JPH0633151A - Production of burned agglomerate - Google Patents

Abstract

PURPOSE:To enable the uniform coating of green pellets with powder coke in the process for production of the burned agglomerate to be executed by classifying powder ore prior to molding of the green pellets. CONSTITUTION:The powder ore is classified to >=2 kinds by a sieve 10. The fine grain components classified as the powder having fine particles are pelletized by a disk pelletizer 2 to produce the green pellets. These green pellets and the remaining coarse grained iron ore are respectively coated with the powder coke separately by a drum mixer 3 and a powder coke coating device 13 and are thereafter mixed. The mixture is calcined in an endless moving grate type burning furnace 4.

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 fired agglomerated ore suitable as a raw material for blast furnace or direct reduction ironmaking.

[0002]

2. Description of the Related Art As a raw material for a blast furnace or a raw material for direct reduction ironmaking, a fired agglomerated ore obtained by pelletizing fine iron ore and firing it is known, and its use is expanding.

Japanese Unexamined Patent Publication (Kokai) No. 63-149336 also describes a method for producing a fired agglomerated ore, which is produced as follows.

As shown in FIG. 6, a powdered iron ore having a particle size of 8 mm or less is mixed with a solvent such as quick lime, limestone and bentonite, and the basicity (CaO / SiO ₂ ) value in the calcined agglomerated ore is as follows.
Add to be about 1.0 to 2.5 and mix with Drum Mixer 1. Then, the obtained mixture is supplied to the desk pelletizer 2 and water is added to granulate the mixture to form raw pellets having a particle size of 3 to 13 mm. Next, the obtained raw pellets are supplied to the drum mixer 3, and powder coke of about 2.5 to 4.0 wt% is added to coat the surface of the raw pellets with the powder coke.
Raw pellets coated with powder coke are charged into an endless moving great type firing furnace 4. The layer of raw pellets loaded on top of the Great is the dry zone and ignition furnace 5 as the Great moves.
And is fired through a firing zone. That is, 15 in the dry zone
Exhaust gas at 0-350 ° C is sucked through the raw pellet layer and the raw pellet is dried. In the ignition furnace 5, a high-temperature combustion flame is blown onto the upper surface of the raw pellet layer to ignite the coated powder coke. In the firing zone, the combustion zone of the coated powder coke advances from the upper surface to the lower surface of the raw pellet layer by downward suction of the outside air, and the high temperature combustion gas generated in the combustion zone fires the raw pellets, and the solvent medium and The slag component of iron ore melts and solidifies. As a result, the fired pellets are combined into blocks by the solidified slag, and are discharged from the slag ends of the endless moving grate type furnace 4. The discharged block is crushed and sized by the crusher 16 and the screen 17, and becomes a fired agglomerated ore of a size suitable for blast furnace charging. The calcined ore thus produced has excellent reducing properties, does not flow unevenly toward the center when charged into the blast furnace, and has excellent air permeability.

Further, as an improvement technique of the above technique, as shown in FIG. 7, by using a sieve 10 of one to a plurality of stages, for example, +
The coarse ore of 5 mm or more is classified in advance, and the granulated property of the raw pellets is improved by increasing the fine ore content in the disc pelletizer 2 by sending the iron ore under the sieve to improve the granulation property of the raw pellets. A structure for improving yield and quality has also been proposed.

[0006]

However, in the improved construction, the coarse iron ore of indeterminate shape of 5 mm or more classified as shown in FIG.
Since the powdery coke is coated with the spherical raw pellets molded to 3 mm, the rolling state of the raw pellets in the coating drum mixer 3 deteriorates.

Therefore, the smooth coating of the powder coke on the surface of the raw pellets is hindered, resulting in a difference in the coke concentration. In terms of the yield / strength improving effect, the raw pellets are molded without classification. On the contrary, there is a problem that the effect is reduced as compared with the conventional configuration.

The present invention was devised in view of the above problems, and in a structure in which powder iron ore is classified before raw pellet molding, it is possible to uniformly coat the raw pellets with powder coke. It is intended to improve the yield and the strength of the produced fired agglomerated ore.

[0009]

Therefore, in the method for producing a fired agglomerated ore according to the present invention, a fine powder fraction is classified into two or more kinds, and fine granules classified as having fine particles are disc pelletized. Basically, the raw pellets and the remaining coarse iron ore are coated with powdered coke in different systems, respectively, and then mixed and further fired. Characteristic.

Further, in carrying out the above-mentioned manufacturing method, it is preferable that the amount of powder coke coated on the coarse iron ore is smaller than the amount of powder coke coated on the raw pellets.

Further, regarding the particle size of the powder coke coated on these, the particle size of the powder coke coated on the coarse iron ore may be made coarser than the particle size of the powder coke coated on the raw pellets.

[0012]

[Function] If the raw pellets having a nearly spherical shape and the coarse-grained ore of irregular shape are individually coated with the powder coke, the rolling state of the raw pellets in the mixer is not disturbed, and the coating of the powder coke is smooth and continuous. Is done in a regular manner. Therefore, the unburned or over-melted portion due to the variation in the powder coke coverage is reduced, and the yield and quality of the fired agglomerated ore are improved.

The reason for setting the addition amount and the particle size of the powder coke coated on the coarse-grained ore to be different from that of the raw pellets is as follows. That is, the coarse-grained ore is a dense single particle, and the heat energy required for sintering the fine powder is unnecessary. Coarse-grained ore is amorphous, and the coke coverage of powder coke is originally inferior, and fine coke with high flammability is disadvantageous in promoting the reaction in the coarse-grained portion.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a process diagram illustrating a process for producing a fired agglomerated ore according to the present invention. In the figure, one or a plurality of stages of sieves 10 are provided in the middle of a belt conveyor that conveys fine iron ore (blending powder). About 5 mm is suitable for the mesh size from the viewpoint of improving efficiency and yield. The undersized iron ore powder classified by the sieve 10 is charged into the B powder storage tank 6. On the other hand, the coarse sieving iron ore powder is sent by a belt conveyor 11, and further passed through a powder coke coating device 13 and further placed on the belt conveyor 15 after the drum mixer 3 for powder coke coating.

The sieved iron ore cut out from the B powder storage tank 6 is
It is charged into the drum mixer 1 together with the medium solvent cut out from the medium solvent storage tank 8 (usually quick lime is used) and the returned ore cut out from the returned ore storage tank 7. A required amount of water is added and mixed in this mixer 1. Further, this mixture is granulated by a disc pelletizer 2 and molded into a raw pellet of 5 to 8 mm. Molded raw pellets are conveyed on a belt conveyor
The powder is discharged onto the belt conveyor 9, and the coke powder is added on the belt conveyor 9 and charged into the drum mixer 3. The outer surface of the raw pellets is covered with the powder coke by the drum mixer 3, and the raw pellets are discharged onto the belt conveyor 15.

On the other hand, the coarse ore on the sieve of the sieve 10 is mixed with a required amount of water on the belt conveyor 11 and passes through the hopper 12 or does not pass through it directly, and is a mixing mixer or a mixing machine which is a coke powder coating device 13. To the smelter, and just before that, the required amount of powder coke is added and charged. Further, it is placed on the belt conveyor 15 via the belt conveyor 14.
The raw pellets and coarse sieving iron ore on the belt conveyor 15 are fired in the endless moving great type firing furnace 4, and then crushed and sized by the crusher 16 and the screen 17 to form a fired agglomerated ore.

2 to 5 are +5 mm grain size; 9.8 to 12.5
%, −125 μm particle size; for 34.1 to 38.9% fine iron ore,
Japanese Unexamined Patent Publication (Kokai) No. 63-149336 discloses a method for producing a fired agglomerated ore without sieving (conventional method 1) and calcination by sieving with a sieve having an opening of 5 mm, which is an improved structure. After the same method as in the agglomerated ore production method (conventional method 2) was performed, the raw iron pellets and coarse iron ore were individually coated with powdered coke under the conditions shown in Table 1 below. It is a graph which shows the comparative result about the yield and quality which each manufactured the calcination agglomerate by the method of this invention (Examples 1-4) which was performed, and was investigated at that time.

[0018]

[Table 1]

From the comparison results shown in these drawings, the method of the present invention further improves the conventional method (2) in terms of yield, tumbler strength, reduction rate (RI%) and reduction pulverization rate (RDI%). It was confirmed that this is an excellent method.

[0020]

EFFECTS OF THE INVENTION According to the method of the present invention described in detail above, the yield and the quality of the calcined agglomerate are improved as compared with the conventional method, and the amount of powder coke added to the classified coarse ore can be reduced. become.

[Brief description of drawings]

FIG. 1 is a process chart showing a process of carrying out the method of the present invention.

FIG. 2 is a graph showing the yield of baked agglomerated ore when the method of the present invention and the conventional method are carried out.

FIG. 3 is a graph showing each tumbler strength of the fired agglomerated ore.

FIG. 4 is a graph showing each reduction rate of the same calcined agglomerated ore.

FIG. 5 is a graph showing each reduction pulverization rate of the calcined agglomerated ore.

FIG. 6 is a process diagram showing a conventional process for producing a fired agglomerated ore.

FIG. 7 is a process diagram showing a manufacturing process of the same conventional fired agglomerated ore with the above configuration improved.

[Explanation of symbols]

 1, 3 Drum mixer 2 Disk pelletizer 4 Endless moving Great type firing furnace 5 Ignition furnace 6 B powder storage tank 9, 11, 14, 15 Belt conveyor 10 Sieve 13 Powder coke coating device

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masayasu Shimizu, Marunouchi 1-2-2, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Hideaki Sato 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Date Main Steel Pipe Co., Ltd.

Claims (3)

[Claims] 1. Fine iron ore is classified into two or more kinds, and fine granules classified as having fine particles are granulated by a disc pelletizer to produce raw pellets, and then the remaining coarse granules are prepared. In the method for producing a fired agglomerated ore, in which the grain fraction is mixed with this, and the powdered coke is further coated and fired, in the method for producing raw pellets and coarse iron ore, the powdered coke is coated in another system, then mixed and fired. A method for producing a fired agglomerated ore, comprising: 2. The method for producing a fired agglomerated ore according to claim 1, wherein the amount of powder coke coated on the coarse iron ore is smaller than the amount of powder coke coated on the raw pellets. Item 1. A method for producing a fired agglomerate item according to item 1. 3. The method for producing a fired agglomerated ore according to claim 1, wherein the particle size of the coke powder coated on the coarse iron ore is made coarser than the particle size of the coke powder coated on the raw pellets. The method for producing a fired agglomerated ore according to claim 1 or 2, characterized in that: