KR101370369B1 - The sliding nozzle opening filler of ladle - Google Patents

Abstract

The present invention discloses a filler for sliding nozzle opening of a ladle in which a continuous casting process is used. The filler for opening the sliding nozzle of the ladle according to the present invention is a mixture of crushed chromite, olivine and silica sand, 15 to 22 wt% Fe ₂ O ₃ , 10 to 15 wt% MgO, 6 to 9 Al ₂ O ₃ Weight percent and remaining Cr ₂ O ₃ and SiO ₂ . According to this structural feature, the composition of the mixture of chromite sand and silica sand to contain the main components of the olivine to enhance the fire resistance of the filler itself, the filler composition can suppress the coagulation reaction upon contact with the molten metal as much as possible By giving a characteristic to the reaction to form a sintered layer that can effectively act in the natural opening can be obtained an effect that the natural opening of the nozzle can be made more easily.

Description

Sliding nozzle opening filler for ladle {THE SLIDING NOZZLE OPENING FILLER OF LADLE}

The present invention relates to a filler (NOZZLE) opening filler (FILLER), and more particularly to a filler composition for sliding nozzle opening of the steel ladle (LADLE) used in the continuous casting process.

Generally, in the continuous casting process of the steelmaking process, as shown in FIG. 1, a ladle 11 mounted on a trolley (not shown) or the like, which is heated in a melting furnace (not shown) such as an electric furnace, is movable. ) Is moved to the tundish 20 for the mold injection operation.

Typically, the bottom of the ladle 11 is provided with a sliding nozzle 15 driven by an actuator (not shown), such as a cylinder, to control the tapping of the molten steel, and the nozzle hole 17 of the sliding nozzle 15 is provided. In the molten steel is filled with a sand-type filler 13 to make a natural opening by the pressure of the molten steel.

As described above, the sliding nozzle opening filler has to have a certain density so that the molten steel does not penetrate into the filler when the molten steel is accommodated in the ladle, must not be floated by the specific gravity of the molten steel, and contact with the molten steel due to the high melting point. When the sintered layer is formed thin at the time, such characteristics are required. In order to have such characteristics, a mixed composition of chromite sand and silica sand is widely used, and an example thereof is disclosed in detail in Korean Laid-Open Patent Publication No. 10-2005-0023589.

On the other hand, as described above, the sliding nozzle opening filler often causes poor pore opening in which only the positive pressure of molten steel is made due to the mixing of foreign matters or the formation of an undersintered layer. For example, when such a nozzle hole defect occurs, for example, an oxygen pipe is inserted into the nozzle hole to force open the hole by oxygen injection. Therefore, the hole opening work takes a long time, resulting in a decrease in productivity and quality of the continuous casting process and a high risk of safety accident. .

Indirect factors affecting the poor pore opening of the nozzle for filler opening as described above may be caused by various forms such as the tapping temperature and tapping speed of the converter, the preheating time and temperature of the ladle before and after filling, and the filling amount of the filler. do.

Therefore, in the field where the continuous casting process is actually performed, the cause of filler hole defect is so diverse and complicated that it is not easy to identify, and efforts are being made to minimize the hole defect by improving the quality and characteristics of the filler itself. to be. As part of such efforts, it is necessary to develop a composition for satisfying requirements such as the low reactivity with molten steel, the penetration of molten steel is small, the sintered layer is easily destroyed by molten steel static pressure, and is not washed out by molten steel. .

Therefore, the present invention was created in view of the problems with the sliding nozzle filler of the conventional ladle as described above, and an object of the present invention is to induce an optimum sintering state effective for natural opening during contact reaction with molten steel An object of the present invention is to provide a filler for a sliding nozzle opening of a ladle having an improved composition to further increase the natural porosity.

In order to achieve the above object, the sliding nozzle filler of the continuous casting ladle according to the present invention is a mixture of chromite, olivine and silica of pulverized particles, 15 to 22% by weight of Fe ₂ O ₃ , 10 to 15% by weight of MgO, Al ₂ O ₃ It is characterized by including 6 to 9% by weight and the remaining Cr ₂ O ₃ and SiO ₂ .

According to one aspect of the invention, the olivine is preferably contained at least 50% by weight of forsterite (Mg ₂ SiO ₄ ). And, the olivine is preferably made of a sand having a particle size specification in the range of 0.1 to 1.0mm and a spherical grain.

According to another aspect of the invention, the mixed composition of chromite and olivine and silica sand may further comprise a binder within 1.0% by weight of the total weight. In addition, the mixed composition of chromite, olivine, and silica sand may further include 0.1 to 0.5% by weight of a coating agent.

According to the filler for opening the sliding nozzle of the ladle according to the present invention, by mixing the composition of chromite and silica sand so as to contain the main components of the olivine to enhance the fire resistance of the filler itself, the filler composition solidifies upon contact with the molten metal Since the sintered layer is formed in the state of suppressing the reaction as much as possible, the filler may be easily crushed only by the static pressure of the molten metal when the molten metal is accommodated in the ladle, thereby obtaining the effect of making the natural opening of the nozzle easier.

Therefore, as the natural porosity of the sliding nozzle of the ladle can be improved, the productivity and quality of the steelmaking process and the continuous casting process can be improved, and the safety of the operator can be obtained.

1 is a schematic cross-sectional view shown for explaining the sliding nozzle of the ladle used in the continuous casting process,
2 to 4 are photographs showing the results of the sintering test of Comparative Examples 1 to 3 of the present invention.
5 to 7 are photographs showing the sintering test results of the sliding nozzle opening filler according to Examples 1 to 3 of the present invention by photographs.

Hereinafter, the filler for sliding nozzle opening according to the present invention will be described in detail through comparison of the comparative example and the embodiment.

The filler for opening the sliding nozzle of the ladle according to the present invention is a mixture of chromite, olivine and silica sand in pulverized particles, 15 to 22 wt% Fe ₂ O ₃ , 10 to 15 wt% MgO, Al ₂ O ₃ 6-9 wt% and the remaining Cr ₂ O ₃ and SiO ₂ .

According to the filler for sliding nozzle opening according to the present invention having the composition ratio as described above, the fire resistance of the filler itself is improved by mixing and mixing so that the main components of olivine are contained in the conventional composition composition of chromite and silica sand By providing the filler composition, the filler composition is provided with the property of suppressing the coagulation reaction upon contact with the molten metal.

Therefore, according to the sliding nozzle opening filler according to the present invention having the composition ratio as described above, the sliding nozzle is reacted to form a sintered layer that can effectively act in the natural opening when contacted with the molten metal received in the ladle, the sliding nozzle The natural opening of the will be made easier to work.

In the sliding nozzle opening filler according to the present invention, chromite is additionally added to the mixed composition of chromite and silica sand by adding 5 or 10% by weight of olivine sand containing 50% by weight or more of forsterite (Mg ₂ SiO ₄ ). And the samples prepared by mixing so as to adjust the content within the range of 50 to 70% by weight and 10 to 30% by weight, respectively, and divided into Comparative Examples 1 to 3 and Examples 1 to 3, respectively, After the sintering test was performed by analyzing the component composition ratios, the composition ratios obtained by measuring the thicknesses of the sintered layers for the respective samples to obtain an effective result are limited to the composition ratios of the fillers as described above.

Table 1 shows the components of each of the fillers prepared in different mixing ratios by adding chromite sand, silica sand and olivine sand to each of Comparative Examples 1 to 3 and Examples 1 to 3, respectively. It is shown by analyzing the composition ratio.

 Sand Mixing Ratio and Component Composition Ratio for Filler Formation of Comparative Examples and Examples  Sand classification   Comparative Example 1   Comparative Example 2   Comparative Example 3   Example 1   Example 2   Example 3 Chromite    70wt%   50 wt%    50 wt%   50 wt%    60wt%    70wt% Silica sand    30wt%   40wt%    10wt%   20wt%    20wt%    10wt% peridot      -   10wt%    40wt%   30wt%    20wt%    20wt%    ingredient    Composition ratio   Composition ratio   Composition ratio   Composition ratio   Composition ratio   Composition ratio Fe ₂ O ₃   18.0wt%   15.0 wt%    21.0wt%   19.0wt%   20.0wt%   22.0 wt%  MgO    4.0wt%    6.0wt%    16.0wt%   13.0wt%   10.0wt%   11.0wt% Al ₂ O ₃    9.0wt%    7.0wt%     7.0wt%    7.0wt%    8.0wt%    9.0wt% Cr ₂ O ₃   30.0wt%   21.0wt%    21.0wt%   21.0wt%   26.0wt%   30.0wt%  SiO2   39.0wt%   51.0wt%    35.0 wt%   40.0wt%   36.0 wt%   28.0wt%

Here, each sample contains 0.2 wt% or less of R ₂ O, which is an unavoidable impurity.

Table 2 shows the results of measuring the thickness of each of the sintered layer by performing the sintering test of the samples of Comparative Examples 1 to 3 and Examples 1 to 3 under the following test conditions.

Sintering test conditions for obtaining the results of the following Table 2 are compared to the graphite crucibles (101 to 106) having the specifications of the upper outer diameter 80mm, lower outer diameter 60mm, thickness 10mm, height 100mm as shown in Figure 2-7 After filling the samples 111 to 116 of Examples 1 to 3 and Examples 1 to 3, and then naturally cooling by heating at 1,650 ° C. for 1 hour by an electric furnace, the surface softening layer, the reaction sintering layer and the thickness thereof were combined. The result of the measurement is shown as a number.

Sintering test result of the filler sample by a comparative example and an Example    division  Comparative Example 1  Comparative Example 2  Comparative Example 3  Example 1  Example 2  Example 3 Surface Softening Layer (mm)     15     16     13      13       12      10 Reaction sintering layer (mm)      7      6      7       5        6       7 Total sintered layer (mm)     29     23     20      18       17      15

Referring to Table 2, the samples of Comparative Example 1, Comparative Example 2 and Comparative Example 3 are 20 mm, 23 mm, and 29 mm thick, respectively, as shown in FIGS. The measurement result formed was obtained.

In addition, the samples of Example 1, Example 2, and Example 3, as shown in the photographs in Figs. 4, 6 and 7, respectively, can obtain the measurement results in which the sintered layer was formed with a thickness of 18 mm, 17 mm, and 15 mm, respectively. .

Thus, as a mixture of crushed chromite, olivine and silica sand, 15 to 22 wt% Fe ₂ O ₃ , 10 to 15 wt% MgO, Al ₂ O ₃ Sliding nozzle for opening the sliding nozzle of the ladle according to the present invention having a composition ratio including 6 to 9% by weight and the remaining Cr ₂ O ₃ and SiO ₂ , as the solidification reaction is suppressed as much as possible in contact with the molten metal by enhancing the degree of fire resistance Since the sintered layer has a thinner characteristic, it is possible to obtain an effect that the natural opening of the sliding nozzle of the ladle can be made more easily.

Hereinafter, the reaction action and the function of each component of the sliding nozzle opening filler according to the present invention will be described.

OLIVINE is represented by the formula (MgFe) ₂ SiO ₄ because Mg ₂ SiO ₄ named FORSTERITE and Fe ₂ SiO ₄ named FAYALITE are calculated in solid solution form. Theoretical composition ratio is composed of 32wt% MgO, 47.6wt% SiO _{2, and} 20.4wt% Fe ₂ O ₃ (+ FeO).

The paylight (Fe ₂ SiO ₄ ) and the posterlite (Mg ₂ SiO ₄ ) has a melting temperature of 1205 ° C. and 1905 ° C., respectively, and the posterlite (Mg ₂ SiO ₄ ) is melted at a relatively high temperature.

Therefore, according to the present invention, it is necessary to select olivine having a high content of posterlite (Mg ₂ SiO ₄ ) for the purpose of obtaining the effect of enhancing the fire resistance of the filler itself using the MgO component contained in the olivine. It is preferable that 50 wt% or more of forsterite (Mg ₂ SiO ₄ ) is contained.

In addition, the olivine sand for forming the sliding nozzle opening filler according to the present invention requires an appropriate particle size standard and a limitation on the size of the particles, and a spherical sand having a particle size in the range of 0.1 to 1.0 mm is preferable. The following describes the particle size standard of the olivine sand and the reason for limiting the shape of the olive sand.

If the particle size of the olivine sand is formed to be 0.1 mm or less, the density of the sintered layer may be too thick due to the fine particles, and thus the natural opening becomes difficult. In the case where the particle size standard is formed to be 1.0 mm or more, the effect of forming a thinner sintered layer can be obtained, while the density of the sintered layer is lowered, so that the molten steel is easily penetrated, so that natural opening is difficult. do.

Silica sand it is preferred to use the natural history greater than the content of SiO ₂ 99%, because the porous defects by the case the content of the purity of SiO ₂ lower most R ₂ O in the form of impurities present to promote the over-production of low-melting-point material Because it can provide the cause.

And, the particle size of the silica sand is preferably limited to the range of 0.1 ~ 2.0mm, the reason for this limitation is substantially the same as the reason for limiting the particle size of the olivine sand.

Chromite sand is intended to prevent penetration or erosion of molten steel due to its high degree of fire resistance, and preferably has a particle size specification of 1.0 mm or less.

According to one aspect of the present invention, as a binder for securing the binding property of the filler sand, for example, a thermosetting resin such as phenol resin or a known organic binder may be added together with the alcohol, and as a coating agent for curing, graphite and carbon Can also be added.

The coating of carbon and graphite is intended to provide lubricity during natural opening, to reduce thermal conductivity of the carbon material, and to suppress the expansion rate caused by the MgO component of the olivine, in addition to inhibiting oxidation of each melt.

It is preferable to add the binder (binder) and the coating agent so as to satisfy the range of 1.0 wt% and 0.1 to 0.5 wt% of the total weight of the filler composition, respectively, so as not to cause deterioration of corrosion resistance or density.

In the present invention, the reason for using the olivine is because the content of the olivine component (particularly MgO) can provide an effect of enhancing the degree of fire resistance and forming an effective sintered layer upon reaction with the molten metal. In other words, when reacted with Fe ₂ O ₃ and MgO, one of the constituents of the olivine, a high viscosity liquid film is formed, and the liquid film prevents the penetration of the melt. Accordingly, the liquid film fills the pores of the filler or forms a film on the surface to inhibit the high temperature oxidative property of the graphite and at the same time block the heat transfer to the lower side to enable the formation of an effective sintered layer.

On the other hand, another reason for using olivine is because it can utilize the component of Al ₂ O _{3 which} is the main component of the fireproof wall or inclusions in the steel.

The reaction of Al ₂ O ₃ + MgO generates a melt at 1200-1300 ° C., and the melt has a volume expansion and thus causes a slight incontinence at each interface. When this phenomenon occurs at the interface where the molten metal and the filler abut, the filler is easily broken by iron positive pressure due to the incontinence, thereby making natural openings easier.

Al ₂ O ₃ + MgO + SIO ₂ secondary to form a liquid compound at 1300 ℃, when the liquid compound reacts with MgO other than Si when reacted with Fe ₂ O ₃ to form a high viscosity liquid film melt This can prevent the penetration. Accordingly, the liquid film fills the pores of the filler or forms a film on the surface to inhibit the high temperature oxidative property of the graphite and at the same time block the heat transfer to the lower side to enable the formation of an effective sintered layer. In addition, it is possible to prevent the phenomenon that the filler sand clings to the fireproof wall to block openings by forming incontinence on the fireproof wall inside the nozzle.

Hereinafter, the action of the sliding nozzle opening filler according to the present invention having the composition as described above will be described in detail.

When the molten metal is accommodated in the ladle filled with the filler in the sliding nozzle, the R ₂ O components present in the olivine and silica sand are melted first and remain at the interface between the filler and the molten metal. Since the low melting point material has a low viscosity, the low melting point material is suspended due to the vortex shape of the molten metal. Secondly, FeO and SiO ₂ react to form a low melting point material called payarite.

Subsequently, low melting point materials of Al ₂ O ₃ + MgO, Al ₂ O ₃ + MgO + SIO ₂ , and Fe ₂ O ₃ + MgO are simultaneously generated to form a film at the top of the filler (abutment with the molten metal). At this time, the low-viscosity materials with low viscosity float off due to the strong vortex formation of the molten metal, while the high viscosity Fe ₂ O ₃ Since the low-melting point material of + MgO is attached to the filler as it is to block the pores of the silica sand or chromite sand, it is possible to reduce the heat transfer downward by preventing the oxidation of the graphite of the filler lower layer at high temperature.

In addition, the solidified material formed by the reaction of high-purity silica sand or chromite sand, in which high-viscosity liquids or other low-melting materials have not yet melted, is formed on the surface of the filler under the influence of MgO (slightly expandable). (This is not an incontinence due to the spalling phenomenon, so the penetration of molten steel is practically difficult).

Therefore, due to the above incontinence, the filler may be easily broken while being subjected to iron positive pressure when the sliding nozzle is opened. Particularly, the lower part of the sintered layer of the filler, which is relatively less affected by high temperature, is slippery because the high temperature oxidation of graphite is suppressed. Since it can be easily exited by satisfying, the natural opening of the filler can be easily made.

11: ladle 12: molten steel
13: filler 15: sliding nozzle
17: nozzle port 122: stirring blade
130: transfer unit 131: connector
140: sensor unit 141: lifting member
142: magnetic material 143: magnetic sensor

Claims (5)

A mixture of olivine and silica sand containing chromite in the form of crushed particles and at least 50% by weight of forsterite (Mg ₂ SiO ₄ ), 15 to 22% by weight of Fe ₂ O ₃ , 10 to 15% by weight of MgO, Al ₂ O ₃ 6-9% by weight and the remaining Cr ₂ O ₃ and SiO ₂ , the mixed composition of chromite, olivine and silica sand further comprises 0.1 to 0.5% by weight of the total weight of the coating agent and a binder within 1.0% by weight of the total weight Include,
The olivine is a filler for opening the sliding nozzle of the ladle, characterized in that made of sand having a particle size of the range of 0.1 to 1.0mm and a spherical shape. delete delete delete delete

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