KR20120073553A - Manufacturing method of mixing raw material for sintering - Google Patents

Abstract

PURPOSE: A method for manufacturing mixing materials for sintering is provided to improve the internal ventilation property of a sintering bed by increasing the intensity of small pellets, thereby increasing sintering productivity. CONSTITUTION: A method for manufacturing mixing materials for sintering is as follows. Very finely pulverized iron ores and water binders are mixed and assembled to manufacture small pellets(S10). Starch solution is dried after spreading on the surface of the small pellets so that a coating layer composed of hardened starch can be formed(S20). The small pellets, sub-materials, and solid fuel are mixed and assembled(S30).

Description

Manufacturing method of compounding raw material for sintering {MANUFACTURING METHOD OF MIXING RAW MATERIAL FOR SINTERING}

The present invention relates to a blended raw material for sintering for the production of sintered ore, and more particularly to a method for producing a blended raw material for sintering which can increase the strength of the small pellets to improve the sintering productivity.

In general, the manufacturing process of the raw material for sintering according to the selective granulation method is a step of producing small pellets by adding water to the ultra fine iron ore, mixing and assembling with a pelletizer, and subsidiary materials (such as limestone and quicklime) CaO-containing raw materials or SiO ₂ -containing raw materials such as silica, serpentine) and solid fuels (coke and anthracite, etc.) and the like, and then reassembling.

The raw material for sintering is charged into the sintering apparatus, the flame is ignited in the coke as fuel while passing through the ignition furnace, and the air in the air is sucked into the sintered surface layer by the suction pressure of the blower to undergo the sintering process. Through this process, a sintered ore in a semi-molten state is manufactured, and the manufactured sintered ore is transferred to a furnace (blast furnace), which is a later process.

Small pellets made of only finely divided iron ore and moisture have low strength and thus lower the air permeability inside the sintered bed during the manufacture of the sintered ore. Therefore, the sintering productivity is lowered, the quality of the sintered ore is lowered, causing a problem of increasing the amount of coke used for sintering.

The present invention is to provide a method for producing a blended raw material for sintering to increase the strength of the small pellets to improve the air permeability inside the sintered bed during the sintering process, as a result can increase the sintering productivity.

Method for producing a blended raw material for sintering according to an embodiment of the present invention, the step of preparing small pellets by mixing and assembling the ultra fine iron ore and the water binder, and applying a starch aqueous solution to the surface of the small pellets to dry Forming a coating layer made of starch, and mixing and reassembling the small pellets with the sub- and solid fuels.

In the manufacture of small pellets, it is possible to add iron ore by adding a powdered iron ore to the surface of the iron ore, which is a nuclear particle, through a moisture binder. The content of the ultra fine iron ore may be less than the content of the iron ore.

The starch aqueous solution contains 0.5% to 3% starch and may be sprayed with a spray nozzle. The starch aqueous solution may be applied to the surface of the small pellets in a thickness of 0.2mm to 0.5mm. Drying may be performed for 1 to 3 minutes using hot air at a temperature of 90 ℃ to 110 ℃.

As the strength of the small pellets increases, the sintering productivity may be improved by improving the air permeability inside the sintered bed in the process of manufacturing the sintered ore. In addition, since the coating layer is formed only on the surface of the small pellets, it is possible to minimize the additional cost of coating the material.

1 is a flow chart showing a method for producing a blended raw material for sintering according to an embodiment of the present invention.
2 is a block diagram showing an apparatus for producing a blended raw material for sintering.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

1 is a flow chart showing a method of manufacturing a blended raw material for sintering according to an embodiment of the present invention, Figure 2 is a block diagram showing a manufacturing apparatus of a blended raw material for sintering.

1 and 2, the method for producing a blended raw material for sintering according to the present embodiment is a first step (S10) of producing small pellets by mixing and assembling ultra fine iron ore and a water binder, and the surface of the small pellets And a second step (S20) of forming a coating layer made of cured starch by applying a starch aqueous solution to the dried starch, and a third step (S30) of mixing and reassembling an auxiliary material and a solid fuel into small pellets on which the coating layer is formed. do.

In the first step (S10), the fine iron ore together with the finely divided iron ore may be used in the manufacture of small pellets. The iron ore and the fine iron ore are stored in their respective storage bins 11 and 12, and the storage bins 11 and 12 are connected to the first mixer 21 so that the first iron ore and the fine iron ore are connected to the first mixer 21. To supply. The first mixer 21 uniformly stirs the provided iron ore, the ultra fine iron ore and the moisture binder at high speed.

The iron ore has a size of 4 mm or less, and the ultra fine iron ore has a smaller size than the iron ore, for example, a particle size of 100 μm or less on average. The iron ore functions as a nuclear particle, and the ultra fine iron ore is attached to the surface of the nuclear particle through a moisture binder to surround the nuclear particle. The content of the ultra fine iron ore as an attached particle is less than the content of the iron ore as a nuclear particle. For example, a mixture of 70% by weight iron ore and 30% by weight fine iron ore can be used.

The first mixer 21 is connected to the pelletizer 22 to supply a mixture of the iron ore and the finely divided iron ore to the pelletizer 22. The pelletizer 22 has a rotating fan (not shown), and the mixture supplied from the first mixer 21 is granulated by gradually growing particles while flowing over the rotating pan. The small pellets may have a size of approximately 3 mm to 8 mm.

In the second step (S20) to form a coating layer on the surface of the small pellets to increase the strength of the small pellets. To this end, the pelletizer 22 is connected to the coating device 23 to supply the small pellets to the coating device 23, and in the coating device 23 to apply a starch aqueous solution having a viscosity to the surface of the small pellets. The coating device 23 may be connected to the drying device 24 to supply the small pellets to the drying device 24, and to dry the small pellets with hot air in the drying device 24. When using hot air, the drying time can be shortened.

The coating apparatus 23 is equipped with a spray nozzle (not shown), and apply | coats a starch aqueous solution to the surface of a small pellet. The starch aqueous solution may comprise 0.5% to 3% starch. If the starch content in the starch aqueous solution is less than 0.5%, the effect of improving the strength of the small pellets according to the coating layer formation is insignificant, and if it exceeds 3%, the spray nozzle for applying the starch aqueous solution is blocked, making it difficult to apply the starch aqueous solution.

Table 1 shows the results of the ease of spraying evaluation according to the concentration of the starch aqueous solution.

As shown in the table, it can be seen that when the concentration of the starch aqueous solution exceeds 3%, an abnormality occurs in the spray nozzle and the coating performance is lowered.

The aqueous starch solution sprayed from the coating apparatus 23 acts on the ultrafine iron ore, which is the adherent particles among the particles constituting the small pellets, to bond them together. The starch aqueous solution may be applied to the small pellets to a thickness of 0.2mm to 0.5mm. If the coating thickness of the starch aqueous solution is less than 0.2mm, the effect of improving the binding strength of the ultra fine iron ores is insignificant, and if it exceeds 0.5mm, only the material consumption increases without further increasing the binding strength of the ultrafine iron ores.

In the drying apparatus 24, hot air is applied to the small pellets to dry the small pellets to which the starch aqueous solution is applied. Starch hydrolyzed by water causes a hardening phenomenon as the water evaporates during the drying process, and the hardened starch is bonded to each other to increase the strength of the small pellets. The coating layer of small pellets consists of cured starch.

Drying may be performed using hot air at 90 ° C to 110 ° C. If the drying temperature is less than 90 ° C., the drying time is increased. If the drying temperature is more than 110 ° C., the moisture of the small pellets is evaporated, resulting in a decrease in the strength of the small pellets. The drying time may be from 1 minute to 5 minutes based on hot air at about 100 ° C. When this condition is satisfied, the strength of the small pellets can be secured the highest.

The drying apparatus 24 may be connected to a sintering apparatus (not shown) to use an arrangement generated in the sintering process as hot air.

The strength measurement results of the small pellets according to the coating layer formation condition and the coating layer formation conditions are shown in Table 2 below.

The sample (small pellet) used in the experiment contained 70% of iron ore of 4 mm or less size as nuclear particles and 30% of ultrafine iron ore of average size of 100 μm as adhesion particles. As the starch aqueous solution, a starch 2% aqueous solution having easy spraying was used. The amount of sample used in the experiment is 300g, the particle size of the sample is 4mm to 5mm. The sample was dropped freely five times at a height of 2 meters, and a sample having a particle size of 4 mm or more that was not broken by a drop impact was collected. The drop strength was measured by dividing the weight of the collected sample by the weight of the original sample and multiplying by 100.

In the case of the sample formed with the coating layer, immediately after application of starch aqueous solution, and dried for 3 hours after application of starch aqueous solution, and then dried for 2 minutes, 5 minutes, 10 minutes, and 20 minutes in hot air at approximately 100 ° C after application of starch aqueous solution, respectively. Drop strength was measured.

When the coating layer is formed on the surface of the sample, it can be confirmed that the drop strength is improved compared to the comparative example in which the coating layer is not formed. However, if the hot air drying time is more than 10 minutes, the moisture of the small pellets itself evaporates and the drop strength is lowered. Therefore, the hot air drying time is preferably 1 minute to 5 minutes.

The drying device 24 is connected with the second mixer 25 to supply the small pellets to the second mixer 25. The second mixer 25 is connected to the storage bin 13 containing the iron ore, the storage bin 14 containing the subsidiary materials, and the storage bin 15 containing the solid fuel, thereby receiving iron ores, secondary raw materials and solid fuel therefrom.

In the third step (S30) to mix and reassemble the iron ore, secondary raw materials and solid fuel to the small pellets completed in the second step (S20) to complete the raw material for sintering. Iron ores may include one or more of hematite, maramamba ore, brown iron ore, and magnetite. The adjuvants may include one or more of semi-ore, limestone, quicklime, quartzite, dolomite, and serpentine. Solid fuels include coke or anthracite.

The compounding raw material for sintering completed in the third step S30 is introduced into the surge hopper 26 and charged into a sintering apparatus (not shown). In FIG. 2, reference numeral 27 denotes an upper light hopper for introducing upper ore into the sintering apparatus.

As the small pellets in this embodiment are surrounded by a coating layer composed of starch, they realize higher strength than conventional small pellets assembled with ultrafine iron ore and a water binder. Therefore, the compounding raw material for sintering of this embodiment does not deteriorate the air permeability inside the sintered bed in the process of manufacturing the sintered ore, thereby increasing the sintering productivity. In addition, the starch is coated only on the surface of the small pellets, thereby minimizing the additional cost of coating the material.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Of course.

11 ~ 15: storage bin 21: first mixer
22: pelletizer 23: coating apparatus
24: drying apparatus 25: second mixer
26: surge hopper 27: upper light hopper

Claims (6)

Mixing and assembling the ultra fine iron ore and the moisture binder to produce a small pellet;
Forming a coating layer made of cured starch by applying an aqueous starch solution onto the surface of the small pellets and then drying it; And
Mixing and reassembling the small pellets and the sub- and solid fuels
Method for producing a blended raw material for sintering comprising a. The method of claim 1,
The method for producing a blended raw material for sintering to add the fine iron ore in the manufacture of the small pellets to attach the ultra fine iron ore to the surface of the iron ore as nuclear particles via the moisture binder. The method of claim 2,
The method of producing a blended raw material for sintering the content of the ultra fine iron ore is less than the content of the iron ore. 4. The method according to any one of claims 1 to 3,
The starch aqueous solution contains 0.5% to 3% starch, the method of producing a blended raw material for sintering is sprayed with a spray nozzle. The method of claim 4, wherein
The starch aqueous solution is a method for producing a blended raw material for sintering is applied to the surface of the small pellets in a thickness of 0.2mm to 0.5mm. The method of claim 4, wherein
The drying is a method of producing a blended raw material for sintering proceeds for 1 to 3 minutes using hot air at a temperature of 90 ℃ to 110 ℃.

Images