WO2022270480A1

WO2022270480A1 - Granular solidified slag manufacturing method and manufacturing facility

Info

Publication number: WO2022270480A1
Application number: PCT/JP2022/024604
Authority: WO
Inventors: 恵太田; 伸行紫垣; 久宏松永
Original assignee: Ｊｆｅスチール株式会社
Priority date: 2021-06-24
Filing date: 2022-06-20
Publication date: 2022-12-29
Also published as: TW202317500A

Abstract

Provided is a granular solidified slag manufacturing method with which a granular solidified slag having a grain size distribution which falls within a standard grain size range of steel slag for roads can be easily manufactured. This granular solidified slag manufacturing method comprises: a step for supplying a granular solid material S1 and a molten slag S2 into a mold; a step for solidifying the molten slag S2 together with the granular solid material S1 in the mold 10 to obtain a plate-like solidified slag S comprising a solidified region formed of the molten slag S2 that has solidified and the granular solid material S1 and having a thickness of 30-50 mm; a step for removing the plate-like solidified slag S from the mold 10; and a step for loading the plate-like solidified slag S into a rotating cylindrical container of a rotating device 40 which comprises the cylindrical container, and then rotating the cylindrical container so as to crush the plate-like solidified slag S, thereby obtaining a granular solidified slag Sg.

Description

Granular solidified slag manufacturing method and manufacturing equipment

The present invention relates to a method and equipment for producing granular solidified slag, which crushes solidified slag obtained by solidifying molten slag to obtain granular solidified slag.

Regarding molten slag, when 1 ton of steel is produced, approximately 300 kg of blast furnace slag and approximately 50 kg of steelmaking slag are generated. For this reason, technological developments have been made to effectively utilize these iron and steel slags that are generated in large amounts. In particular, steelmaking slag is mostly used as steel slag for roads (JIS A 5015-2018). The manufacturing process includes pouring molten slag with a partially precipitated solid phase into a cooling yard with a thickness of 100 mm or more, crushing the solidified slag obtained by solidification, and further adjusting the particle size. A steam aging treatment is then performed at 100° C. for several days to hydrate the free-CaO contained in the crushed and granulated solidified slag. The granular solidified slag thus obtained is shipped as steel slag for roads.

In the current process described above, the molten slag is solidified with a thickness of 100 mm or more, so it takes time to cool the molten slag.

In order to solve this problem, for example, Patent Document 1 devises a process of solidifying molten blast furnace slag in an iron mold to a thickness of 20 to 40 mm to obtain plate-shaped solidified slag. According to this method, the molten slag can be efficiently cooled and solidified in a short period of time.

JP-A-2015-40638

In the method of Patent Document 1, the obtained plate-shaped solidified slag with a thickness of 20 to 40 mm is crushed, and the granular solidified slag in the particle size range of the standard coarse aggregate for concrete (the maximum slag particle diameter is about 20 mm) is obtained. We aim to produce well. In Patent Document 1, since the plate-shaped solidified slag consists only of solidified regions formed by solidifying molten slag, it has high compressive strength even at high temperatures and is difficult to be crushed. Therefore, even if an attempt is made to crush plate-shaped solidified slag while it is still at high temperature by a rotating device such as a rotary kiln, the crushing force of such a rotating device is small, so that it can hardly be crushed. Therefore, it is assumed that after the plate-shaped solidified slag is cooled to room temperature, it is crushed by a general compression crushing type crusher such as a jaw crusher and/or an impact crusher. In that case, the maximum particle size of the slag after crushing is determined to some extent by the thickness of the plate-shaped solidified slag. Granular solidified slag having a maximum particle diameter of about 20 mm can be obtained with a high yield.

However, with the method of Patent Document 1, it is not possible to obtain steel slag for roads in the standard particle size range (slag particle diameter is about 40 mm at maximum, standard "CS-40" described later) with a high yield. When the plate-shaped solidified slag has a thickness of 30 mm or less, most of the granular solidified slag after crushing has a particle diameter of 20 mm or less, and therefore does not fall within the specification range of CS-40. If the plate-shaped solidified slag has a thickness of about 40 mm, it is possible to obtain a particle size distribution close to that of CS-40. There is concern that the heat load on the For this reason, in the conventionally devised processes including Patent Document 1, it was not possible to easily produce granular solidified slag having a particle size distribution that falls within the particle size range of the steel slag standard for roads.

Therefore, in view of the above problems, the present invention provides a method and equipment for producing granular solidified slag that can easily produce granular solidified slag having a particle size distribution that falls within the particle size range of steel slag standards for roads. With the goal.

As a result of examination by the present inventors,
(A) feeding particulate solids and molten slag into a mold and solidifying the molten slag together with the particulate solids in the mold;
(B) At that time, the solidified thickness shall be 30 mm or more and 50 mm or less; and rotating the cylindrical container to crush the plate-shaped solidified slag;
It was found that by adopting the configuration of , it is possible to easily produce granular solidified slag that falls within the standard particle size range for steel slag for roads. By solidifying the molten slag together with the granular solids and introducing cracks into the plate-shaped solidified slag, the hot crushability of the plate-shaped solidified slag is enhanced, and a general compression crushing type crusher This is probably because the plate-shaped solidified slag can be appropriately crushed by using a rotating device with a smaller crushing force than the above.

The gist and configuration of the present invention completed based on the above findings are as follows.
[1] A step of supplying particulate solids and molten slag into a mold;
a step of solidifying the molten slag together with the granular solids in the mold to obtain a plate-like solidified slag having a thickness of 30 mm or more and 50 mm or less, which consists of a solidified region formed by solidifying the molten slag and the granular solids;
removing the plate-shaped solidified slag from the mold;
A step of charging the plate-shaped solidified slag into the cylindrical container of a rotating device having a rotating cylindrical container, rotating the cylindrical container to crush the plate-shaped solidified slag, and obtaining granular solidified slag. When,
A method for producing granular solidified slag.

[2] The above-mentioned [1], wherein the granular solid material includes one or more selected from granular solid slag, granular solid material having one or both of hydrate and carbonate formed on the surface, and granular solid iron. ] The method for producing granular solidified slag according to .

[3] The granular solid slag and the granular solid material have a particle size range of 40 to 0 mm, and the nominal opening of a metal mesh sieve specified in JIS Z 8801-1: 2019 (ISO 3310-1: 2016) , 53 mm sieve passage rate is 100% by mass, 37.5 mm sieve passage rate is 95 to 100% by mass, 19 mm sieve passage rate is 50 to 80% by mass, 4.75 mm sieve passage rate is 15 to 40% by mass. , The method for producing granular solidified slag according to the above [2], wherein the sieve passage rate of 2.36 mm has a particle size distribution of 5 to 25% by mass.

[4] The method for producing granular solidified slag according to [2] above, wherein the granular solid iron has a particle size range of 10 mm or more and 50 mm or less.

[5] Any one of [1] to [4] above, wherein the mass of the particulate solid is 10% by mass or more and 40% by mass or less with respect to the total mass of the particulate solid and the molten slag. A method for producing the described granular solidified slag.

[6] Any one of [1] to [5] above, wherein the plate-shaped solidified slag has an average temperature of 600° C. or higher and 1250° C. or lower when charged into the cylindrical container of the rotating device. The method for producing granular solidified slag according to .

[7] The rotating device crushes the plate-shaped solidified slag to a particle size of 53 mm or less, and at that time, the 19 mm sieve passage rate of the granular solidified slag is 50% by mass or more and 80% by mass or less. ] A method for producing a granular solidified slag according to any one of [6].

[8] Among the granular solidified slag, the particle shape determination using coarse slag adjusted to conform to the particle size distribution of crushed stone 2005 specified in JIS A 5005; The method for producing granular solidified slag according to any one of [1] to [7] above.

[9] Among the granular solidified slag, the particle shape determination using fine-grained slag adjusted to conform to the particle size distribution of crushed sand specified in JIS A 5005; 2020 is 52.0% or more. A method for producing granular solidified slag according to any one of [1] to [8].

[10] A mold, a particulate solid supply device that supplies particulate solids into the mold, and a molten slag supply device that supplies molten slag into the mold, wherein the molten slag is supplied in the mold. a slag solidification facility for solidifying together with the granular solid matter to obtain a plate-shaped solidified slag having a thickness of 30 mm or more and 50 mm or less composed of the solidified region formed by solidifying the molten slag and the granular solid matter;
a rotating device comprising a rotating cylindrical container for crushing the plate-shaped solidified slag charged into the cylindrical container by rotating the cylindrical container to obtain granular solidified slag;
Production equipment for granular solidified slag.

According to the method and equipment for producing granular solidified slag of the present invention, it is possible to easily produce granular solidified slag having a particle size distribution that falls within the particle size range of steel slag standards for roads.

1 illustrates a granular solidified slag production facility 100 according to an embodiment of the present invention; FIG.

(Manufacturing method and manufacturing equipment for granular solidified slag)
FIG. 1 is a diagram showing a granular solidified slag manufacturing facility 100 according to an embodiment of the present invention as an example of a facility capable of implementing a granular solidified slag manufacturing method according to an embodiment of the present invention. Referring to FIG. 1, a granular solidified slag production facility 100 includes a slag solidification facility having a mold 10, a granular solid supply device 20, and a molten slag supply device 30, and a rotating device 40 as a slag crushing device. have.

A method for producing granular solidified slag according to one embodiment of the present invention comprises:
- Step (I): a step of supplying the particulate solid S1 and the molten slag S2 into the mold 10;
- Step (II): The molten slag S2 is solidified together with the granular solids S1 in the mold 10, and the solidified region formed by solidifying the molten slag S2 and the granular solids S1 have a thickness of 30 mm or more and 50 mm. a step of obtaining a plate-like solidified slag S below;
- Step (III): a step of removing the plate-shaped solidified slag S from the mold 10;
- Step (IV): The plate-shaped solidified slag S is charged into the cylindrical container of a rotating device 40 having a rotating cylindrical container, and the cylindrical container is rotated to crush the plate-shaped solidified slag S. to obtain granular solidified slag Sg;
have

[template]
The mold 10 has recesses that accommodate the particulate solid S1 and the molten slag S2. The shape of the recess is not particularly limited as long as the plate-shaped solidified slag S can be taken out from the mold 10 by inverting the mold 10. can be mentioned. The dimensions of the recess may be set so that the desired dimensions of the plate-like solidified slag S are obtained. When the shape of the concave portion is a rectangular parallelepiped, the vertical and horizontal lengths can be within the range of 600 to 3000 mm, for example. The height of the recess may be set so as to obtain a desired dimension of the plate-shaped solidified slag S, and can be, for example, within the range of 40 to 100 mm. Further, as shown in FIG. 1, the mold 10 is conveyed on the line and sequentially receives the granular solid S1 from the granular solid supply device 20, and then the molten slag S2 from the molten slag supply device 30. receive.

[Particulate solid supply device]
The granular solid material supply device 20 has a hopper 20A that accommodates the granular solid material S1 and cuts out a predetermined amount, and a gutter 20B that guides the granular solid material S1 cut out by the hopper 20A into the mold 10. Then, a granular solid S1 is supplied into the mold 10. As shown in FIG. A particulate solid feeder 20 is located above the line along which the molds 10 are conveyed.

[Molten slag supply device]
The molten slag supply device 30 includes a tilting ladle 30A that accommodates the molten slag S2 and pours out the molten slag S2 by tilting, and a gutter 30B for pouring the molten slag S2 poured out from the tilting ladle 30A into the mold 10. and to feed the molten slag S2 into the mold 10. The molten slag feeder 30 is located above the line along which the mold 10 is conveyed and is located downstream of the particulate solids feeder 20 in the line.

In the example shown in FIG. 1, the granular solid material S1 is first supplied into the mold 10 from the granular solid supply device 20, and then the molten slag S2 is supplied into the mold 10 from the molten slag supply device 30. When the molten slag S2 is supplied into the mold 10 before the solid particles S1 are fed into the mold 10, the temperature of the molten slag S2 drops, the viscosity rises, and the surface of the molten slag S2 begins to solidify. It becomes difficult to create a state in which the and are uniformly mixed. For this reason, as shown in FIG. Preferably, the molten slag S2 is fed into the mold 10 after the particulate solid S1 has been fed into the mold 10 . However, in the present invention, the order of supplying the solid particles S1 and the molten slag S2 into the mold 10 is not limited. The molten slag supply device 30 is arranged upstream of the granular solids supply device 20 in the line, and the molten slag S2 is first supplied into the mold 10 from the molten slag supply device 30, and then the granular solids S2 are supplied from the granular solids supply device 20. An object S1 can also be fed into the mold 10 . Further, both the gutter 20B and the gutter 30B are arranged above the mold 10, and the granular solid S1 is supplied from the granular solid supply device 20 into the mold 10, and the molten slag S2 is supplied from the molten slag supply device 30 during the same period. can also be fed into the mold 10. Further, in order to control the thickness of the slag, when the supply of the granular solid slag S1 and the molten slag S2 to the mold 10 is completed, rolling pressure may be applied from above the mold 10 with iron rolls.

[Step (I) and Step (II)]
In this embodiment, the granular solids S1 and the molten slag S2 are supplied into the mold 10 (step (I)), and the molten slag S2 is solidified together with the granular solids S1 in the mold 10 (step (II)). In this way, it is possible to obtain a plate-shaped solidified slag S composed of a solidified region formed by solidifying the molten slag S2 and the solid particles S1. That is, the "solidified zone" is the solidified portion of the molten slag, and the "platy solidified slag" is the slab in the mold, which consists of the solidified zone and particulate solids.

Here, in the present embodiment, the molten slag S2 is solidified together with the solid particles S1 in the mold 10, and the thickness of the obtained plate-like solidified slag S (herein also referred to as "solidified thickness") is set to 30 mm. It is important to make it 50 mm or less. In the mold 10, solidification of the molten slag S2 proceeds in a state where the gaps between the solid particles S1 are filled with the molten slag S2, thereby introducing cracks into the solidified region.

Since the temperature difference between the granular solid S1 near room temperature and the molten slag S2 at 1200° C. or higher is extremely large, when the molten slag S2 is solidified together with the granular solid S1, a large thermal stress is generated inside the solidified region. promotes crack generation. In addition, since the solidified region thermally shrinks due to cooling, whereas the granular solid S1 thermally expands due to heating, this volume change also promotes crack generation. Furthermore, since mismatching occurs in the crystal interface at the boundary between the solidified region and the granular solid S1, cracks tend to develop at the boundary. Due to the synergistic effect described above, the plate-shaped solidified slag S in this embodiment is superior in hot crushability to solidified slag obtained by solidifying only molten slag. Therefore, the plate-shaped solidified slag S can be easily crushed by the rotating device 40 .

On top of that, by setting the thickness of the plate-shaped solidified slag S to 30 mm or more and 50 mm or less, the granular solidified slag Sg obtained by subsequent crushing can have a particle size suitable for steel slag for roads. The particle size distribution of steel slag for roads is specified in JIS A 5015-2018, and CS-40 is used in particular. CS-40 has a particle size range of 40 to 0 mm, a nominal opening of a metal mesh sieve specified in JIS Z 8801-1: 2019 (ISO 3310-1: 2016), and a 53 mm sieve passage rate of 100 mass. %, 37.5 mm sieve passage rate is 95 to 100% by mass, 19 mm sieve passage rate is 50 to 80% by mass, 4.75 mm sieve passage rate is 15 to 40% by mass, 2.36 mm sieve passage rate is It has a particle size distribution of 5-25% by weight. In order to obtain the CS-40 grain size with a high yield, it is important to control the thickness of the plate-like solidified slag S to about 40 mm. If the thickness of the plate-shaped solidified slag S is less than 30 mm, the maximum particle size of the obtained granular solidified slag is less than 30 mm, and the particle size becomes finer, which reduces the yield of CS-40. On the other hand, if the thickness of the plate-like solidified slag S exceeds 50 mm, the particle size of the crushed slag becomes large, and the yield of CS-40 decreases.

The molten slag S2 contains a liquid phase of 1200°C or higher, and may be iron and steel slag generated as a by-product in the steelmaking process, and may contain one or both of blast furnace slag and steelmaking slag.

The granular solid S1 preferably contains one or more selected from granular solid slag, granular solid material on the surface of which one or both of hydrates and carbonates are formed, and granular solid iron. First, a granular solid slag can be used as the granular solid S1. For example, by using granular solid slag generated in the same process as the molten slag S2, there is no foreign matter contamination, so the quality of the obtained granular solidified slag Sg can be easily stabilized. Alternatively, other steelmaking slag or blast furnace slag may be used. In addition, when one or both of hydrates and carbonates are formed on the surface of the granular solid slag, the decomposition reaction of the hydrates or the decomposition reaction of the carbonates causes cracks in the plate-shaped solidified slag S. Production can be promoted, and the crushing load can be further reduced.

Secondly, as the granular solid S1, a granular solid having one or both of a hydrate and a carbonate formed on its surface can be used. Examples of such substances include waste concrete. When the hydrates or carbonates formed on the surface of the waste concrete come into contact with the high-temperature molten slag, the decomposition reaction of the hydrates or the decomposition reaction of the carbonates promotes the formation of cracks in the plate-shaped solidified slag S. It is possible to further reduce the crushing load. In general, the decomposition of hydrates occurs at 100 to 300 ° C., and the decomposition of carbonates occurs at 600 ° C. or higher, so these decomposition reactions can easily occur when hot molten slag contacts. . Note that the waste concrete is construction waste material, such as concrete, which is a specific construction material that is obligated to be sorted, dismantled and recycled according to the Construction Recycling Law. For these waste concrete, the used concrete is crushed and recycled material for concrete conforming to Annex A of JIS A 5023: 2018 recycled aggregate concrete L, JIS A 5023: 2018 recycled aggregate concrete M attached Recycled aggregate M for concrete conforming to Book A, and recycled crusher run and recycled sand described in pavement recycling handbook (Japan Road Association, 2010) are included.

Thirdly, granular solid iron can be used as the granular solid S1. By using, for example, iron balls as the solid iron granules, the temperature difference with the molten slag is increased compared to other solid granules, so the effect of further promoting the formation of cracks can be expected. In addition, iron has better heat transfer than solid slag. An increase in volume and processing speed can be expected.

The granular solid slag and the granular solid material used as the granular solid material S1 preferably have a particle size distribution of CS-40. That is, the granular solid slag and the granular solid material have a particle size range of 40 to 0 mm, and the nominal opening of a metal mesh sieve specified in JIS Z 8801-1: 2019 (ISO 3310-1: 2016), 53 mm sieve passage rate is 100% by mass, 37.5 mm sieve passage rate is 95 to 100% by mass, 19 mm sieve passage rate is 50 to 80% by mass, 4.75 mm sieve passage rate is 15 to 40% by mass, It preferably has a particle size distribution with a sieve passage rate of 2.36 mm of 5 to 25% by weight. As a result, the granular solidified slag Sg after crushing can more reliably have a particle size suitable for steel slag for roads.

The granular solid iron used as the granular solid S1 preferably has a particle size range of 10 mm or more and 50 mm or less.

The granular solid S1 preferably contains one or more selected from the granular solid slag, the granular solid material, and the granular solid iron, and preferably contains two or more selected from these. In this case, as a combination to be selected, a combination of granular solid slag and granular solid iron is more preferable. Granular solid slag is the raw material for steel slag for roads, so even if it is solidified together with molten slag, there is almost no risk of contamination with impurities. This is because the advantage of being able to reduce the crushing energy of is also obtained. At this time, the preferred particle size range of the granular solid slag and granular solid iron is 10-50 mm. Since the regulation of the grain size of steel slag for roads is 53 mm, the sieve passage rate is 100%, so the solidified thickness is preferably 50 mm or less, and in order to take advantage of the cooling ability of granular solids, granular solid slag and granular solid iron By making the particle size range of 50 mm or less, a sufficient contact area with the molten slag can be secured.

Regarding the amount of the granular solid S1 and the molten slag S2 supplied into the mold 10, the mass of the granular solid S1 is 10% by mass or more and 40% by mass or less with respect to the total mass of the granular solid S1 and the molten slag S2. is preferred. This is because if the ratio is less than 10% by mass, sufficient crack propagation cannot be expected. On the other hand, if the ratio exceeds 40% by mass, the molten slag S2 does not spread sufficiently between the granular solids S1, and the granular solids S1 and molten slag S2 solidify in a substantially separated state. In addition, the processing amount of the molten slag S2 is reduced, and the processing speed of the molten slag becomes slow.

When the granular solids S1 are supplied into the mold 10 before the molten slag S2, the granular solids S1 should be arranged in the mold so that the granular solids S1 form one to three layers. is preferred. By limiting the number of stacked layers of the solid particles S1 to three or less, cracks introduced into the solidified region are easily propagated, and the plate-shaped solidified slag S is sufficiently excellent in hot crushability. From the viewpoint of promoting the propagation of cracks, it is most preferable to set the number of layers of the solid particles S1 to one.

When supplying the solid particles S1 and the molten slag S2 into the mold 10, it is preferable to uniformly disperse the solid particles S1 in the mold 10 so that the solid particles S1 and the molten slag S2 are in a mixed state. Further, when the number of layers of the granular solids S1 is set to one, the maximum particle size of the granular solids S1 supplied into the mold 10 is equal to or less than the thickness of the plate-shaped solidified slag S, and is larger than the thickness of the plate-shaped solidified slag S. It is preferable to make it 1/2 or more (more preferably 3/4 or more). If the maximum particle diameter (thickness) of the granular solid S1 is too small compared to the thickness of the plate-shaped solidified slag S, there will be a portion where the granular solid S1 and the molten slag S2 do not contact, and the plate-shaped solidified slag S will have This is because there are many regions in which cracks, which are starting points of destruction, do not occur, and it becomes difficult to crush the granular solidified slag Sg.

[Step (III) and Step (IV)]
In this embodiment, the plate-like solidified slag S is removed from the mold 10 following step (II) (step (III)). The method of removing the plate-shaped solidified slag S from the mold 10 is not particularly limited, but as shown in FIG. 1, by inverting the mold 10, the plate-shaped solidified slag S can be separated from the mold 10 and dropped.

In this embodiment, as shown in FIG. 1, subsequent to step (III), the plate-shaped solidified slag S is charged into the cylindrical container of a rotating device 40 having a rotating cylindrical container, and the cylindrical container is is rotated to crush the plate-shaped solidified slag S to obtain granular solidified slag Sg. The rotating device 40 is a device, such as a rotary kiln, having a rotating cylindrical container, and crushes the plate-shaped solidified slag S charged into the cylindrical container by rotating the cylindrical container. The rotating device 40 preferably has a structure in which projections are provided on the inner peripheral surface of the cylindrical container so that the plate-like solidified slag S is lifted and dropped. By crushing the plate-shaped solidified slag S with the rotating device 40, the crushed granular solidified slag Sg can have a particle size and particle shape (roundness) suitable for steel slag for roads.

Here, the plate-shaped solidified slag S preferably has an average temperature of 600°C or higher and 1250°C or lower when charged into the cylindrical container of the rotating device 40 . One of the features of this embodiment is that the plate-like solidified slag S can be hot crushed. That is, it is preferable that the average temperature of the plate-like solidified slag S during charging (also referred to as “charging temperature” in this specification) is 600° C. or higher.

The lower limit of the charging temperature is preferably determined according to the type of post-treatment for the granular solidified slag Sg obtained after crushing. When the post-process is a carbonation treatment, the charge temperature is preferably 600° C. or higher. Thereby, the average temperature of the granular solidified slag Sg during the carbonation treatment can be 400° C. or higher. When the post-process is a heat recovery treatment, the charge temperature is preferably 1100° C. or higher from the viewpoint of enhancing the heat recovery efficiency from the granular solidified slag Sg. Thereby, the average temperature of the granular solidified slag Sg during the heat recovery process can be 900° C. or higher.

By setting the charging temperature to 1250°C or lower, it is possible to stably produce granular solidified slag Sg having a particle size close to that of steel slag for roads. If the charging temperature is higher than 1250 ° C., a large amount of unsolidified portion remains in the plate-shaped solidified slag S, so that it adheres to the inner wall of the rotating device 40 and solidifies. It becomes difficult to produce a similar granular solidified slag Sg.

The rotation speed N (circumference/minute) of the cylindrical container is set so that the plate-shaped solidified slag sticks to the wall surface of the cylindrical container due to centrifugal force when the cylindrical container rotates, is lifted up to a certain height, and then falls. preferably. Let Nc (turns/minute) be the number of revolutions of the cylindrical container when the plate-shaped solidified slag sticks to the wall surface of the cylindrical container and rotates at the same number of revolutions as the cylindrical container. Also, the maximum number of rotations of the cylindrical container at which the plate-like solidified slag cannot be lifted is Nb (turns/minute). Although Nc and Nb differ depending on the filling amount of plate-shaped solidified slag, the diameter of the cylindrical container, etc., the number of revolutions N may be set within the range of Nb<N<Nc.

The treatment time in the rotating device is not particularly limited, and may be appropriately set so that the granular solidified slag Sg after crushing has a particle size suitable for steel slag for roads.

In this embodiment, through the steps (I) to (IV) described above, it is possible to easily produce granular solidified slag Sg having a particle size close to that of steel slag for roads.

Further, in the present embodiment, the rotating device 40 crushes the entire plate-shaped solidified slag S to a particle size of 53 mm or less, and at that time, the 19-mm sieve passage rate of the granular solidified slag Sg is 50% by mass or more and 80% by mass or less. is preferred. As a result, the granular solidified slag Sg can be prevented from being excessively crushed, and the granular solidified slag Sg can be stably produced within the particle size range of the steel slag standards for roads. It should be noted that "total crushing to a particle size of 53 mm or less" means that the entire amount of granular solidified slag Sg passes through a mesh sieve with a nominal size of 53 mm specified in JIS Z 8801-1: 2019 (ISO 3310-1: 2016). means to

In addition, in the present embodiment, of the obtained granular solidified slag Sg, the grain shape determination using coarse grain slag adjusted so as to conform to the grain size distribution of crushed stone 2005 specified in JIS A 5005; 0% or more is preferable. As a result, the particles of the granular solidified slag Sg have rounded shapes, making the granular solidified slag Sg suitable for steel slag for roads. Since it is preferable that the grain shape determination actual volume ratio of coarse grains is as high as possible, the upper limit is not particularly limited.

Further, in the present embodiment, of the obtained granular solidified slag Sg, fine grain slag adjusted so as to conform to the grain size distribution of crushed sand specified in JIS A 5005; It is preferably 0% or more. As a result, the particles of the granular solidified slag Sg have rounded shapes, making the granular solidified slag Sg suitable for steel slag for roads. Since the grain shape determination actual volume ratio of fine grains is preferably as high as possible, the upper limit is not particularly limited.

The "grain shape determination actual volume rate" referred to here refers to "6.6 grain shape determination actual volume rate for crushed stone and crushed sand for concrete" specified in JIS A 5005:2020. The particle shape determination actual volume ratio of the coarse-grained slag is obtained as follows. First, the granular solidified slag is thoroughly dried to an absolute dry state, passed through a sieve with a nominal size of 20 mm, and 24 kg of those remaining on a sieve with a nominal size of 10 mm are passed through a sieve with a nominal size of 5 mm. 16 kg of those remaining in the sample are sieved, mixed well, and the unit volume mass is obtained by the method specified in JIS A 1104: 2019 (ISO 6782: 1982), divided by the absolute dry density of the sample. , the grain shape determination actual volume ratio. The particle shape determination actual volume ratio of the fine slag is obtained as follows. While thoroughly washing the granular solidified slag with water, it passes through a sieve with a nominal size of 2.5 mm, and the slag that remains on a sieve with a nominal size of 1.2 mm is sieved, then dried well until it becomes absolutely dry, JIS A 1104: 2019 (ISO 6782: 1982) to determine the unit volume mass and divide it by the absolute dry density of the sample to obtain the particle shape determination solid volume rate.

[Post-process]
The granular solidified slag Sg can be shipped as steel slag for roads after cooling to room temperature. However, in the present embodiment, granular solidified slag Sg can be obtained in a high temperature state. Therefore, the granular solidified slag Sg may be shipped after being post-treated. Examples of the post-treatment include heat recovery treatment, steam recovery treatment, carbonation treatment, steam aging treatment, and classification treatment.

In the heat recovery process, the obtained high-temperature granular solidified slag Sg is filled in a slag-filled tank, and in this state, a cooling gas such as air is supplied into the slag-filled tank to remove the inherent heat of the granular solidified slag Sg. This is the process of recovering hot gas from the slag filling tank. The obtained high-temperature gas can be supplied to, for example, each process in a steelworks, thereby effectively utilizing the heat possessed by the molten slag S2. Further, the granular solidified slag Sg after heat recovery is discharged from the heat recovery equipment and then shipped as product slag. In this embodiment, highly efficient heat recovery is possible.

The steam recovery process is a process of generating steam using the slag heat of the obtained high-temperature granular solidified slag Sg and recovering it. This steam can be used to steam age any solidified slag.

Steam aging is the process of supplying steam to the resulting hot granular solidified slag Sg. As a result, the steam aging treatment is performed with the following formula (1) as the main reaction. The product slag thus obtained has undergone an expansion reaction by steam aging treatment, and can be shipped as steel slag for roads. In the present embodiment, since the total surface area of the granular solidified slag Sg is large, the penetration efficiency of steam into the slag is high, and efficient steam aging treatment is possible.
CaO + H ₂ O → Ca(OH) ₂ (1)

Carbonation treatment is a process of supplying carbon dioxide gas (CO ₂ ) to the obtained hot granular solidified slag Sg. As a result, a carbonation treatment is performed with the following formula (2) as the main reaction. The product slag thus obtained has undergone an expansion reaction through the carbonation treatment, and can be shipped as steel slag for roads. In this embodiment, since the total surface area of the granular solidified slag Sg is large, the efficiency of permeation of carbon dioxide gas into the slag is high, and efficient carbonation treatment is possible. As a result, _CO2 can be fixed, contributing to the reduction of _CO2 emissions.
CaO + CO ₂ → CaCO ₃ (2)

The classification process is a process of classifying the granular solidified slag Sg by a sieving method using sieve mesh, etc., and selecting granular solidified slag of a desired particle size. All or part of the granular solidified slag classified here can be reused as the granular solid S1 in this embodiment.

As the post-treatment, two or more selected from heat recovery treatment, steam recovery treatment, carbonation treatment, steam aging treatment, classification treatment, etc. may be combined, and the treatment order in that case is not particularly limited.

(Experimental example 1)
Solidification and crushing tests of molten slag were conducted using the production facility shown in FIG. Decarburized slag, which is a type of steelmaking slag, was used as the molten slag. The temperature of the molten slag is shown in Table 1. Decarburized slag (granular solid slag) obtained by the same process as the molten slag was used as the granular solid. The granular solid slag had a particle size distribution satisfying the CS-40 standard with a 37.5 mm sieve passage rate of 97% and a 19 mm sieve passage rate of 50%. However, No. in Table 1 where the solidified thickness is 27 mm or less. For 1 to 4, granular solid slag classified with a sieve having a maximum particle size or less was used so that the particle size of the granular solid was smaller than the target solidification thickness. For example, No. 1 with a solidification thickness of 15 mm. 1, a sieve with a nominal size of 13.2 mm and no. 2 and 3, a sieve with a nominal size of 19 mm and a No. 2 with a solidification thickness of 27 mm; In No. 4, granular solid slags each passed through a sieve with a nominal size of 26.5 mm were used. A layer of this granular solid slag was laid down in the mold. After that, molten slag was supplied into the mold so that the solidified thickness shown in Table 1 was obtained. The mass ratio of the particulate solids to the total mass of the particulate solids and molten slag was 25% as shown in Table 1. In this manner, the molten slag was solidified together with the particulate solid matter in the mold to obtain a plate-like solidified slag.

At this time, a thermocouple was set in the mold to measure the time until the plate-shaped solidified slag could be removed from the mold (time until all the molten slag solidified). Table 1 shows the results.

After that, the plate-shaped solidified slag at the charge temperature shown in Table 1 was placed in a rotary kiln and crushed for 10 minutes to obtain granular solidified slag. The charge temperature (average temperature of plate-shaped solidified slag at the time of charging) is calculated by specifying the range corresponding to the plate-shaped solidified slag from the thermal image taken using a thermoviewer and calculating the average temperature of that range. and asked.

The average temperature of the obtained granular solidified slag is also obtained by using a thermoviewer in the same manner as described above, that is, by specifying the range of the portion corresponding to the granular solidified slag from the photographed thermal image and calculating the average temperature in that range. Table 1 shows. In addition, a sieve test was performed on the granular solidified slag, and whether the total amount passed through a 53 mm sieve with a nominal opening of a metal mesh sieve specified in JIS Z 8801-1: 2019 (ISO 3310-1: 2016) The results are shown in Table 1. In addition, the particle shape determination volume ratio of coarse slag and the particle shape determination volume ratio of fine slag were measured by the method described above, and the results are shown in Table 1.

　No. In Comparative Examples 1 to 4, the thickness of the plate-like solidified slag obtained was thin, so the average slag temperature after crushing was lower than 1000°C. In addition, the 19 mm sieve passage rate was 80% or more, which was finer than the particle size distribution suitable for steel slag for roads. No. In Comparative Example 9, the granular solid slag floated on top of the molten slag poured into the mold, so the time to solidification was as long as 5.4 minutes. The 19 mm sieve passage rate was 42%, which was larger than the particle size distribution suitable for steel slag for roads. On the other hand, No. In invention examples 1 to 4, the 19 mm sieve passage rate fell within the range of 50 to 80% by mass, and a particle size distribution suitable for steel slag for roads was obtained.

(Experimental example 2)
The same test as in Experimental Example 1 was conducted by pouring only molten slag into the mold without supplying solid particles. Experimental conditions and experimental results are shown in Table 2.

　No. In comparative examples 10 to 14, it was almost impossible to crush the plate-shaped solidified slag in the rotary kiln. Therefore, the crushing was terminated when the processing time in the rotating device reached 30 minutes. In any of the comparative examples, the 19 mm sieve passage rate was low, and a particle size distribution suitable for steel slag for roads could not be obtained. Therefore, it has been found that the presence of particulate solid matter is important for easily crushing plate-shaped solidified slag.

(Experimental example 3)
Under the experimental conditions shown in Table 3, the same test as in Experimental Example 1 was conducted. Experimental results are also shown in Table 3. No. In Comparative Examples 15 to 18, the time until solidification was long, and the shape of the granular solidified slag after crushing was not rounded, so the particle shape determination actual volume ratio was low. On the other hand, No. In invention examples 19 to 22, the time until solidification was short, and the shape of the granular solidified slag after crushing was rounded, so the particle shape determination actual volume rate was high.

(Experimental example 4)
Under the experimental conditions shown in Table 4, the same test as in Experimental Example 1 was conducted. That is, in addition to the granular solid slag, iron balls and waste concrete were adopted as the granular solids. No. 1 of Experimental Example 1 was used for any of the granular solids. Those having the same particle size distribution as 5-9 were used. For each particulate solid, the mass ratio of particulate solid to the total mass of particulate solid and molten slag was varied. Table 4 shows the experimental results.

As is clear from Table 4, by setting the mass ratio in the range of 10 to 40% by mass, the sieve passage rate of 19 mm falls within the range of 50 to 80% by mass, and a particle size distribution suitable for steel slag for roads is obtained. was taken.

According to the method and equipment for producing granular solidified slag of the present invention, granular solidified slag having a particle size distribution within the standard particle size range for road steel slag can be easily produced. In addition, since it is possible to obtain high-temperature granular solidified slag, when the granular solidified slag is subjected to heat recovery treatment, carbonation treatment, or steam aging treatment in the subsequent process, by effectively utilizing the heat of the granular solidified slag, It is possible to improve the efficiency of the post-process. Since this contributes to the reduction of _CO2 emissions, the present invention is an industrially very effective process.

100 granular solidified slag manufacturing facility 10 mold 20 granular solid supply device 20A hopper 20B gutter 30 molten slag supply device 30A tilt pan 30B gutter 40 rotating device (slag crushing device)
S1 Granular solid S2 Molten slag S Plate solidified slag Sg Granular solidified slag

Claims

feeding particulate solids and molten slag into a mold;
a step of solidifying the molten slag together with the granular solids in the mold to obtain a plate-like solidified slag having a thickness of 30 mm or more and 50 mm or less, which consists of a solidified region formed by solidifying the molten slag and the granular solids;
removing the plate-shaped solidified slag from the mold;
A step of charging the plate-shaped solidified slag into the cylindrical container of a rotating device having a rotating cylindrical container, rotating the cylindrical container to crush the plate-shaped solidified slag, and obtaining granular solidified slag. When,
A method for producing granular solidified slag.
2. The particulate solid material of claim 1, wherein the particulate solid material comprises one or more selected from particulate solid slag, particulate solid material having one or both of hydrates and carbonates formed thereon, and particulate solid iron. A method for producing granular solidified slag.
The granular solid slag and the granular solid material have a particle size range of 40 to 0 mm, and a nominal opening of a metal mesh sieve defined in JIS Z 8801-1:2019, and a sieve passage rate of 100% by mass of 53 mm, The sieve passage rate of 37.5 mm is 95 to 100% by mass, the sieve passage rate of 19 mm is 50 to 80% by mass, the sieve passage rate of 4.75 mm is 15 to 40% by mass, and the sieve passage rate of 2.36 mm is 5 to 3. The method for producing granular solidified slag according to claim 2, having a particle size distribution of 25% by mass.
The method for producing granular solidified slag according to claim 2, wherein the granular solid iron has a particle size range of 10 mm or more and 50 mm or less.
The granular solidified slag according to any one of claims 1 to 4, wherein the mass of the granular solid is 10% by mass or more and 40% by mass or less with respect to the total mass of the granular solid and the molten slag. Production method.
The granular solidified slag according to any one of claims 1 to 5, wherein the plate-shaped solidified slag has an average temperature of 600 ° C. or higher and 1250 ° C. or lower when charged into the cylindrical container of the rotating device. manufacturing method.
The rotating device crushes the plate-shaped solidified slag to a particle size of 53 mm or less, and at that time, the 19 mm sieve passage rate of the granular solidified slag is 50% by mass or more and 80% by mass or less. A method for producing granular solidified slag according to any one of claims 1 to 3.
Claim 1, wherein, of the granular solidified slag, a particle shape determination actual volume rate using coarse-grained slag adjusted to conform to the particle size distribution of crushed stone 2005 specified in JIS A 5005; 2020 is 50.0% or more. 8. A method for producing granular solidified slag according to any one of 1 to 7.
Among the granular solidified slag, the particle shape determination using fine-grained slag adjusted so as to conform to the particle size distribution of crushed sand specified in JIS A 5005; 9. The method for producing granular solidified slag according to any one of 8.
a mold, a particulate solid supply device that supplies particulate solids into the mold, and a molten slag supply device that supplies molten slag into the mold; a slag solidification facility for obtaining a plate-shaped solidified slag having a thickness of 30 mm or more and 50 mm or less composed of a solidified region formed by solidifying the molten slag and the granular solid matter by solidifying together with the object;
a rotating device comprising a rotating cylindrical container for crushing the plate-shaped solidified slag charged into the cylindrical container by rotating the cylindrical container to obtain granular solidified slag;
Production equipment for granular solidified slag.