JPH044364B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a blast furnace blowdown operation method that allows easy treatment of residual pig iron during blowdown operation of a blast furnace.

<Prior Art> Generally, when a blast furnace is repaired in a short period of time, it is required to shorten the period for dismantling the residual pig iron after blowdown operation. Therefore, conventionally, as shown in Fig. 2, a residual pig iron blowing port 4 is provided at the end of blowdown to discharge the residual pig iron 2.
In this method, the entire amount cannot be removed and remains in the hearth and solidifies. The solidified residual pig iron is then crushed using a crusher such as a breaker or dynamite, and an opening 6 in the steel shell is provided, through which the solid residue is discharged.

However, with the conventional methods mentioned above, disassembly and
In class 3 blast furnaces with an internal volume of 2,000 m ³ to 4,000 ^{m 3} , it takes about 10 days or more to discharge the waste, which is a factor that hinders the shortening of renovation time.

Therefore, in Japanese Patent Application Laid-open No. 57-104605,
It has also been proposed to drill a horizontal hole just below the eroded surface of the furnace bottom, raise the pressure inside the furnace higher than the pressure outside the furnace, and discharge it by communicating with the joint cut part of the furnace bottom brick. Since there is a solidified layer of hot metal in contact with the hearth bricks, there is a problem that it cannot be put to practical use. Even if a solidified layer does not exist locally, it does not necessarily mean that the bricks are damaged and the joints are broken, and the gaps may be narrow, causing blockages and making it impossible to discharge. , also from this point of view, there is a problem that it is not practical. Under these circumstances, despite the need to further shorten the dismantling and discharge period, the reality is that there is still no fundamental solution.

<Problems to be Solved by the Invention> As mentioned above, the conventional method had the problem that it took a long time to dismantle and discharge the residual pig iron after blowdown. This was done in order to provide a method for operating blast furnace blowdown operations that can be done in a short amount of time.

<Means for solving the problem> As a result of intensive research into a method for smoothly and quickly discharging the residual pig iron at the bottom of the hearth after blowdown, the present inventors discovered the basic knowledge that FeMn pig iron is brittle. Originally, instead of charging iron ore at the end of blowdown, manganese ore was charged to generate and solidify FeMn pig iron, which is highly brittle, in the hearth. This makes crushing easier and shortens the period for dismantling and discharging residual pig iron.

The present invention involves charging manganese ore instead of iron ore at the end of the blast furnace blowdown operation.
This is a blowdown operation method characterized by producing and solidifying FeMn pig iron in the hearth.

<Function> In making the present invention, several types of FeMn with different Mn% were generated and studied in advance, and as a result, the Mn%
It was found that when the amount of damage increases, it can be easily destroyed by applying a light impact force.

Therefore, in the present invention, an operation was carried out in which manganese ore was gradually charged in place of iron ore during the operation before coke replacement at the end of blowdown operation. As a result, the residual pig iron solidifies when it contains 50% or more of Mn.
FeMn was formed and became brittle, causing cracks to occur on the surface and making it easier to disassemble.

<Example> As shown in Figure 1 in a blast furnace with an internal volume of 3000 ^m3 , after the wind reduction started, a transition operation to FeMn pig was carried out, and when the Mn% of FeMn pig reached 60% or more, ore loading was carried out. The air supply was stopped and the furnace was blown down by coke replacement.

After the above-mentioned blowdown operation, the residual pig iron was crushed using a breaker and then discharged from the shell opening using a shovel car. The dismantling and discharge process, which conventionally took more than 10 days, was completed in about 3 days. I was able to finish it.

Note that the discharged FeMn is supplied and used as a Mn source in the next step of converter refining.

<Effects of the Invention> As described above, according to the present invention, solidified
Since FeMn pig iron is highly brittle, it can be easily crushed and discharged, so the time required for dismantling the hearth bottom, which used to take more than 10 days, can now be reduced to one third.

Furthermore, the discharged FeMn pig iron can be supplied and used as an auxiliary raw material for steelmaking, which has the effect of enabling inexpensive steel refining.

[Brief explanation of drawings]

FIG. 1 is a graph showing an example of a blowdown operation according to the method of the present invention, and FIG. 2 is an explanatory diagram showing an example of a conventional iron residue removal operation. 1... Blast furnace, 2... Residue, 3... Tap hole, 4...
...Residue extraction port, 5...Residue extraction gutter, 6...Steel skin opening.

Claims (1)

[Claims] 1. A blast furnace blowdown operation method characterized in that, in the blast furnace blowdown operation, manganese ore is charged in place of iron ore at the end of the blast furnace to form and solidify FeMn pig in the hearth.