WO2008078937A1

WO2008078937A1 - Apparatus for restoring fine irons and apparatus for manufacturing molten iron comprising the same

Info

Publication number: WO2008078937A1
Application number: PCT/KR2007/006774
Authority: WO
Inventors: Su-Yeon Kim; Il-Hyun Cho; Do-Seung Kim
Original assignee: Posco
Priority date: 2006-12-27
Filing date: 2007-12-24
Publication date: 2008-07-03
Also published as: CN101578378A; CN101578378B; KR100840265B1

Abstract

The present invention relates to an apparatus for restoring fine ore and an apparatus for manufacturing molten iron including the same. An apparatus for restoring fine iron includes a fine iron storage bin, and a cyclone that collects fine iron in an offgas that is supplied from the fine iron storage bin.

Description

APPARATUS FOR RESTORING FINE IRONS AND APPARATUS FOR MANUFACTURING MOLTEN IRON COMPRISING THE SAME

Technical Field The present invention relates to an apparatus for restoring fine ore and an apparatus for manufacturing molten iron provided with the same, and more specifically to an apparatus for restoring fine ore to collect fine ore existing in an offgas and recycle it and an apparatus for manufacturing molten iron including the same. Background Art

The iron and steel industry is a core industry that supplies the basic materials needed in construction and in the manufacture of automobiles, ships, home appliances, and many other products we use. It is also an industry with one of the longest histories that has progressed together with humanity. In an iron foundry, which plays a pivotal roll in the iron and steel industry, after molten iron, which is pig iron in a molten state, is produced by using iron ore and coal as raw materials, steel is produced from the molten iron and then supplied to customers.

Currently, approximately 60% of the world's iron production is produced using a blast furnace method that has been in development since the 14th century. According to the blast furnace method, iron ore, which has gone through a sintering process, and coke, which is produced using bituminous coals as a raw material, are charged into a blast furnace together and oxygen is supplied thereto to reduce the iron ore to iron, thereby manufacturing molten iron.

The blast furnace method, which is the most popular in plants for manufacturing molten iron, requires that raw materials have strength of at least a predetermined level and have grain sizes that can ensure permeability in the furnace, taking into account reaction characteristics. For that reason, as described above, coke that is obtained by processing specific raw coals is used as a carbon source to be used as a fuel and as a reducing agent. Also, sintered ore that has gone through a successive agglomerating process is mainly used as an iron source.

Accordingly, the modern blast furnace method requires raw material preliminary processing equipment, such as coke manufacturing equipment and sintering equipment. That is, it is necessary to be equipped with subsidiary facilities in addition to the blast furnace, and to also have equipment for preventing and minimizing pollution generated from the subsidiary facilities. Therefore, there is a problem in that a heavy investment in the additional facilities and equipment leads to increased manufacturing costs. In order to solve these problems with the blast furnace method, significant effort has been made in iron works all over the world to develop a smelting reduction process that produces molten iron by directly using raw coals as a fuel and a reducing agent and by directly using fine ore, which account for more than 80% of the world's ore production. The apparatus for manufacturing molten iron according to a smelting reduction process includes a reduction reactor for reducing iron ore and a melter-gasifier in which a coal packed bed is formed. The melter-gasifier is connected to the reduction reactor. Fine ore and additives at room temperature are charged into the fluidized-bed reduction reactor to be pre- reduced.

Since hot reducing gas is supplied to the fluidized-bed reduction reactor from the melter-gasifier, temperatures of the fine ore and additives at room temperature are raised by contacting the hot reducing gas. The fine ore and additives at room temperature are reduced and plasticized in the fluidized-bed reduction reactor. The fine ore is charged into a fine iron storage bin to be stored and is then manufactured into briquettes by an apparatus for manufacturing briquettes, which are then charged into the melter-gasifier.

Meanwhile, when the fine ore is charged into the fine iron storage bin from the fluidized-bed reduction reactor, an offgas of the fluidized-bed reduction reactor is charged into the fine iron storage bin together with the offgas. After the offgas is transferred to an apparatus for processing an offgas through an offgas duct connected to the fine ore storage bin, dust contained in the offgas is removed and the offgas is cooled, and the offgas is then discharged. However, the offgas discharged from the fine ore storage bin contains a large amount of fine ore. This causes a dust collecting installation to be blocked and a generating amount of sludge to be increased, thereby raising the original production cost. In addition, dust scattered by a discharged gas pollutes the air.

DISCLOSURE Technical Problem An apparatus for restoring fine iron by collecting fine ore existing in an offgas discharged from a fine iron storage bin and recycling it is provided in order to reduce original production cost and air pollution. In addition, an apparatus for manufacturing molten iron including the apparatus for restoring fine iron is provided. Technical Solution

An apparatus for restoring fine iron according to an embodiment of the present invention includes a fine iron storage bin, and a cyclone that collects fine iron in an offgas that is supplied from the fine iron storage bin.

The apparatus for restoring fine iron may further include an offgas duct that is installed to be connected from an upper side of the fine iron storage bin to a side surface of the cyclone and that supplies the offgas of the fine iron storage bin to the cyclone. In addition, the apparatus for restoring fine iron may further include a slide gate that is installed below the cyclone and that charges the collected fine iron to the fine iron storage bin. The slide gate may include a first slide gate that is connected to a lower side of the cyclone, a second slide gate that is connected to an upper side of the fine iron storage bin, and a restoring hopper that is arranged between the first and second slide gates.

The apparatus for restoring fine iron may further include a gas supply device that is installed to be connected to the restoring hopper and form a positive pressure in the restoring hopper. The gas supply device may supply nitrogen gas to the restoring hopper. The apparatus for restoring fine iron may further include a bypass line that is connected to the off gas duct to discharge the off gas to a vent gas system without passing through the cyclone. The apparatus for restoring fine iron may further include a cyclone offgas duct that is installed on an upper side of the cyclone and that discharges an offgas of the cyclone that is separated from the fine iron to a vent gas system.

An apparatus for manufacturing molten iron according to an embodiment of the present invention includes at least one fluidized-bed reduction reactor that reduces and plasticizes fine iron; an apparatus for restoring fine iron into which the fine iron discharged from the fluidized-bed reduction reactor is charged; an apparatus for manufacturing compacted iron that molds the fine iron supplied from the apparatus for restoring fine iron and manufactures compacted iron; a melter-gasifier into which the compacted iron is charged and oxygen is injected, the melter-gasifier manufacturing molten iron; and a reducing gas supply line that supplies a reducing gas that is discharged from the melter-gasifier to the fluidized-bed reduction reactor. Advantageous Effects

An original production cost can be reduced by collecting fine iron discharged as sludge and recycling it In addition, an amount of the fine iron contained in the offgas is reduced to prevent pipes of a dust collecting installation from being blocked, and thereby installation operating efficiency can be raised and air pollution caused by the offgas can be reduced.

DESCRIPTION OF DRAWINGS FIG. 1 is a schematic view of an apparatus for manufacturing molten iron according to an embodiment of the present invention.

FIG. 2 is a schematic view of an apparatus for restoring fine iron according to an embodiment of the present invention.

FIGs. 3 and 4 are schematic views showing operating states of the apparatus for restoring fine iron, respectively.

BEST MODE Exemplary embodiments of the present invention will be explained in detail below with reference to the most preferable embodiment and attached drawings in order for those skilled in the art in a field of the present invention to easily perform the present invention. However, the embodiments are merely to illustrate the present invention and the present invention is not limited thereto.

FIG. 1 schematically shows an apparatus for manufacturing molten iron 100 according to an embodiment of the present invention. A structure of the apparatus for manufacturing molten iron 100 shown in FIG. 1 is merely to illustrate the present invention and the present invention is not limited thereto. Therefore, the apparatus for manufacturing molten iron 100 can be formed as other structures and further include other devices.

As shown in FIG. 1, the apparatus for manufacturing molten iron 100 includes a fluidized-bed reduction reactor 10 as a reduction reactor, an apparatus for restoring fine iron 20, an apparatus for manufacturing compacted iron 30, a melter-gasifier 40, and a reducing gas supply line 50. In addition, the apparatus for manufacturing molten iron 100 may further include a hot pressure equalizing device 60 connected between the apparatus for manufacturing compacted iron 30 and the melter-gasifier 40. Further, the apparatus for manufacturing molten iron 100 may include other devices necessary for manufacturing molten iron.

A fluidized bed is formed in fluidized-bed reduction reactors 10 that are connected to each other in order to reduced fine iron ore in the fluidized bed. A reducing gas that is discharged from the melter-gasifier 40 is supplied to each of the fluidized-bed reduction reactors 10 through the reducing gas supply line 50. The reducing gas flows in the fluidized-bed reduction reactors 10 and reduces the fine iron ore. In this case, additives can be used by mixing them with the fine iron ore.

Meanwhile, a plurality of fluidized-bed reduction reactors 10 can be provided. As shown in FIG. 1, for example, the fluidized-bed reduction reactors 10 include a preheating reduction reactor 10a, a first pre-reduction reactor 10b, a second pre-reduction reactor 10c, and a final reduction reactor 1Od. The apparatus for restoring fine iron 20 is connected to the final reduction reactor 1Od and restores reduced fine iron. The apparatus for restoring fine iron 20 supplies reduced fine iron as reduced materials to the apparatus for manufacturing compacted iron 30 installed therebelow. A detailed description of the apparatus for restoring fine iron 20 will be explained later.

The apparatus for manufacturing compacted iron 30 compacts the reduced materials in order to secure permeability of the melter-gasifier 40 and prevent scattering of dust. The apparatus for manufacturing compacted iron 30 includes a charging hopper 32, a pair of rolls 34, a crusher 36, and a compacted iron storage bin 38. In addition, the apparatus for manufacturing compacted iron 30 may further include other devices as necessary.

The charging hopper 32 restores reduced materials supplied from the apparatus for restoring fine iron 20, and the pair of rolls 34 compress the reduced materials to manufacture compacted reduced materials. The crusher 36 crushes the compacted reduced materials into a suitable size and the compacted iron storage bin 38 temporarily stores crushed reduced materials. The hot pressure equalizing device 60 is located between the apparatus for manufacturing compacted iron 30 and the melter-gasifier 40. The hot pressure equalizing device 60 is installed above the melter-gasifier 40 in order to control a pressure thereof. Since the pressure in the melter- gasifier 40 is high, the hot pressure equalizing device 60 uniformly controls the pressure, thereby easily charging the crushed compacted iron into the melter-gasifier 40.

Lumped coal or coal briquettes molded from pulverized coal is supplied to the melter-gasifier 40, thereby forming a coal packed bed therein. Lumped coal or coal briquettes charged into the melter-gasifier 40 are gasified by a pyrolytic reaction in an upper portion of the coal packed bed and a combustion reaction in a lower portion thereof caused by oxygen.

A hot reducing gas generated by a gasification reaction in the melter- gasifier 40 is subsequently supplied to the fluidized-bed reduction reactor 10 through a reducing gas supply line 50 connected to a rear end of the final reduction reactor 1Od₇ thereby being used as a reducing agent and a fluidizing gas. The apparatus for restoring fine iron 20 of FIG. 1 will be explained in more detail below.

FIG. 2 schematically shows the apparatus for restoring fine iron 20 of FIG. 1.

The apparatus for restoring fine iron 20 includes a fine iron storage bin 22, an offgas duct 24, a cyclone 26, a slide gate 28, and a bypass line 29. The fine iron storage bin 22 is connected to the above-described fluidized- bed reduction reactor 10 (shown in FIG. 1, the same hereinafter). The fine iron storage bin 22 stores the fine iron supplied from the fluidized-bed reduction reactor 10. The offgas duct 24 is arranged to connect an upper side of the fine iron storage bin 22 and a side surface of the cyclone 26. The offgas is transferred to the cyclone 26 through the offgas duct 24. The offgas contains a large amount of fine iron.

An offgas duct 26a is installed above the cyclone 26 and a slide gate 28 is installed therebelow. The slide gate 28 has a structure that is capable of opening and closing in order to charge fine iron collected in the cyclone 26 into the fine iron storage bin 22 again.

In addition, the slide gate 28 can include a first slide gate 28a connected to a lower side of the cyclone 26, a second slide gate 28b connected to an upper side of the fine iron storage bin 22, and a restoring hopper 28c arranged to be connected between the first and second slide gates 28a and 28b. In this case, the first and second slide gates 28a and 28b independently open and close. A bypass line 29 is connected to a vent gas system (not shown) from the offgas duct 24 without passing through the cyclone 26.

In the apparatus for restoring fine iron 20 having the above-described structure, fine iron contained in the offgas discharged from the fine iron storage bin 22 enters into the cyclone 26 after passing through the offgas duct 24. In this case, the fine iron sinks in the cyclone 26 to be separated by a specific gravity difference while the offgas from which the fine iron is separated is discharged from the cyclone offgas duct 26a to the vent gas system (not shown) and goes through a dust collecting process. In this case, the fine iron that sinks to a lower side of the cyclone 26 passes through the slide gate 28 and enters into the fine iron storage bin 22 again. Meanwhile, if the cyclone 26 is blocked or out of order, the offgas in the fine iron storage bin 22 does not pass through the cyclone 26 but passes through the offgas duct 24 and the bypass line 29, thereby being discharged into the vent gas system (not shown) and going through a dust collecting process.

FIGs. 3 and 4 are schematic views showing operating states of the slide gate 28, respectively.

As shown in FIG. 3, the first slide gate 28a is open to charge the fine iron collected in the cyclone 26 again in a state in which the second slide gate 28b is closed and a gas supply device 28d is connected to the slide gate 28. In this case, the first slide gate 28a is open for about 10 seconds. The fine iron having come down through the first slide gate 28a is restored in the restoring hopper 28c installed between the first and second slide gates 28a and 28b.

Next, as shown in FIG. 4, the second slide gate 28b is open as the first slide gate 28a is closed, hi this case, the gas supply device 28d supplies an inert gas such as nitrogen gas to the restoring hopper 28c at the same time as the second slide gate 28b is open. Therefore, pressure in the restoring hopper 28c becomes higher than that in the fine iron storage bin 22. As a result, the fine iron is prevented from being discharged outside of the fine iron storage bin 22 because of the pressure therein. As described above, the fine iron collected in the cyclone 26 is charged into the fine iron storage bin 22 again after passing through the slide gate 28. The fine iron is supplied to an apparatus for manufacturing compacted iron and reused.

Meanwhile, the offgas that is discharged from the cyclone offgas duct goes through a dust collecting process in the vent gas system for removing dust in the offgas. The vent gas system, which conducts a dust collecting process, may include a pre-scrubber, a vent gas bubbler, a vent gas scrubber, and a vent gas compressor. The offgas entering into the vent gas system goes through two steps of dust collecting processes in the pre-scrubber and the vent gas scrubber.

In this case, as described above, the fine iron is collected in the apparatus for restoring fine iron again and is charged into the fine iron storage bin, and thereby an amount of the fine iron in the offgas discharged from the offgas duct is relatively reduced. Therefore, a phenomenon in which pipes of the vent gas system are blocked due to the fine iron is largely reduced.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

WHAT IS CALIMED IS

1. An apparatus for restoring fine iron, the apparatus comprising: a fine iron storage bin; and a cyclone that collects fine iron in an offgas that is supplied from the fine iron storage bin.

2. The apparatus of Claim 1, further comprising an offgas duct that is installed to be connected from an upper side of the fine iron storage bin to a side surface of the cyclone and supplies the offgas of the fine iron storage bin to the cyclone.

3. The apparatus of Claim 2, further comprising a slide gate that is installed below the cyclone and charges the collected fine iron to the fine iron storage bin.

4. The apparatus of Claim 3, wherein the slide gate comprises: a first slide gate that is connected to a lower side of the cyclone; a second slide gate that is connected to an upper side of the fine iron storage bin; and a restoring hopper that is arranged between the first and second slide gates.

5. The apparatus of Claim 4, further comprising a gas supply device that is installed to be connected to the restoring hopper and form a positive pressure in the restoring hopper.

6. The apparatus of Claim 5, wherein the gas supply device supplies nitrogen gas to the restoring hopper.

7. The apparatus of Claim 2, further comprising a bypass line that is connected to the offgas duct to discharge the offgas to a vent gas system without passing through the cyclone.

8. The apparatus of Claim 1, further comprising a cyclone offgas duct that is installed on an upper side of the cyclone and discharges an offgas of the cyclone, which is separated from the fine iron, to a vent gas system.

9. An apparatus for manufacturing molten iron, the apparatus comprising: at least one fluidized-bed reduction reactor that reduces and plasticizes fine iron; an apparatus for restoring fine iron into which the fine iron discharged from the fluidized-bed reduction reactor is charged; an apparatus for manufacturing compacted iron that molds the fine iron supplied from the apparatus for restoring fine iron and manufactures compacted iron; a melter-gasifier into which the compacted iron is charged and oxygen is injected, the melter-gasifier manufacturing molten iron; and a reducing gas supply line that supplies a reducing gas discharged from the melter-gasifier to the fluidized-bed reduction reactor, wherein the apparatus for restoring fine iron comprises a fine iron storage bin, and a cyclone that collects fine iron in an offgas that is supplied from the fine iron storage bin.

10. The apparatus of Claim 9, further comprising an offgas duct that is installed to be connected from an upper side of the fine iron storage bin to a side surface of the cyclone and supplies the offgas of the fine iron storage bin to the cyclone.

11. The apparatus of Claim 10, further comprising a slide gate that is installed below the cyclone and charges the collected fine iron to the fine iron storage bin.

12. The apparatus of Claim 11, wherein the slide gate comprises: a first slide gate that is connected to a lower side of the cyclone; a second slide gate that is connected to an upper side of the fine iron storage bin; and a restoring hopper that is arranged between the first and second slide gates.

13. The apparatus of Claim 12, further comprising a gas supply device that is installed to be connected to the restoring hopper and form a positive pressure in the restoring hopper.

14. The apparatus of Claim 13, wherein the gas supply device supplies nitrogen gas to the restoring hopper.

15. The apparatus of Claim 10 further comprising a bypass line that is connected to the offgas duct to discharge the offgas to a vent gas system without passing through the cyclone.

16. The apparatus of Claim 9 further comprising a cyclone offgas duct that is installed on an upper side of the cyclone and discharges an offgas of the cyclone, which is separated from the fine iron, to a vent gas system.