JP2003301205A - Method for charging blast furnace material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for charging blast furnace materials, which enhances a gas utilization factor to the maximum, and reduces a fuel ratio without deteriorating permeability of the air and a liquid, by using agglomerated ore including carbonaceous materials, even under the condition that the charge weight of the agglomerated ore including the carbonaceous materials is limited particularly in a blast furnace operation of blowing a large quantity of auxiliary fuels. <P>SOLUTION: When alternately charging the blast furnace materials such as sintered ore, pellets and massive ore, and cokes so as to form layers, into a blast furnace into which the auxiliary fuels of 100 kg or more per 1 t of pig iron are determined to be blown, this charging method is characterized by making a half or thinner part of a thickness of the raw material layer spreading from the top of each raw material layer consisting of the blast furnace materials to the bottom part, include the agglomerated ore containing the carbonaceous materials obtained by means of hot compacting a mixture containing fine ore and coal powders having the Gisella maximum fluidity (MF) satisfying log MF≥1.0, in a range of 300-550°C. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blast furnace raw material charging method, and more particularly to a blast furnace raw material charging method suitable for maintaining the stability of the operation during the operation of blowing a large amount of pulverized coal.

[0002]

2. Description of the Related Art In a blast furnace operation, blast furnace raw materials (lump iron oxide raw materials) such as sinter, pellets (calcined pellets) and lump ores and cokes (lump carbonaceous materials) are charged alternately in layers. During the charging, the mass ratio of ore and coke in the radial direction of the furnace (hereinafter this ratio is abbreviated as O / C) is controlled with high accuracy, and the gas flow distribution in the furnace, the cohesive zone shape, etc. It is important to maintain the temperature within the target range, that is, to properly secure the central flow in order to achieve stable operation of the blast furnace.

Conventionally, in order to control the O / C distribution in the radial direction in the furnace, in a blast furnace equipped with a bell-type charging device, it is necessary to properly control the set position of the movable armor, and also to use the bell-less type charging device. It has been practiced to adjust the tilt angle of the distribution chute in a blast furnace equipped with a charging device.
Recently, a method has been proposed in which a charging chute of another route is installed side by side and the charging chute directly charges the blast furnace raw material and / or coke into the center of the blast furnace. By properly using these methods and controlling the O / C distribution in the furnace radial direction with high accuracy, the gas utilization rate [η CO = CO ₂ / (CO + CO ₂ ) × 100] can be controlled while controlling the gas flow. It is said that the fuel ratio of the blast furnace (fuel mass required to produce 1 ton of pig iron) can be improved.

The blast furnace raw material is heated and heated by the reducing gas rising in the furnace to be reduced in the process of descending in the furnace after entering the furnace interior. Figure 1 shows changes in temperature and gas components in the typical height direction of the blast furnace. Also, each raw material layer has a layer thickness of 30 to
Since it is 150 cm, as shown in Fig. 2, there is a component change in the layer thickness direction in each raw material layer, and the CO potential of gas (= CO / (CO + CO ₂ )) is lower in the upper portion of the raw material layer. Inevitably lower than. Therefore, the reduction of the ore existing in the upper part of each raw material layer is delayed and the reduction rate is lowered, which is likely to cause a blast furnace malfunction such as a downfall.

The coke layer thickness has a lower limit in order to ensure air permeability in the cohesive zone. On the other hand, when a large amount of pulverized coal (auxiliary fuel) is blown in, which has been vigorously carried out in recent years, in order to maintain the fuel ratio (= coke ratio + pulverized coal (auxiliary fuel) ratio), the furnace top is installed. It is necessary to reduce the amount of coke entering. Therefore, in order to carry out a large-scale pulverized coal (auxiliary fuel) blowing operation, there is no choice but to increase the O / C, which inevitably increases the raw material layer thickness. Therefore, the reduction delay in the upper part of the raw material layer becomes more prominent and the operation of the blast furnace becomes unstable. Therefore, it is the current situation that the fuel ratio must be increased in order to avoid operational troubles.

In addition, when a large amount of pulverized coal (auxiliary fuel) is blown in, the amount of solids charged from the furnace top decreases, so that the heat flow ratio [heat capacity of solids / heat capacity of gas] decreases and the furnace top temperature increases. The fuel ratio rises due to problems such as a further increase in heat loss from the furnace wall and furnace top, and an increase in the dust ratio due to the scattering of dust that was not scattered until now. Are also coming out (prior art 1).

On the other hand, by improving the reducibility of the blast furnace raw material and mixing it with the conventional blast furnace raw material such as sinter or pellets, the reduction of the respective raw material layers in the layer thickness direction is promoted. Various proposals have been made to stabilize the blast furnace operation and reduce the fuel ratio.

For example, a solid carbonaceous material (for example, coal powder, coke powder, etc.) and powdered ore or dust (mixture of carbon, iron oxide, etc.) with a binder added thereto, and cold-formed carbonaceous material-containing cold bond pellets or composites. What is called is proposed (see Japanese Patent Publication No. 1-28085, Japanese Patent No. 2600803, Japanese Patent Laid-Open No. 60-262907, etc.). It has been reported that the use of cold bond pellets containing carbon material improves the gas utilization rate [Inoue et al .: Iron and Steel (1986), S885]. However, when cements are used as a binder in the production of carbonaceous material cold bond pellets or composites, during the reduction in the blast furnace, the water of crystallization in the cements is decomposed or decarboxylated, and the iron oxides are transformed. As a result, the strength is reduced and the powder is pulverized to deteriorate the air permeability. Furthermore, there is a concern that the liquid permeability may deteriorate because the slag ratio in the blast furnace increases. In addition, since the strength of the cold bond pellets is expressed after molding, there is a problem that a vast site for curing the pellets and a long time are required. On the other hand, if this is improved and a binder other than cement is used, the cost is high and the cost merit is lost (prior art 2).

Therefore, the present inventors have prepared a carbonaceous material-containing agglomerated ore obtained by molding a mixture of powdered ore and coal powder at a temperature of 350 to 550 ° C. We have developed a method of charging the blast furnace raw material and charging it into the blast furnace (JP 2000
-290709). According to this method, since compression molding is performed at the time of softening and melting of coal powder, and thereafter solidified, binders such as cements are unnecessary while securing sufficient strength, so the liquid permeability does not increase the slag ratio. There is no worsening problem. In addition, since the carbon solidified after melting in the agglomerated ore containing carbonaceous materials and the ore are in close contact, the reduction reaction starts from the low temperature region in the blast furnace, and the gas generated by the reaction is mainly CO gas. Therefore, since it is used for the reduction of the raw materials such as the mixed sinter, pellets, and lump ore, the gas utilization rate can be improved and the fuel ratio can be reduced accordingly. It was also found that the reaction between coke charged as fuel and CO ₂ gas is suppressed, so that the amount of coke dust generated can be reduced and the air permeability in the blast furnace is improved (Prior Art 3).

[0010]

In the case of the method of the above-mentioned prior art 3, the fuel charged into the blast furnace is coke charged from the furnace top, auxiliary fuel blown from the tuyere, and carbon material-containing agglomerate. It is a carbonaceous material in the mine. Where the coke is
It plays a role of ensuring air permeability and liquid permeability in the blast furnace. Therefore, while maintaining or reducing the fuel ratio of the entire blast furnace, the amount of coke that can ensure the air permeability and liquid permeability in the blast furnace is charged, and the low cost auxiliary fuel (pulverized coal, waste plastic, tire scrap, etc.) In order to blow a large amount of carbonaceous material, the amount of carbonaceous material brought into the blast furnace is limited by the carbonaceous material-containing agglomerated ore. In other words, the charging amount of carbonaceous material agglomerated ore will be limited. Therefore, there has been a demand for the development of a charging method capable of maximally reducing the fuel ratio and stabilizing the operation even with such a limited charging amount of the carbonaceous material-containing agglomerated ore.

Therefore, an object of the present invention is to use the above-described carbonaceous material-containing agglomerated ore even under conditions where the charging amount of the carbonaceous material-containing agglomerated ore is limited particularly in a blast furnace operation in which a large amount of auxiliary fuel is blown. The present invention provides a blast furnace raw material charging method capable of maximizing the gas utilization rate without deteriorating ventilation and liquid permeability and reducing the fuel ratio.

[0012]

In order to achieve the above object, the gist of the blast furnace raw material charging method according to the present invention is as follows.

According to a first aspect of the present invention, there is provided a raw material charging method of alternately charging the massive iron oxide raw material and the massive carbonaceous material into the blast furnace in a layered manner. In the part of the thickness of 1/2 or less of the raw material layer to reach,
It is a method for charging a blast furnace raw material, characterized by including a carbonaceous material-containing agglomerated ore.

According to a second aspect of the invention, the carbonaceous material-containing agglomerate comprises a mixture containing a powdery iron oxide-containing substance and a powdery carbonaceous material.
The blast furnace raw material charging method according to claim 1, which is obtained by hot forming in a temperature range of 0 to 550 ° C.

A third aspect of the present invention is the method for charging a blast furnace raw material according to the second aspect, wherein the Giesella maximum fluidity (MF) of the pulverized coal is log MF ≧ 1.0.

[0016] In the invention of claim 4, the carbon content in the carbon material-containing agglomerated ore is 0.5 times or more of the theoretical carbon amount necessary for reducing the iron oxide in the carbon material-containing agglomerated ore. The blast furnace raw material charging method according to claim 2 or 3.

According to a fifth aspect of the present invention, after the hot forming and before charging the blast furnace, the carbonaceous material-containing agglomerate is held at a temperature of the hot forming temperature or more for 5 minutes or more to remove tar. The blast furnace raw material charging method according to any one of claims 2 to 4, wherein treatment is performed.

The invention of claim 6 has a mass ratio of 4 or more to the total amount of the massive iron oxide raw material and the carbonaceous material-containing agglomerated ore and the massive carbonaceous material. The blast furnace raw material charging method according to item 1.

A seventh aspect of the present invention is the blast furnace raw material charging method according to any one of the first to sixth aspects, wherein the blast furnace is a blast furnace having an auxiliary fuel injection amount of 100 kg or more per ton of pig iron.

[Operation] According to the present invention, a carbonaceous material-containing agglomerate containing iron oxide and carbon as main components is formed in a portion having a thickness of 1/2 or less of the thickness of the raw material layer from the upper surface of each raw material layer to the lower side. (Claim 1). This allows
If the raw material layer is heated to a predetermined temperature, the reduction proceeds sufficiently even in the lower part of the raw material layer where the CO potential of the gas is high, even if only massive iron oxide such as conventional sinter, pellets, ore ore, etc. The reduction of the carbonaceous material-containing agglomerated ore progresses even in the upper part of the raw material layer where the CO potential of CO To do. As a result, the gas utilization rate is improved and the fuel ratio is reduced. In addition, since the carbon content inside the carbonaceous material agglomerated ore is preferentially used, the reaction between the massive carbonaceous material charged as fuel and CO ₂ gas is suppressed,
Since the amount of powdered lump carbonaceous material is reduced, the air permeability in the blast furnace is improved. The reason why the range of including the carbonaceous material-containing agglomerate was set to be 1/2 or less of the raw material layer thickness is that if the range is made too large, the ratio of the carbonaceous material-containing agglomerate contained in the raw material layer decreases. This is because the effect of accelerating the reduction of blast furnace raw materials by the gas mainly composed of CO gas generated from the carbonaceous material agglomerated ore becomes too small.

According to the prior art 3, the carbonaceous material-containing agglomerated ore similar to that of the present invention is mixed with lumped iron oxide such as sinter, pellets and lump ore, and then charged into the blast furnace. Therefore, the carbonaceous material-containing agglomerates are uniformly contained in the entire thickness direction of the raw material layer. Therefore, as compared with the present invention, the proportion of carbonaceous material-containing agglomerates existing in the upper part of the raw material layer having a low CO potential is small, and the amount of CO-based gas generated is also small. Not promoted enough.

Further, it is desirable to use, as the carbonaceous material-containing agglomerate, a mixture of powdered iron oxide and powdered carbonaceous material that has been hot-formed at a temperature of 300 to 550 ° C. (claim 2). ). By utilizing the caking property developed when powdered carbonaceous material is heated without using a binder by hot forming,
Sufficiently high density and high crush strength (400N / piece or more;
This is because it can be an agglomerated ore containing carbon material (described later).
The reason why the heating temperature is in the range of 300 to 550 ° C. is as follows. That is, in general, the powdery carbonaceous material starts to soften at 300 ° C. or higher, and the fluidity increases as the temperature rises. However, since solidification also begins at the same time, the maximum fluidity is reached at a given temperature, and when the temperature further rises, the solidification becomes dominant and the fluidity decreases, and when it exceeds 550 ° C, the solidification progresses rapidly. This is because the liquidity is lost. In addition, it is preferable to perform pressure molding at a temperature in the vicinity of the temperature at which the maximum fluidity is exhibited (it varies depending on the type of carbonaceous material) because the carbonaceous material-containing agglomerate becomes denser and the crushing strength becomes higher. In addition, since the carbonaceous material-containing agglomerated ore is agglomerated without using a binder, unlike the carbonaceous material-containing cold bond pellets or composites that are manufactured using a binder, there is no need to worry about the high cost of using a binder. Moreover, there is no problem of deterioration of liquid permeability due to increase in slag ratio, which is a problem when cements are used as a binder. Further, by using a carbonaceous material-containing agglomerated ore having a high crushing strength, generation of powder, which is a problem from the viewpoint of air permeability of the blast furnace, can be suppressed. In addition,
Most of the volatile components and tar components contained in the powdery carbonaceous materials are devolatilized and detarred during hot forming, and the proportion of carbonaceous materials in the carbonaceous material-containing agglomerate is at most about At about 30% by weight,
Since the amount of the carbonaceous material-containing agglomerate charged into the blast furnace is small, even if the carbonaceous material-containing agglomerate is charged into the blast furnace, the adhesion of tar to the equipment does not pose a problem.

As the powdery carbonaceous material, it is preferable to use a powdery carbonaceous material having a Giesella maximum fluidity (MF) of logMF ≧ 1.0 (claim 3), and it is preferable to use a powdery carbonaceous material of logMF ≧ 2.0. Particularly preferred. When the carbonaceous material-containing agglomerated ore using the powdery carbonaceous material having such a high fluidity is used, the coal having a higher density and crushing strength is utilized by utilizing the caking property developed when the powdery carbonaceous material is heated. This is because the material-containing agglomerate can be obtained, and by mixing it with other raw materials and charging it into the blast furnace, the above-mentioned effects can be obtained. As shown in FIG. 3,
By setting MF to logMF ≧ 1.0, the crushing strength of the carbonaceous material agglomerated ore can be 400N / piece or more which can withstand handling such as blast furnace charging, and by setting logMF ≧ 2.0, the carbonaceous material agglomerated ore can be crushed. A crushing strength of 700 N / piece or more can be obtained, and pulverization in the blast furnace can be further suppressed. In order to obtain such an effect more effectively, in addition to the fact that the Giesella maximum fluidity (MF) is log MF ≧ 1.0 as the powdery carbonaceous material of the carbonaceous material agglomerate, It is preferable to raise the heating rate of coal at the time of hot forming at 10 ° C./sec or more.

Further, the carbon content in the carbonaceous material-containing agglomerate is preferably 0.5 times or more of the theoretical carbon amount necessary to reduce the iron oxide in the carbonaceous material-containing agglomerated ore. 4),
As a result, the reduction from the inside of the carbonaceous material-containing agglomerate and the reduction from the outer surface of the carbonaceous material-containing agglomerate by the reducing gas rising in the raw material layer proceed in parallel, so that a sufficient reduction rate can be obtained. Here, "theoretical carbon amount necessary to reduce iron oxide in carbonaceous material agglomerated ore" means that 1 mol of oxygen contained in iron oxide in carbonaceous material agglomerated ore is reduced. Is a value calculated from the chemical composition, assuming that 1 mol of carbon is required (for example, Fe ₂ O ₃ + 3C → 2Fe + 3CO). It should be noted that the greater the amount of carbon in the carbonaceous material-containing agglomerate, the greater the effect of promoting reduction, but if the carbon amount becomes excessive, the strength of the carbonaceous material-containing agglomerate decreases conversely. Therefore, the amount of carbon in the carbonaceous material-containing agglomerate is preferably 1.5 times or less the theoretical carbon amount, and recommended to be in the range of 0.7 to 1.2 times.

Further, it is preferable to carry out the detarring treatment by holding the carbonaceous material-containing agglomerate at a temperature higher than the hot forming temperature for 5 minutes or more after the hot forming and before charging the blast furnace (claim) Item 5). As described above, most of the volatile components and tar components contained in the powdered carbonaceous materials are devolatilized and tar-free during hot forming, so heat treatment is not performed without such detarring treatment. Even if the carbonaceous material-containing agglomerate is charged into the blast furnace as it is during hot forming, the tar content does not pose a problem, but it is possible to make the carbonaceous material-containing agglomerate more efficient by detarring. It has the effect of densifying and further increasing the crushing strength, and more reliably preventing pulverization in the blast furnace.

In the present invention, the mass ratio (that is, O / C) of the aggregate iron oxide raw material and the carbonaceous material-containing agglomerate to the aggregate carbonaceous material is preferably 4 or more (claim) Item 6), whereby the carbonaceous material-containing agglomerate is placed (included) in the upper part of the raw material layer while ensuring a sufficiently high amount of auxiliary fuel injection, so the entire raw material layer thickness is sufficiently reduced. ,
There are no problems such as live birth. If the O / C is too high, the air permeability and liquid permeability will be impaired, so it is desirable to set it to 7 or less.

Further, in the present invention, it is preferable that the amount of the auxiliary fuel blown is 100 kg or more per ton of pig iron (claim 7), whereby high cost lumpy carbonaceous material can be substituted for low cost pulverized coal and the like. Fuel cost is reduced because a large amount of auxiliary fuel can be used.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. As a powdered iron oxide raw material, for example, T.Fe: about 68 mass% of powdered ore, and as a powdered carbonaceous material, for example, C: 80 mass% of coal powder at a mass ratio of about 78:22 (powdered ore: coal powder). After mixing, the mixture is heated to a temperature of about 440 ° C., and hot-formed into an egg-shaped carbonaceous material-containing agglomerated ore having a volume of about 6 cm ³ at a forming pressure of a linear pressure of about 2.5 t / cm. If necessary, this carbonaceous material-containing agglomerate may be detarred by holding it at a temperature higher than the molding temperature, for example, at a temperature of about 500 ° C. for 5 minutes or more.

Here, for example, in the case of a bell-armor type blast furnace, for the purpose of adjusting the O / C distribution in the radial direction in the blast furnace,
Usually, the coke is charged in layers and then several times (eg N
The method of charging the blast furnace raw material in two steps is adopted. Therefore, the first (N-
M) batch is charged with blast furnace raw material A consisting of sinter ore, pellets, lump ore, etc. as usual, and the remaining M batches are sinter, pellets, or lumps of the specified amount of carbonaceous material agglomerate. Blast furnace raw material B mixed with blast furnace raw material (lump iron oxide raw material) such as ore is charged. By changing the charging number M of the blast furnace raw material B mixed with the carbonaceous material-containing agglomerate in this manner, the thickness of the raw material layer containing the carbonaceous material-containing agglomerate can be easily adjusted. According to this method, the conventional charging equipment can be used as it is, and since the charging method does not have to be significantly changed, the present invention can be implemented at low cost.

In this example, the mixing ratio (mass ratio) of the powder ore and the coal powder was set to powder ore / coal powder = 78/22, but the amount of coal depends on the amount of carbon in the coal and the amount of Fe in the ore. Of theoretical carbon
The crushing strength may be adjusted to 0.5 times or more (particularly in the range of 0.7 to 1.2 times) so as to obtain a crushing strength of about 400 N / piece or more, which can withstand handling at the time of charging to the top of the blast furnace.

In this example, powdered ore was used as an example of the powdered iron oxide raw material, but the powdery iron oxide raw material is not limited to this, and blast furnace dust, converter dust, electric furnace dust containing iron oxide,
Mill scale, mill sludge, shredder dust, etc. can also be used. Further, as the powdery carbonaceous material, coal is exemplified in this example, but the present invention is not limited to this, and it is possible to use pitch, asphalt, SRC, etc., which contains carbon and exhibits softening / melting property by heating. it can.

The shape of the carbonaceous material-containing agglomerate is not particularly limited, and in addition to the egg shape of this example, a pillow shape, a spherical shape, a bale shape,
It may have a block shape, a cubic shape, or a rectangular parallelepiped shape. The lower limit of the size of the carbonaceous material-containing agglomerate is preferably 5 mm or more so as to maintain the air permeability of the raw material layer, but the upper limit is not particularly limited. This is because the internal carbonaceous material is also reduced from the inside, so that the particle size is not limited as in the case of sinter, pellets, agglomerated ores, etc., which is reduced only from the outer surface by the reducing gas. However, it is recommended that the diameter be 100 mm or less so that it can be mixed into the conventional blast furnace raw materials such as sinter, pellets, and lump ore as uniformly as possible without segregation.

Although the charging method by the bell armor method has been described in the present example, the same method can be applied to the bellless method. That is, even in a bellless blast furnace, a method of swirling a swirling chute multiple times is usually used when charging a blast furnace raw material. The carbonaceous material-containing agglomerated ore may be mixed only in.

By charging the blast furnace raw material B mixed with the carbonaceous material-containing agglomerate into a predetermined portion above the raw material layer as described above, the raw material layer descends in the blast furnace and is heated, and the carbonaceous material-containing lump is heated. Apparently direct reduction reaction (endothermic reaction) is initiated between coal and ore in the ore. Since the gas generated by this reduction reaction is mainly CO gas, it promotes the reduction of the blast furnace raw materials such as sinter ore, pellets, and lump ore, etc., which are mixed and charged into the carbonaceous material-containing agglomerated ore and which are located above the raw material layer. Therefore, the reduction efficiency of the entire thickness of the raw material layer is improved, and the fuel ratio is reduced. Further, since the carbonaceous material reacts preferentially with the CO ₂ gas, the reaction of charging coke and CO ₂ gas as a fuel is suppressed, the permeability of the blast furnace for powder generation amount of coke is reduced improving To do.

[0035]

[Example] [Example 1] Under reducing conditions simulating the inside of a blast furnace,
The reduction experiments of the carbonaceous material-containing agglomerated ore used in the present invention and the conventional sintered ore and pellets (calcined pellets) were conducted to compare the reduction conditions.

In the agglomerated ore containing carbonaceous material, the powdered ore shown in Table 1 and the coal powder shown in Table 2 were mixed at a mass ratio of 78:22 (powdered ore: coal powder), and the mixture was heated to a temperature of 440 ° C. Heated, twin roll type molding machine, linear pressure 2.5t / cm molding pressure 30mm × 25mm
It was hot-formed into an egg-shaped briquette (carbonaceous material-containing agglomerated ore) having a size of 17 mm (volume about 6 cm ³ ).

The sintered ore used had a particle size of 11.2 to 12.7 mm, and the fired pellet used had a particle size of about 12 mm.

The reduction experiment was carried out for each sample under a constant load (98 kPa) under the conditions of temperature rise and gas components shown in FIG. Briquette (carbonaceous material-containing agglomerated ore) was divided into four and subjected to reduction experiments.

[0039]

[Table 1]

[0040]

[Table 2]

FIG. 5 shows the result of the reduction experiment conducted for each sample. FIG. 5 shows the relationship between the ultimate temperature and the reduction rate at that time. As is clear from FIG.
It can be seen that the carbonaceous material-containing agglomerated ore is remarkably superior to the pellets and the sintered ore especially under the condition of low CO potential up to 1000 ° C. From this,
Place (include) carbonaceous material agglomerate on the upper side of the raw material layer
Thus, it was confirmed that the reduction of the reduction rate of the raw material in the upper part of the raw material layer having a low CO potential can be suppressed.

Example 2 Next, a carbonaceous material-containing agglomerate, a carbonaceous material-containing cold bond pellet, and a calcined pellet were subjected to reduction experiments under the methods and conditions different from those in Example 1, respectively. The changes in intensity were compared. The carbonaceous material-containing agglomerated ore and the fired pellets were the same as those used in Example 1 above. The briquette (carbonaceous material-containing agglomerated ore) was used as it was without being divided. The carbon material-containing cold bond pellets, like the carbon material-containing agglomerated ore, consist of powdered ore and coal powder.
78:22 (powder ore: coal powder) is mixed in a mass ratio, and 11.1 mass% of Portland cement is added to this,
An appropriate amount of water was added to pelletize a pellet having a diameter of about 12 mm, which was then sealed and cured for about 5 days. The reduction experiment is
Insert a sample into a heating furnace that is maintained at a constant temperature in the range of 1000 to 1200 ° C without applying a load to the sample.
The reduction time was variously changed within the range of 0 to 60 minutes for the 0 minute and fired pellets. The atmosphere in the heating furnace is different for carbonaceous material agglomerated ores and carbonaceous material cold bond pellets.
N ₂ : 100%, and in the fired pellet, N ₂ / CO = 50/50 (volume%). FIG. 6 shows the relationship between the reduction rate and the crush strength of each sample after reduction. As is clear from FIG. 6, the crush strength of the fired pellets is 1 / at a reduction rate of 20% compared to that before reduction.
It rapidly decreases to about 10, and the crush strength of the carbon material-containing cold bond pellets gradually decreases as the reduction rate increases, and the crush strength decreases to about 1/2 at the reduction rate of 40%.
On the other hand, it was confirmed that the crush strength of the carbon material-containing agglomerate hardly changed (reduced) during the reduction and maintained high strength. Therefore, by using the carbonaceous material-containing agglomerated ore, the pulverization of the raw material in the blast furnace is suppressed, and the air permeability in the furnace is improved or maintained.

[0043]

As described above, according to the blast furnace raw material charging method of the present invention, the reduction delay in the upper part of the raw material layer can be effectively prevented, so that the fuel ratio can be lowered. Further, since the blast furnace raw material and coke can be suppressed from being pulverized, the air permeability in the blast furnace is improved, so that the operation of injecting a large amount of auxiliary fuel into the blast furnace can be stably performed.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a temperature change and a gas component change in a typical height direction in a blast furnace.

FIG. 2 is a schematic diagram showing a temperature change, a gas component change, and a reduction rate change in a layer thickness direction in each raw material layer.

FIG. 3 is a graph showing the relationship between logMF of powdered carbonaceous material and crushing strength of carbonaceous material-containing agglomerated ore.

FIG. 4 is a diagram showing conditions of temperature rise and gas components in the reduction experiment of Example 1.

FIG. 5 is a graph showing the relationship between the ultimate temperature and the reduction rate in the reduction experiment of Example 1.

FIG. 6 is a graph showing the relationship between the reduction rate and the crush strength in the reduction experiment of Example 2.

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Claims (7)

[Claims] 1. A raw material charging method for alternately charging a massive iron oxide raw material and a massive carbonaceous material into a blast furnace in a layered manner, the raw material layer extending from an upper surface to a lower side of each raw material layer made of the massive iron oxide raw material. A method for charging a blast furnace raw material, characterized in that a carbon material-containing agglomerate containing iron oxide and carbon as main components is included in a portion having a thickness of 1/2 or less of the thickness. 2. The carbonaceous material-containing agglomerate is obtained by hot forming a mixture containing a powdery iron oxide-containing substance and a powdery carbonaceous material in a temperature range of 300 to 550 ° C. Item 1. A blast furnace raw material charging method according to Item 1. 3. The maximum fluidity (MF) of Giesera of the powdered carbonaceous material
Is log MF ≧ 1.0, The blast furnace raw material charging method according to claim 2. 4. The carbon amount in the carbonaceous material-containing agglomerate is 0.5 times or more of a theoretical carbon amount required to reduce iron oxide in the carbonaceous material-containing agglomerated ore. The blast furnace raw material charging method described in. 5. The detarring treatment is performed by holding the carbonaceous material-containing agglomerate at a temperature equal to or higher than the hot forming temperature for 5 minutes or more after the hot forming and before charging the blast furnace. 2-4
The blast furnace raw material charging method according to any one of 1. 6. The mass ratio of the massive iron oxide raw material and the total amount of the carbonaceous material-containing agglomerated ore and the massive carbonaceous material is 4 or more, according to claim 1. Blast furnace raw material charging method. 7. The blast furnace is characterized in that the amount of auxiliary fuel injected is pig iron.
The blast furnace raw material charging method according to any one of claims 1 to 6, wherein the blast furnace is 100 kg or more per ton.