JP6724677B2 - Granulating apparatus and granulating method for sintering raw material - Google Patents

Description

The present invention relates to a granulating apparatus and a granulating method for sintering raw materials.

Sinter ore used as a blast furnace raw material is generally manufactured through the following processing steps of the sintering raw material. Iron ore with a particle size of 10 mm or less, dust collected from a dust collector, powdered ore such as undersize powder (return ore) after being discharged from a sintering machine, limestone containing CaO such as limestone as a binder A drum mixer is charged with a powdered raw material, an olivine that improves the reducibility of sinter, a MgO-containing powdered raw material such as dolomite, and a solid fuel-based powdered raw material that serves as a heat source such as coke dust and anthracite, and is charged in an appropriate amount. Water is added, mixed and granulated to form a granulated product called pseudo particle. The granulated pseudo particles are charged into a sintering machine such as a Dwightroid type sintering machine and fired to form a sintered ore.

The air permeability, flammability, and sintering state during the sintering operation are affected by the properties of the granulated pseudo particles. For example, among the powdered coke to be added, fine powdered coke is buried inside the pseudo particles, or when the coarse powdered coke is covered with a fine ore layer adhering to the outer peripheral surface, oxygen supply to the powdered coke is hindered, The combustibility of powder coke deteriorates and the sintering yield decreases.

As a method for improving this, in Patent Document 1, sintering raw materials other than the solid fuel powder raw material (powder coke) are charged from the charging opening of the drum mixer until the sintering raw material reaches the discharging opening of the drum mixer. A method for adhering the solid fuel type powder raw material to the surface of the granulated material excluding the solid fuel type powder raw material is disclosed by adding the solid fuel type powder raw material in the region where the residence time is within the range of 10 seconds to 120 seconds. Has been done.

Further, in Patent Document 2, a coarse grain fraction B containing 90% by mass or more of a particle size of 1 mm or more in the powder coke is added on the downstream side of the drum mixer, and a fine grain containing 90% by mass or more of a particle size of less than 1 mm in the powder coke. A method of adding Minute A upstream of the drum mixer is disclosed.

JP, 2003-160815, A JP2012-92384A

However, in the case of the method described in Patent Document 1, when the pouring position of the powder coke is close to the discharge side of the drum mixer, the granulated product obtained by granulating the sintering raw material is charged into the sintering pallet of the sintering machine. A part of the coke having a particle diameter of less than 1 mm (hereinafter, also referred to as “fine coke”) attached to the surface of the granulated product is separated from the surface of the granulated product. The separated fine coke enters the gaps of the granulated material loaded on the sintering pallet and deteriorates ventilation, and the yield of the sintered ore decreases. Furthermore, there is also fine coke that is charged into the sintering pallet without adhering to the surface of the granulated product, and there is the problem that the same aeration deterioration is caused.

Further, in the case of the method described in Patent Document 2, since coarse coke is added on the downstream side of the drum mixer, the outer peripheral surface of the coarse coke is not covered with fine ore, but fine coke is provided on the upstream side of the drum mixer. Since it is added in, the fine coke is deeply taken into the adhering powder layer made of the fine ore formed around the core particles made of the coarse ore, and the combustibility of the fine coke is deteriorated. Further, there is a demerit that at least two storage tanks are required in addition to the classification equipment having a mesh size of 1 mm.

The present invention has been made in view of such circumstances, and a granulating apparatus and a granulating apparatus for a sintering raw material capable of improving the combustibility of a powder coke for producing a sinter ore and improving the sintering yield as compared with the prior art. The purpose is to provide a method.

In order to achieve the above-mentioned object, a sintering raw material granulating apparatus according to a first aspect of the present invention comprises a drum mixer for granulating the sintering raw material, and charging a coke powder into the drum mixer from the discharge side of the drum mixer. And a spray nozzle installed at the downstream end of the conveyor and spraying air toward the upstream side of the drum mixer.

A second aspect of the invention is to charge the sintering raw material excluding powdered coke from a charging port of a drum mixer to granulate, and to load the powdered coke into the drum mixer from a discharge side of the drum mixer by a conveyor. In the granulation method of sintering raw material,
Air directed toward the upstream side of the drum mixer is blown onto the powder coke falling from the downstream end of the conveyor into the drum mixer.

In the present invention, in order to load the powder coke at an appropriate position according to the particle size, air directed toward the upstream side of the drum mixer is blown to the powder coke falling from the discharge side of the drum mixer into the drum mixer. As a result, light fine coke scatters and drops toward the upstream side of the drum mixer, and heavy coarse coke drops near the discharge side of the drum mixer.

According to the present invention, since the fine coke falls to the upstream side of the drum mixer, the granulation time is sufficiently secured, and the proportion of the fine coke remaining as the fine powder without adhering to the surface of the granulated product becomes small. Further, since the coarse-grained coke falls near the discharge side of the drum mixer, the outer peripheral surface is not covered with the fine ore. As a result, the combustibility of the powder coke is improved as compared with the conventional one, and the sintering yield can be improved.

6 is a graph showing the relationship between the distance from the conveyor drop position and the powder coke existence ratio. 6 is a graph showing the relationship between the distance from the conveyor drop position and the average particle size of powder coke. It is a schematic diagram which shows the structure of the granulation apparatus of the sintering raw material which concerns on one embodiment of this invention. It is a perspective view of the injection nozzle installed in the conveyor downstream end.

Subsequently, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention.

As described above, the fine coke and the coarse coke composing the coke have proper positions in the drum mixer.
Coarse powder coke is preferably placed near the discharge side of the drum mixer because the fine ore covers the outer peripheral surface when the residence time in the drum mixer becomes long.
On the other hand, fine coke will be buried in the granulated product if the residence time in the drum mixer is too long, and if the residence time is too short, it will not adhere sufficiently to the granulated product and will easily peel off. It will exist as fine powder without wearing it. Therefore, it is desirable to add the fine coke to the vicinity of the center of the drum mixer.

As a method of changing the charging position without classifying coarse coke powder and fine coke powder, the inventors of the present invention spray the air toward the upstream side with respect to the coke powder fed by the conveyor from the downstream side of the drum mixer. Conceived. As a result, the heavy coarse-grained coke falls near the loading position on the conveyor without being affected by the air, and the light fine-powder coke falls further upstream by the air.

The present inventors confirmed the effect of dispersing coarse-grain coke and fine coke by air as follows.
Sheets are laid on the bottom of the drum mixer with the drum mixer stopped, and the coke dust is loaded into the drum mixer by the conveyor from the discharge side of the drum mixer, and the case where air is jetted from the jet nozzle and the case where it is not jetted The flight distance of the powder coke was investigated respectively. FIG. 1 shows the relationship between the distance from the conveyor dropping position and the powder coke existence ratio, and FIG. 2 shows the relationship between the distance from the conveyor falling position and the powder coke average particle size.

In addition, the dropping position of the conveyor was 3 m upstream from the discharge port of the drum mixer, and the convey speed of the conveyor was 90 m/min. Further, as the injection nozzles, five 50 mm wide flat air nozzles having 16 injection holes each having a diameter of 1.2 mm were used. The pressure per flat air nozzle is 0.53 MPa, and the air volume is 2200 NL/min.

The following can be seen from these figures.
・When air is blown to the powder coke, the smaller the particle size of the powder coke, the farther it will fly in the drum mixer. The falling position of the scattered powder coke is approximately 3000 mm from the falling position of the conveyor.
-When air is not blown to the powder coke, the position where the powder coke falls is about 1000 mm from the position where the conveyor falls.

FIG. 3 shows the structure of a sintering material granulating apparatus according to an embodiment of the present invention.
As shown in the figure, the present granulating apparatus includes a drum mixer 10 for mixing and granulating sintering raw materials, and conveyors 11 and 12 for charging the sintering raw material into the drum mixer 10 from a charging port of the drum mixer 10. And a conveyor 13 for charging the powder coke into the drum mixer 10 from the discharge side of the drum mixer 10, and at the downstream end of the conveyor 13, the powder coke falling from the downstream end of the conveyor 13 into the drum mixer 10 is provided. An injection nozzle 14 for blowing air is installed.
Further, a powder coke storage tank 18 is installed above the conveyor 13 on the upstream side, and an iron ore storage tank 15, a limestone storage tank 16, and a MgO raw material storage tank 17 are installed adjacent to each other above the conveyor 11. ing.

The iron ore storage tank 15 stores powdered ore. The stored fine ore is supplied onto the conveyor 11 by the raw material cutting device 19.
The limestone storage tank 16 stores powdery limestone. Limestone is preferably placed adjacent to the iron ore in the sinter, which produces a melt at elevated temperatures. The stored limestone is supplied onto the conveyor 11 by the raw material cutting device 20.
The MgO raw material storage tank 17 stores powdery MgO raw material. The MgO raw material serves as a raw material for improving the reducibility of the sinter. The stored MgO raw material is supplied onto the conveyor 11 by the raw material cutting device 21.
The powder coke storage tank 18 stores the powder coke. The coke dust contacts and reacts with oxygen in the air in the sintering machine, and the heat of oxidation accelerates the melt formation. The stored powder coke is supplied onto the conveyor 13 by the raw material cutting device 22.

The downstream portion of the conveyor 13 for charging the powder coke into the drum mixer 10 is inserted into the drum mixer 10 through the outlet of the drum mixer 10. As shown in FIG. 4, a plurality of injection nozzles 14 (five in the present embodiment) are installed in the lower part of the downstream end of the conveyor 13 along the width direction of the conveyor 13. Each injection nozzle 14 injects air toward the upstream side of the drum mixer 10.
As the injection nozzle 14, for example, a flat air nozzle or the like can be used. The flat air nozzle has a rectangular cross section and is provided with a plurality of air blowout holes each having a diameter of about 1 mm at its tip.

Next, a method of granulating a sintering raw material using the granulating apparatus having the above configuration will be described.
The powdered ore stored in the iron ore storage tank 15 is cut out by the raw material cutting device 19 and dropped on the conveyor 11. Next, an amount of limestone corresponding to approximately 12% by mass of the powdered ore dropped on the conveyor 11 is cut out from the limestone storage tank 16 by the raw material cutting device 20 and dropped on the conveyor 11. Further, the MgO raw material in an amount corresponding to about 1.5 mass% of the powdered ore dropped on the conveyor 11 is cut out from the MgO raw material storage tank 17 by the raw material cutting device 21 and dropped on the conveyor 11.

These sintering raw materials dropped on the conveyor 11 are transferred to the conveyor 12 and inserted into the drum mixer 10 from the charging port of the drum mixer 10.
The rotation speed of the drum mixer 10 is 5 rpm to 10 rpm. The drum mixer 10 is rotated for about 0.5 to 3 minutes to stir the powdered ore, limestone, and MgO raw material, and part of the powdered ore is granulated into pseudo particles.

On the other hand, a powder coke corresponding to about 3.0% by mass of the powder ore charged in the drum mixer 10 is cut out from the powder coke storage tank 18 by the raw material cutting device 22 and is dropped on the conveyor 13. The downstream end of the conveyor 13 is located on the upstream side by about 3 m from the discharge port of the drum mixer 10, and the powder coke dropped on the conveyor 13 is dropped into the drum mixer 10 from the downstream end of the conveyor 13.

In the present embodiment, air toward the upstream side of the drum mixer 10 is blown from the injection nozzle 14 installed at the downstream end of the conveyor 13 to the powder coke dropped from the downstream end of the conveyor 13 into the drum mixer 10. .. As a result, the light fine coke scatters and drops toward the upstream side of the drum mixer 10, and the heavy coarse coke drops near the discharge side of the drum mixer 10.

Since the appropriate air pressure and air volume vary depending on the particle size distribution of the powder coke and the operating conditions of the drum mixer 10, they may be set appropriately while confirming the effects such as the sintering yield.

Although one embodiment of the present invention has been described above, the present invention is not limited to the configuration described in the above-mentioned embodiment at all, and within the scope of matters described in the claims. It also includes other possible embodiments and modifications. For example, although one drum mixer is used in the above embodiment, two or more drum mixers may be used.

A verification test carried out to verify the effect of the present invention will be described.
The drum mixer consists of a primary drum mixer and a secondary drum mixer. The sintering raw material except for the powder coke is charged from the inlet of the primary drum mixer, and the powder coke is charged from the discharge side of the secondary drum mixer. I entered.
The inner diameter of the primary drum mixer is 4400 mm, the length is 15.5 m, and the rotation speed is 8 rpm. On the other hand, the inner diameter of the secondary drum mixer is 5000 mm, the length is 22.5 m, and the rotation speed is 6.2 rpm.

The position of the downstream end of the conveyor for charging the powder coke was set to the position 3 m upstream from the outlet of the secondary drum mixer. The conditions of the injection nozzle are the same as those of the test shown in FIGS. 1 and 2.

Iron ore, limestone, dolomite, and coke powder were used as sintering raw materials.
The powder coke used was crushed to an average particle size of 2.0 mm. However, the ratio of 0.25 mm under is 12% by mass.

The test results are shown in Table 1. In addition, Comparative Example 1 is an example in which the powder coke is charged from the downstream side of the secondary drum mixer only by the conveyor, and Comparative Example 2 is an example in which the powder coke is charged from the upstream side of the secondary drum mixer. Further, the sintering yield is product/(product + return ore)×100%.

From the same table, Comparative Example 1 has a higher sintering yield and burning layer burning rate (Flame Front Speed) than Comparative Example 2, and Example has a higher sintering yield and burning layer burning rate than Comparative Example 1. I understand.

10: Drum mixer, 11, 12, 13: Conveyor, 14: Injection nozzle, 15: Iron ore storage tank, 16: Limestone storage tank, 17: MgO raw material storage tank, 18: Powder coke storage tank, 19, 20, 21 22: Raw material cutting device

Claims (2)

A drum mixer for granulating the sintering raw material, a conveyer for charging powder coke into the drum mixer from the discharge side of the drum mixer, and a downstream end of the conveyer, which is installed on the upstream side of the drum mixer. An apparatus for granulating a sintering raw material, comprising: an injection nozzle for injecting air. In the granulation method of the sintering raw material, the sintering raw material excluding the powder coke is charged from the charging port of the drum mixer to granulate, and the powder coke is charged from the discharge side of the drum mixer into the drum mixer by a conveyor. ,
A method for granulating a sintering raw material, characterized in that air directed toward an upstream side of the drum mixer is blown to powder coke falling from the downstream end of the conveyor into the drum mixer.

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