JP2022152721A - Operation method of blast furnace - Google Patents

Abstract

To provide an operation method of a blast furnace that enables proper furnace heat management at start-up after banking of the blast furnace.SOLUTION: An operation method of a blast furnace sets in advance a target numerical condition of a volume evaluation value to evaluate a volume of a SiO gas generation area formed around a raceway, and at least one of a hot metal Si concentration or a hot metal extraction ratio is adjusted so that the volume evaluation value satisfies the target numerical condition.SELECTED DRAWING: Figure 3

Description

The present invention relates to a method of operating a blast furnace during start-up after banking of the blast furnace.

In blast furnace operation, furnace heat management is important. Furnace heat management during start-up after blast furnace banking (stopping the air flow to the blast furnace while leaving the residue in the furnace as it is and suspending it in a state where it can be restarted) is the key to achieving stable blast furnace operation. is particularly important from the viewpoint of

Conventionally, hot metal temperature has been widely used as a furnace heat control index. Patent Document 1 discloses a furnace heat system that measures the temperature of hot metal during tapping with high accuracy using an optical fiber covered with a metal tube, and estimates the furnace heat level and furnace heat transition based on this temperature information. A control method is disclosed.

JP-A-11-222610

Here, generally, when the blast furnace is started up after banking, the work of scraping out the residue in the furnace is performed. However, it is difficult to completely remove the residue in the furnace, and usually the furnace is started up with residual iron lumps remaining at the bottom of the furnace.

High-temperature hot metal produced by a reduction reaction with coke and furnace gas drips onto the residual pig-metal lump at the bottom of the furnace, and the residual pig-metal lump may be dissolved. In this case, the heat of the hot metal is used as the heat of dissolution of the lump of residual pig iron, so the temperature of the hot metal drops. On the other hand, the residual iron lumps on the bottom of the furnace may not be melted by the molten iron. almost no decrease. In this way, since the molten iron temperature fluctuates according to the amount of molten iron ingot, it is difficult to use the molten iron temperature as a furnace heat management index when starting up the blast furnace after banking. .

In view of the above points, it is an object of the present invention to provide a blast furnace operating method capable of appropriately performing furnace heat management at the time of start-up after banking of the blast furnace.

In order to solve the above problems, the blast furnace operating method according to the present invention includes: (1) presetting a target numerical condition for a volume evaluation value for evaluating the volume of the SiO gas generation region formed around the raceway, A method of operating a blast furnace, wherein at least one of the Si concentration of hot metal and the tapping ratio is adjusted so that the volume evaluation value satisfies the target numerical condition.

(2) The setting of the target numerical conditions includes a relationship defining step for defining the relationship between the tapping ratio and the Si concentration of hot metal, which varies depending on the volume evaluation value, for each volume evaluation value, and a target numerical condition setting step of setting the target numerical conditions based on the relationship between the ratio and the molten iron Si concentration and the past blast furnace operation results. method of operation.

(3) The method of operating a blast furnace according to (1) or (2), characterized in that, as the blast furnace operation, an operational action is taken to improve the target numerical condition when the target numerical condition is not satisfied.

ADVANTAGE OF THE INVENTION According to this invention, since the furnace heat can be appropriately managed at the time of start-up after banking of a blast furnace, rapid and stable start-up operation after banking can be realized.

1 is a schematic diagram of a blast furnace that is an embodiment of the present invention; FIG. 2 is an enlarged view of the vicinity of a tuyere 2 in FIG. 1. FIG. 4 is a flow chart showing an operation method at the time of start-up after banking of the blast furnace in the present embodiment. 4 is a flow chart showing a procedure for creating a graph showing the relationship between the tapping ratio and the Si concentration of hot metal. 4 is a graph showing the relationship between the tapping ratio and the Si concentration of hot metal. FIG. 10 is an example of a graph showing the relationship between the tapping ratio and the Si concentration of hot metal obtained in step 101, and plotting a plurality of past blast furnace operation results in which the start-up after banking was good. .

<About the blast furnace>
FIG. 1 is a schematic diagram of a blast furnace that is one embodiment of the present invention. A blast furnace 1 is a bell-less blast furnace, and includes a tuyere 2 , an annular tube 3 , a blow pipe 4 , a pulverized coal injection lance 5 , a turning chute 6 , and a taphole 7 .

The tuyere 2 is a blowing port for blowing hot air generated in a hot blast furnace (not shown) into the blast furnace 1, and is provided in plurality in the lower part of the blast furnace 1 along the furnace circumferential direction.

The annular pipe 3 is arranged so as to surround the lower part of the blast furnace 1 . A plurality of blow pipes 4 are intermittently provided in the annular pipe 3 in the circumferential direction. The annular pipe 3 supplies the blow pipe 4 with hot air sent from a hot air furnace.

Each blowpipe 4 is connected to the annular tube 3 and each connected to a different tuyere 2 . The blow pipe 4 blows the hot air sent from the annular tube 3 into the blast furnace 1 through the tuyeres 2 .

The temperature of the hot air blown into the furnace is adjusted by controlling the heat storage amount and hot air supply amount in the hot air furnace. In addition, the content of oxygen contained in hot air can be adjusted by mixing air and oxygen in a hot air furnace. The moisture content of the hot air can be adjusted by dehumidifying or humidifying the hot air before it is blown into the blast furnace 1 from the hot air furnace.

A pulverized coal injection lance 5 injects pulverized coal into the blow pipe 4 . The pulverized coal blowing lance 5 is inserted through each blow pipe 4 , and the tip of the pulverized coal blowing lance 5 extends inside each blow pipe 4 . Pulverized coal blown from the pulverized coal injection lance 5 is blown into the blast furnace 1 together with hot air passing through the blow pipe 4 .

The turning chute 6 rotates around an axis extending in the vertical direction, and loads the ore layer forming raw material and the coke layer forming raw material as blast furnace raw materials so that the ore layer and the coke layer are alternately formed in layers in the furnace. enter. Sintered ore, pellets, lump ore, and non-calcined coal-containing agglomerate ore can be used as the ore layer forming raw material. The ore layer forming raw materials may also include things other than ores (for example, reducing aids such as nodule coke). The coke layer forming raw material may contain ferro coke. By controlling the inclination angle and rotation speed of the revolving chute 6, the blast furnace raw material can be charged at a desired position.

The taphole 7 is provided at the bottom of the blast furnace 1 and taps hot metal produced by reduction of the ore layer forming raw material. A plurality of tap holes 7 are provided along the circumferential direction of the furnace, and molten iron can be tapped continuously or intermittently.

FIG. 2 is an enlarged view of the vicinity of the tuyere 2 in FIG. Referring to FIG. 2, a combustion space (raceway 10) is formed in the furnace by the wind pressure of hot air blown into the furnace from tuyeres 2. As shown in FIG. Inside the raceway 10, the coke particles swirl and burn to reduce the ore. Also, a SiO gas generation region 100 is formed as a coke filling layer so as to surround the raceway 10 . In the SiO gas generation region 100, a high-temperature reaction occurs in which SiO gas and carbon monoxide are generated by the reaction of C and SiO ₂ contained in the coke layer forming raw material (see formula (1) below for the reaction formula).

The inventors have found that rapid and stable start-up operation is possible by controlling the furnace heat at the time of start-up after blast furnace banking based on the volume of the SiO gas generation region 100 . Here, at the start-up after blast furnace banking, the position of the cohesive zone (see FIG. 1) formed in the blast furnace 1 is high. Therefore, most of the SiO 2 gas generated in the SiO gas generating region 100 is absorbed by the dropping hot metal. From this, it is considered that the hot metal Si concentration (%) is a process defined by the generation rate of SiO gas, that is, the rate of SiO gas generation is determined (see Nippon Steel Engineering No. 413, pp. 123-129). The volume of the SiO gas generation region 100 is appropriately controlled by controlling the relationship between the tapping ratio theoretically derived from this generation rate control and the Si concentration (%) of the molten iron (hereinafter also referred to as the molten iron Si concentration). be able to.

In view of these points, the present inventor set in advance the target numerical conditions for the evaluation value for evaluating the volume of the SiO gas generation region 100 (hereinafter referred to as the volume evaluation value), and then set the tapping ratio and the molten iron Si concentration is used as an operational management index, and at least one of the tapping ratio and hot metal Si concentration is adjusted so that the volume evaluation value satisfies the target numerical conditions at the time of start-up after blast furnace banking. , it was found that a rapid and stable start-up is possible. It should be noted that "Adjust the hot metal Si concentration so that the volume evaluation value satisfies the target numerical conditions" means that the appropriate conditions for the hot metal Si concentration are determined based on the tapping ratio and the target numerical conditions for the volume evaluation value. It refers to determining and adjusting the hot metal Si concentration so as to satisfy the appropriate conditions. In addition, "Adjust the tapping ratio so that the volume evaluation value satisfies the target numerical conditions" means that the appropriate conditions for the tapping ratio are adjusted based on the hot metal Si concentration and the target numerical conditions for the volume evaluation value. It refers to adjusting the tapping ratio so as to determine the appropriate conditions and satisfy the appropriate conditions.

Hereinafter, a method of operating a blast furnace at the time of start-up after banking of the blast furnace based on the above findings will be described with reference to the flowchart of FIG. FIG. 3 is a flow chart showing an operation method at the time of start-up after banking of the blast furnace in this embodiment. Steps 101 and 102 are carried out in advance before starting up the blast furnace after banking. Note that "at the time of start-up" refers to the period from restarting the blast furnace (resuming hot air blowing) until the tapping ratio of the blast furnace during normal operation is achieved.

<Step 101>
First, a graph that defines the relationship between the tapping ratio and the Si concentration of hot metal is created based on the generation rate-determining theory (step 101). The procedure for creating this graph will be described in more detail with reference to the flowchart shown in FIG.

As mentioned above, when starting up after blast furnace banking, the position of the cohesive zone (see Fig. 1) formed in the blast furnace 1 is high, so the hot metal Si concentration (%) is considered to follow the rate-limiting SiO gas generation. can be regarded as A reaction in the SiO gas generation region 100 can be defined by the following equation (1). In addition, "SiO(g)" in Formula (1) is SiO gas.
_SiO2 +C=SiO(g)+CO (1)
The positive reaction rate (reaction rate for generating SiO gas) in formula (1) is calculated by the following reaction rate formula.
_R1 = _k1.CSiO2 ( ₂ )
where R ₁ is the positive reaction rate (mol/(cm ³ s)), k ₁ is the reaction rate constant (s ⁻¹ ), C _SiO2 is the concentration of SiO ₂ with respect to the volume of the SiO gas generation region 100 (mol/ cm ³ ), which can be calculated from the properties of the coke charged into the top bunker. k ₁ is calculated by the following formula.
k1=2.0 _× 104・exp( ^-69000 /RT) (3)
where T is the absolute temperature of hot metal (K) and R is the gas constant (cal/(mol K)).

In advance, (A) the value of the hot metal temperature (corresponding to T described above) and (B) the SiO gas generation region index V _SiO (m ³ ), which indicates the volume of the SiO gas generation region 100 with respect to the blast furnace volume V _f (m ³ ) ) and set the value of the volume ratio D (%). That is, in this embodiment, the volume ratio D (%) is used as the volume evaluation value. Here, since the volume of the blast furnace to be started up is known, the SiO gas generation area index V _SiO is calculated by multiplying the set volume ratio D by the blast furnace volume _Vf (step 101a).

The reaction rate constant k ₁ (s ⁻¹ ) is calculated by substituting the preset hot metal temperature T into the above equation (3) (step 101b).

By substituting k ₁ calculated in step 101b and C _SiO2 calculated in advance into the above equation (2), the forward reaction rate R ₁ (mol/(cm ³ s)) is calculated. (step 101c).

R ₁ (mol/(cm ³ s) is multiplied by the SiO gas generation area index V _SiO calculated in step 101a and the value converted from 1 day to seconds (86400 (s)). _SiO (mol/d), the number of mols of SiO gas generated in , is calculated (step 101d).

Here, assuming that all of the SiO gas generated per unit time and unit volume has migrated to Si in the hot metal, the number of moles of Si in n _SiO calculated in step 101d is multiplied by the atomic weight of Si to convert the unit. Thus, the mass m _Si (t/d) of Si contained in the hot metal per day is calculated (step 101e).

The hot metal Si concentration (%) is calculated by dividing m _Si (t/d) calculated in step 101e by the amount of tapped iron per day (t/d) (step 101f). Further, by dividing the amount of tapped iron per day (t/d) by the blast furnace volume V _f (m ³ ), the tapped iron ratio (t/d/m ³ ) is calculated (step 101g).

Based on the hot metal Si concentration (%) calculated in step 101f and the tapping ratio (t/d/m ³ ) calculated in step 101g, the relationship between the tapping ratio and the hot metal Si concentration is defined. A graph is created (step 101h). In step 102, which will be described later, it is necessary to select the optimum volume ratio D from a plurality of volume ratios D. Therefore, in step 101, it is necessary to create a graph for each of the plurality of predetermined volume ratios D. . These multiple volume ratios D can be set, for example, in a range of 1% to 10% at intervals of 1% based on actual operational results.

FIG. 5 shows a graph defining the relationship between the tapping ratio and the hot metal Si concentration, which was created in steps 101a to 101h described above. In the graph of FIG. 5, the hot metal temperature T is set to 1510° C., and the volume ratio D (%) of the SiO gas generation region index V _SiO (m ³ ) to the blast furnace volume V _f (m ³ ) is 2% and 6%, respectively. and when the hot metal temperature T is set to 1530 ° C., and the volume ratio D (%) of the SiO gas generation region index V _SiO (m ³ ) to the blast furnace volume V _f (m ³ ) is 2% and 6%, respectively. And if you do, it shows. In FIG. 5, only graphs with a volume ratio D of 2% and 6% are created, but as described above, graphs with other criteria (for example, 1% intervals in the range of 1% to 10%) may be created. Incidentally, when the volume ratio D increases, the Si concentration of hot metal inevitably increases for the same tapping ratio.

From FIG. 5, it can be seen that when the hot metal temperature T and the volume ratio D are constant, the tapping ratio and the hot metal Si concentration are inversely proportional, and the slope increases as the tapping ratio decreases. Therefore, when the tapping ratio is low, such as immediately after the blast furnace is restarted after banking, the Si concentration in hot metal is strongly affected by the tapping ratio. On the other hand, it can be seen from FIG. 5 that the hot metal Si concentration is not easily affected by the hot metal temperature. In view of these points, the present inventors set the tapping ratio and molten iron Si concentration as operational management indicators, and based on these, the volume of the SiO gas generation region 100 is controlled to achieve appropriate furnace heat management. I found out.

<Step 102>
Next, referring again to FIG. A target numerical condition is set so that the increase is favorable (step 102). The four graphs shown in FIG. 6 are obtained by theoretically deriving the relationship between the tapping ratio and the Si concentration of hot metal according to the procedure of step 101, and graphing the relationship. The preset volume ratios D (%) are 2%, 2.5%, 4% and 6%, respectively, and the preset hot metal temperatures are all 1530°C.

Of the past blast furnace operation results, the good operation data that started well after banking was plotted on this graph, and the two graphs drawn at the position sandwiching the area where these good operation data are concentrated are plotted. A target numerical condition for the volume ratio D (%) can be set based on the volume ratio D (%) (this setting method is hereinafter referred to as setting method A). In the illustrated example, when the tapping ratio is 0.5 or more and less than 1.2, the good operation data are concentrated in the region sandwiched between the D: 4% graph and the D: 6% graph. Therefore, when the tapping ratio is 0.5 or more and less than 1.2, it is desirable to set the target numerical condition for the volume ratio D (%) to 4% or more and 6% or less. When the tapping ratio is 1.2 or more and less than 1.5, the good operation data are concentrated in the region sandwiched between the D: 2% graph and the D: 4% graph. Therefore, when the tapping ratio is 1.2 or more and less than 1.5, it is desirable to set the target numerical condition of the volume ratio D (%) to 2% or more and 4% or less. When the tapping ratio is 1.5 or more and less than 2.0, the good operation data are concentrated in the region sandwiched between the D: 2% graph and the D: 2.5% graph. Therefore, when the tapping ratio is 1.5 or more and less than 2.0, it is desirable to set the target numerical condition for the volume ratio D (%) to 2% or more and 2.5% or less. As shown in FIG. 6, once the target numerical conditions are determined, the relationship between the corresponding hot metal Si concentration and tapping ratio can also be grasped.

In this embodiment, the target numerical value condition for the volume ratio D (%) is set by the setting method A described above, but the setting method is not limited to this. For example, based on the plot of good operation data in which the start-up after banking was good among the past blast furnace operation results, the volume ratio over the entire tapping ratio (0.5 or more and less than 1.5) The target numerical value condition may be set so that the target numerical value condition for D (%) changes continuously (this setting method is hereinafter referred to as setting method B). A region S that satisfies the target numerical value conditions set by the setting method B is indicated by hatching in FIG. Here, "the target numerical condition changes continuously" means that the target numerical condition as the left limit of the arbitrary tapping ratio and the target numerical condition as the right limit of the arbitrary tapping ratio It shall refer to matching. The “target numerical condition as the left limit of an arbitrary tapping ratio” means that the tapping ratio reaches the arbitrary tapping ratio along the direction of the arrow X shown in FIG. It refers to the target numerical condition when The “target numerical condition as the right limit of an arbitrary tapping ratio” means that the tapping ratio reaches the arbitrary tapping ratio along the direction of arrow Y shown in FIG. It refers to the target numerical condition when

When setting method A is adopted, the target numerical conditions change discontinuously around the tapping ratio of 1.2. On the other hand, in setting method B, the target numerical conditions change continuously over the entire tapping ratio (0.5 or more and less than 1.5) at the time of start-up. Therefore, according to setting method B, even if the tapping ratio changes as the start-up progresses, significant improvement action (see step 105 described later) is not required, and more stable blast furnace operation can be performed.

Also, for example, when the tapping ratio is 1.5 or more and less than 2.0, it can be seen that the good operation data are concentrated around the graph of D: 2%, so the target value for the volume ratio D (%) The condition may be set at about 2%.

FIG. 6 is only an example in the present invention, and the target numerical conditions set in the present invention are not limited to the above-described target numerical conditions. That is, the target numerical conditions are not limited to the ranges described above because the graph in FIG. 6 changes depending on the properties of the coke used. Also, the target numerical value condition can be a target value (one value) instead of a range.

<Step 103>
Next, the blast furnace is newly started up after banking, and the tapping ratio (t/d/m ³ ) and the hot metal Si concentration (%) are calculated as operational control indices (step 103). Since the iron output ratio is roughly proportional to the volume of hot air blown into the blast furnace 1 through the annular tube 3 → blow pipe 4 → tuyere 2, the iron output ratio can be estimated by measuring the volume of hot air. can be done. The Si concentration of hot metal can be calculated by component analysis of the Si concentration of hot metal tapped from the tap hole 7 of the blast furnace 1 . The method for calculating the tapping ratio (t/d/m ³ ) and the hot metal Si concentration (%) is not limited to the above method, and various known methods can be employed.

<Steps 104, 105>
Based on the tapping ratio (t/d/m ³ ) calculated in step 103 and the target numerical conditions set in step 102, an appropriate condition for the hot metal Si concentration (%) is determined. It is determined whether or not the calculated hot metal Si concentration (%) satisfies the appropriate conditions (step 104). If the molten iron Si concentration (%) calculated in step 103 satisfies the appropriate conditions (step 104 Yes), it is determined that "startup after banking is good", and furnace heat management is terminated. On the other hand, if the hot metal Si concentration (%) calculated in step 103 does not satisfy the appropriate conditions (step 104 No), it is determined that "the start-up after banking is unsatisfactory", and the hot metal Si concentration is adjusted. Take remedial action (step 105).

The determination of step 104 and the improvement action of step 105 will be described below with reference to FIG. As an illustration, the calculation results of step 103 are plotted as circled points A and circled points B in FIG.

When the calculation result of step 103 is point A in FIG. 6, the hot metal Si Determine the appropriate concentration conditions (1.8% to 2.8%). Since the hot metal Si concentration (4.0%) at point A is higher than the upper limit (2.8%) of the appropriate conditions, the hot metal Si concentration is lowered while maintaining the tapping ratio to achieve the appropriate conditions for the hot metal Si concentration. Take improvement actions to satisfy (1.8% to 2.8%). As an improvement action, an action to reduce the heat in the blast furnace 1 (increase blast moisture content, decrease RAR, decrease PCR, etc.) is performed.

When the calculation result of step 103 is the point B in FIG. 6, the hot metal Si Determine the appropriate concentration conditions (3.4% to 5.0%). Since the hot metal Si concentration (3.0%) at point B is lower than the lower limit (3.4%) of the appropriate conditions, the hot metal Si concentration is increased while maintaining the tapping ratio to achieve the appropriate conditions for the hot metal Si concentration. Take improvement actions to satisfy (3.4% to 5.0%). As an improvement action, an action to increase the heat in the blast furnace 1 (reduce blast moisture content, increase RAR, increase PCR, etc.) is performed.

After implementing the improvement action (step 105) as described above, the tapping ratio (t/d/m ³ ) and hot metal Si concentration (%) are calculated again (step 103), and the calculated hot metal Si concentration ( %) satisfies the proper condition (step 104).

(Example)
Blast Furnace 1 of A Steelworks was started up from banking. The setting method B described above was adopted, the area S shown in FIG. 6 was set as the target numerical condition, and the furnace heat was managed using the relationship between the tapping ratio and the Si concentration of the hot metal as an operational management index.

During the start-up process of blast furnace 1, the Si concentration in hot metal was 4.2 (%) when the tapping ratio was 0.77 (t/d/m ³ ) (see point C in FIG. 6). On the other hand, in region S shown in FIG. 6, when the tapping ratio is 0.77 (t/d/m ³ ), the appropriate conditions for the hot metal Si concentration (%) are determined to be 2.5% to 4.0%. rice field. Therefore, improvement actions were taken to lower the hot metal Si concentration while maintaining the tapping ratio and to satisfy the appropriate conditions (2.5% to 4.0%) for the hot metal Si concentration. As an improvement action, an action was taken to increase the blast moisture content from 30 (g/Nm ³ ) to 34 (g/Nm ³ ). As a result, the molten iron Si concentration (%) was reduced to 3.0%, satisfying the appropriate conditions.

In another start-up process of blast furnace 1, the Si concentration in hot metal was 2.95 (%) when the tapping ratio was 1.06 (t/d/m ³ ) (see point D in Fig. 6). On the other hand, in region S shown in FIG. 6, when the tapping ratio is 1.06 (t/d/m ³ ), the appropriate conditions for the hot metal Si concentration (%) are determined to be 1.4% to 2.6%. rice field. Therefore, improvement actions were taken to lower the hot metal Si concentration while maintaining the tapping ratio and to satisfy the appropriate conditions (1.4% to 2.6%) for the hot metal Si concentration. As an improvement action, an action was taken to lower the PCR from 80 (kg/t) to 77 (kg/t). As a result, the hot metal Si concentration (%) decreased to 2.5%, satisfying the appropriate conditions.

As in the above-described embodiment, as a result of proceeding with the start-up of the blast furnace after banking with the blast furnace operating method according to the present invention, in the start-up process, the furnace hangs due to excessive furnace heat and slag discharge failure due to the decrease in furnace heat. We were able to complete the start-up quickly and stably without any trouble.

(Modification)
In the above-described embodiment, in step 101, a graph was created to define the relationship between the tapping ratio and the hot metal Si concentration, but the method for defining the relationship between the tapping ratio and the hot metal Si concentration is not limited to this. A data table such as a table may be created.

(Modification)
In the above-described embodiment, in step 104, based on the tapping ratio (t/d/m ³ ) calculated in step 103 and the target numerical conditions set in step 102, the hot metal Si concentration (%) was determined, and it was determined whether or not the molten iron Si concentration (%) calculated in step 103 satisfies the appropriate conditions. However, the present invention is not limited to this, and based on the hot metal Si concentration (%) calculated in step 103 and the target numerical conditions set in step 102, the appropriate conditions for the tapping ratio (t/d/m ³ ) and determining whether or not the tapping ratio (t/d/m ³ ) calculated in step 103 satisfies the appropriate condition. In this case, in step 105, an improvement action is taken to adjust the tapping ratio so as to satisfy the appropriate conditions. A case of taking an improvement action to adjust the tapping ratio will be described below with reference to FIGS. 3 and 6 again. Setting method A is adopted for setting the target numerical value conditions for the volume ratio D (%).

When the calculation result of step 103 is point A in FIG. Appropriate conditions for iron ratio (0.5 to 0.8) are determined. Since the tapping ratio at point A (1.1) is higher than the upper limit (0.8) of the appropriate range, the tapping ratio is lowered while maintaining the hot metal Si concentration to achieve the appropriate tapping ratio condition (0 .5 to 0.8) are satisfied. As an improvement action, for example, an action of reducing the amount of blown air is performed. When the tapping ratio is lowered while maintaining the hot metal Si concentration at point A to satisfy the appropriate tapping ratio condition (0.5 to 0.8), for example, the air flow rate is changed from 3000 ( ^Nm3 /min) to 2950 (Nm ³ /min).

When the calculation result of step 103 is point B in FIG. Determine the proper conditions for the iron ratio (0.7 to 1.0). Since the tapping ratio at point B (0.6) is lower than the lower limit (0.7) of the appropriate range, the tapping ratio is increased while maintaining the hot metal Si concentration to achieve the appropriate tapping ratio condition (0 .7-1.0) to take improvement actions. As an improvement action, for example, an action of increasing the air flow rate is performed. When the tapping ratio is increased while maintaining the hot metal Si concentration at point B to satisfy the appropriate tapping ratio condition (0.7 to 1.0), for example, the air flow rate is changed from 1600 ⁽ Nm (Nm ³ /min).

Furthermore, as another method of step 104, based on the tapping ratio (t/d/m ³ ) and hot metal Si concentration (%) calculated in step 103 and the target numerical conditions set in step 102, , appropriate conditions for the tapping ratio (t/d/m ³ ) and hot metal Si concentration (%) are determined, respectively, and the tapping ratio (t/d/m ³ ) and hot metal Si concentration (% ) satisfies each appropriate condition. In this case, in step 105, an improvement action is taken to adjust the tapping ratio so as to satisfy the proper condition of the tapping ratio (t/d/m ³ ), and the proper condition of the hot metal Si concentration (%) is satisfied. An improvement action may be taken to adjust the hot metal Si concentration, or an improvement action capable of adjusting both the tapping ratio and the hot metal Si concentration may be taken.

(Modification)
In the above-described embodiment, the volume evaluation value for evaluating the volume of the SiO gas generation region 100 is the SiO gas generation region index V _SiO (m ³ ), which indicates the volume of the SiO gas generation region 100 with respect to the blast furnace volume V _f (m ³ ). was used, but the present invention is not limited to this. For example, the volume (m ³ ) of the SiO gas generation region 100 itself may be used as the volume evaluation value. The volume (m ³ ) of the SiO gas generation region 100 can be determined, for example, by measuring the temperature inside the blast furnace 1 with a sonde inserted into the blast furnace 1 from the outside, and based on the measurement result, the volume (m ³ ) of the SiO gas generation region 100 ) can be adopted.

1 Blast Furnace 2 Tuyere 3 Annular Pipe 4 Blow Pipe
5 lance for pulverized coal injection 6 turning chute 7 tap hole

Claims (3)

preset the target numerical conditions for the volume evaluation value for evaluating the volume of the SiO gas generation region formed around the raceway,
A method of operating a blast furnace, wherein at least one of the Si concentration of hot metal and the tapping ratio is adjusted so that the volume evaluation value satisfies the target numerical condition. The setting of the target numerical conditions is
a relationship defining step for defining the relationship between the tapping ratio and the Si concentration of hot metal, which varies depending on the volume evaluation value, for each volume evaluation value;
a target numerical condition setting step of setting target numerical conditions based on the relationship between the tapping ratio and the molten iron Si concentration obtained in the relationship defining step and past blast furnace operation results;
The method of operating a blast furnace according to claim 1, characterized in that it is performed by 3. The method of operating a blast furnace according to claim 1 or 2, wherein when the target numerical condition is not satisfied, an operational action for improving it is carried out as the blast furnace operation.

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