JP2600803B2 - Blast furnace raw material charging method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method in which a blast furnace raw material is charged by a bell-type or bell-less type charging device, without using the charging device, by a different route to a central portion in the furnace. The present invention relates to a blast furnace raw material charging method for directly charging a part of a blast furnace raw material.

[Conventional technology]

In blast furnace operation, the ore / coke weight ratio in the radial direction of the furnace (hereinafter, this ratio is abbreviated as O / C) is controlled with high accuracy, and the gas flow distribution in the furnace, the shape of the cohesive zone, etc. are controlled within the target range. It is important to maintain the blast furnace within a stable operation of the blast furnace.

For this reason, conventionally, in a blast furnace equipped with a bell-type charging device, the O / C in the radial direction in the furnace is controlled by independently controlling the setting position of the rubble armor with ore and coke.
In a blast furnace equipped with a bellows-type charging device by controlling the distribution, the O / C distribution in the radial direction in the furnace is controlled by adjusting the tilt angle of the distribution chute.

However, in the former control based on the movable armor setting position, the impact energy held by the ore at the time of ore charging causes part of the surface layer of coke already deposited in the furnace to collapse, and It is known that it flows into the central part of the furnace and forms a mixed layer of ore and coke in this part (eg, Y.KAJIWARA et al., Transact
ions of the Iron and Steel Institute of Japan 23
1983 p. 1045).

And the layer collapse of this coke is ore charging amount, ore particle size composition, movable armor position, coke oven deposition angle,
It changes variously depending on various factors such as stock level,
Since it is difficult to make a specific prediction, the control accuracy of the O / C distribution in the radial direction inside the furnace particularly at the center of the furnace is significantly deteriorated.

Further, in the latter control by the tilt angle of the distribution chute, by setting the tilt angle of the distribution chute to be small, the raw material can be charged more centrally in the furnace than in the former control by the movable armor, and the O in the furnace radial direction can be set. / C distribution controllability can be improved. However, if the deposition angle after charging coke exceeds 15 °, the collapse of the coke layer during charging of the ore becomes remarkable, as in the former control, and the O / C distribution in the furnace radial direction at the center of the furnace Decreases controllability.

Therefore, recently, a method of directly charging and depositing a part of the raw material into the center of the blast furnace by another route (specifically, a charging chute or the like) without using a bell-type or bell-less charging device has been proposed. Developed (Japanese Utility Model Application Laid-Open No. 61-120743,
No. 61-227109).

According to this method, the O / C controllability particularly at the center of the blast furnace is improved as compared with the case where only the bell type or bellless type charging device is used. When the O / C is controlled with high precision in the central part of the blast furnace, the gas utilization rate is improved in this part, and the fuel ratio of the blast furnace can be reduced.

[Problems to be solved by the invention]

However, when ore and coke are charged into the center of the blast furnace by this method, there is a problem that the gas utilization rate in this portion is not improved as expected, and the fuel ratio of the blast furnace cannot be sufficiently reduced. There was found.

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

[Means for solving the problem]

Regardless of the bell type or bellless type charging equipment, if a part of the raw material is independently charged into the center of the blast furnace by another route, the desired O / C can be applied to the center of the blast furnace, and gas is used in this part Various effects should be obtained, such as a drastic improvement in the rate. However, the effect as expected is not actually obtained as described above.

The present inventors investigated and investigated the cause, and found that the charging of raw materials into the center of the blast furnace by another route was performed by layered charging of ore and coke, as in the surrounding area. I found that there was.

That is, if layered charging of ore and coke is performed in the center of the blast furnace, ore and coke are charged alternately in a narrow area of the center of the blast furnace, and the bulk density of the raw material is reduced even if charging is performed by another route. It is inevitable that the deposition range and the deposition angle of the raw material charged in the center will fluctuate due to fluctuations, fluctuations in particle size, fluctuations in the gas flow rate in the center, etc.
Local control of O / C becomes difficult. If local O / C control in the central part of the blast furnace becomes difficult, fluctuations in gas flow rate and gas temperature in this part become large, and the gas utilization rate is not improved, making it difficult to lower the fuel ratio of the blast furnace. Becomes

Therefore, the present inventors have further studied. as a result,
The raw material charging into the central part of the blast furnace by another route is performed independently of the raw material charging into the peripheral part by the bell type or bellless type charging equipment. It was also possible to obtain the desired O / C at the center of the blast furnace.

The blast furnace charging raw material method of the present invention has been developed based on the above findings, and prior to the ore and coke being layeredly charged into a blast furnace by a bell-type or bell-less charging device, the ore and coke are mixed. The above-mentioned bell-type or bell-less type charging is performed by mixing a mixture obtained by mixing a part of the iron source and the carbon material at a predetermined weight ratio or a completely mixed raw material comprising a composite of the iron source and the carbon material at a predetermined weight ratio. By using a charging system of another route that does not depend on any of the equipment, charging and stacking are performed so that charges to be charged later in layers are removed from the center of the blast furnace so that they are raised in the center of the blast furnace. The purpose of the present invention is to improve the control accuracy with respect to the target value of the (ore / coke) weight ratio at the center.

[Action]

In the method of the present invention, a completely mixed raw material whose O / C has been determined in advance is charged by another route so that a charge to be layered later is removed from the center of the blast furnace so as to be removed from the center of the blast furnace. By doing so, the completely mixed raw material will be present in the center of the blast furnace. This completely mixed raw material has little room for fluctuation in O / C after the charging as well as in the charging stage. As a result, the accuracy of controlling the target value of O / C at the center of the blast furnace is increased, and
O / C can be provided. In the present specification, O
The controllability of / C means O / C, that is, the control accuracy for the target value of (ore / coke) weight ratio, and the high controllability means that O / C is managed to the target value with high accuracy. That is, it means that O / C as intended is provided.

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

〔Example〕

FIG. 1 is a schematic view of the case where the present invention is applied to a blast furnace provided with a bell-type charging device.

The top of the blast furnace is provided with a bell-type charging device 1 composed of a large bell and a small bell, and a charging chute 2 that penetrates the furnace wall and has a tip facing the center of the blast furnace.

In the case of FIG. 1, before mixing ore 3 and coke 4 as blast furnace raw materials in a bell type charging apparatus 1 from the furnace top into the furnace interior charging surface 5, the mixed raw material 6 is charged into the charging chute 2. Into the furnace interior entrance surface 5 at the center of the furnace. As a charging mode at this time, as shown in the figure, the ore 3 and the coke 4 which are layered later are removed from the furnace center, and the furnace center is occupied by the mixed raw material 6. The mixed raw material 6 is charged on the furnace interior entrance surface 5 at the center of the furnace so as to raise the ore 3 and the coke 4 to the same layered thickness. When the mixed raw material 6 is charged into the central portion of the furnace, the ore 3 and the coke 4 are charged into the peripheral portion thereof in a layered manner. Then, the charging of one unit of raw material is repeated.

The mixed raw material 6 is a raw material in which the ore 3 and the coke 4 to be charged in the peripheral portion of the furnace are mixed at a predetermined weight ratio in advance, or iron obtained by agglomerating an iron source and a carbon material at a predetermined weight ratio in advance. source·
It is a carbon composite.

When the former mixed raw material 6 is used, the ore 3 and the coke 4 are slightly separated at the time of charging, but the O / C is much more accurate than the case where the ore 3 and the coke 4 are layeredly charged.
Is applied to the center of the furnace. When the latter mixed raw material 6 is used, there is no raw material separation at the time of charging, and the intended O / C is given to the center of the furnace.

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

The iron source in the iron source / carbon material composite is fine ore, fine sintered ore, dust containing iron, and the like, and the carbon material is dust containing fine coal, coke fine, and carbon material. For both agglomeration means, a pellet method, a cold bond briquette method using a binder, or the like can be applied.

FIG. 2 is a schematic view of the case where the present invention is applied to a bellless type blast furnace. Is separately provided.

The basic procedure for applying the present invention to this blast furnace is the same as that for applying the present invention to a bell blast furnace.

That is, before the ore 3 and coke 4 are layeredly charged on the furnace interior charging surface 5 by the bellless type charging apparatus 7, the mixed raw material 6 is charged into the furnace center by the charging chute 2 and the furnace center is charged. The charging of the mixed raw material 6 into the part and the layered charging of the ore 3 and the coke 4 into the peripheral part thereof are defined as one unit, and this is repeated. The mixed raw material 6 is as described in the application example of the present invention to a bell blast furnace.

Next, the results of implementation of the present invention will be described with reference to FIGS. 1 and 2. FIG.

First, internal volume 4800m ³ , furnace diameter 10.8m, distribution chute length 4
A full-scale model of the furnace top of an 800 mm bellless blast furnace was manufactured, and the method of the present invention was applied thereto.

The basic conditions for charging the blast furnace raw material are coke base 40t, charging O / C 3.8, and about 5% by weight of the total charge of ore and coke are mixed into the center of the furnace and routed separately. Charged directly. The management target of O / C in the central part of the furnace was set at 4.0 from the viewpoint of suppressing the gas flow rate in the central part and improving the gas utilization rate in the central part. The specific procedure for charging the raw materials is as described with reference to FIG.

In the case of the conventional method in which 5% by weight of the total charge ore and coke were separately layered at O / C 4.0 from the different route in the above full-scale model, the O / C at the center of the furnace was 3.5 to 4.4. However, according to the method of the present invention, the O / C became a small fluctuation of 3.9 to 4.1, and the charging of the mixed raw material into the center of the blast furnace by another route was difficult.
It was confirmed that it was extremely effective in improving the controllability of O / C in the center of the blast furnace.

Therefore, the method of the present invention was next carried out in a bell movable armor type blast furnace having an inner capacity of 2700 m ³ and a furnace diameter of 8.6 m.

The basic conditions for charging the blast furnace raw material were a coke base of 18 tons and a charging O / C of 3.4. However, charging into the center of the furnace by another route shall be based on a mixed raw material of ore and coke.
The charging amount was about 3% by weight of the total charging amount, and the management target of O / C in the central part of the furnace was set at 4.0 from the viewpoint of suppressing the gas flow rate in the central part and improving the gas utilization rate in the central part. The charging procedure is as described with reference to FIG. The operation results are shown in Table 1 in comparison with the conventional example in which the present invention was not carried out.

Compared with the conventional method in which ore and coke were layered and charged separately in the center of the blast furnace without applying the present invention, the O / C in the center of the furnace was almost completely maintained at the management target in the method of the present invention. The heat exchange and reaction between the gas and the ore were promoted in the furnace center, and the gas temperature in the furnace center was reduced and the gas utilization was improved. As a result, the corrected fuel ratio improved by 2 kg / pt,
Further, the gas permeability at the center of the furnace was stabilized, and it was confirmed that the fluctuation range of the gas temperature and the gas utilization rate was reduced and the slip frequency was reduced at this portion.

〔The invention's effect〕

As is clear from the above description, the blast furnace raw material charging method of the present invention, when charging a part of the blast furnace raw material by another route to the blast furnace center, the O / C The effect is significant, such as improving the gas utilization rate at the center of the furnace and lowering the fuel ratio.

[Brief description of the drawings]

1 and 2 are schematic diagrams of a blast furnace showing an application example of the present invention. FIG. 1 shows a case of a bell blast furnace, and FIG. 2 shows a case of a bellless blast furnace. In the figure, 1: Bell charging device, 2: Charging chute, 3: Ore, 4:
Coke, 6: mixed raw material, 7: bellless charging equipment.

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Chisato Yamagata 1-3-3 Nishi-Nagasu-Hondori, Amagasaki-shi, Hyogo Sumitomo Metal Industries Co., Ltd. (56) References JP-A 1-263208 JP-A-60-17004 (JP, A) JP-A-62-127409 (JP, A) JP-A-61-42896 (JP, Y2)

Claims (2)

(57) [Claims] 1. Prior to layering charging of ore and coke into a blast furnace by a bell or bellless charging device, a mixture obtained by mixing a part of the ore and coke at a predetermined weight ratio is mixed with the bell type. Or, using a charging system of another route that does not depend on any of the bellless type charging equipment, charging is carried out to build up in the center of the blast furnace so that charges to be charged later in layers are removed from the center of the blast furnace. A method for charging a blast furnace raw material, wherein the accuracy of control of a (ore / coke) weight ratio at a central portion of a furnace with respect to a target value is improved. 2. An iron source and a carbonaceous material obtained by agglomerating an iron source and a carbonaceous material at a predetermined weight ratio before the ore and coke are layeredly charged into a blast furnace by a bell-type or bellless-type charging device. The composite is placed in the center of the blast furnace so that the charge to be subsequently layered is removed from the center of the blast furnace by a charging system of another route that does not depend on either the bell type or the bellless type charging device. At the center of the furnace by charging and depositing to raise the (ore / coke)
A method for charging a blast furnace raw material, characterized by increasing the control accuracy with respect to a target value of a weight ratio.