JP2022038784A - Processing method of steelmaking slags, manufacturing method of slag products, and processing system of steelmaking slags - Google Patents

Abstract

To provide a processing method and a processing system of steelmaking slags capable of effective acceleration of aging even to slags which naturally become powdered.SOLUTION: A processing method of steelmaking slags includes aging treatment process of acceleration of aging of slags in a container 21 while stirring a blend M of water and slags and pulverizing slags in the blend M. Also, a processing system 10 of steelmaking slags includes a container 21 where a blend M of water and slags is stirred, and is assembled with a pulverization device 20 for stirring the blend M and pulverizing slags in the blend M in the container 21.SELECTED DRAWING: Figure 1

Description

The present invention relates to a slag treatment method and the like that promote aging of steelmaking slag.

Steelmaking slag discharged from converters, electric furnaces, etc. (hereinafter, may be referred to as "slag") contains free lime (f-CaO) and has expansion characteristics due to the hydration reaction of free lime. be. Therefore, when slag is used for roadbed materials and the like, an aging treatment is performed in which the expansion of free lime in the slag is promoted in advance so as not to cause an adverse effect due to expansion.

Further, when water-soluble calcium components such as free lime and calcium hydroxide come into contact with water such as rainwater, highly alkaline water elutes. When the calcium component contained in this highly alkaline water reacts with carbon dioxide in the atmosphere, calcium carbonate is generated and remains as a white precipitate after the evaporation of water, which causes problems such as spoiling the aesthetic appearance of the surroundings as white marks. It may occur. Therefore, a carbonation treatment may be performed in which the water-soluble calcium component contained in the slag is reacted with carbon dioxide in advance to insolubilize it.

Patent Document 1 describes a method for aging steelmaking slag. In this treatment method, steelmaking slag is artificially inflated in a short time by using steam, and the product is aged on an industrial scale to be applicable as a roadbed material for roads. In this treatment method, steelmaking slag at room temperature, which is crushed so that the particle size of 25 mm or less is 80% or more, is charged into the pressure vessel and the pressure vessel is sealed. Then, by supplying pressurized steam into the container to heat the container and the slag, the temperature and pressure inside the pressure vessel are raised and increased while the condensed hot water is discharged. Next, the inside of the vessel is kept in a saturated steam atmosphere at a pressure of 2 to 10 kg / cm ² G for 1 to 5 hours, and then the inside of the pressure vessel is depressurized to atmospheric pressure to discharge the steelmaking slag.

Further, Patent Document 2 describes a method of aging steelmaking slag with pressurized steam. In this treatment method, the steelmaking slag is directly hydrated by supplying steam to the steelmaking slag charged in the slag storage container via a pipe guided to the inside of the slag storage container.

Further, Patent Document 3 describes a method for treating steelmaking slag, which is subjected to carbonation treatment after aging treatment.

Japanese Unexamined Patent Publication No. 8-165151 Japanese Unexamined Patent Publication No. 2009-280445 Japanese Unexamined Patent Publication No. 2017-114717

By the way, high basicity slag such as stainless slag (slag containing a large amount of free lime, etc.) is several μm due to volume expansion due to phase transformation of the crystal structure during the cooling process from the molten state to room temperature. It is pulverized to a particle size of ~ several hundred μm. When the steam aging described in the above-mentioned patent documents is applied to such naturally pulverized slag, a water film is formed on the surface of the slag particles and the surface of the baby boom due to the condensation of water vapor, and the water film is formed. This hinders heat transfer and steam supply to the inside of the slag. Therefore, aging cannot be sufficiently promoted.

For this reason, conventionally, even if the powdered slag is further crushed, it is not possible to sufficiently contact the slag with water by the aging treatment as in the case before crushing, and the aging can be sufficiently promoted. It was thought that it could not be done. Therefore, high-basic slag is disposed of as slag that cannot be reused by a short-time aging treatment, such as landfill.

The present invention has been made in view of such circumstances, and provides a steelmaking slag treatment method and treatment system capable of effectively promoting aging even for slag that naturally pulverizes. The purpose is.

In addition, in this specification, "powdering" includes not only producing powder (particles of less than 1 mm) but also making the powder finer. Further, "high basicity (slag)" is a slag having a high basicity to the extent that pulverization occurs naturally, and as a guide, a slag having a basicity of 1.6 or more. Further, "aging" means that the hydration reaction of free lime in the slag proceeds.

The inventor of the present application observed the particles of slag, which expands in volume due to the hydration reaction, with a microscope. In the micrograph (FIG. 3) at a magnification of 1000 times, it was confirmed that powder of 1 μm or less adhered to the surface of the particles and a needle-like substance was formed. Furthermore, in the micrograph (Fig. 4) at a magnification of 5000 times, this needle-like object is in a state where a large number of extremely thin plate-like objects are laminated, and the surface of a single particle forms a narrow valley. It was confirmed that it had collapsed and left. From this observation result, the inventor of the present application discovered that the slag continues to be pulverized even when the slag is pulverized from a large mass of several hundred mm to several tens of μm. It was found that the hydration reaction was not completely completed no matter how fine the slag was, and the volume expansion continued for a long period of time. Based on this finding, the inventor of the present application has found that (i) pulverizing slag by pulverization has the same action as (ii) pulverizing by volume expansion and pulverization by a hydration reaction, and (ii) the number of particles by pulverization. As the specific surface area of each particle increases dramatically, the rate of hydration reaction in the entire slag also increases dramatically. In other words, slag pulverization was considered to be effective in promoting aging.

Based on this idea, the first invention is a method for treating steelmaking slag, which comprises an aging treatment step for promoting slag aging while stirring a mixture of water and slag and crushing the slag in a container. ..

According to the second aspect of the present invention, in the aging treatment step, water vapor is supplied below the liquid surface of the mixture during the stirring of the mixture and the crushing of the slag.

According to the third aspect of the present invention, in the aging treatment step, carbon dioxide gas is supplied below the liquid surface of the mixture during the stirring of the mixture and the pulverization of slag.

In the fourth invention, in any one of the first to third inventions, the slag in the mixture after the aging treatment step contains 60% by mass or more of particles having a particle size of 10 μm or less.

In the fifth aspect of the invention, in any one of the first to fourth inventions, in the aging treatment step, the slag is crushed by stirring the spheres together with the mixture in the container and causing the slags to collide with the slags. ..

In the sixth aspect of the invention, in any one of the first to fifth inventions, in the aging treatment step, the mixture is discharged from the container to the separation tank, and the slag that has settled to the bottom in the separation tank is returned to the container.

According to the seventh aspect of the invention, in the aging treatment step, the slag in which the mixture is discharged from the container to the separation tank and settles to the bottom in the separation tank is returned to the container together with water through a pipe.
In the piping, the water containing slag is cooled.

In the eighth invention, in the third or seventh invention, dry ice is supplied to the container when the temperature of the mixture in the container is lowered.

In the ninth invention, in the first invention, the container is used as the first container, and in the aging treatment step, water vapor or carbon dioxide gas under the liquid surface of the mixture during the stirring of the mixture and the crushing of the slag in the first container. One is supplied and the other of water vapor or carbon dioxide is supplied below the surface of the mixture during the stirring of the mixture and the crushing of the slag in the second container into which the mixture discharged from the first container flows.

The tenth invention includes a commercialization step of producing a slag product from a mixture after the aging treatment step in the treatment method of any one of the first to ninth inventions.

The eleventh invention is a steelmaking slag treatment system, comprising a container in which a mixture of water and slag is agitated, and a crushing device for stirring the mixture and crushing the slag in the mixture in the container.

In the present invention, the mixture of water and slag is stirred and the slag in the mixture is crushed in the container. Therefore, even if the slag in the mixture is powder, the water immediately comes into contact with the crushed surface (surface of the particles) of the slag. A hydration reaction is initiated on the crushed surface of the slag. Then, as described above, the crushing of the slag dramatically increases the number of particles and the specific surface area of each particle, so that the rate of the hydration reaction in the entire slag in the mixture also dramatically increases. Therefore, even if the slag is naturally pulverized, the aging treatment can be completed in a shorter time than before. Further, when the present invention is applied to other types of slag (slag that hardly naturally pulverizes), the aging treatment can be completed in a shorter time than before.

FIG. 1 is a schematic configuration diagram of a slag processing system according to an embodiment. FIG. 2 is a schematic configuration diagram of a slag processing system according to a modified example of the embodiment. FIG. 3 is a photomicrograph (magnification magnification 1000 times) of slag particles that expand in volume due to a hydration reaction. FIG. 4 is a photomicrograph (magnification magnification 5000 times) of slag particles that expand in volume due to a hydration reaction.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are examples of the present invention, and are not intended to limit the scope of the present invention, its applications, or its uses.

This embodiment is a method for treating steelmaking slag for promoting aging of steelmaking slag (hereinafter referred to as "this treatment method"). In this treatment method, an aging treatment step of promoting aging of slag is performed while stirring the mixture (mixture) M of water and slag M and crushing the slag in the mixture M in the crushing container 21. In the aging treatment step, the iron ball (spherical body) B is stirred together with the mixture M in the crushing container 21 and the iron ball B is made to collide with the slag to crush the slag. Further, in the aging treatment step, steam is supplied below the liquid surface of the mixture M in the crushing container 21 during the stirring of the mixture M and the crushing of the slag, and the temperature of the mixture M is the hydration reaction of the free lime. The temperature is adjusted to a suitable temperature range (60 ° C to 80 ° C).

In the present embodiment, even when the slag in the mixture M contains powder, the water immediately contacts the crushed surface of the slag. Therefore, the hydration reaction is started on the crushed surface of the slag, and the aging is effectively promoted. Hereinafter, the present embodiment will be described in more detail.

[Configuration of slag processing system]
First, a steelmaking slag treatment system (hereinafter referred to as “slag treatment system”) 10 used in this treatment method will be described. As shown in FIG. 1, the slag processing system 10 includes a crushing device 20, a slag charging device 27, a separation tank 30, a cooling device 35, a steam supply device 40, a carbon dioxide gas supply device 45, a dry ice supply unit 48, and a slurry. It is equipped with a receiving tank 50.

The crushing device 20 is a device that mechanically grinds slag in a wet manner. In the present embodiment, the crushing device 20 is a wet tower mill and is also a ball mill that crushes using an iron ball B. The crushing device 20 includes a crushing container 21 in which a mixture M of water and slag is agitated, a stirring blade 22 arranged in the crushing container 21, and a drive mechanism 23 for rotating the stirring blade 22. The crushing device 20 stirs the mixture M and crushes the slag in the mixture M in the crushing container 21.

Specifically, the crushing container 21 is a cylindrical vertical container. The crushing container 21 is filled with a large number of iron balls B. Further, the drive mechanism 23 has a rotating shaft 24 in which the stirring blade 22 is integrated, and a motor 25 for rotating the rotating shaft 24. The rotation shaft 24 extends in the vertical direction. Further, the stirring blade 22 is formed in a spiral shape centered on, for example, the rotating shaft 24. The stirring blade 22 is provided from the bottom to the top of the crushing container 21.

In the crushing device 20, the mixture M is stirred by rotating the stirring blade 22 by the motor 25. At that time, the iron ball B moves up and down by the stirring blade 22, and the iron ball B collides with the slag to crush the slag. As the iron ball B, for example, one having a diameter of 20 mm can be used. In this case, the slag in the mixture M after the aging treatment is slag powder having 60% by mass or more of particles having a size of 10 μm or less. In the crushing apparatus 20, the crushing particle size and the processing amount can be changed by changing the size and filling amount of the iron ball B.

The slag charging device 27 is a device for charging slag into the crushing container 21. The slag charging device 27 includes a raw material charging port 28 having an outlet opening on the water surface of the crushing container 21, and a raw material transporting unit 29 for transporting the slag and dropping the slag toward the raw material charging port 28. The raw material input port 28 is a hopper having a large opening at the entrance, and is attached to the upper part of the crushing device 20. Further, the raw material transport unit 29 is, for example, a transport vehicle. The raw material transport unit 29 transports the slag from a position where the slag is loaded into the transport vehicle by a heavy machine such as a bulldozer to a position above the raw material input port 28, and loads the slag.

The separation tank 30 is an elutriation tank that separates slags having different particle sizes by utilizing the fact that the sedimentation speed differs depending on the particle size of the slags. The upper part of the separation tank 30 is connected to the upper part of the crushing container 21. In the aging treatment step, the water level of the separation tank 30 becomes equal to the water level of the crushing container 21, and the mixture M is discharged from the crushing container 21 to the separation tank 30. Further, in the separation tank 30, a stirrer 34 is provided at a position closer to the crushing container 21. The stirrer 34 stirs the upper layer of the mixture M stored in the separation tank 30.

Further, the lower portion of the separation tank 30 is formed in a tapered shape, and the inlet of the liquid pipe 31 is connected to the lower end portion of the separation tank 30. The outlet of the liquid pipe 31 is connected to the lower part of the crushing container 21. A pump 39 is provided in the liquid pipe 31. As a result, the coarse-grained slag (slag having a relatively large particle size) that settles to the bottom in the separation tank 30 is returned to the crushing container 21 together with the water through the liquid pipe 31. Therefore, the slag that is insufficiently crushed is finely crushed in the crushing container 21.

The cooling device 35 is a device for cooling the liquid flowing through the liquid pipe 31. The cooling device 35 includes a cooling water discharge unit 36 that discharges cooling water, a cooling pipe 33 extending from the cooling water discharge unit 36, and a heat exchanger 32 connected in the middle of the liquid pipe 31. In the heat exchanger 32, heat exchange is performed between the first flow path forming a part of the liquid pipe 31 and the second flow path forming a part of the cooling pipe 33. As a result, in the liquid pipe 31, the water containing the slag is cooled by the cooling water of the cooling pipe 33. As the heat exchanger 32, for example, a spiral heat exchanger can be used.

The steam supply device 40 is a device that supplies steam having a high temperature of about 150 ° C. under the liquid level of the mixture M in the pulverizing container 21. The steam supply device 40 includes a steam discharge unit 41 that discharges high-temperature steam, and a gas pipe 42 that sends the steam released from the steam discharge unit 41 to the crushing container 21. The gas pipe 42 is connected to the crushing container 21 at a height at which water vapor is supplied below the liquid level. By the way, in the crushing container 21, the temperature of the mixture M rises due to crushing by the iron ball B without supplying high-temperature steam. For example, the temperature of the mixture M rises above 60 ° C. In the present embodiment, the steam supply device 40 supplies high-temperature steam when the temperature of the mixture M is further increased to promote aging. The steam supply device 40 uses steam so that the temperature of the mixture M is maintained in the range of 60 ° C. to 80 ° C., for example, based on the measured value of the temperature sensor that measures the temperature of the mixture M in the crushing container 21. Is supplied to the crushing container 21. In FIG. 1, the gas pipe 42 is connected to the lower part of the crushing container 21. Therefore, it is possible to prevent the water vapor from escaping onto the liquid surface at a high temperature, and it is possible to transfer more heat from the water vapor to the mixture M.

The carbon dioxide gas supply device 45 is a device that supplies carbon dioxide gas below the liquid level in the crushing container 21. The carbon dioxide gas supply device 45 includes a carbon dioxide gas discharge unit 46 that discharges carbon dioxide gas, and a gas pipe 47 that sends the carbon dioxide gas released from the carbon dioxide gas discharge unit 46 to the crushing container 21. The outlet of the gas pipe 42 is connected to the lower part of the crushing container 21. The carbon dioxide gas released from the carbon dioxide gas discharge unit 46 is supplied to the lower layer of the mixture M in the crushing container 21.

The dry ice supply unit 48 is a unit that supplies dry ice to the crushing container 21 when the temperature of the mixture M is lowered. The dry ice supply unit 48 supplies dry ice to the crushing container 21 via the gas pipe 47 of the carbon dioxide gas supply device 45. For example, the dry ice supply unit 48 supplies dry ice to the downstream of the gas pipe 47 through the pipe 49. Then, the dry ice supplied to the gas pipe 47 is supplied together with carbon dioxide gas below the liquid level (lower layer of the mixture M) in the crushing container 21. The dry ice may be added from above the liquid surface in the crushing container 21, but the carbon dioxide dissolution efficiency is better when the dry ice is supplied below the liquid surface.

The slurry receiving tank 50 is a container (tank) that receives and stores the slurry-like mixture M discharged from the upper part of the separation tank 30. A dust collecting net 52 is provided at the inlet of the slurry receiving tank 50. Further, the slurry receiving tank 50 is equipped with a stirrer 51 for stirring the stored mixture M.

[First treatment method for steelmaking slag]
Among the present processing methods using the slag processing system 10, the first processing method for operating the steam supply device 40 will be described. In the first treatment method, the carbon dioxide gas supply device 45 is not operated. Further, the stirring machine 34 is operated in the separation tank 30, and the stirring machine 51 is operated in the slurry receiving tank 50. The slag charged into the crushing container 21 is a high basicity slag (for example, stainless steel slag having a basicity of 1.6 or more), and this slag is pulverized in the cooling process from the molten state. ing. The average particle size of this slag is, for example, 10 μm to 44 μm.

First, the preparation process is performed. In the preparatory step, water is filled in the crushing container 21 provided with a large number of iron balls B. The crushing container 21 is filled with water until the water level reaches the upper part.

In this state, the aging process is performed. In the aging process, the slag is charged into the crushing container 21 by the slag charging device 27 in a state where the drive mechanism 23 is operated to rotate the stirring blade 22. In the crushing container 21, the mixture M in which water and slag are mixed is stirred, and the slag is finely pulverized by the iron ball B. The mixture M becomes a slurry. In the crushing container 21, the slag and water come into contact with each other to carry out the hydration reaction represented by the formula 1.
Equation 1: CaO + H ₂ O → Ca (OH) ₂

Further, in the aging treatment step, the temperature of the mixture M in the crushing container 21 is raised by operating the steam supply device 40 to supply the high-temperature steam to the crushing container 21. The temperature of the mixture M is maintained in the range of 60 ° C. to 80 ° C. under the control of the steam supply device 40.

Further, in the crushing container 21, the stirring blade 22 generates a spiral flow from the lower layer to the upper layer. Then, the upper layer mixture M overflows from the crushing container 21 and is discharged, and flows into the separation tank 30. Along with the discharge of the mixture M, slag is put into the crushing container 21 and water is supplied. In the crushing apparatus 20, continuous processing is performed.

In the separation tank 30, the mixture M overflows and is discharged as a series of treatments in the aging treatment step. In the separation tank 30, since the coarse-grained slag is settled, the mixture M from which the coarse-grained slag has been removed is discharged. Then, the discharged mixture M flows into the slurry receiving tank 50. On the other hand, the coarse-grained slag settles to the bottom of the separation tank 30 and flows into the liquid pipe 31. The coarse-grained slag is returned to the crushing container 21 through the liquid pipe 31. Then, in the crushing container 21, it is finely crushed in the process of moving from the lower layer to the upper layer. In the first processing method, the cooling device 35 is not operated.

In the slurry receiving tank 50, the mixture M after the aging treatment step is stored. The slag powder of the mixture M after the aging treatment step contains 60% by mass or more of particles having a particle size of 10 μm or less as measured by a laser diffraction / scattering method. After that, the mixture M in the slurry receiving tank 50 is discharged to the outside, and a commercialization step of manufacturing a slag product from the discharged mixture M is performed. In the commercialization process, the mixture M is blended and processed according to the request to obtain slag products such as roadbed materials for roads, aggregates for marine blocks, and cement milk materials.

[Effects of the first processing method, etc.]
In the first treatment method, the stainless slag charged into the crushing container 21 is in a pulverized state due to disintegration, but since the mixture M is stirred and the slag is crushed at the same time in the crushing container 21, the slag is crushed. Moisture immediately contacts the surface and the hydration reaction begins on the crushed surface of the slag. On the crushed surface, the activity of the reaction is high and the hydration reaction proceeds quickly. Further, since the slag is crushed, the number of particles is dramatically increased and the specific surface area of each particle is increased, so that the rate of the hydration reaction in the entire slag in the mixture M is also dramatically increased. Further, since the mixture M is stirred in the crushing container 21, it is discharged from the crushing container 21 in a uniform reaction state. Therefore, according to the first treatment method, the expansion rate of the slag falls below a predetermined value in a short time, and the aging treatment can be completed.

Further, in the first treatment method, the temperature of the mixture M is raised by supplying high-temperature steam. Here, the hydration reaction is promoted as the water temperature is higher. Therefore, the aging process can be completed in a shorter time. Further, in the crushing container 21, the stirring energy is converted into heat energy by the collision of the iron balls B, and the temperature rises to some extent without heating. Therefore, the energy consumption of the steam supply device 40 can be reduced.

Further, in the first treatment method, aging treatment can be performed on an industrial scale by using equipment such as a tower mill and a ball mill. Further, since the mixture M overflowing in the crushing container 21 or the separation tank 30 is discharged, it is possible to continuously perform a large amount of slag aging treatment. Therefore, the highly basic stainless slag, which has been used only for landfill disposal, can be effectively used for other purposes (civil engineering materials, etc.), and the amount of landfill disposal can be reduced.

Further, the first treatment method can be applied to steelmaking slag other than stainless steel slag, and even in that case, the aging treatment can be completed in a shorter time than before.

[Second treatment method for steelmaking slag]
Subsequently, a second treatment method for the steelmaking slag that operates the carbon dioxide gas supply device 45 will be described. In the second treatment method, a carbonation treatment that promotes the carbonation reaction is performed. In the second processing method, the steam supply device 40 is not operated. Further, the stirring machine 34 is operated in the separation tank 30, and the stirring machine 51 is operated in the slurry receiving tank 50. In the following, explanations will be given focusing on the points different from the first processing method.

In the second treatment method, stainless slag is charged into the crushing container 21. In the aging treatment step, the mixture M in which water and slag are mixed is stirred in the crushing container 21, and the slag is crushed by the iron balls B. Then, carbon dioxide gas is supplied to the crushing container 21 by the carbon dioxide gas supply device 45 during the stirring of the mixture M and the crushing of the slag. In the mixture M in the crushing container 21, carbon dioxide gas is dissolved and the carbonation reaction represented by the formula 2 is carried out.
Equation 2: CaO + CO ₃ → CaCO ₃

In the carbonation reaction, the solubility of carbon dioxide in water is the rate-determining factor. In addition, the solubility of carbon dioxide in water decreases as the water temperature rises. Therefore, the carbonation reaction is promoted as the water temperature is lower. Therefore, in the second treatment method, the cooling device 35 is operated to cool the water (containing coarse slag) returning to the crushing container 21 through the liquid pipe 31. The cooling device 35 controls the supply amount and temperature of the cooling water so that the temperature of the mixture M in the pulverizing container 21 is in the range of 30 ° C. to 40 ° C.

Here, in the crushing container 21, heat generation in the carbonation reaction and heat generation due to the collision of the iron balls B are generated. Therefore, even if the cooling device 35 is operated, the mixture M in the crushing container 21 may exceed 40 ° C. In such a case, the dry ice supply unit 48 puts the dry ice into the crushing container 21. As a result, the temperature of the mixture M in the crushing container 21 is lowered. Further, since carbon dioxide gas is generated from the dry ice, the carbonation reaction in the whole mixture M is further promoted.

[Effects of the second processing method, etc.]
In the second treatment method, the stainless slag charged into the crushing container 21 is in a pulverized state due to disintegration, but the mixture M is stirred and the slag is crushed at the same time in the crushing container 21, so that the slag is crushed. The carbonic acid gas immediately comes into contact with the surface, and the carbonation reaction is started on the crushed surface of the slag. On the crushed surface, the activity of the reaction is high and the carbonation reaction proceeds quickly. Therefore, according to the second treatment method, the carbonation treatment can be completed in a short time, and the elution of highly alkaline water can be suppressed at the place where the slag is used.

[Modified example of the embodiment]
In this modification, as shown in FIG. 2, the slag processing system 10 includes a first crushing device 20 and a second crushing device 120 provided after the first crushing device 20. Similar to the first crushing device 20, the second crushing device 120 includes a crushing container 121, a stirring blade arranged in the crushing container 121, and a drive mechanism for rotating the stirring blade. Further, the outlet of the gas pipe 42 of the steam supply device 40 is connected to the crushing container 21 of the first crushing device 20, and the outlet of the gas pipe 47 of the carbon dioxide gas supply device 45 is the crushing container of the second crushing device 120. It is connected to 121. The dry ice supply unit 48 of the above-described embodiment may be provided in the crushing container 121 of the second crushing device 120.

A separation tank 30 having the same configuration as that of the above-described embodiment is connected to the upper part of the crushing container 21 of the first crushing device 20. A connection pipe 100 connected to the lower part of the crushing container 121 of the second crushing device 120 is connected to the upper part of the separation tank 30. The mixture M flowing out of the crushing container 21 of the first crushing device 20 flows into the crushing container 121 of the second crushing device 120 via the separation tank 30. Further, the heat exchanger 32 of the cooling device 35 is connected to the connection pipe 100. The mixture M cooled by the heat exchanger 32 flows into the second pulverizer 120. Further, a pipe connected to a slurry receiving tank (not shown) is connected to the upper part of the crushing container 121 of the second crushing device 120.

In the aging treatment step, while the mixture M is stirred and the slag is crushed in the crushing container 21 (first container) of the first crushing device 20, the steam is collected by the steam supply device 40 of the mixture M in the crushing container 21. It is supplied below the liquid level. Further, in the crushing container (second container) 121 of the second crushing device 120, the carbon dioxide gas is generated by the carbon dioxide gas supply device 45 while the mixture M is being stirred and the slag is crushed. It is supplied below the liquid level.

In this modification, after the aging treatment is performed in the high temperature water of the previous stage, the carbonation treatment is performed in the low temperature water of the subsequent stage. Here, carbonic acid oxide is more stable in nature than hydrate, and the particles become harder. Therefore, when it is reused as a material for roadbed materials and the like, it is preferable to carry out a carbonation reaction in the subsequent stage.

The slag treatment system 10 may be configured so that the carbonation treatment is performed in the low temperature water of the previous stage and then the aging treatment is performed in the high temperature water of the subsequent stage. In this case, the outlet of the gas pipe 42 of the steam supply device 40 is connected to the crushing container 121 of the second crushing device 120, and the outlet of the gas pipe 47 of the carbon dioxide gas supply device 45 is for crushing the first crushing device 20. It is connected to the container 21. Further, the heat exchanger 32 is connected to the liquid pipe 31 in the same manner as in the above-described embodiment. When the dry ice supply unit 48 is provided, it is provided for the crushing container 21 of the first crushing device 20 in the same manner as in the above-described embodiment.

[Other embodiments]
In the present embodiment, as the wet crusher device, another type such as a horizontal mill or a centrifugal mill may be used for the crusher 20.

In this embodiment, the separation tank 30 may be omitted. In this case, a filter for removing coarse-grained slag may be provided between the crushing device 20 and the slurry receiving tank 50.

In the present embodiment, the slag in the mixture after the aging treatment step may have a particle size distribution different from that of the above-described embodiment.

In the present embodiment, both the cooling device 35 and the dry ice supply unit 48 are provided in order to lower the temperature of the crushing container 21 on which the carbonation treatment is performed, but one of them may be omitted.

The present invention can be applied to a slag processing method or the like that promotes aging of steelmaking slag.

10 Steelmaking slag processing system 20 Crushing device 21 Crushing container (container)
22 Stirring blade 27 Slag input device 30 Separation tank 32 Heat exchanger 35 Cooling device 40 Steam supply device 45 Carbon dioxide gas supply device

Claims (11)

It is a method of processing steelmaking slag.
A method for treating steelmaking slag, which comprises an aging treatment step of promoting aging of the slag while stirring a mixture of water and slag and crushing the slag in a container. The method for treating steelmaking slag according to claim 1, wherein in the aging treatment step, water vapor is supplied below the liquid surface of the mixture during the stirring of the mixture and the crushing of the slag. The method for treating steelmaking slag according to claim 1, wherein in the aging treatment step, carbon dioxide gas is supplied below the liquid surface of the mixture during the stirring of the mixture and the crushing of the slag. The method for treating steelmaking slag according to any one of claims 1 to 3, wherein the slag in the mixture after the aging treatment step contains 60% by mass or more of particles having a particle size of 10 μm or less. In the aging treatment step, the slag is crushed by stirring the sphere with the mixture in the container and causing the slag to collide with the slag, according to any one of claims 1 to 4. The method for treating steelmaking slag described. The method for treating steelmaking slag according to any one of claims 1 to 5, wherein in the aging treatment step, the mixture is discharged from the container to the separation tank, and the slag that has settled to the bottom in the separation tank is returned to the container. .. In the aging treatment step, the mixture is discharged from the container to the separation tank, and the slag that settles to the bottom in the separation tank is returned to the container together with water through a pipe.
The method for treating steelmaking slag according to claim 3, wherein the pipe cools the water containing the slag. The method for treating steelmaking slag according to claim 3 or 7, wherein dry ice is supplied to the container when the temperature of the mixture in the container is lowered. Using the container as the first container,
In the aging treatment step, either steam or carbon dioxide gas is supplied below the liquid surface of the mixture during the stirring of the mixture and the crushing of the slag in the first container, and the mixture is discharged from the first container. The steelmaking slag according to claim 1, wherein in the second container into which the mixture flows, the other of steam or carbon dioxide gas is supplied below the liquid surface of the mixture during the stirring of the mixture and the pulverization of the slag. Processing method. A method for producing a slag product, which comprises a commercialization step of producing a slag product from the mixture after the aging treatment step in the treatment method according to any one of claims 1 to 9. It is a steelmaking slag processing system.
A steelmaking slag processing system comprising a container in which a mixture of water and slag is agitated, and a crushing device for stirring the mixture and crushing the slag in the mixture in the container.

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