JP2022144966A - Blast furnace operation method - Google Patents

Abstract

[Problem] To increase the efficiency of the blast furnace and reduce the amount of _CO2 generated in the operation of the blast furnace in which a reducing gas containing hydrogen is injected into the blast furnace while using unburned coal-containing agglomerate ore as part of the raw material for the blast furnace. Provided is a method of operating a blast furnace that can be suppressed.
[Solution] When the amount of hydrogen in the bosh gas is X and the carbon content of the non-burned coal-containing agglomerate ore is Y, the operation is performed within the operation area surrounded by the following formulas (1) to (3). It is a blast furnace operating method characterized by doing.
(1): Y=−0.06X+29.07
(2): X=0
(3): Y=0
In the formula, the unit of X is Nm ³ /t-pig and the unit of Y is % by mass.
[Selection drawing] Fig. 5

Description

The present invention relates to a method of operating a blast furnace, and more particularly, in an operation in which unburned coal-containing agglomerate ore is used as part of the blast furnace raw material and a reducing gas containing hydrogen is blown into the blast furnace, the efficiency of the blast furnace is improved. The present invention relates to a blast furnace operating method capable of obtaining pig iron by increasing the amount of CO 2 and suppressing the amount of CO ₂ generated.

Under the social demand for _CO2 emission reduction, about 70% of the _CO2 emission in the steel industry comes from the blast furnace, so it is necessary to reduce the _CO2 emission from the blast furnace as much as possible.

In a blast furnace, coke is used as a main reducing agent in the ironmaking process of reducing iron oxide to metallic iron. Since the carbon contained in this coke is finally released into the atmosphere as CO ₂ , one of the measures for reducing CO ₂ emissions is the effective use of hydrogen as a reducing agent. The CO generated by coke combustion reduces iron oxide to generate _CO2 , whereas the product of reduction by hydrogen is _H2O , and part of the use of carbon-based reducing agents is replaced by hydrogen-based is effective in reducing CO ₂ emissions.

Blowing of hydrogen gas into such a blast furnace has been carried out for a relatively long time. For example, in Patent Document 1, in a method of operating a blast furnace in which a fluid reducing agent containing H ₂ is added during air blowing, a fluid containing H ₂ is fed from a blowpipe or a blow pipe that is open facing a tuyere. It describes a method of blowing in a reducing agent and adjusting the distribution of _H2 gas in the radial direction in the furnace by changing the discharge position and flow velocity during the blowing, thereby maintaining the inside of the furnace in an appropriate reducing state. ing.

Further, in Patent Document 2, the components and amounts of the in-furnace gas are measured at a plurality of predetermined locations in the radial direction of the blast furnace at each of a plurality of predetermined locations in the height direction of the massive band portion of the blast furnace shaft, and the measured values are Calculate the hydrogen gas utilization rate based on, obtain the difference in the hydrogen gas utilization rate between the positions in the height direction of the massive belt portion, and adjust the distribution of the top charge based on this difference. It describes a method for stabilizing blast furnace operation and improving the utilization rate of reducing gas by maintaining the difference in utilization rate within a predetermined range.

On the other hand, by using a non-fired coal-containing agglomerate ore obtained by agglomerating carbonaceous fine powder such as coke or coal and iron oxide fine powder using a hydraulic binder such as cement, reduction in blast furnace operation can be achieved. It is possible to reduce the material ratio. This non-calcined coal-bearing agglomerate ore is made by granulating a finely powdered iron-containing raw material together with a hydraulic binder such as cement and water to form an agglomerate such as a pellet, which is then cured to increase its strength. Carbonaceous agglomerate ore, which is produced by a non-fired agglomeration process that obtains agglomerate ore by increasing it, is impossible with a fired agglomeration process that obtains sintered ore and fired pellets. can be added inside. Therefore, it leads to a reduction in the amount of coke used.

Such non _- calcined coal-containing agglomerate ore is used as part of the blast furnace raw material. Regarding the gas reduction rate ηCO, which indicates the efficiency, a reference value is determined in advance, and this ηCO is measured during the operation of the blast furnace. A method for stabilizing the gas reduction efficiency of a blast furnace at a high level is disclosed by adjusting the reactivity (JIS reactivity).

JP-A-58-87210 JP-A-6-57315 JP 2015-74799 A

While there is a need to reduce _CO2 emissions from blast furnaces, the injection of hydrogen-containing reducing gas into the blast furnace and the use of unfired coal-containing agglomerate ore as part of the raw material for blast furnaces have already been implemented. ing. However, as in the above-mentioned patent document, when using a reducing gas or a non-burning coal-containing agglomerate ore, although appropriate conditions are sought for each, the blowing of the reducing gas and the non-burning inclusion No effort has been made so far to focus on the efficiency of the entire blast furnace when using coal agglomerates at the same time.

Under these circumstances, the present inventors have made intensive studies to solve the above problems, and as a result, when using unburned coal-bearing agglomerate ore when injecting reducing gas into the blast furnace, It was found that there is a relationship between the amount of carbon contained in the non-calcined coal-containing agglomerate ore and the amount of blown reducing gas in order to increase the efficiency. By operating the blast furnace based on such a relationship, the efficiency of the blast furnace can be increased to obtain pig iron, and the amount of CO ₂ generated can be suppressed. completed.

Accordingly, an object of the present invention is to increase the efficiency of the blast furnace in the operation of the blast furnace in which a non-burned coal-containing agglomerate ore is used as part of the blast furnace raw material and a reducing gas containing hydrogen is blown into the blast furnace, An object of the present invention is to provide a blast furnace operating method capable of suppressing the amount of CO ₂ generated.

That is, the gist of the present invention is as follows.
[1] In a method of operating a blast furnace in which a non-calcined coal-containing agglomerate ore is used as part of the blast furnace raw material and a reducing gas containing hydrogen is blown into the blast furnace, the amount of hydrogen in the bosh gas is set to X, and the non-calcined A method of operating a blast furnace characterized by operating within an operating region surrounded by the following formulas (1) to (3), where Y is the carbon content of the coal-bearing agglomerate ore.
(1): Y=−0.06X+29.07
(2): X=0
(3): Y=0
In the formula, the unit of X is Nm ³ /t-pig and the unit of Y is % by mass.
[2] According to the following relational expressions (a) to (c), according to the hydrogen content X in the bosh gas, the carbon content Y' derived from the non-burnt coal-containing agglomerate ore is adjusted according to [1] Blast furnace operating method.
(a): when X ≤ 140, Y' ≤ 0.2 x 160
(b): Y′≦0.15×160 when 140<X≦220
(c): when 220<X, Y′≦0.1×160
In the formula, the unit of X is Nm ³ /t-pig and the unit of Y' is kg/t-pig.
[3] In the method of operating a blast furnace in which pulverized coal is blown through a tuyere together with the reducing gas, the hydrogen content X in the bosh gas is included in the reducing gas in addition to the hydrogen gas content x ₁ in the reducing gas. [ ₁ ] which is the sum of the hydrogen gas amount x2 derived from the hydrocarbon component and the hydrogen gas amount _x3 derived from the hydrogen component and the hydrocarbon component contained in the pulverized coal (X=x1 ₊ x2 _{+ x3} ), or [2] The method for operating a blast furnace.
[4] The method for operating a blast furnace according to any one of [1] to [3], wherein the reducing gas is blown so that the hydrogen content X in the bosh gas is 300 Nm ³ /t-pig or less.
[5] The method for operating a blast furnace according to any one of [1] to [4], wherein the carbon content Y of the non-calcined coal-containing agglomerate ore is 25% by mass or less.

According to the present invention, the efficiency of the blast furnace can be increased in the operation of using the unburned coal-containing agglomerate ore as part of the blast furnace raw material and blowing a hydrogen-containing reducing gas into the blast furnace, and Since it becomes possible to suppress the consumption of carbon, the amount of CO ₂ generated can be suppressed.

FIG. 1 is a schematic diagram for explaining a blast furnace reaction simulator used in experimental examples. FIG. 2 is a graph showing the results of a blast furnace operation experiment using a blast furnace reaction simulator. FIG. 3 is a quadratic curve approximation of a part of the graph in FIG. 2 (in the case of formulation 5). FIG. 4 is a quadratic curve approximation of a portion of the graph in FIG. 2 (in the case of formulation 4). FIG. 5 shows the operation area obtained from the results of the blast furnace operation experiment.

The present invention will be described in detail below.
In the present invention, in a blast furnace operating method in which non-burned coal-containing agglomerate ore is used as part of the blast furnace raw material and a reducing gas containing hydrogen is blown into the blast furnace, the amount of hydrogen in the bosh gas is set to X, Assuming that the carbon content of the calcined coal-containing agglomerate ore is Y, the operation is carried out within the operating range defined by the following formulas (1) to (3).
(1): Y=−0.06X+29.07
(2): X=0
(3): Y=0
In the formula, the unit of X is Nm ³ /t-pig and the unit of Y is % by mass.

The operating range as described above was determined based on experimental results using a blast furnace reaction simulator. The details will be described later in Examples, but the reason why such a relationship is shown between the amount of carbon contained in the unburned coal-containing agglomerate ore and the amount of blown reducing gas is considered as follows. be done.

First, non-calcined coal-containing agglomerated ore is generally obtained by agglomerating fine powders of carbon materials such as coke and coal and fine powders of iron oxide using a hydraulic binder such as cement. Therefore, both carbonaceous materials and iron oxides are highly reactive. Moreover, since the fine carbonaceous material and the fine iron oxide powder are arranged close to each other in the non-fired coal-bearing agglomerate ore, carbon monoxide produced by the reaction of the carbonaceous material during blast furnace operation is Adjacent iron oxide is immediately reduced, and the produced carbon dioxide immediately reacts with the adjoining fine carbonaceous material. It is known that due to this synergistic effect, the activity in the blast furnace of non-calcined coal-containing agglomerate ore is much higher than that of sintered ore and coke.
C+ _CO2 →2CO
CO+FeO→Fe+ _CO2

However, when the amount of carbonaceous material is large in the unburned coal-containing agglomerate ore, or when a large amount of unburned coal-containing agglomerate ore itself is used, the carbon monoxide produced by the reaction in the blast furnace is oxidized. It is discharged out of the furnace without being used for iron reduction.

On the other hand, when a reducing gas containing hydrogen is blown into the blast furnace instead of a carbon-based reducing agent such as coke in order to suppress the generation of _CO2 , the carbonaceous material in the non-fired coal-containing agglomerate In addition to the reaction with carbon dioxide described above, as shown in the reaction formula below, the reaction with water vapor (H ₂ O) generated by reduction (water gasification reaction) also proceeds, so reducing gas is not blown. More hydrogen and carbon monoxide are produced than would otherwise be the case. And if this hydrogen and carbon monoxide are not effectively utilized for the reduction of iron oxide, the efficiency of the blast furnace will rather decrease.
C+ _H2O →H2 ₊ CO

In other words, when using non-burnt coal-containing agglomerate ore when blowing reducing gas into the blast furnace, the reaction between the carbonaceous material in the non-burning coal-containing agglomerate ore and the water vapor derived from the reducing gas causes more of CO and H2 _are generated. Therefore, by effectively using this reducing gas to reduce other blast furnace raw materials such as _sintered ore, it is possible to increase the efficiency of the blast furnace and obtain pig iron. ) is suppressed.

According to the results of an experiment simulating actual blast furnace operation using a blast furnace reaction simulator conducted in the present invention, it was found that non-burned coal-containing agglomerate ore was used as part of the blast furnace raw material, and reducing gas containing hydrogen was added to the blast furnace. In the blast furnace operation method of blowing into the inside, when the amount of hydrogen in the bosh gas is X and the amount of carbon derived from the unburned coal-containing agglomerate ore is Y′, the blast furnace is operated according to the following relational expressions (a) to (c). It turns out that it is better to do
(a): when X ≤ 140, Y' ≤ 0.2 x 160
(b): Y′≦0.15×160 when 140<X≦220
(c): when 220<X, Y′≦0.1×160

Among these units, the unit of the amount of hydrogen X in the bosh gas is Nm ³ /t-pig, and the unit of the amount of carbon Y' derived from the unburned coal-containing agglomerate ore is kg/t-pig. In this experiment, five types of unburned coal-containing agglomerate ore with a carbon content in the range of 0 to 20% by mass were prepared in increments of 5% by mass. Reducing gases with different hydrogen contents were injected into a blast furnace reaction simulator, and the inflection point at which the amount of carbon reduction, which increases with increasing hydrogen content, turns to decrease was determined. Based on this result, when the amount of hydrogen X in the bosh gas is 140 Nm ³ /t-pig or less, the amount of carbon Y' derived from the unburned coal-containing agglomerate ore is set to 32 kg/t-pig at maximum. It's good. Similarly, when the amount of hydrogen X in the bosh gas is from more than 140 Nm ³ /t-pig to 220 Nm ³ /t-pig or less, the maximum amount of carbon Y′ derived from unburned coal-containing agglomerate ore is 24 kg/t-pig. When the amount of hydrogen X exceeds 220 Nm ³ /t-pig, the amount of carbon Y' should be 16 kg/t-pig at maximum.

Here, "160" in the formula of the carbon content Y' in the above relational expressions (a) to (c) represents the charging amount (kg) of unburned coal-bearing agglomerate ore per 1 ton of pig iron, Each of the relational expressions (a) to (c) is multiplied by the ratio (carbon content) of the carbonaceous material in the non-calcined coal-containing agglomerate ore. The reason for using the amount of hydrogen X in the bosh gas is that, in addition to the hydrogen gas contained in the reducing gas, the hydrocarbon component contained in the reducing gas, or when pulverized coal is blown from the tuyere with hot air. This is because the hydrocarbon component decomposes at the tip of the tuyere to generate hydrogen gas together with carbon monoxide. Details of how to calculate the amount of carbon reduction, where the amount of carbon reduction increases as the amount of hydrogen in the Bosch gas increases, and how to find the inflection point where it starts to decrease are as explained in the examples. be.

The above equation (1) is obtained based on the inflection point obtained by this experiment, that is, the inflection point at which the amount of carbon reduction, which increases as the amount of hydrogen increases, turns to decrease. Since this formula (1) represents the boundary line where the amount of carbon reduction increases as the amount of hydrogen increases, when the amount of hydrogen in the bosh gas is X and the carbon content of the unburned coal-containing agglomerate ore is Y, , the hydrogen content X in the bosh gas and the carbon content of the unburned coal-bearing agglomerate ore within a range that does not exceed the boundary line of formula (1) [that is, within the operating area surrounded by formulas (1) to (3)] Y should be adjusted.

In the present invention, the amount of hydrogen X in the bosh gas does not reduce the efficiency of the blast furnace and suppresses the amount of CO ₂ generation as long as it is within the operation region surrounded by the formulas (1) to (3) as described above. However, hydrogen reduction generates less heat than CO reduction, and if it is blown excessively, the heat in the blast furnace will be insufficient, and the effect will be reduced. The amount of hydrogen X in the gas should be 300 Nm ³ /t-pig or less, more preferably 250 Nm ³ /t-pig or less. Here, in addition to the hydrogen gas amount x ₁ in the reducing gas, the hydrogen gas amount X in the reducing gas is the hydrogen gas amount x ₂ generated by decomposition of the hydrocarbon component when the reducing gas has a hydrocarbon component. (X = x ₁ + x ₂ ), and when pulverized coal is blown from the tuyere, the hydrogen gas amount x ₃ generated by decomposition of the hydrogen component and hydrocarbon component contained in the pulverized coal is It further contains (X = x ₁ + x ₂ + x ₃ ), and furthermore, although it is an extremely small amount, it further contains an amount of hydrogen gas x ₄ generated by decomposition of the hydrogen component contained in the coke (X = x ₁ + x ₂ + x ₃ + x ₄ ). In addition, since the present invention relates to the operation of blowing a reducing gas containing hydrogen into the blast furnace, the amount of hydrogen X in the bosh gas may be a significant amount exceeding 0, but the effect is From the viewpoint of expression, it is preferably 30 Nm ³ /t-pig or more.

As for the carbon content Y of the non-calcined coal-containing agglomerate ore, as in the case of the hydrogen content X, it is sufficient if it is within the operation range surrounded by the formulas (1) to (3). When the ratio of carbonaceous materials in the ore is excessively increased, the amount of CO generated increases due to the gasification of the highly reactive carbonaceous materials contained therein, while the ratio of the highly reducible iron oxides contained therein decreases, resulting in gasification. Considering the possibility that the reduction by CO gas may not be effectively utilized, the carbon content Y of the non-calcined coal-containing agglomerate ore is preferably 25% by mass or less. Regarding this carbon content Y, in the present invention, since the non-burned coal-containing agglomerate ore is used as part of the blast furnace raw material, the carbon content Y in the non-burnt coal-containing agglomerate ore exceeds 0. However, considering the expression of the effect, it is preferably 5% by mass or more.

In the present invention, the reducing gas to be blown into the blast furnace is not particularly limited as long as it contains hydrogen. For example, pure hydrogen, coke oven gas, natural gas, etc. can be used. However, coke oven gas and natural gas require so _- called decomposition heat to decompose the hydrocarbons contained in them into CO and _H2 . Also, the reducing gas is generally blown from the tuyeres, but may be blown into the blast furnace from the shaft or other places.

Moreover, the non-calcined coal-containing agglomerate ore is not particularly limited as long as it is used for operation of a blast furnace. In general, non-calcined coal-bearing agglomerate ore consists of finely powdered iron-containing raw materials containing iron (iron oxide) such as ironmaking dust such as sintering dust and blast furnace dust, and coal such as coke, anthracite, coke dust and coal char. In addition to the finely powdered carbon material-containing raw material containing the carbonaceous material, using a blended raw material containing a hydraulic binder having hydraulic properties such as portland cement, high-early strength portland cement, alumina cement, blast furnace cement, etc. After adjusting the moisture content of such a blended raw material, it can be obtained by molding into an agglomerate and curing it. The blending amount of the carbon material-containing raw material at that time is as described above.

In the present invention, other than operating within a predetermined operating area as described above, the operation can be performed in the same manner as a known blast furnace, and there is no particular limitation.

Hereinafter, the present invention will be specifically described based on examples. In addition, this invention is not restricted to these contents.

(Experimental example)
A blast furnace operation experiment was conducted using a blast furnace reaction simulator. This blast furnace reaction simulator (also called BIS furnace) is a device that can evaluate and simulate reduction and heat transfer in the countercurrent reaction of gas and solids in terms of the reaction efficiency of the blast furnace shaft. , the effects of exothermic reactions, endothermic reactions, and gas temperature rises in the blast furnace on internal samples can be reproduced with high accuracy (Nobuaki Naito et al., Technology for improving reaction efficiency in blast furnaces by using highly reactive coke, Iron Tokogane, Vol.87(2001), No.5, p.357-364, Fig.2).

Specifically, as schematically shown in FIG. 1, iron oxide (generally sintered ore), which is a material to be reduced, is placed in the reaction tube 1. A mixture of coal-bearing agglomerate ore) and coke as a reducing agent are alternately filled in layers, and an electric furnace 6 (consisting of a heating furnace 4 and an adiabatic furnace 5) arranged on the outer periphery of the reaction tube 1 is placed on the reaction tube 1. While moving from the top to the bottom in the longitudinal direction, the reaction gas is introduced from the gas introduction port 7 at the top of the reaction tube 1, passed through the plurality of iron oxide layers 2 and the coke layers 3, and passed through the gas discharge port at the bottom of the reaction tube 1. 8 is a countercurrent moving bed type reaction test apparatus. Among them, the reaction tube 1 is a stainless steel tube having an inner diameter of 103 mm and a length of 5.4 m. The electric furnace 6 preheats the reaction gas to the temperature (1200°C) of the upper part of the blast furnace cohesive zone, and the heating furnace 4 for completing the reduction of iron oxide, and the reaction below this temperature proceeds in an adiabatic system. It is composed of an adiabatic furnace 5 for The lengths of the heating furnace 4 and the adiabatic furnace 5 are 950 mm and 1090 mm, respectively.

As described above, in the blast furnace reaction simulator, iron oxide and coke are charged into the reaction tube 1 in layers, and the electric furnace 6 descends from the upper end of the reaction tube 1 toward the lower end at the same time as the reaction gas (bosch gas in the actual machine) equivalent) from the upper end of the reaction tube 1, a pseudo countercurrent moving bed can be reproduced.

In this experimental example, an iron oxide layer 2 made of approximately 0.5 kg of iron oxide and a coke layer 3 made of approximately 0.1 kg of coke are alternately arranged with respect to the reaction tube 1 of the blast furnace reaction simulator. The reaction tube 1 as a whole was filled with 35 kg of iron oxide and 7 kg of coke. Of these, as the iron oxide that is the material to be reduced, non-burning coal-containing agglomerate ore and sintered ore are used. Iron oxide layer 2 was obtained by mixing agglomerate: sintered ore at a ratio of 1:9.

Here, the non-calcined coal-containing agglomerate ore is obtained by using sintered powder as an iron-containing raw material, coke powder as a carbonaceous-containing raw material, and high-speed cement as a hydraulic binder. It has the chemical components shown in Table 1, and the particle size is 150 µm or less. In addition, as shown in Table 2, four kinds of materials (mixtures 1 to 4) were prepared by changing the content of coke powder as a carbonaceous material. Then, each blended raw material is kneaded while adjusting the moisture content by adding water, granulated with a pan pelletizer to produce raw pellets having a particle size of about 10 to 15 mm, and then cured at room temperature for 14 days or more. did. Table 3 shows analytical values of non-calcined coal-containing agglomerate ore obtained in each formulation. Of these, TC corresponds to the carbon content Y of the non-calcined carbon-containing agglomerate ore.

As described above, the iron oxide layer 2 is formed with the sintered ore while using the non-calcined coal-bearing agglomerate ore with a different composition, and the coke layer 3 and the reaction tube 1 alternately arranged are subjected to the following three conditions. The reaction gas was introduced from the gas inlet 7 with the gas composition under the condition. After reacting with iron oxide and coke, exhaust gas discharged from the gas outlet 8 (corresponding to furnace top exhaust gas in an actual furnace) was subjected to gas component analysis.
<Condition 1>
CO: 38% by volume, H2: ₃ % by volume, _N2 : 59% by volume
<Condition 2>
CO: 40.1% by volume, H2: _11.2 % by volume, _N2 : 48.7% by volume
<Condition 3>
CO: 41.7% by volume, H2: 18.7% by _volume , _N2 : 39.6% by volume

Of these conditions, conditions 2 and 3 simulate the blowing of reducing gas containing hydrogen into the blast furnace, while condition 1 represents no such blowing. That is, condition 1 is the basic condition of the reaction gas in this experimental example, and the reducing agent ratio under condition 1 is 481 kg/t. However, although the condition 1 contains 3% by volume of hydrogen gas, this assumes that pulverized coal is blown into the blast furnace, and the hydrogen gas generated by decomposition of the hydrocarbon components contained in the pulverized coal. The amount is 3% by volume, and conditions 2 and 3 also take this 3% by volume into consideration. The amount of reaction gas blown (reactant gas amount) under conditions 1 to 3 was 22.1 Nm ³ /min.

In this experimental example, the electric furnace 6 was moved downward by about 250 mm/h while blowing the reaction gas under the above conditions into the reaction tube 1 filled with the predetermined iron oxide layer 2 and coke layer 3. While simulating the movement of the charge, the reaction due to countercurrent movement was simulated. The electric furnace 6 is composed of a heating furnace 4 and an adiabatic furnace 5 . The temperature of the heating furnace 4 is set at 1200° C. and is a region for superheating the charge, while the adiabatic furnace 5 is a region for simulating the shaft portion in the blast furnace. The adiabatic furnace 5 is divided into 10 sections in the height direction, and has a structure that prevents heat dissipation from the reaction tube by controlling the temperature difference between the inside and outside of the reaction tube at each position. At that time, while the electric furnace 6 was descending, the gas composition and temperature were measured at a fixed position inside the reaction tube 1 (a position approximately 1.4 m from the lower end). The temperature and gas composition here are used to analyze changes in furnace temperature and reaction accompanying the use of non-calcined coal-bearing agglomerate ore. It was obtained by calculating the reducing gas utilization rate ηCO from the analytical value of the exhaust gas component from the gas outlet 8, which is the later top exhaust gas. After a predetermined time (about 3 hours) has passed since the reaction in the reaction tube 1 reached a steady state and the exhaust gas components from the gas outlet 8 were analyzed, the sample inside the reaction tube 1 was taken. The experiment was terminated by cooling under flowing _N2 .

Here, the amount of iron oxide charged into the reaction tube 1 is constant at all levels, and when non-calcined coal-containing agglomerate ore is used, the amount of sintered ore charged is reduced by the iron content equivalent. Therefore, the amount of oxygen to be removed at all levels is constant. Therefore, _ηCO and _ηH2 , which are effective utilization rates of CO gas and H2 gas, can be obtained from the composition of the exhaust gas (equivalent to furnace top exhaust gas) from the gas outlet 8 when the reaction reaches a steady state. The amount of carbon required for reduction can be calculated from Higher utilization of this CO gas and _H2 gas will reduce the amount of carbonaceous material needed to remove oxygen. In this experimental example, non-calcined coal-containing agglomerate ores with different carbon contents were used. However, when the carbon content was 0% by mass, no non-calcined carbon-containing agglomerate ore was used, and sintered ore was used as the iron oxide source. Under the conditions of using non-calcined coal-bearing agglomerate ores with different carbon contents, the reaction gases under the above three conditions were blown into the reaction tube 1, and the required carbon content under each condition was obtained from the material balance described above. . Then, the amount of carbon material in the non-burned coal-containing agglomerate ore was increased based on the required amount of carbon under condition 1, which is the basic condition for blowing in the reaction gas, without using the non-burned coal-containing agglomerate ore. The amount of carbon reduction was calculated from the difference between the amount of carbon required under each condition and the amount of hydrogen injected under different conditions.

FIG. 2 summarizes the results obtained in this experimental example. In the graph of FIG. 2, the vertical axis represents the carbon reduction amount Y″ (kg/t-pig), and the horizontal axis represents the injected hydrogen ratio X″ (Nm ³ /t-pig). Of these, the carbon reduction amount Y″ is as described above, and the blown hydrogen ratio X″ is the amount of reaction gas blown (22.1 Nm ³ /min) and the above reaction gas blow conditions 1 to 3. The ratio of hydrogen gas is obtained from each hydrogen gas amount, and these are plotted.

As can be seen from the graph in FIG. Along with this, the amount of carbon reduction increases proportionally. This is the same when using the non-calcined carbon-containing agglomerate ores of mixtures 1 and 2, but with the non-calcined carbon-containing agglomerate ores of mixtures 3 and 4, the increase in carbon reduction amount tends to slow down. Specifically, in combination 3, in which the carbon content Y is 14.90% by mass, which is the same as in combination 4, in which the carbon content Y in the non-calcined coal-containing agglomerate ore is 19.60% by mass, hydrogen gas in the reaction gas As the amount was increased, after a predetermined amount of hydrogen gas, the amount of carbon reduction tended to fall below that in the case of not using non-calcined carbon-containing agglomerate ore.

Regarding such a tendency, when the graphs of formulations 4 and 3 in FIG. 3 and 4 are the intersection points of . That is, according to FIG. 3, when the injected hydrogen ratio reaches 140 Nm ³ /t-pig, the carbon reduction efficiency of compound 4 decreases thereafter. Further, according to FIG. 4, when the injected hydrogen ratio reaches 220 Nm ³ /t-pig, the carbon reduction efficiency of Blend 3 decreases thereafter. Based on these results, it can be seen that it is preferable to operate according to the following relational expressions (a) to (c). ' should be adjusted.
(a): when X ≤ 140, Y' ≤ 0.2 x 160
(b): Y′≦0.15×160 when 140<X≦220
(c): when 220<X, Y′≦0.1×160
In the formula, the unit of X is Nm ³ /t-pig and the unit of Y' is kg/t-pig.

Also, based on the results obtained above (results shown in FIGS. 3 and 4), the relationship shown in FIG. 5 can be derived. That is, when the amount of hydrogen in the bosh gas is X and the carbon content of the unburned coal-containing agglomerate ore is Y, if the operation is performed within the operating range defined by the following formulas (1) to (3): good. In FIG. 5, the amount of hydrogen X in the bosh gas is shown up to 250 Nm ³ /t-pig, but even considering the amount of reducing gas blown in the actual operation, this is sufficient. I can say
(1): Y=−0.06X+29.07
(2): X=0
(3): Y=0
In the formula, the unit of X is Nm ³ /t-pig and the unit of Y is % by mass.

As described above, according to the present invention, in a method for operating a blast furnace in which a non-calcined coal-containing agglomerate ore is used as part of the blast furnace raw material and a reducing gas containing hydrogen is blown into the blast furnace, the non-calcined coal-containing agglomerate ore is While making effective use of reducing gases such as CO and H2 generated from agglomerate ore, the efficiency of the blast furnace can be increased to obtain pig iron, and the amount of _{CO2 generated} can be suppressed. become.

1: reaction tube, 2: iron oxide layer, 3: coke layer, 4: heating furnace, 5: adiabatic furnace, 6: electric furnace, 7: gas inlet, 8: gas outlet.

Claims (5)

In a method of operating a blast furnace in which unburned coal-containing agglomerate ore is used as part of the blast furnace raw material and a reducing gas containing hydrogen is blown into the blast furnace, the amount of hydrogen in the bosh gas is set to X, and the unburned coal-containing agglomerate is A blast furnace operating method characterized by operating within an operating region surrounded by the following formulas (1) to (3), where Y is the carbon content of the ore.
(1): Y=−0.06X+29.07
(2): X=0
(3): Y=0
In the formula, the unit of X is Nm ³ /t-pig and the unit of Y is % by mass. The blast furnace operating method according to claim 1, wherein the carbon content Y′ derived from the unburned coal-containing agglomerate ore is adjusted according to the hydrogen content X in the bosh gas according to the following relational expressions (a) to (c). .
(a): when X ≤ 140, Y' ≤ 0.2 x 160
(b): Y′≦0.15×160 when 140<X≦220
(c): when 220<X, Y′≦0.1×160
In the formula, the unit of X is Nm ³ /t-pig and the unit of Y' is kg/t-pig. In the blast furnace operation method in which pulverized coal is blown into the tuyere together with the reducing gas, the amount of hydrogen X in the bosh gas is, in addition to the amount of hydrogen gas x ₁ in the reducing gas, the hydrocarbon component contained in the reducing gas. 3. The sum of the hydrogen gas amount x ₂ derived from and the hydrogen gas amount x ₃ derived from the hydrogen component and the hydrocarbon component contained in the pulverized coal (X = x ₁ + x ₂ + x ₃ ) according to claim 1 or 2 blast furnace operation method. The blast furnace operating method according to any one of claims 1 to 3, wherein the reducing gas is blown so that the amount of hydrogen X in the bosh gas is 300 Nm ³ /t-pig or less. The method for operating a blast furnace according to any one of claims 1 to 4, wherein the carbon content Y of the non-calcined coal-containing agglomerate ore is 25% by mass or less.

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