JP3682267B2 - Residue reduction method during blast furnace renovation - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a residue reduction method for reducing the amount of hot metal remaining in a furnace bottom when a blast furnace is blown off and repaired.
[0002]
[Prior art]
Since refractories and cooling equipment installed in the blast furnace deteriorate and break down during operation, it is necessary to periodically repair and replace them. Such renovation work is a large-scale work performed by blowing off the blast furnace. In addition, it is necessary to discharge the residue outside the furnace prior to the renovation work.
In the conventional blast furnace refurbishment, there is a method for providing a waste recovery outlet below the normal outlet, and discharging the hot metal from the residue recovery outlet to the outside of the furnace. Was taken.
[0003]
In such a hot metal recovery method, a furnace bottom discharge iron was provided, and the discharged hot metal was received by a torpedo car.
Moreover, when the height between the furnace bottom and the orbit of the torpedo car is insufficient, the torpedo car cannot be used. Therefore, a method of discharging hot metal to a slag pit or the like has been adopted.
[0004]
[Problems to be solved by the invention]
However, in the conventional residue collection method described above, when installing the dredger for the bottom out of the furnace, there are many facilities that cannot be removed immediately above the place where the dredger should be installed. However, it was difficult to set up the coffin because it was a hindrance.
Also, in the method of discharging hot metal using slag pits, etc., the slag pits must be cleaned up after the hot metal discharge, but this slag pit cleaning work interferes with the lifting equipment installation work and the iron skin dismantling work. There was a problem that the construction period was prolonged.
[0005]
In addition, it is necessary to newly install a residue collection outlet and a furnace bottom outlet, resulting in increased equipment costs.
Therefore, as previously proposed in Japanese Patent Application No. 11-21059, it has been proposed to reduce the residue by loading a load filler.
However, this method can reduce the residue, but when the renovation is carried out, the coke remaining near the tuyere burns and rises as high-temperature gas. May be melted.
The present invention has been proposed in view of the above-described circumstances, and when the blast furnace is blown off and repaired, the amount of residue in the furnace is reduced, the repair work period is shortened, and the repair cost can be reduced. The aim is to provide a possible method for reducing residues.
[0006]
[Means for Solving the Problems]
The method for reducing residues at the time of blast furnace refurbishment according to the present invention is to reduce the charge when blowing the blast furnace for refurbishment, and when the stock level drops to the upper tuyere, the additional coke is charged. Subsequently, by loading a high-specific gravity load filler such as silica or iron ore, the core coke is allowed to settle in the hot metal while the molten iron is discharged while the molten iron is discharged. It is characterized by reducing the amount of lump.
[0007]
When such a method is used, the furnace core coke settles in the hot metal and mixes with the hot metal by the load of the coke additionally charged from the upper part of the furnace and the load for loading. And, by increasing the layer of this mixture to the vicinity of the bottom of the furnace, the amount of hot metal remaining in the furnace is reduced, and the layer of residual lump that is difficult to break down is reduced, so the repair period of the blast furnace can be shortened. .
When the additional coke is charged when the stock level drops to the upper part of the tuyere, the additional coke is charged around the tuyere and around the furnace. In this state, when loading with a high specific gravity load such as silica or iron ore, silica and iron ore are charged with the additional coke around the tuyere and around the furnace. It is cooled by the endothermic reaction with coke, etc., and the silica does not reach the residue directly, it can be prevented from melting, and it can be used as a filling material for load. .
Therefore, the additional coke is preferably charged on the furnace wall side.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a method for reducing residue at the time of blast furnace repair according to the present invention will be described with reference to the drawings. 1, 2 and 3 are explanatory views for explaining a method for reducing residues at the time of blast furnace repair according to the present invention.
At the time of blast furnace operation, as shown in FIG. 3, the hot metal 2, the core coke and hot metal or slag mixture 3, and the furnace core coke 4 exist in layers from the bottom to the top in the blast furnace 1. ing. On top of that, a lump 10 which is the uppermost solid ore and coke area, a cohesive zone 11 where the semi-molten ore and coke are present, and the coke moves toward the raceway 12. The ore forms a dripping zone 13 in a region where the ore becomes hot metal / slag and drops downward. Further, a tuyere 5 and a tap 6 are provided on the side of the blast furnace 1.
During operation of the blast furnace, the core coke 4 is lighter than hot metal and slag, and thus receives buoyancy, but sinks considerably below the liquid level due to the load of the charge. However, when the blast furnace 1 is blown off and repaired, if the charge reduction operation is performed to the vicinity of the tuyere level, the load on the charge disappears. As shown in FIG. It floats up to just below the surface level, and the molten iron 2 existing at the bottom of the furnace greatly increases, and after blowing off, it cools and hardens to form a large amount of residual iron. If the furnace diameter of the blast furnace 1 is assumed to be about 14 m, about 1000 tons of residual residue in the furnace will remain, and it is very difficult to destroy the residual residue in the furnace. End up.
[0009]
Therefore, in the method for reducing residues at the time of blast furnace repair according to the present invention, as shown in FIG. 1, when the blast furnace is blown off and repaired, the charge is reduced, and the stock level decreases to the upper part of the tuyere. At that time, the additional coke 7 is charged from the upper part of the blast furnace 1 around the furnace peripheral part of the blast furnace 1. The additional coke 7 is charged in an amount sufficient to cool the high-temperature gas generated by burning the coke at the tuyere.
[0010]
Here, as a comparison with the use of silica or iron ore as additional coke 7 and additional filler 8 for additional charging,
Coke has a bulk density of 0.5 t / m ³ , while quartzite has 1.6 t / m ³ and bulk ore has 2.5 t / m ³ . However, when quartzite or lump ore dissolves, it becomes slag or slag and pig iron, respectively.
Accordingly, since the coke is not high in bulk density, the effect of settling the core coke 4 is smaller than that of silica or iron ore. However, if the upper part of the core coke 4 is covered with the additional coke 7, the tip of the tuyere By working as a coolant through an endothermic reaction or the like without melting with respect to the high temperature gas generated from the gas, the temperature of the gas passing therethrough and the upper portion of the coke can be lowered.
[0011]
Therefore, following the charging of the additional coke 7, a loading material 8 such as silica or iron ore is charged on the additional coke 7 continuously from the top of the blast furnace 1.
As this packing material 8 for load, silica stone and lump ore have a large bulk density as described above, and when loaded on coke, they are not dissolved and a significant increase in load can be expected. As described above, when it is assumed that about 1000 t of residual residue in the furnace remains, a vertical load of about 500 t is required to form the mixture 3 layer up to the bottom of the furnace. Can be obtained, and the core coke can be surely settled, and the in-furnace residual lump remaining in the furnace can be further reduced.
[0012]
In addition, although the mixture 3 of the core coke 4 and the hot metal 2 located below the tap outlet 6 cannot be discharged, the mixture 3 can be easily broken as compared with the residual residue in the furnace. Therefore, the burden on the renovation work is much smaller than the case where the residual lump remains.
[0013]
[Example]
When the reduced level blowing operation was performed in a blast furnace with a hearth diameter of 10.7 m and the stock level dropped to the upper part of the tuyere, 160 t of additional coke 7 was charged in the periphery of the blast furnace, and then 400 t of silica stone. Was loaded. With this additional load, 200 t of molten iron was discharged out of the furnace. If the coke porosity of the mixed layer is 0.4, the remaining iron displaced by the settled coke is 200 t, so the remaining iron layer 330 t (= 200 / (1-0.4)) is the coke and the remaining iron 130 t. That is, the remaining iron ingot of 330 t could be reduced.
In addition, as a comparative example, when a reduced-scale blow-off operation was performed in a blast furnace with a hearth diameter of 12.5 m and the stock level decreased to the upper part of the tuyere, when 950 t of silica was charged into the blast furnace, Although about 200 tons melted and 260 tons of remaining iron was discharged and about 430 tons of remaining iron ingots could be reduced, the effective load with respect to the added additional load, that is, the ratio that was effective in discharging molten iron was small. This was because about 200 t of the silica stone charged as an additional load melted and did not work as a load.
[0014]
【The invention's effect】
According to the residue reducing method at the time of blast furnace repair according to the present invention, the core coke is settled in the hot metal by the load of the additional charge, and the mixture layer is increased.
For this reason, the amount of the hot metal remaining in the furnace decreases, and the layer of the residual lump that is difficult to break down decreases. Further, since the mixture of the furnace core coke and hot metal is more easily broken than the residue lump, some mixture may remain in the furnace.
Therefore, it is no longer necessary to destroy the lump, and the repair period of the blast furnace can be shortened. In addition, since there is no need to newly install a residue collection outlet and a furnace bottom outlet, the facility cost can be reduced.
[0015]
And, by charging the coke prior to charging the load filler, it is possible to prevent melting of the load filler silica or iron ore, and to ensure that the core coke settles in the hot metal. Can be reduced, and repair work can be reduced.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram for explaining a method for reducing residues at the time of blast furnace repair according to the present invention. FIG. 2 is an explanatory diagram for explaining a method for reducing residues at a blast furnace repair according to the present invention. Schematic diagram of the inside of the blast furnace during operation [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Blast furnace 2 Hot metal 3 Mixture 4 Furnace core coke 5 tuyere 6 Outlet 7 Additional coke 8 Load filling 10 Lump 11 Fusion zone 12 Raceway 13 Submerged zone

Claims (2)

When the blast furnace is blown off and renovated, the charge is reduced and additional coke is charged when the stock level drops to the upper tuyere, followed by high loads such as silica and iron ore. At the time of blast furnace refurbishment, which reduces the amount of residual litter by charging the core coke into molten iron and discharging molten iron while preventing the melting of silica and iron ore by charging the filler. How to reduce the residuals. The method of claim 1, wherein the additional coke is charged to a furnace wall side.

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