JPH0559459A - Manufacture of sintered ore - Google Patents

Abstract

PURPOSE:To prevent the reduction in a yield with a simple method and to improve the productivity by supplying additive mixed in suction air on a sintered layer in the latter half of sintering process at the time of manufacturing sintered ores in a downward suction type sintering machine. CONSTITUTION:From hoppers 9-6, ore, lime stone, returned ore and coke are discharged, respectively, and humidity conditioning and granulation are executed with a mixer 10. This sintering raw material is charged pallets 12 from a drum feeder 3 through a chute 4 to form the packing layer 5, and coke on the surface of the layer 5 is ignited with an ignition furnace 11. The additive 32 is once stored into a storing hopper 33 and discharged by the prescribed quantity with a belt feeder 31 and carried to a hood 21 with a belt conveyor 34 and dropped and supplied onto the surface layer of the sintering layer while uniformly dispersing with rotated dispersing blades 22 in the hood. This additive is shifted with the air sucked downward in crack on the surface layer of the sintering layer and crack on the inner wall of the pallet and reaches a high temp. zone during progressing of the sintering, the cracks are closed under melting, semi-melting or shape-holding condition. Therefore, gas permeability in the sintering layer is uniformized and stable sintering can be executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a sintered ore which is a raw material for producing pig iron in a blast furnace or the like. According to the present invention, the productivity in the production of sinter can be greatly improved.

[0002]

2. Description of the Related Art Iron ore is a main raw material for the production of sinter, and limestone as an auxiliary raw material, coke as a fuel, and the like are mixed with a mixer and subjected to humidity conditioning granulation. The sintering raw material is conveyed to a sintering machine and charged to form a sintering raw material packed layer. In the case of a sintering process using iron ore as a main raw material, the thickness of the raw material packed layer is usually about 600 mm. The coke on the surface layer of the packed bed is ignited in an ignition furnace to burn the coke while sucking air from below, and the combustion heat sinters the raw materials sequentially from the upper layer to the lower layer.

FIG. 2 is a plan view of the surface layer of the sintered layer after it has come out of the ignition furnace 11 as seen from above in the conventional method. Ignition furnace 1
Sintered surface layer cracks 42 are irregularly generated on the sintered layer surface layer 41 after exiting from No. 1, and these cracks 42 grow due to compaction until discharged and become large cracks. Such cracks have less ventilation resistance than a crack-free sintered layer, a large amount of suction air flows to increase the sintering rate, and they are cooled rapidly so that they are not sufficiently sintered. It becomes a sintered ore with low strength. For this reason, there is a problem that fine particles are increased during crushing and sizing, and the yield (yield) of products with a size of 5 mm or more decreases.

On the other hand, since the crack-free sintered layer has a higher ventilation resistance than the cracked portion, the supply of suction air is reduced and the sintering time becomes longer. Since the time for forming the crack-free sintered layer is the sintering time, the sintering time becomes long, and as a result, the decrease in yield due to the reasons described above and the decrease in productivity due to the extension of the sintering time are major problems. Becomes

Further, the portion of the pallet inner wall crack 43 existing near the inner wall of the pallet side plate also has a smaller ventilation resistance than the crack-free sintered layer in the central portion of the pallet, and a large amount of sucked air flows to increase the sintering rate. Since it is cooled rapidly, it is not sufficiently sintered, and the product obtained here is a sinter having low strength. For this reason, there is a problem in that, like the portion of the sintered surface layer crack 42, fine particles increase during crushing and sizing, and the yield decreases.

As a method for solving such a problem, Japanese Patent Laid-Open No. 61-48537 discloses a method of placing a raw material on a crack portion generated in the surface layer of a sintered layer and filling the crack. However, with this method, it is difficult to fill and fill the raw material without leaking only into the cracks that occur irregularly, and the raw material is also placed in the crack-free sintered layer, which impedes ventilation and has not been put to practical use. Is the current situation.

The inventors of the present invention also provided protrusions on the pallet traveling rails to generate small cracks dispersed on the surface of the sintered layer.
We have applied for a patent for a method to mitigate the adverse effects of large cracks. However, even with this method, the decrease in yield and the decrease in productivity have not been completely solved, and crack countermeasures are desired.

[0008]

SUMMARY OF THE INVENTION The present invention solves the problem of reduced yield or reduced productivity caused by the generation of cracks 42 on the surface of the sinter layer or cracks 43 on the inner wall of the pallet. It is an object of the present invention to provide a sintering method capable of significantly improving the temperature.

[0009]

The feature of the present invention resides in that, when a sintered ore is manufactured using a downward suction type sintering machine, after the sintering raw material packed bed is ignited, the sintering is in progress. In addition, in the latter half of the sintering process in which cracks occur in the surface layer of the sintered layer and grows, an additive for closing the cracks is mixed into suction air, and the additive is supplied to the sintered layer in which cracks grow. To do. In particular, as an additive for closing cracks, use one of limestone, silica stone, blast-furnace slag, steelmaking slag, dust collected in ironworks, and fine iron ore, or use a mixture of two or more thereof. Is characterized by.

[0010]

The present inventors have been studying the countermeasure against the adverse effect of a large crack that irregularly occurs on the surface of the sintered layer and grows due to compaction until it is discharged. The additive for closing the crack is supplied to the crack, and it reaches a high temperature zone of the sintering progressing part at the crack tip, but the timing of arrival may be slightly different, but from the molten state to the semi-molten state, or even the crack additive as it is. It was found that the crack can be closed under the condition of. Since the crack has a small ventilation resistance, a large amount of suction air flows, so that the additive for closing the crack is selectively sucked into the crack together with the suction air.

When the crack is closed, the ventilation resistance of the crack is increased and the amount of sucked air is reduced. Therefore, the suction negative pressure is uniformly applied to the entire sintered layer, and the progress of sintering of the entire sintered layer is uniform and accelerated. Therefore, the productivity is improved by improving the yield and shortening the sintering time.

The additive for closing the crack is not particularly limited. A considerable amount of the supplied crack additive is discharged to the smelting section in the initial state without being in a molten or semi-molten state, and is returned to the sintering raw material together with the returned ore that is not recovered as a product. Therefore, a fine-grained substance that can be used as it is as a sintering raw material is preferable. Therefore, limestone, silica stone, blast furnace slag, steelmaking slag, dust collecting dust in ironworks, and fine ore are suitable as additives for closing cracks. Also, if the particle size of this crack additive is too large, it will not be sucked into the crack, so 3 mm or less,
It is preferably 0.5 mm or less.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to FIG. 1, which is a preferred embodiment. In FIG. 1, the sintering raw material is
Ore hopper 9, limestone hopper 8, return ore hopper 7,
Ore, limestone, return ore, and coke were each cut out from the coke hopper 6, subjected to humidity conditioning granulation by the mixer 10, and the packing layer 5 was formed on the pallet 12 from the drum feeder 3 through the chute 4. Thus, the surface coke of the packed bed 5 formed by the same process as the conventional method was ignited in the ignition furnace 11. The additive 32 for closing the crack was temporarily stored in the crack additive storage hopper 33, cut out by the belt feeder 31 by a predetermined amount, and conveyed to the hood 21 by the belt conveyor 34. The crack additive is dropped and supplied to the surface layer of the sintered layer while being uniformly dispersed by a dispersion rotary blade 22 in a hood which is rotated by a motor (not shown) via a driving device. Thus, the crack additive supplied to the surface layer of the sintered layer is
Air moves downward in the cracks in the sintered surface layer and in the cracks on the inner wall of the pallet, and reaches the high temperature zone during the progress of sintering to close the cracks in a molten, semi-molten or tangible state.

Table 1 shows the suction conditions in the examples.

[Table 1]

The cracking additives are limestone, silica stone, blast furnace slag, steelmaking slag, dust collected in ironworks (blast furnace ash, sintered dust collected), and fine iron ore. The powder supply amount of these crack additives to the sucked air is 1 pallet (area 7.5).
The range is 10 to 80 kg per square meter. 80
If it exceeds kg, ventilation of the crack-free sintered layer is hindered, which is not preferable. The position of the crack additive supply in the sintering machine is
It may be a part of the latter half of the sintering, and although it varies to some extent depending on the sintering machine, the position where the cracks that start to grow start, that is, the beginning of the latter half of the sintering is preferable.

According to the invention, the productivity of the conventional method 32.2.
As shown in Table 1, the productivity was improved to 37.5 to 40.1 (t / d / square meter) with respect to (t / d / square meter).

[0017]

According to the present invention, by supplying the crack additive at the time when the crack grows during sintering, the crack can be selectively sucked into the crack portion having a small suction resistance to close the crack portion. This prevents the occurrence of uneven sintering,
Yield improvement can be achieved.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a sintering process for carrying out the present invention.

FIG. 2 is a diagram showing a state of cracks generated in a sintered layer of a conventional method.

Claims (2)

[Claims] 1. When producing a sintered ore using a downward suction type sintering machine, after igniting a sintering raw material packed layer, sintering is in progress and cracks occur in the surface layer of the sintered layer to grow. In the latter half of the sintering step, the additive for closing the crack is mixed into the suction air, and the additive is supplied to the sintered layer in which the crack is generated and grows. .. 2. The additive according to claim 1, which is one of limestone, silica stone, blast furnace slag, steelmaking slag, dust collected in ironworks, and fine iron ore. Alternatively, it is a mixture of two or more kinds, and a method for producing a sinter.