JPH11117007A - Operation of blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the stagnation of reduction at the center part of a blast furnace and to execute the stable operation with low fuel consumption, even in the case that the blending ratio of pellets is high in the blast furnace charging materials composed of sintered ore and the pellets. SOLUTION: The increasing effect of the blending ratio of the sintered ore is not simply increased according to the increase, but the property of the pellets is singly and firstly changed at the time of becoming >=70 wt.%. Therefore, since the stagnation of the reduction at the center part and the peripheral part of the blast furnace can efficiently be prevented even with the low fuel consumption by charging the blast furnace charging materials containing >=70 wt.% sintered ore and the balance pellets into the center part of the blast furnace where the reducing condition is not good, and charging the blast furnace charging materials containing >=70 wt.% pellets and the balance sintered ore into the peripheral part where the reducing condition is good, the stable operation of the blast furnace can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a blast furnace operating method for charging a blast furnace charge into a blast furnace with a bellless type charging apparatus, and more particularly to a blast furnace operating with a blast furnace charge containing a large amount of pellets. Belongs to the technical field of blast furnace operation method most suitable for maintaining stable operation of blast furnace.

[0002]

2. Description of the Related Art As is well known, the physical and chemical properties of pellets and sinter charged in a blast furnace are different. First, the pellets have a smaller angle of repose than the sintered ore because of their round shape, and when charged from the top of the blast furnace, they flow into the center of the furnace and deteriorate the permeability of the center of the blast furnace. There is a tendency for unstable peripheral flows. Second, since the porosity of the pellet is smaller than that of the sintered ore, if the reduction potential is low, the reduction stagnation tends to occur, and the high-temperature property tends to deteriorate.

[0003] Therefore, in the blast furnace operation by charging the pellets, if the charging amount of the pellets increases, a ventilation obstacle occurs,
Since the gas flow distribution in the blast furnace becomes unstable, stable operation of the blast furnace becomes difficult. Generally, in order to maintain the stable operation of the blast furnace and to protect the furnace body of the blast furnace, it is extremely important to keep the gas flow in the blast furnace at a central flow.

[0004] More specifically, when the gas flow distribution becomes unstable, there may be places in the radial direction of the blast furnace where it is impossible to secure a gas amount necessary for reducing the blast furnace charge. When the blast furnace charge that has passed such a gas-deficient location falls to the lower part of the blast furnace, a ventilation obstacle due to fusion of the unreduced melt occurs,
Induction of furnace condition and furnace heat decrease due to shelf hanging and slipping. At the same time, the gas flow tends to be a peripheral flow, and high-temperature gas containing zinc and alkali rises along the inner wall of the furnace, causing damage to furnace body cooling equipment such as furnace bricks and staves. Trigger. In order to avoid such a problem, various charging methods of a blast furnace charge have been conventionally proposed.

For example, JP-A-58-157905 or JP-B-3-14883 consider that it is desirable to distribute the pellets uniformly in the radial direction of the blast furnace.
It is disclosed that pellets and other ores are uniformly mixed in advance on a conveyor belt or in a raw material deposition hopper and then uniformly charged into a blast furnace. (Conventional example 1)

Further, Japanese Patent Application Laid-Open No. 2-254112 or Japanese Patent Publication No. 57-45288 discloses that a carbonaceous material or a highly reactive coke (for example, small-grain coke, etc.) ) Is disclosed. (Conventional example 2)

Further, Japanese Patent Publication No. 2-51962 or Japanese Patent Publication No. 59-10404 discloses that in order to stabilize the gas flow distribution, coke is supplied to a blast furnace by a bell armor type or bellless type charging device. On the basis of charging the ore into the peripheral side at the center in the radial direction, the layer thickness ratio O / C of the ore layer and the coke layer in the radial direction of the blast furnace is surely adjusted, so that the blast furnace is It is disclosed that a proper gas flow is generated at the center. (Conventional example 3)

[0008]

In the case of a blast furnace operation in which a blast furnace charge consisting of sinter ore and pellets containing a large amount of pellets is charged, as described above, the disadvantages of the pellets are compensated for and the gas flow is reduced. In order to stabilize the distribution, it is basically to mix the pellets and the sintered ore uniformly, charge them with a charging device, and adjust the layer thickness ratio O / C between the ore layer and the coke layer. Has become. In the actual blast furnace operation, FIG. 7 is an explanatory diagram showing the relationship between the pellet blending ratio (%) and the fuel ratio (kg / t).
As shown in the figure, even if there is some fluctuation in the gas flow distribution, stable operation is considered first, and although the cost increases, the fuel ratio is increased in advance so as not to adversely affect the ore reduction, and the blast furnace The overall air permeability and reduction potential are increased. By the way, in order to aim for low cost and high productivity, reduction of coke ratio and fuel ratio is an essential requirement.
Therefore, in the method of charging the blast furnace charge and the gas flow distribution control according to the conventional example described above, there is a limit to the reduction of the fuel ratio as shown in the actual operation results, and the objective of lower cost and high productivity is achieved. Cannot be achieved. Further, if highly reactive coke is mixed in the pellet layer, the amount of coke as a coke slit must be reduced, and thus the amount of highly reactive coke mixed is also limited.

Therefore, an object of the present invention is to ensure the permeability and reduction potential of the entire blast furnace even if the blending ratio of the pellets of the blast furnace charge composed of the sintered ore and the pellets is high, Moreover, it is an object of the present invention to provide a blast furnace operating method which enables stable operation with a low fuel ratio.

[0010]

Means for Solving the Problems The present inventors pay attention to the difference in each reduction condition in the radial direction of the blast furnace and the properties of the blast furnace charge, and distribute the blast furnace charge appropriate for each reduction condition. I thought about charging. And, since the basic gas flow must be maintained as the central flow, the reduction stagnation does not occur for each radial reduction condition of the blast furnace when the gas flow distribution is maintained as the central flow. The present invention has been made by clarifying the mixing ratio of the pellets and the sintered ore.

Therefore, in order to solve the above-mentioned problems, the gist of the means adopted by the blast furnace operating method according to claim 1 of the present invention is that the sintered ore and the pellets are charged into the blast furnace by a bellless type charging device. In the blast furnace operating method in which a sinter containing pellets of 30 Wt% or more and pellets and pellets are formed on the coke terrace in the blast furnace and the gas flow is a central flow, 70 Wt% or more is used. The blast furnace charge A consisting of the sintered ore and the remaining pellets is replaced with a blast furnace radius R of 0.6R.
And a blast furnace charge B composed of pellets of 70 Wt% or more and residual sinter is charged into the outer peripheral portion of the blast furnace charge A charged in the blast furnace. It is characterized by doing.

In order to solve the above problems, the gist of the means adopted by the blast furnace operating method according to the second aspect of the present invention is that a sinter ore and pellets are charged into a blast furnace by a bellless type charging device. In the blast furnace operating method in which a sinter containing pellets of 30 Wt% or more and pellets in the blast furnace and pellets are formed on the coke terrace, and the blast furnace operation method in which the gas flow is a central flow, 70 Wt% or more is used. The blast furnace charge A consisting of the sintered ore and the remaining pellets is replaced with a blast furnace radius R of 0.6R.
After the coke terrace is charged into the center within the range of the above and the coke terrace is not broken with the pellets to be charged next, only the pellets are coke terraces on the outer peripheral portion of the blast furnace charge A charged into the blast furnace. A pellet ore is charged on the pellet terrace, and a sintered ore is charged on the pellet terrace. A layer of the blast furnace charge B consisting of

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1 according to a blast furnace operating method of the present invention using a blast furnace equipped with a bellless type charging device will be described below with reference to FIG.
FIG. 2 is an explanatory diagram of the temperature distribution in the blast furnace when the gas flow is maintained at the central flow, FIG. 3 is an explanatory diagram of the heating pattern and the gas composition pattern, and the reduction rate and shrinkage of the sinter under the conditions shown in FIG. FIG. 4 showing the relationship between the reduction ratio and the shrinkage ratio of the pellet under the conditions shown in FIG. 3 and FIG. 6 showing the relationship between the compounding ratio of the sinter and the pressure drop rapid rise temperature. And FIG. 9 showing the relationship between the blending ratio of the pellets and the fuel ratio.

1, 4 and 5 show the contraction rate and the reduction rate on the left vertical axis, the pressure loss on the right vertical axis, and the temperature on the horizontal axis, respectively. FIG. 3 shows temperature on the vertical axis and time (minutes) on the horizontal axis, and FIG. 6 shows pressure drop rapid rise temperature on the vertical axis and the sinter mixing ratio on the horizontal axis. FIG. 9 shows the fuel ratio on the vertical axis and the pellet blending ratio on the horizontal axis.

In general, the desired high temperature properties of the blast furnace charge,
That is, the temperature-shrinkage rate, the temperature-reduction rate, and the temperature-pressure loss are indicated by broken lines (solid lines indicate a normal state) in FIG. It is considered that a material having a narrow cohesive zone in a so-called blast furnace having a small pressure drop level and a low pressure loss level is good. In order to bring the high-temperature properties of the blast furnace charge close to such high-temperature properties, the contents of calcium oxide, silicon dioxide, magnesium oxide, etc. may be changed to modify the blast furnace charge. If it is difficult to change, etc., devise the method of use, for example, mix ore and high-reaction coke into the blast furnace and change the reduction conditions (increase the reduction potential)
However, it is necessary to prevent the fusion between the pellet particles, but this is not preferable from the viewpoint of narrowing the coke slit width.

As shown in FIG. 2, the temperature distribution in the blast furnace when the gas flow is maintained at the central flow has a steep temperature gradient in the center of the blast furnace and a relatively high temperature gradient in the peripheral part. It has become moderate. Therefore, in order to confirm the influence of the different temperature gradient between the central portion and the peripheral portion of the blast furnace on the charge in the blast furnace, the reduction conditions in the blast furnace (the central portion, the intermediate portion, and the central portion near the center of the blast furnace) were used. The relationship between the temperature and gas composition in the surrounding area) and the high-temperature properties of the blast furnace charge (sinter ore, pellets) were investigated.

First, the conditions for reducing the blast furnace charge are as follows.
With reference to the actually measured temperature distribution in the blast furnace, the radial direction of the blast furnace when the inner diameter of the blast furnace is R, the center of the range of 0 to less than 0.6 R, and 0.6R to less than 0.8 R The zone is divided into three zones: a middle portion of the range and a peripheral portion in the range of 0.8R to 1.0R, and the heating pattern and the gas composition pattern in each zone are shown in FIG. In both cases, the center is a solid line, the middle is a dashed line,
The peripheral portions are indicated by dotted lines. ). Under such conditions, the reduction ratio (%), shrinkage ratio (%), and pressure loss (mmH ₂₎
O) is as shown in FIG. 4, and the reduction ratio (%), shrinkage ratio (%) and pressure loss (mmH ₂ O) of the pellet are as shown in FIG. In FIGS. 4 and 5, as in FIG. 3, the center is indicated by a solid line, the middle is indicated by a broken line, and the periphery is indicated by a dotted line.

In the sinter, as shown in FIG. 4, even if the respective temperature conditions from the central portion to the peripheral portion of the blast furnace are changed, there is no significant effect on the high-temperature properties. However, in the pellets, as shown in FIG. 5, the high-temperature properties deteriorated with an increase in the heating rate, and the high-temperature properties particularly deteriorated at the center of the blast furnace, indicating that reduction stagnation occurred. Have been

As a means for alleviating the reduction stagnation in the central part of the blast furnace, for example, it is conceivable to charge the central part of the blast furnace with a blast furnace charge in which a sintered ore and a pellet are mixed. Therefore, the relationship between the mixing ratio of the sintered ore and the high-temperature properties of the blast furnace charge in which the sintered ore and the pellet were mixed was examined. The investigation results are as shown in FIG.

According to FIG. 6, the effect of increasing the compounding ratio of the sintered ore does not increase monotonically with the increase in the compounding ratio, but the compounding ratio of the sintered ore becomes 70 Wt% or more. It is only after that that the properties of the pellet alone change. From these results, when charging the blast furnace charge consisting of sintered ore and pellets in the blast furnace, the range in which the heating conditions at the center of the blast furnace are high and the reduction conditions for the pellets are relatively poor, that is, 70Wt in the range of 0 to 0.6R in the radial direction of the blast furnace
% Of the blast furnace charge A, which is composed of sinter ore and pellets in which sinter ore of not less than% is blended.

Therefore, by charging the blast furnace charge A having the above mixing ratio into the blast furnace, reduction stagnation caused by pellets in a range where the reduction conditions in the center of the blast furnace are relatively poor is prevented. be able to. Of course, in a range where the reduction conditions in the peripheral portion are good, although the pellet blending ratio of the blast furnace charge B is as high as 70 Wt%, there is no possibility that reduction stagnation due to the pellets occurs. Note that, as is well understood from FIG. 5, the reducibility is 0 even in the middle part of the blast furnace in the range of 0.6R to less than 0.8R.
There is no significant difference from the central part in the range of less than ~ 0.6R. However, at least in the range of 0 to 0.6R, 70Wt
% Of sinter ore and pellets containing sinter ore containing at least 30 wt% of sinter ore.
The above pellets are blended to enable stable blast furnace operation.

Incidentally, in the blast furnace operating method according to the first embodiment, the blending ratio of the pellets of the blast furnace charge is about 56 W.
t%. In this way, when the blast furnace charge mixed with the 56 Wt% pellets is charged and the blast furnace is operated by the conventional method, the fuel ratio becomes 500 to 52 as shown in FIG.
Although it is 0 kg / t, the blast furnace operating method according to this embodiment can prevent the adverse effect of the pellets, and has the same effect as in the all-sintering operation, that is, the fuel ratio is 4%.
At 90 kg / t, a reduction effect of about 4% can be expected as compared with the conventional method.

Therefore, it is possible to increase the permeability and the reduction potential of the entire blast furnace at a lower fuel ratio than before, without increasing the fuel ratio and increasing the permeability and the reduction potential of the entire blast furnace as in the prior art. Therefore, stable operation can be performed. When charging the blast furnace charge in the hopper provided at the top of the blast furnace into the radial center of the blast furnace using a bellless charging device, the swirling chute should be continuously applied within a steeper inclination angle range. When the swing chute is turned and the peripheral chute is charged, the swing chute is continuously turned in a gentler inclination angle range.

Next, the method for operating the blast furnace according to the second embodiment of the present invention will be described with reference to FIG. 7 which is an explanatory diagram of the distribution of pellets in the radial direction of the blast furnace of the blast furnace charge composed of sintered ore and pellets of 50 wt% each. A description will be given with reference to FIG. 8 showing the O / C distribution in the radial direction of the blast furnace and the pellet distribution when the blast furnace charge containing a large amount of pellets is charged into the furnace wall side of the blast furnace.

By the way, when pellets and sintered ore are mixed in advance and charged into a blast furnace as in the blast furnace operating method according to the conventional example, FIG. 7 (each mark shows a difference in charging conditions. The circles indicate the cases where the O / C on the wall side of the blast furnace was reduced by changing the tilt angle and the number of turns of the swirling chute, and the triangles indicate the O / C on the wall side.
And the square marks indicate the case where the O / C on the wall side is intermediate between the two. ),
Even if the falling position of the charge in the blast furnace is changed by changing the tilt angle and the number of turns of the swirling chute, the distribution becomes almost uniform from the radial center of the blast furnace to the inner wall, and the pellet distribution in the radial direction of the blast furnace is changed. Can not do. Also, the blast furnace charge containing the pellets falls into the blast furnace, and a separation phenomenon occurs when flowing into the center of the blast furnace along the slope of the charge layer,
Pellets with a small angle of repose are relatively large on the center side of the blast furnace, and conversely, sinter is large on the peripheral side.

Therefore, in order to obtain the target charge distribution and to operate the blast furnace at a low fuel ratio,
Rather than mixing the pellets and the sinter in advance and charging the blast furnace, the pellets and the sinter are separated separately.At the center side of the blast furnace, the sinter whose high-temperature properties are not easily affected by the reducing conditions is used. It is considered that the method of charging and charging the pellets on the peripheral side is effective.

Therefore, a blast furnace charge A consisting of sintered ore of 70 Wt% or more and residual pellets is charged at the center of the blast furnace and within a range of 0.6R of the blast furnace radius R, and then charged. After the coke terrace is not broken with the pellets to be crushed, only the pellets are charged on the coke terrace in the range outside the blast furnace charge A charged into the blast furnace, and the sinter is placed on the pellet terrace. Was adjusted to adjust the O / C to a predetermined ratio.

The result is as shown in FIG.
The distribution of O / C indicated by the solid line in the radial direction of the blast furnace is substantially within the range of the target value indicated by oblique lines, and the pellet distribution of the blast furnace charge in the radial direction of the blast furnace is 20 W in the range of 0.6R.
% Or less, that is, 70 Wt% or more. Therefore, according to the blast furnace operating method according to the second embodiment, the sinter distribution in the range of 0.6R in the radial direction of the blast furnace is 70 Wt% or more.
Is the same as

[0029]

As described in detail above, claim 1 of the present invention
According to the blast furnace operating method according to (2), 70 Wt% is in a range where the reduction condition of the blast furnace charge in the center of the blast furnace is relatively poor, that is, in a range of 0 to less than 0.6 R in the radial direction of the blast furnace.
A blast furnace charge composed of the sintered ore and the pellets containing the above-mentioned sinter was charged, and the blast furnace charged with the pellets of 70 Wt% or more in a range where the reduction conditions of the blast furnace charge in the peripheral portion were good. Since the blast furnace charge consisting of condensed matter and pellets is charged, reduction stagnation caused by pellets is prevented without increasing the fuel ratio as in the past, increasing the permeability and reduction potential of the entire blast furnace. Thus, there is an extremely excellent effect that stable operation can be performed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of desirable high-temperature properties of a blast furnace charge according to the first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a temperature distribution in a blast furnace when a gas flow is maintained at a central flow according to the first embodiment of the present invention.

FIG. 3 is an explanatory view of a heating pattern and a gas composition pattern according to the first embodiment of the present invention.

4 is an explanatory diagram of a reduction ratio, a shrinkage ratio, and a pressure loss of a sintered ore under the conditions shown in FIG.

5 is an explanatory diagram of a reduction rate, a shrinkage rate, and a pressure loss of a pellet under the conditions shown in FIG.

FIG. 6 is a diagram illustrating the relationship between the mixing ratio of sintered ore and high-temperature properties (pressure drop rapid rise temperature) according to Embodiment 1 of the present invention.

FIG. 7 is an explanatory diagram of a pellet distribution in a radial direction of a blast furnace of a blast furnace charge composed of sintered ore and pellets of 50 Wt% each.

FIG. 8 is an explanatory diagram of O / C distribution and pellet distribution in the radial direction of a blast furnace when a blast furnace charge containing a large amount of pellets is charged on the furnace wall side of the blast furnace according to the second embodiment of the present invention. is there.

FIG. 9 is a diagram illustrating the relationship between a blending ratio (%) of a pellet and a fuel ratio (kg / t) according to a conventional example.

Claims (2)

[Claims] 1. A sinter ore and pellets are charged into a blast furnace by a bell-less charging device, and a charge layer composed of sinter and pellets containing 30 Wt% or more pellets is coke in the blast furnace. In the blast furnace operating method in which a gas flow is formed as a central flow while being formed on a terrace, a blast furnace charge A comprising 70 Wt% or more of sintered ore and remaining pellets is subjected to a blast furnace radius R.
At the center within the range of 0.6R and 70W
Blast furnace charge B consisting of pellets of at least t% and residual sinter
Blast furnace is charged into the outer peripheral portion of the blast furnace charge A charged into the blast furnace. 2. A sinter ore and pellets are charged into a blast furnace by a bell-less charging device, and a charge layer comprising sinter and pellets containing 30 Wt% or more pellets is coke in the blast furnace. In the blast furnace operating method in which a gas flow is formed as a central flow while being formed on a terrace, a blast furnace charge A comprising 70 Wt% or more of sintered ore and remaining pellets is subjected to a blast furnace radius R.
Of the blast furnace charge A in which only the pellets were charged into the blast furnace after charging the coke terrace with the pellets charged in the center within the range of 0.6R. To form a pellet terrace, and charge sinter ore on the pellet terrace to form 70 Wt% on the outer periphery of the blast furnace charge A.
A method for operating a blast furnace, comprising forming a layer of the blast furnace charge B comprising the above pellets and residual sinter.