JPS5910401B2 - Blast furnace raw material charging method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for charging raw material into a blast furnace, and in particular, to a method for charging raw material into a blast furnace, particularly for ores containing relatively large amounts of sintered ore and lump ore as iron raw materials. This article relates to raw material charging methods for obtaining distribution and stable operation.

Normally, in blast furnace operation, ores such as pellets, sintered ore, ore lumps, and coke as a heat source and reducing agent are charged in a layer at a predetermined ratio, and this charge is brought into contact with gas in the furnace. This is carried out by lowering the mixture downward while heating and reducing the reaction.

In this case, in order to stabilize the furnace condition and protect the furnace wall members, it is necessary to increase the rate of rise (flow velocity) of the gas in the furnace at the center of the furnace than at the furnace wall side, thereby raising the temperature at the center of the furnace. is considered desirable.

However, if the gas flow rate in the furnace center becomes too high and the gas flow rate in the furnace wall becomes too low, the heating and reduction reaction of the charge in that area will become too slow, which will actually impede smooth operation. Therefore, it is necessary to adjust the gas flow rate in the furnace within an appropriate range and to take measures according to the properties of the charged material so that a preferable temperature distribution can be maintained.

Incidentally, in recent years, there has been a wide variety of types of ores due to raw material conditions, and lump ores, pellet sintered ores, etc. are charged singly or in combination in appropriate proportions.

The physical properties of these ores are different; for example, pellets have a spherical shape, whereas sintered ores, lump ores, etc. have angular, irregular shapes.

For this reason, when charged into the furnace from the furnace top furnace port, the state of deposition differs depending on its properties, and sintered ore and lump ore exhibit a significantly larger rest angle than pellets.

Therefore, when charging sintered ore or lump ore alone as iron raw materials, or even when charging in combination with pellets, if the mixing ratio is high, the layer of charged ores will be The angle of inclination inside the furnace increases.

As a result, near the furnace wall, the ore layer is thick and the coke layer is relatively thin, while in the furnace center, the ore layer thickness decreases and the coke layer thickness increases. .

However, the ventilation resistance (pressure loss) of ores is much higher than that of coke, so under the above charging conditions, the ventilation resistance at the center of the furnace decreases and the rising gas flow rate increases excessively. As a result, the ventilation resistance on the furnace wall side increases and the upward flow of gas in that area is significantly obstructed, which disturbs the preferred gas flow rate distribution, making it impossible to maintain stable furnace conditions, resulting in decreased operational performance and serious problems. Problems such as troubles may occur.

Therefore, in situations where a large amount of sintered ore or lump ore is used as a raw material, it is necessary to provide a deposition condition in the furnace according to the properties of the ore so that the gas flow at the furnace wall is not excessively obstructed. is necessary.

The present invention was made in order to solve the above-mentioned problems, and it was found that the inclination angle of the coke layer could be changed by devising the coke charging operation, and the inclination angle of the coke layer was This work was completed after discovering that the thickness of the ore layer in the radial direction within the furnace can be indirectly adjusted by changing the thickness of the ore layer.

That is, in the present invention, when charging coke and ores containing sintered ore and lump ore into a blast furnace at a predetermined ratio in layers, the amount of coke charged per charge is divided into two,
The second charge amount is (average layer thickness of coke (mW)
) / furnace mouth radius (7ffW)) is adjusted to be approximately 0.10 or less, thereby increasing the inclination angle of the coke layer in the furnace, thereby increasing the coke layer thickness on the furnace wall. The present invention provides a method for charging raw materials into a blast furnace, which increases the thickness of the ore layer and relatively reduces the thickness of the ore layer.

Figure 1 [1] is a diagram schematically showing the general layered deposition state of ores and coke in a blast furnace, where C is the coke layer, O is the ore layer, and θC and θ0 are respectively The angle of inclination of the coke layer and ore layer is shown.

The inclination angle θC of the coke layer is unrelated to the inclination angle θ0 of the underlying ore layer and is always approximately 0. ”It is 31.7°.

On the other hand, the inclination angle θ0 of the ore layer O varies depending on the blending ratio of sintered ore and lump ore in the ore layer and the amount of ore charged.

FIG. 2 shows measurement results regarding the effects of the blending ratio and charging amount of sintered ore on the inclination angle θ0 of the ore layer.

The charging amount (horizontal axis) is the average layer thickness (mal) of the ore layer.
/ furnace mouth radius (71l11L).

In the figure, curve 1 represents the case where the blending ratio of sintered ore and lump ore in the charged ore is 100% (weight, same hereinafter), curve 2 represents 80%, and curve 3 represents 60%.

As shown in the figure, the higher the blending ratio, the larger the inclination angle θ0 of the ore layer.

The fact that this inclination angle θ0 becomes larger is shown in FIG.
], the thickness to of the ore layer on the furnace wall side increases, and therefore the ventilation resistance of the furnace wall increases.

Furthermore, as mentioned above, since the inclination angle θC of the coke layer is always constant, as the ore layer thickness increases on the furnace wall side, the thickness of the coke layer inevitably decreases on the furnace wall side, and on the furnace center side. increases with

This change in coke layer thickness increases the gas flow rate at the furnace center, while decreasing the gas flow rate at the furnace wall.

Due to such changes in the thickness of each layer, the ventilation resistance of the contents in the furnace is greatly reduced at the center of the furnace and significantly increased at the walls of the furnace.

As a result, the rise of the gas flow in the furnace at the furnace wall is extremely inhibited, and the heating and reduction reactions in this area are greatly delayed.
The furnace condition will become unstable.

Furthermore, according to the figure, it is shown that the inclination angle of the ore layer can be adjusted to some extent by changing the amount of ore charged.
Since the charging amount of ores itself cannot be changed arbitrarily, it is practically difficult to utilize this as a control factor.

In order to cope with this, in the present invention, the thickness 1c of the coke layer on the furnace wall side is increased by increasing the inclination angle θC of the coke layer C, thereby reducing the ore layer to.

As a means of increasing the inclination angle θC of the coke layer, the amount of coke charged for one charge is divided into two parts, and each part is charged separately.

FIG. 1 [■■] is a diagram schematically showing the state of accumulation of charges when charging is carried out in such a manner.

C1 and C2 are the coke layers charged in the first and second times, respectively, and the two layers together make up the amount of coke for one charge.

θc1 and θc2 represent the inclination angle of each coke layer.

FIG. 3 shows the results of measuring changes in the inclination angle of each coke layer when such split charging was performed.

The horizontal axis of the figure shows the amount of coke charged for the second time as a ratio of (average thickness of coke layer (mm)/radius of furnace mouth (7X71!)).

In the figure, 1 is the inclination angle θc of the first charged coke layer C1.
1 and 2 are the inclination angle θc2 of the second charged coke layer C2
shows the change in

According to the figure, the inclination angle θc1 of the coke layer C1 is:
It always exhibits a fairly constant value (approximately 31.7°) regardless of the charging amount or the inclination angle θ0 of the underlying ore layer 0, whereas the second coke layer formed on top of this coke layer C1 The inclination angle θC2 of the charged coke C2 tends to increase as the amount of charged coke decreases in a range where the ratio of the average layer thickness of the coke layer/the radius of the furnace mouth is about 0.10 or less.

The inclination angle θe2 of this second layer is the same as that of the first and second layers.
It represents the inclination angle of the coke layer for one charge, which is the sum of the respective layers (C1 and 02).

In other words, the inclination angle of the coke layer formed by the charging amount per charge is determined by the second charging amount in two-time split charging, and the second charging amount is determined by the average layer thickness of coke. It is possible to increase the ratio by adjusting the ratio of (shape)/furnace radius (shape) to approximately 0.10 or less.

As the inclination angle of the coke layer increases, the thickness of the coke layer inevitably becomes thicker on the furnace wall side and thinner on the furnace center.

At this time, since the inclination angle of the ore layer remains unchanged at X, the layer thickness decreases on the y wall side and increases at the center of the furnace.

As a result, the ventilation resistance of the furnace gas decreases at the furnace wall and increases at the furnace center. As the temperature rises, the heating and reduction reactions of the ores are promoted, and stable furnace conditions are maintained.

As described above, according to the present invention, it is possible to give the coke layer in the furnace a desired inclination angle by dividing the amount of coke charged into two parts and adjusting the second amount of charging. can.

Thereby, the thickness of the ore layer and the coke layer in the furnace can be adjusted in the radial direction of the furnace mouth, and the ventilation resistance in the furnace can be maintained in a desired state.

In particular, when sintered ore or lump ore is used extensively as ores, this causes an abnormal increase in ventilation resistance at the furnace wall and the accompanying instability of the furnace condition. By reducing the amount of coke charged for the second time and increasing the angle of inclination of the coke layer, abnormal deviation in ventilation resistance can be alleviated, and highly efficient blast furnace operation can be performed under stable furnace conditions.

[Brief explanation of the drawing]

Figures 1 (CI) and (II) are explanatory diagrams showing the state of layered deposition of the contents in the blast furnace, Figure 2 is a graph showing the influence of the blending ratio and charging amount of ores on the inclination angle of ores, FIG. 3 is a graph showing the influence of the amount of coke charged in the second time on the inclination angle of the coke layer. O...Ore layer, C...Coke layer, θ0...
Inclination angle of ore layer, θC... inclination angle of coke layer, to... layer thickness of ore, tc... layer thickness of coke layer.

Claims (1)

[Claims] 1 When charging coke and ores containing sintered ore and lump ore into a blast furnace in a predetermined ratio, the amount of coke charged per charge is divided into two, and the amount of the second charge is By adjusting the ratio of (average coke layer thickness/furnace mouth radius) to 0.10 or less, the inclination angle of the coke layer in the furnace is increased, the coke layer thickness at the furnace wall is thickened, and the ore layer is increased. A method for charging raw material into a blast furnace characterized by making the thickness relatively thin.