JP2822861B2 - Blast furnace operation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating a blast furnace in which charging of coke alone and charging of ore and coke are repeated, and more particularly, the particle size ratio of ore and coke charged simultaneously, and charging. The ore / coke weight ratio at the center of the blast furnace (ore / co
ke (hereinafter referred to as O / C ratio) at a low level to secure the gas permeability and liquid permeability of the blast furnace core and the appropriate gas flow rate in the center of the furnace to maintain a stable furnace condition. To a blast furnace operating method that can be used.

[0002]

2. Description of the Related Art In order to operate a blast furnace stably and efficiently, it is important to appropriately control a gas flow distribution rising in the furnace. The ore is gradually heated and reduced by the action of the high-temperature reducing gas (CO, H ₂ ) generated by the reaction between the hot air blown from the tuyeres installed at the lower part of the furnace and the coke, and softens as it descends. After forming the cohesive zone, it becomes hot metal.

[0003] The hot metal accumulates at the furnace bottom along the gap between the core coke layers and is intermittently or continuously extracted from the tap hole. It has been empirically known that it is effective to centralize the blast furnace ascending gas in order to enhance the efficiency and stability of such blast furnace operation.

[0004] Many proposals have been made on a raw material charging distribution control method for appropriately securing the rising gas in the center of the blast furnace. For example, in Japanese Patent Publication No. 64-9373,
A method has been proposed in which a dedicated charging route is provided to charge a portion of coke into the center of the blast furnace, thereby increasing the coke abundance ratio with respect to the ore in the center and increasing the central flow. According to this method, the central flow is strengthened while maintaining a good cohesive zone shape and gas utilization rate.Therefore, effects such as stabilization of blast furnace operation, reduction of molten iron Si, and reduction of furnace wall heat load are obtained. It is shown in that publication.

Japanese Patent Laid-Open Publication No. 4-63212 discloses a method of alternately charging a mixture in which a part of the whole coke is mixed in an ore and the remaining coke into a blast furnace. By increasing the particle size of the mixed coke according to the coke weight fraction, utilizing the characteristic that coke is unevenly distributed in the center of the blast furnace and near the furnace wall when a mixed layer of ore and coke is deposited in the furnace A method for securing a gas flow in a central portion is disclosed. According to this method, it is said that stabilization of tapping slag, reduction of furnace pressure loss, and reduction of fluctuations in the Si concentration in the hot metal are achieved.

On the other hand, the coke particle size in a mixed layer of coke and ore, which is a part of the charged coke amount, is reduced to 1.4% of the ore particle size.
~ 9.0 times, the mixed coke supports the load of the upper charge, and avoids the close contact between reduced iron and coke in the softening cohesive zone, thereby avoiding carburization of reduced iron, Japanese Patent Application Laid-Open No. S61-153211 discloses a method for producing low-Si hot metal by suppressing the transfer of Si to reduced iron.

However, each of the above methods has the following problems. In other words, in the method disclosed in Japanese Patent Publication No. 64-9373, it is necessary to provide a charging device dedicated to coke in the upper space of the charge accumulation level at the furnace top in order to charge coke into the center of the furnace. is there. However, in the case of this charging method, the maintenance of the apparatus may be hindered because the central part of the furnace top is always exposed to a high temperature rising gas. Furthermore, at the time of high tapping operation, since the number of times of charging increases and the time required for one charging is limited, the number of times of charging from another system is added to the number of times of normal charging. However, it is also conceivable that this could hinder the smooth operation of high tapping.

Japanese Patent Application Laid-Open No. 4-63212 discloses that the average particle size dp (mm) of 20% by weight of the coke to be mixed with the ore is changed to the charging amount W (% by weight) of the coke mixed into the ore. ), It is shown to be (W + 20) mm or more. However, in order to control the abundance ratio of coke and ore in the radial direction by utilizing the uneven distribution phenomenon in the coke deposition process of coke mixed ore layer, the particle size between coke and ore particles, which greatly affects the uneven distribution amount, It is necessary to define the ratio and the density ratio. Since the latter is usually a constant value, it is important to determine the particle size ratio of the ore and the coke mixed with the ore. However, in the method disclosed in this publication, since the particle size ratio of coke and ore is not taken into account, the controllability of the uneven distribution amount of coke and ore determined by the density ratio between particles and the particle size ratio is not necessarily good. However, it is necessary to further improve the controllability of the coke abundance distribution in the blast furnace radial direction with respect to securing the rising gas in the center of the blast furnace in order to improve the efficiency and stabilization of blast furnace operation.

On the other hand, according to the method disclosed in Japanese Patent Application Laid-Open No. Sho 61-153211, if the ratio between the coke particle size and the ore particle size in the coke mixed ore layer is properly defined, low Si hot metal is produced. However, in this method, coke is present in the softened cohesive zone to support the load of the upper charge and to avoid close contact between reduced iron and coke. In the mixed ore layer, the mixed coke needs to be uniformly present in the blast furnace radial direction.
That is, this method is not a method intended to control the distribution of coke abundance in the blast furnace radial direction in which coke is unevenly distributed in the center of the blast furnace.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a blast furnace operation in which coke is charged alone and ore and coke are charged simultaneously. By controlling the O / C ratio of
In addition to ensuring the amount of gas rising in the center of the blast furnace, reducing the reaction amount of coke supplied to the center of the blast furnace, ensuring the particle size and strength of the furnace core coke, and improving the permeability and liquid permeability of the blast furnace core And a blast furnace operating method capable of maintaining the furnace condition stably.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a blast furnace operation in which charging of coke alone and charging of ore and coke are repeated in a blast furnace operation. The particle size ratio and the charging amount ratio, and if necessary, the charging pattern is optimized, and the above-mentioned object is achieved by utilizing the classification deposition of the mixed raw material particles when the blast furnace is charged. The summary is (1) and (2) below.
Blast furnace operation method.

(1) When operating a blast furnace by repeatedly charging coke alone and charging ore and coke simultaneously, the weight ratio weighted average particle size of coke charged simultaneously with the ore is determined by determining the particle size of the ore. A method for operating a blast furnace, wherein the bulk volume ore occupying 10% by volume of the total ore is at least 2.5 times the weighted average particle size of the coarse ore.

(2) When operating the blast furnace by repeatedly charging the coke alone and charging the ore and coke simultaneously, the weight percentage weighted average particle size of the coke charged simultaneously with the ore is determined by the particle size of the ore. From the coarser one, the bulk volume ratio of the coarse ore occupying 10% by volume of the total ore shall be 2.5 times or more the weighted average particle size, and the amount of the ore charged at the same time (bulk volume%,
A method for operating a blast furnace, wherein the relationship with the amount of coke (bulk volume%, Y) is adjusted so as to satisfy the following expression as in X).

Y ≦ 0.2 × X In the method of the present invention, when the ore and a part of coke charged in the coke are simultaneously charged into the furnace, the ore and the coke are mixed from the small bell to the large bell. The coke and the ore may be separately discharged from the small bell into the large bell storage sequentially, and then into the furnace from the large bell. Coke and ore may be charged simultaneously. However, at the bottom of the reservoir between the Great Bell Cup and the Great Bell, coke was first deposited, and ore was deposited on top of it. Is more preferable. Such a charging pattern is also included in one form of simultaneous charging of ore and coke.

[0015]

The operation of the present invention will be described below based on the results of a charging experiment of a blast furnace model and the simulation results of a mixed raw material uneven distribution prediction model according to the probability theory.

FIG. 1 shows the actual blast furnace (internal volume) used in the charging experiment.
1850m ³ ) 1/7 scale blast furnace top half cut model
(A) is a three-dimensional perspective view, (b) is a half cut vertical sectional view.

The raw material in the ore storage portion between the bell cup 3 and the bell 2 shown in FIG. 1 is discharged by descending the bell 2 and colliding with the armor 5, and after the collision, the coke layer for several charges charged into the furnace. 6 and an ore layer or a coke mixed ore layer 7 are laminated. With such raw material charging, the radial distribution of the weight ratio of ore to coke after being deposited in the furnace (hereinafter referred to as the deposited O / C ratio) was measured.

The apparent densities of the ore (particle size is D _O ) and coke (particle size is D _C ) used in the charging experiment are as follows:
Each 3.2 g / cm ^3, a 1.08 g / cm ^3, co-charging coke amount was 2.7% certain ore weight. Simultaneous charging of ore and coke consists of a pattern in which a mixed raw material of coke and ore (hereinafter simply referred to as mixed raw material) is charged into the furnace from bell 2 (hereinafter referred to as mixed raw material charging), First, coke was deposited on the bottom of the furnace, and coke was charged into the furnace from bell 3 in preference to the ore deposited on the top of the coke (hereinafter referred to as preferential charging of coke). The experimental conditions are shown in A and B below.

Experiment A: D _O / D _C ... 0.6, 1.0, 1.2, and 1.6 Charge pattern: Raw material mixed charge Experiment B: D _O / D _C .0.4 Charge pattern: Raw material mixed charge or coke preferential charge FIG. 2 shows the relationship between the state of uneven distribution of the raw material in the blast furnace radial direction and the particle size ratio between ore and coke (hereinafter, referred to as D _O / D _C ).
The charged O / C ratio is the O / C ratio when the charged ore and coke are deposited in the furnace in a state of being uniformly mixed without uneven distribution.
/ C ratio. Therefore, the (deposition O / C
When the value of (ratio) / (charge O / C ratio) is 1, it indicates that there is no uneven distribution of raw materials, and when it exceeds 1, it indicates that there is uneven distribution of ore, and when it is less than 1, it indicates that there is uneven distribution of coke.

As shown in the figure, by making D _O / D _C smaller than 1.2, the dimensionless distance from the furnace center (the amount obtained by dividing the actual distance by the inner radius of the furnace to make it dimensionless) is about 0.3. Coke can be unevenly distributed in the area on the furnace center side (hereinafter referred to as the furnace center area), and the dimensionless distance is 0.3 to 0.
Ore can be unevenly distributed in the furnace middle area of No. 8. The degree of these uneven distribution increases as D _O / D _C decreases.

On the other hand, when D _O / D _C is 1.6, ore is unevenly distributed in the furnace central region, and coke is unevenly distributed in the region near the furnace wall with a dimensionless distance of 0.8 or more. When D _O / D _C was 1.2, uneven distribution of the raw material was hardly observed.

FIG. 3 shows the influence of the charging pattern on the uneven distribution of the raw material in the radial direction of the blast furnace. As shown, D _O /
Since D _C is lower than 0.4 and FIG 2, the degree of uneven distribution of ore to uneven distribution Oyohi furnace intermediate region of the coke into the furnace center region is made stronger than that of FIG. It is apparent that the coke preferential charging can increase the coke uneven distribution in the furnace central region as compared with the raw material mixed charging.

The mechanism in which the above-described uneven distribution of raw materials occurs in the sedimentary layer after the ore and the coke having the density difference and the particle size difference are simultaneously charged and deposited in the furnace is considered as follows.

FIGS. 4A and 4B are conceptual diagrams for explaining the classifying and depositing action in the process of depositing mixed particles having a difference in particle size and density in a furnace. FIG. Is the case where there is a density difference.

As shown in FIG. 4A, when particles having different particle sizes flow down a slope in a mixed state, particles A having a small particle size pass through gaps between particles B having a large particle size. Move to lower level. At this time, the probability that the particles A pass through the gaps between the particles B is proportional to the size of the gaps between the particles B with respect to the particles A and the frequency at which the particles A encounter the gaps of the particles B while flowing down the slope. Is, the larger the particle size difference between the particles A and B,
The latter is larger as the velocity gradient in the direction perpendicular to the slope of the mixed particles flowing down is larger, and classification based on the particle size difference is actively performed. Therefore, particles A having a small particle size undergo classification in the vicinity of the drop point and accumulate near the furnace wall upstream of the slope, and particles B having a large particle size float near the drop point and are transported downstream of the slope. It will be unevenly distributed in the center.

On the other hand, as shown in FIG. 4 (b), when particles having different densities flow down the slope in a mixed state, compared with the collision of particles having the same density among the particles flowing down. ,
Since the low-density particles B have a large recoil when colliding with the high-density particles A, coarse voids are formed by the particles B in the vicinity of the high-density particles A. The probability of passing and moving to the lower layer increases. Therefore, high-density particles A are subjected to classification near the drop point and accumulate near the furnace wall upstream of the slope, and low-density particles B float near the drop point and are transported downstream of the slope. Will be unevenly distributed.

The present inventor has considered that the above-described uneven distribution of the raw material in the mixed raw material deposition layer is determined by the probability that the mixed raw material particles flowing down the slope are classified and deposited in the deposition process.

It is considered that this probability varies depending on the density ratio of the mixed particles, the particle size ratio in consideration of the particle size distribution, the charging ratio, the charging speed, and the charging pattern. Then, the probability of classification and sedimentation was quantified based on the measured raw material uneven distribution values in the charging model experiment with these changed, and a mixed raw material uneven distribution prediction model in the radial direction of the sedimentary layer was created. The calculated values of the mixed raw material uneven distribution prediction model are also shown in FIGS. 2 and 3, but the measured values and the calculated values are almost the same, and it is possible to simulate the radial distribution of the deposited O / C ratio of the actual blast furnace. I understood.

Using the above mixed raw material uneven distribution prediction model, a numerical simulation was conducted for an actual blast furnace (internal volume: 2700 m ³ , air flow: 4400 Nm ³ / min). Tables 1 and 2 show the charging conditions and raw material particle size conditions of the actual blast furnace. FIG. 5 shows the particle size distribution of the charged raw material.
(B) is coke, and the particle size conditions are as shown in Tables 1 and 2.

[0030]

[Table 1]

[0031]

[Table 2]

FIG. 6 is a diagram showing the distribution of the deposited O / C ratio in the radial direction of the blast furnace in each case of Tables 1 and 2 in comparison.
(A) when no removable armor is used, (b)
Indicates the case where movable armor is used.

In Cases 1 and 5, ordinary ore charging without coke mixing was performed, and in other cases, coke and ore charging were performed simultaneously. Cases 2 and 3 without removable armor
Is the mixed bulk volume fraction of co-charged coke to ore
(Hereinafter referred to as Y / X. However, X bulk volume% of simultaneous charging ore, Y is bulk volume percent of coke) as a 0.15 constant, the weight ratio weighted average particle size of the coke (hereinafter, D _C and denoted simply mixing coke say average particle diameter), the bulk volume ratio weighted mean particle size of the coarse particle ore respectively occupy ore coarse side 10 bulk volume% (hereinafter, denoted as crude D _O, simply coarse ore average 2.2 times and 2.6 times the particle size).

In Case 4, coke having the same particle size and particle size distribution as Case 3 (Coke A _{0 in} FIG. 5B) was used, and the coke mixed bulk volume ratio Y / X was increased to 0.22.
In cases 6 and 7 using the movable armor, the coke mixed bulk volume ratio Y / X was fixed at 0.10, and the mixed coke average particle diameter D _C was set to the coarse ore average particle diameter D _O.
2.2 times and 2.5 times.

Case 8 was the same as Case 7 except that the coke charging pattern was changed to coke priority charging. Except for Case 8, the simultaneous charging pattern was a raw material mixed charging.

As shown in FIG. 6, in the case where coke was mixed in the ore layer, the area from the middle of the furnace to the vicinity of the furnace wall was smaller than in cases 1 and 5 (conventional method) in which coke was not mixed in the ore layer. The deposition O / C ratio at the center of the furnace is slightly higher, and the deposition O / C ratio in the furnace center region is lower. Then, 4 and casing 3 in which the D _C 2.6 times a coarse D _O is, D _C
There than 2.2 times of the case 2 of the crude D _O, The case 7 in which the D _C 2.5 times a coarse D _O is, D _C is compared to 2.2 times the casing 6 of the crude D _O, furnace center region Is controlled to a low level. This is because, by setting the average particle size of the mixed coke to be at least 2.5 times the average particle size of the coarse ore, classification and deposition of coarse ore in the in-furnace deposition process was promoted, and coke was unevenly distributed in the central region of the furnace. Therefore, the ore abundance in the furnace center area is low, and the CO ₂ generated by ore reduction
The amount of generated gas and H ₂ O gas can be suppressed to a low level. For this reason, the reaction deterioration of the coke due to CO ₂ and H ₂ O gas and the resulting powdering of the coke are suppressed, and the air permeability and liquid permeability of the core coke are maintained well.

Further, in case 4 (Y / X = 0.22),
Compared to Case 3 (Y / X = 0.15), the furnace center region having a lower deposition O / C ratio is expanded in the radial direction. On the other hand, when the simultaneous charging coke amount becomes a certain amount or more, the single charging coke amount decreases and the layer height of the single charging coke layer decreases, so that the deposition O / C ratio in the furnace middle region and the furnace wall vicinity region. Will be higher. For this reason, a desirable reduction gas flow velocity distribution in the blast furnace radial direction cannot be obtained, and the reaction efficiency of the blast furnace may be reduced.

Further, according to the reaction analysis in the blast furnace, the deposition O /
It has been found that it is important to control the C ratio to a low level.

Accordingly, the average coke particle size is set to be at least 2.5 times the average particle size of the coarse ore, and the coke mixed bulk volume ratio is increased.
By setting it to 0.2 or less, most of the co-charged coke can be unevenly distributed in the furnace center area within 0.2 at a dimensionless distance from the furnace center axis, and without reducing the reaction efficiency of the blast furnace,
The deposition O / C ratio in the furnace central region can be controlled to a low level.

By the way, the particle size ratio is compared with the average mixed coke particle size and the average particle size of coarse ore occupying 10% by volume on the coarse side of the ore coarse particle, and the amount of coke charged at the same time is calculated by the coke mixed bulk volume ratio. The reasons are shown below. That is, in ore charging alone, coarse ore accumulates in the furnace center region due to uneven distribution of the particle size of the ore itself. Then, when the ore and coke are charged at the same time, the coarse ore is classified and deposited in the furnace deposition process, and coke is unevenly distributed in the furnace central region. It is necessary to select the particle size. Also, in order to control the radial region from the furnace center axis to replace the coarse ore unevenly distributed in the furnace center region with the coke and the ore simultaneously by the coke unevenly distributed in the furnace center region by ore alone charging, If the weight fraction specifies the bulk density, the replacement of coarse ore and co-charge coke becomes inaccurate. Therefore, it is necessary to define the amount of co-charged coke charged by the bulk volume fraction ratio to the ore.

Further, in case 8 in which the simultaneous charging pattern is coke priority charging, the deposition O / C ratio in the furnace central region can be controlled lower than in case 7 in which the raw material mixture charging is performed. This means that by performing preferential charging of coke, the amount of ore in co-charged coke in the initial stage of charging can be reduced, and therefore, the probability of ore being classified and deposited in the in-furnace deposition process increases, This is because coke is unevenly distributed to the central region.

Hereinafter, the effects of the present invention will be specifically described with reference to examples.

[0043]

Using EXAMPLES furnace volume 2700 m ³ of the blast furnace, it is charged alternately and coke alone and coke mixed ore with operation of the examples and comparative examples, alternately singly and coke and ore respectively the operation of the prior art Was charged. The air volume is 4400Nm ³ / min,
The raw material charging conditions and the raw material particle size conditions are as shown in Tables 1 and 2 above.

Table 3 (with no movable armor) and Table 4 (with movable armor) show the main charging conditions and raw material particle size conditions of Examples, Comparative Examples and Conventional Examples.
The conditions in the furnace during operation, that is, the blowing pressure, the number of slips, the fluctuation rate of the Si concentration in the hot metal, the measured value of the weighted average particle size of the core coke by the tuyere coke sample, and the fluctuation amount of the hot metal temperature were shown. FIGS. 7 and 8 show the furnace top gas temperature distribution and CO2 measured in the furnace top at the furnace top without using the movable armor, respectively.
The gas utilization rate distribution (= CO ₂ volume% / (CO + CO ₂ ) volume%) is shown.

[0045]

[Table 3]

[0046]

[Table 4]

[0047] As shown in Table 3, 4 and 7 and 8, is performed simultaneously charging ore and coke, 2.2 times the mixing coke average particle diameter D _C is the coarse particle ore average particle径粗D _O In Comparative Examples 1 and 2, the increase in the furnace top gas temperature and the CO gas utilization rate in the furnace central region were compared with Conventional Examples 1 and 2 in which coke was not mixed into the ore due to uneven distribution of coke in the furnace central region. A decrease was observed (not shown). However, fluctuations in the Si concentration in the hot metal and the hot metal temperature, which are thought to be caused by the ore uneven distribution in the furnace central region, were observed, and the number of slips was only slightly reduced, and the degree of improvement in operation stabilization was insufficient. This is because the co-charged coke has a low particle size ratio to the coarse-grained ore, so the co-charged coke does not sufficiently classify and deposit the coarse-grained ore, and the ore is unevenly distributed in the furnace central region. As shown, the deposition O / C ratio in the furnace central region was not controlled to a low level.

By the way, for example, the condition of Comparative Example 1 satisfies the relationship between the coke mixing ratio and the mixed coke particle size described in the claims of JP-A-4-63212. That is, the coke mixing ratio to ore is 4.2
As shown in FIG. 5 (b), the average particle size of the 20% by weight of the coke of Comparative Example 1 mixed with the ore was 68.4 mm from the coarser one. Well above the minimum value set, ie, 20 + 4.2 = 24.2 mm. However, as described above, the degree of improvement in operation stabilization was insufficient. This is disclosed in Japanese Unexamined Patent Publication No. 4-63.
The range indicated in JP-A-212 shows that the charging conditions for maintaining stable blast furnace operation are insufficient.

[0049] By contrast, Examples 1, 2, 3, and 4 were more than 2.5 times a coarse D _O to D _C decreased slip occurrence count, the furnace condition was stable. In Examples 1, 2, 3 and 4, as shown in FIG. 7, the furnace top gas temperature in the central part of the blast furnace was increased, and the gas flow in the central part of the blast furnace was stabilized. In addition, as shown in FIG. 8, the gas utilization rate in the central part is reduced, and the deterioration of the core coke caused by the reaction of C + CO ₂ → 2CO and C + H ₂ O → CO + H ₂ is suppressed.
The decrease in the core coke particle size by the tuyere coke sample measurement shown in (1) was small. Examples 1, 2, 3 and 4
Then, as shown in FIG. 6, the O / C
Since the ratio can be controlled to a low level, pulverization of coke due to reaction deterioration is suppressed, and a furnace core coke having good air permeability and liquid permeability is formed. For this reason, a stable gas flow in the central region of the furnace is secured, and the blowing pressure is reduced, so that stable operation can be maintained. And the fluctuation of Si concentration and hot metal temperature in hot metal could be reduced.

Further, Example 1 (Y / X = 0.15) gave better conditions in the furnace than Example 2 (Y / X = 0.22). In Example 2, since the co-charging coke amount increases,
The amount of coke charged alone decreases, while the amount of coke unevenly distributed to the furnace center region increases.

Therefore, the region having a low deposited O / C ratio in the furnace central region spreads to the furnace middle region, and the deposited O / C in the region from the furnace middle to the vicinity of the furnace wall is increased (FIG. 6A). For this reason, as shown in FIG. 7 (b), the region where the gas utilization rate is low expands in the blast furnace radial direction, and as shown in FIG. 7 (a), the furnace top gas temperature is lower than in the first embodiment. It is high in the furnace center and in the vicinity of the furnace wall, and low in the middle area of the furnace, which tends to promote an unbalance in the radial gas flow distribution. From this result, not less than 2.5 times a coarse D _O to D _C, and by the Y / X 0.2 or less, it can be more accurately control the deposition O / C ratio of the furnace center region.

Further, in the fourth embodiment in which the coke priority charging is performed, the gas flow distribution in the radial direction is appropriately controlled similarly to the third embodiment in which the raw material mixing charging is performed, and the deposition O / C in the central region of the furnace is also controlled. The ratio could be lower than in Example 3.

[0053]

According to the method of the present invention, the O / C ratio at the center of the blast furnace can be controlled to a low level without newly providing a charging device. Therefore, it is possible to reduce the amount of coke reaction deterioration in the central part of the blast furnace, maintain the rising gas flow rate in the central part of the blast furnace at a higher level than before, secure the air permeability and liquid permeability of the blast furnace core, and improve the furnace condition. It can be kept stable.

[Brief description of the drawings]

1 shows a 1/7 scale blast furnace top half-cut model of an actual blast furnace used in a charging experiment, wherein (a) is a three-dimensional perspective view and (b) is a half-cut vertical cross-sectional view.

FIG. 2 is a diagram showing a relationship between a raw material uneven distribution state in a blast furnace radial direction and an ore to coke particle size ratio.

FIG. 3 is a diagram showing an influence of a charging pattern on a raw material uneven distribution state in a blast furnace radial direction.

FIG. 4 is a diagram illustrating a classifying deposition effect in a process of depositing mixed raw material particles in a furnace.

FIG. 5 is a diagram showing a particle size distribution of a charged raw material, wherein (a) is ore and (b) is coke.

6A and 6B are diagrams showing the distribution of deposited O / C in the blast furnace radial direction under various test conditions, wherein FIG. 6A shows the case where no movable armor is used, and FIG. 6B shows the case where movable armor is used.

FIG. 7 is a diagram showing a comparison between a furnace top gas temperature distribution and a CO gas utilization rate distribution in a blast furnace radial direction in an example and a conventional example when a movable armor is not used.

FIG. 8 is a diagram illustrating a comparison between a furnace top gas temperature distribution and a CO gas utilization rate distribution in a blast furnace radial direction in an example in which a movable armor is used and a conventional example.

Continued on the front page (72) Inventor Masahiro Kashiwada 1850 Minato, Wakayama-shi Sumitomo Metal Industries Co., Ltd. Inside Wakayama Steel Works (72) Inventor Chief Ueshiro 4-33 Kitahama, Chuo-ku, Osaka-shi, Osaka Sumitomo Metal Industries Co., Ltd. In-company (58) Field surveyed (Int. Cl. ⁶ , DB name) C21B 5/00 311 C21B 5/00 301

Claims (3)

(57) [Claims] When operating a blast furnace by repeating charging of coke alone and charging of ore and coke at the same time, the weight percentage weighted average particle size of coke charged simultaneously with ore is determined by the coarse ore particle size. A blast furnace operating method characterized in that the bulk volume ore occupying 10% by volume of the total ore is at least 2.5 times the weighted average particle size of the bulk ore. 2. When operating a blast furnace by repeating charging of coke alone and charging of ore and coke at the same time, the weight percentage weighted average particle size of coke charged at the same time as the ore is determined by the coarse ore particle size. The bulk volume ratio of the coarse ore occupying 10% by volume of the total ore is 2.5 times or more the weighted average particle size, and the amount of the ore charged at the same time (bulk volume%,
A method for operating a blast furnace, wherein the relationship with the amount of coke (bulk volume%, Y) is adjusted so as to satisfy the following expression as in X). Y ≦ 0.2 × X ・ ・ ・ 3. When co-charging ore and coke, coke is first deposited on the bottom of the ore reservoir between the large bell cup and the large bell, and ore is deposited on the top of the ore. The blast furnace operating method according to claim 1 or 2, wherein a charging pattern is set such that charging of coke is completed prior to charging of ore.