Slag aging method

Abstract

To provide a slag aging method with which it is possible to reduce variation in aging of slag by inhibiting variation in grain size and porosity of the slag at locations of a sediment different from each other even when the sediment is formed by stacking slags different in grain size and porosity in an aging processing facility, and with which it is possible to inhibit expansion of a product using the slag after aging.SOLUTION: An aging method for slag stacked in an aging processing facility 1, 10 includes: a calculation step of calculating at least one of a grain size and a porosity by sampling slag from at least two locations of at least one of the slag stacked in the aging processing facility 1, 10 and slag that forms a sediment 3; and an adjustment step of adjusting at least one of a grain size and tightness of the slag at a first location of two locations on the basis of at least one of the grain size and porosity of the slag.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for aging slag by hydrating the slag to suppress expansion of products using the slag, and more particularly to a method for aging the slag by steam. [Background technology]

[0002] In the steel industry, slag is produced as a by-product from processes such as blast furnaces, pretreatment processes (e.g., torpedo cars), converters, and electric furnaces. Among these, the slag produced from pretreatment processes, converters, and electric furnaces is specifically referred to as steelmaking slag. In the steelmaking process, a large amount of lime is added as an auxiliary material to remove phosphorus and silicon from molten pig iron. As a result, undissolved lime and lime crystallized during cooling remain in the steelmaking slag as free calcium oxide (f-CaO). This f-CaO undergoes hydration to form calcium hydroxide (Ca(OH)2), which expands in volume approximately twice that of f-CaO. Therefore, if the f-CaO in steelmaking slag hydrates and expands in volume, the steelmaking slag may pulverize, potentially resulting in a deviation in the particle size of the steelmaking slag from the specified size. Furthermore, there is a concern that the steelmaking slag may expand after shipping.

[0003] Applications of steelmaking slag include roadbed material and fine aggregate for concrete. In these applications, the volumetric expansion of f-CaO in steelmaking slag due to hydration can cause heaving of the roadbed and cracks in the concrete. Therefore, steelmaking slag used for these applications is required to meet the expansion characteristics specified in JIS A 5015. Currently, steelmaking slag is aged in air or steam before shipping to stabilize its volume. This reduces the risk of expansion and pulverization after shipping. Air aging refers to an aging method of steelmaking slag in which the moisture in the air hydrates the f-CaO in the slag by storing it for a long period of time in a slag yard or other facility. Steam aging refers to an aging method of steelmaking slag in which steam is supplied to the slag to cause the hydration reaction.

[0004] Patent Document 1 describes an example of a steam aging method, in which the state of steelmaking slag piled up in a steam aging facility is changed to age the slag while steam is being supplied to the slag. Specifically, multiple steam pipes and multiple gas pipes are buried in a permeable layer of the steam aging facility, and high-pressure air is blown in from the gas pipes to change the position of at least the fine slag with a small particle size among the steelmaking slag, thereby changing the path through which the steam passes. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-152601 Summary of the Invention [Problem to be solved by the invention]

[0006] Specifically, steelmaking slag generated in the steelmaking process is cooled and then crushed to a predetermined size. Furthermore, slag is roughly classified into various particle sizes and placed in temporary storage areas, including slag (hereinafter simply referred to as slag) to be piled up at a processing facility where slag is aged (hereinafter referred to as an aging processing facility) and slag of smaller particle sizes (hereinafter referred to as fine-grained slag). Conditions such as the amount of slag placed in the temporary storage area, the period for which the slag is placed, and the location of the temporary storage area vary, and particle size segregation of slag may occur even within the same temporary storage area. Therefore, there may be variations in the state of slag placed in different temporary storage areas or in different locations within the same temporary storage area, i.e., variations in the particle size and porosity of the slag. Therefore, if slag with such variations in grain size and porosity is piled up in an aging treatment facility to form a deposit, the deposit may also have portions with different grain size and porosity, i.e., variations in porosity. Therefore, if steam is supplied to the deposit, the steam may escape from the portions of the slag with a higher porosity than other portions, which may result in variations in the aging of the slag at different portions of the deposit.

[0007] The steam aging method described in Patent Document 1 changes the position of fine slag at the point in the deposit where high-pressure air is blown in, but it is not possible to suppress variations in the particle size and porosity of the slag throughout the deposit, and there is still room for improvement.

[0008] The present invention has been made to solve the above-mentioned problems, and aims to provide a slag aging method that can reduce variations in slag aging by suppressing variations in slag particle size and porosity at different locations in the deposit, even when slag of different particle sizes and porosities is piled up in an aging treatment facility to form a deposit, and that can suppress expansion of products using aged slag. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention provides: [1] A method for aging slag, in which steam is supplied to a deposit formed by stacking slag in an aging treatment facility to age the slag, comprising: a calculation step of sampling slag from at least two different locations on at least one of the slag to be stacked in the aging treatment facility and the slag forming the deposit, and calculating at least one of the particle size and porosity of the sampled slag; and an adjustment step of adjusting at least one of the particle size and compaction of the slag at a first location of the two locations based on at least one of the particle size and porosity of the slag calculated in the calculation step. [2] The slag aging method described in [1] above, wherein the sampled slag is slag to be loaded into the aging treatment facility. [3] A slag aging method as described in [2] above, wherein in the adjustment process, at least one of the particle size and compaction of the slag to be loaded into the aging treatment facility at the first location of the two locations is adjusted so that the difference between the porosities of the slag to be loaded into the aging treatment facility sampled from at least two different locations is less than 10%. [4] In the adjustment process, the pressure loss when steam is supplied to each of the sampled slag to be loaded into the aging treatment facility is estimated based on at least one of the particle size and porosity of the slag to be loaded into the aging treatment facility sampled from at least two different locations calculated in the calculation process, and at least one of the particle size and compaction of the slag to be loaded into the aging treatment facility at the first location of the two locations is adjusted so that the difference between the pressure losses is less than 1000 Pa / m, in the slag aging method described in [2] above. [5] The slag aging method described in [1] above, wherein the sampled slag is the slag forming the deposit. [6] A method for aging slag described in [5] above, wherein in the adjustment process, at least one of the particle size and compactness of the slag forming the deposit is adjusted so that the difference between the porosities of the slag forming the deposit sampled from at least two different locations is less than 10%. [7] In the adjustment step, the pressure loss when steam is supplied to each of the sampled slag forming the deposit is estimated based on at least one of the grain size and porosity of the slag forming the deposit sampled from at least two different locations calculated in the calculation step, and at least one of the grain size and compactness of the slag forming the deposit is adjusted so that the difference between the pressure losses is less than 1000 Pa / m, in the slag aging method described in [5] above. [8] A method for aging slag described in [2] above, wherein in the adjustment process, the average particle size of the slag stacked on the outer periphery of the deposit is adjusted so that it is equal to or smaller than the average particle size of the slag stacked outside the outer periphery of the deposit. [Effects of the Invention]

[0010] According to the present invention, it is possible to reduce the variation in the porosity of the slag at different locations in the pile. As a result, water vapor is less likely to escape from the pile as a whole, and the variation in the aging of the slag can be reduced. In addition, it is possible to suppress the expansion of products using aged slag. Furthermore, it is possible to reduce the loss of water vapor, i.e., the loss of energy. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view showing an example of an aging treatment facility. [Figure 2] FIG. 10 is a perspective view showing another example of an aging treatment facility. [Figure 3] FIG. 3 is a cross-sectional view showing a part of the aging treatment facility shown in FIG. 2. [Figure 4]1 is a flowchart illustrating a slag aging method according to a first embodiment of the present invention. [Figure 5] FIG. 1 is a diagram showing the relationship between slag porosity and pressure loss. [Figure 6] FIG. 10 is a diagram showing the relationship between the slag porosity and the flow rate ratio. [Figure 7] 5 is a flowchart illustrating a slag aging method according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] (First embodiment) Hereinafter, embodiments of the present invention will be described. The slag according to the present invention is a by-product of the steelmaking process and contains f-CaO. Examples of steelmaking processes that produce the slag include the steelmaking process, such as the preliminary treatment process and the refining process. Therefore, the slag is sometimes referred to as steelmaking slag. Because the slag contains f-CaO, it is piled in an aging treatment facility and aged to react the f-CaO with water to convert it to Ca(OH)2. In the slag aging method according to the present invention, steam is supplied from the bottom of the pile formed by piling the slag in the aging treatment facility, causing the f-CaO to react with water.

[0013] FIG. 1 is a cross-sectional view showing an example of an aging treatment facility. The aging treatment facility 1 shown in FIG. 1 has a permeation layer 2 that supplies steam to the slag, and the slag is piled on the permeation layer 2 to form a slag pile, or deposit 3. The means for piling the slag is not limited. For example, this means may be conventional heavy machinery such as a wheel loader or bulldozer. Furthermore, the shape of the deposit 3 is not limited. As shown in FIG. 1, the shape of the deposit 3 may be a frustum shape.

[0014] The permeation layer 2 supplies steam almost uniformly to the bottom surface of the slag deposit 3. A plurality of steam pipes 4 are buried in the permeation layer 2, and each steam pipe 4 is connected to a steam supply source (not shown). The steam supply source may be a conventionally known source such as a boiler.

[0015] The deposit 3 shown in Figure 1 has a truncated cone shape, and the outer surface of the deposit 3 is inclined downward. The angle between this inclined surface and the permeation layer 2 is approximately the same as the angle of repose of the slag. Slag grain size varies, and small-grained slag has lower fluidity than large-grained slag. Therefore, small-grained slag tends to remain where it is piled. In contrast, large-grained slag tends to flow from the piled area to the surrounding area. As a result, when slag is piled in the aging treatment facility 1, large-grained slag tends to accumulate on the outer periphery 5 of the deposit 3. Furthermore, the gaps between the slag particles on the outer periphery 5 of the deposit 3 are larger than those on the central portion 6 of the deposit 3 (the central portion of the deposit 3 in the left-right direction in Figure 1), which reduces the airflow resistance and makes it easier for water vapor to escape.

[0016] Walls may be provided around the aging treatment facility. Examples are shown in FIGS. 2 and 3. FIG. 2 is a perspective view showing another example of an aging treatment facility. FIG. 3 is a cross-sectional view showing a portion of the aging treatment facility shown in FIG. 2. The aging treatment facility 10 shown in FIGS. 2 and 3 has three walls 11a, 11b, and 11c. Of the three walls 11a, 11b, and 11c, two walls 11a and 11b are arranged at a predetermined interval and substantially parallel to each other. The remaining wall 11c is arranged between the two walls 11a and 11b in the width direction of each of the two walls 11a and 11b so as to connect one end to the other. In this way, a permeation layer 2 is formed in the space partitioned by the three walls 11a, 11b, and 11c.

[0017] The portion between the other ends of the two walls 11a, 11b in the width direction is an opening 12, as shown in Fig. 2, and the slag is transported and piled up in the space described above using the opening 12. When the slag pile 3 is formed in the space in this way, a portion of the pile 3 comes into contact with each of the three walls 11a, 11b, and 11c, as shown in Figs. 2 and 3.

[0018] As mentioned above, among the slag piled in the aging treatment facility 10, larger-grained slag has a higher fluidity than smaller-grained slag. Therefore, larger-grained slag tends to flow from the piled area to the surrounding area and accumulate near the walls 11a, 11b, and 11c and near the slopes of the deposit 3 facing the opening 12. Therefore, in these areas, the gaps between the slag are larger than in the central portion 6 of the deposit 3 (the center portion in the horizontal direction in FIG. 3 ), resulting in lower airflow resistance and easier escape of water vapor. In the example shown in FIGS. 2 and 3 , the areas near the walls 11a, 11b, and 11c, where larger-grained slag tends to accumulate, and the slopes of the deposit 3 facing the opening 12 correspond to the outer periphery of the deposit according to the present invention.

[0019] Furthermore, the vicinity of walls 11a, 11b, and 11c refers to a predetermined range from the walls 11a, 11b, and 11c. The vicinity of the inclined surface of the deposit 3 facing the opening 12 refers to the inclined surface and a predetermined range from the edge of the top surface of the deposit 3 on the opening 12 side toward the central portion 6. In other words, the above-mentioned locations are areas where steam tends to escape more easily due to the accumulation of large-grained slag, and as a result, steam tends to escape more easily than in the central portion 6. The above-mentioned locations can be determined in advance by experiment or calculation.

[0020] FIG. 4 is a flowchart illustrating a slag aging method according to a first embodiment of the present invention. The steelmaking slag generated in the steelmaking process (step S1) shown in FIG. 4 is temporarily accumulated and cooled in a slag cooling yard (not shown). The slag is then crushed to a predetermined size by a crusher (not shown). The slag is then roughly classified into various particle sizes, such as slag to be piled up in the aging treatment facility 1 and slag with a smaller particle size than the slag (hereinafter referred to as fine-grained slag), using a conventionally known method such as sieving, and placed in a temporary storage area (not shown).

[0021] The slag placed in the temporary storage area may have variations in slag particle size and porosity at different locations due to factors such as the amount of slag, the period for which the slag is placed, the location of the temporary storage area, and slag particle size segregation.

[0022] Therefore, in the first embodiment, slag stored in the temporary storage area is sampled from at least two different locations, and at least one of the grain size and porosity of each sampled slag is calculated (step S2, calculation process). Slag sampling may be performed from slag loaded on a transport vehicle (not shown) that transports slag from the temporary storage area to the aging treatment facility 1, 10, instead of from slag accumulated in the temporary storage area. In other words, in the first embodiment, the slag to be sampled is slag before it is loaded into the aging treatment facility 1, 10. In the following description, the location where sampling is performed may be referred to as the sampling point.

[0023] Furthermore, it is preferable to sample the slag by digging up, for example, about 50 cm from the surface of the slag. This is to avoid the influence of particle size segregation of the slag stored in the temporary storage area. In other words, it is to improve the accuracy of the particle size of the sampled slag and the measured and estimated values ​​of the porosity.

[0024] The method for measuring or estimating the particle size of slag is not limited. Conventional methods such as sieving may be used. Furthermore, the method for measuring or estimating the porosity of slag is not limited. For example, the porosity of slag may be measured or estimated with reference to the soil density test method using the sand displacement method specified in JIS A 1214 (revised March 21, 2013) or the aggregate unit volume mass and actual volume ratio test method specified in JIS A 1104 (revised March 25, 2019).

[0025] The frequency of slag sampling may be, for example, at least once every 50 tons or 100 tons of slag transported by a transport vehicle from the temporary storage area to the aging treatment facility 1. The grain size and porosity of the slag calculated in step S2 are temporarily stored in a storage device (not shown).

[0026] Next, based on at least one of the particle size and porosity of the slag calculated in step S2, at least one of the particle size and compaction of the slag at one of the two locations, i.e., the first location, is adjusted (step S3, first adjustment step). Note that in the present invention, "compactness" refers to the degree of compaction of the slag, and can be estimated from the wet density or dry density of the slag.

[0027] The following describes the process of adjusting the particle size of the slag at the first location. First, the difference in porosity and pressure drop between the slag at the two locations is calculated based on at least one of the particle size and porosity of the slag calculated in step S2. The particle sizes and porosities of the slag at the two locations calculated in step S2 are compared, and the one with the larger particle size and porosity is designated as the first location. Next, it is determined whether the difference in porosity or pressure drop between the two locations exceeds the upper limit values ​​described below. If the difference in porosity or pressure drop between the two locations exceeds the upper limit values, the particle size of the slag placed at the first location is adjusted, for example, so that it is less than the upper limit values. The slag at the first location after the adjustment and the slag at the other of the two locations, i.e., the second location, are then loaded into the aging treatment facility 1.

[0028] The upper limit of the difference between the above-mentioned porosities and the upper limit of the difference between the pressure losses will be explained below. The pressure loss is calculated based on the Ergun formula, which is represented by the following formulas (1) and (2).

[0029]

number

[0030] "ΔP / L" in the above formula (1) indicates the pressure loss per unit length when steam flows through the gaps between the slugs as a flow path. "u" indicates the flow velocity (m / s) of steam flowing through the gaps between the slugs as a flow path, and "ρf" is the gas density (kg / m 3 ), and "μf" represents the viscosity coefficient of water vapor (Pa·s). "ε" represents the porosity of the slag (%), "m" represents the number of components in the slag, and "Dpi" represents the particle size of the slag particles (m). "S" in the above formula (2) represents the specific surface area of ​​the slag (m 2 / g), "Φ" is the shape factor of the slag particles, and "Svi" is the volumetric mixture fraction (%). As shown in the above equations (1) and (2), the pressure loss (airflow resistance) is affected by various conditions such as the specific surface area S of the slag, the porosity ε, and the steam flow rate u, and among these parameters, the porosity ε has a particularly large effect.

[0031] Figure 5 shows an example of the relationship between the porosity ε (%) of slag and the estimated pressure drop. The pressure drop was estimated using slag of product particle size. Product particle size refers to the particle size (grain size) of slag suitable for shipping as a product. For example, it is a particle size that meets the CS40 standard specified in JIS A 5015 (standard name: steel slag for road use, revised December 20, 2018). The shape factor Φ of the slag particles was adjusted through preliminary testing to minimize discrepancies between the estimated and measured pressure drop values. As shown in Figure 5, when the difference between the porosity ε (%) at any two points exceeds 10%, the difference in pressure drop between those two points is approximately 300 Pa / m to 1000 Pa / m or more. This means that if the porosity ε (%) at one of these two points is more than 10% greater than the porosity ε (%) at the other point, the pressure drop at one point will suddenly decrease relative to the pressure drop at the other point, resulting in a loss of steam. In other words, this means that there is a possibility of variations in the aging of the slag.

[0032] Figure 6 shows an example of the relationship between the slag porosity ε (%) and the flow rate ratio. The flow rate ratio refers to the ratio of the estimated inflow steam volume to the minimum value (minimum inflow flow rate) of the steam volume flowing into the slag of the same lot. Figure 6 also uses a different lot and particle size from those used in Figure 5. As shown in Figure 6, when the difference between the porosity ε (%) at any two points exceeds 5%, the difference between the flow rate ratios at those two points also exceeds 5. This means that if the porosity ε (%) at one of those two points is greater than the porosity ε (%) at the other point by more than 5%, the estimated inflow steam volume at one point increases sharply relative to the estimated inflow steam volume at the other point, resulting in a loss of steam. This means that there is a possibility of variation in slag aging.

[0033] From these results, in order to suppress variations in slag aging, it is preferable that the difference between the porosity ε (%) at any two points be at least less than 10%. This numerical value is the upper limit of the difference between the above-mentioned porosities. It is more preferable that the difference between the porosity ε (%) be 5% or less. Alternatively, it is preferable that the difference between the pressure losses at any two points be less than 1000 Pa / m. This numerical value is the upper limit of the difference between the above-mentioned pressure losses. It is more preferable that the difference between the pressure losses be 500 Pa / m or less.

[0034] Returning to the explanation of the adjustment process in step S3, the grain size of the slag in the first location can be adjusted, for example, by adding or mixing fine slag to the slag. The amount of fine slag to be added to or mixed with the slag can be determined using a map that is prepared in advance and defines the relationship between the amount of fine slag and the porosity of the slag. The fine slag may be slag accumulated in a temporary storage area.

[0035] The following describes the case where the compaction of the slag at the first location is adjusted. The slag at the first location, which has a higher porosity than the slag at the second location, is compacted, for example, at a temporary storage site using heavy machinery or a roller. The compaction of the slag can be determined based on the hydraulic pressure measured when the slag is compacted using heavy machinery or a roller, or the change in the height of the slag pile before and after such work. That is, as the hydraulic pressure or the change in the height of the slag pile at the temporary storage site increases, the compaction and porosity of the slag decrease accordingly. Therefore, a map defining the relationship between the hydraulic pressure or change in pile height and the compaction of the slag, i.e., the porosity, can be prepared in advance, and the compaction of the slag can be determined and adjusted using this map. Alternatively, the slag from the two locations described above may be stacked adjacent to each other in the aging treatment facility 1 to form a pile 3, and the portion of the pile 3 where the slag from the first location is stacked may be compacted as described above to adjust the compaction of the slag.

[0036] Next, water vapor is supplied to the deposit 3 to perform aging for a predetermined time (step S4, aging step), and then the deposit 3 is shipped as a product (step S5, shipping step).

[0037] Therefore, according to the first embodiment, even if there are variations in the grain size and porosity of the slag placed in different locations in the temporary storage area, the variation in the porosity of the slag can be reduced for the entire deposit 3 formed in the aging treatment facility 1, 10. As a result, water vapor is less likely to escape from the entire deposit 3, and the variation in slag aging can be reduced. In addition, expansion of products using aged slag can be suppressed. Furthermore, water vapor loss, i.e., energy loss, can be reduced.

[0038] (Second embodiment) Fig. 7 is a flowchart illustrating a slag aging method according to a second embodiment of the present invention. The example shown in Fig. 7 is an example in which, instead of adjusting the grain size and compaction of the slag before it is loaded into the aging treatment facility 1, the grain size and compaction of the slag forming the deposit 3 are adjusted to reduce the variation in the porosity of the slag throughout the deposit 3. In Fig. 7, steps similar to those shown in Fig. 4 are designated by the same reference numerals as in Fig. 4, and their description will be omitted.

[0039] In the example shown in Figure 7, following step S1, slag is transported by a transport vehicle from the temporary storage site to the aging treatment facility 1, and the slag is piled up in the aging treatment facility 1. When a deposit 3 of a certain size is formed, slag is sampled from at least two different locations in the deposit 3, and at least one of the grain size and porosity of each sampled slag is calculated (step S2, calculation process). The method for calculating the grain size and porosity of the slag may be the same as the calculation method in step S2 described above.

[0040] In sampling slag from the deposit 3, it is preferable to perform sampling at regular intervals (for example, every 2 m) in the horizontal direction of the deposit 3. In addition, at least one of the two different sampling points is located on the outer periphery of the deposit 3 in the example of the aging treatment facility 1 shown in FIG. 5 2 and 3, it is preferable that the slag be near the walls 11a, 11b, and 11c or near the slopes facing the openings 12 in the deposit 3. This is because, as mentioned above, large-grained slag tends to accumulate in these locations, and therefore water vapor tends to escape easily.

[0041] Based on the slag particle size and porosity calculated in step S2, at least one of the particle size and compaction of the slag at the first location, which has a larger particle size and porosity than the second location, is adjusted (step S6, second adjustment step). The adjustment of the slag particle size in step S6 will now be described. Similar to the first embodiment, the difference in the porosity and pressure loss of the slag at each of the two locations is calculated based on at least one of the particle size and porosity calculated in step S2. Furthermore, the particle size and porosity of the slag at the two locations calculated in step S2 are compared, and the location with the larger particle size and porosity is designated as the first location. Next, it is determined whether the difference between the porosities or the difference between the pressure losses exceeds the upper limit values ​​described above. If the difference between the porosities or the difference between the pressure losses at the two locations exceeds the upper limit values, the particle size of the slag placed at the first location is adjusted so that the difference is less than the upper limit values.

[0042] Specifically, slag within a predetermined range, including the first location, is excavated, and fine slag is added to or mixed with the excavated slag. The amount of fine slag to be added to or mixed with the excavated slag can be determined using a map that defines the relationship between the amount of fine slag and the porosity of the slag, which map is prepared in advance. The fine slag may be slag accumulated in a temporary storage area. The addition or mixing of the fine slag may be performed using the heavy machinery described above, or may be performed manually.

[0043] The following describes the adjustment of the slag compaction in step S6. The slag at the first location, which has a higher porosity than the slag at the second location, is compacted using, for example, heavy machinery or a roller. The compaction of the slag can be determined based on the hydraulic pressure measured when the slag is compacted using heavy machinery or a roller, or the change in the height of the slag pile before and after such work. In other words, as the hydraulic pressure or the change in the height of the slag pile at the temporary storage site increases, the compaction of the slag, i.e., the porosity, decreases accordingly. Therefore, a map defining the relationship between the hydraulic pressure or change in pile height and the compaction of the slag, i.e., the porosity, can be prepared in advance, and the compaction of the slag can be determined and adjusted using this map.

[0044] Next, water vapor is supplied to the deposit 3 to perform aging for a predetermined time (step S4, aging step), and then the deposit 3 is shipped as a product (step S5, shipping step).

[0045] Therefore, even if slag with variations in particle size and porosity are piled up in the aging treatment facility 1 to form the deposit 3, the above-mentioned adjustments can reduce the variation in the porosity of the slag throughout the deposit 3. This makes it difficult for water vapor to escape throughout the deposit 3, reducing the variation in the aging of the slag. Furthermore, expansion of products using aged slag can be suppressed. Furthermore, water vapor loss, i.e., energy loss, can be reduced. In other words, the second embodiment can achieve the same effects as the first embodiment.

[0046] The present invention is not limited to the above-described embodiments. When slag is piled in the aging treatment facility 1, 10 to form the deposit 3, the areas where water vapor easily escapes due to particle size segregation are generally determined, as described above. Therefore, fine-grained slag may be piled in areas of the deposit 3 where water vapor easily escapes, such as the outer periphery 5, to suppress variations in the porosity of the slag throughout the deposit 3. Specifically, the average particle size of the slag piled in the outer periphery 5 is adjusted before piling so that the average particle size of the slag in the outer periphery 5 after the deposit 3 is formed is approximately the same as the average particle size of the slag in other areas. In other words, the average particle size of the slag piled in the outer periphery 5 is adjusted to be equal to or smaller than the average particle size of the slag piled in areas other than the outer periphery 5. Then, by piling the adjusted slag in the outer periphery 5, the average particle size of the slag in the outer periphery 5 is made approximately the same as the average particle size of the slag in other areas. This approach also achieves functions and effects similar to those of the above-described embodiments.

[0047] In each embodiment, the porosity of the slag in the entire deposit 3 may be adjusted by adding or mixing fine slag to the slag to be loaded in the aging treatment facility 1, 10 and adjusting the compaction of the slag to be loaded in the aging treatment facility 1, 10. Furthermore, the compaction of the slag may change compared to the time when the slag was sampled due to heavy machinery or manual operations when loading the slag in the aging treatment facility 1, 10. In such cases, the slag may be compacted (compacted) when being loaded, or fine slag may be added to adjust the porosity. This can prevent changes in the compaction of the slag, i.e., the porosity, caused by heavy machinery or manual operations during loading.

[0048] In the first embodiment, the particle size and porosity of the slag pieces before they are piled in the aging treatment facility 1 are compared, while in the second embodiment, the particle size and porosity of the slag pieces after they are piled to form the deposit are compared. However, it is also possible to sample both the slag pieces before and after they are piled, and compare the particle size and porosity of the slag pieces before and after they are piled. This also reduces the variation in the porosity of the slag pieces throughout the deposit 3.

[0049] (First Example) Next, an example conducted to verify the effectiveness of the present invention will be described. In this example, when slag was transported to the aging treatment facility by a transport vehicle, samples were taken every 50 tons of slag to measure the particle size and porosity of the transported slag. The particle size, compactness, and porosity of the slag were adjusted as described above so that the difference between the porosities of the sampled slag and the difference between the pressure drops were less than the upper limit values. The porosity of the slag was calculated using the sand displacement method specified in JIS A 1214. The maximum porosity difference, estimated steam inflow ratio (estimated value at the maximum and minimum porosities within the lot), lot average expansion rate, and standard deviation of the lot average expansion rate for each sample are summarized in Table 1.

[0050] [Table 1]

[0051] The maximum porosity difference refers to the difference between the maximum and minimum porosities of the slag within the same lot. The estimated steam ratio is the ratio of the maximum amount of steam flowing into the area with the maximum porosity (hereinafter referred to as the maximum inflow amount) to the minimum amount of steam flowing into the area with the minimum porosity (hereinafter referred to as the minimum inflow amount) within the same lot, calculated by dividing the maximum amount of steam flowing into the area with the minimum porosity (hereinafter referred to as the minimum inflow amount). The expansion characteristics of the slag were measured according to the method specified in JIS A 5015.

[0052] In Comparative Examples 1 to 3, after sampling the slag, deposits were formed in the same manner as in Examples 1 to 6, except that the slag grain size, compaction, and porosity were not adjusted. That is, in Comparative Examples 1 to 3, the slag was simply piled up in the aging treatment facility and aging treatment was carried out in that state. Note that Examples 1 to 6 and Comparative Examples 1 to 3 used different slag lots.

[0053] (evaluation) In Comparative Examples 1 to 3, the aging treatment was performed without adjusting the porosity, which resulted in variations in the aging of the slag, and both the lot average expansion coefficient and the standard deviation of the lot average expansion coefficient were larger than those of Examples 1 to 6. Furthermore, the estimated steam volume ratios differed by up to 10 points or more. This means that there was a large difference in the amount of steam inflow depending on the location where the slag was piled, which resulted in a large loss of steam.

[0054] On the other hand, in Examples 1 to 3, as shown in Table 1, the maximum porosity difference was about 5%, so the variation in the lot average expansion coefficient (%) was reduced compared to Comparative Examples 1 to 3. The estimated steam amount ratio was also reduced. In Examples 4 to 6, the maximum porosity difference was about 10%, so the variation in the lot average expansion coefficient (%) and the lot average expansion coefficient were slightly higher than in Examples 1 to 3. However, compared to Comparative Examples 1 to 3, the variation in the lot average expansion coefficient (%) was reduced, and the estimated steam amount ratio was also reduced. Thus, in Examples 1 to 6, steam can be supplied almost uniformly to the entire deposit 3 compared to Comparative Examples 1 to 3, so the variation in slag aging can be reduced and the expansion of products using the aged slag can be suppressed. [Explanation of symbols]

[0055] 1,10 Aging processing facility 2 Penetration layer 3 Sediment 4 Steam Pipes 5 Outer periphery of the deposit 6 Central part of the deposit 11a, 11b, 11c Wall 12 Opening

Claims

1. A slag aging method for aging slag by supplying steam to a deposit formed by piling slag in an aging treatment facility, comprising: A calculation step of sampling the slag stored in the temporary storage area before being loaded into the aging treatment facility and calculating the particle size and porosity of the sampled slag; an adjusting step of mixing the sampled slags placed in the temporary storage area with fine slags having a smaller particle size than the slags having a larger porosity, based on the particle size and porosity of the slags calculated in the calculating step, so that the difference in the porosity of the sampled slags is less than 10% if the difference is 10% or more; an aging step of stacking the slag that has been subjected to the adjusting step in the aging treatment facility to form the deposit, and supplying steam to the deposit to perform aging; A slag aging method in which the calculation step involves sampling the slag stored in the temporary storage area and transporting it from the temporary storage area to the aging treatment facility at least once every 100 tons.

2. A slag aging method for aging slag by supplying steam to a deposit formed by piling slag in an aging treatment facility, comprising: A calculation step of sampling the slag stored in the temporary storage area before being loaded into the aging treatment facility and calculating the particle size and porosity of the sampled slag; an adjusting step of estimating the pressure loss when steam is supplied to the sampled slag based on the particle size and porosity of the slag calculated in the calculating step, and mixing the sampled slag, which has a smaller particle size than the slag placed in the temporary storage area and has a smaller pressure loss, with the sampled slag placed in the temporary storage area so that the difference in the pressure loss between the sampled slags is less than 1000 Pa / m if the difference is 1000 Pa / m or more; an aging step of stacking the slag that has been subjected to the adjusting step in the aging treatment facility to form the deposit, and supplying steam to the deposit to perform aging; A slag aging method in which the calculation step involves sampling the slag stored in the temporary storage area and transporting it from the temporary storage area to the aging treatment facility at least once every 100 tons.

3. 3. A slag aging method according to claim 1 or 2, wherein in the aging process, the average particle size of the slag piled on the outer periphery of the deposit is equal to or smaller than the average particle size of the slag piled on a portion other than the outer periphery of the deposit.

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