KR102058834B1 - Method of charging raw material into blast furnace - Google Patents

Abstract

A method for charging raw materials into a blast furnace is proposed, which ensures air permeability in the blast furnace and achieves stabilization of the blast furnace operation and improvement in thermal efficiency. When charging the charging raw material which mixed the ore raw material and the coke through the turning chute into the blast furnace, the turning chute was inclined at an average angle θ1 with respect to the axial direction of the blast furnace to supply the charging raw material O1, and then the turning chute was Inclined by the average angle (theta) 2 larger than the said average angle (theta) 1, the charging raw material O2 which mixed coke with the particle diameter of 1.1-3.0 times the particle diameter of the coke mixed with the said charging raw material O1 is supplied, and a raw material loading layer is formed.

Description

Raw material charging method for blast furnace {METHOD OF CHARGING RAW MATERIAL INTO BLAST FURNACE}

This invention relates to the raw material charging method with respect to the blast furnace which charges a raw material through a turning chute in a blast furnace.

In the blast furnace, generally, ore raw materials such as sintered ores, pellets, ore ores and coke are stacked in the furnace direction from the top of the blast furnace, and the combustion gas flows from the blast furnace to burn the coke. It is a facility for obtaining pig iron from ore. The coke and ore raw materials, which are blast furnace charged raw materials charged in the blast furnace, are dropped from the top of the furnace to the bottom of the furnace, so that the reduction of the ore and the temperature rise of the raw materials occur. The ore raw material layer gradually deforms while filling the voids between the ore raw materials due to the temperature rise and the load from the upper side, and forms a fusion layer having a very high airflow resistance and hardly flowing gas under the shaft portion of the blast furnace. .

Conventionally, the charging of raw materials for blast furnaces involves charging ore raw materials and coke alternately, and in the furnace, the ore raw material layers and the coke layers are alternately layered. Moreover, in the lower part of a blast furnace, there exists an ore raw material layer with a large ventilation resistance which softened and fused ore, and a coke slit with a relatively small ventilation resistance derived from coke called a fusion band.

The air permeability of this fusion zone greatly affects the air permeability of the entire blast furnace, and speeds up the productivity in the blast furnace. When performing low coke operation which suppresses coke usage amount, since the amount of coke used is reduced, it is thought that coke slit becomes infinitely thin, and it is important to ensure the air permeability of a fusion | melting zone.

In order to improve the air permeability of a fusion | melting band, it is known that mixing coke to an ore raw material layer is effective. Therefore, much research has been made to obtain an appropriate mixing state of coke. For example, in Patent Literature 1, in a bellows blast furnace, coke is charged into an ore hopper downstream of the ore hopper, and the coke is stacked on an ore on a conveyor, and charged into a top bunker, thereby turning the chute chute. Ore and coke are charged into the blast furnace.

Moreover, in patent document 2, ore and coke are stored separately in the bunker of a top, and mixing and charging coke and ore simultaneously, three types of batches for coke normal charging, the center charging of coke, and the batch for mixing charging are provided. It is done at the same time.

Moreover, in patent document 3, in order to prevent destabilization of the fusion | melting zone shape in blast furnace operation, and the fall of the gas utilization rate in the vicinity of central part, and to plan safety operation and improvement of thermal efficiency, in the raw material charging method of blast furnace, In this case, the entire ore and the entire coke are completely mixed and charged into the furnace.

Japanese Patent Laid-Open No. 3-211210 Japanese Unexamined Patent Publication No. 2004-107794 Japanese Patent Publication No. 59-10402

By the way, in order to improve the air permeation resistance of a fusion | melting band, it is effective to mix coke in an ore layer like the technique of patent document 3 mentioned above.

However, since the average particle diameter of the representative coke of patent document 3 is about 40 mm, and the average particle diameter of ore is about 15 mm, and both particle sizes differ significantly, it is easy to mix ore in coke only by mixing it. Porosity may fall significantly, and air permeability may deteriorate in a furnace, and it may generate troubles, such as a blowout of gas and a fall fall of a raw material.

In order to avoid these troubles, a method of forming a layer of coke alone on the furnace core portion can be considered. According to this method, since the passage of the gas by the coke layer is secured to the furnace core part, the air permeability can be improved.

However, when operating a blast furnace reducing material in which pulverized coal is blown in from large quantities, air permeability is hindered by an increase in the amount of pulverized coal unburned and the Ore / Coke ratio (mass ratio of ore and coke). The air permeability of the surroundings is greatly deteriorated. Even if only the hearth section secures air permeability, the air permeability of the entire furnace is not sufficient. Moreover, when performing low coke operation as mentioned above, formation of the coke layer itself of a furnace core part may be insufficient.

The present invention was developed in view of the present situation, and even if the amount of coke is small or a large amount of coal injection operation of pulverized coal is carried out, the ventilation in the blast furnace is ensured, thereby achieving stabilization of the blast furnace operation and improvement of thermal efficiency. It is aimed to suggest about raw material charging method to blast furnace.

That is, the summary structure of this invention is as follows.

1.When charging the charging raw material which mixed the ore raw material and coke through a turning chute in a blast furnace,

Particle diameter of the coke which tilts the said turning chute | shoot with the average angle (theta) 1 with respect to the axial direction of the blast furnace, and then inclines the said turning chute with the average angle (theta) 2 larger than the said average angle (theta) 1, and mixes it with the said loading raw material O1. A raw material charging method for the blast furnace which supplies the charging raw material O2 which mixed coke which has a particle diameter of 1.1-3.0 times of to form the raw material charging layer.

Here, the ore raw material is a generic term for sintered ores, pellets, and bulk ores. In addition, the said average angle is defined by following Formula.

However, θk and i are angles with respect to the axial direction of the blast furnace of the i-th turning chute, and k = 1 represents θ1 and k = 2 represents θ2, respectively.

In addition, in said 1, although the formation of a raw material loading layer is prescribed | regulated, the lamination | stacking throughout the blast furnace performs the blast furnace operation by stacking a coke layer and a charging raw material layer alternately. Moreover, you may provide the coke layer extended in an axial direction in the blast furnace center part.

2. The raw material charging method for the blast furnace of 1 whose particle diameter of the coke mixed with the said loading raw material O2 is 1.5 times or more of the particle size of the coke mixed with the said loading raw material O1.

3. The raw material charging method with respect to the blast furnace of said 1 or 2 whose particle diameter of the coke mixed with the said loading raw material O1 is 0.5-1.5 times the particle diameter of the ore raw material mixed with the said charging raw material O1.

According to the present invention, even in the operation by low coke amount and the operation by mass injection of pulverized coal, the air permeability in the blast furnace can be secured reliably, so that stable blast furnace operation is realized under high thermal efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the blast furnace of a swing chute system.
It is a schematic diagram which shows the conventional raw material loading state.
It is a schematic diagram which shows the raw material loading state which concerns on this invention.

Hereinafter, the present invention will be described in detail.

An example in the case of applying the raw material charging method of the present invention to the blast furnace of the swing chute system of the actual machine will be described based on FIGS. 1 to 3.

In Fig. 1, reference numeral 1 denotes a blast furnace, 2 a blast furnace furnace section, 3 a blast furnace furnace section, 4a to 4c a top bunker, 5 a coke layer, 5a a center coke layer, and 5b a Peripheral coke layer, 6 is a raw material layer mixed with ore raw material and coke, 7 is an assembly hopper, 8 is a bellless charging device, 9 is a chute chute, and 10 is a blower tube.

In this example, only the coke is stored in the top bunkers 4a and 4b, and only the ore raw material is stored in the top bunker 4c, respectively. Moreover, the coke in which particle size differs is stored in 4a and 4b which charged only coke. And it simultaneously supplies out from the top bunkers 4a and 4c, and simultaneously sends out from the top bunkers 4b and 4c, and supplies the mixed ore raw material and coke. In addition, the method of forming the mixed layer from which a coke particle diameter differs is not limited to the above, For example, on the conveyor which conveys a raw material etc. to a top bunker, what mixed the ore raw material and coke in advance is conveyed to a top bunker, You may supply this mixture from one top bunker.

Charging of the raw material in the blast furnace of the swing chute system is performed by charging the charging raw material and the coke alternately by the swing chute 9, and the coke layer 5 and the charging raw material layer 6 alternately in the furnace. Deposited in layers.

Here, as an example of the charging procedure of a specific coke layer, as shown in FIG. 2 by the so-called order tilt system, first, the raw material loading destination of the turning chute 9 is made into the furnace wall inner peripheral part of the blast furnace 1. Then, by charging the coke from the top bunker 4a or 4b in which only the coke is charged, the peripheral coke layer 5b is formed in the inner wall of the furnace wall. Subsequently, the coke is charged from the top bunker 4a or 4b using the raw material charging destination of the turning chute 9 as the shaft center portion of the blast furnace, thereby forming the center coke layer 5a at the shaft center portion of the blast furnace.

The charging raw material layer 6 is piled up and formed on the coke layer 5 formed in this way. Previously, as shown in this FIG. 2, the single charging raw material layer 6 was formed.

On the other hand, in this invention, as shown in FIG. 3, the charging raw material O1 which mixed by sending out the ore raw material raw material from the top bunker 4c and the coke of the small particle size from the top bunker 4a simultaneously is made into the core ( It is supplied to the core side, and the inner loading raw material layer 6a is formed. Furthermore, the charging raw material O2 mixed with the coke of the large particle diameter than the coke of the charging raw material O1 from the top bunker 4c and the charging raw material O1 from the top bunker 4b simultaneously was supplied to the furnace wall side, and the outer charging raw material layer ( 6b). The charging raw material layer 6 is comprised by lamination | stacking these inner charging raw material layers 6a and outer charging raw material layers 6b. In that case, it is important to make ratio (DpC2 / DpC1) of the particle size (DpC2) of the coke mixed with the said loading raw material O2, and the particle size (DpC1) of the coke mixed with the loading raw material O1 to 1.1-3.0.

That is, as shown in FIG. 1, when setting the angle with respect to the axis L of the blast furnace of the turning chute 9 as (theta), first, tilting the turning chute 9 by the average angle (theta) 1, and charging raw material O1 to the core side It supplies and forms the inner charging raw material layer 6a. Next, the turning chute 9 is inclined at an average angle θ2 greater than the average angle θ1, and the charging raw material O2 having a large particle size of the mixed coke is supplied to form the outer charging raw material layer 6b.

Here, it is preferable that the said average angles (theta) 1 and (theta) 2 of the turning chute 9 make (theta) 2 / (theta) 1 to 1.1-2.0 from a viewpoint of ensuring the air permeability and reactivity of the charging raw material layer.

By stacking the charged raw material layer 6 laminated as described above alternately with the coke layer 5, the ventilation in a blast furnace can be ensured reliably. This is because the gas flow velocity in the blast furnace is not uniformly distributed from the center of the furnace to the furnace wall, so that air permeability can be secured by charging coke having a different particle diameter. That is, since the furnace wall part in the shortest path | route which connects the blast furnace groove and the furnace port is easy to flow, the coke of breathable large particle size is charged so that the gas flow may not be impaired.

In particular, by setting the ratio (DpC2 / DpC1) of the particle size (DpC2) of the coke mixed with the charging raw material O2 and the particle size (DpC2 / DpC1) of the coke mixed with the charging raw material O1 to 1.1 to 3.0, the charging raw material O1 disposed on the core side In order to secure the reducibility of the ore, coke having a small particle size with high reactivity is deposited and mixed, and coke having a large particle size with a small air resistance is deposited and mixed in the charging material O2 to improve breathability. Breathability can be achieved at a high level.

That is, when ratio (DpC2 / DpC1) is less than 1.1, since the coke with large particle size with small airflow resistance cannot be deposited and mixed, the improvement effect of air permeability is not acquired. Preferably it is 1.5 or more. On the other hand, when the ratio (DpC2 / DpC1) exceeds 3.0, the air permeation resistance is small, but since the reactivity is further lowered, the effect of improving the reducibility is not obtained. Preferably it is 2.0 or less.

Moreover, it is preferable that ratio (DpC1 / DpO1) of the particle size (DpC1) of coke mixed with charging raw material O1 with respect to the particle size (DpO1) of the ore raw material mixed with charging raw material O1 is 0.5-1.5.

In other words, if the ratio DpC1 / DpO1 is less than 0.5, coke of a small particle size is mixed near the furnace center to increase the ventilation resistance and inhibit the gas flow flowing near the center of the blast furnace. On the other hand, when ratio (DpC1 / DpO1) exceeds 1.5, it is because the reactivity in the charging raw material O1 arrange | positioned at the core side becomes small, and it becomes difficult to acquire the improvement effect of reducibility. More preferably, it is 1.0-1.2.

Example

In the blast furnace actual machine of the swing chute system shown in FIG. 1, after making the coke mixing ratio mixed with the ore raw material at the same tapping ratio, DpC2 / DpC1 in the charging raw materials O1 and O2, the charging raw material O1 Each operation which prepares loading raw materials O1 and O2 which varied DpC1 / DpO1 in Equation 1 as shown in Table 1, sets them as the average angles θ1 and θ2 of the turning chute shown in Table 1, and loads them in the blast furnace It was. The operation results in each case were examined. The findings are written together in Table 1.

Here, the tapping ratio is a value obtained by dividing the tapping amount (t / d) per day of the blast furnace by the furnace volume (m 3). In addition, the reducing material ratio, coke ratio, and pulverized coal ratio are the reducing material amount, coke amount, and pulverized coal amount (kg / t) which were used when manufacturing molten iron 1 t.

As shown in Table 1, inventive examples 1-9 are the range of 339-353 kg / t of cokes ratio, and become a low cokes ratio compared with the cokes ratio 356-360 kg / t of comparative examples 1-3. However, even in such low coke ratio operation, (DELTA) P / V which is an index of ventilation resistance could be suppressed in the range of 18.3-20.8 which is lower than the range of 20.9-23.1 in Comparative Examples 1-3.

1: blast furnace
2: blast furnace
3: blast furnace old man
4a to 4c: top bunker
5: coke layer
5a: center coke layer
5b: surrounding coke layer
6: charging raw material layer
6a: inner charging raw material layer
6b: outer charging raw material layer
7: set hopper
8: bellless charging device
9: turning suit
10: blower

Claims (3)

When charging the charging raw material which mixed the ore raw material and coke through the turning chute in a blast furnace,
The turning chute is tilted at an average angle θ1 with respect to the axial direction of the blast furnace to supply the charging raw material O1 in which coke having a particle size of 0.5 to 1.2 times the particle diameter of the ore raw material and the ore raw material is mixed, and then the turning chute. The coke having a particle size of 1.1 to 2.0 times the particle size of the same ore raw material as the ore raw material mixed with the charged raw material O1 and the coke mixed with the charged raw material O1 is inclined at an average angle θ2 greater than the average angle θ1. A raw material charging method for the blast furnace which supplies the charging raw material O2 mixed and forms a raw material charging layer. The method of claim 1,
The particle size of the coke mixed with the said loading raw material O2 is a raw material charging method with respect to the blast furnace which is 1.5 times or more of the particle size of the coke mixed with the said loading raw material O1. delete

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