JPH01234510A - Method for starting reblowing in dead blast furnace - Google Patents

Abstract

PURPOSE:To smoothen start of reblowing dead blast furnace by replacing the min. limit quantity of residual material at front of tuyere and iron tapping hole into the new coke after repairing the blast furnace by lowering stock level to the tuyere level and stopping blowing. CONSTITUTION:After lowering the stock level to the tuyere 3 level, the blowing is stopped. The upper part of the furnace is repaired as remaining the charging material below the tuyere 3 in the blast furnace, in which the blowing is stopped. Successively, after completing this repair, only flowing passage of molten iron and slag at the front of the tuyere 3 and the charging material in the furnace at stored iron and slag zone at the front of the iron tapping hole 2 are replaced with the new coke 4. Further, a pipe is inserted into the further through the above iron tapping hole 2. Then, oxygen is blown into the furnace through the pipe 5 and successively, the reblowing is executed from the tuyere 3.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for restarting a dormant blast furnace for re-blowing.

(b) Conventional technology Blast furnaces are closed off approximately 6 to 8 years after being fired, and reheated after repairs to the furnace walls, bottom, etc. are performed. When stopping the blowout, it is common to reduce the length to the tuyere level and then stop the blowout, in order to reduce the work required to discharge the residue inside the furnace after the blowout has been stopped.

As shown in FIG. 5, unburned coke, pig iron, and pig slag remain in the furnace at the time of stopping. After the blow-off,
It is common to carry out work to discharge these residues and then carry out repair work. The renovation work included relining the furnace walls,
After the hearth bricks are transferred and sleepers are piled up to the tuyere level as shown in Figure 6, the furnace is filled with ore and coke and reheated.

Most of the factors that determine the life of a blast furnace are damage to the furnace wall. Two generations of hearth bricks can be used. However, in the conventional method of discharging residual coke residue in the furnace,
Because water flooded the bottom bricks when the residue was being submerged and cooled, some or all of the bottom bricks were transshipped during the renovation, and a new one was also transshipped. In order to prevent damage due to force spalling, it was necessary to suppress the rate of increase in load during start-up operation.

Furthermore, when it is necessary to suspend a blast furnace for a long period of time due to reasons such as adjusting production volume, it is necessary to carry out renovation works such as removing residual material from the furnace.

(c) Problems to be Solved by the Invention The problem to be solved by the present invention is to obtain a method that can smoothly carry out interim repairs of a blast furnace or restarting of air blowing after a long-term suspension.

(d) Means for Solving the Problems The method for restarting a suspended blast furnace according to the present invention is to move the blast furnace, which has been reduced in length down to the tuyere level, into the upper part of the blast furnace while leaving the contents of the furnace below the tuyeres. Repairing the furnace body, replacing only the contents of the furnace in the hot metal slag flow path in front of the tuyere and the pig iron slag storage area in front of the taphole with new coke, and inserting a pipe into the furnace through the taphole. The above problem is solved by means of blowing oxygen into the furnace from there and reblowing air from the tuyeres.

The method of the present invention can also be applied when the blast furnace is shut down for repairs after its length is reduced, and then the blast furnace is stopped for repairs and restarted for air blowing.

(E) Example The method of the present invention makes it possible to start up the blast furnace by reheating it while leaving the residue inside the furnace, so there is no need for intermediate renovation or renovation work that leaves the bottom bricks in place. Allows for long periods of rest.

Therefore, when renovating the space where the bottom bricks remain and the upper furnace wall, the first thing to do is to assemble construction scaffolding, clear the access for workers, and remove the residual coke above the tuyere level, as shown in Figure 1. It is necessary to drain it and seal it with concrete or the like.

As a method for restarting air blowing after renovation in such a state, the method of the present invention removes residual coke in front of the taphole 2 and tuyere 3, as shown in FIGS. 2 and 3. Dig up the chisel and replace it with new coke 4. FIG. 2 is a longitudinal sectional view thereof, and FIG. 3 is a horizontal sectional view thereof. Hot metal and pig iron slag at the beginning of start-up operations are at low temperatures and have poor fluidity. In addition, residual coke during blow-off operation is burned during blow-off operation, resulting in a decrease in strength and a drop in particle size, resulting in poor liquid permeability. If the coke is not replaced, it will be difficult to discharge the hot metal and pig iron slag that are generated in front of the tuyere from the taphole, making it difficult to start up smoothly after reheating.

In addition, even in the case of reheating after a long pause without repair work, as shown in Figure 4, by replacing the residual coke in front of the tuyere 3 and in front of the tap hole 2, smooth start-up can be achieved. Realized.

However, if the replaced coke comes into contact with hot metal or pig iron slag at the time of start-up, it may cool and solidify. Oxygen is blown into the furnace, and then the tuyere 3
Vent the air again.

Table 1 shows the results of partial replacement of residual coke and startup of reheating using the method of the present invention in a blast furnace with a content Wt of 2100 m3. Compared to reheating and startup using conventional methods,
A single line with a significant period of return to original specifications was realized.

Table 1 (Each specification is the number of days until return.) (to) Effect According to the method of the present invention, the following effects can be obtained.

Construction costs are reduced because the minimum amount of residue in front of the tuyere and taphole is replaced.

ii. In order to raise the temperature of the contents of the furnace, the tap hole is usually opened with a hole rod, a pipe is inserted, and oxygen is blown into the tap hole, which is a very simple method, which eliminates the need for almost all the equipment, equipment, and construction costs.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram at the time of repairing the upper furnace-6 = body, which is the initial step of the method of the present invention. FIG. 2 is an explanatory diagram of an intermediate step of the method of the present invention. Figure 3 shows m''#r# seen from the ■-■ line in Figure 2.
The r-view diagram is an explanatory diagram when the method of the present invention is applied to a blast furnace after a long-term suspension. FIG. 5 and FIG. 6 are explanatory diagrams of the conventional method. 1: Concrete seal 2: Tap hole 3: Tuyere
4: New coke 5: Pipe patent applicant Sumitomo Metal Industries, Ltd.

Claims (2)

[Claims] (1) Repairing the upper furnace body of a blast furnace that has been reduced in length to the tuyere level while leaving the contents of the furnace below the tuyere; Shutdown consists of replacing only the contents of the furnace in the slag storage area in front of the tap with fresh coke, inserting a pipe into the furnace through the taphole and blowing oxygen into the furnace from there, and re-blowing air from the tuyere. How to start up blast furnace re-blowing. (2) Shut down the blast furnace that has been cut down to the tuyere level, and only replace the furnace contents in the hot metal slag flow path in front of the tuyere and the pig iron slag storage area in front of the taphole after shutting down. A method for restarting a dormant blast furnace by replacing it with coke, inserting a pipe into the furnace through the taphole and blowing oxygen into the furnace from there, and reblowing air from the tuyere.