JP2020015933A - Bell-less blast furnace charge method - Google Patents

Abstract

To provide a charge method, even in the case coke is mixed into ores and the mixture is charged, capable of uniformizing the coke distribution of the ores compared with the conventional case.SOLUTION: A bell-less blast furnace comprises a process where mixed raw material of ores and coke is temporarily stored in a furnace top hopper, and the same is charged into a furnace from the furnace top hopper by a swing chute to form a mixed layer, in which, regarding the mixed raw material, an integrated dimensionless charge amount when the dimensionless exhaust time of the mixed raw material is 0.5 is 0.1 to 0.45, and the charge method includes: a first mixed raw material charge step S1 where the mixed raw material is deposited in forward tilt from a position of 0.7 to 1.0 in a throat dimensionless radius to a position in which the same is overlapped with a part or the whole of a central coke layer in the case the central coke layer is formed and to a position of 0 to 0.2 in a throat dimensionless radius in the case the central coke layer is not formed; and a second mixed raw material charge step S2 where the mixed raw material id deposited in forward tilt from a position of 0.8 to 1.0 in a throat dimensionless radius to a position of 0.3 to 0.5 in a throat dimensionless radius.SELECTED DRAWING: Figure 1

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 in which coke is mixed with ore and charged. This is because coke is harder to soften at the furnace temperature than ore, so that the permeability of the ore layer can be improved. Further, by bringing the coke and the ore close to each other, the reactivity is improved.

  In the method in which coke is mixed and charged into ore, the coke distribution in the mixed layer may be uneven in the furnace radial direction. This is because the coke and the ore have different densities and particle diameters, and therefore, the positions where they are deposited when stored in the furnace hopper are different, and the ore is discharged before the coke. That is, in the furnace top hopper, ores such as sintered ore tend to accumulate near the center and coke tends to accumulate in the periphery. Therefore, when cutting from the furnace top hopper, the sinter just above the discharge port is preferentially discharged by the funnel flow, 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 outlet of the hopper is closed once during the charging of the first batch in which coke is mixed with the ore, the ore of the second batch is charged into the hopper, and the discharging outlet is opened again to charge the ore. A method of discharging coke at the beginning of the second batch by restarting the coke is known (Patent Document 1).

  First, a mixed raw material of ore and coke is charged in a forward tilt, then turned back halfway and charged in a reverse tilt to load a batch of mixed raw material, and the coke distribution in the mixed layer is measured in the furnace radial direction. There is also known a method for making the uniformity (Patent Document 2).

There is also known a method in which a mixed raw material is divided into two batches and a coke mixing amount of the second batch is made larger than that of the first batch (Patent Document 3).
There is also known a method in which a mixed raw material is divided into two batches, a coke mixing amount to the mixed raw material is extremely increased to 60 to 75% by mass, and the second batch is charged into a furnace wall side (Patent Document) 4).
There is also known a method in which a mixed raw material is divided into two batches, and the first batch is charged to the center of the furnace and the second batch is charged to the furnace wall by reverse tilting (Patent Document 5).

Patent No. 6102497 JP-A-2013-134941 Patent No. 4114626 Patent No. 5776866 WO 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 a discharge port of a hopper during charging. There is a problem in such charging with mechanical operation that there is a limit in mechanical structural accuracy and that accurate charging is difficult. There is also a problem that a mechanical failure is likely to occur.

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

  The technique described in Patent Document 3 can prevent coke segregation to some extent, but it is difficult to precisely adjust the coke distribution in the radial direction only by increasing the coke mixing amount of the second batch from that of the first batch. Was.

  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 coke amount per charge is used for the mixed layer.

  According to the technology described in Patent Document 5, although coke segregation to some extent can be prevented, coke distributions in the first batch and the second batch in the radial direction overlap to form a biased distribution having two peaks. Exact adjustment of coke distribution was difficult. Further, since the mixed raw material is charged in reverse tilt, there is 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 is performed. The purpose is to provide a method.

The method for charging a bellless blast furnace according to the present invention comprises charging a bellless blast furnace in which a mixed raw material of ore and coke is temporarily stored in a furnace top hopper and charged into the furnace from a furnace hopper with a swirling chute to form a mixed layer. In the method, when the dimensionless discharge time of the mixed raw material is 0.5, the integrated dimensionless charge is 0.1 to 0.45. When the mixed raw material is deposited by forward tilting from a position having a dimensional radius of 0.7 to 1.0 to a position overlapping part or all of the central coke, and a central coke layer is not formed, a furnace port non-dimensional radius is used. A first mixed material charging step of depositing the mixed material in a forward tilt from a position of 0.7 to 1.0 to a position of a non-dimensional radius of the furnace port of 0 to 0.2; From the position of 8 to 1.0, the furnace opening dimensionless radius 0.3 to 0.5 A second mixed feed charging step of depositing the mixed material in order tilted to a position, which comprises carrying out the.
According to the present invention, the mixed raw material is charged into two batches in which the mixed raw material is charged with a forward tilt from the vicinity of the furnace wall to the vicinity of the furnace center, and the mixed raw material is charged with a forward tilt from the vicinity of the furnace wall to an intermediate portion in the furnace. To enter. Therefore, the coke distribution of the first batch and the second batch does not have two extreme peaks, and coke can be charged uniformly in the radial direction. Further, since both of the two batches are tilted forward, it is easy to adjust the particle size distribution of the ore.

Preferably, the coke is small lump 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 integrated dimensionless charging amount when the dimensionless discharge time is 0.5 is 0.1 to 0.45.
In the present invention, after the second mixed raw material charging step, it is preferable to perform an ore charging step of charging an ore that does not mix coke on the mixed layer to form an ore layer.
In the present invention, after the second mixed raw material charging step, the ore obtained by mixing coke at a lower mixing ratio than the mixed raw material is charged on the mixed layer to form an ore layer. Preferably, an ore charging step is performed.
According to the present invention, the coke is not mixed or the ore layer having a low coke mixing ratio is formed on the mixed layer, so that the coke in the mixed layer hardly comes 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 coke mixing can be further enhanced, and more stable operation with a high reduction rate can be realized.

The flow figure showing the outline of the charging method of the bell-less blast furnace concerning this embodiment. It is sectional drawing which shows the mixed raw material charged when central coke is not charged by the charging method of the bellless blast furnace which concerns on this embodiment, (A) is O1 batch charging, (B) is O2. (C) is a diagram showing the state after charging the O3 batch after charging the batch. FIG. 4 is a diagram illustrating a relationship between a dimensionless discharge time of a mixed raw material charged and an integrated dimensionless charged amount of coke in the first embodiment. FIG. 4 is a diagram showing a layer thickness ratio between an O1 batch and an O2 batch in Example 1. In Example 1, it is a figure which shows the relationship between the non-dimensional radius of a furnace port and the dimensionless amount of coke deposition of a mixed layer, (A) is a predicted value, (B) is an experimental value. The figure which shows the model experiment apparatus used in the Example. In Example 2, the figure which shows the relationship between the dimensionless discharge time of the mixed raw material charged and the integrated dimensionless charging amount of coke in the mixed layer. FIG. 9 is a diagram showing a layer thickness ratio between an O1 batch and an O2 batch in Example 2. In Example 2, it is a figure which shows the relationship between the non-dimensional radius of a furnace port and the dimensionless amount of coke deposited in a mixed layer, (A) shows a predicted value and (B) shows an experimental value. The figure which shows the relationship between the non-dimensional radius of a furnace opening and the non-dimensional deposition amount of coke in a mixed layer in a comparative example.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
First, an overview of a method for charging a bellless blast furnace according to the present embodiment will be described with reference to FIG.

  First, when forming a central coke layer from the position of the furnace port dimensionless radius of 0.7 to 1.0, the mixed raw material is deposited by forward tilting to a position overlapping 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 non-dimensional radius of the furnace port 0.7 to 1.0 to the position of the non-dimensional radius of the furnace port 0 to 0.2 (see FIG. 1). S1, first mixed raw material charging step).

  Next, the mixed raw material is 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. 2 mixed material charging step).

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

Next, details of the method for charging the bellless blast furnace according to the present embodiment will be described.
<Target blast furnace>
In the charging method according to the present embodiment, the structure and dimensions of the target blast furnace are not particularly limited as long as the blast furnace is a bellless blast furnace. A bellless blast furnace refers to a blast furnace having a bellless charging device.
The charging method according to the present embodiment is limited to a case where the mixed raw material is temporarily stored in a furnace top hopper, and is charged into the furnace from the furnace top hopper by a rotating chute to form a mixed layer. When the mixed raw materials are not temporarily stored in the furnace hopper, that is, when the ore and coke stored in separate hoppers are simultaneously cut into the furnace and charged into the furnace, the influence of the segregation in the furnace hopper described above. This is because the timing of charging coke into the blast furnace can be arbitrarily controlled, and the problem of uneven distribution of coke in the mixed layer in the furnace radial direction does not occur.
The operating conditions are not particularly limited except that a mixed raw material of ore and coke is charged.

The type of coke is not particularly limited. Normal lump coke can be used. However, when the dimensionless discharge time of the mixed raw material is 0.5, the integrated dimensionless charge amount needs to be 0.1 to 0.45. If it exceeds 0.45, coke does not segregate even if this embodiment is not performed. If it is less than 0.1 range, coke will not be uniformly distributed even if the charging method of the present embodiment is used. More preferably, when the dimensionless discharge time of the mixed raw material is 0.5, the integrated dimensionless charge is 0.2 to 0.4.
As such coke, small lump coke is preferable. The small lump coke referred to here is a sieve under a coke 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. The ore is a general term for iron-containing raw materials charged into a blast furnace, and refers to sinter, lump ore, pellets, coal-bearing agglomerates, and mixtures thereof.
The number of batches for one charge and the ore and coke particle sizes are not limited except for the requirements specified in S1 to S3. The mixing ratio is not particularly limited. The tapping ratio is not particularly limited.
The particle size and charging conditions of the coke forming the coke layer are not particularly limited. Central coke may or may not be charged.

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

<S1: First mixed raw material charging step>
In S1, when the central coke is not charged, as shown in FIG. 2A, the position of the non-dimensional radius of the furnace port is 0.7 to 1.0, and the position of the non-dimensional radius of the furnace port is 0 to 0.2. Until P1, a part of the mixed raw material forming the mixed layer 202 is charged by forward tilting. When charging the central coke, a part of the mixed raw material constituting the mixed layer 202 is transferred from the position of the furnace opening dimensionless radius 0.7 to 1.0 to the position P1 overlapping 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 non-dimensional radius of the furnace port is as follows: 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 radial position P in the furnace radial direction is r, the position P is r / R. These values are shown (see FIGS. 2A and 2B).

<S2: second mixed raw material charging step>
In S2, from the position of the furnace port non-dimensional radius 0.8 to 1.0 to the position of the furnace port non-dimensional radius 0.3 to 0.5, the mixed material constituting the mixed layer 202 is charged in S1. The remaining material is charged by forward tilting (S2 in FIG. 1, second mixed material charging step).
Here, the mixed raw material charged in S2 is referred to as an O2 batch.
FIG. 2B shows the charge distribution of the mixed raw material in the blast furnace after the completion of S2.

Due to the execution of S1, the O1 batch is charged in substantially the entire region where the mixed layer 202 is to be formed. However, since the ore is discharged before the small coke 100 at the time of charging, the small coke 100 is segregated at the furnace center side, 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 within a range of the furnace port non-dimensional radius 0.3 to 0.5 from the position 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 small coke amount in the mixed layer 202 on the furnace wall side of the O1 batch and the O2 batch and the small coke amount in the mixed layer 202 on the furnace center side of only the O1 batch becomes small, Uneven distribution of the small coke 100 can be suppressed. 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 opening dimensionless radius 0.3 to 0.5 will be described in detail in Examples.
In addition, since both the O1 batch and the O2 batch are charged in a forward tilt, the particle size distribution of the ore can be easily adjusted.

  The layer thickness ratio between the O1 batch and the O2 batch is determined based on the density difference between the ore and the small coke 100 and the material discharge characteristics from the furnace top hopper 3 due to the difference in particle diameter. What is necessary is just to set suitably so that the radial distribution of 100 may be homogenized 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 on the surface of the mixed layer 202 in FIG. 2B is set. Since the mass ratio (O / C) of the coke layer and the ore layer is determined in advance as operating conditions, the layer thickness of the mixed layer 202 is determined by the relationship with 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 charged amount of small coke in the mixed raw material is determined. The relationship between the dimensionless discharge time of the mixed raw material and the integrated dimensionless charged amount of the small coke in the mixed raw material may be obtained by a test device, or may be obtained from a sampling test during a cold wind or past operation results. For example, Discrete Element Method (DEM), "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. 175-175) 182) 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 defined as T, which is the time required until the discharge of the mixed raw material is completed, and t, which is an arbitrary time elapsed after the discharge of the mixed raw material is started. It is represented by t / T.

The integrated dimensionless charged amount of the small coke refers to the charged amount (mass) of the small coke in the mixed raw material at the time of completion of the discharge of the mixed raw material as M, and the small dimension at the dimensionless discharge time t / T. When the accumulated charge (mass) of the lump coke is m, the accumulated charge of the small lump coke is represented by m / M. When determining the relationship between the dimensionless discharge time of the mixed raw material and the integrated dimensionless charged 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. The mass of all the obtained small coke may be M, and the mass of the integrated small coke sampled up to a certain point corresponding to the dimensionless discharge time t / T may be m.
FIG. 3 shows an example of the relationship between the obtained dimensionless discharge time of the mixed raw material and the integrated dimensionless charged amount of the small coke in the mixed raw material.

  Next, the layer thickness ratio is determined such that the small coke distribution in the radial direction of the mixed raw material to be charged is as uniform as possible. For example, the small coke distribution in the radial direction 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 operation of changing the layer thickness ratio includes changing the charging range of each of the O1 batch and the O2 batch.

  FIG. 4 shows an example of the layer thickness ratio. FIG. 5A shows the result of calculating the small coke distribution in the radial direction of the mixed raw material at the layer thickness ratio shown in FIG. In FIG. 5A, the small coke distribution is shown by the relationship between the non-dimensional radius of the furnace port and the non-dimensional deposition amount. The dimensionless deposition amount is a ratio of the deposition amount (volume) of the small coke 100 when the deposition 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 between the O1 batch and the O2 batch, the charged amount of the mixed raw material in the O1 batch and the O2 batch is determined. In the above description, the distribution of the small coke 100 to each batch is set in advance. However, the distribution of the small coke 100 to each batch is more uniform so that the radial distribution of the small coke 100 in the mixed layer becomes more uniform. 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 performed as necessary (see FIG. 2C). Here, the ore charged in S3 is referred to as an O3 batch.

No coke is mixed into the O3 batch, or coke is mixed at a lower mixing ratio than the O1 batch and the O2 batch. The mixing ratio is obtained as a mass ratio of the mass of coke to the mass of the ore raw material similarly for the small coke 100 and other coke.
By forming the ore layer 203 on the mixed layer 202, the coke layer 201 of the next charge is not formed immediately above the mixed layer 202, so that the small coke 100 in the mixed layer 202 is separated from 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 operation at a high reduction rate can be achieved. 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).
Although the particle size of the ore in the O3 batch is not particularly specified, it is preferably the same as the particle size of the ore in the O1 batch and the O2 batch.
The above is the detailed description of the method for charging the bellless blast furnace according to the present embodiment.

  Thus, 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 the mixed raw material is charged in a forward tilting manner from the vicinity of the furnace wall to an intermediate portion in the furnace. The charging is performed separately in the step (S2). Therefore, the small coke distribution in the furnace diameter direction in the mixed layer 202 in which the O1 batch and the O2 batch are combined does not have two extreme peaks, and the small coke can be charged uniformly in the furnace diameter direction. Further, since both the O1 batch and the O2 batch are tilted forward, 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 the examples.

(Example 1)
A blast furnace charging distribution experiment of the present embodiment was performed using a 1/3 scale model experiment apparatus for a blast furnace. The specific procedure is as follows.
First, a model experiment apparatus 11 shown in FIG. 6 was prepared as an experiment apparatus.

  The model experiment device 11 is a charged material charging device and a 1/3 model of the upper part of the blast furnace main body, and includes a surge hopper 1, a charging conveyor 2, a furnace top hopper 3, a turning chute 4, a furnace body shaft portion 5, And a cutting-out device 6.

The surge hopper 1 is a storage for storing charged coke and ore.
The charging conveyor 2 is a conveyor that conveys the charging material cut out from the surge hopper 1 to the furnace top hopper 3. The furnace top hopper 3 is a hopper for temporarily storing the raw material immediately before charging. The revolving 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 the shaft portion of the blast furnace. The cutout device 6 is provided at the lower end of the furnace body shaft portion 5 and cuts out the charged raw material to reproduce the unloading in the furnace.

Next, sintered ore as 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 an actual furnace. The sintered ore had an average particle size of 7.7 mm and a density of 3.3 g / cm ³ . The small lump 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 sintered ore was 1.40, and the density ratio was 0.3.

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

  Next, from FIG. 3, the layer thickness ratio between the O1 batch and the O2 batch was determined 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. FIG. 4 shows the calculation results of the layer thickness ratio. 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 was divided into two batches, and the O1 batch (sinter 4800 kg, small coke 104 kg) and the O2 batch (sinter 2600 kg, small coke 56 kg) were sequentially tilted by the turning chute 4 in this order. To form a mixed layer 202.
The charged mass was set to about 1/3 ³ = about 1/27 of the mass assumed in the actual furnace.
The O1 batch was deposited by forward tilting in the range of 0.05 to 0.95 in the furnace opening non-dimensional radius, and the O2 batch was deposited by forward tilting in the range of the non-dimensional radius of the furnace opening of 0.4 to 1.0.
The charged raw material was sampled at a width of 20 cm in the circumferential direction and at 15 cm intervals in the radial direction, and the radial distribution of the small coke 100 in the mixed raw material was actually measured.
The results are shown in FIG.

  As shown in FIG. 5B, a result similar to the predicted value shown in FIG. 5A 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 bellless blast furnace charging method according to the present embodiment. In Example 1, the furnace center side end of the O2 batch was set to the position of the non-dimensional radius of the furnace port of 0.4. However, the range normally adjusted in the charging method of the bellless blast furnace (−0 in the non-dimensional radius of the furnace port). .1 to 0.1), the same effect can be obtained. That is, the furnace center side end portion of the O2 batch may be in the range of 0.3 to 0.5 of the furnace opening dimensionless radius.

(Example 2)
In Example 1, the average particle diameter of the small lump coke 100 was changed to be smaller, and the blast furnace charging distribution experiment of the present embodiment was performed using the same 1/3 scale model experiment apparatus of the blast furnace as in Example 1. .

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

  As in Example 1, the mixed raw material was first introduced into the revolving chute 4, the raw material was collected and the proportion of the small coke 100 was measured. The relationship between the charging amounts was determined. FIG. 7 shows the results. As shown in FIG. 7, in Example 2, the dimensionless discharge time was 0.5 and the integrated dimensionless charge was 0.4. As shown in FIG. 3, Example 1 uses small coke 100 having a dimensionless discharge time of 0.5, an integrated dimensionless charge of 0.2, and a smaller average particle diameter than that of Example 1. In Example 2, it can be seen that segregation of the small lump coke 100 is relatively small and is discharged quickly.

  Based on FIG. 7, the layer thickness ratio such that the radial distribution of the small coke 100 in the mixed raw material to be charged becomes uniform was determined in the same manner as in Example 1. FIG. 8 shows the calculation result of the layer thickness ratio. 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, and the O1 batch (3600 kg of sintered ore, 78 kg of small lump coke) and the O2 batch (3800 kg of sintered ore, 82 kg of small lump coke) are sequentially turned by the rotating chute 4 in order. It was charged by tilting.
The O1 batch was deposited with a forward tilt in the range of the furnace port non-dimensional radius 0.05 to 1.0, and the O2 batch was deposited with the forward tilt in the range of the furnace port non-dimensional radius 0.4 to 1.0.
The charged raw material was sampled at intervals of 15 cm in the circumferential direction with a width of 20 cm in the circumferential direction, and the small coke distribution in the radial direction of the mixed raw material was actually measured. The results are shown in FIG.

  As shown in FIG. 9B, also in Example 2, the small coke 100 could be uniformly arranged in the radial direction. Therefore, it was found that the charging method of the bellless blast furnace according to the present embodiment can uniformly arrange the small coke 100 in the radial direction regardless of the particle diameter of the small coke 100 to be mixed and charged. In Example 2, the furnace center side end of the O2 batch was set to the position of the non-dimensional radius of the furnace port of 0.4. .1 to 0.1), the same effect can be obtained. That is, the furnace center end of the O2 batch may be in the range of 0.3 to 0.5 in the non-dimensional radius of the furnace port.

(Comparative example)
In Example 1, according to the method described in Patent Document 5, the O1 batch was charged in the range of 0 to 0.8 in the furnace port non-dimensional radius by reverse tilting, and the O2 batch was 0.6 to 1 in the furnace port non-dimensional radius. 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 measurement results of the small coke distribution in the radial direction of the mixed raw material.
As shown in FIG. 10, as compared with Example 1 and Example 2, large peaks appeared near the dimensionless radius 0.3 and around 0.8. Therefore, it turned out that the small lump coke 100 is not arranged uniformly in the radial direction.

  DESCRIPTION OF SYMBOLS 1 ... Surge hopper, 2 ... Loading conveyor, 3 ... Furnace top hopper, 4 ... Revolving chute, 5 ... Furnace shaft part, 6 ... Cutting device, 100 ... Small coke.

Claims (4)

In a method of charging a bellless blast furnace in which a mixed raw material of ore and coke is temporarily stored in a furnace top hopper and charged into the furnace with a swirling chute from the furnace hopper to form a mixed layer,
The coke has an integrated 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, from the position of the furnace port non-dimensional radius 0.7 to 1.0, to the position overlapping with part or all of the central coke layer, the mixed raw material is deposited by forward tilting,
When the central coke layer is not formed, the first mixed material is deposited by forward tilting from the position of the non-dimensional radius of the furnace port 0.7 to 1.0 to the position of the non-dimensional radius of the furnace port 0 to 0.2. Mixed raw material charging process,
A second mixed raw material charging step of depositing the mixed raw material in a forward tilt from a position of the furnace opening dimensionless radius 0.8 to 1.0 to a position of the furnace opening dimensionless radius 0.3 to 0.5,
A method for charging a bellless blast furnace.   The method for charging a bellless blast furnace according to claim 1, wherein the coke is small lump coke.   The ore charging step, wherein an ore in which coke is not mixed is charged on the mixed layer to form an ore layer after the second mixed raw material charging step. Or the method of charging a bellless blast furnace according to 2.   After the second mixed raw material charging step, an ore in which coke is mixed at a lower mixing ratio than the mixed raw material is charged on the mixed layer to form an ore layer. The method for charging a bellless blast furnace according to claim 1, wherein the method is performed.

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