JP6954255B2 - Calculation method of mixing ratio of ferro-coke and blast furnace operation method - Google Patents

Description

The present invention adjusts the calculation method for calculating the mixing ratio of ferrocoke in the ore layer deposited in the blast furnace and the charging method for ore and ferrocoke so that the mixing ratio of ferrocoke in the ore layer becomes a target value. Regarding the operation method of the blast furnace.

In order to reduce the reducing agent ratio of the blast furnace, it is effective to use ferro-coke as a raw material for the blast furnace and to utilize the effect of lowering the temperature of the heat storage zone of the blast furnace by using the ferro-coke. Ferrocoke, which is produced by carbonizing a molded product obtained by mixing coal and iron ore, has high reactivity, which promotes the reduction of sintered ore and contains partially reduced iron ore. Therefore, the temperature of the heat storage zone of the blast furnace can be lowered, and the ratio of reducing agents can be reduced.

Examples of the blast furnace operation method using ferro-coke include a method in which ore and ferro-coke are mixed and charged into the furnace of the blast furnace. _{Ferrocoke has higher reactivity with CO 2} gas represented by the following formula (1) than coke for metallurgy produced by carbonizing coal. The reaction of the following formula (1) can be said to be a reaction of regenerating _{CO 2} produced by the reduction of the ore represented by the following formula (2) into a CO gas having a reducing power.

CO ₂ + C → 2CO ・ ・ ・ (1)

FeO + CO → Fe + CO ₂ ... (2)

Therefore, if the reaction of the above formula (1) occurs promptly in the region where the _{CO 2} gas concentration is increased by the reaction of the above formula (2) _{, the CO 2} gas is rapidly regenerated into a CO gas having a reducing power. Therefore, the reduction of ore is promoted.

In order to fully exhibit the effect of promoting the reduction of ore by ferro-coke, the mixed state of ore and ferro-coke in the radial direction of the blast furnace is important. Generally, in a blast furnace, in order to ensure air permeability, a large amount of coke is placed on the center side of the furnace to secure a gas escape route to stabilize the operation. Since there is little ore in the place where a lot of coke is placed, even if ferro-coke is placed, the CO gas regenerated by the reaction of the above formula (1) reaches the furnace top as it is without being used for the reduction of the ore. , It will be discharged to the outside of the furnace. Since the reaction of the above formula (1) is an endothermic reaction, if the regenerated CO gas is not used for the reduction of the ore, the temperature in the furnace will decrease and the amount of heat will be compensated for, so that the ratio of the reducing agent can be increased. You will need it. Therefore, in order to fully exhibit the effect of ferro-coke, it is important to charge the ferro-coke so that the mixing ratio of the ferro-coke with respect to the ore is as uniform as possible.

Patent Document 1 discloses that it is preferable to uniformly mix ferro-coke in the ore. According to Patent Document 1, it is disclosed that by uniformly mixing and charging the ore and the ferro-coke, the ratio of the reducing agent can be reduced as compared with the case where the ore and the ferro-coke are charged separately.

Patent Document 2 discloses that by mixing a predetermined amount of ferrocoke at a predetermined layer height direction and radial position, the reducing agent ratio can be reduced as compared with the case where the ferrocoke is uniformly mixed in the ore. Has been done.

In Patent Document 3, the mixing degree of the ferro-coke of the mixed raw material discharged from the furnace top bunker is used by using the mass change rate and the volume change rate of the mixed raw material composed of the ferro-coke and the ore discharged from the furnace top bunker. It is disclosed that can be calculated.

Japanese Unexamined Patent Publication No. 2006-28594 Japanese Unexamined Patent Publication No. 2011-162845 JP-A-2018-70898

According to Patent Document 1, it is preferable to uniformly mix ferro-coke in the ore, but a method of uniformly mixing the ferro-coke in the ore and whether the ferro-coke could be uniformly mixed in the ore? The method of confirming whether or not it is not disclosed.

According to Patent Document 2, the reducing agent ratio can be reduced by mixing a predetermined amount of ferro-coke at a predetermined layer height direction and radial position. However, since ferrocoke usually has a larger particle size than ore, there is a possibility that particle size segregation occurs during in-core deposition and a predetermined amount of ferrocoke is not mixed at the target position. In addition, since the particle size of the ore changes sequentially during operation, the degree of particle size segregation also changes accordingly, and the mixing ratio distribution of ferro-coke also changes. In this way, the mixing ratio distribution of ferro-cokes can change during operation, so if the mixing ratio of ferro-cokes in the ore layer deposited in the furnace of the blast furnace cannot be confirmed, the effect of continuously reducing the reducing material ratio can be obtained. I can't get it.

According to Patent Document 3, it is said that the mixing degree of the mixed raw material composed of ferro-coke and ore discharged from the furnace top bunker can be estimated. However, as described above, since particle size segregation occurs during the deposition in the furnace of the blast furnace, the mixing ratio of the ore layer deposited in the furnace cannot be calculated by this method. The present invention has been made in view of the above problems, and an object of the present invention is to provide a calculation method capable of calculating the mixing ratio of ferrocokes in an ore layer deposited in a furnace, and to determine the mixing ratio in advance. The purpose of the present invention is to provide a blast furnace operation method for adjusting the method of charging ferro-coke into the ore so as to obtain the desired mixing ratio.

The features of the present invention for solving such a problem are as follows.
[1] The blast furnace is alternately charged with ore in which coke and ferro-coke are mixed, and among the coke layers and ore layers alternately formed in the blast furnace, the mixing ratio of ferro-coke in the ore layer _{In the calculation method, the CO gas utilization rate and the H 2} gas utilization rate of at least one of the in-furnace gas and the furnace top gas of the blast furnace are measured, and the CO gas utilization rate and the H ₂ gas utilization rate are used. A method for calculating the mixing ratio of ferro-coke, which calculates the mixing ratio of ferro-coke in the ore layer.
[2] using at least one of CO gas utilization rate and H ₂ gas utilization rate of the furnace gas and the top gas at a plurality of positions in the radial direction of the blast furnace, the mixing ratio of the ferro coke ore layer in said plurality of positions The method for calculating the mixing ratio of ferro-coke according to [1].
[3] A blast furnace operating method in which ore in which coke and ferro-coke are mixed is alternately charged, and at the plurality of positions calculated by the method for calculating the mixing ratio of ferro-coke according to [2]. A blast furnace operating method for adjusting the charging method of the ore and the ferrocoke so that the mixing ratio of the ferrocoke in the ore layer becomes a predetermined mixing ratio.

According to the present invention, the mixing ratio of ferro-coke in the ore layer deposited in the furnace of the blast furnace can be calculated. In addition, by calculating the mixing ratio of ferro-coke at multiple positions in the radial direction, it is possible to understand how to adjust the charging method of ferro-coke for ore to obtain a predetermined mixing ratio of ferro-coke. By adjusting to the charging method, the mixing ratio of ferro-coke at a plurality of positions in the radial direction can be set to a predetermined target mixing ratio.

It is a schematic diagram which shows the concept of this invention. It is a graph which shows the relationship between the isotherms in each gas composition of shift equilibrium temperature of 700 degreeC and 750 degreeC, and η _CO , η _{H2 of the furnace top gas in actual operation.} It is a graph which shows the relationship between the mixing ratio of ferrocoke and the shift equilibrium temperature. It is sectional drawing which shows the structure around the furnace top bunker 24 of the blast furnace 10. It is a graph which shows the transition of the ferro-coke mixing ratio in each period in an Example. It is a graph which shows the transition of the reducing agent ratio in each period in an Example. It is a graph which shows _{the average η CO} of each period in an Example. It is a graph which shows _{the average η H2} of each period in an Example. It is a graph which shows the shift equilibrium temperature of each period in an Example. It is a graph which shows the mixing ratio of ferrocoke at a plurality of positions in a radial direction in the comparative example 2. It is a graph which shows the mixing ratio of ferrocoke at a plurality of positions in a radial direction in an example of an invention.

First, the background to the present invention will be described. FIG. 1 is a schematic diagram showing the concept of the present invention. In the furnace of the blast furnace 10, the water-gas shift reaction represented by the following formula (3) occurs, and the equilibrium state of this reaction moves to the reactant side as the temperature rises and moves to the product side as the temperature rises.

The reaction of formula (3) is considered to have almost reached equilibrium in the furnace of the blast furnace, but the composition of the top gas changes depending on the temperature at which the reaction of formula (3) reaches equilibrium. It is known that the equilibrium constant K (-) of the reaction of the formula (3) is given by the formula (4). Here, when the equation (4) is converted, the equilibrium temperature _TE (° C.) is obtained by the equation (5). Moreover, the equilibrium constant K, the use of CO gas utilization rate _{η CO (= P CO2 / (} P CO + P CO2)) and _{H 2} gas utilization rate _{η H2 (= P H2O / (} P H2 + P H2O)), wherein It is represented by (6).

η _CO and η _H2 can be measured by collecting the top gas and analyzing the composition. Measured eta _CO, and eta _H2, equation (5) can be calculated shift equilibrium temperature _{T E} with (6). As described later, since the mixing ratio of the shift equilibrium temperature T _E and ferro coke are correlated, the mixing ratio of the ferro coke can be calculated using a shift equilibrium temperature T _E. By calculating the mixing ratio of ferrocoke in this way, it is possible to determine whether or not the mixing ratio of ferrocoke in the ore layer deposited in the furnace of the blast furnace is the predetermined target ferrocoke mixing ratio. You can check. Then, if the mixing ratio of the target ferrocokes is not reached, the charging method of the ore and the ferrocokes is adjusted so as to have the target mixing ratio of the ferrocokes.

FIG. 2 is a graph showing the relationship between the isotherms in each gas composition having shift equilibrium temperatures of 700 ° C. and 750 ° C. and η _CO and η _{H2 of the furnace top gas in actual operation.} In FIG. 2, the horizontal axis is η _CO (%) and the vertical axis is η _H2 (%). The round plot shown in FIG. 2 is a plot _{showing the relationship between η CO} and η _{H2 in the operation performed without using ferrocokes, and the triangular plot is the η CO} in the operation using 50 kg / t of ferrocokes. It is a plot which shows the relationship between η _{H2 and η H2.}

In the operation performed without using ferro-coke, the reduction efficiency in the furnace changed due to the fluctuation of the raw material properties. As a result, η _CO and η _H2 changed, but the shift equilibrium temperature changed along the isotherm of 750 ° C. In the operation performed using ferro-coke, η _CO and η _H2 changed along the isotherms of the shift equilibrium temperature, but the shift equilibrium temperature decreased to 700 ° C. It is presumed that this decrease in the shift equilibrium temperature is due to the decrease in the heat storage zone temperature due to the use of ferro-coke.

In this way, since the shift equilibrium temperature was lowered by using ferrocokes, in order to confirm the relationship between the ferrocokes mixing ratio and the shift equilibrium temperature, an ore with a different ferrocokes mixing ratio was installed in the actual blast furnace. It was charged and the shift equilibrium temperature obtained from _{η CO} and η _H2 of the furnace top gas generated in the operation was confirmed.

FIG. 3 is a graph showing the relationship between the mixing ratio of ferro-coke and the shift equilibrium temperature. In FIG. 3, the horizontal axis is the mixing ratio of ferro-coke (kg / t), and the vertical axis is the shift equilibrium temperature (° C.). The unit kg / t of the mixing ratio of ferro-coke is the mass (kg) of ferro-coke used to produce 1 ton of hot metal.

As shown in FIG. 3, there is a correlation between the ferro-coke mixing ratio and the shift equilibrium temperature, and when the ferro-coke mixing ratio increased by 1 kg / t, the shift equilibrium temperature decreased by 1 ° C. From this result, the relationship between the ferro-coke mixing ratio and the shift equilibrium temperature _TE (° C.) can be expressed by the following equation (7).

_{T E = T 0 -a × FCR} ··· (7)
However, in the formula (7), T ₀ = 750 ° C., a = 1.0 ° C./(kg / t), and FCR is the ferro-coke mixing ratio (kg / t). Further, the gas to be collected is not limited to the furnace top gas, but may be a furnace gas. However, the _{values of T 0} (° C.) and inclination a (° C./(kg/t)) may differ depending on the blast furnace and whether the gas to be sampled is the in-core gas or the top gas. Therefore, it is preferable to perform the above-mentioned examination in advance for each blast furnace and each condition for collecting gas, and draw a calibration line _{to calculate T 0} and the inclination a.

Using the relationship shown in the formula (7), the inventors of the present invention collected the gas in the blast furnace 10 _{to measure η CO} and η _H2, and measured the η _CO , η _H2 and the above formula (5). )-(7) have been used to complete the present invention by finding that the mixing ratio of ferrocokes in the ore layer deposited in the blast furnace 10 can be calculated. Hereinafter, the present invention will be described through embodiments of the present invention.

In the method for calculating the mixing ratio of ferro-cokes according to the present embodiment, the blast furnace is charged with coke and ore mixed with ferro-cokes alternately, and among the coke layers and the ore layers alternately formed in the blast furnace. , Calculate the mixing ratio of ferrocokes in the ore layer. Specifically, as shown in FIG. 1, a gas sampler 12 is installed at a predetermined height in the furnace of the blast furnace 10 or at the furnace mouth portion, and the gas sampler 12 is used to and the gas in the furnace. At least one of the top gases, η _CO and η _H2, is measured, and the mixing ratio of ferro-coke is calculated using the _{η CO} , η _{H2 and the above formulas (5) to (7).} Thereby, the mixing ratio of ferro-coke in the ore layer deposited in the blast furnace 10 can be calculated.

Further, gas samplers 12 may be installed at a plurality of positions in the blast furnace in the radial direction, and at least one of the in-core gas and the top gas at the plurality of positions may be measured for _{η CO} and η _H2. Thereby, the mixing ratio of ferrocokes in the ore layer at a plurality of positions in the radial direction can be calculated using the _{η CO} , η _{H2 and the above equations (5) to (7).} That is, the gas sampled at a certain position in the radial direction is a gas that rises in the flow path corresponding to the position in the radial direction in the furnace, and corresponds to the mixing ratio of the ore and the ferro-coke at the radial position. Since the gas composition is the same, the mixing ratio of ferrocoke in the ore layer calculated at the plurality of positions is the mixing ratio distribution of ferrocoke in the radial direction.

In addition, the mixing ratio distribution of ferro-coke that can reduce the reducing agent ratio in blast furnace operation is predetermined, and the mixing ratio of ferro-coke at a plurality of positions in the radial direction has a predetermined mixing ratio distribution. It is preferable to adjust the method of charging coke. As a result, even if the particle size of the ore and the degree of particle size segregation change sequentially during the operation and the mixing ratio of the ferro-coke changes during the operation, the ferro-coke mixing ratio according to the present embodiment is used for calculating the ferro-coke. By calculating the mixing ratio of coke, the change in the mixing ratio can be grasped, and the charging method of ore and ferro-coke can be adjusted so as to obtain the target predetermined mixing ratio distribution. As a result, the mixing ratio distribution of ferrocokes in the ore layer can be brought close to the target mixing ratio distribution, and the effect of reducing the reducing material ratio can be continuously obtained.

The gas sampler 12 is installed on the shaft portion or the furnace mouth portion of the blast furnace 10, and the gas in the blast furnace 10 is collected at a specific position or a plurality of positions from the furnace wall portion to the furnace center portion, and the gas is collected. The partial pressures of H ₂ O, H ₂ , CO, and CO _{2 in} the above are measured to calculate _{η CO} and η _{H 2.} The gas sampler 12 in the present embodiment may be a fixed type capable of constantly collecting gas in the furnace, or may be a movable type that is periodically inserted into the blast furnace 10 to collect gas in the furnace. .. However, when it is movable, it is preferable to insert it into the blast furnace 10 at least once a day and collect the gas in the blast furnace 10 to calculate the mixing ratio of ferro-coke. Further, in the case of an apparatus capable of collecting gas at a plurality of positions, it is preferable to collect the gas in the furnace at five or more points between the furnace wall and the center of the furnace. Further, since the shift equilibrium temperature in the blast furnace 10 is basically 600 ° C. or higher, the shift reaction does not reach equilibrium at the position where the in-furnace temperature of the blast furnace 10 is higher than 600 ° C., and the above equation (4) does not hold. there is a possibility. Therefore, the gas sampler 12 is preferably installed at a position where the temperature inside the blast furnace 10 is 600 ° C. or lower.

FIG. 4 is a schematic cross-sectional view showing the configuration around the top bunker 24 of the blast furnace 10. A method of adjusting the mixing ratio of ferrocoke in the ore layer at a plurality of positions in the radial direction will be described with reference to FIG. In the present embodiment, a predetermined amount of ore 20 is discharged from the ore hopper 14 onto the belt conveyor 18, and a predetermined amount of ferro-coke 22 is discharged from the ferro-coke hopper 16 onto the ore 20 conveyed on the belt conveyor 18. These are charged into the furnace top bunker 24. In this case, the adjustment of the charging method of the ore 20 and the ferro-coke 22 is carried out by changing the range in which the ferro-coke 22 is superposed on the ore 20. By changing the range in which the ferro-coke 22 is superposed on the ore 20, the mixed state of the ore 20 and the ferro-coke 22 when filled in the furnace top bunker 24 is changed. As a result, the mixing ratio distribution of the ferro-coke 22 in the ore layer charged into the blast furnace 10 from the furnace top bunker 24 and deposited in the blast furnace 10 can be adjusted.

For example, when the ferro-coke 22 is superposed on the belt conveyor 18 in front of the ore 20 and discharged, a large amount of the ferro-coke 22 is discharged at the initial stage of discharge from the furnace top bunker 24. On the other hand, when the ferro-coke 22 is superposed on the belt conveyor 18 behind the ore 20 and discharged, a large amount of the ferro-coke 22 is discharged in the latter stage of the discharge from the furnace top bunker 24. By combining such a discharge tendency with the turning pattern of the bellless chute 26, the mixed state of the ferro-coke 22 at the time of deposition in the blast furnace 10 can be adjusted.

Next, a calculation method, and blast furnace method mixing ratio according to the present embodiment will embodiment was applied to the operation of 5000 m ³ grade blast furnace. When ferro-coke is used in this embodiment, as shown in FIG. 4, the ferro-coke is superposed on the ore transported on the belt conveyor 18 and discharged, and the ferro-coke is discharged from the furnace top bunker 24 and the bellless chute. 26 was charged into the blast furnace. The gas sampler is a movable gas sampler installed on the shaft of the blast furnace. It is inserted from the furnace wall toward the center of the furnace three times a day, and the gas inside the furnace is collected at seven positions in the radial direction. The shift equilibrium temperature was calculated from the gas composition at the position, and the mixing ratio of the ferrocourse at the position was calculated.

FIG. 5 is a graph showing the transition of the ferro-coke mixing ratio in each period in the examples. In FIG. 5, the horizontal axis is the period and the vertical axis is the ferro-coke mixing ratio (kg / t). The plots shown in FIG. 5 are all weekly average values.

As shown in FIG. 5, the blast furnace operation was carried out without using ferro-coke during the period of Comparative Example 1. In Comparative Example 2 and Invention Example, the blast furnace operation was carried out using 50 kg / t of ferro-coke. In the period of Comparative Example 2, 50 kg / t of ferro-coke was used, and the ferro-coke was charged on the belt conveyor 18 in a range of the rear half of the ore throughout the period.

In this embodiment, to measure the CO gas utilization and H ₂ gas utilization rate was collected furnace gas at each position in the radial direction 7 points, utilization and the formulas of these gases (5), (6) The shift equilibrium temperature was calculated using. In Comparative Example 2 and the invention, the ferro-coke mixing ratio was calculated using the equation (7). In the example of the invention, the charging method of ore and ferro-coke was adjusted so that the mixing ratio distribution of the initially adjusted ferro-coke did not change. The adjustment of the charging method is such that when the average daily mixing ratio at each position deviates from a predetermined target ferro-coke mixing ratio by a certain value or more, the ferro-coke is placed on the ore on the charging belt conveyor. The radial ferro-coke mixing ratio distribution was adjusted by changing the overlapping range. In this example, the production amount was kept constant throughout the entire period, and the reducing agent ratio was adjusted so that the hot metal temperature was constant.

FIG. 6 is a graph showing the transition of the reducing agent ratio in each period in the examples. In FIG. 6, the horizontal axis is the period and the vertical axis is the reducing agent ratio (kg / t). The unit kg / t of the reducing agent ratio is the mass (kg) of the reducing agent used to produce 1 ton of hot metal. The plots shown in FIG. 6 are also average values for one week.

As shown in FIG. 6, the average reducing material ratio during the period of Comparative Example 1 was 521 kg / t, whereas the average reducing material ratio during the period of Comparative Example 2 was 509 kg / t, which is the average of the periods of the invention examples. The reducing material ratio was 503 kg / t. As described above, the ratio of the reducing agent was lower in Comparative Example 2 and the invention example in which ferro-coke was used than in Comparative Example 1 in which ferro-coke was not used. This is considered to be due to the reduction improving effect of ferro-coke. Further, in the invention example, the reducing agent ratio was further lower than that of Comparative Example 2 by 6 kg / t.

FIG. 7 is a graph showing _{the average η CO} for each period in the examples. In FIG. 7, the vertical axis is η _CO (%) and the horizontal axis is a dimensionless radius (−). Here, the dimensionless radius is a value obtained by dividing the length of the blast furnace from the furnace center in the radial direction by the blast furnace radius. In addition, (-) indicates dimensionless.

FIG. 8 is a graph showing _{the average η H2} for each period in the examples. In FIG. 8, the vertical axis is η _H2 (%) and the horizontal axis is a dimensionless radius (−).

FIG. 9 is a graph showing the shift equilibrium temperature for each period in the examples. In FIG. 9, the vertical axis is the shift equilibrium temperature (° C.) and the horizontal axis is the dimensionless radius (−). As shown in FIG. 9, the shift equilibrium temperature during the period of Comparative Example 1 was constant at about 750 ° C. regardless of the radial direction. The shift equilibrium temperature during the period of Comparative Example 2 and Invention Example was lower than that of Comparative Example 1.

FIG. 10 is a graph showing the mixing ratio of ferro-coke at a plurality of positions in the radial direction in Comparative Example 2. In FIG. 10, the vertical axis is the mixing ratio of ferro-coke (kg / t), and the horizontal axis is the dimensionless radius. The circled plot in FIG. 10 shows the average value of the ferro-coke mixing ratio during the period, and the error bars indicate the standard deviation during the period.

FIG. 11 is a graph showing the mixing ratio of ferro-coke at a plurality of positions in the radial direction in the invention example. In FIG. 11, the vertical axis is the mixing ratio of ferrocokes (kg / t), and the horizontal axis is the dimensionless radius. The Δ plot in FIG. 11 shows the mean value during the period, and the error bars show the standard deviation during the period.

As can be seen from FIGS. 10 and 11, it can be seen that in the invention example, the fluctuation of the mixing ratio of ferro-coke can be suppressed as compared with the comparative example 2. The large fluctuation in the mixing ratio of ferro-coke in Comparative Example 2 is due to the fact that the particle size of the supplied ore fluctuates during operation and the degree of particle size segregation due to the difference in particle size between ferro-coke and ore changes. It is considered to be one of. That is, when the ore particle size is increased, the particle size difference between the ore and the ferrocokes is reduced and the particle size segregation is suppressed, while when the ore particle size is decreased, the particles of the ore and the ferrocokes are suppressed. Since the diameter difference is widened and particle size segregation is likely to occur, the mixing ratio of ferrocokes in the central portion and the peripheral portion is increased.

On the other hand, in the invention examples, the CO gas utilization and H ₂ gas utilization rate was measured using the established gas samplers into the blast furnace, with utilization and the formulas of these gases (5) to (7) radius Measure the mixing ratio of ferrocokes at 7 points in the direction, and adjust the charging method of ore and ferrocokes so that these mixing ratios have the initially set target ferrocokes mixing ratio distribution. bottom. As a result, the variation in the mixing ratio of ferro-coke was smaller in the invention example than in the comparative example 2. As a result, the fluctuation of the reducing agent ratio was suppressed, and the reducing agent ratio was reduced as compared with Comparative Example 2.

10 Blast Furnace 12 Gas Sampler 14 Ore Hopper 16 Ferrocoke Hopper 18 Belt Conveyor 20 Ore 22 Ferrocoke 24 Furnace Top Bunker 26 Bellless Chute

Claims (3)

A blast furnace, charged with coke, and ore ferro coke is mixed alternately,
It is a method of calculating the mixing ratio of ferrocoke in the ore layer among the coke layer and the ore layer alternately formed in the blast furnace.
At least one of CO gas utilization and H ₂ gas utilization rate of the furnace gas and the top gas of the blast furnace is measured,
The CO gas utilization and H seek shift equilibrium temperature with ₂ gas utilization rate, to calculate the mixing ratio of the ferro coke of the ore layer using the correlation between the shift equilibrium temperature and mixing ratio of the ferro coke, ferro How to calculate the mixing ratio of coke. Using at least one of CO gas utilization rate and H ₂ gas utilization rate of the furnace gas and the top gas at a plurality of positions in the radial direction of said blast furnace, calculates the mixing ratio of the ferro coke ore layer in said plurality of positions , The method for calculating the mixing ratio of ferro-coke according to claim 1. And coke, a blast furnace operation method of charging the ore ferro coke is mixed, alternately,
Charge of the ore and the ferrocoke so that the mixing ratio of the ferrocoke in the ore layer at the plurality of positions calculated by the method for calculating the mixing ratio of the ferrocoke according to claim 2 becomes a predetermined mixing ratio. Blast furnace operation method to adjust the method.

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