JPH06316718A - Manufacture of reduced iron briquette - Google Patents

Abstract

PURPOSE:To obtain a reduced iron briquette having little crack and little generation of powdering during the time of storing and carrying by slowly cooling the hot-state briquette forming the reduced iron obtd. by a direct reduction iron-making method at a specific cooling velocity. CONSTITUTION:The reducing iron obtd, by the direct reduction iron-making method is formed into briquette with a briquette machine apparatus and this hot-state briquette is slowly cooled with spray water at 150-250 deg.C/min cooling rate. Thereafter, the rapid cooling with the water may be executed. As another way, after slowly cooling the hot-state briquette with gas to 350-250 deg.C at 150-250 deg.C/min cooling velocity, this briquette is rapidly cooled with water. Further, as the other way, after slowly cooling the hot-state briquette with inert gas to 620-550 deg.C and successively, with spray water to 350-250 deg.C at 150-250 deg.C/min cooling velocity to both, this briquette is rapidly cooled with water. By this method, the purpose is achieved, and the metal obtaining efficiency is improved. and loss of the wt. during the storing and the carrying and bad influence given to the worker are improved, and reoxidation is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reduced iron briquette used as a raw material for melting a steelmaking furnace such as an electric furnace.

[0002]

Prior Art and Problems to be Solved by the Invention FIG.
FIG. 3 is a conceptual diagram of a reduced iron briquette manufacturing facility. The reduced iron briquette is generally manufactured in the following manner. That is, the raw material G such as pellets and lump ore is charged from the upper part of the reduction furnace 1 and reduced in the furnace to form reduced iron, which is discharged from the lower part. The reduced iron discharged from the lower part of the reduction furnace 1 is
It is supplied to a briquette machine facility 2 equipped with a caliber roll and a breaker that are continuously installed in the machine, pressure-molded into a plate shape having cutting grooves at predetermined intervals with a caliber roll, and this is cut into individual pieces with a breaker, and a high temperature (about Molded into reduced iron briquette B1 (about 700 ℃). Subsequently, this high-temperature reduced iron briquette B1 is put into the quench tank 3 and rapidly cooled with water in the tank 3, and the cooled reduced iron briquette B2 is discharged to the outside of the tank 3 by the carry-out conveyor 4.

On the other hand, the reduced iron briquette B2 produced as described above may be transported to an adjacent steelmaking plant after production and immediately melted in a steelmaking furnace, but it is produced mainly in a country where raw materials and fuel are inexpensive. And exported to countries that need iron sources. Therefore, after manufacturing, it is stored and transported several times including the export process. At the time of this storage and transportation, if the strength is low, cracking occurs and powder is generated, which reduces the amount. In addition, if dust is generated, it not only turns into dust and has a bad effect on the environment,
Alternatively, there is a problem that it has an adverse effect on equipment for carrying in and out of these, and also for people working there. Also,
When cracked, there is a problem of reoxidation of the reduced iron itself on the cracked surface, the metallization rate decreases, and the quality deteriorates. Further, due to cracking, pulverization, and reduction of metallization rate, melting yield in a steelmaking factory is reduced, and other operational problems are caused.

In order to improve the above problems, various improvements such as the production conditions of reduced iron briquette have been made in the past, but they are still not sufficient, and the problems of cracks and powders and the melting yield associated therewith are still unsatisfactory. Problems have been received from these sites and their improvement is expected.

The present invention has been made based on the above circumstances, and an object thereof is a reduced iron briquette for obtaining a reduced iron briquette which is less likely to be cracked during storage and transportation, and which is less likely to generate powder. Is to provide a method for manufacturing the same.

[0006]

In order to achieve the above object, one of the methods for producing a reduced iron briquette according to the present invention is to form reduced iron obtained by a direct reduction iron making method into briquettes by a briquette machine facility. , This high temperature reduced iron briquette, spray water 150 ℃ / min ~ 250
It is gradually cooled at a cooling rate of ° C / min.

[0007] One is to form reduced iron obtained by the direct reduction iron making method into briquettes by means of a briquette machine facility, and the reduced iron briquettes in a high temperature state are heated at 350 ° C to 2 ° C.
It is gradually cooled to 50 ° C with spray water at a cooling rate of 150 ° C / min to 250 ° C / min, and then rapidly cooled with water.

[0008] One is to form the reduced iron obtained by the direct reduction iron-making method into briquettes by a briquette machine facility, and the reduced iron briquettes in a high temperature state are heated at 350 ° C to 2 ° C.
Gas is gradually cooled to 150 ° C at a cooling rate of 150 ° C / min to 250 ° C / min, and then rapidly cooled with water.

One is to form the reduced iron obtained by the direct reduction iron-making method into briquettes by means of a briquette machine facility, and to make the reduced iron briquettes in a high temperature state at 620 ° C to 5 ° C.
An inert gas is used up to 50 ° C, and then 350 ° C to 250 ° C is gradually cooled with spray water at a cooling rate of 150 ° C / min to 250 ° C / min, respectively, and then rapidly cooled with water.

[0010]

The structure and operation of the present invention will be described in more detail below. The present inventors have investigated the cause of cracking of the reduced iron briquette obtained by the conventional manufacturing method described above, when the high temperature reduced iron briquette B1 is put into a water tank and rapidly cooled, residual stress remains inside, and It has been found that minute cracks are generated inside and it becomes easy to break even with a small impact. On the other hand, if this is improved and gradually cooled, a reduced iron briquette that is relatively hard to crack can be obtained, but it takes a long time to cool and productivity becomes a problem, and when slowly cooled to atmospheric temperature in the atmosphere, the reduced iron reoxidizes. There is a problem that the metallization rate is lowered.

Therefore, in the present invention, the reduced iron briquette B1 in a high temperature state is gradually cooled with spray water, or is gradually cooled with spray water or gas and then rapidly cooled with water. As the condition, a temperature lowering rate of about 150 ° C to 250 ° C per minute at the surface temperature of the briquette is preferable, and if the temperature lowering rate is faster than this, the properties of the obtained reduced iron briquette are not so different from those when quenched with water, It is easily cracked and has low strength. Further, if it is slow, it is no different from cooling in the air, the reduced iron is reoxidized and the metallization rate is lowered, and it takes a long time for cooling, and the productivity of reduced iron briquette becomes a problem.

[0012] When the water is rapidly cooled with spray water or gas and then rapidly cooled with water, it is preferable to carry out the slow cooling to 350 ° C to 250 ° C. If the slow cooling is stopped at a temperature higher than 350 ° C and then the water is rapidly cooled. However, it does not differ much from the case of rapid cooling with water. On the other hand, if the slow cooling is carried out to a temperature lower than 250 ° C, the slow cooling time will take longer, depending on the cooling rate, but the productivity will be a problem. At this time,
When the gas is used in the atmosphere, the reduced iron is reoxidized and the metallization rate is reduced. Therefore, it is preferable to use an inert gas as the gas, but an inert gas mixed with 20% or more of the atmosphere may be used.

In the case of gradually cooling with an inert gas, then with spray water and then with water, the gas is slowly cooled.
℃ ~ 550 ℃, then spray water gradual cooling to 350 ℃
It is better to perform up to ~ 250 ° C, and if the first slow cooling is performed with an inert gas, reoxidation of reduced iron can be suppressed even if cooling with spray water or water is performed later, and it is compared with subsequent spray water cooling. Although it is possible to obtain a reduced iron briquette having high strength that is hard to be cracked dynamically, if the temperature is out of the above range, the effect is reduced. Further, the reason why spray water is used is that it is easier to control slow cooling than gas alone.

[0014]

EXAMPLES Examples of the present invention will be described below.

(Embodiment 1) FIG. 1 is a schematic view of equipment to which the method for producing reduced iron briquette according to the present invention is applied. The reduction furnace 1 and the briquette machine facility 2 have the same configurations as those of the conventional technology, and the reduction furnace 1 reduces the raw material G such as pellets and lump ores in the furnace to reduce iron and discharge it from the lower part. The briquette machine facility 2 is connected to the reduction furnace 1 and forms the reduced iron discharged from the lower portion of the reduction furnace 1 into a high-temperature reduced iron briquette B1.

Approximately 7 immediately after molding obtained as described above
In this embodiment, the high-temperature reduced iron briquette B1 of 00 ° C. is charged onto a transfer equipment 8 in an annular cooler 7 having an air supply equipment 5 and an exhaust air equipment 6, and in this example, a mixed gas of an atmosphere and an inert gas. Was gradually cooled to 300 ° C. The temperature decrease rate of this slow cooling is 160 ° C for the first minute and 170 ° C for the second minute when the temperature is measured every minute.
The remaining 20 seconds was 80 ° C. After that, as in the conventional case, it was put into the quench tank 3 and rapidly cooled with water in the tank 3, and the cooled reduced iron briquette B3 was discharged to the outside of the tank 3 by the carry-out conveyor 4 to manufacture.

Reduced iron briquette B3 obtained above
For comparison, the strength and metallization rate were measured using reduced iron briquette B4 obtained by atmospheric cooling to 200 ° C and then water quenching, and reduced iron briquette B2 obtained only by conventional water quenching. investigated. The strength is measured by a drop strength test, and the method is to store an appropriate number of briquettes in an iron box.
The easiness of cracking and the easiness of generation of powder are evaluated by dropping 5 times from a height of 10 m, and then applying a sieve of each sieve size shown in FIG. 2 and performing a particle size analysis under the sieve.

As a result of the above investigation, the strength is as shown in FIG. 2, and the lumps of 38.1 mm or more which remain unbroken are at most 60% in the reduced iron briquette B2 by the conventional method, whereas the present invention Reduced iron briquette B3 by the method rises to about 88%. Although not shown in the drawing, the reduced iron briquette B4 produced by the comparative method is almost the same as the reduced iron briquette B3 produced by the method of the present invention.
It was the same as In addition, the generation of powder with a sieve size of 6.35 mm or less occurs in the reduced iron briquette B2 by the conventional method.
%, Whereas reduced iron briquette B3 according to the method of the present invention
Will decrease to about 2%. On the other hand, with respect to the metallization rate of the reduced iron discharged from the reduction furnace 1, the reduction rate of the reduced iron briquette B3 according to the method of the present invention is 0.5% or less, while the reduced metal according to the conventional method is reduced. Briquette
In B2 and the reduced iron briquette B4 by the comparison method, both
It was a large decrease of around 1.0%. From these, it can be seen that the reduced iron briquette B3 according to the method of the present invention is less likely to crack than the reduced iron briquette B2 according to the conventional method, generates less powder, and does not significantly lower the metallization rate.

(Embodiment 2) FIG. 3 is a schematic view of equipment to which the method for producing reduced iron briquette according to the present invention is applied. The reducing furnace 1 and the briquette machine facility 2 have the same configurations as those of the above-described first embodiment and the prior art. With these, the reduced iron discharged from the lower part of the reducing furnace 1 is heated to a high temperature in the same manner as in the above-mentioned first embodiment. Molded into reduced iron briquette B1.

Approximately 7 immediately after molding obtained as described above
In this embodiment, the high-temperature reduced iron briquette B1 of 00 ° C. is connected to the briquette machine facility 2 by an inert gas supply pipe 9
In the cooling chute 10 and then sent to the spray cooling type conveyor 12 further equipped with the spray nozzle 11 above and further to the carry-out conveyor 13. In this sending process, in the cooling chute 10 it takes about 30 seconds to reach about 600 ° C. In the first half 14 of the spray cooling type conveyor 12, the amount of water vapor in the spray nozzle 11 is controlled to take about 1.5 minutes to gradually cool to 300 ° C. In the latter half 15, the spray nozzle 11 is cooled. Cooled reduced iron briquette B5 was produced by increasing the amount of water and quenching.

Using the reduced iron briquette B5 obtained as described above, the strength and the metallization rate were investigated in the same manner as in Example 1. As a result, the strength is as shown in FIG. 2, and almost all of the reduced iron briquette B3 in Example 1 was used.
It was the same as that. The same applies to the metallization rate, which is the same as the metallization rate of the reduced iron discharged from the reduction furnace 1.
The decrease was 0.5% or less. Therefore, also in this example, it is understood that the reduced iron briquette B5 according to the method of the present invention is less prone to cracking than the reduced iron briquette B2 according to the conventional method, less powder is generated, and the metallization rate does not decrease so much.

(Embodiment 3) FIG. 4 is a schematic view of equipment to which the method for producing reduced iron briquette according to the present invention is applied. The reducing furnace 1 and the briquette machine facility 2 have the same configurations as those of the above-described first embodiment and the prior art. With these, the reduced iron discharged from the lower part of the reducing furnace 1 is heated to a high temperature in the same manner as in the above-mentioned first embodiment. Molded into reduced iron briquette B1.

Approximately 7 immediately after molding obtained as described above
In this embodiment, the high-temperature reduced iron briquette B1 of 00 ° C. is sent to a spray cooling type conveyor 17 further equipped with a spray nozzle 16 above the inside of the briquette machine equipment 2 and further to an unloading conveyor 18 for spray cooling in this sending process. In the type conveyor 17, the amount of steam of the spray nozzle 16 is controlled to about 3
Reduced iron briquette that has been slowly cooled to 70 ° C over a period of time
B6 was manufactured.

Using the reduced iron briquette B6 obtained as described above, the strength and the metallization rate were investigated in the same manner as in Example 1. As a result, the strength is as shown in FIG. 2, and almost all of the reduced iron briquette B3 in Example 1 was used.
It was the same as that. The same applies to the metallization rate, which is the same as the metallization rate of the reduced iron discharged from the reduction furnace 1.
The decrease was 0.5% or less. Therefore, also in the present example, it is understood that the reduced iron briquette B6 according to the method of the present invention is less likely to crack than the reduced iron briquette B2 according to the conventional method, generates less powder, and does not significantly lower the metallization rate.

(Embodiment 4) FIG. 5 is a schematic view of equipment to which the method for producing reduced iron briquette according to the present invention is applied. The reducing furnace 1 and the briquette machine facility 2 have the same configurations as those of the above-described first embodiment and the prior art. With these, the reduced iron discharged from the lower part of the reducing furnace 1 is heated to a high temperature in the same manner as in the above-mentioned first embodiment. Molded into reduced iron briquette B1.

Approximately 7 immediately after molding obtained as described above
In this embodiment, the high-temperature reduced iron briquette B1 having a temperature of 00 ° C. is put into a spray cooling type conveyor 20 having a spray nozzle 19 above the inside of the briquette machine facility 2 and the steam amount of the spray nozzle 19 is controlled. Approx. 340 ° C over 1.5 minutes
Slowly cooled to. After that, as in the conventional method, the quench tank 3
It was put into a tank and rapidly cooled with water in the tank 3, and the cooled reduced iron briquette B7 was discharged to the outside of the tank 3 by the carry-out conveyor 4 to manufacture.

Using the reduced iron briquette B7 obtained as described above, the strength and the metallization rate were investigated in the same manner as in Example 1. As a result, the strength is as shown in FIG. 2, and almost all of the reduced iron briquette B3 in Example 1 was used.
It was the same as that. The same applies to the metallization rate, which is the same as the metallization rate of the reduced iron discharged from the reduction furnace 1.
The decrease was 0.5% or less. Therefore, also in this example, it is understood that the reduced iron briquette B7 according to the method of the present invention is less liable to crack than the reduced iron briquette B2 according to the conventional method, less powder is generated, and the metallization rate is not significantly lowered. In addition, this embodiment has the highest productivity as compared with the above-described first to third embodiments, and is economical in terms of equipment.

[0028]

As described above, according to the method for producing a reduced iron briquette according to the present invention, there are few cracks during storage and transportation, generation of powder due to cracks is small, and the metallization rate is good. Reduced iron briquettes can be obtained, which can reduce the reduction of reduced iron briquettes during storage, transportation, dust carriers, ships, and equipment for loading and unloading them, and the adverse effects on people working there. It Moreover, since the number of cracks is reduced, the reoxidation of the reduced iron itself at the cracked surface is also reduced, and the quality is stable.

[Brief description of drawings]

FIG. 1 is a schematic diagram of equipment to which a method for manufacturing a reduced iron briquette according to the present invention is applied.

FIG. 2 is a graph showing the results of a drop strength test of a briquette of the present invention and a conventional briquette in comparison.

FIG. 3 is a schematic view of equipment of another embodiment to which the method for producing a reduced iron briquette of the present invention is applied.

FIG. 4 is a schematic view of equipment of another embodiment to which the method for producing reduced iron briquette of the present invention is applied.

FIG. 5 is a schematic view of equipment of another embodiment to which the method for producing reduced iron briquette of the present invention is applied.

FIG. 6 is a schematic diagram of a conventional reduced iron briquette manufacturing facility.

[Explanation of symbols]

1: Reduction furnace 2: Briquette machine equipment 3: Quench titanium 4: Carry-out conveyor 7: Annular cooler 8: Transfer equipment 9: Air supply pipe 10: Cooling chute 11, 16, 19: Spray nozzle 12, 17, 20: Spray cooling type Conveyors 13 and 18: Carry-out conveyor G: Raw material B1: High-temperature reduced iron briquettes B2, B3, B5, B6,
B7: Reduced iron briquette

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsu Sugano Venezuela, Estado Bolivar State, Puerto Ordaz City, Zona Postal 8015, Apartado 497, Opco In-house (72) Inventor Tsushita Shu Chuo-ku, Kobe City 1-3-18 Wakihamacho Kobe Steel Works, Ltd. Kobe Head Office

Claims (4)

[Claims] 1. Reduced iron obtained by the direct reduction iron manufacturing method is molded into briquettes by a briquette machine facility, and the reduced iron briquettes in a high temperature state are sprayed with water at 150 ° C.
/ Min-250 ° C / min A method for producing a reduced iron briquette, characterized by slow cooling. 2. The method for producing a reduced iron briquette according to claim 1, wherein the gradual cooling with spray water is performed at 350 ° C. to 250 ° C.
A method for manufacturing reduced iron briquette, which is rapidly cooled with water. 3. Reduced iron obtained by the direct reduction iron manufacturing method is molded into briquettes by a briquette machine facility, and the reduced iron briquettes in a high temperature state are heated to 350 ° C. to 250 ° C. in gas at 150 ° C./min to 250 ° C. A method for producing a reduced iron briquette, which comprises gradually cooling at a cooling rate of 1 minute / minute and then rapidly cooling with water. 4. Reduced iron obtained by the direct reduction iron manufacturing method is molded into briquettes by a briquette machine facility, and the reduced iron briquettes in a high temperature state are heated at 620 ° C. to 550 ° C. with an inert gas, and subsequently at 350 ° C. A method for producing a reduced iron briquette, which comprises gradually cooling up to 250 ° C with spray water at a cooling rate of 150 ° C / min to 250 ° C / min and then rapidly cooling with water.