JPS62127411A - Raw material charging method for blast furnace - Google Patents

Abstract

PURPOSE:To improve the gas permeability, etc., of a blast furnace at all times and to permit a stable operation by simultaneously charging the ores fed onto a conveyor and the coke fed onto said ores into the furnace to form a mixed layer composed of both. CONSTITUTION:The coke (a) stocked in a scrap hopper 6 is fed onto the ores (b) fed onto the charging conveyor 2 from an ores hopper 4 and the coke and ores are conveyed in the laminated state to a furnace top charger 3. A suitable mixing stage is attained in the process of such conveyance to form the mixed ores-coke layer X dispersed with the coke (a) in the ores (b) and to simultaneously charge the coke and ores into the blast furnace 1. The mixed layers X and the coke layers Y are thus alternately formed as shown in, for example, the figure. The mixed layers X formed in the blast furnace 1 maintain the permeability of the ascending gas by the effect of the coke uniformly dispersed into the layers. The various effects of decreasing Si in iron, decreasing a coke ratio improving a gas utilizing ratio, etc., are thus obtd.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for charging raw materials into a blast furnace I.

[Conventional technology and its problems]

In the operation of a blast furnace, maintaining the gas distribution and ventilation inside the furnace in an appropriate state and efficiently utilizing the sensible heat and reducing ability of the gas are the key to stable and good operation.
There are two important conditions. In general, it is known that gas distribution and permeability are greatly affected by the raw material properties themselves as well as the charging conditions of the raw materials, and in blast furnace operation, it is important to properly adjust and manage the distribution of the contents in the furnace. consideration is given. For this reason, conventionally, the raw material charging section l at the top of the furnace
A charging device such as a movable armor and a distribution chute is installed, and using these charging devices, the charging distribution of ores and coke, that is, the charging thickness, thickness ratio, etc., is adjusted to alt4%E, and the air permeability is and gas distribution. However, in the past, the effects of such adjustments have not always been sufficient, and the reality is that in particular, sufficient effects cannot be achieved with respect to air permeability.

[Means to solve the problem]

The present invention was devised in view of these circumstances, and aims to provide a new raw material charging method that can improve the ventilation inside the furnace.

Regarding the relationship between the structure of the in-furnace layer and air permeability, it is known that the softened and molten zone inside the furnace inhibits the air permeability of rising gas, but according to research by the present inventors, It has been found that by making the ore layer formed by charging into the furnace a coke-containing ore layer in which an appropriate amount of coke is dispersed and mixed into the ore, air permeability can be improved to a degree that is favorable for operation. did. This improvement in air permeability is presumed to be due to the effect of the mixed coke present in the softened and molten zone. However, when mixing coke into the ore layer, which has the effect of improving air permeability, the amount of coke mixed in must be adjusted as necessary, and the dispersibility of a certain degree of S in the ore layer must be ensured. In order to meet these conditions and apply it to actual blast furnace operation, it is necessary to adopt a charging method that is compatible with the actual operating conditions and equipment.

For this reason, the present invention aims to provide a specific raw material charging method based on the knowledge that the coke-containing ore layer is effective in improving air permeability.

For this reason, the present invention focuses on the scrap hopper installed downstream of the ore hopper on the charging conveyor line, and stores the scrap coke in this scrap hopper and cuts the ore directly onto the charging conveyor. The basic idea is that coke is cut out from a scrap hopper onto the ores, and the ores and coke are simultaneously charged into the furnace, thereby forming an ore-coke mixture in the furnace. Features.

Usually, a raw material charging line for a blast furnace is equipped with a scrap tank and a scrap hopper for using iron scrap as part of the raw material. Iron scrap is placed on the charging conveyor. There is a problem with damaging the conveyor belt if the scrap is cut directly, so the scrap hopper is always installed on the most downstream side of the ore hopper on the charging conveyor, and the scrap hopper is always installed at the most downstream side of the ore hopper on the charging conveyor. The present invention utilizes such scrap cutting equipment as it is for cutting out coke. can be cut out. The coke cut out in this way is transported to the furnace top charging device in a layered state with the ores at the bottom, and the coke and ores are mixed appropriately during the charging process into the furnace. At t15, an ore-coke mixed layer is formed in the furnace.

Figure 1 shows blast furnace equipment to which the method of the present invention is applied.
(1) is a blast furnace, (2) is a charging conveyor, (3) is a top charging device, and (4) is an ore hopper (usually an ore storage hopper) for cutting ores onto the charging conveyor. )
, (5) is a coke hopper (usually a coke weighing hopper') for cutting out coke, (6) is a scrap hopper provided between the ore hopper (4) and the coke hopper 151, and (7) is a scrap hopper for storing scrap. This is a scrap tank. In addition, (8) is an ore section tank, (9) is an ore weighing hopper, [10 is an ore cutting conveyor, αD
is a coke tank, (2) is a coke cutting conveyor, (to)
is a feeder.

FIGS. 2 and 3 show the implementation status of the present invention. In the present invention, coke is stored in the scrap tank (7), and as shown in FIG. Coke (a) is cut out from the scrap hole tzU (6), and ore (b) and coke (a) are piled up on the ore (b) cut from the scrap hole (6). and transported to the furnace top charging device (3). Coke is cut out from the scrap hopper (6), for example, from the ore hopper (4) located upstream of the conveyor.
is cut out, and this ore (b) is transferred to the charging conveyor (2) i
When the scrap hopper (6) is conveyed and reaches the lower part of the scrap hopper (6), the coke (a) starts to be cut out, and the coke is piled on top of the ores (b). The ores (b) and coke (a) cut out in a layered manner on the charging conveyor (2) in this way are in a suitable mixed state when they are charged into the furnace and left, and the coke is mixed in the ores. An ore-coke mixture, 1, with dispersed minerals and coke is formed.

In the examples shown in Figures 2 and 3, the ore-coke mixed layer (
X) is formed by charging alternately with the coke layer (Y),
The coke layer (Y) is charged and formed by cutting out from a coke hopper (5).

In the present invention, the coke mixing ratio in the ore-coke mixed layer (X) can be arbitrarily adjusted by adjusting the amount of coke cut out onto the charging conveyor (2), and the coke amount can be adjusted as desired. At the same time, the cutting timing of the hopper is appropriately controlled, for example, in Fig. 4 (a) and (
By appropriately selecting the lamination mode as shown in b), it is also possible to arbitrarily control the distribution state (radial distribution, etc.) of coke (a) in the ore-coke mixed layer (X). It is possible.

The ores on the charging conveyor (2) are usually conveyed in such a form that sintered ore, auxiliary raw materials, and B lumps can be distinguished, as shown in Figure 5. Therefore, by controlling the scrap hopper, for example, as shown in Fig. 5 (a) I, coke is cut out only in the B boundary portion where reducibility is poor.
Alternatively, as shown in FIG. 3(B), a method such as increasing the coke cutting current in that part may be adopted.

It goes without saying that the amount of coke mixed into the ores mentioned above occupies a part of the total amount of coke to obtain the ore to coke ratio necessary for stable operation of the blast furnace. Subject to regulations from this aspect.

In the present invention, the charging form of the raw materials can be selected as appropriate, for example, a mode in which the ore-coke mixed layer (X) is charged and formed alternately with a coke layer and an ore layer, or a mode in which the ore-coke mixed layer (X) is charged and formed alternately with a coke layer and an ore layer. It is possible to adopt an embodiment in which charging is carried out, or an embodiment in which an ore-coke mixed layer is charged and formed in the entire furnace.

When the ore-coke mixed layer (X) formed in the furnace as described above reaches the softened molten zone in the lower part of the blast furnace,
The effect of the coke uniformly dispersed in the layer maintains the permeability of the rising gas, thereby suppressing a decrease in the permeability in the furnace caused by the softening and melting zone. It has also been found that in addition to the effect of improving air permeability, various effects such as a reduction in Sl in the pig iron, a reduction in coke ratio, and an improvement in gas utilization efficiency can be obtained.

〔Example〕

Table 1 shows an example of operation in which the method of the present invention was implemented in comparison with an example of operation before implementation, and the raw material charging (C : coke, 0: ores), CLC↓0↓ based on the method of the present invention
This was carried out as (Co)mix↓. This shows that in the operation in which the method of the present invention was implemented, the blowing pressure was reduced and the air permeability was improved.

In addition, in the operation in which the charging method of the present invention was implemented, a reduction in the ST in pig iron, a reduction in the coke ratio, and an improvement in the gas utilization rate were observed compared to the operation before implementation.

Table 1 [Effects of the Invention] According to the present invention described above, an ore-coke mixed layer can be stably formed in a blast furnace while maintaining coke dispersibility of 1, and the blast furnace can be ventilated. This is to enable stable operation by constantly improving performance, etc.

[Brief explanation of drawings]

FIG. 1 is an overall explanatory diagram of blast furnace equipment to which the method of the present invention is applied. FIGS. 2 and 3 show the state of implementation of the present invention, with FIG. 2 being an overall explanatory diagram, and FIG. 3 being an explanatory diagram showing the charging of raw materials in a blast furnace. FIGS. 4A and 4B are explanatory diagrams showing an example of the raw material type 1 state on the conveyor in the present invention. FIGS. 5(A) and 5(B) are explanatory diagrams showing an example of the state in which raw materials are stacked on a conveyor according to the present invention. In the figure, (1) is the blast furnace, (2) is the charging conveyor, (
4) is an ore hopper, (6) is a scrap hopper, (a
) is coke, (b) is ore, and (X) is ore-coke mixed layer. Patent applicant Nippon Kokan Co., Ltd. Figure 3

Claims (1)

[Claims] Ore hopper on the charging conveyor line (In a raw material charging method in blast furnace equipment with a scrap hopper located downstream, coke is stocked in the scrap hopper and cut from the ore hopper onto the charging conveyor.) Coke is cut from the scrap hopper onto the ores,
1. A method for charging raw materials in a blast furnace, characterized by forming an ore-coke mixed layer in the furnace by simultaneously charging the ores and coke into the furnace.