JPH0442446B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for charging raw materials into a blast furnace having a bell-type raw material charging device. More specifically, the present invention includes:
When charging raw materials into a blast furnace equipped with a bell-type raw material charging device, an opening that can be opened and closed is installed on the surface of the large bell.
This relates to a raw material charging method for a bell-type blast furnace in which a part of the raw material deposited in a large bell hopper is directly charged into the center of the blast furnace by opening the opening at a predetermined time. This invention discloses a raw material charging method that allows accurate control of the weight ratio of coke (hereinafter abbreviated as O/C) and/or the particle size of the charged material.

Conventional technology In blast furnace operation, the radial distribution of O/C, particle size, etc. of the charge at the top of the blast furnace is appropriately controlled, and the radial gas flow distribution and heat flow ratio distribution in the furnace are controlled to a predetermined level. It is necessary to maintain the concentration within this range to ensure stable reduction and dissolution of the ore.

A conventional bell-type raw material charging method will be explained with reference to FIG.

FIG. 2 is a schematic diagram of a raw material charging device at the top of a bell-type blast furnace. As shown in the figure, a conveying means such as a belt conveyor 2 is attached to the top of the blast furnace 1 from outside the furnace to the inside of the furnace, and below the belt conveyor 2 there is a fixed structure for storing the raw material 3 conveyed by the belt conveyor 2. A hopper 4 is provided. The lower part of the fixed hopper 4 is closed by a seal valve 5. A swing chute 6 is provided below the seal valve 5, and a small bell 7 is further arranged. The small bell 7 can be moved up and down by a small bell rod 8, and the material 3 deposited on the small bell 7 is configured to accumulate or fall. A large bell 9 is further provided below the small bell 7.
is movable up and down by a large bell rod 10, and is configured so that the raw material 3 deposited on the large bell 9 accumulates or falls. The raw material charging device at the top of the furnace further includes a movable armor 11 below the large bell 9, and is configured to adjust the position of the raw material 3 falling from the large bell 9 by adjusting its inclination angle.

Therefore, in the conventional bell-type raw material charging apparatus shown in FIG. 2, raw materials are charged into the furnace as follows.

First, the raw material 3 conveyed to the top of the furnace by the belt conveyor 2 is temporarily stored in the fixed hopper 4. Thereafter, the seal valve 5 is opened and the raw material 3 is evenly charged onto the small bell 7 via the rotating chute 6. Next, the raw material 3 is charged onto the large bell 9 by opening the small bell 7 by operating the small bell rod 8. Furthermore, when the level of the charge reaches a predetermined position (stock level) in the blast furnace 1, the charge in the large bell hopper is lowered down the large bell slope by the operation of the large bell rod 10, and is charged into the furnace. be done. At this time, the movable armor 11 is operated to control the position where the charge falls into the furnace.

However, the conventional bell-type raw material charging method has the following problems. In other words, although the movable armor 11 is used to control the falling position of the raw material in the furnace, the falling position of the raw material can only be adjusted by operating the movable armor 11 up to the midpoint between the furnace center and the furnace wall. It is. For this reason, in actual operations, the charging material is often dropped near the furnace wall.

Therefore, the raw material charged near the furnace wall moves by its own weight on the slope of the already deposited raw material and reaches the center of the furnace. The raw materials deposited in the center of the blast furnace in this way are not directly charged from the large bell, but are first charged near the furnace wall, move down the slope, and are indirectly charged. be done.

For indirect charging of raw materials into the center of the furnace,
There are the following problems.

In other words, when ore is charged, a part of the surface of the coke layer deposited near the ore falling position is scraped off by the impact energy of the ore falling, moves toward the center of the furnace while mixing with the ore, and moves toward the center of the furnace. Forms an extensive mixed layer near the area. For example, Y. Transactions of Iron by Y. Kajiwara et al.
and Steel Institute of Japan) Volume 23 1983
See page 1045.

Therefore, in the conventional blast furnace raw material charging method, the O/C at the center of the furnace is much lower than the O/C calculated from the deposition angle of ore and coke.

Secondly, since the raw material is reclassified on the slope while moving from the vicinity of the furnace wall to the center of the furnace, raw materials with large particle sizes are deposited in the center of the furnace. This phenomenon occurs with both ores and coke, but in the case of ores containing sintered ore with a wide particle size distribution, the tendency for coarse particles to concentrate in the center of the furnace becomes more pronounced.

In this way, the center of the furnace is exposed to O/O due to the mixed layer formation.
Gas permeability tends to become excessive due to a decrease in C and an increase in particle size due to reclassification. For stable operation of a blast furnace, it is important to ensure adequate gas permeability in the center of the furnace. This is undesirable because not only will the gas and ore balance in the radial direction be disrupted, but the fuel ratio will also deteriorate.

However, the extent of the above two phenomena, namely mixed layer formation and reclassification on the slope, depends on the conditions of the blast furnace raw material (adjustment of particle size distribution, cold strength, etc.) and charging conditions (movable armour notch, stock level, coke base, etc.). Although it is known that changes occur due to changes in the amount of ore charged, etc., it is currently difficult to estimate them quantitatively, as well as items that are not routinely detected using current detection methods. There is also. Although the raw material charging conditions are relatively fixed, the raw material properties fluctuate on a daily basis, and it cannot be said that O/C in the center of the furnace and particle size can be accurately controlled.

Furthermore, a method for improving the O/C distribution in the radial direction inside the furnace is disclosed in JP-A-60-56003, but in this conventional method, ore and coke are charged alternately; There is no disclosure of a simple method for directly charging raw materials into the center of the furnace.

Problems to be Solved by the Invention The purpose of the present invention is to solve the above-mentioned problems of the conventional bell-type raw material charging method, and more specifically, to improve the conventional bell-type raw material charging method. ,
By directly charging a portion of the raw material deposited in the large bell hopper into the center of the furnace, the O/C and particle size of the raw material in the center can be precisely controlled, and the gas flow distribution in the radial direction can be controlled accurately. The aim is to achieve stable blast furnace operation by appropriately controlling the heat flow ratio distribution.

Means for Solving the Problems The present invention has been made to solve the problems of the conventional bell-type raw material charging method described above. A bell-type raw material charger that accurately controls O/C and/or grain size in the center of the blast furnace by directly charging a portion of the raw material deposited in the blast furnace through the opening into the center of the blast furnace. It provides a method of entry.

That is, according to the present invention, in the raw material charging method for a blast furnace having a bell-type raw material charging device, an opening that can be opened and closed is provided on the surface of the large bell, and the large bell is kept in a closed state at the initial stage of loading the raw material into the furnace. The raw material is deposited in the large bell hopper, and in this state, the opening is opened to allow the raw material to fall directly from the opening to the center of the blast furnace, and after the middle of charging, the opening is closed and the large bell is opened. Provided is a method for charging raw materials into a bell-type blast furnace, which is characterized in that raw materials deposited in a large bell hopper are charged into an intermediate portion and a furnace wall portion of the blast furnace.

Effect According to the method of the present invention, raw materials can be directly charged into the center of the furnace, so O/C at the center of the furnace can be charged directly.
and/or particle size, i.e. O/C and/or particle size can be precisely controlled over the radial direction within the furnace. In other words, in the method of the present invention, raw materials can be directly charged into the center of the furnace simply by providing an opening that can be opened and closed on the surface of the large bell and controlling the opening and closing of the opening, which requires a simple device. Just need it.

According to the present invention, by controlling O/C and/or particle size in the radial direction of the furnace, the gas flow distribution and heat flow ratio distribution in the radial direction of the furnace can be properly controlled.
Stable blast furnace operation can be achieved by optimizing the shape of the softened cohesive zone inside the furnace.

EXAMPLE An example of the raw material charging method according to the present invention will be explained based on FIG.

FIG. 1 is a schematic diagram of a bell-type raw material charging device for carrying out the method according to the invention. The same members as those in the bell-type raw material charging device shown in FIG. 2 that have already been described are indicated by the same reference numerals, and detailed explanation thereof will be omitted.

That is, according to the present invention, a plurality of openings 12 that can be opened and closed are provided on the surface of the large bell 9, and the openings 12
A guide plate 13 and a guide tube 14 connected to the guide plate 13 are provided so as to guide the raw material 3 that has entered the large bell 9 from the inside to fall into the furnace.

The raw material charging method of the present invention will be explained.
The process until the raw material is charged is the same as the conventional method described above, so the explanation will be omitted.

That is, when the raw material is charged onto the large bell 9 and the level of the charge in the blast furnace 1 reaches the stock level, the large bell 9 remains closed and the opening 12 installed on the surface of the large bell is opened. The drive device shown in FIG. 3 and described later is operated to open, and a part of the raw material in the large bell hopper is passed through the opening 12 and then onto the guide plate 13 installed inside the large bell and the bottom of the large bell. It is directly charged into the center of the blast furnace through the installed guide pipe 14. The part indicated by reference number 15 in FIG. 2 is the raw material directly charged into the center of the blast furnace by this method.

Next, after closing the opening 12 and stopping the charging of raw materials into the center of the blast furnace, the large bell 9 is inserted into the large bell rod 10.
is opened, and all of the raw materials remaining in the large bell hopper are charged into a predetermined position near the furnace wall via the movable armor 11. The part indicated by reference number 16 in FIG. 2 shows the raw material deposited from the furnace wall to the intermediate part of the blast furnace by this method.

In this way, if raw materials are directly charged into the center of the blast furnace from the opening installed on the surface of the large bell using the method of the present invention in a concentrated manner at the initial stage of charging, the O/C at the center can be reduced.
This method not only allows accurate control without being affected by the formation of a mixed layer during ore charging, as in the conventional raw material charging method, but also allows the raw material that was previously deposited in the center to flow into the furnace through the movable armor. This acts as a dam for the charged raw material, controls reclassification on the slope of the pile, and alleviates the increase in grain size in the center. As a result, the O/C and particle size at the center of the furnace can be accurately controlled, the radial gas flow distribution and heat flow ratio distribution can be appropriately controlled, and stable blast furnace operation can be achieved.

Next, a specific example of the opening provided on the surface of the large bell will be described in detail.

FIG. 3 is a detailed view of the large bell opening used in the method of the invention. As shown in the figure, the large bell 9 has a hollow bell shape, and has a plurality of openings 12 on its side surface.
Equipped with. A frustoconical side plate 17 having an opening having the same shape as the opening 12 is held by the guide rail 18 at a position corresponding to the opening 12. Further, the side plate 17 is rotatable while being guided by a guide rail 18. Therefore, the side plate 17 is connected to the large bell rod 10 by a connecting rod 19, and is configured to rotate as the large bell rod 10 rotates around its axis. Inside the large bell 9, an inverted truncated conical guide plate 13 connects the opening 20 provided on the lower surface of the large bell 9 from the lower part of the opening 12 so as to guide the raw material entering from the opening 12. It is set in.
Furthermore, a guide tube 14 is provided in the opening 20,
The raw material is guided to fall into the center of the furnace directly below.

Therefore, by adjusting the area of the overlapping portion between the opening of the side plate 17 and the opening of the large bell, the speed of charging the raw material into the center of the blast furnace can be controlled. The side plate 17 is driven by a connecting rod 19 fixed to the side plate connected to a large bell rod 10, and by rotating the large bell rod about the axis of the rod by a drive device (not shown).

FIG. 4 shows large bells having openings 12 of various shapes. That is, the opening 12 may be circular as shown in FIG. 4a, or rectangular as shown in FIG. Any shape may be used as long as it does. Furthermore, Figure 4c
As shown in the figure, it is also possible to provide a sieve in the opening to prevent coarse raw materials from being charged into the center.

Effects of the Invention In order to confirm the effects of the present invention, a fan-shaped cold material charging device having the same shape and dimensions as the large bell and forming an angle of 20° was manufactured outside the furnace. The raw materials used in the test were those used in actual blast furnaces, and the charging conditions were the same as in actual blast furnaces, except that the charging conditions were only in the fan-shaped section and there was no air blowing. The O/C and particle size distribution in the radial direction were measured by solidifying the charged raw material with epoxy resin and taking it out of the apparatus. The amount of raw material charged into the center is the amount of raw material charged within 1.0 m from the center.
Adjusted so that the center O/C was 3.5.

Measure the radial O/C distribution and ore particle size distribution between a portion corresponding to the furnace center and a portion corresponding to the furnace wall,
The results are shown in FIGS. 5 and 6. In FIGS. 5 and 6, the solid line shows the results obtained by the method of the present invention, and the broken line shows the results obtained by the method of the prior art.

As shown in Figure 5, in the conventional material charging method, the O/C at the center of the furnace is extremely low, but in the method of the present invention, the O/C at the center of the furnace is 3.6, which is almost as originally planned. O/C has been obtained. Of course, if it is desired to further reduce the O/C in the center of the furnace, this can be easily achieved by reducing the amount of ore charged through the opening of the large bell and increasing the amount of coke.

Regarding the grain size distribution of ore in the radial direction inside the furnace, as shown in Figure 6, in the conventional method, the grain size in the center becomes extremely large due to reclassification while moving on the slope of the deposit inside the furnace. ing. On the other hand, it can be seen that in the method of the present invention, the grain size in the center is approximately equal to the average grain size in the entire furnace. Of course, if it is desired to further change the central particle size, a sieve mesh may be provided in the opening as shown in Figure 4c, or raw materials with a predetermined particle size may be deposited at the bottom of the large bell hopper. This can be easily achieved by changing the sequence.

As explained above, the present invention has succeeded in directly charging raw materials into the center of the furnace, and the method of the present invention allows controlling O/C and/or particle size throughout the radial direction of the furnace. However, the gas flow distribution and heat flow ratio distribution in the radial direction inside the furnace can be properly controlled, and the shape of the softened cohesive zone inside the furnace can be optimized to achieve stable blast furnace operation. Furthermore, in order to carry out the method of the present invention, it is sufficient to simply modify the large bell of the current blast furnace bell-type material charging device, and the equipment cost is extremely low.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a bell-type raw material charging device for carrying out the method according to the present invention, FIG. 2 is a schematic diagram of a conventional bell-type raw material charging device, and FIG. 3 is a diagram of a large bell-type raw material charging device. Fig. 4 a, b, c
1 and 2 respectively show examples of large bell openings of bell-type raw material charging equipment for carrying out the method according to the invention, and
Figure 5 is a graph showing the measurement results of the radial O/C distribution in the cold charging test, and Figure 6 is a graph showing the measurement results of the radial ore particle size distribution in the cold charging test. be. Main reference numbers: 1...Blast furnace, 2...Belt conveyor, 3...Raw material, 4...Fixed hopper, 5...
Seal valve, 6...Swivel chute, 7...Small bell,
8...Small Bell Rod, 9...Large Bell, 10...Large Bell Rod, 11...Movable Armor, 12...
…The opening of the large bell.

Claims (1)

[Claims] 1. In a raw material charging method for a blast furnace having a bell-type raw material charging device, an opening that can be opened and closed is provided on the surface of a large bell, and the raw material is deposited in a large bell hopper with the large bell closed, and the raw material is loaded into the furnace. Initially, the opening is opened with the large bell closed to allow the raw material to fall directly from the opening into the center of the blast furnace, and after the middle stage of charging, the opening is closed and the large bell is opened.
A method for charging raw materials into a bell-type blast furnace, characterized in that raw materials deposited in a large bell hopper are charged into an intermediate portion and a furnace wall portion of the blast furnace.