JP6996485B2 - Method for manufacturing charcoal interior particles and method for manufacturing charcoal interior sintered ore - Google Patents

Description

The present invention relates to a technique for producing a sintered ore used as a raw material for iron making in a blast furnace or the like, and specifically, a method for producing a carbonaceous material interior particle containing a carbonaceous material and a method for producing the carbonaceous material interior particle and sintering the carbonaceous material interior particle. The present invention relates to a method for producing a carbonaceous interior sinter produced as a part of a raw material.

In the blast furnace ironmaking method, generally, iron-containing raw materials such as sinter, iron ore, and pellets are mainly used as an iron source. Here, the sinter is a kind of lump ore and is produced by the following procedure. That is, first, iron-containing raw materials such as iron ore and dust having a grain size of 10 mm or less, lime-containing raw materials such as limestone, fresh lime, and steelmaking slag, MgO-containing raw materials such as refined nickel slag, dolomite, and serpentine, and silica stone, etc. After adding an appropriate amount of water to a granulation raw material composed of a SiO ₂ -containing raw material composed of, a coagulant such as powdered iron ore and smokeless charcoal, the mixture is mixed and granulated using a drum mixer or the like to obtain pseudo particles, and then The pseudo-granulated raw material is charged onto a pallet that circulates and moves in the granulator, and the coagulant contained in the granulated raw material is burned to form a sintered cake, and then the sintered cake is crushed. Then, it is cooled, granulated, and the one having a certain particle size or more is recovered as a product sintered ore.

Conventionally, a method of uniformly liquid-phase sintering the entire charging layer (hereinafter referred to as a sintering bed) of a sintering machine has been the main method. However, in recent years, a sintering method has been studied in which a portion mainly composed of liquid phase sintering and a portion in which liquid phase formation is suppressed are mixed in a sintered bed as in the conventional case, and a non-uniform structure is intentionally aimed at. The reason is that many fine pores remain after firing in the portion having a high melting point and being difficult to melt, the contact area with the reducing gas increases, and a sintered ore structure that is easily reduced can be formed.

As a method for producing such a sinter, for example, in Patent Document 1, as a method for suppressing liquid phase formation at a high melting point, carbonaceous material interior particles in which a carbonaceous material is coated with iron ore powder and a CaO-containing raw material are produced. , A method of mixing this with a conventional sintering raw material mainly composed of liquid phase sintering and then sintering it in a downward suction type sintering machine is disclosed.

Japanese Patent No. 5790966

There is a problem that the carbonaceous material interior particles as disclosed in Patent Document 1 are pulverized before being charged into the sintering machine. As a method for improving the strength of the carbonaceous material interior particles in order to reduce this pulverization, a method of using cement powder as a compounding raw material for the carbonaceous material interior particles (Japanese Patent Application No. 2017-249329) can be considered. However, when cement powder is mixed with the compounding raw material, there is a problem that the carbonaceous material interior particles stick to each other depending on the water content in the compounding material, which makes transportation difficult and also causes the carbonaceous material interior particles to be generated in the sintering machine. There is also the harmful effect of not being dispersed.

Therefore, the present invention has been developed in view of the above-mentioned problems, and an object thereof is to prevent the particles of the carbonaceous material interior particles from sticking to each other at the stage of being transported to the sintering machine and charged. At the same time, it is intended to smoothly produce carbonaceous material interior particles and to propose a method for producing carbonaceous material interior type sinter.

As a result of diligent studies to solve the above problems, the inventors have found that it is effective to cure the granulated particles for a certain period of time, crush them once, and then perform further curing. The headline led to the development of the present invention. That is, in the present invention, first, by granulating a mixed raw material powder formed by mixing an iron-containing raw material, a lime-containing auxiliary raw material, and cement powder and a core carbon material, the above-mentioned is described around the carbon material core. The granulation step of forming the outer layer of the mixed raw material powder to obtain the carbonaceous material inner particles, the first curing step of allowing the carbonic material inner particles after the granulation to stand still, and the carbonaceous material after the first curing step. A method for producing carbonaceous interior particles, which comprises a crushing step of crushing the internal particles and a second curing step of allowing the crushed carbonaceous interior particles to stand after the above crushing step. suggest.

Regarding the method for producing the carbonaceous material interior particles according to the present invention, refer to the method.
a. The first curing process described above is that the curing period is 3 to 10 days.
b. The second curing step should be completed 20 days after the granulation step.
c. The first curing step is performed by accommodating the carbonaceous material interior particles in a flexible container bag.
Can be a more preferred solution.

Secondly, in the present invention, the carbonaceous material interior particles produced by the above method and the granulated particles for ordinary sinter production are mixed, and the mixed particles are charged into a downward suction type sinter. We propose a method for producing a carbonaceous interior sinter, which is characterized by sintering.

According to the present invention, it is possible to efficiently produce carbonaceous material interior particles having high crushing strength without the particles after granulation sticking to each other and agglomerating. Further, according to the present invention, it is possible to reduce the amount of carbonaceous material interior particles that disintegrate at the stage of being transported to the sintering machine and charged into the sintering machine. Moreover, by sintering the sinter raw material containing such sinter interior particles to produce the sinter interior sinter, a sinter structure that is easily reduced is formed, and a sinter with high reduction efficiency is produced. be able to.

It is a schematic diagram which shows an example of the granulation process of the carbonaceous material interior particle which concerns on one Embodiment of this invention. It is a photograph which shows the state of the carbonaceous material interior particle in the granulation machine which concerns on one Embodiment of this invention. It is a schematic diagram which shows an example of the manufacturing process of the carbonaceous material interior sinter which concerns on one Embodiment of this invention. It is a graph which shows the relationship between the crushing strength and the curing period of the carbonaceous material interior particle which concerns on one Embodiment of this invention. It is a graph which shows the relationship between the mass ratio of the carbonaceous material interior particle and the curing period which concerns on one Embodiment of this invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The first embodiment of the present invention relates to a method for producing carbonaceous material interior particles. FIG. 1 is a schematic diagram for explaining a method for producing carbonaceous material interior particles according to this embodiment, and shows an example of a granulation step 10.

In the granulation step 10 of the carbonaceous material interior particles, first, the iron ore powder 12 which is a powdery iron-containing raw material stored in the storage tank 14 and the lime-containing auxiliary raw material stored in the storage tank 18, for example, quicklime 16. And the cement powder 20 stored in the storage tank 22 are cut out from each storage tank in a predetermined amount on the transporter 24. The iron ore powder 12, the quicklime 16 and the cement powder 20 are transferred to a kneader 28 such as an intensive mixer by a transporter 24, and an appropriate amount of water 26 is added and mixed by the kneader 28 to obtain a mixed raw material powder 30.

In this embodiment, the iron ore powder 12 is an example of a powdery iron-containing raw material, and for example, iron ore powder having a particle size of 150 μm or less and a specific surface area of about 1500 cm ² / g is used. Quicklime 16 is an example of a lime-containing auxiliary material, and limestone [CaCO ₃ ] may be used in place of quicklime [CaO] or together with quicklime. However, from the viewpoint of granulating the mixed raw material powder 30, it is preferable to use quicklime having a high granulation effect. In addition, dolomite [CaMg (CO ₃ ) ₂ ], which increases the viscosity of the melt produced during sintering, may be added to quicklime and / or limestone. That is, the lime-containing auxiliary raw material is a raw material containing one or more selected from quicklime, limestone and dolomite, and does not contain cement.

The characteristic of the present invention is that cement powder 20 is blended in addition to the lime-containing auxiliary raw material. The cement powder 20 is a water-hard cement such as Portland cement, mixed cement, and blast furnace slag. Cement or the like is suitable. Since the cement powder 20 also contains lime, it is preferable to reduce the amount of the lime-containing auxiliary material cut out corresponding to the lime contained in the cement powder 20. In the following embodiment, Portland cement having the chemical composition shown in Table 1 below was used as the cement powder 20. Although the long-term strength of cement varies depending on the type, the strength of the present invention may be as long as 4 weeks or less, and the long-term strength of several months is not required. Therefore, in the present invention, any kind of cement can be used. In cold regions and the like, it is more preferable to use alumina cement because the strength is developed in a shorter time.

Next, the mixed raw material powder 30 mixed by the kneader 28 and the coke particles 32 which are the cores of the carbonaceous material stored in the storage tank 34 are cut out in a predetermined amount by the transport machine 36, granulated and granulated. It is a mixed raw material for use. In this embodiment, the mixed raw material powder 30 is such that the mixing ratio of the coke particles 32 to the mixed raw material for granulation is 1% by mass or more and 5% by mass or less, more preferably 2% by mass or more and 4% by mass or less. And the coke particles 32 are cut out.

Further, in this embodiment, the coke particles 32 are an example of the charcoal material, and the coke material 32 has an outer layer made of the mixed raw material powder 30 formed around the coke material to form a core of the charcoal material. As the charcoal material, for example, anthracite charcoal such as Hongei charcoal can be used. Since coke particles and Hongei charcoal have a small amount of volatile matter, the amount of combustion gas generated from the charcoal material during sintering can be reduced by using these, and the coal material interior sintered ore produced using the carbon material interior particles can be used. The decrease in strength can be suppressed. As a result, it is possible to suppress a decrease in the yield of the sinter for the interior of the carbonaceous material.

The above-mentioned mixed raw material for granulation is conveyed to a granulator 38 such as a disc pelletizer by a conveyor 36, rolled by the granulator 38 under the addition of an appropriate amount of water 26, and coke particles due to the cross-linking force of water or the like. 32 is the core of the carbonaceous material, and the carbonaceous material interior particles 40 having an outer layer made of the mixed raw material powder 30 formed (coated) around the core are produced.

FIG. 2 is a photograph showing the mixed raw material powder 30, coke particles 32 (including growing carbonaceous material interior particles), and carbonaceous material interior particles 40 existing in the granulator 38. The carbonaceous material interior particles 40 are manufactured according to the granulation step 10 of the carbonaceous material interior particles shown in FIG. 1, but if the strength of the carbonaceous material interior particles 40 is low, the carbon material interior particles 40 are conveyed to the sintering machine. There is a risk of collapse when charging into the sintering machine. Therefore, in the method for producing carbonaceous material interior particles according to the embodiment of the present invention, cement powder 20 is blended with iron ore powder 12 and quicklime 16. By blending (adding) the cement powder 20, the strength of the mixed raw material powder 30 formed as an outer layer around the coke particles 32 is increased, and the carbonaceous material is transferred to the sintering machine and charged into the sintering machine. The collapse of the interior particles 40 can be suppressed.

Next, measures for improving the strength of the carbonaceous material interior particles 40 will be described. As schematically shown in FIG. 3, the carbonaceous material interior particles 40 transfer to a plurality of conveyors from the time when the carbonaceous material interior particles 40 are manufactured to the time when they are charged into the downward suction type sintering machine 60. Become. Therefore, it is preferable that the carbonaceous material interior particles 40 have strength to withstand the connection between a plurality of conveyors and the impact at the time of loading the pallet of the lower suction type sintering machine 60. Therefore, we produced carbonaceous interior particles with different crushing strengths on a trial basis, and investigated the state of decay of the carbonaceous interior particles after the transfer of conveyors and the loading of pallets. As a result, by setting the crushing strength of the carbonaceous material interior particles to 9.8 N / piece or more, it can withstand the impact of connecting multiple conveyors and the pallet loading of the downward suction type sintering machine 60 well, and downward suction. It has been found that direct delivery to the type sintering machine 60 is possible. In the present invention, the crushing strength is the maximum strength measured by compressing the carbonaceous material interior particles at a compression rate of 1 mm / min using a compression tester.

In order to increase the crushing strength of the carbonaceous material interior particles to 9.8 N / piece or more, in the case of iron ore powder containing hematite as the main mineral, an iron ore having a Braine specific surface area of about 1800 to 2000 cm ² / g or a particle size of 45 μm or less. It is necessary to use iron ore powder having a stone powder content of 80% by mass or more. However, most of the hematite concentrate fine powder currently distributed in the iron ore market has a Braine specific surface area of about 500 to 1500 cm ² / g and a content ratio of iron ore powder of about 45 μm or less of about 35 to 75% by mass. .. Therefore, even if these raw materials are used as they are, it is not possible to produce carbonaceous material interior particles having a crushing strength of 9.8 N / piece or more.

On the other hand, by crushing the iron ore powder using a ball mill or the like, the content ratio of the iron ore powder having a Braine specific surface area of 1800 cm ² / g or more or a particle size of 45 μm or less can be set to 80% by mass or more. The cost and running cost will be high. Therefore, in order to confirm whether or not the crushing strength of the carbonaceous material inner particles 40 can be increased to 9.8 N / piece or more by blending the cement powder 20 with the mixed raw material powder 30 of the outer layer formed around the carbonaceous material 32. The production test of the carbonaceous material interior particles was performed according to the granulation step 10 of the carbonaceous material interior particles 40 shown in FIG.

The production test of the carbonaceous material interior particles was carried out according to the following procedure. First, iron ore powder having a particle size of 150 μm or less and a Braine specific surface area of 1500 cm ² / g, fresh lime having a particle size of 75 μm or less, and cement powder having a particle size of 150 μm or less are mixed in a mass ratio of 95: 1: 4. And mixed uniformly using an intensive mixer to obtain a mixed raw material powder. This mixed raw material powder and coke particles having a particle size of 2 mm or more and 8 mm or less were mixed at a mass ratio of 98: 2 to prepare a mixed raw material for granulation. This mixed raw material for granulation was rolled using a disc pelletizer to granulate the mixed raw material for granulation, and the carbonaceous material inner particles in which the outer layer made of the mixed raw material powder was formed around the carbonaceous material were produced. The water required for granulation of the mixed raw material for granulation was supplied by spraying an appropriate amount into an intensive mixer and a disc pelletizer.

The first curing step of allowing the carbonaceous interior particles after granulation to stand still was performed. In this first curing step, work is performed to protect the material from being adversely affected by vibration and external force during the progress of curing by cement or the like. In general, hardening of cement is a reaction with water (hydration reaction) and is affected by humidity. Therefore, especially in the early stage of hardening, avoiding strong wind and direct sunlight to reduce the evaporation of water, or heat retention. It is preferable to promote the progress of the hydration reaction or suppress the freezing of water by supplying heat or heat. The packaging of the carbonaceous material interior particles in this first curing process is not particularly limited, but if curing is performed while housed in a flexible container (flexible container bag), the water retention effect will release the water required for cement hardening. It is desirable because the curing is more homogenized because it is kept at a high level as a whole including the surface layer. In addition, when curing is performed while housed in a flexible container, the above-mentioned water retention effect suppresses heat removal due to the heat of vaporization of water, and also suppresses the dissipation of reaction heat due to the hardening of cement. It is desirable because the temperature of the material interior particles can be kept equal to or higher than the temperature of the outside air. Further, it is desirable to perform curing while the particles are housed in a flexible container because even if some of the carbonaceous material interior particles adhere to each other, they can be crushed without applying excessive force and pulverization can be further suppressed.

Next, following the first curing step, a crushing step for crushing the carbonaceous material interior particles was provided. Here, the above-mentioned crushing means that when a plurality of granulated carbonaceous material interior particles adhere to each other to form a nodule, the adhesion is loosened and the particles are returned to the same disjointed state as immediately after granulation or brought closer to each other. Is. For example, the work itself of moving from the place where the first curing process was performed or discharging from the flexible container will break the adhesion between the carbonaceous interior particles. Further, in order to sieve and remove the powder, for example, the work of sieving with a mesh opening of 4 mm also has a crushing action of breaking the adhesion between the carbonaceous material interior particles.

If the agglomeration of the carbonaceous interior particles is still not resolved by the above-mentioned work, the particles can be crushed by repeating the movement or by giving an impact with a heavy machine to loosen them. Adhesion between carbonaceous interior particles As long as nodules do not progress, it is easy to transport and loosen the adhesion, and the amount of powdered carbonaceous interior particles themselves when loosening can be reduced. Therefore, it is desirable to crush the carbonaceous material interior particles while the agglomeration of the adhesive nodules is slight. However, when the adhesion of the carbonaceous interior particles to each other is slight, that is, when the curing period is short, the strength of the carbonaceous interior particles themselves is not sufficient, and when they are transported by a conveyor or the like and stored in a storage tank. It may be crushed and easily powdered.

Therefore, after the crushing step, it was decided to provide a second curing step in which the carbonaceous material interior particles are allowed to stand again. By performing such a second curing step, it is possible to obtain carbonaceous material interior particles having a higher crushing strength than after the first curing step. The charcoal interior particles once crushed are characterized in that nodule formation hardly progresses in the second curing step.
As is clear from the above description, in the method for producing carbonaceous interior particles according to the present invention, after the granulation step 10 of the carbonaceous material interior particles, the first curing step, the crushing step, and the first. It is necessary to go through the second curing process.

FIG. 4 is a graph showing the relationship between the curing period and the crushing strength of the carbonaceous material interior particles. In FIG. 4, the horizontal axis is the curing period (days), and the vertical axis is the crushing strength (N / piece) of the carbonaceous material interior particles. Further, in FIG. 4, the white circle plot shows the measured value of the crushing strength, and the black circle plot shows the average value of the crushing strength. As shown in FIG. 4, the crushing strength of the carbonaceous interior particles may be 9.8 N / piece or more even one day after curing, and the crushing strength of almost the entire amount of the carbonaceous interior particles is 9 three days after curing. It is considered to be 8.8N / piece or more. Further, it can be seen that if the curing period is set to 20 days or more, the strength increases to 49 N / piece or more, which is a crushing strength that does not collapse even when handled with a heavy machine or a reclaimer after curing.

FIG. 5 is a graph showing the relationship between the curing period and the mass ratio of the carbonaceous material interior particles. Here, the agglomeration ratio indicates the ratio of the agglomerated carbonaceous material interior particles among the cured carbonaceous material interior particles by mass ratio. The mass ratio (mass%) increased as the curing period (days) became longer, and the mass ratio exceeded 80% by mass after 15 days. In addition, as the lump ratio increases, the lump becomes larger, which may make handling difficult. In order to reduce the mass ratio to 10% by mass or less for easy handling, it is desirable that the first-stage curing period (first curing step) is 10 days or less. Further, when the lump ratio was 10% by mass or less, the bond between the carbonaceous interior particles constituting the lump was not strong, so that the majority of the particles returned to the same disjointed state as immediately after granulation during handling.

Next, a method for producing a carbonaceous interior sintered ore, which is a second embodiment of the present invention, will be described. FIG. 3 is a schematic view showing an example of a production process 100 of a carbonaceous interior sintered ore in which a method for producing a carbonaceous interior sintered ore can be carried out. In the production process 100 of the carbon material interior sintered ore, in parallel with the granulation step 10 of the carbon material interior particles 40 shown in FIG. 1, iron-containing raw materials such as iron ore and dust having a particle size of 10 mm or less and limestone. A raw material 50 containing an auxiliary raw material containing CaO-containing raw materials such as fresh lime and steel slag and a coagulant composed of powdered coke and smokeless charcoal having a particle size of less than 3 mm is granulated by a granulator 52 such as a drum mixer. To produce ordinary granulated particles 54 for producing sintered ore. The auxiliary raw material may include an MgO-containing raw material such as refined nickel slag, dolomite, and serpentinite, and a SiO ₂ -containing raw material made of silica stone or the like.

Next, the carbonaceous material interior particles 40 are mixed with the ordinary granulated particles 54 for producing sinter, which are obtained by granulating the raw material 50, to obtain mixed particles 56. Of the mixed particles 56, the ordinary granulated particles 54 for producing sinter are mainly liquid phase sintered parts, and the carbonaceous material inner particles 40 are the parts where liquid phase formation is suppressed. In the present embodiment, it is preferable to add the carbonaceous material interior particles 40 to the granulated particles 54 so that the mixing ratio of the carbonaceous material interior particles 40 with respect to the mixed particles 56 is 10% by mass or more and 30% by mass or less. As a result, the air permeability of the mixed particles 56 is improved, and the productivity of the carbonaceous material interior sinter is improved.

The mixed particles 56 mixed with the carbonaceous material interior particles 40 are carried into the surge hopper of the downward suction type sintering machine 60. The mixed particles 56 are charged from the surge hopper into an endlessly movable pallet to form an charging layer. The charge layer is ignited by an ignition furnace installed above, and the charge layer is sequentially burned and sintered by sucking the upper gas downward from the wind box installed below. The charging layer is sintered by the combustion heat generated by the combustion to form a sintered cake. The sintered cake is crushed and sized at the sinter portion, and agglomerates having a particle size of 4 mm or more are recovered as an adult carbonaceous interior sintered ore. The carbonaceous interior sinter produced in this way is used as a raw material for iron production in the blast furnace 70. The particle size in the present embodiment is a particle size sieved using a sieve having a nominal opening according to JIS (Japanese Industrial Standards) Z8801-1: 2006, and is, for example, a particle size of 4 mm or more. Refers to the particle size to be sieved on a sieve using a sieve having a nominal opening of 4 mm according to JIS Z 8801-1: 2006.

The particle size of the charcoal material used in the method for producing the carbonaceous material interior particles according to this embodiment is preferably 2 mm or more. By using a carbonaceous material having a particle size of 2 mm or more, it is possible to prevent the carbonaceous material core from disappearing in the step of sintering the mixed particles mixed with the carbonaceous material interior particles with a sintering machine. The particle size of the carbonaceous material is more preferably 3 mm or more. By using a charcoal material having a particle size of 3 mm or more, the disappearance of the charcoal material can be further suppressed.

On the other hand, when a charcoal material having a large particle size is used, the amount of combustion gas generated from the charcoal material during sintering increases, and cracks occur in the outer layer covering the coal material core in the coal material inner sintered ore. When a crack occurs in the outer layer covering the carbonaceous core, the strength of the carbonaceous interior sinter is greatly reduced, and as a result, the yield of the carbonaceous interior sinter is greatly reduced. Therefore, the particle size of the carbonaceous material is preferably 8 mm or less, and more preferably 6 mm or less.

Further, the particle size of the produced carbonaceous material interior particles 40 is preferably 8 mm or more and 18 mm or less. As described above, the carbonaceous interior sinter having a particle size of 4 mm or more is recovered as a product sinter, and the sinter having a particle size of less than 4 mm is recycled (returned) into a sinter raw material. Further, when the carbonaceous material interior particles 40 are sintered by a sintering machine, the volume becomes smaller due to evaporation of water or partial melting. Therefore, the particle size of the carbonaceous material interior particles 40 is preferably 8 mm or more, and more preferably 10 mm or more so that even if the carbonaceous material interior particles 40 are sintered as they are, they do not return ore.

The thickness of the outer layer formed on the carbonaceous material interior particles 40 is preferably 2 mm or more at the thinnest point. If it is less than 2 mm, the barrier effect of the sintered outer layer is insufficient, and the carbonaceous material core may burn and disappear during sintering. On the other hand, if the thickness of the outer layer formed on the carbon material interior particles 40 exceeds 5 mm, it becomes difficult to sinter all the outer layers of the carbon material interior particles 40 within a limited sintering time. If a portion of insufficient sinter is present in the sinter inside the sinter, the strength of the sinter inside the sinter is reduced and the yield of the sinter inside the sinter is reduced. Therefore, the thickness of the outer layer of the carbonaceous material interior particles 40 is preferably 5 mm or less. For example, the particles of the carbonaceous material interior particles when the particle size of the coke particles 32 is 8 mm and the thickness of the outer layer is 5 mm. The diameter will be 18 mm. Therefore, the particle size of the carbonaceous material interior particles 40 is preferably 18 mm or less.

In the method for producing carbonaceous interior particles according to this embodiment, cement powder 20 is mixed with the mixed raw material powder to increase the strength of the carbonaceous interior particles 40 produced by the cement powder 20. Since cement powder is inexpensive, its production cost control effect is enhanced by using it in a mass production process such as the production of sinter.

The technique of the present invention is not limited to the above-described embodiment, for example, a sintering technique for supplying gaseous fuel in addition to the carbonaceous material added to the sintering raw material as a sintering heat source. Further, it can be applied to a sintering technique for enriching and supplying oxygen.

10 Granulation process of carbonaceous material interior particles 12 Iron ore powder 14 Storage tank 16 Fresh lime 18 Storage tank 20 Cement powder 22 Storage tank 24 Transporter 26 Water 28 Kneader 30 Mixing raw material powder 32 Coke particles 34 Storage tank 36 Transporter 38 Granulation Machine 40 Charcoal interior particles 50 Raw material 52 Granulation machine 54 Granulation particles 56 Mixed particles 60 Downward suction type sintering machine 70 blast furnace 100 Charcoal interior sintered ore manufacturing process

Claims (5)

By granulating a mixed raw material powder made by mixing an iron-containing raw material, a lime-containing auxiliary raw material and cement powder, and a carbonaceous material having a core particle size of 2 mm or more and 8 mm or less, the mixing ratio to the mixed raw material for granulation is 1. A granulation step of forming an outer layer of the mixed raw material powder around a carbonaceous material core having a mass% or more and 5% by mass or less to obtain carbonaceous material internal particles.
The first curing step of allowing the carbonaceous interior particles after granulation to stand still, and
After the first curing step, a crushing step of crushing the carbonaceous material interior particles and a crushing step.
A second curing step in which the crushed carbonaceous material interior particles are allowed to stand after the crushing step, and
A method for manufacturing carbonaceous interior particles, which is characterized by passing through. The method for producing carbonaceous interior particles according to claim 1, wherein the first curing step has a curing period of 3 to 10 days. The method for producing carbonaceous interior particles according to claim 1 or 2, wherein the second curing step is completed 20 days after the granulation step. The method for producing carbonaceous interior particles according to any one of claims 1 to 3, wherein the first curing step is performed by accommodating the carbonaceous material interior particles in a flexible container bag. The carbonaceous material interior particles produced by the method according to any one of claims 1 to 4.
A method for producing a carbonaceous interior sinter, which comprises mixing ordinary granulated particles for sinter production and charging the mixed particles into a downward suction type sinter to sinter.

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