JPH01290708A - Method of charging raw material to blast furnace - Google Patents

Abstract

PURPOSE:To impart an aimed ore/coke weight ratio (O/C) to the central part of the blast furnace and to improve the rate of utilizing gases in the central part of the furnace by charging blast furnace raw materials in another route to the central part of the blast furnace. CONSTITUTION:The raw material mixture 6 is charged onto the infurnace charging plane 5 in the central part of the furnace by a charging chute 2 of another route prior to charging of ore 3 and coke 4 in a laminar state onto the plane 5 by a bell type or bell-less type charging device 1. The ore 3 and the coke 4 are then charged in the laminar state to the peripheral part thereof. The raw material charging of this one unit is repeated. The raw material mixture 6 is the raw materials prepd. by previously mixing the ore 3 and the coke 4 at prescribed weight ratios or the iron source/carbonaceous material composits formed by lumping the iron source and carbonaceous material at prescribed ratios. The O/C of high accuracy is thereby impacted to the central part of the furnace. The mixing ratio of the raw material mixture 6 is arbitrarily set according to the purpose of the blast furnace operation such as the correct flow rate of gases in the central part.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a blast furnace raw material charging method that directly charges blast furnace raw material into the center of the furnace via a separate route without using an existing charging device such as a bell type or bellless type. Regarding how to enter.

[Conventional technology]

During blast furnace operation, the ore/coke weight ratio (hereinafter abbreviated as O/C) in the radial direction of the furnace is controlled with high precision to maintain gas flow distribution, cohesive zone shape, etc. within the target range. It is important to maintain and manage the blast furnace within a certain period of time in order to ensure stable operation of the blast furnace.

For this reason, conventionally, in blast furnaces equipped with bell-type charging devices, the O/C control in the radial direction of the furnace is controlled by independently controlling the set positions of the movable armor for ore and coke.
In a blast furnace equipped with a bellless charging device, the 070 distribution in the radial direction within the furnace is controlled by adjusting the tilt angle of the distribution chute.

However, with the former control based on the set position of the movable armor, when the ore is charged, the impact energy possessed by the ore causes a part of the surface layer of the coke already deposited in the furnace to collapse, and together with the ore. It is known that coke flows into the center of the furnace and forms a mixed layer of ore and coke in this area (for example, Y., KAJIWARA et al.
nd 5teel In5position of Jap
an, vol. 23, 1983, p. 1045).

This coke layer collapse varies depending on various factors such as the amount of ore charged, ore particle size composition, movable armor position, stacking angle in the coke oven, stock level, etc., and it is difficult to make specific predictions. This significantly deteriorates the control accuracy of the O/C distribution in the radial direction within the furnace, especially in the center of the furnace.

In addition, in the latter case, control using the tilt angle of the distribution chute,
By setting the tilt angle of the distribution chute small,
The raw material can be charged closer to the center of the furnace than in the former control using a movable armour, and the O/C distribution controllability in the radial direction of the furnace can be improved. However, if the stacking angle after coke charging exceeds 15°, as in the case of the former control, the collapse of the coke layer during ore charging becomes significant, and the O/C distribution in the radial direction inside the furnace at the center of the furnace increases. Reduces controllability.

Therefore, recently, a method has been developed to directly charge and deposit raw materials into the center of the blast furnace using a different route (specifically, a charging chute, etc.) without using existing charging equipment such as bell type or bellless type. Developed (Utility Model Application No. 61-120743,
(Japanese Patent Application Laid-Open No. 61-227109).

According to this method, compared to using only existing charging equipment such as bell type or bellless type, it is possible to
cfffl property is improved. If the O/C is controlled with high precision in the central part of the blast furnace, the gas utilization rate will be improved in this part, and the fuel ratio of the blast furnace can be lowered.

[Problem to be solved by the invention]

However, when ore and coke are charged into the center of the blast furnace using this method, the gas utilization rate in this area does not improve as much as expected, and there is a problem that the fuel ratio of the blast furnace cannot be lowered sufficiently. There was found.

An object of the present invention is to provide a method for charging raw material into a blast furnace that solves this problem.

[Means to solve the problem]

If raw material is charged into the center of the blast furnace independently using a separate route without using the existing charging equipment such as bell type or bellless type, the targeted O/C can be applied to the center of the blast furnace, and gas can be utilized in this area. Various effects should be obtained, including a significant improvement in the rate. However, in reality, as mentioned above, the expected effect is not obtained.

The inventors investigated and determined the cause of this problem, and found that it was caused by the fact that the charging of raw materials into the center of the blast furnace via a different route was carried out by layered charging of ore and coke, similar to the surrounding area. I discovered something.

In other words, if ore and coke are charged in layers at the center of the blast furnace, the ore and coke will be charged alternately in a narrow area at the center of the blast furnace, and even if charging is done through different routes, the bulk density of the raw materials will be reduced. It is inevitable that the stacking range and stacking angle of the raw material charged into the center will change due to fluctuations in grain size, particle size, center gas flow rate, etc., and as a result, the
This makes local control of /C difficult. If local 07C control in the center of the blast furnace becomes difficult, the gas flow rate and gas temperature will fluctuate greatly in this area, the gas utilization rate will not improve, and it will be difficult to lower the blast furnace fuel ratio. .

Therefore, the present inventors continued their studies further. As a result, the charging of raw materials into the center of the blast furnace via a separate route is carried out independently of the charging of raw materials into the periphery using the existing charging equipment, so pre-mixed raw materials can be charged into the center of the blast furnace. It is also possible to do this, and in this way you can get the O/O to the center of the blast furnace as desired.
We obtained knowledge that it is possible to give C.

The blast furnace charging raw material method of the present invention was developed based on the above knowledge, and prior to charging ore and coke as blast furnace raw materials into a blast furnace in a layered manner, a part of the ore and coke is charged to a predetermined weight. Raw materials mixed in different ratios, or iron and carbon material composites made by agglomerating iron and carbon materials in a predetermined weight ratio, are transferred to the blast furnace center via a separate route without using existing charging equipment such as bell or bellless methods. It is directly charged and deposited in the tank.

[For production]

In the method of the present invention, a completely mixed raw material with a predetermined O/C is independently charged into the center of the blast furnace via a separate route.
There is almost no room for O/C to fluctuate not only during the charging stage but also after charging, and the O/C is applied to the center of the blast furnace almost as desired.

In addition, in the present invention, the weight ratio of both iron source and carbon material composite is also abbreviated as O/C.

〔Example〕

FIG. 1 is a schematic diagram when the present invention is applied to a blast furnace equipped with a bell-type charging device.

The top of the blast furnace is equipped with a bell-type charging device 1 consisting of a large bell and a small bell, as well as a charging chute 2 that penetrates the furnace wall and whose tip faces the center of the blast furnace.

In the case of Figure 1, the bell-type charging device 'l! Prior to charging ore 3 and coke 4 as blast furnace raw materials onto the furnace entrance surface 5 in a layered manner, a mixed raw material 6 is loaded into the charging chute 2.
It is charged onto the furnace entrance surface 5 at the center of the furnace. Mixed raw material 6
When the ore 3 and coke 4 are charged into the center of the furnace, the ore 3 and coke 4 are charged in layers around the center. Then, this charging of one unit of raw material is repeated.

The mixed raw material 6 is a raw material prepared by mixing ore 3 and coke 4 in a predetermined weight ratio to be charged into the periphery of the furnace, or iron made by agglomerating iron source and carbon material in a predetermined weight ratio. It is a source/charcoal material combo.

When the former mixed raw material 6 is used, the ore 3 and coke 4 are slightly separated during charging, but the ore 3 and coke 4 are
O/C is much more accurate than when charging in layers.
is applied to the center of the furnace.

When the latter mixed raw material 6 is used, there is no separation of raw materials at the time of charging, and the targeted O/C is applied to the center of the furnace.

The mixing ratio in the mixed raw material 6 may be arbitrarily set according to the purpose of blast furnace operation, such as the appropriate gas flow rate in the center, but usually a value of 0.5 to 5.0 is used for O/C.

In addition, the iron source in the iron source/charcoal material composite is powdered ore, powdered sintered ore, dust containing iron, etc., and the carbon material is powdered coal, powdered coke, dust containing carbon material, etc. A pellet method, a cold bond brigett method using a binder, or the like can be applied to the forming method.

FIG. 2 is a schematic diagram of the case where the present invention is applied to a bellless type blast furnace.In addition to the bellless type charging device 7 consisting of a distribution chute and the like at the top of the blast furnace, the furnace wall is also installed. A charging chute 2 whose tip faces the center of the blast furnace is separately provided.

When the present invention is applied to this blast furnace, the basic procedure is the same as when the present invention is applied to a bell-type blast furnace.

In other words, the ore 3 and coke 4 are loaded in the bellless charging device 7.
Before charging the mixed raw materials 6 into the furnace center in a layered manner onto the furnace entrance surface 5, the mixed raw materials 6 are charged into the furnace center using the charging chute 2, and the mixed raw materials 6 are charged into the furnace center and the surrounding areas are charged. This is repeated with the layered charging of ore 3 and coke 4 set at I iJ'-position. The mixed raw material 6 is as described in the example of application of the present invention to a bell-type blast furnace.

Next, the results of implementing the present invention will be explained for the cases shown in FIGS. 1 and 2.

First of all, the internal volume is 4800n? A full-scale model of the furnace top of a bellless blast furnace with a furnace diameter of 10.8 m and a distribution chute length of 4800 t1 was manufactured, and the method of the present invention was applied to this model.

The basic conditions for charging raw materials into the blast furnace are a coke base of 40 tons and a charge of 0/C3,8, and about 5% by weight of the total amount of ore and coke are mixed into the center of the furnace and a separate route is used to charge the raw materials. Loaded directly. The control target for 0/C at the center of the furnace was set to 4.0 from the viewpoint of suppressing the gas flow rate at the center and improving the gas utilization rate at the center, and the mixed raw materials were also prepared at this ratio. The specific procedure for charging raw materials is as described in section b of Figure 2.

In the above full-scale model, in the case of the conventional method in which 5% by weight of ore and coke of the total charge were charged separately in layers with O/C4, O from a separate route, ○/C at the center of the furnace was 3.5 ~4.4
However, in the method of the present invention, 0/C was 3.9 to 4.
1, and it was confirmed that charging the mixed raw material into the blast furnace center via a different route is extremely effective in improving the controllability of the blast furnace center O/C.

Next, the method of the present invention was carried out in a bell/movable armor type blast furnace having an internal capacity of 2700+yr and a furnace diameter of 8.6 m.

The basic conditions for charging the blast furnace raw materials were a coke base of 18 tons and a charge of 0/C3,4. However, when charging to the center of the furnace via a different route, a mixed raw material of ore and coke will be charged, and the charge amount will be approximately 3% by weight of the total charge, and the charge at the center of the furnace will be 0/C.
The management target was set at 4.0 from the perspective of suppressing the gas flow rate in the center and improving the gas utilization rate in the center. The charging procedure is as explained with reference to FIG. The operational results are shown in Table 1 in comparison with a conventional example in which the present invention was not implemented.

Table 1 Compared to the conventional method in which ore and coke are layered and charged into the center of the blast furnace through separate routes, which does not apply to the present invention, the method of the present invention can almost completely maintain the O/C in the center of the furnace to the control target. As a result, heat exchange and reaction between the gas and ore were promoted in the center of the furnace, reducing the gas temperature in the center of the furnace and improving the gas utilization rate.

As a result, the corrected fuel ratio improved by 2 kg/pt, the ventilation in the center of the furnace became stable, and in this area, the range of fluctuations in gas temperature and gas utilization rate was reduced, and the slip frequency was also reduced!
It was done.

〔Effect of the invention〕

As is clear from the above explanation, the blast furnace raw material charging method of the present invention provides the targeted O/C to the blast furnace center when charging the blast furnace raw material to the blast furnace center by a different route. This has tremendous effects, such as improving the gas utilization rate in the core of the furnace and lowering the fuel ratio.

[Brief explanation of the drawing]

FIGS. 1 and 2 are schematic diagrams of a blast furnace inlet showing a general example of the present invention. FIG. 1 shows a bell-type blast furnace, and FIG. 2 shows a bell-less type blast furnace. In the figure, l: bell-type charging device, 2: charging chute, 3: ore, 4: coke, 6: mixed raw material, 7: bell-less charging device. Figure 1 Figure 2

Claims (1)

[Claims] 1. Prior to charging ore and coke as blast furnace raw materials into a blast furnace in layers, the raw material obtained by mixing a portion of the ore and coke in a predetermined weight ratio is charged in a bell type or bellless type, etc. A blast furnace raw material charging method characterized by directly charging and depositing raw materials in the blast furnace center via a separate route without using the existing charging equipment. 2. Prior to charging ore and coke as blast furnace raw materials into a blast furnace in layers, an iron source/charcoal material composite made by agglomerating iron source and carbon material at a predetermined weight ratio is placed in a bell type or bellless type, etc. A blast furnace raw material charging method characterized by directly charging and depositing raw material into the blast furnace center via a separate route without using existing charging equipment.