JPS609806A - Operating method of blast furnace by which powder is blown through tuyere - Google Patents

Abstract

PURPOSE:To maintain the uniform characteristics of molten irons and to meet the requirement for small-volume production of diversified kinds with a method for blowing various kinds of powders through each tuyere into a blast furnace by controlling the blowing of the powder according to the characteristic of the molten metal from each tap hole. CONSTITUTION:The characteristics, such as the temp. and components, of the molten iron to be tapped from each tap hole are measured with a method for operating a blast furnace provided with plural tap holes in the circumferential direction thereof while blowing various kinds of powders through each tuyere into the furnace. The kind and amt. of powder to be blown through the tuyeres in the range having relation corresponding to the respective tap holes are controlled according to the results of the measurement so that the molten metal to be tapped from each tap hole have uniform characteristics. Or the kind and amt. of the powder to be blown through the tuyere within the range having the relation corresponding to the specific tap hole are preliminarily controlled so that the molten iron having the required characteristics can be tapped from the specific tap hole according to the results of the above-described measurement.

Description

[Detailed Description of the Invention] Technical Field The present invention is directed to blowing pulverized coal, pulverized limestone, etc. into the blast furnace together with blast air through the lining of the blast furnace, reducing costs, stabilizing the furnace condition, and further improving the properties of the molten material. This relates to the operation of a blast furnace that aims to achieve this goal.

BACKGROUND OF THE INVENTION Conventional blast furnaces usually have two to four tap holes, and the common operating mode is to open these ports alternately for tapping. In blast furnaces, efforts are made to make the conditions uniform at each location along the furnace periphery so that there is no deviation in hot metal composition, temperature, etc. between these tap ports, but the top charging equipment, ore, Imbalance of material accumulation in various parts along the furnace circumferential direction (hereinafter referred to as the furnace circumferential direction) when charging raw materials such as coke, unbalance of gas flow in the furnace circumferential direction due to unresponsiveness of bricks in the furnace, and occurrence of damage. For example, unevenness may occur in hot metal fA degree, SIaO, Ti, 8%, slag basicity (/8□.2), etc. between each tap hole. Nak 1 taphole
・・Hot metal temperature: 1520℃, Si: O, fiOa
O-related, Ti: 0.08%, /Sio2: 1.26
, S: 0.035cm, No. 2 taphole...Hot metal temperature: 1480℃, Si:
0.380a, 0 Ti: 0.04%, /sio,: 1. ]
, 4, S: O, 0Fi2ch, etc. Such a force difference not only causes the quality of blast furnace hot metal to be out of specification, but also poses a major hindrance to the next step of steelmaking process work. Moreover, from the viewpoint of safety in blast furnace operation, furnace thermal action is taken based on the lower temperature of hot metal, etc., so there has been a tendency to inevitably increase the fuel ratio.

On the other hand, recently, reflecting the diversification of the steelmaking sector, the demand for hot metal has become extremely low, such as 8% hot metal or a small amount of high T1 pig iron (50%).
ot/aay), etc., and it has been difficult to respond quickly to these developments.

OBJECTIVES AND SUMMARY OF THE INVENTION An object of the present invention is to control the injection of powder into the tuyeres so that the properties of hot metal are uniform between the plurality of tap holes in the circumferential direction of the furnace, thereby improving the operation in subsequent processes. In addition, the injection of powder into the siding is adjusted so that a small amount of molten pig iron with the desired composition and temperature is tapped from a specific tap hole, making it possible to meet the needs of a wide variety of products in small quantities. The object of the present invention is to overcome the drawbacks of the prior art described above. To this end, the present invention provides a method for operating a blast furnace provided with a plurality of tap holes in the circumferential direction while injecting various types of powder through each wall. The temperature and component properties of the hot metal tapped from each tap are measured, and according to the measurement results, each tap is adjusted so that the hot metal tapped from each tap has uniform properties in the direction of the furnace circumference. a method for controlling the type and amount of powder blown into a tuyere within a corresponding relationship with the pigtail;
and (8) Second, measure the temperature and component properties of the hot metal tapped from each of the above-mentioned tapholes, and according to the measurement results, the hot metal with the required properties is extracted from the specific taphole. The above technical problem has been solved by a method of controlling the type and amount of powder injected into the tuyere within a range corresponding to a specific tap hole in advance so that the iron can be tapped.

Structure of the Invention Fig. 1 is a wiring diagram of a typical taphole (A I THNA4 TH) in a 4500 m2 blast furnace.
A combination of either one of these is used.

FIG. 2 is a system diagram of a device for blowing powder into a tuyere used to carry out the present invention, in which 1 is a blast furnace, 2 is a tuyere, 8 is a powder storage tank, 4 is a pressure equalization tank, and 5 is a This is a tank for transportation, and the amount of blowing can be adjusted for each tuyere 2.

The present invention aims to improve powder production in the direction of intensively correcting the tap hole, which has a large difference compared to other locations, so that hot metal with uniform properties can be tapped from the Nn1-4 TH tap hole. This is a method of blowing, and a method of locally changing and adjusting the hearth sump in a specific direction, the components of the hot metal slag, etc.

For example, in the former method, m
When taking action at 1TH, the required powder is blown in the required amount from a total of 8 tuyeres 2a (out of 40 tuyeres all around), 4 digits located on both sides. for example,
This is the case when pulverized coal is injected through the tuyere 2a to raise the furnace heat in that part and push up the hot metal temperature, thereby eliminating the difference in hot metal temperature between days of tapping.

As a specific example of the latter, in order to tap a specific (N111TH) taphole with extremely low S pig iron, the taphole (1mlT
In this method, fine limestone is injected from the tuyere 2a in the range that affects H), and low S pig iron is obtained only from the Mal tap hole. In this case, the required amount is the amount of tapped iron (450
If it exceeds 800 t/times at 0m8:lq degrees,
The limestone injection operation can be continued as is.

Example (1) Eliminate the difference in tap days by uniformizing the hot metal temperature that differs significantly between the tapholes. 5.1 shows the change in hot metal temperature when K9/l-p is injected. In the figure, period 1 is without blowing, period ■ is with injection of 5 KP/, and period IIT is injection with l OKQ/. Yes, but 1
In the period, IJn I TI (, 8TH hot metal temperature difference (ΔT
) was approximately 28°C, but in the ■ period it was 12°C, and in the ■ period the temperature was finally reversed, with the hot metal temperature increasing by 2°C in the 8TH period. The relationship between the amount of pulverized coal injected and the hot metal temperature is not uniform, and is thought to vary greatly depending on the mixed state of coke ore in the upper part of the furnace and the mixed state of hot metal slag in the hearth. It can be seen that charcoal injection technology can be used as a means to eliminate temperature differences in hot metal.

In addition, the coke replacement rate during injection (ratio between the amount of pulverized coal injected from the tuyere and the coke charged from the upper part of the furnace) is O,
S was 0 (2) - Operation example for tapping extremely low S rust from the tap hole; In a blast furnace with a tapping rate of 8000 t/cl, Nu 8 TH
An example of when 20 kg/l-p of limestone is injected near the outlet is shown in Figure 5.The basicity of blast furnace slag during normal operation is about 1.10 to 1.15. Against Nl
When limestone is injected through 8 tuyeres corresponding to 18 TH, the increase is 1.25 to 1.80-i, and the upper limit of (S%) in the pig iron is 0.04%-0 accordingly. It can be seen that the S content has significantly decreased to 0.3%.0 As described above, according to the present invention, it is possible to produce extremely low S pig iron that meets the short-term demand of downstream processes.0 Detailed Description of the Invention As described above, according to the present invention, by controlling the powder injection from the tuyeres, it is possible to make the different properties of hot metal between the tapholes uniform, and conversely, it is possible to make the properties of hot metal that differ between the tapholes uniform. It is possible to tap hot metal with desired composition and temperature.
As a result, it is possible to reduce costs due to low fuel ratio operation, and improve the efficiency of post-processes by immediately responding to the needs of steel manufacturers (7) for high-product, low-volume production.

[Brief explanation of drawings]

Figure 1 is a route map showing an example of the blast furnace taphole arrangement, Figure 2 is a route map showing the powder flow of the powder injection device, and Figure f48 is a route map showing an example of the blast furnace tuyere arrangement. , Fig. 4 is a graph showing the change in hot metal temperature during pulverized coal injection operation, and Fig. 5 is a graph showing the relationship between pig iron (S%) and slag basicity during limestone injection operation. Patent applicant: Kawasaki Steel Corporation (8) NO, 37H No, 2nd H

Claims (1)

[Scope of Claims] 1. A method in which various powders are injected through each tuyere into a blast furnace equipped with a plurality of tap holes in the circumferential direction of the furnace, in which the iron is tapped from each of the tap holes. Measure the hot metal temperature, components, and other hot metal properties, and according to the measurement results, make sure that the hot metal tapped from each tap hole has uniform properties in the circumferential direction of the furnace.
A blast furnace operating method in which powder is injected through tuyeres, characterized by controlling the type and amount of powder injected into the tuyere within a range corresponding to each taphole. a. In a method in which various powders are injected through each tuyere into a blast furnace equipped with multiple tap holes in the circumferential direction of the furnace, the temperature, composition, etc. of the hot metal tapped from each of the tap holes described above. The properties of the hot metal are measured, and according to the measurement results, the tuyeres within the range corresponding to the taphole are injected in advance so that the hot metal with the desired properties can be tapped from a specific taphole. A blast furnace operation method in which powder is injected through a tuyere, which is characterized by controlling the type and amount of powder to be injected.