JP6602254B2 - Blast furnace resting method - Google Patents

Description

  The present invention relates to a blast furnace resting method for smoothly resuming a blast furnace in a resting state to a normal operating state.

In the operation of the blast furnace, a resting wind is periodically stopped to stop the hot air blown into the blast furnace, and the blast furnace facilities are repaired during the resting period, such as repairing the furnace body and repairing incidental facilities. When resting, the heat from the blast furnace is taken away by heat dissipation, so the furnace temperature in the blast furnace decreases with time. In order to adjust production, there may be a pause.
Then, when shifting the blast furnace in the resting state to normal operation, hot air is blown into the blast furnace in the resting state, and the temperature in the furnace is raised in a short period to return to the normal operating state. Is implemented.

As a technique for restarting the operation of the blast furnace smoothly by implementing a blast furnace start-up, there are those disclosed in Patent Documents 1 to 3.
Patent document 1 aims at preventing the discharge failure of the slag at the initial stage of the rest wind start (at the time of low temperature).
Specifically, the hot metal temperature immediately before entering the blast furnace is estimated, hot metal Si is estimated from the hot metal temperature, and the amount of meteorite (SiO ₂ ) is adjusted accordingly to suppress the increase in slag basicity. The purpose is to prevent poor slag discharge at the beginning of the wind (at low temperatures).

Patent Document 2 describes that in a blast furnace where pulverized coal blowing operation is performed, the furnace condition failure or instability phenomenon such as slip, shelf suspending, blow-through, etc. that occurs immediately after resuming air blowing after resting is eliminated, and startup by resuming air blowing The purpose is to make it possible to perform smoothly in a short time.
Specifically, by reducing the amount of pulverized coal injection before entering the resting wind and increasing the amount of coke added to the top of the furnace according to the decrease, thereby appropriately controlling the heat flow ratio during the resting wind, It is possible to suppress an undesirable increase in the softened cohesive zone at the start of resumption of air blowing, and as a result, normal operating conditions can be achieved in a short time without causing deterioration of furnace conditions such as slip, shelf hanging, and blow-through. The purpose is to recover.

Patent Document 3 aims to smoothly start up a blast furnace after performing blast furnace reduction operation and performing in-furnace repair.
Specifically, after performing the blast furnace scale-down operation, the blast furnace whose temperature in the furnace has greatly decreased due to a long period of off-air is maintained and the flow of the soot in the hearth is maintained well, so that it can be smoothly re-started. The purpose is to launch.

JP 2013-256698 A Japanese Patent No. 3465471 Japanese Patent No. 3832451

However, if the in-furnace temperature of the blast furnace is excessively lowered during the resting wind, the hot metal in the furnace is solidified, and there is a possibility that defective hot metal discharge that becomes an obstacle when the resting wind is started up may occur. As described above, when defective hot metal discharge occurs, the air permeability in the furnace deteriorates. Moreover, there exists a possibility that the ventilation volume of the hot air which blows in into a blast furnace may reduce with the deterioration of the air permeability in a furnace.
However, Patent Document 1 is a technique that focuses only on the adjustment of the basicity of the slag component, and does not specify the adjustment of (Al ₂ O ₃ )% in the slag that is required for suppressing solidification. Therefore, it is considered that slag with which hot metal discharge is good cannot always be obtained.

Patent Document 2 is a technology that makes it possible to smoothly start up a resting wind in a short time. Although it seems to be good with respect to the discharge of slag from the blast furnace, it is clearly described in the same document. The details of slag discharge are unknown.
Since patent document 3 is not estimating Si density | concentration in hot metal, it is thought that it cannot adjust to the target slag component. Therefore, the Si concentration in the hot metal is increased, the slag basicity is increased, the slag viscosity and the like are increased, and there is a possibility that the slag discharge failure at the initial stage of the rest wind start (at low temperature) may occur.

  Accordingly, the present invention has been made in view of the above-described problems, and avoids the occurrence of defective hot metal discharge at the time of blast furnace blast start-up, so that blast furnace operation can be resumed smoothly. The purpose is to provide a wind method.

In order to achieve the above-described object, the present invention takes the following technical means.
According to the blast furnace air suspension method of the present invention, the hot metal temperature before the air break, the hot metal temperature after the start of the air break, and the slope of the hot metal temperature decrease between the air break start time and the air break start time from the air break time. Is obtained in advance, and the relationship between the reduced material ratio increase before the resting wind and the slope of the hot metal temperature decrease during the start of the resting wind from before the resting is obtained in advance. the discharge condition of put that soluble Zukukasu wind startup, the discharge good data of the hot metal debris to stratify in the discharge failure data of the hot metal debris, from the discharge data of the molten iron slag which is stratified, the deactivation The lower limit temperature of the hot metal at which the hot metal discharge state at the wind start-up becomes good is obtained in advance, and the amount of reduction material ratio increase before the resting of the hot metal and The relationship with the maximum value of Si] (mass% concentration) is obtained in advance, and the rest Wherein the wind rising hot metal slag discharge condition is good and Do away lag basicity (CaO (wt% concentration) / SiO ₂ (wt% concentration)), and slag (Al ₂ O ₃₎ (mass% concentration ) In advance, and then, based on the relationship between the reducing material ratio increase amount and the slope of the hot metal temperature decrease, the hot air time, and the hot metal temperature before the hot air break, The amount of increase in the reducing material ratio is determined so that the hot metal temperature at the time of start-up does not fall below the lower limit temperature of the hot metal determined in advance, and the hot metal temperature at the time of start-up of the rest air does not fall below the lower limit temperature of the hot metal From the reduced material ratio increase determined as described above, the maximum value of [Si] (mass% concentration) in the hot metal after the start of the rest wind is estimated, the estimated [Si] (mass%) in the hot metal the maximum value of the concentration), basicity of the slag (CaO (wt% concentration) / SiO ₂ (wt% concentration)), and slag (Al ₂ O ₃₎ (wt% concentration) Obtains an estimate, [Si] in the molten iron after the deactivation air rising at the maximum value of (mass% concentration), basicity of the slag (CaO (wt% concentration) / SiO ₂ (wt% concentration) ), And in the slag (Al ₂ O ₃ ) (mass% concentration) so as to satisfy the appropriate condition, determine the secondary material to be introduced into the blast furnace, the determined reducing material ratio increase amount and the secondary material, After putting into the blast furnace before the resting wind, the resting wind is performed, and then the resting wind is started to restart the operation of the blast furnace.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the defective discharge of the hot metal at the time of the blast furnace rest wind start-up can be avoided, and the operation of a blast furnace can be restarted smoothly.

It is the figure which showed transition of the ventilation flow volume of the hot air from before a rest wind to rest rest start-up. It is the figure which showed transition of the hot metal temperature from a wind break before to a wind break start-up. It is the figure which showed transition of the reductant ratio from before a rest wind to the rest wind rise. It is the figure which showed the relationship between the reducing material ratio increase amount before a rest period, and the inclination of hot metal temperature fall. It is the schematic which showed typically the flow of the hot metal after tapping. It is the figure which showed the relationship between a rest time and the hot metal temperature at the time of a rest wind start-up. It is the figure which showed the transition of [Si]% in the hot metal from before the wind break to after the wind break. It is the figure which showed the relationship between the reduction | restoration material ratio increase amount before a rest wind, and the maximum value of [Si]% in hot metal after a rest wind start-up. FIG. 3 is a diagram showing the relationship between slag basicity (C / S) and slag crystallization temperature. FIG. 4 is a graph showing the relationship between slag basicity (C / S) and slag viscosity. It is the schematic which showed typically the flow of the hot metal after tapping. FIG. 3 is a diagram showing the relationship between slag basicity (C / S) and slag crystallization temperature. FIG. 4 is a graph showing the relationship between slag basicity (C / S) and slag viscosity. FIG. 6 is a diagram showing the relationship between the amount of reduction material ratio increase and the maximum value of [Si]% in the hot metal after the start of rest wind. It is the figure which showed the change of slag basicity (C / S) by the change of [Si]% in hot metal. FIG. 3 is a diagram showing the relationship between slag basicity (C / S) and slag crystallization temperature. It is the figure which showed the relationship between the reducing material ratio increase amount before a rest period, and the inclination of hot metal temperature fall. It is the figure which showed the amount of reduction material ratio increase before a rest wind, and the maximum value of [Si]% in hot metal after a rest wind start-up. It is the figure which showed transition of the hot metal temperature from a wind break before to a wind break start-up. It is the figure which showed the relationship between the reducing material ratio increase amount before a rest period, and the inclination of hot metal temperature fall. It is the schematic which showed typically the flow of the hot metal after tapping. It is the figure which showed the relationship between a rest time and the hot metal temperature of a rest wind rise. It is the figure which showed the transition of [Si]% in the hot metal from before the wind break to after the wind break. It is the figure which showed the relationship between the reduction | restoration material ratio increase amount before a rest wind, and the maximum value of [Si]% in hot metal after a rest wind start-up. FIG. 3 is a diagram showing the relationship between slag basicity (C / S) and slag crystallization temperature. FIG. 4 is a graph showing the relationship between slag basicity (C / S) and slag viscosity. FIG. 3 is a diagram showing the relationship between slag basicity (C / S) and slag crystallization temperature. FIG. 4 is a graph showing the relationship between slag basicity (C / S) and slag viscosity. It is the figure which showed the relationship between the reduction | restoration material ratio increase amount before a rest wind, and the maximum value of [Si]% in hot metal after a rest wind start-up. It is the figure which showed the change of slag basicity by the change of [Si]% in hot metal. FIG. 3 is a diagram showing the relationship between slag basicity (C / S) and slag crystallization temperature. It is a flowchart figure of the blast furnace resting method concerning this invention.

Hereinafter, an embodiment of a blast furnace resting method according to the present invention will be described with reference to the drawings.
In addition, embodiment described below is an example which actualized this invention, Comprising: The structure of this invention is not limited with the specific example. Therefore, the technical scope of the present invention is not limited only to the contents disclosed in the present embodiment.
Moreover, in the following description, the same code | symbol is attached | subjected to the same components. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

First, the outline of the blast furnace resting method of this embodiment will be described.
The blast furnace air suspension method of the present embodiment is prepared in advance by arranging the following three relationships ((i) to (iii)) based on past past results of air suspension.
(i) The relationship between the amount of increase in the reducing material ratio related to the reducing material to be introduced into the hot metal in the blast furnace 1 and the slope of the decrease in hot metal temperature during the resting wind is obtained in advance.

(ii) It is determined whether the hot metal discharge state from the blast furnace 1 at the start of the rest wind is good or bad, and the lower limit temperature of the hot metal temperature at the start of the rest wind is obtained.
(iii) The relationship between the amount of reduction material ratio increase before the break and the maximum value of the [Si] concentration in the hot metal at the start of the break is obtained.
(iv) Using the above-mentioned relationship prepared in advance, obtain the following parameters between the start of the rest and the start of the rest.

(v) The amount of reducing material ratio increase before the break is determined so that the hot metal temperature at the start of the break is not lower than the lower limit temperature obtained in advance.
(vi) Estimate the amount of increase in [Si]% in hot metal at the start of rest time, corresponding to the determined reduction material ratio increase before rest time.
(vii) The amount of change in the slag component corresponding to the estimated increase in [Si]% in the hot metal is estimated.

(viii) Based on the estimated amount of change in the slag component, the component of the auxiliary raw material to be introduced into the blast furnace 1 is adjusted so that the hot metal discharge is good when the wind is stopped.
In this way, after the determined reducing material ratio increase (determined by (v)) and auxiliary material (determined by (viii)) are put into the blast furnace 1 before the resting wind, the resting wind is performed, and then the resting state is performed. Wind up and restart blast furnace 1 operation.

Next, the blast furnace air suspension method of the present embodiment will be described in detail. The data shown in the following (A1) to (A5) is an example of past results.
(A1)
Specifically, the slope of the hot metal temperature drop between before the wind break and between the start of the wind break is determined in advance from the hot metal temperature before the wind break, the hot metal temperature after the wind break rise, and the wind break time. This advance preparation procedure corresponds to the procedure (1) in FIG.

  Here, resting air refers to stopping hot air blown into the blast furnace 1 during normal operation. In addition, since heat is taken away from the blast furnace 1 by heat dissipation when the resting wind is implemented, the furnace temperature of the blast furnace 1 falls with time. The term “rest wind start-up” means that hot air is blown into the blast furnace 1 that is resting and normal operation is resumed. The resting time refers to the time from when hot air blowing is stopped in the blast furnace 1 to when hot air blowing is resumed.

In the present embodiment, during the rest period, hot air is not blown, and the temperature of the hot metal in the furnace is lowered. Therefore, the inclination of the hot metal temperature drop during that period is obtained in advance.
FIG. 1 shows the transition of the flow rate of hot air from before the break and after the start of the break.
The flow rate of hot air is the total of hot air blown from all tuyere provided in the blast furnace 1, and how many normal rice (Nm ³ / min) hot air is blown into the blast furnace 1 per minute. Point to.

As shown in FIG. 1, the flow rate of hot air during normal operation is about 6000 (Nm ³ / min). In addition, in FIG. 1, the average value of the ventilation flow volume for every hour is plotted. The numbers on the horizontal axis in FIG. 1 are dates, and show changes over a period of 10 days (1/17 to 1/27) including the rest. The time when the hot air flow rate is 0 plotted in FIG. 1 is the rest time.
FIG. 2 shows the transition of the hot metal temperature from before the wind break to after the wind break.

As shown in FIG. 2, during normal operation, the heat of combustion of the reducing material (coke, pulverized coal, etc.) and the heat of reduction of iron oxide and the heat dissipated from the top and furnace body are balanced. The hot metal temperature in the furnace is in the range of 1480 ℃ to 1540 ℃.
However, since the combustion of coke and pulverized coal stops during the rest period, the heat dissipated according to the rest period is lost, and the hot metal temperature in the furnace is lowered.

Therefore, the difference between the hot metal temperature measured in the furnace before the break and the hot metal temperature measured in the furnace after the start of the break, divided by the break time, The slope of the hot metal temperature drop during raising was taken as the slope.
(A2)
Subsequently, the relationship between the reducing material ratio increase before the break and the slope of the hot metal temperature drop in the furnace between the break and the start of the break determined in step (1) is obtained in advance. This advance preparation procedure corresponds to the procedure (2) in FIG.

In the following description, the amount of reducing material necessary for producing hot metal 1 t is referred to as a reducing material ratio (kg / tp). This reducing material is composed of coke, pulverized coal, or the like.
In this embodiment, in order to suppress the hot metal temperature drop during the resting wind and to recover the furnace heat early after the start of the resting wind, the amount of the reducing material put into the furnace before the resting wind is increased, and the reducing material ratio Is going to increase.

FIG. 3 shows the transition of the reducing material ratio from before the wind break to after the wind break.
Before the break, it operates at a higher reducing agent ratio than the normal reducing agent ratio.
As shown in FIG. 3, the difference between the maximum value of the reducing material ratio before the wind break and the value of the reducing material ratio during normal operation is referred to as the reducing material ratio increase (kg / tp) before the wind break. And The ratio of reducing material during normal operation was the average ratio of reducing material from 48 hours before the resting wind to 36 hours before the resting wind.

Collected more than 10 points of the reduction material ratio increase before the break and the slope of the hot metal temperature drop in the furnace, the horizontal axis is the reduction material ratio increase before the break, and the vertical axis is the inside of the furnace Based on the slope of the hot metal temperature drop, the past results collected were plotted to obtain the relationship. The obtained relationship is shown in FIG.
As shown in FIG. 4, it can be seen that the slope (° C./h) of the hot metal temperature decrease becomes smaller as the amount of increase in the reducing material ratio (kg / tp) before the wind break increases.

In FIG. 4, the approximate straight line obtained by the least square method is indicated by a dotted line. Further, in FIG. 4, a straight line passing through a point farthest from the approximate line in a plot in which the slope of the hot metal temperature decrease is larger than that of the approximate line is indicated by a solid line.
The solid line in FIG. 4 is a relational expression between the amount of increase in the reducing material ratio before the break and the slope of the hot metal temperature drop in the furnace. The relational expression is shown in Expression (1).

Slope of hot metal temperature decrease (℃ / h) = -0.0347 x Reducing material ratio increase before rest (kg / tp) + 8.1965 (1)
(A3)
The hot metal discharge status at the start of rest wind is stratified into hot metal discharge good data and defective hot metal discharge data. The lower limit temperature of the hot metal at which the hot metal discharge is good is determined in advance. This advance preparation procedure corresponds to the procedure (3) in FIG.

If the ratio of reducing material to be increased before the resting wind is insufficient, the hot metal temperature at the start of the resting wind is greatly lowered, and the fluidity of the hot metal in which hot metal and slag are mixed is lowered.
As described above, when the hot metal / slag fluidity is lowered, the viscosity is high and the hot metal does not flow or solidifies, which makes it difficult to discharge the hot metal from the furnace. There is a risk that it will lead to major troubles such as inability to drown.

Here, we examined the past performance data of 10 or more wind breaks.
Of the past performance data, the hot metal discharge status at the start of the off-air is good, the hot metal discharge good data, the poor hot metal discharge data, the hot metal discharge defective data, Stratified.
When categorizing the hot metal discharge status after the start of resting wind into good discharge data and defective discharge data, the following two points were used as a reference.

・ An example where the increase in hot metal remaining in the furnace caused problems in the air permeability in the furnace, resulting in poor ventilation and reduced wind.
・ Examples where the hot metal discharged outside the furnace has solidified and cannot be discharged.
In FIG. 5, the schematic of the flow of the hot metal which came out from the spout opening 2 is shown. As shown in FIG. 5, for example, when the slag discharged from the tap outlet 2 solidifies before flowing into the slag treatment equipment (dry pit 3, granulation equipment 4), or the slag has a high viscosity. If it does not flow, the output cannot be continued, that is, it cannot be output.

The above two points are the hot metal discharge failure data (impossible) at the start of resting wind, and the data that did not cause problems like the above two points are the hot metal discharge good data (good) ).
For data categorized by hot metal discharge status (good discharge data and defective discharge data), the horizontal axis is the break time and the vertical axis is the hot metal temperature at the start of the break, The past results were plotted to find the relationship. The obtained relationship is shown in FIG.

As shown in FIG. 6, when the hot metal temperature at the start of the resting wind falls below 1360 ° C., the hot metal discharge is poor, so the lower limit temperature of the hot metal temperature at the start of the resting wind is determined to be 1360 ° C.
(A4)
The relationship between the amount of increase in the reducing material ratio before the resting wind and the maximum value of [Si]% in the hot metal after the start of the resting wind is obtained in advance. This advance preparation procedure corresponds to the procedure (4) in FIG.

FIG. 7 shows the transition of [Si]% in the hot metal from before the wind break to after the wind break rise. In addition, [Si]% in the hot metal is a concentration indicated by mass% of [Si] contained in the hot metal. In addition, (concentration expressed in mass%) may be simply expressed as (%).
As shown in FIG. 7, it can be seen that the hot metal [Si]% reaches the maximum value when the wind is stopped, decreases thereafter, and returns to the hot metal [Si]% during normal operation.

  Therefore, the inventor of the present application sets the point that becomes a peak at the start of rest time as the maximum value of [Si]% in the hot metal. By the way, there is a point (small peak) in which [Si]% in the hot metal is slightly higher before the break, and the small peak is set as the maximum value of [Si]% in the hot metal (for example, Japanese Patent Laid-Open No. 2013-2013). However, as shown in FIG. 7, it is clear that [Si]% in the hot metal is maximized at the start of rest time, so it is not preferable to set the above-mentioned small peak as the maximum value.

Then, for past performance data of 10 or more pauses, collect the past performance data of the reduced material ratio increase before the wind break and the maximum value of [Si]% in hot metal, and the horizontal axis shows the ratio of the reduced material before the wind break. The amount of increase was used, the vertical axis was the maximum value of hot metal [Si]%, and the past performance data collected was plotted to obtain the relationship. The obtained relationship is shown in FIG.
The solid line in FIG. 8 is an approximate straight line obtained by the least square method. The straight line in FIG. 8 is a relational expression between the reduction material ratio increase before the wind break and the maximum value of [Si]% in the hot metal after the wind break-up. The relational expression is shown in Expression (2).

Maximum value of [Si]% in hot metal = 0.0104 x reducing material ratio increase before rest (kg / tp) + 0.5695 (2)
(A5)
In the start-up of the resting wind, appropriate conditions of basicity (CaO)% / (SiO ₂ )% of slag and (Al ₂ O ₃ )% in slag in which the hot metal discharge state is good are obtained in advance. This advance preparation procedure corresponds to the procedure (5) in FIG.

The basicity of slag is calculated by the following formula using (CaO)% and (SiO ₂ )% in slag. Note that (CaO)% is a concentration expressed by mass% of (CaO), and (SiO ₂ )% is a concentration expressed by mass% of (SiO ₂ ).
Slag basicity = (C / S) = (CaO)% ÷ (SiO ₂ )%
The slag component that satisfies the following two conditions is set to an appropriate value so that the hot metal discharge is good.

-The temperature of the discharged slag must not be lower than the crystallization temperature.
-The slag viscosity should be as low as possible.
In the present embodiment, the basicity of slag and the appropriate value of (Al ₂ O ₃ )% in the slag were set based on the following known documents.
According to the reference (Hoshi et al .: CAMP-ISIJ, 12 (1999), 709, 10), the crystallization temperature is defined as the temperature at which the slag decreases and the solid phase precipitates, and the viscosity of the slag rapidly increases. The following relational expressions are obtained for the slag components and the crystallization temperature.

Crystallization temperature (℃) = 195 × (C / S) + 7.1 × (MgO)% + 11.5 × (Al ₂ O ₃ )% + 0.9 × (TiO ₂ )% + 870.1
Usually, in the slag _{(MgO)%, (Al 2} O 3)%, (TiO 2)% is, (MgO)%: 5~8 ( %), (Al 2 O 3)%: 13.5~16 (% ), (TiO ₂ )%: 1 to 2 (%). Incidentally, (MgO)% is the concentration shown in weight percent _{(MgO), (Al 2 O} 3)% is the concentration shown in weight percent _{(Al 2 O 3), (} TiO 2)% is This is the concentration expressed as mass% of (TiO ₂ ).

In this embodiment, (MgO)% = 6.8%, (Al ₂ O ₃ )% = 14.0%, (TiO ₂ )% = 1.6%, and the relationship between basicity and crystallization temperature was determined according to the above formula. . The obtained relationship is shown in FIG.
Further, according to the reference (Hoshi et al .: CAMP-ISIJ, 12 (1999), 709, 10), the following relational expression is obtained for the viscosity of slag at 1400 ° C.
Viscosity = 0.3 × {12.6 × (C / S) ² −33.1 × (C / S) −0.52 × (MgO)% + 0.42 × (Al ₂ O ₃ )% − 0.29 × (TiO ₂ )% + 21.72 }
Further, the relationship between basicity and viscosity was determined according to the above formula, assuming that (MgO)% = 6.8%, (Al ₂ O ₃ )% = 14.0%, and (TiO ₂ )% = 1.6%. The obtained relationship is shown in FIG.

Applicable ranges of the above two formulas (crystallization temperature, viscosity) are as follows.
1.0 <(CaO)% / (SiO ₂ )% <1.4
4.5% <(MgO)% <8.5%
14% <(Al ₂ O ₃ )% <18%
In FIG. 11, the schematic of the flow of the hot metal discharged | emitted from the spout 2 is shown.

As shown in FIG. 11, the slag discharged from the furnace flows out of the furnace and is cooled with water in the granulating equipment 4 or gradually cooled in the dry pit 3 to become a recycled product. However, the discharged slag dissipates heat to the atmosphere and the output before reaching each cooling facility, and the temperature decreases.
Here, when each hot metal temperature was measured, the hot metal temperature measured by the main skin skinmer part 5 for separating the hot metal and the slag, and the slag temperature at the inlet of the dry pit 3 which is a slag slow cooling facility, It was confirmed that there was a difference of 40 ° C.

Then, by subtracting 40 ° C. of the slag temperature drop from the lower limit temperature 1360 ° C. of the hot metal set in (A3), the assumed minimum slag temperature is 1320 ° C.
As shown in FIG. 12, from the relationship between the slag basicity and the crystallization temperature, when the slag basicity is 1.22 or more and the slag temperature is 1320 ° C., the crystallization temperature falls below the crystallization temperature. In addition, the viscosity of the slag will increase.

Therefore, the basicity of slag must be set to less than 1.22.
Moreover, as shown in FIG. 13, from the relationship between the basicity of slag and the viscosity, when the basicity of slag is in the range of 1.0 to 1.3, the higher the basicity of slag, the lower the viscosity of slag. Therefore, it can be said that it is desirable that the slag has a higher basicity from the viewpoint of the viscosity of the slag.
FIG. 14 shows the relationship between the amount of reduction material ratio increase in the rest wind and the maximum value of [Si]% in the hot metal.

Referring to FIG. 14, it can be seen that the maximum value of [Si]% in the hot metal increases as the reducing material ratio increases, but there is variation.
In FIG. 14, the equation of the approximate straight line obtained by the least square method is shown by a solid line. Using this approximate straight line equation, the difference between the estimated value of estimated [Si]% in hot metal and [Si]% in hot metal of the past results is calculated. Shown with dotted lines. As can be seen from the two dotted lines in FIG. 14, there is a difference of about ± 0.27 at the maximum.

When [Si]% changes in hot metal, the basicity (C / S) in slag changes. The calculation method of basicity (C / S) in the slag is shown below.
Table 1 shows the charging amount (t / ch) for each raw material. Table 2 shows each component (%) for each raw material.

From the charge (t / ch) of all the raw materials shown in Table 1 and the components (mass% concentration) of each raw material charged into the blast furnace 1 such as ore, coke, pulverized coal and auxiliary raw materials shown in Table 2. The amount of charge (t / ch) of each component of .Fe (iron), SiO ₂ , MnO, TiO ₂ , CaO, Al ₂ O ₃ , and MgO is obtained by the following equation.
Charge of each component for each raw material (t / ch) = Each component in each raw material (%) x Charge of each raw material (t / ch)
Table 3 shows the charging amount (t / ch) of each component for each raw material.

Here, (t / ch) is the charging amount (t) per charge. In addition, raw fuel (charges) such as ore and coke necessary for one day is divided into about 80 to 100 (times / day).
Table 4 shows the total amount of each component charged for each raw material (total of Table 3).

Of the components shown in Table 4, CaO, Al ₂ O ₃ and MgO all become slag. On the other hand, a part of each component of SiO ₂ , MnO, and TiO ₂ becomes hot metal, and the rest of each component becomes slag.
Assuming that all of the Fe in the charge becomes molten iron, the Fe (t / ch) in molten iron is obtained by the following formula.
Fe (t / ch) in hot metal = T.Fe (t / ch) in charge
Further, the amount of Mn in hot metal and the amount of Ti in hot metal are simply calculated as follows.

Mn (t / ch) in hot metal = charging MnO (t / ch) x Mn distribution rate (%) x 55 ÷ 71
Ti (t / ch) in molten iron = charged TiO ₂ (t / ch) x Ti distribution rate (%) x 48 ÷ (48 + 16 x 2)
However, the Mn distribution rate (ratio of entering the hot metal) was 85%, and the Ti distribution rate was 50%.
Table 5 shows the hot metal component (t / ch) of only the known part, and Table 6 shows the hot metal component (%) of only the known part.

By the way, although a lot of carbon dissolves in the hot metal, the amount does not change greatly. Therefore, as shown in Table 6, [C]% in the hot metal was set to a fixed value of 4.8%. Table 6 shows an example in which [Si]% in the hot metal is given a value as appropriate, and [Si]% in the hot metal is 0.4%.
Solving from the known components shown in Tables 5 and 6 using the following three equations, Tables 7 and 8 are obtained.
That is, when the value of [Si]% in hot metal is given, [Si] (t / ch) in hot metal can be obtained by solving using the following three equations.

Total hot metal components (t / ch) = C (t / ch) + Fe (t / ch) + Si (t / ch) + Mn (t / ch) + Ti (t / ch)
That is, z = x + 89.25 + y + 0.16 + 0.17
Si (t / ch) = Hot metal component total (t / ch) x [Si]%
That is, y = z x 0.4 (%)
C (t / ch) = Hot metal component total (t / ch) x [C]%
That is, x = z x 4.8 (%)

  Then, the amount (t / ch) distributed to the slag is obtained by subtracting the amount distributed to the hot metal of each component shown in Table 5 from the total charged amount of each component shown in Table 4. Table 9 shows the amount (t / ch) distributed to the slag.

The amount of charged CaO, amount of charged Al ₂ O _3, amount of charged MgO, amount of SiO ₂ in slag, amount of MnO in slag, amount of TiO ₂ in slag were totaled to obtain the calculated amount of slag. Table 10 shows the calculated slag amount.

The amount of charged CaO, amount of charged Al ₂ O _{3 and the} amount of SiO ₂ in the slag were divided by the calculated amount of slag to calculate (SiO ₂ )%, (CaO)%, (Al ₂ O ₃ )% in the slag. . Table 11 shows each component (%) in the slag.

The basicity of slag is calculated by the following formula using (CaO)%, (SiO ₂ )% in slag.
Slag basicity = (C / S) = (CaO)% ÷ (SiO ₂ )%
Table 12 shows the slag basicity.

As described above, based on [Si]% = 0.4% in the hot metal exemplified, it is estimated that the basicity of slag is 1.27 and (Al ₂ O ₃ )% is 15.1 (%).
FIG. 15 shows changes in the estimated value of slag basicity (CaO)% / (SiO ₂ )% when [Si]% in hot metal changes in accordance with the basicity calculation method described above.
As shown in FIG. 15, for example, when [Si]% in hot metal changes by 0.27, it is estimated that the basicity of slag changes by about 0.11.

As shown in FIG. 16, even if the basicity of slag changes by 0.11 due to the fluctuation of [Si]% in hot metal, the target value of basicity of slag is maintained so that the basicity of slag set above is less than 1.22. Was set to 1.1.
Further, from the phase diagram of slag composed of CaO, SiO ₂ and Al ₂ O ₃ , the target value of (Al ₂ O ₃ )% was set to 13% so that the freezing point was lowest.

Subsequently, after preparing in advance along (A1) to (A5), the reducing material ratio increase amount and the auxiliary material to be introduced into the blast furnace 1 before the wind break are determined along (B1) to (B5).
(B1)
From the relationship between the amount of reduction material ratio increase before resting and the slope of the hot metal temperature decrease obtained in (A2), the preset resting time, and the hot metal temperature before resting, The amount of increase in the reducing material ratio before resting is determined so that the hot metal temperature is not lower than the lower limit temperature of hot metal previously obtained in (A3). This determination procedure corresponds to the procedure (6) in FIG.

During normal operation, the temperature of hot air is adjusted so that the hot metal temperature is 1510 ° C, but before hot air is adjusted, the hot metal temperature is adjusted to 1520 ° C. Here, the hot metal temperature before the break is 1520 ° C. In addition, the resting time is determined by the construction process to be performed during the resting period.
The slope of the hot metal temperature drop is determined so that the hot metal temperature does not fall below the lower limit temperature between the hot metal temperature 1520 ° C before the break and the start of the break.

Next, from the relationship between the amount of increase in the reducing material ratio before the wind break and the slope of the hot metal temperature decrease, the amount of increase in the reducing material ratio before the wind break required to prevent the hot metal temperature from falling below the lower limit temperature is determined.
For example, if the temperature decreases from 1520 ° C. to 1360 ° C. (lower limit temperature) after 30 hours of off-air, the slope of the hot metal temperature decrease is 5.3 (° C./h) as shown in FIG. It can be seen that the specific increase amount is 83 (kg / tp).

In this way, the reducing material ratio increase amount before the wind break is set so that the hot metal temperature for the wind break rise does not fall below the lower limit temperature.
(B2)
The maximum value of [Si]% in the hot metal after the start of the rest wind is estimated from the amount of reduction material ratio increase before the rest of the hot air determined so that the hot metal temperature at the start of the rest wind does not fall below the lower limit temperature of the hot metal. This estimation procedure corresponds to the procedure (7) in FIG.

As shown in FIG. 18, the hot metal after the start of the rest wind is calculated from the relationship between the reduction material ratio increase before the rest wind obtained in (A4) and the maximum value of [Si]% in the hot metal after the start of the rest wind. Estimate the maximum value of medium [Si]%.
(B3)
From the estimated maximum value of [Si] (%) in the hot metal, the slag basicity (C / S) and the estimated value of (Al ₂ O ₃ )% are obtained. This estimation procedure corresponds to procedure (8) in FIG.

Similar to the calculation method of basicity in slag described in (A5), from the value of [Si]% in hot metal, the basicity of slag and (Al ₂ O ₃ )% are calculated and estimated values are calculated. Ask.
(B4)
Slag basicity (CaO)% / (SiO ₂ )% and (Al ₂ O ₃ )% at the maximum value of [Si]% in hot metal after the start of resting wind Determine raw materials. This determination procedure corresponds to the procedure (9) in FIG.

The basic amount of slag and (Al ₂ O ₃ )% are calculated in the same manner as in the method for calculating the basicity in slag described in (A5) by changing the amount of auxiliary material used. By repeating this calculation, the basicity of the slag and the amount of the auxiliary material to be introduced into the blast furnace 1 at which (Al ₂ O ₃ )% becomes the target values are determined.
In this way, after the determined reducing material ratio increase amount and the auxiliary material are put into the blast furnace 1 before the resting wind, the resting wind is performed, and then the resting wind start-up is performed to restart the operation of the blast furnace 1.
[Example]
Below, the Example of the blast furnace resting method of this invention is described based on figures.

First, implementation conditions are shown below.
For the blast furnace 1, a bell armor blast furnace with an internal volume of 4500 m ³ and a number of tap holes was used. Regarding the operating conditions during normal operation, the amount of molten iron was 8000 to 8500 (t / D), and the hot metal temperature was 1480 ° C to 1540 ° C. The reducing material ratio was 500 to 530 (kg / tp). Coke and pulverized coal were used as the reducing material. As the raw material, sintered ore, pellets and lump ore were used. Regarding the resting conditions, the resting time was 24 to 40 hours.

(A1)
FIG. 19 shows the transition of the hot metal temperature from before the wind break to after the wind break rise.
The hot metal temperature was measured at the main skin skinmer part 5 where the hot metal discharged from the spout 2 was separated into hot metal and slag. After the start of brewing, measurement was started from the timing when about 300 tons of hot metal was discharged, and measurement was performed every 30 minutes to 1 hour.

As a result, as shown in FIG. 19, the hot metal temperature measured at the end before the wind break was 1524 ° C, and the hot metal temperature measured after the start of the wind break was 1367 ° C. The molten iron temperature obtained is 1524-1367 = 157 ° C.
In addition, since the rest time is 30.2 hours, the slope of the hot metal temperature drop from before the rest to the start of the rest wind is obtained as 157 ÷ 30.2 = −5.2 (° C./h).

By the way, for problems caused by not implementing (A1), if the slope of the hot metal temperature drop in the furnace between the start of the rest and the start of the rest is not calculated, the reducing material ratio increase before the rest of (A2) The relationship between the amount and the slope of the hot metal temperature drop in the furnace between the start of the rest and the start of the rest cannot be obtained.
(A2)
Collected 10 or more points of past reductions in hot metal temperature increase before the break and the slope of the hot metal temperature drop in the furnace. Then, the past results were plotted to find the relationship. The obtained relationship is shown in FIG.

In FIG. 20, an approximate straight line obtained by the least square method is shown by a dotted line. Further, in FIG. 20, a straight line that passes through a point that is farthest from the approximate straight line in a plot in which the gradient of the hot metal temperature drop in the furnace is larger than the approximate straight line is indicated by a solid line.
The solid line in FIG. 20 is a relational expression between the amount of increase in the reducing material ratio before resting and the slope of the hot metal temperature decrease in the furnace. The relational expression is shown in Expression (1).

Slope of hot metal temperature decrease (℃ / h) = -0.0347 x Reducing material ratio increase before rest (kg / tp) + 8.1965 (1)
By the way, for the troubles caused by not implementing (A2), the relationship between the reduction material ratio increase before the break and the slope of the hot metal temperature drop in the furnace between the break and start of the break must be obtained. In addition, it is not possible to determine the amount of reduction material ratio increase before resting in the blast furnace 1.

(A3)
About past performance data of 10 times or more of wind breaks, data was divided into good data and bad data of hot metal discharge status at the start of the wind break. In addition, about the classification of the hot metal discharge situation at the time of a rest wind start-up, it performed based on the following two points.
・ An example where the increase in hot metal remaining in the furnace caused problems in the air permeability in the furnace, resulting in poor ventilation and reduced wind.

・ Examples where the hot metal discharged outside the furnace has solidified and cannot be discharged.
In FIG. 21, the schematic of the flow of the hot metal which came out from the spout opening 2 is shown. As shown in FIG. 21, for example, when the slag discharged from the tap outlet 2 solidifies before flowing into the slag treatment facility (dry pit 3, granulation facility 4), or the slag has a high viscosity. If it does not flow, the output cannot be continued, that is, it cannot be output.

The above two points are the hot metal discharge failure data (impossible) at the start of resting wind, and the data that did not cause problems like the above two points are the hot metal discharge good data (good) ).
For the hot metal discharge status stratified data (good discharge data and defective discharge data), plot the past results with the horizontal axis as the rest time and the vertical axis as the hot air temperature at the start of the rest. Sought a relationship. The obtained relationship is shown in FIG.

From FIG. 22, when the hot metal temperature at the start of the rest wind falls below 1360 ° C., the hot metal discharge is poor, so the lower limit temperature of the hot metal temperature at the start of the rest wind is determined to be 1360 ° C.
By the way, about the trouble that occurs by not carrying out (A3), if the lower limit temperature of the hot metal at the start of the rest wind is not known, the reduction before the rest of the wind put into the blast furnace 1 will be caused. The amount of material ratio increase cannot be determined.

(A4)
FIG. 23 shows the transition of [Si]% in the hot metal from before the wind break to after the wind break rise. [Si]% in the hot metal is a mass% concentration of [Si] contained in the hot metal.
Sampling was performed once every 250 to 280 t and analyzed by X-ray diffraction. As shown in FIG. 23, [Si]% during hot metal reaches its maximum value when the wind is stopped, decreases thereafter, and returns to [Si]% during hot metal operation during normal operation.

For past performance data of 10 or more wind breaks, collect the reduction material ratio increase before the wind break and the past performance data of the maximum value of [Si]% in hot metal, and the horizontal axis shows the reduction material ratio increase before the wind break The amount was plotted, and the vertical axis was the maximum value of [Si]% in the hot metal, and these data were plotted to obtain the relationship. The relationship is shown in FIG.
The solid line in FIG. 24 is an approximate straight line obtained by the least square method. This approximate straight line was used as a relational expression between the amount of increase in the reducing material ratio before the break and the maximum value of [Si]% in the hot metal after the break. The relational expression is shown in Expression (2).

Maximum value of [Si]% in hot metal = 0.0104 x reducing material ratio increase before rest (kg / tp) + 0.5695 (2)
By the way, for the trouble that occurs due to not implementing (A4), if the relationship between the reduced material ratio increase before the break and the maximum value of [Si]% in the hot metal after the break is started, the base of the slag The estimated value of (Al ₂ O ₃ )% cannot be obtained.
(A5)
By the way, in obtaining the crystallization temperature, the following equation is used.

Crystallization temperature (℃) = 195 × (C / S) + 7.1 × (MgO)% + 11.5 × (Al ₂ O ₃ )% + 0.9 × (TiO ₂ )% + 870.1
However, (MgO)% = 6.8%, (Al ₂ O ₃ )% = 14.0%, and (TiO ₂ )% = 1.6%.
According to the above formula, the relationship between basicity and crystallization temperature is determined. The relationship is shown in FIG.
Moreover, when calculating | requiring a viscosity, suppose that the following formula is used.
Viscosity = {1 + 0.007 × (1500−T)} × {12.6 × (C / S) ² −33.1 × (C / S) −0.52 × (MgO)% + 0.42 × (Al ₂ O ₃ )% − 0.29 × (TiO ₂ )% + 21.72}
However, (MgO)% = 6.8%, (Al ₂ O ₃ )% = 14.0%, and (TiO ₂ )% = 1.6%.

The relationship between basicity and viscosity is determined according to the above formula. The relationship is shown in FIG.
Here, when each hot metal temperature was measured, the hot metal temperature measured by the main skin skinmer part 5 for separating the hot metal and the slag and the temperature of the slag at the inlet of the dry pit 3 which is a slag slow cooling facility were 30 ° C. to 40 ° C. It was confirmed that there was a difference in ° C.
Then, when the slag temperature drop of 40 ° C. is subtracted from the hot metal lower limit temperature of 1360 ° C. set in (A3), the estimated minimum slag temperature is 1320 ° C.

As shown in FIG. 27, based on the relationship between the basicity of slag and the crystallization temperature, when the basicity of slag is 1.22 or more and the slag temperature is 1320 ° C., the crystallization temperature falls below the crystallization temperature. In addition, the viscosity of the slag will increase.
Therefore, the basicity of slag must be set to less than 1.22.
Moreover, as shown in FIG. 28, from the relationship between the basicity and viscosity of slag, when the basicity of slag is in the range of 1.0 to 1.3, the higher the basicity of slag, the lower the viscosity of slag. Therefore, it can be said that it is desirable that the slag has a higher basicity from the viewpoint of the viscosity of the slag.

FIG. 29 shows the relationship between the amount of reduction material ratio increase during resting wind and the maximum value of [Si]% in hot metal.
Referring to FIG. 29, it can be seen that the maximum value of [Si]% in the hot metal increases as the reducing material ratio increases, but there is variation.
In FIG. 29, the equation of the approximate straight line obtained by the least square method is shown by a solid line. Using this approximate straight line equation, the difference between the estimated value of estimated [Si]% in hot metal and [Si]% in hot metal of the past results is calculated. Shown with dotted lines. As can be seen from the two dotted lines in FIG. 29, there is a difference of about ± 0.27 at the maximum.

When [Si]% changes in hot metal, the basicity (C / S) in slag changes. The calculation method of basicity (C / S) in the slag is shown below.
From the raw material charge (t / ch) and the components (mass% concentration) of each raw material to be fed into the blast furnace 1 such as ore, coke, pulverized coal and auxiliary raw materials, T.Fe (iron content), SiO ₂ , MnO, TiO ₂ , CaO, Al ₂ O ₃ and MgO are charged (t / ch) (see Tables 1 to 3).

Here, (t / ch) is the charging amount (t) per one time. In addition, raw fuel (charges) such as ore and coke necessary for one day is divided into about 80 to 100 (times / day).
Of the above components (see Table 4), CaO, Al ₂ O ₃ and MgO all become slag. On the other hand, a part of each component of SiO ₂ , MnO, and TiO ₂ becomes hot metal, and the rest of each component becomes slag.

Assuming that all of the Fe in the charge becomes molten iron, the Fe (t / ch) in molten iron is obtained by the following formula.
Fe (t / ch) in hot metal = T.Fe (t / ch) in charge
Further, the amount of Mn in hot metal and the amount of Ti in hot metal are simply calculated as follows.
Mn (t / ch) in hot metal = charging MnO (t / ch) x Mn distribution rate (%) x 55 ÷ 71
Hot metal Ti (t / ch) = charged TiO ₂ (t / ch) x Ti distribution rate (%) x 48 ÷ 80
However, the Mn distribution rate was 85% and the Ti distribution rate was 50%.

By the way, although a lot of carbon dissolves in the hot metal, the amount does not change greatly. Therefore, [C]% in the hot metal was set to a fixed value of 4.8%.
Moreover, when the value of [Si]% in the hot metal is given and the equation is solved by the following three equations, Si (t / ch) in the hot metal can be obtained (see Tables 5 to 8).
Total hot metal components (t / ch) = C (t / ch) + Fe (t / ch) + Si (t / ch) + Mn (t / ch) + Ti (t / ch)
Si (t / ch) = Hot metal component total (t / ch) x [Si]%
C (t / ch) = Hot metal component total (t / ch) x [C]%
The amount distributed to the slag (see Table 9) is obtained by subtracting the amount distributed to the hot metal of each component (see Table 5) from the total charged amount of each component (see Table 4).

The amount of charged CaO, amount of charged Al ₂ O _3, amount of charged MgO, amount of SiO ₂ in slag, amount of MnO in slag, amount of TiO ₂ in slag were totaled to obtain the calculated amount of slag (see Table 10).
The amount of charged CaO, amount of charged Al ₂ O _{3 and the} amount of SiO ₂ in the slag were divided by the calculated amount of slag to calculate (SiO ₂ )%, (CaO)%, (Al ₂ O ₃ )% in the slag. (See Table 11).
The basicity of slag is calculated by the following formula using (CaO)%, (SiO ₂ )% in the slag (see Table 12).

Slag basicity = (C / S) = (CaO)% ÷ (SiO ₂ )%
FIG. 30 shows changes in the estimated value of slag basicity (CaO)% / (SiO ₂ )% when [Si]% in hot metal changes according to the above-described calculation method of basicity in slag. .
As shown in FIG. 30, when [Si]% in hot metal changes by 0.27, it is estimated that the basicity of slag changes by about 0.11.

As shown in FIG. 31, even if the slag basicity fluctuates by 0.11 due to the variation of [Si]% in the hot metal, the target value of the slag basicity is set so that the basicity of the slag set above is kept below 1.22. Set to 1.1.
Further, from the phase diagram of slag composed of CaO, SiO ₂ and Al ₂ O ₃ , the target value of (Al ₂ O ₃ )% was set to 13% so that the freezing point was lowest.

As described above, (A1) to (A5) are the preliminary preparation steps for determining the reducing material ratio increase amount and auxiliary materials before the break.
By the way, with regard to the troubles caused by not implementing (A5), if the basic condition of slag that makes good hot metal discharge at the start of rest time, and the proper condition of (Al ₂ O ₃ )% are not required, The amount added cannot be determined.
(B1)
First, the slope of the hot metal temperature drop is obtained. When calculating with equation (1) and the rest time: 36 hours, hot metal temperature before rest: 1520 ° C, lower limit temperature of hot metal: 1360 ° C,
Slope of hot metal temperature drop (° C / h) =-(minimum temperature (° C)-hot metal temperature (° C) before resting air) / resting time (h)
=-(1360-1520) /36=4.44
By substituting the slope of the hot metal temperature decrease = 4.44 obtained in this way into the equation (1), the reduction material ratio increase before the break can be obtained.

Reducing material ratio increase before rest (kg / tp) = (8.1965−4.44) /0.0347=108
From this result, the amount of increase in the reducing agent ratio before the wind break was set to 110 (kg / tp).
By the way, regarding the trouble caused by not performing (B1), [Si]% in the hot metal after the start of the rest wind cannot be estimated unless the reducing material ratio increase amount before the rest is determined.
(B2)
Next, the reduction material ratio increase before the wind break = 110 (kg / tp) obtained in (B1) above is substituted into the formula (2), and [Si]% in the hot metal after the wind break is started. The maximum value of was estimated.

Maximum value of [Si]% in hot metal = 0.0104 x Reducing material ratio increase before rest (kg / tp) + 0.5695
= 0.0104 × 110 + 0.5695 = 1.7
The maximum value of [Si]% in hot metal after the start of resting wind is estimated to be 1.7 (%).
By the way, for the troubles caused by not implementing (B2), if the maximum value of [Si]% in hot metal after the start of resting is not estimated, the basicity of slag and (Al ₂ O ₃ )% are estimated. Can not do it.
(B3)
First, referring to Tables 13 to 24, the basicity of slag during normal operation and (Al ₂ O ₃
) A procedure for estimating% will be described. The data shown in Tables 13 to 24 is an example during normal operation.

From the raw material charge (t / ch) and the components (mass% concentration) of each raw material to be fed into the blast furnace 1 such as ore, coke, pulverized coal and auxiliary raw materials, T.Fe (iron content), SiO ₂ , MnO, TiO ₂ , CaO, Al ₂ O ₃ , MgO, the charging amount (t / ch) of each component is obtained from the following formula (see Tables 13 to 15).
Charge of each component for each raw material (t / ch) = Each component in each raw material (%) x Charge of each raw material (t / ch)

Of the following components (see Table 16), CaO, Al ₂ O ₃ and MgO all become slag. On the other hand, a part of each component of SiO ₂ , MnO, and TiO ₂ becomes hot metal, and the rest of each component becomes slag. All T.Fe will become hot metal.

The component in each hot metal is calculated from the following equation using the amount of the above-described component.
Fe (t / ch) in hot metal = T.Fe (t / ch) in charge
Mn (t / ch) in hot metal = charging MnO (t / ch) x Mn distribution rate (%) x 55 ÷ 71
Hot metal Ti (t / ch) = charging Ti (t / ch) x Ti distribution rate (%) x 48 ÷ (48 + 16 x 2)
However, the Mn distribution rate was 85% and the Ti distribution rate was 50%.

  As shown in Table 18, [C]% in the hot metal was 4.8 (%). Further, [Si]% in the hot metal is given a value as appropriate, and here, an example in which [Si]% in the hot metal is 0.4 (%) is shown.

As described above, when known components shown in Tables 17 and 18 are solved using the following equations, Tables 19 and 20 are obtained.
Total hot metal components (t / ch) = C (t / ch) + Fe (t / ch) + Si (t / ch) + Mn (t / ch) + Ti (t / ch)
That is, z = x + 96.38 + y + 0.18 + 0.18
Si (t / ch) = Hot metal component total (t / ch) x [Si]%
That is, y = z x 0.4 (%)
C (t / ch) = Hot metal component total (t / ch) x [C]%
That is, x = z x 4.8 (%)

  The amount distributed to the slag (see Table 21) is calculated by subtracting the amount distributed to the hot metal of each component (see Table 17) from the total charged amount of each component (see Table 16).

The amount of charged CaO, amount of charged Al ₂ O _3, amount of charged MgO, amount of SiO ₂ in slag, amount of MnO in slag, amount of TiO ₂ in slag were totaled to obtain the calculated amount of slag (see Table 22).

The amount of charged CaO, amount of charged Al ₂ O _{3 and the} amount of SiO ₂ in the slag were divided by the calculated amount of slag to calculate (SiO ₂ )%, (CaO)%, (Al ₂ O ₃ )% in the slag. (See Table 23).

The basicity of the slag is calculated using (CaO)%, (SiO ₂ )% in the slag (see Table 24).

During normal operation, the basicity of slag is estimated to be 1.27, and (Al ₂ O ₃ )% is estimated to be 15.3%, based on [Si]% = 0.4% in the illustrated hot metal.
Subsequently, a comparative example of the procedure for estimating the basicity of slag and (Al ₂ O ₃ )% in the estimated maximum value of [Si]% in molten iron will be described with reference to Tables 25 to 36. The data shown in Tables 25-36 is an example given for comparison with the blast furnace quiescent method of the present invention.

From the raw material charge (t / ch) and the components (mass% concentration) of each raw material to be fed into the blast furnace 1 such as ore, coke, pulverized coal and auxiliary raw materials, T.Fe (iron content), SiO ₂ , MnO, TiO ₂ , CaO, Al ₂ O ₃ , MgO, the charging amount (t / ch) is obtained from the following formula (see Tables 25 to 27).
Charge of each component for each raw material (t / ch) = Each component in each raw material (%) x Charge of each raw material (t / ch)

Of the following components (see Table 28), CaO, Al ₂ O ₃ and MgO all become slag. On the other hand, a part of each component of SiO ₂ , MnO, and TiO ₂ becomes hot metal, and the rest of each component becomes slag. All T.Fe will become hot metal.

The component in each hot metal is calculated from the following equation using the amount of the above-described component.
Fe (t / ch) in hot metal = T.Fe (t / ch) in charge
Mn (t / ch) in hot metal = charging MnO (t / ch) x Mn distribution rate (%) x 55 ÷ 71
Hot metal Ti (t / ch) = charging Ti (t / ch) x Ti distribution rate (%) x 48 ÷ (48 + 16 x 2)
However, the Mn distribution rate (%) was 85%, and the Ti distribution rate (%) was 50%.

  As shown in Table 30, the [C]% in the hot metal was 4.8%. Also, [Si]% in the hot metal is given a value as appropriate, and here, an example in which [Si]% in the hot metal is 1.7% is shown.

As described above, when the known components shown in Tables 29 and 30 are solved using the following equations, Tables 31 and 32 are obtained.
Total hot metal components (t / ch) = C (t / ch) + Fe (t / ch) + Si (t / ch) + Mn (t / ch) + Ti (t / ch)
That is, z = x + 78.21 + y + 0.14 + 0.16
Si (t / ch) = Hot metal component total (t / ch) x [Si]%
That is, y = z x 1.7 (%)
C (t / ch) = Hot metal component total (t / ch) x [C]%
That is, x = z x 4.8 (%)

  The amount distributed to the slag (see Table 33) is calculated by subtracting the amount distributed to the hot metal of each component (see Table 29) from the total charged amount of each component (see Table 28).

The amount of charged CaO, amount of charged Al ₂ O _3, amount of charged MgO, amount of SiO ₂ in slag, amount of MnO in slag, amount of TiO ₂ in slag were totaled to obtain a calculated slag amount (see Table 34).

The amount of charged CaO, amount of charged Al ₂ O _{3 and the} amount of SiO ₂ in the slag were divided by the calculated amount of slag to calculate (SiO ₂ )%, (CaO)%, (Al ₂ O ₃ )% in the slag. (See Table 35).

The basicity of the slag is calculated using (CaO)%, (SiO ₂ )% in the slag (see Table 36).

As described above, based on the maximum value of [Si]% in the hot metal illustrated as 1.7%, it is estimated that the basicity of slag is 1.69 and (Al ₂ O ₃ )% is 17.7%.
In this way, the basicity of slag exceeds 1.22, and (Al ₂ O ₃ )% exceeds 13%, so the hot metal and slag fluidity will decrease, and hot metal will be discharged from the furnace. May become difficult (cannot be found).

By the way, with regard to the troubles caused by not implementing (B3), the basic condition of slag and the estimated value of (Al ₂ O ₃ )% are not obtained from the maximum value of [Si]% in the hot metal, satisfying the appropriate condition The addition amount of such auxiliary materials cannot be determined.
(B4)
Here, a procedure for estimating the basicity of slag and (Al ₂ O ₃ )% at the maximum value of [Si]% in the molten iron will be described with reference to Tables 37 to 50. The data shown in Tables 37 to 50 is an example showing this embodiment.

In this example, while changing the amount of auxiliary material used, calculate the slag component by the calculation method shown in (A5), the basicity of the slag is 1.1, (Al ₂ O ₃ )% is the target value The lime was increased from 3.0 (t / ch) to 7.9 (t / ch) and the meteorite was increased from 0 to 5.9 (t / ch) (see Table 37).
From the raw material charge (t / ch) and the components (mass% concentration) of each raw material to be fed into the blast furnace 1 such as ore, coke, pulverized coal and auxiliary raw materials, T.Fe (iron content), SiO ₂ , MnO, TiO ₂ , CaO, Al ₂ O ₃ , and MgO are charged in amounts (t / ch) from the following formulas (see Tables 37 to 39).

  Charge of each component for each raw material (t / ch) = Each component in each raw material (%) x Charge of each raw material (t / ch)

Of the following components (see Table 40), CaO, Al ₂ O ₃ and MgO all become slag. On the other hand, a part of each component of SiO ₂ , MnO, and TiO ₂ becomes hot metal, and the rest of each component becomes slag. All T.Fe will become hot metal.

The component in each hot metal is calculated from the following equation using the amount of component charge.
Fe (t / ch) in hot metal = T.Fe (t / ch) in charge
Mn (t / ch) in hot metal-= charging MnO (t / ch) x Mn distribution rate (%) x 55/71
Hot metal Ti (t / ch) = charging Ti (t / ch) x Ti distribution rate (%) x 48 ÷ (48 + 16 x 2)
However, the Mn distribution rate (%) was 85%, and the Ti distribution rate (%) was 50%.

  As shown in Table 42, [C]% in the hot metal was 4.8%. Further, [Si]% in the hot metal is given a value as appropriate, and here, an example in which [Si]% in the hot metal is 1.7% is shown.

Thus, when the known components shown in Table 41 and Table 42 are solved using the following equations, Table 43 and Table 44 are obtained.
Total hot metal components (t / ch) = C (t / ch) + Fe (t / ch) + Si (t / ch) + Mn (t / ch) + Ti (t / ch)
That is, z = x + 78.29 + y + 0.14 + 0.16
Si (t / ch) = Hot metal component total (t / ch) x [Si]%
That is, y = z x 1.7 (%)
C (t / ch) = Hot metal component total (t / ch) x [C]%
That is, x = z x 4.8 (%)

  The amount distributed to the slag (see Table 45) is calculated by subtracting the amount distributed to the hot metal of each component (see Table 41) from the total charged amount of each component (see Table 40).

The amount of charged CaO, amount of charged Al ₂ O _3, amount of charged MgO, amount of SiO ₂ in slag, amount of MnO in slag, amount of TiO ₂ in slag were totaled to obtain a calculated slag amount (see Table 46).

The amount of charged CaO, amount of charged Al ₂ O _{3 and the} amount of SiO ₂ in the slag were divided by the calculated amount of slag to calculate (SiO ₂ )%, (CaO)%, (Al ₂ O ₃ )% in the slag. (See Table 47).

The basicity of the slag is calculated using (CaO)%, (SiO ₂ )% in the slag (see Table 48).

From the exemplified maximum value of [Si]% in the hot metal = 1.7%, it is estimated that the basicity of slag is 1.1 and (Al ₂ O ₃ )% is 13.0%.
From the above results, the blast furnace 1 was able to start up without taking off the hot metal discharge from the furnace.
By the way, about the trouble that occurs by not carrying out (B4), the auxiliary material is added and the slag basicity that satisfies the proper condition is not set to (Al ₂ O ₃ )%, the slag fluidity will decrease. . Thus, when the fluidity of the slag is lowered, it becomes difficult to discharge the hot metal from the furnace, which may lead to a large trouble such as inability to discharge.

Tables 49 and 50 show the results of other examples of the blast furnace resting method according to the present invention.
As shown in Tables 49 and 50, with regard to the resting wind under other implementation conditions, the resting wind could be started up without deteriorating the hot metal discharge by implementing the method of the present invention.

According to the present invention described above, as shown in the procedure (2) in FIG. 32, the relationship between the reducing material ratio increase before the wind break and the slope of the hot metal temperature decrease is obtained, and the procedure (3) in FIG. As shown in FIG. 5, by determining the lower limit temperature of the hot metal, it is possible to determine the amount of reduction material ratio increase according to the rest time in the rest stage.
Further, as shown in the procedure (3) of FIG. 32, the target lower limit temperature of the hot metal can be determined by stratifying the hot metal discharge at the start of the rest wind as good and bad.

In addition, as shown in the procedure (4) of FIG. 32, by calculating the relationship between the amount of reduction material ratio increase before the wind break and the maximum value of [Si]% in the hot metal at the start of the wind break, In addition, the maximum value of [Si]% in the hot metal can be predicted, and the slag component can be adjusted in advance.
By implementing the present invention, it is possible to smoothly and smoothly start up the blast furnace 1 with respect to the resting (resting) and the resting (starting operation). It is possible to shift to normal operation without deteriorating the in-furnace air permeability caused by the defect and reducing the air flow accompanying it.

  In the embodiment disclosed this time, matters not explicitly disclosed, for example, operating conditions and operating conditions, various parameters, dimensions, weights, volumes, etc. of components deviate from the areas normally practiced by those skilled in the art. However, matters that can be easily assumed by those skilled in the art are employed.

1 Blast Furnace 2 Outlet 3 Dry Pit 4 Granulation Facility 5 Main Skinner

Claims (1)

From the hot metal temperature before resting time, the hot metal temperature after the start of the resting wind, and the resting time, the slope of the hot metal temperature decrease during the resting wind start from before the resting time is obtained in advance,
Obtaining in advance the relationship between the reduced material ratio increase amount before the resting wind and the slope of the hot metal temperature decrease during the resting wind start-up from the determined resting air,
The discharge condition of put that soluble Zukukasu the deactivation air launch, the discharge good data of the hot metal debris to stratify in the discharge failure data of the hot metal debris, from the discharge data of the molten iron slag which is stratified, Obtaining the lower limit temperature of the hot metal in which the hot metal discharge state at the start of the rest wind is favorable,
Preliminarily determining the relationship between the amount of reduction material ratio increase before the pause and the maximum value of [Si] (mass% concentration) in the hot metal after the start of the pause,
Basicity Luz lug Do discharge conditions favorable of the molten iron slag in said holiday wind raising (CaO (wt% concentration) / SiO ₂ (wt% concentration)), and slag (Al ₂ O ₃₎ (mass (Concentration) is determined in advance,
Moreover,
From the relationship between the reducing material ratio increase amount and the slope of the hot metal temperature decrease, the hot air time and the hot metal temperature before the hot air breakage, the hot metal temperature at the start of the hot air breakage is determined in advance. Determine the reducing material ratio increase amount so as not to fall below the lower limit temperature,
From the amount of reduction material ratio increase determined so that the hot metal temperature at the start of the rest wind does not fall below the lower limit temperature of the hot metal, [Si] (mass% concentration) in the hot metal after the start of the rest wind Estimate the maximum value,
From the estimated maximum value of [Si] (mass% concentration) in the hot metal, the basicity of the slag (CaO (mass% concentration) / SiO ₂ (mass% concentration)), and in the slag (Al ₂ O ₃ ) Obtain an estimate of (mass% concentration)
Basicity of the slag (CaO (mass% concentration) / SiO ₂ (mass% concentration)) at the maximum value of [Si] (mass% concentration) in the hot metal after the start of the rest wind, and in the slag In order to satisfy the above-mentioned proper condition (Al ₂ O ₃ ) (mass% concentration), the auxiliary material to be charged into the blast furnace is determined
After the determined reducing material ratio increase amount and the auxiliary material are put into the blast furnace before the resting air, the resting air is performed, and then the resting air is started up to restart the operation of the blast furnace. Characterized blast furnace air suspension method.