JPH02221308A - Method for operating blast furnace - Google Patents

Abstract

PURPOSE:To produce molten iron at a low cost by using sintered ore and coke having grain diameters in a furnace assumed with model for assuming raw material grain diameters in the furnace in the blast furnace operation. CONSTITUTION:The characteristic values of the sintered ore and the coke used as the essential raw materials at the time of operating the blast furnace, are related to the grain diameters of the raw materials, and the grain diameters in the furnace are modeled on the equation I for the sintered ore and the equation II for the coke. By using the essential raw materials of sintered ore and coke, etc., after selecting the grain diameters, based on the control reference value decided with the assumed grain diameters in the furnace assumed with the model values, even the raw material, which is treated as impossible to use heretofore, is made to be possible to use and also the production efficiencies of a sintering machine and a coke oven are improved and the molten iron is produced at a cost lower than the conventional method.

Description

[Detailed Description of the Invention] Industrial Field of Application This invention is a method for operating a blast furnace, in which charging raw materials such as sintered ore and coke are properly managed according to the grain size in the furnace, and the charging materials are controlled according to the blast furnace operating conditions. This invention relates to a blast furnace operating method that stabilizes operations and reduces raw material costs by selectively using them.

In conventional blast furnace operation, charging raw materials such as sintered ore and coke are selected and used that satisfy certain quality control standards.

For example, in the case of sintered ore, the rotational strength index (TI), low-temperature reduction pulverization index (RDI), reducibility ratio (RI), particle size, etc. are independently used as blast furnace operating indicators (number of slips, permeability, etc.). A management value is determined based on the relationship, and selection and use are made based on the management value.

In addition, for coke, the drum strength is 15712111
index (DD), drum strength 50a index (DI: ),
Control values are determined by independently relating strength index after rebound (C3R), particle size, etc. to operating indicators of the blast furnace (number of slips, air permeability, etc.), and selection and use are made based on the control values.

However, in the method of selecting and using raw materials by fixing control standard values as described above, for example, in the case of sintered ore, at least one of the control indicators such as rotational strength index, reduction rate, etc. If there is something unsatisfactory, the sintered ore has been treated as a defective product even if other management indicators satisfy the management standard values.

In addition, in the case of coke, if all properties such as the post-reaction strength index and the Yadram strength index are to be satisfied, the degree of freedom in terms of coal blending, operating efficiency, etc. tends to be narrow, and problems in terms of cost are common. Furthermore, if even one of the properties is not satisfied, it has been treated as a defective product, similar to the above-mentioned sintered ore.

In this way, in the past, if even one of the property values of charging raw material exceeded the control standard values, it was treated as a defective product, even if it was unlikely to have a negative impact on blast furnace operation, resulting in high costs. This not only causes problems, but also hinders the efficient production of sintering machines and coke ovens.

Problems to be Solved by the Invention This invention solves the problem of high costs caused by the conventional management of fixed values in which control values for each property of charged raw materials were uniquely determined by correlation with operational data. This was done to solve the problem of hindering the efficient production of sintering machines and coke ovens, making it possible to use raw materials that had previously been disposed of as defective products without affecting blast furnace operations. The purpose of this paper is to propose a blast furnace operating method that enables efficient coke oven production.

Means for Solving the Problems This invention connects the physical property values of charged raw materials such as sintered ore and coke to the grain size of the raw material in the blast furnace, estimates the grain size in the blast furnace using a model, and estimates the grain size in the blast furnace. By selecting and using the charging raw material based on the control standard value determined from the estimated particle size, costs are reduced and the yield of the sintering machine and coke oven is improved.

In other words, the gist of the present invention is to estimate the grain size of charging raw materials such as sintered ore and coke in the furnace using a charge property deterioration model, and to set the physical property values calculated from the estimated grain size in the furnace as control standard values. This blast furnace operating method is characterized in that the charging raw material is managed based on the control reference value, and the charging raw material is selectively used according to the blast furnace operating conditions.

In blast furnace operation, changes in the grain size of the charge inside the furnace are considered to be an important factor that affects unloading, air permeability, etc., and a charge property deterioration model has been developed as a method for estimating the grain size inside the furnace. It was done.

The model for estimating the raw material particle size in the furnace is shown below.

sintered ore D. Estimated grain size of sintered ore in the shaft part DO initial particle size Pro Blast furnace tap ratio TI Rotational strength index RI Refund rate RDI Low temperature reduction powdering index coke> L3K dKr.

Dc Bosch section coke estimated particle size Do Initial particle size D! := Drum strength 158 index DI:: Drum strength 50m index C5R strength index after rebound pro Blast furnace tapping ratio Figure 1 shows the relationship between the rotational strength index (TI) of sintered ore and the sintered ore particle size in the blast furnace shaft. This figure shows that as TI increases, cold strength increases.

Therefore, it is shown that the decrease in grain size due to impact at the large bell, small bell, belt conveyor transition area, etc. is reduced, and the sintered ore grain size at the shaft portion becomes larger.

FIG. 2 is a diagram showing the relationship between the reduction ratio (RI) and the shaft portion sintered ore grain size, and shows that as the RI increases, the reaction becomes easier and the grain size becomes smaller.

FIG. 3 is a diagram showing the relationship between the low-temperature reduction pulverization index (RDI) and the shaft portion sintered ore grain size, and shows that as the RDI becomes smaller, the sintered ore becomes easier to powder and the shaft portion grain size becomes smaller.

Figure 4 shows the grain size of the sintered ore in the shaft section and the lower belly stage (upper part of the furnace).
A diagram showing the relationship between the inert zone thickness and FIG. 5 is a diagram showing the relationship between the coke particle size and the Bosch part (furnace middle) inert zone thickness,
It can be seen that the sinter grain size has a strong relationship with the inert zone thickness in the lower Berry section, and the coke with the inert zone thickness in the Bosch section.

In this invention, the in-furnace raw material particle size is estimated using the above equation (1) in the case of sintered ore, and the above-mentioned equation (2) in the case of coke, and each raw material calculated from the estimated in-furnace particle size (constant). The physical property values are determined as control standard values.

For example, taking sintered ore as an example, conventionally the control standard value for sintered ore was set as TI≧72 based on the correlation with operational data. RDI≦40
．． If it is determined that RI≧60, then TI is 75. RDI
The finished sintered ore with 42° and RI of 60 was treated as a defective product because the RDI was outside the above control standard value, but in the case of the present invention, the TI and RDI of the finished sintered ore are calculated according to the formula (1) above.
, Substituting RI and conversely determining RDI, RDI≦
45, and the sintered ore becomes usable.

EXAMPLE A The operating conditions and sintered ore quality when the method of the present invention was applied to the operation of a blast furnace (volume 1850 m'', sedimentation index 1.1) are shown in FIG.

In period A in the figure, the in-furnace particle size tended to decrease due to increases in the tuyere wind speed and tuyere front temperature due to increased blast furnace production.

Additionally, during this period, the sintering factory also increased production, making it difficult to secure TI.

Therefore, by fixing Tl-72%, which is possible under the current situation, and deriving RDI-40% from the model calculation results shown in Figure 1, we adjusted the fuel coke blending ratio in the sintering process, etc. % of sintered ore was produced and the sintered ore was used to ensure stable blast furnace conditions.

In addition, during period B, due to the period of reduced blast furnace production, the tuyere wind speed
As the air volume etc. decreased and the grain size in the furnace tended to increase, in order to reduce the cost of sintered ore, a large number of inexpensive raw materials were mixed.
Sintered ore with poor TI and RDI was used. During this period, the blast furnace was able to maintain stable operation.

As described in detail, this invention uses the in-furnace particle diameters of sintered ore and coke estimated using a model for estimating the raw material particle diameter in a blast furnace, and calculates control standard values for sintered ore and coke. As a result, raw materials that were previously disposed of as defective can now be used without affecting blast furnace operations, reducing raw material costs and enabling efficient production of sintering machines and coke ovens. It has a great economic effect.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the rotational strength index (1) of sintered ore and the grain size of sintered ore in the blast furnace shaft, and Figure 2 is a diagram showing the relationship between the rotational strength index (1) of sintered ore and the particle size of sintered ore in the blast furnace shaft.
) and the sintered ore particle size at the blast furnace shaft, Figure 3 is a diagram showing the relationship between the low temperature reduction index (RDI) and the sintered ore particle size at the blast furnace shaft, and Figure 4 is the relationship between the sintered ore particle size at the blast furnace shaft. Diagram showing the relationship between sintered ore particle size and inert zone thickness at the lower berry stage (furnace upper part).
FIG. 5 is a diagram showing the relationship between the coke particle size in the Bosch part and the thickness of the inert zone in the Bosch part (furnace middle), and FIG. 6 is a diagram showing the transition of blast furnace operation in an embodiment of the present invention. Figure 4 Figure 5 Bosch section Cork 3 diameter (IIB)

Claims (1)

[Claims] The particle size of charging raw materials such as sintered ore and coke in the furnace is estimated using a charge property deterioration model, and the physical property values calculated from the estimated particle size in the furnace are set as control standard values, and based on the control standard values. 1. A method of operating a blast furnace, characterized in that the charged raw materials are managed in accordance with blast furnace operating conditions, and the charged raw materials are selectively used according to blast furnace operating conditions.