KR102182443B1 - How to load raw materials into the blast furnace - Google Patents

Abstract

In the blast furnace operation by forming a coke-mixed ore layer and a coke layer in the blast furnace, the amount of coke mixed in the coke-mixed ore layer is appropriately controlled according to the content of powdery coke in the coke forming the coke layer, and Ensure breathability. A method of loading raw materials into a blast furnace in which a coke mixed ore layer and a coke layer are formed in a layered form, with a particle size measurement sensor installed above a conveying facility that conveys coke forming a coke layer, with a short diameter in the coke in the range of 5 mm to 35 mm. When the ratio of coke particles having an arbitrary short diameter or less of is measured, and the condition that coke for forming a coke layer does not contain coke particles having a short diameter of 35 mm or less is defined as a reference condition, based on the measured ratio , The amount of coke mixed in the mixed raw material is set to be less than the amount of coke mixed in the reference condition, and coke in the amount of difference from the reference condition is blended as coke forming a coke layer.

Description

How to load raw materials into the blast furnace

The present invention relates to a method for charging raw materials into a blast furnace. Specifically, in a blast furnace operation in which a coke mixed ore layer and a coke layer are formed in a layered form in the blast furnace, the amount of coke mixed in the coke mixed ore layer is appropriately controlled according to the properties of the coke forming the coke layer, It relates to a method of charging raw materials to a blast furnace to ensure ventilation inside the blast furnace.

Recently, reduction of CO ₂ has been demanded from the viewpoint of preventing global warming. In the steel industry, it is about 70% by weight of CO ₂ emission is discharged from the blast furnace for producing pig iron, there is a need for the reduction of CO ₂ emission from the furnace. The reduction of CO ₂ in the blast furnace can be achieved by reducing reducing materials (coke, pulverized coal, natural gas, etc.) used in the blast furnace. In addition, in a blast furnace, iron ore as a raw material (also simply referred to as ``ore'') and coke as a reducing material are usually charged from the furnace top so that they are alternately layered to form an ore layer and a coke layer in the blast furnace.

On the other hand, when reducing the reducing material, particularly coke, since the coke that ensures air permeability in the furnace decreases, the ventilation resistance in the blast furnace furnace increases. In a general blast furnace, when the iron ore charged from the furnace top reaches a temperature at which softening starts, the ore layer is deformed while filling the voids by the self-weight of the raw material existing thereon. Therefore, in the lower part of the blast furnace, the air permeation resistance of the ore layer is very large, and a fused layer (referred to as a "fusion zone") through which gas hardly flows is formed. The air permeability of this fusion zone greatly affects the air permeability of the blast furnace as a whole, thereby controlling the productivity in the blast furnace.

As a means of improving the air permeability of the fusion zone, a raw material obtained by mixing ore and coke with a relatively small particle diameter (referred to as ``mixed raw material'') and coke with a relatively large particle diameter are alternately charged in the blast furnace, and mixed raw material It is known that it is effective to form a coke mixed ore layer composed of and a coke layer composed of coke having a relatively large particle diameter in a layered form. In short, it is known that it is effective to mix coke in an ore layer, and many techniques for forming a coke-mixed ore layer have been proposed.

For example, in Patent Document 1, in a Beles-type blast furnace, coke is charged into a hopper on the downstream side of the ore hopper, coke is deposited on the ore on a conveyor, and then loaded into a furnace bunker to rotate the ore and coke. A technique for charging into the blast furnace through a chute has been proposed.

In Patent Document 2, in a belles-type blast furnace, when coke or ore stored in a plurality of furnace top bunkers is charged from the center of the furnace toward the furnace wall in the radial direction of the furnace, the coke stored in one of the furnace top bunkers is From the point when the discharge from the road bunker reaches a predetermined amount between 5 to 50 mass% of the coke charge for one batch, the technology to start discharging the ore stored in the other route bunker, and to simultaneously charge coke and ore Is proposed. Thus, it is described that three types of batches for normal charging of coke, batches for central charging of coke, and batches for mixed charging can be carried out at the same time.

In Patent Document 3, in order to prevent the destabilization of the shape of the fusion zone in the blast furnace operation and the decrease in the gas utilization rate in the vicinity of the center, and to improve the stable operation and thermal efficiency, the blast furnace is completely mixed with all ore and all coke. A technology for charging raw materials to be charged inside has been proposed.

In addition, in Patent Document 4, as a means of enjoying the effect of improving the reactivity due to the mixed coke, a technique for improving the reactivity of the blast furnace by mixing high-reactive coke and ore with low JIS reducibility to react low-reactive ore with high efficiency. Is proposed.

On the other hand, since the loading amount of coke into the furnace (also referred to as "coke ratio") is almost constant, when coke is mixed with ore, the thickness of the coke layer is relatively reduced. It is known empirically that when the thickness of the coke layer in the blast furnace decreases, the air permeation resistance in the fusion zone in which the ore is softened and melted increases, thereby inhibiting stable operation.

In order to prevent an increase in air permeation resistance due to such a decrease in the thickness of the coke layer, several proposals have been made. For example, in Patent Document 5, in order to prevent the local coke layer thickness from decreasing, the range of coke charging at the furnace entrance is set to be 40% or more from the furnace wall side in the furnace radial direction. A technique has been proposed in which the average coke layer thickness of one layer at the inlet is 60 cm or more. In addition, Patent Document 6 proposes a technique of adjusting the loading amount of coke in the furnace top so that the thickness of the coke layer in the abdomen of the furnace is 250 mm or more on average.

Patent Literature 5 and Patent Literature 6 are operating conditions when coke is not mixed in the ore in a large amount, and when coke is mixed in a large amount in the ore, the air permeability of the coke mixed ore layer (ore layer) is improved, so the coke layer thickness It is believed that the lower limit of can be relaxed.

Japanese Laid-Open Patent Publication No. Hei 3-211210 Japanese Laid-Open Patent Publication No. 2004-107794 Japanese Laid-Open Patent Publication No. 53-152800 Japanese Laid-Open Patent Publication No. 64-36710 Japanese Laid-Open Patent Publication No. Hei 7-18310 Japanese Laid-Open Patent Publication No. Hei 11-506393

By the way, the coke forming the coke layer is used after being sieved with a classifier having a predetermined sieve size, but when all coke (hereinafter also referred to as ``powder coke'') of a size less than the size of the sieve of the classifier is sieved There is no. Therefore, in normal blast furnace operation, the properties of coke forming the coke layer are varied, and the content of powdery coke in the coke layer varies according to the properties of the coke layer.

In the coke layer, since the air permeability deteriorates when the content of powdery coke increases, in this case, it is necessary to increase the thickness of the coke layer to ensure the air permeability of the coke layer, that is, air permeability of the blast furnace. However, when the thickness of the coke layer is increased, it is necessary to reduce the amount of coke mixed with the mixed raw material. This is because, when the amount of coke mixed with the mixed raw material is not lowered, the reducing material becomes excessive, and not only the amount of CO ₂ discharged increases, but also the manufacturing cost increases.

In short, in order to perform a stable blast furnace operation, the content of the powdery coke in the coke forming the coke layer is detected in advance, the thickness of the coke layer is increased or decreased according to the detected content of the powdery coke, and mixed raw materials It is necessary to reduce or increase the amount of coke mixed for. However, the said patent documents 1-6 do not consider this point at all.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for charging a raw material into a blast furnace in which a coke mixed ore layer and a coke layer are formed in a layered form in a blast furnace, in which powder phase in coke forming a coke layer Depending on the content of coke, the thickness of the coke layer is increased or decreased, and the amount of coke mixed in the coke mixed ore layer is appropriately controlled, thereby providing a method of charging raw materials into the blast furnace, which can ensure ventilation inside the blast furnace. will be.

The gist of the present invention for solving the above problem is as follows.

[1] Mixed raw materials and coke mixed with iron ore and coke are charged alternately from the blast furnace furnace top,

A raw material charging method for a blast furnace in which a coke mixed ore layer made of the mixed raw material and a coke layer made of coke are formed in a layered shape in a furnace,

A particle size measurement sensor installed above a conveying facility that conveys the coke for forming the coke layer to the blast furnace, and the minor diameter of the particles contained in the coke conveyed by the conveying facility is less than or equal to an arbitrary short diameter in the range of 5 mm to 35 mm. Measure the proportion of coke particles,

When the condition in which the coke for forming the coke layer does not contain coke particles having a short diameter of 35 mm or less is defined as a reference condition, based on the measured ratio, the amount of coke mixed in the mixed raw material is determined under the reference condition. Set less than the amount of coke mixed in the mixed raw material,

A raw material charging method for a blast furnace, wherein coke of a difference between the amount of coke mixture in the reference condition and the amount of coke mixture set based on the ratio is allocated as coke for forming a coke layer.

[2] The raw material charging method for the blast furnace according to [1], wherein the amount of coke mixed in the mixed raw material is set to be equal to or less than the upper limit of the amount of coke that is calculated by substituting the measured ratio into the following formula (1).

MIX = [(9/10) × α-69/2] × β + 200… (One)

Here, in the formula (1), MIX is the upper limit of the amount of coke mixed in the mixed raw material (kg/metallic-ton), α is the short diameter of the coke particles, an arbitrary value in the range of 5 mm to 35 mm, and β is, It is the proportion (mass %) of coke particles having a short diameter of α mm or less.

In the present invention, in the method of loading a raw material into a blast furnace in which a coke mixed ore layer and a coke layer are formed in a layered form, a particle size distribution of coke for forming a coke layer is measured in a coke transport facility for the blast furnace. Then, based on the measurement result of this particle size distribution, the amount of coke mixed in the coke mixed ore layer was set, and the set amount of coke mixed and the standard condition, of coke particles having a short diameter of 35 mm or less, among coke for forming a coke layer. The coke amount of the difference between the coke mixing amount in the case where the ratio of is zero is assigned as coke forming the coke layer. Thereby, in the case of coke with a large coke content of fine grains, the thickness of the coke layer increases, and as a result, air permeability of the coke layer, that is, air permeability in the blast furnace furnace, is secured, and stabilization of the operation of the blast furnace is realized.

1: is a figure which defines the short diameter of coke particle.
Fig. 2 is a schematic diagram of a test apparatus used to measure the relationship between the thickness of a coke layer and the fusion zone ventilation resistance.
3 is a diagram showing a relationship between a ratio of coke particles having a short diameter of 5 mm or less and an upper limit value of the amount of coke mixed in the mixed raw material.
4 is a diagram showing a relationship between a ratio of coke particles having a short diameter of 35 mm or less and an upper limit value of the amount of coke mixed in a mixed raw material.
5: is a figure which shows the relationship between the ratio β when the upper limit value MIX becomes 50 kg/molten iron-ton, and the short diameter α of coke particles.

Hereinafter, the present invention will be described in detail.

In a blast furnace operation in which a coke-mixed ore layer composed of a mixed raw material of iron ore and coke is formed and a coke layer is formed in layers in the blast furnace, powdery coke in the coke forming the coke layer (less than the size of the classifier When the content of coke) of the size of is increased, the air permeability of the coke layer, that is, the air permeability inside the blast furnace deteriorates. Therefore, in this case, it is necessary to reduce the amount of coke mixed in the coke mixed ore layer, and charge the amount corresponding to the reduced amount as the coke layer to increase the thickness of the coke layer, thereby securing air permeability inside the blast furnace. .

The present inventors use a test apparatus capable of simulating the air permeability resistance of the fusion zone inside the blast furnace for the purpose of stably securing the air permeability inside the blast furnace even when the content of the powdered coke of the coke forming the coke layer changes. Tested.

Usually, the coke forming the coke layer is sieved by a classifier having a sieve size of 35 mm, and then conveyed to the blast furnace and charged into the blast furnace. It is well known to those skilled in the art that if it is coke of a size that does not pass through a classifier having a sieve size of 35 mm, the air permeability of the fusion zone inside the blast furnace can be ensured. However, coke particles of the size to be sieved by a classifier having a sieve size of 35 mm are also mixed in the coke after being sieved with a classifier having a sieve size of 35 mm. In addition, coke is powdered even by a drop impact during conveyance to the blast furnace.

In this specification, coke of a size to be sieved by a classifier having a sieve size of 35 mm, contained in the coke forming the coke layer, is referred to as "coke having a short diameter of 35 mm or less". Similarly, coke of a size to be sieved by a classifier having a sieve size of α mm is referred to as "coke having a short diameter of α mm or less". Here, "short diameter of coke particles" is an intersection point when the distance between the intersection of the intersection of the circumference of the projection surface and the straight line passing through the center of gravity of the coke particles in the projection plane of the coke particles becomes the shortest, as shown in FIG. It is defined as the inter-distance.

In the test, paying attention to the content of coke particles having a short diameter of 35 mm or less in the coke forming the coke layer, as a condition for ensuring the air permeability of the fusion zone inside the blast furnace, any short diameter having a short diameter in the range of 5 mm to 35 mm The relationship between the content ratio of the following coke particles and the amount of coke mixed in the coke mixed ore layer was investigated.

Fig. 2 shows a schematic diagram of a test apparatus used to measure the relationship between the thickness of the coke layer and the fusion zone ventilation resistance. In the drawing, reference numeral 1 denotes a sample heating furnace, and the sample heating furnace 1 includes a sample filling container 2 and a heating device 3 therein. In addition, the sample filling layer 6 in which the coke layer 4 and the coke mixed ore layer 5 are layered is formed inside the sample filling container 2. And the temperature of the sample-filled layer 6 is controlled by the heating device 3. Reference numeral 7 denotes a gas heating furnace, and this gas heating furnace 7 also has a heating device 8 therein. In addition, numeral 9 is a gas mixer, 10 is a gas flow pipe, 11 is a pressure gauge, 12 is a thermocouple, 13 is a pressure plate, 14 is a pedestal, 15 is a connecting rod, and the connecting rod 15 is made of graphite or metal. desirable. In addition, reference numeral 16 denotes a load means, and in the example of this test apparatus, a weight 16 is used as the load means. Then, the load simulating the inside of the blast furnace is applied to the sample packed layer 6 by this weight 16.

As shown, this test apparatus has the greatest feature in that the sample heating furnace 1 and the gas heating furnace 7 are arranged in series, and in this way, in the gas heating furnace 7 The heated gas enters the sample heating furnace 1 in the transverse direction.

In this test apparatus, coke obtained by adjusting the proportion of particles having a minor diameter of 5 mm or less in a range of 0 to 5.0 mass%, and coke having a proportion of particles having a minor diameter of 35 mm or less in a range of 0 to 50% by mass are used. The layer 4 was formed, and the amount of coke mixed in the coke-mixed ore layer 5 was variously changed to investigate the air permeability. In this specification, the condition in which coke for forming a coke layer does not contain coke particles having a short diameter of 35 mm or less was defined as a reference condition.

Specifically, when the ratio of coke particles having a short diameter of 35 mm or less in the coke for forming the coke layer is zero, that is, the amount of coke mixed in the coke mixed ore layer 5 in the reference condition is 200 kg/charter- Tones. And since the air permeability deteriorates with an increase in the content of powdery coke in the coke for forming the coke layer 4, in order to secure it, the coke mixed in the coke mixed ore layer 5 was mixed with the coke layer ( 4) was assigned under various conditions, and ventilation was investigated. And the coke mixing ratio in the coke mixed ore layer 5 in the test in which the pressure loss in the test and the pressure loss in the reference condition (a condition that does not contain coke particles having a short diameter of 35 mm or less) are equal (kg/ Molten iron-tone) was determined according to the proportion of particles having a short diameter of 5 mm or less and a proportion of particles having a short diameter of 35 mm or less.

The results obtained in the test are shown in FIGS. 3 and 4. Fig. 3 is a diagram showing the relationship between the ratio of coke particles having a short diameter of 5 mm or less and the upper limit of the amount of coke mixed in a mixed raw material in a test using coke in which the proportion of particles having a short diameter of 5 mm or less is changed. Fig. 4 is a diagram showing the relationship between the ratio of coke particles having a short diameter of 35 mm or less and the upper limit of the amount of coke mixed in a mixed raw material in a test using coke in which the proportion of particles having a short diameter of 35 mm or less is changed. In Figs. 3 and 4, the coke mixing ratio (kg/melt iron-ton) that becomes the pressure loss equivalent to the pressure loss in the reference condition is indicated as an upper limit value.

As shown in FIGS. 3 and 4, the ratio of the particles having a short diameter of 5 mm or less or 35 mm or less, indicated by the horizontal axis, and the upper limit value of the amount of coke mixed in the mixed raw material indicated by the vertical axis, were in a linear relationship. From this relationship, it is understood that the upper limit value of the amount of coke mixed in the mixed raw material and the ratio of coke particles having a short diameter of 5 mm or less or 35 mm or less are represented by a linear equation. Moreover, when the short diameter is 5 mm or less and the short diameter is 35 mm or less, the influence of the proportion of coke particles on the upper limit of the amount of coke mixed is different.

From this, the upper limit of the amount of coke mixed in the mixed raw material is MIX (kg/molten iron-ton), the short diameter of the coke particles is α (mm), and the ratio of the coke particles having a short diameter of 5 mm or less or 35 mm or less is determined. When it is set to β (mass%), these factors are represented by the following (2) formula. In addition, 200 in the formula (2) is the amount of coke mixed (kg/molten iron-ton) under the reference conditions, and A and B are coefficients.

MIX = (A × α + B) × β + 200… (2)

When the ratio β of coke particles having a short diameter of 5 mm or less in FIG. 3 is 5% by mass, the condition that MIX is 50 kg/metallic-tone, and the ratio β of coke particles having a short diameter of 35 mm or less in FIG. 4 is 50% by mass. When the condition under which MIX is 50 kg/charter-ton is substituted into Equation (2) and the coefficient A and the coefficient B are obtained, A = 9/10 and B = -69/2 are obtained. In short, the formula (2) is represented by the following formula (1).

MIX = [(9/10) × α-69/2] × β + 200… (One)

Here, in the formula (1), MIX is the upper limit of the amount of coke mixed in the mixed raw material (kg/metallic-ton), α is the short diameter of the coke particles, an arbitrary value in the range of 5 mm to 35 mm, and β is the short diameter α It is the ratio (mass %) of the coke particle which is mm or less.

(1) In order to confirm the validity of the formula, the ratio of coke particles having a short diameter of 20 mm or less is changed, and the ratio of coke particles having a short diameter of 20 mm or less when the upper limit MIX of the amount of coke mixture is 50 kg/charter-ton. β was calculated. As a result, it was found that when the ratio β of coke particles having a short diameter of 20 mm or less was 28% by mass, the upper limit value MIX of the amount of coke mixed was 50 kg/melt-ton.

Thus, in each of the tests in which α = 5 mm, α = 20 mm, and α = 35 mm, comparison was made for each ratio β when the upper limit MIX was 50 kg/charter-tone. 5 shows the relationship between the ratio β and the short diameter α, with the horizontal axis as the short diameter α (mm) of the coke particles, and the vertical axis as the ratio β (mass%) when the upper limit MIX is 50 kg/metallic-tone It is a drawing. As shown in FIG. 5, it was found that the ratio β (mass %) when the upper limit MIX is 50 kg/metallic-tone and the short diameter α (mm) of the coke particles are represented by the relationship of a linear equation. In short, it was confirmed that the formula (1) is valid as long as α is in the range of 5 to 35 mm.

In addition, the formula (1) is that the amount of coke mixed in the coke mixed ore layer in the case where the ratio of coke particles having a short diameter of 35 mm or less in the coke for forming the coke layer is zero (reference conditions) is 200 kg/charter-ton. Although it is a case, in carrying out the present invention, it is not necessary to limit the amount of coke mixture in the reference condition to 200 kg/charter-ton.

In the blast furnace operation, the coke ratio (kg/charter-ton) required for the reduction reaction of iron ore and the increase in temperature of the generated molten iron is generally about 300 kg/charter-ton, but changes according to the operating conditions of each blast furnace. In addition, the coke ratio is the total amount of coke charged (kg/charter-ton) to be blended in both the coke mixed ore layer and the coke layer. In short, if the coke ratio is CR (kg/charter-ton), the amount of coke mixed in the coke-mixed ore layer under the reference condition is the amount obtained by multiplying the coke ratio CR by a certain mixing ratio γ (-) (CR × It can be expressed as γ).

The present invention was made on the basis of the above test results, and the method of charging a raw material to a blast furnace according to the present invention comprises: a mixed raw material in which iron ore and coke are mixed and coke are alternately charged from a blast furnace furnace top, and coke made of the mixed raw material. A method for charging raw materials into a blast furnace in which a mixed ore layer and a coke layer composed of the coke are formed in a layered shape in a furnace, and is installed above a conveying facility (belt conveyor, etc.) that transports coke for forming the coke layer to the blast furnace. With a particle size measurement sensor, a ratio of coke having a minor diameter of particles contained in the coke conveyed by the conveying facility is less than or equal to an arbitrary minor diameter in the range of 5 mm to 35 mm, and based on the measured proportion, in the mixed raw material The amount of coke mixed is reduced from the amount of coke mixed in the case where the ratio of coke particles having a short diameter of 35 mm or less, which is a reference condition, in the coke for forming the coke layer is zero, based on the amount of coke mixed in the reference condition and the ratio. The amount of coke in the difference between the amount of coke mixture set in this manner is allocated as coke for forming a coke layer. In short, in the blast furnace operation in which the coke ratio (kg/charter-ton) is constant, the amount of coke mixture set based on the amount of coke mixed under the reference conditions and the content of powdery coke in the coke for forming the coke layer 4 The amount of coke in the difference of is blended as coke forming a coke layer.

In addition, it is preferable to replace the difference of the amount of coke from the coke mixture layer to the coke layer because there is no increase or decrease in the reducing material ratio and air permeability can be secured, but it is possible to make the replacement amount ±5 kg/charter-ton.

In the case of replacing the coke blended in the coke mixture layer with the coke layer, it is preferable to set the amount of coke mixture in the mixed raw material to be less than the upper limit of the amount of coke mixture calculated by substituting the measured ratio into the equation (1) above. .

That is, in the present invention, if the fine grains (shorter diameter 35 mm or less) contained in the coke forming the coke layer increase, the air permeability of the coke layer deteriorates. Therefore, the coke blended in the coke mixed ore layer is coke By allocating to the floor, ventilation inside the blast furnace is ensured. By adjusting the amount of coke in this way, the coke ratio (kg/charter-ton) is maintained at a certain predetermined value.

As a particle size measurement sensor that measures the particle size distribution of coke, for example, "The object to be measured is imaged by an image pickup device, and the imaged circle is disclosed in Publication 1 (Publication 1; Japanese Patent Laid-Open No. 2003-83868). From an image, a blurring image obtained by subjecting the original image to a blurring treatment is obtained, and the blurring image is subjected to a binarization process to measure the distribution of the particle diameter of a measurement object having a predetermined particle diameter or more, and the captured original image and blur. By binarizing the difference image formed by the difference in the ring image, the distribution of the particle diameter of the measurement object less than the predetermined particle diameter is measured, and the overall particle diameter distribution is measured based on the measurement results of these two types of particle diameter measurement distribution. A measuring device or the like using the particle size distribution measuring method" may be used. Specifically, a particle size measurement sensor capable of detecting the distance between intersections shown in Fig. 1 by image processing is used.

As described above, according to the present invention, in the coke transport facility for the blast furnace, the particle size distribution of coke forming the coke layer is measured, and based on the measurement result of the particle size distribution, the amount of coke mixed in the coke mixed ore layer and Since the amount of coke blended to the coke layer is controlled, air permeability in the blast furnace furnace is ensured, and stabilization of the operation of the blast furnace is realized.

Example

In a practical blast furnace, when the raw material is charged by applying the present invention under the conditions of the same coke ratio and the same starting line ratio, and when the raw material is charged outside the scope of the present invention, gas utilization rate and pressure loss in the packed bed The results of the investigation are compared and shown. As a particle size measurement sensor for measuring the particle size distribution of coke, a measurement device using the particle size distribution measurement method disclosed in Publication 1 is used, and this measurement device is a belt conveyor that conveys coke for forming a coke layer to a blast furnace. It was installed on the upper side.

In coke for forming a coke layer, the proportion of coke particles having a short diameter of 5 mm or less was measured by a particle size measurement sensor. The amount of coke mixed in the mixed raw material (kg / molten iron-ton) is equal to or less than the upper limit of the amount of coke mixed (kg / molten iron-ton) calculated by substituting the measured value of the ratio of coke particles having a short diameter of 5 mm or less into the formula (1). The case of adjusting (Invention Examples 1 and 2) and the case of setting the amount of coke mixed in the mixed raw material (kg/charter-ton) exceeding the upper limit value according to the formula (1) (Comparative Examples 1 and 2) were compared. It is shown in Table 1.

Moreover, in coke for forming a coke layer, the ratio of coke particles having a short diameter of 35 mm or less was measured by a particle size measuring sensor. The amount of coke mixed in the mixed raw material (kg / molten iron-ton) is equal to or less than the upper limit of the amount of coke mixed (kg / molten iron-ton) calculated by substituting the measured value of the ratio of coke particles having a short diameter of 35 mm or less into the formula (1). In the case of adjustment (Invention Examples 3 and 4) and the case where the amount of coke mixed in the mixed raw material (kg/charter-ton) exceeded the upper limit value according to the formula (1) (Comparative Examples 3 and 4) It is shown in Table 2.

As shown in Tables 1 and 2, when the present invention was applied, it was confirmed that the gas utilization rate was improved and the pressure loss in the packed bed was reduced. In short, it was confirmed that stable blast furnace operation became possible by applying the present invention.

1: sample heating furnace
2: sample filling container
3: heating device
4: coke layer
5: coke mixed ore layer
6: sample filled layer
7: gas heating furnace
8: heating device
9: gas mixer
10: gas distribution piping
11: pressure gauge
12: thermocouple
13: pressing plate
14: pedestal
15: connection rod
16: weight

Claims (2)

The mixed raw material of iron ore and coke and coke are charged alternately from the blast furnace top,
A raw material charging method for a blast furnace in which a coke mixed ore layer made of the mixed raw material and a coke layer made of coke are formed in a layered shape in a furnace,
A particle size measurement sensor installed above a conveying facility that conveys the coke for forming the coke layer to the blast furnace, and the proportion of coke particles having a short diameter of 5 mm or less or 35 mm or less of the particles contained in the coke conveyed by the conveying facility And measure
When the condition that the coke for forming the coke layer does not contain coke particles having a short diameter of 35 mm or less is defined as a reference condition, based on the measured ratio with the short diameter of the coke particles, it is equivalent to the pressure loss in the reference condition. Calculate the amount of coke mixture to be compressed, and set the amount of coke mixture in the mixed raw material to be equal to or less than the calculated amount of coke mixture,
A raw material charging method for a blast furnace, wherein coke of an amount of the difference between the coke mixing amount and the set coke mixing amount under reference conditions is allocated as coke for forming a coke layer. The method of claim 1,
A raw material charging method for a blast furnace, wherein the amount of coke mixed in the mixed raw material is set to be equal to or less than the upper limit of the amount of coke calculated by substituting the measured ratio into the following equation (1).
MIX = [(9/10) × α-69/2] × β + 200… (One)
Here, in equation (1),
MIX is the upper limit of the amount of coke mixed in the mixed raw material (kg/metallic-ton)
α is the short diameter of the coke particle, 5 mm or 35 mm,
β is the proportion (mass%) of coke particles having a short diameter of α mm or less,
When α is 5 mm, it is in the range of 0 to 5 mass%,
When α is 35 mm, it is in the range of 0 to 50 mass%.

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