JP2004011970A - Pig iron retainer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pig iron retainer thoroughly exhibiting characteristics of alumina, magnesia, and carbonaceous refractory, when a series of pig iron pretreatments for desulfurization and dephosphorization are performed in a same pig iron retainer, and elongating the life of the pig iron retainer. <P>SOLUTION: This pig iron retainer for performing the pig iron pretreatments of both of the desulfurization and the dephosphorization for the stored pig iron is formed by using alumina-magnesia-carbon material bricks containing carbon of 3-20 mass%, magnesia of 1-20 mass%, and alumina of 60-96 mass% for lining bricks 4, and agalmatolite bricks or chamotte bricks for permanent set bricks 5. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot metal holding container that stores hot metal that is tapped from a blast furnace or the like and that performs both desulfurization processing and dephosphorization processing of the stored hot metal.
[0002]
[Prior art]
In a blast furnace-converter pig steel integrated steelworks, hot metal discharged from the blast furnace is subjected to desulfurization, desiliconization, and dephosphorization, which are called hot metal pretreatment before being refined in the converter. It has been subjected. Initially, these hot metal pretreatments were carried out for varieties that required low phosphorus and low sulphidation in terms of steel quality, but in recent years, reduction of slag generation in converters and cost reduction by reducing Mn ore As a means of reducing not only quality requirements but also the total cost of the steelmaking process due to improvements in converter productivity, etc., almost all hot metal has been subjected to hot metal pretreatment.
[0003]
Hot metal pretreatment is carried out in a hot metal holding vessel such as a hot metal pot (also called "blast furnace pot") or a torpedo car that receives hot metal from a blast furnace and transports the hot metal to a converter. As an agent, soda ash or quick lime to which a fluorite as a flux is added is used. These refining agents have a strong erosion property against refractories, and as a result, the refractory lining of the hot metal holding vessel has been subjected to severe erosion.
[0004]
Furthermore, after the desulfurization treatment and after the dephosphorization treatment, it is necessary to discharge the refining agent added to prevent the rephosphorization and the resulfurization, and in this case, the molten metal holding container is inclined to easily discharge the refining agent. In order to perform the discharging operation in this state, the lining brick on the side wall of the hot metal holding container exposed from the hot metal repeatedly rises and falls in temperature, and is subjected to severe thermal shock.
[0005]
Such erosion and thermal shock to the lining brick become extremely severe especially when performing a series of hot metal pretreatments in the same hot metal holding vessel. This is because both the number of times of contact with the refining agent and the number of times of waste work increase.
[0006]
Therefore, various refractory materials having excellent erosion resistance and spalling resistance have been proposed and widely used as lining bricks of a hot metal holding container. As one of them, an alumina-magnesia-carbonaceous refractory has been proposed in, for example, JP-A-3-205355. In this refractory, spinel (MgO.Al ₂ O ₃ ) is formed in a matrix portion of alumina and magnesia by heat reception during use, thereby improving erosion resistance and, at the same time, improving spalling resistance by adding carbon. Refractory.
[0007]
[Problems to be solved by the invention]
However, when performing a series of hot metal pretreatments of desulfurization treatment and dephosphorization treatment in the same hot metal holding vessel, it was expected to use alumina-magnesia-carbonaceous refractory as the lining brick of the hot metal holding vessel. At present, the life extension has not been achieved as much.
[0008]
The present invention has been made in view of the above circumstances, and it is an object of the present invention to perform a series of hot metal pretreatments of desulfurization treatment and dephosphorization treatment in the same hot metal holding vessel, so that alumina-magnesia-carbonaceous refractory. An object of the present invention is to provide a hot metal holding container having a structure capable of fully exhibiting the properties of a material and achieving a prolonged life of the hot metal holding container.
[0009]
[Means for Solving the Problems]
The present inventors have intensively studied to solve the above-mentioned problems. The results of the study are described below.
[0010]
Used alumina-magnesia-carbonaceous bricks were recovered from a hot metal pot lined with alumina-magnesia-carbonaceous bricks, and the recovered bricks were examined for X-ray diffraction and microstructure. As a result, a spinel (MgO.Al ₂ O ₃ ) was formed by alumina and magnesia on the operating surface in contact with the hot metal, but no spinel was formed at a position separated from the operating surface by several mm or more.
[0011]
On the other hand, when the alumina-magnesia-carbonaceous brick and the alumina-magnesia brick placed on the ladle containing the molten steel are collected and examined for X-ray diffraction and microstructure, not only from the working surface, but also from the working surface It was confirmed that spinel was formed over a range of several tens of mm.
[0012]
Then, the reason why such a difference occurs between the hot metal ladle storing the hot metal and the ladle storing the molten steel was examined.
[0013]
In order to generate spinel by reacting alumina and magnesia in a brick, it is necessary to keep the brick at a high temperature. In the case of a ladle for storing molten steel, molten steel having a temperature of 1600 ° C. or higher, and 1650 ° C. or higher in the case of high temperature is discharged from a steelmaking furnace such as a converter into the ladle. It will be heated to the above high temperature range. And, since the molten steel is kept at a temperature in a range where the solidification phase does not precipitate, specifically, at a temperature of about 1550 ° C. or more, it can be exposed to a considerably high temperature region even at a position away from the operating surface of the lining brick. I understand.
[0014]
On the other hand, the temperature of the hot metal that is tapped from the blast furnace is much lower than that of the molten steel, and since it flows through a gutter extending over 20 m in length installed in the blast furnace cast floor, it is received by the hot metal pot, It is at most about 1400 ° C. and usually 1350 ° C. or less.
[0015]
That is, there is a difference of 200 ° C or more in the heating temperature of the ladle containing molten steel and the ladle containing hot metal due to the contents being used. Although formed, the temperature was low at a position distant from the operating surface, and it was found that spinel due to the reaction between alumina and magnesia was difficult to form. Therefore, if the lining brick of the hot metal pot is held in a high temperature range by effectively utilizing the heat of the hot metal, a spinel formation reaction occurs even in the hot metal pot holding the hot metal having a low temperature, and the life extension of the refractory is achieved. Was obtained.
[0016]
The present invention has been made based on the above-described examination results, and the hot metal holding vessel according to the first invention is a hot metal holding vessel for performing both hot metal pretreatments, that is, desulfurization processing and dephosphorization processing, on the stored hot metal. Alumina-magnesia-carbonaceous brick containing 3 to 20 mass% of carbon, 1 to 20 mass% of magnesia, and 60 to 96 mass% of alumina was used as a lining brick, and a wax brick or a chamotte brick was used as a permanent brick. It is a feature.
[0017]
A hot metal holding container according to a second invention is characterized in that, in the first invention, the alumina-magnesia-carbonaceous brick further contains 15 mass% or less of silicon carbide, and further relates to the third invention. The hot metal holding container according to the first or second aspect of the present invention is further characterized in that a heat insulating material is further provided between the lining brick and the hot metal holding container.
[0018]
In the present invention, among the refractories, particularly low-thermal-conductivity wax stone bricks or chamotte bricks are installed on the back side of the alumina-magnesia-carbonaceous brick, so that the thermal energy transmitted to the steel shell side of the hot metal holding vessel is reduced. The heat of the hot metal is suppressed, and the heat of the hot metal is efficiently accumulated in the alumina-magnesia-carbonaceous brick, and the brick can be maintained in a high temperature range. As a result, the spinel formation reaction between alumina and magnesia is promoted, and the life of the lining brick is extended.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. 1 and 2 are views showing an example of an embodiment of the present invention. FIG. 1 is a partial cross-sectional view of a hot metal pot according to the present invention as viewed from a side, and FIG. FIG.
[0020]
In the figure, a hot metal ladle 1 receives hot metal from a blast furnace as a hot metal holding vessel and transports the hot metal received to a converter. Then, desulfurization treatment and dephosphorization treatment are performed on the hot metal accommodated in the middle of the transportation to the converter. The hot metal pot 1 is covered on its outer side with a steel shell 2, and on the inner side thereof, a wax brick or a chamotte brick is provided as a permanent brick 5. The permanent brick 5 is repeatedly reused when the refractory of the hot metal ladle 1 is replaced. In the figure, two layers of the permanent brick 5 are installed. However, the number of the permanent brick 5 is not limited to two. It may be a layer or two or more layers. Moreover, although the shape differs depending on the portion where it is arranged, all of them are referred to as permanent bricks 5.
[0021]
Alumina-magnesia-carbonaceous brick is provided as an inner brick 4 on the inner surface side of the permanent brick 5 of the hot metal pot 1. The lining brick 4 directly contacts and holds the hot metal, the refining agent and the molten slag, and is also called a work brick. Above the lining brick 4, a one-stage holding brick 7 is provided, and the inner peripheral wall of the hot metal ladle 1 is formed. The holding brick 7 is pressed via the mortar 8 by the steel flange 3 provided in the circumferential direction of the upper end of the steel shell 2, and the lining brick 4 is pressed by the holding brick 7 in this manner. .
[0022]
A heat insulating material 6 made of a ceramic sheet, a castable refractory, a ceramic fiber, or the like is provided between the outside and the inside of the two-layer permanent brick 5. In the present invention, it is preferable to install the heat insulating material 6 since the heat transfer to the steel shell 2 is suppressed by the installation of the heat insulating material 6 and the temperature of the lining brick 4 can be increased. In the figure, the heat insulating material 6 is installed between the outside and the inside of the permanent brick 5 over two layers. However, even if it is installed between the steel shell 2 and the permanent brick 5, It may be installed between the permanent upholstered bricks 5 and may be installed at two or more of these places.
[0023]
The lining brick 4 is an alumina-magnesia-carbonaceous brick having a carbon content of 3 to 20 mass%, a magnesia content of 1 to 20 mass%, and an alumina content of 60 to 96 mass%.
[0024]
In the alumina-magnesia-carbonaceous brick used in the present invention, if the carbon content is less than 3 mass%, it is difficult to impart spalling resistance. On the other hand, if it exceeds 20 mass%, decarburization on the working surface of the brick is difficult. And the erosion resistance to slag decreases. Therefore, the carbon content needs to be in the range of 3 to 20 mass%, and preferably in the range of 10 to 15 mass%. As the carbon, it is preferable to use graphite such as flaky graphite and earthy graphite.
[0025]
When the magnesia content is less than 1 mass%, the amount of spinel formation is small, and improvement in erosion resistance due to spinel formation cannot be expected. On the other hand, when the magnesia content exceeds 20 mass%, the expansion amount due to spinel formation increases, and the brick structure is destroyed by this expansion. And reduce brick life. Therefore, the magnesia content needs to be in the range of 1 to 20 mass%, and preferably in the range of 5 to 8 mass%.
[0026]
Silicon carbide has an effect of improving the spalling resistance due to the low expansion of the refractory and suppressing the oxidation of carbon in the refractory. Therefore, it is preferable to mix silicon carbide in addition to the above components. The content of silicon carbide is set to 15% by mass or less, preferably 3% by mass or less. If it exceeds 15 mass%, the erosion resistance of the matrix portion is undesirably reduced. The alumina content is the balance of these.
[0027]
The hot metal from the blast furnace is received using the hot metal ladle 1 thus configured, and the hot metal accommodated in the middle of the transportation to the converter is subjected to desulfurization and dephosphorization. In this case, a desiliconization treatment may be performed before the dephosphorization treatment. The order of the desulfurization treatment and the dephosphorization treatment does not need to be particularly limited, and is appropriately determined according to the layout of each steelworks. The desulfurization treatment and the dephosphorization treatment are carried out by a usual treatment method, that is, a method using quicklime or soda ash as a refining agent.
[0028]
Since the hot metal pot 1 is configured as described above, heat from the stored hot metal is accumulated in the lining brick 4, and the alumina and magnesia in the lining brick 4 react during use of the hot metal pot 1 to line the lining. Spinel is generated in the matrix portion of the brick 4, and the erosion resistance of the lining brick 4 is improved. In addition, the lining brick 4 contains carbon for improving the spalling resistance. As a result, the lining brick 4 has a reduced amount of wear despite the frequent desulfurization and dephosphorization treatments, It can be used for a stable period.
[0029]
In the above description, the example of the hot metal ladle 1 is described as the hot metal holding container. However, the present invention can be applied to a torpedo car in accordance with the above description. Further, the present invention is not limited to the above description, and various changes can be made. For example, the holding brick 7 is not limited to one stage, and can be provided as appropriate in two to three stages or four to five stages below the top stage, depending on the dimensions of the hot metal ladle 1 and the amount of hot metal stored therein, Application of castable refractories is also possible.
[0030]
【The invention's effect】
According to the present invention, in a hot metal holding vessel for performing hot metal pretreatment of both desulfurization treatment and dephosphorization treatment, alumina-magnesia-carbonaceous bricks are used as lining bricks, and wax stone bricks or chamotte bricks are used as permanent bricks. In addition, the alumina-magnesia-carbonaceous brick as the lining brick is promoted into spinel, and the erosion resistance of the lining brick can be greatly improved. As a result, in combination with the improvement in spalling resistance due to the carbon blending, the life of the hot metal holding container can be prolonged, and industrially beneficial effects such as a significant reduction in the refractory raw material unit price can be brought about.
[Brief description of the drawings]
FIG. 1 is a view showing an example of an embodiment of the present invention, and is a partial cross-sectional view of a hot metal pot according to the present invention as viewed from a side.
FIG. 2 is a detailed view of a portion A in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Hot metal pot 2 Iron shell 3 Iron flange 4 Lining brick 5 Permanent brick 6 Insulation material 7 Holding brick 8 Mortar

Claims (3)

A hot metal holding container for performing a hot metal pretreatment of both a desulfurization treatment and a dephosphorization treatment on a contained hot metal, comprising 3-20 mass% of carbon, 1-20 mass% of magnesia, and 60-96 mass% of alumina. -Magnesia-A hot metal holding container characterized in that carbonaceous bricks are used as lining bricks and wax stone bricks or chamotte bricks are used as permanent bricks. 2. The hot metal holding container according to claim 1, wherein the alumina-magnesia-carbonaceous brick further contains 15 mass% or less of silicon carbide. The hot metal holding container according to claim 1 or 2, wherein a heat insulating material is further provided between the lining brick and the hot metal holding container iron shell.

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