molten metal is in an open state. However, since the heat dissipation from the surface of the molten metal is proportional to the temperature of the molten metal and the surface area of the molten metal, the heat loss is extremely large, and the lining 3 is preheated. However, since the flow of heat is in an unsteady state, and the molten metal 4 received in the ladle 1 is directly in contact with the lining 3, the transfer of heat from the molten metal 4 to the lining 3 is also performed by conduction heat transfer. It will be extremely large. For this reason, the heat lost from the molten metal 4 is large, and a temperature drop of about 100 ° C. occurs during the transfer for about 10 minutes.

On the other hand, the crucible furnace type ladle of the present invention shown in FIG. 2 incorporates a graphite crucible 6 for storing the molten metal 4 inside the ladle 1, and further has a lid on the upper part of the ladle 1. 12 are loaded.

In the crucible type ladle according to the present invention, the burners 8 and 15 are attached to the side surface of the ladle body 1 and the upper surface of the lid 12 prior to receiving hot water, and then the valves 9 and 16 for combustion air, the valves 10 for fuel gas and Open 17 and ignite. When the crucible 6 is heated from both inside and outside and reaches a predetermined temperature, for example, 1300 ° C., the combustion air valves 9 and 16 and the fuel gas valves 10 and 17 are closed to extinguish the fire, and the burners 8 and 15 are placed on the side of the ladle body 1. And taken out from the upper surface of the cover 12.
The crucible 6 is made of a graphite refractory, and can sufficiently withstand high-temperature heating of 1300 ° C. or more.

Next, after the lid 12 is opened and hot water is received from the melting furnace or the forehearth, the lid 12 is closed again, the ladle is lifted using the suspending device 5, and the ladle is transported to the production line through the molten metal processing plant. Then, the hot water is discharged with the lid 12 loaded on the ladle 1.

When the lid 12 is heavy and it is difficult to open and close it manually, an automatic opening and closing system may be used.

By using the crucible furnace type ladle according to the present invention, the temperature drop of the molten metal during transportation can be minimized.

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, the melt temperature drops by about 100 ° C.

As described above, the cause of this temperature drop is heat dissipation from the surface of the molten metal and loss of the furnace wall of the ladle lining.

In the crucible furnace type ladle of the present invention, the lid 12
Is provided, so that the heat dissipation from the surface of the molten metal is about 80 to 90 in comparison with a conventional ladle without a lid.
% Can be saved.

Next, the furnace wall loss of the ladle is the amount of stored heat and the heat dissipation from the ladle surface. Since the molten metal is in direct contact with the lining in the ladle, a large amount of heat is transferred by heat conduction. Ladle lining heat capacity (weight x specific heat x temperature)
Is so large that the molten metal is deprived of a large amount of heat and its temperature drops.

Therefore, it is desirable to heat the ladle to as high a temperature as possible, but it is difficult with the prior art, and the ladle is currently in the range of 500 to 800 ° C. In order to solve this problem, there is a method in which a lining temperature is increased by putting a molten metal at 1500 ° C. into a ladle heated to 500 to 800 ° C., and this molten metal is discarded. Absent.

On the other hand, according to the crucible-type ladle of the present invention, the graphite crucible 6 can be heated by the burners 8, 15 from both inside and outside surfaces. By heating, for example, 130
If the hot water is received after heating to 0 ° C. or more, the heat capacity of the crucible 6 is 1/10 of that of the conventional ladle lining.
The amount of heat lost by the molten metal is very small.

In the crucible, the temperature of the molten metal immediately becomes equal to the temperature of the molten metal upon receiving the hot water. However, the heat transfer from the crucible surface to the lining is performed by radiation and convection due to the presence of the combustion chamber space, and the heat transfer from the inner surface of the lining to the surface is heat. Due to the complex heat transfer mechanism of conduction, the substantial heat loss of the molten metal consists of a small amount of heat absorbed in the crucible and some furnace wall loss, and the heat loss is greatly reduced compared to the conventional ladle .

If a refractory material having a large specific gravity, such as a high flumina brick, is used for the lining, the heat capacity, that is, the heat storage amount increases, and the fall of the wall surface temperature is reduced, so that the lining temperature is maintained at the initial temperature for a long time. can do.

This also means that the temperature difference between the crucible and the lining surface is small, the amount of heat transferred from the crucible to the lining is reduced, and a decrease in the temperature of the molten metal can be prevented.

As described above, in the crucible-type ladle of the present invention, the amount of heat lost by the molten metal can be reduced to, for example, about 30% of that of the conventional ladle, which can contribute to preventing the temperature of the molten metal from dropping.

In order to confirm the effects of the crucible furnace type ladle of the present invention, the present inventors manufactured a laboratory ladle using a 500 kg graphite crucible and performed the following experiments.

First, using a burner from the top and the side and lid of the experimental ladle, the temperature of the crucible was raised until a predetermined temperature was reached.
The temperature was raised at a rate of 00 ° C./10 minutes, the temperature was maintained for 15 minutes, the burner was extinguished, and hot metal at 1500 ° C. was heated for 50 minutes.
The sample was allowed to stand for 10 minutes on a hot water of 0 kg, and the change in hot metal temperature was measured.

The measurement results were as follows.

[0044] For reference, in the experiment using the conventional ladle under the same conditions as the above experiment, when the preheating temperature of the ladle was 800 ° C, the temperature drop of the molten metal was 103 ° C.

As is clear from the above table, according to the present invention, the temperature drop can be kept within 22 ° C. by preheating the graphite crucible to at least 1300 ° C.

[0046]

According to the present invention, it is possible to provide a crucible furnace type ladle which can be transported and supplied to a production line without substantially lowering the temperature of the received molten metal.

[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 a crucible furnace type ladle according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ladle 2 Casing 3 Lining 4 Molten metal 5 Suspension device 6 Crucible 7 units 8 Burner for combustion 9 Valve for combustion air 10 Valve for fuel gas 11 Combustion chamber 12 Cover 13 Metal frame 14 Lining 15 Burner 16 Valve for combustion air 17 Fuel Gas valve

Claims (2)

[Claims] 1. A ladle main body in which a graphite crucible is installed in a cylindrical container in which a refractory material is lined in a metal casing, and a metal frame large enough to cover substantially the entire upper surface of the ladle main body. It is equipped with a lid lined with refractory material, and a combustion burner equipped on the ladle main body and the lid. At the time of use, these combustion burners can heat the graphite crucible installed in the ladle from both inside and outside. Crucible furnace type ladle. 2. A crucible furnace ladle according to claim 1, wherein the graphite crucible is heated to at least 1300 ° C. by heating both inside and outside by a combustion burner.