Steam aging method of steel making slags and treatment pit of steel making slags

Abstract

To provide a method and a treatment pit capable of conducting steam aging of steel making slags.SOLUTION: In a method of conducting steam aging to steel making slags by feeding steam into a slag layer formed by stacking steel making slags in a treatment pit to a predetermined packing height from under the slag layer, a steam aging method of steel making slags is characterized by that, among the insides of the treatment pit, and in a predetermined region contacting with a retaining wall that the treatment pit includes, steel making slags are stacked in a manner that the height of steel making slags become higher than a predetermined packing height.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for steam aging of steelmaking slag and to a treatment pit for steelmaking slag. [Background technology]

[0002] One of the important issues is how to recycle the large amount of steelmaking slag generated from converters and other processes in the steelmaking process. Steelmaking slag is used as roadbed material and aggregate for roads, but because it contains free lime, it reacts with water, such as rainwater, and expands, which is a problem. When steelmaking slag is used for roads, it is stipulated that it must meet the specified expansion characteristics of JIS A5015 "Iron and Steel Slag for Roads" (expansion rate due to water immersion of 1.0% or less).

[0003] For this reason, before steelmaking slag is used as a roadbed material, it is usually subjected to an aging treatment in which the free lime is reacted with water to achieve a predetermined expansion characteristic. A widely known method for aging steelmaking slag efficiently is the steam aging method, which uses steam to promote the reaction with water at high temperatures.

[0004] As a technique for efficiently subjecting steelmaking slag to steam aging, Patent Document 1 discloses a technique in which water is added to the steelmaking slag until the water content reaches 10% by weight or more, and then steam aging is performed. Patent Documents 2 and 3 disclose techniques in which water is sprayed onto the steelmaking slag to uniformly apply water thereto, and then steam aging is performed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 8-12384 [Patent Document 2] Japanese Patent Application Publication No. 2017-149637 [Patent Document 3] Japanese Patent Application Laid-Open No. 2017-007880 Summary of the Invention [Problem to be solved by the invention]

[0006] In the steam aging process, steelmaking slag is typically piled up in a treatment pit, and steam is then circulated from the bottom of the pit into the pit to heat the steelmaking slag piled up in various parts of the pit. The variation δ in the temperature-raising time is one of the factors that increases the steam consumption rate (the amount of steam used to treat a unit weight of steelmaking slag). Therefore, to efficiently utilize steam during steam aging and improve the steam consumption rate, it is important to reduce the variation δ in the temperature-raising time. However, while Patent Documents 1, 2, and 3 are effective in improving the efficiency of steam aging by pre-heating the slag with water to promote the reaction beforehand and then contacting it with steam, they fail to address the variation δ in the temperature-raising time.

[0007] An object of the present invention is to provide a method and a treatment pit that can efficiently carry out steam aging of steelmaking slag. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention has the following features. That is, the present invention provides a method for steam aging steelmaking slag as set forth in the following [1] to [3], and a processing pit for steelmaking slag as set forth in [4] to [6]. [1] A method for steam-aging steelmaking slag by supplying steam from below the slag layer formed by piling steelmaking slag up to a predetermined filling height in a treatment pit, wherein the steelmaking slag is piled so that the height of the steelmaking slag is higher than the predetermined filling height in a predetermined area inside the treatment pit that is adjacent to the retaining wall of the treatment pit. [2] A method for steam aging steelmaking slag described in [1], wherein, inside the treatment pit, in a predetermined area adjacent to a first retaining wall provided in the treatment pit, steelmaking slag is piled so that the height of the steelmaking slag is higher than a predetermined filling height, thereby forming a raised portion above the slag layer, and when the distance between the first retaining wall and a second retaining wall provided in a position opposite the first retaining wall in the treatment pit is D, and the distance from the first retaining wall to the end of the raised portion on the side of the second retaining wall is d, the following formula (1) is satisfied. d≦0.2D (1) [3] A method for steam aging steelmaking slag described in [1] or [2], wherein, inside the treatment pit, in a predetermined area adjacent to a first retaining wall provided in the treatment pit, steelmaking slag is piled so that the height of the steelmaking slag is higher than a predetermined filling height, thereby forming a raised portion on the slag layer, and when the height of the slag layer at the center position of the treatment pit in the direction in which the second retaining wall provided in the treatment pit opposite the first retaining wall and the first retaining wall are aligned is H, and the height of the end of the raised portion on the first retaining wall side is h, the following formula (2) is satisfied. h≦0.5H (2) [4] A processing pit for steelmaking slag used for steam aging of steelmaking slag, comprising a slag layer formed by piling steelmaking slag up to a predetermined filling height within the processing pit, and a plurality of retaining walls that are in contact with the sides of the slag layer and extend higher than the predetermined filling height, and in a predetermined area within the processing pit that is in contact with a first retaining wall included in the plurality of retaining walls, steelmaking slag is piled so that the height of the steelmaking slag is higher than the predetermined filling height. [5] A processing pit for steelmaking slag described in [4], in which, inside the processing pit, in a predetermined area adjacent to the first retaining wall, steelmaking slag is piled so that the height of the steelmaking slag is higher than a predetermined filling height, thereby forming a raised portion above the slag layer, and when the distance between the first retaining wall and a second retaining wall provided in a position opposite the first retaining wall of the processing pit and the second retaining wall is D, and the distance from the first retaining wall to the end of the raised portion on the second retaining wall side is d, the following formula (1) is satisfied. d≦0.2D (1) [6] A processing pit for steelmaking slag described in [5] or [6], in which, inside the processing pit, in a predetermined area adjacent to the first retaining wall, steelmaking slag is piled so that the height of the steelmaking slag is higher than a predetermined filling height, thereby forming a raised portion above the slag layer, and when the height of the slag layer at the center of the processing pit in the direction in which the second retaining wall provided in the processing pit opposite the first retaining wall and the first retaining wall are aligned is H, and the height of the end of the raised portion on the first retaining wall side is h, satisfies the following formula (2). h≦0.5H (2) [Effects of the Invention]

[0009] According to the present invention, a method for steam aging steelmaking slag that can efficiently perform steam aging of steelmaking slag and a processing pit for steelmaking slag are realized. [Brief explanation of the drawings]

[0010] [Figure 1] This is a schematic diagram showing the configuration of a processing pit to which a method for steam aging of steelmaking slag according to one embodiment of the present invention is applied, and is a cross-sectional view seen from the direction in which the steelmaking slag is carried in. [Figure 2] FIG. 1 is a diagram showing particle size segregation that occurs near a retaining wall when steelmaking slag is piled up. [Figure 3] FIG. 1 is a diagram showing steam drift during steam aging due to particle size segregation of steelmaking slag. [Figure 4A] FIG. 10 is a diagram showing temperature measurement points in a conventional processing pit. [Figure 4B] FIG. 4B is a diagram showing temperature changes at each measurement point shown in FIG. 4A. [Figure 5A] FIG. 2 is a diagram showing temperature measurement points in the processing pit shown in FIG. [Figure 5B] FIG. 5B is a diagram showing temperature changes at each measurement point shown in FIG. 5A. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, a method for steam aging steelmaking slag according to one embodiment of the present invention (hereinafter referred to as this embodiment) will be described with reference to the accompanying drawings.

[0012] First, with reference to FIG. 1, the configuration of a treatment pit for steelmaking slag to which the steam aging method for steelmaking slag according to this embodiment is applied (hereinafter referred to as the treatment pit according to this embodiment) will be described. In the drawings, each component is shown somewhat simplified and schematic to make the explanation easier to understand, and the size (dimensions) of each component and the spacing between components shown in the drawings may differ from the actual ones.

[0013] In addition, in this specification, "inside the treatment pit" refers to the space where steam aging of steelmaking slag is carried out. Furthermore, in this specification, when describing the position, orientation, posture, etc. of each part of the processing pit, unless otherwise specified, the description will be of the position, orientation, posture, etc. when the processing pit is in its normal state (or, for ease of understanding, when steelmaking slag is piled up in the processing pit).

[0014] Furthermore, in this specification, "horizontal," "vertical," "orthogonal," and "parallel" include the range of error generally accepted in the technical field of the present invention, and also include states where the state is deviated from strictly horizontal, vertical, orthogonal, and parallel within a range of a few degrees or less (for example, 3° or less, preferably 2° or less if possible).

[0015] In the following description, the three mutually perpendicular directions are referred to as the X, Y, and Z directions. The Z direction is the up-down direction of the processing pit, and more specifically, corresponds to the vertical direction. The X and Y directions are directions perpendicular to the Z direction, i.e., horizontal directions, and the Y direction corresponds to the direction in which steelmaking slag is carried into the processing pit.

[0016] The treatment pit according to this embodiment (hereinafter referred to as treatment pit 10) is a facility used for steam aging of steelmaking slag. As shown in FIG. 1, the treatment pit 10 has a slag layer 12 formed by piling steelmaking slag up to a predetermined filling height in the treatment pit 10, and two retaining walls 14 (specifically, a first retaining wall 14A and a second retaining wall 14B) adjacent to the sides of the slag layer 12. The treatment pit 10 also has two raised portions 16 (specifically, a first raised portion 16A and a second raised portion 16B) formed by piling steelmaking slag in a predetermined area adjacent to the retaining wall 14 so that the height of the steelmaking slag is higher than the predetermined filling height.

[0017] Each component of the processing pit 10 will now be described. The slag layer 12 is formed in the treatment pit by stacking granular steelmaking slag 11 to a predetermined filling height H by normal stacking work on a bedding layer 20 in which steam pipes 18 that supply steam from pores are buried at predetermined intervals in the X direction. The procedure for forming the slag layer 12 is not particularly limited, but for example, the steelmaking slag 11 is transported from a stockyard into the treatment pit 10 using a transport device such as a belt conveyor or dump truck, and filled to the predetermined filling height H in the treatment pit 10, and the height of the filled steelmaking slag 11 is leveled to the predetermined filling height H (top leveling) using heavy machinery such as a shovel, thereby forming the slag layer 12.

[0018] The retaining wall 14 is a wall-like structure provided to prevent the collapse of the steelmaking slag 11 piled up in the treatment pit 10. The surface of the retaining wall 14 facing the inside of the treatment pit 10 (retaining wall surface 15) is flat, rises in the Z direction, and extends in the Y direction. The retaining wall surface 15 contacts the side surfaces of the slag layer 12 and the bulkhead 16 and supports the slag layer 12 and the bulkhead 16 from the sides by resisting the pressure (earth pressure) acting from these. In addition, the height of the retaining wall 14 is set to be higher than the height of the slag layer 12 (i.e., the specified filling height H), and where the bulkhead 16 is provided, it is set to be higher than the combined height of the slag layer 12 and the bulkhead 16.

[0019] As shown in Fig. 1, two retaining walls 14 are provided side by side with a gap in the X direction. In other words, the retaining wall 14 consists of a first retaining wall and a second retaining wall provided opposite the first retaining wall. The first retaining wall 14A and the second retaining wall 14B indicate the relative relationship between the two retaining walls 14; when the retaining wall 14 on the right side of Fig. 1 is viewed as the first retaining wall 14A, the retaining wall 14 on the left side corresponds to the second retaining wall 14B. Conversely, when the retaining wall 14 on the left side is viewed as the first retaining wall 14A, the retaining wall 14 on the right side corresponds to the second retaining wall 14B.

[0020] The number of retaining walls 14 is not particularly limited as long as there are at least two, and there may be three or more. Furthermore, the arrangement of the retaining walls 14 is not limited to being arranged side by side with gaps in the X direction, but when viewed in a plan view, if there are three retaining walls 14, they may be arranged in a U-shape with one end open in the Y direction, or if there are four retaining walls, they may be arranged in a square shape.

[0021] The bulky portion 16 is a characteristic feature of the present invention, and is formed by piling steelmaking slag 11 on the slag layer 12 in a predetermined area adjacent to the retaining wall 14 of the treatment pit 10 so that the height of the steelmaking slag 11 is higher than a predetermined filling height H. The procedure for forming the bulky portion 16 is not particularly limited, but for example, the steelmaking slag 11 is transported from a stockyard into the treatment pit 10 using a transport device such as a belt conveyor or dump truck, and the bulky portion 16 is formed by further piling steelmaking slag 11 on the slag layer 12 having a predetermined filling height H so that the further away from the retaining wall 14 the lower the height becomes.

[0022] As shown in FIG. 1, two raised portions 16 are provided so as to contact the two retaining walls 14, respectively. In other words, the raised portion 16 is composed of a first raised portion 16A provided so as to contact the first retaining wall and a second raised portion 16B provided so as to contact the second retaining wall. The first raised portion 16A and the second raised portion 16B indicate the relative relationship between the two raised portions; when the raised portion 16 on the right side of FIG. 1 is viewed as the first raised portion 16A, the raised portion 16 on the left side corresponds to the second raised portion 16B. Conversely, when the raised portion 16 on the left side is viewed as the first raised portion 16A, the raised portion 16 on the right side corresponds to the second raised portion 16B.

[0023] In other words, the number of bulkheads 16 can be equal to or less than the number of retaining walls 14 (excluding 0). Therefore, the number of bulkheads 16 is not particularly limited as long as it corresponds to the number of retaining walls 14. For example, in the case of Figure 1, there are two retaining walls, so there must be two or less bulkheads, and if there are three retaining walls, there must be three or less bulkheads, and if there are four or more retaining walls, there may be four or more bulkheads to match the number of retaining walls. Furthermore, the placement of the raised portion 16 is not particularly limited as long as it is provided so as to be in contact with the retaining wall 14 .

[0024] Here, if the distance between first retaining wall 14A and second retaining wall 14B in the X direction is D and the distance from first retaining wall 14A to the end of first bulky portion 16A on the side of second retaining wall 14B is d, it is desirable to satisfy the following formula (1): Distance d corresponds to the distance from one end to the other end of bulky portion 16 in the X direction, i.e., the width of bulky portion 16. (Number 1) d≦0.2D (1)

[0025] From the viewpoint of more effectively reducing the variation δ in the temperature rise time during steam aging, it is more desirable that d≦0.1D in the above formula (1).

[0026] Furthermore, if the height of the slag layer 12 at the center position of the treatment pit 10 in the X direction is H and the height of the end of the bulkhead 16 on the first retaining wall 14A side is h, it is desirable to satisfy the following formula (2): The height h corresponds to the height of the part of the bulkhead 16 where the steelmaking slag 11 is piled up the highest (specifically, the part in contact with the retaining wall 14), and is greater than 0. (Number 2) h≦0.5H (2)

[0027] Furthermore, in consideration of the convenience of the work of stacking the bulkhead 16 and safety after stacking, it is desirable that the bulkhead 16 be stacked lower the further it is from the retaining wall 14. In other words, it is desirable that the bulkhead 16 has a shape with a slope such that the angle of repose (the angle indicated by the symbol α in FIG. 1) after the steelmaking slag 11 is piled is within the range of a general angle of repose, specifically, 15°≦α≦60°.

[0028] The method for steam aging steelmaking slag according to this embodiment is a method for supplying steam from below the slag layer 12 to the slag layer 12 formed by piling steelmaking slag 11 up to a predetermined height H in the treatment pit 10 described above, and to the bulky upper portion 16 formed by piling steelmaking slag 11 on top of the slag layer 12 so that the height is higher than the predetermined height H. More specifically, steam is injected into the slag layer 12 from the bottom surface of the slag layer 12 from a steam pipe 18 buried in the bedding layer 20. As shown by the arrows in FIG. 1 , the steam passes through voids in the slag layer 12 from below and rises within the slag layer 12, coming into contact with and reacting with the free lime components of the steelmaking slag 11 that form the slag layer 12 and the bulky upper portion 16. This causes the steelmaking slag 11 to heat up and expand.

[0029] Next, the effect of the bulky portion 16 will be described. As shown in FIG. 4A, the conventional processing pit 50 is composed of components common to the processing pit 10 according to this embodiment, except for the bulky portion 16 of the processing pit 10 of the present invention. The present inventors have investigated and examined the steam aging to which such a conventional processing pit 50 is applied, and have found the following.

[0030] Generally, the particle size (particle diameter) of steelmaking slag particles used in steam aging treatment varies widely, from a few μm to 50 mm or more. The present researchers discovered that when steelmaking slag with such a wide particle size distribution is piled up in a treatment pit for steam aging, as shown in Figure 2, large particles of steelmaking slag 11 are unevenly distributed near the retaining wall 14, specifically in a specific area in contact with the retaining wall 14, while small particles of steelmaking slag 11 are unevenly distributed in the area away from the retaining wall surface 15 in the X direction, resulting in particle size segregation in the X direction.

[0031] When such particle size segregation occurs, in the region near the retaining wall 14 (retaining wall surface 15), particles of steelmaking slag 11 with large particle diameters exist in a state of point contact, as shown in Figure 2. On the other hand, in the region away from the retaining wall 14, particles of steelmaking slag 11 with small particle diameters exist in a state close to surface contact. Therefore, the voids between particles in the region near the retaining wall 14 tend to be larger than the voids between particles in the region away from the retaining wall 14 in the X direction. In other words, the void occupancy rate tends to be larger in the region near the retaining wall 14 than in the region away from the retaining wall 14.

[0032] Due to the difference in porosity within the slag layer 12 in the X direction as described above, steam drift can occur during steam aging. Figure 3 is a schematic diagram showing how steam, sprayed from a steam pipe 18 embedded in the bedding layer 20 onto steelmaking slag 11 stacked to a predetermined height in a treatment pit, passes through the steelmaking slag 11. As steam aging, i.e., the reaction between the steam and steelmaking slag 11, progresses, a condensed water layer 22 forms near the boundary between steelmaking slag 11A that has come into contact with the steam and reacted and steelmaking slag 11B that has not come into contact with the steam, moving from bottom to top. In each part of the treatment pit, steam aging is completed when the condensed water layer 22 reaches the uppermost steelmaking slag. On the other hand, as can be seen from the behavior of the moisture condensation layer 22 shown in Figure 3, steam passes through faster near the retaining wall 14, where the porosity of the voids S is large, than in areas away from the retaining wall 14 in the X direction, where the occupancy of the voids S is small (see arrows in Figure 3). Therefore, in the area near the retaining wall 14, steam reaches the steelmaking slag 11 on the surface (upper surface) of the slag layer 12 faster than in areas away from the retaining wall 14. Therefore, in the conventional treatment pit 50, steam aging is completed earlier in the area near the retaining wall 14 than in areas away from the retaining wall 14.

[0033] 4B is a graph showing the temperature change due to steam aging at each measurement point measured by installing multiple thermocouples on the surface of the slag layer 12 formed by piling up steelmaking slag 11 to a predetermined filling height H in the conventional treatment pit 50 shown in FIG. 4A. The vertical axis shows the temperature (°C) and the temperature change from 20°C (T0), and the horizontal axis shows the normalized elapsed time at each measurement point. The normalized elapsed time is the time elapsed from the start of the steam aging treatment, normalized by setting the time required for the temperature at all measurement points to a predetermined temperature (e.g., 100°C) after the start of the steam aging treatment as "1."

[0034] As shown in Figure 4A, when the distance between the first retaining wall 14A and the second retaining wall 14B in the X direction is D, the thermocouples are installed at the edge of one of the retaining walls 14 (measurement point P1), at a position 0.1D away from that retaining wall 14 (measurement point P2), at a position 0.25D away from that retaining wall 14 (measurement point P3), and at a position 0.5D away from that retaining wall 14 (measurement point P4), and the temperature during steam aging is measured continuously.

[0035] As shown in FIG. 4B, at each measurement point, the temperature rises as the steam passes through, and once it reaches a predetermined temperature (100°C), it is maintained at a constant value. It can also be seen that the time it takes for the steam to reach the surface (the time it takes to reach 100°C) varies depending on the distance from the retaining wall 14. In FIG. 4B, δ indicates the difference in time it takes to reach 100°C between measurement points P1 and P2 and measurement points P3 and P4 (variation in temperature rise time). It can be seen that steam reaches the surface faster in the surface layer near the retaining wall 14, where the proportion of voids S is large (see measurement points P1 and P2), than in the surface layer in an area away from the retaining wall 14, where the proportion of voids S is small (see measurement points P3 and P4), i.e., steam drift occurs.

[0036] Furthermore, in order to maintain quality, specifically, to allow the steam to react uniformly throughout the steelmaking slag 11, it is preferable to continue supplying steam from the steam pipe 18 buried in the bedding layer 20 until the steam reaches the surface layer in the area away from the retaining wall 14. In the surface layer near the retaining wall 14 (measurement points P1 and P2), even after the steam reaches the surface layer, it is necessary to continue supplying steam until the steam reaches the surface layer in the area away from the retaining wall 14 (measurement points P3 and P4) (see the variation δ in the temperature rise time in FIG. 4B). Therefore, it can be seen that steam aging using the conventional treatment pit 50 poses the problem of high steam consumption rate.

[0037] Therefore, the inventors focused on the steam drift that occurs as described above and decided to pile the steelmaking slag 11 in a predetermined area in contact with the retaining wall 14 of the treatment pit 50 so that the height of the steelmaking slag 11 is higher than a predetermined filling height H. More specifically, a bulky portion 16 is formed on the slag layer 12 in a predetermined area in contact with the retaining wall 14. This makes it possible to reduce the variation δ in the temperature rise time during steam aging for all the steelmaking slag piled in the treatment pit and reduce the steam consumption rate.

[0038] Furthermore, the inventors have discovered that when the bulk portion 16 of the processing pit 10 according to this embodiment has a shape that satisfies certain conditions such as equation (1), the variation δ in the temperature rise time during steam aging can be further reduced.

[0039] 5B is a graph showing the temperature change due to steam aging measured by installing multiple thermocouples on the surface of the slag layer 12 and the bulkhead 16 in the treatment pit 10 shown in FIG. 5A, i.e., the treatment pit 10 according to this embodiment (see FIG. 1). As in FIG. 4B, the vertical axis represents temperature (°C), and the horizontal axis represents normalized elapsed time.

[0040] The treatment pit 10 shown in Figure 5A has a raised portion 16 formed on the slag layer 12 of the conventional treatment pit 50 shown in Figure 4A. The raised portion 16 is formed by piling steelmaking slag 11 so that, when the distance between the first retaining wall 14A and the second retaining wall 14B is D, the distance from the end of the raised portion 16 on the first retaining wall 14 side to the end on the second retaining wall 14B side is d = 0.2D, the height of the raised portion 16 (strictly speaking, the height of the end on the side in contact with the retaining wall 12) is h = 0.3H, and the slope formation angle is 30°.

[0041] 5A, when the distance between the first retaining wall 14A and the second retaining wall 14B is D, thermocouples were installed at the edge of one of the retaining walls 14 (measurement point P1) on the surface of the slag layer 12, and at positions 0.1D (measurement point P2), 0.25D (measurement point P3), and 0.5D (measurement point P4) away from the retaining wall 14. Thermocouples were also installed at the edge of the retaining wall 14 on the surface of the bulkhead 16 (measurement point P5) and at positions 0.1D (measurement point P6) away from the retaining wall 14.

[0042] As can be seen from FIG. 5B, at each measurement point, the temperature rises as the steam passes through and remains constant once it reaches a predetermined temperature (100°C). Furthermore, steam reaches the surface of the slag layer 12 near the retaining wall 14 (see measurement points P1 and P2) earlier than the surface of the slag layer 12 in areas away from the retaining wall 14 (see measurement points P3 and P4). However, because the treatment pit 10 according to this embodiment includes a raised portion 16, there is almost no time difference between the time when steam reaches the surface of the raised portion 16 near the retaining wall 14 (see measurement points P5 and P6) and the time when steam reaches the surface of the slag layer 12 in areas away from the retaining wall 14. This indicates that the variation δ in the temperature rise time can be reduced in the treatment pit 10 according to this embodiment.

[0043] Furthermore, these results show that the timing at which the steam reaches the surface of the slag is closer between the area near the retaining wall 14 and the area away from the retaining wall 14, and the variation δ in the temperature rise time between the area near the retaining wall 14 and the area away from the retaining wall 14 is reduced. As a result, even after the steam reaches the surface of the slag layer 12 near the retaining wall 14, the supplied steam can be efficiently used for the steelmaking slag in the bulk portion 16 without being wasted. In other words, it is possible to reduce the steam consumption rate. Furthermore, from the above results, it can be seen that when the bulky portion 16 has a shape that satisfies predetermined conditions such as formula (1), the variation δ in the temperature rise time during steam aging can be further reduced.

[0044] The above describes one embodiment of the method for steam aging steelmaking slag and the processing pit for steelmaking slag of the present invention. However, the above embodiment is merely an example for facilitating understanding of the present invention and does not limit the present invention. In other words, the present invention can be modified and improved without departing from the spirit and scope of the present invention. Furthermore, it goes without saying that the present invention includes equivalents thereof. [Explanation of symbols]

[0045] 10. Processing pit for steelmaking slag 12 Slag layer 14 Retaining Wall 14A First Retaining Wall 14B Second retaining wall 15 Retaining wall surface 16 Bulk part 16A 1st bulky section 16B 2nd bulky part 18 Steam piping 20 Bedding layer 22 Moisture condensation layer S: Voids between particles

Claims

1. A method for steam aging steelmaking slag by supplying steam from below a slag layer formed by piling steelmaking slag up to a predetermined filling height in a treatment pit, the method comprising: A method for steam aging steelmaking slag, in which the steelmaking slag is piled in a predetermined area inside the treatment pit that is adjacent to a retaining wall of the treatment pit so that the height of the steelmaking slag is higher than the predetermined filling height.

2. Inside the treatment pit, in the predetermined region adjacent to the first retaining wall of the treatment pit, the steelmaking slag is piled up so that the height of the steelmaking slag is higher than the predetermined filling height, thereby forming a raised portion above the slag layer; a distance D between the first retaining wall and a second retaining wall provided in the treatment pit at a position facing the first retaining wall; A method for steam aging steelmaking slag as described in claim 1, wherein the following formula (1) is satisfied when the distance from the first retaining wall to the end of the raised portion on the second retaining wall side is d. d≦0.2D...(1)

3. Inside the treatment pit, in the predetermined region adjacent to the first retaining wall of the treatment pit, the steelmaking slag is piled up so that the height of the steelmaking slag is higher than the predetermined filling height, thereby forming a raised portion above the slag layer; The height of the slag layer at the center of the processing pit in the direction in which the second retaining wall provided in the processing pit at a position opposite to the first retaining wall and the first retaining wall are aligned is defined as H; A method for steam aging steelmaking slag as described in claim 1 or 2, wherein the following formula (2) is satisfied when the height of the end of the bulk portion on the first retaining wall side is h. h≦0.5H...(2)

4. A processing pit for steelmaking slag used for steam aging of steelmaking slag, comprising: a slag layer formed by piling the steelmaking slag in the treatment pit to a predetermined filling height; a plurality of retaining walls in contact with the sides of the slag layer and extending higher than the predetermined fill height; A processing pit for steelmaking slag, wherein in a predetermined area inside the processing pit adjacent to a first retaining wall included in the plurality of retaining walls, the steelmaking slag is piled so that the height of the steelmaking slag is higher than the predetermined filling height.

5. Within the treatment pit, in the predetermined region adjacent to the first retaining wall, the steelmaking slag is piled up so that the height of the steelmaking slag is higher than the predetermined filling height, thereby forming a raised portion above the slag layer; a distance D between the first retaining wall and a second retaining wall provided in the treatment pit at a position facing the first retaining wall; A processing pit for steelmaking slag as described in claim 4, which satisfies the following formula (1) when the distance from the first retaining wall to the end of the raised portion on the side of the second retaining wall is d. d≦0.2D...(1)

6. Within the treatment pit, in the predetermined region adjacent to the first retaining wall, the steelmaking slag is piled up so that the height of the steelmaking slag is higher than the predetermined filling height, thereby forming a raised portion above the slag layer; The height of the slag layer at the center of the processing pit in the direction in which the second retaining wall provided in the processing pit at a position opposite to the first retaining wall and the first retaining wall are aligned is defined as H; A processing pit for steelmaking slag as described in claim 5 or 6, which satisfies the following formula (2) when the height of the end of the raised portion on the first retaining wall side is h. h≦0.5H...(2)

Images