JP4667110B2 - Filling material for ladle sliding opening and closing device - Google Patents

Description

  The present invention relates to a filler for a ladle sliding opening / closing device. More specifically, the present invention relates to a ladle that can be easily dropped and opened in a steelmaking factory without being easily melted by high-temperature molten metal received by a ladle and without being penetrated by sintered and molten metal. The present invention relates to a filler for a dynamic opening / closing device.

  A ladle used in a steelmaking factory is provided with a sliding opening / closing device (sliding nozzle or rotary nozzle) at the bottom in order to control the discharge and flow rate of molten steel. In order to prevent the molten steel from solidifying in the nozzle, such a sliding opening and closing device is generally filled in the nozzle with packed sand having a high fire resistance (hereinafter referred to as filler) in advance. The ladle that is opened opens the sliding device, so that the filler first falls and then the molten steel flows out naturally (hereinafter referred to as natural opening). At this time, if the filler solidifies due to sintering, high-temperature melt penetration, etc., preventing the natural outflow of molten steel (hereinafter referred to as poor hole opening), the worker reheats and melts the solidified part with an oxygen pipe or the like. It is necessary to discharge the molten steel, and a great deal of damage occurs due to the danger of occupational accidents and deterioration of quality due to oxidation of the molten steel. Therefore, it was indispensable to develop a filler that brings the natural hole ratio (= the number of natural holes / the total number of times used × 100 (%)) close to 100%.

  As such fillers, those using natural silica sand, olivine sand, zircon sand, granular alumina and the like have been studied. However, since the balance between performance and cost is poor, a combination of chromite sand and silica sand, which are relatively inexpensive and have high fire resistance, is now mainstream.

  A filler combining chromite sand and silica sand is excellent in that a high natural porosity can be obtained relatively easily. However, the use of chromite sand is not desirable from the viewpoints of safety and environmental problems because of the risk of reacting and producing harmful hexavalent chromium.

  Against this background, in order to obtain a safer and lower cost filler, development of a filler that does not use or reduces chromite sand is required.

As a conventional filler using silica sand, Japanese Patent Application Laid-Open No. 62-244570 (Patent Document 1) discloses that the SiO ₂ content is 96% by weight and the Al ₂ O ₃ content is 2.0% by weight or less. A mixture of silica sands having a particle size distribution of 0.71 to 1.68 mm, 60 to 75% by weight, 0.10 to 0.71 mm of sand being 25 to 40% by weight, and less than 0.1 mm A filler in which sand is 5% by mass or less is disclosed.

JP-A-1-180776 (Patent Document 2) discloses a filler having a particle size distribution of 2.38 to 0.125 mm and a porosity of 25 to 50%.
However, even in these fillers, the natural porosity was about 97 to 98%, which was not satisfactory.

On the other hand, in Japanese Patent No. 2732795 (Patent Document 3), silica sand having a particle size distribution of 0.3 to 1.7 mm and a particle shape factor of 1.4 or less, and an Al ₂ O ₃ content of 2 is used. A filler is disclosed in which the content of K ₂ O and Na ₂ O is 1% by weight or less. In this patent, in order to improve the fire resistance compared with the filler disclosed in Japanese Patent Application Laid-Open Nos. 62-244570 and 1-180776, 0.3 mm which causes oversintering (Example) Therefore, by removing Al ₂ O ₃ , K ₂ O and Na ₂ O components (impurities) that increase the meltability of silica sand, it is possible to achieve higher fire resistance. It is described that a filler of the same degree is obtained. In addition, this patent states that the use of rounded silica sand can prevent melt penetration.

JP-A-62-244570 JP-A-1-180776 Japanese Patent No. 2732795

  If the filler of the said patent was used, the natural open area ratio of 99.26% or more was obtained if it was the steelmaking conditions at the time of the application of this patent. However, it may not be sufficient under recent steelmaking conditions at a higher temperature and for a longer time, and it is desired to provide a filler that can further improve the natural porosity.

  The inventors of the present invention surprisingly realize that a natural open area ratio can be obtained even under the above-mentioned recent steelmaking conditions by using a filler for a ladle sliding opening / closing device containing a specific proportion of silica sand having a different alkali content. The present invention was found out.

Thus, according to the present invention, 80 to 50% by mass of the first silica sand having an alkali content of 0.8 to 1.4% by mass and 20 % to 2nd silica sand having an alkali content of 0 to 0.05% by mass. 50 wt% Tona is,
The first silica sand contains 90% by mass or more of silica sand having a particle size distribution of 0.6 to 1.7 mm and 50% by mass or more of silica sand having a particle size distribution of 0.85 to 1.7 mm, The ladle comprises 90% by mass or more of silica sand having a particle size distribution of 0.212 to 0.85 mm and 50% by mass or more of silica sand having a particle size distribution of 0.212 to 0.6 mm. A filler for a sliding opening and closing device is provided.

  According to the present invention, a ladle sliding opening and closing that can be easily dropped and opened in a steelmaking factory without being melted easily even by high-temperature molten metal received in a ladle, and without penetration of sintered and molten metal. Device fillers can be provided. Furthermore, with known fillers, a satisfactory hole ratio can be obtained even under heavy refining conditions (a molten steel holding time of 100 minutes or more and a steel receiving temperature of 1660 ° C. or more) where it is difficult to obtain a satisfactory hole ratio. Can do.

In the present invention, the ladle sliding opening / closing device filler (hereinafter also simply referred to as filler) contains 80-50% by mass of first silica sand containing 0.5% by mass or more of alkali and alkali content. It has been found that the sinterability of the filler can be reduced by comprising 20 to 50% by mass of the second silica sand of less than 0.5% by mass. In the present invention, silica sand containing an alkali component similar to that of generally collected silica sand as shown in the first silica sand exhibits high sinterability, whereas it is prescribed in the second silica sand. As described above, the fact that the sinterability of silica sand containing almost no alkali is low is utilized. Here, the alkali content means the total of K ₂ O and Na ₂ O components measured according to the fluorescent X-ray analysis method specified in JIS-R2216.

When at least 20% by mass or more of the second silica sand is blended with the first silica sand, an effect of apparently reducing the sinterability is obtained. In addition, this effect becomes so high that the mixture ratio of 2nd silica sand is increased to 50 mass%. When the amount exceeds 50% by mass, the second silica sand has a low alkali content. In other words, the SiO ₂ purity is high, so the coefficient of thermal expansion is high. As a result of the thermal expansion of the second silica sand, the filler is slid. It is not preferable because a shelf-hanging phenomenon occurs in the dynamic opening / closing device (particularly the nozzle) and the natural hole area ratio deteriorates.

  More preferably, the blending ratio of the first silica sand and the second silica sand is 80 to 60% by mass and 20 to 40% by mass, and the more preferable blending ratio is 75 to 65% by mass and 25 to 35% by mass. is there.

  Moreover, in this invention, the alkali content of 1st silica sand is 0.5 mass% or more, and the alkali content of 2nd silica sand is less than 0.5 mass%. When two types of silica sands having different alkali contents are used as described above, the melt can be held by the silica sand having a high alkali content, and the penetration prevention property of the melt can be improved by the silica sand having a low alkali content.

  When the alkali content of the first silica sand is less than 0.5% by mass, the penetration prevention property of the melt is not sufficient, which is not preferable. When the alkali content of the second silica sand is 0.5% by mass or more, the sinterability becomes too strong, which is not preferable. More preferable alkali contents of the first silica sand and the second silica sand are 0.5 to 3.0 mass% and 0 to 0.1 mass%, respectively, and particularly preferable alkali contents are 0.8 to They are 1.4 mass% and 0-0.05 mass%.

  Furthermore, in the present invention, the preferred filler is a silica sand having a particle size distribution of 0.6 to 1.7 mm and a silica sand having a particle size distribution of 0.85 to 1.7 mm. 50% by mass or more, and the second silica sand is 90% by mass or more of silica sand having a particle size distribution of 0.212 to 0.85 mm and 50% by mass of silica sand having a particle size distribution of 0.212 to 0.6 mm. It is a filler containing the above. Here, the particle size distribution means a value measured according to a particle size test method defined in JIS-Z2602.

  The filler mixed with silica sand having the above particle size distribution is usually in the range of 0.85 to 1.7 mm and 0.212 to 0.6 mm in the particle size distribution after mixing, for example, as shown in FIG. It is preferable that two peaks exist or have an inflection point A within two ranges as shown in FIG. In the filler of the present invention, it is particularly preferable that the alkali content of silica sand in the range of 0.212 to 0.6 mm is less than 0.5% by mass.

  In the patent described in the background art, the fire resistance of the filler is improved by removing particles of less than 0.3 mm (substantially less than 0.6 mm from the examples). However, when such particles are removed, the melt penetration resistance is reduced, and it is difficult to obtain a sufficient natural porosity. In contrast, the present invention improves the fire resistance of the filler (sintering) by using the second silica sand having a low alkali content and low sinterability without removing the fine particles that have been removed. It has been found that both the reduction of the property and the penetration prevention property of the melt can be achieved, and as a result, the natural porosity can be improved.

  When the first silica sand containing 90% by mass or more of sand having a particle size distribution of 0.6 to 1.7 mm and 50% by mass or more of sand having a particle size of 0.85 to 1.7 mm is used, this has an alkali content of at least 0.5. Even if it is silica sand with high sinterability containing at least mass%, the sinterability can be kept relatively low. Actually, the first silica sand has a molten steel temperature received by the ladle (hereinafter referred to as the “received steel temperature”) of less than 1,660 ° C., and the molten steel holding time in the ladle (from the received steel to the continuous casting machine). The inventors have found that if the time taken to open the ladle sliding device is less than 100 minutes, a natural hole area ratio close to 100% can be obtained. The alkali content of the first silica sand is desirably about 0.5 to 3.0% by mass in order to keep the coefficient of thermal expansion low.

  Such alkali-containing first silica sand can also be obtained by blending silica sand with feldspar containing 80% by mass or more of a particle size distribution of 0.6 mm to 1.7 mm. In addition, the alkali content contained in feldspar is normally 7-14 mass%. Furthermore, it is preferable that the mixture ratio with respect to the 1st silica sand of a feldspar is 30 mass% or less. Since feldspar particles are generally angular in shape, mixing at 30% by mass or more is not preferable because the filling property may be deteriorated. A more preferable blending ratio of feldspar is 20% by mass or less.

  The feldspar added is preferably potassium feldspar. These potash feldspars include butterfly stones, bishacarite stones, spinach stones, kooricho stones, etc., but are not limited to these, and these can be used alone or in combination of two or more. is there.

  The second silica sand preferably contains 90% by mass or more of sand having a particle size distribution of 0.212 to 0.85 mm and 50% by mass or more of sand of 0.212 to 0.6 mm. This is because it is effective to mix fine particles of 0.212 to 0.85 mm, more specifically 0.212 to 0.6 mm, in order to prevent penetration of a high-temperature melt such as gold. In particular, in the case of steelmaking in which the steel receiving temperature is 1,660 ° C. or higher and the molten steel holding time in the ladle is 100 minutes or longer, the occurrence of poor opening due to penetration of the high-temperature melt becomes more prominent. Therefore, if the second silica sand is blended, occurrence of poor opening can be suppressed. Furthermore, because the alkali content of the second silica sand is less than 0.5% by mass, the sinterability can be kept extremely low even for fine particles that are easily sintered.

  The second silica sand having the above specific particle size distribution and alkali content is contained at least 20% by mass or more with respect to the total of the first and second silica sands, so that the sinterability of the filler is reduced. The permeability of the high-temperature melt can be reduced while keeping it. As a result, it becomes possible to bring the natural hole area rate close to 100%.

  The first and second silica sands preferably have a particle shape factor of less than 1.4. By having this particle shape factor, the filling property is improved and the penetration of the high temperature melt can be more effectively reduced. A more preferred particle shape factor is less than 1.3. Here, the particle shape factor means a value calculated using a sand surface area measuring device (manufactured by George Fischer). Specifically, the particle shape factor indicates a value obtained by dividing the surface area of actual sand particles (silica sand) per gram by the theoretical surface area obtained by assuming that the sand particles are true spheres. Therefore, the closer the grain shape factor is to 1, the closer the sand grain is to a true sphere.

  In general, silica sand has an alkali content of 0 to 7% by mass depending on the place of production. In particular, the alkali content of silica sand produced in Japan is distributed in the range of 0.1 to 7% by mass, and the alkali content of silica sand produced overseas is distributed in the range of 0 to 7% by mass. Therefore, what is necessary is just to select sand from each production place in order to obtain the filler of a desired property.

In addition, in order to make the quality of said silica sand and feldspar constant, you may use the sand which gave the grinding process. Furthermore, two or more sands that have been subjected to grinding treatment and sand that has not been subjected to grinding treatment may be mixed and used.
The grinding process includes a known dry process and wet process. Further, a dry method and a wet method may be combined.

  In the dry method, the raw sand is lifted in the device by a high-speed air current and collides with the collision plate. A high-speed rotating scrubber device that feeds raw sand and polishes it by collision and friction between the projecting sand generated by its centrifugal force and the falling thrown-in sand, and an agitator that uses the friction between sand grains to polish Examples thereof include a method using a high-speed stirrer such as a mill.

  On the other hand, the wet method includes a method using a trough-type grinding machine that performs a grinding process by friction between sand grains in a trough with rotating wings.

  Of these grinding processes, it is desirable to use a wet method. This is because sand smaller than the desired particle size can be simultaneously removed by washing with water during the grinding process. However, even with the dry method, sand having the same degree as that of the wet method can be obtained by providing a water washing apparatus.

  In addition, the first silica sand, the second silica sand, or the first silica sand and the second silica sand are added in an amount of 0.05 to 1.0% by mass of carbon (for example, scaly graphite, soil-like). The entire surface or a part of the surface is preferably coated with graphite, carbon black or the like. By using coated silica sand, it is possible to effectively reduce high temperature melt penetration and sintering. If the amount of carbon added exceeds 1.0% by mass, it becomes difficult to form a sintered layer due to the action of carbon, which causes the generation of non-open pores. Since charcoal is promoted, a problem may occur on the composition of the molten steel, which is not preferable.

  The method of coating the surface of the silica sand with carbon is not particularly limited. For example, the silica sand is charged separately or simultaneously with a ribbon-type blender in separate or the same apparatus and then charged with carbon. There is also a method of electrostatic coating by further stirring. In this case, the potential of static electricity generated in the filler by stirring has an amount of static electricity corresponding to a potential of −0.1 kv or more, but is preferably in the range of −0.1 to −0.05 kv. . By having a potential of −0.1 kv or more, a filler substantially free of free carbon can be obtained. Further, by this stirring, carbon can be electrostatically coated on the entire surface or a part of the silica sand.

  In the present invention, carbon black is preferable among the carbons. The carbon black that can be used is not particularly limited and may be a known one, but it is preferable to use granular carbon black from the viewpoint of hygiene and the performance and cost of the filler. As the granular product, for example, it is more preferable to use a product obtained by granulation by a dry method or a wet method. The particle size distribution of the granular product is preferably 2000 μm or less, and more preferably 250 to 2000 μm.

  Furthermore, chromite sand, zircon sand, alumina sand, carbon and the like may be included as long as the effects of the present invention are not impaired. The proportion of the first and second silica sands in the filler is preferably 50% by mass or more, and more preferably 70% by mass or more. Further, in order to finely adjust the particle size distribution and alkali content of the filler, silica sand having a predetermined particle size distribution and alkali content may be further added.

  The filler of the present invention can be filled in the nozzle in the ladle sliding opening / closing device in the same manner as a known filler. Moreover, you may use a filler so that a nozzle may be filled and it may rise on a nozzle and its peripheral region. Further, the filler used for the nozzle is a known mixed sand of silica sand and chromite sand, and the filler used so as to rise on the nozzle and its peripheral region is used as the filler of the present invention. Can be improved. It is preferably a mixed sand having a particle size distribution of 0.85 mm or less. More preferably, it is a mixed sand containing 90% by mass or more of sand having a particle size distribution of 0.85 to 0.15 mm and having an alkali content of 0.5% by mass or less.

Furthermore, the use ratio of the mixed sand and the filler of the present invention is preferably 0.5 to 1: 1 (mass ratio).
The silica sand and chromite sand constituting the mixed sand preferably have a particle shape factor of less than 1.4. By having this particle shape factor, the filling property is improved and the penetration of the high temperature melt can be more effectively reduced. A more preferred particle shape factor is less than 1.3.

Although an experiment example and an Example are shown below, this invention is not limited to this.
Experimental example 1
When the alkali content of silica sand was limited to less than 0.5% by mass, a test for confirming a phenomenon in which the sinterability decreased specifically was performed.

Specifically, it contains 90% by mass or more of sand having a particle size distribution of 0.212 to 0.85 mm, 50% by mass or more of sand of 0.212 to 0.6 mm, and an alkali content of 0 to 2.5% by mass. Prepared silica sand (corresponding to the second silica sand) prepared in step 3, molded to 30 mmφ × 30 mm height using an organic binder, dried, and then embedded and restrained in a refractory crucible with low sintering aggregates . A test piece obtained by heating and sintering this refractory crucible together with an electric furnace in an atmosphere of 1,600 ° C. for 2 hours at room temperature is a hydraulic universal tester (trade name: MR-30-, manufactured by Maekawa Test Instruments Co., Ltd.). ACT) to determine the residual compressive strength.
The results are shown in Table 1.

  From Table 1, no sintering was observed when the alkali content was 0% by mass, and very slight sintering was observed even when the alkali content was 0.5% by mass. However, considerable sintering was observed when the alkali content was 1.0% by mass, and a strong sintered body was obtained at 2.5% by mass. Therefore, it was confirmed that the sinterability can be specifically reduced by limiting the alkali content of silica sand to 0.5% by mass or less.

Experimental example 2
The mass ratio of the second silica sand contained in the filler and the liquid (water) permeability with respect to the filler blended by changing the ratio of the first silica sand and the second silica sand shown in Table 2. Table 3 shows the results of investigating the relationship between the ratio and the second silica sand blending ratio and the sintered compact residual compressive strength obtained by firing the filler at 1,600 ° C. The liquid penetration amount was used as an alternative value for the permeability of the high-temperature melt in a liquid state, and the sintered compact residual compressive strength was used as an alternative value for the sinterability of the filler. Further, in the experimental example, the second silica sand (A) substantially free of alkali content was used in the second silica sand, and in the comparative experimental example, the alkali content was 2.5 mass% as the second silica sand. The contained second silica sand (B) was used.

Thereafter, the same second silica sand was properly used in all of the experimental examples and the comparative experimental examples.
The liquid permeation amount represents the amount of a 50 mmφ water column that passes through the inside of the filler filled in a cylindrical container having a height of 50 mmφ × 51 mm. Specifically, it was calculated from the permeability coefficient of silica sand measured by a constant water level method using a soil permeability measuring device (trade name: DIK-4000, manufactured by Daikiri Chemical Co., Ltd.).

  As a result, it was confirmed that when the ratio of the second silica sand contained in the filler reached 20% by mass regardless of the experimental example and the comparative experimental example, the liquid penetration amount into the filler was greatly reduced. Therefore, it was analogized that the permeability of high-temperature melts such as slag and molten steel is reduced by setting the ratio of the second silica sand to 20% by mass or more. The amount of particles of 0.212 to 0.6 mm contained in the filler at this time was almost 14% by mass. It was also confirmed that this effect was higher in the second silica sand of the experimental example having a smaller particle shape factor.

  On the other hand, in the sintered compact residual compressive strength of each filler, a remarkable difference was recognized between the experimental example and the comparative experimental example. In the case of the experimental example, the residual compression strength of the sintered body decreases due to the increase in the blending ratio of the second silica sand, whereas in the case of the comparative experiment example, the residual compression of the sintered body due to the increase in the blending ratio of the second silica sand. It was confirmed that the strength increased greatly. Therefore, it became clear that the sinterability of the filler can be kept low by blending the second silica sand substantially free of alkali.

  From the above results, the first silica sand substantially free of particles less than 0.6 mm as shown in Table 2 is substantially free of alkali as shown in the examples. It was found that by adding at least 20% by mass of the silica sand, a filler having reduced sinterability while reducing permeability of high-temperature melts such as slag and molten steel was obtained.

Examples 1-3 and Comparative Examples 1-3
Using the silica sand raw material shown in Table 2, various fillers shown in Table 4 were produced, and these fillers were slid as shown in FIG. 2 provided at the bottom of a 250-t ladle at a steelmaking factory. Table 6 shows the natural porosity obtained by filling the dynamic opening / closing device and using it about 200 times. In FIG. 2, 1 is a filler, 2 is a receiving brick, 3 is an upper nozzle, 4 is a stationary platen, 5 is a sliding platen, and 6 is a lower nozzle. In Examples 1 to 3 and Comparative Example 2, the second silica sand (A) in Table 1 was used as the second silica sand, and in Comparative Example 3, the second silica sand (B) was used.

  Use conditions are classified by molten steel holding time and receiving steel temperature. Light refining conditions with relatively easy thermal conditions (melting steel holding time less than 100 minutes and receiving steel temperature less than 1660 ° C) and severer smelting conditions with more severe heat conditions The natural open area ratios were individually determined and compared for the molten steel holding time of 100 minutes or more and the steel receiving temperature of 1660 ° C. or more. The specific molten steel holding time and steel receiving temperature were 45 to 99 minutes and 1550 to 1659 ° C. under light refining conditions, and 100 to 300 minutes and 1660 to 1720 ° C. under heavy refining conditions.

  Further, as Example 3, as shown in FIG. 3, the lower layer in the nozzle is filled with a filler (grain shape factor 1.27) in which 30% by mass of silica sand and 70% by mass of chromite sand are mixed, and the upper layer is filled. 30 kg of the silica sand of Example 2 was heaped up and the natural porosity was measured. Table 5 shows the particle size distribution and alkali content of the filler used in the lower layer. In FIG. 3, 1a means a filler upper layer part, and 1b means a filler lower layer part (2-6 are the same as FIG. 2).

  In addition, as a comparative example 4 where the particle size distribution shown in Table 5 used in Example 3 and a filler mixed with 30% by mass of silica sand of alkali content and 70% by mass of chromite sand are used, the natural porosity is Measured and shown in Table 6.

* Since Comparative Example 2 was very poor in pore-opening property, the test was stopped after being used twice.
Comparative Example 1 has the same characteristics as silica sand developed by the prior art, and a high hole opening rate was obtained under light smelting conditions, but the natural hole opening rate greatly deteriorated under heavy smelting conditions with more severe heat conditions. .

  In Examples 1 and 2, there was no difference in the natural hole ratio compared to Comparative Example 1 under the light refining conditions, but the natural hole opening ratio was greatly improved with respect to Comparative Example 1 under the heavy refining conditions. Compared with, the deterioration of the natural hole area rate was slight.

  On the other hand, in Comparative Example 2, serious opening failure occurred from the first use, and the test was terminated after two use. This is thought to be because the alkali amount of the second silica sand was extremely small and the compounding ratio was excessively increased, so that the coefficient of thermal expansion increased and a strong shelf suspension blockage occurred in the upper nozzle.

  Further, in Comparative Example 3, the natural hole area ratio under light refining conditions was slightly worse, and further deteriorated under heavy refining conditions. This is considered due to the sintering of the second silica sand.

  In Comparative Example 4, a high hole opening rate was obtained under the light refining conditions, but the natural hole opening rate was greatly deteriorated under the heavy refining conditions with more severe heat conditions. Moreover, in this comparative example, it has the subject that the chromite sand for which it is desired to reduce the usage-amount is used.

  Furthermore, as shown in FIG. 2, the lower layer in the nozzle was filled with a filler mixed with 30% by mass of silica sand and 70% by mass of chromite sand, and 30 kg of the silica sand of Example 2 was raised and used in the upper layer. In the form of Example 3, a very high natural hole area ratio was obtained under both light and heavy refining conditions.

  From the above result, it consists of 80-50 mass% of 1st silica sand containing 0.5 mass% or more of alkali content, and 20-50 mass% of 2nd silica sand whose alkali content is less than 0.5 mass%. It has been clarified that the filler is a filler for ladle sliding opening and closing devices that can meet more stringent refining conditions.

It is a graph which shows an example of the particle size distribution of the filler of this invention. It is the schematic of the sliding opening / closing apparatus used in the Example. It is the schematic of the sliding opening / closing apparatus used in the Example.

Explanation of symbols

A Inflection point, 1 filler, 2 bricks, 3 upper nozzle, 4 fixed plate, 5 sliding plate, 6 lower nozzle, 1a filler upper layer, 1b filler lower layer

Claims (5)

It consists of 80 to 50% by mass of the first silica sand having an alkali content of 0.8 to 1.4% by mass and 20 to 50% by mass of the second silica sand having an alkali content of 0 to 0.05% by mass,
The first silica sand contains 90% by mass or more of silica sand having a particle size distribution of 0.6 to 1.7 mm and 50% by mass or more of silica sand having a particle size distribution of 0.85 to 1.7 mm, The ladle comprises 90% by mass or more of silica sand having a particle size distribution of 0.212 to 0.85 mm and 50% by mass or more of silica sand having a particle size distribution of 0.212 to 0.6 mm. Filling material for sliding switchgear. The ladle sliding opening / closing device according to claim 1 , wherein the ladle sliding opening / closing filler is a filler used for molten steel refining at a steel receiving temperature of 1,660 ° C or higher and a molten steel holding time of 100 minutes or longer. Filler for equipment. The ladle sliding opening and closing device according to claim 1 or 2 , wherein the first silica sand is a mixed sand of feldspar and silica sand containing 80% by mass or more of sand having a particle size distribution of 0.6 to 1.7 mm. Filler. The filler for ladle sliding switchgear according to any one of claims 1 to 3 , wherein the first silica sand and the second silica sand have a particle shape factor of 1.4 or less. The first silica sand, the second silica sand, or the first silica sand and the second silica sand are 0.05 to 1.0% by mass of carbon by external addition, or the entire surface or a part of the surface. The filler for ladle sliding opening / closing device according to any one of claims 1 to 4 , wherein is a silica sand coated.

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