JP7073962B2 - How to charge the bellless blast furnace - Google Patents

Description

The present invention relates to a method for charging a bellless blast furnace.

In the operation of a blast furnace, there is a method of forming an ore layer and a coke layer by alternately charging ore as an iron source and coke as a reducing agent.

There is also a method of mixing coke with the ore and charging it. This is because coke is less likely to soften at the temperature inside the furnace than ore, so that the air permeability of the ore layer can be improved. In addition, the reactivity is improved by bringing the coke and the ore close to each other.

In the method of mixing and charging coke into the ore, the coke distribution in the mixed layer may be biased in the furnace radial direction. This is because coke and ore have different densities and particle diameters, so that the depositing position when stored in the furnace top hopper is different, and the ore is discharged before coke. That is, in the furnace top hopper, ores such as sinter tend to be deposited in the vicinity of the central portion, and coke tends to be deposited in the periphery. Therefore, when cutting out from the furnace top hopper, the funnel flow preferentially discharges the sinter directly above the discharge port, and the coke in the peripheral portion is discharged with a delay.

Therefore, in the method of mixing and charging coke into ore, it is necessary to adjust the coke distribution in the mixed layer.

As a specific adjustment method, the discharge port of the hopper is closed once in the middle of charging the first batch of mixed ore with coke, the second batch of ore is put into the hopper, and the discharge port is opened again for charging. There is known a method of discharging coke at the initial stage of the second batch by resuming the above (Patent Document 1).

By first charging the mixed raw material of ore and coke in a forward tilt, and then turning it back in the middle and charging it in a reverse tilt, one batch of mixed raw material is charged, and the coke distribution in the mixed layer is distributed in the furnace radial direction. A method of making it uniform is also known (Patent Document 2).

A method of dividing the mixed raw material into two batches and increasing the amount of coke mixed in the second batch more than that in the first batch is also known (Patent Document 3).
A method is also known in which the mixed raw material is divided into two batches, the amount of coke mixed with the mixed raw materials is as large as 60 to 75% by mass, and the second batch is charged to the furnace wall side (Patent Document). 4).
A method is also known in which the mixed raw material is divided into two batches, and the first batch is charged to the furnace center side and the second batch is charged to the furnace wall side by reverse tilting (Patent Document 5).

Patent No. 6102497 Japanese Unexamined Patent Publication No. 2015-134941 Patent No. 4114626 Patent No. 5776866 International Publication No. 2017/073053

However, the techniques described in Patent Documents 1 to 5 have the following problems.
The technique described in Patent Document 1 requires opening and closing of the discharge port of the hopper during charging. There is a problem that accurate charging is difficult due to the limitation of mechanical structural accuracy in charging with such mechanical movement. In addition, there is also a problem that mechanical failure is likely to occur.

Although the distribution of coke can be adjusted by the technique described in Patent Document 2, there is a problem that it is difficult to adjust the particle size distribution of the ore charged by the reverse tilt because the combination of the forward tilt and the reverse tilt is indispensable.

Although the technique described in Patent Document 3 can prevent coke segregation to some extent, it is difficult to precisely adjust the coke distribution in the radial direction only by increasing the coke mixing amount in the second batch more than that in the first batch. rice field.

The technique described in Patent Document 4 has a problem that it is difficult to form a coke layer because 60% or more of the amount of coke per charge is used for the mixed layer.

Although the technique described in Patent Document 5 can prevent coke segregation to some extent, the coke distribution in the radial direction of the first batch and the second batch overlaps to form a biased distribution having two peaks, so that the coke distribution is in the radial direction. It was difficult to make precise adjustments to the coke distribution. In addition, since the mixed raw material is charged by reverse tilting, there is also a problem that it is difficult to adjust the particle size distribution of the ore.

The present invention has been made in view of the above problems, and when coke is mixed with ore and charged, the radial distribution of coke in the mixed layer can be made more uniform than before, and the charging of a bellless blast furnace can be performed. The purpose is to provide a method.

In the charging method of the bellless blast furnace of the present invention, the mixed raw material of ore and coke is temporarily stored in the top hopper, and the mixed raw material is charged into the furnace from the top hopper by a swivel chute to form a mixed layer. In the method, the coke has an integrated non-dimensional charge amount of 0.1 to 0.45 when the non-dimensional discharge time of the mixed raw material is 0.5, and when the central coke layer is formed, there is no furnace opening. If the mixed raw material is deposited by forward tilting from a position with a dimensional radius of 0.7 to 1.0 to a position where it overlaps a part or all of the central coke, and the central coke layer is not formed, the blast furnace opening has no dimensional radius. The first mixed raw material charging step of depositing the mixed raw material by forward tilting from the position of 0.7 to 1.0 to the position of the furnace opening dimensionless radius of 0 to 0.2, and the furnace opening dimensionless radius of 0. It is characterized by carrying out a second mixed raw material charging step of depositing the mixed raw material by forward tilting from a position of 8 to 1.0 to a position of a furnace mouth dimensionless radius of 0.3 to 0.5. ..
According to the present invention, the mixed raw material is divided into two batches, one is a step of charging the mixed raw material from the vicinity of the furnace wall to the vicinity of the center of the furnace in a forward tilting manner, and the other is charging the mixed raw material from the vicinity of the furnace wall to the middle portion in the furnace by the forward tilting. Make an entry. Therefore, the coke distributions of the first batch and the second batch do not have two extreme peaks, and coke can be charged uniformly in the radial direction. In addition, since both batches are tilted forward, it is easy to adjust the particle size distribution of the ore.

The coke is preferably small coke.
In the present invention, since the small coke is mixed with the mixed raw material, it is easy to satisfy the condition that the cumulative non-dimensional charge amount is 0.1 to 0.45 when the non-dimensional discharge time is 0.5.
In the present invention, after the second mixed raw material charging step, it is preferable to carry out an ore charging step in which an ore in which coke is not mixed is charged on the mixed layer to form an ore layer.
Further, in the present invention, after the second mixed raw material charging step, an ore mixed with coke at a mixing ratio lower than that of the mixed raw material is charged onto the mixed layer to form an ore layer. It is preferable to carry out the ore charging process.
According to the present invention, since the ore layer in which the coke is not mixed or the mixing ratio of the coke is small is formed on the mixed layer, the coke in the mixed layer is less likely to come into contact with the coke in the coke layer. Therefore, the effect of ensuring the air permeability of the ore layer and improving the reactivity by mixing coke can be further enhanced, and more stable and high reduction rate operation can be realized.

The flow chart which shows the outline of the charging method of the bellless blast furnace which concerns on this embodiment. It is sectional drawing which shows the mixed raw material which was charged when the central coke was not charged by the charging method of the bellless blast furnace which concerns on this Embodiment, (A) is after O1 batch charging, (B) is O2. After the batch is charged, (C) is a diagram showing after the O3 batch is charged. The figure which shows the relationship between the dimensionless discharge time of the mixed raw material to be charged and the total dimensionless charge amount of coke in Example 1. FIG. The figure which shows the layer thickness ratio of O1 batch and O2 batch in Example 1. FIG. In Example 1, it is a figure which shows the relationship between the dimensionless radius of a furnace mouth and the dimensionless deposit amount of coke of a mixed layer, (A) is a predicted value, (B) is an experimental value. The figure which shows the model experimental apparatus used in an Example. In the second embodiment, the figure which shows the relationship between the dimensionless discharge time of the mixed raw material to be charged, and the total dimensionless charge amount of coke in a mixed layer. The figure which shows the layer thickness ratio of O1 batch and O2 batch in Example 2. FIG. In Example 2, it is a figure which shows the relationship between the dimensionless radius of a furnace mouth and the dimensionless deposit amount of coke in a mixed layer, (A) shows a predicted value, (B) shows an experimental value. In the comparative example, the figure which shows the relationship between the dimensionless radius of a furnace mouth and the dimensionless deposition amount of coke in a mixed layer.

Hereinafter, embodiments suitable for the present invention will be described in detail with reference to the drawings.
First, with reference to FIG. 1, the outline of the charging method of the bellless blast furnace according to the present embodiment will be described.

First, when the central coke layer is formed, the mixed raw material is deposited by forward tilting from the position of the furnace mouth dimensionless radius of 0.7 to 1.0 to the position where it overlaps with at least a part of the central coke layer. When the central coke layer is not formed, the mixed raw material is deposited by forward tilting from the position of the furnace opening dimensionless radius 0.7 to 1.0 to the position of the furnace opening dimensionless radius 0 to 0.2 (Fig. 1). S1, first mixed raw material charging step).

Next, the mixed raw materials are deposited by forward tilting from the position of the furnace opening dimensionless radius 0.8 to 1.0 to the position of the furnace opening dimensionless radius 0.3 to 0.5 (S2 in FIG. 1, No. 1). 2 mixed raw material charging step).

Further, if necessary, after S2, ore is charged on the mixed layer to form an ore layer (S3 in FIG. 1, the ore charging step).
The above is the outline of the charging method of the bellless blast furnace according to the present embodiment.

Next, the details of the charging method of the bellless blast furnace according to the present embodiment will be described.
<Target blast furnace>
If the charging method according to the present embodiment is a bellless blast furnace, the structure and dimensions of the target blast furnace are not particularly limited. A blast furnace is a blast furnace having a bellless charging device.
The charging method according to the present embodiment is limited to the case where the mixed raw material is temporarily stored in the furnace top hopper and charged into the furnace from the furnace top hopper by a swivel chute to form a mixed layer. When the mixed raw material is not temporarily stored in the furnace top hopper, that is, when the ore and coke stored in different hoppers are simultaneously cut out and charged into the furnace, the effect of segregation in the furnace top hopper described above This is because the timing of coke charging into the blast furnace can be arbitrarily controlled, and there is no problem that the coke distribution in the mixed layer is biased in the furnace radial direction.
The operating conditions are not particularly limited except that the mixed raw material of ore and coke is charged.

The type of coke is not particularly limited. Ordinary chunk coke can be used. However, when the dimensionless discharge time of the mixed raw material is 0.5, the cumulative dimensionless charging amount needs to be 0.1 to 0.45. If it exceeds 0.45, coke does not segregate even if this embodiment is not carried out. If it is less than 0.1 range, the coke will not be uniformly distributed even if the charging method of the present embodiment is used. More preferably, the cumulative dimensionless charging amount is 0.2 to 0.4 when the dimensionless discharge time of the mixed raw material is 0.5.
As such coke, small coke is preferable. The small-lump coke referred to here is under a coke sieve forming a coke layer, and is, for example, coke having a particle diameter of about 10 to 40 mm. In the following description, an example using small coke will be described. Further, the ore is a general term for iron-containing raw materials charged into a blast furnace, and refers to sinter, lump ore, pellets and coal-containing lump ore, and a mixture thereof.
The number of batches per charge and the particle size of ore and coke are not limited except for the requirements specified in S1 to S3. The mixing ratio is also not particularly limited. The pig iron ratio is not particularly limited.
The particle size and charging conditions of the coke forming the coke layer are not particularly limited. The central coke may or may not be charged.

In the following description, as shown in FIG. 2, the C1 batch was charged as the coke layer 201 in the furnace radial direction, and the mixed layer 202 was charged separately into the O1 batch and the O2 batch without charging the central coke. Although the case will be described as an example, a C2 batch may be charged as a central coke in the center of the furnace.

<S1: First mixed raw material charging process>
In S1, when the central coke is not charged, as shown in FIG. 2 (A), from the position of the furnace opening dimensionless radius 0.7 to 1.0 to the position of the furnace opening dimensionless radius 0 to 0.2. Up to P1, a part of the mixed raw materials constituting the mixed layer 202 is charged in a forward tilt. When charging the central coke, a part of the mixed raw material constituting the mixed layer 202 is charged from the position of the furnace opening dimensionless radius 0.7 to 1.0 to the position P1 overlapping a part or all of the central coke. Charge with forward tilt.
Here, the mixed raw material charged in S1 is referred to as an O1 batch.
The furnace mouth dimensionless radius is the position P at r / R when the furnace center is 0, the furnace wall is 1, the furnace diameter is R, and the distance from the furnace center at the radius position P in the furnace diameter direction is r. It is a represented value (see FIGS. 2A and 2B).

<S2: Second mixed raw material charging process>
In S2, from the position of the furnace opening dimensionless radius 0.8 to 1.0 to the position of the furnace opening dimensionless radius 0.3 to 0.5, among the mixed raw materials constituting the mixing layer 202, S1 is charged. The remaining residue is charged in a forward tilt (S2 in FIG. 1, the second mixed raw material charging step).
Here, the mixed raw material charged in S2 is referred to as an O2 batch.
FIG. 2 (B) shows the distribution of the charged materials in the blast furnace of the mixed raw materials after the end of S2.

By carrying out S1, the O1 batch is charged in substantially the entire area where the mixed layer 202 should be formed. However, since the ore is discharged before the small coke 100 at the time of charging, the small coke 100 is segregated on the center side of the furnace, and the furnace wall side, that is, the furnace opening dimensionless radius 0.8 to The small coke 100 is not sufficiently mixed in the mixed layer 202 in the range of the furnace mouth dimensionless radius of 0.3 to 0.5 from the position of 1.0. In S2, by charging the O2 batch only to the furnace wall side, the O1 batch overlaps with the O2 batch only in the region where the small coke content is small on the furnace wall side. Therefore, the difference between the amount of small coke in the mixed layer 202 on the furnace wall side of the O1 batch and the O2 batch combined and the amount of small coke in the mixed layer 202 on the furnace center side of only the O1 batch becomes small, and the radial direction It is possible to suppress the uneven distribution of the small coke 100. The reason why the end of the furnace center side of the charging range of S2 should be set to the position of the furnace mouth dimensionless radius of 0.3 to 0.5 will be described in detail in Examples.
Further, since both the O1 batch and the O2 batch are charged in a forward tilt, it is easy to adjust the particle size distribution of the ore.

The layer thickness ratio of the O1 batch and the O2 batch is the small coke in the mixed layer 202 in consideration of the raw material discharge characteristics from the furnace top hopper 3 due to the density difference and the particle size difference between the ore and the small coke 100. It may be appropriately set so that the radial distribution of 100 is made uniform to a desired degree.

The method for setting the layer thickness ratio is not particularly limited, but the following methods can be exemplified.
First, the distribution of the absolute value of the layer thickness of the mixed layer 202, here, the layer thickness distribution of the surface of the mixed layer 202 of FIG. 2B is set. Since the mass ratio (O / C) of the coke layer and the ore layer is predetermined as an operating condition, the layer thickness of the mixed layer 202 is determined in relation to the layer thickness of the coke layer 201.

Next, the relationship between the dimensionless discharge time of the mixed raw material to be charged and the integrated dimensionless charging amount of small coke in the mixed raw material is obtained. The relationship between the dimensionless discharge time of the mixed raw material and the cumulative non-dimensional charge amount of small mass coke in the mixed raw material may be obtained by a test device, a sampling test during a rest period, or a past operation record. For example, Discrete Element Method (DEM) and "Development of Bellless charge distribution simulation model based on full-scale model experiment" (Yoshimasa Kajiwara et al., Iron and Steel Vol. 71 (1985) No. 2, p.175- It may be obtained by numerical calculation using an emission simulation model as disclosed in 182).

The dimensionless discharge time of the mixed raw material is the elapsed time when T is the time required to complete the discharge of the mixed raw material and t is the arbitrary time elapsed from the start of the discharge of the mixed raw material. It is expressed in t / T.

The cumulative non-dimensional charge amount of small coke is the small amount (mass) of small coke charged in the mixed raw material at the time when the discharge of the mixed raw material is completed, and the small amount in the non-dimensional discharge time t / T. When the cumulative charge amount (mass) of the lump coke is m, the cumulative charge amount of the small coke is expressed in m / M. When determining the relationship between the non-dimensional discharge time of the mixed raw material and the cumulative non-dimensional charging amount of small coke in the mixed raw material using a test device or an actual furnace, the mixed raw material is sampled at regular time intervals and sampled. Let M be the mass of all the small coke produced, and m be the mass of the integrated small coke sampled up to a certain point in time corresponding to the dimensionless discharge time t / T.
FIG. 3 shows an example of the relationship between the obtained dimensionless discharge time of the mixed raw material and the integrated dimensionless charging amount of small coke in the mixed raw material.

Next, the layer thickness ratio is obtained so that the distribution of small coke in the radial direction of the mixed raw material to be charged becomes as uniform as possible. For example, the radial small coke distribution of the mixed raw material is calculated while changing the layer thickness ratio, and the layer thickness ratio at which the small coke distribution is most uniform is obtained. The work of changing the layer thickness ratio also includes changing the charging range of each of the O1 batch and the O2 batch.

An example of the layer thickness ratio is shown in FIG. FIG. 5A shows the results of calculating the radial small coke distribution of the mixed raw material with the layer thickness ratio shown in FIG. 4. In FIG. 5A, the small coke distribution is shown in relation to the dimensionless radius of the furnace mouth and the dimensionless deposit amount. The dimensionless deposit is the ratio of the deposit amount (volume) of the small coke 100 when the deposit amount (volume) of the mixed raw material at each position in the radial direction of the mixed layer 202 is 1.

By setting the layer thickness ratio of the O1 batch and the O2 batch, the amount of the mixed raw material charged by the O1 batch and the O2 batch is also determined. In the above description, the distribution of the small coke 100 to each batch is set in advance, but the coke 100 in the mixed layer is distributed to each batch in the radial direction so as to be more uniform. The distribution of the small coke 100 may be adjusted.

<S3: Ore charging process>
S3 is a step of charging the ore on the mixed layer 202 to form the ore layer 203, and is carried out as necessary (see FIG. 2C). Here, the ore charged in S3 is referred to as an O3 batch.

Do not mix coke in O3 batches, or mix coke in lesser mixing ratios than in O1 and O2 batches. The mixing ratio is similarly determined as the mass ratio of the mass of coke to the mass of the ore raw material for the small coke 100 and other coke.
Since the ore layer 203 is formed on the mixed layer 202, the coke layer 201 of the next charge is not formed directly on the mixed layer 202, so that the small coke 100 in the mixed layer 202 becomes the coke of the coke layer 201. It becomes difficult to contact. Therefore, by mixing the small coke 100 with the mixed layer 202, the effect of ensuring the air permeability and improving the reactivity of the mixed layer 202 and the ore layer 203 can be further enhanced, and more stable and high reduction rate operation can be performed. realizable.

The layer thickness of the O3 batch is not particularly limited, but is about 0.05 to 0.4 (relative thickness when the entire ore layer is 1.0).
The particle size of the ore in the O3 batch is not particularly specified, but it is preferably about the same as the particle size of the ore in the O1 batch and the O2 batch.
The above is a detailed explanation of the charging method of the bellless blast furnace according to the present embodiment.

As described above, according to the present embodiment, the mixed raw material is charged in a forward tilting manner from the vicinity of the furnace wall to the vicinity of the furnace center (S1) and from the vicinity of the furnace wall to the intermediate portion in the furnace by the forward tilting. The charging is performed separately in the step (S2). Therefore, the small coke distribution in the furnace diameter direction in the mixed layer 202, which is a combination of the O1 batch and the O2 batch, does not have two extreme peaks, and the small coke can be uniformly charged in the furnace diameter direction. Further, since both the O1 batch and the O2 batch are forwardly inclined, it is easy to adjust the particle size distribution of the ore.

Hereinafter, the present invention will be specifically described based on Examples, but the present invention is not limited to Examples.

(Example 1)
The blast furnace charging distribution experiment of this embodiment was carried out using a 1/3 scale model experimental device of the blast furnace. The specific procedure is as follows.
First, as an experimental device, the model experimental device 11 shown in FIG. 6 was prepared.

The model experimental device 11 is a charge hopper 1, a charge conveyor 2, a furnace top hopper 3, a swivel chute 4, a furnace body shaft portion 5, and is a 1/3 model of the charge charge device and the upper part of the blast furnace body. And a cutting device 6.

The surge hopper 1 is a storage for storing coke and ore as raw materials for charging.
The charging conveyor 2 is a conveyor that conveys the charging raw material cut out from the surge hopper 1 to the furnace top hopper 3. The furnace top hopper 3 is a hopper that temporarily stores raw materials immediately before charging. The swivel chute 4 is a chute for charging the raw material discharged from the furnace top hopper 3. The furnace body shaft portion 5 is a cylindrical model simulating up to the shaft portion of the blast furnace. The cutting device 6 is provided at the lower end of the furnace body shaft portion 5 and is a device for cutting out the charged raw material and reproducing the unloading in the furnace.

Next, sinter as an ore and small coke 100 were prepared as mixed raw materials. Specifically, the average particle size was set to about 1/3 of the average particle size assumed in the actual furnace. The sinter had an average particle diameter of 7.7 mm and a density of 3.3 g / cm ³ . The small coke 100 had an average particle diameter of 10.8 mm and a density of 1.0 g / cm ³ . The particle size ratio of the small coke 100 to the sinter was 1.40, and the density ratio was 0.3.

Next, the raw material is cut out from the surge hopper 1 and stored in the furnace top hopper 3 via the charging conveyor 2, and when the raw material is put into the swivel chute 4, the raw material is collected, the ratio of the small coke 100 is measured, and the mixture is mixed. The relationship between the dimensionless discharge time of the raw material and the integrated dimensionless charge amount of the small coke breeze 100 was obtained. The results are shown in FIG.

Next, from FIG. 3, the layer thickness ratio between the O1 batch and the O2 batch was obtained so that the radial distribution of the small coke 100 in the mixed raw material to be charged was uniform. Specifically, the radial distribution of the small coke 100 in the mixed raw material was calculated while changing the layer thickness ratio, and the layer thickness ratio at which the distribution became the most uniform was calculated. The calculation result of the layer thickness ratio is shown in FIG. FIG. 5A shows a predicted value of the radial distribution of the small coke 100 in the mixed raw material when the mixed raw material is charged at the layer thickness ratio shown in FIG.

Next, the mixed raw material is divided into two batches, and the O1 batch (sintered ore 4800 kg, small coke coke 104 kg) and the O2 batch (sintered ore 2600 kg, small coke coke 56 kg) are tilted forward by the swirling chute 4. The mixed layer 202 was formed by charging with.
The charging mass was set to about 1/3 ³ = about 1/27 of the mass assumed in the actual furnace.
The O1 batch was deposited in the range of the furnace opening dimensionless radius of 0.05 to 0.95 by forward tilting, and the O2 batch was deposited in the range of the furnace opening dimensionless radius of 0.4 to 1.0 by forward tilting.
The raw material after charging was sampled at intervals of 20 cm in the circumferential direction and 15 cm in the radial direction, and the radial distribution of the small coke 100 in the mixed raw material was measured.
The results are shown in FIG. 5 (B).

As shown in FIG. 5 (B), the same result as the predicted value shown in FIG. 5 (A) was obtained, and the small coke 100 could be uniformly arranged in the radial direction. Therefore, it was found that the small coke 100 can be uniformly arranged in the radial direction by using the charging method of the bellless blast furnace according to the present embodiment. In the first embodiment, the end of the O2 batch on the furnace center side is set to the position of the furnace opening dimensionless radius 0.4, but the range normally adjusted in the charging method of the bellless blast furnace (the furnace opening dimensionless radius is −0). The same effect can be obtained by changing 1.1 to 0.1). That is, the end of the O2 batch on the center side of the furnace may be in the range of the dimensionless radius of the furnace opening of 0.3 to 0.5.

(Example 2)
In Example 1, the average particle size of the small coke 100 was changed to a smaller size, and the blast furnace charging distribution experiment of the present embodiment was carried out using the same 1/3 scale model experimental device of the same blast furnace as in Example 1. ..

First, sinter as an ore and small coke 100 were prepared as mixed raw materials. The sinter had an average particle diameter of 7.7 mm and a density of 3.3 g / cm ³ . The small coke 100 had an average particle diameter of 9.1 mm and a density of 1.0 g / cm ³ . The particle size ratio of the small coke 100 to the sinter was 1.18, and the density ratio was 0.3.

When this mixed raw material is first put into the swirling chute 4 in the same manner as in Example 1, the raw material is first collected and the ratio of the small coke 100 is measured, and the dimensionless discharge time and the integrated dimensionless coke 100 are accumulated. We asked for the relationship of the charge amount. The results are shown in FIG. As shown in FIG. 7, in Example 2, the dimensionless discharge time was 0.5 and the integrated dimensionless charge amount was 0.4. As shown in FIG. 3, in Example 1, a small coke 100 having a dimensionless discharge time of 0.5 and a cumulative dimensionless charging amount of 0.2 and an average particle size smaller than that of Example 1 is used. In Example 2, it can be seen that the segregation of the small coke 100 is relatively small and is discharged quickly.

Based on FIG. 7, a layer thickness ratio was obtained in the same manner as in Example 1 so that the radial distribution of the small coke 100 in the mixed raw material to be charged was uniform. The calculation result of the layer thickness ratio is shown in FIG. FIG. 9A shows a predicted value of the radial distribution of the small coke 100 in the mixed raw material when the mixed raw material is charged at the layer thickness ratio shown in FIG.

Next, the mixed raw material is divided into two batches, in the order of O1 batch (sintered ore 3600 kg, small coke) and O2 batch (sintered ore 3800 kg, small coke 82 kg) by the swirling chute 4. It was loaded by tilting.
The O1 batch was deposited with a forward tilt in the range of the furnace opening dimensionless radius of 0.05 to 1.0, and the O2 batch was deposited with the forward tilt in the range of the furnace opening dimensionless radius of 0.4 to 1.0.
The raw material after charging was sampled at intervals of 20 cm in the circumferential width and 15 cm in the radial direction, and the radial small coke distribution of the mixed raw material was measured. The results are shown in FIG. 9 (B).

As shown in FIG. 9B, even in Example 2, the small coke 100 could be uniformly arranged in the radial direction. Therefore, it was found that the method for charging the bellless blast furnace according to the present embodiment can uniformly arrange the small coke 100 in the radial direction regardless of the particle size of the small coke 100 to be mixed and charged. In the second embodiment, the end of the O2 batch on the furnace center side is set to the position of the dimensionless radius of the furnace opening of 0.4, but the range normally adjusted in the charging method of the bellless blast furnace (-0 with the dimensionless radius of the furnace opening). The same effect can be obtained by changing 1.1 to 0.1). That is, the end of the O2 batch on the center side of the furnace may be in the range of the dimensionless radius of the furnace opening of 0.3 to 0.5.

(Comparative example)
In Example 1, according to the method described in Patent Document 5, the O1 batch is charged into the range of the furnace opening dimensionless radius 0 to 0.8 by reverse tilting, and the O2 batch is charged with the furnace opening dimensionless radius 0.6 to 1. The charging was performed under the same conditions as in Example 1 except that the charging was performed in the range of 0.0 by reverse tilting. FIG. 10 shows the results of actual measurement of the radial small coke distribution of the mixed raw material.
As shown in FIG. 10, as compared with Example 1 and Example 2, large peaks appeared in the vicinity of the dimensionless radius of 0.3 and the vicinity of 0.8. Therefore, it was found that the small coke 100 was not uniformly arranged in the radial direction.

1 ... surge hopper, 2 ... charging conveyor, 3 ... furnace top hopper, 4 ... swivel chute, 5 ... furnace body shaft part, 6 ... cutting device, 100 ... small coke.

Claims (4)

In the charging method of a bellless blast furnace, a mixed raw material of ore and coke is temporarily stored in the top hopper and charged into the furnace from the top hopper by a swivel chute to form a mixed layer.
The coke has a cumulative dimensionless charge of 0.1 to 0.45 when the dimensionless discharge time of the mixed raw material is 0.5.
When forming the central coke layer, the mixed raw material is deposited by forward tilting from the position of the furnace opening dimensionless radius 0.7 to 1.0 to the position where it overlaps a part or all of the central coke layer.
When the central coke layer is not formed, the first step of depositing the mixed raw material by forward tilting from the position of the furnace opening dimensionless radius 0.7 to 1.0 to the position of the furnace opening dimensionless radius 0 to 0.2. Mixed raw material charging process and
The second mixed raw material charging step of depositing the mixed raw material by forward tilting from the position of the furnace mouth dimensionless radius 0.8 to 1.0 to the position of the furnace mouth dimensionless radius 0.3 to 0.5,
A method of charging a bellless blast furnace, which is characterized by carrying out. The method for charging a bellless blast furnace according to claim 1, wherein the coke is small-lump coke. The first aspect of the present invention is characterized in that, after the second mixed raw material charging step, an ore charging step is carried out in which an ore not mixed with coke is charged onto the mixed layer to form an ore layer. Or the method for charging the bellless blast furnace according to 2. After the second mixed raw material charging step, an ore charging step is carried out in which an ore mixed with coke at a mixing ratio lower than that of the mixed raw material is charged onto the mixed layer to form an ore layer. The method for charging a bellless blast furnace according to claim 1 or 2, wherein the method is to be performed.

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