JP5312089B2 - Ladle with excellent residual steel reduction - Google Patents

Description

  The present invention relates to a ladle that is excellent in reducing remaining steel.

Conventionally, ladle used in the steelmaking process receives molten steel from the converter and transports it to the secondary refining process, or transports molten steel that has finished the secondary refining process to the continuous casting process. It is used. Thus, since the ladle is widely used over primary refining-secondary refining-continuous casting, it is the actual situation that various devices are made to the refractory constructed inside. For example, when receiving the molten steel from the converter, the refractory at the bottom of the ladle is more easily consumed than the other parts because it receives the molten steel falling from above.
Then, paying attention to this point, the technique of raising beforehand the refractory of the bottom part of a ladle is disclosed (for example, patent document 1, patent document 2).

In patent document 1, the hot water dropping part of the bottom part of a ladle is made into the convex shape curved smoothly, so that the lifetime of a hot water dropping part may become long.
In Patent Document 2, a part of the ladle laying part, which is severely damaged by molten steel, in particular, a so-called hot water hitting part where a steel flow from a steelmaking furnace collides has a refractory structure in order to have a brick jointless structure. Precast blocks are placed and raised.
As shown in Patent Document 1 and Patent Document 2, although the hot water falling part and the hot water hitting part where the molten steel from the converter collides are not convex, Patent Document 3 assumes that the bottom of the ladle is raised. There is something to show. Patent Document 3 discloses that the hot water contact portion of the floor portion is raised by 150 mm to 380 mm with respect to the layer thickness of 230 mm of the irregular refractory layer.

Japanese Utility Model Publication No.59-85667 JP 9-174230 A JP-A-9-141419

Patent Document 1 and Patent Document 2 disclose that the hot water drop portion and the hot water contact portion are convex, thereby prolonging the life in the part of the refractory that the molten steel collides with. There is no detailed description of the size of the hot water contact area, and the fact is that these techniques cannot be used in actual operations.
On the other hand, although Patent Document 3 discloses the size of the convex portion provided at the bottom of the ladle, the size is not defined from the viewpoint that the molten steel collides, so this technique may be used. The reality is that you can't.

  Then, in view of the said problem, this invention aims at providing the ladle excellent in the remaining steel reduction by prescribing | regulating the magnitude | size about the hot water contact part which a molten steel collides.

In order to achieve the above object, the present invention has taken the following measures.
That is, the technical means for solving the problems in the present invention is a ladle that is excellent in reducing the remaining steel, prevents the refractory from being peeled off, and prevents the defective opening of the nozzle for injecting molten steel. Regarding the inner surface of the bottom of the pan, the hot water impingement portion where the molten steel charged from the upper side collides is a circular portion that is higher than the other bottom when the construction of the refractory is completed, and the height of the circular portion is In addition to being 105 mm to 120 mm, the radius of the circular portion is 800 mm to 900 mm, and the distance from the end of the circular portion to the end of the injection hole is 1000 mm to 1200 mm.
The inventor examined the situation of the bottom in the steel making process, and when the molten steel charged from the upper side repeatedly hits the bottom, such as when the steel was discharged from the converter, the bottom gradually became concave, It was found that the size gradually increased. Here, the inventor has further investigated not only the conventional viewpoint of extending the life of the refractory but also other influences due to the formation of the recess.

As a result, it was found that when the concave portion gradually increased, when the molten steel flowed out from the ladle, the molten steel accumulated in the concave portion could not flow out, and the amount of molten steel remaining in the ladle increased.
Therefore, the inventor examined the size of the hot water contact portion from the viewpoint of reducing the amount of remaining steel in the molten steel, and determined that the hot water contact portion was a circular portion higher than the other bottom portion, and the height of the circular portion. Is set to 105 mm or more and 120 mm or less, the radius of the circular part is set to 800 mm or more and 900 mm or less, and the distance from the end of the circular part to the end of the injection hole is set to 1000 mm or more and 1200 mm or less, so that the remaining steel amount is as much as possible. I found that I can do less.

Moreover, in the verification of the size of the hot water contact part, not only the amount of remaining steel in the remaining steel is reduced, but also there is no occurrence of defective opening when the hot metal contact part (bottom part) is peeled off or the molten steel flows out. did.
In addition, since the problem as described above occurs in a ladle having a capacity (amount of molten steel stored) of 200 ton or more and 300 ton or less, this type of ladle is targeted.

  According to the present invention, it is possible to reduce the remaining steel without causing peeling of the hot water contact part or defective opening when the molten steel flows out.

The steel making process is shown. It is the figure which showed the cross-sectional side view of a ladle. It is a top view of a ladle. It is a figure which shows the state after use of a ladle.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a steel making process in which the ladle according to the present invention is used.
As shown in FIG. 1, the steelmaking process includes a primary refining process for decarburizing the molten metal, and separation and flotation of inclusions and component adjustment with respect to the molten metal (molten steel) that has been processed in the primary refining process. It consists of a secondary refining process to be performed and a continuous casting process for casting the molten metal that has been processed in the secondary refining process. The ladle 1 of the present invention is used in the primary refining process, the secondary refining process, and the continuous casting process. The ladle 1 in which the molten steel is emptied after the continuous casting process is returned to the primary refining process and used again. Will be. If the cycle from the primary refining process to the continuous casting process is one cycle, the number of uses of the ladle 1 is 80 cycles to 90 cycles.

In the primary refining process, after the decarburization process of the molten metal is completed in the converter 2, the molten steel after the decarburization process is completed. At this time, molten steel is received by the ladle 1 of the present invention, and conveyed to the secondary refining process by the ladle 1. In the secondary refining process, fine adjustment of components and floating separation of inclusions are performed on the molten steel in the ladle 1 in the secondary refining apparatus 3 such as an RH apparatus, an LF apparatus, and a CAS apparatus. When the secondary refining process is completed, the ladle 1 containing molten steel is conveyed to the continuous casting process.
In the continuous casting process, the ladle 1 conveyed from the secondary refining process is arranged on the upper side of the tundish 5 of the continuous casting apparatus 4, and the molten steel in the ladle 1 is charged into the tundish 5. The molten steel in the tundish 5 is poured into the mold 6 to cast the molten steel. When the molten steel in the ladle 1 is emptied in the continuous casting process, the ladle 1 is transported to the primary refining process, that is, the converter 1 and receives the molten steel discharged from the converter 1 in the primary refining process. Steel.

Hereinafter, the ladle 1 of the present invention will be described in detail.
As shown in FIGS. 2 and 3, the ladle 1 whose capacity (amount of molten steel is stored) is 200 ton or more and 300 ton or less. The ladle 1 is mainly composed of a bottomed iron skin 10 constituting the main body of the ladle 1 and a refractory 11 constructed on the iron skin 10. An arrow A in FIG. 2 shows the trajectory of the molten steel when the molten steel is taken out from the converter 1 into the ladle 1.
The iron skin 10 is roughly divided and includes a bottom wall portion 12 having a circular shape and a body wall portion 13 rising from the bottom wall portion 12 in one direction (for example, upward). A fixed refractory (refractory brick) 14 is provided on the bottom wall portion 12, and an irregular refractory 15 is provided on the inner surface side of the fixed refractory 14. The bottom 16 of the ladle 1 is formed by the bottom wall 12 of the iron shell 10, the regular refractory 14 provided on the bottom wall 12, and the irregular refractory 15 provided on the inner surface side of the regular refractory 14. It is configured. The body wall portion 13 is also provided with a regular refractory, and an irregular refractory is provided on the inner surface side of the regular refractory. Moreover, the refractory provided in the trunk wall part 13 and the bottom wall part 12 may be the regular refractory 14 or the irregular refractory 15, and the order and type thereof are not limited.

In the bottom portion 16 of the ladle 1, an injection hole 17 configured by penetrating the bottom portion 16 is provided. For example, the injection hole 17 is used when pouring molten steel into a tundish or the like, and penetrates the bottom wall portion 12 and the regular refractory 14 and the irregular refractory 15 provided on the bottom wall portion 12. Configured.
Regarding the inner surface side of the bottom portion 16 in the ladle 1, a circular shape (hereinafter referred to as a circular portion) in which a portion 20 (hereinafter referred to as a hot water hitting portion 20) where molten steel charged from above collides is higher than the other bottom portion 16. There is).

As shown in FIG. 2, the hot water contact portion 20 is a portion where the molten steel falling from above directly collides when the molten steel is discharged from the converter 1. In this embodiment, since the molten steel that has fallen on the central portion of the bottom portion 16 collides, the central portion is used as the hot water contact portion 20. The circular hot water contact portion 20 (the circular portion) is formed by raising the vicinity of the center of the amorphous refractory 15 provided on the bottom wall portion 12 of the iron shell 10 into a circular shape. Yes. In this embodiment, the upper surface after raising is flat at a certain height.
Further, in this embodiment, when the hot water contact portion 20 is viewed in plan, the center of the hot water contact portion 20 coincides with the center of the ladle 1. The position shifted in the radial direction from the center of the pan 1 may be used, and the position of the hot water contact portion 20 is not limited to the position shown in FIGS.

At the time when the construction of the refractory is finished (immediately after the construction of the hot water contact portion 20), the height h of the circular portion (the hot water contact portion 20) is 105 mm or more and 120 mm or less. The height h of the circular portion is the height of the portion where the irregular refractory 15 is raised (step difference between the hot water contact portion 20 and the non-hot water contact portion 21 where the hot water contact portion is not formed).
If the height h of the hot water contact portion 20 is less than 105 mm, when the number of uses of the ladle 1 increases, a dent (a dent in which molten steel accumulates) is also formed in the hot water contact portion 20, and The effect tends to decrease and the amount of remaining steel tends to increase.

On the other hand, when the height h of the circular portion (hot water contact portion 20) exceeds 120 mm, when the molten steel from the converter 1 is received in the initial stage where the number of times of use of the ladle 1 is small, the irregular shape is obtained. The refractory 15 is easily peeled off.
At the time when the construction of the refractory is finished, the radius R of the circular portion (hot water contact portion 20) is 800 mm or more and 900 mm or less. If the hot water hitting portion 20 is less than 800 mm, the hot water hitting portion 20 is too small, so when the molten steel is received, the molten steel collides with a portion other than the hot water hitting portion 20 (non-hot water hitting portion 21), A dent is generated in a portion other than the hot water contact portion 20 (non-hot water contact portion 21), and the amount of remaining steel tends to increase.

  On the other hand, when the radius R of the circular portion (hot water contact portion 20) is larger than 900 mm, the hot water contact portion 20 is too large. Therefore, as shown by the arrow B in FIG. However, there is a slight time difference between the time spreading over the entire hot water hitting portion 20 and the time spreading across the entire hot water hitting portion 21. That is, when the radius R of the circular portion is larger than 900 mm, when receiving the molten steel, the temperature of the bottom portion 16 is not uniform between the hot water contact portion 20 and the non-hot water contact portion 21 or hot water contact when the entire temperature distribution is viewed. Temperature non-uniformity is likely to occur in the portion 20, and the refractory (unshaped refractory 15) is likely to be peeled off due to variations in temperature distribution.

When the construction of the refractory is finished, the linear distance (distance between the injection holes) from the end portion (outer edge portion) 21a of the circular portion (hot water contact portion 20) to the end portion (outer edge portion) 17a of the injection hole 17 is called. L) is not less than 1000 mm and not more than 1200 mm. In other words, the inter-injection hole distance L is the shortest horizontal distance from the boundary between the hot water contact portion 20 and the non-hot water contact portion 21 to the upper end portion 17a of the injection hole 17.
If the distance L between the injection holes is less than 1000 mm, the distance between the circular portion (hot water contact portion 20) and the injection hole 17 is too short, so that the molten steel flowing from the circular portion toward the injection hole 17 is vigorously injected. Therefore, the filling sand blocking the injection hole 17 may be washed out. As a result, when the ladle 1 is installed in the continuous casting apparatus 4 and molten steel is injected into the tundish 5, the molten steel does not flow out of the injection hole 17 even if the nozzle 22 provided in the injection hole 17 of the ladle 1 is opened. Opening defects may occur.

  On the other hand, if the distance L between the injection holes is greater than 1200 mm, the distance between the circular portion (hot water contact portion 20) and the injection hole 17 is too long, so the molten steel near the center of the hot water contact portion 20 It takes some time to flow through the portion 20 toward the injection hole 17. That is, when the distance L between the injection holes is larger than 1200 mm, the temperature of the injection hole 17 is lower than the temperature of the hot water contact part 20 when the entire temperature distribution of the bottom part 16 is seen when receiving the molten steel. Inhomogeneity is likely to occur, and as a result, the molten steel in the vicinity of the injection hole 17 tends to harden and an opening defect may occur.

  Tables 1 and 2 summarize examples when the ladle 1 of the present invention is used and comparative examples when the ladle 1 of the present invention is not used.

In the examples and comparative examples, the amorphous refractory 15 in the bottom portion 16 including the hot water contact portion 20 has an alumina (Al ₂ O ₃ ) weight ratio of 88 to 92% and a silica (SiO ₂ ) weight ratio of 1 to 1. 3%, magnesia (in the table using a weight ratio of 5-7% of those skilled in the art regular use (castable) of (MgO), castable in MgO, castable in SiO _2, castable in Al ₂ O _3, other in castable ).
The castable thickness in the table indicates the thickness of the amorphous refractory 15 in the portion excluding the hot water perimeter (the portion excluding the hot water perimeter in the bottom 16).

In Examples and Comparative Examples, the slag and bullion remaining inside are discharged to the outside by inverting the ladle 1 after use, and after cooling, this is separated into slag and bullion, and only the bullion is weighed. The amount of remaining steel was calculated. And in an Example and a comparative example, when the amount of remaining steel increased with the increase in the use frequency of the ladle 1, there was an increase in the amount of remaining steel in the ladle 1 and it did not change (the increase did not progress). No.) No increase in remaining steel in ladle (In the table, there is an increase in remaining steel in ladle 1, “×”, “O”).
In Examples and Comparative Examples, when the molten steel does not flow out from the injection hole 17 even when the nozzle 22 of the ladle 1 is opened, there is an occurrence of defective opening, and when the molten steel flows out when the nozzle 22 is opened, no defective opening occurs. (In the table, the occurrence of defective opening, presence “×”, absence “◯”). In the case of a defective opening, the operator (operator) uses oxygen pipes or the like to cause oxygen to flow into the nozzle 22 to dissolve the bullion that has obstructed the molten steel flow inside the nozzle 22. It was leaked using a compulsory method.

As shown in FIG. 4, the ladle 1 checked the state of the refractory after each use, and visually confirmed whether the refractory on the laying portion (bottom 16) had peeled off. The refractory material (unshaped refractory 15) in the laying part (bottom part 16) was peeled off, and the laying part was peeled off, and the refractory was not peeled off (the peeling of the laying part in the table). , Yes “×”, No “○”).
In addition, in the continuous casting process, the ladle 1 was arrange | positioned on the upper side (on the installation stand 25) of the tundish 5 of the continuous casting apparatus 4 like a person skilled in the art, and molten steel was poured from the ladle 1 concerned. In addition, on the installation table 25, the ladle 1 is tilted toward the nozzle 22 (injection hole 17) so that the molten steel in the ladle 1 gathers in the injection hole 17 and easily flows out of the injection hole 17. The inclination angle of the ladle 1 is at most 2 degrees.

As shown in Examples 1 to 18, the hot water contact portion 20 is a circular portion, the height h of the circular portion is 105 mm or more and 120 mm or less, the radius R of the circular portion is 800 mm or more and 900 mm or less, and the circular portion If the distance from the end of the ladle to the end of the injection hole 17 is 1000 mm or more and 1200 mm or less, even if the number of uses of the ladle 1 is increased, there is no tendency for the remaining steel of the ladle 1 to increase, and the opening failure Also, no refractory peeling occurred at the bottom 16 (in the table, the remaining steel in the ladle increased, evaluation “◯”, defective opening, evaluation “◯”, laying peeling, evaluation “◯”).
On the other hand, as shown in Comparative Example 19 and Comparative Example 21, when the height h of the circular portion is less than 105 mm, the remaining steel of the ladle 1 tends to increase as the number of uses of the ladle 1 increases. (In the table, the remaining steel in the ladle increased, evaluation “×”). Moreover, as shown in Comparative Example 20, Comparative Example 22 and Comparative Example 23, when the height h of the circular portion exceeded 120 mm, refractory peeling occurred at the bottom 16 (in the table, peeling of the laying portion, evaluation) "X").

As shown in Comparative Example 24, Comparative Example 26, and Comparative Example 28, when the radius R of the circular portion is less than 800 mm, the remaining steel of the ladle 1 tends to increase as the number of uses of the ladle 1 increases. (In the table, the remaining steel in the ladle increased, evaluation “×”). Further, as shown in Comparative Example 25 and Comparative Example 27, when the radius R of the circular portion exceeded 900 mm, the refractory was peeled off at the bottom 16 (in the table, peeling of the laying portion, evaluation “×”).
As shown in Comparative Example 29 and Comparative Example 32, when the distance from the end of the circular portion to the end of the injection hole 17 exceeded 1200 mm, an opening failure occurred (in the table, the occurrence of an opening failure, evaluation “x”). ). As shown in Comparative Example 30, Comparative Example 31, and Comparative Example 33, an opening failure occurred when the distance from the end of the circular portion to the end of the injection hole 17 was less than 1000 mm (the occurrence of an opening failure in the table). , Rating "x").

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Ladle 2 Converter 3 Secondary refining apparatus 4 Continuous casting apparatus 5 Tundish 6 Mold 10 Iron skin 11 Bottom wall part 12 Body wall part 13 Shaped refractory 14 Amorphous refractory 15 Bottom 16 Injection hole 20 Hot water contact part 21 Non-bath area 22 nozzle

Claims (1)

In the ladle whose capacity is 200 ton or more and 300 ton or less and used in the steel making process,
Regarding the inner surface of the bottom portion of the ladle, the hot water impingement portion where the molten steel charged from above collides with the circular portion made higher than the other bottom portion when the construction of the refractory is finished ,
The height of the circular part is 105 mm or more and 120 mm or less, the radius of the circular part is 800 mm or more and 900 mm or less, and the distance from the end of the circular part to the end of the injection hole is 1000 mm or more and 1200 mm or less. A ladle that is excellent in reducing the remaining steel and prevents the refractory from peeling off and prevents the nozzle from injecting molten steel from being defectively opened .